CN112512826B

CN112512826B - On-press developable lithographic printing plate precursor, method for producing lithographic printing plate, and lithographic printing method

Info

Publication number: CN112512826B
Application number: CN201980050876.8A
Authority: CN
Inventors: 工藤康太郎; 荒木健次郎
Original assignee: Fujifilm Corp
Current assignee: Fujifilm Corp
Priority date: 2018-07-30
Filing date: 2019-07-29
Publication date: 2022-10-21
Anticipated expiration: 2039-07-29
Also published as: JPWO2020027069A1; WO2020027069A1; JP7064595B2; CN112512826A

Abstract

The invention provides an on-press development type lithographic printing plate precursor, a method for manufacturing a lithographic printing plate using the on-press development type lithographic printing plate precursor, and a lithographic printing method using the on-press development type lithographic printing plate precursor, wherein the on-press development type lithographic printing plate precursor comprises a support, an image recording layer and an overcoat layer in this order, the image recording layer comprises a binder polymer and a development accelerator, the binder polymer comprises a structural unit formed from an aromatic vinyl compound and a structural unit formed from an acrylonitrile compound, the development accelerator has a polarity term of SP value of 6.0 to 26.0, and the overcoat layer has a film thickness thicker than that of the image recording layer.

Description

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

Technical Field

The present invention relates to an on-press developable lithographic printing plate precursor, a method for producing a lithographic printing plate, and a lithographic printing method.

Background

In general, a lithographic printing plate is composed of an oleophilic image portion that accepts ink during printing and a hydrophilic non-image portion that accepts fountain solution. Lithographic printing is a method of printing by using the property of water and oil-based ink repelling each other, in which a difference in ink adhesion occurs on the surface of a lithographic printing plate by using an oleophilic image portion of the lithographic printing plate as an ink-receiving portion and a hydrophilic non-image portion as a fountain solution-receiving portion (ink-non-receiving portion), and after ink is applied only to the image portion, the ink is transferred onto a printing object such as paper.

In order to produce such a lithographic printing plate, a lithographic printing plate precursor (PS plate) in which an oleophilic photosensitive resin layer (image recording layer) is provided on a hydrophilic support has been widely used. In general, a lithographic printing plate is obtained by exposing an original image such as a high contrast film to light, leaving a portion of the image portion to be an image recording layer, removing the remaining unnecessary image recording layer by dissolving it in an alkaline developer or an organic solvent to expose the surface of a hydrophilic support, and performing plate making by a method of forming a non-image portion.

Further, since the global environment is being increasingly concerned, environmental problems associated with waste liquid accompanying wet treatment such as development treatment become apparent.

In order to solve the above environmental problems, development and plate making have been simplified and have not been treated. As one of the simple manufacturing methods, a method called "on-press development" is performed. That is, a method is used in which after exposure of a lithographic printing plate precursor, the lithographic printing plate precursor is directly mounted on a printing press without conventional development, and unnecessary portions of an image recording layer are removed at an initial stage of a normal printing process.

In the present invention, a lithographic printing plate precursor that can be used for such on-press development is referred to as an "on-press development type lithographic printing plate precursor".

As conventional lithographic printing plate precursors or printing methods using lithographic printing plate precursors, for example, the contents described in patent documents 1 to 3 can be cited.

Patent document 1 describes a negative-working lithographic printing plate precursor having a support and an image-recording layer containing a compound having a repeating unit represented by the following general formula (1) and a radical polymerization initiator.

[ chemical formula 1]

General formula (1)

In the general formula (1), A represents a single bond or a divalent linking group. Ar represents a benzene nucleus or a naphthalene nucleus. R is ¹ Represents a hydroxyl group, an alkyl group or an aryl group. i represents an integer of 0 to 3. When i represents an integer of 2 or more, a plurality of R's are present ¹ May be the same or different. R ² Represents a hydrogen atom, an alkyl group or an aryl group. L represents-O-, OCO-, or-OCONH-. * Indicates a site bonded to Ar. * Denotes a site bonded to Y. Y represents a (m + 1) -valent linking group. X represents a (meth) acryloyloxy group.

1 represents an integer of 0 or 1. m represents an integer of 1 or 2. Wherein, in the case where 1 is 0, m is 1.n represents an integer of 1 or 2.

Patent document 2 describes an image-forming element including a substrate having thereon an image-forming layer containing a radical polymerizable component, an initiator composition, an infrared absorbing cyanine dye having a methine chain connecting heterocyclic groups (wherein the methine chain has a chain length of at least 7 carbon atoms), and a primary polymer binder, and an overcoat layer disposed on the image-forming layer, the overcoat layer being mainly composed of poly (vinyl alcohol) having a degree of hydrolysis of 85% or less, wherein the initiator composition is capable of generating radicals sufficient to initiate polymerization of the radical polymerizable groups by exposure to an image-forming radiation and contains diaryliodonium borate.

Patent document 3 describes a negative-working lithographic printing plate precursor comprising: a substrate; a negative image forming layer disposed on the substrate and including a radical polymerizable component, an initiator composition capable of generating radicals when exposed to imaging radiation light, a radiation light absorber, and a polymer binder; and an outermost water-soluble overcoat layer disposed directly on the negative image-forming layer and comprising (1) one or more film-forming water-soluble polymer binders present and (2) organic paraffin particles dispersed in the one or more film-forming water-soluble polymer binders in an amount of at least 1.3 wt% and at most 60 wt% based on the total outermost water-soluble overcoat layer weight, wherein the organic paraffin particles have an average maximum dimension of at least 0.05 μm and at most 0.7 μm as measured from a scanning electron micrograph of the dried outermost water-soluble overcoat layer.

Patent document 1: japanese patent laid-open publication No. 2017-132227

Patent document 2: japanese Kohyo publication No. 2010-529490

Patent document 3: japanese laid-open patent publication No. 2015-519610

Disclosure of Invention

Technical problem to be solved by the invention

In the on-press development, development residue (on-press development residue) may be generated.

When such on-press development residue is generated, it becomes a cause of occurrence of printing stain or the like due to stain of a fountain solution or stain of a non-image portion, and therefore, in the field of lithographic printing plate precursors, there is a demand for on-press development type lithographic printing plate precursors in which generation of on-press development residue is suppressed.

Further, a case where the time from the start of printing on the lithographic printing plate to the adhesion of ink to the printing portion (image portion) is short is referred to as excellent ink-staining property (also simply referred to as "ink-staining property"). In the field of lithographic printing plate precursors, on-press developable lithographic printing plate precursors having excellent ink receptivity are required for reasons such as shortening of the time until the start of printing and suppression of white spots in printed matter.

The present inventors have found that the on-press development type lithographic printing plate precursor according to the present invention (hereinafter, also simply referred to as "lithographic printing plate precursor") suppresses the generation of development residue during on-press development and is excellent in ink adhesion, as compared with the lithographic printing plate precursors described in patent documents 1 to 3.

An object to be solved by one embodiment of the present invention is to provide an on-press developable lithographic printing plate precursor which suppresses the generation of development residue during on-press development and has excellent ink adhesion, a method for producing a lithographic printing plate using the on-press developable lithographic printing plate precursor, and a lithographic printing method using the on-press developable lithographic printing plate precursor.

Means for solving the technical problem

The means for solving the above problems include the following means.

< 1 > an on-press developable lithographic printing plate precursor comprising, in order, a support, an image-recording layer and an overcoat layer,

the image recording layer contains a binder polymer and a development accelerator,

the binder polymer has a structural unit composed of an aromatic vinyl compound and a structural unit composed of an acrylonitrile compound,

the SP value of the developing accelerator has a polarity term value of 6.0 to 26.0,

the overcoat layer has a film thickness larger than that of the image recording layer.

< 2 > the on-press developable lithographic printing plate precursor according to the above < 1 >, wherein the image recording layer further contains a polymerizable compound, and the content of the binder polymer is more than 0 mass% and 400 mass% or less with respect to the total mass of the polymerizable compound.

< 3 > the on-press developable lithographic printing plate precursor according to the above < 1 > or < 2 >, wherein the above overcoat layer comprises a water-soluble polymer.

< 4 > the on-press developable lithographic printing plate precursor according to the above < 3 >, wherein the water-soluble polymer comprises polyvinyl alcohol having a saponification degree of 50% or more.

< 5 > the on-press development type lithographic printing plate precursor according to any one of the above < 1 > to < 4 >, wherein the above development accelerator is a compound having a cyclic structure.

< 6 > the on-press developable lithographic printing plate precursor according to the above < 5 >, wherein the compound having a cyclic structure has a hydroxyl group.

< 7 > the on-press development type lithographic printing plate precursor according to any one of the above < 1 > to < 6 >, wherein the above development accelerator is an onium compound.

< 8 > the on-press developable lithographic printing plate precursor according to any one of the above < 1 > to < 7 > containing two or more compounds as the above-mentioned development accelerator.

< 9 > the on-press developable lithographic printing plate precursor according to any one of the above < 1 > to < 8 >, wherein the above binder polymer further has a structural unit formed from N-vinylpyrrolidone.

< 10 > the on-press developable lithographic printing plate precursor according to any one of the above < 1 > to < 9 >, wherein the above image recording layer further comprises an infrared absorber.

< 11 > the on-press developable lithographic printing plate precursor according to the above < 10 >, wherein the infrared absorber is an infrared absorber decomposed by infrared exposure.

< 12 > the on-press developable lithographic printing plate precursor according to the above < 10 > or < 11 >, wherein the infrared absorber is an infrared absorber decomposed by heat, electron movement or both of the heat and the electron movement caused by infrared exposure.

< 13 > the on-press developable lithographic printing plate precursor according to any one of the above < 10 > to < 12 >, wherein the infrared absorber is a cyanine dye.

< 14 > the on-press developable lithographic printing plate precursor according to any one of the above < 10 > to < 113 >, wherein the infrared absorber is a compound represented by the following formula 1.

[ chemical formula 2]

In the formula 1, R ¹ Represents R by infrared ray exposure ¹ -L bond-breaking group, R ₁₁ ～R ₁₈ Each independently represents a hydrogen atom, a halogen atom, -Ra, -ORb, -SRc or-NRdRe, and Ra to Re are each independentlyAlkyl group A ₁ 、A ₂ And a plurality of R ₁₁ ～R ₁₈ May be linked to form a monocyclic or polycyclic ring, A ₁ And A ₂ Each independently represents an oxygen atom, a sulfur atom or a nitrogen atom, n ₁₁ And n ₁₂ Each independently represents an integer of 0 to 5, wherein n ₁₁ And n ₁₂ Is 2 or more in total, n ₁₃ And n ₁₄ Each independently represents 0 or 1, L represents an oxygen atom, a sulfur atom or-NR ¹⁰ -，R ¹⁰ Represents a hydrogen atom, an alkyl group or an aryl group, and Za represents a counter ion for neutralizing a charge.

< 15 > the on-press developable lithographic printing plate precursor according to the above < 14 >, wherein R in the above formula 1 ¹ Is a group represented by the following formula 2.

[ chemical formula 3]

In the formula 2, R ^Z Represents an alkyl group, and the wavy line moiety represents a bonding site with a group represented by L in the above formula 1.

< 16 > a method for making a lithographic printing plate comprising: image-wise exposing the on-press development type lithographic printing plate precursor described in any one of the above-mentioned < 1 > to < 15 >; and

and a step of removing the image recording layer of the non-image portion on the printing press by supplying at least one selected from the group consisting of printing ink and dampening solution.

< 17 > a lithographic method comprising: image-wise exposing the on-press development type lithographic printing plate precursor described in any of the above < 1 > to < 15 >;

a step of supplying at least one selected from the group consisting of printing ink and dampening solution to remove the image recording layer of the non-image portion on the printing press to produce a lithographic printing plate; and

and a step of printing by the obtained lithographic printing plate.

Effects of the invention

According to an embodiment of the present invention, it is possible to provide an on-press development type lithographic printing plate precursor in which development residue is suppressed from being generated during on-press development and which is excellent in ink adhesion, a method for manufacturing a lithographic printing plate using the on-press development type lithographic printing plate precursor, and a lithographic printing method using the on-press development type lithographic printing plate precursor.

Detailed Description

The present invention will be described in detail below. The following description of the constituent elements is made in accordance with the exemplary embodiments of the present invention, but the present invention is not limited to such embodiments.

In the present specification, "to" indicating a numerical range is used to include numerical values described before and after the range as a lower limit value and an upper limit value.

Also, in the expression of a group (atomic group) in the present specification, the expression not labeled with substituted and unsubstituted includes a group having no substituent, and also includes a group having a substituent. For example, "alkyl group" includes not only an alkyl group having no substituent (unsubstituted alkyl group) but also an alkyl group having a substituent (substituted alkyl group).

In the present specification, "(meth) acrylic acid" is a term used as a concept including both acrylic acid and methacrylic acid, and "(meth) acryloyl group" is a term used as a concept including both acryloyl group and methacryloyl group.

The term "step" in the present specification includes not only an independent step but also a step that can achieve the intended purpose of the step even when the step cannot be clearly distinguished from other steps. In the present invention, "mass%" means the same as "wt%", and "parts by mass" means the same as "parts by weight".

In the present invention, unless otherwise specified, each component in the composition or each structural unit in the polymer may be contained singly or two or more kinds may be used simultaneously.

Further, in the present invention, in the case where there are a plurality of substances or structural units corresponding to each component in the composition or each structural unit in the polymer, unless otherwise specified, the amount of each structural unit in each component or polymer in the composition means the total amount of the corresponding plurality of substances present in the composition or the corresponding plurality of each structural units present in the polymer.

In the present invention, a combination of 2 or more preferred embodiments is a more preferred embodiment.

The weight average molecular weight (Mw) and the number average molecular weight (Mn) in the present invention are, unless otherwise specified, molecular weights obtained by detection with a solvent THF (tetrahydrofuran), a differential refractometer and conversion using polystyrene as a standard substance by a Gel Permeation Chromatography (GPC) analyzer of a column using TSKgel GMHxL, TSKgel G4000HxL and TSKgel G2000HxL (each product name manufactured by TOSOH CORPORATION).

In the present invention, the term "lithographic printing plate precursor" includes not only lithographic printing plate precursors but also waste plate precursors. The term "lithographic printing plate" includes not only a lithographic printing plate produced by exposing and developing a lithographic printing plate precursor as necessary, but also a waste plate. In the case of a waste plate precursor, the operations of exposure and development are not necessarily required. The waste plate is, for example, a lithographic printing plate precursor to be mounted on an unused plate cylinder when printing is performed on a part of a paper surface in a single color or two colors in a color newspaper printing.

In the present invention, an "" in the chemical structural formula represents a bonding position with another structure.

The present invention will be described in detail below.

(original plate of lithographic printing plate of on-press development type)

The on-press development type lithographic printing plate precursor of the present invention comprises a support, an image recording layer and an overcoat layer in this order, wherein the image recording layer comprises a binder polymer and a development accelerator, the binder polymer comprises a structural unit comprising an aromatic vinyl compound and a structural unit comprising an acrylonitrile compound, the polarity term of the SP value of the development accelerator has a value of 6.0 to 26.0, and the film thickness of the overcoat layer is thicker than the film thickness of the image recording layer.

As a result of intensive studies, the present inventors have found that a lithographic printing plate precursor having excellent on-press developability and suppressed development residue during on-press development can be provided by adopting the above-described structure.

The detailed mechanism by which the above-described effects can be obtained is not clear, but is presumed as follows.

In the field of on-press development type lithographic printing plate precursors, it is known to use a development accelerator in the image recording layer in order to improve on-press developability.

The present inventors have found that when a development accelerator is added only to an image recording layer, water is injected into a printing plate precursor or the like, and the components of the image recording layer are dissolved in water, which may easily cause development residue.

As a result of intensive studies, the present inventors have found that the development residue can be suppressed from being generated by providing an overcoat layer on the image recording layer.

The present inventors have also found that, when a topcoat layer is provided and a development accelerator having an SP value with a polarity term of 6.0 to 26.0 (hereinafter, also referred to as "specific development accelerator") is used, the ink adhesion during printing may be reduced.

Accordingly, the present inventors have conducted extensive studies and found that the ink receptivity of an ink can be improved by using a binder polymer having a structural unit composed of an aromatic vinyl compound and a structural unit composed of an acrylonitrile compound (hereinafter, also referred to as a "specific binder polymer").

As described above, the on-press developable lithographic printing plate precursor according to the present invention is based on a novel finding that by combining a specific development accelerator, a topcoat layer, and a specific binder polymer, it is possible to exhibit excellent effects such as suppression of development residue and improvement of ink receptivity at the same time.

The lithographic printing plate precursor described in patent document 1 or 2 does not contain a specific binder polymer, and there is room for further improvement in terms of improvement in ink receptivity.

The lithographic printing plate precursor described in patent document 3 is neither described nor suggested for an overcoat layer having a film thickness thicker than that of the image recording layer, and is poor in the inhibition of development residue.

Further, it is considered that a lithographic printing plate excellent in on-press developability can be easily obtained from the lithographic printing plate precursor according to the present invention. This is presumed to be based on the results of effects obtained by including a specific development accelerator, effects based on the non-image portion being easily removed by adhering to an ink roller at the time of on-press development by including a specific binder polymer (ink tack development), synergistic effects with the specific development accelerator, the specific binder polymer, and the above-described overcoat layer, and the like.

Further, it is considered that a lithographic printing plate precursor excellent in scratch resistance can be easily obtained from the lithographic printing plate precursor according to the present invention. This is presumed to be based on the effect of having the above-described overcoat layer and the like.

< support body >

The lithographic printing plate precursor of the present invention has a support.

As the support, a support having a hydrophilic surface (also referred to as "hydrophilic support") is preferable. As the hydrophilic surface, a surface having a contact angle with water of less than 10 ° is preferable, and a surface having a contact angle with water of less than 5 ° is more preferable.

The water contact angle in the present invention was measured as a contact angle of a water droplet on a surface at 25 ℃ (after 0.2 sec) by DM-501 manufactured by Kyowa Interface Science co.

The support for the lithographic printing plate precursor according to the present invention can be appropriately selected from known supports for lithographic printing plate precursors and used. The support is preferably an aluminum plate which has been subjected to roughening treatment by a known method and to anodic oxidation treatment.

The aluminum plate may be further subjected to a surface hydrophilization treatment based on an alkali metal silicate as described in each of the specifications of U.S. Pat. nos. 2,714,066, 3,181,461, 3,280,734 and 3,902,734, or a surface hydrophilization treatment based on a polyvinylphosphonic acid or the like as described in each of the specifications of U.S. Pat. nos. 3,276,868, 4,153,461 and 4,689,272, as appropriate and selectively selected as necessary, and the pore enlargement treatment and the pore sealing treatment of the anodic oxide film described in japanese patent application laid-open nos. 2001-253181 and 2001-322365 are performed.

The center line average roughness of the support is preferably 0.10 to 1.2. Mu.m.

The support may have a back coating layer containing an organic polymer compound described in Japanese patent application laid-open No. 5-045885, a silicon alkoxide compound described in Japanese patent application laid-open No. 6-035174, or the like on the surface opposite to the image recording layer, as necessary.

< image recording layer >

The lithographic printing plate precursor according to the present invention has an image recording layer formed on a support.

The image recording layer used in the present invention preferably further contains a polymerizable compound from the viewpoint of brush resistance and photosensitivity.

From the viewpoint of brush resistance and photosensitivity, the image recording layer used in the present invention preferably further contains an electron-accepting polymerization initiator.

From the viewpoint of brush resistance and photosensitivity, the image recording layer used in the present invention preferably further contains an electron donating polymerization initiator.

The image recording layer used in the present invention preferably further contains an infrared absorber from the viewpoint of exposure sensitivity.

The image recording layer used in the present invention may further contain an acid developer in order to confirm exposed portions before development.

From the viewpoint of on-press developability, the lithographic printing plate precursor according to the present invention is preferably capable of removing unexposed portions of the image recording layer by at least one selected from the group consisting of a fountain solution and a printing ink.

The details of each component contained in the image recording layer will be described below.

[ specific development promoters ]

The image recording layer used in the present invention contains a specific development accelerator.

In the present invention, the value of the polarity term of the SP value of the specific development accelerator is 6.0 to 26.0. The value of the polarity term of the SP value is preferably 6.2 to 24.0, more preferably 6.3 to 23.5, and still more preferably 6.4 to 22.0.

SP value (solubility parameter, unit: (cal/cm)) ³ ) ^1/2 ) The value of the polar term δ p in the Hansen (Hansen) solubility parameter is used. The Hansen (Hansen) solubility parameter is a solubility parameter expressed in a three-dimensional space by dividing the solubility parameter introduced by Hildebrand (Hildebrand) into 3 components of a dispersion term δ d, a polar term δ p, and a hydrogen bond term δ h, and in the present invention, the polar term δ p is used.

δp[cal/cm ³ ]Dipole-dipole force term of Hansen solubility parameter, V cm ³ /mol]In molar volume, [ mu ] D]Is the dipole moment. As δ p, the following formula simplified by Hansen and berbourer is generally used.

[ number formula 1]

The specific developing accelerator is not particularly limited as long as the value of the polarity term of the SP value is within the above range, and is preferably a hydrophilic high molecular compound or a hydrophilic low molecular compound.

In the present invention, hydrophilicity means a case where the value of the polarity term of the SP value is 6.0 to 26.0, hydrophilicity high molecular weight compound means a compound having a molecular weight (weight average molecular weight in the case of having a molecular weight distribution) of 3,000 or more, hydrophilicity low molecular weight compound means a compound having a molecular weight (weight average molecular weight in the case of having a molecular weight distribution) of less than 3,000.

Hydrophilic polymer compounds

Examples of the hydrophilic polymer compound include a cellulose compound, and a cellulose compound is preferable.

The cellulose compound includes cellulose and a compound in which at least a part of cellulose is modified (modified cellulose compound), and preferably a modified cellulose compound.

The modified cellulose compound is preferably a compound in which at least a part of the hydroxyl groups of cellulose is substituted with at least one group selected from the group consisting of alkyl groups and hydroxyalkyl groups.

The degree of substitution of the compound in which at least a part of the hydroxyl groups of the cellulose is substituted with at least one group selected from the group consisting of an alkyl group and a hydroxyalkyl group is preferably 0.1 to 6.0, more preferably 1 to 4.

The modified cellulose compound is preferably an alkyl cellulose compound or a hydroxyalkyl cellulose compound, and more preferably a hydroxyalkyl cellulose compound.

As the alkyl cellulose compound, methyl cellulose can be preferably used.

As the hydroxyalkyl cellulose compound, hydroxypropyl cellulose is preferably mentioned.

The molecular weight (weight average molecular weight in the case of having a molecular weight distribution) of the hydrophilic polymer compound is preferably 3,000 to 5,000,000, more preferably 5,000 to 200,000.

Hydrophilic low molecular weight compounds

Examples of the hydrophilic low-molecular compound include an ethylene glycol compound, a polyol compound, an organic amine compound, an organic sulfonic acid compound, an organic sulfamic acid compound, an organic sulfuric acid compound, an organic phosphonic acid compound, an organic carboxylic acid compound, and a betaine compound, and the polyol compound, the organic sulfonic acid compound, and the betaine compound are preferable.

Examples of the ethylene glycol compound include ethylene glycols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, and tripropylene glycol, and ether or ester derivatives of these compounds.

Examples of the polyol compound include glycerol, pentaerythritol, tris (2-hydroxyethyl) isocyanurate, and the like.

Examples of the organic amine compound include triethanolamine, diethanolamine, monoethanolamine, and salts thereof.

Examples of the organic sulfonic acid compound include alkylsulfonic acid, toluenesulfonic acid, benzenesulfonic acid and the like, and salts thereof, and preferable examples thereof include alkylsulfonic acids having an alkyl group of 1 to 10 carbon atoms.

Examples of the organic sulfamic acid compound include alkylaminosulfonic acids and salts thereof.

Examples of the organic sulfuric acid compound include alkyl sulfuric acid, alkyl ether sulfuric acid, and salts thereof.

Examples of the organic phosphonic acid compound include phenylphosphonic acid and salts thereof.

Examples of the organic carboxylic acid compound include tartaric acid, oxalic acid, citric acid, malic acid, lactic acid, gluconic acid, and salts thereof.

Examples of the betaine compound include phosphobetaine compounds, sulfobetaine compounds, carboxybetaine compounds, and the like, and trimethylglycine is preferable.

The molecular weight (weight average molecular weight in the case of having a molecular weight distribution) of the hydrophilic low-molecular compound is preferably 100 or more and less than 3,000, more preferably 300 to 2,500.

-a ring structure-

The specific development accelerator is preferably a compound having a cyclic structure.

The cyclic structure is not particularly limited, and examples thereof include a glucose ring, an isocyanuric ring, an aromatic ring which may have a hetero atom, an aliphatic ring which may have a hetero atom, and the like, in which at least a part of the hydroxyl groups may be substituted.

Examples of the compound having a glucose ring include the cellulose compounds described above.

Examples of the compound having an isocyanuric ring include the tris (2-hydroxyethyl) isocyanurate and the like.

Examples of the compound having an aromatic ring include the above-mentioned toluenesulfonic acid and benzenesulfonic acid.

Examples of the compound having an aliphatic ring include compounds in which the alkyl group is a cyclic structure, and the alkyl group is the alkylsulfuric acid.

The compound having a cyclic structure preferably has a hydroxyl group.

The compound having a hydroxyl group and a cyclic structure preferably includes the cellulose compound and the tris (2-hydroxyethyl) isocyanurate.

Onium compounds

Further, the specific development accelerator is preferably an onium compound.

Examples of the onium compound include an ammonium compound and a sulfonium compound, and an ammonium compound is preferable.

Specific examples of the development accelerator for the onium compound include trimethylglycine and the like.

The onium compound in the electron accepting type polymerization initiator described later is a compound having a polarity term of SP value of 6.0 to 26.0, and is not included in the specific developing accelerator.

Simultaneous use

The image recording layer may contain one specific development accelerator alone, or two or more kinds thereof may be used simultaneously.

One of preferred embodiments of the image recording layer used in the present invention is an embodiment containing two or more compounds as specific development accelerators.

Specifically, from the viewpoint of on-screen developability and ink adhesion, the image recording layer used in the present invention preferably contains the polyol compound and the betaine compound, the betaine compound and the organic sulfonic acid compound, or the polyol compound and the organic sulfonic acid compound as specific development accelerators.

Content-

The content of the specific development accelerator is preferably 0.1% by mass or more and 20% by mass or less, more preferably 0.5% by mass or more and 15% by mass or less, and still more preferably 1% by mass or more and 10% by mass or less, with respect to the total mass of the image recording layer.

[ specific Binder Polymer ]

The image recording layer used in the present invention contains a specific binder polymer.

In the present invention, the specific binder polymer is a binder resin that is not in the form of particles, and the polymer particles described later are not included in the specific binder polymer in the present invention.

The specific binder polymer has a structural unit formed from an aromatic vinyl compound and a structural unit formed from an acrylonitrile compound.

Structural units formed from aromatic vinyl compounds

The specific binder polymer has a structural unit formed of an aromatic vinyl compound.

The aromatic vinyl compound may be a compound having a structure in which an aromatic ring is bonded to a vinyl group, and examples thereof include a styrene compound and a vinylnaphthalene compound, and a styrene compound is preferable, and styrene is more preferable.

The styrene compound includes styrene, p-methylstyrene, p-methoxystyrene, β -methylstyrene, p-methyl- β -methylstyrene, α -methylstyrene and p-methoxy- β -methylstyrene, and styrene is preferably used.

Examples of the vinylnaphthalene compound include 1-vinylnaphthalene, methyl-1-vinylnaphthalene,. Beta. -methyl-1-vinylnaphthalene, 4-methyl-1-vinylnaphthalene, and 4-methoxy-1-vinylnaphthalene, and 1-vinylnaphthalene is preferably used.

Further, as the structural unit formed of an aromatic vinyl compound, a structural unit represented by the following formula A1 can be preferably mentioned.

[ chemical formula 4]

In the formula A1, R ^A1 、R ^A2 And R ^A2’ Each independently represents a hydrogen atom or an alkyl group, ar represents an aromatic ring group, R ^A3 Represents a substituent, and n represents an integer not more than the maximum number of substituents of Ar.

In the formula A1, R ^A1 、R ^A2 And R ^A2’ Each independently is preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, more preferably a hydrogen atom or a methyl group, and still more preferably a hydrogen atom.

In formula A1, ar is preferably a benzene ring or a naphthalene ring, and more preferably a benzene ring.

In the formula A1, R ^A3 Preferably an alkyl group or an alkoxy group, more preferably an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, and still more preferably a methyl group or a methoxy group.

In the formula A1, in the presence of a plurality of R ^A3 In the case of (2), a plurality of R ^A3 May be the same or different.

In formula A1, n is preferably an integer of 0 to 2, more preferably 0 or 1, and even more preferably 0.

The content of the structural unit formed from an aromatic vinyl compound in the specific binder polymer is preferably 1 to 80% by mass, and more preferably 5 to 60% by mass, based on the total mass of the specific binder polymer.

Structural units formed from acrylonitrile compounds

The specific binder polymer has a structural unit formed of an acrylonitrile compound.

The acrylonitrile compound includes (meth) acrylonitrile and the like, and acrylonitrile is preferably used.

Further, as the structural unit formed of an acrylonitrile compound, a structural unit represented by the following formula B1 can be preferably mentioned.

[ chemical formula 5]

In the formula B1, R ^B1 Represents a hydrogen atom or an alkyl group.

In the formula B1, R ^B1 A hydrogen atom or an alkyl group having 1 to 4 carbon atoms is preferable, a hydrogen atom or a methyl group is more preferable, and a hydrogen atom is even more preferable.

The content of the structural unit composed of an acrylonitrile compound in the specific binder polymer is preferably 1 to 80% by mass, and more preferably 5 to 60% by mass, based on the total mass of the specific binder polymer.

Structural units formed from N-vinyl heterocyclic compounds

From the viewpoint of brush resistance and chemical resistance, the specific binder polymer preferably further has a structural unit formed of an N-vinyl heterocyclic compound.

Examples of the N-vinyl heterocyclic compound include N-vinylpyrrolidone, N-vinylcarbazole, N-vinylpyrrole, N-vinylphenothiazine, N-vinylsuccinimide, N-vinylphthalimide, N-vinylcaprolactam and N-vinylimidazole, and N-vinylpyrrolidone is preferable.

Further, as the structural unit formed of the N-vinyl heterocyclic compound, a structural unit represented by the following formula C1 can be preferably mentioned.

[ chemical formula 6]

In the formula C1, ar ^N Represents a heterocyclic structure containing a nitrogen atom, ar ^N The nitrogen atom in (b) is bonded to the carbon atom represented by.

In the formula C1, from Ar ^N The heterocyclic structure represented by (a) is preferably a pyrrolidone ring, a carbazole ring, a pyrrole ring, a phenothiazine ring, a succinimide ring, a phthalimide ring, a caprolactam ring, or an imidazole ring, and more preferably a pyrrolidone ring.

And, from Ar ^N The heterocyclic structure shown may have a known substituent.

The content of the structural unit formed of the N-vinyl heterocyclic compound in the specific binder polymer is preferably 1 to 80% by mass, and more preferably 5 to 60% by mass, based on the total mass of the specific binder polymer.

Structural units having ethylenically unsaturated groups

The specific binder polymer may also have a structural unit having an ethylenically unsaturated group.

The ethylenically unsaturated group is not particularly limited, and examples thereof include a vinyl group, an allyl group, a vinylphenyl group, a (meth) acrylamide group, and a (meth) acryloyloxy group, and from the viewpoint of reactivity, a (meth) acryloyloxy group is preferable.

The structural unit having an ethylenically unsaturated group can be introduced into a specific binder polymer by high-molecular reaction or copolymerization. Specifically, the introduction can be carried out, for example, by a method in which a compound having an epoxy group and an ethylenically unsaturated group (for example, glycidyl methacrylate or the like) is reacted with a polymer into which a structural unit having a carboxyl group such as methacrylic acid or the like is introduced, a method in which a compound having an isocyanate group and an ethylenically unsaturated group (2-isocyanatoethyl methacrylate or the like) is reacted with a polymer into which a structural unit having a group having an active hydrogen such as a hydroxyl group is introduced, or the like.

The structural unit having an ethylenically unsaturated group can be introduced into the specific binder polymer by a method such as reacting a compound having a carboxyl group and an ethylenically unsaturated group with a polymer into which a structural unit having an epoxy group such as glycidyl (meth) acrylate is introduced.

Further, the structural unit having an ethylenically unsaturated group can be introduced into a specific binder polymer by using, for example, a monomer containing a partial structure represented by the following formula d1 or the following formula d 2. Specifically, for example, after polymerization is performed using at least the above-mentioned monomer, a partial structure represented by the following formula d1 or the following formula d2 is subjected to a release reaction using a basic compound to form an ethylenically unsaturated group, whereby a structural unit having an ethylenically unsaturated group is introduced into a specific binder polymer.

[ chemical formula 7]

In the formulae d1 and d2, R ^d Represents a hydrogen atom or an alkyl group, A ^d Represents a halogen atom, X ^d represents-O-or-NR ^N -，R ^N Represents a hydrogen atom or an alkyl group, and represents a bonding site with another structure.

In the formulae d1 and d2, R ^d Preferably a hydrogen atom or a methyl group.

In the formulae d1 and d2, A ^d Preferably a chlorine atom, a bromine atom or an iodine atom.

In the formulae d1 and d2, X ^d preferably-O-. At X ^d represents-NR ^N In the case of-R ^N Preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and more preferably a hydrogen atom.

Examples of the structural unit having an ethylenically unsaturated group include structural units represented by the following formula D1.

[ chemical formula 8]

In the formula D1, L ^D1 Represents a single bond or a divalent linking group, L ^D2 Represents a m +1 valent linking group, X ^D1 And X ^D2 Each independently represents-O-or-NR ^N -，R ^N Represents a hydrogen atom or an alkyl group, R ^D1 And R ^D2 Each independently represents a hydrogen atom or a methyl group, and m represents an integer of 1 or more.

In the formula D1, L ^D1 Preferably a single bond. At L ^D1 When a divalent linking group is represented, it is preferably an alkylene group, an arylene group, or a divalent group in which 2 or more of these groups are bonded, and more preferably an alkylene group or a phenylene group having 2 to 10 carbon atoms.

In the formula D1, L ^D2 A group represented by any one of the following formulae D2 to D6 is preferable.

In the formula D1, X ^D1 And X ^D2 Are preferably-O-. And, in X ^D1 And X ^D2 At least one of (A) represents-NR ^N In the case of-R ^N Preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and more preferably a hydrogen atom.

In the formula D1, R ^D1 Preferably methyl.

In the formula D1, m are R ^D2 At least one of them is preferably methyl.

In the formula D1, m is preferably an integer of 1 to 4, more preferably 1 or 2, and further preferably 1.

[ chemical formula 9]

In the formulae D2 to D6, L ^D3 ～L ^D7 Represents a divalent linking group, L ^D5 And L ^D6 May be different from X in formula D1 ^D1 The wavy line represents the bonding site with X in the formula D1 ^D2 The bonding site of (3).

In the formula D3, L ^D3 Preferably an alkylene group, an arylene group or a group in which 2 or more of these are bonded, and more preferably an alkylene group or a phenylene group having 1 to 10 carbon atoms or a group in which 2 or more of these are bonded.

In the formula D4, L ^D4 Preferably an alkylene group, an arylene group, or a group in which 2 or more of these are bonded, and more preferably an alkylene group having 1 to 10 carbon atoms, a phenylene group, or a group in which 2 or more of these are bonded.

In the formula D5, L ^D5 Preferably an alkylene group, an arylene group, or a group in which 2 or more of these are bonded, and more preferably an alkylene group having 1 to 10 carbon atoms, a phenylene group, or a group in which 2 or more of these are bonded.

In the formula D5, L ^D6 Preferably an alkylene group, an arylene group or a group in which 2 or more of these groups are bonded, more preferably carbonAn alkylene group having 1 to 10 atoms, a phenylene group, or a group in which 2 or more of these groups are bonded.

In the formula D6, L ^D7 Preferably an alkylene group, an arylene group or a group in which 2 or more of these are bonded, and more preferably an alkylene group or a phenylene group having 1 to 10 carbon atoms or a group in which 2 or more of these are bonded.

Specific examples of the structural unit having an ethylenically unsaturated group are shown below, but the structural unit having an ethylenically unsaturated group contained in the binder polymer according to the present invention is not limited thereto. In the following specific examples, R represents a hydrogen atom or a methyl group, respectively.

[ chemical formula 10]

The content of the structural unit having an ethylenically unsaturated group in the specific binder polymer is preferably 1 to 80% by mass, and more preferably 5 to 60% by mass, with respect to the total mass of the specific binder polymer.

Structural units having acidic groups-

The specific binder polymer may contain a structural unit having an acidic group, and preferably does not contain a structural unit having an acidic group from the viewpoint of on-press developability and ink-receptivity.

Specifically, the content of the structural unit having an acidic group in the specific binder polymer is preferably 60% by mass or less, more preferably 50% by mass or less, and still more preferably 40% by mass or less. The lower limit of the content is not particularly limited, and may be 0 mass%.

The acid value of the specific binder polymer is preferably 20mgKOH/g or less, more preferably 50mgKOH/g or less, and still more preferably 100mgKOH/g or less. The lower limit of the acid value is not particularly limited, and may be 0mgKOH/g.

In the present invention, the acid value can be determined by a method based on JIS K0070:1992, etc.

Structural units having hydrophobic groups

From the viewpoint of ink-stainability, the specific binder polymer may contain a structural unit containing a hydrophobic group.

Examples of the hydrophobic group include an alkyl group, an aryl group, and an aralkyl group.

The structural unit containing a hydrophobic group is preferably a structural unit formed from an alkyl (meth) acrylate compound, an aryl (meth) acrylate compound, or an arylalkyl (meth) acrylate compound, and more preferably a structural unit formed from an alkyl (meth) acrylate compound.

The alkyl group in the alkyl (meth) acrylate compound preferably has 1 to 10 carbon atoms. The alkyl group may be linear or branched, and may have a cyclic structure. Examples of the alkyl (meth) acrylate compound include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and dicyclopentyl (meth) acrylate.

The aryl group in the aryl (meth) acrylate compound preferably has 6 to 20 carbon atoms, and more preferably a phenyl group. The aryl group may have a known substituent. The aryl (meth) acrylate compound is preferably phenyl (meth) acrylate.

The alkyl group in the arylalkyl (meth) acrylate compound preferably has 1 to 10 carbon atoms. The alkyl group may be linear or branched, and may have a cyclic structure. The aryl group in the arylalkyl (meth) acrylate compound preferably has 6 to 20 carbon atoms, and more preferably a phenyl group. As the arylalkyl (meth) acrylate compound, benzyl (meth) acrylate is preferably mentioned.

The content of the structural unit having a hydrophobic group in the specific binder polymer is preferably 1 to 80% by mass, and more preferably 5 to 60% by mass, with respect to the total mass of the specific binder polymer.

Structural units having hydrophilic groups

From the viewpoint of improving the brush resistance, chemical resistance, and on-press developability, the specific binder polymer may contain a structural unit having a hydrophilic group.

Examples of the hydrophilic group include-OH, -CN and-CONR ¹ R ² 、-NR ² COR ¹ (R ¹ 、R ² Each independently represents a hydrogen atom, an alkyl group, an alkenyl group or an aryl group. R ¹ And R ² May be bonded to form a ring. ) -NR ³ R ⁴ 、-N ⁺ R ³ R ⁴ R ⁵ X ^- (R ³ ～R ⁵ Each independently represents an alkyl group having 1 to 8 carbon atoms, X ^- Representing a counter anion), a group represented by the following formula PO, and the like.

Among these hydrophilic groups, the group represented by-CONR is preferable ¹ R ² Or a group represented by the formula PO, more preferably a group represented by the formula PO.

[ chemical formula 11]

In the formula PO, L ^P Each independently represents an alkylene group, R ^P Represents a hydrogen atom or an alkyl group, and n represents an integer of 1 to 100.

In the formula PO, L ^P Each independently is preferably vinyl, 1-methylvinyl or 2-methylvinyl, more preferably vinyl.

In the formula PO, R ^P The alkyl group is preferably a hydrogen atom or an alkyl group having 1 to 18 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, still more preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and particularly preferably a hydrogen atom or a methyl group.

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

The content of the structural unit having a hydrophilic group in the specific binder polymer is preferably 1 to 80% by mass, and more preferably 5 to 60% by mass, with respect to the total mass of the specific binder polymer.

Other structural units-

Certain binder polymers may also contain other structural units. The other constituent unit may include, but is not limited to, other constituent units than the above-described constituent units, and examples thereof include those formed from acrylamide compounds, vinyl ether compounds, and the like.

Examples of the acrylamide compound include (meth) acrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-propyl (meth) acrylamide, N-butyl (meth) acrylamide, N '-dimethyl (meth) acrylamide, N' -diethyl (meth) acrylamide, N-hydroxyethyl (meth) acrylamide, N-hydroxypropyl (meth) acrylamide, and N-hydroxybutyl (meth) acrylamide.

Examples of the vinyl ether compound include methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, n-butyl vinyl ether, tert-butyl vinyl ether, 2-ethylhexyl vinyl ether, n-nonyl vinyl ether, lauryl vinyl ether, cyclohexyl methyl vinyl ether, 4-methylcyclohexyl methyl vinyl ether, benzyl vinyl ether, dicyclopentenyl vinyl ether, 2-dicyclopentenyloxyethyl vinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether, butoxyethyl vinyl ether, methoxyethoxyethyl vinyl ether, ethoxyethoxyethoxyethyl vinyl ether, methoxypolyethylene glycol vinyl ether, tetrahydrofurfuryl vinyl ether, 2-hydroxyethyl vinyl ether, 2-hydroxypropyl vinyl ether, 4-hydroxybutyl vinyl ether, 4-hydroxymethylcyclohexyl methyl vinyl ether, diethylene glycol monovinyl ether, polyethylene glycol vinyl ether, chloroethyl vinyl ether, chlorobutyl vinyl ether, chloroethyloxyethyl vinyl ether, phenylethyl vinyl ether, and polyethylene glycol phenoxyvinyl ether.

The content of the other structural unit in the specific binder polymer is preferably 0.5 to 50% by mass, and more preferably 1 to 30% by mass, based on the total mass of the specific binder polymer.

Method for producing specific binder polymers

The method for producing the specific binder polymer is not particularly limited, and can be produced by a known method.

For example, the polymerizable compound is obtained by polymerizing an aromatic vinyl compound, an acrylonitrile compound, and, if necessary, at least one compound selected from the group consisting of the N-vinyl heterocyclic compound, the compound used for forming the structural unit having an ethylenically unsaturated group, the compound used for forming the structural unit having an acidic group, the compound used for forming the structural unit having a hydrophobic group, and the compound used for forming the other structural unit by a known method.

Molecular weight-

The weight average molecular weight of the specific binder polymer is preferably 3,000 to 300,000, more preferably 5,000 to 100,000.

Specific examples-

Specific examples of the specific binder polymer are shown in the following table, but the specific binder polymer used in the present invention is not limited thereto.

[ chemical formula 12]

[ chemical formula 13]

In the specific examples described above, for example, the expression "40/30/10/20" in P1-4 indicates the content ratio (mass ratio) of the 1 st structural unit, the 2 nd structural unit, the 3 rd structural unit and the 4 th structural unit from the left, respectively.

In the specific examples described above, the content ratio of each constituent unit can be appropriately changed in accordance with the preferable range of the content of each constituent unit.

The weight average molecular weight of each compound shown in the specific examples can be appropriately changed depending on the preferable range of the weight average molecular weight of the specific binder polymer.

Content-

The image recording layer may contain one specific binder polymer alone, or two or more types may be used simultaneously.

The content of the specific binder polymer is preferably 5% by mass or more and 95% by mass or less, more preferably 7% by mass or more and 80% by mass or less, and still more preferably 10% by mass or more and 60% by mass or less, with respect to the total mass of the image recording layer.

[ Electron donating type polymerization initiator ]

The image recording layer used in the present invention preferably contains an electron donating polymerization initiator. It is considered that the electron donating type polymerization initiator contributes to the improvement of chemical resistance and brush resistance in the lithographic printing plate. Examples of the electron donating polymerization initiator include the following 5 types.

(i) Alkyl or arylate type complexes: it is believed that the carbon-heterobonds are oxidatively cleaved and active radicals are generated. Specifically, a borate compound and the like can be given.

(ii) Aminoacetic acid compound: it is considered that the C — X bond on the carbon adjacent to nitrogen is cleaved by oxidation to generate an active radical. X is preferably a hydrogen atom, a carboxyl group, a trimethylsilyl group or a benzyl group. Specific examples thereof include N-phenylglycine (which may have a substituent on the phenyl group), N-phenyliminodiacetic acid (which may have a substituent on the phenyl group), and the like.

(iii) A sulfur-containing compound: the compound obtained by substituting the nitrogen atom of the glycine compound with a sulfur atom can generate an active radical by the same action. Specifically, there may be mentioned phenylthioacetic acid (which may have a substituent in the phenyl group), and the like.

(iv) A tin-containing compound: the compound obtained by substituting the nitrogen atom of the glycine compound with a tin atom can generate an active radical by the same action.

(v) Sulfinates: can generate active radicals by oxidation. Specific examples thereof include sodium arylsulfinate and the like.

Of these electron-donating polymerization initiators, the image-recording layer preferably contains a borate compound. The borate compound is preferably a tetraarylborate compound or a monoalkyltriarylborate compound, and from the viewpoint of stability of the compound, a tetraarylborate compound is more preferably used, and a tetraphenylborate compound is particularly preferably used.

The counter cation of the borate compound is not particularly limited, but is preferably an alkali metal ion or a tetraalkylammonium ion, and more preferably a sodium ion, a potassium ion or a tetrabutylammonium ion.

Specific examples of the borate compound include sodium tetraphenylborate.

Hereinafter, preferred specific examples of the electron donating polymerization initiator are shown in B-1 to B-8, but the electron donating polymerization initiator is not limited thereto. In the following chemical formula, bu represents an n-butyl group, and Z represents a counter cation.

As the counter cation represented by Z, na may be mentioned ⁺ 、K ⁺ And N ⁺ (Bu) ₄ And the like. Bu mentioned above represents an n-butyl group.

Further, as the counter cation represented by Z, an onium ion in an electron accepting type polymerization initiator described later can be preferably used.

[ chemical formula 14]

The electron-donating polymerization initiator may be used alone or in combination of two or more.

The content of the electron-donating polymerization initiator is preferably 0.01 to 30% by mass, more preferably 0.05 to 25% by mass, and still more preferably 0.1 to 20% by mass, based on the total mass of the image recording layer.

[ polymerizable Compound ]

The image recording layer in the present invention preferably contains a polymerizable compound.

In the present invention, even if the compound is a polymerizable compound, the compound corresponding to the specific binder polymer, the polymer particles described later, and the binder polymer other than the specific binder polymer described later does not correspond to the polymerizable compound.

The molecular weight (weight average molecular weight in the case of having a molecular weight distribution) of the polymerizable compound is preferably 50 or more and less than 2,500, and more preferably 50 or more and 2,000 or less.

The polymerizable compound used in the present invention may be, for example, a radical polymerizable compound or a cationic polymerizable compound, but is preferably an addition polymerizable compound (ethylenically unsaturated compound) having at least one ethylenically unsaturated bond. The ethylenically unsaturated compound is preferably a compound having at least one terminal ethylenically unsaturated bond, and more preferably a compound having 2 or more terminal ethylenically unsaturated bonds. The polymerizable compound has a chemical form such as a monomer, a prepolymer, that is, a dimer, a trimer, or an oligomer, or a mixture thereof.

Examples of the monomer include unsaturated carboxylic acids (e.g., acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, and maleic acid), esters thereof, and amides thereof, and esters of unsaturated carboxylic acids and polyhydric alcohol compounds, and amides of unsaturated carboxylic acids and polyhydric amine compounds are preferably used. Further, addition reaction products of unsaturated carboxylic acid esters or amides having a nucleophilic substituent such as a hydroxyl group, an amino group, or a mercapto group with monofunctional or polyfunctional isocyanates or epoxies, dehydration condensation reaction products with monofunctional or polyfunctional carboxylic acids, and the like are also preferably used. Also, addition reaction products of unsaturated carboxylic acid esters or amides having electrophilic substituent groups such as isocyanate group and epoxy group with monofunctional or polyfunctional alcohols, amines and thiols are preferable, and substitution reaction products of unsaturated carboxylic acid esters or amides having leaving substituent groups such as halogen atom and tosyloxy group with monofunctional or polyfunctional alcohols, amines and thiols are more preferable. As another example, a compound group in which the unsaturated carboxylic acid is substituted with an unsaturated phosphonic acid, styrene, vinyl ether, or the like can also be used. These are described in Japanese patent application laid-open No. 2006-508380, japanese patent application laid-open No. 2002-287344, japanese patent application laid-open No. 2008-256850, japanese patent application laid-open No. 2001-342222, japanese patent application laid-open No. 9-179296, japanese patent application laid-open No. 9-179297, japanese patent application laid-open No. 9-179298, japanese patent application laid-open No. 2004-294935, japanese patent application laid-open No. 2006-243493, japanese patent application laid-open No. 2002-275129, japanese patent application laid-open No. 2003-064130, japanese patent application laid-open No. 2003-280187, japanese patent application laid-open No. 10-333321, and the like.

Specific examples of the ester monomer of the polyol compound and the unsaturated carboxylic acid include ethylene glycol diacrylate, 1, 3-butanediol diacrylate, tetramethylene glycol diacrylate, propylene glycol diacrylate, trimethylolpropane triacrylate, hexanediol diacrylate, tetraethylene glycol diacrylate, pentaerythritol tetraacrylate, sorbitol triacrylate, ethylene oxide isocyanurate (EO) -modified triacrylate, and polyester acrylate oligomer. Examples of the methacrylate include tetramethylene glycol dimethacrylate, neopentyl glycol dimethacrylate, trimethylolpropane trimethacrylate, ethylene glycol dimethacrylate, pentaerythritol trimethacrylate, bis [ p- (3-methacryloyloxy-2-hydroxypropoxy) phenyl ] dimethyl methane, bis [ p- (methacryloyloxy-ethoxy) phenyl ] dimethyl methane and the like. Specific examples of the amide monomer of the polyamine compound and the unsaturated carboxylic acid include methylenebisacrylamide, methylenebismethacrylamide, 1, 6-hexamethylenebisacrylamide, diethylenetriaminetriacrylate, xylylenebisacrylamide, diphenylenedimethacrylamide, and the like.

Further, a urethane addition polymerizable compound produced by an addition reaction of an isocyanate and a hydroxyl group is also preferable, and specific examples thereof include a vinyl urethane compound containing 2 or more polymerizable vinyl groups in 1 molecule, which is obtained by adding a polyisocyanate compound having 2 or more isocyanate groups in 1 molecule and a hydroxyl group-containing vinyl monomer represented by the following formula (M) as described in japanese patent publication No. 48-041708.

CH ₂ ＝C(R ^M4 )COOCH ₂ CH(R ^M5 )OH (M)

In the formula (M), R ^M4 And R ^M5 Each independently represents a hydrogen atom or a methyl group.

Also preferred are urethane compounds having a hydrophilic group, which are described in Japanese patent laid-open Nos. Sho 51-037193, hei 2-032293, hei 2-016765, hei 2003-344997, hei 2006-065210, japanese Kokoku No. Sho 58-049860, hei 56-017654, hei 62-039417, hei 62-039418, hei 2000-250211, and Hei 2007-094138, and U.S. Pat. No. 7153632, japanese Kokai No. Hei 8-505958, hei 2007-293221, and Hei 2007-293223.

The structure of the polymerizable compound can be arbitrarily set to the details of the method of use such as single use or simultaneous use, and the amount of addition.

The content of the polymerizable compound is preferably 5 to 75% by mass, more preferably 10 to 70% by mass, and still more preferably 15 to 60% by mass, based on the total mass of the image recording layer.

The content of the specific binder polymer is preferably more than 0% by mass and 400% by mass or less, more preferably 25% by mass to 300% by mass, and still more preferably 50% by mass to 200% by mass, based on the total mass of the polymerizable compounds in the image recording layer.

In the image recording layer, the specific binder polymer and the polymerizable compound preferably have a sea-island structure. For example, a structure in which the above-mentioned polymerizable compound is dispersed in islands (discontinuous layer) in the sea (continuous phase) of a specific binder polymer can be employed. It is considered that the sea-island structure is easily formed by setting the content of the specific binder polymer to the value within the above range with respect to the total mass of the polymerizable compound.

[ Electron-accepting polymerization initiator ]

The image recording layer preferably contains an electron acceptor type polymerization initiator.

The electron accepting type polymerization initiator used in the present invention is a compound which generates a polymerization initiating species such as a radical or a cation by the energy of light, heat or both, and can be appropriately selected from known thermal polymerization initiators, compounds having a bond with a small bond dissociation energy, photopolymerization initiators and the like.

The electron acceptor type polymerization initiator is preferably a radical polymerization initiator, and more preferably an onium compound.

The electron-accepting type polymerization initiator is preferably an infrared photosensitive polymerization initiator.

The electron accepting type polymerization initiator may be used singly or in combination of two or more.

Examples of the radical polymerization initiator include (a) an organic halide, (b) a carbonyl compound, (c) an azo compound, (d) an organic peroxide, (e) a metallocene compound, (f) an azide compound, (g) a hexaarylbiimidazole compound, (i) a disulfone compound, (j) an oxime ester compound, and (k) an onium compound.

(a) As the organic halide, for example, compounds described in paragraphs 0022 to 0023 of jp 2008-195018 a are preferable.

(b) As the carbonyl compound, for example, a compound described in paragraph 0024 of japanese patent application laid-open No. 2008-195018 is preferable.

(c) As the azo compound, for example, an azo compound described in Japanese patent application laid-open No. 8-108621 can be used.

(d) As the organic peroxide, for example, a compound described in paragraph 0025 of japanese patent application laid-open No. 2008-195018 is preferable.

(e) As the metallocene compound, for example, a compound described in paragraph 0026 of jp 2008-195018 a is preferable.

(f) Examples of the azide compound include compounds such as 2, 6-bis (4-azidobenzylidene) -4-methylcyclohexanone.

(g) As the hexaarylbiimidazole compound, for example, a compound described in paragraph 0027 of japanese unexamined patent publication No. 2008-195018 is preferable.

(i) Examples of the disulfone compound include those described in Japanese patent application laid-open Nos. 61-166544 and 2002-328465.

(j) The oxime ester compound is preferably a compound described in paragraphs 0028 to 0030 of jp 2008-195018 a, for example.

Among the above-mentioned electron-accepting polymerization initiators, preferred compounds include oxime ester compounds and onium compounds from the viewpoint of curability. Among these, from the viewpoint of brush resistance, an iodonium salt compound, a sulfonium salt compound, or an azinium salt compound is preferable, an iodonium salt compound or a sulfonium salt compound is more preferable, and an iodonium salt compound is further more preferable.

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

As an example of the iodonium salt compound, a diaryliodonium salt compound is preferable, an electron donating group is particularly preferable, for example, a diphenyliodonium salt compound substituted with an alkyl group or an alkoxy group is more preferable, and an asymmetric diphenyliodonium salt compound is preferable. Specific examples thereof include diphenyliodonium = hexafluorophosphate, 4-methoxyphenyl-4- (2-methylpropyl) phenyliodonium = hexafluorophosphate, 4- (2-methylpropyl) phenyl-p-tolyliodonium = hexafluorophosphate, 4-hexyloxyphenyl-2, 4, 6-trimethoxyphenyliodonium = hexafluorophosphate, 4-hexyloxyphenyl-2, 4-diethoxyphenyliodonium = tetrafluoroborate, 4-octyloxyphenyl-2, 4, 6-trimethoxyphenyliodonium = 1-perfluorobutylsulfonate, 4-octyloxyphenyl-2, 4, 6-trimethoxyphenyliodonium = hexafluorophosphate, and bis (4-tert-butylphenyl) iodonium = tetraphenylborate.

As an example of the sulfonium salt compound, a triarylsulfonium salt compound is preferable, and particularly, an electron-withdrawing group is preferable, and for example, a triarylsulfonium salt compound in which at least a part of groups on an aromatic ring is substituted with a halogen atom is preferable, and a triarylsulfonium salt compound in which the total number of substitution of halogen atoms on an aromatic ring is 4 or more is more preferable. Specific examples thereof include triphenylsulfonium = hexafluorophosphate, triphenylsulfonium = benzoylformate, bis (4-chlorophenyl) phenylsulfonium = benzoylformate, bis (4-chlorophenyl) -4-tolylsulfonium = tetrafluoroborate, tris (4-chlorophenyl) sulfonium =3, 5-bis (methoxycarbonyl) benzenesulfonate, tris (4-chlorophenyl) sulfonium = hexafluorophosphate, and tris (2, 4-dichlorophenyl) sulfonium = hexafluorophosphate.

The counter anion of the iodonium salt compound and the sulfonium salt compound is preferably a sulfonamide or sulfonimide, and more preferably sulfonimide.

As the sulfonamide, aryl sulfonamide is preferable.

Also, as the sulfonimide, bis-aryl sulfonimide is preferable.

Specific examples of the sulfonamide or the sulfonimide are shown below, but the present invention is not limited to these. In the following specific examples, ph represents a phenyl group, me represents a methyl group, and Et represents an ethyl group.

[ chemical formula 15]

In a preferred embodiment of the present invention, a salt is formed from the electron accepting polymerization initiator and the electron donating polymerization initiator.

Specifically, for example, there is a mode in which the onium compound is a salt of an onium ion and an anion (for example, tetraphenylborate anion) in the electron donating polymerization initiator. More preferably, an iodonium borate compound in which a salt is formed from an iodonium cation (for example, a di-tri-iodonium cation) in the iodonium salt compound described later and a borate anion in the electron-donating polymerization initiator is used.

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

The content of the electron accepting type polymerization initiator is preferably 0.1 to 50% by mass, more preferably 0.5 to 30% by mass, and particularly preferably 0.8 to 20% by mass, with respect to the total mass of the image recording layer.

[ Infrared absorber ]

The image recording layer preferably contains an infrared absorber

Examples of the infrared absorber include pigments and dyes.

As The dye used as The infrared absorber, there can be used a commercially available dye and a known dye described in The literature such as "dye review" (The Society of Synthetic Organic Chemistry, japan. Ed., showa 45 (1970) "). Specific examples thereof include azo dyes, metal complex azo dyes, pyrazolone azo dyes, naphthoquinone dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinonimine dyes, methine dyes, cyanine dyes, squarylium pigments, pyrylium salts, and metal thiolate complexes.

Among these dyes, particularly preferable dyes include cyanine dyes, squarylium dyes, pyrylium salts, nickel thiol complexes, and indocyanine dyes. Further, cyanine dyes and indocyanine dyes can be mentioned. Among them, cyanine is particularly preferable.

Specific examples of the cyanine dye include compounds described in paragraphs 0017 to 0019 of Japanese patent application laid-open No. 2001-133969, paragraphs 0016 to 0021 of Japanese patent application laid-open No. 2002-023360, and paragraphs 0012 to 0037 of Japanese patent application laid-open No. 2002-040638, preferably in paragraphs 0034 to 0041 of Japanese patent application laid-open No. 2002-278057, and paragraphs 0080 to 0086 of Japanese patent application laid-open No. 2008-195018, and particularly preferably in paragraphs 0035 to 0043 of Japanese patent application laid-open No. 2007-090850, and paragraphs 0105 to 0113 of Japanese patent application laid-open No. 2012-206495.

Further, it is also possible to preferably use the compounds described in paragraphs 0008 to 0009 of Japanese patent application laid-open No. 5-005005 and paragraphs 0022 to 0025 of Japanese patent application laid-open No. 2001-222101.

The pigment is preferably a compound described in paragraphs 0072 to 0076 of Japanese patent application laid-open No. 2008-195018.

The infrared absorber is preferably an infrared absorber that decomposes by exposure to infrared light (hereinafter, also referred to as a "decomposable infrared absorber").

It is estimated that a film having high polarity can be obtained by using an infrared absorber which decomposes by infrared exposure as the infrared absorber and accelerating polymerization of the infrared absorber or its decomposition product, and by using a specific binder polymer, and that the brush resistance and the brush resistance even when a UV ink is used (UV brush resistance) are excellent by allowing the decomposition product of the infrared absorber to interact with the binder polymer.

The decomposable infrared absorber is preferably an infrared absorber having a function of developing a color by absorbing and decomposing infrared rays upon exposure to infrared rays. The term "color development" refers to a case where there is almost no absorption in the visible light region (wavelength region of 400nm or more and less than 750 nm) before infrared exposure, but absorption occurs in the visible light region by infrared exposure, and also includes a case where absorption in a lower wavelength region than the visible light region is made longer in the visible light region.

Hereinafter, a color-developing compound formed by the decomposable infrared absorbing agent absorbing infrared light upon exposure to infrared light and decomposing the infrared light is also referred to as a "color-developing body of the decomposable infrared absorbing agent".

The decomposable infrared absorbing agent preferably has a function of absorbing infrared rays by infrared ray exposure and converting the absorbed infrared rays into heat.

The decomposable infrared absorbing agent may be any decomposable infrared absorbing agent that absorbs and decomposes at least a part of light in the infrared wavelength region (wavelength 750nm to 1 mm), and is preferably an infrared absorbing agent that has a maximum absorption in the wavelength region of 750nm to 1,400nm.

The decomposable infrared absorbing agent is preferably an infrared absorbing agent decomposed by heat, electron movement, or both of them due to infrared exposure, and more preferably an infrared absorbing agent decomposed by electron movement due to infrared exposure. Here, "decomposition by electron transfer" means that, by exposure to infrared light, electrons excited from the HOMO (highest occupied molecular orbital) to the LUMO (lowest unoccupied molecular orbital) of the decomposable infrared absorber undergo intramolecular electron transfer to an electron-accepting group (group close to the LUMO potential) in a molecule, thereby causing decomposition.

The above-mentioned decomposable infrared absorber is preferably a cyanine dye decomposed by infrared exposure from the viewpoints of color developability and UV resistance of the obtained lithographic printing plate.

The infrared absorber is more preferably a compound represented by the following formula 1 from the viewpoints of color developability and UV resistance of the obtained lithographic printing plate.

[ chemical formula 16]

In the formula 1, R ¹ Represents R by infrared ray exposure ¹ -L bond-breaking group, R ₁₁ ～R ₁₈ Independently represent a hydrogen atom, a halogen atom, -Ra, -ORb, -SRc or-NRdRe, ra to Re independently represent a hydrocarbon group, A ₁ 、A ₂ And a plurality of R ₁₁ ～R ₁₈ May be linked to form a monocyclic or polycyclic ring, A ₁ And A ₂ Each independently represents an oxygen atom, a sulfur atom or a nitrogen atom, n ₁₁ And n ₁₂ Each independently represents an integer of 0 to 5, wherein n ₁₁ And n ₁₂ Is 2 or more, n ₁₃ And n ₁₄ Each independently represents 0 or 1, L represents an oxygen atom, a sulfur atom or-NR ¹⁰ -，R ¹⁰ Represents a hydrogen atom, an alkyl group or an aryl group, and Za represents a counter ion for neutralizing a charge.

When the cyanine dye represented by formula 1 is exposed to infrared light, R is represented by ¹ -L bond cleavage, L being = O, = S or = NR ¹⁰ Thereby forming a color developing body of the decomposable infrared ray absorbing agent. R is ¹ Disassociates to form radicals or ions. These contribute to polymerization of the compound having polymerizability contained in the image recording layer.

In formula 1, R ₁₁ ～R ₁₈ Each independently preferably a hydrogen atom, -Ra, -ORb, -SRc or-NRdRe.

The hydrocarbon group in Ra to Re is preferably a hydrocarbon group having 1 to 30 carbon atoms, more preferably a hydrocarbon group having 1 to 15 carbon atoms, and still more preferably a hydrocarbon group having 1 to 10 carbon atoms. The hydrocarbon group may be linear, branched, or cyclic.

R in formula 1 ₁₁ ～R ₁₄ Each independently is preferably a hydrogen atom or a hydrocarbon group, more preferably a hydrogen atom or an alkyl group, and still more preferably a hydrogen atom.

And R bonded to a carbon atom bonded to L ₁₁ And R ₁₃ Preferably an alkyl group, more preferably the two are linked to form a ring. The ring formed as described above is preferably a 5-membered ring or a 6-membered ring, and more preferably a 5-membered ring.

And A ₁ ⁺ R bound to the carbon atom to which it is bound ₁₂ And A ₂ R bound to the carbon atom to which it is bound ₁₄ Preferably each of R ₁₅ And R ₁₇ Joined to form a ring.

R in formula 1 ₁₅ Preferably a hydrocarbon group. And, preferably R ₁₅ And A ₁ ⁺ R bound to the carbon atom to which it is bound ₁₂ Joined to form a ring. The ring to be formed is preferably an indole ring, a pyrylium ring, a Thiopyrylium (Thiopyrylium) ring, a benzoxazoline ring or a benzimidazoline ring, and is preferably a ring represented byFrom the viewpoint of color properties, indole rings are more preferable.

R in formula 1 ₁₇ Preferably a hydrocarbon group. And, preferably R ₁₇ And A ₂ R bound to the carbon atom to which it is bound ₁₄ Joined to form a ring. The ring to be formed is preferably an indole ring, a pyran ring, a thiopyran ring, a benzoxazole ring or a benzimidazole ring, and more preferably an indole ring from the viewpoint of color developability.

R in formula 1 ₁₅ And R ₁₇ The same groups are preferred, and in the case of forming separate rings, the same rings are preferably formed.

R in formula 1 ₁₆ And R ₁₈ Preferably the same groups.

Furthermore, from the viewpoint of improving the water solubility of the compound represented by formula 1, R ₁₆ And R ₁₈ Each independently is preferably an alkyl group having a (poly) oxyalkylene group or an alkyl group having an anionic structure, more preferably an alkoxyalkyl group, an alkyl group having a carboxylate group or a sulfonate group, and still more preferably an alkyl group having a sulfonate group at a terminal. The alkyl group is preferably an alkyl group having 1 to 10 carbon atoms, and more preferably an alkyl group having 1 to 4 carbon atoms.

The counter cation of the above anionic structure may be R in the formula 1 ¹ A cation which can be contained in-L or A ₁ ⁺ The cation may be an alkali metal cation or an alkaline earth metal cation.

The counter cation of the sulfonate group may be R in formula 1 ¹ A cation which can be contained in-L or A ₁ ⁺ The cation may be an alkali metal cation or an alkaline earth metal cation.

Further, the maximum absorption wavelength of the compound represented by formula 1 is made longer, and R is from the viewpoint of color developability and brush resistance in a lithographic printing plate ₁₆ And R ₁₈ Each independently is preferably an alkyl group or an alkyl group having an aromatic ring. The alkyl group is preferably an alkyl group having 1 to 10 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms, and still more preferably a methyl group or an ethyl group. The alkyl group having an aromatic ring is preferably a terminal groupThe alkyl group having an aromatic ring is more preferably a 2-phenylethyl group, a 2-naphthylethyl group or a 2- (9-anthryl) ethyl group.

N in formula 1 ₁₁ And n ₁₂ The same integer of 0 to 5 is preferable, an integer of 1 to 3 is more preferable, 1 or 2 is further preferable, and 2 is particularly preferable.

A in formula 1 ₁ And A ₂ Each independently represents an oxygen atom, a sulfur atom or a nitrogen atom, preferably a nitrogen atom.

A in formula 1 ₁ And A ₂ Preferably the same atom.

Za in formula 1 represents a counter ion that neutralizes charge. When the anion species is represented, there are sulfonate ions, carboxylate ions, tetrafluoroborate ions, hexafluorophosphate ions, hexafluoroantimonate ions, p-toluenesulfonate ions, perchlorate ions and the like, and hexafluoroantimonate ions or hexafluorophosphate ions are preferable. When a cation species is represented, examples thereof include an alkali metal ion, an alkaline earth metal ion, an ammonium ion, a pyridinium ion, a sulfonium ion, and the like, preferably a sodium ion, a potassium ion, an ammonium ion, a pyridinium ion, or a sulfonium ion, and more preferably a sodium ion, a potassium ion, or an ammonium ion.

R ₁₁ ～R ₁₈ And R ¹ L can have an anionic structure and a cationic structure, if R ₁₁ ～R ₁₈ And R ¹ L all being charge-neutral radicals, then Za is a monovalent counter anion, e.g. at R ₁₁ ～R ₁₈ And R ¹ When L has an anionic structure of 2 or more, za can be a counter cation.

When the cyanine dye represented by formula 1 has a charge-neutral structure in the entire compound, za does not exist.

To the formula 1 through R ¹ Infrared ray exposure represented by R ¹ The group in which the-L bond is cleaved will be described in detail later.

The decomposable infrared absorber is more preferably a cyanine dye represented by the following formula 1-a from the viewpoints of color developability and UV resistance of the obtained lithographic printing plate.

[ chemical formula 17]

In the formula 1-A, R ¹ Denotes exposure to infrared light and R ¹ -L bond breaking group, R ² And R ³ Each independently represents a hydrogen atom or an alkyl group, R ² And R ³ May be linked to each other to form a ring, ar ¹ And Ar ² Each independently represents a group forming a benzene ring or a naphthalene ring, Y ¹ And Y ² Each independently represents an oxygen atom, a sulfur atom, -NR ⁰ Or a dialkylmethylene group, R ⁰ Represents a hydrogen atom, an alkyl group or an aryl group, R ⁴ And R ⁵ Each independently represents an alkyl group, -CO ₂ M radical or-PO ₃ M ₂ M represents a hydrogen atom, a Na atom, a K atom or an onium group, R ⁶ ～R ⁹ Each independently represents a hydrogen atom or an alkyl group, L represents an oxygen atom, a sulfur atom or-NR ¹⁰ -，R ¹⁰ Represents a hydrogen atom, an alkyl group or an aryl group, and Za represents a counter ion for neutralizing a charge.

In the formula 1-A, R ² ～R ⁹ And R ⁰ The alkyl group in (1) is preferably an alkyl group having 1 to 30 carbon atoms, more preferably an alkyl group having 1 to 15 carbon atoms, and still more preferably an alkyl group having 1 to 10 carbon atoms. The alkyl group may be linear, branched, or cyclic.

Specific examples thereof include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, hexadecyl, octadecyl, eicosyl, isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, neopentyl, 1-methylbutyl, isohexyl, 2-ethylhexyl, 2-methylhexyl, cyclohexyl, cyclopentyl and 2-norbornyl groups.

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

The above alkyl group may have a substituent. Examples of the substituent include an alkoxy group, an aryloxy group, an amino group, an alkylthio group, an arylthio group, a halogen atom, a carboxyl group, a carboxylate group, a sulfo group, a sulfonate group, an alkoxycarbonyl group, an aryloxycarbonyl group, and a group obtained by combining these groups.

R ⁰ The aryl group in (4) is preferably an aryl group having 6 to 30 carbon atoms, more preferably an aryl group having 6 to 20 carbon atoms, and still more preferably an aryl group having 6 to 12 carbon atoms.

The above aryl group may have a substituent. Examples of the substituent include an alkyl group, an alkoxy group, an aryloxy group, an amino group, an alkylthio group, an arylthio group, a halogen atom, a carboxyl group, a carboxylate group, a sulfo group, a sulfonate group, an alkoxycarbonyl group, an aryloxycarbonyl group, and a group obtained by combining these groups.

Specific examples thereof include phenyl, naphthyl, p-tolyl, p-chlorophenyl, p-fluorophenyl, p-methoxyphenyl, p-dimethylaminophenyl, p-methylthiophenyl and p-phenylthiophenyl.

Among the aryl groups, a phenyl group, a p-methoxyphenyl group, a p-dimethylaminophenyl group or a naphthyl group is preferred.

R ² And R ³ Preferably joined to form a ring.

At R ² And R ³ When they are linked to form a ring, they are preferably 5-or 6-membered rings, and particularly preferably 5-membered rings.

Y ¹ And Y ² Each independently represents an oxygen atom, a sulfur atom, -NR ⁰ -or dialkylmethylene, preferably-NR ⁰ -or a dialkylmethylene group, more preferably a dialkylmethylene group.

R ⁰ Represents a hydrogen atom, an alkyl group or an aryl group, preferably an alkyl group.

R ⁴ Or R ⁵ The alkyl groups represented may be substituted alkyl groups. As R ⁴ Or R ⁵ Examples of the substituted alkyl group include groups represented by any one of the following formulae (a 1) to (a 4).

[ chemical formula 18]

-R ^W2 -CO ₂ M (a2)

-R ^W3 -PO ₃ M ₂ (a3)

-R ^W4 -SO ₃ M (a4)

In the formulae (a 1) to (a 4), R ^W0 Represents an alkylene group having 2 to 6 carbon atoms, W represents a single bond or an oxygen atom, n _W1 Represents an integer of 1 to 45, R ^W1 Represents an alkyl group having 1 to 12 carbon atoms or-C (= 0) -R ^W5 ，R ^W5 Represents an alkyl group having 1 to 12 carbon atoms, R ^W2 ～R ^W4 Each independently represents a single bond or an alkylene group having 1 to 12 carbon atoms, and M represents a hydrogen atom, a Na atom, a K atom or an onium group.

In the formula (a 1), as R ^W0 Specific examples of the alkylene group include a vinyl group, a n-propylene group, an isopropylene group, a n-butylene group, an isobutylene group, a n-pentylene group, an isopentylene group, a n-hexylene group, and an isohexylene group, and preferably a vinyl group, a n-propylene group, an isopropylene group, and a n-butylene group, and particularly preferably a n-propylene group.

n _W1 Preferably 1 to 10, more preferably 1 to 5, and particularly preferably 1 to 3.

As R ^W1 Specific examples of the alkyl group include a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a tert-butyl group, a n-pentyl group, an isopentyl group, a neopentyl group, a n-hexyl group, a n-octyl group, and a n-dodecyl group, and the like, and preferably a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, and a tert-butyl group, more preferably a methyl group and an ethyl group, and particularly preferably a methyl group.

R ^W5 Alkyl group represented by the formula and R ^W1 The alkyl radicals are preferably identical to R ^W1 The preferred modes of the alkyl groups represented are the same.

Specific examples of the group represented by the formula (a 1) are shown below, but the present invention is not limited to these. In the following structural formulae, me represents a methyl group, et represents an ethyl group, and x represents a bonding site.

[ chemical formula 19]

In the formulae (a 2) to (a 4), R is ^W2 ～R ^W4 Specific examples of the alkylene group include a methylene group, a vinyl group, a n-propylene group, an isopropylene group, a n-butylene group, an isobutylene group, a n-pentylene group, an isopentylene group, a n-hexylene group, an isohexylene group, a n-octylene group, and a n-dodecylene group, and the like, and preferably include a vinyl group, a n-propylene group, an isopropylene group, and a n-butylene group, and particularly preferably include a vinyl group and a n-propylene group.

In the formula (a 3), M which is present in 2 may be the same or different.

In the formulae (a 2) to (a 4), examples of the onium group represented by M include an ammonium group, an iodonium group, a phosphonium group, and a sulfonium group.

Among the groups represented by the formulae (a 1) to (a 4), the group represented by the formula (a 1) or the formula (a 4) is preferable.

In the formula 1-A, R ⁴ And R ⁵ Each is preferably an unsubstituted alkyl group. R ⁴ And R ⁵ Preferably the same group.

R ⁶ ～R ⁹ Each independently represents a hydrogen atom or an alkyl group, preferably a hydrogen atom.

Ar ¹ And Ar ² Each independently represents a group forming a benzene ring or a naphthalene ring. The benzene ring and the naphthalene ring may have a substituent. Examples of the substituent include an alkyl group, an alkoxy group, an aryloxy group, an amino group, an alkylthio group, an arylthio group, a halogen atom, a carboxyl group, a carboxylate group, a sulfo group, a sulfonate group, an alkoxycarbonyl group, an aryloxycarbonyl group, an acyloxy group, a phosphonate group, and a group obtained by combining these groups. The substituent is preferably an alkyl group.

Further, ar is used for increasing the maximum absorption wavelength of the compound represented by the formula 1-A to a longer wavelength, and from the viewpoint of improving color developability and the printing durability of a lithographic printing plate ¹ And Ar ² Each independently is preferably a group forming a naphthalene ring or a benzene ring having an alkyl group or an alkoxy group as a substituent, more preferably a naphthalene ringThe group of a ring or a benzene ring having an alkoxy group as a substituent is particularly preferably a group forming a naphthalene ring or a benzene ring having a methoxy group as a substituent.

In formula 1-A, ar ¹ Or Ar ² Preferred is a group forming a group represented by the following formula (b 1).

[ chemical formula 20]

In the formula (b 1), R ¹⁹ Represents an alkyl group having 1 to 12 carbon atoms. n3 represents an integer of 1 to 4. * Indicating the bonding site.

Za represents a counter ion for neutralizing charge. The compound represented by the formula 1-a has an ionic substituent corresponding to the structure thereof, and when neutralization of charge is not required, za is not required. When Za represents an anionic species, examples thereof include a sulfonate ion, a carboxylate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, a p-toluenesulfonate ion, a perchlorate ion, and a hexafluoroantimonate ion, and a hexafluorophosphate ion or a hexafluoroantimonate ion is preferable. When Za represents a cationic species, examples thereof include an alkali metal ion, an alkaline earth metal ion, an ammonium ion, a pyridinium ion, a sulfonium ion, and the like, preferably a sodium ion, a potassium ion, an ammonium ion, a pyridinium ion, or a sulfonium ion, and more preferably a sodium ion, a potassium ion, or an ammonium ion.

R ¹ ～R ⁹ 、R ⁰ 、Ar ¹ 、Ar ² 、Y ¹ And Y ² Can have an anionic structure and a cationic structure, if R ¹ ～R ⁹ 、R ⁰ 、Ar ¹ 、Ar ² 、Y ¹ And Y ² All being charge-neutral radicals, then Za is a monovalent counter anion, e.g. at R ¹ ～R ⁹ 、R ⁰ 、Ar ¹ 、Ar ² 、Y ¹ And Y ² When the anion structure has 2 or more anions, za can be a counter cation.

As in the above formula 1And in formula 1-A by R ¹ R is an infrared ray exposure ¹ The group in which the bond of-L is broken will be described later.

In the case where L is an oxygen atom in formula 1 or formula 1-A, R is an oxygen atom in view of color developability ¹ The group represented by any one of the following formulae (1-1) to (1-7) is preferable, and the group represented by any one of the following formulae (1-1) to (1-3) is more preferable.

[ chemical formula 21]

In the formulae (1-1) to (1-7), \9679denotesa bonding site with an oxygen atom represented by L in the formula 1 or the formula 1-A, R ²⁰ Each independently represents a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, -OR ²⁴ 、-NR ²⁵ R ²⁶ or-SR ²⁷ ，R ²¹ Each independently represents a hydrogen atom, an alkyl group or an aryl group, R ²² Represents aryl, -OR ²⁴ 、-NR ²⁵ R ²⁶ 、-SR ²⁷ 、-C(＝O)R ²⁸ 、-OC(＝O)R ²⁸ Or a halogen atom, R ²³ Represents an aryl, alkenyl, alkoxy or onium group, R ²⁴ ～R ²⁷ Each independently represents a hydrogen atom, an alkyl group or an aryl group, R ²⁸ Represents alkyl, aryl, -OR ²⁴ 、-NR ²⁵ R ²⁶ or-SR ²⁷ ，Z ¹ Represents a counter ion for neutralizing a charge.

At R ²⁰ 、R ²¹ And R ²⁴ ～R ²⁸ Preferred modes for the case of alkyl radicals with R ² ～R ⁹ And R ⁰ The preferable mode of the alkyl group in (1) is the same.

R ²⁰ And R ²³ The number of carbon atoms of the alkenyl group in (b) is preferably 1 to 30, more preferably 1 to 15, and still more preferably 1 to 10.

At R ²⁰ ～R ²⁸ Preferred modes for the aryl radical with R ⁰ The preferred mode of aryl in (1) is the same.

From the viewpoint of color renderingR in the formula (1-1) ²⁰ Preferably alkyl, alkenyl, aryl, -OR ²⁴ 、-NR ²⁵ R ²⁶ or-SR ²⁷ More preferably alkyl, -OR ²⁴ 、-NR ²⁵ R ²⁶ or-SR ²⁷ Further preferably an alkyl group OR-OR ²⁴ Particularly preferably-OR ²⁴ 。

And, R in the formula (1-1) ²⁰ In the case of an alkyl group, the above alkyl group may be an alkyl group having an arylthio group, an alkoxycarbonyl group or an arylsulfonyl group in the α -position, and is preferably an alkyl group having an arylthio group or an alkoxycarbonyl group in the α -position.

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

R in the formula (1-1) ²⁰ In the case of an alkenyl group, the alkenyl group may be an alkenyl group having an aryl group or a hydroxyaryl group.

R in the formula (1-2) from the viewpoint of color rendering properties ²¹ Preferably a hydrogen atom.

R in the formula (1-2) is a group represented by the formula ²² preferably-C (= O) OR ²⁴ 、-OC(＝O)OR ²⁴ OR a halogen atom, more preferably-C (= O) OR ²⁴ OR-OC (= O) OR ²⁴ . R in the formula (1-2) ²² is-C (= O) OR ²⁴ OR-OC (= O) OR ²⁴ In the case of (1), R ²⁴ Preferably an alkyl group.

R in the formula (1-3) from the viewpoint of color rendering properties ²¹ Each independently preferably a hydrogen atom or an alkyl group, and at least one R in the formula (1-3) ²¹ More preferably an alkyl group.

And, R ²¹ The alkyl group in (1) is preferably an alkyl group having 1 to 10 carbon atoms, more preferably an alkyl group having 3 to 10 carbon atoms.

And, R ²¹ The alkyl group in (1) is preferably an alkyl group having a branched or cyclic structure, and more preferably an isopropyl group, a cyclopentyl group, a cyclohexyl group or a tert-butyl group. And, R ²¹ The alkyl group in (1) is preferably a secondary or tertiary alkyl group。

R in the formula (1-3) is a group represented by the formula ²³ It is preferably an aryl group, an alkoxy group or an onium group, more preferably a p-dimethylaminophenyl group or a pyridinium group, and still more preferably a pyridinium group.

As R ²³ Examples of the onium group in (1) include a pyridinium group, an ammonium group and a sulfonium group. The onium group may have a substituent. Examples of the substituent include an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an amino group, an alkylthio group, an arylthio group, a halogen atom, a carboxyl group, a sulfo group, an alkoxycarbonyl group, an aryloxycarbonyl group, a group obtained by combining these groups, and the like.

Among them, a pyridinium group is preferable, and an N-alkyl-3-pyridinium group, an N-benzyl-3-pyridinium group, an N- (alkoxypolyalkyleneoxyalkyl) -3-pyridinium group, an N-alkoxycarbonylmethyl-3-pyridinium group, an N-alkyl-4-pyridinium group, an N-benzyl-4-pyridinium group, an N- (alkoxypolyalkyleneoxyalkyl) -4-pyridinium group, an N-alkoxycarbonylmethyl-4-pyridinium group or an N-alkyl-3, 5-dimethyl-4-pyridinium group is more preferable, an N-alkyl-3-pyridinium group or an N-alkyl-4-pyridinium group is further preferable, an N-methyl-3-pyridinium group, an N-octyl-3-pyridinium group, an N-methyl-4-pyridinium group or an N-octyl-4-pyridinium group is particularly preferable, and an N-octyl-3-pyridinium group or an N-octyl-4-pyridinium group is most preferable.

And, in R ²³ In the case of pyridinium group, examples of the counter anion include a sulfonate ion, a carboxylate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, a p-toluenesulfonate ion, a perchlorate ion, and a hexafluoroantimonate ion, and preferably a p-toluenesulfonate ion, a hexafluoroantimonate ion, or a hexafluorophosphate ion.

R in the formula (1-4) from the viewpoint of color rendering properties ²⁰ Preferably an alkyl or aryl group, more preferably 2R ²⁰ One of which is an alkyl group and the other is an aryl group. The above 2R ²⁰ May be joined to form a ring.

R in the formula (1-5) from the viewpoint of color rendering properties ²⁰ Preferably an alkyl groupOr an aryl group, more preferably an aryl group, and further preferably a p-tolyl group.

R in the formula (1-6) from the viewpoint of color rendering properties ²⁰ Each independently is preferably an alkyl or aryl group, more preferably a methyl or phenyl group.

Z in the formula (1-7) from the viewpoint of color rendering properties ¹ As long as it is a counter ion for neutralizing a charge, it may be contained in the Za as a whole.

Z ¹ Preferably a sulfonate ion, a carboxylate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, a hexafluoroantimonate ion, a p-toluenesulfonate ion or a perchlorate ion, more preferably a p-toluenesulfonate ion, a hexafluoroantimonate ion or a hexafluorophosphate ion.

In the case where L is an oxygen atom in formula 1 or formula 1-A, R is more preferably R from the viewpoint of color developability ¹ Is a group represented by the following formula (5).

[ chemical formula 22]

In the formula (5), R ¹⁵ And R ¹⁶ Each independently represents a hydrogen atom, an alkyl group or an aryl group, E represents an onium group, and represents a bonding site to an oxygen atom represented by L in formula 1 or formula 1-A.

R ¹⁵ Or R ¹⁶ Alkyl group represented by the formula and R ² ～R ⁹ And R ⁰ The alkyl in (1) is the same as R in a preferred manner ² ～R ⁹ And R ⁰ The preferable mode of the alkyl group in (1) is the same.

R ¹⁵ Or R ¹⁶ Aryl and R ⁰ The aryl in (A) is the same as R in a preferred embodiment ⁰ The preferred mode of aryl in (1) is the same.

Onium group represented by E and R ²³ In the same manner as the onium group in (1), preferably in the same manner as R ²³ The preferred mode of the onium group in (1) is the same.

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

[ chemical formula 23]

In the formula (6), R ¹⁷ Represents a halogen atom, an alkyl group, an aryl group, a hydroxyl group or an alkoxy group, in the presence of a plurality of R ¹⁷ In the case of (2), a plurality of R ¹⁷ May be the same or different, or a plurality of R ¹⁷ May be joined to form a ring. n2 represents an integer of 0 to 4. R ¹⁸ Represents an alkyl group or an aryl group. Z is a linear or branched member _b Represents a counter ion for neutralizing a charge.

R ¹⁷ Or R ¹⁸ Alkyl or aryl of formula (I) with R ² ～R ⁹ And R ⁰ Alkyl or R in (1) ⁰ The aryl in (A) is the same as R in a preferred embodiment ² ～R ⁹ And R ⁰ Alkyl in (1) or R ⁰ The preferred mode of aryl in (1) is the same.

R ¹⁷ The alkoxy group is preferably an alkoxy group having 1 to 10 carbon atoms, and examples thereof include a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, an isobutoxy group, a tert-butoxy group, and the like.

n2 is preferably 0.

Z _b The counter ion for neutralizing charge represented by the formula (1-7) and Z ¹ In the same manner, the preferable mode is also the same as Z in the formula (1-7) ¹ The preferred manner of this is the same.

Hereinafter, in the case where L is an oxygen atom in the formula 1 or the formula 1-A, R is exemplified ¹ Specific examples of the groups are shown, but the present invention is not limited to these. In the following structural formula, tsO ^- Represents a p-toluenesulfonate anion, \9679andrepresents a bonding site to an oxygen atom represented by L in the formula 1 or the formula 1-A.

[ chemical formula 24]

[ chemical formula 25]

[ chemical formula 26]

[ chemical formula 27]

[ chemical formula 28]

[ chemical formula 29]

[ chemical formula 30]

[ chemical formula 31]

[ chemical formula 32]

In the case where L is an oxygen atom, if R ¹ Aryl or linear alkyl, without causing exposure to infrared-based lightR of (A) to (B) ¹ -cleavage of the O bond.

In the case where L in formula 1 or formula 1-A is a sulfur atom, R ¹ A group represented by the following formula (2-1) is preferred.

[ chemical formula 33]

In the formula (2-1), 9679denotes a bonding site with a sulfur atom represented by L in the formula 1 or the formula 1-A, R ²¹ Each independently represents a hydrogen atom, an alkyl group or an aryl group, R ²² Represents an aryl, alkenyl, alkoxy or onium group.

L is-NR in formula 1 or formula 1-A ¹⁰ In the case of-R bonded to N ¹ A group represented by the following formula (3-1) is preferred.

[ chemical formula 34]

Wherein (3-1) represents a bonding site to a nitrogen atom contained in L in formula 1 or formula 1-A, and X represents ¹ And X ² Each independently represents an oxygen atom or a sulfur atom, and Y represents a group represented by the above formula (2-1).

In the above formula (2-1), with respect to R ²¹ And R ²² As the alkyl, aryl, alkenyl, alkoxy and onium groups, the alkyl, aryl, alkenyl, alkoxy and onium groups described in the above formulae (1-1) to (1-7) can be applied.

In the formula 1 or the formula 1-A, L preferably represents a sulfur atom or-NR from the viewpoint of improving the brush resistance or the like ¹⁰ -and R ¹⁰ Represents a hydrogen atom, an alkyl group or an aryl group.

R in the above formula 1 and formula 1-A ₁ The group represented by the following formula 2 is preferred.

The group represented by formula 2 is preferably R in formula 2 by exposure to infrared light ^Z -a group in which the O bond is broken.

[ chemical formula 35]

In the formula 2, R ^Z Represents an alkyl group, and the wavy line moiety represents a bonding site to a group represented by L in formula 1 or formula 1-A.

As R ^Z Alkyl group represented by the formula, with the above R ² ～R ⁹ And R ⁰ The preferable mode of the alkyl group in (1) is the same.

From the viewpoint of color developability and UV resistance of the lithographic printing plate obtained, the alkyl group is preferably a secondary alkyl group or a tertiary alkyl group, and more preferably a tertiary alkyl group.

In view of color developability and UV resistance of the lithographic printing plate obtained, the alkyl group is preferably an alkyl group having 1 to 8 carbon atoms, more preferably a branched alkyl group having 3 to 10 carbon atoms, still more preferably a branched alkyl group having 3 to 6 carbon atoms, and particularly preferably an isopropyl group or a tert-butyl group, and most preferably a tert-butyl group.

Specific examples of the group represented by the above formula 2 are given below, but the present invention is not limited to these. In the following structural formula, \9679representsa bonding site with L in formula 1 or formula 1-A.

[ chemical formula 36]

Specific examples of the infrared absorber decomposed by infrared exposure are given below, but the present invention is not limited to these.

[ chemical formula 37]

[ chemical formula 38]

[ chemical formula 39]

Further, as the infrared absorber decomposed by infrared exposure, the infrared absorbers described in Japanese patent publication No. 2008-544322 and International publication No. 2016/027886 can be preferably used.

The infrared absorber may be used alone or in combination of two or more. Further, as the infrared absorber, a pigment and a dye may be used together.

The content of the infrared absorber in the image recording layer is preferably 0.1 to 10.0% by mass, and more preferably 0.5 to 5.0% by mass, based on the total mass of the image recording layer.

[ Polymer particles ]

The image recording layer preferably contains polymer particles.

The polymer particles are preferably selected from the group consisting of thermoplastic polymer particles, thermally reactive polymer particles, polymer particles having a polymerizable group, microcapsules containing a hydrophobic compound therein, and microgels (crosslinked polymer particles). Among them, polymer particles or microgels having a polymerizable group are preferable. In a particularly preferred embodiment, the polymer particles comprise at least one ethylenically unsaturated polymerizable group. The presence of such polymer particles can provide an effect of improving the brush resistance of exposed portions and the on-press developability of unexposed portions.

Also, the polymer particles are preferably thermoplastic polymer particles.

As the thermoplastic polymer particles, thermoplastic polymer particles described in, for example, the specifications of Research Disclosure No.33303, japanese patent application laid-open No. 9-123387, japanese patent application laid-open No. 9-131850, japanese patent application laid-open No. 9-171249, japanese patent application laid-open No. 9-171250, and European patent application No. 931647, which are published in 1992, are preferable.

Specific examples of the polymer constituting the thermoplastic polymer particles include homopolymers or copolymers of monomers such as ethylene, styrene, vinyl chloride, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, vinylidene chloride, acrylonitrile, vinylcarbazole, and acrylate or methacrylate having a polyalkylene structure, and mixtures thereof. Preferably, the resin composition includes a copolymer of polystyrene, styrene and acrylonitrile, or a polymethacrylic acid methyl group. The thermoplastic polymer particles preferably have an average particle diameter of 0.01 to 3.0. Mu.m.

Examples of the thermally reactive polymer particles include polymer particles having a thermally reactive group. The thermally reactive polymer particles form a hydrophobic region by crosslinking based on a thermal reaction and a change in functional group when crosslinking is performed.

The thermally reactive group in the polymer particles having a thermally reactive group may be a functional group which can form a chemical bond, and is preferably a polymerizable group, and examples thereof include an ethylenically unsaturated group (for example, acryloyl group, methacryloyl group, vinyl group, allyl group, or the like) which undergoes a radical polymerization reaction, a cationically polymerizable group (for example, vinyl group, vinyloxy group, epoxy group, oxetanyl group, or the like), an isocyanate group which undergoes an addition reaction or a block thereof, an epoxy group, a vinyloxy group, a functional group having an active hydrogen atom to be a reaction target (for example, amino group, hydroxyl group, carboxyl group, or the like), a carboxyl group which undergoes a condensation reaction, a hydroxyl group or an amino group to be a reaction target, an acid anhydride which undergoes a ring-opening addition reaction, an amino group or a hydroxyl group to be a reaction target, and the like.

As described in, for example, japanese patent application laid-open nos. 2001-277740 and 2001-277742, microcapsules containing at least a part of the components of the image recording layer are known. The constituent components of the image recording layer may be contained outside the microcapsules. A preferable embodiment of the microcapsule-containing image recording layer has a structure in which the microcapsules contain a hydrophobic component and the microcapsules contain a hydrophilic component.

The microgel (crosslinked polymer particles) can contain a part of the constituent components of the image recording layer on at least one of the surface or the inside thereof. In particular, from the viewpoint of image forming sensitivity and brushing resistance, a reactive microgel having a radical polymerizable group on the surface thereof is preferred.

In order to microencapsulate or microgel the constituent components of the image recording layer, a known method can be applied.

From the viewpoint of brush resistance, stain resistance and storage stability, the polymer particles are preferably those obtained by the reaction of a polyhydric isocyanate compound which is an adduct of a polyhydric phenol compound having 2 or more hydroxyl groups in the molecule and isophorone diisocyanate and a compound having active hydrogen.

The polyphenol compound is preferably a compound having a plurality of benzene rings having a phenolic hydroxyl group.

The compound having active hydrogen is preferably a polyol compound or a polyamine compound, more preferably a polyol compound, and still more preferably at least one compound selected from the group consisting of propylene glycol, glycerin, and trimethylolpropane.

The resin particles obtained by the reaction of the polyvalent isocyanate compound which is an adduct of a polyvalent phenol compound having 2 or more hydroxyl groups in the molecule and isophorone diisocyanate and a compound having an active hydrogen are preferably the polymer particles described in paragraphs 0032 to 0095 of jp 2012-206495 a.

In addition, from the viewpoint of brush resistance and solvent resistance, the polymer particles preferably have a hydrophobic main chain, and include i) a constituent unit having a cyano side group directly bonded to the hydrophobic main chain and ii) a constituent unit having a Pendant group (Pendant group) including a hydrophilic polyalkylene oxide segment.

The hydrophobic main chain preferably includes an acrylic resin chain.

Preferable examples of the cyano group-containing pendant group include- [ CH ] ₂ CH(C≡N)-]Or- [ CH ] ₂ C(CH ₃ )(C≡N)-]。

Further, the constituent unit having the cyano group pendant group can be easily derived from an ethylenically unsaturated monomer, such as acrylonitrile or methacrylonitrile, or from a combination of these.

The alkylene oxide in the hydrophilic polyalkylene oxide segment is preferably ethylene oxide or propylene oxide, and more preferably ethylene oxide.

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

Particles of resins described in paragraphs 0039 to 0068 of jp 2008-503365 a are preferable examples of particles of a resin having a hydrophobic main chain and containing i) a constituent unit having a cyano side group directly bonded to the hydrophobic main chain and ii) a constituent unit having a side group containing a hydrophilic polyalkylene oxide segment.

The average particle diameter of the polymer particles is preferably 0.01 to 3.0. Mu.m, more preferably 0.03 to 2.0. Mu.m, and still more preferably 0.10 to 1.0. Mu.m. In this range, good resolution and stability with time can be obtained.

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

Also, the average particle diameter in the present invention is a volume average particle diameter unless otherwise specified.

The content of the polymer particles is preferably 5 to 90% by mass with respect to the total mass of the image recording layer.

[ acid developer ]

The image recording layer used in the present invention preferably contains an acid developer.

The "acid color developer" used in the present invention is a compound having a color-developing property by being heated in a state of receiving an electron-accepting compound (for example, a proton such as an acid). Particularly preferred as the acid color developer is a colorless compound having a partial skeleton such as lactone, lactam, sultone, spiropyran (Spiropyran), ester, amide, etc., and rapidly opening or breaking the partial skeleton when it comes into contact with an electron-accepting compound.

As an example of such an acid color-developing agent, examples thereof include 3, 3-bis (4-dimethylaminophenyl) -6-dimethylaminophthalide (referred to as "crystal violet lactone"), 3-bis (4-dimethylaminophenyl) phthalide, 3- (4-dimethylaminophenyl) -3- (4-diethylamino-2-methylphenyl) -6-dimethylaminophthalide, 3- (4-dimethylaminophenyl) -3- (1, 2-dimethylindol-3-yl) phthalide, 3- (4-dimethylaminophenyl) -3- (2-methylindol-3-yl) phthalide, and 3, 3-bis (1, 2-dimethylindol-3-yl) -5-dimethylaminophthalide, 3-bis (1, 2-dimethylindol-3-yl) -6-dimethylaminophthalide, 3-bis (9-ethylcarbazol-3-yl) -6-dimethylaminophthalide, 3-bis (2-phenylindol-3-yl) -6-dimethylaminophthalide, 3- (4-dimethylaminophenyl) -3- (1-methylpyrrol-3-yl) -6-dimethylaminophthalide, 3-bis [ 1, 1-bis (4-dimethylaminophenyl) ethylene-2-yl ] -4,5,6, 7-tetrachlorophthalide, tetrachlorophthalide, 3, 3-bis [ 1, 1-bis (4-pyrrolidinophenyl) ethen-2-yl ] -4,5,6, 7-tetrabenzophthalide, 3-bis [ 1- (4-dimethylaminophenyl) -1- (4-methoxyphenyl) ethen-2-yl ] -4,5,6, 7-tetrachlorophthalide, 3-bis [ 1- (4-pyrrolidinophenyl) -1- (4-methoxyphenyl) ethen-2-yl ] -4,5,6, 7-tetrachlorophthalide, 3- [ 1, 1-bis (1-ethyl-2-methylindol-3-yl) ethen-2-yl ] -3- (4-diethylaminophenyl) phthalide, 3- [ 1, 1-bis (1-ethyl-2-methylindol-3-yl) ethen-2-yl ] -3- (4-N-ethyl-N-aminophenyl) phthalide, 3- (2-ethoxy-4-diethylaminophenyl) -3- (1-octyl-2-methylindol-3-octyl) -3- (3-methyl-2-octylphenyl) -3- (3-N-ethyl-N-aminophenyl) phthalide, 3- (2-ethoxy-4-diethylaminophenyl) -3- (1-octyl-2-methyl-3-octyl) -3-methyl-indolyl) phthalide, etc., 4, 4-bis-dimethylaminobenzopropanol benzyl ether, N-halophenyl-leuco auramine, N-2,4, 5-trichlorophenyl-leuco auramine, rhodamine-B-anilinolactam, rhodamine- (4-nitroanilino) lactam, rhodamine-B- (4-chloroanilino) lactam, and mixtures thereof 3, 7-bis (diethylamino) -10-benzoyloxazine, benzoyl leuco methylene blue, 4-nitrobenzoylmethylene blue, 3, 6-dimethoxyfluoran, 3-dimethylamino-7-methoxyfluoran, 3-diethylamino-6-methoxyfluoran, 3-diethylamino-7-methoxyfluoran 3-diethylamino-7-chlorofluoran, 3-diethylamino-6-methyl-7-chlorofluoran, 3-diethylamino-6, 7-diformfluoran, 3-N-cyclohexyl-N-N-butylamino-7-methylfluoran, 3-diethylamino-7-dibenzylaminofluoran, 3-diethylamino-7-octylaminofluoran, 3-diethylamino-7-di-N-hexylaminofluoran, 3-diethylamino-7-anilinofluoran, 3-diethylamino-7- (2 ' -fluoroanilino) fluoran, 3-diethylamino-7- (2 ' -chloroanilino) fluoran, 3-diethylamino-7- (3 ' -chloroanilino) fluoran, 3-diethylamino-7- (2 ',3' -Dichlorophenylamino) fluorane, 3-diethylamino-7- (3 ' -trifluoromethylphenylamino) fluorane, 3-di-N-butylamino-7- (2 ' -fluoroanilino) fluorane, 3-di-N-butylamino-7- (2 ' -chloroanilino) fluorane, 3-N-isopentyl-N-ethylamino-7- (2 ' -chloroanilino) fluorane, 3-N-N-hexyl-N-ethylamino-7- (2 ' -chloroanilino) fluorane, 3-diethylamino-6-chloro-7-anilinofluorane, 3-di-N-butylamino-6-chloro-7-anilinofluorane, 3-diethylamino-6-methoxy-7-anilinofluorane, 3-di-N-butylamino-6-ethoxy-7-anilinofluorane, 3-pyrrolidinyl-6-methyl-7-anilinofluorane, 3-hydropyridyl-6-methyl-7-anilinofluorane, 3-morpholino-6-methyl-7-anilinofluorane, 3-dimethylamino-6-dimethylamino-methyl-7-anilinofluorane, 3-dimethylamino-6-diethylamino-6-N-butylamino-7-anilinofluorane, 3-dimethylamino-6-dimethylamino-7-methylanilino, 3-6-diethylamino, 3-7-6-diethylamino, 3-diethylamino-6-fluoroaniline, 3-6-diethylamino-2, 3-diethylamino-6-2, and 3-6-N-fluoroaniline, 3-di-N-pentylamino-6-methyl-7-anilinofluoran, 3-N-ethyl-N-methylamino-6-methyl-7-anilinofluoran, 3-N-N-propyl-N-ethylamino-6-methyl-7-anilinofluoran, 3-N-N-butyl-N-methylamino-6-methyl-7-anilinofluoran, 3-N-N-butyl-N-ethylamino-6-methyl-7-anilinofluoran, 3-N-isobutyl-N-methylamino-6-methyl-7-anilinofluoran, 3-N-isobutyl-N-ethylamino-6-methyl-7-anilinofluoran, 3-N-isopentyl-N-ethylamino-6-methyl-7-anilinofluoran, 3-N-N-methylamino-N-hexyl-7-methyl-7-anilinofluoran, 3-N-cyclohexylamino-6-cyclohexylanilinofluoran Anilinofluoran, 3-N-cyclohexyl-N-hexylamino-6-methyl-7-anilinofluoran, 3-N-cyclohexyl-N-N-octylamino-6-methyl-7-anilinofluoran, 3-N- (2 '-methoxyethyl) -N-methylamino-6-methyl-7-anilinofluoran, 3-N- (2' -methoxyethyl) -N-ethylamino-6-methyl-7-anilinofluoran, 3-N- (2 '-methoxyethyl) -N-isobutylamino-6-methyl-7-anilinofluoran, 3-N- (2' -ethoxyethyl) -N-methylamino-6-methyl-7-anilinofluoran, 3-N- (2 '-ethoxyethyl) -N-ethylamino-6-methyl-7-anilinofluoran, 3-N- (3' -methoxypropyl) -N-methylamino-6-methyl-7-anilinofluoran, 3-N- (3 '-methoxypropyl) -N-ethylamino-6-methyl-7-anilinofluoran, 3-N- (3' -ethoxypropyl) -N-ethylamino-6-methyl-7-anilinofluoran, 3-N-6-methyl-anilinofluoran, 3-N- (3 ' -ethoxypropyl) -N-ethylamino-6-methyl-7-anilinofluoran, 3-N- (2 ' -tetrahydrofurfuryl) -N-ethylamino-6-methyl-7-anilinofluoran, 3-N- (4 ' -tolyl) -N-ethylamino-6-methyl-7-anilinofluoran, 3-diethylamino-6-ethyl-7-anilinofluoran, 3-diethylamino-6-methyl-7- (3 ' -tolylamino) fluoran, 3-diethylamino-6-methyl-7- (2 ',6' -xylylamino) fluoran, 3-di-N-butylamino-7- (2 ',6' -xylylamino) fluoran, 2-bis [ 4' - (3-N-cyclohexyl-N-methylamino-6-methylamino-7-ylaminophenyl ] propane, 3- [ 4' - (4-phenylamino ] phenyl ] fluoran, 5 ' - (4-dimethylamino) fluoran, 5-dimethylamino-6-methylamino-7-yl ] propane, etc., 3- (2-methyl-4-diethylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide, 3- (2-n-propoxycarbonylamino-4-di-n-propylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide, 3- (2-methylamino-4-di-n-propylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide, 3- (2-methyl-4-di-n-hexylaminophenyl) -3- (1-n-octyl-2-methylindol-3-yl) -4, 7-diazabephthalide, diazabephthalide 3, 3-bis (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3-bis (1-n-octyl-2-methylindol-3-yl) -4-azaphthalide, 3- (2-ethoxy-4-diethylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide, 3- (2-ethoxy-4-diethylaminophenyl) -3- (1-octyl-2-methylindol-3-yl) ) -4 or 7-azaphthalide, 3- (2-ethoxy-4-diethylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) -4 or 7-azaphthalide, 3- (2-hexyloxy-4-diethylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) -4 or 7-azaphthalide, 3- (2-ethoxy-4-diethylaminophenyl) -3- (1-ethyl-2-phenylindol-3-yl) -4 or 7-azaphthalide, 3- (2-butoxy-4-diethylaminophenyl) -3- (1-ethyl-2-phenylindol-3-yl) -4 or 7-azaphthalide 3-methyl-spiro-dinaphthopyran, 3-ethyl-spiro-dinaphthopyran, 3-phenyl-spiro-dinaphthopyran, 3-benzyl-spiro-dinaphthopyran, 3-methyl-naphtho- (3-methoxybenzo) spiropyran, 3-propyl-spiro-3-6-dibenzopyran (3-bis (9-dimethylamino-spiro-3' - (6-dimethylamino) fluorene, 3-bis (9-dimethylamino) spirofluorene Phthalides such as amino) phthalide, and other phthalides, 2 '-anilino-6' - (N-ethyl-N-isoamyl) amino-3 '-methylspiro [ isobenzofuran-1 (3H), 9' - (9H) xanthene-3-one, 2 '-anilino-6' - (N-ethyl-N- (4-methylphenyl)) amino-3 '-methylspiro [ isobenzofuran-1 (3H), 9' - (9H) xanthene ] -3-one, 3'-N, N-dibenzylamino-6' -N, N-diethylaminospiro [ isobenzofuran-1 (3H), 9'- (9H) xanthene ] -3-one, and 2' - (N-methyl-N-phenyl) amino-6 '- (N-ethyl-N- (4-methylphenyl)) aminospiro [ isobenzofuran-1 (3H), 9' - (9H) xanthene ] -3-one.

Among them, the acid color developer used in the present invention is preferably at least one compound selected from the group consisting of a spiropyran compound, a spirooxazine compound, a spirolactone compound, and a spirolactam compound, from the viewpoint of color developability.

The color of the colored pigment is preferably green, blue or black from the viewpoint of visibility.

As the acid-color developer, commercially available products such as ETAC, RED500, RED520, CVL, S-205, BLACK305, BLACK400, BLACK100, BLACK500, H-7001, GREEN300, NIRBLACK78, BLUE220, H-3035, BLUE203, ATP, H-1046, H-2114 (see above, fukui Yamada Chemical Co., ltd.), ANORGE-DCF, version-DCF, PINK-DCF, RED-DCF, BLMB, CVL, GREEN-DCF, TH-107 (see above, HODOYA GA CHEMICAL CO., LTD. Manufactured), ODB-2, ODB-4, ODB-250, ODB-BlackXV, BLUE-63, BLUE-502, HODOYA-169, ODG-2, yard-118, yard-40, and Crystal color lactone (see above, red Co., manufactured by Rekyo, ltd.), and crystal color lactone may be used. Among these commercially available products, ETAC, S-205, BLACK305, BLACK400, BLACK100, BLACK500, H-7001, GREEN300, NIRBLACK78, H-3035, ATP, H-1046, H-2114, GREEN-DCF, blue-63, GN-169 and crystal violet lactone are preferable because the visible light absorption of the film is good.

These acid color developers may be used alone, or two or more of them may be used in combination.

The content of the acid developer is preferably 0.5 to 10% by mass, and more preferably 1 to 5% by mass, based on the total mass of the image recording layer.

[ adhesive polymers other than the specific adhesive polymer ]

The image recording layer may contain a binder polymer other than the specific binder polymer (hereinafter, also referred to as "other binder polymer").

The specific binder polymer and the polymer corresponding to the polymer particles do not correspond to the other binder polymers. That is, the other binder polymer is a polymer that does not have at least one selected from the group consisting of a structural unit formed from an aromatic vinyl compound and a structural unit formed from an acrylonitrile compound and is not in a particle shape.

As the other binder polymer, a (meth) acrylic resin, a polyvinyl acetal resin, or a urethane resin is preferable.

Among them, the other binder polymers can be preferably used as well-known binder polymers used in the image-recording layer of the lithographic printing plate precursor. As an example, a binder polymer used for an on-press development type lithographic printing plate precursor (hereinafter, also referred to as an on-press development binder polymer) is described in detail.

The on-press developing binder polymer is preferably a binder polymer having an alkylene oxide chain. The adhesive polymer having an alkylene oxide chain may have a poly (alkylene oxide) site in the main chain or may have a side chain. The graft polymer may have a poly (alkylene oxide) in a side chain, or may be a block copolymer of a block material composed of a repeating unit containing a poly (alkylene oxide) and a block material composed of a repeating unit not containing a poly (alkylene oxide).

In the case where the main chain has a poly (alkylene oxide) site, a urethane resin is preferable. Examples of the polymer of the main chain in the case where the side chain has a poly (alkylene oxide) moiety include a (meth) acrylic resin, a polyvinyl acetal resin, a urethane resin, a polyurea resin, a polyimide resin, a polyamide resin, an epoxy resin, a polystyrene resin, a novolac type phenol resin, a polyester resin, a synthetic rubber, and a natural rubber, and a (meth) acrylic resin is particularly preferable.

Further, another preferable example of the other binder polymer is a polymer compound (hereinafter, also referred to as a star polymer compound) having a polymer chain in which a multifunctional thiol having 6 to 10 functions is bonded to a core through a thioether bond, and the polymer chain has a polymerizable group. As the star polymer compound, for example, a compound described in japanese patent laid-open publication No. 2012-148555 can be preferably used.

As described in jp 2008-195018 a, a star polymer compound has a polymerizable group such as an ethylenically unsaturated bond in a main chain or a side chain (preferably a side chain) for improving the film strength of an image portion. Crosslinking is formed between polymer molecules by the polymerizable group, and curing is promoted.

The polymerizable group is preferably an ethylenically unsaturated group such as a (meth) acrylic group, a vinyl group, an allyl group, or a vinylphenyl (styryl) group, or an epoxy group, and from the viewpoint of polymerization reactivity, a (meth) acrylic group, a vinyl group, and a vinylphenyl (styryl) group are more preferable, and a (meth) acrylic group is particularly preferable. These groups can be introduced into the polymer by a high molecular reaction and copolymerization. For example, a reaction between a polymer having a carboxyl group in a side chain and glycidyl methacrylate, or a reaction between a polymer having an epoxy group and a carboxylic acid having an ethylenically unsaturated group such as methacrylic acid can be used. These groups may be used simultaneously.

The molecular weight of the other binder polymer is preferably 2,000 or more, more preferably 5,000 or more, and still more preferably 10,000 to 300,000 in terms of polystyrene by GPC.

If necessary, a hydrophilic polymer such as polyacrylic acid or polyvinyl alcohol described in jp 2008-195018 a can be used in combination. Further, it is also possible to use both the lipophilic polymer and the hydrophilic polymer.

In the image recording layer used in the present invention, one kind of other binder polymer may be used alone, or two or more kinds may be used simultaneously.

The other binder polymer may be contained in any amount in the image recording layer, but the content of the binder polymer is preferably 1 to 90 mass%, more preferably 5 to 80 mass%, with respect to the total mass of the image recording layer.

In the case where the image recording layer of the present invention contains another binder polymer, the content of the other binder polymer is preferably more than 0% by mass and not more than 99% by mass, more preferably 20% by mass and not more than 95% by mass, and still more preferably 40% by mass and not more than 90% by mass, based on the total mass of the specific binder polymer and the other binder polymer.

[ chain transfer agent ]

The image recording layer used in the present invention may contain a chain transfer agent. The chain transfer agent helps to improve the brush resistance in lithographic printing plates.

The chain transfer agent is preferably a thiol compound, more preferably a thiol compound having 7 or more carbon atoms, and still more preferably a compound having a mercapto group on an aromatic ring (aromatic thiol compound), from the viewpoint of a boiling point (low volatility). The thiol compound is preferably a monofunctional thiol compound.

Specific examples of the chain transfer agent include the following compounds.

[ chemical formula 40]

[ chemical formula 41]

[ chemical formula 42]

[ chemical formula 43]

The chain transfer agent may be added in one kind alone, or two or more kinds may be used simultaneously.

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

[ sensitizer ]

The image recording layer may contain a sensitizer such as a phosphonium compound, a nitrogen-containing low molecular weight compound, or an ammonium group-containing polymer for improving the ink-receptive property. In particular, when the overcoat layer contains an inorganic layered compound, these compounds can function as a surface coating agent for the inorganic layered compound, and can suppress a decrease in the ink adhesion during printing with the inorganic layered compound.

The sensitizer is preferably used in combination with a phosphonium compound, a nitrogen-containing low-molecular-weight compound, and an ammonium group-containing polymer, and more preferably used in combination with a phosphonium compound, a quaternary ammonium salt, and an ammonium group-containing polymer.

Phosphonium compounds

Examples of the phosphonium compound include those described in Japanese patent laid-open Nos. 2006-297907 and 2007-050660. Specific examples thereof include tetrabutyliodophosphine, butyltriphenylphosphonium bromide, tetraphenylphosphonium bromide, 1, 4-bis (triphenylphosphine) butane = bis (hexafluorophosphate), 1, 7-bis (triphenylphosphine) heptane = sulfate, and 1, 9-bis (triphenylphosphine) nonane = naphthalene-2, 7-disulfonate.

Nitrogen-containing low molecular weight compounds

Examples of the nitrogen-containing low molecular weight compound include amine salts and quaternary ammonium salts. Furthermore, imidazolinium salts, benzimidazolinium salts, pyridinium salts and quinolinium salts are also included. Among them, quaternary ammonium salts and pyridinium salts are preferable. Specific examples thereof include tetramethylammonium = hexafluorophosphate, tetrabutylammonium = hexafluorophosphate, dodecyltrimethylammonium = p-toluenesulfonic acid, benzyltriethylammonium = hexafluorophosphate, benzyldimethyloctylammonium = hexafluorophosphate, benzyldimethyldodecylammonium = hexafluorophosphate, compounds described in paragraphs 0021 to 0037 of jp 2008-284858 a, compounds described in paragraphs 0030 to 0057 of jp 2009-090645 a, and the like.

Polymers containing ammonium groups

The ammonium group-containing polymer may have an ammonium group in its structure, and is preferably a polymer containing 5 to 80mol% of a (meth) acrylate having an ammonium group in a side chain as a copolymerization component. Specific examples thereof include polymers described in paragraphs 0089 to 0105 of Japanese patent application laid-open No. 2009-208458.

The value of reduced viscosity (unit: ml/g) of the ammonium group-containing polymer determined by the measurement method described in jp 2009-208458 a is preferably in the range of 5 to 120, more preferably in the range of 10 to 110, and particularly preferably in the range of 15 to 100. The reduced viscosity is preferably 10,000 to 150,000, more preferably 17,000 to 140,000, and particularly preferably 20,000 to 130,000 in terms of the weight average molecular weight (Mw).

Specific examples of the ammonium group-containing polymer are shown below.

(1) 2- (trimethylammonium) ethylmethacrylate = p-toluenesulfonate/3, 6-dioxaheptyl methacrylate copolymer (molar ratio 10/90, mw4.5 ten thousand)

(2) 2- (trimethylammonium) ethyl methacrylate = hexafluorophosphate/3, 6-dioxaheptyl methacrylate copolymer (molar ratio 20/80, mw6.0 ten thousand)

(3) 2- (ethyldimethylammonio) ethylmethacrylate = p-toluenesulfonate/hexyl methacrylate copolymer (molar ratio 30/70, mw4.5 ten thousand)

(4) 2- (trimethylammonium) ethyl methacrylate = hexafluorophosphate/2-ethylhexyl methacrylate copolymer (molar ratio 20/80, mw6.0 ten thousand)

(5) 2- (trimethylammonium) ethyl methacrylate = methyl sulfate/hexyl methacrylate copolymer (molar ratio 40/60, mw7.0 ten thousand)

(6) 2- (butyldimethylammonio) ethyl methacrylate = hexafluorophosphate/3, 6-dioxaheptyl methacrylate copolymer (molar ratio 25/75, mw6.5 ten thousand)

(7) 2- (butyldimethylammonio) ethylacrylate = hexafluorophosphate/3, 6-dioxaheptyl methacrylate copolymer (molar ratio 20/80, mw6.5 ten thousand)

(8) 2- (butyldimethylammonio) ethylmethacrylate = 13-ethyl-5, 8, 11-trioxa-1-heptadecane sulfonate/3, 6-dioxaheptyl methacrylate copolymer (molar ratio 20/80, mw7.5 ten thousand)

The content of the sensitizer is preferably 1 to 40.0% by mass, more preferably 2 to 25.0% by mass, and still more preferably 3 to 20% by mass, based on the total mass of the image recording layer.

[ other Components ]

The image recording layer may contain, as other components, a surfactant, a polymerization inhibitor, a higher fatty acid derivative, a plasticizer, inorganic particles, an inorganic layered compound, and the like. Specifically, reference can be made to the descriptions of paragraphs 0114 to 0159 of japanese patent application laid-open No. 2008-284817.

[ formation of image recording layer ]

The image recording layer in the lithographic printing plate precursor according to the present invention can be formed by, for example, dispersing or dissolving the above-described necessary components in a known solvent to prepare a coating liquid, applying the coating liquid on a support by a known method such as bar coating, and drying the coating liquid, as described in paragraphs 0142 to 0143 of jp 2008-195018 a. The amount of the image recording layer (solid content) after coating and drying is preferably 0.3g/m, although it varies depending on the application ² ～3.0g/m ² . Within this range, good sensitivity and good film properties of the image recording layer can be obtained.

As the solvent, a known solvent can be used. Specific examples of the organic solvent include water, acetone, methyl ethyl ketone (2-butanone), cyclohexane, ethyl acetate, dichloroethane, tetrahydrofuran, toluene, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, acetylacetone, cyclohexanone, diacetone alcohol, ethylene glycol monomethyl ether acetate, ethylene glycol ethyl ether acetate, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether acetate, 1-methoxy-2-propanol, 3-methoxy-1-propanol, methoxymethoxyethanol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, 3-methoxypropyl acetate, N-dimethylformamide, dimethyl sulfoxide, γ -butyrolactone, methyl lactate, and ethyl lactate. One solvent may be used alone, or two or more solvents may be used simultaneously. The solid content concentration in the coating liquid is preferably 1 to 50% by mass.

The amount of the image recording layer applied (solid content) after coating and drying varies depending on the application, but is preferably 0.3g/m from the viewpoint of obtaining good sensitivity and good film characteristics of the image recording layer ² ～3.0g/m ² 。

The film thickness of the image recording layer in the lithographic printing plate precursor according to the present invention is preferably 0.1 to 5.0. Mu.m, more preferably 0.3 to 2.0. Mu.m.

In the present invention, a slice cut in a direction perpendicular to the surface of the lithographic printing plate precursor is prepared for each layer thickness in the lithographic printing plate precursor, and the cross section of the slice is observed by a scanning microscope (SEM) to confirm the thickness.

< outer coating >

The lithographic printing plate precursor according to the present invention has an overcoat layer (also sometimes referred to as a "protective layer") on the surface of the image-recording layer on the side opposite to the support side.

In addition to the function of suppressing the image formation inhibition reaction by blocking oxygen, the overcoat layer also has the function of preventing the occurrence of scratches in the image recording layer and the ablation at the time of high-illuminance laser exposure.

Such a characteristic of the overcoat layer is described in, for example, U.S. Pat. No.3,458,311 and Japanese patent publication No. 55-049729. The low oxygen permeability polymer used in the overcoat layer can be used by appropriately selecting either a water-soluble polymer or a water-insoluble polymer, or can be used by mixing two or more kinds of polymers as necessary, and preferably contains a water-soluble polymer from the viewpoint of on-press developability.

In the present invention, the water-soluble polymer means a polymer which is obtained by dissolving 1g or more of a polymer in 100g of pure water at 70 ℃ and does not precipitate even when a solution obtained by dissolving 1g of the polymer in 100g of pure water at 70 ℃ is cooled to 25 ℃.

Examples of the water-soluble polymer used in the overcoat layer include polyvinyl alcohol, modified polyvinyl alcohol, polyvinyl pyrrolidone, water-soluble cellulose derivatives, polyethylene glycol, and poly (meth) acrylonitrile.

As the modified polyvinyl alcohol, an acid-modified polyvinyl alcohol having a carboxyl group or a sulfo group is preferably used. Specifically, modified polyvinyl alcohols described in Japanese patent application laid-open Nos. 2005-250216 and 2006-259137 are mentioned.

The water-soluble polymer preferably contains polyvinyl alcohol, and more preferably contains polyvinyl alcohol having a saponification degree of 50% or more.

The saponification degree is preferably 60% or more, more preferably 70% or more, and still more preferably 85% or more. The upper limit of the saponification degree is not particularly limited, and may be 100% or less.

The degree of saponification described above was determined according to JIS K6726: 1994, to be used as a reagent.

Further, as an embodiment of the overcoat layer, an embodiment including polyvinyl alcohol and polyethylene glycol can be preferably cited.

When the overcoat layer in the present invention contains a water-soluble polymer, the content of the water-soluble polymer is preferably 10 to 99% by mass, more preferably 30 to 95% by mass, and still more preferably 50 to 90% by mass, based on the total mass of the overcoat layer.

The overcoat layer may contain an inorganic layered compound in order to improve oxygen barrier properties. The inorganic layered compound is a particle having a thin flat plate shape, and examples thereof include mica groups such as natural mica and synthetic mica, and the formula: 3 MgO.4 SiO.H ₂ Talc represented by O, taeniolite, montmorillonite, saponite, hectorite, zirconium phosphate, and the like.

The inorganic layered compound preferably used is a mica compound. Examples of the mica compound include compounds represented by the formula: a (B, C) _2-5 D ₄ O ₁₀ (OH,F,O) ₂ Wherein A is any one of K, na and Ca, B and C are any one of Fe (II), fe (III), mn, al, mg and V, and D is Si or Al. Mica groups such as natural mica and synthetic mica.

In the mica group, examples of natural mica include muscovite, paragonite, phlogopite, biotite, and lepidolite. Examples of the synthetic mica include fluorophlogopite KMg ₃ (AlSi ₃ O ₁₀ )F ₂ Potassium tetrasilicic mica KMg _2.5 (Si ₄ O ₁₀ )F ₂ Iso-nonswelling mica and Na tetrafluoro silicon mica NaMg _2.5 (Si ₄ O ₁₀ )F ₂ Na or Li with mica (Na, li) Mg ₂ Li(Si ₄ O ₁₀ )F ₂ Montmorillonite series Na or Li hectorite (Na, li) _1/8 Mg _2/5 Li _1/8 (Si ₄ O ₁₀ )F ₂ And swelling mica. Also, synthetic smectites are useful.

Among the mica compounds, fluorine-based swellable mica is particularly useful. That is, the swelling synthetic mica has a structure consisting of

The metal atom substitution in the unit lattice layer of the thickness of the laminated structure is significantly larger than that of other clay minerals. As a result, a shortage of positive charge occurs in the lattice layer, and Li is adsorbed between the layers to compensate for the shortage ⁺ 、Na ⁺ 、Ca ²⁺ 、Mg ²⁺ And the like. These cations interposed between the layers are called exchangeable cations, and can be obtained by exchanging with a plurality of kinds of cations. In particular, the cation between the layers is Li ⁺ 、Na ⁺ In the case of (2), the ionic radius is small, so that the bonding between the lamellar lattices is weak, and the crystal is swollen to be large by water. When a shear force is applied in this state, the layered crystal lattice is easily broken, and a stable sol is formed in water. This tendency of the swellable synthetic mica is strong, and therefore, it is particularly preferably used.

From the viewpoint of diffusion control, the mica compound is preferably in a form having a smaller thickness, and the larger the planar size is, the better the smoothness of the coated surface and the transmittance of active light are not inhibited. Accordingly, the aspect ratio is preferably 20 or more, more preferably 100 or more, and particularly preferably 200 or more. The aspect ratio is a ratio of the length to the thickness of the particle, and can be measured, for example, by a projection view obtained from a micrograph of the particle. The larger the aspect ratio, the greater the effect obtained.

The average major axis of the particle diameter of the mica compound is preferably 0.3 to 20 μm, more preferably 0.5 to 10 μm, and particularly preferably 1 to 5 μm. The average thickness of the particles is preferably 0.1 μm or less, more preferably 0.05 μm or less, and particularly preferably 0.01 μm or less. Specifically, for example, in the case of swellable synthetic mica, which is a typical compound, the thickness is preferably about 1nm to 50nm and the planar size (major axis) is preferably about 1 μm to 20 μm.

The content of the inorganic layered compound is preferably 1 to 60% by mass, more preferably 3 to 50% by mass, based on the total solid content of the overcoat layer. In the case where a plurality of inorganic layered compounds are used simultaneously, the total amount of the inorganic layered compounds is also preferably the above content. Within the above range, the oxygen barrier property is improved and good sensitivity can be obtained. Further, the ink adhesion can be prevented from being lowered.

The overcoat layer may contain known additives such as a plasticizer for imparting flexibility, a surfactant for improving coatability, and inorganic particles for controlling surface slipperiness. The overcoat layer may contain a sensitizer described in the image recording layer.

The overcoat layer is applied by a known method. The coating amount (solid content) of the overcoat layer is preferably 0.01g/m ² ～10g/m ² More preferably 0.02g/m ² ～3g/m ² Particularly preferably 0.02g/m ² ～1g/m ² 。

The thickness of the overcoat layer in the lithographic printing plate precursor according to the present invention is preferably 0.01 to 5.0. Mu.m, and more preferably 0.1 to 1.0. Mu.m.

The thickness of the overcoat layer in the lithographic printing plate precursor according to the present invention is preferably 0.01 to 5 times, and more preferably 0.1 to 1 times the thickness of the image recording layer.

< undercoat layer >

The lithographic printing plate precursor according to the present invention preferably has an undercoat layer (also sometimes referred to as an intermediate layer) between the image-recording layer and the support. The undercoat layer enhances adhesion between the support and the image recording layer in the exposed portion, and facilitates peeling of the image recording layer from the support in the unexposed portion, and therefore, the undercoat layer contributes to improvement of the developability while suppressing a decrease in the brush resistance. In addition, in the case of infrared laser exposure, the undercoat layer functions as a heat-insulating layer, and thus there is an effect of preventing the heat generated by exposure from diffusing into the support and decreasing the sensitivity.

Examples of the compound used for the undercoat layer include polymers having an adsorptive group and a hydrophilic group that can be adsorbed on the surface of the support. In order to improve the adhesion to the image recording layer, a polymer having an adsorptive group, a hydrophilic group, and a crosslinkable group is preferable. The compound used in the undercoat layer may be a low molecular compound or a polymer. Two or more compounds used for the undercoat layer may be mixed and used as necessary.

When the compound used in the undercoat layer is a polymer, a copolymer of a monomer having an adsorptive group, a monomer having a hydrophilic group, and a monomer having a crosslinkable group is preferable.

As can be adsorbed on the surface of the support adsorption group, preferably phenol hydroxyl, carboxyl, -PO ₃ H ₂ 、-OPO ₃ H ₂ 、-CONHSO ₂ -、-SO ₂ NHSO ₂ -and-COCH ₂ COCH ₃ . The hydrophilic group is preferably a sulfo group or a salt thereof, or a salt of a carboxyl group. The crosslinkable group is preferably an acrylic group, a methacrylic group, an acrylamide group, a methacrylamide group, an allyl group or the like.

The polymer may have a crosslinkable group introduced by formation of a polar substituent of the polymer, a substituent having a charge opposite to the polar substituent, and a salt of a compound having an ethylenically unsaturated bond, and may further have a monomer other than the above, preferably a hydrophilic monomer copolymerized therewith.

Specifically, a silane coupling agent having an ethylene double bond reactive group capable of addition polymerization as described in Japanese patent application laid-open No. 10-282679 and a phosphorus compound having an ethylene double bond reactive group as described in Japanese patent application laid-open No. 2-304441 are preferable. It is also possible to preferably use a low-molecular or high-molecular compound having a crosslinkable group (preferably an ethylenically unsaturated bond group), a functional group that interacts with the surface of the support, and a hydrophilic group, which are described in each of Japanese patent application laid-open Nos. 2005-238816, 2005-125749, 2006-239867, and 2006-215263.

More preferred examples of the compound include high molecular polymers having an adsorptive group, a hydrophilic group and a crosslinkable group, which are capable of being adsorbed on the surface of a support, as described in Japanese patent application laid-open Nos. 2005-125749 and 2006-188038.

The content of the ethylenically unsaturated bond group in the polymer used in the undercoat layer is preferably 0.1mmol to 10.0mmol, more preferably 0.2mmol to 5.5mmol, per 1g of the polymer.

The weight average molecular weight (Mw) of the polymer used in the undercoat layer is preferably 5,000 or more, and more preferably 1 to 30 ten thousand.

The undercoat layer may contain, in addition to the compound for undercoat layer, a chelating agent, a secondary or tertiary amine, a polymerization inhibitor, an amino group or a functional group having a polymerization inhibiting action, and a compound having a group that interacts with the surface of the support (for example, 1, 4-diazabicyclo [2.2.2] octane ring (DABCO), 2,3,5, 6-tetrahydroxy-p-benzoquinone, chloranil, sulfophthalic acid, hydroxyethylethylenediaminetriacetic acid, dihydroxyethylethylenediaminediacetic acid, hydroxyethyliminodiacetic acid, and the like) in order to prevent contamination with time.

The undercoat layer is coated by a known method. The amount of the primer coating (solid content) is preferably 0.1mg/m ² ～100mg/m ² More preferably 1mg/m ² ～30mg/m ² 。

(method for manufacturing planographic printing plate and planographic printing method)

The lithographic printing plate precursor of the present invention can be subjected to image exposure and development treatment to produce a lithographic printing plate.

The method of manufacturing a lithographic printing plate according to the present invention preferably includes: a step of subjecting the on-press development type lithographic printing plate precursor according to the present invention to image-wise exposure (hereinafter, also referred to as "exposure step"); and a step of supplying at least one selected from the group consisting of printing inks and fountain solutions to the printing press to remove the image recording layer of the non-image portion (hereinafter, also referred to as "on-press development step").

The lithographic method according to the present invention preferably comprises: a step (exposure step) of image-wise exposing the on-press development type lithographic printing plate precursor according to the present invention; a step of supplying at least one selected from the group consisting of printing ink and dampening solution on a printing press to remove an image recording layer of a non-image portion, thereby producing a lithographic printing plate (on-press development step); and a step (printing step) of printing using the obtained lithographic printing plate.

Preferred embodiments of the method for producing a lithographic printing plate according to the present invention and the steps of the lithographic printing method according to the present invention will be described below in order. The lithographic printing plate precursor of the present invention can be developed with a developer.

Hereinafter, an exposure step and an on-press development step in the method for manufacturing a lithographic printing plate will be described, the exposure step in the method for manufacturing a lithographic printing plate according to the present invention is the same as the exposure step in the lithographic printing method according to the present invention, and the on-press development step in the method for manufacturing a lithographic printing plate according to the present invention is the same as the on-press development step in the lithographic printing method according to the present invention.

< Exposure Process >

The method for producing a lithographic printing plate according to the present invention preferably includes an exposure step of imagewise exposing the lithographic printing plate precursor according to the present invention to form exposed portions and unexposed portions. The lithographic printing plate precursor according to the present invention is preferably subjected to image-like exposure by laser exposure or laser scanning based on digital data using a transparent original image having a line image, a halftone image, or the like.

The wavelength of the light source is preferably 750nm to 1,400nm. As a light source of 750nm to 1,400nm,solid-state lasers and semiconductor lasers that radiate infrared rays are preferred. Regarding the infrared laser, the output is preferably 100mW or more, the exposure time per 1 pixel is preferably within 20 microseconds, and the amount of irradiation energy is preferably 10mJ/cm ² ～300mJ/cm ² . Also, in order to shorten the exposure time, a multi-beam laser apparatus is preferably used. The exposure mechanism may be any of an inner drum system, an outer drum system, a flat plate system, and the like.

As for the image exposure, a plate making machine or the like can be used and performed by a conventional method. In the case of on-press development, the lithographic printing plate precursor may be mounted on a printing press and then image-exposed on the printing press.

< on-machine development Process >

The method for producing a lithographic printing plate according to the present invention preferably includes an on-press development step of supplying at least one selected from the group consisting of printing ink and fountain solution to a printing press to remove an image recording layer in a non-image portion.

Hereinafter, an on-machine development method will be described.

[ on-machine development method ]

In the on-press development system, the image-exposed lithographic printing plate precursor is preferably prepared by supplying an oil-based ink and an aqueous component on a printing press to remove an image recording layer in a non-image part.

That is, when the lithographic printing plate precursor is subjected to image exposure, then directly mounted on a printing press without any development treatment or mounted on a printing press, then image exposure is performed on the printing press, and then an oil-based ink and an aqueous component are supplied and printing is performed, in the initial stage of the printing process, in the non-image portion, the image recording layer that has not been cured by either or both of the supplied oil-based ink and aqueous component is dissolved or dispersed and removed, and the hydrophilic surface is exposed in this portion. On the other hand, in the exposure portion, the image recording layer cured by exposure forms an oil-based ink-receiving portion having an oleophilic surface. The ink to be supplied to the printing surface may be an oil-based ink or an aqueous component, but the oil-based ink is preferably supplied at first from the viewpoint of preventing contamination due to the components of the image recording layer from which the aqueous component is removed. In this way, the lithographic printing plate precursor is subjected to on-press development on a printing press and is directly used for printing a plurality of sheets. As the oil-based ink and the aqueous component, a general printing ink for offset printing and a fountain solution are preferably used.

As the laser for image-wise exposure of the lithographic printing plate precursor according to the present invention, a laser having a light source wavelength of 300nm to 450nm or 750nm to 1,400nm is preferably used. In the case of a light source of 300nm to 450nm, it is preferable to use a lithographic printing plate precursor containing a sensitizing dye having an absorption maximum in the wavelength region in the image-recording layer, and to use the above-mentioned lithographic printing plate precursor as a light source of 750nm to 1,400nm. The light source of 300nm to 450nm is preferably a semiconductor laser.

< printing Process >

The lithographic printing method according to the present invention includes a printing step of supplying printing ink to a lithographic printing plate and printing a recording medium.

The printing ink is not particularly limited, and various known inks can be used as needed. Further, as the printing ink, oil-based ink or ultraviolet-curable ink (UV ink) can be preferably used.

In the printing step, a fountain solution may be supplied as needed.

The printing step may be performed after the on-press development step without stopping the printing press.

The recording medium is not particularly limited, and a known recording medium can be used as needed.

In the method for producing a lithographic printing plate of a lithographic printing plate precursor according to the present invention and the lithographic printing method according to the present invention, the entire surface of the lithographic printing plate precursor may be heated before exposure, during exposure, and during exposure to development, as necessary. Such heating promotes an image forming reaction in the image recording layer, and can provide advantages such as improvement in sensitivity and brush resistance and stabilization of sensitivity. The heating before development is preferably performed under mild conditions of 150 ℃ or lower. In this way, problems such as curing of the non-image portion can be prevented. The heating after the development is preferably performed under very strong conditions, and is preferably in the range of 100 to 500 ℃. Within the above range, a sufficient image-strengthening effect can be obtained, and problems such as deterioration of the support and thermal decomposition of the image portion can be suppressed.

Examples

The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. In the present example, "%" and "part" represent "% by mass" and "part by mass", respectively, unless otherwise specified. In addition, in the polymer compound, the molecular weight is a weight average molecular weight (Mw) and the ratio of the structural repeating units is a mole percentage unless otherwise specified. The weight average molecular weight (Mw) is a value measured as a polystyrene conversion value by a Gel Permeation Chromatography (GPC) method.

(examples 1 to 30 and comparative examples 1 to 7)

< production of support body >

In order to remove the rolling oil on the surface of an aluminum plate (material JIS A1050) having a thickness of 0.3mm, after degreasing treatment at 50 ℃ for 30 seconds using a10 mass% sodium aluminate aqueous solution, 3 bundled nylon bristles having a bundle diameter of 0.3mm and a pumice-water suspension (specific gravity 1.1 g/cm) having a median particle diameter of 25 μm were used ³ ) The surface of the aluminum plate was granulated and thoroughly washed with water. The aluminum plate was immersed in a 25 mass% aqueous solution of sodium hydroxide at 45 ℃ for 9 seconds to be etched and washed with water, and then immersed in a20 mass% aqueous solution of nitric acid at 60 ℃ for 20 seconds to be washed with water. The etching amount of the grained surface was about 3g/m ² 。

Next, the electrochemical graining treatment was continuously performed by using an alternating voltage of 60 Hz. The electrolyte was a1 mass% nitric acid aqueous solution (containing 0.5 mass% aluminum ions), and the liquid temperature was 50 ℃. As for the ac power waveform, a trapezoidal rectangular wave ac in which the time TP for the current value to reach the peak value from zero is 0.8ms, the duty ratio is 1The electrode was treated with electrochemical roughening as a counter electrode. Ferrite is used as the auxiliary anode. The current density was 30A/dm at the peak of the current ² And 5% of the current from the power supply was shunted to the auxiliary anode. The electric quantity in the nitric acid electrolysis is 175C/dm when the aluminum plate is taken as an anode ² . Then, water washing was performed by a nebulizer.

Then, using an aqueous solution (containing 0.5 mass% of aluminum ions) of 0.5 mass% hydrochloric acid and an electrolyte solution having a liquid temperature of 50 ℃ and an electric energy of 50℃/dm when an aluminum plate is used as an anode ² The electrochemical graining treatment was performed by the same method as in the nitric acid electrolysis under the conditions of (1) and then, water washing was performed by a sprayer.

Then, a 15 mass% sulfuric acid aqueous solution (containing 0.5 mass% of aluminum ions) was applied to the aluminum plate as an electrolytic solution at a current density of 15A/dm ² Form 2.5g/m ² The coating film was then subjected to direct current anodic oxidation, washed with water, and dried to prepare a support. The average pore diameter (surface average pore diameter) in the surface layer of the anodic oxide film was 10nm.

The pore diameter in the surface layer of the anodic oxide film was measured by observing the surface at a magnification of 15 ten thousand times using an ultra-high resolution SEM (scanning electron microscope, hitachi, S-900 manufactured by ltd.) without performing a deposition treatment for imparting conductivity at a relatively low acceleration voltage of 12V, and randomly extracting 50 pores and calculating an average value. The standard deviation is ± 10% or less of the mean.

< formation of lithographic printing plate precursor >

A primer coating solution (1) having the following composition was applied to the support so that the dry coating weight became 20mg/m ² And dried at 100 ℃ for 30 seconds by an oven, thereby producing a support having a primer layer.

The following image-recording layer coating liquid (1) was bar-coated on the undercoat layer and dried at 100 ℃ for 60 seconds to give a dry coating weight of 0.60g/m ² (film thickness = about 0.60 μm), thereby obtaining a lithographic printing plate precursor.

Thereafter, the following was coated on the image recording layerA topcoat coating solution (1) composed of and dried at 100 ℃ for 60 seconds to give a dry coating weight of 1.0g/m ² An overcoat layer (film thickness = about 1.0 μm), thereby obtaining a lithographic printing plate precursor.

In example 7, example 21, example 24, and example 27, the dry coating amounts were changed so that the contents of the respective components in the overcoat layer became values described in the contents described in table 1.

[ primer liquid (1) ]

The following undercoating compound 1:0.18 part

Methanol: 55.24 parts

Distilled water: 6.15 parts of

Synthesis of priming Compound 1

< purification of monomer M-1 >)

LIGHT ESTER P-1M (2-methacryloyloxyethyl acid phosphate, KYOEISHA CHE mica co., ltd., manufactured) 420 parts, diethylene glycol dibutyl ether 1,050 parts, and distilled water 1,050 parts were added to a separatory funnel, vigorously stirred, and then allowed to stand. After discarding the upper layer, 1,050 parts of diethylene glycol dibutyl ether was added thereto, and the mixture was vigorously stirred and then allowed to stand. The upper layer was discarded to obtain 1,300 parts of an aqueous solution of the monomer M-1 (10.5% by mass in terms of solid content).

< Synthesis of undercoating Compound 1 >

53.73 parts of distilled water and 3.66 parts of monomer M-2 shown below were added to a three-necked flask, and the temperature was raised to 55 ℃ under a nitrogen atmosphere. Subsequently, the dropwise addition solution 1 shown below was added dropwise over 2 hours, and after stirring for 30 minutes, 0.386 part of 2,2' -azobis [2- (2-imidazolin-2-yl) propane ] disulfate dihydrate (VA-046B, manufactured by FUJIFILM Wako Pure Chemical Corporation) was added, and the mixture was heated to 80 ℃ and stirred for 1.5 hours. After the reaction solution was returned to room temperature (25 ℃), a 30 mass% aqueous solution of sodium hydroxide was added to adjust the pH to 8.0, and 0.005 part of 4-hydroxy-2, 6-tetramethylpiperidine-1-oxyl (4-OH-TEMPO, aldrich) was added. Through the above operations, 180 parts of an aqueous solution of the undercoating compound 1 was obtained. The weight average molecular weight (Mw) as a polyethylene glycol converted value obtained by a Gel Permeation Chromatography (GPC) method was 17 ten thousand.

[ chemical formula 44]

Dripping solution 1

Aqueous solution of the above monomer M-1: 87.59 parts of

The above monomer M-2:14.63 parts

VA-046B (2, 2' -azobis [2- (2-imidazolin-2-yl) propane ] disulfate dihydrate, manufactured by FUJIFILM Wako Pure Chemical Corporation): 0.386 parts of

Distilled water: 20.95 parts

< coating liquid for image recording layer (1) >

Infrared absorber 1 (compound of the following structure): 0.030 parts of

Di-p-triiodonium PF ₆ ^- Salt (manufactured by Aldrich Co.): 0.032 portion

NK ester A-9300 (Shin-Nakamura Chemical Co., ltd.): 0.100 part

A-DPH (Shin-Nakamura Chemical Co., ltd.): 0.100 part

BYK306 (Byk Chemie Co.): 0.008 portion

1-methoxy-2-propanol: 8.609 portions

Methyl ethyl ketone: 1.091 parts

Specific binder polymers as described in table 1 or table 2: the amounts shown in Table 1 or Table 2

Specific development accelerators described in table 1 or table 2: the amounts shown in Table 1 or Table 2

[ chemical formula 45]

< overcoat coating liquid >

Water-soluble polymers described in table 1 or table 2: the amounts shown in Table 1 or Table 2

Surfactant (RAPISOL (registered trademark) A-80, manufactured by NOF CORPORATION): 0.01 part by mass

Water: the whole amount becomes 10 parts by mass

(examples 31 and 32)

A lithographic printing plate precursor was obtained in the same manner as in example 1, except that the infrared absorber 1 in example 1 was changed to the infrared absorber described in table 1.

[ Table 2]

In Table 1, the values in the columns "P-1" to "P-3" of the specific binder polymers indicate the contents (parts by mass) of the following P-1 to P-3. The expression "-" indicates that the corresponding compound is not contained.

In Table 1, the values in the column "A-1" to "A-4" of a specific development accelerator represent the contents (parts by mass) of the following A-1 to A-4. The expression "-" indicates that the corresponding compound is not contained.

In table 1, the descriptions in the columns "type" and "content" of the water-soluble polymer indicate the type and content (parts by mass) of the water-soluble polymer used, respectively.

In table 2, the descriptions in the columns of "type" and "content" of the specific binder polymer indicate the type and content (parts by mass) of the specific binder polymer used, respectively. In table 2, the descriptions in the columns of "type" and "content" of the specific development accelerator respectively indicate the type and content (parts by mass) of the specific binder polymer used.

In table 2, the descriptions in the columns "type" and "content" of the water-soluble polymer indicate the type and content (parts by mass) of the water-soluble polymer used, respectively.

The details of the compounds shown in table 1 or table 2 are as follows.

< Special adhesive Polymer >

[ Synthesis of Binder Polymer P-1 ]

300g of methyl ethyl ketone was added to a three-necked flask, and the mixture was heated to 80 ℃ under a nitrogen stream. To the reaction vessel, a mixed solution composed of 50.0g of the following compound (1), 50.0g of the following compound (2), 0.7g of AIBN (azobisisobutyronitrile), and 100g of methyl ethyl ketone was added dropwise over 30 minutes. After the completion of the dropwise addition, the reaction was continued for 7.5 hours. Then, 0.3g of AIBN was added and the reaction was continued for 12 hours. After the reaction was completed, the reaction solution was cooled to room temperature to obtain P-1. The weight average molecular weight of the obtained P-1 was 75,000.

[ chemical formula 46]

[ Synthesis of Binder Polymer P-2 ]

300g of methyl ethyl ketone was added to a three-necked flask, and the mixture was heated to 80 ℃ under a nitrogen stream. To the reaction vessel, a mixed solution composed of 70.0g of the compound (1), 20.0g of the compound (2), 10.0g of the compound (3), 0.7g of AIBN0 and 100g of methyl ethyl ketone was added dropwise over 30 minutes. After the completion of the dropwise addition, the reaction was continued for 7.5 hours. Then, AIBN0.3g was added, and the reaction was continued for 12 hours. After the reaction was completed, the reaction solution was cooled to room temperature to obtain P-2. The weight average molecular weight of the obtained P-2 was 50,000.

[ chemical formula 47]

[ Synthesis of adhesive Polymer P-3 ]

300g of methyl ethyl ketone was added to a three-necked flask, and the mixture was heated to 80 ℃ under a nitrogen stream. A mixed solution of 90.0g of the above-mentioned compound (1), 40.0g of the above-mentioned compound (2), 10.0g of the above-mentioned compound (3), 0.7g of AIBN and 100g of methyl ethyl ketone was added dropwise to the reaction vessel over 30 minutes. After the completion of the dropwise addition, the reaction was continued for 7.5 hours. Then, 0.3g of AIBN was added and the reaction was continued for 12 hours. After the reaction was completed, the reaction solution was cooled to room temperature to obtain P-3. The weight average molecular weight of the obtained P-3 was 60,000.

[ comparison with specific Binder polymers ]

Klucel 99M: hydroxypropyl cellulose manufactured by Hurcles

< Special developing accelerator >

A-1: tris (2-hydroxyethyl) isocyanurate, polar term for SP value =6.4

A-2: polar terms of trimethylglycine, SP value =6.5

A-3: the polar terms of the compound a-3, SP values of the following structure have values =8.1

A-4: hydroxypropylmethylcellulose, value of polar term of SP value =11.0 (60 SH, shin-Etsu Chemical co., ltd.)

[ chemical formula 48]

[ comparison with specific development promoters ]

NK ester A-9300: ethoxylated isocyanuric acid triacrylate, value of polar term of SP value =1.8

A compound A: PF of a compound of the structure ₆ ^- Polar terms of salt, SP value =26.8

[ chemical formula 49]

< Water-soluble Polymer >

PVA105: polyvinyl alcohol (saponification degree =98% -99%), KURARAY co, ltd

PVA205: polyvinyl alcohol (saponification degree =86.5% -89.0%), KURARAY co

The PVA405: polyvinyl alcohol (saponification degree =80.0% -83.0%), KURARAY co

LM-10HD: polyvinyl alcohol (saponification degree =38% -42%), KURARAY co

LM-20: polyvinyl alcohol (saponification degree =38% -42%), KURARAY co

LM-25: polyvinyl alcohol (saponification degree =33% -38%), KURARAY co

PEG4000: polyethylene glycol, tokyo Chemical Industry Co., ltd

[ Infrared absorber ]

The infrared absorbers in table 1 are described in detail below.

Infrared absorber 2: a compound of the structure

Infrared absorber 3: a compound of the structure

[ chemical formula 50]

< evaluation >

[ outer layer scratch resistance ]

Using the lithographic printing plate precursors obtained in each example or comparative example, in a scratch test: the surface of each lithographic printing plate precursor was scanned with a 0.1mm diameter Sapphire stylus (Sapphire needle) from 5g to 100g at 5g intervals for a scratch test (measured by a Shinto Scientific co., ltd.

The lithographic printing plate precursor after the scratch test was placed on a Kodak (registered trademark) Trendsetter800II Q uvatum plate making machine (830 nm), and exposed to light using an Infrared (IR) laser at 830nm so that the scratched portion covered an exposed image and a non-image portion of a chart including a solid image and 50% dots of 20 μm dot frequency modulated screen. The obtained exposed original plate was mounted on a plate cylinder of a printer LITHONE 26 manufactured by KOMORI Corporation without being subjected to a development process. After on-press development was performed by supplying fountain solution and ink by the standard automatic printing start method of LITHRONE26 using Ecity-2 (manufactured by Fujifilm Corporation)/tap water =2/98 (volume ratio) fountain solution and Space Color fusion G ink (manufactured by DIC Graphics Corporation), 500 sheets were printed on Tokubishi Art (continuous amount: 76.5 kg) paper at a printing speed of 10,000 sheets per hour.

The maximum load at which no damage of the image portion or no development failure of the non-image portion or ink contamination due to scratch occurred on the 500 th printed matter obtained was evaluated as the outer layer scratch resistance (g) and is shown in table 3. The greater the maximum load, the more excellent the scratch resistance of the lithographic printing plate.

[ inking Property (ink inking Property) ]

The lithographic printing plate precursors obtained in the respective examples or comparative examples were used, and development was performed by the same method as the development method in the above-described outer layer scratch resistance, except that the above-described scratch test was not performed. The lithographic printing plate after the above development treatment was mounted on a plate cylinder of a printer LIT HRONE26 manufactured by KOMORI Corporation. The fountain solution and ink were supplied and printing was started by the standard automatic printing start method of LITHONE 26 using a fountain solution of Ecoli-2 (manufactured by Fujifilm Corporation)/tap water =2/98 (volume ratio) and a value-G (N) ink (manufactured by DIC CORPORATION), and 100 sheets were printed on Tokubishi Art (continuous volume: 76.5 kg) paper at a printing speed of 10,000 sheets per hour.

The number of sheets of printing paper required until the ink density in the area of the exposed portion of the image recording layer reached a predetermined standard density was measured as the initial ink receptivity, and is shown in table 3.

[ on-machine developability ]

The lithographic printing plate precursors of the examples and comparative examples were exposed to light at an outer drum rotation speed of 1000rpm (emissions per minute) and a laser output of 70% with a resolution of 2400dpi (1 inch =2.54 cm) using a lux PLATESE tte T-6000III manufactured by Fujifilm Corporation equipped with an infrared semiconductor laser. Set to a graph containing a solid image and 50% dots of 20 μm dot FM screening in the exposure image.

The obtained exposed original plate was mounted on a plate cylinder of a printer LITHONE 26 manufactured by KOMORI Corporation without being subjected to a development process. After on-machine development was performed by supplying fountain solution and ink by the standard automatic printing start method of LITHONE 26 using Ecity-2 (manufactured by Fujifilm Corporation)/tap water =2/98 (volume ratio) fountain solution and Space Color Fusion G ink (manufactured by DIC Graphics Corporation), 500 sheets were printed on Tokubishi Art (continuous amount: 76.5 kg) paper at a printing speed of 10,000 sheets per hour.

The number of sheets of printing paper required until the unexposed portion of the image recording layer was developed on the printing press and the ink was not transferred to the non-image portion was measured as on-press developability, and is shown in table 3.

[ residue of on-machine development ]

In the evaluation of the on-press developability, the presence or absence of generation of a residue adhering to the dampening roller was evaluated, the generation of a residue was C, the generation of a small amount of residue was confirmed to be B, and the generation of no residue was a, and these results are shown in table 3.

[ Table 3]

From the results shown in table 3, it is understood that the lithographic printing plate precursors according to the examples can provide lithographic printing plates which are suppressed in the generation of on-press development residues and excellent in on-press developability, inking properties and scratch resistance.

The disclosures of Japanese patent application Nos. 2018-142864, 2018, 7-30, and 2018, 10-31, 2018-205747, which are incorporated herein by reference in their entireties.

All documents, japanese patent applications, and technical standards described in the present specification are incorporated by reference in the present specification in the same manner as in the case where each of the documents, japanese patent applications, and technical standards incorporated by reference is specifically and individually described.

Claims

1. An on-press developable lithographic printing plate precursor comprising a support, an image recording layer and an overcoat layer in this order,

the image recording layer comprises a binder polymer and a development accelerator,

the binder polymer has a structural unit formed of an aromatic vinyl compound and a structural unit formed of an acrylonitrile compound,

the film thickness of the overcoat layer is thicker than the film thickness of the image recording layer.

2. The on-press developable lithographic printing plate precursor according to claim 1,

the image recording layer further contains a polymerizable compound, and the content of the binder polymer is more than 0 mass% and 400 mass% or less with respect to the total mass of the polymerizable compound.

3. The on-press developable lithographic printing plate precursor according to claim 1 or 2,

the outer coating comprises a water soluble polymer.

4. The on-press developable lithographic printing plate precursor according to claim 3,

the water-soluble polymer contains polyvinyl alcohol having a saponification degree of 50% or more.

5. The on-press developable lithographic printing plate precursor according to claim 1 or 2,

the development accelerator is a compound having a cyclic structure.

6. The on-press developable lithographic printing plate precursor according to claim 5,

the compound having a cyclic structure has a hydroxyl group.

7. The on-press developable lithographic printing plate precursor according to claim 1 or 2,

the development accelerator is an onium compound.

8. The on-press developable lithographic printing plate precursor according to claim 1 or 2, which contains two or more compounds as the development accelerator.

9. The on-press developable lithographic printing plate precursor according to claim 1 or 2,

the binder polymer also has structural units formed from N-vinylpyrrolidone.

10. The on-press developable lithographic printing plate precursor according to claim 1 or 2,

the image recording layer further comprises an infrared absorber.

11. The on-press developable lithographic printing plate precursor according to claim 10,

the infrared absorber is decomposed by infrared exposure.

12. The on-press developing type lithographic printing plate precursor according to claim 10,

the infrared absorber is decomposed by heat, electron movement, or both of the heat and the electron movement due to infrared exposure.

13. The on-press developable lithographic printing plate precursor according to claim 10,

the infrared absorbent is cyanine pigment.

14. The on-press developable lithographic printing plate precursor according to claim 10,

the infrared absorber is a compound represented by the following formula 1,

in the formula 1, R ¹ Represents R by infrared ray exposure ¹ -L bond-breaking group, R ₁₁ ～R ₁₈ Independently represent a hydrogen atom, a halogen atom, -Ra, -ORb, -SRc or-NRdRe, ra to Re independently represent a hydrocarbon group, A ₁ 、A ₂ And a plurality of R ₁₁ ～R ₁₈ Optionally linked to form a monocyclic or polycyclic ring, A ₁ And A ₂ Each independently represents an oxygen atom, a sulfur atom or a nitrogen atom, n ₁₁ And n ₁₂ Each independently represents an integer of 0 to 5, wherein n ₁₁ And n ₁₂ Is 2 or more, n ₁₃ And n ₁₄ Each independently represents 0 or 1, L represents an oxygen atom, a sulfur atom or-NR ¹⁰ -，R ¹⁰ Represents a hydrogen atom, an alkyl group or an aryl group, and Za represents a counter ion for neutralizing a charge.

15. The on-press developing type lithographic printing plate precursor according to claim 14,

r in the formula 1 ¹ Is a group represented by the following formula 2,

in the formula 2, R ^Z Represents an alkyl group, and the wavy line portion represents a bonding site with a group represented by L in the formula 1.

16. A method of making a lithographic printing plate comprising:

a step of image-wise exposing the on-press development type lithographic printing plate precursor according to any one of claims 1 to 15; and

17. A lithographic method, comprising:

a step of subjecting the on-press development type lithographic printing plate precursor according to any one of claims 1 to 15 to image-wise exposure;

and a step of printing by the obtained lithographic printing plate.