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

Abstract

The present invention provides an on-press developing type lithographic printing plate precursor and its application, wherein the on-press developing type lithographic printing plate precursor comprises a support, an image recording layer and an outermost layer in sequence, wherein the outermost layer comprises a hydrophobic polymer, and the contact angle of a water droplet dropped on the surface of the outermost layer by an aerial water drop method after 2 seconds is less than 36°.

Description

Technical Field

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

[0002] Typically, a lithographic printing plate has an oleophilic image area that receives ink during the printing process, and a hydrophilic non-image area that receives fountain solution. Lithographic printing is a method of creating a difference in the adhesion of ink on the surface of a lithographic printing plate, so that the ink is only applied to the image area, and then the ink is transferred to the printed object (e.g., paper) for printing. In lithographic printing, for example, the oleophilic image area of ​​the lithographic printing plate is used as the ink-receiving area, and the hydrophilic non-image area is used as the fountain solution-receiving area (ink-non-receiving area). To produce lithographic printing plates, a lithographic printing plate precursor (PS plate) having an oleophilic photosensitive resin layer (image recording layer) provided on a hydrophilic support has been widely used. Typically, a lithographic printing plate is obtained by making a plate using the following method: after exposing the lithographic printing plate precursor to an original image such as a high-contrast film, the portion of the image-recording layer that becomes the image portion remains, and the unnecessary image-recording layer other than the portion that becomes the image portion is dissolved away by an alkaline developer or an organic solvent, thereby exposing the surface of the hydrophilic support and forming a non-image portion.

[0003] Due to the increasing concern for the global environment, attention has been paid to environmental issues related to wastewater associated with wet processes such as development. In response to these environmental issues, the goal is to simplify development or platemaking and make it process-free. As one of the simplest production methods, a method called "on-press development" has been used. On-press development is known as a method in which an exposed lithographic printing plate precursor is mounted on a printing press without undergoing development using a conventional developer, and unnecessary portions of the image recording layer are removed at the initial stage of the printing process (for example, see Patent Document 1).

[0004] Previous technical literature

[0005] Patent Literature

[0006] Patent Document 1: International Publication No. 2019 / 243036 Summary of the Invention

[0007] Technical issues to be solved by the invention

[0008] In printing methods using lithographic printing plate precursors, there is a demand for improved ink acceptability of printing inks and improved developability during on-press development (hereinafter referred to as "on-press developability"). However, in general, ink acceptability tends to decrease in lithographic printing plate precursors with improved on-press developability, and therefore there is room for improvement in achieving a balance between ink acceptability and on-press developability.

[0009] The present invention has been accomplished in view of the above circumstances.

[0010] An object of one embodiment of the present invention is to provide an on-press developable lithographic printing plate precursor capable of achieving both ink acceptability and on-press developability.

[0011] Another embodiment of the present invention aims to provide a method for producing a lithographic printing plate using an on-press developable lithographic printing plate precursor capable of achieving both good ink acceptability and on-press developability.

[0012] Another embodiment of the present invention aims to provide a lithographic printing method using an on-press developable lithographic printing plate precursor capable of achieving both good ink acceptability and on-press developability.

[0013] Means for solving technical problems

[0014] The present invention includes the following aspects.

[0015] <1> An on-press development type lithographic printing plate precursor comprises, in order, a support, an image recording layer and an outermost layer, wherein the outermost layer comprises a hydrophobic polymer and the contact angle of a water drop dropped on the surface of the outermost layer by an aerial water drop method after 2 seconds is less than 36°.

[0016] <2> according to <1> The on-press developed lithographic printing plate precursor is heated to 110 mJ / cm 2 When exposure is performed with infrared rays having a wavelength of 830 nm at an energy density of 100 nm, the contact angle of a water droplet dropped on the surface of the outermost layer by an aerial water drop method 2 seconds later is 32° or more.

[0017] <3> An on-press developing type planographic printing plate precursor comprising a support, an image recording layer and an outermost layer in this order, wherein the contact angle of an oil droplet dropped on the surface of the outermost layer by an aerial oil drop method is 5° or more after 2 seconds, and the contact angle of the oil droplet is 110 mJ / cm 2 When exposure is performed with infrared rays having a wavelength of 830 nm at an energy density of 100 nm, the contact angle of an oil droplet dropped on the surface of the outermost layer by an aerial oil drop method is less than 10° 2 seconds after the oil droplet is dropped.

[0018] <4> according to <3> In the on-press developing type planographic printing plate precursor, the outermost layer comprises a hydrophobic polymer.

[0019] <5> according to <1> to <2> and <4> The on-press development type lithographic printing plate precursor according to any one of the preceding claims, wherein the area occupied by the hydrophobic polymer on the surface of the outermost layer is less than 40%.

[0020] <6> according to <1> to <2> and <4> to <5> The on-press developable lithographic printing plate precursor according to any one of the preceding claims, wherein the hydrophobic polymer is in the form of particles.

[0021] <7> according to <1> to <2> and <4> to <6> The on-press developable lithographic printing plate precursor according to any one of the preceding claims, wherein the hydrophobic polymer has a glass transition temperature of 60° C. or higher.

[0022] <8> according to <1> to <7> The on-press development type lithographic printing plate precursor according to any one of the preceding claims, wherein the outermost layer comprises a hydrophilic polymer.

[0023] <9> according to <1> to <2> and <4> to <7> The on-press developable lithographic printing plate precursor according to any one of the preceding claims, wherein the outermost layer comprises a hydrophilic polymer, and the content of the hydrophilic polymer is greater than the content of the hydrophobic polymer.

[0024] <10> according to <1> to <9> The on-press developable lithographic printing plate precursor according to any one of the preceding claims, wherein the outermost layer contains a color-changing compound.

[0025] <11> according to <10> The on-press developed lithographic printing plate precursor is heated to 110 mJ / cm 2 When the exposure is performed with infrared rays having a wavelength of 830 nm at an energy density of , a brightness change ΔL before and after the exposure is 2.0 or more.

[0026] <12> according to <10> or <11> In the on-press developing type planographic printing plate precursor, the color-changing compound includes a compound that develops color upon exposure to infrared rays.

[0027] <13> according to <10> to <12> The on-press developable lithographic printing plate precursor according to any one of the preceding claims, wherein the color-changing compound includes a decomposable compound that decomposes upon exposure to infrared rays.

[0028] <14> according to <10> to <13> The on-press developable lithographic printing plate precursor according to any one of the preceding claims, wherein the color-changing compound is a cyanine pigment.

[0029] <15> according to <10> to <14> The on-press development type lithographic printing plate precursor according to any one of the preceding claims, wherein the color-changing compound is a compound represented by the following formula 1-1.

[0030] [Chemical Formula 1]

[0031]

[0032] In formula 1-1, R 1represents a group represented by any one of the following formulas 2 to 4, R 11 ~R 18 Each independently represents a hydrogen atom, a halogen atom, -R a 、-OR b 、-SR c or -NR d R e , R a ~R e Each independently represents a hydrocarbon group, A1, A2 and multiple R 11 ~R 18 They 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 represents an integer from 0 to 5, n 11 and n 12 The total of n is 2 or more, 13 and n 14 Each independently represents 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.

[0033] [Chemical Formula 2]

[0034]

[0035] In formula 2 to formula 4, R 20 、R 30 、R 41 and R 42 Each independently represents an alkyl group or an aryl group, Zb represents a counter ion for neutralizing the charge, and the wavy line represents a bonding site with L.

[0036] <16> according to <10> to <15> The on-press development type lithographic printing plate precursor according to any one of the preceding claims, wherein the color-changing compound is a compound represented by the following formula 1-2.

[0037] [Chemical Formula 3]

[0038]

[0039] In formula 1-2, R 1 represents a group represented by any one of the following formulas 2 to 4, R 19 ~R 22 Each independently represents a hydrogen atom, a halogen atom, -R a 、-OR b 、-CN、-SR c or -NR d Re , R 23 and R 24 Each independently represents -R a , R a ~R e Each independently represents a hydrocarbon group, R 19 With R 20 、R 21 With R 22 or R 23 With R 24 They can be linked to form a monocyclic or polycyclic ring, and L represents an oxygen atom, a sulfur atom or -NR 10 -, R 10 represents a hydrogen atom, an alkyl group or an aryl group, R d1 ~R d4 、W 1 and W 2 Each independently represents an alkyl group which may have a substituent, and Za represents a counter ion for neutralizing the charge.

[0040] [Chemical Formula 4]

[0041]

[0042] In formula 2 to formula 4, R 20 、R 30 、R 41 and R 42 Each independently represents an alkyl group or an aryl group, Zb represents a counter ion for neutralizing the charge, and the wavy line represents a bonding site with L.

[0043] <17> according to <10> to <16> The on-press developable lithographic printing plate precursor according to any one of the preceding claims, wherein the color-changing compound is a compound represented by any one of the following formulas 1-3 to 1-7.

[0044] [Chemical Formula 5]

[0045]

[0046] In formulas 1-3 to 1-7, R 1 represents a group represented by any one of the following formulas 2 to 4, R 19 ~R 22 Each independently represents a hydrogen atom, a halogen atom, -R a 、-OR b 、-CN、-SR c or -NR d R e , R 23 and R 24 Each independently represents -R a , R 25 and R26 Each independently represents a hydrogen atom, a halogen atom or -R a , R a ~R e Each independently represents a hydrocarbon group, R 19 With R 20 、R 21 With R 22 、R 23 With R 24 or R 25 With R 26 They can be linked to form a monocyclic or polycyclic ring, and L represents an oxygen atom, a sulfur atom or -NR 10 -, R 10 represents a hydrogen atom, an alkyl group or an aryl group, R d1 ~R d4 、W 1 and W 2 Each independently represents an alkyl group which may have a substituent, and Za represents a counter ion for neutralizing the charge.

[0047] [Chemical Formula 6]

[0048]

[0049] In formula 2 to formula 4, R 20 、R 30 、R 41 and R 42 Each independently represents an alkyl group or an aryl group, Zb represents a counter ion for neutralizing the charge, and the wavy line represents a bonding site with L.

[0050] <18> according to <16> or <17> The on-press developing type planographic printing plate precursor, wherein the W 1 And the above W 2 Each independently represents an alkyl group having a substituent, and the substituent is a group having at least -(OCH2CH2)-, a sulfo group, a salt of a sulfo group, a carboxyl group, or a salt of a carboxyl group.

[0051] <19> according to <1> to <18> The on-press developable lithographic printing plate precursor according to any one of the preceding claims, wherein the image recording layer comprises at least one selected from the group consisting of an electron-accepting polymerization initiator and an electron-donating polymerization initiator.

[0052] <20> according to <19> In the on-press developing type planographic printing plate precursor, the electron-accepting polymerization initiator comprises a compound represented by the following formula (II).

[0053] [Chemical Formula 7]

[0054]

[0055] In formula (II), X represents a halogen atom, R 3 Represents an aryl group.

[0056] <21> according to <1> to <18> The on-press developable lithographic printing plate precursor according to any one of the preceding claims, wherein the image recording layer comprises a compound in which an electron-donating polymerization initiator and an electron-accepting polymerization initiator form an ion pair.

[0057] <22> according to <19> to <21> The on-press developable lithographic printing plate precursor according to any one of the preceding claims, wherein the image recording layer contains an infrared absorber, and the value of the HOMO energy level of the infrared absorber minus the HOMO energy level of the electron-donating polymerization initiator is 0.70 eV or less.

[0058] <23> according to <19> to <22> The on-press developable lithographic printing plate precursor according to any one of the preceding claims, wherein the image recording layer contains an infrared absorber, and the value of the LUMO energy level of the electron-accepting polymerization initiator minus the LUMO energy level of the infrared absorber is 1.00 eV or less.

[0059] <24> according to <1> to <23> The on-press development type lithographic printing plate precursor according to any one of the preceding claims, wherein the image recording layer contains a polymerizable compound having 7 or more polymerizable groups.

[0060] <25> according to <1> to <24> The on-press development type lithographic printing plate precursor according to any one of the preceding claims, wherein the image recording layer contains a polymerizable compound having 10 or more polymerizable groups.

[0061] <26> according to <1> to <25> The on-machine development type lithographic printing plate precursor described in any one of the preceding claims, wherein the support body comprises an aluminum plate and an anodized aluminum film disposed on the aluminum plate, the anodized aluminum film being located closer to the image recording layer than the aluminum plate, the anodized aluminum film having micropores extending from the surface on the image recording layer side in a depth direction, and the average diameter of the micropores at the surface of the anodized aluminum film being greater than 10 nm and less than 100 nm.

[0062] <27> according to <26> The on-machine development type lithographic printing plate precursor, wherein the above-mentioned micropores have a large-diameter pore portion and a small-diameter pore portion, the above-mentioned large-diameter pore portion extends from the surface of the above-mentioned anodized film to a depth of 10nm to 1,000nm, the above-mentioned small-diameter pore portion is connected to the bottom of the above-mentioned large-diameter pore portion and extends from the connection position with the above-mentioned large-diameter pore portion to a depth of 20nm to 2,000nm, the average diameter of the above-mentioned large-diameter pore portion at the surface of the above-mentioned anodized film is 15nm to 100nm, and the average diameter of the above-mentioned small-diameter pore portion at the above-mentioned connection position is less than 13nm.

[0063] <28> A method for producing a lithographic printing plate, comprising: <1> to <27> The step of exposing the on-press developed lithographic printing plate precursor to an image shape; and supplying at least one selected from printing ink and fountain solution on the printing press to remove the image recording layer in the non-image area.

[0064] <29> A lithographic printing method comprising: <1> to <27> The process of exposing the on-press developed lithographic printing plate precursor to an image shape as described in any one of the above; the process of supplying at least one selected from printing ink and fountain solution on the printing press to remove the image recording layer of the non-image part to make a lithographic printing plate; and the process of printing using the obtained above-mentioned lithographic printing plate.

[0065] Effects of the Invention

[0066] According to one embodiment of the present invention, an on-press developable lithographic printing plate precursor capable of achieving both ink acceptability and on-press developability can be provided.

[0067] According to another embodiment of the present invention, there is provided a method for producing a lithographic printing plate using an on-press developable lithographic printing plate precursor capable of achieving both good ink acceptability and on-press developability.

[0068] According to another embodiment of the present invention, there is provided a lithographic printing method using an on-press developable lithographic printing plate precursor capable of achieving both ink acceptability and on-press developability. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] Figure 1 This is a schematic cross-sectional view of a support body according to one embodiment.

[0070] Figure 2 It is a schematic cross-sectional view of a support body according to another embodiment.

[0071] Figure 3 This is a schematic diagram showing an example of an anodizing treatment apparatus. DETAILED DESCRIPTION

[0072] The following describes the present invention in detail. The following description of the components is based on representative embodiments of the present invention, but the present invention is not limited to these embodiments.

[0073] In this specification, "to" indicating a numerical range is used to mean that the numerical values ​​described before and after it are included as the lower limit and the upper limit.

[0074] Regarding the numerical ranges described in the present invention, the upper limit or lower limit of a numerical range may be replaced by the upper limit or lower limit of another numerical range. In addition, the upper limit or lower limit of the numerical range in the present invention may be replaced by the value shown in the Examples.

[0075] Regarding the notation of groups (atomic groups) in the present invention, the notation "unsubstituted" and "unsubstituted" include both groups without substitution and groups with substitution. For example, "alkyl" includes not only alkyl groups without substitution (i.e., unsubstituted alkyl groups) but also alkyl groups with substitution (substituted alkyl groups).

[0076] In the present invention, “(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.

[0077] The term "process" in the present invention includes not only independent processes but also processes that cannot be clearly distinguished from other processes as long as the intended purpose of the process can be achieved.

[0078] In the present invention, "mass %" and "weight %" have the same meaning, and "parts by mass" and "parts by weight" have the same meaning.

[0079] In the present invention, a combination of two or more preferred embodiments is a more preferred embodiment.

[0080] Unless otherwise specified, the weight average molecular weight (Mw) and number average molecular weight (Mn) in the present invention are molecular weights measured using a gel permeation chromatography (GPC) analyzer using TSKgel GMHxL, TSKgel G4000HxL, and TSKgel G2000HxL (all trade names manufactured by TOSOH CORPORATION) columns, using THF (tetrahydrofuran) as a solvent, and a differential refractometer, using polystyrene-equivalent standard substances.

[0081] In the present invention, the term "lithographic printing plate precursor" includes not only lithographic printing plate precursors but also discarded plate precursors.

[0082] In the present invention, the term "lithographic printing plate" encompasses not only lithographic printing plates produced by subjecting lithographic printing plate precursors to exposure, development, and other procedures as needed, but also discarded plates. Discarded plates do not necessarily require exposure and development. Furthermore, discarded plates refer to lithographic printing plate precursors used to mount on unused plate cylinders, for example, when printing a portion of a page in single or two-color format in color newspaper printing.

[0083] In the present invention, "printing durability" refers to the number of printable sheets of a lithographic printing plate. Printing durability when ultraviolet curable ink (UV ink) is used as the ink for printing is also referred to as "UV printing durability."

[0084] <On-press developed lithographic printing plate precursor>

[0085] An on-press development type lithographic printing plate precursor according to one embodiment of the present invention includes the following embodiments.

[0086] The on-press developing type lithographic printing plate precursor involved in the first embodiment has a support, an image recording layer and an outermost layer in this order, the outermost layer contains a hydrophobic polymer, and the contact angle of a water drop 2 seconds after being dropped on the surface of the outermost layer by an air water drop method is less than 36°. According to the on-press developing type lithographic printing plate precursor involved in the first embodiment, a lithographic printing plate precursor that can take into account both ink receptivity and on-press development properties can be provided. The reason why the on-press developing type lithographic printing plate precursor involved in the first embodiment exerts the above-mentioned effect is speculated as follows. In the on-press developing type lithographic printing plate precursor involved in the first embodiment, the outermost layer contains a hydrophobic polymer, and the contact angle of a water drop 2 seconds after being dropped on the surface of the outermost layer by an air water drop method is less than 36°. According to the above-mentioned structure, the deterioration of ink receptivity can be suppressed by the hydrophobic polymer contained in the outermost layer, and the on-press development properties can be improved by the protective layer having high hydrophilicity. Thus, a lithographic printing plate precursor that can take into account both ink receptivity and on-press development properties can be provided.

[0087] The on-press development type planographic printing plate precursor according to the second embodiment comprises a support, an image recording layer and an outermost layer in this order, and the contact angle of the oil droplet dropped on the surface of the outermost layer by the air oil drop method is 5° or more after 2 seconds, and the oil droplet is subjected to a heat treatment at 110 mJ / cm 2 When the exposure is performed based on infrared rays with a wavelength of 830nm at an energy density of , the contact angle of the oil droplet after 2 seconds from the time it is dropped on the surface of the above-mentioned outermost layer by the air oil drop method is less than 10°. According to the on-press developing type lithographic printing plate precursor involved in the second embodiment, a lithographic printing plate precursor that can take into account both ink acceptability and on-press developability can be provided. The reason why the on-press developing type lithographic printing plate precursor involved in the second embodiment exerts the above-mentioned effect is speculated as follows. In the on-press developing type lithographic printing plate precursor involved in the second embodiment, the contact angle of the oil droplet after 2 seconds from the time it is dropped on the surface of the outermost layer by the air oil drop method is 5° or more, and the contact angle of the oil droplet after 2 seconds from the time it is dropped on the surface of the outermost layer by the air oil drop method is 110mJ / cm 2When exposed to infrared light with a wavelength of 830 nm at an energy density of 100 nm, the contact angle of an oil droplet dropped onto the surface of the outermost layer by an aerial oil drop method is less than 10° 2 seconds after the droplet is dropped. With this structure, degradation of ink acceptability can be suppressed by suppressing or improving the hydrophobicity of the protective layer in the exposed area, while on-press developability can be improved by providing high hydrophilicity in the protective layer in the unexposed area. This provides a lithographic printing plate precursor that achieves both good ink acceptability and good on-press developability.

[0088] The following describes an on-press developable lithographic printing plate precursor in detail. Hereinafter, the "on-press developable lithographic printing plate precursor" may be referred to simply as the "lithographic printing plate precursor." Unless otherwise specified, the technical matters described below can be applied to either or both of the on-press developable lithographic printing plate precursor of the first embodiment and the on-press developable lithographic printing plate precursor of the second embodiment. Technical matters described in one embodiment can be applied to other embodiments without departing from the scope of the present invention.

[0089] <<Outermost layer>>

[0090] An on-press developable lithographic printing plate precursor according to one embodiment of the present invention comprises an outermost layer. This outermost layer can function, for example, as a protective layer. For example, the outermost layer can function to inhibit image formation inhibition reactions by blocking oxygen, prevent scratches in the image recording layer, and prevent ablation during high-intensity laser exposure. Layers having these properties are described, for example, in U.S. Patent No. 3,458,311 and Japanese Patent Publication No. 55-49729.

[0091] [Contact angle]

[0092] In the first embodiment, the contact angle of the water droplets dropped on the surface of the outermost layer by the aerial water drop method (hereinafter also referred to as "the contact angle of the water droplets in the unexposed portion") is less than 36° after 2 seconds. By having the contact angle of the water droplets be less than 36°, the on-machine developability can be improved. The contact angle of the water droplets in the unexposed portion is preferably less than 30°, more preferably less than 28°, and particularly preferably less than 26°. There is no restriction on the lower limit of the contact angle of the water droplets in the unexposed portion. The contact angle of the water droplets in the unexposed portion may exceed 0°, be greater than 10°, or be greater than 20°. Unless otherwise specified, the "surface of the outermost layer" refers to the surface of the outermost layer that faces the side opposite to the surface facing the image recording layer.

[0093] In the first embodiment, from the viewpoint of ink adhesion, the ink was injected at 110 mJ / cm 2The contact angle of water droplets dropped on the surface of the outermost layer by the air drop method 2 seconds after exposure based on infrared rays with a wavelength of 830 nm at an energy density of 100 nm (hereinafter also referred to as "the contact angle of water droplets in the exposed portion") is preferably 28° or more, more preferably 32° or more. From the viewpoint of ink adherence, the contact angle of water droplets in the exposed portion may be 40° or more, 45° or more, or 50° or more. There is no upper limit to the contact angle of water droplets in the exposed portion. The contact angle of water droplets in the exposed portion may be 70° or less or 60° or less.

[0094] In the first embodiment, from the viewpoint of on-machine developability and ink adherence, the contact angle of the water droplets in the exposed portion is preferably larger than the contact angle of the water droplets in the unexposed portion. For example, the value of the contact angle of the water droplets in the exposed portion minus the contact angle of the water droplets in the unexposed portion is preferably 2° or more. From the viewpoint of on-machine developability and ink adherence, the value of the contact angle of the water droplets in the exposed portion minus the contact angle of the water droplets in the unexposed portion may be 5° or more, 10° or more, or 15° or more. There is no upper limit to the value of the contact angle of the water droplets in the exposed portion minus the contact angle of the water droplets in the unexposed portion. The value of the contact angle of the water droplets in the exposed portion minus the contact angle of the water droplets in the unexposed portion may be 20° or less.

[0095] In the second embodiment, the contact angle of the oil droplets 2 seconds after being dropped on the surface of the outermost layer by the aerial oil drop method (hereinafter also referred to as "the contact angle of the oil droplets in the unexposed portion") is 5° or more. By having the contact angle of the oil droplets in the unexposed portion be 5° or more, the on-machine developability can be improved. The contact angle of the oil droplets in the unexposed portion is preferably 6° or more, more preferably 8° or more. The contact angle of the oil droplets in the unexposed portion may be 10° or more or 15° or more. There is no upper limit to the contact angle of the oil droplets in the unexposed portion. The contact angle of the oil droplets in the unexposed portion may be less than 20°, less than 15° or less than 10°.

[0096] In the second embodiment, the 2 When exposure is performed based on infrared rays with a wavelength of 830 nm at an energy density of 100 nm, the contact angle of the oil droplets dropped on the surface of the outermost layer by the aerial oil drop method after 2 seconds (hereinafter also referred to as "the contact angle of the oil droplets in the exposed portion") is less than 10°. By making the contact angle of the oil droplets in the exposed portion less than 10°, the ink adherence can be improved. From the viewpoint of ink adherence, the contact angle of the oil droplets in the exposed portion may be less than 6°, less than 4°, or less than 2°. There is no lower limit to the contact angle of the oil droplets in the exposed portion. The contact angle of the oil droplets in the exposed portion may exceed 0° or be greater than 1°.

[0097] In the second embodiment, from the viewpoint of on-press developability and ink adherence, the contact angle of the oil droplets in the exposed portion is preferably smaller than the contact angle of the oil droplets in the unexposed portion. For example, the value of the contact angle of the oil droplets in the exposed portion minus the contact angle of the oil droplets in the unexposed portion is preferably -2° or less. From the viewpoint of on-press developability and ink adherence, the value of the contact angle of the oil droplets in the exposed portion minus the contact angle of the oil droplets in the unexposed portion may be -4° or less, -6° or less, or -8° or less. There is no upper limit to the value of the contact angle of the oil droplets in the exposed portion minus the contact angle of the oil droplets in the unexposed portion. The value of the contact angle of the oil droplets in the exposed portion minus the contact angle of the oil droplets in the unexposed portion may be -15° or more or -10° or more.

[0098] In the present invention, the contact angle of a water droplet is measured using a fully automatic contact angle meter (e.g., DM-501 manufactured by Kyowa Interface Science Co., Ltd.) as a measuring instrument. The contact angle of a water droplet dropped onto the surface of a measurement object at 25°C (the contact angle measured 2 seconds after the droplet was dropped) is measured. The contact angles are measured at three or more locations on the surface of the same measurement object, and the average of the measured values ​​is calculated.

[0099] In the present invention, the contact angle of an oil droplet is measured using a fully automatic contact angle meter (e.g., DM-501 manufactured by Kyowa Interface Science Co., Ltd.) as the measuring instrument. The contact angle of linseed oil dropped onto the surface of a measurement object at 25°C (the contact angle measured 2 seconds after the droplet was applied) is measured. Contact angles are measured at three or more locations on the surface of the same measurement object, and the average of the measured values ​​is calculated.

[0100] In the present invention, 110 mJ / cm 2 Exposure was performed using infrared light with a wavelength of 830 nm using the following method. A Luxel PLATESETTER T-9800 manufactured by FUJIFILM Global Graphic Systems Co., Ltd., equipped with an infrared semiconductor laser with a wavelength of 830 nm, was used under conditions of 99.5% output, 220 rpm (revolutions per minute) for the external drum, and 2,400 dpi (dots per inch, 1 inch = 25.4 mm) for the resolution (energy density: 110 mJ / cm 2 The exposure was performed under an environment of 25° C. and 50% RH (relative humidity).

[0101] The contact angle of a water droplet and the contact angle of an oil droplet on the surface of the outermost layer can be adjusted, for example, by adjusting the composition of the outermost layer. For example, the contact angle of a water droplet and the contact angle of an oil droplet can be adjusted by using a hydrophobic polymer or a hydrophilic polymer, as described later, and adjusting the content of the hydrophobic polymer or the hydrophilic polymer, as described later. However, the method for adjusting the contact angle is not limited to the method described above. Known methods can be used to adjust the contact angle.

[0102] [polymer]

[0103] The outermost layer preferably contains a polymer. Examples of the polymer include hydrophobic polymers and hydrophilic polymers.

[0104] In the first embodiment, the outermost layer contains a hydrophobic polymer. The outermost layer containing a hydrophobic polymer can improve ink receptivity. In the first embodiment, from the perspectives of ink receptivity and on-press development, the outermost layer preferably contains a hydrophobic polymer and a hydrophilic polymer.

[0105] In the second embodiment, from the perspective of ink receptivity, the outermost layer preferably comprises a hydrophobic polymer. In the second embodiment, from the perspective of on-press developability, the outermost layer preferably comprises a hydrophilic polymer. In the second embodiment, from the perspective of ink receptivity and on-press developability, the outermost layer preferably comprises a hydrophobic polymer and a hydrophilic polymer.

[0106] Hereinafter, the hydrophobic polymer and the hydrophilic polymer will be described in detail.

[0107] (Hydrophobic polymer)

[0108] From the viewpoint of ink receptivity, the outermost layer preferably contains a hydrophobic polymer. In the present invention, the "hydrophobic polymer" refers to a polymer having a solubility in water at 25°C of 5% by mass or less.

[0109] Examples of the hydrophobic polymer include polyethylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyalkyl (meth)acrylates (e.g., polymethyl (meth)acrylate, polyethyl (meth)acrylate, and polybutyl (meth)acrylate), fluorine-containing (meth)acrylic resins, and copolymers obtained by combining monomers serving as raw materials for these polymers. The hydrophobic polymer preferably includes a styrene-acrylic acid copolymer.

[0110] The glass transition temperature (Tg) of the hydrophobic polymer is preferably 30°C or higher, more preferably 60°C or higher, and particularly preferably 70°C or higher. There is no upper limit on the glass transition temperature of the hydrophobic polymer. The glass transition temperature of the hydrophobic polymer may be 150°C or lower, or 120°C or lower.

[0111] The glass transition temperature of the polymer is measured using differential scanning calorimetry (DSC). The specific measurement method is carried out in accordance with the method described in "JIS K 7121 (1987)" or "JIS K 6240 (2011)". An appropriate JIS standard is selected according to the composition of the polymer. The glass transition temperature in the present invention uses the extrapolated glass transition start temperature (hereinafter also referred to as "Tig".). The following is a more specific description of the method for measuring the glass transition temperature. In the measurement of the glass transition temperature, a temperature of about 50°C lower than the predicted glass transition temperature of the polymer is maintained until the device stabilizes, and then heated to a temperature of about 30°C higher than the temperature at which the glass transition ends at a heating rate of 20°C / min, thereby producing a differential thermal analysis (DTA) curve or a DSC curve. The extrapolated glass transition starting temperature (Tig), that is, the glass transition temperature (Tg) in the present invention, is determined as the temperature of the intersection of a straight line obtained by extending the low-temperature side baseline to the high-temperature side in a DTA curve or a DSC curve and a tangent line drawn at the point where the gradient of the curve in the step-like change portion of the glass transition is maximum.

[0112] The form of the hydrophobic polymer is preferably particles. By the form of the hydrophobic polymer being particles, the hydrophobicity of the surface of the outermost layer can be further improved. For example, the particulate hydrophobic polymer can form a sea-island structure with the hydrophobic polymer as an island region on the surface of the outermost layer. The sea-island structure as described above can contribute to improving hydrophobicity. In the present invention, the form of the hydrophobic polymer whose outline is confirmed by surface observation (i.e., looking down) of the outermost layer is regarded as a particle. The contour shape of the hydrophobic polymer confirmed by surface observation of the outermost layer is not limited to a perfect circle, for example, it can be an ellipse, a polygon or an irregular shape. In the surface observation of the outermost layer, as needed, the observation method used in the determination method of "occupancy area ratio of hydrophobic polymer" described later can be utilized.

[0113] From the perspective of on-press developability, the area occupied by the hydrophobic polymer on the surface of the outermost layer is preferably 50% or less, more preferably less than 40%. The area occupied by the hydrophobic polymer on the surface of the outermost layer may be 35% or less, 30% or less, 25% or less, or 20% or less. From the perspective of ink acceptability, the area occupied by the hydrophobic polymer on the surface of the outermost layer is preferably 5% or more.

[0114] The area occupied by the hydrophobic polymer on the surface of the outermost layer is measured by the following method. After a 3 nm carbon film or a 3 nm Pt-Pd film is applied to the surface of the object to be measured as a conductive treatment, a reflected electron image is observed at an accelerating voltage of 5 kV to 10 kV using a SU8010 FE-SEM manufactured by Hitachi High-Tech Co., Ltd. For images taken at a total of 3 locations at an observation magnification of 1,000 to 10,000 times (the magnification is adjusted according to the size of the hydrophobic polymer being observed), the area occupied by the hydrophobic polymer is calculated by binarization using image processing software (e.g., ImageJ) and utilizing the contrast difference between the hydrophobic polymer (e.g., convex portion) and the surrounding area of ​​the hydrophobic polymer. The area occupied by the hydrophobic polymer is calculated by dividing the "area of ​​the hydrophobic polymer" by the "area of ​​the field of view (the total value of the area of ​​the hydrophobic polymer and the area of ​​the region other than the hydrophobic polymer)". However, when the hydrophobic polymer cannot be observed in the image obtained by the above method, the content of the hydrophobic polymer in the outermost layer (unit: mass %) is taken as the area occupied by the hydrophobic polymer.

[0115] The outermost layer may contain one type of hydrophobic polymer alone or two or more types of hydrophobic polymers.

[0116] From the perspective of on-press developability, the content of the hydrophobic polymer is preferably 50% by mass or less, more preferably less than 40% by mass, relative to the total mass of the outermost layer. The content of the hydrophobic polymer relative to the total mass of the outermost layer may be 35% by mass or less, 30% by mass or less, 25% by mass or less, or 20% by mass or less. From the perspective of ink acceptability, the content of the hydrophobic polymer relative to the total mass of the outermost layer is preferably 5% by mass or more.

[0117] (Hydrophilic polymer)

[0118] From the viewpoint of on-press developability, the outermost layer preferably contains a hydrophilic polymer. In the present invention, the "hydrophilic polymer" refers to a polymer having a solubility in water at 25°C exceeding 5% by mass.

[0119] Examples of the hydrophilic polymer include starch phosphate, polyvinyl alcohol, modified polyvinyl alcohol, polyvinyl pyrrolidone, cellulose derivatives, polyethylene glycol, and poly(meth)acrylonitrile. As the modified polyvinyl alcohol, acid-modified polyvinyl alcohol having a carboxyl group or a sulfonic group can be preferably used. Specifically, the modified polyvinyl alcohols described in Japanese Patent Application Laid-Open No. 2005-250216 and Japanese Patent Application Laid-Open No. 2006-259137 can be mentioned. Examples of the cellulose derivative include methylcellulose, hydroxypropyl methylcellulose, and carboxymethylcellulose.

[0120] In one embodiment, the hydrophilic polymer preferably includes at least one selected from modified polyvinyl alcohol and cellulose derivatives.

[0121] In one embodiment, the hydrophilic polymer preferably comprises polyvinyl alcohol. Among polyvinyl alcohols, polyvinyl alcohol having a saponification degree of 50% or greater is more preferred. The saponification degree is preferably 60% or greater, more preferably 70% or greater, and particularly preferably 85% or greater. There is no upper limit on the saponification degree. The saponification degree may be 100% or less. The saponification degree is measured according to the method described in JIS K6726:1994.

[0122] In one embodiment, the hydrophilic polymer preferably comprises polyvinyl pyrrolidone. It is also preferable to use polyvinyl alcohol and polyvinyl pyrrolidone in combination as the hydrophilic polymer.

[0123] The outermost layer may contain one type of hydrophilic polymer alone or two or more types of hydrophilic polymers.

[0124] From the perspective of on-press developability, the content of the hydrophilic polymer relative to the total mass of the outermost layer is preferably 50% by mass or greater, more preferably 60% by mass or greater. From the perspective of ink adherence, the content of the hydrophilic polymer relative to the total mass of the outermost layer is preferably less than 100% by mass, more preferably less than 90% by mass.

[0125] When the outermost layer contains a hydrophobic polymer and a hydrophilic polymer, the content of the hydrophilic polymer is preferably greater than the content of the hydrophobic polymer. By having a higher content of the hydrophilic polymer than the hydrophobic polymer, on-press developability can be further improved without deteriorating ink acceptability. Specifically, the content of the hydrophilic polymer is preferably 1.2 times or more, more preferably 1.5 times or more, and particularly preferably 2.0 times or more, of the content of the hydrophobic polymer, based on mass. There is no upper limit on the ratio of the content of the hydrophilic polymer to the content of the hydrophobic polymer. The content of the hydrophilic polymer can be 10.0 times or less of the content of the hydrophobic polymer, based on mass.

[0126] [Color-changing compounds]

[0127] The outermost layer preferably contains a color-changing compound. In the present invention, a "color-changing compound" refers to a compound whose absorption in the visible light region (wavelength: 400 nm or more and less than 750 nm) changes due to infrared exposure. That is, in the present invention, "color change" refers to a change in absorption in the visible light region (wavelength: 400 nm or more and less than 750 nm) due to infrared exposure. As the color-changing compound, for example, there can be mentioned (1) a compound whose absorption in the visible light region increases due to infrared exposure compared to before infrared exposure, (2) a compound that has absorption in the visible light region due to infrared exposure, and (3) a compound that has no absorption in the visible light region due to infrared exposure. In addition, in the present invention, "infrared light" refers to light in the wavelength region of 750 nm to 1 mm, preferably light in the wavelength region of 750 nm to 1,400 nm.

[0128] The color-changing compound preferably includes a compound that develops color due to infrared exposure. Furthermore, the color-changing compound preferably includes a decomposable compound that decomposes due to infrared exposure, more preferably includes a decomposable compound that decomposes by heat, electron transfer, or both caused by infrared exposure. Specifically, the color-changing compound is preferably a compound that decomposes due to infrared exposure (more preferably decomposes by heat, electron transfer, or both caused by infrared exposure), and has an increased absorption in the visible light region or a compound that has absorption in the visible light region compared to before infrared exposure. Here, "decomposition by electron transfer" refers to the electron transfer from the HOMO (highest occupied molecular orbital) of the color-changing compound to the LUMO (lowest unoccupied molecular orbital) by infrared exposure to an electron-accepting group (a group with a potential close to LUMO) in the molecule, followed by decomposition.

[0129] The following describes a degradable compound, which is a type of color-changing compound. For example, any degradable compound can absorb at least a portion of light in the infrared wavelength range (the wavelength range of 750 nm to 1 nm, preferably the wavelength range of 750 nm to 1,400 nm) and decompose. The degradable compound is preferably a compound having a maximum absorption wavelength in the wavelength range of 750 nm to 1,400 nm. Specifically, the degradable compound is preferably a compound that decomposes upon exposure to infrared light to produce a compound having a maximum absorption wavelength in the wavelength range of 500 nm to 600 nm.

[0130] From the viewpoint of improving the visibility of the exposed portion, the decomposable compound as one of the color-changing compounds is preferably a cyanine dye, and more preferably a compound having a group that decomposes upon exposure to infrared light (specifically, R in the following formulas 1-1 to 1-7) 1 ) anthocyanin pigments.

[0131] (Compound represented by Formula 1-1)

[0132] From the viewpoint of improving the visibility of the exposed portion, the decomposable compound, which is one type of the color-changing compound, is preferably a compound represented by the following formula 1-1.

[0133] [Chemical Formula 8]

[0134]

[0135] In formula 1-1, R 1 represents a group represented by any one of the following formulas 2 to 4, R 11 ~R 18 Each independently represents a hydrogen atom, a halogen atom, -R a 、-OR b 、-SR c or -NR d R e , R a ~R e Each independently represents a hydrocarbon group, A1, A2 and multiple R 11 ~R 18 They 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 represents an integer from 0 to 5, n 11 and n 12 The total of n is 2 or more, 13 and n 14 Each independently represents 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.

[0136] [Chemical Formula 9]

[0137]

[0138] In formula 2 to formula 4, R 20 、R 30 、R 41 and R 42 Each independently represents an alkyl group or an aryl group, Zb represents a counter ion for neutralizing the charge, and the wavy line represents a bonding site with L.

[0139] If the compound represented by Formula 1-1 is exposed to infrared light, R 1 -L bond breaks, L becomes =O, =S or =NR 10 Through the process described above, the compound represented by Formula 1-1 changes color.

[0140] In formula 1-1, R 1 represents a group represented by any one of the above-mentioned formulae 2 to 4. Hereinafter, the group represented by formula 2, the group represented by formula 3, and the group represented by formula 4 will be described respectively.

[0141] In formula 2, R 20 represents an alkyl group or an aryl group, and the wavy line portion represents the bonding site with L.

[0142] As by R20 The alkyl group represented by is preferably an alkyl group having 1 to 30 carbon atoms, more preferably an alkyl group having 1 to 15 carbon atoms, and particularly preferably an alkyl group having 1 to 10 carbon atoms. The alkyl group may be linear or branched. The alkyl group may have a ring structure.

[0143] As R 20 The aryl group represented by is preferably an aryl group having 6 to 30 carbon atoms, more preferably an aryl group having 6 to 20 carbon atoms, and particularly preferably an aryl group having 6 to 12 carbon atoms. 20 An alkyl group is preferred.

[0144] From the perspective of decomposition and color rendering, R 20 The alkyl group represented by is preferably a secondary alkyl group or a tertiary alkyl group, more preferably a tertiary alkyl group. 20 The alkyl group represented by is preferably an alkyl group having 1 to 8 carbon atoms, more preferably a branched alkyl group having 3 to 10 carbon atoms, further preferably a branched alkyl group having 3 to 6 carbon atoms, particularly preferably isopropyl or tert-butyl, and most preferably tert-butyl.

[0145] Specific examples of the group represented by Formula 2 are shown below. However, the group represented by Formula 2 is not limited to the specific examples shown below. In the following structural formula, "●" represents a bonding site with L in Formula 1-1.

[0146] [Chemical Formula 10]

[0147]

[0148] In formula 3, R 30 represents an alkyl group or an aryl group, and the wavy line portion represents the bonding site with L. 30 The alkyl and aryl groups represented by R in formula 2 are respectively 20 The alkyl group and aryl group represented have the same meanings and preferred embodiments are also the same.

[0149] From the perspective of decomposition and color rendering, R 30 The alkyl group represented by is preferably a secondary alkyl group or a tertiary alkyl group, more preferably a tertiary alkyl group.30 The alkyl group represented by is preferably an alkyl group having 1 to 8 carbon atoms, more preferably a branched alkyl group having 3 to 10 carbon atoms, further preferably a branched alkyl group having 3 to 6 carbon atoms, particularly preferably an isopropyl group or a tert-butyl group, and most preferably a tert-butyl group. 30 The alkyl group represented by is preferably a substituted alkyl group, more preferably a fluorine-substituted alkyl group, further preferably a perfluoroalkyl group, and particularly preferably a trifluoromethyl group.

[0150] From the perspective of decomposition and color rendering, R 30 The aryl group represented by is preferably a substituted aryl group. Examples of the substituent in the substituted aryl group include an alkyl group (preferably an alkyl group having 1 to 4 carbon atoms) and an alkoxy group (preferably an alkoxy group having 1 to 4 carbon atoms).

[0151] Specific examples of the group represented by Formula 3 are shown below. However, the group represented by Formula 3 is not limited to the specific examples shown below. In the following structural formula, "●" represents a bonding site with L in Formula 1-1.

[0152] [Chemical Formula 11]

[0153]

[0154] In formula 4, R 41 and R 42 Each independently represents an alkyl group or an aryl group, Zb represents a counter ion for neutralizing the charge, and the wavy line portion represents a bonding site with L. 41 or R 42 The alkyl and aryl groups represented by R in formula 2 are respectively 20 The alkyl group and aryl group represented have the same meanings and preferred embodiments are also the same.

[0155] In formula 4, from the perspective of decomposition and color rendering, R 41 From the viewpoint of decomposability and color development, R 41 The alkyl group represented by is preferably an alkyl group having 1 to 8 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms, and particularly preferably a methyl group.

[0156] In formula 4, from the perspective of decomposition and color rendering, R 42 From the viewpoint of decomposability and color development, R 42 The alkyl group represented by is preferably a secondary alkyl group or a tertiary alkyl group, more preferably a tertiary alkyl group. 42The alkyl group represented by is preferably an alkyl group having 1 to 8 carbon atoms, more preferably a branched alkyl group having 3 to 10 carbon atoms, further preferably a branched alkyl group having 3 to 6 carbon atoms, particularly preferably isopropyl or tert-butyl, and most preferably tert-butyl.

[0157] In Formula 4, Zb may be any counter ion for neutralizing the charge, and may be included in Za in Formula 1-1 as the compound as a whole. Zb is preferably a sulfonate ion, a carboxylate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, a p-toluenesulfonate ion, or a perchlorate ion, and more preferably a tetrafluoroborate ion.

[0158] Specific examples of the group represented by Formula 4 are shown below. However, the group represented by Formula 4 is not limited to the specific examples shown below. In the following structural formula, "●" represents a bonding site with L in Formula 1-1.

[0159] [Chemical Formula 12]

[0160]

[0161] In formula 1-1, L is preferably an oxygen atom or -NR 10 -, more preferably an oxygen atom.

[0162] -NR 10 -R in 10 Preferably it is an alkyl group. 10 The alkyl group represented by is preferably an alkyl group having 1 to 10 carbon atoms. 10 The alkyl group represented by R may be linear or branched. 10 The alkyl group represented by may have a ring structure. The alkyl group is preferably a methyl group or a cyclohexyl group.

[0163] In-NR 10 - by R 10 The aryl group represented by is preferably an aryl group having 6 to 30 carbon atoms, more preferably an aryl group having 6 to 20 carbon atoms, and particularly preferably an aryl group having 6 to 12 carbon atoms. The aryl group may have a substituent.

[0164] In formula 1-1, R 11 ~R 18 Each independently represents a hydrogen atom, -R a 、-OR b 、-SR c or -NR d R e .

[0165] By R a ~R eThe hydrocarbon group represented by is preferably a hydrocarbon group having 1 to 30 carbon atoms, more preferably a hydrocarbon group having 1 to 15 carbon atoms, and particularly preferably a hydrocarbon group having 1 to 10 carbon atoms. The hydrocarbon group may be linear or branched. The hydrocarbon group may have a ring structure. The hydrocarbon group is preferably an alkyl group. The alkyl group is preferably an alkyl group having 1 to 30 carbon atoms, more preferably an alkyl group having 1 to 15 carbon atoms, and particularly preferably an alkyl group having 1 to 10 carbon atoms. The alkyl group may be linear or branched. The alkyl group may have a ring structure. Examples of the alkyl group include 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. Among the above, the alkyl group is preferably methyl, ethyl, propyl, or butyl. The alkyl group may have a substituent. Examples of the substituent include alkoxy, aryloxy, amino, alkylthio, arylthio, halogen, carboxyl, carboxylate, sulfo, sulfonate, alkoxycarbonyl, aryloxycarbonyl, and combinations thereof.

[0166] R in Formula 1-1 11 ~R 14 are each independently preferably a hydrogen atom or -R a (i.e., hydrocarbon group), more preferably a hydrogen atom or an alkyl group. 11 ~R 14 Each independently preferably represents a hydrogen atom.

[0167] In Formula 1-1, R bonded to the carbon atom bonded to the carbon atom to which L is bonded 11 and R 13 Preferably, an alkyl group is present, and more preferably, the two groups are linked to form a ring. The ring formed may be a monocyclic ring or a polycyclic ring. Examples of monocyclic rings include cyclopentene rings, cyclopentadiene rings, cyclohexene rings, and cyclohexadiene rings. Examples of polycyclic rings include indene rings and indole rings.

[0168] In Formula 1-1, R bonded to the carbon atom to which A1 is bonded 12 Optimum with R 15 or R 16 (Preferably R 16 ) are linked to form a ring. R bonded to the carbon atom to which A2 is bonded 14 Optimum with R 17 or R 18 (Preferably R 18 ) are connected to form a ring.

[0169] In formula 1-1, preferably n 13 is 1, R 16-R a (ie, a hydrocarbyl group).

[0170] In formula 1-1, R 16 Preferably, R is bonded to the carbon atom to which A1 is bonded. 12 The ring formed is preferably an indole ring, a pyrylium ring, a thiopyridinium ring, a benzoxazoline ring, or a benzimidazolinium ring. From the perspective of improving the visual recognition of the exposed portion, an indole ring is more preferred. These rings may further have a substituent.

[0171] In formula 1-1, preferably n 14 is 1, R 18 -R a (ie, a hydrocarbyl group).

[0172] In formula 1-1, R 18 Preferably, R is bonded to the carbon atom to which A2 is bonded. 14 The ring formed is preferably an indole ring, a pyran ring, a thiopyran ring, a benzoxazole ring or a benzimidazole ring, and is more preferably an indole ring from the perspective of improving the visual recognition of the exposed portion. These rings may further have a substituent.

[0173] R in Formula 1-1 16 and R 18 Preferably, they are the same groups. 16 and R 18 When forming a ring, it is preferred that the rings have the same structure except for A1 and A2.

[0174] R in Formula 1-1 15 and R 17 Preferably they are the same groups. 15 and R 17 Preferably -R a (ie, a hydrocarbon group), more preferably an alkyl group, and particularly preferably a substituted alkyl group.

[0175] From the viewpoint of improving the water solubility of the compound represented by Formula 1-1, R 15 and R 17 A substituted alkyl group is preferred. Examples of the substituted alkyl group include groups represented by the following formulae (a1) to (a4).

[0176] [Chemical Formula 13]

[0177]

[0178] -R W2 -CO2M (a2)

[0179] -R W3 -PO3M2 (a3)

[0180] -R W4 -SO3M (a4)

[0181] 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 from 1 to 45, R W1 represents an alkyl group having 1 to 12 carbon atoms or -C(=O)-R W5 , R W5 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 sodium atom, a potassium atom or an onium group.

[0182] In formula (a1), as R W0 Specific examples of the alkylene group represented by include ethylene, n-propylene, isopropylene, n-butylene, isobutylene, n-pentylene, isopentylene, n-hexyl and isohexyl, preferably ethylene, n-propylene, isopropylene or n-butylene, more preferably n-propylene.

[0183] In formula (a1), n W1 It is preferably 1-10, more preferably 1-5, and particularly preferably 1-3.

[0184] In formula (a1), as R W1 Specific examples of the alkyl group represented by include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl, n-hexyl, n-octyl and n-dodecyl, preferably methyl, ethyl, n-propyl, isopropyl, n-butyl or tert-butyl, more preferably methyl or ethyl, and particularly preferably methyl.

[0185] In formula (a1), R W5 The alkyl group represented by R W1 The alkyl groups represented have the same meanings and the preferred embodiments are also the same.

[0186] Specific examples of the group represented by formula (a1) are shown below. However, the group represented by formula (a1) is not limited to the specific examples shown below. In the following structural formula, Me represents a methyl group, Et represents an ethyl group, and * represents a bonding site.

[0187] [Chemical Formula 14]

[0188]

[0189] In formulas (a2) to (a4), as R W2 ~R W4Specific examples of the alkylene group represented by include methylene, ethylene, n-propylene, isopropylene, n-butylene, isobutylene, n-pentylene, isopentylene, n-hexyl, isohexylene, n-octylene and n-dodecylene, preferably ethylene, n-propylene, isopropylene or n-butylene, more preferably ethylene or n-propylene.

[0190] In formula (a3), two M's may be the same or different.

[0191] In formulae (a2) to (a4), examples of the onium group represented by M include an ammonium group, an iodonium group, a phosphonium group, and a sulfonium group.

[0192] CO2M in formula (a2), PO3M2 in formula (a2), and SO3M in formula (a4) may all have an anionic structure in which M is dissociated. The counter cation of the anionic structure may be A1 + , or R in formula 1-1 1 -L can contain a cation.

[0193] Among the groups represented by formula (a1) to formula (a4), the group represented by formula (a1), formula (a2) or formula (a4) is preferred.

[0194] n in formula 1-1 11 and n 12 They are preferably the same, and are preferably integers of 1 to 5, more preferably integers of 1 to 3, further preferably 1 or 2, and particularly preferably 2.

[0195] A1 and A2 in Formula 1-1 each independently represent an oxygen atom, a sulfur atom, or a nitrogen atom, preferably a nitrogen atom. A1 and A2 in Formula 1-1 are preferably the same atom.

[0196] In formula 1-1, Za represents a counter ion that neutralizes the charge. 11 ~R 18 and R 1 If all -L groups are neutral, Za becomes a monovalent counter anion. 11 ~R 18 and R 1 -L can have an anionic structure or a cationic structure. For example, in R 11 ~R 18 and R 1-L includes when two or more anionic structures, Za can also become counter cation. In addition, if the compound represented by formula 1-1 has an electrically neutral structure in the whole of the compound except Za, then Za is not required. In the case where Za is a counter anion, as a counter anion, for example, sulfonate ion, carboxylate ion, tetrafluoroborate ion, hexafluorophosphate ion, p-toluenesulfonate ion and perchlorate ion can be enumerated, preferably tetrafluoroborate ion. In the case where Za is a counter cation, as a counter cation, for example, alkali metal ion, alkaline earth metal ion, ammonium ion, pyridinium ion and sulfonium ion can be enumerated, preferably sodium ion, potassium ion, ammonium ion, pyridinium ion or sulfonium ion, more preferably sodium ion, potassium ion or ammonium ion.

[0197] (Compound represented by Formula 1-2)

[0198] The decomposable compound as one type of the color-changing compound is preferably a compound represented by the following formula 1-2. The compound represented by the following formula 1-2 is a cyanine pigment.

[0199] [Chemical Formula 15]

[0200]

[0201] In formula 1-2, R 1 represents a group represented by any one of the above formulae 2 to 4, R 19 ~R 22 Each independently represents a hydrogen atom, a halogen atom, -R a 、-OR b 、-CN、-SR c or -NR d R e , R 23 and R 24 Each independently represents -R a , R a ~R e Each independently represents a hydrocarbon group, R 19 With R 20 、R 21 With R 22 or R 23 With R 24 They can be linked to form a monocyclic or polycyclic ring, and L represents an oxygen atom, a sulfur atom or -NR 10 -, R 10 represents a hydrogen atom, an alkyl group or an aryl group, R d1 ~R d4 、W 1 and W 2 Each independently represents an alkyl group which may have a substituent, and Za represents a counter ion for neutralizing the charge.

[0202] R in Formula 1-2 1 and R in formula 1-1 1 The meaning is the same and the preferred method is also the same.

[0203] In formula 1-2, R 19 ~R 22 Each of the above is preferably independently a hydrogen atom, a halogen atom, -R a 、-OR b or -CN. R 19 and R 21 Preferably, it is a hydrogen atom or -R a . R 20 and R 22 Preferably, a hydrogen atom, -R a 、-OR b or -CN.

[0204] In formula 1-2, R 19 ~R 22 -R a Preferably, it is an alkyl group or an alkenyl group. 19 ~R 22 All -R a In the case of R 19 With R 20 and R 21 With R 22 are linked to form a monocyclic or polycyclic ring. 19 With R 20 or R 21 With R 22 Examples of the ring formed by linking include a benzene ring and a naphthalene ring.

[0205] In Formula 1-2, preferably R 23 With R 24 Linked to form a single ring or multiple rings. 23 With R 24 The ring formed by linking may be a monocyclic ring or a polycyclic ring. Examples of monocyclic rings include cyclopentene ring, cyclopentadiene ring, cyclohexene ring, and cyclohexadiene ring. Examples of polycyclic rings include indene ring.

[0206] In formula 1-2, R d1 ~R d4 Preferably, it is an unsubstituted alkyl group. d1 ~R d4 Examples of the unsubstituted alkyl group include unsubstituted alkyl groups having 1 to 4 carbon atoms, and a methyl group is preferred.

[0207] From the viewpoint of improving the water solubility of the compound represented by Formula 1-2, W in Formula 1-2 1 and W 2Each independently is preferably a substituted alkyl group. 1 and W 2 The substituted alkyl group represented by the formula (a1) to the formula (a4) described in the above "Compound represented by the formula 1-1" can be cited, and the preferred embodiment is the same. From the viewpoint of on-press development, W is preferred. 1 and W 2 Each independently represents an alkyl group having a substituent, and the substituent is a group in which at least -(OCH2CH2)-, a sulfo group, a salt of a sulfo group, a carboxyl group, or a salt of a carboxyl group.

[0208] In formula 1-2, Za represents a counter ion that neutralizes the charge in the molecule. 19 ~R 22 、R 23 ~R 24 、R d1 ~R d4 、W 1 、W 2 and R 1 If all -L groups are neutral, Za becomes a monovalent counter anion. 19 ~R 22 、R 23 ~R 24 、R d1 ~R d4 、W 1 、W 2 and R 1 -L can have an anionic structure or a cationic structure. For example, in R 19 ~R 22 、R 23 ~R 24 、R d1 ~R d4 、W 1 、W 2 and R 1 -L includes when 2 or more anionic structures, Za can also become counter cation. In addition, if the compound represented by formula 1-2 has an electrically neutral structure in the whole of the compound except Za, then Za is not required. The example when Za is a counter anion is the same as Za in formula 1-1, and the preferred embodiment is also the same. The example when Za is a counter cation is also the same as Za in formula 1-1, and the preferred embodiment is also the same.

[0209] (Compounds represented by Formula 1-3 to 1-7)

[0210] From the viewpoint of decomposability and color development, the decomposable compound as one type of color-changing compound is preferably a compound represented by any one of the following formulas 1-3 to 1-7, and more preferably a compound represented by any one of the following formulas 1-3, 1-5, and 1-6. The compounds represented by the following formulas 1-3 to 1-7 are cyanine pigments.

[0211] [Chemical Formula 16]

[0212]

[0213] In formulas 1-3 to 1-7, R 1 represents a group represented by any one of the above formulae 2 to 4, R 19 ~R 22 Each independently represents a hydrogen atom, a halogen atom, -R a 、-OR b 、-CN、-SR c or -NR d R e , R 23 and R 24 Each independently represents -R a , R 25 and R 26 Each independently represents a hydrogen atom, a halogen atom or -R a , R a ~R e Each independently represents a hydrocarbon group, R 19 With R 20 、R 21 With R 22 、R 23 With R 24 or R 25 With R 26 They can be linked to form a monocyclic or polycyclic ring, and L represents an oxygen atom, a sulfur atom or -NR 10 -, R 10 represents a hydrogen atom, an alkyl group or an aryl group, R d1 ~R d4 、W 1 and W 2 Each independently represents an alkyl group which may have a substituent, and Za represents a counter ion for neutralizing the charge.

[0214] R in Formulas 1-3 to 1-7 1 、R 19 ~R 22 、R d1 ~R d4 、W 1 、W 2 And L and R in formula 1-2 1 、R 19~R 22 、R d1 ~R d4 、W 1 、W 2 and L have the same meanings and the preferred embodiments are also the same. 25 and R 26 Each independently preferably is a hydrogen atom or an alkyl group, more preferably an alkyl group, and particularly preferably a methyl group.

[0215] Specific examples of the cyanine pigment contained in the degradable compound are shown below. However, the cyanine pigment is not limited to the specific examples shown below.

[0216] [Chemical Formula 17]

[0217]

[0218] As the cyanine pigment contained in the degradable compound, the infrared absorbing compound described in International Publication No. 2019 / 219560 can be preferably used.

[0219] The color-changing compound may include an acid developer. For example, the acid developers described in the "Image Recording Layer" section below can be used, and the preferred embodiments are the same. The color-changing compound may be a combination of the aforementioned decomposable compound and an acid generator described below.

[0220] The outermost layer may contain one color-changing compound alone or two or more color-changing compounds.

[0221] From the viewpoint of color development, the content of the color-changing compound in the outermost layer is preferably 0.10 to 50 mass %, more preferably 0.50 to 30 mass %, and particularly preferably 1.0 to 20 mass %, relative to the total mass of the outermost layer.

[0222] From the viewpoint of color development, the content of the color-changing compound in the outermost layer (M X ) and the content of the infrared absorber in the image recording layer (M Y ) ratio (M X / M Y ) is preferably 0.1 or more, more preferably 0.2 or more, and particularly preferably 0.3 or more and 3.0 or less.

[0223] [Other ingredients]

[0224] The outermost layer may contain components other than the above components as other components. Examples of other components include sensitizers, acid generators, and infrared absorbers.

[0225] The acid generator is a compound that generates acid by light or heat. As the acid generator, for example, a compound that decomposes and generates acid by infrared exposure can be cited. The acid generated is preferably a strong acid with a pKa of 2 or less (for example, sulfonic acid and hydrochloric acid). The acid developer can be discolored by the acid generated by the acid generator. From the viewpoint of sensitivity and stability, the acid generator is preferably an onium salt compound. Specific examples of onium salts preferred as acid generators include compounds described in paragraphs 0121 to 0124 of International Publication No. 2016 / 047392. Preferred are triarylsulfonium or diaryliodonium, sulfonates, carboxylates, BPh4 - 、BF4 - or PF6 - 、ClO4 - Here, Ph represents a phenyl group.

[0226] Examples of the infrared absorber include those described in the section "Image Recording Layer" below.

[0227] [Formation method]

[0228] The outermost layer can be formed by a known method (for example, coating method). The coating amount (solid content) of the outermost layer is preferably 5 mg / m 2 ~2,000 mg / m 2 , more preferably 20 mg / m 2 ~1,000 mg / m 2 In the present invention, "solid content" refers to components excluding the solvent.

[0229] <<Brightness Change>>

[0230] In one embodiment, at 110 mJ / cm 2 When the exposure is carried out based on infrared light with a wavelength of 830 nm at an energy density of , the brightness change ΔL before and after exposure is preferably 2.0 or more, more preferably 3.0 or more, further preferably 5.0 or more, particularly preferably 8.0 or more, and most preferably 10.0 or more. By having the brightness change ΔL within the above range, the visual recognition of the exposed part can be improved. There is no upper limit to the brightness change ΔL. As an example of the upper limit of the brightness change ΔL, 20.0 can be cited. In particular, when the outermost layer contains a color-changing compound, it is preferred that the brightness change ΔL satisfies the above range.

[0231] The lightness change ΔL was measured by the following method. A Luxel PLATES ETTER T-9800 manufactured by FUJIFILM Global Graphic Systems Co., Ltd., equipped with an infrared semiconductor laser having a wavelength of 830 nm, was used under conditions of 99.5% output, 220 rpm (revolutions per minute) for the external drum, and 2,400 dpi (dots per inch, 1 inch = 25.4 mm) for the resolution (energy density: 110 mJ / cm 2 ) was used to expose the lithographic printing plate precursor. The exposure was carried out at 25°C and 50% RH (relative humidity). The change in lightness of the lithographic printing plate precursor before and after exposure was measured. The lightness was measured using a spectrocolorimeter exact manufactured by x-Rite Inc. Specifically, L was measured from the outermost side of the lithographic printing plate precursor. * a * b * L in color system * Value (brightness), the exposure part of the L * The L value of the unexposed part * The absolute value of the difference between the two values ​​is taken as the brightness change ΔL.

[0232] <<Support>>

[0233] The on-press development type lithographic printing plate precursor according to one embodiment of the present invention comprises a support. As the support, it is possible to appropriately select and use from among the supports used in known lithographic printing plate precursors. As the support, a support having a hydrophilic surface is preferably used.

[0234] The support is preferably an aluminum plate that has been roughened and anodized by a known method. Specifically, the support preferably comprises an aluminum plate and an aluminum anodic oxide film disposed on the aluminum plate.

[0235] The aluminum anodic oxide film is preferably located closer to the image recording layer than the aluminum plate. The aluminum anodic oxide film preferably has micropores extending in the depth direction from the surface on the image recording layer side.

[0236] Hereinafter, preferred embodiments of the support body will be described with reference to the drawings. Figure 1 This is a schematic cross-sectional view of a support body according to one embodiment. Figure 1The aluminum support 12a shown has a structure in which an aluminum plate 18 and an aluminum anodic oxide film 20a (hereinafter also referred to as "anodic oxide film 20a") are laminated in this order. The anodic oxide film 20a in the aluminum support 12a is located closer to the image recording layer than the aluminum plate 18. In other words, the lithographic printing plate precursor according to one embodiment preferably comprises an aluminum plate and has at least an aluminum anodic oxide film, an image recording layer, and an outermost layer in this order on the aluminum plate.

[0237] The following describes a preferred embodiment of the anodic oxide film 20a. The anodic oxide film 20a is formed on the surface of the aluminum plate 18 by anodizing. The anodic oxide film 20a has ultrafine micropores 22a that are substantially perpendicular to the film surface and are uniformly distributed. The micropores 22a extend from the surface of the anodic oxide film 20a on the image recording layer side (i.e., the surface of the anodic oxide film 20a opposite the aluminum plate 18 side) in the depth direction (i.e., toward the aluminum plate 18 side).

[0238] The average diameter of the micropores 22a at the surface of the anodic oxide film 20a (i.e., the average opening diameter) exceeds 10 nm and is less than 100 nm. If the average diameter of the micropores 22a at the surface of the anodic oxide film 20a exceeds 10 nm, the printing durability and image visual recognition are improved. If the average diameter of the micropores 22a at the surface of the anodic oxide film 20a is less than 100 nm, the printing durability is improved. From the perspective of the balance between printing durability, contamination resistance and image visual recognition, the average diameter of the micropores 22a at the surface of the anodic oxide film 20a is preferably 15 nm to 60 nm, more preferably 20 nm to 50 nm, and particularly preferably 25 nm to 40 nm. The diameter inside the micropore 22a can be wider or narrower than the opening diameter of the micropore 22a. The average diameter of the micropores 22a at the surface of the anodic oxide film 20a is the value obtained by measuring the diameters of 50 micropores within a range of 400 nm × 600 nm in four images obtained by observing four locations on the surface of the anodic oxide film 20a using a field emission scanning electron microscope (FE-SEM) at a magnification of 150,000 times, and averaging the obtained measured values. In addition, when the shape of the observed micropores 22a is not circular, the circle equivalent diameter is used. The "circle equivalent diameter" refers to the diameter of a circle when the shape of the opening is assumed to be a circle having the same projected area as the projected area of ​​the opening.

[0239] The shape of the micropores 22a in the depth direction is not limited. Figure 1The micropore 22a shown is generally straight (generally cylindrical). The micropore 22a may be conical in shape, with the diameter decreasing in depth (thickness direction). The shape of the bottom of the micropore 22a is not limited. The bottom of the micropore 22a may be curved (convex) or flat.

[0240] The micropores in the support may have 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 predetermined depth, and the small-diameter pore portion communicates with the bottom of the large-diameter pore portion and extends from the communication point with the large-diameter pore portion to a predetermined depth. The terms "large diameter" used for the large-diameter pore portion and "small diameter" used for the small-diameter pore portion refer to the relative size relationship with respect to the pore diameter. In other words, the diameter of the large-diameter pore portion only needs to be larger than the diameter of the small-diameter pore portion.

[0241] Figure 2 is a schematic cross-sectional view of a support body according to another embodiment. Figure 2 As shown, the aluminum support 12b includes an aluminum plate 18 and an anodic oxide film 20b, which has micropores 22b having large-diameter pores 24 and small-diameter pores 26. For example, the micropores 22b in the anodic oxide film 20b include the large-diameter pores 24 and the small-diameter pores 26, wherein the large-diameter pores 24 extend from the surface of the anodic oxide film 20b to a depth of 10 nm to 1,000 nm (i.e., Figure 2 The small-diameter hole portion 26 is connected to the bottom of the large-diameter hole portion 24 at a depth D shown in FIG. The small-diameter hole portion 26 further extends from the connection point with the large-diameter hole portion 24 to a depth of 20 nm to 2,000 nm. Specific embodiments of the large-diameter and small-diameter hole portions can be employed, for example, as described in paragraphs 0107 to 0114 of Japanese Patent Application Laid-Open No. 2019-162855.

[0242] In one embodiment, the support preferably comprises an aluminum plate and an anodic oxide film of aluminum disposed on the aluminum plate, the anodic oxide film being located closer to the image recording layer than the aluminum plate, the anodic oxide film having micropores extending in the depth direction from the surface on the image recording layer side, the average diameter of the micropores at the surface of the anodic oxide film exceeding 10 nm and being 100 nm or less. Furthermore, the micropores preferably comprise a large-diameter pore portion and a small-diameter pore portion, the large-diameter pore portion extending from the surface of the anodic oxide film to a depth of 10 nm to 1,000 nm, the small-diameter pore portion communicating with the bottom of the large-diameter pore portion and extending from the communication position with the large-diameter pore portion to a depth of 20 nm to 2,000 nm, the average diameter of the large-diameter pore portion at the surface of the anodic oxide film being 15 nm to 100 nm, and the average diameter of the small-diameter pore portion at the communication position being 13 nm or less.

[0243] [Method for Manufacturing Support Body]

[0244] As a method for producing the support, for example, a method of performing the following steps in sequence is preferable.

[0245] (1) Roughening process: A process for roughening the aluminum plate

[0246] (2) Anodizing process: Anodizing the roughened aluminum plate

[0247] (3) Pore enlargement step: The aluminum plate having an anodic oxide film obtained in the anodic oxidation step is brought into contact with an acid aqueous solution or an alkali aqueous solution to enlarge the diameter of the micropores in the anodic oxide film.

[0248] Hereinafter, the steps of each process will be described in detail.

[0249] (Roughening process)

[0250] The roughening treatment step is performed, for example, by subjecting the surface of the aluminum plate to a roughening treatment including an electrochemical roughening treatment. The roughening treatment step is preferably performed before the anodizing treatment step described below. However, if the surface of the aluminum plate already has a preferred surface shape, this step is not necessary. The roughening treatment step can be performed, for example, by the method described in paragraphs 0086 to 0101 of Japanese Patent Application Laid-Open No. 2019-162855.

[0251] (Anodizing process)

[0252] There are no particular restrictions on the steps of the anodizing process as long as the above-mentioned micropores can be obtained, and a known method can be used. In the anodizing process, for example, an aqueous solution of sulfuric acid, phosphoric acid or oxalic acid can be used as an electrolyte. For example, as the concentration of sulfuric acid, 100 g / L to 300 g / L can be cited. The conditions for the anodizing treatment can be appropriately set according to the electrolyte used. For example, as a liquid temperature of 5°C to 70°C (preferably 10°C to 60°C), as a current density of 0.5 A / dm 2 ~60A / dm 2 (Preferably 1A / dm 2 ~60A / dm 2 ), as voltage is 1V to 100V (preferably 5V to 50V), as electrolysis time is 1 second to 100 seconds (preferably 5 seconds to 60 seconds) and as film amount is 0.1g / m 2 ~5g / m 2 (Preferably 0.2 g / m 2 ~3g / m 2 ) conditions.

[0253] (Hole expansion process)

[0254] The pore enlargement process is a process for enlarging the diameter of the micropores present in the anodic oxide film formed by the above-mentioned anodizing process. The pore enlargement process can be carried out by contacting the aluminum plate obtained by the above-mentioned anodizing process with an acid aqueous solution or an alkaline aqueous solution. There are no particular restrictions on the contact method, and examples include immersion and spraying.

[0255] <<Image Recording Layer>>

[0256] An on-press developable lithographic printing plate precursor according to one embodiment of the present invention comprises an image-recording layer. The image-recording layer is preferably a negative-tone image-recording layer. The image-recording layer preferably comprises a polymerization initiator and a polymerizable compound, and more preferably comprises an infrared absorber, a polymerization initiator, and a polymerizable compound.

[0257] [Infrared absorber]

[0258] The image recording layer preferably contains an infrared absorber. Examples of the infrared absorber include pigments and dyes.

[0259] Examples of dyes that can be used as infrared absorbers include commercially available dyes and known dyes (e.g., dyes described in "Dye Handbook" (Edited by The Society of Synthetic Organic Chemistry, Japan, published in 1977). Specific examples of dyes include azo dyes, metal complex salt azo dyes, pyrazolone azo dyes, naphthoquinone dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinoneimine dyes, methine dyes, cyanine pigments, squarylium pigments, pyrylium salts, and metal thiol complexes.

[0260] As preferred dyes, for example, cyanine pigments, squaric acid pigments, pyrylium salts, nickel thiol complexes and indocyanine pigments can be enumerated. As more preferred dyes, cyanine pigments and indocyanine pigments can be enumerated. Among the above, cyanine pigments are particularly preferred.

[0261] The infrared absorber is preferably a cationic polymethine dye having an oxygen atom, a nitrogen atom or a halogen atom at the meta position. Preferred cationic polymethine dyes include, for example, cyanine dyes, pyrylium dyes, thiopyridinium dyes and azulene dyes. From the viewpoint of ease of acquisition and solvent solubility during the introduction reaction, the cationic polymethine dye is preferably a cyanine dye.

[0262] Specific examples of cyanine pigments include compounds described in paragraphs 0017 to 0019 of Japanese Patent Application Laid-Open No. 2001-133969, compounds described in paragraphs 0016 to 0021 of Japanese Patent Application Laid-Open No. 2002-023360, and compounds described in paragraphs 0012 to 0037 of Japanese Patent Application Laid-Open No. 2002-040638. Preferred cyanine pigments include, for example, compounds described in paragraphs 0034 to 0041 of Japanese Patent Application Laid-Open No. 2002-278057 and compounds described in paragraphs 0080 to 0086 of Japanese Patent Application Laid-Open No. 2008-195018. Particularly preferred anthocyanine pigments include, for example, compounds described in paragraphs 0035 to 0043 of JP-A-2007-90850 and compounds described in paragraphs 0105 to 0113 of JP-A-2012-206495. Compounds described in paragraphs 0008 to 0009 of JP-A-5-5005 and paragraphs 0022 to 0025 of JP-A-2001-222101 can also be preferably used.

[0263] As the counter cation of the cyanine dye, for example, a borate compound described later can be used.

[0264] As the pigment, the compounds described in paragraphs 0072 to 0076 of JP-A-2008-195018 are preferred.

[0265] As the infrared absorber, an infrared absorber that decomposes by infrared exposure (hereinafter also referred to as a "decomposable infrared absorber") can be preferably used. As the infrared absorber that decomposes by infrared exposure, the compounds described in JP-A-2008-544322, WO-2016 / 027886, WO-2017 / 141882, or WO-2018 / 043259 can be preferably used.

[0266] The image recording layer may contain one infrared ray absorber alone or two or more infrared ray absorbers. In addition, a pigment and a dye may be used in combination as the infrared ray absorber.

[0267] The content of the infrared absorber is preferably 0.1% by mass to 10.0% by mass, more preferably 0.5% by mass to 5.0% by mass, relative to the total mass of the image recording layer.

[0268] [Polymerization initiator]

[0269] The image recording layer preferably contains a polymerization initiator. Examples of the polymerization initiator include electron-accepting polymerization initiators and electron-donating polymerization initiators. The image recording layer preferably contains an electron-accepting polymerization initiator, more preferably contains at least one selected from an electron-accepting polymerization initiator and an electron-donating polymerization initiator, and particularly preferably contains an electron-accepting polymerization initiator and an electron-donating polymerization initiator.

[0270] (Electron-accepting polymerization initiator)

[0271] The image recording layer preferably contains an electron-accepting polymerization initiator. The electron-accepting polymerization initiator is a compound that generates a polymerization initiating species (eg, a radical) by accepting an electron through intermolecular electron transfer when electrons of an infrared absorber are excited by infrared exposure.

[0272] Examples of electron-accepting polymerization initiators include compounds that generate polymerization initiating species (e.g., free radicals or cations) by the energy of light, heat, or both (e.g., thermal polymerization initiators, compounds having bonds with low bond dissociation energy, and photopolymerization initiators). Electron-accepting polymerization initiators are preferably free radical polymerization initiators, and more preferably onium salt compounds. Furthermore, electron-accepting polymerization initiators are preferably infrared-sensitive polymerization initiators.

[0273] Preferred electron-accepting polymerization initiators include oxime ester compounds and onium salt compounds from the perspective of curability. From the perspective of 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 particularly preferred.

[0274] The iodonium salt compound is preferably a diaryliodonium salt compound, and more preferably a diphenyliodonium salt compound substituted with an electron-donating group such as an alkyl group or an alkoxy group. Furthermore, the iodonium salt compound is preferably an asymmetric diphenyliodonium salt compound. Specific examples of the iodonium salt compound include diphenyliodonium hexafluorophosphate, 4-methoxyphenyl-4-(2-methylpropyl)phenyliodonium hexafluorophosphate, 4-(2-methylpropyl)phenyl-p-tolyliodonium hexafluorophosphate, 4-hexyloxyphenyl-2,4,6-trimethoxyphenyliodonium hexafluorophosphate, 4-hexyloxyphenyl-2,4-diethoxyphenyliodonium tetrafluoroborate, 4-octyloxyphenyl-2,4,6-trimethoxyphenyliodonium 1-perfluorobutanesulfonate, 4-octyloxyphenyl-2,4,6-trimethoxyphenyliodonium hexafluorophosphate, and bis(4-tert-butylphenyl)iodonium tetraphenylborate.

[0275] As examples of counter anions of iodonium salt compounds or sulfonium salt compounds, sulfonate anions, carboxylate anions, tetrafluoroborate anions, hexafluorophosphate anions, p-toluenesulfonate anions, p-toluenesulfonate anions, sulfonamide anions or sulfonimide anions can be cited. Among the above, sulfonamide anions or sulfonimide anions are preferred, and sulfonimide anions are more preferred. As sulfonamide anions, arylsulfonamide anions are preferred. And, as sulfonimide anions, bisarylsulfonimide anions are preferred. As specific examples of sulfonamide anions or sulfonimide anions, compounds described in paragraph 0034 of International Publication No. 2019 / 013268 can be cited. The contents of the above-mentioned publications are incorporated into this specification by reference.

[0276] From the perspective of color development and developability over time after exposure, and the UV printing durability of the resulting lithographic printing plate, the electron-accepting polymerization initiator is preferably at least one selected from the group consisting of a compound represented by the following formula (II) and a compound represented by the following formula (III), and more preferably a compound represented by the following formula (II). Furthermore, compounds represented by the following formula (II) and compounds represented by the following formula (III) are preferred due to their excellent visual recognition.

[0277] [Chemical Formula 18]

[0278]

[0279] In formula (II) and formula (III), X represents a halogen atom, R 3 、R 4 and R 5 Each independently represents a monovalent hydrocarbon group. The number of carbon atoms in the hydrocarbon group is preferably 1 to 20. In formula (II), X preferably represents a halogen atom, and R 3 Represents an aryl group.

[0280] Examples of X in formula (II) and formula (III) include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. X in formula (II) and formula (III) is preferably a bromine atom.

[0281] In formula (U) and formula (III), R 3 、R 4 and R 5 Each of the groups is independently preferably an aryl group, and from the viewpoint of excellent balance between sensitivity and storage stability, an aryl group substituted with an amide group is more preferable.

[0282] The electron-accepting polymerization initiator is particularly preferably a compound represented by the following formula (IV).

[0283] [Chemical Formula 19]

[0284]

[0285] In formula (IV), X represents a halogen atom, R 4 and R 5 Each independently represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms, p and q each independently represent an integer of 1 to 5, and p+q is an integer of 2 to 6. X in formula (IV) has the same meaning as X in formula (II).

[0286] Specific examples of the compound represented by formula (II) are shown below. However, the compound represented by formula (II) is not limited to the specific examples shown below.

[0287] [Chemical Formula 20]

[0288]

[0289] [Chemical Formula 21]

[0290]

[0291] [Chemical Formula 22]

[0292]

[0293] [Chemical Formula 23]

[0294]

[0295] [Chemical Formula 24]

[0296]

[0297] [Chemical Formula 25]

[0298]

[0299] [Chemical Formula 26]

[0300]

[0301] From the perspective of improving sensitivity and preventing plate wear, the lowest unoccupied molecular orbital (LUMO) energy level of the electron-accepting polymerization initiator is preferably -3.00 eV or less, more preferably -3.02 eV or less. The lowest unoccupied molecular orbital (LUMO) energy level of the electron-accepting polymerization initiator is preferably -3.80 eV or greater, more preferably -3.50 eV or greater.

[0302] In the present invention, the energy levels of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) were calculated using the following method. First, the counter anions in the compound being calculated were ignored. Structural optimization was performed using the quantum chemical calculation software Gaussian 09 using DFT (B3LYP / 6-31G(d)). MO (molecular orbital) energy calculations were performed using DFT (B3LYP / 6-31+G(d,p) / CPCM (solvent = methanol)) based on the structure obtained through the above-mentioned structural optimization. The MO energy Ebare (unit: Hartree) obtained through the MO energy calculation was converted to Escaled (unit: eV), which is used as the HOMO and LUMO values ​​in the present invention, according to the following formula. In the following formula, 27.2114 is a coefficient used only for Hartree conversion to eV, and 0.823168 and -1.07634 are adjustment coefficients used to determine the HOMO and LUMO of the compound being calculated so that the calculated values ​​match the measured values.

[0303] Formula: Escaled=0.823168×27.2114×Ebare-1.07634

[0304] The image recording layer may contain one kind alone or two or more kinds of electron-accepting polymerization initiators.

[0305] The content of the electron-accepting polymerization initiator relative to the total mass of the image recording layer is preferably 0.1 to 50 mass%, more preferably 0.5 to 30 mass%, and particularly preferably 0.8 to 20 mass%.

[0306] (Electron-donating polymerization initiator)

[0307] The image recording layer preferably contains an electron-donating polymerization initiator. This is a compound that, when exposed to infrared light and electrons in the infrared absorber are excited or migrate within the molecule, donates an electron to an orbital from which an electron in the infrared absorber has been released, through intermolecular electron migration, thereby generating a polymerization initiating species (e.g., a free radical). The electron-donating polymerization initiator is preferably an electron-donating free radical polymerization initiator.

[0308] From the perspective of printing durability, the image recording layer preferably contains a borate compound as an electron-donating polymerization initiator. From the perspective of printing durability and color development, the borate compound is preferably a tetraaryl borate compound or a monoalkyltriaryl borate compound, and more preferably a tetraaryl borate compound.

[0309] The counter cation of the borate compound is not limited. The counter cation of the borate compound is preferably an alkali metal ion or a tetraalkylammonium ion, more preferably a sodium ion, a potassium ion, or a tetrabutylammonium ion. Furthermore, the counter cation of the borate compound may be the cationic polymethine dye described above under "Infrared Absorber."

[0310] As a preferable borate compound, sodium tetraphenylborate is mentioned, for example.

[0311] Preferred specific examples of electron-donating polymerization initiators (B-1 to B-9) are shown below. In the following chemical formula, Ph represents a phenyl group and Bu represents an n-butyl group. However, the electron-donating polymerization initiator is not limited to the specific examples shown below.

[0312] [Chemical Formula 27]

[0313]

[0314] From the perspective of improving sensitivity and reducing plate wear, the energy level of the highest occupied molecular orbital (HOMO) of the electron-donating polymerization initiator is preferably -6.00 eV or higher, more preferably -5.95 eV or higher, and particularly preferably -5.93 eV or higher. The energy level of the highest occupied molecular orbital (HOMO) of the electron-donating polymerization initiator is preferably -5.00 eV or lower, more preferably -5.40 eV or lower.

[0315] The image recording layer may contain one kind alone or two or more kinds of electron-donating polymerization initiators.

[0316] From the viewpoint of sensitivity and printing durability, the content of the electron donating polymerization initiator relative to the total mass of the image recording layer is preferably 0.01 to 30 mass %, more preferably 0.05 to 25 mass %, and particularly preferably 0.1 to 20 mass %.

[0317] (Compound formed by an electron-donating polymerization initiator and an electron-accepting polymerization initiator forming an ion pair)

[0318] In one embodiment, the image recording layer preferably includes an electron-donating polymerization initiator and an electron-accepting polymerization initiator to form an ion pair (i.e., a salt). For example, the polymerization initiator is preferably a compound formed by an anion in the electron-donating polymerization initiator and a cation in the electron-accepting polymerization initiator to form an ion pair, more preferably a compound formed by an onium cation and a borate anion to form an ion pair, further preferably a compound formed by an iodonium cation or a sulfonium cation and a borate anion to form an ion pair, and especially preferably a compound formed by a diaryl iodonium cation or a triaryl sulfonium cation and a tetraaryl borate anion to form an ion pair. The preferred mode of the anion in the electron-donating polymerization initiator forming an ion pair is the same as the preferred mode of the anion in the electron-donating polymerization initiator described above. The preferred mode of the cation in the electron-accepting polymerization initiator forming an ion pair is the same as the preferred mode of the cation in the electron-accepting polymerization initiator described above.

[0319] When the image recording layer contains an anion as an electron-donating polymerization initiator and a cation as an electron-accepting polymerization initiator (i.e., when the image recording layer contains a compound that forms an ion pair as described above), the image recording layer contains an electron-accepting polymerization initiator and an electron-donating polymerization initiator. The compound that forms an ion pair with the electron-donating polymerization initiator and the electron-accepting polymerization initiator can be used as an electron-donating polymerization initiator or as an electron-accepting polymerization initiator. The compound that forms an ion pair with the electron-donating polymerization initiator and the electron-accepting polymerization initiator can be used in combination with the electron-donating polymerization initiator described above or with the electron-accepting polymerization initiator described above.

[0320] (Polymerization initiator content)

[0321] The image recording layer may contain one or more polymerization initiators. The content of the polymerization initiator is preferably 0.1% to 50% by mass, more preferably 0.5% to 30% by mass, and particularly preferably 0.8% to 20% by mass, relative to the total mass of the image recording layer.

[0322] (Preferred Embodiments of Electron Donating Polymerization Initiator and Infrared Absorber)

[0323] In the image recording layer, from the perspective of improving sensitivity and printing durability, the value of the highest occupied molecular orbital (HOMO) energy level of the infrared absorber minus the highest occupied molecular orbital (HOMO) energy level of the electron donating polymerization initiator is preferably 0.70 eV or less, more preferably 0.70 eV to -0.10 eV. A negative value means that the HOMO energy level of the electron donating polymerization initiator is higher than the HOMO energy level of the infrared absorber.

[0324] (Preferred Embodiments of Electron-Accepting Polymerization Initiator and Infrared Absorber)

[0325] In the image recording layer, from the perspective of improving sensitivity and printing durability, the value of the energy level of the lowest unoccupied molecular orbital (LUMO) of the electron-accepting polymerization initiator minus the energy level of the lowest unoccupied molecular orbital (LUMO) of the infrared absorber is preferably 1.00 eV or less, more preferably 1.00 eV to -0.10 eV, and particularly preferably 0.80 eV to 0.30 eV. A negative value indicates that the LUMO energy level of the infrared absorber is higher than the LUMO energy level of the electron-accepting polymerization initiator.

[0326] [Polymerizable compound]

[0327] The image recording layer preferably contains a polymerizable compound. In the present invention, the "polymerizable compound" refers to a compound having a polymerizable group.

[0328] As the polymerizable group, for example, known polymerizable groups can be mentioned. The polymerizable group is preferably an ethylenically unsaturated group. In addition, the polymerizable group can be a free radical polymerizable group or a cationic polymerizable group, preferably a free radical polymerizable group. As the free radical polymerizable group, for example, (meth)acryloyl, allyl, vinylphenyl and vinyl can be mentioned. From the viewpoint of reactivity, (meth)acryloyl is preferred.

[0329] The molecular weight (weight average molecular weight when there is a molecular weight distribution) of the polymerizable compound is preferably 50 or more and less than 2,500.

[0330] The polymerizable compound may be, for example, a free radical polymerizable compound or a cationically polymerizable compound, and is preferably an addition polymerizable compound having at least one ethylenically unsaturated bond (i.e., an ethylenically unsaturated compound). The ethylenically unsaturated compound is preferably a compound having at least one terminal ethylenically unsaturated bond, and more preferably a compound having two or more terminal ethylenically unsaturated bonds.

[0331] The chemical form of the polymerizable compound may be a monomer, a prepolymer (eg, a dimer, a trimer, or an oligomer), or a mixture thereof.

[0332] From the perspective of UV printing durability, the polymerizable compound preferably has 3 or more polymerizable groups, more preferably 7 or more polymerizable groups, and particularly preferably 10 or more polymerizable groups. From the perspective of UV printing durability of the resulting lithographic printing plate, the polymerizable compound preferably comprises an ethylenically unsaturated compound having 3 or more (preferably 7 or more, more preferably 10 or more) ethylenically unsaturated groups, and more preferably comprises a (meth)acrylate compound having 3 or more (preferably 7 or more, more preferably 10 or more) (meth)acryloyl groups.

[0333] (Oligomer)

[0334] The polymerizable compound preferably includes a polymerizable compound that is an oligomer (hereinafter also referred to as an "oligomer"). In the present invention, an "oligomer" refers to a polymerizable compound having a molecular weight (weight average molecular weight when a molecular weight distribution exists) of 600 to 10,000 inclusive and having at least one polymerizable group. From the perspective of excellent chemical resistance and UV printing durability, the molecular weight of the oligomer is preferably 1,000 to 5,000 inclusive.

[0335] From the perspective of improving UV printing durability, the number of polymerizable groups in one oligomer molecule is preferably 2 or more, more preferably 3 or more, further preferably 6 or more, and particularly preferably 10 or more. There is no upper limit on the number of polymerizable groups in the oligomer. The number of polymerizable groups in the oligomer is preferably 20 or less.

[0336] From the perspectives of UV printing durability and on-press developability, the oligomer preferably has 7 or more polymerizable groups and a molecular weight of 1,000 to 10,000, and more preferably has 7 or more polymerizable groups and 20 or less polymerizable groups and a molecular weight of 1,000 to 5,000. Furthermore, when the image-recording layer contains an oligomer as a polymerizable compound, the image-recording layer may contain a polymer component that may be produced during the production of the oligomer.

[0337] From the viewpoint of UV printing durability, visual recognition and on-press developability, the oligomer preferably contains at least one selected from a compound having a carbamate bond, a compound having an ester bond and a compound having an epoxy residue, and more preferably contains a compound having a carbamate bond. In the present invention, "epoxy residue" refers to a group having a structure formed by an epoxy group. As an example of a structure formed by an epoxy group, a structure obtained by the reaction of an acid group (e.g., a carboxylic acid group) and an epoxy group can be cited.

[0338] -Compounds having a urethane bond-

[0339] The compound having a urethane bond as an example of an oligomer is preferably a compound having at least a group represented by the following formula (Ac-1) or formula (Ac-2), and more preferably a compound having at least a group represented by the following formula (Ac-1).

[0340] [Chemical Formula 28]

[0341]

[0342] 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 indicates a bonding position to other structures.

[0343] L in formula (Ac-1) and formula (Ac-2) 1 ~L 4 Each independently preferably is an alkylene group having 2 to 20 carbon atoms, more preferably an alkylene group having 2 to 10 carbon atoms, and particularly preferably an alkylene group having 4 to 8 carbon atoms. The alkylene group may have a branched structure or a cyclic structure. The alkylene group is preferably a straight-chain alkylene group.

[0344] It is preferred that the wavy line portion in formula (Ac-1) or formula (Ac-2) is independently directly bonded to the wavy line portion in the group represented by the following formula (Ae-1) or formula (Ae-2).

[0345] [Chemical Formula 29]

[0346]

[0347] In formula (Ae-1) and formula (Ae-2), R each independently represents an acryloyloxy group or a methacryloyloxy group, and the wavy portion represents a bonding position to the wavy portion in formula (Ac-1) or formula (Ac-2).

[0348] As the compound having a urethane bond, a compound obtained by introducing a polymerizable group into a polyurethane obtained by reacting a polyisocyanate compound with a polyol compound through a polymer reaction 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 obtained by reacting a polyol compound having an acid group with a polyisocyanate compound.

[0349] -Compounds having ester bonds-

[0350] The number of polymerizable groups in the compound having an ester bond, which is an example of an oligomer, is preferably 3 or more, more preferably 6 or more.

[0351] -Compounds having epoxy residues-

[0352] As an example of an oligomer, a compound having an epoxy residue preferably contains a hydroxyl group. The number of polymerizable groups in the compound having an epoxy residue is preferably 2 to 6, more preferably 2 to 3. Compounds having an epoxy residue can be obtained, for example, by reacting acrylic acid with a compound having an epoxy group.

[0353] As the oligomer, commercially available products can be used. Examples of commercially available products include UA-510H, UA-306H, UA-306I, and UA-306T (all manufactured by KYOEISHA CHEMICAL CO., LTD.), UV-1700B, UV-6300B, and UV7620EA (all manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), U-15HA (manufactured by Shin-Nakamura Chemical Co., Ltd.), and EBECRYL 450, EBECRYL 657, EBECRYL 885, EBECRYL 800, EBECRYL 3416, and EBECRY L860 (all manufactured by DAICEL-ALLNEX LTD.). However, commercially available oligomers are not limited to the above-mentioned commercial products.

[0354] From the viewpoint of improving chemical resistance, UV printing durability, and suppression of on-press development residue, the content of the oligomer is preferably 30% by mass to 100% by mass, more preferably 50% by mass to 100% by mass, and particularly preferably 80% by mass to 100% by mass, relative to the total mass of the polymerizable compound in the image recording layer.

[0355] (Low molecular weight polymerizable compound)

[0356] The polymerizable compound may also include polymerizable compounds other than oligomers. From the perspective of chemical resistance, polymerizable compounds other than oligomers are preferably low molecular weight polymerizable compounds. The chemical form of the low molecular weight polymerizable compound may be a monomer, dimer, trimer, or a mixture thereof. From the perspective of chemical resistance, the low molecular weight polymerizable compound is preferably at least one selected from a polymerizable compound having three or more ethylenically unsaturated groups and a polymerizable compound having an isocyanurate ring structure.

[0357] In the present invention, the "low-molecular-weight polymerizable compound" refers to a polymerizable compound having a molecular weight (weight-average molecular weight when having a molecular weight distribution) of 50 or more and less than 600. From the viewpoint of excellent chemical resistance, UV printing durability, and suppression of on-press development residue, the molecular weight of the low-molecular-weight polymerizable compound is preferably 100 or more and less than 600, more preferably 300 or more and less than 600, and particularly preferably 400 or more and less than 600.

[0358] When the polymerizable compound contains a low-molecular-weight polymerizable compound as a polymerizable compound other than the oligomer, the ratio of the content of the oligomer (the total amount when the polymerizable compound contains two or more oligomers) to the content of the low-molecular-weight polymerizable compound (the total amount when the polymerizable compound contains two or more low-molecular-weight polymerizable compounds) (i.e., oligomer / low-molecular-weight polymerizable compound) is preferably 10 / 1 to 1 / 10 on a mass basis, more preferably 10 / 1 to 3 / 7, and particularly preferably 10 / 1 to 7 / 3, from the viewpoints of chemical resistance, UV printing durability, and suppression of on-press development residue.

[0359] As the polymerizable compound, the polymerizable compounds described in paragraphs 0082 to 0086 of International Publication No. 2019 / 013268 can be used. The contents of the above publication are incorporated into this specification by reference.

[0360] The image recording layer may contain one kind of polymerizable compound alone or two or more kinds of polymerizable compounds. From the viewpoint of UV printing durability, the image recording layer preferably contains two or more kinds of polymerizable compounds.

[0361] The content of the polymerizable compound relative to the total mass of the image recording layer (when the image recording layer contains two or more polymerizable compounds, 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 particularly preferably 15% by mass to 60% by mass.

[0362] [particle]

[0363] From the viewpoint of developability and UV printing durability, the image recording layer preferably contains particles. The particles may be inorganic particles or organic particles. The image recording layer preferably contains organic particles as particles, more preferably resin particles. As the inorganic particles, for example, known inorganic particles can be used. As the inorganic particles, metal oxide particles (for example, silicon dioxide particles or titanium dioxide particles) can be preferably used.

[0364] (resin particles)

[0365] Examples of the resin particles include particles containing an addition polymerization type resin (i.e., addition polymerization type resin particles), particles containing an addition polymerization type resin (i.e., addition polymerization type resin particles), and particles containing a condensation type resin (i.e., condensation polymerization type resin particles). The resin particles are preferably addition polymerization type resin particles or addition polymerization type resin particles. From the perspective of enabling thermal fusion, the resin particles may be particles containing a thermoplastic resin (i.e., thermoplastic resin particles).

[0366] The resin particles may be in the form of, for example, microcapsules or microgels (ie, cross-linked resin particles).

[0367] The resin particles are preferably at least one selected from thermoplastic resin particles, thermoreactive resin particles, resin particles having polymerizable groups, microcapsules containing hydrophobic compounds, and microgels (crosslinked resin particles). Among the above, resin particles having polymerizable groups are preferred. In particularly preferred embodiments, the resin particles contain at least one ethylenically unsaturated group. Such resin particles can improve the printing durability of exposed areas and the on-press developability of unexposed areas.

[0368] -Thermoplastic resin particles-

[0369] Preferred thermoplastic resin particles include those described in Research Disclosure No. 33303, January 1992, Japanese Patent Application Laid-Open Nos. 9-123387, 9-131850, 9-171249, and 9-171250, or European Patent No. 931647.

[0370] Specific examples of the resin constituting the thermoplastic resin particles include homopolymers or copolymers of monomers (e.g., ethylene, styrene, vinyl chloride, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, vinylidene chloride, acrylonitrile, vinylcarbazole, and acrylates or methacrylates having a polyalkylene structure), or mixtures thereof.

[0371] From the viewpoint of ink acceptability and UV printing durability, the thermoplastic resin particles preferably contain a resin having a structural unit composed of an aromatic vinyl compound and a structural unit having a nitrile group.

[0372] The aromatic vinyl compound may be any compound having a structure in which a vinyl group is bonded to an aromatic ring. Examples of the aromatic vinyl compound include styrene compounds and vinylnaphthalene compounds. Preferred aromatic vinyl compounds are styrene compounds, with styrene being more preferred. Examples of the styrene compound include styrene, p-methylstyrene, p-methoxystyrene, β-methylstyrene, p-methyl-β-methylstyrene, α-methylstyrene, and p-methoxy-β-methylstyrene.

[0373] From the perspective of ink adherence, the content of the structural units formed from the aromatic vinyl compound is preferably greater than the content of the structural units having nitrile groups described below. The content of the structural units formed from the aromatic vinyl compound is more preferably 15% to 85% by mass, and particularly preferably 30% to 70% by mass, relative to the total mass of the thermoplastic resin in the thermoplastic resin particles.

[0374] The constituent unit having a nitrile group is preferably introduced using a monomer having a nitrile group. As a monomer having a nitrile group, for example, an acrylonitrile compound can be mentioned. As a preferred example of a monomer having a nitrile group, (meth)acrylonitrile can be mentioned. As a constituent unit having a nitrile group, a constituent unit formed from (meth)acrylonitrile is preferably used.

[0375] From the perspective of ink adherence, the content of the structural units having nitrile groups is preferably less than the content of the structural units formed from the aromatic vinyl compound. The content of the structural units having nitrile groups is preferably 55% to 90% by mass, more preferably 60% to 85% by mass, relative to the total mass of the thermoplastic resin in the thermoplastic resin particles.

[0376] When the thermoplastic resin particles contain a resin having a structural unit formed from an aromatic vinyl compound and a structural unit having a nitrile group, the content ratio of the structural unit formed from the aromatic vinyl compound and the structural unit having a nitrile group (i.e., structural unit formed from the aromatic vinyl compound:structural unit having a nitrile group) is preferably 5:5 to 9:1, more preferably 6:4 to 8:2, on a mass basis.

[0377] From the perspective of UV printing durability and chemical resistance, the thermoplastic resin contained in the thermoplastic resin particles preferably further includes a structural unit formed from an N-vinyl heterocyclic compound. Examples of the N-vinyl heterocyclic compound include N-vinyl pyrrolidone, N-vinyl carbazole, N-vinyl pyrrole, N-vinyl phenothiazine, N-vinyl succinimide, N-vinyl phthalimide, N-vinyl caprolactam, and N-vinylimidazole. N-vinyl pyrrolidone is preferred as the N-vinyl heterocyclic compound.

[0378] The content of the structural units formed from the N-vinyl heterocyclic compound 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 thermoplastic resin in the thermoplastic resin particles.

[0379] The thermoplastic resin contained in the thermoplastic resin particles may have a structural unit having an acidic group. However, from the perspective of on-press developability and ink acceptability, the thermoplastic resin contained in the thermoplastic resin particles preferably does not have a structural unit having an acidic group. Specifically, the content of structural units having an acidic group in the thermoplastic resin relative to the total mass of the thermoplastic resin in the thermoplastic resin particles is preferably 20% by mass or less, more preferably 10% by mass or less, and particularly preferably 5% by mass or less. The lower limit of this content is not particularly limited and may be 0% by mass.

[0380] The acid value of the thermoplastic resin contained in the thermoplastic resin particles is preferably 160 mgKOH / g or less, more preferably 80 mgKOH / g or less, and particularly preferably 40 mgKOH / g or less. The lower limit of the acid value is not limited and may be 0 mgKOH / g. In the present invention, the acid value is determined by a measurement method in accordance with JIS K0070:1992.

[0381] From the perspective of ink adherence, the thermoplastic resin contained in the thermoplastic resin particles may have a structural unit containing a hydrophobic group. Examples of the hydrophobic group include alkyl groups, aryl groups, and aralkyl groups. Examples of the structural unit containing a hydrophobic group include preferably a structural unit formed from an alkyl (meth)acrylate compound, an aryl (meth)acrylate compound, or an aralkyl (meth)acrylate compound, and more preferably a structural unit formed from an alkyl (meth)acrylate compound.

[0382] The content of the structural unit having a hydrophobic group in the thermoplastic resin contained in the thermoplastic resin particles is preferably 5 to 50% by mass, more preferably 10 to 30% by mass, relative to the total mass of the thermoplastic resin in the thermoplastic resin particles.

[0383] From the viewpoint of UV printing durability and on-machine developability, the thermoplastic resin contained in the thermoplastic resin particles preferably has a hydrophilic group. Regarding the hydrophilic group, as long as it has a hydrophilic structure, there is no restriction. As the hydrophilic group, for example, an acid group (for example, a carboxyl group), a hydroxyl group, an amino group, a nitrile group and a group with a polyalkylene oxide structure can be mentioned. From the viewpoint of UV printing durability and on-machine developability, the hydrophilic group is preferably a group with a polyalkylene oxide structure, a group with a polyester structure or a sulfonic acid group, more preferably a group with a polyalkylene oxide structure or a sulfonic acid group, and particularly preferably a group with a polyalkylene oxide structure.

[0384] From the viewpoint of on-press developability, the polyalkylene oxide structure is preferably a polyethylene oxide structure, a polypropylene oxide structure, or a poly(ethylene oxide / propylene oxide) structure.

[0385] From the viewpoint of on-press developability, the group having a polyalkylene oxide structure preferably has a polypropylene oxide structure, and more preferably has a polyethylene oxide structure and a polypropylene oxide structure.

[0386] From the viewpoint of on-press developability, the number of alkylene oxide structures in the polyalkylene oxide structure is preferably 2 or more, more preferably 5 or more, further preferably 5 to 200, and particularly preferably 8 to 150.

[0387] The hydrophilic group is preferably a group represented by the following formula PO.

[0388] [Chemical formula 30]

[0389]

[0390] 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.

[0391] In the formula PO, L P Each independently preferably is ethylene, 1-methylethylene or 2-methylethylene, and more preferably is ethylene.

[0392] In the formula PO, R P It 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.

[0393] In the formula PO, n is preferably an integer of 1-10, and more preferably an integer of 1-4.

[0394] The content of the structural unit having a hydrophilic group is preferably 5% by mass to 60% by mass, more preferably 10% by mass to 30% by mass, relative to the total mass of the thermoplastic resin in the thermoplastic resin particles.

[0395] The resin contained in the thermoplastic resin particles may further have other structural units. Examples of the other structural units include structural units other than the above-mentioned structural units, for example, structural units formed from acrylamide compounds or vinyl ether compounds.

[0396] 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, relative to the total mass of the thermoplastic resin in the thermoplastic resin particles.

[0397] -Thermo-reactive resin particles-

[0398] Examples of the thermoreactive resin particles include resin particles having thermoreactive groups. The thermoreactive resin particles form hydrophobic regions by crosslinking due to a thermal reaction and by changes in functional groups during crosslinking.

[0399] Regarding the thermally reactive group, if a chemical bond is formed, it can be a functional group that performs any reaction, but is preferably a polymerizable group. As preferred thermally reactive groups, for example, there can be enumerated ethylenically unsaturated groups (for example, acryloyl, methacryloyl, vinyl and allyl groups) that perform free polymerization reactions, cationic polymerizable groups (for example, vinyl, vinyloxy, epoxy and oxetane groups), isocyanate groups or their blocks that perform addition reactions, epoxy, vinyloxy and functional groups with active hydrogen atoms (for example, amino, hydroxyl and carboxyl groups) that are the reaction targets of these, carboxyl groups that perform condensation reactions and hydroxyl or amino groups that are the reaction targets, and acid anhydrides that perform ring-opening addition reactions and amino or hydroxyl groups that are the reaction targets.

[0400] The resin having a heat-reactive group may be an addition polymerization type resin, an addition polymerization type resin or a condensation polymerization type resin. The resin having a heat-reactive group may be a thermoplastic resin.

[0401] -Microcapsules-

[0402] Preferred microcapsules include, for example, those described in Japanese Patent Application Laid-Open Nos. 2001-277740 and 2001-277742, which contain at least a portion of the components of the image recording layer (preferably a hydrophobic compound). The image recording layer comprising microcapsules as resin particles preferably contains the hydrophobic component (i.e., the hydrophobic compound) of the components of the image recording layer within the microcapsules, and contains a hydrophilic component (i.e., the hydrophilic compound) on the outside of the microcapsules.

[0403] -Microgel-

[0404] The microgel (cross-linked resin particles) can contain a portion of the components of the image-recording layer on at least one of the surface or interior of the microgel. In particular, reactive microgels having polymerizable groups on the surface of the microgel are preferred from the perspectives of the sensitivity of the lithographic printing plate precursor and the printing durability of the resulting lithographic printing plate. To obtain microcapsules containing the components of the image-recording layer, known synthesis methods can be applied.

[0405] -Addition Polymerization Resin Particles-

[0406] From the viewpoint of printing durability, stain resistance, and storage stability of the resulting lithographic printing plate, the resin particles are preferably addition-polymerized resin particles obtained by reacting a polyvalent isocyanate compound, which is an adduct of a polyvalent phenol compound having two or more hydroxyl groups in its molecule and isophorone diisocyanate, with a compound having active hydrogen.

[0407] As the polyphenol compound, a compound having a plurality of benzene rings having a phenolic hydroxyl group is preferred.

[0408] The compound having active hydrogen is preferably a polyol compound or a polyamine compound, more preferably a polyol compound, and still more preferably at least one selected from propylene glycol, glycerin, and trimethylolpropane.

[0409] Water can be used as the active hydrogen compound. When water is used as the active hydrogen compound, amines generated by the reaction of isocyanate groups with water can form urea bonds to form particles.

[0410] As resin particles obtained by reacting a polyvalent isocyanate compound which is an adduct of a polyvalent phenol compound having two or more hydroxyl groups in the molecule and isophorone diisocyanate, and a compound having active hydrogen, preferably, the resin particles described in paragraphs 0230 to 0234 of International Publication No. 2018 / 043259 are mentioned.

[0411] From the perspectives of printing durability, ink adherence, on-press developability, and suppressing development residue during on-press development, the resin particles preferably comprise an addition-polymerized resin having a urea bond, more preferably comprise an addition-polymerized resin having a structure obtained by reacting at least an isocyanate compound represented by the following formula (Iso) with water, and particularly preferably comprise an addition-polymerized resin having a structure obtained by reacting at least an isocyanate compound represented by the following formula (Iso) with water, and having a polyethylene oxide structure and a polypropylene oxide structure as the polyoxyalkylene structure. Furthermore, the particles comprising an addition-polymerized resin having a urea bond are preferably microgels.

[0412] [Chemical Formula 31]

[0413]

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

[0415] As an example of the reaction of an isocyanate compound represented by formula (Iso) with water, the reaction shown below can be cited. The example of the reaction shown below is an example in which n=0 and a 4,4-isomer is used. As shown below, when the isocyanate compound represented by formula (Iso) is reacted with water, a portion of the isocyanate groups is hydrolyzed by water to generate amino groups, and the generated amino groups react with the isocyanate groups to generate urea bonds, forming a dimer. Furthermore, the reaction shown below is repeated to form an addition-polymerized resin having a urea bond. Furthermore, by adding a compound reactive with an isocyanate group (i.e., a compound having active hydrogen: for example, an alcohol compound and an amine compound) to the reaction shown below, it is also possible to introduce the structures of the alcohol compound, amine compound, etc. into the addition-polymerized resin having a urea bond. As the compound having active hydrogen, the compounds having active hydrogen described above are preferably cited.

[0416] [Chemical Formula 32]

[0417]

[0418] Furthermore, the addition-polymerized resin having a urea bond preferably has an ethylenically unsaturated group, and more preferably has a group represented by the following formula (PETA).

[0419] [Chemical Formula 33]

[0420]

[0421] In formula (PETA), the wavy line portion indicates the bonding position to other structures.

[0422] -Addition polymerization type resin particles-

[0423] From the perspective of printing durability and solvent resistance of the resulting lithographic printing plate, the resin particles are preferably addition-polymerized resin particles having a hydrophobic main chain and comprising: i) a structural unit having a nitrile group directly bonded to the hydrophobic main chain; and ii) a structural unit having a pendant group containing a hydrophilic polyalkylene oxide segment. Specifically, the particles described in paragraph 0156 of JP-A-2019-64269 are preferred.

[0424] -Group represented by formula Z-

[0425] The resin particles preferably have a group represented by the following formula Z as a hydrophilic group.

[0426] *-QWY: Type Z

[0427] 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, and Y represents a monovalent group having a hydrophilic structure or a monovalent group having a hydrophobic structure. Either W or Y has a hydrophilic structure, and * represents a bonding site with another structure. Preferably, any of the hydrophilic structures included in Formula Z comprises a polyalkylene oxide structure.

[0428] Q in formula Z is preferably a divalent linking group having 1 to 20 carbon atoms, and more preferably a divalent linking group having 1 to 10 carbon atoms.

[0429] Q in formula Z is preferably an alkylene group, an arylene group, an ester bond, an amide bond, or a group obtained by combining two or more of these, and more preferably a phenylene group, an ester bond, or an amide bond.

[0430] The divalent group having a hydrophilic structure in W of formula Z is preferably a group having a polyalkylene oxide structure, more preferably a polyalkyleneoxy group or a group having -CH2CH2NR bonded to one end of the polyalkyleneoxy group. W -group. W represents a hydrogen atom or an alkyl group.

[0431] The divalent group having a hydrophobic structure in W of formula Z is preferably -R WA -、-OR WA -O-、-R W NR WA -NR W -、-OC(=O)-R WA -O-or-OC(=O)-R WA -O-. 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 having 7 to 120 carbon atoms (i.e., a divalent group obtained by removing one hydrogen atom from an alkylaryl group), or an aralkylene group having 7 to 120 carbon atoms. W represents a hydrogen atom or an alkyl group.

[0432] The monovalent group having a hydrophilic structure in Y of formula Z is preferably -OH, -C(=O)OH, a polyalkyleneoxy group having a hydrogen atom or an alkyl group at the end, or a polyalkyleneoxy group having a hydrogen atom or an alkyl group at the other end thereof bonded with -CH2CH2N(R W The monovalent group having a hydrophilic structure is preferably a monovalent group having a polyalkylene oxide structure, and preferably a -CH2 CH 2 N(R W )-group. W represents a hydrogen atom or an alkyl group.

[0433] The monovalent group having a hydrophobic structure in Y of formula Z is preferably a linear, branched or cyclic alkyl group having 6 to 120 carbon atoms, a halogenated alkyl group having 6 to 120 carbon atoms, an aryl group having 6 to 120 carbon atoms, an alkaryl group (alkylaryl group) having 7 to 120 carbon atoms, an aralkyl group having 7 to 120 carbon atoms, -OR WB 、-C(=O)OR WB or -OC(=O)R WB . R WB It represents an alkyl group having 6 to 20 carbon atoms.

[0434] In resin particles having a group represented by Formula Z, from the perspectives of printing durability, ink adhesion, and on-press developability, W is preferably 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 terminated with a hydrogen atom or an alkyl group. Furthermore, the group represented by Formula Z can function as a dispersing group that improves the dispersibility of the resin particles.

[0435] -Resin particles having polymerizable groups-

[0436] From the perspectives of printing durability and on-press developability, the resin particles preferably have polymerizable groups (preferably ethylenically unsaturated groups), and more preferably include resin particles having polymerizable groups on the surface. The use of resin particles having polymerizable groups can easily suppress plate wear (preferably UV plate wear) and improve printing durability (preferably UV printing durability).

[0437] From the viewpoint of printing durability, resin particles are preferably resin particles having a hydrophilic group and a polymerizable group. The polymerizable group may be a cationic polymerizable group or a free radical polymerizable group, but from the viewpoint of reactivity, it is preferably a free radical polymerizable group. As a polymerizable group, as long as it is a group that can be polymerized, there is no particular restriction, but from the viewpoint of reactivity, preferably an ethylenically unsaturated group, more preferably a vinylphenyl (styryl), (meth)acryloyloxy or (meth)acrylamide, especially preferably (meth)acryloyloxy. Furthermore, the resin constituting the resin particles having a polymerizable group preferably has a constituent unit having a polymerizable group. In addition, the polymerizable group can be introduced into the surface of the resin particles by a polymer reaction.

[0438] -Synthesis of resin particles-

[0439] There are no particular limitations on the method for synthesizing the resin particles, as long as the method can utilize the various resins described above to synthesize the particles. Examples of the method for synthesizing the resin particles include known methods for synthesizing resin particles, such as emulsion polymerization, suspension polymerization, dispersion polymerization, soap-free polymerization, and microemulsion polymerization. The resin particles can be synthesized using known methods for synthesizing microcapsules or known methods for synthesizing microgels (crosslinked resin particles).

[0440] (Average particle size)

[0441] The average particle size of the particles is preferably 0.01 μm to 3.0 μm, more preferably 0.03 μm to 2.0 μm, and particularly preferably 0.10 μm to 1.0 μm. By setting the average particle size of the particles within the above range, good resolution and stability over time can be obtained. Regarding the average particle size of the particles, the measurement is performed by a light scattering method, or an electron micrograph of the particles is taken, the particle size of a total of 5,000 particles is measured on the photograph, and the average value is calculated. In addition, for non-spherical particles, it is set to the circle equivalent diameter of the particles on the photograph. Regarding the average particle size of the particles in the present invention, unless otherwise specified, it is the volume average particle size.

[0442] (Particle content)

[0443] The image recording layer may contain one or more types of particles. From the viewpoint of developability and printing durability, the content of the particles (preferably resin particles) relative to the total mass of the image recording layer is preferably 5% to 90% by mass, more preferably 10% to 90% by mass, further preferably 20% to 90% by mass, and particularly preferably 50% to 90% by mass.

[0444] [Other ingredients]

[0445] The image recording layer may contain components other than the components described above as other components. Examples of other components include a binder polymer, a developer, a chain transfer agent, a low-molecular-weight hydrophilic compound, a sensitizer, and other additives.

[0446] (Binder polymer)

[0447] The image recording layer may contain a binder polymer as needed. In the present invention, "binder polymer" refers to a polymer other than resin particles, i.e., a polymer that is not in the form of particles. The ammonium salt-containing polymer in the sensitizer and the polymer used as a surfactant are excluded from the binder polymer.

[0448] As the binder polymer, known binder polymers used in the image recording layer of a lithographic printing plate precursor (e.g., (meth)acrylic resins, polyvinyl acetal resins, and polyurethane resins) can be preferably used. Below, as an example of a binder polymer, a binder polymer used in an on-press development type lithographic printing plate precursor (hereinafter also referred to as an on-press development binder polymer) is described in detail.

[0449] As a binder polymer for on-machine development, a binder polymer having an alkylene oxide chain is preferred. The binder polymer having an alkylene oxide chain may have a poly(alkylene oxide) site in the main chain or the side chain. Furthermore, the binder polymer having an alkylene oxide chain may be a graft polymer having a poly(alkylene oxide) in the side chain, or a block copolymer of a block consisting of a repeating unit containing a poly(alkylene oxide) and a block consisting of a repeating unit not containing a (alkylene oxide). In the case where the binder polymer has a poly(alkylene oxide) site in the main chain, a polyurethane resin is preferred. As a polymer having a poly(alkylene oxide) site in the side chain, for example, (meth) acrylic resin, polyvinyl acetal resin, polyurethane resin, polyurea resin, polyimide resin, polyamide resin, epoxy resin, polystyrene resin, novolac type phenolic resin, polyester resin, synthetic rubber and natural rubber can be cited, and (meth) acrylic resin is particularly preferred.

[0450] Preferred examples of binder polymers include polymer compounds having a core portion composed of a polyfunctional thiol having 6 or more functional groups and 10 or less functional groups, a polymer chain bonded to the core portion via a thioether bond, and a polymer chain having a polymerizable group (hereinafter also referred to as a star-shaped polymer compound). Examples of star-shaped polymer compounds that can be preferably used include compounds described in Japanese Patent Application Laid-Open No. 2012-148555.

[0451] Examples of star-shaped polymer compounds include compounds having polymerizable groups such as ethylenically unsaturated bonds, as described in Japanese Patent Application Laid-Open No. 2008-195018, on the main chain or side chain, preferably on the side chain, for improving the film strength of the image area. The polymerizable groups in the star-shaped polymer compound form crosslinks between molecules of the star-shaped polymer compound, accelerating curing.

[0452] As the polymerizable group, an ethylenically unsaturated group (e.g., (meth)acrylate, vinyl, allyl, and vinylphenyl (styryl)) or an epoxy group is preferred. From the perspective of polymerization reactivity, a (meth)acrylate, vinyl, or vinylphenyl (styryl) is more preferred, and a (meth)acrylate is particularly preferred. These groups can be introduced into the binder polymer through polymer reaction or copolymerization. Specifically, for example, the reaction of a polymer having a carboxyl group on 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.

[0453] The weight average molecular weight (Mw) of the binder polymer as a polystyrene conversion value based on the GPC method is preferably 2,000 or more, more preferably 5,000 or more, and particularly preferably 10,000 to 300,000.

[0454] As the binder polymer, a hydrophilic polymer such as polyacrylic acid or polyvinyl alcohol described in JP-A-2008-195018 may be used in combination as needed. Furthermore, a lipophilic polymer and a hydrophilic polymer may also be used in combination.

[0455] The image-recording layer may contain one kind alone or two or more kinds of binder polymers.

[0456] The content of the binder polymer is preferably 1% by mass to 90% by mass, more preferably 5% by mass to 80% by mass, relative to the total mass of the image recording layer.

[0457] (Developer)

[0458] The image-recording layer preferably contains a developer, more preferably an acid developer. The image-recording layer preferably contains a colorless compound (also referred to as a colorless pigment) as the developer.

[0459] In the present invention, the "developer" refers to a compound having a property of developing or fading color by stimulation of light, acid, or the like, and changing the color of the image recording layer, for example.

[0460] In the present invention, an "acid developer" refers to a compound that develops or decolorizes the image recording layer upon heating while receiving protons from an electron-accepting compound (e.g., an acid). Preferred acid developers include, for example, colorless compounds having a partial skeleton such as a lactone, lactam, sultone, spiropyran, ester, or amide, which undergo rapid ring-opening or cleavage upon contact with an electron-accepting compound.

[0461] Examples of the acid developer include the compounds described in paragraphs 0184 to 0191 of JP-A-2019-18412.

[0462] From the viewpoint of color development, the color developer is preferably at least one selected from the group consisting of spiropyran compounds, spirooxazine compounds, spirolactone compounds, and spirolactam compounds.

[0463] The hue of the pigment after color development preferably has a maximum absorption wavelength in the range of 450 nm to 650 nm from the viewpoint of visibility. The hue is preferably red, purple, blue, or dark green.

[0464] From the viewpoint of the visual recognition of color development and exposure portion, acid developer is preferably a colorless pigment. About colorless pigment, as long as it is a pigment with a colorless structure, there is no particular restriction, but preferably has a spiral structure, more preferably has a spirolactone ring structure. And, from the viewpoint of the visual recognition of color development and exposure portion, colorless pigment is preferably a colorless pigment with a phthalide structure or a fluoran parent structure. From the viewpoint of the visual recognition of color development and exposure portion, the colorless pigment with a phthalide structure or a fluoran parent structure is preferably a compound represented by any one of the following formulas (Le-1) to (Le-3), more preferably a compound represented by the following formula (Le-2).

[0465] [Chemical Formula 34]

[0466]

[0467] In formula (Le-1) to formula (Le-3), ERG each independently represents an electron-donating group, X1 to X4 each independently represents a hydrogen atom, a halogen atom or a dialkylaniline group, and X5 to X 10 Each independently represents a hydrogen atom, a halogen atom or a monovalent organic group, Y1 and Y2 each independently represent C or N, when Y1 is N, X1 does not exist, when Y2 is N, X4 does not exist, Ra1 represents a hydrogen atom, an alkyl group or an alkoxy group, and Rb1 to Rb4 each independently represent a hydrogen atom, an alkyl group or an aryl group.

[0468] From the viewpoint of color development and visual recognition of the exposed portion, the electron-donating group in the ERGs of formula (Le-1) to (Le-3) 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 an arylamino group, a monoalkylmonoarylamino group or a diarylamino group, and particularly preferably an arylamino group or a monoalkylmonoarylamino group.

[0469] From the viewpoint of color development and visibility of the exposed portion, X1 to X4 in Formulae (Le-1) to (Le-3) are each independently preferably a hydrogen atom or a chlorine atom, and more preferably a hydrogen atom.

[0470] From the viewpoint of color development and visibility of the exposed portion, X5 to X6 in formula (Le-2) or formula (Le-3) are 10 Each independently selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl group, an aryl group, 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 and a cyano group is preferred; a hydrogen atom, a halogen atom, an alkyl group, an aryl group, an alkoxy group and an aryloxy group is more preferred; a hydrogen atom, a halogen atom, an alkyl group and an aryl group is further preferred; and a hydrogen atom is particularly preferred.

[0471] From the viewpoint of color development and visibility of the exposed portion, it is preferred that at least one of Y1 and Y2 in Formulas (Le-1) to (Le-3) is C, and it is more preferred that both Y1 and Y2 are C.

[0472] From the viewpoint of color development and visibility of the exposed portion, Ra1 in formula (Le-3) is preferably an alkyl group or an alkoxy group, more preferably an alkoxy group, and particularly preferably a methoxy group.

[0473] From the viewpoint of color development and visibility of the exposed portion, Rb1 to Rb4 in formula (Le-1) are each independently preferably a hydrogen atom or an alkyl group, more preferably an alkyl group, and particularly preferably a methyl group.

[0474] Furthermore, from the perspective of color development and visual recognition of the exposed portion, the colorless pigment having a phthalide structure or a fluoran parent structure is preferably a compound represented by any one of the following formulas (Le-4) to (Le-6), and more preferably a compound represented by the following formula (Le-5).

[0475] [Chemical Formula 35]

[0476]

[0477] In formulas (Le-4) to (Le-6), ERG independently represents an electron-donating group, X1 to X4 independently represent a hydrogen atom, a halogen atom or a dialkylaniline group, Y1 and Y2 independently represent C or N, when Y1 is N, X1 does not exist, and when Y2 is N, X4 does not exist, Ra1 represents a hydrogen atom, an alkyl group or an alkoxy group, and Rb1 to Rb4 independently represent a hydrogen atom, an alkyl group or an aryl group.

[0478] ERG, X1~X4, Y1, Y2, Ra1 and Rb1~Rb4 in formula (Le-4) to formula (Le-6) have the same meanings as ERG, X1~X4, Y1, Y2, Ra1 and Rh1~Rb4 in formula (Le-1) to formula (Le-3), and the preferred embodiments are also the same.

[0479] Moreover, from the perspective of color development and visual recognition of the exposed portion, the colorless pigment having a phthalide structure or a fluoran matrix structure is preferably a compound represented by any one of the following formulas (Le-7) to (Le-9), and more preferably a compound represented by the following formula (Le-8).

[0480] [Chemical Formula 36]

[0481]

[0482] In formulas (Le-7) to (Le-9), X1 to X4 each independently represent a hydrogen atom, a halogen atom or a dialkylaniline group, Y1 and Y2 each independently represent C or N, when Y1 is N, X1 does not exist, and when Y2 is N, X4 does not exist, Ra1 to Ra4 each independently represent 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, and Rc1 and Rc2 each independently represent an aryl group.

[0483] X1 to X4, Y1 and Y2 in formulas (Le-7) to (Le-9) have the same meanings as X1 to X4, Y1 and Y2 in formulas (Le-1) to (Le-3), and preferred embodiments are also the same.

[0484] From the viewpoint of color development and visibility of the exposed portion, Ra1 to Ra4 in formula (Le-7) are each independently preferably an alkyl group or an alkoxy group, more preferably an alkoxy group, and particularly preferably a methoxy group.

[0485] From the perspective of color development and visual recognition of the exposed portion, Rb1 to Rb4 in formulas (Le-7) to (Le-9) are each independently preferably a hydrogen atom, an alkyl group, or an aromatic group substituted by an alkyl group or an alkoxy group, more preferably a hydrogen atom or an alkyl group, and particularly preferably a hydrogen atom or a methyl group.

[0486] From the viewpoint of color development and visibility of the exposed portion, Rc1 and Rc2 in formula (Le-8) are each independently preferably a phenyl group or an alkylphenyl group, and more preferably a phenyl group.

[0487] In formula (Le-8), it is preferred that X1 to X4 are hydrogen atoms, and Y1 and Y2 are C from the viewpoint of color development and visibility of the exposed portion.

[0488] From the viewpoint of color development and visibility of the exposed portion, in formula (Le-8), Rb1 and Rb2 are each independently preferably a hydrogen atom, an alkyl group, or an aryl group substituted with an alkyl group or an alkoxy group, and more preferably a hydrogen atom or an alkyl group.

[0489] The alkyl groups in formulae (Le-1) to (Le-9) may be linear or branched. The alkyl groups in formulae (Le-1) to (Le-9) may have a ring structure.

[0490] The number of carbon atoms in the alkyl group in formula (Le-1) to formula (Le-9) is preferably 1 to 20, more preferably 1 to 8, further preferably 1 to 4, and particularly preferably 1 or 2.

[0491] The number of carbon atoms in the aryl group in formula (Le-1) to formula (Le-9) is preferably 6 to 20, more preferably 6 to 10, and particularly preferably 6 to 8.

[0492] Each group in Formula (Le-1) to Formula (Le-9) (e.g., a monovalent organic group, an alkyl group, an aryl group, a dialkylanilino group, an alkylamino group, and an alkoxy group) 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, and a cyano group. The substituent may be further substituted by the substituents described above.

[0493] Examples of the colorless dye having a phthalide structure or a fluoran matrix structure that can be preferably used include the following compounds.

[0494] [Chemical Formula 37]

[0495]

[0496] [Chemical Formula 38]

[0497]

[0498] [Chemical Formula 39]

[0499]

[0500] [Chemical Formula 40]

[0501]

[0502] [Chemical Formula 41]

[0503]

[0504] As the acid developer, a commercially available product (i.e., a commercially available product) can also be used. Commercially available products include, for example, ETAC, RED500, RED520, CVL, S-205, BLACK305, BLACK400, BLACK100, BLACK500, H-7001, GREEN300, NIRBLACK78, BLUE220, H-3035, BLUE203, ATP, H-1046, and H-2114 (all from Fukui Yamada Chemical Co., Ltd.). o ., Ltd.), ORANGE-DCF, Vermilion-DCF, PINK-DCF, RED-DCF, BLMB, CVL, GREEN-DCF and TH-107 (all manufactured by HODOGAYA CHEMICAL CO., LTD.), ODB, ODB-2, ODB-4, ODB-250, ODB-BlackXV, Blue-63, Blue-502, GN-169, GN-2, Green-118, Red-40 and Red-8 (all manufactured by YAMAMOTO CHEMICALS INC.), and crystal violet lactone (manufactured by Tokyo Chemical Industry Co., Ltd.). Among these commercially available products, ETAC, S-205, BLACK305, BLACK400, BLACK100, BLACK500, H-7001, GREEN300, NIRB LACK78, H-3035, ATP, H-1046, H-2114, GREEN-DCF, Blue-63, GN-169, and crystal violet lactone are preferred because the films formed therefrom have good visible light absorptivity.

[0505] As the colorless dye that can be preferably used, the following compounds can be mentioned from the viewpoint of color development and visibility of the exposed portion.

[0506] [Chemical Formula 42]

[0507]

[0508] The image recording layer may contain one or more color developers, and the content of the color developer is preferably 0.5% to 10% by mass, more preferably 1% to 5% by mass, relative to the total mass of the image recording layer.

[0509] (chain transfer agent, low molecular weight hydrophilic compound, sensitizer and other additives)

[0510] Components that can be used in the image recording layer are described, for example, in paragraph 0082 of Japanese Patent Application Laid-Open No. 2019-162855, the contents of which are incorporated herein by reference.

[0511] [Formation method]

[0512] The image recording layer can be formed by a known method (eg, coating method). The coating amount (solid content) of the image recording layer is preferably 100 mg / m 2 ~3,000 mg / m 2 , more preferably 300 mg / m 2 ~1,500 mg / m 2 .

[0513] <<Base Coating>>

[0514] The on-machine development type lithographic printing plate precursor involved in one embodiment of the present invention preferably has a primer layer between the image recording layer and the support. In the technical field related to the present invention, the primer layer is sometimes also referred to as an intermediate layer. The adhesion between the support and the image recording layer is enhanced in the exposed portion of the primer layer, and the image recording layer is easily peeled off from the support in the unexposed portion of the primer layer. Therefore, the primer layer does not impair the printing durability and helps to improve the developability. In addition, in the case of infrared laser exposure, the primer layer acts as a heat insulating layer, thereby preventing the heat generated by the exposure from diffusing to the support and decreasing the sensitivity.

[0515] Examples of the compound contained in the undercoat layer include polymers having adsorptive groups and hydrophilic groups that can be adsorbed on the support surface. To improve adhesion to the image recording layer, the compound contained in the undercoat layer is preferably a polymer having adsorptive groups and hydrophilic groups, and further having a crosslinking group. The compound contained in the undercoat layer may be a low molecular weight compound or a polymer. Two or more compounds contained in the undercoat layer may be mixed and used as needed.

[0516] When the compound contained in the primer layer is a polymer, the polymer is preferably a copolymer of a monomer having an adsorptive group, a monomer having a hydrophilic group, and a monomer having a crosslinkable group.

[0517] As the adsorptive group, a phenolic hydroxyl group, a carboxyl group, -PO3H2, -OPO3H2, -CONHSO2-, -SO2NHSO2- or -COCH2COCH3 is preferred.

[0518] As the hydrophilic group, a sulfo group or a salt thereof, or a salt of a carboxyl group is preferred.

[0519] As the crosslinkable group, an acryloyl group, a methacryloyl group, an acrylamide group, a methacrylamide group or an allyl group is preferable.

[0520] The polymer may have crosslinkable groups introduced by forming a salt between a polar substituent of the polymer and a compound having a substituent with a charge opposite to that of the polar substituent and an ethylenically unsaturated bond. The polymer may further be copolymerized with monomers other than those mentioned above, preferably hydrophilic monomers.

[0521] Specifically, preferably enumerate the phosphorus compound with olefinic double bond reactive group of putting down in writing in the silane coupling agent with the olefinic double bond reactive group that can addition polymerization and the 2-304441 communique of Japanese Patent Laid-Open No. 10-282679 communique of Japanese Patent Laid-Open No. 10-282679. Also can preferably use the low molecule or the macromolecular compound with crosslinking group (being preferably olefinic unsaturated bond group) and with the interactional functional group and hydrophilic group of support surface that put down in writing in the 2005-238816 communique of Japanese Patent Laid-Open No. 2005-125749 communique of Japanese Patent Laid-Open No. 2006-239867 communique of Japanese Patent Laid-Open No. 2006-215263 communique of Japanese Patent Laid-Open No. 2006-215263. More preferable examples include polymers having an adsorbable group adsorbable on the surface of a support, a hydrophilic group, and a crosslinkable group, as described in Japanese Patent Application Laid-Open Nos. 2005-125749 and 2006-188038.

[0522] The content of the ethylenically unsaturated bond group in the polymer contained in the primer layer is preferably 0.1 mmol to 10.0 mmol, more preferably 0.2 mmol to 5.5 mmol per 1 g of the polymer.

[0523] The weight average molecular weight (Mw) of the polymer contained in the primer layer is preferably 5,000 or more, and more preferably 10,000 to 300,000.

[0524] [Hydrophilic compounds]

[0525] From the viewpoint of developability, the undercoat layer preferably contains a hydrophilic compound. As the hydrophilic compound, for example, a known hydrophilic compound used in an undercoat layer can be used.

[0526] Preferred hydrophilic compounds include, for example, phosphonic acids having an amino group such as carboxymethylcellulose and dextrin, organic phosphonic acid, organic phosphoric acid, organic phosphinic acid, amino acids, and hydrochlorides of amines having a hydroxyl group.

[0527] In addition, as preferred hydrophilic compounds, for example, compounds having an amino group or a functional group having polymerization inhibition ability and a group that interacts with the surface of the support (for example, 1,4-diazabicyclo[2.2.2]octane (DABCO), 2,3,5,6-tetrahydroxy-p-benzoquinone, chloranil, sulfophthalic acid, ethylenediaminetetraacetic acid (EDTA) or its salts, hydroxyethylethylenediaminetriacetic acid or its salts, dihydroxyethylethylenediaminediacetic acid or its salts and hydroxyethyliminodiacetic acid, etc. or their salts) can also be mentioned.

[0528] From the viewpoint of scratch staining inhibition, the undercoat layer preferably contains a hydroxycarboxylic acid or a salt thereof as a hydrophilic compound.

[0529] In the present invention, "hydroxycarboxylic acid" is a general term for organic compounds having one or more carboxyl groups and one or more hydroxyl groups in one molecule, and is also called hydroxy acid, oxyacid, hydroxycarboxylic acid, or alkyd acid (see Iwanami Physical and Chemical Dictionary, 5th edition, published by Iwanami Shoten (1998)).

[0530] The hydroxycarboxylic acid or a salt thereof is preferably represented by the following formula (HC).

[0531] R HC (OH) mhc (COOM HC ) nhc :Formula (HC)

[0532] In formula (HC), R HC Represents an organic group with MHC+NHC valence, M HC Each independently represents a hydrogen atom, an alkali metal or an onium atom, and mhc and nhc each independently represent an integer greater than or equal to 1. When nhc is greater than or equal to 2, M may be the same or different.

[0533] In formula (HC), as R HCThe organic group with MHC+NHC valence represented by is, for example, a hydrocarbon group with MHC+NHC valence. The hydrocarbon group may have a substituent and / or a linking group. Examples of the hydrocarbon group include groups with MHC+NHC valence derived from aliphatic hydrocarbons (e.g., alkylene, alkanetriyl, alkanetetrayl, alkanepentayl, alkenylene, alkenetriyl, alkenetetrayl, alkenepentayl, alkynylene, alkynetriyl, alkynetetrayl, and alkynepentayl) and groups with MHC+NHC valence derived from aromatic hydrocarbons (e.g., arylene, arenetriyl, arenetetrayl, and arenepentayl). Examples of the substituent include alkyl, alkenyl, alkynyl, aralkyl, and aryl groups. Specific examples of the substituent include 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, 2-norbornyl, methoxymethyl, methoxyethoxyethyl, allyloxymethyl, phenoxymethyl, acetoxymethyl, benzoyloxy Methyl, benzyl, phenethyl, α-methylbenzyl, 1-methyl-1-phenethyl, p-methylbenzyl, cinnamyl, allyl, 1-propenylmethyl, 2-butenyl, 2-methylallyl, 2-methylpropenylmethyl, 2-propynyl, 2-butynyl, 3-butynyl, phenyl, biphenyl, naphthyl, tolyl, xylyl, mesityl, cumenyl, methoxyphenyl, ethoxyphenyl, phenoxyphenyl, acetoxyphenyl, benzoyloxyphenyl, methoxycarbonylphenyl, ethoxycarbonylphenyl, and phenoxycarbonylphenyl. The linking group is a linking group composed of at least one atom selected from hydrogen atoms, carbon atoms, oxygen atoms, nitrogen atoms, sulfur atoms, and halogen atoms. The number of atoms in the linking group is preferably 1 to 50. Specific examples of the linking group include alkylene, substituted alkylene, arylene, and substituted arylene. The linking group may have a structure in which a plurality of the above-mentioned divalent groups are linked through at least one selected from an amide bond, an ether bond, a urethane bond, a urea bond, and an ester bond.

[0534] In formula (HC), as represented by M HC Examples of the alkali metal represented by M include lithium, sodium and potassium, with sodium being particularly preferred. HC Examples of onium include ammonium, phosphonium, and sulfonium, with ammonium being particularly preferred. HC An alkali metal or onium is preferred, and an alkali metal is more preferred.

[0535] In formula (HC), the total number of MHC and NHC is preferably 3 or more, more preferably 3 to 8, and particularly preferably 4 to 6.

[0536] The molecular weight of the hydroxycarboxylic acid or its salt is preferably 600 or less, more preferably 500 or less, and particularly preferably 300 or less. The molecular weight of the hydroxycarboxylic acid or its salt is preferably 76 or more.

[0537] Examples of the hydroxycarboxylic acid or the hydroxycarboxylic acid constituting the salt thereof include gluconic acid, glycolic acid, lactic acid, tartronic acid, hydroxybutyric acid (e.g., 2-hydroxybutyric acid, 3-hydroxybutyric acid, and γ-hydroxybutyric acid), malic acid, tartaric acid, citramalic acid, citric acid, isocitric acid, leucine, mevalonic acid, pantoic acid, ricinoleic acid, ricinoleic acid, hydroxyethyl ester, quinic acid, shikimic acid, monohydroxybenzoic acid derivatives (e.g., salicylic acid, oleic acid (homosalicylic acid, hydroxyethyl ester), hydroxybenzoic acid, ... The present invention also includes but is not limited to benzoic acid, ...

[0538] As the hydroxycarboxylic acid constituting the hydroxycarboxylic acid or the salt of the hydroxycarboxylic acid, from the viewpoint of scratch stain inhibition, a compound having two or more hydroxyl groups is preferred, a compound having three or more hydroxyl groups is more preferred, a compound having five or more hydroxyl groups is further preferred, and a compound having 5 to 8 hydroxyl groups is particularly preferred.

[0539] As the compound having one carboxyl group and two or more hydroxyl groups, gluconic acid or shikimic acid is preferred. As the compound having two or more carboxyl groups and one hydroxyl group, citric acid or malic acid is preferred. As the compound having two or more carboxyl groups and two or more hydroxyl groups, tartaric acid is preferred. Among the above, gluconic acid is particularly preferred as the hydroxycarboxylic acid.

[0540] The primer layer may contain one or more hydrophilic compounds. When the primer layer contains a hydrophilic compound (preferably a hydroxycarboxylic acid or a salt thereof), the content of the hydrophilic compound (preferably a hydroxycarboxylic acid or a salt thereof) relative to the total mass of the primer layer is preferably 0.01% to 50% by mass, more preferably 0.1% to 40% by mass, and particularly preferably 1.0% to 30% by mass.

[0541] -Application scope of hydrophilic compounds-

[0542] As described below, the hydrophilic compound (preferably a hydroxycarboxylic acid or a salt thereof) can be used as a component not only of the primer layer but also of layers other than the primer layer.

[0543] From the perspective of scratch stain inhibition, the hydrophilic compound (preferably a hydroxycarboxylic acid or a salt thereof) is preferably contained in a layer on an aluminum support, which is a type of support. The layer on the aluminum support is preferably located on the side where the image recording layer is formed. Furthermore, the layer on the aluminum support is more preferably a layer in contact with the aluminum support. Preferred examples of the layer on the aluminum support (preferably a layer in contact with the aluminum support) include an undercoat layer and an image recording layer.

[0544] The hydrophilic compound (preferably a hydroxycarboxylic acid or a salt thereof) may be contained in a layer other than the layer in contact with the aluminum support (e.g., the outermost layer or the image recording layer). In one embodiment, the image recording layer preferably contains a hydroxycarboxylic acid or a salt thereof from the viewpoint of scratch staining inhibition.

[0545] It is also preferred to cite a method in which the surface of the image recording layer side of the aluminum support is surface-treated using a composition (for example, an aqueous solution, etc.) containing at least a hydroxycarboxylic acid or a salt thereof. In the above method, at least a portion of the treated hydroxycarboxylic acid or a salt thereof can be detected in a state contained in a layer (for example, an image recording layer or a primer layer) on the image recording layer side in contact with the aluminum support. By containing a hydroxycarboxylic acid or a salt thereof on the image recording layer side in contact with the aluminum support, the surface of the image recording layer side of the aluminum support can be hydrophilized. Furthermore, by containing a hydroxycarboxylic acid or a salt thereof on the image recording layer side in contact with the aluminum support, the contact angle with water based on the air drop method on the surface of the image recording layer side of the aluminum support can be easily set to 110° or less, and the scratch contamination inhibition property is excellent.

[0546] [Other ingredients]

[0547] The undercoat layer may contain, in addition to the undercoat layer compound, for example, a chelating agent, a secondary or tertiary amine, and a polymerization inhibitor in order to prevent staining over time.

[0548] [Formation method]

[0549] The primer layer can be formed by a known method (eg, coating method). The coating amount (solid content) of the primer layer is preferably 0.1 mg / m 2 ~300 mg / m 2 , more preferably 5 mg / m 2 ~200 mg / m 2 .

[0550] <<Purpose>>

[0551] An on-press developable lithographic printing plate precursor according to one embodiment of the present invention is a lithographic printing plate precursor that can be used for on-press development. The on-press developable lithographic printing plate precursor according to one embodiment of the present invention can be formed into a lithographic printing plate through, for example, the exposure step and on-press development step described below. The resulting lithographic printing plate can be used in various printing methods.

[0552] <Method for producing lithographic printing plate and lithographic printing method>

[0553] A method for producing a lithographic printing plate according to one embodiment of the present invention includes: exposing an on-press developable lithographic printing plate precursor according to one embodiment of the present invention to an image pattern (hereinafter also referred to as an "exposure step"); and supplying at least one selected from a printing ink and a fountain solution on a printing press to remove the image recording layer from non-image areas (hereinafter also referred to as an "on-press development step"). According to one embodiment of the present invention, a method for producing a lithographic printing plate using an on-press developable lithographic printing plate precursor that suppresses discoloration caused by ozone exposure can be provided.

[0554] A lithographic printing method according to one embodiment of the present invention includes: exposing an on-press developable lithographic printing plate precursor according to one embodiment of the present invention to an image pattern (i.e., an exposure step); supplying at least one of a printing ink and a fountain solution to a printing press to remove the image recording layer from non-image areas, thereby producing a lithographic printing plate (i.e., an on-press development step); and printing using the resulting lithographic printing plate (hereinafter also referred to as a "printing step"). According to one embodiment of the present invention, a printing method using an on-press developable lithographic printing plate precursor that suppresses discoloration caused by ozone exposure can be provided.

[0555] Hereinafter, each step will be described in detail.

[0556] <<Exposure Process>>

[0557] In the exposure step, the on-press developable lithographic printing plate precursor is exposed imagewise. Imagewise exposure of the on-press developable lithographic printing plate precursor forms exposed and unexposed areas. For example, when a negative image-recording layer is used as the image-recording layer, the exposed areas of the negative image-recording layer form the image areas, and the unexposed areas of the negative image-recording layer form the non-image areas. The on-press developable lithographic printing plate precursor used in the lithographic printing plate production method and the printing method is the same as the on-press developable lithographic printing plate precursor described above in the section "On-press developable lithographic printing plate precursor."

[0558] The lithographic printing plate precursor is preferably exposed in an image-like manner by laser exposure through a transparent original image having a line image or a halftone dot image, or by laser beam scanning based on digital data.

[0559] The wavelength of the light source is preferably 750 nm to 1,400 nm. Solid-state lasers and semiconductor lasers that radiate infrared light are preferred as light sources with a wavelength of 750 nm to 1,400 nm. For infrared lasers, the output power is preferably 100 mW or higher, the exposure time per pixel is preferably within 20 microseconds, and the irradiation energy is preferably 10 mJ / cm 2 ~300mJ / cm 2 In order to shorten the exposure time, it is preferable to use a multi-beam laser device. The exposure mechanism may be, for example, an inner drum method, an outer drum method, or a flatbed method.

[0560] Exposure can be performed, for example, using a plate-making machine by conventional methods. Exposure can be performed on the printing press after the lithographic printing plate precursor is mounted on the printing press. Exposure can also be performed before the lithographic printing plate precursor is mounted on the printing press.

[0561] <<On-press development process>>

[0562] In the on-press development step, at least one selected from printing ink and fountain solution is supplied on the printing press to remove the image recording layer from the non-image area.

[0563] The on-press development process is performed after the lithographic printing plate precursor is mounted on the printing press. If at least one of printing ink and fountain solution is supplied to the printing press, the printing ink and / or fountain solution dissolves or disperses the image-recording layer in non-image areas (e.g., unexposed areas) during the initial printing phase, exposing the hydrophilic surface. Meanwhile, the image-recording layer in the remaining image areas (e.g., exposed areas) forms an oleophilic surface that accepts the printing ink. The lithographic printing plate precursor that has undergone on-press development can be used directly for multiple printings.

[0564] During the on-press development process, either printing ink or fountain solution may be supplied first. To prevent contamination of the fountain solution by components of the removed image recording layer, it is preferred to supply printing ink first. Known printing inks can be used as printing inks. Preferred printing inks include, for example, oil-based inks or ultraviolet-curable inks (UV inks). Known fountain solutions can be used as fountain solutions.

[0565] <<Printing Process>>

[0566] In the printing process, printing is performed using the obtained lithographic printing plate. In the printing process, information can be printed on a recording medium using the obtained lithographic printing plate. The printing process preferably includes a process of supplying printing ink to the lithographic printing plate and printing information on the recording medium. Examples of printing inks used for printing include the printing inks described in the above-mentioned "on-press development process." Examples of recording media include paper. Examples of information include characters, numbers, symbols, images, and patterns. In the printing process, a fountain solution can be supplied as needed. The printing process can be performed continuously without stopping the printing press.

[0567] <<Other Processes>>

[0568] In the method for producing a lithographic printing plate or the lithographic printing method according to one embodiment of the present invention, the entire surface of the lithographic printing plate precursor can be heated before the exposure process, during the exposure process, or between the exposure process and the on-press development process, as needed. By heating as described above, the image forming reaction in the image recording layer can be promoted, and advantages such as improved sensitivity and printing durability, and stabilization of sensitivity can be achieved. Regarding heating before the on-press development process, it is preferably carried out under mild conditions of 150°C or less. By heating under the conditions described above, for example, the problem of solidification of the non-image area can be prevented. In the heating after the on-press development process, it is preferably used very strong conditions, for example, heating is preferably carried out in the range of 100°C to 500°C. By heating within the temperature range described above, a sufficient image enhancement effect can be obtained, and problems such as deterioration of the support and thermal decomposition of the image area can be suppressed.

[0569] Example

[0570] Hereinafter, the present invention will be described in detail with reference to Examples. In addition, "parts" and "%" are based on mass unless otherwise specified.

[0571] <Raw materials>

[0572] The following lists the raw materials used in the Examples and Comparative Examples. In the following description, compounds represented by the same symbols refer to the same compounds. Repeated compound descriptions (e.g., chemical structures and production methods) are sometimes omitted.

[0573] <<Support (1)>>

[0574] A 0.3 mm thick aluminum alloy plate of material 1S was subjected to mechanical roughening (brush method) (Aa) described in paragraph 0126 of JP-A-2012-158022 to desmearing in an acidic aqueous solution (Ai) described in paragraph 0134.

[0575] Next, the treatment conditions of the first-stage anodizing treatment (Aj) described in paragraph 0135 to the third-stage anodizing treatment (Am) described in paragraph 0138 of Japanese Patent Application Laid-Open No. 2012-158022 were appropriately adjusted to form an anodic oxide film, thereby obtaining a support (1).

[0576] In addition, water washing was performed between all treatment steps, and drainage was performed using nip rollers after the water washing.

[0577] The details of the obtained support body (1) are summarized below.

[0578] L on the surface of microporous anodic oxide film * a * b * Lightness L in the color system * Value: 83

[0579] The average diameter of the large-diameter pores in the micropores at the surface of the oxide film is 35 nm (depth is 100 nm).

[0580] Average diameter of the small-diameter pores in the micropores at the connecting position: 10 nm (depth 1,000 nm)

[0581] Ratio of the depth of the large-diameter hole to the average diameter of the large-diameter hole: 2.9

[0582] <<Supporting Body (2)>>

[0583] (a) Alkali etching treatment

[0584] The aluminum plate was etched by spraying a caustic soda aqueous solution with a caustic soda concentration of 26% by mass and an aluminum ion concentration of 6.5% by mass at a temperature of 70°C. The plate was then rinsed with water using a spray. The surface was then electrochemically roughened to a concentration of 5 g / m2 of aluminum dissolved thereon. 2 .

[0585] (b) Decontamination treatment using an acidic aqueous solution (first decontamination treatment)

[0586] Next, decontamination treatment was performed using an acidic aqueous solution. A 150 g / L sulfuric acid solution was used. The solution temperature was 30°C. The acidic aqueous solution was sprayed onto the aluminum plate using a sprayer for 3 seconds. The plate was then rinsed with water.

[0587] (c) Electrochemical roughening treatment

[0588] Next, electrochemical roughening treatment was performed using an electrolyte solution with a hydrochloric acid concentration of 14 g / L, an aluminum ion concentration of 13 g / L, and a sulfuric acid concentration of 3 g / L, with alternating current. The electrolyte temperature was 30° C. Aluminum chloride was added to adjust the aluminum ion concentration.

[0589] The waveform of the AC current is a sine wave with symmetrical positive and negative waveforms, a frequency of 50 Hz, a 1:1 ratio between the anode reaction time and the cathode reaction time in one cycle of the AC current, and a current density of 75 A / dm2 based on the peak current of the AC current waveform. 2 The total amount of electricity consumed by the aluminum plate in the anode reaction is 450C / dm 2 For electrolysis, the current was applied at 112.5C / dm 2 This was done in four steps. A carbon electrode was used as the counter electrode for the aluminum plate. The aluminum plate was then rinsed with water.

[0590] (d) Alkali etching treatment

[0591] The aluminum plate after electrochemical roughening treatment was etched by spraying a caustic soda aqueous solution with a caustic soda concentration of 5% by mass and an aluminum ion concentration of 0.5% by mass at a temperature of 45°C. The amount of aluminum dissolved on the surface after electrochemical roughening treatment was 0.2 g / m 2 Then, a water washing process was performed.

[0592] (e) Decontamination treatment using an acidic aqueous solution

[0593] Next, a decontamination treatment was performed using an acidic aqueous solution. Specifically, the acidic aqueous solution was sprayed onto the aluminum plate using a sprayer for 3 seconds. The acidic aqueous solution used for decontamination had a sulfuric acid concentration of 170 g / L and an aluminum ion concentration of 5 g / L. The solution temperature was 30°C.

[0594] (f) Stage 1 anodizing treatment

[0595] use Figure 3 The anodizing treatment apparatus 610 based on direct current electrolysis of the structure shown in the figure performed the first stage of anodizing treatment (also referred to as the first anodizing treatment). Specifically, the first anodizing treatment was performed under the conditions of the "first anodizing treatment" column shown in Table 1 below, and an anodized film of a predetermined film amount was formed.

[0596] The following, Figure 3 The anodizing treatment apparatus 610 shown will be described.

[0597] exist Figure 3 In the anodizing apparatus 610 shown, the aluminum plate 616 is as shown in FIG. Figure 3The aluminum plate 616 is transported as indicated by the arrow in the middle. In a power supply tank 612 containing an electrolyte 618, the aluminum plate 616 is charged with a (+) charge by a power supply electrode 620. Within the power supply tank 612, the aluminum plate 616 is transported upward by rollers 622, redirected downward by nip rollers 624, and then transported to an electrolytic treatment tank 614 containing an electrolyte 626, where it is redirected horizontally by rollers 628. The aluminum plate 616 then passes through an electrolytic electrode 630, receiving a (-) charge, thereby forming an anodic oxide film on its surface. After leaving the electrolytic treatment tank 614, the aluminum plate 616 is transported to subsequent processes. In anodizing apparatus 610, a direction-changing mechanism is formed by rollers 622, nip rollers 624, and rollers 628. Aluminum sheet 616 is conveyed in a mountain-shaped and inverted U-shaped pattern between power supply tank 612 and electrolytic treatment tank 614 by rollers 622, nip rollers 624, and rollers 628. Power supply electrode 620 and electrolytic electrode 630 are connected to a DC power supply 634. A tank wall 632 is disposed between power supply tank 612 and electrolytic treatment tank 614.

[0598] (g) Hole expansion treatment

[0599] The anodized aluminum plate was immersed in a caustic soda aqueous solution having a temperature of 40°C, a caustic soda concentration of 5% by mass, and an aluminum ion concentration of 0.5% by mass under the conditions shown in Table 1 below to perform pore expansion. The plate was then washed with water using a sprayer.

[0600] (h) Second anodizing treatment

[0601] use Figure 3 The anodizing treatment apparatus 610 based on direct current electrolysis of the structure shown in the figure performed the second stage of anodizing treatment (also referred to as the second anodizing treatment). Specifically, the second anodizing treatment was performed under the conditions of the "second anodizing treatment" column shown in Table 1 below, and an anodized film of a predetermined film amount was formed.

[0602] In this way, the support body (2) was manufactured.

[0603] The L of the surface of the microporous anodic oxide film of the obtained support (2) is * a * b * Lightness L in the color system * The average diameter and depth of the large-diameter pores in the micropores at the surface of the oxide film, the average diameter (nm) and depth of the small-diameter pores in the micropores at the connecting position, the depth (nm) of the large-diameter pores and the small-diameter pores, the micropore density, and the thickness of the anodic oxide film from the bottom of the small-diameter pores to the surface of the aluminum plate (also called the film thickness) are summarized in Table 2.

[0604] In Table 1, the film amount (AD) in the "First Anodic Oxidation Treatment" column and the film amount (AD) in the "Second Anodic Oxidation Treatment" column represent the film amount obtained in each treatment. The electrolyte used was an aqueous solution containing the components listed in Table 1.

[0605] [Table 1]

[0606]

[0607] [Table 2]

[0608]

[0609] <<Support (3)>>

[0610] A Hydro 1052 aluminum alloy sheet with a thickness of 0.28 mm (available from Norsk Hydro ASA, Norway) was used as an aluminum plate, and surface treatment was performed by the following steps to change the concentration of the electrochemical roughening treatment solution and the amount of alkali etching after the electrochemical roughening treatment to produce a support (3).

[0611] -Alkali etching treatment-

[0612] The aluminum plate was etched by spraying a caustic soda aqueous solution with a caustic soda concentration of 26% by mass and an aluminum ion concentration of 6.5% by mass at a temperature of 70°C. The plate was then rinsed with water using a spray. The surface was then electrochemically roughened to a concentration of 5 g / m2 of aluminum dissolved thereon. 2 .

[0613] - Decontamination treatment using an acidic aqueous solution-

[0614] Next, decontamination treatment was performed using an acidic aqueous solution. A 150 g / L sulfuric acid solution was used. The solution temperature was 30°C. The acidic aqueous solution was sprayed onto the aluminum plate using a sprayer for 3 seconds. The plate was then rinsed with water.

[0615] -Electrochemical roughening treatment-

[0616] Next, electrochemical roughening treatment was performed using an electrolyte solution with a hydrochloric acid concentration of 14 g / L, an aluminum ion concentration of 13 g / L, and a sulfuric acid concentration of 3 g / L, with alternating current. The electrolyte temperature was 30° C. Aluminum chloride was added to adjust the aluminum ion concentration.

[0617] The waveform of the AC current is a sine wave with symmetrical positive and negative waveforms, a frequency of 50 Hz, a 1:1 ratio between the anode reaction time and the cathode reaction time in one cycle of the AC current, and a current density of 75 A / dm2 based on the peak current of the AC current waveform. 2The total amount of electricity consumed by the aluminum plate in the anode reaction is 450C / dm 2 For electrolysis, the current was applied at 112.5C / dm 2 This was done in four steps. A carbon electrode was used as the counter electrode for the aluminum plate. The aluminum plate was then rinsed with water.

[0618] -Alkali etching treatment-

[0619] The aluminum plate after electrochemical roughening treatment was etched by spraying a caustic soda aqueous solution having a caustic soda concentration of 5% by mass and an aluminum ion concentration of 0.5% by mass at 45° C. with a sprayer.

[0620] - Decontamination treatment using an acidic aqueous solution-

[0621] Next, a decontamination treatment was performed using an acidic aqueous solution. Specifically, the acidic aqueous solution was sprayed onto the aluminum plate using a sprayer for 3 seconds. The acidic aqueous solution used for decontamination had a sulfuric acid concentration of 170 g / L and an aluminum ion concentration of 5 g / L. The solution temperature was 35°C.

[0622] - Anodizing treatment -

[0623] Next, the aluminum plate was anodized twice, with each anodizing bath containing approximately 100 liters of anodizing solution. The first anodizing condition was an electrolyte concentration of 175 g / liter, a temperature of 60°C, and a current density of 5.8 A / dm 2 The second anodizing condition was an electrolyte concentration of 280 g / liter, a temperature of 23°C, and a current density of 10 A / dm 2 The first anodizing process for forming the outer aluminum oxide layer was performed using phosphoric acid as the electrolyte, and the second anodizing process for forming the inner aluminum oxide layer was performed using sulfuric acid as the electrolyte.

[0624] <<Support (4)>>

[0625] To remove rolling oil from the surface of a 0.3 mm thick aluminum plate (material: JIS A 1050), a degreasing treatment was performed using a 10 mass % sodium aluminate aqueous solution at 50°C for 30 seconds, and then a brush with three bundles of nylon bristles with a bristle diameter of 0.3 mm and a pumice-water suspension with a median particle size of 25 μm (specific gravity 1.1 g / cm 3) to grain the aluminum surface and then clean it with water. The plate was immersed in a 25% by mass sodium hydroxide aqueous solution at 45°C for 9 seconds to etch it, and then rinsed with water. It was then immersed in a 20% by mass nitric acid aqueous solution at 60°C for 20 seconds and rinsed with water. The amount of etching on the frosted surface at this time was about 3g / m 2 .

[0626] Next, electrochemical roughening treatment was continuously performed using an AC voltage of 60 Hz. The electrolyte at this time was a 1% by mass aqueous solution of nitric acid (containing 0.5% by mass of aluminum ions), and the liquid temperature was 50°C. Regarding the AC power waveform, a trapezoidal rectangular wave AC with a time TP of 0.8 msec, a duty ratio of 1:1, and a current value from zero to peak was used, and electrochemical roughening treatment was performed using a carbon electrode as a counter electrode. Ferrite was used as an auxiliary anode. The current density was 30 A / dm 2 , so that 5% of the current flowing from the power supply is diverted to the auxiliary anode. The amount of electricity in nitric acid electrolysis is 175C / dm when the aluminum plate is the anode. 2 Then, a spray-based water wash was performed.

[0627] Next, a 0.5 mass % aqueous solution of hydrochloric acid (containing 0.5 mass % of aluminum ions) and an electrolyte at a temperature of 50°C were used, and the charge was 50 C / dm when the aluminum plate was the anode. 2 Under the conditions of , electrochemical roughening treatment was carried out in the same way as nitric acid electrolysis, and then spray water washing was performed.

[0628] Next, 15 mass % sulfuric acid (containing 0.5 mass % aluminum ions) was used as an electrolyte on the plate at a current density of 15 A / dm 2 Set 2.5g / m 2 After the DC anodized film was formed, it was washed with water and dried.

[0629] Then, in order to ensure the hydrophilicity of the non-image area, a silicate treatment was performed at 60°C for 10 seconds using a 2.5% by mass sodium silicate No. 3 aqueous solution, and then washed with water to obtain a support (4). The adhesion amount of Si was 10 mg / m 2 The centerline average roughness (Ra) of the support (4) was measured using a needle having a diameter of 2 μm and was found to be 0.51 μm.

[0630] <<Undercoat coating liquid (1)>>

[0631] · Undercoat compound (P-1, 11% by mass aqueous solution): 0.10502 parts

[0632] Sodium gluconate: 0.07000 parts

[0633] Surfactant (EMALEX710, manufactured by NIHON EMULSION Co., Ltd.): 0.00159 parts

[0634] Preservative (Biohope L, manufactured by K.I. Chemical Industry Co., Ltd.): 0.00149 parts

[0635] Water: 2.87190 parts

[0636] [Chemical Formula 43]

[0637]

[0638] <<Undercoat coating liquid (2)>>

[0639] · Undercoat compound (P-1, 11% by mass aqueous solution): 0.10502 parts

[0640] · Hydroxyethyl diiminodiacetic acid: 0.01470 parts

[0641] Sodium EDTA: 0.06575 parts

[0642] Surfactant (EMALEX710, manufactured by NIHON EMULSION Co., Ltd.): 0.00159 parts

[0643] Preservative (Biohope L, manufactured by K.I. Chemical Industry Co., Ltd.): 0.00149 parts

[0644] Water: 2.86144 parts

[0645] <<Undercoat coating liquid (3)>>

[0646] The undercoat layer coating liquid (1) described in paragraph 0136 of Japanese Patent Application Laid-Open No. 2012-66577 was used as the undercoat layer coating liquid (3).

[0647] <<Image Recording Layer Coating Liquid (1)>>

[0648] Infrared absorber (IR-1): 0.02000 parts

[0649] Color developer (S-1): 0.02500 parts

[0650] Electron-accepting polymerization initiator (Int-1): 0.11000 parts

[0651] Electron-donating polymerization initiator (TPB): 0.02500 parts

[0652] Polymerizable compound (M-1): 0.27500 parts

[0653] Anionic surfactant (A-1): 0.00600 parts

[0654] Fluorine-based surfactant (W-1): 0.00416 parts

[0655] 2-Butanone: 4.3602 parts

[0656] 1-Methoxy-2-propanol: 4.4852 parts

[0657] Methanol: 2.2838 parts

[0658] Microgel solution 1: 2.3256 parts

[0659] [Chemical Formula 44]

[0660] IR-1

[0661]

[0662] The HOMO energy level of the infrared absorber (IR-1) is -5.35 eV. The LUMO energy level of the infrared absorber (IR-1) is -3.75 eV.

[0663] [Chemical Formula 45]

[0664] S-1

[0665]

[0666] [Chemical Formula 46]

[0667]

[0668] The HOMO energy level of the electron-accepting polymerization initiator (Int-1) was -6.70 eV. The LUMO energy level of the electron-accepting polymerization initiator (Int-1) was -3.08 eV.

[0669] [Chemical Formula 47]

[0670]

[0671] The HOMO energy level of the electron-donating polymerization initiator (TPB) is −5.90 eV.

[0672] [Chemical Formula 48]

[0673] A-1

[0674]

[0675] [Chemical Formula 49]

[0676] W-1

[0677]

[0678] [Synthesis Method of Polymerizable Compound M-1]

[0679] A mixed solution of Takenate D-160N (polyisocyanate-trimethylolpropane adduct, manufactured by Mitsui Chemicals, Inc., 4.7 parts), ARONIX M-403 (manufactured by TOAGOSEI CO., LTD., in an amount such that the NCO value of Takenate D-160N and the hydroxyl value of ARONIX M-403 are in a ratio of 1:1), tert-butylbenzoquinone (0.02 parts), and methyl ethyl ketone (11.5 parts) was heated to 65°C. NEOSTANN U-600 (bismuth-based polycondensation catalyst, manufactured by NITTO KASEI CO., LTD., 0.11 parts) was added to the reaction solution, and the mixture was heated at 65°C for 4 hours. The reaction solution was cooled to room temperature (25°C), and methyl ethyl ketone was added to synthesize a urethane acrylate solution having a solids content of 50% by mass. The urethane acrylate solution was subjected to molecular weight fractionation using a reusable GPC (equipment: LC908-C60, columns: JAIGEL-1H-40 and 2H-40 (manufactured by Japan Analytical Industry)) with tetrahydrofuran (THF) as the eluent. The weight average molecular weight was 20,000.

[0680] [Synthesis Method of Microgel Liquid 1]

[0681] Microgel solution 1 was synthesized by the following steps.

[0682] (Preparation of polyisocyanate compound)

[0683] To a suspension of isophorone diisocyanate (17.78 parts, 80 molar equivalents) and the following polyphenol compound (1) (7.35 parts, 20 molar equivalents) in ethyl acetate (25.31 parts) was added bismuth tris(2-ethylhexanoate) (NEOSTANN U-600, manufactured by NITTO KASEI CO., LTD., 0.043 parts) and stirred. When heat generation was suppressed, the reaction temperature was set to 50°C, and stirring was carried out for 3 hours to obtain an ethyl acetate solution (50% by mass) of the polyisocyanate compound (1).

[0684] [Chemical Formula 50]

[0685]

[0686] (Preparation of Microgels)

[0687] The following oil phase components and aqueous phase components were mixed and emulsified using a homogenizer at 12,000 rpm (revolutions per minute) for 10 minutes. The resulting emulsion was stirred at 45°C for 4 hours, and then a 10% by mass aqueous solution (5.20 g) of 1,8-diazabicyclo[5.4.0]undec-7-ene-octanoate (U-CAT SA102, manufactured by San-Apro Ltd.) was added. The mixture was stirred at room temperature for 30 minutes and allowed to stand at 45°C for 24 hours. The solid content concentration was adjusted to 20% by mass using distilled water to obtain an aqueous dispersion of microgel (1). The average particle size was measured by light scattering and was found to be 0.28 μm.

[0688] -Oil phase ingredients-

[0689] (Component 1) Ethyl acetate: 12.0 parts

[0690] (Component 2) 3.76 parts of an adduct prepared by adding mono-terminally methylated polyoxyethylene (1 molar equivalent, number of repeating oxyethylene units: 90) to trimethylolpropane (6 molar equivalents) and xylene diisocyanate (18 molar equivalents) (50% by mass ethyl acetate solution, manufactured by Mitsui Chemicals, Inc.)

[0691] (Component 3) Polyisocyanate compound (1) (as a 50% by mass ethyl acetate solution): 15.0 parts

[0692] (Component 4) 65% by mass ethyl acetate solution of dipentaerythritol pentaacrylate (SR-399, manufactured by Sartomer Company, Inc.): 11.54 parts

[0693] (Component 5) 10% by mass ethyl acetate solution of a sulfonate surfactant (PIONIN A-41-C, manufactured by Takemoto Oil & Fat Co., Ltd.): 4.42 parts

[0694] -Aqueous phase ingredients-

[0695] Distilled water: 46.87 parts

[0696] <<Image Recording Layer Coating Liquid (2)>>

[0697] Infrared absorber (IR-1): 0.00600 parts

[0698] Infrared absorber (IR-2): 0.0200 parts

[0699] Color developer (S-1): 0.02500 parts

[0700] Electron-accepting polymerization initiator (Int-1): 0.11000 parts

[0701] Electron-donating polymerization initiator (TPB): 0.02500 parts

[0702] Polymerizable compound (M-1): 0.27500 parts

[0703] Anionic surfactant (A-1): 0.09000 parts

[0704] Fluorine-based surfactant (W-1): 0.00416 parts

[0705] 2-Butanone: 4.9200 parts

[0706] 1-Methoxy-2-propanol: 3.1000 parts

[0707] Methanol: 2.7900 parts

[0708] Microgel liquid 2: 2.90700 parts

[0709] [Chemical Formula 51]

[0710] IR-2

[0711]

[0712] The HOMO energy level of the infrared absorber (IR-2) is -5.31 eV. The LUMO energy level of the infrared absorber (IR-2) is -3.78 eV.

[0713] [Synthesis Method of Microgel Liquid 2]

[0714] -Preparation of oil phase components-

[0715] A polyfunctional isocyanate compound (PM-200: manufactured by Wanhua Chemical Co.): 6.66 g; a 50% by mass ethyl acetate solution of "Takenate (registered trademark) D-116N (an adduct of trimethylolpropane (TMP), meta-xylylenediisocyanate (XDI), and polyethylene glycol monomethyl ether (E090) (the following structure)" manufactured by Mitsui Chemicals, Inc.): 5.46 g; a 65% by mass ethyl acetate solution of dipentaerythritol pentaacrylate (SR-399, manufactured by Sartomer Company, Inc.): 11.24 g; ethyl acetate: 14.47 g; and PIONIN (registered trademark) A-41-C: 0.45 g manufactured by Takemoto Oil & Fat Co., Ltd. were mixed and stirred at room temperature (25°C) for 15 minutes to obtain an oil phase component.

[0716] [Chemical Formula 52]

[0717]

[0718] -Preparation of aqueous phase components-

[0719] As the aqueous phase component, 47.2 g of distilled water was prepared.

[0720] -Microcapsule formation process-

[0721] The aqueous phase component was added to the oil phase component and mixed, and the obtained mixture was emulsified at 12,000 rpm for 16 minutes using a homogenizer to obtain an emulsion.

[0722] 16.8 g of distilled water was added to the obtained emulsion, and the obtained liquid was stirred at room temperature for 10 minutes.

[0723] The stirred liquid was then heated to 45°C and stirred for 4 hours while maintaining the liquid temperature at 45°C to distill off the ethyl acetate. Subsequently, 5.12 g of a 10% by mass aqueous solution of 1,8-diazabicyclo[5.4.0]undec-7-ene-octanoate (U-CAT SA102, manufactured by San-Apro Ltd.) was added, stirred at room temperature for 30 minutes, and allowed to stand at 45°C for 24 hours. The solids concentration was adjusted to 20% by mass with distilled water to obtain an aqueous dispersion of microgels. The volume average particle size of the microgels, measured using a laser diffraction / scattering particle size distribution analyzer LA-920 (manufactured by HORIBA, Ltd.), was 165 nm.

[0724] The obtained aqueous dispersion of microgel is referred to as microgel solution 2.

[0725] <<Image Recording Layer Coating Liquid (3)>>

[0726] Infrared absorber (IR-3): 0.026 parts

[0727] Electron-accepting polymerization initiator (Int-2): 0.060 parts

[0728] Electron-donating polymerization initiator (TPB): 0.050 parts

[0729] Polymerizable compound (M-2): 0.250 parts

[0730] Polymerizable compound (M-3): 0.250 parts

[0731] Adhesive (S-LEC BX-5Z, manufactured by SEKISUI CHEMICAL CO., LTD.): 0.150 parts

[0732] 1-Methoxy-2-propanol: 4.988 parts

[0733] 2-Butanone: 9.262 parts

[0734] [Chemical Formula 53]

[0735]

[0736] The HOMO energy level of the infrared absorber (IR-3) is -5.43 eV, and the LUMO energy level of the infrared absorber (IR-3) is -3.95 eV.

[0737] [Chemical Formula 54]

[0738] Int-2

[0739]

[0740] The HOMO energy level of the electron-accepting polymerization initiator (Int-2) was -6.96 eV. The LUMO energy level of the electron-accepting polymerization initiator (Int-2) was -3.18 eV.

[0741] [Chemical Formula 55]

[0742] M-2

[0743]

[0744] [Chemical Formula 56]

[0745] M-3

[0746]

[0747] [Chemical Formula 57]

[0748] S-LEC BX-5Z

[0749]

[0750] <<Image Recording Layer Coating Liquid (4)>>

[0751] Infrared absorber (IR-4): 0.027 parts

[0752] Infrared absorber (IR-5): 0.015 parts

[0753] Electron-accepting polymerization initiator (Int-3): 0.041 parts

[0754] Polymerizable compound (M-4): 0.100 parts

[0755] Polymerizable compound (M-5): 0.096 parts

[0756] Polymerizable compound (M-6): 0.096 parts

[0757] Polymer particles 1: 0.300 parts

[0758] Color developer (S-2): 0.041 parts

[0759] Hydroxypropyl cellulose: 0.030 parts

[0760] n-Propanol: 5.168 parts

[0761] 2-Butanone: 6.460 parts

[0762] 1-Methoxy-2-propanol: 1.615 parts

[0763] Methanol: 2.907 parts

[0764] [Chemical Formula 58]

[0765]

[0766] The HOMO energy level of the infrared absorber (IR-4) is -5.42 eV. The LUMO energy level of the infrared absorber (IR-4) is -3.82 eV.

[0767] [Chemical Formula 59]

[0768]

[0769] The HOMO energy level of the infrared absorber (IR-5) is -5.43 eV. The LUMO energy level of the infrared absorber (IR-5) is -3.84 eV.

[0770] [Chemical Formula 60]

[0771] Int-3

[0772]

[0773] The HOMO energy level of the electron-accepting polymerization initiator (Int-3) was -7.34 eV. The LUMO energy level of the electron-accepting polymerization initiator (Int-3) was -3.26 eV.

[0774] [Chemical Formula 61]

[0775]

[0776] [Chemical Formula 62]

[0777]

[0778] [Chemical Formula 63]

[0779]

[0780] [Chemical Formula 64]

[0781] Polymer particles 1

[0782]

[0783] In the chemical structural formula of the polymer particles 1, n is 40. The weight average molecular weight of the polymer particles 1 is 90,000.

[0784] [Chemical Formula 65]

[0785] S-2

[0786]

[0787] <<Image Recording Layer Coating Liquid (5)>>

[0788] The photosensitive liquid (1) described in paragraph 0139 of Japanese Patent Application Laid-Open No. 2012-66577 was used as the image recording layer coating liquid (5).

[0789] <<Outermost coating liquid>>

[0790] The composition of the outermost coating liquid is shown below. Specifically, the composition of the outermost coating liquid is shown in three tables. The numerical values ​​described in the columns of "Hydrophilic polymer", "Hydrophobic polymer", "Color-changing compound", and "Other" represent the added amount (unit: mass parts) excluding the solvent. "※1" described in the "Solvent" column means that the amount of solvent added is adjusted according to the added amount of "hydrophilic polymer", "hydrophobic polymer", "color-changing compound", and "Other" (including the solvent in the case of raw materials provided in the form of a solution or dispersion) so that the amount of coating liquid becomes 1 mass part.

[0791] [Table 3]

[0792]

[0793] [Table 4]

[0794]

[0795] [Table 5]

[0796]

[0797] The components described in Tables 3 to 5 are shown below.

[0798] [Hydrophilic polymer]

[0799] GOHSENX L3266: Sulfonic acid-modified polyvinyl alcohol, manufactured by Mitsubishi Chemical Corporation, Mw = 17,000

[0800] GOHSENX CKS-50: Sulfonic acid-modified polyvinyl alcohol, manufactured by Mitsubishi Chemical Corporation, Mw = 27,000

[0801] CMC1120: Carboxymethyl cellulose, manufactured by DAICEL FINECHEM LTD.

[0802] CMC1220: Carboxymethyl cellulose, manufactured by DAICEL FINECHEM LTD.

[0803] Mowiol 4-88: polyvinyl alcohol, manufactured by Merck

[0804] METOLOSE SM04: methylcellulose, manufactured by Shin-Etsu Chemical Co., Ltd., methoxyl substitution degree = 1.8

[0805] METOLOSE SM15: methylcellulose, manufactured by Shin-Etsu Chemical Co., Ltd., methoxyl substitution degree = 1.8

[0806] METOLOSE 60SH50: methylcellulose, manufactured by Shin-Etsu Chemical Co., Ltd., methoxyl substitution degree = 1.9

[0807] CELLOGEN 5A: Carboxymethyl cellulose, manufactured by DAICEL FINECHEM LTD.

[0808] Penon JE-66: Starch phosphate, manufactured by NIPPON STARCH CHEMICAL CO., LTD.

[0809] [Chemical Formula 66]

[0810] Water-soluble polymer 1

[0811]

[0812] [Hydrophobic polymer]

[0813] FS-102: Styrene-acrylic acid, manufactured by Nipponpaint Industrial Coatings Co., Ltd., Tg = 103°C

[0814] FS-106: Acrylic acid, manufactured by Nipponpaint Industrial Coatings Co., Ltd., Tg = 84°C

[0815] FS-107: Acrylic acid, manufactured by Nipponpaint Industrial Coatings Co., Ltd., Tg = 84°C

[0816] FS-201: Styrene-acrylic acid, manufactured by Nipponpaint Industrial Coatings Co., Ltd., Tg = 89°C

[0817] FS-501: Acrylic acid, manufactured by Nipponpaint Industrial Coatings Co., Ltd., Tg = 79°C

[0818] FS-701: Fluoroacrylic acid, manufactured by Nipponpaint Industrial Coatings Co., Ltd., Tg = 82°C

[0819] VONCOAT SK-105E: Styrene, manufactured by DIC Corporation, Tg = 100°C

[0820] · NEoCryl A-662: styrene-acrylic acid, manufactured by DSM Coating Resins, LLC., Tg = 95°C

[0821] · NEoCryl A-1092: styrene-acrylic acid, manufactured by DSM Coating Resins, LLC., Tg = 98°C

[0822] [Color-changing compounds]

[0823] The chemical structure of the color-changing compound is shown below.

[0824] [Chemical Formula 67]

[0825]

[0826] [Chemical Formula 68]

[0827]

[0828] [Chemical Formula 69]

[0829]

[0830] [other]

[0831] EMALEX710: Surfactant, polyoxyethylene lauryl ether, manufactured by NIHON EMULSION Co., Ltd.

[0832] <Examples 1 to 54 and Comparative Examples 1 to 5>

[0833] Lithographic printing plate precursors were prepared by the following procedures using the supports and coating solutions selected according to Tables 6 and 7. Layers marked with "-" in Tables 6 and 7 are layers not included in the lithographic printing plate precursors.

[0834] <<Formation of Primer Layer>>

[0835] On the support, the dry coating amount is 100 mg / m 2 The primer coating liquid is applied in a manner to form a primer layer.

[0836] <<Formation of Image Recording Layer>>

[0837] The image recording layer coating liquid was bar-coated on the support or the undercoat layer, and then dried at 120° C. for 40 seconds to form a dry coating weight of 1.3 g / m 2image recording layer.

[0838] <<Formation of the Outermost Layer>>

[0839] The outermost coating liquid was bar-coated on the image recording layer and then dried at 120°C for 60 seconds to form a dry coating weight of 0.7 g / m 2 The outermost layer.

[0840] <<Evaluation>>

[0841] [On-press development]

[0842] The prepared lithographic printing plate precursor was exposed using a Fujifilm Corporation Luxel PLATESETTER T-6000III equipped with an infrared semiconductor laser at an external drum speed of 1000 rpm, a laser output of 70%, and a resolution of 2400 dpi. The exposed image consisted of a solid image and a 50% dot pattern of FM screening with 20 μm dots. The exposed lithographic printing plate precursor was mounted on the plate cylinder of a Komori Corporation Lithrone 26 printing press without undergoing development. Using a fountain solution of Ecolity-2 (manufactured by Fujifilm Corporation) and tap water in a ratio of 2 / 98 (volume ratio) and Space Color Fusion G black ink (manufactured by DIC Corporation), the fountain solution and ink were supplied using the standard automatic print start method of a Lithrone 26, followed by on-press development. Then, 500 sheets were printed on Tokubishi Art paper (manufactured by Mitsubishi Paper Mills Limited, continuous weight 76.5 kg) at a printing speed of 10,000 sheets per hour. After on-press development of the unexposed areas of the image recording layer on the printing press was completed, the number of printed sheets required to achieve a state where ink transfer to the non-image areas was prevented was measured. The measurement results are shown in Tables 6 and 7. A smaller number of printed sheets indicates better on-press developability.

[0843] [Ink absorption]

[0844] A lithographic printing plate precursor exposed using the same exposure method as used in the evaluation of on-press developability was mounted on the plate cylinder of a Lithrone 26 printing press manufactured by Komori Corporation. Using a fountain solution of Ecolity-2 (manufactured by Fujifilm Corporation) / tap water = 2 / 98 (volume ratio) and Values-G(N) black ink (manufactured by Dainippon Ink and Chemicals, Inc.), the fountain solution and ink were supplied using the standard automatic print start method of the Lithrone 26, and after on-press development, 100 sheets were printed on Tokubishi Art paper (manufactured by Mitsubishi Paper Mills Limited, continuous weight 76.5 kg) at a printing speed of 10,000 sheets per hour. The number of sheets of printing paper required to achieve a predetermined standard concentration of ink transferred from the image portion of the lithographic printing plate to the printing paper was measured. The measurement results are shown in Tables 6 and 7. A smaller number of sheets of printing paper indicates better ink adherence.

[0845] [Table 6]

[0846]

[0847] [Table 7]

[0848]

[0849] The "hydrophobic polymer content" in Tables 6 and 7 represents the hydrophobic polymer content calculated based on the total mass of the outermost layer. The "hydrophobic polymer content" in Tables 6 and 7 can be evaluated as the area occupied by the hydrophobic polymer on the surface of the outermost layer.

[0850] The “contact angle of a water droplet” in Tables 6 and 7 represents the contact angle of a water droplet 2 seconds after it was dropped on the surface of the outermost layer by the air drop method.

[0851] The “contact angle of the oil droplet” in Tables 6 and 7 represents the contact angle of the oil droplet 2 seconds after it was dropped on the surface of the outermost layer by the aerial oil drop method.

[0852] The “exposed part” in Tables 6 and 7 indicates the exposure time at 110 mJ / cm 2 The energy density of the exposure was carried out based on infrared rays with a wavelength of 830 nm.

[0853] "ΔL" in Tables 6 and 7 indicates the average value of the sample at 110 mJ / cm 2 When exposure is performed with infrared light having a wavelength of 830 nm at an energy density of , the brightness change ΔL before and after exposure is observed.

[0854] As shown in Tables 6 and 7, in Examples 1 to 54, the ink adherence was not deteriorated and the on-press developability was excellent, compared with Comparative Examples 1 to 5.

[0855] The invention of Japanese Patent Application No. 2020-095071 filed on May 29, 2020 is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards described in this specification are incorporated herein by reference to the same extent as if each document, patent application, or technical standard were specifically and individually set forth by reference.

[0856] Explanation of symbols

[0857] 12a, 12b-aluminum support, 18-aluminum plate, 20a, 20b-anodized film, 22a, 22b-micropores, 24-large diameter pore portion, 26-small diameter pore portion, D: depth 610-anodizing treatment device, 612-power supply tank, 614-electrolytic treatment tank, 616-aluminum plate, 618, 626-electrolyte, 620-power supply electrode, 622, 628-rollers, 624-clamping roller, 630-electrolytic electrode, 632-tank wall, 634-DC power supply.

Claims

1. An on-press developing type lithographic printing plate precursor comprising, in order, a support, an image recording layer, and an outermost layer, The outermost layer comprises a hydrophobic polymer, and the area occupied by the hydrophobic polymer on the surface of the outermost layer is 25% or less. The contact angle of a water droplet dropped on the surface of the outermost layer by an aerial water drop method is less than 36° 2 seconds after the water droplet is dropped.

2. The on-press developing type lithographic printing plate precursor according to claim 1, which is subjected to a treatment at 110 mJ / cm 2 When exposure is performed with infrared rays having a wavelength of 830 nm at an energy density of 100 nm, the contact angle of a water droplet dropped on the surface of the outermost layer by an aerial water drop method is 32° or more 2 seconds after the water droplet is dropped.

3. An on-press developing type lithographic printing plate precursor comprising, in order, a support, an image recording layer and an outermost layer, The outermost layer comprises a hydrophobic polymer, and the area occupied by the hydrophobic polymer on the surface of the outermost layer is 25% or less. The contact angle of an oil droplet dropped on the surface of the outermost layer by an aerial oil drop method is 5° or more 2 seconds after the oil droplet is dropped on the surface of the outermost layer. At 110mJ / cm 2 When exposure is performed with infrared rays having a wavelength of 830 nm at an energy density of 100 nm, the contact angle of an oil droplet dropped on the surface of the outermost layer by an aerial oil drop method is less than 10° 2 seconds after the oil droplet is dropped.

4. The on-press development type lithographic printing plate precursor according to claim 1, wherein The hydrophobic polymer is in the form of particles.

5. The on-press development type lithographic printing plate precursor according to claim 1, wherein The glass transition temperature of the hydrophobic polymer is 60° C. or higher.

6. The on-press development type lithographic printing plate precursor according to claim 1, wherein The outermost layer comprises a hydrophilic polymer.

7. The on-press development type lithographic printing plate precursor according to claim 1, wherein The outermost layer includes a hydrophilic polymer, and the content of the hydrophilic polymer is greater than the content of the hydrophobic polymer.

8. The on-press development type lithographic printing plate precursor according to claim 1, wherein The outermost layer comprises a color-changing compound.

9. The on-press developing type lithographic printing plate precursor according to claim 8, which is developed at 110 mJ / cm 2 When the exposure is performed with infrared rays having a wavelength of 830 nm at an energy density of , a brightness change ΔL before and after the exposure is 2.0 or more.

10. The on-press development type lithographic printing plate precursor according to claim 8, wherein The color-changing compound includes a compound that develops color upon exposure to infrared rays.

11. The on-press developing type lithographic printing plate precursor according to claim 8, wherein The color-changing compound includes a decomposable compound that decomposes upon exposure to infrared rays.

12. The on-press development type lithographic printing plate precursor according to claim 8, wherein The color-changing compound is anthocyanin.

13. The on-press development type lithographic printing plate precursor according to claim 8, wherein The color-changing compound is a compound represented by the following formula 1-1, In formula 1-1, R 1 represents a group represented by any one of the following formulas 2 to 4, R 11 ~R 18 Each independently represents a hydrogen atom, a halogen atom, -R a 、-OR b 、-SR c or -NR d R e , R a ~R e Each independently represents a hydrocarbon group, A1, A2 and multiple R 11 ~R 18 are optionally 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 represents an integer from 0 to 5, n 11 and n 12 The total of n is 2 or more, 13 and n 14 Each independently represents 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, Za represents a counter ion for neutralizing the charge, In formula 2 to formula 4, R 20 、R 30 、R 41 and R 42 Each independently represents an alkyl group or an aryl group, Zb represents a counter ion for neutralizing the charge, and the wavy line represents a bonding site with L.

14. The on-press development type lithographic printing plate precursor according to claim 8, wherein The color-changing compound is a compound represented by the following formula 1-2, In formula 1-2, R 1 represents a group represented by any one of the following formulas 2 to 4, R 19 ~R 22 Each independently represents a hydrogen atom, a halogen atom, -R a 、-OR b 、-CN、-SR c or -NR d R e , R 23 and R 24 Each independently represents -R a , R a ~R e Each independently represents a hydrocarbon group, R 19 With R 20 、R 21 With R 22 or R 23 With R 24 They are optionally linked to form a monocyclic or polycyclic ring, and L represents an oxygen atom, a sulfur atom or -NR 10 -, R 10 represents a hydrogen atom, an alkyl group or an aryl group, R d1 ~R d4 、W 1 and W 2 Each independently represents an alkyl group optionally having a substituent, Za represents a counter ion for neutralizing the charge, In formula 2 to formula 4, R 20 、R 30 、R 41 and R 42 Each independently represents an alkyl group or an aryl group, Zb represents a counter ion for neutralizing the charge, and the wavy line represents a bonding site with L.

15. The on-press development type lithographic printing plate precursor according to claim 8, wherein The color-changing compound is a compound represented by any one of the following formulas 1-3 to 1-7, In formulas 1-3 to 1-7, R 1 represents a group represented by any one of the following formulas 2 to 4, R 19 ~R 22 Each independently represents a hydrogen atom, a halogen atom, -R a 、-OR b 、-CN、-SR c or -NR d R e , R 23 and R 24 Each independently represents -R a , R 25 and R 26 Each independently represents a hydrogen atom, a halogen atom or -R a , R a ~R e Each independently represents a hydrocarbon group, R 19 With R 20 、R 21 With R 22 、R 23 With R 24 or R 25 With R 26 They are optionally linked to form a monocyclic or polycyclic ring, and L represents an oxygen atom, a sulfur atom or -NR 10 -, R 10 represents a hydrogen atom, an alkyl group or an aryl group, R d1 ~R d4 、W 1 and W 2 Each independently represents an alkyl group optionally having a substituent, Za represents a counter ion for neutralizing the charge, In formula 2 to formula 4, R 20 、R 30 、R 41 and R 42 Each independently represents an alkyl group or an aryl group, Zb represents a counter ion for neutralizing the charge, and the wavy line represents a bonding site with L.

16. The on-press development type lithographic printing plate precursor according to claim 14, wherein The W 1 And the W 2 Each independently represents an alkyl group having a substituent, and the substituent is a group having at least -(OCH2CH2)-, a sulfo group, a salt of a sulfo group, a carboxyl group, or a salt of a carboxyl group.

17. The on-press development type lithographic printing plate precursor according to claim 1, wherein The image recording layer contains at least one selected from an electron-accepting polymerization initiator and an electron-donating polymerization initiator.

18. The on-press development type lithographic printing plate precursor according to claim 17, wherein The electron-accepting polymerization initiator includes a compound represented by the following formula (II): In formula (II), X represents a halogen atom, R 3 Represents an aryl group.

19. The on-press development type lithographic printing plate precursor according to claim 1, wherein The image recording layer contains a compound in which an electron-donating polymerization initiator and an electron-accepting polymerization initiator form an ion pair.

20. The on-press development type lithographic printing plate precursor according to claim 17, wherein The image recording layer contains an infrared absorber, and a value of a HOMO energy level of the infrared absorber minus the HOMO energy level of the electron donating polymerization initiator is 0.70 eV or less.

21. The on-press development type lithographic printing plate precursor according to claim 17, wherein The image recording layer contains an infrared absorber, and a value of a LUMO energy level of the electron-accepting polymerization initiator minus the LUMO energy level of the infrared absorber is 1.00 eV or less.

22. The on-press development type lithographic printing plate precursor according to claim 1, wherein The image recording layer contains a polymerizable compound having 7 or more polymerizable groups.

23. The on-press development type lithographic printing plate precursor according to claim 1, wherein The image recording layer contains a polymerizable compound having 10 or more polymerizable groups.

24. The on-press development type lithographic printing plate precursor according to claim 1, wherein The support body includes an aluminum plate and an aluminum anodic oxide film disposed on the aluminum plate. The anodic oxide film is located closer to the image recording layer than the aluminum plate. The anodic oxide film has micropores extending in 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.

25. The on-press development type lithographic printing plate precursor according to claim 24, wherein The micropores have a large-diameter pore portion and a small-diameter pore portion, wherein the large-diameter pore portion extends from the surface of the anodic oxide film to a depth of 10 nm to 1000 nm, and the small-diameter pore portion is connected to the bottom of the large-diameter pore portion and extends from the connection position with the large-diameter pore portion to a depth of 20 nm to 2000 nm. The average diameter of the large-diameter pores on the surface of the anodic oxide film is 15 nm to 100 nm. The average diameter of the small-diameter pores at the communication positions is 13 nm or less.

26. A method for producing a lithographic printing plate, comprising: A step of exposing the on-press developed lithographic printing plate precursor according to any one of claims 1 to 25 in an image-like manner; and A step of supplying at least one selected from printing ink and fountain solution to a printing press to remove the image recording layer in non-image areas.

27. A lithographic printing method comprising: A step of exposing the on-press developed lithographic printing plate precursor according to any one of claims 1 to 25 in an image-like manner; A process of supplying at least one selected from printing ink and fountain solution on a printing press to remove the image recording layer in non-image areas to produce a lithographic printing plate; and A step of performing printing using the obtained planographic printing plate.

Images