WO2020080371A1

WO2020080371A1 - Lithographic printing original plate and lithographic printing plate production method

Info

Publication number: WO2020080371A1
Application number: PCT/JP2019/040523
Authority: WO
Inventors: 尚志佐藤; 加奈栢木
Original assignee: 富士フイルム株式会社
Priority date: 2018-10-17
Filing date: 2019-10-15
Publication date: 2020-04-23

Abstract

This lithographic printing original plate has an image recording layer on a support, wherein the image recording layer contains, an alkali-soluble resin, an infrared ray absorbing agent having a weight average molecular weight not less than 4,000, and onium salt compound. This lithographic printing plate production method uses said lithographic printing original plate.

Description

Lithographic printing plate precursor and method of making lithographic printing plate

The present disclosure relates to a planographic printing plate precursor and a method for producing a planographic printing plate.

Generally, a lithographic printing plate consists of a lipophilic image area that receives ink during the printing process and a hydrophilic non-image area that receives fountain solution.
Lithographic printing utilizes the property that water and oil-based ink repel each other, and the lipophilic image part of the lithographic printing plate is the ink receiving part, and the hydrophilic non-image part is the dampening water receiving part (ink non-receiving part). ) Is a method in which a difference in ink adhesion is caused on the surface of the lithographic printing plate, the ink is applied only to the image area, and then the ink is transferred to a printing medium such as paper for printing.
Currently, in a plate making process for producing a lithographic printing plate from a lithographic printing plate precursor, image exposure is performed by a CTP (computer to plate) technique. That is, image exposure is carried out by using a laser or a laser diode directly on a lithographic printing plate precursor by scanning exposure without using a lith film.
As a conventional lithographic printing plate precursor or a photosensitive resin composition used for its production, for example, those described in Patent Documents 1 to 3 are known.

Patent Document 1 discloses a lithographic printing plate precursor comprising a support and a resin and an infrared absorbing agent, and having at least two or more positive type recording layers whose solubility in an alkaline aqueous solution is increased by infrared laser exposure, on a support, Of the positive recording layers, the positive recording layer closest to the support contains at least two resins, at least one of these resins forms a dispersed phase, and at least one of the above resins is used. A lithographic printing plate precursor characterized in that one is a polymer containing maleimide is described.

In Patent Document 2, an image recording layer containing a ternary to quaternary copolymer having a maleimide structure and an infrared absorber is provided on a support, and the weight average molecular weight of the above copolymer is 15,000 to 35. And a lithographic printing plate precursor having a number average molecular weight of 7,000 to 15,000.

Patent Document 3 contains a novolac-type phenol resin and an infrared absorbing dye, and the infrared absorbing dye is a polymer obtained by a graft reaction between an alkali-soluble resin and a low-molecular infrared absorbing dye. Infrared compositions are described.

Patent Document 1: Japanese Patent Application Laid-Open No. 2006-3658 Patent Document 2: Chinese Patent Application Publication No. 1038716969 Patent Document 3: Chinese Patent Application Publication No. 101770167

The problem to be solved by the embodiments of the present invention is to provide a lithographic printing plate precursor excellent in development latitude and scratch resistance.
A problem to be solved by another embodiment of the present invention is to provide a method for producing a lithographic printing plate using the lithographic printing plate precursor.

Means for solving the above problems include the following aspects.
<1> A lithographic printing plate precursor having an image recording layer on a support, the image recording layer containing an alkali-soluble resin, an infrared absorber having a weight average molecular weight of 4,000 or more, and an onium salt compound.
<2> The lithographic printing plate precursor as described in <1> above, wherein the infrared absorber has an acidic group.
<3> The lithographic printing plate precursor as described in <1> or <2> above, wherein the infrared absorber contains a dye structure that absorbs infrared rays and a polymer structure.
<4> The lithographic printing plate precursor as described in <3>, wherein the polymer structure includes a phenol resin structure.
<5> The lithographic printing plate precursor as described in any one of <1> to <4>, wherein the image recording layer has an upper layer and a lower layer.
<6> The onium salt compound described in any one of the above <1> to <5>, wherein the onium salt compound is at least one compound selected from the group consisting of a quaternary ammonium salt compound and a sulfonium salt compound. The original planographic printing plate.
<7> The alkali-soluble resin contains at least one resin selected from the group consisting of acetal resin, phenol resin, acrylic resin, and resin having a urea bond, a urethane bond or an amide bond in the main chain, The lithographic printing plate precursor as described in any one of 1> to <6>.
<8> The alkali-soluble resin described in any one of <1> to <7>, wherein the alkali-soluble resin has a structural unit represented by the following formula 1 and a structural unit having a phenolic hydroxyl group in a side chain. The original planographic printing plate.

In Formula 1, R represents an alkyl group or an aryl group.

<9> The lithographic printing plate precursor as described in any one of <1> to <8> above, which is a lithographic printing plate precursor for non-silicate development.
<10> A step of imagewise exposing the lithographic printing plate precursor according to any one of <1> to <9> above, using an infrared laser, and
A method for producing a lithographic printing plate, comprising a step of developing using an alkali developer having a pH of 9 or more containing no silicate compound.
<11> The solution activity of the alkali developer is measured by the conductivity of the alkali developer, and a replenisher is added according to the measured value to adjust the solution activity to a target conductivity to control the solution activity. The method for producing a lithographic printing plate as described in <10> above, which comprises the step of:

According to the embodiment of the present invention, it is possible to provide a lithographic printing plate precursor excellent in development latitude and scratch resistance.
Further, according to another embodiment of the present invention, it is possible to provide a method for producing a planographic printing plate using the planographic printing plate precursor.

It is a schematic block diagram which shows an example of the mechanical roughening apparatus used for manufacture of a support body. It is a graph which shows an example of the alternating waveform current waveform diagram used for electrochemical roughening used for manufacture of a support body. It is a schematic block diagram of the apparatus which connected two or more radial drum rollers used for electrochemical roughening used for manufacture of a support body. FIG. 3 is a schematic view of an electrolytic treatment apparatus in a two-stage power supply electrolysis method applicable to production of a support.

The details of the present disclosure will be described below. The description of the constituent elements described below may be made based on the representative embodiment of the present disclosure, but the present disclosure is not limited to such an embodiment.
In the present disclosure, “to” indicating a numerical range is used to mean that numerical values described before and after the numerical range are included as a lower limit value and an upper limit value.
In the numerical ranges described stepwise in the present disclosure, the upper limit or the lower limit described in one numerical range may be replaced with the upper limit or the lower limit of the numerical range described in other stages. . Further, in the numerical range described in the present disclosure, the upper limit value or the lower limit value of the numerical range may be replaced with the value shown in the examples.
Further, in the present disclosure, the amount of each component in the composition is the total amount of the corresponding plurality of substances present in the composition, unless a plurality of substances corresponding to each component are present in the composition. Means

In addition, in the notation of a group (atomic group) in the present disclosure, the notation that does not indicate substituted and unsubstituted includes not only those having no substituent but also those having a substituent. For example, the “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 disclosure, “(meth) acrylic” is a term used as a concept including both acryl and methacryl, and “(meth) acryloyl” is a term used as a concept including both acryloyl and methacryloyl. is there.
Further, in the present disclosure, with respect to the notation of the group in the compound represented by the formula, when no substitution or substitution is mentioned, and when the group can further have a substituent, there is no particular limitation. As long as the group includes not only an unsubstituted group but also a group having a substituent. For example, in the formula, if “R ^V represents an alkyl group, an aryl group or a heterocyclic group” is described, “R ^V is an unsubstituted alkyl group, a substituted alkyl group, an unsubstituted aryl group, a substituted aryl group, "Represents an unsubstituted heterocyclic group or a substituted heterocyclic group".
In the present disclosure, the “main chain” represents the relatively longest binding chain in the molecule of the polymer compound constituting the resin, and the “side chain” represents an atomic group branched from the main chain.

In addition, the term “process” in the present disclosure is included in this term as long as the intended purpose of the process is achieved, not only when it is an independent process but also when it cannot be clearly distinguished from other processes. Be done.
Moreover, in this indication, "mass%" and "weight%" are synonymous, and "mass part" and "weight part" are synonymous.
Further, in the present disclosure, a combination of two or more preferable aspects is a more preferable aspect.
In addition, the weight average molecular weight (Mw) and the number average molecular weight (Mn) in the present disclosure are columns of TSKgel GMHxL, TSKgel G4000HxL, and TSKgel G2000HxL (both manufactured by Tosoh Corporation) unless otherwise specified. The gel permeation chromatography (GPC) analyzer was used to detect the solvent THF (tetrahydrofuran) with a differential refractometer, and the molecular weight was calculated using polystyrene as a standard substance.
In the present disclosure, the total solid content refers to the total mass of components excluding volatile components such as a solvent in the composition.
In the present disclosure, the term “lithographic printing plate precursor” includes not only the lithographic printing plate precursor but also the discarded plate precursor. In addition, the term "lithographic printing plate" includes not only a lithographic printing plate precursor prepared through an operation such as exposure and development, but also a discarding plate, if necessary. In the case of a waste original plate, the operations of exposure and development are not always necessary. The waste plate is a lithographic printing plate precursor to be attached to an unused plate cylinder when a part of the paper surface is printed in a single color or two colors in color newspaper printing, for example.
Hereinafter, the present disclosure will be described in detail.

(Lithographic printing plate original)
The lithographic printing plate precursor according to the present disclosure has an image recording layer on a support, and the image recording layer is an alkali-soluble resin, an infrared absorber having a weight average molecular weight of 4,000 or more (hereinafter, referred to as "specific polymerized"). Also referred to as "infrared absorber"), and onium salt compounds.

Further, the lithographic printing plate precursor according to the present disclosure is a positive lithographic printing plate precursor, and preferably a thermal positive lithographic printing plate precursor.
Furthermore, the lithographic printing plate precursor according to the present disclosure can be suitably used as a lithographic printing plate precursor for non-silicate development.

As a result of diligent studies by the present inventors, it has been found that the lithographic printing plate precursor excellent in development latitude and scratch resistance can be provided by adopting the above-mentioned constitution.
Although the mechanism of action of the excellent effect of the above configuration is not clear, it is estimated as follows.
In the image recording layer, by containing the specific polymerized infrared absorber and the onium salt compound, in the unexposed portion, the onium salt compound is an alkali-soluble resin forming the image recording layer, and hydrogen which can be relaxed by heat. Not only does it form an interaction such as a bond or an ionic bond to lower the alkali solubility, but the onium salt compound also forms the same interaction with the polymer structure part in the specific polymerized infrared absorber as described above. It is thought that.
On the other hand, in the exposed portion, the specific polymerized infrared absorber generates heat in the vicinity of the onium salt compound, and the interaction between the onium salt and the alkali-soluble resin is efficiently relaxed, and the alkali solubility in the exposed portion is improved. Therefore, it is presumed that the difference in solubility between the exposed portion and the non-exposed portion becomes larger, and the development latitude of the image recording layer (so-called tolerance of developing conditions suitable for image formation) is excellent.
In addition, it is presumed that the strength of the image recording layer and the scratch resistance are excellent by including the specific polymerized infrared absorber and the onium salt compound in the image recording layer.

Further, in the method of manufacturing a lithographic printing plate according to the present disclosure, since a developer containing no silicate compound is used, it is presumed that silicate residue can be easily suppressed.
Further, in the method for producing a lithographic printing plate according to the present disclosure, since a developer that does not contain a large amount of an inhibitor such as a silicate compound is used, it is presumed that the conductivity of the developer activity can be controlled.
Hereinafter, details of each constituent element included in the planographic printing plate precursor according to the present disclosure will be described.

[Image recording layer]
The image recording layer in the lithographic printing plate precursor according to the present disclosure contains an alkali-soluble resin, an infrared absorber having a weight average molecular weight of 4,000 or more (specific polymerized infrared absorber), and an onium salt compound.

<Alkali-soluble resin>
The image recording layer in the lithographic printing plate precursor according to the present disclosure contains an alkali-soluble resin.
The term "alkali-soluble" in the present disclosure means being soluble in a 1 mol / L sodium hydroxide solution at 25 ° C. Further, “soluble” means that 0.1 g or more is dissolved in 100 mL of solvent.
The alkali-soluble resin preferably contains at least one resin selected from the group consisting of an acetal resin, a phenol resin, an acrylic resin, and a resin having a urea bond, a urethane bond or an amide bond in its main chain.

-Acetal resin-
The acetal resin is not particularly limited and known resins can be used, and examples thereof include the acetal resins described in paragraphs 0012 to 0021 of International Publication No. 2014/106554.

-Phenolic resin-
The phenol resin is preferably a phenol resin having a weight average molecular weight of more than 2,000. The phenol resin having a weight average molecular weight of more than 2,000 is a phenol resin containing phenol or a substituted phenol as a structural unit, and is preferably a novolak resin.
The novolak resin is preferably used for the image recording layer in the present disclosure, in the lithographic printing plate precursor, since it causes a strong hydrogen bonding property in the unexposed area and a part of the hydrogen bonding is easily released in the exposed area. It is an alkali-soluble resin.
The novolac resin is not particularly limited as long as it contains phenols as a structural unit in the molecule.
The novolac resin in the present disclosure is a resin obtained by a condensation reaction of phenol, a substituted phenol shown below, and an aldehyde. Specific examples of the phenol include phenol, isopropylphenol, t-butylphenol, Examples thereof include t-amylphenol, hexylphenol, cyclohexylphenol, 3-methyl-4-chloro-6-t-butylphenol, isopropylcresol, t-butylcresol and t-amylcresol. Preferred are t-butylphenol and t-butylcresol.
In addition, examples of aldehydes include aliphatic and aromatic aldehydes such as formaldehyde, acetaldehyde, acrolein, and crotonaldehyde. Formaldehyde and acetaldehyde are preferable.
More specifically, examples of the novolac resin in the present disclosure include a condensation polymer of phenol and formaldehyde (phenol formaldehyde resin), a condensation polymer of m-cresol and formaldehyde (m-cresol formaldehyde resin), p -Polycondensation polymer of cresol and formaldehyde (p-cresol formaldehyde resin), polycondensation polymer of m- / p-mixed cresol and formaldehyde (m- / p-mixed cresol-formaldehyde resin), phenol and cresol (m-, Condensation polymer of p- or m- / p-mixture) and formaldehyde (phenol / cresol (m-, p-, or m- / p-mixture) mixed formaldehyde resin), etc. Is mentioned.
Further, as the novolac resin, as described in US Pat. No. 4,123,279, an alkyl group having 3 to 8 carbon atoms such as t-butylphenolformaldehyde resin and octylphenolformaldehyde resin is further used. Examples thereof include a condensation polymer of phenol and formaldehyde having a substituent.
Among these novolac resins, phenol formaldehyde resin and phenol / cresol mixed formaldehyde resin are particularly preferable.

Further, the above-mentioned phenol resin is preferably a resol resin. Examples of the resole resin include resins obtained by condensing the above-mentioned phenols and aldehydes under basic conditions.
The degree of condensation of phenols and formaldehyde, the molecular weight, the residual monomer residual ratio, etc. of the resole resin can be appropriately set according to the purpose.

Preferred resole resins include, for example, resole resins obtained from phenol and formaldehyde, resole resins obtained from m-cresol and formaldehyde, resole resins obtained from p-cresol and formaldehyde, resole resins obtained from o-cresol and formaldehyde, Examples thereof include a resole resin obtained from bisphenol A and formaldehyde, a resole resin obtained from 4,4′-bisphenol A and formaldehyde, and the like.

A commercial item may be used as the resol resin. Examples of commercially available products are, for example, Sumirite Resin PR-9480, PR-14170, PR-51107, EM-1, PR-EPN, and PR-UFC-504 manufactured by Sumitomo Bakelite Co., Ltd. (Both are trade names), Lekai R-32, etc. (product name) can be used.
Further, the resole resin described in JP-B-6-50394 can be used.

The weight average molecular weight of the phenol resin is preferably more than 2,000 and 50,000 or less, more preferably 2,500 to 20,000, and particularly preferably 3,000 to 10,000. . The dispersity (weight average molecular weight / number average molecular weight) is preferably 1.1 to 10.
The number average molecular weight is a polystyrene equivalent number average molecular weight measured by gel permeation chromatography (GPC) when tetrahydrofuran (THF) is used as a solvent.
Such phenolic resins may be used alone or in combination of two or more.

-A resin having a urea bond, a urethane bond or an amide bond in the main chain-
The resin having a urea bond, urethane bond or amide bond in the main chain has at least one bond of urea bond, urethane bond and amide bond in the main chain from the viewpoint of printing durability of the lithographic printing plate obtained. It is preferable that the main chain has any one of a urea bond and an amide bond, and it is further preferable that the main chain has a urea bond. Examples of the resin include polyurea resin, polyurethane resin, polyamide resin and the like.
The resin having a urea bond, urethane bond or amide bond in the main chain is not particularly limited as long as it is a conventionally known one, but for example, polyurea resin and polyurethane resin of WO 2015/152209 are preferably used. .
As the resin having a urea bond, urethane bond or amide bond in the main chain, only one kind may be used, or two or more kinds may be mixed and used.

-acrylic resin-
As the acrylic resin, those known as those used for the image recording layer of the positive type lithographic printing plate precursor can be used without particular limitation.
The acrylic resin may be used alone or in combination of two or more.
The acrylic resin is preferably a resin in which the content of the constituent unit formed by the (meth) acrylic compound is 50% by mass or more.
Examples of the (meth) acrylic compound include alkyl acrylates and alkyl methacrylates such as methyl acrylate, ethyl acrylate, propyl acrylate, benzyl acrylate, methyl methacrylate, ethyl methacrylate, cyclohexyl methacrylate and benzyl methacrylate. Acrylic acid esters and methacrylic acid esters having an aliphatic hydroxyl group such as 2-hydroxyethyl acrylate or 2-hydroxyethyl methacrylate.
Acrylamide or methacrylamide such as acrylamide, methacrylamide, N-methyl acrylamide, N-ethyl acrylamide, N-phenyl acrylamide. Vinyl esters such as vinyl acetate, vinyl chloroacetate, vinyl butyrate and vinyl benzoate.
Styrenes such as styrene, α-methylstyrene, methylstyrene and chloromethylstyrene.
Other nitrogen atom-containing monomers such as N-vinylpyrrolidone, N-vinylpyridine, acrylonitrile and methacrylonitrile.
N-methylmaleimide, N-ethylmaleimide, N-propylmaleimide, N-butylmaleimide, N-phenylmaleimide, N-2-methylphenylmaleimide, N-2,6-diethylphenylmaleimide, N-2-chlorophenylmaleimide, Maleimides such as N-cyclohexylmaleimide, N-laurylmaleimide, N-hydroxyphenylmaleimide and the like can be mentioned.

From the viewpoint of development latitude and scratch resistance, the alkali-soluble resin preferably contains a structural unit derived from an acrylic resin, and a structural unit represented by the following formula 1 and a phenolic hydroxyl group (“phenolic group” in the side chain). Also referred to as a “hydroxy group”).
The alkali-soluble resin is preferably a copolymer obtained by copolymerizing at least a maleimide compound and a (meth) acrylic compound or a styrene compound, and is obtained by at least copolymerizing a maleimide compound and a (meth) acrylamide compound. It is more preferably a copolymer.

-Structural unit represented by Formula 1-
From the viewpoint of development latitude and scratch resistance, the alkali-soluble resin preferably has a structural unit represented by the following formula 1.
The structural unit represented by the following formula 1 is preferably a structural unit derived from a maleimide compound (a structural unit obtained by copolymerizing a maleimide compound).

In Formula 1, R represents an alkyl group or an aryl group.

The alkyl group and aryl group for R in Formula 1 may have a substituent.
Examples of the substituent include an alkyl group, an aryl group, a halogen atom, a hydroxy group, an alkoxy group, a carboxy group, an alkoxycarbonyl group, an acyl group, an acyloxy group and a cyano group. The above-mentioned substituent may further have a substituent.
The number of carbon atoms (also referred to as “carbon number”) of the alkyl group represented by R in Formula 1 is preferably 1 to 20, more preferably 1 to 12, and further preferably 1 to 8. . Further, the number of carbon atoms of the alkyl group represented by R in Formula 1 is preferably 2 or more from the viewpoint of development latitude.
The aryl group of R in formula 1 preferably has 6 to 20 carbon atoms, more preferably 6 to 12 carbon atoms, and further preferably 6 to 10 carbon atoms.
Further, the aryl group represented by R in Formula 1 may be an aryl group having a monocyclic structure or an aryl group having a structure in which two or more rings are condensed.
From the viewpoint of scratch resistance, R in Formula 1 is preferably an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, and an alkyl group having 1 to 12 carbon atoms, Or, an aryl group having 6 to 12 carbon atoms is more preferable, a methyl group, an n-butyl group, a benzyl group, a phenyl group, or a naphthyl group is further preferable, and an n-butyl group, a benzyl group. , Or a phenyl group is particularly preferable, and a phenyl group is most preferable.
Further, R in Formula 1 is preferably an aryl group from the viewpoint of development latitude and scratch resistance.

Specific examples of the alkyl group represented by R in Formula 1 include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a s-butyl group, a t-butyl group, a cyclohexyl group, and a benzyl group. To be
Specific examples of the aryl group represented by R in Formula 1 include a phenyl group and a naphthyl group.

Examples of the monomer forming the constitutional unit represented by Formula 1 include N-methylmaleimide, Nn-butylmaleimide, N-benzylmaleimide, N-phenylmaleimide, N-naphthylmaleimide, etc. It is not limited to these.

As specific examples of the constitutional unit represented by the formula 1, those shown below are preferably mentioned.

The alkali-soluble resin may have one kind of the structural unit represented by the above formula 1 or two or more kinds.
From the viewpoint of development latitude and scratch resistance, the content of the constitutional unit represented by the above formula 1 (total content in the case of two or more kinds, the same applies below) is based on the total amount of the alkali-soluble resin. The amount is preferably 10 mol% to 80 mol%, more preferably 10 mol% to 60 mol%, particularly preferably 20 mol% to 55 mol%.
In the present disclosure, when the content of the “constituent unit” is defined by the molar ratio, the “constituent unit” is synonymous with the “monomer unit”. Further, in the present disclosure, the “monomer unit” may be modified after polymerization by a polymer reaction or the like. The same applies to the following.

-Structural unit having a phenolic hydroxyl group on the side chain-
The alkali-soluble resin preferably has a structural unit having a phenolic hydroxyl group on its side chain.
The number of phenolic hydroxyl groups contained in the constituent unit having a phenolic hydroxyl group in the side chain is not particularly limited, but is preferably 1 to 4 from the viewpoint of developability and development latitude, and 1 or 2 It is more preferable that the number is 1, and it is particularly preferable that the number is 1.

The structure having a phenolic hydroxyl group in the constituent unit having a phenolic hydroxyl group in the side chain preferably has a nitrogen atom from the viewpoint of development latitude and scratch resistance, and is represented by the following formula (Ph-1). The structure is more preferable.

Wherein ^{(Ph-1), R ph1} each independently represent a monovalent ^{substituent, R ph2} represents a hydrogen atom, an alkyl group or an aryl group, n1 represents an integer of 1 ~ 4, n2 is It represents an integer of 0 to 4, and the wavy line represents the bonding position with another structure.

R ^ph1 in formula (Ph-1) is independently an alkyl group, an aryl group, a halogen atom, an alkoxy group, a carboxy group, an alkoxycarbonyl group, an acyl group, an acyloxy group, a cyano group, or a sulfonamide group. Is more preferable, and an alkyl group, an aryl group, a halogen atom, or a sulfonamide group is more preferable.
From the viewpoint of development latitude and scratch resistance, R ^ph2 in formula (Ph-1) is preferably a hydrogen atom or an alkyl group, and more preferably a hydrogen atom.
N1 in the formula (Ph-1) is preferably 1 or 2, and more preferably 1 from the viewpoint of developability and development latitude.
The bonding position of the phenolic hydroxyl group in the formula (Ph-1) is not particularly limited, but from the viewpoint of developability and development latitude, the ortho position (with respect to the bonding position of the nitrogen atom in the formula (Ph-1) ( The o-position) or the para-position (p-position) is preferable, and the para-position is more preferable.
N2 in the formula (Ph-1) is preferably an integer of 0 to 2, more preferably 0 or 1, and particularly preferably 0.

Further, the structural unit having a phenolic hydroxyl group in the side chain preferably has an amide bond from the viewpoint of development latitude and scratch resistance, and is a structural unit represented by the following formula (Ph-2). More preferable.

Wherein ^{(Ph-2), R ph1} each independently represent a monovalent ^{substituent, R ph2} represents a hydrogen atom, an alkyl group or an aryl ^{group, R ph3} represents a hydrogen atom or a methyl group, n1 represents an integer of 1 to 4, and n2 represents an integer of 0 to 4.

Each ^{^R ph1,} ^R ^ph2, n1 and n2 in Formula (Ph-2), have the same meaning as ^{^R ph1,} ^R ^ph2, n1 and n2 in Formula (Ph-1), a preferable embodiment thereof is also the same.
R ^ph3 in formula (Ph-2) is preferably a hydrogen atom.

Examples of the monomer forming the structural unit having a phenolic hydroxyl group on the side chain include acrylamide, methacrylamide, acrylic acid ester, methacrylic acid ester having a phenolic hydroxyl group, or hydroxystyrene. Specifically, N- (2-hydroxyphenyl) acrylamide, N- (3-hydroxyphenyl) acrylamide, N- (4-hydroxyphenyl) acrylamide, N- (2-hydroxyphenyl) methacrylamide, N- (3- Hydroxyphenyl) methacrylamide, N- (4-hydroxyphenyl) methacrylamide, o-hydroxyphenyl acrylate, m-hydroxyphenyl acrylate, p-hydroxyphenyl acrylate, o-hydroxyphenyl methacrylate, m-hydroxyphenyl methacrylate, p-hydroxy Phenyl methacrylate, o-hydroxystyrene, m-hydroxystyrene, p-hydroxystyrene, 2- (2-hydroxyphenyl) ethyl acrylate, 2- (3-hydroxyphenyl) Preferable are tyl acrylate, 2- (4-hydroxyphenyl) ethyl acrylate, 2- (2-hydroxyphenyl) ethyl methacrylate, 2- (3-hydroxyphenyl) ethyl methacrylate, 2- (4-hydroxyphenyl) ethyl methacrylate and the like. Can be used.

Specific examples of the structural unit having a phenolic hydroxyl group in the above side chain are preferably those shown below.

The alkali-soluble resin may have one kind of structural unit having a phenolic hydroxyl group in the side chain, or may have two or more kinds.
From the viewpoint of development latitude and scratch resistance, the content of the structural unit having a phenolic hydroxyl group in the side chain is preferably 10 mol% to 80 mol% with respect to the total amount of the alkali-soluble resin, and 10 mol%. % To 60 mol% is more preferable, and 20 mol% to 55 mol% is particularly preferable.

The molar ratio of the structural unit represented by Formula 1 and the structural unit having a phenolic hydroxyl group on the side chain in the alkali-soluble resin is not particularly limited, but from the viewpoint of development latitude and scratch resistance, Structural unit represented by the above formula 1: structural unit having a phenolic hydroxyl group on the side chain = 2: 1 to 1: 2 is preferable, and 1.5: 1 to 1: 1.5 is preferable. More preferably, 1.2: 1 to 1: 1.2 is particularly preferable.

-Structural unit having a cyano group-
From the viewpoint of development latitude and scratch resistance, it is preferable that the alkali-soluble resin further has a constitutional unit having a cyano group.
The structural unit having a cyano group is preferably a structural unit represented by the following formula (2-1) from the viewpoint of development latitude and scratch resistance, and is represented by the following formula (2-2). It is more preferably a structural unit.

In formula (2-1), R ^CN represents a hydrogen atom or a methyl group, X ^CN represents a single bond or — (Y ^CN ) _nCN —Z ^CN —, and Y ^CN represents —CONH— or —COO. Represents —, nCN represents 0 or 1, and Z ^CN represents an alkylene group, an arylene group, or a group in which at least two groups selected from the group consisting of an alkylene group, an arylene group, and an ether bond are bonded. .

R ^CN in formula (2-1) is preferably a hydrogen atom.
X ^CN in formula (2-1) is preferably a single bond.
Y ^CN in formula (2-1) is preferably —CONH—.
NCN in the formula (2-1) is preferably 1.
The alkylene group for Z ^CN in formula (2-1) is preferably an alkylene group having 2 to 6 carbon atoms, and more preferably a linear alkylene group having 2 to 6 carbon atoms.
The arylene group in Z ^CN of the formula (2-1) is preferably a phenylene group or a naphthylene group, more preferably a phenylene group.
Z ^CN in the formula (2-1) is preferably an alkylene group, an arylene group or an arylene group-O-alkylene group, and more preferably an alkylene group or an arylene group.

Specific examples of the monomer forming the constitutional unit having a cyano group include acrylonitrile, methacrylonitrile, 2-cyanoethyl acrylate, 2-cyanoethyl methacrylate, 2-cyanoethyl acrylamide, 2-cyanoethyl methacrylamide, p-cyanophenyl methacrylamide. , P-cyanophenyl methacrylate, p-cyanophenyl acrylamide, p-cyanophenyl acrylate, o-cyanophenyl methacrylamide, o-cyanophenyl methacrylate, o-cyanophenyl acrylamide, o-cyanophenyl acrylate, p- (2-cyanoethyl) (Oxy) phenylmethacrylamide, p- (2-cyanoethyloxy) phenylmethacrylate, o- (2-cyanoethyloxy) phenylmethacrylamide o- (2-cyanoethyloxy) phenyl methacrylate, p- (2-cyanoethyloxy) phenylacrylamide, p- (2-cyanoethyloxy) phenyl acrylate, o- (2-cyanoethyloxy) phenylacrylamide, o- (2-cyanoethyl (Oxy) phenyl acrylate and the like, but the present disclosure is not limited thereto.
Among these, acrylonitrile, acrylamide compounds, or methacrylamide compounds are preferable because they have good chemical resistance. Further, among them, acrylonitrile, N-phenylacrylamide compound or N-phenylmethacrylamide compound is particularly preferable.

The alkali-soluble resin may have one type of structural unit having a cyano group, or may have two or more types.
When the alkali-soluble resin has a structural unit having the cyano group, the content of the structural unit having the cyano group is 1 mol% based on the total amount of the alkali-soluble resin from the viewpoint of development latitude and scratch resistance. It is preferably ˜50 mol%, more preferably 5 mol% to 40 mol%, and particularly preferably 10 mol% to 30 mol%.

-Structural unit having a carboxy group-
From the viewpoint of developability, development latitude and scratch resistance, the alkali-soluble resin preferably further has a structural unit having a carboxy group.
The structural unit having a carboxy group is preferably a structural unit represented by the following formula (Ac) from the viewpoint of developability, development latitude and scratch resistance.

In formula (Ac), R ^Ac represents a hydrogen atom or a methyl group.

R ^Ac in formula (Ac) is preferably a hydrogen atom.
Specific examples of the monomer forming the constitutional unit having a carboxy group include acrylic acid, methacrylic acid, maleic anhydride, itaconic acid, etc. Examples thereof include carboxylic acids.
Among them, acrylic acid or methacrylic acid is preferable, and acrylic acid is more preferable.

The alkali-soluble resin may have one kind of the structural unit having a carboxy group, or may have two or more kinds.
When the alkali-soluble resin has a structural unit having a carboxy group, the content of the structural unit having a carboxy group is 1 mol% with respect to the total amount of the alkali-soluble resin from the viewpoint of development latitude and scratch resistance. It is preferably from 50 to 50 mol%, more preferably from 2 to 40 mol%, particularly preferably from 5 to 30 mol%.

-Other building units-
The alkali-soluble resin may have other constitutional units other than those mentioned above.
The other structural unit is not particularly limited, but it is preferable to include a structural unit derived from an alkyl (meth) acrylate compound (a structural unit obtained by copolymerizing an alkyl (meth) acrylate compound).

Specific examples of the monomer forming the above-mentioned other structural units are preferably the following monomers (m1) to (m9).
(M1) Acrylic acid esters and methacrylic acid esters having an aliphatic hydroxyl group such as 2-hydroxyethyl acrylate or 2-hydroxyethyl methacrylate.
(M2) Alkyl acrylates such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, amyl acrylate, hexyl acrylate, octyl acrylate, benzyl acrylate, 2-chloroethyl acrylate and glycidyl acrylate.
(M3) Alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, amyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, 2-chloroethyl methacrylate, glycidyl methacrylate and the like.
(M4) acrylamide, methacrylamide, N-methylolacrylamide, N-ethylacrylamide, N-hexylmethacrylamide, N-cyclohexylacrylamide, N-hydroxyethylacrylamide, N-phenylacrylamide, N-nitrophenylacrylamide, N-ethyl- Acrylamide or methacrylamide such as N-phenylacrylamide, N-vinylpyrrolidone.
(M5) Vinyl ethers such as ethyl vinyl ether, 2-chloroethyl vinyl ether, hydroxyethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, octyl vinyl ether and phenyl vinyl ether.
(M6) Vinyl esters such as vinyl acetate, vinyl chloroacetate, vinyl butyrate and vinyl benzoate.
(M7) Styrenes such as styrene, α-methylstyrene, methylstyrene and chloromethylstyrene.
(M8) Vinyl ketones such as methyl vinyl ketone, ethyl vinyl ketone, propyl vinyl ketone, and phenyl vinyl ketone.
(M9) Olefins such as ethylene, propylene, isobutylene, butadiene and isoprene.

The alkali-soluble resin may have one of the above-mentioned other structural units alone, or may have two or more thereof.
When the alkali-soluble resin has the other structural unit, the content of the other structural unit is 1 mol% to 50 mol% based on the total amount of the alkali-soluble resin from the viewpoint of development latitude and scratch resistance. Is preferable, 2 mol% to 40 mol% is more preferable, and 5 mol% to 30 mol% is particularly preferable.

The alkali-soluble resin preferably has a weight average molecular weight (Mw) of 2,000 or more and a number average molecular weight of 500 or more, a weight average molecular weight of 5,000 to 300,000, and a number average molecular weight of 800 to More preferably, it is 250,000.
The degree of dispersion (weight average molecular weight / number average molecular weight) of the alkali-soluble resin is preferably 1.1 to 10.

The above alkali-soluble resins may be used alone or in combination of two or more.
From the viewpoint of printing durability, the content of the alkali-soluble resin is preferably 1% by mass to 90% by mass, more preferably 3% by mass to 70% by mass, and more preferably 5% by mass. It is particularly preferably from about 50% by mass.
In addition, when the image forming layer has a multilayer structure having an upper layer and a lower layer, it is preferable that the lower layer contains at least the alkali-soluble resin. The content of the alkali-soluble resin in the lower layer is preferably 3% by mass or more, more preferably 10% by mass or more, and further preferably 25% by mass or more, based on the total mass of the lower layer. .

<Infrared absorber having a weight average molecular weight of 4,000 or more>
The image forming layer contains an infrared absorbing agent (specific polymerized infrared absorbing agent) having a weight average molecular weight of 4,000 or more.
The specific polymerized infrared absorber is not particularly limited as long as it is a pigment or dye having a weight average molecular weight of 4,000 or more and absorbing infrared light to generate heat, and various pigments known as infrared absorbers. Alternatively, a dye can be used.
From the viewpoint of development latitude and scratch resistance, the weight average molecular weight of the specific polymerized infrared absorber is preferably 4,000 or more and 50,000 or less, and 6,000 or more and 30,000 or less. More preferably, it is 7,000 or more and 20,000 or less, still more preferably 8,000 or more and 10,000 or less.

From the viewpoint of development latitude, the specific polymerized infrared absorber preferably has an acidic group, more preferably the polymer structure described below has an acidic group, and further preferably the polymer structure described below has a phenol structure. .
Examples of the acidic group include a phenolic hydroxyl group, a sulfonamide group and an active imide group. Among these, from the viewpoint of development latitude, the acidic group is preferably a phenolic hydroxyl group or a sulfonamide group.

The specific polymerized infrared absorber preferably has a dye structure that absorbs infrared light and a polymer structure.
Examples of the dye structure that absorbs infrared rays in the specific polymerized infrared absorber include the dye structures of known and commonly used pigments and dyes.
Specifically, dyes such as azo dye structure, metal complex azo dye structure, pyrazolone azo dye structure, anthraquinone dye structure, phthalocyanine dye structure, carbonium dye structure, quinoneimine dye structure, methine dye structure, cyanine dye structure, and oxonol dye structure. The structure is mentioned.
As these dye structures, at least one dye structure selected from the group consisting of a cyanine dye structure, a phthalocyanine dye structure, an oxonol dye structure, a squarylium dye structure, a pyrylium salt dye structure, a thiopyrylium dye structure and a nickel thiolate complex dye structure. Is more preferable, and a cyanine dye structure is more preferable.

As the compound having a dye structure that absorbs infrared rays in the specific polymerized infrared absorber, a cyanine dye, a ruthenium dye having a halogen atom, etc. described in paragraphs 0016 to 0022 of Chinese Patent Application Publication No. 101770167 may be used. Good. When a ruthenium dye having a halogen atom is used in the specific polymerized infrared absorber, the ruthenium dye is selectively added to the polymer structure part (for example, the polymer main chain of the alkali-soluble resin) included in the specific polymerized infrared absorber. It is believed that the halogen atoms in the ruthenium dye that are bound together promote the dehydrohalogenation reaction.

Examples of the polymer structure of the specific polymerized infrared absorber include the polymer structure of the alkali-soluble resin described above. The alkali-soluble resin forming the polymer structure in the specific polymerized infrared absorber is preferably an alkali-soluble resin having an acidic group. The acidic group has the same meaning as the acidic group described above, and the preferred embodiments are also the same.
Since the specific polymerized infrared absorber has an acidic group, the acidic group interacts with an onium salt compound described below to reduce the solubility of the exposed area, and the unexposed area has a low solubility in a developing solution. It is presumed that the development latitude increases and the development latitude improves.
From the above viewpoint, the alkali-soluble resin is more preferably a phenol resin, further preferably a resol resin.
The above-mentioned phenol resin and resol resin have the same meanings as the specific examples of the phenol resin described above, and the preferred embodiments are also the same.

In addition, the alkali-soluble resin in the specific polymerized infrared absorbing agent preferably has a structural unit represented by the following formula S-1 from the viewpoint of easy graft polymerization reaction.
The alkali-soluble resin in the specific polymerized infrared absorber may include two or more kinds of structural units represented by the following formula S-1 in all structural units constituting the alkali-soluble resin.

In formula S-1, R ^S1's each independently represent a methylol (CH ₂ OH) group or a group represented by the following formula S-2, and R ^S2's each independently represent an alkyl group or halogen. Represents an atom, p1 represents an integer of 1 to 3, p2 represents an integer of 0 to 2, and a wavy line portion represents a bonding position with another structure.

In formula S-2, L ^s represents a single bond or an alkylene group, R ^S3 each independently represents an alkyl group or a methylol group, p3 represents an integer of 0 to 2, and the wavy line portion represents Represents a binding site with R ^S1 in formula S-1.
In formula S-2, L ^s is preferably an alkylene group having 1 to 10 carbon atoms, more preferably an alkylene group having 1 to 5 carbon atoms, and further preferably an alkylene group having 1 to 4 carbon atoms. preferable.
In formula S-2, R ^S3 is preferably an alkyl group having 1 to 4 carbon atoms or a methylol group, and more preferably a methylol group.
In Formula S-2, p3 is preferably 1 or 2, and more preferably 2.
In formula S-2, the position of the OH group in the phenyl group must be at least one position selected from the group consisting of ortho and para positions with respect to the binding site with R ^S1 in formula S-1. Is preferred, and it is more preferred to have at least the para position.

R ^S2 in the formula S-1 is preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms, and further preferably an alkyl group having 1 or 2 carbon atoms. preferable.
R ^S1 in formula S-1 is preferably a methylol group or a group represented by formula S-2. When R ^S1 in the formula S-1 is a group represented by the formula S-2, in the formula S-2, L ^s is an alkylene group having 1 to 10 carbon atoms (more preferably an alkylene group having 1 to 5 carbon atoms). A group, more preferably an alkylene group having 1 to 4 carbon atoms), R ^S3 is an alkyl group having 1 to 4 carbon atoms or a methylol group (more preferably a methylol group), and as p3 Is preferably 1 or 2 (more preferably 2).
P2 in formula S-1 is preferably 0 or 1.
It is preferable that p1 in the formula S-1 is 1 or 2.
In formula S-1, p1 is preferably 1 and p2 is preferably 1.

Specific examples of the constituent units contained in the alkali-soluble resin in the specific polymerized infrared absorbent are shown below, but the constituent units contained in the alkali-soluble resin in the specific polymerized infrared absorbent in the present disclosure are not limited thereto. is not.

In the above structural formula I-1 or I-2, n11 and n12 each independently represent an integer of 1 to 12, and * represents a dye structure that absorbs infrared rays or a bonding portion with another structural unit.

In the specific polymerized infrared absorber, the polymer structure and the infrared absorbing dye structure are preferably formed through an ether bond.
From the viewpoint of development latitude and scratch resistance, the specific polymerized infrared absorber is a compound in which the above structure I-1 or structure I-2 and a cyanine dye described later are formed through an ether bond. Is preferred.
In the specific polymerized infrared absorber, the dye structure preferably has a side chain of the polymer structure.

Specific examples of the specific polymerized infrared absorber include, for example, a compound in which a phenol resin and a cyanine dye are bonded.

The content of the dye structure portion that absorbs infrared rays with respect to the specific polymerized infrared absorber is preferably 14% by mass to 75% by mass, and more preferably 25% by mass to 65% by mass. When the content of the dye structure portion that absorbs infrared rays with respect to the specific polymerized infrared absorber is 14% by mass or more, the development latitude and scratch resistance are more excellent. Further, when the content of the dye structure portion that absorbs infrared rays is 75% by mass or less, the specific polymerized infrared absorbing agent is excellent in alkali solubility, and thus the development dregs suppressing property in the developing solution is more excellent.

The specific polymerized infrared absorbers may be used alone or in combination of two or more.
The content of the specific polymerized infrared absorber (in the case of containing other infrared absorbers, the total amount) in the image forming layer, from the viewpoint of sensitivity, uniformity of the image forming layer, and durability, It is preferably 0.01% by mass to 50% by mass, more preferably 0.1% by mass to 30% by mass, and 1.0% by mass to 30% by mass with respect to the total mass of the image forming layer. It is particularly preferable that

Further, in the image recording layer, the specific polymerized infrared absorber and the infrared absorber having no polymer structure (hereinafter, also simply referred to as “other infrared absorber”) may be used in combination.

As pigments in other infrared absorbers, commercially available pigments, color index (CI) handbook, "latest pigment handbook" (edited by Japan Pigment Technology Association, published in 1977), "latest pigment application technology" (CMC) Published in 1986) and "Printing Ink Technology" published by CMC, published in 1984).

Examples of types of pigments include black pigments, yellow pigments, orange pigments, brown pigments, red pigments, purple pigments, blue pigments, green pigments, fluorescent pigments, metal powder pigments, and polymer-bonded dyes. Specifically, insoluble azo pigments, azo lake pigments, condensed azo pigments, chelate azo pigments, phthalocyanine pigments, anthraquinone pigments, perylene and perinone pigments, thioindigo pigments, quinacridone pigments, dioxazine pigments, isoindolinone pigments. A quinophthalone pigment, a dyed lake pigment, an azine pigment, a nitroso pigment, a nitro pigment, a natural pigment, a fluorescent pigment, an inorganic pigment, and carbon black can be used.
The pigment may be used without surface treatment or may be subjected to conventionally known surface treatment before use.
The particle size of the pigment is preferably 0.01 μm to 10 μm, more preferably 0.05 μm to 1 μm, and further preferably 0.1 μm to 1 μm. Within the above range, the stability of the pigment dispersion in the heat-sensitive layer coating solution, the uniformity of the heat-sensitive layer, and the like are preferable.
As a method for dispersing the pigment, for example, a known dispersion technique used in ink production or toner production described in "Latest Pigment Application Technology" (CMC Publishing, 1986) can be used.

As another infrared absorber, a dye is preferably mentioned.
As other infrared absorbers that can be used in the present disclosure, commercially available dyes and known ones described in the literature (for example, “Handbook of Dyes” edited by The Society of Synthetic Organic Chemistry, published in 1970) can be used. Specific examples thereof include azo dyes, metal complex salt azo dyes, pyrazolone azo dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinoneimine dyes, methine dyes, cyanine dyes, and oxonol dyes.
Specifically, for example, the compounds described in paragraphs 0020 to 0021 of JP-A-7-285275, and "Electronics-related dyes-present state and future prospect-", Chapter 16 CMC (published in 1998) ) And the like described in publicly known materials.
In the present disclosure, among these dyes, those that absorb at least infrared light or near infrared light are preferable in that they are suitable for use in a laser that emits infrared light or near infrared light, and cyanine dyes are particularly preferable. preferable.

Examples of such dyes that absorb at least infrared light or near infrared light include, for example, JP-A-58-125246, JP-A-59-84356, JP-A-59-202829, and JP-A-60-. Cyanine dyes described in JP-A-78787 and the like, methine dyes described in JP-A-58-173696, JP-A-58-181690 and JP-A-58-194595, and JP-A-58-112793, JP-A-58-224793, JP-A-59-48187, JP-A-59-73996, JP-A-60-52940, JP-A-60-63744 and the like. Naphthoquinone dyes described in JP-A-58-112792, squarylium dyes described in JP-A-58-112792, and cyanine dyes described in British Patent 434,875 and the like. Rukoto can.
Further, a near infrared absorption sensitizer described in US Pat. No. 5,156,938 is also preferably used as a dye, and a substituted arylbenzo described in US Pat. No. 3,881,924 is also used. (Thio) pyrylium salt, the trimethine thiapyrylium salt described in JP-A-57-142645 (US Pat. No. 4,327,169), JP-A-58-181051, JP-A-58-220143, and JP-A-58-220143. 59-41363, 59-84248, 59-84249, 59-146063, 59-146061 and pyrylium compounds described in JP-A-59-216146. Cyanine dyes, pentamethine thiopyrylium salts described in U.S. Pat. No. 4,283,475, and Japanese Patent Publication Nos. 5-13514 and 5-19702. Pyrylium compounds disclosed in distribution is, as commercially available products, Epolight III-178 of Eporin Co., Epolight III-130, Epolight III-125 and the like are particularly preferably used.
Another particularly preferable example of the dye is a near-infrared absorbing dye described as formulas (I) and (II) in US Pat. No. 4,756,993.

Particularly preferred among these dyes are cyanine dyes, phthalocyanine dyes, oxonol dyes, squarylium dyes, pyrylium salts, thiopyrylium dyes, and nickel thiolate complexes. Furthermore, the cyanine dye represented by the following formula (a) is most preferable because it gives a high polymerization activity when used in the upper layer of the present disclosure and is excellent in stability and economy.

In the formula (a), X ¹ represents a hydrogen atom, a halogen atom, a diarylamino group (-NPh ₂ ), X ² -L ¹ or a group shown below, X ² represents an oxygen atom or a sulfur atom, L ¹ represents a hydrocarbon group having 1 to 12 carbon atoms, an aromatic ring having a hetero atom, or a hydrocarbon group having 1 to 12 carbon atoms containing a hetero atom. In addition, a hetero atom here represents N, S, O, a halogen atom, and Se.

In the above formula, Xa ⁻ is defined in the same manner as Za ⁻ described later, and R ^a is a substituent selected from the group consisting of a hydrogen atom, an alkyl group, an aryl group, a substituted or unsubstituted amino group, and a halogen atom. Represents a group.

R ²¹ and R ²² each independently represent a hydrocarbon group having 1 to 12 carbon atoms. From the viewpoint of storage stability of the coating liquid for the image recording layer, R ²¹ and R ²² are preferably a hydrocarbon group having 2 or more carbon atoms, and further, R ²¹ and R ²² are bonded to each other to form a 5-membered ring or It is particularly preferable to form a 6-membered ring.

Ar ¹ and Ar ² may be the same or different and each represents an aromatic hydrocarbon group which may have a substituent. Preferred aromatic hydrocarbon groups include a benzene ring and a naphthalene ring. Examples of preferable substituents include a hydrocarbon group having 12 or less carbon atoms, a halogen atom, and an alkoxy group having 12 or less carbon atoms.
Y ¹¹ and Y ^{12, which} may be the same or different, each represents a sulfur atom or a dialkylmethylene group having 12 or less carbon atoms. R ²³ and R ^{24, which} may be the same or different, each represents a hydrocarbon group having 20 or less carbon atoms, which may have a substituent. Preferred substituents include an alkoxy group having 12 or less carbon atoms, a carboxy group, or a sulfo group.
R ²⁵ , R ²⁶ , R ²⁷ and R ^{28, which} may be the same or different, each represents a hydrogen atom or a hydrocarbon group having 12 or less carbon atoms. From the availability of raw materials, hydrogen atom is preferable. Za ⁻ represents a counter anion. However, when the cyanine dye represented by the formula (a) has an anionic substituent in its structure and charge neutralization is unnecessary, Za ⁻ is not necessary. Preferred Za ⁻ is a halide ion, a perchlorate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, and a sulfonate ion in view of the storage stability of the coating solution for the image recording layer, and a perchlorate ion is particularly preferred. , Hexafluorophosphate ion, and arylsulfonate ion.

Specific examples of the cyanine dye represented by the formula (a) which can be preferably used include, for example, paragraphs 0017 to 0019 of JP 2001-133969 A, paragraphs 0012 to 0038 of JP 2002-40638 A, and JP 2002 A. Examples thereof include those described in paragraphs 0012 to 0023 of JP-A-23360.
Particularly preferable as the other infrared absorbing agent is the cyanine dye A shown below.

The other infrared absorbers may be used alone or in combination of two or more.
The content of the other infrared absorbing agent is preferably smaller than the content of the specific polymerized infrared absorbing agent.
When the image forming layer has a multilayer structure having an upper layer and a lower layer, the specific polymerized infrared absorber can be contained in the upper layer and / or the lower layer. The infrared absorbers of the upper layer and the lower layer may be the same specific polymerized infrared absorber as described above, or may be used in combination with different infrared absorbents, and the specific polymerized infrared absorber may be present in the upper layer. preferable.
When the specific polymerized infrared absorber and the other infrared absorber are used in combination, the content ratio of the specific polymerized infrared absorber and the other infrared absorber is 9: 1 to 1: 9 on a mass basis. Is preferable, and more preferably 8: 2 to 2: 8.

<Onium salt compound>
The lithographic printing plate precursor according to the present disclosure contains an onium salt compound.
From the viewpoint of development latitude and scratch resistance, the onium salt compound is preferably at least one compound selected from the group consisting of sulfonium salts and quaternary ammonium salt compounds, and is preferably a sulfonium salt compound. Is more preferable.
The onium salt compounds may be used alone or in combination of two or more.

-Sulfonium salt compound-
The sulfonium salt compound is preferably a sulfonium salt represented by the following formula (S).

In formula (S), R ¹ to R ³ each independently represents an alkyl group having 20 or less carbon atoms or an aryl group having 20 or less carbon atoms, and X ⁻ is a sulfonate ion, a carboxylate ion, or a halogen atom. Represents an inorganic acid ion or a halide ion having.

R ¹ to R ³ in formula (S) are each independently an alkyl group having 20 or less carbon atoms or an aryl group having 20 or less carbon atoms and do not bond to each other to form a ring.
The alkyl group and aryl group in R ¹ to R ³ of the formula (S) may have a substituent. Preferred substituents include a halogen atom, a nitro group, an alkyl group having 12 or less carbon atoms, an alkoxy group having 12 or less carbon atoms, or an aryloxy group having 12 or less carbon atoms. Among them, a halogen atom or a nitro group is preferable, a halogen atom is more preferable, and a chlorine atom is particularly preferable, from the viewpoint of development latitude and scratch resistance.
In the formula (S), R ¹ to R ³ are each independently an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, from the viewpoint of development latitude and scratch resistance. An aryl group having 6 to 20 carbon atoms is more preferable.
The alkyl group may be linear, branched, or have a ring structure, and is preferably an alkyl group having 1 to 8 carbon atoms. It is more preferably 1 to 4 alkyl groups, and particularly preferably a methyl group.
In addition, the aryl group is preferably an aryl group having one or more halogen atoms, more preferably a phenyl group having one or more halogen atoms, from the viewpoint of development latitude and scratch resistance. A phenyl group having the above chlorine atom (chloro group) is particularly preferable.
In addition, the position having a halogen atom in the phenyl group is preferably at least one position selected from the group consisting of ortho and para positions, and more preferably at least in the para position.
The sulfonium salt compound represented by the formula (S) is preferably a triarylsulfonium salt compound from the viewpoint of development latitude and scratch resistance, and the aromatic ring of the aryl group bonded to the sulfur atom has a halogen atom. The compound as a whole is more preferably a triarylsulfonium salt compound having one or more compounds, and is preferably a triarylsulfonium salt compound having an aromatic ring of each of the three aryl groups bonded to a sulfur atom having one or more halogen atoms. More preferably, it is a triarylsulfonium salt compound in which the aromatic ring of each of the three aryl groups bonded to the sulfur atom has at least one chlorine atom.

From the viewpoint of development latitude and scratch resistance, X ⁻ in the formula (S) is preferably a sulfonate ion, an inorganic acid ion having a halogen atom or a halide ion, and more preferably a sulfonate ion.
Further, X ⁻ in the formula (S) preferably has an aromatic group from the viewpoint of development latitude and scratch resistance.
Further, X ⁻ in the formula (S) preferably has a phenolic hydroxyl group from the viewpoint of development latitude and scratch resistance.
Further, X ⁻ in the formula (S) preferably has a diarylketone structure from the viewpoint of development latitude and scratch resistance.
Among them, it is particularly preferable that X ⁻ in the formula (S) has a phenolic hydroxyl group and a diarylketone structure from the viewpoint of development latitude and scratch resistance.

The pKa (acid dissociation constant) of the conjugated acid (XH) of X ⁻ in the formula (S) is preferably less than 5, more preferably −10 or more and less than 5, and is −10 or more and 2 or less. It is particularly preferable that
Note that the pKa in the present disclosure is the pKa in water, and is calculated using ACD / Labs software Ver 8.0 for Microsoft windows ACD / pKa DB ver 8.07 manufactured by Advanced Chemistry Development.

Specific examples of X ⁻ in the formula (S) include chloride ion, bromide ion, iodide ion, BF ₄ ⁻ , PF ₆ ⁻ , trifluoromethanesulfonate ion, p-toluenesulfonate ion, methanesulfonate ion, Alternatively, an anion represented by the following formula (X-1) is preferable, and an anion represented by the following formula (X-1) is particularly preferable.
The anion represented by the following formula (X-1) is an anion having a phenolic hydroxyl group and a diarylketone structure.

The sulfonium salt compound represented by the above formula (S) is preferably a compound having a maximum absorption wavelength of 400 nm or less from the viewpoint of the handleability of the lithographic printing plate precursor under white light. More preferably, it is a compound having a wavelength of 360 nm or less.

The sulfonium salt compounds represented by the above formula (S) may be used alone or in combination of two or more.
The content of the sulfonium salt compound represented by the above formula (S) is preferably 0.1% by mass to 50% by mass, based on the total mass of the image recording layer, from the viewpoint of development latitude and scratch resistance. It is more preferably 0.5% by mass to 40% by mass, and particularly preferably 1% by mass to 30% by mass.

-Quaternary ammonium salt compound-
As the quaternary ammonium salt compound, the quaternary ammonium cation in the quaternary ammonium salt compound may be a monovalent cation or a divalent or higher cation having two or more quaternary ammonium structures. Is preferably a monovalent cation.
The counter anion in the quaternary ammonium salt compound may be a monovalent anion or a divalent or higher valent anion as long as it is an anion capable of neutralizing the charge, but it is a monovalent anion. Is preferred.

The quaternary ammonium cation in the above quaternary ammonium salt compound is preferably a cation represented by the following formula (Am-1), and more preferably a cation represented by the following formula (Am-2). A cation represented by the following formula (Am-3) is particularly preferable.

In formula (Am-1), R ^m1 to R ^m4 each independently represent a substituent containing at least one carbon atom, and two or more of R ^m1 to R ^m4 are bonded to each other to form a ring structure. May be formed.
In formula (Am-2), C ¹ to C ⁶ represent carbon atoms, N ¹ represents a nitrogen atom, R ⁴ to R ¹⁷ each independently represent a hydrogen atom or a substituent, and L ³ represents C ³ and ^{C 4} and a single or double bond linking, ^{^{^{^{or, -C 3 -C 1 -N 1 -C}}}} 2 -C 4 - represents a divalent linking group to form a ring structure containing, m1 and m2 each independently represents an integer of 0 to 5, and n1 and n2 each independently represent 0 or a positive integer.

Examples of the substituent containing at least one carbon atom represented by R ^m1 to R ^m4 in formula (Am-1) include the followings.
For example, an alkyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, specifically, for example, methyl group, ethyl group, n-butyl). Group, iso-propyl group, tert-butyl group, n-octyl group, n-decyl group, n-hexadecyl group, cyclopropyl group, cyclopentyl group, cyclohexyl group, 2-cyclohexylethyl group, etc.), alkenyl. A group (preferably having 2 to 20 carbon atoms, more preferably 2 to 12 carbon atoms, and particularly preferably 2 to 8 carbon atoms), for example, vinyl group, allyl group, 2-butenyl group, 3-pentenyl group, 2-cyclo A hexenylmethyl group, etc.), an alkynyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 12 carbon atoms, particularly preferably 2 to 12 carbon atoms). And examples thereof include a propargyl group and a 3-pentynyl group.), An aryl group (preferably having 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, particularly preferably 6 to 12 carbon atoms, for example, Phenyl group, p-methylphenyl group, naphthyl group, etc.) and the like.

These substituents may be further substituted. When there are two or more substituents, they may be the same or different. If possible, they may be linked to each other to form a ring.

R ^m1 to R ^m4 in formula (Am-1) are preferably an alkyl group, an aryl group, or a group in which any of these is further substituted. From the viewpoint of chemical resistance of the lithographic printing plate obtained, the total carbon number of R ^m1 to R ^m4 is preferably 8 to 80, more preferably 10 to 64, and 12 to 48. It is particularly preferable that

Examples of the substituent in R ⁴ to R ¹⁷ of the formula (Am-2) include the followings.
For example, an alkyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, specifically, for example, methyl group, ethyl group, n-butyl). Group, iso-propyl group, tert-butyl group, n-octyl group, n-decyl group, n-hexadecyl group, cyclopropyl group, cyclopentyl group, cyclohexyl group, 2-cyclohexylethyl group, etc.), alkenyl. A group (preferably having 2 to 20 carbon atoms, more preferably 2 to 12 carbon atoms, and particularly preferably 2 to 8 carbon atoms), for example, vinyl group, allyl group, 2-butenyl group, 3-pentenyl group, 2-cyclo A hexenylmethyl group, etc.), an alkynyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 12 carbon atoms, particularly preferably 2 to 12 carbon atoms). And examples thereof include a propargyl group, a 3-pentynyl group, etc.), an aryl group (preferably having 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, and particularly preferably 6 to 12 carbon atoms, for example, Phenyl group, p-methylphenyl group, naphthyl group, etc.),

An amino group (preferably having 0 to 20 carbon atoms, more preferably 0 to 12 carbon atoms, particularly preferably 0 to 6 carbon atoms, for example, amino group, methylamino group, dimethylamino group, diethylamino group, diphenylamino group, A dibenzylamino group, etc.), an alkoxy group (preferably having 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, particularly preferably 1 to 8 carbon atoms), for example, a methoxy group, an ethoxy group, butoxy. Group, etc.), an aryloxy group (preferably having 6 to 20 carbon atoms, more preferably 6 to 16 carbon atoms, particularly preferably 6 to 12 carbon atoms), for example, a phenyloxy group, a 2-naphthyloxy group. Etc.),

Acyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, and examples thereof include an acetyl group, a benzoyl group, a formyl group, a pivaloyl group). Alkoxycarbonyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 12 carbon atoms, and examples thereof include a methoxycarbonyl group and an ethoxycarbonyl group), aryloxycarbonyl. A group (preferably having 7 to 20 carbon atoms, more preferably 7 to 16 carbon atoms, particularly preferably 7 to 10 carbon atoms, and examples thereof include a phenyloxycarbonyl group); an acyloxy group (preferably having 2 carbon atoms). To 20, more preferably 2 to 16 carbon atoms, and particularly preferably 2 to 10 carbon atoms, such as an acetoxy group, And an acylamino group (preferably having a carbon number of 2 to 20, more preferably a carbon number of 2 to 16, and particularly preferably a carbon number of 2 to 10) such as an acetylamino group and a benzoylamino group. Can be mentioned.),

Alkoxycarbonylamino group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 12 carbon atoms, and examples thereof include a methoxycarbonylamino group) and an aryloxycarbonylamino group. (Preferably having 7 to 20 carbon atoms, more preferably 7 to 16 carbon atoms, particularly preferably 7 to 12 carbon atoms, and examples thereof include a phenyloxycarbonylamino group and the like.), Sulfonylamino group (preferably having carbon number 1 to 20, more preferably 1 to 16 carbon atoms, and particularly preferably 1 to 12 carbon atoms, and examples thereof include a methanesulfonylamino group and a benzenesulfonylamino group.), A sulfamoyl group (preferably having a carbon number of 0 to 20, more preferably 0 to 16 carbon atoms, particularly preferably 0 to 12 carbon atoms, for example Rufamoiru group, methylsulfamoyl group, dimethylsulfamoyl group, and a phenylsulfamoyl group.)

Carbamoyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, and examples thereof include a carbamoyl group, a methylcarbamoyl group, a diethylcarbamoyl group and a phenylcarbamoyl group. ), An alkylthio group (preferably having a carbon number of 1 to 20, more preferably a carbon number of 1 to 16, and particularly preferably a carbon number of 1 to 12, and examples thereof include a methylthio group and an ethylthio group), an arylthio group ( It preferably has 6 to 20 carbon atoms, more preferably 6 to 16 carbon atoms, and particularly preferably 6 to 12 carbon atoms, and examples thereof include a phenylthio group.), A sulfonyl group (preferably 1 to 20 carbon atoms, more preferably It preferably has 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, and examples thereof include a mesyl group and a tosyl group. ), A sulfinyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, and particularly preferably 1 to 12 carbon atoms, and examples thereof include a methanesulfinyl group and a benzenesulfinyl group). A ureido group (preferably having a carbon number of 1 to 20, more preferably a carbon number of 1 to 16 and particularly preferably a carbon number of 1 to 12, and examples thereof include a ureido group, a methylureido group, a phenylureido group, etc.),

Phosphoric acid amide group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, and examples thereof include a diethylphosphoric acid amide group and a phenylphosphoric acid amide group. ), Hydroxy group, mercapto group, halogen atom (for example, fluorine atom, chlorine atom, bromine atom, iodine atom), cyano group, sulfo group, carboxyl group, nitro group, hydroxamic acid group, sulfino group, hydrazino group, imino group, Heterocyclic group (preferably having 1 to 30 carbon atoms, more preferably having 1 to 12 carbon atoms, and the hetero atom includes, for example, a nitrogen atom, an oxygen atom and a sulfur atom, and specifically, for example, imidazolyl. Group, pyridyl group, quinolyl group, furyl group, thienyl group, piperidyl group, morpholino group, benzoxazolyl group, benzimidazole Ryl group, benzothiazolyl group, carbazolyl group, azepinyl group, oxiranyl and the like), silyl group (preferably having 3 to 40 carbon atoms, more preferably having 3 to 30 carbon atoms, particularly preferably 3 to 24 carbon atoms) , For example, a trimethylsilyl group, a triphenylsilyl group, etc.) and the like.

The substituent in R ⁴ to R ¹⁷ of formula (Am-2) is preferably an alkyl group, an aryl group, an alkenyl group, an alkynyl group, or a group in which any of these is further substituted.

In addition, R ⁴ to R ¹⁷ in formula (Am-2) may be the same or different, and may combine with each other to form a ring structure. R ⁴ to R ¹⁷ may be bonded to L ³ or R ⁴ to R ¹⁷ , respectively, to form a ring structure. Also, C ³ carbon atom and C ⁴ carbon atoms, to form a C ¹ carbon atom and C ² carbon atoms and a double bond or triple bond, respectively, C ³ carbon atom and C ⁴ carbon atom and L ³ double When a bond or a triple bond is formed or when L ³ represents a double bond connecting a C ³ carbon atom and a C ⁴ carbon atom, R ⁴ to R ¹¹ are accordingly absent. Good.

When m1 and m2 in the formula (Am-2) are 2 or more, a plurality of R ¹⁴ and R ¹⁷ may be the same or different and may be bonded to each other to form a ring structure.
N1 and n2 in formula (Am-2) are each independently preferably 0, 1, 2 or 3, more preferably 0, 1 or 2, and particularly preferably 0 or 1. When n1 and n2 are 2 or more, a plurality of R ¹² and R ¹³ , and R ¹⁵ and R ¹⁶ may be the same or different, and are bonded to each other to form a ring structure. May be.

Preferable examples of the divalent linking group for L ³ in the formula (Am-2) include —O—, —S—, —N (R ^L1 ) —, and —C (R ^L2 ) (R ^L3 ) —. . Examples of R ^L1 to R ^L3 include a hydrogen atom or a substituent in R ⁴ to R ¹⁷ , which may be bonded to any of R ⁴ to R ¹⁴ to form a ring structure. When C ³ and C ⁴ and L ³ form a double bond, R ^L1 to R ^L3 may not be present.

In R ⁴ to R ¹⁷ and R ^L1 to R ^L3 of formula (Am-2), when two substituents are bonded to the same atom, the two substituents represent the same atom or substituent, A double bond may be formed (eg, R ⁴ ═R ⁵ ═O, and a carbonyl group (—CO—) may be formed).
Further, in R ⁴ to R ¹⁷ and R ^L1 to R ^L3 of the formula (Am-2), when two substituents are bonded to two adjacent atoms, the two substituents are the same atom or It represents a substituent and may form a three-membered ring. (Example: R ⁴ = R ⁸ = O, and an epoxy group may be formed.)

The quaternary ammonium cation in the above quaternary ammonium salt compound preferably has an aromatic ring from the viewpoint of development latitude, scratch resistance and chemical resistance of the lithographic printing plate obtained.
The quaternary ammonium cation and the counter anion in the quaternary ammonium salt compound each preferably have an aromatic ring from the viewpoint of development latitude, scratch resistance, and chemical resistance of the lithographic printing plate obtained.
Further, the quaternary ammonium cation in the quaternary ammonium salt compound preferably has an alicyclic structure from the viewpoint of development latitude, scratch resistance and chemical resistance of the resulting lithographic printing plate, and has a nitrogen atom. More preferably, it has an aliphatic ring structure containing The aliphatic ring is preferably a 5-membered ring to an 8-membered ring, more preferably a 5-membered ring or a 6-membered ring, and particularly preferably a 6-membered ring.
Further, it is particularly preferable that the quaternary ammonium cation in the quaternary ammonium salt compound has an aromatic ring and an aliphatic ring from the viewpoints of development latitude, scratch resistance and chemical resistance of the lithographic printing plate obtained.

The counter anion in the quaternary ammonium salt compound, from the viewpoint of development latitude, scratch resistance and chemical resistance of the lithographic printing plate obtained, sulfonate ion, carboxylate ion, inorganic acid ion having a halogen atom, or, A halide ion is preferable, a sulfonate ion, an inorganic acid ion having a halogen atom, or a halide ion is more preferable, and a sulfonate ion is particularly preferable.
The counter anion in the quaternary ammonium salt compound preferably has an aromatic group from the viewpoint of development latitude, scratch resistance, and chemical resistance of the lithographic printing plate obtained.
Further, the counter anion in the quaternary ammonium salt compound preferably has a phenolic hydroxyl group from the viewpoint of development latitude, scratch resistance and chemical resistance of the lithographic printing plate obtained.
Further, the counter anion in the quaternary ammonium salt compound preferably has a diarylketone structure from the viewpoint of development latitude, scratch resistance and chemical resistance of the lithographic printing plate obtained.
Among them, the counter anion in the quaternary ammonium salt compound particularly preferably has a phenolic hydroxyl group and a diarylketone structure from the viewpoints of development latitude, scratch resistance, and chemical resistance of the lithographic printing plate obtained.

Further, the pKa (acid dissociation constant) of the conjugate acid (XH) of the counter anion in the quaternary ammonium salt compound is preferably less than 5, more preferably -10 or more and less than 5, and more preferably -10 or more. It is particularly preferably 2 or less.
Note that the pKa in the present disclosure is the pKa in water, and is calculated using ACD / Labs software Ver 8.0 for Microsoft windows ACD / pKa DB ver 8.07 manufactured by Advanced Chemistry Development.

Specific examples of the counter anion in the quaternary ammonium salt compound include chloride ion, bromide ion, iodide ion, BF ₄ ⁻ , PF ₆ ⁻ , trifluoromethanesulfonate ion, p-toluenesulfonate ion, methanesulfone. An acid ion or an anion represented by the following formula (X-1) is preferable, and an anion represented by the following formula (X-1) is particularly preferable.
The anion represented by the following formula (X-1) is an anion having a phenolic hydroxyl group and a diarylketone structure.

As the above quaternary ammonium salt compound, specifically, the following compounds are preferably exemplified.

The quaternary ammonium salt compounds may be used alone or in combination of two or more.
The content of the quaternary ammonium salt compound is 0.1% by mass to 50% by mass based on the total mass of the image recording layer from the viewpoint of development latitude, scratch resistance and chemical resistance of the lithographic printing plate obtained. %, More preferably 0.5% by mass to 40% by mass, and particularly preferably 1% by mass to 30% by mass.

The quaternary ammonium cation in the quaternary ammonium salt compound may be a monovalent cation or a divalent or higher cation having two or more quaternary ammonium structures, but it is a monovalent cation. It is preferable.
The counter anion in the quaternary ammonium salt compound may be a monovalent anion or a divalent or higher valent anion as long as it is an anion capable of neutralizing the charge, but it is a monovalent anion. Is preferred.

The onium salt compound according to the present disclosure may be an onium salt compound other than the above quaternary ammonium salt compound and sulfonium salt compound (hereinafter, also referred to as “other onium compound”).
Examples of other onium salt compounds include diazonium salt compounds, iodonium salt compounds, pyridinium salt compounds, and azinium salt compounds.
Examples of other onium salt compounds include known diazonium salts, iodonium salts, primary to tertiary ammonium salts, pyridinium salts, azinium salts, and the like. Among them, triarylsulfonium or diaryliodonium sulfonates. , Carboxylate, BF ₄ ⁻ , PF ₆ ⁻ , ClO ₄ ^{− and the} like are preferable.
Examples of the onium salt compound that can be used as the acid generator in the present disclosure include onium salt compounds represented by the following formula (III) or formula (IV).

In the above formula (III), Ar ¹¹ and Ar ¹² each independently represent an aryl group having 20 or less carbon atoms, which may have a substituent. When the aryl group has a substituent, a preferable substituent is a halogen atom, a nitro group, an alkyl group having 12 or less carbon atoms, an alkoxy group having 12 or less carbon atoms, or an aryloxy group having 12 or less carbon atoms. Is mentioned. Z ^11- is a pair selected from the group consisting of halide ion, perchlorate ion, tetrafluoroborate ion, hexafluorophosphate ion, sulfonate ion, and sulfonate ion having a fluorine atom such as perfluoroalkylsulfonate ion. It represents an ion, and is preferably a perchlorate ion, a hexafluorophosphate ion, an aryl sulfonate ion, and a perfluoroalkyl sulfonic acid.
In the formula (IV), Ar ²¹ represents an optionally substituted aryl group having 1 to 20 carbon atoms. Preferred substituents are a halogen atom, a nitro group, an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aryloxy group having 1 to 12 carbon atoms, an alkylamino group having 1 to 12 carbon atoms, Examples thereof include a dialkylamino group having 2 to 12 carbon atoms, an arylamino group having 6 to 12 carbon atoms, and a diarylamino group (the carbon numbers of two aryl groups are each independently 6 to 12). Z ^21- represents a counter ion having the same ^meaning as Z ^11- .

Specific examples of the onium salt compound that can be preferably used in the image recording layer are the same as the compounds described in paragraphs 0121 to 0124 of International Publication WO2016 / 047392.

More preferable examples of other onium salt compounds include the following compounds (PAG-4) or (PAG-5). Me represents a methyl group.

<Other resins>
In the lithographic printing plate precursor according to the present disclosure, the image recording layer may further contain a resin other than the alkali-soluble resin.
The other resin used in the present disclosure is not particularly limited as long as it is a conventionally known resin, and a known alkali-soluble resin can be preferably used.
As the other resin, the above-mentioned phenol resin is preferably used. The phenol resin in the other resins has the same meaning as the above-mentioned phenol resin, and the preferred embodiments are also the same.

The content of the other resin in the image recording layer in the present disclosure is preferably 90 parts by mass or less based on 100 parts by mass of the total content of the alkali-soluble resin, from the viewpoint of burning suitability and image forming property. The amount is more preferably 50 parts by mass or less, and particularly preferably 30 parts by mass or less.
In the present disclosure, the burning treatment means a high-temperature heat treatment performed after exposure and development of the lithographic printing plate precursor, and the excellent burning suitability means excellent printing durability after the burning treatment.

The image forming layer may contain other components, if desired.
As other components, known additives can be used.
Hereinafter, the acid generator, the acid multiplying agent, and other additives which are optional components in the image forming layer will be described.

<Acid multiplying agent>
The image recording layer in the present disclosure may contain an acid multiplying agent. The acid multiplying agent in the present disclosure is a compound substituted with a residue of a relatively strong acid, and is a compound which is easily eliminated in the presence of an acid catalyst to newly generate an acid. That is, it decomposes by an acid-catalyzed reaction to generate an acid again. One or more acids are increased in one reaction, and the acid concentration is accelerated as the reaction progresses, so that the sensitivity is dramatically improved. The strength of the generated acid is preferably 3 or less as an acid dissociation constant (pKa), and more preferably 2 or less. When the acid dissociation constant is 3 or less, the elimination reaction by the acid catalyst is likely to occur.
Examples of the acid used for such an acid catalyst include dichloroacetic acid, trichloroacetic acid, methanesulfonic acid, ethanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, naphthalenesulfonic acid and phenylsulfonic acid.

The usable acid multiplying agent is the same as those described in paragraphs 0133 to 0135 of WO 2016/047392.

When the acid proliferating agent is added to the image recording layer, the content thereof is preferably 0.01% by mass to 20% by mass, and 0.01% by mass to 10% by mass based on the total mass of the image recording layer. Is more preferable, and 0.1% by mass to 5% by mass is further preferable. When the content of the acid proliferating agent is in the above range, the effect of adding the acid proliferating agent is sufficiently obtained, the sensitivity is improved, and the reduction of the film strength of the image area is suppressed.

<Other additives>
The image recording layer in the present disclosure may contain a development accelerator, a surfactant, a printout agent, a colorant, a plasticizer, a wax agent, etc. as other additives.

-Development accelerator-
An acid anhydride, a phenol, or an organic acid may be added to the image recording layer in the present disclosure for the purpose of improving sensitivity.
Cyclic acid anhydrides are preferred as the acid anhydrides, and specific examples of the cyclic acid anhydrides include phthalic anhydride, tetrahydrophthalic anhydride, and hexahydroanhydride described in US Pat. No. 4,115,128. Phthalic acid, 3,6-endooxytetrahydrophthalic anhydride, tetrachlorophthalic anhydride, maleic anhydride, chloromaleic anhydride, α-phenylmaleic anhydride, succinic anhydride, pyromellitic anhydride and the like can be used. Acetic anhydride etc. are mentioned as an acyclic acid anhydride.
Examples of phenols include bisphenol A, 2,2′-bishydroxysulfone, p-nitrophenol, p-ethoxyphenol, 2,4,4′-trihydroxybenzophenone, 2,3,4-trihydroxybenzophenone, 4- Examples include hydroxybenzophenone, 4,4 ', 4 "-trihydroxytriphenylmethane, 4,4', 3", 4 "-tetrahydroxy-3,5,3 ', 5'-tetramethyltriphenylmethane. .
Organic acids are described in JP-A-60-88942, JP-A-2-96755, and the like. Specifically, p-toluenesulfonic acid, dodecylbenzenesulfonic acid, p-toluenesulfinic acid, Ethyl sulfuric acid, phenylphosphonic acid, phenylphosphinic acid, phenyl phosphate, diphenyl phosphate, benzoic acid, isophthalic acid, adipic acid, p-toluic acid, 3,4-dimethoxybenzoic acid, phthalic acid, terephthalic acid, 4-cyclohexene Examples include -1,2-dicarboxylic acid, erucic acid, lauric acid, n-undecanoic acid, and ascorbic acid. The proportion of the above-mentioned acid anhydride, phenols and organic acids in the total mass of the image recording layer is preferably 0.05% by mass to 20% by mass, more preferably 0.1% by mass to 15% by mass, and 0.1% by mass. 1% by mass to 10% by mass is particularly preferable.

-Surfactant-
The image recording layer in the present disclosure is described in JP-A-62-251740 and JP-A-3-208514 in order to improve the coating property and to broaden the stability of processing under developing conditions. Such nonionic surfactants, amphoteric surfactants as described in JP-A-59-121044 and JP-A-4-13149, JP-A-62-170950, JP-A-11- Fluorine-containing monomer copolymers as described in JP-A-288093 and JP-A-2003-57820 can be added.
Specific examples of the nonionic surfactant include sorbitan tristearate, sorbitan monopalmitate, sorbitan trioleate, stearic acid monoglyceride and polyoxyethylene nonylphenyl ether.
Specific examples of the amphoteric activator include alkyldi (aminoethyl) glycine, alkylpolyaminoethylglycine hydrochloride, 2-alkyl-N-carboxyethyl-N-hydroxyethylimidazolinium betaine and N-tetradecyl-N, N-betaine. Molds (for example, trade name “Amorgen K”: manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) and the like.
The ratio of the surfactant to the total mass of the image recording layer is preferably 0.01% by mass to 15% by mass, more preferably 0.01% by mass to 5% by mass, and 0.05% by mass to 2.0% by mass. % Is more preferable.

-Bakeout agent / colorant-
A printout agent for obtaining a visible image immediately after heating by exposure and a dye or pigment as an image colorant can be added to the image recording layer.
Examples of the print-out agent and the colorant are described in detail in paragraphs 0122 to 0123 of JP 2009-229917 A, and the compounds described therein can be applied to the present disclosure.
These dyes are preferably added in an amount of 0.01% by mass to 10% by mass, more preferably 0.1% by mass to 3% by mass, based on the total mass of the image recording layer. .

-Plasticizer-
A plasticizer may be added to the image recording layer in order to impart flexibility to the coating film. For example, butylphthalyl, polyethylene glycol, tributyl citrate, diethyl phthalate, dibutyl phthalate, dihexyl phthalate, dioctyl phthalate, tricresyl phosphate, tributyl phosphate, trioctyl phosphate, tetrahydrofurfuryl oleate, acrylic acid or methacrylic acid. Oligomers and polymers are used.
These plasticizers are preferably added in a proportion of 0.5% by mass to 10% by mass, more preferably 1.0% by mass to 5% by mass, based on the total mass of the image recording layer. preferable.

-Wax agent-
A compound that reduces the coefficient of static friction of the surface may be added to the image recording layer for the purpose of imparting resistance to scratches. Specifically, as described in US Pat. No. 6,117,913, JP-A 2003-149799, JP-A 2003-302750, or JP-A 2004-12770, Examples thereof include compounds having an ester of a long-chain alkylcarboxylic acid.
The addition amount is preferably 0.1% by mass to 10% by mass, more preferably 0.5% by mass to 5% by mass, based on the total mass of the image recording layer.

<Lower layer and upper layer>
Further, the image recording layer preferably has an upper layer and a lower layer, and an image recording layer in which the lower layer and the upper layer are arranged in this order on a support (hereinafter, also referred to as a “lithographic printing plate precursor having a two-layer structure”). Is more preferable.
The lower layer and the upper layer are preferably formed by separating the two layers.
As a method of forming the two layers separately, for example, a method of utilizing a difference in solvent solubility between a component contained in the lower layer and a component contained in the upper layer, or a method of applying a solvent rapidly after coating the upper layer Examples of the method include drying and removing. It is preferable to use the latter method together because the separation between layers can be more favorably performed.
The alkali-soluble resin, the specific polymerized infrared absorber, and the onium salt compound may be contained in either the lower layer or the upper layer, but from the viewpoint of printing durability and scratch resistance, the upper layer has a specific height. It is preferable that at least the molecularized infrared absorber and the onium salt compound are contained, and that the lower layer contains at least an alkali-soluble resin.
Hereinafter, these methods will be described in detail, but the method of separating and applying the two layers is not limited thereto.

As a method of utilizing the difference in solvent solubility between the component contained in the lower layer and the component contained in the upper layer, a solvent system in which none of the components contained in the lower layer is insoluble is used when the coating liquid for the upper layer is applied. It is a thing. As a result, even if two-layer coating is performed, each layer can be clearly separated to form a coating film. For example, as the lower layer component, a component insoluble in a solvent such as methyl ethyl ketone or 1-methoxy-2-propanol which dissolves the alkali soluble resin as the upper layer component is selected, and the lower layer is coated using a solvent system which dissolves the lower layer component. After drying, the upper layer mainly composed of the alkali-soluble resin is dissolved with methyl ethyl ketone, 1-methoxy-2-propanol or the like, and the resulting layer is coated and dried to form a double layer.

Next, as a method for drying the solvent extremely quickly after applying the second layer (upper layer), high-pressure air is blown from a slit nozzle installed almost at right angles to the running direction of the web, or heating with steam or the like. This can be achieved by applying heat energy as conduction heat from the lower surface of the web from a roll (heating roll) that is internally supplied with the medium, or by combining them.

The coating amount of the lower layer component coated on the support of the lithographic printing plate precursor according to the present disclosure after drying is preferably in the range of 0.5 g / m ² to 4.0 g / m ² , and is 0.6 g. / M ² to 2.5 g / m ² is more preferable. When it is 0.5 g / m ² or more, printing durability is excellent, and when it is 4.0 g / m ² or less, image reproducibility and sensitivity are excellent.
The coating amount after drying of the upper layer component ^is preferably in the range of ^{0.05g / m 2 ~ 1.0g / m} 2, in the range of ^{0.08g / m 2 ~ 0.7g / m} 2 Is more preferable. If it is 0.05 g / ^{m 2} or more, development latitude, and excellent scratch resistance, if it is 1.0 g / ^{m 2} or less, excellent sensitivity.
The combined coating amount of the lower layer and the upper layer after drying is preferably in the range of 0.6 g / m ² to 4.0 g / m ² , and in the range of 0.7 g / m ² to 2.5 g / m ² . Is more preferable. When it is 0.6 g / m ² or more, printing durability is excellent, and when it is 4.0 g / m ² or less, image reproducibility and sensitivity are excellent.

[Support]
The support used in the lithographic printing plate precursor according to the present disclosure is not particularly limited as long as it is a dimensionally stable plate-like material having necessary strength and durability, and for example, paper, plastic (for example, , Polyethylene, polypropylene, polystyrene, etc.) laminated paper, metal plate (eg, aluminum, zinc, copper, etc.), plastic film (eg, cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate) , Cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, etc.), a paper laminated with or vapor-deposited with the above metals, or a plastic film.

As the above support, a polyester film or an aluminum plate is preferable, and among them, an aluminum plate which has good dimensional stability and is relatively inexpensive is particularly preferable. A suitable aluminum plate is a pure aluminum plate or an alloy plate containing aluminum as a main component and containing a trace amount of a foreign element, and may be a plastic film on which aluminum is laminated or vapor-deposited. The foreign elements contained in the aluminum alloy include silicon, iron, manganese, copper, magnesium, chromium, zinc, bismuth, nickel and titanium. The content of the foreign element in the alloy is preferably 10 mass% or less.

Aluminum which is particularly suitable in the present disclosure is pure aluminum, but completely pure aluminum is difficult to produce due to refining technology, and thus may contain slightly different elements.
As described above, the composition of the aluminum plate applied to the present disclosure is not specified, and an aluminum plate of a publicly known and publicly known material can be appropriately used. The aluminum plate used in the present disclosure preferably has a thickness of 0.1 mm to 0.6 mm, more preferably 0.15 mm to 0.4 mm, and particularly preferably 0.2 mm to 0.3 mm. preferable.

Such aluminum plate may be subjected to surface treatment such as surface roughening treatment and anodizing treatment, if necessary. Regarding the surface treatment of the aluminum support, for example, a degreasing treatment with a surfactant, an organic solvent or an alkaline aqueous solution, a rough surface as described in paragraphs 0167 to 0169 of JP2009-175195A Chemical treatment, anodization treatment, etc. are appropriately performed.
The aluminum surface that has been subjected to the anodizing treatment is optionally subjected to a hydrophilic treatment.
Examples of the hydrophilic treatment include an alkali metal silicate (for example, sodium silicate aqueous solution) method, a treatment with potassium fluorozirconate, or polyvinylphosphonic acid as disclosed in paragraph 0169 of 2009-175195. Used.
Further, the support described in JP 2011-245844 A is also preferably used.

[Undercoat layer]
In the lithographic printing plate precursor according to the present disclosure, an undercoat layer can be provided between the support and the image forming layer, if necessary.
As the undercoat layer component, various organic compounds are used, for example, carboxymethyl cellulose, phosphonic acids having an amino group such as dextrin, organic phosphonic acid, organic phosphoric acid, organic phosphinic acid, amino acids, and a hydroxy group. Preferable examples are the hydrochlorides of the amines that it has. These undercoat layer components may be used alone or in combination of two or more. Details of the compound used for the undercoat layer and the method for forming the undercoat layer are described in paragraphs 0171 to 0172 of JP2009-175195A, and these descriptions also apply to the present disclosure.
The coating amount of the undercoat layer is preferably ² mg / m ² to 200 mg / m ² , and more preferably 5 mg / m ² to 100 mg / m ² . When the coating amount is within the above range, sufficient printing durability can be obtained.

[Backcoat layer]
In the planographic printing plate precursor according to the present disclosure, a back coat layer is preferably provided on the surface of the support opposite to the side on which the image recording layer is provided, if necessary. The back coat layer is composed of an organic polymer compound described in JP-A-5-45885 and a metal oxide obtained by hydrolyzing and polycondensing an organic or inorganic metal compound described in JP-A-6-35174. A coating layer is preferably used. Among these coating layers, silicon alkoxy compounds such as Si (OCH ₃ ) ₄ , Si (OC ₂ H ₅ ) ₄ , Si (OC ₃ H ₇ ) ₄ and Si (OC ₄ H ₉ ) ₄ are inexpensively available. It is particularly preferable because the coating layer of the metal oxide obtained therefrom is excellent in the resistance to developing solution.

(Method of preparing lithographic printing plate)
The method for producing a lithographic printing plate according to the present disclosure includes an exposure step of exposing the lithographic printing plate precursor according to the present disclosure in an imagewise manner, and a developing step of developing with a developing solution in this order.
The developer is preferably an alkali developer having a pH of 9 or more from the viewpoint of suppressing silicate debris.
Further, the method for producing a lithographic printing plate according to the present disclosure, from the viewpoint of suppressing silicate residue, a step of imagewise exposing the lithographic printing plate precursor according to the present disclosure using an infrared laser, and does not include a silicate compound. It is preferable to include a step of developing using an alkaline developer having a pH of 9 or more.
Hereinafter, each step of the method for producing a lithographic printing plate according to the present disclosure will be described in detail.

<Exposure process>
The method for producing a lithographic printing plate according to the present disclosure includes an exposure step of imagewise exposing the lithographic printing plate precursor according to the present disclosure.
As a light source of actinic rays used for image exposure of the lithographic printing plate precursor according to the present disclosure, a light source having an emission wavelength in the near infrared to infrared region is preferable, and a solid laser and a semiconductor laser are more preferable. Among them, in the present disclosure, it is particularly preferable to perform image exposure with a solid-state laser or semiconductor laser that emits infrared rays having a wavelength of 750 nm to 1,400 nm.
The laser output is preferably 100 mW or more, and it is preferable to use a multi-beam laser device in order to shorten the exposure time. The exposure time per pixel is preferably within 20 μsec.
The energy applied to the lithographic printing plate precursor is preferably 10 mJ / cm ² to 300 mJ / cm ² . When the content is in the above range, curing can be sufficiently advanced, laser ablation can be suppressed, and damage to an image can be prevented.

The exposure in the present disclosure can be performed by overlapping the light beams of the light source. The overlap means that the sub-scanning pitch width is smaller than the beam diameter. The overlap can be quantitatively expressed by FWHM / sub-scanning pitch width (overlap coefficient) when the beam diameter is expressed by the full width at half maximum (FWHM) of the beam intensity. In the present disclosure, this overlap coefficient is preferably 0.1 or more.

The light source scanning method of the exposure apparatus that can be used in the present disclosure is not particularly limited, and a cylinder outer surface scanning method, a cylinder inner surface scanning method, a flat surface scanning method, or the like can be used. The light source channel may be a single channel or a multi-channel, but in the case of the cylindrical outer surface system, the multi-channel is preferably used.

<Developing process>
The method for producing a lithographic printing plate according to the present disclosure includes a developing step of developing with a developing solution.
The developer used in the developing step is preferably an alkali developer having a pH of 9 or more, more preferably an alkali developer having a pH of 9 or more and containing no silicate compound.
Examples of the silicate compound include silicon dioxide. The developer containing no silicate compound is also referred to as a non-silicate developer, and the development using the non-silicate developer is also referred to as a non-silicate development.
By using a developer that does not contain a silicate compound, the development dust suppressing property is excellent.
As the non-silicate developer, the non-silicate developer described in JP 2001-209172 A is preferably used.
The pH of the alkaline developer is preferably 12.5 to 13.5.

The alkaline developer preferably contains an organic compound having a buffering action and a basic compound.
Examples of the organic compound having a buffering action include saccharides (especially those represented by the general formula (I) or (II)) described as a compound having a buffering action in JP-A-8-220775, and oximes (especially General formula (III)), phenols (particularly represented by general formula (IV)), fluorinated alcohols (particularly represented by general formula (V)) and the like. Among the compounds represented by the general formulas (I) to (V), preferred are the saccharides represented by the general formula (I) or (II) and the phenols represented by the general formula (V). Of the saccharides represented by the general formula (I) or (II), non-reducing sugars such as saccharose or sulfosalicylic acid are more preferable. The above-mentioned non-reducing sugars include trehalose-type oligosaccharides having reducing groups bound to each other, glycosides having reducing groups of saccharides bound to non-saccharides, sugar alcohols hydrogenated to reduce sugars, and the like.

Examples of the trehalose-type oligosaccharides include saccharose and trehalose, and examples of the glycosides include alkyl glycosides, phenol glycosides, mustard oil glycosides, and the like. Examples of the sugar alcohol include D, L-arabite, ribit, xylit, D, L-sorbit, D, L-annite, D, L-idit, D, L-talit, zuricit, and alodulcit. Furthermore, maltitol obtained by hydrogenation of a disaccharide, a reduced form (reduced starch syrup) obtained by hydrogenation of an oligosaccharide, and the like can be preferably mentioned.

Among the above, sugar alcohol and saccharose are preferable as the non-reducing sugar, and among them, D-sorbit, sucrose and reduced starch syrup are more preferable because they have a buffering action in an appropriate pH range.

The organic compounds having a buffering effect may be used alone or in combination of two or more.
The content of the organic compound having a buffering effect is preferably 0.1% by mass to 30% by mass, more preferably 1% by mass to 20% by mass, based on the total mass of the developer.

An alkaline agent as a basic compound can be appropriately selected from the conventionally known compounds and combined with the above-mentioned organic compound having a buffering action.
Examples of the alkaline agent include sodium hydroxide, potassium hydroxide, lithium hydroxide, trisodium phosphate, tripotassium phosphate, triammonium phosphate, disodium phosphate, dipotassium phosphate, diammonium phosphate, Inorganic alkaline agents such as sodium carbonate, potassium carbonate, ammonium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, ammonium hydrogen carbonate, sodium borate, potassium borate, ammonium borate, potassium citrate, tripotassium citrate, sodium citrate Etc. Furthermore, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, triisopropylamine, n-butylamine, monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanol. Preference is also given to organic alkali agents such as neuramis, ethyleneimine, ethylenediamine, pyridine and the like.

Among them, sodium hydroxide or potassium hydroxide is preferable as the basic compound. The reason is that the pH can be adjusted in a wide pH range by adjusting the addition amount to the non-reducing sugar.
In addition, trisodium phosphate, tripotassium phosphate, sodium carbonate, potassium carbonate and the like are preferable because they have a buffering effect.

The above basic compounds may be used alone or in combination of two or more.
The content of the basic compound is not particularly limited, and it may be added to the developing solution in an amount that provides a desired pH.

The developer preferably contains a surfactant from the viewpoint of processability.
The surfactant used in the developer may be any of anionic, nonionic, cationic, and amphoteric surfactants, but as described above, anionic and nonionic surfactants. Agents are preferred.
As the anionic, nonionic, cationic and amphoteric surfactants used in the developing solution in the present disclosure, those described in paragraphs 0128 to 0131 of JP2013-134341A can be used.

From the viewpoint of stable solubility or turbidity in water, the HLB value of the surfactant is preferably 6 or more, more preferably 8 or more.
As the surfactant used in the developing solution, anionic surfactants and nonionic surfactants are preferable, and anionic surfactants containing sulfonic acid or sulfonate, and nonionics having an aromatic ring and an ethylene oxide chain. Surfactants are especially preferred.
The surfactants can be used alone or in combination.
The content of the surfactant in the developer is preferably 0.01% by mass to 10% by mass, more preferably 0.01% by mass to 5% by mass.

In addition to the above, the developer may contain a wetting agent, a preservative, a chelate compound, a defoaming agent, an organic acid, an organic solvent, an inorganic acid, an inorganic salt and the like. However, when the water-soluble polymer compound is added, the plate surface tends to become sticky, especially when the developer is fatigued.

As the wetting agent, the wetting agent described in paragraph 0141 of JP2013-134341A can be preferably used. The wetting agents may be used alone or in combination of two or more. The wetting agent is preferably used in an amount of 0.1% by mass to 5% by mass, based on the total mass of the developer.

As the preservative, the preservative described in paragraph 0142 of JP2013-134341A can be preferably used. It is preferable to use two or more preservatives in combination so as to be effective against various molds and sterilizations. The addition amount of the preservative is an amount that exerts a stable effect on bacteria, molds, yeasts and the like, and varies depending on the types of bacteria, molds, yeasts, but it is 0 for the total mass of the developer. A range of 0.01% by mass to 4% by mass is preferable.

As the chelate compound, the chelate compound described in paragraph 0143 of JP2013-134341A can be preferably used. The chelating agent is selected so that it stably exists in the developer composition and does not impair the printability. The addition amount is preferably 0.001% by mass to 1.0% by mass with respect to the total mass of the developer.

As the defoaming agent, the defoaming agent described in paragraph 0144 of JP2013-134341A can be preferably used. The content of the defoaming agent is preferably in the range of 0.001% by mass to 1.0% by mass with respect to the total weight of the developer.

As the organic acid, the defoaming agent described in paragraph 0145 of JP2013-134341A can be preferably used. The content of the organic acid is preferably 0.01% by mass to 0.5% by mass with respect to the total mass of the developer.

Examples of the organic solvent include aliphatic hydrocarbons (hexane, heptane, “Isopar E, H, G” (manufactured by Esso Chemical Co., Ltd.), gasoline, or kerosene), aromatic hydrocarbons (toluene, Xylene) or halogenated hydrocarbons (methylene dichloride, ethylene dichloride, trichlene, monochlorobenzene, etc.) and polar solvents.

Examples of polar solvents include alcohols (methanol, ethanol, propanol, isopropanol, benzyl alcohol, ethylene glycol monomethyl ether, 2-ethoxyethanol, etc.), ketones (methyl ethyl ketone, cyclohexanone, etc.), esters (ethyl acetate, methyl lactate, propylene). Glycol monomethyl ether acetate, etc.) and others (triethyl phosphate, tricresyl phosphate, N-phenylethanolamine, N-phenyldiethanolamine, etc.) and the like.

If the above organic solvent is insoluble in water, it can be solubilized in water with a surfactant or the like before use. When the developer contains an organic solvent, the concentration of the solvent is preferably less than 40 mass% from the viewpoint of safety and flammability.

As the inorganic acid and the inorganic salt, phosphoric acid, metaphosphoric acid, monobasic ammonium phosphate, dibasic ammonium phosphate, monobasic sodium phosphate, dibasic sodium phosphate, monobasic potassium phosphate, dibasic potassium phosphate, Examples thereof include sodium tripolyphosphate, potassium pyrophosphate, sodium hexametaphosphate, magnesium nitrate, sodium nitrate, potassium nitrate, ammonium nitrate, sodium sulfate, potassium sulfate, ammonium sulfate, sodium sulfite, ammonium sulfite, sodium hydrogensulfate and nickel sulfate. The content of the inorganic salt is preferably 0.01% by mass to 0.5% by mass with respect to the total mass of the developer.

The developing temperature is not particularly limited as long as it can be developed, but is preferably 60 ° C. or lower, more preferably 15 ° C. to 40 ° C. In a developing process using an automatic developing machine, the developing solution may become fatigued depending on the processing amount, and therefore the replenishing solution or a fresh developing solution may be used to recover the processing ability. As an example of the development and the treatment after the development, a method of performing alkali development, removing the alkali in the post-water washing step, performing gum treatment in the gumming step, and drying in the drying step can be exemplified. As another example, a method of simultaneously performing pre-washing, developing and gumming can be preferably exemplified by using an aqueous solution containing carbonate ion, hydrogen carbonate ion and a surfactant. Therefore, the pre-water washing step does not have to be particularly performed, and it is preferable to perform the pre-water washing, the development and the gumming in one bath only after using one solution, and then to perform the drying step. After the development, it is preferable to remove excess developer using a squeeze roller or the like and then perform drying.

Development process can be preferably carried out by an automatic processor equipped with a rubbing member. As the automatic processor, for example, the automatic processor described in JP-A-2-220061 and JP-A-60-59351, which performs rubbing treatment while conveying the planographic printing plate precursor after image exposure, and a cylinder The lithographic printing plate precursor after image exposure set on the above is subjected to rubbing treatment while rotating a cylinder, the automatic processor described in each specification of US Pat. Nos. 5,148,746, 5,568,768 and British Patent 2,297,719. Is mentioned. Above all, an automatic processor using a rotating brush roll as the rubbing member is particularly preferable.

The rotating brush roll used in the present disclosure can be appropriately selected in consideration of the scratch resistance of the image area, the rigidity of the support of the planographic printing plate precursor, and the like. As the rotating brush roll, a known roll formed by planting a brush material on a plastic or metal roll can be used. For example, a metal or plastic in which brush materials are implanted in rows, as described in JP-A-58-159533 and JP-A-3-100554, and JP-B-62-167253. It is possible to use a brush roll in which the groove-shaped material is wound around a plastic or metal roll serving as a core in a radial pattern without a gap.
As the brush material, plastic fibers (for example, polyester type such as polyethylene terephthalate and polybutylene terephthalate, polyamide type such as nylon 6.6 and nylon 6.10, polyacryl type such as polyacrylonitrile, alkyl poly (meth) acrylate) Polyolefin-based synthetic fibers such as polypropylene and polystyrene) can be preferably used. For example, fibers having a hair diameter of 20 μm to 400 μm and a hair length of 5 mm to 30 mm can be preferably used.
The outer diameter of the rotating brush roll is preferably 30 mm to 200 mm, and the peripheral speed of the tip of the brush rubbing the plate surface is preferably 0.1 m / sec to 5 m / sec. It is preferable to use a plurality of rotating brush rolls.

The rotating brush roll may be rotated in the same direction or in the opposite direction with respect to the conveying direction of the lithographic printing plate precursor, but when using two or more rotating brush rolls, at least one rotating brush roll is used. It is preferable that the rotating brush rolls of 1 rotate in the same direction and at least one rotating brush roll rotate in the opposite direction. This further ensures removal of the image recording layer in the non-image area. Further, it is also effective to swing the rotating brush roll in the rotation axis direction of the brush roll.

<Control process>
The method for producing a lithographic printing plate according to the present disclosure, the liquid activity of the alkaline developer is measured by the conductivity of the alkaline developer, and a replenisher is added according to the measured value to obtain the target conductivity. Therefore, it is preferable to include a step of controlling the liquid activity (also referred to as a “control step”).
The alkali developing solution in the control step is preferably an alkali developing solution containing no silicate compound and having a pH of 9 or more.
In the present disclosure, the “replenisher” is a processing solution replenished to keep the developing performance constant. In general, as the replenishing solution, there are those prepared by diluting the replenishing solution undiluted solution with a diluting solution (eg, water), and those using the replenishing solution undiluted solution as it is without diluting it. Is preferably prepared by diluting the replenisher stock solution with a diluent. As a replenishing method, there is a method of replenishing the developing solution with a replenishing solution prepared by diluting in advance, or a method of directly replenishing the developing solution with the replenishing solution stock solution and the diluting solution separately.

As a method for measuring the electric conductivity of the alkaline developer, it is preferable to use an electric conductivity sensor.
As the conductivity sensor for measuring the conductivity of the developer, a known means such as an AC conductivity meter, an AC bridge meter, or other conductivity meter can be used. Further, the measured current value, oscillation frequency, etc. of the above-mentioned measuring device differ in optimum conditions depending on the composition of the developing solution, etc., but the current value is low to some extent in terms of the apparatus and to prevent electrolysis of the water-soluble developing solution. Is preferable, and several hundred mA to several μA is preferable. Further, the frequency is preferably several hundreds Hz to several hundreds kHz from the relationship with the electrostatic capacitance component in the developing solution.

The value of the conductivity of the developer containing the electrolyte depends on the temperature of the aqueous solution, and decreases as the temperature of the solution rises. Therefore, it is more preferable to measure the electric conductivity with a measuring instrument equipped with a temperature sensor and a temperature compensation circuit. Further, in the control device for controlling replenishment, it is also possible to convert the actually measured liquid resistance value and liquid temperature into an electric conductivity value at a predetermined temperature for temperature compensation. The sensor installation position of the AC conductivity meter, AC bridge meter or other conductivity meter may be a place where the AC conductivity value of the developer can be measured by being immersed in the developer at the time of measurement, for example, an automatic developing device solution. The preferred position is the developing solution circulation system, especially in the developing tank or the circulation pipe. As the detection unit, a known measurement cell using platinum, stainless steel or the like for the electrode can be used.

For the control process, reference can be made to JP-A-2005-275384.

After the developing step, it is preferable to provide a drying step continuously or discontinuously. Drying is performed with hot air, infrared rays, far infrared rays, or the like.
As an automatic processor preferably used in the method for producing a lithographic printing plate according to the present disclosure, an apparatus having a developing unit and a drying unit is used, and a lithographic printing plate precursor is developed and gummed in a developing tank. And then dried in the drying section to obtain a lithographic printing plate.

Further, the printing plate after development can be heated for the purpose of improving printing durability. The heating temperature is preferably in the range of 200 ° C to 500 ° C.
The lithographic printing plate thus obtained is set on an offset printing machine and is suitably used for printing a large number of sheets.

Hereinafter, the present disclosure will be described in detail with reference to Examples, but the present disclosure is not limited thereto. In this example, "%" and "part" mean "mass%" and "part by mass", respectively, unless otherwise specified.
In addition, in the polymer compound, the molecular weight is the weight average molecular weight (Mw) and the ratio of the constitutional units is a mole percentage, except for those specifically specified. The weight average molecular weight (Mw) is a value measured as a polystyrene conversion value by a gel permeation chromatography (GPC) method.

<Preparation of support>
Si: 0.06 mass%, Fe: 0.30 mass%, Cu: 0.025 mass%, Mn: 0.001 mass%, Mg: 0.001 mass%, Zn: 0.001 mass%, Ti: It contains 0.03% by mass, the balance is Al and aluminum alloy of unavoidable impurities, prepares a molten metal, and after the molten metal treatment and filtration, the ingot with a thickness of 500 mm and a width of 1,200 mm is directly chilled. It was produced by the (DC) casting method. After shaving the surface with an average thickness of 10 mm by a chamfering machine, it was soaked and held at 550 ° C. for about 5 hours, and when the temperature fell to 400 ° C., it was rolled with a hot rolling mill to a thickness of 2.7 mm. It was a plate. Further, heat treatment was performed at 500 ° C. using a continuous annealing machine, and then cold rolling was performed to finish the thickness to 0.24 mm to obtain a JIS 1050 aluminum plate. The average crystal grain size of the obtained aluminum had a short diameter of 50 μm and a long diameter of 300 μm. After making this aluminum plate a width of 1,030 mm, it was subjected to the following surface treatment.

<Surface treatment>
As the surface treatment, the following various treatments (a) to (k) were continuously performed. After each treatment and washing with water, drainage was performed with a nip roller.

(A) Mechanical surface roughening treatment A device such as shown in FIG. 1 was used to supply a suspension of an abrasive (pumice) having a specific gravity of 1.12 and water as a polishing slurry liquid to the surface of an aluminum plate. Meanwhile, mechanical roughening treatment was performed by a rotating roller-shaped nylon brush. In FIG. 1, 1 is an aluminum plate, 2 and 4 are roller brushes, 3 is a polishing slurry liquid, 5, 6, 7 and 8 are support rollers. The average particle size of the abrasive was 30 μm, and the maximum particle size was 100 μm. The material of the nylon brush was 6.10 nylon, the bristle length was 45 mm, and the bristle diameter was 0.3 mm. The nylon brush was prepared by forming holes in a stainless steel cylinder having a diameter of 300 mm and densely implanting the bristles. Three rotating brushes were used. The distance between the two support rollers (φ200 mm) below the brush was 300 mm. The brush roller was pressed until the load of the drive motor for rotating the brush became 7 kW plus with respect to the load before the brush roller was pressed against the aluminum plate. The rotating direction of the brush was the same as the moving direction of the aluminum plate. The rotation number of the brush was 200 rpm (revolutions per minute).

(B) Alkaline etching treatment The aluminum plate obtained above was subjected to etching treatment by spraying using an aqueous solution having a sodium hydroxide concentration of 2.6% by mass, an aluminum ion concentration of 6.5% by mass, and a temperature of 70 ° C. to obtain an aluminum plate. Was dissolved at 10 g / m ² . Then, washing with water was performed by spraying.

(C) Desmutting treatment Desmutting treatment was carried out by spraying with a 1% by weight nitric acid concentration aqueous solution (containing 0.5% by weight of aluminum ion) at a temperature of 30 ° C., followed by washing with water by spraying. The nitric acid aqueous solution used for the desmutting treatment was the waste liquid of the step of performing the electrochemical surface roughening treatment using an alternating current in the nitric acid aqueous solution.

(D) Electrochemical surface roughening treatment Electrochemical surface roughening treatment was continuously performed using an alternating voltage of 60 Hz. At this time, the electrolytic solution was a 10.5 g / L nitric acid aqueous solution (containing 5 g / L of aluminum ions and 0.007% by mass of ammonium ions), and the liquid temperature was 50 ° C. The AC power supply waveform is the waveform shown in FIG. 2, in which the time TP required for the current value to reach the peak from zero is 0.8 msec, the duty ratio is 1: 1, and a trapezoidal rectangular wave AC is used, with the carbon electrode as the counter electrode. An electrochemical graining treatment was performed. Ferrite was used for the auxiliary anode. The electrolytic cell used was that shown in FIG.
The current density was 30 A / dm ² at the peak value of the current, and the amount of electricity was 220 C / dm ^{2 as} the total amount of electricity when the aluminum plate was the anode. 5% of the current flowing from the power source was shunted to the auxiliary anode. Then, washing with water was performed by spraying.

(E) Alkaline etching treatment An aluminum plate is subjected to etching treatment by spraying with an aqueous solution having a caustic soda concentration of 26 mass% and an aluminum ion concentration of 6.5 mass% at 32 ° C to dissolve the aluminum plate at 0.50 g / m ² . Removes the smut component composed mainly of aluminum hydroxide generated when electrochemical roughening treatment was performed using the alternating current in the previous stage, and melts the edge part of the generated pit to smooth the edge part. did. Then, washing with water was performed by spraying.

(F) Desmutting treatment Desmutting treatment was performed by spraying with a 15% by weight nitric acid aqueous solution (containing 4.5% by weight of aluminum ion) at a temperature of 30 ° C., and then washed with water by spraying. As the nitric acid aqueous solution used for the desmut, a waste liquid from the step of performing an electrochemical graining treatment using an alternating current in the nitric acid aqueous solution was used.

(G) Electrochemical surface roughening treatment Electrochemical surface roughening treatment was continuously performed using an alternating voltage of 60 Hz. The electrolytic solution at this time was a 5.0 g / L hydrochloric acid aqueous solution (containing 5 g / L of aluminum ions), and the temperature was 35 ° C. The AC power supply waveform is the waveform shown in FIG. 2, and the time TP from when the current value reaches zero to the peak is 0.8 msec, the duty ratio is 1: 1, and the trapezoidal rectangular wave AC is used to drive the carbon electrode. Electrochemical roughening treatment was performed as a counter electrode. Ferrite was used for the auxiliary anode. The electrolytic cell used was that shown in FIG.
The current density was 25 A / dm ² at the peak value of the current, and the amount of electricity was 50 C / dm ^{2 as} the total amount of electricity when the aluminum plate was the anode. Then, washing with water was performed by spraying.

(H) Alkaline etching treatment An aluminum plate is subjected to etching treatment by spraying at 32 ° C. using an aqueous solution having a caustic soda concentration of 26 mass% and an aluminum ion concentration of 6.5 mass% to dissolve the aluminum plate at 0.10 g / m ² . Removes the smut component composed mainly of aluminum hydroxide generated when electrochemical roughening treatment was performed using the alternating current in the previous stage, and melts the edge part of the generated pit to smooth the edge part. did. Then, washing with water was performed by spraying.

(I) Desmutting treatment Desmutting treatment was carried out by spraying with a 25% by mass aqueous solution of sulfuric acid (containing 0.5% by mass of aluminum ion) at a temperature of 60 ° C., followed by washing with water by spraying.

(J) Anodizing treatment The anodizing device having the structure shown in FIG. 4 (first and second electrolysis section lengths of 6 m each, first and second feeding section lengths of 3 m, and first and second feeding electrode lengths of 2.4 m) was used. Was used to perform anodizing treatment. Sulfuric acid was used as the electrolytic solution supplied to the first and second electrolysis sections. Each of the electrolytic solutions had a sulfuric acid concentration of 50 g / L (containing 0.5% by mass of aluminum ion) and a temperature of 20 ° C. Then, washing with water was performed by spraying.
In the anodizing device, currents from the power source 67a and the power source 67b flow to the first power feeding electrode 65a provided in the first power feeding portion 62a, flow to the aluminum plate 11 via the electrolytic solution, and then to the first electrolytic portion 63a. Then, an anodic oxide film is formed on the surface of the aluminum plate 11, passes through the

electrolytic electrodes

66a and 66b provided in the first electrolytic portion 63a, and returns to the

electrodes

67a and 67b.
The amount of electricity supplied from the

power sources

67a and 67b to the first power supply unit 62a is equal to the amount of electricity supplied from the

power sources

67c and 67d to the second power supply unit 62b, and the first electrolysis unit 63a and the second electrolysis unit 63a The current densities at 63b were both about 30 A / dm ² . In the second power feeding portion 62b, power is fed through the oxide film surface of 1.35 g / m ² generated in the first electrolytic portion 63a. The final amount of oxide film was 2.7 g / m ² .

(K) Alkali metal silicate treatment By immersing the aluminum support obtained by anodizing treatment in a treatment tank of a 1% by mass aqueous solution of sodium silicate No. 3 at a temperature of 30 ° C for 10 seconds, the alkali metal silicate is treated. Acid salt treatment (silicate treatment) was performed. After that, washing with well water was performed by spraying to obtain a support having a surface silicate hydrophilized. On the aluminum support treated with an alkali metal silicate obtained as described above, an undercoat liquid having the following composition was applied and dried at 80 ° C. for 15 seconds to form a coating film. The coating amount of the coating film after drying was 15 mg / m ² .

-Undercoat composition-
・ The following compounds: 0.3 parts ・ Methanol: 100 parts ・ Water: 1 part

Note that Et represents an ethyl group.

(Examples 1-1 to 13-1 and Comparative Examples 1-1 and 2-1)
<Formation of image recording layer (multilayer)>
The web-shaped substrate thus obtained was coated with a lower layer coating solution having the following composition by a bar coater so that the coating amount was 0.85 g / m ² , followed by drying at 160 ° C. for 44 seconds and immediately cooling with cold air at 17 ° C.-20 ° C. It was cooled until the temperature of the support reached 35 ° C.
Then, a coating solution for the upper layer having the following composition was applied by a bar coater to a coating amount of 0.22 g / m ² , dried at 148 ° C. for 25 seconds, and then gradually cooled by a wind at 20 ° C. to 26 ° C. The lithographic printing plate precursors of Examples and Comparative Examples were produced.

<Coating liquid for lower layer>
-Alkali-soluble resin described in Table 1: The addition amount described in Table 1 (for example, it is 1.92 parts in Example 1-1).
・ Novolak resin: 0.192 part ・ Cyanine dye A: 0.134 part ・ 4,4'-bishydroxyphenyl sulfone: 0.126 part ・ Tetrahydrophthalic anhydride: 0.190 part ・ p-toluenesulfonic acid: 0 0.008 part 3-methoxy-4-diazophenylamine hexafluorophosphate: 0.032 part-Ethyl violet counter ion changed to 6-hydroxynaphthalenesulfonic acid: 0.0781 part-Polymer 1 (shown below Polymer): 0.035 parts, methyl ethyl ketone: 25.41 parts, 1-methoxy-2-propanol: 12.97 parts, γ-butyrolactone: 13.18 parts

<Upper layer coating liquid>
M, p-cresol novolac resin (m / p ratio = 6/4, weight average molecular weight 4,500, containing 0.8% by mass of unreacted cresol): 0.3479 parts Polymer 3 (polymer shown below): 0.1403 parts-Specific polymerized infrared absorbent described in Table 1: Addition amount described in Table 1 (for example, 0.5 parts in Example 1-1).
Polymer 1: 0.015 part Polymer 2 (polymer shown below): 0.00328 part Onium salt compound consisting of cation and anion described in Table 1: Addition amount described in Table 1 (for example, Example 1 -1 is 0.08 copies.)
-Surfactant (Megafac F-780F, manufactured by DIC Corporation: 0.008 parts) -Methyl ethyl ketone: 6.79 parts-1-Methoxy-2-propanol: 13.07 parts

(Example 1-2 to Example 13-2 and Comparative Examples 1-2 and 2-2)
On the support obtained in the same manner as in Example 1-1, a single-layer coating solution having the following composition was applied to give a coating amount of 1.2 g / m ^2, and dried to form a recording layer. The lithographic printing plate precursors of Example 1-2 to Example 13-2 and Comparative Examples 1-2 and 2-2 were obtained.

<Single layer coating liquid>
-Alkali-soluble resin shown in Table 2: 2.625 parts-m, p-cresol novolac resin: 0.525 part-Specific polymerized infrared absorber shown in Table 2: Addition amount shown in Table-2: 0 .15 parts 4,4'-bishydroxyphenyl sulfone: 0.225 part tetrahydrophthalic anhydride: 0.3 part p-toluenesulfonic acid: 0.015 part 3-methoxy-4-diazophenylamine hexa Fluorophosphate: 0.045 parts-Ethyl violet counter ion changed to 6-hydroxynaphthalene sulfonic acid: 0.1125 parts-Surfactant (Megafuck F-780F, manufactured by DIC Corporation): 0.0525 Parts Methyl ethyl ketone: 22.5 parts 1-methoxy-2-propanol: 11.25 parts γ-butyrolactone: 11.25 parts Onium salt compound consisting of one and the anion: 0.516 parts

<Evaluation of original planographic printing plate>
-exposure-
The lithographic printing plate precursors of Examples and Comparative Examples were changed in exposure energy with a Trendsetter manufactured by Creo, and a test pattern was drawn in an image.

-Development processing-
After that, with regard to the planographic printing plate precursors of Examples and Comparative Examples, a PS processor manufactured by FUJIFILM Co., Ltd. charged with a developer XP-D manufactured by FUJIFILM Corporation (diluted to have an electric conductivity of 43 mS / cm) Development was carried out using LP940H at a development temperature of 30 ° C. and a development time of 12 seconds.

-Development latitude evaluation-
In the above-mentioned development processing, the development ratio is adjusted by changing the dilution ratio of the developing solution to adjust the conductivity, the image area is not eluted, and there is no stain or coloration due to the poorly developed photosensitive layer residual film. In the developing solution which has been developed, the difference (mS / cm) between the maximum value of conductivity and the minimum value of conductivity (hereinafter, also referred to as “conductivity difference”) is used as the development latitude, and the following evaluation criteria are used. The evaluation was performed according to. It can be said that the higher the evaluation score, the better the development latitude, and the evaluation score of 3 or more, the better the development latitude.
(Evaluation criteria)
5: The difference in conductivity (mS / cm) is 7 or more.
4.5: The difference in conductivity (mS / cm) is 6 or more and less than 7.
4: The difference in conductivity (mS / cm) is 5 or more and less than 6.
3.5: The difference in conductivity (mS / cm) is 4 or more and less than 5.
3: The difference in conductivity (mS / cm) is 3 or more and less than 4.
2.5: The difference in conductivity (mS / cm) is 2 or more and less than 3.
2: The difference in conductivity (mS / cm) is 1 or more and less than 2.
1.5: The difference in conductivity (mS / cm) is less than 1.
1: Not developable

-Scratch resistance evaluation-
The lithographic printing plate precursor thus obtained was conditioned for 2 hours in an environment of 25 ° C. and 60% RH, punched out into 2.5 cm × 2.5 cm, and manufactured by Shinto Kagaku Co., Ltd. as a continuous load type scratch strength tester TYPE. Mounted on -18, set so that the back surface of the punched lithographic printing plate precursor comes into contact with the front surface of the lithographic printing plate precursor that has not been punched out, and lithographically plate it at a pressure of 0 gf to 1,500 gf (0N to 14.7N). Several parts of the printing plate precursor were scratched and scratched. The lithographic printing plate precursor with scratches was set on the Trendsetter 3244 manufactured by Creo, and the output was 7 W at the resolution of 2,400 dpi (dot per inch, 1 inch was 2.54 cm), the outer surface drum rotation speed was 150 rpm (revolutions per minute), and the plate surface energy was set. Image exposure was performed at 110 mJ / cm ² .
The lithographic printing plate precursor after image exposure was mounted on an offset rotary printing machine manufactured by Tokyo Kikai Seisakusho, and Soybee KKST-S (red) manufactured by Inktec Co., Ltd. was used as printing ink for newspapers, and Sakata Inx as dampening water ( Using Eco Seven N-1 manufactured by Co., Ltd., printing was performed on newsprint paper at a speed of 100,000 sheets / hour. In the printing process, the 1,000th printed material was sampled, and the degree of scratch stains caused by scratches was visually observed.
The scratch resistance is evaluated by a sensory evaluation of 1 to 5, and 3 or more is a practically preferable level.
(Evaluation criteria)
5: No visible scratch stain is seen in the image area.
4.5: Although it cannot be visually confirmed, there is one scratch stain in the image area that can be confirmed with a magnifying glass of 25 magnifications.
4: Although it cannot be visually confirmed, there is one scratch on the image area that can be confirmed with a magnifying glass of 6 magnifications.
3: Although it cannot be visually confirmed, there are two or more and five or less scratches and stains in the image area that can be confirmed with a magnifying glass of 6 magnifications.
2: Scratch stains that can be visually confirmed are found at multiple locations in the image area.
1: Visual stains are visible on the entire surface of the image area.

-Processing stability evaluation-
In the exposure step, a test pattern containing an FM screen chart of 175 lpi (lines per inch) / 2400 dpi with a dot area ratio of 1% to 99% was imagewise drawn (exposed). The lithographic printing plate precursors of Examples and Comparative Examples were manufactured by Fuji Film Co., Ltd., which was prepared by using Developer XP-D developer (diluted to have an electric conductivity of 43 mS / cm, pH 13.1). Development was performed using a PS processor LP940H at a development temperature of 30 ° C. and a development time of 12 seconds. As the development process progressed, the developer replenisher XP-DR manufactured by FUJIFILM Corporation was used to replenish the developer with an automatic replenishment system.
After continuous treatment for 7 days under the following treatment conditions, the halftone dot area ratio (%) of the FM screen 50% halftone dots on the plate was measured using iCPlate2 manufactured by X-RITE, and 50% halftone dots during continuous treatment were measured. The difference between the maximum value and the minimum value of the dot area ratio (%) of the dots (hereinafter, also simply referred to as “difference in 50% dot reproduction”) was obtained and evaluated according to the following evaluation criteria.
The higher the evaluation score is, the smaller the difference of 50% halftone dot reproduction is, and the better the processing stability is. The evaluation score of 3 or more is considered to be a practically preferable level.
<< processing conditions >>
Development temperature 30 ℃
Development time 12 seconds Development tank capacity 20L
Plate material conveying speed 1,400 mm / min Replenisher dilution ratio Development replenisher XP-DR: Water = 1: 6.5
Replenishment amount with time during operation 50 mL / hour Replenishment amount with time during stoppage 15 mL / hour Treatment replenishment amount 20 mL / m ²
<< Processing pattern >>
Monday-Wednesday: The exposed lithographic printing plate (plate material) (0.8 m ² ) was developed at 26 sheets / day.
Thursday: The exposed lithographic printing plate (plate material) (0.8 m ² ) was developed at 84 sheets / day.
Friday: The exposed lithographic printing plate (plate material) (0.8 m ² ) was developed at 14 sheets / day.
(Evaluation criteria)
5: 50% Difference in halftone dot reproduction is less than 5%.
4.5: 50% Difference in halftone dot reproduction is 5% or more and less than 5.5%.
4: 50% difference in dot reproduction is 5.5% or more and less than 6%.
3.5: 50% Difference in halftone dot reproduction is 6% or more and less than 6.5%.
3: 50% Difference in halftone dot reproduction is 6.5% or more and less than 7%.
2: 50% Difference in dot reproduction is 7% or more.
1: 50% difference in dot reproduction is 8% or more.

-Development residue (silicate residue) inhibition evaluation-
Using a lithographic printing plate precursor cut into a size of 30 cm × 65 cm, 60-plate processing was carried out under the development processing conditions in the above processing stability evaluation, and then the image area of the processed lithographic printing plate was visually observed, The presence or absence of scratches, which are considered to be caused by the insoluble matter, was visually observed to evaluate the development residue suppressing property.

The structural unit a in Table 1 and Table 2 represents the structural unit represented by the above formula 1, and the structural unit b represents the structural unit having a phenolic hydroxyl group in the side chain.
The composition ratios (mol ratios) of the alkali-soluble resins shown in Tables 1 and 2 are listed in order from the structural units shown on the left of Tables 1 and 2, and, for example, in Example 1-1. A-1 is 28 mol%, b-1 is 26 mol%, c-1 is 20 mol%, c-2 is 6 mol%, and c-3 is 20 mol%.
Further, details of each abbreviation shown in Table 1 and Table 2 are shown below.
a-1: Structural unit shown below

B-1: Structural units shown below

C-1 to c-3: Structural units shown below

<< Specific IR Dye (1) >>
The alkali-soluble resin used in the synthesis of the specific IR dye (1) is a resole resin containing a constitutional unit represented by the structural formula II shown below: RM-1 (manufactured by Lekai, methylol compound of m-cresol resin). Was used. A solution was prepared by dissolving 100 g of the above RM-1 in 400 mL of N, N-dimethylformamide, and at 40 ° C., 0.2 g of sodium hydroxide was slowly added to the solution, and the obtained reaction product was added for 30 minutes. It was stirred. 2- [2- [2-chloro-3- [2- (1,3-dihydro-1,1,3-trimethyl-2H-) phenyl-fluorene-2-fork dissolved in 100 mL of N, N-dimethylformamide ) -Acetal] -1-cyclopenten-1-yl-ethene] -1,1,3-trimethyl-1H-phenylindole tetramethylbenzenesulfonate solution (cyanine dye) is slowly added to the solution in which RM-1 is dissolved. Was added and the reaction was carried out for 10 hours. The solution was then cooled at room temperature and the product separated by settling in water. The resulting product was collected by vacuum filtration, rinsed with water and dried in air to give the specific IR dye (1).

In the above structural formula II, R represents a hydrocarbon group having 1 to 12 carbon atoms, an alkoxy group, an aryl group, or a halogen atom, and m and n each independently represent an integer of 1 to 12.

<< Specific IR Dye (2) >>
The alkali-soluble resin used for the synthesis of the specific IR dye (2) is a compound represented by the above-mentioned structural formula I-1: BTB-29 (a methylol compound of m-cresol resin manufactured by Weihai Amagi Chemical Co., Ltd.). Was used. A solution was prepared by dissolving BTB-29 in 400 mL of N, N-dimethylformamide. At 40 ° C., 0.2 g sodium hydroxide was slowly added to the solution and the reaction was stirred for 30 minutes.
2- [2- [2-chloro-3- [2- (1,3-dihydro-1,1,3-trimethyl-2H-) phenyl-fluorene-2-fork dissolved in 100 mL of N, N-dimethylformamide ) -Acetal] -1-cyclopenten-1-yl-ethene] -1,1,3-trimethyl-1H-phenylindole tetramethylbenzenesulfonate solution (cyanine dye) to a solution in which BTB-29 is dissolved. It was added slowly and the reaction was run for 10 hours. The solution is then cooled at room temperature and the product is separated by settling in water. The product was collected by vacuum filtration, rinsed with water and dried in air to give the specific IR dye (2).

Cyanine dye A: the following compound

Ca-1 and ca-11: the following cations

cb-1: the following cation

An-1: the following anion

For the planographic printing plate precursors of Examples 1-5, 1-6, 2-5 and 2-6, the developer DP-4 (containing silicate) manufactured by Fuji Film Co., Ltd. Development was carried out at a development time of 25 seconds using a PS processor LP940H manufactured by FUJIFILM Corporation, which was prepared by doubling the dilution.

From the results shown in Table 1 and Table 2, the lithographic printing plate precursor of the example, which is the lithographic printing plate precursor according to the present disclosure, was excellent in development latitude and scratch resistance as compared with the lithographic printing plate precursor of Comparative Example. It can be seen that a lithographic printing plate can be obtained.
Further, it can be seen that the lithographic printing plate precursor of the example which is the lithographic printing plate precursor according to the present disclosure can provide a lithographic printing plate excellent in processing stability.

The disclosure of Japanese Patent Application No. 2018-196166 filed on Oct. 17, 2018 is incorporated herein by reference in its entirety.
All documents, patent applications, and technical standards mentioned in this specification are to the same extent as if each individual document, patent application, and technical standard were specifically and individually noted to be incorporated by reference. Are incorporated herein by reference.

1

Aluminum Plate

2, 4 Roller Brush 3

Polishing Slurry Liquid

5, 6, 7, 8 Support Roller 11 Aluminum Web 12

Radial Drum Rollers

13a, 13b Main Electrode 14

Electrolytic Treatment Liquids

15a, 15b Electrolyte Supply Port 16 Slit 17 Electrolyte Passage 18

Auxiliary anode

19a, 19b Thyristor 20

AC power supply

40, 41

Main electrolysis tank

50, 51 Auxiliary anode tank 62a First power feeding part 62b Second power feeding part 63a First electrolysis part 63b

Second electrolysis part

64a, 64b Support roller 65a One feeding electrode 65b

Second feeding electrodes

66a, 66b, 66c, 66d

Electrolytic electrodes

67a, 67b, 67c, 67d Power source I Current value Ip Current peak t time TP Time until current value reaches zero peak

Claims

Having an image recording layer on a support,
The image recording layer contains an alkali-soluble resin, an infrared absorber having a weight average molecular weight of 4,000 or more, and an onium salt compound,
Original planographic printing plate.
The lithographic printing plate precursor according to claim 1, wherein the infrared absorber has an acidic group.
The lithographic printing plate precursor according to claim 1 or 2, wherein the infrared absorbing agent includes a dye structure that absorbs infrared rays and a polymer structure.
The lithographic printing plate precursor according to claim 3, wherein the polymer structure includes a phenol resin structure.
The lithographic printing plate precursor according to any one of claims 1 to 4, wherein the image recording layer has an upper layer and a lower layer.
The lithographic printing plate according to any one of claims 1 to 5, wherein the onium salt compound is at least one compound selected from the group consisting of a quaternary ammonium salt compound and a sulfonium salt compound. Original version.
The alkali-soluble resin contains at least one resin selected from the group consisting of acetal resin, phenol resin, acrylic resin, and resin having urea bond, urethane bond or amide bond in the main chain. Item 10. The planographic printing plate precursor according to any one of items 6.
The lithographic printing plate according to any one of claims 1 to 7, wherein the alkali-soluble resin has a structural unit represented by the following formula 1 and a structural unit having a phenolic hydroxyl group in a side chain. Original version.

In Formula 1, R represents an alkyl group or an aryl group.
The lithographic printing plate precursor according to any one of claims 1 to 8, which is a lithographic printing plate precursor for non-silicate development.
A step of imagewise exposing the lithographic printing plate precursor according to any one of claims 1 to 9 using an infrared laser;
Developing with an alkali developer having a pH of 9 or higher containing no silicate compound,
A method for producing a lithographic printing plate, comprising:
The step of controlling the liquid activity of the alkaline developer by measuring the conductivity of the alkaline developer, adjusting the conductivity by adding a replenisher according to the measured value, and adjusting it to the target conductivity. The method for producing a lithographic printing plate according to claim 10.