JP2010237435A - Lithographic printing plate precursor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an infrared-sensitive positive-working photosensitive lithographic printing plate precursor that is superior in both of chemical resistance in an image area and developability. <P>SOLUTION: The positive-working photosensitive lithographic printing plate precursor has, on a support having a hydrophilic surface, a recording layer comprising an alkali-soluble or alkali-swellable polymer having a structural unit represented by general formula (1), a novolac resin, an infrared absorber, and at least one member selected from aromatic group-containing sulfonium salts and iodonium salts. In general formula (1), R<SP>1</SP>represents a hydrogen atom or methyl group, X represents a single bond, -COO-, or -CONH-, Ar<SP>1</SP>and Ar<SP>2</SP>each represent an optionally substituted aromatic group or heteroaromatic group, and Y represents -SO<SB>2</SB>NH- or -NHSO<SB>2</SB>-. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

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

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 region have been increasing in output and size. Therefore, these lasers are very useful as an exposure light source when making a plate directly from digital data such as a computer.
A photosensitive lithographic printing plate precursor for infrared laser, which uses an infrared laser having a light emitting region in the infrared region as an exposure light source, is a lithographic plate comprising a binder resin and an IR dye that absorbs light and generates heat as essential components. It is a printing plate master. When the infrared laser is exposed to the infrared laser on the lithographic printing plate precursor, the IR dye or the like in the lithographic printing plate precursor for the infrared laser is added to the binder resin in the unexposed portion (image portion) when a positive photosensitive layer is provided. It acts as a dissolution inhibitor that substantially lowers the solubility of the binder resin by interacting with it. On the other hand, in the exposed portion (non-image portion), the IR dye or the like absorbs light and generates heat, so that the interaction between the IR dye or the like and the binder resin is weakened. Therefore, at the time of development, the exposed portion (non-image portion) is dissolved in an alkaline developer, and a lithographic printing plate is formed.

Such lithographic printing plate precursors for infrared lasers still have various problems, and one of them is compatibility between developability and chemical resistance. In other words, in the positive type where the exposed part is developed, if the solubility in the developer is improved, the developer in the unexposed part and various chemical resistances deteriorate, so how to make the two compatible? It is a point.
Various studies have been made on these issues. For example, polyvinyl acetal is used (for example, refer to Patent Document 1), or the resin layer structure of the lithographic printing plate is made into two or more layers, for example, a polymer compound containing a maleimide compound as a lower layer is used ( For example, see Patent Document 2), and further, the use of a copolymer having a specific functional group (see, for example, Patent Document 3) has been proposed. That level up was desired.

US Patent Application Publication No. 2004/0020484 US Patent Application Publication No. 2004/0067432 European Patent Application No. 1826001

  It is an object of the present invention to provide an infrared sensitive positive photosensitive lithographic printing plate precursor, particularly a positive photosensitive lithographic printing plate precursor for infrared laser, which is excellent in both chemical resistance and developability of an image area. is there. Another object of the present invention is to provide a photosensitive lithographic printing plate precursor for infrared laser, which is excellent in development latitude, and can significantly improve printing durability when heated at a high temperature after development. That is.

As a result of intensive studies, the present inventor has found that the above-mentioned problems can be achieved by the following photosensitive lithographic printing plate precursor for infrared laser.
That is, the present invention has an alkali-soluble or swellable polymer having a structural unit represented by the following general formula (1), a novolak resin, an infrared absorber, and an aromatic group on a support having a hydrophilic surface. A positive photosensitive lithographic printing plate precursor provided with a recording layer containing at least one selected from a sulfonium salt and an iodonium salt. In the present invention, the recording layer of the positive photosensitive lithographic printing plate precursor can be composed of a plurality of layers. Accordingly, the present invention also provides a recording layer containing an alkali-soluble or swellable polymer having a structural unit represented by the following general formula (1) on a support having a hydrophilic surface, and further a novolac on the recording layer. The present invention is directed to a positive photosensitive lithographic printing plate precursor provided with a recording layer containing at least one selected from resins, infrared absorbers, and sulfonium salts and iodonium salts having an aromatic group.

…（１）

式中、Ｒ¹は水素原子もしくはメチル基を表す。
Ｘは単結合、−ＣＯＯ−、−ＣＯＮＨ−を表す。
Ａｒ¹、Ａｒ²は、それぞれ、置換基を有してもよい芳香族基、又は芳香族を構成する炭素原子のうちの１つないし２つが、Ｎ，Ｏ、Ｓのうちいずれかの原子で置換された複素芳香族基を表す。Ｙは−ＳＯ₂ＮＨ−、−ＮＨＳＯ₂−を表す。

... (1)

In the formula, R ¹ represents a hydrogen atom or a methyl group.
X represents a single bond, —COO— or —CONH—.
Ar ¹ and Ar ² are each an aromatic group which may have a substituent, or one or two of carbon atoms constituting the aromatic group is any one of N, O and S atoms. Represents a substituted heteroaromatic group. Y represents —SO ₂ NH— or —NHSO ₂ —.

According to the present invention, it is possible to provide a photosensitive lithographic printing plate precursor for an infrared laser which is excellent in both chemical resistance and developability of an image area. This photosensitive lithographic printing plate precursor for infrared laser has excellent development latitude, and when it is heat-treated at a high temperature after development, the printing durability can be remarkably improved.
The mechanism that can achieve both good chemical resistance in the image area and good developability in plate making by the configuration of the present invention is considered as follows. That is, the specific polymer, novolak resin, sulfonium salt or iodonium salt having an aromatic group all interact with each other because they have a conjugated system such as an aromatic group, and the chemical resistance and resistance of the image area. The developer suitability can be improved more than the properties of individual compounds. Further, the sulfonium salt or iodonium salt is decomposed by heat, and the interaction disappears. Therefore, the developability of the entire exposed portion is improved, and as a result, the development latitude is considered to be improved.

Hereinafter, each component of the lithographic printing plate precursor according to the invention will be sequentially described.
[Recording layer]
The recording layer of the lithographic printing plate precursor according to the invention may be composed of a single layer (single layer) or a plurality of layers (multilayer). When the recording layer is a plurality of layers, it is preferably composed of two layers. The alkali-soluble or swellable polymer having the structural unit represented by the general formula (1) used in the present invention is hereinafter also referred to as a specific polymer.
<Specific polymer>
The specific polymer is a polymer having a structural unit represented by the following general formula (1). More specifically, the specific polymer is a polymer having a structural unit represented by the following general formula (1) as a copolymerization component.

…（１）

上記一般式（１）中、Ｒ¹は水素原子又はメチル基を表す。Ｘは単結合、−ＣＯＯ−、−ＣＯＮＨ−を表すが、好ましくは−ＣＯＯ−、−ＣＯＮＨ−である。Ａｒ¹、Ａｒ²は、それぞれ置換基を有してもよい芳香族基を表すか、又は芳香族を構成する炭素原子のうちの１つないし２つが、Ｎ，Ｏ、Ｓのうちいずれかの原子で置換された複素芳香族基を表す。Ａｒ¹は、５員環または６員環であることが好ましく、更に好ましくは６員環である。Ａｒ²は、５員環または６員環であることが好ましい。この中で、Ａｒ¹、Ａｒ²のうち、少なくとも一方が複素芳香族環であることが好ましい。
上記構造単位の具体例として、Ａｒ¹が芳香族環を表し、Ａｒ²が芳香族を構成する炭素原子のうちの１つないし２つが、Ｎ，Ｏ、Ｓのうちいずれかの原子で置換された複素芳香族環である、構造単位が挙げられる。
Ａｒ¹、Ａｒ²の芳香族基あるいは複素芳香族基上の好ましい置換基は、炭素数１〜４のアルキル基、又は炭素数１〜４のアルコキシル基である。

... (1)

In the general formula (1), R ¹ represents a hydrogen atom or a methyl group. X represents a single bond, —COO— or —CONH—, preferably —COO— or —CONH—. Ar ¹ and Ar ² each represent an aromatic group which may have a substituent, or one or two of carbon atoms constituting the aromatic group are any of N, O and S Represents a heteroaromatic group substituted with an atom. Ar ¹ is preferably a 5-membered or 6-membered ring, more preferably a 6-membered ring. Ar ² is preferably a 5-membered ring or a 6-membered ring. Of these, at least one of Ar ¹ and Ar ² is preferably a heteroaromatic ring.
As a specific example of the structural unit, Ar ¹ represents an aromatic ring, and Ar ² is substituted with one or two of carbon atoms constituting the aromatic group by any one of N, O, and S atoms. And a structural unit which is a heteroaromatic ring.
A preferred substituent on the aromatic group or heteroaromatic group of Ar ¹ or Ar ² is an alkyl group having 1 to 4 carbon atoms or an alkoxyl group having 1 to 4 carbon atoms.

The aromatic group and heteroaromatic group represented by Ar ¹ and Ar ² may be selected from hydrocarbon aromatic rings such as benzene, naphthalene, and anthracene, and examples thereof include furan, thiophene, pyrrole, and imidazole. 1,2,3-triazole, 1,2,4-triazole, tetrazole, oxazole, isoxazole, thiazole, isothiazole, thiadiazole, oxadiazole, pyridine, pyridazine, pyrimidine, pyrazine, 1,3,5-triazine , 1,2,4-triazine, 1,2,3-triazine, and other heteroaromatic rings.
Further, the above-mentioned plurality of rings are condensed to take a condensed ring form such as benzofuran, benzothiophene, indole, indazole, benzoxazole, quinoline, quinazoline, benzimidazole, or benzotriazole. Also good.

Examples of monomers that can form the structural unit represented by the following general formula (1) are shown below, but the present invention is not limited to these.

The specific polymer is an alkali-soluble or swellable polymer having a structural unit represented by the general formula (1) as a copolymerization component, and is represented by the general formula (1) contained in the specific polymer. Only one type of structural unit may be used, or two or more types may be used in combination.
20-90 mol% is suitable for content of the structural unit represented by General formula (1) in a specific polymer, 30-80 mol% is preferable, More preferably, it is 30-70 mol%.
Other structural units in the specific polymer include a hydrophobic monomer having a substituent such as an alkyl group or an aryl group in the side chain structure of the monomer, an acidic group, an amide group, a hydroxy group or a side chain structure of the monomer. Examples thereof include hydrophilic monomers having an ethylene oxide group and the like, and these monomers can be appropriately selected according to the purpose. The selection of the monomer species to be copolymerized with the monomer species that derives the structural unit of the general formula (1) needs to be made within a range that does not impair the alkali solubility of the specific polymer.

In the specific polymer used in the present invention, examples of the other comonomer other than the monomer for deriving the structural unit represented by the general formula (1) include polymerizable compounds containing an acidic group. Examples of such an acidic group include the following (1) to (6).
(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) Carboxylic acid group (—CO ₂ H)
(5) Sulfonic acid group (—SO ₃ H)
(6) Phosphate group (—OPO ₃ H ₂ )
In the above (1) to (6), Ar represents a divalent aryl linking group which may have a substituent, and R represents a hydrocarbon group which may have a substituent.

Examples of the polymerizable compound having an acidic group selected from the above (1) to (6) include the following.
(1) Compounds having a phenol group in the side chain, such as acrylamide, methacrylamide, acrylic ester or methacrylic ester having a phenol group, or hydroxystyrene.

(2) A compound having a sulfonamide group, for example, a compound 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 these, low molecular weight 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 formulas (i) to (v ).

(In the formula, X ¹ and X ² each independently represent —O— or —NR ^7. R ¹ and R ⁴ each independently represent a hydrogen atom or —CH _3. R ² , R ⁵ , R ⁹ , R ¹² and R ¹⁶ each independently represents an alkylene group, a cycloalkylene group, an arylene group or an aralkylene group having 1 to 12 carbon atoms, and R ³ , R ⁷ and R ¹³ each independently represent Represents a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group, an aryl group or an aralkyl group, and R ⁶ and R ¹⁷ each independently represents an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group or an aryl group. R ⁸ , R ¹⁰ and R ¹⁴ each independently represents a hydrogen atom or —CH ₃ , R ¹¹ and R ¹⁵ each independently represent a single bond or an alkylene group having 1 to 12 carbon atoms. Cycloalkylene group, arylene group or Y ¹ and Y ² each independently represents a single bond or CO. The alkylene group, cycloalkylene group, arylene group, aralkylene group, alkyl group, cycloalkyl group, aryl group, or aralkyl group is It may have a substituent, and a preferred substituent is an alkyl group.)

  Among the compounds represented by formulas (i) to (v), in the lithographic printing plate precursor according to the invention, in particular, m-aminosulfonylphenyl methacrylate, N- (p-aminosulfonylphenyl) methacrylamide, N- ( p-Aminosulfonylphenyl) acrylamide and the like can be preferably used.

具体的には、Ｎ−（ｐ−トルエンスルホニル）メタクリルアミド、Ｎ−（ｐ−トルエンスルホニル）アクリルアミド等を好適に使用することができる。 (3) Examples of the compound having an active imide group include compounds each having one or more active imide groups represented by the following structural formula and one polymerizable unsaturated group in the molecule.

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

(4) Examples of the compound having a carboxylic acid group include compounds having at least one carboxylic acid group and polymerizable unsaturated group in the molecule, and in particular, acrylic acid, methacrylic acid, Maleic acid and itaconic acid can be preferably used.
(5) Examples of the compound having a sulfonic acid group include a compound having at least one sulfonic acid group and polymerizable unsaturated group in the molecule.
(6) Examples of the polymer compound having a phosphoric acid group include compounds having at least one phosphoric acid group and a polymerizable unsaturated group in the molecule.

  In addition to the above, there can be mentioned polymerizable unsaturated compounds having acidic groups (1) to (6) in the side chain and having a urea bond as a linking group. Among the polymerizable compounds having an acidic group of (1) to (6) described above, compounds having an acidic group of (1), (2), (4) are preferable, and the acidic compound of (2) is particularly preferable. Among the compounds having a group, those having a sulfonamide at the terminal.

  In the specific polymer, any polymerizable monomer may be further copolymerized. Other components are not particularly specified as long as they are monomers that can be copolymerized with the above-described monomer components, but (meth) acrylic acid esters, N-substituted (meth) acrylamides, acrylonitrile, styrenic compounds, maleimides, (Meth) acrylamide, N-substituted (meth) acrylamide, glycidyl (meth) acrylate, N-substituted maleimide, (meth) acrylic acid ester having a polyoxyethylene chain, 2-hydroxyethyl (meth) acrylate, vinylpyridine, N -Vinyl caprolactam and N-vinyl pyrrolidine can be mentioned.

  The weight average molecular weight (Mw) of the specific polymer is most preferably in the range of 5,000 to 1,000,000, preferably 7,000 to 500,000, particularly preferably 10,000 to 300,000. These molecular weights can be measured by gel permeation chromatography using N-methylpyrrolidone as a developing solvent. Monodispersed polystyrene can be used as a molecular weight standard substance in this case.

Examples of the structure of the specific polymer that can be suitably used in the present invention are shown below by combinations of the respective structural units. The numerical values are molar ratios.

As content of the specific polymer in a recording layer, it is preferable that it is 5 mass%-95 mass% in the total solid of a recording layer, and it is more preferable that it is 10 mass%-90 mass%.
In the lithographic printing plate precursor according to the invention, when the recording layer is a recording layer having a multilayer structure, the specific polymer is preferably contained in the lower recording layer located in the vicinity of the support. In this case, the content of the specific polymer in the lower recording layer is preferably 40% by mass to 95% by mass, and 50% by mass to 95% by mass in the total solid content of the lower recording layer. It is more preferable. The lower layer preferably contains no novolac resin.

<Novolac resin>
Novolac resins broaden the resins obtained by reaction of phenols with formaldehyde. Examples of phenols include phenol, o-cresol, m-cresol, p-cresol, 2,3-xylenol, 2,5-xylenol, 3,5-xylenol, resorcinol, pyrogallol, and bisphenol alone. You may mix and use two or more. Of these, phenol, o-cresol, m-cresol, p-cresol, and 2,3-xylenol are preferably used alone or in combination.
The novolak resin used in the present invention preferably has a weight average molecular weight of 500 to 20,000 and a number average molecular weight of 200 to 10,000 as measured by GPC method.
Specific examples are shown below.
(i) novolak resin comprising phenol / m-cresol / p-cresol = 50/30/20 (molar ratio), weight average molecular weight 8,000
(ii) novolak resin comprising m-cresol / p-cresol = 60/40 (molar ratio), weight average molecular weight 6,000
(iii) 2,3-xylenol / m-cresol / p-cresol = 10/40/50 (molar ratio) novolak resin, weight average molecular weight 5,000
(iv) novolak resin comprising 2,5-xylenol / phenol / m-cresol = 20/40/40 (molar ratio), weight average molecular weight 8,000

The content of the novolak resin in the recording layer is preferably 3% by mass to 50% by mass and more preferably 5% by mass to 40% by mass in the total solid content in the case of a single recording layer. preferable.
In the case where the recording layer is a recording layer having a multilayer structure, the novolak resin is preferably contained in the upper recording layer located near the surface (exposed surface). The content of the novolak resin in the layer is preferably 10% by mass to 95% by mass and more preferably 20% by mass to 90% by mass in the total solid content of the upper recording layer.

<Infrared absorber>
The positive recording layer in the present invention contains an infrared absorber, which is a component that exhibits a photothermal conversion function. This infrared absorber has a function of converting the absorbed infrared rays into heat, and the laser scanning causes the cancellation of the interaction, the decomposition of the development inhibitor, the generation of acid, etc., and the solubility in the developer is greatly increased. . In addition, the infrared absorber itself may interact with the alkali-soluble resin to suppress alkali solubility.
When the recording layer has a multilayer structure, such an infrared absorber may be contained in at least one of the upper recording layer and the lower recording layer, but is preferably contained in the upper recording layer from the viewpoint of sensitivity.
In addition, when included in the lower recording layer, when used in combination with a specific polymer and an insoluble alkali-soluble polymer, the infrared absorber is contained in another alkali-soluble polymer that forms the dispersed phase, and the dispersed phase absorbs infrared rays. It is considered that the agent is localized and the interaction release property is improved or the decomposition property is improved when the acid generator is contained.
The infrared absorber used in the present invention is a dye or pigment that effectively absorbs infrared rays having a wavelength of 760 nm to 1200 nm. A dye or pigment having an absorption maximum at a wavelength of 760 nm to 1200 nm is preferable.

The infrared absorber that can be suitably used for the lithographic printing plate precursor according to the invention will be described in detail below.
As the dye, commercially available dyes and known dyes described in documents such as “Dye Handbook” (edited by the Society for Synthetic Organic Chemistry, published in 1970) can be used. Specifically, dyes such as azo dyes, metal complex azo dyes, pyrazolone azo dyes, naphthoquinone dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinoneimine dyes, methine dyes, cyanine dyes, squarylium dyes, pyrylium salts, metal thiolate complexes, etc. Is mentioned.

  Preferred dyes include, for example, cyanine dyes described in JP-A-58-125246, JP-A-59-84356, JP-A-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).
Among these dyes, particularly preferred are cyanine dyes, squarylium dyes, pyrylium salts, and nickel thiolate complexes.

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

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

  These pigments may be used without surface treatment, or may be used after surface treatment. The surface treatment method includes a method of surface coating with a resin or wax, a method of attaching a surfactant, a method of bonding a reactive substance (eg, silane coupling agent, epoxy compound, polyisocyanate, etc.) to the pigment surface, etc. Can be considered. The above-mentioned surface treatment methods are described in “Characteristics and Applications of Metal Soap” (Yokoshobo), “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, preferably in the range of 0.05 μm to 1 μm, from the viewpoint of the stability of the recording layer coating liquid and the uniformity of the recording layer to be formed. Is more preferable, and it is particularly preferable to be 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).

  Since the lithographic printing plate precursor of the present invention has a positive recording layer, the positive action is caused by the interaction with the binder polymer having a specific functional group (dissolution in the unexposed area is suppressed in an alkaline developer, and It is preferable to use an infrared absorber that causes the dissolution inhibiting action to be released, and in that respect, those having an onium salt structure are particularly preferable. Specifically, among the above-described infrared absorbers, cyanine dyes and pyrylium salts are particularly preferable. The details of the cyanine dye and the pyrylium salt are as described above.

Furthermore, an anionic infrared absorber described in JP-A-11-338131 can also be suitably used. This anionic infrared absorber refers to one having an anion structure without a cation structure in the mother nucleus of a dye that substantially absorbs infrared rays.
For example, (a-1) anionic metal complex and (a-2) anionic phthalocyanine are mentioned.
Here, the (a-1) anionic metal complex refers to an anion that becomes an anion in the central metal and the entire ligand of the complex part that substantially absorbs light.
(A-2) Anionic phthalocyanine refers to a phthalocyanine skeleton having an anion group such as a sulfonic acid, a carboxylic acid, or a phosphonic acid group bonded as a substituent to form an anion as a whole.
Furthermore, an anionic infrared absorber represented by [Ga ⁻ -M-Gb] _m X ^{m +} described in [0014] to [0105] of JP-A-11-338131 [Ga ⁻ represents an anionic substituent, and Gb represents Represents a neutral substituent. X ^{m +} represents a 1 to m-valent cation containing a proton, and m represents an integer of 1 to 6. Can be mentioned.

  The infrared absorber is preferably a dye, and suitable examples include infrared absorbers having an onium salt structure described in paragraphs [0018] to [0034] of JP-A No. 11-291605.

  For the purpose of further improving the sensitivity and development latitude, the recording layer is used in combination with an infrared absorber that exhibits the ability to suppress dissolution of the above cyanine dyes, pyrylium salts, anionic dyes, and other dyes or pigments. You can also

  In the present invention, in the case of a single recording layer, the content of the infrared absorber is preferably 2% by mass to 20% by mass and preferably 3% by mass to 15% by mass in the total solid content. More preferred. Further, in the case of a recording layer having a multi-layer structure, from the viewpoint of image formability and suppression of occurrence of stains in the non-image area, the lower recording layer and other recording layers have a total solid content of 0.01 to It is preferable to add 50 mass%, More preferably, it is 0.1-20 mass%, More preferably, it is 0.5-15 mass%.

When the infrared absorber is contained in the recording layer in which the dispersed phase is formed by using two or more kinds of polymers in combination, it may be contained in either the matrix phase or the dispersed phase. May be. When the latex constituting the dispersed phase as described above contains desired components such as an initiator and an infrared absorber, it may be added together with raw materials when forming latex particles, or may be introduced after forming the latex. .
Examples of the method of introducing after forming the latex include a method in which desired components such as an initiator, a color system, and a crosslinking agent to be introduced are dissolved in an organic solvent and added to a dispersion medium.

上記式において、Ｒ¹¹〜Ｒ¹⁶はそれぞれ任意の置換基を表し、好ましくは水素原子、ハロゲン原子、炭素数１〜６の直鎖アルキル、炭素数１〜６の枝分かれアルキル、炭素数１〜６のアルコキシを表す。特に好ましくは、水素原子、炭素数１〜３のアルキル基、炭素数１〜３のアルコキシル基、クロル原子、臭素原子を表す。Ｘは有機もしくは無機の対アニオンを表す。特にスルホニウム塩が好ましい。 <Sulfonium salt having an aromatic group / iodonium salt>
When the recording layer has a multilayer structure, the sulfonium salt and / or iodonium salt having an aromatic group may be contained in at least one of the upper recording layer and the lower recording layer. From the viewpoint of sensitivity, the upper recording layer It is preferable that it is contained in.
As the sulfonium salt and iodonium salt having an aromatic group, for example, compounds described in JP-A Nos. 2001-133969 and 2002-268217 can be used. Examples of the sulfonium salt and the iodonium salt having an aromatic group include compounds having a structure represented by the following general formula.

In the above formula, R ^{11 to} R ¹⁶ each represent an arbitrary substituent, preferably a hydrogen atom, a halogen atom, a linear alkyl having 1 to 6 carbon atoms, a branched alkyl having 1 to 6 carbon atoms, or a 1 to 6 carbon atoms. Represents alkoxy. Particularly preferably, it represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, an alkoxyl group having 1 to 3 carbon atoms, a chloro atom, or a bromine atom. X represents an organic or inorganic counter anion. A sulfonium salt is particularly preferable.

Specific examples of the sulfonium salt and iodonium salt having an aromatic group are shown below.

  In the present invention, at least one selected from the sulfonium salt and iodonium salt having these aromatic groups is the total solid content in the case of a single recording layer from the viewpoint of image formation and prevention of stains in the non-image area. The content is suitably 0.01 to 50% by mass, preferably 0.1 to 25% by mass, more preferably 0.5 to 20% by mass. In the case of a recording layer having a multilayer structure, the content is suitably 0.01 to 50% by weight, preferably 0.1 to 25% by weight, more preferably 0, based on the total solid content of the layer to be contained. 0.5 to 20% by mass.

  In the recording layer of the lithographic printing plate precursor according to the invention, in addition to the specific polymer and the novolak resin, other known alkali-soluble polymers can be used depending on the purpose. Other polymer compounds may be included. Examples of the polymer compound that can be contained include the polymer compounds described in JP-A-2008-64959, [0027] to [0044].

  It is preferable to add a fluoropolymer to each recording layer for the purpose of improving the development resistance of the image area. Examples of the fluorine-containing polymer used in the image recording layer include fluorine-containing monomer copolymers as described in JP-A Nos. 11-288093 and 2000-187318.

  Preferable specific examples of the fluoropolymer include acrylic polymers containing P-1 to P-13 fluorine described in JP-A-11-288093 and A described in JP-A-2000-187318. Examples thereof include fluorine-containing polymers obtained by copolymerizing acrylic monomers having fluorine atoms of −1 to A33 with any acrylic monomer.

  As the molecular weight of the fluorine-containing polymer mentioned above, those having a weight average molecular weight of 2000 or more and a number average molecular weight of 1000 or more are preferably used. More preferably, the weight average molecular weight is 5000 to 300000, and the number average molecular weight is 2000 to 250,000.

  In addition, as the fluorine-containing polymer, a commercially available fluorine-based surfactant that is a compound having the preferred molecular weight can also be used. As specific examples, MegaFuck F-171, F-173, F-176, F-183, F-184, F-780, F-781 (all trade names) manufactured by Dainippon Ink & Chemicals, Inc. are used. Can be mentioned.

  These fluorine-containing polymers may be used alone or in combination of two or more. The addition amount is suitably 1.4% by mass or more based on the solid content of the image recording layer. A preferable addition amount is 1.4 to 5.0% by mass. When the amount is less than 1.4% by mass, the effect of improving the development latitude of the image recording layer, which is the purpose of adding the fluorine-containing polymer, may not be sufficiently obtained. Note that even if it exceeds 5.0 mass%, the effect of improving the development latitude is not improved, and on the contrary, there is a concern that the surface of the image recording layer becomes slightly soluble due to the influence of the fluorine-containing polymer and the sensitivity is lowered.

  If necessary, the lower recording layer or other recording layers in the present invention are thermally decomposable such as diazonium salt, ammonium salt, phosphonium salt, o-quinonediazide compound, aromatic sulfone compound, aromatic sulfonic acid ester compound, etc. In the state where it does not decompose, a substance (dissolution inhibitor) that substantially reduces the solubility of the alkaline water-soluble polymer compound can be used in combination. By adding a dissolution inhibitor, the ability to dissolve the image area into the developer is improved, and by adding this compound, an infrared absorber that does not form an interaction with an alkali-soluble resin should be used. Is also possible.

  Suitable examples include S.I. I. Schlesinger, Photogr. Sci. Eng. , 18, 387 (1974), T.A. S. Baletal, Polymer, 21, 423 (1980), diazonium salts described in JP-A-5-158230, US Pat. Nos. 4,069,055, 4,069,056, and JP-A-3-140140 Ammonium salts described in the C. Necker et al., Macromolecules, 17, 2468 (1984), C.I. S. Wenetal, Teh, Proc. Conf. Rad. Curing ASIA, p478 Tokyo, Oct (1988), U.S. Pat. Nos. 4,069,055 and 4,069,056,

As a dissolution inhibitor that can be used in the present invention, a diazonium salt is particularly preferable. 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, particularly preferred are alkyl aromatic sulfonic acids such as hexafluorophosphoric acid, triisopropylnaphthalenesulfonic acid and 2,5-dimethylbenzenesulfonic acid.

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 helps the solubility of the sensitive material system by both the effect of losing the ability to suppress the dissolution of the binder due to thermal decomposition and the change of o-quinonediazide itself into an alkali-soluble substance.
Examples of the o-quinonediazide compound used in the present invention include J. Although the compounds described in pages 339 to 352 of “Light Sensitive Systems” (John Wiley & Sons. Inc.) by Korser can be used, o-reacted with various aromatic polyhydroxy compounds or aromatic amino compounds. Preferred are sulfonic acid esters or sulfonic acid amides of quinonediazide. Further, benzoquinone (1,2) -diazidosulfonic 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- described in U.S. Pat. Nos. 3,046,120 and 3,188,210. Esters of 5-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 1 to 50% by mass, more preferably 5 to 30% by mass, and particularly preferably 10 to 30% by mass with respect to the total solid content of each recording layer. These compounds can be used alone, but may be used as a mixture of several kinds.
The amount of additives other than the o-quinonediazide compound is preferably 1 to 50% by mass, more preferably 5 to 30% by mass, and particularly preferably 10 to 30% by mass.

  Further, for the purpose of enhancing the discrimination of the image and the resistance to scratches on the surface, a perfluoroalkyl group having 3 to 20 carbon atoms in the molecule as described in JP-A-2000-87318. A polymer having 2 or 3 (meth) acrylate monomers as polymerization components can be used in combination.

  Further, for the purpose of further improving sensitivity, cyclic acid anhydrides, phenols, and organic acids can be used in combination. Examples of cyclic acid anhydrides include phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, 3,6-endooxy-Δ4-tetrahydrophthalic anhydride described in US Pat. No. 4,115,128, Trachlorophthalic anhydride, maleic anhydride, chloromaleic anhydride, α-phenylmaleic anhydride, succinic anhydride, pyromellitic anhydride and the like can be used. As phenols, bisphenol A, p-nitrophenol, p-ethoxyphenol, 2,4,4′-trihydroxybenzophenone, 2,3,4-trihydroxybenzophenone, 4-hydroxybenzophenone, 4,4 ′, 4 “-Trihydroxytriphenylmethane, 4,4 ′, 3”, 4 ”-tetrahydroxy-3,5,3 ′, 5′-tetramethyltriphenylmethane and the like. There are sulfonic acids, sulfinic acids, alkylsulfuric acids, phosphonic acids, phosphoric acid esters, carboxylic acids, and the like described in Japanese Laid-Open Patent Application No. 60-88942 and Japanese Laid-Open Patent Publication No. 2-96755. 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-methoxybenzoic acid, phthalic acid, terephthalic acid, 4-cyclohexene-1,2 -Dicarboxylic acid, erucic acid, lauric acid, n-undecanoic acid, ascorbic acid, etc. The proportion of the cyclic acid anhydride, phenols and organic acids in the solid content of the recording layer is 0.05-20. % By mass is preferable, more preferably 0.1 to 5% by mass, and particularly preferably 0.1 to 10% by mass.

  For example, a dye having a large absorption in the visible light region can be added to the recording layer in the present invention as an image colorant. Specifically, Oil Yellow # 101, Oil Yellow # 103, Oil Pink # 312, Oil Green BG, Oil Blue BOS, Oil Blue # 603, Oil Black BY, Oil Black BS, Oil Black T-505 (orientated chemistry) Manufactured by Kogyo Co., Ltd.), Victoria Pure Blue, Crystal Violet (CI42555), Methyl Violet (CI42535), Ethyl Violet, Rhodamine B (CI145170B), Malachite Green (CI42000), Methylene Blue (CI52015), Eisenspiron Blue C-RH ( Hodogaya Chemical Co., Ltd.) and the dyes described in JP-A-62-293247.

  By adding these dyes, the image portion and the non-image portion are clearly distinguished after the image formation, so that it is preferable to add them. The addition amount is preferably in the range of 0.01 to 10% by mass with respect to the total solid content of the recording layer.

  Further, in the recording layer in the present invention, a nonionic surfactant as described in JP-A-62-251740 and JP-A-3-208514 is used in order to broaden the processing stability against the development conditions. , Amphoteric surfactants as described in JP-A-59-121044 and JP-A-4-13149, siloxane-based compounds as described in EP950517, JP-A-11-288093 Copolymers containing fluorine monomers as described can be added.

Specific examples of the nonionic surfactant include sorbitan tristearate, sorbitan monopalmitate, sorbitan trioleate, stearic acid monoglyceride, polyoxyethylene nonylphenyl ether and the like. Specific examples of the double-sided activator include alkyldi (aminoethyl) glycine, alkylpolyaminoethylglycine hydrochloride, 2-alkyl-N-carboxyethyl-N-hydroxyethylimidazolinium betaine and N-tetradecyl-N, N-betaine. Type (for example, trade name “Amorgen K” manufactured by Daiichi Kogyo 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- manufactured by Chisso Corporation. And polyalkylene oxide-modified silicones such as 732, DBP-534, and Tego Glide 100 manufactured by Tego, Germany.
The proportion of the nonionic surfactant and amphoteric surfactant in the recording layer is preferably 0.05 to 15% by mass, more preferably 0.1 to 5% by mass.

To the lithographic printing plate precursor according to the invention, a printing-out agent for obtaining a visible image immediately after heating by exposure or a dye or pigment as an image colorant can be added. Typical examples of the printing-out agent include 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, for example, combinations of o-naphthoquinonediazide-4-sulfonic acid halides and salt-forming organic dyes described in JP-A Nos. 50-36,209 and 53-8128, Trihalomethyl compounds and salts described in JP-A Nos. 53-36223, 54-74728, 60-3626, 61-143748, 61-151644 and 63-58440 Examples of such trihalomethyl compounds include oxazole-based compounds and triazine-based compounds, both of which have excellent temporal stability and give clear printout images. Examples of other photoacid releasing agents include various o-naphthoquinonediazide compounds described in JP-A-55-62444; 2-trihalomethyl-5--5 described in JP-A-55-77742. Examples include aryl-1,3,4-oxadiazole compounds; diazonium salts.

[Coating solvent and coating method]
When the lithographic printing plate precursor according to the present invention has a single-layer structure, a coating solution in which components such as a polymer compound and an infrared absorber are dissolved in a solvent is prepared and applied to a support having a hydrophilic surface. Can be manufactured.
Also in the case of a multilayer structure, a coating solution in which components such as the polymer compound and infrared absorber contained in the lower layer and the upper layer are dissolved in a solvent is prepared, and the lower layer coating solution is formed on a support having a hydrophilic surface. By applying the upper layer coating solution in this order, the lower layer and the upper layer can be produced and formed on the support.
Further, depending on the purpose, a protective layer, a resin intermediate layer, a backcoat layer and the like which will be described later 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, toluene, and the like. It is not limited to. These solvents are used alone or in combination.
The concentration of the above components (total solid content including additives) in the coating solution is preferably 1 to 50% by mass.

In addition, the solid coating amount on the support obtained after coating and drying is preferably 0.5 to 3.0 g / m ² , particularly preferably 0.8 to 2.0 g / m ² in the case of a single layer. is there.
In the case of a multi-layer structure, the upper layer is preferably 0.05 to 2.0 g / m ² and the lower layer is preferably 0.3 to 5.0 g / m ² , more preferably the upper layer is 0.1 to 1.0 g / m ^2. , lower in the range of 0.5 to 3.0 g / m ^2. Moreover, 0.05-1 are preferable, and, as for ratio (upper layer / lower layer) of the coating amount of an upper layer and a lower layer, More preferably, it is the range of 0.1-0.8.

  Various methods can be used as a method for applying each coating solution. Examples thereof include bar coater coating, spin coating, spray coating, curtain coating, dip coating, air knife coating, blade coating, and roll coating. be able to. As the coating amount decreases, the apparent sensitivity increases, but the film properties of the photosensitive film deteriorate.

[Support]
As the support used in the lithographic printing plate precursor according to the invention, a support having a hydrophilic surface is used.
The support is a dimensionally stable plate-like material and is not particularly limited as long as it satisfies physical properties such as necessary strength and flexibility. For example, paper, plastic (for example, polyethylene, polypropylene, Paper, metal plates (eg, aluminum, zinc, copper), plastic films (eg, cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene) Terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, etc.), paper laminated with metal as described above, or vapor-deposited paper, or plastic film.

As a support that can be applied to a lithographic printing plate precursor, 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 mainly composed of aluminum containing a trace amount of foreign elements, and may be a plastic film on which aluminum is laminated or vapor-deposited.
Examples of the different 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, but completely pure aluminum is difficult to produce in the refining technique, and may contain slightly different elements.

  As described above, the composition of the aluminum plate applicable 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 0.12 mm to 0.4 mm.

  The aluminum plate is roughened and used with a hydrophilic surface. Prior to the roughening, the surface of the aluminum plate is removed if desired. For example, a degreasing treatment with a surfactant, an organic solvent or an alkaline aqueous solution is performed. Done.

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 brush 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 Japanese Patent Laid-Open No. 54-63902, a method in which both are combined can also be used.
Among these, it is preferable to include a step of roughening at least in a hydrochloric acid electrolyte.

The roughened aluminum plate is subjected to alkali etching treatment and neutralization treatment as necessary, and then subjected to anodization 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.
When the amount of the anodized film is less than 1.0 g / m ² , the printing durability is insufficient, or the non-image part of the lithographic printing plate precursor is easily scratched, and ink adheres to the scratched part during printing. The so-called “scratch stain” is likely 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, it is disclosed in potassium fluoride zirconate disclosed in Japanese Patent Publication No. 36-22063 and US Pat. Nos. 3,276,868, 4,153,461, and 4,689,272. A method of treating with polyvinylphosphonic acid is used.

(Undercoat layer)
The lithographic printing plate precursor according to the invention has a lower layer as described above on a support, but an undercoat layer can be provided between the support and the lower layer as necessary.
By providing this undercoat layer, the undercoat layer between the support and the lower layer functions as a heat insulating layer, and heat generated by the exposure of the infrared laser does not diffuse to the support and is used efficiently. There is an advantage that sensitivity can be improved.
In addition, since the lower layer according to the present invention is located on the exposed surface or in the vicinity thereof even when the undercoat layer is provided, the sensitivity to the infrared laser is favorably maintained.
In the unexposed area, the lower layer itself, which is impermeable to the alkaline developer, functions as a protective layer for the undercoat layer, so that an image with excellent development stability and excellent discrimination is formed. In addition, it is considered that stability over time is also ensured.
In the exposed area, the lower layer component whose dissolution inhibiting ability is released is quickly dissolved and dispersed in the developer, and further, the undercoat layer itself adjacent to the support is made of an alkali-soluble polymer. Therefore, the solubility in the developer is good.For example, even when a developer with reduced activity is used, it dissolves quickly without the formation of a residual film, contributing to the improvement of the developability. This subbing layer is considered useful.

  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.

式中、Ｒ¹¹は水素原子、ハロゲン原子又はアルキル基を表し、Ｒ¹²及びＲ¹³はそれぞれ独立して、水素原子、水酸基、ハロゲン原子、アルキル基、置換アルキル基、アリール基、置換アリール基、−ＯＲ¹⁴、−ＣＯＯＲ¹⁵、−ＣＯＮＨＲ¹⁶、−ＣＯＲ¹⁷若しくは−ＣＮを表す。尚、Ｒ¹²及びＲ¹³が結合して環を形成してもよい。Ｒ¹⁴〜Ｒ¹⁷はそれぞれ独立してアルキル基又はアリール基を表し、Ｘは水素原子、金属原子、ＮＲ¹⁸Ｒ¹⁹Ｒ²⁰Ｒ²¹を表し、Ｒ¹⁸〜Ｒ²¹はそれぞれ独立して、水素原子、アルキル基、置換アルキル基、アリール基若しくは置換アリール基を表すか、又はＲ¹⁸及びＲ¹⁹が結合して環を形成してもよく、ｍは１〜３の整数を表す。 Furthermore, an undercoat layer containing at least one compound selected from the group of organic polymer compounds having a structural unit represented by the following formula is also preferred.

In the formula, R ¹¹ represents a hydrogen atom, a halogen atom or an alkyl group, and R ¹² and R ¹³ each independently represent a hydrogen atom, a hydroxyl group, a halogen atom, an alkyl group, a substituted alkyl group, an aryl group, a substituted aryl group, -OR ^14, -COOR ^15, represents a -CONHR ^16, -COR ¹⁷ or -CN. R ¹² and R ¹³ may combine to form a ring. R ^{14 to} R ¹⁷ each independently represents an alkyl group or an aryl group, X represents a hydrogen atom, a metal atom, or NR ¹⁸ R ¹⁹ R ²⁰ R ²¹ , and R ^{18 to} R ²¹ each independently represents a hydrogen atom , An alkyl group, a substituted alkyl group, an aryl group or a substituted aryl group, or R ¹⁸ and R ¹⁹ may be bonded to form a ring, and m represents an integer of 1 to 3.

Moreover, as a suitable undercoat layer component in the present invention, there can be mentioned a polymer compound having a structural unit having an acid group and a structural unit having an onium group, as described in JP-A No. 2000-241962.
Specific examples include a copolymer of a monomer having an acid group and a monomer having an onium group.
An acid group having an acid dissociation index (pKa) of 7 or more is preferred as the acid group, and more preferably —COOH, —SO ₃ H, —OSO ₃ H, —PO ₃ H ₂ , —OPO ₃ H ₂ , — CONHSO ₂ — or —SO ₂ NHSO ₂ —, particularly preferably —COOH.
Specific examples of the monomer having an acid group include acrylic acid, methacrylic acid, crotonic acid, isocrotonic acid, itaconic acid, maleic acid, maleic anhydride, and styrene having the acid group.
Preferred as the onium group is an onium group composed of Group V or Group VI atoms, more preferably an onium group composed of nitrogen, phosphorus or sulfur atoms, and particularly preferably an onium group composed of nitrogen atoms. It is a group. Specific examples of the monomer having an onium group include styrene having a substituent containing an onium group such as a methacrylate having an ammonium group in the side chain, a methacrylamide, a substituent containing an onium group such as a quaternary ammonium group, and the like. It is done.
Furthermore, compounds as described in JP-A No. 2000-108538, Japanese Patent Application No. 2002-257484, Japanese Patent Application No. 2003-78699, and the like can be used as necessary.

  These undercoat layers 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 and dried with water or the like to provide an undercoat layer.

In the former method, a solution having a concentration of 0.005 to 10% by mass of the 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.
In addition, a yellow dye can be added to the undercoat layer in order to improve the tone reproducibility of the image recording material.

The coating amount of the undercoat layer is suitably ² to 200 mg / m ² , preferably 5 to 100 mg / m ² . If the coating amount is less than 2 mg / m ² , sufficient printing durability cannot be obtained. Moreover, even if it is larger than 200 mg / m ^2, it is the same.

〔exposure〕
The planographic printing plate precursor of the present invention is image-formed by heat. Specifically, an image is formed by exposure with a solid-state high-power infrared laser such as a semiconductor laser or a YAG laser that emits infrared light having a wavelength of 700 to 1200 nm.
Direct image-like recording by a thermal recording head or the like, high-illuminance flash exposure such as a xenon discharge lamp, or infrared lamp exposure can also be used.
The output of the infrared laser is preferably 100 mW or more, and a multi-beam laser device is preferably used in order to shorten the exposure time. The exposure time per pixel is preferably within 20 μsec, and the energy applied to the lithographic printing plate precursor is preferably from 10 to 500 mJ / cm ² .

〔developing〕
In the present invention, the lithographic printing plate precursor is preferably developed with an alkaline aqueous solution having a pH of 12 or higher that does not substantially contain an organic solvent. Here, “substantially free of organic solvent” means that it does not contain an organic solvent to the extent of causing inconvenience in terms of environmental health, safety, workability, etc. The ratio of the organic solvent in the developer is 0.5% by weight or less, preferably 0.3% by weight or less, and most preferably not contained at all. Moreover, although pH is 12.0 or more, More preferably, it is 12.0-14.0.

  A conventionally known alkaline aqueous solution can be used as the developer (hereinafter referred to as developer including the replenisher). For example, sodium silicate, potassium, trisodium phosphate, potassium, ammonium, dibasic sodium phosphate, potassium, ammonium, sodium carbonate, potassium, ammonium, sodium bicarbonate, potassium, Examples thereof include inorganic alkali salts such as ammonium, sodium borate, potassium, ammonium, sodium hydroxide, ammonium, potassium and lithium. Moreover, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, triisopropylamine, n-butylamine, monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, Organic alkali agents such as ethyleneimine, ethylenediamine, and pyridine are listed. These alkaline aqueous solutions may be used individually by 1 type, and may use 2 or more types together.

  Among the above alkaline aqueous solutions, one of the developing solutions that exert the effect according to the present invention is a so-called one containing an alkali silicate as a base, or containing an alkali silicate by mixing a silicon compound with a base. Another more preferable developer, which is an aqueous solution called “silicate developer” having a pH of 12 or more, does not contain an alkali silicate, and contains a non-reducing sugar (an organic compound having a buffering action) and a base. Silicate developer ".

In the silicate developer, the aqueous solution of alkali metal silicate is a ratio of silicon oxide SiO ₂ and alkali metal oxide M ₂ O (generally [SiO ₂ ] / [M ₂ O]). And the developing property can be adjusted by the concentration. For example, as disclosed in JP-A-54-62004, the molar ratio of SiO ₂ / Na ₂ O is 1.0 to 1.5 ( That is, [SiO ₂ ] / [Na ₂ O] is 1.0 to 1.5), and the content of SiO ₂ is 1 to 4% by mass of an aqueous solution of sodium silicate, or Japanese Patent Publication No. 57-7427. [SiO ₂ ] / [M] is 0.5 to 0.75 (ie, [SiO ₂ ] / [M ₂ O] is 1.0 to 1.5), total alkali _{metal 2} concentrations from 1 to 4 wt%, and the developing solution is present therein Based on the gram atom containing potassium at least 20%, aqueous solution of an alkali metal silicate it is preferably used.

In the case of a so-called “non-silicate developer” that does not contain an alkali silicate and contains a non-reducing sugar and a base, it is preferable to contain a non-reducing sugar having a buffering property that suppresses fluctuations in pH.
Non-reducing sugars are saccharides that do not have a free aldehyde group or ketone group and do not exhibit reducibility, trehalose-type oligosaccharides in which reducing groups are bonded, and glycosides in which reducing groups of saccharides are combined with non-saccharides. , And sugar alcohols reduced by hydrogenation of sugars, any of which can be used in the present invention. In the present invention, non-reducing sugars described in JP-A-8-305039 can be preferably used.

Examples of the trehalose type oligosaccharides include saccharose and trehalose. Examples of the glycoside include alkyl glycosides, phenol glycosides, and mustard oil glycosides. Examples of the sugar alcohol include D, L-arabit, rebit, xylit, D, L-sorbit, D, L-mannit, D, L-exit, D, L-talit, zulsiit, allozulcit and the like. . Further, maltitol hydrogenated to disaccharide maltose, reduced form obtained by hydrogenation of oligosaccharide (reduced water candy), and the like are preferable. Among these non-reducing sugars, trehalose-type oligosaccharides and sugar alcohols are preferable, and among them, D-sorbitol, saccharose, reduced syrup, etc. are preferable in that they have a buffering action in an appropriate pH region and are inexpensive.
These non-reducing sugars may be used alone or in combination of two or more.
The content of the non-reducing sugar in the non-silicate developer is preferably 0.1 to 30% by mass, and more preferably 1 to 20% by mass. When the content is in the range of 0.1 to 30% by mass, an appropriate buffer action is obtained, and it is preferable in terms of high concentration and cost reduction.

Examples of the base used in combination with the non-reducing sugar include conventionally known alkali agents such as inorganic alkali agents and organic alkali agents. Examples of the inorganic alkaline agent include sodium hydroxide, potassium hydroxide, lithium hydroxide, trisodium phosphate, tripotassium phosphate, triammonium phosphate, disodium phosphate, dipotassium phosphate, diammonium phosphate, Examples thereof include sodium carbonate, potassium carbonate, ammonium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, ammonium hydrogen carbonate, sodium borate, potassium borate, and ammonium borate.
Examples of the organic alkali agent include monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, triisopropylamine, n-butylamine, monoethanolamine, diethanolamine, triethanolamine, monoisopropanol. Examples include amine, diisopropanolamine, ethyleneimine, ethylenediamine, and pyridine.
The said base may be used individually by 1 type, and may use 2 or more types together. Among these bases, sodium hydroxide and potassium hydroxide are preferable. In the present invention, as the non-silicate developer, a non-reducing sugar alkali metal salt as a main component can be used instead of the non-reducing sugar and the base.

In addition, an alkaline buffer composed of a weak acid other than the non-reducing sugar and a strong base can be used in combination with the non-silicate developer. The weak acid preferably has a dissociation constant (pKa) of 10.0 to 13.2, and can be selected from, for example, those described in Ionization Constants of Organic Acids Solution issued by Pergmon Press.
Specifically, alcohols such as 2,2,3,3-tetrafluoropropanol-1, trifluoroethanol, and trichloroethanol, pyridine-2-aldehyde (, aldehydes such as pyridine-4-aldehyde (such as salicylic acid, 3-hydroxy-2-naphthoic acid, catechol, gallic acid, sulfosalicylic acid, 3,4-dihydroxysulfonic acid, 3,4-dihydroxybenzoic acid, hydroquinone (11.56), pyrogallol, o-, m-, p -Compounds having a phenolic hydroxyl group such as cresol, resorsonol, oximes such as acetoxime, 2-hydroxybenzaldehyde oxime, dimethylglyoxime, ethanediamide dioxime, acetophenone oxime, adenosine, inosine, guanine, cytosine, hypoxanthine, chitosan Nucleic acid-related substances such as Nchin, other, diethylaminomethyl acid, benzimidazole, and the like barbituric acid is preferably exemplified.

  Various surfactants and organic solvents can be added to the developer as necessary for the purpose of promoting or suppressing developability, dispersing development residue, or improving ink affinity of the printing plate image area. As the surfactant, anionic, cationic, nonionic and amphoteric surfactants are preferable. Furthermore, in the developer, if necessary, reducing agents such as sodium salt and potassium salt of inorganic acids such as hydroquinone, resorcin, sulfurous acid, and bisulfite, organic carboxylic acid, antifoaming agent, water softener, etc. Can be added.

The lithographic printing plate precursor developed using the developer is post-treated with a desensitizing solution containing washing water, a rinse solution containing a surfactant or the like, gum arabic or a starch derivative. As the post-treatment when the image forming material is used as a printing plate, these treatments can be used in various combinations.
Further, when developing using an automatic developing machine, the developer in the developing tank is replaced for a long time by using a developer obtained by adding an aqueous solution (replenisher) having a higher alkali strength than the developer to the developer. It is known that a large amount of PS plate can be processed without any problems. This replenishment method is also preferably applied in the present invention.
The printing plate developed with the developer is post-treated with a desensitizing solution containing washing water, a rinsing solution containing a surfactant and the like, gum arabic and starch derivatives. As the post-treatment of the lithographic printing plate precursor according to the invention, these treatments can be used in various combinations.

  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. A developing solution is sprayed from a spray nozzle. In addition, recently, a method is also known in which a printing plate is dipped and conveyed by a submerged guide roll 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 present invention, an image portion unnecessary for the lithographic printing plate precursor obtained by image exposure, development, washing and / or rinsing and / or gumming (for example, film edge trace of the original film). Etc.), the unnecessary image portion is erased. Such erasing is preferably performed by applying an erasing solution as described in, for example, Japanese Patent Publication No. 2-13293 to an unnecessary image portion, leaving it for a predetermined time, and then washing with water. As described in JP-A-59-174842, a method of developing after irradiating an unnecessary image portion with an actinic ray guided by an optical fiber can also be used.

The lithographic printing plate precursor obtained as described above can be subjected to a printing process after applying a desensitized gum if desired, but if it is desired to make a lithographic printing plate precursor with a higher printing durability, A burning process is performed if desired.
When burning a lithographic printing plate precursor, it is described in JP-B-61-2518, JP-A-55-28062, JP-A-62-31859, JP-A-61-159655 before burning. It is preferable to treat with a surface conditioning liquid.
As a method thereof, a method of applying the lithographic printing plate precursor with a sponge or absorbent cotton soaked with the surface-adjusting liquid, or immersing and applying the printing plate 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). The lithographic printing plate precursor coated with the surface-adjusting solution is dried if necessary, and then heated to a high temperature with a burning processor (for example, burning processor “BP-1300” sold by Fuji Photo Film Co., Ltd.). Is done. In this case, the heating temperature and time are in the range of 180 to 300 ° C. and preferably in the range of 1 to 20 minutes, although depending on the type of components forming the image.

  The lithographic printing plate precursor 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, so-called desensitizing treatment such as gumming can be omitted. The lithographic printing plate precursor obtained by such treatment is applied to an offset printing machine or the like and used for printing a large number of sheets.

EXAMPLES Hereinafter, although this invention is demonstrated according to an Example, the scope of the present invention is not limited to these Examples.
[Example 1]
Using a JIS-A-1050 aluminum plate having a thickness of 0.3 mm, a support A was produced by processing through the following steps.
The above aluminum plate was sprayed with an aqueous NaOH solution (concentration 26 mass%, aluminum ion concentration 6.5 mass%) at a temperature of 70 ° C. to dissolve the aluminum plate 6 g / m ² . Thereafter, washing with water was performed using well water.
Next, desmutting treatment was performed by spraying with a 1% by weight aqueous solution of nitric acid having a temperature of 30 ° C. (containing 0.5% by weight of aluminum ions), and then washed with water by spraying.
An electrochemical surface roughening treatment was continuously performed 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 450 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.

The aqueous solution having a caustic soda concentration of 26 wt%, performed an aluminum ion concentration of 6.5 wt% to etching treatment by spraying at 32 ° C., the aluminum plate 0.10 g / m ² was dissolved, electrochemical by using the alternating current in the previous stage The smut component mainly composed of aluminum hydroxide generated during the roughening treatment 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.
A desmut treatment by spraying was performed with a 25% by mass aqueous solution of sulfuric acid at a temperature of 60 ° C. (containing 0.5% by mass of aluminum ions), and then water washing by spraying was performed using well water.
Subsequently, anodizing treatment was performed. The electrolytic solution had a sulfuric acid concentration of 170 g / liter (containing 0.5% by mass of aluminum ions) and a temperature of 43 ° C. Thereafter, washing with water was performed using well water.
When the surface roughness of the aluminum plate obtained so far was measured with a stylus tip diameter of 2 μm using a surfcom manufactured by Tokyo Seimitsu Co., Ltd., it was 0.45 μm in Ra display.
Both current densities were about 30 A / dm ² . The final oxide film amount was 2.7 g / m ² .
Further, an anodized aluminum plate was immersed for 5 seconds in a solution obtained by heating a 0.5% polyvinylphosphonic acid aqueous solution to 60 ° C., and washed with water by spraying.
Thus, a support A for a photosensitive lithographic printing plate was obtained.

The lower layer coating liquid A having the following composition was coated on the support obtained above with a wire bar, and then dried for 70 seconds in a drying oven set at 140 ° C. to obtain a lower layer. The coating amount after drying was 1.0 g / m ² .
<Coating liquid A for lower layer>
・ Specific polymer (structure example (1) above) 0.80g
-Crystal violet naphthalene sulfonate 0.10g
・ Fluorine-based surfactant F-780-F (Dainippon Ink Co., Ltd.) 0.01g
・ Methyl ethyl ketone 5.00g
・ 1-methoxy-2-propanol 5.00g
・ N, N-dimethylformamide 10.00g

・フッ素系界面活性剤Ｆ−７８０−Ｆ（大日本インキ(株)製） ０．０２ｇ
・メチルエチルケトン １０．００ｇ
・１−メトキシ−２−プロパノール １０．００ｇ
このようにして、記録層が重層構造である感光性平版印刷版原版を得た。 On the lower layer thus obtained, an upper layer coating solution B having the following composition was coated with a wire bar, and then dried for 60 seconds in a drying oven set at 130 ° C. to obtain an upper layer. The coating amount after drying was 0.5 g / m ² .
<Upper layer coating solution B>
・ The above-mentioned novolac resin (i) 0.80 g
(Novolak resin consisting of phenol / m-cresol / p-cresol = 50/30/20 (molar ratio), weight average molecular weight 8,000)
・ Sulphonium salt having an aromatic group (the above example (A)) 0.20 g
・ Cyanine dye P of the following structure: 0.10 g

・ Fluorine-based surfactant F-780-F (Dainippon Ink Co., Ltd.) 0.02g
・ Methyl ethyl ketone 10.00g
1-methoxy-2-propanol 10.00g
Thus, a photosensitive lithographic printing plate precursor having a multi-layered recording layer was obtained.

[Example 2] to [Example 14]
Photosensitive lithographic printing in the same manner as in Example 1 except that the specific polymer (1) in the lower layer, the novolak resin (i) in the upper layer, and the sulfonium salt (A) in Example 1 were changed to the compounds shown in Table 1. I got the original version.
[Example 15]
In Example 1, a photosensitive lithographic printing plate precursor was obtained in the same manner as in Example 1 except that 0.10 g of the cyanine dye P used in the upper layer was also added to the lower layer.
[Example 16]
A photosensitive lithographic printing plate precursor was obtained in the same manner as in Example 15, except that the cyanine dye P was not used in the upper layer and the amount added to the lower layer was 0.15 g.

[Example 17]
In Example 1, the electrolyte used for the electrochemical surface roughening treatment in the preparation of the support A was changed to a 7.5 g / liter aqueous solution of hydrochloric acid (containing 5 g / liter of aluminum ions), and 10 g / liter of nitric acid. Example 1 except that the aqueous solution (containing 5 g / liter of aluminum ions) and the amount of electricity was 300 C / dm ^{2 in} terms of the total amount of electricity when the aluminum plate was an anode (this support is hereinafter referred to as support B). In the same manner, a photosensitive lithographic printing plate precursor was obtained. The surface roughness of the support B was measured with a stylus tip diameter of 2 μm using a surfcom manufactured by Tokyo Seimitsu Co., Ltd. and found to be 0.25 μm in Ra display.

・クリスタルバイオレットのナフタレンスルホン酸塩 ０．１０ｇ
・フッ素系界面活性剤Ｆ−７８０−Ｆ（大日本インキ(株)製） ０．０２ｇ
・メチルエチルケトン ５．００ｇ
・１−メトキシ−２−プロパノール ５．００ｇ
・Ｎ，Ｎ−ジメチルホルムアミド １０．００ｇ
このようにして、記録層が単層である感光性平版印刷版原版を得た。 [Example 18]
A coating liquid C having the following composition was applied to the support A obtained in Example 1 with a wire bar, and then dried in an oven for drying set at 140 ° C. for 80 seconds to obtain a recording layer. The coating amount after drying was 1.5 g / m ² .
<Coating liquid C>
・ Specific polymer (structure example (1) above) 0.50g
・ The above-mentioned novolak resin (i) 0.50 g
・ Sulfonium salt having an aromatic group (A) 0.10 g
・ Cyanine dye P of the following structure: 0.10 g

-Crystal violet naphthalene sulfonate 0.10g
・ Fluorine-based surfactant F-780-F (Dainippon Ink Co., Ltd.) 0.02g
・ Methyl ethyl ketone 5.00g
・ 1-methoxy-2-propanol 5.00g
・ N, N-dimethylformamide 10.00g
Thus, a photosensitive lithographic printing plate precursor having a single recording layer was obtained.

[Example 19] to [Example 31]
A photosensitive lithographic printing plate precursor was obtained in the same manner as in Example 18 except that the specific polymer (1), novolak resin (i) and sulfonium salt (A) were changed to the compounds shown in Table 1 in Example 18. It was.
[Example 32]
A photosensitive lithographic printing plate precursor was obtained in the same manner as in Example 18 except that the support B described in Example 17 was used instead of the support A in Example 18.

[Comparative Example 1]
In Example 1, instead of the specific polymer (1) in the lower layer, a copolymer of N- (p-aminosulfonylphenyl) methacrylamide / methyl methacrylate / acrylonitrile = 35/35/30 (molar ratio) (weight average) A photosensitive lithographic printing plate precursor was obtained in the same manner as in Example 1, except that a molecular weight of 65,000 was used (hereinafter referred to as polymer (X)).
[Comparative Example 2]
In Example 1, instead of the lower layer specific polymer (1), a copolymer of N-phenylmaleimide / methacrylamide / methacrylic acid = 45/35/20 (molar ratio) (weight average molecular weight 20,000, hereinafter polymer) A photosensitive lithographic printing plate precursor was obtained in the same manner as in Example 1, except that (Y) was used.

[Comparative Example 3]
A photosensitive lithographic printing plate precursor was obtained in the same manner as in Example 1 except that the lower layer sulfonium salt (A) was not used in Example 1.
[Comparative Example 4]
A photosensitive lithographic printing plate precursor was obtained in the same manner as in Example 18 except that instead of the specific polymer (1) in Example 18, the polymer (X) of Comparative Example 1 was used.

[Comparative Example 5]
A photosensitive lithographic printing plate precursor was obtained in the same manner as in Example 18 except that instead of the specific polymer (1) in Example 18, the polymer (Y) of Comparative Example 2 was used.
[Comparative Example 6]
A photosensitive lithographic printing plate precursor was obtained in the same manner as in Example 18 except that novolac resin (i) was not used and the amount of the specific polymer (1) was 1.00 g.
[Comparative Example 7]
A photosensitive lithographic printing plate precursor was obtained in the same manner as in Example 18 except that the sulfonium salt (A) was not used in Example 18.

[Evaluation of developability]
The obtained photosensitive lithographic printing plate was printed on a Fujifilm Corporation Luxel PLASETTER T-9800HS with a beam output of 100% and a drum rotation speed of 150 rpm, with a dot area ratio of 175 lpi / 2400 dpi of 1-99%. Drawing (exposure) was performed on an image of a test pattern containing a chart.
Next, development processing was performed using an Autolith PN85CE automatic developing machine manufactured by AGFA with a developer temperature of 30 degrees and a development time of 25 seconds. At this time, as a developing solution, a concentrated developing solution 1 having the following composition was diluted with water, and a developing solution whose conductivity was changed every 2 mS / cm between 80 and 100 mS / cm was used. As the gum solution, a solution obtained by diluting FG-1 manufactured by Fuji Film Co., Ltd. with water 1: 1. In this way, the developability was evaluated.
<Concentrated developer 1 composition>
・ No.3 sodium silicate (38.5% aqueous solution) 150g
・ 70 g of sodium hydroxide (50% aqueous solution)
・ Dipotassium salt of phosphoric acid (p-methylphenoxypolyoxyethylene) 10 g
・ Pluronic TR704 (manufactured by ADEKA Corporation) 2g
・ Eleminol MON-2 (manufactured by Sanyo Chemical Co., Ltd., 48.5% aqueous solution) 1 g
・ Pure water 267g

When the developer feel is low, development in the exposed area becomes insufficient and a residual film is generated in the non-image area. If the developer feels high, the surface of the unexposed area is developed and the film is reduced, and a good image cannot be obtained. Thus, the width of the electric conductivity of the developing solution in which both the residual film in the non-image area and the film reduction in the image area did not occur was evaluated for each lithographic printing plate precursor as an index of developability latitude. The results are shown in Table 1.
As shown in Table 1, the lithographic printing plate precursors obtained by the examples according to the present invention all had a wide range of the above-described conductivity, that is, a wide developability latitude and excellent developability. On the other hand, in the planographic printing plate precursor obtained by the comparative example, the conductivity range was narrower than that of the planographic printing plate precursor of the example.

[Evaluation of chemical resistance]
The obtained photosensitive lithographic printing plate precursor was exposed and developed in the same manner as the evaluation of developability described above to obtain a lithographic printing plate. As the developer at this time, a developer having an electric conductivity that becomes the center of the electric conductivity width found in the evaluation of developability was used.
Next, printing was performed using the lithographic printing plate thus obtained. At this time, the Lislon printer manufactured by Komori Corporation was used as the printing machine, the Varius G black ink manufactured by Dainippon Ink and Chemicals was used as the ink, and Fuji Film Co., Ltd. was used as the fountain solution. Each of IF-102 was diluted with water to a concentration of 4%. Further, every time 5000 sheets were printed, the plate surface was wiped with a multi-cleaner manufactured by Fuji Film Co., Ltd. Printing durability was evaluated based on the number of printed sheets when printed on high-quality paper and visually recognized that the density of the solid image started to decrease. A larger value means better chemical resistance. The results are shown in Table 1.
As shown in Table 1, all the plates made from the lithographic printing plate precursors obtained by the examples according to the present invention exhibited good chemical resistance. On the other hand, the plates from the lithographic printing plate precursors obtained by the comparative examples were all poor in chemical resistance.

[Burning Evaluation]
Of the obtained photosensitive lithographic printing plate precursors, the lithographic printing plate precursors of Examples (1) and (18) were exposed and developed in the same manner as in the evaluation of chemical resistance to obtain lithographic printing plates. .
Next, this plate was washed with water and the gum solution was dropped. Then, BC-5 manufactured by Fuji Film Co., Ltd. was included in the sponge as a surface-adjusting solution and dried naturally. Thereafter, it was heated at 260 ° C. for 5 minutes in a burning oven manufactured by Wisconsin. After cooling to room temperature and washing with water and dropping the surface-adjusting solution, gumming was performed using a gum coater G-800 manufactured by FUJIFILM Corporation. As a gum, a solution obtained by diluting GU-7 manufactured by Fuji Film Co., Ltd. 1: 1 with water was used.
The plate subjected to the burning treatment in this way was printed in the same manner as in the chemical resistance evaluation to evaluate the printing durability. As a result, it was found that 380,000 and 340,000 prints could be obtained, respectively, and that the chemical resistance was further improved by burning.

[Other evaluations]
Of the obtained photosensitive lithographic printing plate precursor, the photosensitive lithographic printing plate precursors of Examples (1) and (18) were exposed and developed in the same manner as in the evaluation of developability except that the developer was changed. A lithographic printing plate was obtained. As the developer, a concentrated developer 2 having the following composition was diluted with water to have a conductivity of 43 mS / cm. As a result, a good lithographic printing plate with no residual color or film loss was obtained, and a good printing plate could be obtained even with a developer containing no silicic acid component.
<Concentrated developer 2 composition>
・ Potassium hydroxide (48% aqueous solution) 200g
・ 450g sorbitol
・ Tripotassium citrate 100g
・ Pionine C-158G (Takemoto Yushi Co., Ltd.) 10g
・ 240g of pure water

  As shown in the above examples, according to the present invention, a photosensitive lithographic printing plate precursor excellent in both developability and chemical resistance can be obtained. This photosensitive lithographic printing plate precursor can also obtain higher printing durability by burning.

実施例15、16は、赤外線吸収染料を含めている層に差異がある。

Examples 15 and 16 differ in the layer containing the infrared absorbing dye.

Claims (3)

On a support having a hydrophilic surface, an alkali-soluble or swellable polymer having a structural unit represented by the following general formula (1), a novolac resin, an infrared absorber, and a sulfonium salt and an iodonium salt having an aromatic group A positive photosensitive lithographic printing plate precursor provided with a recording layer containing at least one selected from the above.

... (1)

(In the formula, R ¹ represents a hydrogen atom or a methyl group, X represents a single bond, —COO—, or —CONH—, and Ar ¹ and Ar ² each represents an aromatic group that may have a substituent. Or a heteroaromatic group, and Y represents —SO ₂ NH— or —NHSO ₂ —.) A recording layer containing an alkali-soluble or swellable polymer having a structural unit represented by the following general formula (1) is provided on a support having a hydrophilic surface, and a novolac resin, an infrared absorber, And a positive photosensitive lithographic printing plate precursor provided with a recording layer containing at least one selected from sulfonium salts and iodonium salts having an aromatic group.

... (1)

(In the formula, R ¹ represents a hydrogen atom or a methyl group, X represents a single bond, —COO—, or —CONH—, and Ar ¹ and Ar ² each represents an aromatic group that may have a substituent. Or a heteroaromatic group, and Y represents —SO ₂ NH— or —NHSO ₂ —.) 3. The positive electrode according to claim 1, wherein in the alkali-soluble or swellable polymer having the structural unit represented by the general formula (1), Ar ¹ represents an aromatic group, and Ar ² represents a heteroaromatic group. Type photosensitive lithographic printing plate precursor.