Original plate for on-machine developing type lithographic printing plate, method for producing lithographic printing plate, and lithographic printing method

Abstract

The present invention provides an on-machine developable lithographic printing plate precursor, and a method for producing a lithographic printing plate or a lithographic printing method using the on-machine developable lithographic printing plate precursor. The on-machine developable lithographic printing plate precursor has a support and an image recording layer formed on the support. The image recording layer contains an initiator, an infrared absorber capable of supplying electrons to the initiator, and a chromogen precursor. The image recording layer can form an image by infrared laser exposure, and the change in lightness ΔL of the image recording layer before and after exposure when the image recording layer is exposed with an energy density of 110 mJ / cm<supgt;2< / supgt> of infrared laser with a wavelength of 830 nm is 3.0 or more.

Description

Technical Field

[0001] The present invention relates to an original plate for an on-machine developing type lithographic printing plate, a method for producing a lithographic printing plate, and a lithographic printing method. Background Art

[0002] Generally, a lithographic printing plate is composed of an oil-loving image portion that receives ink during the printing process and a water-loving non-image portion that receives dampening solution. Lithographic printing is a method in which, utilizing the property that water and oil-based ink repel each other, the oil-loving image portion of the lithographic printing plate is used as an ink-receiving portion, and the water-loving non-image portion is used as a dampening solution-receiving portion (non-ink-receiving portion), an adhesion difference of ink is generated on the surface of the lithographic printing plate, and after the ink is only inked on the image portion, the ink is transferred to a printing object such as paper for printing.

[0003] In order to produce this lithographic printing plate, conventionally, an original plate for a lithographic printing plate (PS plate) provided with an oil-loving photosensitive resin layer (image recording layer) on a water-loving support has been widely used. Generally, a lithographic printing plate has been obtained by plate-making through the following method: after exposing the original plate for a lithographic printing plate through a original image such as a high-contrast film, a portion of the image recording layer that becomes the image portion is left, and unnecessary image recording layer other than this is dissolved and removed by an alkaline developing solution or an organic solvent, and the surface of the water-loving support is exposed to form a non-image portion.

[0004] Moreover, due to the increasing concern for the global environment, environmental problems related to waste liquid accompanying wet processing such as developing processing have become apparent.

[0005] Regarding the above environmental problems, simplification and non-treatment of developing or plate-making have been aimed at. As one of the simple production methods, a method called "on-machine developing" has been carried out. That is, it is a method in which, after exposing the original plate for a lithographic printing plate, it is directly installed on a printing press without performing conventional developing, and unnecessary portions of the image recording layer are removed at the initial stage of the normal printing process.

[0006] In the present invention, an original plate for a lithographic printing plate that can be used for such on-machine developing is referred to as an "original plate for an on-machine developing type lithographic printing plate".

[0007] As a conventional original plate for a lithographic printing plate, for example, the original plate for a lithographic printing plate described in Patent Document 1 or Patent Document 2 can be cited.

[0008] In Patent Document 1, an original plate for a lithographic printing plate containing a color-developing compound represented by the following formula (1) in an image recording layer is described.

[0009] [Chemical Formula 1]

[0010]

[0011] In formula (1), R 1 represents a group in which the R 1 -O bond is broken by heat or infrared exposure. R 2 and R 3 each independently represent a hydrogen atom or an alkyl group, or R 2 and R 3 may be linked to each other to form a ring. Ar 1 and Ar 2 each independently represent a group forming a benzene ring or a naphthalene ring. Y 1 and Y 2 each independently represent an oxygen atom, a sulfur atom, -NR 0 -, or a dialkylmethylene group. R 4 and R 5 each independently represent an alkyl group or a group represented by the following formulas (2) to (4). R 6 to R 9 each independently represent a hydrogen atom or an alkyl group. R 0 represents a hydrogen atom, an alkyl group, or an aryl group. Za represents a counter ion for neutralizing charge. Among them, the compound represented by formula (1) has at least one group represented by formulas (2) to (4) as R 4 or R 5 or in R 1 , Ar 1 or Ar 2 .

[0012] [Chemical formula 2]

[0013]

[0014] In formulas (2) to (4), R 10 represents an alkylene group having 2 to 6 carbon atoms. W represents a single bond or an oxygen atom. n1 represents an integer of 1 to 45. R 11 represents an alkyl group having 1 to 12 carbon atoms or -C(=O)-R 14 . R 14 represents an alkyl group having 1 to 12 carbon atoms. R 12 and R 13 each independently represent a single bond or an alkylene group having 1 to 12 carbon atoms. M represents a hydrogen atom, a Na atom, a K atom, or an onium group.

[0015] In Patent Document 2, a negative lithographic printing plate precursor containing an acid developer in an image recording layer is described.

[0016] Patent Document 1: International Publication No. 2017 / 141882

[0017] Patent Document 2: U.S. Patent Application Publication No. 2009 / 0269699 Specification Summary of the Invention

[0018] Technical Problem to be Solved by the Invention

[0019] A problem to be solved by one embodiment of the present invention is to provide an on - press developable lithographic printing plate precursor having excellent visual recognition of an exposure portion.

[0020] Another problem to be solved by another embodiment of the present invention is to provide a method for producing a lithographic printing plate or a lithographic printing method using the above - mentioned on - press developable lithographic printing plate precursor.

[0021] Means for Solving the Technical Problem

[0022] The means for solving the above problems include the following means.

[0023] <1> An on - press developable lithographic printing plate precursor having a support and an image recording layer on the support, the image recording layer containing an initiator, an infrared absorber capable of supplying electrons to the initiator, and a chromogen precursor, with an energy density of 110 mJ / cm² of exposure with an infrared laser having a wavelength of 830 nm 2 The change in lightness ΔL before and after exposure of the image recording layer when the image recording layer is exposed is 3.0 or more.

[0024] <2> The on - press developable lithographic printing plate precursor according to <1>, wherein

[0025] The change in lightness ΔL is 5.0 or more.

[0026] <3> An on - press developable lithographic printing plate precursor having a support and an image recording layer on the support, the image recording layer containing an initiator, an infrared absorber, and a chromogen precursor, and the image recording layer satisfies the following formula L.

[0027] 2.0 ≤ L1 - L0 Formula L

[0028] In Formula L, L1 represents the absolute value of the difference in lightness between the unexposed portion and the exposed portion when the image recording layer is exposed with an energy density of 110 mJ / cm² of infrared laser having a wavelength of 830 nm 2 L0 represents the absolute value of the difference in lightness between the unexposed portion and the exposed portion when a layer identical to the image recording layer except for the chromogen precursor is exposed with an energy density of 110 mJ / cm² of infrared laser having a wavelength of 830 nm 2 The absolute value of the difference in lightness between the unexposed portion and the exposed portion when a layer identical to the image recording layer except for the chromogen precursor is exposed.

[0029] <4> The on - press developable lithographic printing plate precursor according to any one of <1> to <3>, wherein

[0030] The molar extinction coefficient ε of the chromogen formed from the above chromogen precursor is 35,000 or more.

[0031] <5> The original plate for on-machine developing lithographic printing plate according to any one of <1> to <4>, wherein

[0032] The ring-opening rate of the above chromogen precursor calculated by the following formula is 40 mol% to 99 mol%.

[0033] Ring-opening rate = Molar extinction coefficient when 1 molar equivalent of acid is added to the above chromogen precursor / Molar extinction coefficient ε of the above chromogen precursor × 100

[0034] <6> The original plate for on-machine developing lithographic printing plate according to any one of <1> to <5>, wherein

[0035] The maximum absorption wavelength of the chromogen formed from the above chromogen precursor in the wavelength range of 380 nm to 750 nm is 500 nm to 650 nm.

[0036] <7> The original plate for on-machine developing lithographic printing plate according to any one of <1> to <6>, wherein

[0037] The above chromogen precursor has two or more electron-donating groups directly bonded to the aromatic ring.

[0038] <8> The original plate for on-machine developing lithographic printing plate according to any one of <1> to <7>, wherein

[0039] The above chromogen precursor has a xanthene structure.

[0040] <9> The original plate for on-machine developing lithographic printing plate according to any one of claims 1 to 8, wherein

[0041] The above chromogen precursor contains a compound represented by the following formula (Z-1) or formula (Z-2).

[0042] [Chemical formula 3]

[0043]

[0044] In formula (Z-1) and formula (Z-2), EDG each independently represents an electron-donating group, X represents O or NR, R represents a hydrogen atom, an alkyl group, an aryl group or a heteroaryl group, Y1 and Y2 each independently represent CH or N, and Ra1 represents a hydrogen atom, an alkyl group or an alkoxy group.

[0045] <10> The original plate for on-machine developing lithographic printing plate according to any one of <1> to <9>, wherein

[0046] The above-described chromogen precursor contains a compound represented by the following formula (Z-3) or formula (Z-4).

[0047] [Chemical formula 4]

[0048]

[0049] In formula (Z-3) and formula (Z-4), Ra1 represents a hydrogen atom, an alkyl group, or an alkoxy group, Rb1 to Rb4 each independently represent a hydrogen atom, an alkyl group, or an aryl group, Rb1 and Rb2, and Rb3 and Rb4 may form a ring, and Y1 and Y2 each independently represent CH or N.

[0050] <11> The original plate for on-machine developable lithographic printing plate according to any one of <1> to <10>, wherein

[0051] The hydrogen abstraction enthalpy of all hydrogen atoms present in the molecule of the above-described chromogen precursor is -6.5 kcal / mol or more.

[0052] <12> The original plate for on-machine developable lithographic printing plate according to any one of <1> to <11>, wherein

[0053] The above-described chromogen precursor does not have a structure in which a hydrogen atom is directly bonded to a nitrogen atom.

[0054] <13> The original plate for on-machine developable lithographic printing plate according to any one of <1> to <12>, wherein

[0055] The above-described chromogen precursor is an acid developer.

[0056] <14> The original plate for on-machine developable lithographic printing plate according to any one of <1> to <13>, wherein

[0057] The above-described image recording layer contains at least one compound selected from the group consisting of onium salt compounds and borate compounds.

[0058] <15> The original plate for on-machine developable lithographic printing plate according to any one of <1> to <14>, wherein

[0059] The above-described image recording layer contains a borate compound,

[0060] The HOMO of the above-described infrared absorber - the HOMO value of the above-described borate compound is 0.70 eV or less.

[0061] <16> The original plate for on-machine developable lithographic printing plate according to any one of <1> to <15>, wherein

[0062] The above-described image recording layer further contains a polymerizable compound.

[0063] <17> The original printing plate for on-machine development lithography according to <16>, wherein,

[0064] The above-mentioned polymerizable compound contains a polymerizable compound having 7 or more functional groups.

[0065] <18> The original printing plate for on-machine development lithography according to <16> or <17>, wherein,

[0066] The above-mentioned polymerizable compound contains a polymerizable compound having 10 or more functional groups.

[0067] <19> The original printing plate for on-machine development lithography according to any one of <16> to <18>, wherein,

[0068] The above-mentioned polymerizable compound contains a compound having an ethylenically unsaturated bond value of 5.0 mmol / g or more.

[0069] <20> The original printing plate for on-machine development lithography according to <19>, wherein,

[0070] The compound having an ethylenically unsaturated bond value of 5.0 mmol / g or more is a compound represented by the following formula (I).

[0071] Formula (I): X-(Y) n

[0072] In formula (I), X represents an n-valent organic group having a hydrogen bonding group, Y represents a monovalent group having two or more ethylenically unsaturated groups, n represents an integer of 2 or more, and the molecular weight of X / (the molecular weight of Y × n) is 1 or less.

[0073] <21> The original printing plate for on-machine development lithography according to <19> or <20>, wherein,

[0074] The compound having an ethylenically unsaturated bond value of 5.0 mmol / g or more has at least one structure selected from the group consisting of an adduct structure, a biuret structure, and an isocyanurate structure.

[0075] <22> The original printing plate for on-machine development lithography according to any one of <16> to <21>, wherein,

[0076] The above-mentioned polymerizable compound contains a compound having one or two ethylenically unsaturated groups.

[0077] <23> The original printing plate for on-machine development lithography according to any one of <1> to <22>, wherein,

[0078] The above-mentioned image recording layer further contains addition-polymerizable resin particles having a dispersibility group, and the dispersibility group contains a group represented by the following formula Z.

[0079] *-Q-W-Y type Z

[0080] 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, any one of W and Y has a hydrophilic structure, and * represents a bonding site with other structures.

[0081] <24> The original printing plate for on-machine development according to any one of <1> to <23>, wherein,

[0082] The above initiator contains an electron-accepting polymerization initiator,

[0083] The above electron-accepting polymerization initiator contains a compound represented by the following formula (II).

[0084] [Chemical formula 5]

[0085]

[0086] In formula (II), X represents a halogen atom, and R 3 represents an aryl group.

[0087] <25> The original printing plate for on-machine development according to any one of <1> to <24>, wherein,

[0088] The above image recording layer further contains polyvinyl acetal as an adhesive polymer.

[0089] <26> The original printing plate for on-machine development according to any one of <1> to <25>, wherein,

[0090] The above image recording layer further contains a copolymer containing a fluoroaliphatic group.

[0091] <27> The original printing plate for on-machine development according to <26>, wherein,

[0092] The above copolymer containing a fluoroaliphatic group has a structural unit formed from a compound represented by any one of the following formula (F1) and the following formula (F2).

[0093] [Chemical formula 6]

[0094]

[0095] In formulas (F1) and (F2), R F1 each independently represents a hydrogen atom or a methyl group, and X each independently represents an oxygen atom, a sulfur atom, or -N(R F2)-, where m represents an integer from 1 to 6, n represents an integer from 1 to 10, l represents an integer from 0 to 10, and R F2 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

[0096] <28> The original plate for an on-machine developable lithographic printing plate according to <27>, wherein

[0097] the copolymer containing a fluorinated aliphatic group further has a structural unit formed of at least one compound selected from poly(oxyalkylene) acrylate and poly(oxyalkylene) methacrylate.

[0098] <29> The original plate for an on-machine developable lithographic printing plate according to any one of <1> to <28>, wherein

[0099] an overcoat layer is further provided on the above image recording layer.

[0100] <30> The original plate for an on-machine developable lithographic printing plate according to <29>, wherein

[0101] the above overcoat layer contains a hydrophobic polymer.

[0102] <31> The original plate for an on-machine developable lithographic printing plate according to <29> or <30>, wherein

[0103] the above overcoat layer contains a chromogen precursor.

[0104] <32> The original plate for an on-machine developable lithographic printing plate according to <31>, wherein

[0105] the chromogen precursor in the above overcoat layer is an infrared absorber.

[0106] <33> The original plate for an on-machine developable lithographic printing plate according to <31> or <32>, wherein

[0107] the chromogen precursor in the above overcoat layer contains a decomposable compound that decomposes upon infrared exposure.

[0108] <34> The original plate for an on-machine developable lithographic printing plate according to any one of <1> to <33>, wherein

[0109] the above support has an aluminum plate and an anodic oxide film of aluminum disposed on the above aluminum plate, the anodic oxide film is located closer to the above image recording layer side than the above aluminum plate, the anodic oxide film has micropores extending along the depth direction from the surface on the above image recording layer side, the average diameter of the micropores on the surface of the anodic oxide film exceeds 10 nm and is 100 nm or less, and the L of the surface of the anodic oxide film on the above image recording layer side * a * b* Lightness L in the color system * has a value of 70 to 100.

[0110] <35> The on-machine developable lithographic printing plate precursor according to <34>, wherein

[0111] the micropores are composed of a large-diameter pore portion and a small-diameter pore portion, the large-diameter pore portion extends from the surface of the anodic oxide film to a position at a depth of 10 nm to 1,000 nm, the small-diameter pore portion communicates with the bottom of the large-diameter pore portion and extends from the communication position to a position at a depth of 20 nm to 2,000 nm, the average diameter of the large-diameter pore portion on the surface of the anodic oxide film is 15 nm to 100 nm, and the average diameter of the small-diameter pore portion at the communication position is 13 nm or less.

[0112] <36> A method for producing a lithographic printing plate, comprising: a step of exposing the on-machine developable lithographic printing plate precursor according to any one of <1> to <35> into an image shape; and a step of supplying at least one selected from the group consisting of printing ink and dampening solution on a printing press to remove the image recording layer of the non-image portion.

[0113] <37> A lithographic printing method, comprising: a step of exposing the on-machine developable lithographic printing plate precursor according to any one of <1> to <35> into an image shape; a step of supplying at least one selected from the group consisting of printing ink and dampening solution to remove the image recording layer of the non-image portion on a printing press to produce a lithographic printing plate; and a step of performing printing using the obtained lithographic printing plate.

[0114] <38> A method for producing a lithographic printing plate, comprising: a step of exposing the on-machine developable lithographic printing plate precursor into an image shape by infrared laser; and a step of supplying at least one selected from the group consisting of printing ink and dampening solution on a printing press to remove the image recording layer of the non-image portion, the on-machine developable lithographic printing plate precursor having a support and an image recording layer on the support, the image recording layer containing an initiator, an infrared absorber capable of supplying electrons to the initiator, and a chromogen precursor, with an energy density of 110 mJ / cm of infrared laser exposure at a wavelength of 830 nm 2 The change in lightness ΔL before and after exposure of the image recording layer when exposing the image recording layer is 3.0 or more.

[0115] <39>A method for producing a lithographic printing plate includes: a step of exposing an on-press developable lithographic printing plate original to an image by infrared laser; and a step of removing the image recording layer of the non-image portion by supplying at least one selected from the group consisting of printing ink and dampening solution on a printing press. The on-press developable lithographic printing plate original has a support and an image recording layer on the support. The image recording layer contains an initiator, an infrared absorber, and a chromogen precursor, and the image recording layer satisfies the following formula L.

[0116] 2.0 ≤ L1 - L0 Formula L

[0117] In Formula L, L1 represents the absolute value of the difference in lightness between the unexposed portion and the exposed portion when the image recording layer is exposed with an infrared laser having a wavelength of 830 nm and an energy density of 110 mJ / cm 2 2, and L0 represents the absolute value of the difference in lightness between the unexposed portion and the exposed portion when a layer identical to the image recording layer except for the chromogen precursor is exposed with an infrared laser having a wavelength of 830 nm and an energy density of 110 mJ / cm 2 2.

[0118] Advantages of the Invention

[0119] According to one embodiment of the present invention, an on-press developable lithographic printing plate original with excellent visual recognition of the exposed portion can be provided.

[0120] Moreover, according to another embodiment of the present invention, a method for producing a lithographic printing plate or a lithographic printing method using the above on-press developable lithographic printing plate original can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0121] Figure 1 is a schematic cross-sectional view of one embodiment of the lithographic printing plate original of the present invention.

[0122] Figure 2A is a schematic cross-sectional view of one embodiment of an aluminum support with an anodic oxide film.

[0123] Figure 2B is an enlarged Figure 2A schematic cross-sectional view of one micropore in

[0124] Figure 3A is a schematic cross-sectional view of another embodiment of an aluminum support with an anodic oxide film.

[0125] Figure 3B is a schematic cross-sectional view of another embodiment of an aluminum support with an anodic oxide film.

[0126] Figure 4AIt is a schematic cross-sectional view of another embodiment of an aluminum support having an anodic oxide film.

[0127] Figure 4B It is a schematic cross-sectional view of another embodiment of an aluminum support having an anodic oxide film.

[0128] Figure 5 It is a schematic cross-sectional view of an aluminum support having anodic oxide films shown in the order of processes from the first anodizing process to the second anodizing process.

[0129] Figure 6 It is a graph showing an example of an alternating waveform current waveform used in the electrochemical roughening treatment in the manufacturing method of an aluminum support having an anodic oxide film.

[0130] Figure 7 It is a side view showing an example of a radial type cell in the electrochemical roughening treatment using alternating current in the manufacturing method of an aluminum support having an anodic oxide film.

[0131] Figure 8 It is a side view showing the concept of the process of a brushing abrasive plate used in the mechanical roughening treatment in the manufacturing method of an aluminum support having an anodic oxide film.

[0132] Figure 9 It is a schematic diagram of an anodizing apparatus used in the anodizing treatment in the manufacturing method of an aluminum support having an anodic oxide film. Detailed Embodiments

[0133] Hereinafter, the content of the present invention will be described in detail. The description of the constituent elements described below is based on representative embodiments of the present invention, but the present invention is not limited to such embodiments.

[0134] In addition, in this specification, “~” indicating a numerical range is used in the meaning of including the numerical values described before and after it as the lower limit value and the upper limit value.

[0135] Moreover, in the notation of groups (atomic groups) in this specification, the notation without indicating substitution or unsubstitution includes not only groups without substituents but also groups with substituents. For example, “alkyl” includes not only alkyls without substituents (unsubstituted alkyls) but also alkyls with substituents (substituted alkyls).

[0136] In this specification, “(meth)acrylic acid” is a term used to include both acrylic acid and methacrylic acid, and “(meth)acryloyl” is a term used to include both acryloyl and methacryloyl.

[0137] Moreover, the term "process" in this specification includes not only independent processes, but also those that, even if not clearly distinguishable from other processes, are included in this term as long as the intended purpose of the process can be achieved. Also, in the present invention, the definitions of "mass %" and "weight %" are the same, and the definitions of "parts by mass" and "parts by weight" are the same.

[0138] Unless otherwise specified, each component in the composition or each structural unit in the polymer in the present invention may contain one kind alone or two or more kinds may be used simultaneously.

[0139] Furthermore, in the present invention, regarding the amounts of each component in the composition or each structural unit in the polymer, in the case where there are multiple substances or structural units corresponding to each component in the composition or each structural unit in the polymer, unless otherwise specified, it refers to the total amount of the corresponding multiple substances present in the composition or the corresponding multiple structural units present in the polymer.

[0140] Moreover, in the present invention, the combination of two or more preferred modes is a more preferred mode.

[0141] Unless otherwise specified, the weight-average molecular weight (Mw) and number-average molecular weight (Mn) in the present invention are the molecular weights in terms of polystyrene measured by a gel permeation chromatography (GPC) analyzer using columns of TSKgel GMHxL, TSKgel G4000HxL, and TSKgel G2000HxL (all are trade names manufactured by TOSOH CORPORATION), detected by a differential refractometer with the solvent THF (tetrahydrofuran).

[0142] In the present invention, the term "original planographic printing plate" includes not only the original planographic printing plate but also the original waste plate. And the term "planographic printing plate" includes not only the planographic printing plate produced by subjecting the original planographic printing plate to operations such as exposure and development as needed, but also the waste plate. In the case of the original waste plate, the operations of exposure and development are not necessarily required. In addition, the waste plate refers to, for example, in color newspaper printing, when a part of the layout is printed in monochrome or two colors, the original planographic printing plate used for mounting on an unused printing plate cylinder.

[0143] Moreover, in the present invention, "*" in the chemical structural formula indicates the bonding position with other structures.

[0144] Hereinafter, the present invention will be described in detail.

[0145] (On-machine developing type original planographic printing plate)

[0146] The first embodiment of the on-machine developable lithographic printing plate precursor (also simply referred to as "lithographic printing plate precursor") according to the present invention has a support and an image recording layer formed on the support. The image recording layer contains an initiator, an infrared absorber capable of supplying electrons to the initiator, and a chromogen precursor, and the energy density of exposure with an infrared laser having a wavelength of 830 nm is 110 mJ / cm 2 When the image recording layer is exposed, the change in lightness ΔL before and after the exposure of the image recording layer is 3.0 or more.

[0147] The second embodiment of the on-machine developable lithographic printing plate precursor according to the present invention has a support and an image recording layer formed on the support. The image recording layer contains an initiator, an infrared absorber, and a chromogen precursor, and the image recording layer satisfies the following formula L.

[0148] 2.0 ≤ L1 - L0 Formula L

[0149] In Formula L, L1 represents the absolute value of the difference in lightness between the unexposed portion and the exposed portion of the image recording layer, and L0 represents the absolute value of the difference in lightness between the unexposed portion and the exposed portion of a layer that is the same as the image recording layer except for the chromogen precursor.

[0150] In addition, in this specification, unless otherwise specified, when simply referred to as "the on-machine developable lithographic printing plate precursor according to the present invention" or "the lithographic printing plate precursor according to the present invention", both the first embodiment and the second embodiment are described. And unless otherwise specified, when simply referred to as "image recording layer" or the like, all image recording layers and the like of the first embodiment and the second embodiment are described.

[0151] Moreover, the on-machine developable lithographic printing plate precursor according to the present invention is preferably a negative-type lithographic printing plate precursor.

[0152] In the lithographic printing plate precursors described in the conventional Patent Document 1 or Patent Document 2, the visual recognition of the exposed portion is insufficient.

[0153] As a result of intensive studies by the present inventors, it has been found that in the obtained lithographic printing plate, a lithographic printing plate precursor with excellent visual recognition (hereinafter, also simply referred to as "visual recognition") of the exposed portion can be provided.

[0154] In addition, in the on-machine developable lithographic printing plate precursor according to the present invention, although the detailed mechanism is not clear, the stability over time and the UV printing durability are also excellent.

[0155] In a lithographic printing plate, a case where the number of printable plates is large is referred to as "excellent printing durability". Hereinafter, the printing durability when using UV ink is also referred to as "UV printing durability".

[0156] Hereinafter, the detailed content of each constituent element in the original lithographic printing plate according to the present invention will be described.

[0157] <Image recording layer>

[0158] The original lithographic printing plate according to the present invention has an image recording layer formed on a support.

[0159] The first embodiment of the original on-machine-developable lithographic printing plate according to the present invention includes an initiator, an infrared absorber capable of supplying electrons to the initiator, and a chromogen precursor, and preferably includes a polymerizable compound, a polymerization initiator, an infrared absorber capable of supplying electrons to the polymerization initiator, and a chromogen precursor.

[0160] The second embodiment of the original on-machine-developable lithographic printing plate according to the present invention includes an initiator, an infrared absorber, and a chromogen precursor, preferably includes an initiator, an infrared absorber capable of supplying electrons to the initiator, and a chromogen precursor, and more preferably includes a polymerizable compound, a polymerization initiator, an infrared absorber capable of supplying electrons to the polymerization initiator, and a chromogen precursor.

[0161] The image recording layer used in the present invention is preferably a negative-type image recording layer, and more preferably a water-soluble or water-dispersible negative-type image recording layer.

[0162] Regarding the original lithographic printing plate according to the present invention, from the viewpoint of on-machine developability, it is preferable that the unexposed portion of the image recording layer can be removed by at least one of dampening solution and printing ink.

[0163] In the first embodiment of the original on-machine-developable lithographic printing plate according to the present invention, the above image recording layer can be exposed with infrared laser to form an image, and the energy density of exposure with an infrared laser having a wavelength of 830 nm is 110 mJ / cm 2 The change in lightness ΔL before and after the exposure of the image recording layer when the image recording layer is exposed is 3.0 or more. If it is within the above range, visual recognition, UV printing durability, and stability over time are excellent.

[0164] In the second embodiment of the original on-machine-developable lithographic printing plate according to the present invention, from the viewpoints of visual recognition, UV printing durability, and stability over time, it is preferable that the above image recording layer can be exposed with infrared laser to form an image, and, the energy density of exposure with an infrared laser having a wavelength of 830 nm is 110 mJ / cm 2When exposing the above-described image recording layer, the change in lightness ΔL before and after exposure of the above-described image recording layer is preferably 3.0 or more.

[0165] In the first embodiment of the on-machine developable lithographic printing plate precursor of the present invention, from the viewpoints of visual recognition, UV printing durability, and stability over time, the change in lightness ΔL is preferably 5.0 or more, more preferably 8.0 or more, and particularly preferably 10.0 to 20.0.

[0166] In the second embodiment of the on-machine developable lithographic printing plate precursor of the present invention, from the viewpoints of visual recognition, UV printing durability, and stability over time, the change in lightness ΔL is more preferably 5.0 or more, further preferably 8.0 or more, and particularly preferably 10.0 to 20.0.

[0167] The energy density of exposure with an infrared laser having a wavelength of 830 nm is 110 mJ / cm 2 The measurement of the change in lightness ΔL before and after exposure of the above-described image recording layer when exposing the above-described image recording layer is carried out by the following method.

[0168] Using a Luxel PLATESETTER T-9800 manufactured by FUJIFILM Graphic Systems Co., Ltd. equipped with an infrared semiconductor laser having a wavelength of 830 nm, under the conditions of an output of 99.5%, an outer drum rotation speed of 220 rpm, and a resolution of 2,400 dpi (dots per inch, 1 inch = 25.4 mm) (energy density is 110 mJ / cm 2 ), the lithographic printing plate precursor is exposed. Regarding the exposure, it is carried out in an environment of 25°C and 50% RH.

[0169] Measure the change in lightness of the lithographic printing plate precursor before and after exposure. In the measurement, an eXact spectral colorimeter manufactured by X-Rite Inc. is used. Using the L * a * b * value (lightness) in the L * *a* * *b* * value system, the absolute value of the difference between the L

[0170] -type L-

[0171] The image recording layer in the second embodiment of the on-machine developable lithographic printing plate precursor of the present invention satisfies the following formula L. If it is the above-described method, the visual recognition, UV printing durability, and stability over time are excellent.

[0172] From the viewpoints of visual recognition, durability of UV printing, and stability over time, the image recording layer in the first embodiment of the original lithographic printing plate for on-machine development according to the present invention preferably satisfies the following formula L.

[0173] 2.0 ≤ L1 - L0 Formula L

[0174] In Formula L, L1 represents the absolute value of the difference in lightness between the unexposed portion and the exposed portion when the image recording layer is exposed with an infrared laser having a wavelength of 830 nm at an energy density of 110 mJ / cm 2 and L0 represents the absolute value of the difference in lightness between the unexposed portion and the exposed portion when a layer identical to the image recording layer except for the above-mentioned chromogen precursor is exposed with an infrared laser having a wavelength of 830 nm at an energy density of 110 mJ / cm 2 and the same layer as the image recording layer except for the above-mentioned chromogen precursor is exposed.

[0175] Regarding the measurement of the values of L1 and L0, they are measured by the following method.

[0176] Using Trendsetter3244VX manufactured by Creo Inc. equipped with a water-cooled 40W infrared semiconductor laser having a wavelength of 830 nm, under the conditions of an output of 11.5W, an outer drum rotation speed of 220 rpm, and a resolution of 2,400 dpi (dots per inch, 1 inch = 25.4 mm), and at an energy density of 110 mJ / cm 2 the original lithographic printing plate is exposed. Regarding the exposure, it is carried out in an environment of 25°C and 50% RH.

[0177] Measure the following L in the unexposed portion and the exposed portion of the original lithographic printing plate after exposure * . Regarding the measurement, it is carried out by the SCE (removing specular reflected light) method using a spectrocolorimeter CM2600d manufactured by Konica Minolta, Inc. and operation software CM-S100W. Using L * a * b * value (lightness) in the L * colorimetric system, the absolute value of the difference in lightness between the unexposed portion and the exposed portion of the image recording layer after exposure is taken as L1.

[0178] Similarly, prepare a plate without a chromogen precursor, measure it in the same manner as above, and take the absolute value of the difference in lightness between the unexposed portion and the exposed portion of the image recording layer after exposure as L0.

[0179] From the viewpoints of visual recognition, UV printing durability, and stability over time, the image recording layer in the second embodiment of the original plate for on-machine developable lithographic printing plates according to the present invention preferably satisfies the following formula L1, more preferably satisfies the following formula L2, and particularly preferably satisfies the following formula L3.

[0180] From the viewpoints of visual recognition, UV printing durability, and stability over time, the image recording layer in the first embodiment of the original plate for on-machine developable lithographic printing plates according to the present invention more preferably satisfies the following formula L1, further preferably satisfies the following formula L2, and particularly preferably satisfies the following formula L3.

[0181] 3.0 ≤ L1 - L0 Formula L1

[0182] 5.0 ≤ L1 - L0 Formula L2

[0183] 8.0 ≤ L1 - L0 ≤ 20.0 Formula L3

[0184] From the viewpoints of visual recognition, UV printing durability, and stability over time, the value of L1 in the image recording layer of the original plate for on-machine developable lithographic printing plates according to the present invention is preferably 5.0 or more, more preferably 8.0 or more, and particularly preferably 10.0 to 20.0.

[0185] Hereinafter, the details of each component contained in the image recording layer will be described.

[0186] - Chromogen precursor -

[0187] The above image recording layer contains a chromogen precursor.

[0188] As the above chromogen precursor, from the viewpoint of color development, an acid color former is preferably contained. And, as the chromogen precursor, from the viewpoint of color development, a colorless compound is preferably contained.

[0189] The "chromogen precursor" used in the present invention refers to a compound having the property of developing color by stimuli such as light and acid and changing the color of the image recording layer, and the "acid color former" refers to a compound having the property of developing color by heating in a state of receiving an electron-accepting compound (e.g., a proton such as an acid) and changing the color of the image recording layer. As the acid color former, it particularly has partial skeletons such as lactone, lactam, sultone, spiropyran, ester, and amide, and is preferably a colorless compound in which these partial skeletons rapidly ring-open or cleave when in contact with an electron-accepting compound.

[0190] From the viewpoint of the durability of UV printing, the hydrogen abstraction enthalpy of all hydrogen atoms present in the molecule of the above-described chromogen precursor is preferably -6.5 kcal / mol or more, more preferably -4.0 kcal / mol or more, still more preferably -2.0 kcal / mol or more, and particularly preferably -2.0 kcal / mol to 50 kcal / mol.

[0191] The larger the value of the above hydrogen abstraction enthalpy, the more the abstraction of hydrogen atoms from the above chromogen precursor by polymerization initiation species such as free radicals is suppressed, and the polymerization reaction occurs for a long time. Therefore, the curability is excellent, and the printing durability, particularly the UV printing durability, is more excellent.

[0192] The hydrogen abstraction enthalpy of all hydrogen atoms present in the molecule of the chromogen precursor in the present invention is calculated by the following method.

[0193] The calculation program uses Gaussian 16, the calculation level is set to the density functional method (B3LYP / 6-31+G**), the solvent effect is set to the SCRF method (solvent: methanol), and for the reaction with the growing free radical caused by hydrogen abstraction, the enthalpies of the reactants and products are calculated respectively, and the difference between the two is taken to perform the reaction enthalpy calculation.

[0194] More specifically, it is implemented in the following manner. For the growing free radical, LeucoDye-H, hydrogenated growing free radical, and LeucoDye-radical in the following chemical reaction formula, modeling is performed using the Gaussian PrePost software GaussView6. The specification of the calculation conditions is set to #p opt b3lyp / 6-31+g(d,p) scrf=(solvent=methanol, in the case of free radicals, the charge is set to 0 and the multiplicity is set to 2, and in the case other than free radicals, the charge is set to 0 and the multiplicity is set to 1. The specification of #p is the specification of detailed log output and can be omitted.

[0195] Based on the energy (unit: hartree) of the structure that has been calculated and optimized, the formation enthalpy of the reactants (the sum of the energies of the growing free radical and LeucoDye-H) and the formation enthalpy of the products (the sum of the energies of the hydrogenated growing free radical and LeucoDye-radical) are obtained, and the value obtained by subtracting the formation enthalpy of the reactants from the formation enthalpy of the products is used as the hydrogen abstraction enthalpy. The unit conversion is 1 hartree = 627.51 kcal / mol.

[0196] [Chemical formula 7]

[0197]

[0198] For example, the hydrogen abstraction enthalpies of the hydrogen atoms in the following compounds are as follows.

[0199] [Chemical formula 8]

[0200]

[0201] From the viewpoint of UV printing durability, the above-mentioned chromogenic precursor preferably does not have a structure in which a hydrogen atom is directly bonded to a nitrogen atom.

[0202] A structure in which a hydrogen atom is directly bonded to a nitrogen atom (N-H structure) is a structure in which a hydrogen abstraction reaction caused by free radicals or the like easily occurs. If the compound does not have such a structure, the hydrogen atom can be inhibited from being abstracted from the above-mentioned chromogenic precursor, and a polymerization reaction can occur for a long time. Therefore, the curability is excellent, and the printing durability, especially the UV printing durability, is more excellent.

[0203] Among them, from the viewpoint of color development, the color former used in the present invention is preferably at least one compound selected from the group consisting of spiropyran compounds, spirooxazine compounds, spiro lactone compounds, and spiro lactam compounds.

[0204] From the viewpoint of visibility, the hue of the pigment after color development is preferably green, blue, or black.

[0205] And, from the viewpoints of color development and visual recognition of the exposed part, the above-mentioned acid color former is preferably a leuco dye.

[0206] As the above-mentioned leuco dye, as long as it is a pigment having a colorless structure, there is no particular limitation, but it preferably has a spiro structure, and more preferably has a spiro lactone ring structure.

[0207] And, as the above-mentioned leuco dye, from the viewpoints of color development and visual recognition of the exposed part, a leuco dye having a phthalide structure or a fluoran structure is preferred.

[0208] From the viewpoints of visual recognition, UV printing durability, and stability over time, the above-mentioned chromogenic precursor preferably has two or more electron-donating groups directly bonded to an aromatic ring.

[0209] As the above-mentioned electron-donating group, from the viewpoints of color development and visual recognition of the exposed part, an amino group, an alkylamino group, an arylamino group, a dialkylamino group, a monoalkylmonoarylamino group, a diarylamino group, an alkoxy group, an aryloxy group, or an alkyl group is preferred, more preferably an amino group, an alkylamino group, an arylamino group, a dialkylamino group, a monoalkylmonoarylamino group, a diarylamino group, an alkoxy group, or an aryloxy group, further preferably a monoalkylmonoarylamino group or a diarylamino group, and particularly preferably a monoalkylmonoarylamino group.

[0210] Moreover, as the above-mentioned chromogen precursor, from the viewpoints of visual recognition, UV printing durability, and stability over time, it preferably has a xanthene structure.

[0211] Furthermore, as the above-mentioned chromogen precursor, from the viewpoints of visual recognition, UV printing durability, and stability over time, it preferably contains a compound represented by the following formula (Z-1) or formula (Z-2), and more preferably contains a compound represented by the following formula (Z-1).

[0212] [Chemical formula 9]

[0213]

[0214] In formula (Z-1) and formula (Z-2), EDG each independently represents an electron-donating group, X represents O or NR, R represents a hydrogen atom, an alkyl group, an aryl group, or a heteroaryl group, Y1 and Y2 each independently represent CH or N, and Ra1 represents a hydrogen atom, an alkyl group, or an alkoxy group.

[0215] As the electron-donating group in EDG of formula (Z-1) and formula (Z-2), from the viewpoints of color development and visual recognition of the exposed part, it is preferably an amino group, an alkylamino group, an arylamino group, a dialkylamino group, a monoalkylmonoarylamino group, a diarylamino group, an alkoxy group, an aryloxy group, or an alkyl group, more preferably an amino group, an alkylamino group, an arylamino group, a dialkylamino group, a monoalkylmonoarylamino group, a diarylamino group, an alkoxy group, or an aryloxy group, further preferably a monoalkylmonoarylamino group or a diarylamino group, and particularly preferably a monoalkylmonoarylamino group.

[0216] Furthermore, as the above-mentioned chromogen precursor, from the viewpoints of visual recognition, UV printing durability, and stability over time, it is more preferably to contain a compound represented by the following formula (Z-3) or formula (Z-4), and particularly preferably to contain a compound represented by the following formula (Z-3).

[0217] [Chemical formula 10]

[0218]

[0219] In formula (Z-3) and formula (Z-4), Ra1 represents a hydrogen atom, an alkyl group, or an alkoxy group, Rb1 to Rb4 each independently represent a hydrogen atom, an alkyl group, or an aryl group, Rb1 and Rb2, Rb3 and Rb4 may form a ring, and Y1 and Y2 each independently represent CH or N.

[0220] From the viewpoints of visual recognition, UV printing durability, and stability over time, Rb1 and Rb4 in formula (Z-3) and formula (Z-4) are each independently preferably an alkyl group or an aryl group, and more preferably an aryl group.

[0221] From the viewpoints of visual recognition, UV printing durability, and stability over time, Rb2 and Rb3 in formula (Z-3) and formula (Z-4) are each independently preferably an alkyl group or an aryl group, more preferably an alkyl group.

[0222] From the viewpoints of visual recognition, UV printing durability, and stability over time, Rb1 and Rb4 in formula (Z-3) and formula (Z-4) are each independently preferably a hydrogen atom or an alkoxy group, more preferably a hydrogen atom.

[0223] Further, in formula (Z-3) and formula (Z-4), from the viewpoints of color development property and visual recognition of the exposure part, it is preferred that X1 to X4 are hydrogen atoms and Y1 and Y2 are C.

[0224] The alkyl group in formula (Z-1) to formula (Z-4) may be linear, may have a branched chain, or may have a ring structure.

[0225] Moreover, the number of carbon atoms of the alkyl group in formula (Z-1) to formula (Z-4) is preferably 1 to 20, more preferably 1 to 8, still more preferably 1 to 4, and particularly preferably 1 or 2.

[0226] The number of carbon atoms of the aryl group in formula (Z-1) to formula (Z-4) is preferably 6 to 20, more preferably 6 to 10, and particularly preferably 6 to 8.

[0227] In addition, each group such as the alkyl group and the aryl group in formula (Z-1) to 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 hydroxyl group, an alkoxy group, an aryloxy group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a cyano group, etc. Further, these substituents may be further substituted by these substituents.

[0228] From the viewpoint of visual recognition, the molar extinction coefficient ε of the chromogen generated from the above chromogen precursor is preferably 35,000 or more, more preferably 35,000 or more and 200,000 or less, and particularly preferably 50,000 or more and 150,000 or less.

[0229] The molar extinction coefficient ε of the chromogen generated from the chromogen precursor in the present invention is measured by the following method.

[0230] Precisely weigh 0.04 mmol of the measured chromogen precursor into a 100 mL volumetric flask.

[0231] Add about 90 mL of acetic acid. After visually confirming that the measurement sample is completely dissolved, make up the volume to 100 mL with acetic acid to prepare a pigment solution A.

[0232] After adding about 80 mL of acetic acid to another 100-mL volumetric flask, 5 mL of ion-exchanged water and 5 mL of the above-mentioned pigment solution A were respectively added using a 5-mL volumetric pipette, and gently shaken and mixed.

[0233] After visually confirming that no chromogen precursors were precipitated, it was made up to 100 mL with acetic acid to prepare pigment solution B. In pigment solution B, the concentration of chromogen precursors was 0.02 mmol / L.

[0234] Pigment solution B was filled into the measurement unit (quartz glass, optical path width: 10 mm), and measurement was carried out using an ultraviolet-visible spectrophotometer (manufactured by SHIMADZU CORPORATION, UV-1800).

[0235] The blank medium was set as a water:acetic acid = 5:95 solution.

[0236] From the obtained spectrum, the absorption maximum wavelength in the visible light region (380 nm to 750 nm) was read, and the molar absorption coefficient ε was calculated based on the absorbance at this wavelength.

[0237] Regarding the above-mentioned chromogen precursors, from the viewpoint of visual recognition, the ring-opening rate calculated by the following formula is preferably 15% or more and 100% or less, more preferably 40% or more and 99% or less, further preferably 60% or more and 99% or less, particularly preferably 75% or more and 99% or less, and most preferably 85% or more and 99% or less.

[0238] Ring-opening rate = molar absorption coefficient when 1 molar equivalent of acid is added to the chromogen precursor / molar absorption coefficient ε of the chromogen precursor × 100

[0239] From the viewpoint of visual recognition, the maximum absorption wavelength λmax in the visible light region (380 nm to 750 nm) of the chromogen generated from the above-mentioned chromogen precursor is preferably 500 nm to 650 nm, more preferably 520 nm to 600 nm, further preferably 530 nm to 580 nm, particularly preferably 540 nm to 570 nm.

[0240] The above-mentioned ring-opening rate and the above-mentioned λmax in the present invention are measured by the following method.

[0241] - Preparation of pigment solution C -

[0242] 0.1 mmol of the chromogen precursor was accurately weighed into a 50-mL volumetric flask.

[0243] About 40 mL of acetonitrile was added. After visually confirming that the measurement sample was completely dissolved, it was made up to 50 mL with acetonitrile to prepare pigment solution C.

[0244] - Preparation of Acid Solution D -

[0245] Add 0.2 mmol of CSA (10-camphorsulfonic acid) to a 100 mL volumetric flask, and add about 80 mL of acetonitrile. After confirming that the CSA is completely dissolved, make up the volume to 100 mL with acetonitrile to prepare Acid Solution D.

[0246] - Preparation of Test Solution E -

[0247] Using a full-volume pipette, add 5 mL of ion-exchanged water to a 100 mL volumetric flask, and add 80 mL of acetonitrile. Add 1 mL of Dye Solution C and 1 mL of Acid Solution D, and make up the volume to 100 mL to prepare Test Solution E.

[0248] The concentration of the chromogen precursor containing the chromogen generated in Test Solution E is 0.02 mmol / L.

[0249] Fill Test Solution E into the test cell (quartz glass, optical path width 10 mm), and perform measurement using an ultraviolet-visible spectrophotometer (manufactured by SHIMADZU CORPORATION, UV-1800).

[0250] The blank medium is set as a water:acetonitrile = 5:95 solution.

[0251] Read the absorption maximum wavelength λmax in the visible light region (380 nm to 750 nm) from the obtained spectrum, and calculate the molar extinction coefficient ε based on the absorbance at this wavelength.

[0252] Calculate the ring-opening rate according to the following calculation formula.

[0253] Ring-opening rate = Molar extinction coefficient when adding 1 molar equivalent of acid to the chromogen precursor / Molar extinction coefficient ε of the chromogen precursor × 100

[0254] As the above-mentioned chromogen precursors preferably used, the following compounds can be cited. In addition, Me represents methyl, Et represents ethyl, Oct represents octyl, and Ph represents phenyl.

[0255] [Chemical formula 11]

[0256]

[0257] [Chemical formula 12]

[0258]

[0259] These chromogen precursors can be used alone, and two or more components can also be used in combination.

[0260] The content of the chromogenic precursor is preferably 0.5% by mass to 10% by mass, more preferably 1% by mass to 5% by mass, relative to the total mass of the image recording layer.

[0261] [Polymerizable compound]

[0262] The image recording layer in the present invention preferably contains a polymerizable compound. In the present invention, the polymerizable compound refers to a compound having a polymerizable group.

[0263] In the present invention, even for a compound having a polymerizable group, a compound corresponding to the thermoplastic resin contained in the above-mentioned thermoplastic resin particles, the polymer particles described later, and the binder polymer other than the thermoplastic resin described later does not belong to the polymerizable compound.

[0264] The polymerizable group is not particularly limited as long as it is a known polymerizable group, but an ethylenically unsaturated group is preferred.

[0265] Moreover, as the polymerizable group, it may be a radical polymerizable group or a cationic polymerizable group, but a radical polymerizable group is preferred.

[0266] Examples of the radical polymerizable group include (meth)acryloyl, allyl, vinylphenyl, vinyl, etc. From the viewpoint of reactivity, (meth)acryloyl is preferred.

[0267] The molecular weight of the polymerizable compound (weight average molecular weight in the case of having a molecular weight distribution) is preferably 50 or more and less than 2,500, more preferably 50 or more and 2,000 or less. Moreover, from the viewpoints of UV printing durability, ink inkability, chemical resistance, and on-machine developability of non-image areas over time, the molecular weight of the polymerizable compound is preferably 1,500 or less.

[0268] From the viewpoint of UV printing durability in the obtained lithographic printing plate, the mass per 1 mol of ethylenically unsaturated bond in the above polymerizable compound (also referred to as "ethylenically unsaturated bond equivalent") is preferably 200 g / mol or less, more preferably 50 g / mol or more and 200 g / mol or less, further preferably 80 g / mol or more and 180 g / mol or less, and particularly preferably 100 g / mol or more and 150 g / mol or less.

[0269] In the present invention, specifically, for example, the ethylenically unsaturated bond equivalent of the polymerizable compound can be obtained in the following manner.

[0270] - Ethylenically unsaturated bond equivalent of dipentaerythritol hexaacrylate (DPHA, molecular weight is 578, 6 ethylenically unsaturated bonds): 578÷6 = 96.3 (g / mol)

[0271] · The vinyl unsaturated bond equivalent of styrene (molecular weight is 104, with 1 vinyl unsaturated bond): 104÷1 = 104 (g / mol)

[0272] · The vinyl unsaturated bond equivalent of "a mixture of 10 g of DPHA and 20 g of styrene": (10 + 20) / {10 / 96.3 + 20 / 104} = 101 (g / mol)

[0273] Regarding the vinyl unsaturated bond equivalent in the present invention, the molecular weight of the polymerizable compound, the number of vinyl unsaturated bonds, and the composition of the polymerizable compound in the above image recording layer can be determined by known methods, and can be obtained by the above calculation method.

[0274] The polymerizable compound used in the present invention can be, for example, a free-radical polymerizable compound or a cationic polymerizable compound, and is preferably an addition polymerizable compound (vinyl unsaturated compound) having at least 1 vinyl unsaturated bond. As the vinyl unsaturated compound, a compound having at least 1 terminal vinyl unsaturated bond is preferred, and a compound having 2 or more terminal vinyl unsaturated bonds is more preferred. The polymerizable compound has, for example, chemical forms such as monomers, prepolymers, i.e., dimers, trimers, or oligomers, or mixtures thereof.

[0275] Among them, as the above polymerizable compound, from the viewpoint of UV printing durability, a polymerizable compound having 3 or more functional groups is preferred, a polymerizable compound having 7 or more functional groups is more preferred, and a polymerizable compound having 10 or more functional groups is further preferred. And, from the viewpoint of UV printing durability in the obtained lithographic printing plate, the above polymerizable compound preferably contains a vinyl unsaturated compound having 3 or more functional groups (preferably 7 or more functional groups, more preferably 10 or more functional groups), and further preferably contains a (meth)acrylate compound having 3 or more functional groups (preferably 7 or more functional groups, more preferably 10 or more functional groups).

[0276] - Oligomer -

[0277] The polymerizable compound contained in the image recording layer preferably contains an oligomer.

[0278] In the present invention, an oligomer means a polymerizable compound having a molecular weight (weight-average molecular weight in the case of having a molecular weight distribution) of 600 or more and 10,000 or less and containing at least 1 polymerizable group.

[0279] From the viewpoints of excellent chemical resistance, UV printing durability, and suppression of on-press development residues, the molecular weight of the oligomer is preferably 1,000 or more and 5,000 or less.

[0280] Further, from the viewpoints of improving chemical resistance and UV printing durability, the number of polymerizable groups in one molecule of the oligomer is preferably 2 or more, more preferably 3 or more, still more preferably 6 or more, and particularly preferably 10 or more.

[0281] Moreover, the upper limit value of the number of polymerizable groups in the oligomer is not particularly limited, but the number of polymerizable groups is preferably 20 or less.

[0282] From the viewpoints of more excellent chemical resistance, UV printing durability, and suppression of on-machine development residues, as the oligomer, the number of polymerizable groups is preferably 7 or more, and the molecular weight is 1,000 or more and 10,000 or less. More preferably, the number of polymerizable groups is 7 or more and 20 or less, and the molecular weight is 1,000 or more and 5,000 or less.

[0283] From the viewpoints of more excellent chemical resistance and UV printing durability, the oligomer preferably includes 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 includes a compound having a urethane bond.

[0284] In this specification, an epoxy residue refers to a structure formed by an epoxy group, and for example, represents the same structure as that obtained by the reaction of an acid group (such as a carboxylic acid group) with an epoxy group.

[0285] <<Compound having a urethane bond>>

[0286] The compound having a urethane bond is not particularly limited. For example, a compound obtained by the reaction of a polyisocyanate compound with a compound having a hydroxyl group and a polymerizable group can be cited.

[0287] Examples of the polyisocyanate compound include bifunctional to pentafunctional polyisocyanate compounds, and bifunctional or trifunctional polyisocyanate compounds are preferred.

[0288] As the polyisocyanate compound, 1,3-bis(isocyanatomethyl)cyclohexane, isophorone diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, 1,3-cyclopentane diisocyanate, 9H-fluorene-2,7-diisocyanate, 9H-fluoren-9-one-2,7-diisocyanate, 4,4'-diphenylmethane diisocyanate, 1,3-phenylene diisocyanate, toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, 2,2-bis(4-isocyanatophenyl)hexafluoropropane, 1,5-naphthalene diisocyanate, dimers and trimers (isocyanurate bonds) of these polyisocyanates, etc. are preferably selected. Further, a biuret obtained by reacting the above polyisocyanate compound with a known amine compound can be used.

[0289] As the compound having a hydroxyl group and a polymerizable group, a compound having 1 hydroxyl group and 1 or more polymerizable groups is preferred, and a compound having 1 hydroxyl group and 2 or more polymerizable groups is more preferred.

[0290] Examples of the compound having a hydroxyl group and a polymerizable group include 2-hydroxyethyl (meth)acrylate, glycerol di(meth)acrylate, trimethylolpropane di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, etc.

[0291] As the compound having a urethane bond, for example, a compound having at least a group represented by the following formula (Ac-1) or formula (Ac-2) is preferred, and a compound having at least a group represented by the following formula (Ac-1) is more preferred.

[0292] [Chemical formula 13]

[0293]

[0294] 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 portion represents the bonding position to other structures.

[0295] As L 1 ~L 4 each independently is preferably an alkylene group having 2 to 20 carbon atoms, more preferably an alkylene group having 2 to 10 carbon atoms, and further preferably an alkylene group having 4 to 8 carbon atoms. Further, the above alkylene group may have a branched chain or a ring structure, but a straight-chain alkylene group is preferred.

[0296] The wavy portions in formula (Ac-1) or formula (Ac-2) are each independently directly bonded to the wavy portion in the group represented by the following formula (Ae-1) or formula (Ae-2).

[0297] [Chemical formula 14]

[0298]

[0299] In formula (Ae-1) and formula (Ae-2), R each independently represents acryloyloxy or methacryloyloxy, and the wavy portion represents the bonding position with the wavy portions in formula (Ac-1) and formula (Ac-2).

[0300] Moreover, as the compound having a urethane bond, a compound in which a polymerizable group is introduced into a polyurethane obtained by the reaction of a polyisocyanate compound and a polyol compound through a polymer reaction can be used. For example, a compound having a urethane bond can be obtained by reacting a compound having an epoxy group and a polymerizable group with a polyurethane oligomer, and the polyurethane oligomer is obtained by reacting a polyol compound having an acid group with a polyisocyanate compound.

[0301] <<Compound having an ester bond>>

[0302] Moreover, the number of polymerizable groups in the compound having an ester bond is preferably 3 or more, more preferably 6 or more.

[0303] <<Compound having an epoxy residue>>

[0304] As the compound having an epoxy residue, a compound containing a hydroxyl group in the compound is preferred.

[0305] Moreover, the number of polymerizable groups in the compound having an epoxy residue is preferably 2 to 6, more preferably 2 to 3.

[0306] As the above-mentioned compound having an epoxy residue, for example, it can be obtained by reacting acrylic acid with a compound having an epoxy group.

[0307] From the viewpoints of improving chemical resistance, UV printing durability, and suppression of on-machine development residues, the content of the oligomer in the above-mentioned image recording layer relative to the total mass of the above-mentioned polymerizable compound is preferably 30% by mass to 100% by mass, more preferably 50% by mass to 100% by mass, and further preferably 80% by mass to 100% by mass.

[0308] The polymerizable compound may further contain a polymerizable compound other than the above-mentioned oligomer.

[0309] The polymerizable compound other than the oligomer can be, for example, a radical polymerizable compound or a cationic polymerizable compound, and is preferably an addition polymerizable compound (olefinically unsaturated compound) having at least one olefinic unsaturated group. As the olefinically unsaturated compound, a compound having at least one olefinic unsaturated group at the terminal is preferred, and a compound having two or more olefinic unsaturated groups at the terminal is more preferred.

[0310] As the polymerizable compound other than the oligomer, from the viewpoint of chemical resistance, a low molecular weight polymerizable compound is preferred. As the low molecular weight polymerizable compound, chemical forms such as monomers, dimers, trimers, or mixtures thereof can be used.

[0311] Moreover, as the low molecular weight polymerizable compound, from the viewpoint of chemical resistance, at least one polymerizable compound selected from the group consisting of a polymerizable compound having three or more olefinic unsaturated groups and a polymerizable compound having an isocyanurate ring structure is preferred.

[0312] In the present invention, the low molecular weight polymerizable compound means a polymerizable compound having a molecular weight (weight average molecular weight in the case of having a molecular weight distribution) of 50 or more and less than 600.

[0313] As the molecular weight of the low molecular weight polymerizable compound, from the viewpoints of excellent chemical resistance, UV printing durability, and suppression of on-machine development residues, it is preferably 100 or more and less than 600, more preferably 300 or more and less than 600, and further preferably 400 or more and less than 600.

[0314] When the polymerizable compound contains a low molecular weight polymerizable compound as the polymerizable compound other than the oligomer (the total amount in the case of containing two or more low molecular weight polymerizable compounds), from the viewpoints of chemical resistance, UV printing durability, and suppression of on-machine development residues, 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 further preferably 10 / 1 to 7 / 3 on a mass basis.

[0315] Examples of the polymeric compound include unsaturated carboxylic acids (e.g., acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid, etc.) and their esters and amides. Esters of unsaturated carboxylic acids and polyhydric alcohol compounds and amides of unsaturated carboxylic acids and polyamine compounds are preferably used. In addition, addition reaction products of unsaturated carboxylic acid esters or amides having nucleophilic substituents such as hydroxyl group, amino group, and mercapto group with monofunctional or polyfunctional isocyanate compounds or epoxy compounds and dehydration condensation reaction products with monofunctional or polyfunctional carboxylic acids are also preferably used. Further, addition reaction products of unsaturated carboxylic acid esters or amides having electrophilic substituents such as isocyanate group and epoxy group with monofunctional or polyfunctional alcohols, amines, and thiols are more preferably used, and substitution reaction products of unsaturated carboxylic acid esters or amides having leaving substituents such as halogen atom and toluenesulfonyloxy group with monofunctional or polyfunctional alcohols, amines, and thiols are even more preferably used. As another example, a compound group in which the above unsaturated carboxylic acids are replaced with unsaturated phosphonic acids, styrene, vinyl ether, etc. can also be used. They are described in Japanese Patent Application Laid-Open No. 2006-508380, Japanese Patent Application Laid-Open No. 2002-287344, Japanese Patent Application Laid-Open No. 2008-256850, Japanese Patent Application Laid-Open No. 2001-342222, Japanese Patent Application Laid-Open No. 9-179296, Japanese Patent Application Laid-Open No. 9-179297, Japanese Patent Application Laid-Open No. 9-179298, Japanese Patent Application Laid-Open No. 2004-294935, Japanese Patent Application Laid-Open No. 2006-243493, Japanese Patent Application Laid-Open No. 2002-275129, Japanese Patent Application Laid-Open No. 2003-64130, Japanese Patent Application Laid-Open No. 2003-280187, Japanese Patent Application Laid-Open No. 10-333321, etc.

[0316] As specific examples of ester monomers of polyol compounds and unsaturated carboxylic acids, as acrylate esters, there are ethylene glycol diacrylate, 1,3-butanediol diacrylate, tetramethylene glycol diacrylate, propylene glycol diacrylate, trimethylolpropane triacrylate, hexanediol diacrylate, tetraethylene glycol diacrylate, pentaerythritol tetraacrylate, sorbitol triacrylate, ethylene oxide (EO) modified triacrylate of isocyanuric acid, polyester acrylate oligomers, and the like. As methacrylate esters, there are tetramethylene glycol dimethacrylate, neopentyl glycol dimethacrylate, trimethylolpropane trimethacrylate, ethylene glycol dimethacrylate, pentaerythritol trimethacrylate, bis[4-(3-methacryloyloxy-2-hydroxypropoxy)phenyl]dimethylmethane, bis[4-(methacryloyloxyethoxy)phenyl]dimethylmethane, and the like. Further, as specific examples of amide monomers of polyamine compounds and unsaturated carboxylic acids, there are methylene bisacrylamide, methylene bismethacrylamide, 1,6-hexamethylene bisacrylamide, 1,6-hexamethylene bismethacrylamide, diethylenetriamine triacrylamide, xylylene bisacrylamide, diphenyl bismethacrylamide, and the like.

[0317] Moreover, urethane-based addition polymerizable compounds produced by the addition reaction of isocyanate and hydroxyl group are also preferred. Specific examples thereof include vinyl urethane compounds containing two or more polymerizable vinyl groups formed by adding a polyisocyanate compound having two or more isocyanate groups in one molecule to a hydroxyl group-containing vinyl monomer represented by the following formula (M) as described in Japanese Patent Publication No. Sho 48-41708.

[0318] CH2=C(R M4 )COOCH2CH(R M5 )OH (M)

[0319] In formula (M), R M4 and R M5 each independently represent a hydrogen atom or a methyl group.

[0320] Further, it is also preferable to use urethane acrylates described in Japanese Patent Application Laid-Open No. Sho 51-37193, Japanese Patent Publication No. Hei 2-32293, Japanese Patent Publication No. Hei 2-16765, Japanese Patent Application Laid-Open No. 2003-344997, Japanese Patent Application Laid-Open No. 2006-65210; urethane compounds having an ethylene oxide-based skeleton described in Japanese Patent Publication No. Sho 58-49860, Japanese Patent Publication No. Sho 56-17654, Japanese Patent Publication No. Hei 62-39417, Japanese Patent Publication No. Hei 62-39418, Japanese Patent Application Laid-Open No. 2000-250211, Japanese Patent Application Laid-Open No. 2007-94138; and urethane compounds having a hydrophilic group described in U.S. Patent No. 7153632, Japanese Patent Application Laid-Open No. Hei 8-505958, Japanese Patent Application Laid-Open No. 2007-293221, Japanese Patent Application Laid-Open No. 2007-293223.

[0321] Specific examples of the oligomers are shown in the following table, but the oligomers used in the present invention are not limited thereto.

[0322] As the oligomers, commercially available products can be used, such as UA510H, UA-306H, UA-306I, UA-306T (all manufactured by KYOEISHA CHEMICAL CO., LTD.), UV-1700B, UV-6300B, UV7620EA (all manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), U-15HA (manufactured by Shin-Nakamura Chemical Co., Ltd.), EBECRYL450, EBECRYL657, EBECRYL885, EBECRYL800, EBECRYL3416, EBECRYL860 (all manufactured by DAICEL-ALLNEX LTD.), etc., but are not limited thereto.

[0323] - Specific Compound B1 -

[0324] From the viewpoint of improving printing durability, the polymerizable compound preferably contains a compound having an ethylenically unsaturated bond value of 5.0 mmol / g or more (hereinafter, also referred to as Specific Compound B1).

[0325] The ethylenically unsaturated bond value of Specific Compound B1 is preferably 5.5 mmol / g or more, more preferably 6.0 mmol / g or more. Regarding the upper limit of the ethylenically unsaturated bond value of Specific Compound B1, for example, 10.0 mmol / g or less can be mentioned, and more preferably 8.5 mmol / g or less.

[0326] Here, the olefinic unsaturation value of the compound in the present invention is determined by the following method. First, for a specified sample amount (e.g., 0.2 g) of the compound, the structure of the compound is determined using, for example, pyrolysis GC / MS, FT-IR, NMR, TOF-SIMS, etc., and the total amount (mmol) of olefinic unsaturated groups is determined. The olefinic unsaturation value in the compound is calculated by dividing the total amount (mmol) of the determined olefinic unsaturated groups by the sample amount (g) of the compound.

[0327] From the viewpoint of satisfying the above C═C value, the specific compound B1 is preferably a compound represented by the following formula (I).

[0328] Formula (I): X-(Y)n

[0329] In formula (I), X represents an n-valent organic group having a hydrogen-bonding group, Y represents a monovalent group having two or more olefinic unsaturated groups, n represents an integer of 2 or more, and the molecular weight of X / (the molecular weight of Y×n) is 1 or less.

[0330] The hydrogen-bonding group in X of formula (I) is not particularly limited as long as it is a group capable of forming a hydrogen bond, and it may be a hydrogen-bond donating group, a hydrogen-bond accepting group, or both. Examples of the above hydrogen-bonding group include a hydroxyl group, a carboxyl group, an amino group, a carbonyl group, a sulfonyl group, a urethane group, a urea group, an imide group, an amide group, a sulfonamide group, etc. Among them, from the viewpoints of on-machine developability and printing durability, the above hydrogen-bonding group preferably contains at least one group selected from the group consisting of a urethane group, a urea group, an imide group, an amide group, and a sulfonamide group, more preferably contains at least one group selected from the group consisting of a urethane group, a urea group, an imide group, and an amide group, still more preferably is at least one group selected from the group consisting of a urethane group, a urea group, and an imide group, and particularly preferably contains at least one group selected from the group consisting of a urethane group and a urea group.

[0331] X in formula (I) is preferably an organic group not having an olefinic unsaturation bond.

[0332] Furthermore, from the viewpoints of on-machine developability and printing durability, X in formula (I) is preferably a monovalent to n-valent aliphatic hydrocarbon group, a monovalent to n-valent aromatic hydrocarbon group, or a group formed by combining two or more structures selected from the group consisting of a urethane bond, a urea bond, a biuret bond, and a urethane-formate bond, and more preferably a monovalent to n-valent aliphatic hydrocarbon group, a monovalent to n-valent aromatic hydrocarbon group, or a group formed by combining two or more structures selected from the group consisting of a urethane bond, a urea bond, and a biuret bond.

[0333] From the viewpoints of on-machine developability and printing durability, X in formula (I) is preferably a group obtained by removing terminal isocyanate groups from a polymer obtained by polymerizing a polyfunctional isocyanate compound (including adducts of polyfunctional alcohol compounds such as trimethylolpropane adducts), more preferably a group obtained by removing terminal isocyanate groups from a polymer obtained by polymerizing a bifunctional isocyanate compound (including adducts of polyfunctional alcohol compounds), and particularly preferably a group obtained by removing terminal isocyanate groups from a polymer obtained by polymerizing hexamethylene diisocyanate (including adducts of polyfunctional alcohol compounds).

[0334] From the viewpoints of on-machine developability and printing durability, the molecular weight of X in formula (I) is preferably 100 to 1,000, more preferably 150 to 800, and particularly preferably 150 to 500.

[0335] The ethylenically unsaturated group in Y of formula (I) is not particularly limited. From the viewpoints of reactivity, on-machine developability, and printing durability, it is preferably at least one group selected from the group consisting of vinylphenyl, vinyl ester group, vinyl ether group, allyl group, (meth)acryloyloxy group, and (meth)acrylamide group. From the same viewpoints as above, as the ethylenically unsaturated group in Y of formula (I), it is more preferably at least one group selected from the group consisting of vinylphenyl, (meth)acryloyloxy group, and (meth)acrylamide group, and further preferably (meth)acryloyloxy group. That is, from the viewpoints of on-machine developability and printing durability, the ethylenically unsaturated group in Y of formula (I) preferably contains (meth)acryloyloxy group.

[0336] Y in formula (I) is preferably a group having 3 or more (meth)acryloyloxy groups, more preferably a group having 5 or more (meth)acryloyloxy groups, and further preferably a group having 5 or more and 12 or less (meth)acryloyloxy groups.

[0337] From the viewpoints of on-machine developability and printing durability, Y in formula (I) may have a structure represented by the following formula (Y-1) or formula (Y-2).

[0338] [Chemical formula 15]

[0339]

[0340] In formula (Y-1) and formula (Y-2), R independently represents acryloyl group or methacryloyl group, and the wavy line part represents the bonding position to other structures.

[0341] In formula (Y-1) or formula (Y-2), it is preferred that R are all the same group. And in formula (Y-1) or formula (Y-2), R is preferably acryloyl group.

[0342] Moreover, the n Ys in formula (I) are all the same group.

[0343] From the viewpoints of in-machine developability and printing durability, the molecular weight of Y in formula (I) is preferably 200 or more and 1,000 or less, more preferably 250 or more and 800 or less.

[0344] n in formula (I) is an integer of 2 or more, and from the viewpoints of in-machine developability and printing durability, it is more preferably 2 to 3.

[0345] The molecular weight of X / (the molecular weight of Y × n) is 1 or less, and from the viewpoints of in-machine developability and printing durability, it is preferably 0.01 to 0.8, more preferably 0.1 to 0.5.

[0346] As described above, the structure of the specific compound B1 is preferably selected as the structure in which the terminal isocyanate group of the polymer (including the adduct) of the polyfunctional isocyanate compound is sealed with a compound having an ethylenically unsaturated group. Among them, as the polymer of the polyfunctional isocyanate compound, a polymer of a bifunctional isocyanate compound is preferred.

[0347] Moreover, from the viewpoints of in-machine developability and printing durability, the specific compound B1 is preferably a compound obtained by reacting the terminal isocyanate group of a polymer obtained by polymerizing a polyfunctional ethylenically unsaturated compound having a hydroxyl group (also referred to as a hydroxy group) at the terminal with a polyfunctional isocyanate compound. Moreover, from the same viewpoints as above, the specific compound B1 is more preferably a compound obtained by reacting the terminal isocyanate group of a polymer (including the adduct of a polyfunctional alcohol compound) obtained by polymerizing a polyfunctional ethylenically unsaturated compound having a hydroxyl group with a bifunctional isocyanate compound. Moreover, from the same viewpoints as above, the specific compound B1 is particularly preferably a compound obtained by reacting the terminal isocyanate group of a polymer (including the adduct of a polyfunctional alcohol compound) obtained by polymerizing a polyfunctional ethylenically unsaturated compound having a hydroxyl group with hexamethylene diisocyanate.

[0348] As the above-mentioned polyfunctional isocyanate compound, there is no particular limitation, and known polyfunctional isocyanate compounds can be used, which can be aliphatic polyfunctional isocyanate compounds or aromatic polyfunctional isocyanate compounds. Specifically, for example, 1,3-bis(isocyanatomethyl)cyclohexane, isophorone diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, 1,3-cyclopentane diisocyanate, 9H-fluorene-2,7-diisocyanate, 9H-fluorenone-2,7-diisocyanate, 4,4'-diphenylmethane diisocyanate, 1,3-phenylene diisocyanate, toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, 2,2-bis(4-isocyanatophenyl)hexafluoropropane, 1,5-naphthalene diisocyanate, dimers and trimers (isocyanurate bonds) of these polyisocyanates, etc. can be preferably selected. And, a biuret obtained by reacting the above polyisocyanate compound with a known amine compound can be used.

[0349] Moreover, the above-mentioned polyfunctional ethylenically unsaturated compound having a hydroxyl group is preferably a polyfunctional ethylenically unsaturated compound having 3 or more hydroxyl groups, more preferably a polyfunctional ethylenically unsaturated compound having 5 or more hydroxyl groups. The above-mentioned polyfunctional ethylenically unsaturated compound having a hydroxyl group is preferably a polyfunctional (meth)acrylate compound having a hydroxyl group.

[0350] From the viewpoints of on-machine developability and printing durability, the specific compound B1 preferably has at least one structure selected from the group consisting of an adduct structure, a biuret structure, and an isocyanurate structure. From the same viewpoints as above, the specific compound B1 more preferably has at least one structure selected from the group consisting of a trimethylolpropane adduct structure, a biuret structure, and an isocyanurate structure, and particularly preferably has a trimethylolpropane adduct structure.

[0351] From the viewpoints of on-machine developability and printing durability, the specific compound B1 preferably has a structure represented by any one of the following formulas (A-1) to (A-3), and more preferably has a structure represented by the following formula (A-1).

[0352] [Chemical formula 16]

[0353]

[0354] In formula (A-1), R A1 represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and the wavy line part represents the bonding position to other structures.

[0355] From the viewpoints of on-machine developability and printing durability, R in formula (A-1)A1 It is preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms, still more preferably a methyl group or an ethyl group, and particularly preferably an ethyl group.

[0356] From the viewpoints of on-machine developability and printing durability, the specific compound B1 is preferably a (meth)acrylate compound having a urethane group, that is, a urethane (meth)acrylate oligomer.

[0357] Regarding the specific compound B1, as long as the ethylenically unsaturated bond value is 5.0 mmol / g or more, it may be an oligomer having a polyester bond (hereinafter, also referred to as a polyester (meth)acrylate oligomer), or it may be an oligomer having an epoxy residue (hereinafter, also referred to as an epoxy (meth)acrylate oligomer).

[0358] Here, the epoxy residue in the epoxy (meth)acrylate oligomer is as described above.

[0359] The number of ethylenically unsaturated groups in the specific compound B1, that is, the polyester (meth)acrylate oligomer, is preferably 3 or more, and more preferably 6 or more.

[0360] As the specific compound B1, that is, the epoxy (meth)acrylate oligomer, a compound containing a hydroxyl group in the compound is preferred. And the number of ethylenically unsaturated groups in the epoxy (meth)acrylate oligomer is preferably 2 to 6, and more preferably 2 to 3. As the above-mentioned epoxy (meth)acrylate oligomer, for example, it can be obtained by reacting acrylic acid with a compound having an epoxy group.

[0361] As the molecular weight of the specific compound B1 (in the case of having a molecular weight distribution, it is the weight-average molecular weight), it is preferably more than 1,000, more preferably 1,100 to 10,000, and still more preferably 1,100 to 5,000.

[0362] The specific compound B1 can be a synthetic product or a commercially available product.

[0363] As specific examples of the specific compound B1, for example, the commercially available products listed below can be cited, but the specific compound B1 used in the present invention is not limited to these. In addition, the number of functional groups (or average number of functional groups) of the ethylenically unsaturated group and the C═C value are shown in parentheses.

[0364] As specific examples of the specific compound B1, there can be mentioned urethane (meth)acrylate oligomers such as U-10HA (number of functional groups: 10, C═C value: 8 mmol / g), U-15HA (number of functional groups: 15, C═C value: 6 mmol / g) manufactured by Shin-Nakamura Chemical Co., Ltd., UA-510H (number of functional groups: 10, C═C value: 8 mmol / g) manufactured by KYOEISHA CHEMICAL CO., LTD., KRM8452 (number of functional groups: 10, C═C value: 7 mmol / g) manufactured by DAICEL-ALLNEX LTD., CN8885NS (number of functional groups: 9, C═C value: 6 mmol / g), CN9013NS (number of functional groups: 9, C═C value: 6 mmol / g) manufactured by Sartomer Company, Inc.

[0365] Furthermore, as specific examples of the specific compound B1, there can be mentioned epoxy (meth)acrylate oligomers such as NK Oligo EA-7420 / PGMAc (number of functional groups: 10 to 15, C═C value: 5 mmol / g) manufactured by Shin-Nakamura Chemical Co., Ltd., CN153 (C═C value: 5 mmol / g) manufactured by Sartomer Company, Inc.

[0366] Moreover, as specific examples of the specific compound B1, there can be mentioned polyester (meth)acrylate oligomers such as CN2267 (C═C value: 5 mmol / g) manufactured by Sartomer Company, Inc.

[0367] When using the specific compound B1, the content of the specific compound B1 in the image recording layer relative to the total mass of the polymerizable compounds is preferably 10% by mass to 100% by mass, more preferably 50% by mass to 100% by mass, and still more preferably 80% by mass to 100% by mass.

[0368] - Specific compound B2 -

[0369] As the polymerizable compound, a compound having one or two ethylenically unsaturated bond groups (hereinafter, also referred to as the specific compound B2) can be included as a low molecular compound.

[0370] The preferred mode of the ethylenically unsaturated group possessed by the specific compound B2 is the same as that of the ethylenically unsaturated group in the specific compound B1.

[0371] Further, from the viewpoint of suppressing the decrease in on-machine developability, the specific compound B2 is preferably a compound having two ethylenically unsaturated bond groups (i.e., a bifunctional polymerizable compound).

[0372] As the specific compound B2, from the viewpoints of on-machine developability and printing durability, a methacrylate compound, i.e., a compound having a methacryloyloxy group, is preferred.

[0373] As the specific compound B2, from the viewpoint of on-machine developability, it preferably contains an alkyleneoxy structure or a urethane bond.

[0374] As the molecular weight of the specific compound B2 (weight average molecular weight in the case of having a molecular weight distribution), it is preferably 50 or more and less than 1,000, more preferably 200 to 900, and further preferably 250 to 800.

[0375] Specific examples of the specific compound B2 are shown below, but the specific compound B2 used in the present invention is not limited to these. In addition, in the compounds of the following (2), for example, n + m = 10.

[0376] [Chemical formula 17]

[0377]

[0378] As the specific compound B2, commercially available products shown below can be used, but the specific compound B2 used in the present invention is not limited to these.

[0379] Specific examples of the specific compound B2 include ethoxylated bisphenol A dimethacrylate such as BPE-80N (the compound of the above (1)), BPE-100, BPE-200, BPE-500 manufactured by Shin-Nakamura Chemical Co., Ltd., and CN104 (the compound of the above (1)) manufactured by Sartomer Company, Inc.

[0380] In addition, specific examples of the specific compound B2 include ethoxylated bisphenol A diacrylate such as A-BPE-10 (the compound of the above (2)) and A-BPE-4 manufactured by Shin-Nakamura Chemical Co., Ltd.

[0381] Moreover, specific examples of the specific compound B2 include bifunctional methacrylate such as FST 510 manufactured by AZ Electronics Corporation.

[0382] Herein, the above-mentioned "FST 510" is a reaction product of 1 mole of 2,2,4-trimethylhexamethylene diisocyanate and 2 moles of 2-hydroxyethyl methacrylate, and is an 82% by mass solution of the compound of the above (3) in methyl ethyl ketone.

[0383] From the viewpoints of on-machine developability and printing durability, the content of the specific compound B2 is preferably 1% by mass to 60% by mass, more preferably 5% by mass to 55% by mass, and further preferably 5% by mass to 50% by mass, based on the total mass of the image recording layer.

[0384] When using the specific compound B2, the content of the specific compound B2 in the image recording layer relative to the total mass of the polymerizable compounds is preferably 10% by mass to 100% by mass, more preferably 50% by mass to 100% by mass, and further preferably 80% by mass to 100% by mass.

[0385] Details of the usage methods such as the structure of the polymerizable compounds, whether used alone or in combination, and the addition amount can be arbitrarily set.

[0386] Among them, from the viewpoint of UV printing durability, the above-mentioned image recording layer preferably contains two or more polymerizable compounds.

[0387] Based on the total mass of the image recording layer, the content of the polymerizable compounds (in the case of containing two or more polymerizable compounds, it is 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 further preferably 15% by mass to 60% by mass.

[0388] Moreover, the content of the thermoplastic resin contained in the thermoplastic resin particles in the image recording layer relative to the total mass of the polymerizable compounds is preferably more than 0% by mass and 400% by mass or less, more preferably 25% by mass to 300% by mass, and further preferably 50% by mass to 200% by mass.

[0389] In the image recording layer, the thermoplastic resin contained in the thermoplastic resin particles and the above-mentioned polymerizable compounds preferably adopt an island structure. For example, a structure in which the above-mentioned polymerizable compounds are dispersed in an island shape (discontinuous phase) in the sea (continuous phase) of the thermoplastic resin can be adopted. It is considered that by setting the content of the thermoplastic resin contained in the thermoplastic resin particles relative to the total mass of the polymerizable compounds within the above range, it is easy to form an island structure.

[0390] 〔Initiator〕

[0391] The image recording layer used in the present invention contains an initiator.

[0392] As an initiator, a polymerization initiator is preferred.

[0393] As the polymerization initiator, there is no particular limitation, and examples thereof include an electron-accepting polymerization initiator, an electron-donating polymerization initiator, and the like.

[0394] - Electron-accepting polymerization initiator -

[0395] Preferably, the above image recording layer contains an electron-accepting polymerization initiator.

[0396] The electron-accepting polymerization initiator used in the present invention is a compound that generates polymerization initiating species such as free radicals or cations by the energy of light, heat, or both, and known thermal polymerization initiators, compounds having bonds with small bond dissociation energies, photoinitiators, etc. can be appropriately selected and used.

[0397] As the electron-accepting polymerization initiator, a radical polymerization initiator is preferred, and an onium salt compound is more preferred.

[0398] Furthermore, as the electron-accepting polymerization initiator, an infrared-sensitive polymerization initiator is preferred.

[0399] The electron-accepting polymerization initiator can be used alone or two or more thereof can be used simultaneously.

[0400] As the radical polymerization initiator, for example, (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, (k) onium salt compounds can be cited.

[0401] (a) As the organic halide, for example, the compounds described in paragraphs 0022 to 0023 of JP-A-2008-195018 are preferred.

[0402] (b) As the carbonyl compound, for example, the compounds described in paragraph 0024 of JP-A-2008-195018 are preferred.

[0403] (c) As the azo compound, for example, the azo compounds described in JP-A-8-108621 can be used.

[0404] (d) As the organic peroxide, for example, the compounds described in paragraph 0025 of JP-A-2008-195018 are preferred.

[0405] (e) As the metallocene compound, for example, the compounds described in paragraph 0026 of JP-A-2008-195018 are preferred.

[0406] As the (f) azide compound, compounds such as 2,6-bis(4-azidobenzylidene)-4-methylcyclohexanone can be cited, for example.

[0407] (g) As the hexaarylbiimidazole compound, for example, the compounds described in paragraph 0027 of JP-A-2008-195018 are preferred.

[0408] As the (i) disulfone compound, for example, the compounds described in JP-A-61-166544 and JP-A-2002-328465 can be cited.

[0409] (j) As the oxime ester compound, for example, the compounds described in paragraphs 0028 to 0030 of JP-A-2008-195018 are preferred.

[0410] Among the above electron-accepting polymerization initiators, as preferred electron-accepting polymerization initiators, from the viewpoint of curability, oxime ester compounds and onium salt compounds can be cited. Among them, from the viewpoint of UV printing durability, iodonium salt compounds, sulfonium salt compounds or azinium salt compounds are preferred, iodonium salt compounds or sulfonium salt compounds are more preferred, and iodonium salt compounds are further preferred.

[0411] Specific examples of these compounds are shown below, but the present invention is not limited thereto.

[0412] As an example of the iodonium salt compound, a diaryliodonium salt compound is preferred. In particular, a diphenyliodonium salt compound substituted with an electron-donating group such as an alkyl group or an alkoxy group is more preferred, and an asymmetric diphenyliodonium salt compound is preferred. As specific examples, diphenyliodonium = hexafluorophosphate, 4-methoxyphenyl-4-(2-methylpropyl)phenyl iodonium = hexafluorophosphate, 4-(2-methylpropyl)phenyl-p-tolyl iodonium = hexafluorophosphate, 4-hexyloxyphenyl-2,4,6-trimethoxyphenyl iodonium = hexafluorophosphate, 4-hexyloxyphenyl-2,4-diethoxyphenyl iodonium = tetrafluoroborate, 4-octyloxyphenyl-2,4,6-trimethoxyphenyl iodonium = 1-perfluorobutanesulfonate, 4-octyloxyphenyl-2,4,6-trimethoxyphenyl iodonium = hexafluorophosphate, bis(4-tert-butylphenyl)iodonium = tetraphenylborate can be cited.

[0413] As an example of the sulfonium salt compound, a triaryl sulfonium salt compound is preferred, and a triaryl sulfonium salt compound in which at least a part of an electron-withdrawing group, such as a group on an aromatic ring, is substituted with a halogen atom is particularly preferred, and a triaryl sulfonium salt compound in which the total number of halogen atoms substituted on the aromatic ring is 4 or more is further preferred. As a specific example, 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, tris(2,4-dichlorophenyl)sulfonium = hexafluorophosphate can be cited.

[0414] Moreover, as a counter anion of the iodonium salt compound and the sulfonium salt compound, a sulfonamide anion or a sulfimide anion is preferred, and a sulfimide anion is more preferred.

[0415] As the sulfonamide anion, an arylsulfonamide anion is preferred.

[0416] Moreover, as the sulfimide anion, a bisarylsulfimide anion is preferred.

[0417] Specific examples of the sulfonamide anion or the sulfimide anion are shown below, but the present invention is not limited to these. In the following specific examples, Ph represents a phenyl group, Me represents a methyl group, and Et represents an ethyl group.

[0418] [Chemical formula 18]

[0419]

[0420] Specific examples of the manner in which the above-mentioned electron-accepting polymerization initiator forms a salt with the electron-donating polymerization initiator described later are shown below, but the present invention is not limited to these.

[0421] [Chemical formula 19]

[0422]

[0423] Moreover, from the viewpoints of color developability, color developability over time after exposure, developability, and UV printing durability in the original lithographic printing plate obtained, the above-mentioned electron-accepting polymerization initiator can preferably be a compound represented by the following formula (I).

[0424] [Chemical formula 20]

[0425]

[0426] In the formula, X represents a halogen atom. Specifically, a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom can be cited. Among these, regarding the chlorine atom or the bromine atom, since the sensitivity is excellent, they are preferred, and a bromine atom is particularly preferred.

[0427] A represents a divalent linking group selected from the group consisting of -CO-, -SO-, -SO2-, -PO- and -PO2-. Among these, -CO-, -SO- and -SO2- are more preferred, and -CO- and -SO2- are particularly preferred. R X1 and R X2 each independently represent a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms.

[0428] As the hydrocarbon constituting the hydrocarbon group, hydrocarbons described in paragraphs 0013 to 0014 of JP-A-2002-162741 can be mentioned. Specifically, as the hydrocarbon, methane, ethane, propane, butane, hexane, nonane, decane, octadecane, cyclopentane, cyclohexane, adamantane, norbornane, decahydronaphthalene, tricyclo[5.2.1.0 2,6 decane, ethylene, propylene, 1-butene, 1-hexene, 1-heptadecene, 2-butene, 2-hexene, 4-nonene, 7-tetradecene, butadiene, pentadiene, 1,9-decadiene, cyclopentene, cyclohexene, cyclooctene, 1,4-cyclohexadiene, 1,5-cyclooctadiene, 1,5,9-cyclododecatriene, norbornene, octahydronaphthalene, bicyclo[2.2.1]hept-2,5-diene, acetylene, 1-propyne, 2-hexyne and other aliphatic hydrocarbons having 1 to 30 carbon atoms; aromatic hydrocarbons such as benzene, naphthalene, anthracene, indene and fluorene.

[0429] One or more of the carbon atoms constituting such a hydrocarbon group may be substituted by a heteroatom selected from an oxygen atom, a nitrogen atom and a sulfur atom.

[0430] As substituents, monovalent non-metal atomic groups obtained by removing hydrogen can be cited. Examples thereof include halogen atoms (-F, -Br, -Cl, -I), hydroxy groups, alkoxy groups, aryloxy groups, mercapto groups, alkylthio groups, arylthio groups, alkyldithio groups, aryldithio groups, amino groups, N-alkylamino groups, N,N-dialkylamino groups, N-arylamino groups, N,N-diarylamino groups, N-alkyl-N-arylamino groups, acyloxy groups, carbamoyloxy groups, N-alkylcarbamoyloxy groups, N-arycarbamoyloxy groups, N,N-dialkylcarbamoyloxy groups, N,N-diarylcarbamoyloxy groups, N-alkyl-N-arycarbamoyloxy groups, alkylsulfinyloxy groups, arylsulfinyloxy groups, acylthio groups, acylamino groups, N-alkylacylamino groups, N-aryacylamino groups, ureido groups, N'-alkylureido groups, N',N'-dialkylureido groups, N'-arylureido groups, N',N'-diarylureido groups, N'-alkyl-N'-arylureido groups, N-alkylureido groups, N-arylureido groups, N'-alkyl-N-alkylureido groups, N'-alkyl-N-arylureido groups, N',N'-dialkyl-N-alkylureido groups, N',N'-dialkyl-N-arylureido groups, N'-aryl-N-alkylureido groups, N'-aryl-N-arylureido groups, N',N'-diaryl-N-alkylureido groups, N',N'-diaryl-N-arylureido groups, N'-alkyl-N'-aryl-N-alkylureido groups, N'-alkyl-N'-aryl-N-arylureido groups, alkoxycarbonylamino groups, aryloxycarbonylamino groups, N-alkyl-N-alkoxycarbonylamino groups, N-alkyl-N-aryloxycarbonylamino groups, N-aryl-N-alkoxycarbonylamino groups, N-aryl-N-aryloxycarbonylamino groups, formyl groups, acyl groups, carboxyl groups and their conjugate bases, alkoxycarbonyl groups, aryloxycarbonyl groups, carbamoyl groups, N-alkylcarbamoyl groups, N,N-dialkylcarbamoyl groups, N-arylcarbamoyl groups, N,N-diarylcarbamoyl groups, N-alkyl-N-arylcarbamoyl groups, alkylsulfinyl groups, arylsulfinyl groups, alkylsulfonyl groups, arylsulfonyl groups, sulfo groups (-SO3H) and their conjugate bases, alkoxysulfonyl groups, aryloxysulfonyl groups, sulfinamoyl groups, N-alkylsulfinamoyl groups, N,N-dialkylsulfinamoyl groups, N-arylsulfinamoyl groups, N,N-diarylsulfinamoyl groups, N-alkyl-N-arylsulfinamoyl groups, sulfamoyl groups, N-alkylsulfamoyl groups, N,N-dialkylsulfamoyl groups, N-arylsulfamoyl groups, N,N-diarylsulfamoyl, N-alkyl-N-arylsulfamoyl, N-acylsulfamoyl and their conjugate bases, N-alkylsulfonylsulfamoyl (-SO2NHS O2(alkyl)) and their conjugate bases, N-arylsulfonylsulfamoyl (-SO2NHSO2(aryl)) and their conjugate bases, N-alkylsulfonylcarbamoyl (-CONHSO2(alkyl)) and their conjugate bases, N-arylsulfonylcarbamoyl (-CONHSO2(aryl)) and their conjugate bases, alkoxysilyl (-Si(Oalkyl)3), aryloxysilyl (-Si(Oaryl)3), hydroxysilyl (-Si(OH)3) and their conjugate bases, phosphonyl (-PO3H2) and their conjugate bases, dialkylphosphonyl (-PO3(alkyl)2), diarylphosphonyl (-PO3(aryl)2), alkylarylphosphonyl (-PO3(alkyl)(aryl)), monoalkylphosphonyl (-PO3H(alkyl)) and their conjugate bases, monoarylphosphonyl (-PO3H(aryl)) and their conjugate bases, phosphonyloxy (-OPO3H2) and their conjugate bases, dialkylphosphonyloxy (-OPO3(alkyl)2), diarylphosphonyloxy (-OPO3(aryl)2), alkylarylphosphonyloxy (-OPO3(alkyl)(aryl)), monoalkylphosphonyloxy (-OPO3H(alkyl)) and their conjugate bases, monoarylphosphonyloxy (-OPO3H(aryl)) and their conjugate bases, cyano, nitro, dialkylboron (-B(alkyl)2), diarylboron (-B(aryl)2), alkylarylboron (-B(alkyl)(aryl)), dihydroxyboron (-B(OH)2) and their conjugate bases, alkylhydroxyboron (-B(alkyl)(OH)) and their conjugate bases, arylhydroxyboron (-B(aryl)(OH)) and their conjugate bases, aryl, alkyl, alkenyl, alkynyl.,

[0431] If possible, these substituents may be bonded to each other or to a substituted hydrocarbon group to form a ring, and the substituents may also be further substituted.

[0432] Preferred substituents include a halogen atom, an alkoxy group, an aryloxy group, an alkyl group, an alkenyl group, an alkynyl group, and an aryl group.

[0433] m x and n x each represent an integer of 1 to 3. Among them, m x +n x = 2 to 4. From the viewpoint of sensitivity, it is preferably m x = 1 and n x = 3 or m x = 2 and nx = 2. When m x and n x are 2 or more, (R1-A) and X can be different respectively. Also, even when m x = 1 and n x = 1, R x2 can also be different from each other.

[0434] Among the compounds represented by the above formula (I), the compounds represented by the following formula (II) or formula (III) have excellent visual recognition and are therefore preferred.

[0435] [Chemical formula 21]

[0436]

[0437] In formula (II) and formula (III), X has the same meaning as X in formula (I), and R 3 , R 4 and R 5 each independently represent a monovalent hydrocarbon group having 1 to 20 carbon atoms.

[0438] Here, R 3 , R 4 and R 5 are preferably aryl groups. Among the groups in which the aryl group is substituted with an amide group, the balance between sensitivity and storage stability is excellent, and they are therefore further preferred.

[0439] Among the compounds represented by the above formula (I), the compounds represented by formula (IV) are particularly preferred.

[0440] [Chemical formula 22]

[0441]

[0442] In formula (IV), R 4 and R 5 each independently represent a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. p and q represent integers from 1 to 5. Among them, p + q = 2 to 6.

[0443] As specific examples of the electron-accepting type polymerization initiator represented by the above formula (I), compounds represented by the following formulae can be cited, etc., but the present invention is not limited to these.

[0444] [Chemical formula 23]

[0445]

[0446] [Chemical formula 24]

[0447]

[0448] [Chemical Formula 25]

[0449]

[0450] [Chemical Formula 26]

[0451]

[0452] [Chemical Formula 27]

[0453]

[0454] [Chemical Formula 28]

[0455]

[0456] [Chemical Formula 29]

[0457]

[0458] From the viewpoints of chemical resistance and UV printing durability, the lowest unoccupied molecular orbital (LUMO) of the electron-accepting polymerization initiator is preferably -3.00 eV or lower, more preferably -3.02 eV or lower.

[0459] Moreover, as the lower limit, it is preferably -3.80 eV or higher, more preferably -3.60 eV or higher.

[0460] Relative to the total mass of the image recording layer, 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.

[0461] [Electron-donating polymerization initiator]

[0462] From the viewpoints of contributing to improving chemical resistance and UV printing durability in the lithographic printing plate, the polymerization initiator preferably further contains an electron-donating polymerization initiator, and more preferably contains both an electron-donating polymerization initiator and the above-mentioned electron-accepting polymerization initiator.

[0463] As the electron-donating polymerization initiator, for example, the following five types can be mentioned.

[0464] (i) Alkyl or aryl acid root type complex: It is considered that the carbon-hetero bond is oxidatively cleaved to generate active radicals. Specifically, borate compounds and the like can be mentioned.

[0465] (ii) Aminoacetic acid compounds: It is considered that the C-X bond on the carbon adjacent to nitrogen is cleaved due to oxidation to generate reactive free radicals. As X, a hydrogen atom, a carboxyl group, a trimethylsilyl group, or a benzyl group is preferred. Specifically, N-phenylglycine (which may have a substituent in the phenyl group), N-phenyliminodiacetic acid (which may have a substituent in the phenyl group), etc. can be cited.

[0466] (iii) Sulfur-containing compounds: Compounds obtained by substituting the nitrogen atom of the above aminoacetic acid compounds with a sulfur atom are considered to generate reactive free radicals through the same action. Specifically, phenylthioacetic acid (which may have a substituent in the phenyl group), etc. can be cited.

[0467] (iv) Tin-containing compounds: Compounds obtained by substituting the nitrogen atom of the above aminoacetic acid compounds with a tin atom can generate reactive free radicals through the same action.

[0468] (v) Sulfinates: They can generate reactive free radicals through oxidation. Specifically, sodium arylsulfinate, etc. can be cited.

[0469] Among these electron-donating polymerization initiators, it is preferred that the image recording layer contains a borate compound. As the borate compound, a tetraarylborate compound or a monoalkyltriarylborate compound is preferred, and from the viewpoint of the stability of the compound, a tetraarylborate compound is more preferred, and a tetraphenylborate compound is particularly preferred.

[0470] As the counter cation of the borate compound, there is no particular limitation, but an alkali metal ion or a tetraalkylammonium ion is preferred, and a sodium ion, a potassium ion, or a tetrabutylammonium ion is more preferred.

[0471] As the borate compound, specifically, sodium tetraphenylborate is preferably cited.

[0472] Moreover, from the viewpoints of chemical resistance and UV printing durability, the highest occupied molecular orbital (HOMO) of the electron-donating polymerization initiator used in the present invention is preferably -6.00 eV or more, more preferably -5.95 eV or more, and further preferably -5.93 eV or more.

[0473] And as the upper limit, it is preferably -5.00 eV or less, more preferably -5.40 eV or less.

[0474] In the present invention, the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) are calculated by the following method.

[0475] First, the free counterions in the compound to be calculated are excluded from the calculation object. For example, in a cationic one-electron-accepting polymerization initiator or a cationic infrared absorber, the counteranions are excluded from the calculation object, and in an anionic one-electron-donating polymerization initiator, the countercations are excluded from the calculation object. Here, "free" means that the compound as the object and its counterions are not linked by a covalent bond.

[0476] Using the quantum chemistry calculation software Gaussian09, structural optimization is performed under DFT (B3LYP / 6-31G(d)).

[0477] Regarding the MO (molecular orbital) energy calculation, it is performed under DFT (B3LYP / 6-31+G(d,p) / CPCM(solvent = methanol)) for the structure obtained through the above structural optimization.

[0478] According to the following formula, the MO energy Ebare (unit: Hartree) obtained through the above MO energy calculation is converted to Escaled (unit: eV) used as the values of HOMO and LUMO in the present disclosure.

[0479] Escaled = 0.823168 × 27.2114 × Ebare - 1.07634

[0480] In addition, 27.2114 is only a coefficient for converting Hartree to eV, and 0.823168 and -1.07634 are adjustment coefficients to determine the HOMO and LUMO of the compound to be calculated so that the calculation matches the measured values.

[0481] Hereinafter, as preferred specific examples of the electron-donating polymerization initiator, B-1 to B-8 and other compounds are shown. Of course, it is not limited to these. And in the following chemical formulas, Bu represents n-butyl, and Z represents a countercation.

[0482] As the countercation represented by Z + Examples include Na + , K + , N + (Bu)4, etc. The above Bu represents n-butyl.

[0483] And as the countercation represented by Z + Examples also preferably include the onium ions in the above electron-accepting polymerization initiators.

[0484] [Chemical formula 30]

[0485]

[0486] [Chemical formula 31]

[0487]

[0488] Further, from the viewpoints of visual recognition, UV printing durability, and stability over time, the above image recording layer preferably contains at least one compound selected from the group consisting of an onium salt compound as the above electron-accepting polymerization initiator and a borate compound as the above electron-donating polymerization initiator, and more preferably contains an onium salt compound as the above electron-accepting polymerization initiator and a borate compound as the above electron-donating polymerization initiator.

[0489] Further, the above image recording layer preferably contains a borate compound as the above electron-donating polymerization initiator, more preferably contains a borate compound as the above electron-donating polymerization initiator, and the HOMO of the above infrared absorber - the HOMO value of the above borate compound is 0.70 eV or less.

[0490] Each of the above HOMOs is calculated by the method described below.

[0491] One kind of electron-donating polymerization initiator may be added, or two or more kinds may be used simultaneously.

[0492] The content of the electron-donating polymerization initiator is preferably 0.01% by mass to 30% by mass, more preferably 0.05% by mass to 25% by mass, and further preferably 0.1% by mass to 20% by mass with respect to the total mass of the image recording layer.

[0493] Further, one of the preferred embodiments in the present invention is a mode in which the above electron-accepting polymerization initiator and the above electron-donating polymerization initiator form a salt.

[0494] Specifically, for example, a mode in which the above onium salt compound is a salt of an onium ion and an anion in the above electron-donating polymerization initiator (for example, a tetraphenylborate anion) can be cited. Further, a more preferred example is an iodonium borate compound in which an iodonium cation (for example, a di-p-tolyl iodonium cation) in the above iodonium salt compound forms a salt with a borate anion in the above electron-donating polymerization initiator.

[0495] Specific examples of the mode in which the above electron-accepting polymerization initiator and the above electron-donating polymerization initiator form a salt are shown below, but the present invention is not limited to these.

[0496] [Chemical formula 32]

[0497]

[0498] In the present invention, when the image recording layer contains an onium ion and an anion of the above-described electron-donating polymerization initiator, the image recording layer contains an electron-accepting polymerization initiator and the above-described electron-donating polymerization initiator.

[0499] 〔Infrared Absorbent〕

[0500] The second embodiment of the original plate for on-machine developing lithographic printing plate according to the present invention contains an infrared absorbent. From the viewpoints of visual recognition, UV durability, and stability over time, the above infrared absorbent preferably contains an infrared absorbent capable of donating electrons to the above initiator, and more preferably contains an infrared absorbent capable of donating electrons to the above polymerization initiator.

[0501] The first embodiment of the original plate for on-machine developing lithographic printing plate according to the present invention contains an infrared absorbent capable of donating electrons to the above initiator. The infrared absorbent capable of donating electrons to the above initiator is not particularly limited, but for example, a decomposable infrared absorbent described later is preferably selected.

[0502] The infrared absorbent is not particularly limited, and examples thereof include pigments and dyes.

[0503] As dyes that can be used as infrared absorbents, commercially available dyes and known dyes described in documents such as "Dye Handbook" (edited by The Society of Synthetic Organic Chemistry, Japan, published in 1970) can be used. Specifically, examples include azo dyes, metal complex azo dyes, pyrazolone azo dyes, naphthoquinone dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinoneimine dyes, methylene dyes, cyanine dyes, squarylium pigments, pyranylium salts, metal thiol complexes, and the like.

[0504] Among these dyes, particularly preferred dyes include cyanine pigments, squarylium pigments, pyranylium salts, nickel thiol complexes, and indocyanine pigments. Moreover, cyanine pigments and indocyanine pigments can be mentioned. Among them, cyanine pigments are particularly preferred.

[0505] As the above infrared absorbent, a cationic polymethine pigment having an oxygen atom or a nitrogen atom at the meta-position is preferred. As the cationic polymethine pigment, cyanine pigments, pyranylium pigments, thiopyrylium pigments, azulium pigments, etc. are preferably selected, and from the viewpoints of ease of acquisition, solvent solubility during the introduction reaction, etc., cyanine pigments are preferred.

[0506] As specific examples of the cyanine pigments, compounds described in paragraphs 0017 to 0019 of Japanese Patent Laid-Open No. 2001-133969, paragraphs 0016 to 0021 of Japanese Patent Laid-Open No. 2002-023360, and paragraphs 0012 to 0037 of Japanese Patent Laid-Open No. 2002-040638 can be cited. Preferably, compounds described in paragraphs 0034 to 0041 of Japanese Patent Laid-Open No. 2002-278057 and paragraphs 0080 to 0086 of Japanese Patent Laid-Open No. 2008-195018 are selected. Particularly preferably, compounds described in paragraphs 0035 to 0043 of Japanese Patent Laid-Open No. 2007-90850 and paragraphs 0105 to 0113 of Japanese Patent Laid-Open No. 2012-206495 are selected.

[0507] In addition, compounds described in paragraphs 0008 to 0009 of Japanese Patent Laid-Open No. 5-5005 and paragraphs 0022 to 0025 of Japanese Patent Laid-Open No. 2001-222101 can also be preferably used.

[0508] As the pigment, compounds described in paragraphs 0072 to 0076 of Japanese Patent Laid-Open No. 2008-195018 are preferred.

[0509] In addition, the above infrared absorber is preferably a decomposable infrared absorber, and more preferably an infrared absorber that decomposes by infrared exposure.

[0510] It is inferred that by using the decomposable infrared absorber pigment as the above infrared absorber, the above infrared absorber or its decomposition product promotes polymerization, and by using the above thermoplastic resin, a film with high polarity can be obtained, and the UV printing durability is excellent due to the interaction between the decomposition product of the above infrared absorber and the above polymerizable compound.

[0511] The above decomposable infrared absorber is preferably an infrared absorber having a function of absorbing infrared rays by infrared exposure and decomposing to develop color. Here, "developing color" means that there is almost no absorption in the visible light region (wavelength region of 400 nm or more and less than 750 nm) before infrared exposure, but absorption occurs in the visible light region by infrared exposure, and it also includes the absorption in the lower wavelength region than the visible light region being shifted to a longer wavelength in the visible light region.

[0512] Hereinafter, the compound obtained by the decomposable infrared absorber absorbing infrared rays by infrared exposure and decomposing to develop color is also referred to as the "color-developing body of the decomposable infrared absorber".

[0513] In addition, the decomposable infrared absorber preferably has a function of absorbing infrared rays by infrared exposure and converting the absorbed infrared rays into heat.

[0514] Regarding the above-mentioned decomposable infrared absorber, any infrared absorber that absorbs at least a part of the light in the infrared wavelength region (wavelength: 750 nm to 1 mm) and decomposes is acceptable, but an infrared absorber having a maximum absorption wavelength in the wavelength region of 750 nm to 1,400 nm is preferred.

[0515] The above-mentioned decomposable infrared absorber is preferably an infrared absorber that decomposes by heat, electron transfer caused by infrared exposure, or both, and more preferably an infrared absorber that decomposes by electron transfer caused by infrared exposure. Here, "decomposing by electron transfer" means that the electrons excited from the HOMO (highest occupied molecular orbital) of the decomposable infrared absorber to the LUMO (lowest unoccupied molecular orbital) by infrared exposure transfer within the molecule to the electron-accepting group (group with a potential close to the LUMO) within the molecule, followed by decomposition.

[0516] As the above-mentioned decomposable infrared absorber, from the viewpoints of color rendering property and UV printing durability of the obtained lithographic printing plate, a cyanine pigment that decomposes by infrared exposure is preferred.

[0517] As the above-mentioned infrared absorber, from the viewpoints of color rendering property and UV printing durability of the obtained lithographic printing plate, a compound represented by the following formula 1-1 is more preferred.

[0518] [Chemical formula 33]

[0519]

[0520] In formula 1-1, R 1 represents a group in which the R 1 -L bond is broken by infrared exposure, and R 11 to R 18 each independently represents a hydrogen atom, a halogen atom, -Ra, -ORb, -SRc, or -NRdRe, and Ra to Re each independently represents a hydrocarbon group. A1, A2, and a plurality of R 11 to R 18 may be linked to form a monocyclic or polycyclic ring. A1 and A2 each independently represent an oxygen atom, a sulfur atom, or a nitrogen atom. n 11 and n 12 each independently represent an integer of 0 to 5, where the sum of n 11 and n 12 is 2 or more, n 13 and n 14 each independently represent 0 or 1, L represents an oxygen atom, a sulfur atom, or -NR 10 -, R 10 represents a hydrogen atom, an alkyl group, or an aryl group, and Za represents a counter ion for neutralizing the charge.

[0521] When the cyanine pigment represented by Formula 1-1 is exposed to infrared light, the R 1 -L bond breaks, and L becomes =O, =S, or =NR 10 , forming a chromophore of the decomposable infrared absorber. R 1 detaches to form a free radical body or an ionic body. These contribute to the polymerization of the polymerizable compound contained in the image recording layer.

[0522] In Formula 1-1, R 11 ~R 18 are each independently preferably a hydrogen atom, -Ra, -ORb, -SRc, or -NRdRe.

[0523] The hydrocarbon group in Ra~Re is preferably a hydrocarbon group having 1 to 30 carbon atoms, more preferably a hydrocarbon group having 1 to 15 carbon atoms, and still more preferably a hydrocarbon group having 1 to 10 carbon atoms. The above hydrocarbon group may be linear, may have a branched chain, or may have a ring structure.

[0524] R in Formula 1-1 11 ~R 14 are each independently preferably a hydrogen atom or a hydrocarbon group, more preferably a hydrogen atom or an alkyl group, and still more preferably a hydrogen atom.

[0525] Moreover, R 11 and R 13 bonded to the carbon atom bonded to the carbon atom to which L is bonded are preferably alkyl groups, and more preferably form a ring by being linked together. The ring thus formed is preferably a 5-membered ring or a 6-membered ring, and more preferably a 5-membered ring.

[0526] R + bonded to the carbon atom bonded to A1 12 and R 14 bonded to the carbon atom to which A2 is bonded are preferably linked to R 15 and R 17 respectively to form a ring.

[0527] R in Formula 1-1 15 is preferably a hydrocarbon group. Moreover, it is preferable that R 15 is linked to R + bonded to the carbon atom to which A1 12 is bonded to form a ring. As the ring thus formed, an indole ring, a pyranylium ring, a thiopyrylium ring, a benzoxazoline ring, or a benzimidazoline ring is preferable, and from the viewpoint of color development, an indole ring is more preferable.

[0528] R in Formula 1-1 17 is preferably a hydrocarbon group. Moreover, it is preferable that R 17 is linked to R 14They are linked to form a ring. As the formed ring, an indole ring, a pyran ring, a thiopyran ring, a benzoxazole ring or a benzimidazole ring is preferred, and from the viewpoint of color development property, an indole ring is more preferred.

[0529] R in Formula 1-1 15 and R 17 are preferably the same group, and when each forms a ring, it is preferred to form the same ring.

[0530] R in Formula 1-1 16 and R 18 are preferably the same group.

[0531] Moreover, from the viewpoint of improving the water solubility of the compound represented by Formula 1-1, R 16 and R 18 each independently preferably has an alkyl group having a (poly)oxyalkylene group or an alkyl group having an anionic structure, more preferably an alkoxyalkyl group, an alkyl group having a carboxylate group or a sulfonate group, and further preferably an alkyl group having a sulfonate group at the terminal. As the above alkyl group, an alkyl group having 1 to 10 carbon atoms is preferred, and an alkyl group having 1 to 4 carbon atoms is more preferred.

[0532] The counter cation of the above anionic structure can be the cation that R 1 -L in Formula 1-1 can contain or A1 + , or can also be an alkali metal cation or an alkaline earth metal cation.

[0533] The counter cation of the above sulfonate group can be the cation that R 1 -L in Formula 1-1 can contain or A1 + , or can also be an alkali metal cation or an alkaline earth metal cation.

[0534] And, to make the maximum absorption wavelength of the compound represented by Formula 1-1 longer in wavelength, and from the viewpoints of color development property and printing durability in a lithographic printing plate, R 16 and R 18 each independently preferably has an alkyl group or an alkyl group having an aromatic ring. As the above alkyl group, an alkyl group having 1 to 10 carbon atoms is preferred, an alkyl group having 1 to 4 carbon atoms is more preferred, and methyl or ethyl is further preferred. As the alkyl group having an aromatic ring, an alkyl group having an aromatic ring at the terminal is preferred, and 2-phenylethyl, 2-naphthylethyl or 2-(9-anthryl)ethyl is more preferred.

[0535] n in Formula 1-1 11 and n 12 are preferably the same integer of 0 to 5, more preferably an integer of 1 to 3, further preferably 1 or 2, and particularly preferably 2.

[0536] In Formula 1-1, A1 and A2 each independently represent an oxygen atom, a sulfur atom, or a nitrogen atom, preferably a nitrogen atom.

[0537] In Formula 1-1, A1 and A2 are preferably the same atom.

[0538] In Formula 1-1, Za represents a counterion that neutralizes the charge. In the case of representing an anion species, examples include a sulfonate ion, a carboxylate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, a p-toluenesulfonate ion, a perchlorate ion, etc., preferably a hexafluorophosphate ion. In the case of representing a cation species, examples include an alkali metal ion, an alkaline earth metal ion, an ammonium ion, a pyridinium ion, a sulfonium ion, etc., preferably a sodium ion, a potassium ion, an ammonium ion, a pyridinium ion, or a sulfonium ion, more preferably a sodium ion, a potassium ion, or an ammonium ion.

[0539] R 11 ~R 18 and R 1 -L can have an anionic structure or a cationic structure. If R 11 ~R 18 and R 1 -L are all electrically neutral groups, then Za is a monovalent counteranion. For example, when R 11 ~R 18 and R 1 -L has two or more anionic structures, Za can also be a countercation.

[0540] Moreover, if the cyanine pigment represented by Formula 1-1 has an electrically neutral structure in the whole compound, then Za does not exist.

[0541] Regarding the group represented by R 1 in Formula 1-1 that undergoes R 1 -L bond cleavage upon infrared exposure, it will be described in detail later.

[0542] As the above-mentioned decomposable infrared absorber, from the viewpoints of color development property and UV printing durability of the obtained lithographic printing plate, a cyanine pigment represented by the following Formula 1-A is more preferred.

[0543] [Chemical Formula 34]

[0544]

[0545] In Formula 1-A, R 1 represents a group that undergoes R 1 -L bond cleavage upon infrared exposure, R 2 and R 3 each independently represent a hydrogen atom or an alkyl group, R 2 and R 3 can be linked to each other to form a ring, Ar1 and Ar 2 each independently represents a group forming a benzene ring or a naphthalene ring, Y 1 and Y 2 each independently represents an oxygen atom, a sulfur atom, -NR 0 -, or a dialkylmethylene group, R 0 represents a hydrogen atom, an alkyl group or an aryl group, R 4 and R 5 each independently represents an alkyl group, a -CO2M group or a -PO3M2 group, M represents a hydrogen atom, a Na atom, a K atom or an onium group, R 6 ~R 9 each independently represents a hydrogen atom or an alkyl group, L represents an oxygen atom, a sulfur atom or -NR 10 -, R 10 represents a hydrogen atom, an alkyl group or an aryl group, Za represents a counter ion for neutralizing the charge.

[0546] In formula 1-A, R 2 ~R 9 and R 0 The alkyl group in is preferably an alkyl group having 1 to 30 carbon atoms, more preferably an alkyl group having 1 to 15 carbon atoms, and still more preferably an alkyl group having 1 to 10 carbon atoms. The above alkyl group may be linear, may have a branched chain, or may have a ring structure.

[0547] Specifically, for example, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, hexadecyl, octadecyl, eicosyl, isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, neopentyl, 1-methylbutyl, isohexyl, 2-ethylhexyl, 2-methylhexyl, cyclohexyl, cyclopentyl and 2-norbornyl can be mentioned.

[0548] Among the alkyl groups, methyl, ethyl, propyl or butyl is preferred.

[0549] The above alkyl group may have a substituent. Examples of the substituent include an alkoxy group, an aryloxy group, an amino group, an alkylthio group, an arylthio group, a halogen atom, a carboxyl group, a carboxylate group, a sulfo group, a sulfonate group, an alkoxycarbonyl group, an aryloxycarbonyl group and a group formed by combining them.

[0550] R 0 The aryl group in is preferably an aryl group having 6 to 30 carbon atoms, more preferably an aryl group having 6 to 20 carbon atoms, and still more preferably an aryl group having 6 to 12 carbon atoms.

[0551] The above 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 carboxyl group, a carboxylate group, a sulfo group, a sulfonate group, an alkoxycarbonyl group, an aryloxycarbonyl group and a group formed by combining them.

[0552] Specifically, for example, phenyl, naphthyl, p-tolyl, p-chlorophenyl, p-fluorophenyl, p-methoxyphenyl, p-dimethylaminophenyl, p-methylthiophenyl, p-phenylthiophenyl, etc. can be cited.

[0553] Among the aryl groups, phenyl, p-methoxyphenyl, p-dimethylaminophenyl or naphthyl is preferred.

[0554] Preferably, R 2 and R 3 are linked to form a ring.

[0555] When R 2 and R 3 are linked to form a ring, a 5-membered ring or a 6-membered ring is preferred, and a 5-membered ring is particularly preferred.

[0556] Y 1 and Y 2 each independently represent an oxygen atom, a sulfur atom, -NR 0 -, or a dialkylmethylene group, preferably -NR 0 -, or a dialkylmethylene group, and more preferably a dialkylmethylene group.

[0557] R 0 represents a hydrogen atom, an alkyl group or an aryl group, and an alkyl group is preferred.

[0558] The alkyl group represented by R 4 or R 5 can be a substituted alkyl group. As the substituted alkyl group represented by R 4 or R 5 the groups represented by any one of the following formulas (a1) to (a4) can be cited.

[0559] [Chemical formula 35]

[0560]

[0561] -R W2 -CO2M (a2)

[0562] -R W3 -PO3M2 (a3)

[0563] -R W4 -SO3M (a4)

[0564] 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 represents an alkyl group having 1 to 12 carbon atoms or -C(=0)-R W5 , RW5 represents an alkyl group having 1 to 12 carbon atoms, 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 Na atom, a K atom or an onium group.

[0565] In formula (a1), as specific examples of the alkylene group represented by R W0 there may be mentioned ethylene, n-propylene, isopropylidene, n-butylene, isobutylene, n-pentylene, isopentylene, n-hexyl, isohexyl, etc., preferably ethylene, n-propylene, isopropylidene, n-butylene, and particularly preferably n-propylene.

[0566] n W1 is preferably 1 to 10, more preferably 1 to 5, and particularly preferably 1 to 3.

[0567] As specific examples of the alkyl group represented by R W1 there may be mentioned methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl, n-hexyl, n-octyl, n-dodecyl, etc., preferably methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, more preferably methyl, ethyl, and particularly preferably methyl.

[0568] The alkyl group represented by R W5 is the same as the alkyl group represented by R W1 and the preferred mode is also the same as the preferred mode of the alkyl group represented by R W1 represented.

[0569] Specific examples of the group represented by formula (a1) are shown below, but the present invention is not limited to these. In the following structural formulas, Me represents methyl, Et represents ethyl, and * represents the bonding site.

[0570] [Chemical formula 36]

[0571]

[0572] In formulas (a2) to (a4), as specific examples of the alkylene group represented by R W2 ~R W4 there may be mentioned methylene, ethylene, n-propylene, isopropylidene, n-butylene, isobutylene, n-pentylene, isopentylene, n-hexyl, isohexyl, n-octylene, n-dodecylene, etc., preferably ethylene, n-propylene, isopropylidene, n-butylene, and particularly preferably ethylene, n-propylene.

[0573] In formula (a3), the two M's may be the same or different.

[0574] In the formulas (a2) to (a4), examples of the onium group represented by M include an ammonium group, an iodonium group, a phosphonium group, a sulfonium group, and the like.

[0575] Among the groups represented by the formulas (a1) to (a4), the groups represented by the formula (a1) or the formula (a4) are preferred.

[0576] In the formula 1-A, R 4 and R 5 are each preferably an unsubstituted alkyl group. R 4 and R 5 are preferably the same group.

[0577] R 6 to R 9 each independently represent a hydrogen atom or an alkyl group, preferably a hydrogen atom.

[0578] Ar 1 and Ar 2 each independently represent a group forming a benzene ring or a naphthalene ring. The benzene ring and the naphthalene ring may have substituents. Examples of the substituents include an alkyl group, an alkoxy group, an aryloxy group, an amino group, an alkylthio group, an arylthio group, a halogen atom, a carboxyl group, a carboxylic acid ester group, a sulfo group, a sulfonic acid ester group, an alkoxycarbonyl group, an aryloxycarbonyl group, an acyloxy group, a phosphonic acid group, and a group formed by combining them. As the substituent, an alkyl group is preferred.

[0579] Moreover, in order to make the maximum absorption wavelength of the compound represented by the formula 1-A longer and from the viewpoints of improving the color developability and the printing durability of the lithographic printing plate, Ar 1 and Ar 2 each independently preferably represent a group forming a naphthalene ring or a benzene ring having an alkyl group or an alkoxy group as a substituent, more preferably a group forming a naphthalene ring or a benzene ring having an alkoxy group as a substituent, and particularly preferably a group forming a naphthalene ring or a benzene ring having a methoxy group as a substituent.

[0580] In the formula 1-A, Ar 1 or Ar 2 is preferably a group forming a group represented by the following formula (b1).

[0581] [Chemical formula 37]

[0582]

[0583] In the formula (b1), R 19 represents an alkyl group having 1 to 12 carbon atoms. n3 represents an integer of 1 to 4. * represents a bonding site.

[0584] Za represents a counter ion for neutralizing the charge. Wherein, the compound represented by Formula 1-A has an ionic substituent corresponding to its structure, and Za is not required when neutralization of the charge is not required. When Za represents an anion species, sulfonate ions, carboxylate ions, tetrafluoroborate ions, hexafluorophosphate ions, p-toluenesulfonate ions, perchlorate ions, etc. can be cited, preferably hexafluorophosphate ions. When Za represents a cationic species, alkali metal ions, alkaline earth metal ions, ammonium ions, pyridinium ions or sulfonium ions can be cited, preferably sodium ions, potassium ions, ammonium ions, pyridinium ions or sulfonium ions, more preferably sodium ions, potassium ions or ammonium ions.

[0585] R 1 ~R 9 , R 0 ,Ar 1 ,Ar 2 , Y 1 and Y 2 It can have an anionic structure or a cationic structure. If R 1 ~R 9 , R 0 ,Ar 1 ,Ar 2 , Y 1 and Y 2 All are electrically neutral groups, then Za is a monovalent counter anion, but for example in R 1 ~R 9 , R 0 ,Ar 1 ,Ar 2 , Y 1 and Y 2 When there are two or more anionic structures, Za can also serve as a counter cation.

[0586] Next, the above formula 1-1 and formula 1-A are represented by R 1 Indicates that R 1 The group in which the -L bond is broken is explained.

[0587] When L is an oxygen atom in Formula 1-1 or Formula 1-A, from the viewpoint of color development, R 1 A group represented by any one of the following formulae (1-1) to (1-7) is preferred, and a group represented by any one of the following formulae (1-1) to (1-3) is more preferred.

[0588] [Chemical formula 38]

[0589]

[0590] In formulas (1-1) to (1-7), ● represents the bonding site of the oxygen atom represented by L in formula 1-1 or formula 1-A, and R 20 each independently represents a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, -OR 24 , -NR 25 R 26 or -SR 27 , and R 21 each independently represents a hydrogen atom, an alkyl group or an aryl group, and R 22 represents an aryl group, -OR 24 , -NR 25 R 26 , -SR 27 , -C(=O)R 28 , -OC(=O)R 28 or a halogen atom, and R 23 represents an aryl group, an alkenyl group, an alkoxy group or an oxonium group, and R 24 to R 27 each independently represents a hydrogen atom, an alkyl group or an aryl group, and R 28 represents an alkyl group, an aryl group, -OR 24 , -NR 25 R 26 or -SR 27 , and Z 1 represents a counter ion for neutralizing the charge.

[0591] R 20 , R 21 and R 24 to R 28 When they are alkyl groups, the preferred modes are the same as those of the alkyl groups in R 2 to R 9 and R 0 .

[0592] The number of carbon atoms of the alkenyl groups in R 20 and R 23 is preferably 1 to 30, more preferably 1 to 15, and still more preferably 1 to 10.

[0593] R 20 to R 28 When they are aryl groups, the preferred modes are the same as those of the aryl groups in R 0 .

[0594] From the viewpoint of color rendering property, R 20 in formula (1-1) is preferably an alkyl group, an alkenyl group, an aryl group, -OR 24 , -NR 25 R 26 or -SR 27 , more preferably an alkyl group, -OR 24 , -NR 25 R26 or -SR 27 , more preferably an alkyl group or -OR 24 , particularly preferably -OR 24 .

[0595] Moreover, in the case where R in formula (1-1) 20 is an alkyl group, the above alkyl group may be an alkyl group having an arylthio group, an alkoxycarbonyl group or an arylsulfonyl group at the α-position, preferably an alkyl group having an arylthio group or an alkoxycarbonyl group at the α-position.

[0596] In the case where R in formula (1-1) 20 is -OR 24 , R 24 is preferably an alkyl group, more preferably an alkyl group having 1 to 8 carbon atoms, further preferably an isopropyl group or a tert-butyl group, and particularly preferably a tert-butyl group.

[0597] In the case where R in formula (1-1) 20 is an alkenyl group, the above alkenyl group may be an alkenyl group having an aryl group or a hydroxyaryl group.

[0598] From the viewpoint of color rendering property, R in formula (1-2) 21 is preferably a hydrogen atom.

[0599] Moreover, from the viewpoint of color rendering property, R in formula (1-2) 22 is preferably -C(=O)OR 24 , -OC(=O)OR 24 or a halogen atom, more preferably -C(=O)OR 24 or -OC(=O)OR 24 . In the case where R in formula (1-2) 22 is C(=O)OR 24 or -OC(=O)OR 24 , R 24 is preferably an alkyl group.

[0600] From the viewpoint of color rendering property, R in formula (1-3) 21 is independently preferably a hydrogen atom or an alkyl group, and at least one R in formula (1-3) 21 is more preferably an alkyl group.

[0601] Moreover, R 21 in the alkyl group preferably has 1 to 10 carbon atoms, more preferably 3 to 10 carbon atoms.

[0602] Furthermore, R 21 in the alkyl group preferably has a branched chain or a cyclic structure, more preferably an isopropyl group, a cyclopentyl group, a cyclohexyl group or a tert-butyl group. And R 21 in the alkyl group is preferably a secondary alkyl group or a tertiary alkyl group.

[0603] Also, from the viewpoint of color rendering property, R in formula (1-3) 23 is preferably an aryl group, an alkoxy group or an onium group, more preferably a p-dimethylaminophenyl group or a pyridinium group, and still more preferably a pyridinium group.

[0604] As the onium group in R 23 , pyridinium group, ammonium group, sulfonium group, etc. can be mentioned. The onium group may have a substituent. As the substituent, alkyl group, aryl group, alkoxy group, aryloxy group, amino group, alkylthio group, arylthio group, halogen atom, carboxyl group, sulfo group, alkoxycarbonyl group, aryloxycarbonyl group, and a group formed by combining them, etc. can be mentioned, but alkyl group, aryl group, and a group formed by combining them are preferred.

[0605] Among them, a pyridinium group is preferred, and more preferably N-alkyl-3-pyridinium group, N-benzyl-3-pyridinium group, N-(alkoxypolyalkyleneoxyalkyl)-3-pyridinium group, N-alkoxycarbonylmethyl-3-pyridinium group, N-alkyl-4-pyridinium group, N-benzyl-4-pyridinium group, N-(alkoxypolyalkyleneoxyalkyl)-4-pyridinium group, N-alkoxycarbonylmethyl-4-pyridinium group or N-alkyl-3,5-dimethyl-4-pyridinium group, still more preferably N-alkyl-3-pyridinium group or N-alkyl-4-pyridinium group, particularly preferably N-methyl-3-pyridinium group, N-octyl-3-pyridinium group, N-methyl-4-pyridinium group or N-octyl-4-pyridinium group, and most preferably N-octyl-3-pyridinium group or N-octyl-4-pyridinium group.

[0606] Also, when R 23 is a pyridinium group, as the counter anion, sulfonate ion, carboxylate ion, tetrafluoroborate ion, hexafluorophosphate ion, p-toluenesulfonate ion, perchlorate ion, etc. can be mentioned, and p-toluenesulfonate ion or hexafluorophosphate ion is preferred.

[0607] From the viewpoint of color rendering property, R in formula (1-4) 20 is preferably an alkyl group or an aryl group, and more preferably one of the two Rs 20 is an alkyl group and the other is an aryl group. The above two Rs 20 may be linked to form a ring.

[0608] From the viewpoint of color rendering property, R in formula (1-5) 20 is preferably an alkyl group or an aryl group, more preferably an aryl group, and still more preferably a p-methylphenyl group.

[0609] From the viewpoint of color rendering property, R in formula (1-6) 20 is each independently preferably an alkyl group or an aryl group, and more preferably a methyl group or a phenyl group.

[0610] From the viewpoint of color rendering properties, regarding Z in formula (1-7) 1 , any counterion for neutralizing the charge may be used, and it may also be included in the above-mentioned Za as a whole compound.

[0611] Z 1 Sulfonate ion, carboxylate ion, tetrafluoroborate ion, hexafluorophosphate ion, p-toluenesulfonate ion or perchlorate ion is preferred, and p-toluenesulfonate ion or hexafluorophosphate ion is more preferred.

[0612] When L is an oxygen atom in formula 1-1 or formula 1-A, from the viewpoint of color rendering properties, R 1 is further preferably a group represented by the following formula (5).

[0613] [Chemical formula 39]

[0614]

[0615] In formula (5), R 15 and R 16 each independently represent a hydrogen atom, an alkyl group or an aryl group, E represents an onium group, and * represents the bonding site with the oxygen atom represented by L in formula 1-1 or formula 1-A.

[0616] The alkyl group represented by R 15 or R 16 is the same as the alkyl groups of R 2 ~R 9 and R 0 , and the preferred mode is also the same as the preferred mode of the alkyl groups of R 2 ~R 9 and R 0 .

[0617] The aryl group represented by R 15 or R 16 is the same as the aryl group of R 0 , and the preferred mode is also the same as the preferred mode of the aryl group of R 0 .

[0618] The onium group represented by E is the same as the onium group of R 23 , and the preferred mode is also the same as the preferred mode of the onium group of R 23 .

[0619] In formula (5), the onium group represented by E is preferably a pyridinium group represented by the following formula (6).

[0620] [Chemical formula 40]

[0621]

[0622] In formula (6), R17 represents a halogen atom, an alkyl group, an aryl group, a hydroxyl group or an alkoxy group. In the case where there are multiple Rs 17 , the multiple Rs 17 may be the same or different, or multiple Rs 17 may be connected to form a ring. n2 represents an integer from 0 to 4. R 18 represents an alkyl group or an aryl group. Z b represents a counter ion for neutralizing charge.

[0623] The alkyl group or aryl group represented by R 17 or R 18 is the same as the alkyl group or aryl group in R 2 ~R 9 and R 0 , and the preferred mode is also the same as the preferred mode of the alkyl group in R 0 or the aryl group in R 2 ~R 9 and R 0 . 0 The alkoxy group represented by R

[0624] is preferably an alkoxy group having 1 to 10 carbon atoms, and examples thereof include methoxy group, ethoxy group, n-propoxy group, isopropoxy group, n-butoxy group, isobutoxy group, tert-butoxy group and the like. 17 n2 is preferably 0.

[0625] The counter ion for neutralizing charge represented by Z

[0626] is the same as Z in formula (1-7), and the preferred mode is also the same as the preferred mode of Z b in formula (1-7). 1 1 1 The preferred mode of 1

[0627] Hereinafter, in the case where L in formula 1-1 or formula 1-A is an oxygen atom, specific examples of the group represented by R 1 are given, but the present invention is not limited to these. In the following structural formulas, TsO - represents a p-toluenesulfonate anion, and ● represents the bonding site of the oxygen atom represented by L in formula 1-1 or formula 1-A.

[0628] [Chemical formula 41]

[0629]

[0630] [Chemical formula 42]

[0631]

[0632] [Chemical formula 43]

[0633]

[0634] [Chemical Formula 44]

[0635]

[0636] [Chemical Formula 45]

[0637]

[0638] [Chemical Formula 46]

[0639]

[0640] [Chemical Formula 47]

[0641]

[0642] [Chemical Formula 48]

[0643]

[0644] [Chemical Formula 49]

[0645]

[0646] When L is an oxygen atom, R 1 being an aryl group or a linear alkyl group will not cause the cleavage of the R 1 -O bond due to infrared exposure.

[0647] When L is a sulfur atom in Formula 1-1 or Formula 1-A, R 1 is preferably a group represented by the following formula (2-1).

[0648] [Chemical Formula 50]

[0649]

[0650] In formula (2-1), ● represents the bonding site to the sulfur atom represented by L in Formula 1-1 or Formula 1-A, and R 21 each independently represents a hydrogen atom, an alkyl group or an aryl group, and R 22 represents an aryl group, an alkenyl group, an alkoxy group or an oxonium group.

[0651] When L is -NR 10 - in Formula 1-1 or Formula 1-A, the R 1 bonded to N is preferably a group represented by the following formula (3-1).

[0652] [Chemical Formula 51]

[0653]

[0654] In formula (3-1), ● represents the bonding site with the nitrogen atom contained in L in formula 1-1 or formula 1-A, and X 1 and X 2 each independently represents an oxygen atom or a sulfur atom, and Y represents a group represented by the above formula (2-1).

[0655] In the above formula (2-1), regarding the alkyl group, aryl group, alkenyl group, alkoxy group, and oxonium group represented by R 21 and R 22 , the descriptions related to the alkyl group, aryl group, alkenyl group, alkoxy group, and oxonium group described in the above formulas (1-1) to (1-7) can be cited.

[0656] In formula 1-1 or formula 1-A, from the viewpoint of improving printing durability, it is preferred that L represents a sulfur atom or -NR 10 -, and R 10 represents a hydrogen atom, an alkyl group, or an aryl group.

[0657] R 1 in the above formulas 1-1 and 1-A is preferably a group represented by the following formula 2.

[0658] Moreover, the group represented by the above formula 2 is preferably a group in which the R Z -O bond in formula 2 is broken by infrared exposure.

[0659] [Chemical formula 52]

[0660]

[0661] In formula 2, R Z represents an alkyl group, and the wavy line part represents the bonding site with the group represented by L in formula 1-1 or formula 1-A.

[0662] As the alkyl group represented by R Z , it is the same as the preferred mode of the alkyl group in the above R 2 ~R 9 and R 0 .

[0663] From the viewpoints of color rendering property and UV printing durability of the obtained lithographic printing plate, as the above alkyl group, a secondary alkyl group or a tertiary alkyl group is preferred, and a tertiary alkyl group is more preferred.

[0664] Moreover, from the viewpoints of color rendering property and UV printing durability of the obtained lithographic printing plate, as the above alkyl group, an alkyl group having 1 to 8 carbon atoms is preferred, a branched alkyl group having 3 to 10 carbon atoms is more preferred, a branched alkyl group having 3 to 6 carbon atoms is further preferred, isopropyl or tert-butyl is particularly preferred, and tert-butyl is most preferred.

[0665] Hereinafter, specific examples of the group represented by the above formula (2) are given, but the present invention is not limited to these. In the following structural formulas, ● represents the bonding site to L in formula (1-1) or formula (1-A).

[0666] [Chemical formula 53]

[0667]

[0668] Hereinafter, specific examples of the infrared absorber that decomposes by infrared exposure are given, but the present invention is not limited to these.

[0669] [Chemical formula 54]

[0670]

[0671] [Chemical formula 55]

[0672]

[0673] [Chemical formula 56]

[0674]

[0675] Moreover, as the infrared absorber that decomposes by infrared exposure, the infrared absorbers described in Japanese Patent Application Laid-Open No. 2008-544322 or International Publication No. 2016 / 027886 can be preferably used.

[0676] Only one kind of infrared absorber may be used, or two or more kinds may be used simultaneously. Moreover, as the infrared absorber, a pigment and a dye can be used simultaneously.

[0677] The content of the infrared absorber in the above 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, based on the total mass of the image recording layer.

[0678] [Relationship among electron-donating polymerization initiator, electron-accepting polymerization initiator, and infrared absorber]

[0679] The image recording layer in the present invention contains the above electron-donating polymerization initiator, the above electron-accepting polymerization initiator, and the above infrared absorber. Preferably, the HOMO of the above electron-donating polymerization initiator is -6.0 eV or more, and the LUMO of the above electron-accepting polymerization initiator is -3.0 eV or less.

[0680] More preferred modes of the HOMO of the above electron-donating polymerization initiator and the LUMO of the above electron-accepting polymerization initiator are as described above.

[0681] It is speculated that in the image recording layer of the present invention, energy transfer occurs among the above-mentioned electron-donating polymerization initiator, the above-mentioned infrared absorber, and the above-mentioned electron-accepting polymerization initiator as described in the following chemical formula.

[0682] Therefore, it is considered that if the HOMO of the above-mentioned electron-donating polymerization initiator is -6.0 eV or more and the LUMO of the above-mentioned electron-accepting polymerization initiator is -3.0 eV or less, the generation efficiency of free radicals is improved, and thus it is easier to make the chemical resistance and UV printing durability more excellent.

[0683] [Chemical formula 57]

[0684]

[0685] From the viewpoints of UV printing durability and chemical resistance, the value of HOMO of the above-mentioned infrared absorber - HOMO of the above-mentioned electron-donating polymerization initiator is preferably 1.00 eV or less, more preferably 0.700 eV or less. And from the same viewpoints, the value of HOMO of the above-mentioned infrared absorber - HOMO of the above-mentioned electron-donating polymerization initiator is preferably -0.200 eV or more, more preferably -0.100 eV or more.

[0686] And from the same viewpoints, the value of HOMO of the above-mentioned infrared absorber - HOMO of the above-mentioned electron-donating polymerization initiator is preferably from 1.00 eV to -0.200 eV, more preferably from 0.700 eV to -0.100 eV. In addition, a negative value means that the HOMO of the above-mentioned electron-donating polymerization initiator is higher than the HOMO of the above-mentioned infrared absorber.

[0687] And from the viewpoints of UV printing durability and chemical resistance, the value of LUMO of the above-mentioned electron-accepting polymerization initiator - LUMO of the above-mentioned infrared absorber is preferably 1.00 eV or less, more preferably 0.700 eV or less. And from the same viewpoints, the value of LUMO of the above-mentioned electron-accepting polymerization initiator - LUMO of the above-mentioned infrared absorber is preferably -0.200 eV or more, more preferably -0.100 eV or more.

[0688] And from the same viewpoints, the value of LUMO of the above-mentioned electron-accepting polymerization initiator - LUMO of the above-mentioned infrared absorber is preferably from 1.00 eV to -0.200 eV, more preferably from 0.700 eV to -0.100 eV. In addition, a negative value means that the LUMO of the above-mentioned infrared absorber is higher than the LUMO of the above-mentioned electron-accepting polymerization initiator.

[0689] -Particle-

[0690] From the viewpoint of UV printing durability, the above-mentioned image recording layer preferably contains particles.

[0691] As the particles, they can be organic particles or inorganic particles. However, from the viewpoint of the durability of UV printing, organic particles are preferably included, and polymer particles are more preferably included.

[0692] As the inorganic particles, known inorganic particles can be used, and metal oxide particles such as silica particles and titanium dioxide particles can be preferably used.

[0693] The polymer particles are preferably selected from the group consisting of thermoplastic resin particles, thermoreactive resin particles, polymer particles having a polymerizable group, microcapsules containing a hydrophobic compound, and microgels (crosslinked polymer particles). Among them, polymer particles having a polymerizable group or microgels are preferred. In a particularly preferred embodiment, the polymer particles contain at least one ethylenically unsaturated polymerizable group. Due to the presence of such polymer particles, the effects of improving the printing durability of the exposed portion and the on-machine developability of the unexposed portion can be obtained.

[0694] Furthermore, from the viewpoints of the durability of UV printing and the on-machine developability, the polymer particles are preferably thermoplastic resin particles.

[0695] As the thermoplastic resin particles, the thermoplastic polymer particles described in Research Disclosure No. 33303 in January 1992, Japanese Patent Laid-Open No. 9-123387, Japanese Patent Laid-Open No. 9-131850, Japanese Patent Laid-Open No. 9-171249, Japanese Patent Laid-Open No. 9-171250, and European Patent No. 931647 specification, etc. are preferred.

[0696] Specific examples of the polymer constituting the thermoplastic resin particles include homopolymers or prepolymers of monomers such as ethylene, styrene, vinyl chloride, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, vinylidene chloride, acrylonitrile, vinyl carbazole, and acrylates or methacrylates having a polyalkylene structure, or mixtures thereof. Polystyrene, copolymers of styrene and acrylonitrile, or polymethyl methacrylate can be preferably selected. The average particle diameter of the thermoplastic resin particles is preferably 0.01 μm to 3.0 μm.

[0697] As the thermoreactive resin particles, polymer particles having a thermoreactive group can be cited. The thermoreactive polymer particles form a hydrophobic region through crosslinking based on a thermal reaction and a change in functional groups during crosslinking.

[0698] As the heat-reactive group in the polymer particles having a heat-reactive group, as long as it can form a chemical bond, it can be a functional group that undergoes any reaction, but a polymerizable group is preferred. As an example thereof, an ethylenically unsaturated group (e.g., acryloyl, methacryloyl, vinyl, allyl, etc.) that undergoes a radical polymerization reaction, a cationic polymerizable group (e.g., vinyl, vinyloxy, epoxy group, oxetanyl, etc.), an isocyanate group or a block thereof that undergoes an addition reaction, an epoxy group, a vinyloxy group, and a functional group having an active hydrogen atom as a reaction target thereof (e.g., amino group, hydroxyl group, carboxyl group, etc.), a carboxyl group that undergoes a condensation reaction and a hydroxyl group or an amino group as a reaction target, an acid anhydride that undergoes a ring-opening addition reaction and an amino group or a hydroxyl group as a reaction target, etc. are preferably selected.

[0699] As the microcapsules, for example, as described in JP-A-2001-277740 and JP-A-2001-277742, microcapsules containing at least a part of the constituent components of the image recording layer inside the microcapsules. The constituent components of the image recording layer may also be contained outside the microcapsules. The image recording layer containing the microcapsules preferably has a structure in which a hydrophobic constituent component is contained inside the microcapsules and a hydrophilic constituent component is contained outside the microcapsules.

[0700] The microgel (crosslinked polymer particles) can contain a part of the constituent components of the image recording layer on at least one of its surface and inside. In particular, from the viewpoints of the sensitivity of the obtained original lithographic printing plate and the printing durability of the obtained lithographic printing plate, a reactive microgel having a radical polymerizable group on its surface is preferred.

[0701] In order to microencapsulate or microgelate the constituent components of the present image recording layer, known methods can be applied.

[0702] And, as the polymer particles, from the viewpoints of the printing durability, antifouling property, and storage stability of the obtained lithographic printing plate, polymer particles obtained by the reaction of a polyisocyanate compound that is an adduct of a polyphenol compound having two or more hydroxyl groups in the molecule and isophorone diisocyanate and a compound having an active hydrogen are preferred.

[0703] As the above-mentioned polyphenol compound, a compound having a plurality of benzene rings having phenolic hydroxyl groups is preferred.

[0704] As the compound having the above-mentioned active hydrogen, a polyol compound or a polyamine compound is preferred, a polyol compound is more preferred, and at least one compound selected from the group consisting of propylene glycol, glycerin, and trimethylolpropane is further preferred.

[0705] As the particles of the resin obtained by the reaction of a polyisocyanate compound, which is an adduct of a polyhydric phenol compound having two or more hydroxyl groups in the molecule and isophorone diisocyanate, and a compound having an active hydrogen, the polymer particles described in paragraphs 0032 to 0095 of Japanese Patent Application Laid-Open No. 2012-206495 are preferably selected.

[0706] Moreover, as the polymer particles, from the viewpoints of the printing durability and solvent resistance of the obtained lithographic printing plate, those having a hydrophobic main chain and containing both i) a structural unit having a side cyano group directly bonded to the hydrophobic main chain and ii) a structural unit having a side group containing a hydrophilic polyalkylene oxide chain segment are preferred.

[0707] As the hydrophobic main chain, an acrylic resin chain is preferably selected.

[0708] As examples of the side cyano group, -[CH2CH(C≡N)]- or -[CH2C(CH3)(C≡N)]- is preferably selected.

[0709] Furthermore, the structural unit having the side cyano group can be easily derived from an ethylenically unsaturated monomer, such as acrylonitrile or methacrylonitrile, or a combination thereof.

[0710] Moreover, as the alkylene oxide in the hydrophilic polyalkylene oxide chain segment, ethylene oxide or propylene oxide is preferred, and ethylene oxide is more preferred.

[0711] The number of repetitions of the alkylene oxide structure in the hydrophilic polyalkylene oxide chain segment is preferably 10 to 100, more preferably 25 to 75, and still more preferably 40 to 50.

[0712] As the particles of the resin having a hydrophobic main chain and containing both i) a structural unit having a side cyano group directly bonded to the hydrophobic main chain and ii) a structural unit having a side group containing a hydrophilic polyalkylene oxide chain segment, the particles described in paragraphs 0039 to 0068 of Japanese Patent Application Laid-Open No. 2008-503365 are preferably selected.

[0713] Furthermore, from the viewpoints of UV printing durability and on-press developability, the polymer particles preferably have a hydrophilic group.

[0714] As the hydrophilic group, if it has a hydrophilic structure, there is no particular limitation, but acid groups such as carboxyl group, hydroxyl group, amino group, cyano group, polyalkylene oxide structure, etc. can be mentioned.

[0715] Among them, from the viewpoints of on-press developability and UV 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.

[0716] Further, from the viewpoints of in-machine developability and suppression of development residues during in-machine development, as the above polyalkylene oxide structure, a polypropylene oxide structure is preferred, and a polyethylene oxide structure and a polypropylene oxide structure are more preferred.

[0717] Further, as the above hydrophilic group, from the viewpoints of printing durability, ink-attachability, and in-machine developability, a structural unit having a cyano group or a group represented by the following formula Z is preferably included, a structural unit represented by the following formula (AN) or a group represented by the following formula Z is more preferably included, and a group represented by the following formula Z is particularly preferably included.

[0718] *-Q-W-Y Formula Z

[0719] 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, any one of W and Y has a hydrophilic structure, and * represents a bonding site to another structure.

[0720] [Chemical formula 58]

[0721]

[0722] In formula (AN), R AN represents a hydrogen atom or a methyl group.

[0723] From the viewpoint of UV printing durability, the polymer contained in the above polymer particles preferably contains a structural unit formed from a compound having a cyano group.

[0724] For the cyano group, a compound (monomer) having a cyano group is usually preferably introduced into the resin as a structural unit containing a cyano group. As the compound having a cyano group, an acrylonitrile compound can be cited, and (meth)acrylonitrile is preferably cited.

[0725] As the structural unit having a cyano group, a structural unit formed from an acrylonitrile compound is preferred, and a structural unit formed from (meth)acrylonitrile, that is, a structural unit represented by the above formula (AN), is more preferred.

[0726] When the above polymer contains a polymer having a structural unit having a cyano group, from the viewpoint of UV printing durability, relative to the total mass of the polymer having a structural unit having a cyano group, the content of the structural unit having a cyano group in the polymer having a structural unit having a cyano group, preferably a structural unit represented by the above formula (AN), is preferably 5% by mass to 90% by mass, more preferably 20% by mass to 80% by mass, and particularly preferably 30% by mass to 60% by mass.

[0727] Further, from the viewpoints of printing durability, ink receptivity, and on-machine developability, the above polymer particles preferably include polymer particles having a group represented by the above formula Z.

[0728] In the formula Z above, Q is preferably a divalent linking group having 1 to 20 carbon atoms, more preferably a divalent linking group having 1 to 10 carbon atoms.

[0729] Further, Q in the formula Z above is preferably an alkylene group, an arylene group, an ester bond, an amide bond, or a group obtained by combining two or more of them, more preferably a phenylene group, an ester bond, or an amide bond.

[0730] The divalent group having a hydrophilic structure in W of the formula Z above is preferably a polyalkyleneoxy group or a group in which -CH2CH2NR W - is bonded to one end of the polyalkyleneoxy group. Further, R W represents a hydrogen atom or an alkyl group.

[0731] The divalent group having a hydrophobic structure in W of the formula Z above is preferably -R WA -, -O-R WA -O-, -R W N-R WA -NR W -, -OC(=O)-R WA -O- or -OC(=O)-R WA -O-. Further, R 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 alkarylene group (a divalent group obtained by removing one hydrogen atom from an alkyl aryl group) having 6 to 120 carbon atoms, or an aralkyl group having 6 to 120 carbon atoms.

[0732] The monovalent group having a hydrophilic structure in Y of the formula Z above is preferably -OH, -C(=O)OH, a polyalkyleneoxy group having a hydrogen atom or an alkyl group at the end, or a group in which -CH2CH2N(R W )- is bonded to the other end of the polyalkyleneoxy group having a hydrogen atom or an alkyl group at the end.

[0733] The monovalent group having a hydrophobic structure in Y of the formula Z above 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 (alkyl aryl group) having 6 to 120 carbon atoms, an aralkyl group having 6 to 120 carbon atoms, -OR WB , -C(=O)OR WB or -OC(=O)R WB . RWB represents an alkyl group having 6 to 20 carbon atoms.

[0734] Among the polymer particles having the group represented by the above formula Z, from the viewpoints of printing durability, ink receptivity, and on-machine developability, it is more preferable that W is a divalent group having a hydrophilic structure, more preferably Q is a phenylene group, an ester bond, or an amide bond, W is a polyalkyleneoxy group, and Y is a polyalkyleneoxy group having a hydrogen atom or an alkyl group at the terminal.

[0735] Moreover, from the viewpoints of printing durability and on-machine developability, the above polymer particles preferably include polymer particles having a polymerizable group, and more preferably include polymer particles having a polymerizable group on the particle surface.

[0736] Furthermore, from the viewpoint of printing durability, the above polymer particles preferably include polymer particles having a hydrophilic group and a polymerizable group.

[0737] The above polymerizable group may be a cationic polymerizable group or a radical polymerizable group, but from the viewpoint of reactivity, a radical polymerizable group is preferred.

[0738] As the above polymerizable group, as long as it is a group capable of polymerization, there is no particular limitation, but from the viewpoint of reactivity, an ethylenically unsaturated group is preferred, more preferably a vinylphenyl (styryl) group, a (meth)acryloyloxy group, or a (meth)acrylamide group, and particularly preferably a (meth)acryloyloxy group.

[0739] Moreover, the polymer in the polymer particles having a polymerizable group preferably has a structural unit having a polymerizable group.

[0740] Furthermore, a polymerizable group can be introduced onto the surface of the polymer particles by a polymer reaction.

[0741] Moreover, from the viewpoints of UV printing durability and on-machine developability, the above image recording layer preferably includes addition-polymerizable resin particles having a dispersibility group as the above polymer particles, and more preferably the above dispersibility group includes the group represented by the above formula Z.

[0742] Furthermore, from the viewpoints of printing durability, ink receptivity, on-machine developability, and suppression of developing residues during on-machine development, the above polymer particles preferably include a resin having a urea bond, more preferably include a resin having at least a structure obtained by reacting the isocyanate compound represented by the following formula (Iso) with water, and particularly preferably include a resin having at least a structure obtained by reacting the isocyanate compound represented by the following formula (Iso) with water, and having a polyethylene oxide structure and a polypropylene oxide structure as a polyalkylene oxide structure. And the particles containing the resin having the above urea bond are preferably microgels.

[0743] [Chemical Formula 59]

[0744]

[0745] In formula (Iso), n represents an integer from 0 to 10.

[0746] As an example of the reaction of the isocyanate compound represented by the above formula (Iso) with water, the reaction shown below can be cited. In addition, the following example is an example where n = 0 and the 4,4-isomer is used.

[0747] As shown below, when the isocyanate compound represented by the above formula (Iso) reacts with water, amino groups are generated by hydrolysis of a part of the water isocyanate groups, and the generated amino groups react with the isocyanate groups to form urea bonds and form dimers. And the following reaction is repeated to form a resin having urea bonds.

[0748] Furthermore, in the following reaction, by adding a compound having reactivity with the isocyanate group such as an alcohol compound or an amine compound (a compound having active hydrogen), the structures of the alcohol compound, the amine compound, etc. can also be introduced into the resin having urea bonds.

[0749] As the above compound having active hydrogen, the compounds described in the above microgel are preferably selected.

[0750] [Chemical Formula 60]

[0751]

[0752] Furthermore, the resin having the above urea bonds preferably has an ethylenically unsaturated group, and more preferably has a group represented by the following formula (PETA).

[0753] [Chemical Formula 61]

[0754]

[0755] In formula (PETA), the wavy line part represents the bonding position to other structures.

[0756] Furthermore, from the viewpoints of UV printing durability and on-machine developability, the above image recording layer preferably contains thermoplastic resin particles.

[0757] The thermoplastic resin contained in the thermoplastic resin particles is not particularly limited. For example, polyethylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, poly(methyl)acrylate, poly(ethyl)acrylate, poly(butyl)acrylate, polyacrylonitrile, polyvinyl acetate, copolymers thereof, etc. can be cited. The thermoplastic resin can be in a latex state.

[0758] The thermoplastic resin involved in the present invention is preferably a resin that forms part or all of a hydrophobic film for forming a recording layer by melting or softening the thermoplastic resin with heat generated in the exposure process described below.

[0759] As the above-mentioned thermoplastic resin, from the viewpoints of ink inkability and UV printing durability, a resin A containing a structural unit formed from an aromatic vinyl compound and a structural unit having a cyano group is preferred.

[0760] The resin A contained in the thermoplastic resin preferably has a structural unit formed from an aromatic vinyl compound.

[0761] As the aromatic vinyl compound, any compound having a structure in which a vinyl group is bonded to an aromatic ring may be used, and examples thereof include styrene compounds and vinylnaphthalene compounds. Styrene compounds are preferred, and styrene is more preferred.

[0762] As the styrene compound, styrene, p-methylstyrene, p-methoxystyrene, β-methylstyrene, p-methyl-β-methylstyrene, α-methylstyrene, and p-methoxy-β-methylstyrene may be mentioned, and styrene is preferably selected.

[0763] As the vinylnaphthalene compound, 1-vinylnaphthalene, methyl-1-vinylnaphthalene, β-methyl-1-vinylnaphthalene, 4-methyl-1-vinylnaphthalene, 4-methoxy-1-vinylnaphthalene, etc. may be mentioned, and 1-vinylnaphthalene is preferably selected.

[0764] Moreover, as the structural unit formed from an aromatic vinyl compound, the structural unit represented by the following formula A1 is preferably selected.

[0765] [Chemical formula 62]

[0766]

[0767] 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 of Ar.

[0768] In formula A1, R 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 still more preferably both are hydrogen atoms.

[0769] In formula A1, Ar is preferably a benzene ring or a naphthalene ring, and more preferably a benzene ring.

[0770] In formula A1, R A3Preferably 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, still more preferably a methyl group or a methoxy group.

[0771] In formula A1, when there are multiple Rs A3 the multiple Rs A3 may be the same or may be different from each other.

[0772] In formula A1, n is preferably an integer of 0 to 2, more preferably 0 or 1, still more preferably 0.

[0773] In resin A contained in the thermoplastic resin, from the viewpoint of ink adhesion property, the content of the structural unit formed from an aromatic vinyl compound is preferably more than the content of the structural unit having a cyano group described later, and is more preferably 15% by mass to 85% by mass, still more preferably 30% by mass to 70% by mass, based on the total mass of the thermoplastic resin.

[0774] Resin A contained in the thermoplastic resin particles preferably contains a structural unit having a cyano group.

[0775] The cyano group is usually preferably introduced into resin A as a structural unit containing a cyano group using a compound (monomer) having a cyano group. Examples of the compound having a cyano group include acrylonitrile compounds, and (meth)acrylonitrile is preferably selected.

[0776] As the structural unit having a cyano group, a structural unit formed from an acrylonitrile compound is preferred, and a structural unit formed from (meth)acrylonitrile is more preferred.

[0777] Moreover, as the structural unit formed from a compound having a cyano group, a structural unit represented by the following formula B1 is preferably selected.

[0778] [Chemical formula 63]

[0779]

[0780] In formula B1, R B1 represents a hydrogen atom or an alkyl group.

[0781] In formula B1, R 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, still more preferably a hydrogen atom.

[0782] From the viewpoint of ink adhesion property, the content of the structural unit having a cyano group in resin A is preferably less than the content of the structural unit formed from the above aromatic vinyl compound, and is more preferably 55% by mass to 90% by mass, still more preferably 60% by mass to 85% by mass, based on the total mass of resin A.

[0783] Further, when the 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 an aromatic vinyl compound to the structural unit having a cyano group (structural unit formed from an aromatic vinyl compound: structural unit having a cyano group) is preferably 5:5 to 9:1, more preferably 6:4 to 8:2, on a mass basis.

[0784] From the viewpoints of UV printing durability and chemical resistance, the resin A contained in the thermoplastic resin particles preferably further has a structural unit formed from an N-vinyl heterocyclic compound.

[0785] 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.

[0786] Further, as the structural unit formed from an N-vinyl heterocyclic compound, a structural unit represented by the following formula C1 is preferably selected.

[0787] [Chemical formula 64]

[0788]

[0789] In formula C1, Ar N represents a heterocyclic structure containing a nitrogen atom, and the nitrogen atom in Ar N is bonded to the carbon atom represented by *.

[0790] In formula C1, the heterocyclic structure represented by Ar N 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, more preferably a pyrrolidone ring.

[0791] Further, the heterocyclic structure represented by Ar N may have known substituents.

[0792] The content of the structural unit formed from an N-vinyl heterocyclic compound in the resin A is preferably 5% by mass to 50% by mass, more preferably 10% by mass to 40% by mass, relative to the total mass of the resin A.

[0793] The resin A contained in the thermoplastic resin particles may contain a structural unit having an acidic group, but preferably does not contain a structural unit having an acidic group, from the viewpoints of on-machine developability and ink inkability.

[0794] 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 still more preferably 5% by mass or less. The lower limit of the above content is not particularly limited and may be 0% by mass.

[0795] Moreover, the acid value of the thermoplastic resin is preferably 160 mgKOH / g or less, more preferably 80 mgKOH / g or less, and still more preferably 40 mgKOH / g or less. The lower limit of the above acid value is not particularly limited and may be 0 mgKOH / g.

[0796] In the present invention, the acid value is determined by a method in accordance with JIS K0070:1992.

[0797] From the viewpoint of ink inkability, the resin A contained in the thermoplastic resin particles may contain a structural unit containing a hydrophobic group.

[0798] Examples of the above hydrophobic group include an alkyl group, an aryl group, and an aralkyl group.

[0799] As the structural unit containing a hydrophobic group, a structural unit formed from an (alkyl)acrylic acid alkyl ester compound, an (alkyl)acrylic acid aryl ester compound, or an (alkyl)acrylic acid aralkyl ester compound is preferred, and a structural unit formed from an (alkyl)acrylic acid alkyl ester compound is more preferred.

[0800] The number of carbon atoms of the alkyl group in the above (alkyl)acrylic acid alkyl ester compound is preferably 1 to 10. The alkyl group may be linear, branched, or may have a cyclic structure. Examples of the (alkyl)acrylic acid alkyl ester compound include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, dicyclopentyl (meth)acrylate, and the like.

[0801] The number of carbon atoms of the aryl group in the above (alkyl)acrylic acid aryl ester compound is preferably 6 to 20, and more preferably a phenyl group. Moreover, the above aryl group may have a known substituent. Examples of the (alkyl)acrylic acid aryl ester compound preferably include phenyl (meth)acrylate.

[0802] The number of carbon atoms of the alkyl group in the above (alkyl)acrylic acid aralkyl ester compound is preferably 1 to 10. The alkyl group may be linear, branched, or may have a cyclic structure. Moreover, the number of carbon atoms of the aryl group in the above (alkyl)acrylic acid aralkyl ester compound is preferably 6 to 20, and more preferably a phenyl group. Examples of the (alkyl)acrylic acid aralkyl ester compound preferably include benzyl (meth)acrylate.

[0803] The content of the structural unit having a hydrophobic group in Resin A contained in the thermoplastic resin particles is preferably 5% by mass to 50% by mass, more preferably 10% by mass to 30% by mass, relative to the total mass of Resin A.

[0804] From the viewpoints of UV printing durability and on-machine developability, the thermoplastic resin contained in the above thermoplastic resin particles preferably has a hydrophilic group.

[0805] As the hydrophilic group, if it has a hydrophilic structure, there is no particular limitation, but acid groups such as carboxyl group, hydroxyl group, amino group, cyano group, polyalkylene oxide structure, etc. can be mentioned.

[0806] As the above hydrophilic group, from the viewpoints of UV printing durability and on-machine developability, a group having a polyalkylene oxide structure, a group having a polyester structure or a sulfonic acid group is preferred, a group having a polyalkylene oxide structure or a sulfonic acid group is more preferred, and a group having a polyalkylene oxide structure is further preferred.

[0807] As the above polyalkylene oxide structure, from the viewpoint of on-machine developability, a polyethylene oxide structure, a polypropylene oxide structure or a poly(ethylene oxide / propylene oxide) structure is preferred.

[0808] Moreover, from the viewpoint of on-machine developability, among the above hydrophilic groups, as the polyalkylene oxide structure, a polypropylene oxide structure is preferred, and a polyethylene oxide structure and a polypropylene oxide structure are more preferred.

[0809] From the viewpoint of on-machine developability, the number of alkylene oxide structures in the above polyalkylene oxide structure is preferably 2 or more, more preferably 5 or more, further preferably 5 to 200, and particularly preferably 8 to 150.

[0810] Moreover, from the viewpoint of on-machine developability, as the above hydrophilic group, a group represented by the above formula Z is preferred.

[0811] From the viewpoints of improving UV printing durability, chemical resistance and on-machine developability, Resin A contained in the thermoplastic resin particles preferably contains a structural unit having a hydrophilic group.

[0812] As the above hydrophilic group, -OH, -CN, -CONR 1 R 2 、-NR 2 COR 1 (R 1 and R 2 each independently represent a hydrogen atom, an alkyl group, an alkenyl group or an aryl group. R 1 and R 2 may be bonded to form a ring.)-NR 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, and X - represents a counter anion), a group represented by the following formula PO, a hydrophilic group that the thermoplastic resin contained in the thermoplastic resin particles preferably has, and the like.

[0813] Among these hydrophilic groups, -CONR 1 R 2 or a group represented by the formula PO is preferred, and a group represented by the formula PO is more preferred.

[0814] [Chemical formula 65]

[0815]

[0816] 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.

[0817] In the formula PO, L P is each independently preferably an ethylene group, 1-methylethylene group or 2-methylethylene group, and more preferably an ethylene group.

[0818] In the formula PO, R 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, further preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and particularly preferably a hydrogen atom or a methyl group.

[0819] In the formula PO, n is preferably an integer of 1 to 10, and more preferably an integer of 1 to 4.

[0820] Relative to the total mass of Resin A, the content of the structural unit having a hydrophilic group in Resin A is preferably 5% by mass to 60% by mass, and more preferably 10% by mass to 30% by mass.

[0821] The Resin A contained in the thermoplastic resin particles may further contain other structural units. As the other structural units, structural units other than the above-mentioned respective structural units can be contained without particular limitation. For example, structural units formed from acrylamide compounds, vinyl ether compounds, etc. can be cited.

[0822] As the acrylamide compound, for example, (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, N-hydroxybutyl(meth)acrylamide, etc. can be cited.

[0823] As the vinyl ether compound, for example, 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 mono vinyl ether, polyethylene glycol vinyl ether, chloroethyl vinyl ether, chlorobutyl vinyl ether, chloroethoxyethyl vinyl ether, phenylethyl vinyl ether, phenoxypolyethylene glycol vinyl ether, etc. can be cited.

[0824] The content of other structural units in the thermoplastic resin is preferably 5% by mass to 50% by mass, more preferably 10% by mass to 30% by mass, based on the total mass of the thermoplastic resin.

[0825] From the viewpoints of UV printing durability and ink inkability, the glass transition temperature (Tg) of the thermoplastic resin is preferably 60°C to 150°C, more preferably 80°C to 140°C, and further preferably 90°C to 130°C.

[0826] When the thermoplastic resin particles contain two or more thermoplastic resins, the value obtained by the FOX formula described later is referred to as the glass transition temperature of the thermoplastic resin.

[0827] In the present invention, the glass transition temperature of the resin can be measured by differential scanning calorimetry (DSC).

[0828] The specific measurement method is carried out in accordance with the methods described in JIS K 7121 (1987) or JIS K 6240 (2011). The glass transition temperature in this specification uses the extrapolated glass transition start temperature (hereinafter, sometimes referred to as Tig).

[0829] The method for measuring the glass transition temperature will be described in more detail.

[0830] When determining the glass transition temperature, after the apparatus is stabilized at a temperature about 50 °C lower than the predicted Tg of the resin, it is heated at a heating rate of 20 °C / minute to a temperature about 30 °C higher than the temperature at which the glass transition ends, and a differential thermal analysis (DTA) curve or a DSC curve is plotted.

[0831] Regarding the extrapolated glass transition start temperature (Tig), which is the glass transition temperature Tg in this specification, it is determined as the temperature of the intersection point of the straight line obtained by extending the low-temperature side baseline to the high-temperature side in the DTA curve or the DSC curve and the tangent line drawn at the point where the gradient of the curve in the stepped change portion of the glass transition becomes the maximum.

[0832] When the thermoplastic resin particles contain two or more thermoplastic resins, the Tg of the thermoplastic resins contained in the thermoplastic resin particles is determined as follows.

[0833] When the Tg of the first thermoplastic resin is set as 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 set as W1, the second Tg is set as 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 set as W2, the Tg0 (K) of the thermoplastic resin particles can be inferred according to the following FOX equation.

[0834] FOX equation: 1 / Tg0 = (W1 / Tg1) + (W2 / Tg2)

[0835] Furthermore, when the thermoplastic resin particles contain three resins, or when the pretreatment liquid contains three kinds of thermoplastic resin particles with different types of thermoplastic resins contained therein, regarding the Tg of the thermoplastic resin particles, when the Tg of the nth resin is set as 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 set as Wn, it can be inferred in the same manner as above according to the following formula.

[0836] FOX equation: 1 / Tg0 = (W1 / Tg1) + (W2 / Tg2) + (W3 / Tg3) …… + (Wn / Tgn)

[0837] In this specification, Tg is a value measured by a differential scanning calorimeter (DSC: Differential scanning calorimeter). As the differential scanning calorimeter (DSC), for example, EXSTAR6220 of Seiko Instruments Inc. can be used.

[0838] From the viewpoint of the durability of UV printing, the arithmetic mean particle diameter 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 still more preferably 10 nm or more and 49 nm or less.

[0839] Regarding the arithmetic mean particle diameter of the thermoplastic resin particles in the present invention, unless otherwise specified, it refers to the value measured by the dynamic light scattering method (DLS). Regarding the measurement of the arithmetic mean particle diameter of the thermoplastic resin particles based on DLS, Brookhaven BI-90 (manufactured by Brookhaven Instrument Company) is used and carried out according to the above equipment manual.

[0840] The weight average molecular weight of the thermoplastic resin contained in the thermoplastic resin particles is preferably 3,000 to 300,000, more preferably 5,000 to 100,000.

[0841] The method for producing the thermoplastic resin contained in the thermoplastic resin particles is not particularly limited and can be produced by a known method.

[0842] For example, it is obtained by polymerizing a styrene compound, an acrylonitrile compound, and at least one compound selected from the group consisting of the above-mentioned N-vinyl heterocyclic compound, the compound used in the formation of the above-mentioned structural unit having an ethylenically unsaturated group, the compound used in the formation of the above-mentioned structural unit having an acidic group, the compound used in the formation of the above-mentioned structural unit having a hydrophobic group, and the compound used in the formation of the above-mentioned other structural unit by a known method.

[0843] Specific examples of the thermoplastic resin contained in the thermoplastic resin particles are shown in the following table, but the thermoplastic resin used in the present invention is not limited to these.

[0844] [Chemical formula 66]

[0845]

[0846] [Chemical formula 67]

[0847]

[0848] Moreover, in the above specific examples, the content ratio of each structural unit can be appropriately changed according to the preferred range of the content of each structural unit.

[0849] Moreover, the weight average molecular weight of each compound shown in the above specific examples can be appropriately changed according to the preferred range of the weight average molecular weight of the thermoplastic resin.

[0850] The average particle diameter of the above-mentioned particles is preferably from 0.01 μm to 3.0 μm, more preferably from 0.03 μm to 2.0 μm, and still more preferably from 0.10 μm to 1.0 μm. Good resolution and stability over time can be obtained within this range.

[0851] Regarding the average primary particle diameter of the above-mentioned particles in the present invention, it is measured by the light scattering method, or an electron micrograph of the particles is taken, and the particle diameters of a total of 5,000 particles are measured on the photograph, and the average value is calculated. In addition, regarding non-spherical particles, the particle diameter value of a spherical particle having the same particle area as the particle area on the photograph is used as the particle diameter.

[0852] Moreover, regarding the average particle diameter in the present invention, unless otherwise specified, it is the volume average particle diameter.

[0853] The above-mentioned image recording layer may contain one kind of particles, particularly polymer particles, alone, or may contain two or more kinds.

[0854] Moreover, from the viewpoints of on-machine developability and UV printing durability, the content of the particles, particularly polymer particles, in the above-mentioned image recording layer is preferably from 5% by mass to 90% by mass, more preferably from 10% by mass to 90% by mass, still more preferably from 20% by mass to 90% by mass, and particularly preferably from 50% by mass to 90% by mass, based on the total mass of the above-mentioned image recording layer.

[0855] Moreover, from the viewpoints of on-machine developability and UV printing durability, the content of the polymer particles in the above-mentioned image recording layer is preferably from 20% by mass to 100% by mass, more preferably from 35% by mass to 100% by mass, still more preferably from 50% by mass to 100% by mass, and particularly preferably from 80% by mass to 100% by mass, based on the total mass of the components having a molecular weight of 3,000 or more in the above-mentioned image recording layer.

[0856] -Binder polymer-

[0857] The image recording layer may contain a binder polymer.

[0858] The above-mentioned thermoplastic resin particles and the above-mentioned polymer particles do not belong to the above-mentioned other binder polymers. That is, the other binder polymers are polymers that are not in particle form.

[0859] As the other binder polymer, a (meth)acrylic resin, a polyvinyl acetal resin, or a polyurethane resin is preferred.

[0860] Among them, the binder polymer can preferably use a well-known binder polymer used in the image recording layer of the lithographic printing plate original. As an example, the binder polymer used in the on-machine developing type lithographic printing plate original (hereinafter, also referred to as the on-machine developing binder polymer) will be described in detail.

[0861] As the on-machine developing binder polymer, a binder polymer having an alkylene oxide chain is preferred. The binder polymer having an alkylene oxide chain may have a poly(alkylene oxide) moiety in the main chain or in the side chain. And it may be a graft polymer having a poly(alkylene oxide) in the side chain, or a block copolymer of a block composed of repeating units containing poly(alkylene oxide) and a block composed of repeating units not containing (alkylene oxide).

[0862] In the case of having a poly(alkylene oxide) moiety in the main chain, a polyurethane resin is preferred. As the polymer when having a poly(alkylene oxide) moiety in the side chain, examples include (meth)acrylic resin, polyvinyl acetal resin, polyurethane resin, polyurea resin, polyimide resin, polyamide resin, epoxy resin, polystyrene resin, novolak type phenol resin, polyester resin, synthetic rubber, natural rubber, and (meth)acrylic resin is particularly preferred.

[0863] And, as another preferred example of the binder polymer, a high molecular compound (hereinafter, also referred to as a star-shaped high molecular compound) having a polyfunctional thiol of 6 to 10 functional groups as the core part and having a polymer chain bonded to the core part through a thioether bond, and the polymer chain having a polymerizable group can be cited. As the star-shaped high molecular compound, for example, a compound described in JP-A-2012-148555 can be preferably used.

[0864] Regarding the star-shaped high molecular compound, a compound having a polymerizable group such as an ethylenically unsaturated bond described in JP-A-2008-195018 in the main chain or side chain, preferably in the side chain, for improving the film strength of the image part can be cited. Crosslinking is formed between polymer molecules through the polymerizable group, and curing is promoted.

[0865] As the polymerizable group, ethylenically unsaturated groups such as (meth)acrylic group, vinyl group, allyl group, vinylphenyl (styryl) group, epoxy group, etc. are preferred, and from the viewpoint of polymerization reactivity, (meth)acrylic group, vinyl group, vinylphenyl (styryl) group are more preferred, and (meth)acrylic group is particularly preferred. These groups can be introduced into the polymer through polymer reactions and copolymerization. For example, the reaction of a polymer having a carboxyl group in the side chain with glycidyl methacrylate, or the reaction of a polymer having an epoxy group with a carboxylic acid containing an ethylenically unsaturated group such as methacrylic acid can be utilized. These groups can be used simultaneously.

[0866] Regarding the molecular weight of the binder polymer, as a polystyrene conversion value based on the GPC method, the weight average molecular weight (Mw) is preferably 2,000 or more, more preferably 5,000 or more, and further preferably 10,000 to 300,000.

[0867] As needed, hydrophilic polymers such as polyacrylic acid and polyvinyl alcohol described in JP-A-2008-195018 can be used simultaneously. Further, a lipophilic polymer and a hydrophilic polymer can be used simultaneously.

[0868] Further, from the viewpoints of UV printing durability and on-machine developability, the above image recording layer preferably contains a polymer having a structural unit formed from an aromatic vinyl compound, more preferably contains a polymer having a structural unit formed from an aromatic vinyl compound, and contains an infrared absorber that decomposes upon infrared exposure.

[0869] Regarding the binder polymer used in the present invention, for example, from the viewpoint of suppressing the decrease in on-machine developability over time, the glass transition temperature (Tg) is preferably 50°C or higher, more preferably 70°C or higher, further preferably 80°C or higher, and particularly preferably 90°C or higher.

[0870] Further, as the upper limit of the glass transition temperature of the binder polymer, from the viewpoint of easily allowing water to penetrate into the image recording layer, it is preferably 200°C, more preferably 120°C or lower.

[0871] As the binder polymer having the above glass transition temperature, polyvinyl acetal is preferred from the viewpoint of further suppressing the decrease in on-machine developability over time.

[0872] Polyvinyl acetal is a resin obtained by acetalizing the hydroxyl groups of polyvinyl alcohol with an aldehyde.

[0873] In particular, polyvinyl butyral obtained by acetalizing the hydroxyl groups of polyvinyl alcohol with butyraldehyde (i.e., butyralization) is preferred.

[0874] Polyvinyl acetal preferably contains a structural unit represented by the following (a) by acetalizing the hydroxyl groups of polyvinyl alcohol with an aldehyde.

[0875] [Chemical formula 68]

[0876]

[0877] Here, as R, it represents the residue of the aldehyde used for acetalization.

[0878] As R, in addition to a hydrogen atom, an alkyl group, etc., an ethylenically unsaturated group described later can also be mentioned.

[0879] The content of the structural unit represented by the above (a) (also referred to as the amount of ethylene groups in the main chain contained in the structural unit represented by the above (a). Further, it is also referred to as the degree of acetalization.), relative to all the structural units of polyvinyl acetal (the total amount of ethylene groups in the main chain), is preferably 50 mol% to 90 mol%, more preferably 55 mol% to 85 mol%, and still more preferably 55 mol% to 80 mol%.

[0880] In addition, the degree of acetalization is a value expressed as a percentage of the mole fraction obtained by dividing the amount of ethylene groups to which the acetal group is bonded (the amount of ethylene groups in the main chain contained in the structural unit represented by the above (a)) by the total amount of ethylene groups in the main chain.

[0881] Moreover, it is the same for the content of each structural unit of polyvinyl acetal described later.

[0882] From the viewpoint of improving printing durability, polyvinyl acetal preferably has an ethylenically unsaturated group.

[0883] Here, the ethylenically unsaturated group possessed by polyvinyl acetal is not particularly limited, and from the viewpoints of reactivity, on-machine developability, and printing durability, it is preferably at least one group selected from the group consisting of vinylphenyl (styryl), vinyl ester group, vinyl ether group, allyl group, (meth)acryloyloxy group, and (meth)acrylamide group, and more preferably vinyl group, allyl group, (meth)acryloyloxy group, etc.

[0884] From the viewpoint of improving printing durability, polyvinyl acetal preferably contains a structural unit having an ethylenically unsaturated group.

[0885] As the structural unit having an ethylenically unsaturated group, it may be a structural unit having the above acetal ring, or may be a structural unit other than the structural unit having an acetal ring.

[0886] Among them, from the viewpoint of increasing the crosslinking density during exposure, polyvinyl acetal is preferably a compound in which an ethylenically unsaturated group is introduced into the acetal ring. That is, in the structural unit represented by the above (a), it is preferred that R has an ethylenically unsaturated group.

[0887] When the structural unit having an ethylenically unsaturated group is a structural unit other than the structural unit having an acetal ring, for example, it may be a structural unit having an acrylate group, and specifically, it may be a structural unit represented by the following (d).

[0888] [Chemical formula 69]

[0889]

[0890] When the structural unit having an ethylenically unsaturated group is a structural unit other than the structural unit having an acetal ring, as the content of this structural unit (also referred to as the amount of acrylate group), relative to all the structural units of polyvinyl acetal, it is preferably 1 mol% to 15 mol%, more preferably 1 mol% to 10 mol%.

[0891] As the polyvinyl acetal, from the viewpoint of on-machine developability and the like, it is preferably to contain a structural unit having a hydroxyl group. That is, the above polyvinyl acetal preferably contains a structural unit derived from vinyl alcohol.

[0892] As the structural unit having a hydroxyl group, a structural unit represented by the following (b) can be cited.

[0893] [Chemical formula 70]

[0894]

[0895] As the content of the structural unit represented by the above (b) (also referred to as the amount of hydroxyl group), from the viewpoint of on-machine developability, relative to all the structural units of polyvinyl acetal, it is preferably 5 mol% to 50 mol%, more preferably 10 mol% to 40 mol%, and further preferably 20 mol% to 40 mol%.

[0896] As the above polyvinyl acetal, other structural units can also be contained.

[0897] As other structural units, for example, a structural unit having an acetyl group can be cited. Specifically, a structural unit represented by the following (c) can be cited.

[0898] [Chemical formula 71]

[0899]

[0900] As the content of the structural unit represented by the above (c) (also referred to as the amount of acetyl group), relative to all the structural units of polyvinyl acetal, it is preferably 0.5 mol% to 10 mol%, more preferably 0.5 mol% to 8 mol%, and further preferably 1 mol% to 3 mol%.

[0901] Here, the above acetalization degree, amount of acrylate group, amount of hydroxyl group, and amount of acetyl group can be obtained in the following manner.

[0902] That is, by 1 1H NMR measurement, the mol content is calculated based on the proton peak area ratio of the methyl or methylene site of the acetal, the methyl site of the acrylate group, the hydroxyl group, and the methyl site of the acetyl group.

[0903] The weight-average molecular weight of the above polyvinyl acetal is preferably from 18,000 to 150,000.

[0904] The solubility parameter (also referred to as the SP value) of the above polyvinyl acetal is preferably 17.5 MPa 1 / 2 to 20.0 MPa 1 / 2 and more preferably 18.0 MPa 1 / 2 to 19.5 MPa 1 / 2 .

[0905] Herein, the "solubility parameter (unit: (MPa) 1 / 2 )" in the present invention uses the Hansen solubility parameter.

[0906] Regarding the Hansen solubility parameter, the solubility parameter introduced by Hildebrand is divided into three components: a dispersion term δd, a polar term δp, and a hydrogen bond term δh, and is shown in a three-dimensional space. However, in the present invention, δ (unit: (MPa) 1 / 2 ) represents the solubility parameter (hereinafter, also referred to as the SP value), and the value calculated using the following formula is used.

[0907] δ (MPa) 1 / 2 = (δd 2 + δp 2 + δh 2 ) 1 / 2

[0908] In addition, a large number of the dispersion term δd, the polar term δp, and the hydrogen bond term δh have been obtained by Hansen or his research successors, etc., and are detailed in Polymer Handbook (fourth edition), VII-698 to 711. And regarding the detailed content of the Hansen solubility parameter value, it is described in the literature "Hansen Solubility Parameters; A Users Handbook" edited by Charles M. Hansen (CRC Press, 2007).

[0909] In the present invention, regarding the Hansen solubility parameter in the partial structure of the compound, it is also possible to use the value deduced from its chemical structure by using the computer software "Hansen Solubility Parameters in Practice (HSPiP ver.4.1.07)".

[0910] Further, in the present invention, in the case where the compound is a polymer such as an addition polymerization type or a polycondensation type, it is represented by the total amount obtained by multiplying the SP value of each monomer unit by the mole fraction, and in the case where the compound is a low molecular compound having no monomer unit, it is the SP value of the compound as a whole.

[0911] In addition, in the present invention, regarding the SP value of a polymer, it can be calculated by the Hoy method described in the Polymer Handbook (fourth edition) according to the molecular structure of the polymer.

[0912] Specific examples [P-1 to P-3] of the above-mentioned polyvinyl acetal are shown below, but the polyvinyl acetal used in the present invention is not limited to these.

[0913] In the following structure, “l” is 50 mol% to 90 mol%, “m” is 0.5 mol% to 10 mol%, “n” is 5 mol% to 50 mol%, and “o” is 1 mol% to 15 mol%.

[0914] [Chemical formula 72]

[0915]

[0916] As the above-mentioned polyvinyl acetal, commercially available products can be used.

[0917] Examples of commercially available products of polyvinyl acetal include the S-LEC series of SEKISUI CHEMICAL CO., LTD. (specifically, S-LEC BX-L, BX-1, BX-5, BL-7Z, BM-1, BM-5, BH-6, BH-3, etc.).

[0918] The image recording layer in the present invention preferably contains a resin having a fluorine atom, and more preferably contains a copolymer containing a fluorinated aliphatic group.

[0919] By using a resin having a fluorine atom, particularly a copolymer containing a fluorinated aliphatic group, it is possible to suppress surface quality abnormalities caused by foaming during the formation of the image recording layer, improve the coating surface state, and moreover, improve the ink inkability of the formed image recording layer.

[0920] In addition, the gray level of the image recording layer containing a copolymer containing a fluorinated aliphatic group becomes higher. For example, it has high sensitivity to a laser beam, and a lithographic printing plate with good fogginess caused by scattered light, reflected light, etc. and excellent printing durability can be obtained.

[0921] The above copolymer containing a fluoroaliphatic group preferably has a structural unit formed from a compound represented by any one of the following formula (F1) and the following formula (F2).

[0922] [Chemical formula 73]

[0923]

[0924] In formula (F1) and (F2), R F1 each independently represents a hydrogen atom or a methyl group, X each independently represents an oxygen atom, a sulfur atom or -N(R F2 ), m represents an integer of 1 to 6, n represents an integer of 1 to 10, l represents an integer of 0 to 10, and R F2 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

[0925] As the alkyl group having 1 to 4 carbon atoms represented by R F2 in formula (F1) and (F2), methyl, ethyl, n-propyl or n-butyl is preferred, and a hydrogen atom or a methyl group is more preferred.

[0926] X in formula (F1) and (F2) is preferably an oxygen atom.

[0927] m in formula (F1) is preferably 1 or 2, and more preferably 2.

[0928] n in formula (F1) is preferably 2, 4, 6, 8, or 10, and more preferably 4 or 6.

[0929] l in formula (F1) is preferably 0.

[0930] Specific examples of the monomer having a fluorine atom used in the resin having a fluorine atom are shown below, but are not limited thereto.

[0931] [Chemical formula 74]

[0932]

[0933] [Chemical formula 75]

[0934]

[0935] [Chemical formula 76]

[0936]

[0937] [Chemical formula 77]

[0938]

[0939] [Chemical formula 78]

[0940]

[0941] [Chemical Formula 79]

[0942]

[0943] [Chemical Formula 80]

[0944]

[0945] [Chemical Formula 81]

[0946]

[0947]

[0948]

[0949] The above copolymer containing a fluoroaliphatic group preferably has, in addition to the structural unit formed from the compound represented by any one of the above formulas (F1) and (F2), a structural unit formed from at least one compound selected from poly(oxyalkylene) acrylate and poly(oxyalkylene) methacrylate).

[0950] In the above poly(oxyalkylene) acrylate and poly(oxyalkylene) methacrylate, the polyoxyalkylene group can be represented by -(OR F3 ) x -, R F3 represents an alkyl group, and x represents an integer of 2 or more. As R F3 , a linear or branched alkylene group having 2 to 4 carbon atoms is preferred. As the linear or branched alkylene group having 2 to 4 carbon atoms, -CH2CH2-, -CH2CH2CH2-, -CH(CH3)CH2-, or -CH(CH3)CH(CH3)- is preferred. x is preferably an integer of 2 to 100.

[0951] In the above polyoxyalkylene group, the x "OR F3 " can be the same or different from each other. That is, the above polyoxyalkylene group can be a group in which two or more "OR F3 " are bonded regularly or irregularly. For example, the above polyoxyalkylene group can be a group in which a linear or branched oxypropylene unit and an oxyethylene unit are bonded regularly or irregularly. More specifically, the above polyoxyalkylene group can be a group in which a block of a linear or branched oxypropylene unit and a block of an oxyethylene unit are bonded.

[0952] In addition, one or more linking groups (for example, -CONH-Ph-NHCO-, -S-, etc., where Ph represents a phenylene group) can be included in the polyoxyalkylene group.

[0953] The molecular weight of the above polyoxyalkylene group is preferably from 250 to 3,000.

[0954] As the above poly(oxyalkylene) acrylate and poly(oxyalkylene) methacrylate, commercially available products can be used, or synthetic products can also be used.

[0955] The above poly(oxyalkylene) acrylate and poly(oxyalkylene) methacrylate can be synthesized, for example, by reacting a hydroxy poly(oxyalkylene) compound with acrylic acid, methacrylic acid, acryloyl chloride, methacryloyl chloride, acrylic anhydride, etc. by a known method.

[0956] As the above hydroxy poly(oxyalkylene) compound, commercially available products can be used. For example, Adeka (registered trademark) Pluronic manufactured by ADEKA CORPORATION, Adeka Polyether manufactured by ADEKA CORPORATION, Carbowax (registered trademark) manufactured by Union Carbide Corporation, Triton manufactured by The Dow Chemical Company, PEG manufactured by DKS Co., Ltd., etc. can be cited.

[0957] In addition, as the poly(oxyalkylene) acrylate and poly(oxyalkylene) methacrylate, poly(oxyalkylene) diacrylate synthesized by a known method can be used.

[0958] In the image recording layer used in the present invention, one binder polymer can be used alone, or two or more can be used simultaneously.

[0959] The binder polymer can be contained in the image recording layer in an arbitrary amount, but relative to the total mass of the image recording layer, the content of the binder polymer is preferably from 1% by mass to 90% by mass, more preferably from 5% by mass to 80% by mass.

[0960] Moreover, when the image recording layer in the present invention contains other binder polymers, the content of the other binder polymers relative to the total mass of the above thermoplastic resin particles and other binder polymers is preferably more than 0% by mass and 99% by mass or less, more preferably from 20% by mass to 95% by mass, and further preferably from 40% by mass to 90% by mass.

[0961] 〔Chain transfer agent〕

[0962] The image recording layer used in the present invention may contain a chain transfer agent. The chain transfer agent helps to improve the UV printing durability in the lithographic printing plate.

[0963] As the chain transfer agent, a thiol compound is preferred. From the viewpoint of boiling point (low volatility), a thiol compound having 7 or more carbon atoms is more preferred, and a compound having a mercapto group on an aromatic ring (aromatic thiol compound) is further preferred. The above thiol compound is preferably a monofunctional thiol compound.

[0964] Specific examples of the chain transfer agent include the following compounds.

[0965] [Chemical formula 84]

[0966]

[0967] [Chemical formula 85]

[0968]

[0969] [Chemical formula 86]

[0970]

[0971] [Chemical formula 87]

[0972]

[0973] Only one kind of chain transfer agent may be added, or two or more kinds may be used simultaneously.

[0974] 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 further preferably 0.1% by mass to 30% by mass based on the total mass of the image recording layer.

[0975] [Sensitizer]

[0976] The image recording layer preferably further contains a sensitizer to improve the ink adhesion.

[0977] The SP value of the sensitizer is preferably less than 18.0, more preferably less than 14 to 18, further preferably 15 to 17, and particularly preferably 16 to 16.9.

[0978] Moreover, the sensitizer may be a compound having a molecular weight (weight average molecular weight when having a molecular weight distribution) of 2,000 or more, or a compound having a molecular weight less than 2,000.

[0979] The SP value (solubility parameter, unit: (MPa) 1 / 2 ) in the present invention uses the Hansen solubility parameter.

[0980] Regarding the Hansen solubility parameter, the solubility parameter introduced by Hildebrand is divided into three components: a dispersion term δd, a polar term δp, and a hydrogen bond term δh, and is shown in three-dimensional space. However, in the present invention, the SP value is represented by δ (unit: (MPa) 1 / 2 ) and the value calculated using the following formula is used.

[0981] δ (MPa) 1 / 2 =(δd 2 +δp 2 +δh 2 ) 1 / 2

[0982] In addition, a large number of such dispersion terms δd, polar terms δp, and hydrogen bond terms δh have been obtained by Hansen or his research successors, etc., and are detailed in Polymer Handbook (fourth edition), VII-698 to 711.

[0983] Moreover, in the present invention, regarding the SP value of a polymer, it is calculated by the Hoy method described in Polymer Handbook fourth edition according to the molecular structure of the polymer.

[0984] Examples of the above-mentioned sensitizer include onium salt compounds, nitrogen-containing low-molecular compounds, ammonium compounds such as polymers containing an ammonium group, etc.

[0985] In particular, when the outer coating contains an inorganic layered compound, these compounds act as surface covering agents for the inorganic layered compound and can suppress the decrease in ink receptivity during printing due to the inorganic layered compound.

[0986] And, from the viewpoint of ink receptivity, the sensitizer is preferably an onium salt compound.

[0987] Examples of the onium salt compound include phosphonium compounds, ammonium compounds, sulfonium compounds, etc. As the onium salt compound, from the above viewpoint, at least one selected from the group consisting of phosphonium compounds and ammonium compounds is preferably selected.

[0988] Moreover, the onium salt compound in the development accelerator or electron-accepting polymerization initiator described later is a compound with an SP value exceeding 18 and is not included in the sensitizer.

[0989] As the phosphonium compound, the phosphonium compounds described in JP-A-2006-297907 and JP-A-2007-50660 can be cited. As specific examples, 1,4-bis(triphenylphosphine)butane bis(hexafluorophosphate), 1,7-bis(triphenylphosphine)heptane sulfate, 1,9-bis(triphenylphosphine)nonane naphthalene-2,7-disulfonate, etc. can be cited.

[0990] As the ammonium compound, a nitrogen-containing low molecular weight compound, a polymer containing an ammonium group, etc. can be preferably selected.

[0991] As the nitrogen-containing low molecular weight compound, amine salts and quaternary ammonium salts can be cited. Further, imidazolinium salts, benzimidazolinium salts, pyridinium salts, quinolinium salts, etc. can also be cited.

[0992] Among them, quaternary ammonium salts and pyridinium salts are preferred.

[0993] As specific examples, tetramethylammonium hexafluorophosphate, tetrabutylammonium hexafluorophosphate, dodecyltrimethylammonium p-toluenesulfonate, benzyltriethylammonium hexafluorophosphate, benzyl dimethyl octylammonium hexafluorophosphate, benzyl dimethyl dodecylammonium hexafluorophosphate, the compounds described in paragraphs 0021 to 0037 of JP-A-2008-284858, the compounds described in paragraphs 0030 to 0057 of JP-A-2009-90645, etc. can be cited.

[0994] As the polymer containing an ammonium group, it is sufficient that it has an ammonium group in its structure, and a polymer having 5 mol% to 80 mol% of a (meth)acrylate having an ammonium group as a copolymer component in the side chain is preferred. As specific examples, the polymers described in paragraphs 0089 to 0105 of JP-A-2009-208458 can be cited.

[0995] Regarding the polymer containing an ammonium group, the value of the reduced viscosity (unit: ml / g) determined by the measurement method described in JP-A-2009-208458 is preferably in the range of 5 to 120, more preferably in the range of 10 to 110, and particularly preferably in the range of 15 to 100. When converting the above reduced viscosity to the weight average molecular weight (Mw), it is preferably 10,000 to 150,000, more preferably 17,000 to 140,000, and particularly preferably 20,000 to 130,000.

[0996] Hereinafter, specific examples of the polymer containing an ammonium group are shown.

[0997] (1) 2-(Trimethylammonio)ethyl methacrylate p-toluenesulfonate / 3,6-dioxaoctyl methacrylate copolymer (molar ratio 10 / 90, Mw 45,000)

[0998] (2)2-(Trimethylammonio)ethyl methacrylate = hexafluorophosphate / 3,6-dioxaoctyl methacrylate copolymer (molar ratio 20 / 80, Mw 60,000)

[0999] (3)2-(Ethyl-dimethylammonio)ethyl methacrylate p-toluenesulfonate / hexyl methacrylate copolymer (molar ratio 30 / 70, Mw 45,000)

[1000] (4)2-(Trimethylammonio)ethyl methacrylate = hexafluorophosphate / 2-ethylhexyl methacrylate copolymer (molar ratio 20 / 80, Mw 60,000)

[1001] (5)2-(Trimethylammonio)ethyl methacrylate = methyl sulfate / hexyl methacrylate copolymer (molar ratio 40 / 60, Mw 70,000)

[1002] (6)2-(Butyl-dimethylammonio)ethyl methacrylate = hexafluorophosphate / 3,6-dioxaoctyl methacrylate copolymer (molar ratio 25 / 75, Mw 65,000)

[1003] (7)2-(Butyl-dimethylammonio)ethyl acrylate = hexafluorophosphate / 3,6-dioxaoctyl methacrylate copolymer (molar ratio 20 / 80, Mw 65,000)

[1004] (8)2-(Butyl-dimethylammonio)ethyl methacrylate = 13-ethyl-5,8,11-trioxa-1-heptadecanesulfonate / 3,6-dioxaoctyl methacrylate copolymer (molar ratio 20 / 80, Mw 75,000)

[1005] Relative to the total mass of the image recording layer, the content of the sensitizer is preferably 1% by mass to 40.0% by mass, more preferably 2% by mass to 25.0% by mass, and still more preferably 3% by mass to 20.0% by mass.

[1006] The image recording layer may contain a single sensitizer alone, or may use two or more kinds simultaneously.

[1007] One of the preferred embodiments of the image recording layer used in the present invention is a mode in which two or more compounds are used as the sensitizer.

[1008] Specifically, in the image recording layer used in the present invention, from the viewpoint of balancing on-machine developability and inkability, as the sensitizer, it is preferable to use a phosphonium compound, a low-molecular nitrogen-containing compound, and an ammonium group-containing polymer simultaneously, and it is more preferable to use a phosphonium compound, quaternary ammonium salts, and an ammonium group-containing polymer simultaneously.

[1009] 〔Development accelerator〕

[1010] The image recording layer used in the present invention preferably further contains a development accelerator.

[1011] Regarding the development accelerator, the value of the polar term of the SP value is preferably 6.0 to 26.0, more preferably 6.2 to 24.0, still more preferably 6.3 to 23.5, and particularly preferably 6.4 to 22.0.

[1012] In the present invention, the value of the polar term of the SP value (solubility parameter, unit: (cal / cm 3 ) 1 / 2 ) uses the value of the polar term δp in the Hansen solubility parameter. Regarding the Hansen solubility parameter, the solubility parameter introduced by Hildebrand is divided into three components: a dispersion term δd, a polar term δp, and a hydrogen bond term δh, and is shown in a three-dimensional space. However, in the present invention, the above-mentioned polar term δp is used.

[1013] δp [cal / cm 3 is the dipole force term of the Hansen solubility parameter, V [cal / cm 3 is the molar volume, and μ [D] is the dipole moment. As δp, the following formula simplified by Hansen and Beerbower is usually used.

[1014] [Equation 1]

[1015]

[1016] As the development accelerator, a hydrophilic polymer compound or a hydrophilic low-molecular compound is preferred.

[1017] In the present invention, hydrophilicity means that the value of the polar term of the SP value is 6.0 to 26.0. A hydrophilic polymer compound means a compound having a molecular weight (weight-average molecular weight in the case of having a molecular weight distribution) of 3,000 or more, and a hydrophilic low-molecular compound means a compound having a molecular weight (weight-average molecular weight in the case of having a molecular weight distribution) of less than 3,000.

[1018] As the hydrophilic polymer compound, a cellulose compound etc. can be mentioned, and a cellulose compound is preferred.

[1019] As the cellulose compound, cellulose or a compound in which at least a part of cellulose is modified (modified cellulose compound) can be mentioned, and a modified cellulose compound is preferred.

[1020] As the modified cellulose compound, a compound obtained by substituting at least a part of the hydroxyl groups of cellulose with at least one group selected from the group consisting of an alkyl group and a hydroxyalkyl group is preferably selected.

[1021] The degree of substitution of the compound obtained by substituting at least a part of the hydroxyl groups of the above cellulose with at least one group selected from the group consisting of an alkyl group and a hydroxyalkyl group is preferably from 0.1 to 6.0, more preferably from 1 to 4.

[1022] As the modified cellulose compound, an alkyl cellulose compound or a hydroxyalkyl cellulose compound is preferred, and a hydroxyalkyl cellulose compound is more preferred.

[1023] As the alkyl cellulose compound, methyl cellulose is preferably selected.

[1024] As the hydroxyalkyl cellulose compound, hydroxyalkyl cellulose is preferably selected.

[1025] The molecular weight of the hydrophilic polymer compound (weight-average molecular weight in the case of having a molecular weight distribution) is preferably from 3,000 to 5,000,000, more preferably from 5,000 to 200,000.

[1026] Examples of the hydrophilic low molecular weight compound include a diol compound, a polyol compound, an organic amine compound, an organic sulfonic acid compound, an organic aminosulfonyl compound, an organic sulfuric acid compound, an organic phosphonic acid compound, an organic carboxylic acid compound, a betaine compound, etc., and a polyol compound, an organic sulfonic acid compound or a betaine compound is preferred.

[1027] Examples of the diol compound include diols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, and ether or ester derivatives of these compounds.

[1028] Examples of the polyol compound include glycerin, pentaerythritol, tris(2-hydroxyethyl)isocyanurate, etc.

[1029] Examples of the organic amine compound include triethanolamine, diethanolamine, monoethanolamine, etc. and their salts.

[1030] Examples of the organic sulfonic acid compound include alkyl sulfonic acid, toluene sulfonic acid, benzene sulfonic acid, etc. and their salts, and alkyl sulfonic acid having 1 to 10 carbon atoms in the alkyl group is preferably selected.

[1031] Examples of the organic aminosulfonyl compound include alkylaminosulfonic acid, etc. and their salts.

[1032] Examples of the organic sulfuric acid compound include alkyl sulfuric acid, alkyl ether sulfuric acid, etc. and their salts.

[1033] Examples of the organic phosphonic acid compound include phenylphosphonic acid, etc. and their salts.

[1034] Examples of the organic carboxylic acid compound include tartaric acid, oxalic acid, citric acid, malic acid, lactic acid, gluconic acid, etc. and their salts.

[1035] As betaine compounds, phosphobetaine compounds, sulfobetaine compounds, carboxybetaine compounds and the like can be mentioned, and trimethylglycine is preferably selected.

[1036] The molecular weight of the hydrophilic low-molecular compound (the weight-average molecular weight in the case of having a molecular weight distribution) is preferably 100 or more and less than 3,000, and more preferably 300 to 2,500.

[1037] The development accelerator is preferably a compound having a cyclic structure.

[1038] As the cyclic structure, there is no particular limitation, but a glucose ring, an isocyanuric ring, an aromatic ring which may have a heteroatom, an aliphatic ring which may have a heteroatom, etc. in which at least a part of the hydroxyl group can be substituted are preferably selected, and a glucose ring or an isocyanuric ring is preferably selected.

[1039] As the compound having a glucose ring, the above-mentioned cellulose compound can be mentioned.

[1040] As the compound having an isocyanuric ring, the above-mentioned tris(2-hydroxyethyl) isocyanurate and the like can be mentioned.

[1041] As the compound having an aromatic ring, the above-mentioned toluenesulfonic acid, benzenesulfonic acid and the like can be mentioned.

[1042] As the compound having an aliphatic ring, the above-mentioned alkyl sulfate in which the alkyl group has a ring structure and the like can be mentioned.

[1043] Furthermore, the compound having a cyclic structure preferably has a hydroxyl group.

[1044] As the compound having a hydroxyl group and a cyclic structure, the above-mentioned cellulose compound and the above-mentioned tris(2-hydroxyethyl) isocyanurate are preferably selected.

[1045] Furthermore, as the development accelerator, an onium salt compound is preferably used.

[1046] As the onium salt compound, ammonium compounds, sulfonium compounds and the like can be mentioned, and ammonium compounds are preferably used.

[1047] As the onium salt compound, that is, the development accelerator, trimethylglycine and the like can be mentioned.

[1048] Furthermore, the onium salt compound in the above-mentioned electron-accepting type polymerization initiator is a compound in which the value of the polar term of the SP value is not 6.0 to 26.0, and is not included in the development accelerator.

[1049] The image recording layer may contain one kind of development accelerator alone, or two or more kinds may be used simultaneously.

[1050] One of the preferred modes of the image recording layer used in the present invention is a mode in which two or more kinds of compounds are used as the development accelerator.

[1051] Specifically, from the viewpoints of on-machine developability and ink receptivity, the image recording layer used in the present invention preferably contains the above-mentioned polyol compound and the above-mentioned betaine compound, the above-mentioned betaine compound and the above-mentioned organic sulfonic acid compound, or the above-mentioned polyol compound and the above-mentioned organic sulfonic acid compound as a development accelerator.

[1052] The content of the development accelerator relative to the total mass of the image recording layer is preferably 0.1% by mass or more and 20% by mass or less, more preferably 0.5% by mass or more and 15% by mass or less, and still more preferably 1% by mass or more and 10% by mass or less.

[1053] 〔Other components〕

[1054] The image recording layer can contain a surfactant, a polymerization inhibitor, a higher fatty acid derivative, a plasticizer, inorganic particles, an inorganic layered compound, etc. as other components. Specifically, the description in paragraphs 0114 to 0159 of Japanese Patent Application Laid-Open No. 2008-284817 can be referred to.

[1055] 〔Formation of the image recording layer〕

[1056] The image recording layer in the lithographic printing plate precursor according to the present disclosure can be formed, for example, by the following method: as described in paragraphs 0142 to 0143 of Japanese Patent Application Laid-Open No. 2008-195018, the above-mentioned respective necessary components are dispersed or dissolved in a known solvent to prepare a coating solution, and the coating solution is coated on a support by a known method such as bar coating and dried. The coating amount (solid content) of the image recording layer after coating and drying varies depending on the use, but is preferably 0.3 g / m 2 ~3.0 g / m 2 . Within this range, good sensitivity and good film properties of the image recording layer can be obtained.

[1057] As the solvent, known solvents can be used. Specifically, for example, water, acetone, methyl ethyl ketone (2-butanone), cyclohexane, ethyl acetate, dichloroethane, 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 monoethyl 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, ethyl lactate, etc. can be cited. The solvent can be used alone or two or more kinds can be used simultaneously. The concentration of the solid component in the coating liquid is preferably 1% by mass to 50% by mass.

[1058] The coating amount (solid component) of the image recording layer after coating and drying varies depending on the use, but from the viewpoint of obtaining good sensitivity and good film properties of the image recording layer, it is preferably 0.3 g / m 2 ~3.0 g / m 2 .

[1059] Moreover, the film thickness of the image recording layer in the lithographic printing plate original of the present invention is preferably 0.1 μm to 3.0 μm, more preferably 0.3 μm to 2.0 μm.

[1060] In the present invention, the film thickness of each layer in the lithographic printing plate original is confirmed by preparing a section cut along a direction perpendicular to the surface of the lithographic printing plate original and observing the cross section of the section with a scanning microscope (SEM).

[1061] <Support>

[1062] The lithographic printing plate original of the present invention has a support.

[1063] As the support, a support having a hydrophilic surface (also referred to as a "hydrophilic support") is preferred. As the hydrophilic surface, the contact angle with water is preferably less than 10°, more preferably less than 5°.

[1064] Regarding the water contact angle in the present invention, it is measured as the contact angle (after 0.2 seconds) of a water droplet on the surface under the condition of 25 °C by DM-501 manufactured by Kyowa Interface Science Co., Ltd.

[1065] The support for the original lithographic printing plate according to the present disclosure can be appropriately selected from known supports for original lithographic printing plates and used. As the support, an aluminum plate obtained by roughening treatment and anodizing treatment by a known method is preferred.

[1066] Hereinafter, the support used in the original lithographic printing plate according to the present invention will be described with reference to the accompanying drawings. However, in the description of the drawings, symbols may sometimes be omitted.

[1067] The thickness of the anodic oxide film is preferably 200 nm to 2,000 nm.

[1068] Figure 2A FIG. shows a schematic cross-sectional view of an embodiment of an aluminum support having an anodic oxide film. In Figure 2A FIG., the aluminum support 12 having an anodic oxide film sequentially has an aluminum plate 18 and an anodic oxide film 20 of aluminum (hereinafter, also simply referred to as "anodic oxide film 20"). The anodic oxide film 20 in the aluminum support 12 is located on Figure 1 the side of the image recording layer 16 of the original lithographic printing plate 10 in FIG. That is, the original lithographic printing plate 10 has an aluminum plate 18, an anodic oxide film 20, an undercoat 14, and an image recording layer 16.

[1069] [Aluminum plate]

[1070] The aluminum plate (aluminum support) contains a metal mainly composed of aluminum with stable dimensions, that is, aluminum or an aluminum alloy. The aluminum plate contains a pure aluminum plate or an alloy plate mainly composed of aluminum and containing a small amount of foreign elements.

[1071] Among the foreign elements contained in the aluminum alloy, there are silicon, iron, manganese, copper, magnesium, chromium, zinc, bismuth, nickel, titanium, etc. The content of the foreign elements in the alloy is 10% by mass or less. As the aluminum plate, a pure aluminum plate is preferred. However, from the perspective of smelting technology, it is difficult to manufacture completely pure aluminum, so a small amount of foreign elements can be contained. The composition of the aluminum plate 18 is not limited, and known and commonly used raw materials (for example, JIS A 1050, JIS A 1100, JIS A 3103, and JIS A 3005) can be appropriately used.

[1072] Preferably, the width of the aluminum plate is about 400 mm to 2,000 mm, and the thickness is about 0.1 mm to 0.6 mm. The width or thickness can be appropriately changed according to the size of the printing press, the size of the printing plate, and the needs of the user.

[1073] The support used in the original lithographic printing plate according to the present invention preferably has micropores on the surface on the image recording layer side, and more preferably has an anodic oxide film on the surface on the image recording layer side and micropores on the surface of the anodic oxide film.

[1074] It is inferred that by simultaneously using the above infrared absorber, the above polymerization initiator, the above polymerizable compound, and the above thermoplastic resin particles in the image recording layer of the original lithographic printing plate, in addition to the heat fusion bonding of the thermoplastic resin particles to each other, the polymerizable compound is polymerized while being mixed with the heat fusion bonded product of the thermoplastic resin particles, thereby forming a stronger film, and having micropores on the surface of the anodic oxide film. Therefore, even within the micropores, the adhesion between the support and the image recording layer is improved by the same polymerization of the polymerizable compound as described above, and thus the UV printing durability is excellent.

[1075] From the viewpoint of UV printing durability, the average diameter of the micropores on the above surface is preferably more than 13 nm and 100 nm or less, more preferably 15 nm to 80 nm, and still more preferably 20 nm to 60 nm.

[1076] In the present invention, the term "micropore" is a commonly used term for indicating pores formed on the surface of the support on the image recording layer side, specifically, a commonly used term for indicating pores in the anodic oxide film, and the size of the pores is not determined.

[1077] The L of the surface on the image recording layer side of the aluminum support (the surface on the image recording layer side of the anodic oxide film) * a * b * The lightness L in the colorimetric system * is preferably 70 to 100. Among them, from the viewpoint of more excellent balance between printing durability and image visual recognition, 75 to 100 is preferred, and 75 to 90 is more preferred.

[1078] Regarding the above lightness L * is measured using a color difference meter Spectro Eye manufactured by X-Rite Inc.

[1079] The following shows an example of a preferred embodiment of the aluminum support used in the present invention (the aluminum support related to this example is also referred to as "support (1)").

[1080] That is, the support (1) has an aluminum plate and an anodic oxide film of aluminum disposed on the above aluminum plate. The above anodic oxide film is located closer to the above image recording layer side than the above aluminum plate. The above anodic oxide film has micropores extending along the depth direction from the surface on the image recording layer side. The average diameter of the above micropores on the surface of the above anodic oxide film exceeds 10 nm and is 100 nm or less. The L of the surface on the image recording layer side of the above anodic oxide film * a * b * The lightness L in the colorimetric system * is 70 to 100.

[1081] It is also preferably selected in the following manner (hereinafter, the support body involved in the above manner will also be referred to as "support body (2)"): In the support body (1), the micropores are composed of a large-diameter pore portion and a small-diameter pore portion. The large-diameter pore portion extends from the surface of the anodic oxide film to a position with a depth of 10 nm to 1,000 nm. The small-diameter pore portion communicates with the bottom of the large-diameter pore portion and extends from the communication position to a position with a depth of 20 nm to 2,000 nm. The average diameter of the large-diameter pore portion on the surface of the anodic oxide film is 15 nm to 150 nm, and the average diameter of the small-diameter pore portion at the communication position is 13 nm or less.

[1082] 〔Anodic oxide film〕

[1083] The support body used in the original lithographic printing plate according to the present invention preferably has an anodic oxide film on the surface on the image recording layer side.

[1084] In Figure 2A , the anodic oxide film 20 refers to an anodized aluminum film that is usually formed on the surface of the aluminum plate 18 by anodic oxidation treatment and has ultra-fine micropores 22 that are substantially perpendicular to the film surface and are uniformly distributed respectively. The micropores 22 extend along the thickness direction (the side of the aluminum plate 18) from the surface of the anodic oxide film.

[1085] The thickness X1 of the anodic oxide film is preferably 200 nm to 2,000 nm, more preferably 500 nm to 1,800 nm, and further preferably 750 nm to 1,500 nm.

[1086] The aluminum support body used in the original lithographic printing plate according to the present invention is preferably any one of the following methods 1 to 3.

[1087] (Method 1)

[1088] The above micropores extend from the surface of the anodic oxide film to a position with a depth exceeding 10 nm. The ratio of the average diameter of the bottom of the micropores to the average diameter of the micropores on the surface of the anodic oxide film is 0.8 times or more and 1.2 times or less.

[1089] (Method 2)

[1090] The above micropores are composed of a large-diameter pore portion and a small-diameter pore portion. The large-diameter pore portion extends from the surface of the anodic oxide film to a position with a depth of 10 nm to 1,000 nm. The small-diameter pore portion communicates with the bottom of the large-diameter pore portion and extends along the depth direction from the communication position to a position with a depth of 20 nm to 2,000 nm. The average diameter of the large-diameter pore portion exceeds 13 nm and is 100 nm or less, and the average diameter of the small-diameter pore portion is 5% to 80% of the average diameter of the large-diameter pore portion.

[1091] (Method 3)

[1092] The average diameter of the micropores on the surface of the anodic oxide film is 10 nm or more and 30 nm or less, and the average value of the maximum diameter inside is 20 nm or more and 300 nm, and the average value of the maximum diameter inside is larger than the average diameter of the micropores on the surface of the anodic oxide film.

[1093] Hereinafter, each method will be described with reference to the drawings.

[1094] 〔Regarding Method 1〕

[1095] Figure 2A It is a schematic cross-sectional view showing an embodiment of the above Method 1.

[1096] In Figure 2A the micropores 22 extend from the surface of the anodic oxide film 20 to a position deeper than 10 nm, and the ratio of the average diameter of the bottom of the micropores to the average diameter of the micropores on the surface of the anodic oxide film is 0.8 times or more and 1.2 times or less.

[1097] The depth X2 of the micropores 22 is preferably more than 10 nm and 50 nm or more, and more preferably 75 nm or more.

[1098] Regarding the depth X2 of the above micropores 22, the cross-section (150,000 times) of the anodic oxide film 20 is observed by FE-SEM, and in the obtained image, the depths of 25 micropores are measured and obtained as the arithmetic mean.

[1099] The average diameter Y1 of the micropores 22 on the surface of the anodic oxide film is preferably more than 13 nm and 100 nm or less, more preferably 15 nm or more and 75 nm or less, and still more preferably 20 nm or more and 50 nm or less.

[1100] The ratio (X2 / Y1) of the average diameter Y1 of the micropores 22 on the surface of the anodic oxide film to the depth X2 is preferably 2 times or more and 10 times or less, more preferably 2.5 times or more and 7 times or less, and still more preferably 3 times or more and 6 times or less.

[1101] And, the average diameter Y2 of the bottom of the micropores 22 is preferably 10 nm or more and 100 nm or less, more preferably 15 nm or more and 75 nm or less, and still more preferably 20 nm or more and 50 nm or less.

[1102] The ratio of the average diameter Y2 of the bottom of the micropores 22 to the average diameter Y1 of the micropores 22 on the surface of the anodic oxide film is preferably 0.8 times or more and 1.2 times or less, more preferably 0.85 times or more and 1.15 times or less, and still more preferably 0.9 times or more and 1.1 times or less.

[1103] The ratio of the average diameter Y2 at the bottom of the micropore 22 to the average diameter Y1 of the micropore 22 on the anodic oxide film surface is the value obtained by the following formula 1A.

[1104] Formula 1A: (Average diameter Y1 of the micropore 22 on the anodic oxide film surface) / (Average diameter Y2 at the bottom of the micropore 22)

[1105] Regarding the average diameter Y1 of the micropores on the anodic oxide film surface, the surface of the anodic oxide film 20 was observed at a magnification of 150,000 times using a field emission scanning electron microscope (FE-SEM) with N = 4 sheets. In the obtained 4 images, the diameters of the micropores existing within a range of 400 nm × 600 nm were measured and obtained as the arithmetic mean.

[1106] When the shape (shape of the opening) of the micropores on the anodic oxide film surface is not circular, the circular equivalent diameter is used.

[1107] Regarding the average diameter Y2 at the bottom of the micropore 22, the surface of the anodic oxide film 20 was observed at a magnification of 150,000 times using a FE-SEM with N = 4 sheets. In the obtained 4 images, the diameters of the bottoms of the micropores 22 existing within a range of 400 nm × 600 nm were measured and obtained as the arithmetic mean. Additionally, when the depth of the micropore 22 is deep, if necessary, the upper part of the anodic oxide film 20 can be cut in a manner parallel to the anodic oxide film (for example, cut by argon), and then the surface of the anodic oxide film 20 is observed using the above-mentioned FE-SEM to obtain the average diameter Y2 at the bottom of the micropore 22.

[1108] In addition, when the shape of the bottom of the micropore is not circular, the circular equivalent diameter is used.

[1109] And when the shape of the bottom is not planar, for example, measure Figure 2B Y2-1 described in as the average diameter of the bottom.

[1110] Figure 2B is an enlarged Figure 2A schematic cross-sectional view of one of the micropores in.

[1111] The shape of the micropores 22 in Method 1 is not particularly limited. For example, a substantially straight tubular shape (substantially cylindrical shape), a conical shape in which the diameter decreases as it goes deeper in the depth direction (thickness direction), an inverted conical shape in which the diameter increases as it goes deeper in the depth direction (thickness direction), a cylindrical shape with a large diameter at the central part, a cylindrical shape with a small diameter at the central part, etc. can be cited, and a substantially straight tubular shape is preferred. The shape of the bottom of the micropore 22 is not particularly limited and can be a curved surface shape (concave shape) or a flat surface shape.

[1112] The ratio (Y1A / Y1) of the diameter Y1A of the central part to the average diameter Y1 of the micropores 22 on the surface of the anodic oxide film is preferably 0.8 times or more and 1.2 times or less.

[1113] Regarding the average diameter Y1A of the central part of the micropores 22, the surface of the anodic oxide film 20 is observed with a FE-SEM at a magnification of 150,000 times with N = 4 sheets. In the obtained 4 images, the diameter of the central part of the micropores 22 existing within a range of 400 nm × 600 nm is measured and obtained as the arithmetic mean. In addition, when the depth of the micropores 22 is deep, if necessary, the upper part of the anodic oxide film 20 is cut in a manner parallel to the anodic oxide film (for example, cut by argon), and then the surface of the anodic oxide film 20 is observed with the above-mentioned FE-SEM to obtain the diameter Y1A of the central part of the bottom of the micropores 22.

[1114] -Other characteristics-

[1115] The density of the micropores 22 on the surface of the anodic oxide film 20 is not particularly limited, but relative to the unit area of the anodic oxide film, it is preferably 200 pores / μm 2 ~2,000 pores / μm 2 and more preferably 200 pores / μm 2 ~1,000 pores / μm 2 .

[1116] Regarding the above density, the surface of the anodic oxide film 20 is observed with a field emission scanning electron microscope (FE-SEM) at a magnification of 150,000 times with N = 4 sheets. In the obtained 4 images, the number of micropores existing within a range of 400 nm × 600 nm is measured and calculated as the arithmetic mean of the measured values.

[1117] In the anodic oxide film 20, the above-mentioned micropores 22 can be distributed over the entire surface of the anodic oxide film or at least a part thereof, but preferably distributed over the entire surface.

[1118] Preferably, the micropores 22 are substantially perpendicular to the surface of the anodic oxide film 20.

[1119] Further, preferably, the micropores 22 are distributed in a nearly uniform state respectively.

[1120] [Regarding Method 2]

[1121] Figure 3A is a schematic cross-sectional view showing an embodiment of the above Method 2

[1122] The micropores 22 in the anodic oxide film 20 are composed of a large-diameter hole portion 24 and a small-diameter hole portion 26. The large-diameter hole portion 24 extends from the surface of the anodic oxide film to a position with a depth (depth A: reference Figure 3A ) of 10 nm to 1,000 nm, and the small-diameter hole portion 26 communicates with the bottom of the large-diameter hole portion 24 and further extends along the depth direction from the communication position.

[1123] Hereinafter, the large-diameter hole portion 24 and the small-diameter hole portion 26 will be described in detail.

[1124] - Large-diameter hole portion -

[1125] It is presumed that a part of the image recording layer in the present invention that contacts the support enters the large-diameter hole portion on the surface of the anodic oxide film, and an anchoring effect is exerted, so that the adhesiveness between the image portion and the support becomes high, and the printing durability of the image portion during printing is improved.

[1126] The average diameter (average opening diameter) of the micropores on the surface of the anodic oxide film of the large-diameter hole portion 24 is preferably 10 nm to 100 nm or less. From the viewpoint of more excellent UV printing durability, the average diameter of the micropores is more preferably more than 13 nm and 100 nm or less, further preferably 15 nm to 60 nm, and particularly preferably 18 nm to 40 nm.

[1127] When the average diameter of the above micropores is greater than 13 nm, it is easy to obtain an offset printing plate with excellent UV printing durability. And if the average diameter of the above micropores is 100 nm or less, it is easy to obtain an offset printing plate with excellent ink removal ability for interrupted printing.

[1128] In this specification, excellent ink removal ability for interrupted printing means that after printing using the offset printing plate, when printing is interrupted (for example, interrupted for several hours, etc.) and printing is restarted, the number of printed sheets required to obtain a printed matter without observed contamination is small.

[1129] Regarding the average diameter of the large-diameter hole portion 24, the surface of the anodic oxide film 20 is observed with a field emission scanning electron microscope (FE-SEM) at a magnification of 150,000 times with N = 4 sheets, and in the 4 obtained images, the diameters (diameter) of the micropores (large-diameter hole portion) existing in the range of 400 nm × 600 nm are measured and calculated as the arithmetic mean.

[1130] In addition, in the case where the shape of the large-diameter hole portion 24 is not circular, the circular equivalent diameter is used.

[1131] The bottom of the large-diameter hole portion 24 is preferably located at a position 10 nm to 1,000 nm from the anodic oxide film surface in terms of depth (hereinafter, sometimes also referred to as "depth A"). That is, the large-diameter hole portion 24 is preferably a hole portion that extends 10 nm or more along the depth direction (thickness direction) from the anodic oxide film surface. Among them, from the viewpoint of more excellent effects of the present invention, the depth A is preferably more than 10 nm and 1,000 nm or less, more preferably 25 nm to 200 nm, and further preferably 70 nm to 100 nm.

[1132] If the above-mentioned depth A is 10 nm or more, it is easier to obtain a lithographic printing plate excellent in small-dot printing durability, development latitude of small dots, and printing durability of a solid image portion. And if the above-mentioned depth A is 1,000 nm or less, it is easy to obtain a lithographic printing plate having particularly excellent ink removal ability during interrupted printing.

[1133] In this specification, "small-dot printing durability" particularly refers to the printing durability of small dots (for example, image portions having a diameter (circular equivalent diameter) of several μm to several tens of μm, etc.).

[1134] Regarding the depth from the above-mentioned anodic oxide film surface, the cross-section (150,000 times) of the anodic oxide film 20 is observed by FE-SEM, and in the obtained image, the depths of 25 large-diameter hole portions are measured and obtained as the arithmetic average.

[1135] The shape of the large-diameter hole portion 24 is not particularly limited. For example, a substantially straight tube shape (substantially cylindrical shape), a conical shape in which the diameter decreases as it goes toward the depth direction (thickness direction), and an inverted conical shape in which the diameter increases as it goes toward the depth direction (thickness direction) can be cited, and a substantially straight tube shape is preferred. In addition, the diameter of the bottom of the large-diameter hole portion usually can have a difference of about 1 nm to 10 nm from the diameter of the opening portion. The shape of the bottom of the large-diameter hole portion 24 is not particularly limited and can be a curved surface shape (concave shape) or a flat surface shape.

[1136] -Small-diameter hole portion-

[1137] As Figure 3A shown, the above-mentioned micropores preferably further have a small-diameter hole portion 26, which is a hole portion that communicates with the bottom of the large-diameter hole portion 24 and further extends along the depth direction (thickness direction) from the communication position.

[1138] One small-diameter hole portion 26 usually communicates with one large-diameter hole portion 24, but two or more small-diameter hole portions 26 can communicate with the bottom of one large-diameter hole portion 24.

[1139] The average diameter at the connection position of the small-diameter hole portion 26 is not particularly limited, but the average diameter of the small-diameter hole portion 26 connected to the bottom of the large-diameter hole portion 24 is smaller than the average diameter of the large-diameter hole portion 24, preferably less than 20 nm, more preferably 15 nm or less, further preferably 13 nm or less, and particularly preferably 10 nm or less. The average diameter is preferably 5 nm or more. When the average diameter is less than 20 nm, it is easy to obtain an offset printing plate with excellent ink removal ability for suspended printing.

[1140] Regarding the average diameter of the small-diameter hole portion 26, the surface of the anodic oxide film 20 was observed with a FE-SEM at a magnification of 150,000 times with N = 4 sheets, and in the 4 obtained images, the diameters of the micropores (small-diameter hole portions) existing within a range of 400 nm × 600 nm were measured and calculated as the arithmetic mean.

[1141] In addition, when the depth of the large-diameter hole portion is deep, if necessary, for example, the upper part (the region having the large-diameter hole portion) of the anodic oxide film 20 can be cut with argon or the like, and then the surface of the anodic oxide film 20 is observed with the above-mentioned FE-SEM, and the average diameter of the small-diameter hole portion is calculated.

[1142] In addition, when the shape of the small-diameter hole portion 26 is not circular, the equivalent circular diameter is used.

[1143] The bottom of the small-diameter hole portion 26 is preferably located at a position further extending 20 nm to 2,000 nm (more preferably greater than 100 nm and less than 1,940 nm) in the depth direction from the connection position with the above-mentioned large-diameter hole portion 24 (corresponding to the above-mentioned depth A). In other words, the depth of the small-diameter hole portion 26 is preferably 20 nm to 2,000 nm (more preferably greater than 100 nm and less than 1,940 nm). Among them, from the viewpoint of more excellent effects of the present invention, the small-diameter hole portion 26 preferably extends from the connection position to a position with a depth of 300 nm to 1,600 nm, and the small-diameter hole portion 26 more preferably extends from the connection position to a position with a depth of 900 nm to 1,300 nm.

[1144] When the depth from the connection position is 20 nm or more, it is easy to obtain an original offset printing plate with excellent scratch resistance. When the depth from the connection position is 2,000 nm or less, the processing time is shortened, and the productivity and economy are likely to be excellent.

[1145] Regarding the depth of the above-mentioned small-diameter hole portion, the cross-section (50,000 times) of the anodic oxide film 20 was observed with a FE-SEM, and in the obtained image, the depths of 25 small-diameter hole portions were measured and calculated as the arithmetic mean.

[1146] The shape of the small-diameter hole portion 26 is not particularly limited. For example, a substantially straight tubular shape (substantially cylindrical shape), a conical shape in which the diameter decreases toward the depth direction, or a dendritic shape that branches toward the depth direction can be cited. A substantially straight tubular shape is preferred. The diameter of the bottom of the small-diameter hole portion 26 usually has a difference of about 1 to 5 nm from the diameter at the connection position. The shape of the bottom of the small-diameter hole portion 26 is not particularly limited and may be a curved surface shape (concave shape) or a flat surface shape.

[1147] In the aluminum support having an anodic oxide film, it is preferred that the average diameter of the small-diameter hole portion at the above connection position is smaller than the average diameter of the large-diameter hole portion on the surface of the anodic oxide film. By making the average diameter of the small-diameter hole portion smaller than the average diameter of the large-diameter hole portion, it is easy to obtain a lithographic printing plate with excellent stain resistance (deinking ability during printing suspension).

[1148] Regarding the average diameter of the large-diameter hole portion and the average diameter of the small-diameter hole portion, the ratio, that is, the average diameter of the large-diameter hole portion / the average diameter of the small-diameter hole portion is preferably 1.1 to 12.5, more preferably 1.5 to 10.

[1149] Furthermore, from the viewpoint of excellent UV printing durability, it is preferred that the average diameter of the small-diameter hole portion is smaller than the average diameter of the large-diameter hole portion on the surface of the anodic oxide film. More preferably, it is 5% to 80% of the average diameter of the large-diameter hole portion, and further preferably 10% to 60%.

[1150] As Figure 3B shown, the micropores can be in a shape where the average diameter of the bottom of the large-diameter hole portion is larger than the average diameter on the surface of the anodic oxide film, and can also be micropores having a small-diameter hole portion communicating with the bottom of the large-diameter hole portion. When the average diameter of the bottom of the large-diameter hole portion is larger than the average diameter on the surface of the anodic oxide film, the average diameter on the surface of the anodic oxide film is preferably 10 nm to 100 nm, more preferably more than 13 nm and 100 nm or less, and the average diameter of the bottom is preferably 20 nm to 300 nm.

[1151] When the shape is such that the average diameter of the bottom of the large-diameter hole portion is larger than the average diameter on the surface of the anodic oxide film, the average diameter of the micropores on the surface of the anodic oxide film is preferably 10 nm to 100 nm. From the viewpoint of stain resistance (deinking ability during printing suspension), it is more preferably more than 13 nm and 30 nm or less. The average diameter of the bottom can be 20 nm to 300 nm, but is preferably 40 nm to 200 nm.

[1152] And, if the thickness of the portion from the surface of the anodic oxide film to a depth of 10 nm to 100 nm is 10 nm to 500 nm, it is preferred, but from the viewpoint of scratch resistance, it is more preferably 50 nm to 300 nm.

[1153] -Other characteristics-

[1154] The density of the micropores 22 on the surface of the anodic oxide film 20 is not particularly limited, but relative to the unit area of the anodic oxide film, it is preferably 200 pores / μm 2 ~2,000 pores / μm 2 , more preferably 200 pores / μm 2 ~1,000 pores / μm 2 .

[1155] Regarding the above density, the surface of the anodic oxide film 20 is observed with a field emission scanning electron microscope (FE-SEM) at a magnification of 150,000 times with N = 4 sheets. In the 4 obtained images, the number of micropores existing in the range of 400 nm × 600 nm is measured, and it is calculated as the arithmetic mean of the measured values.

[1156] In the anodic oxide film 20, the above micropores 22 may be distributed on the entire surface of the anodic oxide film, or may be distributed on at least a part, but are preferably distributed on the entire surface.

[1157] Preferably, the micropores 22 are substantially perpendicular to the surface of the anodic oxide film 20.

[1158] Moreover, preferably, the micropores 22 are distributed in a nearly uniform state respectively.

[1159] 〔Regarding Mode 3; Average diameter of micropores〕

[1160] Figure 4A is a schematic cross-sectional view showing an embodiment of the above Mode 3

[1161] In Figure 4A , the average diameter Y3 of the above micropores 22 on the surface of the anodic oxide film is 10 nm to 30 nm, and the average value Y4 of the maximum diameter inside is 20 nm to 300 nm. The average value Y4 of the maximum diameter inside is larger than the average diameter Y3 of the above micropores on the surface of the anodic oxide film.

[1162] The depth X4 of the micropores 22 exceeds 10 nm, preferably 30 nm or more, and more preferably 75 nm or more.

[1163] Regarding the depth X4 of the above micropores 22, the cross-section (150,000 times) of the anodic oxide film 20 is observed with FE-SEM. In the obtained image, the depths of 25 micropores are measured and obtained as the arithmetic mean.

[1164] The average diameter Y3 of the micropores 22 on the surface of the anodic oxide film is preferably 10 nm or more and 30 nm or less, more preferably 11 nm or more and 25 nm or less, and still more preferably 12 nm or more and 20 nm or less.

[1165] Moreover, the average value Y4 of the maximum diameter inside the micropores is preferably 10 nm or more and 300 nm or less, more preferably 15 nm or more and 200 nm or less, and still more preferably 20 nm or more and 100 nm or less.

[1166] The ratio of the average value Y4 of the maximum diameter inside the micropores 22 to the average diameter Y3 of the micropores on the surface of the anodic oxide film is preferably 1.2 times or more and 10 times or less, more preferably 1.5 times or more and 8 times or less, and still more preferably 2 times or more and 5 times or less.

[1167] The ratio of the average value Y4 of the maximum diameter inside the micropores 22 to the average diameter Y3 of the micropores 22 is a value obtained by the following formula 1B.

[1168] Formula 1B: (Average value Y4 of the maximum diameter inside the micropores 22) / (Average diameter Y3 of the micropores 22 on the surface of the anodic oxide film)

[1169] The average diameter Y3 of the micropores on the surface of the anodic oxide film is determined by the same method as Y1 in the above method 1.

[1170] Regarding the average value Y4 of the maximum diameter inside the micropores 22, the surface of the anodic oxide film 20 is observed with an FE-SEM at a magnification of 150,000 times with N = 4 sheets. In the obtained 4 images, the maximum value (diameter) of the diameter of the micropores 22 existing within a range of 400 nm × 600 nm is measured and obtained as the arithmetic average. In addition, when the depth of the micropores 22 is deep, if necessary, the upper part of the anodic oxide film 20 is cut in a manner parallel to the anodic oxide film (for example, cut with argon), and then the surface of the anodic oxide film 20 is observed with the above FE-SEM to obtain the average diameter Y4 of the bottom of the micropores 22.

[1171] In addition, when the shape of the micropores 22 is not circular, the equivalent circle diameter is used.

[1172] The shape of the micropores 22 in Method 3 is not particularly limited. For example, there may be mentioned a substantially straight tubular shape (substantially cylindrical shape), a conical shape in which the diameter decreases toward the depth direction (thickness direction), an inverted conical shape in which the diameter increases toward the depth direction (thickness direction), a cylindrical shape with a large diameter at the central part, a cylindrical shape with a small diameter at the central part, etc., and a substantially straight tubular shape is preferred. The shape of the bottom of the micropores 22 is not particularly limited and may be a curved surface shape (concave shape) or a flat surface shape.

[1173] Further, as Figure 4B shown, it may be a shape formed by combining a cylinder with a small diameter and a cylinder with a large diameter. Regarding these cylinders, they may also be substantially straight tubular, conical, inverted conical, cylindrical with a large diameter at the central part, or cylindrical with a small diameter at the central part, and a substantially straight tubular shape is preferred. In the shape shown in FIG. 4, the shape of the bottom of the micropores 22 is not particularly limited, and it may be a curved surface (concave shape) or a flat surface.

[1174] -Other characteristics-

[1175] The density of the micropores 22 on the surface of the anodic oxide film 20 is not particularly limited, but relative to the unit area of the anodic oxide film, it is preferably 200 pores / μm 2 to 2,000 pores / μm 2 , and more preferably 200 pores / μm 2 to 1,000 pores / μm 2 .

[1176] Regarding the above density, the surface of the anodic oxide film 20 is observed with a field emission scanning electron microscope (FE-SEM) at a magnification of 150,000 times with N = 4 sheets. In the 4 obtained images, the number of micropores existing in the range of 400 nm × 600 nm is measured, and the arithmetic mean of the measured values is calculated.

[1177] In the anodic oxide film 20, the above micropores 22 may be distributed over the entire surface of the anodic oxide film, or may be distributed over at least a part, but preferably they are distributed over the entire surface.

[1178] Preferably, the micropores 22 are substantially perpendicular to the surface of the anodic oxide film 20.

[1179] And preferably, the micropores 22 are distributed in a substantially uniform state respectively.

[1180] [Manufacturing method of aluminum support]

[1181] Hereinafter, a manufacturing method of an aluminum support having an anodic oxide film in the original lithographic printing plate according to the present invention will be described.

[1182] The manufacturing method of the aluminum support having an anodic oxide film is not particularly limited, but a manufacturing method that sequentially performs the following steps is preferred.

[1183] (Roughening treatment step) A step of performing roughening treatment on an aluminum plate

[1184] (First anodic oxidation treatment step) A step of anodizing the roughened aluminum plate

[1185] (Hole-expanding treatment process) A process of bringing an aluminum plate with an anodic oxide film obtained in the first anodic oxidation treatment process into contact with an acidic aqueous solution or an alkaline aqueous solution and expanding the diameter of micropores in the anodic oxide film

[1186] (Second anodic oxidation treatment process) A process of anodizing the aluminum plate obtained in the hole-expanding treatment process

[1187] (Hydrophilic treatment process) A process of subjecting the aluminum plate obtained in the second anodic oxidation treatment process to a hydrophilic treatment

[1188] Hereinafter, each of the above processes will be described in detail. In addition, with regard to the roughening treatment process and the hydrophilic treatment process, they may not be implemented if not necessary.

[1189] According to the above manufacturing method, the aluminum support body related to the above-described mode 2 can be obtained.

[1190] Figure 5 shows a schematic cross-sectional view of an aluminum support body having anodic oxide films from the first anodic oxidation treatment process to the second anodic oxidation treatment process shown in the order of the processes.

[1191] 〔Roughening treatment process〕

[1192] The roughening treatment process is a process of subjecting the surface of the aluminum plate to a roughening treatment including an electrochemical roughening treatment. The roughening treatment process is preferably implemented before the first anodic oxidation treatment process described below, but if the surface of the aluminum plate already has a preferred surface shape, there is no need to particularly implement this process.

[1193] Regarding the roughening treatment, only the electrochemical roughening treatment can be implemented, but it can also be implemented by combining the electrochemical roughening treatment with the mechanical roughening treatment and / or the chemical roughening treatment.

[1194] In the case of combining the mechanical roughening treatment and the electrochemical roughening treatment, it is preferable to implement the electrochemical roughening treatment after the mechanical roughening treatment.

[1195] The mechanical roughening treatment is performed, for example, using Figure 8 the device shown. Specifically, for example, while supplying a pumice powder suspension (specific gravity 1.1 g / cm 3 ) as a polishing slurry to the surface of the aluminum plate, mechanical roughening treatment is performed by a rotating hard hair bundle brush. In Figure 8 , 1 is the aluminum plate, 2 and 4 are roller brushes (hard hair bundle brushes, etc.), 3 is the polishing slurry, and 5, 6, 7, and 8 are support rollers.

[1196] The electrochemical roughening treatment is preferably implemented in an aqueous solution of nitric acid or hydrochloric acid.

[1197] Regarding mechanical roughening treatment, it is usually carried out to set the surface of the aluminum plate to a surface roughness Ra of 0.35 μm to 1.0 μm.

[1198] The various conditions of the mechanical roughening treatment are not particularly limited. For example, it can be carried out according to the method described in Japanese Patent Publication No. 50-40047. The mechanical roughening treatment can be carried out by brushing and grinding the plate using a pumice suspension or by a transfer method.

[1199] The chemical roughening treatment is not particularly limited either and can be carried out according to a known method.

[1200] Preferably, the following chemical etching treatment is carried out after the mechanical roughening treatment.

[1201] The chemical etching treatment carried out after the mechanical roughening treatment is carried out for the following purposes: to smooth the edge portions of the concavo-convex shape on the surface of the aluminum plate, prevent the ink from catching on during printing, thereby improving the stain resistance (the ink removal ability during printing suspension) of the lithographic printing plate, and removing unnecessary substances such as abrasive particles remaining on the surface.

[1202] As the chemical etching treatment, etching using an acid and etching using an alkali are known. However, as a method that is particularly excellent in terms of etching efficiency, a chemical etching treatment using an alkali solution (hereinafter, also referred to as "alkali etching treatment") can be cited.

[1203] The alkali agent used in the alkali solution is not particularly limited. For example, sodium hydroxide (caustic soda), potassium hydroxide, sodium metasilicate, sodium carbonate, sodium aluminate, sodium gluconate, etc. are preferably selected.

[1204] The alkali agent may contain aluminum ions. The concentration of the alkali solution is preferably 0.01% by mass or more, more preferably 3% by mass or more, and preferably 30% by mass or less, more preferably 25% by mass or less.

[1205] The temperature of the alkali solution is preferably room temperature or higher, more preferably 30 °C or higher, and preferably 80 °C or lower, more preferably 75 °C or lower.

[1206] The etching amount is preferably 0.1 g / m 2 above, more preferably 1 g / m 2 above, and preferably 20 g / m 2 below, more preferably 10 g / m 2 below.

[1207] The treatment time preferably corresponds to the etching amount and is 2 seconds to 5 minutes. From the viewpoint of improving productivity, it is more preferably 2 seconds to 10 seconds.

[1208] In the case where an alkali etching treatment is carried out after a mechanical roughening treatment, in order to remove the products generated by the alkali etching treatment, it is preferable to carry out a chemical etching treatment (hereinafter, also referred to as "detergent treatment") using an acidic solution at a low temperature.

[1209] The acid used in the acidic solution is not particularly limited, but examples thereof include sulfuric acid, nitric acid, and hydrochloric acid. The concentration of the acidic solution is preferably 1% by mass to 50% by mass. Further, the temperature of the acidic solution is preferably 20°C to 80°C. If the concentration and temperature of the acidic solution are within this range, the stain resistance (deinking ability during printing suspension) of the lithographic printing plate is further improved.

[1210] The above roughening treatment is a treatment in which an electrochemical roughening treatment is carried out after a mechanical roughening treatment and a chemical etching treatment are carried out as required. However, even in the case where the electrochemical roughening treatment is carried out without carrying out the mechanical roughening treatment, a chemical etching treatment can be carried out using an aqueous alkali solution such as caustic soda before the electrochemical roughening treatment. Thereby, impurities and the like present near the surface of the aluminum plate can be removed.

[1211] Regarding the electrochemical roughening treatment, since it is easy to impart fine irregularities (dents) to the surface of the aluminum plate, it is suitable for producing a lithographic printing plate with excellent printability.

[1212] The electrochemical roughening treatment is carried out using direct current (DC) or alternating current (AC) in an aqueous solution mainly composed of nitric acid or hydrochloric acid.

[1213] Preferably, after the electrochemical roughening treatment, the following chemical etching treatment is carried out. There are stains and intermetallic compounds on the surface of the aluminum plate after the electrochemical roughening treatment. In the chemical etching treatment carried out after the electrochemical roughening treatment, in order to effectively remove the stains, it is preferable to first carry out a chemical etching treatment (alkali etching treatment) using an alkali solution. Among various conditions of the chemical etching treatment using an alkali solution, the treatment temperature is preferably 20°C to 80°C, and the treatment time is preferably 1 second to 60 seconds. It is preferable to contain aluminum ions in the alkali solution.

[1214] After carrying out the chemical etching treatment using an alkali solution after the electrochemical roughening treatment, in order to remove the products generated thereby, it is preferable to carry out a chemical etching treatment (detergent treatment) using an acidic solution at a low temperature.

[1215] In the case where the alkali etching treatment is not carried out after the electrochemical roughening treatment, in order to effectively remove the stains, it is also preferable to carry out the detergent treatment.

[1216] The above chemical etching treatment can be carried out by an immersion method, a spraying method, a coating method, etc., and is not particularly limited.

[1217] 〔First anodic oxidation treatment step〕

[1218] The first anodizing step is a step of forming an aluminum oxide film having micropores extending along the depth direction (thickness direction) on the surface of the aluminum plate by subjecting the aluminum plate subjected to the above roughening treatment to anodizing. As Figure 5 (A) shows, through this first anodizing treatment, an anodic aluminum oxide film 32a having micropores 33a is formed on the surface of the aluminum plate 31.

[1219] The first anodizing treatment can be carried out by a method that has been conventionally used in the art, but the manufacturing conditions are appropriately set so as to finally form the above micropores.

[1220] Specifically, the average diameter (average opening diameter) of the micropores 33a formed in the first anodizing step is preferably about 4 nm to 14 nm, more preferably 5 nm to 10 nm. If within the above range, it is easy to form the above micropores having a specified shape, and the performance of the original lithographic printing plate obtained is also more excellent.

[1221] Moreover, the depth of the micropores 33a is preferably greater than 60 nm and less than about 200 nm, more preferably 70 nm to 100 nm. If within the above range, it is easy to form the above micropores having a specified shape, and the performance of the original lithographic printing plate obtained is also more excellent.

[1222] The pore density of the micropores 33a is not particularly limited, but the pore density is preferably 50 pores / μm 2 to 4000 pores / μm 2 and more preferably 100 pores / μm 2 to 3000 pores / μm 2 . If within the above range, the UV printing durability, the ink removal ability during printing suspension, and the developability of the original lithographic printing plate of the lithographic printing plate obtained are excellent.

[1223] The film thickness of the anodic oxide film obtained through the first anodizing step is preferably 70 nm to 300 nm, more preferably 80 nm to 150 nm. If within the above range, the UV printing durability, the ink removal ability during printing suspension, the stain resistance, and the developability of the original lithographic printing plate of the lithographic printing plate obtained are excellent.

[1224] The film amount of the anodic oxide film obtained through the first anodizing step is preferably 0.1 g / m 2 to 0.3 g / m 2 and more preferably 0.12 g / m 2 to 0.25 g / m 2If within the above range, the UV printing durability, deinking ability during printing suspension, stain resistance of the lithographic printing plate, and developability of the original lithographic printing plate are excellent.

[1225] In the first anodizing treatment step, an aqueous solution such as sulfuric acid, oxalic acid, or phosphoric acid can be mainly used as the electrolytic bath. Depending on the situation, an aqueous solution or non-aqueous solution of chromic acid, sulfamic acid, benzenesulfonic acid, etc., or a combination of two or more of them can also be used. If direct current or alternating current is passed through the aluminum plate in the electrolytic bath as described above, an anodic oxide film can be formed on the surface of the aluminum plate. It is known that if the type of electrolyte is changed, the pore diameter changes significantly. Generally speaking, the pore diameter in the sulfuric acid electrolyte < the pore diameter in the oxalic acid electrolyte < the pore diameter in the phosphoric acid electrolyte.

[1226] Therefore, the electrolyte can be replaced and the treatment can be carried out twice, or the treatment devices can be connected in series of two or three, and the treatment can be carried out continuously in two or three stages to form an anodic oxide film structure.

[1227] It is possible to obtain a film with larger pores at the bottom while maintaining the pore diameter of the surface opening of the anodic oxide film by using a phosphoric acid electrolyte through the method described in Japanese Patent Application Laid-Open No. 2002-365791.

[1228] Aluminum ions can be included in the electrolytic bath. The content of aluminum ions is not particularly limited, but preferably 1 g / L to 10 g / L.

[1229] The conditions for the anodizing treatment can be appropriately set according to the electrolyte used. Generally, the concentration of the electrolyte is 1% to 80% by mass (preferably 5% to 20% by mass), the liquid temperature is 5°C to 70°C (preferably 10°C to 60°C), the current density is 0.5 A / dm 2 ~60 A / dm 2 (preferably 5 A / dm 2 ~50 A / dm 2 ), the voltage is 1 V to 100 V (preferably 5 V to 50 V), and the electrolysis time is 1 second to 100 seconds (preferably 5 seconds to 60 seconds) is appropriate.

[1230] In the above anodizing treatment, the method of anodizing at a high current density in sulfuric acid described in British Patent No. 1,412,768 is particularly preferred.

[1231] 〔Pore expansion treatment step〕

[1232] The pore expansion treatment step is a treatment (pore diameter expansion treatment) for expanding the diameter (pore diameter) of the micropores existing in the anodic oxide film formed by the above first anodizing treatment step. As Figure 5As shown in (B), through this reaming process, the diameter of the micropores 33a is enlarged to form an anodic oxide film 32b having micropores 33b with a larger average diameter.

[1233] Preferably, through the reaming process, the average diameter of the micropores 33b is enlarged to a range of 10 nm to 100 nm (preferably 15 nm to 60 nm, more preferably 18 nm to 40 nm). The micropores 33b become the part corresponding to the large-diameter pore portion 24 ( Figure 5 (A)).

[1234] Preferably, through the reaming process, the depth from the surface of the micropores 33b is adjusted to reach the same level as the above-mentioned depth A ( Figure 3A ).

[1235] The reaming process is performed by bringing the aluminum plate obtained through the above-mentioned first anodic oxidation treatment step into contact with an acidic aqueous solution or an alkaline aqueous solution. The contact method is not particularly limited, and for example, an immersion method or a spraying method can be cited. Among them, the immersion method is preferred.

[1236] When an alkaline aqueous solution is used in the reaming process, it is preferred to use at least one alkaline aqueous solution selected from sodium hydroxide, potassium hydroxide, and lithium hydroxide. The concentration of the alkaline aqueous solution is preferably 0.1% by mass to 5% by mass.

[1237] After adjusting the pH of the alkaline aqueous solution to 11 to 13, it is appropriate to bring the aluminum plate into contact with the alkaline aqueous solution for 1 second to 300 seconds (preferably 1 second to 50 seconds) under the condition of 10°C to 70°C (preferably 20°C to 50°C).

[1238] Metal salts of polybasic weak acids such as carbonates, borates, and phosphates can be included in the alkali treatment solution.

[1239] When an acidic aqueous solution is used in the reaming process, it is preferred to use an aqueous solution of an inorganic acid such as sulfuric acid, phosphoric acid, nitric acid, hydrochloric acid, or a mixture thereof. The concentration of the acidic aqueous solution is preferably 1% by mass to 80% by mass, more preferably 5% by mass to 50% by mass.

[1240] Under the condition that the liquid temperature of the acidic aqueous solution is 5°C to 70°C (preferably 10°C to 60°C), it is appropriate to bring the aluminum plate into contact with the acidic aqueous solution for 1 second to 300 seconds (preferably 1 second to 150 seconds).

[1241] Aluminum ions can be included in the alkaline aqueous solution or the acidic aqueous solution. The content of aluminum ions is not particularly limited, but preferably 1 g / L to 10 g / L.

[1242] 〔Second anodic oxidation treatment step〕

[1243] The second anodizing process is a process of forming micropores extending along the depth direction (thickness direction) by performing anodizing on the aluminum plate on which the above-mentioned hole expanding process has been performed. As Figure 5 (C) shows, through this second anodizing process, an anodic oxide film 32c having micropores 33c extending along the depth direction is formed.

[1244] Through the second anodizing process, a new hole portion is formed that communicates with the bottom of the micropores 33b with an enlarged average diameter, has an average diameter smaller than that of the micropores 33b (corresponding to the large-diameter hole portion 24), and extends along the depth direction from the communication position. The above-mentioned hole portion corresponds to the above-mentioned small-diameter hole portion 26.

[1245] In the second anodizing process, the average diameter of the newly formed hole portion is greater than 0 and less than 20 nm, and the treatment is performed in such a manner that the depth from the communication position with the large-diameter hole portion 20 falls within the above-mentioned specified range. The electrolytic bath used in the treatment is the same as that in the above-mentioned first anodizing process, and as treatment conditions, it is appropriately set according to the materials used.

[1246] The conditions for anodizing can be appropriately set according to the electrolyte used. Generally, however, the concentration of the electrolyte is 1% by mass to 80% by mass (preferably 5% by mass to 20% by mass), the liquid temperature is 5°C to 70°C (preferably 10°C to 60°C), the current density is 0.5 A / dm 2 to 60 A / dm 2 (preferably 1 A / dm 2 to 30 A / dm 2 ), the voltage is 1 V to 100 V (preferably 5 V to 50 V), and the electrolysis time is 1 second to 100 seconds (preferably 5 seconds to 60 seconds) is appropriate.

[1247] The film thickness of the anodic oxide film obtained through the second anodizing process is preferably 200 nm to 2,000 nm, more preferably 750 nm to 1,500 nm. If it is within the above range, the UV printing durability and the ink removal ability during printing suspension of the obtained lithographic printing plate are excellent.

[1248] The film amount of the anodic oxide film obtained through the second anodizing process is preferably 2.2 g / m 2 to 5.4 g / m 2 , more preferably 2.2 g / m 2 to 4.0 g / m 2 . If it is within the above range, the UV printing durability and the ink removal ability during printing suspension of the obtained lithographic printing plate, as well as the developability and scratch resistance of the original lithographic printing plate are excellent.

[1249] The ratio (film thickness 1 / film thickness 2) of the thickness of the anodic oxide film (film thickness 1) obtained by the first anodic oxidation treatment process to the thickness of the anodic oxide film (film thickness 2) obtained by the second anodic oxidation treatment process is preferably from 0.01 to 0.15, more preferably from 0.02 to 0.10. If it is within the above range, the scratch resistance of the support for the lithographic printing plate is excellent.

[1250] In order to manufacture the shape of the small-diameter hole portion 26 described above (refer to Figure 5 (A)), during the treatment of the second anodic oxidation treatment process, the applied voltage can be increased stepwise or continuously. By increasing the applied voltage, the diameter of the formed hole portion becomes larger, and as a result, a shape such as the small-diameter hole portion 26 described above can be obtained.

[1251] 〔Third anodic oxidation treatment process〕

[1252] Subsequent to the second anodic oxidation treatment process, a third anodic oxidation treatment process can be carried out.

[1253] Regarding the anodic oxidation treatment in the third anodic oxidation treatment process, it can be carried out by the same method as the second anodic oxidation treatment process, appropriately setting the liquid composition, current density, time, etc. according to the required surface state of the support.

[1254] 〔Hyd...

Claims

1. An original plate for an on-machine developing lithographic printing plate, which has a support and an image recording layer on the support, the image recording layer contains an initiator, an infrared absorber capable of supplying electrons to the initiator, and a chromogen precursor, and, The original plate for on-machine developing lithographic printing plate does not include: the case where the image recording layer simultaneously contains a tetraphenylborate represented by the following formula, an infrared absorbing dye D represented by the following formula, and a color developer S-1 represented by the following formula; and the case where the image recording layer simultaneously contains a tetraphenylborate represented by the following formula, an infrared absorbing dye D represented by the following formula, and a color developer S-4 represented by the following formula, The tetraphenylborate has the following structure: ， The infrared absorbing dye D has the following structure: ， The color developer S-1 has the following structure: ， The color developer S-4 has the following structure: ， The energy density of infrared laser exposure with a wavelength of 830 nm is 110 mJ / cm 2 When the image recording layer is exposed, the change in lightness ΔL before and after the exposure of the image recording layer is 3.0 or more. The molar extinction coefficient ε of the chromogen generated from the chromogen precursor is 35000 or more, The ring-opening rate of the chromogen precursor calculated by the following formula is 40 mol% to 99 mol%, Ring-opening rate = molar extinction coefficient when 1 molar equivalent of acid is added to the chromogen precursor / molar extinction coefficient ε of the chromogen generated from the chromogen precursor × 100, The maximum absorption wavelength of the chromogen generated from the chromogen precursor in the range of 380 nm to 750 nm is 500 nm to 650 nm, The chromogen precursor is a leuco dye having two or more electron-donating groups directly bonded to an aromatic ring and having a phthalide structure.

2. The original plate for an on-machine developing lithographic printing plate according to claim 1, wherein, the change in lightness ΔL is 5.0 or more.

3. The original plate for an on-machine developing lithographic printing plate according to claim 1 or 2, wherein, the chromogen precursor contains a compound represented by the following formula (Z-1) or formula (Z-4), ， In formula (Z-1), EDG each independently represents an electron-donating group, X represents O or NR, R represents a hydrogen atom, an alkyl group, an aryl group, or a heteroaryl group, and Y1 and Y2 each independently represent CH or N, ， In formula (Z-4), Ra1 represents a hydrogen atom, an alkyl group, or an alkoxy group, Rb1 to Rb4 each independently represent a hydrogen atom, an alkyl group, or an aryl group, Rb1 and Rb2, Rb3 and Rb4 optionally form a ring, X represents O or NR, R represents a hydrogen atom, an alkyl group, an aryl group, or a heteroaryl group, and Y1 and Y2 each independently represent CH or N.

4. The original plate for an on-machine developing lithographic printing plate according to claim 3, wherein, the chromogen precursor contains a compound represented by formula (Z-1).

5. The original plate for an on-machine developing lithographic printing plate according to claim 1 or 2, wherein, the chromogen precursor contains a compound represented by the following formula (Z-3), ， In formula (Z-3), Rb1 to Rb4 each independently represent a hydrogen atom, an alkyl group, or an aryl group, Rb1 and Rb2, Rb3 and Rb4 optionally form a ring, X represents O or NR, R represents a hydrogen atom, an alkyl group, an aryl group, or a heteroaryl group, and Y1 and Y2 each independently represent CH or N.

6. The original plate for an on-machine developing lithographic printing plate according to claim 5, wherein, Rb1 and Rb4 in formula (Z-3) are each independently an aryl group.

7. The original plate for on-machine developable lithographic printing plate according to claim 3, wherein, the color former precursor contains a compound represented by formula (Z-4).

8. The original plate for on-machine developable lithographic printing plate according to claim 1 or 2, wherein, the dehydrogenation enthalpy of all hydrogen atoms present in the molecule of the color former precursor is -6.5 kcal / mol or more.

9. The original plate for on-machine developable lithographic printing plate according to claim 1 or 2, wherein, the color former precursor does not have a structure in which a hydrogen atom is directly bonded to a nitrogen atom.

10. The original plate for on-machine developable lithographic printing plate according to claim 1 or 2, wherein, the image recording layer contains a borate compound, the value of HOMO of the infrared absorber - HOMO of the borate compound is 0.70 eV or less.

11. The original plate for on-machine developable lithographic printing plate according to claim 1 or 2, wherein, the image recording layer further contains a polymerizable compound, an onium salt compound, and an acid color former.

12. The original plate for on-machine developable lithographic printing plate according to claim 1 or 2, wherein, the image recording layer further contains addition-polymerizable resin particles having a dispersive group, the dispersive group contains a group represented by the following formula Z, -Q-W-Y type 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, and any one of W and Y has a hydrophilic structure. represents a bonding site with other structures.

13. The original plate for on-machine developable lithographic printing plate according to claim 1 or 2, wherein, the initiator contains an electron-accepting polymerization initiator, the electron-accepting polymerization initiator contains a compound represented by the following formula (II), ， In formula (II), X represents a halogen atom, and R 3 represents an aryl group.

14. The original plate for on-machine developable lithographic printing plate according to claim 1 or 2, wherein, the image recording layer further contains polyvinyl acetal as an adhesive polymer.

15. The original plate for on-machine developable lithographic printing plate according to claim 1 or 2, wherein, an overcoat layer is further provided on the image recording layer.

16. The original plate for on-machine developable lithographic printing plate according to claim 15, wherein, the overcoat layer contains a hydrophobic polymer.

17. The original plate for on-machine developable lithographic printing plate according to claim 15, wherein, the overcoat layer contains a color former precursor.

18. The original plate for on-machine developable lithographic printing plate according to claim 17, wherein, the color former precursor in the overcoat layer is an infrared absorber.

19. The original plate for on-machine developable lithographic printing plate according to claim 17, wherein, the color former precursor in the overcoat layer contains a decomposable compound that decomposes upon infrared exposure.

20. The original plate for on-machine developable lithographic printing plate according to claim 1 or 2, wherein, the support has an aluminum plate and an anodic oxide film of aluminum disposed on the aluminum plate, the anodic oxide film is located closer to the image recording layer side than the aluminum plate, the anodic oxide film has micropores extending along the depth direction from the surface on the image recording layer side, the average diameter of the micropores on the surface of the anodic oxide film exceeds 10 nm and is 100 nm or less, The brightness in the colorimetric system of the surface on the image recording layer side of the anodic oxide film is 70 to 100. ​ 21. The original plate for on-machine developable lithographic printing plate according to claim 20, wherein, The micropores are composed of a large-diameter pore portion and a small-diameter pore portion. The large-diameter pore portion extends from the surface of the anodic oxide film to a position with a depth of 10 nm to 1000 nm, and the small-diameter pore portion communicates with the bottom of the large-diameter pore portion and extends from the communication position to a position with a depth of 20 nm to 2000 nm. The average diameter of the large-diameter pore portion on the surface of the anodic oxide film is 15 nm to 100 nm. The average diameter of the small-diameter pore portion at the communication position is 13 nm or less.

22. A method for producing a lithographic printing plate, comprising: a step of exposing the on-press developable lithographic printing plate original according to any one of claims 1 to 21 into an image shape; and a step of supplying at least one selected from the group consisting of printing ink and dampening solution on a printing press to remove the image recording layer of the non-image portion.

23. A lithographic printing method, comprising: a step of exposing the on-press developable lithographic printing plate original according to any one of claims 1 to 21 into an image shape; a step of supplying at least one selected from the group consisting of printing ink and dampening solution and removing the image recording layer of the non-image portion on a printing press to produce a lithographic printing plate; and a step of performing printing using the obtained lithographic printing plate.

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