Positive type lithographic printing plate master and method for producing lithographic printing plates

Abstract

The present invention provides a positive-type lithographic printing plate master and a method for producing a lithographic printing plate that exhibits good development discrimination and good print durability and scratch resistance of the image portion of the resulting lithographic printing plate. [Solution] A positive-type lithographic printing plate master and a method for making a lithographic printing plate using the positive-type lithographic printing plate master, comprising a support and an image recording layer formed on the support, wherein the positive-type photosensitive resin composition contains a compound having at least one electron-withdrawing group and at least one phenolic hydroxyl group in one molecule, an alkali-soluble resin, and an infrared absorber, and the electron-withdrawing group is excluding sulfonyl groups.

Description

[Technical Field]

[0001] This disclosure relates to a positive-type lithographic printing plate master and a method for producing a lithographic printing plate. [Background technology]

[0002] Conventionally, various photosensitive compositions have been used as visible image forming materials and lithographic printing plate materials. In particular, the recent development of lasers in the field of lithographic printing has been remarkable, and solid-state lasers or semiconductor lasers with emission regions from near-infrared to infrared are readily available in high power and compact sizes. In the field of lithographic printing, these lasers are extremely useful as exposure light sources when directly producing plates from digital data such as computers. A positive-type lithographic printing plate for infrared lasers contains an alkali-soluble resin and an infrared absorbent (for example, an infrared absorbing dye, also known as an IR dye) that absorbs light and generates heat in its image-forming layer. Infrared absorbers, particularly IR dyes, act as developer inhibitors in unexposed areas, substantially reducing the solubility of the resin in the developer solution through interaction with the resin, thus forming the image area of ​​the lithographic printing plate. In exposed areas, the heat generated weakens the interaction between the IR dyes and the resin, causing them to dissolve in the developer solution and become non-image areas, thus forming the lithographic printing plate. In positive-type lithographic printing plates, the greater the difference in solubility in alkaline developer between the areas exposed and unexposed by the infrared laser, the better the image formation is considered to be. Conventional positive-type lithographic printing plates are known from those described in Patent Documents 1 and 2.

[0003] Patent Document 1 describes a lithographic printing plate having two image recording layers on a support, the first layer, i.e., the lower layer, containing a first resin that is water-insoluble and alkali-soluble, and the second layer, i.e., the upper layer, containing a second resin that is water-insoluble and alkali-soluble and contains phenolic hydroxyl groups, a photothermal converter, and a group of compounds with a molecular weight of 800 or less, each containing at least one substituent such as a carboxylic acid group or a phenolic hydroxyl group that suppresses the dissolution of the second resin, and in which there is said to be a large difference in developability between the exposed and unexposed areas.

[0004] Patent Document 2 describes a positive-type photosensitive composition containing an alkali-soluble organic polymer having phenolic hydroxyl groups, a photothermal conversion substance, at least one selected from a specific resin, and a dissolution inhibitor which is a low-molecular-weight compound having three phenolic hydroxyl groups, and which is said to have good alkali-developability in the unexposed areas. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2004-287001 [Patent Document 2] Patent No. 4081491 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] The performance requirements for a positive-type lithographic printing plate include good development discrimination, i.e., good difference in alkali developability between exposed and unexposed areas. Furthermore, the image portion of the resulting lithographic printing plate should exhibit good print resistance and scratch resistance. In positive-type lithographic printing plates, reducing the solubility of the image area in alkaline developer to improve print durability, i.e., to form a robust image area, and obtaining good alkaline developability in the non-image areas are conflicting properties, and it is considered difficult to achieve both simultaneously.

[0007] One embodiment of this disclosure aims to solve the problem of providing a positive-type lithographic printing plate master that exhibits good development discrimination and good print durability and scratch resistance of the image portion of the resulting lithographic printing plate. Another embodiment of this disclosure aims to solve the problem of providing a method for producing a lithographic printing plate that has good print durability and good developability of non-image areas. [Means for solving the problem]

[0008] The means for solving the above problems include the following embodiments. <1> A positive-type lithographic printing plate comprising a support and an image recording layer formed on the support, wherein the positive-type photosensitive resin composition contains a compound having at least one electron-withdrawing group and at least one phenolic hydroxyl group in one molecule, an alkali-soluble resin, and an infrared absorbent, and the electron-withdrawing group is excluding sulfonyl groups. <2> The above electron-withdrawing group is at least one selected from the group consisting of halogen atoms, trifluoromethyl groups, nitro groups, cyano groups, alkoxycarbonyl groups, acyloxy groups, amide groups, and alkylcarbonyl groups. <1> The original positive-type lithographic printing plate described above.

[0009] <3> The above-mentioned compound having at least one electron-withdrawing group and at least one phenolic hydroxyl group in one molecule is a compound having two or more phenolic hydroxyl groups in one molecule. <1> or <2> The original positive-type lithographic printing plate described above. <4> The above-mentioned compound having at least one electron-withdrawing group and at least one phenolic hydroxyl group in one molecule is a compound having three or more phenolic hydroxyl groups in one molecule. <1> or <2> The original positive-type lithographic printing plate described above. <5> The above electron-withdrawing group is an alkoxycarbonyl group or an alkylcarbonyl group. <1> ~ <3> A positive-type lithographic printing plate original described in one of the following. <6> The above-mentioned compound having at least one electron-withdrawing group and at least one phenolic hydroxyl group in a single molecule includes compounds selected from gallic acid ester compounds and compounds having multiple gallic acid ester moieties within the same molecule. <1> ~ <5> A positive-type lithographic printing plate original described in one of the following. <7> The compound having at least one electron-withdrawing group and at least one phenolic hydroxyl group in one molecule is a gallic acid ester compound. <1> ~ <6> A positive-type lithographic printing plate original described in one of the following.

[0010] <8> The above image recording layer is an image recording layer having a lower layer and an upper layer in that order from the support side, and at least one of the lower layer and the upper layer is made of the positive-type photosensitive resin composition. <1> ~ <7> A positive-type lithographic printing plate original described in one of the following. <9> The above support has an undercoat layer between it and the above image recording layer. <8> The original positive-type lithographic printing plate described above. <10> The lower layer is the positive-type photosensitive resin composition, and the alkali-soluble resin contained in the lower layer includes at least one selected from an acrylic resin having a sulfonamide group in its side chain, an acrylic resin having a phenolic hydroxyl group in its side chain, and a novolac resin. <8> or <9> The original positive-type lithographic printing plate described above. <11> The upper layer is made of the positive-type photosensitive resin composition, and the upper layer comprises an infrared absorbent and a water-insoluble and alkali-soluble resin, wherein the water-insoluble and alkali-soluble resin is at least one selected from the group consisting of polyamide resin, epoxy resin, polyacetal resin, acrylic resin, methacrylic resin, polystyrene resin, and novolac-type phenolic resin, and an interaction is formed between the polar groups of the water-insoluble and alkali-soluble resin and the infrared absorbent. <8> ~ <10> A positive-type lithographic printing plate original described in one of the following. <12> The above undercoat layer contains at least one selected from the group consisting of phosphonic acid having an amino group, organic phosphonic acid, organic phosphoric acid, organic phosphinic acid, amino acid, and hydrochloride salt of an amine having a hydroxyl group. <9> The original positive-type lithographic printing plate described above. <13> The above upper layer further comprises a polymer having a structural unit having an alkyl fluoride in its side chain. <8> ~ <12> A positive-type lithographic printing plate original described in one of the following. <14> At least one of the above upper layer and the above lower layer contains a polymer having a structural unit represented by the following formula (I): <8> ~ <12> A positive-type lithographic printing plate original described in one of the following.

[0011] [ka]

[0012] In formula (I), R 11 and R 12 Each of these independently represents a hydrogen atom or an alkyl group, R 13 represents a hydrogen atom or a monovalent substituent, L 11 and L 12 Each of these independently represents a single bond or a divalent linking group, and Rh represents a substituent containing two or more silicon atoms. <15> The upper layer includes a polymer having a structural unit represented by the above formula (I). <8> ~ <14> A positive-type lithographic printing plate original described in one of the following.

[0013] <16> <1> ~ <7> A method for producing a lithographic printing plate, comprising, in this order, an exposure step of image exposure of a positive type lithographic printing plate master described in any one of the above, and a development step of developing the exposed positive type lithographic printing plate master using an alkaline aqueous solution with a pH of 8.5 to 13.5. <17> <8> ~ <15> A method for producing a lithographic printing plate, comprising, in this order, an exposure step of image exposure of a positive type lithographic printing plate master described in any one of the above, and a development step of developing the exposed positive type lithographic printing plate master using an alkaline aqueous solution with a pH of 8.5 to 13.5. [Effects of the Invention]

[0014] According to one embodiment of the present disclosure, a positive-type lithographic printing plate is provided that exhibits good development discrimination and good print durability and scratch resistance of the image portion of the resulting lithographic printing plate. Another embodiment of the present disclosure provides a method for producing a lithographic printing plate that has good print resistance and good developability of non-image areas. [Modes for carrying out the invention]

[0015] The contents of this disclosure are described in detail below. The descriptions of the constituent elements described below may be based on representative embodiments of this disclosure, but this disclosure is not limited to such embodiments. In this disclosure, the "~" symbol indicating a numerical range is used to mean that the numbers before and after it are included as the lower and upper limits, respectively. Furthermore, in the notation of groups (atomic groups) in this disclosure, notations that do not specify whether they are substituted or unsubstituted include both those with and without substituents. For example, "alkyl group" includes not only alkyl groups without substituents (unsubstituted alkyl groups) but also alkyl groups with substituents (substituted alkyl groups). Furthermore, in this disclosure, "mass%" and "weight%" are synonymous, and "parts of mass" and "parts of weight" are synonymous. In this disclosure, the solid content of a composition refers to the mass excluding volatile components such as solvents. For example, low molecular weight monomers are included in the solid content even if they are liquid components. In this disclosure, the term "process" includes not only independent processes but also any process that cannot be clearly distinguished from other processes, as long as its intended purpose is achieved. In this disclosure, a preferred combination of embodiments is a more preferred embodiment.

[0016] In this disclosure, unless otherwise specified, the molecular weight of the polymer component is the weight-average molecular weight (Mw) or number-average molecular weight (Mn) on a polystyrene basis, measured by gel permeation chromatography (GPC) using tetrahydrofuran (THF) as the solvent.

[0017] (Positive lithographic printing plate original plate) The positive-type lithographic printing plate according to this disclosure comprises a support and an image recording layer formed on the support, wherein the positive-type photosensitive resin composition contains a compound having at least one electron-withdrawing group and at least one phenolic hydroxyl group in one molecule, an alkali-soluble resin, and an infrared absorber, and the electron-withdrawing group is excluding sulfonyl groups. The electron-withdrawing group is preferably at least one selected from the group consisting of a halogen atom, a trifluoromethyl group, a nitro group, a cyano group, an alkoxycarbonyl group, an acyloxy group, an amide group, and an alkylcarbonyl group. Examples of halogen atoms include chloro groups, bromo groups, fluoro groups, and iodo groups.

[0018] Hereinafter, in this disclosure, a compound having at least one electron-withdrawing group and at least one phenolic hydroxyl group in one molecule will also be referred to as a "specific compound." As a result of diligent research, the present inventors have found that, in the positive-type lithographic printing plate master according to this disclosure, the positive-type photosensitive resin composition contained in the image recording layer, when it contains the above-mentioned specific compound, exhibits good development discrimination, and the resulting lithographic printing plate has good print resistance and scratch resistance of the image portion. In this disclosure, "image recording layer made of a positive-type photosensitive resin composition" refers to a layer made of a dried positive-type photosensitive resin composition. The dried positive-type photosensitive resin composition may be obtained by drying means or by natural drying.

[0019] The detailed mechanism by which the above effects are achieved is unknown, but it is speculated to be as follows. The specific compound contained in the image recording layer of the positive-type lithographic printing plate according to this disclosure has a phenolic hydroxyl group in its molecule, and therefore forms a pseudo-crosslinked structure with the coexisting alkali-soluble resin through multi-point hydrogen bonding. For this reason, penetration and neutralization of the alkaline developer into the image recording layer are suppressed in the unexposed areas. On the other hand, in the exposed areas, when the above multi-point hydrogen bonding is released, the characteristic of low molecular acidity (pKa) due to the presence of electron-withdrawing groups and phenolic hydroxyl groups inherent in the specific compound is exhibited, and it functions as an alkali dissolution accelerator. Therefore, we believe that the specific compound exhibits a development-inhibiting effect in unexposed areas and a development-promoting effect in exposed areas, resulting in good development discrimination. Furthermore, we believe that the strong interaction between the phenolic hydroxyl groups and the alkali-soluble resin in the unexposed areas will result in a lithographic printing plate with excellent print resistance. This tendency is expected to be further enhanced by the large number of phenolic hydroxyl groups and the low molecular weight of the specific compound. Furthermore, the above mechanism is an estimation mechanism and does not limit this disclosure in any way.

[0020] The positive-type photosensitive resin composition that forms the image recording layer of the positive-type lithographic printing plate master according to this disclosure will also be simply referred to as the positive-type photosensitive resin composition of this disclosure. The details of each component contained in the positive-type photosensitive resin composition of this disclosure are described below.

[0021] <Specific compound> The positive-type photosensitive resin composition contains a compound having at least one electron-withdrawing group and at least one phenolic hydroxyl group in one molecule, i.e., a specific compound. The phenolic hydroxyl group can be any hydroxyl group bonded to an aromatic ring, for example, a hydroxyl group bonded to a benzene ring, or a hydroxyl group bonded to a naphthalene ring formed by the condensation of two or more aromatic rings.

[0022] From the viewpoint of achieving better development discrimination against alkaline developers and better print durability of the resulting image, the specific compound is preferably a compound having two or more phenolic hydroxyl groups in one molecule, and more preferably a compound having three or more phenolic hydroxyl groups in one molecule. A compound having two or more phenolic hydroxyl groups in one molecule means a compound having two or more hydroxyl groups directly bonded to a single aromatic ring.

[0023] The electron-withdrawing group possessed by a specific compound is preferably at least one selected from the group consisting of halogen atoms, trifluoromethyl groups, nitro groups, cyano groups, alkoxycarbonyl groups, acyloxy groups, amide groups, and alkylcarbonyl groups, excluding sulfonyl groups. These will be hereinafter referred to as specific electron-withdrawing groups. Here, examples of halogen atoms include chloro groups, bromo groups, fluoro groups, and iodo groups. The specific electron-withdrawing group is more preferably at least one selected from the group consisting of chloro group, bromo group, trifluoromethyl group, nitro group, cyano group, alkoxycarbonyl group, acyloxy group, amide group, and alkylcarbonyl group. Furthermore, among specific electron-withdrawing groups, it is even more preferable that the specific electron-withdrawing group in the specific compound relating to this disclosure be an alkoxycarbonyl group or an alkylcarbonyl group, from the viewpoint of more easily promoting alkali developability in the exposed area.

[0024] A specific compound may have only one electron-withdrawing group or two or more. When a molecule has two or more electron-withdrawing groups, the electron-withdrawing groups may be the same or different from each other. From the viewpoint of maintaining good solubility in the coating solvent used when preparing lithographic printing plates, it is preferable that the electron-withdrawing groups be different from each other.

[0025] Specific examples of particular compounds are listed below, but the specific compounds are not limited to these examples.

[0026] <Specific examples of specific compounds having one phenolic hydroxyl group and one electron-withdrawing group in the molecule: Specific compound group i>

[0027]

Chemical formula

[0028]

Chemical formula

[0029] <Specific examples of specific compounds having one phenolic hydroxyl group and two or more electron-withdrawing groups in the molecule: Specific compound group ii>

[0030]

Chemical formula

[0031] ​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​<Specific examples of specific compounds having two phenolic hydroxyl groups and one or more electron-withdrawing groups: Specific compound group iv>

[0036] [ka]

[0037] [ka]

[0038] <Specific examples of specific compounds having three or more phenolic hydroxyl groups and one or two electron-withdrawing groups: Specific compound group v>

[0039] [ka]

[0040] [ka]

[0041] The above specific examples all involve a single benzene ring or naphthalene ring having one or more phenolic hydroxyl groups and specific electron-withdrawing groups, respectively. However, the specific compound is not limited to the above, and may be a compound having multiple aromatic rings with phenolic hydroxyl groups and specific electron-withdrawing groups within its molecule. Having multiple aromatic rings with phenolic hydroxyl groups and specific electron-withdrawing groups within its molecule may result in stronger alkali-developability due to multi-point hydrogen bonding. The following are specific examples of specific compounds that have multiple aromatic rings containing phenolic hydroxyl groups and specific electron-withdrawing groups. <Specific examples of specific compounds having multiple aromatic rings with phenolic hydroxyl groups and specific electron-withdrawing groups: Specific compound group vi>

[0042] [ka]

[0043] [ka]

[0044] [ka]

[0045] Among the above, it is preferable that the specific compound includes a gallic acid ester compound belonging to specific compound group i, and a compound selected from compounds having multiple gallic acid ester moieties within the same molecule, and it is more preferable that it includes a gallic acid ester compound represented by the structure shown below.

[0046] [ka]

[0047] The positive-type photosensitive resin composition may contain one specific compound alone, or it may contain two or more specific compounds. From the viewpoint of achieving better development discrimination of the lithographic printing plate and better print durability of the resulting lithographic printing plate, the content of the specific compound is preferably 0.05% to 30% by mass, and more preferably 0.5% to 15% by mass, relative to the total solid content of the positive-type photosensitive resin composition.

[0048] <Alkali-soluble resin> The positive-type photosensitive resin composition contains an alkali-soluble resin. In this disclosure, "alkali-soluble" means that 0.01 g of the resin dissolves in 5 g of a sodium hydroxide aqueous solution at 30°C and pH 13.0 within 200 seconds. Dissolution means that no residual dissolved material can be visually confirmed. Examples of alkali-soluble resins include acrylic resins, novolac resins, polyureas, polyurethanes, or polycarbonates. From the viewpoint of further improving development discrimination and print durability, acrylic resin or novolac resin is preferred. The following describes preferred embodiments of the alkali-soluble resin relating to this disclosure.

[0049] [Acrylic resin] As the alkali-soluble resin, for example, any compound known in the field of positive-type lithographic printing plates can be used without particular limitation, but the water-insoluble and alkali-soluble resin described in paragraphs 0025 to 0062 of Japanese Patent Application Publication No. 2008-151929 is preferred. Among these, acrylic resins having sulfonamide groups in the side chain, or acrylic resins having phenolic hydroxyl groups in the side chain, are preferred.

[0050] -Acrylic resin having sulfonamide groups in its side chains- Examples of acrylic resins having sulfonamide groups in their side chains include copolymers containing monomer units formed from monomers having sulfonamide groups. Examples of monomers having a sulfonamide group include, but are not limited to, (meth)acrylamide compounds having a sulfonamide group, (meth)acrylic acid ester compounds having a sulfonamide group, and styrene compounds having a sulfonamide group. Specifically, examples include N-(p-toluenesulfonyl)acrylamide and N-(p-toluenesulfonyl)methacrylamide. The copolymer described above may further contain monomer units formed by other monomers, and examples of other monomers include known (meth)acrylic acid ester compounds, (meth)acrylamide compounds, acrylonitrile compounds, styrene compounds, etc., and monomers described in paragraphs 0034 to 0035 of Japanese Patent Application Publication No. 2008-151929 can also be suitably used. In this disclosure, the term "(meth)acrylic acid ester compound, etc." means acrylic acid ester compound or methacrylic acid ester compound, etc.

[0051] -Acrylic resin having phenolic hydroxyl groups in its side chains- Examples of acrylic resins having phenolic hydroxyl groups in their side chains include copolymers containing monomer units formed from monomers having phenolic hydroxyl groups. The monomer having a phenolic hydroxyl group is not particularly limited, but examples include (meth)acrylamide compounds, (meth)acrylic acid ester compounds, or hydroxystyrene compounds having a phenolic hydroxyl group. Specifically, N-(2-hydroxyphenyl)acrylamide, N-(3-hydroxyphenyl)acrylamide, N-(4-hydroxyphenyl)acrylamide, N-(2-hydroxyphenyl)methacrylamide, N-(3-hydroxyphenyl)methacrylamide, N-(4-hydroxyphenyl)methacrylamide, o-hydroxyphenyl acrylate, m-hydroxyphenyl acrylate, p-hydroxyphenyl acrylate, o-hydroxyphenyl methacrylate, m-hydroxyphenyl methacrylate, p-hydroxyphenyl methacrylate, o-hydroxystyrene, m-hydroxystyrene, p-hydroxystyrene, 2-(2-hydroxyphenyl)ethyl acrylate, 2-(3-hydroxyphenyl)ethyl acrylate, 2-(4-hydroxyphenyl)ethyl acrylate, 2-(2-hydroxyphenyl)ethyl methacrylate, 2-(3-hydroxyphenyl)ethyl methacrylate, 2-(4-hydroxyphenyl)ethyl methacrylate, etc. can be suitably used.

[0052] The copolymers of the acrylic resin having a sulfonamide group in the side chain and the acrylic resin having a phenolic hydroxyl group in the side chain may further contain monomer units formed by other monomers. Examples of other monomers include known (meth)acrylic acid ester compounds, acrylonitrile compounds, allyl cyanide compounds, styrene compounds, etc. The monomers described in paragraphs 0034 to 0035 of Japanese Patent Application Publication No. 2008-151929 can also be suitably used.

[0053] The weight-average molecular weight of the acrylic resin having a sulfonamide group in its side chain or the acrylic resin having a phenolic hydroxyl group in its side chain is preferably more than 5,000 and 300,000 or less, and more preferably between 10,000 and 200,000. Specific examples of acrylic resins having sulfonamide groups in their side chains or phenolic hydroxyl groups in their side chains are shown below, but are not limited to these examples. In the specific examples below, the subscripts in parentheses indicating monomer units represent the content (mol%) of each monomer unit, where Me represents a methyl group and Ph represents a phenyl group.

[0054] [ka]

[0055] [Polyurea, polyurethane, polycarbonate] Furthermore, polyurea, polyurethane, or polycarbonate can also be suitably used as alkali-soluble resins. Polyurea, polyurethane, or polycarbonate is preferably found to have acidic groups, and more preferably to have sulfonamide groups in its main chain from the viewpoint of print resistance and developability. Polyurea, polyurethane, or polycarbonate is preferably provided with other acidic groups in its side chains. Preferred acidic groups in the side chains are phenolic hydroxyl groups, sulfonamide groups, or carboxyl groups. Examples of these alkali-soluble resins include the compounds described in paragraphs 0083 to 0114 of Japanese Patent Publication No. 2018-165797, and these descriptions can be referenced in this disclosure.

[0056] [Novolac resin] Novolac resins are also preferred as alkali-soluble resins. Preferred novolac resins that can be used in the positive-type photosensitive resin composition according to this disclosure include phenol-formaldehyde resin, m-cresol-formaldehyde resin, p-cresol-formaldehyde resin, m- / p-mixed cresol-formaldehyde resin, phenol / cresol (m-, p-, or m- / p-mixed) mixed formaldehyde resin, and pyrogallolacetone resin. Furthermore, as described in U.S. Patent No. 4,123,279, examples include condensed polymers of phenol and formaldehyde having C3-C8 alkyl groups as substituents, such as t-butylphenolformaldehyde resin and octylphenolformaldehyde resin. The weight-average molecular weight (Mw) is preferably 500 or more, more preferably 1,000 to 700,000. The number-average molecular weight (Mn) is also preferably 500 or more, more preferably 750 to 650,000. The degree of dispersion (weight-average molecular weight / number-average molecular weight) is preferably 1.1 to 10.

[0057] As for the alkali-soluble resin, there are no particular restrictions as long as it has the property of dissolving when it comes into contact with an alkaline developer. However, it is preferable that at least one of the main chain and side chains in the polymer has an acidic functional group such as a sulfonic acid group, a phosphate group, a sulfonamide group, or an active imide group. Examples include resins containing 10 mol% or more of a monomer having such an acidic functional group that imparts alkali solubility, and resins containing 20 mol% or more are more preferable. If the copolymer component of the monomer that imparts alkali solubility is 10 mol% or more, sufficient alkali solubility can be obtained, and the developability is also excellent.

[0058] The alkali-soluble resin is preferably one with a weight-average molecular weight of 2,000 or more and a number-average molecular weight of 500 or more, and more preferably one with a weight-average molecular weight exceeding 5,000 and 300,000 or less, and a number-average molecular weight of 800 to 250,000. Furthermore, the degree of dispersion (weight-average molecular weight / number-average molecular weight) of the other alkali-soluble resins is preferably 1.1 to 10.

[0059] -Content- The alkali-soluble resin in the positive-type photosensitive resin composition according to this disclosure may be used alone or in combination of two or more types. Furthermore, the alkali-soluble resin content in this disclosure is preferably 10% to 90% by mass, more preferably 20% to 80% by mass, and even more preferably 30% to 80% by mass, based on the total solid content of the positive-type photosensitive resin composition.

[0060] <Infrared absorbent> The positive-type photosensitive resin composition contains an infrared absorbent. As an infrared absorber, there are no particular restrictions as long as it is a dye that absorbs infrared light and generates heat; various dyes known as infrared absorbers can be used. Examples of infrared absorbers that can be used in this disclosure include those described in paragraphs 0075 to 0085 of International Publication No. 2016 / 047392.

[0061] Among these dyes, particularly preferred are cyanine dyes, phthalocyanine dyes, oxonol dyes, squarylium dyes, pyryllium salts, thiopyrillium dyes, and nickel thiolate complexes. Furthermore, the cyanine dye represented by the following formula (a) is most preferred because, when used in the upper layer of the positive type lithographic printing plate master according to this disclosure, it exhibits good release of the dissolution inhibition effect due to exposure, as well as excellent stability and economic efficiency.

[0062] [ka]

[0063] In formula (a), X 1 represents a hydrogen atom, a halogen atom, a diarylamino group, -X 2 -L 1 or a group represented by the following formula (b). X 2 represents an oxygen atom or a sulfur atom, and L 1 represents a hydrocarbon group having 1 to 12 carbon atoms, an aromatic ring having a heteroatom, or a hydrocarbon group having 1 to 12 carbon atoms containing a heteroatom. Here, the heteroatom represents N, S, O, a halogen atom, or Se.

[0064]

Chemical formula

[0065] In formula (b), Xa - is defined in the same way as Za - described later, and R a represents a substituent selected from the group consisting of a hydrogen atom, an alkyl group, an aryl group, a substituted or unsubstituted amino group, and a halogen atom.

[0066] R 21 and R 22 each independently represent a hydrocarbon group having 1 to 12 carbon atoms. From the viewpoint of the storage stability of the positive-type lithographic printing plate precursor, R 21 and R 22 are preferably hydrocarbon groups having 2 or more carbon atoms. Furthermore, it is particularly preferable that R 21 and R 22 are bonded to each other to form a 5-membered ring or a 6-membered ring.

[0067] Ar 1 , Ar 2Each of these groups may be the same or different, and may have substituents. Preferred aromatic hydrocarbon groups include benzene rings and naphthalene rings. Preferred substituents include hydrocarbon groups having 1 to 12 carbon atoms, halogen atoms, and alkoxy groups having 1 to 12 carbon atoms. Y 11 , Y 12 These may be the same or different, and each represents a sulfur atom or a dialkylmethylene group having 3 to 12 carbon atoms. 23 and R 24 Each of these groups may be the same or different, and may have substituents, representing a hydrocarbon group having 1 to 20 carbon atoms. Preferred substituents include alkoxy groups, carboxyl groups, and sulfo groups having 1 to 12 carbon atoms. R 25 , R 26 , R 27 and R 28 These may be the same or different, and represent a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms. Due to the availability of raw materials, a hydrogen atom is preferred. Also, Za - represents a counter anion. However, if the cyanine dye represented by formula (a) has an anionic substituent in its structure and charge neutralization is not required, then Za - It is not necessary. Preferred Za - From the viewpoint of storage stability of positive-type lithographic printing plates, these are halide ions, perchlorate ions, tetrafluoroborate ions, hexafluorophosphate ions, and sulfonate ions, and are particularly preferred to be perchlorate ions, hexafluorophosphate ions, and arylsulfonate ions.

[0068] Specific examples of cyanine dyes represented by formula (a) that can be preferably used include those described in paragraphs 0017-0019 of Japanese Patent Publication No. 2001-133969, paragraphs 0012-0038 of Japanese Patent Publication No. 2002-40638, and paragraphs 0012-0023 of Japanese Patent Publication No. 2002-23360. Particularly preferred as an infrared absorber is the cyanine dye A shown below.

[0069] [ka]

[0070] The content of the infrared absorber in the positive-type photosensitive resin composition is preferably 0.01% to 50% by mass, more preferably 0.1% to 30% by mass, and particularly preferably 1.0% to 30% by mass, based on the total solid content of the positive-type photosensitive resin composition. When the content is 0.01% by mass or more, high sensitivity is achieved, and when it is 50% by mass or less, the resulting layer has good uniformity and excellent durability.

[0071] <Acid Generator> Positive-type photosensitive resin compositions preferably contain an acid generator from the viewpoint of improving sensitivity to exposure. In this disclosure, "acid generator" refers to a compound that generates acid in response to light or heat, and specifically a compound that decomposes and generates acid upon irradiation with infrared radiation or heating to 100°C or higher. Preferably, the generated acid is a strong acid with a pKa of 2 or less, such as sulfonic acid or hydrochloric acid. The acid generated by this acid generator increases the permeability of the developer to the exposed area, thereby improving the solubility of the exposed area in an alkaline aqueous solution.

[0072] Examples of acid generators suitably used in the positive-type photosensitive resin composition relating to this disclosure include the acid generators described in paragraphs 0116 to 0130 of International Publication No. 2016 / 047392.

[0073] In particular, from the viewpoint of sensitivity and stability, it is preferable to use onium salt compounds as acid generators. Onium salt compounds will be described below. Suitable onium salt compounds for use in the positive-type photosensitive resin composition according to this disclosure include compounds known to decompose upon infrared exposure and due to the thermal energy generated from the infrared absorber upon exposure, thereby generating acid. Suitable onium salt compounds for the positive-type photosensitive resin composition according to this disclosure include, from the viewpoint of sensitivity, those having known thermal polymerization initiators or bonds with low bond dissociation energy, and having the onium salt structure described below. Suitable onium salts for use in the positive-type photosensitive resin composition according to this disclosure include known diazonium salts, iodonium salts, sulfonium salts, ammonium salts, pyridinium salts, azinium salts, etc., among which triarylsulfonium or diaryliodonium sulfonates, carboxylates, BF4 - PF6 - ClO4 - These are preferable. Examples of onium salts that can be used as acid generators in the positive-type photosensitive resin composition according to this disclosure include onium salts represented by the following formulas (III) to (V).

[0074] [ka]

[0075] In formula (III), Ar 11 and Ar 12 Each of these independently represents an aryl group having 6 to 20 carbon atoms, which may have substituents. Preferred substituents when this aryl group has substituents include halogen atoms, nitro groups, alkyl groups having 1 to 12 carbon atoms, alkoxy groups having 1 to 12 carbon atoms, or aryloxy groups having 1 to 12 carbon atoms. 11- These are halide ions, perchlorate ions, tetrafluoroborate ions, and hexafluorophosphates. This represents a counterion selected from the group consisting of phosphate ions, sulfonate ions, and sulfonate ions having a fluorine atom, such as perfluoroalkyl sulfonate ions, and is preferably a perchlorate ion, hexafluorophosphate ion, aryl sulfonate ion, and perfluoroalkyl sulfonic acid. In formula (IV), Ar 21 represents an aryl group having 6 to 20 carbon atoms, which may have substituents. Preferred substituents include halogen atoms, nitro groups, alkyl groups having 1 to 12 carbon atoms, alkoxy groups having 1 to 12 carbon atoms, aryloxy groups having 1 to 12 carbon atoms, alkylamino groups having 1 to 12 carbon atoms, dialkylamino groups having 2 to 12 carbon atoms, arylamino groups having 6 to 12 carbon atoms, or diarylamino groups (each independently having 6 to 12 carbon atoms in the aryl group). 21- is Z 11- It represents a counter ion that is synonymous with [the other ion]. In formula (V), R 31 , R 32 and R 33 Each of these may be the same or different, and may have substituents, representing a hydrocarbon group having 1 to 20 carbon atoms. Preferred substituents include halogen atoms, nitro groups, alkyl groups having 1 to 12 carbon atoms, alkoxy groups having 1 to 12 carbon atoms, or aryloxy groups having 1 to 12 carbon atoms. 31- is Z 11- It represents a counter ion that is synonymous with [the other ion].

[0076] Specific examples of onium salts that can be suitably used in the positive-type photosensitive resin composition relating to this disclosure are the same as the compounds described in paragraphs 0121 to 0124 of International Publication No. 2016 / 047392.

[0077] Furthermore, as another example of the compounds represented by formulas (III) to (V) above, the compounds described as examples of radical polymerization initiators in paragraphs 0036 to 0045 of Japanese Patent Application Publication No. 2008-195018 can be suitably used as acid generators in the positive-type photosensitive resin composition according to this disclosure.

[0078] More preferred examples of acid generators that can be used in the positive-type photosensitive resin composition according to this disclosure include compounds represented by the following formulas PAG-1 to PAG-5. In formulas PAG-1 to PAG-5, Me represents a methyl group.

[0079] [ka]

[0080] When these acid generators are included in the positive-type photosensitive resin composition according to this disclosure, these compounds may be used individually or in combination of two or more. The preferred content of the acid generator is in the range of 0.01% to 50% by mass, preferably 0.1% to 40% by mass, and more preferably 0.5% to 30% by mass, relative to the total solid content of the positive-type photosensitive resin composition. Within this content range, an improvement in sensitivity, which is the effect of adding the acid generator, is observed, and the formation of residual film in non-image areas is suppressed.

[0081] <Acid growth agent> The positive-type photosensitive resin composition may contain an acid proliferator. In this disclosure, the acid proliferator is a compound substituted with a relatively strong acid residue, which readily desorbs in the presence of an acid catalyst to generate new acid. That is, it decomposes through an acid-catalyzed reaction, generating acid again. One or more acids are added in each reaction, and the acid concentration increases exponentially as the reaction progresses, dramatically improving sensitivity. The strength of the generated acid is preferably such that its acid dissociation constant (pKa) is 3 or less, and more preferably 2 or less. An acid dissociation constant of 3 or less makes it easier to trigger an elimination reaction by an acid catalyst. Acids used in such acid catalysts include dichloroacetic acid, trichloroacetic acid, methanesulfonic acid, ethanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, naphthalenesulfonic acid, and phenylsulfonic acid.

[0082] The available acid growth agents are similar to those described in paragraphs 0133 to 0135 of International Publication No. 2016 / 047392.

[0083] The content of these acid-proliferating agents is in the range of 0.01% to 20% by mass, preferably 0.01% to 10% by mass, and more preferably 0.1% to 5% by mass, based on the total mass of the positive-type photosensitive resin composition. When the content of the acid-proliferating agent is within the above range, the effect of adding the acid-proliferating agent is sufficiently obtained, improving sensitivity to exposure and suppressing the decrease in film strength of the image area.

[0084] <Other additives> The positive-type photosensitive resin composition may also contain other additives such as developer accelerators, surfactants, burn-out agents / colorants, plasticizers, and waxes. These can be the same as those described in paragraphs 0138 to 0142 of International Publication No. 2016 / 047392.

[0085] <Composition ratio of each component> The content of the specific compound is preferably 0.05% to 30% by mass relative to the total solid content of the positive-type photosensitive resin composition according to this disclosure, the content of the alkali-soluble resin is preferably 10% to 90% by mass, the content of the infrared absorber is preferably 0.01% to 50% by mass, the content of the acid generator is preferably 0% to 50% by mass, the content of the acid booster is preferably 0% to 20% by mass, the content of the development accelerator is preferably 0% to 20% by mass, the content of the surfactant is preferably 0% to 5% by mass, the content of the burnishing agent / coloring agent is preferably 0% to 10% by mass, the content of the plasticizer is preferably 0% to 10% by mass, and the content of the waxing agent is preferably 0% to 10% by mass.

[0086] The positive-type photosensitive resin composition according to this disclosure is capable of recording with high sensitivity, has excellent image-forming properties, and exhibits good durability of the formed image portion. Therefore, the positive-type lithographic printing plate master according to this disclosure, which has an image recording layer made of the positive-type photosensitive resin composition, can produce a lithographic printing plate with excellent print resistance.

[0087] (Composition of the original plate for positive-type lithographic printing) The positive-type lithographic printing plate master according to this disclosure has an image recording layer containing the positive-type photosensitive resin composition described above on a support having a hydrophilic surface. The image recording layer may be a single layer, or it may be a multilayered image recording layer having a lower layer and an upper layer near the support. Furthermore, the image recording layer has an image recording layer having a lower layer and an upper layer in that order from the support side, and it is preferable that at least one of the lower layer and the upper layer is a positive-type photosensitive resin composition, and it is more preferable that either the lower layer or the upper layer is a positive-type photosensitive resin composition.

[0088] The image recording layer of the positive-type lithographic printing plate master according to this disclosure can be formed by dissolving each component of the positive-type photosensitive resin composition described above in a solvent, applying it to a suitable support, and curing it. Examples of solvents used here include, but are not limited to, ethylene dichloride, cyclohexanone, methyl ethyl ketone, methanol, ethanol, propanol, ethylene glycol monomethyl ether, 1-methoxy-2-propanol, 2-methoxyethyl acetate, 1-methoxy-2-propyl acetate, dimethoxyethane, methyl lactate, ethyl lactate, N,N-dimethylacetamide, N,N-dimethylformamide, tetramethylurea, N-methylpyrrolidone, dimethyl sulfoxide, sulfolane, γ-butyrolactone, and toluene. These solvents may be used individually or in combination.

[0089] <Formation of lower and upper layers> Furthermore, the positive type lithographic printing plate master according to this disclosure is preferably a positive type lithographic printing plate master having an image recording layer on a support having a lower layer and an upper layer in that order (hereinafter also referred to as a "two-layer image recording layer"). In principle, it is preferable to form the lower and upper layers as two separate layers. Methods for separating and forming the two layers include, for example, utilizing the difference in solvent solubility between the components in the lower layer and the components in the upper layer, or applying the upper layer and then rapidly drying and removing the solvent. The latter method is preferable because it allows for even better separation between the layers. The following details these methods, but these are not the only methods for separating and applying the two layers.

[0090] One method that utilizes the difference in solvent solubility between the components in the lower layer and the components in the upper layer involves using a solvent system in which none of the components in the lower layer are soluble when applying the upper layer coating solution. This makes it possible to clearly separate each layer into a coating film even when applying two layers. For example, a component insoluble in solvents such as methyl ethyl ketone or 1-methoxy-2-propanol, which dissolves the alkali-soluble resin component of the upper layer, is selected as the lower layer component. The lower layer is then coated and dried using the solvent system that dissolves the lower layer component, and then the upper layer, mainly composed of alkali-soluble resin, is dissolved with methyl ethyl ketone or 1-methoxy-2-propanol, coated, and dried, thereby enabling the creation of a two-layer coating.

[0091] Next, to dry the solvent very quickly after applying the second layer (upper layer), this can be achieved by blowing high-pressure air from a slit nozzle positioned almost perpendicular to the direction of the web's movement, by supplying thermal energy as conductive heat from the underside of the web through a roll (heating roll) supplied with a heating medium such as steam, or by combining these methods.

[0092] The specific compound is preferably contained in at least one of the lower and upper layers, more preferably in the upper layer only, and particularly preferably in the lower layer only, or in both the upper and lower layers.

[0093] The amount of the lower layer component applied to the support of the positive-type lithographic printing plate master according to this disclosure after drying is 0.5 g / m². 2 ~4.0g / m 2It is preferable that it be within the range of 0.6 g / m 2 ~2.5g / m 2 It is more preferable to be within the range of 0.5 g / m 2 If the above is true, it will have excellent print durability and 4.0 g / m² 2 The following conditions result in superior image reproduction and sensitivity. Furthermore, the amount of the upper layer component applied after drying is 0.05 g / m². 2 ~1.0g / m 2 It is preferable that it be within the range of 0.08 g / m 2 ~0.7g / m 2 It is more preferable that the range be 0.05 g / m 2 The above results in excellent development latitude and scratch resistance, and the 1.0g / m² 2 The following conditions result in superior sensitivity. The combined coating amount after drying of the lower and upper layers is 0.6 g / m². 2 ~4.0g / m 2 It is preferable that it be within the range of 0.7 g / m 2 ~2.5g / m 2 It is more preferable to be within the range of 0.6 g / m². 2 If the above is true, it will have excellent print durability and 4.0 g / m² 2 The following conditions result in superior image reproduction and sensitivity.

[0094] <Upper layer> The upper layer of the two-layer image recording layer in this disclosure may be a layer made of the positive-type photosensitive resin composition according to this disclosure, but it is preferable that the layer be made of a resin composition other than the positive-type photosensitive resin composition according to this disclosure. In this disclosure, the upper layer of the two-layer image recording layer is preferably an infrared-sensitive positive-type image recording layer whose solubility in an alkaline aqueous solution is improved by heat. There are no particular limitations on the mechanism by which the solubility in the alkaline aqueous solution is improved by heat in the upper layer; any binder resin that improves the solubility of the heated region can be used. Heat used for image formation includes the heat generated when the lower layer containing the infrared absorber is exposed to light. Examples of upper layers whose solubility in alkaline aqueous solutions is improved by heat include, for example, a layer containing an alkali-soluble resin having hydrogen bonding properties such as novolac or urethane, a layer containing a water-insoluble and alkali-soluble resin and a compound that inhibits dissolution, and a layer containing an ablationable compound.

[0095] More specifically, the upper layer comprises an infrared absorbent and a water-insoluble and alkali-soluble resin, wherein the water-insoluble and alkali-soluble resin is at least one selected from the group consisting of polyamide resin, epoxy resin, polyacetal resin, acrylic resin, methacrylic resin, polystyrene resin, and novolac-type phenolic resin, and it is preferable that an interaction is formed between the polar groups of the water-insoluble and alkali-soluble resin and the infrared absorbent. In the upper layer, the above interaction is formed, which prevents a decrease in the developability of the exposed area and suppresses the occurrence of unwanted ablation of the upper layer surface due to exposure.

[0096] Furthermore, by adding an infrared absorbent to the upper layer, the heat generated in the upper layer can also be utilized for image formation. Preferred configurations for the upper layer containing the infrared absorbent include, for example, a layer containing an infrared absorbent, a water-insoluble and alkali-soluble resin, and a compound that inhibits dissolution, or a layer containing an infrared absorbent, a water-insoluble and alkali-soluble resin, and an acid generator.

[0097] [Water-insoluble and alkali-soluble resin] In this disclosure, the upper layer of the two-layer image recording layer preferably contains a water-insoluble and alkali-soluble resin. By containing a water-insoluble and alkali-soluble resin, an interaction is formed between the infrared absorber and the polar groups of the water-insoluble and alkali-soluble resin, forming a positive-type photosensitive layer. Common water-insoluble and alkali-soluble resins are described in detail below, but among them, polyamide resins, epoxy resins, polyacetal resins, acrylic resins, methacrylic resins, polystyrene resins, novolac-type phenolic resins, and the like are particularly preferred. The above-mentioned water-insoluble and alkali-soluble resin is not particularly limited as long as it has the property of dissolving when in contact with an alkaline developer, but it is preferably a homopolymer, copolymer thereof, or mixture thereof, in which an acidic group is contained in at least one of the main chain and side chains in the polymer. Such water-insoluble and alkali-soluble resins having acidic groups preferably have functional groups such as phenolic hydroxyl groups, carboxyl groups, sulfonic acid groups, phosphoric acid groups, sulfonamide groups, and active imide groups. Therefore, such resins can be suitably produced by copolymerizing a monomer mixture containing one or more ethylenically unsaturated monomers having the above-mentioned functional groups. In addition to acrylic acid and methacrylic acid, compounds represented by the following formula and mixtures thereof are preferably exemplified as ethylenically unsaturated monomers having the above-mentioned functional groups. In the following formula, R 40 represents a hydrogen atom or a methyl group.

[0098] [ka]

[0099] The above-mentioned water-insoluble and alkali-soluble resin is preferably a polymer compound obtained by copolymerizing the above-mentioned polymerizable monomer with other polymerizable monomers. In this case, the copolymerization ratio preferably contains 10 mol% or more of a monomer that imparts alkali solubility, such as a monomer having functional groups such as a phenolic hydroxyl group, a carboxyl group, a sulfonic acid group, a phosphate group, a sulfonamide group, or an active imide group, and more preferably contains 20 mol% or more. When the copolymerization component of the monomer that imparts alkali solubility is 10 mol% or more, sufficient alkali solubility is obtained, and the developability is excellent.

[0100] Other polymerizable monomers that can be used include the following compounds: Alkyl acrylates and alkyl methacrylates such as methyl acrylate, ethyl acrylate, propyl acrylate, benzyl acrylate, methyl methacrylate, ethyl methacrylate, cyclohexyl methacrylate, and benzyl methacrylate. Acrylic acid esters and methacrylic acid esters having aliphatic hydroxyl groups such as 2-hydroxyethyl acrylate or 2-hydroxyethyl methacrylate. Acrylamides or methacrylamides such as acrylamide, methacrylamide, N-methylacrylamide, N-ethylacrylamide, and N-phenylacrylamide. Vinyl esters such as vinyl acetate, vinyl chloroacetate, vinyl butyrate, and vinyl benzoate. Styrenees such as styrene, α-methylstyrene, methylstyrene, and chloromethylstyrene. Other nitrogen atom-containing monomers such as N-vinylpyrrolidone, N-vinylpyridine, acrylonitrile, and methacrylonitrile. Maleimides such as N-methylmaleimide, N-ethylmaleimide, N-propylmaleimide, N-butylmaleimide, N-phenylmaleimide, N-2-methylphenylmaleimide, N-2,6-diethylphenylmaleimide, N-2-chlorophenylmaleimide, N-cyclohexylmaleimide, N-laurylmaleimide, and N-hydroxyphenylmaleimide. Of these other ethylenically unsaturated monomers, (meth)acrylic acid esters, (meth)acrylamides, maleimides, and (meth)acrylonitriles are preferred for use.

[0101] Furthermore, as an alkali-soluble resin, novolac resins, which are listed as other alkali-soluble resins listed as optional components of the positive-type photosensitive resin composition according to this disclosure, are also preferred. Furthermore, the above-mentioned water-insoluble and alkali-soluble resin can also be used in the positive-type photosensitive resin composition according to this disclosure.

[0102] Furthermore, other resins can be used in combination in the upper layer of the two-layer image recording layer in this disclosure, as long as the effect of the positive-type lithographic printing plate original plate according to this disclosure is not impaired. The upper layer itself is required to exhibit alkali solubility, especially in the non-image area, so it is necessary to select a resin that does not impair this property. From this viewpoint, resins that can be used in combination include water-insoluble and alkali-soluble resins. General water-insoluble and alkali-soluble resins will be described in detail below, but among them, polyamide resins, epoxy resins, polyacetal resins, acrylic resins, methacrylic resins, polystyrene resins, novolac-type phenolic resins, etc. can be preferably mentioned. Furthermore, the amount to be mixed is preferably 50% by mass or less relative to the water-insoluble and alkali-soluble resin mentioned above.

[0103] The above water-insoluble and alkali-soluble resin preferably has a weight-average molecular weight of 2,000 or more and a number-average molecular weight of 500 or more, and more preferably has a weight-average molecular weight of 5,000 to 300,000 and a number-average molecular weight of 800 to 250,000. Furthermore, the degree of dispersion (weight-average molecular weight / number-average molecular weight) of the above alkali-soluble resin is preferably 1.1 to 10. The above-mentioned water-insoluble and alkali-soluble resins may be used individually or in combination of two or more types. The content of the water-insoluble and alkali-soluble resin described above is preferably 2.0% to 99.5% by mass, more preferably 10.0% to 99.0% by mass, and even more preferably 20.0% to 90.0% by mass, based on the total solid content mass of the upper layer of the two-layer image recording layer in this disclosure. When the alkali-soluble resin content is 2.0% by mass or more, the durability of the image recording layer (photosensitive layer) is excellent, and when it is 99.5% by mass or less, both sensitivity and durability are excellent.

[0104] [Infrared absorber] The upper layer described above may contain an infrared absorbent. As an infrared absorbent, there are no particular restrictions as long as it is a dye that absorbs infrared light and generates heat, and the infrared absorbent used in the positive-type photosensitive resin composition according to this disclosure, as described above, can be used in the same way. A particularly preferred dye is the cyanine dye represented by the above formula (a).

[0105] By including an infrared absorbent in the upper layer, a positive-type lithographic printing plate with excellent image-forming properties can be obtained. The infrared absorbent content in the upper layer is preferably 0.01% to 50% by mass, more preferably 0.1% to 30% by mass, and particularly preferably 1.0% to 10% by mass, relative to the total solid content of the upper layer. A content of 0.01% by mass or more improves sensitivity, while a content of 50% by mass or less results in good layer uniformity and excellent layer durability.

[0106] [Surfactants] The upper layer described above preferably contains a surfactant from the viewpoint of improving the surface quality of the coating film. Examples of surfactants include nonionic surfactants, anionic surfactants, cationic surfactants, amphoteric surfactants, and fluorinated surfactants. Surfactants may be used individually or in combination of two or more types.

[0107] The nonionic surfactants used in this disclosure are not particularly limited and conventionally known surfactants can be used. Examples include polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene polystyrenephenyl ethers, polyoxyethylene polyoxypropylene alkyl ethers, glycerin fatty acid partial esters, sorbitan fatty acid partial esters, pentaerythritol fatty acid partial esters, propylene glycol mono fatty acid esters, sucrose fatty acid partial esters, polyoxyethylene sorbitan fatty acid partial esters, polyoxyethylene sorbitol fatty acid partial esters, polyethylene glycol fatty acid esters, polyglycerin fatty acid partial esters, polyoxyethylene castor oils, polyoxyethylene glycerin fatty acid partial esters, fatty acid diethanolamides, N,N-bis-2-hydroxyalkylamines, polyoxyethylene alkylamines, triethanolamine fatty acid esters, trialkylamine oxides, polyethylene glycol, and copolymers of polyethylene glycol and polypropylene glycol.

[0108] The anionic surfactants used in this disclosure are not particularly limited and conventionally known surfactants can be used. For example, fatty acid salts, abietins, hydroxyalkanesulfons, alkanesulfons, dialkylsulfosucric acid salts, linear alkylbenzenesulfons, branched alkylbenzenesulfons, alkylnaphthalenesulfons, alkylphenoxypolyoxyethylenepropylsulfons, polyoxyethylene alkylsulfophenyl ether salts, sodium N-methyl-N-oleyl taurate, disodium N-alkylsulfosuccinate monoamide, petroleum sulfons, sulfated beef tallow, sulfated fatty acid alkyl esters, and Examples include chloryl sulfate salts, polyoxyethylene alkyl ether sulfate salts, fatty acid monoglyceride sulfate salts, polyoxyethylene alkylphenyl ether sulfate salts, polyoxyethylene styrylphenyl ether sulfate salts, alkyl phosphate salts, polyoxyethylene alkyl ether phosphate salts, polyoxyethylene alkylphenyl ether phosphate salts, partially saponified styrene / maleic anhydride copolymers, partially saponified olefin / maleic anhydride copolymers, and naphthalene sulfonate formalin condensates.

[0109] The cationic surfactants used in this disclosure are not particularly limited, and conventionally known surfactants can be used. Examples include alkylamine salts, quaternary ammonium salts, polyoxyethylene alkylamine salts, and polyethylene polyamine derivatives. The amphoteric surfactants used in this disclosure are not particularly limited, and conventionally known surfactants can be used. Examples include carboxybetaines, aminocarboxylic acids, sulfobetaines, aminosulfate esters, and imitazolines.

[0110] In addition, among the surfactants mentioned above, "polyoxyethylene" can be replaced with "polyoxyalkylenes" such as polyoxymethylene, polyoxypropylene, and polyoxybutylene, and these surfactants can also be used in this disclosure.

[0111] Even more preferred surfactants include fluorinated surfactants containing a perfluoroalkyl group in their molecule. Examples of such fluorinated surfactants include anionic types such as perfluoroalkyl carboxylates, perfluoroalkyl sulfonates, and perfluoroalkyl phosphate esters; amphoteric types such as perfluoroalkyl betaines; cationic types such as perfluoroalkyltrimethylammonium salts; and nonionic types such as perfluoroalkylamine oxides, perfluoroalkyl ethylene oxide adducts, oligomers containing a perfluoroalkyl group and a hydrophilic group, oligomers containing a perfluoroalkyl group and a lipophilic group, oligomers containing a perfluoroalkyl group, a hydrophilic group, and a lipophilic group, and urethanes containing a perfluoroalkyl group and a lipophilic group. Fluorinated surfactants described in Japanese Patent Publication Nos. 62-170950, 62-226143, and 60-168144 are also preferred.

[0112] In addition to the surfactants described above, other surfactants may be added to broaden the stability of the processing under the developing conditions of this disclosure, or to improve the coatability, to the extent that they do not impair the effects of this disclosure. These include amphoteric surfactants as described in Japanese Patent Publication No. 59-121044 and Japanese Patent Publication No. 4-13149; siloxane compounds as described in EP950517; fluorine-containing monomer copolymers as described in Japanese Patent Publication No. 11-288093; and fluorine-based surfactants as described in Japanese Patent Publication No. 62-170950.

[0113] Specific examples of amphoteric surfactants include alkyldi(aminoethyl)glycine, alkylpolyaminoethylglycine hydrochloride, 2-alkyl-N-carboxyethyl-N-hydroxyethylimidazolinium betaine, and N-tetradecyl-N,N-betaine type surfactants (for example, trade name "Amogen K": manufactured by Daiichi Kogyo Co., Ltd.). As for siloxane compounds, block copolymers of dimethylsiloxane and polyalkylene oxide are preferred, and specific examples include polyalkylene oxide-modified silicones such as DBE-224, DBE-621, DBE-712, DBP-732, DBP-534 from Chisso Corporation, and Tego Glide 100 from Tego GmbH, Germany.

[0114] Specific examples of surfactants, including commercially available products, include the following: Please note that "DOWSIL," "XIAMETER," and "SYLGARD" are registered trademarks. The fact that "DOWSIL," "XIAMETER," and "SYLGARD" are registered trademarks will be omitted below.

[0115] Products manufactured by Dow Corning Toray Co., Ltd. include DOWSIL BY 16-205, DOWSIL BY 16-849 Fluid, DOWSIL FZ-3710 Fluid, DOWSIL FZ-3760, DOWSIL FZ-3785, DOWSIL SF 8417 Fluid, DOWSIL BY 16-891, DOWSIL FZ-3789, DOWSIL BY 16-839 Fluid, DOWSIL SF 8411 Fluid, DOWSIL SF 8413 Fluid, DOWSIL SF 8421 Fluid, DOWSIL BY 16-880 Fluid, DOWSIL BY 16-201, DOWSIL SF 8427 Fluid, DOWSIL SF 8428 Fluid, DOWSIL 580 WAX, DOWSIL BY 16-606, DOWSIL BY 16-846 Fluid, XIAMETER OFX-0203 Fluid, XIAMETER OFX-0230 Fluid, DOWSIL SF 8416 Fluid, DOWSIL SF 8419 Fluid, DOWSIL 501W Additive, DOWSIL FZ-2110, DOWSIL FZ-2123, DOWSIL L-7001, SYLGARD OFX-0309 Fluid, XIAMETER OFX-5211 Fluid, DOWSIL SF 8410 Fluid, DOWSIL SH 3746 Fluid, DOWSIL SH 8400 Fluid, DOWSIL SH 8700 Fluid, DOWSIL SH 510 Fluid (100 cSt, 500 cSt), DOWSIL SH 550 Fluid, DOWSIL SH 710 Fluid, DOWSIL FS 1265 Fluid, etc.

[0116] Shin-Etsu Silicone (registered trademark) products from Shin-Etsu Chemical Co., Ltd. include the KP series: KP-124, KP-109, KP-110, KP-121, KP-118, KP-341, KP-112, KP-125, KP-101, KP-106, KP-120, KP-105, KP-104, KP-611, KP-626, KP-327, KP-323, KP-322, KP-625, KP-623, KP-624, KP-620, KP-651, KP-652, KP-650, KP-310, KP-306, KP- 301, KP-621, KP-369, KP-368, KP-126 etc., KF series and FL series etc., KF-868, KF-865, KF-864, KF-859, KF-393, KF-860, KF-880, KF-8004, KF-8002, KF-8005, KF-867, KF-8021, KF-869, KF-861, KF-877, KF-101, KF-1001, KF-102, KF-1002, KF-1005, KF-2001, KF-2004, KF-99, KF-9901, P AM-E, KF-8010, KF-8012, KF-8008, KF-105, KF-6000, KF-6001, KF-6002, KF-6003, KF-6123, KF-9701, KF-2012, KF-857, KF-862, KF-858, KF -351A, KF-352A, KF-353, KF-354L, KF-355A, KF-615A, KF-945, KF-640, KF-642, KF-643, KF-644, KF-6020, KF-6204, KF-6011, KF-6012, KF- Examples include 6015, KF-6017, KF-410, FL-5, FL-100-100cs, FL-100-450cs, FL-100-1,000cs, FL-100-10,000cs, KF-412, KF-413, KF-414, KF-415, KF-4003, KF-4701, KF-4917, KF-7235B, KF-3935, KF-50-100cs, KF-50-300cs, KF-50-1,000cs, KF-50-3,000cs, KF-53, KF-54, KF-6004, etc.

[0117] BYK products include BYK-300, BYK-302, BYK-306, BYK-307, BYK-310, BYK-313, BYK-315 N, BYK-320, BYK-322, BYK-323, BYK-325 N, BYK-326*, BYK-327*, BYK-330, BYK-331, BYK-333, BYK-342, BYK-345 / 346, BYK-347, BYK-348, BYK-349 , BYK-370, BYK-375, BYK-377, BYK-378, BYK-3450*, BYK-3451*, BYK-3455, BYK-3456*, BYK-3760*, BYK-UV 3500, BYK-UV 3505*, BYK-UV 3510, BYK-UV 3530, BYK-UV 3535*, BYK-UV 3570, BYK-UV 3575*, BYK-UV 3576, BYK-350, BYK-354, BYK-355 / 356 Acrylic copolymer, BYK-358 N / 361 N, BYK-381 Acrylic copolymer, BYK-392 Acrylic copolymer, BYK-394 Acrylic copolymer, BYK-3441 Acrylic copolymer, BYK-399, BYK-3440*, BYK-3550, BYK-3560*, BYK-3565*, BYK-3566*, BYK-SILCLEAN Examples include 3700, BYK-SILCLEAN 3701*, BYK-SILCLEAN 3720, and BYK-DYNWET 800 N.

[0118] [Other ingredients] In addition, the upper layer of the two-layer image recording layer may contain an acid generator, an acid growth agent, a development accelerator, a printing agent, a colorant, a plasticizer, a wax, etc. Furthermore, in a two-layer image recording layer, a development accelerator may be included not only in the upper layer but also in the lower layer for the purpose of adjusting the dissolution rate of the image recording layer. That is, the development accelerator may be included in at least one of the upper or lower layers, or it may be included in both the upper and lower layers. Examples of development accelerators include acid anhydrides, phenols, and organic acids, and examples of sulfonium salt A(b-1), sulfonium salt B(b-2), phenolic compound (a-2), and phenolic compound (c-1) described in the examples below are also included. These components can be the same as those used in the positive-type photosensitive resin composition according to the present disclosure, as described above, and the preferred embodiments are also the same.

[0119] The upper layer preferably further contains a polymer having a structural unit having an alkyl fluoride in its side chain. The upper layer contains a polymer having a structural unit with a fluorinated alkyl group in its side chain, resulting in a good coating surface when the upper layer is applied, and further improving the ink receptivity of the image area in a lithographic printing plate. Examples of polymers having structural units with alkyl fluoride side chains include the compounds listed below. The following compounds are available commercially, and examples of commercially available products include fluorine-based surfactants (Megafac (registered trademark, hereinafter the same) F-782F, DIC Corporation).

[0120] [ka]

[0121] Furthermore, it is preferable that at least one of the upper layer and the lower layer described later contains a polymer having a structural unit represented by the following formula (I), and it is more preferable that the polymer having a structural unit represented by the following formula (I) is contained in the upper layer.

[0122] Furthermore, in order to improve the surface texture of the coating when the upper layer is coated, and the ink-receiving properties of the image area in a lithographic printing plate, polymers having siloxane bonds in their side chains are also preferred, in addition to polymers having structural units with alkyl fluoride in their side chains. An example of a specific structure is a polymer obtained by changing the structural unit having alkyl fluoride in the polymer of the above structure to a structural unit having a tribranched siloxane structure.

[0123] Examples of constituent units having a tribranched siloxane structure include the following:

[0124] [ka]

[0125] Examples of polymers obtained by changing the structural unit containing the alkyl fluoride in the side chain to a structural unit having a tribranched siloxane structure include the polymers shown below.

[0126] [ka]

[0127] There are no particular restrictions on the main chain skeleton of polymers having structural units containing alkyl fluoride in their side chains, and polymers having siloxane bonds in their side chains, and examples include acrylic skeletons and methacrylic skeletons. The main chain skeletons of each structural unit constituting the polymer may be the same or different from one another.

[0128] [ka]

[0129] In formula (I), R 11 and R 12 Each of these independently represents a hydrogen atom or an alkyl group, R 13 represents a hydrogen atom or a monovalent substituent, L 11 and L 12 Each of these independently represents a single bond or a divalent linking group, and Rh represents a substituent containing two or more silicon atoms.

[0130] In formula (I), R 11 and R 12 Each of these independently represents a hydrogen atom or an alkyl group, R 13represents a hydrogen atom or a monovalent substituent, L 11 and L 12 Each of these independently represents a single bond or a divalent linking group, and Rh represents a substituent containing two or more silicon atoms.

[0131] R 11 and R 12 Examples of alkyl groups represented by include linear alkyl groups having 1 to 18 carbon atoms, branched alkyl groups having 3 to 18 carbon atoms, or cyclic alkyl groups. Specifically, examples of the above alkyl groups include methyl group, ethyl group, propyl group, butyl group, isopropyl group, tert-butyl group, cyclohexyl group, and the like. R 11 and R 12 Preferably, all of these are hydrogen atoms.

[0132] R 13 Examples of monovalent substituents represented by include alkyl groups, alkenyl groups, or aryl groups.

[0133] L 11 Divalent linking groups represented by include -C(=O)-O- (so-called ester bond) or -C(=O)-NH-. Note L 11 The divalent linking group represented is preferably an ester bond, -C(=O)-O-.

[0134] L 12 The divalent linking group represented by is L 11 There are no particular restrictions as long as it is a group that can link L with Rh. 12 Examples of divalent linking groups represented by include alkylene groups. Preferably, the alkylene group has 2 to 10 carbon atoms, and more preferably, it has 4 to 8 carbon atoms.

[0135] As the substituent containing two or more silicon atoms represented by Rh, there is no particular limitation as long as two or more silicon atoms are contained in the atomic group constituting the substituent. From the viewpoint of in-air developability, the substituent containing two or more silicon atoms preferably contains silicon atoms as silicon-oxygen bonds (Si-O bonds). The substituent containing two or more silicon atoms preferably has two or more silicon-oxygen bonds, more preferably three or more silicon-oxygen bonds, and even more preferably three to twelve silicon-oxygen bonds. The substituent containing two or more silicon atoms preferably contains silicon-oxygen bonds in a polysiloxane structure. In addition, from the viewpoint of in-air developability, the substituent containing two or more silicon atoms preferably has a branched structure, and more preferably has a branched structure branched around a silicon atom.

[0136] Specifically, the substituent containing two or more silicon atoms is preferably a group containing two or more structures represented by the following formula (BIa).

[0137] [Chemical formula]

[0138] In the above formula (BIa), * represents the bonding position, and R b11 , R b12 , and R b13 each independently represent an alkyl group, an alkenyl group, an aryl group, or an alkylene aryl group.

[0139] R b11 , R b12 , and R b13 Examples of the alkyl group represented by include linear alkyl groups having 1 to 18 carbon atoms, branched or cyclic alkyl groups having 3 to 18 carbon atoms. Specific examples of the above alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, an isopropyl group, a tert-butyl group, a cyclohexyl group, and the like. R b11 , R b12 , and R b13Examples of the alkenyl group represented by [the formula] include alkenyl groups having 2 to 12 carbon atoms. Specific examples of the alkenyl group include a vinyl group, a 1-propenyl group, a 1-butenyl group, a 1-methyl-1-propenyl group, a 1-cyclopentenyl group, a 1-cyclohexenyl group, and the like. R b11 、R b12 、and R b13 Examples of the aryl group represented by [the formula] include aryl groups having 6 to 12 carbon atoms. Specific examples of the aryl group include a phenyl group, an α-methylphenyl group, a naphthyl group, and the like. R b11 、R b12 、and R b13 Examples of the alkylene aryl group represented by [the formula] include alkylene aryl groups having 7 to 30 carbon atoms.

[0140] In formula (BIa), R b11 、R b12 、and R b13 are each preferably an alkyl group, more preferably all the same alkyl group, still more preferably all alkyl groups having 1 to 4 carbon atoms, and particularly preferably all methyl groups.

[0141] The substituent containing two or more silicon atoms is preferably a group containing three or more structures represented by the above formula (BIa), and more preferably a group containing 3 to 6 thereof.

[0142] The substituent containing two or more silicon atoms is preferably a group represented by the following formula (Ba2).

[0143] [Chemical formula]

[0144] In the above formula (Ba2), * represents the bonding position, and R b1 、R b2 、and R b3Each independently represents an alkyl group, an alkenyl group, an aryl group, or an alkylene aryl group. R b1 、R b2 、and R b3 Examples of the alkyl group represented by R b1 , R b2 , and R b3 include linear alkyl groups having 1 to 18 carbon atoms, branched or cyclic alkyl groups having 3 to 18 carbon atoms. Specific examples of the above alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, an isopropyl group, a tert-butyl group, a cyclohexyl group, and the like. R b1 、R b2 、and R b3 Examples of the alkenyl group represented by R b1 , R b2 , and R b3 include alkenyl groups having 2 to 12 carbon atoms. Specific examples of the above alkenyl group include a vinyl group, a 1-propenyl group, a 1-butenyl group, a 1-methyl-1-propenyl group, a 1-cyclopentenyl group, a 1-cyclohexenyl group, and the like. R b1 、R b2 、and R b3 Examples of the aryl group represented by R b1 , R b2 , and R b3 include aryl groups having 6 to 12 carbon atoms. Specific examples of the above aryl group include a phenyl group, an α-methylphenyl group, a naphthyl group, and the like. R b1 、R b2 、and R b3 Examples of the alkylene aryl group represented by R b1 , R b2 , and R b3 include alkylene aryl groups having 7 to 30 carbon atoms.

[0145] In formula (Ba2), R b1 , R b2 , and R b3 are each preferably an alkyl group, more preferably all the same alkyl group, still more preferably all alkyl groups having 1 to 4 carbon atoms, and particularly preferably all methyl groups. b1 、R b2 、and R b3 はそれぞれ独立にアルキル基であることが好ましく、全て同じアルキル基であることがより好ましく、全て炭素数1~4のアルキル基であることが更に好ましく、全てメチル基であることが特に好ましい。

[0146] Specific examples of the constituent unit (Bb1) represented by formula (I) include monomers represented by K-1 to K-12. However, the specific examples of monomer units that form a constituent unit having substituents containing two or more silicon atoms in their side chains are not limited to these. In the following structure, n is an integer between 2 and 1000.

[0147] [ka]

[0148] From the viewpoint of obtaining better coating film surface properties, the constituent unit represented by formula (I) is preferably a copolymer comprising a constituent unit having a substituent containing two or more silicon atoms in its side chain and a constituent unit having a hydrophilic group in its side chain.

[0149] The constituent unit having a hydrophilic group in its side chain, as represented by formula (I), is preferably the constituent unit represented by the following formula (a4).

[0150] [ka]

[0151] In formula (Ba4), R B7 and R B8 Each of these independently represents a hydrogen atom or an alkyl group, R B9 represents a hydrogen atom or a monovalent substituent, L B2 represents -C(=O)-O- or -C(=O)-NH-, L B2 and L B3 represents a single bond or a divalent linking group, X B This represents a hydrophilic group.

[0152] R B7 and R B8 The alkyl group represented by R 4 and R 5 Each of these independently represents either a hydrogen atom or an alkyl group. R B7 and R B8Examples of alkyl groups represented by include linear alkyl groups having 1 to 18 carbon atoms, branched alkyl groups having 3 to 18 carbon atoms, or cyclic alkyl groups. Specifically, examples of the above alkyl groups include methyl group, ethyl group, propyl group, butyl group, isopropyl group, tert-butyl group, cyclohexyl group, and the like. R B7 and R B8 Preferably, all of these are hydrogen atoms.

[0153] R B9 Examples of monovalent substituents represented by include alkyl groups, alkenyl groups, or aryl groups. The alkyl groups, alkenyl groups, and aryl groups are R B11 , R B12 , and R B13 The alkyl group, alkenyl group, and aryl group represented by are the same, and the preferred embodiment is also the same. R B9 Preferably, it is a hydrogen atom or a methyl group.

[0154] L B3 The divalent linking group represented by is L B2 and X B There are no particular restrictions as long as it is a group that can connect to L. B3 Examples of divalent linking groups represented by include alkylene groups. Preferably, the alkylene group has 2 to 10 carbon atoms, and more preferably, it has 4 to 8 carbon atoms.

[0155] X B The hydrophilic groups represented by include hydroxyl groups, phosphate groups, polyalkylene oxy groups, or groups formed by combining two or more of these. Here, polyalkylene oxy groups include polyethylene oxy groups, polypropylene oxy groups, polybutylene oxy groups, or groups formed by combining these.

[0156] Specific examples of monomer units for forming a structural unit having a hydrophilic group in the side chain include monomers (monomers) represented by H-1 to H-40. Specific examples of monomer units for forming a structural unit having a hydrophilic group in the side chain are not limited to these. In the following structures, n and m are each independently an integer of 2 to 100. In the following structure, the description "random" means that a plurality of types of polyalkyleneoxy groups are arranged randomly.

[0157]

Chemical formula

[0158]

Chemical formula

[0159] The polymer having a structural unit represented by formula (I) (hereinafter also referred to as polymer A) may contain, alone or in combination of two or more, a structural unit having a substituent containing two or more silicon atoms in the side chain. In polymer A, the content of the structural unit having a substituent containing two or more silicon atoms in the side chain may be 100% by mass based on the mass of polymer A, preferably 15% to 70% by mass, more preferably 20% to 60% by mass, and still more preferably 25% to 50% by mass. Also, polymer A may contain, alone or in combination of two or more, a structural unit having a hydrophilic group in the side chain. In polymer A, the content of the structural unit having a hydrophilic group in the side chain is preferably 30% to 85% by mass, more preferably 40% to 80% by mass, and still more preferably 50% to 75% by mass based on the mass of polymer A.

[0160] Note that polymer A may further contain other structural units. Other structural units include, for example, structural units having a carboxylic acid group in their side chain. Examples of structural units having a carboxylic acid group in their side chain include (meth)acrylic acid, itaconic acid, and itaconic acid derivatives. It is preferable that structural units having a carboxylic acid group in their side chain are included as separate structural units from the structural units having a hydrophilic group in their side chain as described above. Other constituent units include alkyl (meth)acrylate (alkyl group has 1 to 24 carbon atoms), styrene derivatives, maleic anhydride, maleimide anhydride, (meth)acrylonitrile, vinyl ether derivatives, and alkyl (meth)acrylamide derivatives. In polymer A, the content of other constituent units is preferably 0% to 20% by mass relative to the mass of polymer BB.

[0161] The weight-average molecular weight of polymer A is preferably 5,000 to 100,000, and more preferably 8,000 to 60,000, from the viewpoint of obtaining an image recording layer with excellent planar properties.

[0162] Specific examples of polymer A include BP-1 to BP-10, shown below. However, specific examples of polymer A are not limited to these.

[0163] [ka]

[0164] The content of polymer A is preferably 0.001% to 0.1% by mass, and more preferably 0.002% to 0.01% by mass, relative to the total mass of the image recording layer coating solution.

[0165] In the disclosure, unless otherwise specified, the term "lithographic printing plate master related to this disclosure" refers to both the embodiment having a single-layer image recording layer and the multi-layer image recording layer having a lower layer and an upper layer. Furthermore, unless otherwise specified, the term "image recording layer," etc., refers to both the single-layer and multi-layer image recording layers, etc.

[0166] As a result of diligent research by the present inventors, we have found that by adopting the above configuration, it is possible to provide a lithographic printing plate master having an image recording layer with excellent coating surface properties. The detailed mechanism by which the above effects are achieved is unknown, but it is speculated to be as follows. In the first embodiment described above, the (meth)acrylic polymer having substituents containing two or more silicon atoms in its side chains, as contained in the image recording layer, is thought to be prone to uneven distribution on the surface when forming the image recording layer due to the structure of its side chains, and thus contributes to the surface smoothness of the image recording layer. Furthermore, the polymer having the constituent unit represented by formula (I) contained in the image recording layer is thought to be prone to uneven distribution on the surface when forming the image recording layer due to the structure of its side chains, and thus contributes to the surface smoothness of the image recording layer. As a result, it is estimated that unevenness will be less visible when the surface is inspected, and an excellent image recording layer will be obtained on the coating surface.

[0167] <lower layer> In this disclosure, the lower layer of the two-layer image recording layer is preferably a layer containing the positive-type photosensitive resin composition according to this disclosure. Furthermore, it is preferable that the lower layer of the two-layer image recording layer in this disclosure is formed by applying the positive-type photosensitive resin composition according to this disclosure. By using the positive-type photosensitive resin composition according to this disclosure as a lower layer, a printing plate with excellent image formation properties and print durability can be obtained. Furthermore, by using the positive-type photosensitive resin composition according to this disclosure as a lower layer, the print resistance is improved. Although the detailed mechanism by which the above effects are obtained is unknown, it is presumed that the film strength of the resin used in the lower layer is important for print durability. Therefore, it is estimated that print durability will be improved by using the positive-type photosensitive resin composition according to this disclosure, which has high film strength due to strong interactions (such as hydrogen bonding) between binders, in the lower layer.

[0168] From the viewpoint of improving print resistance, it is preferable that the alkali-soluble resin contained in the lower layer includes at least one selected from acrylic resins having sulfonamide groups in their side chains, acrylic resins having phenolic hydroxyl groups in their side chains, and novolac resins. By including the alkali-soluble resin in the lower layer, the interaction between the binders (such as hydrogen bonding) is strengthened, which is thought to contribute to improved film strength and, as a result, better print resistance.

[0169] When the positive-type photosensitive resin composition according to this disclosure is used as the upper layer, it is preferable that the lower layer is also formed using the positive-type photosensitive resin composition according to this disclosure. However, the lower layer may also be formed using a resin composition other than the positive-type photosensitive resin composition according to this disclosure. In that case, the preferred embodiment of the lower layer is the same as the preferred embodiment of the upper layer described above. In particular, it is believed that including a polymer having the constituent unit represented by the above formula (I) in the lower layer further improves the surface quality of the coating film in the lower layer.

[0170] <Support> The support used for the positive lithographic printing plate master according to this disclosure is not particularly limited as long as it is a dimensionally stable plate-like material with the necessary strength and durability, and a support similar to those described in paragraphs 0166 to 0169 of International Publication No. 2016 / 047392 can be used. Among the above, an aluminum support is particularly preferred, and an aluminum support that has undergone hydrophilic treatment is preferred.

[0171] <Undercoat layer> The positive type lithographic printing plate master according to this disclosure preferably has an undercoat layer between the support having the hydrophilic surface and the image recording layer. Various organic compounds can be used as undercoat components. For example, carboxymethylcellulose, phosphonic acids having amino groups such as dextrin, organic phosphonic acids, organic phosphoric acids, organic phosphinic acids, amino acids, and hydrochloride salts of amines having hydroxyl groups are preferred. These undercoat components may be used individually or in combination of two or more. Details of the compounds used in the undercoat and the method for forming the undercoat are described in paragraphs 0171 to 0172 of Japanese Patent Application Publication No. 2009-175195, and these descriptions also apply to this disclosure. For example, the undercoat preferably contains at least one selected from the group consisting of phosphonic acids having an amino group, organic phosphonic acids, organic phosphoric acids, organic phosphinic acids, amino acids, and hydrochloride salts of amines having a hydroxyl group. The above compounds may be included as partial structures of polymers, and specific examples include polymers with the following structures.

[0172] [ka]

[0173] The coverage amount of the undercoat layer is 2 mg / m². 2 ~200mg / m 2 Preferably, it is 5 mg / m² 2 ~100mg / m 2 It is more preferable that the amount of coating is within the above range.

[0174] <Backcoat layer> A back coat layer is provided on the back surface of the support of the positive-type lithographic printing plate master according to this disclosure, if necessary. Preferably, such a back coat layer is a coating layer made of a metal oxide obtained by hydrolysis and polycondensation of an organic polymer compound described in Japanese Patent Publication No. 5-45885 and an organic or inorganic metal compound described in Japanese Patent Publication No. 6-35174. Among these coating layers, silicon alkoxy compounds such as Si(OCH3)4, Si(OC2H5)4, Si(OC3H7)4, and Si(OC4H9)4 are inexpensive and readily available, and the metal oxide coating layer obtained therefrom is particularly preferred because it has excellent resistance to developing solutions.

[0175] (Method for creating lithographic printing plates) The method for producing a lithographic printing plate according to this disclosure includes, in this order, an exposure step of image exposure of a positive lithographic printing plate according to this disclosure, and a development step of developing the exposed positive lithographic printing plate using an alkaline aqueous solution with a pH of 8.5 to 13.5. According to the method for producing lithographic printing plates described herein, the development discrimination is excellent, allowing for the formation of fine images, and furthermore, a lithographic printing plate with excellent print durability can be obtained. As previously described, the method for producing a lithographic printing plate according to this disclosure can be applied to positive-type lithographic printing plates having either a single-layer image recording layer or multiple-layer image recording layers. The following describes in detail each step of the method for producing the lithographic printing plate related to this disclosure.

[0176] <Exposure process> The method for producing a lithographic printing plate relating to this disclosure includes an exposure step of image exposure of a positive lithographic printing plate according to this disclosure. Details are the same as those described in paragraphs 0173 to 0175 of International Publication No. 2016 / 047392.

[0177] <Developing process> The method for producing a lithographic printing plate according to this disclosure includes a developing step in which the plate is developed using an alkaline aqueous solution with a pH of 8.5 to 13.5 (hereinafter also referred to as "developer"). The developing solution used in the developing process is an aqueous solution with a pH of 8.5 to 13.5, and an alkaline aqueous solution with a pH of 12 to 13.5 is more preferred. Furthermore, the developer solution preferably contains a surfactant, and more preferably contains at least an anionic surfactant or a nonionic surfactant. The surfactant contributes to improved processability. The surfactant used in the above-mentioned developer can be anionic, nonionic, cationic, or amphoteric, but as previously stated, anionic or nonionic surfactants are preferred. As anionic, nonionic, cationic, and amphoteric surfactants used in the developing solution in the method for producing lithographic printing plates according to this disclosure, those described in paragraphs 0128 to 0131 of Japanese Patent Application Publication No. 2013-134341 may be used.

[0178] Furthermore, from the viewpoint of stable solubility or turbidity in water, an HLB (Hydrophile-Lipophile Balance) value of 6 or higher is preferred, and a value of 8 or higher is more preferred. As surfactants used in the above-mentioned developing solution, anionic surfactants and nonionic surfactants are preferred, and anionic surfactants containing sulfonic acid or sulfonate salts and nonionic surfactants having an aromatic ring and an ethylene oxide chain are particularly preferred. Surfactants can be used alone or in combination. The surfactant content in the developer solution is preferably 0.01% to 10% by mass, and more preferably 0.01% to 5% by mass.

[0179] To maintain the above developer solution at a pH of 8.5 to 13.5, the presence of carbonate ions and bicarbonate ions as buffering agents suppresses pH fluctuations even when the developer solution is used for a long period of time, thereby suppressing a decrease in developing performance and the generation of developer residue due to pH fluctuations. To make carbonate ions and bicarbonate ions present in the developer solution, carbonate salts and bicarbonate salts may be added to the developer solution, or carbonate ions and bicarbonate ions may be generated by adjusting the pH after adding carbonate salts or bicarbonate salts. The carbonate salts and bicarbonate salts are not particularly limited, but alkali metal salts are preferred. Examples of alkali metals include lithium, sodium, and potassium, with sodium being particularly preferred. These may be used individually or in combination of two or more.

[0180] The total amount of carbonates and bicarbonates is preferably 0.3% to 20% by mass, more preferably 0.5% to 10% by mass, and particularly preferably 1% to 5% by mass, relative to the total mass of the developer. If the total amount is 0.3% by mass or more, the developing ability and processing capacity will not decrease, and if it is 20% by mass or less, it will be difficult for precipitates and crystals to form, and furthermore, it will be difficult for gel to form during neutralization when the developer wastewater is treated, thereby suppressing the possibility of problems occurring during wastewater treatment.

[0181] It is preferable to provide a drying process, either continuously or discontinuously, after the developing process. Drying can be carried out by hot air, infrared radiation, far-infrared radiation, etc. In the method for producing a lithographic printing plate according to this disclosure, a suitable automatic processing machine is used, which has a developing section and a drying section. In this method, a positive-type lithographic printing plate is developed and gummed in the developing section, and then dried in the drying section to obtain a lithographic printing plate.

[0182] Furthermore, to improve print durability and other properties, the developed printing plate can be heated under very strong conditions. This heating process is also referred to as the post-heating process. The heating temperature in the post-heating process is preferably in the range of 200°C to 500°C from the viewpoint of achieving the desired image enhancement effect and suppressing thermal decomposition of the image area. The resulting lithographic printing plates are then fed into an offset printing press and are suitable for printing large quantities of copies. [Examples]

[0183] The present invention will be described in detail below with reference to examples. The materials, amounts used, proportions, processing content, and processing procedures shown in the following examples can be modified as appropriate without departing from the spirit of the embodiments of the present invention. Therefore, the scope of the embodiments of the present invention is not limited to the specific examples shown below. In these examples, "parts" and "%" mean "parts by mass" and "% by mass" respectively, unless otherwise specified.

[0184] [Examples 1-27, Comparative Examples 1-11] <Preparation of specific compounds> The specific compounds related to this disclosure are commercially available. These specific compounds are commercially available in the form of reagents or chemical products from companies such as Tokyo Chemical Industry, Fujifilm Wako Pure Chemical Industries, Sigma-Aldrich, and Kanto Chemical.

[0185] <Preparation of support> A support for lithographic printing plates was manufactured by subjecting a 0.3 mm thick aluminum alloy plate of material 1S to the processes described below (Aa) to (Ak). Water washing was performed between all processing steps, and after water washing, the material was de-drained using a nip roller. (Aa) Mechanical surface roughening treatment (brush grain method) Pumice suspension (specific gravity 1.1 g / cm³) 3 While supplying the polishing slurry to the surface of the aluminum plate, mechanical surface roughening treatment was performed using a rotating bundled brush. The median diameter (μm) of the abrasive material was set to 30 μm, the number of brushes to 4, and the brush rotation speed (rpm: revolutions / minute, the same applies hereafter) to 250 rpm. The material of the bundled brush was 6,10 nylon, with a bristle diameter of 0.3 mm and a bristle length of 50 mm. The brush was densely packed into a φ300 mm stainless steel cylinder with holes drilled in it. The distance between the two support rollers (φ200 mm) at the bottom of the bundled brush was 300 mm. The bundled brush was pressed against the aluminum plate until the load on the drive motor that rotates the brush was 10 kW more than the load before the bundled brush was pressed against the aluminum plate. The direction of brush rotation was the same as the direction of movement of the aluminum plate. (Ab) Alkali etching treatment The aluminum plate obtained above was etched by spraying an aqueous solution of caustic soda with a concentration of 26% by mass of caustic soda and an aluminum ion concentration of 6.5% by mass onto it using a spray tube at a temperature of 70°C. Afterward, it was rinsed with water using a spray. The amount of aluminum dissolved was 10 g / m². 2 That was the case. (Ac) Desmat treatment in acidic aqueous solution Next, a desmatt treatment was performed in an aqueous nitric acid solution. The aqueous nitric acid solution used for the desmatt treatment was the waste liquid from the electrochemical surface roughening process in the next step. The temperature of the solution was 35°C. The desmatt solution was sprayed onto the surface and the treatment was performed for 3 seconds. (Ad) Electrochemical surface roughening treatment Electrochemical surface roughening was continuously performed using a 60Hz AC voltage with nitric acid electrolysis. The electrolyte used was an aqueous solution of 10.4g / L nitric acid at 35°C, to which aluminum nitrate was added to adjust the aluminum ion concentration to 4.5g / L. The AC power waveform used was a trapezoidal rectangular wave AC with a current peak time tp of 0.8msec, a duty cycle of 1:1, and a carbon electrode as the counter electrode. Ferrite was used as the auxiliary anode. The current density was 30A / dm² at the peak current value. 2 5% of the current flowing from the power supply was diverted to the auxiliary anode. Electrical quantity (C / dm 2 ) is the total amount of electric charge when the aluminum plate is at anode, which is 185 C / dm2 That was the case. Afterwards, it was rinsed with water using a spray bottle. (Ae) Alkaline etching treatment The aluminum plate obtained above was etched by spraying an aqueous solution of caustic soda with a concentration of 5% by mass of caustic soda and an aluminum ion concentration of 0.5% by mass onto it using a spray tube at a temperature of 50°C. Afterward, it was rinsed with water using a spray. The amount of aluminum dissolved was 0.5 g / m². 2 That was the case. (Af) Desmat treatment in acidic aqueous solution Next, a desmatt treatment was performed in an aqueous sulfuric acid solution. The aqueous sulfuric acid solution used for the desmatt treatment had a sulfuric acid concentration of 170 g / L and an aluminum ion concentration of 5 g / L. The temperature of the solution was 30°C. The desmatt solution was sprayed and the desmatt treatment was performed for 3 seconds. (Ag) Electrochemical roughening treatment Electrochemical surface roughening was continuously performed using hydrochloric acid electrolysis with a 60 Hz AC voltage. The electrolyte used was an aqueous solution of 6.2 g / L hydrochloric acid at a liquid temperature of 35°C, to which aluminum chloride was added to adjust the aluminum ion concentration to 4.5 g / L. Electrochemical surface roughening was performed using a trapezoidal rectangular wave AC current with a current value of 0.8 msec (tp) from zero to peak, a duty cycle of 1:1, and a carbon electrode as the counter electrode. Ferrite was used as the auxiliary anode. The current density is 25 A / dm² at the peak current value. 2 Therefore, the amount of electricity in hydrochloric acid electrolysis (C / dm 2 ) is the total amount of electricity when the aluminum plate is at anode, which is 63C / dm 2 That was the case. Afterwards, it was rinsed with water using a spray bottle. (Ah) Alkali etching treatment The aluminum plate obtained above was etched by spraying an aqueous solution of caustic soda with a concentration of 5% by mass of caustic soda and an aluminum ion concentration of 0.5% by mass onto it using a spray tube at a temperature of 50°C. Afterward, it was rinsed with water using a spray. The amount of aluminum dissolved was 0.1 g / m². 2 That was the case. (Ai) Desmat treatment in acidic aqueous solution Next, a desmatt treatment was performed in an aqueous sulfuric acid solution. Specifically, waste liquid generated in the anodizing process (5 g / L of aluminum ions dissolved in 170 g / L aqueous sulfuric acid solution) was used, and the desmatt treatment was performed at a liquid temperature of 35°C for 4 seconds. The desmatt solution was sprayed and the desmatt treatment was performed for 3 seconds. (Aj) Anodizing treatment Anodizing was performed using a two-stage electrolytic anodizing apparatus (6m each for the first and second electrolytic sections, 3m each for the first and second power supply sections, and 2.4m each for the first and second supply electrode sections). Sulfuric acid was used as the electrolyte supplied to the first and second electrolytic sections. Both electrolytes had a sulfuric acid concentration of 50g / L (containing 0.5% by mass of aluminum ions) and were heated to 20°C. Afterwards, the samples were rinsed with water using a spray. (Ak) Silicate treatment To ensure hydrophilicity in the non-image areas, silicate treatment was performed by dipping the sample in a 2.5% by mass aqueous solution of sodium silicate no. 3 at 50°C for 7 seconds. The amount of Si deposited was 10 mg / m². 2 That was the case. Afterwards, it was rinsed with water using a spray bottle.

[0186] <Formation of the undercoat layer> After applying the primer coating liquid 1 shown below onto the support prepared as described above, it was dried at 80°C for 15 seconds to form a primer layer and complete the support. The coverage amount after drying was 15 mg / m². 2 That was the case. [Primer coating liquid 1] • The following copolymer with a weight-average molecular weight of 28,000: 0.3 parts · Methanol: 100 parts ·Wed: 1 part

[0187] [ka]

[0188] In the chemical formulas above, the subscripts in parentheses represent the content (mass %) of each constituent unit.

[0189] <Formation of the image recording layer> The obtained support was coated with the following underlayer-forming coating composition (I) using a wire bar, and dried in a 150°C drying oven for 40 seconds to obtain a coating amount of 1.0 g / m². 2 The lower layer is formed in this manner. The upper layer is formed by applying the upper layer formation coating liquid composition (II) with the following composition to the surface of the lower layer using a wire bar. After applying the upper layer, it is dried at 150°C for 40 seconds, and the total coating amount of the lower and upper layers is 1.2 g / m². 2 A lithographic printing plate is obtained.

[0190] [Coating liquid composition for forming the lower layer (I)] N-(4-aminosulfonylphenyl)methacrylamide / acrylonitrile / methyl methacrylate copolymer (copolymerization ratio: 32 / 36 / 32: weight-average molecular weight 50000): 2.5 parts m,p-cresol novolac: 0.4 parts • Specific compounds or comparative compounds with the following structure (compounds listed in Tables 1 to 7): Amounts listed in Tables 1 to 7 • Infrared absorber (IR dye (I): structure shown below): 0.2 parts • Tetrahydrophthalic anhydride (THPA): 0.3 parts or not included (as listed in Tables 1-7) • p-toluenesulfonic acid (p-TsO): 0.02 parts or not present (as listed in Tables 1 to 7) · 3-Methoxy-4-diazodiphenylamine hexafluorophosphate: 0.1 part • Ethyl violet with the counterion replaced by 6-hydroxynaphthalenesulfonic acid: 0.15 parts • Fluorine-based surfactant (Megafac F-780F, DIC Corporation, see structure (e-1)): 0.01 parts • Silicone-based surface modifier (BYK-300, BYK Japan Co., Ltd.): 0.01 parts or not included (as listed in Tables 1 to 7) • Siloxane-based surface modifier (additive (e-2): 0.01 part or not included (as listed in Tables 1 to 7)) Methyl ethyl ketone: 30 parts 1-Methoxy-2-butyrolactone: 15 parts • γ-butyrolactone: 15 parts

[0191] [ka]

[0192] [ka]

[0193] [ka]

[0194] [ka]

[0195] [Coating liquid composition for upper layer formation (II)] Novolac resin (m-cresol / p-cresol / phenol = 3 / 2 / 5, Mw 8,000): 0.68 parts • Ethyl methacrylate / isobutyl methacrylate / methacrylic acid copolymer (copolymerization ratio: 50 / 20 / 30: weight-average molecular weight 42000): 0.16 parts • Infrared absorber (IR dye (I): structure shown above): 0.045 parts Methyl ethyl ketone: 15.0 parts · 1-Methoxy-2-propanol: 30.0 parts Sulfonate A (structure shown below: b-1): 0.16 parts • Sulfonate B (structure shown below: b-2): 0.16 parts • Fluorine-based surfactant (Megafac F-782F, DIC Corporation, see structure in (d-1)): 0.01 parts or not included • Siloxane-based surfactants (compounds with structures (d-2) to (d-6) below): 0.01 parts or not present • Additives with the following structure (compounds listed in Tables 1-7): Amounts (parts) as listed in Tables 1-7 In the structural formula below, the composition ratio of each constituent unit is expressed as weight percent, with the total amount of each constituent unit being 100% by mass. MW represents the weight-average molecular weight.

[0196] [ka]

[0197] [ka]

[0198] [ka]

[0199] In Tables 1 to 7, the values ​​for content represent parts by mass, and "-" indicates that the compound is not present. The following evaluations were performed using the lithographic printing plates obtained for each example and comparative example, and the results are shown in Tables 1 to 7 below.

[0200] <Evaluation of dissolution resistance of image area and development time of non-image area> In each example and comparative example, the positive type lithographic printing plate original was printed with a test pattern as an image using a Creo Trendsetter VX with a beam intensity of 9W and a drum rotation speed of 150rpm. Subsequently, the film is immersed in a developing bath containing Fujifilm XP-D developer (diluted to achieve a conductivity of 42 mS / cm), and the time until the image area begins to dissolve at a developing temperature of 28°C, as well as the time required for development of the non-image areas, are measured. The time until the image area begins to dissolve is defined as the time until the measured optical density (OD value) in the image area decreases by 0.05 from the measured optical density in the image area before development. Furthermore, the immersion time until the difference between the measured optical density in the non-image area and the measured optical density of the aluminum support becomes 0.02 or less is defined as the non-image area development time. In both cases, the optical density is measured using a GretagMacbeth SpectroEye spectrophotometer. The longer the time until the image area begins to dissolve, the better the resistance to alkaline aqueous solutions. Conversely, the shorter the development time for the non-image area, the better the solubility in alkaline aqueous solutions in the non-image area, and the better the alkaline aqueous solution developability (highlight reproduction). Therefore, in a positive type lithographic printing plate, the longer the time until the image area begins to dissolve, the shorter the development time for the non-image area, and the larger the difference between the time until the image area begins to dissolve and the development time for the non-image area, the better the developability is evaluated. In the following tables, the above difference is indicated as "development discrimination". The shorter the development time for non-image areas, the better the suppression of residual color, as mentioned above. The results are shown in Tables 1 to 7.

[0201] <Evaluation of scratch resistance> The resulting lithographic printing plate is scratched on the surface using a HEIDON scratch tester, applying a load to a sapphire needle (tip diameter 1.0 mm). Then, it is exposed to light using a Creo Trendsetter 3244 with a beam intensity of 9.0 W and a drum rotation speed of 150 rpm, as shown in the image. Using a Fujifilm LP940H PS processor loaded with Fujifilm DT-2 developer (diluted 1:8) and Fujifilm FG-1 Fiescher (diluted 1:1), develop the film at a temperature of 30°C for 12 seconds. The conductivity of the developer at this time is 43 mS / cm. The maximum load (g) that remained scratch-free after visual inspection of the developed lithographic printing plates was used as the scratch resistance value. A higher value indicates superior scratch resistance. A scratch resistance rating of 7 or higher is considered acceptable for practical use, 8 or higher is preferable, and 10 or higher is even more preferable. The results are shown in Tables 1 to 7 below.

[0202] <Evaluation of print durability> In each example and comparative example, a test pattern was drawn onto the positive type lithographic printing plate using a Creo Trendsetter with a beam intensity of 9W and a drum rotation speed of 150rpm. Using a Fujifilm XP-D developer (diluted to a conductivity of 43 mS / cm) loaded into a Fuji Photo Film Co., Ltd. PS processor LP940H, development of the non-image areas was performed at a development temperature of 30°C for a development time of 12 seconds. This was then continuously printed using a Komori Corporation Lithrone printing press. As an ink model for low-grade materials, Toyo Tokuren Sumi ink containing calcium carbonate was used. The number of prints that could be printed while maintaining sufficient ink density was measured visually to evaluate print durability. A higher number of prints indicated better print durability. The results are shown in Tables 1 to 7.

[0203] <Evaluation of coating surface condition> The prepared lithographic printing plate is processed to 40 cm x 62 cm. The outermost surface of the resulting sample is visually observed under white light illumination of 750-1500 Lux, and the surface texture is evaluated according to the following criteria. The results are shown in Tables 1 to 7. -standard- A: No unevenness is visible at all. B: Slight unevenness is visible in some areas. Slight unevenness is visible in a wider area than in C:B.

[0204] <Evaluation of ink transfer properties> The positive-type lithographic printing plates used in each example and comparative example were loaded into a plate material supply device, continuously exposed to light automatically, developed using the developer solution described above, and discharged into a stocker. The exposure resolution was 2,400 dpi (dots per inch, number of dots per inch = 2.54 cm) and 175 lines, with the halftone dots varied from 0.5% to 99.5%. The obtained lithographic printing plates were printed using a Man-Roland R201 printing press with DIC Graphics Co., Ltd.'s DICure Abilio ink. Visual inspection was performed to confirm that there were no areas without ink adhesion in the printed area, and the number of prints required to achieve this was used as an indicator of ink adhesion. The fewer the number of prints required for ink adhesion, the better the ink adhesion was evaluated. The evaluation was performed according to the evaluation criteria below, and the evaluation results are shown in Tables 1 to 7. [Evaluation Criteria] 1: The number of printed sheets required for ink absorption is 15 or less. 2: The number of prints required for ink transfer exceeds 15 but is 30 or less. 3. The number of printed sheets required for ink to adhere exceeds 30.

[0205] [Table 1]

[0206] [Table 2]

[0207] [Table 3]

[0208] [Table 4]

[0209] [Table 5]

[0210] [Table 6]

[0211] [Table 7]

[0212] From the results in Tables 1 to 7, it can be seen that the positive type lithographic printing plates of each embodiment of this disclosure exhibit good development discrimination and produce high-resolution images, and the resulting lithographic printing plates have excellent print resistance and scratch resistance. The results from Example 2 show that the use of propyl gallate, the specific compound (a-2), yields good results. Furthermore, the results from Examples 2 to 6 indicate that good results can be obtained regardless of the content of the specific compound. Furthermore, a comparison of Example 2 with Examples 21, 22 to 26 shows that using a fluorine-based surfactant or a siloxane-based surface modifier, or surfactant, and especially using a fluorine-based surfactant or a siloxane-based surfactant and a siloxane-based surface modifier (e-2) in the upper layer, results in particularly better development discrimination and scratch resistance. A comparison of Comparative Examples 2 to 7 with each of the Examples shows that, even with compounds having a phenolic hydroxyl group in one molecule, each of the Examples exhibits better development discrimination, print durability of the print plate, and scratch resistance of the image area compared to a positive-type lithographic printing plate master plate having an image recording layer made of a positive-type photosensitive resin composition using a compound without an electron-withdrawing group or a compound having an electron-withdrawing group other than a specific electron-withdrawing group.

[0213] [Examples 28-55, Comparative Examples 12-22] In Example 1, except that the lower layer forming coating composition (III) was replaced with the lower layer forming coating composition (II) described below, a lithographic printing plate of Example 28 was obtained in the same manner and evaluated in the same manner as in Example 1. In addition, lithographic printing plates of Examples 28 to 55 and Comparative Examples 12 to 22 were prepared, containing the formulations of the lower layer forming coating composition (III) and the upper layer forming coating composition (II) according to the types and amounts described in Tables 8 to 14 below. In Tables 8 to 14, the values ​​for content represent parts by mass, and "-" indicates that the compound is not present. The same evaluations as in Example 1 were performed using the lithographic printing plates obtained for each example and comparative example. The results are shown in Tables 8 to 14 below.

[0214] [Coating liquid composition for forming the lower layer (III)] N-(4-aminosulfonylphenyl)methacrylamide / acrylonitrile / methyl methacrylate copolymer (copolymerization ratio: 32 / 36 / 32: weight-average molecular weight 50000): 2.5 parts m,p-cresol novolac: 0.4 parts • Specific compounds or comparative compounds with the following structure (compounds listed in Tables 8 to 14): In the amounts listed in Tables 8 to 14 • Infrared absorber (IR dye (I): structure shown below): 0.2 parts • Tetrahydrophthalic anhydride (THPA): 0.3 parts or none (as listed in Tables 8-14) • p-toluenesulfonic acid (p-TsO): 0.02 parts or not present (as listed in Tables 8 to 14) · 3-Methoxy-4-diazodiphenylamine hexafluorophosphate: 0.1 part • Ethyl violet with the counterion replaced by 6-hydroxynaphthalenesulfonic acid: 0.15 parts • Fluorine-based surfactant (Megafac F-780F, DIC Corporation, see structure (e-1)): 0.01 parts • Silicone-based surface modifier (BYK-300, BYK Japan Co., Ltd.): 0.01 parts or not included (as listed in Tables 8 to 14) • Siloxane-based surface modifier (additive (e-2): 0.01 part or not included (as listed in Tables 8 to 14)) Methyl ethyl ketone: 30 parts 1-Methoxy-2-propanol: 15 parts • γ-butyrolactone: 15 parts

[0215] [Table 8]

[0216] [Table 9]

[0217] [Table 10]

[0218] [Table 11]

[0219] [Table 12]

[0220] [Table 13]

[0221] [Table 14]

[0222] The results in Tables 8 to 14 show that the positive type lithographic printing plates of each embodiment of this disclosure exhibit good development discrimination and produce high-resolution images, and the resulting lithographic printing plates have excellent print resistance and scratch resistance. The results from Example 29 show that the use of propyl gallate, the specific compound (a-2), yields good results. Furthermore, the results from Examples 29 to 33 indicate that good results can be obtained regardless of the content of the specific compound. A comparison of Example 29 with Examples 49 and 50-54 shows that using a fluorine-based surfactant or a siloxane-based surface modifier, or a surfactant, and further using a siloxane-based surface modifier (e-2) in combination, results in particularly better development discrimination and scratch resistance. A comparison of Comparative Examples 13 to 16 with each of the Examples shows that, even with compounds having a phenolic hydroxyl group in one molecule, each of the Examples exhibits better development discrimination, print durability of the print plate, and scratch resistance of the image area compared to a positive-type lithographic printing plate master plate having an image recording layer made of a positive-type photosensitive resin composition using a compound without an electron-withdrawing group or a compound having an electron-withdrawing group other than a specific electron-withdrawing group.

Claims

1. Support and The system comprises an image recording layer made of a positive-type photosensitive resin composition formed on the support, The aforementioned positive-type photosensitive resin composition is A compound having at least one electron-withdrawing group and at least one phenolic hydroxyl group in one molecule. Alkali-soluble resins, and Contains an infrared absorber, The aforementioned electron-withdrawing groups are, excluding sulfonyl groups, Positive planographic printing plate original plate.

2. The positive type lithographic printing plate master according to claim 1, wherein the electron-withdrawing group is at least one selected from the group consisting of a halogen atom, a trifluoromethyl group, a nitro group, a cyano group, an alkoxycarbonyl group, an acyloxy group, an amide group, and an alkylcarbonyl group.

3. The compound having at least one electron-withdrawing group and at least one phenolic hydroxyl group in one molecule is a compound having two or more phenolic hydroxyl groups in one molecule, according to claim 1 or claim 2.

4. The compound having at least one electron-withdrawing group and at least one phenolic hydroxyl group in one molecule is a compound having three or more phenolic hydroxyl groups in one molecule, as described in claim 1 or claim 2.

5. The positive type lithographic printing plate master according to claim 1 or claim 2, wherein the electron-withdrawing group is an alkoxycarbonyl group or an alkylcarbonyl group.

6. The compound having at least one electron-withdrawing group and at least one phenolic hydroxyl group in one molecule includes compounds selected from the group consisting of gallic acid ester compounds and compounds having multiple gallic acid ester moieties in the same molecule, according to claim 1 or claim 2.

7. The compound having at least one electron-withdrawing group and at least one phenolic hydroxyl group in one molecule is a gallic acid ester compound, as described in claim 1 or claim 2.

8. The image recording layer is an image recording layer having a lower layer and an upper layer in that order from the support side, and at least one of the lower layer and the upper layer is made of the positive type photosensitive resin composition, as described in claim 1 or claim 2.

9. The positive type lithographic printing plate according to claim 8, wherein the plate has an undercoat layer between the support and the image recording layer.

10. The lower layer consists of the positive-type photosensitive resin composition, The alkali-soluble resin contained in the lower layer comprises at least one selected from the group consisting of an acrylic resin having a sulfonamide group in its side chain, an acrylic resin having a phenolic hydroxyl group in its side chain, and a novolac resin, as described in claim 8.

11. The upper layer is the positive-type photosensitive resin composition, The upper layer comprises an infrared absorbent and a water-insoluble and alkali-soluble resin, wherein the water-insoluble and alkali-soluble resin is at least one selected from the group consisting of polyamide resin, epoxy resin, polyacetal resin, acrylic resin, methacrylic resin, polystyrene resin, and novolac-type phenolic resin. The positive type lithographic printing plate according to claim 8, wherein an interaction is formed between the polar groups of the water-insoluble and alkali-soluble resin and the infrared absorber.

12. The positive type lithographic printing plate according to claim 9, wherein the undercoat layer comprises at least one selected from the group consisting of phosphonic acid having an amino group, organic phosphonic acid, organic phosphoric acid, organic phosphinic acid, amino acid, and hydrochloride salt of an amine having a hydroxyl group.

13. The positive type lithographic printing plate according to claim 8, wherein the upper layer further comprises a polymer having a structural unit having an alkyl fluoride in its side chain.

14. The positive type lithographic printing plate according to claim 8, wherein at least one of the upper layer and the lower layer contains a polymer having a constituent unit represented by the following formula (I). 【Chemistry 1】 In formula (I), R １１ and R １２ Each of these independently represents a hydrogen atom or an alkyl group, R １３ represents a hydrogen atom or a monovalent substituent, L １１ and L １２ Each of these independently represents a single bond or a divalent linking group, and Rh represents a substituent containing two or more silicon atoms.

15. The positive type lithographic printing plate according to claim 8, wherein the upper layer comprises a polymer having a constituent unit represented by formula (I).

16. An exposure step for image exposure of a positive type lithographic printing plate according to claim 1 or claim 2, and The process includes, in this order, a developing step in which the exposed positive type lithographic printing plate is developed using an alkaline aqueous solution with a pH of 8.5 to 13.

5. Method for producing lithographic printing plates.

17. An exposure step for image exposure of a positive type lithographic printing plate master according to claim 8, and The process includes, in this order, a developing step in which the exposed positive type lithographic printing plate is developed using an alkaline aqueous solution with a pH of 8.5 to 13.

5. Method for producing lithographic printing plates.

Images