JP2021189319A - On-machine development type planographic printing original plate, manufacturing method of planographic printing plate, as well as, planographic printing method - Google Patents

Abstract

To provide an on-machine development type planographic printing plate original plate that suppresses degradation of on-machine developability with time, and, can obtain a planographic printing plate excellent in printing resistance, a manufacturing method of a planographic printing plate using the planographic printing plate original plate, or a planographic printing method.SOLUTION: An on-machine development type planographic printing plate original plate comprises a support and an image recording layer formed on the support, and the image recording layer comprises a polymerizable compound A having an ethylenically unsaturated bond value of 5.0 mmol/g or larger, and a polymerizable compound B having two functions or lower and a molecular weight of 1,000 or smaller, a manufacturing method of a planographic printing plate using the planographic printing plate original plate, or a planographic printing method.SELECTED DRAWING: None

Description

The present disclosure relates to an on-machine development type lithographic printing plate original plate, a method for producing a lithographic printing plate, and a lithographic printing method.

Generally, a lithographic printing plate comprises a lipophilic image portion that receives ink in the printing process and a hydrophilic non-image portion that receives dampening water. In flat plate printing, the property that water and oil-based ink repel each other is used to make the oil-based image part of the flat plate printing plate an ink receiving part and the hydrophilic non-image part a dampening water receiving part (ink non-receptive part). This is a method in which a difference in the adhesiveness of ink is generated on the surface of a flat plate printing plate, the ink is inlaid only on the image portion, and then the ink is transferred to an object to be printed such as paper for printing.
In order to produce this lithographic printing plate, a lithographic printing plate original plate (PS plate) in which a lipophilic photosensitive resin layer (image recording layer) is provided on a hydrophilic support has been widely used. Normally, after the lithographic printing plate original plate is exposed through an original image such as a squirrel film, the portion that becomes the image portion of the image recording layer remains, and the other unnecessary image recording layer is an alkaline developer or organic. A lithographic printing plate is obtained by performing plate making by a method of dissolving and removing with a solvent to expose the surface of a hydrophilic support to form a non-image portion.

In addition, due to growing interest in the global environment, environmental issues related to waste liquids associated with wet treatments such as development treatments have been highlighted.
In response to the above environmental issues, simplification and non-processing of development or plate making are aimed at. As one of the simple manufacturing methods, a method called "on-machine development" is performed. That is, after the lithographic printing plate original plate is exposed, the conventional development is not performed, but the printing machine is mounted as it is, and the unnecessary portion of the image recording layer is removed at the initial stage of the normal printing process.
In the present disclosure, a lithographic printing plate original plate that can be used for such on-machine development is referred to as a "machine-developing lithographic printing plate original plate".

Examples of the conventional planographic printing plate original plate include those described in Patent Documents 1 to 4.
Patent Documents 1 to 4 describe an on-machine development type lithographic printing plate original plate having an image recording layer containing an oligomer having a polymerizable group and a trifunctional or higher functional acrylate compound.

Japanese Unexamined Patent Publication No. 2016-155271 Japanese Unexamined Patent Publication No. 2015-202586 Japanese Unexamined Patent Publication No. 2011-051350 Special Table 2018-508385 Gazette

The problem to be solved by one embodiment of the present disclosure is to provide an on-board development type lithographic printing plate original plate that suppresses deterioration of on-machine developability over time and can obtain a lithographic printing plate having excellent printing durability. It is to be.
An object to be solved by another embodiment of the present disclosure is to provide a method for producing a lithographic printing plate using the above-mentioned machine-developing lithographic printing plate original plate, or a method for lithographic printing.

The means for solving the above problems include the following aspects.
<1> It has a support and an image recording layer formed on the support.
The image recording layer contains a polymerizable compound A having an ethylenically unsaturated bond value of 5.0 mmol / g or more and a polymerizable compound B having a bifunctionality or less and a molecular weight of 1,000 or less. Print plate original plate.
<2> The on-machine development according to <1>, wherein the ratio of the content of the polymerizable compound B to the total amount of the polymerizable compound A and the polymerizable compound B in the image recording layer is 80% by mass or less. Type lithographic printing plate original plate.
<3> The machine-developed lithographic printing plate original plate according to <1> or <2>, wherein the polymerizable compound B is a methacrylate compound.
<4> The machine-developed lithographic printing plate original plate according to any one of <1> to <3>, wherein the polymerizable compound A is a compound represented by the following formula (I).
Equation (I): X- (Y) _n
In formula (I), X represents an n-valent organic group having a hydrogen-bonding group, Y represents a monovalent group having two or more ethylenically unsaturated groups, and n represents an integer of two or more. The molecular weight of X / (molecular weight of Y × n) is 1 or less.
<5> The group according to <4>, wherein the hydrogen-binding group in the polymerizable compound A contains at least one group selected from the group consisting of a urethane group, a urea group, an imide group, an amide group, and a sulfonamide group. On-board development type flat plate printing plate original plate.
<6> The machine according to any one of <1> to <5>, wherein the polymerizable compound A has at least one structure selected from the group consisting of an adduct structure, a biuret structure, and an isocyanurate structure. Top-developed lithographic printing plate original plate.

<7> The machine according to any one of <1> to <6>, wherein the polymerizable compound A has a structure represented by any of the following formulas (A-1) to (A-3). Top-developed lithographic printing plate original plate.

In the formula (A-1), ^RA1 represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and the wavy line portion represents a bond position with another structure.

<8> The machine-developed lithographic printing plate original plate according to any one of <1> to <7>, wherein the image recording layer further contains polyvinyl acetal.
<9> The machine-developed lithographic printing plate original plate according to <8>, wherein the polyvinyl acetal has a content of a structural unit having a hydroxyl group of 15 mol% or more with respect to all the structural units in the polyvinyl acetal.
<10> The machine-developed lithographic printing plate original plate according to any one of <1> to <9>, which has an outermost layer on the image recording layer.
<11> The machine-developed lithographic printing plate original plate according to <10>, wherein the outermost layer contains a hydrophobic polymer.
<12> The machine-developed lithographic printing plate original plate according to <10> or <11>, wherein the outermost layer contains a color-changing compound.
<13> The on-machine development type lithographic printing plate according to <12>, wherein the brightness change ΔL before and after the exposure is 2.0 or more when exposure is performed with infrared rays having a wavelength of 830 nm at an energy density of 110 mJ / cm ^2. Original version.
<14> The machine-developed lithographic printing plate original plate according to <12> or <13>, wherein the discolorable compound contains a compound that develops color due to infrared exposure.
<15> The machine-developed lithographic printing plate original plate according to any one of <12> to <14>, which contains a degradable compound in which the discolorable compound decomposes due to infrared exposure.
<16> The machine-developed lithographic printing plate original plate according to any one of <12> to <15>, wherein the discoloring compound is a cyanine dye.

<17> The machine-developed lithographic printing plate original plate according to any one of <12> to <16>, wherein the discolorable compound is a compound represented by the following formula 1-1.

In formula 1-1, R ¹ represents a group represented by any of the following formulas 2 to 4, and R ^{11 to} R ¹⁸ independently represent a hydrogen atom, a halogen atom, -R ^a , -OR ^b , and so on. Represents -SR ^c or -NR ^d R ^e , R ^{a to} R ^e each independently represent a hydrocarbon group, and A ₁ , A ₂ and a plurality of R _{11 to} R ₁₈ are linked to form a single ring or Polycycles may be formed, where A ₁ and A ₂ independently represent an oxygen atom, a sulfur atom, or a nitrogen atom, and n ₁₁ and n ₁₂ each independently represent an integer of 0 to 5. However, _{the total of n 11} and n ₁₂ is 2 or more, n ₁₃ and n ₁₄ independently represent 0 or 1, L represents an oxygen atom, a sulfur atom, or −NR ¹⁰ −, and R ¹⁰ Represents a hydrogen atom, an alkyl group, or an aryl group, and Za represents a counterion that neutralizes the charge.

In Formulas 2 to 4, R ²⁰ , R ³⁰ , R ⁴¹ and R ⁴² independently represent an alkyl group or an aryl group, Zb represents a counterion that neutralizes the charge, and the wavy line represents the above formula 1-. Represents a binding site with a group represented by L in 1.

<18> The machine-developed lithographic printing plate original plate according to <17>, wherein the discolorable compound is a compound represented by the following formula 1-2.

In formula 1-2, R ¹ represents a group represented by any of the above formulas 2 to 4, and R ^{19 to} R ²² are independently hydrogen atom, halogen atom, -R ^a , -OR ^b , respectively. -CN, -SR ^c, or represents ^-NR d ^{R e, R 23} and ^{R 24} each independently represent a hydrogen atom, or represents a -R ^a, R ^a ~R ^e are each independently a hydrocarbon Representing a group, R ¹⁹ and R ²⁰ , R ²¹ and R ²² , or R ²³ and R ²⁴ may be linked to form a monocyclic or polycyclic, where L is an oxygen atom, a sulfur atom, or a hydrogen atom. , -NR ^10- , where R ¹⁰ represents a hydrogen atom, an alkyl group, or an aryl group, and R ^{d1 to} R ^d4 , W ¹ and W ² may each independently have a substituent. Represents an alkyl group and Za represents a counterion that neutralizes the charge.

<19> The machine-developed lithographic printing plate according to any one of <17> or <18>, wherein the discolorable compound is a compound represented by any of the following formulas 1-3 to 1-7. Original version.

In formulas 1-3 to 1-7, R ¹ represents a group represented by any of the above formulas 2 to 4, and R ^{19 to} R ²² are independently hydrogen atom, halogen atom, and −R ^a. , -OR ^b , -CN, -SR ^c , or -NR ^d R ^e , and R ²⁵ and R ^{26 independently represent a} hydrogen atom, a halogen atom, or -R a, and R ^{a to} R ^e. Represent each independently as a hydrocarbon group, and R ¹⁹ and R ²⁰ , R ²¹ and R ²² , or R ²⁵ and R ²⁶ may be linked to form a monocyclic or polycyclic, where L is. Represents an oxygen atom, a sulfur atom, or -NR ^10- , R ¹⁰ represents a hydrogen atom, an alkyl group, or an aryl group, and R ^{d1 to} R ^d4 , W ¹ and W ² are independent substituents. Represents an alkyl group which may have, and Za represents a counterion that neutralizes the charge.

^{<20> W 1} and W ² in the above formulas 1-2 to 1-7 are alkyl groups each independently having a substituent, and as the above-mentioned substituents,-(OCH ₂ CH ₂ )-, The machine-developed flat plate printing plate original plate according to <18> or <19>, which is a sulfo group, a salt of a sulfo group, a carboxy group, or a group having at least a salt of a carboxy group.
<21> The image recording layer further contains a polymerization initiator and contains
The on-machine development type lithographic printing plate original plate according to any one of <1> to <20>, wherein the polymerization initiator contains an electron donating type polymerization initiator and an electron accepting type polymerization initiator.
<22> The machine-developed lithographic printing plate original plate according to <21>, wherein the polymerization initiator contains a compound in which the electron donating type polymerization initiator and the electron accepting type polymerization initiator form an anti-salt.

<23> The machine-developed lithographic printing plate original plate according to <21>, wherein the electron-accepting polymerization initiator contains a compound represented by the following formula (II).

In formula (II), X represents a halogen atom and R ³ represents an aryl group.

<24> The image recording layer contains an infrared absorber and contains an infrared absorber.
HOMO of the infrared absorber-The machine-developed lithographic printing plate original plate according to any one of <21> to <23>, wherein the HOMO value of the electron donating type polymerization initiator is 0.70 eV or less.
<25> Any one of <21> to <24> in which the image recording layer contains an infrared absorber and the LUMO value of the electron-accepting polymerization initiator-LUMO of the infrared absorber is 0.70 eV or less. On-board development type lithographic printing plate original plate described in 1.

<26> The support has an aluminum plate and an aluminum anodized film arranged on the aluminum plate.
The anodic oxide film is located closer to the image recording layer than the aluminum plate.
The anodic oxide film has micropores extending in the depth direction from the surface on the image recording layer side.
The machine-developed lithographic printing plate original plate according to any one of <1> to <25>, wherein the average diameter of the micropores on the surface of the anodic oxide film is more than 10 nm and 100 nm or less.
<27> The micropore communicates with the large-diameter hole extending from the surface of the anodic oxide film to a depth of 10 nm to 1,000 nm and the bottom of the large-diameter hole, and has a depth of 20 nm to 2 from the communication position. It consists of a small-diameter hole that extends to a position of 000 nm.
The average diameter of the large-diameter hole portion on the surface of the anodic oxide film is 15 nm to 100 nm.
The on-machine development type lithographic printing plate original plate according to <26>, wherein the average diameter of the small diameter hole portion at the communication position is 13 nm or less.

<28> A step of exposing the machine-developed lithographic printing plate original plate according to any one of <1> to <27> to an image.
A method for producing a lithographic printing plate, comprising a step of supplying at least one selected from the group consisting of printing ink and dampening water on a printing machine to remove an image recording layer in a non-image area.
<29> A step of exposing the machine-developed lithographic printing plate original plate according to any one of <1> to <27> to an image.
A process of supplying at least one selected from the group consisting of printing ink and dampening water on a printing machine to remove the image recording layer in the non-image area to produce a lithographic printing plate.
Including the process of printing with the obtained lithographic printing plate,
Planographic printing method.

According to one embodiment of the present disclosure, it is possible to provide an on-board development type lithographic printing plate original plate capable of suppressing a decrease in on-machine developability over time and obtaining a lithographic printing plate having excellent printing resistance. ..
Further, according to another embodiment of the present disclosure, it is possible to provide a method for producing a lithographic printing plate using the above-mentioned machine-developing lithographic printing plate original plate, or a lithographic printing method.

It is a schematic sectional view of one Embodiment of a support. FIG. 3 is a schematic cross-sectional view of another embodiment of the support. It is a schematic diagram of the anodizing treatment apparatus used for the anodizing treatment in the manufacturing method of the support which has an anodic oxide film.

The contents of the present disclosure will be described in detail below. The description of the constituents described below may be based on the representative embodiments of the present disclosure, but the present disclosure is not limited to such embodiments.
In the present disclosure, "~" indicating a numerical range is used to mean that the numerical values described before and after the numerical range are included as the lower limit value and the upper limit value.
In the numerical range described stepwise in the present disclosure, the upper limit value or the lower limit value described in one numerical range may be replaced with the upper limit value or the lower limit value of the numerical range described in another stepwise description. .. 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 notation of a group (atomic group) in the present disclosure, the notation that does not describe substitution or non-substitution includes those having no substituent as well as 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 in a concept that includes both acrylic and methacrylic, and "(meth) acryloyl" is a term that is used as a concept that includes both acryloyl and methacrylic. be.
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 in an independent process but also in the case where it cannot be clearly distinguished from other processes. Is done.
Further, in the present disclosure, "% by mass" and "% by weight" are synonymous, and "parts by mass" and "parts by weight" are synonymous.
Further, in the present disclosure, a combination of two or more preferred embodiments is a more preferred embodiment.
Further, for the weight average molecular weight (Mw) and the number average molecular weight (Mn) in the present disclosure, unless otherwise specified, columns of TSKgel GMHxL, TSKgel G4000HxL, and TSKgel G2000HxL (all trade names manufactured by Toso Co., Ltd.) are used. The molecular weight is detected by the solvent THF (tetrahydrofuran) and the differential refractometer by the gel permeation chromatography (GPC) analyzer and converted using polystyrene as the standard substance.
In the present disclosure, the term "lithographic printing plate original plate" includes not only a lithographic printing plate original plate but also a discarded plate original plate. Further, the term "lithographic printing plate" includes not only a lithographic printing plate produced by subjecting a lithographic printing plate original plate through operations such as exposure and development, but also a discarded plate, if necessary. In the case of a discarded original plate, exposure and development operations are not always necessary. The discarded plate is a lithographic printing plate original plate for attaching to an unused plate cylinder, for example, when printing a part of the paper surface in a single color or two colors in color newspaper printing.
In the present disclosure, "excellent in printing resistance" means that the number of printable sheets of a lithographic printing plate is large, and the printing resistance when UV ink is used as the ink for printing is hereinafter referred to as "UV". Also called "print resistance".

≪In-machine development type lithographic printing plate original plate≫
The on-machine development type lithographic printing plate original plate (hereinafter, also simply referred to as “lithographic printing plate original plate”) according to the present disclosure has a support and an image recording layer formed on the support, and the image recording layer. However, it contains a polymerizable compound A having an ethylenically unsaturated bond value of 5.0 mmol / g or more, and a polymerizable compound B having a bifunctionality or less and a molecular weight of 1,000 or less.
Further, the lithographic printing plate original plate according to the present disclosure is preferably a negative type lithographic printing plate original plate.

In the machine-developed lithographic printing plate original plate as described in Patent Documents 1 to 4, since the functional group density of the polymerizable group due to the polymerizable compound in the image recording layer is high, the lithographic printing plate has excellent printing resistance. Is considered to be obtained. On the other hand, when such an on-machine development type lithographic printing plate original plate is used after being stored after production, the on-machine developability may be lower than that immediately after production. This is considered to be due to dark polymerization in the image recording layer during storage.
According to the lithographic printing plate original plate according to the present disclosure, a lithographic printing plate having excellent printing durability can be obtained while suppressing deterioration of on-machine developability over time.
The detailed mechanism by which the above effect is obtained is unknown, but it is presumed as follows.
In the lithographic printing plate original plate according to the present disclosure, in the image recording layer, for example, a polymerizable compound A such as a polyfunctional oligomer having about 10 functional groups, and a monofunctional or bifunctional, low molecular weight polymerizable compound are used. B is used. By using the polymerizable compound B, the functional group density of the polymerizable group in the image recording layer is lowered, and the dark polymerization caused by the high functional group density is suppressed, so that the on-machine developability is lowered with time. Is considered to be less likely to occur. Further, since the polymerizable compound A having a large number of functional groups is used and the polymerizable compound B also contributes to the polymerization reaction in the image recording layer, it is considered that excellent printing resistance can be maintained. Be done.

In the image recording layer in the present disclosure, the ratio of the content of the polymerizable compound B to the total amount of the polymerizable compound A and the polymerizable compound B (hereinafter, also referred to as the ratio [B / (A + B)]) is 80% by mass or less. Is preferable.
The ratio [B / (A + B)] may be 70% by mass or less, preferably 60% by mass or less, more preferably 55% by mass or less, further preferably 50% by mass or less, and particularly preferably 45% by mass or less.
The lower limit of the above ratio [B / (A + B)] is more than 0% by mass, preferably 1% by mass or more, more preferably 5% by mass or more, further preferably 10% by mass or more, and particularly preferably 15% by mass or more. preferable.
The ratio [B / (A + B)] is preferably 5% by mass to 70% by mass, more preferably 10% by mass to 60% by mass, and even more preferably 15% by mass to 45% by mass.

Next, the details of each constituent requirement in the lithographic printing plate original plate according to the present disclosure will be described.

<Image recording layer>
The lithographic printing plate original plate according to the present disclosure has an image recording layer on a support.
The image recording layer in the present disclosure has a polymerizable compound A and a polymerizable compound B.
The image recording layer in the present disclosure preferably contains, for example, a polymerization initiator, an infrared absorber, and other components in addition to the polymerizable compound A and the polymerizable compound B.
The image recording layer in the present disclosure is preferably a negative image recording layer, and more preferably a water-soluble or water-dispersible negative image recording layer.
From the viewpoint of on-machine developability, the unexposed portion of the image recording layer in the present disclosure is preferably removable with at least one of dampening water and printing ink.

Hereinafter, the details of each component contained in the image recording layer will be described.

[Polymerizable compound A]
The polymerizable compound A is a compound having an ethylenically unsaturated bond value (also referred to as “C = C value”) of 5.0 mmol / g or more.
When the C = C value of the polymerizable compound A is 5.0 mmol / g or more, the curing reaction of the image recording layer by exposure is promoted, and a lithographic printing plate having excellent printing resistance is formed.
The C = C value of the polymerizable compound A is preferably 5.5 mmol / g or more, and more preferably 6.0 mmol / g or more.
The upper limit of the C = C value of the polymerizable compound A is, for example, 10.0 mmol / g or less, and more preferably 8.5 mmol / g or less.

Here, the ethylenically unsaturated bond value of a compound having an ethylenically unsaturated bond, such as the polymerizable compound A and the polymerizable compound B described later, is determined by the following method.
First, for a compound having a predetermined sample amount (for example, 0.2 g), the structure of the compound is specified by using, for example, pyrolysis GC / MS, FT-IR, NMR, TOF-SIMS, etc., and ethylenically unsaturated. Determine the total amount (mmol) of the group. The ethylenically unsaturated bond value of a compound is calculated by dividing the total amount (mmol) of the determined ethylenically unsaturated groups by the sample amount (g) of the compound.

The polymerizable compound A is preferably a compound represented by the following formula (I) from the viewpoint of satisfying the above C = C value.
Equation (I): X- (Y) _n
In formula (I), X represents an n-valent organic group having a hydrogen-bonding group, Y represents a monovalent group having two or more ethylenically unsaturated groups, and n represents an integer of two or more. The molecular weight of X / (molecular weight of Y × n) is 1 or less.

The hydrogen-bonding group in X of the formula (I) is not particularly limited as long as it is a hydrogen-bondable group, and whether it is a hydrogen-bond-donating group or a hydrogen-bond-accepting group, both of them. May be.
Examples of the hydrogen-binding group include a hydroxy group, a carboxy group, an amino group, a carbonyl group, a sulfonyl group, a urethane group, a urea group, an imide group, an amide group, a sulfonamide group and the like.
Among them, the hydrogen-binding group is at least one group selected from the group consisting of a urethane group, a urea group, an imide group, an amide group, and a sulfonamide group from the viewpoint of on-machine developability and print resistance. Is more preferable, and it is more preferable to contain at least one group selected from the group consisting of a urethane group, a urea group, an imide group, and an amide group, and more preferably than a group consisting of a urethane group, a urea group, and an imide group. It is more preferable that it is at least one selected group, and it is particularly preferable that it contains at least one group selected from the group consisting of a urethane group and a urea group.

It is preferable that X in the formula (I) is an organic group having no ethylenically unsaturated bond.
Further, X in the formula (I) is a monovalent to n-valent aliphatic hydrocarbon group, a monovalent to n-valent aromatic hydrocarbon group, a urethane bond, or a urea from the viewpoint of on-machine developability and print resistance. It is preferably a group combining two or more structures selected from the group consisting of a bond, a biuret bond, and an allophanate bond, a monovalent to n-valent aliphatic hydrocarbon group, and a monovalent to n-valent aromatic group. It is more preferable that the group is a combination of two or more structures selected from the group consisting of a hydrocarbon group, a urethane bond, a urea bond, and a biuret bond.

X in the formula (I) is a multifunctional compound in which a polyfunctional isocyanate compound is abundant (including an adduct of a polyfunctional alcohol compound such as a trimethylolpropane adduct) from the viewpoint of on-machine developability and print resistance. It is preferable that the group is a group obtained by removing the terminal isocyanate group from the group, and is a group obtained by removing the terminal isocyanate group from a multifunctional body (including an adduct body of a polyfunctional alcohol compound) in which the amount of the bifunctional isocyanate compound is increased. Is more preferable, and it is particularly preferable that the group is obtained by removing the terminal isocyanate group from the mulched product (including the adduct body of the polyfunctional alcohol compound) in which the amount of hexamethylene diisocyanate is increased.

The molecular weight of X in the formula (I) is preferably 100 to 1,000, more preferably 150 to 800, and particularly preferably 150 to 500, from the viewpoint of on-machine developability and print resistance.

The ethylenically unsaturated group in Y of the formula (I) is not particularly limited, and from the viewpoint of reactivity, on-machine developability, and print resistance, a vinylphenyl group (styryl group), a vinyl ester group, a vinyl ether group, More preferably, it is at least one group selected from the group consisting of an allyl group, a (meth) acryloxy group, and a (meth) acrylamide group, a vinylphenyl group (styryl group), a (meth) acryloxy group, and ( It is more preferably at least one group selected from the group consisting of a (meth) acrylamide group, and particularly preferably a (meth) acryloxy group.
That is, the ethylenically unsaturated group in Y of the formula (I) preferably contains a (meth) acryloxy group from the viewpoint of on-machine developability and print resistance.

Y in the formula (I) is preferably a group having three or more (meth) acryloxy groups, more preferably a group having five or more (meth) acryloxy groups, and five or more twelve. It is more preferable that the group has the following (meth) acryloxy groups.

Y in the formula (I) may have a structure represented by the following formula (Y-1) or the formula (Y-2) from the viewpoint of on-machine developability and print resistance.

In the formula (Y-1) and the formula (Y-2), R independently represents an acrylic group or a methacrylic group, and the wavy line portion represents a bonding position with another structure.

In the formula (Y-1) or the formula (Y-2), it is preferable that R is all the same group.
Further, in the formula (Y-1) or the formula (Y-2), R is preferably an acrylic group.

Further, it is preferable that the n Ys in the formula (I) are all the same group.

The molecular weight of Y in the formula (I) is preferably 200 or more and 1,000 or less, and more preferably 250 or more and 800 or less, from the viewpoint of on-machine developability and print resistance.

N in the formula (I) is an integer of 2 or more, and is more preferably 2 to 3 from the viewpoint of on-machine developability and print resistance.

The molecular weight of X / (molecular weight of Y × n) is 1 or less, preferably 0.01 to 0.8 from the viewpoint of on-machine developability and printing resistance, and 0.1 to 0.5. It is more preferable to have.

As described above, the structure of the polymerizable compound A is preferably a structure in which the terminal isocyanate group of the multifunctionalized isocyanate compound (including the adduct) is sealed with a compound having an ethylenically unsaturated group. Be done. Among them, as the multi-functional isocyanate compound multiplier, a bifunctional isocyanate compound multiplier is preferable.

Further, from the viewpoint of on-machine developability and print resistance, the polymerizable compound A is a polyfunctional compound having a hydroxy group (also referred to as a hydroxyl group) at the end of the terminal isocyanate group of the multi-layered product in which the polyfunctional isocyanate compound is increased in quantity. It is preferably a compound obtained by reacting an ethylenically unsaturated compound, and a polypoly having a hydroxy group at the terminal isocyanate group of a multi-layer (including an adduct of a polyfunctional alcohol compound) in which a large amount of a bifunctional isocyanate compound is added. It is more preferable that the compound is formed by reacting a functional ethylenically unsaturated compound, and has a hydroxy group at the terminal isocyanate group of a multimer (including an adduct of a polyfunctional alcohol compound) in which hexamethylene diisocyanate is abundant. It is particularly preferable that the compound is obtained by reacting a polyfunctional ethylenically unsaturated compound.

The polyfunctional isocyanate compound is not particularly limited, and known compounds can be used, and may be an aliphatic polyfunctional isocyanate compound or an aromatic polyfunctional isocyanate compound.
Specific examples of the polyfunctional isocyanate compound include 1,3-bis (isocyanatomethyl) cyclohexane, isophorone diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, and 1,3-. Cyclopentane diisocyanate, 9H-fluorene-2,7-diisocyanate, 9H-fluoren-9-on-2,7-diisocyanate, 4,4'-diphenylmethane diisocyanate, 1,3-phenylenediisocyanate, tolylen-2 , 4-Diisocyanate, Trilen-2,6-Diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, 2,2-bis (4-isocyanatophenyl) hexafluoropropane, 1,5-di Isocyanatonaphthalene, dimers of these polyisocyanates, trimmers (isocyanurate bonds) and the like are preferably mentioned. Further, a biuret compound obtained by reacting the above polyisocyanate compound with a known amine compound may be used.
The polyfunctional ethylenically unsaturated compound having a hydroxy group is preferably a trifunctional or higher functional ethylenically unsaturated compound having a hydroxy group, and is a pentafunctional or higher functional ethylenically unsaturated compound having a hydroxy group. Is more preferable. The polyfunctional ethylenically unsaturated compound having a hydroxy group is preferably a polyfunctional (meth) acrylate compound having a hydroxy group.

From the viewpoint of on-machine developability and print resistance, the polymerizable compound A preferably has at least one structure selected from the group consisting of an adduct structure, a biuret structure, and an isocyanurate structure, and is preferably trimethylpropan adduct. It is more preferable to have at least one structure selected from the group consisting of a structure, a biuret structure, and an isocyanurate structure, and it is particularly preferable to have a trimethylolpropane adduct structure.

From the viewpoint of on-machine developability and print resistance, the polymerizable compound A preferably has a structure represented by any of the following formulas (A-1) to (A-3), and preferably has the following formula (A). It is more preferable to have the structure represented by -1).

In the formula (A-1), ^RA1 represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and the wavy line portion represents a bond position with another structure.

R ^A1 in the formula (A1), from the viewpoint of on-press development property and printing durability, a hydrogen atom, or preferably an alkyl group having 1 to 4 carbon atoms, an alkyl group having 1 to 3 carbon atoms It is more preferably present, more preferably a methyl group or an ethyl group, and particularly preferably an ethyl group.

The polymerizable compound A is preferably a (meth) acrylate compound having a urethane group, that is, a urethane (meth) acrylate oligomer from the viewpoint of on-machine developability and print resistance.

The polymerizable compound A may be an oligomer having a polyester bond (hereinafter, also referred to as a polyester (meth) acrylate oligomer) as long as the C = C value is 5.0 mmol / g or more, or has an epoxy residue. It may be an oligomer (hereinafter, also referred to as an epoxy (meth) acrylate oligomer).
Here, the epoxy residue in the present disclosure refers to a structure formed by an epoxy group, and means, for example, a structure similar to a structure obtained by a reaction between an acid group (carboxylic acid group or the like) and an epoxy group.

The number of ethylenically unsaturated groups in the polyester (meth) acrylate oligomer which is the polymerizable compound A is preferably 3 or more, and more preferably 6 or more.
The upper limit of the number of ethylenically unsaturated groups in the polyester (meth) acrylate oligomer is, for example, 15.

As the epoxy (meth) acrylate oligomer which is the polymerizable compound A, a compound containing a hydroxy group in the compound is preferable.
The number of ethylenically unsaturated groups in the epoxy (meth) acrylate oligomer is preferably 2 to 6, and more preferably 2 to 3.
The epoxy (meth) acrylate oligomer can be obtained, for example, by reacting a compound having an epoxy group with acrylic acid.

The molecular weight of the polymerizable compound A (in the case of having a molecular weight distribution, the weight average molecular weight) may be more than 1,000, preferably 1,100 to 10,000, and more preferably 1,100 to 5,000. preferable.

As the polymerizable compound A, a synthetic product or a commercially available product may be used.
Specific examples of the polymerizable compound A include, for example, the following commercially available products, but the polymerizable compound A used in the present disclosure is not limited thereto. In addition, the number of functional groups (or the average number of functional groups) of the ethylenically unsaturated group and the C = C value are shown in parentheses.
That is, as specific examples of the polymerizable compound A, U-10HA (number of functional groups: 10, C = C value: 8 mmol / g) and U-15HA (number of functional groups: 15, C =) of Shin Nakamura Chemical Industry Co., Ltd. C value: 6 mmol / g), UA-510H of Kyoeisha Chemical Co., Ltd. (number of functional groups: 10, C = C value: 8 mmol / g), KRM8452 of Dycel Ornex Co., Ltd. (number of functional groups: 10, C = C) Urethane (meth) acrylates such as CN8885NS (number of functional groups: 9, C = C value: 6 mmol / g), CN9013NS (number of functional groups: 9, C = C value: 6 mmol / g), Sartmer Co., Ltd. Examples include oligomers.
Specific examples of the polymerizable compound A include NK Oligo EA-7420 / PGMAc (number of functional groups: 10 to 15, C = C value: 5 mmol / g) of Shin Nakamura Chemical Industry Co., Ltd., and CN153 (C) of Sartmer Co., Ltd. = C value: 5 mmol / g) or the like, and examples thereof include epoxy (meth) acrylate oligomers.
Further, specific examples of the polymerizable compound A include polyester (meth) acrylate oligomers such as CN2267 (C = C value: 5 mmol / g) manufactured by Sartmer.

The content of the polymerizable compound A is preferably 10% by mass to 90% by mass, and 15% by mass to 85% by mass, based on the total mass of the image recording layer, from the viewpoint of on-machine developability and print resistance. %, More preferably 15% by mass to 60% by mass.

[Polymerizable compound B]
The polymerizable compound B is a compound having a bifunctionality or less and a molecular weight of 1,000 or less.
The polymerizable group of the polymerizable compound B is preferably an ethylenically unsaturated group, and the preferred embodiment of the ethylenically unsaturated group is the same as that of the ethylenically unsaturated group in the polymerizable compound A.
Further, the polymerizable compound B may be a bifunctional or less, that is, a monofunctional or bifunctional polymerizable compound, but is a bifunctional polymerizable compound from the viewpoint of suppressing a decrease in on-machine developability. Is preferable.

The polymerizable compound B is preferably a methacrylate compound, that is, a compound having a methacrylate group, from the viewpoint of on-machine developability and printing resistance.

The polymerizable compound B preferably contains an alkyleneoxy structure or a urethane bond from the viewpoint of on-machine developability.

The molecular weight (weight average molecular weight in the case of having a molecular weight distribution) of the polymerizable compound B is preferably 50 to 1,000, more preferably 200 to 900, and more preferably 250 to 800. More preferred.

Specific examples of the polymerizable compound B are given below, but the polymerizable compound B used in the present disclosure is not limited thereto. In the compound of the following (2), for example, n + m = 10.

As the polymerizable compound B, commercially available products shown below may be used, but the polymerizable compound B used in the present disclosure is not limited thereto.
That is, specific examples of the polymerizable compound B include BPE-80N (compound of (1) above), BPE-100, BPE-200, BPE-500 of Shin-Nakamura Chemical Industry Co., Ltd., and CN104 of Sartmer (above). Examples thereof include ethoxylated bisphenol A dimethacrylate (compound of (1)) and the like.
Specific examples of the polymerizable compound B include A-BPE-10 (compound of (2) above) manufactured by Shin Nakamura Chemical Industry Co., Ltd., and ethoxylated bisphenol A diacrylates such as A-BPE-4. ..
Further, specific examples of the polymerizable compound B include bifunctional methacrylates such as FST 510 manufactured by AZ Electronics.

Here, the above-mentioned "FST 510" is a reaction product of 1 mol of 2,2,4-trimethylhexamethylene diisocyanate and 2 mol of hydroxyethyl methacrylate, and is a solution of the above compound (3) in an 82% by mass of methyl ethyl ketone. be.

The content of the polymerizable compound B is preferably 1% by mass to 60% by mass and 5% by mass to 55% by mass with respect to the total mass of the image recording layer from the viewpoint of on-machine developability and print resistance. %, More preferably 5% by mass to 50% by mass.

[Polymerization initiator]
The image recording layer in the present disclosure contains a polymerization initiator.
The polymerization initiator preferably contains an electron-accepting polymerization initiator, and more preferably contains an electron-accepting polymerization initiator and an electron-donating polymerization initiator.

[Electron-accepting polymerization initiator]
The image recording layer preferably contains an electron-accepting polymerization initiator as the polymerization initiator.
The electron-accepting polymerization initiator is a compound that generates a polymerization initiator such as a radical by accepting one electron by electron transfer between molecules when the electron of the infrared absorber is excited by infrared exposure.
The electron-accepting polymerization initiator is a compound that generates a polymerization initiator such as a radical or a cation by energy of light, heat, or both, and is a known thermal polymerization initiator, a compound having a small bond of bond dissociation energy, and the like. A photopolymerization initiator or the like can be appropriately selected and used. As the electron-accepting polymerization initiator, a radical polymerization initiator is preferable, and an onium salt compound is more preferable.
The electron-accepting polymerization initiator is preferably an infrared photosensitive polymerization initiator.

Among the electron-accepting polymerization initiators, oxime ester compounds and onium salt compounds are preferable from the viewpoint of curability. Among them, from the viewpoint of printing resistance, an iodonium salt compound, a sulfonium salt compound, or an azinium salt compound is preferable, an iodonium salt compound or a sulfonium salt compound is more preferable, and an iodonium salt compound is particularly preferable.
Specific examples of these compounds are shown below, but the present disclosure is not limited thereto.

As an example of the iodonium salt compound, a diaryliodonium salt compound is preferable, a diphenyliodonium salt compound substituted with an electron donating group, for example, an alkyl group or an alkoxyl group is more preferable, and an asymmetric diphenyliodonium salt compound is preferable. .. Specific examples include diphenyliodonium = hexafluorophosphate, 4-methoxyphenyl-4- (2-methylpropyl) phenyliodonium = hexafluorophosphate, 4- (2-methylpropyl) phenyl-p-tolyliodonium = hexa. Fluorophosphate, 4-hexyloxyphenyl-2,4,6-trimethoxyphenyliodonium = hexafluorophosphate, 4-hexyloxyphenyl-2,4-diethoxyphenyliodonium = tetrafluoroborate, 4-octyloxy Phenyl-2,4,6-trimethoxyphenyliodonium = 1-perfluorobutanesulfonate, 4-octyloxyphenyl-2,4,6-trimethoxyphenyliodonium = hexafluorophosphart, bis (4-t-butylphenyl) ) Iodonium = hexafluorophosphart can be mentioned.

Examples of the counter anion of the iodonium salt compound and the sulfonium salt compound include sulfonate anion, carboxylate anion, tetrafluoroborate anion, hexafluorophosphate anion, p-toluene sulfonate anion, tosylate anion, sulfonamide anion or sulfonimide. Anions are mentioned.
Of these, sulfonamide anions or sulfonimide anions are preferable, and sulfonamide anions are more preferable.
As the sulfonamide anion, an aryl sulfonamide anion is preferable.
Further, as the sulfoneimide anion, a bisaryl sulfoneimide anion is preferable.
Specific examples of the sulfonamide anion or the sulfonamide anion include the compounds described in paragraph 0034 of WO 2019/013268.

Further, the electron-accepting polymerization initiator is preferably a compound represented by any of the following formulas (II) and (III) from the viewpoint of developability and UV printing resistance in the obtained lithographic printing plate. , Particularly the compound represented by the formula (II) is preferable.

In formulas (II) and (III), X represents a halogen atom, and R ³ , R ⁴ and R ⁵ each independently represent a monovalent hydrocarbon group having 1 to 20 carbon atoms.
In formula (II), it is preferable that X represents a halogen atom and R ^{3 represents an aryl group.}

Specific examples of the X in the formulas (II) and (III) include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom. Of these, a chlorine atom or a bromine atom is preferable because it has excellent sensitivity, and a bromine atom is particularly preferable.
Further, in the formulas (II) and (III), R ³ , R ⁴ and R ⁵ are preferably aryl groups independently of each other, and above all, from the viewpoint of excellent balance between sensitivity and storage stability, amides are used. Aryl groups substituted with groups are preferred.

Among the electron-accepting polymerization initiators, the compound represented by the formula (IV) is particularly preferable.

In formula (IV), R ⁴ and R ⁵ each independently represent a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. p and q each independently represent an integer from 1 to 5. However, p + q = 2 to 6.

Specific examples of the electron-accepting polymerization initiator represented by any of the above formulas (II) to (IV) include compounds represented by the following formulas, but the present disclosure is not limited thereto. No.

The minimum unoccupied molecular orbital (LUMO) of the electron-accepting polymerization initiator is preferably −3.00 eV or less, and more preferably −3.02 eV or less, from the viewpoint of improving sensitivity and making plate skipping less likely to occur. preferable.
The lower limit is preferably -3.80 eV or more, and more preferably -3.50 eV or more.
In the present disclosure, the lowest unoccupied molecular orbital (LUMO) and the highest occupied molecular orbital (HOMO) described later are calculated by the following method.
First, when the compound to be calculated has a counterion that is not the main structure forming HOMO or LUMO, the counterion may be ignored.
Using the quantum chemistry calculation software Gaussian09, the structure optimization is DFT (B3L).
YP / 6-31G (d)).
The MO (molecular orbital) energy calculation is performed by DFT (B3LYP / 6-31 + G (d, p) / CPCM (solvent = methanol)) with the structure obtained by the above structural optimization.
The MO energy Ebare (unit: hartree) obtained by the above MO energy calculation is converted into Escaled (unit: eV) used as the values of HOMO and LUMO in the present disclosure by the following formula.
Escaled = 0.823168 x 27.2114 x Ebare-1.07634
Note that 27.2114 is simply a coefficient for converting hartree to eV, 0.823168 and −1.07634 are adjustment coefficients, and the calculated values of HOMO and LUMO of the compound to be calculated are actually measured. Determine to suit.

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

The content of the electron-accepting polymerization initiator is preferably 0.1% by mass to 50% by mass, more preferably 0.5% by mass to 30% by mass, based on the total mass of the image recording layer. , 0.8% by mass to 20% by mass is particularly preferable.

[Electron-donated polymerization initiator (polymerization aid)]
The image recording layer in the present disclosure preferably contains an electron donating type polymerization initiator (also referred to as a polymerization aid) as a polymerization initiator.
The electron donating type polymerization initiator is a radical by donating one electron by intermolecular electron transfer to the orbital where one electron is missing from the infrared absorber when the electron of the infrared absorber is excited or moved intramolecularly by infrared exposure. It is a compound that generates a polymerization initiator such as.
The electron donating type polymerization initiator is preferably an electron donating type radical polymerization initiator.

From the viewpoint of printing resistance, the image recording layer preferably contains a borate compound as an electron donating type polymerization initiator.
The borate compound is preferably a tetraarylborate compound or a monoalkyltriarylborate compound, and more preferably a tetraarylborate compound, from the viewpoint of print resistance.
The counter cation contained in the borate compound is not particularly limited, but is preferably an alkali metal ion or a tetraalkylammonium ion, and more preferably a sodium ion, a potassium ion, or a tetrabutylammonium ion.
Further, the counter cation of the borate compound may be a cationic polymethine dye described as an infrared absorber in the present disclosure. For example, the above borate compound may be used as a counter cation of a cyanine pigment.

Specific examples of the borate compound include sodium tetraphenylborate.

B-1 to B-9 are shown below as preferred specific examples of the electron donating type polymerization initiator, but it goes without saying that the present invention is not limited to these. Further, in the following chemical formula, Ph represents a phenyl group and Bu represents an n-butyl group.

Further, the maximum occupied molecular orbital (HOMO) of the electron donating type polymerization initiator is preferably −6.00 eV or more, and preferably −5.95 eV or more, from the viewpoint of improving sensitivity and making it difficult for plate skipping to occur. More preferably, it is more preferably −5.93 eV or more.
The upper limit is preferably −5.00 eV or less, and more preferably −5.40 eV or less.

As the electron donating type polymerization initiator, only one kind may be used, or two or more kinds may be used in combination.

The content of the electron donating type polymerization initiator is preferably 0.01% by mass to 30% by mass, preferably 0.05% by mass, based on the total mass of the image recording layer from the viewpoint of sensitivity and printing resistance. It is more preferably ~ 25% by mass, and even more preferably 0.1% by mass to 20% by mass.

The polymerization initiator may be a compound in which the electron donating type polymerization initiator and the electron accepting type polymerization initiator form an anti-salt.
For example, it is preferable that the anion in the electron-donating polymerization initiator and the cation in the electron-accepting polymerization initiator form a counter-salt, and the electron-accepting polymerization initiator and the electron-donating polymerization initiator are preferable. More preferably, it is a compound in which a cation having an electron-accepting polymerization initiator structure and an anion having an electron-donating polymerization initiator structure form a salt. Specifically, it is preferably a compound in which an onium cation and a borate anion form an anti-salt, and more preferably a compound in which an iodonium cation or a sulfonium cation and a borate anion form an anti-salt. , A compound formed by forming a salt with a diaryliodonium cation or a triarylsulfonium cation and a tetraarylborate anion is particularly preferable.
Preferred embodiments of the anion in the electron-donating polymerization initiator and the cation in the electron-accepting polymerization initiator include the anion in the electron-donating polymerization initiator described above and the cation in the electron-accepting polymerization initiator described above. It is the same as the embodiment.
When the image recording layer contains an anion which is an electron donating type polymerization initiator and a cation which is an electron accepting type polymerization initiator (that is, when it contains the compound forming the above salt), the image recording layer. Shall include an electron-accepting polymerization initiator and the electron-donating polymerization initiator.
Further, the compound in which the electron donating type polymerization initiator and the electron accepting type polymerization initiator form an anti-salt may be used as an electron donating type polymerization initiator or as an electron accepting type polymerization initiator. good.
Further, the compound in which the electron donating type polymerization initiator and the electron accepting type polymerization initiator form a salt with respect to each other may be used in combination with the above-mentioned electron donating type polymerization initiator or the above-mentioned electron accepting type polymerization initiator. It may be used in combination with a polymerization initiator.

[Preferable Embodiment of Infrared Absorbent and Electron Donating Polymerization Initiator]
In the image recording layer in the present disclosure, the HOMO value of the infrared absorber HOMO-electron donating polymerization initiator is preferably 0.70 eV or less, preferably 0.70 eV, from the viewpoint of improving sensitivity and printing resistance. It is more preferably ~ -0.10 eV.
A negative value means that the HOMO of the electron donating polymerization initiator is higher than that of the infrared absorber.

[Preferable aspects of electron-accepting polymerization initiator and infrared absorber]
In the image recording layer in the present disclosure, the value of LUMO of the electron-accepting polymerization initiator LUMO-infrared absorber is preferably 0.70 eV or less, preferably 1.00 eV, from the viewpoint of improving sensitivity and printing resistance. It is preferably ~ -0.10 eV, and more preferably 0.80 eV to 0.30 eV.
A negative value means that the LUMO of the infrared absorber is higher than that of the electron-accepting polymerization initiator.

[Infrared absorber]
The image recording layer in the present disclosure contains an infrared absorber.
The infrared absorber is not particularly limited, and examples thereof include pigments and dyes.
As the dye used as the infrared absorber, a commercially available dye and, for example, a known dye described in a document such as "Dye Handbook" (edited by the Society of Synthetic Organic Chemistry, published in 1970) can be used. Specifically, dyes such as azo dyes, metal complex salt azo dyes, pyrazolone azo dyes, naphthoquinone dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinoneimine dyes, methine dyes, cyanine dyes, squarylium dyes, pyrylium salts, and metal thiolate complexes. Can be mentioned.

Preferred of these dyes include cyanine dyes, squarylium dyes, pyrylium salts, nickel thiolate complexes, and indorenin cyanine dyes. More preferably, cyanine pigments and indorenin cyanine pigments are mentioned. Of these, the cyanine pigment is particularly preferable.

The infrared absorber is preferably a cationic polymethine dye having an oxygen atom, a nitrogen atom, or a halogen atom at the meso position. Preferred examples of the cationic polymethine dye include cyanine dye, pyrylium dye, thiopyrylium dye, and azulenium dye, and cyanine dye is preferable from the viewpoint of easy availability and solvent solubility during the introduction reaction.

Specific examples of the cyanine dye include the compounds described in paragraphs 0017 to 0019 of JP-A-2001-133769, paragraphs 0016 to 0021 of JP-A-2002-0233360, and paragraphs 0012 to 0037 of JP-A-2002-040638. , Preferably the compounds described in paragraphs 0034 to 0041 of JP-A-2002-278057, paragraphs 0080-0086 of JP-A-2008-195018, and particularly preferably paragraphs 0035 of JP-A-2007-90850. Examples thereof include the compounds described in Japanese Patent Application Laid-Open No. 2012-206495 and the compounds described in paragraphs 0105 to 0113 of JP2012-206495A.
Further, the compounds described in paragraphs 0008 to 0009 of JP-A-5-5005 and paragraphs 0022 to 0025 of JP-A-2001-222101 can also be preferably used. As the pigment, the compounds described in paragraphs 0072 to 0076 of JP-A-2008-195018 are preferable.

Further, as the infrared absorber, an infrared absorber that decomposes by infrared exposure can also be preferably used.
As the infrared absorber that decomposes by infrared exposure, those described in JP-A-2008-544322, International Publication No. 2016/027886, International Publication No. 2017/141882, or International Publication No. 2018/0432559 are preferably used. Can be used.
Further, as the infrared absorber that decomposes by infrared exposure, a decomposable compound used for the outermost layer, which will be described later, may be used.

Only one kind of infrared absorber may be used, or two or more kinds may be used in combination.
Further, a pigment and a dye may be used in combination as an infrared absorber.

The content of the infrared absorber is 0.1% by mass to 10.0% by mass with respect to the total mass of the image recording layer.
Is preferable, and 0.5% by mass to 5.0% by mass is more preferable.

〔particle〕
The image recording layer in the present disclosure preferably contains particles from the viewpoint of developability and UV printing resistance. The particles may be inorganic particles or organic particles.
Among them, the particles preferably contain organic particles, and more preferably polymer particles.
That is, the image recording layer in the present disclosure preferably contains polymer particles.
As the inorganic particles, known inorganic particles can be used, and metal oxide particles such as silica particles and titania particles can be preferably used.

[Polymer particles]
Examples of the polymer particles include particles containing an addition polymerization type resin (that is, addition polymerization type polymer particles), particles containing a polyaddition type resin (that is, polyaddition type polymer particles), and particles containing a polycondensation type resin (that is, that is). , Polycondensation type polymer particles), etc., among which addition polymerization type polymer particles or polyaddition type polymer particles are preferable.
Further, the polymer particles may be particles containing a thermoplastic resin (that is, thermoplastic polymer particles) from the viewpoint of enabling heat fusion.

Further, the polymer particles may be in the form of microcapsules, microgels (that is, crosslinked polymer particles) and the like.

The polymer particles are selected from the group consisting of thermoplastic polymer particles, heat-reactive polymer particles, polymer particles having a polymerizable group, microcapsules containing a hydrophobic compound, and microgels (crosslinked polymer particles). Is preferable. Of these, polymer particles having a polymerizable group are preferable.
In a particularly preferred embodiment, the polymer particles contain at least one ethylenically unsaturated group. The presence of such polymer particles has the effect of enhancing the printing durability of the exposed portion and the on-machine developability of the unexposed portion.

As the thermoplastic polymer particles, Research Disclosure No. 1 of January 1992. The thermoplastic polymer particles described in 33303, JP-A-9-123387, JP-A-9-131850, JP-A-9-171249, JP-A-9-171250, European Patent No. 913647, and the like are preferable.

Specific examples of the thermoplastic resin constituting the thermoplastic polymer particles include ethylene, styrene, vinyl chloride, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, vinylidene chloride, acrylonitrile, vinylcarbazole, and a polyalkylene structure. Examples thereof include homopolymers or copolymers of monomers such as acrylates or methacrylates having the above, or mixtures thereof.

The thermoplastic polymer particles preferably contain a structural unit formed of an aromatic vinyl compound and a thermoplastic resin having a structural unit having a nitrile group, from the viewpoint of ink fillability and UV printing resistance.

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

The content of the structural unit formed by the aromatic vinyl compound is preferably higher than the content of the structural unit having a nitrile group, which will be described later, from the viewpoint of ink inking property, with respect to the total mass of the thermoplastic resin. It is more preferably 15% by mass to 85% by mass, and even more preferably 30% by mass to 70% by mass.

The structural unit having a nitrile group is preferably introduced using a monomer having a nitrile group.
Examples of the monomer having a nitrile group include acrylonitrile compounds, and (meth) acrylonitrile is preferable.
As the structural unit having a nitrile group, a structural unit formed of (meth) acrylonitrile is preferable.

The content of the structural unit having a nitrile group is preferably smaller than the content of the structural unit formed by the aromatic vinyl compound from the viewpoint of ink inking property, and is 55% by mass with respect to the total mass of the resin. It is more preferably ~ 90% by mass, and more preferably 60% by mass to 85% by mass.

When the resin contained in the thermoplastic polymer particles contains a structural unit formed of an aromatic vinyl compound and a structural unit having a nitrile group, the structural unit formed of the aromatic vinyl compound and the structural unit having a nitrile group. The content ratio (constituent unit formed of the aromatic vinyl compound: structural unit having a nitrile group) is preferably 5: 5 to 9: 1 on a mass basis, and more preferably 6: 4 to 8. : 2.

The resin contained in the thermoplastic polymer particles preferably further has a structural unit formed of the N-vinyl heterocyclic compound from the viewpoint of UV printing resistance and chemical resistance.
Examples of the N-vinyl heterocyclic compound include N-vinylpyrrolidone, N-vinylcarbazole, N-vinylpyrrole, N-vinylphenothiazine, N-vinylsuccinic acidimide, N-vinylphthalimide, N-vinylcaprolactam, and N-vinylcaprolactum. Vinyl imidazole is mentioned, and N-vinylpyrrolidone is preferable.

The content of the structural unit formed by the N-vinyl heterocyclic compound is preferably 5% by mass to 50% by mass, and preferably 10% by mass to 40% by mass, based on the total mass of the thermoplastic resin. More preferred.

The resin contained in the thermoplastic polymer particles may contain a structural unit having an acidic group, but it is preferable not to contain a structural unit having an acidic group from the viewpoint of on-machine developability and ink inking property. ..
Specifically, the content of the structural unit having an acidic group in the thermoplastic resin is preferably 20% by mass or less, more preferably 10% by mass or less, and further preferably 5% by mass or less. preferable. The lower limit of the content is not particularly limited and may be 0% by mass. The acid value of the thermoplastic resin is preferably 160 mgKOH / g or less, more preferably 80 mgKOH / g or less, and even more preferably 40 mgKOH / g or less. The lower limit of the acid value is not particularly limited and may be 0 mgKOH / g.
In the present disclosure, the acid value is determined by a measuring method based on JIS K0070: 1992.

The resin contained in the thermoplastic polymer particles may contain a structural unit containing a hydrophobic group from the viewpoint of ink inking property.
Examples of the hydrophobic group include an alkyl group, an aryl group, an aralkyl group and the like.
As the structural unit containing the hydrophobic group, a structural unit formed of an alkyl (meth) acrylate compound, an aryl (meth) acrylate compound, or an aralkyl (meth) acrylate compound is preferable, and the structural unit is formed of an alkyl (meth) acrylate compound. The structural unit is more preferable.

The content of the structural unit having a hydrophobic group in the resin contained in the thermoplastic polymer particles is preferably 5% by mass to 50% by mass, preferably 10% by mass to 30% by mass, based on the total mass of the resin. It is more preferable to have.

The thermoplastic resin contained in the thermoplastic polymer particles preferably has a hydrophilic group from the viewpoint of UV printing resistance and on-machine developability.
The hydrophilic group is not particularly limited as long as it has a hydrophilic structure, and examples thereof include an acid group such as a carboxy group, a hydroxy group, an amino group, a nitrile group, and a polyalkylene oxide structure.
The hydrophilic group is preferably a group having a polyalkylene oxide structure, a group having a polyester structure, or a sulfonic acid group from the viewpoint of UV printing resistance and on-machine developability, and the polyalkylene oxide structure is preferably used. It is more preferably a group having or a sulfonic acid group, and further preferably a group having a polyalkylene oxide structure.

The polyalkylene oxide structure is preferably a polyethylene oxide structure, a polypropylene oxide structure, or a poly (ethylene oxide / propylene oxide) structure from the viewpoint of on-machine developability.
Further, from the viewpoint of on-machine developability, it is preferable to have a polypropylene oxide structure as the polyalkylene oxide structure among the above hydrophilic groups, and it is more preferable to have a polyethylene oxide structure and a polypropylene oxide structure.
From the viewpoint of on-machine developability, the number of alkylene oxide structures in the polyalkylene oxide structure is preferably 2 or more, more preferably 5 or more, further preferably 5 to 200, and 8 to 200. It is particularly preferably 150.

Further, from the viewpoint of on-machine developability, the group represented by the formula Z described later is preferable as the hydrophilic group.

Further, among the hydrophilic groups of the thermoplastic resin, the group represented by the following formula PO is preferable.

Wherein PO, ^{L P} each independently represent an alkylene group, ^{R P} represents a hydrogen atom or an alkyl group, n represents an integer of 1 to 100.
Wherein PO, L ^P are each independently an ethylene group, preferably a 1-methylethylene group, or a 2-methylethylene group, more preferably an ethylene group.
Wherein PO, it preferably R ^P is a hydrogen atom or an alkyl group having 1 to 18 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, a hydrogen atom or 1 to 4 carbon atoms It is more preferably an alkyl group, and particularly preferably a hydrogen atom or a methyl group.
In the formula PO, n is preferably an integer of 1 to 10, and more preferably an integer of 1 to 4.

The content of the structural unit having a hydrophilic group is preferably 5% by mass to 60% by mass, more preferably 10% by mass to 30% by mass, based on the total mass of the resin.

The resin contained in the thermoplastic polymer particles may further contain other structural units.
The other structural units may contain a structural unit other than the above-mentioned structural units without particular limitation, and examples thereof include structural units formed of an acrylamide compound, a vinyl ether compound, or the like.

The content of other structural units in the resin contained in the thermoplastic polymer particles is preferably 5% by mass to 50% by mass, and preferably 10% by mass to 30% by mass, based on the total mass of the resin. More preferred.

Examples of the heat-reactive polymer particles include polymer particles having a heat-reactive group.
The heat-reactive resin particles form a hydrophobic region by cross-linking due to a heat reaction and the change of functional groups at that time.

The heat-reactive group in the polymer particles having a heat-reactive group may be a functional group that undergoes any reaction as long as a chemical bond is formed, but a polymerizable group is preferable, and as an example, it is preferable. Eethylene unsaturated groups (eg, acryloyl group, methacryloyl group, vinyl group, allyl group, etc.), cationically polymerizable groups (eg, vinyl group, vinyloxy group, epoxy group, oxetanyl group, etc.), addition reaction Isocyanato group or a block thereof, an epoxy group, a vinyloxy group and a functional group having an active hydrogen atom which is a reaction partner thereof (for example, an amino group, a hydroxy group, a carboxy group, etc.), a carboxy group for performing a condensation reaction and a reaction. Preferred examples thereof include a hydroxy group or an amino group as a partner, an acid anhydride for carrying out a ring-opening addition reaction, and an amino group or a hydroxy group as a reaction partner.
The resin having the heat-reactive group may be an addition polymerization type resin, a polyaddition type resin, a polycondensation type resin, or a thermoplastic resin.

As the microcapsules, for example, as described in JP-A-2001-277740 and JP-A-2001-277742, those containing at least a part (preferably a hydrophobic compound) of the constituents of the image recording layer are preferable. .. In the image recording layer containing microcapsules as polymer particles, a hydrophobic component (that is, a hydrophobic compound) among the constituent components of the image recording layer is encapsulated in the microcapsules, and the hydrophilic component (that is, a hydrophilic compound) is microscopically contained. A configuration contained outside the capsule is a preferred embodiment.
Known synthetic methods can be applied to obtain microcapsules containing the components of the image recording layer.

The microgel (crosslinked polymer particles) can contain a part of the constituents of the image recording layer on at least one of the surface or the inside thereof. In particular, a reactive microgel having a polymerizable group on its surface is preferable from the viewpoint of the sensitivity of the lithographic printing plate original plate and the printing durability of the obtained lithographic printing plate.
A known synthetic method can be applied to obtain a microgel containing the constituents of the image recording layer.

The polymer particles are an adduct of a polyhydric phenol compound having two or more hydroxy groups in the molecule and isophorone diisocyanate from the viewpoint of printing resistance, stain resistance and storage stability of the obtained flat plate printing plate. The polyadductate polymer particles obtained by the reaction of the polyhydric isocyanate compound and the compound having active hydrogen are preferable.
As the polyvalent phenol compound, a compound having a plurality of benzene rings having a phenolic hydroxy group is preferable.
As the compound having active hydrogen, a polyol compound or a polyamine compound is preferable, a polyol compound is more preferable, and at least one compound selected from the group consisting of propylene glycol, glycerin and trimethylolpropane is further preferable.
Further, water may be used as the compound having active hydrogen. When water is used, the amine generated by the reaction between the isocyanate group of the polyhydric isocyanate compound and water forms a urea bond, and particles can be formed.
As the particles of the resin obtained by the reaction of the polyvalent isocyanate compound which is an adduct of the polyhydric phenol compound having two or more hydroxy groups in the molecule and the isophorone diisocyanate, and the compound having active hydrogen, the first international release. Preferred are microgels obtained by the preparation method according to paragraphs 0230 to 0234 of No. 2018/043259.

Further, the polymer particles have a hydrophobic main chain from the viewpoint of printing resistance and solvent resistance of the obtained flat plate printing plate, and i) have a nitrile group directly bonded to the hydrophobic main chain. Additionally polymerized polymer particles containing both a constituent unit and ii) a constituent unit having a pendant group containing a hydrophilic polyalkylene oxide segment are preferred.
Specifically, the particles described in paragraph 0156 of JP-A-2019-64269 are preferable as such addition polymerization type polymer particles.

(Group represented by formula Z)
The polymer particles in the present disclosure preferably have a group represented by the following formula Z as a hydrophilic group.
In particular, the polymer particles in the present disclosure are preferably addition polymerization type polymer particles having a hydrophilic group including a group represented by the following formula Z.
Formula Z: * -Q-W-Y
In formula Z, Q represents a divalent linking group, W represents a divalent group having a hydrophilic structure or a divalent group having a hydrophobic structure, and Y represents a monovalent group having a hydrophilic structure or a monovalent group having a hydrophilic structure. A monovalent group having a hydrophobic structure is represented, either W or Y has a hydrophilic structure, and * represents a binding site with another structure.
Further, it is preferable that any of the hydrophilic structures contained in the formula Z contains a polyalkylene oxide structure.

Q in the above formula Z is preferably a divalent linking group having 1 to 20 carbon atoms, and more preferably a divalent linking group having 1 to 10 carbon atoms.
Further, Q in the above formula Z is preferably an alkylene group, an arylene group, an ester bond, an amide bond, or a group in which two or more of these are combined, and more preferably a phenylene group, an ester bond, or an amide bond. ..

The divalent group having a hydrophilic structure in W of the above formula Z is preferably a group containing a polyalkylene oxide structure, and is a polyalkylene oxy group or -CH ₂ CH at one end of the polyalkylene oxy group. It is preferably a group to which ₂ NR ^{W − is bound.} Incidentally, R ^W represents a hydrogen atom or an alkyl group, the same applies to the subsequent R ^W.
The divalent group having a hydrophobic structure in the W of formula ^{Z, -R WA -, - O} -R WA -O -, - R W N-R WA -NR W -, - OC (= O) - R ^WA -O-, or, -OC (= ^O) is preferably ^-R WA -O-. ^{Incidentally, R WA} is independently a linear of 6 to 120 carbon atoms, branched or cyclic alkylene group, haloalkylene group of 6 to 120 carbon atoms, an arylene group having 6 to 120 carbon atoms, of 7 to 120 carbon atoms It represents an alkanerylene group (a divalent group obtained by removing one hydrogen atom from an alkylaryl group) or an aralkylene group having 7 to 120 carbon atoms.

The monovalent group having a hydrophilic structure in Y of the above formula Z is -OH, -C (= O) OH, a polyalkyleneoxy group having a hydrogen atom or an alkyl group at the end, or a hydrogen atom or an alkyl at the end. it is preferably bound group - at the other end of the polyalkyleneoxy group is a group ^{_{-CH 2 CH 2 N (R W}} ). Among them, the monovalent group having a hydrophilic structure is preferably a group containing a polyalkylene oxide structure, a polyalkyleneoxy group having a hydrogen atom or an alkyl group at the end, or a hydrogen atom or an alkyl group at the end. in polyalkyleneoxy groups other end to the ^{_{-CH 2 CH 2 N (R W}} ) is - is bonded group.
The monovalent group having a hydrophobic structure in Y of the above formula Z is a linear, branched or cyclic alkyl group having 6 to 120 carbon atoms, a haloalkyl group having 6 to 120 carbon atoms, an aryl group having 6 to 120 carbon atoms, and the like. It may be an alcoholyl group (alkylaryl group) having 7 to 120 carbon atoms, an aralkyl group having 7 to 120 carbon atoms, -OR ^WB , -C (= O) OR ^WB , or -OC (= O) R ^WB. preferable. R ^WB represents an alkyl group having 6 to 20 carbon atoms.

The polymer particles having a group represented by the above formula Z are more preferably divalent groups in which W has a hydrophilic structure from the viewpoints of print resistance, fillability and on-machine developability. It is more preferable that Q is a phenylene group, an ester bond or an amide bond, W is a polyalkyleneoxy group, and Y is a polyalkyleneoxy group having a hydrogen atom or an alkyl group at the end.
The group represented by the formula Z may function as a dispersible group that enhances the dispersibility of the polymer particles.

The polymer particles in the present disclosure preferably have a polymerizable group (preferably an ethylenically unsaturated group) from the viewpoint of print resistance and on-machine developability, and in particular, may have a polymerizable group on the surface. More preferred. By using the polymer particles having a polymerizable group, it becomes easy to suppress plate skipping (preferably UV plate skipping), and printing resistance (preferably UV printing resistance) is also enhanced.

From the viewpoint of printing resistance, the polymer particles in the present disclosure are preferably resin particles having a hydrophilic group and a polymerizable group.
The polymerizable group may be a cationically polymerizable group or a radically polymerizable group, but from the viewpoint of reactivity, it is preferably a radically polymerizable group.
The polymerizable group is not particularly limited as long as it is a polymerizable group, but from the viewpoint of reactivity, an ethylenically unsaturated group is preferable, and a vinylphenyl group (styryl group), a (meth) acryloxy group, or a (meth) acryloxy group is preferable. A (meth) acrylamide group is more preferred, and a (meth) acryloxy group is particularly preferred.
Further, the resin constituting the polymer particles having a polymerizable group preferably has a structural unit having a polymerizable group.
In addition, a polymerizable group may be introduced on the surface of the polymer particles by a polymer reaction.

Further, the polymer particles preferably contain a heavy addition type resin having a urea bond from the viewpoints of printing resistance, inking property, on-machine developability, and ability to suppress development residue during on-machine development, and the following formula is preferable. It is more preferable to contain a heavy addition type resin having a structure obtained by at least reacting the isocyanate compound represented by (Iso) with water, and at least reacting the isocyanate compound represented by the following formula (Iso) with water. It is particularly preferable that the polyoxyalkylene structure contains a polyadditive resin having a polyethylene oxide structure and a polypropylene oxide structure. Further, the particles containing the heavy addition type resin having a urea bond are preferably microgels.

In the formula (Iso), n represents an integer of 0 to 10.

As an example of the reaction between the isocyanate compound represented by the above formula (Iso) and water, the reaction shown below can be mentioned. The following example is an example using n = 0, 4,4-isomer.
As shown below, when the isocyanate compound represented by the above formula (Iso) is reacted with water, a part of the isocyanate group is hydrolyzed by water to generate an amino group, and the generated amino group and isocyanate group are used. React to form a urea bond and form a dimer. Further, the following reaction is repeated to form a heavy addition type resin having a urea bond.

Further, in the following reaction, by adding a compound having reactivity with an isocyanate group such as an alcohol compound or an amine compound (a compound having active hydrogen), the structure of the alcohol compound, the amine compound or the like is added with a urea bond. It can also be introduced into the mold resin.
As the compound having active hydrogen, the above-mentioned compound having active hydrogen is preferably mentioned.

Further, the heavy addition type resin having a urea bond preferably has an ethylenically unsaturated group, and more preferably has a group represented by the following formula (PETA).

In the formula (PETA), the wavy line portion represents the position of connection with other structures.

(Synthesis of polymer particles)
The method for synthesizing the polymer particles is not particularly limited, and any method may be used as long as the particles can be synthesized with the various resins described above. Examples of the method for synthesizing polymer particles include known methods for synthesizing polymer particles, such as an emulsion polymerization method, a suspension polymerization method, a dispersion polymerization method, a soap-free polymerization method, and a microemulsion polymerization method.
In addition, a known method for synthesizing microcapsules, a method for synthesizing microgels (crosslinked resin particles), or the like may be used for synthesizing polymer particles.

(Average particle size of particles)
The average particle size of the particles is preferably 0.01 μm to 3.0 μm, more preferably 0.03 μm to 2.0 μm, and even more preferably 0.10 μm to 1.0 μm. Good resolution and stability over time can be obtained in this range.
The average particle size of the particles is measured by the light scattering method, or an electron micrograph of the particles is taken, and a total of 5,000 particle sizes are measured on the photograph to calculate the average value. do. For non-spherical particles, the diameter is equivalent to the circle of the particles on the photograph.
Unless otherwise specified, the average particle size of the particles in the present disclosure shall be the volume average particle size.

As the particles (preferably polymer particles), only one kind may be used, or two or more kinds may be used in combination.

The content of the particles (preferably polymer particles) is preferably 5% by mass to 90% by mass, preferably 10% by mass to 90% by mass, based on the total mass of the image recording layer from the viewpoint of developability and print resistance. It is more preferably 20% by mass to 90% by mass, and particularly preferably 50% by mass to 90% by mass.

[Other ingredients]
The image recording layer in the present disclosure may contain other components other than the above-mentioned components.
Examples of other components include binder polymers, color formers, chain transfer agents, low molecular weight hydrophilic compounds, fat sensitizers, and other additives.

[Binder polymer]
The image recording layer may contain a binder polymer.
The image recording layer may contain a binder polymer, if desired.
Here, the binder polymer refers to a polymer other than polymer particles, that is, a polymer that is not in the form of particles.
Further, the binder polymer excludes the ammonium salt-containing polymer in the oil-sensitive agent and the polymer used as a surfactant.

As the binder polymer, a known binder polymer (for example, (meth) acrylic resin, polyvinyl acetal, polyurethane resin, etc.) used for the image recording layer of the lithographic printing plate original plate can be preferably used.
As an example, a binder polymer (hereinafter, also referred to as a binder polymer for on-machine development) used in the machine-developed lithographic printing plate original plate will be described in detail.
As the binder polymer for on-machine development, a binder polymer having an alkylene oxide chain is preferable. The binder polymer having an alkylene oxide chain may have a poly (alkylene oxide) moiety in the main chain or the side chain. Further, it may be a graft polymer having poly (alkylene oxide) in the side chain, or a block copolymer of a block composed of poly (alkylene oxide) -containing repeating units and a block composed of (alkylene oxide) -free repeating units.
When the main chain has a poly (alkylene oxide) moiety, a polyurethane resin is preferable.
When the polymer of the main chain has a poly (alkylene oxide) moiety in the side chain, the polymer of the main chain is (meth) acrylic resin, polyvinyl acetal resin, polyurethane resin, polyurea resin, polyimide resin, polyamide resin, epoxy resin, polystyrene resin, novolak type. Examples thereof include phenol resin, polyester resin, synthetic rubber and natural rubber, and (meth) acrylic resin is particularly preferable.

The image recording layer in the present disclosure preferably contains polyvinyl acetal.
Polyvinyl acetal is a compound obtained by acetalizing polyvinyl alcohol with an aldehyde.
Examples of the polyvinyl acetal include polyvinyl butyral and polyvinyl formal.
For example, polyvinyl butyral contains the following building blocks:

The polyvinyl acetal preferably further contains a structural unit having a hydroxyl group from the viewpoint of on-machine developability and the like.
Examples of the structural unit having a hydroxyl group include the structural units shown below. That is, the polyvinyl acetal preferably contains a structural unit derived from vinyl alcohol.

The polyvinyl acetal may further contain other structural units.
Examples of other structural units include the following structural units.

From the viewpoint of on-machine developability, the polyvinyl acetal has a content of a structural unit having a hydroxyl group (preferably a structural unit derived from the vinyl alcohol) of 15 mol% or more with respect to all the structural units in the polyvinyl acetal. It is preferably 20 mol% or more, more preferably 25 mol% or more, and further preferably 25 mol% or more.
The upper limit of the content of the structural unit having a hydroxyl group with respect to all the structural units in the polyvinyl acetal is, for example, 50 mol%.

The weight average molecular weight of the polyvinyl acetal is preferably 10,000 to 150,000.

As the polyvinyl acetal, a synthetic product or a commercially available product may be used.
Examples of commercially available polyvinyl acetal products include Sekisui Chemical Co., Ltd.'s Eslek series (specifically, BL-1, BL-10, BX-5 (Z), and the like.

Further, as another preferable example of the binder polymer, a high molecular weight polymer chain having a polyfunctional thiol having 6 or more functionalities or 10 functionalities as a nucleus and being bonded to the nucleus by a sulfide bond, and the polymer chain having a polymerizable group. Examples thereof include molecular compounds (hereinafter, also referred to as star-shaped polymer compounds).
As the star-shaped polymer compound, for example, the compound described in JP-A-2012-148555 can be preferably used.

The star-shaped polymer compound contains a polymerizable group such as an ethylenically unsaturated bond for improving the film strength of the image portion as described in JP-A-2008-195018, with a main chain or a side chain, preferably a side chain. Examples include those held in the chain. The polymerizable group of the star-shaped polymer compound forms crosslinks between the molecules of the star-shaped polymer compound, and curing is promoted.
As the polymerizable group, an ethylenically unsaturated group such as a (meth) acrylic group, a vinyl group, an allyl group, a vinylphenyl group (styryl group), an epoxy group and the like are preferable, and a (meth) acrylic group, a vinyl group and a vinylphenyl are preferable. A group (styryl group) is more preferable from the viewpoint of polymerization reactivity, and a (meth) acrylic group is particularly preferable. These groups can be introduced into the polymer by polymer reaction or copolymerization. Specifically, for example, a reaction between a polymer having a carboxy group in the side chain and glycidyl methacrylate, or a reaction between a polymer having an epoxy group and an ethylenically unsaturated group-containing carboxylic acid such as methacrylic acid can be used.

The molecular weight of the binder polymer is preferably 2,000 or more, more preferably 5,000 or more, and 10,000 to 300,000 in terms of polystyrene conversion value by the GPC method. It is more preferable to have.

As the binder polymer, a hydrophilic polymer such as polyacrylic acid or polyvinyl alcohol described in JP-A-2008-195018 can be used in combination, if necessary. Further, a lipophilic polymer and a hydrophilic polymer can be used in combination.

The binder polymer may be used alone or in combination of two or more.

The binder polymer can be contained in the image recording layer in an arbitrary amount, but the content of the binder polymer is preferably 1% by mass to 90% by mass with respect to the total mass of the image recording layer. It is more preferably 5% by mass to 80% by mass.

[Color former]
The image recording layer may contain a color former.
The color-developing agent is preferably an acid color-developing agent. Further, the color former preferably contains a leuco compound (also referred to as a leuco dye).
The "color former" used in the present disclosure means a compound having a property of developing or decoloring a color or decoloring by a stimulus such as light or acid and changing the color of the image recording layer, and the "acid color former" is used. It means a compound having a property of developing or decoloring and changing the color of an image recording layer by heating in a state of receiving an electron-accepting compound (for example, a proton such as an acid).
The acid color former has a partial skeleton such as lactone, lactam, salton, spiropyrane, ester, and amide, and is colorless and the partial skeleton is rapidly ring-opened or cleaved when it comes into contact with an electron-accepting compound. Compounds are preferred.

Examples of the acid color former include the compounds described in paragraphs 0184 to 0191 of JP-A-2019-18412.

Among them, the color former is preferably at least one compound selected from the group consisting of a spiropyran compound, a spiroxazine compound, a spirolactone compound, and a spirolactam compound from the viewpoint of color development.
As the hue of the color former after color development, it is preferable to have maximum absorption in the range of 450 nm to 650 nm from the viewpoint of visibility. The color of the color-developing agent after color development is preferably red, purple, blue, or black-green.

Further, as the coloring agent (preferably an acid coloring agent), it is preferable to use a leuco dye from the viewpoint of enhancing the visibility of the exposed portion.
Here, the leuco dye is not particularly limited as long as it is a dye having a leuco structure, but it is preferably having a spiro structure, and more preferably a spirolactone ring structure.
Further, the leuco dye is preferably a leuco dye having a phthalide structure or a fluorane structure from the viewpoint of enhancing the visibility of the exposed portion.

Further, the color-developing agent (preferably an acid color-developing agent) is a leuco dye having the above-mentioned phthalide structure or fluorane structure from the viewpoint of enhancing the visibility of the exposed portion, and is the following formulas (Le-1) to (Le-3). ) Is preferable, and a compound represented by the following formula (Le-2) is more preferable.

Wherein (Le-1) ~ formula (Le-3), ERG each independently represents an electron donating _group, X 1 to X ₄ each independently represent a hydrogen atom, a halogen atom, or a dialkyl anilino _{X 5 to} X ₁₀ each independently represent a hydrogen atom, a halogen atom, or a monovalent organic group, Y ₁ and Y ₂ each independently represent C or N, and Y _{1 represents a group.} When N, X ₁ does not exist, when Y ₂ is N, X ₄ does not exist, Ra ₁ represents a hydrogen atom, an alkyl group, or an alkoxy group, and Rb _{1 to Rb 4} Independently represent a hydrogen atom, an alkyl group, or an aryl group.

The electron donating groups in the ERGs of the formulas (Le-1) to (Le-3) include amino groups, alkylamino groups, arylamino groups, and dialkylaminos from the viewpoint of color development and visibility of the exposed portion. A group, a monoalkyl monoarylamino group, a diarylamino group, an alkoxy group, an aryloxy group, or an alkyl group is preferable, and an amino group, an alkylamino group, an arylamino group, a dialkylamino group, a monoalkyl monoarylamino group, It is more preferably a diarylamino group, an alkoxy group, or an aryloxy group, further preferably an arylamino group, a monoalkyl monoarylamino group, or a diarylamino group, and an arylamino group or a monoalkyl monoarylamino group. Is particularly preferable.
_X 1 to X ₄ in the formula (Le-1) ~ formula (Le-3) are each independently, from the viewpoint of enhancing the visibility of the exposure unit, a hydrogen atom, or, preferably a chlorine atom, a hydrogen atom Is more preferable.
_{X 5 to} X ₁₀ in the formula (Le-2) or the formula (Le-3) are independently hydrogen atom, halogen atom, alkyl group, aryl group, amino group, from the viewpoint of enhancing the visibility of the exposed part. Being an alkylamino group, an arylamino group, a dialkylamino group, a monoalkyl monoarylamino group, a diarylamino group, a hydroxy group, an alkoxy group, an aryloxy group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, or a cyano group. Is preferable, a hydrogen atom, a halogen atom, an alkyl group, an aryl group, an alkoxy group, or an aryloxy group is more preferable, and a hydrogen atom, a halogen atom, an alkyl group, or an aryl group is more preferable, and a hydrogen atom is used. It is particularly preferable to have.
_{It is preferable that at least one of Y 1} and Y ₂ in the formulas (Le-1) to (Le-3) is C from the viewpoint of enhancing the visibility of the exposed portion, _{and both Y 1} and Y ₂ are used. It is more preferably C.
_{Ra 1} in the formula (Le-3) is preferably an alkyl group or an alkoxy group, more preferably an alkoxy group, and particularly preferably a methoxy group, from the viewpoint of enhancing the visibility of the exposed portion.
_{Each of Rb 1 to Rb 4} in the formula (Le-1) is preferably a hydrogen atom or an alkyl group, more preferably an alkyl group, and a methyl group, independently from the viewpoint of enhancing the visibility of the exposed portion. Is particularly preferable.

Further, from the viewpoint of enhancing the visibility of the exposed portion, the leuco dye having the phthalide structure or the fluorane structure is described in the following formulas (Le-4) to (Le-6). The compound represented by any of the above is more preferable, and the compound represented by the following formula (Le-5) is further preferable.

In formulas (Le-4) to (Le-6), ERG independently represent an electron donating group, and X _{1 to} X ₄ independently represent a hydrogen atom, a halogen atom, or a dialkylanilino. Represents a group, Y ₁ and Y ₂ independently represent C or N, where X ₁ does not exist _{when Y 1} is N and X ₄ exists _{when Y 2 is N.} Instead, Ra ₁ represents a hydrogen atom, an alkyl group, or an alkoxy group, and Rb _{1 to Rb 4} independently represent a hydrogen atom, an alkyl group, or an aryl group, respectively.

_{ERG, X 1 to} X ₄ , Y ₁ , Y ₂ , Ra ₁ and Rb _{1 to} Rb 4 in the formulas (Le-4) to (Le-6) are the formulas (Le-1) to the formulas (Le-1) to _{Rb 4, respectively.} le-3) _{ERG in, X 1 ~X 4, Y 1} , Y 2, Ra 1 and have _the same meanings as Rb 1 ~Rb _4, preferable embodiments thereof are also the same.

Further, from the viewpoint of enhancing the visibility of the exposed portion, the leuco dye having the phthalide structure or the fluorane structure is described in the following formulas (Le-7) to (Le-9). The compound represented by any of the above is more preferable, and the compound represented by the following formula (Le-8) is particularly preferable.

Wherein (Le-7) ~ formula _{(Le-9), X 1} ~X 4 each independently represent a hydrogen atom, a halogen atom or a dialkyl anilino group, _{Y 1} and _{Y 2} are each independently Representing C or N, if Y ₁ is N, then X ₁ does not exist, if Y ₂ is N, then X ₄ does not exist, and Ra _{1 to Ra 4} are independent of hydrogen. Representing an atom, an alkyl group, or an alkoxy group, Rb _{1 to Rb 4} independently represent a hydrogen atom, an alkyl group, or an aryl group, and Rc ₁ and Rc ₂ each independently represent an aryl group.

_{X 1 ~X} 4, _Y 1 and _{Y 2} in Formula (Le-7) to Formula (Le-9) has the formula _{(Le-1) X 1 ~X} 4 in ~ formula (Le-3), _{Y 1} and It has the same meaning as Y ₂ , and the preferred embodiment is also the same.
_{Ra 1 to Ra 4} in the formula (Le-7) or the formula (Le-9) are each independently preferably an alkyl group or an alkoxy group from the viewpoint of enhancing the visibility of the exposed portion, and are alkoxy groups. It is more preferable, and it is particularly preferable that it is a methoxy group.
_{Rb 1 to Rb 4} in the formulas (Le-7) to (Le-9) are independently substituted with a hydrogen atom, an alkyl group, or an alkyl group or an alkoxy group from the viewpoint of enhancing the visibility of the exposed portion. It is preferably an aryl group, more preferably a hydrogen atom or an alkyl group, and particularly preferably a hydrogen atom or a methyl group.
_{Rc 1} and Rc ₂ in the formula (Le-8) are preferably phenyl groups or alkylphenyl groups, and more preferably phenyl groups, independently from the viewpoint of enhancing the visibility of the exposed portion. ..
Further, in the formula (Le-8), from the viewpoint of enhancing the visibility of the exposed portion, it is preferable that _{X 1 to} X ₄ are hydrogen atoms and Y ₁ and Y _{2 are C.}
Further, in the formula (Le-8), from the viewpoint of enhancing the visibility of the exposed portion, Rb ₁ and Rb ₂ are independently substituted with a hydrogen atom, an alkyl group, or an alkyl group or an alkoxy group. It is preferably present, and more preferably a hydrogen atom or an alkyl group.

The alkyl group in the formulas (Le-1) to (Le-9) may be linear, may have a branch, or may have a ring structure.
Further, the number of carbon atoms of the alkyl group in the formulas (Le-1) to (Le-9) is preferably 1 to 20, more preferably 1 to 8, and further preferably 1 to 4. It is preferably 1 or 2, and particularly preferably 1.
The number of carbon atoms of the aryl group in the formulas (Le-1) to (Le-9) is preferably 6 to 20, more preferably 6 to 10, and particularly preferably 6 to 8.

Further, each group such as a monovalent organic group, an alkyl group, an aryl group, a dialkylanilino group, an alkylamino group and an alkoxy group in the formulas (Le-1) to (Le-9) has a substituent. May be. The substituents include an alkyl group, an aryl group, a halogen atom, an amino group, an alkylamino group, an arylamino group, a dialkylamino group, a monoalkyl monoarylamino group, a diallylamino group, a hydroxy group, an alkoxy group, an aryloxy group and an acyl group. Examples thereof include a group, an alkoxycarbonyl group, an aryloxycarbonyl group, a cyano group and the like. Further, these substituents may be further substituted with these substituents.

Specific examples of the leuco dye having a phthalide structure or a fluorine structure that are preferably used include the following compounds (S-1 to S-15).

As the acid color former, it is also possible to use products on the market, such as ETAC, RED500, RED520, CVL, S-205, BLACK305, BLACK400, BLACK100, BLACK500, H-7001, GREEN300, NIRBLACK78, BLUE220, H. -3035, BLUE203, ATP, H-1046, H-2114 (all manufactured by Fukui Yamada Chemical Industry Co., Ltd.), ORANGE-DCF, Vermilion-DCF, PINK-DCF, RED-DCF, BLMB, CVL, GREEN-DCF , TH-107 (all manufactured by Hodogaya Chemical Co., Ltd.), ODB, ODB-2, ODB-4, ODB-250, ODB-BlackXV, Blue-63, Blue-502, GN-169, GN-2, Green -118, Red-40, Red-8 (all manufactured by Yamamoto Kasei Co., Ltd.), crystal violet lactone (manufactured by Tokyo Chemical Industry Co., Ltd.) and the like can be mentioned.
Among these commercially available products, ETAC, S-205, BLACK305, BLACK400, BLACK100, BLACK500, H-7001, GREEN300, NIRBLACK78, H-3035, ATP, H-1046, H-2114, GREEN-DCF, Blue-63. , GN-169, and crystal violet lactone are preferable because the film to be formed has a good visible light absorption rate.

As the leuco dye, the following compounds are also preferably used from the viewpoint of enhancing the visibility of the exposed portion.

The color former may be used alone or in combination of two or more.

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

The image recording layer may contain components other than those described above.
Ingredients other than those described above include colorants, baking agents, polymerization inhibitors, higher fatty acid derivatives, plasticizers, inorganic fine particles, and low molecular weight hydrophilicity described in paragraphs 0181 to 0190 of JP2009-255434A. Examples include compounds.
In addition, as components other than those described above, the hydrophobizing precursor (fine particles capable of converting the image recording layer into hydrophobicity when heat is applied) described in paragraphs 0191 to 0217 of JP2012-187907A. Examples thereof include low molecular weight hydrophilic compounds, fat sensitizers (for example, phosphonium compounds, nitrogen-containing low molecular weight compounds, ammonium group-containing polymers), chain transfer agents and the like.

[Formation of image recording layer]
In the image recording layer in the lithographic printing plate original plate according to the present disclosure, for example, as described in paragraphs 0142 to 0143 of JP-A-2008-195018, the necessary components are dispersed or dissolved in a known solvent. It can be formed by preparing a coating liquid, applying the coating liquid on a support by a known method such as bar coater coating, and drying the coating liquid.

As the solvent used for the coating liquid, a known solvent can be used. Specifically, for example, water, acetone, methyl ethyl ketone (2-butanone), cyclohexane, ethyl acetate, ethylene dichloride, tetrahydrofuran, toluene, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, propylene glycol monomethyl ether, Propropylene glycol monoethyl ether, acetylacetone, cyclohexanone, diacetone alcohol, ethylene glycol monomethyl ether acetate, ethylene glycol ethyl ether acetate, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether acetate, 1-methoxy-2-propanol, 3- Methoxy-1-propanol, methoxymethoxyethanol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, 3-methoxypropyl acetate, N, N-dimethyl Examples thereof include formamide, dimethylsulfoxide, γ-butyrolactone, methyl lactate, ethyl lactate and the like.
The solvent may be used alone or in combination of two or more.
The solid content concentration in the coating liquid is preferably 1% by mass to 50% by mass.

The coating amount (solid content) of the image recording layer after coating and drying varies depending on the application, but from the viewpoint of obtaining good sensitivity and good film characteristics of the image recording layer, 0.3 g / m ^{2 to} 3.0 g /. m ² is preferable.
Further, the film thickness of the image recording layer in the lithographic printing plate original plate according to the present disclosure is preferably 0.1 μm to 3.0 μm, and more preferably 0.3 μm to 2.0 μm.

<Outermost layer>
The lithographic printing plate original plate according to the present disclosure may have an outermost layer (also referred to as a protective layer or an overcoat layer) on the image recording layer.
Further, the outermost layer may have a function of suppressing an image formation inhibition reaction by blocking oxygen, a function of preventing scratches on the surface of the image recording layer, a function of preventing ablation during high-illuminance laser exposure, and the like.

The outermost layer of such characteristics is described, for example, in US Pat. Nos. 3,458,311 and JP-A-55-49729. As the oxygen low-permeability polymer used for the outermost layer, either a water-soluble polymer or a water-insoluble polymer can be appropriately selected and used, and if necessary, two or more kinds may be mixed and used. can. Specific examples thereof include polyvinyl alcohol, modified polyvinyl alcohol, polyvinylpyrrolidone, water-soluble cellulose derivatives, poly (meth) acrylonitrile, and the like.
As the modified polyvinyl alcohol, an acid-modified polyvinyl alcohol having a carboxy group or a sulfo group is preferably used. Specific examples thereof include the modified polyvinyl alcohols described in JP-A-2005-250216 and JP-A-2006-259137.

[Inorganic layered compound]
The outermost layer preferably contains an inorganic layered compound in order to enhance oxygen blocking property. Inorganic laminar compound is a particle having a thin tabular shape, for example, natural mica, micas such as synthetic mica, wherein: talc represented by 3MgO · 4SiO · H 2 _O, teniolite, montmorillonite, saponite, hectorite Examples include light, zirconium phosphate and the like.
The inorganic layered compound preferably used is a mica compound. Examples of the mica compound include the formula: A (B, C) _2-5 D ₄ O ₁₀ (OH, F, O) ₂ [However, A is any of K, Na and Ca, and B and C are It is any of Fe (II), Fe (III), Mn, Al, Mg, and V, and D is Si or Al. ], Mica groups such as natural mica and synthetic mica can be mentioned.

In the mica group, natural mica includes muscovite, paragonite, phlogopite, biotite and lepidolite. As synthetic mica, non-swelling mica such as fluorine gold mica KMg ₃ (AlSi ₃ O ₁₀ ) F ₂ , potash tetrasilicon mica KM g _2.5 Si ₄ O ₁₀ ) F _{2 , and Na tetrasilic mica NaMg 2. 5} (Si ₄ O ₁₀ ) F ₂ , Na or Li teniolite (Na, Li) Mg ₂ Li (Si ₄ O ₁₀ ) F ₂ , montmorillonite-based Na or Li hectrite (Na, Li) _1/8 Mg _{2 /} Examples thereof include swelling mica such as ₅ Li _1/8 (Si ₄ O ₁₀ ) F _2. In addition, synthetic smectites are also useful.

Among the above mica compounds, fluorine-based swelling mica is particularly useful. That is, the swellable synthetic mica has a laminated structure composed of a unit crystal lattice layer having a thickness of about 10 Å to 15 Å (1 Å = 0.1 nm), and the metal atom substitution in the lattice is significantly larger than that of other clay minerals. As a result, the lattice layer causes a positive charge shortage, and in order to compensate for it, cations such as ^{Li +} , Na ⁺ , Ca ²⁺ , and Mg ^{2+ are adsorbed between the layers.} The cations intervening between these layers are called commutative cations and can be exchanged with various cations. In particular, when the cations between layers are Li ⁺ and Na ⁺ , the bond between the layered crystal lattices is weak because the ionic radius is small, and the cations are greatly swollen by water. When share is applied in that state, it easily cleaves and forms a stable sol in water. Swellable synthetic mica has a strong tendency to this and is particularly preferably used.

As for the shape of the mica compound, from the viewpoint of diffusion control, the thinner the thickness, the better, and the plane size is better as long as it does not impair the smoothness of the coated surface and the permeability of the active light beam. Therefore, the aspect ratio is preferably 20 or more, more preferably 100 or more, and particularly preferably 200 or more. The aspect ratio is the ratio of the major axis to the thickness of the particle, which can be measured, for example, from a micrograph projection of the particle. The larger the aspect ratio, the greater the effect obtained.

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

The content of the inorganic layered compound is preferably 1% by mass to 60% by mass, more preferably 3% by mass to 50% by mass, based on the total solid content of the outermost layer. Even when a plurality of types of inorganic layered compounds are used in combination, it is preferable that the total amount of the inorganic layered compounds is the above-mentioned content. Oxygen blocking property is improved in the above range, and good sensitivity can be obtained. In addition, it is possible to prevent a decrease in meat-forming property.

[Discoloring compound]
The outermost layer may contain a discolorating compound from the viewpoint of enhancing the visibility of the exposed portion.

From the viewpoint of enhancing the visibility of the exposed portion, the lithographic printing plate original plate according to the present disclosure has a brightness change ΔL before and after exposure when exposed to infrared rays ^{having an energy density of 110 mJ / cm 2 and a wavelength of 830 nm.} It is preferably 0 or more.
The brightness change ΔL is more preferably 3.0 or more, further preferably 5.0 or more, particularly preferably 8.0 or more, and most preferably 10.0 or more.
As the upper limit of the brightness change ΔL, for example, 20.0 can be mentioned.
Further, in particular, when the outermost layer containing the discolorating compound is provided, it is preferable to satisfy the above-mentioned preferable numerical range of the above-mentioned brightness change ΔL.

The brightness change ΔL is measured by the following method.
The original plate for lithographic printing is printed by FUJIFILM Graphic Systems Co., Ltd.'s Luxel PLATESETTER T-9800 equipped with an infrared semiconductor laser with a wavelength of 830 nm. Output 99.5%, outer drum rotation speed 220 rpm, resolution 2,400 dpi (dots per inch, Exposure is performed under the condition of 1 inch = 25.4 mm) (energy density 110 mJ / cm ² ). The exposure is performed in an environment of 25 ° C. and 50% RH.
Measure the change in brightness of the lithographic printing plate original before and after exposure.
A spectrophotometer eXact manufactured by X-Rite is used for the measurement. Using the L ^* a ^* b ^* color system L ^* value (brightness), the absolute value of the difference between the ^{L *} value of the image recording layer after ^{exposure and the L *} value of the image recording layer before exposure is changed by the brightness change ΔL. And.

In the present disclosure, the "discolorable compound" refers to a compound whose absorption in the visible light region (wavelength: 400 nm or more and less than 750 nm) changes due to infrared exposure. That is, in the present disclosure, "discoloration" means that the absorption in the visible light region (wavelength: 400 nm or more and less than 750 nm) changes due to infrared exposure.
Specifically, the discolorable compounds in the present disclosure are (1) a compound in which absorption in the visible light region is increased due to infrared exposure compared to before infrared exposure, and (2) absorption in the visible light region due to infrared exposure. (3) Compounds that do not have absorption in the visible light region due to infrared exposure can be mentioned.
The infrared rays in the present disclosure are light rays having a wavelength of 750 nm to 1 mm, and preferably light rays having a wavelength of 750 nm to 1,400 nm.

The discolorating compound preferably contains a compound that develops color due to infrared exposure.
Further, the discolorating compound preferably contains a decomposable compound that decomposes due to infrared exposure, and particularly includes a decomposable compound that decomposes due to heat, electron transfer, or both due to infrared exposure. Is preferable.
More specifically, the discolorable compounds in the present disclosure are degraded by infrared exposure (more preferably by heat, electron transfer, or both due to infrared exposure) and before infrared exposure. It is preferable that the compound has an increase in absorption in the visible light region, or the absorption has a shorter wavelength and has absorption in the visible light region.
Here, "decomposition by electron transfer" means that an electron excited from HOMO (highest occupied orbital) to LUMO (lowest empty orbital) of a discolorable compound by infrared exposure is an electron accepting group (LUMO and potential) in the molecule. It means that the electron transfers in the molecule to a group close to), and the decomposition occurs accordingly.

Hereinafter, the degradable compound, which is an example of the discolorable compound, will be described.
The degradable compound may be a compound that absorbs and decomposes at least one part of light in the infrared wavelength range (wavelength range of 750 nm to 1 mm, preferably wavelength range of 750 nm to 1,400 nm), and may be 750 nm to 1, It is preferably a compound having maximum absorption in the wavelength range of 400 nm.
More specifically, the degradable compound is preferably a compound that decomposes due to infrared exposure to produce a compound having a maximum absorption wavelength in the wavelength range of 500 nm to 600 nm.

The degradable compound is preferably a cyanine dye having a ^{group (specifically, R 1} in the following formulas 1-1 to 1-7) that decomposes by infrared exposure from the viewpoint of enhancing the visibility of the exposed portion. ..
The degradable compound is more preferably a compound represented by the following formula 1-1 from the viewpoint of enhancing the visibility of the exposed portion.

In formula 1-1, R ¹ represents a group represented by any of the following formulas 2 to 4, and R ^{11 to} R ¹⁸ independently represent a hydrogen atom, a halogen atom, -R ^a , -OR ^b , and so on. -SR ^c, or represents ^{-NR d R e, R a ~R} e each independently represent a hydrocarbon _group, a 1, _{a 2} and a plurality of _R 11 _{to R 18} are linked to monocyclic Alternatively, a polycycle may be formed, where A ₁ and A ₂ independently represent an oxygen atom, a sulfur atom, or a nitrogen atom, and n ₁₁ and n ₁₂ are independently integers of 0 to 5, respectively. However, _{the sum of n 11} and n ₁₂ is 2 or more, n ₁₃ and n ₁₄ independently represent 0 or 1, and L represents an oxygen atom, a sulfur atom, or −NR ¹⁰ −. ^{Representing R 10} , represents a hydrogen atom, an alkyl group, or an aryl group, and Za represents a counterion that neutralizes the charge.

In Formulas 2 to 4, R ²⁰ , R ³⁰ , R ⁴¹ and R ⁴² independently represent an alkyl group or an aryl group, Zb represents a counterion that neutralizes the charge, and the wavy line represents the above formula 1-. Represents a binding site with a group represented by L in 1.

Compounds of the formula 1-1, when exposed with ^{infrared, R} 1 -L bond is cleaved, L is, = O, = S, or = become ^{NR 10,} changes color.

In formula 1-1, R ¹ represents a group represented by any of the above formulas 2 to 4.
Hereinafter, the group represented by the formula 2, the group represented by the formula 3, and the group represented by the formula 4 will be described.

In formula 2, R ²⁰ represents an alkyl group or an aryl group, and the wavy line portion represents a binding site with a group represented by L in formula 1-1.
As the ^{alkyl group represented by R 20} , an alkyl group having 1 to 30 carbon atoms is preferable, an alkyl group having 1 to 15 carbon atoms is more preferable, and an alkyl group having 1 to 10 carbon atoms is further preferable.
The alkyl group may be linear, have a branch, or have a ring structure.
As the ^{aryl group represented by R 20} , an aryl group having 6 to 30 carbon atoms is preferable, an aryl group having 6 to 20 carbon atoms is more preferable, and an aryl group having 6 to 12 carbon atoms is further preferable.
The R ²⁰ is preferably an alkyl group from the viewpoint of color development.

Moreover, degradable, and, from the viewpoint of coloring properties, be the alkyl group represented by R ^20, is preferably a secondary alkyl group or a tertiary alkyl group, tertiary alkyl group preferable.
Moreover, the degradability, and, from the viewpoint of coloring properties, the alkyl group represented by R ^20, preferably an alkyl group having 1 to 8 carbon atoms, branched alkyl group having 3 to 10 carbon atoms It is more preferable to have a branched alkyl group having 3 to 6 carbon atoms, an isopropyl group or a tert-butyl group is particularly preferable, and a tert-butyl group is most preferable.
Here, the ^{alkyl group represented by R 20} may be a substituted alkyl group substituted with a halogen atom (for example, a chloro group) or the like.

Specific examples of the group represented by the above formula 2 will be given below, but the present disclosure is not limited thereto. In the following structural formula, ● represents the binding site with the group represented by L in the formula 1-1.

In formula 3, R ³⁰ represents an alkyl group or an aryl group, and the wavy line portion represents a binding site with a group represented by L in formula 1-1.
The ^{alkyl group and aryl group represented by R 30} are the same as those of the alkyl group and aryl group ^{represented by R 20} in Formula 2, and the preferred embodiments are also the same.

Degradable, and, from the viewpoint of coloring properties, the alkyl group represented by R ^30, preferably a is secondary alkyl group or a tertiary alkyl group is preferably a tertiary alkyl group.
Moreover, degradable, and, from the viewpoint of coloring properties, the alkyl group represented by R ^30, preferably an alkyl group having 1 to 8 carbon atoms, branched alkyl group having 3 to 10 carbon atoms It is more preferable to have a branched alkyl group having 3 to 6 carbon atoms, an isopropyl group or a tert-butyl group is particularly preferable, and a tert-butyl group is most preferable.
Furthermore, biodegradable, and, from the viewpoint of chromogenic, alkyl groups represented by R ³⁰ is preferably a substituted alkyl group, more preferably a fluoro-substituted alkyl group, a perfluoroalkyl group Is more preferable, and a trifluoromethyl group is particularly preferable.

From the viewpoint of degradability and color development, the ^{aryl group represented by R 30} is preferably a substituted aryl group, and the substituent is an alkyl group (preferably an alkyl group having 1 to 4 carbon atoms) or an alkoxy. Examples thereof include a group (preferably an alkoxy group having 1 to 4 carbon atoms).

Specific examples of the group represented by the above formula 3 are given below, but the present disclosure is not limited thereto. In the following structural formula, ● represents the binding site with the group represented by L in the formula 1-1.

In Formula 4, R ⁴¹ and R ⁴² independently represent an alkyl or aryl group, Zb represents a charge-neutralizing counterion, and the wavy line portion is a group represented by L in Formula 1-1. Represents the binding site with.
The ^{alkyl group and aryl group represented by R 41} or R ⁴² are the same as those of the alkyl group and aryl group ^{represented by R 20} in the formula 2, and the preferred embodiments are also the same.
The R ⁴¹ is preferably an alkyl group from the viewpoint of degradability and color development.
The R ⁴² is preferably an alkyl group from the viewpoint of degradability and color development.

From the viewpoint of decomposability and color development, the ^{alkyl group represented by R 41} is preferably an alkyl group having 1 to 8 carbon atoms, and more preferably an alkyl group having 1 to 4 carbon atoms. , Methyl group is particularly preferred.
From the viewpoint of decomposability and color development, the ^{alkyl group represented by R 42} is preferably a secondary alkyl group or a tertiary alkyl group, and preferably a tertiary alkyl group.
Further, from the viewpoint of degradability and color development, the ^{alkyl group represented by R 42} is preferably an alkyl group having 1 to 8 carbon atoms, and is a branched alkyl group having 3 to 10 carbon atoms. It is more preferable to have a branched alkyl group having 3 to 6 carbon atoms, an isopropyl group or a tert-butyl group is particularly preferable, and a tert-butyl group is most preferable.

Zb in the formula 4 may be a counterion for neutralizing the charge, and the compound as a whole may be contained in Za in the formula 1-1.
Zb is preferably a sulfonate ion, a carboxylate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, a p-toluenesulfonate ion, or a perchlorate ion, and more preferably a tetrafluoroborate ion.

Specific examples of the group represented by the above formula 4 are given below, but the present disclosure is not limited thereto. In the following structural formula, ● represents the binding site with the group represented by L in the formula 1-1.

In the formula 1-1, L is ^{preferably an oxygen atom or −NR 10} −, and an oxygen atom is particularly preferable.
Further, R ^{10 in −NR 10} − is preferably an alkyl group. As the ^{alkyl group represented by R 10} , an alkyl group having 1 to 10 carbon atoms is preferable. Further, the ^{alkyl group represented by R 10} may be linear, may have a branch, or may have a ring structure.
Among the alkyl groups, a methyl group or a cyclohexyl group is preferable.
When R ^{10 in −NR 10} − is an aryl group, an aryl group having 6 to 30 carbon atoms is preferable, an aryl group having 6 to 20 carbon atoms is more preferable, and an aryl group having 6 to 12 carbon atoms is further preferable. Moreover, these aryl groups may have a substituent.

In Formula ^1-1, R 11 ^{to R 18} each independently represents a hydrogen ^atom, -R ^a, is preferably -OR b, -SR ^c, or ^-NR d ^{R e.}
Hydrocarbon groups represented by R ^a to R ^e is preferably a hydrocarbon group having 1 to 30 carbon atoms, more preferably a hydrocarbon group having 1 to 15 carbon atoms, further a hydrocarbon group having 1 to 10 carbon atoms preferable.
The hydrocarbon group may be linear, may have a branch, or may have a ring structure.
As the hydrocarbon group, an alkyl group is particularly preferable.

As the alkyl group, an alkyl group having 1 to 30 carbon atoms is preferable, an alkyl group having 1 to 15 carbon atoms is more preferable, and an alkyl group having 1 to 10 carbon atoms is further preferable.
The alkyl group may be linear, have a branch, or have a ring structure.
Specifically, for example, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, a hexadecyl group and an octadecyl group. Group, eicosyl group, isopropyl group, isobutyl group, s-butyl group, tert-butyl group, isopentyl group, neopentyl group, 1-methylbutyl group, isohexyl group, 2-ethylhexyl group, 2-methylhexyl group, cyclohexyl group, cyclopentyl Examples include a group and a 2-norbornyl group.
Among the alkyl groups, a methyl group, an ethyl group, a propyl group or a butyl group is preferable.

The alkyl group may have a substituent.
Examples of substituents include an alkoxy group, an aryloxy group, an amino group, an alkylthio group, an arylthio group, a halogen atom, a carboxy group, a carboxylate group, a sulfo group, a sulfonate group, an alkyloxycarbonyl group, an aryloxycarbonyl group, and these. Examples include a group that combines the above.

^{R 11 to} R ¹⁴ in the formula 1-1 are each independently ^{preferably a hydrogen atom or −R a} (that is, a hydrocarbon group), more preferably a hydrogen atom or an alkyl group, and the following. Except for the case of, it is more preferably a hydrogen atom.
^{Among them, R 11} and R ¹³ bonded to the carbon atom to which L is bonded are preferably an alkyl group, and it is more preferable that both are linked to form a ring. The ring formed may be a monocyclic ring or a polycyclic ring. Specific examples of the ring formed include a monocycle such as a cyclopentene ring, a cyclopentadiene ring, a cyclohexene ring and a cyclohexadiene ring, and a polycycle such as an indene ring and an indole ring.
Further, ^{it is preferable that R 12} bonded to the carbon atom to which _{A 1} ⁺ is bonded is linked to R ¹⁵ or R ¹⁶ (preferably R ¹⁶ ) to form a ring, and R to be bonded to the carbon atom to which _{A 2 is bonded.} ¹⁴ is ^{preferably linked to R 17} or R ¹⁸ (preferably R ¹⁸ ) to form a ring.

In the formula 1-1, n ₁₃ is preferably 1 and R ¹⁶ is ^{preferably −R a} (that is, a hydrocarbon group).
Further, ^{it is preferable that R 16} is ^{linked to R 12} bonded to the carbon atom to which _{A 1} ⁺ is bonded to form a ring. As the ring to be formed, an indolium ring, a pyrylium ring, a thiopyrylium ring, a benzoxazoline ring, or a benzoimidazoline ring is preferable, and an indolium ring is more preferable from the viewpoint of enhancing the visibility of the exposed portion. These rings may further have a substituent.
In formula 1-1, n ₁₄ is preferably 1 and R ¹⁸ is ^{preferably −R a} (ie, a hydrocarbon group).
Further, ^{it is preferable that R 18} is ^{linked to R 14} bonded to the carbon atom to which _{A 2} is bonded to form a ring. As the ring to be formed, an indole ring, a pyran ring, a thiopyran ring, a benzoxazole ring, or a benzimidazole ring is preferable, and an indole ring is more preferable from the viewpoint of enhancing the visibility of the exposed portion. These rings may further have a substituent.
^{It is preferable that R 16} and R ¹⁸ in the formula 1-1 have the same group, and when each forms a ring, it is preferable to form a ring having the same structure except for _{A 1} ⁺ and A _2.

^{It is preferable that R 15} and R ¹⁷ in the formula 1-1 are the same group. Further, R ¹⁵ and R ¹⁷ are preferably —R ^a (that is, a hydrocarbon group), more preferably an alkyl group, and even more preferably a substituted alkyl group.

In the compound represented by the formula 1-1, R ¹⁵ and R ¹⁷ are preferably substituent alkyl groups from the viewpoint of improving water solubility.
Examples of the substituted alkyl group represented by R ¹⁵ or R ¹⁷ include a group represented by any of the following formulas (a1) to (a4).

Wherein (a1) ~ formula ^{(a4), R W0} represents an alkylene group having 2 to 6 carbon atoms, W is a single bond or an oxygen _{atom, n W1} represents an integer of 1 to ^{45, R W1} carbon It represents the number 1 to 12 alkyl or ^{-C (= O) -R W5,} R W5 represents an alkyl group having 1 to 12 carbon ^atoms, R W2 ^{to R W4} are each independently a single bond or 1 carbon atoms Represents an alkylene group of ~ 12, and M represents a hydrogen atom, a sodium atom, a potassium atom, or an onium group.

^{Specific examples of the alkylene group represented by RW0} in the formula (a1) include an ethylene group, an n-propylene group, an isopropylene group, an n-butylene group, an isobutylene group, an n-pentylene group, an isopentylene group and n-. Examples thereof include a hexyl group and an isohexyl group, and an ethylene group, an n-propylene group, an isopropylene group, or an n-butylene group is preferable, and an n-propylene group is particularly preferable.
n _W1 is preferably 1 to 10, more preferably 1 to 5, and particularly preferably 1 to 3.
^{Specific examples of the alkyl group represented by RW1} include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, n-pentyl group, isopentyl group and neopentyl. Examples thereof include a group, an n-hexyl group, an n-octyl group, an n-dodecyl group, and a methyl group, an ethyl group, an n-propyl group, an isopropyl group, or an n-butyl group and a tert-butyl group are preferable. , Or an ethyl group is more preferable, and a methyl group is particularly preferable.
Alkyl group represented by R ^W5 is the same as defined for the alkyl group represented by R ^W1, preferred embodiments are also the same as the preferred embodiment of the alkyl group represented by R ^W1.

Specific examples of the group represented by the formula (a1) are shown below, but the present disclosure is not limited thereto. In the following structural formula, Me represents a methyl group, Et represents an ethyl group, and * represents a binding site.

In formula (a2) ~ formula ^(a4), Specific examples of the alkylene group represented by R W2 ^{to R W4,} methylene group, ethylene group, n- propylene, isopropylene, n- butylene group, isobutylene group , N-pentylene group, isopentylene group, n-hexyl group, isohexyl group, n-octylene group, n-dodecylene group and the like, and ethylene group, n-propylene group, isopropylene group or n-butylene group An ethylene group or an n-propylene group is particularly preferable.
In the formula (a3), the two existing Ms may be the same or different.

In the formulas (a2) to (a4), examples of the onium group represented by M include an ammonium group, an iodonium group, a phosphonium group, a sulfonium group, and the like.
The CO ₂ M in the formula (a 2), the PO ₃ M _{2 in the formula (a 2), and the SO 3} M in the formula (a 4) may all have an anion structure in which M is dissociated. Counter cation of the anion structure may be a A ₁ ^+, may be a cation may be included in R ¹ -L in Formula 1-1.

Among the groups represented by the formulas (a1) to (a4), the group represented by the formula (a1), the formula (a2), or the formula (a4) is preferable.

_{It is preferable that n 11} and n ₁₂ in the formula 1-1 are the same, and an integer of 1 to 5 is preferable, an integer of 1 to 3 is more preferable, 1 or 2 is more preferable, and 2 is particularly preferable.

_{A 1} and A ₂ in the formula 1-1 independently represent an oxygen atom, a sulfur atom, or a nitrogen atom, and a nitrogen atom is preferable.
_{It is preferable that A 1} and A ₂ in the formula 1-1 are the same atom.

Za in Equation 1-1 represents a counterion that neutralizes the charge.
If all of R ^{11 to} R ¹⁸ and R ^1- L are charge-neutral groups, Za is a monovalent counter anion. However, R ^{11 to} R ¹⁸ and R ^{1 to} L may have an anionic structure or a cationic structure. For example, when R ^{11 to} R ¹⁸ and R ^{1 to} L have two or more anionic structures, Za Can also be a counter cation.
If the cyanine dye represented by the formula 1-1 has a charge-neutral structure in the whole compound except Za, Za is not necessary.
When Za is a counter anion, sulfonate ion, carboxylate ion, tetrafluoroborate ion, hexafluorophosphate ion, p-toluenesulfonate ion, perchlorate ion and the like can be mentioned, and tetrafluoroborate ion is preferable.
When Za is a counter cation, alkali metal ion, alkaline earth metal ion, ammonium ion, pyridinium ion, sulfonium ion and the like can be mentioned, and sodium ion, potassium ion, ammonium ion, pyridinium ion or sulfonium ion is preferable. Ions, potassium ions, or ammonium ions are more preferred.

The degradable compound is more preferably a compound represented by the following formula 1-2 (that is, a cyanine dye) from the viewpoint of enhancing the visibility of the exposed portion.

In formula 1-2, R ¹ represents a group represented by any of the above formulas 2 to 4, and R ^{19 to} R ²² are independently hydrogen atom, halogen atom, -R ^a , -OR ^b , respectively. -CN, -SR ^c , or -NR ^d R ^e , R ²³ and R ^{24 independently represent a} hydrogen atom or -R a, and R ^{a to} R ^e independently represent a hydrocarbon group. , R ¹⁹ and R ²⁰ , R ²¹ and R ²² , or R ²³ and R ²⁴ may be linked to form a monocyclic or polycyclic, where L is an oxygen atom, a sulfur atom, or. -NR ^10- represents, R ¹⁰ represents a hydrogen atom, an alkyl group, or an aryl group, and R ^{d1 to} R ^d4 , W ¹ and W ² each independently may have a substituent. Represents, and Za represents a counter ion that neutralizes the charge.

^{R 1} in Formula 1-2 is synonymous with ^{R 1} in the formula 1-1, preferable embodiments thereof are also the same.

In formula 1-2, R ^{19 to} R ²² are preferably hydrogen atoms, halogen atoms, -R ^a , -OR ^b , or -CN, respectively.
More ^{specifically, R 19} and ^{R 21} are preferably hydrogen atom, or a -R ^a.
Further, R ²⁰ and R ²² are preferably hydrogen atoms, -R ^a , -OR ^b , or -CN.
As ^{—R a} represented by ^{R 19 to} R ²² , an alkyl group or an alkenyl group is preferable.
When all of ^{R 19 to} R ^{22 are −R a,} it is preferable that R ¹⁹ and R ²⁰ and R ²¹ and R ²² are connected to form a monocyclic or polycyclic ring.
Examples of the ring formed by connecting R ¹⁹ and R ²⁰ or R ²¹ and R ²² include a benzene ring and a naphthalene ring.

In formula 1-2, ^{it is preferable that R 23} and R ²⁴ are connected to form a monocyclic or polycyclic ring.
The ^{ring formed by connecting R 23} and R ²⁴ may be a monocyclic ring or a polycyclic ring. Specific examples of the ring formed include a monocycle such as a cyclopentene ring, a cyclopentadiene ring, a cyclohexene ring and a cyclohexadiene ring, and a polycycle such as an inden ring.

In formula 1-2, R ^{d1 to} R ^d4 are preferably unsubstituted alkyl groups. Further, ^{it is preferable that R d1 to} R ^d4 are all the same group.
Examples of the unsubstituted alkyl group include an unsubstituted alkyl group having 1 to 4 carbon atoms, and a methyl group is preferable.

In formula 1-2, W ¹ and W ² are preferably substituted alkyl groups independently from the viewpoint of increasing water solubility in the compound represented by formula 1-2.
Examples of the ^{substituted alkyl group represented by W 1} and W ² include a group represented by any of the formulas (a1) to (a4) in the formula 1-1, and the preferred embodiment is also the same.
Further, W ¹ and W ² are independently alkyl groups having a substituent from the viewpoint of on-machine developability, and the above-mentioned substituents are-(OCH ₂ CH ₂ )-, a sulfo group, and a sulfo group. , A carboxy group, or a group having at least a salt of a carboxy group is preferable.

Za represents a counterion that neutralizes the charge in the molecule.
If all of R ^{19 to} R ²² , R ^{23 to} R ²⁴ , R ^{d1 to} R ^d4 , W ¹ , W ² , and R ^{1 to} L are charge-neutral groups, then Za is a monovalent pair. It becomes an anion. However, R ^{19 to} R ²² , R ^{23 to} R ²⁴ , R ^{d1 to} R ^d4 , W ¹ , W ² , and R ^{1 to} L may have an anionic structure or a cationic structure, for example, R. ^{If 19 to} R ²² , R ^{23 to} R ²⁴ , R ^{d1 to} R ^d4 , W ¹ , W ² , and R ^{1 to} L have two or more anionic structures, Za can also be a counter cation.
If the compound represented by the formula 1-2 has a charge-neutral structure as a whole except for Za, Za is not necessary.
The example when Za is a counter anion is the same as Za in the formula 1-1, and the preferred embodiment is also the same. Further, the example in which Za is a counter cation is the same as Za in Formula 1-1, and the preferred embodiment is also the same.

The cyanine dye as a degradable compound is more preferably a compound represented by any of the following formulas 1-3 to 1-7 from the viewpoint of decomposability and color development.
In particular, from the viewpoint of degradability and color development, the compound represented by any of the formulas 1-3, 1-5, and 1-6 is preferable.

In formulas 1-3 to 1-7, R ¹ represents a group represented by any of the above formulas 2 to 4, and R ^{19 to} R ²² are independently hydrogen atom, halogen atom, and −R ^a. , ^-OR b, -CN, -SR ^c, or represents ^-NR d ^{R e,} each ^{R 25} and ^{R 26} independently represent a hydrogen atom, a halogen atom, or represents a -R ^a, R a to R ^e independently represent a hydrocarbon group, and R ¹⁹ and R ²⁰ , R ²¹ and R ²² , or R ²⁵ and R ²⁶ may be linked to form a monocyclic or polycyclic, where L is. , Oxygen atom, sulfur atom, or −NR ¹⁰⁻ , R ¹⁰ represents a hydrogen atom, an alkyl group, or an aryl group, and R ^{d1 to} R ^d4 , W ¹ and W ² are independent of each other. Represents an alkyl group that may have a substituent, and Za represents a counterion that neutralizes the charge.

^{R 1, R 19 ~R 22} in Formula 1-3 to Formula ^{1-7, R d1 ~R d4, W} 1, W 2, and L is, ^R 1 in Formula ^{1-2, R 19 ~R 22,} R ^{d1 ~R d4, W 1, W} 2, and has the same meaning as L, and also the same preferred embodiment.
^{R 25} and R ²⁶ in Formula 1-7 are each independently preferably a hydrogen atom or an alkyl group, more preferably an alkyl group, and particularly preferably a methyl group.

Specific examples of cyanine pigments of degradable compounds are given below, but the present disclosure is not limited thereto.

Further, as the cyanine dye which is a degradable compound, the infrared absorbent compound described in International Publication No. 2019/219560 can be preferably used.

Moreover, you may use an acid color former as a discolorant compound.
As the acid color-developing agent, those described as the acid color-developing agent in the image recording layer can be used, and the preferred embodiment is also the same.

The discolorating compound may be used alone or in combination of two or more kinds of components.
As the discolorating compound, the acid color-developing agent described above and the acid generator described later may be used in combination.

The content of the discolorating compound in the outermost layer is preferably 0.10% by mass to 50% by mass, more preferably 0.50% by mass to 30% by mass, based on the total mass of the outermost layer from the viewpoint of color development. , 1.0% by mass to 20% by mass is more preferable.

The ratio M ^{X /} M ^Y between the content M ^Y of the infrared absorber content M ^X and the image recording layer of the discoloring compounds of the outermost layer, from the viewpoints of coloring property, is 0.1 or more It is preferable, 0.2 or more is more preferable, and 0.3 or more and 3.0 or less is particularly preferable.

[Other ingredients]
In addition to the inorganic layered compound and the discoloring compound, the outermost layer may contain other components such as a water-soluble polymer, a hydrophobic polymer, a fat-sensing agent, an acid generator, and an infrared absorber other than the discoloring compound. good.
Hereinafter, other components will be described.

[Water-soluble polymer]
The outermost layer preferably contains a water-soluble polymer from the viewpoint of on-machine developability.
In the present disclosure, the water-soluble polymer is a solution in which 5 g or more is dissolved in 100 g of pure water at 125 ° C. and 5 g of the polymer is dissolved in 125 ° C. and 100 g of pure water, and the solution is cooled to 25 ° C. A polymer that does not precipitate even if it does.
Examples of the water-soluble polymer used for the outermost layer include polyvinyl alcohol, modified polyvinyl alcohol, polyvinylpyrrolidone, water-soluble cellulose derivative, polyethylene glycol, poly (meth) acrylonitrile and the like.
As the modified polyvinyl alcohol, an acid-modified polyvinyl alcohol having a carboxy group or a sulfo group is preferably used. Specific examples thereof include the modified polyvinyl alcohols described in JP-A-2005-250216 and JP-A-2006-259137.

As the water-soluble polymer, polyvinyl alcohol is preferable. Above all, as the water-soluble polymer, it is more preferable to use polyvinyl alcohol having a saponification degree of 50% or more.
The saponification degree is preferably 60% or more, more preferably 70% or more, still more preferably 85% or more. The upper limit of the saponification degree is not particularly limited and may be 100% or less.
The saponification degree is measured according to the method described in JIS K 6726: 1994.

As the water-soluble polymer, polyvinylpyrrolidone is also preferable.
As the hydrophilic polymer, it is also preferable to use polyvinyl alcohol and polyvinylpyrrolidone in combination.

The water-soluble polymer may be used alone or in combination of two or more.

When the outermost layer contains a water-soluble polymer, the content of the water-soluble polymer is preferably 1% by mass to 99% by mass, preferably 3% by mass to 97% by mass, based on the total mass of the outermost layer. Is more preferable, and 5% by mass to 95% by mass is further preferable.

[Hydrophobic polymer]
The outermost layer may contain a hydrophobic polymer.
The hydrophobic polymer means a polymer that dissolves or does not dissolve in less than 5 g in 100 g of pure water at 125 ° C.
Examples of the hydrophobic polymer include polyethylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, and poly (meth) acrylate alkyl esters (for example, poly (meth) acrylate methyl, poly (meth) acrylate ethyl, and poly (meth). ) Butyl acrylate, etc.), copolymers in which raw material monomers of these polymers are combined, and the like.
Further, the hydrophobic polymer preferably contains polyvinylidene chloride resin.
Further, the hydrophobic polymer preferably contains a styrene-acrylic copolymer.

Furthermore, the hydrophobic polymer is preferably hydrophobic polymer particles from the viewpoint of on-machine developability.

The hydrophobic polymer may be used alone or in combination of two or more.

When the outermost layer contains a hydrophobic polymer, the content of the hydrophobic polymer is preferably 1% by mass to 80% by mass and 5% by mass to 50% by mass with respect to the total mass of the outermost layer. Is more preferable.

[Fat sensitive agent]
The outermost layer may contain a greasing agent from the viewpoint of ink inking property.
As the oil-sensitive agent used for the outermost layer, the oil-sensitive agent described in the above-mentioned image recording layer can be used, and the preferred embodiment is also the same.

The oil sensitizer may be used alone or in combination of two or more.
When the outermost layer contains a fat-sensing agent, the content of the fat-sensing agent is preferably 0.5% by mass to 30% by mass, and 1% by mass to 20% by mass, based on the total mass of the outermost layer. % Is more preferable.

[Acid generator]
When an acid color-developing agent is used as the discolorating compound, the outermost layer preferably contains an acid generator.
The "acid generator" in the present disclosure is a compound that generates an acid by light or heat, and specifically, a compound that is decomposed by infrared exposure to generate an acid.
The acid to be generated is preferably a strong acid having a pKa of 2 or less, such as sulfonic acid and hydrochloric acid. The acid generated from the acid generator can discolor the above-mentioned acid color former.

Specifically, the onium salt compound is preferable as the acid generator from the viewpoint of sensitivity and stability.
Specific examples of the onium salt suitable as the acid generator include the compounds described in paragraphs 0121 to 0124 of International Publication No. 2016/047392.
Among them, triarylsulfonium, or diaryliodonium, sulfonates, _{^{carboxylates, BPh 4 -, BF 4 -}} , PF 6 -, ClO 4 - and the like are preferable. Here, Ph represents a phenyl group.

The acid generator may be used alone or in combination of two or more.
When the outermost layer contains an acid generator, the content of the acid generator is preferably 0.5% by mass to 30% by mass, preferably 1% by mass to 20% by mass, based on the total mass of the outermost layer. It is more preferable to have.

In addition to the above-mentioned components, the outermost layer is a known additive such as a plasticizer for imparting flexibility, a surfactant for improving coatability, and inorganic particles for controlling the slipperiness of the surface. May include.

The outermost layer is formed by being applied by a known method and dried.
Outermost coating amount (solid content) is ^preferably from ^{0.01g / m 2 ~10g / m 2} , more preferably ^{0.02g / m 2 ~3g / m 2} , 0.1g / m 2 ~2.0g / M ² is particularly preferred.
The film thickness of the outermost layer is preferably 0.1 μm to 5.0 μm, and more preferably 0.3 μm to 4.0 μm.

The film thickness of the outermost layer is preferably 0.1 to 5.0 times, more preferably 0.2 to 3.0 times, the film thickness of the image recording layer described later.

<Support>
The lithographic printing plate original plate according to the present disclosure has a support.
As the support, a known lithographic printing plate precursor support can be appropriately selected and used.
As the support, a support having a hydrophilic surface (hereinafter, also referred to as “hydrophilic support”) is preferable.

As the support in the present disclosure, an aluminum plate that has been roughened and anodized by a known method is preferable. That is, the support in the present disclosure preferably has an aluminum plate and an aluminum anodized film arranged on the aluminum plate.

[Preferable embodiment of support]
An example of a preferred embodiment of the support used in the present disclosure (the aluminum support according to this example is also referred to as “support (1)”) is shown below.
That is, the support (1) has an aluminum plate and an anodic oxide film of aluminum arranged on the aluminum plate, and the anodic oxide film is located closer to the image recording layer than the aluminum plate. The anodic oxide film has micropores extending in the depth direction from the surface on the image recording layer side, and the average diameter of the micropores on the surface of the anodic oxide film is more than 10 nm and 100 nm or less.
The value of the brightness L ^{* in the L *} a ^* b ^* color system of the surface of the anodic oxide film on the image recording layer side is preferably 70 to 100.

FIG. 1 is a schematic cross-sectional view of an embodiment of the aluminum support 12a.
The aluminum support 12a has a laminated structure in which an aluminum plate 18 and an aluminum anodic oxide film 20a (hereinafter, also simply referred to as “anodized film 20a”) are laminated in this order. The anodic oxide film 20a in the aluminum support 12a is located closer to the image recording layer than the aluminum plate 18. That is, it is preferable that the lithographic printing plate original plate according to the present disclosure has at least an anodic oxide film, an image recording layer, and a water-soluble resin layer on an aluminum plate in this order.

-Anodic oxide film-
Hereinafter, preferred embodiments of the anodic oxide film 20a will be described.
The anodic oxide film 20a is a film formed on the surface of the aluminum plate 18 by anodization treatment, and this film is substantially perpendicular to the surface of the film and has ultrafine micropores 22a in which each is uniformly distributed. Has. The micropore 22a extends from the surface of the anodic oxide film 20a on the image recording layer side (the surface of the anodic oxide film 20a on the side opposite to the aluminum plate 18 side) along the thickness direction (aluminum plate 18 side).

The average diameter (average opening diameter) of the micropores 22a in the anodic oxide film 20a on the surface of the anodic oxide film is preferably more than 10 nm and 100 nm or less. Among them, from the viewpoint of the balance between printing resistance, stain resistance, and image visibility, 15 nm to 60 nm is more preferable, 20 nm to 50 nm is further preferable, and 25 to 40 nm is particularly preferable. The diameter inside the pores may be wider or narrower than the surface layer.
When the average diameter exceeds 10 nm, the printing durability and the image visibility are further excellent. Further, when the average diameter is 100 nm or less, the printing durability is further excellent.
The average diameter of the micropores 22a is 400 nm × 600 nm in the obtained 4 images obtained by observing the surface of the anodized film 20a with a field emission scanning electron microscope (FE-SEM) at a magnification of 150,000 times. The diameter (diameter) of the micropores existing in the range of is measured at 50 points and calculated as an arithmetic average value.
If the shape of the micropore 22a is not circular, the diameter equivalent to the circle is used. The "circle equivalent diameter" is the diameter of a circle when the shape of the opening is assumed to be a circle having the same projected area as the projected area of the opening.

The depth of the micropore 22a is not particularly limited, but is preferably 10 nm to 3,000 nm, more preferably 50 nm to 2,000 nm, and even more preferably 300 nm to 1,600 nm.
The depth is an average value obtained by taking a photograph (150,000 times) of a cross section of the anodic oxide film 20a and measuring the depths of 25 or more micropores 22a.

The shape of the micropore 22a is not particularly limited, and in FIG. 2, it is a substantially straight tubular (substantially cylindrical) shape, but may be a conical shape whose diameter decreases in the depth direction (thickness direction). Further, the shape of the bottom portion of the micropore 22a is not particularly limited, and may be curved (convex) or planar.

^{The value of L *} a ^* b ^{* lightness L *} in the color system of the surface of the aluminum support 12a on the image recording layer side (the surface of the anodic oxide film 20a on the image recording layer side) is preferably 70 to 100. .. Among them, 75 to 100 is preferable, and 75 to 90 is more preferable, in that the balance between printing durability and image visibility is more excellent.
The brightness L ^* is measured using a color difference meter SpecroEye manufactured by X-Rite Co., Ltd.

In the support (1), the micropore communicates with the large-diameter hole extending from the surface of the anodic oxide film to a depth of 10 nm to 1,000 nm and the bottom of the large-diameter hole, and is deep from the communication position. It is composed of a small-diameter hole extending from 20 nm to 2,000 nm, and the average diameter of the large-diameter hole on the surface of the anodic oxide film is 15 nm to 100 nm, and the average diameter of the small-diameter hole at the communication position. A mode in which the diameter is 13 nm or less (hereinafter, the support according to this mode is also referred to as “support (2)”) is also preferably mentioned.
FIG. 2 is a schematic cross-sectional view of the aluminum support 12a according to an embodiment different from that shown in FIG.
In FIG. 2, the aluminum support 12b includes an aluminum plate 18 and an anodic oxide film 20b having a micropore 22b composed of a large-diameter hole portion 24 and a small-diameter hole portion 26.
The micropores 22b in the anodic oxide film 20b have a large-diameter hole portion 24 extending from the surface of the anodic oxide film to a depth of 10 nm to 1,000 nm (depth D: see FIG. 2) and a bottom portion of the large-diameter hole portion 24. It is composed of a small-diameter hole portion 26 extending from the communication position to a depth of 20 nm to 2,000 nm.
The details of the large-diameter hole portion 24 and the small-diameter hole portion 26 are as described in paragraphs 0107 to 0114 of Japanese Patent Application Laid-Open No. 2019-162855, and this aspect is also applied in the present disclosure.

[Manufacturing method of aluminum support]
As the method for manufacturing the aluminum support in the present disclosure, for example, a manufacturing method in which the following steps are sequentially performed is preferable.
・ Roughening treatment step: Roughening treatment of aluminum plate ・ Anodizing treatment step: Anodizing the roughened aluminum plate ・ Pore wide treatment step: Anodizing obtained in the anodic oxidation treatment step Step of bringing an aluminum plate having an oxide film into contact with an acid aqueous solution or an alkaline aqueous solution to increase the diameter of micropores in the anodized film The procedure of each step will be described in detail below.

(Roughening process)
The roughening treatment step is a step of applying a roughening treatment including an electrochemical roughening treatment to the surface of the aluminum plate. This step is preferably carried out before the anodizing treatment step described later, but it may not be carried out in particular as long as the surface of the aluminum plate already has a preferable surface shape.
The roughening treatment for the aluminum plate can be performed by the method described in paragraphs 0086 to 0101 of JP-A-2019-162855.

(Anodizing process)
The procedure of the anodic oxidation treatment step is not particularly limited as long as the above-mentioned micropores can be obtained, and a known method can be mentioned.
In the anodizing treatment step, an aqueous solution of sulfuric acid, phosphoric acid, oxalic acid or the like can be used as the electrolytic bath. For example, the concentration of sulfuric acid may be 100 g / L to 300 g / L.
The conditions for the anodizing treatment are appropriately set depending on the electrolytic solution used, and for example, the liquid temperature is 5 ° C to 70 ° C (preferably 10 ° C to 60 ° C), and the current density is 0.5 A / dm ^{2 to} 60 A / dm ^2. (Preferably 5A / dm ^{2 to} 60A / dm ² ), voltage 1V to 100V (preferably 5V to 50V), electrolysis time 1 to 100 seconds (preferably 5 to 60 seconds), and film amount 0.1 g. / ^{M 2 to} 5 g / m ² (preferably 0.2 g / m ^{2 to} 3 g / m ² ).

(Pore wide processing)
The pore wide treatment is a treatment (pore diameter expansion treatment) for enlarging the diameter (pore diameter) of the micropores existing in the anodic oxide film formed by the above-mentioned anodizing treatment step.
The pore-wide treatment can be performed by contacting the aluminum plate obtained by the above-mentioned anodizing treatment step with an acid aqueous solution or an alkaline aqueous solution. The contact method is not particularly limited, and examples thereof include a dipping method and a spraying method.

<Undercoat layer>
The lithographic printing plate original plate according to the present disclosure preferably has an undercoat layer (sometimes referred to as an intermediate layer) between the image recording layer and the support. The undercoat layer strengthens the adhesion between the support and the image recording layer in the exposed portion, and facilitates peeling of the image recording layer from the support in the unexposed portion, so that the deterioration of printing durability is suppressed. Contributes to improving developability. Further, in the case of infrared laser exposure, the undercoat layer functions as a heat insulating layer, which also has an effect of preventing the heat generated by the exposure from diffusing to the support and reducing the sensitivity.

〔polymer〕
Examples of the compound used for the undercoat layer include polymers having an adsorptive group and a hydrophilic group that can be adsorbed on the surface of the support. In order to improve the adhesion to the image recording layer, a polymer having an adsorptive group and a hydrophilic group and further having a crosslinkable group is preferable. The compound used for the undercoat layer may be a low molecular weight compound or a polymer. As the compound used for the undercoat layer, two or more kinds may be mixed and used as needed.

When the compound used for the undercoat layer is a polymer, a copolymer of a monomer having an adsorptive group, a monomer having a hydrophilic group and a monomer having a crosslinkable group is preferable.
Adsorbable groups that can be adsorbed on the surface of the support include phenolic hydroxy groups, carboxy groups, -PO ₃ H ₂ , -OPO ₃ H ₂ , -CONHSO _2- , -SO ₂ NHSO _2- , _{-COCH 2} COCH ₃ Is preferable. As the hydrophilic group, a sulfo group or a salt thereof, or a salt of a carboxy group is preferable. As the crosslinkable group, an acrylic group, a methacryl group, an acrylamide group, a methacrylamide group, an allyl group and the like are preferable.
The polymer may have a polar substituent of the polymer and a crosslinkable group introduced by salt formation with a substituent having a countercharge with the polar substituent and a compound having an ethylenically unsaturated bond. A monomer other than the above, preferably a hydrophilic monomer may be further copolymerized.

Specifically, a silane coupling agent having an addition-polymerizable ethylenic double bond reactive group described in JP-A No. 10-282679, and an ethylenic substance described in JP-A-2-304441. A phosphorus compound having a double bond reactive group is preferably mentioned. Crosslinkable groups (preferably ethylenically unsaturated bonding groups) and supports described in JP-A-2005-238816, JP-A-2005-125479, JP-A-2006-239867, and JP-A-2006-215263. Low molecular weight or high molecular weight compounds having functional and hydrophilic groups that interact with the surface are also preferably used.
More preferable examples thereof include polymer polymers having an adsorptive group, a hydrophilic group and a crosslinkable group that can be adsorbed on the surface of the support described in JP-A-2005-125479 and JP-A-2006-188038.

The content of the ethylenically unsaturated bond group in the polymer used for the undercoat layer is preferably 0.1 mmol to 10.0 mmol, more preferably 0.2 mmol to 5.5 mmol per 1 g of the polymer.
The weight average molecular weight (Mw) of the polymer used for the undercoat layer is preferably 5,000 or more, more preferably 10,000 to 300,000.

[Hydrophilic compound]
The undercoat layer preferably contains a hydrophilic compound from the viewpoint of developability.
The hydrophilic compound is not particularly limited, and a known hydrophilic compound used for the undercoat layer can be used.
Preferred examples of the hydrophilic compound include phosphonic acids having an amino group such as carboxymethyl cellulose and dextrin, organic phosphonic acids, organic phosphoric acids, organic phosphinic acids, amino acids, and hydrochlorides of amines having a hydroxy group.
Further, as the hydrophilic compound, a compound having an amino group or a functional group having a polymerization prohibition ability and a group interacting with the surface of the support (for example, 1,4-diazabicyclo [2.2.2] octane (DABCO)). , 2,3,5,6-tetrahydroxy-p-quinone, chloranyl, sulfophthalic acid, ethylenediaminediacetic acid (EDTA) or a salt thereof, hydroxyethylethylenediaminediacetic acid or a salt thereof, dihydroxyethylethylenediaminediacetic acid or a salt thereof, hydroxy Ethylenediaminediacetic acid or a salt thereof, etc.) are preferably mentioned.

The hydrophilic compound preferably contains a hydroxycarboxylic acid or a salt thereof from the viewpoint of suppressing scratches and stains.
Further, the hydrophilic compound, preferably a hydroxycarboxylic acid or a salt thereof, is preferably contained in the layer on the aluminum support from the viewpoint of suppressing scratches and stains. Further, the layer on the aluminum support is preferably a layer on the side where the image recording layer is formed, and is preferably a layer in contact with the aluminum support.
As the layer on the aluminum support, an undercoat layer or an image recording layer is preferably mentioned as a layer in contact with the aluminum support. Further, a layer other than the layer in contact with the aluminum support, for example, the outermost layer or the image recording layer may contain a hydrophilic compound, preferably a hydroxycarboxylic acid or a salt thereof.
In the lithographic printing plate original plate according to the present disclosure, it is preferable that the image recording layer contains a hydroxycarboxylic acid or a salt thereof from the viewpoint of suppressing scratches and stains.
Further, in the lithographic printing plate original plate according to the present disclosure, an embodiment in which the surface of the aluminum support on the image recording layer side is surface-treated with a composition containing at least hydroxycarboxylic acid or a salt thereof (for example, an aqueous solution) is also preferably mentioned. Be done. In the above embodiment, the treated hydroxycarboxylic acid or a salt thereof is detected at least in a state of being contained in a layer on the image recording layer side (for example, an image recording layer or an undercoat layer) in contact with an aluminum support. be able to.
By containing hydroxycarboxylic acid or a salt thereof in the layer on the image recording layer side in contact with the aluminum support such as the undercoat layer, the surface of the aluminum support on the image recording layer side can be made hydrophilic, and the aluminum support can also be made hydrophilic. The contact angle with water on the surface of the image recording layer side by the aerial water droplet method can be easily set to 110 ° or less, and the scratch and stain suppression property is excellent.

Hydroxycarboxylic acid is a general term for organic compounds having one or more carboxy groups and one or more hydroxy groups in one molecule, and is also called hydroxy acid, oxy acid, oxycarboxylic acid, or alcoholic acid (). Iwanami Physics and Chemistry Dictionary 5th Edition, published by Iwanami Shoten Co., Ltd. (1998)).
The hydroxycarboxylic acid or a salt thereof is preferably represented by the following formula (HC).
Formula (HC): R ^HC (OH) _mhc ( _COM ^HC ) nhc
In formula (HC), R ^HC represents a mhc + nhc valent organic group, M ^HC independently represents a hydrogen atom, an alkali metal, or onium, and mhc and nhc each independently represent an integer of 1 or more. Represented, when n is 2 or more, M may be the same or different.

In the formula ^(HC), as the organic group for mhc + NHC value represented by ^{R HC,} it includes mhc + NHC valent hydrocarbon group. The hydrocarbon group may have a substituent and / or a linking group.
Examples of the hydrocarbon group include a group having a mhc + nhc valence derived from an aliphatic hydrocarbon, for example, an alkylene group, an alkanthryl group, an alkanetetrayl group, an alcantyl group, an alkenylene group, an alkanthryl group and an alkentetrayl group. Groups of mhc + nhc valence derived from aromatic hydrocarbons such as groups, alkenylpentyl groups, alkynylene groups, alkyntriyl groups, alkynetetrayl groups, alkynpentyl groups, etc., such as allylene groups, allenetriyl groups, allenes. Examples thereof include a tetrayl group and an arenepentile group. Examples of the substituent include an alkyl group, an alkenyl group, an alkynyl group, an aralkyl group, an aryl group and the like. Specific examples of the substituent include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group and a hexadecyl group. Octadecyl group, eicosyl group, isopropyl group, isobutyl group, s-butyl group, t-butyl group, isopentyl group, neopentyl group, 1-methylbutyl group, isohexyl group, 2-ethylhexyl group, 2-methylhexyl group, cyclohexyl group, Cyclopentyl group, 2-norbornyl group, methoxymethyl group, methoxyethoxyethyl group, allyloxymethyl group, phenoxymethyl group, acetyloxymethyl group, benzoyloxymethyl group, benzyl group, phenethyl group, α-methylbenzyl group, 1- Methyl-1-phenylethyl group, p-methylbenzyl group, cinnamyl group, allyl group, 1-propenylmethyl group, 2-butenyl group, 2-methylallyl group, 2-methylpropenylmethyl group, 2-propynyl group, 2- Butynyl group, 3-butynyl group, phenyl group, biphenyl group, naphthyl group, trill group, xylyl group, mesityl group, cumenyl group, methoxyphenyl group, ethoxyphenyl group, phenoxyphenyl group, acetoxyphenyl group, benzoyloxyphenyl group , Methoxycarbonylphenyl group, ethoxycarbonylphenyl group, phenoxycarbonylphenyl group and the like. The linking group is composed of at least one atom selected from the group consisting of a hydrogen atom, a carbon atom, an oxygen atom, a nitrogen atom, a sulfur atom and a halogen atom, and the number of atoms thereof is preferably 1 to 50. Is. Specific examples thereof include an alkylene group, a substituted alkylene group, an arylene group, a substituted arylene group and the like, and a plurality of these divalent groups are linked by any of an amide bond, an ether bond, a urethane bond, a urea bond and an ester bond. It may have a structure that has been modified.

^Examples of the alkali metal represented by MHC include lithium, sodium, potassium and the like, and sodium is particularly preferable. Examples of onium include ammonium, phosphonium, sulfonium and the like, and ammonium is particularly preferable.
Further, M ^HC, from the viewpoint of scratch stain inhibitory, preferably an alkali metal or an onium, and more preferably an alkali metal.
The total number of mhc and nhc is preferably 3 or more, more preferably 3 to 8, and even more preferably 4 to 6.

The hydroxycarboxylic acid or a salt thereof preferably has a molecular weight of 600 or less, more preferably 500 or less, and particularly preferably 300 or less. Moreover, the molecular weight is preferably 76 or more.
Specifically, the hydroxycarboxylic acid constituting the hydroxycarboxylic acid or the salt of the hydroxycarboxylic acid is gluconic acid, glycolic acid, lactic acid, tartron acid, hydroxybutyric acid (2-hydroxybutyric acid, 3-hydroxybutyric acid, γ-Hydroxybutyric acid, etc.), malic acid, tartaric acid, citramalic acid, citric acid, isocitrate, leucic acid, mevalonic acid, pantoic acid, lysynolic acid, lysine lysic acid, cerebronic acid, quinic acid, shikimic acid, monohydroxybenzoic acid derivative (Salicylic acid, cleosortic acid (homosalicylic acid, hydroxy (methyl) benzoic acid), vanillic acid, syring acid, etc.), dihydroxybenzoic acid derivatives (pyrocatechuic acid, resorcylic acid, protocatechuic acid, gentidic acid, orceric acid, etc.), trihydroxy Benzoic acid derivatives (such as galvanic acid), phenylacetic acid derivatives (mandelic acid, benzylic acid, atrolactinic acid, etc.), hydrosilicic acid derivatives (merilotoic acid, floret acid, bear acid, umbel acid, coffee acid, ferulic acid, cinnapic acid, etc.) Celebronic acid, carmic acid, etc.) and the like.

Among these, as the hydroxycarboxylic acid or the hydroxycarboxylic acid constituting the salt of the hydroxycarboxylic acid, a compound having two or more hydroxy groups is preferable from the viewpoint of suppressing scratches and stains, and the hydroxy group is preferable. A compound having 3 or more hydroxy groups is more preferable, a compound having 5 or more hydroxy groups is further preferable, and a compound having 5 to 8 hydroxy groups is particularly preferable.
Further, as a substance having one carboxy group and two or more hydroxy groups, gluconic acid or shikimic acid is preferable.
Citric acid or malic acid is preferable as having two or more carboxy groups and one hydroxy group.
Tartaric acid is preferable as having two or more carboxy groups and hydroxy groups, respectively.
Among them, gluconic acid is particularly preferable as the hydroxycarboxylic acid.

The hydrophilic compound may be used alone or in combination of two or more.

When the undercoat layer contains a hydrophilic compound (preferably hydroxycarboxylic acid or a salt thereof), the content of the hydrophilic compound (preferably hydroxycarboxylic acid and a salt thereof) is 0.01 mass by mass with respect to the total mass of the undercoat layer. It is preferably% to 50% by mass, more preferably 0.1% by mass to 40% by mass, and particularly preferably 1.0% by mass to 30% by mass.

In addition to the above-mentioned compound for the undercoat layer, the undercoat layer is a chelating agent to prevent stains over time.
It may contain a secondary or tertiary amine, a polymerization inhibitor and the like.

The undercoat layer can be formed by dissolving each of the above-mentioned necessary components in a known solvent to prepare a coating liquid, applying the coating liquid on the support by a known method, and drying.
The coating amount (solid content) of the undercoat layer is ^preferably from ^{0.1mg / m 2 ~300mg / m 2} , 5mg / m 2 ~200mg / m 2 is more preferable.

The lithographic printing plate original plate according to the present disclosure may have other layers other than those described above.
The other layer is not particularly limited and may have a known layer. For example, a back coat layer may be provided on the side of the support opposite to the image recording layer side, if necessary.

≪Manufacturing method of lithographic printing plate and lithographic printing method≫
A lithographic printing plate can be produced by exposing the original plate of the lithographic printing plate according to the present disclosure to an image and performing a developing process.
The method for producing a lithographic printing plate according to the present disclosure includes a step of exposing the lithographic printing plate original plate according to the present disclosure to an image (hereinafter, also referred to as an “exposure step”), and printing ink and wetting on a printing machine. It is preferable to include a step of supplying at least one selected from the group consisting of water to remove the image recording layer of the non-image portion (hereinafter, also referred to as “on-machine development step”).
In the flat plate printing method according to the present disclosure, printing is performed by supplying at least one selected from the group consisting of a step of exposing the flat plate printing plate original plate according to the present disclosure to an image (exposure step) and a group consisting of printing ink and dampening water. A step of producing a flat plate printing plate by removing the image recording layer of the non-image portion on the machine (machine development step), and a step of printing with the obtained flat plate printing plate (hereinafter, also referred to as "printing process"). It is preferable to include.

Hereinafter, preferred embodiments of each step will be sequentially described with respect to the method for producing a lithographic printing plate according to the present disclosure and the lithographic printing method according to the present disclosure. The lithographic printing plate original plate according to the present disclosure can also be developed with a developing solution.
Hereinafter, the exposure step and the on-machine development step in the lithographic printing plate manufacturing method will be described, but the exposure step in the lithographic printing plate manufacturing method according to the present disclosure and the exposure step in the lithographic printing method according to the present disclosure are the same. It is a step, and the on-machine development step in the method for producing a lithographic printing plate according to the present disclosure and the on-machine development step in the lithographic printing method according to the present disclosure are the same steps.

<Exposure process>
The method for producing a lithographic printing plate according to the present disclosure preferably includes an exposure step of exposing the lithographic printing plate original plate according to the present disclosure to an image to form an exposed portion and an unexposed portion. It is preferable that the lithographic printing plate original plate according to the present disclosure is exposed to an image by laser exposure through a transparent original image having a line image, a halftone dot image, or the like, or by laser light scanning with digital data.
The wavelength of the light source is preferably 750 nm to 1,400 nm. As a light source having a wavelength of 750 nm to 1,400 nm, a solid-state laser or a semiconductor laser that emits infrared rays is suitable. For the infrared laser, the output is preferably more than 100 mW, preferably, the exposure time per pixel is preferably within 20 microseconds, also that the amount of irradiation energy is 10mJ ^/ cm ² ~300mJ ^/ cm 2 preferable. Further, it is preferable to use a multi-beam laser device in order to shorten the exposure time. The exposure mechanism may be any of an inner drum method, an outer drum method, a flatbed method and the like.
Image exposure can be performed by a conventional method using a platesetter or the like. In the case of on-machine development, the lithographic printing plate original plate may be mounted on the printing machine and then the image may be exposed on the printing machine.

<In-machine development process>
The method for producing a lithographic printing plate according to the present disclosure is an on-machine development step of supplying at least one selected from the group consisting of printing ink and dampening water on a printing machine to remove an image recording layer in a non-image area. It is preferable to include it.
The on-machine development method will be described below.

[In-machine development method]
In the on-machine development method, the image-exposed lithographic printing plate original plate supplies oil-based ink and water-based components on the printing machine, and the image recording layer in the non-image area is removed to produce a lithographic printing plate. Is preferable.
That is, either the flat plate printing plate original plate is mounted on the printing machine as it is without any development processing after the image exposure, or the flat plate printing plate original plate is mounted on the printing machine and then the image is exposed on the printing machine, and then When printing is performed by supplying an oil-based ink and a water-based component, in the non-image area, an uncured image recording layer is formed by one or both of the supplied oil-based ink and the water-based component in the initial stage of printing. It dissolves or disperses and is removed, exposing a hydrophilic surface to that portion. On the other hand, in the exposed portion, the image recording layer cured by exposure forms an oil-based ink receiving portion having a lipophilic surface. The first supply to the plate surface may be an oil-based ink or a water-based component, but the oil-based ink is first supplied in terms of preventing contamination by the components of the image recording layer from which the water-based components have been removed. Is preferable. In this way, the lithographic printing plate original plate is developed on the printing machine and used as it is for printing a large number of sheets. As the oil-based ink and the water-based component, ordinary printing ink for lithographic printing and dampening water are preferably used.

As the laser for image-exposing the lithographic printing plate original plate according to the present disclosure, the wavelength of the light source is preferably 300 nm to 450 nm or 750 nm to 1,400 nm. In the case of a light source of 300 nm to 450 nm, a lithographic printing plate original plate containing a sensitizing dye having an absorption maximum in this wavelength region in the image recording layer is preferably used, and a light source of 750 nm to 1,400 nm is preferably used as described above. Be done. As a light source of 300 nm to 450 nm, a semiconductor laser is suitable.

<Printing process>
The lithographic printing method according to the present disclosure includes a printing step of supplying printing ink to a lithographic printing plate to print a recording medium.
The printing ink is not particularly limited, and various known inks can be used as desired. Moreover, as a printing ink, an oil-based ink or an ultraviolet curable ink (UV ink) is preferably mentioned.
Further, in the printing process, dampening water may be supplied as needed.
Further, the printing process may be continuously performed in the on-machine development process without stopping the printing machine.
The recording medium is not particularly limited, and a known recording medium can be used if desired.

In the method for producing a lithographic printing plate from the lithographic printing plate original plate according to the present disclosure and the lithographic printing method according to the present disclosure, lithographic printing is performed before, during, and between exposure and development as necessary. The entire surface of the plate may be heated. By such heating, the image formation reaction in the image recording layer is promoted, and advantages such as improvement of sensitivity and printing durability and stabilization of sensitivity may occur. The heating before development is preferably performed under mild conditions of 150 ° C. or lower. With the above aspect, it is possible to prevent problems such as hardening of the non-image portion. It is preferable to use very strong conditions for heating after development, preferably in the range of 100 ° C to 500 ° C. Within the above range, a sufficient image enhancement effect can be obtained, and problems such as deterioration of the support and thermal decomposition of the image portion can be suppressed.

Hereinafter, the present disclosure will be described in detail by way of examples, but the present disclosure is not limited thereto. In this embodiment, "%" and "part" mean "% by mass" and "part by mass", respectively, unless otherwise specified. In the polymer compound, the molecular weight is the weight average molecular weight (Mw), and the ratio of the constituent repeating units is the molar percentage, except for those specified specifically. The weight average molecular weight (Mw) is a value measured as a polystyrene-equivalent value by a gel permeation chromatography (GPC) method.

[Examples 1 to 22 and Comparative Examples 1 to 3]
<Preparation of support>
(A) Alkaline etching treatment An aqueous caustic soda solution having a caustic soda concentration of 26% by mass and an aluminum ion concentration of 6.5% by mass was sprayed onto an aluminum plate at a temperature of 70 ° C. to perform an etching treatment. Then, it was washed with water by spraying. The amount of aluminum dissolved on the surface to be subjected to the electrochemical roughening treatment later was 5 g / m ² .

(B) Desmat treatment using an acidic aqueous solution (first desmat treatment)
Next, a desmat treatment was performed using an acidic aqueous solution. As the acidic aqueous solution used for the desmat treatment, an aqueous solution of sulfuric acid 150 g / L was used. The liquid temperature was 30 ° C. An acidic aqueous solution was sprayed onto an aluminum plate to perform desmat treatment for 3 seconds. Then, it was washed with water.

(C) Electrochemical roughening treatment Next, an electrolytic solution having a hydrochloric acid concentration of 14 g / L, an aluminum ion concentration of 13 g / L, and a sulfuric acid concentration of 3 g / L is used, and electrochemical roughening is performed using an AC current. Processing was performed. The liquid temperature of the electrolytic solution was 30 ° C. The aluminum ion concentration was adjusted by adding aluminum chloride.
The AC current waveform is a sinusoidal wave with symmetrical positive and negative waveforms, the frequency is 50 Hz, the anode reaction time and cathode reaction time in one AC current cycle are 1: 1, and the current density is the peak current value of the AC current waveform. It was 75 A / dm ^2. The electric amount was 450C / dm ² in terms of the total electric quantity aluminum plate participating in the anode reaction, electrolytic treatment was carried out four times to open the energization interval 112.5C / dm ² by 4 seconds. A carbon electrode was used as the counter electrode of the aluminum plate. Then, it was washed with water.

(D) Alkaline etching treatment An etching treatment is performed by spraying an aqueous solution of Kasei soda having a Kasei soda concentration of 5% by mass and an aluminum ion concentration of 0.5% by mass on an electrochemically roughened aluminum plate at a temperature of 45 ° C. rice field. The dissolved amount of aluminum on the surface subjected to the electrochemical roughening treatment was 0.2 g / m ² . Then, it was washed with water.

(E) Desmat treatment using an acidic aqueous solution Next, a desmat treatment was performed using an acidic aqueous solution. Specifically, an acidic aqueous solution was sprayed onto an aluminum plate to perform a desmat treatment for 3 seconds. As the acidic aqueous solution used for the desmat treatment, an aqueous solution having a sulfuric acid concentration of 170 g / L and an aluminum ion concentration of 5 g / L was used. The liquid temperature was 30 ° C.

(F) First-stage anodizing treatment The first-stage anodizing treatment (also referred to as first anodic oxidation treatment) was performed using the anodic oxidation treatment apparatus 610 by direct current electrolysis having the structure shown in FIG. Specifically, the first anodizing treatment was performed under the conditions of the "first anodizing treatment" column shown in Table 1 below to form an anodized film having a predetermined film amount.
Hereinafter, the anodizing treatment apparatus 610 shown in FIG. 3 will be described.
In the anodizing apparatus 610 shown in FIG. 3, the aluminum plate 616 is conveyed as shown by an arrow in FIG. The aluminum plate 616 is charged to (+) by the feeding electrode 620 in the feeding tank 612 in which the electrolytic solution 618 is stored. Then, the aluminum plate 616 is conveyed upward by the roller 622 in the power supply tank 612, turned downward by the nip roller 624, and then conveyed toward the electrolytic treatment tank 614 in which the electrolytic solution 626 is stored, and is conveyed by the roller 628. Turns horizontally. Next, the aluminum plate 616 is charged to (−) by the electrolytic electrode 630 to form an anodic oxide film on the surface thereof, and the aluminum plate 616 leaving the electrolytic treatment tank 614 is conveyed to a subsequent step. In the anodizing apparatus 610, the roller 622, the nip roller 624, and the roller 628 constitute a turning means, and the aluminum plate 616 is formed in the inter-tank portion between the feeding tank 612 and the electrolytic treatment tank 614, and the rollers 622, 624, and 628 are described. Is transported in a chevron shape and an inverted U shape. The feeding electrode 620 and the electrolytic electrode 630 are connected to a DC power supply 634.

(G) Pore-wide treatment The aluminum plate that has been anodized is immersed in a Kasei-soda aqueous solution having a temperature of 40 ° C., a Kasei-soda concentration of 5% by mass, and an aluminum ion concentration of 0.5% by mass under the conditions shown in Table 1 below to perform a pore-wide treatment. rice field. Then, it was washed with water by spraying.

(H) Second Anodizing Treatment A second-stage anodizing treatment (also referred to as a second anodizing treatment) was performed using an anodizing treatment apparatus 610 by direct current electrolysis having the structure shown in FIG. Specifically, the second anodizing treatment was performed under the conditions of the "second anodizing treatment" column shown in Table 1 below to form an anodized film having a predetermined film amount.

The support was manufactured as described above.
^{The L *} a ^* b ^* lightness L ^{* of} the surface of the anodic oxide film of the micropores of the obtained support, the average diameter and depth of the large-diameter pores in the micropores on the surface of the oxide film, and the micropores. Average diameter (nm) and depth at the communication position of the small diameter hole, depth (nm) of the large diameter hole and the small diameter hole, micropore density, and anodic oxidation from the bottom of the small diameter hole to the surface of the aluminum plate. The thickness of the film (also referred to as the film thickness) is summarized in Table 2.
In Table 1, the film amount (AD) in the first anodizing treatment column and the film amount (AD) in the second anodizing treatment column represent the film amount obtained by each treatment. The electrolytic solution used is an aqueous solution containing the components in Table 1.

<Formation of undercoat layer>
An undercoat layer coating solution having the following composition was applied onto the obtained support so that the dry coating amount was 0.1 g / m ² to form an undercoat layer.

[Coating liquid for undercoat layer]
-Compound for undercoat layer (U-1, 11% aqueous solution below): 0.10502 parts-Sodium gluconate: 0.0700 parts-Surfactant (Emarex (registered trademark) 710, Nippon Emulsion Co., Ltd.): 0 .00159 parts ・ Preservative (Biohope L, KAI Kasei Co., Ltd.): 0.00149 parts ・ Water: 3.29000 parts

<Formation of image recording layer>
An image recording layer coating liquid containing each component shown in Table 3 below on the undercoat layer (however, the image recording layer coating liquid contains each component shown in Table 3 and contains 1-methoxy-2-propanol (1-methoxy-2-propanol). MFG): Methyl ethyl ketone (MEK): Methanol = 4: 4: 1 (mass ratio) prepared to have a solid content of 6% by mass) was coated in a bar and dried in an oven at 120 ° C. for 40 seconds. An image recording layer having a dry coating amount of 1.0 g / m ^{2 was formed.}
The image recording layer coating liquid containing the polymer particles (microgels) was prepared by mixing and stirring a photosensitive liquid containing components other than the following microgel liquid and the following microgel liquid immediately before coating.

The details of each component used in Table 3 are as follows.

[Infrared absorber]
IR-1: Degradable infrared absorber, compound having the following structure, HOMO = -5.43eV, LUMO = -3.95eV.
IR-2: Non-decomposable infrared absorber, compound having the following structure, HOMO = -5.35eV, LUMO = -3.73eV.

[Electron-accepting polymerization initiator]
IA-1: Compound with the following structure, LUMO = -3.21eV
IA-2: Onium compound, compound having the following structure, LUMO = -3.02eV

[Electron-donated polymerization initiator]
TPB: Borate compound, sodium tetraphenylborate, HOMO = -5.90eV)

[Polymerizable compound A]
-A-1: Urethane (meth) acrylate oligomer, U-10HA (number of functional groups: 10), Shin Nakamura Chemical Industry Co., Ltd.
A-2: Urethane (meth) acrylate oligomer, UA-510H (number of functional groups: 10), Kyoeisha Chemical Co., Ltd.
A-3: Urethane (meth) acrylate oligomer, KRM8452 (number of functional groups: 10), Daicel Ornex Co., Ltd.
A-4: Urethane (meth) acrylate oligomer, U-15HA (number of functional groups: 15), Shin Nakamura Chemical Industry Co., Ltd.
A-5: Urethane (meth) acrylate oligomer, CN8885NS (number of functional groups: 9), Sartmer A-6: Urethane (meth) acrylate oligomer, CN9013NS (number of functional groups: 9), Sartmer A-7: Epoxy (Meta) acrylate oligomer, NK oligo EA-7420 / PGMAc (number of functional groups: 10 to 15), Shin Nakamura Chemical Industry Co., Ltd.
-A-8: Epoxy (meth) acrylate oligomer, CN153, Sartmer Co., Ltd.-A-9: Polyester (meth) acrylate oligomer, CN2267, Sartmer Co., Ltd.

[Polymerizable compound B]
B-1: Bifunctional Methacrylate, AZ Electronics FST 510 (a reaction product of 1 mol of 2,2,4-trimethylhexamethylene diisocyanate and 2 mol of hydroxyethyl methacrylate, which is a compound having the following structure, methyl ethyl ketone 82. Mass% solution)
B-2: Ethoxylated bisphenol A dimethacrylate, compound having the following structure, BPE-80N from Shin Nakamura Chemical Industry Co., Ltd.
B-3: Ethoxylated bisphenol A diacrylate, compound having the following structure (m + n = 10), A-BPE-10 of Shin Nakamura Chemical Industry Co., Ltd.

[Binder polymer]
BP-1: Polyvinyl butyral having the following structure, Sekisui Chemical Co., Ltd. Eslek BX-5 (Z), l is 72 mol%, m is 1 mol%, n is 27 mol%, and the weight average molecular weight is 130,000. be

[Surfactant]
Anionic surfactant: A compound having the following structure

Fluorosurfactant: A compound having the following structure (weight average molecular weight: 13,000)

[Microgel liquid]
-Microgel (polymer particles): 2.640 parts-Distilled water: 2.425 parts The method for preparing the microgel used in the above microgel solution is shown below.

-Preparation of multivalent isocyanate compound-
Bismastris (2-ethyl) in a suspension solution of ethyl acetate (25.31 parts) containing 17.78 parts (80 mol equivalents) of isophorone diisocyanate and 7.35 parts (20 mol equivalents) of the following polyvalent phenol compound (1). Hexanoate) (Neostan U-600, manufactured by Nitto Kasei Co., Ltd.) 0.043 part was added and stirred. When the exotherm subsided, the reaction temperature was set to 50 ° C. and the mixture was stirred for 3 hours to obtain an ethyl acetate solution (50% by mass) of the polyhydric isocyanate compound (1).

-Preparation of microgel-
The following oil phase components and aqueous phase components were mixed and emulsified at 12,000 rpm for 10 minutes using a homogenizer. After stirring the obtained emulsion at 45 ° C. for 4 hours, 10 mass of 1,8-diazabicyclo [5.4.0] undec-7-en-octylate (U-CAT SA102, manufactured by San-Apro Co., Ltd.) 5.20 g of a% aqueous solution was added, the mixture was stirred at room temperature for 30 minutes, and allowed to stand at 45 ° C. for 24 hours. The solid content concentration was adjusted to 20% by mass with distilled water to obtain an aqueous dispersion of microgel (1). When the average particle size was measured by the light scattering method, it was 0.28 μm.

~ Oil phase component ~
(Component 1) Ethyl acetate: 12.0 parts (Component 2) Trimethylolpropane (6 eq) and xylene diisocyanate (18 eq) are added, to which one-terminal methylated polyoxyethylene (1 eq, oxy) is added. Additive (50 mass% ethyl acetate solution, manufactured by Mitsui Kagaku Co., Ltd.) to which an ethylene unit repetition number: 90) was added: 3.76 parts (component 3) polyhydric isocyanate compound (1) (50 mass% acetate) As an ethyl solution): 15.0 parts (component 4) 65% by mass ethyl acetate solution of dipentaerythritol pentaacrylate (SR-399, manufactured by Sartmer) 11.54 parts (component 5) sulfonate type surfactant (Pionin A-41-C, manufactured by Takemoto Oil & Fat Co., Ltd.) 10% ethyl acetate solution: 4.42 parts

~ Aqueous phase component ~
Distilled water: 46.87 parts

<Formation of outermost layer>
In Examples 2 to 21 and Comparative Examples 1 to 3, the outermost layer coating liquid shown in Table 4 below (however, the outermost layer coating liquid contains each component shown in Table 4 and ion exchanges) on the image recording layer. (Prepared to have a solid content of 20% by mass with water) was bar-coated and dried in an oven at 120 ° C. for 60 seconds to form an outermost layer having ^{a dry coating amount of 0.41 g / m 2.}
Through the above steps, a lithographic printing plate original plate was obtained.

The details of each component used in Table 4 are as follows.

[Infrared absorber]
-IR-3: Compounds with the following structure, decomposition compounds (discolorable compounds)
-IR-4: A compound having the following structure

[Water-soluble polymer]
-Water-soluble polymer: Polyvinyl alcohol, Sigma-Aldrich's Mowiol 4-88

[Hydrophobic polymer]
Hydrophobic polymer: polyvinylidene chloride aqueous dispersion, Biofan® A50 manufactured by Solvin

-Surfactant: Nonionic surfactant, BASF Lutensol (registered trademark) A8

<Evaluation of lithographic printing plate original plate>
(1) Changes in on-machine developability over time The lithographic printing plate original plate produced as described above was subjected to a Magnus800 Quantum manufactured by Kodak equipped with an infrared semiconductor laser, with an output of 27 W, an outer drum rotation speed of 450 rpm, and a resolution of 2,400 dpi. Exposure (corresponding to irradiation energy of 110 mJ / cm ^{2) under the conditions of.} The exposed image includes a solid image and a chart of 50% halftone dots on the AM screen (Amplitude Modulation Screen).
The obtained exposed original plate was attached to the cylinder of a chrysanthemum-sized Heidelberg printing machine SX-74 without developing. A non-woven fabric filter and a dampening water circulation tank having a capacity of 100 L having a built-in temperature control device were connected to the printing machine. Damping water S-Z1 (manufactured by Fujifilm Co., Ltd.) 2.0% dampening water 80L is charged in the circulation device, and T & K UV OFS K-HS ink GE-M (manufactured by T & K TOKA Co., Ltd.) is used as printing ink. ) Is used to supply dampening water and ink using the standard automatic printing start method, and then printed on Tokishi Art Paper (ream amount: 76.5 kg, manufactured by Mitsubishi Paper Mills Limited) at a printing speed of 10,000 sheets per hour. 200 sheets were printed.
In the above-mentioned on-machine development, the number of printing papers required until the ink was not transferred to the non-image portion (hereinafter, also referred to as the number of on-machine developments) was determined. It can be said that the smaller the number of sheets developed on the machine, the better the developability on the machine.
As a result, in both the planographic printing plate original plate of the example and the comparative example, the number of sheets developed on the machine was 100 or less.

The above-mentioned measurement of the number of on-machine developments was carried out in 2 days, and the lithographic printing plate original plate (hereinafter, also referred to as the initial lithographic printing plate original plate) within 3 days at room temperature after the plate was formed. The initial lithographic printing plate original plate was stored at 50 ° C. and 70% RH for 3 days, and then the lithographic printing plate original plate (also referred to as the lithographic printing plate original plate after aging) was used.
When the number of on-machine developed sheets in the initial lithographic printing plate original plate is D (Fr) and the number of on-machine developed sheets in the lithographic printing plate original plate after aging is D (Th), the change ΔD with time of the on-machine developability is as follows. Is sought after.
ΔD = D (Th) / D (Fr)
It can be said that the closer the value of ΔD is to 1, the better the on-machine developability over time. The evaluation results are shown in Table 5.
-Evaluation criteria-
5: 1.00 ≤ ΔD ≤ 1.25
4: 1.25 <ΔD ≦ 1.50
3: 1.50 <ΔD ≦ 1.75
2: 1.75 <ΔD ≦ 2.00
1: 2.00 <ΔD

(2) Evaluation of printing resistance (UV printing resistance) The lithographic printing plate original plate produced as described above was subjected to a Magnus 800 Quantum manufactured by Kodak equipped with an infrared semiconductor laser, and had an output of 27 W, an outer drum rotation speed of 450 rpm, and a resolution. Exposure was performed under the condition of 2,400 dpi (corresponding to ^{irradiation energy of 110 mJ / cm 2).} The exposed image includes a solid image and a chart of 10% halftone dots on the AM screen.
The obtained exposed original plate was attached to the cylinder of a chrysanthemum-sized Heidelberg printing machine SX-74 without developing. A non-woven fabric filter and a dampening water circulation tank having a capacity of 100 L having a built-in temperature control device were connected to the printing machine. Damping water S-Z1 (manufactured by Fujifilm Co., Ltd.) 2.0% dampening water 80L is charged in the circulation device, and T & K UV OFS K-HS ink GE-M (manufactured by T & K TOKA Co., Ltd.) is used as printing ink. ) Is used to supply dampening water and ink using the standard automatic printing start method, and then printed on Tokubishi Art (ream amount: 76.5 kg, manufactured by Mitsubishi Paper Mills Limited) at a printing speed of 10,000 sheets per hour. 500 sheets were printed.
Then, further printing was performed. As the number of printed sheets was increased, the image portion was gradually worn, and the ink density on the printed matter decreased. The number of printed copies is taken as the number of printed copies when the value measured by the Gretag densitometer (manufactured by Gretag Macbeth) for the halftone dot area ratio of the AM screen 10% halftone dot in the printed matter is 3% lower than the measured value of the 500th printed matter. The printing durability was evaluated.
The evaluation was made according to the following criteria based on the relative printing durability of 100 when the number of printed sheets was 50,000. The larger the value, the better the printing durability. The evaluation results are shown in Table 5.
Relative printing resistance = (number of prints of target lithographic printing plate original plate) / 50,000 x 100
-Evaluation criteria-
4: Relative print resistance value exceeds 90 3: Relative print resistance value is more than 80 and 90 or less 2: Relative print resistance value is more than 60 and 80 or less 1: Relative print resistance The value of is 60 or less

(3) Evaluation of UV plate jump suppression property The lithographic printing plate original plate produced as described above was subjected to a Magnus 800 Quantum manufactured by Kodak equipped with an infrared semiconductor laser, and had an output of 27 W, an outer surface drum rotation speed of 450 rpm, and a resolution of 2,400 dpi. Exposure was performed under the conditions (equivalent to ^{irradiation energy of 110 mJ / cm 2).} The exposed image includes a solid image and a chart of 3% halftone dots on the AM screen.
A piano wire with a diameter of 0.4 mm (ESCO Co., Ltd.) is attached to the halftone dots of the obtained exposed original plate in the direction perpendicular to the rotation direction of the plate cylinder, and is a chrysanthemum-sized Heidelberg without development processing. It was attached to the cylinder of the printing machine SX-74 manufactured by the company. A non-woven fabric filter and a dampening water circulation tank having a capacity of 100 L having a built-in temperature control device were connected to the printing machine. Damping water S-Z1 (manufactured by Fujifilm Co., Ltd.) 2.0% dampening water 80L is charged in the circulation device, and T & K UV OFS K-HS ink GE-M (manufactured by T & K TOKA Co., Ltd.) is used as printing ink. ) Is used to supply dampening water and ink using the standard automatic printing start method, and then printed on Tokubishi Art (Mitsubishi Paper Mills Limited, ream weight: 76.5 kg) at a printing speed of 10,000 sheets per hour. I printed it.
When the number of printed sheets reached 2,000, the piano wire was removed from the plate, set in the printing machine again, and printing was started. After resuming, the 100th printed matter was confirmed, the image part corresponding to the position of the piano wire was confirmed, and whether or not the inking defect occurred was visually confirmed using a 50x magnifying glass. Similarly, confirmation was performed every 2,000 sheets, and the evaluation was completed when poor inking occurred.
It can be said that the larger the number of printed sheets until poor inking occurs, the better the "UV plate skipping inhibitory property". The results are shown in Table 5.
-Evaluation criteria-
4: The number of printed sheets until poor inking occurs is 20,000 or more.
3: The number of printed sheets until poor inking occurs is 10,000 or more and less than 20,000.
2: The number of printed sheets until poor inking occurs is 5,000 or more and less than 10,000.
1: The number of printed sheets until poor inking occurs is less than 5,000.

(4) Evaluation of Visibility The obtained lithographic printing plate original plate was exposed by Creo's Trendsetter 3244VX equipped with a water-cooled 40W infrared semiconductor laser under the conditions of output 11.5W, outer surface drum rotation speed 220rpm, and resolution 2,400dpi. .. The exposure was performed in an environment of 25 ° C. and 50% RH.
The lithographic printing plate original plate immediately after exposure (also called the initial lithographic printing plate original plate) and the lithographic printing plate original plate after exposure are stored at 25 ° C. and 70% RH for 3 days, and then the lithographic printing plate original plate (after aging). The color development was measured for each of the lithographic printing plate and the original plate). The measurement was performed by the SCE (specular reflection light removal) method using a spectrophotometer CM2600d manufactured by Konica Minolta Co., Ltd. and an operation software CM-S100W. Visibility (visibility) ^uses the L ^* a * ^{b *} color system of ^{L *} value (lightness) was evaluated by the difference ΔL between the ^{L *} values of the ^{L *} value and the unexposed portions of the exposed portion. It can be said that the larger the value of ΔL, the better the visibility. The results are shown in Table 5.
-Evaluation criteria-
3: ΔL is 4 or more 2: ΔL is 2 or more and less than 4 1: ΔL is less than 2

As is clear from Table 5, the lithographic printing plate original plate according to the examples is less likely to deteriorate in on-machine developability over time than the lithographic printing plate original plate according to the comparative example, and the lithographic printing plate printing is also excellent in printing durability. You can see that the edition is available.
Further, it can be seen that, as the lithographic printing plate original plate according to the embodiment, a lithographic printing plate having excellent plate skipping suppression property can be obtained, and further, the visibility of the exposed portion is also excellent.

18: Aluminum plate, 12a, 12b: Aluminum support, 20a, 20b: Anodized film, 22a, 22b: Micropore, 24: Large diameter hole, 26: Small diameter hole, 610: Anodizing device, 616: Aluminum plate, 618: electrolytic solution, 612: feeding tank, 614: electrolytic treatment tank, 616: aluminum plate, 620: feeding electrode, 622: roller, 624: nip roller, 626: electrolytic solution, 628: roller, 630: electrolytic electrode , 634: DC power supply

Claims (29)

It has a support and an image recording layer formed on the support.
The image recording layer contains a polymerizable compound A having an ethylenically unsaturated bond value of 5.0 mmol / g or more and a polymerizable compound B having a bifunctionality or less and a molecular weight of 1,000 or less. Print plate original plate. The machine-developed lithographic printing according to claim 1, wherein in the image recording layer, the ratio of the content of the polymerizable compound B to the total amount of the polymerizable compound A and the polymerizable compound B is 80% by mass or less. Original version. The machine-developed lithographic printing plate original plate according to claim 1 or 2, wherein the polymerizable compound B is a methacrylate compound. The machine-developed lithographic printing plate original plate according to any one of claims 1 to 3, wherein the polymerizable compound A is a compound represented by the following formula (I).
Equation (I): X- (Y) _n
In formula (I), X represents an n-valent organic group having a hydrogen-bonding group, Y represents a monovalent group having two or more ethylenically unsaturated groups, and n represents an integer of two or more. The molecular weight of X / (molecular weight of Y × n) is 1 or less. The machine according to claim 4, wherein the hydrogen-binding group in the polymerizable compound A contains at least one group selected from the group consisting of a urethane group, a urea group, an imide group, an amide group, and a sulfonamide group. Development type flat plate printing plate original plate. The on-board development type according to any one of claims 1 to 5, wherein the polymerizable compound A has at least one structure selected from the group consisting of an adduct structure, a biuret structure, and an isocyanate structure. Flat plate printing plate original plate. The on-machine development type according to any one of claims 1 to 6, wherein the polymerizable compound A has a structure represented by any of the following formulas (A-1) to (A-3). Planographic printing plate original plate.

In the formula (A-1), ^RA1 represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and the wavy line portion represents a bond position with another structure. The machine-developed lithographic printing plate original plate according to any one of claims 1 to 7, wherein the image recording layer further contains polyvinyl acetal. The machine-developed lithographic printing plate original plate according to claim 8, wherein the polyvinyl acetal has a content of a structural unit having a hydroxyl group of 15 mol% or more with respect to all the structural units in the polyvinyl acetal. The machine-developed lithographic printing plate original plate according to any one of claims 1 to 9, which has an outermost layer on the image recording layer. The machine-developed lithographic printing plate original plate according to claim 10, wherein the outermost layer contains a hydrophobic polymer. The machine-developed lithographic printing plate original plate according to claim 10 or 11, wherein the outermost layer contains a discolorable compound. The machine-developed lithographic printing plate original plate according to claim 12, wherein the brightness change ΔL before and after the exposure is 2.0 or more when exposure is performed by infrared rays having an energy density of 110 mJ / cm ^{2 and a wavelength of 830 nm.} The machine-developed lithographic printing plate original plate according to claim 12 or 13, wherein the discoloring compound contains a compound that develops color due to infrared exposure. The machine-developed lithographic printing plate original plate according to any one of claims 12 to 14, which contains a degradable compound in which the discolorable compound decomposes due to infrared exposure. The machine-developed lithographic printing plate original plate according to any one of claims 12 to 15, wherein the discoloring compound is a cyanine dye. The machine-developed lithographic printing plate original plate according to any one of claims 12 to 16, wherein the discolorable compound is a compound represented by the following formula 1-1.

In formula 1-1, R ¹ represents a group represented by any of the following formulas 2 to 4, and R ^{11 to} R ¹⁸ independently represent a hydrogen atom, a halogen atom, -R ^a , -OR ^b , and so on. Represents -SR ^c or -NR ^d R ^e , R ^{a to} R ^e each independently represent a hydrocarbon group, and A ₁ , A ₂ and a plurality of R _{11 to} R ₁₈ are linked to form a single ring or Polycycles may be formed, where A ₁ and A ₂ independently represent an oxygen atom, a sulfur atom, or a nitrogen atom, and n ₁₁ and n ₁₂ each independently represent an integer of 0 to 5. However, _{the total of n 11} and n ₁₂ is 2 or more, n ₁₃ and n ₁₄ independently represent 0 or 1, L represents an oxygen atom, a sulfur atom, or −NR ¹⁰ −, and R ¹⁰ Represents a hydrogen atom, an alkyl group, or an aryl group, and Za represents a counterion that neutralizes the charge.

In Formulas 2 to 4, R ²⁰ , R ³⁰ , R ⁴¹ and R ⁴² independently represent an alkyl group or an aryl group, Zb represents a counterion that neutralizes the charge, and the wavy line represents the above formula 1-. Represents a binding site with a group represented by L in 1. The machine-developed lithographic printing plate original plate according to claim 17, wherein the discolorable compound is a compound represented by the following formula 1-2.

In formula 1-2, R ¹ represents a group represented by any of the above formulas 2 to 4, and R ^{19 to} R ²² are independently hydrogen atom, halogen atom, -R ^a , -OR ^b , respectively. -CN, -SR ^c, or represents ^-NR d ^{R e, R 23} and ^{R 24} each independently represent a hydrogen atom, or represents a -R ^a, R ^a ~R ^e are each independently a hydrocarbon Representing a group, R ¹⁹ and R ²⁰ , R ²¹ and R ²² , or R ²³ and R ²⁴ may be linked to form a monocyclic or polycyclic, where L is an oxygen atom, a sulfur atom, or a hydrogen atom. , -NR ^10- , where R ¹⁰ represents a hydrogen atom, an alkyl group, or an aryl group, and R ^{d1 to} R ^d4 , W ¹ and W ² may each independently have a substituent. Represents an alkyl group and Za represents a counterion that neutralizes the charge. The machine-developed lithographic printing plate original plate according to any one of claims 17 or 18, wherein the discolorable compound is a compound represented by any of the following formulas 1-3 to 1-7.

In formulas 1-3 to 1-7, R ¹ represents a group represented by any of the above formulas 2 to 4, and R ^{19 to} R ²² are independently hydrogen atom, halogen atom, and −R ^a. , -OR ^b , -CN, -SR ^c , or -NR ^d R ^e , and R ²⁵ and R ^{26 independently represent a} hydrogen atom, a halogen atom, or -R a, and R ^{a to} R ^e. Represent each independently as a hydrocarbon group, and R ¹⁹ and R ²⁰ , R ²¹ and R ²² , or R ²⁵ and R ²⁶ may be linked to form a monocyclic or polycyclic, where L is. Represents an oxygen atom, a sulfur atom, or -NR ^10- , R ¹⁰ represents a hydrogen atom, an alkyl group, or an aryl group, and R ^{d1 to} R ^d4 , W ¹ and W ² are independent substituents. Represents an alkyl group which may have, and Za represents a counterion that neutralizes the charge. ^{W 1} and W ² in the formulas 1-2 to 1-7 are each independently an alkyl group having a substituent, and the substituents _{are-(OCH 2} CH ₂ )-, a sulfo group, and the like. The machine-developed flat plate printing plate original plate according to claim 18 or 19, which is a group having at least a sulfo group salt, a carboxy group, or a carboxy group salt. The image recording layer further contains a polymerization initiator and contains
The on-machine development type lithographic printing plate original plate according to any one of claims 1 to 20, wherein the polymerization initiator includes an electron donating type polymerization initiator and an electron accepting type polymerization initiator. The machine-developed lithographic printing plate original plate according to claim 21, wherein the polymerization initiator comprises a compound in which the electron-donating type polymerization initiator and the electron-accepting type polymerization initiator form an anti-salt. The machine-developed lithographic printing plate original plate according to claim 21, wherein the electron-accepting polymerization initiator contains a compound represented by the following formula (II).

In formula (II), X represents a halogen atom and R ³ represents an aryl group. The image recording layer contains an infrared absorber and contains
HOMO of the infrared absorber-The machine-developed lithographic printing plate original plate according to any one of claims 21 to 23, wherein the value of HOMO of the electron donating type polymerization initiator is 0.70 eV or less. The invention according to any one of claims 21 to 24, wherein the image recording layer contains an infrared absorber and the LUMO value of the electron-accepting polymerization initiator-LUMO of the infrared absorber is 0.70 eV or less. On-board development type lithographic printing plate original plate. The support has an aluminum plate and an aluminum anodic oxide film arranged on the aluminum plate.
The anodic oxide film is located closer to the image recording layer than the aluminum plate.
The anodic oxide film has micropores extending in the depth direction from the surface on the image recording layer side.
The machine-developed lithographic printing plate original plate according to any one of claims 1 to 25, wherein the average diameter of the micropores on the surface of the anodic oxide film is more than 10 nm and 100 nm or less. The micropore communicates with the large-diameter hole extending from the surface of the anodic oxide film to a depth of 10 nm to 1,000 nm and the bottom of the large-diameter hole, and has a depth of 20 nm to 2,000 nm from the communication position. It consists of a small-diameter hole that extends to the position.
The average diameter of the large-diameter hole portion on the surface of the anodic oxide film is 15 nm to 100 nm.
The machine-developed lithographic printing plate original plate according to claim 26, wherein the small diameter hole portion has an average diameter of 13 nm or less at the communication position. A step of exposing the machine-developed lithographic printing plate original plate according to any one of claims 1 to 27 to an image.
A method for producing a lithographic printing plate, comprising a step of supplying at least one selected from the group consisting of printing ink and dampening water on a printing machine to remove an image recording layer in a non-image area. A step of exposing the machine-developed lithographic printing plate original plate according to any one of claims 1 to 27 to an image.
A process of supplying at least one selected from the group consisting of printing ink and dampening water on a printing machine to remove the image recording layer in the non-image area to produce a lithographic printing plate.
Including the process of printing with the obtained lithographic printing plate,
Planographic printing method.

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