JP4832345B2 - Planographic printing plate precursor and planographic printing method - Google Patents

Description

  The present invention relates to a lithographic printing plate precursor and a lithographic printing method using the same. Specifically, based on a digital signal from a computer or the like, for example, a lithographic printing plate precursor capable of direct plate making that can be directly made by scanning a laser having a wavelength of 300 to 1200 nm, and the lithographic printing plate precursor The present invention relates to a lithographic printing method for directly developing and printing on a printing machine without going through a development processing step.

In general, a lithographic printing plate comprises an oleophilic image area that receives ink in the printing process and a hydrophilic non-image area that receives dampening water. Lithographic printing utilizes the property that water and oil-based inks repel each other, so that the oleophilic image area of the lithographic printing plate is the ink receiving area, and the hydrophilic non-image area is dampened with the water receiving area (ink non-receiving area). In this method, a difference in ink adhesion is caused on the surface of the lithographic printing plate, and after ink is applied only to the image area, the ink is transferred to a printing medium such as paper and printed.
In order to produce this lithographic printing plate, conventionally, a lithographic printing plate precursor (PS plate) in which an oleophilic photosensitive resin layer (image recording layer) is provided on a hydrophilic support has been widely used. Usually, after exposing a lithographic printing plate precursor through an original image such as a lithographic film, the image recording layer to be an image portion is left, and other unnecessary image recording layers are washed with an alkaline developer or an organic solvent. Plate making is performed by a method of exposing the surface of the hydrophilic support by dissolving and removing to obtain a lithographic printing plate.

  In the conventional plate making process of a lithographic printing plate precursor, a step of dissolving and removing an unnecessary image recording layer with a developer or the like is necessary after exposure. However, such additional wet processing is made unnecessary or Simplification is cited as one of the issues. In particular, in recent years, disposal of waste liquids discharged with wet processing has become a major concern for the entire industry due to consideration for the global environment, and therefore, the demand for solving the above-mentioned problems has become stronger.

On the other hand, as a simple plate making method, an image recording layer that can remove a non-image portion of a lithographic printing plate precursor in a normal printing process is used. After exposure, image recording is performed on a printing machine. A method called on-press development has been proposed in which an unnecessary portion of a layer is removed to obtain a lithographic printing plate.
As a specific method of on-press development, for example, a method of using a lithographic printing plate precursor having an image recording layer that can be dissolved or dispersed in an fountain solution, an ink solvent, or an emulsion of a fountain solution and an ink. , A method of mechanically removing the image recording layer by contact with rollers or a blanket cylinder of a printing press, cohesion force of the image recording layer by penetration of dampening water, ink solvent, etc., or between the image recording layer and the support. There is a method in which after the adhesive force is weakened, the image recording layer is mechanically removed by contact with rollers or a blanket cylinder.
In the present invention, unless otherwise specified, the “development process step” refers to using a device other than a printing press (usually an automatic developing machine) and bringing a liquid (usually an alkaline developer) into contact therewith. Refers to the process of removing the image recording layer from the infrared laser unexposed portion of the lithographic printing plate precursor to expose the hydrophilic surface, and “on-press development” refers to a liquid (usually printing ink) using a printing press. And / or a dampening solution) to remove the image recording layer of the unexposed portion of the infrared laser of the planographic printing plate precursor and to expose the hydrophilic surface.

On the other hand, in recent years, digitization technology for electronically processing, storing, and outputting image information by a computer has become widespread, and various new image output methods corresponding to such digitization technology will be put into practical use. It is becoming. Along with this, the digitized image information is carried by high-convergence radiation such as laser light, and the lithographic printing plate precursor is scanned and exposed with the light, and directly through the lithographic printing plate Computer-to-plate (CTP) technology has been attracting attention. Therefore, obtaining a lithographic printing plate precursor adapted to such a technique is one of the important technical issues.
As described above, in recent years, simplification, drying, and no processing of plate making operations have become more desirable than ever in terms of both consideration for the global environment and adaptation to digitalization. It is coming.

In general, as a pre-process for attaching a printing plate to a printing press, an operation for inspecting and identifying an image on the printing plate is performed to check whether the printing plate has been recorded as intended. Ordinary lithographic printing plate precursors with a development process generally have an image recording layer colored so that images can be checked after plate making (after development processing) and before printing (before attaching the printing plate to the printing press). It's easy to do.
However, on an on-press development type or unprocessed (no development) type lithographic printing plate precursor that does not involve development before printing, there is no image on the printing plate when the printing plate is attached to the printing press, and the plate is identified. I can't do it. In particular, whether or not it is possible to determine that a register mark (register mark) that serves as a registration mark in multi-color printing is drawn is important for the printing operation. Therefore, on-machine development type or unprocessed (no development) type lithographic printing plate precursor is required to have a means (print-out agent) for confirming an image at the stage of exposure or heating.

A printing plate using a compound that generates an acid, base, or radical by light or heat and a compound that changes color by interacting with the generated acid, base, or radical has been proposed (for example, a patent). Reference 1). It has also been proposed to use the color change of the thermally decomposable compound as a printing-out agent for a direct-drawing lithographic printing plate precursor having a heat-sensitive layer (see, for example, Patent Document 2). Furthermore, it has also been proposed to use a thermal decomposable dye having a thermal decomposition temperature of 250 ° C. or less as a print-out agent (for example, see Patent Document 3).
According to these, although color development or decoloration occurs in the exposed area and the image confirmation is improved to some extent, for example, from a practical viewpoint, the color developability is still insufficient, or the colored dye or the exposure Dyes that have not been decomposed or discolored by the dyeing of the dampening water affect the finish of the printed matter, insoluble dyes remain in the ink or dampening water, and components and dyes of the ink or dampening water And the like, and it precipitates to form residue.
JP-A-11-277927 JP 2000-335129 A JP 2003-191657 A

  An object of the present invention is to provide an on-press development type lithographic printing plate precursor capable of forming a color image with good visibility by laser exposure and having excellent printing durability, a polymerizable composition therefor, and the lithographic printing plate precursor It is to provide a lithographic printing method using

  As a result of intensive studies to achieve the above object, the present inventors have found that a printed image with good visibility can be obtained by using an azinium salt having a specific structure, and completed the present invention.

That is, the present invention is as follows.
1. (A) a compound represented by the following general formula (1), (B) an infrared absorber, and (C) a compound having at least one ethylenically unsaturated bond capable of addition polymerization. Polymerizable composition.

(In the formula, R ¹ represents a monovalent organic group, and R ² to R ⁶ each independently represents a hydrogen atom, a halogen atom, or a monovalent organic group. X ⁻ represents an arbitrary anion. At least one of A, B, and D represents a nitrogen atom, and the other represents a carbon atom, and when any of A, B, and D is a nitrogen atom, R ⁵ , R ^4, and R bonded thereto ³ represents an unshared electron pair, and R ¹ and R ² , R ² and R ³ , R ³ and R ⁴ , R ⁴ and R ⁵ , R ⁵ and R ⁶ , and R ⁶ and R in the formula ¹ may be bonded to each other to form an aromatic ring or a heterocyclic ring together with the carbon atoms to which they are bonded, and may form a condensed ring as a whole.

2. (A) In the general formula (1), one of A, B and D is a nitrogen atom, and A or D is a nitrogen atom, The polymerizable composition as described in 1 above.
3. (A) In the general formula (1), two of A, B and D are nitrogen atoms, and A and D are nitrogen atoms, The polymerizable composition as described in 1 above.
4). (A) The polymerizable composition as described in 1 above, wherein, in the general formula (1), only B of A, B and D is a nitrogen atom.
5). Said (B) infrared absorber is a cyanine pigment | dye, The polymeric composition as described in any one of said 1-4 characterized by the above-mentioned.
6). 6. The polymerizable composition as described in 5 above, wherein the (B) infrared absorber is a compound having a solvent-soluble group in the molecule.
7). The polymerization according to 6 above, wherein the solvent-soluble group of the (B) infrared absorber is at least one selected from the group consisting of an alkyloxy group, an aryloxy group, an alkyloxycarbonyl group, and an aryloxycarbonyl group. Sex composition.
8). The (B) infrared absorber has a cyanine dye structure represented by the following general formula (2), and has at least one solvent-soluble group in the molecule. Polymerizable composition.

(In the formula, Z ¹ and Z ² each independently represent an aromatic ring or a heteroaromatic ring which may have a substituent. R ³ and R ⁴ each independently represents a carbon which may have a substituent. Represents a hydrocarbon group having a number of 20 or less, and R ⁹ and R ¹⁰ each independently represents a hydrogen atom or an alkoxy group which may have a substituent, Za ⁻ is present when neutralization of charge is required. Represents a counter anion.)

9. The (B) infrared absorber has a salt structure composed of a cation and an anion, and at least one of the anion and the anion of the compound represented by (A) the general formula (1) is an inorganic anion. The polymerizable composition according to any one of 1 to 8 above.
10. 10. The polymerizable composition as described in any one of 1 to 9 above, wherein the polymerizable composition further contains (D) a binder polymer.
11. 11. The polymerizable composition as described in any one of 1 to 10 above, wherein the polymerizable composition contains (E) a microcapsule or a microgel.
12 A lithographic printing plate precursor comprising an image recording layer containing the polymerizable composition according to any one of 1 to 11 above and removed by an oily ink and / or an aqueous component on a support.
13. The above-described lithographic printing plate precursor is image-wise exposed with an infrared laser, and printing is performed by supplying an oil-based ink and an aqueous component without performing any development treatment on the exposed lithographic printing plate precursor. A planographic printing method comprising: removing an infrared laser unexposed portion of the image recording layer with an oil-based ink and / or an aqueous component in the course of the printing step.

The coloring mechanism of the present invention is not clear, but is estimated as follows.
(A) The compound represented by the general formula (1) used in the present invention has an azinium salt structure, and generates radicals by infrared laser exposure or heating. It has a function of initiating and proceeding a polymerization reaction of a compound having at least one bond, but (B) from an infrared absorber excited by infrared laser exposure, (A) an electron is converted into a compound represented by the general formula (1). It is considered that the transfer is performed and the polymerization initiating ability is expressed, and the infrared absorber (B) undergoes a structural change and a color change due to electron transfer. (A) By using the compound represented by the general formula (1), electron transfer efficiently occurs and proceeds from the excited dye, so that a large color change is obtained and excellent visibility is obtained. It is considered that a high-strength cured image is formed.
According to the planographic printing plate precursor of the invention, a color image with good visibility and high intensity can be formed by laser exposure.
In addition, the image recording layer can be applied evenly in a high density state, and the occurrence of waste during on-press development due to components in the image recording layer and the dyeing of dampening water are suppressed. It also has.

  According to the present invention, an on-press development type lithographic printing plate precursor capable of forming a color image with good visibility by laser exposure and having excellent printing durability, a polymerizable composition therefor, and the lithographic printing plate A lithographic printing method using an original plate can be provided.

Hereinafter, the present invention will be described in detail.
(Polymerizable composition)
The polymerizable composition of the present invention includes (A) a compound represented by the following general formula (1), (B) an infrared absorber, and (C) a compound having at least one ethylenically unsaturated bond capable of addition polymerization. Preferably, it further contains (D) a binder polymer. A lithographic printing plate precursor having an image recording layer containing such a polymerizable composition produces a printed image with high visibility by infrared irradiation. In addition, this lithographic printing plate precursor is subjected to a printing process without any wet development process after image recording by infrared exposure, so that oily components such as ink and fountain solution and So-called on-press development is possible in which non-image areas are removed by an aqueous component.
Hereinafter, the constituent components of the polymerizable composition will be described by taking the application of the lithographic printing plate precursor to the image recording layer as an example.

<(A) Compound Represented by General Formula (1)>
First, the compound represented by the general formula (1) will be described.

In the formula, R ¹ represents a monovalent organic group, and R ² to R ⁶ each independently represents a hydrogen atom, a halogen atom, or a monovalent organic group. X ⁻ represents an arbitrary anion. At least one of A, B, and D represents a nitrogen atom, and the other represents a carbon atom. When any of A, B, and D is a nitrogen atom, R ⁵ , R ^4, and R ³ bonded thereto each represent an unshared electron pair.
In the formula, R ¹ and R ² , R ² and R ³ , R ³ and R ⁴ , R ⁴ and R ⁵ , R ⁵ and R ⁶ , and R ⁶ and R ¹ are bonded to each other. An aromatic ring or a hetero ring may be formed together with the carbon atom, and a condensed ring may be formed as a whole.
From the viewpoint of improving the plate inspection property, it is particularly preferable that one or two of A, B and D are nitrogen atoms.
From the viewpoint of availability of raw materials, (1) when either A or D is a nitrogen atom,
(2) It is preferable when both A and D are nitrogen atoms, and (3) when only B is a nitrogen atom.

The monovalent organic group represented by R ^{1 to} R ⁶ will be described.
When R ^{1 to} R ⁶ represent a monovalent organic group, examples of the monovalent organic group include an amino group, a substituted amino group, a substituted carbonyl tomb, a hydroxyl group, a substituted oxy group, a thiol group, a thioether group, Silyl group, nitro group, cyano group, alkyl group, alkenyl group, aryl group, heterocyclic group, sulfo group, substituted sulfonyl group, sulfonate group, substituted sulfinyl group, phosphono group, substituted phosphono group, phosphonate group, substituted phosphonate group, In the case where introduction is possible, it may further have a substituent.

Examples of the alkyl group represented by R ^{1 to} R ⁶ include linear, branched or cyclic alkyl groups having 1 to 20 carbon atoms. Among these, a linear alkyl group having 1 to 12 carbon atoms, a branched alkyl group having 3 to 12 carbon atoms, and a cyclic alkyl group having 5 to 10 carbon atoms are more preferable. Specific examples thereof include methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, hexadecyl group, octadecyl group. , Eicosyl group, isopropyl group, isobutyl group, s-butyl group, t-butyl group, isopentyl group, neopentyl group, 1-methylbutyl group, isohexyl group, 2-ethylhexyl group, 2-methylhexyl group, cyclohexyl group, cyclopentyl group And 2-norbornyl group.

When the alkyl group represented by R ^{1 to} R ⁶ has a substituent (that is, when it is a substituted alkyl group), the alkyl part of the substituted alkyl group includes the above-described alkyl group having 1 to 20 carbon atoms. A divalent organic residue obtained by removing any one of the hydrogen atoms can be exemplified, and the preferable range of the number of carbon atoms is the same as that of the alkyl group.

Preferable specific examples of the substituted alkyl group represented by R ^{1 to} R ⁶ include a chloromethyl group, a bromomethyl group, a 2-chloroethyl group, a trifluoromethyl group, a methoxymethyl group, a methoxycarbonylmethyl group, an isopropoxymethyl group, Butoxymethyl, s-butoxybutyl, methoxyethoxyethyl, allyloxymethyl, phenoxymethyl, acetyloxymethyl, methylthiomethyl, tolylthiomethyl, pyridylmethyl, tetramethylpiperidinylmethyl, N-acetyltetramethylpiperidinylmethyl group, trimethylsilylmethyl group, methoxyethyl group, ethylaminoethyl group, diethylaminopropyl group, morpholinopropyl group, acetyloxymethyl group, benzoyloxymethyl group, N-cyclohexylcarbamo Ruoxyethyl group, N-phenylcarbamoyloxyethyl group, acetylaminoethyl group, N-methylbenzoylaminopropyl group, 2-oxoethyl group, 2-oxopropyl group, carboxypropyl group, methoxycarbonylethyl group, allyloxycarbonylbutyl group, Chlorophenoxycarbonylmethyl group,

Carbamoylmethyl group, N-methylcarbamoylethyl group, N, N-dipropylcarbamoylmethyl group, N- (methoxyphenyl) carbamoylethyl group, N-methyl-N- (sulfophenyl) carbamoylmethyl group, sulfobutyl group, sulfonatobutyl group Sulfamoylbutyl group, N-ethylsulfamoylmethyl group, N, N-dipropylsulfamoylpropyl group, N-tolylsulfamoylpropyl group, N-methyl-N- (phosphonophenyl) sulfamoyl Octyl group, phosphonobutyl group, phosphonatohexyl group, diethylphosphonobutyl group, diphenylphosphonopropyl group, methylphosphonobutyl group, methylphosphonatobutyl group, tolylphosphonohexyl group, tolylphosphonatohexyl group, phosphonooxy Propyl group, phosphona Oxybutyl group, benzyl group, phenethyl group, α-methylbenzyl group, 1-methyl-1-phenylethyl group, p-methylbenzyl group, cinnamyl group, allyl group, 1-propenylmethyl group, 2-butenyl group, 2- Examples thereof include a methylallyl group, a 2-methylpropenylmethyl group, a 2-propynyl group, a 2-butynyl group, and a 3-butynyl group.

Examples of the substituent that can be introduced into the alkyl group represented by R ^{1 to} R ⁶ include a monovalent atom composed of a nonmetallic atom exemplified below in addition to the substituents described in the description of the substituted alkyl group. Substituents are also included. Preferred examples including the above-described substituent include a halogen atom (—F, —Br, —Cl, —I), hydroxyl group, alkoxy group, aryloxy group, mercapto group, alkylthio group, arylthio group, alkyldithio group, aryl. Dithio group, amino group, N-alkylamino group, N, N-dialkylamino group, N-arylamino group, N, N-diarylamino group, N-alkyl-N-arylamino group, acyloxy group, carbamoyloxy group N-alkylcarbamoyloxy group, N-arylcarbamoyloxy group, N, N-dialkylcarbamoyloxy group, N, N-diarylcarbamoyloxy group, N-alkyl-N-arylcarbamoyloxy group, alkylsulfoxy group, aryl A sulfoxy group, an acylthio group, an acylamino group, -Alkylacylamino group, N-arylacylamino group, ureido group, N'-alkylureido group, N ', N'-dialkylureido group, N'-arylureido group, N', N'-diarylureido group, N′-alkyl-N′-arylureido group, N-alkylureido group, N-arylureido group, N′-alkyl-N-alkylureido group, N′-alkyl-N-arylureido group, N ′, N '-Dialkyl-N-alkylureido group, N', N'-dialkyl-N-arylureido group, N'-aryl-N-alkylureido group, N'-aryl-N-arylureido group, N ', N '-Diaryl-N-alkylureido group, N', N'-diaryl-N-arylureido group, N'-alkyl-N'-aryl-N-alkylureido group, N'-alkyl A ru-N′-aryl-N-arylureido group,

Alkoxycarbonylamino group, aryloxycarbonylamino group, N-alkyl-N-alkoxycarbonylamino group, N-alkyl-N-aryloxycarbonylamino group, N-aryl-N-alkoxycarbonylamino group, N-aryl-N -Aryloxycarbonylamino group, formyl group, acyl group, carboxyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, N-alkylcarbamoyl group, N, N-dialkylcarbamoyl group, N-arylcarbamoyl group, N, N- di arylcarbamoyl group, N- alkyl -N- arylcarbamoyl group, an alkylsulfinyl group, an arylsulfinyl group, an alkylsulfonyl group, an arylsulfonyl group, a sulfo group (-SO 3 _H) and its conjugated base group (scan Phonato group), alkoxysulfonyl group, aryloxysulfonyl group, sulfinamoyl group, N-alkylsulfinamoyl group, N, N-dialkylsulfinaimoyl group, N-arylsulfinamoyl group, N, N-diaryl Sulfinamoyl group, N-alkyl-N-arylsulfinamoyl group, sulfamoyl group, N-alkylsulfamoyl group, N, N-dialkylsulfamoyl group, N-arylsulfamoyl group, N, N- Diarylsulfamoyl group, N-alkyl-N-arylsulfamoyl group,

A phosphono group (—PO ₃ H ₂ ) and its conjugate base group (referred to as phosphonato group), a dialkylphosphono group (—PO ₃ (alkyl) ₂ ) “alkyl = alkyl group, the same shall apply hereinafter”, a diarylphosphono group ( -PO _{3 (aryl) 2)} "aryl = aryl group, hereinafter the" alkylaryl phosphono group _{(-PO 3 (alkyl) (aryl} )), monoalkyl phosphono group _(-PO 3 _(alkyl)) and its Conjugated base group (referred to as alkylphosphonate group), monoarylphosphono group (—PO ₃ H (aryl)) and its conjugate base group (referred to as arylphosphonate group), phosphonooxy group (—OPO ₃ H ₂₎ ) and its conjugated base group (referred to as phosphonatooxy group), dialkylphosphono group _(-OPO 3 H _(alkyl) 2), Aryl phosphono group _{(-OPO 3 (aryl) 2)} , alkylaryl phosphono group _{(-OPO 3 (alkyl) (aryl} )), monoalkyl phosphono group _(-OPO 3 H _(alkyl)) and its Conjugated base group (referred to as alkylphosphonatoxy group), monoarylphosphonooxy group (—OPO ₃ H (aryl)) and its conjugate base group (referred to as arylphosphonatoxy group), cyano group, nitro group Aryl group, alkenyl group, alkynyl group, heterocyclic group, silyl group, and the like.

Specific examples of the alkyl moiety in the substituent that may be introduced into the alkyl group represented by R ¹ to R ⁶ are the same as in the case R ¹ to R ⁶ described above is a substituted alkyl group, the preferred range is also the same is there.
Specific examples of the aryl moiety in the substituent that can be introduced into the alkyl group represented by R ^{1 to} R ⁶ include phenyl group, biphenyl group, naphthyl group, tolyl group, xylyl group, mesityl group, cumenyl group, chlorophenyl. Group, bromophenyl group, chloromethylphenyl group, hydroxyphenyl group, methoxyphenyl group, ethoxyphenyl group, phenoxyphenyl group, acetoxyphenyl group, benzoyloxyphenyl group, methylthiophenyl group, phenylthiophenyl group, methylaminophenyl group Dimethylaminophenyl group, acetylaminophenyl group, carboxyphenyl group, methoxycarbonylphenyl group, ethoxyphenylcarbonyl group, phenoxycarbonylphenyl group, N-phenylcarbamoylphenyl group, cyanophenyl group, sulfo Eniru group, a sulfophenyl group, phosphono phenyl group, phosphonium Hona preparative phenyl group, and the like.

Examples of the alkenyl group represented by R ^{1 to} R ⁶ include alkenyl groups having 2 to 20 carbon atoms. Among these, an alkenyl group having 2 to 10 carbon atoms is preferable, and an alkenyl group having 2 to 8 carbon atoms is more preferable. The alkenyl group may further have a substituent. Examples of the substituent that can be introduced include a halogen atom, an alkyl group, a substituted alkyl group, an aryl group, and a substituted aryl group. The halogen atom is a linear or branched chain having 1 to 10 carbon atoms. A cyclic alkyl group is preferred. Specific examples of the alkenyl group include, for example, vinyl group, 1-propenyl group, 1-butenyl group, cinnamyl group, 1-pentenyl group, 1-hexenyl group, 1-octenyl group, 1-methyl-1-propenyl group, A 2-methyl-1-propenyl group, a 2-methyl-1-butenyl group, a 2-phenyl-1-ethenyl group, a 2-chloro-1-ethenyl group, and the like can be given.

Examples of the alkynyl group represented by R ^{1 to} R ⁶ include alkynyl groups having 2 to 20 carbon atoms. Among these, an alkynyl group having 2 to 10 carbon atoms is preferable, and an alkynyl group having 2 to 8 carbon atoms is more preferable. Specific examples thereof include ethynyl group, 1-propynyl group, 1-butynyl group, phenylethynyl group, trimethylsilylethynyl group and the like.

Examples of the aryl group represented by R ^{1 to} R ⁶ include a benzene ring, a group in which 2 to 3 benzene rings form a condensed ring, and a group in which a benzene ring and a 5-membered unsaturated ring form a condensed ring. Can be mentioned. Specific examples include a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group, an indenyl group, an acenaphthenyl group, and a fluorenyl group. Among these, a phenyl group and a naphthyl group are more preferable.

In addition, the aryl group represented by R ^{1 to} R ⁶ may have a substituent on the carbon atom forming the ring, and as such a substituent, a monovalent group composed of a nonmetallic atom. The substituent of this is mentioned. Preferable examples of the substituent to be introduced include those described above in the description of the alkyl group, the substituted alkyl group, and the substituent in the substituted alkyl group.

The heterocyclic group represented by R ^{1 to} R ⁶ is preferably a 3- to 8-membered heterocyclic group, more preferably a 3- to 6-membered heterocyclic group containing a nitrogen atom, an oxygen atom, or a sulfur atom. A 5- to 6-membered heterocyclic group containing a nitrogen atom, oxygen atom or sulfur atom is more preferred. Specifically, pyrrole ring group, furan ring group, thiophene ring group, benzopyrrole ring group, benzofuran ring group, benzothiophene ring group, pyrazole ring group, isoxazole ring group, isothiazole ring group, indazole ring group, benzoiso Xazole ring group, benzoisothiazole ring group, imidazole ring group, oxazole ring group, thiazole ring group, benzimidazole ring group, benzoxazole ring group, benzothiazole ring group, pyridine ring group, quinoline ring group, isoquinoline ring group, Pyridazine ring group, pyrimidine ring group, pyrazine ring group, phthalazine ring group, quinazoline ring group, quinoxaline ring group, acylidin ring group, phenanthridine ring group, carbazole ring group, purine ring group, pyran ring group, piperidine ring group, Piperazine ring group, morpholine ring group, indole ring group, indolizine ring group, Road ring group, a cinnoline ring group, an acridine ring group, a phenothiazine ring group, a tetrazole ring group, a triazine ring group, and the like.

In addition, the heterocyclic group represented by R ^{1 to} R ⁶ may have a substituent on the carbon atom forming the ring, and such a substituent is composed of a nonmetallic atom. Valent substituents. Preferable examples of the substituent to be introduced include those described above in the description of the alkyl group, the substituted alkyl group, and the substituent in the substituted alkyl group.

The silyl group represented by R ^{1 to} R ⁶ may have a substituent, is preferably a silyl group having 0 to 30 carbon atoms, more preferably a silyl group having 3 to 20 carbon atoms, and 3 carbon atoms. To 10 silyl groups are more preferred. Specific examples thereof include a trimethylsilyl group, a triethylsilylyl group, a tripropylsilyl group, a triisopropylsilyl group, a cyclohexyldimethylsilyl group, and a dimethylvinylsilyl group.

The thiol group represented by R ^{1 to} R ⁶ may have a substituent, preferably a thiol group having 0 to 30 carbon atoms, more preferably a thiol group having 3 to 20 carbon atoms, A thiol group of formula 1 to 10 is more preferred. Specific examples thereof include a mercaptomethyl group, a mercaptoethyl group, a 4-mercaptocyclohexyl group, and a 4-mercaptophenyl group.

The thioether group represented by R ^{1 to} R ⁶ may have a substituent, preferably a thioether group having 0 to 30 carbon atoms, more preferably a thioether group having 3 to 20 carbon atoms, A thioether group having a number of 1 to 10 is more preferable.
Specific examples thereof include alkylthio groups such as methylthio group, ethylthio group and cyclohexylthio group, arylthio groups such as phenylthio group, and the like.
Examples of the halogen atom represented by R ^{2 to} R ⁶ include a fluorine atom, a bromine atom, a chlorine atom, and an iodine atom. Among these, a chlorine atom and a bromine atom are preferable.

The substituted oxy group (R ^{06 O-),} can be used a group R ⁰⁶ is a monovalent nonmetallic atom group exclusive of a hydrogen atom. Preferred substituted oxy groups include alkoxy, aryloxy, acyloxy, carbamoyloxy, N-alkylcarbamoyloxy, N-arylcarbamoyloxy, N, N-dialkylcarbamoyloxy, N, N-diarylcarbamoyloxy. Groups, N-alkyl-N-arylcarbamoyloxy groups, alkylsulfoxy groups, arylsulfoxy groups, phosphonooxy groups, and phosphonatoxy groups. Examples of the alkyl group and aryl group in these include the alkyl groups, substituted alkyl groups, aryl groups, and substituted aryl groups described above. Examples of the acyl group (R ⁰⁷ CO—) in the acyloxy group include those in which R ⁰⁷ is an alkyl group, a substituted alkyl group, an aryl group, or a substituted aryl group mentioned above. Among these substituents, an alkoxy group, an aryloxy group, an acyloxy group, and an arylsulfoxy group are more preferable. Specific examples of preferred substituted oxy groups include methoxy, ethoxy, propyloxy, isopropyloxy, butyloxy, pentyloxy, hexyloxy, dodecyloxy, benzyloxy, allyloxy, phenethyloxy, Carboxyethyloxy group, methoxycarbonylethyloxy group, ethoxycarbonylethyloxy group, methoxyethoxy group, phenoxyethoxy group, methoxyethoxyethoxy group, ethoxyethoxyethoxy group, morpholinoethoxy group, morpholinopropyloxy group, allyloxyethoxyethoxy group, Phenoxy group, tolyloxy group, xylyloxy group, mesityloxy group, mesityloxy group, cumenyloxy group, methoxyphenyloxy group, ethoxyphenyloxy group, chlorophenyl Alkoxy group, bromophenyl group, acetyloxy group, benzoyloxy group, naphthyloxy, phenylsulfonyloxy group, a phosphonooxy groups, phosphonatooxy group, and the like.

The amino group may be a substituted amino group including an amide group. As the substituted amino group (R ⁰⁸ NH—, (R ⁰⁹ ) (R ⁰¹⁰ ) N—) including an amide group, R ⁰⁸ , R ⁰⁹ , and R ⁰¹⁰ are a group composed of a monovalent nonmetallic atomic group excluding a hydrogen atom. Can be used. R ⁰⁹ and R ⁰¹⁰ may combine to form a ring. Preferred examples of the substituted amino group include an N-alkylamino group, an N, N-dialkylamino group, an N-arylamino group, an N, N-diarylamino group, an N-alkyl-N-arylamino group, an acylamino group, N-alkylacylamino group, N-arylacylamino group, ureido group, N′-alkylureido group, N ′, N′-dialkylureido group, N′-arylureido group, N ′, N′-diarylureido group N′-alkyl-N′-arylureido group, N-alkylureido group, N-arylureido group, N′-alkyl-N-alkylureido group, N′-alkyl-N-arylureido group, N ′, N′-dialkyl-N-alkylureido group, N′-alkyl-N′-arylureido group, N ′, N′-dialkyl-N-alkylureido group, N ′, '-Dialkyl-N'-aryl, ureido group, N'-aryl-N-alkylureido group, N'-aryl-N-arylureido group, N', N'-diaryl-N-alkylureido group, N ' , N′-diaryl-N-arylureido group, N′-alkyl-N′-aryl-N-alkylureido group, N′-alkyl-N′-aryl-N-arylureido group, alkoxycarbonylamino group, aryl Roxycarbonylamino group, N-alkyl-N-alkoxycarbonylamino group, N-alkyl-N-aryloxycarbonylamino group, N-aryl-N-alkoxycarbonylamino group, N-aryl-N-aryloxycarbonylamino group Is mentioned. Examples of the alkyl group and aryl group include those described above as the alkyl group, substituted alkyl group, aryl group, and substituted aryl group, such as acylamino group, N-alkylacylamino group, and N-arylacylamino. ^{R 07} groups definitive acyl group ^(R 07 CO-) are as described above. Of these, more preferred are an N-alkylamino group, an N, N-dialkylamino group, an N-arylamino group, and an acylamino group. Specific examples of preferred substituted amino groups include methylamino group, ethylamino group, diethylamino group, morpholino group, piperidino group, pyrrolidino group, phenylamino group, benzoylamino group, acetylamino group and the like.

As the substituted sulfonyl group (R ⁰¹¹ —SO ₂ —), those in which R ⁰¹¹ is a group composed of a monovalent nonmetallic atomic group can be used. More preferable examples include an alkylsulfonyl group, an arylsulfonyl group, and a substituted or unsubstituted sulfamoyl group. Examples of the alkyl group and aryl group in these include those described above as the alkyl group, substituted alkyl group, aryl group, and substituted aryl group. Specific examples of such a substituted sulfonyl group include butylsulfonyl group, phenylsulfonyl group, chlorophenylsulfonyl group, sulfamoyl group, N-alkylsulfamoyl group, N, N-dialkylsulfamoyl group, N-arylsulfuryl group. A famoyl group, an N-alkyl-N-arylsulfamoyl group, and the like.

As described above, the sulfonate group (—SO ₃ —) means a conjugated base anion group of the sulfo group (—SO ₃ H), and is usually preferably used together with a counter cation. Examples of such counter cations include those generally known, that is, various oniums (ammoniums, sulfoniums, phosphoniums, iodoniums, aziniums, etc.), and metal ions (Na ⁺ , K +, Ca ^2+). , Zn ^2+, etc.).

As the substituted carbonyl group (R ⁰¹³ —CO—), a group in which R ⁰¹³ is a monovalent nonmetallic atomic group can be used. Preferred examples of the substituted carbonyl group include formyl group, acyl group, carboxyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, N-alkylcarbamoyl group, N, N-dialkylcarbamoyl group, N-arylcarbamoyl group, N, N-diarylcarbamoyl group, N-alkyl-N′-arylcarbamoyl group may be mentioned. Examples of the alkyl group and aryl group in these include those described above as the alkyl group, substituted alkyl group, aryl group, and substituted aryl group. Among these, more preferred substituted carbonyl groups include formyl group, acyl group, carboxyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, N-alkylcarbamoyl group, N, N-dialkylcarbamoyl group, N-ary. A rucarbamoyl group can be mentioned, and even more preferred are a formyl group, an acyl group, an alkoxycarbonyl group and an aryloxycarbonyl group. Specific examples of preferred substituted carbonyl groups include formyl group, acetyl group, benzoyl group, carboxyl group, methoxycarbonyl group, ethoxycarbonyl group, allyloxycarbonyl group, dimethylaminophenylethenylcarbonyl group, methoxycarbonylmethoxycarbonyl group, N -Methylcarbamoyl group, N-phenylcarbamoyl group, N, N-diethylcarbamoyl group, morpholinocarbonyl group and the like.

As the substituted sulfinyl group (R ⁰¹⁴ —SO—), a group in which R ⁰¹⁴ is a monovalent nonmetallic atomic group can be used. Preferred examples include alkylsulfinyl group, arylsulfinyl group, sulfinamoyl group, N-alkylsulfinamoyl group, N, N-dialkylsulfinamoyl group, N-arylsulfinamoyl group, N, N-diarylsulfinamoyl. Group, N-alkyl-N-arylsulfinamoyl group. Examples of the alkyl group and aryl group in these include those described above as the alkyl group, substituted alkyl group, aryl group, and substituted aryl group. Of these, more preferred examples include an alkylsulfinyl group and an arylsulfinyl group. Specific examples of such a substituted sulfinyl group include a hexylsulfinyl group, a benzylsulfinyl group, and a tolylsulfinyl group.

  The substituted phosphono group means a group in which one or two hydroxyl groups on the phosphono group are substituted with other organic oxo groups. Preferred examples include the above-mentioned dialkylphosphono group, diarylphosphono group, alkylaryl. Examples thereof include a phosphono group, a monoalkylphosphono group, and a monoarylphosphono group. Of these, dialkylphosphono groups and diarylphosphono groups are more preferred. Specific examples thereof include a diethyl phosphono group, a dibutyl phosphono group, a diphenyl phosphono group, and the like.

Phosphonato group _{(-PO 3 H 2 -, -} PO 3 H-) and the meaning of a phosphono group _(-PO 3 _{H 2),} first dissociation or acid, a conjugated base anion group derived from the second dissociation acid To do. Usually, it is preferable to use it with a counter cation. Examples of such counter cations include those generally known, that is, various oniums (ammonium compounds, sulfonium compounds, phosphonium compounds, iodonium compounds, azinium compounds, etc.), and metal ions (Na ⁺ , K ⁺ , Ca ²⁺ , Zn ^2+, etc.).

The substituted phosphonato group is a conjugated base anion group obtained by substituting one hydroxyl group with an organic oxo group among the above-mentioned substituted phosphono groups. Specific examples thereof include the above-described monoalkylphosphono groups (—PO ₃ H (Alkyl)), and a conjugate base of a monoarylphosphono group (—PO ₃ H (aryl)).

In addition, R ¹ and R ² , R ² and R ³ , R ³ and R ⁴ , R ⁴ and R ⁵ , and R ⁵ and R ¹ in the general formula (1) are bonded to each other, You may form the condensed ring of a benzene ring and a heterocyclic ring with the carbon atom which exists.

Preferred embodiments of R ^{1 to} R ⁶ are listed below.
R ¹ is preferably an alkyl group which may have a substituent having 1 to 20 carbon atoms, more preferably an alkyl group which may have a substituent having 3 to 20 carbon atoms, and a substituent having 6 to 20 carbon atoms. An alkyl group which may have a more preferable is more preferable.
R ^{2 to} R ⁶ are preferably a hydrogen atom, an alkyl group which may have a substituent having 3 to 20 carbon atoms, an aromatic group or a heterocyclic group, and may have a substituent having 6 to 20 carbon atoms. A good alkyl group, aromatic group or heterocyclic group is more preferred.
Further, from the viewpoint of improving the plate inspection property, R ¹ and R ² , R ² and R ³ , R ³ and R ⁴ , R ⁴ and R ⁵ , R ⁵ and R ⁶ , and R ⁶ and R ¹ in the formula are It is preferable that they are bonded to each other to form an aromatic ring or a heterocyclic ring together with the carbon atoms to which they are bonded to form a condensed ring as a whole. In particular, the total number of condensed rings is two or three from the viewpoint of improving the plate inspection property.

  From the viewpoint of visibility, the log P value of the skeleton (cation part) having a specific structure in the compound represented by the general formula (1) is preferably 2.00 or more, more preferably 3.00 or more, and still more preferably. It is desirable to have 4.00 or more. Here, the log P value means a common logarithm of a partition coefficient P (Partition Coefficient), and how an organic compound is distributed in an equilibrium of a two-phase system of oil (generally 1-octanol) and water. It is a physical property value that expresses as a quantitative numerical value.

logP = log (Coil / Cwater)
Coil = Molar concentration in oil phase Cwater = Molar concentration in water phase

The “logP” value here refers to a skeleton (cation part) having a specific structure, a logP value estimation program developed by C. Hansch, A. Leo et al., Medchem project of Biomon University and Biobyte, Inc .: CLOGP (Daylight This is a value calculated using the CLOGP program (algorithm = 4.01 fragment database = 17) incorporated in the Chemical Information System system: PCModels (ver 1.02). This program is based on the “Hansch-Leo fragment method”, which divides the chemical structure into substructures (fragments) and estimates the logP value by summing the logP contributions assigned to the fragment. Yes. This method is described in detail in the following documents, and this description can be referred to.
C. Hansch & A. Leo. Substituent Constants For Correlation Analysis in Chemistry and Biology John Wiley & Sons .; AJ Leo. "Calculating log Poct from structure."

X < ^- > is an arbitrary anion and is preferably an acid anion. Specific examples include a halogen atom anion, BF ₄ ⁻ , BCl ₄ ⁻ , ZnCl ₄ ⁻ , SbCl ₆ ⁻ , FeCl ₄ ⁻ , GaCl ₄ ⁻ , GaBr ₄ ⁻ , AlI ₄ ⁻ , AlCl ₄ ⁻ , SbF ₆ ⁻ , CF ₃ SO ₃ ⁻ , PF ₆ ⁻ , BPh ₄ ⁻ , condensed polynuclear sulfonate anions such as naphthalene-1-sulfonic acid, anthracene-1-sulfonic acid, anthraquinone sulfonate anion, anthracene sulfonate anion, sulfonate group-containing dyes ( An anion having a sulfo group and a chromophoric group), but is not limited thereto.
From the viewpoint of improving visibility, X ⁻ is preferably an inorganic anion or an anion of a strong acid. From such a viewpoint, PF ₆ ⁻ , BF ₄ ⁻ , CF ₃ SO ₃ ⁻ , C ₄ F ₉ SO _{3 are used.} ^- , Among which PF ₆ ^- is most preferable.

Further, the compound represented by the general formula (1), through any one of R ¹ to R ^6, may be introduced into the polymer side chain, and a preferred embodiment.
As an aspect in which the compound represented by the general formula (1) is introduced into the polymer side chain, a compound represented by the following general formula (3) is particularly preferable.
In this embodiment, it is considered that (C) a compound having at least one addition-polymerizable ethylenically unsaturated bond can form a three-dimensional crosslink. Furthermore, since the three-dimensional crosslinked structure can be formed at a higher density by using a polymer in which two or more such structures are introduced into the side chain, it is preferable from the viewpoint of improving sensitivity and printing durability. It is done.

In General Formula (3), R ^{2 to} R ⁶ represent a hydrogen atom, a halogen atom, or a monovalent organic group. P represents a polymer main chain. L represents a single bond or a divalent organic linking group. m represents an integer of 1 or more, and X ⁻ represents an anion. A, B, and D are synonymous with those in the general formula (1).

The monovalent organic group represented by R ^{2 to} R ⁶ in the general formula (3) is synonymous with the monovalent organic group represented by R ^{2 to} R ⁶ in the general formula (1), and is in a preferred range. Is the same.

  Although there is no restriction | limiting in particular in the polymer principal chain represented by P, Preferably, a polyvinyl chain, a polyurethane chain, a polyacetal chain etc. are mentioned. Among these, from the viewpoint of printing durability when applied to the recording layer of a lithographic printing plate precursor, a poly (meth) acrylate chain, a polystyrene chain, and the like are particularly preferable.

  The divalent organic linking group represented by L is a divalent organic group composed of nonmetallic atoms, including 1 to 60 carbon atoms, 0 to 10 nitrogen atoms, 0 To 50 oxygen atoms, 1 to 100 hydrogen atoms, and 0 to 20 sulfur atoms are preferred. More specific examples include organic linking groups constituted by the following structures alone or in combination.

  The organic linking group represented by L may further have a substituent. Examples of the substituent that can be introduced include a halogen atom, a hydroxyl group, a carboxyl group, a sulfonate group, a nitro group, a cyano group, and an amide group. Amino group, alkyl group, alkenyl group, alkynyl group, aryl group, substituted oxy group, substituted sulfonyl group, substituted carbonyl group, substituted sulfinyl group, sulfo group, phosphono group, phosphonato group, silyl group, heterocyclic group, etc. Can be mentioned.

m is an integer greater than or equal to 1, 2-6 are preferable and 2-3 are more preferable.
X ⁻ in the general formula (3) has the same meaning as X ⁻ in the general formula (1), and the preferred range is also the same.

  Specific examples of the compounds represented by the general formula (1) and the general formula (3) [Exemplary compounds (A-1) to (A-24)] are listed below, but the scope of the present invention is limited to these. Is not to be done.

  (A) Only 1 type may be used for the compound represented by General formula (1), and 2 or more types may be used together. In that case, a monomer, a dimer, and a polymer can be used in combination with different types of compounds.

As content of the compound represented by (A) general formula (1) in this invention, 0.1-50 mass% is preferable in an image recording layer total solid, More preferably, it is 0.5-30 mass. %, And more preferably 1 to 20% by mass.
When the content is within this range, good sensitivity and good stain resistance of the non-image area during printing can be obtained. In addition to the image recording layer, the compound (A) represented by the general formula (1) can be added to another layer.

<Other polymerization initiators>
In the present invention, since the compound represented by (A) the general formula (1) has a polymerization initiating ability, other polymerization initiators are not essential, but as long as the effects of the present invention are not impaired, (A) Other polymerization initiators other than the compound represented by the general formula (1) can be used in combination. The polymerization initiator that can be used in combination with the present invention is a compound that generates radicals by energy of light, heat, or both, and initiates and accelerates polymerization of a compound having a polymerizable unsaturated group, and is known in the art. A thermal polymerization initiator, a compound having a bond with a small bond dissociation energy, a photopolymerization initiator, and the like. The compound that generates radicals preferably used in the present invention refers to a compound that generates radicals by thermal energy and initiates and accelerates polymerization of a compound having a polymerizable unsaturated group. As the thermal radical generator according to the present invention, a known polymerization initiator, a compound having a bond with small bond dissociation energy, or the like can be appropriately selected and used. Moreover, the compound which generate | occur | produces a radical can be used individually or in combination of 2 or more types.

Examples of the compound that generates radicals include (a) an organic halide, (b) a carbonyl compound, (c) an organic peroxide, (d) an azo polymerization initiator, (e) an azide compound, and (f) a metallocene. Compounds, (g) hexaarylbiimidazole compounds, (h) organic boric acid compounds, (i) disulfone compounds, (j) oxime ester compounds, (k) onium salt compounds, and the like.
Hereinafter, each compound will be described.

  (A) Specific examples of organic halides include Wakabayashi et al., “Bull Chem. Soc Japan” 42, 2924 (1969), US Pat. No. 3,905,815, Japanese Patent Publication No. 46-4605, JP-A 48-36281, JP-A 55-32070, JP-A 60-239736, JP-A 61-169835, JP-A 61-169837, JP-A 62-58241, JP Sho 62-212401, JP-A 63-70243, JP-A 63-298339, M.S. P. The compound described in Hutt “Journal of Heterocyclic Chemistry” 1 (No 3), (1970) ”is exemplified, and in particular, an oxazole compound substituted with a trihalomethyl group: S-triazine compound.

  More preferably, an s-triazine derivative having at least one mono, di, or trihalogen-substituted methyl group bonded to the s-triazine ring, specifically, for example, 2,4,6-tris (monochloromethyl)- s-triazine, 2,4,6-tris (dichloromethyl) -s-triazine, 2,4,6-tris (trichloromethyl) -s-triazine, 2-methyl-4,6-bis (trichloromethyl)- s-triazine, 2-n-propyl-4,6-bis (trichloromethyl) -s-triazine, 2- (α, α, β-trichloroethyl) -4,6-bis (trichloromethyl) -s-triazine 2-phenyl-4,6-bis (trichloromethyl) -s-triazine, 2- (p-methoxyphenyl) -4,6-bis (trichloromethyl) -s-triazine, -(3,4-epoxyphenyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (p-chlorophenyl) -4,6-bis (trichloromethyl) -s-triazine, 2- [1 -(P-methoxyphenyl) -2,4-butadienyl] -4,6-bis (trichloromethyl) -s-triazine, 2-styryl-4,6-bis (trichloromethyl) -s-triazine, 2- ( p-methoxystyryl) -4,6-bis (trichloromethyl) -s-triazine, 2- (pi-propyloxystyryl) -4,6-bis (trichloromethyl) -s-triazine, 2- (p -Tolyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (4-natoxynaphthyl) -4,6-bis (trichloromethyl) -s-triazine, 2-pheni Thio-4,6-bis (trichloromethyl) -s-triazine, 2-benzylthio-4,6-bis (trichloromethyl) -s-triazine, 2,4,6-tris (dibromomethyl) -s-triazine, 2,4,6-tris (tribromomethyl) -s-triazine, 2-methyl-4,6-bis (tribromomethyl) -s-triazine, 2-methoxy-4,6-bis (tribromomethyl) -S-triazine and the like.

  (B) Examples of carbonyl compounds include benzophenone, Michler's ketone, 2-methylbenzophenone, 3-methylbenzophenone, 4-methylbenzophenone, 2-chlorobenzophenone, 4-bromobenzophenone, 2-carboxybenzophenone and other benzophenone derivatives, 2,2- Dimethoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, 1-hydroxycyclohexyl phenylketone, α-hydroxy-2-methylphenylpropanone, 1-hydroxy-1-methylethyl- (p-isopropylphenyl) ketone, 1-hydroxy-1- (p-dodecylphenyl) ketone, 2-methyl- (4 ′-(methylthio) phenyl) -2-morpholino-1-propanone, 1,1,1-trichloromethyl- (p-butylphenol) E) acetophenone derivatives such as ketones, thioxanthone derivatives such as thioxanthone, 2-ethylthioxanthone, 2-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, Examples thereof include benzoic acid ester derivatives such as ethyl p-dimethylaminobenzoate and ethyl p-diethylaminobenzoate.

  (C) Examples of the organic peroxide include trimethylcyclohexanone peroxide, acetylacetone peroxide, 1,1-bis (tert-butylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (tert -Butylperoxy) cyclohexane, 2,2-bis (tert-butylperoxy) butane, tert-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, 2,5-dimethylhexane-2,5- Dihydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, tert-butylcumyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di (tert-butylperoxy) Hexane, 2 5-Oxanoyl peroxide, succinic peroxide, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, di-2-ethoxyethyl peroxide Carbonate, dimethoxyisopropylperoxycarbonate, di (3-methyl-3-methoxybutyl) peroxydicarbonate, tert-butylperoxyacetate, tert-butylperoxypivalate, tert-butylperoxyneodecanoate, tert -Butyl peroxyoctanoate, tert-butyl peroxylaurate, tersyl carbonate, 3,3 ', 4,4'-tetra- (t-butylperoxycarbonyl) benzophenone, 3,3', 4 4′-tetra- (t-hexylperoxycarbonyl) benzophenone, 3,3 ′, 4,4′-tetra- (p-isopropylcumylperoxycarbonyl) benzophenone, carbonyldi (t-butylperoxydihydrogen diphthalate ), Carbonyldi (t-hexylperoxydihydrogen diphthalate), and the like.

(D) As the azo compound, for example, an azo compound described in JP-A-8-108621 can be used.
(E) Examples of the azide compound include an azide polymer described in Japanese Society of Photography Society 1968 Spring Research Presentation Abstract, page 55, 2-azidobenzoxazole, benzoylazide described in US Pat. No. 3,282,693, A compound such as azidobenzimidazole may be mentioned.
(F) As the metallocene compound, JP-A-59-152396, JP-A-61-151197, JP-A-63-41484, JP-A-2-249, JP-A-2-4705 Various titanocene compounds described in JP-A-5-83588, such as di-cyclopentadienyl-Ti-bis-phenyl, di-cyclopentadienyl-Ti-bis-2,6-difluorophen-1- , Di-cyclopentadienyl-Ti-bis-2,4-di-fluorophen-1-yl, di-cyclopentadienyl-Ti-bis-2,4,6-trifluorophen-1-yl Di-cyclopentadienyl-Ti-bis-2,3,5,6-tetrafluorophen-1-yl, di-cyclopentadienyl-Ti-bis-2,3,4,5,6-pen Fluorophen-1-yl, di-methylcyclopentadienyl-Ti-bis-2,6-difluorophen-1-yl, di-methylcyclopentadienyl-Ti-bis-2,4,6-trifluoro Phen-1-yl, di-methylcyclopentadienyl-Ti-bis-2,3,5,6-tetrafluorophen-1-yl, di-methylcyclopentadienyl-Ti-bis-2,3 Examples include 4,5,6-pentafluorophen-1-yl, iron-arene complexes described in JP-A-1-304453 and JP-A-1-152109, and the like.

  (G) Examples of hexaarylbiimidazole compounds include JP-B-6-29285, U.S. Pat. Nos. 3,479,185, 4,311,783, and 4,622,286. Various compounds described in each specification, specifically, 2,2′-bis (o-chlorophenyl) -4,4 ′, 5,5′-tetraphenylbiimidazole, 2,2′-bis (o- Bromophenyl)) 4,4 ′, 5,5′-tetraphenylbiimidazole, 2,2′-bis (o, p-dichlorophenyl) -4,4 ′, 5,5′-tetraphenylbiimidazole, 2, 2'-bis (o-chlorophenyl) -4,4 ', 5,5'-tetra (m-methoxyphenyl) biidazole, 2,2'-bis (o, o'-dichlorophenyl) -4,4', 5 , 5'-Tetraphenyl Imidazole, 2,2′-bis (o-nitrophenyl) -4,4 ′, 5,5′-tetraphenylbiimidazole, 2,2′-bis (o-methylphenyl) -4,4 ′, 5 Examples include 5′-tetraphenylbiimidazole, 2,2′-bis (o-trifluorophenyl) -4,4 ′, 5,5′-tetraphenylbiimidazole, and the like.

(H) Examples of the organic borate compound include JP-A-62-143044, JP-A-62-1050242, JP-A-9-188865, JP-A-9-188686, JP-A-9-188710, JP-A-2000-131837, JP-A-2002-107916, JP-A-2766769, JP-A-2002-116539, etc., and Kunz, Martin “Rad Tech'98. Proceeding April 19-22, 1998, Organoborates described in “Chicago” and the like, organoboron sulfonium complexes or organoboron oxosulfonium complexes described in JP-A-6-157623, JP-A-6-175564, and JP-A-6-175561, Japanese Laid-Open Patent Publication No. 6-175554, Japanese Patent Laid-Open No. 6-175553 Organoboron iodonium complexes described in JP-A-9-188710, organoboron phosphonium complexes described in JP-A-9-188710, JP-A-6-348011, JP-A-7-128785, JP-A-7-140589, Specific examples include organoboron transition metal coordination complexes such as Kaihei 7-306527 and JP-A-7-292014.
(I) Examples of the disulfone compound include compounds described in JP-A Nos. 61-166544 and 2003-328465.
(J) Examples of the oxime ester compound include J.M. C. S. Perkin II (1979) P1653-1660), J. MoI. C. S. Perkin II (1979) P156-162, Journal of Photopolymer Science and Technology (1995) P202-232, compounds described in JP-A 2000-66385, compounds described in JP-A 2000-80068, specifically described below Compound etc. are mentioned.

(K) Examples of the onium salt compounds include S.I. I. Schlesinger, Photogr. Sci. Eng. , 18, 387 (1974), T.A. S. Diazonium salts described in Bal et al, Polymer, 21, 423 (1980), ammonium salts described in US Pat. No. 4,069,055, JP-A-4-365049, etc., US Pat. No. 4,069 , 055 and 4,069,056, phosphonium salts described in European Patent Nos. 104 and 143, U.S. Pat. Nos. 339,049 and 410,201, 2-150848, JP-A-2-296514, iodonium salts, European Patent Nos. 370,693, 390,214, 233,567, 297,443, and 297,442 U.S. Pat. Nos. 4,933,377, 161,811, 410,201, 339,049, 4,760,013, 4,73 , 444 No., 2,833,827, German Patent 2,904,626, the 3,604,580 Patent, sulfonium salts described in the specification of Nos. 3,604,581, J. V. Crivello et al, Macromolecules, 10 (6), 1307 (1977), J. MoI. V. Crivello et al, J.A. Polymer
Sci. , Polymer Chem. Ed. , 17, 1047 (1979), a selenonium salt described in C.I. S. Wen et al, Teh, Proc. Conf. Rad. Curing ASIA, p478 Tokyo, Oct (1988), and onium salts such as arsonium salts.
In particular, from the viewpoints of reactivity and stability, the above oxime ester compounds or the diazonium salts, iodonium salts, and sulfonium salts described in detail below are preferable polymerization initiators. In the present invention, these onium salts function not as acid generators but as ionic radical polymerization initiators.
The onium salt suitably used in the present invention is an onium salt represented by the following general formulas (RI-I) to (RI-III).

In General Formula (RI-I), Ar ¹¹ represents an aryl group having 20 or less carbon atoms which may have 1 to 6 substituents, and preferred substituents include an alkyl group having 1 to 12 carbon atoms and a carbon number. 1-12 alkenyl group, C1-C12 alkynyl group, C1-C12 aryl group, C1-C12 alkoxy group, C1-C12 aryloxy group, halogen atom, C1-C1 12 alkylamino groups, C1-C12 dialkylamino groups, C1-C12 alkylamide groups or arylamide groups, carbonyl groups, carboxyl groups, cyano groups, sulfonyl groups, C1-C12 thioalkyl groups And a thioaryl group having 1 to 12 carbon atoms.
Z ₁₁ ⁻ represents a monovalent anion, which is a halogen ion, perchlorate ion, hexafluorophosphate ion, tetrafluoroborate ion, sulfonate ion, sulfinate ion, thiosulfonate ion, sulfate ion, From the surface, perchlorate ion, hexafluorophosphate ion, tetrafluoroborate ion, sulfonate ion, and sulfinate ion are preferable.

In General Formula (RI-II), Ar ²¹ and Ar ²² each independently represent an aryl group having 20 or less carbon atoms which may have 1 to 6 substituents, and preferred substituents have 1 to 12 carbon atoms. Alkyl group, alkenyl group having 1 to 12 carbon atoms, alkynyl group having 1 to 12 carbon atoms, aryl group having 1 to 12 carbon atoms, alkoxy group having 1 to 12 carbon atoms, aryloxy group having 1 to 12 carbon atoms, halogen Atoms, alkylamino groups having 1 to 12 carbon atoms, dialkylamino groups having 1 to 12 carbon atoms, alkylamide groups or arylamide groups having 1 to 12 carbon atoms, carbonyl groups, carboxyl groups, cyano groups, sulfonyl groups, carbon numbers A 1-12 thioalkyl group and a C1-C12 thioaryl group are mentioned.
Z ₂₁ ⁻ represents a monovalent anion, which is a halogen ion, perchlorate ion, hexafluorophosphate ion, tetrafluoroborate ion, sulfonate ion, sulfinate ion, thiosulfonate ion, sulfate ion, From the viewpoint of reactivity, perchlorate ions, hexafluorophosphate ions, tetrafluoroborate ions, sulfonate ions, sulfinate ions, and carboxylate ions are preferable.

In the general formula (RI-III), R ³¹ , R ³² , and R ³³ each independently represents an aryl group having a carbon number of 20 or less, an alkyl group, an alkenyl group, or an alkynyl group that may have 1 to 6 substituents. In view of reactivity and stability, an aryl group is desirable. Preferred substituents are alkyl groups having 1 to 12 carbon atoms, alkenyl groups having 1 to 12 carbon atoms, alkynyl groups having 1 to 12 carbon atoms, aryl groups having 1 to 12 carbon atoms, alkoxy groups having 1 to 12 carbon atoms, Aryloxy group having 1 to 12 carbon atoms, halogen atom, alkylamino group having 1 to 12 carbon atoms, dialkylamino group having 1 to 12 carbon atoms, alkylamide group or arylamide group having 1 to 12 carbon atoms, carbonyl group, carboxyl Group, a cyano group, a sulfonyl group, a thioalkyl group having 1 to 12 carbon atoms, and a thioaryl group having 1 to 12 carbon atoms.
Z ₃₁ ⁻ represents a monovalent anion, which is a halogen ion, perchlorate ion, hexafluorophosphate ion, tetrafluoroborate ion, sulfonate ion, sulfinate ion, thiosulfonate ion, sulfate ion, From the viewpoint of reactivity, perchlorate ions, hexafluorophosphate ions, tetrafluoroborate ions, sulfonate ions, sulfinate ions, and carboxylate ions are preferable, and carboxylate ions described in JP-A-2001-343742 are more preferable. Particularly preferred are carboxylate ions described in JP-A No. 2002-148790.
Examples of onium salts that can be suitably used as a polymerization initiator in the present invention will be given below, but the present invention is not limited thereto.

Among these other polymerization initiators that can be used in combination, from the viewpoint of improving visibility, it is an onium salt, and an inorganic anion such as PF ₆ ⁻ , BF ₄ ⁻ , and C ₄ F ₉ SO ₃ ⁻ as a counter ion. Further, a diaryliodonium salt having two or more electron donating groups is preferable because it is excellent in color development. This initiator is a compound having a diaryliodonium skeleton, and this aryl group is a compound having 2 or more, preferably 3 or more electron donating groups such as an alkyl group and an alkoxy group. The electron donating group is preferably introduced at the para-position and ortho-position of the aryl group of the iodonium salt.

  These other polymerization initiators may be used alone or in combination of two or more. Moreover, these polymerization initiators may be added to the same layer as other components, or another layer may be provided and added thereto.

The total content of the polymerization initiator in the present invention, that is, the total amount of (A) the compound represented by the general formula (1) and the other polymerization initiators that can be used in combination is the total content of the image recording layer. 0.1-50 mass% is preferable with respect to solid content, 0.5-30 mass% is more preferable, It is most preferable that it is a ratio of 1-20 mass%.
The content in the case of using this other polymerization initiator that can be used in combination is preferably 0 to 200 mol% with respect to the compound represented by (A) the general formula (1), and ranges from 0 to 100 mol%. It is preferable that

<(B) Infrared absorber>
When forming an image of the lithographic printing plate precursor according to the present invention with a laser that emits infrared rays of 760 to 1200 nm using a light source, it is usually essential to use an infrared absorber. The infrared absorber is excited by the function of converting the absorbed infrared rays into heat and infrared rays, and transfers electrons to the polymerization initiator (radical generator) containing the compound represented by the above general formula (1) (1). It has the function of transferring energy. The infrared absorber used in the present invention is a dye or pigment having an absorption maximum at a wavelength of 760 to 1200 nm, and an infrared absorbing dye is preferable from the viewpoint of effects.

  As the dye, commercially available dyes and known dyes described in documents such as “Dye Handbook” (edited by the Society for Synthetic Organic Chemistry, published in 1970) can be used. Specifically, dyes such as azo dyes, metal complex azo dyes, pyrazolone azo dyes, naphthoquinone dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinoneimine dyes, methine dyes, cyanine dyes, squarylium dyes, pyrylium salts, metal thiolate complexes, etc. Is mentioned.

  Preferred dyes include, for example, cyanine dyes described in JP-A-58-125246, JP-A-59-84356, JP-A-60-78787, JP-A-58-173696, The methine dyes described in JP-A-58-181690 and JP-A-58-194595, JP-A-58-112793, JP-A-58-224793, JP-A-59-48187, Naphthoquinone dyes described in JP-A-59-73996, JP-A-60-52940, JP-A-60-63744, and the like, squarylium dyes described in JP-A-58-112792, and the like; And cyanine dyes described in British Patent No. 434,875.

Further, near infrared absorption sensitizers described in US Pat. No. 5,156,938 are also preferably used, and substituted arylbenzo (thio) described in US Pat. No. 3,881,924. ) Pyrylium salt, trimethine thiapyrylium salt described in JP-A-57-142645 (US Pat. No. 4,327,169), JP-A-58-181051, 58-220143, 59- No. 41363, No. 59-84248, No. 59-84249, No. 59-146063, No. 59-146061, and Pyrlium compounds described in JP-A-59-216146. And pentamethine thiopyrylium salts described in US Pat. No. 4,283,475, and Japanese Patent Publication Nos. 5-13514 and 5-19702. Pyrylium compounds shown also preferably used. Another preferable example of the dye includes near infrared absorbing dyes described as the formulas (I) and (II) in US Pat. No. 4,756,993.
Other preferable examples of the infrared absorbing dye of the present invention include specific indolenine cyanine dyes described in JP-A-2002-278057 as exemplified below.

  Examples of the pigment used in the present invention include commercially available pigments and color index (CI) manual, “Latest Pigment Handbook” (edited by Japan Pigment Technology Association, published in 1977), “Latest Pigment Application Technology” (CMC Publishing, 1986), “Printing Ink Technology”, CMC Publishing, 1984) can be used.

  Examples of the pigment include black pigments, yellow pigments, orange pigments, brown pigments, red pigments, purple pigments, blue pigments, green pigments, fluorescent pigments, metal powder pigments, and other polymer-bonded dyes. Specifically, insoluble azo pigments, azo lake pigments, condensed azo pigments, chelate azo pigments, phthalocyanine pigments, anthraquinone pigments, perylene and perinone pigments, thioindigo pigments, quinacridone pigments, dioxazine pigments, isoindolinone pigments In addition, quinophthalone pigments, dyed lake pigments, azine pigments, nitroso pigments, nitro pigments, natural pigments, fluorescent pigments, inorganic pigments, carbon black, and the like can be used. Among these pigments, carbon black is preferable.

  These pigments may be used without surface treatment, or may be used after surface treatment. The surface treatment method includes a method of surface coating with a resin or wax, a method of attaching a surfactant, a method of bonding a reactive substance (eg, silane coupling agent, epoxy compound, polyisocyanate, etc.) to the pigment surface, etc. Can be considered. The above-mentioned surface treatment methods are described in “Characteristics and Applications of Metal Soap” (Shobobo), “Printing Ink Technology” (CMC Publishing, 1984) and “Latest Pigment Application Technology” (CMC Publishing, 1986). Yes.

  The particle size of the pigment is preferably in the range of 0.01 μm to 10 μm, more preferably in the range of 0.05 μm to 1 μm, and particularly preferably in the range of 0.1 μm to 1 μm. Within this range, good stability of the pigment dispersion in the image recording layer coating solution and good uniformity of the image recording layer can be obtained.

  As a method for dispersing the pigment, a known dispersion technique used for ink production, toner production or the like can be used. Examples of the disperser include an ultrasonic disperser, a sand mill, an attritor, a pearl mill, a super mill, a ball mill, an impeller, a disperser, a KD mill, a colloid mill, a dynatron, a three-roll mill, and a pressure kneader. Details are described in "Latest Pigment Applied Technology" (CMC Publishing, 1986).

  Among these infrared absorbers, a preferred infrared absorber in the polymerizable composition of the present invention is a cyanine dye. One particularly preferred example is a cyanine dye represented by the following general formula (i).

In formula (i), X ¹ represents a hydrogen atom, a halogen atom, -NPh _2, X ² -L ¹ or a group shown below. Here, X ² represents an oxygen atom, a nitrogen atom, or a sulfur atom, and L ¹ represents a hydrocarbon group having 1 to 12 carbon atoms, an aromatic ring having a hetero atom, or 1 to 1 carbon atom containing a hetero atom. 12 hydrocarbon groups are shown. In addition, a hetero atom here shows a nitrogen atom, a sulfur atom, an oxygen atom, a halogen atom, and a selenium atom. X a ^_- is Z _a which will be described below ^_- has the same definition as, R ^a represents a hydrogen atom, an alkyl group, an aryl group, a substituted or unsubstituted amino group, substituted or unsubstituted amino group and a halogen atom.

R ¹ and R ² each independently represent a hydrocarbon group having 1 to 12 carbon atoms. In view of storage stability of the recording layer coating solution, R ¹ and R ² are preferably hydrocarbon groups having 2 or more carbon atoms, and R ¹ and R ² are bonded to each other to form a 5-membered ring or It is particularly preferable that a 6-membered ring is formed.

Ar ¹ and Ar ² may be the same or different and each represents an aromatic ring or a heteroaromatic ring which may have a substituent. Preferred aromatic rings include a benzene ring and a naphthalene ring. Preferred substituents include a hydrocarbon group having 12 or less carbon atoms, a halogen atom, an alkoxy group having 12 or less carbon atoms, a hydrocarbon group having 12 or less carbon atoms, and 12 carbon atoms. Most preferred are not more than alkoxy groups. Y ¹ and Y ² may be the same or different and each represents a sulfur atom or a dialkylmethylene group having 12 or less carbon atoms. R ³ and R ⁴ may be the same or different and 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 carboxyl group, and a sulfo group, and an alkoxy group having 12 or less carbon atoms is most preferable. R ⁵ , R ⁶ , R ⁷ and R ⁸ may be the same or different and each represents a hydrogen atom or a hydrocarbon group having 12 or less carbon atoms. From the availability of raw materials, a hydrogen atom is preferred. Z _a ⁻ represents a counter anion. However, when the cyanine dye represented by formula (i) has an anionic substituent in the structure thereof, Z _a is does not require charge neutralization ^- is not necessary. Preferred Z _a ⁻ is a halogen ion, a perchlorate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, and a sulfonate ion, particularly preferably a perchlorate ion, from the storage stability of the recording layer coating solution. Tetrafluoroborate ion, hexafluorophosphate ion, and aryl sulfonate ion.
In view of improving visibility, _{Z a} ^- is preferably an anion of an inorganic anion or a strong acid, from this point of _{^{view, PF 6 -, BF 4 -}} , CF 3 SO 3 -, C 4 F ₉ SO ₃ ^- is mentioned, and PF ₆ ^- is most preferable among them.

Specific examples of cyanine dyes represented by formula (i) that can be suitably used in the present invention include those described in paragraph numbers [0017] to [0019] of JP-A No. 2001-133969. Can do.
Further, other particularly preferable examples include specific indolenine cyanine dyes described in JP-A-2002-278057 described above.

  More preferable infrared absorbers in the present invention include cyanine dyes represented by the following general formula (2).

In the formula, Z ¹ and Z ² each independently represent an aromatic ring or a heteroaromatic ring which may have a substituent, and have the same meaning as Ar ¹ and Ar ^{2 in} formula (i). R ³ and R ⁴ each independently represents a hydrocarbon group having 20 or less carbon atoms which may have a substituent, and has the same meaning as R ³ and R ^{4 in} formula (i). R ⁹ and R ¹⁰ each independently represent a hydrogen atom or an alkoxy group which may have a substituent. Za ^- include a counter anion present when charge neutralization is required, the general formula (i) Za ^- synonymous.

  Among these, (B) infrared absorbers that are particularly preferred for the lithographic printing plate precursor according to the invention include compounds having at least one solvent-soluble group on the skeleton of the cyanine dye. The solvent-soluble group in the present invention refers to an organic functional group that can improve the solvent solubility of the infrared absorber, and is not particularly limited as long as it is a functional group having such a function. Oxy group, aryloxy group, alkylcarbonyl group, arylcarbonyl group, alkyloxycarbonyl group, aryloxycarbonyl group, sulfonylamide group, carboxyl group, sulfonyl acid group, hydroxyl group, alkylcarbonyloxy group, arylcarbonyloxy group, and And an amide group. Among these, more preferable solvent-soluble groups include an alkyloxy group, an aryloxy group, an alkyloxycarbonyl group, and an aryloxycarbonyl group. Further, the most preferable solvent-soluble group includes an alkyloxy group and an aryloxy group.

More specifically, (A) the infrared absorber preferably has a cyanine dye structure represented by the general formula (2) and has at least one solvent-soluble group in the molecule. Any of the cyanine dye structures represented by the general formula (2), preferably an aromatic hydrocarbon group represented by Z ¹ or Z ² , R ³ and R ⁴ on the nitrogen atoms at both ends, or —NPh ₂ R ⁹ and R ^{10 in} which a solvent-soluble group is introduced are more preferable. From the viewpoint of improving the on-press developability, it is most preferable to introduce a solvent-soluble group on the nitrogen atoms at both ends. Although the number of solvent-soluble groups to be introduced is at least one, the image recording layer can be applied evenly in a high concentration state, and the residue during on-press development due to the components in the image recording layer can be applied. From the standpoint of suppressing the occurrence of color and improving the on-press developability, it is preferable that 2 to 6 are introduced on one molecule of the cyanine dye.

  Specific examples of the infrared absorbent that can be suitably used in the present invention include, but are not limited to, the following.

  (B) The infrared absorber can be used in combination with other cyan-absorbing dyes and known infrared-absorbing pigments, if necessary, in the cyanine dye. When preparing a lithographic printing plate precursor, Another layer may be provided and added thereto, but the absorbance at the maximum absorption wavelength in the wavelength range of 760 nm to 1200 nm of the image recording layer is in the range of 0.3 to 1.2 by the reflection measurement method. Add as follows. Preferably, it is the range of 0.4-1.1. Within this range, a uniform polymerization reaction proceeds in the depth direction of the image recording layer, and good film strength of the image area and adhesion to the support can be obtained. The absorbance of the image recording layer can be adjusted by the amount of infrared absorber added to the image recording layer and the thickness of the image recording layer. Absorbance can be measured by a conventional method. As a measuring method, for example, on a reflective support such as aluminum, an image recording layer having a thickness appropriately determined in a range in which the coating amount after drying is necessary as a lithographic printing plate is formed, and the reflection density is set to the optical density. And a method of measuring with a spectrophotometer by a reflection method using an integrating sphere.

(B) The amount of the infrared absorber added to the image recording layer is preferably 0.1 to 30% by mass, more preferably 0.5 to 20% by mass in the total solid content. More preferably, 10 mass% is added.

<(C) Compound having at least one ethylenically unsaturated bond capable of addition polymerization>
The image recording layer of the present invention contains (C) a compound having at least one addition-polymerizable ethylenically unsaturated bond (hereinafter, appropriately referred to as a polymerizable compound) in order to perform an efficient curing reaction. Is preferred.
The polymerizable compound that can be used in the present invention is an addition polymerizable compound having at least one ethylenically unsaturated double bond, and is a compound having at least one terminal ethylenically unsaturated bond, preferably two or more. To be elected. Such a compound group is widely known in the industrial field, and can be used without any particular limitation in the present invention. These have chemical forms such as monomers, prepolymers, i.e. dimers, trimers and oligomers, or mixtures thereof and copolymers thereof. Examples of monomers and copolymers thereof include unsaturated carboxylic acids (for example, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid, etc.), and esters and amides thereof. In this case, an ester of an unsaturated carboxylic acid and an aliphatic polyhydric alcohol compound, or an amide of an unsaturated carboxylic acid and an aliphatic polyvalent amine compound is used. In addition, an addition reaction product of an unsaturated carboxylic acid ester or amide having a nucleophilic substituent such as a hydroxyl group, amino group or mercapto group with a monofunctional or polyfunctional isocyanate or epoxy, and monofunctional or polyfunctional A dehydration condensation reaction product with a functional carboxylic acid is also preferably used. Further, an addition reaction product of an unsaturated carboxylic acid ester or amide having an electrophilic substituent such as an epoxy group or an epoxy group with a monofunctional or polyfunctional alcohol, amine or thiol, a halogen group or Also suitable are substitution reaction products of unsaturated carboxylic acid esters or amides having a leaving substituent such as a tosyloxy group with monofunctional or polyfunctional alcohols, amines or thiols. As another example, it is also possible to use a group of compounds substituted with unsaturated phosphonic acid, styrene, vinyl ether or the like instead of the unsaturated carboxylic acid.

  Specific examples of the monomer of an ester of an aliphatic polyhydric alcohol compound and an unsaturated carboxylic acid include acrylic acid esters such as ethylene glycol diacrylate, triethylene glycol diacrylate, 1,3-butanediol diacrylate, and tetramethylene glycol. Diacrylate, propylene glycol diacrylate, neopentyl glycol diacrylate, trimethylolpropane triacrylate, trimethylolpropane tri (acryloyloxypropyl) ether, trimethylolethane triacrylate, hexanediol diacrylate, 1,4-cyclohexanediol diacrylate , Tetraethylene glycol diacrylate, pentaerythritol diacrylate, pentaerythritol triacrylate , Pentaerythritol tetraacrylate, dipentaerythritol diacrylate, dipentaerythritol hexaacrylate, sorbitol triacrylate, sorbitol tetraacrylate, sorbitol pentaacrylate, sorbitol hexaacrylate, tri (acryloyloxyethyl) isocyanurate, polyester acrylate oligomer, isocyanuric acid There are EO-modified triacrylate and the like.

  Methacrylic acid esters include tetramethylene glycol dimethacrylate, triethylene glycol dimethacrylate, neopentyl glycol dimethacrylate, trimethylolpropane trimethacrylate, trimethylolethane trimethacrylate, ethylene glycol dimethacrylate, 1,3-butanediol dimethacrylate, Hexanediol dimethacrylate, pentaerythritol dimethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, dipentaerythritol dimethacrylate, dipentaerythritol hexamethacrylate, sorbitol trimethacrylate, sorbitol tetramethacrylate, bis [p- (3-methacryloxy- 2-hydroxypro ) Phenyl] dimethyl methane, bis - [p- (methacryloxyethoxy) phenyl] dimethyl methane.

  Itaconic acid esters include ethylene glycol diitaconate, propylene glycol diitaconate, 1,3-butanediol diitaconate, 1,4-butanediol diitaconate, tetramethylene glycol diitaconate, pentaerythritol diitaconate And sorbitol tetritaconate. Examples of crotonic acid esters include ethylene glycol dicrotonate, tetramethylene glycol dicrotonate, pentaerythritol dicrotonate, and sorbitol tetradicrotonate. Examples of isocrotonic acid esters include ethylene glycol diisocrotonate, pentaerythritol diisocrotonate, and sorbitol tetraisocrotonate. Examples of maleic acid esters include ethylene glycol dimaleate, triethylene glycol dimaleate, pentaerythritol dimaleate, and sorbitol tetramaleate.

  Examples of other esters include, for example, aliphatic alcohol esters described in JP-B-51-47334 and JP-A-57-196231, JP-A-59-5240, and JP-A-59-5241. And those having an aromatic skeleton described in JP-A-2-226149 and those containing an amino group described in JP-A-1-165613. Furthermore, the ester monomers described above can also be used as a mixture.

  Specific examples of amide monomers of aliphatic polyvalent amine compounds and unsaturated carboxylic acids include methylene bis-acrylamide, methylene bis-methacrylamide, 1,6-hexamethylene bis-acrylamide, 1,6-hexamethylene bis. -Methacrylamide, diethylenetriamine trisacrylamide, xylylene bisacrylamide, xylylene bismethacrylamide and the like. Examples of other preferable amide monomers include those having a cyclohexylene structure described in JP-B No. 54-21726.

  Further, urethane-based addition polymerizable compounds produced using an addition reaction of isocyanate and hydroxyl group are also suitable. Specific examples of such compounds are described in, for example, Japanese Patent Publication No. 48-41708. It contains two or more polymerizable vinyl groups in one molecule obtained by adding a vinyl monomer containing a hydroxyl group represented by the following general formula (ii) to a polyisocyanate compound having two or more isocyanate groups in the molecule. A vinyl urethane compound etc. are mentioned.

^{_{CH 2 = C (R 4)}} COOCH 2 CH (R 5) OH (ii)
(However, R ⁴ and R ⁵ represent H or CH _3. )

  Further, urethane acrylates as described in JP-A-51-37193, JP-B-2-32293, JP-B-2-16765, JP-B-58-49860, JP-B-56-17654 And urethane compounds having an ethylene oxide skeleton described in JP-B-62-39417 and JP-B-62-39418. Furthermore, addition polymerizable compounds having an amino structure or a sulfide structure in the molecule described in JP-A-63-277653, JP-A-63-260909, and JP-A-1-105238 are used. Depending on the case, it is possible to obtain a photopolymerizable composition excellent in the photosensitive speed.

  Other examples include polyester acrylates, epoxy resins and acrylic acid or methacrylic acid described in JP-A-48-64183, JP-B-49-43191, JP-B-52-30490, and JP-B-52-30490. Mention may be made of polyfunctional acrylates and methacrylates such as reacted epoxy acrylates. In addition, JP-B-46-43946, JP-B-1-40337, JP-B-1-40336, specific unsaturated compounds described in each gazette, vinylphosphonic acid compounds described in JP-A-2-25493, and the like are also included. Can be mentioned. In some cases, a structure containing a perfluoroalkyl group described in JP-A-61-22048 is preferably used. Furthermore, Journal of Japan Adhesion Association vol. 20, no. 7, pages 300 to 308 (1984), which are introduced as photocurable monomers and oligomers, can also be used.

About these addition polymerizable compounds, the details of usage, such as the structure, single use or combination, addition amount, etc. can be arbitrarily set according to the performance design of the final lithographic printing plate precursor. For example, it is selected from the following viewpoints.
From the viewpoint of sensitivity, a structure having a large unsaturated group content per molecule is preferable, and in many cases, a bifunctional or higher functionality is preferable. Further, in order to increase the strength of the image area, that is, the cured film, those having three or more functionalities are preferable, and furthermore, different functional numbers and different polymerizable groups (for example, acrylic acid ester, methacrylic acid ester, styrene compound, vinyl ether type). A method of adjusting both sensitivity and strength by using a compound) is also effective.
Further, the selection and use method of the addition polymerization compound is also an important factor for the compatibility and dispersibility with other components (for example, binder polymer, initiator, colorant, etc.) in the image recording layer. In some cases, the compatibility can be improved by using a low-purity compound or by using two or more kinds in combination. In addition, a specific structure may be selected for the purpose of improving the adhesion of the substrate and the protective layer described later.

  (C) The polymerizable compound is preferably used in the range of 5 to 80% by mass, more preferably 25 to 75% by mass, with respect to the nonvolatile component in the image recording layer. These may be used alone or in combination of two or more. In addition, the use method of the addition polymerizable compound can be arbitrarily selected from the viewpoint of polymerization inhibition with respect to oxygen, resolution, fogging, refractive index change, surface adhesiveness, etc. Depending on the case, a layer configuration and coating method such as undercoating and overcoating can be performed.

<(D) Binder polymer>
In the image recording layer according to the present invention, a binder polymer can be further used as necessary for the purpose of improving the film properties of the image recording layer to be formed.
As the binder polymer that can be used in the present invention, a conventionally known binder polymer can be used without limitation, and a linear organic polymer having a film property is preferable. Examples of such binder polymers include acrylic resins, polyvinyl acetal resins, polyurethane resins, polyurea resins, polyimide resins, polyamide resins, epoxy resins, methacrylic resins, polystyrene resins, novolac phenolic resins, polyester resins, and synthetic rubbers. And natural rubber.

  The binder polymer preferably has crosslinkability in order to improve the film strength of the image area. In order to impart crosslinkability to the binder polymer, a crosslinkable functional group such as an ethylenically unsaturated bond may be introduced into the main chain or side chain of the polymer. The crosslinkable functional group may be introduced by copolymerization.

Examples of the polymer having an ethylenically unsaturated bond in the main chain of the molecule include poly-1,4-butadiene and poly-1,4-isoprene.
Examples of polymers having an ethylenically unsaturated bond in the side chain of the molecule are polymers of esters or amides of acrylic acid or methacrylic acid, where the ester or amide residue (-COOR or CONHR R) is ethylene. Examples thereof include polymers having a polymerizable unsaturated bond.

Examples of the residue (the R) having an ethylenically unsaturated _{^{bond, - (CH 2) n CR}} 1 = CR 2 R 3, - (CH 2 O) n CH 2 CR 1 = CR 2 R 3, - _{(CH 2 CH 2 O) n} CH 2 CR 1 = CR 2 R 3, - (CH 2) n NH-CO-O-CH 2 CR 1 = CR 2 R 3, - (CH 2) n -O-CO —CR ¹ ═CR ² R ³ and (CH ₂ CH ₂ O) ₂ —X (wherein R ^{1 to} R ³ are each a hydrogen atom, a halogen atom, or an alkyl group having 1 to 20 carbon atoms, an aryl group, and an alkoxy group. R ¹ and R ² or R ³ may be bonded to each other to form a ring, n represents an integer of 1 to 10. X represents a dicyclopentadienyl residue. Represents a group).

Specific examples of the ester residue include —CH ₂ CH═CH ₂ (described in JP-B-7-21633), —CH ₂ CH ₂ O—CH ₂ CH═CH ₂ , —CH ₂ C. _{(CH 3) = CH 2,} -CH 2 CH = CH-C 6 H 5, -CH 2 CH 2 OCOCH = CH-C 6 H 5, -CH 2 CH 2 -NHCOO-CH 2 CH = CH 2 and CH ₂ CH ₂ O—X (wherein X represents a dicyclopentadienyl residue).
Specific examples of the amide residue include —CH ₂ CH═CH ₂ , —CH ₂ CH ₂ —Y (wherein Y represents a cyclohexene residue), —CH ₂ CH ₂ —OCO—CH═CH _2. Is mentioned.

  The binder polymer having crosslinkability, for example, has a free radical (polymerization initiation radical or a growth radical in the polymerization process of the polymerizable compound) added to the crosslinkable functional group, and the polymerization chain of the polymerizable compound is formed directly between the polymers. Through addition polymerization, a cross-link is formed between the polymer molecules and cured. Alternatively, atoms in the polymer (eg, hydrogen atoms on carbon atoms adjacent to the functional bridging group) are abstracted by free radicals to form polymer radicals that are bonded together, thereby causing cross-linking between polymer molecules. Forms and cures.

  The content of the crosslinkable group in the binder polymer (content of unsaturated double bond capable of radical polymerization by iodine titration) is preferably 0.1 to 10.0 mmol, more preferably 1.0, per 1 g of the binder polymer. -7.0 mmol, most preferably 2.0-5.5 mmol. Within this range, good sensitivity and good storage stability can be obtained.

From the viewpoint of improving the on-press developability, the binder polymer preferably has high solubility or dispersibility in ink and / or fountain solution.
In order to improve solubility or dispersibility in ink, the binder polymer is preferably oleophilic, and in order to improve solubility or dispersibility in dampening water, the binder polymer is hydrophilic. Is preferred. For this reason, in the present invention, it is also effective to use a lipophilic binder polymer and a hydrophilic binder polymer in combination.

  Examples of the hydrophilic binder polymer include hydroxyl group, carboxyl group, carboxylate group, hydroxyethyl group, polyoxyethyl group, hydroxypropyl group, polyoxypropyl group, amino group, aminoethyl group, aminopropyl group, and ammonium. Preferred examples include those having a hydrophilic group such as a group, an amide group, a carboxymethyl group, a sulfo group, or a phosphoric acid group.

  Specific examples include gum arabic, casein, gelatin, starch derivatives, carboxymethylcellulose and its sodium salt, cellulose acetate, sodium alginate, vinyl acetate-maleic acid copolymers, styrene-maleic acid copolymers, polyacrylic acids and their salts, Polymethacrylic acids and their salts, hydroxyethyl methacrylate homopolymers and copolymers, hydroxyethyl acrylate homopolymers and copolymers, hydroxypropyl methacrylate homopolymers and copolymers, hydroxypropyl acrylate homopolymers and copolymers, hydroxybutyl methacrylate homopolymers Polymers and copolymers, homopolymers and copolymers of hydroxybutyl acrylate, polyethylene glycol , Hydroxypropylene polymers, polyvinyl alcohols, hydrolyzed polyvinyl acetate, polyvinyl formal, polyvinyl butyral, polyvinyl pyrrolidone, acrylamide homopolymers and copolymers having a hydrolysis degree of 60 mol% or more, preferably 80 mol% or more Methacrylamide homopolymers and polymers, N-methylolacrylamide homopolymers and copolymers, polyvinylpyrrolidone, alcohol-soluble nylon, polyether of 2,2-bis- (4-hydroxyphenyl) -propane and epichlorohydrin, etc. Is mentioned.

  The binder polymer preferably has a mass average molecular weight of 5,000 or more, more preferably 10,000 to 300,000, and a number average molecular weight of 1,000 or more, preferably 2000 to 250,000. More preferred. The polydispersity (mass average molecular weight / number average molecular weight) is preferably 1.1 to 10.

  The binder polymer may be either a random polymer or a block polymer, but is preferably a random polymer. Moreover, a binder polymer may be used independently or may be used in mixture of 2 or more types.

The binder polymer can be obtained by purchasing a commercial product or synthesizing it by a conventionally known method. Solvents used in the synthesis include, for example, tetrahydrofuran, ethylene dichloride, cyclohexanone, methyl ethyl ketone, acetone, methanol, ethanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, 2-methoxyethyl acetate, diethylene glycol dimethyl ether, 1-methoxy. Examples include 2-propanol, 1-methoxy-2-propyl acetate, N, N-dimethylformamide, N, N-dimethylacetamide, toluene, ethyl acetate, methyl lactate, ethyl lactate, dimethyl sulfoxide, and water. These may be used alone or in combination of two or more.
As the radical polymerization initiator used for synthesizing the binder polymer, known compounds such as an azo initiator and a peroxide initiator can be used.

(D) Content of binder polymer is 0-90 mass% with respect to the total solid of an image recording layer, It is preferable that it is 0-80 mass%, and it is more preferably 0-70 mass%. preferable. Within this range, good image area strength and image formability can be obtained.
Moreover, it is preferable to use (C) polymeric compound and (D) binder polymer in the quantity used as 0.5 / 1-4/1 by mass ratio.

In the image recording layer of the lithographic printing plate precursor according to the present invention, in addition to the above components (A) to (C), and other components such as other polymerization initiators and (D) binder polymers used as desired, As long as the effect is not impaired, various compounds can be contained depending on the purpose.
<Surfactant>
In the present invention, it is preferable to use a surfactant in the image recording layer in order to promote on-press developability at the start of printing and to improve the coated surface state. Examples of the surfactant include nonionic surfactants, anionic surfactants, cationic surfactants, amphoteric surfactants, and fluorosurfactants. Surfactant may be used independently and may be used in combination of 2 or more type.

  The nonionic surfactant used for this invention is not specifically limited, A conventionally well-known thing can be used. For example, polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene polystyryl phenyl ethers, polyoxyethylene polyoxypropylene alkyl ethers, glycerin fatty acid partial esters, sorbitan fatty acid partial esters, pentaerythritol Fatty acid partial esters, propylene glycol mono fatty acid esters, sucrose fatty acid partial esters, polyoxyethylene sorbitan fatty acid partial esters, polyoxyethylene sorbitol fatty acid partial esters, polyethylene glycol fatty acid esters, polyglycerin fatty acid partial esters, Polyoxyethylenated castor oil, polyoxyethylene glycerin fatty acid partial esters, fatty acid diethanolamides, N N- bis-2-hydroxyalkylamines, polyoxyethylene alkylamines, triethanolamine fatty acid ester, trialkylamine oxide, polyethylene glycol, copolymers of polyethylene glycol and polypropylene glycol.

  The anionic surfactant used in the present invention is not particularly limited, and conventionally known anionic surfactants can be used. For example, fatty acid salts, abietic acid salts, hydroxyalkane sulfonates, alkane sulfonates, dialkyl sulfosuccinate esters, linear alkyl benzene sulfonates, branched alkyl benzene sulfonates, alkyl naphthalene sulfonates, alkyl phenoxy poly Oxyethylene propyl sulfonates, polyoxyethylene alkyl sulfophenyl ether salts, N-methyl-N-oleyl taurine sodium salt, N-alkyl sulfosuccinic acid monoamide disodium salt, petroleum sulfonates, sulfated beef oil, fatty acid alkyl esters Sulfates, alkyl sulfates, polyoxyethylene alkyl ether sulfates, fatty acid monoglyceride sulfates, polyoxyethylene alcohol Ruphenyl ether sulfates, polyoxyethylene styryl phenyl ether sulfates, alkyl phosphates, polyoxyethylene alkyl ether phosphates, polyoxyethylene alkyl phenyl ether phosphates, styrene / maleic anhydride Examples thereof include partial saponification products of polymers, partial saponification products of olefin / maleic anhydride copolymers, and naphthalene sulfonate formalin condensates.

The cationic surfactant used in the present invention is not particularly limited, and conventionally known cationic surfactants can be used. Examples thereof include alkylamine salts, quaternary ammonium salts, polyoxyethylene alkylamine salts, and polyethylene polyamine derivatives.
The amphoteric surfactant used in the present invention is not particularly limited, and conventionally known amphoteric surfactants can be used. Examples thereof include carboxybetaines, aminocarboxylic acids, sulfobetaines, aminosulfuric esters, and imidazolines.

  Among the above surfactants, those having “polyoxyethylene” can be read as “polyoxyalkylene” such as polyoxymethylene, polyoxypropylene, polyoxybutylene, etc. These surfactants can also be used.

  More preferable surfactants include fluorine-based surfactants containing a perfluoroalkyl group in the molecule. Examples of such fluorosurfactants include anionic types such as perfluoroalkyl carboxylates, perfluoroalkyl sulfonates, and perfluoroalkyl phosphates; amphoteric types such as perfluoroalkyl betaines; Cation type such as trimethylammonium salt; perfluoroalkylamine oxide, perfluoroalkylethylene oxide adduct, oligomer containing perfluoroalkyl group and hydrophilic group, oligomer containing perfluoroalkyl group and lipophilic group, perfluoroalkyl Nonionic types such as an oligomer containing a group, a hydrophilic group and a lipophilic group, and a urethane containing a perfluoroalkyl group and a lipophilic group. Moreover, the fluorine-type surfactant described in each gazette of Unexamined-Japanese-Patent No. 62-170950, 62-226143, and 60-168144 is also mentioned suitably.

Surfactant can be used individually or in combination of 2 or more types.
The content of the surfactant is preferably 0.001 to 10% by mass, and more preferably 0.01 to 7% by mass, based on the total solid content of the image recording layer.

<Colorant>
In the present invention, various compounds other than these may be added as necessary. For example, a dye having a large absorption in the visible light region can be used as an image colorant. Specifically, Oil Yellow # 101, Oil Yellow # 103, Oil Pink # 312, Oil Green BG, Oil Blue BOS, Oil Blue # 603, Oil Black BY, Oil Black BS, Oil Black T-505 (orientated chemistry) Kogyo Co., Ltd.), Victoria Pure Blue, Crystal Violet (CI42555), Methyl Violet (CI42535), Ethyl Violet, Rhodamine B (CI145170B), Malachite Green (CI42000), Methylene Blue (CI522015), etc., and JP-A-62-2 And dyes described in No. 293247. Also, pigments such as phthalocyanine pigments, azo pigments, carbon black, titanium oxide, etc. can be suitably used.

  These colorants are preferably added since it is easy to distinguish an image area from a non-image area after image formation. The addition amount is 0.01 to 10% by mass with respect to the total solid content of the image recording material.

<Bakeout agent>
In the image recording layer of the present invention, a compound that changes color by an acid or a radical can be added in order to produce a printout image.
In the present invention, an image having excellent visibility in the exposed region is formed by the synergistic effect of the compound (A) represented by the general formula (1) and the infrared absorber (B). A baking-out agent is not always necessary, but can be used in combination for the purpose of improving visibility.
Examples of compounds that can be used for this purpose include various dyes such as diphenylmethane, triphenylmethane, thiazine, oxazine, xanthene, anthraquinone, iminoquinone, azo, and azomethine.

  Specific examples include brilliant green, ethyl violet, methyl green, crystal violet, basic fuchsin, methyl violet 2B, quinaldine red, rose bengal, methanyl yellow, thymol sulfophthalein, xylenol blue, methyl orange, paramethyl red, Congo Fred, Benzopurpurin 4B, α-Naphthyl Red, Nile Blue 2B, Nile Blue A, Methyl Violet, Malachide Green, Parafuchsin, Victoria Pure Blue BOH [made by Hodogaya Chemical Co., Ltd.], Oil Blue # 603 Kogyo Co., Ltd.], Oil Pink # 312 [Orient Chemical Co., Ltd.], Oil Red 5B [Orient Chemical Co., Ltd.], Oil Scarlet # 308 [Orient Gaku Kogyo Co., Ltd.], Oil Red OG [Orient Chemical Co., Ltd.], Oil Red RR [Orient Chemical Co., Ltd.], Oil Green # 502 [Orient Chemical Co., Ltd.], Spiron Red BEH Special [made by Hodogaya Chemical Co., Ltd.], m-cresol purple, cresol red, rhodamine B, rhodamine 6G, sulforhodamine B, auramine, 4-p-diethylaminophenyliminonaphthoquinone, 2-carboxyanilino-4-p- Diethylaminophenyliminonaphthoquinone, 2-carboxystearylamino-4-pN, N-bis (hydroxyethyl) amino-phenyliminonaphthoquinone, 1-phenyl-3-methyl-4-p-diethylaminophenylimino-5-pyrazolone, 1-β-naphthyl-4- - dyes and p of diethylamino phenyl imino-5-pyrazolone, p ', p "- hexamethyl triamnotriphenylmethane (leuco crystal violet), and a leuco dye such as Pergascript Blue SRB (manufactured by Ciba-Geigy).

  In addition to the above, a leuco dye known as a material for thermal paper or pressure-sensitive paper is also suitable. Specific examples include crystal violet lactone, malachite green lactone, benzoylleucomethylene blue, 2- (N-phenyl-N-methylamino) -6- (Np-tolyl-N-ethyl) amino-fluorane, 2-anilino. -3-methyl-6- (N-ethyl-p-toluidino) fluorane, 3,6-dimethoxyfluorane, 3- (N, N-diethylamino) -5-methyl-7- (N, N-dibenzylamino) ) -Fluorane, 3- (N-cyclohexyl-N-methylamino) -6-methyl-7-anilinofluorane, 3- (N, N-diethylamino) -6-methyl-7-anilinofluorane, 3 -(N, N-diethylamino) -6-methyl-7-xylidinofluorane, 3- (N, N-diethylamino) -6-methyl-7-chloro Fluorane, 3- (N, N-diethylamino) -6-methoxy-7-aminofluorane, 3- (N, N-diethylamino) -7- (4-chloroanilino) fluorane, 3- (N, N-diethylamino) -7-chlorofluorane, 3- (N, N-diethylamino) -7-benzylaminofluorane, 3- (N, N-diethylamino) -7,8-benzofluorane, 3- (N, N-dibutyl) Amino) -6-methyl-7-anilinofluorane, 3- (N, N-dibutylamino) -6-methyl-7-xylidinofluorane, 3-piperidino-6-methyl-7-anilinofluorane 3-pyrrolidino-6-methyl-7-anilinofluorane, 3,3-bis (1-ethyl-2-methylindol-3-yl) phthalide, 3,3-bis (1-n-butyl- -Methylindol-3-yl) phthalide, 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3- (4-diethylamino-2-ethoxyphenyl) -3- (1-ethyl- 2-methylindol-3-yl) -4-zaphthalide, 3- (4-diethylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) phthalide, and the like.

  A suitable addition amount of the dye that changes color by an acid or a radical is 0.01 to 10% by mass with respect to the solid content of the image recording layer.

<Polymerization inhibitor>
In order to prevent unnecessary thermal polymerization of the polymerizable compound (C) during the production or storage of the image recording layer, a small amount of a thermal polymerization inhibitor is preferably added to the image recording layer of the present invention.
Examples of the thermal polymerization inhibitor include hydroquinone, p-methoxyphenol, di-t-butyl-p-cresol, pyrogallol, t-butylcatechol, benzoquinone, 4,4′-thiobis (3-methyl-6-t- (Butylphenol), 2,2′-methylenebis (4-methyl-6-tert-butylphenol), N-nitroso-N-phenylhydroxylamine aluminum salt are preferred.
The addition amount of the thermal polymerization inhibitor is preferably about 0.01 to about 5% by mass with respect to the total solid content of the image recording layer.

<Higher fatty acid derivatives, etc.>
In order to prevent polymerization inhibition by oxygen, a higher fatty acid derivative such as behenic acid or behenic acid amide is added to the image recording layer of the present invention, and the surface of the image recording layer is dried during the coating process. It may be unevenly distributed. The amount of the higher fatty acid derivative added is preferably about 0.1 to about 10% by mass with respect to the total solid content of the image recording layer.

<Plasticizer>
The image recording layer of the present invention may contain a plasticizer in order to improve the on-press developability.
Examples of the plasticizer include phthalates such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate, diisobutyl phthalate, dioctyl phthalate, octyl capryl phthalate, dicyclohexyl phthalate, ditridecyl phthalate, butyl benzyl phthalate, diisodecyl phthalate, diallyl phthalate; Glycol esters such as glycol phthalate, ethyl phthalyl ethyl glycolate, methyl phthalyl ethyl glycolate, butyl phthalyl butyl glycolate, triethylene glycol dicaprylate; Phosphate esters such as tricresyl phosphate and triphenyl phosphate Diisobutyl adipate, dioctyl adipate, dimethyl sebacate, dibutyl sebacate, dioct Ruazereto, aliphatic dibasic acid esters such as dibutyl maleate; polyglycidyl methacrylate, triethyl citrate, glycerin triacetyl ester, butyl laurate in.
The plasticizer content is preferably about 30% by mass or less based on the total solid content of the image recording layer.

<Inorganic fine particles>
The image recording layer of the present invention may contain inorganic fine particles for the purpose of improving the strength of the cured film in the image area and improving the on-press developability of the non-image area.
As the inorganic fine particles, for example, silica, alumina, magnesium oxide, titanium oxide, magnesium carbonate, calcium alginate, or a mixture thereof is preferably exemplified. Even if they are not photothermally convertible, they can be used for strengthening the film, enhancing interfacial adhesion by surface roughening, and the like.
The inorganic fine particles preferably have an average particle size of 5 nm to 10 μm, and more preferably 0.5 to 3 μm. Within the above range, it is possible to form a non-image portion having excellent hydrophilicity, which is stably dispersed in the image recording layer, sufficiently retains the film strength of the image recording layer, and hardly causes stains during printing.
The inorganic fine particles as described above can be easily obtained as a commercial product such as a colloidal silica dispersion.
The content of the inorganic fine particles is preferably 20% by mass or less, and more preferably 10% by mass or less, based on the total solid content of the image recording layer.

<Low molecular hydrophilic compound>
The image recording layer of the present invention may contain a hydrophilic low molecular weight compound for improving on-press developability. Examples of the hydrophilic low-molecular compound include water-soluble organic compounds such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol and the like, and ether or ester derivatives thereof, glycerin, Polyhydroxys such as pentaerythritol, organic amines such as triethanolamine and diethanolamine monoethanolamine and salts thereof, organic sulfonic acids such as toluenesulfonic acid and benzenesulfonic acid and salts thereof, organic phosphonic acids such as phenylphosphonic acid and the like Examples thereof include organic carboxylic acids such as salts thereof, tartaric acid, oxalic acid, citric acid, malic acid, lactic acid, gluconic acid and amino acids, and salts thereof.

<(E) Microcapsule / Microgel>
In the present invention, several modes can be used as a method for incorporating the above-mentioned image recording layer constituent components (A) to (D) and the above-mentioned other constituent components into the image recording layer. One is a molecular dispersion type image recording layer in which the constituent components are dissolved and applied in an appropriate solvent as described in, for example, JP-A-2002-287334. In another embodiment, for example, as described in JP-A-2001-277740 and JP-A-2001-277742, all or part of the constituent components are encapsulated in microcapsules and contained in the image recording layer. It is a microcapsule type image recording layer. Further, in the microcapsule type image recording layer, the constituent component can be contained outside the microcapsule. Here, it is preferable that the microcapsule-type image recording layer includes a hydrophobic constituent component in the microcapsule and a hydrophilic constituent component outside the microcapsule. As still another embodiment, an embodiment in which the image recording layer contains crosslinked resin particles, that is, microgel, can be mentioned. The microgel may contain a part of the constituent component in and / or on the surface thereof. In particular, an embodiment in which a reactive microgel is formed by having a polymerizable compound on the surface thereof is particularly preferable from the viewpoint of image formation sensitivity and printing durability.
In order to obtain better on-press developability, the image recording layer is preferably a microcapsule type or microgel type image recording layer.

As a method for microencapsulating or microgelling the image recording layer constituent components, known methods can be applied.
For example, as a method for producing microcapsules, US Pat. No. 2,800,547, US Pat. No. 2,800,498, a method using coacervation, US Pat. No. 3,287,154, Japanese Patent Publication No. 38-19574, The method by the interfacial polymerization method found in US Pat. No. 42-446, the method by the precipitation of polymer found in US Pat. Nos. 3,418,250 and 3,660,304, the isocyanate found in US Pat. No. 3,796,669 Method using polyol wall material, method using isocyanate wall material found in US Pat. No. 3,914,511, urea found in US Pat. Nos. 4,001,140, 4,087,376 and 4,089,802 -Formaldehyde or urea formaldehyde A method using a resorcinol-based wall forming material, a method using a wall material such as melamine-formaldehyde resin, hydroxycellulose, etc. found in US Pat. No. 4,025,445, and Japanese Patent Publication Nos. 36-9163 and 51-9079. In situ method by monomer polymerization, spraying method found in British Patent No. 930422, US Pat. No. 3,111,407, electrolytic dispersion cooling seen in British Patent Nos. 952807 and 967074 There are laws, but it is not limited to these.

  A preferable microcapsule wall used in the present invention has a three-dimensional cross-linking and has a property of swelling with a solvent. From such a viewpoint, the wall material of the microcapsule is preferably polyurea, polyurethane, polyester, polycarbonate, polyamide, and a mixture thereof, and particularly preferably polyurea and polyurethane. Further, a compound having a crosslinkable functional group such as an ethylenically unsaturated bond capable of introducing a binder polymer may be introduced into the microcapsule wall.

On the other hand, as a method for preparing the microgel, granulation by interfacial polymerization described in JP-B-38-19574 and JP-A-42-446, non-patent document as described in JP-A-5-61214, and the like. Granulation by aqueous dispersion polymerization can be used. However, it is not limited to these methods.
As the method using the interfacial polymerization, the known microcapsule production method described above can be applied.

  Preferred microgels used in the present invention are those granulated by interfacial polymerization and having three-dimensional crosslinking. From such a viewpoint, the material to be used is preferably polyurea, polyurethane, polyester, polycarbonate, polyamide, and a mixture thereof, and polyurea and polyurethane are particularly preferable.

  The average particle size of the microcapsules or microgel is preferably 0.01 to 3.0 μm. 0.05-2.0 micrometers is further more preferable, and 0.10-1.0 micrometer is especially preferable. Within this range, good resolution and stability over time can be obtained.

(Formation of image recording layer)
The image recording layer according to the present invention is formed by preparing or coating an image recording layer coating solution by dissolving or dispersing the necessary components in a solvent and applying the solution onto an appropriate support. Solvents used here include ethylene dichloride, cyclohexanone, methyl ethyl ketone, methanol, ethanol, propanol, ethylene glycol monomethyl ether, 1-methoxy-2-propanol, 2-methoxyethyl acetate, 1-methoxy-2-propyl acetate, dimethoxy Examples include ethane, methyl lactate, ethyl lactate, N, N-dimethylacetamide, N, N-dimethylformamide, tetramethylurea, N-methylpyrrolidone, dimethyl sulfoxide, sulfolane, γ-butyrolactone, toluene, water and the like. However, the present invention is not limited to this.
These solvents are used alone or in combination. The solid content concentration of the coating solution is preferably 1 to 50% by mass.
The image recording layer of the present invention can be formed by preparing a plurality of coating solutions in which the same or different components are dispersed or dissolved in the same or different solvents, and repeating a plurality of coatings and dryings.

The image recording layer coating amount (solid content) on the support obtained after coating and drying varies depending on the use, but is generally preferably 0.3 to 3.0 g / m ² . Within this range, good sensitivity and good film characteristics of the image recording layer can be obtained.
Various methods can be used as a coating method. Examples thereof include bar coater coating, spin coating, spray coating, curtain coating, dip coating, air knife coating, blade coating, and roll coating.

[Support]
The support used for the lithographic printing plate precursor according to the invention is not particularly limited as long as it is a dimensionally stable plate-like material. For example, paper, paper laminated with plastic (eg, polyethylene, polypropylene, polystyrene, etc.), metal plate (eg, aluminum, zinc, copper, etc.), plastic film (eg, cellulose diacetate, cellulose triacetate, cellulose propionate) Cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, etc.), and paper or plastic films on which the above-mentioned metals are laminated or deposited. A preferable support includes a polyester film and an aluminum plate. Among these, an aluminum plate that has good dimensional stability and is relatively inexpensive is preferable.

  The aluminum plate is a pure aluminum plate, an alloy plate containing aluminum as a main component and containing a trace amount of foreign elements, or a plastic laminated on a thin film of aluminum or an aluminum alloy. Examples of foreign elements contained in the aluminum alloy include silicon, iron, manganese, copper, magnesium, chromium, zinc, bismuth, nickel, and titanium. The content of foreign elements in the alloy is preferably 10% by mass or less. In the present invention, a pure aluminum plate is preferable, but completely pure aluminum is difficult to manufacture in terms of refining technology, and therefore may contain a slightly different element. The composition of the aluminum plate is not specified, and a publicly known material can be used as appropriate.

  The thickness of the support is preferably 0.1 to 0.6 mm, more preferably 0.15 to 0.4 mm, and still more preferably 0.2 to 0.3 mm.

  Prior to using the aluminum plate, it is preferable to perform a surface treatment such as roughening treatment or anodizing treatment. By the surface treatment, it is easy to improve hydrophilicity and secure adhesion between the image recording layer and the support. Prior to roughening the aluminum plate, a degreasing treatment with a surfactant, an organic solvent, an alkaline aqueous solution or the like for removing rolling oil on the surface is performed as desired.

The surface roughening treatment of the aluminum plate is performed by various methods. For example, mechanical surface roughening treatment, electrochemical surface roughening treatment (surface roughening treatment for dissolving the surface electrochemically), chemical treatment, etc. Surface roughening treatment (roughening treatment that chemically selectively dissolves the surface).
As a method for the mechanical surface roughening treatment, a known method such as a ball polishing method, a brush polishing method, a blast polishing method, or a buff polishing method can be used.
Examples of the electrochemical surface roughening treatment include a method in which an alternating current or a direct current is used in an electrolytic solution containing an acid such as hydrochloric acid or nitric acid. Another example is a method using a mixed acid as described in JP-A-54-63902.

  The surface-roughened aluminum plate is subjected to an alkali etching treatment using an aqueous solution of potassium hydroxide, sodium hydroxide or the like, if necessary, further neutralized, and if desired, wear resistant. In order to increase the anodic oxidation treatment.

As the electrolyte used for the anodizing treatment of the aluminum plate, various electrolytes that form a porous oxide film can be used. In general, sulfuric acid, hydrochloric acid, oxalic acid, chromic acid or a mixed acid thereof is used. The concentration of these electrolytes is appropriately determined depending on the type of electrolyte.
The conditions for anodizing treatment vary depending on the electrolyte used and cannot be specified in general. In general, however, the electrolyte concentration is 1 to 80% by mass solution, the liquid temperature is 5 to 70 ° C., and the current density is 5 to 60 A / day. dm ² , voltage 1 to 100 V, and electrolysis time 10 seconds to 5 minutes are preferable. The amount of the anodized film formed is preferably from 1.0 to 5.0 g / ^{m 2,} and more preferably 1.5 to 4.0 g / ^{m 2.} Within this range, good printing durability and good scratch resistance of the non-image area of the lithographic printing plate can be obtained.

  After the anodizing treatment, the surface of the aluminum plate is subjected to a hydrophilic treatment as necessary. The hydrophilization treatment is described in US Pat. Nos. 2,714,066, 3,181,461, 3,280,734, and 3,902,734. There are such alkali metal silicate methods. In this method, the support is immersed in an aqueous solution such as sodium silicate or electrolytically treated. In addition, the treatment with potassium zirconate fluoride described in JP-B 36-22063, U.S. Pat. Nos. 3,276,868, 4,153,461 and 4,689, And a method of treating with polyvinylphosphonic acid as described in each specification of No.272.

The support preferably has a center line average roughness of 0.10 to 1.2 μm. Within this range, good adhesion to the image recording layer, good printing durability and good stain resistance can be obtained.
The color density of the support is preferably 0.15 to 0.65 as the reflection density value. Within this range, good image formability by preventing halation during image exposure and good plate inspection after development can be obtained.

[Back coat layer]
After the surface treatment is performed on the support or after the undercoat layer is formed, a backcoat layer can be provided on the back surface of the support, if necessary.
Examples of the back coat layer include hydrolysis and polycondensation of organic polymer compounds described in JP-A-5-45885, organic metal compounds or inorganic metal compounds described in JP-A-6-35174, and the like. Preferable examples include a coating layer made of a metal oxide. Of these, the use of silicon alkoxy compounds such as Si (OCH ₃ ) ₄ , Si (OC ₂ H ₅ ) ₄ , Si (OC ₃ H ₇ ) ₄ , Si (OC ₄ H ₉ ) ₄ is inexpensive. It is preferable in that it is easily available.

(Undercoat layer)
In the lithographic printing plate precursor according to the invention, an undercoat layer can be provided between the image recording layer and the support, if necessary, particularly in the case of an on-press development type lithographic printing plate precursor. Since the undercoat layer tends to cause the image recording layer to peel off from the support in the unexposed area, the on-press developability is improved. In addition, in the case of infrared laser exposure, since the undercoat layer functions as a heat insulating layer, the heat generated by the exposure does not diffuse to the support and can be used efficiently, so that the sensitivity can be increased. There is.
Specific examples of the undercoat layer compound (undercoat compound) include silane coupling agents having an addition-polymerizable ethylenic double bond reactive group described in JP-A-10-282679, Preferable examples include phosphorus compounds having an ethylenic double bond reactive group described in Kaihei 2-304441.
The most preferable undercoat compound includes a polymer resin obtained by copolymerizing a monomer having an adsorptive group, a monomer having a hydrophilic group, and a monomer having a crosslinkable group.

An essential component of the undercoat polymer resin is an adsorptive group on the hydrophilic support surface. The presence or absence of adsorptivity on the surface of the hydrophilic support can be determined by the following method, for example.
A coating night is prepared by dissolving the test compound in a readily soluble solvent, and the coating night is coated and dried on the support so that the coating amount after drying is 30 mg / m ² . Next, the support coated with the test compound is sufficiently washed with a readily soluble solvent, and then the residual amount of the test compound that has not been removed by washing is measured to calculate the adsorbed amount of the support. Here, the measurement of the remaining amount may be performed by directly quantifying the amount of the remaining compound or by quantifying the amount of the test compound dissolved in the cleaning liquid. The compound can be quantified by, for example, fluorescent X-ray measurement, reflection spectral absorbance measurement, liquid chromatography measurement and the like. The compound having support adsorptivity is a compound that remains at 1 mg / m ² or more even after the above-described washing treatment.

The adsorptive group on the surface of the hydrophilic support is a substance (for example, metal, metal oxide) or a functional group (for example, hydroxyl group) existing on the surface of the hydrophilic support and a chemical bond (for example, ionic bond, hydrogen). Bond, coordination bond, bond by intermolecular force). The adsorptive group is preferably an acid group or a cationic group.
The acid group preferably has an acid dissociation constant (pKa) of 7 or less. Examples of the acid group include a phenolic hydroxyl group, a carboxyl _{group, -SO 3 H, -OSO 3 H} , -PO 3 H 2, -OPO 3 H 2, -CONHSO 2 -, - SO 2 NHSO 2 - and COCH ₂ COCH ₃ is included. Among them -OPO ₃ H ₂ and _PO 3 _{H 2} are particularly preferred. These acid groups may be metal salts.
The cationic group is preferably an onium group. Examples of the onium group include an ammonium group, a phosphonium group, an arsonium group, a stibonium group, an oxonium group, a sulfonium group, a selenonium group, a stannonium group, and an iodonium group. An ammonium group, a phosphonium group and a sulfonium group are preferred, an ammonium group and a phosphonium group are more preferred, and an ammonium group is most preferred.

  Particularly preferred examples of the monomer having an adsorptive group include compounds represented by the following formula (iii) or (iv).

In the above formula, R ¹ , R ² and R ³ are each independently a hydrogen atom, a halogen atom or an alkyl group having 1 to 6 carbon atoms. R ¹ , R ² and R ³ are each independently preferably a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. More preferred is a hydrogen atom or a methyl group. R ² and R ³ are particularly preferably a hydrogen atom. Z is a functional group that adsorbs to the surface of the hydrophilic support.
In the formula (iii), X is an oxygen atom (—O—) or imino (—NH—). X is more preferably an oxygen atom. In the formula (iii), L is a divalent linking group. L is a divalent aliphatic group (alkylene group, substituted alkylene group, alkenylene group, substituted alkenylene group, alkynylene group, substituted alkynylene group), divalent aromatic group (arylene group, substituted arylene group) or divalent A heterocyclic group, or an oxygen atom (—O—), a sulfur atom (—S—), an imino (—NH—), a substituted imino (—NR—, R is an aliphatic group, an aromatic group; Or a heterocyclic group) or a combination with carbonyl (—CO—).
The aliphatic group may have a cyclic structure or a branched structure. The number of carbon atoms in the aliphatic group is preferably 1 to 20, more preferably 1 to 15, and most preferably 1 to 10. The aliphatic group is preferably a saturated aliphatic group rather than an unsaturated aliphatic group. The aliphatic group may have a substituent. Examples of the substituent include a halogen atom, a hydroxyl group, an aromatic group, and a heterocyclic group.
The number of carbon atoms in the aromatic group is preferably 6 to 20, more preferably 6 to 15, and most preferably 6 to 10. The aromatic group may have a substituent. Examples of the substituent include a halogen atom, a hydroxyl group, an aliphatic group, an aromatic group, and a heterocyclic group.
The heterocyclic group preferably has a 5-membered or 6-membered ring as the heterocycle. The hetero ring may be condensed with another hetero ring, an aliphatic ring or an aromatic ring. The heterocyclic group may have a substituent. Examples of substituents include halogen atoms, hydroxyl groups, oxo groups (═O), thioxo groups (═S), imino groups (═NH), substituted imino groups (═N—R, R is an aliphatic group, aromatic Group or heterocyclic group), aliphatic group, aromatic group and heterocyclic group.
L is preferably a divalent linking group containing a plurality of polyoxyalkylene structures. The polyoxyalkylene structure is more preferably a polyoxyethylene structure. In other words, L preferably contains — (OCH ₂ CH ₂ ) _n — (n is an integer of 2 or more).
In the formula (iv), Y is a carbon atom or a nitrogen atom. When Y is a nitrogen atom and L is connected to Y to form a quaternary pyridinium group, Z itself is adsorbable, so Z is not essential, and Z may be a hydrogen atom. L represents the same divalent linking group or single bond as in formula (iii).

The adsorptive functional group is as described above.
Examples of typical compounds represented by formula (iii) or (iv) are shown below.

Examples of the hydrophilic group of the undercoat polymer resin that can be used in the present invention include a hydroxyl group, a carboxyl group, a carboxylate group, a hydroxyethyl group, a polyoxyethyl group, a hydroxypropyl group, a polyoxypropyl group, and an amino group. Preferred examples include a group, aminoethyl group, aminopropyl group, ammonium group, amide group, carboxymethyl group, sulfo group, and phosphate group. Among these, a monomer having a sulfo group exhibiting high hydrophilicity is preferable. Specific examples of the monomer having a sulfo group include methallyloxybenzenesulfonic acid, allyloxybenzenesulfonic acid, allylsulfonic acid, vinylsulfonic acid, p-styrenesulfonic acid, methallylsulfonic acid, acrylamide t-butylsulfonic acid, Examples include 2-acrylamido-2-methylpropanesulfonic acid, (3-acryloyloxypropyl) butylsulfonic acid sodium salt, and amine salt. Of these, 2-acrylamido-2-methylpropanesulfonic acid sodium salt is preferred in view of hydrophilic performance and handling of synthesis.

  The polymer resin for the undercoat layer of the present invention preferably has a crosslinkable group. The crosslinkable group can improve the adhesion with the image area. In order to make the polymer resin for the undercoat layer crosslinkable, a crosslinkable functional group such as an ethylenically unsaturated bond is introduced into the side chain of the polymer, or the polar substituent of the polymer resin is countercharged. Or a compound having an ethylenically unsaturated bond may be introduced by forming a salt structure.

  Examples of polymers having an ethylenically unsaturated bond in the side chain of the molecule are polymers of esters or amides of acrylic acid or methacrylic acid, where the ester or amide residue (R of -COOR or CONHR) is ethylene. Examples thereof include polymers having a polymerizable unsaturated bond.

Examples of the residue (the R) having an ethylenically unsaturated _{bond, - (CH 2) n CR} 1 = CR 2 R 3, - (CH 2 O) n CH 2 CR 1 = CR 2 R 3, - _{(CH 2 CH 2 O) n} CH 2 CR 1 = CR 2 R 3, - (CH 2) n NH-CO-O-CH 2 CR 1 = CR 2 R 3, - (CH 2) n -O-CO -CR ₁ = _CR 2 _{R 3,} and _(CH 2 CH ₂ O) in ₂ -X _(wherein, R 1 to R ₃ are each a hydrogen atom, a halogen atom or an alkyl group having 1 to 20 carbon atoms, an aryl group, Represents an alkoxy group or an aryloxy group, and R ₁ and R ₂ or R ₃ may combine with each other to form a ring, n represents an integer of 1 to 10. X represents dicyclopentadienyl. Represents a residue).
Specific examples of the ester residue include —CH ₂ CH═CH ₂ (described in JP-B-7-21633), —CH ₂ CH ₂ O—CH ₂ CH═CH ₂ , —CH ₂ C. _{(CH 3) = CH 2,} -CH 2 CH = CH-C 6 H 5, -CH 2 CH 2 OCOCH = CH-C 6 H 5, -CH 2 CH 2 NHCOO-CH 2 CH = CH 2, and CH ₂ CH ₂ O—X (wherein X represents a dicyclopentadienyl residue).
Specific examples of the amide residue include —CH ₂ CH═CH ₂ , —CH ₂ CH ₂ O—Y (wherein Y represents a cyclohexene residue), —CH ₂ CH ₂ OCO—CH═CH _2. Is mentioned.
As the monomer having a crosslinkable group of the polymer resin for the undercoat layer, an ester or amide of acrylic acid or methacrylic acid having the crosslinkable group is preferable.

  The content of the crosslinkable group in the polymer resin for the undercoat layer (content of unsaturated double bond capable of radical polymerization by iodine titration) is preferably 0.1 to 10.0 mmol per 1 g of the polymer resin. Preferably it is 1.0-7.0 mmol, Most preferably, it is 2.0-5.5 mmol. Within this range, both good sensitivity and dirtiness and good storage stability can be obtained.

The polymer resin for the undercoat layer preferably has a mass average molecular weight of 5000 or more, more preferably 10,000 to 300,000, and a number average molecular weight of 1000 or more, preferably 2000 to 25 More preferably, it is 10,000. The polydispersity (mass average molecular weight / number average molecular weight) is preferably 1.1 to 10.
The polymer resin for the undercoat layer may be any of a random polymer, a block polymer, a graft polymer, and the like, but is preferably a random polymer.

The undercoat polymer resin may be used alone or in combination of two or more. The undercoat layer coating solution is obtained by dissolving the above-described undercoat polymer in an organic solvent (for example, methanol, ethanol, acetone, methyl ethyl ketone, etc.) and / or water. The undercoat layer coating solution may contain an infrared absorber.
Various known methods can be used as a method of applying the undercoat layer coating solution to the support. Examples thereof include bar coater coating, spin coating, spray coating, curtain coating, dip coating, air knife coating, blade coating, and roll coating.
The coating amount (solid content) of the undercoat layer is preferably from 0.1-100 mg / ^{m 2,} and more preferably 1 to 30 mg / ^{m 2.}

[Protective layer]
The lithographic printing plate precursor of the present invention is protected on the image recording layer as necessary to impart oxygen barrier properties, prevent scratches in the image recording layer, prevent ablation that occurs during high-illuminance laser exposure, etc. A layer (overcoat layer) can be provided.
Usually, the exposure processing of a lithographic printing plate is carried out in the atmosphere. The image forming reaction in the image recording layer caused by the exposure process can be inhibited by low molecular compounds such as oxygen and basic substances present in the atmosphere. The protective layer prevents low molecular compounds such as oxygen and basic substances from entering the image recording layer, and as a result, suppresses image formation inhibition reaction in the air. Therefore, the property desired for the protective layer is to reduce the permeability of low-molecular compounds such as oxygen, and furthermore, the transparency of light used for exposure is good, and the adhesiveness with the image recording layer is excellent. And it can be easily removed in an on-press development process after exposure. The protective layer having such characteristics is described in, for example, US Pat. No. 3,458,311 and Japanese Patent Publication No. 55-49729.

  As a material used for the protective layer, either a water-soluble polymer or a water-insoluble polymer can be appropriately selected and used. Specifically, for example, polyvinyl alcohol, modified polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl imidazole, polyacrylic acid, polyacrylamide, partially saponified product of polyvinyl acetate, ethylene-vinyl alcohol copolymer, water-soluble cellulose derivative, gelatin, starch Examples thereof include water-soluble polymers such as derivatives and gum arabic, and polymers such as polyvinylidene chloride, poly (meth) acrylonitrile, polysulfone, polyvinyl chloride, polyethylene, polycarbonate, polystyrene, polyamide, and cellophane. These may be used in combination of two or more as required.

  A relatively useful material among the above materials includes water-soluble polymer compounds having excellent crystallinity. Specifically, water-soluble acrylic resins such as polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl imidazole, and polyacrylic acid, gelatin, gum arabic, and the like are suitable. Among these, water can be applied as a solvent, and at the time of printing Polyvinyl alcohol, polyvinyl pyrrolidone, and polyvinyl imidazole are preferable from the viewpoint that they are easily removed by the fountain solution. Among them, polyvinyl alcohol (PVA) gives the best results for basic properties such as oxygen barrier properties and development removability.

  The polyvinyl alcohol that can be used in the protective layer may be partially substituted with an ester, an ether, and an acetal as long as it contains a substantial amount of an unsubstituted vinyl alcohol unit having the required water solubility. Similarly, a part may contain other copolymerization components. For example, various hydrophilic modification sites such as anion modification sites modified with anions such as carboxyl groups and sulfo groups, cation modification sites modified with cations such as amino groups and ammonium groups, silanol modification sites, and thiol modification sites are randomly selected. Polyvinyl alcohol having various degrees of polymerization, the anion-modified site, the cation-modified site, the silanol-modified site, the thiol-modified site, the alkoxyl-modified site, the sulfide-modified site, and the ester modification of vinyl alcohol and various organic acids. Polyvinyl alcohol having various degrees of polymerization having various modified sites such as a site, an ester-modified site of the anion-modified site and alcohols, an epoxy-modified site, etc. at the polymer chain end is also preferably used.

  Suitable examples of the modified polyvinyl alcohol include compounds having a hydrolysis degree of 71 to 100 mol% and a polymerization degree in the range of 300 to 2400. Specifically, PVA-105, PVA-110, PVA-117, PVA-117H, PVA-120, PVA-124, PVA124H, PVA-CS, PVA-CST, PVA-HC, PVA manufactured by Kuraray Co., Ltd. -203, PVA-204, PVA-205, PVA-210, PVA-217, PVA-220, PVA-224, PVA-217EE, PVA-217E, PVA-220E, PVA-224E, PVA-405, PVA-420 , PVA-613, L-8, and the like. Examples of the modified polyvinyl alcohol include KL-318, KL-118, KM-618, KM-118, SK-5102 having an anion-modified site, C-318, C-118 and CM-318 having a cation-modified site. M-205 and M-115 having terminal thiol modification sites, MP-103, MP-203, MP-102 and MP-202 having terminal sulfide modification sites, and ester modification sites with higher fatty acids HL-12E, HL-1203, and other reactive silane-modified R-1130, R-2105, R-2130, and the like.

The protective layer preferably contains a layered compound. The layered compound is a particle having a thin plate-like shape. For example, the following general formula A (B, C) 2-5D ₄ O ₁₀ (OH, F, O) ₂
[However, A is any of Li, K, Na, Ca, Mg, organic cation, B and C are any of Fe (II), Fe (III), Mn, Al, Mg, V, and D is Si or Al. And mica groups such as natural mica and synthetic mica, talc, teniolite, montmorillonite, saponite, hectorite, zirconium phosphate and the like represented by the formula 3MgO.4SiO.H ₂ O.
Examples of natural mica used in the protective layer include muscovite, soda mica, phlogopite, biotite, and sericite. Further, as the synthetic mica, non-swelling mica such as fluorine phlogopite mica ₃ (AlSi ₃ O ₁₀ ) F ₂ , potassium tetrasilicon mica KMg _2.5 Si ₄ O ₁₀ ) F ₂ , and Na tetrasilicic mica NaMg _2.5 (Si ₄ O ₁₀ ) F ₂ , Na or Li teniolite (Na, Li) Mg ₂ Li (Si ₄ O ₁₀ ) F ₂ , montmorillonite-based Na or Li hectorite (Na, Li) 1/8 Mg _{2 / 5Li 1/8 (Si 4} O 10) swelling mica _{F 2.} Synthetic smectite is also useful.

Among the above layered compounds, fluorine-based swellable mica which is a synthetic layered compound is particularly useful from the viewpoint of availability and uniformity. That is, swellable clay minerals such as mica, montmorillonite, saponite, hectorite, bentonite, etc. have a laminated structure composed of unit crystal lattice layers with a thickness of about 10 to 15 mm, and metal atom substitution in the lattice is other than Significantly greater than viscous minerals. As a result, the lattice layer has a shortage of positive charges, and in order to compensate for this, organic cations such as Li ⁺ , Na ⁺ , Ca ²⁺ , Mg ²⁺ , amine salts, quaternary ammonium salts, phosphonium salts and sulfonium salts are provided between the layers. Adsorbs cations. These layered compounds swell with water. If shear is applied in this state, it will easily cleave and form a stable sol in water. Bentonite and swelling synthetic mica have this tendency.

As the shape of the layered compound, from the viewpoint of diffusion control, the thinner the better, the better the planar size as long as the smoothness of the coated surface and the transmittance of actinic rays are not impaired. Accordingly, the aspect ratio is 20 or more, preferably 100 or more, particularly preferably 200 or more. The aspect ratio is the ratio of the thickness to the major axis of the particle, and can be measured, for example, from a projected view of the particle by a micrograph. The larger the aspect ratio, the greater the effect that can be obtained.
The average particle diameter of the layered compound is 1 to 20 μm, preferably 1 to 10 μm, particularly preferably 2 to 5 μm. When the particle diameter is smaller than 1 μm, the suppression of permeation of oxygen and moisture is insufficient and the effect cannot be exhibited sufficiently. On the other hand, if it is larger than 20 μm, the dispersion stability in the coating solution is insufficient, resulting in a problem that stable coating cannot be performed. The average thickness of the particles is 0.1 μm or less, preferably 0.05 μm or less, particularly preferably 0.01 μm or less. For example, among inorganic layered compounds, the size of the swellable synthetic mica that is a representative compound is about 1 to 50 nm in thickness and about 1 to 20 μm in surface size.

When the inorganic layered compound particles having such a large aspect ratio are contained in the protective layer, the coating film strength is improved, and the permeation of oxygen and moisture can be effectively prevented. Deterioration is prevented, and even when stored for a long time under high-humidity conditions, the storage stability of the planographic printing plate precursor does not deteriorate due to changes in humidity, and the storage stability is excellent.
It is preferable that content of the inorganic stratiform compound in a protective layer is 5/1-1/100 by mass ratio with respect to the quantity of the binder used for a protective layer. Even when a plurality of inorganic layered compounds are used in combination, the total amount of these inorganic layered compounds is preferably the above-described mass ratio.

  When the inorganic layered compound is used for the protective layer, it is preferable to add a phosphonium compound to the image recording layer and / or the protective layer in order to improve the inking property. The phosphonium compound is preferably a phosphonium compound represented by the following general formula (v) or (vi). Especially, the phosphonium compound represented by general formula (v) is preferable.

In formula (v), Ar _{1 to} Ar ₆ each independently represents an aryl group or a heterocyclic group, L represents a divalent linking group, X ⁿ⁻ represents an n-valent counter anion, and n represents Represents an integer of 1 to 3, and m represents a number satisfying nxm = 2. Here, as the aryl group, phenyl group, naphthyl group, tolyl group, xylyl group, fluorophenyl group, chlorophenyl group, bromophenyl group, methoxyphenyl group, ethoxyphenyl group, dimethoxyphenyl group, methoxycarbonylphenyl group, dimethylaminophenyl A group and the like are preferable. Examples of the heterocyclic group include a pyridyl group, a quinolyl group, a pyrimidinyl group, a thienyl group, and a furyl group.

  L represents a divalent linking group. 6-15 are preferable and, as for carbon number in a coupling group, More preferably, it is a C6-C12 coupling group.

X ⁻ represents a counter anion, and preferred examples include halogen anions such as Cl ⁻ , Br ⁻ and I ⁻ , sulfonate anions, carboxylate anions, sulfate anions, PF 6 ⁻ , BF 4 ⁻ and perchlorate anions. Can be mentioned. Of these, halogen anions such as Cl ⁻ , Br ⁻ and I ⁻ , sulfonate anions, and carboxylate anions are particularly preferable.

  Specific examples of the phosphonium salt represented by the general formula (v) used in the present invention are shown below.

In the general formula (vi), R _{1 to} R ₄ are each independently an alkyl group, alkenyl group, alkynyl group, cycloalkyl group, alkoxy group, aryl group, aryloxy group, which may have a substituent, An alkylthio group, a heterocyclic group or a hydrogen atom is represented. At least two of R _{1 to} R ₄ may be bonded to form a ring. X ⁻ represents a counter anion.
Here, when R _{1 to} R ₄ are an alkyl group, an alkoxy group or an alkylthio group, the carbon number is usually 1 to 20, and when R _{1 to} R ₄ is an alkenyl group or an alkynyl group, the carbon number is usually 2 to 15 and a cycloalkyl group. In some cases, the number of carbon atoms is usually 3 to 8, the aryl group is a phenyl group, a naphthyl group, etc., the aryloxy group is a phenoxy group, a naphthyloxy group, etc., the arylthio group is a phenylthio group, etc. Examples of the group include a furyl group and a thienyl group. Examples of the substituent that may be present include, for example, alkyl groups, alkenyl groups, alkynyl groups, cycloalkyl groups, alkoxy groups, alkoxycarbonyl groups, acyl groups, alkylthio groups, aryl groups, aryloxy groups, arylthio groups. Group, sulfino group, sulfo group, phosphino group, phosphoryl group, amino group, nitro group, cyano group, hydroxyl group, halogen atom and the like. These substituents may further have a substituent.
Examples of the anion represented by X ⁻ include halide ions such as Cl ⁻ , Br ⁻ and I ⁻ , inorganic acid anions such as ClO ₄ ⁻ , PF ₆ ⁻ and SO ₄ ⁻² , organic carboxylate anions and organic sulfonate anions. Can be mentioned. Examples of the organic group of the organic carboxylate anion and organic sulfonate anion include methyl, ethyl, propyl, butyl, phenyl, methoxyphenyl, naphthyl, fluorophenyl, difluorophenyl, pentafluorophenyl, thienyl, pyrrolyl and the like. Among these, Cl ⁻ , Br ⁻ , I ⁻ , ClO ₄ ⁻ , PF ₆ ^{− and the} like are preferable. Specific examples of phosphonium compounds suitable for the present invention are shown below.

  The addition amount of the phosphonium salt to the image recording layer or the protective layer is preferably 0.01 to 20% by mass, more preferably 0.05 to 10% by mass in the solid content of each layer, and 0.1 to 5% by mass. Most preferred. Within these ranges, good ink fillability can be obtained.

  As another composition of the protective layer, glycerin, dipropylene glycol and the like can be added in an amount corresponding to several mass% with respect to the (co) polymer to provide flexibility. Anionic surfactants such as sodium acid salts; amphoteric surfactants such as alkylaminocarboxylates and alkylaminodicarboxylates; nonionic surfactants such as polyoxyethylene alkylphenyl ethers can be added. The addition amount of these activators can be added in an amount of 0.1 to 100% by mass with respect to the (co) polymer.

  In order to improve the adhesion to the image area, for example, JP-A-49-70702 and British Patent Application No. 1303578 disclose an acrylic polymer in a hydrophilic polymer mainly composed of polyvinyl alcohol. It is described that sufficient adhesion can be obtained by mixing 20 to 60% by mass of a water-based emulsion, a water-insoluble vinylpyrrolidone-vinyl acetate copolymer and the like, and laminating the mixture on an image recording layer. Any of these known techniques can be used in the present invention.

  Furthermore, other functions can be imparted to the protective layer. For example, by adding a colorant (for example, a water-soluble dye) that is excellent in the transparency of infrared rays used for exposure and that can efficiently absorb light of other wavelengths, safe light is not caused. Suitability can be improved.

  Next, an example of a general dispersion method of the layered compound used for the protective layer will be described. First, 5 to 10 parts by mass of the swellable laminar compound mentioned above as a preferred laminar compound is added to 100 parts by mass of water, and the mixture is thoroughly swelled and swollen. Examples of the disperser used here include various mills that disperse mechanically by applying a direct force, a high-speed stirring disperser having a large shearing force, and a disperser that provides high-intensity ultrasonic energy. Specifically, ball mill, sand grinder mill, visco mill, colloid mill, homogenizer, tisol bar, polytron, homomixer, homo blender, ketdy mill, jet agitator, capillary emulsifier, liquid siren, electrostrictive ultrasonic generator, An emulsifying device having a Paulman whistle can be used. A dispersion of 5 to 10% by mass of the inorganic stratiform compound dispersed by the above method is highly viscous or gelled and has very good storage stability. When preparing a protective layer coating solution using this dispersion, it is preferably prepared by diluting with water and stirring sufficiently, and then blending with a binder solution.

  This protective layer coating solution includes known anionic surfactants, nonionic surfactants, cationic surfactants, fluorosurfactants and water-soluble plasticizers for improving the physical properties of the coating. Additives can be added. Examples of the water-soluble plasticizer include propionamide, cyclohexanediol, glycerin, sorbitol and the like. A water-soluble (meth) acrylic polymer can also be added. Furthermore, a known additive for improving the adhesion with the image recording layer and the temporal stability of the coating solution may be added to the coating solution.

The protective layer coating solution thus prepared is applied onto the image recording layer provided on the support and dried to form the protective layer. The coating solvent can be appropriately selected in relation to the binder, but when a water-soluble polymer is used, it is preferable to use distilled water or purified water. The method for applying the protective layer is not particularly limited, and a known method such as the method described in US Pat. No. 3,458,311 or Japanese Patent Publication No. 55-49729 can be applied. . Specific examples of the protective layer include blade coating, air knife coating, gravure coating, roll coating coating, spray coating, dip coating, and bar coating.
The coating amount of the protective layer, the coating amount after drying is preferably in the range of 0.01 to 10 g / ^{m 2,} more preferably in the range of 0.02 to 3 g / ^{m 2,} and most preferably 0. in the range of 02~1g / ^{m 2.}

[Lithographic printing method]
As the light source for exposing the lithographic printing plate precursor according to the invention, a known light source can be used. Specifically, various lasers are preferably used as the light source. In the planographic printing method of the present invention, the planographic printing plate precursor is imagewise exposed with an infrared laser. The infrared laser used is not particularly limited, and a solid laser and a semiconductor laser that emit infrared rays having a wavelength of 760 to 1200 nm are preferable.
The exposure mechanism may be any of an internal drum system, an external drum system, a flat bed system, and the like. The output of the infrared laser is preferably 100 mW or more. In order to shorten the exposure time, it is preferable to use a multi-beam laser device. The exposure time per pixel is preferably within 20 μs. Moreover, it is preferable that irradiation energy amount is 10-300 mJ / cm < ² >.

In the lithographic printing method of the present invention, as described above, after exposing the lithographic printing plate precursor of the present invention imagewise with an infrared laser, an oil-based ink and an aqueous component are supplied without any development processing steps. Print.
Specifically, after exposing the lithographic printing plate precursor with an infrared laser, it is mounted on a printing machine without passing through a development process, and after printing the lithographic printing plate precursor on the printing machine, Examples include a method of printing with an infrared laser and printing without going through a development process.

After the lithographic printing plate precursor is imagewise exposed with a laser, printing is performed by supplying an aqueous component and an oil-based ink without passing through a development processing step such as a wet development processing step. The image recording layer cured by the above process forms an oil-based ink receiving portion having an oleophilic surface. On the other hand, in the unexposed portion, the uncured image recording layer is dissolved or dispersed and removed by the supplied aqueous component and / or oil-based ink, and a hydrophilic surface is exposed in the portion.
As a result, the aqueous component adheres to the exposed hydrophilic surface, and the oil-based ink is deposited on the image recording layer in the exposed area, and printing is started. Here, the water-based component or oil-based ink may be first supplied to the plate surface, but the oil-based ink is first used in order to prevent the water-based component from being contaminated by the image recording layer in the unexposed area. It is preferable to supply. As the aqueous component and the oil-based ink, a dampening water for normal lithographic printing and a printing ink are used.
In this way, the lithographic printing plate precursor is subjected to on-press development on an offset printing machine and used as it is for printing a large number of sheets.

  Hereinafter, the present invention will be described in detail with reference to examples of preparation and evaluation of lithographic printing plate precursors to which the polymerizable composition of the present invention is applied, but the present invention is not limited thereto.

(Production of support)
In order to remove rolling oil on the surface of an aluminum plate (material 1050) having a thickness of 0.3 mm, a degreasing treatment was performed at 50 ° C. for 30 seconds using a 10 mass% sodium aluminate aqueous solution, and then the hair diameter was 0.3 mm. The aluminum surface was grained using three bundle-planted nylon brushes and a pumice-water suspension (specific gravity 1.1 g / cm ³ ) having a median diameter of 25 μm and washed thoroughly with water. This plate was etched by being immersed in a 25 mass% sodium hydroxide aqueous solution at 45 ° C for 9 seconds, washed with water, further immersed in 20 mass% nitric acid at 60 ° C for 20 seconds, and washed with water. The etching amount of the grained surface at this time was about 3 g / m ² .
Next, an electrochemical roughening treatment was performed continuously using an alternating voltage of 60 Hz. The electrolytic solution at this time was a 1% by mass aqueous solution of nitric acid (containing 0.5% by mass of aluminum ions), and the liquid temperature was 50 ° C. The AC power source waveform is electrochemical roughening treatment using a trapezoidal rectangular wave alternating current with a time ratio TP of 0.8 msec until the current value reaches a peak from zero, a duty ratio of 1: 1, and a trapezoidal rectangular wave alternating current. Went. Ferrite was used for the auxiliary anode. The current density was 30 A / dm ² at the peak current value, and 5% of the current flowing from the power source was shunted to the auxiliary anode. The amount of electricity in nitric acid electrolysis was 175 C / dm ² when the aluminum plate was the anode. Then, water washing by spraying was performed.

Further, in a 0.5% by mass aqueous solution of hydrochloric acid (containing 0.5% by mass of aluminum ions) and an electrolytic solution having a liquid temperature of 50 ° C., nitric acid electrolysis is performed under the condition of an electric quantity of 50 C / dm ² when the aluminum plate is an anode. An electrochemical surface roughening treatment was performed in the same manner, followed by washing with water by spraying. The plate was provided with a direct current anodized film of 2.5 g / m ² at a current density of 15 A / dm ² using 15% by mass sulfuric acid (containing 0.5% by mass of aluminum ions) as an electrolytic solution, then washed with water and dried. The centerline average roughness (Ra) of this substrate was measured using a needle having a diameter of 2 μm and found to be 0.51 μm. Furthermore, the following undercoat liquid (1) was applied so that the dry coating amount was 6 mg / m ² to obtain a support.

-Undercoat liquid (1)-
Undercoat compound (1) (mass average molecular weight: 60,000) 0.017 g
・ Methanol 9.00 g
・ Water 1.00g

[Examples 1 to 9, Comparative Example 1]
1. Preparation of lithographic printing plate precursor An image recording layer coating solution having the following composition was bar-coated on the support having the undercoat layer formed thereon, followed by oven drying at 100 ° C. for 60 seconds, and a dry coating amount of 1.0 g / m ² . An image recording layer was formed.
Subsequently, a protective layer coating solution having the following composition is bar-coated on the image recording layer and oven-dried at 120 ° C. for 60 seconds to form a protective layer having a dry coating amount of 0.15 g / m ^2. Original plates (1) to (9) and a comparative planographic printing plate precursor (R1) were obtained.
The image recording layer coating solution was obtained by mixing and stirring the following photosensitive solutions {(1) to (9), (R1)} and the microgel solution (1) immediately before coating.
In the photosensitive solution (R1) used in Comparative Example 1, instead of the azinium compound according to the present invention represented by (A) the general formula (1), a comparative polymerization initiator (R-1) having the following structure: Was used.

-Photosensitive solutions (1) to (9), (R1)-
(D) Binder polymer (1) 0.177 g
(A) Compound represented by general formula (1) or comparative polymerization initiator (1)
(Compound described in Table 1) Xg
(B) Infrared absorber (1) 0.031 g
(C) Polymerizable monomer (Aronix M-215 (manufactured by Toa Gosei Co., Ltd.)) 0.319 g
Phosphonium compound (1) 0.035 g
Fluorosurfactant (1) 0.004g
Anionic surfactant 0.125g
(Pionine A-24-EA (Takemoto Yushi Co., Ltd., 40% by mass aqueous solution)
Methyl ethyl ketone 2.554g
1-methoxy-2-propanol 7.023 g

-Microgel solution (1)-
Microgel dispersion (1) 1.800 g
1.678 g of water

-Synthesis of microgel dispersion (1)-
As an oil phase component, trimethylolpropane and xylene diisocyanate adduct (manufactured by Mitsui Takeda Chemical Co., Ltd., Takenate D-110N, 75% by mass ethyl acetate solution) 10.0 g, as a polymerizable monomer Aronix M-215 (Toa Synthesis Co., Ltd.) 6.00 g and Piionin A-41C (Takemoto Yushi Co., Ltd.) 0.12 g were dissolved in ethyl acetate 16.67 g. As an aqueous phase component, 37.5 g of a 4 mass% aqueous solution of PVA-205 was prepared. The oil phase component and the aqueous phase component were mixed and emulsified for 10 minutes at 12,000 rpm using a homogenizer. The obtained emulsion was added to 25 g of distilled water, stirred at room temperature for 30 minutes, and then stirred at 40 ° C. for 2 hours. The microcapsule liquid thus obtained was diluted with distilled water to a solid content concentration of 21% by mass to obtain a microgel dispersion (1). The average particle size was 0.23 μm.
The structure of each compound used in the photosensitive solution is shown below.

1.5 g of protective layer coating solution / layered compound dispersion (1) below
・ Polyvinyl alcohol 0.06g
(PVA105, manufactured by Kuraray Co., Ltd., saponification degree 98.5 mol%, polymerization degree 500)
・ Polyvinylpyrrolidone 0.01g
(Polyvinylpyrrolidone K30, manufactured by Tokyo Chemical Industry Co., Ltd., molecular weight Mw = 40,000)
・ Vinyl pyrrolidone / vinyl acetate copolymer 0.01g
(LUVITEC VA64W, manufactured by ISP, copolymerization ratio = 6/4)
-Nonionic surfactant 0.01g (Emalex 710, manufactured by Nippon Emulsion Co., Ltd.)
・ Ion-exchanged water 6.0g

Preparation of Layered Compound Dispersion (1) 6.4 g of synthetic mica Somasif ME-100 (manufactured by Co-op Chemical) is added to 193.6 g of ion-exchanged water, and the average particle size (laser scattering method) is adjusted to 3 μm using a homogenizer. Dispersed until The aspect ratio of the obtained layered compound particles was 100 or more.

2. Evaluation (exposure) of lithographic printing plate precursor
The obtained lithographic printing plate precursors (1) to (9) and (R1) were output on a Trend setter 3244VX manufactured by Creo equipped with a water-cooled 40 W infrared semiconductor laser under the conditions of an output of 11.7 W, an outer drum rotational speed of 250 rpm, and a resolution of 2400 dpi. Exposed.

(Evaluation of plate inspection)
The obtained exposed original plate was left as it was for 30 minutes in a dark place, at 25 ° C. and in an atmosphere of 50% relative humidity, and then the plate inspection property was evaluated. The ease of plate inspection was expressed as the difference ΔL between the L value of the exposed area and the L value of the unexposed area using the L value (brightness) of the L ^* a ^* b ^* color system. It means that the larger the value of ΔL is, the better the plate inspection property is. If this value is 2.0 or more, it can be said that the plate inspection property is visually excellent. The measurement was performed by the SCE (regular reflection light removal) method using a spectrocolorimeter CM2600d manufactured by KONICA-MINOLTA and operation software CM-S100W. In the SCE method, specularly reflected light is removed and only diffused light is measured. Therefore, the color is evaluated visually, and correlates well with an actual human inspection. The results are shown in Table 1.

(Evaluation of on-press developability)
Further, the obtained exposed original plate is not developed and attached to a cylinder of a printing machine SOR-M manufactured by Heidelberg, and dampening water (EU-3 (Etchi solution manufactured by FUJIFILM Corporation) / water / isopropyl. Alcohol = 1/89/10 (volume ratio)) and TRANS-G (N) black ink (manufactured by Dainippon Ink & Chemicals, Inc.), and after supplying dampening water and ink, 6,000 hours per hour Printing was performed at the printing speed of the sheet. All of the lithographic printing plate precursors were developed on-press with 20 or less printing papers, indicating excellent on-press developability.

(Evaluation of printing durability)
When printing is continued and the number of printed sheets is increased, the image recording layer gradually wears and the ink acceptability is lowered, so that the ink density in the printing paper is lowered. Printing durability was evaluated by the number of printed sheets when the ink density (reflection density) was reduced by 0.1 from the start of printing. The results are shown in Table 1. The larger the number of sheets, the better the printing durability.

  From the results in Table 1, it was confirmed that the lithographic printing plate precursor to which the polymerizable composition of the present invention was applied had good plate inspection after laser exposure and excellent visibility. Moreover, all the lithographic printing plate precursors exhibited excellent on-press developability and practically sufficient printing durability as a printing plate.

Claims (13)

(A) a compound represented by the following general formula (1), (B) an infrared absorber, and (C) a compound having at least one ethylenically unsaturated bond capable of addition polymerization. Polymerizable composition.

(In the formula, R ¹ represents a monovalent organic group, and R ² to R ⁶ each independently represents a hydrogen atom, a halogen atom, or a monovalent organic group. X ⁻ represents an arbitrary anion. At least one of A, B, and D represents a nitrogen atom, and the other represents a carbon atom, and when any of A, B, and D is a nitrogen atom, R ⁵ , R ^4, and R bonded thereto ³ represents an unshared electron pair, and R ¹ and R ² , R ² and R ³ , R ³ and R ⁴ , R ⁴ and R ⁵ , R ⁵ and R ⁶ , and R ⁶ and R in the formula ¹ may be bonded to each other to form an aromatic ring or a heterocyclic ring together with the carbon atoms to which they are bonded, and may form a condensed ring as a whole.   (A) In the said General formula (1), one of A, B, and D is a nitrogen atom, A or D is a nitrogen atom, The polymeric composition of Claim 1 characterized by the above-mentioned.   (A) In the said General formula (1), two of A, B, and D are nitrogen atoms, A and D are nitrogen atoms, The polymeric composition of Claim 1 characterized by the above-mentioned.   (A) In the said General formula (1), only B is a nitrogen atom among A, B, and D, The polymeric composition of Claim 1 characterized by the above-mentioned.   The polymerizable composition according to claim 1, wherein the (B) infrared absorber is a cyanine dye.   6. The polymerizable composition according to claim 5, wherein the (B) infrared absorber is a compound having a solvent-soluble group in the molecule.   The solvent-soluble group of the (B) infrared absorber is at least one selected from the group consisting of an alkyloxy group, an aryloxy group, an alkyloxycarbonyl group, and an aryloxycarbonyl group. Polymerizable composition. The said (B) infrared absorber has the cyanine dye structure represented by following General formula (2), and has at least 1 solvent-soluble group in a molecule | numerator. A polymerizable composition.

(In the formula, Z ¹ and Z ² each independently represent an aromatic ring or a heteroaromatic ring which may have a substituent. R ³ and R ⁴ each independently represents a carbon which may have a substituent. Represents a hydrocarbon group having a number of 20 or less, and R ⁹ and R ¹⁰ each independently represents a hydrogen atom or an alkoxy group which may have a substituent, Za ⁻ is present when neutralization of charge is required. Represents a counter anion.)   The (B) infrared absorber has a salt structure composed of a cation and an anion, and at least one of the anion and the anion of the compound represented by (A) the general formula (1) is an inorganic anion. The polymerizable composition according to any one of claims 1 to 8.   The polymerizable composition according to any one of claims 1 to 9, wherein the polymerizable composition further contains (D) a binder polymer.   The polymerizable composition according to any one of claims 1 to 10, wherein the polymerizable composition contains (E) a microcapsule or a microgel.   A lithographic printing plate precursor comprising the polymerizable composition according to any one of claims 1 to 11 and having an image recording layer removed by an oily ink and / or an aqueous component on a support.   The above-described lithographic printing plate precursor is image-wise exposed with an infrared laser, and printing is performed by supplying an oil-based ink and an aqueous component without performing any development treatment on the exposed lithographic printing plate precursor. A planographic printing method comprising: removing an infrared laser unexposed portion of the image recording layer with an oil-based ink and / or an aqueous component in the course of the printing step.