JP2020140012A - Positive lithographic printing original plate and method for producing lithographic printing plate - Google Patents

Abstract

To provide a positive lithographic printing original plate excellent in abrasion suppressing property, and a method for producing a lithographic printing plate using the positive lithographic printing original plate excellent in abrasion suppressing property.SOLUTION: The positive lithographic printing original plate has a support and an image recording layer provided on the support. The image recording layer includes a binder polymer A which has a structural unit having an acid group having a pKa of 9 or less, a binder polymer B which has a structural unit having a base group, and an infrared absorber. A total content of the binder polymer A and the binder polymer B is 10 mass% or more with respect to a total mass of the whole binder polymer in the image recording layer. The method for producing the lithographic printing plate includes the steps of: image exposing the positive lithographic printing original plate; and developing the exposed positive lithographic printing original plate with the use of a developer having pH of 10.0 or less, in this order.SELECTED DRAWING: None

Description

The present disclosure relates to a positive lithographic printing plate original plate and a method for producing a lithographic printing plate.

In general, a lithographic printing plate has a lipophilic image portion that receives ink in the printing process and a hydrophilic non-image portion that receives dampening water. In lithographic printing, utilizing the property that water and oil-based ink repel each other, the oil-based image part of the lithographic printing plate is the ink receiving part, and the hydrophilic non-image part is the dampening water receiving part (ink non-receiving part). This is a method in which a difference in the adhesiveness of ink is generated on the surface of a lithographic printing plate, the ink is inlaid only on the image portion, and then the ink is transferred to a printing object such as paper for printing. The lithographic printing plate includes, for example, a support and an image recording layer formed on the support by a method such as applying a photosensitive resin composition containing a polymer compound and a solvent onto the support and drying the support. It is manufactured by developing a lithographic printing plate original plate.

As a composition used for producing a flat plate printing plate original plate, Patent Document 1 describes (A) a structural unit having an acid group bonded to a side chain via an organic linking group, and an amide group and an amino group to the side chain. A photosensitive composition comprising a structural unit having at least one, a polymer compound having, and (B) an infrared absorber is disclosed.

Further, Patent Document 2 describes a laminate of a lithographic printing plate material in which an interleaving paper is laminated on the image forming layer of a positive lithographic printing plate material having an image forming layer containing an infrared absorbing compound on an aluminum support. The lithographic printing plate material laminate is disclosed, wherein the image forming layer contains an acrylic resin having a fluoroalkyl group, and the Clark rigidity in the vertical grain direction of the interleaving paper is 30 or less. Has been done.

Japanese Unexamined Patent Publication No. 2004-361483 JP-A-2009-045852

In the positive lithographic printing plate original plate, for example, unlike the negative lithographic printing plate original plate in which the exposed portion is cured, ablation may occur when exposed. Ablation is a phenomenon in which the image recording layer explosively expands due to heat generated during exposure, and the image recording layer is removed by volatilization or decomposition. When the above ablation occurs, there may be a problem that the optical system is contaminated by scattered substances such as components of the image recording layer. For this reason, ablation is required to be suppressed in the positive lithographic printing plate original plate.

However, there is room for further improvement in the photosensitive composition described in Patent Document 1 and the laminate of the lithographic printing plate material described in Patent Document 2 from the viewpoint of ablation inhibitory property.

One aspect of the present disclosure is to provide a positive lithographic printing plate original plate having excellent ablation inhibitory properties.
Another aspect of the present disclosure is to provide a method for producing a lithographic printing plate using a positive lithographic printing plate original plate having excellent ablation inhibitory properties.

Means for solving the above problems include the following aspects.
<1> A structure having a support, an image recording layer on the support, and the binder polymer A having a structural unit having an acid group having a pKa of 9 or less and a base group. It contains a binder polymer B having a unit and an infrared absorber, and the total content of the binder polymer A and the binder polymer B is 10 with respect to the total mass of all the binder polymers in the image recording layer. Positive type lithographic printing plate original plate with mass% or more.
<2> The positive lithographic printing plate original plate according to <1>, wherein the structural unit having the above base group is a structural unit represented by the following formula B1, the following formula B2, or the following formula B3.

In formula B1, R ¹ represents a hydrogen atom or a methyl group, X ¹ represents a single bond, an ester bond or an amide bond, L ¹ represents a single bond or a divalent linking group, and Base represents a base group. Atoms contained in L ¹ and Base may form a ring, and * independently represents a bonding site with another structure.
In formula B2, Y ¹ and Y ² independently represent -O- or -NR-, R represents a hydrogen atom or an alkyl group, A ¹ represents a trivalent linking group, and L ² is a single bond. Alternatively, it represents a divalent linking group, Base represents a base group, and A ¹ or L ² may be bonded to an atom contained in Base to form a ring, and * indicates an independent structure with another structure. Represents the binding site of.
In formula B3, Y ³ and Y ⁴ independently represent -O- or -NR-, R represents a hydrogen atom or an alkyl group, and L ³ and L ⁴ independently represent a single bond or divalent, respectively. Representing a linking group, Base represents a base group, and at least one of L ³ and L ⁴ may be bonded to an atom contained in Base to form a ring, and L ³ and L ⁴ may be bonded to each other to form a ring. May be formed, and each independently represents a binding site with another structure.

<3> The positive lithographic printing plate original plate according to <1> or <2>, wherein the base group is a group having a piperidine ring.
<4> The positive type according to any one of <1> to <3>, wherein the structural unit having an acid group having a pKa of 9 or less is a structural unit represented by the following formula A1 or the following formula A2. Planographic printing plate original plate.

In formula A1, R ^1A represents a hydrogen atom or a methyl group, X ^1A represents a single bond, an ester bond or an amide bond, L ^1A represents a single bond or a divalent linking group, and Acid has a pKa of 9 or less. It represents an acid group, and * represents a binding site with another structure independently.
In formula A2, Y ^1A and Y ^2A independently represent -O- or -NR-, R represents a hydrogen atom or an alkyl group, A ^1A represents a trivalent linking group, and L ^2A is a single bond. Alternatively, it represents a divalent linking group, Acid represents an acid group having a pKa of 9 or less, and * represents a binding site with another structure independently.

<5> The positive lithographic printing plate original plate according to any one of <1> to <4>, wherein the pKaH of the base group is 8 to 11.
<6> The positive lithographic printing plate original plate according to any one of <1> to <5>, wherein the ClogP of the structural unit having the above base group is 1 to 5.
<7> to a substance quantity _{N A} of the acid groups of the pKa of 9 or less in the binder polymer A, the ratio _N B / _{N A} substance quantity _{N B} of the base groups in the binder polymer B is 1/2 to 2 The positive type lithographic printing plate original plate according to any one of <1> to <6>, which is / 1.
<8> The positive lithographic printing plate original plate according to any one of <1> to <7>, wherein the pKa of the acid group is 3 to 6.
<9> The positive lithographic printing plate original plate according to any one of <1> to <8>, wherein the acid group is a carboxy group.
<10> Any of <1> to <9> in which the total content of the binder polymer A and the binder polymer B is 50% by mass or more with respect to the total mass of all the binder polymers in the image recording layer. The original plate of the positive type lithographic printing plate described in one.
<11> The image recording layer includes a lower layer and an upper layer, and at least one of the lower layer and the upper layer contains the binder polymer A, the binder polymer B, and the infrared absorber <1> to <. The positive type planographic printing plate original plate according to any one of 10>.
<12> The image recording layer includes a lower layer and an upper layer, one of the lower layer and the upper layer contains the binder polymer A, and the other of the lower layer and the upper layer contains the binder polymer B <1>. The positive type planographic printing plate original plate according to any one of ~ <10>.
<13> The step of image-exposing the positive lithographic printing plate original plate according to any one of <1> to <12> and the exposed positive lithographic printing plate original plate with a developer having a pH of 10.0 or less. A method for producing a lithographic printing plate, which includes a step of developing using and in this order.

According to one aspect of the present disclosure, it is possible to provide a positive lithographic printing plate original plate having excellent ablation inhibitory properties.
According to another aspect of the present disclosure, it is possible to provide a method for producing a lithographic printing plate using a positive lithographic printing plate original plate having excellent ablation inhibitory properties.

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 another numerical range described stepwise. .. Further, in the numerical range described in the present disclosure, the upper limit value or the lower limit value of the numerical range may be replaced with the value shown in the examples.
Further, in the present disclosure, the amount of each component in the composition is the total amount of the plurality of applicable substances present in the composition unless otherwise specified, when a plurality of substances corresponding to each component are present in the composition. Means.
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 methacryloyl. is there.
Further, in the present disclosure, regarding the notation of a group in the compound represented by the formula, there is no other specification unless a substituted or unsubstituted group is described, or when the group can further have a substituent. As long as the group includes not only an unsubstituted group but also a group having a substituent. For example, if there is a description in the formula that "R represents an alkyl group, an aryl group or a heterocyclic group", "R is an unsubstituted alkyl group, a substituted alkyl group, an unsubstituted aryl group, a substituted aryl group or an unsubstituted" It means "representing a heterocyclic group or a substituted heterocyclic group".
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.
Unless otherwise specified, the weight average molecular weight (Mw) and the number average molecular weight (Mn) in the present disclosure use columns of TSKgel GMHxL, TSKgel G4000HxL, and TSKgel G2000HxL (all of which are trade names manufactured by Toso Co., Ltd.). The molecular weight is detected by the solvent THF (tetrahydrofuran) and the differential refraction meter by the gel permeation chromatography (GPC) analyzer, and is converted by using polystyrene as a 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 as necessary, but also a discarded plate. In the case of a discarded original plate, exposure and development operations are not always necessary. The discard plate is a planographic printing plate original plate to be attached to an unused plate cylinder when printing a part of the paper surface in a single color or two colors in, for example, color newspaper printing.

In the present disclosure, the "main chain" represents a relatively longest binding chain among the molecules of the polymer compound constituting the resin, and the "side chain" represents an atomic group branched from the main chain.
Hereinafter, the present disclosure will be described in detail.

<Positive planographic printing plate original>
The positive lithographic printing plate original plate according to the present disclosure (hereinafter, also simply referred to as "lithographic printing plate original plate") has a support and an image recording layer on the support, and the image recording layer is a support. Binder polymer A having a structural unit having an acid group of pKa of 9 or less, binder polymer B having a structural unit having a basic group, and an infrared absorber, the binder polymer A and the binder polymer B. The total content of is 10% by mass or more with respect to the total mass of all the binder polymers in the image recording layer. Hereinafter, the binder polymer A and the binder polymer B may be collectively referred to as a "specific binder polymer".

The positive lithographic printing plate original plate according to the present disclosure has the above configuration and is excellent in ablation inhibitory property. The reason why the positive lithographic printing plate original plate according to the present disclosure exerts the above effect is not clear, but it is presumed as follows.
The polymer compound used in Patent Document 1 has a structural unit having an acid group bonded to the side chain (A) via an organic linking group in the same chemical structure, and at least an amide group and an amino group in the side chain. It has a structural unit having one and the other. Further, the acrylic resin having a fluoroalkyl group used in Patent Document 2 has a base group and an acid group in the same structural unit. However, it is considered that the image recording layer containing the polymer compound or the acrylic resin cannot sufficiently suppress the occurrence of ablation because the film has insufficient fastness.
On the other hand, in the image recording layer of the positive lithographic printing plate original plate according to the present disclosure, the acid group in the binder polymer A and the base group in the binder polymer B form a salt, so that the image recording layer becomes stronger. I can think of it. As a result, it is presumed that the ablation inhibitory property is excellent because the volatilization of the components in the image recording layer at the time of exposure can be suppressed.

Hereinafter, details of each configuration included in the positive lithographic printing plate original plate according to the present disclosure will be described.

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

As the support in the present disclosure, a polyester film or an aluminum plate is preferable, and among the above, an aluminum plate having good dimensional stability and being relatively inexpensive is particularly preferable. A suitable aluminum plate is a pure aluminum plate or an alloy plate containing aluminum as a main component and containing a trace amount of a foreign element (that is, an element other than aluminum). A suitable aluminum plate may be a plastic film in which aluminum is laminated or vapor-deposited. Examples of the foreign element contained in the aluminum alloy include silicon, iron, manganese, copper, magnesium, chromium, zinc, bismuth, nickel, and titanium. The content of the foreign element in the alloy is preferably 10% by mass or less with respect to the total mass of the support.

A particularly suitable aluminum in the present disclosure is pure aluminum, but completely pure aluminum may contain a slight amount of different elements because it is difficult to produce completely pure aluminum due to refining technology.

As described above, the composition of the aluminum plate applied to the present disclosure is not specified, and an aluminum plate made of a conventionally known public material can be appropriately used.

The thickness of the aluminum plate used in the present disclosure is preferably 0.1 mm to 0.6 mm, more preferably 0.15 mm to 0.4 mm, and particularly preferably 0.2 mm to 0.3 mm. preferable.

If necessary, the aluminum plate may be subjected to surface treatment such as roughening treatment and anodic oxidation treatment. Regarding the surface treatment of the aluminum support, for example, a degreasing treatment with a surfactant, an organic solvent, an alkaline aqueous solution or the like, as described in detail in paragraphs 0167 to 0169 of JP2009-175195A, and surface roughness. Surface treatment, anodization treatment, etc. are appropriately performed.
The anodized aluminum surface is hydrolyzed, if necessary.
As the hydrophilization treatment, a method of treating with an alkali metal silicate (for example, an aqueous sodium silicate solution) method, potassium fluoride zirconate, or polyvinylphosphonic acid as disclosed in paragraph 0169 of JP2009-175195A. Etc. are used.
Further, the support described in Japanese Patent Application Laid-Open No. 2011-245844 is also preferably used.

[Image recording layer]
The lithographic printing plate original plate according to the present disclosure has an image recording layer. The image recording layer contains a binder polymer A having a structural unit having an acid group having a pKa of 9 or less, a binder polymer B having a structural unit having a base group, and an infrared absorber. Further, the total content of the binder polymer A and the binder polymer B is 10% by mass or more with respect to the total mass of all the binder polymers in the image recording layer. In the image recording layer in the lithographic printing plate original plate according to the present disclosure, the image recording layer becomes stronger by forming a salt between the acid group in the binder polymer A and the base group in the binder polymer B. As a result, volatilization of the components in the image recording layer at the time of exposure can be suppressed, so that the lithographic printing plate original plate according to the present disclosure is excellent in ablation suppressing property.

The salt formed in the image recording layer is thermally decomposed by the heat generated during exposure. When the salt is thermally decomposed, an acid group having a pKa of 9 or less appears. As a result, the exposed portion (that is, the non-image portion) of the image recording layer has increased solubility in the developing solution. On the other hand, in the non-exposed portion (that is, the image portion) of the image recording layer, the penetration of the developing solution is suppressed by the formation of the salt.

[Binder polymer A]
The image recording layer in the present disclosure contains a binder polymer A having a structural unit having an acid group having a pKa of 9 or less. The binder polymer A is a binder polymer different from the binder polymer B. The binder polymer A contained in the image recording layer may be one type alone or two or more types.

The binder polymer A may be an addition polymerization type resin, a polyaddition type resin, or a polycondensation type resin. Among the above, the binder polymer A is preferably an addition polymerization type resin, more preferably a resin obtained by polymerizing an ethylenically unsaturated compound, and acrylic from the viewpoint of resolution and ease of production. It is particularly preferably a resin. As the acrylic resin, a resin having a content of a structural unit formed of the (meth) acrylic compound of 50% by mass or more is preferable. Further, the addition polymerization type resin, the heavy addition type resin, or the polycondensation type resin is preferably a linear resin.

Further, the binder polymer A is preferably an alkali-soluble resin, and more preferably a weak alkali-soluble resin soluble in a weak alkali.

In the present disclosure, "alkali-soluble" means soluble in a 1 mol / L sodium hydroxide solution at 25 ° C.
In the present disclosure, "weakly alkaline soluble" means soluble in 0.0001 mol / L sodium hydroxide solution (pH 10) at 25 ° C.
In the present disclosure, "soluble" means that 0.1 g or more is dissolved in 100 mL of a solvent.

(Constituent unit having an acid group with pKa of 9 or less)
The binder polymer A has a structural unit having an acid group having a pKa of 9 or less (hereinafter, also referred to as “constituent unit A”).

-Acid group-
The acid group in the structural unit A is not limited as long as the pKa is 9 or less, and examples thereof include a carboxy group, a sulfo group, a phosphoric acid group, a phosphonic acid group, and a sulfate group. Among the above, the acid group is preferably a carboxy group from the viewpoint of image retention and printing resistance.

The sulfonamide group (-SO _2- NH- or -SO _2- NH ₂ ), phenolic hydroxyl group, etc. usually has a pKa of more than 9, so that the acid group of the binder polymer A has a pKa of 9 or less. Is not included. The binder polymer A may have an acid group having a pKa of more than 9, but the content of the acid group having a pKa of more than 9 is 0, based on the total mass of the binder polymer A from the viewpoint of developability. It is preferably 1 mol / g or less, and more preferably 0.01 mol / g or less.

-PKa-
The pKa of the acid group in the structural unit A is 9 or less, preferably 7 or less, more preferably 6 or less, still more preferably 5.5 or less, from the viewpoint of developability. The following is particularly preferable.

The lower limit of the pKa of the acid group in the structural unit A is preferably -5 or more, more preferably 0 or more, and further preferably 2 or more, from the viewpoint of image retention and printing resistance. It is preferably 3 or more, and most preferably 4 or more.

In the present disclosure, pKa is calculated using ACD / pKa DB ver 8.07 of ACD / Labs software Ver 8.0 for Microsoft windows manufactured by Advanced Chemistry Development.

-LogP-
The ClogP of the structural unit A is preferably -2 to 5, more preferably 0 to 5, and preferably 1 to 5 from the viewpoint of developability, image retention, and print resistance. More preferably, it is particularly preferably 1 to 4, and most preferably 2 to 3.8.

In the present disclosure, ClogP is a value obtained by calculating the common logarithm logP of 1-octanol and the partition coefficient P to water.
As for the method and software used for the calculation of ClogP, known ones can be used, but unless otherwise specified, the ClogP program incorporated in ChemBioDrow Ultra 12.0 of Cambridge Soft Co., Ltd. is used in this disclosure.

Further, in the calculation of ClogP of the structural unit A, the connection site (for example, * in the following structural unit UA-1) of the target structural unit (preferably the monomer unit) is replaced with a hydrogen atom for calculation.
For example, when calculating the ClogP of the following structural unit UA-1, the ClogP is calculated after converting the following structural unit UA-1 into a structure represented by the following UA'-1.

-Structure-
The structure of the structural unit A is not limited as long as it contains an acid group having a pKa of 9 or less. The structural unit A is preferably a structural unit represented by the following formula A1 or the following formula A2 from the viewpoints of resolution, image retention, printing resistance, and ablation inhibitory property, and is preferably represented by the following formula A1. It is more preferable that the structural unit is represented.

In formula A1, R ^1A represents a hydrogen atom or a methyl group, X ^1A represents a single bond, an ester bond or an amide bond, L ^1A represents a single bond or a divalent linking group, and Acid has a pKa of 9 or less. It represents an acid group, and * represents a binding site with another structure independently.
In formula A2, Y ^1A and Y ^2A independently represent -O- or -NR-, R represents a hydrogen atom or an alkyl group, A ^1A represents a trivalent linking group, and L ^2A is a single bond. Alternatively, it represents a divalent linking group, Acid represents an acid group having a pKa of 9 or less, and * represents a binding site with another structure independently.

A specific embodiment of the structural unit represented by the formula A1 will be described below.

In the formula A1, X ^1A represents a single bond, an ester bond (-C (= O) O-) or an amide bond (-C (= O) NH-), and is preferably an ester bond or an amide bond.
When the X ^1A represents an ester bond, it is preferable that the carbon atom in the ester bond is bonded to the main chain side of the binder polymer A (that is, the carbon atom to which R ^1A is bonded).
When the X ^1A represents an amide bond, it is preferable that the carbon atom in the amide bond is bonded to the main chain side of the binder polymer A (that is, the carbon atom to which R ^1A is bonded).
In the formula A1, L ^1A represents a single bond or a divalent linking group, and is preferably a divalent hydrocarbon group which may have a single bond or an ester bond or an ether bond inside, and is preferably a single bond or a divalent hydrocarbon group. It is more preferably a divalent hydrocarbon group, and particularly preferably a single bond or a divalent aliphatic saturated hydrocarbon group.
When the above L ^1A represents a divalent hydrocarbon group, the number of carbon atoms of L ^1A is preferably 2 or more, more preferably 2 to 15, and particularly preferably 3 to 12.
In the formula A1, Acid represents an acid group having a pKa of 9 or less, and is preferably a carboxy group.
In the formula A1, the preferable numerical range of pKa of the acid group represented by Acid is the same as the numerical range described in the above section “pKa”.

Next, a specific embodiment of the structural unit represented by the formula A2 will be described below.

In the formula A2, Y ^1A and Y ^2A are preferably −O− or −NR−, respectively.
In the formula A2, when at least one of Y ^1A and Y ^2A represents -NR-, R is preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and more preferably a hydrogen atom or a methyl group. , A hydrogen atom is particularly preferable.
In the formula A2, ^A1A represents a trivalent linking group, preferably a trivalent hydrocarbon group, and more preferably a trivalent aliphatic saturated hydrocarbon group.
In the formula ^A2, the number of carbon atoms of ^{A 1A} is preferably 1 or more, more preferably 1 to 10, and particularly preferably from 3 to 10.
In the formula A2, L ^2A represents a single bond or a divalent linking group, preferably a single bond or a divalent hydrocarbon group, and preferably a single bond or a divalent aliphatic saturated hydrocarbon group.
When the above L ^2A represents a divalent hydrocarbon group, the number of carbon atoms of L ^2A is preferably 1 or more, more preferably 1 to 10, and particularly preferably 3 to 10.
In the formula A2, Acid represents an acid group having a pKa of 9 or less, and is preferably a carboxy group.
In the formula A2, the preferable numerical range of pKa of the acid group represented by Acid is the same as the numerical range described in the above section “pKa”.
In formula A2, * independently constitutes an ester bond or amide bond containing Y ^1A or Y ^2A by binding to a bond represented by −C (= O) − of another structural unit, or It is preferable to form a urethane bond or a urea bond containing Y ^1A or Y ^2A by binding to a bond represented by the other structural unit -C (= O) NH-, and the other structural unit -C ( = O) It is more preferable to form a urethane bond or a urea bond containing Y ^1A or Y ^2A by binding to the bond represented by NH−.
In the formula A2, it is preferable that the molecular chain composed of Y ^1A , A ^1A and Y ^2A is contained in the main chain of the binder polymer A.

Next, a preferred embodiment of the structural unit represented by the formula A1 and the structural unit represented by the formula A2 will be described.

The structural unit represented by the formula A1 is preferably the structural unit represented by the following formula a1.

In formula a1, R ^2A represents a hydrogen atom or a methyl group, X ^2A represents an -O- or -NR-, R represents a hydrogen atom or an alkyl group, and L ^3A is a single bond or one or more carbon atoms. Represents the divalent hydrocarbon group of, and * represents the bonding site with other structures independently.

In the formula a1, when X ^2A represents −NR−, R is preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, more preferably a hydrogen atom or a methyl group, and is a hydrogen atom. Is particularly preferable.
In the formula a1, L ^3A is preferably a single bond or a divalent aliphatic saturated hydrocarbon group having 1 or more carbon atoms.
In the formula a1, when L ^3A represents a divalent hydrocarbon group having 1 or more carbon atoms, the carbon number of L ³ is preferably 2 to 15 and more preferably 3 to 12.
In formula a1, COOH (carboxy group) is an acid group having a pKa of 9 or less.

The structural unit represented by the formula A2 is preferably the structural unit represented by the following formula a2.

In formula a2, Y ^3A and Y ^4A independently represent -O- or -NH-, A ^2A represents a trivalent hydrocarbon group having 1 or more carbon atoms, and L ^4A is a single bond or 1 carbon atom. Representing the above divalent hydrocarbon groups, * is independently bonded to the bond represented by the other structural unit -C (= O) NH-, and is a urethane bond containing Y ^3A or Y ^4A. Consists of urea bonds.

In the formula a2, ^A2A is preferably a trivalent aliphatic saturated hydrocarbon group having 1 or more carbon atoms.
In the formula a2, the carbon number of A ^2A is preferably 1 to 10 and more preferably 3 to 10.
In the formula a2, L ^4A is preferably a single bond or an aliphatic saturated hydrocarbon group having 1 or more carbon atoms.
In the formula a2, when L ^4A represents a divalent hydrocarbon group having 1 or more carbon atoms, the carbon number of L ^4A is preferably 1 to 10 and more preferably 3 to 10.
In formula a2, COOH (carboxy group) is an acid group having a pKa of 9 or less.
Further, in the formula a2, it is preferable that the molecular chain composed of Y ^3A , A ^2A and Y ^4A is contained in the main chain of the binder polymer A.

A specific example of the structural unit A is shown below. However, the structural unit A is not limited to the following structural units.

The structural unit A in the binder polymer A may be one type alone or two or more types.

The content of the structural unit A in the binder polymer A is 5% by mass to 70% by mass with respect to the total mass of the binder polymer A from the viewpoints of developability, image retention, printing resistance, and ablation suppression property. It is preferably 10% by mass to 65% by mass, further preferably 20% by mass to 60% by mass, and particularly preferably 25% by mass to 60% by mass.

Examples of the method for introducing the structural unit A into the binder polymer A include a method using a monomer having an acid group having a pKa of 9 or less as a raw material. Examples of the monomer include 11-acrylamide undecanoic acid, 6-acrylamide hexanoic acid, 2-methacryloyloxyethyl succinic acid, 2-acryloyloxyethyl hexahydrophthalic acid, ω-carboxy-polycaprolactone monoacrylate, methacrylic acid and acrylic. Acids, 4-vinylbenzoic acid, 2-acryloyloxyethyl acid phosphate, 2-acrylamide-2-methylpropanesulfonic acid, and dimethylpropionic acid can be mentioned.

(Other building blocks)
The binder polymer A preferably has another structural unit in addition to the structural unit (constituent unit A) having an acid group having a pKa of 9 or less. The other structural unit in the binder polymer A is a structural unit that does not correspond to the structural unit A.

When the binder polymer A is an addition polymerization type resin, other structural units include, for example, a structural unit formed of a (meth) acrylic acid ester compound, (meth) acrylamide, or a styrene compound. Among the above, a structural unit formed of a (meth) acrylic ester compound is preferable, and a structural unit formed of a (meth) acrylic acid ester compound having no hydrophilic group is preferable from the viewpoint of ink inking property and scratch resistance. Is more preferable.

The (meth) acrylic acid ester compound may be a monofunctional (meth) acrylic acid ester compound having one (meth) acryloxy group in one molecule, or two or more (meth) acrylic acid ester compounds in one molecule. Although it may be a polyfunctional (meth) acrylic acid ester compound having an acryloxy group, it is preferably a monofunctional (meth) acrylic acid ester compound from the viewpoint of developability.

From the viewpoint of ink penetration and scratch resistance, the (meth) acrylic acid ester compound is preferably a monofunctional (meth) acrylic acid ester compound which does not have a hydrophilic group and has a hydrophilic group. A monofunctional methacrylic acid ester compound is more preferable.

Examples of the monofunctional methacrylic acid ester compound having no hydrophilic group include methacrylic acid alkyl ester and methacrylic acid cyclic alkyl ester. The methacrylic acid ester compound may have a substituent other than the hydrophilic group.

Among the above, an alkyl methacrylate ester having an alkyl group having 1 to 12 carbon atoms is preferable from the viewpoint of image retention and printing resistance.
Examples of the methacrylic acid alkyl ester having an alkyl group having 1 to 12 carbon atoms include methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, and benzyl methacrylate.
Among the above, methyl methacrylate is preferable.

The structural unit formed by the (meth) acrylic acid ester compound in the binder polymer A may be one kind alone or two or more kinds.

The content of the structural unit formed by the (meth) acrylic acid ester compound other than the structural unit A is preferably 35% by mass to 90% by mass, preferably 40% by mass to 90% by mass, based on the total mass of the binder polymer A. It is more preferably 80% by mass, and particularly preferably 40% by mass to 75% by mass.

Further, for example, when the binder polymer A is a polyaddition type resin or a polycondensation type resin, the other structural units are formed of a polyvalent isocyanate compound and a polyhydric carboxylate compound. Examples include a structural unit formed of a polyhydric alcohol compound, a structural unit formed of a polyhydric alcohol compound, and a structural unit formed of a polyhydric amine compound. Further, the binder polymer A may have an alkylene group described later.

As the multivalent isocyanate compound, a diisocyanate compound is preferable.
As the polyvalent carboxylate compound, a dicarboxylic acid salt compound is preferable.
As the polyhydric alcohol compound, a diol compound is preferable.
As the multivalent amine compound, a diamine compound is preferable.

-Multivalent isocyanate compound-
Examples of the polyisocyanate compound include 1,3-bis (isocyanatomethyl) cyclohexane, isophorone diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, 1,3-cyclopentane diisocyanate, and 9H-. Fluoren-2,7-diisocyanate, 9H-fluoren-9-on-2,7-diisocyanate, 4,4'-diphenylmethane diisocyanate, 1,3-phenylenediisocyanate, trilen-2,4-diisocyanate , Trilen-2,6-diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, 2,2-bis (4-isocyanatophenyl) hexafluoropropane, and 1,5-diisocyanatonaphthalene. Be done.

The structural unit formed by the multivalent isocyanate compound in the binder polymer A may be one kind alone or two or more kinds.

The content of the structural unit formed by the polyhydric isocyanate compound is preferably 10% by mass to 60% by mass, more preferably 20% by mass to 50% by mass, based on the total mass of the binder polymer A. preferable.

-Polyvalent carboxylic acid salt compound-
Examples of the polyvalent carboxylic acid salt compound include a polyvalent carboxylic acid halide compound (for example, a polyvalent carboxylic acid chloride compound) and a polyvalent carboxylic acid ester compound. Specific examples of the polyvalent carboxylate compound include the following CL-1 to CL-10.

The structural unit formed by the polyvalent carboxylate compound in the binder polymer A may be one kind alone or two or more kinds.

The content of the structural unit formed by the polyvalent carboxylate compound is preferably 10% by mass to 60% by mass, preferably 20% by mass to 40% by mass, based on the total mass of the binder polymer A. Is more preferable.

-Multivalent alcohol compounds-
Examples of the polyhydric alcohol compound include ethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, and 1,8-octanediol. Included are 1,9-nonanediol, 1,10-decanediol, neopentyl glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, 1,4-cyclohexanedimethanol, and 3-methyl-1,5-pentanediol. Be done.

The structural unit formed by the polyhydric alcohol compound in the binder polymer A may be one kind alone or two or more kinds.

The content of the structural unit formed by the polyhydric alcohol compound is preferably 0% by mass to 40% by mass, and more preferably 1% by mass to 30% by mass, based on the total mass of the binder polymer A. preferable.

-Multivalent amine compound-
Examples of the polyvalent amine compound include 2,7-diamino-9H-fluorene, 2,2-bis (4-aminophenyl) hexafluoropropane, 4,4'-diaminobenzophenone, and bis (4-aminophenyl) sulfone. , 4,4'-diaminodiphenyl ether, bis (4-aminophenyl) sulfide, 1,1-bis (4-aminophenyl) cyclohexane, 4,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 3,3 '-Diaminobenzophenone, 4,4'-diamino-3,3'-dimethyldiphenylmethane, 1,5-diaminonaphthalene, 1,3-phenylenediamine, 2,4-diaminotoluene, 2,6-diaminotoluene, 1, 8-diaminonaphthalene, 1,3-diaminopropane, 1,3-diaminopentane, 2,2-dimethyl-1,3-propanediamine, 1,5-diaminopentane, 2-methyl-1,5-diaminopentane, Included are 1,7-diaminoheptane, 1,3-diamino-2-propanol, diethylene glycol bis (3-aminopropyl) ether, m-xylylene diamine, and 1,3-bis (aminomethyl) cyclohexane.

The structural unit formed by the polyvalent amine compound in the binder polymer A may be one kind alone or two or more kinds.

The content of the structural unit formed by the polyvalent amine compound is preferably 0% by mass to 40% by mass, and more preferably 1% by mass to 20% by mass, based on the total mass of the binder polymer A. preferable.

-Constituent unit having a base group-
Further, the binder polymer A may have a structural unit having a base group, but preferably does not have a structural unit having a base group.
Examples of the base group include the base groups described in the section of "Binder Polymer B" described later.
The content of the structural unit having a base group is preferably 10% by mass or less, preferably 5% by mass or less, and preferably 1% by mass or less, based on the total mass of the binder polymer A. , 0% by mass is preferable.

-Ethylenedioxy group-
Further, the binder polymer A may have an alkyleneoxy group. Examples of the method for introducing a polyalkyleneoxy group into the binder polymer A include a method using the above-mentioned polyhydric alcohol.

As the alkyleneoxy group, an alkyleneoxy group having 2 to 10 carbon atoms is preferable, an alkyleneoxy group having 2 to 8 carbon atoms is more preferable, an alkyleneoxy group having 2 to 4 carbon atoms is further preferable, an ethyleneoxy group or propylene. Oxy groups are particularly preferred.

Further, the alkyleneoxy group may be a polyalkyleneoxy group.
As the polyalkyleneoxy group, a polyalkyleneoxy group having a repetition number of 2 to 50 is preferable, a polyalkyleneoxy group having a repetition number of 2 to 40 is more preferable, and a polyalkyleneoxy group having a repetition number of 2 to 30 is particularly preferable.
The preferable carbon number of the alkyleneoxy group in the structural unit having a polyalkyleneoxy group is the same as the preferable carbon number of the alkyleneoxy group.
The structural unit having an alkyleneoxy group is introduced, for example, by using a polyalkylene glycol compound (for example, polyethylene glycol or polypropylene glycol) as the polyhydric alcohol compound. The polyalkylene glycol compound is also available as, for example, Uniol (registered trademark) D-1200 manufactured by NOF CORPORATION.

(Acid value)
The acid value of the binder polymer A is preferably 0.5 meq / g to 4 meq / g, preferably 1.2 meq / g to 3 from the viewpoint of developability, image retention, printing resistance, and ablation inhibitory property. .2 meq / g is more preferable, 1.4 meq / g to 2.5 meq / g is further preferable, 1.5 meq / g to 2 meq / g is particularly preferable, and 1.5 meq / g. Most preferably, it is ~ 1.8 meq / g. In the present disclosure, the acid value is represented by the number of moles of potassium hydroxide required to neutralize 1 g of a sample, and is measured by a method according to JIS standard (JIS K0070: 1992).

(Weight average molecular weight)
The weight average molecular weight (Mw) of the binder polymer A is preferably more than 5,000 and less than 200,000, and more than 10,000 and less than 100,000 from the viewpoint of developability and print resistance. Is more preferable, and 12,000 to 50,000 is particularly preferable.

(Production method)
The method for producing the binder polymer A is not limited, and a known method can be applied. For example, a binder polymer A can be obtained as a polymer by applying energy by heating or exposure using a composition containing a monomer forming each structural unit and a known polymerization initiator. The composition may further contain known additives. The detailed conditions for applying energy may be determined with reference to known documents.

[Binder polymer B]
The image recording layer in the present disclosure contains a binder polymer B having a structural unit having a base group. The binder polymer B is a binder polymer different from the binder polymer A. The binder polymer B contained in the image recording layer may be one kind alone or two or more kinds.

The binder polymer B may be an addition polymerization type resin, a polyaddition type resin, or a polycondensation type resin. Among the above, the binder polymer A is preferably an addition polymerization type resin, more preferably a resin obtained by polymerizing an ethylenically unsaturated compound, and acrylic from the viewpoint of resolution and ease of production. It is particularly preferably a resin. As the acrylic resin, a resin having a content of a structural unit formed of the (meth) acrylic compound of 50% by mass or more is preferable.

(Constituent unit having a base group)
The binder polymer B has a structural unit having a base group (hereinafter, also referred to as “constituent unit B”).

-Base group-
The base group is not limited, and a known base group can be applied. The base group is preferably a group having a nitrogen atom. The group having a nitrogen atom is preferably an amino group, an alkylamino group, a dialkylamino group, a group having a nitrogen-containing aliphatic ring, or a group having a nitrogen-containing aromatic ring, and is preferably a dialkylamino group or a nitrogen-containing aliphatic ring. It is more preferable that the group has a nitrogen-containing aromatic ring, more preferably a dialkylamino group, or a group having a nitrogen-containing aliphatic ring, and a group having a nitrogen-containing aliphatic ring. Is particularly preferable.

The alkyl group in the alkyl amino group and the dialkyl amino group may be a linear alkyl group or a branched alkyl group.

The alkyl group in the alkylamino group is preferably an alkyl group having 1 to 5 carbon atoms, and more preferably a methyl group, an ethyl group, or an isopropyl group.

Each alkyl group in the dialkylamino group is preferably an alkyl group having 1 to 5 carbon atoms independently, and more preferably a methyl group, an ethyl group, or an isopropyl group.

Examples of the group having a nitrogen-containing aromatic ring include a group obtained by removing one hydrogen atom from a pyridine ring (that is, a pyridyl group). The group having a nitrogen-containing aromatic ring is preferably a pyridyl group.

As the group having a nitrogen-containing aliphatic ring, a group having a piperidine ring is preferable. The group having a piperidine ring is preferably a group having a hindered amine structure, and is preferably a 1,2,2,6,6-pentamethylpiperidyl group or a 2,2,6,6-tetramethylpiperidyl group. More preferred.

-PKaH-
The pKaH of the base group is preferably 4 or more, more preferably 5 or more, still more preferably 6 or more, and 8 or more, from the viewpoint of image retention, printing resistance, and ablation inhibitory property. The above is particularly preferable. The pKaH of the base group means the pKa of the acid conjugated to the base group.

The upper limit of pKaH of the base group is not limited, but is preferably 12 or less, more preferably 11 or less, and particularly preferably 10 or less.

In the present disclosure, pKaH is calculated using ACD / pKa DB ver 8.07 of ACD / Labs software Ver 8.0 for Microsoft windows manufactured by Advanced Chemistry Development.

-LogP-
The ClogP of the structural unit B is preferably -1 to 10, more preferably 1 to 5, and 2 to 4 from the viewpoints of developability, image retention, print resistance, and ablation suppression. Is particularly preferable.

As for the method and software used for the calculation of ClogP, known ones can be used, but unless otherwise specified, the ClogP program incorporated in ChemBioDrow Ultra 12.0 of Cambridge Soft Co., Ltd. is used in this disclosure.

Further, in the calculation of ClogP of the structural unit B, the connection site (for example, * in the following structural unit UB-1) of the target structural unit (preferably the monomer unit) is replaced with a hydrogen atom for calculation.
For example, when calculating the ClogP value of the following structural unit UB-1, the ClogP value is calculated after converting the following structural unit UB-1 into a structure represented by the following UB'-1.

-Structure-
The structure of the structural unit B is not limited as long as it contains a base group. The structural unit B preferably has a structural unit represented by the following formula B1, the following formula B2, or the following formula B3 from the viewpoint of resolution, image area retention, printing resistance, and ablation inhibitory property. It is more preferable that the structural unit is represented by the following formula B1.

In formula B1, R ¹ represents a hydrogen atom or a methyl group, X ¹ represents a single bond, an ester bond or an amide bond, L ¹ represents a single bond or a divalent linking group, and Base represents a base group. Atoms contained in L ¹ and Base may form a ring, and * independently represents a bonding site with another structure.
In formula B2, Y ¹ and Y ² independently represent -O- or -NR-, R represents a hydrogen atom or an alkyl group, A ¹ represents a trivalent linking group, and L ² is a single bond. Alternatively, it represents a divalent linking group, Base represents a base group, and A ¹ or L ² may be bonded to an atom contained in Base to form a ring, and * indicates an independent structure with another structure. Represents the binding site of.
In formula B3, Y ³ and Y ⁴ independently represent -O- or -NR-, R represents a hydrogen atom or an alkyl group, and L ³ and L ⁴ independently represent a single bond or divalent, respectively. Representing a linking group, Base represents a base group, and at least one of L ³ and L ⁴ may be bonded to an atom contained in Base to form a ring, and L ³ and L ⁴ may be bonded to each other to form a ring. May be formed, and each independently represents a binding site with another structure.

A specific embodiment of the structural unit represented by the formula B1 will be described below.

In the formula B1, X ¹ represents a single bond, an ester bond or an amide bond, and is preferably an ester bond or an amide bond, and more preferably an ester bond.

In the formula B1, L ¹ represents a single bond or a divalent linking group, and is preferably a divalent hydrocarbon group which may have a single bond, a urea bond or an ether bond, and is preferably a single bond or a divalent hydrocarbon group. It is more preferably a hydrocarbon group of, and particularly preferably a single bond or divalent aliphatic saturated hydrocarbon group.
In the formula B1, when L ¹ represents a divalent hydrocarbon group, the number of carbon atoms of L ¹ is preferably 1 or more, more preferably 2 to 10, and particularly preferably 2 to 8. preferable.

In the formula B1, Base represents a base group, preferably a dialkylamino group or a group having a nitrogen-containing aliphatic ring, more preferably a group having a nitrogen-containing aliphatic ring, and a group having a piperidine ring. Is particularly preferable. The dialkylamino group, the group having a nitrogen-containing aliphatic ring, and the group having a piperidine ring are the dialkylamino group, the group having a nitrogen-containing aliphatic ring, and the group having a piperidin ring described in the above-mentioned "base group" section. Is synonymous with, and the preferred embodiment is also the same.
In the formula B1, the preferable numerical range of pKaH of the base group represented by Base is the same as the numerical range described in the above section “pKaH”.

In the formula B1, L ¹ and the atom contained in Base may be bonded to form a ring. As the ring to be formed, a tetramethylpiperidine ring or a pentamethylpiperidine ring is preferably mentioned.

Next, a specific embodiment of the structural unit represented by the formula B2 will be described below.

In formula B2, Y ¹ and Y ² preferably independently represent -O- or -NH-, respectively.
In the formula B2, when at least one of Y ¹ and Y ² represents −NR−, R is preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and more preferably a hydrogen atom or a methyl group. , A hydrogen atom is particularly preferable.

In the formula B2, A ¹ represents a trivalent linking group is preferably a trivalent hydrocarbon group, more preferably a trivalent aliphatic saturated hydrocarbon group.
In the formula B2, the number of carbon atoms of ^{A 1} is preferably 1 or more, more preferably 1 to 10, and particularly preferably from 3 to 10.

In the formula B2, L ² represents a single bond or a divalent linking group, preferably a single bond or a divalent hydrocarbon group, and preferably a single bond or a divalent aliphatic saturated hydrocarbon group.
In the formula B2, when L ² represents a divalent hydrocarbon group, the number of carbon atoms of L ² is preferably 1 or more, more preferably 1 to 10, and particularly preferably 3 to 10. preferable.

In the formula B2, Base represents a base group, preferably a dialkylamino group or a group having a nitrogen-containing aliphatic ring, more preferably a group having a nitrogen-containing aliphatic ring, and a group having a piperidine ring. Is particularly preferable. The dialkylamino group, the group having a nitrogen-containing aliphatic ring, and the group having a piperidine ring are the dialkylamino group, the group having a nitrogen-containing aliphatic ring, and the nitrogen-containing aliphatic ring described in the above-mentioned "base group" section. It is synonymous with a group having a group and a group having a piperidine ring, and the same applies to preferred embodiments.
In the formula B2, the preferable numerical range of pKaH of the base group represented by Base is the same as the numerical range described in the above section “pKaH”.

In the formula B2, may be bonded to form a ring with the atoms contained in the ^{A 1} or ^{L 2} and Base. As the ring to be formed, a tetramethylpiperidine ring or a pentamethylpiperidine ring is preferably mentioned.

In formula B2, * independently constitutes an ester bond or amide bond containing Y ¹ or Y ² by binding to a bond represented by -C (= O)-in another structure, or It is preferable to form a urethane bond or a urea bond containing Y ¹ or Y ² by binding to a bond represented by -C (= O) NH- in another structure, and -C (in another structure). = O) It is more preferable to form a urethane bond or a urea bond containing Y ¹ or Y ² by binding to the bond represented by NH−.

Further, in the formula B2, it is preferable that the molecular chain composed of Y ¹ , A ¹ , and Y ² is contained in the main chain of the binder polymer B.

Next, a preferred embodiment of the structural unit represented by the formula B3 will be described below.

In formula B3, Y ³ and Y ⁴ preferably independently represent -O- or -NH-, respectively.
In formula B3, when Y ³ , Y ⁴ , or both Y ³ and Y ⁴ represent -NR-, R is preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and is preferably a hydrogen atom or a methyl group. Is more preferable, and a hydrogen atom is particularly preferable.

In formula B3, L ³ and L ⁴ independently represent a single bond or a divalent linking group, preferably a single bond or a divalent hydrocarbon group, and a single bond or a divalent aliphatic saturated hydrocarbon group. More preferably.
In the formula B3, when L ³ or L ⁴ represents a divalent hydrocarbon group, the number of carbon atoms of the above L ³ or L ⁴ is preferably 1 or more, more preferably 1 to 10 and 2 It is particularly preferably 10 to 10.

In the formula B3, Base represents a base group, preferably a dialkylamino group or a group having a nitrogen-containing aliphatic ring, more preferably a group having a nitrogen-containing aliphatic ring, and a group having a piperidine ring. Is particularly preferable. The dialkylamino group, the group having a nitrogen-containing aliphatic ring, and the group having a piperidine ring are the dialkylamino group, the group having a nitrogen-containing aliphatic ring, and the nitrogen-containing aliphatic ring described in the above "base group" section. It is synonymous with a group having a group and a group having a piperidine ring, and the same applies to preferred embodiments.
In the formula B3, the preferable numerical range of pKaH of the base group represented by Base is the same as the numerical range described in the above section “pKaH”.

In the formula B3, at least one of L ³ and L ⁴ and an atom contained in Base may be bonded to form a ring, or L ³ and L ⁴ may be bonded to form a ring. As the ring to be formed, a tetramethylpiperidine ring or a pentamethylpiperidine ring is preferably mentioned.

In the formula B3, * each independently, -C in other structures (= O) - configuring an ester bond or an amide bond including Y ³ or Y ⁴ by binding to bond represented by, or -C in other structures (= O) is preferable to configure a urethane bond or a urea bond containing Y ³ or Y ⁴ by binding to bond represented by NH-, -C in other structures ( = O) is more preferable to construct a urethane bond or a urea bond containing Y ³ or Y ⁴ by binding to bond represented by NH-.

Further, in the formula ^{B3, Y 3, L 3,} Base, L 4, and the molecular chain composed of ^{Y 4,} is preferably contained in the main chain of the binder polymer B.

Next, preferred embodiments of the structural unit represented by the formula B1, the structural unit represented by the formula B2, and the structural unit represented by the formula B2 will be described.

The structural unit represented by the formula B1 is preferably the structural unit represented by the following formula b1.

In formula b1, R ² represents a hydrogen atom or a methyl group, X ² represents an -O- or -NR-, R represents a hydrogen atom or an alkyl group, and of L ⁵ , R ³ and R ⁴ . At least two may be bonded to form a ring, L ⁵ represents a single bond or a divalent hydrocarbon group having 1 or more carbon atoms, and R ³ and R ⁴ each independently have 1 or more carbon atoms. It represents a monovalent hydrocarbon group, and * represents a bond site with another structure independently.

In the formula b1, when X ² represents −NR−, R is preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, more preferably a hydrogen atom or a methyl group, and is a hydrogen atom. Is particularly preferable.
In the formula b1, L ⁵ is a hydrocarbon group of a single bond or a urea bond or a carbon atoms which may have ether bond at least one divalent is preferred, more preferably a single bond or a divalent hydrocarbon group, a single It is particularly preferably a bonded or divalent aliphatic saturated hydrocarbon group.
In the formula b1, the number of carbon atoms of ^{L 5} represents preferably from 2 to 10, particularly preferably 2 to 8.
In formula b1, at least two of L ⁵ , R ³ and R ⁴ may be combined to form a ring, preferably forming a piperidine ring. As the piperidine ring formed, a tetramethylpiperidine ring or a pentamethylpiperidine ring is preferably mentioned.
In formula b1, R ³ and R ⁴ are each independently preferably an aliphatic saturated hydrocarbon group having 1 or more carbon atoms.
In the formula b1, the carbon number of R ³ and R ⁴ is preferably 1 to 10.

The structural unit represented by the formula B2 is preferably the structural unit represented by the following formula b2.

In formula b2, Y ⁵ and Y ⁶ independently represent -O- or -NH-, A ² represents a trivalent hydrocarbon group having 1 or more carbon atoms, and L ⁶ is a single bond or 1 carbon atom. Representing the above divalent hydrocarbon group, at least two of L ⁶ , R ⁵ and R ⁶ may be bonded to form a ring, and R ⁵ and R ⁶ each independently have 1 or more carbon atoms. Represents a monovalent hydrocarbon group, each of which independently combines with a bond represented by the other building block -C (= O) NH- to form a urethane bond or urea containing Y ⁵ or Y ^6. Make up a bond.

In formula b2, A ² is more preferably a trivalent aliphatic saturated hydrocarbon group having 1 or more carbon atoms.
In the formula b2, the number of carbon atoms of ^{A 2} is preferably 1 to 10, more preferably 3 to 10.
In the formula b2, L ⁶ is preferably an aliphatic saturated hydrocarbon group of a single bond or a number of one or more divalent atoms.
In the formula b2, the number of carbon atoms of ^{L 6} is preferably from 1 to 10, more preferably 3 to 10.
In formula b2, at least two of L ⁶ , R ⁵ and R ⁶ may be combined to form a ring, preferably forming a piperidine ring. As the piperidine ring formed, a tetramethylpiperidine ring or a pentamethylpiperidine ring is preferably mentioned.
In formula b2, R ⁵ and R ⁶ are preferably aliphatic saturated hydrocarbon groups having 1 or more carbon atoms, respectively. The carbon number of R ¹ and R ² is preferably 1 to 10.
Further, in the formula b2, it is preferable that the molecular chain composed of Y ⁵ , A ² and Y ⁶ is contained in the main chain of the binder polymer B.

The structural unit represented by the formula B3 is preferably the structural unit represented by the following formula b3.

In formula b3, Y ⁷ and Y ⁸ independently represent -O- or -NH-, and L ⁷ and L ⁸ independently represent a single bond or a divalent hydrocarbon group having one or more carbon atoms. , R ⁷ represents a monovalent hydrocarbon group having 1 or more carbon atoms, and at least two of L ⁷ , L ⁸ and R ⁷ may be bonded to form a ring, and * is independent of each other. Combines with the bond represented by -C (= O) NH-, which is a constituent unit of, to form a urethane bond or urea bond containing Y ⁷ or Y ⁸ .

In formula b3, L ⁷ and L ⁸ are each independently preferably a single bond or a divalent aliphatic saturated hydrocarbon group having 1 or more carbon atoms.
In formula b3, when L ⁷ or L ⁸ represents a divalent hydrocarbon group having 1 or more carbon atoms, the carbon number of L ⁷ or L ⁸ is preferably 1 to 10 and is preferably 2 to 10. Is more preferable.
In formula b3, R ⁷ is preferably a monovalent aliphatic saturated hydrocarbon group having 1 or more carbon atoms.
In the formula b3, the carbon number of R ⁷ is preferably 1 to 10.
In formula b3, at least two of L ⁷ , L ⁸ and R ⁷ may be combined to form a ring, preferably forming a piperidine ring. As the piperidine ring formed, a tetramethylpiperidine ring or a pentamethylpiperidine ring is preferably mentioned.
In formula b3, it is preferable that the molecular chain composed of Y ⁷ , L ⁷ , L ⁸ and Y ⁸ is contained in the main chain of the binder polymer B.

A specific example of the structural unit B is shown below. However, the structural unit B is not limited to the following structural units.

The structural unit B in the binder polymer B may be one type alone or two or more types.

The content of the structural unit B in the binder polymer B is 5% by mass to 70% by mass with respect to the total mass of the binder polymer B from the viewpoints of developability, image retention, printing resistance, and ablation suppressing property. It is more preferable, it is more preferably 10% by mass to 60% by mass, further preferably 15% by mass to 60% by mass, and particularly preferably 25% by mass to 60% by mass.

Examples of the method of introducing the structural unit B into the binder polymer B include a method of synthesizing the binder polymer B using a monomer having a base group as a raw material. Examples of the monomer include pentamethylpiperidylmethacrylate, 2- (dimethylamino) ethyl methacrylate, 2- (diethylamino) ethyl methacrylate, 2- (diisopropylamino) ethyl methacrylate, 4-vinylpyridine, and 2-vinylpyridine. , 2- (3- (2-pyridinyl) ureido) ethyl methacrylate, 2- (3- (3-pyridinyl) ureido) ethyl methacrylate, 2- (3- (4-pyridinyl) ureido) ethyl methacrylate, tetramethylpiperidyl methacrylate , 11-Methylamide-3,6,9-trioxaundecanylamine, 2- (3- (4- (dimethylamino) phenyl) ureido) ethyl methacrylate, and 4-hydroxy-1- (2-hydroxyethyl) Included are -2,2,6,6-tetramethylpiperidin.

(Other building blocks)
The binder polymer B preferably has another structural unit in addition to the structural unit having the above base group (constituent unit B). However, the other structural units in the binder polymer B are structural units that do not correspond to the structural unit B. As the other structural unit, the other structural unit described in the above section “Binder polymer A” can be applied, and the same applies to the preferred embodiment.
Further, the binder polymer B may have a structural unit having an acid group, but preferably does not have a structural unit having an acid group.
Examples of the acid group include an acid group having a pKa of 9 or less described in the above section “Binder polymer A”. Examples of the acid group having a pKa of more than 9 include a sulfonamide group (-SO _2- NH- or -SO _2- NH ₂ ) and a phenolic hydroxyl group.
The content of the structural unit having an acid group is preferably 10% by mass or less, preferably 5% by mass or less, and preferably 1% by mass or less, based on the total mass of the binder polymer B. , 0% by mass is preferable.

(Base value)
The base value of the binder polymer B is preferably 0.5 meq / g to 4.5 meq / g, preferably 1.2 meq / g to 3. from the viewpoint of image retention, printing resistance, and ablation inhibitory property. It is more preferably 2 meq / g, further preferably 1.4 meq / g to 3 meq / g, particularly preferably 1.5 meq / g to 2 meq / g, and 1.5 meq / g to 1. Most preferably, it is 8 meq / g. In the present disclosure, the base value is measured by the perchloric acid method specified by JIS K 2501: 2003.

(Weight average molecular weight)
The weight average molecular weight (Mw) of the binder polymer B is preferably more than 5,000 and less than 200,000, and more than 10,000 and less than 100,000 from the viewpoint of developability and print resistance. Is more preferable, and 12,000 to 50,000 is particularly preferable.

[Molecular weight ratio]
The mass ratio Mw _B / Mw _A of the weight average molecular weight Mw _B of the binder polymer B to the weight average molecular weight Mw _A of the binder polymer _A is preferably 1/3 to 3/1 from the viewpoint of ablation inhibitory property. It is more preferably 1/2 to 2/1, particularly preferably 1 / 1.5 to 1.5 / 1, and most preferably 1 / 1.2 to 1.2 / 1.

[Base group / Acid group]
For substances amount _{N A} of the acid groups having a pKa of 9 or less in the binder polymer A, the ratio _N B / _{N A} (i.e., molar ratio) of the amount of substance _{N B} of base groups in the binder polymer B, developability, image portion holding From the viewpoint of property, printing resistance, and ablation inhibitory property, it is preferably 1/6 to 6/1, more preferably 1/3 to 3/1, and 1/2 to 2/1. More preferably, it is particularly preferably 1 / 1.5 to 1.5 / 1, and most preferably 1 / 1.2 to 1.2 / 1.

[Base value / acid value]
The mass ratio V _B / V _A of the base value V _B of the binder polymer B to the acid value V _A of the binder polymer _A is preferably 1/6 to 6/1 from the viewpoint of ablation inhibitory property. It is more preferably 3 to 3/1, further preferably 1/2 to 2/1, particularly preferably 1 / 1.5 to 1.5 / 1, and 1 / 1.2 to 1 / 1.2 to 1.5 / 1. Most preferably 1.2 / 1.

[Contents of Binder Polymer A and Binder Polymer B]
The total content of the binder polymer A and the binder polymer B is 10% by mass or more with respect to the total mass of all the binder polymers in the image recording layer.

In the present disclosure, the term "total binder polymer" means not only two kinds of binder polymer A and binder polymer B, but all binder polymers including binder polymer A and binder polymer B. For example, when the image recording layer further contains, in addition to the binder polymer A and the binder polymer B, other binder polymers described below, the term "total binder polymer" refers to the binder polymer A, the binder polymer B, and others. Includes binder polymers.

The total content of the binder polymer A and the binder polymer B is preferably 20% by mass or more with respect to the total mass of all the binder polymers in the image recording layer from the viewpoint of developability and ablation inhibitory property. Further, the total content of the binder polymer A and the binder polymer B is 50% by mass or more with respect to the total mass of all the binder polymers in the image recording layer from the viewpoint of developability, printing resistance, and ablation suppressing property. It is more preferably 75% by mass or more, further preferably 90% by mass or more, particularly preferably 95% by mass or more, and most preferably 100% by mass.

The total content of the binder polymer A and the binder polymer B is preferably 10% by mass to 99% by mass, preferably 20% by mass or more, based on the total mass of the image recording layer from the viewpoint of ablation suppression property. It is more preferably 95% by mass, and particularly preferably 30% by mass to 90% by mass.

The contents of the binder polymer A and the binder polymer B may be appropriately set within a range in which the total contents of the binder polymer A and the binder polymer B satisfy the above range.
From the viewpoint of ablation inhibitory property, the content of the binder polymer A is preferably 5% by mass to 60% by mass, more preferably 30% by mass to 50% by mass, based on the total mass of the image recording layer. preferable.
The content of the binder polymer B is preferably 5% by mass to 60% by mass, and more preferably 30% by mass to 50% by mass, based on the total mass of the image recording layer from the viewpoint of ablation inhibitory property. preferable.

To the content _{M A} of the binder polymer A, the mass ratio _M B / _{M A} content _{M B} of the binder polymer B, and in view of the ablation inhibitory, preferably 1 / 6-6 / 1, 1 / It is more preferably 3 to 3/1, further preferably 1/2 to 2/1, particularly preferably 1 / 1.5 to 1.5 / 1, and 1 / 1.2 to 1 / 1.2 to 1.5 / 1. Most preferably 1.2 / 1.

[Infrared absorber]
The image recording layer in the present disclosure contains an infrared absorber.

The infrared absorber is not particularly limited as long as it is a dye that absorbs infrared light and generates heat, and various dyes known as infrared absorbers can be used.
As the infrared absorber that can be used in the present disclosure, commercially available dyes and known infrared absorbers described in the literature (for example, "Dye Handbook" edited by the Society of Synthetic Organic Chemistry, published in 1970) can be used. Specific examples thereof include dyes such as azo dyes, metal complex salt azo dyes, pyrazolone azo dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinoneimine dyes, methine dyes, and cyanine dyes. In the present disclosure, from the viewpoint of being suitable for using a laser that emits infrared light or near-infrared light, among the above dyes, a dye that absorbs at least infrared light or near-infrared light is preferable, and a cyanine dye is more preferable. ..

Examples of the dye that absorbs at least the infrared light or the near-infrared light include JP-A-58-125246, JP-A-59-84356, JP-A-59-202829, and JP-A-60-78787. Cyanine dyes described in JP-A-58-173696, JP-A-58-181690, JP-A-58-194595, etc. 58-112793, JP-A-58-224793, JP-A-59-48187, JP-A-59-73996, JP-A-60-52940, JP-A-60-63744, etc. Examples thereof include naphthoquinone dyes, squarylium dyes described in JP-A-58-112792, and cyanine dyes described in British Patent No. 434,875.
Further, as the dye, the near-infrared absorption sensitizer described in US Pat. No. 5,156,938 is also preferably used. Further, the substituted arylbenzo (thio) pyrylium salt described in US Pat. No. 3,881,924 is described in JP-A-57-142645 (US Pat. No. 4,327,169). , Japanese Patent Application Laid-Open No. 58-181051, Japanese Patent Application Laid-Open No. 58-220143, Japanese Patent Application Laid-Open No. 59-41363, Japanese Patent Application Laid-Open No. 59-84248, Japanese Patent Application Laid-Open No. 59-84249. Pyrylium-based compounds described in Japanese Patent Application Laid-Open No. 59-146603 and Japanese Patent Application Laid-Open No. 59-146601, cyanine dyes described in JP-A-59-216146, US Pat. , 283,475. Pyrylium salt, Pyrylium compound described in Japanese Patent Publication No. 5-13514, and Japanese Patent Publication No. 5-9702, and Epolight III manufactured by Eporin Co., Ltd. as a commercial product. -178, Epolight III-130, and Epolight III-125 are particularly preferably used.
Further, as another example particularly preferable as the dye, the near-infrared absorbing dye described as the formula (I) and the formula (II) in the US Pat. No. 4,756,993 can be mentioned.

Among the above dyes, particularly preferable ones include cyanine dyes, phthalocyanine dyes, oxonor dyes, squarylium dyes, pyrylium salts, thiopyrylium dyes, and nickel thiolate complexes. Further, the cyanine dye represented by the following formula (a) is most preferable because it is excellent in stability and economy when used for the image recording layer in the present disclosure.

Wherein (a), ^{X 1} represents a represents a hydrogen atom, a halogen atom, a diarylamino group ^{_{(-NPh 2), X 2 -L}} 1, or a group shown below. X ² represents an oxygen atom or a sulfur atom. L ¹ represents a hydrocarbon group having 1 to 12 carbon atoms, an aromatic ring having a hetero atom, or a hydrocarbon group having 1 to 12 carbon atoms containing a hetero atom. The hetero atom represents N, S, O, a halogen atom, or Se.

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

In formula (a), R ²¹ and R ²² each independently represent a hydrocarbon group having 1 to 12 carbon atoms. From the viewpoint of storage stability of the positive lithographic printing plate original plate, R ²¹ and R ²² are preferably hydrocarbon groups having two or more carbon atoms, and further, R ²¹ and R ²² are bonded to each other and have a 5-membered ring. Alternatively, it is particularly preferable to form a 6-membered ring.

In the formula (a), Ar ¹ and Ar ² each independently represent an aromatic hydrocarbon group which may have a substituent. Preferred aromatic hydrocarbon groups include a benzene ring and a naphthalene ring. In addition, preferred substituents include a hydrocarbon group having 12 or less carbon atoms, a halogen atom, and an alkoxy group having 12 or less carbon atoms.

In formula (a), Y ¹¹ and Y ¹² independently represent a sulfur atom or a dialkylmethylene group having 12 or less carbon atoms.

In the formula (a), R ²³ and R ²⁴ each independently represent a hydrocarbon group having 20 or less carbon atoms which may have a substituent. Preferred substituents include an alkoxy group having 12 or less carbon atoms, a carboxyl group, and a sulfo group.

In formula (a), R ²⁵ , R ²⁶ , R ²⁷ and R ²⁸ each independently represent a hydrogen atom or a hydrocarbon group having 12 or less carbon atoms. From the viewpoint of availability of raw materials, a hydrogen atom is preferable.

In formula (a), Za ⁻ represents a counter anion. However, if the cyanine dye represented by the formula (a) has an anionic substituent in its structure and charge neutralization is not required, Za ⁻ is not required. Preferred Za ⁻ is a halide ion, a perchlorate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, or a sulfonic acid ion from the viewpoint of storage stability of the positive flat plate printing plate original plate, and particularly preferably a perchlorate ion. It is an ion, a hexafluorophosphate ion, or an aryl sulfonate ion.

Specific examples of the cyanine dye represented by the formula (a) that can be preferably used include paragraphs 0017 to 0019 of JP-A-2001-1333969 and paragraphs 0012 to paragraph 0038 of JP-A-2002-40638. Cyanine dyes described in paragraphs 0012 to 0023 of Kai 2002-23360 can be mentioned.

The cyanine dye A shown below is particularly preferable as the infrared absorber contained in the image recording layer.

The infrared absorber contained in the image recording layer may be one kind alone or two or more kinds.

The content of the infrared absorber is preferably 0.01% by mass to 50% by mass, more preferably 0.1% by mass to 30% by mass, based on the total mass of the image recording layer. It is particularly preferably 0% by mass to 30% by mass. When the content is 0.01% by mass or more, the sensitivity becomes high, and when the content is 50% by mass or less, the uniformity of the layer is good and the durability of the layer is excellent.

[Other binder polymers]
The image recording layer in the present disclosure may further contain other binder polymers.
The other binder polymer is a resin that does not correspond to the above-mentioned specific binder polymer.
The image recording layer in the present disclosure is composed of a group consisting of a phenol resin, a styrene-acrylonitrile copolymer, an acrylic resin, an acetal resin, and a resin having a urea bond, a urethane bond, or an amide bond in the main chain as another binder polymer. It is preferable to further contain at least one selected.
The other binder polymer is preferably an alkali-soluble resin, more preferably a weak alkali-soluble resin.

(Phenolic resin)
The phenolic resin is preferably a phenolic resin having a weight average molecular weight of more than 2,000. A phenolic resin having a weight average molecular weight of more than 2,000 is a structural unit formed of phenol or a substituted phenol compound (hereinafter, phenol and the substituted phenol compound are collectively referred to as "phenol compound") as a structural unit. It is a phenolic resin containing, preferably a novolak resin. The novolak resin is preferably used in the lithographic printing plate original plate because it causes strong hydrogen bonding in the unexposed portion and a part of the hydrogen bonding is easily released in the exposed portion.

The novolak resin is obtained, for example, by a condensation reaction between a phenol compound and an aldehyde compound.

Examples of the phenol compound include phenol, isopropylphenol, t-butylphenol, t-amylphenol, hexylphenol, cyclohexylphenol, 3-methyl-4-chloro-6-t-butylphenol, isopropylcresol, t-butylcresol, and Included is t-amilkresol. Preferably, it is t-butylphenol or t-butylcresol.

Examples of the aldehyde compound include aliphatic and aromatic aldehydes such as formaldehyde, acetaldehyde, acrolein and crotonaldehyde. Preferably, it is formaldehyde or acetaldehyde.

More specifically, the novolak resin in the present disclosure includes, for example, a shrunk polymer of phenol and formaldehyde (phenolformaldehyde resin), a shrunk polymer of m-cresol and formaldehyde (m-cresol formaldehyde resin), p. -Complex polymer of cresol and formaldehyde (p-cresol formaldehyde resin), contractile polymer of m- / p-mixed cresol and formaldehyde (m- / p-mixed cresol formaldehyde resin), and phenol and cresol (m- , P-, or m- / p-mixed formaldehyde) and formaldehyde (phenol / cresol (either m-, p-, or m- / p-mixed) mixed formaldehyde resin) Can be mentioned.
Further, as the novolak resin, as described in US Pat. No. 4,123,279, an alkyl group having 3 to 8 carbon atoms such as t-butylphenol formaldehyde resin and octylphenol formaldehyde resin can be used. Examples thereof include a condensed polymer of phenol and formaldehyde having as a substituent.
Among the above novolak resins, particularly preferable ones include phenol formaldehyde resin and phenol / cresol mixed formaldehyde resin.

The weight average molecular weight of the phenolic resin is preferably more than 2,000 and 50,000 or less, more preferably 2,500 to 20,000, and particularly preferably 3,000 to 10,000. .. The degree of dispersion (weight average molecular weight / number average molecular weight) is preferably 1.1 to 10.
The above number average molecular weight is a polystyrene-equivalent number average molecular weight measured by gel permeation chromatography (GPC) when tetrahydrofuran (THF) is used as a solvent.

(Acetal resin)
Examples of the acetal resin include polymer compounds containing a structural unit represented by the following formula EV-1 and the following formula EV-2.

In formula EV-1 or formula EV-2, L represents a divalent linking group, x is 0 or 1, and R ¹ represents an aromatic or heteroaromatic ring group having at least one hydroxy group. R ² and R ³ are independently linear or branched which may have a hydrogen atom, a halogen atom and a substituent, or a cyclic alkyl group and a linear or branched which may have a substituent. Alternatively, it represents a cyclic alkenyl group, an aromatic ring which may have a substituent, or a heteroaromatic ring which may have a substituent.

In the formula EV-1, R ¹ represents an aromatic ring or a heteroaromatic ring having at least one hydroxy group, and the hydroxy group may have an ortho, meta, or para position with respect to the binding site with L. Good.
Preferred examples of the aromatic ring include a phenyl group, a benzyl group, a tolyl group, an o-, m-, a p-xylyl group, a naphthyl group, an anthrasenyl group, and a phenanthrenyl group.
Preferred examples of the heteroaromatic ring include a frill group, a pyridyl group, a pyrimidyl group, a pyrazoyl group, and a thiophenyl group.
The aromatic ring or heteroaromatic ring may have a substituent other than the hydroxyl group. Substituents other than hydroxyl groups include alkyl groups (eg, methyl and ethyl groups), alkoxy groups (eg, methoxy and ethoxy groups), aryloxy groups, thioalkyl groups, thioaryl groups, mercapto groups and azo groups (eg, azo groups). For example, azoalkyl group and azophenyl group), thioalkyl group, amino group, ethenyl group, alkenyl group, alkynyl group, cycloalkyl group, aryl group, heteroaryl group, and heterolipocyclic group can be mentioned.
R ¹ is preferably a hydroxyphenyl group or a hydroxynaphthyl group having a hydroxy group, and more preferably a hydroxyphenyl group.
Examples of the hydroxyphenyl group include 2-, 3-, and 4-hydroxyphenyl groups.
Examples of the hydroxynaphthyl group include 2,3-, 2,4-, or 2,5-dihydroxynaphthyl group, 1,2,3-trihydroxynaphthyl group, and hydroxynaphthyl group.
The hydroxyphenyl group or hydroxynaphthyl group may have a substituent, and preferred substituents include an alkoxy group such as a methoxy group and an ethoxy group.

In the formula EV-1, L represents a divalent linking group, which is an alkylene group, an arylene group, a heteroarylene group, −O−, −C (= O) −, −C (= O) O−, −C ( = O) -NH-, -NH-C (= O)-, -NH-C (= O) -O-, -OC (= O) -NH-, -NH-C (= O)- NH-, -NH-C (= S) -NH-, -S (= O)-, -S (= O) _2- , -CH = N-, -NH-NH-, or a combination thereof It is preferable to represent the group to be represented.
The alkylene group, arylene group, or heteroarylene group may have a substituent, and the substituents include an alkyl group, a hydroxy group, an amino group, a monoalkylamino group, a dialkylamino group, an alkoxy group, and a substituent. , Phosphonic acid group or a salt thereof.
L is an alkylene group, an arylene group, or, more preferably heteroarylene _{group, -CH 2 -, - CH 2} -CH 2 -, - CH 2 -CH 2 -CH 2 -, or, phenylene group It is more preferable to have.

In the formula EV-2, R ² and R ³ may independently have a hydrogen atom, a halogen atom, a linear or branched alkyl group which may have a substituent, or a cyclic alkyl group and a substituent. Represents a linear, branched, or cyclic alkenyl group, an aromatic ring that may have a substituent, or a heteroaromatic ring that may have a substituent.
The alkyl groups include methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, chloromethyl group, trichloromethyl group, isopropyl group, isobutyl group, isopentyl group and neopentyl group. , 1-methoxybutyl group, isohexyl group, cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, and methylcyclohexyl group.
Examples of the alkenyl group include ethenyl group, n-propenyl group, n-butenyl group, n-pentenyl group, n-hexenyl group, isopropenyl group, isobutenyl group, isopentenyl group, neopentenyl group, 1-methylbutenyl group and isohexenyl. Examples include a group, a cyclopentenyl group, a cyclohexenyl group, and a methylcyclohexenyl group.
Examples of the halogen atom include a chlorine atom.
Preferred examples of the aromatic ring include aryl groups such as a phenyl group, a benzyl group, a tolyl group, o-, m-, p-xysilyl group, a naphthyl group, an anthracenyl group, and a phenanthrenyl group.
Examples of the heteroaromatic ring include a frill group, a pyridyl group, a pyrimidyl group, a pyrazoyl group, a thiophenyl group and the like.
R ² and R ³ each independently preferably represent a hydrogen atom, a chlorine atom or a methyl group, and more preferably represent a hydrogen atom.

Examples of the substituent in the alkyl group, alkenyl group, aromatic ring or heteroaromatic ring include an alkoxy group such as a methoxy group and an ethoxy group, a thioalkyl group, and a mercapto group.
The aromatic ring or heteroaromatic ring may have an azo group such as an aryloxy group, a thioaryl group, an azoalkyl group and an azoaryl group, or an amino group as a substituent.

The content of the structural unit represented by the formula EV-1 (however, converted as a monomer unit) is preferably 10 mol% or more, preferably 10 mol% to 55 mol%, based on the total amount of the monomer units in the polymer compound. Is more preferable, 15 mol% to 45 mol% is further preferable, and 20 mol% to 35 mol% is particularly preferable.
The content of the structural unit represented by the formula EV-2 (however, converted as a monomer unit) is preferably 15 mol% or more, preferably 15 mol% to 60 mol%, based on the total amount of the monomer units in the polymer compound. Is more preferable, 20 mol% to 50 mol% is further preferable, and 25 mol% to 45 mol% is particularly preferable.

Further, the total content of the structural unit represented by the formula EV-1 and the structural unit represented by the formula EV-2 (however, converted as a monomer unit) is the total amount of the monomer units in the polymer compound. On the other hand, 50 mol% to 90 mol% is preferable, 60 mol% to 80 mol% is more preferable, and 65 mol% to 75 mol% is further preferable.

The weight average molecular weight of the acetal resin is preferably 5,000 or more, more preferably 10,000 to 500,000, and even more preferably 10,000 to 300,000.

The other binder polymer contained in the image recording layer may be one kind alone or two or more kinds.

The content of the other binder polymer may be appropriately set according to the ratio (mass%) of the total content of the binder polymer A and the binder polymer B to the total mass of all the binder polymers in the image recording layer. That is, when the image recording layer contains another binder polymer, the content of the other binder polymer is 90% by mass or less and 80% by mass or less with respect to the total mass of all the binder polymers in the image recording layer. It is preferably 50% by mass or less, more preferably 25% by mass or less, particularly preferably 10% by mass or less, and most preferably 5% by mass or less. When the image recording layer contains another binder polymer, the lower limit of the content of the other binder polymer may be appropriately set in a range exceeding 0% by mass.

[Acid generator]
The image recording layer in the present disclosure preferably contains an acid generator from the viewpoint of improving the sensitivity of the obtained planographic printing plate original plate.
In the present disclosure, the acid generator refers to a compound that generates an acid by light or heat, and refers to a compound that generates an acid by decomposing it by irradiation with infrared rays or heating at 100 ° C. or higher. 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 this acid generator increases the permeability of the developer into the exposed image recording layer in the lithographic printing plate original plate, and further improves the solubility of the image recording layer in the alkaline aqueous solution.
Examples of the acid generator preferably used in the image recording layer in the present disclosure include the acid generators described in paragraphs 0116 to 0130 of International Publication No. 2016/047392.
Above all, from the viewpoint of sensitivity and stability, it is preferable to use an onium salt compound as the acid generator. Hereinafter, the onium salt compound will be described.
Examples of the onium salt compound that can be preferably used in the present disclosure include infrared exposure and a compound known as a compound that is decomposed by heat energy generated from an infrared absorber by exposure to generate an acid. Examples of onium salt compounds suitable for the present disclosure include known thermal polymerization initiators and those having an onium salt structure described below, which has a bond having a small bond dissociation energy, from the viewpoint of sensitivity.
Examples of the onium salt preferably used in the present disclosure include known diazonium salts, iodonium salts, sulfonium salts, ammonium salts, pyridinium salts, azinium salts and the like, among which triarylsulfonium or diaryliodonium sulfonates. , _{^{carboxylate, BF 4 -, PF 6 -}} , ClO 4 - and the like are preferable.
Examples of the onium salt that can be used as the acid generator in the present disclosure include onium salts represented by the following formulas (III) to (V).

In the above formula (III), Ar ¹¹ and Ar ¹² each independently represent an aryl group having 20 or less carbon atoms which may have a substituent. When the aryl group has a substituent, preferable substituents include a halogen atom, a nitro group, an alkyl group having 12 or less carbon atoms, an alkoxy group having 12 or less carbon atoms, and an aryloxy group having 12 or less carbon atoms. .. Z ^11- is a pair selected from the group consisting of sulfonate ions having a fluorine atom such as halide ion, perchlorate ion, tetrafluoroborate ion, hexafluorophosphate ion, sulfonic acid ion, and perfluoroalkyl sulfonic acid ion. Represents an ion, preferably a perchlorate ion, a hexafluorophosphate ion, an aryl sulfonic acid ion, and a perfluoroalkyl sulfonic acid.
In the above formula (IV), Ar ²¹ represents an aryl group having 1 to 20 carbon atoms which may have a substituent. Preferred substituents include a halogen atom, a nitro group, an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aryloxy group having 1 to 12 carbon atoms, and an alkylamino group having 1 to 12 carbon atoms. Examples thereof include a dialkylamino group having 2 to 12 carbon atoms, an arylamino group having 6 to 12 carbon atoms, and a diarylamino group (the carbon atoms of the two aryl groups are independently 6 to 12). Z ^21- represents a counterion synonymous with Z ^11- .
In the above formula (V), R ³¹ , R ^32, and R ³³ each independently represent a hydrocarbon group having 1 to 20 carbon atoms which may have a substituent. Preferred substituents include halogen atoms, nitro groups, alkyl groups having 1 to 12 carbon atoms, alkoxy groups having 1 to 12 carbon atoms, and aryloxy groups having 1 to 12 carbon atoms. Z ^31- represents a counterion synonymous with Z ^11- .

Specific examples of the onium salt that can be suitably used in the image recording layer in the present disclosure are the same as the compounds described in paragraphs 0121 to 0124 of International Publication No. 2016/047392.

Further, as another example of the compound represented by the above formulas (III) to (V), the compound described as an example of the radical polymerization initiator in paragraphs 0036 to 0045 of JP-A-2008-195018 is used. , Can be suitably used as the acid generator according to the present disclosure.

More preferable examples of the acid generators that can be used in the present disclosure include the following compounds PAG-1, compound PAG-2, compound PAG-3, compound PAG-4, and compound PAG-5.

The acid generator contained in the image recording layer may be used alone or in combination of two or more.

When the image recording layer contains an acid generator, the content of the acid generator is preferably 0.01% by mass to 50% by mass, preferably 0.1% by mass to 50% by mass, based on the total mass of the image recording layer. 40% by mass is more preferable, and 0.5% by mass to 30% by mass is further preferable. When the content is in the above range, the sensitivity, which is the effect of adding the acid generator, is improved, and the generation of the residual film in the non-image area is suppressed.

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

The acid growth agents that can be used are the same as those described in paragraphs 0133 to 0135 of WO 2016/047392.

The acid proliferation agent contained in the image recording layer may be one kind alone or two or more kinds.

When the image recording layer contains an acid growth agent, the content of the acid growth agent is preferably 0.01% by mass to 20% by mass, preferably 0.01% by mass or more, based on the total mass of the image recording layer. It is more preferably 10% by mass, and particularly preferably 0.1% by mass to 5% by mass. When the content of the acid growth agent is within the above range, the effect of adding the acid growth agent is sufficiently obtained, the sensitivity is improved, and the decrease in the film strength of the image portion is suppressed.

[Other additives]
The image recording layer in the present disclosure may contain a development accelerator, a surfactant, a baking agent, a coloring agent, a plasticizer, a waxing agent, and the like as other additives.

-Development accelerator-
An acid anhydride compound, a phenol compound, or an organic acid compound may be added to the image recording layer in the present disclosure for the purpose of improving the sensitivity.
The acid anhydride compound is preferably cyclic acid anhydride, and specifically, the cyclic acid anhydride is phthalic anhydride, tetrahydrophthalic anhydride, or hexahydrophthalic anhydride described in US Pat. No. 4,115,128. Phthalic anhydride, 3,6-endooxytetrahydrophthalic anhydride, tetrachlorophthalic anhydride, maleic anhydride, chloromaleic anhydride, α-phenylphthalic anhydride, succinic anhydride, pyromellitic anhydride and the like can be used. Examples of the acyclic acid anhydride include acetic anhydride.
Examples of the phenol compound include bisphenol A, 2,2'-bishydroxysulfone, p-nitrophenol, p-ethoxyphenol, 2,4,4'-trihydroxybenzophenone, 2,3,4-trihydroxybenzophenone, 4-. Hydroxybenzophenone, 4,4', 4 "-trihydroxytriphenylmethane, 4,4', 3", 4 "-tetrahydroxy-3,5,3', 5'-tetramethyltriphenylmethane and the like can be mentioned. ..
Examples of the organic acid compound are described in JP-A-60-888942, JP-A-2-96755 and the like, and specifically, p-toluenesulfonic acid, dodecylbenzenesulfonic acid, p-toluenesulfinic acid. , Ethyl sulfate, phenylphosphonic acid, phenylphosphinic acid, phenyl phosphate, diphenyl phosphate, benzoic acid, isophthalic acid, adipic acid, p-toluic acid, 3,4-dimethoxybenzoic acid, phthalic acid, terephthalic acid, 4- Cyclohexene-1,2-dicarboxylic acid, erucic acid, lauric acid, n-undecanoic acid, ascorbic acid and the like can be mentioned. The ratio of the above acid anhydride compound, phenol compound and organic acid compound to the total mass of the image recording layer is preferably 0.05% by mass to 20% by mass, more preferably 0.1% by mass to 15% by mass. 0.1% by mass to 10% by mass is particularly preferable.

-Surfactant-
The image recording layer in the present disclosure is described in JP-A-62-251740 and JP-A-3-208514 in order to improve the coatability and to expand the stability of processing under development conditions. Nonionic surfactants such as those described in JP-A-59-121044, and amphoteric surfactants as described in JP-A-4-13149, JP-A-62-170950, JP-A. A fluorine-containing monomer copolymer as described in Japanese Patent Application Laid-Open No. 11-288093 and Japanese Patent Application Laid-Open No. 2003-57820 can be added.
Specific examples of the nonionic surfactant include sorbitan tristearate, sorbitan monopalmitate, sorbitan triolate, stearic acid monoglyceride, polyoxyethylene nonylphenyl ether and the like.
Specific examples of amphoteric activators include alkyldi (aminoethyl) glycine, alkylpolyaminoethylglycine hydrochloride, 2-alkyl-N-carboxyethyl-N-hydroxyethyl imidazolinium betaine, and N-tetradecyl-N, N-. A betaine type (for example, trade name "Amogen K": manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) can be mentioned.
The ratio of the surfactant to the total mass of the image recording layer is preferably 0.01% by mass to 15% by mass, more preferably 0.01% by mass to 5% by mass, and 0.05% by mass to 2.0% by mass. % Is more preferable.

-Burning agent / coloring agent-
To the image recording layer in the present disclosure, a baking agent for obtaining a visible image immediately after heating by exposure, or a dye or pigment as an image colorant can be added.
Examples of the burnout agent and the colorant are described in detail in paragraphs 0122 to 0123 of JP-A-2009-229917, and the compounds described herein can also be applied in the present disclosure.
The dye is preferably added at a ratio of 0.01 to 10% by mass, and more preferably 0.1% by mass to 3% by mass, based on the total mass of the image recording layer.

-Plasticizer-
A plasticizer may be added to the image recording layer in the present disclosure in order to impart flexibility of the coating film and the like. For example, butyl phthalyl, polyethylene glycol, tributyl citrate, diethyl phthalate, dibutyl phthalate, dihexyl phthalate, dioctyl phthalate, tricresyl phosphate, tributyl phosphate, trioctyl phosphate, tetrahydrofurfuryl oleate, acrylic acid or methacrylic acid. Oligomers and polymers of the above are used.
The plasticizer is preferably added at a ratio of 0.5% by mass to 10% by mass, more preferably 1.0% by mass to 5% by mass, based on the total mass of the image recording layer. ..

-Waxing agent-
A compound that lowers the coefficient of static friction on the surface may be added to the image recording layer in the present disclosure for the purpose of imparting resistance to scratches. Specifically, as described in US Pat. Nos. 6,117,913, JP-A-2003-149799, JP-A-2003-302750, or JP-A-2004-12770. Examples thereof include compounds having an ester of a long-chain alkylcarboxylic acid.
The addition amount is preferably 0.1% by mass to 10% by mass, more preferably 0.5% by mass to 5% by mass, based on the total mass of the image recording layer.

[Formation of image recording layer]
Examples of the method for forming the image recording layer include a method using a coating liquid containing each of the above components and a solvent. As a specific example of the method for forming the image recording layer, for example, there is a method of forming the image recording layer by applying the coating liquid on the support and drying it if necessary. The method for preparing the coating liquid is not limited. The coating liquid can be prepared, for example, by mixing the above components and a solvent.
From the viewpoint of the solubility of the specific binder polymer, the solvent used for preparing the coating solution preferably contains an acid compound such as acetic acid.
Examples of the drying method include natural drying, air drying, and heat drying.

[Image recording layer with a two-layer structure]
The image recording layer in the present disclosure preferably includes a lower layer and an upper layer. When the image recording layer includes a lower layer and an upper layer, the positive lithographic printing plate original plate according to the present disclosure has a support and an image recording layer including the lower layer and the upper layer on the support in this order.

When the image recording layer includes a lower layer and an upper layer, the binder polymer A, the binder polymer B, and the infrared absorber may be contained in at least one of the lower layer and the upper layer, respectively. From the viewpoint of ablation inhibitory property, it is preferable that at least one of the lower layer and the upper layer contains the binder polymer A, the binder polymer B, and the infrared absorber. Further, from the viewpoint of ablation inhibitory property, it is also preferable that one of the lower layer and the upper layer contains the binder polymer A, and the other of the lower layer and the upper layer contains the binder polymer B.

Among the above, from the viewpoint of ablation inhibitory property, at least one of the lower layer and the upper layer preferably contains the binder polymer A, the binder polymer B, and the infrared absorber, and at least the upper layer contains the binder polymer A, the binder polymer B, and the infrared absorber. , The binder polymer A, the binder polymer B, and the infrared absorber are more preferable.

Hereinafter, preferred embodiments of the lower layer and the upper layer will be described.

(Underlayer)
The lower layer may be a layer containing the specific binder polymer and the infrared absorber, but is preferably a layer not containing the specific binder polymer.
The lower layer is preferably an infrared-sensitive positive recording layer whose solubility in an alkaline aqueous solution is improved by heat.
The mechanism by which the solubility in the alkaline aqueous solution is improved by the heat in the lower layer is not particularly limited, and any one containing a binder resin and improving the solubility in the heated region can be used. Examples of the heat used for image formation include heat generated when the lower layer containing an infrared absorber is exposed.
The lower layer whose solubility in an alkaline aqueous solution is improved by heat includes, for example, a layer containing an alkali-soluble resin having a hydrogen-bonding ability such as novolak and urethane, a water-insoluble and alkali-soluble resin, and a compound having a dissolution inhibitory action. Layers and the like are preferred.

Further, by further adding an infrared absorber to the lower layer, the heat generated in the lower layer can also be used for image formation. The composition of the lower layer containing the infrared absorber includes, for example, a layer containing an infrared absorber, a water-insoluble / alkali-soluble resin, and a compound having a dissolution inhibitory effect, an infrared absorber, a water-insoluble / alkali-soluble resin, and an acid generator. A layer containing the above is preferable.

-Water-insoluble and alkali-soluble resin-
The lower layer in the present disclosure preferably contains a water-insoluble and alkali-soluble resin. By containing the water-insoluble and alkali-soluble resin, an interaction is formed between the infrared absorber and the polar group of the water-insoluble and alkali-soluble resin, and a positive photosensitive layer is formed.
The general water-insoluble and alkali-soluble resin will be described in detail below. Among them, for example, polyamide resin, epoxy resin, polyacetal resin, acrylic resin, methacrylic resin, polystyrene resin, novolak type phenol resin and the like are preferably mentioned. be able to.
The water-insoluble and alkali-soluble resin that can be used in the present disclosure is not particularly limited as long as it has the property of dissolving when in contact with an alkaline developing solution, but the main chain and / or side chain in the polymer is acidic. It is preferably a homopolymer containing a group, a copolymer thereof, or a mixture thereof.
The water-insoluble and alkali-soluble resin having such an acidic group preferably has a functional group such as a phenolic hydroxyl group, a carboxy group, a sulfonic acid group, a phosphoric acid group, a sulfonamide group and an active imide group. Therefore, such a resin can be suitably produced by copolymerizing a monomer mixture containing one or more ethylenically unsaturated monomers having the above functional groups. As the ethylenically unsaturated monomer having the above functional group, in addition to acrylic acid and methacrylic acid, a compound represented by the following formula and a mixture thereof can be preferably exemplified. In the following formula, R ⁴⁰ represents a hydrogen atom or a methyl group.

The water-insoluble and alkali-soluble resin that can be used in the present disclosure is preferably a polymer compound obtained by copolymerizing another polymerizable monomer in addition to the above-mentioned polymerizable monomer. In this case, the copolymerization ratio is 10 mol of a monomer that imparts alkali solubility, such as a monomer having a functional group such as a phenolic hydroxyl group, a carboxy group, a sulfonic acid group, a phosphoric acid group, a sulfonamide group, or an active imide group. % Or more is preferable, and those containing 20 mol% or more are more preferable. When the copolymerization component of the monomer that imparts alkali solubility is 10 mol% or more, alkali solubility is sufficiently obtained, and the developability is excellent.

Examples of other polymerizable monomers that can be used include the compounds listed below.
Alkyl acrylates or alkyl methacrylates such as methyl acrylate, ethyl acrylate, propyl acrylate, benzyl acrylate, methyl methacrylate, ethyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, etc. Acrylic acid ester compounds having an aliphatic hydroxyl group such as 2-hydroxyethyl acrylate or 2-hydroxyethyl methacrylate, and methacrylic acid ester compounds. Acrylamide or methacrylamide such as acrylamide, methacrylamide, N-methylacrylamide, N-ethylacrylamide, N-phenylacrylamide, etc. Vinyl ester compounds such as vinyl acetate, vinyl chloroacetate, vinyl butyrate, and vinyl benzoate. Styrene compounds such as styrene, α-methylstyrene, methylstyrene, and chloromethylstyrene. Other nitrogen atom-containing monomers such as N-vinylpyrrolidone, N-vinylpyridine, acrylonitrile, and methacrylonitrile. N-methylmaleimide, N-ethylmaleimide, N-propylmaleimide, N-butylmaleimide, N-phenylmaleimide, N-2-methylphenylmaleimide, N-2,6-diethylphenylmaleimide, N-2-chlorophenylmaleimide, Maleimide compounds such as N-cyclohexylmaleimide, N-laurylmaleimide, and N-hydroxyphenylmaleimide.
Among the ethylenically unsaturated monomers, preferably used are (meth) acrylic acid ester compounds, (meth) acrylamide compounds, maleimide compounds, and (meth) acrylonitrile.

Further, as the alkali-soluble resin, the novolak resin mentioned as another binder polymer mentioned as an optional component of the image recording layer according to the present disclosure is also preferably mentioned.
It is also possible to use the above water-insoluble and alkali-soluble resin for the image recording layer in the present disclosure.

Further, other resins can be used in combination in the lower layer in the present disclosure as long as the effects according to the present disclosure are not impaired. Since the lower layer itself is required to exhibit alkali solubility, especially in the non-imaging region, it is necessary to select a resin that does not impair this property. From this point of view, examples of the resin that can be used in combination include water-insoluble and alkali-soluble resins. The general water-insoluble and alkali-soluble resin will be described in detail below. Among them, for example, polyamide resin, epoxy resin, polyacetal resin, acrylic resin, methacrylic resin, polystyrene resin, novolak type phenol resin and the like are preferably mentioned. be able to.
The amount to be mixed is preferably 50% by mass or less with respect to the water-insoluble and alkali-soluble resin.

The water-insoluble and alkali-soluble resin preferably has a weight average molecular weight of 2,000 or more and a number average molecular weight of 500 or more, a weight average molecular weight of 5,000 to 300,000, and a number average molecular weight of 800 to 800. More preferably, it is 250,000. The dispersity (weight average molecular weight / number average molecular weight) of the alkali-soluble resin is preferably 1.1 to 10.
The alkali-soluble resin in the lower layer according to the present disclosure may be used alone or in combination of two or more.
The content of the alkali-soluble resin in the total solid content of the lower layer in the present disclosure is preferably 2.0% by mass to 99.5% by mass and 10.0% by mass to 99.% by mass with respect to the total mass of the lower layer. It is more preferably 0% by mass, and even more preferably 20.0% by mass to 90.0% by mass. When the amount of the alkali-soluble resin added is 2.0% by mass or more, the durability of the image recording layer (photosensitive layer) is excellent, and when it is 99.5% by mass or less, both sensitivity and durability are improved. Excellent.

-Infrared absorber-
The lower layer may contain an infrared absorber.
The infrared absorber is not particularly limited as long as it is a dye that absorbs infrared light and generates heat, and the infrared absorber used in the image recording layer in the present disclosure described above can be used in the same manner.
A particularly preferable infrared absorber is a cyanine dye represented by the above formula (a).

By containing an infrared absorber in the lower layer, the exposure sensitivity is improved.
The amount of the infrared absorber added in the lower layer is preferably 0.01% by mass to 50% by mass, more preferably 0.1% by mass to 30% by mass, based on the total mass of the lower layer. It is particularly preferably 0.0% by mass to 10% by mass. When the addition amount is 0.01% by mass or more, the sensitivity is improved, and when it is 50% by mass or less, the uniformity of the layer is good and the durability of the layer is excellent.

-Other ingredients-
The lower layer may contain an acid generator, an acid growth agent, a development accelerator, a surfactant, a baking agent / colorant, a plasticizer, a wax agent and the like.
As these components, the respective components used in the image recording layer in the present disclosure described above can be used in the same manner, and the preferred embodiment is also the same.

(Upper layer)
The upper layer preferably contains a specific binder polymer and an infrared absorber from the viewpoint of ablation inhibitory property and printing resistance. Further, the upper layer may contain other components contained in the lower layer in addition to the above-mentioned components.

(Method of forming lower and upper layers)
The lower layer and the upper layer are preferably formed by separating the two layers.
As a method for forming the two layers separately, for example, a method utilizing the difference in solvent solubility between the component contained in the lower layer and the component contained in the upper layer, or a method in which the upper layer is applied and then the solvent is rapidly applied. Examples include a method of drying and removing the solvent. It is preferable to use the latter method in combination because the separation between layers can be performed more satisfactorily.
Hereinafter, these methods will be described in detail, but the method of applying the two layers separately is not limited thereto.

As a method of utilizing the difference in solvent solubility between the component contained in the lower layer and the component contained in the upper layer, when the coating solution for forming the upper layer is applied, the component contained in the lower layer is used as the solvent of the coating solution. Examples thereof include a method using an insoluble solvent. As a result, even if two layers are applied, each layer can be clearly separated into a coating film. For example, as the lower layer component, a solvent insoluble in a solvent (for example, methyl ethyl ketone and 1-methoxy-2-propanol) that dissolves the specific binder polymer contained in the upper layer component is selected, and a solvent that dissolves the lower layer component is selected. After forming the lower layer by applying the coating liquid for forming the lower layer prepared using the above on the support and drying it, the upper layer component containing the specific binder polymer is dissolved with methyl ethyl ketone or 1-methoxy-2-propanol. By applying the prepared coating liquid for forming the upper layer on the lower layer and then drying it, it becomes possible to form two layers.

Next, as a method of drying the solvent extremely quickly after applying the second layer (upper layer), high-pressure air is blown from a slit nozzle installed almost at right angles to the traveling direction of the web, or a heating medium such as steam. Can be achieved by giving thermal energy as conduction heat from the lower surface of the web from a roll (heating roll) supplied inside, or by combining them.

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

[Undercoat layer]
The positive lithographic printing plate original plate according to the present disclosure may have an undercoat layer between the support and the image recording layer (or the lower layer when the image recording layer includes a lower layer and an upper layer), if necessary.
As the undercoat layer component, various organic compounds are used, for example, phosphonic acid having an amino group such as carboxymethyl cellulose and dextrin, organic phosphonic acid, organic phosphoric acid, organic phosphinic acid, amino acid, and having a hydroxy group. Amino acid hydrochloride and the like are preferably mentioned. Further, these undercoat layer components may be used alone or in combination of two or more. Details of the compound used for the undercoat layer and a method for forming the undercoat layer are described in paragraphs 0171 to 0172 of JP2009-175195A, and these descriptions also apply to the present disclosure.
The coverage of the undercoat layer ^is preferably from ^{2mg / m 2 ~200mg / m 2} , and more preferably ^{5mg / m 2 ~100mg / m 2} . When the coating amount is in the above range, sufficient printing durability can be obtained.

[Back coat layer]
A back coat layer is provided on the back surface of the support of the planographic printing plate original plate according to the present disclosure, if necessary. The backcoat layer is composed of an organic polymer compound described in JP-A-5-45885 and a metal oxide obtained by hydrolyzing and polycondensing an organic or inorganic metal compound described in JP-A-6-35174. A coating layer is preferably used. Among these coating layers, silicon alkoxy compounds such as Si (OCH ₃ ) ₄ , Si (OC ₂ H ₅ ) ₄ , Si (OC ₃ H ₇ ) ₄ , and Si (OC ₄ H ₉ ) ₄ are available at low cost. The metal oxide coating layer obtained from the coating layer is particularly preferable because it has an excellent developer resistance.

<How to make a lithographic printing plate>
The method for producing the lithographic printing plate according to the present disclosure is not limited as long as it is the method using the positive lithographic printing plate original plate according to the present disclosure. The method for producing a lithographic printing plate according to the present disclosure includes a step of image-exposing the positive lithographic printing plate original plate (hereinafter, also referred to as "exposure step") and a developing solution for the exposed positive lithographic printing plate original plate. It is preferable to include the step of developing using the above (hereinafter, also referred to as “development step”) in this order, the step of image-exposing the positive lithographic printing plate original plate and the exposed positive lithographic printing. It is more preferable to include the step of developing the plate original plate with a developing solution having a pH of 10.0 or less in this order. In the method for producing a lithographic printing plate according to the present disclosure, the occurrence of ablation can be suppressed by using the positive lithographic printing plate original plate according to the present disclosure.
Hereinafter, each step of the production method according to the present disclosure will be described in detail.

[Exposure process]
The method for producing a lithographic printing plate according to the present disclosure preferably includes a step of image-exposing the positive lithographic printing plate original plate according to the present disclosure.
As the light source of the active light used for the image exposure of the lithographic printing plate original plate according to the present disclosure, a light source having an emission wavelength in the near infrared to infrared region is preferable, and a solid-state laser and a semiconductor laser are more preferable. Above all, in the present disclosure, it is particularly preferable that the image is exposed by a solid-state laser or a semiconductor laser that emits infrared rays having a wavelength of 750 nm to 1,400 nm.
The laser output is preferably 100 mW or more, and it is preferable to use a multi-beam laser device in order to shorten the exposure time. The exposure time per pixel is preferably 20 μsec or less.
Energy irradiated on the planographic printing plate precursor ^is preferably ^{10mJ / cm 2 ~300mJ / cm 2} . Within the above range, the solubility of the image recording layer in an alkaline aqueous solution is sufficiently improved, laser ablation can be suppressed, and image damage can be prevented.

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

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

[Development process]
The method for producing a lithographic printing plate according to the present disclosure preferably includes a step of developing the exposed positive lithographic printing plate original plate with a developing solution.

The pH of the developing solution is not limited and can be appropriately set according to the composition of the image recording layer and the like. The pH of the developing solution is preferably 10.0 or less from the viewpoint of developability.

The developer is preferably an aqueous solution.

Further, in the method for producing a lithographic printing plate according to the present disclosure, development may be carried out using a developing solution having a pH of more than 10.0. For example, it is also possible to develop using a known developer such as the developer described in paragraphs 0270 to 0292 of JP-A-2003-1956.

Further, in order to improve the developability, the developer may contain a surfactant.
As the surfactant used in the developer, any of anionic, nonionic, cationic and amphoteric surfactants can be used, but as described above, anionic and nonionic surfactants can be used. Agents are preferred.
As the anionic, nonionic, cationic and amphoteric surfactants used in the developing solution in the present disclosure, those described in paragraphs 0128 to 0131 of JP2013-134341A can be used.

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

The developer used in the developing step is preferably a developer having a pH of 10.0 or less, more preferably a developer having a pH of 8.0 to 10.0, and a developer having a pH of 9.00 to 9.9. Is particularly preferable.
In a developer having a relatively low pH as described above, the pH is lowered due to, for example, dissolution of CO _{2 in} the atmosphere, as compared with a developer having a high pH of around 12, for example, which is conventionally used. Easy to be suppressed. That is, it can be said that the low pH makes the developer excellent in stability during use or storage.
In a low pH developer, the decrease in pH in the developer is suppressed as described above, so that the decrease in developability and the generation of development residue are suppressed.
Further, in order to keep the pH of the low pH developer at the initial value, it is also preferable to use the developer as a buffer solution. The buffer solution is particularly preferably a carbonate buffer system.
In the present disclosure, the carbonate buffer system refers to a buffer solution containing carbonate ions and hydrogen carbonate ions as a buffer.
In order to make carbonate ion and hydrogen carbonate ion present in the developing solution, carbonate and hydrogen carbonate may be added to the developing solution, or carbonate may be added by adjusting the pH after adding the carbonate or hydrogen carbonate. Ions and bicarbonate ions may be generated. The carbonate and the hydrogen carbonate are not particularly limited, but are preferably alkali metal salts. Examples of the alkali metal include lithium, sodium and potassium, and sodium is particularly preferable. These may be used alone or in combination of two or more.

The total amount of carbonate and hydrogen carbonate is preferably 0.3% by mass to 20% by mass, more preferably 0.5% by mass to 10% by mass, and 1% by mass to 5% by mass with respect to the total mass of the developing solution. % Is particularly preferable. If the total amount is 0.3% by mass or more, the developability and processing capacity do not decrease, and if it is 20% by mass or less, it becomes difficult to form a precipitate or crystals, and further, during waste liquid treatment of the developing solution and neutralization. It becomes difficult to gel and does not interfere with the waste liquid treatment.

Further, for the purpose of finely adjusting the alkali concentration and assisting the dissolution of the non-image recording layer, another alkaline agent, for example, an organic alkaline agent may be used in combination. Examples of organic alkaline agents include monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, triisopropylamine, n-butylamine, monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, and the like. Examples thereof include diisopropanolamine, ethyleneimine, ethylenediamine, pyridine and tetramethylammonium hydroxide. These other alkaline agents may be used alone or in combination of two or more.
In addition to the above, the developer may contain a wetting agent, a preservative, a chelating compound, an antifoaming agent, an organic acid, an organic solvent, an inorganic acid, an inorganic salt and the like. However, it is preferable not to add the water-soluble polymer compound because the plate surface becomes sticky especially when the developer is fatigued.

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

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

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

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

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

Examples of the organic solvent include aliphatic hydrocarbon compounds (hexane, heptane, "isopar E, H, G" (manufactured by Esso Chemical Co., Ltd.), gasoline, kerosene, etc.), aromatic hydrocarbon compounds (toluene, etc.). Xylene, etc.), or halogenated hydrocarbons (methylene dichloride, ethylene dichloride, tricrene, monochlorobenzene, etc.), and polar solvents can be mentioned.

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

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

Examples of the inorganic acid and salt include phosphoric acid, metaphosphoric acid, ammonium primary phosphate, ammonium dibasic phosphate, sodium primary phosphate, sodium dibasic phosphate, potassium monophosphate, potassium dibasic phosphate, and the like. Examples thereof include sodium tripolyphosphate, potassium pyrophosphate, sodium hexametaphosphate, magnesium nitrate, sodium nitrate, potassium nitrate, ammonium nitrate, sodium sulfate, potassium sulfate, ammonium sulfate, sodium sulfite, ammonium sulfite, sodium hydrogen sulfate, nickel sulfate and the like. The content of the inorganic salt is preferably 0.01% by mass to 0.5% by mass with respect to the total mass of the developing solution.

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

The developing step can be preferably carried out by an automatic processing machine provided with a rubbing member. Examples of the automatic processing machine include the automatic processing machine and the cylinder described in Japanese Patent Application Laid-Open No. 2-220061 and Japanese Patent Application Laid-Open No. 60-59351, which perform a rubbing process while transporting a planographic printing plate original plate after image exposure. The automatic processing machines described in US Pat. Nos. 5,148,746, 5,568,768, and 229,719, UK, which rub the original planographic printing plate after image exposure set above while rotating the cylinder, are listed. Be done. Among them, an automatic processing machine using a rotating brush roll as a rubbing member is particularly preferable.

The rotary brush roll used in the present disclosure can be appropriately selected in consideration of the resistance to scratching of the image portion, the strength of the waist in the support of the planographic printing plate original plate, and the like. As the rotary brush roll, a known one formed by planting a brush material on a plastic or metal roll can be used. For example, as described in JP-A-58-159533, JP-A-3-100554, and Japanese Patent Application Laid-Open No. 62-167253, a metal or plastic in which brush materials are implanted in a row. A brush roll in which the groove-shaped material of No. 1 is wound radially around a plastic or metal roll as a core without gaps can be used.
As the brush material, plastic fibers (for example, polyester type such as polyethylene terephthalate and polybutylene terephthalate, polyamide type such as nylon 6.6 and nylon 6.10, polyacrylic type such as polyacrylonitrile and poly (meth) alkyl acrylate) , Polyester, polystyrene and other polyolefin-based synthetic fibers) can be used. For example, fibers having a hair diameter of 20 μm to 400 μm and a hair length of 5 mm to 30 mm can be preferably used.
The outer diameter of the rotary brush roll is preferably 30 mm to 200 mm, and the peripheral speed of the tip of the brush rubbing the plate surface is preferably 0.1 m / sec to 5 m / sec. It is preferable to use a plurality of rotary brush rolls.

The rotation direction of the rotary brush roll may be the same direction or the opposite direction to the transport direction of the flat plate printing plate original plate, but when two or more rotary brush rolls are used, at least one is used. It is preferable that the rotating brush rolls of the above rotate in the same direction and at least one rotating brush roll rotates in the opposite direction. As a result, the removal of the image recording layer in the non-image portion becomes more reliable. Further, it is also effective to swing the rotating brush roll in the direction of the rotation axis of the brush roll.

After the developing step, it is preferable to provide a continuous or discontinuous drying step. Drying is performed by hot air, infrared rays, far infrared rays, or the like.
As an automatic processing machine preferably used in the method for producing a lithographic printing plate according to the present disclosure, an apparatus having a developing unit and a drying unit is used, and the lithographic printing plate original plate is developed and gummed in a developing tank. After that, it is dried in a drying section to obtain a lithographic printing plate.

Further, for the purpose of improving printing durability and the like, the printed plate after development can be heated under very strong conditions. The heating temperature is preferably in the range of 200 ° C. to 500 ° C. If the temperature is low, a sufficient image enhancement effect cannot be obtained, and if it is too high, problems such as deterioration of the support and thermal decomposition of the image portion may occur.
The lithographic printing plate thus obtained is applied to an offset printing machine and is suitably used for printing a large number of sheets.

Hereinafter, the present disclosure will be described in detail with reference to Examples, but the present disclosure is not limited thereto. In this embodiment, "%" and "part" mean "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 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.

The following abbreviations used in the examples represent the following compounds, respectively. However, in Tables 1 to 5 below, the following abbreviations represent structural units formed by the following compounds, respectively.
-"A1-1": 11-acrylamide undecanoic acid (synthetic product)
-"A1-2": 6-acrylamide hexanoic acid (manufactured by Sigma-Aldrich)
-"A1-3": 2-methacryloyloxyethyl succinic acid (manufactured by Kyoeisha Chemical Co., Ltd.)
-"A1-4": 2-acryloyloxyethyl hexahydrophthalic acid (manufactured by Kyoeisha Chemical Co., Ltd.)
-"A1-5": ω-carboxy-polycaprolactone (n≈2) monoacrylate (manufactured by Toagosei Co., Ltd.)
・ "A1-6": Methacrylic acid (manufactured by Tokyo Chemical Industry Co., Ltd.)
・ "A1-7": Acrylic acid (manufactured by Tokyo Chemical Industry Co., Ltd.)
・ "A1-8": 4-Vinyl benzoic acid (manufactured by Tokyo Chemical Industry Co., Ltd.)
-"A1-9": 2-acryloyloxyethyl acid phosphate (manufactured by Kyoeisha Chemical Co., Ltd.)
-"A1-10": 2-acrylamide-2-methylpropanesulfonic acid (manufactured by Tokyo Chemical Industry Co., Ltd.)
-"A1-11": Dimethylpropionic acid (manufactured by Tokyo Chemical Industry Co., Ltd.)
-"B1-1": Pentamethylpiperidylmethacrylate (manufactured by Hitachi Chemical Co., Ltd.)
-"B1-2": 2- (dimethylamino) ethyl methacrylate (manufactured by Sigma-Aldrich)
-"B1-3": 2- (diethylamino) ethyl methacrylate (manufactured by Sigma-Aldrich)
-"B1-4": 2- (diisopropylamino) ethyl methacrylate (manufactured by Sigma-Aldrich)
-"B1-5": 4-vinylpyridine (manufactured by Tokyo Chemical Industry Co., Ltd.)
-"B1-6": 2-vinylpyridine (manufactured by Tokyo Chemical Industry Co., Ltd.)
-"B1-7": 2- (3- (2-pyridinyl) ureido) ethyl methacrylate (synthetic product)
-"B1-8": 2- (3- (3-pyridinyl) ureido) ethyl methacrylate (synthetic product)
-"B1-9": 2- (3- (4-pyridinyl) ureido) ethyl methacrylate (synthetic product)
-"B1-10": Tetramethylpiperidylmethacrylate (manufactured by Hitachi Chemical Co., Ltd.)
-"B1-13": 4-hydroxy-1- (2-hydroxyethyl) -2,2,6,6-tetramethylpiperidine (manufactured by Tokyo Chemical Industry Co., Ltd.)

The compounds represented by A1-1 to A1-11 are compounds that form a structural unit (constituent unit A) having an acid group having a pKa of 9 or less, respectively. The structural units formed by the compounds represented by the compounds A1-1 to A1-11 correspond to the structural units A1-1 to A1-11 shown in the section of "binder polymer A", respectively.
The compounds represented by B1-1 to B1-10 and B1-13 are compounds that form a structural unit (constituent unit B) having a base group, respectively. The structural units formed by the compounds represented by the compounds B1-1 to B1-10 and B1-13 are the structural units B1-1 to B1-10 and B1- shown in the section of "Binder polymer B", respectively. Corresponds to 13.

<Synthesis of A1-1>
100 g of acetonitrile and 10 g of 11-aminoundecanoic acid were placed in a three-necked flask and stirred at 5 ° C. 5 g of methacrylic acid chloride was added dropwise thereto, and 1 g of triethylamine was further added dropwise thereto. After reacting at room temperature (25 ° C.) for 1 hour, 100 g of pure water was added, the oil phase was extracted with 300 g of ethyl acetate, and then the solvent was distilled off at 40 ° C. under reduced pressure of 120 mmHg. The obtained solid was recrystallized from diisopropyl ether to obtain A1-1.

<Synthesis of B1-7>
10.0 g of Karenz MOI (manufactured by Showa Denko KK) was placed in a three-necked flask and stirred at room temperature. 5 g of 2-aminopyridine was slowly added dropwise thereto. After reacting at room temperature for 1 hour, the mixture was diluted with 100 g of hexane, and the precipitated solid was collected by filtration. The obtained solid was washed with hexane to obtain B1-7.

<Synthesis of B1-8 and B1-9>
In the synthesis of B1-7, 2-aminopyridine was synthesized in the same manner except that it was changed to the corresponding amine (3-aminopyridine or 4-aminopyridine).

<Synthesis of binder polymer A>
Polymers Q-1 to Q-24, which are binder polymers A, were synthesized by the following methods.

[Synthesis of Q-1]
1-methoxy-2-propanol: 48.0 g was placed in a three-necked flask and stirred at 75 ° C. for 30 minutes under a nitrogen stream. Next, in the above three-necked flask, A1-1: 7.44 g, methyl methacrylate (MMA, manufactured by Tokyo Chemical Industry Co., Ltd.): 1.28 g, V-601 (2,2'-azobis (2-methylpropionic acid)). A mixed solution of dimethyl, a polymerization initiator, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd .: 0.34 g and methanol: 12.0 g was added dropwise over 2 hours. After completion of the dropping, the mixture was further reacted at 75 ° C. for 2 hours, and then poured into well-stirred water: 500 g to precipitate a solid. The precipitated solid was filtered, washed with water and dried under reduced pressure to obtain polymer Q-1.

[Synthesis of Q-2 to Q-24]
Synthesis was carried out in the same manner as in Polymer Q-1, except that the compound forming the structural unit was appropriately changed.

<Synthesis of binder polymer B>
Polymers P-1 to P-24, which are binder polymers B, were synthesized by the following methods.

[Synthesis of P-1]
1-Methoxy-2-propanol: 48.0 g was placed in a three-necked flask and stirred at 75 ° C. for 30 minutes under a nitrogen stream. Next, in the above three-necked flask, methyl methacrylate (MMA, manufactured by Tokyo Chemical Industry Co., Ltd.): 1.28 g, B1-1: 6.28 g, V-601 (trade name, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) A mixture of 0.34 g and 12.0 g of methanol was added dropwise over 2 hours. After completion of the dropping, the mixture was further reacted at 75 ° C. for 2 hours, and then poured into well-stirred water: 500 g to precipitate a solid. The precipitated solid was filtered, washed with water and dried under reduced pressure to obtain polymer P-1.

[Synthesis of P-2 to P-24]
The synthesis was carried out by the same method as that of the polymer P-1, except that the compound forming the structural unit was appropriately changed.

<Examples 1-1 to 1-48 and Comparative Examples 1-1 to 1-6>
[Preparation of support]
The support was manufactured in the same manner as in paragraphs 0224 to 0297 of WO 2015/152209. This support was used in all examples and comparative examples.

[Formation of undercoat layer]
The undercoat layer coating solution 1 shown below was applied onto the support and then dried at 80 ° C. for 15 seconds to provide an undercoat layer. The coating amount after drying was 15 mg / m ² .

[Undercoat layer coating liquid 1]
-The following copolymer with a weight average molecular weight of 28,000: 0.3 parts-Methanol: 100 parts-Water: 1 part

In the above chemical formula, the parenthesized subscripts represent the content (mass%) of each structural unit. In addition, Et represents an ethyl group.

[Preparation of photosensitive resin composition]
Each component described in the following composition was mixed to prepare a photosensitive resin composition (I). The photosensitive resin composition (I) is a positive type photosensitive resin composition.

[Photosensitive resin composition (I)]
Binder polymers listed in Tables 1 to 3: Amounts listed in Tables 1 to 3 Infrared absorbers listed in Tables 1 to 3: 0.045 parts Megafuck® F-780 (DIC) Made by Co., Ltd.): 0.03 part, acetic acid: 33.0 part, methyl ethyl ketone: 8.0 part, 1-methoxy-2-propanol: 14.0 part, 1- (4-methylbenzyl) -1-phenyl 5-Benzyl-4-hydroxy-2-methoxybenzenesulfonate of piperidinium: 0.01 part

[Formation of image recording layer]
In each Example or Comparative Example, the photosensitive resin composition (I) was applied to the obtained support with an undercoat layer with a wire bar, and then dried in a drying oven at 150 ° C. for 40 seconds to specify a specific binder. The coating amount of the polymer was adjusted to 1.0 g / m ² , an image recording layer was provided, and a lithographic printing plate original plate was obtained.

The following evaluations were made using the obtained planographic printing plate original plate. The evaluation results are shown in Tables 1 to 3.

[Developability]
The obtained planographic printing plate original plate was drawn with a Trendsetter VX manufactured by Creo as an image at a beam intensity of 9 W and a drum rotation speed of 150 rpm (revolutions per minute). Then, the developer 1 having the following composition was immersed in a developing bath, and the time required for developing the non-image area was measured at a developing temperature of 30 ° C. The immersion time at which the image density of the image recording layer measured by the Macbeth densitometer became equivalent to the image density of the support was defined as the non-image area development time, and the measured values are shown in the table. If the image density of the image recording layer was not equal to the image density of the support at 30 seconds after the immersion, it was described as "development impossible". The shorter the development time of the non-image area, the better the developability.

[Developer 1: pH 9.7]
-Water: 8964 parts by mass-Sodium carbonate: 200 parts by mass-Sodium hydrogen carbonate: 100 parts by mass-Newcol B4SN (trade name, polyoxyethylene naphthyl ether sulfate, manufactured by Nippon Emulsifier Co., Ltd.): 300 parts by mass-ethylenediamine Tetraacetate tetrasodium salt: 80 parts by mass

[Image retention]
The obtained planographic printing plate original plate was immersed in a developing bath containing a developer 1 without exposure, and the image density of the image recording layer measured by a Macbeth densitometer at a developing temperature of 30 ° C. was the image before immersion. The immersion time, which was 3% lower than the image density of the recording layer, was defined as the image portion holding time. When the reduction rate of the image density was less than 3% even 80 seconds after the start of immersion, it was described as ">80". The longer the image development time, the better the image retention.

[Print resistance]
The obtained planographic printing plate original plate was drawn with a Trendsetter manufactured by Creo in a test pattern at a beam intensity of 9 W and a drum rotation speed of 150 rpm (revolutions per minute).
Then, using the PS processor LP940H manufactured by FUJIFILM Corporation, which was charged with the developer 1, the development was performed at a development temperature of 30 ° C. and a development time of the non-image development time + 2 seconds. This was continuously printed using a printing machine Lithrone manufactured by Komori Corporation. As the ink, a special ink ink manufactured by Toyo Ink Co., Ltd. containing calcium carbonate was used as a model of a low-grade material. At this time, the printing durability was evaluated by visually measuring how many sheets could be printed while maintaining a sufficient ink density. The number of sheets in Comparative Example 1-2 was set to 100, and a relative evaluation was performed based on the number of sheets.

[Ablation inhibitory]
A transparent polyethylene terephthalate film (manufactured by FUJIFILM Corporation) having a thickness of 0.1 mm was brought into close contact with the surface of the lithographic printing plate original plate, and the entire surface was exposed under the same conditions as in the evaluation of developability.
After the exposure, the polyethylene terephthalate film was removed and visually observed to observe the degree of stain on the surface. Those with no stains were evaluated as A, those with some stains as B, and those that were soiled to the extent that they could not be seen through the film through the film were evaluated as C.
It can be said that the less the stain is, the more excellent the ablation inhibitory property is, and the evaluation is preferably A or B, and more preferably A.

In each of the above tables, the following abbreviations represent building blocks formed by the following compounds, respectively.

・ "MMA": Methyl methacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.)
・ "EHMA": Ethylhexyl methacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.)
-"BnMA": Benzyl methacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.)
・ "MDI": Diphenylmethane diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd.)
-"PPG1200": Unior D-1200 (manufactured by NOF CORPORATION)
・ "MA": Methacrylamide (manufactured by Tokyo Chemical Industry Co., Ltd.)
・ "ACN": Acrylonitrile (manufactured by Tokyo Chemical Industry Co., Ltd.)

In each of the above tables, the following abbreviations represent the following compounds, respectively.

-"IR-1": The following infrared absorber IR-1
-"IR-2": The following infrared absorber IR-2
-"IR-3": The following infrared absorber IR-3

-"R-1": Novolac resin (m-cresol / p-cresol / phenol = 3/2/5 (molar ratio), Mw: 8,000, PR-55618 manufactured by Sumitomo Bakelite Co., Ltd.)
-"R-2": The following copolymer (R-2)

In the above chemical formula, the parenthesized subscripts represent the content (mass%) of each structural unit. In addition, Me represents a methyl group. In each of the above tables, the structural unit having a sulfonamide group (the structural unit on the left side) in the above chemical formula is referred to as "R-2A".

"R-3": The following copolymer (R-3) (P-6 described in JP-A-2009-045852)

In the above chemical formula, the parenthesized subscripts represent the content (mass%) of each structural unit. In each of the above tables, in the above chemical formula, the structural unit having ₁₇ groups of C ₈ F (the structural unit on the left side) is "R-3A", and the structural unit having ₂₅ groups of C ₁₂ H is "R". -3B ”and the structural unit having a carboxy group (the structural unit on the right side) are referred to as“ R-3C ”.

In each of the above tables, the values described in the columns of pKaH, pKa, ClogP, acid value, base value, and Mw (weight average molecular weight) indicate the values measured by the above method, respectively.
In each of the above tables, the value described in the column of "A + B [%]" is the ratio (mass%) of the total contents of the binder polymer A and the binder polymer B to the total mass of all the binder polymers in the image recording layer. Is shown.
In the above table, the values listed in the "NB / NA" is relative amounts of substance N _A of the acid groups having a pKa of 9 or less in the binder polymer A, the ratio of the substance quantity N _B of base groups in the binder polymer B Indicates N _B / N _A.
In each of the above tables, the unit of the value described in the columns of "acid value" and "base value" is meq / g.
In each of the above tables, "R-1A" represents a structural unit having a phenolic hydroxyl group contained in the novolak resin (R-1).

The matters described for each of the above tables are the same in Tables 4 to 5 described later.

<Examples 2-1 to 2-6 and Comparative Examples 2-1 to 2-4>
[Making a two-layer lithographic printing plate]
In each Example or Comparative Example, the following composition for forming a lower layer (II) is applied on a support similar to that in Example 1-1 with a wire bar, and then dried in a drying oven at 133 ° C. for 60 seconds. The photosensitive resin composition (I) produced in the same manner as in Example 1-1 above after the binder polymer was applied to a coating amount of 0.7 g / m ² and a lower layer was provided (details of the binder polymer are as follows. (As shown in Table 4) was applied with a wire bar to provide an upper layer. After coating, it was dried at 130 ° C. for 50 seconds to obtain a lithographic printing plate original plate having a combined coating amount of 1.0 g / m ² for the lower layer and the upper layer.

[Coating liquid composition for lower layer formation (II)]
-Polymer UP-1, compound of the following structural formula, weight average molecular weight 40,000: 3.5 parts-Megafuck F-780: 0.07 parts-Methylethyl ketone: 30.0 parts-1-methoxy-2-propanol: 15.0 parts, γ-butyrolactone: 15.0 parts, 4,4'-bishydroxyphenyl sulfone: 0.3 parts, tetrahydrophthalic acid: 0.4 parts, p-toluene sulfonic acid: 0.02 parts, 3 parts −methoxy-4-diazodiphenylamine hexafluorophosphate: 0.06 part ・ Compound in which the counter ion of ethyl violet was changed to 6-hydroxynaphthalene sulfonic acid: 0.15 part

In the above structure, the subscripts in parentheses represent the content (mol%) of each structural unit.

Using the obtained lithographic printing plate original plate having a two-layer structure, the developability, image area retention, print resistance, and ablation inhibitory property were evaluated by the same method as described above. The evaluation results are shown in Table 4.

<Example 3-1>
In Example 2-1 the lower layer forming composition (II) was changed to the following lower layer forming composition (II-B), and the photosensitive resin composition (I) was changed to the following photosensitive resin composition (I). A lithographic printing plate original plate having a two-layer structure was produced by the same method as in Example 2-1 except that it was changed to −B). Using the obtained lithographic printing plate original plate having a two-layer structure, the developability, image area retention, print resistance, and ablation inhibitory property were evaluated by the same method as described above. The evaluation results are shown in Table 5.

[Coating liquid composition for lower layer formation (II-B)]
-P-1: 0.3 parts-Polymer UP-1, compound of the above structural formula, weight average molecular weight 40,000: 3.2 parts-Megafuck F-780: 0.07 parts-Acid acid: 22.0 parts -Methylethyl ketone: 8.0 parts-1-methoxy-2-propanol: 15.0 parts-γ-butyrolactone: 15.0 parts-4,5'-bishydroxyphenyl sulfone: 0.3 parts-Tetrahydrophthalic acid: 0 .4 parts ・ p-toluenesulfonic acid: 0.02 part ・ 3-methoxy-4-diazodiphenylamine hexafluorophosphate: 0.06 part ・ Compound in which the counter ion of ethyl violet was changed to 6-hydroxynaphthalene sulfonic acid: 0 .15 copies

[Photosensitive resin composition (IB)]
・ Q-1: 0.3 part ・ Infrared absorber IR-1: 0.045 part ・ Megafuck F-780: 0.03 part ・ Methyl ethyl ketone: 41.0 part ・ 1-methoxy-2-propanol: 14. 0 part · 5-benzoyl-4-hydroxy-2-methoxybenzenesulfonate of 1- (4-methylbenzyl) -1-phenylpiperidinium: 0.01 part

<Example 3-2>
In Example 2-1 the lower layer forming composition (II) was changed to the following lower layer forming composition (II-C), and the photosensitive resin composition (I) was changed to the following photosensitive resin composition (I). A lithographic printing plate original plate having a two-layer structure was produced by the same method as in Example 2-1 except that it was changed to −C). Using the obtained lithographic printing plate original plate having a two-layer structure, the developability, image area retention, print resistance, and ablation inhibitory property were evaluated by the same method as described above. The evaluation results are shown in Table 5.

[Coating liquid composition for lower layer formation (II-C)]
-Q-1: 0.3 parts-Polymer UP-1, compound of the above structural formula, weight average molecular weight 40,000: 3.2 parts-Megafuck F-780: 0.07 parts-Methylethyl ketone: 30.0 parts・ 1-methoxy-2-propanol: 15.0 parts ・ γ-butyrolactone: 15.0 parts ・ 4,4'-bishydroxyphenyl sulfone: 0.3 parts ・ Tetrahydrophthalic acid: 0.4 parts ・ p-toluene Sulfonic acid: 0.02 part ・ 3-methoxy-4-diazodiphenylamine hexafluorophosphate: 0.06 part ・ Compound in which the pair ion of ethyl violet was changed to 6-hydroxynaphthalene sulfonic acid: 0.15 part

[Photosensitive resin composition (IC)]
・ P-1: 0.3 part ・ Infrared absorber IR-1: 0.045 part ・ Megafuck F-780: 0.03 part ・ Acetic acid: 33.0 part ・ Methyl ethyl ketone: 8.0 part ・ 1-methoxy -2-propanol: 14.0 parts · 1- (4-methylbenzyl) -1-phenylpiperidinium 5-benzoyl-4-hydroxy-2-methoxybenzenesulfonate: 0.01 parts

From the results shown in Tables 1 to 5, it can be seen that the positive lithographic printing plate original plate according to the present disclosure is excellent in ablation inhibitory property. Further, it can be seen that the positive lithographic printing plate original plate according to the present disclosure is also excellent in developability, image area retention, and printing resistance.

Claims (13)

With the support
An image recording layer on the support
Have,
The image recording layer contains a binder polymer A having a structural unit having an acid group having a pKa of 9 or less, a binder polymer B having a structural unit having a base group, and an infrared absorber.
A positive lithographic printing plate original plate in which the total content of the binder polymer A and the binder polymer B is 10% by mass or more with respect to the total mass of all the binder polymers in the image recording layer. The positive planographic printing plate original plate according to claim 1, wherein the structural unit having the base group is a structural unit represented by the following formula B1, the following formula B2, or the following formula B3.

In formula B1, R ¹ represents a hydrogen atom or a methyl group, X ¹ represents a single bond, an ester bond or an amide bond, L ¹ represents a single bond or a divalent linking group, and Base represents a base group. Atoms contained in L ¹ and Base may form a ring, and * independently represents a bonding site with another structure.
In formula B2, Y ¹ and Y ² independently represent -O- or -NR-, R represents a hydrogen atom or an alkyl group, A ¹ represents a trivalent linking group, and L ² is a single bond. Alternatively, it represents a divalent linking group, Base represents a base group, and A ¹ or L ² may be bonded to an atom contained in Base to form a ring, and * indicates an independent structure with another structure. Represents the binding site of.
In formula B3, Y ³ and Y ⁴ independently represent -O- or -NR-, R represents a hydrogen atom or an alkyl group, and L ³ and L ⁴ independently represent a single bond or divalent, respectively. Representing a linking group, Base represents a base group, and at least one of L ³ and L ⁴ may be bonded to an atom contained in Base to form a ring, and L ³ and L ⁴ may be bonded to each other to form a ring. May be formed, and each independently represents a binding site with another structure. The positive lithographic printing plate original plate according to claim 1 or 2, wherein the base group is a group having a piperidine ring. The positive lithographic printing plate according to any one of claims 1 to 3, wherein the structural unit having an acid group having a pKa of 9 or less is a structural unit represented by the following formula A1 or the following formula A2. Original version.

In formula A1, R ^1A represents a hydrogen atom or a methyl group, X ^1A represents a single bond, an ester bond or an amide bond, L ^1A represents a single bond or a divalent linking group, and Acid has a pKa of 9 or less. It represents an acid group, and * represents a binding site with another structure independently.
In formula A2, Y ^1A and Y ^2A independently represent -O- or -NR-, R represents a hydrogen atom or an alkyl group, A ^1A represents a trivalent linking group, and L ^2A is a single bond. Alternatively, it represents a divalent linking group, Acid represents an acid group having a pKa of 9 or less, and * represents a binding site with another structure independently. The positive lithographic printing plate original plate according to any one of claims 1 to 4, wherein the pKaH of the base group is 8 to 11. The positive lithographic printing plate original plate according to any one of claims 1 to 5, wherein the ClogP of the structural unit having the base group is 1 to 5. For substances amount _{N A} of the pKa of 9 or less of the acid groups in the binder polymer A, the ratio _N B / _{N A} substance quantity _{N B} of the base groups in the binder polymer B is, at 1 / 2-2 / 1 The positive type lithographic printing plate original plate according to any one of claims 1 to 6. The positive lithographic printing plate original plate according to any one of claims 1 to 7, wherein the pKa of the acid group is 3 to 6. The positive lithographic printing plate original plate according to any one of claims 1 to 8, wherein the acid group is a carboxy group. One of claims 1 to 9, wherein the total content of the binder polymer A and the binder polymer B is 50% by mass or more with respect to the total mass of all the binder polymers in the image recording layer. Positive type lithographic printing plate original plate described in. Claims 1 to 10, wherein the image recording layer includes a lower layer and an upper layer, and at least one of the lower layer and the upper layer contains the binder polymer A, the binder polymer B, and the infrared absorber. The positive flat plate printing plate original plate described in any one of the items. Claims 1 to claim that the image recording layer includes a lower layer and an upper layer, one of the lower layer and the upper layer contains the binder polymer A, and the other of the lower layer and the upper layer contains the binder polymer B. The positive type planographic printing plate original plate according to any one of 10. The step of image-exposing the positive lithographic printing plate original plate according to any one of claims 1 to 12.
A step of developing the exposed positive lithographic printing plate original plate with a developer having a pH of 10.0 or less, and
A method for producing a lithographic printing plate including the above in this order.