On-press development type planographic printing plate original plate, method for producing planographic printing plate, planographic printing method, and compound

Abstract

This on-press development type planographic printing plate original plate includes a support body and an image recording layer on the support body, wherein the image recording layer includes (1) or (2).　(1) A borate compound represented by formula (1), and an electron-accepting polymerization initiator.　(2) A borate compound represented by formula (1a).　In formula (1) and formula (1a), R1, R2, R3, and R4 each independently represent a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted alkenyl group, or a substituted or unsubstituted alkynyl group, and R1, R2, R3, and R4 each independently may have a ring structure. However, at least one of R1, R2, R3, and R4 differs from the others. M+ represents a cation. Ma+ represents an iodonium cation.

Description

On-press development type lithographic printing plate precursor, method for producing lithographic printing plate, lithographic printing method, and compound

[0001] The present disclosure relates to an on-press development type lithographic printing plate precursor, a method for preparing a lithographic printing plate, a lithographic printing method, and a compound.

[0002] Generally, a lithographic printing plate comprises an oleophilic image area that accepts ink during the printing process and a hydrophilic non-image area that accepts fountain solution. Lithographic printing utilizes the mutual repulsion of water and oil-based ink, with the oleophilic image area of ​​the lithographic printing plate serving as the ink-receptive area and the hydrophilic non-image area serving as the fountain solution-receptive area (ink-non-receptive area), creating a difference in ink adhesion on the surface of the lithographic printing plate. After ink is applied only to the image area, the ink is transferred to a substrate such as paper for printing. To prepare such lithographic printing plates, a lithographic printing plate precursor (PS plate) comprising an oleophilic photosensitive resin layer (image-recording layer) provided on a hydrophilic support has been widely used. Typically, a lithographic printing plate precursor is exposed to light through an original image such as a lithographic film, and then the image areas of the image recording layer are left, while the other unnecessary image recording layer is dissolved and removed with an alkaline developer or an organic solvent, exposing the hydrophilic support surface and forming non-image areas, thereby producing a lithographic printing plate.

[0003] Furthermore, growing concern about the global environment has focused attention on environmental issues related to wastewater from wet processes such as development. To address these environmental issues, efforts are being made to simplify development or platemaking, or to eliminate such processes. One simple production method is known as "on-press development." This method involves exposing a lithographic printing plate precursor to light, without the conventional development process, and directly mounting the plate on a printing press, and removing unnecessary portions of the image-recording layer at an early stage of the normal printing process. In the present disclosure, a lithographic printing plate precursor that can be used for such on-press development is referred to as an "on-press development type lithographic printing plate precursor."

[0004] Examples of conventional lithographic printing plate precursors include those described in JP-A-2020-069789 and JP-A-2011-186367. JP-A-2020-069789 discloses a lithographic printing plate precursor having an image recording layer on a support, the image recording layer including an infrared absorber that decomposes upon exposure to infrared light, a binder polymer having structural units formed from an aromatic vinyl compound, a polymerization initiator, and a polymerizable compound.

[0005] JP 2011-186367 A describes a lithographic printing plate precursor comprising a photosensitive composition comprising (A) an organic boron salt represented by the following general formula I, (B) a trihaloalkyl-substituted compound, (C) a cyanine dye having absorption in the wavelength range of 400 nm to 900 nm, and (D) a compound having a polymerizable double bond group:

[0006]

[0007] In general formula I, R １ , R ２ , R ３ , R ４ represents an aryl group represented by the following general formula II, A ＋ represents a group capable of forming a cation. ５ , R ６ , R ７ , R ８ , R ９ each independently represents a hydrogen atom or a group selected from an alkyl group, alkylene group, alkoxy group, or aryl group having 1 to 10 carbon atoms, and some of these may be bonded to form a ring.

[0008]

[0010] An object of one embodiment of the present disclosure is to provide an on-press development type lithographic printing plate precursor that is excellent in printing durability and suppression of development defects over time. An object of another embodiment of the present disclosure is to provide a method for producing a lithographic printing plate using the on-press development type lithographic printing plate precursor, or a lithographic printing method. An object of yet another embodiment of the present disclosure is to provide a novel borate compound.

[0009] The means for solving the above problems include the following aspects.

[0010] <1> An on-press development type lithographic printing plate precursor having a support and an image recording layer on the support, wherein the image recording layer contains the following (1) or (2): (1) a borate compound represented by the following formula (1), and an electron-accepting polymerization initiator:

[0011]

[0012] In formula (1), R １ , R ２ , R ３ , and R ４ each independently represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted alkenyl group, or a substituted or unsubstituted alkynyl group; R １ , R ２ , R ３ , and R ４ may each independently have a ring structure. １ , R ２ , R ３ , and R ４ At least one of the M is different from the others. ＋ represents a cation.

[0013] (2) A borate compound represented by the following formula (1a):

[0014]

[0015] In formula (1a), R １ , R ２ , R ３ , and R ４ each independently represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted alkenyl group, or a substituted or unsubstituted alkynyl group; R １ , R ２ , R ３ , and R ４ may each independently have a ring structure. １ , R ２ , R ３ , and R ４ At least one of them is different from the others.＋ represents an iodonium cation.

[0016] <2> R in formula (1) or formula (1a) １ , R ２ , and R ３ is a phenyl group, and R ４ but, １ , R ２ , and R ３ <3> The on-press development type lithographic printing plate precursor according to <1>, wherein R in formula (1) or formula (1a) is different from １ , R ２ , and R ３ is a phenyl group, and R ４ <4> The on-press development type lithographic printing plate precursor according to <1> or <2>, wherein M in formula (1) is an aryl group having a substituent. ＋ <5> The on-press development type lithographic printing plate precursor according to any one of <1> to <3>, wherein M in formula (1) is an inorganic cation. ＋ <6> The on-press development type lithographic printing plate precursor according to any one of <1> to <3>, wherein R in Formula (1) or Formula (1a) is at least one cation selected from the group consisting of iodonium cations and infrared absorbing dye cations. １ , R ２ , and R ３ is a phenyl group, and R ４ <7> The on-press developable lithographic printing plate precursor according to any one of <1> to <5>, wherein R is a substituted aryl group, and the total number of carbon atoms and oxygen atoms in the substituent is 2 or more. <8> The on-press developable lithographic printing plate precursor according to <6>, wherein the total number of carbon atoms and oxygen atoms in the substituent is 3 or more. <9> The on-press developable lithographic printing plate precursor according to <7>, wherein R in formula (1a) or (1b) is a substituted aryl group, and the total number of carbon atoms and oxygen atoms in the substituent is 3 or more. １ , R ２ , and R ３ is a phenyl group substituted with an electron-withdrawing group, and R ４ But, R １ , R ２ , and R ３ <9> The on-press development type lithographic printing plate precursor according to any one of <1> to <7>, wherein R in formula (1) or (1a) is a group different from ４is at least one group selected from the group consisting of an alkyl group, an aryl group, an alkenyl group, an alkoxy group, an ester group, a carbonyl group, and an amide group. <10> The on-press developable lithographic printing plate precursor according to any one of <1> to <9>, wherein the image recording layer contains a color former. <11> The on-press developable lithographic printing plate precursor according to any one of <1> to <10>, wherein the image recording layer contains an infrared absorber. <12> The on-press developable lithographic printing plate precursor according to any one of <1> to <11>, wherein the electron-accepting polymerization initiator contains a compound represented by the following formula (Ia) and at least one compound B selected from the group consisting of compounds represented by the following formula (Ib) or (Ic):

[0017]

[0018] In formulas (Ia) to (Ic), R １ , R ２ , R ３ , R ４ , R ５ and R ６ are each independently a substituted or unsubstituted alkyl group or a substituted or unsubstituted alkoxy group having 2 to 9 carbon atoms, and R ３ and R ４ At least one of １ or R ２ Unlike R １ and R ２ The total number of carbon atoms in ３ and R ４ The difference between the total number of carbon atoms in R １ and R ２ The total number of carbon atoms in ５ and R ６ The difference between the total number of carbon atoms in X is 0 to 4. １ , X ２ and X ３ are each independently a counter anion.

[0019] <13> The on-press development type lithographic printing plate precursor according to <11>, wherein the infrared absorber contains a compound represented by the following formula (X):

[0020]

[0021] In formula (X), Ar １１ and Ar １２ each independently represents an atomic group necessary to form a substituted or unsubstituted aromatic ring or a substituted or unsubstituted heteroaromatic ring; R １１ and R １２ are each independently a substituted or unsubstituted alkyl group, R １３ represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group; R １４ represents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group; Y each independently represents an oxygen atom, a sulfur atom, or >C(R １５ R １６ ) represents a dialkylmethylene group represented by R １５ and R １６ each independently represents a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms; A １ and A ２ each independently represent a substituted or unsubstituted alkyl group or a group of atoms containing 2 or 3 carbon atoms necessary to form a substituted or unsubstituted 5- or 6-membered non-aromatic carbocyclic ring by linking together, and Za represents a counter ion that neutralizes charge. <14> The on-press developable lithographic printing plate precursor according to <11>, wherein the infrared absorber contains a compound represented by the following formula 1:

[0022]

[0023] In formula 1, R １ and R ２ each independently represents a hydrogen atom or an alkyl group; R １ and R ２ may be linked to each other to form a ring, R ３ ~R ６ each independently represents a hydrogen atom or an alkyl group; R ７ and R ８ each independently represents an alkyl group or an aryl group; Y １ and Y ２are each independently an oxygen atom, a sulfur atom, or —NR ０ - or a dialkylmethylene group, R ０ represents a hydrogen atom, an alkyl group, or an aryl group; Ar １ and Ar ２ each independently represents a group forming a benzene ring or a naphthalene ring which may have a group represented by the formula 2 described below; A １ is -NR ９ R １０ , -X １ -L １ or a group represented by formula 2 described below, R ９ and R １０ each independently represents an alkyl group, an aryl group, an alkoxycarbonyl group, or an arylsulfonyl group; X １ represents an oxygen atom or a sulfur atom, L １ is a hydrocarbon group, a heteroaryl group, or a group that is converted by heat or infrared exposure to X １ represents a group that cleaves the bond with Ar; Za represents a counter ion that neutralizes the charge; １ and Ar ２ At least one of the above has a group represented by the following formula 2: -X Formula 2 In formula 2, X is a halogen atom, -C(=O)-X ２ -R １１ , -C(=O)-NR １２ R １３ , -OC(=O)-R １４ , -CN, -SO ２ NR １５ R １６ or a perfluoroalkyl group, X ２ represents a single bond or an oxygen atom, R １１ and R １４ each independently represents an alkyl group or an aryl group; R １２ , R １３ , R １５ and R １６ each independently represents a hydrogen atom, an alkyl group, or an aryl group.

[0024] <15> The on-press development type lithographic printing plate precursor according to <11>, wherein the infrared absorber contains a compound represented by the following formula (P1):

[0025]

[0026] In formula (P1), R Ｐ１ represents a group represented by the following formula (P2) or formula (P3), and R Ｐ２ and R Ｐ３ each independently represents a hydrogen atom or an alkyl group; R Ｐ２ and R Ｐ３ may be linked to each other to form a ring, and Ar Ｐ１ and Ar Ｐ２ each independently represents a benzene ring or a naphthalene ring; Y Ｐ１ and Y Ｐ２ are each independently an oxygen atom, a sulfur atom, or —NR Ｐ０ - or a dialkylmethylene group, R Ｐ４ and R Ｐ５ each independently represents an alkyl group; R Ｐ６ ~R Ｐ９ each independently represents a hydrogen atom or an alkyl group; R Ｐ０ represents a hydrogen atom, an alkyl group, or an aryl group, and Za represents a counter ion that neutralizes the charge.

[0027]

[0028] In formula (P2) and formula (P3), R Ｐ１０ represents a monovalent organic group having an aryl group, and R Ｐ１１ ~R Ｐ１４ and R Ｐ１７ ~R Ｐ２０ each independently represents a hydrogen atom, an alkyl group, an aryl group, a hydroxy group, an alkoxy group, or a halogen atom; R Ｐ１５ and R Ｐ１６ each independently represents a hydrogen atom, an alkyl group, or an aryl group; R Ｐ１１ ~R Ｐ２０ At least two of these may be bonded to form a ring structure, and * represents a single bond bonding to the oxygen atom in formula (P1).

[0029] <16> The on-press development type lithographic printing plate precursor according to any one of <1> to <15>, in which the image recording layer contains a polymer BB having a structural unit represented by the following formula (BI):

[0030]

[0031] In formula (BI), R Ｂ１１ and R Ｂ１２ each independently represents a hydrogen atom or an alkyl group, R Ｂ１３ represents a hydrogen atom or a monovalent substituent, L Ｂ１１ and L Ｂ１２ each independently represents a single bond or a divalent linking group, and Rh represents a substituent containing two or more silicon atoms.

[0032] <17> A method for preparing a lithographic printing plate, comprising: a step of imagewise exposing the on-press developable lithographic printing plate precursor according to any one of <1> to <16>, and a step of supplying at least one selected from the group consisting of printing ink and fountain solution on a printing press to remove the image recording layer in non-image areas. <18> A lithographic printing method, comprising: a step of imagewise exposing the on-press developable lithographic printing plate precursor according to any one of <1> to <16>, and a step of supplying at least one selected from the group consisting of printing ink and fountain solution on a printing press to remove the image recording layer in non-image areas to prepare a lithographic printing plate, and a step of printing with the obtained lithographic printing plate. <19> A compound represented by the following formula (I):

[0033]

[0034] In formula (I), R represents a group having a total number of carbon atoms and oxygen atoms of 2 or more, X represents a halogen atom, an alkyl group, or an alkoxy group, and the sum of the Hammett values ​​of R and X is −0.09 to 0.09. ＋ Li ＋ , Na ＋ , K. ＋ , iodonium cation, or infrared absorbing dye cation.

[0035] <20> The compound according to <19>, wherein R in formula (I) represents an alkyl group having 2 to 4 carbon atoms, and X is a halogen atom.

[0036] <21> A compound represented by the following formula (II):

[0037]

[0038] In formula (II), R represents an alkyl group having two or more carbon atoms, or an alkoxy group having two or more carbon atoms and oxygen atoms in total. ＋ represents an iodonium cation or an infrared absorbing dye cation.

[0039] <22> The compound according to <21>, wherein R in formula (II) is an alkyl group having from 2 to 4 carbon atoms in total, or an alkoxy group having from 2 to 4 carbon atoms in total. <23> The compound represented by B-7, B-25, B-26, B-29, or B-30.

[0040]

[0041] According to one embodiment of the present disclosure, it is possible to provide an on-press development type lithographic printing plate precursor that is excellent in printing durability and suppression of development defects over time. Furthermore, according to another embodiment of the present disclosure, it is possible to provide a method for producing a lithographic printing plate using the on-press development type lithographic printing plate precursor, or a lithographic printing method. Furthermore, according to another embodiment of the present disclosure, it is possible to provide a novel borate compound.

[0042] 1 is a schematic cross-sectional view of one embodiment of a support; FIG. 2 is a schematic cross-sectional view of another embodiment of a support; FIG. 3 is a schematic view of an anodizing treatment device used in an anodizing treatment in a method for producing a support having an anodized film; １ 1H-NMR chart of Compound B-7. １ 1H-NMR chart of Compound B-8. １ 1H-NMR chart of compound B-25. １ 1H-NMR chart of compound B-26. １ 1H-NMR chart of compound B-29. １ 1H-NMR chart of compound B-30. １ 1H-NMR chart of compound B-34. １ 1H-NMR chart of compound B-35. １ 1H-NMR chart of compound B-36. １ 1H-NMR chart of compound B-37. １ 1H-NMR chart of compound B-38.１ 1H-NMR chart of compound B-39. １ 1H-NMR chart of compound B-40. １ 1H-NMR chart of compound B-41. １ 1H-NMR chart of compound B-42. １ 1H-NMR chart of compound B-45. １ 1H-NMR chart of compound B-46. １ 1H-NMR chart.

[0043] The contents of the present disclosure will be described in detail below. The following description of the constituent elements may be based on a representative embodiment of the present disclosure, but the present disclosure is not limited to such an embodiment. In the present disclosure, the term "to" indicating a numerical range is used to mean that the numerical values ​​before and after the term are included as the lower and upper limits. Furthermore, in the notation of groups (atomic groups) in the present disclosure, notations that do not indicate substituted or unsubstituted encompass both unsubstituted and substituted groups. For example, the term "alkyl group" encompasses not only unsubstituted alkyl groups (unsubstituted alkyl groups) but also substituted alkyl groups (substituted alkyl groups). In the present disclosure, "(meth)acrylic" is a term used to encompass both acrylic and methacrylic groups, and "(meth)acryloyl" is a term used to encompass both acryloyl and methacryloyl groups. The term "process" in the present disclosure includes not only independent processes, but also processes that cannot be clearly distinguished from other processes, as long as the intended purpose of the process is achieved. In the present disclosure, "mass %" and "wt %" are synonymous, and "parts by mass" and "parts by weight" are synonymous. Unless otherwise specified, in the present disclosure, each component in the composition or each structural unit in the polymer may be contained alone or in combination of two or more types. In the present disclosure, when a plurality of substances or structural units corresponding to each component or each structural unit in the polymer is present in the composition, the amount of each component in the composition or each structural unit in the polymer means the total amount of the corresponding plurality of substances present in the composition or the corresponding plurality of structural units present in the polymer, unless otherwise specified. In the present disclosure, a combination of two or more preferred embodiments is a more preferred embodiment.Unless otherwise specified, the weight-average molecular weight (Mw) and number-average molecular weight (Mn) in this disclosure are molecular weights measured by a gel permeation chromatography (GPC) analyzer using columns of TSKgel GMHxL, TSKgel G4000HxL, or TSKgel G2000HxL (all trade names manufactured by Tosoh Corporation) in THF (tetrahydrofuran) as a solvent, detected by a differential refractometer, and converted using polystyrene as a standard. In this disclosure, the term "lithographic printing plate precursor" encompasses not only lithographic printing plate precursors but also disposable plate precursors. The term "lithographic printing plate" encompasses not only lithographic printing plates prepared from lithographic printing plate precursors, if necessary, through procedures such as exposure and development, but also disposable plates. In the case of disposable plate precursors, exposure and development procedures are not necessarily required. It should be noted that a throwaway plate is a lithographic printing plate precursor that is attached to an unused plate cylinder when, for example, a portion of a page is printed in one color or two colors in color newspaper printing. In the present disclosure, "*" in a chemical structural formula indicates a bonding position with other structures.

[0044] <On-press development type lithographic printing plate precursor> The on-press development type lithographic printing plate precursor (also simply referred to as "lithographic printing plate precursor") according to the present disclosure has a support and an image recording layer on the support, and the image recording layer contains the following (1) or the following (2): (1) a borate compound represented by formula (1) and an electron-accepting polymerization initiator (2) a borate compound represented by formula (1a) The lithographic printing plate precursor according to the present disclosure is preferably a negative-working lithographic printing plate precursor in which exposed areas are polymerized by infrared exposure.

[0045] The present inventors have discovered that it is difficult to obtain a lithographic printing plate precursor having excellent printing durability and suppression of development defects over time using conventional lithographic printing plate precursors such as those described in JP 2020-069789 A or JP 2011-186367 A. Therefore, as a result of extensive research, the present inventors have discovered that by including an image recording layer having the above-described composition, a lithographic printing plate precursor having excellent printing durability and suppression of development defects over time can be obtained. The detailed mechanism by which the above effect is achieved is unknown, but is speculated as follows. The degree of hardening of the exposed area (image area) is thought to be one of the factors that causes a decrease in printing durability. The degree of hardening of the exposed area is affected by the amount of radicals generated by the reaction of a polymerization initiator, such as a borate compound, contained in the image recording layer. Because the reaction of the polymerization initiator depends on the potential of the polymerization initiator, the amount of radicals generated can be adjusted by controlling the potential. Compared with borate compounds having a symmetric structure, borate compounds having an asymmetric structure represented by formula (1) or formula (1a) allow for precise potential control and the amount of radicals generated can be adjusted. It is believed that this results in improved printing durability. One of the factors behind the decrease in the ability to suppress development defects over time is thought to be the adhesion of products resulting from the reaction between the borate compound contained in the image recording layer and other compounds to non-image areas. Therefore, it is believed that the use of a borate compound having an asymmetric structure represented by formula (1) or formula (1a) can inhibit reactions with other compounds through steric hindrance. As a result, the generation of products that cause ink adhesion to non-image areas is suppressed, improving the ability to suppress development defects over time. For these reasons, the lithographic printing plate precursor according to the present disclosure is excellent in printing durability and suppression of development defects over time.

[0046] Hereinafter, each constituent element of the lithographic printing plate precursor according to the present disclosure will be described in detail. In this disclosure, unless otherwise specified, the image recording layer includes the above-mentioned aspects (1) and (2). Hereinafter, the above-mentioned aspect (1) of the image recording layer will also be referred to as "aspect A." The above-mentioned aspect (2) of the image recording layer will also be referred to as "aspect B." Furthermore, hereinafter, unless otherwise specified, the borate compound represented by formula (1) and the borate compound represented by formula (1a) will also be collectively referred to as "specific borate compounds."

[0047] (Image Recording Layer) The image recording layer in the lithographic printing plate precursor according to the present disclosure is preferably a water-soluble or water-dispersible negative image recording layer. From the viewpoint of on-press developability, it is also preferable that the unexposed portion of the image recording layer in the lithographic printing plate precursor according to the present disclosure is removable with at least one of fountain solution and printing ink.

[0048] Each component contained in the image recording layer will be described in detail below.

[0049] [Aspect A] <Borate Compound Represented by Formula (1) (Specific Borate Compound)> The image recording layer in Aspect A contains a borate compound represented by the following formula (1). The borate compound represented by formula (1) is used as an electron-donating polymerization initiator in the image recording layer. The specific borate compound is a compound that generates polymerization initiating species such as radicals or cations by the energy of light, heat, or both.

[0050]

[0051] In formula (1), R １ , R ２ , R ３ , and R ４ each independently represents an unsubstituted or substituted alkyl group, an unsubstituted or substituted aryl group, an unsubstituted or substituted alkenyl group, or an unsubstituted or substituted alkynyl group; R １ , R ２ , R ３ , and R ４ teeth 、 Each of them may independently have a ring structure. １ , R ２, R ３ , and R ４ At least one of them is different from the others. ＋ represents a cation.

[0052] R １ , R ２ , R ３ , or R ４ Examples of the alkyl group represented by the formula (I) include alkyl groups having 1 to 20 carbon atoms, such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, a hexadecyl group, an octadecyl group, an eicosyl group, an isopropyl group, an isobutyl group, a s-butyl group, a t-butyl group, an isopentyl group, a neopentyl group, a 1-methylbutyl group, an isohexyl group, a 2-ethylhexyl group, a 2-methylhexyl group, a cyclohexyl group, a cyclopentyl group, and a 2-norbornyl group. The alkyl group may be linear, branched, or have a ring structure.

[0053] Also, R １ , R ２ , R ３ , or R ４ The alkyl group represented by R may have a substituent. Examples of the substituent of the alkyl group include a halogen atom, an alkyl group, an aryl group, an alkenyl group, an alkoxy group, an ester group, a carbonyl group, a sulfonyl group, an amino group, an amide group, and a combination thereof. １ , R ２ , R ３ , or R ４ The alkyl groups represented by the formula (I) are each independently preferably an unsubstituted, linear or branched alkyl group having 1 to 12 carbon atoms, more preferably an unsubstituted, linear or branched alkyl group having 1 to 10 carbon atoms, and even more preferably an unsubstituted, linear or branched alkyl group having 1 to 6 carbon atoms. Of these, from the viewpoint of suppressing development defects over time, a branched, unsubstituted alkyl group is particularly preferred.

[0054] R １ , R ２ , R ３ , or R ４Examples of the aryl group represented by the formula (I) include aryl groups having 6 to 20 carbon atoms, such as phenyl, naphthyl, anthryl, phenanthryl, indenyl, acenabutenyl, and fluorenyl. Examples of the substituent on the aryl group include the above-mentioned alkyl group substituents. １ , R ２ , R ３ , or R ４ The aryl groups represented by the following formula (I) are each independently preferably an unsubstituted or substituted phenyl group.

[0055] R １ , R ２ , R ３ , or R ４ Examples of the alkenyl group represented by R include alkenyl groups having 2 to 20 carbon atoms, such as vinyl, 1-propenyl, 1-butenyl, cinnamyl, and 2-chloro-1-ethenyl. １ , R ２ , R ３ , or R ４ The alkenyl group represented by the formula (I) may be linear, branched, or have a ring structure. Examples of the substituent of the alkenyl group include the above-mentioned substituents of the alkyl group. １ , R ２ , R ３ , or R ４ The alkenyl groups represented by the following formula (I) are each independently preferably an unsubstituted alkenyl group having 2 to 20 carbon atoms.

[0056] R １ , R ２ , R ３ , or R ４ Examples of the alkynyl group represented by the formula (I) include alkynyl groups having 2 to 20 carbon atoms, such as an ethynyl group, a 1-propynyl group, a 1-butynyl group, a trimethylsilylethynyl group, a phenylethynyl group, etc. The alkynyl group may be linear or branched.

[0057] Among the above functional groups, R １ , R ２ , R ３ , and R４ are preferably each independently a substituted or unsubstituted aryl group. １ , R ２ , R ３ , and R ４ are each independently a substituted or unsubstituted aryl group, the HOMO potential of the borate compound is lowered, improving the film stability of the image recording layer, thereby extending the life of the lithographic printing plate.

[0058] In this disclosure, R １ , R ２ , R ３ , and R ４ At least one of them is different from the others. １ , R ２ , R ３ , and R ４ Among them, R １ , R ２ , and R ３ are identical, and R ４ But, R １ , R ２ , and R ３ This allows a high purity borate compound to be obtained. In addition, the generation of radicals can be suppressed, making it difficult for side reactions to occur. In the above case, R １ , R ２ , and R ３ However, it is more preferably a phenyl group.

[0059] Also, R １ , R ２ , R ３ , and R ４ It is also preferred that at least two of R are phenyl groups and at least one is a substituted aryl group. １ , R ２ , and R ３ is a phenyl group, and R ４ is more preferably an aryl group having a substituent (i.e., a substituted aryl group).

[0060] R １ , R ２ , and R ３ is a phenyl group, and R４ When the aryl group has a substituent, the total number of carbon atoms and oxygen atoms in the substituent of the aryl group is preferably 2 or more, and more preferably 3 or more. The upper limit is, for example, 8 or less.

[0061] The compound represented by formula (1) is preferably a compound represented by the following formula (II):

[0062]

[0063] In formula (II), R represents an alkyl group having two or more carbon atoms, or an alkoxy group having two or more carbon atoms and oxygen atoms in total. ＋ represents an iodonium cation or an infrared absorbing dye cation.

[0064] In formula (II), the alkyl group represented by R preferably has 2 to 8 carbon atoms, more preferably 2 to 6 carbon atoms, and even more preferably 2 to 4 carbon atoms. Examples of the alkyl group include an ethyl group, a propyl group, an n-butyl group, a tert-butyl group, an isobutyl group, a sec-butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a neopentyl group, and an isopropyl group. The alkyl group may be linear, branched, or have a ring structure.

[0065] In formula (II), the alkoxy group represented by R preferably has a total of 2 to 4 carbon atoms and oxygen atoms. Examples of the alkoxy group include a methoxy group, an n-propoxy group, an isopropoxy group, and an n-butoxy group. The alkoxy group may be linear or branched.

[0066] In addition, in formula (1), R １ , R ２ , or R ３ The phenyl group represented by the formula (I) is preferably a phenyl group substituted with an electron-withdrawing group. Examples of the electron-withdrawing group include a halogen atom and a fluoroalkyl group. Among these, a fluorine atom, a chlorine atom, and a fluoroalkyl group having 1 to 3 carbon atoms are preferred.

[0067] In formula (1), R ４ The substituent that the aryl group represented by the formula (I) has is preferably an alkyl group, an aryl group, an alkenyl group, an alkoxy group, an ester group, a carbonyl group, or an amide group, more preferably an alkyl group, an alkenyl group, or an alkoxy group, and still more preferably an alkyl group or an alkoxy group.

[0068] In the present disclosure, the compound represented by the above formula (1) may be a compound represented by the following formula (I):

[0069]

[0070] In formula (I), R represents a group having a total number of carbon atoms and oxygen atoms of 2 or more, X represents a halogen atom, an alkyl group, or an alkoxy group, and the sum of the Hammett values ​​of R and X is −0.09 to 0.09. ＋ Li ＋ , Na ＋ , K. ＋ , iodonium cation, or infrared absorbing dye cation.

[0071] Examples of R in formula (I) include an alkyl group, an aryl group, an alkenyl group, an alkoxy group, an ester group, a carbonyl group, a sulfonyl group, an amide group, and combinations thereof.

[0072] In formula (I), examples of the halogen atom represented by X include a fluorine atom, a chlorine atom, and a bromine atom. The alkyl group and alkoxy group represented by X in formula (I) are the same as the alkyl group and alkoxy group in formula (II), and preferred embodiments are also the same.

[0073] In particular, R in formula (I) is preferably an alkyl group having 2 to 4 carbon atoms or an alkoxy group having 2 to 4 carbon atoms in total, and more preferably an alkyl group having 2 to 4 carbon atoms. In the above case, X is preferably a halogen atom. Here, the halogen atoms may each independently be different halogen atoms, but it is more preferable that all of them are the same halogen atom.

[0074] In formula (I), the sum of the Hammett σ values ​​of the substituents (R and X) introduced into the aryl skeleton is preferably within the range of -0.2 to 0.2, and more preferably within the range of -0.09 to 0.09. By being within this range, the HOMO potential can be adjusted to a desired range, and an excellent balance between the film stability and printing durability of the image recording layer is achieved. In the present disclosure, the sum of the Hammett σ values ​​of the substituents introduced into the aryl skeleton was calculated using the values ​​described in the reference "Chemical Seminar 10: Hammett Side - Structure and Reactivity -" (by Naoki Inamoto, Maruzen Co., Ltd., published in June 1983).

[0075] M in formula (1) ＋ represents a cation. ＋ is a counter cation of the boron anion. ＋ is not particularly limited as long as it is a cation that can neutralize the boron anion, but from the viewpoint of suppressing staining during development, it is preferably at least one selected from the group consisting of inorganic cations, iodonium cations, and infrared absorbing dye cations. One counter cation may be used alone, or two or more counter cations may be used in combination. In formula (I), M ＋ Li ＋ , Na ＋ , K. ＋ , an iodonium cation, or an infrared absorbing dye cation. ＋ represents an iodonium cation or an infrared absorbing dye cation.

[0076] When two or more counter cations are used, the combination is not particularly limited, but is preferably a combination of inorganic cations, a combination of iodonium cations, or a combination of infrared absorbing dye cations, and more preferably a combination of iodonium cations or a combination of infrared absorbing dye cations, which further improves the ability to suppress development defects over time and printing durability.

[0077] The iodonium cation may be the cation moiety of an electron-accepting polymerization initiator described later, and the infrared absorbing dye cation may be the cation moiety of an infrared absorber described later. In the image recording layer, the cation moiety of the electron-donating polymerization initiator and the cation moiety of the infrared absorber can bond with the anion moiety of the borate compound represented by formula (1) to form a salt.

[0078] Examples of inorganic cations include lithium cations, sodium cations, potassium cations, calcium cations, and magnesium cations. Among these, sodium cations, lithium cations, and potassium cations are preferred, and sodium cations are more preferred.

[0079] As the iodonium cation, the cation moiety of the electron-accepting polymerization initiator described below can be used. Specific examples are shown in the following structural formulas: In the following structural formulas, Me represents a methyl group. Note that the iodonium cation is not limited to the following specific examples.

[0080]

[0081] The infrared absorbing dye cation can be the cation moiety of the infrared absorber described below. Specific examples are shown in the following structural formulas: In the following structural formulas, Me represents a methyl group, and Bu represents a butyl group. Note that the infrared absorbing dye cation is not limited to the following specific examples.

[0082]

[0083]

[0084] From the viewpoint of chemical resistance and printing durability, the highest occupied molecular orbital (HOMO) of the specific borate compound is preferably −6.0 eV or more, more preferably −5.95 eV or more, and even more preferably −5.93 eV or more. The upper limit is preferably −5.00 eV or less, more preferably −5.40 eV or less, and particularly preferably −5.93 eV to −5.70 eV.

[0085] In the present disclosure, calculations of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) are performed using the following method. First, the counter anion in the compound to be calculated is ignored. Quantum chemistry calculation software Gaussian09 is used, and structural optimization is performed using DFT (B3LYP / 6-31G(d)). MO (molecular orbital) energy calculations are performed using DFT (B3LYP / 6-31+G(d,p) / CPCM (solvent=methanol)) with the structure obtained by the structural optimization. The MO energy Ebare (unit: hearttree) obtained in the above MO energy calculation is converted to Escaled (unit: eV), which is used as the HOMO and LUMO values ​​in the present disclosure, using the following formula: Escaled = 0.823168 x 27.2114 x Ebare - 1.07634 Note that 27.2114 is simply a coefficient for converting heartle to eV, and 0.823168 and -1.07634 are adjustment coefficients that are determined so that the HOMO and LUMO of the compound to be calculated match the measured values.

[0086] Preferred specific examples of the borate compound represented by formula (1) (hereinafter also referred to as specific borate compound) are shown below, but are not limited to these: In the following structural formula, Me represents a methyl group.

[0087]

[0088]

[0089]

[0090]

[0091]

[0092]

[0093] [Aspect B] <Borate Compound Represented by Formula (1a)> The image recording layer in aspect B contains a borate compound represented by the following formula (1a): The borate compound represented by formula (1a) is one aspect of the borate compound represented by formula (1), and is used as an electron-donating polymerization initiator in the image recording layer.

[0094]

[0095] In formula (1a), R １ , R ２ , R ３ , and R ４ each independently represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted alkenyl group, or a substituted or unsubstituted alkynyl group; R １ , R ２ , R ３ , and R ４ may each independently have a ring structure. １ , R ２ , R ３ , and R ４ At least one of them is different from the others. ＋ represents an iodonium cation.

[0096] In formula (1a), R １ , R ２ , R ３ , and R ４ is R in the above formula (1). １ , R ２ , R ３ , and R ４ The same applies to the preferred embodiments.

[0097] In formula (1a), Ma ＋ represents an iodonium cation. That is, the iodonium cation is a counter cation of the boron anion. In the present disclosure, the iodonium cation is not particularly limited as long as it is a cation that can neutralize the boron anion. Only one type of iodonium cation may be contained, or two or more types may be contained.

[0098] Examples of iodonium cations include those represented by the structural formulas explained in the section on embodiment A above.

[0099] The highest occupied molecular orbital (HOMO) of the borate compound represented by formula (1a) is similar to the preferred embodiment of the borate compound represented by formula (1). The calculation of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) is also similar to the above method.

[0100] Preferred specific examples of the borate compound represented by formula (1a) include, but are not limited to, the above-mentioned B-18, B-19, B-31 to B-33, B-45, and B-46.

[0101] The image recording layer may contain only one type of specific borate compound, or may contain two or more types. From the viewpoints of color development, color development over time after exposure, developability, and suppression of development defects over time in the resulting lithographic printing plate, the content of the specific borate compound is preferably 0.01% by mass to 30% by mass, more preferably 0.05% by mass to 25% by mass, and even more preferably 0.1% by mass to 20% by mass, in terms of the weight of the anion moiety of the specific borate compound, relative to the total mass of the image recording layer.

[0102] The specific borate compound may be a synthetic product. When preparing the specific borate compound by synthesis, in addition to the target borate compound, a borate compound with a different structure may be produced as a by-product. Furthermore, the obtained borate compound may contain small amounts of impurities derived from the solvent, catalyst, raw materials used, etc. According to the inventors' studies, even if the obtained borate compound contains at least one of a borate compound with a different structure from the target borate compound and impurities, the total content is small. Therefore, it has been confirmed that even if the synthesized borate compound is directly applied to an image recording layer coating liquid without undergoing a special purification step such as removing impurities, the performance of the resulting lithographic printing plate precursor is not affected.

[0103] Therefore, the image recording layer may contain at least one of borate compounds other than the specific borate compound and impurities unavoidable in the production process. Examples of at least one of borate compounds other than the specific borate compound and impurities unavoidable in the production process include raw materials used, solvents, catalysts, by-products generated by synthesis reactions, borate compounds other than the specific borate compound, etc.

[0104] <Electron-Accepting Polymerization Initiator> The image recording layer in Aspect A of the present disclosure contains an electron-accepting polymerization initiator. The image recording layer in Aspect B preferably contains an electron-accepting polymerization initiator. Note that the electron-accepting polymerization initiator contained in the image recording layer in Aspect B does not include the borate compound represented by Formula (1a). In one embodiment, the electron-accepting polymerization initiator is a compound that generates a polymerization initiating species such as a radical by accepting one electron through intermolecular electron transfer when electrons of an infrared absorber are excited by infrared exposure. The electron-accepting polymerization initiator used in the present disclosure is a compound that generates a polymerization initiating species such as a radical or a cation using the energy of light, heat, or both. Known thermal polymerization initiators, compounds having bonds with low bond dissociation energy, photopolymerization initiators, etc. can be appropriately selected and used. As the electron-accepting polymerization initiator, a radical polymerization initiator is preferred, and an onium salt compound is more preferred. As the electron-accepting polymerization initiator, an infrared-sensitive polymerization initiator is preferred. Examples of the electron-accepting radical polymerization initiator include (a) organic halides, (b) carbonyl compounds, (c) azo compounds, (d) organic peroxides, (e) metallocene compounds, (f) azide compounds, (g) hexaarylbiimidazole compounds, (i) disulfone compounds, (j) oxime ester compounds, and (k) onium salt compounds.

[0105] (a) Preferred examples of organic halides include the compounds described in paragraphs 0022 and 0023 of JP-A No. 2008-195018. (b) Preferred examples of carbonyl compounds include the compounds described in paragraph 0024 of JP-A No. 2008-195018. (c) Preferred examples of azo compounds include the azo compounds described in JP-A No. 8-108621. (d) Preferred examples of organic peroxides include the compounds described in paragraph 0025 of JP-A No. 2008-195018. (e) Preferred examples of metallocene compounds include the compounds described in paragraph 0026 of JP-A No. 2008-195018. (f) Preferred examples of azide compounds include 2,6-bis(4-azidobenzylidene)-4-methylcyclohexanone. Preferred examples of (g) hexaarylbiimidazole compounds include the compounds described in JP-A No. 2008-195018, paragraph 0027. Preferred examples of (i) disulfone compounds include the compounds described in JP-A Nos. 61-166544 and 2002-328465. Preferred examples of (j) oxime ester compounds include the compounds described in JP-A No. 2008-195018, paragraphs 0028 to 0030.

[0106] Among the electron-accepting polymerization initiators, preferred are oxime ester compounds and onium salt compounds from the viewpoint of curability. Among them, preferred are iodonium salt compounds, sulfonium salt compounds, and azinium salt compounds from the viewpoint of printing durability, more preferred are iodonium salt compounds or sulfonium salt compounds, and particularly preferred are iodonium salt compounds. Specific examples of these compounds are shown below, but the present disclosure is not limited thereto.

[0107] Preferred examples of iodonium salt compounds include diaryliodonium salt compounds, and more preferred are diphenyliodonium salt compounds substituted with electron-donating groups such as alkyl groups or alkoxy groups, and more preferred are asymmetric diphenyliodonium salt compounds. Specific examples include diphenyliodonium hexafluorophosphate, 4-methoxyphenyl-4-(2-methylpropyl)phenyliodonium hexafluorophosphate, 4-(2-methylpropyl)phenyl-p-tolyliodonium hexafluorophosphate, 4-hexyloxyphenyl-2,4,6-trimethoxyphenyliodonium hexafluorophosphate, 4-hexyloxyphenyl-2,4-diethoxyphenyliodonium tetrafluoroborate, 4-octyloxyphenyl-2,4,6-trimethoxyphenyliodonium 1-perfluorobutanesulfonate, 4-octyloxyphenyl-2,4,6-trimethoxyphenyliodonium hexafluorophosphate, and bis(4-t-butylphenyl)iodonium hexafluorophosphate.

[0108] Preferred examples of the sulfonium salt compound include triarylsulfonium salt compounds, particularly triarylsulfonium salt compounds in which electron-withdrawing groups, for example, at least a portion of the groups on the aromatic ring, are substituted with halogen atoms, and more preferred are triarylsulfonium salt compounds in which the total number of halogen atoms substituted on the aromatic ring is 4 or more. Specific examples include triphenylsulfonium hexafluorophosphate, triphenylsulfonium benzoylformate, bis(4-chlorophenyl)phenylsulfonium benzoylformate, bis(4-chlorophenyl)-4-methylphenylsulfonium tetrafluoroborate, tris(4-chlorophenyl)sulfonium 3,5-bis(methoxycarbonyl)benzenesulfonate, tris(4-chlorophenyl)sulfonium hexafluorophosphate, and tris(2,4-dichlorophenyl)sulfonium hexafluorophosphate.

[0109] Furthermore, as the counter anion of the iodonium salt compound and the sulfonium salt compound, a sulfonamide anion or a sulfonimide anion is preferred, and a sulfonimide anion is more preferred. As the sulfonamide anion, an arylsulfonamide anion is preferred. As the sulfonimide anion, a bisarylsulfonimide anion is preferred. Specific examples of sulfonamide anions or sulfonimide anions are shown below, but the present disclosure is not limited thereto. In the following specific examples, Ph represents a phenyl group, Me represents a methyl group, and Et represents an ethyl group.

[0110]

[0111] The electron-accepting polymerization initiator preferably contains a compound A represented by the following formula (Ia) and one or more compounds B selected from the group consisting of compounds represented by the following formula (Ib) or (Ic):

[0112]

[0113] In formulas (Ia) to (Ic), R １ , R ２ , R ３ , R ４ , R ５ and R ６ are each independently a substituted or unsubstituted alkyl group or a substituted or unsubstituted alkoxy group having 2 to 9 carbon atoms, and R ３ and R ４ At least one of １ or R ２ Unlike R １ and R ２ The total number of carbon atoms in ３ and R ４ the difference between the total number of carbon atoms in R is 0 to 4 (i.e., 0, 1, 2, 3, or 4); １ and R ２ The total number of carbon atoms in ５ and R ６ The difference between the total number of carbon atoms in X is 0 to 4. １ , X ２ and X ３ are the same or different anions.

[0114] The above R １ , R ２ , R ３ , R ４ , R ５ and R ６ are each independently preferably a substituted or unsubstituted alkyl group having 2 to 9 carbon atoms or a substituted or unsubstituted alkoxy group having 2 to 9 carbon atoms, more preferably a substituted or unsubstituted alkyl group having 3 to 6 carbon atoms or a substituted or unsubstituted alkoxy group having 3 to 6 carbon atoms, and even more preferably a substituted or unsubstituted alkyl group having 3 to 6 carbon atoms. The alkyl and alkoxy groups may be linear or branched, but are preferably branched. Examples of substituted or unsubstituted alkyl groups include ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, t-butyl, n-pentyl, t-pentyl, sec-pentyl, neopentyl, n-hexyl, isohexyl, sec-hexyl, t-hexyl, n-heptyl, n-octyl, isooctyl, 2-ethylhexyl, and n-nonyl. Examples of substituted or unsubstituted alkoxy groups include ethoxy, n-propoxy, isopropoxy, t-butoxy, n-butoxy, and n-octyloxy.

[0115] Above X １ , X ２ and X ３ Examples of the compound include ClO. ４ － , P.F. ６ － , B.F. ４ － , SbF ６ － , C.H. ３ SO ３ － , C.F. ３ SO ３ － , C ６ H ５ SO ３ － , C.H. ３ C ６ H４ SO ３ － , H.O.C. ６ H ４ SO ３ － , ClC ６ H ４ SO ３ － and borate anions represented by the following structure (Id):

[0116] B － (R １ ) (R ２ ) (R ３ ) (R ４ ) Formula (Id)

[0117] In formula (Id), R １ , R ２ , R ３ and R ４ R each independently represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group (including a halogen-substituted aryl group), a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted cycloalkyl group, or a substituted or unsubstituted heterocyclic group. １ , R ２ , R ３ and R ４ Two or more of R may be linked together to form a substituted or unsubstituted heterocycle containing a boron atom. The resulting heterocycle has up to seven carbon atoms, nitrogen atoms, oxygen atoms, or nitrogen atoms. １ , R ２ , R ３ and R ４ The substituent in the formula (I) may be a chlorine atom, a fluorine atom, a nitro group, an alkyl group, an alkoxy group, or an acetoxy group.

[0118] The above R １ , R ２ , R ３ and R ４ Preferably, all of the groups are substituted or unsubstituted aryl groups, and more preferably all are unsubstituted phenyl groups.

[0119] Above X １ , X ２ and X３ Preferably, at least one of X is a tetraarylborate anion containing the same or different aryl groups, and more preferably, one or more of X is a tetraphenylborate anion; １ , X ２ and X ３ More preferably, each of is a tetraphenylborate anion.

[0120] In a preferred embodiment, compound B comprises a compound represented by formula (Ic), and R １ is R ５ is the same as R ２ is R ６ In particular, R １ is R ２ is the same as, for example, R １ and R ２ are preferably iso-propyl, iso-butyl, or t-butyl groups.

[0121] In another preferred embodiment, compound B includes a compound represented by formula (Ib), and R １ is R ２ is the same as R ３ is R ４ In this case, R １ and R ２ Preferably, both of R are isopropyl, isobutyl, or t-butyl groups. １ and R ３ The difference in the number of carbon atoms between is preferably 1 or 2.

[0122] Compound B may be a mixture of a compound represented by formula (Ib) and a compound represented by formula (Ic).

[0123] The compounds represented by formula (Ia) to formula (Ic) may be obtained from Sigma-Aldrich or the like, or may be synthesized using known synthetic methods and readily available starting materials.

[0124] The molar ratio of compound A to compound B is preferably 10:90 to 90:10, more preferably 20:80 to 80:20, and even more preferably 30:70 to 70:30.

[0125] Furthermore, from the viewpoints of developability and printing durability of the resulting lithographic printing plate, the electron-accepting polymerization initiator may contain a compound represented by formula (II) described in paragraphs 0186 to 0197 of WO 2022 / 019217.

[0126] The lowest unoccupied molecular orbital (LUMO) of the electron-accepting polymerization initiator is preferably −3.00 eV or less, more preferably −3.02 eV or less, from the viewpoint of improving sensitivity and preventing plate skipping. The lower limit is preferably −3.80 eV or more, more preferably −3.60 eV or more.

[0127] The electron-accepting polymerization initiator may be used alone or in combination of two or more. The content of the electron-accepting polymerization initiator is preferably 0.1% by mass to 50% by mass, more preferably 0.5% by mass to 30% by mass, and particularly preferably 0.8% by mass to 20% by mass, based on the total mass of the image recording layer.

[0128] <Infrared absorber> The image recording layer of the present disclosure preferably contains an infrared absorber. The infrared absorber is not particularly limited, and examples thereof include pigments and dyes. As the dye used as the infrared absorber, commercially available dyes and known dyes described in literature such as "Dye Handbook" (edited by the Society of Organic Synthetic Chemistry, published in 1970) can be used. Specific examples of the dye include azo dyes, metal complex azo dyes, pyrazolone azo dyes, naphthoquinone dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinoneimine dyes, methine dyes, cyanine dyes, squarylium dyes, pyrylium salts, and metal thiolate complex dyes.

[0129] Particularly preferred of these dyes are cyanine dyes, squarylium dyes, pyrylium salts, nickel thiolate complexes, and indolenine cyanine dyes. Furthermore, cyanine dyes and indolenine cyanine dyes are also preferred. Of these, cyanine dyes are particularly preferred.

[0130] The infrared absorber is preferably a cationic polymethine dye having an oxygen or nitrogen atom at the meso position. Preferred examples of the cationic polymethine dye include cyanine dyes, pyrylium dyes, thiopyrylium dyes, and azulenium dyes. From the viewpoints of availability, solvent solubility during the introduction reaction, and the like, cyanine dyes are preferred.

[0131] Specific examples of cyanine dyes include the compounds described in paragraphs 0017 to 0019 of JP-A-2001-133969, the compounds described in paragraphs 0016 to 0021 of JP-A-2002-023360, and the compounds described in paragraphs 0012 to 0037 of JP-A-2002-040638, preferably the compounds described in paragraphs 0034 to 0041 of JP-A-2002-278057 and paragraphs 0080 to 0086 of JP-A-2008-195018, and particularly preferably the compounds described in paragraphs 0035 to 0043 of JP-A-2007-90850, and the compounds described in paragraphs 0105 to 0113 of JP-A-2012-206495. In addition, the compounds described in paragraphs 0008 to 0009 of JP-A No. 5-5005 and paragraphs 0022 to 0025 of JP-A No. 2001-222101 can also be preferably used. As the pigment, the compounds described in paragraphs 0072 to 0076 of JP-A No. 2008-195018 are preferred.

[0132] Furthermore, the infrared absorber preferably contains an infrared absorber that decomposes upon exposure to infrared rays (decomposable infrared absorber), and more preferably contains a decomposable color-forming infrared absorber. It is presumed that by using a decomposable infrared absorber as the infrared absorber, the infrared absorber or its decomposition products promote polymerization, and the decomposition products of the infrared absorber interact with the polymerizable compound, resulting in excellent printing durability. The decomposable infrared absorber is preferably an infrared absorber that has the function of absorbing infrared rays, decomposing, and developing a color upon infrared exposure. Hereinafter, a color-developed compound formed by the decomposable infrared absorber absorbing infrared rays and decomposing upon infrared exposure is also referred to as a "color-forming body of the decomposable infrared absorber." Furthermore, the decomposable infrared absorber preferably has the function of absorbing infrared rays upon infrared exposure and converting the absorbed infrared rays into heat. The decomposable infrared absorbent may be any that absorbs and decomposes at least a portion of light in the infrared wavelength region (wavelength 750 nm to 1 mm), but is preferably an infrared absorbent having a maximum absorption wavelength in the wavelength region of 750 nm to 1,400 nm, and more preferably an infrared absorbent having a maximum absorption wavelength in the wavelength region of 760 nm to 900 nm. More specifically, the decomposable infrared absorbent is preferably a compound that decomposes due to exposure to infrared light to produce a compound having a maximum absorption wavelength in the wavelength region of 500 nm to 600 nm.

[0133] The decomposable infrared absorber is preferably an infrared absorber that decomposes due to heat, electron transfer, or both caused by infrared exposure, and more preferably an infrared absorber that decomposes due to electron transfer caused by infrared exposure. Here, "decomposes due to electron transfer" means that electrons excited from the HOMO (highest occupied molecular orbital) to the LUMO (lowest unoccupied molecular orbital) of the decomposable infrared absorber by infrared exposure undergo intramolecular electron transfer to an electron-accepting group in the molecule (for example, a group having a potential close to that of the LUMO), resulting in decomposition.

[0134] The infrared absorber preferably contains a compound represented by the following formula 1:

[0135]

[0136] In formula 1, R１ and R ２ each independently represents a hydrogen atom or an alkyl group; R １ and R ２ may be linked to each other to form a ring, R ３ ~R ６ each independently represents a hydrogen atom or an alkyl group; R ７ and R ８ each independently represents an alkyl group or an aryl group; Y １ and Y ２ are each independently an oxygen atom, a sulfur atom, or —NR ０ - or a dialkylmethylene group, R ０ represents a hydrogen atom, an alkyl group, or an aryl group; Ar １ and Ar ２ each independently represents a group forming a benzene ring or a naphthalene ring which may have a group represented by the formula 2 described below; A １ is -NR ９ R １０ , -X １ -L １ or a group represented by formula 2 described below, R ９ and R １０ each independently represents an alkyl group, an aryl group, an alkoxycarbonyl group, or an arylsulfonyl group; X １ represents an oxygen atom or a sulfur atom, L １ is a hydrocarbon group, a heteroaryl group, or a group that is converted by heat or infrared exposure to X １ represents a group that cleaves the bond with Ar; Za represents a counter ion that neutralizes the charge; １ and Ar ２ At least one of the above has a group represented by the following formula 2: -X Formula 2 In formula 2, X is a halogen atom, -C(=O)-X ２ -R １１ , -C(=O)-NR １２ R １３ , -OC(=O)-R １４ , -CN, -SO ２ NR １５ R １６ or a perfluoroalkyl group, X ２ represents a single bond or an oxygen atom, R １１ and R１４ each independently represents an alkyl group or an aryl group; R １２ , R １３ , R １５ and R １６ each independently represents a hydrogen atom, an alkyl group, or an aryl group.

[0137] Ar １ and Ar ２ Each of Ar independently represents a group forming a benzene ring or a naphthalene ring. The benzene ring and the naphthalene ring may have a substituent other than -X. Examples of the substituent include an alkyl group, an alkoxy group, an aryloxy group, an amino group, an alkylthio group, an arylthio group, a carboxy group, a carboxylate group, a sulfo group, a sulfonate group, and a group formed by combining these groups, but an alkyl group is preferred. In addition, in Formula 1, Ar １ and Ar ２ and from the viewpoint of printing durability and visibility, １ and Ar ２ It is preferable that both of the above have a group represented by formula 2.

[0138] X in formula 2 is a halogen atom, —C(═O)—X ２ -R １１ , -C(=O)-NR １２ R １３ , -OC(=O)-R １４ , -CN, -SO ２ NR １５ R １６ or a perfluoroalkyl group, and from the viewpoints of printing durability, visibility, and stability over time, a halogen atom, —C(═O)—X ２ -R １１ , -C(=O)-NR １２ R １３ , -OC(=O)-R １４ , CN, or -SO ２ NR １５ R １６ is preferably a halogen atom, —C(═O)—O—R １１ , -C(=O)-NR １２ R １３ , or —O—C(═O)—R１４ is preferably a halogen atom, —C(═O)—O—R １１ , or —O—C(═O)—R １４ It is more preferable that the group is a fluorine atom, a chlorine atom, a bromine atom, or —C(═O)OR １７ is particularly preferred, and a chlorine atom or a bromine atom is most preferred.

[0139] X ２ represents a single bond or an oxygen atom, and is preferably an oxygen atom. １１ and R １４ R each independently represents an alkyl group or an aryl group, and is preferably an alkyl group having 1 to 12 carbon atoms or an aryl group having 6 to 12 carbon atoms, and more preferably an alkyl group having 1 to 12 carbon atoms. １２ , R １３ , R １５ and R １６ R each independently represents a hydrogen atom, an alkyl group, or an aryl group, and is preferably a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, or an aryl group having 6 to 12 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 to 12 carbon atoms, and even more preferably an alkyl group having 1 to 12 carbon atoms. １７ represents an alkyl group or an aryl group, preferably an alkyl group having 1 to 12 carbon atoms or an aryl group having 6 to 12 carbon atoms, and more preferably an alkyl group having 1 to 12 carbon atoms.

[0140] A １ is -NR ９ R １０ , -X １ -L １ or -X, and from the viewpoint of printing durability, visibility and stability over time, -NR ９ R １０ or -X １ -L １ Preferably, —NR １８ R １９ , -S-R ２０ It is more preferable that A １From the viewpoints of plate skip suppression, GLV suitability and printing durability, R is preferably —X, more preferably a halogen atom, further preferably a chlorine atom or a bromine atom, and particularly preferably a chlorine atom. ９ and R １０ Each of X independently represents an alkyl group, an aryl group, an alkoxycarbonyl group, or an arylsulfonyl group, and is preferably an alkyl group having 1 to 12 carbon atoms or an aryl group having 6 to 12 carbon atoms, more preferably an alkyl group having 1 to 12 carbon atoms. １ represents an oxygen atom or a sulfur atom, L １ When L is a hydrocarbon group or a heteroaryl group, it is preferably a sulfur atom. １ X is converted by heat or infrared exposure １ It is preferable that the bond between L and １ is a hydrocarbon group, a heteroaryl group, or a group that is converted by heat or infrared exposure to X １ From the viewpoint of printing durability, a hydrocarbon group or a heteroaryl group is preferable, an aryl group or a heteroaryl group is more preferable, and a heteroaryl group is even more preferable. １ From the viewpoint of visibility and prevention of fading over time, X-rays are １ A group in which the bond to X is cleaved by heat or infrared exposure is preferred. １ The group that cleaves the bond with R will be described later. １８ and R １９ R each independently represents an aryl group, preferably an aryl group having 6 to 20 carbon atoms, and more preferably a phenyl group. ２０ represents a hydrocarbon group or a heteroaryl group, preferably an aryl group or a heteroaryl group, and more preferably a heteroaryl group.

[0141] L １ and R ２０ Preferred examples of the heteroaryl group in the formula include the following groups:

[0142]

[0143] R１ ~R １０ , and R ０ The alkyl group in the formula (I) is preferably an alkyl group having 1 to 30 carbon atoms, more preferably an alkyl group having 1 to 15 carbon atoms, and even more preferably an alkyl group having 1 to 10 carbon atoms. The alkyl group may be linear, branched, or have a cyclic structure. Specific examples include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, hexadecyl, octadecyl, eicosyl, isopropyl, isobutyl, s-butyl, t-butyl, isopentyl, neopentyl, 1-methylbutyl, isohexyl, 2-ethylhexyl, 2-methylhexyl, cyclohexyl, cyclopentyl, and 2-norbornyl. Of these alkyl groups, methyl, ethyl, propyl, and butyl are particularly preferred.

[0144] The alkyl group may have a substituent, such as an alkoxy group, an aryloxy group, an amino group, an alkylthio group, an arylthio group, a halogen atom, a carboxy group, a carboxylate group, a sulfo group, a sulfonate group, an alkyloxycarbonyl group, an aryloxycarbonyl group, or a combination thereof.

[0145] R ９ , R １０ , R １８ , R １９ and R ０The aryl group in (I) is preferably an aryl group having 6 to 30 carbon atoms, more preferably an aryl group having 6 to 20 carbon atoms, and even more preferably an aryl group having 6 to 12 carbon atoms. The aryl group may have a substituent. Examples of the substituent include an alkyl group, an alkoxy group, an aryloxy group, an amino group, an alkylthio group, an arylthio group, a halogen atom, a carboxy group, a carboxylate group, a sulfo group, a sulfonate group, an alkyloxycarbonyl group, an aryloxycarbonyl group, and combinations thereof. Specific examples of the aryl group include a phenyl group, a naphthyl group, a p-tolyl group, a p-chlorophenyl group, a p-fluorophenyl group, a p-methoxyphenyl group, a p-dimethylaminophenyl group, a p-methylthiophenyl group, and a p-phenylthiophenyl group. Of these aryl groups, a phenyl group, a p-methoxyphenyl group, a p-dimethylaminophenyl group, or a naphthyl group is preferred.

[0146] R １ and R ２ are preferably linked to form a ring. １ and R ２ When R are linked to form a ring, the number of ring members is preferably 5 or 6, and more preferably 6. １ and R ２ The ring formed by linking the groups is preferably a hydrocarbon ring which may have an ethylenically unsaturated bond.

[0147] Y １ and Y ２ are each independently an oxygen atom, a sulfur atom, or —NR ０ represents - or a dialkylmethylene group, -NR ０ - or a dialkylmethylene group is preferred, and a dialkylmethylene group is more preferred. ０ represents a hydrogen atom, an alkyl group or an aryl group, and is preferably an alkyl group.

[0148] R ７ and R ８ are preferably the same group. ７ and R ８are each independently preferably a linear alkyl group or an alkyl group having a terminal sulfonate group, and more preferably a methyl group, an ethyl group, or a butyl group having a terminal sulfonate group. The counter cation of the sulfonate group may be a cation on the nitrogen atom in Formula 1, or may be an alkali metal cation or an alkaline earth metal cation. Furthermore, from the viewpoint of improving the water solubility of the compound represented by Formula 1, R ７ and R ８ are each independently preferably an alkyl group having an anionic structure, more preferably an alkyl group having a carboxylate group or a sulfonate group, and even more preferably an alkyl group having a sulfonate group at the terminal. ７ and R ８ are each independently preferably an alkyl group having an aromatic ring, more preferably an alkyl group having an aromatic ring at a terminal, and particularly preferably a 2-phenylethyl group, a 2-naphthalenylethyl group, or a 2-(9-anthracenyl)ethyl group.

[0149] R ３ ~R ６ each independently represents a hydrogen atom or an alkyl group, and is preferably a hydrogen atom.

[0150] In addition, the compound represented by formula 1 preferably has one or more halogen atoms from the viewpoint of stability over time and printing durability. １ , Ar １ and Ar ２ It is more preferable that at least one selected from the group consisting of has one or more halogen atoms, and A １ , Ar １ and Ar ２It is particularly preferred that each of Ar has one or more halogen atoms. Furthermore, from the viewpoint of stability over time and printing durability, the compound represented by formula 1 more preferably has two or more halogen atoms, even more preferably has three or more halogen atoms, and particularly preferably has three to six halogen atoms. Furthermore, preferred examples of the halogen atom include a chlorine atom or a bromine atom. Furthermore, from the viewpoint of stability over time and printing durability, the compound represented by formula 1 １ and Ar ２ At least one of Ar and Ar preferably has a halogen atom. １ and Ar ２ It is more preferable that at least one of Ar has a chlorine atom or a bromine atom. １ and Ar ２ It is particularly preferred that at least one of them has a bromine atom.

[0151] Za represents a counter ion that neutralizes the charge, and when Za represents an anion species, examples thereof include a sulfonate ion, a carboxylate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, a perchlorate ion, a sulfonamide anion, and a sulfonimide anion. When Za represents a cation species, an alkali metal ion, an alkaline earth metal ion, an ammonium ion, a pyridinium ion, or a sulfonium ion is preferred, a sodium ion, a potassium ion, an ammonium ion, a pyridinium ion, or a sulfonium ion is more preferred, a sodium ion, a potassium ion, or an ammonium ion is even more preferred, and a sodium ion, a potassium ion, or a trialkylammonium ion is particularly preferred. Among these, Za is preferably an organic anion containing a carbon atom from the viewpoint of printing durability and visibility, more preferably a sulfonate ion, a carboxylate ion, a sulfonamide anion, or a sulfonimide anion, more preferably a sulfonamide anion or a sulfonimide anion, and particularly preferably a sulfonimide anion. R １ ~R ８ , R ０ , A １ , Ar １, Ar ２ , Y １ and Y ２ may have an anionic structure or a cationic structure, and R １ ~R ８ , R ０ , A １ , Ar １ , Ar ２ , Y １ and Y ２ If all of R are charge-neutral groups, Za is a monovalent counter anion. １ ~R ８ , R ０ , A １ , Ar １ , Ar ２ , Y １ and Y ２ In the case where the compound has two or more anionic structures, Za can also serve as a counter cation. In addition, in Formula 1, Za may be omitted if the moieties other than Za are neutral in charge.

[0152] The sulfonamide anion is preferably an arylsulfonamide anion. Furthermore, the sulfonimide anion is preferably a bisarylsulfonimide anion. Specific examples of sulfonamide anions or sulfonimide anions are shown below, but the present disclosure is not limited thereto. In the following specific examples, Ph represents a phenyl group, Me represents a methyl group, and Et represents an ethyl group.

[0153]

[0154] The above-mentioned heat or infrared exposure causes X １ From the viewpoint of visibility, the group whose bond with is cleaved is preferably a group represented by any one of the following formulas (1-1) to (1-7), and more preferably a group represented by any one of the following formulas (1-1) to (1-3).

[0155]

[0156] In formulas (1-1) to (1-7), ● represents X in formula 1. １ represents the binding site with １０ are each independently a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, or —OR１４ , -NR １５ R １６ or -SR １７ represents R １１ each independently represents a hydrogen atom, an alkyl group, or an aryl group; R １２ is an aryl group, —OR １４ , -NR １５ R １６ , -SR １７ , -C(=O)R １８ , -OC(=O)R １８ or a halogen atom, R １３ represents an aryl group, an alkenyl group, an alkoxy group, or an onium group; R １４ ~R １７ each independently represents a hydrogen atom, an alkyl group, or an aryl group; R １８ are each independently an alkyl group, an aryl group, or —OR １４ , -NR １５ R １６ or -SR １７ represents Z １ represents a counter ion that neutralizes the charge.

[0157] R １０ , R １１ and R １４ ~R １８ In a preferred embodiment, when R is an alkyl group, ２ ~R ９ and R ０ The preferred embodiments of the alkyl group in R １０ and R １３ The number of carbon atoms in the alkenyl group in R is preferably 1 to 30, more preferably 1 to 15, and even more preferably 1 to 10. １０ ~R １８ In a preferred embodiment, when R is an aryl group, ０ The preferred embodiments are the same as those of the aryl group in the above.

[0158] From the viewpoint of visibility, R in formula (1-1) １０ represents an alkyl group, an alkenyl group, an aryl group, -OR １４ , -NR １５ R １６ or -SR １７is preferably an alkyl group, —OR １４ , -NR １５ R １６ or -SR １７ More preferably, it is an alkyl group or —OR １４ More preferably, -OR １４ It is particularly preferable that R in formula (1-1) is １０ When R is an alkyl group, the alkyl group is preferably an alkyl group having an arylthio group or an alkyloxycarbonyl group at the α-position. １０ Ga-OR １４ If R １４ is preferably an alkyl group, more preferably an alkyl group having 1 to 8 carbon atoms, further preferably an isopropyl group or a t-butyl group, and particularly preferably a t-butyl group.

[0159] From the viewpoint of visibility, R in formula (1-2) １１ is preferably a hydrogen atom. １２ is -C(=O)OR １４ , -OC(=O)OR １４ or a halogen atom, and —C(═O)OR １４ or -OC(=O)OR １４ It is more preferable that R in formula (1-2) is １２ -C(=O)OR １４ or -OC(=O)OR １４ If R １４ is preferably an alkyl group.

[0160] From the viewpoint of visibility, R in formula (1-3) １１ are each independently preferably a hydrogen atom or an alkyl group, and at least one R １１ is more preferably an alkyl group. １１ The alkyl group in R is preferably an alkyl group having 1 to 10 carbon atoms, and more preferably an alkyl group having 3 to 10 carbon atoms. １１The alkyl group in formula (1-3) is preferably a branched alkyl group or a cycloalkyl group, more preferably a secondary or tertiary alkyl group or a cycloalkyl group, and even more preferably an isopropyl group, a cyclopentyl group, a cyclohexyl group, or a t-butyl group. １３ is preferably an aryl group, an alkoxy group, or an onium group, more preferably a p-dimethylaminophenyl group or a pyridinium group, and even more preferably a pyridinium group. １３ Examples of the onium group in the formula (I) include a pyridinium group, an ammonium group, and a sulfonium group. The onium group may have a substituent. Examples of the substituent include an alkyl group, an alkoxy group, an aryloxy group, an amino group, an alkylthio group, an arylthio group, a halogen atom, a carboxy group, a sulfo group, an alkyloxycarbonyl group, an aryloxycarbonyl group, and a group formed by combining these groups. However, an alkyl group, an aryl group, or a group formed by combining these groups is preferred. Among these, a pyridinium group is preferred, and examples thereof include an N-alkyl-3-pyridinium group, an N-benzyl-3-pyridinium group, an N-(alkoxypolyalkyleneoxyalkyl)-3-pyridinium group, an N-alkoxycarbonylmethyl-3-pyridinium group, an N-alkyl-4-pyridinium group, an N-benzyl-4-pyridinium group, an N-(alkoxypolyalkyleneoxyalkyl)-4-pyridinium group, and an N-alkoxycarbonylmethyl-4-pyridinium group. An N-methyl-3-pyridinium group, an N-octyl-3-pyridinium group, an N-methyl-4-pyridinium group, or an N-octyl-4-pyridinium group is particularly preferred, and an N-octyl-3-pyridinium group or an N-octyl-4-pyridinium group is most preferred. １３is a pyridinium group, examples of the counter anion include a sulfonate ion, a carboxylate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, a p-toluenesulfonate ion, a perchlorate ion, and the like, with a p-toluenesulfonate ion or a hexafluorophosphate ion being preferred.

[0161] From the viewpoint of visibility, R in formula (1-4) １０ is preferably an alkyl group or an aryl group, and two R １０ In terms of visibility, it is more preferable that one of the R groups in formula (1-5) is an alkyl group and the other is an aryl group. １０ is preferably an alkyl group or an aryl group, more preferably an aryl group, and further preferably a p-methylphenyl group. １０ are each independently preferably an alkyl group or an aryl group, more preferably a methyl group or a phenyl group. １ is a counter ion that neutralizes the charge, and the compound as a whole may be included in the above Za. １ is preferably a sulfonate ion, a carboxylate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, a p-toluenesulfonate ion, or a perchlorate ion, and more preferably a p-toluenesulfonate ion or a hexafluorophosphate ion.

[0162] In addition, the above-mentioned heat or infrared exposure １ The group whose bond with is cleaved is particularly preferably a group represented by formula (1-8).

[0163]

[0164] In formula (1-8), ● represents X in formula 1. １ represents the binding site with １９ and R ２０ each independently represents an alkyl group, and Za' represents a counter ion that neutralizes the charge.

[0165] The pyridinium ring and R in formula (1-8) ２０ The bonding position to the hydrocarbon group containing R is preferably the 3- or 4-position of the pyridinium ring, and more preferably the 4-position of the pyridinium ring. １９ and R ２０ The alkyl group in R may be linear, branched, or have a ring structure. The alkyl group may have a substituent, and preferred examples of the substituent include an alkoxy group and a terminal alkoxypolyalkyleneoxy group. １９ is preferably an alkyl group having 1 to 12 carbon atoms, more preferably a linear alkyl group having 1 to 12 carbon atoms, even more preferably a linear alkyl group having 1 to 8 carbon atoms, and particularly preferably a methyl group or an n-octyl group. ２０ is preferably an alkyl group having 1 to 8 carbon atoms, more preferably a branched alkyl group having 3 to 8 carbon atoms, further preferably an isopropyl group or a t-butyl group, and particularly preferably an isopropyl group. Za' may be any counter ion that neutralizes the charge, and the entire compound may be included in the above Za. Za' is preferably a sulfonate ion, a carboxylate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, a p-toluenesulfonate ion, or a perchlorate ion, and more preferably a p-toluenesulfonate ion or a hexafluorophosphate ion.

[0166] In addition, from the viewpoint of enhancing the visibility of the exposed area, the decomposable infrared absorber is preferably a group that decomposes upon exposure to infrared light (specifically, R １ From the viewpoint of improving the visibility of the exposed area, the decomposable infrared absorber is more preferably a compound represented by the following formula 1-1:

[0167]

[0168] In formula 1-1, R １ represents a group represented by any one of the following formulas 2-1 to 4-1, and R１１ ~R １８ are each independently a hydrogen atom, a halogen atom, or —R ａ , -OR ｂ , -SR ｃ , or -NR ｄ R ｅ represents R ａ ~R ｅ each independently represents a hydrocarbon group; A １ , A ２ and multiple R １１ ~R １８ may be linked to form a monocyclic or polycyclic ring, A １ and A ２ each independently represents an oxygen atom, a sulfur atom, or a nitrogen atom; n １１ and n １２ each independently represents an integer of 0 to 5, provided that n １１ and n １２ The sum of n is 2 or more, １３ and n １４ each independently represents 0 or 1, and L represents an oxygen atom, a sulfur atom, or —NR １０ represents -, and R １０ represents a hydrogen atom, an alkyl group, or an aryl group, and Za represents a counter ion that neutralizes the charge.

[0169]

[0170] In formulas 2-1 to 4-1, R ２０ , R ３０ , R ４１ and R ４２ each independently represents an alkyl group or an aryl group, Zb represents a counter ion that neutralizes the charge, and the wavy line represents the bonding site with the group represented by L in the above formula 1-1.

[0171] When the compound of formula 1-1 is exposed to infrared light, R １ The -L bond is cleaved and L is ═O, ═S, or ═NR １０ and discoloration occurs.

[0172] In Formula 1-1, R １represents a group represented by any one of the above formulas 2-1 to 4-1. The group represented by formula 2-1, the group represented by formula 3-1, and the group represented by formula 4-1 will be explained below.

[0173] In formula 2-1, R ２０ represents an alkyl group or an aryl group, and the wavy line portion represents the bonding site with the group represented by L in Formula 1-1. ２０ The alkyl group represented by the formula (I) is preferably an alkyl group having 1 to 30 carbon atoms, more preferably an alkyl group having 1 to 15 carbon atoms, and even more preferably an alkyl group having 1 to 10 carbon atoms. The alkyl group may be linear, branched, or have a ring structure. ２０ The aryl group represented by the formula (I) is preferably an aryl group having 6 to 30 carbon atoms, more preferably an aryl group having 6 to 20 carbon atoms, and even more preferably an aryl group having 6 to 12 carbon atoms. ２０ From the viewpoint of visibility, the group is preferably an alkyl group.

[0174] In addition, from the viewpoint of decomposability and visibility, R ２０ The alkyl group represented by R is preferably a secondary alkyl group or a tertiary alkyl group, and more preferably a tertiary alkyl group. ２０ The alkyl group represented by the formula (I) is preferably an alkyl group having 1 to 8 carbon atoms, more preferably a branched alkyl group having 3 to 10 carbon atoms, and even more preferably a branched alkyl group having 3 to 6 carbon atoms, and is particularly preferably an isopropyl group or a tert-butyl group, and most preferably a tert-butyl group.

[0175] Specific examples of the group represented by formula 2-1 above are listed below, but the present disclosure is not limited to these. In the following structural formula, ● represents the bonding site with the group represented by L in formula 1-1.

[0176]

[0177] In formula 3-1, R ３０ represents an alkyl group or an aryl group, and the wavy line portion represents the bonding site with the group represented by L in Formula 1-1.３０ The alkyl group and aryl group represented by the formula 2-1 are R ２０ The same applies to the alkyl and aryl groups represented by the following formula (1), and the preferred embodiments are also the same.

[0178] From the viewpoint of decomposability and visibility, ３０ The alkyl group represented by R is preferably a secondary alkyl group or a tertiary alkyl group, and more preferably a tertiary alkyl group. ３０ The alkyl group represented by R is preferably an alkyl group having 1 to 8 carbon atoms, more preferably a branched alkyl group having 3 to 10 carbon atoms, and even more preferably a branched alkyl group having 3 to 6 carbon atoms, and is particularly preferably an isopropyl group or a tert-butyl group, with a tert-butyl group being most preferred. Furthermore, from the viewpoints of decomposability and visibility, R ３０ The alkyl group represented by the formula (I) is preferably a substituted alkyl group, more preferably a fluoro-substituted alkyl group, further preferably a perfluoroalkyl group, and particularly preferably a trifluoromethyl group.

[0179] From the viewpoint of decomposability and visibility, ３０ The aryl group represented by the formula (I) is preferably a substituted aryl group, and examples of the substituent include an alkyl group (preferably an alkyl group having 1 to 4 carbon atoms) and an alkoxy group (preferably an alkoxy group having 1 to 4 carbon atoms).

[0180] Specific examples of the group represented by formula 3-1 above are listed below, but the present disclosure is not limited to these. In the following structural formula, ● represents the bonding site with the group represented by L in formula 1-1.

[0181]

[0182] In formula 4-1, R ４１ and R ４２ each independently represents an alkyl group or an aryl group, Zb represents a counter ion that neutralizes the charge, and the wavy line represents the bonding site with the group represented by L in Formula 1-1. ４１ or R ４２The alkyl group and aryl group represented by the formula 2-1 are R ２０ The preferred embodiments are the same as those of the alkyl and aryl groups represented by R ４１ From the viewpoints of decomposability and visibility, R is preferably an alkyl group. ４２ From the viewpoints of decomposability and visibility, the group is preferably an alkyl group.

[0183] From the viewpoint of decomposability and visibility, ４１ The alkyl group represented by R is preferably an alkyl group having 1 to 8 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms, and particularly preferably a methyl group. ４２ The alkyl group represented by R is preferably a secondary alkyl group or a tertiary alkyl group, and more preferably a tertiary alkyl group. ４２ The alkyl group represented by the formula (I) is preferably an alkyl group having 1 to 8 carbon atoms, more preferably a branched alkyl group having 3 to 10 carbon atoms, and even more preferably a branched alkyl group having 3 to 6 carbon atoms, and is particularly preferably an isopropyl group or a tert-butyl group, and most preferably a tert-butyl group.

[0184] Zb in Formula 4-1 may be any counter ion for neutralizing the charge, and the entire compound may be included in Za in Formula 1-1. Zb is preferably a sulfonate ion, a carboxylate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, a p-toluenesulfonate ion, or a perchlorate ion, and more preferably a tetrafluoroborate ion or a hexafluorophosphate ion.

[0185] Specific examples of the group represented by formula 4-1 above are listed below, but the present disclosure is not limited to these. In the following structural formula, ● represents the bonding site with the group represented by L in formula 1-1.

[0186]

[0187] In formula 1-1, L is an oxygen atom or —NR １０ - is preferred, and an oxygen atom is particularly preferred. １０ R in - １０ is preferably an alkyl group. １０ The alkyl group represented by R is preferably an alkyl group having 1 to 10 carbon atoms. １０ The alkyl group represented by the formula (I) may be linear, branched, or have a ring structure. Among the alkyl groups, a methyl group or a cyclohexyl group is preferred. １０ R in - １０ When is an aryl group, it is preferably an aryl group having 6 to 30 carbon atoms, more preferably an aryl group having 6 to 20 carbon atoms, and even more preferably an aryl group having 6 to 12 carbon atoms. These aryl groups may have a substituent.

[0188] In Formula 1-1, R １１ ~R １８ are each independently a hydrogen atom, -R ａ , -OR ｂ , -SR ｃ , or -NR ｄ R ｅ It is preferable that R ａ ~R ｅ The hydrocarbon group represented by the formula (I) is preferably a hydrocarbon group having 1 to 30 carbon atoms, more preferably a hydrocarbon group having 1 to 15 carbon atoms, and even more preferably a hydrocarbon group having 1 to 10 carbon atoms. The hydrocarbon group may be linear, branched, or have a cyclic structure. As the hydrocarbon group, an alkyl group is particularly preferred.

[0189] The alkyl group is preferably an alkyl group having 1 to 30 carbon atoms, more preferably an alkyl group having 1 to 15 carbon atoms, and even more preferably an alkyl group having 1 to 10 carbon atoms. The alkyl group may be linear, branched, or have a cyclic structure. Specific examples include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, a hexadecyl group, an octadecyl group, an eicosyl group, an isopropyl group, an isobutyl group, a s-butyl group, a tert-butyl group, an isopentyl group, a neopentyl group, a 1-methylbutyl group, an isohexyl group, a 2-ethylhexyl group, a 2-methylhexyl group, a cyclohexyl group, a cyclopentyl group, and a 2-norbornyl group. Of the alkyl groups, a methyl group, an ethyl group, a propyl group, or a butyl group is preferred.

[0190] The alkyl group may have a substituent, and examples of the substituent include an alkoxy group, an aryloxy group, an amino group, an alkylthio group, an arylthio group, a halogen atom, a carboxy group, a carboxylate group, a sulfo group, a sulfonate group, an alkyloxycarbonyl group, an aryloxycarbonyl group, and combinations thereof.

[0191] R in Formula 1-1 １１ ~R １４ are each independently a hydrogen atom or -R ａ (i.e., a hydrocarbon group), more preferably a hydrogen atom or an alkyl group, and even more preferably a hydrogen atom, except in the following cases. １１ and R １３ is preferably an alkyl group, and more preferably both groups are bonded to form a ring. The ring formed may be a monocyclic ring or a polycyclic ring. Specific examples of the ring formed include monocyclic rings such as a cyclopentene ring, a cyclopentadiene ring, a cyclohexene ring, and a cyclohexadiene ring, and polycyclic rings such as an indene ring and an indole ring. １ ＋R bonded to the carbon atom to which １２ is R １５ or R １６ (Preferably R １６ ) to form a ring, and A ２ R bonded to the carbon atom to which １４ is R １７ or R １８ (Preferably R １８ ) to form a ring.

[0192] In Formula 1-1, n １３ is 1, and R １６ is -R ａ (i.e., a hydrocarbon group). １６ A １ ＋ R bonded to the carbon atom to which １２ It is preferable that n is linked to form a ring. The ring formed is preferably an indolium ring, a pyrylium ring, a thiopyrylium ring, a benzoxazoline ring, or a benzimidazoline ring, and from the viewpoint of improving the visibility of the exposed area, an indolium ring is more preferable. These rings may further have a substituent. In Formula 1-1, n １４ is 1, and R １８ is -R ａ (i.e., a hydrocarbon group). １８ A ２ R bonded to the carbon atom to which １４ It is preferable that R in Formula 1-1 is linked to form a ring. The ring formed is preferably an indole ring, a pyran ring, a thiopyran ring, a benzoxazole ring, or a benzimidazole ring, and from the viewpoint of improving the visibility of the exposed area, an indole ring is more preferable. These rings may further have a substituent. １６ and R １８ are preferably the same group, and when each of them forms a ring, A １ ＋ and A ２ It is preferred that the rings have the same structure except for the following:

[0193] R in Formula 1-1 １５ and R１７ are preferably the same group. １５ and R １７ is -R ａ (i.e., a hydrocarbon group), more preferably an alkyl group, and even more preferably a substituted alkyl group.

[0194] In the compound represented by formula 1-1, from the viewpoint of improving water solubility, R １５ and R １７ is preferably a substituted alkyl group. １５ or R １７ Examples of the substituted alkyl group represented by the formula (a1) include groups represented by any one of the following formulas (a1) to (a4).

[0195]

[0196] In formulas (a1) to (a4), R Ｗ０ represents an alkylene group having 2 to 6 carbon atoms, W represents a single bond or an oxygen atom, n Ｗ１ represents an integer of 1 to 45, R Ｗ１ is an alkyl group having 1 to 12 carbon atoms or —C(═O)—R Ｗ５ represents R Ｗ５ represents an alkyl group having 1 to 12 carbon atoms, and R Ｗ２ ~R Ｗ４ each independently represents a single bond or an alkylene group having 1 to 12 carbon atoms, and M represents a hydrogen atom, a sodium atom, a potassium atom, or an onium group.

[0197] In formula (a1), R Ｗ０ Specific examples of the alkylene group represented by the formula (I) include an ethylene group, an n-propylene group, an isopropylene group, an n-butylene group, an isobutylene group, an n-pentylene group, an isopentylene group, an n-hexyl group, an isohexyl group, etc., and an ethylene group, an n-propylene group, an isopropylene group, or an n-butylene group is preferred, and an n-propylene group is particularly preferred. Ｗ１ is preferably 1 to 10, more preferably 1 to 5, and particularly preferably 1 to 3. Ｗ１Specific examples of the alkyl group represented by R include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, an n-pentyl group, an isopentyl group, a neopentyl group, an n-hexyl group, an n-octyl group, and an n-dodecyl group, of which a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, or a tert-butyl group is preferred, a methyl group or an ethyl group is more preferred, and a methyl group is particularly preferred. Ｗ５ The alkyl group represented by R Ｗ１ The preferred embodiment is the same as the alkyl group represented by R Ｗ１ The preferred embodiments are the same as those of the alkyl group represented by the following formula:

[0198] Specific examples of the group represented by formula (a1) are shown below, but the present disclosure is not limited to these. In the following structural formula, Me represents a methyl group, Et represents an ethyl group, and * represents a bonding site.

[0199]

[0200] In formulas (a2) to (a4), R Ｗ２ ~R Ｗ４ Specific examples of the alkylene group represented by the formula (a3) ​​include a methylene group, an ethylene group, an n-propylene group, an isopropylene group, an n-butylene group, an isobutylene group, an n-pentylene group, an isopentylene group, an n-hexyl group, an isohexyl group, an n-octylene group, an n-dodecylene group, etc., and an ethylene group, an n-propylene group, an isopropylene group, or an n-butylene group is preferred, and an ethylene group or an n-propylene group is particularly preferred. In formula (a3), two M's may be the same or different.

[0201] In formulas (a2) to (a4), examples of the onium group represented by M include an ammonium group, an iodonium group, a phosphonium group, and a sulfonium group. ２ M, PO in formula (a2) ３ M ２ , and SO in formula (a4) ３ Each of M may have an anionic structure in which M is dissociated. The counter cation of the anionic structure is A １＋ or R in Formula 1-1 １ -It may be a cation that can be contained in L.

[0202] Among the groups represented by formulae (a1) to (a4), groups represented by formula (a1), formula (a2) or formula (a4) are preferred.

[0203] n in Formula 1-1 １１ and n １２ are preferably the same, and are both preferably integers of 1 to 5, more preferably integers of 1 to 3, even more preferably 1 or 2, and particularly preferably 2.

[0204] A in Formula 1-1 １ and A ２ each independently represents an oxygen atom, a sulfur atom, or a nitrogen atom, and a nitrogen atom is preferable. １ and A ２ are preferably the same atom.

[0205] Za in Formula 1-1 represents a counter ion that neutralizes the charge. １１ ~R １８ and R １ If all of -L are charge-neutral groups, Za is a monovalent counter anion. １１ ~R １８ and R １ -L may have an anionic or cationic structure, for example, R １１ ~R １８ and R １When -L has two or more anionic structures, Za can also serve as a counter cation. Note that, when the cyanine dye represented by Formula 1-1 has a structure in which the entire compound, excluding Za, is charge-neutral, Za is not necessary. When Za is a counter anion, examples thereof include a sulfonate ion, a carboxylate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, a p-toluenesulfonate ion, a perchlorate ion, and the like, with a tetrafluoroborate ion being preferred. When Za is a counter cation, examples thereof include an alkali metal ion, an alkaline earth metal ion, an ammonium ion, a pyridinium ion, a sulfonium ion, and the like, with a sodium ion, a potassium ion, an ammonium ion, a pyridinium ion, or a sulfonium ion being preferred, with a sodium ion, a potassium ion, or an ammonium ion being more preferred.

[0206] From the viewpoint of improving the visibility of the exposed area, the decomposable infrared absorber is more preferably a compound represented by the following formula 1-2 (that is, a cyanine dye).

[0207]

[0208] In formula 1-2, R １ represents a group represented by any one of the above formulas 2-1 to 4-1, and R １９ ~R ２２ are each independently a hydrogen atom, a halogen atom, or —R ａ , -OR ｂ , -CN, -SR ｃ , or -NR ｄ R ｅ represents R ２３ and R ２４ are each independently a hydrogen atom or -R ａ represents R ａ ~R ｅ each independently represents a hydrocarbon group; R １９ and R ２０ , R ２１ and R ２２ , or R ２３ and R ２４ may be linked to form a monocycle or polycycle, and L is an oxygen atom, a sulfur atom, or —NR １０ represents -, and R１０ represents a hydrogen atom, an alkyl group, or an aryl group; R ｄ１ ~R ｄ４ , W １ and W ２ each independently represents an alkyl group which may have a substituent, and Za represents a counter ion which neutralizes the charge.

[0209] R in Formula 1-2 １ is R in Formula 1-1 １ The same applies to the preferred embodiments.

[0210] In Formula 1-2, R １９ ~R ２２ are each independently a hydrogen atom, a halogen atom, or —R ａ , -OR ｂ More specifically, R １９ and R ２１ is a hydrogen atom or -R ａ It is preferable that R ２０ and R ２２ is a hydrogen atom, -R ａ , -OR ｂ or —CN. １９ ~R ２２ -R represented by ａ is preferably an alkyl group or an alkenyl group. １９ ~R ２２ All of -R ａ If R １９ and R ２０ and R ２１ and R ２２ are preferably linked to form a monocyclic or polycyclic ring. １９ and R ２０ or R ２１ and R ２２ Examples of the ring formed by linking include a benzene ring and a naphthalene ring.

[0211] In Formula 1-2, R ２３ and R ２４ are preferably linked to form a monocyclic or polycyclic ring. ２３ and R ２４The ring formed by linking may be a monocycle or a polycycle. Specific examples of the ring formed include monocycles such as a cyclopentene ring, a cyclopentadiene ring, a cyclohexene ring, and a cyclohexadiene ring, and polycycles such as an indene ring.

[0212] In Formula 1-2, R ｄ１ ~R ｄ４ is preferably an unsubstituted alkyl group. ｄ１ ~R ｄ４ are preferably the same group. The unsubstituted alkyl group includes an unsubstituted alkyl group having 1 to 4 carbon atoms, and among these, a methyl group is preferred.

[0213] In Formula 1-2, W １ and W ２ are each independently preferably a substituted alkyl group from the viewpoint of increasing the water solubility of the compound represented by formula 1-2. １ and W ２ Examples of the substituted alkyl group represented by the formula (a1) include groups represented by any one of formulas (a1) to (a4) in formula 1-1, and the same applies to preferred embodiments. １ and W ２ are each independently an alkyl group having a substituent from the viewpoint of on-press developability, and the substituent is —OCH ２ CH ２ It is preferable that the group has at least one of -, a sulfo group, a salt of a sulfo group, a carboxy group, or a salt of a carboxy group.

[0214] Za represents a counter ion that neutralizes the charge in the molecule. １９ ~R ２２ , R ２３ ~R ２４ , R ｄ１ ~R ｄ４ , W １ , W ２ , and R １ If all of -L are charge-neutral groups, Za is a monovalent counter anion. １９ ~R ２２ , R ２３ ~R ２４ , R ｄ１ ~Rｄ４ , W １ , W ２ , and R １ -L may have an anionic or cationic structure, for example, R １９ ~R ２２ , R ２３ ~R ２４ , R ｄ１ ~R ｄ４ , W １ , W ２ , and R １ When -L has two or more anionic structures, Za can also serve as a counter cation. Note that, if the compound represented by formula 1-2 has a structure in which the entire compound is charge-neutral except for Za, Za is not necessary. Examples of when Za is a counter anion are the same as Za in formula 1-1, and preferred embodiments are also the same. Furthermore, examples of when Za is a counter cation are the same as Za in formula 1-1, and preferred embodiments are also the same.

[0215] From the viewpoints of decomposability and visibility, the cyanine dye as the decomposable infrared absorber is more preferably a compound represented by any one of the following formulas 1-3 to 1-7. In particular, from the viewpoints of decomposability and visibility, a compound represented by any one of formulas 1-3, 1-5, and 1-6 is preferred.

[0216]

[0217] In formulas 1-3 to 1-7, R １ represents a group represented by any one of the above formulas 2-1 to 4-1, and R １９ ~R ２２ are each independently a hydrogen atom, a halogen atom, or —R ａ , -OR ｂ , -CN, -SR ｃ , or -NR ｄ R ｅ represents R ２５ and R ２６ are each independently a hydrogen atom, a halogen atom, or -R ａ represents R ａ ~R ｅ each independently represents a hydrocarbon group; R １９ and R ２０ , R２１ and R ２２ , or R ２５ and R ２６ may be linked to form a monocycle or polycycle, and L is an oxygen atom, a sulfur atom, or —NR １０ represents -, and R １０ represents a hydrogen atom, an alkyl group, or an aryl group; R ｄ１ ~R ｄ４ , W １ and W ２ each independently represents an alkyl group which may have a substituent, and Za represents a counter ion which neutralizes the charge.

[0218] R in Formulas 1-3 to 1-7 １ , R １９ ~R ２２ , R ｄ１ ~R ｄ４ , W １ , W ２ , and L is R in Formula 1-2 １ , R １９ ~R ２２ , R ｄ１ ~R ｄ４ , W １ , W ２ and L, and preferred embodiments are also the same. ２５ and R ２６ are each independently preferably a hydrogen atom or an alkyl group, more preferably an alkyl group, and particularly preferably a methyl group.

[0219] Specific examples of the cyanine dye as the decomposable infrared absorber are listed below, but the present disclosure is not limited to these.

[0220]

[0221] In addition, from the viewpoint of color development properties, the infrared absorber preferably contains a compound represented by the following formula (X) as a decomposable infrared absorber.

[0222]

[0223] In formula (X), Ar １１ and Ar １２each independently represents an atomic group necessary to form a substituted or unsubstituted aromatic ring or a substituted or unsubstituted heteroaromatic ring; R １１ and R １２ are each independently a substituted or unsubstituted alkyl group, R １３ represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group; R １４ represents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group; Y each independently represents an oxygen atom, a sulfur atom, or >C(R １５ R １６ ) represents a dialkylmethylene group represented by R １５ and R １６ each independently represents a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms; A １ and A ２ each independently represents a substituted or unsubstituted alkyl group, or represents a group of atoms containing 2 or 3 carbon atoms necessary to combine with each other to form a substituted or unsubstituted 5- or 6-membered non-aromatic carbon ring, and Za represents a counter ion that neutralizes the charge.

[0224] The above Ar １１ and Ar １２ each independently represents an atomic group necessary to form a substituted or unsubstituted aromatic ring or a substituted or unsubstituted heteroaromatic ring, and examples of the substituent of the aromatic ring or heteroaromatic ring include an alkyl group, an alkoxy group, a halogen atom, a cyano group, a —COOR group, and —SO ３ R group, or —SO ２ R groups (R represents a substituted or unsubstituted alkyl group), and alkyl groups or halogen atoms are preferred. １１ and Ar １２ is preferably an atomic group necessary for forming a substituted or unsubstituted aromatic ring, and more preferably an atomic group necessary for forming a substituted or unsubstituted benzene ring or naphthalene ring.

[0225] The above Ys each independently represent >C(R１５ R １６ ) is preferably a dialkylmethylene group represented by >C(R １５ R １６ ) and R １５ and R １６ are preferably the same dialkylmethylene group. １５ and R １６ are each independently a substituted or unsubstituted alkyl group having 1 or 2 carbon atoms. １５ R １６ ) and R １５ and R １６ is preferably a dialkylmethylene group in which R is a methyl group.

[0226] The above R １１ and R １２ is preferably a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms. １１ and R １２ may contain an ether bond or an ester bond in the carbon chain of the substituted or unsubstituted alkyl group having 1 to 12 carbon atoms.

[0227] The above R １３ is preferably a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, and more preferably a haloalkyl group in which one or more hydrogen atoms of the alkyl group having 1 to 12 carbon atoms are substituted with halogen atoms. In this case, preferred examples of the halogen atom include a chlorine atom and a bromine atom. Among these, the above R １１ and R １２ are each independently preferably a perfluoroalkyl group.

[0228] The above R １４ is preferably a hydrogen atom or an unsubstituted alkyl group having 1 or 8 carbon atoms.

[0229] Above A １ and A ２is preferably each independently a substituted or unsubstituted alkyl group, or an atomic group containing two or three carbon atoms necessary to bond to each other to form a cyclopentene ring or a cyclohexene ring.

[0230] When Za is a counter anion, it is preferably an anion containing a halogen atom or an anion containing a boron atom. ４ － , P.F. ６ － , B.F. ４ － , SbF ６ － , C.H. ３ SO ３ － , C.F. ３ SO ３ － , C ６ H ５ SO ３ － , C.H. ３ C ６ H ５ SO ３ － , H.O.C. ６ H ５ SO ３ － , ClC ６ H ５ SO ３ － , C.H. ３ C ６ H ５ SO ３ － , tetraarylborate anions (for example, tetraphenylborate anions), and the like.

[0231] When Za is a counter cation, examples thereof include alkali metal ions, alkaline earth metal ions, tertiary ammonium ions, quaternary ammonium ions, and onium ions (iodonium ions, sulfonium ions, phosphonium ions, etc.).

[0232] Specific examples of the compound represented by formula (X) are listed below, but the present disclosure is not limited to these. Ph represents a phenyl group.

[0233]

[0234] The decomposable infrared absorber preferably contains a compound represented by the following formula (P1).

[0235]

[0236] In formula (P1), R Ｐ１ represents a group represented by the following formula (P2) or formula (P3), and R Ｐ２ and R Ｐ３ each independently represents a hydrogen atom or an alkyl group; R Ｐ２ and R Ｐ３ may be linked to each other to form a ring, and Ar Ｐ１ and Ar Ｐ２ each independently represents a benzene ring or a naphthalene ring; Y Ｐ１ and Y Ｐ２ are each independently an oxygen atom, a sulfur atom, or —NR Ｐ０ - or a dialkylmethylene group, R Ｐ４ and R Ｐ５ each independently represents an alkyl group; R Ｐ６ ~RP ９ each independently represents a hydrogen atom or an alkyl group; R Ｐ０ represents a hydrogen atom, an alkyl group, or an aryl group, and Za represents a counter ion that neutralizes the charge.

[0237]

[0238] In formula (P2) and formula (P3), R Ｐ１０ represents a monovalent organic group having an aryl group, and R Ｐ１１ ~R Ｐ１４ and R Ｐ１７ ~R Ｐ２０ each independently represents a hydrogen atom, an alkyl group, an aryl group, a hydroxy group, an alkoxy group, or a halogen atom; R Ｐ１５ and R Ｐ１６ each independently represents a hydrogen atom, an alkyl group, or an aryl group; R Ｐ１１ ~R Ｐ２０ At least two of these may be bonded to form a ring structure, and * represents a single bond bonding to the oxygen atom in formula (P1).

[0239] The compound represented by formula (P1) has the property of decomposing by heat or infrared energy to produce a highly visible colored body. In this specification, "colored" means that the compound is more strongly colored after heating or infrared exposure than before heating or infrared exposure, or that the absorption becomes shorter in wavelength and the compound has absorption in the visible light region. That is, the compound represented by formula (P1) is a compound that decomposes by heat or infrared exposure, and the absorption in the visible light region increases, or the absorption becomes shorter in wavelength and the compound has absorption in the visible light region, compared to before heating or infrared exposure. The compound represented by formula (P1) is preferably a compound that decomposes by heat or infrared exposure to produce a compound having a maximum absorption wavelength in the range of 500 nm to 600 nm.

[0240] R Ｐ１ is preferably a group represented by the above formula (P2) from the viewpoints of visibility, printing durability, synthesis suitability, and raw material supplyability.

[0241] R Ｐ１０ From the viewpoints of visibility, printing durability, on-press developability, and on-press developability after aging, the aryl group in R is preferably an aryl group having 6 to 30 carbon atoms (also referred to as "number of carbon atoms"), more preferably an aryl group having 6 to 20 carbon atoms, and even more preferably an aryl group having 6 to 12 carbon atoms. Ｐ１０ From the viewpoints of visibility, printing durability, on-press developability, and on-press developability after aging, the aryl group in R is preferably an aryl group having one or more substituents on the aromatic ring, more preferably a phenyl group having one or more substituents on the aromatic ring, still more preferably a phenyl group having one or more alkyl groups on the aromatic ring, and particularly preferably an alkylphenyl group. Ｐ１０ From the viewpoints of visibility, printing durability, on-press developability, and on-press developability after aging, R is preferably a group having one or more substituents on the aromatic ring of an arylalkyl group, more preferably a group having one or more substituents on the aromatic ring of a benzyl group, still more preferably a benzyl group having one or more substituents (substituted benzyl group), and particularly preferably a benzyl group having an alkyl group on the benzene ring. Ｐ１０is preferably a group represented by formula (P4) from the viewpoints of visibility, printing durability, on-press developability, and on-press developability after aging.

[0242]

[0243] In formula (P4), X Ｐ２ represents a single bond or an alkylene group, Ar Ｐ３ represents an aryl group.

[0244] X Ｐ２ From the viewpoints of visibility, printing durability, and synthesis suitability, Ar is preferably an alkylene group, more preferably an alkylene group having 1 to 6 carbon atoms, even more preferably an alkylene group having 1 to 3 carbon atoms, particularly preferably an alkylene group having 1 or 2 carbon atoms, and most preferably a methylene group. Ｐ３ From the viewpoints of visibility, printing durability, and synthesis suitability, an aryl group having 6 to 30 carbon atoms is preferred, an aryl group having 6 to 20 carbon atoms is more preferred, and an aryl group having 6 to 12 carbon atoms is even more preferred. The aryl group may have a substituent, and preferably has one or more substituents. Examples of the substituent include an alkyl group, an alkoxy group, an aryloxy group, an amino group, an alkylthio group, an arylthio group, a halogen atom, a carboxy group, a carboxylate group, a sulfo group, a sulfonate group, an alkyloxycarbonyl group, an aryloxycarbonyl group, and combinations thereof. Specific examples include a phenyl group, a naphthyl group, a p-tolyl group, a p-ethylphenyl group, a p-t-butylphenyl group, a p-chlorophenyl group, a p-fluorophenyl group, a p-methoxyphenyl group, a p-dimethylaminophenyl group, a p-methylthiophenyl group, a p-phenylthiophenyl group, a p-phenylphenyl group, an o-tolyl group, an o-ethylphenyl group, an o-tBuphenyl group, an o-chlorophenyl group, an o-fluorophenyl group, an o-methoxyphenyl group, an o-dimethylaminophenyl group, an o-methylthiophenyl group, and an o-phenylthiophenyl group.

[0245] Also, Ar Ｐ３is preferably an aryl group having one or more substituents on the aromatic ring, more preferably a phenyl group having one or more substituents on the aromatic ring (substituted phenyl group), still more preferably an alkylphenyl group, particularly preferably a phenyl group having a branched alkyl group, and most preferably a t-butylphenyl group, from the viewpoints of visibility, printing durability, on-press developability, and on-press developability after aging. Furthermore, the alkylphenyl group is preferably a p-alkylphenyl group from the viewpoints of visibility, printing durability, on-press developability, and on-press developability after aging.

[0246] R Ｐ１１ ~R Ｐ１４ and R Ｐ１７ ~R Ｐ２０ represents a hydrogen atom, an alkyl group, an aryl group, a hydroxy group, an alkoxy group, or a halogen atom, and may be the same group or different groups. Ｐ１１ ~R Ｐ１４ and R Ｐ１７ ~R Ｐ２０ may be linked to form a ring. Ｐ１１ ~R Ｐ１４ and R Ｐ１７ ~R Ｐ２０ The alkyl group in the formula (I) may be linear, branched, or have a ring structure. Specific examples include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, hexadecyl, octadecyl, eicosyl, isopropyl, isobutyl, s-butyl, t-butyl, isopentyl, neopentyl, 1-methylbutyl, isohexyl, 2-ethylhexyl, 2-methylhexyl, cyclohexyl, cyclopentyl, and 2-norbornyl. Among the alkyl groups, methyl, ethyl, propyl, and butyl groups are preferred.

[0247] R Ｐ１１ ~R Ｐ１４ and R Ｐ１７ ~R Ｐ２０The alkyl group in may have a substituent. Examples of the substituent include an aryl group, an alkoxy group, an aryloxy group, an amino group, an alkylthio group, an arylthio group, a halogen atom, a carboxy group, a carboxylate group, a sulfo group, a sulfonate group, an alkyloxycarbonyl group, an aryloxycarbonyl group, and combinations thereof.

[0248] R Ｐ１１ ~R Ｐ１４ and R Ｐ１７ ~R Ｐ２０ The aryl group in the formula (I) is preferably an aryl group having 6 to 30 carbon atoms, more preferably an aryl group having 6 to 20 carbon atoms, and even more preferably an aryl group having 6 to 12 carbon atoms. The aryl group may have a substituent. Examples of the substituent include an alkyl group, an alkoxy group, an aryloxy group, an amino group, an alkylthio group, an arylthio group, a halogen atom, a carboxy group, a carboxylate group, a sulfo group, a sulfonate group, an alkyloxycarbonyl group, an aryloxycarbonyl group, and combinations thereof. Specific examples include a phenyl group, a naphthyl group, a p-tolyl group, a p-chlorophenyl group, a p-fluorophenyl group, a p-methoxyphenyl group, a p-dimethylaminophenyl group, a p-methylthiophenyl group, and a p-phenylthiophenyl group. Among the aryl groups, a phenyl group, a p-methoxyphenyl group, a p-dimethylaminophenyl group, or a naphthyl group is preferred.

[0249] R Ｐ１１ ~R Ｐ１４ and R Ｐ１７ ~R Ｐ２０ are each independently preferably a hydrogen atom, an alkyl group, an alkoxy group, or a halogen atom, and particularly preferably a hydrogen atom, from the viewpoints of visibility and printing durability.

[0250] R Ｐ１５ and R Ｐ１６ represents a hydrogen atom, an alkyl group, or an aryl group, and may be the same group or different groups. Ｐ１５ is preferably a hydrogen atom from the viewpoints of visibility, printing durability, and synthesis suitability. Ｐ１６From the viewpoints of visibility and printing durability, R is preferably an alkyl group or an aryl group, more preferably an alkyl group, even more preferably a branched alkyl group, and particularly preferably a t-butyl group. Ｐ１６ In terms of visibility and printing durability, preferred branched alkyl groups in R include an isopropyl group, a t-butyl group, an isobutyl group, a cyclopentyl group, and a cyclohexyl group. Ｐ１６ In terms of visibility and printing durability, the aryl group in the formula (I) is preferably a phenyl group.

[0251] R Ｐ１５ and R Ｐ１６ The alkyl group in R is preferably an alkyl group having 1 to 20 carbon atoms, more preferably an alkyl group having 1 to 10 carbon atoms, and even more preferably an alkyl group having 1 to 6 carbon atoms. Ｐ１５ and R Ｐ１６ The alkyl group in may be linear, branched, or have a ring structure. Specific examples include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, hexadecyl, octadecyl, eicosyl, isopropyl, isobutyl, s-butyl, t-butyl, isopentyl, neopentyl, 1-methylbutyl, isohexyl, 2-ethylhexyl, 2-methylhexyl, cyclohexyl, cyclopentyl, and 2-norbornyl. Among the alkyl groups, methyl, ethyl, propyl, isopropyl, butyl, t-butyl, isobutyl, cyclopentyl, and cyclohexyl are preferred. Ｐ１５ and R Ｐ１６ The alkyl group in may have a substituent. Examples of the substituent include an aryl group, an alkoxy group, an aryloxy group, an amino group, an alkylthio group, an arylthio group, a halogen atom, a carboxy group, a carboxylate group, a sulfo group, a sulfonate group, an alkyloxycarbonyl group, an aryloxycarbonyl group, and a group formed by combining these groups. Ｐ１５ and R Ｐ１６A preferred embodiment of the aryl group in R Ｐ１１ ~R Ｐ１４ and R Ｐ１７ ~R Ｐ２０ The preferred embodiments are the same as those of the aryl group in the above.

[0252] R Ｐ２ , R Ｐ３ , R Ｐ６ , R Ｐ７ , R Ｐ８ , R Ｐ９ and R Ｐ０ A preferred embodiment of the alkyl group in R Ｐ１１ ~R Ｐ１４ and R Ｐ１７ ~R Ｐ２０ The preferred embodiments of the alkyl group in R Ｐ０ A preferred embodiment of the aryl group in R Ｐ１１ ~R Ｐ１４ and R Ｐ１７ ~R Ｐ２０ The preferred embodiments are the same as those of the aryl group in the above.

[0253] R Ｐ２ and R Ｐ３ are preferably linked to form a ring. Ｐ２ and R Ｐ３ When they are linked to form a ring, a 5-membered or 6-membered ring is preferred, and a 5-membered ring is particularly preferred.

[0254] Y Ｐ１ and Y Ｐ２ are each independently an oxygen atom, a sulfur atom, or —NR Ｐ０ represents - or a dialkylmethylene group, -NR Ｐ０ - or a dialkylmethylene group is preferred, and a dialkylmethylene group is more preferred. Ｐ０ represents a hydrogen atom, an alkyl group or an aryl group, and is preferably an alkyl group.

[0255] R Ｐ４ or R Ｐ５ The alkyl group in R is preferably an alkyl group having 1 to 30 carbon atoms, more preferably an alkyl group having 1 to 15 carbon atoms, and even more preferably an alkyl group having 1 to 10 carbon atoms. Ｐ４ or R Ｐ５The alkyl group in may be linear, branched, or have a ring structure. Specific examples include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, a hexadecyl group, an octadecyl group, an eicosyl group, an isopropyl group, an isobutyl group, a s-butyl group, a t-butyl group, an isopentyl group, a neopentyl group, a 1-methylbutyl group, an isohexyl group, a 2-ethylhexyl group, a 2-methylhexyl group, a cyclohexyl group, a cyclopentyl group, and a 2-norbornyl group.

[0256] R Ｐ４ or R Ｐ５ The alkyl group in may have a substituent. Examples of the substituent include an aryl group, an alkoxy group, an aryloxy group, an amino group, an alkylthio group, an arylthio group, a halogen atom, a carboxy group, a carboxylate group, a sulfo group, a sulfonate group, an alkyloxycarbonyl group, an aryloxycarbonyl group, and combinations thereof.

[0257] R Ｐ４ or R Ｐ５ Among the alkyl groups in R, a methyl group, an ethyl group, a propyl group, or a butyl group is preferred. As a substituent on the alkyl group, a methoxy group, a phenoxy group, a phenyl group, or a naphthyl group is preferred. Ｐ４ or R Ｐ５ From the viewpoint of solubility and developability, the alkyl group in R is particularly preferably an ethyl group or a propyl group having a substituent (for example, a substituent in Dye-12 described later). Ｐ４ and R Ｐ５ are preferably the same group.

[0258] R Ｐ６ ~R Ｐ９ each independently represents a hydrogen atom or an alkyl group, and is preferably a hydrogen atom.

[0259] Ar Ｐ１ and Ar Ｐ２each independently represents a group forming a benzene ring or a naphthalene ring. The benzene ring and the naphthalene ring may have a substituent. Examples of the substituent include an alkyl group, an alkoxy group, an aryloxy group, an amino group, an alkylthio group, an arylthio group, a halogen atom, a carboxy group, a carboxylate group, a sulfo group, a sulfonate group, an alkyloxycarbonyl group, an aryloxycarbonyl group, an acyloxy group, a phosphonic acid group, and a group combining these. The substituent is preferably an alkyl group or an alkoxy group. Furthermore, from the viewpoint of lengthening the maximum absorption wavelength of the compound represented by formula (P1) and improving the color developability and the printing durability of the lithographic printing plate, Ar Ｐ１ and Ar Ｐ２ are each independently preferably a group that forms a naphthalene ring or a benzene ring having an alkyl group or an alkoxy group as a substituent, more preferably a group that forms a naphthalene ring or a benzene ring having an alkoxy group as a substituent, and particularly preferably a group that forms a benzene ring having a methoxy group as a substituent.

[0260] In formula (P1), Ar Ｐ１ or Ar Ｐ２ is preferably a group that forms a group represented by the following formula:

[0261]

[0262] In the above formula, R Ｐ２１ each independently represents an alkyl group, an alkoxy group, an aryloxy group, an amino group, an alkoxythio group, or a halogen atom having 1 to 12 carbon atoms; nP3 represents an integer of 1 to 4; and Ｐ２１ may be bonded to each other to form a ring, and * represents the bonding site.

[0263] Za represents a counter ion for neutralizing the charge. Depending on the valence to be neutralized, the counter ion may be one type of counter ion or two or more types of counter ions, or two or more counter ions of the same or different types may be present. However, when the compound represented by formula (P1) has a corresponding ionic substituent in its structure and charge neutralization is not required, Za is not required. When representing an anionic species, examples include sulfonate ions, carboxylate ions, tetrafluoroborate ions, hexafluorophosphate ions, p-toluenesulfonate ions, perchlorate ions, etc., with tetrafluoroborate ions, hexafluorophosphate ions, and p-toluenesulfonate ions being preferred. When representing a cationic species, examples include alkali metal ions, alkaline earth metal ions, ammonium ions, pyridinium ions, and sulfonium ions, with sodium ions, potassium ions, ammonium ions, pyridinium ions, and sulfonium ions being preferred, with sodium ions, potassium ions, and ammonium ions being more preferred.

[0264] R Ｐ２ ~R Ｐ９ , R Ｐ０ , Ar Ｐ１ , Ar Ｐ２ , Y Ｐ１ and Y Ｐ２ may have an anionic structure or a cationic structure, and R Ｐ２ ~R Ｐ９ , R Ｐ０ , Ar Ｐ１ , Ar Ｐ２ , Y Ｐ１ and Y Ｐ２ If all of the groups are charge-neutral, Za is a monovalent counter anion or a divalent counter anion, for example, R Ｐ２ ~R Ｐ９ , R Ｐ０ , Ar Ｐ１ , Ar Ｐ２ , Y Ｐ１ and Y Ｐ２ When the compound has two or more anionic structures, Za can also be a counter cation.

[0265] From the viewpoints of visibility, printing durability, on-press developability, and on-press developability after aging, the compound represented by formula (P1) is preferably a compound represented by formula (P5) or formula (P6) below, more preferably a compound represented by formula (P7) or formula (P8) below, and particularly preferably a compound represented by formula (P9) below.

[0266]

[0267] In formula (P5) and formula (P6), R Ｐ４ and R Ｐ５ each independently represents an alkyl group; R Ｐ１０ represents a monovalent organic group having an aryl group, and R Ｐ１１ ~R Ｐ１４ and R Ｐ１７ ~R Ｐ２０ each independently represents a hydrogen atom, an alkyl group, an aryl group, a hydroxy group, an alkoxy group, or a halogen atom; R Ｐ１５ and R Ｐ１６ each independently represents a hydrogen atom, an alkyl group, or an aryl group; R Ｐ１１ ~R Ｐ２０ At least two of R may be bonded to form a ring structure; Ｐ２１ each independently represents an alkyl group having 1 to 12 carbon atoms, an alkoxy group, an aryloxy group, an amino group, an alkoxythio group, or a halogen atom, and Za represents a counter ion that neutralizes the charge.

[0268]

[0269] In formula (P7) and formula (P8), X Ｐ２ represents a single bond or an alkylene group, Ar Ｐ３ represents an aryl group, R ４ and R ５ each independently represents an alkyl group; R Ｐ１５ and R Ｐ１６ each independently represents a hydrogen atom, an alkyl group, or an aryl group; R Ｐ１５ and R Ｐ１６ may be bonded to form a ring structure, and R Ｐ２１each independently represents an alkyl group having 1 to 12 carbon atoms, an alkoxy group, an aryloxy group, an amino group, an alkoxythio group, or a halogen atom, and Za represents a counter ion that neutralizes the charge.

[0270]

[0271] In formula (P9), Ar Ｐ４ represents an aryl group, R Ｐ４ and R Ｐ５ each independently represents an alkyl group; R Ｐ２１ each independently represents an alkyl group having 1 to 12 carbon atoms, an alkoxy group, an aryloxy group, an amino group, an alkoxythio group, or a halogen atom; R Ｐ２２ represents a hydrogen atom, an alkyl group, or an aryl group; R Ｐ２３ each independently represents a hydrogen atom or an alkyl group, and Za represents a counter ion that neutralizes the charge.

[0272] R in formulas (P5) to (P9) Ｐ４ , R Ｐ５ , R Ｐ１１ ~R Ｐ２０ Preferred embodiments of and Za are R in formula (P1) to formula (P3), respectively. Ｐ４ , R Ｐ５ , R Ｐ１１ ~R Ｐ２０ The preferred embodiments of R in formula (P5) to formula (P9) are the same as those of Za. Ｐ２１ Each of the preferred embodiments of R Ｐ２１ The preferred embodiments of X in formula (P7) and formula (P8) are the same as those of Ｐ２ and Ar Ｐ３ In each of the preferred embodiments, X in formula (P4) Ｐ２ and Ar Ｐ３ This is the same as the preferred embodiment of the above.

[0273] Ar in formula (P9) Ｐ４is preferably an aryl group having 6 to 30 carbon atoms, more preferably an aryl group having 6 to 20 carbon atoms, and even more preferably an aryl group having 6 to 12 carbon atoms. The aryl group may have a substituent. Examples of the substituent include an alkyl group, an alkoxy group, an aryloxy group, and a group formed by combining these. Among these, an alkyl group is preferred as the substituent. Ar in formula (P9) Ｐ４ Specific examples of Ar include a phenyl group, a naphthyl group, a p-tolyl group, a p-ethylphenyl group, a p-t-butylphenyl group, a p-fluorophenyl group, and a p-methoxyphenyl group. Ｐ４ As the group, from the viewpoints of visibility, printing durability, on-press developability, and on-press developability after aging, a phenyl group, a p-methoxyphenyl group, a p-tBuphenyl group, or a naphthyl group is preferable, a phenyl group, a p-methoxyphenyl group, or a p-t-butylphenyl group is more preferable, and a p-t-butylphenyl group is particularly preferable.

[0274] R in formula (P9) Ｐ２２ is preferably an alkyl group, more preferably an alkyl group having 1 to 8 carbon atoms, which may be separated by an oxygen atom or the like. From the viewpoints of visibility, printing durability, and synthesis suitability, the number of carbon atoms in the alkyl group is more preferably 1 to 6, even more preferably 3 to 5, and particularly preferably 3 or 4. From the viewpoints of visibility, printing durability, and synthesis suitability, R in formula (P9) Ｐ２３ is preferably a hydrogen atom from the viewpoint of production suitability.

[0275] Preferred specific examples of the compound represented by formula (P1) are shown below, but are not limited to these. In the following structural formula, Me represents a methyl group, and TsO － represents the tosylate anion.

[0276]

[0277]

[0278]

[0279]

[0280]

[0281]

[0282]

[0283]

[0284] In addition, as the infrared absorber that decomposes upon exposure to infrared light, those described in JP-A No. 2008-544322 or WO 2016 / 027886 can be suitably used. In addition, as the cyanine dye that is a decomposable infrared absorber, the infrared absorbing compound described in WO 2019 / 219560 can be suitably used.

[0285] The infrared absorbent may be used alone or in combination of two or more. In one embodiment, the image recording layer preferably contains two or more infrared absorbents. By using two or more infrared absorbents in combination, the ability to suppress development defects over time and printing durability are further improved. Furthermore, a pigment and a dye may be used in combination as the infrared absorbent. The total content of the infrared absorbents in the image recording layer is preferably 0.1% by mass to 10.0% by mass, more preferably 0.5% by mass to 5.0% by mass, relative to the total mass of the image recording layer.

[0286] [Relationship Between Specific Borate Compound (Electron-Donating Polymerization Initiator), Electron-Accepting Polymerization Initiator, and Infrared Absorber] The image recording layer in the present disclosure preferably contains a specific borate compound, an electron-accepting polymerization initiator, and further contains an infrared absorber. When the image recording layer contains a specific borate compound, an electron-accepting polymerization initiator, and an infrared absorber, it is preferable that the HOMO of the specific borate compound is −6.0 eV or more, and the LUMO of the electron-accepting polymerization initiator is −3.0 eV or less. More preferred aspects of the HOMO of the specific borate compound and the LUMO of the electron-accepting polymerization initiator are as described above. In the image recording layer in the present disclosure, it is presumed that the specific borate compound, at least one infrared absorber, and the electron-accepting polymerization initiator exchange energy, for example, as shown in the following chemical formula: Therefore, if the HOMO of the specific borate compound is −6.0 eV or more and the LUMO of the electron-accepting polymerization initiator is −3.0 eV or less, it is considered that the radical generation efficiency is improved, and therefore the chemical resistance and printing durability are more likely to be excellent.

[0287]

[0288] From the viewpoint of printing durability and chemical resistance, the HOMO value of at least one of the infrared absorbers and the HOMO value of the specific borate compound is preferably 1.0 eV or less, more preferably 0.70 eV or less, and particularly preferably 0.60 eV or less. From the same viewpoint, the HOMO value of at least one of the infrared absorbers and the HOMO value of the specific borate compound is preferably -0.200 eV or more, more preferably -0.100 eV or more. Note that a negative value means that the HOMO of the specific borate compound is higher than the HOMO of at least one of the infrared absorbers. From the viewpoint of printing durability and chemical resistance, the LUMO value of the electron-accepting polymerization initiator and the LUMO value of at least one of the infrared absorbers is preferably 1.00 eV or less, more preferably 0.700 eV or less. From the same viewpoint, the LUMO value of the electron-accepting polymerization initiator minus the LUMO value of at least one of the infrared absorbers is preferably −0.200 eV or higher, and more preferably −0.100 eV or higher. From the same viewpoint, the LUMO value of the electron-accepting polymerization initiator minus the LUMO value of at least one of the infrared absorbers is preferably 1.00 eV to −0.200 eV, and more preferably 0.700 eV to −0.100 eV. A negative value means that the LUMO of at least one of the infrared absorbers is higher than the LUMO of the electron-accepting polymerization initiator.

[0289] <Color Former> The image recording layer preferably contains a color former, and more preferably contains an acid color former. As used herein, the term "color former" refers to a compound that develops or fades color in response to a stimulus such as light or acid, thereby changing the color of the image recording layer. The term "acid color former" refers to a compound that develops or fades color in response to a stimulus such as light or acid, thereby changing the color of the image recording layer. The term "acid color former" refers to a compound that develops or fades color in response to a stimulus such as light or acid, thereby changing the color of the image recording layer. The acid color former is preferably a colorless compound that has a partial skeleton such as a lactone, lactam, sultone, spiropyran, ester, or amide, and that rapidly undergoes ring-opening or cleavage upon contact with the electron-accepting compound.

[0290] Examples of such acid color formers include 3,3-bis(4-dimethylaminophenyl)-6-dimethylaminophthalide (also known as "crystal violet lactone"), 3,3-bis(4-dimethylaminophenyl)phthalide, 3-(4-dimethylaminophenyl)-3-(4-diethylamino-2-methylphenyl)-6-dimethylaminophthalide, 3-(4-dimethylaminophenyl)-3-(1,2-dimethylindol-3-yl)phthalide, 3-(4-dimethylaminophenyl)-3-(2-methylphenyl) ... 3-(4-dimethylaminophenyl)-3-(1-methylpyrrol-3-yl)phthalide, 3,3-bis(1,2-dimethylindol-3-yl)-5-dimethylaminophthalide, 3,3-bis(1,2-dimethylindol-3-yl)-6-dimethylaminophthalide, 3,3-bis(9-ethylcarbazol-3-yl)-6-dimethylaminophthalide, 3,3-bis(2-phenylindol-3-yl)-6-dimethylaminophthalide, 3-(4-dimethylaminophenyl)-3-(1-methylpyrrol-3-yl)-6-dimethylaminophthalide,

[0291] 3,3-bis[1,1-bis(4-dimethylaminophenyl)ethylene-2-yl]-4,5,6,7-tetrachlorophthalide, 3,3-bis[1,1-bis(4-pyrrolidinophenyl)ethylene-2-yl]-4,5,6,7-tetrabromophthalide, 3,3-bis[1-(4-dimethylaminophenyl)-1-(4-methoxyphenyl)ethylene-2-yl]-4,5,6,7-tetrachlorophthalide, 3,3-bis[1-(4-pyrrolidinophenyl)-1-(4-methoxyphenyl)ethylene-2-yl]-4,5,6,7-tetrachlorophthalide, 3-[1,1-di(1-ethyl-2-methylin phthalides such as 3-[1,1-di(1-ethyl-2-methylindol-3-yl)ethylene-2-yl]-3-(4-diethylaminophenyl)phthalide, 3-[1,1-di(1-ethyl-2-methylindol-3-yl)ethylene-2-yl]-3-(4-N-ethyl-N-phenylaminophenyl)phthalide, 3-(2-ethoxy-4-diethylaminophenyl)-3-(1-n-octyl-2-methylindol-3-yl)phthalide, 3,3-bis(1-n-octyl-2-methylindol-3-yl)phthalide, and 3-(2-methyl-4-diethylaminophenyl)-3-(1-n-octyl-2-methylindol-3-yl)phthalide;

[0292] 4,4-bis-dimethylaminobenzhydrin benzyl ether, N-halophenyl-leucoauramine, N-2,4,5-trichlorophenylleucoauramine, rhodamine-B-anilinolactam, rhodamine-(4-nitroanilino)lactam, rhodamine-B-(4-chloroanilino)lactam, 3,7-bis(diethylamino)-10-benzoylphenoxazine, benzoylleuco methylene blue, 4-nitrobenzoyl methylene blue,

[0293] 3,6-dimethoxyfluoran, 3-dimethylamino-7-methoxyfluoran, 3-diethylamino-6-methoxyfluoran, 3-diethylamino-7-methoxyfluoran, 3-diethylamino-7-chlorofluoran, 3-diethylamino-6-methyl-7-chlorofluoran, 3-diethylamino-6,7-dimethylfluoran, 3-N-cyclohexyl-N-n-butylamino-7-methylfluoran, 3-diethylamino-7-dibenzylaminofluoran, 3-diethylamino-7-octylaminofluoran, 3-diethylamino-7-di-n-hexylaminofluoran, 3-diethylamino-7-anilinofluoran, 3 -diethylamino-7-(2'-fluorophenylamino)fluoran, 3-diethylamino-7-(2'-chlorophenylamino)fluoran, 3-diethylamino-7-(3'-chlorophenylamino)fluoran, 3-diethylamino-7-(2',3'-dichlorophenylamino)fluoran, 3-diethylamino-7-(3'-trifluoromethylphenylamino)fluoran, 3-di-n-butylamino-7-(2'-fluorophenylamino)fluoran, 3-di-n-butylamino-7-(2'-chlorophenylamino)fluoran, 3-N-isopentyl-N-ethylamino-7-(2'-chlorophenylamino)fluoran,

[0294] 3-N-n-hexyl-N-ethylamino-7-(2'-chlorophenylamino)fluoran, 3-diethylamino-6-chloro-7-anilinofluoran, 3-di-n-butylamino-6-chloro-7-anilinofluoran, 3-diethylamino-6-methoxy-7-anilinofluoran, 3-di-n-butylamino-6-ethoxy-7-anilinofluoran, 3-pyrrolidino-6-methyl-7-anilinofluoran, 3-piperidino-6-methyl-7-anilinofluoran, 3-morpholino-6- Methyl-7-anilinofluoran, 3-dimethylamino-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-anilinofluoran, 3-di-n-butylamino-6-methyl-7-anilinofluoran, 3-di-n-pentylamino-6-methyl-7-anilinofluoran, 3-N-ethyl-N-methylamino-6-methyl-7-anilinofluoran, 3-N-n-propyl-N-methylamino-6-methyl-7-anilinofluoran, 3-N-n-propyl-N-ethylamino amino-6-methyl-7-anilinofluoran, 3-N-n-butyl-N-methylamino-6-methyl-7-anilinofluoran, 3-N-n-butyl-N-ethylamino-6-methyl-7-anilinofluoran, 3-N-isobutyl-N-methylamino-6-methyl-7-anilinofluoran, 3-N-isobutyl-N-ethylamino-6-methyl-7-anilinofluoran, 3-N-isopentyl-N-ethylamino-6-methyl-7-anilinofluoran, 3-N-hexyl-N-methylamino no-6-methyl-7-anilinofluoran, 3-N-cyclohexyl-N-ethylamino-6-methyl-7-anilinofluoran, 3-N-cyclohexyl-N-n-propylamino-6-methyl-7-anilinofluoran, 3-N-cyclohexyl-N-n-butylamino-6-methyl-7-anilinofluoran, 3-N-cyclohexyl-N-n-hexylamino-6-methyl-7-anilinofluoran, 3-N-cyclohexyl-N-n-octylamino-6-methyl-7-anilinofluoran,

[0295] 3-N-(2'-methoxyethyl)-N-methylamino-6-methyl-7-anilinofluoran, 3-N-(2'-methoxyethyl)-N-ethylamino-6-methyl-7-anilinofluoran, 3-N-(2'-methoxyethyl)-N-isobutylamino-6-methyl-7-anilinofluoran, 3-N-(2'-ethoxyethyl)-N-methylamino-6-methyl-7-anilinofluoran, 3-N-(2'-ethoxyethyl)-N-ethylamino-6-methyl-7 -anilinofluoran, 3-N-(3'-methoxypropyl)-N-methylamino-6-methyl-7-anilinofluoran, 3-N-(3'-methoxypropyl)-N-ethylamino-6-methyl-7-anilinofluoran, 3-N-(3'-ethoxypropyl)-N-methylamino-6-methyl-7-anilinofluoran, 3-N-(3'-ethoxypropyl)-N-ethylamino-6-methyl-7-anilinofluoran, 3-N-(2'-tetrahydrofurfuryl)- N-ethylamino-6-methyl-7-anilinofluoran, 3-N-(4'-methylphenyl)-N-ethylamino-6-methyl-7-anilinofluoran, 3-diethylamino-6-ethyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-(3'-methylphenylamino)fluoran, 3-diethylamino-6-methyl-7-(2',6'-dimethylphenylamino)fluoran, 3-di-n-butylamino-6-methyl-7-(2',6'-dimethylphenylamino)fluoran fluorans such as 3-[4'-(4-phenylaminophenyl)aminophenyl]amino-6-methyl-7-chlorofluoran, 3-di-n-butylamino-7-(2',6'-dimethylphenylamino)fluoran, 2,2-bis[4'-(3-N-cyclohexyl-N-methylamino-6-methylfluoran)-7-ylaminophenyl]propane, 3-[4'-(4-phenylaminophenyl)aminophenyl]amino-6-methyl-7-chlorofluoran, and 3-[4'-(dimethylaminophenyl)]amino-5,7-dimethylfluoran;

[0296] 3-(2-methyl-4-diethylaminophenyl)-3-(1-ethyl-2-methylindol-3-yl)-4-azaphthalide, 3-(2-n-propoxycarbonylamino-4-di-n-propylaminophenyl)-3-(1-ethyl-2-methylindol-3-yl)-4-azaphthalide, 3-(2-methylamino-4-di-n-propylaminophenyl)-3-(1-ethyl-2-methylindol-3-yl)-4-azaphthalide, 3-(2-methyl-4-di-n-hexylaminophenyl)-3-(1-n-octyl 3-(2-ethoxy-4-diethylaminophenyl)-3-(1-ethyl-2-methylindol-3-yl)-4-azaphthalide, 3,3-bis(2-ethoxy-4-diethylaminophenyl)-4-azaphthalide, 3,3-bis(1-n-octyl-2-methylindol-3-yl)-4-azaphthalide, 3-(2-ethoxy-4-diethylaminophenyl)-3-(1-ethyl-2-methylindol-3-yl)-4-azaphthalide, 3-(2-ethoxy-4-diethylaminophenyl)-3-(1-octyl-2-methylindol-3-yl)-4 or 7-azaphthalide, 3-( 2-ethoxy-4-diethylaminophenyl)-3-(1-ethyl-2-methylindol-3-yl)-4 or 7-azaphthalide, 3-(2-hexyloxy-4-diethylaminophenyl)-3-(1-ethyl-2-methylindol-3-yl)-4 or 7-azaphthalide, 3-(2-ethoxy-4-diethylaminophenyl)-3-(1-ethyl-2-phenylindol-3-yl)-4 or 7-azaphthalide, 3-(2-butoxy-4-diethylaminophenyl)-3-(1-ethyl-2-phenylindol-3 -yl)-4 or 7-azaphthalide 3-methyl-spiro-dinaphthopyran, 3-ethyl-spiro-dinaphthopyran, 3-phenyl-spiro-dinaphthopyran, 3-benzyl-spiro-dinaphthopyran, 3-methyl-naphtho-(3-methoxybenzo)spiropyran, 3-propyl-spiro-dibenzopyran-3,6-bis(dimethylamino)fluorene-9-spiro-3'-(6'-dimethylamino)phthalide, and other phthalides;

[0297] Other examples include 2'-anilino-6'-(N-ethyl-N-isopentyl)amino-3'-methylspiro[isobenzofuran-1(3H),9'-(9H)xanthene-3-one, 2'-anilino-6'-(N-ethyl-N-(4-methylphenyl))amino-3'-methylspiro[isobenzofuran-1(3H),9'-(9H)xanthene]-3-one, 3'-N,N-dibenzylamino-6'-N,N-diethylaminospiro[isobenzofuran-1(3H),9'-(9H)xanthene]-3-one, and 2'-(N-methyl-N-phenyl)amino-6'-(N-ethyl-N-(4-methylphenyl))aminospiro[isobenzofuran-1(3H),9'-(9H)xanthene]-3-one.

[0298] Among these, from the viewpoint of color development, the color former used in the present disclosure is preferably at least one compound selected from the group consisting of spiropyran compounds, spirooxazine compounds, spirolactone compounds, and spirolactam compounds. From the viewpoint of visibility, the hue of the dye after color development is preferably green, blue, or black.

[0299] Furthermore, from the viewpoints of color development and visibility of exposed areas, the acid color former is preferably a leuco dye. The leuco dye is not particularly limited as long as it has a leuco structure, but it is preferably a dye having a spiro structure, and more preferably a dye having a spirolactone ring structure. Furthermore, from the viewpoints of color development and visibility of exposed areas, the leuco dye is preferably a leuco dye having a phthalide structure or a fluoran structure. Furthermore, from the viewpoints of color development and visibility of exposed areas, the leuco dye having a phthalide structure or a fluoran structure is preferably a compound represented by any one of the following formulas (Le-1) to (Le-3), and more preferably a compound represented by the following formula (Le-2).

[0300]

[0301] In formulas (Le-1) to (Le-3), ERG each independently represents an electron-donating group; １ ~X ４each independently represents a hydrogen atom, a halogen atom, or a dialkylanilino group; X ５ ~X １０ each independently represents a hydrogen atom, a halogen atom, or a monovalent organic group; Y １ and Y ２ each independently represents C or N, Y １ If is N, then X １ does not exist, and Y ２ If is N, then X ４ does not exist, and Ra １ represents a hydrogen atom, an alkyl group, or an alkoxy group; Rb １ ~Rb ４ each independently represents a hydrogen atom, an alkyl group, an aryl group, or a heteroaryl group.

[0302] From the viewpoints of color development and visibility of exposed areas, the electron-donating group in ERG of formulae (Le-1) to (Le-3) is preferably an amino group, an alkylamino group, an arylamino group, a heteroarylamino group, a dialkylamino group, a monoalkylmonoarylamino group, a monoalkylmonoheteroarylamino group, a diarylamino group, a diheteroarylamino group, a monoarylmonoheteroarylamino group, an alkoxy group, an aryloxy group, a heteroaryloxy group, or an alkyl group; more preferably an amino group, an alkylamino group, an arylamino group, a heteroarylamino group, a dialkylamino group, a monoalkylmonoarylamino group, a monoalkylmonoheteroarylamino group, a diarylamino group, a diheteroarylamino group, a monoarylmonoheteroarylamino group, an alkoxy group, or an aryloxy group; still more preferably a monoalkylmonoarylamino group, a diarylamino group, a diheteroarylamino group, or a monoarylmonoheteroarylamino group; and particularly preferably a monoalkylmonoarylamino group. Furthermore, from the viewpoints of color development and visibility of exposed areas, the electron-donating group in the ERG is preferably a di-substituted amino group having an aryl group having a substituent at at least one ortho position or a heteroaryl group having a substituent at at least one ortho position, more preferably a di-substituted amino group having a phenyl group having a substituent at at least one ortho position and an electron-donating group at the para position, even more preferably an amino group having a phenyl group having a substituent at at least one ortho position and an electron-donating group at the para position, and an aryl group or heteroaryl group, and particularly preferably an amino group having a phenyl group having a substituent at at least one ortho position and an electron-donating group at the para position, and an aryl group having an electron-donating group or a heteroaryl group having an electron-donating group. Note that, in the present disclosure, the ortho position in an aryl group or heteroaryl group other than a phenyl group refers to the bonding position (e.g., the 2nd position, etc.) adjacent to the bonding position 1 of the aryl group or heteroaryl group to another structure.Furthermore, from the viewpoints of color development and visibility of exposed areas, the electron-donating group contained in the aryl group or heteroaryl group is preferably an amino group, an alkylamino group, an arylamino group, a heteroarylamino group, a dialkylamino group, a monoalkylmonoarylamino group, a monoalkylmonoheteroarylamino group, a diarylamino group, a diheteroarylamino group, a monoarylmonoheteroarylamino group, an alkoxy group, an aryloxy group, a heteroaryloxy group, or an alkyl group, more preferably an alkoxy group, an aryloxy group, a heteroaryloxy group, or an alkyl group, and particularly preferably an alkoxy group.

[0303] X in formulas (Le-1) to (Le-3) １ ~X ４ are each independently preferably a hydrogen atom or a chlorine atom, more preferably a hydrogen atom, from the viewpoint of color development and visibility of exposed areas. ５ ~X １０ are each independently, from the viewpoint of color development and visibility of exposed areas, preferably a hydrogen atom, a halogen atom, an alkyl group, an aryl group, an amino group, an alkylamino group, an arylamino group, a heteroarylamino group, a dialkylamino group, a monoalkylmonoarylamino group, a monoalkylmonoheteroarylamino group, a diarylamino group, a diheteroarylamino group, a monoarylmonoheteroarylamino group, a hydroxy group, an alkoxy group, an aryloxy group, a heteroaryloxy group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a heteroaryloxycarbonyl group, or a cyano group, more preferably a hydrogen atom, a halogen atom, an alkyl group, an aryl group, an alkoxy group, or an aryloxy group, still more preferably a hydrogen atom, a halogen atom, an alkyl group, or an aryl group, and particularly preferably a hydrogen atom. １ and Y ２ From the viewpoint of color development and visibility of exposed areas, it is preferable that at least one of the two is C, and Y １ and Y ２It is more preferable that both of Ra in formulas (Le-1) to (Le-3) are C. １ From the viewpoint of color development and visibility of exposed areas, Rb is preferably an alkyl group or an alkoxy group, more preferably an alkoxy group, and particularly preferably a methoxy group. １ ~Rb ４ are each independently preferably a hydrogen atom or an alkyl group, more preferably an alkyl group, and particularly preferably a methyl group, from the viewpoints of color development and visibility of exposed areas.

[0304] Furthermore, from the viewpoints of color development and visibility of exposed areas, the leuco dye having a phthalide structure or a fluoran structure is more preferably a compound represented by any one of the following formulas (Le-4) to (Le-6), and even more preferably a compound represented by the following formula (Le-5):

[0305] In formulas (Le-4) to (Le-6), ERG each independently represents an electron-donating group; １ ~X ４ each independently represents a hydrogen atom, a halogen atom, or a dialkylanilino group; Y １ and Y ２ each independently represents C or N, Y １ If is N, then X １ does not exist, and Y ２ If is N, then X ４ does not exist, and Ra １ represents a hydrogen atom, an alkyl group, or an alkoxy group; Rb １ ~Rb ４ each independently represents a hydrogen atom, an alkyl group, an aryl group, or a heteroaryl group.

[0306] ERG and X in formulas (Le-4) to (Le-6) １ ~X ４ , Y １ , Y ２ , Ra １ , and Rb １ ~Rb ４are ERG and X in formulas (Le-1) to (Le-3), respectively. １ ~X ４ , Y １ , Y ２ , Ra １ , and Rb １ ~Rb ４ The same applies to the preferred embodiments.

[0307] Furthermore, from the viewpoints of color development and visibility of exposed areas, the leuco dye having a phthalide structure or a fluoran structure is more preferably a compound represented by any one of the following formulas (Le-7) to (Le-9), and particularly preferably a compound represented by the following formula (Le-8):

[0308]

[0309] In formulas (Le-7) to (Le-9), X １ ~X ４ each independently represents a hydrogen atom, a halogen atom, or a dialkylanilino group; Y １ and Y ２ each independently represents C or N, Y １ If is N, then X １ does not exist, and Y ２ If is N, then X ４ does not exist, and Ra １ ~Ra ４ each independently represents a hydrogen atom, an alkyl group, or an alkoxy group; Rb １ ~Rb ４ each independently represents a hydrogen atom, an alkyl group, an aryl group, or a heteroaryl group; １ and Rc ２ each independently represents an aryl group or a heteroaryl group.

[0310] X in formulas (Le-7) to (Le-9) １ ~X ４ , Y １ and Y ２ represents X in formulas (Le-1) to (Le-3). １ ~X ４ , Y １ and Y ２The same applies to the preferred embodiments. １ ~Ra ４ are each independently preferably an alkyl group or an alkoxy group, more preferably an alkoxy group, and particularly preferably a methoxy group, from the viewpoints of color development and visibility of exposed areas. １ ~Rb ４ are each independently preferably a hydrogen atom or an aryl group substituted with an alkyl group or an alkoxy group, more preferably an alkyl group, and particularly preferably a methyl group, from the viewpoints of color development and visibility of exposed areas. １ and Rc ２ are each independently preferably a phenyl group or an alkylphenyl group, more preferably a phenyl group, from the viewpoints of color development and visibility of exposed areas. １ and Rc ２ are each independently, from the viewpoints of color development and visibility of exposed areas, preferably an aryl group having a substituent at at least one ortho position or a heteroaryl group having a substituent at at least one ortho position, more preferably an aryl group having a substituent at at least one ortho position, still more preferably a phenyl group having a substituent at at least one ortho position, and particularly preferably a phenyl group having a substituent at at least one ortho position and an electron-donating group at the para position. １ and Rc ２ In formula (Le-8), from the viewpoint of color development and visibility of exposed areas, X １ ~X ４ is a hydrogen atom, and Y １ and Y ２ is preferably C. Furthermore, in formula (Le-8), from the viewpoint of color development and visibility of exposed areas, it is preferable that Rb １ and Rb ２are each independently an aryl group substituted with an alkyl group or an alkoxy group. １ and Rb ２ are each independently preferably an aryl group or a heteroaryl group, more preferably an aryl group, further preferably an aryl group having an electron-donating group, and particularly preferably a phenyl group having an electron-donating group at the para position. １ , Rb ２ , Rc １ and Rc ２ From the viewpoints of color development and visibility of exposed areas, the electron-donating group in is preferably an amino group, an alkylamino group, an arylamino group, a heteroarylamino group, a dialkylamino group, a monoalkylmonoarylamino group, a monoalkylmonoheteroarylamino group, a diarylamino group, a diheteroarylamino group, a monoarylmonoheteroarylamino group, an alkoxy group, an aryloxy group, a heteroaryloxy group, or an alkyl group, more preferably an alkoxy group, an aryloxy group, a heteroaryloxy group, or an alkyl group, and particularly preferably an alkoxy group.

[0311] From the viewpoints of color development and visibility of exposed areas, the acid color former also preferably contains one or more compounds selected from the group consisting of compounds represented by the following formula (Le-10) and compounds represented by the following formula (Z-4): In other words, the image recording layer in the lithographic printing plate precursor according to the present disclosure preferably further contains one or more compounds selected from the group consisting of compounds represented by the following formula (Le-10) and compounds represented by the following formula (Z-4):

[0312]

[0313] In formula (Le-10), Ar １ each independently represents an aryl group or a heteroaryl group; Ar ２ each independently represents an aryl group having a substituent at at least one ortho-position, or a heteroaryl group having a substituent at at least one ortho-position.

[0314] Ar in formula (Le-10) １ represents Rb in formulas (Le-7) to (Le-9). １ and Rb ２ The same applies to the preferred embodiments of Ar in formula (Le-10). ２ is Rc in formulas (Le-7) to (Le-9). １ and Rc ２ The same applies to the preferred embodiments.

[0315] The alkyl group in formulas (Le-1) to (Le-9) may be linear, branched, or have a ring structure. The number of carbon atoms in the alkyl group in formulas (Le-1) to (Le-9) is preferably 1 to 20, more preferably 1 to 8, even more preferably 1 to 4, and particularly preferably 1 or 2. The number of carbon atoms in the aryl group in formulas (Le-1) to (Le-10) is preferably 6 to 20, more preferably 6 to 10, and particularly preferably 6 to 8. Specific examples of the aryl group in formulas (Le-1) to (Le-10) include a phenyl group, a naphthyl group, an anthracenyl group, and a phenanthrenyl group, each of which may have a substituent. Specific examples of the heteroaryl group in formulas (Le-1) to (Le-10) include a furyl group, a pyridyl group, a pyrimidyl group, a pyrazoyl group, and a thiophenyl group, each of which may have a substituent.

[0316] Furthermore, each of the monovalent organic groups, alkyl groups, aryl groups, heteroaryl groups, dialkylanilino groups, alkylamino groups, alkoxy groups, and the like in Formulae (Le-1) to (Le-10) may have a substituent. Examples of the substituent include an alkyl group, an aryl group, a heteroaryl group, a halogen atom, an amino group, an alkylamino group, an arylamino group, a heteroarylamino group, a dialkylamino group, a monoalkylmonoarylamino group, a monoalkylmonoheteroarylamino group, a diarylamino group, a diheteroarylamino group, a monoarylmonoheteroarylamino group, a hydroxy group, an alkoxy group, an aryloxy group, a heteroaryloxy group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a heteroaryloxycarbonyl group, and a cyano group. Furthermore, these substituents may be further substituted with other substituents.

[0317]

[0318] In formula (Z-4), Rza １ represents a hydrogen atom, an alkyl group, or an alkoxy group; Rzb １ ~Rb ４ each independently represents a hydrogen atom, an alkyl group, or an aryl group; Rzb １ and Rzb ２ , Rzb ３ and Rzb ４ may be linked to form a ring structure, X represents O or NR, R represents a hydrogen atom, an alkyl group, an aryl group, or a heteroaryl group, Y １ and Y ２ each independently represents CH or N.

[0319] Rza in formula (Z-4) １ is preferably an alkyl group or an alkoxy group. １ and Rzb ２ are each preferably independently an alkyl group. ３ and Rzb ４are each independently a hydrogen atom, an alkyl group, or an aryl group, and it is preferable that one of them is an aryl group. １ and Y ２ is preferably CH.

[0320] The alkyl group in formula (Z-4) may be linear, branched, or have a cyclic structure. The number of carbon atoms in the alkyl group in formula (Z-4) is preferably 1 to 20, more preferably 1 to 8, and even more preferably 1 to 5. The number of carbon atoms in the aryl group in formula (Z-4) is preferably 6 to 20, more preferably 6 to 10, and particularly preferably 6 to 8. Each group, such as the alkyl group or aryl group, in formula (Z-4) may have a substituent. Examples of the substituent include an alkyl group, an aryl group, a halogen atom, an amino group, an alkylamino group, an arylamino group, a dialkylamino group, a monoalkylmonoarylamino group, a diarylamino group, a hydroxy group, an alkoxy group, an aryloxy group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, and a cyano group. Furthermore, these substituents may be further substituted with other substituents.

[0321] Suitable leuco dyes having a phthalide structure or a fluoran structure include the following compounds: wherein Me represents a methyl group.

[0322]

[0323]

[0324]

[0325]

[0326]

[0327]

[0328]

[0329]

[0330] As the color former, commercially available products can be used, such as ETAC, RED500, RED520, CVL, S-205, BLACK305, BLACK400, BLACK100, BLACK500, H-7001, GREEN300, NIRBLACK78, BLUE220, H-3035, BLUE203, ATP, H-1046, and H-2114 (all manufactured by Fukui Yamada Chemical Co., Ltd.), ORANGE-DCF, and Vermilion. Examples of such dyes include n-DCF, PINK-DCF, RED-DCF, BLMB, CVL, GREEN-DCF, and TH-107 (all manufactured by Hodogaya Chemical Co., Ltd.), ODB, ODB-2, ODB-4, ODB-250, ODB-Black XV, Blue-63, Blue-502, GN-169, GN-2, Green-118, Red-40, and Red-8 (all manufactured by Yamamoto Chemical Industry Co., Ltd.), and crystal violet lactone (manufactured by Tokyo Chemical Industry Co., Ltd.). Among these commercially available products, ETAC, S-205, BLACK 305, BLACK 400, BLACK 100, BLACK 500, H-7001, GREEN 300, NIRBLACK 78, H-3035, ATP, H-1046, H-2114, GREEN-DCF, Blue-63, GN-169, and crystal violet lactone are preferred because the films they form have good visible light absorptance.

[0331] These color formers may be used alone or in combination of two or more. The content of the color former is preferably 0.5% by mass to 10% by mass, and more preferably 1% by mass to 5% by mass, based on the total mass of the image recording layer.

[0332] <Polymerizable Compound> The image recording layer preferably contains a polymerizable compound. In the present disclosure, a polymerizable compound refers to a compound having a polymerizable group. The polymerizable group is not particularly limited as long as it is a known polymerizable group, but is preferably an ethylenically unsaturated group. The polymerizable group may be either a radically polymerizable group or a cationically polymerizable group, but is preferably a radically polymerizable group. Examples of the radically polymerizable group include a (meth)acryloyl group, an allyl group, a vinylphenyl group, and a vinyl group, and from the viewpoint of reactivity, a (meth)acryloyl group is preferred. The molecular weight of the polymerizable compound (weight average molecular weight when the polymerizable compound has a molecular weight distribution) is preferably 50 or more and less than 2,500.

[0333] The polymerizable compound may be, for example, a radically polymerizable compound or a cationically polymerizable compound, but is preferably an addition-polymerizable compound (ethylenically unsaturated compound) having at least one ethylenically unsaturated bond. The ethylenically unsaturated compound is preferably a compound having at least one terminal ethylenically unsaturated bond, and more preferably a compound having two or more terminal ethylenically unsaturated bonds. The polymerizable compound has a chemical form such as a monomer, a prepolymer, i.e., a dimer, trimer, or oligomer, or a mixture thereof. Among these, from the viewpoint of printing durability, the polymerizable compound preferably contains a trifunctional or higher functional polymerizable compound, more preferably a heptafunctional or higher functional polymerizable compound, and even more preferably a decafunctional or higher functional polymerizable compound. Furthermore, from the viewpoint of printing durability of the resulting lithographic printing plate, the polymerizable compound preferably contains a trifunctional or higher functional ethylenically unsaturated compound (preferably a heptafunctional or higher functional compound, more preferably a decafunctional or higher functional (meth)acrylate compound).

[0334] From the viewpoints of on-press developability and stain suppression, the polymerizable compound preferably contains a difunctional or lower polymerizable compound, more preferably a difunctional polymerizable compound, and particularly preferably a difunctional (meth)acrylate compound. From the viewpoints of printing durability, on-press developability, and stain suppression, the content of the difunctional or lower polymerizable compound (preferably a bifunctional polymerizable compound) is preferably 5% by mass to 100% by mass, more preferably 10% by mass to 100% by mass, and particularly preferably 15% by mass to 100% by mass, relative to the total mass of the polymerizable compounds in the image recording layer.

[0335] The polymerizable compound preferably contains polymer BB. Polymer BB has a structural unit (Bb1) represented by the following formula (BI).

[0336]

[0337] In formula (BI), R Ｂ１１ and R Ｂ１２ each independently represents a hydrogen atom or an alkyl group, R Ｂ１３ represents a hydrogen atom or a monovalent substituent, L Ｂ１１ and L Ｂ１２ each independently represents a single bond or a divalent linking group, and Rh represents a substituent containing two or more silicon atoms.

[0338] R Ｂ１１ and R Ｂ１２ Examples of the alkyl group represented by the formula (I) include linear alkyl groups having 1 to 18 carbon atoms, and branched or cyclic alkyl groups having 3 to 18 carbon atoms. Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, an isopropyl group, a tert-butyl group, and a cyclohexyl group. R Ｂ１１ and R Ｂ１２ are preferably all hydrogen atoms.

[0339] R Ｂ１３ Examples of the monovalent substituent represented by the formula (I) include an alkyl group, an alkenyl group, and an aryl group. The alkyl group, the alkenyl group, and the aryl group can be represented by the formula (I) １ , R ２ , and R ３The preferred embodiments are the same as those of the alkyl group, alkenyl group, and aryl group represented by R ６ is preferably a hydrogen atom or a methyl group.

[0340] L Ｂ１１ Examples of the divalent linking group represented by the formula (I) include -C(=O)-O- (a so-called ester bond) and -C(=O)-NH-. Ｂ１１ The divalent linking group represented by the formula: is preferably an ester bond, -C(=O)-O-.

[0341] L Ｂ１２ The divalent linking group represented by L Ｂ１１ There are no particular limitations on L as long as it is a group that can link L to Rh. Ｂ１２ Examples of the divalent linking group represented by the formula (I) include an alkylene group. The alkylene group is preferably an alkylene group having 2 to 10 carbon atoms, and more preferably an alkylene group having 4 to 8 carbon atoms.

[0342] The substituent containing two or more silicon atoms, represented by Rh, is not particularly limited as long as two or more silicon atoms are contained in the atomic group constituting the substituent. From the viewpoint of on-press developability, the substituent containing two or more silicon atoms preferably contains the silicon atoms as silicon-oxygen bonds (Si—O bonds). The substituent containing two or more silicon atoms preferably has two or more silicon-oxygen bonds, preferably three or more, and preferably 3 to 12. The substituent containing two or more silicon atoms preferably contains the silicon-oxygen bonds as a polysiloxane structure. Furthermore, from the viewpoint of on-press developability, the substituent containing two or more silicon atoms preferably has a branched structure, and more preferably has a branched structure branched around the silicon atom.

[0343] Specifically, the substituent containing two or more silicon atoms is preferably a group containing two or more structures represented by the following formula (BIa).

[0344]

[0345] In the above formula (BIa), * represents a bonding position, and R ｂ１１ , Rｂ１２ , and R ｂ１３ each independently represents an alkyl group, an alkenyl group, an aryl group, or an alkylenearyl group.

[0346] R ｂ１１ , R ｂ１２ , and R ｂ１３ Examples of the alkyl group represented by the formula (I) include linear alkyl groups having 1 to 18 carbon atoms, and branched or cyclic alkyl groups having 3 to 18 carbon atoms. Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, an isopropyl group, a tert-butyl group, and a cyclohexyl group. R ｂ１１ , R ｂ１２ , and R ｂ１３ Examples of the alkenyl group represented by the formula (I) include alkenyl groups having 2 to 12 carbon atoms. Specific examples of the alkenyl group include vinyl, 1-propenyl, 1-butenyl, 1-methyl-1-propenyl, 1-cyclopentenyl, and 1-cyclohexenyl groups. ｂ１１ , R ｂ１２ , and R ｂ１３ Examples of the aryl group represented by the formula (I) include aryl groups having 6 to 12 carbon atoms. Specific examples of the aryl group include a phenyl group, an α-methylphenyl group, and a naphthyl group. ｂ１１ , R ｂ１２ , and R ｂ１３ Examples of the alkylenearyl group represented by the formula (I) include alkylenearyl groups having 7 to 30 carbon atoms.

[0347] In formula (BIa), R ｂ１１ , R ｂ１２ , and R ｂ１３ are each independently preferably an alkyl group, more preferably all the same alkyl group, even more preferably all alkyl groups having 1 to 4 carbon atoms, and particularly preferably all methyl groups.

[0348] The substituent containing two or more silicon atoms is preferably a group containing three or more structures represented by the above formula (BIa), and more preferably a group containing three to six of them.

[0349] The substituent containing two or more silicon atoms is preferably a group represented by the following formula (Ba2).

[0350] In the above formula (Ba2), * represents a bonding position, and R ｂ１ , R ｂ２ , and R ｂ３ R each independently represents an alkyl group, an alkenyl group, an aryl group, or an alkylenearyl group. ｂ１ , R ｂ２ , and R ｂ３ Examples of the alkyl group represented by the formula (I) include linear alkyl groups having 1 to 18 carbon atoms, and branched or cyclic alkyl groups having 3 to 18 carbon atoms. Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, an isopropyl group, a tert-butyl group, and a cyclohexyl group. R ｂ１ , R ｂ２ , and R ｂ３ Examples of the alkenyl group represented by the formula (I) include alkenyl groups having 2 to 12 carbon atoms. Specific examples of the alkenyl group include vinyl, 1-propenyl, 1-butenyl, 1-methyl-1-propenyl, 1-cyclopentenyl, and 1-cyclohexenyl groups. ｂ１ , R ｂ２ , and R ｂ３ Examples of the aryl group represented by the formula (I) include aryl groups having 6 to 12 carbon atoms. Specific examples of the aryl group include a phenyl group, an α-methylphenyl group, and a naphthyl group. ｂ１ , R ｂ２ , and R ｂ３ Examples of the alkylenearyl group represented by the formula (I) include alkylenearyl groups having 7 to 30 carbon atoms.

[0351] In formula (Ba2), R ｂ１ , R ｂ２ , and R ｂ３ are each independently preferably an alkyl group, more preferably all the same alkyl group, even more preferably all alkyl groups having 1 to 4 carbon atoms, and particularly preferably all methyl groups.

[0352] Specific examples of the structural unit (Bb1) represented by formula (BI) include the monomers represented by K-1 to K-12. Specific examples of the monomer unit that forms the structural unit having a substituent containing two or more silicon atoms in its side chain are not limited to these. In the following structures, n is an integer of 2 to 1000.

[0353]

[0354] From the viewpoint of obtaining better on-press developability, the polymerizable BB is preferably a copolymer containing a structural unit having a substituent containing two or more silicon atoms in a side chain and a structural unit having a hydrophilic group in a side chain.

[0355] The structural unit having a hydrophilic group on the side chain contained in the polymerizable BB is preferably a structural unit represented by the following formula (a4).

[0356]

[0357] In formula (Ba4), R Ｂ７ and R Ｂ８ each independently represents a hydrogen atom or an alkyl group, R Ｂ９ represents a hydrogen atom or a monovalent substituent, L Ｂ２ represents —C(═O)—O— or —C(═O)—NH—, L Ｂ２ and L Ｂ３ represents a single bond or a divalent linking group, X Ｂ represents a hydrophilic group.

[0358] R Ｂ７ and R Ｂ８ The alkyl group represented by R ４ and R ５ R each independently represents a hydrogen atom or an alkyl group. Ｂ７ and R Ｂ８ Examples of the alkyl group represented by the formula (I) include linear alkyl groups having 1 to 18 carbon atoms, and branched or cyclic alkyl groups having 3 to 18 carbon atoms. Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, an isopropyl group, a tert-butyl group, and a cyclohexyl group. R Ｂ７ and R Ｂ８ are preferably all hydrogen atoms.

[0359] R Ｂ９ Examples of the monovalent substituent represented by the formula (I) include an alkyl group, an alkenyl group, and an aryl group. The alkyl group, the alkenyl group, and the aryl group can be represented by the formula (I) Ｂ１１ , R Ｂ１２ , and R Ｂ１３ The preferred embodiments are the same as those of the alkyl group, alkenyl group, and aryl group represented by R Ｂ９ is preferably a hydrogen atom or a methyl group.

[0360] L Ｂ３ The divalent linking group represented by L Ｂ２ and X Ｂ There are no particular limitations on the group, as long as it can link L Ｂ３ Examples of the divalent linking group represented by the formula (I) include an alkylene group. The alkylene group is preferably an alkylene group having 2 to 10 carbon atoms, and more preferably an alkylene group having 4 to 8 carbon atoms.

[0361] X Ｂ Examples of the hydrophilic group represented by the formula (I) include a hydroxyl group, a phosphate group, a polyalkyleneoxy group, or a group combining two or more of these. Here, examples of the polyalkyleneoxy group include a polyethyleneoxy group, a polypropyleneoxy group, a polybutyleneoxy group, or a group combining these.

[0362] Specific examples of monomer units for forming a structural unit having a hydrophilic group on a side chain include monomers represented by H-1 to H-40. Specific examples of monomer units for forming a structural unit having a hydrophilic group on a side chain are not limited to these. In the following structures, n and m each independently represent an integer of 2 to 100. In the following structures, the term "random" means that multiple types of polyalkyleneoxy groups are arranged randomly.

[0363]

[0364]

[0365] The polymer BB may contain one type of structural unit having a substituent containing two or more silicon atoms in its side chain, or two or more types. In the polymer BB, the content of the structural unit having a substituent containing two or more silicon atoms in its side chain may be 100% by mass, preferably 15% to 70% by mass, more preferably 20% to 60% by mass, and even more preferably 25% to 50% by mass, relative to the mass of the polymer BB. Furthermore, the polymer BB may contain one type of structural unit having a hydrophilic group in its side chain, or two or more types. In the polymer BB, the content of the structural unit having a hydrophilic group in its side chain is preferably 30% to 85% by mass, more preferably 40% to 80% by mass, and even more preferably 50% to 75% by mass, relative to the mass of the polymer BB.

[0366] The polymer BB may further contain other structural units. Examples of such structural units include structural units having a carboxylic acid group on the side chain. Examples of structural units having a carboxylic acid group on the side chain include (meth)acrylic acid, itaconic acid, and itaconic acid derivatives. The structural unit having a carboxylic acid group on the side chain is preferably included as a structural unit separate from the structural unit having a hydrophilic group on the side chain described above. Examples of such structural units include alkyl (meth)acrylate (the alkyl group has 1 to 24 carbon atoms), styrene derivatives, maleic anhydride, maleimide anhydride, (meth)acrylonitrile, vinyl ether derivatives, and alkyl (meth)acrylamide derivatives. In the polymer BB, the content of such other structural units is preferably 0% by mass to 20% by mass relative to the mass of the polymer BB.

[0367] The weight average molecular weight of the polymer BB is preferably from 5,000 to 100,000, more preferably from 8,000 to 60,000, from the viewpoint of obtaining an image recording layer with excellent surface condition.

[0368] Specific examples of the polymer BB include BP-1 to BP-10 shown below, but the specific examples of the polymer BB are not limited to these.

[0369]

[0370] The content of polymer BB is preferably 0.001% by mass to 0.1% by mass, and more preferably 0.002% by mass to 0.01% by mass, based on the total mass of the image recording layer coating liquid.

[0371] (Oligomer) The polymerizable compound contained in the image recording layer preferably contains a polymerizable compound that is an oligomer (hereinafter also simply referred to as "oligomer"). In the present disclosure, an oligomer refers to a polymerizable compound having a molecular weight (weight average molecular weight when the molecular weight distribution is present) of 600 to 15,000 and containing at least one polymerizable group. From the viewpoint of excellent chemical resistance and printing durability, the molecular weight of the oligomer is preferably 1,000 to 15,000.

[0372] Furthermore, from the viewpoint of improving printing durability, the number of polymerizable groups in one molecule of the oligomer is preferably 2 or more, more preferably 3 or more, even more preferably 6 or more, and particularly preferably 10 or more. Furthermore, there is no particular upper limit to the number of polymerizable groups in the oligomer, but the number of polymerizable groups is preferably 20 or less.

[0373] From the viewpoints of printing durability and on-press developability, the oligomer preferably has 7 or more polymerizable groups and a molecular weight of 1,000 to 15,000, and more preferably has 7 or more polymerizable groups and a molecular weight of 1,000 to 15,000. The oligomer may contain polymer components that may be generated during the production process of the oligomer.

[0374] From the viewpoints of printing durability, visibility, and on-press developability, the oligomer preferably contains at least one selected from the group consisting of a compound having a urethane bond, a compound having an ester bond, and a compound having an epoxy residue, and more preferably contains a compound having a urethane bond. In the present disclosure, the epoxy residue refers to a structure formed by an epoxy group, and means, for example, a structure similar to the structure obtained by the reaction of an acid group (such as a carboxylic acid group) with an epoxy group.

[0375] The compound having a urethane bond, which is an example of the oligomer, is preferably, for example, a compound having at least a group represented by the following formula (Ac-1) or formula (Ac-2), and more preferably a compound having at least a group represented by the following formula (Ac-1).

[0376]

[0377] In formula (Ac-1) and formula (Ac-2), L １ ~L ４ Each independently represents a divalent hydrocarbon group having 2 to 20 carbon atoms, and the wavy line represents the bonding position to other structures. １ ~L ４ are each independently preferably an alkylene group having 2 to 20 carbon atoms, more preferably an alkylene group having 2 to 10 carbon atoms, and even more preferably an alkylene group having 4 to 8 carbon atoms. The alkylene group may have a branched or cyclic structure, but is preferably a linear alkylene group.

[0378] It is preferred that the wavy line portions in formula (Ac-1) or formula (Ac-2) are each independently directly bonded to the wavy line portions in the groups represented by formula (Ae-1) or formula (Ae-2) below.

[0379]

[0380] In formula (Ae-1) and formula (Ae-2), R each independently represents an acryloyloxy group or a methacryloyloxy group, and the wavy line portion represents the bonding position to the wavy line portion in formula (Ac-1) and formula (Ac-2).

[0381] Alternatively, the compound having a urethane bond may be a compound obtained by introducing a polymerizable group into a polyurethane obtained by reacting a polyisocyanate compound with a polyol compound through a polymer reaction. For example, a compound having a urethane bond may be obtained by reacting a polyurethane oligomer obtained by reacting a polyol compound having an acid group with a polyisocyanate compound with a compound having an epoxy group and a polymerizable group.

[0382] The number of polymerizable groups in the compound having an ester bond, which is an example of an oligomer, is preferably 3 or more, and more preferably 6 or more.

[0383] As a compound having an epoxy residue, which is an example of an oligomer, a compound containing a hydroxy group is preferred. The number of polymerizable groups in the compound having an epoxy residue is preferably 2 to 6, and more preferably 2 to 3. The compound having an epoxy residue can be obtained, for example, by reacting a compound having an epoxy group with acrylic acid.

[0384] Specific examples of oligomers are shown in the table below, but the oligomers used in the present disclosure are not limited to these. Commercially available oligomers may be used, and examples thereof include UA510H, UA-306H, UA-306I, and UA-306T (all manufactured by Kyoeisha Chemical Co., Ltd.), UV-1700B, UV-6300B, and UV7620EA (all manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), U-15HA (manufactured by Shin-Nakamura Chemical Co., Ltd.), EBECRYL450, EBECRYL657, EBECRYL885, EBECRYL800, EBECRYL3416, and EBECRYL860 (all manufactured by Daicel Allnex Corporation), but are not limited thereto.

[0385] From the viewpoint of improving chemical resistance, printing durability, and suppression of on-press development residue, the content of the oligomer is preferably 30% by mass to 100% by mass, more preferably 50% by mass to 100% by mass, and even more preferably 80% by mass to 100% by mass, relative to the total mass of the polymerizable compounds in the image recording layer.

[0386] (Low Molecular Weight Polymerizable Compound) The polymerizable compound may further contain a polymerizable compound other than the oligomer. From the viewpoint of chemical resistance, the polymerizable compound other than the oligomer is preferably a low molecular weight polymerizable compound. The low molecular weight polymerizable compound may be in a chemical form such as a monomer, a dimer, a trimer, or a mixture thereof. Furthermore, from the viewpoint of chemical resistance, the low molecular weight polymerizable compound is preferably at least one polymerizable compound selected from the group consisting of polymerizable compounds having three or more ethylenically unsaturated groups and polymerizable compounds having an isocyanuric ring structure.

[0387] In the present disclosure, a low-molecular-weight polymerizable compound refers to a polymerizable compound having a molecular weight (weight-average molecular weight when the compound has a molecular weight distribution) of 50 or more and less than 600. From the viewpoint of achieving excellent chemical resistance, printing durability, and on-press development residue suppression, the molecular weight of the low-molecular-weight polymerizable compound is preferably 100 or more and less than 600, more preferably 300 or more and less than 600, and even more preferably 400 or more and less than 600.

[0388] When the polymerizable compound contains a low-molecular-weight polymerizable compound as a polymerizable compound other than an oligomer (when two or more types of low-molecular-weight polymerizable compounds are contained, the total amount of the low-molecular-weight polymerizable compounds), from the viewpoints of chemical resistance, printing durability, and suppression of on-press development residue, the ratio of the oligomer to the low-molecular-weight polymerizable compound (oligomer / low-molecular-weight polymerizable compound) is preferably 10 / 1 to 1 / 10, more preferably 10 / 1 to 3 / 7, and even more preferably 10 / 1 to 7 / 3, by mass.

[0389] In addition, as the low molecular weight polymerizable compound, the polymerizable compounds described in paragraphs 0082 to 0086 of WO 2019 / 013268 can also be suitably used.

[0390] The details of the method of use, such as the structure of the polymerizable compound, whether it is used alone or in combination, and the amount added, can be set as desired. In particular, from the viewpoint of printing durability, it is preferable that the image recording layer contains two or more types of polymerizable compounds. The content of the polymerizable compounds (when two or more types of polymerizable compounds are contained, the total content of the polymerizable compounds) is preferably 5% by mass to 75% by mass, more preferably 10% by mass to 70% by mass, and even more preferably 15% by mass to 60% by mass, relative to the total mass of the image recording layer.

[0391] <Particles> The image recording layer preferably contains particles. The particles may be organic particles or inorganic particles, but from the viewpoint of printing durability, it is preferable to contain organic particles, and it is more preferable to contain polymer particles. As the inorganic particles, known inorganic particles can be used, and metal oxide particles such as silica particles and titania particles can be preferably used.

[0392] The polymer particles are preferably selected from the group consisting of thermoplastic resin particles, thermoreactive resin particles, polymer particles having polymerizable groups, microcapsules encapsulating hydrophobic compounds, and microgels (e.g., crosslinked polymer particles). Among these, polymer particles or microgels having polymerizable groups are preferred. In a particularly preferred embodiment, the polymer particles contain at least one ethylenically unsaturated polymerizable group. The presence of such polymer particles has the effect of improving the printing durability of exposed areas and the on-press developability of unexposed areas. Furthermore, from the viewpoints of printing durability and on-press developability, the polymer particles are preferably thermoplastic resin particles.

[0393] Preferred examples of thermoplastic resin particles include thermoplastic polymer particles described in Research Disclosure No. 33303 published in January 1992, JP-A-9-123387, JP-A-9-131850, JP-A-9-171249, JP-A-9-171250, and European Patent No. 931647. Specific examples of polymers constituting the thermoplastic resin particles include homopolymers or copolymers of monomers such as ethylene, styrene, vinyl chloride, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, vinylidene chloride, acrylonitrile, vinylcarbazole, and acrylates or methacrylates having a polyalkylene structure, as well as mixtures thereof. Preferred examples include copolymers containing polystyrene, styrene, and acrylonitrile, or polymethyl methacrylate. The average particle size of the thermoplastic resin particles is preferably 0.01 μm to 3.0 μm.

[0394] The thermoreactive resin particles include polymer particles having thermoreactive groups, which form hydrophobic regions due to crosslinking caused by a thermal reaction and the resulting change in functional groups.

[0395] The thermally reactive group in the polymer particles having a thermally reactive group may be any functional group that undergoes any reaction as long as a chemical bond is formed, but is preferably a polymerizable group, and preferred examples thereof include ethylenically unsaturated groups that undergo radical polymerization reactions (e.g., acryloyl groups, methacryloyl groups, vinyl groups, allyl groups, etc.), cationically polymerizable groups (e.g., vinyl groups, vinyloxy groups, epoxy groups, oxetanyl groups, etc.), isocyanato groups or their block products that undergo addition reactions, epoxy groups, vinyloxy groups, and functional groups having active hydrogen atoms that are their reaction partners (e.g., amino groups, hydroxy groups, carboxy groups, etc.), carboxy groups that undergo condensation reactions, and their reaction partners, hydroxy groups or amino groups, and acid anhydrides that undergo ring-opening addition reactions, and their reaction partners, amino groups or hydroxy groups.

[0396] As for the microcapsules, as described in, for example, JP-A Nos. 2001-277740 and 2001-277742, at least some of the components of the image recording layer are encapsulated in the microcapsules. The components of the image recording layer can also be contained outside the microcapsules. In a preferred embodiment, the image recording layer containing microcapsules has a hydrophobic component encapsulated in the microcapsules and a hydrophilic component contained outside the microcapsules.

[0397] The microgel (e.g., crosslinked polymer particles) can contain a part of the components of the image recording layer on at least one of its surface and interior. In particular, a reactive microgel having a radically polymerizable group on its surface is preferred from the viewpoints of the sensitivity of the resulting lithographic printing plate precursor and the printing durability of the resulting lithographic printing plate.

[0398] Known methods can be used to microencapsulate or microgel the components of the image recording layer.

[0399] Furthermore, from the viewpoint of the printing durability, stain resistance, and storage stability of the resulting lithographic printing plate, the polymer particles are preferably those obtained by reacting a polyisocyanate compound, which is an adduct of a polyphenol compound having two or more hydroxy groups in its molecule with isophorone diisocyanate, with a compound having active hydrogen. The polyphenol compound is preferably a compound having multiple benzene rings each having a phenolic hydroxy group. The compound having active hydrogen is preferably a polyol compound or a polyamine compound, more preferably a polyol compound, and even more preferably at least one compound selected from the group consisting of propylene glycol, glycerin, and trimethylolpropane. Examples of resin particles obtained by reacting a polyisocyanate compound, which is an adduct of a polyphenol compound having two or more hydroxy groups in its molecule with isophorone diisocyanate, with a compound having active hydrogen include the polymer particles described in paragraphs

[0032] to

[0095] of JP-A-2012-206495.

[0400] Furthermore, from the viewpoint of the printing durability and solvent resistance of the resulting lithographic printing plate, the polymer particles preferably have a hydrophobic main chain and include both i) a constituent unit having a pendant cyano group directly bonded to the hydrophobic main chain, and ii) a constituent unit having a pendant group containing a hydrophilic polyalkylene oxide segment. A preferred example of the hydrophobic main chain is an acrylic resin chain. Examples of the pendant cyano group include -[CH ２ CH(C≡N)]- or -[CH ２ C(CH ３ )(C≡N)]— is preferred. The structural unit having a pendant cyano group can be easily derived from an ethylenically unsaturated monomer, such as acrylonitrile or methacrylonitrile, or a combination thereof. The alkylene oxide in the hydrophilic polyalkylene oxide segment is preferably ethylene oxide or propylene oxide, and more preferably ethylene oxide. The number of repeating alkylene oxide structures in the hydrophilic polyalkylene oxide segment is preferably 10 to 100, more preferably 25 to 75, and even more preferably 40 to 50. Preferred examples of resin particles having a hydrophobic main chain and including both i) a structural unit having a pendant cyano group directly bonded to the hydrophobic main chain, and ii) a structural unit having a pendant group including a hydrophilic polyalkylene oxide segment include those described in paragraphs 0039 to 0068 of JP-T-2008-503365.

[0401] Further, from the viewpoints of printing durability and on-press developability, the polymer particles preferably have a hydrophilic group. The hydrophilic group is not particularly limited as long as it has a hydrophilic structure, and examples thereof include an acid group such as a carboxy group, a hydroxy group, an amino group, a cyano group, and a polyalkylene oxide structure. Among these, from the viewpoints of on-press developability and printing durability, a polyalkylene oxide structure is preferred, and a polyethylene oxide structure, a polypropylene oxide structure, or a polyethylene / propylene oxide structure is more preferred. Further, from the viewpoints of on-press developability and suppression of development residue during on-press development, the polyalkylene oxide structure preferably has a polypropylene oxide structure, and more preferably has a polyethylene oxide structure or a polypropylene oxide structure. Further, from the viewpoints of printing durability, ink receptivity, and on-press developability, the hydrophilic group preferably contains a structural unit having a cyano group or a group represented by the following formula Z, more preferably contains a structural unit represented by the following formula (AN) or a group represented by the following formula Z, and particularly preferably contains a group represented by the following formula Z: *-Q-W-Y Formula Z In Formula Z, Q represents a divalent linking group, W represents a divalent group having a hydrophilic structure or a divalent group having a hydrophobic structure, Y represents a monovalent group having a hydrophilic structure or a monovalent group having a hydrophobic structure, either W or Y has a hydrophilic structure, and * represents a bonding site with another structure.

[0402]

[0403] In formula (AN), R ＡＮ represents a hydrogen atom or a methyl group.

[0404] From the viewpoint of printing durability, the polymer contained in the polymer particles preferably contains a structural unit formed by a compound having a cyano group. The cyano group is typically introduced into the resin as a structural unit containing a cyano group using a compound (e.g., a monomer) having a cyano group. Examples of compounds having a cyano group include acrylonitrile compounds, with (meth)acrylonitrile being preferred. The structural unit containing a cyano group is preferably a structural unit formed by an acrylonitrile compound, and more preferably a structural unit formed by (meth)acrylonitrile, i.e., a structural unit represented by the above formula (AN). When the polymer contains a polymer having a structural unit containing a cyano group, the content of the structural unit containing a cyano group, preferably the structural unit represented by the above formula (AN), in the polymer having the structural unit containing a cyano group is preferably 5% to 90% by mass, more preferably 20% to 80% by mass, and particularly preferably 30% to 60% by mass, relative to the total mass of the polymer having the structural unit containing a cyano group, from the viewpoint of printing durability.

[0405] Furthermore, from the viewpoints of printing durability, ink receptivity, and on-press developability, the polymer particles preferably contain polymer particles having a group represented by the formula Z above.

[0406] Q in the above formula Z is preferably a divalent linking group having 1 to 20 carbon atoms, and more preferably a divalent linking group having 1 to 10 carbon atoms. Furthermore, Q in the above formula Z is preferably an alkylene group, an arylene group, an ester bond, an amide bond, or a group consisting of a combination of two or more of these, and more preferably a phenylene group, an ester bond, or an amide bond.

[0407] The divalent group having a hydrophilic structure in W of the above formula Z is a polyalkyleneoxy group or a polyalkyleneoxy group having —CH ２ CH ２ NR Ｗ It is preferable that R Ｗrepresents a hydrogen atom or an alkyl group. The divalent group having a hydrophobic structure represented by W in the above formula Z is —R ＷＡ -, -O-R ＷＡ -O-, -R Ｗ N-R ＷＡ -NR Ｗ -, -OC(=O)-R ＷＡ —O— or —OC(═O)—R ＷＡ It is preferable that R is —O—. ＷＡ each independently represents a linear, branched, or cyclic alkylene group having 6 to 120 carbon atoms, a haloalkylene group having 6 to 120 carbon atoms, an arylene group having 6 to 120 carbon atoms, an alkylylene group having 6 to 120 carbon atoms (i.e., a divalent group obtained by removing one hydrogen atom from an alkylaryl group), or an aralkylene group having 6 to 120 carbon atoms.

[0408] The monovalent group having a hydrophilic structure in Y of the above formula Z is -OH, -C(=O)OH, a polyalkyleneoxy group having a hydrogen atom or an alkyl group at the end, or a polyalkyleneoxy group having a hydrogen atom or an alkyl group at the other end and -CH ２ CH ２ N (R Ｗ The monovalent group having a hydrophobic structure represented by Y in the above formula Z is preferably a linear, branched or cyclic alkyl group having 6 to 120 carbon atoms, a haloalkyl group having 6 to 120 carbon atoms, an aryl group having 6 to 120 carbon atoms, an alkaryl group (alkylaryl group) having 7 to 120 carbon atoms, an aralkyl group having 7 to 120 carbon atoms, -OR ＷＢ , -C(=O)OR ＷＢ , or —OC(═O)R ＷＢ It is preferable that R ＷＢ represents an alkyl group having 6 to 20 carbon atoms.

[0409] In terms of printing durability, ink receptivity, and on-press developability, it is more preferable that the polymer particles having a group represented by the above formula Z are such that W is a divalent group having a hydrophilic structure, Q is a phenylene group, an ester bond, or an amide bond, W is a polyalkyleneoxy group, and Y is a polyalkyleneoxy group whose terminal is a hydrogen atom or an alkyl group.

[0410] Furthermore, from the viewpoints of printing durability and on-press developability, the polymer particles preferably contain polymer particles having a polymerizable group, and more preferably contain polymer particles having a polymerizable group on the particle surface. Furthermore, from the viewpoint of printing durability, the polymer particles preferably contain polymer particles having a hydrophilic group and a polymerizable group. The polymerizable group may be a cationically polymerizable group or a radically polymerizable group, but from the viewpoint of reactivity, a radically polymerizable group is preferable. The polymerizable group is not particularly limited as long as it is a polymerizable group, but from the viewpoint of reactivity, an ethylenically unsaturated group is preferable, a vinylphenyl group (styryl group), a (meth)acryloxy group, or a (meth)acrylamide group is more preferable, and a (meth)acryloxy group is particularly preferable. Furthermore, the polymer in the polymer particles having a polymerizable group preferably has a structural unit having a polymerizable group. Furthermore, a polymerizable group may be introduced onto the surface of the polymer particle by a polymer reaction.

[0411]

[0033] Furthermore, from the viewpoints of printing durability and on-press developability, the image recording layer preferably contains addition polymerization resin particles having a dispersible group as the polymer particles, and it is more preferable that the dispersible group contains a group represented by the above formula Z.

[0412] Furthermore, from the viewpoints of printing durability, ink receptivity, on-press developability, and suppression of development residue during on-press development, the polymer particles preferably contain a resin having a urea bond, more preferably contain a resin having a structure obtained by at least reacting an isocyanate compound represented by the following formula (Iso) with water, and particularly preferably contain a resin having a structure obtained by at least reacting an isocyanate compound represented by the following formula (Iso) with water, and having a polyethylene oxide structure and a polypropylene oxide structure as the polyoxyalkylene structure. Furthermore, the particles containing the resin having a urea bond are preferably microgels.

[0413]

[0414] In formula (Iso), n represents an integer of 0 to 10.

[0415] An example of a reaction between an isocyanate compound represented by the above formula (Iso) and water is the reaction shown below. Note that the following example uses the 4,4-isomer, where n = 0. As shown below, when an isocyanate compound represented by the above formula (Iso) is reacted with water, some of the isocyanate groups are hydrolyzed by the water to generate amino groups. The resulting amino groups then react with the isocyanate groups to form urea bonds and a dimer. Furthermore, the following reaction is repeated to form a resin having a urea bond. Furthermore, by adding a compound reactive with isocyanate groups (e.g., a compound having active hydrogen), such as an alcohol compound or an amine compound, to the following reaction, it is possible to introduce the structure of an alcohol compound, an amine compound, or the like into a resin having a urea bond. Preferred examples of the compound having active hydrogen include those described above for the microgel.

[0416]

[0417] The resin having a urea bond preferably has an ethylenically unsaturated group, and more preferably has a group represented by the following formula (PETA).

[0418]

[0419] In formula (PETA), the wavy line portion represents the bonding position to other structures.

[0420] Furthermore, from the viewpoints of printing durability and on-press developability, the image recording layer preferably contains thermoplastic resin particles. The thermoplastic resin contained in the thermoplastic resin particles is not particularly limited, and examples thereof include polyethylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polymethyl (meth)acrylate, polyethyl (meth)acrylate, polybutyl (meth)acrylate, polyacrylonitrile, polyvinyl acetate, and copolymers thereof. The thermoplastic resin may be in a latex state. The thermoplastic resin according to the present disclosure is preferably a resin that forms part or all of the hydrophobic film that forms the recording layer by melting or softening the thermoplastic resin due to heat generated in the exposure step described below.

[0421] From the viewpoint of ink receptivity and printing durability, the thermoplastic resin preferably contains a resin A having a structural unit formed from an aromatic vinyl compound and a structural unit having a cyano group.

[0422] Resin A contained in the thermoplastic resin preferably has a structural unit formed by an aromatic vinyl compound. Examples of aromatic vinyl compounds include compounds having a structure in which a vinyl group is bonded to an aromatic ring. Examples of aromatic vinyl compounds include styrene compounds and vinylnaphthalene compounds, with styrene being preferred and styrene being more preferred. Examples of styrene compounds include styrene, p-methylstyrene, p-methoxystyrene, β-methylstyrene, p-methyl-β-methylstyrene, α-methylstyrene, and p-methoxy-β-methylstyrene, with styrene being preferred. Examples of vinylnaphthalene compounds include 1-vinylnaphthalene, methyl-1-vinylnaphthalene, β-methyl-1-vinylnaphthalene, 4-methyl-1-vinylnaphthalene, 4-methoxy-1-vinylnaphthalene, with 1-vinylnaphthalene being preferred.

[0423] Furthermore, as a structural unit formed from an aromatic vinyl compound, a structural unit represented by the following formula A1 can be preferably mentioned.

[0424]

[0425] In formula A1, R Ａ１ and R Ａ２ each independently represents a hydrogen atom or an alkyl group, Ar represents an aromatic ring group, R Ａ３ represents a substituent, and n represents an integer of 0 or more and not more than the maximum number of substituents on Ar. Ａ１ and R Ａ２ are each independently preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, more preferably a hydrogen atom or a methyl group, and even more preferably a hydrogen atom. In Formula A1, Ar is preferably a benzene ring or a naphthalene ring, and more preferably a benzene ring. In Formula A1, R Ａ３is preferably an alkyl group or an alkoxy group, more preferably an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, and even more preferably a methyl group or a methoxy group. Ａ３ If there are multiple R Ａ３ In formula A1, n is preferably an integer of 0 to 2, more preferably 0 or 1, and even more preferably 0.

[0426] In Resin A contained in the thermoplastic resin, the content of the structural unit formed by the aromatic vinyl compound is preferably greater than the content of the structural unit having a cyano group, which will be described later, from the viewpoint of ink receptivity, and is more preferably 15% by mass to 85% by mass, and even more preferably 30% by mass to 70% by mass, relative to the total mass of the thermoplastic resin.

[0427] The resin A contained in the thermoplastic resin particles preferably contains a structural unit having a cyano group. The cyano group is usually preferably introduced into the resin A as a structural unit containing a cyano group using a compound (e.g., a monomer) having a cyano group. Examples of the compound having a cyano group include an acrylonitrile compound, and (meth)acrylonitrile is preferred. The structural unit having a cyano group is preferably a structural unit formed by an acrylonitrile compound, and more preferably a structural unit formed by (meth)acrylonitrile.

[0428] Furthermore, preferred examples of the structural unit formed by a compound having a cyano group include a structural unit represented by the following formula B1.

[0429]

[0430] In formula B1, R Ｂ１ represents a hydrogen atom or an alkyl group. Ｂ１ is preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, more preferably a hydrogen atom or a methyl group, and even more preferably a hydrogen atom.

[0431] From the viewpoint of ink receptivity, the content of the structural unit having a cyano group in Resin A is preferably smaller than the content of the structural unit formed from the aromatic vinyl compound, and is more preferably 55% by mass to 90% by mass, and even more preferably 60% by mass to 85% by mass, relative to the total mass of Resin A.

[0432] Furthermore, when resin A contained in the thermoplastic resin contains a structural unit formed from an aromatic vinyl compound and a structural unit having a cyano group, the content ratio of the structural unit formed from the aromatic vinyl compound to the structural unit having a cyano group (i.e., structural unit formed from the aromatic vinyl compound:structural unit having a cyano group) is preferably 5:5 to 9:1, and more preferably 6:4 to 8:2, on a mass basis.

[0433] From the viewpoints of printing durability and chemical resistance, it is preferable that the resin A contained in the thermoplastic resin particles further contains a structural unit formed by an N-vinyl heterocyclic compound. Examples of the N-vinyl heterocyclic compound include N-vinylpyrrolidone, N-vinylcarbazole, N-vinylpyrrole, N-vinylphenothiazine, N-vinylsuccinimide, N-vinylphthalimide, N-vinylcaprolactam, and N-vinylimidazole, with N-vinylpyrrolidone being preferred.

[0434] Furthermore, preferred examples of the structural unit formed by the N-vinyl heterocyclic compound include a structural unit represented by the following formula C1:

[0435]

[0436] In formula C1, Ar Ｎ represents a heterocyclic structure containing a nitrogen atom, and Ar Ｎ The nitrogen atom in the formula C1 is bonded to the carbon atom marked with *. Ｎ The heterocyclic structure represented by the formula (I) is preferably a pyrrolidone ring, a carbazole ring, a pyrrole ring, a phenothiazine ring, a succinimide ring, a phthalimide ring, a caprolactam ring, or an imidazole ring, and more preferably a pyrrolidone ring. Ｎ The heterocyclic structure represented by the formula: may have a known substituent.

[0437] The content of the structural unit formed by the N-vinyl heterocyclic compound in Resin A is preferably 5% by mass to 50% by mass, and more preferably 10% by mass to 40% by mass, relative to the total mass of Resin A.

[0438] The resin A contained in the thermoplastic resin particles may contain a structural unit having an acidic group, but from the viewpoint of on-press developability and ink receptivity, it is preferable that the resin A does not contain a structural unit having an acidic group. Specifically, the content of the structural unit having an acidic group in the thermoplastic resin is preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less. The lower limit of the content is not particularly limited and may be 0% by mass. Furthermore, the acid value of the thermoplastic resin is preferably 160 mg KOH / g or less, more preferably 80 mg KOH / g or less, and even more preferably 40 mg KOH / g or less. The lower limit of the acid value is not particularly limited and may be 0 mg KOH / g. In the present disclosure, the acid value is determined by a measurement method in accordance with JIS K0070:1992.

[0439] From the viewpoint of ink receptivity, the resin A contained in the thermoplastic resin particles may contain a structural unit containing a hydrophobic group. Examples of the hydrophobic group include an alkyl group, an aryl group, and an aralkyl group. The structural unit containing a hydrophobic group is preferably a structural unit formed from an alkyl (meth)acrylate compound, an aryl (meth)acrylate compound, or an aralkyl (meth)acrylate compound, and more preferably a structural unit formed from an alkyl (meth)acrylate compound. The alkyl group in the alkyl (meth)acrylate compound preferably has 1 to 10 carbon atoms. The alkyl group may be linear or branched, or may have a cyclic structure. Examples of the alkyl (meth)acrylate compound include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and dicyclopentanyl (meth)acrylate. The number of carbon atoms in the aryl group in the aryl (meth)acrylate compound is preferably 6 to 20, and more preferably a phenyl group. The aryl group may have a known substituent. A preferred example of the aryl (meth)acrylate compound is phenyl (meth)acrylate. The number of carbon atoms in the alkyl group in the aralkyl (meth)acrylate compound is preferably 1 to 10. The alkyl group may be linear or branched, or may have a cyclic structure. The number of carbon atoms in the aryl group in the aralkyl (meth)acrylate compound is preferably 6 to 20, and more preferably a phenyl group. A preferred example of the aralkyl (meth)acrylate compound is benzyl (meth)acrylate.

[0440] The content of the structural unit having a hydrophobic group in the resin A contained in the thermoplastic resin particles is preferably 5% by mass to 50% by mass, and more preferably 10% by mass to 30% by mass, relative to the total mass of the resin A.

[0441] The thermoplastic resin contained in the thermoplastic resin particles preferably has a hydrophilic group from the viewpoint of printing durability and on-press developability.The hydrophilic group is not particularly limited as long as it has a hydrophilic structure, and examples thereof include an acid group such as a carboxy group, a hydroxy group, an amino group, a cyano group, and a polyalkylene oxide structure.From the viewpoint of printing durability and on-press developability, the hydrophilic group is preferably a group having a polyalkylene oxide structure, a group having a polyester structure, or a sulfonic acid group, more preferably a group having a polyalkylene oxide structure or a sulfonic acid group, and even more preferably a group having a polyalkylene oxide structure.

[0442] From the viewpoint of on-press developability, the polyalkylene oxide structure is preferably a polyethylene oxide structure, a polypropylene oxide structure, or a poly(ethylene oxide / propylene oxide) structure. Furthermore, from the viewpoint of on-press developability, the polyalkylene oxide structure among the hydrophilic groups is preferably a polypropylene oxide structure, and more preferably a polyethylene oxide structure or a polypropylene oxide structure. From the viewpoint of on-press developability, the number of alkylene oxide structures in the polyalkylene oxide structure is preferably 2 or more, more preferably 5 or more, even more preferably 5 to 200, and particularly preferably 8 to 150.

[0443] From the viewpoint of on-press developability, the hydrophilic group is preferably a group represented by the formula Z.

[0444] From the viewpoint of improving printing durability, chemical resistance, and on-press developability, the resin A contained in the thermoplastic resin particles preferably contains a structural unit having a hydrophilic group. Examples of the hydrophilic group include —OH, —CN, —CONR １ R ２ , -NR ２ COR １ (R １ and R ２ R each independently represents a hydrogen atom, an alkyl group, an alkenyl group, or an aryl group. １ and R ２may be bonded to form a ring. ３ R ４ , -N ＋ R ３ R ４ R ５ X － (R ３ ~R ５ each independently represents an alkyl group having 1 to 8 carbon atoms; X － represents a counter anion), a group represented by the following formula PO, and a hydrophilic group preferably contained in the thermoplastic resin contained in the thermoplastic resin particles. １ R ２ or a group represented by the formula PO is preferred, and a group represented by the formula PO is more preferred.

[0445]

[0446] In the formula PO, L Ｐ each independently represents an alkylene group; R Ｐ represents a hydrogen atom or an alkyl group, and n represents an integer of 1 to 100. Ｐ are each independently preferably an ethylene group, a 1-methylethylene group or a 2-methylethylene group, more preferably an ethylene group. Ｐ is preferably a hydrogen atom or an alkyl group having 1 to 18 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, still more preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and particularly preferably a hydrogen atom or a methyl group. In formula PO, n is preferably an integer of 1 to 10, more preferably an integer of 1 to 4.

[0447] The content of the structural unit having a hydrophilic group in the resin A is preferably 5% by mass to 60% by mass, and more preferably 10% by mass to 30% by mass, relative to the total mass of the resin A.

[0448] The resin A contained in the thermoplastic resin particles may further contain other structural units. The other structural units may contain structural units other than the above-mentioned structural units without any particular limitation, and examples thereof include structural units formed by an acrylamide compound, a vinyl ether compound, etc. Examples of acrylamide compounds include (meth)acrylamide, N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, N-propyl(meth)acrylamide, N-butyl(meth)acrylamide, N,N'-dimethyl(meth)acrylamide, N,N'-diethyl(meth)acrylamide, N-hydroxyethyl(meth)acrylamide, N-hydroxypropyl(meth)acrylamide, and N-hydroxybutyl(meth)acrylamide. Examples of vinyl ether compounds include methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, n-butyl vinyl ether, tert-butyl vinyl ether, 2-ethylhexyl vinyl ether, n-nonyl vinyl ether, lauryl vinyl ether, cyclohexyl vinyl ether, cyclohexylmethyl vinyl ether, 4-methylcyclohexylmethyl vinyl ether, benzyl vinyl ether, dicyclopentenyl vinyl ether, 2-dicyclopentenoxyethyl vinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether, butoxyethyl vinyl ether, methoxyethoxyethyl vinyl ether, ethoxyethoxyethyl vinyl ether, methoxypolyethylene glycol vinyl ether, tetrahydrofurfuryl vinyl ether, 2-hydroxyethyl vinyl ether, 2-hydroxypropyl vinyl ether, 4-hydroxybutyl vinyl ether, 4-hydroxymethylcyclohexylmethyl vinyl ether, diethylene glycol monovinyl ether, polyethylene glycol vinyl ether, chloroethyl vinyl ether, chlorobutyl vinyl ether, chloroethoxyethyl vinyl ether, phenylethyl vinyl ether, and phenoxypolyethylene glycol vinyl ether.

[0449] The content of other structural units in the thermoplastic resin is preferably 5% by mass to 50% by mass, and more preferably 10% by mass to 30% by mass, relative to the total mass of the thermoplastic resin.

[0450] From the viewpoints of printing durability and ink receptivity, the glass transition temperature (Tg) of the thermoplastic resin is preferably 60° C. to 150° C., more preferably 80° C. to 140° C., and even more preferably 90° C. to 130° C. When the thermoplastic resin particles contain two or more thermoplastic resins, the value determined by the FOX equation described below is referred to as the glass transition temperature of the thermoplastic resin.

[0451] In the present disclosure, the glass transition temperature of a resin can be measured using differential scanning calorimetry (DSC). A specific measurement method is performed in accordance with the method described in JIS K 7121 (1987) or JIS K 6240 (2011). The glass transition temperature used herein is the extrapolated glass transition onset temperature (hereinafter sometimes referred to as Tig). The method for measuring the glass transition temperature will be described in more detail below. To determine the glass transition temperature, the resin is held at a temperature approximately 50°C lower than the expected Tg of the resin until the apparatus stabilizes, and then heated at a heating rate of 20°C / min to a temperature approximately 30°C higher than the temperature at which the glass transition ends, and a differential thermal analysis (DTA) curve or a DSC curve is created. The extrapolated glass transition onset temperature (Tig), i.e., the glass transition temperature Tg in this specification, is determined as the temperature at the intersection of a straight line extending the low-temperature baseline of a DTA curve or a DSC curve toward a higher temperature and a tangent drawn at the point where the gradient of the curve in the stepwise change portion of the glass transition is maximum.

[0452] When the thermoplastic resin particles contain two or more thermoplastic resins, the Tg of the thermoplastic resin contained in the thermoplastic resin particles can be calculated as follows: When the Tg of the first thermoplastic resin is Tg1(K), the mass fraction of the first thermoplastic resin relative to the total mass of the thermoplastic resin components in the thermoplastic resin particles is W1, the Tg of the second thermoplastic resin is Tg2(K), and the mass fraction of the second resin relative to the total mass of the thermoplastic resin components in the thermoplastic resin particles is W2, the Tg0(K) of the thermoplastic resin particles can be estimated according to the following FOX formula: FOX formula: 1 / Tg0=(W1 / Tg1)+(W2 / Tg2) Furthermore, when the thermoplastic resin particles contain three types of resins, or when three types of thermoplastic resin particles containing different types of thermoplastic resins are contained in the pretreatment liquid, the Tg of the thermoplastic resin particles can be estimated according to the following formula, similar to the above, when the Tg of the nth resin is Tgn(K) and the mass fraction of the nth resin relative to the total mass of the resin components in the thermoplastic resin particles is Wn. FOX formula: 1 / Tg0=(W1 / Tg1)+(W2 / Tg2)+(W3 / Tg3)...+(Wn / Tgn)

[0453] In the present disclosure, Tg is a value measured by a differential scanning calorimetry (DSC). As the differential scanning calorimeter (DSC), for example, an EXSTAR6220 manufactured by SII NanoTechnology, Inc. can be used.

[0454] From the viewpoint of printing durability, the arithmetic mean particle size of the thermoplastic resin particles is preferably 1 nm or more and 200 nm or less, more preferably 3 nm or more and less than 80 nm, and even more preferably 10 nm or more and 49 nm or less.

[0455] The arithmetic mean particle size of thermoplastic resin particles in the present disclosure refers to a value measured by dynamic light scattering (DLS) unless otherwise specified. The arithmetic mean particle size of thermoplastic resin particles by DLS is measured using a Brookhaven BI-90 (manufactured by Brookhaven Instrument Company) according to the manual for the instrument.

[0456] The weight average molecular weight of the thermoplastic resin contained in the thermoplastic resin particles is preferably 3,000 to 300,000, and more preferably 5,000 to 100,000.

[0457] The thermoplastic resin contained in the thermoplastic resin particles can be produced by any known method, without any particular limitation. For example, the thermoplastic resin can be obtained by polymerizing, by a known method, a styrene compound, an acrylonitrile compound, and, if necessary, at least one compound selected from the group consisting of the N-vinyl heterocyclic compound, the compound used to form the structural unit having an ethylenically unsaturated group, the compound used to form the structural unit having an acidic group, the compound used to form the structural unit having a hydrophobic group, and the compound used to form the other structural unit.

[0458] Specific examples of the thermoplastic resin contained in the thermoplastic resin particles are shown in the table below, but the thermoplastic resin used in the present disclosure is not limited to these.

[0459]

[0460]

[0461]

[0462] In the above specific examples, the content ratio of each structural unit can be appropriately changed in accordance with the preferred range of the content of each structural unit described above. In addition, the weight average molecular weight of each compound shown in the above specific examples can be appropriately changed in accordance with the preferred range of the weight average molecular weight of the thermoplastic resin described above.

[0463] The average particle size of the particles is preferably 0.01 μm to 3.0 μm, more preferably 0.03 μm to 2.0 μm, and even more preferably 0.10 μm to 1.0 μm. Within this range, good resolution and stability over time can be obtained. The average primary particle size of the particles in this disclosure is measured by a light scattering method, or by taking an electron microscope photograph of the particles, measuring the particle sizes of a total of 5,000 particles on the photograph, and calculating the average value. For non-spherical particles, the particle size is taken to be the particle size of a spherical particle having the same particle area as the particle area on the photograph. Furthermore, the average particle size in this disclosure is taken to be the volume-average particle size, unless otherwise specified.

[0464] The image recording layer may contain one type of particle, particularly polymer particles, or two or more types. From the viewpoints of on-press developability and printing durability, the content of the particles, particularly polymer particles, in the image recording layer is preferably 5% to 90% by mass, more preferably 10% to 90% by mass, even more preferably 20% to 90% by mass, and particularly preferably 50% to 90% by mass, relative to the total mass of the image recording layer. From the viewpoints of on-press developability and printing durability, the content of the polymer particles in the image recording layer is preferably 20% to 100% by mass, more preferably 35% to 100% by mass, even more preferably 50% to 100% by mass, and particularly preferably 80% to 100% by mass, relative to the total mass of components of the image recording layer having a molecular weight of 3,000 or more.

[0465] <Binder polymer> The image recording layer may contain a binder polymer. As the binder polymer, a binder polymer used in the image recording layer of an on-press development type lithographic printing plate precursor can be used. Specifically, as the binder polymer, the binder polymers described in paragraphs 0288 to 0317 of WO 2022 / 019217 can be suitably used.

[0466] In the image recording layer, one type of binder polymer may be used alone, or two or more types may be used in combination. The binder polymer may be contained in the image recording layer in any amount, but the content of the binder polymer is preferably 1% by mass to 90% by mass, and more preferably 5% by mass to 80% by mass, relative to the total mass of the image recording layer. Furthermore, when the image recording layer of the present disclosure contains another binder polymer, the content of the other binder polymer relative to the total mass of the thermoplastic resin particles and the other binder polymer is preferably more than 0% by mass and 99% by mass or less, more preferably 20% by mass to 95% by mass, and even more preferably 40% by mass to 90% by mass.

[0467] <Oil Agent> The image recording layer preferably contains an oil agent. In the present disclosure, the oil agent refers to a hydrophobic compound that is liquid at 80°C and separates when mixed with an equal mass of water without being miscible. When two or more oil agents are used, even if a compound with a melting point of 80°C or higher is included, it is sufficient that the two or more oil agents are in a liquid state at 80°C when mixed. Furthermore, from the viewpoints of on-press developability and suppression of turbidity of the fountain solution, the oil agent is preferably a compound with a molecular weight of less than 1,000, more preferably a compound with a molecular weight of 200 to 800, and particularly preferably a compound with a molecular weight of 300 to 500. Furthermore, from the viewpoints of on-press developability and suppression of turbidity of the fountain solution, the oil agent is preferably a compound with a boiling point at 1 atmosphere of 200°C or higher, more preferably a compound with a boiling point at 1 atmosphere of 250°C or higher, even more preferably a compound with a boiling point at 1 atmosphere of 300°C or higher, and particularly preferably a compound with a boiling point at 1 atmosphere of 400°C or higher and 500°C or lower. In the present disclosure, unless otherwise specified, the term "boiling point" refers to the boiling point at 1 atmosphere. From the viewpoints of on-press developability and suppression of turbidity in the dampening water, the melting point of the oil agent at 1 atmosphere is preferably 50°C or lower, more preferably 30°C or lower, and particularly preferably -200°C or higher and 25°C or lower. In the present disclosure, unless otherwise specified, the term "melting point" refers to the melting point at 1 atmosphere.

[0468] Examples of oil agents include phosphate ester compounds, aromatic hydrocarbon compounds, glyceride compounds, fatty acid compounds, aromatic ester compounds, etc. Among these, from the viewpoints of printing durability, ink receptivity, on-press developability, and suppression of turbidity in the dampening water, at least one compound selected from the group consisting of phosphate ester compounds, aromatic hydrocarbon compounds, glyceride compounds, and aromatic ester compounds is preferred, at least one compound selected from the group consisting of phosphate ester compounds, aromatic hydrocarbon compounds, and glyceride compounds is more preferred, at least one compound selected from the group consisting of phosphate ester compounds and aromatic hydrocarbon compounds is even more preferred, and a phosphate ester compound is particularly preferred.

[0469] As the phosphate ester compound, from the viewpoints of printing durability, ink receptivity, on-press developability, and suppression of fountain solution clouding, a phosphate triester compound is preferred, a triaryl phosphate ester compound is more preferred, tricresyl phosphate is even more preferred, and a mixture of two or more of the ortho-, meta-, and para-tricresyl phosphate isomers is particularly preferred. As the aromatic hydrocarbon compound, from the viewpoints of on-press developability and suppression of fountain solution clouding, a compound having two or more aromatic rings is preferred, and a compound having two or more non-fused benzene rings is more preferred. As the glyceride compound, from the viewpoints of on-press developability and suppression of fountain solution clouding, a triglyceride compound is preferred, a fatty oil is more preferred, and a fatty oil that is liquid at 25°C, such as castor oil, is particularly preferred. As the fatty acid compound, from the viewpoints of on-press developability and suppression of fountain solution clouding, an unsaturated fatty acid is preferred, an unsaturated fatty acid having 8 to 30 carbon atoms is more preferred, and an unsaturated fatty acid having 12 to 24 carbon atoms is particularly preferred. As the aromatic ester compound, from the viewpoints of on-press developability and suppression of turbidity of the fountain solution, an aromatic diester compound is preferred, and an aromatic diester compound having an aliphatic ring is more preferred. As the aliphatic ester compound, from the viewpoints of on-press developability and suppression of turbidity of the fountain solution, an aliphatic ester compound having a branched alkyl group is preferred, and an aliphatic ester compound having a branched alkyl group and having 10 to 24 carbon atoms is more preferred.

[0470] From the viewpoints of printing durability, ink receptivity, on-press developability, and dampening water turbidity suppression, the oil agent preferably contains an oil agent having a phosphorus atom, and more preferably an oil agent having a phosphorus atom. Also, from the viewpoints of on-press developability and dampening water turbidity suppression, the oil agent preferably contains an oil agent having an aromatic ring, more preferably contains an oil agent having two or more aromatic rings, and particularly preferably contains an oil agent having two or more non-condensed benzene rings.

[0471] From the viewpoints of printing durability, ink receptivity, on-press developability, and dampening water turbidity suppression, the clogP value of the oil agent is preferably 5.0 or more, more preferably 5.50 or more, even more preferably 5.50 or more and 10.0 or less, and particularly preferably 5.60 or more and 7.00 or less. The clogP value is a value obtained by calculating the common logarithm logP of the partition coefficient P between 1-octanol and water. Known methods and software can be used to calculate the clogP value, but unless otherwise specified, the present disclosure will use the ClogP program incorporated into Cambridgesoft's ChemBioDraw Ultra 12.0.

[0472] Specific examples of oil agents include tricresyl phosphate, dimethyl(1-phenylethyl)benzene, 2,4-diphenyl-4-methyl-1-pentene, dicyclohexyl phthalate, castor oil, α-linolenic acid, and tri(2-ethylhexyl) phosphate.

[0473] Although only one oil agent may be used or two or more oil agents may be used in combination, from the viewpoints of on-press developability and suppression of turbidity of the dampening water, it is preferable that the image recording layer contains two or more oil agents having different structures. The content of the oil agent is preferably 0.0001% by mass to 10.0% by mass, more preferably 0.0002% by mass to 1.0% by mass, still more preferably 0.0005% by mass to 0.5% by mass, and particularly preferably 0.001% by mass to 0.05% by mass, relative to the total mass of the image recording layer.

[0474] <Chain Transfer Agent> The image recording layer may contain a chain transfer agent. As the chain transfer agent, a chain transfer agent used in the image recording layer of an on-press development type lithographic printing plate precursor can be used. Specifically, as the chain transfer agent, the chain transfer agents described in paragraphs 0388 to 0393 of WO 2022 / 019217 can be suitably used.

[0475] The content of the chain transfer agent is preferably 0.01% by mass to 50% by mass, more preferably 0.05% by mass to 40% by mass, and even more preferably 0.1% by mass to 30% by mass, based on the total mass of the image recording layer.

[0476] <Oil-sensitizing agent> The image recording layer may contain an oil-sensitizing agent to improve ink receptivity. As the oil-sensitizing agent, an oil-sensitizing agent used in the image recording layer of an on-press development type lithographic printing plate precursor can be used. Specifically, as the oil-sensitizing agent, the oil-sensitizing agents described in paragraphs 0395 to 0404 of WO 2022 / 019217 can be suitably used.

[0477] The content of the oil sensitizer is preferably from 1 to 40.0% by mass, more preferably from 2 to 25.0% by mass, and even more preferably from 3 to 20.0% by mass, based on the total mass of the image recording layer.

[0478] The image recording layer may contain one oil-sensitizing agent alone, or two or more may be used in combination. One preferred embodiment of the image recording layer used in the present disclosure is an embodiment containing two or more compounds as the oil-sensitizing agent. Specifically, from the viewpoint of achieving both on-press developability and ink-receptivity, the image recording layer used in the present disclosure preferably uses a phosphonium compound, a nitrogen-containing low-molecular-weight compound, and an ammonium group-containing polymer in combination as the oil-sensitizing agent, and more preferably uses a phosphonium compound, a quaternary ammonium salt, and an ammonium group-containing polymer in combination.

[0479] <Development Accelerator> The image recording layer preferably further contains a development accelerator, the polarity term of which SP value is preferably from 6.0 to 26.0, more preferably from 6.2 to 24.0, still more preferably from 6.3 to 23.5, and particularly preferably from 6.4 to 22.0.

[0480] The SP value (solubility parameter, unit: (cal / cm ３ ) １／２The value of the polar term in the Hansen solubility parameter is the value of the polar term δp in the Hansen solubility parameter. The Hansen solubility parameter is a solubility parameter introduced by Hildebrand, which is divided into three components: a dispersion term δd, a polar term δp, and a hydrogen bonding term δh, and is expressed in a three-dimensional space. In this disclosure, the polar term δp is used. δp [cal / cm ３ ] is the Hansen solubility parameter dipole-dipole term, V [cal / cm ３ ] is the molar volume, μ[D] is the dipole moment. For δp, the following formula simplified by Hansen and Beerbower is generally used:

[0481]

[0482] The development accelerator is preferably a hydrophilic polymer compound or a hydrophilic low-molecular-weight compound. In the present disclosure, "hydrophilic" refers to a polarity term of the SP value of 6.0 to 26.0, a hydrophilic polymer compound refers to a compound having a molecular weight (weight-average molecular weight when the molecular weight is distributed) of 3,000 or more, and a hydrophilic low-molecular-weight compound refers to a compound having a molecular weight (weight-average molecular weight when the molecular weight is distributed) of less than 3,000.

[0483] Examples of hydrophilic polymer compounds include cellulose compounds, with cellulose compounds being preferred. Examples of cellulose compounds include cellulose or compounds in which at least a portion of cellulose has been modified (i.e., modified cellulose compounds), with modified cellulose compounds being preferred. Preferred modified cellulose compounds include compounds in which at least a portion of the hydroxy groups of cellulose have been substituted with at least one group selected from the group consisting of alkyl groups and hydroxyalkyl groups. The degree of substitution of the compound in which at least a portion of the hydroxy groups of cellulose have been substituted with at least one group selected from the group consisting of alkyl groups and hydroxyalkyl groups is preferably 0.1 to 6.0, more preferably 1 to 4. Preferred modified cellulose compounds are alkyl cellulose compounds or hydroxyalkyl cellulose compounds, with hydroxyalkyl cellulose compounds being more preferred. Preferred alkyl cellulose compounds are methyl cellulose. Preferred hydroxyalkyl cellulose compounds are hydroxypropyl cellulose.

[0484] The molecular weight of the hydrophilic polymer compound (however, when the molecular weight distribution is present, the weight average molecular weight) is preferably 3,000 to 5,000,000, and more preferably 5,000 to 200,000.

[0485] Examples of the hydrophilic low-molecular-weight compound include glycol compounds, polyol compounds, organic amine compounds, organic sulfonic acid compounds, organic sulfamine compounds, organic sulfuric acid compounds, organic phosphonic acid compounds, organic carboxylic acid compounds, and betaine compounds, with polyol compounds, organic sulfonic acid compounds, and betaine compounds being preferred.

[0486] Examples of glycol compounds include glycols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, and tripropylene glycol, as well as ether or ester derivatives of these compounds. Examples of polyol compounds include glycerin, pentaerythritol, and tris(2-hydroxyethyl)isocyanurate. Examples of organic amine compounds include triethanolamine, diethanolamine, monoethanolamine, and salts thereof. Examples of organic sulfonic acid compounds include alkyl sulfonic acid, toluene sulfonic acid, benzene sulfonic acid, and salts thereof, with alkyl sulfonic acids having an alkyl group of 1 to 10 carbon atoms being preferred. Examples of organic sulfamine compounds include alkyl sulfamic acid and salts thereof. Examples of organic sulfate compounds include alkyl sulfates, alkyl ether sulfates, and salts thereof. Examples of organic phosphonic acid compounds include phenylphosphonic acid and salts thereof. Examples of organic carboxylic acid compounds include tartaric acid, oxalic acid, citric acid, malic acid, lactic acid, gluconic acid, and salts thereof. Examples of the betaine compound include a phosphobetaine compound, a sulfobetaine compound, and a carboxybetaine compound, and a preferred example is trimethylglycine.

[0487] The molecular weight of the hydrophilic low-molecular-weight compound (however, if it has a molecular weight distribution, the weight-average molecular weight) is preferably 100 or more and less than 3,000, and more preferably 300 to 2,500.

[0488] The development accelerator is preferably a compound having a cyclic structure. The cyclic structure is not particularly limited, but examples include a glucose ring, an isocyanuric ring, an aromatic ring which may have a heteroatom, and an aliphatic ring which may have a heteroatom, each of which may have at least a portion of a hydroxy group substituted. A glucose ring or an isocyanuric ring is preferred. Examples of compounds having a glucose ring include the above-mentioned cellulose compounds. Examples of compounds having an isocyanuric ring include the above-mentioned tris(2-hydroxyethyl)isocyanurate. Examples of compounds having an aromatic ring include the above-mentioned toluenesulfonic acid and benzenesulfonic acid. Examples of compounds having an aliphatic ring include the above-mentioned alkyl sulfates in which the alkyl group has a cyclic structure.

[0489] The compound having a cyclic structure preferably has a hydroxy group. Preferred examples of the compound having a hydroxy group and a cyclic structure include the above-mentioned cellulose compound and tris(2-hydroxyethyl)isocyanurate.

[0490] The development accelerator is preferably an onium salt compound. Examples of the onium salt compound include ammonium compounds and sulfonium compounds, with ammonium compounds being preferred. Examples of the development accelerator that is an onium salt compound include trimethylglycine. The onium salt compound in the electron-accepting polymerization initiator is a compound whose polarity term of the SP value is not 6.0 to 26.0, and is therefore not included in the development accelerator.

[0491] The image recording layer may contain one type of development accelerator alone, or two or more types may be used in combination. In the present disclosure, one preferred embodiment of the image recording layer is an embodiment in which the image recording layer contains two or more compounds as development accelerators. Specifically, from the viewpoint of on-press developability and ink receptivity, the image recording layer preferably contains the polyol compound and the betaine compound, the betaine compound and the organic sulfonic acid compound, or the polyol compound and the organic sulfonic acid compound as development accelerators.

[0492] The content of the development accelerator relative to the total mass of the image recording layer is preferably from 0.1 to 20% by mass, more preferably from 0.5 to 15% by mass, and even more preferably from 1 to 10% by mass.

[0493] <Surfactant> The image recording layer preferably contains a surfactant from the viewpoints of promoting on-press developability, improving the coating surface, etc. Examples of the surfactant include nonionic surfactants, anionic surfactants, cationic surfactants, amphoteric surfactants, and fluorine-based surfactants. The surfactants may be used alone or in combination of two or more.

[0494] The nonionic surfactant used in the present disclosure is not particularly limited, and conventionally known surfactants can be used. Examples include polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene polystyrylphenyl ethers, polyoxyethylene polyoxypropylene alkyl ethers, glycerin fatty acid partial esters, sorbitan fatty acid partial esters, pentaerythritol fatty acid partial esters, propylene glycol mono-fatty acid esters, sucrose fatty acid partial esters, polyoxyethylene sorbitan fatty acid partial esters, polyoxyethylene sorbitol fatty acid partial esters, polyethylene glycol fatty acid esters, polyglycerin fatty acid partial esters, polyoxyethylated castor oils, polyoxyethylene glycerin fatty acid partial esters, fatty acid diethanolamides, N,N-bis-2-hydroxyalkylamines, polyoxyethylene alkylamines, triethanolamine fatty acid esters, trialkylamine oxide, polyethylene glycol, and copolymers of polyethylene glycol and polypropylene glycol.

[0495] The anionic surfactant used in the present disclosure is not particularly limited, and conventionally known surfactants can be used. For example, fatty acid salts, abietic acid salts, hydroxyalkanesulfonates, alkanesulfonates, dialkylsulfosuccinate salts, linear alkylbenzenesulfonates, branched alkylbenzenesulfonates, alkylnaphthalenesulfonates, alkylphenoxypolyoxyethylenepropylsulfonates, polyoxyethylene alkylsulfophenyl ether salts, N-methyl-N-oleyl taurine sodium salt, N-alkylsulfosuccinic acid monoamide disodium salt, petroleum sulfonates, sulfated beef tallow oil, sulfate ester salts of fatty acid alkyl esters, alkane sulf ... dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkylsulfosuccinate salts, dialkyl Examples of such esters include alkyl sulfate salts, polyoxyethylene alkyl ether sulfate salts, fatty acid monoglyceride sulfate salts, polyoxyethylene alkylphenyl ether sulfate salts, polyoxyethylene styrylphenyl ether sulfate salts, alkyl phosphate salts, polyoxyethylene alkyl ether phosphate salts, polyoxyethylene alkylphenyl ether phosphate salts, partially saponified products of styrene / maleic anhydride copolymers, partially saponified products of olefin / maleic anhydride copolymers, and naphthalenesulfonate formalin condensates.

[0496] The cationic surfactant used in the present disclosure is not particularly limited, and conventionally known surfactants can be used. Examples include alkylamine salts, quaternary ammonium salts, polyoxyethylene alkylamine salts, and polyethylene polyamine derivatives. The amphoteric surfactant used in the present disclosure is not particularly limited, and conventionally known surfactants can be used. Examples include carboxybetaines, aminocarboxylic acids, sulfobetaines, aminosulfuric acid esters, and imitazolines.

[0497] Among the surfactants listed above, "polyoxyethylene" can also be read as "polyoxyalkylene" such as polyoxymethylene, polyoxypropylene, and polyoxybutylene, and these surfactants can also be used in the present disclosure.

[0498] More preferred surfactants include fluorine-based surfactants containing a perfluoroalkyl group in the molecule. Examples of such fluorine-based surfactants include anionic types such as perfluoroalkyl carboxylates, perfluoroalkyl sulfonates, and perfluoroalkyl phosphates; amphoteric types such as perfluoroalkyl betaines; cationic types such as perfluoroalkyl trimethyl ammonium salts; and nonionic types such as perfluoroalkyl amine oxides, perfluoroalkyl ethylene oxide adducts, oligomers containing perfluoroalkyl groups and hydrophilic groups, oligomers containing perfluoroalkyl groups and lipophilic groups, oligomers containing perfluoroalkyl groups, hydrophilic groups, and lipophilic groups, and urethanes containing perfluoroalkyl groups and lipophilic groups. Also suitable are the fluorine-based surfactants described in JP-A-62-170950, JP-A-62-226143, and JP-A-60-168144.

[0499] In addition to the surfactants described above, other surfactants may be added, within a range that does not impair the effects of the present disclosure, in order to broaden the stability of processing under the development conditions of the present disclosure or to improve coatability, such as amphoteric surfactants as described in JP-A-59-121044 and JP-A-4-13149; siloxane-based compounds as described in EP 950517; fluorine-containing monomer copolymers as described in JP-A-11-288093; and fluorine-based surfactants as described in JP-A-62-170950.

[0500] Specific examples of amphoteric surfactants include alkyldi(aminoethyl)glycine, alkylpolyaminoethylglycine hydrochloride, 2-alkyl-N-carboxyethyl-N-hydroxyethylimidazolinium betaine, and N-tetradecyl-N,N-betaine type (for example, trade name "Amogene K" manufactured by Daiichi Kogyo Co., Ltd.). Preferred siloxane compounds are block copolymers of dimethylsiloxane and polyalkylene oxide, and specific examples include polyalkylene oxide-modified silicones such as DBE-224, DBE-621, DBE-712, DBP-732, and DBP-534 manufactured by Chisso Corporation, and Tego Glide 100 manufactured by Tego GmbH, Germany.

[0501] Specific examples of commercially available surfactants include the following. Note that "DOWSIL", "XIAMETER", and "SYLGARD" are registered trademarks. In the following, the fact that "DOWSIL", "XIAMETER", and "SYLGARD" are registered trademarks will be omitted.

[0502] In the products manufactured by Dow Corning Toray Co., Ltd., examples include DOWSIL BY 16-205, DOWSIL BY 16-849 Fluid, DOWSIL FZ-3710 Fluid, DOWSIL FZ-3760, DOWSIL FZ-3785, DOWSIL SF 8417 Fluid, DOWSIL BY 16-891, DOWSIL FZ-3789, DOWSIL BY 16-839 Fluid, DOWSIL SF 8411 Fluid, DOWSIL SF 8413 Fluid, DOWSIL SF 8421 Fluid, DOWSIL BY 16-880 Fluid, DOWSIL BY 16-201, DOWSIL SF 8427 Fluid, DOWSIL SF 8428 Fluid, DOWSIL 580 WAX, DOWSIL BY 16-606, DOWSIL BY 16-846 Fluid, XIAMETER OFX-0203 Fluid, XIAMETER OFX-0230 Fluid, DOWSIL SF 8416 Fluid, DOWSIL SF 8419 Fluid, DOWSIL 501W Additive, DOWSIL FZ-2110, DOWSIL FZ-2123, DOWSIL L-7001, SYLGARD OFX-0309 Fluid, XIAMETER OFX-5211 Fluid, DOWSIL SF 8410 Fluid, DOWSIL SH 3746 Fluid, DOWSIL SH 8400 Fluid, DOWSIL SH 8700 Fluid, DOWSIL SH 510 Fluid (100 cSt, 500 cSt), DOWSIL SH 550 Fluid, DOWSIL SH 710 Fluid, DOWSIL FS 1265 Fluid, etc.

[0503] Shin-Etsu Silicone (registered trademark) products from Shin-Etsu Chemical Co., Ltd. include the KP series: KP-124, KP-109, KP-110, KP-121, KP-118, KP-341, KP-112, KP-125, KP-101, KP-106, KP-120, KP-105, KP-104, KP-611, KP-626, KP-327, KP-323, KP-322, KP-625, KP-623, KP-624, KP-620, and KP-651 KF series such as KP-652, KP-650, KP-310, KP-306, KP-301, KP-621, KP-369, KP-368, KP-126, etc., and FL series such as KF-868, KF-865, KF-864, KF-859, KF-393, KF-860, KF-880, KF-8004, KF-8002, KF-8005, KF-867, KF-8021, KF-869, KF -861, KF-877, KF-101, KF-1001, KF-102, KF-1002, KF-1005, KF-2001, KF-2004, KF-99, KF-9901, PAM-E, KF-8 010, KF-8012, KF-8008, KF-105, KF-6000, KF-6001, KF-6002, KF-6003, KF-6123, KF-9701, KF-2012, KF-857, KF-862, KF-858, KF-351A, KF-352A, KF-353, KF-354L, KF-355A, KF-615A, KF-945, KF-640, KF-642, KF-643, K F-644, KF-6020, KF-6204, KF-6011, KF-6012, KF-6015, KF-6017, KF-410, FL-5, FL-100-100cs, FL-100-450c Examples of such polyolefin polymers include FL-100-1,000cs, FL-100-10,000cs, KF-412, KF-413, KF-414, KF-415, KF-4003, KF-4701, KF-4917, KF-7235B, KF-3935, KF-50-100cs, KF-50-300cs, KF-50-1,000cs, KF-50-3,000cs, KF-53, KF-54, and KF-6004.

[0504] BYK products include BYK-300, BYK-302, BYK-306, BYK-307, BYK-310, BYK-313, BYK-315 N, BYK-320, BYK-322, BYK-323, and BYK-325. N, BYK-326*, BYK-327*, BYK-330, BYK-331, BYK-333, BYK-342, BYK-345 / 346, BYK-347, BYK-348, BYK-349 , BYK-370, BYK-375, BYK-377, BYK-378, BYK-3450*, BYK-3451*, BYK-3455, BYK-3456*, BYK-3760*, BYK-UV 3500, BYK-UV 3505*, BYK-UV 3510, BYK-UV 3530, BYK-UV 3535*, BYK-UV 3570, BYK-UV 3575*, BYK-UV 3576, BYK-350, BYK-354, BYK-355 / 356 Acrylic Copolymer, BYK-358 N / 361 N, BYK-381 Acrylic Copolymer, BYK-392 Acrylic Copolymer, BYK-394 Acrylic Copolymer, BYK-3441 Acrylic Copolymer, BYK-399, BYK-3440*, BYK-3550, BYK-3560*, BYK-3565*, BYK-3566*, BYK-SILCLEAN 3700, BYK-SILCLEAN 3701*, BYK-SILCLEAN 3720, BYK-DYNWET 800 N, etc.

[0505] <Other Components> The image recording layer may contain other components such as a polymerization inhibitor, a higher fatty acid derivative, a plasticizer, inorganic particles, an inorganic layer compound, etc. For specific details, see paragraphs 0121 to 0159 of JP-A-2008-284817.

[0506] <<Formation of Image Recording Layer>> The image recording layer in the lithographic printing plate precursor according to the present disclosure can be formed by dispersing or dissolving the necessary components described above in a known solvent to prepare a coating liquid, applying the coating liquid to a support by a known method such as bar coater coating, and drying, as described in paragraphs

[0142] and

[0143] of JP-A No. 2008-195018. The coating amount (solid content) of the image recording layer after coating and drying varies depending on the application, but is generally 0.3 g / m ２ ~3.0g / m ２ Within this range, good sensitivity and good film properties of the image recording layer can be obtained. As the solvent, known solvents can be used. Specific examples include water, acetone, methyl ethyl ketone (2-butanone), cyclohexane, ethyl acetate, ethylene dichloride, tetrahydrofuran, toluene, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, acetylacetone, cyclohexanone, diacetone alcohol, ethylene glycol monomethyl ether acetate, ethylene glycol ethyl ether acetate, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether acetate, 1-methoxy-2-propanol, 3-methoxy-1-propanol, methoxymethoxyethanol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, 3-methoxypropyl acetate, N,N-dimethylformamide, dimethyl sulfoxide, γ-butyrolactone, methyl lactate, and ethyl lactate. The solvent may be used alone or in combination of two or more. The solid content concentration in the coating solution is preferably 1% by mass to 50% by mass. The coating amount (solid content) of the image recording layer after coating and drying varies depending on the application, but is preferably 0.3 g / m from the viewpoint of obtaining good sensitivity and good film properties of the image recording layer. ２ ~3.0g / m２ Preferably, the thickness of the image recording layer in the lithographic printing plate precursor according to the present disclosure is 0.1 μm to 3.0 μm, and more preferably 0.3 μm to 2.0 μm. In the present disclosure, the thickness of each layer in the lithographic printing plate precursor is confirmed by preparing a slice cut in a direction perpendicular to the surface of the lithographic printing plate precursor and observing the cross section of the slice with a scanning electron microscope (SEM).

[0507] (Support) The lithographic printing plate precursor according to the present disclosure has a support. The support can be appropriately selected from known supports for lithographic printing plate precursors. The support is preferably a support having a hydrophilic surface.

[0508] The support in the present disclosure is preferably an aluminum plate that has been subjected to a surface roughening treatment and anodization treatment by a known method. That is, the support in the present disclosure preferably comprises an aluminum plate and an anodized aluminum coating disposed on the aluminum plate.

[0509] Preferably, the support has an aluminum plate and an anodized aluminum film disposed on the aluminum plate, the anodized film being located closer to the image recording layer than the aluminum plate, the anodized film having micropores extending in the depth direction from the surface facing the image recording layer, the micropores having an average diameter of more than 10 nm and not more than 100 nm at the surface of the anodized film. Furthermore, the micropores are composed of large-diameter pores extending from the surface of the anodized film to a depth of 10 nm to 1,000 nm and small-diameter pores communicating with the bottoms of the large-diameter pores and extending from the communicating positions to a depth of 20 nm to 2,000 nm, the large-diameter pores having an average diameter of 15 nm to 100 nm at the surface of the anodized film, and the small-diameter pores having an average diameter of 13 nm or less at the communicating positions.

[0510] 1 is a schematic cross-sectional view of one embodiment of an aluminum support 12a. The aluminum support 12a has a laminated structure in which an aluminum plate 18 and an aluminum anodized coating 20a (hereinafter simply referred to as "anodized coating 20a") are laminated in this order. The anodized coating 20a in the aluminum support 12a is located closer to the image recording layer than the aluminum plate 18. In other words, the lithographic printing plate precursor according to the present disclosure preferably has at least an anodized coating, an image recording layer, and a water-soluble resin layer, in this order, on an aluminum plate.

[0511] - Anodized film - A preferred embodiment of the anodized film 20a will be described below. The anodized film 20a is a film formed on the surface of the aluminum plate 18 by anodizing treatment, and this film has extremely fine micropores 22a that are approximately perpendicular to the film surface and are distributed approximately uniformly. The micropores 22a extend from the surface of the anodized film 20a on the image recording layer side (i.e., the surface of the anodized film 20a on the side opposite the aluminum plate 18) along the thickness direction (i.e., toward the aluminum plate 18).

[0512] The average diameter (i.e., average opening diameter) of the micropores 22a in the anodized coating 20a at the surface of the anodized coating is preferably greater than 10 nm and less than or equal to 100 nm. In terms of the balance between printing durability, stain resistance, and image visibility, a diameter of 15 nm to 60 nm is more preferable, 20 nm to 50 nm is even more preferable, and 25 nm to 40 nm is particularly preferable. The diameter inside the pores may be wider or narrower than that at the surface. When the average diameter exceeds 10 nm, printing durability and image visibility are excellent. Furthermore, when the average diameter is 100 nm or less, printing durability is excellent. The average diameter of the micropores 22a is determined by observing the surface of the anodized coating 20a (N = 4) using a field emission scanning electron microscope (FE-SEM) at a magnification of 150,000 times, and measuring the diameters (here, diameters) of micropores present within a 400 nm × 600 nm range at 50 locations in the four obtained images, and averaging the measured values. When the shape of the micropores 22a is not circular, the equivalent circle diameter is used. The "equivalent circle diameter" is the diameter of a circle when the shape of the opening is assumed to be a circle having the same projected area as the projected area of ​​the opening.

[0513] The shape of the micropores 22a is not particularly limited, and although they are generally straight (i.e., generally cylindrical) in Fig. 1, they may also be conical with a diameter that decreases in the depth direction (thickness direction). The shape of the bottom of the micropores 22a is not particularly limited, and may be curved (convex) or flat.

[0514] In the support, the micropores may be composed of large-diameter pores extending from the surface of the anodized coating to a certain depth and small-diameter pores that communicate with the bottoms of the large-diameter pores and extend from the communication positions to a certain depth. For example, as shown in Figure 2, an aluminum support 12b may include an aluminum plate 18 and an anodized coating 20b having micropores 22b each composed of large-diameter pores 24 and small-diameter pores 26. For example, the micropores 22b in the anodized coating 20b are composed of large-diameter pores 24 extending from the surface of the anodized coating to a depth of 10 nm to 1,000 nm (depth D: see Figure 2), and small-diameter pores 26 that communicate with the bottoms of the large-diameter pores 24 and extend from the communication positions to a depth of 20 nm to 2,000 nm. Specifically, for example, the embodiments described in paragraphs 0107 to 0114 of JP-A-2019-162855 can be used.

[0515] <<Method for Producing Support>> A preferred method for producing a support used in the present disclosure involves, for example, performing the following steps in order: Surface roughening step: a step of roughening an aluminum plate; Anodizing step: anodizing the surface-roughened aluminum plate; Pore widening step: a step of contacting the aluminum plate having the anodized film obtained in the anodizing step with an acid aqueous solution or an alkaline aqueous solution to enlarge the diameter of micropores in the anodized film. The procedure of each step is described in detail below.

[0516] <<Surface Roughening Treatment Step>> The surface roughening treatment step is a step of performing a surface roughening treatment, including electrochemical surface roughening treatment, on the surface of an aluminum plate. This step is preferably performed before the anodizing treatment step described below, but may not be performed if the surface of the aluminum plate already has a preferred surface shape. This can be performed by the method described in paragraphs 0086 to 0101 of JP 2019-162855 A.

[0517] <<Anodizing Treatment Step>> The procedure for the anodizing treatment step is not particularly limited as long as the above-described micropores can be obtained, and known methods can be used. In the anodizing treatment step, an aqueous solution of sulfuric acid, phosphoric acid, oxalic acid, or the like can be used as the electrolytic bath. For example, the sulfuric acid concentration can be 100 g / L to 300 g / L. The anodizing treatment conditions are appropriately set depending on the electrolytic solution used, but for example, a solution temperature of 5°C to 70°C (preferably 10°C to 60°C), a current density of 0.5 A / dm ２ ~60 A / dm ２ (preferably 1 A / dm ２ ~60 A / dm ２ ), voltage 1V to 100V (preferably 5V to 50V), electrolysis time 1 second to 100 seconds (preferably 5 seconds to 60 seconds), and coating amount 0.1 g / m ２ ~5g / m ２ (preferably 0.2 g / m ２ ~3g / m ２ ) are listed.

[0518] <<Pore Widening Treatment>> Pore widening treatment is a treatment (i.e., pore size enlargement treatment) that enlarges the diameter (i.e., pore diameter) of micropores present in the anodized coating formed by the above-mentioned anodizing treatment step. The pore widening treatment can be carried out by contacting the aluminum plate obtained by the above-mentioned anodizing treatment step with an acid aqueous solution or an alkaline aqueous solution. The contact method is not particularly limited, and examples include immersion and spraying.

[0519] The support may have, if necessary, a backcoat layer containing an organic polymer compound described in JP-A-5-45885 or a silicon alkoxy compound described in JP-A-6-35174 on the surface opposite to the image recording layer.

[0520] <Undercoat Layer> The lithographic printing plate precursor according to the present disclosure preferably has an undercoat layer (sometimes referred to as an intermediate layer) between the image recording layer and the support. The undercoat layer strengthens adhesion between the support and the image recording layer in exposed areas and facilitates peeling of the image recording layer from the support in unexposed areas, thereby contributing to improving developability while suppressing a decrease in printing durability. In addition, in the case of infrared laser exposure, the undercoat layer functions as a heat insulating layer, thereby preventing heat generated by exposure from diffusing to the support and reducing sensitivity.

[0521] The compound used in the undercoat layer may be a polymer having an adsorptive group and a hydrophilic group capable of adsorbing to the support surface. In order to improve adhesion to the image recording layer, a polymer having an adsorptive group and a hydrophilic group and further having a crosslinkable group is preferred. The compound used in the undercoat layer may be a low molecular weight compound or a polymer. Two or more compounds may be mixed together as needed.

[0522] When the compound used in the undercoat layer is a polymer, a copolymer of a monomer having an adsorptive group, a monomer having a hydrophilic group, and a monomer having a crosslinkable group is preferred. Examples of the adsorptive group that can be adsorbed onto the support surface include a phenolic hydroxy group, a carboxy group, a -PO ３ H ２ , -OPO ３ H ２ , -CONHSO ２ -, -SO ２ NHSO ２ --, --COCH ２ COCH ３is preferred. As the hydrophilic group, a sulfo group or a salt thereof, or a salt of a carboxy group is preferred. As the crosslinkable group, an acryl group, a methacryl group, an acrylamide group, a methacrylamide group, an allyl group, or the like is preferred. The polymer may have a crosslinkable group introduced by salt formation between a polar substituent of the polymer and a compound having an ethylenically unsaturated bond and a substituent having an opposite charge to the polar substituent, or may be further copolymerized with a monomer other than the above, preferably a hydrophilic monomer.

[0523] Specifically, preferred examples include silane coupling agents having an addition-polymerizable ethylenic double bond reactive group, as described in JP-A-10-282679, and phosphorus compounds having an ethylenic double bond reactive group, as described in JP-A-2-304441. Also preferred are low-molecular-weight or high-molecular-weight compounds having a crosslinkable group (preferably an ethylenically unsaturated bond group), a functional group that interacts with the support surface, and a hydrophilic group, as described in JP-A-2005-238816, JP-A-2005-125749, JP-A-2006-239867, and JP-A-2006-215263. More preferred examples include high-molecular-weight polymers having an adsorptive group, a hydrophilic group, and a crosslinkable group that can be adsorbed to the support surface, as described in JP-A-2005-125749 and JP-A-2006-188038.

[0524] The content of ethylenically unsaturated bond groups in the polymer used in the undercoat layer is preferably 0.1 mmol to 10.0 mmol, more preferably 0.2 mmol to 5.5 mmol, per 1 g of the polymer. The weight-average molecular weight (Mw) of the polymer used in the undercoat layer is preferably 5,000 or more, more preferably 10,000 to 300,000.

[0525] In addition to the above-described compounds for use in an undercoat layer, the undercoat layer may contain, in order to prevent staining over time, a chelating agent, a secondary or tertiary amine, a polymerization inhibitor, a compound having an amino group or a functional group having polymerization inhibitory ability and a group that interacts with the support surface (e.g., 1,4-diazabicyclo[2.2.2]octane (DABCO), 2,3,5,6-tetrahydroxy-p-quinone, chloranil, sulfophthalic acid, hydroxyethylethylenediaminetriacetic acid, dihydroxyethylethylenediaminediacetic acid, hydroxyethyliminodiacetic acid, etc.), and the like.

[0526] The undercoat layer is applied by a known method. The coating amount (solid content) of the undercoat layer is 0.1 mg / m ２ ~100 mg / m ２ is preferred, and 1 mg / m ２ ~30 mg / m ２ is more preferred.

[0527] <Outermost layer> The lithographic printing plate precursor according to the present disclosure may have an outermost layer (sometimes referred to as a "protective layer" or "overcoat layer") on the surface of the image recording layer opposite the support side. Furthermore, the lithographic printing plate precursor according to the present disclosure preferably has a support, an image recording layer, and an outermost layer in this order. The outermost layer may have the function of preventing scratches on the image recording layer and ablation during exposure to high-intensity laser light, in addition to the function of blocking oxygen to suppress image formation inhibiting reactions.

[0528] The outermost layer may be a known outermost layer ("protective layer" or "overcoat layer") in an on-press development type lithographic printing plate precursor. Specifically, the outermost layer described in paragraphs 0444 to 0462 of WO 2022 / 019217 can be suitably used.

[0529] The lithographic printing plate precursor according to the present disclosure may have layers other than those described above. The other layers are not particularly limited, and known layers may be included. For example, a backcoat layer may be provided on the side of the support opposite to the image recording layer side, as needed.

[0530] (Method for preparing a lithographic printing plate and a lithographic printing method) A lithographic printing plate can be prepared by imagewise exposing the lithographic printing plate precursor according to the present disclosure and developing it. The method for preparing a lithographic printing plate according to the present disclosure preferably includes a step of imagewise exposing the on-press development type lithographic printing plate precursor according to the present disclosure (hereinafter also referred to as an "exposure step"), and a step of supplying at least one selected from the group consisting of printing ink and fountain solution on a printing press to remove the image recording layer in non-image areas (hereinafter also referred to as an "on-press development step"). The lithographic printing method according to the present disclosure preferably includes a step of imagewise exposing the on-press development type lithographic printing plate precursor according to the present disclosure (i.e., the exposure step), a step of supplying at least one selected from the group consisting of printing ink and fountain solution to remove the image recording layer in non-image areas on a printing press to prepare a lithographic printing plate (i.e., the on-press development step), and a step of printing with the obtained lithographic printing plate (i.e., a printing step).

[0531] Further, a method for producing a lithographic printing plate according to the present disclosure includes a step of imagewise exposing an on-press development type lithographic printing plate precursor to an infrared laser, and a step of supplying at least one selected from the group consisting of printing ink and fountain solution on a printing press to remove the image recording layer in a non-image area, wherein the on-press development type lithographic printing plate precursor has a support and an image recording layer on the support, the image recording layer contains an infrared absorber capable of donating an electron to the initiator, and a color former precursor, and the energy density of the infrared laser exposure at a wavelength of 830 nm is 110 mJ / cm. ２and a method for producing a lithographic printing plate, in which when the image recording layer is exposed to an infrared laser, the change in lightness ΔL of the image recording layer before and after the exposure is 3.0 or more. Furthermore, the method for producing a lithographic printing plate according to the present disclosure preferably comprises the steps of imagewise exposing an on-press developable lithographic printing plate precursor to an infrared laser, and supplying at least one selected from the group consisting of printing ink and fountain solution on a printing press to remove the image recording layer in non-image areas, wherein the on-press developable lithographic printing plate precursor has a support and an image recording layer on the support, the image recording layer contains an initiator, an infrared absorber, and a color former precursor, and the image recording layer satisfies the following formula L: 2.0≦L1−L0 Formula L In formula L, L1 represents the visibility of the image recording layer, and L0 represents the visibility of a layer that is the same as the image recording layer except for the absence of the color former precursor. Furthermore, with regard to the lithographic printing method according to the present disclosure, each of these aspects preferably further includes the printing step described above.

[0532]

[0033] Preferred aspects of each step in the method for preparing a lithographic printing plate according to the present disclosure and the lithographic printing method according to the present disclosure will be described below in order. The lithographic printing plate precursor according to the present disclosure can also be developed using a developer. The exposure step and on-press development step in the method for preparing a lithographic printing plate according to the present disclosure are the same step, and the on-press development step in the method for preparing a lithographic printing plate according to the present disclosure is the same step.

[0533] <Exposure Step> The method for producing a lithographic printing plate according to the present disclosure preferably includes an exposure step of imagewise exposing the lithographic printing plate precursor according to the present disclosure to form exposed and unexposed areas. The lithographic printing plate precursor according to the present disclosure is preferably exposed to laser light through a transparent original having a line image, a halftone dot image, or the like, or imagewise by laser light scanning using digital data. The wavelength of the light source used is preferably 750 nm to 1,400 nm. As a light source with a wavelength of 750 nm to 1,400 nm, a solid-state laser or semiconductor laser that emits infrared light is suitable. With regard to the infrared laser, the output is preferably 100 mW or more, the exposure time per pixel is preferably 20 microseconds or less, and the irradiation energy amount is 10 mJ / cm. ２ ~300 mJ / cm ２ It is preferable to use a multi-beam laser device to shorten the exposure time. The exposure mechanism may be any of an internal drum system, an external drum system, a flatbed system, etc. Image exposure can be carried out by a conventional method using a plate setter or the like. In the case of on-press development, the lithographic printing plate precursor may be mounted on a printing press and then image exposure may be carried out on the printing press.

[0534] <On-Press Development Step> The method for producing a lithographic printing plate according to the present disclosure preferably includes an on-press development step of supplying at least one selected from the group consisting of printing ink and fountain solution on a printing press to remove the image-recording layer in non-image areas.

[0535] [On-Press Development Method] In the on-press development method, an image-wise exposed lithographic printing plate precursor is preferably supplied with an oil-based ink and an aqueous component on a printing press, and the image-recording layer in non-image areas is removed to produce a lithographic printing plate. That is, after image-wise exposure, the lithographic printing plate precursor is either mounted on a printing press as is without any development treatment, or the lithographic printing plate precursor is mounted on a printing press, image-wise exposed on the press, and then oil-based ink and an aqueous component are supplied to print. In the early stages of printing, the uncured image-recording layer in the non-image areas is dissolved or dispersed by either or both of the supplied oil-based ink and aqueous component, thereby exposing a hydrophilic surface in those areas. Meanwhile, in the exposed areas, the image-recording layer cured by exposure forms an oil-based ink-receptive area with an oleophilic surface. Either an oil-based ink or an aqueous component may be supplied first to the plate surface, but it is preferable to supply the oil-based ink first to prevent contamination of the aqueous component with the components of the image-recording layer from which the aqueous component has been removed. In this way, the lithographic printing plate precursor is developed on the press and used as is for printing a large number of sheets. As the oil-based ink and aqueous component, printing ink and fountain solution for ordinary lithographic printing are preferably used.

[0536] The laser used for imagewise exposure of the lithographic printing plate precursor according to the present disclosure preferably has a light source wavelength of 300 nm to 450 nm or 750 nm to 1,400 nm. In the case of a light source of 300 nm to 450 nm, a lithographic printing plate precursor containing in an image recording layer a sensitizing dye having an absorption maximum in this wavelength region is preferably used, and for a light source of 750 nm to 1,400 nm, the above-mentioned light sources are preferably used. As a light source of 300 nm to 450 nm, a semiconductor laser is suitable.

[0537] <Printing Step> The lithographic printing method according to the present disclosure includes a printing step in which printing ink is supplied to a lithographic printing plate to print a recording medium. The printing ink is not particularly limited, and various known inks can be used as desired. Examples of preferred printing inks include oil-based inks and ultraviolet-curable inks (i.e., UV inks). In the printing step, dampening water may be supplied as needed. The printing step may be performed consecutively to the on-press development step without stopping the printing press. The recording medium is not particularly limited, and known recording media can be used as desired.

[0538] In the method for preparing a lithographic printing plate from a lithographic printing plate precursor according to the present disclosure and the lithographic printing method according to the present disclosure, the entire surface of the lithographic printing plate precursor may be heated, as necessary, before exposure, during exposure, or between exposure and development. Such heating promotes the image formation reaction in the image recording layer, resulting in advantages such as improved sensitivity and printing durability and stabilized sensitivity. Heating before development is preferably carried out under mild conditions at 150°C or less. This embodiment can prevent problems such as hardening of non-image areas. Heating after development is preferably carried out under very strong conditions, preferably in the range of 100°C to 500°C. Within this range, sufficient image strengthening effect can be obtained and problems such as support degradation and thermal decomposition of image areas can be suppressed.

[0539] <Compounds Represented by Formula (I) and Formula (II)> The compounds represented by formula (I) and formula (II) are both novel compounds and can be suitably used as electron-donating polymerization initiators. Details and preferred embodiments of the compound represented by formula (I) and the compound represented by formula (II) as novel compounds are the same as those described above in the description of the borate compound represented by formula (1) or the borate compound represented by formula (1a). Among these, preferred novel compounds include compounds represented by the following B-7, B-25, B-26, B-29, and B-30.

[0540]

[0541] The present disclosure will be described in detail below using examples, but the present disclosure is not limited thereto. In these examples, "%" and "parts" mean "% by mass" and "parts by mass", respectively, unless otherwise specified. In addition, in polymer compounds, unless otherwise specified, the molecular weight is the weight average molecular weight (Mw), and the ratio of the constituent repeating units is expressed as a molar percentage. In addition, the weight average molecular weight (Mw) is a value measured as a polystyrene equivalent value by gel permeation chromatography (GPC).

[0542] <Synthesis of borate compounds represented by formula (1) (specific borate compounds)> Examples of synthesis of borate compounds represented by formula (1) are shown below. The structure of each compound was identified by nuclear magnetic resonance analysis.

[0543] Example 1-1: Synthesis of Compound B-2 To 1.2 g of magnesium, 22 g of tetrahydrofuran and 0.01 g of iodine were added, and the magnesium was activated with stirring. To this was added 8.1 g of 1-bromo-4-tert-butylbenzene to prepare a Grignard reagent. 7.8 g of trifluoroborane-diethyl ether complex (46%) was diluted with 22 g of toluene. 10 mL of a phenylmagnesium bromide-diethyl ether solution (3 M), 3.5 mL of p-methoxyphenylmagnesium bromide (1 M), and 3.5 mL of p-methylphenylmagnesium bromide (1 M) were added. After stirring for 30 minutes at room temperature, the Grignard reagent was added. After confirming the completion of the reaction, the mixture was added to a saturated aqueous sodium carbonate solution, and the tetrahydrofuran (THF) layer was evaporated and then reslurried with toluene to obtain 2 g of a white solid.

[0544] [Examples 1-2 to 1-20: Synthesis of Compounds B-3 to B-5, B-7 to B-17, B-20, B-21, B-24, B-26, B-29, and B-30] Each compound was synthesized in the same manner as in Example 1-1, except that p-isopropylphenylboronic acid was changed to a boronic acid appropriate for each compound.

[0545] Example 1-21 Synthesis of Compound B-25 5 g of p-tert-butylphenylboronic acid, 7.5 g of methyl orthoformate, and 0.4 g of concentrated hydrochloric acid were added and stirred at room temperature, and then the reaction by-products, methanol and methyl formate, were distilled off. 50 mL of p-fluorophenylmagnesium bromide (1 M) was added thereto, and the temperature was raised to 60°C. After confirming the completion of the reaction, the mixture was added to a saturated aqueous sodium carbonate solution, and the THF layer was distilled off, followed by reslurrying with toluene to obtain 3 g of a white solid.

[0546] Examples 1-22 and 1-23: Synthesis of Compounds B-27 and B-28 Compounds B-27 and B-28 were synthesized in the same manner as in Example 1-21, except that the corresponding bromide and iodonium salt in Example 1-21 were changed.

[0547] Example 1-24: Synthesis of Compound B-34 To 1.2 g of magnesium, 22 g of tetrahydrofuran and 0.01 g of iodine were added, and the magnesium was activated with stirring. 8.1 g of 1-bromo-4-tert-butylbenzene was added to prepare a Grignard reagent. 7.8 g of trifluoroborane-diethyl ether complex (46%) was diluted with 22 g of toluene. 29 mL of a phenylmagnesium bromide-diethyl ether solution (3 M) was added to the mixture, and the mixture was stirred at room temperature for 30 minutes, after which the Grignard reagent was added. After confirming the completion of the reaction, the mixture was added to a saturated aqueous sodium carbonate solution, and the THF layer was distilled off, followed by reslurrying with toluene to obtain 4.5 g of a white solid. 1 g of the white solid and 1 g of the following infrared absorber (IR-3) were dissolved in 8 mL of acetone and added to 24 mL of methanol. The resulting crystals were filtered and washed with methanol to obtain 1 g of Compound B-31.

[0548] [Examples 1-25 to 1-34: Synthesis of compounds B-35 to B-44] Compounds B-35 to B-44 were synthesized in the same manner as in Example 1-24, except that the corresponding borate compound and the infrared absorber described later were used.

[0549] For borate compounds other than those mentioned above, the target compounds were obtained by reaction using the corresponding boronic acid compounds and magnesium bromide compounds as raw materials, with reference to the above method.

[0550] <Synthesis of borate compound represented by formula (1a)> Examples of synthesis of the compound represented by formula (1a) are shown below. The structure of each compound was identified by nuclear magnetic resonance analysis.

[0551] Example 2-1: Synthesis of Compound B-19 To 1.2 g of magnesium, 22 g of tetrahydrofuran and 0.01 g of iodine were added, and the magnesium was activated with stirring. To this was added 8.1 g of 1-bromo-4-tert-butylbenzene to prepare a Grignard reagent. 3.9 g of trimethoxyborane-diethyl ether complex (46%) was diluted with 22 g of toluene, and 29 mL of a phenylmagnesium bromide-diethyl ether solution (3 M) was added. After stirring at room temperature for 30 minutes, the Grignard reagent was added. After confirming the completion of the reaction, the mixture was added to a saturated aqueous sodium carbonate solution, and then 20 g of bis(4-tert-butylphenyl)iodonium hexafluorophosphate was added. The THF layer was then distilled off, and the mixture was reslurried in methanol to obtain 5 g of a white solid.

[0552] Example 2-2: Synthesis of compound B-18 Compound B-18 was synthesized in the same manner as in Example 2-1, except that the corresponding bromides and iodonium salts were used instead.

[0553] Example 2-3 Synthesis of Compound B-45 Compound B-45 was synthesized in the same manner as in Example 2-1, except that Bis(4-tert-butylphenyl)iodonium hexafluorophosphate in Example 2-1 was changed to (4-octoxyphenyl)-(2,4,6-trimethoxyphenyl)iodonium 4-methylbenzenesulfonate.

[0554] Example 2-4 Synthesis of Compound B-46 Compound B-46 was synthesized in the same manner as in Example 2-1, except that 1-bromo-4-tert-butylbenzene was changed to 1-bromo-4-methylbenzene.

[0555] For borate compounds other than those mentioned above, the corresponding bromides and iodonium salts were used as raw materials to carry out the reaction, and the target compounds were obtained.

[0556] [Examples 3-1 to 3-52, Examples 4-1 to 4-11, and Comparative Examples 1-1 to 1-4, and 2-1] <Preparation of Support> (a) Alkali Etching Treatment An aluminum plate was etched by spraying an aqueous solution of caustic soda containing 26% by mass of caustic soda and 6.5% by mass of aluminum ions onto the aluminum plate at a temperature of 70°C. The aluminum was then rinsed with water by spraying. The amount of dissolved aluminum on the surface to be subsequently subjected to electrochemical graining treatment was 5 g / m ２ It was.

[0557] (b) Desmutting Treatment Using Acidic Aqueous Solution (First Desmutting Treatment) Next, a desmutting treatment was performed using an acidic aqueous solution. The acidic aqueous solution used in the desmutting treatment was an aqueous solution containing 150 g / L of sulfuric acid. The liquid temperature was 30°C. The acidic aqueous solution was sprayed onto the aluminum plate, and the desmutting treatment was performed for 3 seconds. Thereafter, a water rinsing treatment was performed.

[0558] (c) Electrochemical Graining Treatment Next, electrochemical graining treatment was performed using an electrolytic solution with a hydrochloric acid concentration of 14 g / L, an aluminum ion concentration of 13 g / L, and a sulfuric acid concentration of 3 g / L, using an alternating current. The temperature of the electrolytic solution was 30°C. The aluminum ion concentration was adjusted by adding aluminum chloride. The waveform of the alternating current was a sine wave with symmetrical positive and negative waveforms, a frequency of 50 Hz, the anode reaction time and cathode reaction time in one cycle of the alternating current being 1:1, and the current density was 75 A / dm at the peak current value of the alternating current waveform. ２ The total amount of electricity that the aluminum plate takes in the anode reaction is 450 C / dm ２ and the electrolysis temperature is 112.5 C / dm ２The test was carried out four times with a 4-second interval between each test. A carbon electrode was used as the counter electrode for the aluminum plate. After that, the plate was washed with water.

[0559] (d) Alkali Etching Treatment After electrochemical graining, the aluminum plate was etched by spraying an aqueous solution of caustic soda containing 5% by mass of caustic soda and 0.5% by mass of aluminum ions at a temperature of 45°C. The amount of dissolved aluminum on the surface subjected to electrochemical graining was 0.2 g / m ２ After that, a water washing treatment was carried out.

[0560] (e) Desmutting Treatment Using Acidic Aqueous Solution Next, a desmutting treatment was performed using an acidic aqueous solution. Specifically, the acidic aqueous solution was sprayed onto the aluminum plate for 3 seconds. The acidic aqueous solution used for the desmutting treatment had a sulfuric acid concentration of 170 g / L and an aluminum ion concentration of 5 g / L. The liquid temperature was 30°C.

[0561] (f) First-Stage Anodizing Treatment A first-stage anodizing treatment (also referred to as first anodizing treatment) was performed using an anodizing treatment apparatus 610 using direct current electrolysis having the structure shown in FIG. 3 . Specifically, the first anodizing treatment was performed under the conditions listed in the "First Anodizing Treatment" column in Table 1 below, and an anodized film of a predetermined thickness was formed. The anodizing treatment apparatus 610 shown in FIG. 3 will now be described. In the anodizing treatment apparatus 610 shown in FIG. 3 , an aluminum sheet 616 is conveyed as indicated by the arrow in FIG. 3 . In a power supply tank 612 containing an electrolytic solution 618, the aluminum sheet 616 is positively charged by a power supply electrode 620. The aluminum sheet 616 is then conveyed upward in the power supply tank 612 by rollers 622, redirected downward by nip rollers 624, and conveyed toward an electrolytic treatment tank 614 containing an electrolytic solution 626, where it is redirected horizontally by rollers 628. Next, the aluminum plate 616 is negatively charged by the electrolysis electrode 630, thereby forming an anodized film on its surface, and the aluminum plate 616 leaves the electrolysis bath 614 and is transported to a subsequent process. In the anodization device 610, a roller 622, a nip roller 624, and a roller 628 form a direction-changing means, and the aluminum plate 616 is transported in a mountain-like and inverted U-like shape by the rollers 622, 624, and 628 in the area between the power supply bath 612 and the electrolysis bath 614. The power supply electrode 620 and the electrolysis electrode 630 are connected to a DC power supply 634.

[0562] (g) Pore Widening Treatment The anodized aluminum plate was subjected to a pore widening treatment by immersing it in an aqueous solution of caustic soda having a temperature of 40°C, a caustic soda concentration of 5 mass%, and an aluminum ion concentration of 0.5 mass% under the conditions shown in Table 1 below. Thereafter, the plate was washed with water by spraying.

[0563] (h) Second Anodizing Treatment A second stage of anodizing treatment (also referred to as second anodizing treatment) was performed using an anodizing treatment apparatus 610 using direct current electrolysis having the structure shown in Fig. 3. Specifically, the second anodizing treatment was performed under the conditions shown in the "Second Anodizing Treatment" column in Table 1 below, and an anodized film of a predetermined film thickness was formed.

[0564] In this way, a support was prepared. The L of the micropore anodized film surface of the obtained support was ＊ a ＊ b ＊ Lightness L in the color system ＊ The average diameter and depth of the oxide film surface of the large-diameter micropores, the average diameter (nm) and depth of the small-diameter micropores at the communicating positions, the depth (nm) of the large-diameter and small-diameter micropores, the micropore density, and the thickness of the anodized film from the bottom of the small-diameter micropores to the surface of the aluminum plate (also referred to as film thickness) are summarized in Table 2. In Table 1, the film amount (AD) in the first anodizing treatment column and the film amount (AD) in the second anodizing treatment column represent the film amount obtained by each treatment. The electrolyte used is an aqueous solution containing the components shown in Table 1.

[0565]

[0566]

[0567] In Example 3-47, the following support B was used.

[0568] <Preparation of Support B> An aluminum plate (aluminum alloy plate) having a thickness of 0.3 mm and a material of 1S was subjected to the following treatments to produce Support 1. Note that a water-rinsing treatment was performed between all treatment steps, and after the water-rinsing treatment, the liquid was removed using nip rollers.

[0569] - Alkali Etching Treatment (1) - An aluminum plate was etched by spraying an aqueous solution of caustic soda with a caustic soda concentration of 26% by mass and an aluminum ion concentration of 6.5% by mass onto the aluminum plate at a temperature of 70°C. The aluminum was then rinsed with water by spraying. The amount of dissolved aluminum on the surface to be subsequently subjected to electrochemical graining treatment was 5 g / m. ２ It was.

[0570] - Desmutting Treatment Using Acidic Aqueous Solution (1) - Next, a desmutting treatment was carried out using an acidic aqueous solution. Specifically, the acidic aqueous solution was sprayed onto the aluminum plate with a sprayer, and the desmutting treatment was carried out for 3 seconds. The acidic aqueous solution used in the desmutting treatment was an aqueous solution containing 150 g / L of sulfuric acid. The liquid temperature was 30°C.

[0571] -Hydrochloric Acid Electrolysis- Next, hydrochloric acid electrolysis was performed using an electrolytic solution with a hydrochloric acid concentration of 13 g / L, an aluminum ion concentration of 15 g / L, and a sulfuric acid concentration of 1.0 g / L, using an alternating current. The temperature of the electrolytic solution was 25°C. The aluminum ion concentration was adjusted by adding aluminum chloride. The waveform of the alternating current was a sine wave with symmetrical positive and negative waveforms, the frequency was 50 Hz, the anode reaction time and cathode reaction time in one cycle of the alternating current were 1:1, and the current density was 35 A / dm at the peak current value of the alternating current waveform. ２ The total amount of electricity that the aluminum plate takes in the anode reaction is 320 C / dm ２ The electrolytic treatment was 80 C / dm ２ The test was carried out four times with a 2.5 second interval between each test. A carbon electrode was used as the counter electrode for the aluminum plate. After that, the plate was washed with water.

[0572] - Alkali Etching Treatment (2) - After the hydrochloric acid electrolysis, the aluminum plate was etched by spraying an aqueous solution of caustic soda containing 5% by mass of caustic soda and 0.5% by mass of aluminum ions at a temperature of 45°C. The amount of dissolved aluminum on the surface that had been subjected to the hydrochloric acid electrolysis was 0.1 g / m ２ After that, a water washing treatment was carried out.

[0573] - Desmutting Treatment Using Acidic Aqueous Solution (2) - Next, a desmutting treatment was carried out using an acidic aqueous solution. Specifically, the acidic aqueous solution was sprayed onto the aluminum plate, and the desmutting treatment was carried out for 3 seconds. The acidic aqueous solution used in the desmutting treatment had a sulfuric acid concentration of 170 g / L and an aluminum ion concentration of 5 g / L. The liquid temperature was 35°C.

[0574] - First-stage anodizing treatment - The first-stage anodizing treatment was carried out using an anodizing apparatus using direct current electrolysis with the structure shown in Figure 3. A 170 g / L aqueous sulfuric acid solution was used as the electrolytic solution, and the solution temperature was 40°C and the current density was 20 A / dm ２ Anodizing treatment was carried out under the conditions of ２ An anodic oxide film was formed.

[0575] -Pore widening treatment- The anodized aluminum plate was immersed in an aqueous solution of caustic soda with a caustic soda concentration of 5% by mass and an aluminum ion concentration of 0.5% by mass at 40°C for 5 seconds to perform a pore widening treatment. Thereafter, the plate was rinsed with water by spraying.

[0576] - Second-stage anodizing treatment - The second-stage anodizing treatment was carried out using an anodizing apparatus using direct current electrolysis with the structure shown in Figure 3. A 170 g / L aqueous sulfuric acid solution was used as the electrolytic solution, the solution temperature was 50°C, and the current density was 13 A / dm ２ Anodizing treatment was carried out under the conditions of ２ An anodic oxide film was formed.

[0577] -Silicate Treatment- The aluminum plate that had been subjected to the second anodizing treatment was immersed for 12 seconds in a No. 3 sodium silicate aqueous solution with a concentration of 5% by mass and a liquid temperature of 65°C to obtain Support B. The amount of Si deposited on Support B was 21 mg / m ２ It was.

[0578] <Formation of Undercoat Layer> Undercoat layer coating solution A or B having the following composition was applied to the obtained support in a dry coating amount of 0.1 g / m ２ The undercoat layer was formed by coating the mixture in such a manner that the thickness of the undercoat layer became 1 / 4.

[0579] - Coating Solution A for Undercoat Layer - Coating Solution A for undercoat layer was prepared by mixing the following components: Undercoat layer compound (U-1 below, 11% aqueous solution): 0.0788 parts; Hydroxyethyldiiminodiacetic acid: 0.0280 parts; Sodium ethylenediaminetetraacetate tetrahydrate: 0.0499 parts; Surfactant (Emalex (registered trademark) 710, Nippon Emulsion Co., Ltd.): 0.0016 parts; Preservative (BioHope L, K.I. Kasei Co., Ltd.): 0.0015 parts; Water: 2.8701 parts

[0580] - Coating Solution B for Undercoat Layer - Coating Solution B for undercoat layer was prepared by mixing the following components: Undercoat layer compound (U-1 below, 11% aqueous solution): 0.0788 parts Sodium gluconate: 0.0700 parts Surfactant (Emalex (registered trademark) 710, Nippon Emulsion Co., Ltd.): 0.0016 parts Preservative (BioHope L, K.I. Kasei Co., Ltd.): 0.0015 parts Water: 2.870 parts

[0581]

[0582] <Formation of Image Recording Layer> For Examples 3-3, 3-4, 3-8 to 3-38, 3-40 to 3-52, 4-1 to 4-11, Comparative Examples 1-1 to 1-4, and 2-1, the following image recording layer coating solution was applied onto the undercoat layer with a bar, and dried in an oven at 120°C for 40 seconds to obtain a dry coating amount of 1.0 g / m ２ In the examples other than those described above, the following image recording layer coating solution was applied to the support with a bar, and dried in an oven at 120°C for 40 seconds to form an image recording layer with a dry coating amount of 1.0 g / m ２ An image recording layer of the above formula was formed.

[0583] -Image Recording Layer Coating Liquid- A coating liquid for the image recording layer etc. was prepared by mixing the following components. Electron-donating polymerization initiators described in Tables 3 to 9: amounts described in Tables 3 to 9. Infrared absorbers described in Tables 3 to 9: amounts described in Tables 3 to 9. Electron-accepting polymerization initiators described in Tables 3 to 9: amounts described in Tables 3 to 9. Polymerizable compounds described in Tables 3 to 9: amounts described in Tables 3 to 9. Polymer particles described in Tables 3 to 9: amounts described in Tables 3 to 9. Binder polymers described in Tables 3 to 9: amounts described in Tables 3 to 9. Color formers described in Tables 3 to 9: amounts described in Tables 3 to 8. Phenothiazine: amounts described in Tables 3 to 9. Oil agent (tricresyl phosphate (tricresyl phosphate)): amounts described in Tables 3 to 9. Surfactants described in Table 4: amounts described in Table 4. Anionic surfactant (A-1): 0.0162 parts. Fluorine-based surfactant (W-1): 0.0042 parts. 2-butanone: 5.3155 parts. 1-Methoxy-2-propanol: 2.8825 parts Methanol: 2.3391 parts

[0584] The electron-donating polymerization initiators (that is, specific borate compounds or comparative compounds) listed in Tables 3 to 9 are as follows:

[0585]

[0586]

[0587]

[0588]

[0589]

[0590]

[0591]

[0592]

[0593]

[0594] [Infrared absorbers] IR-1 to IR-17: Compounds having the following structures

[0595]

[0596]

[0597]

[0598]

[0599]

[0600] [Electron-accepting polymerization initiator] Int-1: Compound having the following structure Int-2: Compound having the following structure Int-3: Compound having the following structure Int-4: Compound having the following structure Int-5: Compound having the following structure

[0601]

[0602] [Polymerizable Compounds] M-1: Compound having the following structure M-2: Compound having the following structure M-3: Dipentaerythritol pentaacrylate (SR-399, manufactured by Sartomer Corporation) M-4: Urethane acrylate (U-15HA, manufactured by Shin-Nakamura Chemical Co., Ltd.) M-5: Monomer synthesized by the following synthesis method

[0603]

[0604] <Synthesis of M-5> A mixed solution of Takenate D-160N (polyisocyanate trimethylolpropane adduct, manufactured by Mitsui Chemicals, Inc., 4.7 parts), Aronix M-403 (manufactured by Toagosei Co., Ltd., an amount such that the NCO value of Takenate D-160N and the hydroxyl value of Aronix M-403 were 1:1), t-butylbenzoquinone (0.02 parts), and methyl ethyl ketone (11.5 parts) was heated to 65°C. To the reaction solution, Neostan U-600 (bismuth-based polycondensation catalyst, manufactured by Nitto Kasei Co., Ltd., 0.11 parts) was added, and the mixture was heated at 65°C for 4 hours. The reaction solution was cooled to room temperature (25°C), and methyl ethyl ketone was added to synthesize a urethane acrylate solution with a solids content of 50% by mass. Using a recycle-type GPC (instrument: LC908-C60, columns: JAIGEL-1H-40 and 2H-40 (manufactured by Japan Analytical Industry Co., Ltd.)), molecular weight fractionation of the urethane acrylate solution (M-5) was carried out with an eluent of tetrahydrofuran (THF). The weight average molecular weight was 20,000.

[0605] [Polymer Particles] <Preparation of Polymer Particles R-1> Microgel (polymer particles R-1): 2.640 parts Distilled water: 2.425 parts The method for preparing the microgel is as follows.

[0606] - Preparation of Polyisocyanate Compound - 0.043 parts of bismuth ...

Claims

1. An on-press development type lithographic printing plate precursor having a support and an image recording layer on the support, the image recording layer comprising the following (1) or (2): (1) a borate compound represented by the following formula (1) and an electron-accepting polymerization initiator: In formula (1), R １ , R ２ , R ３ , and R ４ each independently represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted alkenyl group, or a substituted or unsubstituted alkynyl group; R １ , R ２ , R ３ , and R ４ may each independently have a ring structure. １ , R ２ , R ３ , and R ４ At least one of the M ＋ represents a cation. (2) A borate compound represented by the following formula (1a): In formula (1a), R １ , R ２ , R ３ , and R ４ each independently represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted alkenyl group, or a substituted or unsubstituted alkynyl group; R １ , R ２ , R ３ , and R ４ may each independently have a ring structure. １ , R ２ , R ３ , and R ４ At least one of them is different from the others. ＋ represents an iodonium cation.

2. R in the formula (1) or the formula (1a) １ , R ２ , and R ３ is a phenyl group, R ４ But, R １ , R ２ , and R ３ The on-press development type lithographic printing plate precursor according to claim 1 , 3. R ​​in the formula (1) or the formula (1a) １ , R ２ , and R ３ is a phenyl group, R ４ The on-press development type lithographic printing plate precursor according to claim 1 or 2, wherein is an aryl group having a substituent.

4. The M in the formula (1) ＋ The on-press development type lithographic printing plate precursor according to claim 1 or 2, wherein: is an inorganic cation.

5. The M in the formula (1) ＋ The on-press development type lithographic printing plate precursor according to claim 1 or 2, wherein is at least one cation selected from the group consisting of iodonium cations and infrared absorbing dye cations.

6. R in the formula (1) or the formula (1a) １ , R ２ , and R ３ is a phenyl group, R ４ The on-press development type lithographic printing plate precursor according to claim 3 , wherein: is a substituted aryl group, and the total number of carbon atoms and oxygen atoms in the substituent is 2 or more.

7. The on-press development type lithographic printing plate precursor according to claim 6, wherein the total number of carbon atoms and oxygen atoms in the substituent is 3 or more.

8. R in the formula (1) or the formula (1a) １ , R ２ , and R ３ is a phenyl group substituted with an electron-withdrawing group, R ４ But, R １ , R ２ , and R ３ The on-press development type lithographic printing plate precursor according to claim 2 , wherein R 1 is a group different from R 2 .

9. R in the formula (1) or the formula (1a) ４ The on-press development type lithographic printing plate precursor according to claim 3 , wherein the substituent of is at least one group selected from the group consisting of an alkyl group, an aryl group, an alkenyl group, an alkoxy group, an ester group, a carbonyl group, and an amide group.

10. The on-press development type lithographic printing plate precursor according to claim 1 or 2, wherein the image recording layer contains a color former.

11. The on-press development type lithographic printing plate precursor according to claim 1 or 2, wherein the image recording layer contains an infrared absorbing agent.

12. An on-press development type lithographic printing plate precursor according to claim 1 or 2, wherein the electron-accepting polymerization initiator comprises a compound represented by the following formula (Ia) and at least one compound B selected from the group consisting of compounds represented by the following formula (Ib) or (Ic): In formulas (Ia) to (Ic), R １ , R ２ , R ３ , R ４ , R ５ and R ６ are each independently a substituted or unsubstituted alkyl group having 2 to 9 carbon atoms, or a substituted or unsubstituted alkoxy group; R ３ and R ４ At least one of １ Or R ２ Unlike, R １ and R ２ The total number of carbon atoms in ３ and R ４ The difference between the total number of carbon atoms in R １ and R ２ The total number of carbon atoms in ５ and R ６ The difference between the total number of carbon atoms in X is 0 to 4. １ , X ２ and X ３ are each independently a counter anion.

13. The on-press development type lithographic printing plate precursor according to claim 11, wherein the infrared absorber comprises a compound represented by the following formula (X): In formula (X), Ar １１ and Ar １２ each independently represents an atomic group necessary to form a substituted or unsubstituted aromatic ring or a substituted or unsubstituted heteroaromatic ring; R １１ and R １２ are each independently a substituted or unsubstituted alkyl group; R １３ represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group; R １４ represents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group; Y each independently represents an oxygen atom, a sulfur atom, or >C(R １５ R １６ ) represents a dialkylmethylene group represented by R １５ and R １６ each independently represents a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms; A １ and A ２ each independently represents a substituted or unsubstituted alkyl group, or represents a group of atoms including 2 or 3 carbon atoms necessary to form a substituted or unsubstituted 5- or 6-membered non-aromatic carbon ring when linked together, and Za represents a counter ion that neutralizes the charge.

14. The on-press development type lithographic printing plate precursor according to claim 11, wherein the infrared absorber comprises a compound represented by the following formula 1: In formula 1, R １ and R ２ each independently represents a hydrogen atom or an alkyl group; R １ and R ２ may be linked together to form a ring, R ３ ~R ６ each independently represents a hydrogen atom or an alkyl group; R ７ and R ８ each independently represents an alkyl group or an aryl group; Y １ and Y ２ each independently represents an oxygen atom, a sulfur atom, or -NR ０ - or a dialkylmethylene group; R ０ represents a hydrogen atom, an alkyl group or an aryl group; Ar １ and Ar ２ each independently represents a group forming a benzene ring or a naphthalene ring which may have a group represented by the formula 2 described below; A １ is -NR ９ R １０ , -X １ -L １ or a group represented by formula 2 described below, R ９ and R １０ each independently represents an alkyl group, an aryl group, an alkoxycarbonyl group, or an arylsulfonyl group; X １ represents an oxygen atom or a sulfur atom, L １ is a hydrocarbon group, a heteroaryl group, or a group that is converted by heat or infrared exposure to X １ represents a group that cleaves the bond with, Za represents a counter ion that neutralizes the charge, Ar １ and Ar ２ At least one of the above has a group represented by the following formula 2: -X Formula 2 In formula 2, X is a halogen atom, -C(=O)-X ２ -R １１ , -C(=O)-NR １２ R １３ , -OC(=O)-R １４ , -CN, -SO ２ N.R. １５ R １６ or a perfluoroalkyl group; X ２ represents a single bond or an oxygen atom, R １１ and R １４ each independently represents an alkyl group or an aryl group; R １２ , R １３ , R １５ and R １６ each independently represents a hydrogen atom, an alkyl group, or an aryl group.

15. The on-press development type lithographic printing plate precursor according to claim 11, wherein the infrared absorber comprises a compound represented by formula (P1): In formula (P1), R Ｐ１ represents a group represented by the following formula (P2) or formula (P3), R Ｐ２ and R Ｐ３ each independently represents a hydrogen atom or an alkyl group; R Ｐ２ and R Ｐ３ may be linked together to form a ring, Ar Ｐ１ and Ar Ｐ２ each independently represents a benzene ring or a naphthalene ring; Y Ｐ１ and Y Ｐ２ each independently represents an oxygen atom, a sulfur atom, or -NR Ｐ０ - or a dialkylmethylene group; R Ｐ４ and R Ｐ５ each independently represents an alkyl group; R Ｐ６ ~R Ｐ９ each independently represents a hydrogen atom or an alkyl group; R Ｐ０ represents a hydrogen atom, an alkyl group, or an aryl group, and Za represents a counter ion that neutralizes the charge. In formula (P2) and formula (P3), R Ｐ１０ represents a monovalent organic group having an aryl group, R Ｐ１１ ~R Ｐ１４ and R Ｐ１７ ~R Ｐ２０ each independently represents a hydrogen atom, an alkyl group, an aryl group, a hydroxyl group, an alkoxy group, or a halogen atom; R Ｐ１５ and R Ｐ１６ each independently represents a hydrogen atom, an alkyl group, or an aryl group; R Ｐ１１ ~R Ｐ２０ At least two of these may be bonded to form a ring structure, and * represents a single bond bonded to the oxygen atom in formula (P1).

16. The on-press development type lithographic printing plate precursor according to claim 1 or 2, wherein the image recording layer contains a polymer BB having a structural unit represented by the following formula (BI): In formula (BI), R Ｂ１１ and R Ｂ１２ each independently represents a hydrogen atom or an alkyl group; R Ｂ１３ represents a hydrogen atom or a monovalent substituent; L Ｂ１１ and L Ｂ１２ each independently represents a single bond or a divalent linking group, and Rh represents a substituent containing two or more silicon atoms.

17. A method for producing a lithographic printing plate, comprising: a step of exposing the on-press development type lithographic printing plate precursor according to claim 1 or 2 in an imagewise manner; and a step of supplying at least one selected from the group consisting of printing ink and fountain solution on the printing press to remove the image recording layer in non-image areas.

18. A lithographic printing method comprising the steps of: exposing the on-press development type lithographic printing plate precursor according to claim 1 or 2 in an imagewise manner; supplying at least one selected from the group consisting of printing ink and dampening water on a printing press to remove the image recording layer in non-image areas to prepare a lithographic printing plate; and printing with the obtained lithographic printing plate.

19. A compound represented by the following formula (I): In formula (I), R represents a group having a total number of carbon atoms and oxygen atoms of 2 or more, X represents a halogen atom, an alkyl group, or an alkoxy group, and the sum of the Hammett values ​​of R and X is −0.09 to 0.

09. ＋ Li ＋ , Na ＋ , K ＋ , an iodonium cation, or an infrared absorbing dye cation.

20. The compound according to claim 19, wherein R in said formula (I) represents an alkyl group having from 2 to 4 carbon atoms, and said X is a halogen atom.

21. A compound represented by the following formula (II): In formula (II), R represents an alkyl group having 2 or more carbon atoms, or an alkoxy group having a total of 2 or more carbon atoms and oxygen atoms. ＋ represents an iodonium cation or an infrared absorbing dye cation.

22. The compound according to claim 21, wherein R in formula (II) is an alkyl group having from 2 to 4 carbon atoms in total, or an alkoxy group having from 2 to 4 carbon atoms in total and oxygen atoms in total.

23. A compound represented by the following B-7, B-25, B-26, B-29, or B-30.

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