JP4369375B2 - Positive lithographic printing plate precursor for infrared laser - Google Patents

Description

  The present invention relates to a positive lithographic printing plate precursor for infrared lasers, and more particularly to a so-called lithographic printing plate precursor capable of direct plate making that can be directly made by scanning an infrared laser based on a digital signal from a computer or the like.

  In recent years, the development of lasers has been remarkable, and in particular, solid-state lasers and semiconductor lasers having a light emitting region from the near infrared to the infrared can easily obtain high-power and small-sized ones. These lasers are very useful as an exposure light source when directly making a plate from digital data such as a computer.

The recording layer in such an infrared laser compatible positive lithographic printing plate precursor comprises a binder resin that is soluble in an alkaline aqueous solution, a dissolution inhibitor that substantially reduces the solubility of the binder resin by interaction with the binder resin, and a light. And a photothermal conversion agent such as an infrared absorbing dye that absorbs and generates heat. Among these photothermal conversion agents, in particular, the cyanine dye also has a function as the dissolution inhibitor, and thus is suitably used as a photothermal conversion agent for recording layers compatible with infrared lasers.
However, in such an infrared laser-compatible recording layer, the difference between the solubility resistance of the unexposed area (image area) with respect to the developer and the solubility of the exposed area (non-image area) under various use conditions ( Discrimination (hereinafter referred to as “dissolving discrimination”) is still not sufficient, and there is a problem that overdevelopment and development failure are liable to occur due to variations in use conditions.

In order to solve the above problem, there is a technique for improving dissolution discretion by using a photosensitive composition (for example, refer to Patent Document 1) in which most of an aqueous alkali-soluble binder resin is formed of a novolac resin. Are known. This novolac resin dissolves in the developer in unexposed areas due to hydrogen bonding between phenolic hydroxyl groups or interaction with other additives (for example, dissolution inhibitors) contained in the photosensitive composition. Therefore, the dissolution discrepancy is increased by increasing the solubility in the exposed portion by heat.
In addition, by using an onium salt compound such as a sulfonium salt or iodonium salt having a very high dissolution inhibiting ability as a dissolution inhibitor, the alkali developability of the image area is improved. A method of enlarging (image contrast) is also known (see, for example, Patent Document 2).
Although these methods have achieved certain results with respect to the expansion of dissolution discreet, there is still room for improvement in terms of expansion of dissolution discrepancies, and further improvements in development stability (development latitude) are desired. It is rare.

On the other hand, in the positive recording layer to which the above method is applied, when the surface state is slightly changed by touching the surface of the recording layer during handling, the dissolution inhibiting ability in the unexposed area (image area) is reduced. Therefore, there is a problem that the image portion is dissolved and becomes a scratch mark during development with an alkaline aqueous solution having a high pH, resulting in deterioration of printing durability and poor inking property.
In order to improve the scratch resistance, a method of adding a low molecular weight wax to the recording layer (for example, see Patent Document 3) and a method of providing a protective layer on the recording layer have been proposed. . However, these methods have a problem that the sensitivity of the recording layer is lowered, and the wax and the protective layer are melted during development and cause stains during printing.
European Patent Application No. 823327A2 Japanese Patent No. 2577718 JP 2000-35666 A

An object of the present invention is to solve the conventional technical problems and achieve the following objects.
That is, an object of the present invention is to provide a positive lithographic printing plate precursor for infrared lasers which has a large dissolution discrepancy and excellent development latitude and is also excellent in scratch resistance.

As a result of intensive studies, the present inventors have found that the above object can be achieved by adding a sulfonium salt having an acid group protected by a protective group to the recording layer, and the present invention has been completed. .
Namely, the positive lithographic printing plate precursor for infrared laser of the present invention comprises (A) a water-insoluble and alkali-soluble resin, (B) an infrared absorber, and (C) the following general formula, on a supporting rest having a hydrophilic surface. It has a recording layer containing the sulfonium salt represented by (1) and having increased solubility in an alkaline aqueous solution upon exposure with an infrared laser.

[In the general formula (1), R ₁ and R ₂ each independently be TABLE an alkyl group, a cycloalkyl group, an aralkyl group, or an aryl group. Ar is an —O—R group that is converted to a hydroxyl group by decomposing by the action of an acid or heat (wherein R represents a protecting group, and —CO ₂ — is not included as a linking group forming the protecting group) . ), and an aromatic having at least one substituent -COO-R 'groups (where R' to convert it to decompose by the action of an acid or heat to the carboxyl group is selected from representative.) the protecting group Represents a group hydrocarbon group. X ^- is to display the residue derived from a compound having a pKa of less than 5. R ₁ and R ₂ may be bonded to each other to form a cyclic structure. ]

  The recording layer in the present invention may be a single layer or may have a multilayer structure composed of a plurality of layers having different constituent components. In the case of a recording layer having a multilayer structure, an embodiment in which the above-mentioned sulfonium salt is added to the uppermost layer is preferable from the viewpoint of the addition effect.

Although the operation of the present invention is not clear, it is presumed as follows.
The sulfonium salt contained in the recording layer in the present invention has, within its structure, an —O—R group (wherein R represents a protective group, which is converted to a hydroxyl group by being decomposed by the action of an acid or heat). -CO ₂ -is not included as a linking group to form a group ) and / or a -COO-R 'group (wherein R' is a protective group) which is converted into a carboxyl group by decomposition by the action of an acid or heat. the expressed.) (hereinafter, having called protecting acid group.). That is, this group means a state in which the acid group is capped (protected) by a degradable protecting group. In the recording layer containing a sulfonium salt having such a protective acid group, the unexposed portion (image portion) has improved film strength due to the excellent ability of the onium salt compound to inhibit dissolution, and the acid group is protected. It seems that it is excellent in alkali solubility resistance. For this reason, the lithographic printing plate precursor of the present invention is effective in suppressing the dissolution by the alkaline developer even in the fluctuation region even if the surface state of the recording layer fluctuates during handling or the like. It is presumed that scratch marks that cause the damage are difficult to form.
On the other hand, in the exposed area (non-image area), the protecting group is decomposed by a heat energy generated by exposure and / or an acid generated by the decomposition of the sulfonium salt to be converted into a hydroxyl group or a carboxyl group. Therefore, it is considered that high developability for an alkali developer can be secured. Thus, in the lithographic printing plate precursor according to the present invention, it is presumed that the excellent film strength of the unexposed area and the excellent developability of the exposed area are compatible, and as a result, the dissolution disc is expanded.

  According to the present invention, it is possible to provide an infrared laser-compatible positive planographic printing plate precursor having a large dissolution discrepancy and excellent development latitude and excellent scratch resistance.

The infrared laser positive positive lithographic printing plate precursor (hereinafter sometimes simply referred to as “lithographic printing plate precursor”) of the present invention will be described in detail below.
The planographic printing plate precursor of the present invention is represented by (A) a water-insoluble and alkali-soluble resin, (B) an infrared absorber, and (C) the following general formula (1) on a support having a hydrophilic surface. It has a recording layer containing a sulfonium salt (hereinafter referred to as a specific sulfonium salt as appropriate) and having increased solubility in an alkaline aqueous solution upon exposure with an infrared laser.
The recording layer in the present invention is not particularly limited in its layer structure, and may be a single layer structure or a multilayer structure composed of a plurality of layers having different constituent components. In the case where the recording layer has a multilayer structure, the specific polymer compound may be contained in any layer, but in particular, an embodiment in which a specific sulfonium salt is added to the uppermost layer is preferable from the viewpoint of the effect of addition. .
First, each component constituting the recording layer in the lithographic printing plate precursor according to the invention will be described.

[(C) Specific sulfonium salt]
The specific sulfonium salt constituting the recording layer in the invention has a structure represented by the following general formula (1).

In the general formula (1), R ¹ and R ² each independently represent an alkyl group, a cycloalkyl group, an aralkyl group, or an aryl group, and in particular, both R ¹ and R ² are aryl groups. It is preferable that
The alkyl group represented by R ¹ and R ² is preferably an alkyl group having 1 to 30 carbon atoms, such as a methyl group, an ethyl group, a propyl group, an n-butyl group, a sec-butyl group, t Examples include linear or branched alkyl groups such as -butyl group, among which n-butyl group, sec-butyl group and t-butyl group are preferable. These alkyl groups may further have a substituent.

Examples of the cycloalkyl group represented by R ¹ and R ² include a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, an adamantyl group, a norbornyl group, and a boronyl group. Among them, a cyclopentyl group and a cyclohexyl group are preferable. . These cycloalkyl groups may further have a substituent.

The aralkyl group represented by R ¹ and R ² is preferably an aralkyl group having 7 to 12 carbon atoms, and examples thereof include a benzyl group, a phenethyl group, and a cumyl group, and among them, a phenethyl group is preferable. These aralkyl groups may further have a substituent.

The aryl group represented by R ¹ and R ² is preferably an aryl group having 6 to 18 carbon atoms, and examples thereof include a phenyl group, a naphthyl group, and an anthracenyl group, and among them, a phenyl group and a naphthyl group. Are preferable, and a phenyl group is more preferable. These aryl groups may further have a substituent.

R ¹ and R ² may be bonded to each other to form a cyclic structure together with S ⁺ . In this case, the group formed by combining R ¹ and R ² is, for example, an alkylene group having 4 to 10 carbon atoms, preferably a butylene group, a pentylene group or a hexylene group, particularly preferably a butylene group or pentylene. The group can be mentioned.
Further, a hetero atom may be contained in the cyclic structure formed by combining R ¹ and R ² together with S ⁺ .

In the general formula (1), Ar represents an —O—R group which is converted to a hydroxyl group by being decomposed by the action of an acid or heat (where R represents a protective group, and the linking group forms the protective group). as -CO 2 _-. containing no), and, -COO-R 'groups (where R' to convert it to decompose by the action of an acid or heat to the carboxyl group is selected from the representative) protecting group. It represents an aromatic hydrocarbon group having at least one substituent.
First, an —O—R group that is converted to a hydroxyl group by being decomposed by the action of an acid or heat (wherein R represents a protecting group, and —CO ₂ — is not included as a linking group forming the protecting group ). And —COO—R ′ group (wherein R ′ represents a protecting group) which is converted into a carboxyl group by being decomposed by the action of an acid or heat . This group has a structure in which an acid group of a hydroquinle group and / or a carboxyl group is capped (protected) by a degradable protecting group, and the acid group appears by decomposing the protecting group. Hereinafter, such a group will be described as a protective acid group.

  The protective acid group in the present invention has a structure of —O—R or —COO—R ′. Here, R and R 'are protecting groups. As the protecting group, a hydroxyl protecting group and a carboxyl protecting group commonly used in the field of organic synthesis can be used. Specifically, “Protective Groups In Organic Synthesis (Second Edition)”, Theodora W., et al. Greene, Peter G. M.M. Wuts, John Wiley & Sons Inc. The protecting groups described in publishing, 1991, p143-p276 are used.

More specifically, the protecting groups R and R ′ are composed of the following terminal groups or a combination of the following linking groups and terminal groups. In addition, when protecting group R and R 'are comprised combining a coupling group and a terminal group, the combination is arbitrary and you may combine multiple coupling groups and terminal groups.
As the linking group constituting the protective group, a linear, branched or cyclic alkylene group, alkenylene group, arylene group, heteroarylene group, or aralkylene group, —O—, —S—, —C (═O) —, ^{-N (R 4) -, -} SO -, - SO 2 -, - CO 2 -, - N (R 4) SO 2 -, - P <, - P (= O) <, - P (= S) <Is mentioned. R ⁴ represents a hydrogen atom or an alkyl group (specific examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, and a t-butyl group. And an alkyl group having 1 to 4 carbon atoms such as a group.).
Examples of the terminal group constituting the protective group include a linear, branched or cyclic alkyl group, alkenyl group, aryl group, heterocyclic group, condensed ring group, aralkyl group, amino group, or trialkylsilyl group. .
These linking groups and terminal groups may further have a substituent depending on the structure. Examples of the substituent that can be introduced include a halogen atom, an alkyl group, an aryl group, an alkoxy group, a formyl group, and an amino group. , A nitro group, an alkyl halide group, and the like.

Examples of the linear, branched or cyclic alkylene group include those having 1 to 10 carbon atoms such as a methylene group, an ethylene group, a propylene group, a 1,4-butylene group and a 1,4-cyclohexylene group. Can do.
Examples of the arylene group include a phenylene group, a naphthylene group, and an anthrylene group.
Examples of the aralkylene group include a toluylene group, a xylylene group, and a phenethylene group.
As said heteroarylene group, what became a bivalent group in the structure shown by following formula (A1)-(A4) is mentioned.

In the above formulas (A1) to (A3), X represents an oxygen atom, a sulfur atom, or —NH—, and Y ^{1 to} Y ⁶ each independently represent —CH═ or —N═, In A3), at least one of Y ^{1 to} Y ⁶ represents —N═.
In the formula (A4), Y ^{7 to} Y ¹⁴ each independently represent —CH═ or —N═, and at least one of Y ^{7 to} Y ¹⁴ represents —N═.

These protecting groups are decomposed by the action of acid or heat. About the aspect of decomposition | disassembly of a protecting group, it shows below.
In general, a resist of a chemical amplification system in which a compound that generates an acid upon irradiation with light (PAG: Photo Acid Generator) and a compound protected with an acid-decomposable group has a high resistance because the decomposition reaction by acid is thermally amplified. Sensitivity can be expected. In the specific sulfonium salt in the present invention, a compound that generates an acid upon irradiation with light is an anion portion, and a compound protected with an acid-decomposable group corresponds to a cation portion. From this, when the recording layer containing this specific sulfonium salt is exposed by an infrared laser, an acid is generated from the anion portion due to the thermal energy by exposure, and the acid-decomposing group (protecting group) is decomposed by the acid, Deprotected to express carboxyl group and hydroxyl group. That is, in the present invention, the decomposition mechanism of the protecting group is hydrolysis with an acid. In addition, since the decomposition of the protecting group by heat is proportional to the ease of decomposition by an acid, the decomposition mechanism is considered to be the same as the decomposition mechanism by an acid.

In addition, the aromatic hydrocarbon group having the above protecting acid group as a substituent is preferably an aryl group having 6 to 18 carbon atoms, and examples thereof include a phenyl group, a naphthyl group, and an anthracenyl group. Group and a naphthyl group are preferable, and a phenyl group is more preferable.
Further, at least one protective acid group may be substituted on the aromatic ring of the aromatic hydrocarbon group, and a plurality of protective acid groups may be substituted on one aromatic ring. .

X ⁻ in the general formula (1) represents a residue derived from a compound having a pKa of less than 5 . Examples of the residue derived from a compound having a pKa of less than 5 include a residue derived from a compound having a pKa selected from a sulfonic acid compound, a carboxylic acid compound, and an inorganic acid compound of less than 5 .
In residues from pKa which is expressed by less than 5 compound, as the residue of an inorganic acid compound, a halide anion, HS0 ₄ ^{- -} the X, and halogen-containing complex anions, e.g., tetrafluoroborate, Hexafluorophosphate, hexafluoroarsenate, and hexafluoroantimonate. Among these, preferably, a residue you from organic acid compound containing a fluorine atom. Specific examples of the inorganic acid compound containing a fluorine atom include, for example, tetrafluoroboric acid, tetrafluoroaluminic acid, tetrafluoroiron acid, tetrafluorogallic acid, hexafluorophosphoric acid, hexafluoroarsenic acid, hexafluoroantimonic acid, Hexafluorosilicic acid, hexafluoronickic acid, hexafluorotitanic acid, hexafluorozirconic acid and the like can be mentioned, and among them, hexane fluorophosphoric acid, tetrafluoroboric acid, hexafluoroantimonic acid and the like are preferable.

Specific examples of the sulfonic acid compound from which the pKa derived from the residue represented by X ⁻ is less than 5 include, for example, methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid, butanesulfonic acid, pentanesulfonic acid, Hexanesulfonic acid, heptanesulfonic acid, octanesulfonic acid, nonanesulfonic acid, decanesulfonic acid, undecanesulfonic acid, dodecanesulfonic acid, tridecanesulfonic acid, tetradecanesulfonic acid, pentadecanesulfonic acid, hexadecanesulfonic acid, heptadecanesulfonic acid, Alkyl sulfonic acids such as octadecane sulfonic acid, nonadecane sulfonic acid, icosane sulfonic acid, henicosane sulfonic acid, docosane sulfonic acid, tricosane sulfonic acid, tetraconsan sulfonic acid;
For example, fluoromethanesulfonic acid, difluoromethanesulfonic acid, trifluoromethanesulfonic acid, chloromethanesulfonic acid, dichloromethanesulfonic acid, trichloromethanesulfonic acid, bromomethanesulfonic acid, dibromomethanesulfonic acid, tribromomethanesulfonic acid, iodomethanesulfone Acid, diiodomethanesulfonic acid, triiodomethanesulfonic acid, fluoroethanesulfonic acid, difluoroethanesulfonic acid, trifluoroethanesulfonic acid, pentafluoroethanesulfonic acid, chloroethanesulfonic acid, dichloroethanesulfonic acid, trichloroethanesulfonic acid, pentachloroethanesulfone Acid, tribromoethanesulfonic acid, pentabromoethanesulfonic acid, triiodoethanesulfonic acid, pentaiodoethanesulfonic acid, Fluoropropanesulfonic acid, trifluoropropanesulfonic acid, heptafluoropropanesulfonic acid, chloropropanesulfonic acid, trichloropropanesulfonic acid, heptachloropropanesulfonic acid, bromopropanesulfonic acid, tribromopropanesulfonic acid, heptabromopropanesulfonic acid, tri Iodopropanesulfonic acid, heptaiodopropanesulfonic acid, trifluorobutanesulfonic acid, nonafluorobutanesulfonic acid, trichlorobutanesulfonic acid, nonachlorobutanesulfonic acid, tribromobutanesulfonic acid, nonabromobutanesulfonic acid, triiodobutanesulfone Acid, nonaiodobutanesulfonic acid,

Trifluoropentanesulfonic acid, perfluoropentanesulfonic acid, trichloropentanesulfonic acid, perchloropentanesulfonic acid, tribromopentanesulfonic acid, perbromopentanesulfonic acid, triiodopentanesulfonic acid, periododopentanesulfonic acid, trifluorohexane Sulfonic acid, perfluorohexanesulfonic acid, trichlorohexanesulfonic acid, perchlorohexanesulfonic acid, perbromohexanesulfonic acid, periodohexanesulfonic acid, trifluoroheptanesulfonic acid, perfluoroheptanesulfonic acid, trichloroheptanesulfonic acid, perfluorohexane Chloroheptane sulfonic acid, perbromoheptane sulfonic acid, periodate heptane sulfonic acid, trifluorooctane sulfonic acid, perfluorooctance Phosphonic acid, trichlorooctane sulfonic acid, perchlorooctane sulfonic acid, perbromooctane sulfonic acid, periodooctane sulfonic acid, trifluorononane sulfonic acid, perfluorononane sulfonic acid, trichlorononane sulfonic acid, perchlorononane sulfonic acid, per Bromonotenesulfonic acid, periodononanesulfonic acid, trifluorodecanesulfonic acid, perfluorodecanesulfonic acid, trichlorodecanesulfonic acid, perchlorodecanesulfonic acid, perbromodecanesulfonic acid, periodododecanesulfonic acid, trifluoroundecane Sulfonic acid, perfluoroundecane sulfonic acid, trichloroundecane sulfonic acid, perchloroundecane sulfonic acid, perbromoundecane sulfonic acid, bayiodoundecane sulfone , Trifluorododecanesulfonic acid, perfluorododecanesulfonic acid, trichlorododecanesulfonic acid, perchlorododecanesulfonic acid, perbromododecanesulfonic acid, periodododecanesulfonic acid, trifluorotridecanesulfonic acid, perfluorotridecanesulfonic acid, trichloro Tridecanesulfonic acid, perchlorotridecanesulfonic acid, perbromotridecanesulfonic acid, periodotridecanesulfonic acid,

Trifluorotetradecanesulfonic acid, perfluorotetradecanesulfonic acid, trichlorotetradecanesulfonic acid, perchlorotetradecanesulfonic acid, perbromotetradecanesulfonic acid, periodotetradecanesulfonic acid, trifluoropentadecanesulfonic acid, perfluoropentadecanesulfonic acid, trichloropentadecanesulfonic acid Acid, perchloropentadecanesulfonic acid, perbromopentadecanesulfonic acid, periodopentadecanesulfonic acid, perfluorohexadecanesulfonic acid, perchlorohexadecanesulfonic acid, perbromohexadecanesulfonic acid, periodohexadecanesulfonic acid, perfluoroheptadecanesulfonic acid Perchloroheptadecanesulfonic acid, perbromoheptadecanesulfonic acid, perio Heptadecanesulfonic acid, perfluorooctadecanesulfonic acid, berchlorooctadecanesulfonic acid, perpromooctadecanesulfonic acid, periodooctadecanesulfonic acid, perfluorononadecanesulfonic acid, perchlorononadecanesulfonic acid, perbromononadecanesulfonic acid, Periodononadecanesulfonic acid, perfluoroicosanesulfonic acid, perchloroicosanesulfonic acid, perbromoicosanesulfonic acid, periodoicosanesulfonic acid, perfluoroheneicosansulfonic acid, perchlorohicosansulfonic acid , Perbromohedicosan sulfonic acid, periodohenicosan sulfonic acid, perfluorodocosane sulfonic acid, perchlorodocosane sulfonic acid, perbromodocosane sulfonic acid, baiodo docosanth Phosphonic acid, perfluorotricosansulfonic acid, perchlorotricosansulfonic acid, perbromotricosansulfonic acid, periodotricosanesulfonic acid, perfluorotetraconsansulfonic acid, perchlorotetraconsansulfonic acid, perbromotetracene Haloalkyl sulfonic acids such as consan sulfonic acid and periodotetracon san sulfonic acid;

For example, cycloalkyl sulfonic acids such as cyclopentane sulfonic acid and cyclohexane sulfonic acid;
For example, 2-fluorocyclopentanesulfonic acid, 2-chlorocyclopentanesulfonic acid, 2-bromocyclopentanesulfonic acid, 2-iodocyclopentanesulfonic acid, 3-fluorocyclopentanesulfonic acid, 8-chlorocyclopentanesulfonic acid, 3-bromocyclopentanesulfonic acid, 3-iodocyclopentanesulfonic acid, 3,4-difluorocyclopentanesulfonic acid, 3,4-dichlorocyclopentanesulfonic acid, 3,4-dibromocyclopentanesulfonic acid, 3,4- Diiodocyclopentanesulfonic acid, 4-fluorocyclohexanesulfonic acid, 4-chlorocyclohexanesulfonic acid, 4-bromocyclohexanesulfonic acid, 4-iodocyclohexanesulfonic acid, 2,4-difluorocyclohexanesulfonic acid, 2,4 Dichlorocyclohexanesulfonic acid, 2,4-dibromocyclohexanesulfonic acid, 2,4-diiodocyclohexanesulfonic acid, 2,4,6-trifluorocyclohexanesulfonic acid, 2,4,6-trichlorocyclohexanesulfonic acid, 2,4 Halogenated cycloalkyl such as 1,6-tribromocyclohexanesulfonic acid, 2,4,6-triiodocyclohexanesulfonic acid, tetrafluorocyclohexanesulfonic acid, tetrachlorocyclohexanesulfonic acid, tetrabromocyclohexanesulfonic acid, tetraiodocyclohexanesulfonic acid Sulfonic acid;

For example, aromatic sulfonic acids such as benzenesulfonic acid, nanthalenesulfonic acid, anthracenesulfonic acid, phenanthrenesulfonic acid, pyrenesulfonic acid;
For example, 2-fluorobenzenesulfonic acid, 3-fluorobenzenesulfonic acid, 4-fluorobenzenesulfonic acid, 2-chlorobenzenesulfonic acid, 3-chlorobenzenesulfonic acid, 4-chlorobenzenesulfonic acid, 2-bromobenzenesulfonic acid, 3- Promobenzenesulfonic acid, 4-bromobenzenesulfonic acid, 2-iodobenzenesulfonic acid, 4-iodobenzenesulfonic acid, 2,4-difluorobenzenesulfonic acid, 2,6-difluorobenzenesulfonic acid, 2,4-dichlorobenzene Sulfonic acid, 2,6-dichlorobenzenesulfonic acid, 2,4-dibromobenzenesulfonic acid, 2,6-dibromobenzenesulfonic acid, 2,4-diiodobenzenesulfonic acid, 2,6-diiodobenzenesulfonic acid, 2,4,6-trifluorobenze Sulfonic acid, 3,4,5-trifluorobenzenesulfonic acid, 2,4,6-trichlorobenzenesulfonic acid, 3,4,5-trichlorobenzenesulfonic acid, 2,4,6-tribromobenzenesulfonic acid, 3 , 4,5-tribromobenzenesulfonic acid, 2,4,6-triiodobenzenesulfonic acid, 3,4,5-triiodobenzenesulfonic acid, pentafluorobenzenesulfonic acid, pentachlorobenzenesulfonic acid, pentabromobenzenesulfone Acid, pentaiodobenzenesulfonic acid, fluoronaphthalenesulfonic acid, chloronaphthalenesulfonic acid, bromonaphthalenesulfonic acid, iodonaphthalenesulfonic acid, fluoroanthracenesulfonic acid, chloroanthracenesulfonic acid, bromoanthracenesulfonic acid, iodoanthone sense Halogenated aromatic contact sulfonic acids such as acid;

For example, p-toluenesulfonic acid, 4-isopropylbenzenesulfonic acid, 3,5-bis (trimethyl) benzenesulfonic acid, 3,5-bis (isopropyl) benzenesulfonic acid, 2,4,6-tris (trimethyl) benzene Alkyl aromatic sulfonic acids such as sulfonic acid and 2,4,6-tris (isopropyl) benzenesulfonic acid;
For example, 2-trifluoromethylbenzenesulfonic acid, 2-trichloromethylbenzenesulfonic acid, 2-tribromomethylbenzenesulfonic acid, 2-triiodomethylbenzenesulfonic acid, 3-trifluoromethylbenzenesulfonic acid, 3-trichloromethyl Benzenesulfonic acid, 3-tribromomethylbenzenesulfonic acid, 3-triiodomethylbenzenesulfonic acid, 4-trifluoromethylbenzenesulfonic acid, 4-trichloromethylbenzenesulfonic acid, 4-tribromomethylbenzenesulfonic acid, 4- Triiodomethylbenzenesulfonic acid, 2,6-bis (trifluoromethyl) benzenesulfonic acid, 2,6-bis (trichloromethyl) benzenesulfonic acid, 2,6-bis (tribromomethyl) benzenesulfonic acid, 2, 6-bis ( Lyodomethyl) benzenesulfonic acid, 3,5-bis (trifluoromethyl) benzenesulfonic acid, 3,5-bis (trichloromethyl) benzenesulfonic acid, 3,5-bis (tribromomethyl) benzenesulfonic acid, 3,5 A halogenated alkyl aromatic sulfonic acid such as bis (triiodomethyl) benzenesulfonic acid;
For example, aromatic aliphatic sulfones such as benzyl sulfonic acid, phenethyl sulfonic acid, phenyl propyl sulfonic acid, phenyl butyl sulfonic acid, phenyl pentyl sulfonic acid, phenyl hexyl sulfonic acid, phenyl heptyl sulfonic acid, phenyl octyl sulfonic acid, and phenyl nonyl sulfonic acid acid;

For example, 4-fluorophenylmethylsulfonic acid, 4-chlorophenylmethylsulfonic acid, 4-bromophenylmethylsulfonic acid, 4-iodophenylmethylsulfonic acid, tetrafluorophenylmethylsulfonic acid, titrachlorophenylmethylsulfonic acid, tetrabromophenylmethyl Sulfonic acid, tetraiodophenylmethylsulfonic acid, 4-fluorophenylethylsulfonic acid, 4-chlorophenylethylsulfonic acid, 4-bromophenylethylsulfonic acid, 4-iodophenylethylsulfonic acid. 4-fluorophenylpropylsulfonic acid, 4-chlorophenylpropylsulfonic acid, 4-bromophenylpropylsulfonic acid, 4-iodophenylpropylsulfonic acid, 4-fluorophenylbutylsulfonic acid, 4-chlorophenylbutylsulfonic acid, 4-bromophenyl Halogenated aromatic aliphatic sulfonic acids such as butylsulfonic acid and 4-iodophenylbutylsulfonic acid;
Examples thereof include alicyclic sulfonic acids such as camphorsulfonic acid and adamantanecarboxylic acid.
Among these, trifluoromethanesulfonic acid, p-toluenesulfonic acid, and methanesulfonic acid are particularly preferable from the viewpoints of availability and production suitability.

Specific examples of the carboxylic acid compound from which the pKa derived from the residue represented by X ⁻ is less than 5 include, for example, formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, isovaleric acid, and pival. Acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, lauric acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, heptadecanoic acid, stearic acid, nonadecanoic acid, icosanoic acid, henicosanoic acid, Aliphatic unsaturated carboxylic acids such as docosanoic acid and tricosanoic acid;
For example, fluoroacetic acid, chloroacetic acid, bromoacetic acid, iodoacetic acid, difluoroacetic acid, dichloroacetic acid, dibromoacetic acid, diiodoacetic acid, trifluoroacetic acid, trichloroacetic acid, tribromoacetic acid, triiodoacetic acid, 2-fluoropropionic acid, 2-chloropropion Acid, 2-bromopropionic acid, 2-iodopropionic acid, trifluoropropionic acid, trichloropropionic acid, pentafluoropropionic acid, pentachloropropionic acid, pentabromopropionic acid, pentaiodopropionic acid, 2,2-bis (Trifluoromethyl) propionic acid, 2,2-bis (trichloromethyl) propionic acid, 2,2-bis (tribromomethyl) propionic acid, 2,2-bis (triiodomethyl) propionic acid, trifluorobutyric acid, Trichlorobutyric acid, pentaful Robutyric acid, heptachlorobutyric acid, heptafluorobutyric acid, heptabromobutyric acid, heptaiobutyric acid, heptafluoroisobutyric acid, heptachloroisobutyric acid, heptabromoisobutyric acid, heptaiodoisobutyric acid, trifluorovaleric acid, 5H-perfluorovaleric acid, 5H-perchloro Valeric acid, 5H-perpromovaleric acid, 5H-periodovaleric acid, nonafluorovaleric acid, nonachlorovaleric acid, nonabromovaleric acid, nonaiodovaleric acid, trifluorohexanoic acid, trichlorohexanoic acid, perfluorohexanoic acid, perchlorohexanoic acid, Perbromohexanoic acid, periodiohexanoic acid, 7-chlorododecafluoroheptanoic acid, 7-chlorododecachloroheptanoic acid, 7-chlorododecabromoheptanoic acid, 7-chlorododecaiodoheptanoic acid, trifluoroheptanoic acid, Chloro heptanoic acid, 7H-perfluoroheptanoic acid, 7H-perchlorethylene heptanoic acid, 7H-Per-bromo heptanoic acid, 7H-per-iodo-heptanoic acid,

Trifluorooctanoic acid, trichlorooctanoic acid, pentadecafluorooctanoic acid, pentadecachlorooctanoic acid, pentadecabromooctanoic acid, pentadeoxyiodooctanoic acid, trifluorononanoic acid, trichlorononanoic acid, 9H-hexadecafluorononanoic acid, 9H-hexadecachlorononanoic acid, 9H-hexadecabromononanoic acid, 9H-hexadecaiodononanoic acid, perfluorononanoic acid, perchlorononanoic acid, perbromononanoic acid, periodononanoic acid, trifluorodecanoic acid, trichlorodecanoic acid , Nonadecafluorodecanoic acid, nonadecachlorodecanoic acid, nonadecabromodecanoic acid, nonadecanoiododecanoic acid, trifluoroundecanoic acid, trichloroundecanoic acid, perfluoroundecanoic acid, perchloroundecanoic acid, perbromo Decanoic acid, periodododecanoic acid, trifluorododecanoic acid, trichlorododecanoic acid, perfluorododecanoic acid, perchlorododecanoic acid, perbromododecanoic acid, periodododecanoic acid, trifluorotridecanoic acid, trichlorotridecanoic acid, perfluorotridecanoic acid Decanoic acid, perchlorotridecanoic acid, perbromotridecanoic acid, periodotridecanoic acid, trifluorotetradecanoic acid, trichlorotetradecanoic acid, perfluorotetradecanoic acid, perchlorotetradecanoic acid, perbromotetradecanoic acid, periodotetradecanoic acid, Trifluoropentadecanoic acid, trichloropentadecanoic acid, perfluoropentadecanoic acid, perchloropentadecanoic acid, perbromopentadecanoic acid, periodopentadecanoic acid, perfluorohexadecanoic acid Perchlorohexadecanoic acid, perbromohexadecanoic acid, periodohexadecanoic acid, perfluorohebutadecanoic acid, perchloroheptadecanoic acid, perbromoheptadecanoic acid, periodoheptadecanoic acid, perfluorooctadecanoic acid, perchlorooctadecanoic acid, Perbromooctadecanoic acid, periodooctadecanoic acid, perfluorononadecanoic acid, perchlorononadecanoic acid, perbromononadecanoic acid, periodononadecanoic acid, perfluoroicosanoic acid, perchloroicosanoic acid, perbromoicosano Acid, valiodoicosanoic acid, perfluorohenicosanoic acid, perchlorohenicosanoic acid, perbromohenicosanoic acid, periodohenicosanoic acid, perfluorodocosanoic acid, perchlorodocosanoic acid, perbromo Docosanoic acid, periodate doco Halogenated saturated fatty acid carboxylic acids such as sanic acid, perfluorotricosanoic acid, perchlorotricosanoic acid, perbromotricosanoic acid, and periodotricosanoic acid;

For example, hydroxy aliphatic carboxylic acids such as glycolic acid, lactic acid, glyceric acid, 3-hydroxy-2-methylpropionic acid;
For example, 3-hydroxy-2- (trifluoromethyl) propionic acid, 3-hydroxy-2- (trichloromethyl) propionic acid, 3-hydroxy-2- (tribromomethyl) propionic acid, 3-hydroxy-2- ( Triiodomethyl) propionic acid, 2-hydroxy-2- (trifluoromethyl) butyric acid, 2-hydroxy-2- (trichloromethyl) butyric acid, 2-hydroxy-2- (tribromomethyl) butyric acid, 2-hydroxy-2 -Halogenation such as (triiodomethyl) butyric acid and droquine aliphatic carboxylic acid;
For example, cycloaliphatic carboxylic acids such as cyclohexanecarboxylic acid, camphoric acid, adamantanoic acid;
For example, 4-fluorocyclohexanecarboxylic acid, 4-chlorocyclohexanecarboxylic acid, 4-bromocyclohexanecarboxylic acid, 4-iodocyclohexanecarboxylic acid, pentafluorocyclohexanecarboxylic acid, pentachlorocyclohexanecarboxylic acid, pentabromocyclohexanecarboxylic acid, pentaiodo Halogenation of cyclohexanecarboxylic acid, 4- (trifluoromethyl) cyclohexanecarboxylic acid, 4- (trichloromethyl) cyclohexanecarboxylic acid, 4- (tribromomethyl) cyclohexanecarboxylic acid, 4- (triiodomethyl) cyclohexanecarboxylic acid, etc. Alicyclic carboxylic acids;

For example, aromatic carboxylic acids such as benzoic acid, naphthoic acid, anthracene carboxylic acid, pyrene carboxylic acid, pyrylene carboxylic acid, pentaphen carboxylic acid;
For example, fluorobenzoic acid, chlorobenzoic acid, bromobenzoic acid, iodobenzoic acid, difluorobenzoic acid, dichlorobenzoic acid, dibromobenzoic acid, diiodobenzoic acid, trifluorobenzoic acid, trichlorobenzoic acid, tribromobenzoic acid, triiodobenzoic acid , Tetrafluorobenzoic acid, tetrachlorobenzoic acid, tetrabromobenzoic acid, tetraiodobenzoic acid, pentafluorobenzoic acid, pentachlorobenzoic acid, pentabromobenzoic acid, pentaiodobenzoic acid, fluoronaphthoic acid, chloronaphthoic acid, bromonaphthoic acid, iodonaphthoic acid Perfluoronaphthoic acid, perchloronaphthoic acid, perbromonaphthoic acid, periodonaphthoic acid, fluoroanthracene carboxylic acid, chloroanthracene carboxylic acid, bromoanthanthene carboxylic acid, Over de-anthracene carboxylic acid, perfluoro-anthracene carboxylic acid, perchlorethylene anthracene carboxylic acid, perfluoro-bromo-anthracene carboxylic acid, halogenated aromatic carboxylic acids such as per-iodo-anthracene carboxylic acid, benzoyl formic acid;

For example, alkyl aromatic carboxylic acids such as toluic acid and 2,4,6-tri (isopropyl) benzoic acid;
For example, 2-trifluoromethylbenzoic acid, 2-trichloromethylbenzoic acid, 2-tribromomethylbenzoic acid, 2-triiodomethylbenzoic acid, 3-trifluoromethylbenzoic acid, 3-trichloromethylbenzoic acid, 3- Tribromomethylbenzoic acid, 3-triiodomethylbenzoic acid, 4-trifluoromethylbenzoic acid, 4-trichloromethylbenzoic acid, 4-tribromomethylbenzoic acid, 4-triiodomethylbenzoic acid, 2-fluoro-4 -(Trifluoromethyl) benzoic acid, 2-chloro-4- (trichloromethyl) benzoic acid, 2-bromo-4- (tribromomethyl) benzoic acid, 2,3,4-trifluoro-6- (trifluoro Methyl) benzoic acid, 2,3,4-trichloro-6- (trichloromethyl) benzoic acid, 2,3,4-tribromo-6- ( (Ribromomethyl) benzoic acid, 2,3,4-triiodo-6- (triiodomethyl) benzoic acid, 2-iodo-4- (triiodomethyl) benzoic acid, 2,4-bis (trifluoromethyl) benzoic acid, 2,4-bis (trichloromethyl) benzoic acid, 2,4-bis (tribromomethyl) benzoic acid, 2,4-bis (triiodomethyl) benzoic acid, 2,6-bis (trifluoromethyl) benzoic acid 2,6-bis (trichloromethyl) benzoic acid, 2,6-bis (tribromomethyl) benzoic acid, 2,6-bis (triiodomethyl) benzoic acid, 3,5-bis (trifluoromethyl) benzoic acid Acid, 3,5-bis (trichloromethyl) benzoic acid, 3,5-bis (tribromomethyl) benzoic acid, 3,5-bis (triiodomethyl) benzoic acid, 2,4,6-tris (tri Fluoromethyl) benzoic acid, 2,4,6-tris (trichloromethyl) benzoic acid, 2,4,6-tris (tribromomethyl) benzoic acid, 2,4,6-tris (triiodomethyl) benzoic acid, 2, -Chloro-6-fluoro-3-methylbenzoic acid, trifluoromethylnaphthoic acid, trichloromethylnaphthoic acid, tribromomethylnaphthoic acid, triiodomethylnaphthoic acid,

Bis (trifluoromethyl) naphthoic acid, bis (trichloromethyl) naphthoic acid, bis (tribromomethyl) naphthoic acid, bis (triiodomethyl) naphthoic acid, tris (trifluoromethyl) naphthoic acid, tris (trichloromethyl) naphthoic acid Haloalkyl aromatics such as acids, tris (tribromomethyl) naphthoic acid, tris (triiodomethyl) naphthoic acid, trifluoromethylanthracene carboxylic acid, trichloromethylanthracene carboxylic acid, tribromomethylanthracene carboxylic acid, triiodomethylanthracene carboxylic acid Group carboxylic acids;
For example, an alkoxy aromatic carboxylic acid such as anisic acid, betramic acid, o-bertramic acid;
For example, 4-trifluoromethoxybenzoic acid, 4-trichloromethoxybenzoic acid, 4-tribromomethoxybenzoic acid, 4-triiodomethoxybenzoic acid, 4-pentafluoroethoxybenzoic acid, 4-pentachloroethoquinbenzoic acid, 4-pentabromoethoxybenzoic acid, 4-pentaiodoethoxybenzoic acid, 3,4-bis (trifluoromethoxy) benzoic acid, 3,4-bis (trichloromethoxy) benzoic acid, 3,4-bis (tribromomethoxy) ) Benzoic acid, 3,4-bis (triiodomethoxy) benzoic acid, 2,5-bis (2,2,2-trifluoroethoxy) benzoic acid, 2,5-bis (2,2,2-trichloroethoxy) ) Benzoic acid, 2,5-bis (2,2,2-tribromoethoxy) benzoic acid, 2,5-bis (2,2,2-triiodoethoxy) ) Haloalkoxy aromatic carboxylic acids such as benzoic acid;
For example, hydroxy aromatic carboxylic acids such as salicylic acid, o-pyrocatechuic acid, α-resorcylic acid, gentesic acid, α-resorcylic acid, protocatechuic acid, α-resorcylic acid, gallic acid and the like;
For example, hydroxyalkoxy aromatic carboxylic acids such as vanillic acid and isovanillic acid;
For example, nitroaromatic carboxylic acids such as trinitrobenzoic acid;
For example, an amino aromatic carboxylic acid such as anthranilic acid;
For example, α-toluic acid, hydrocinnamic acid, hydroatropic acid, 3-phenylpropionic acid, 4-phenylbutyric acid, 5-phenylpentanoic acid, 6-phenylhexanoic acid, 7-phenylheptanoic acid, 6- (2-naphthyl) Araliphatic carboxylic acids such as hexanoic acid;
For example, hydroxyaromatic carboxylic acids such as homogentisic acid;
For example, aromatic hydroxyalkyl carboxylic acids such as mandelic acid, benzylic acid, atrolactic acid, tropic acid, atroglyceric acid;
For example, 2-formylacetic acid, acetoacetic acid, 3-benzoylpropionic acid, 4-formylbutyric acid, 3-oxovaleric acid, 5-oxovaleric acid, 3,5-dioxovaleric acid, 6-formylhexanecarboxylic acid, 2 -Oxo-1-cyclohexanecarboxylic acid, 4- (2-oxobutyl) benzoic acid, p- (3-formylpropyl) benzoic acid, 4-formylphenylacetic acid, β-oxocyclohexanepropionic acid, pyruvic acid, and other oxocarboxylic acids Is mentioned.
Among these, benzoyl formic acid, acetic acid, and benzoic acid are particularly preferable.

  Specific examples of the specific sulfonium salt as described above are shown below by dividing them into a cation portion and an anion portion, but the present invention is not limited thereto. In addition, the cation part and the anion part shown below can be arbitrarily combined to form a specific sulfonium salt.

(Synthesis of specific sulfonium salt in the present invention)
The specific sulfonium salt used in the present invention can be synthesized by the following method.
First, a compound having a sulfonium salt structure containing an acid group can be generally synthesized by Friedel-Craft reaction or Grineer reaction of a sulfide compound and an aromatic compound. The synthesis method is described, for example, in J. Org. Amer. Chem. Soc. 112 (16), 1990; pp 6004-6015, J. MoI. Org. Chem. 1988; pp 5571-5573, WO 02/081439 A1 pamphlet, or European Patent (EP) No. 1113005. Subsequently, sulfonium salts containing acid groups are described in Protective Groups In Organic Synthesis (Second Edition) ”, Theodora W. Greene, Peter G. M. Wuts, John Wiley & Sons 91, published by John Wiley & Sons. Can be synthesized.

In the recording layer in the present invention, the content of the specific sulfonium salt is preferably 0.1 to 50% by mass in the total solid content of the recording layer from the viewpoint of sensitivity and soiling property of the non-image area. More preferably, it is 0.5-50 mass%, and it is especially preferable that it is 1-40 mass%.
In addition, specific sulfonium salt may be used individually by 1 type, and may use 2 or more types together.

In the recording layer of the present invention, a general onium salt other than the specific sulfonium salt can be used in combination as a dissolution inhibitor. Such general onium salts will be described in the following other components.
When the specific sulfonium salt and the general onium salt are used in combination, the general onium salt can be used in the range of 0 to 30% by mass with respect to the specific sulfonium salt, preferably 0.5 to It is in the range of 15% by mass.

[(A) Water-insoluble and alkali-soluble resin]
As the (A) water-insoluble and alkali-soluble resin (hereinafter, appropriately referred to as alkali-soluble resin) constituting the recording layer in the invention, an acid group is contained alone in the main chain and / or side chain in the polymer. Including polymers, copolymers thereof, or mixtures thereof.
Among these, those having an acidic group listed in the following (1) to (6) in the main chain and / or side chain of the polymer are preferable from the viewpoint of solubility in an alkaline developer and expression of dissolution inhibiting ability.

(1) Phenol group (-Ar-OH)
(2) sulfonamide group (-SO ₂ NH-R)
(3) Substituted sulfonamide acid group (hereinafter referred to as “active imide group”)
[—SO ₂ NHCOR, —SO ₂ NHSO ₂ R, —CONHSO ₂ R]
(4) Force rubonic acid group (—CO ₂ H)
(5) Sulfonic acid group (—SO ₃ H)
(6) Phosphate group (—OPO ₃ H ₂ )

  In the above (1) to (6), Ar represents a divalent aryl linking group which may have a substituent, and R represents a hydrogen atom or a hydrocarbon group which may have a substituent. .

  Among the alkali-soluble resins having an acidic group selected from the above (1) to (6), (1) an alkali-soluble resin having a phenol group, (2) a sulfonamide group, and (3) an active imide group is preferable. An alkali-soluble resin having (1) a phenol group or (2) a sulfonamide group is most preferred from the viewpoint of sufficiently ensuring solubility in an alkaline developer, development latitude, and film strength.

As alkali-soluble resin which has an acidic group chosen from said (1)-(6), the following can be mentioned, for example.
(1) Examples of the alkali-soluble resin having a phenol group include a condensation polymer of phenol and formaldehyde, a condensation polymer of m-cresol and formaldehyde, a condensation polymer of p-cresol and formaldehyde, m− / p. A novolac resin such as a condensation polymer of mixed cresol and formaldehyde, a condensation polymer of phenol and cresol (m-, p- or m- / p-mixed) and formaldehyde, and pyrogallol and acetone. Can be mentioned. Furthermore, the copolymer which copolymerized the compound which has a phenol group in a side chain can also be mentioned.

  Examples of the compound having a phenol group include acrylamide, methacrylamide, acrylic acid ester, methacrylic acid ester, and hydroxystyrene having a phenol group.

  (2) As an alkali-soluble resin having a sulfonamide group, for example, a polymer composed of a minimum constituent unit derived from a compound having a sulfonamide group as a main constituent can be mentioned. Examples of the compound as described above include compounds having at least one sulfonamide group in which at least one hydrogen atom is bonded to a nitrogen atom and one or more polymerizable unsaturated groups in the molecule. Among them, low molecular compounds having an acryloyl group, an allyl group, or a vinyloxy group, and a substituted or monosubstituted aminosulfonyl group or a substituted sulfonylimino group in the molecule are preferable. For example, the following general formulas (i) to ( and a compound represented by v).

[In formula, X < ¹ >, X < ² > represents -O- or NR < ⁷ > each independently. R ¹ and R ⁴ each independently represents a hydrogen atom or —CH ₃ . R ² , R ⁵ , R ⁹ , R ¹² , and R ¹⁶ each independently represent a C 1-12 alkylene group, cycloalkylene group, arylene group, or aralkylene group that may have a substituent. . R ³ , R ⁷ and R ¹³ each independently represent a hydrogen atom, an optionally substituted alkyl group having 1 to 12 carbon atoms, a cycloalkyl group, an aryl group or an aralkyl group. R ⁶ and R ¹⁷ each independently represents a C 1-12 alkyl group, cycloalkyl group, aryl group or aralkyl group which may have a substituent. R ⁸ , R ¹⁰ and R ¹⁴ each independently represent a hydrogen atom or —CH ₃ . R ^11, R ¹⁵ are each independently a single bond or may have a substituent group alkylene group having 1 to 12 carbon atoms, cycloalkylene group, arylene group, or aralkylene group. Y ¹ and Y ² each independently represents a single bond or CO. ]

  Among the compounds represented by the general formula (i) to the general formula (v), in the positive planographic printing plate precursor of the present invention, in particular, m-aminosulfonylphenyl methacrylate, N- (p-aminosulfonylphenyl) methacrylamide N- (p-aminosulfonylphenyl) acrylamide and the like can be preferably used.

  (3) As an alkali-soluble resin having an active imide group, for example, a polymer composed of a minimum constituent unit derived from a compound having an active imide group as a main constituent can be mentioned. Examples of the compound as described above include compounds each having one or more active imide groups represented by the following structural formula and polymerizable unsaturated groups in the molecule.

  Specifically, N- (p-toluenesulfonyl) methacrylamide, N- (p-toluenesulfonyl) acrylamide and the like can be preferably used.

(4) As an alkali-soluble resin having a strong rubonic acid group, for example, a minimum structural unit derived from a compound having at least one carboxylic acid group and polymerizable unsaturated group in the molecule is used as a main constituent component. Can be mentioned.
(5) As the alkali-soluble polymer having a sulfonic acid group, for example, a minimum structural unit derived from a compound having at least one sulfonic acid group and polymerizable unsaturated group in the molecule is a main structural unit. Can be mentioned.
(6) As an alkali-soluble resin having a phosphate group, for example, a minimum structural unit derived from a compound having at least one phosphate group and a polymerizable unsaturated group in the molecule is used as a main constituent component. A polymer can be mentioned.

  (A) The minimum structural unit having an acidic group selected from the above (1) to (6) that constitutes the alkali-soluble resin is not necessarily limited to one kind, and the minimum structural unit having the same acidic group Two or more kinds or those obtained by copolymerizing two or more kinds of minimum structural units having different acidic groups can also be used.

  The copolymer preferably contains 10 mol% or more of a compound having an acidic group selected from (1) to (6) to be copolymerized, and is contained in an amount of 20 mol% or more. Those are more preferred. If it is less than 10 mol%, the development latitude tends to be insufficiently improved.

In this invention, when alkali-soluble resin is a copolymer, the other compound which does not contain the acidic group of said (1)-(6) can also be used as a compound which comprises a copolymer. Examples of other compounds not containing an acidic group of (1) to (6) include the compounds listed in the following (m1) to (m12), but are not limited thereto.
(M1) Acrylic acid esters and methacrylic acid esters having an aliphatic hydroxyl group such as 2-hydroxyethyl acrylate or 2-hydroxyethyl methacrylate.
(M2) Alkyl acrylates such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, amyl acrylate, hexyl acrylate, octyl acrylate, benzyl acrylate, 2-chloroethyl acrylate, glycidyl acrylate, etc. .
(M3) methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, amyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, 2-chloroethyl methacrylate, glycidyl methacrylate, etc. Alkyl methacrylate.
(M4) Acrylamide, methacrylamide, N-methylol acrylamide, N-ethyl acrylamide, N-hexyl methacrylamide, N-cyclohexyl acrylamide, N-hydroxyethyl acrylamide, N-phenyl acrylamide, N-nitrophenyl acrylamide, N- Acrylamide or methacrylamide such as ethyl-N-phenylacrylamide.

(M5) Vinyl ethers such as ethyl vinyl ether, 2-chloroethyl vinyl ether, hydroxyethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, octyl vinyl ether, and phenyl vinyl ether.
(M6) Vinyl esters such as vinyl acetate, vinyl chloroacetate, vinyl butyrate and vinyl benzoate.
(M7) Styrenes such as styrene, α-methylstyrene, methylstyrene, chloromethylstyrene.
(M8) Vinyl ketones such as methyl vinyl ketone, ethyl vinyl ketone, propyl vinyl ketone, and phenyl vinyl ketone.
(M9) Olefins such as ethylene, propylene, isobutylene, butadiene and isoprene.
(M10) N-vinylpyrrolidone, acrylonitrile, methacrylonitrile and the like.
(M11) Unsaturated imides such as maleimide, N-acryloylacrylamide, N-acetylmethacrylamide, N-propionylmethacrylamide, N- (p-chlorobenzoyl) methacrylamide.
(M12) Unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic anhydride and itaconic acid.

  In the present invention, the alkali-soluble resin preferably has a phenolic hydroxyl group from the viewpoint of excellent image formability upon exposure with an infrared laser or the like, such as phenol formaldehyde resin, m-cresol formaldehyde resin, p-cresol formaldehyde. Preferred are novolak resins and pyrogallol acetone resins such as resins, m- / p-mixed cresol formaldehyde resins, phenol / cresol (any of m-, p-, or m- / p-mixed) mixed formaldehyde resins.

  Further, as an alkali-soluble resin having a phenolic hydroxyl group, as described in US Pat. No. 4,123,279, a carbon number of 3 such as t-butylphenol formaldehyde resin and octylphenol formaldehyde resin is used. And a condensation polymer of phenol and formaldehyde having an alkyl group of ˜8 as a substituent.

  The alkali-soluble resin preferably has a weight average molecular weight of 500 or more from the viewpoint of image forming properties, and more preferably 1,000 to 700,000. Moreover, it is preferable that the number average molecular weight is 500 or more, and it is more preferable that it is 750-650,000. The dispersity (weight average molecular weight / number average molecular weight) is preferably 1.1 to 10.

  Moreover, these alkali-soluble resins may be used alone or in combination of two or more. In the case of combination, the number of carbon atoms such as a condensation polymer of t-butylphenol and formaldehyde or a condensation polymer of octylphenol and formaldehyde as described in US Pat. No. 4,123,279 is described. Combined use of a polycondensation product of phenol and formaldehyde having 3 to 8 alkyl groups as substituents, and an alkali-soluble resin having a phenol structure having an electron-withdrawing group on an aromatic ring described in JP-A-2000-241972 May be.

  In the recording layer of the present invention, the content of the alkali-soluble resin is preferably from 30 to 98% by mass, and preferably from 40 to 95% by mass in the total solid content of the recording layer, from the viewpoints of sensitivity, image formability, and film durability. Is more preferable.

[(B) Infrared absorber]
The (B) infrared absorber constituting the recording layer in the present invention can be used without particular limitation as long as it is a substance that absorbs an infrared laser used for recording and generates heat. From the viewpoint of compatibility with a laser, an infrared absorbing dye or pigment having an absorption maximum at a wavelength of 760 nm to 1200 nm is preferable.

  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, azo dyes, metal complex salt ab dyes, pyrablon azo dyes, naphthoquinone dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinoneimine dyes, methine dyes, cyanine dyes, squarylium dyes, pyrylium salts, metal thiolate complexes, oxonol dyes, Examples include dyes such as diimonium dyes, aminium dyes, and croconium dyes.

  Preferred dyes include, for example, cyanine dyes described in JP-A-58-125246, JP-A-59-84356, JP-A-59-202829, JP-A-60-78787, and the like. Methine dyes described in JP-A-58-173696, JP-A-58-181690, JP-A-58-194595, JP-A-58-112793, JP-A-58-224793, JP-A-59- 48187, JP-A 59-73996, JP-A 60-52940, JP-A 60-63744, etc., naphthoquinone dyes, JP-A 58-112792, etc. And cyanine dyes described in British Patent 434,875.

  Also, a near infrared absorption sensitizer described in US Pat. No. 5,156,938 is preferably used, and a substituted arylbenzo (thio) pyrylium salt described in US Pat. No. 3,881,924, Trimethine thiapyrylium salts described in JP-A-57-142645 (US Pat. No. 4,327,169), JP-A-58-181051, 58-220143, 59-41363, 59-84248 Nos. 59-84249, 59-146063, 59-146061, pyranlium compounds, cyanine dyes described in JP-A-59-216146, US Pat. No. 4,283,475 The pentamethine thiopyrylium salts described above and the pyrylium compounds disclosed in Japanese Patent Publication Nos. 5-13514 and 5-19702 are also preferably used. .

  Another example of a preferable dye is a near-infrared absorbing dye described in US Pat. No. 4,756,993 as formulas (I) and (II).

  Particularly preferred among these dyes are cyanine dyes, phthalocyanine dyes, oxonol dyes, squarylium dyes, pyrylium salts, thiopyrylium dyes, and nickel thiolate complexes. Further, the dyes represented by the following general formulas (a) to (e) are preferable because they are excellent in photothermal conversion efficiency. Particularly, the cyanine dyes represented by the following general formula (a) are used in the recording layer in the invention. In this case, it is most preferable because it gives a high interaction with the alkali-soluble resin and is excellent in stability and economy.

In formula (a), 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 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 a carbon atom having 1 to 12 carbon atoms including a hetero atom. Indicates a hydrogen group. In addition, a hetero atom here shows N, S, O, a halogen atom, and Se.

In the above formula, Xa ^- has Za described later ^- is defined as for, Ra 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 represents a hydrocarbon group having 1 to 12 carbon atoms. From the 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 hydrocarbon group which may have a substituent. Preferred aromatic hydrocarbon groups include a benzene ring and a naphthalene ring. Moreover, as a preferable substituent, a C12 or less hydrocarbon group, a halogen atom, and a C12 or less alkoxy group are mentioned. 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. Preferred substituents include alkoxy groups having 12 or less carbon atoms, carboxyl groups, and sulfo groups. 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. Za ⁻ represents a counter anion. However, Za ⁻ is not necessary when the cyanine dye represented by formula (a) has an anionic substituent in the structure and neutralization of charge is not necessary. Preferred Za ⁻ is a halogen ion, a perchlorate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, and a sulfonate ion, particularly preferably a perchlorate ion, a hexagonal salt, in view of the storage stability of the recording layer coating solution. Fluorophosphate ions and aryl sulfonate ions.

  Specific examples of the cyanine dye represented by formula (a) that can be suitably used in the present invention include those exemplified below, and paragraph numbers [0017] to [0019] of JP-A-2001-133969. And those described in paragraph numbers [0012] to [0038] of JP-A No. 2002-40638 and paragraph numbers [0012] to [0023] of JP-A No. 2002-23360.

In the general formula (b), L represents a methine chain having 7 or more conjugated carbon atoms, the methine chain may have a substituent, and the substituents are bonded to each other to form a ring structure. Also good. Zb ⁺ represents a counter cation. Preferred counter cations include ammonium, iodonium, sulfonium, phosphonium, pyridinium, alkali metal cations (Na ⁺ , K ⁺ , Li ⁺ ) and the like. R ^{9 to} R ¹⁴ and R ^{15 to} R ²⁰ are each independently a hydrogen atom or halogen atom, cyano group, alkyl group, aryl group, alkenyl group, alkynyl group, carbonyl group, thio group, sulfonyl group, sulfinyl group, oxy group Or a substituent selected from amino groups, or a combination of two or three of these, and may be bonded to each other to form a ring structure. Here, in the general formula (b), those in which L represents a methine chain having 7 conjugated carbon atoms and those in which R ^{9 to} R ¹⁴ and R ^{15 to} R ²⁰ all represent hydrogen atoms are easily available. From the viewpoint of the effect.

  Specific examples of the dye represented by formula (b) that can be suitably used in the present invention include those exemplified below.

In the general formula (c), Y ³ and Y ⁴ each represent an oxygen atom, a sulfur atom, a selenium atom, or a tellurium atom. M represents a methine chain having 5 or more conjugated carbon atoms. R ^{21 to} R ²⁴ and R ^{25 to} R ²⁸ may be the same or different, and are each a hydrogen atom, a halogen atom, a cyano group, an alkyl group, an aryl group, an alkenyl group, an alkynyl group, a carbonyl group, a thiol group, Represents a group, a sulfonyl group, a sulfinyl group, an oxy group, or an amino group. Further, wherein Za ^- include a counter anion, Za in the general formula (a) ^- it is synonymous.

  In the present invention, specific examples of the dye represented by formula (c) that can be suitably used include those exemplified below.

In the general formula (d), R ²⁹ to R ³¹ each independently represent a hydrogen atom, an alkyl group, or an aryl group. R ³³ and R ³⁴ each independently represents an alkyl group, a substituted oxy group, or a halogen atom. n and m each independently represents an integer of 0 to 4. R ²⁹ and R ³⁰ , or R ³¹ and R ³² may be bonded to each other to form a ring, and R ²⁹ and / or R ³⁰ is R ³³ and R ³¹ and / or R ³² is R ³⁴ taken together, may form a ring, further, when R ³³ or R ³⁴ there are a plurality, R ³³ or between R ³⁴ each other may be bonded to each other to form a ring. X ² and X ³ each independently represent a hydrogen atom, an alkyl group, or an aryl group, and at least one of X ² and X ³ represents a hydrogen atom or an alkyl group. Q is a trimethine group or a pentamethine group which may have a substituent, and may form a ring structure together with a divalent organic group. Zc ⁻ represents a counter anion and has the same meaning as Za ⁻ in the general formula (a).

  In the present invention, specific examples of the dye represented by the general formula (d) that can be suitably used include those exemplified below.

In the general formula (e), R ^{35 to} R ⁵⁰ are each independently a hydrogen atom, a halogen atom, a cyano group, an alkyl group, an aryl group, an alkenyl group, an alkynyl group, a hydroxyl group, a carbonyl group, a thio group, or a sulfonyl group. , A sulfinyl group, an oxy group, an amino group, and an onium salt structure, and may further have a substituent depending on the structure. M represents two hydrogen atoms or metal atoms, a halometal group, and an oxymetal group, and the metal atoms contained therein are IA, IIA, IIIB, IVB group atoms of the periodic table, first, second, second Three-period transition metals and lanthanoid elements can be mentioned, among which copper, magnesium, iron, zinc, cobalt, aluminum, titanium, and vanadium are preferable.

  In the present invention, specific examples of the dye represented by formula (e) that can be suitably used include those exemplified below.

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

  Examples of the pigment include black pigment, yellow pigment, orange pigment, brown pigment, red pigment, purple pigment, blue pigment, green pigment, fluorescent pigment, metal powder pigment, and polymer-bonded dye. Specifically, insoluble azo pigments, azo lake pigments, condensed azo pigments, chelate azo pigments, phthalocyanine pigments, anthraquinone pigments, perylene and perinone pigments, thioindigo pigments, quinacridone pigments, dioxazine pigments, isoindolinone pigments A quinophthalone pigment, a dyed lake pigment, an azine pigment, a nitroso pigment, a nitro pigment, a natural pigment, a fluorescent pigment, an inorganic pigment, or carbon black can be used.

  These pigments may be used without surface treatment or may be used after surface treatment. Examples of the surface treatment method include a method of surface coating with a resin or wax, a method of attaching a surfactant, and a method of bonding a reactive substance (eg, silane coupling agent, epoxy compound, polyisocyanate) to the pigment surface. It is done. 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 diameter 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, from the viewpoint of the dispersion stability in the coating liquid and the uniformity of the recording layer. It is particularly preferable that the thickness is in the range of 0.1 μm to 1 μm.

  As a method for dispersing the pigment, a known dispersion technique used in 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).

The infrared absorber may be added to the same layer as the recording layer, or another layer may be provided and added thereto. In the case of a separate layer, it is desirable to add it to a layer adjacent to the recording layer.
Further, when the infrared absorbent is a compound having dissolution inhibiting ability, it is added to the same layer as the (A) alkali-soluble resin, so that the infrared absorbent has not only a photothermal conversion function but also a development inhibitor. Is also preferable.

  In the recording layer of the present invention, the content of the infrared absorber is preferably 0.01 to 50% by mass in the total solid content of the recording layer from the viewpoints of sensitivity and durability (film properties) of the recording layer. More preferably, 0.1 to 10% by mass is added. In the case of a dye, it is particularly preferably 0.5 to 10% by mass, and in the case of a pigment, it is particularly preferably 0.1 to 10% by mass.

[Other ingredients]
In forming the recording layer in the present invention, various additives can be added as necessary, in addition to the above components, as long as the effects of the present invention are not impaired.

[Dissolution inhibitor]
In addition to the specific sulfonium salt, the recording layer in the present invention preferably contains a dissolution inhibitor for the purpose of enhancing inhibition (dissolution suppression ability). As the dissolution inhibitor, for example, an onium salt, an o-quinonediazide compound, an aromatic sulfone compound, an aromatic sulfonic acid ester compound and the like are thermally decomposable, and in a state where they are not decomposed, the solubility of the alkali-soluble resin is substantially reduced. It is preferable to use a substance that lowers the concentration of the toner in order to improve the dissolution inhibition property of the image portion in the developer.

Examples of the onium salt used in the present invention include conventionally known ones such as a diazonium salt, an ammonium salt, a phosphonium salt, an iodonium salt, a sulfonium salt, a selenonium salt, and an arsonium salt. The following are mentioned.
S. I. Schlesinger, Photogr. Sci. Eng. , 18, 387 (1974), T.A. S. A diazonium salt described in Balet al, Polymer, 21, 423 (1980), JP-A-5-158230;
Ammonium salts described in U.S. Pat. Nos. 4,069,055, 4,069,056 and JP-A-3-140140; C. Necker et al, Macromolecules, 17, 2468 (1984), C.I. S. Wen et al, Teh, Proc. Conf. Rad. Curing ASIA, p478 Tokyo, Oct (1988), U.S. Pat. Nos. 4,069,055 and 4,069,056,

  J. et al. V. Crivello et al, Macromolecules, 10 (6), 1307 (1977), Chem. & Eng. News, Nov. 28, p31 (1988), European Patent No. 104,143, US Pat. Nos. 5,041,358, 4,491,628, JP-A-2-150848 and JP-A-2-296514. Iodonium salt,

  J. et al. V. Crivello et al, Polymer J. et al. 17, 73 (1985), J. Am. V. Crivello et al. J. et al. Org. Chem. 48, 3055 (1978); R. Watt et al, J.A. Polymer Sci. , Polymer Chem. Ed. , 22, 1789 (1984), J. Am. V. Crivello et al, Polymer Bull. 14, 279 (1985), J. Am. V. Crivello et al, Macromolecules, 14 (5), 1141 (1981), J. MoI. V. Crivello et al, J.A. Polymer Scl. , Polymer Chem. Ed. 17, 2877 (1979), European Patents 370,693, 233,567, 297,443, 297,442, U.S. Pat. Nos. 4,933,377, 3,902,114 No. 4,491,628, No. 4,760,013, No. 4,734,444, No. 2,833,827, German Patent No. 2,904,626, No. 3,604 The sulfonium salt described in No. 580 and No. 3,604,581,

J. et al. V, Crivello et al, MacromoreCules, lo (6), 1307 (1977), J. MoI. V. Crivello et al, J.A. Polymer Sci. , Polymer Chem. Ed. , 17, 1047 (1979), selenonium salts,
C. S. Wen et al, Teh, Proc. Conf. Rad. Curing ASIA, p478 Tokyo, Oct (1988).
Of these onium salts, diazonium salts are particularly preferred. Particularly suitable diazonium salts include those described in JP-A-5-158230.

  The counter ion of the onium salt includes tetrafluoroboric acid, hexafluorophosphoric acid, triisopropylnaphthalenesulfonic acid, 5-nitro-o-toluenesulfonic acid, 5-sulfosalicylic acid, 2,5-dimethylbenzenesulfonic acid, 2,4,6-trimethylbenzenesulfonic acid, 2-nitrobenzenesulfonic acid, 3-chlorobenzenesulfonic acid, 3-bromobenzenesulfonic acid, 2-fluorocaprylnaphthalenesulfonic acid, dodecylbenzenesulfonic acid, 1-naphthol-5-sulfone Examples include acid, 2-methoxy-4-hydroxy-5-benzoyl-benzenesulfonic acid, and paratoluenesulfonic acid. Of these, alkyl aromatic sulfonic acids such as hexafluorophosphoric acid, triisopropylnaphthalenesulfonic acid and 2,5-dimethylbenzenesulfonic acid are particularly preferred.

The addition amount of these onium salts is preferably in the range of 0.1 to 40% by mass, more preferably 0.1 to 30% by mass, and still more preferably 0.1 to 25% by mass with respect to the total solid content of the recording layer. It is.
These onium salts can be used alone, but may be used as a mixture of several kinds.

Suitable quinonediazides include o-quinonediazide compounds. The o-quinonediazide compound used in the present invention is a compound having at least one o-quinonediazide group, which increases alkali solubility by thermal decomposition, and compounds having various structures can be used. That is, o-quinonediazide assists the solubility of the upper layer by the effects of both losing the inhibition as a development inhibitor due to thermal decomposition and changing o-quinonediazide itself into an alkali-soluble substance.
Examples of such o-quinonediazide compounds include J. Org. The compounds described in pages 339-352 of “Light-Sensitive Systems” (John Wiley & Sons. Inc.) by Korser can be used. Sulfonic acid esters or sulfonic acid amides are preferred. Further, benzoquinone (1,2) -diazide sulfonic acid chloride or naphthoquinone- (1,2) -diazide-5-sulfonic acid chloride and pyrogallol-acetone resin as described in JP-B-43-28403 Esters of benzoquinone- (1,2-diazide sulfonic acid chloride or naphthoquinone- (1,2) -diazide-5 described in US Pat. Nos. 3,046,120 and 3,188,210. Esters of sulfonic acid chloride and phenol-formaldehyde resin are also preferably used.

  Further, esters of naphthoquinone- (1,2) -diazido-4-sulfonic acid chloride with phenol formaldehyde resin or cresol-formaldehyde resin, naphthoquinone- (1,2) -diazido-4-sulfonic acid chloride and pyrogallol-acetone resin Similarly, the esters are also preferably used. Other useful o-quinonediazide compounds are reported and known in numerous patents. For example, JP-A-47-5303, JP-A-48-63802, JP-A-48-63803, JP-A-48-96575, JP-A-49-38701, JP-A-48-13354, Japanese Patent Publication Nos. 41-11222, 45-9610, 49-17474, U.S. Pat. Nos. 2,797,213, 3,454,400, 3,544,323, 3,573,917, 3,674,495, 3,785,825, British Patents 1,227,602, 1,251,345, 1,267, No. 005, No. 1,329,888, No. 1,330,932, German Patent No. 854,890, and the like.

The addition amount of the o-quinonediazide compound is preferably in the range of 0.1 to 8% by mass, more preferably 0.2 to 5% by mass, based on the total solid content of the recording layer. These compounds can be used alone, but may be used as a mixture of several kinds.
Further, an alkali-soluble resin at least partially esterified in JP-A No. 11-288089 may be included.

[Development accelerator]
For the purpose of improving sensitivity, acid anhydrides, phenols, and organic acids may be added to the recording layer in the present invention.
As the acid anhydrides, cyclic acid anhydrides are preferable, and specific examples of cyclic acid anhydrides include phthalic anhydride, tetrahydrophthalic anhydride, and hexahydro anhydride described in US Pat. No. 4,115,128. Uses phthalic acid, 3,6-endooxy-Δ ⁴ -tetrahydrophthalic anhydride, tetrachlorophthalic anhydride, maleic anhydride, chloromaleic anhydride, α-phenylmaleic anhydride, succinic anhydride, pyromellitic anhydride, etc. it can. Examples of the acyclic acid anhydride include acetic anhydride.

  Examples of phenols include bisphenol A, 2,2′-bishydroxysulfone, p-nitrophenol, p-ethoxyphenol, 2,4,4′-trihydroxybenzophenone, 2,3,4-trihydroxybenzaphenone, 4 Hydroquinobenzophenone, 4,4 ′, 4 ″ -trihydroxytriphenylmethane, 4,4 ′, 3 ″, 4 ″ -tetrahydroxy-3,5,3 ′, 5′-tetramethyltriphenylmethane, 4 , 4'-sulfonyldiphenol and the like.

Examples of organic acids include sulfonic acids, sulfinic acids, alkylsulfuric acids, phosphonic acids, phosphate esters, and carboxylic acids described in JP-A-60-88942 and JP-A-2-96755. Specifically, p-toluenesulfonic acid, dodecylbenzenesulfonic acid, p-toluenesulfinic acid, ethyl sulfate, phenylphosphonic acid, phenylphosphinic acid, phenyl phosphate, diphenyl phosphate, benzoic acid, isophthalic acid, adipic acid , P-toluic acid, 3,4-dimethoxybenzoic acid, phthalic acid, terephthalic acid, 4-cyclohexene-1,2-dicarboxylic acid, erucic acid, lauric acid, n-undecanoic acid, ascorbic acid and the like.
The proportion of the acid anhydride, phenols and organic acids in the total solid content of the recording layer is preferably 0.05 to 20% by mass, more preferably 0.1 to 15% by mass, particularly preferably 0.1 to 0.1% by mass. 10% by mass.

[Surfactant]
The recording layer in the present invention is described in JP-A Nos. 62-251740 and 3-208514 in order to improve the coating properties and to expand the stability of processing with respect to development conditions. Such nonionic surfactants, amphoteric surfactants as described in JP-A-59-121044 and JP-A-4-13149, siloxane compounds as described in EP950517, A fluorine-containing monomer copolymer as described in JP-A-62-170950, JP-A-11-288093, and Japanese Patent Application No. 2001-247351 can be added.

Specific examples of the nonionic surfactant include sorbitan tristearate, sorbitan monopalmitate, sorbitan trioleate, stearic acid monoglyceride, and polyoxin ethylene nonylphenyl ether.
Specific examples of amphoteric activators include alkyldi (aminoethyl) glycine, alkylpolyaminoethylglycine hydrochloride, 2-alkyl-N-carboxyethyl-N-hydroxyethylimidazolinium betaine and N-tetradecyl-N, N-to. Examples include tine type (for example, trade name “Amorgen K” manufactured by Daiichi Kogyo Seiyaku Co., Ltd.).

As the siloxane compound, a block copolymer of dimethylsiloxane and polyalkylene oxide is preferable. Specific examples include DBE-224, DBE-621, DBE-712, DBP-732, DBP-534, manufactured by Chisso Corporation. And polyalkylene oxide-modified silicones such as Tego Glide 100 manufactured by Tego, Germany.
The proportion of the nonionic surfactant and amphoteric surfactant in the total solid content of the recording layer is preferably 0.01 to 15% by mass, more preferably 0.1 to 5.0% by mass, and still more preferably 0.8. 5 to 2.0% by mass.

[Bake-out agent / colorant]
In the recording layer of the present invention, a print-out agent for obtaining a visible image immediately after heating by exposure, or a dye or pigment as an image colorant can be added.
A representative example of the printing-out agent is a combination of a compound that releases an acid by heating by exposure (photoacid releasing agent) and an organic dye that can form a salt. Specifically, combinations of o-naphthoquinonediazide-4-sulfonic acid halides and salt-forming organic dyes described in JP-A-50-36209 and JP-A-53-8128, 36223, 54-74728, 60-3626, 61-143748, 61-151644 and 63-58440, and trihalomethyl compounds and salt-forming organic dyes Can be mentioned. Such trihalomethyl compounds include oxazole compounds and triazine compounds, both of which have excellent temporal stability and give clear printout images.

As the image colorant, other dyes can be used in addition to the aforementioned salt-forming organic dyes. Examples of suitable dyes including salt-forming organic dyes include oil-soluble dyes and basic dyes. 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 (oriental chemical industry) Co., Ltd.), Victoria Pure Blue, Crystal Violet Lactone, Crystal Violet (CI42555), Methyl Violet (CI42535), Ethyl Violet, Rhodamine B (CI145170B), Malachite Green (CI42000), Methylene Blue (CI52015), etc. it can. The dyes described in JP-A-62-293247 are particularly preferred.
These dyes can be added in a proportion of 0.01 to 10% by mass, preferably 0.1 to 3% by mass, based on the total solid content of the recording layer.

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

[WAX agent]
A compound that lowers the coefficient of static friction of the surface can also be added to the recording layer in the present invention for the purpose of imparting resistance to scratches. Specifically, US Pat. No. 6,117,913 or Japanese Patent Application Nos. 2001-261627, 2002-032904, and 2002-165854 previously proposed by the applicant of the present application. And compounds having an ester of a long-chain alkyl carboxylic acid as described in 1).
The added amount of these WAX agents is preferably 0.1 to 10% by mass, and more preferably 0.5 to 5% by mass in the total solid content of the recording layer.

[Formation of recording layer]
The recording layer in the lithographic printing plate precursor according to the invention may be formed by dissolving the above components in a solvent to prepare a coating solution and coating the coating solution on a suitable support. Depending on the purpose, a backcoat layer, an undercoat layer, an organic intermediate layer, and the like can be formed in the same manner.
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, and toluene. It is not limited. These solvents are used alone or in combination.
Here, the density | concentration of the said component (particulate form containing an additive) in a coating liquid becomes like this. Preferably it is 1-50 mass%.
The coating amount (solid content) on the support obtained after coating and drying is generally preferably 0.5 to 5.0 g / m ² from the viewpoints of sensitivity and film properties.

  The recording layer in the lithographic printing plate precursor according to the invention may be a single layer or may have a multilayer structure composed of a plurality of layers having different constituent components. In the case of a recording layer having a multilayer structure, an embodiment in which a specific sulfonium salt is added to the uppermost layer is preferable from the viewpoint of the effect of addition.

[Support]
It is essential that the support used in the present invention has a hydrophilic surface. The support suitable for the present invention is not particularly limited as long as it is a dimensionally stable plate having the required strength and durability, and a plate subjected to a hydrophilization treatment is used. It is done.
Examples of the plate-like material suitable for the support include, 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.) Or a plastic film.

  Among them, in the present invention, a polyester film or an aluminum plate is preferable, and among them, an aluminum plate that has good dimensional stability and is relatively inexpensive is particularly preferable. A suitable aluminum plate is a pure aluminum plate or an alloy plate containing aluminum as a main component and containing a trace amount of different elements, and may be a plastic film on which aluminum is laminated or vapor-deposited. 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 at most 10% by mass.

Particularly suitable aluminum in the present invention is pure aluminum. However, since completely pure aluminum is difficult to manufacture in terms of refining technology, it may contain slightly different elements.
Thus, the composition of the aluminum plate applied to the present invention is not specified, and an aluminum plate made of a publicly known material can be appropriately used. The thickness of the aluminum plate used in the present invention is about 0.1 mm to 0.6 mm, preferably 0.15 mm to 0.4 mm, and particularly preferably 0.2 mm to 0.3 mm.

Such an aluminum plate is preferably subjected to surface treatment (including hydrophilization treatment) such as roughening treatment and anodizing treatment as described below.
Prior to roughening the aluminum plate, a degreasing treatment with, for example, a surfactant, an organic solvent, or an alkaline aqueous solution 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, a method of mechanically roughening, a method of electrochemically dissolving and roughening a surface, and a method of selectively dissolving a surface chemically. This is done by the method of As the mechanical method, a known method such as a ball polishing method, a bran polishing method, a blast polishing method, or a buff polishing method can be used. Further, as an electrochemical surface roughening method, there is a method of performing alternating current or direct current in hydrochloric acid or nitric acid electrolyte. Further, as disclosed in JP-A-54-63902, a method in which both are combined can also be used.
The aluminum plate roughened as described above is subjected to an alkali etching treatment and neutralization treatment as necessary, and then subjected to an anodizing treatment if desired in order to enhance the water retention and wear resistance of the surface. 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, phosphoric 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 treatment conditions for anodization vary depending on the electrolyte used, and thus 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 / dm ^2. A voltage of 1 to 100 V and an electrolysis time of 10 seconds to 5 minutes are suitable. If the amount of the anodized film is less than 1.0 g / m ² , the printing durability will be insufficient, or the non-image part of the planographic printing plate will be easily damaged, and ink will adhere to the damaged part during printing. The so-called “scratch stain” tends to occur.
After the anodizing treatment, the aluminum surface is subjected to a hydrophilic treatment if necessary.

  The hydrophilization treatment used in the present invention is disclosed in US Pat. Nos. 2,714,066, 3,181,461, 3,280,734 and 3,902,734. There are alkali metal silicate (such as aqueous sodium silicate) methods. In this method, the support is immersed in an aqueous sodium silicate solution or electrolytically treated. In addition, potassium fluoride zirconate disclosed in Japanese Patent Publication No. 36-22063 and disclosed in US Pat. Nos. 3,276,868, 4,153,461 and 4,689,272 A method of treating with polyvinylphosphonic acid as described above is used.

[Back coat layer]
A back coat layer is provided on the back side of the support of the planographic printing plate precursor according to the invention, if necessary. Such a back coat layer comprises a metal oxide obtained by hydrolysis and polycondensation of an organic polymer compound described in JP-A-5-45885 and an organic or inorganic metal compound described in JP-A-6-35174. A coating layer is preferably used. Among these coating layers, silicon alkoxy compounds such as Si (OCH ₃ ) ₄ , Si (OC ₂ H ₅ ) ₄ , Si (OC ₃ H ₇ ) ₄ , and Si (OC ₄ H ₉ ) ₄ are available at a low price. The coating layer of the metal oxide obtained therefrom is particularly preferable because of its excellent developer resistance.

(Undercoat layer)
In the lithographic printing plate precursor according to the invention, an undercoat layer can be provided between the support and the recording layer, if necessary.
Various organic compounds are used as the undercoat layer component. For example, phosphonic acids having an amino group such as carboxymethylcellulose, dextrin, gum arabic, 2-aminoethylphosphonic acid, phenylphosphonic acid which may have a substituent, Organic phosphonic acids such as naphthylphosphonic acid, alkylphosphonic acid, glycerophosphonic acid, methylenediphosphonic acid and ethylenediphosphonic acid, optionally substituted phenylphosphoric acid, naphthylphosphonic acid, alkylphosphoric acid and glycerophosphoric acid Organic phosphoric acid, optionally substituted phenylphosphinic acid, naphthylphosphinic acid, organic phosphinic acids such as alkylphosphinic acid and glycerophosphinic acid, amino acids such as glycine and β-alanine, and hydrochloride of triethanolamine Hydroxy groups such as Selected from hydrochloride of the amine to be, but may be used by mixing two or more.

  The undercoat layer preferably contains a compound having an onium group. The compounds having an onium group are described in detail in JP-A Nos. 2000-10292 and 2000-108538. In addition, a compound selected from the group of polymer compounds having a structural unit represented by poly (p-vinylbenzoic acid) in the molecule can also be used. Specific examples of these polymer compounds include a copolymer of p-vinylbenzoic acid and vinylbenzyltriethylammonium salt, a copolymer of p-vinylbenzoic acid and vinylbenzyltrimethylammonium chloride, and the like. .

This organic undercoat layer can be provided by the following method. That is, a method in which water or an organic solvent such as methanol, ethanol, methyl ethyl ketone, or a mixed solvent thereof is dissolved and applied on an aluminum plate and dried, and water, methanol, ethanol, methyl ethyl ketone, etc. In this method, an aluminum plate is immersed in a solution in which the above organic compound is dissolved in the above organic solvent or a mixed solvent thereof to adsorb the above compound, and then washed with water or the like and dried to provide an organic undercoat layer. In the former method, a solution having a concentration of 0.005 to 10% by mass of the above organic compound can be applied by various methods. In the latter method, the concentration of the solution is 0.01 to 20% by mass, preferably 0.05 to 5% by mass, the immersion temperature is 20 to 90 ° C., preferably 25 to 50 ° C., and the immersion time is 0.1 second to 20 minutes, preferably 2 seconds to 1 minute. The solution used for this can be adjusted to a pH range of 1 to 12 with basic substances such as ammonia, triethylamine, potassium hydroxide, and acidic substances such as hydrochloric acid and phosphoric acid. Further, a yellow dye can be added to improve the tone reproducibility of the lithographic printing plate precursor.
The coverage of the organic undercoat layer, from the viewpoint of printing durability, 2 to 200 mg / m ² are suitable, and preferably from 5 to 100 mg / m ^2.

(Resin intermediate layer)
In the lithographic printing plate precursor according to the invention, an organic intermediate layer can be provided between the support and the recording layer as necessary.
By providing this organic intermediate layer, a recording layer, which is an infrared sensitive layer whose solubility in an alkali developer is improved by exposure, is provided on the exposed surface or in the vicinity thereof, thereby ensuring good sensitivity to an infrared laser. In addition, an organic intermediate layer made of a polymer existing between the support and the infrared sensitive layer functions as a heat insulating layer, and heat generated by infrared laser exposure is not diffused to the support, so that an image can be formed efficiently. Since it is used for the reaction, there is an advantage that it is possible to further increase the sensitivity. Further, in the unexposed area, the recording layer itself impermeable to the alkali developer functions as a protective layer for the organic intermediate layer, so that an image having excellent development stability and excellent discrimination is obtained. In the exposed area, the components of the recording layer whose dissolution-inhibiting ability is released are quickly dissolved and dispersed in the developer, and further supported. Since the organic intermediate layer that is adjacent to the body is made of an alkali-soluble polymer, the solubility in a developer is good. For example, even when a developer with reduced activity is used, a residual film or the like is present. It dissolves rapidly without generating and has excellent developability. That is, this organic intermediate layer is considered useful because it contributes to both the strength and development resistance of the image area and the ease of development in the non-image area.

  The organic intermediate layer preferably contains a water-insoluble and alkali-soluble resin (hereinafter referred to as an alkali-soluble resin as appropriate). As such an alkali-soluble resin, it is necessary for the organic intermediate layer itself to exhibit high alkali-solubility, particularly in the non-image area, and therefore it is necessary to select a resin that does not impair this property. From this viewpoint, (A) water-insoluble and alkali-soluble resins constituting the recording layer are preferably mentioned. Among these, from the viewpoint of sensitivity and image formability, it is preferable to select a resin that hardly forms an interaction and has excellent solubility in an alkaline developer. For example, a polyamide resin, an epoxy resin, an acetal resin, an acrylic resin Preferred examples include resins, methacrylic resins, styrene resins, urethane resins, and the like.

  As the alkali-soluble resin used for the organic intermediate layer, it is important to select a resin that is difficult to dissolve in the coating solvent when the recording layer is applied. By selecting such a resin, undesired compatibility at the interface between the two layers is suppressed, and further improvement in chemical resistance can be expected. From such a viewpoint, among the above, acrylic resin is particularly preferable.

Hereinafter, a water-insoluble and alkali-soluble acrylic resin (hereinafter, simply referred to as “acrylic resin” as appropriate), which is a preferable alkali-soluble resin suitably used for the organic intermediate layer, will be described. The acrylic resin used here is not particularly limited as long as it is insoluble in water and soluble in an alkaline aqueous solution. Such an acrylic resin is particularly suitable for forming such a multilayer structure because of its low compatibility with an alkali-soluble resin having a phenolic hydroxyl group that is preferably used in the recording layer. Excellent solubility.
Examples of the acrylic resin include a sulfonamide group (—SO ₂ NH—R, where R represents a hydrogen atom or a hydrocarbon group which may have a substituent), an active imide group [—SO ₂ NHCOR. , —SO ₂ NHSO ₂ R, —CONHSO ₂ R, where R represents a hydrogen atom or a hydrocarbon group which may have a substituent. ], Having an alkali-soluble group such as a carboxylic acid group (—CO ₂ H), a sulfonic acid group (—SO ₃ H), and a phosphoric acid group (—OPO ₃ H ₂ ), and being copolymerizable with an alkali-soluble resin Acrylic acid esters having aliphatic hydroxyl groups and methacrylic acid esters, alkyl acrylates, alkyl methacrylates, acrylamide or methacrylamide, alkyl maleimides, aryl maleimides and other inert imides, acrylonitrile, methacrylo Examples thereof include resins containing nitriles such as nitriles as constituent components. Also, acrylic resins having a sulfonamide group described in JP-A-2-866 can be suitably applied to the present invention.

  The acrylic resin preferably has a weight average molecular weight of 2,000 or more and a number average molecular weight of 500 or more. More preferably, the weight average molecular weight is 5,000 to 300,000, the number average molecular weight is 800 to 250,000, and the dispersity (weight average molecular weight / number average molecular weight) is 1.1 to 10. .

The content of the alkali-soluble resin in the organic intermediate layer component in the present invention is about 40 to 95% by weight, preferably about 50 to 90% by weight, based on the total solid content.
In such an organic intermediate layer, in addition to the alkali-soluble resin, a photothermal conversion agent used in the recording layer and various additives can be used in combination.

Further, the coating amount after drying of the resin intermediate layer in the present invention is preferably in the range of 0.1 to 5.0 g / m ² from the viewpoint of printing durability, image reproducibility, and sensitivity. More preferably, it is in the range of ^{2 to} 2.0 g / m ² , and still more preferably in the range of 0.5 to 1.5 g / m ² .

[Plate making of lithographic printing plate precursor]
The plate making process (image exposure, development process, printing process) in the lithographic printing plate precursor according to the invention will be described.

(exposure)
As the light source of the light beam used for image exposure, a light source having an emission wavelength in the near infrared to infrared region is preferable, and a solid laser or a semiconductor laser is particularly preferable.

(developing)
As the developer and replenisher used when developing the lithographic printing plate precursor according to the invention, conventionally known alkaline aqueous solutions can be used.
For example, sodium silicate, potassium, tribasic sodium phosphate, potassium, ammonium, dibasic sodium phosphate, potassium, ammonium, sodium carbonate, potassium, ammonium, sodium bicarbonate, potassium, Examples include inorganic alkali salts such as ammonium, sodium borate, potassium, ammonium, sodium hydroxide, ammonium, potassium, and lithium. In addition, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, triisopropylamine, n-butylamine, monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, Organic alkali agents such as ethyleneimine, etherediamine, and pyridine are also used. These alkali agents are used alone or in combination of two or more.
Among these alkali agents, particularly preferred developers are aqueous silicate solutions such as sodium silicate and potassium silicate. The reason is that the developability can be adjusted by the ratio and concentration of silicon oxide SiO ₂ and alkali metal oxide M ₂ O, which are silicate components. For example, Japanese Patent Application Laid-Open No. 54-62004, Alkali metal silicates as described in JP-B-57-7427 are effectively used.

Further, when developing using an automatic developing machine, an aqueous solution (replenisher) having a higher alkali strength than that of the developer is added to the developer, so that a large amount of the developer can be obtained without replacing the developer in the developer tank for a long time. It is known that PS plates can be processed. This replenishment method is also preferably applied in the present invention. Various surfactants and organic solvents can be added to the developer and replenisher as necessary for the purpose of promoting and suppressing developability, dispersing development residue, and improving ink affinity of the printing plate image area.
Preferred surfactants include anionic, cationic, nonionic and amphoteric surfactants. If necessary, the developer and replenisher may contain reducing agents such as hydroquinone, resorcin, sulfurous acid, bisulfite, and other inorganic acids such as sodium salts and potassium salts, organic carboxylic acids, antifoaming agents, and hard water softeners. It can also be added.
The lithographic printing plate precursor developed by using the developer and the replenisher is post-treated with a desensitizing solution containing rinse water containing a washing water, a surfactant or the like, gum arabic or a starch derivative. These post-treatments can be used in various combinations as post-treatments when used as a lithographic printing plate precursor according to the present invention.

  In recent years, automatic developing machines for printing plates have been widely used in the plate making and printing industries in order to rationalize and standardize plate making operations. This automatic developing machine is generally composed of a developing unit and a post-processing unit, and includes an apparatus for transporting the printing plate, each processing liquid tank and a spray device, and each pumped up by a pump while transporting the exposed printing plate horizontally. The processing liquid is sprayed from the spray nozzle and developed. In addition, recently, a method is also known in which a printing plate is dipped and conveyed by a submerged guide roll or the like in a processing liquid tank filled with the processing liquid. In such automatic processing, each processing solution can be processed while being supplemented with a replenisher according to the processing amount, operating time, and the like. In addition, a so-called disposable processing method in which processing is performed with a substantially unused processing solution can also be applied.

  In the lithographic printing plate precursor according to the invention, image portions unnecessary for the lithographic printing plate obtained by image exposure, development, washing and / or rinsing and / or gumming (for example, film edge marks of the original film, etc.) ), Unnecessary image portions are erased. Such erasing is preferably performed by applying an erasing solution to an unnecessary image portion as described in Japanese Patent Publication No. 2-13298, and leaving it for a predetermined time, followed by washing with water. A method of developing after irradiating an unnecessary image portion with an actinic ray guided by an optical fiber as described in JP-A-59-174842 can also be used.

(Heat treatment (burning treatment))
The lithographic printing plate obtained as described above can be subjected to a printing process after applying a desensitized gum if desired. However, if it is desired to obtain a lithographic printing plate with a higher printing durability, it is desired. The burning process is performed. In particular, in the present invention, when a resin having a phenolic hydroxyl group is used as the alkali-soluble resin (A), the phenolic hydroxyl group has thermal crosslinkability. The property is significantly improved.

Prior to the burning treatment, the surface is treated with a surface conditioning solution as described in JP-B-61-2518, JP-A-55-28062, JP-A-62-21859, and JP-A-61-159655. It is preferable. As its method, with a sponge or absorbent cotton soaked with the surface-adjusting liquid, it is applied onto a lithographic printing plate, or a method in which the printing plate is immersed and applied in a vat filled with the surface-adjusting liquid, Application by an automatic coater is applied. Further, it is more preferable to make the coating amount uniform with a squeegee or a squeegee roller after coating.
In general, the amount of surface-adjusting solution applied is suitably 0.03 to 0.8 g / m ² (dry mass). Thereafter, the lithographic printing plate coated with the leveling liquid may be dried as necessary.

Subsequently, the lithographic printing plate of the present invention is subjected to a heat treatment. The heat treatment method is not particularly limited as long as it can exhibit the effect of improving the burning printing durability, which is one of the effects of the present invention, by applying heat to the plate surface. The method of heating is mentioned.
In the present invention, among the above heating methods, a method of heating to a high temperature with a burning processor (for example, a burning processor sold by Fuji Photo Film Co., Ltd .: “BP-1300”) or the like is preferable. The heating temperature and heating time in this case depend on the type of components constituting the recording layer, but are preferably in the range of 0.5 to 20 minutes in the range of 150 to 300 ° C, and 1 to 1 in the range of 180 to 270 ° C. A range of 10 minutes is more preferred.

The lithographic printing plate that has been burned can be subjected to conventional treatments such as washing and gumming as needed, but a surface-conditioning solution containing a water-soluble polymer compound is used. In such a case, a so-called desensitizing treatment such as gumming can be omitted.
The lithographic printing plate obtained by such processing is applied to an offset printing machine or the like and used for printing a large number of sheets.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

(Production of support)
Supports A, B, C, and D were prepared by using a JIS-A-1050 aluminum plate having a thickness of 0.3 mm in combination with the following processes.

(A) Mechanical roughening treatment The machine is rotated by a roller-type nylon brush while supplying a suspension of polishing simultaneous J (silica sand) having a specific gravity of 1.12 and water as a polishing slurry to the surface of the aluminum plate. Roughening was performed. The average particle size of the abrasive was 8 μm, and the maximum particle size was 50 μm. The material of the nylon bran was 6 · 10 nylon, the hair length was 50 mm, and the hair diameter was 0.3 mm. The nylon brush was planted so as to be dense by making a hole in a stainless steel tube having a diameter of 300 mm. Three rotating brans were used. The distance between the two support rollers (φ200 mm) at the bottom of the bran was 300 mm. The brush roller was pressed until the load of the drive motor for rotating the brush became 7 kW plus with respect to the load before the brush roller was pressed against the aluminum plate. The rotating direction of the brush was the same as the moving direction of the aluminum plate. The rotation speed of the brush was 200 rpm.

(B) Alkali etching treatment The aluminum plate obtained above was sprayed with an aqueous NaOH solution at a temperature of 70 ° C. (concentration 26 mass%, aluminum ion concentration 6.5 mass%) to carry out an etching treatment, and the aluminum plate was 6 g / m. ² dissolved. Thereafter, washing with water was performed using well water.

(C) Desmutting treatment Desmutting treatment was performed by spraying with a 1% by weight aqueous solution of nitric acid at a temperature of 30 ° C. (containing 0.5% by weight of aluminum ions), and then washed with water by spraying. The nitric acid aqueous solution used for the desmut was the waste liquid from the step of electrochemical surface roughening using alternating current in nitric acid aqueous solution.

(D) Electrochemical roughening treatment An electrochemical roughening treatment was carried out continuously using an alternating voltage of 60 Hz. The electrolytic solution at this time was a nitric acid 10.5 g / liter aqueous solution (aluminum ion 5 g / liter) at a temperature of 50 ° C. The AC power supply waveform has an electrochemical surface roughening treatment using a carbon electrode as a counter electrode using a trapezoidal rectangular wave alternating current with a time TP of 0.8 msec until the current value reaches a peak from zero, a DUTY ratio of 1: 1. went. Ferrite was used for the auxiliary anode. The electrolytic cell used was a radial cell type.
The current density was 30 A / dm ² at the peak current value, and the amount of electricity was 220 C / dm ² in terms of the total amount of electricity when the aluminum plate was the anode. 5% of the current flowing from the power source was shunted to the auxiliary anode.
Thereafter, washing with water was performed using well water.

(E) Alkali etching treatment The aluminum plate was sprayed at a caustic soda concentration of 26% by mass and an aluminum ion concentration of 6.5% by mass at 32 ° C. to dissolve the aluminum plate by 0.20 g / m ² , The smut component mainly composed of aluminum hydroxide generated when electrochemical surface roughening was used was removed, and the edge portion of the generated pit was melted to smooth the edge portion. Thereafter, washing with water was performed using well water.

(F) Desmut treatment Desmut treatment was performed by spraying with a 15% by weight aqueous solution of nitric acid at a temperature of 30 ° C. (containing 4.5% by weight of aluminum ions), and then washed with water using well water. The nitric acid aqueous solution used for the desmut was the waste liquid from the step of electrochemical surface roughening using alternating current in nitric acid aqueous solution.

(G) Electrochemical surface roughening treatment An electrochemical surface roughening treatment was performed continuously using an alternating voltage of 60 Hz. The electrolytic solution at this time was a hydrochloric acid 7.5 g / liter aqueous solution (containing 5 g / liter of aluminum ions) at a temperature of 35 ° C. The AC power supply waveform was a rectangular wave, and an electrochemical surface roughening treatment was performed using a carbon electrode as a counter electrode. Ferrite was used for the auxiliary anode. The electrolytic cell used was a radial cell type.
The current density was 25 A / dm ² at the peak current value, and the amount of electricity was 50 C / dm ² in terms of the total amount of electricity when the aluminum plate was the anode.
Thereafter, washing with water was performed using well water.

(H) Alkali etching treatment The aluminum plate was sprayed at a caustic soda concentration of 26% by mass and an aluminum ion concentration of 6.5% by mass at 32 ° C. to dissolve the aluminum plate at 0.10 g / m ² , The smut component mainly composed of aluminum hydroxide generated during the electrochemical surface roughening treatment was removed, and the edge portion of the generated pit was dissolved to smooth the edge portion. Thereafter, washing with water was performed using well water.

(I) Desmut treatment A desmut treatment by spraying was performed with a 25% by mass aqueous solution of sulfuric acid having a temperature of 60 ° C. (containing 0.5% by mass of aluminum ions), and then water washing by spraying was performed using well water.

(J) Anodizing treatment As the electrolytic solution, sulfuric acid was used. The electrolyte solutions all had a sulfuric acid concentration of 170 g / liter (containing 0.5 mass% of aluminum ions), and the temperature was 43 ° C. Thereafter, washing with water was performed using well water.
Both current densities were about 30 A / dm ² . The final oxide film amount was 2.7 g / m ² .

<Support A>
The steps (a) to (j) were performed in order, and the support was prepared so that the etching amount in the step (e) was 3.4 g / m ² .
<Support B>
Except for omitting the steps (g), (h) and (i) among the above steps, each step was performed in order to prepare a support.
<Support C>
A support was prepared by sequentially performing each step except that the steps (a), (g), (h), and (i) were omitted.
<Support D>
Except for omitting the process of the above step (a) and (d) (e) (f ) performs the steps in turn, supported as total amount of electricity is 450C / dm ² in step (g) The body was made.
Supports A, B, C, and D obtained as described above were subsequently subjected to the following hydrophilization treatment (alkali metal silicate treatment) and undercoating treatment.

(K) Alkali metal silicate treatment Alkali metal silica was obtained by immersing the aluminum support obtained by anodizing treatment in a treatment layer of a 1 mass% aqueous solution of sodium silicate No. 3 at a temperature of 30 ° C for 10 seconds. Acid salt treatment (silicate treatment) was performed. Then, the water washing by the spray using well water was performed. The amount of silicate adhering at that time was 3.6 mg / m ² .

(Undercoating)
On the aluminum support after the alkali metal silicate treatment obtained as described above, an undercoat solution having the following composition was applied and dried at 80 ° C. for 15 seconds. The coating amount after drying was 16 mg / m ² .

<Undercoat liquid composition>
・ The following polymer compound 0.3g
・ Methanol 100g
・ Water 1.0g

[Examples 1-7, Comparative Examples 1-2]
A coating solution for a lower layer having the following composition was coated on the obtained support A with a wire bar, and then dried in a drying oven at 150 ° C. for 60 seconds to obtain a coating amount of 0.95 g / m ² .
On the obtained lower layer, the upper layer use cloth liquid of the following composition was apply | coated with the wire bar. After coating, drying was performed at 130 ° C. for 90 seconds in a drying oven, and positive lithographic printing plate precursors of Examples 1 to 7 and Comparative Examples 1 and 2 were prepared with a total coating amount of 1.25 g / m ² .

<Coating liquid for lower layer>
-Copolymer 1 (synthesized by the following) 1.833 g
・ Cyanine dye A (the following structure) 0.098g
・ 2-Mercapto-5-methylthio-
1,3,4-thiadiazil 0.030g
. Cis-Δ ⁴ -tetrahydrophthalic anhydride 0.100 g
・ 4,4'-sulfonyldiphenol 0.090g
・ 0.008 g of p-toluenesulfonic acid
・ The counter anion of ethyl violet is changed to 6-hydroxynaphthalenesulfonic acid 0.100 g
・ 3-Methoxy-4-diazodiphenylamine
Hexafluorophosphenate 0.030g
・ Fluorosurfactant 0.035g
(Megafuck F-780, manufactured by Dainippon Ink & Chemicals, Inc.)
・ Methyl ethyl ketone 26.6g
1-methoxy-2-propanol 13.6 g
・ Γ-Butyrolactone 13.8g

<Synthesis of Copolymer 1>
A 500 ml three-necked flask equipped with a stirrer, a condenser tube and a dropping funnel is charged with 31.0 g (0.36 mol) of methacrylic acid, 39.1 g (0.36 mol) of chlorogysanethyl and 200 ml of acetonitrile and cooled in an ice water bath. The mixture was stirred while. To this mixture, 36.4 g (0.36 mol) of triethylamine was dropped with a dropping funnel over about 1 hour. After completion of the dropwise addition, the ice-water bath was removed, and the mixture was stirred at room temperature for 30 minutes.
To this reaction mixture, 51.7 g (0.30 mol) of p-aminobenzesisulfonamide was added, and the mixture was stirred for 1 hour while warming to 70 ° C. in an oil bath. After completion of the reaction, the mixture was added to 1 liter of water with stirring, and the resulting mixture was stirred for 30 minutes. The mixture was filtered to take out a precipitate, which was slurried with 500 ml of water, and then the slurry was filtered, and the obtained solid was dried to dry a white solid of N- (p-aminosulfonylphenyl) methacrylamide. Was obtained (yield 46.9 g).

  Next, 4.61 g (0.0192 mol) of N- (p-aminosulfonylphenyl) methacrylamide and 2.58 g of ethyl methacrylate (0.0258 mol) were added to a 20 ml three-necked flask equipped with a stirrer, a condenser and a dropping funnel. ), 0.80 g (0.015 mol) of acrylonitrile and 20 g of N, N-dimethylacetamide were added, and the mixture was stirred while heating to 65 ° C. with a hot water bath. To this mixture, 0.12 g of 2,2′-azobis (2,4-dimethylvaleronitrile) (trade name: “V-65”, manufactured by Wako Pure Chemical Industries, Ltd.) was added as a polymerization initiator, and the mixture was heated to 65 ° C. While maintaining, the mixture was stirred for 2 hours under a nitrogen stream. This reaction mixture was further mixed with 4.61 g of N- (p-aminosulfonylphenyl) methacrylamide, 2.58 g of methyl methacrylate, 0.80 g of acrylonitrile, 20 g of N, N-dimethylacetamide and 0.15 g of “V-65”. Was dropped by a dropping funnel over 2 hours. After completion of the dropwise addition, the resulting mixture was further stirred at 65 ° C. for 2 hours. After completion of the reaction, 40 g of methanol was added to the mixture, cooled, and the resulting mixture was added to 2 liters of water while stirring the water. After stirring the mixture for 30 minutes, the precipitate was removed by filtration and dried. 15 g of a white solid was obtained. It was 54,000 when the weight average molecular weight (polystyrene standard) of this specific copolymer 1 was measured by the gel permeation chromatography.

<Upper layer coating solution>
・ With ethyl methacrylate and 2-methacryloyloxyethyl succinic acid
Copolymer of 0.040 g
(Molar ratio 75:25, weight average molecular weight 70,000)
・ Phenol Cresol-Formaldehyde Novolak 0.400g
(Phenol: m-cresol: p-cresol = 50: 10: 40 (molar ratio),
Weight average molecular weight: 5,000)
・ Specific sulfonium salt or comparative sulfonium salt 0.3g
・ Cyanine dye A (the above structure) 0.015 g
-Ethyl violet counter anion changed to 6-hydroquinnaphthalene sulfonic acid 0.012g
・ Fluorine surfactant 0.022g
(Megafuck F-780, manufactured by Dainippon Ink & Chemicals, Inc.)
・ Methyl ethyl ketone 13.1g
1-methoxy-2-propanol 6.79g

  In addition, the number of the cation part and anion part which show the structure of the specific sulfonium salt of following Table 1 represents the number attached | subjected to the cation part and the anion part of the said specific example. Moreover, the structures of the comparative sulfonium salts 1 and 2 used in the comparative examples are as shown below.

[Evaluation of lithographic printing plate precursor]
The evaluation of the lithographic printing plate precursor was performed for each of the development latitude and scratch resistance items. Details of the evaluation method are as follows.
1. Development Latitude The lithographic printing plate precursor obtained as described above is stored for 5 days under the conditions of a temperature of 25 ° C. and a relative humidity of 50%, and then a Trendsetter 3244VX manufactured by Creo at a beam intensity of 12.0 W and a drum rotation speed of 50 rpm. A test pattern was drawn in an image.
Thereafter, a PS processor 900H manufactured by Fuji Photo Film Co., Ltd. was used, in which the electric conductivity was changed by changing the dilution ratio by changing the mass ratio of water in the alkaline developer of the following A composition and B composition. The liquid temperature was kept at 30 ° C., and development was performed with a development time of 40 seconds. At this time, the developer having the highest conductivity and the lowest conductivity of the developer in which the image portion was not eluted and the development was successfully performed without contamination and coloring caused by the poorly developed photosensitive layer residual film. The difference was evaluated as development latitude.

<Alkali developer A composition>
・ SiO ₂ · K ₂ O (K ₂ O / SiO ₂ = 1/1 (molar ratio)) 4.0% by mass
・ Citric acid 0.5% by mass
・ Polyethylene glycol lauryl ether 0.5% by mass
(Weight average molecular weight 1,000)
・ Water 95.0 mass%

<Alkali developer B composition>
・ D sorbit 2.5% by mass
-Sodium hydroxide 0.85 mass%
・ Polyethylene glycol lauryl ether 0.5% by mass
(Weight average molecular weight 1,000)
・ Water 96.15% by mass

2. Evaluation of scratch resistance The surface of the lithographic printing plate precursor obtained as described above was scratched by applying a load to a sapphire needle (tip diameter: 1.0 mm) with a scratch tester manufactured by HEIDON. Thereafter, the image was exposed imagewise with a Trend setter 3244 manufactured by Creo at a beam intensity of 9.0 W and a drum rotation speed of 150 rpm. Fuji Photo Film was developed with Fuji Photo Film Co., Ltd. developer DT-2 (diluted 1: 8) and Fuji Photo Film Co., Ltd. Fischer FG-1 (diluted 1: 1). Using a PS processor LP940H manufactured by Film Co., Ltd., the liquid temperature was kept at 30 ° C., and development was performed for 12 s. The electric conductivity of the developer at this time was 43 mS / cm.
The developed lithographic printing plate was visually observed, and the maximum load amount (g) without scratches was defined as a scratch resistance value. The larger the value, the better the scratch resistance. The results are shown in the table below.

<Evaluation of planographic printing plate precursors of Examples 1 to 7 and Comparative Examples 1 and 2>
The lithographic printing plate precursors of Examples 1 to 7 and Comparative Examples 1 and 2 were evaluated for development latitude and scratch resistance by the above methods. Developer B was used as the developer. The results are shown in Table 1 below.

As shown in Table 1, it can be seen that the lithographic printing plate precursors of Examples 1 to 7 achieve improved development latitude and improved scratch resistance.
On the other hand, it can be seen that Comparative Examples 1 and 2 using comparative sulfonium salts 1 and 2 outside the scope of the present invention are inferior in both development latitude and scratch resistance compared to Examples 1 to 7. In particular, in Comparative Example 1 using the comparative sulfonium salt 1 bonded to an aromatic hydrocarbon in a state in which the hydroxyl group is not protected, both development latitude and scratch resistance are compared with those in Examples 1-7. It is understood that is greatly inferior.

(Example 8-12 and Comparative Example 3-4)
A coating solution for a lower layer having the following composition was applied to the obtained support C with a wire bar, and then dried in a drying oven at 120 ° C. for 90 seconds to obtain a coating amount of 0.60 g / m ² .
On the obtained lower layer, the upper layer coating solution having the following composition was applied with a wire bar. After coating, drying was performed at 120 ° C. for 90 seconds in a drying oven to prepare positive lithographic printing plate precursors of Examples 8 to 12 and Comparative Examples 3 to 4 with a total coating amount of 1.35 g / m ² .

<Lower layer cloth>
-Said copolymer 1 2.200g
・ Cyanine dye A (the above structure) 0.098 g
・ 2-Mercapto-5-methylthio
-1,3,4-thiadiazole 0.030 g
. Cis-Δ ⁴ -tetrahydrophthalic anhydride 0.100 g
・ 4,4'-sulfonyldiphenol 0.090g
・ 0.008 g of p-toluenesulfonic acid
-The counter anion of ethyl violet is changed to 6-hydroquinnaphthalenesulfonic acid 0.100 g
・ 3-Methoxy-4-diazodiphenylamine
Hexafluorophosphate 0.030g
・ Fluorosurfactant 0.035g
(Megafuck F-780, manufactured by Dainippon Ink & Chemicals, Inc.)
・ Methyl ethyl ketone 26.6g
1-methoxy-2-propanol 13.6 g
・ Dimethylsulfoxide 13.8g

<Upper layer coating solution>
・ With ethyl methacrylate and 2-methacryloyloxyethyl succinic acid
Copolymer of 0.040 g
(Molar ratio 70:30, weight average molecular weight 88,000)
・ Phenol Cresol-Formaldehyde Novolak 0.250g
(Phenol: m-cresol: p-cresol = 60: 5: 35 (molar ratio))
Weight average molecular weight: 5,500)
・ Specific sulfonium salt or comparative sulfonium salt 0.04g
・ Cyanine dye A (the above structure) 0.015 g
・ Fluorine surfactant 0.022g
(Megafuck F-780, manufactured by Dainippon Ink & Chemicals, Inc.)
・ Methyl ethyl ketone 13.1g
1-methoxy-2-propanol 6.79g

<Evaluation of Examples 8 to 12 and Comparative Examples 3 to 4>
The obtained planographic printing plate precursors of Examples 8 to 12 and Comparative Examples 3 to 4 were evaluated in the same manner as in Example 1. Developer B was used as the developer. The results are shown in Table 2 below.
In addition, the number of the cation part and anion part which show the structure of the specific sulfonium salt of the following Table 2 represents the number attached | subjected to the cation part and the anion part of the said specific example.

As shown in Table 2, it can be seen that the lithographic printing plate precursors of Examples 8 to 12 achieve improved development latitude and improved scratch resistance as compared with Comparative Examples 3 and 4.

(Examples 15 to 21, Comparative Examples 5 to 6)
A coating solution for a lower layer having the following composition was applied to the obtained support D with a wire bar, and then dried in a drying oven at 150 ° C. for 60 seconds to obtain a coating amount of 0.81 g / m ² .
On the obtained lower layer, the upper layer coating solution having the following composition was applied with a wire bar. After coating, drying was performed at 120 ° C. for 90 seconds in a drying oven, and positive lithographic printing plate precursors of Examples 15 to 21 and Comparative Examples 5 to 6 were prepared with a total coating amount of 1.1 g / m ² .

<Coating liquid for lower layer>
-Copolymer 1 2.133 g
・ Cyanine dye A (the above structure) 0.098 g
. Cis-Δ ⁴ -tetrahydrophthalic anhydride 0.110 g
・ 4,4'-sulfonyldiphenol 0.090g
・ 0.008 g of p-toluenesulfonic acid
・ The counter anion of ethyl violet is changed to 6-hydroxynaphthalenesulfonic acid 0.100 g
・ 3-Methoxy-4-diazodiphenylamine
Hexafluorophosphate 0.030g
・ Fluorosurfactant 0.035g
(Megafuck F-780, manufactured by Dainippon Ink & Chemicals, Inc.)
・ Methyl ethyl ketone 26.6g
1-methoxy-2-propanol 13.6 g
・ Γ-Butyrolactone 13.8g

<Upper layer coating solution>
・ With ethyl methacrylate and 2-methacryloyloxyethyl succinic acid
Copolymer of 0.035g
(Molar ratio 65:35, weight average molecular weight 78,000)
・ Cresol-formaldehyde noborasok 0.300g
(M-cresol: p-cresol = 60: 40, weight average molecular weight: 4,100)
-Specific sulfonium salt or comparative sulfonium salt 0.020 g
・ Cyanine dye A (the above structure) 0.015 g
・ Fluorine surfactant 0.022g
(Megafuck F-780, manufactured by Dainippon Ink & Chemicals, Inc.)
・ Methyl ethyl ketone 13.1g
1-methoxy-2-propanol 6.79g

<Evaluation of Examples 15 to 21 and Comparative Examples 5 to 6>
The obtained lithographic printing plate precursor was evaluated by the method described above. Developer A was used as the developer. The following results are shown in Table 3.
The numbers of the cation part and the anion part showing the structure of the specific sulfonium salt described in Table 3 below are the numbers given to the cation part and the anion part of the specific examples.

  As shown in Table 3, it can be seen that the lithographic printing plate precursors of Examples 15 to 21 achieve improved development latitude and improved scratch resistance as compared with Comparative Examples 5 to 6.

(Examples 23 to 27 , Comparative Examples 7 to 8)
The following recording layer coating solution was applied to the obtained support D and dried at 120 ° C. for 90 seconds to form a recording layer having a single layer structure, and lithographic printing of Examples 23 to 27 and Comparative Examples 7 to 8 I got the original version. The coating amount after drying was 1.60 g / m ² .

<Recording layer coating solution>
・ Phenol Cresol-Formaldehyde Novolak 1.0g
(Phenol: m-cresol: p-cresol = 50: 20: 30 (molar ratio),
(Weight average molecular weight: 4,500)
・ Specific sulfonium salt or comparative sulfonium salt 0.08g
・ Cyanine dye A (the above structure) 0.05 g
・ Counter anion of Victoria Pure Blue BOH
1-naphthalene sulfonate anion 0.01g
・ Fluorosurfactant 0.05g
(Megafuck F-177, manufactured by Dainippon Ink & Chemicals, Inc.)
・ Methyl ethyl ketone 9.0g
・ 9.0 g of 1-methoxy-2-propanol

<Evaluation of Examples 23 to 27 and Comparative Examples 7 to 8>
The obtained lithographic printing plate precursors of Examples 23 to 27 and Comparative Examples 7 to 8 were evaluated in the same manner as in Example 1. Developer A was used as the developer. The results are shown in Table 4.
The numbers of the cation part and the anion part showing the structure of the specific sulfonium salt described in Table 4 below represent the numbers given to the cation part and the anion part of the specific examples.

As shown in Table 4, it can be seen that the lithographic printing plate precursors of Examples 23 to 27 achieve improved development latitude and improved scratch resistance as compared with Comparative Examples 7 to 8.
Further, in comparison between Examples 1 to 21 and Examples 23 to 27 , it was confirmed that the lithographic printing plate precursor according to the present invention exhibited excellent effects in the same manner as in the case of the multi-layer even when the recording layer was a single layer. It was done.

Claims (1)

On a support having a hydrophilic surface, (A) a water-insoluble and alkali-soluble resin, (B) an infrared absorber, and (C) a sulfonium salt represented by the following general formula (1), A positive lithographic printing plate precursor for infrared lasers, comprising a recording layer whose solubility in an alkaline aqueous solution increases upon exposure.

[In the general formula (1), R ₁ and R ₂ each independently be TABLE an alkyl group, a cycloalkyl group, an aralkyl group, or an aryl group. Ar is an —O—R group that is converted to a hydroxyl group by decomposing by the action of an acid or heat (wherein R represents a protecting group, and —CO ₂ — is not included as a linking group forming the protecting group) . ), and an aromatic having at least one substituent -COO-R 'groups (where R' to convert it to decompose by the action of an acid or heat to the carboxyl group is selected from representative.) the protecting group Represents a group hydrocarbon group. X ^- is to display the residue derived from a compound having a pKa of less than 5. R ₁ and R ₂ may be bonded to each other to form a cyclic structure. ]