WO2020111050A1 - Original plate for lithographic printing plate and method for manufacturing lithographic printing plate - Google Patents

Abstract

The present invention provides an original plate for a lithographic printing plate, and a method for manufacturing a lithographic printing plate by using the original plate for a lithographic printing plate. The original plate for a lithographic printing plate has a support, a lower layer of an image recording layer, and an upper layer of the image recording layer in this order. The lower layer of the image recording layer contains a polymer A having a structural unit having an -SO2-NH- structure the pKa of which is less than 10. The upper layer of the image recording layer contains an infrared-ray absorbent and a polymer B having a structural unit having an acid group the pKa of which is less than 10. The content of the polymer B is 30 mass% or more with respect to the total mass of polymers contained in the upper layer of the image recording layer.

Description

Lithographic printing plate precursor and method of making lithographic printing plate

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

Generally, a lithographic printing plate consists of a lipophilic image area that receives ink during the printing process and a hydrophilic non-image area that receives fountain solution.
Lithographic printing utilizes the property that water and oil-based ink repel each other, making the lipophilic image part of the lithographic printing plate the ink receiving part and the hydrophilic non-image part dampening water receiving part (ink non-receiving part). ) Is a method in which a difference in ink adhesion is caused on the surface of the lithographic printing plate, the ink is applied only to the image area, and then the ink is transferred to a printing medium such as paper for printing.
Currently, in a plate making process for producing a lithographic printing plate from a lithographic printing plate precursor, image exposure is performed by a CTP (computer to plate) technique. That is, the image exposure is performed by using a laser or a laser diode by directly scanning the lithographic printing plate precursor without using a lith film.
Known lithographic printing plate precursors include those described in Patent Documents 1 to 3, for example. Further, as the conventional lithographic printing plate precursor and developer composition, for example, those described in Patent Document 4 are known.

Patent Document 1 discloses that at least two positive recording layers containing a resin and an infrared absorber and having an increased solubility in an alkaline aqueous solution by infrared laser exposure are provided on a support. Among the positive recording layers, the positive recording layer closest to the support has at least one selected from the structural unit represented by the following general formula (I) and the structural unit represented by the following general formula (II). A layer containing two or more kinds of resins containing a polymer, and at least one of the two or more kinds of resins forms a dispersed phase in the layer, and the resin forming the dispersed phase dissolves in an alkaline aqueous solution. A lithographic printing plate precursor is described which is characterized in that the speed is slower than the dissolution rate of a resin forming a matrix phase in an aqueous alkali solution.

In the general formula (I) and the general formula (II), R ¹ represents a hydrogen atom or an alkyl group. Z represents —O— or —NR ² , and R ² represents a hydrogen atom, an alkyl group, an alkenyl group, or an alkynyl group. Ar ¹ and Ar ² each independently represent an aromatic group, and at least one is a heteroaromatic group. a and b each independently represent 0 or 1.

In Patent Document 2, a structural unit represented by the following general formula (I) and a general formula (II) below are provided on a hydrophilic support having a surface roughness (Ra) of 0.45 to 0.60. There is described a lithographic printing plate precursor comprising a recording layer containing a polymer having at least one selected from the structural units described above, a phenol resin, and an infrared absorber.

In the general formula (I) and the general formula (II), R ¹ represents a hydrogen atom or an alkyl group. Z represents —O— or —NR ² , and R ² represents a hydrogen atom, an alkyl group, an alkenyl group, or an alkynyl group. Ar ¹ and Ar ² each independently represent an aromatic group, and at least one is a heteroaromatic group. a and b each independently represent 0 or 1.

Patent Document 3 has a support having a hydrophilic surface or a support provided with a hydrophilic layer, and a heat-sensitive coating containing an infrared absorber, a phenol resin, and a first polymer, and a first polymer. , A heat-sensitive positive lithographic printing plate precursor which is an alkali-soluble polymer containing a monomer unit having a structure represented by formula I or formula II below.

In the above formula I and formula II, * indicates a binding site of the monomer unit in the polymer main chain; R ¹ is hydrogen or an alkyl group; Z is oxygen or NR ² ; , 0 or 1; R ² is hydrogen or an optionally substituted alkyl, alkenyl or alkynyl group; Ar ¹ and Ar ² are aromatic groups, provided that at least Ar ¹ and Ar ² are One is an optionally substituted heteroaromatic group.

Patent Document 4 discloses (A) an alkaline agent, (B) a compound represented by the following general formula (I), a metal salt of a Group 2 element of the periodic table of the (C) element, and a (D) carboxylic acid. Alternatively, an alkaline developer composition for preparing a lithographic printing plate is described, which comprises a polymer having a salt thereof.

[In the above formula, R ¹ to R ⁴ each independently represent H, R ⁸ OH, or —(AO) _a (BO) _b R ⁹ ; AO and BO are selected from an ethyleneoxy group and a propyleneoxy group. Be done. Here, a and b represent integers from 0 to 300, but (a+b)≠0. R ⁸ represents a divalent linking group, R ⁹ represents H, CH ₃ , COR ¹⁰ , CONHR ¹¹ , and R ¹⁰ and R ¹¹ represent an alkyl group, an aryl group, an alkenyl group or an alkynyl group. R ⁵ and R ⁶ each independently represent a divalent linking group, and may be the same or different. R ⁷ can be selected from the groups defined for R ¹ to R ⁴ above, or can be the following general formula (II)

In the formula, R ³ ′ is the same as R ³ defined in formula (I), R ⁴ ′ is the same as R ⁴ defined in formula (I), and R ⁵ ′ is defined in formula (I). R ⁶ is the same as R ⁵ , R ⁶ ′ is the same as R ⁶ defined in formula (I), and R ⁷ ′ is the same as R ⁷ defined in formula (I). ) Can be selected from the substituent group. In formulas (I) and (II), n represents an integer of 0 to 20, and when n is 2 or more, R ⁷ and R ⁷ ′ can be independently selected.

Patent Document 1: Japanese Patent Application Laid-Open No. 2009-175195 Patent Document 2: Japanese Patent Application Laid-Open No. 2009-251107 Patent Document 3: International Publication No. 2007/099047 Patent Document 4: International Publication No. 2014/003134

The problem to be solved by the embodiments of the present disclosure is to provide a lithographic printing plate precursor excellent in developability and printing durability even after storage with time.
A problem to be solved by another embodiment of the present disclosure is to provide a method for producing a planographic printing plate using the planographic printing plate precursor.

Means for solving the above problems include the following aspects.
<1> A support, an image recording layer lower layer, and an image recording layer upper layer are provided in this order,
The lower layer of the image recording layer contains a polymer A having a structural unit having a —SO ₂ —NH— structure with a pKa of less than 10,
The image recording layer upper layer contains a polymer B having a structural unit having an acid group having a pKa of less than 10, and an infrared absorber,
A planographic printing plate precursor in which the content of the polymer B is 30% by mass or more based on the total mass of the polymer contained in the upper layer of the image recording layer.
<2> The lithographic printing plate precursor as described in <1>, wherein the —SO ₂ —NH— structure in the polymer A is a structure represented by any one of the following formulas 1 to 3.

In Formulas 1 to 3, Ar ₁ represents an arylene group, Ar ₂ represents an aryl group or a heteroaryl group, R ₁ represents a monovalent organic group, and * represents a bond with another structure. Represents a part.

<3> The lithographic printing plate precursor as described in <2> above, wherein the —SO ₂ —NH— structure in the polymer A is a structure represented by the formula 1.
<4> above Ar ₁ in the formula 1 is a group having a phenylene structure, said Ar ₂ is a heteroaryl group, a lithographic printing plate precursor as described in <3>.
<5> the Ar ₁ in the formula 1 is a group having a phenylene structure, wherein Ar ₂ is a furan ring, isothiazoline ring, isoxazoline ring, oxadiazoline ring, oxa triazine ring, an oxazoline ring, a pyrazine ring, a pyridazine A heteroaryl group having at least one heteroaromatic ring structure selected from the group consisting of a ring, a pyridine ring, a pyrimidine ring, a tetrazine ring, a thiadiazole ring, a thiatriazole ring, a thiazole ring, a thiophene ring and a triazine ring, The lithographic printing plate precursor as described in <3> or <4>.
<6> above Ar ₁ in the formula 1 is a group having a phenylene structure, wherein Ar ₂ is isoxazoline ring, a pyridazine ring, a pyrimidine ring, at least one selected from the group consisting of thiadiazole ring and a thiazole ring The lithographic printing plate precursor as described in any one of the above items <3> to <5>, which is a heteroaryl group having a heteroaromatic ring structure.
<7> The lithographic printing plate precursor as described in any one of the above items <1> to <6>, wherein the acid group in the polymer B is a carboxy group.
<8> The lithographic printing plate precursor as described in any one of <1> to <7>, wherein the polymer B in the lower layer of the image recording layer further has a structural unit having a basic group.
<9> The lithographic printing plate precursor as described in <8> above, wherein the basic group in the polymer B is a tertiary amino group.
<10> The lithographic printing plate precursor as described in any one of <1> to <9>, wherein the polymer A has a pKa of the —SO ₂ —NH— structure of 3.5 or more and 8.5 or less. ..
<11> The lithographic printing plate precursor as described in any one of <1> to <10>, wherein the acid group in the polymer B has a pKa of 3.0 or more and 7.0 or less.
<12> An exposure step of exposing the lithographic printing plate precursor according to any one of the above <1> to <11> to an image, and development of developing the exposed lithographic printing plate precursor with a developing solution. A method for producing a lithographic printing plate, comprising steps in this order.
<13> The method for producing a lithographic printing plate as described in <12>, wherein the developer has a pH of 10.0 or less.

According to the embodiment of the present disclosure, it is possible to provide a lithographic printing plate precursor having excellent developability and printing durability even after storage with time.
Further, according to another embodiment of the present disclosure, it is possible to provide a method for producing a lithographic printing plate using the lithographic printing plate precursor.

The details of the present disclosure will be described below. The description of the constituent elements described below may be made based on a representative embodiment of the present disclosure, but the present disclosure is not limited to such an embodiment.
In the present disclosure, “to” indicating a numerical range is used to mean that numerical values described before and after the numerical range are included as a lower limit value and an upper limit value.
In the numerical ranges described stepwise in the present disclosure, the upper limit 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 stepwise described numerical range. .. Further, in the numerical range described in the present disclosure, the upper limit value or the lower limit value of the numerical range may be replaced with the value shown in the examples.
Further, in the present disclosure, the amount of each component in the composition is the total amount of the corresponding substances present in the composition, unless a plurality of substances corresponding to each component are present in the composition. Means
In addition, in the notation of a group (atomic group) in the present disclosure, the notation that does not indicate substituted and unsubstituted includes not only those having no substituent but also those having a substituent. For example, the “alkyl group” includes not only an alkyl group having no substituent (unsubstituted alkyl group) but also an alkyl group having a substituent (substituted alkyl group).
In the present disclosure, “(meth)acryl” is a term used as a concept including both acryl and methacryl, and “(meth)acryloyl” is a term used as a concept including both acryloyl and methacryloyl. is there.
Further, in the present disclosure, with respect to the notation of the group in the compound represented by the formula, when substitution or non-substitution is not mentioned, and when the group can further have a substituent, there is no other particular limitation. As long as the group includes not only an unsubstituted group but also a group having a substituent. For example, in the formula, if “R represents an alkyl group, an aryl group or a heterocyclic group” is described, “R represents an unsubstituted alkyl group, a substituted alkyl group, an unsubstituted aryl group, a substituted aryl group, an unsubstituted group. "Represents a heterocyclic group or a substituted heterocyclic group".
In addition, the term “process” in the present disclosure is included in the term not only as an independent process but also when it cannot be clearly distinguished from other processes as long as the intended purpose of the process is achieved. Be done.
Moreover, in this indication, "mass %" and "weight%" are synonymous, and "mass part" and "weight part" are synonymous.
Furthermore, in the present disclosure, a combination of two or more preferable aspects is a more preferable aspect.
In addition, the weight average molecular weight (Mw) and the number average molecular weight (Mn) in the present disclosure are columns of TSKgel GMHxL, TSKgel G4000HxL, and TSKgel G2000HxL (both manufactured by Tosoh Corp.) unless otherwise specified. The gel permeation chromatography (GPC) analyzer was used to detect the solvent THF (tetrahydrofuran) with a differential refractometer, and the molecular weight was calculated using polystyrene as a standard substance.
In the present disclosure, the total solid content refers to the total mass of components in the composition excluding volatile components such as a solvent.
In the present disclosure, the term “lithographic printing plate precursor” includes not only the lithographic printing plate precursor but also the discarded plate precursor. In addition, the term "lithographic printing plate" includes not only a lithographic printing plate precursor prepared through an operation such as exposure and development, but also a discarding plate, if necessary. In the case of a waste original plate, the operations of exposure and development are not always necessary. The waste plate is a lithographic printing plate precursor to be attached to a plate cylinder that is not used, for example, when printing a part of the paper surface in monochrome or two colors in color newspaper printing.

In the present disclosure, the “main chain” represents the relatively longest binding chain in the molecule of the polymer compound constituting the resin, and the “side chain” represents an atomic group branched from the main chain.
In the present disclosure, having an acid group in a side chain includes a mode in which an acid group is directly bonded to the main chain. That is, even when the acid group is a side group (pendant group), such as a case where a carboxy group (—C(═O)OH) is directly bonded to the main chain, a mode having an acid group in the side chain is used. included.
Hereinafter, the present disclosure will be described in detail.

(Lithographic printing plate original)
The lithographic printing plate precursor according to the present disclosure has a support, an image recording layer lower layer and an image recording layer upper layer in this order, and the image recording layer lower layer has a —SO ₂ —NH— structure having a pKa of less than 10. The polymer A having a unit, the image recording layer upper layer contains a polymer B having a structural unit having an acid group having a pKa of less than 10, and an infrared absorber, and the content of the polymer B is It is 30% by mass or more based on the total mass of the polymer contained in the upper layer of the image recording layer.
The lithographic printing plate precursor according to the present disclosure is preferably a positive lithographic printing plate precursor, and more preferably a thermal positive lithographic printing plate precursor.
The lithographic printing plate precursor according to the present disclosure has excellent developability and printing durability even after storage with time by adopting the above configuration. Although the detailed mechanism by which the above effects are obtained is unknown, it is presumed as follows.

In the image recording layer of the planographic printing plate precursor, the lower layer of the image recording layer contains a polymer having a low pKa —SO ₂ —NH— structure as a constitutional unit, and the upper layer of the image recording layer contains an acid group having a low pKa. By including the polymer having the constitutional unit having and the infrared absorbing agent, the upper layer and the lower layer of the image recording layer each include a polymer having a group having a low pKa, so that the diffusion of the infrared absorbing agent is suppressed and the upper layer of the image recording layer is suppressed. Therefore, even when the planographic printing plate is developed after storage with time, it is presumed that it has excellent developability (hereinafter, also referred to as “development with time”).
Further, since the polymer A and the polymer B contained in the upper layer or the lower layer of the image recording layer each have a —SO ₂ —NH— structure or an acid group, more hydrogen bonds are formed, and the above-mentioned infrared absorbing agent Since the diffusion is suppressed, it is presumed that the printing durability (hereinafter also referred to as “aging printing durability”) is excellent even after storage with time.

Further, since the polymer A and the polymer B contained in the upper layer or the lower layer of the image recording layer have high polarity, they are less likely to generate development debris and have a property of suppressing development debris even after storage with time (hereinafter, "deterioration property of development debris"). It is presumed that it is easy to excel.
Since the polymer A and the polymer B contained in the upper layer or the lower layer of the image recording layer each have a —SO ₂ —NH— structure or an acid group, more hydrogen bonds are formed, and the diffusion of the infrared absorber is prevented. Since it is suppressed, it is presumed that the ablation suppression property is also excellent. Further, for the same reason, since the image recording layer has high durability against a developing solution, it has excellent image part retention (hereinafter, also referred to as “aged image part retention”) even after storage with time. Estimated to be easy.
Hereinafter, details of each constituent element included in the planographic printing plate precursor according to the present disclosure will be described.

<Image recording layer lower layer>
The lithographic printing plate precursor according to the present disclosure has a support, an image recording layer lower layer (also simply referred to as “lower layer”), and an image recording layer upper layer in this order, and the image recording layer lower layer has a pKa of less than 10. Polymer A having a structural unit having a —SO ₂ —NH— structure of

[Polymer A]
The lower layer of the image recording layer in the present disclosure contains the polymer A having a structural unit having a —SO ₂ —NH— structure with a pKa of less than 10.

<<pKa of --SO ₂ --NH-- structure>>
The pKa of the —SO ₂ —NH— structure is preferably 3.5 or more and 8.5 or less from the viewpoints of the developability over time, the development debris suppression property over time, the image area retention property over time, and the printing durability over time. It is more preferably 4.0 or more and 7.5 or less, still more preferably 4.5 or more and 7.0 or less, and particularly preferably 4.0 or more and 7.0 or less.
The pKa in the present disclosure shall be calculated using ACD/Labs software Ver 8.0 for Microsoft windows ACD/pKa DB ver 8.07 manufactured by Advanced Chemistry Development.
PKa of -SO ₂ -NH- structure _is preferably a pKa of hydrogen atoms in the -SO 2 -NH- structure. Further, in the polymer A, the structure exhibiting the smallest pKa value is preferably a —SO ₂ —NH— structure.

The polymer A may be an addition polymerization type resin or a polycondensation resin, but from the viewpoint of time-developability, time-development-debris-retaining property, time-remaining image area retention property, and time-dependent printing durability, acrylic resin is used. A resin, a polyurea resin or a polyurethane resin is preferable, an acrylic resin or a polyurethane resin is more preferable, and an acrylic resin is particularly preferable.
As the acrylic resin, a resin in which the content of the structural unit formed by the (meth)acrylic compound (the structural unit derived from the (meth)acrylic compound) is 50% by mass or more is preferable.
Preferable examples of the (meth)acrylic compound include a (meth)acrylate compound and a (meth)acrylamide compound.
_-SO 2 -NH- structure in the polymer _A, the compound having a -SO 2 -NH- structure using _(monomers), is introduced into the polymer A as a structural unit containing an -SO 2 -NH- structure.

<<Example of --SO ₂ --NH-- structure>>
The above-mentioned —SO ₂ —NH— structure in the polymer A has a sulfonyl group (—SO ₂ —) in the —SO ₂ —NH— structure as an aromatic ring, from the viewpoints of retention of the image portion over time and printing durability over time. A direct bond is preferred.
In addition, the above-mentioned —SO ₂ —NH— structure in the polymer A has a nitrogen atom in the —SO ₂ —NH— structure which is an aromatic ring or a heteroaromatic ring, from the viewpoints of retention of image area over time and printing durability over time. A direct bond is preferred, and a direct bond to the heteroaromatic ring is more preferred.
Further, it is preferable that only one hydrogen atom is bonded to the nitrogen atom in the —SO ₂ —NH— structure. That is, it is preferable that no hydrogen atom is bonded to the —NH— side of the —SO ₂ —NH— structure.

In addition, the above-mentioned —SO ₂ —NH— structure in the polymer A has one of the following formulas 1 to 3 from the viewpoints of time-developability, time-development-debris-retaining property, image-retaining property over time, and printing durability over time. The structure represented by the formula is preferable, and the structure represented by the following formula 1 is more preferable.

In Formulas 1 to 3, Ar ₁ represents an arylene group, Ar ₂ represents an aryl group or a heteroaryl group, R ₁ represents a monovalent organic group, and * represents a bond with another structure. Represents a part.

Ar ₁ in Formulas 1 to 3 is preferably a group having a phenylene structure, more preferably a phenylene group, from the viewpoints of retention of image area over time and printing durability over time. A phenylene group is particularly preferable.
Ar ₂ in Formula 1 is preferably a heteroaryl group from the viewpoints of developability over time, development debris suppression property over time, image area retention property over time, and printing durability over time, and is a furan ring, isothiazoline ring, or isoxazoline ring. , Oxadiazoline ring, oxatriazine ring, oxazoline ring, pyrazine ring, pyridazine ring, pyridine ring, pyrimidine ring, tetrazine ring, thiadiazole ring, thiatriazole ring, thiazole ring, thiophene ring and triazine ring. A heteroaryl group having at least one heteroaromatic ring structure is more preferable, and at least one heteroaromatic ring structure selected from the group consisting of an isoxazoline ring, a pyridazine ring, a pyrimidine ring, a thiadiazole ring and a thiazole ring can be used. It is more preferably a heteroaryl group having a heteroaryl group, and particularly preferably a heteroaryl group having a thiadiazole ring.
Further, each heteroaromatic ring structure in the above heteroaryl group is preferably directly bonded to the nitrogen atom in the —SO ₂ —NH— structure. Further, each of the above heteroaromatic ring structures may have a substituent. Preferable examples of the substituent include an alkyl group, an aryl group and an alkoxy group.

R ₁ in Formulas 2 and 3 is preferably an alkyl group or an aryl group, more preferably an aryl group, and a phenyl group, from the viewpoints of the retention of the image area over time and the printing durability over time. Is particularly preferable.

Further, from the viewpoints of the time-development property, the time-development debris suppression property, the time-dependent image area retention property, and the time-dependent printing durability, Ar ₁ in Formula 1 is a group having a phenylene structure, and Ar ₂ is A heteroaryl group is preferable, Ar ₁ is a group having a phenylene structure, and Ar ₂ is a furan ring, isothiazoline ring, isoxazoline ring, oxadiazoline ring, oxatriazine ring, oxazoline ring, pyrazine ring. A heteroaryl group having at least one heteroaromatic ring structure selected from the group consisting of a pyridazine ring, a pyridine ring, a pyrimidine ring, a tetrazine ring, a thiadiazole ring, a thiatriazole ring, a thiazole ring, a thiophene ring and a triazine ring. More preferably, Ar ₁ is a group having a phenylene structure, and has a heteroaromatic structure having at least one heteroaromatic ring structure selected from the group consisting of an isoxazoline ring, a pyridazine ring, a pyrimidine ring, a thiadiazole ring and a thiazole ring. It is more preferably an aryl group, and it is particularly preferable that Ar ₁ is a phenylene group and Ar ₂ is a thiadiazolyl group or a 5-methylthiazolyl group.

As the structural unit having the —SO ₂ —NH— structure, the following formulas (SA1) to (SA3) are used from the viewpoints of time-developability, time-development-debris-retaining property, time-retention of image area, and time-dependent printing durability. ) Is more preferable, and a structural unit represented by the following formula (SA1) is more preferable.

In formulas (SA1) to (SA3), Ar ₁ represents an arylene group, Ar ₂ represents an aryl group or a heteroaryl group, R ₁ represents a monovalent organic group, and R ₂ represents hydrogen. Represents an atom or a methyl group, X ₁ represents —NR ₃ — or —O—, and R ₃ represents a hydrogen atom, an alkyl group or an aryl group.

_Ar 1, Ar ₂ and _{R 1} in formula (SA1) to Formula (SA3) has the same meaning as _Ar 1, Ar ₂ and _{R 1} in Formula 1 to Formula 3, preferred embodiment is also the same.
R ₂ in formulas (SA1) to (SA3) is preferably a methyl group.
X ₁ in formulas (SA1) to (SA3) is preferably —NR ₃ —, and more preferably —NH— from the viewpoints of developability over time and development debris controllability over time.
R ₃ in formulas (SA1) to (SA3) is preferably a hydrogen atom or an alkyl group, and more preferably a hydrogen atom.

As specific examples of the structural unit having the —SO ₂ —NH— structure, the structural units shown in Examples described later can be preferably cited.

The polymer A may have one kind of structural unit having a —SO ₂ —NH— structure, or may have two or more kinds.
The content of the constitutional unit having a —SO ₂ —NH— structure in the polymer A is the total mass of the polymer A from the viewpoints of time-developability, time-development-debris-retaining property, image-retaining property over time, and printing durability over time. On the other hand, it is preferably 30% by mass or more, more preferably 50% by mass or more, further preferably 55% by mass or more and 100% by mass or less, and 65% by mass or more and 98% by mass or less. Is particularly preferable, and most preferably 75% by mass or more and 95% by mass or less.

<<Other structural units>>
The polymer A preferably has a constitutional unit other than the constitutional unit having a —SO ₂ —NH— structure from the viewpoints of developability with time, retention of image area with time, and printing durability with time.
Other structural units are not particularly limited, but are selected from the group consisting of (meth)acrylate compounds, (meth)acrylamide compounds, styrene, acrylonitrile, N-vinyl-ε-caprolactam, and N-phenylmaleimide. Constitutional units derived from at least one compound may be mentioned.
Among them, the other structural unit is preferably a structural unit derived from at least one compound selected from the group consisting of (meth)acrylate compounds and (meth)acrylamide compounds, and alkyl (meth)acrylate compounds. , And a structural unit derived from at least one compound selected from the group consisting of (meth)acrylamide compounds, and more preferably from the group consisting of alkyl methacrylate compounds and N-aryl-substituted (meth)acrylamide compounds. It is particularly preferable that the structural unit is derived from at least one selected compound.
In addition, the above-mentioned other structural units in the polymer A are structural units represented by the following formula (M1) or the following formula (M2) from the viewpoints of time-developability, time-dependent image area retention, and time-dependent printing durability. It is preferable to have

In formula (M1), R ₄ represents a hydrogen atom or a methyl group, and R ₅ represents an alkyl group or an aryl group.

In the formula (M2), R ₆ represents a hydrogen atom or a methyl group, and R ₇ represents an alkyl group or an aryl group.

R ₄ in formula (M1) is preferably a methyl group.
The alkyl group and aryl group for R ₅ in formula (M1) may have a substituent. Examples of the substituent include an alkyl group, an aryl group, a hydroxy group, an alkoxy group and the like. Of these, an alkyl group, a phenyl group and a hydroxy group are preferable.
The carbon number (the number of carbon atoms) of R ₅ in the formula (M1) is preferably 1 to 20, and preferably 1 to 8 from the viewpoints of the developability with time, the retention of the image area with time, and the printing durability with time. It is more preferable to be present, and it is particularly preferable to be 1 to 4.
R ₅ in the formula (M1) is preferably an alkyl group, a hydroxyalkyl group, or an aralkyl group, from the viewpoints of developability with time, retention of image area with time, and printing durability with time. It is more preferably an ethyl group or a benzyl group, further preferably an alkyl group, and particularly preferably a methyl group.

R ₆ in formula (M2) is preferably a methyl group.
The alkyl group and aryl group for R ₇ in formula (M2) may have a substituent. Examples of the substituent include an alkyl group, an aryl group, a hydroxy group, an alkoxy group, a sulfonamide group and the like. Of these, a phenyl group, a hydroxy group, and a sulfonamide group are preferable.
The carbon number (the number of carbon atoms) of R ₇ in the formula (M2) is preferably 1 to 20, and preferably 1 to 8 from the viewpoints of developability with time, retention of image area with time, and printing durability with time. It is more preferable to be present, and it is particularly preferable to be 1 to 4.
R ₇ in the formula (M2) is preferably an aryl group, more preferably a phenyl group, and more preferably a hydroxy group or a sulfone from the viewpoints of developability with time, retainability of image area with time, and printing durability with time. More preferably, it is a phenyl group substituted with an amide group.

-Content of Polymer A-
The polymer A may have one kind of other structural unit alone or may have two or more kinds thereof.
The content of the other structural units in the polymer A is 70% by mass or less based on the total mass of the polymer A from the viewpoints of the developability over time, the development debris suppression property over time, the image area retention property over time, and the printing durability over time. Is preferable, 50% by mass or less is more preferable, 45% by mass or less is further preferable, 2% by mass or more and 35% by mass or less is particularly preferable, 5% by mass or more and 25% by mass Most preferably it is

<<Acid Value of Polymer A>>
The acid value of the polymer A is preferably 1.0 meq/g to 3.5 meq/g, and 1.3 meq/g to 3.0 meq, from the viewpoints of the developability over time, the development debris suppression property over time, and the printing durability over time. /G is more preferable, 1.5 meq/g to 2.0 meq/g is further preferable, and 2.2 meq/g to 2.8 meq/g is particularly preferable.
The acid value of the polymer A in the present disclosure is represented by the number of moles of potassium hydroxide necessary to neutralize 1 g of the polymer A, and the value determined by the measurement method according to JIS standard (JIS K0070:1992) should be used. You can

-Weight average molecular weight of polymer A-
The weight average molecular weight of the polymer A is preferably from 5,000 to 30,000, more preferably from 8,000 to 22,000, from the viewpoints of printing durability with time and abrasion resistance. , 500 to 20,000 is more preferable.

The lower layer of the image recording layer may contain the polymer A alone or in combination of two or more.
The content of the polymer A in the lower layer of the image recording layer is 10% by mass with respect to the total mass of the lower layer of the image recording layer from the viewpoints of time-developability, time-development-debris-retaining property, time-retention of image area, and time-dependent printing durability. % To 99 mass% is preferable, 20 mass% to 95 mass% is more preferable, and 30 mass% to 90 mass% is further preferable.

The polymer A is produced, for example, by a known method. For example, the polymer A can be obtained as a polymer by applying energy such as heating or exposure using a composition containing a monomer used for 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 a known document.

[Infrared absorber]
In the lithographic printing plate precursor according to the present disclosure, the lower layer of the image recording layer preferably contains an infrared absorber.
The infrared absorbent is not particularly limited as long as it is a dye that absorbs infrared light and generates heat, and various dyes known as infrared absorbents can be used.
As the infrared absorber that can be used in the present disclosure, commercially available dyes and known ones described in the literature (for example, “Handbook of Dyes” edited by the Society of Synthetic Organic Chemistry, published in 1970) can be used. Specific examples 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, among these dyes, those that absorb at least infrared light or near infrared light are preferable in that they are suitable for use in a laser that emits infrared light or near infrared light, and cyanine dyes are particularly preferable. preferable.

Examples of such dyes that absorb at least infrared light or near infrared light include, for example, JP-A-58-125246, JP-A-59-84356, JP-A-59-202829, and JP-A-60-. Cyanine dyes described in JP-A-78787 and the like, methine dyes described in JP-A-58-173696, JP-A-58-181690 and JP-A-58-194595, and JP-A-58-112793, JP-A-58-224793, JP-A-59-48187, JP-A-59-73996, JP-A-60-52940, JP-A-60-63744 and the like. Examples thereof include naphthoquinone dyes described in JP-A-58-112792, squarylium dyes described in JP-A-58-112792, and cyanine dyes described in British Patent 434,875.
Further, a near infrared absorption sensitizer described in US Pat. No. 5,156,938 is also preferably used as a dye, and a substituted arylbenzo described in US Pat. No. 3,881,924 is also used. (Thio)pyrylium salt, the trimethine thiapyrylium salt described in JP-A-57-142645 (US Pat. No. 4,327,169), JP-A-58-181051, JP-A-58-220143, and JP-A-58-220143. 59-41363, 59-84248, 59-84249, 59-146063, 59-146061 and pyrylium compounds described in JP-A-59-216146. Cyanine dyes, pentamethine thiopyrylium salts described in U.S. Pat. No. 4,283,475, and pyrylium compounds disclosed in Japanese Patent Publication Nos. 5-13514 and 5-19702 are commercially available products. Particularly preferably used are Epolight III-178, Epolight III-130, and Epolight III-125 manufactured by Eporin.
Another particularly preferable example of the dye is a near-infrared absorbing dye described as formulas (I) and (II) in US Pat. No. 4,756,993.
Among them, (I-1) to (I-30) described in US Pat. No. 4,756,993, columns 7 to 17 are preferable.

Particularly preferred among these dyes are cyanine dyes, phthalocyanine dyes, oxonol dyes, squarylium dyes, pyrylium salts, thiopyrylium dyes, and nickel thiolate complexes. Furthermore, the cyanine dye represented by the following formula (a) is particularly preferable because it is excellent in stability and economy when used in the lower layer of the image recording layer.

In Formula (a), X ¹ represents a hydrogen atom, a halogen atom, a diarylamino group (—NPh ₂ ), —X ² —L ¹ or a group shown below, and X ² represents an oxygen atom or a sulfur atom. , L ¹ represents a hydrocarbon group having 1 to 12 carbon atoms, an aromatic group having a hetero atom, or a hydrocarbon group having 1 to 12 carbon atoms having a hetero atom. Here, the hetero atom represents N, S, O, a halogen atom, or Se. Further, Ph represents a phenyl group.

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

R ²¹ and R ²² each independently represent a hydrocarbon group having 1 to 12 carbon atoms. From the storage stability of the lithographic printing plate precursor, R ²¹ and R ²² are preferably a hydrocarbon group having 2 or more carbon atoms, and further, R ²¹ and R ²² are bonded to each other to form a 5-membered ring or 6-membered ring. It is particularly preferable that a ring is formed.

Ar ¹ and Ar ^{2, which} may be the same or different, each represents an aromatic hydrocarbon group which may have a substituent. A benzene ring and a naphthalene ring are mentioned as a preferable aromatic hydrocarbon group. Moreover, as a preferable substituent, a C12 or less hydrocarbon group, a halogen atom, and a C12 or less alkoxy group are mentioned.
Y ¹¹ and Y ¹² may be the same or different and each represents a sulfur atom or a dialkylmethylene group having 12 or less carbon atoms. R ²³ and R ^{24, which} may be the same or different, each represents a hydrocarbon group having 20 or less carbon atoms which may have a substituent. Preferable substituents include an alkoxy group having 12 or less carbon atoms, a carboxy group and a sulfo group.
R ²⁵ , R ²⁶ , R ²⁷ and R ^{28, which} may be the same or different, each represents a hydrogen atom or a hydrocarbon group having 12 or less carbon atoms. From the availability of raw materials, hydrogen atom is preferable. Za ⁻ represents a counter anion. However, when the cyanine dye represented by the formula (a) has an anionic substituent in its structure and charge neutralization is not necessary, Za ⁻ is not necessary. Preferred Za ⁻ is a halide ion, a perchlorate ion, a tetrafluoroborate ion, a hexafluorophosphate ion or a sulfonate ion from the storage stability of the lithographic printing plate precursor, and particularly preferably, a perchlorate ion or a hexachlorate ion. It is a fluorophosphate ion or an aryl sulfonate ion.

Specific examples of the cyanine dye represented by formula (a) that can be preferably used include, for example, paragraphs 0017 to 0019 of JP 2001-133969 A, paragraphs 0012 to 0038 of JP 2002-40638 A, and JP Examples thereof include those described in paragraphs 0012 to 0023 of 2002-23360.
The cyanine dye A shown below is particularly preferable as the infrared absorber contained in the lower layer of the image recording layer.

The lower layer of the image recording layer may contain an infrared absorber alone or in combination of two or more.
The content of the infrared absorbent 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 of the image recording layer. It is particularly preferably from 1.0% by mass to 30% by mass. When the addition amount is 0.01% by mass or more, the sensitivity becomes high, and when the addition amount 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 lower layer of the image recording layer in the present disclosure may further contain other binder polymer.
The lower layer of the image recording layer is selected from the 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 the other binder polymer. It is preferable to further include at least one kind.
The other binder polymer is preferably an alkali-soluble resin.

The lower layer of the image recording layer may contain the other binder polymer alone or in combination of two or more kinds.
The content of the other binder polymer in the lower layer of the image recording layer is preferably smaller than the content of the polymer A.
The content of the other binder polymer is preferably 10% by mass or less, more preferably 5% by mass, further preferably 1% by mass, based on the total mass of the lower layer of the image recording layer. It is particularly preferable that the lower layer of the image recording layer contains no other binder polymer.

[Acid generator]
The lower layer of the image recording layer in the present disclosure preferably contains an acid generator from the viewpoint of improving the sensitivity of the lithographic printing plate precursor obtained.
In the present disclosure, the acid generator is a compound that generates an acid by light or heat, and refers to a compound that decomposes to generate an acid when irradiated with infrared rays or heated at 100° C. or higher. The generated acid is preferably a strong acid having a pKa of 2 or less such as sulfonic acid and hydrochloric acid. The acid generated from the acid generator enhances the permeability of the developing solution into the exposed area of the lithographic printing plate precursor, and further improves the solubility of the image recording layer in the alkaline aqueous solution.
Examples of the acid generator preferably used in the lower layer of the image recording layer in the present disclosure include the acid generators described in paragraphs 0116 to 0130 of WO 2016/047392.
Above all, it is preferable to use an onium salt compound as the acid generator from the viewpoint of sensitivity and stability. The onium salt compound will be described below.
Examples of the onium salt compound that can be preferably used in the present disclosure include compounds known as compounds that generate an acid by being decomposed by infrared radiation and thermal energy generated from the infrared absorber upon exposure. Examples of onium salt compounds suitable for the present disclosure include known thermal polymerization initiators and compounds having an onium salt structure described below having a bond with 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 them, triarylsulfonium or diaryliodonium sulfonates. , Carboxylate, BF ₄ ⁻ , PF ₆ ⁻ , ClO ₄ ^{− and the} like are preferable.
Examples of onium salts that can be used as the acid generator in the present disclosure include onium salts represented by any of the following formulas III to V.

In Formula III, Ar ¹¹ and Ar ¹² each independently represent an aryl group having 20 or less carbon atoms, which may have a substituent. When the aryl group has a substituent, a preferable substituent is a halogen atom, a nitro group, an alkyl group having 12 or less carbon atoms, an alkoxy group having 12 or less carbon atoms, or an aryloxy group having 12 or less carbon atoms. .. Z ^11- is a pair selected from the group consisting of halide ion, perchlorate ion, tetrafluoroborate ion, hexafluorophosphate ion, sulfonate ion, and sulfonate ion having a fluorine atom such as perfluoroalkylsulfonate ion. Represents an ion, and is preferably a perchlorate ion, a hexafluorophosphate ion, an aryl sulfonate 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 are a halogen atom, a nitro group, an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aryloxy group having 1 to 12 carbon atoms, an alkylamino group having 1 to 12 carbon atoms, Examples thereof include a dialkylamino group having 2 to 12 carbon atoms, an arylamino group having 6 to 12 carbon atoms, and a diarylamino group (the carbon numbers of two aryl groups are each independently 6 to 12). Z ^21- represents a counter ion having the same ^meaning as Z ^11- .
In the above formula V, R ³¹ , R ³² and R ^{33, which} may be the same or different, each represents a hydrocarbon group having 1 to 20 carbon atoms which may have a substituent. Examples of preferable 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, and an aryloxy group having 1 to 12 carbon atoms. Z ³¹⁻ represents a counter ion having the same ^meaning as Z ¹¹⁻ .

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

Further, as another example of the compounds represented by the formulas III to V, the compounds described as examples of the radical polymerization initiator in paragraphs 0036 to 0045 of JP 2008-195018 are related to the present disclosure. It can be suitably used as an acid generator.

More preferred examples of the acid generator usable in the present disclosure include the following compounds (PAG-1) to (PAG-5).

When these acid generators are contained in the lower layer of the image recording layer in the present disclosure, these compounds may be used alone or in combination of two or more kinds.
The content of the acid generator is preferably 0.01% by mass to 50% by mass, more preferably 0.1% by mass to 40% by mass, and more preferably 0.5% by mass, based on the total mass of the lower layer of the image recording layer. % To 30% by mass is more preferable. When the content is in the above range, the sensitivity which is the effect of the addition of the acid generator is improved, and the generation of the residual film in the non-image area is suppressed.

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

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

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

[Other additives]
The lower layer of the image recording layer in the present disclosure may contain, as other additives, a development accelerator, a surfactant, a printout agent, a colorant, a plasticizer, a wax agent and the like.

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

-Surfactant-
The lower layer of the image recording layer in the present disclosure is described in JP-A No. 62-251740 and JP-A No. 3-208514 in order to improve the coating property and to broaden the stability of processing under developing conditions. Such nonionic surfactants, amphoteric surfactants described in JP-A-59-121044 and JP-A-4-13149, JP-A-62-170950 and JP-A-11- Fluorine-containing monomer copolymers such as those described in JP-A-288093 and JP-A-2003-57820 can be added.
Specific examples of the nonionic surfactant include sorbitan tristearate, sorbitan monopalmitate, sorbitan trioleate, stearic acid monoglyceride, and polyoxyethylene nonylphenyl ether.
Specific examples of the amphoteric surfactant include alkyldi(aminoethyl)glycine, alkylpolyaminoethylglycine hydrochloride, 2-alkyl-N-carboxyethyl-N-hydroxyethylimidazolinium betaine and N-tetradecyl-N,N-. Examples thereof include betaine type (for example, trade name "Amogen K": manufactured by Daiichi Kogyo Seiyaku Co., Ltd.).
The ratio of the surfactant to the total weight of the lower layer 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. Mass% is more preferable.

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

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

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

<Upper layer of image recording layer>
The lithographic printing plate precursor according to the present disclosure has a support, an image recording layer lower layer, and an image recording layer upper layer (hereinafter, also simply referred to as “upper layer”) in this order, and the image recording layer upper layer has a pKa of less than 10. Polymer B having a structural unit having an acid group and an infrared absorber, and the content of the polymer B is 30% by mass or more based on the total mass of the polymer contained in the upper layer of the image recording layer. is there.

[Polymer B]
The upper layer of the image recording layer contains the polymer B having a structural unit having an acid group having a pKa of less than 10.

<<pKa of acid group>>
The pKa of the acid group is less than 10, and is preferably 7.0 or less from the viewpoints of developability with time, retention of image area with time, and printing durability with time, and is 3.0 or more and 7.0 or less. It is more preferable that it is from 3.5 to 6.0, further preferably from 3.5 to 6.0, and particularly preferably from 4.0 to 5.5.
Further, in the polymer B, the structure having the smallest pKa value is preferably an acid group in a structural unit having an acid group.

In the lithographic printing plate precursor according to the present disclosure, the difference value obtained by subtracting the pKa of the polymer B contained in the upper layer of the image recording layer from the pKa of the polymer A contained in the lower layer of the image recording layer ((-SO ₂ -NH- in the polymer A The pKa)-(pKa of the acid group in the polymer B) of the structure is preferably more than 0, and is 0.5 or more and 5.0 or less, from the viewpoint of the retention of the image area over time and the printing durability over time. It is more preferably 1.5 or more and 4.5 or less, still more preferably 2.0 or more and 4.0 or less.

-Content of Polymer B-
The content of the polymer B is 30% by mass or more based on the total mass of the polymer contained in the upper layer of the image recording layer, and the time-developability, the time-development debris suppression property, the time-dependent image area retention, the time-dependent printing durability, and the From the viewpoint of ablation suppression property, it is preferably 50% by mass to 100% by mass, more preferably 70% by mass to 100% by mass, and particularly preferably 85% by mass to 100% by mass.

The polymer B may be an addition polymerization type resin or a polycondensation resin, but from the viewpoint of time-developability, time-development-debris-retaining property, image-retaining property with time, and printing durability with time, A resin or a phenol resin is preferable, an acrylic resin or a novolac resin is more preferable, and an acrylic resin is particularly preferable.
The phenol resin may be a resin obtained by polycondensing at least a phenol compound and formaldehyde, preferably a novolac resin and a resole resin, more preferably a novolac resin.

Further, the polymer B is preferably an alkali-soluble resin, more preferably a weak alkali-soluble resin that is soluble in weak alkali.
In the present disclosure, “alkali-soluble” refers to being soluble in a 1 mol/L sodium hydroxide solution at 25° C., and “weakly alkali-soluble” refers to a 0.0001 mol/L sodium hydroxide solution (pH 10) at 25° C. It is soluble.
Further, "soluble" means that 0.1 g or more is dissolved in 100 mL of solvent.

<< acid group >>
The polymer B contains a structural unit having an acid group.
The acid group is preferably introduced into the polymer B as a constitutional unit containing an acid group using a monomer capable of forming an acid group.

<<Example of acid group>>
The acid group in the polymer B is not particularly limited, and examples thereof include a carboxy group, a sulfo group, a phosphoric acid group, a phosphonic acid group, and a sulfuric acid group. Among them, as the acid group, a carboxy group is preferable from the viewpoints of time-development property, time-development-debris suppression property, and time-dependent printing durability and ablation property suppression property.
Further, the phenolic hydroxyl group (phenolic hydroxy group) usually has a pKa of 10 or more, and thus is not included in the acid group in the polymer B.
The polymer B may further have an acid group having a pKa of 10 or more, but the content of the acid group having a pKa of 10 or more is preferably 0.1 moL/g or less from the viewpoint of developability, It is more preferably 0.01 moL/g or less.

<<ClogP Value of Structural Unit Having Acid Group>>
The ClogP value of the structural unit having an acid group is preferably 0.3 to 5, and more preferably 1.0 to 4.0 from the viewpoints of developability with time, printing durability with time, and ink receptivity. More preferably, it is more preferably 2.0 to 3.8.
The ClogP value is a value obtained by calculating the common logarithm logP of the partition coefficient P between 1-octanol and water. Known methods and software can be used for calculating the ClogP value, but unless otherwise specified, the ClogP program incorporated in ChemBioDraw Ultra 12.0 of Cambridge software is used in the present disclosure.
Further, in the calculation of the ClogP value, a hydrogen atom is substituted for a connecting site (that is, * in the following structural unit) of a structural unit (preferably a monomer unit) having an acid group.
For example, when calculating the ClogP value of the following structural unit UA-1, the ClogP value is calculated after conversion into the following structure UA'-1.

<<Acid Value of Polymer B>>
The acid value of the polymer B is preferably 1.0 meq/g to 3.5 meq/g, and more preferably 1.5 meq/g to 1.9 meq, from the viewpoints of the developability over time, the development debris controllability over time, and the printing durability over time. /G is more preferable, and 1.5 meq/g to 1.75 meq/g is further preferable.

-Structural unit having a basic group-
The polymer B preferably further contains a structural unit having a basic group from the viewpoints of printing durability with time and developability with time.
The base group is preferably introduced into the polymer B as a constitutional unit containing the base group by using a monomer capable of forming the base group.

<<pKaH of basic group>>
When the polymer B further contains a structural unit having a basic group, the pKaH of the basic group is preferably 4 or more, more preferably 5 or more, and more preferably 8 or more from the viewpoint of developability with time. Is more preferable.
The upper limit of pKaH of the basic group is not particularly limited, but is preferably 12 or less, more preferably 9 or less.
The base group pKaH means the pKa of an acid conjugated to the base group.
The pKaH in the present disclosure is calculated using ACD/Labs software Ver 8.0 for Microsoft windows ACD/pKa DB ver 8.07 manufactured by Advanced Chemistry Development.

<<Example of base group>>
The basic group in the polymer B is not particularly limited, and examples thereof include an amino group and an aromatic ring containing a nitrogen atom. From the viewpoint of developability with time, printing durability with time, and abrasion resistance, a tertiary amino group or pyridyl is used. A group is more preferable, and a tertiary amino group is particularly preferable.
Further, in the polymer B, it is preferable that the acid group is a carboxy group and the base group is a tertiary amino group or a pyridyl group, from the viewpoints of the developability with time, the printing durability with time, and the abrasion resistance. More preferably, the acid group is a carboxy group and the base group is a tertiary amino group.

<<ClogP value of constitutional unit having basic group>>
The ClogP value of the structural unit having a basic group is preferably −1.0 to 10 and more preferably 1.0 to 5.0 from the viewpoints of developability with time, printing durability with time, and abrasion resistance. More preferable.
The ClogP value of the structural unit having a base group is determined by the same method as the ClogP value of the structural unit having an acid group described above. For example, when calculating the ClogP value of the structural unit UB-1 below, the ClogP value is calculated after conversion into the structure UB′-1 below.

<<Base number of polymer B>>
The base number of the polymer B is preferably 1.5 meq/g to 1.9 meq/g, and more preferably 1.5 meq/g to 1.75 meq/g.
In the present specification, the base number of the polymer B means the base number determined by the perchloric acid method defined by JIS K 2501 (2003). The base number is obtained as the number of milligrams (mg) of potassium hydroxide equivalent to hydrochloric acid or perchloric acid required to neutralize all the basic components contained in 1 g of the sample.

Further, the ratio of the number of moles of acid groups/the number of moles of base groups in the polymer B is preferably 0.90/1.0 to 1.0/0.90, and 0.95/1.0 to 1 0.0/0.95 is more preferable.

-Specific structure of structural unit having acid group and structural unit having basic group-
In the polymer B, the chain length between the acid group or the base group and the main chain is preferably 3 or more atoms from the viewpoints of the time-development property and the ablation suppression property. More preferably, the chain length between is 5 or more atoms.
The chain length between the acid group or the base group and the main chain is a value obtained by counting the number of side chain atoms connecting the main chain in the polymer B and the acid group or the base group so as to be the minimum. Atoms contained in the main chain are not included in the chain length number.
The chain constituting the above chain length is a group consisting of an alkyl chain, an ether bond (-O-), an amide bond (-C(=O)NH-, and an ester bond (-C(=O)O-). It is preferably a chain containing at least one selected from the following.
The alkyl chain is preferably a branched or linear saturated alkyl chain, and more preferably a linear alkyl chain, from the viewpoint that the acid group and base group contained in the polymer B easily form a salt.
For example, in the case of the structure below, the chain length is 5.

Further, for example, in the case of the following structure, the above chain length is 1.

<<Formula A1 and Formula B1>>
The constituent unit having an acid group is preferably a constituent unit represented by the following formula A1.
Further, the structural unit having a basic group is preferably a structural unit represented by the following formula B1.
In the present disclosure, the constitutional unit represented by the formula A1 may be referred to as “constitutional unit A1”, and the constitutional unit represented by the formula B1 may be referred to as “constitutional unit B1”.

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 less than 10. It represents an acid group, and * each independently represents a binding site with another structure.
In formula B1, R ^2B represents a hydrogen atom or a methyl group, X ^2B represents a single bond, an ester bond or an amide bond, L ^2B represents a single bond or a divalent linking group, Base represents a base group, L ² and the atom contained in Base may form a ring.

<< Formula A1 >>
In formula A1, X ^1A is preferably an ester bond or an amide bond.
When X ^1A represents an ester bond, the carbon atom in the ester bond is preferably bonded to the main chain side of the polymer B.
Further, when 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 polymer B.
In formula A1, L ^1A is preferably a single bond or a divalent hydrocarbon group which may have an ester bond or an ether bond inside, and is preferably a single bond or a divalent hydrocarbon group. More preferably, it is a single bond or a divalent saturated aliphatic hydrocarbon group, still more preferably. When L ^1A represents a divalent hydrocarbon group, the carbon number of L ^1A is preferably 2 or more, more preferably 2 to 15, and even more preferably 3 to 12.
In Formula A1, Acid is preferably an acid group having a pKa of 7 or less, and more preferably a carboxy group.
* Each independently represents a binding site with another structure.

<< Formula B1 >>
In formula B1, L ^2B is preferably a single bond or a divalent hydrocarbon group which may have a urea bond or an ether bond, more preferably a single bond or a divalent hydrocarbon group, and a single bond or a divalent hydrocarbon group. More preferably, it is an aliphatic saturated hydrocarbon group. When L ^2B represents a divalent hydrocarbon group, the carbon number of L ^2B is preferably 1 or more, more preferably 2 to 10, and even more preferably 2 to 8.
In Formula B1, Base is preferably a tertiary amino group or a pyridyl group.
L ^2B and the atom contained in Base may combine with each other to form a ring, and the ring formed is preferably a tetramethylpiperidine ring or the like.
* Each independently represents a binding site with another structure.

<<Expression a and Expression b>>
The structural unit A1 is preferably a structural unit represented by the following formula a.
Further, the structural unit B1 is preferably a structural unit represented by the following formula b.

In formula a, R ^3A represents a hydrogen atom or a methyl group, X ^3A represents —O— or —NR ^7A —, R ^7A represents a hydrogen atom or an alkyl group, and L ^3A represents a single bond or a carbon number. It represents one or more divalent hydrocarbon groups, and * each independently represents a binding site with another structure.
In formula b, R ^4B represents a hydrogen atom or a methyl group, X ^4B represents —O— or —NR ^8B —, R ^8B represents a hydrogen atom or an alkyl group, L ^4B , R ^5B and R ^6B At least two of them may combine to form a ring, L ^4B represents a single bond or a divalent hydrocarbon group having 1 or more carbon atoms, and R ^5B and R ^6B each independently have a carbon number. It represents one or more monovalent hydrocarbon groups, and * each independently represents a binding site with another structure.

<< formula a >>
In formula a, when X ^3A represents —NR ^7A , R ^7A 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 more preferably a hydrogen atom. Is more preferable.
In formula a, L ^3A represents a single bond or a divalent hydrocarbon group having 1 or more carbon atoms, and is a single bond or a divalent hydrocarbon group which may have an ester bond or an ether bond therein. Is more preferable, a single bond or a divalent hydrocarbon group is more preferable, and a single bond or a divalent aliphatic saturated hydrocarbon group is further preferable. When L ^3A represents a divalent hydrocarbon group, the number of carbon atoms in L ^3A is more preferably 2-15, and even more preferably 3-12.

Preferred specific examples of the structural unit having an acid group are shown below, but the structural unit having an acid group is not limited thereto.

The polymer B may have one type of structural unit having an acid group, or may have two or more types.
The content of the structural unit having an acid group (preferably the structural unit A1, more preferably the structural unit a) is preferably 5% by mass or more and 70% by mass or less with respect to the total mass of the polymer B, and 10% by mass. % Or more and 50 mass% or less is more preferable.

<< formula b >>
In formula b, when X ^4B represents —NR ^8B , R ^8B 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 more preferably a hydrogen atom. Is more preferable.
In formula b, L ^4B represents a single bond or a divalent hydrocarbon group having 1 or more carbon atoms, preferably a single bond or a divalent hydrocarbon group which may have a urea bond or an ether bond, and a single bond Alternatively, a divalent hydrocarbon group is more preferable, and a single bond or a divalent aliphatic saturated hydrocarbon group is further preferable. The carbon number of L ^4B is more preferably 2-10, and even more preferably 2-8.
In formula b, at least two members out of L ^4B , R ^5B and R ^6B may combine to form a ring, and the formed ring is preferably a tetramethylpiperidine ring or the like.
R ^5B and R ^6B each independently represent a monovalent hydrocarbon group having 1 or more carbon atoms, and preferably an aliphatic saturated hydrocarbon group having 1 or more carbon atoms. The carbon number of R ^5B and R ^6B is preferably 1-10.
In the formula b, N is a nitrogen atom contained in the tertiary amino group.

Preferred specific examples of the structural unit having a base group are shown below, but the structural unit having a base group is not limited thereto.

The content of the structural unit having a basic group (preferably the structural unit B1, more preferably the structural unit b) is preferably 5% by mass or more and 70% by mass or less with respect to the total mass of the polymer B, and 10% by mass. % Or more and 50 mass% or less is more preferable.

<<Other structural units>>
The polymer B preferably further contains a constitutional unit other than the constitutional unit having an acid group and the constitutional unit having a basic group.
Examples of the other structural unit include a structural unit formed by a (meth)acrylate compound, a (meth)acrylamide compound, a styrene compound and the like, but a structural unit formed by a (meth)acrylate compound is preferable, and From the viewpoint of sex, a structural unit formed of a (meth)acrylate compound having no hydrophilic group is more preferable.

<<(meth)acrylate compound>>
The content of the structural unit formed by the (meth)acrylate compound is preferably 0.1% by mass or more and 50% by mass or less, and preferably 5% by mass or more and 30% by mass, based on the total mass of the polymer B. Is more preferable.
The (meth)acrylate compound may be a monofunctional (meth)acrylate compound having one (meth)acryloxy group in one molecule, and may have two or more (meth)acryloxy groups in one molecule. Although it may be a polyfunctional (meth)acrylate compound, a monofunctional (meth)acrylate compound is preferable from the viewpoint of developability with time.
From the viewpoint of ink receptivity and scratch resistance, the (meth)acrylate compound does not have a hydrophilic group, and is preferably a monofunctional (meth)acrylate compound, does not have a hydrophilic group, and, A monofunctional methacrylic acid ester compound is more preferable.
Examples of monofunctional methacrylate compounds having no hydrophilic group include alkyl methacrylate compounds and cycloalkyl methacrylate compounds. These may have a substituent other than the hydrophilic group.
Among the above, methacrylic acid alkyl ester having an alkyl group having 1 to 12 carbon atoms is preferable from the viewpoint of ink receptivity.
Specific examples of the alkyl methacrylate compound having an alkyl group having 1 to 12 carbon atoms include methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate and the like.

-Molecular weight of polymer B-
The weight average molecular weight of the polymer B is preferably 5,000 to 200,000, and more preferably 8,000 to 100,000 from the viewpoints of the developability with time and the printing durability with time.

-Content of Polymer B-
The upper layer of the image recording layer may contain the polymer B alone or in combination of two or more.
The content of the polymer B is preferably 10% by mass to 99% by mass, more preferably 20% by mass to 95% by mass, and further preferably 30% by mass to 90% by mass with respect to the total mass of the upper layer of the image recording layer. % Is more preferable.

The polymer B is produced, for example, by a known method. For example, the polymer B can be obtained as a polymer by applying energy such as heating or exposure using a composition containing a monomer used for 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 a known document.

Specific examples of the polymer B are shown below, but the present disclosure is not limited thereto.
In the following specific examples, the description in the column of each structural unit represents the same structural unit as the symbol shown in the specific example of each structural unit described above.
In the following specific examples, the description of the content of each structural unit represents the content (mass ratio) of each structural unit with respect to the total mass of the polymer B. The structural units indicated by the descriptions of MMA, EHMA, and BnMA will be described later.

The constituent units described as MMA, EHMA, and BnMA in the other constituent units 1 are constituent units having the following structures, respectively.

[Infrared absorber]
The upper layer of the image recording layer in the lithographic printing plate precursor according to the present disclosure contains an infrared absorber.
The preferred embodiment of the infrared absorbent used in the upper layer of the image recording layer is the same as the preferred embodiment of the infrared absorbent used in the lower layer of the image recording layer.

[Other binder polymers]
The upper layer of the image recording layer may further contain a binder polymer other than the polymer B.
The image recording layer is selected from the 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 the other binder polymer. It is preferable to further include at least one kind.
The other binder polymer is preferably an alkali-soluble resin, and more preferably a weak alkali-soluble resin.

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

The weight average molecular weight of the phenol resin is preferably more than 2,000 and 50,000 or less, more preferably 2,500 to 20,000, and particularly preferably 3,000 to 10,000. .. The dispersity (weight average molecular weight/number average molecular weight) is preferably 1.1 to 10.
The number average molecular weight is a polystyrene equivalent number average molecular weight measured by gel permeation chromatography (GPC) using tetrahydrofuran (THF) as a solvent.
Such phenolic resins may be used alone or in combination of two or more.
The content of the phenol resin in the upper layer of the image recording layer in the present disclosure is preferably 1% by mass to 90% by mass with respect to the total mass of the polymer B, from the viewpoint of obtaining a lithographic printing plate precursor excellent in image forming property. It is more preferably from 50% by mass to 50% by mass, and particularly preferably from 10% by mass to 30% by mass.

-Resin containing an acidic group in the side chain-
Examples of the other binder polymer include 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 its main chain.
As these resins, resins having the acidic groups listed in the following (1) to (6) in the side chain of the polymer can be preferably used.

(1) Phenolic hydroxyl group (-Ar-OH)
(2) Sulfonamide group (-SO ₂ NH-R)
(3) Substituted sulfonamide acid group (hereinafter referred to as "active imide group")
[-SO ₂ NHCOR, -SO ₂ NHSO ₂ R, -CONHSO ₂ R]
(4) Carboxylic acid group (—CO ₂ H)
(5) Sulfonic acid group (-SO ₃ H)
(6) Phosphate group (-OPO ₃ H ₂ )
In the above (1) to (6), Ar represents a divalent aryl linking group which may have a substituent, and R represents a hydrogen atom or a hydrocarbon group which may have a substituent. ..

Among the resins having an acidic group selected from the above (1) to (6), a resin having an acid group with a pKa of 9 or less in its side chain is preferable, and a resin having a carboxy group in its side chain is more preferable.

<<Styrene-acrylonitrile copolymer>>
The styrene-acrylonitrile copolymer is not particularly limited as long as it is a resin containing at least a structural unit derived from styrene and a structural unit derived from acrylonitrile, but is preferably a resin having the above acidic group.
As the styrene-acrylonitrile copolymer, those known as those used for the image recording layer of the lithographic printing plate precursor can be used without particular limitation.
Examples of the acrylonitrile-derived copolymerization component include acrylonitrile and methacrylonitrile. Of these, acrylonitrile is preferable.
Examples of the styrene-derived copolymerization component include styrene, α-methylstyrene, p-hydroxystyrene, p-carboxystyrene and the like, and any of them can be preferably used.
The ratio of the acrylonitrile-derived copolymerization component to the styrene-derived copolymerization component is preferably 5% by mass to 50% by mass, and 10% by mass to 45% by mass of the total amount of the acrylonitrile-derived copolymerization component. % Is more preferable.

Further, in addition to the structural unit derived from acrylonitrile and the structural unit derived from styrene, other structural units may be further included. The other structural unit is not particularly specified as long as it is a structural unit derived from a compound having a copolymerizable C=C bond, but an acrylic compound is preferable, and an alkyl (meth)acrylate having 1 to 6 carbon atoms. And hydroxyalkyl (meth)acrylates having 1 to 6 carbon atoms.
Moreover, you may further contain the structural unit which has an acidic group.
Examples of the structural unit having an acidic group include structural units derived from a polymerizable compound such as (meth)acrylic acid and hydroxyphenyl(meth)acrylate. It may also contain a structural unit having an acidic group in the acrylic resin described later.
These other constitutional units can be contained in an amount of 1% by mass to 30% by mass based on the total mass of the resin.
The styrene-acrylonitrile copolymer can be synthesized by a known radical polymerization method such as emulsion polymerization, suspension polymerization, solution polymerization, or bulk polymerization, cationic polymerization method, anionic polymerization method, or the like. Further, the shape of the copolymer is not limited to a linear random copolymer, and may be a block copolymer or a graft copolymer.

In the present disclosure, the preferred styrene-acrylonitrile copolymer has a weight average molecular weight of 1,000 to 1,000,000, and more preferably 3,000 to 300,000.
The content of the styrene-acrylonitrile copolymer in the image recording layer is preferably in the range of 5% by mass to 80% by mass, and in the range of 10% by mass to 70% by mass, based on the total mass of the image recording layer. Is more preferable.

-acrylic resin-
The acrylic resin is not particularly limited as long as it is a resin containing at least a structural unit derived from an acrylic compound, but is preferably a resin having the above acidic group.
As the acrylic resin, those known as those used for the image recording layer of the lithographic printing plate precursor can be used without particular limitation.
As the acrylic resin, a polymer produced by polymerizing a monomer containing at least one ethylenically unsaturated monomer having an acidic group or a mixture thereof is preferably used.

As the ethylenically unsaturated monomer having an acidic group, (meth)acrylic acid or a monomer represented by the following formula is preferable. Among these monomers, (meth)acrylic acid is preferable, and methacrylic acid is more preferable.

The content of the ethylenically unsaturated monomer having an acidic group is preferably 1% by mass to 30% by mass, more preferably 5% by mass to 25% by mass, based on the total mass of the acrylic resin, since it has excellent developability. It is more preferably 10% by mass to 20% by mass.

Examples of monomers other than the ethylenically unsaturated monomer having an acidic group include alkyl (meth)acrylates, (meth)acrylic acid esters having an aliphatic hydroxyl group, (meth)acrylamides, vinyl esters, styrenes, N Examples include nitrogen atom-containing monomers such as vinylpyrrolidone and maleimides. Among these other monomers, preferably used are (meth)acrylic acid esters, (meth)acrylamides, maleimides, and (meth)acrylonitrile, and more preferably (meth)acrylamide and maleimide. It is a kind.

The maleimides are preferably N-substituted maleimides, and the N-substituted maleimides include, for example, N-methylmaleimide, N-ethylmaleimide, Nn-propylmaleimide, Ni-propylmaleimide, Nn-butyl. Examples thereof include maleimide, Nt-butylmaleimide, Nn-hexylmaleimide, N-cyclopentylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide and N-1-naphthylmaleimide. Among them, N-cyclohexylmaleimide and N-phenylmaleimide are preferable, and N-phenylmaleimide is more preferable. The N-substituted maleimides may be used alone or in combination of two or more.

The content of the structural unit derived from the N-substituted maleimide is preferably 50% by mass or less, more preferably 5% by mass to 50% by mass, further preferably 10% by mass to 40% by mass, based on the total mass of the acrylic resin. ..

When it contains a structural unit derived from (meth)acrylamide, the content of the structural unit is preferably 40% by mass or less, more preferably 1% by mass to 40% by mass, based on the total mass of the acrylic resin. More preferably, it is from 30% by mass to 30% by mass.

The weight average molecular weight of the acrylic resin is preferably 2,000 or more, more preferably 10,000 to 100,000, further preferably 30,000 to 60,000.

The content of the acrylic resin in the upper layer of the image recording layer is preferably 1% by mass to 60% by mass, more preferably 5% by mass to 50% by mass, based on the total mass of the upper layer of the image recording layer.

-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, R ¹ represents an aromatic ring group or a heteroaromatic ring group having at least one hydroxy group, R ² and R ³ are each independently a hydrogen atom, a halogen atom, a linear or branched group which may have a substituent, or a cyclic alkyl group, a linear or branched group 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 Formula EV-1, R ¹ represents an aromatic ring or a heteroaromatic ring having at least one hydroxy group, and the hydroxy group may be in the ortho, meta or para position with respect to the binding site with L. Good.
Preferable examples of the aromatic ring include phenyl group, benzyl group, tolyl group, o-, m-, p-xylyl group, naphthyl group, anthracenyl group, and phenanthrenyl group.
Preferred examples of the heteroaromatic ring include a furyl group, a pyridyl group, a pyrimidyl group, a pyrazoyl group and a thiophenyl group.
These aromatic rings or heteroaromatic rings may have a substituent other than a hydroxyl group, and examples of the substituent include an alkyl group such as a methyl group and an ethyl group, an alkoxy group such as a methoxy group and an ethoxy group, an aryloxy group. Group, thioalkyl group, thioaryl group, -SH, azo group such as azoalkyl group and azophenyl group, thioalkyl group, amino group, ethenyl group, alkenyl group, alkynyl group, cycloalkyl group, aryl group, heteroaryl group, or hetero group Examples thereof include alicyclic groups.
R ¹ is preferably a hydroxyphenyl group having a hydroxy group or a hydroxynaphthyl group, and more preferably a hydroxyphenyl group.
Examples of the hydroxyphenyl group include 2-, 3-, or 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 preferable examples of the substituent include alkoxy groups such as methoxy group and ethoxy group.

In Formula EV-1, L represents a divalent linking group, and 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 bond thereof It is preferred to represent the groups represented.
The alkylene group, the arylene group, or the heteroarylene group may have a substituent, and as the substituent, an alkyl group, a hydroxy group, an amino group, a monoalkylamino group, a dialkylamino group, an alkoxy group, and , Phosphonic acid groups or salts 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 More preferably,

In Formula EV-2, R ² and R ³ may each independently have a hydrogen atom, a halogen atom, a linear or branched alkyl group which may have a substituent, or a cyclic alkyl group which may have a substituent. It 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.
Examples of the alkyl group 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, 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, isohexenyl group. Group, cyclopentenyl group, cyclohexenyl group, and methylcyclohexenyl group.
A chlorine atom is mentioned as a halogen atom.
The aromatic ring preferably includes aryl groups such as phenyl group, benzyl group, tolyl group, o-, m-, p-xylyl group, naphthyl group, anthracenyl group and phenanthrenyl group.
Examples of the heteroaromatic ring include a furyl group, a pyridyl group, a pyrimidyl group, a pyrazoyl group, and a thiophenyl group.
R ² and R ³ each independently preferably represent a hydrogen atom, a chlorine atom or a methyl group, and more preferably a hydrogen atom.

Examples of the substituent on the alkyl group, alkenyl group, aromatic ring or heteroaromatic ring include methoxy group, alkoxy group such as ethoxy group, thioalkyl group, and —SH.
The aromatic ring or the 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 (provided that it is converted into a monomer unit) is preferably 10 mol% or more, and preferably 10 mol% to 55 mol% based on the total amount of the monomer unit 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 (provided that it is converted into a monomer unit) is preferably 15 mol% or more, and preferably 15 mol% to 60 mol% with respect to the total amount of the monomer unit 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 constitutional unit represented by the formula EV-1 and the constitutional unit represented by the formula EV-2 (however, converted as a monomer unit) is based on the total amount of the monomer unit 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, further preferably 10,000 to 300,000.

The content of the acetal resin in the upper layer of the image recording layer is preferably 1% by mass to 60% by mass, more preferably 5% by mass to 50% by mass, based on the total mass of the upper layer of the image recording layer.

-Resin having urea bond, urethane bond or amide bond in the main chain-
A resin having a urea bond, a urethane bond or an amide bond in its main chain means a polyurea polymer whose main chain is a urea bond, polyurethane a polymer whose main chain is a urethane bond, and an amide bond in its main chain. The polymer formed by is called polyamide. The resin having a urea bond, a urethane bond or an amide bond in the main chain may have at least one bond selected from the group consisting of a urea bond, a urethane bond and an amide bond in the main chain. You may have 2 or more types of these in the main chain.

As the structural unit contained in the resin having a urea bond, a urethane bond or an amide bond in the main chain, a structural unit formed by a polyvalent isocyanate compound, a polyvalent carboxylic acid salt compound (for example, a polyvalent carboxylic acid halide compound, or , A polycarboxylic acid ester compound) and the like.
These resins preferably have an acid group in the side chain.
The acid group is introduced into these resins as a constitutional unit formed by, for example, a polyhydric alcohol compound having an acid group or a polyvalent amine compound having an acid group. The polyhydric alcohol compound is preferably a diol compound. Further, the polyvalent amine compound is preferably a diamine compound.

From the viewpoint of developability, the pKa of the acid group is preferably 9 or less, more preferably 7 or less, and further preferably 5 or less.
The lower limit of pKa of the acid group is not particularly limited, but is preferably −5 or more, more preferably 1 or more. These pKa can be calculated in the same manner as the above-mentioned pKa.

The acid group having a pKa of 9 or less is not particularly limited, but includes a sulfonamide group (-SO ₂ -NH- or -SO ₂ -NRsH, Rs is a hydrogen atom or a known substituent), a phenolic hydroxyl group, a carboxy group, and a sulfo group. Group, a phosphoric acid group, a phosphonic acid group, a sulfuric acid group, and the like, and a carboxy group is preferable from the viewpoints of printing durability, abrasion resistance, and developability.

Further, a urea bond, a urethane bond or an amide bond as the other structural unit contained in the resin having a main chain, a polyhydric alcohol compound other than a polyhydric alcohol compound having an acid group or a basic group, and, And may further have a structural unit formed by at least one compound selected from the group consisting of polyvalent amine compounds other than the above-mentioned polyvalent amine compound having an acid group or a base group. ..
The polyisocyanate compound is preferably a diisocyanate compound.
The polycarboxylic acid salt compound is preferably a dicarboxylic acid salt compound.
As the polyhydric alcohol compound, a diol compound is preferable.
A diamine compound is preferable as the polyvalent amine compound.

For example, a resin having a urea bond in the main chain (polyurea) is obtained by reacting the polyvalent isocyanate compound, and optionally the other polyvalent alcohol compound and the other polyvalent amine compound. Be done.
Further, for example, a resin (polyurethane) having a urethane bond in its main chain is obtained by reacting the polyvalent isocyanate compound, the polyhydric alcohol compound, and optionally the polyvalent amine compound.
In addition, for example, a resin having an amide bond in the main chain by reacting the polyvalent carboxylate compound, and optionally the other polyhydric alcohol compound, and the other polyvalent amine compound. (Polyamide) is obtained.
These reactions can be performed under known conditions.

Examples of polyvalent isocyanate compounds include 1,3-bis(isocyanatomethyl)cyclohexane, isophorone diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, 1,3-cyclopentane diisocyanate, 9H- Fluorene-2,7-diisocyanate, 9H-fluoren-9-one-2,7-diisocyanate, 4,4'-diphenylmethane diisocyanate, 1,3-phenylene diisocyanate, tolylene-2,4-diisocyanate , Tolylene-2,6-diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, 2,2-bis(4-isocyanatophenyl)hexafluoropropane, 1,5-diisocyanatonaphthalene, etc. Be done.
The content of the constituent unit formed by the polyvalent isocyanate compound is preferably 10% by mass or more and 60% by mass or less based on the total mass of the resin having a urea bond, a urethane bond or an amide bond in the main chain, 20 It is more preferable that the content is at least 50% by mass.

Examples of the polyvalent carboxylic acid salt compound include polyvalent carboxylic acid halide compounds (for example, polyvalent carboxylic acid chloride compounds), polyvalent carboxylic acid ester compounds, and the like. Examples thereof include CL-1 to CL-10 below. Is mentioned.
The content of the constituent unit formed by the polyvalent carboxylate compound is preferably 10% by mass or more and 60% by mass or less based on the total mass of the resin having a urea bond, a urethane bond or an amide bond in the main chain. It is more preferable that the content is 20 mass% or more and 40 mass% or less.

Examples of the polyhydric alcohol compound include polyhydric alcohol compounds used for forming a constitutional unit having an alkyleneoxy group described later, and examples thereof include ethylene glycol, propylene glycol, 1,4-butanediol, and 1,5-pentane. Diol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, neopentyl glycol, polyethylene glycol, polypropylene glycol, polytetramethylene Examples thereof include glycol, 1,4-cyclohexanedimethanol and 3-methyl-1,5-pentanediol.
The content of the constituent unit formed by the polyhydric alcohol compound is preferably 0% by mass or more and 40% by mass or less with respect to the total mass of the resin having a urea bond, a urethane bond or an amide bond in the main chain. It is more preferable that the content is 30% by mass or more and 30% by mass or less.

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, 1,7-diaminoheptane, N,N-bis(3-aminopropyl)methylamine, 1,3-diamino-2-propanol, diethylene glycol bis(3-aminopropyl)ether, m-xylylenediamine, tetraethylenepenta Min, 1,3-bis(aminomethyl)cyclohexane, benzoguanamine, 2,4-diamino-1,3,5-triazine, 2,4-diamino-6-methyl-1,3,5-triazine, 6-chloro -2,4-diaminopyrimidine, 2-chloro-4,6-diamino-1,3,5-triazine and the like can be mentioned.
The content of the constituent unit formed by the polyvalent amine compound is preferably 0% by mass or more and 40% by mass or less based on the total mass of the resin having a urea bond, a urethane bond or an amide bond in the main chain. It is more preferable that the content is 20% by mass or more.

The resin having a urea bond, a urethane bond or an amide bond in the main chain preferably further has a constituent unit having an alkyleneoxy group in the main chain from the viewpoint of further improving printing durability.
The alkyleneoxy group is preferably an alkyleneoxy group having 2 to 10 carbon atoms, more preferably an alkyleneoxy group having 2 to 8 carbon atoms, further preferably an alkyleneoxy group having 2 to 4 carbon atoms, an ethyleneoxy group, or , A propyleneoxy group is particularly preferable.
The alkyleneoxy group may be a polyalkyleneoxy group.
As the polyalkyleneoxy group, a polyalkyleneoxy group having a repeating number of 2 to 50 is preferable, a polyalkyleneoxy group having a repeating number of 2 to 40 is more preferable, and a polyalkyleneoxy group having a repeating number of 2 to 30 is further preferable.
The preferred carbon number of the constituent unit of the polyalkyleneoxy group is the same as the preferred carbon number of the alkyleneoxy group.
The constituent unit having an alkyleneoxy group is introduced, for example, by using a polyalkylene glycol compound (eg, polyethylene glycol or polypropylene glycol) as the polyhydric alcohol compound.
The content of the structural unit having an alkyleneoxy group is preferably 0.1% by mass or more and 40% by mass or less with respect to the total mass of the resin having a urea bond, a urethane bond or an amide bond in its main chain, and 1% by mass. % Or more and 30% by mass or less is more preferable, and 5% by mass or more and 20% by mass or less is more preferable.

The weight average molecular weight of the resin having a urea bond, a urethane bond or an amide bond in its main chain is preferably 2,000 or more, more preferably 10,000 to 100,000, further preferably 10,000 to 60,000.

The content of the resin having a urea bond, urethane bond or amide bond in the main chain in the upper layer of the image recording layer is preferably from 1% by mass to 60% by mass, and preferably from 5% by mass to the total mass of the upper layer of the image recording layer. 50 mass% is more preferable.

[Acid generator, acid multiplying agent, and other additives]
The upper layer of the image recording layer may contain an acid generator, an acid multiplying agent, other additives and the like.
Other additives include a development accelerator, a surfactant, a printout agent, a coloring agent, a plasticizer, a wax agent and the like.
The acid generator used in the upper layer of the image recording layer, a preferred embodiment of the acid proliferating agent and other additives, the acid generator used in the lower layer of the image recording layer, a preferred embodiment of the acid proliferating agent and other additives, respectively. It is the same.

[Layer structure of image recording layer]
The lithographic printing plate precursor according to the present disclosure has a support, an image recording layer lower layer, and an image recording layer upper layer in this order.
In addition, all layers of the image recording layer in the present disclosure do not need to have infrared sensitivity, and may be a layer that can form an image-like plate by development as the entire image recording layer.
Further, the lithographic printing plate precursor according to the present disclosure further has, as an image recording layer, one or more layers other than the image recording layer lower layer and the image recording layer upper layer (hereinafter, also referred to as “other layer”). You may have. Examples of the other layer include known image recording layers. The position of the other layer is not particularly limited and may be between the support and the image recording layer lower layer, between the image recording layer lower layer and the image recording layer upper layer, or the image recording layer upper layer. May be above.

The lower layer of the image recording layer and the upper layer of the image recording layer are preferably formed by separating the two layers.
As a method for forming the two layers separately, for example, a method of utilizing a difference in solvent solubility between a component contained in the lower layer and a component contained in the upper layer, or a method of applying a solvent rapidly after coating the upper layer And the like. It is preferable to use the latter method in combination, because the layers can be more favorably separated.
Hereinafter, these methods will be described in detail, but the method of separating and applying the two layers is not limited thereto.

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

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

The lower layer of the image recording layer is preferably thicker than the upper layer of the image recording layer, from the viewpoints of developability with time and printing durability with time. That is, the amount per unit area of the lower layer of the image recording layer is preferably larger than the amount per unit area of the upper layer of the image recording layer from the viewpoints of developability over time and printing durability over time.

The amount per unit area of the image recording layer lower layer in the lithographic printing plate precursor according to the present disclosure is not particularly limited, but is preferably in the range of 0.5 g/m ² to 4.0 g/m ² . It is more preferably in the range of 6 g/m ² to 2.5 g/m ² . When it is 0.5 g/m ² or more, printing durability is excellent, and when it is 4.0 g/m ² or less, image reproducibility and sensitivity are excellent.
The amount per unit area of the image recording layer upper layer is not particularly ^limited, it is preferably in the range of ^{0.05g / m 2 ~ 1.0g / m} 2, 0.08g / m 2 ~ 0. The range of 7 g/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 coating amount per unit area of the entire image recording layer is not particularly limited, but is preferably in the range of 0.6 g/m ² to 4.0 g/m ² , and 0.7 g/m ² to 2. It is more preferably in the range of 5 g/m ² . When it is 0.6 g/m ² or more, printing durability is excellent, and when it is 4.0 g/m ² or less, image reproducibility and sensitivity are excellent.

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

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

Aluminum which is particularly suitable in the present disclosure is pure aluminum, but completely pure aluminum is difficult to produce due to refining technology, and thus may contain slightly different elements.
As described above, the composition of the aluminum plate applied to the present disclosure is not specified, and an aluminum plate that is a publicly known and conventionally used 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.

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

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

<Backcoat layer>
A back coat layer is provided on the back surface of the support of the lithographic printing plate precursor according to the present disclosure, if necessary. The back coat layer is composed of an organic polymer compound described in JP-A-5-45885 and a metal oxide obtained by hydrolyzing and polycondensing an organic or inorganic metal compound described in JP-A-6-35174. A coating layer is preferably used. Of 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. It is particularly preferable that the coating layer of metal oxide obtained therefrom is excellent in developing resistance.

(Method of preparing lithographic printing plate)
The method for producing a lithographic printing plate according to the present disclosure includes an exposure step of imagewise exposing the lithographic printing plate precursor according to the present disclosure, and developing the exposed lithographic printing plate precursor with a developer having a pH of 10.0 or less. The developing process is included in this order.
Hereinafter, each step of the manufacturing 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 includes an exposure step of imagewise exposing the lithographic printing plate precursor according to the present disclosure.
As a light source of actinic rays used for image exposure of the lithographic printing plate precursor according to the present disclosure, a light source having an emission wavelength in the near infrared to infrared region is preferable, and a solid laser and a semiconductor laser are more preferable. Among them, in the present disclosure, it is particularly preferable to perform image exposure with a solid-state laser or 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 within 20 μsec.
The energy applied to the lithographic printing plate precursor is preferably 10 mJ/cm ² to 300 mJ/cm ² . Within the above range, the solubility of the image recording layer in an alkaline aqueous solution is sufficiently improved, laser ablation is suppressed, and image damage can be prevented.

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

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

<Developing process>
The method for producing a lithographic printing plate according to the present disclosure includes a developing step of developing the exposed lithographic printing plate precursor using a developing solution.
The developing solution used in the developing step is not particularly limited, but the developing solution is preferably an aqueous solution.
Further, in the method for producing a lithographic printing plate according to the present disclosure, for example, development may be performed using a developing solution having a pH of more than 10.0. For example, development can be performed using a known developing solution such as the developing solutions described in paragraphs 0270 to 0292 of JP-A-2003-1956.

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

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

The developing solution used in the developing step is not particularly limited as long as it can be developed, but is preferably a developing solution having a pH of 10.0 or less, more preferably a developing solution having a pH of 8.0 to 10.0. It is particularly preferable that the developer has a pH of 9.0 to pH 9.9.
In such a relatively low pH developer, compared with a conventionally used high pH developer having a pH of about 12, for example, a decrease in pH due to dissolution of CO _{2 in} the atmosphere is suppressed. Easy to be affected. That is, it can be said that the low pH is excellent in stability during use or storage of the developer.
In the low pH developer, the decrease in the pH of the developer is suppressed as described above, so that the deterioration of the developability, the generation of development residue, etc. 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. A carbonate buffer system is particularly preferable as the buffer solution.
In the present disclosure, the carbonate buffer system refers to a buffer solution containing carbonate ion and hydrogen carbonate ion as a buffering agent.
In order to allow the carbonate ion and the hydrogen carbonate ion to exist in the developing solution, a carbonate and a hydrogen carbonate may be added to the developing solution, or the carbonate may be added by adding the carbonate or the hydrogen carbonate and then adjusting the pH. Ions and hydrogen carbonate ions may be generated. The carbonate and 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 further preferably 1% by mass to 5% by mass, based on the total mass of the developer. % Is particularly preferred. When the total amount is 0.3% by mass or more, developability and processing ability are not deteriorated, and when the total amount is 20% by mass or less, it becomes difficult to generate a precipitate or a crystal, and further, when the waste liquid of the developing solution is treated or during neutralization. It does not easily gel and does not interfere with waste liquid treatment.

Further, for the purpose of finely adjusting the alkali concentration and assisting the dissolution of the image recording layer in the non-image area, other alkali agents, for example, organic alkali agents may be supplementarily used. As the organic alkaline agent, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, triisopropylamine, n-butylamine, monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, Diisopropanolamine, ethyleneimine, ethylenediamine, pyridine, tetramethylammonium hydroxide and the like can be mentioned. 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 chelate compound, a defoaming agent, an organic acid, an organic solvent, an inorganic acid, an inorganic salt and the like. However, when the water-soluble polymer compound is added, the plate surface tends to become sticky, especially when the developing solution is fatigued, so it is preferable not to add it.

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

As the preservative, the preservative described in paragraph 0142 of JP2013-134341A can be preferably used. It is preferable to use two or more kinds of preservatives together so that they are effective against various molds and sterilizations. The addition amount of the preservative is an amount that exerts a stable effect on bacteria, molds, yeasts, etc. and varies depending on the types of bacteria, molds, yeasts, but it is 0 for 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. The chelating agent is selected so that it stably exists in the developer composition and does not impair the printability. The addition amount is preferably 0.001% by mass to 1.0% by mass with respect to the total mass of the developer.

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

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

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

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

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

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

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

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

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

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

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

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

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

<Synthesis of Polymer A>
SA-1 to SA-19 were synthesized by the following method.

[Synthesis of Monomer Forming Structural Unit S-1]
A 200 mL three-necked flask was charged with 15 g of sulfamethizole (manufactured by Tokyo Chemical Industry Co., Ltd.), 2.22 g of sodium hydroxide, 100 g of acetone, and 100 g of pure water, and stirred with an ice bath. Methacrylic acid chloride: 6.09 g (manufactured by Tokyo Chemical Industry Co., Ltd.) was added dropwise thereto, and after completion of the dropwise addition, the mixture was stirred at room temperature for 2 hours. The content was poured into 1 L of pure water and adjusted to pH 2 with 1N (1 mol/L) concentrated hydrochloric acid. The obtained solid was collected by filtration and washed with water to obtain a monomer S-1.

[Synthesis of Monomers S-2 to S-11 Forming Structural Units S-2 to S-11]
In the synthesis of the monomer S-1, each was synthesized by the same method except that the above sulfamethizole was changed to the corresponding amine.

[Synthesis of SA-1]
Dimethyl sulfoxide: 16.7 g was placed in a three-necked flask and stirred under a nitrogen stream at 85°C for 30 minutes. Monomer forming the above S-1 there: 8.46 g, methyl methacrylate (M-1): 1.54 g, V-601 (trade name, 2,2'-azobis(isobutyronitrile), FUJIFILM A mixed solution of 0.094 g of Wako Pure Chemical Industries, Ltd. and dimethyl sulfoxide: 18.0 g was added dropwise over 2 hours. After the dropwise addition was completed, the mixture was further reacted at 85° C. for 1 hour 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 SA-1.

[Synthesis of SA-2 to SA-13 and SA-15 to SA-26]
Synthesis was carried out by the same method as SA-1, except that the monomers used and the amounts used were changed appropriately.

[Synthesis of Monomer S-12 Forming Structural Unit S-12]
As shown below, 3-hydroxy-γ-butyrolactone was reacted with the following amine compound having a sulfonamide bond to synthesize a monomer forming S-12.

[Synthesis of Monomer S-13 Forming Structural Unit S-13]
A three-necked flask was charged with 10 g of sulfamethizole (manufactured by Tokyo Kasei Kogyo Co., Ltd.) and 100 g of acetone, and the mixture was stirred in an ice bath. Karens MOI: 30 g (manufactured by Showa Denko KK) was added dropwise thereto, and after completion of the dropwise addition, the mixture was stirred at room temperature for 2 hours. The content was poured into 1 L of hexane, the obtained solid was collected by filtration, and air-dried to obtain a monomer S-13.

[Synthesis of SA-14]
Into a three-necked flask, 30.0 g of methyl ethyl ketone, 5.90 g of a monomer forming S-12 and MDI (diphenylmethane diisocyanate, manufactured by Tokyo Chemical Industry Co., Ltd.): 4.10 g were placed, and the mixture was placed at 65° C. Heated. Neostan U-600 (trade name, bismuth octylate, manufactured by Nitto Kasei Co., Ltd.): 0.040 g was put therein, reacted at 65° C. for 3 hours, and then 5.0 g of methanol was added, and further for 30 minutes. It was stirred. Well-stirred water: When poured into 500 g, a solid was precipitated. The precipitated solid was filtered, washed with water, and dried under reduced pressure to obtain SA-14.

[Synthesis of Monomer M-7 Forming Structural Unit M-7]
4-aminophenol: 4.0 g (manufactured by Tokyo Chemical Industry Co., Ltd.) and acetone: 100 g were placed in a three-necked flask and stirred with an ice bath. Karens MOI: 30 g (manufactured by Showa Denko KK) was added dropwise thereto, and after completion of the dropwise addition, the mixture was stirred at room temperature for 2 hours. The content was poured into 1 L of hexane, the obtained solid was collected by filtration, and air-dried to obtain a monomer M-7.

[Synthesis of SA-27]
Novolak resin (PR-54046, manufactured by Sumitomo Bakelite Co., Ltd.): 20.0 g, isophorone diisocyanate (manufactured by Tokyo Chemical Industry Co., Ltd.): 36.4 g, and N,N-dimethylacetamide: 100.0 g in a three-necked flask. And stirred at 75° C. for 3 hours. A mixed solution of 44.3 g of sulfamethizole (manufactured by Tokyo Chemical Industry Co., Ltd.) and 50.0 g of N,N-dimethylacetamide was added dropwise thereto over 1 hour. After the dropping was completed, the reaction was further performed at 75° C. for 1 hour, and then the mixture was poured into well-stirred water: 2,500 g to precipitate a solid. The precipitated solid was filtered, washed with water and dried under reduced pressure to obtain SA-27.

<Synthesis of Polymer B>
Polymer B P-1 to P-3 were synthesized by the following method.

[Synthesis of P-1]
1-Methoxy-2-propanol (48.0 g) and acetic acid (1.58 g) were placed in a three-necked flask, and the mixture was stirred at 75° C. for 30 minutes under a nitrogen stream. Monomer A1-1:7.44 g, MMA (methyl methacrylate): 1.28 g, Monomer B1-16.28 g, V-601 (trade name, 2,2'-azobis(isobutyronitrile), Fuji Film) A mixed liquid of 0.34 g of Wako Pure Chemical Industries, Ltd. 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 P-1.

[Synthesis of P-2]
Synthesis was performed in the same manner as in P-1, except that the monomers used were changed appropriately.

[Synthesis of P-3]
Novolak resin (m-cresol/p-cresol/phenol=3/2/5 (molar ratio), weight average molecular weight 8,000): 20.0 g, sodium hydroxide: 4.17 g, tetrahydrofuran in a three-necked flask. (THF): 30 mL was added, and the mixture was stirred at room temperature for 30 minutes. A mixed solution of chloroacetic acid: 8.21 g and THF: 30 mL was added dropwise thereto over 1 hour. Then, the mixture was reacted under reflux condition for 5 hours, allowed to cool to room temperature, poured into 1 L of 1N (mol/L)-HCl aqueous solution, and the obtained solid (P-3) was collected by filtration. The acid value of the obtained solid was 2.0 meq/g.

(Examples 1-37 and Comparative Examples 1-4)
<Preparation of support>
A support was produced 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>
An undercoat layer coating solution 1 shown below was applied onto the support and dried at 80° C. for 15 seconds to form an undercoat layer. The coating amount after drying was 15 mg/m ² .

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

In the above chemical formula, the subscripts in parentheses indicate the content (mass %) of each structural unit. Et represents an ethyl group.

<Formation of Image Recording Layer Lower Layer and Image Recording Layer Upper Layer>
The support having an undercoat layer thus obtained was coated with a composition for forming an image recording layer underlayer having the following composition using a wire bar and then dried in a drying oven at 150° C. for 40 seconds to give a coating amount of 1.0 g. /M ² so that the lower layer of the image recording layer was provided. After the lower layer of the image recording layer was provided, the composition for forming the upper layer of the image recording layer having the following composition was applied with a wire bar to provide the upper layer of the image recording layer. After coating, it was dried at 150° C. for 40 seconds to obtain a lithographic printing plate precursor in which the coating amount of the lower layer of the image recording layer and the upper layer of the image recording layer was 1.2 g/m ² .
Further, in Example 35, the amount of the polymer A used was changed to 4.5 parts, the amount of the lower layer of the image recording layer was 1.2 g/m ^2, and the lower layer of the image recording layer and the upper layer of the image recording layer were changed. The image recording layer lower layer and the image recording layer upper layer were formed in the same manner as in Example 1 except that the combined coating amount was 2.2 g/m ² .
Further, in Example 36, the amount of the polymer B used was changed to 1.0 part, and the amount of the image recording layer upper layer formed was 0.3 g/m ² , and the image recording layer lower layer and the image recording layer upper layer were formed. The image recording layer lower layer and the image recording layer upper layer were formed in the same manner as in Example 1 except that the combined coating amount was 0.5 g/m ² .

-Composition for forming image recording layer upper layer-
Polymer B (P-1 to P-3) shown in Tables 1 to 3: 0.58 parts unless otherwise specified in Table 1 or Table 2 Infrared absorber shown in Tables 1 to 3: 0.045 parts Megafac (registered trademark) F-780 (fluorine-based surfactant, manufactured by DIC Corporation): 0.03 part Acetic acid: 12.0 parts Methyl ethyl ketone: 13.0 parts 1-Methoxy-2-propanol: 30.0 Parts 1-(4-methylbenzyl)-1-phenylpiperidinium 5-benzoyl-4-hydroxy-2-methoxybenzenesulfonate: 0.01 parts

-Composition for forming lower layer of image recording layer-
Polymer A described in Tables 1 to 3 (SA-1 to SA-19, SA-C1 or SA-C2): 3.5 parts unless otherwise specified in Tables 1 to 3, described in Tables 1 to 3 Infrared absorber: 0.045 parts Megafac (registered trademark) F-780: 0.07 parts Methyl ethyl ketone: 30.0 parts 1-Methoxy-2-propanol: 15.0 parts γ-butyrolactone: 15.0 parts 4, 4'-bishydroxyphenyl sulfone: 0.3 part Tetrahydrophthalic acid: 0.4 part p-Toluenesulfonic acid: 0.02 part 3-Methoxy-4-diazodiphenylamine hexafluorophosphate: 0.06 part Ethyl violet pair Ion changed to 6-hydroxynaphthalene sulfonic acid: 0.15 parts

The following evaluation was performed using the obtained planographic printing plate precursor. The results are shown in Tables 1 to 3.

<Aging developability>
After preparing the planographic printing plate precursor, it was left at 45° C. for 24 hours. The lithographic printing plate precursor after being left standing was image-wise drawn with a Trendsetter VX manufactured by Creo at a beam intensity of 9 W and a drum rotation speed of 150 rpm (revolutions per minute). Then, it was immersed in a developing bath charged with the developer 1 having the following composition, 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 with a Macbeth densitometer became equivalent to the image density of the support was defined as the non-image area development time, and the measured values (seconds) are shown in the table. When 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 "undevelopable". The shorter the non-image area development time, the better the developability.

[Developer 1: pH 9.7]
Water: 8,964 parts Sodium carbonate: 150 parts Sodium hydrogen carbonate: 150 parts Newcol B4SN (trade name, polyoxyethylene naphthyl ether sulfate, the following compound, manufactured by Nippon Emulsifier Co., Ltd.): 150 parts Ethylenediaminetetraacetate 4 sodium Salt: 80 parts

<Ablation suppression property>
A transparent polyethylene terephthalate film (manufactured by FUJIFILM Co., Ltd.) having a thickness of 0.1 mm was brought into close contact with the surface of the obtained lithographic printing plate precursor, and the entire surface was exposed under the same conditions as in the evaluation of the developability. did.
After the exposure, the polyethylene terephthalate film was removed and visually observed to observe the degree of surface contamination. The case where no stain was observed was A, the case where a little stain was observed was B, and the case where it was stained to the extent that it could not be seen through the other side of the film was judged as C.
It can be said that the less the stain is, the more excellent the abrasion resistance is. Therefore, the evaluation is preferably A or B, and more preferably A.

The following evaluations were made using the evaluations after the planographic printing plate precursor was prepared and left at 45° C. for 24 hours.

<Durability over time>
The lithographic printing plate precursor after being left standing was image-wise drawn with a Trendsetter manufactured by Creo at a beam intensity of 9 W and a drum rotation speed of 150 rpm (revolutions per minute).
Then, using a PS processor LP940H manufactured by Fuji Film Co., Ltd. charged with the developing solution 1, development was performed at a developing temperature of 30° C. and a developing time of the non-image area developing time+2 seconds. This was continuously printed using a printing machine Lithrone manufactured by Komori Corporation. As the ink, as a model of low-grade material, Tokushu Ink Co., Ltd. special ink ink containing calcium carbonate was used. At this time, the printing durability was evaluated by visually observing how many sheets can be printed while maintaining a sufficient ink density. The number of sheets in Comparative Example 2 was set to 100, and relative evaluation was performed by the number of sheets.

<Prevention of developmental debris over time>
Similar to the evaluation of the developability, the lithographic printing plate precursor exposed after the above-mentioned standing was used to evaluate the suppressive property of the development dust according to the following procedures (1) to (3).
(1) Two exposure plates cut into 18 cm×10 cm were immersed in 150 mL of the developer 1 placed in a vat to dissolve them.
(2) The developing solution in which the exposure plate was dissolved was transferred to a resin container and allowed to stand overnight.
(3) The state of dregs of the stationary developer was visually evaluated according to the following evaluation criteria.
If the evaluation is A or B, it can be said that the development dust suppressing property is excellent, and if the evaluation is A, the development dust suppressing property is further excellent.
〔Evaluation criteria〕
A: No dust was seen from the time of development.
B: Dust was seen at the time of development, but was not seen after standing overnight.
C: Scrap remained even after standing overnight.

<Holdability of image portion over time>
The lithographic printing plate precursor after being left standing is immersed in a developing bath containing the developing solution 1 without being exposed to light, and the image density of the image recording layer measured by a Macbeth densitometer at a developing temperature of 30° C. is before immersion. The immersion time at which the image density of the image recording layer was lower than that of the image recording layer by 3% was defined as the image part holding time (second). The longer the image area development time, the better the image area retention.

The columns of the constitutional unit ratio of the polymer A in Examples 1 to 52 and Comparative Examples 1, 2 and 4 are (amount ratio of constitutional units having a —SO ₂ —NH— structure)/(amount of other constitutional units). Ratio). In the column of the constitutional unit ratio of the polymer A in Comparative Example 3, the constitutional unit ratios of SA-C2 shown below are listed in order from the constitutional unit on the left side.
In Comparative Example 3 in Table 1, SA-C2 shown below was used as the polymer A in the upper layer of the image recording layer.
The amounts of the polymer B and the other polymers used in Tables 1 to 3 are the mass proportions of the polymer B and the other polymers in the upper layer of the image recording layer in a total amount of 100 mass %.
In Tables 1 to 3, "(lower layer pKa)-(upper layer pKa)" means "the above-mentioned -SO ₂ -NH- structure pKa in polymer A contained in the lower layer of the image recording layer"-"upper layer of the image recording layer". Represents the pKa) of the acid group in polymer B contained in.
In Table 1, "-" in the column for evaluation of the development debris suppression property over time and the retention property of the image area over time of Comparative Example 2 indicates that development could not be sufficiently performed and evaluation was not possible.
Further, details of the abbreviations described in Tables 1 to 3 other than the above are shown below.

S-1 to S-14: Structural units shown below

U-1: Structural unit shown below

SA-C1: Polymer having the constitutional units shown below in the mass ratio shown in Table 1, was synthesized by the same method as the method described in the example of WO 2014/003134.

M-1: Structural unit derived from methyl methacrylate (structural unit shown below)
M-2: 2-ethylhexyl methacrylate (EHMA)-derived constitutional unit (constitutional unit shown below)
M-3: Structural unit derived from benzyl methacrylate (BnMA) (structural unit shown below)
M-4: Structural unit derived from 2-hydroxyethyl methacrylate (the structural unit shown below)
M-5: Structural unit derived from N-(4-hydroxyphenyl)methacrylamide (manufactured by Tokyo Chemical Industry Co., Ltd.) (structural unit shown below)
M-6: 2-hydroxy-5-methacrylamidobenzoic acid (manufactured by Aldrich)-derived constitutional unit (constitutional unit shown below)
M-7: Structural unit derived from a 1/1 (molar ratio) reaction product of Karens MOI (2-isocyanatoethyl methacrylate, Showa Denko KK) and 4-aminophenol (Tokyo Kasei KK) (Structural units shown below)
M-8: 4-hydroxyphenylmaleimide (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.) derived constitutional unit (constitutional unit shown below)
M-9: N-(4-sulfamoylphenyl)methacrylamide (Fujifilm Wako Pure Chemical Industries, Ltd.)-derived constitutional unit (constitutional unit shown below)
M-10: structural unit derived from FX-AO-MA (manufactured by Nippon Shokubai Co., Ltd.) (structural unit shown below)

IR-1 to IR-3: Infrared absorber, the following compounds

IR-4: IR 783 (manufactured by Tokyo Chemical Industry Co., Ltd., the following compound)
IR-5: Compound described in Paragraph 0083 of Japanese Patent No. 6189838 (the following compound)
IR-6: 2,4-bis[4-(diethylamino)-2-hydroxyphenyl] squaraine (Tokyo Chemical Industry Co., Ltd., the following compound)
IR-7: 2,4-bis[8-hydroxy-1,1,7,7-tetramethyljulolidin-9-yl] squaraine (Tokyo Chemical Industry Co., Ltd., the following compound)
IR-8: NK1841 (Tokyo Chemical Industry Co., Ltd., the following compound)
IR-9: IR-820 (manufactured by Aldrich, compound below)
IR-10: Indomonocarbocyanine sodium (manufactured by Tokyo Chemical Industry Co., Ltd., the following compound)

P-4: novolac resin (m-cresol/p-cresol/phenol=3/2/5 (molar ratio), weight average molecular weight 8,000, Sumitomo Bakelite Co., Ltd., PR-55618, pKa=10)

From the results shown in Tables 1 to 3, the lithographic printing plate precursors of Examples 1 to 52, which are lithographic printing plate precursors according to the present disclosure, were compared with the lithographic printing plate precursors of Comparative Examples 1 to 4 after storage with time. Even if it exists, it has excellent developability and printing durability.
Further, it can be seen that the lithographic printing plate precursors of Examples 1 to 52, which are lithographic printing plate precursors according to the present disclosure, are excellent in ablation suppression property, temporal image area retention property, and temporal development debris suppression property.

The disclosure of Japanese Patent Application No. 2018-221168 filed on November 27, 2018 and the disclosure of Japanese Patent Application No. 2019-034219 filed on February 27, 2019 are in their entirety. Incorporated herein by reference.
All documents, patent applications, and technical standards mentioned in this specification are to the same extent as if each individual document, patent application, and technical standard were specifically and individually noted to be incorporated by reference. Are incorporated herein by reference.

Claims (13)

Having a support, an image recording layer lower layer, and an image recording layer upper layer in this order,
The image recording layer lower layer contains a polymer A having a structural unit having a —SO ₂ —NH— structure with a pKa of less than 10,
The image recording layer upper layer contains a polymer B having a structural unit having an acid group having a pKa of less than 10, and an infrared absorber,
The content of the polymer B is 30% by mass or more based on the total mass of the polymer contained in the upper layer of the image recording layer,
Original planographic printing plate. The lithographic printing plate precursor according to claim 1, wherein the —SO ₂ —NH— structure in the polymer A is a structure represented by any one of the following formulas 1 to 3.

In Formulas 1 to 3, Ar ₁ represents an arylene group, Ar ₂ represents an aryl group or a heteroaryl group, R ₁ represents a monovalent organic group, and * represents a bond with another structure. Represents a part. The lithographic printing plate precursor according to claim 2, wherein the —SO ₂ —NH— structure in the polymer A is a structure represented by the formula 1. Wherein Ar ₁ is a group having a phenylene structure, wherein Ar ₂ is a heteroaryl group, a lithographic printing plate precursor as claimed in claim 3 in Formula 1. Wherein Ar ₁ in the formula 1 is a group having a phenylene structure, wherein Ar ₂ is a furan ring, isothiazoline ring, isoxazoline ring, oxadiazoline ring, oxa triazine ring, an oxazoline ring, a pyrazine ring, a pyridazine ring, pyridine A heteroaryl group having at least one heteroaromatic ring structure selected from the group consisting of a ring, a pyrimidine ring, a tetrazine ring, a thiadiazole ring, a thiatriazole ring, a thiazole ring, a thiophene ring, and a triazine ring. The lithographic printing plate precursor according to claim 4. Wherein Ar ₁ in the formula 1 is a group having a phenylene structure, wherein Ar ₂ is isoxazoline ring, a pyridazine ring, a pyrimidine ring, at least one heteroaromatic ring selected from the group consisting of thiadiazole ring and a thiazole ring The lithographic printing plate precursor as claimed in any one of claims 3 to 5, which is a heteroaryl group having a structure. The lithographic printing plate precursor as claimed in any one of claims 1 to 6, wherein the acid group in the polymer B is a carboxy group. The lithographic printing plate precursor according to any one of claims 1 to 7, wherein the polymer B in the upper layer of the image recording layer further has a structural unit having a basic group. The lithographic printing plate precursor according to claim 8, wherein the basic group in the polymer B is a tertiary amino group. 10. The lithographic printing plate precursor as claimed in claim 1, wherein the polymer A has a pKa of the —SO ₂ —NH— structure of 3.5 or more and 8.5 or less. The lithographic printing plate precursor according to any one of claims 1 to 10, wherein the pKa of the acid group in the polymer B is 3.0 or more and 7.0 or less. An exposure step of exposing the lithographic printing plate precursor according to any one of claims 1 to 11 to an image;
A method for producing a lithographic printing plate, which comprises, in this order, a developing step of developing the exposed lithographic printing plate precursor using a developer. The method for producing a lithographic printing plate according to claim 12, wherein the pH of the developer is 10.0 or less.