CN112512828A

CN112512828A - On-press developable lithographic printing plate precursor, method for producing lithographic printing plate, and lithographic printing method

Info

Publication number: CN112512828A
Application number: CN201980050971.8A
Authority: CN
Inventors: 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: 2021-03-16
Anticipated expiration: 2039-07-29
Also published as: WO2020027071A1; JPWO2020027071A1; CN112512828B; JP7062064B2

Abstract

The invention provides an on-press development type lithographic printing plate precursor, a plate making method of 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 sequentially comprises a support, an image recording layer and an overcoat layer, the image recording layer comprises a binder polymer and a compound A with SP value less than 18.0, the binder polymer comprises a structural unit formed by an aromatic vinyl compound and a structural unit formed by an acrylonitrile compound, and the film thickness of the overcoat layer is 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, environmental problems associated with waste liquid accompanying wet processing such as development processing have become apparent because of growing interest in the global environment.

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 method of developing a photosensitive lithographic printing plate material used as a printing plate by exposing and developing a photosensitive lithographic printing plate material, which is obtained by coating a grained aluminum support with a photopolymerizable photosensitive layer and an overcoat layer, based on digitally converted data, and a solid alkali developer for a photosensitive lithographic printing plate material characterized in that after exposure, the photosensitive lithographic printing plate material is developed with a developer obtained by dissolving the solid alkali developer.

Patent document 2 describes a plate making method for a lithographic printing plate, which is characterized by sequentially including: an exposure step of image-exposing a positive-working lithographic printing plate precursor for infrared laser, which is obtained by providing a positive-working recording layer on a support; and a developing step of performing development using an alkaline aqueous solution containing a betaine surfactant and having a pH of 8.5 to 10.8, wherein the positive recording layer contains (component A) a copolymer comprising a structural unit derived from (meth) acrylonitrile and a structural unit derived from styrene, (component B) a water-insoluble and alkali-soluble resin, and (component C) an infrared absorber, and the solubility in the alkaline aqueous solution is improved by exposure or heating.

Patent document 3 describes a device capable of forming an image, which comprises a lithographic substrate and an image-formable layer disposed on the substrate, the image-formable layer containing a) a radical polymerizable component; b) an initiator system capable of generating radicals sufficient to initiate a polymerization reaction upon exposure to the image-forming radiation; and c) a polymeric adhesive having a hydrophobic main chain and comprising i) a constituent unit having a cyano group as a side group directly bonded to the hydrophobic main chain and ii) a constituent unit having a side group comprising a hydrophilic poly (alkylene oxide) partition.

Patent document 1: japanese patent laid-open publication No. 2004-361549

Patent document 2: japanese patent laid-open publication No. 2011-

Patent document 3: japanese patent laid-open publication No. 2013-047004

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.

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") is superior in the inhibition of development residue during on-press development, compared to the lithographic printing plate precursors described in patent documents 1 to 3.

An object to be solved by an embodiment of the present invention is to provide an on-press development type lithographic printing plate precursor having excellent development residue suppression property in on-press development, 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.

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 compound A having an SP value of less than 18.0,

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

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 contains 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 developable lithographic printing plate precursor according to any one of the above < 1 > to < 4 >, wherein the above compound A is a sensitizer.

< 6 > the on-press developable lithographic printing plate precursor according to any one of the above < 1 > to < 5 >, wherein the molecular weight of the above compound A is 2,000 or more.

< 7 > the on-press developable lithographic printing plate precursor according to any one of the above < 1 > to < 5 >, wherein the molecular weight of the above compound A is less than 2,000.

< 8 > the on-press developable lithographic printing plate precursor according to any one of the above < 1 > to < 7 >, wherein the above compound A is an onium compound.

< 9 > the on-press developable lithographic printing plate precursor according to < 8 > above, wherein the onium compound contains at least one selected from the group consisting of the ammonium compound and the phosphonium compound.

< 10 > the on-press developable lithographic printing plate precursor according to any one of the above < 1 > to < 9 > containing two or more of the above-mentioned compound a.

< 11 > the on-press developable lithographic printing plate precursor according to any one of the above < 1 > to < 10 >, wherein the above binder polymer further has a structural unit formed from N-vinylpyrrolidone.

< 12 > the on-press developable lithographic printing plate precursor according to any one of the above < 1 > to < 11 >, wherein the image recording layer further comprises an infrared absorber.

< 13 > the on-press developable lithographic printing plate precursor according to the above < 12 >, wherein the infrared absorber is an infrared absorber decomposed by infrared exposure.

< 14 > the on-press developable lithographic printing plate precursor according to the above < 12 > or < 13 >, 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.

< 15 > the on-press developable lithographic printing plate precursor according to any one of the above < 12 > to < 14 >, wherein the infrared absorber is a cyanine dye.

< 16 > the on-press developable lithographic printing plate precursor according to any one of the above < 12 > to < 115 >, wherein the infrared absorber is a compound represented by the following formula 1.

[ chemical formula 1]

In the formula 1, R¹Represents R by infrared ray exposure¹-L bond-breaking group, R₁₁～R₁₈Independently represent a hydrogen atom, a halogen atom, -Ra, -ORb, -SRc or-NRdRe, Ra to Re independently represent a hydrocarbon group, A₁、A₂And a plurality of R₁₁～R₁₈May be linked to form a monocyclic or polycyclic ring, A₁And A₂Each independently represents an oxygen atom, a sulfur atom or a nitrogen atom, n₁₁And n₁₂Each independently represents an integer of 0 to 5, wherein n₁₁And n₁₂Is 2 or more, n₁₃And n₁₄Each independently represents 0 or 1, L represents an oxygen atom, a sulfur atom or-NR¹⁰-，R¹⁰Represents a hydrogen atom, an alkyl group or an aryl group, and Za represents a counter ion for neutralizing a charge.

< 17 > the on-press developable lithographic printing plate precursor according to the above < 16 >, wherein R in the above formula 1¹Is a group represented by the following formula 2.

[ chemical formula 2]

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

< 18 > a method for producing a lithographic printing plate, comprising: image-wise exposing the on-press development type lithographic printing plate precursor described in any of the above-mentioned < 1 > to < 17 >; 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.

< 19 > a lithographic method comprising: image-wise exposing the on-press development type lithographic printing plate precursor described in any of the above-mentioned < 1 > to < 17 >;

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, an on-press development type lithographic printing plate precursor having excellent development residue suppression performance in on-press development, 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 can be provided.

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 in a meaning including 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 "weight%" 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 a plurality of substances or structural units corresponding to each constituent in the composition or each structural unit in the polymer are present, unless otherwise specified, the amount of each structural unit in each constituent 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 printing 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 needed, 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 developable lithographic printing plate precursor of the present invention comprises a support, an image recording layer and an overcoat layer in this order, the image recording layer contains a binder polymer and a compound A having an SP value of less than 18.0, the binder polymer has a structural unit comprising an aromatic vinyl compound and a structural unit comprising an acrylonitrile compound, and the overcoat layer has a film thickness larger than that of the image recording layer.

As a result of intensive studies, the present inventors have found that a lithographic printing plate precursor having excellent development residue suppression performance 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.

It is presumed that the lithographic printing plate precursor according to the present invention has an overcoat layer which contains a binder polymer having a structural unit formed from an aromatic vinyl compound and a structural unit formed from an acrylonitrile compound (hereinafter, also referred to as "specific binder polymer") and a compound a having an SP value of less than 18.0 (hereinafter, also referred to as "specific compound a"), and which has a film thickness thicker than that of the image recording layer, and therefore, the development residue inhibition property is excellent due to the synergistic action of all these structural elements, but the mechanism thereof is not clear.

In the lithographic printing plate precursor described in patent document 2, there is no description nor suggestion about the case where the plate has an overcoat layer having a film thickness larger than that of the image recording layer and about the specific compound a, and there is room for improvement in the inhibition of on-press development residue.

The lithographic printing plate precursors described in patent documents 1 and 3 are neither described nor suggested for the specific compound a, and have poor on-press development residue inhibition properties.

Further, it is considered that a lithographic printing plate having excellent ink-receptivity (hereinafter, also simply referred to as "ink-receptivity") 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 the specific binder polymer and the specific compound a, the synergistic effect described above, and the like.

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-receptivity.

Further, it is considered that a lithographic printing plate precursor 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 result that, by containing a specific binder polymer, the non-image portion is easily removed by adhering to the ink roller at the time of on-press development (ink tack development), the above-described synergistic effect, and the like.

The lithographic printing plate precursor according to the present invention is considered to be excellent in all of the requirements including the specific binder polymer, the specific compound a, and the overcoat layer, and is excellent in the inhibition of development residue during on-press development, the ink-applying property, and the on-press developability. It is considered that, if any of the above requirements is absent, at least one of these effects is reduced.

In the field of on-press development type lithographic printing plate precursors, it is known to form an overcoat layer on an image recording layer in order to improve the resistance to brushing and the like. As the overcoat layer, for example, a layer containing a water-soluble polymer is known, but in a lithographic printing plate precursor provided with such an overcoat layer, the ink adhesion of the ink in the obtained lithographic printing plate may be lowered. Therefore, it is known to improve the ink-receiving property by using a sensitizer in the image recording layer. However, when a sensitizer is used for the image recording layer, the on-press developability may be reduced, and the lithographic printing plate precursor according to the present invention is considered to be very useful in terms of achieving both of these properties.

Hereinafter, the details of each constituent element of the lithographic printing plate precursor according to the present invention will be described.

< support >

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 by 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 by 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 necessary, and the pore enlargement treatment and pore sealing treatment of the anodic oxide film as described in japanese patent laid-open No. 2001-253181 and 2001-322365 are appropriately selected and carried out.

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

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

The image-recording layer used in the present invention contains the specific compound a.

In the present invention, the SP value of the specific compound a is less than 18.0. The SP value is preferably 14 to less than 18, more preferably 15 to 17, and still more preferably 16 to 16.9.

SP value (solubility parameter, unit: (MPa)) in the present invention^1/2) Hansen (Hansen) solubility parameters were used.

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

δ(MPa)^1/2＝(δd²+δp²+δh²)^1/2

The dispersion term δ d, the polar term δ p, and the hydrogen bond term δ h are found in Hansen and its successors in large quantities, and are described in detail in Polymer Handbook (four edition), VII-698-711.

In the present invention, the SP value of the Polymer is calculated by the Hoy method described in the Polymer Handbook four edition based on the molecular structure of the Polymer.

Sensitizers

The specific compound a is not particularly limited as long as the SP value is within the above range, and is preferably a sensitizer from the viewpoint of improving the ink adhesion.

The specific compound a may have a molecular weight (weight average molecular weight when having a molecular weight distribution) of 2,000 or more, or may have a molecular weight of less than 2,000.

Examples of the specific compound a include an onium compound, a nitrogen-containing low molecular weight compound, and an ammonium compound such as an ammonium group-containing polymer.

In particular, when the overcoat layer contains an inorganic layered compound, these specific compounds a can function as a surface coating agent for the inorganic layered compound, and can suppress a decrease in the ink adhesion during printing due to the inorganic layered compound.

Onium compounds

From the viewpoint of the ink-absorbing property, the specific compound a is preferably an onium compound.

The onium compound includes a phosphonium compound, an ammonium compound, a sulfonium compound, and the like, and from the above viewpoint, the onium compound is preferably at least one selected from the group consisting of a phosphonium compound and an ammonium compound.

The onium compound in the later-described development accelerator or electron-accepting polymerization initiator is a compound having an SP value exceeding 18, and is not contained in the specific compound a.

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 1, 4-bis (triphenylphosphine) butane bis (hexafluorophosphate), 1, 7-bis (triphenylphosphine) heptane sulfate, and 1, 9-bis (triphenylphosphine) nonane naphthalene-2, 7-disulfonate.

Ammonium compounds

The ammonium compound is preferably a nitrogen-containing low-molecular-weight compound, an ammonium group-containing polymer, or the like.

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, the compounds described in paragraphs 0021 to 0037 of jp 2008-a 284858 and the compounds described in paragraphs 0030 to 0057 of jp 2009-a 090645.

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 80 mol% 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 salt-containing polymer determined by the measurement method described in Japanese patent laid-open No. 2009-208458 is preferably in the range of 5 to 120, more preferably in the range of 10 to 110, and particularly preferably in the range of 15 to 100. 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 copolymer p-toluenesulfonate/3, 6-dioxaheptyl methacrylate (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 copolymer p-toluenesulfonate/hexyl methacrylate (molar ratio 30/70, Mw4.5 ten thousand)

(4)2- (trimethylammonium) ethylmethacrylate hexafluorophosphate/2-ethylhexyl methacrylate copolymer (molar ratio 20/80, Mw6.0 ten thousand)

(5)2- (trimethylammonium) ethylmethacrylate copolymer methyl sulfate/hexyl methacrylate (molar ratio 40/60, Mw7.0 ten thousand)

(6)2- (Butyldimethylammonium) ethyl methacrylate hexafluorophosphate/3, 6-dioxaheptyl methacrylate copolymer (molar ratio 25/75, Mw6.5 ten thousand)

(7)2- (Butyldimethylammonium) ethylacrylate hexafluorophosphate/3, 6-dioxaheptyl methacrylate copolymer (molar ratio 20/80, Mw6.5 ten thousand)

(8)2- (Butyldimethylammonium) 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 20.0% by mass, based on the total mass of the image recording layer.

Simultaneous use

The image recording layer may contain one specific compound a alone, or two or more kinds 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 the specific compound a.

Specifically, from the viewpoint of compatibility between on-press developability and ink-applying property, the image recording layer used in the present invention preferably uses a phosphonium compound, a nitrogen-containing low-molecular-weight compound, and an ammonium group-containing polymer as the specific compound a, and more preferably uses a phosphonium compound, a quaternary ammonium salt, and an ammonium group-containing polymer.

[ development accelerator ]

The image recording layer used in the present invention may contain a development accelerator.

The development accelerator is preferably a hydrophilic high molecular compound or a hydrophilic low molecular compound.

In the present invention, the hydrophilic high molecular compound means a compound having a molecular weight (weight average molecular weight in the case of having a molecular weight distribution) of 3,000 or more, and the hydrophilic low molecular compound means a compound having a molecular weight (weight average molecular weight in the case of having a molecular weight distribution) of less than 3,000.

Hydrophilic polymer compounds

Examples of the hydrophilic polymer compound include a cellulose compound, polyvinyl alcohol, and polyethylene glycol, 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 member 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 member selected from the group consisting of alkyl groups and hydroxyalkyl groups is preferably 1 to 3, more preferably 1.5 to 2.

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 mentioned.

Preferred examples of the hydroxyalkyl cellulose compound include hydroxypropyl cellulose.

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

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, and tris (2-hydroxyethyl) isocyanurate.

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

Examples of the organic sulfonic acid compound include alkyl sulfonic acid, toluene sulfonic acid, benzene sulfonic acid, and salts thereof.

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, and more preferably 100 to 1,000.

Content-

The content of the 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, relative 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 3]

In the formula A1, R^A1、R^A2And R^A2'Each independently represents a hydrogen atom or an alkyl group, Ar represents an aromatic ring group, R^A3Represents a substituent, and n represents an integer not more than the maximum number of substituents of Ar.

In the formula A1, R^A1、R^A2And R^A2'Each independently preferably represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, more preferably a hydrogen atom or a methyl group, and even more preferably a hydrogen atom.

In formula a1, Ar is preferably a benzene ring or a naphthalene ring, more preferably a benzene ring.

In the formula A1, R^A3Preferably an alkyl group or an alkoxy group, more preferably an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, and still more preferably a methyl group or a methoxy group.

In the formula A1, in the presence of a plurality of R^A3In the case of (2), a plurality of R^A3May be the same or different.

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

The content of the structural unit formed from an aromatic vinyl compound in the specific binder polymer is preferably 20 to 70% by mass, and more preferably 30 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 4]

In the formula B1, R^B1Represents a hydrogen atom or an alkyl group.

In the formula B1, R^B1Preferably 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.

The content of the structural unit composed of an acrylonitrile compound in the specific binder polymer is preferably 20 to 70% by mass, and more preferably 30 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 a structural unit formed of an N-vinyl heterocyclic compound, a structural unit represented by the following formula C1 can be preferably mentioned.

[ chemical formula 5]

In the formula C1, Ar^NRepresents a heterocyclic structure containing a nitrogen atom, Ar^NThe nitrogen atom in (b) is bonded to the carbon atom represented by.

In the formula C1, from Ar^NThe 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^NThe 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 5 to 40% by mass, and more preferably 10 to 30% by mass, with respect to 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 a 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 a monomer containing a partial structure represented by the following formula d1 or the following formula d2, for example. 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 6]

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

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

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

In the formulae d1 and d2, X^dpreferably-O-. At X^drepresents-NR^NIn the case of-R^NPreferably 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 7]

In the formula D1, L^D1Represents a single bond or a divalent linking group, L^D2Represents a m +1 valent linking group, X^D1And X^D2Each independently represents-O-or-NR^N-，R^NRepresents a hydrogen atom or an alkyl group, R^D1And R^D2Each independently represents a hydrogen atom or a methyl group, and m represents an integer of 1 or more.

In the formula D1, L^D1Preferably a single bond. At L^D1When the linking group is a divalent group, the linking group 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^D2Preferably, the group is represented by any one of the following formulae D2 to D6.

In the formula D1, X^D1And X^D2Are preferably-O-. And, in X^D1And X^D2At least one of (A) represents-NR^NIn the case of-R^NPreferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and more preferably a hydrogen atom.

In the formula D1, R^D1Preferably methyl.

In the formula D1, m are R^D2At 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 still more preferably 1.

[ chemical formula 8]

In the formulae D2 to D6, L^D3～L^D7Represents a divalent linking group, L^D5And L^D6May be different from X in the formula D1^D1The wavy line portion represents a bonding site with X in the formula D1^D2The bonding site of (3).

In the formula D3, L^D3Preferably an alkylene group, an arylene group or a group in which 2 or more of these are bonded, 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 D4, L^D4Preferably an alkylene group, an arylene group or a group in which 2 or more of these are bonded, 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^D5Preferably an alkylene group, an arylene group or a group in which 2 or more of these are bonded, 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^D6Preferably an alkylene group, an arylene group or a group in which 2 or more of these are bonded, 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 D6, L^D7Preferably an alkylene group, an arylene group or a group in which 2 or more of these are bonded, 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.

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 9]

The content of the structural unit having an ethylenically unsaturated group in the specific binder polymer is preferably 10 to 70% by mass, and more preferably 20 to 50% 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 40% by mass or less, more preferably 35% by mass or less, and still more preferably 30% 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 200mgKOH/g or less, more preferably 180mgKOH/g or less, and still more preferably 150mgKOH/g or less. The lower limit of the acid value is not particularly limited, and may be 0 mgKOH/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 number of carbon atoms of the alkyl group in the arylalkyl (meth) acrylate compound is preferably 1 to 10. 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.

Other structural units-

Certain binder polymers may also contain other structural units. The other constituent unit may include, but is not particularly limited to, a constituent unit other than the above-described constituent units, and examples thereof include a constituent unit formed from an acrylamide compound, a vinyl ether compound, 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, t-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, n-butyl vinyl ether, 2-ethylhexyl vinyl ether, 2-dicyclopen, 4-hydroxymethylcyclohexylmethyl vinyl ether, diethylene glycol monovinyl ether, polyethylene glycol monovinyl ether, chloroethyl monovinyl ether, chlorobutyl vinylether, chloroethoxyethyl vinylether, phenethyl vinylether, phenoxypolyethylene glycol monovinyl ether and the like.

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 10]

[ chemical formula 11]

In the above specific examples, for example, the expression "40/30/10/20" in P1-4 denotes the content ratios (mass ratios) 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.

In the specific examples, the content ratio of each constituent unit can be appropriately changed according to 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 70% 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 may contain 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. Specifically, sodium arylsulfinate and the like can be given.

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 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)₄And the like. Bu 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 12]

The electron-donating polymerization initiator may be added 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. Further, 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 also 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 laid-open Nos. 2006-508380, 2002-287344, 2008-256850, 2001-342222, 9-179296, 9-179297, 9-179298, 2004-294935, 2006-243493, 2002-275129, 2003-064130, 2003-280187, and 10-333321.

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 ester 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- (methacryloyloxyethoxy) 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.

CH₂＝C(R^M4)COOCH₂CH(R^M5)OH (M)

In the formula (M), R^M4And R^M5Each independently represents a hydrogen atom or a methyl group.

Also, urethane acrylates described in Japanese patent laid-open Nos. 51-037193, 2-032293, 2-016765, 2003-344997 and 2006-065210, Japanese patent laid-open Nos. 58-049860, 56-017654 and 62-039417 are preferable, urethane compounds having an ethylene oxide skeleton as described in Japanese patent publication No. 62-039418, Japanese patent application No. 2000-250211 and Japanese patent application No. 2007-094138, and urethane compounds having a hydrophilic group as described in U.S. Pat. No. 7153632, Japanese patent application No. 8-505958, Japanese patent application No. 2007-293221 and Japanese patent application No. 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 may contain an electron accepting 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 accepting 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) The organic halide is preferably a compound described in paragraphs 0022 to 0023 of Japanese patent application laid-open No. 2008-195018, for example.

(b) The carbonyl compound is preferably a compound described in paragraph 0024 of Japanese patent laid-open No. 2008-195018, for example.

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

(d) The organic peroxide is preferably a compound described in paragraph 0025 of Japanese patent laid-open No. 2008-195018, for example.

(e) The metallocene compound is preferably a compound described in paragraph 0026 of Japanese patent laid-open No. 2008-195018, for example.

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

(g) The hexaarylbiimidazole compound is preferably a compound described in paragraph 0027 of Japanese patent laid-open No. 2008-195018, for example.

(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 Japanese patent application laid-open No. 2008-195018, 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-perfluorobutanesulfonate, 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 13]

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. Further, more preferably, an iodonium borate compound in which a salt is formed from an iodonium cation (for example, a di-to-tri-iodonium cation) in the iodonium salt compound described later and a borate anion in the electron donating polymerization initiator is mentioned.

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, aromatic acid dyes, pyrylium salts, metal thiolate complexes, and the like.

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 compounds described in paragraphs 0034 to 0041 of Japanese patent application laid-open No. 2002-278057, paragraphs 0080 to 0086 of Japanese patent application laid-open No. 2008-195018, more preferably compounds described 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, 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 can also be preferably used.

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 absorber absorbing and decomposing infrared light by infrared light exposure is also referred to as a "color-developing body of the decomposable infrared absorber".

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 ray absorber may be any decomposable infrared ray absorber which absorbs and decomposes at least a part of light in the infrared ray wavelength region (wavelength of 750nm to 1mm), and is preferably an infrared ray absorber having a maximum absorption in the wavelength region of 750nm to 1,400 nm.

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 an electron excited from a HOMO (highest occupied orbital) to a LUMO (lowest unoccupied molecular orbital) of a decomposable infrared absorber by exposure to infrared light is transferred intramolecularly 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 14]

The cyanine dye represented by formula 1, when exposed to infrared light, R represents¹-L is a bond cleavage, L being ═ O, ═ S or ═ NR¹⁰Thereby forming a color developing body of the decomposable infrared ray absorbing agent. R¹Disassociate to form free radicals or ions. These contribute to polymerization of the compound having polymerizability contained in the image recording layer.

In formula 1, R₁₁～R₁₈Each 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 1₁₁～R₁₄Each independently is preferably a hydrogen atom or a hydrocarbon group, more preferably a hydrogen atom or an alkaneThe radical is more preferably a hydrogen atom.

And R bonded to a carbon atom bonded to L₁₁And R₁₃Preferably 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 A₁ ⁺R bound to the carbon atom to which it is bound₁₂And A₂R bound to the carbon atom to which it is bound₁₄Preferably each of R₁₅And R₁₇Joined to form a ring.

R in formula 1₁₅Preferably a hydrocarbon group. And, preferably R₁₅And A₁ ⁺R bound to the carbon atom to which it is bound₁₂Joined 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 more preferably an indole ring from the viewpoint of color developability.

R in formula 1₁₇Preferably a hydrocarbon group. And, preferably R₁₇And A₂R bound to the carbon atom to which it is bound₁₄Joined 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 1₁₅And R₁₇The same groups are preferred, and in the case where the groups form respective rings, the same rings are preferably formed.

R in formula 1₁₆And R₁₈Preferably the same groups.

Furthermore, from the viewpoint of improving the water solubility of the compound represented by formula 1, R₁₆And R₁₈Each 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 1¹A cation which can be contained in-L or A₁ ⁺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 1¹A cation which can be contained in-L or A₁ ⁺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 plate₁₆And R₁₈Each 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 an alkyl group having an aromatic ring at the end, and more preferably a 2-phenylethyl group, a 2-naphthylethyl group or a 2- (9-anthryl) ethyl group.

N in formula 1₁₁And n₁₂The 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 1₁And A₂Each independently represents an oxygen atom, a sulfur atom or a nitrogen atom, preferably a nitrogen atom.

A in formula 1₁And A₂Preferably 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 cationic species is represented, examples thereof include alkali metal ions, alkaline earth metal ions, ammonium ions, pyridinium ions, sulfonium ions, and the like, and sodium ions, potassium ions, ammonium ions, pyridinium ions, or sulfonium ions are preferable, and sodium ions, potassium ions, or ammonium ions are more preferable.

R₁₁～R₁₈And R¹L may have an anionic structure and a cationic structure, if R₁₁～R₁₈And R¹L all being charge-neutral radicals, then Za is a monovalent counter anion, e.g. at R₁₁～R₁₈And R¹When L has an anionic structure of 2 or more, Za can be a counter cation.

If the cyanine dye represented by formula 1 has a structure in which the charge is neutral in the entire compound, Za does not exist.

By R in formula 1¹R is an infrared ray exposure¹The group in which the-L bond is cleaved will be described in detail later.

The above-mentioned 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 15]

In the formula 1-A, R¹Represents R by infrared ray exposure¹-L bond-breaking group, R²And R³Each independently represents a hydrogen atom or an alkyl group, R²And R³May be linked to each other to form a ring, Ar¹And Ar²Each independently represents a group forming a benzene ring or a naphthalene ring, Y¹And Y²Each independently represents an oxygen atom, a sulfur atom, -NR⁰Or a dialkylmethylene group, R⁰Represents a hydrogen atom, an alkyl group or an aryl group, R⁴And R⁵Each independently represents an alkyl group, -CO₂M radical or-PO₃M₂M represents a hydrogen atom, a Na atom, a K atom or an onium group, R⁶～R⁹Each independently represents a hydrogen atom or an alkyl group, L represents an oxygen atom, a sulfur atom or-NR¹⁰-，R¹⁰Represents 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，R²～R⁹And R⁰The 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.

R⁰The aryl group in (1) 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 aryl groups, preferred is a phenyl group, a p-methoxyphenyl group, a p-dimethylaminophenyl group, or a naphthyl group.

R²And R³Preferably joined to form a ring.

At R²And R³When they are linked to form a ring, they are preferably 5-or 6-membered rings, and particularly preferably 5-membered rings.

Y¹And Y²Each independently represents an oxygen atom, a sulfur atom, -NR⁰-or dialkylmethylene, preferably-NR⁰-or a dialkylmethylene group, more preferably a dialkylmethylene group.

R⁰Represents a hydrogen atom, an alkyl group or an aryl group, preferably an alkyl group.

R⁴Or R⁵The alkyl groups represented may be substituted alkyl groups. As R⁴Or R⁵Examples of the substituted alkyl group include those represented by any one of the following formulae (a1) to (a 4).

[ chemical formula 16]

-R^W2-CO₂M (a2)

-R^W3-PO₃M₂ (a3)

-R^W4-SO₃M (a4)

In the formulae (a1) to (a4), R^W0Represents an alkylene group having 2 to 6 carbon atoms, W represents a single bond or an oxygen atom, n_W1Represents an integer of 1 to 45, R^W1Represents an alkyl group having 1 to 12 carbon atoms or-C (═ O) -R^W5，R^W5Represents an alkyl group having 1 to 12 carbon atoms, R^W2～R^W4Each 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 (a1), R is^W0Specific 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_W1Preferably 1 to 10, more preferably 1 to 5, particularly preferablyPreferably 1 to 3.

As R^W1Specific 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.

R^W5Alkyl group represented by the formula and R^W1The alkyl radicals are preferably identical to R^W1The preferred modes of the alkyl groups represented are the same.

Specific examples of the group represented by the formula (a1) 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 17]

In the formulae (a2) to (a4), R is^W2～R^W4Specific 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 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 (a3), M which is present in 2 may be the same or different.

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

Among the groups represented by the formulae (a1) to (a4), the group represented by the formula (a1) or the formula (a4) is preferable.

In the formula 1-A, R⁴And R⁵Each is preferably an unsubstituted alkyl group. R⁴And R⁵Preferably the same group.

R⁶～R⁹Each independently represents a hydrogen atom or an alkyl group, preferably a hydrogen atom.

Ar¹And Ar²Each 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 Ar 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 brush resistance of a lithographic printing plate¹And Ar²Each 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 group forming a naphthalene ring or a benzene ring having an alkoxy group as a substituent, and particularly preferably a group forming a naphthalene ring or a benzene ring having a methoxy group as a substituent.

In formula 1-A, Ar¹Or Ar²Preferred is a group forming a group represented by the following formula (b 1).

[ chemical formula 18]

In the formula (b1), R¹⁹Represents an alkyl group having 1 to 12 carbon atoms. n3 represents an integer of 1 to 4. Denotes 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.

R¹～R⁹、R⁰、Ar¹、Ar²、Y¹And Y²Can have an anionic structure and a cationic structure, if R¹～R⁹、R⁰、Ar¹、Ar²、Y¹And Y²All being charge-neutral radicals, then Za is a monovalent counter anion, e.g. at R¹～R⁹、R⁰、Ar¹、Ar²、Y¹And Y²When the anion structure has 2 or more anions, Za can be a counter cation.

By R in the above formula 1 and formula 1-A¹R is an infrared ray exposure¹The group in which the bond of-L is broken will be described later.

In the formula 1 or formula 1-A in which L is an oxygen atom, R is an oxygen atom in view of color development¹The 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 19]

In the formulae (1-1) to (1-7), ● represents a bonding site to the oxygen atom represented by L in the formula 1 or the formula 1-A, and R represents²⁰Each independently represents a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, -OR²⁴、-NR²⁵R²⁶or-SR²⁷，R²¹Each independently represents a hydrogen atom, an alkyl group or an aryl group, R²²Represents aryl, -OR²⁴、-NR²⁵R²⁶、-SR²⁷、-C(＝O)R²⁸、-OC(＝O)R²⁸Or a halogen atom, R²³Represents an aryl group,Alkenyl, alkoxy or onium radicals, R²⁴～R²⁷Each independently represents a hydrogen atom, an alkyl group or an aryl group, R²⁸Represents alkyl, aryl, -OR²⁴、-NR²⁵R²⁶or-SR²⁷，Z¹Represents a counter ion for neutralizing a charge.

At R²⁰、R²¹And R²⁴～R²⁸Preferred modes for the case of alkyl radicals with R²～R⁹And R⁰The preferable mode of the alkyl group in (1) is the same.

R²⁰And R²³The number of carbon atoms of the alkenyl group in (1) to (30) is preferably 1 to (15), more preferably 1 to (10).

At R²⁰～R²⁸Preferred modes for the aryl radical with R⁰The preferred mode of aryl in (1) is the same.

R in the formula (1-1) from the viewpoint of color rendering properties²⁰Preferably alkyl, alkenyl, aryl, -OR²⁴、-NR²⁵R²⁶or-SR²⁷More preferably alkyl, -OR²⁴、-NR²⁵R²⁶or-SR²⁷Further, it is preferably alkyl OR-OR²⁴Particularly preferably-OR²⁴。

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

R in the formula (1-1)²⁰is-OR²⁴In the case of (1), R²⁴The alkyl group is preferably an alkyl group, more preferably an alkyl group having 1 to 8 carbon atoms, still more preferably an isopropyl group or a tert-butyl group, and particularly preferably a tert-butyl group.

R in the formula (1-1)²⁰In 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 properties²¹Preferably a hydrogen atom.

R in the formula (1-2) is a group represented by the formula²²preferably-C (═ O) OR²⁴、-OC(＝O)OR²⁴OR a halogen atom, more preferably-C (═ O) OR²⁴OR-OC (═ O) OR²⁴. R in the formula (1-2)²²is-C (═ O) OR²⁴OR-OC (═ O) OR²⁴In the case of (1), R²⁴Preferably an alkyl group.

R in the formula (1-3) from the viewpoint of color rendering properties²¹Each independently preferably a hydrogen atom or an alkyl group, and at least one R in the formula (1-3)²¹More preferably an alkyl group.

And, R²¹The alkyl group in (1) is preferably an alkyl group having 1 to 10 carbon atoms, and more preferably an alkyl group having 3 to 10 carbon atoms.

And, R²¹The 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, R²¹The alkyl group in (1) is preferably a secondary alkyl group or a tertiary alkyl group.

R in the formula (1-3) is a group represented by the formula²³It 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 R²³Examples 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, and a group obtained by combining these groups.

Among them, a pyridinium group is preferable, 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, particularly preferred is 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, and most preferred is an N-octyl-3-pyridinium group or an N-octyl-4-pyridinium group.

And, in R²³In the case of a pyridinium group, examples of the counter anion include a sulfonate ion, a carboxylate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, a p-toluenesulfonate ion, a perchlorate ion, and 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 properties²⁰Preferably an alkyl or aryl group, more preferably 2R²⁰One of which is an alkyl group and the other is an aryl group. The above 2R²⁰May be joined to form a ring.

R in the formula (1-5) from the viewpoint of color rendering properties²⁰Preferably an alkyl group or 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 properties²⁰Each 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 properties¹As long as it is a counter ion for neutralizing a charge, it may be contained in the Za as a whole.

Z¹Preferably 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 developability¹Is a group represented by the following formula (5).

[ chemical formula 20]

In the formula (5), R¹⁵And R¹⁶Each 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.

R¹⁵Or R¹⁶Alkyl group represented by the formula and R²～R⁹And R⁰The alkyl in (1) is the same as R in a preferred manner²～R⁹And R⁰The preferable mode of the alkyl group in (1) is the same.

R¹⁵Or R¹⁶Aryl and R⁰The aryl in (A) is the same as R in a preferred embodiment⁰The preferred mode of aryl in (1) is the same.

Onium group represented by E and R²³In the same manner as the onium group in (1), preferably in the same manner as R²³The 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 21]

In the formula (6), R¹⁷Represents a halogen atom, an alkyl group, an aryl group, a hydroxyl group or an alkoxy group, in the presence of a plurality of R¹⁷In the case of (2), a plurality of R¹⁷May be the same or different, or a plurality of R¹⁷May be joined to form a ring. n2 represents an integer of 0 to 4. R¹⁸Represents an alkyl group or an aryl group. Z_bRepresents a counter ion for neutralizing a charge.

R¹⁷Or R¹⁸Alkyl or aryl of formula (I) with R²～R⁹And R⁰Alkyl or R in (1)⁰The aryl in (A) is the same as R in a preferred embodiment²～R⁹And R⁰Alkyl or R in (1)⁰The preferred mode of aryl in (1) is the same.

R¹⁷The 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, and an isopropoxy groupN-butoxy group, i-butoxy group, t-butoxy group and the like.

n2 is preferably 0.

Z_bThe counter ion for neutralizing charge represented by the formula (1-7) and Z¹In the same manner, the preferable mode is also the same as Z in the formula (1-7)¹The 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 exemplified¹Specific 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, and ● represents a bonding site to the oxygen atom represented by L in formula 1 or formula 1-A.

[ chemical formula 22]

[ chemical formula 23]

[ chemical formula 24]

[ chemical formula 25]

[ chemical formula 26]

[ chemical formula 27]

[ chemical formula 28]

[ chemical formula 29]

[ chemical formula 30]

In the case where L is an oxygen atom, if R¹Is aryl or linear alkyl, does not cause R upon infrared exposure¹-cleavage of the O bond.

In the case where L in formula 1 or formula 1-A is a sulfur atom, R¹A group represented by the following formula (2-1) is preferred.

[ chemical formula 31]

In the formula (2-1), ● represents a bonding site to the sulfur atom represented by L in the formula 1 or the formula 1-A, and R represents²¹Each independently represents a hydrogen atom, an alkyl group or an aryl group, R²²Represents an aryl, alkenyl, alkoxy or onium group.

L is-NR in formula 1 or formula 1-A¹⁰In the case of-R bonded to N¹A group represented by the following formula (3-1) is preferred.

[ chemical formula 32]

In the formula (3-1), ● represents a bond with the nitrogen atom contained in L in the formula 1 or the formula 1-AThe commissure site, X¹And X²Each 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 R²¹And R²²As 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 like¹⁰-and R¹⁰Represents a hydrogen atom, an alkyl group or an aryl group.

R in the above formula 1 and formula 1-A₁The 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-an O bond breaking group.

[ chemical formula 33]

In the formula 2, R^ZRepresents 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^ZAlkyl group represented by the formula, with the above R²～R⁹And R⁰The 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 is preferably a tertiary alkyl group.

In addition, from the viewpoint 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, ● represents a bonding site with L in formula 1 or formula 1-A.

[ chemical formula 34]

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

[ chemical formula 35]

[ chemical formula 36]

[ chemical formula 37]

Further, as the infrared absorber decomposed by the infrared exposure, the infrared absorbers described in Japanese patent application laid-open 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, 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 of No. 1/1992 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 an acrylate or methacrylate having a polyalkylene structure, and mixtures thereof. Preferably, the resin composition includes a copolymer of polystyrene, styrene and acrylonitrile, or 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 capable of undergoing any reaction, and is preferably a polymerizable group, and examples thereof include an ethylenically unsaturated group (for example, acryloyl group, methacryloyl group, vinyl group, allyl group, etc.) which undergoes a radical polymerization reaction, a cationically polymerizable group (for example, vinyl group, vinyloxy group, epoxy group, oxetanyl group, etc.), an isocyanate group or a block thereof which undergoes an addition reaction, an epoxy group, a vinyloxy group, a functional group having an active hydrogen atom to be a target of these reactions (for example, amino group, hydroxyl group, carboxyl group, etc.), a carboxyl group which undergoes a condensation reaction, a hydroxyl group or an amino group to be a target of the reactions, an acid anhydride which undergoes a ring-opening addition reaction, an amino group or a hydroxyl group to be a target of the reactions, 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 used. 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 a 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 polymer particles described in paragraphs 0032 to 0095 of Japanese patent laid-open No. 2012-206495.

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 side group include- [ CH ]₂CH(C≡N)-]Or- [ CH ]₂C(CH₃)(C≡N)-]。

Further, the constituent unit having the cyano side 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.

The particles of the resin having a hydrophobic main chain and containing i) a constitutional unit having a cyano side group directly bonded to the hydrophobic main chain and ii) a constitutional unit having a side group containing a hydrophilic polyalkylene oxide segment preferably include particles of the resin described in paragraphs 0039 to 0068 of Japanese patent application laid-open No. 2008-503365.

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 over 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 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.

Examples of such an acid color developer 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, 3-bis (1, 2-dimethylindol-3-yl) -5-dimethylaminophthalide, and, 3, 3-bis (1, 2-dimethylindol-3-yl) -6-dimethylaminobenzthalide, 3-bis (9-ethylcarbazol-3-yl) -6-dimethylaminobenzthalide, 3-bis (2-phenylindol-3-yl) -6-dimethylaminobenzthalide, 3- (4-dimethylaminophenyl) -3- (1-methylpyrrol-3-yl) -6-dimethylaminobenzthalide, 3-bis [ 1, 1-bis (4-dimethylaminophenyl) ethen-2-yl ] -4,5,6, 7-tetrachlorophthalide, 3-bis [ 1, 1-bis (4-pyrrolidinophenyl) ethen-2-yl ] -4,5,6, 7-Tetrabromophenylphthalide, 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- Phthalides such as N-ethyl-N-phenylaminophenyl) phthalide, 3- (2-ethoxy-4-diethylaminophenyl) -3- (1-N-octyl-2-methylindol-3-yl) phthalide, 3-bis (1-N-octyl-2-methylindol-3-yl) phthalide, 3- (2-methyl-4-diethylaminophenyl) -3- (1-N-octyl-2-methylindol-3-yl) phthalide, 4-bis-dimethylaminobenzopropanol benzyl ether, N-halophenyl-colorless auramine, N-2,4, 5-trichlorophenyl colorless auramine, rhodamine-B-anilinolactam, Rhodamine- (4-nitroanilino) lactam, rhodamine-B- (4-chloroanilino) lactam, 3, 7-bis (diethylamino) -10-benzoylbenzoxazine, benzoyl leuco methylene blue, 4-nitrobenzoylmethylene blue, 3, 6-dimethoxyfluorane, 3-dimethylamino-7-methoxyfluorane, 3-diethylamino-6-methoxyfluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3-diethylamino-6, 7-dimethylfluorane, 3-N-cyclohexyl-N-N-butylamino-7-methylfluorane, 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 ' -dichloroanilino) fluoran, 3-diethylamino-7- (3 ' -trifluoromethylanilino) fluoran, 3-di-n-butylamino-7- (2 ' -fluoroanilino) fluoran, and a salt thereof, 3-di-N-butylamino-7- (2 ' -chlorophenylamino) fluoran, 3-N-isopentyl-N-ethylamino-7- (2 ' -chlorophenylamino) fluoran, 3-N-N-hexyl-N-ethylamino-7- (2 ' -chlorophenylamino) fluoran, 3-diethylamino-6-chloro-7-anilinofluoran, 3-di-N-butylamino-6-chloro-7-anilinofluoran, 3-diethylamino-6-methoxy-7-anilinofluoran, 3-di-N-butylamino-6-ethoxy-7-anilinofluoran, 3-pyrrolidinyl-6-methyl-7-anilinofluoran, 3-diethylamino-6-methoxy-7-anilinofluoran, 3-di-N-butylamino-ethylamino-7-anilinofluoran, 3-pyrrolidinyl-6-methyl-, 3-hydropyridyl-6-methyl-7-anilinofluoran, 3-morpholino-6-methyl-7-anilinofluoran, 3-dimethylamino-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-anilinofluoran, 3-di-N-butylamino-6-methyl-7-anilinofluoran, 3-di-N-pentylamino-6-methyl-7-anilinofluoran, 3-N-ethyl-N-methylamino-6-methyl-7-anilinofluoran, 3-N-N-propyl-N-methylamino-6-methyl-7-anilinofluoran, 3-morpholino, 3-methyl-7-anilinofluoran, 3-N-methyl, 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-hexyl-N-methylamino-6-methyl-7-anilinofluoran, 3-N-cyclohexyl-N-ethylamino-6-methyl-7-anilinofluoran, 3-N-cyclohexyl-N-N-propylamino-6-methyl-7-anilinofluoran, 3-N-cyclohexyl-N-N-butylamino-6-methyl-7-anilinofluoran, 3-N-cyclohexyl-N-N-hexylamino-6-methyl-7-anilinofluoran, 3-N-cyclohexyl-N-N-octylamino-6-methyl-7-anilinofluoran, 3-N-cyclohexyl-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-methylamino-6-methyl-7-anilinofluoran, 3-N- (3 ' -ethoxypropyl) -N-ethylamino-6-methyl-7-anilinofluoran, 3-N- (2 ' -tetrahydrofurfuryl) -N-ethylamino-6-methyl-7-anilinofluoran, 3-N- (4 ' -tolyl) -N-ethylamino-6-methyl-7-anilinofluoran, 3-diethylamino-6-ethyl-7-anilinofluoran, 3-diethylamino-6-methyl-7- (3 ' -toluylamino) fluoran, 3-diethylamino-6-methyl-7- (2 ', 6 ' -ditoluylamino) fluoran, 3-di-N-butylamino-7- (2 ', 6 ' -ditoluylamino) fluoran, 2-bis [ 4 ' - (3-N-cyclohexyl-N-methylamino-6-methylfluoran ] Fluoranes such as (E) -7-ylaminophenyl) propane, (E) -3- [ 4 '- (4-phenylaminophenyl) aminophenyl ] amino-6-methyl-7-chlorofluorane, (E) -3- [ 4' - (dimethylaminophenyl) ] amino-5, 7-difluorane, (E) -3- (2-methyl-4-diethylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide, (E) -3- (2-n-propoxycarbonylamino-4-di-n-propylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide, and (E) -3- (2-methylamino-4-di-n-propylaminophenyl) -3- (1-methyl-4-aminophthalide -ethyl-2-methylindol-3-yl) -4-azaphthalide, 3- (2-methyl-4-di-n-hexylaminophenyl) -3- (1-n-octyl-2-methylindol-3-yl) -4, 7-diazophthalide, 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, a salt thereof, a hydrate thereof, 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 -azaphthalide, 3- (2-butoxy-4-diethylaminophenyl) -3- (1-ethyl-2-phenylindol-3-yl) -4 or 7-azaphthalide 3-methyl-spiro-dinaphthopyran, 3-ethyl-spiro-dinaphthopyran, 3-phenyl-spiro-dinaphthopyran, 3-benzyl-spiro-dinaphthopyran, 3-methyl-naphtho- (3-methoxybenzo) spiropyran, 3-propyl-spiro-dibenzopyran-3, 6-bis (dimethylamino) fluorene-9-spiro-3 '- (6' -dimethylamino) phthalide, 3, 6-bis (diethylamino) fluorene-9-spiro-3 '- (6' -dimethylamino) phthalide Phthalides such as phenyl phthalide, and other phthalides, 2 ' -anilino-6 ' - (N-ethyl-N-isoamyl) amino-3 ' -methylspiro [ isobenzofuran-1 (3H), 9 ' - (9H) xanthen-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, 2 ' - (N-methyl-N-phenyl) amino-6 ' - (N N-ethyl-N- (4-tolyl)) aminospiro [ isobenzofuran-1 (3H), 9' - (9H) xanthen ] -3-one, and the like.

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 developed dye 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 (manufactured by Fukui Yamada Chemical Co., Ltd.), ANGE-DCF, Vermilion-DCF, PINK-DCF, RED-DCF, BLBL, CVL, GREEN-DCF, TH-107 (manufactured by HODOGAYA CHEMICAL CO., LTD), ODB-2, ODB-4, ODB-250, ODB-BlackXV, BLUE-63, BLUE-502, GN-2, GN-118, Green-40, and Red Inc. (manufactured by Chemicals, Inc.), and crystal lactone. 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 a film formed therefrom has a good visible light absorption rate.

These acid color developers may be used alone, or two or more components 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 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.

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, the polymer chain having a polymerizable group. As the star polymer compound, for example, the compounds described in Japanese patent laid-open 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 equivalent by GPC.

If necessary, a hydrophilic polymer such as polyacrylic acid or polyvinyl alcohol described in Japanese patent application laid-open No. 2008-195018 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% by mass, and more preferably 5 to 80% by 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 38]

[ chemical formula 39]

[ chemical formula 40]

[ chemical formula 41]

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.

[ 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 description 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-mentioned 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 application²～3.0g/m². 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 thereof 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, ethylene glycol diethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, ethylene glycol monoethyl ether, N, N-dimethylformamide, dimethyl sulfoxide, γ -butyrolactone, methyl lactate, ethyl lactate, and the like. 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 (solid content) applied 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 properties of the image recording layer²～3.0g/m²。

The film thickness of the image recording layer in the lithographic printing plate precursor according to the present invention is preferably 0.8 to 3 μm, and more preferably 1 to 2 μm.

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.

< overcoat layer >

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 scratches from being generated in the image recording layer and the function of preventing ablation upon exposure to high-illuminance laser light.

The overcoating having such characteristics is described in, for example, U.S. Pat. No.3,458,311 and Japanese patent publication No. 55-049729. The low oxygen-permeable polymer used in the overcoat layer may be used by appropriately selecting either one of a water-soluble polymer and a water-insoluble polymer, or may be used by mixing two or more kinds of polymers as necessary.

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 saponification degree described above was measured 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 30 to 100% by mass, more preferably 40 to 100% by mass, and still more preferably 50 to 100% 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.H₂Talc 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: a (B, C)_2-5D₄O₁₀(OH,F,O)₂Wherein 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 KMg₃(AlSi₃O₁₀)F₂Potassium tetrasilicic mica KMg_2.5(Si₄O₁₀)F₂Iso-nonswelling mica and Na-tetrafluoro silicon mica NaMg_2.5(Si₄O₁₀)F₂Na or Li with mica (Na, Li) Mg₂Li(Si₄O₁₀)F₂Montmorillonite series Na or Li hectorite (Na, Li)_1/8Mg_2/5Li_1/8(Si₄O₁₀)F₂And 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⁺、Ca²⁺、Mg²⁺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 bonding between the lamellar lattices is weak because the ionic radius is small, and the swelling is 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 thus it is particularly preferably used.

The shape of the mica compound is preferably as thin as possible from the viewpoint of diffusion control, and the larger the plane size is, the better the smoothness of the coated surface and the transparency of the active light ray are not hindered. 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/m²～10g/m²More preferably 0.02g/m²～3g/m²Particularly preferably 0.02g/m²～1g/m²。

The thickness of the overcoat layer in the lithographic printing plate precursor according to the present invention is preferably 0.8 to 3 μm, and more preferably 1 to 2 μm.

The thickness of the overcoat layer in the lithographic printing plate precursor according to the present invention is preferably 1.1 to 5 times, and more preferably 1.1 to 3 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 the effect of preventing the heat generated by exposure from diffusing to the support and decreasing the sensitivity is also obtained.

Examples of the compound used for the undercoat layer include polymers having adsorptive groups and hydrophilic groups 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 the adsorptive group which can be adsorbed on the surface of the support, preferred are a phenolic hydroxyl group, a carboxyl group and-PO₃H₂、-OPO₃H₂、-CONHSO₂-、-SO₂NHSO₂-and-COCH₂COCH₃. 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 that of 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 preferable to 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, as 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 adsorbable on the surface of a support, as described in jp 2005-125749 a and jp 2006-188038 a.

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

For the base coat, by known methodsThe method is used for coating. The amount of the primer coating (solid content) is preferably 0.1mg/m²～100mg/m²More preferably 1mg/m²～30mg/m²。

(method of 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 image-wise exposing the on-press development type lithographic printing plate precursor according to the present invention (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 according to 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-wise 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 1,400 nm. The light source of 750nm to 1,400nm is preferably a solid-state laser or a semiconductor laser that radiates infrared rays. 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/cm²～300mJ/cm². 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 subjected to image exposure 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 on a printing press to remove an image recording layer of a non-image portion.

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

[ on-machine development method ]

In the on-press development method, the lithographic printing plate precursor subjected to image exposure is preferably subjected to supply of an oil-based ink and an aqueous component on a printing press to remove an image-recording layer in a non-image portion, thereby producing a lithographic printing plate.

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. Thus, the lithographic printing plate precursor is subjected to on-press development on a printing press and is directly used in multi-sheet printing. 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 1,400 nm. 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 developing 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 body 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 48 and comparative examples 1 to 6)

< production of support >

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 used³) The surface of the aluminum plate was granulated and thoroughly washed with water. Aluminum plate is putAfter etching and washing with water by immersing the substrate in a 25 mass% aqueous solution of sodium hydroxide at 45 ℃ for 9 seconds, the substrate was further immersed in a 20 mass% aqueous solution of nitric acid at 60 ℃ for 20 seconds and washed with water. The etching amount of the grained surface was about 3g/m²。

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 ℃. In the ac power waveform, the electrochemical roughening treatment was performed using a trapezoidal rectangular wave ac with a time TP for the current value to reach the peak value from zero of 0.8ms and a duty ratio of 1:1, with the carbon electrode being the counter electrode. Ferrite is used as the auxiliary anode. The current density was 30A/dm at the peak of the current²And 5% of the current from the power supply is shunted to the auxiliary anode. The electric quantity in the nitric acid electrolysis is 175C/dm of that when the aluminum plate is used as the anode². 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 anode²The 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/dm²Form 2.5g/m²The 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 10 nm.

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 to obtain an average value. The standard deviation is ± 10% or less of the mean.

< formation of lithographic printing plate precursor >

A primer coating liquid (1) having the following composition was applied to the support so that the dry coating amount became 20mg/m²And dried at 100 ℃ for 30 seconds by an oven, thereby producing a support having an undercoat layer.

The following image recording layer coating liquid (1) was bar-coated on the undercoat layer, and dried at 100 ℃ for 60 seconds to have a film thickness as described in tables 1 to 4 to form an image recording layer, thereby obtaining a lithographic printing plate precursor.

Then, an overcoat layer coating liquid (1) having the following composition was applied on the image recording layer, and dried at 100 ℃ for 60 seconds to have a film thickness described in tables 1 to 4 to form an overcoat layer, thereby obtaining a lithographic printing plate precursor.

[ undercoating liquid (1) ]

The following undercoating compound 1: 0.18 part

Methanol: 55.24 parts

Distilled water: 6.15 parts

Synthesis of priming Compound 1

Purification of monomer M-1

LIGHT ESTER P-1M (2-methacryloyloxyethyl acid phosphate, KYOEISHA CHEMICAL 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 mixture was heated 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 ] dithioic acid dihydrate (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 then 0.005 part of 4-hydroxy-2, 2,6, 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 42]

Dropping solution 1

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

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 (1) for image recording layer >

Infrared absorbers 1 (compounds of the following structures) described in tables 1 to 4: 0.030 parts of

Di-p-triiodonium PF₆ ^-Salt (manufactured by Aldrich Co.): 0.032 portion

Sensitizers described in tables 1 to 4: amounts shown in tables 1 to 4

Adhesive polymers described in tables 1 to 4: amounts shown in tables 1 to 4

BYK306(Byk Chemie Co.): 0.008 portion

1-methoxy-2-propanol: 8.609 parts

Methyl ethyl ketone: 1.091 parts

[ chemical formula 43]

< overcoat coating liquid >

Water-soluble polymers described in tables 1 to 4: amounts shown in tables 1 to 4

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

Water: the whole amount is 10 parts by mass

(examples 49 and 50)

A lithographic printing plate precursor was obtained in the same manner as in example 1, except that the infrared absorber 1 was changed to the infrared absorber described in table 5 in example 1.

< evaluation >

[ on-machine developability ]

The lithographic printing plate precursor obtained in the above was exposed to light at an outer drum rotation speed of 1,000rpm (emissions per minute), a laser output of 70%, and a resolution of 2,400dpi (1 inch to 2.54cm) using Luxel PLATESETTER T-6000III manufactured by Fujifilm Corporation mounting an infrared semiconductor laser. The exposure image was set to include a solid image, a graph of 20 μm dots of 50% halftone dots frequency-modulated and screened, and a non-image portion.

The obtained exposed original plate was mounted on a plate cylinder of a printer LITHRONE26 manufactured by KOMORI Corporation without being subjected to a development process. After on-line development was performed by supplying fountain solution and ink by a standard automatic print start method of printer LITHRONE26 manufactured by KOMORI Corporation using fountain solution of Ecity-2 (manufactured by Fujifilm Corporation)/tap water (2/98 (volume ratio)) and Space Color fusion G yellow ink (manufactured by DIC Graphics Corporation), 500 sheets were printed on Tokubishi Art (manufactured by Ltd., continuous mass: 76.5kg) Paper at a print speed of 10,000 sheets per hour.

The number of sheets of printing paper required until the unexposed portions of the image recording layer were developed on the printing press on the machine, and the ink was not transferred to the non-image portions was measured as on-machine developability, and is shown in tables 1 to 4. The smaller the number of sheets, the more excellent the on-press developability.

[ development residue inhibitory Property ]

The evaluation of the on-press developability was repeated 3 times using the same lithographic printing plate precursor, and the development residue adhering to the water injection roller in the printing press was transferred to a transparent adhesive tape and adhered to OK top coat PAPER + (OJI PAPER co., ltd., manufactured), and the cyan concentration d (c) was measured by a color density meter X-Rite (manufactured by X-Rite) and is shown in tables 1 to 4. The smaller the value of the cyan density d (c), the more excellent the development residue suppression property.

Evaluation criteria-

Evaluation 5: d (C) less than 0.1

Evaluation 4: d (C) is 0.1 or more and less than 0.3

Evaluation 3: d (C) is 0.3 or more and less than 0.5

Evaluation 2: d (C) is 0.5 or more and less than 1.0

Evaluation 1: d (C) is 1.0 or more

[ inking Property (initial ink inking Property for printing) ]

The lithographic printing plate exposed under the same exposure conditions as those in the evaluation of on-press developability described above (set to a chart containing a solid image and a 50% halftone dot of a 20 μm dot frequency modulated screen in the exposed image) was mounted on a plate cylinder of a printer LITHRONE26 manufactured by KOMORI Corporation. The fountain solution and ink were supplied and printing was started by the standard automatic printing start method of LITHRONE26 using a fountain solution of ecoity-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 (Mitsubishi Oji Paper Sales co., manufactured by ltd., continuous volume: 76.5kg) Paper at a printing speed of 10,000 sheets per hour.

The ink density in the solid image portion was measured using a MACBETH densitometer (ex dark, ex black) and the number of sheets of printing paper required until the ink density became 1.0 or more was measured as an index of ink receptivity (initial ink receptivity in printing), and is shown in tables 1 to 4. It can be said that the smaller the number of sheets, the more excellent the ink adhesion of the lithographic printing plate.

Evaluation criteria-

Evaluation 1: more than 100 sheets

Evaluation 2: 50 or more and less than 100

Evaluation 3: more than 30 and less than 50

Evaluation 4: 20 or more and less than 30

Evaluation 5: less than 20 sheets

[ Brush resistance ]

The lithographic printing plate precursors obtained in example 1, example 49, and example 50 were exposed to light using a Luxel PLATESETTER T-6000III (manufactured by Fujifilm Corporation) equipped with an infrared semiconductor laser under conditions of an outer drum rotation speed of 1,000rpm (fluctuations per minute), a laser output of 70%, and a resolution of 2,400dpi (1 inch to 2.54 cm). A graph of solid images and 20 μm point fm screened 50% dots is included in the exposure image.

The obtained exposed lithographic printing original plate was mounted on a plate cylinder of a printer LITHRONE26 manufactured by KOMORI Corporation without being subjected to a development treatment. After on-press development was performed by supplying fountain solution and ink by the standard automatic printing start method of LITHRONE26 using fountain solution of ecoity-2 (manufactured by Fujifilm Corporation)/tap water of 2/98 (volume ratio) and Space Color fusion g ink (manufactured by DIC Graphics Corporation) on the basis of decelerating the water supply roller by 5% with respect to the plate cylinder, 50,000 sheets were printed on Tokubishi Art (76.5kg) paper at a printing speed of 10,000 sheets per hour.

As the number of printed sheets increases, the image recording layer gradually wears and the ink receptivity decreases, so the ink concentration in the printing paper decreases. The number of printed copies was determined by measuring the dot area ratio of 3% halftone dots in the printed matter by the use of x-lite (manufactured by x-lite corporation) and determining that the value was 5% lower than the measured value of the 100 th printed sheet, and the print durability was evaluated.

[ Table 3]

[ Table 5]

In tables 1 to 5, the numerical values described in "binder polymer 1", "binder polymer 2" in the column of the specific binder polymer and "PVA 105" in the column of the comparative binder polymer represent the contents (parts by mass) of the following "binder polymer 1", "binder polymer 2" and "PVA 105". The expression "-" indicates that the corresponding compound is not contained.

In tables 1 to 5, the values in the columns "sensitizer 1" to "sensitizer 17" of specific compound a and "tetrabutylphosphonium iodide" of the comparative sensitizer represent the contents (parts by mass) of the following "sensitizer 1" to "sensitizer 17" and "tetrabutylphosphonium iodide". The expression "-" indicates that the corresponding compound is not contained.

In tables 1 to 5, "PVA 105", "PVA 405", "PEG 2000" or "PVP" described in the column of the top coat layer indicates the content (parts by mass) of the following "water-soluble polymer".

The details of the compounds shown in tables 1 to 5 are as follows.

< Special adhesive Polymer >

[ Synthesis of adhesive Polymer 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 was added dropwise over 30 minutes a solution of compound 1: 50.0g, Compound 2: 50.0g, AIBN0.7g and 100g of methyl ethyl ketone. 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 a binder polymer 1 (P2-1). The weight average molecular weight of the obtained adhesive polymer 1 was 75,000.

[ chemical formula 44]

[ Synthesis of adhesive Polymer 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 was added dropwise over 30 minutes a solution of compound 1: 50.0g, Compound 2: 30.0g, compound 3: 20.0g, AIBN (azobisisobutyronitrile) 0.7g and methyl ethyl ketone 100 g. 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 a binder polymer 1. The weight average molecular weight of the obtained adhesive polymer 2(P2-2) was 75,000.

[ chemical formula 45]

In tables 1 to 4, the details of "P2-2-1" to "P2-2-8" of the specific binder polymers are as follows.

[ chemical formula 46]

[ comparison with specific Binder polymers ]

PVA 105: polyvinyl alcohol, KURARAY co

< specific sensitizer >

Sensitizer 1:1, 4-bis (triphenylphosphine) butane ═ bis (hexafluorophosphate), SP value: 16.2

Sensitizer 2: 1, 7-bis (triphenylphosphine) heptane ═ sulfate, SP value: 15.6

Sensitizer 3: 1, 9-bis (triphenylphosphine) nonane ═ naphthalene-2, 7-disulfonate, SP value: 15.5

Sensitizer 4: tetramethylammonium-hexafluorophosphate, SP value: 14.5

Sensitizer 5: tetrabutylammonium ═ hexafluorophosphate, SP value: 15.7

Sensitizer 6: dodecyltrimethylammonium ═ p-toluenesulfonic acid, SP value: 15.6

Sensitizer 7: benzyl triethylammonium ═ hexafluorophosphate, SP value: 17.0

Sensitizer 8: benzyldimethyloctylammonium ═ hexafluorophosphate, SP value: 16.8

Sensitizer 9: benzyldimethyldodecylammonium ═ hexafluorophosphate, SP value: 16.5

Sensitizer 10: 2- (trimethylammonium) ethylmethacrylate copolymer p-toluenesulfonic acid/3, 6-dioxaheptyl methacrylate (molar ratio: 10/90, molecular weight (Mw); 4.5 ten thousand), SP value: 17.0

Sensitizer 11: 2- (trimethylammonium) ethyl methacrylate hexafluorophosphate/3, 6-dioxaheptyl methacrylate copolymer (molar ratio: 20/80, molecular weight (Mw); 6.0 ten thousand), SP value: 16.9

Sensitizer 12: 2- (ethyldimethylammonio) ethylmethacrylate (p-toluenesulfonic acid/hexylmethacrylate copolymer (molar ratio: 30/70, molecular weight (Mw); 4.5 ten thousand), SP value: 16.1

Sensitizer 13: 2- (trimethylammonium) ethyl methacrylate copolymer (molar ratio: 20/80, molecular weight (Mw); 6.0 ten thousand), SP value: 16.0

Sensitizer 14: 2- (trimethylammonium) ethyl methacrylate copolymer (molar ratio: 40/60, molecular weight (Mw); 7.0 ten thousand), SP value: 16.2

Sensitizer 15: 2- (butyldimethylammonio) ethyl methacrylate hexafluorophosphate/3, 6-dioxaheptyl methacrylate copolymer (molar ratio: 25/75, molecular weight (Mw); 6.5 ten thousand), SP value: 16.8

Sensitizer 16: 2- (butyldimethylammonio) ethylacrylate hexafluorophosphate/3, 6-dioxaheptyl methacrylate copolymer (molar ratio: 20/80, molecular weight (Mw); 6.5 ten thousand), SP value: 16.9

Sensitizer 17: 2- (butyldimethylammonio) ethylmethacrylate ═ 13-ethyl-5, 8, 11-trioxa-1-heptadecane sulfonate/3, 6-dioxaheptyl methacrylate copolymer (molar ratio: 20/80, molecular weight (Mw); 7.5 ten thousand), SP value: 16.9

< comparative sensitizer >

Tetrabutylphosphonium iodide, SP value: 18.4

< Water-soluble Polymer >

PVA 105: polyvinyl alcohol (degree of saponification 98 mol% to 99 mol%), KURARAY co

PVA 405: polyvinyl alcohol (degree of saponification: 80 mol% to 83 mol%), KURARAY co

PEG 4000: polyethylene glycol, Tokyo Chemical Industry Co., Ltd

PVP K-85: polyvinylpyrrolidone, NIPPON SHOKUBA CO., LTD. preparation

< polymerizable Compound >

A9300: ethoxylated isocyanuric acid triacrylate (Shin-Nakamura Chemical Co., Ltd., manufactured by Ltd.)

DPHA: dipentaerythritol hexaacrylate (Shin-Nakamura Chemical Co., Ltd., manufactured by Ltd.)

[ Infrared absorber ]

The details of the infrared absorbers in table 5 are as follows.

Infrared absorber 2: a compound of the structure

Infrared absorber 3: a compound of the structure

[ chemical formula 47]

From the results shown in tables 1 to 5, it is understood that the lithographic printing plate precursors according to the examples can provide lithographic printing plates having excellent on-press development residue suppression properties and excellent on-press development properties and inking properties.

The disclosures of japanese patent application No. 2018-142429 applied at 30/7/2018 and japanese patent application No. 2018-205749 applied at 31/10/2018 are incorporated herein by reference in their entirety.

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 compound A having an SP value of less than 18.0,

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 exceeds 0 mass% and is 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 any one of claims 1 to 4,

the compound A is a sensitizer.

6. The on-press developable lithographic printing plate precursor according to any one of claims 1 to 5,

the molecular weight of the compound A is more than 2000.

7. The on-press developable lithographic printing plate precursor according to any one of claims 1 to 5,

the molecular weight of the compound A is less than 2000.

8. The on-press developable lithographic printing plate precursor according to any one of claims 1 to 7,

the compound A is an onium compound.

9. The on-press developable lithographic printing plate precursor according to claim 8,

the onium compound includes at least one selected from the group consisting of an ammonium compound and a phosphonium compound.

10. The on-press developable lithographic printing plate precursor according to any one of claims 1 to 9, containing two or more of the compound a.

11. The on-press developable lithographic printing plate precursor according to any one of claims 1 to 10,

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

12. The on-press developable lithographic printing plate precursor according to any one of claims 1 to 11,

the image recording layer further comprises an infrared absorber.

13. The on-press developable lithographic printing plate precursor according to claim 12,

the infrared absorber is decomposed by infrared exposure.

14. The on-press developable lithographic printing plate precursor according to claim 12 or 13,

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

15. The on-press developable lithographic printing plate precursor according to any one of claims 12 to 14,

the infrared absorbent is cyanine pigment.

16. The on-press developable lithographic printing plate precursor according to any one of claims 12 to 15,

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

in the formula 1, R¹Represents R by infrared ray exposure¹-L bond-breaking group, R₁₁～R₁₈Independently represent a hydrogen atom, a halogen atom, -Ra, -ORb, -SRc or-NRdRe, Ra to Re independently represent a hydrocarbon group, A₁、A₂And a plurality of R₁₁～R₁₈Optionally linked to form a monocyclic or polycyclic ring, A₁And A₂Each independently represents an oxygen atom, a sulfur atom or a nitrogen atom, n₁₁And n₁₂Each independently represents an integer of 0 to 5, wherein n₁₁And n₁₂Is 2 or more, n₁₃And n₁₄Each independently represents 0 or 1L represents an oxygen atom, a sulfur atom or-NR¹⁰-，R¹⁰Represents a hydrogen atom, an alkyl group or an aryl group, and Za represents a counter ion for neutralizing a charge.

17. The on-press developable lithographic printing plate precursor according to claim 16,

r in the formula 1¹Is a group represented by the following formula 2,

in the formula 2, R^ZRepresents an alkyl group, and the wavy line moiety represents a bonding site to a group represented by L in the formula 1.

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

a step of image-wise exposing the on-press development type lithographic printing plate precursor of any one of claims 1 to 17; and

19. A lithographic method, comprising:

a step of image-wise exposing the on-press development type lithographic printing plate precursor of any one of claims 1 to 17;

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