JP2008151929A - Plate making method for lithographic printing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plate making method for a lithographic printing plate capable of satisfying both of scratch resistance and sensitivity. <P>SOLUTION: The plate making method for the lithographic printing plate is characterized by developing an infrared-sensitive positive lithographic printing plate original having an image forming layer containing an infrared absorbing dye and a water-insoluble and alkali-soluble resin with an alkali developer containing a compound represented by general formula (1) after infrared exposure, wherein R<SB>1</SB>-R<SB>6</SB>each represent a hydrogen atom or an aliphatic hydrocarbon group; W represents a carbon atom-containing divalent linking group; and M<SB>1</SB>-M<SB>4</SB>each represent a hydrogen atom or an alkali metal cation. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

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

In recent years, the development of lasers has been remarkable. Particularly, solid lasers and semiconductor lasers having a light emitting region from the near infrared to the infrared can easily be obtained with high output and small size. These lasers are very useful as a scanning exposure light source when directly making a plate by scanning exposure based on a digital data signal sent from a computer or the like.
The planographic printing plate material refers to a material having a heat-sensitive layer or a photosensitive layer as an image forming layer. The positive lithographic printing plate material for an infrared laser has an alkaline aqueous solution-soluble binder resin and an IR dye (infrared absorbing dye) that absorbs infrared light and generates heat as a component of an image forming layer. In the unexposed area (image area), it acts as a dissolution inhibitor that substantially lowers the solubility of the binder resin by interacting with the binder resin. In the exposed area (non-image area), the IR dye and the binder are combined with the generated heat. The interaction with the resin weakens and dissolves in the alkaline developer, and the hydrophilic surface of the support is exposed to form a lithographic printing plate.

In general, positive lithographic printing plate materials for infrared lasers are easily damaged. For this reason, it is proposed that the film thickness of the image forming layer be relatively large. However, when the heat-sensitive layer or the light-sensitive layer is simply thickened, the interaction between the IR dye and the binder resin due to the heat is not weakened, resulting in a problem that the sensitivity is lowered. When the thickness of the heat-sensitive layer or the photosensitive layer is small, the film is easily damaged, and the compatibility between the scratch resistance and the sensitivity is an important issue. Furthermore, if the surface is made slippery with a wax agent or the like to improve the scratch resistance, the problem of deteriorating ink deposition has occurred. As countermeasures from the developer side, it is conceivable to increase the developer solubility of the heat-sensitive layer or the photosensitive layer as a means for improving the sensitivity, or to increase the pH of the alkali developer and develop under highly active conditions. In either case, the image part is damaged and does not solve the problem.
As a processing method of a lithographic printing plate precursor having both excellent scratch resistance and sensitivity, an alkali-soluble resin-containing layer is provided on a support, and an infrared absorber is included on the support to increase the solubility in an alkaline aqueous solution by infrared laser exposure. In a multilayer type lithographic printing plate precursor provided with a positive recording layer, the positive recording layer contains an alkali-soluble novolak resin containing xylenol as a constituent unit, and the plate is image-exposed, and then has a pH buffering property. Development with an alkaline developer containing an organic compound and a base has been proposed (see Patent Document 1). In addition, a lithographic printing plate precursor having a photosensitive layer containing a photothermal conversion substance and an alkali-soluble resin having a phenolic hydroxyl group, having a pH of 11 or more after laser exposure, and an alkali containing two or more development inhibitors It has been proposed to develop with a developer (see Patent Document 2).

JP 2002-357894 A JP 2003-107741 A

  An object of the present invention is to provide a plate making method of a lithographic printing plate capable of achieving both scratch resistance and sensitivity. More specifically, the object of the present invention is high sensitivity at the time of image formation and excellent scratch resistance, and the resulting lithographic printing plate exhibits good ink setting properties. It is to provide a method for making a lithographic printing plate in which adhesion to the plate is suppressed.

（式中、Ｒ₁ 、Ｒ₂ 、Ｒ₃ 、Ｒ₄ 、Ｒ₅ 及びＲ₆ はそれぞれ水素原子、脂肪族炭化水素基、を表す。Ｗは炭素原子を含む二価の連結基を表す。Ｍ₁ 、Ｍ₂ 、Ｍ₃ 及びＭ₄ はそれぞれ水素原子又はアルカリ金属カチオンを表す。） As a result of intensive studies to achieve the above problems, the present inventors have found that excellent image formation can be achieved by treating an infrared-sensitive positive lithographic printing plate precursor with a specific alkaline developer. The present invention has been completed.
Therefore, the present invention provides a compound represented by the following general formula (1) after infrared exposure of an infrared-sensitive positive lithographic printing plate precursor having an image forming layer containing an infrared-absorbing dye and a water-insoluble and alkali-soluble resin. There is a plate making method of a lithographic printing plate, characterized in that development processing is performed with an alkaline developer containing the lithographic printing plate.

(In the formula, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ and R ₆ each represent a hydrogen atom and an aliphatic hydrocarbon group. W represents a divalent linking group containing a carbon atom. M ₁ , M ₂ , M ₃ and M ₄ each represent a hydrogen atom or an alkali metal cation.)

In the infrared-sensitive positive lithographic printing plate precursor used in the plate making method of the present invention, the image forming layer provided on the lithographic printing plate support may be a single layer or a laminated structure (multilayer type). That is, an upper image-forming layer comprising an infrared absorbing dye and a water-insoluble and alkali-soluble resin provided at a position close to the surface (exposed surface), and a water-insoluble and provided at a side close to the support. It may consist of a lower layer containing an alkali-soluble resin.
Accordingly, in the present invention, the infrared sensitive positive lithographic printing plate precursor includes an upper image forming layer containing an infrared absorbing dye and a water-insoluble and alkali-soluble resin, and a lower layer containing a water-insoluble and alkali-soluble resin therebelow. It is also directed to plate making methods for lithographic printing plates.
As a preferred embodiment of the present invention, there is the plate making method, wherein the water-insoluble and alkali-soluble resin in the lower layer of the infrared sensitive positive planographic printing plate precursor is an acrylic resin.

The plate making method of the lithographic printing plate of the present invention makes it possible to achieve both scratch resistance and sensitivity. That is, according to the plate making method of the lithographic printing plate of the present invention, the sensitivity at the time of image formation can be increased, the plate making method of the present invention exhibits excellent scratch resistance, and the obtained lithographic printing plate has good ink adhesion. Can show flesh. In addition, there is very little adhesion of development residue to the plate during plate making, and stable development processing can be provided.
The compound of the above general formula (1) is contained in an aqueous solution, actively supplements Ca and Mg ions having a development-inhibiting action, and in addition to a chelating action that promotes solubilization by alkali, the structure of this compound It is considered that the development promoting action presumed to be due to the above contributes to high sensitivity.

First, an alkaline developer (hereinafter also simply referred to as a developer) used in the present invention will be described.
The alkaline developer used in the present invention can be used as a developer charged at the start of development (referred to as a development starter) or a development replenisher. Hereinafter, unless otherwise specified, the development starter and the development replenisher are collectively referred to as a developer.
The developer used in the present invention has an alkaline aqueous solution as a basic composition.
Examples of the alkaline aqueous solution include a developer comprising an alkali silicate or non-reducing sugar and a base, and those having a pH of 12.5 to 14.0 are particularly preferable. The alkali silicate exhibits alkalinity when dissolved in water, and examples thereof include alkali metal silicates such as sodium silicate, potassium silicate and lithium silicate, and ammonium silicate. The alkali silicate may be used alone or in combination of two or more.

The alkali aqueous solution is easy to develop by adjusting the mixing ratio and concentration of silicon oxide SiO ₂ which is a component of silicate and alkali oxide M ₂ O (M represents an alkali metal or ammonium group). Can be adjusted to. Among the alkaline aqueous solutions, those having a mixing ratio (SiO ₂ / M ₂ O: molar ratio) of the silicon oxide SiO ₂ and the alkali oxide M ₂ O of 0.5 to 3.0 are preferably in this range. In addition, a general-purpose aluminum plate is rarely etched as a support for a lithographic printing plate, and developability is good. SiO ₂ / M ₂ O (molar ratio) is more preferably 1.0 to 2.0.
The concentration of the alkali silicate in the developer is preferably 1 to 10% by mass, and 3 to 8% by mass with respect to the mass of the aqueous alkali solution, from the viewpoint of good developability and processing capability and convenience of waste liquid treatment. More preferably, 4 to 7% by mass is most preferable.

In a developer comprising a non-reducing sugar and a base, the non-reducing sugar means a saccharide that has no free aldehyde group or ketone group and therefore has no reducing property, and is a trehalose-type oligosaccharide in which reducing groups are bonded to each other. Glycosides in which saccharide reducing groups and non-saccharides are combined, and sugar alcohols reduced by hydrogenation of saccharides. Any of these can be preferably used in the present invention.
Examples of trehalose type oligosaccharides include saccharose and trehalose, and 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-digit, D, L-talit, dulcit, allozulcit, meso-inosit and the like. . Furthermore, maltitol obtained by hydrogenation of a disaccharide, a reduced form (reduced water candy) obtained by hydrogenation of an oligosaccharide, and the like can also be suitably exemplified.
Among the above, as the non-reducing sugar, sugar alcohol and saccharose are preferable, and among them, D-sorbite, mesoinosit, saccharose, and reduced starch syrup are more preferable because they have a buffering action in an appropriate pH range. These non-reducing sugars may be used alone or in combination of two or more. The proportion of the non-reducing sugar in the developer is preferably 0.1 to 30% by mass, more preferably 1 to 20% by mass.

In the alkali silicate or non-reducing sugar, an alkali agent as a base can be appropriately selected from conventionally known compounds and combined.
Examples of the alkali agent include sodium hydroxide, potassium hydroxide, lithium hydroxide, trisodium phosphate, tripotassium phosphate, triammonium phosphate, disodium phosphate, dipotassium phosphate, diammonium phosphate, carbonic acid. Inorganic alkaline agents such as sodium, potassium carbonate, ammonium carbonate, sodium bicarbonate, potassium bicarbonate, ammonium bicarbonate, sodium borate, potassium borate, ammonium borate, potassium citrate, tripotassium citrate, sodium citrate, etc. Is mentioned.
Furthermore, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, triisopropylamine, n-butylamine, monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, ethylene An organic alkali agent such as imine, ethylenediamine, pyridine and the like can also be suitably exemplified.
These alkaline agents may be used alone or in combination of two or more. Of these, sodium hydroxide and potassium hydroxide are preferred. The reason is that the pH can be adjusted in a wide pH range by adjusting the amount added to the non-reducing sugar. Further, trisodium phosphate, tripotassium phosphate, sodium carbonate, potassium carbonate and the like are preferable because they have a buffering action.

（式中、Ｒ₁ 、Ｒ₂ 、Ｒ₃ 、Ｒ₄ 、Ｒ₅ 及びＲ₆ はそれぞれ水素原子、脂肪族炭化水素基、を表す。Ｗは炭素原子を含む二価の連結基を表す。Ｍ₁ 、Ｍ₂ 、Ｍ₃ 及びＭ₄ はそれぞれ水素原子又はアルカリ金属カチオンを表す。）
上記式中Ｒ₁ 、Ｒ₂ 、Ｒ₃ 、Ｒ₄ 、Ｒ₅ 及びＲ₆ が表す脂肪族炭化水素基としては、炭素原子数１〜１０の飽和又は不飽和の直鎖又は分岐の炭化水素基が挙げられ、中でも炭素原子数１〜３の直鎖アルキル基が適当である。中Ｒ₁ 、Ｒ₂ 、Ｒ₃ 、Ｒ₄ 、Ｒ₅ 及びＲ₆は水素原子であることが好ましい。
上記式中、Ｗが表す炭素原子を含む二価の連結基としては、炭素原子数１〜１０の飽和又は不飽和の直鎖又は分岐の二価炭化水素基が挙げられ、中でも−Ｃ_mＨ_2m−（ｍが２〜５の整数の表す。）が適当であり、特に直鎖の構造が好ましく、−ＣＨ₂−ＣＨ₂−が最も好ましい。Ｍ₁ 、Ｍ₂ 、Ｍ₃ 及びＭ₄ が表すアルカリ金属カチオンとしては、ナトリウム、カリウム、リチウムが挙げられ、ナトリウムが好ましい。 The developer used in the present invention contains a compound represented by the following general formula (1).

(In the formula, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ and R ₆ each represent a hydrogen atom and an aliphatic hydrocarbon group. W represents a divalent linking group containing a carbon atom. M ₁ , M ₂ , M ₃ and M ₄ each represent a hydrogen atom or an alkali metal cation.)
In the above formula, the aliphatic hydrocarbon group represented by R ₁ , R ₂ , R ₃ , R ₄ , R ₅ and R ₆ is a saturated or unsaturated linear or branched hydrocarbon group having 1 to 10 carbon atoms. Among them, a linear alkyl group having 1 to 3 carbon atoms is suitable. R ₁ , R ₂ , R ₃ , R ₄ , R ₅ and R ₆ are preferably hydrogen atoms.
In the above formula, examples of the divalent linking group containing a carbon atom represented by W include a saturated or unsaturated linear or branched divalent hydrocarbon group having 1 to 10 carbon atoms, and in particular, —C _m H. _2m - is the appropriate (. m represents the integer of 2 to 5), in particular linear structure is preferable, -CH ₂ -CH ₂ - is most preferred. Examples of the alkali metal cation represented by M ₁ , M ₂ , M ₃ and M ₄ include sodium, potassium and lithium, with sodium being preferred.

Although the preferable specific example of a compound shown by General formula (1) below is given, it is not limited to these.

The compound represented by the general formula (1) can be synthesized by a method generally known to those skilled in the art.
In the developer, the compound represented by the general formula (1) can be used alone or in combination of two or more. The content of the compound represented by the general formula (1) in the developer is appropriately 0.01 to 3% by mass, preferably 0.02 to 1% by mass, and more preferably 0.02 to 0.5% by mass. %.
The compounds represented by the general formula (1) which are preferably used are the above (1-1) and (1-4).

Various surfactants, organic solvents, and the like can be added to the developer as necessary for the purpose of promoting and suppressing developability, dispersing development residue, and improving ink affinity of the printing plate image area.
The surfactant can be selected from nonionic, anionic, cationic or amphoteric surfactants.
Examples of nonionic surfactants include polyethylene glycols such as polyethylene glycol and polyethylene glycol polypropylene glycol block copolymers, polyethylene glycol alkyl ethers such as polyethylene glycol cetyl ether, polyethylene glycol stearyl ether, polyethylene glycol oleyl ether, and polyethylene glycol behenyl ether. Polyethylene glycol polypropylene glycol cetyl ether, polyethylene glycol polypropylene glycol decyl tetradecyl ether, etc. polyethylene glycol polypropylene glycol alkyl ethers, polyethylene glycol octyl phenyl ether, polyethylene glycol nonyl phenyl ether, etc. Polyethylene glycol fatty acid esters such as lenglycol alkylphenyl ethers, ethylene glycol monostearate, ethylene glycol distearate, diethylene glycol stearate, polyethylene glycol distearate, polyethylene glycol monolaurate, polyethylene glycol monostearate, polyethylene glycol monooleate Glyceryl monomyristate, glyceryl monostearate, glyceryl monoisostearate, glyceryl distearate, glyceryl monooleate, glyceryl dioleate and the like, and polyethylene oxide adducts thereof, sorbitan monopalmitate, mono Sorbitan stearate, sorbitan tristearate, mono Sorbitan fatty acid esters such as sorbitan oleate and sorbitan trioleate, and polyethylene oxide adducts thereof, sorbite monosorbate, sorbite tetrastearate, sorbite hexastearate, sorbite tetraoleate, and the like Examples thereof include polyethylene oxide adducts and polyethylene oxide adducts of castor oil.

  Examples of the anionic surfactant include fatty acid salts, abietic acid salts, hydroxyalkane sulfonic acid salts, alkane sulfonic acid salts, dialkyl sulfosuccinic acid ester salts, α-olefin sulfonic acid salts, linear alkyl benzene sulfonic acid salts, branched alkyl benzene sulfonic acid. Acid salts, alkylnaphthalene sulfonates, alkylphenoxy polyoxyethylenepropyl sulfonates, polyoxyethylene alkylsulfophenyl ether salts, N-methyl-N-oleyl taurine sodium salt, N-alkylsulfosuccinic acid monoamide disodium salt, Petroleum sulfonates, sulfated beef tallow oil, fatty acid alkyl ester sulfates, alkyl sulfate esters, polyoxyethylene alkyl ether sulfates, fatty acid compounds Glyceryl sulfate ester salt, polyoxyethylene alkyl phenyl ether sulfate ester salt, polyoxyethylene styryl phenyl ether sulfate ester salt, alkyl phosphate ester salt, polyoxyethylene alkyl ether phosphate ester salt, polyoxyethylene alkyl phenyl ether phosphate ester Preferable examples include salts, partially saponified products of styrene / maleic anhydride copolymer, partially saponified products of olefin / maleic anhydride copolymer, and naphthalene sulfonate formalin condensates.

Examples of the cationic surfactant include alkylamine salts, quaternary ammonium salts such as tetrabutylammonium bromide, polyoxyethylene alkylamine salts, and polyethylene polyamine derivatives.
Examples of amphoteric surfactants include carboxybetaines, alkylaminocarboxylic acids, sulfobetaines, aminosulfuric acid esters, imidazolines, and the like.
The surfactant concentration in the developer is suitably 0.001 to 10% by mass, more preferably 0.005 to 1% by mass, and most preferably 0.01 to 0.5% by mass.

The following additives can be added to the developer for the purpose of further improving the development performance.
For example, neutral salts such as NaCl, KCl and KBr described in JP-A-58-75152, chelating agents such as EDTA and NTA described in JP-A-58-190952, JP-A-59-121336 [Co (NH ₃ ) ₆ ] Cl ₃ , CoCl ₂ .6H ₂ O and other complexes described in JP-A-50-51324, sodium alkylnaphthalene sulfonate, n-tetradecyl-N, N-dihydroxy Anionic or amphoteric surfactants such as ethylbetaine, nonionic surfactants such as tetramethyldecynediol described in US Pat. No. 4,374,920, p described in JP-A-55-95946 -Cationic polymers such as methyl chloride quaternary compounds of dimethylaminomethyl polystyrene, disclosed in JP 56-142528 Amphoteric polymer electrolytes such as a copolymer of vinylbenzyltrimethylammonium chloride and sodium acrylate described above, reducing inorganic salts such as sodium sulfite described in JP-A-57-192951, JP-A-58-59444 Inorganic lithium compounds such as lithium chloride described in JP-A No. 59-75255, organometallic surfactants including organic Si and Ti described in JP-A-59-75255, and organoboron compounds described in JP-A-59-84241 And quaternary ammonium salts such as tetraalkylammonium oxide described in EP101010.

In addition, benzyl alcohol or the like is preferable as the organic solvent included in the developer. Moreover, addition of polyethylene glycol or a derivative thereof, or polypropylene glycol or a derivative thereof is also preferable.
Furthermore, if necessary, an inorganic salt-based reducing agent such as hydroquinone, resorcin, sulfurous acid or sodium or potassium hydrogen sulfite, an organic carboxylic acid, and an antifoaming agent can be added.

The aspect in which the alkaline developer is used in the plate making method of the present invention is not particularly limited.
In recent years, automatic developing machines for printing plate materials have been widely used in order to rationalize and standardize plate making operations, particularly in the plate making and printing industries.
This automatic developing machine is generally composed of a developing unit and a post-processing unit, and includes an apparatus for conveying a printing plate material, processing liquid tanks and a spray device. Each processing liquid pumped up is sprayed from a spray nozzle for development processing. In addition, recently, there is also known a method in which a printing plate material is immersed and conveyed in a processing liquid tank filled with a processing liquid by a submerged guide roll or the like. In the immersion development, the developer is preferably supplied uniformly to the plate surface, and the supply amount is preferably in the range of 0.5 to 10 ml / sec · cm ² . The amount of the developer supplied to the printing plate can be defined from the conveyance speed and the amount supplied by the means for supplying the developer. Examples of the means for supplying the developer include a spray device and convection by a circulation pump. In such automatic processing, each processing solution can be processed while being replenished with a replenisher according to the processing amount, operating time, and the like.

  In this case, by adding an aqueous solution having a higher alkali strength than the developer as a developer replenisher, a large amount of image forming material can be processed without changing the developer in the developer tank for a long time. When using an alkaline developer in the present invention, it is a preferred embodiment to employ this replenishment method. As the developing replenisher in that case, the above-described alkaline developer formulation can be used.

Next, an infrared sensitive positive planographic printing plate precursor to which the plate making method of the present invention is applied will be described.
The infrared-sensitive positive type lithographic printing plate precursor may have a single layer or a multilayer structure (multilayer type), that is, provided at a position close to the surface (exposed surface). The upper image forming layer containing a water-insoluble and alkali-soluble resin and an infrared-absorbing dye, and a lower layer containing a water-insoluble and alkali-soluble resin provided on the side close to the support may be used.
As an example of such a multilayer type light-sensitive material, a lithographic printing plate support comprising a lower layer containing a water-insoluble and alkali-soluble resin, a water-insoluble and alkali-soluble resin and an infrared absorbing dye, and dissolved in an alkaline aqueous solution by heating There is a heat-sensitive positive lithographic printing plate obtained by sequentially laminating an upper heat-sensitive layer having increased properties. Examples of the multilayer type light-sensitive material include those disclosed in JP-A Nos. 2001-166477 and 11-218914.
Hereinafter, the components of the image forming layer will be described.

[Water-insoluble and alkali-soluble resin]
The water-insoluble and alkaline water-soluble resin used in the present invention (hereinafter, appropriately referred to as alkali-soluble polymer) is a homopolymer containing acidic groups in the main chain and / or side chain in the polymer. Copolymers or mixtures thereof are included. Therefore, the image forming layer according to the present invention has a property of dissolving when contacted with an alkaline developer.

The alkali-soluble polymer used here is not particularly limited as long as it is a conventionally known polymer, but any functional group of (1) a phenolic hydroxyl group, (2) a sulfonamide group, and (3) an active imide group. It is preferable that it is a high molecular compound which has in a molecule | numerator.
For example, the following are exemplified, but not limited thereto.

  (1) Examples of the alkali-soluble polymer compound having a phenolic hydroxyl group include phenol formaldehyde resin, m-cresol formaldehyde resin, p-cresol formaldehyde resin, m- / p-mixed cresol formaldehyde resin, phenol / cresol (m- , P-, or m- / p-mixed), novolak resins such as mixed formaldehyde resins, and pyrogallol acetone resins. In addition to this, as the alkali-soluble polymer compound having a phenolic hydroxyl group, a polymer compound having a phenolic hydroxyl group in the side chain is preferably used. As a polymer compound having a phenolic hydroxyl group in the side chain, a polymerizable monomer comprising a low molecular compound having at least one unsaturated bond polymerizable with the phenolic hydroxyl group is homopolymerized, or other polymerizable property is added to the monomer. Examples thereof include a polymer compound obtained by copolymerizing monomers.

  Examples of the polymerizable monomer having a phenolic hydroxyl group used for obtaining a polymer compound having a phenolic hydroxyl group in the side chain include acrylamide, methacrylamide, acrylate ester, methacrylate ester, or hydroxystyrene having a phenolic hydroxyl group. Can be mentioned. Specifically, N- (2-hydroxyphenyl) acrylamide, N- (3-hydroxyphenyl) acrylamide, N- (4-hydroxyphenyl) acrylamide, N- (2-hydroxyphenyl) methacrylamide, N- (3 -Hydroxyphenyl) methacrylamide, N- (4-hydroxyphenyl) methacrylamide, o-hydroxyphenyl acrylate, m-hydroxyphenyl acrylate, p-hydroxyphenyl acrylate, o-hydroxyphenyl methacrylate, m-hydroxyphenyl methacrylate, p- Hydroxyphenyl methacrylate, o-hydroxystyrene, m-hydroxystyrene, p-hydroxystyrene, 2- (2-hydroxyphenyl) ethyl acrylate, 2- (3-hydroxyphenyl) Preferred are ethyl acrylate, 2- (4-hydroxyphenyl) ethyl acrylate, 2- (2-hydroxyphenyl) ethyl methacrylate, 2- (3-hydroxyphenyl) ethyl methacrylate, 2- (4-hydroxyphenyl) ethyl methacrylate, and the like. Can be used.

  Such resins having a phenolic hydroxyl group may be used in combination of two or more. Furthermore, as described in U.S. Pat. No. 4,123,279, a phenol having an alkyl group having 3 to 8 carbon atoms as a substituent, such as t-butylphenol formaldehyde resin and octylphenol formaldehyde resin; A condensation polymer with formaldehyde may be used in combination.

(2) Examples of the alkali-soluble polymer compound having a sulfonamide group include a polymer compound obtained by homopolymerizing a polymerizable monomer having a sulfonamide group or copolymerizing the monomer with another polymerizable monomer. . The polymerizable monomer having a sulfonamide group has at least one sulfonamide group —NH—SO _{2 in} which at least one hydrogen atom is bonded on a nitrogen atom and one polymerizable unsaturated bond in one molecule. Examples thereof include polymerizable monomers composed of low molecular compounds. Among them, a low molecular compound having an acryloyl group, an allyl group, or a vinyloxy group, and a substituted or monosubstituted aminosulfonyl group or a substituted sulfonylimino group is preferable.

(3) The alkali-soluble polymer compound having an active imide group is preferably one having an active imide group in the molecule. As the polymer compound, an unsaturated bond polymerizable with an active imide group is contained in one molecule, respectively. Examples thereof include a polymer compound obtained by homopolymerizing a polymerizable monomer composed of one or more low-molecular compounds or by copolymerizing the monomer with another polymerizable monomer.
As such a compound, specifically, N- (p-toluenesulfonyl) methacrylamide, N- (p-toluenesulfonyl) acrylamide and the like can be preferably used.

Furthermore, in addition to the above, a polymer compound obtained by polymerizing any two or more of the polymerizable monomer having a phenol group, the polymerizable monomer having a sulfonamide group, and the polymerizable monomer having an active imide group, or Also preferred are polymer compounds obtained by further copolymerizing other polymerizable monomers with these two or more polymerizable monomers.
A blending ratio (M1: M2 and M2) in which a polymerizable monomer (M2) having a sulfonamide group and / or a polymerizable monomer (M3) having an active imide group is copolymerized with the polymerizable monomer (M1) having a phenol group (Or M3; mass ratio) is preferably 50:50 to 5:95, and more preferably 40:60 to 10:90.

When the alkali-soluble polymer compound is a copolymer composed of a monomer constituent unit having any one selected from the acidic groups (1) to (3) and a constituent unit of another polymerizable monomer, The copolymer preferably contains 10 mol% or more, more preferably 20 mol% or more of a monomer structural unit having any one selected from the acidic groups (1) to (3).
From the viewpoint of obtaining sufficient alkali solubility and sufficiently widening the development latitude, it is appropriate that the content of the monomer structural unit is 10 mol% or more.
As a method for synthesizing the copolymer, conventionally known graft copolymerization method, block copolymerization method, random copolymerization method and the like can be used.

Examples of the monomer component to be copolymerized with the polymerizable monomer having a phenolic hydroxyl group, the polymerizable monomer having a sulfonamide group, or the polymerizable monomer having an active imide group include the compounds listed in the following (m1) to (m12). However, it is not limited to these.
(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, and glycidyl acrylate.
(M3) Alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, amyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, 2-chloroethyl methacrylate and glycidyl 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-ethyl- Acrylamide or methacrylamide such as 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, when the alkali-soluble polymer is a homopolymer or copolymer of a polymerizable monomer having a phenolic hydroxyl group, a polymerizable monomer having a sulfonamide group, or a polymerizable monomer having an active imide group, the weight average Those having a molecular weight of 2,000 or more and a number average molecular weight of 500 or more are preferred. 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. .
In the present invention, when the alkali-soluble polymer is a resin such as phenol formaldehyde resin or cresol aldehyde resin, the weight average molecular weight is 500 to 20,000 and the number average molecular weight is 200 to 10,000. preferable.

Further, as the alkali-soluble polymer, an alkali-soluble polymer compound having a carboxyl group (hereinafter also referred to as “component (B1)”) may be used in combination. The compound may be any alkali-soluble polymer compound having a carboxyl group, but polymer compounds (b1-1) and (b1-2) defined below are preferred.
(B1-1) An alkali-soluble polymer compound having a polymerizable monomer unit represented by the following general formula (III) (hereinafter also referred to as polymer compound (b1-1))

（式中、Ｘｍは単結合又は２価の連結基を、Ｙは水素又はカルボキシル基を、Ｚは水素、アルキル基又はカルボキシル基を表す。）
一般式（III）で表される重合性モノマー単位を構成するモノマーとして、カルボキシル基と、重合可能な不飽和基を分子内にそれぞれ１以上有する重合性モノマーがある。
そのような重合性モノマーの具体例として、アクリル酸、メタクリル酸、マレイン酸、無水マレイン酸、イタコン酸、無水イタコン酸等のα、β−不飽和カルボン酸類を挙げることができる。

(In the formula, Xm represents a single bond or a divalent linking group, Y represents hydrogen or a carboxyl group, and Z represents hydrogen, an alkyl group or a carboxyl group.)
As a monomer constituting the polymerizable monomer unit represented by the general formula (III), there is a polymerizable monomer having at least one carboxyl group and one polymerizable unsaturated group in the molecule.
Specific examples of such polymerizable monomers include α, β-unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, maleic anhydride, itaconic acid and itaconic anhydride.

Examples of the monomer to be copolymerized with the polymerizable monomer having a carboxyl group include the following (1) to (11), but are not limited thereto.
(1) Acrylic acid esters and methacrylic acid esters having an aliphatic hydroxyl group such as 2-hydroxyethyl acrylate or 2-hydroxyethyl methacrylate.
(2) Methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, amyl acrylate, hexyl acrylate, octyl acrylate, benzyl acrylate, 2-chloroethyl acrylate, glycidyl acrylate, N-dimethylaminoethyl Alkyl acrylates such as acrylates;
(3) Methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, amyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, 2-chloroethyl methacrylate, glycidyl methacrylate, N-dimethylaminoethyl Alkyl methacrylate such as methacrylate.

(4) Acrylamide, methacrylamide, N-methylolacrylamide, N-ethylacrylamide, N-hexylmethacrylamide, N-cyclohexylacrylamide, N-hydroxyethylacrylamide, N-phenylacrylamide, N-nitrophenylacrylamide, N- Acrylamide or methacrylamide such as ethyl-N-phenylacrylamide.
(5) 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.
(6) Vinyl esters such as vinyl acetate, vinyl chloroacetate, vinyl butyrate and vinyl benzoate.
(7) Styrenes such as styrene, α-methylstyrene, methylstyrene, chloromethylstyrene.

(8) Vinyl ketones such as methyl vinyl ketone, ethyl vinyl ketone, propyl vinyl ketone, and phenyl vinyl ketone.
(9) Olefins such as ethylene, propylene, isobutylene, butadiene and isoprene.
(10) N-vinylpyrrolidone, N-vinylcarbazole, 4-vinylpyridine, acrylonitrile, methacrylonitrile and the like.
(11) Unsaturated imides such as maleimide, N-acryloylacrylamide, N-acetylmethacrylamide, N-propionylmethacrylamide, N- (p-chlorobenzoyl) methacrylamide.

式中、ＸはＯ、Ｓ、又はＮ−Ｒ¹²を表す。Ｒ¹⁰〜Ｒ¹²は、各々独立に、水素原子又はアルキル基を表す。ｍ、ｎ、ｏは、各々独立に、２から５の整数を表し、Ｃ_mＨ_2m、Ｃ_nＨ_2n、Ｃ_oＨ_2oは、各々、直鎖でも分岐構造でもよい。ｐ、ｑ、ｒは各々独立に、０から３，０００の整数を表し、ｐ＋ｑ＋ｒ≧２である。 Moreover, the monomer of the following general formula (IV) is also preferably used.

In the formula, X represents O, S, or N—R ¹² . R ^{10 to} R ¹² each independently represents a hydrogen atom or an alkyl group. m, n and o each independently represents an integer of 2 to 5, and C _m H _2m , C _n H _2n and C _o H _2o may each be linear or branched. p, q, and r each independently represent an integer of 0 to 3,000, and p + q + r ≧ 2.

The alkyl group in R ¹⁰ to R ^12, preferably one having 1 to 12 carbon atoms, specifically, methyl group, ethyl group, n- propyl group, an isopropyl group. p, q, and r preferably represent an integer of 0 to 500, and more preferably represent an integer of 0 to 100.
Examples of the monomer corresponding to the repeating unit represented by the general formula (IV) are listed below, but not limited thereto.

The repeating unit represented by the general formula (IV) is a commercially available hydroxypoly (oxyalkylene) material, such as the trade name Pluronic (Pluronic (Asahi Denka Kogyo Co., Ltd.)), Adeka Polyether (Asahi Denka Kogyo Co., Ltd.). ), Carbowax (Carbowax (Glico Product)), Triton (Toriton (Rohm and Haas), and PEG (Daiichi Kogyo Seiyaku Co., Ltd.)) It can manufacture by making it react with acrylic acid, methacrylic acid, an acryl chloride, methacryl chloride, or acrylic acid anhydride by the method of this.
Separately, poly (oxyalkylene) diacrylate produced by a known method can also be used.

  Commercially available monomers include hydroxyl group-terminated polyalkylene glycol mono (meth) acrylate manufactured by Nippon Oil & Fats Co., Ltd. Blemmer PE-90, Blemmer PE-200, Blemmer PE-350, Blemmer AE-90, Blemmer AE-200, Blemmer AE-400, Blemmer PP-1000, Blemmer PP-500, Blemmer PP-800, Blemmer AP-150, Blemmer AP-400, Blemmer AP-550, Blemmer AP-800, Blemmer 50PEP-300, Blemmer 70PEP-350B, Blemmer AEP series, Blemmer 55PET-400, Blemmer 30PET-800, Blemmer 55PET-800, Blemmer AET series, Blemmer 30PPT-800, Blemmer 50PPT-800, Blemmer 70PPT-800, Blemmer APT series, Blemmer 10PPB-500B, Blemmer 10APB-500B Etc. Similarly, Blemmer PME-100, Blemmer PME-200, Blemmer PME-400, Blemmer PME-1000, Blemmer PME-4000, Blemmer AME-400, Blemmer as alkyl-terminated polyalkylene glycol mono (meth) acrylates manufactured by NOF Corporation 50POEP-800B, Blemmer 50AOEP-800B, Blemmer PLE-200, Blemmer ALE-200, Blemmer ALE-800, Blemmer PSE-400, Blemmer PSE-1300, Blemmer ASEP series, Blemmer PKEP series, Blemmer AKEP series, Blemmer ANE-300 , BLEMMER ANE-1300, BLEMMER PNEP series, BLEMMER PNPE series, BLEMMER 43ANEP-500, BLEMMER 70ANEP-550, etc., and Kyoeisha Chemical Co., Ltd. Acrylate EC-A, Light acrylate MTG-A, Light acrylic Over DOO 130A, Light Acrylate DPM-A, Light Acrylate P-200A, Light Acrylate NP-4EA, like Light Acrylate NP-8EA.

The minimum constitutional unit having a polymerizable monomer component having at least one carboxyl group and at least one polymerizable unsaturated group in the polymer compound (b1-1) does not have to be one kind in particular, and is the same. It is also possible to use a copolymer obtained by copolymerizing two or more kinds of minimum structural units having the above acidic group or two or more kinds of minimum structural units having different acidic groups.
As the copolymerization method, conventionally known graft copolymerization, block copolymerization, random copolymerization, and the like can be used.

(B1-2) A reaction product of a diol compound represented by the following general formula (V), (VI) or (VII) having a carboxyl group and a diisocyanate compound represented by the following general formula (X) as a basic skeleton And an alkali-soluble polymer compound having a carboxyl group (hereinafter, also referred to as polymer compound (b1-2)).

R ¹³ is a hydrogen atom, an alkyl, alkenyl, aralkyl, aryl, alkoxy, aryloxy which may have a hydrogen atom, a substituent (eg, alkyl, aryl, alkoxy, ester, urethane, amide, ureido, halogeno). Preferably a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an alkenyl group having 2 to 8 carbon atoms, or an aryl group having 6 to 15 carbon atoms.
R ¹⁴ , R ¹⁵ and R ¹⁶ may have the same or different single bond and substituent (for example, alkyl, alkenyl, aralkyl, aryl, alkoxy and halogeno groups are preferred). Or a divalent aliphatic or aromatic hydrocarbon. Preferably an alkylene group having 1 to 20 carbon atoms, an arylene group having 6 to 15 carbon atoms, and more preferably an alkylene group having 1 to 8 carbon atoms is shown.
If necessary, R ¹⁴ , R ¹⁵ and R ¹⁶ have other functional groups that do not react with isocyanate groups, such as ester groups, urethane groups, amide groups, ureido groups, and carbon-carbon unsaturated bonds. Also good. In addition, you may comprise a ring by 2 or 3 of R < ¹³ >, R <^14> , R <^15> , R < ¹⁶ >.
Ar represents a trivalent aromatic hydrocarbon which may have a substituent, and preferably an aromatic group having 6 to 15 carbon atoms.

OCN-R ¹⁸ -NCO (X)
In the formula, R ¹⁸ represents a divalent aliphatic or aromatic hydrocarbon which may have a substituent (eg, alkyl, alkenyl, aralkyl, aryl, alkoxy and halogeno groups are preferred). If necessary, R ¹⁸ may have another functional group that does not react with an isocyanate group, for example, an ester, a urethane, an amide, a ureido group, or a carbon-carbon unsaturated bond.

Specific examples of the diol compound having a carboxyl group represented by the general formula (V), (VI) or (VII) include those shown below.
3,5-dihydroxybenzoic acid, 2,2-bis (hydroxymethyl) propionic acid, 2,2-bis (2-hydroxyethyl) propionic acid, 2,2-bis (3-hydroxypropyl) propionic acid, Bis (hydroxymethyl) acetic acid, bis (4-hydroxyphenyl) acetic acid, 4,4-bis (4-hydroxyphenyl) pentanoic acid, tartaric acid, N, N-bis (2-hydroxyethyl) -3-carboxy-propionamide Etc.

式中、Ｒ¹⁷はそれぞれ水素原子又は炭素原子数１〜８のアルキル基を示し、ｎは２以上の整数を示す。Ｒ¹⁷における炭素原子数１〜８のアルキル基としては、例えばメチル基、エチル基、i-プロピル基、n-ブチル基、i-ブチル基などが挙げられる。
以下に、上記一般式（VIII）又は（IX）で表されるジオールの具体例を示すが、本発明はこれらに限定されるものではない。 The alkali-soluble polymer compound having a carboxyl group (b1-2) is preferably a reaction product in which a diol represented by the following general formula (VIII) or (IX) is combined.

In the formula, R ¹⁷ represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and n represents an integer of 2 or more. Examples of the alkyl group having 1 to 8 carbon atoms in R ¹⁷ include a methyl group, an ethyl group, an i-propyl group, an n-butyl group, and an i-butyl group.
Specific examples of the diol represented by the general formula (VIII) or (IX) are shown below, but the present invention is not limited thereto.

Specific example of (VIII)
HO-(-CH ₂ CH ₂ O-) ₃ -H
HO-(-CH ₂ CH ₂ O-) ₄ -H
HO-(-CH ₂ CH ₂ O-) ₅ -H
HO-(-CH ₂ CH ₂ O-) ₆ -H
HO-(-CH ₂ CH ₂ O-) ₇ -H
HO-(-CH ₂ CH ₂ O-) ₈ -H
HO-(-CH ₂ CH ₂ O-) ₁₀ -H
HO-(-CH ₂ CH ₂ O-) ₁₂ -H
Polyethylene glycol (average molecular weight 1000)
Polyethylene glycol (average molecular weight 2000)
Polyethylene glycol (average molecular weight 4000)
HO-(-CH ₂ CH (CH ₃ ) O-) ₃ -H
HO-(-CH ₂ CH (CH ₃ ) O-) ₄ -H
HO-(-CH ₂ CH (CH ₃ ) O-) ₆ -H
Polypropylene glycol (average molecular weight 1000)
Polypropylene glycol (average molecular weight 2000)
Polypropylene glycol (average molecular weight 4000)

Specific example of (IX)
HO-(-CH ₂ CH ₂ CH ₂ O-) ₃ -H
HO-(-CH ₂ CH ₂ CH ₂ O-) ₄ -H
HO-(-CH ₂ CH ₂ CH ₂ O-) ₈ -H
HO-(-CH ₂ CH ₂ CH (CH ₃ ) O-) ₁₂ -H

Specific examples of the diisocyanate compound represented by the general formula (X) include those shown below.
That is, 2,4-tolylene diisocyanate, dimer of 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, p-xylylene diisocyanate, m-xylylene diisocyanate, 4,4′-diphenylmethane diisocyanate, Aromatic diisocyanate compounds such as 1,5-naphthalene diisocyanate and 3,3′-dimethylbiphenyl-4,4′-diisocyanate; aliphatic diisocyanates such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, lysine diisocyanate and dimer acid diisocyanate Compound, isophorone diisocyanate, 4,4′-methylenebis (cyclohexyl isocyanate), methylcyclohexane-2,4 (or 2,6) -diisocyanate, 1 An aliphatic diisocyanate compound such as 1,3- (isocyanatomethyl) cyclohexane; a diisocyanate compound which is a reaction product of a diol and diisocyanate such as an adduct of 1 mol of 1,3-butylene glycol and 2 mol of tolylene diisocyanate, and the like. Can be mentioned.

  The molar ratio of the diisocyanate and the diol compound used for the synthesis of the polymer compound (b1-2) is preferably 0.8: 1 to 1.2-1, and when an isocyanate group remains at the polymer terminal, alcohols or By treating with amines or the like, it is finally synthesized in a form in which no isocyanate group remains.

As the component (B1), one type may be used alone from the above polymer compounds (b1-1) and (b1-2), or two or more types may be used in combination.
The content of the repeating unit having a carboxyl group contained in the component (B1) is 2 mol% or more based on the total amount of each monomer of the component (B1), preferably 2 to 70 mol%. Yes, more preferably in the range of 5 to 60 mol%.
The preferred weight average molecular weight of the component (B1) is preferably 3000 to 300,000, more preferably 6,000 to 100,000.

From the viewpoint of durability and sensitivity of the image forming layer, the content of the alkali-soluble resin in the image forming layer is suitably 30 to 99% by mass, preferably 40 to 40%, based on the total solid content of the image forming layer. It is 95 mass%, More preferably, it is 50-90 mass%.
When the component (B1) is included, it is in the range of 0.005 to 80% by mass, preferably in the range of 0.01 to 50% by mass, and more preferably, relative to the total solid mass of the image forming layer. It is the range of 1-20 mass%.

When the image forming layer has a laminated structure, the above-mentioned alkali-soluble polymer can be used alone or in combination of two or more in the upper image forming layer. In particular, in the upper image forming layer, a resin having a phenolic hydroxyl group is desirable in that strong hydrogen bonding occurs in the unexposed area, and part of the hydrogen bonding is easily released in the exposed area, and more preferably novolak. Resin.
As the alkali-soluble polymer used in the lower layer, the above-described alkali-soluble polymers can be used alone or in combination of two or more. Of these, acrylic resins are preferred. Furthermore, those having a sulfoamide group are particularly preferred as the acrylic resin, and such resins may be used alone or in combination of two or more.
The lower layer may be substantially composed of an alkali-soluble polymer.

  The alkali-soluble polymer compound in the upper image forming layer is suitably used in an addition amount of 50 to 90% by mass from the viewpoints of both sensitivity and durability. Moreover, the mixing ratio of two types of alkali-soluble polymer compounds having different dissolution rates with respect to the alkaline aqueous solution is arbitrary. Preferably, in the alkali-soluble polymer compound, an alkali-soluble polymer compound having a phenolic hydroxyl group that causes strong hydrogen bondability in the unexposed area and easily releases some hydrogen bonds in the exposed area is 60 to 99.99. Used at 8% by weight. In this range, the image formability is sufficiently good.

[Infrared absorbing dye]
The infrared absorbing dye used in the image forming layer is not particularly limited as long as it absorbs infrared rays and generates heat, and various dyes known as infrared absorbing dyes can be used.
As the infrared absorbing dye, commercially available dyes and known dyes described in the literature (for example, “Dye Handbook” edited by the Society of Synthetic Organic Chemistry, published in 1970) can be used. Specific examples include azo dyes, metal complex azo dyes, pyrazolone azo dyes, quinoneimine dyes, methine dyes, and cyanine dyes. In the present invention, among these dyes, those that absorb infrared light or near infrared light are particularly preferred because they are suitable for use in lasers that emit infrared light or near infrared light.
Examples of dyes that absorb such infrared light or near infrared light include, for example, JP-A-58-125246, JP-A-59-84356, JP-A-59-202829, and JP-A-60-78787. Methine dyes described in JP-A-58-173696, JP-A-58-181690, JP-A-58-194595, etc., JP-A-58-112793, Naphthoquinone dyes described in JP-A-58-224793, JP-A-59-48187, JP-A-59-73996, JP-A-60-59240, JP-A-60-63744, etc. Examples thereof include squarylium dyes described in JP-A-58-112792, and cyanine dyes described in British Patent 434,875.

Further, a near-infrared absorption sensitizer described in US Pat. No. 5,156,938 is also preferably used as the dye, 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 Pentamethine thiopyrylium salts described in No. 5 and pyrylium compounds disclosed in Japanese Patent Publication Nos. 5-13514 and 5-19702 But as the commercially available products, Eporin Co. EpolightIII-178, Epolight III-130, Epolight III-125 and the like are particularly preferably used.
Infrared absorbing dyes described as formulas (I) and (II) in US Pat. No. 4,756,993 are particularly preferred as infrared absorbing dyes used in the image forming layer. The dye exhibits a very strong interaction with the alkalinized soluble resin, and is excellent in the unexposed area alkaline development resistance of the image forming layer.

Specific examples of the infrared absorbing dye are shown below, but the present invention is not limited thereto.

The content of the infrared absorbing dye in the image forming layer is 0.01 to 50 with respect to the total solid mass of the image forming layer from the viewpoint of maintaining good sensitivity and uniformity of the image forming layer and improving durability. % By mass is preferable, 0.1 to 30% by mass is more preferable, and further 0.5 to 10% by mass is preferable.
The infrared absorbing dye may be added to the same layer as the other components, or a separate layer may be provided and added thereto.

When the image forming layer has a laminated structure, these infrared absorbing dyes can be added not only to the upper image forming layer but also to the lower layer. By adding an infrared absorbing dye to the lower layer, the lower layer can also function as a heat-sensitive layer. When an infrared absorbing dye is added to the lower layer, the same materials as those in the upper image forming layer may be used, or different materials may be used.
In addition, these infrared absorbing dyes may be added to the same layer as other components, or may be added to another layer provided. In the case of a separate layer, it is desirable to add it to a layer adjacent to the image forming layer. The dye and the alkali-soluble resin are preferably contained in the same layer, but may be in different layers.
As the amount added, in the case of the upper image forming layer, 0.01 to 50% by mass, preferably from the total solid content of the layer, from the viewpoint of maintaining good sensitivity and uniformity of the upper image forming layer and improving the durability. Can be added to the printing plate material in a proportion of 0.1 to 30% by mass, particularly preferably 1.0 to 30% by mass.

  In the case of the lower layer, it can be added to the printing plate material in a proportion of 0 to 20% by mass, preferably 0 to 10% by mass, particularly preferably 0 to 5% by mass with respect to the total solid content of the lower layer. When the infrared absorbing dye is added to the lower layer, the solubility of the lower layer is lowered, but by adding the infrared absorbing dye, the solubility of the lower layer can be expected to be improved by heat during exposure. However, in the region of 0.2 to 0.3 μm in the vicinity of the support, solubility improvement due to heat does not occur at the time of exposure, and the lowering of the solubility of the lower layer due to the addition of an infrared absorbing dye causes a decrease in sensitivity. Therefore, even in the range of the addition amount shown above, an addition amount in which the dissolution rate of the lower layer is less than 30 nm is not preferable.

[Other additives]
In forming the image forming layer, in addition to the above essential components, various additives can be further added as necessary as long as the effects of the present invention are not impaired.
When the image forming layer has a laminated structure, the additive may be contained only in the lower layer, may be contained only in the upper image forming layer, or may be contained in both layers.
Below, the example of an additive is given and demonstrated.

-Solubility-inhibiting compounds-
The infrared-sensitive lithographic printing plate precursor can contain various inhibitors in the image forming layer for the purpose of enhancing its inhibition (solubility inhibition).
Although it does not specifically limit as this inhibitor, A quaternary ammonium salt, a polyethyleneglycol type compound, etc. are mentioned.

The quaternary ammonium salt is not particularly limited, and examples thereof include tetraalkylammonium salts, trialkylarylammonium salts, dialkyldiarylammonium salts, alkyltriarylammonium salts, tetraarylammonium salts, cyclic ammonium salts, and bicyclic ammonium salts. .
Specifically, tetrabutylammonium bromide, tetrapentylammonium bromide, tetrahexylammonium bromide, tetraoctylammonium bromide, tetralaurylammonium bromide, tetraphenylammonium bromide, tetranaphthylammonium bromide, tetrabutylammonium chloride, tetrabutylammonium iodide , Tetrastearyl ammonium bromide, lauryl trimethyl ammonium bromide, stearyl trimethyl ammonium bromide, behenyl trimethyl ammonium bromide, lauryl triethyl ammonium bromide, phenyl trimethyl ammonium bromide, 3-trifluoromethylphenyl trimethyl ammonium bromide, benzyl trimethyl ammonium bromide De, dibenzyl dimethyl ammonium bromide, distearyl dimethyl ammonium bromide, tristearyl methyl ammonium bromide, benzyl triethyl ammonium bromide, hydroxyphenyl trimethyl ammonium bromide, N- methyl pyridinium bromide, and the like. In particular, quaternary ammonium salts described in Japanese Patent Application Nos. 2001-226297, 2001-370059, and 2001-398047 are preferable.

  The addition amount of the quaternary ammonium salt is 0.1% in terms of solid content with respect to the total solid content mass of the image forming layer from the viewpoint of sufficiently exerting its solubility inhibiting effect and not adversely affecting the film forming property of the binder. It is preferable that it is 1-50 mass%, and it is more preferable that it is 1-30 mass%.

Although it does not specifically limit as a polyethyleneglycol compound, The thing of the following structure is mentioned.
^{R 1 - {- O- (R} 3 -O-) m-R 2} n
(R ¹ is a polyhydric alcohol residue or polyhydric phenol residue, R ² is a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an alkylyl group, an aryl group or an aryloyl group which may have a C1-25 substituent. Group R ³ represents an alkylene residue which may have a substituent, m is an average of 10 or more, and n is an integer of 1 to 4.

  Examples of polyethylene glycol compounds having the above structure include polyethylene glycols, polypropylene glycols, polyethylene glycol alkyl ethers, polypropylene glycol alkyl ethers, polyethylene glycol aryl ethers, polypropylene glycol aryl ethers, polyethylene glycol alkyl aryl ethers, Polypropylene glycol alkyl aryl ethers, polyethylene glycol glycerol esters, polypropylene glycol glycerol esters, polyethylene sorbitol esters, polypropylene glycol sorbitol esters, polyethylene glycol fatty acid esters, polypropylene glycol fatty acid esters, polyethylene glycolated ethylene Amines, polypropylene glycolated ethylenediamines, polyethylene glycolated diethylenetriamine, and polypropylene glycol diethylenetriamines.

  Specific examples thereof include polyethylene glycol 1000, polyethylene glycol 2000, polyethylene glycol 4000, polyethylene glycol 10000, polyethylene glycol 20000, polyethylene glycol 50000, polyethylene glycol 100000, polyethylene glycol 200000, polyethylene glycol 500000, polypropylene glycol 1500, polypropylene glycol. 3000, polypropylene glycol 4000, polyethylene glycol methyl ether, polyethylene glycol ethyl ether, polyethylene glycol phenyl ether, polyethylene glycol dimethyl ether, polyethylene glycol diethyl ether, polyethylene glycol diphenyl ether , Polyethylene glycol lauryl ether, polyethylene glycol dilauryl ether, polyethylene glycol nonyl ether, polyethylene glycol cetyl ether, polyethylene glycol stearyl ether, polyethylene glycol distearyl ether, polyethylene glycol behenyl ether, polyethylene glycol dibehenyl ether, polypropylene glycol methyl ether, polypropylene Glycol ethyl ether, polypropylene glycol phenyl ether, polypropylene glycol dimethyl ether, polypropylene glycol diethyl ether, polypropylene glycol diphenyl ether, polypropylene glycol lauryl ether, polypropylene glycol dilauryl ether, Ripropylene glycol nonyl ether, polyethylene glycol acetyl ester, polyethylene glycol diacetyl ester, polyethylene glycol benzoic acid ester, polyethylene glycol lauryl ester, polyethylene glycol dilauryl ester, polyethylene glycol nonyl acid ester, polyethylene glycol cetyl acid ester, polyethylene glycol stearoyl ester, Polyethylene glycol distearoyl ester, polyethylene glycol behenate ester, polyethylene glycol dibehenate ester, polypropylene glycol acetyl ester, polypropylene glycol diacetyl ester, polypropylene glycol benzoate ester, polypropylene glycol dibenzoate ester, Polypropylene glycol laurate, polypropylene glycol dilaurate, polypropylene glycol nonyl ester, polyethylene glycol glycerol ether, polypropylene glycol glycerol ether, polyethylene glycol sorbitol ether, polypropylene glycol sorbitol ether, polyethylene glycolated ethylenediamine, polypropylene glycolated ethylenediamine, polyethylene Examples include glycolated diethylenetriamine, polypropylene glycolated diethylenetriamine, and polyethylene glycolated pentamethylenehexamine.

  The addition amount of the polyethylene glycol-based compound is 0.1 to 0.1 in terms of solid content with respect to the total solid content mass of the image forming layer from the viewpoint of sufficiently exhibiting its solubility inhibiting effect and not adversely affecting image forming properties. It is preferable that it is 50 mass%, and it is more preferable that it is 1-30 mass%.

Further, when the above-described measures for improving the inhibition (solubility inhibition) are performed, the sensitivity is lowered. In this case, it is effective to add a lactone compound. It is considered that the lactone compound reacts with the developer and the lactone compound when the developer penetrates into the exposed area, and a new carboxylic acid compound is generated, contributing to dissolution of the exposed area and improving sensitivity.
Although it does not specifically limit as a lactone compound, The compound represented by the following general formula (LI) and general formula (L-II) is mentioned.

In the general formula (LI) and general formula (L-II), X ¹ , X ² , X ³ and X ⁴ are ring constituent atoms or atomic groups, which may be the same or different, and are independent of each other. And may have a substituent, and at least one of X ¹ , X ² and X ³ in formula (LI) and X ¹ , X ² , X ³ and X in formula (L-II) ^At least one of ⁴ has an electron-withdrawing substituent or a substituent substituted with an electron-withdrawing group.
The constituent atoms or atomic groups of the ring represented by X ¹ , X ² , X ³ and X ⁴ are nonmetallic atoms having two single bonds for forming a ring or atomic groups containing the nonmetallic atoms.
A preferred nonmetallic atom or nonmetallic atomic group is an atom or atomic group selected from a methylene group, a sulfinyl group, a carbonyl group, a thiocarbonyl group, a sulfonyl group, a sulfur atom, an oxygen atom, and a selenium atom, and more preferably, It is an atomic group selected from a methylene group, a carbonyl group and a sulfonyl group.

At least one of X ¹ , X ² and X ^{3 in} the general formula (LI) or at least one of X ¹ , X ² , X ³ and X ^{4 in} the general formula (L-II) is an electron withdrawing group Have In the present specification, an electron-withdrawing substituent refers to a group in which Hammett's substituent constant σp takes a positive value. Regarding the Hammett's substituent constant, Journal of Medicinal Chemistry, 1973, Vol. 16, No. 11, 1207-1216, etc. can be referred to. Examples of electron-withdrawing groups in which Hammett's substituent constant σp takes a positive valence include halogen atoms (fluorine atoms (σp value: 0.06), chlorine atoms (σp value: 0.23), bromine atoms (σp value). : 0.23), iodine atom (σp value: 0.18)), trihaloalkyl group (tribromomethyl (σp value: 0.29), trichloromethyl (σp value: 0.33), trifluoromethyl (σp) Value: 0.54)), cyano group (σp value: 0.66), nitro group (σp value: 0.78), aliphatic / aryl or heterocyclic sulfonyl group (for example, methanesulfonyl (σp value: 0. 72)), aliphatic / aryl or heterocyclic acyl groups (for example, acetyl (σp value: 0.50), benzoyl (σp value: 0.43)), alkynyl groups (for example, C≡CH (σp value: 0)) .23)), Aliphatic Ali Or a heterocyclic oxycarbonyl group (for example, methoxycarbonyl (σp value: 0.45), phenoxycarbonyl (σp value: 0.44)), carbamoyl group (σp value: 0.36), sulfamoyl group (σp value: 0.57), sulfoxide groups, heterocyclic groups, oxo groups, phosphoryl groups and the like.

Preferred electron withdrawing groups are amide groups, azo groups, nitro groups, fluoroalkyl groups having 1 to 5 carbon atoms, nitrile groups, alkoxycarbonyl groups having 1 to 5 carbon atoms, acyl groups having 1 to 5 carbon atoms, and carbon numbers. An alkylsulfonyl group having 1 to 9 carbon atoms, an arylsulfonyl group having 6 to 9 carbon atoms, an alkylsulfinyl group having 1 to 9 carbon atoms, an arylsulfinyl group having 6 to 9 carbon atoms, an arylcarbonyl group having 6 to 9 carbon atoms, and thiocarbonyl A group selected from a group, a fluorine-containing alkyl group having 1 to 9 carbon atoms, a fluorine-containing aryl group having 6 to 9 carbon atoms, a fluorine-containing allyl group having 3 to 9 carbon atoms, an oxo group, and a halogen element.
More preferably, a nitro group, a fluoroalkyl group having 1 to 5 carbon atoms, a nitrile group, an alkoxycarbonyl group having 1 to 5 carbon atoms, an acyl group having 1 to 5 carbon atoms, an arylsulfonyl group having 6 to 9 carbon atoms, carbon It is a group selected from an arylcarbonyl group of formulas 6 to 9, an oxo group and a halogen element.
Specific examples of the compounds represented by general formula (LI) and general formula (L-II) are shown below, but the present invention is not limited to these compounds.

The amount of the compound represented by the general formula (LI) and the general formula (L-II) is such that the effects of these compounds can be sufficiently exerted and the image-forming property can be improved. The solid content is preferably 0.1 to 50% by mass and more preferably 1 to 30% by mass with respect to the solid content. In addition, since this compound reacts with a developing solution, it is desirable to contact a developing solution selectively.
These lactone compounds may be used alone or in combination. Two or more compounds of the general formula (LI) or two or more compounds of the general formula (L-II) may be used in an arbitrary ratio within the above range.

  In addition, a substance that is thermally decomposable, such as an onium salt, an o-quinonediazide compound, an aromatic sulfone compound, and an aromatic sulfonic acid ester compound, and that substantially reduces the solubility of the alkaline water-soluble polymer compound without being decomposed. Use in combination is preferable in terms of improving the dissolution inhibition of the image area in the developer. Examples of onium salts include diazonium salts, ammonium salts, phosphonium salts, iodonium salts, sulfonium salts, selenonium salts, and arsonium salts.

Preferred examples of the onium salt used in the present invention include SI Schlesinger, Photogr. Sci. Eng., 18, 387 (1974), TS Bal et al, Polymer, 21, 423 (1980), No. 158230, U.S. Pat.Nos. 4,069,055 and 4,069,056, ammonium salts described in JP-A-3-140140, DC Necker et al, Macromorecules, 17, 2468 (1984), CS Wen et al, Teh, Proc. Conf. Rad. Curing ASIA, p478 Tokyo, Oct (1988), U.S. Pat.Nos. 4,069,055 and 4,069,056. (1977), Chem. & Eng. News, Nov. 28, p31 (1988), European Patent No. 104,143, U.S. Pat.Nos. 339,049, 410,201, JP-A-2-150848, JP-A-2-96514 JVCrivello et al, Polymer J. 17, 73 (1985), JV Crivello et al. J. Org. Chem., 43, 3055 (1978), WR Watt et al, J. Polymer Sci., Polymer Chem. Ed., 22, 1789 (1984), JV Crivello et al, Polymer Bull., 14, 279 (1985), JV Crivello et al, Macromorecules, 14 (5), 1141 (1981), JV Crivello et al, J. Polymer Sci. , Polymer Chem. Ed., 17, 2877 (1979), European Patents 370,693, 233,567, 297,443, 297,442, U.S. Patents 4,933,377, 3,902,114, 410,201, 339,049, 4,760,013, 4,734,444, 2,833,827, German Patent Nos. 2,904,626, 3,604,580, 3,604,581 Selenonium salt described in Crivello et al, J. Polymer Sci., Polymer Chem. Ed., 17, 1047 (1979), CS Wen et al, Teh, Proc. Conf. Rad. Curing ASIA, p.478 Tokyo, Oct (1988) and the like.
Of the 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 -Sulphonic acid, 2-methoxy-4-hydroxy-5-benzoyl-benzenesulfonic acid, p-toluenesulfonic acid and the like can be mentioned. 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 assists the solubility of the sensitive material system by both the effect of losing the inhibition of dissolution of the binder by 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 compounds described in pages 339 to 352 of “Light-Sensitive Systems” by Korser can be used, they are particularly reacted with various aromatic polyhydroxy compounds or aromatic amino compounds. -Sulfonic acid esters or sulfonic acid amides of quinonediazides 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, benzoquinone- (1,2-diazide sulfonic acid chloride or naphthoquinone- (1,2) -diazide-5 sulfonic acid chloride and phenol-formaldehyde resins described in US Pat. Nos. 3,046,120 and 3,188,210 Esters are also preferably used.

  Further, an ester of naphthoquinone- (1,2) -diazido-4-sulfonic acid chloride and 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 47-5303, JP 48-63802, JP 48-63803, JP 48-96575, JP 49-38701, JP 48-13354, No. 41-11222, No. 45-9610, No. 49-17481, U.S. Patent No. 2,797,213, No. 3,454,400, No. 3,544,323, No. 3,573,917, No. 3,674,495, No. 3,785,825 And British Patents 1,227,602, 1,251,345, 1,267,005, 1,329,888, 1,330,932, German Patent 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 mass of the image forming layer. These compounds can be used alone, but may be used as a mixture of several kinds.

Further, for the purpose of enhancing the dissolution inhibiting property on the surface of the image forming layer and enhancing the resistance to scratches on the surface, as described in JP-A No. 2000-187318, the number of carbon atoms in the molecule is 3 to 20 carbon atoms. It is preferable to use a polymer having a polymerization component of a (meth) acrylate monomer having 2 or 3 fluoroalkyl groups.
As addition amount, the ratio for which it occupies in the material of a layer is 0.1-10 mass%, More preferably, it is 0.5-5 mass%.

-Development accelerator-
For the purpose of further improving sensitivity, acid anhydrides, phenols and organic acids can be used in combination.
Cyclic acid anhydrides are preferred as the acid anhydrides, and specific examples of cyclic acid anhydrides include phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride described in US Pat. No. 4,115,128, 6-Endoxy-tetrahydrophthalic anhydride, tetrachlorophthalic anhydride, maleic anhydride, chloromaleic anhydride, α-phenylmaleic anhydride, succinic anhydride, pyromellitic anhydride and the like can be used. Examples of the acyclic acid anhydride include acetic anhydride. The phenols include bisphenol A, 2,2′-bishydroxysulfone, p-nitrophenol, p-ethoxyphenol, 2,4,4′-trihydroxybenzophenone, 2,3,4-trihydroxybenzophenone, 4- Examples include hydroxybenzophenone, 4,4 ', 4 "-trihydroxytriphenylmethane, 4,4', 3", 4 "-tetrahydroxy-3,5,3 ', 5'-tetramethyltriphenylmethane. .

Furthermore, examples of organic acids include sulfonic acids, sulfinic acids, alkyl sulfates, 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, Examples include 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 image forming layer is preferably 0.05 to 20% by mass, more preferably 0.1 to 15% by mass, and particularly preferably 0.1 to 10%. % By mass.

-Surfactant-
In order to improve the coatability of the image forming layer and to expand the stability of the processing with respect to the development conditions, non-disclosures such as those described in JP-A-62-251740 and JP-A-3-208514 are described. Ionic surfactants, amphoteric surfactants as described in JP-A-59-121044, JP-A-4-13149, siloxane compounds as described in EP950517, JP-A-62 A fluorine-containing monomer copolymer as described in JP-A-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, polyoxyethylene nonylphenyl ether and the like. Specific examples of amphoteric surfactants include alkyldi (aminoethyl) glycine, alkylpolyaminoethylglycine hydrochloride, 2-alkyl-N-carboxyethyl-N-hydroxyethylimidazolinium betaine and N-tetradecyl-N, N- Examples include 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-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 image forming layer is preferably from 0.01 to 15% by mass, more preferably from 0.1 to 5% by mass, and even more preferably from 0.05 to 0. 0.5% by mass.

[Bake-out agent / colorant]
In the image forming layer of the infrared-sensitive positive lithographic printing plate used in the present invention, a printing agent for obtaining a visible image immediately after heating by exposure, or a dye or pigment as an image colorant may be added. it can.
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-based compounds and triazine-based 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 above-mentioned 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 image forming layer.

[Plasticizer]
Furthermore, a plasticizer is added to the image forming layer of the infrared-sensitive lithographic printing plate precursor used in the present invention, if necessary, 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.

[Wax agent]
In addition, the image forming layer of the infrared-sensitive lithographic printing plate precursor may contain a compound that lowers the surface static friction coefficient for the purpose of imparting resistance to scratches. Specifically, long-chain alkyl carboxylic acids such as those used in US Pat. No. 6,117,913, JP-A No. 2003-149799, JP-A No. 2003-302750, and JP-A No. 2004-012770 are used. Examples include compounds having an ester.
The addition amount is preferably 0.1 to 10% by mass, more preferably 0.5 to 5% by mass in the material forming the image forming layer.

The image forming layer of the infrared-sensitive lithographic printing plate precursor can be usually formed by dissolving the above-described components in a solvent and coating the solution on a suitable support.
Solvents used here include ethylene dichloride, cyclohexanone, methyl ethyl ketone, methanol, ethanol, propanol, ethylene glycol monomethyl ether, 1-methoxy-2-propanol, 2-methoxyethyl acetate, 1-methoxy-2-propyl acetate, dimethoxy Examples include ethane, methyl lactate, ethyl lactate, N, N-dimethylacetamide, N, N-dimethylformamide, tetramethylurea, N-methylpyrrolidone, dimethyl sulfoxide, sulfolane, γ-butyrolactone, and toluene. It is not limited. These solvents are used alone or in combination.

When the image forming layer has a laminated structure, as a solvent used for coating, in principle, a solvent having different solubility for the alkali-soluble polymer used for the upper image-forming layer and the alkali-soluble polymer used for the lower layer should be selected. However, it is also possible to actively carry out partial compatibility in order to impart a new function.
Examples of the method for forming the two layers separately include, for example, a method using a difference in solvent solubility between the copolymer contained in the lower layer and the alkali-soluble resin contained in the upper image forming layer, and the upper image forming layer. And a method of rapidly drying and removing the solvent after coating. Hereinafter, although these methods are explained in full detail, the method of isolate | separating and apply | coating two layers is not limited to these.

  The method using the difference in solvent solubility between the copolymer contained in the lower layer and the alkaline aqueous solution-soluble resin contained in the upper image forming layer is the specific copolymer contained in the lower layer when the alkaline aqueous solution-soluble resin is applied. In addition, any of the copolymers used in combination with the solvent system is insoluble. Thereby, even if it carries out 2 layer application | coating, it becomes possible to isolate | separate each layer clearly and to make a coating film. For example, a copolymer containing a specific monomer constituting a lower layer component insoluble in a solvent that dissolves an alkaline aqueous solution such as methyl ethyl ketone or 1-methoxy-2-propanol is selected as the copolymer component, and the lower layer component is constituted. The lower layer mainly composed of the copolymer is applied and dried using a solvent system that dissolves the copolymer, and then the upper image forming layer mainly composed of the aqueous alkali solution-soluble resin is coated with methyl ethyl ketone, 1-methoxy-2-propanol, etc. Two layers can be formed by coating using a solvent that does not dissolve the lower layer components.

On the other hand, the method of drying the solvent very quickly after the second layer is applied is that high-pressure air is blown from a slit nozzle installed almost perpendicular to the running direction of the web or a heating medium such as steam is supplied to the inside. This can be achieved by applying thermal energy as conduction heat from the lower surface of the web from a heated roll (heating roll), or by combining them.
As a method of partially compatibility between the two layers at a level where the effects of the present invention are sufficiently exhibited, a method using the above-mentioned difference in solvent solubility, and drying the solvent very quickly after the second layer is applied In any method, it is possible by adjusting the degree.

The coating solution applied to the support for forming the image forming layer is used by dissolving these components in a suitable solvent. The concentration of the above components (total solid content including additives) in the solvent is preferably 1 to 50% by mass. Various methods can be used as the coating method, and examples thereof include bar coater coating, spin coating, spray coating, curtain coating, dip coating, air knife coating, blade coating, and roll coating.
When the image forming layer has a laminated structure, the upper image forming layer is preferably applied in a non-contact manner in order to prevent damage to the lower layer when the upper image forming layer is applied. Although it is a contact type, it is possible to use bar coater coating as a method generally used for solvent-based coating, but it is desirable to apply by forward driving in order to prevent damage to the lower layer.

The dry coating amount (solid content) of the image forming layer provided by coating and drying on the support is generally 0.5 to 5.0 g / m ² .
When the image forming layer has a laminated structure, the lower layer is preferably in the range of 0.5 to 4.0 g / m ² and more preferably 0.6 from the viewpoint of printing durability, image reproducibility and sensitivity. It is in the range of ˜2.5 g / m ² . The upper image-forming layer, development latitude, from the viewpoint of scratch resistance is preferably in the range of ^{0.05g / m 2 ~1.0g / m 2} , more preferably 0.08 to 0.7 g / m ² Range. The coating amount of the combined upper and lower layers, from the viewpoint of good printing durability and good image reproducibility and sensitivity, is preferably in the range of ^{0.6g / m 2 ~4.0g / m 2} , more preferably Is in the range of 0.7 to 2.5 g / m ² .

[Support]
Examples of the hydrophilic support used in the infrared-sensitive lithographic printing plate precursor include a dimensionally stable plate having necessary strength and durability. For example, paper, plastic (for example, polyethylene, Paper laminated with 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.), paper laminated with metal as described above, or vapor-deposited paper, or plastic film.

  As the support, a polyester film or an aluminum plate is preferable. 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 foreign 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.

  A particularly suitable aluminum is pure aluminum, but completely pure aluminum is difficult to manufacture in terms of refining technology, and may contain slightly foreign elements. Thus, the composition of the aluminum plate is not specified, and an aluminum plate made of a publicly known material can be used as appropriate. 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.

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 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 JP-A-54-63902, a method in which both are combined can also be used.
The roughened aluminum plate is subjected to an alkali etching treatment and neutralization treatment as necessary, and then subjected to an anodization treatment to enhance the water retention and wear resistance of the surface as desired. 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. The amount of the anodic oxide film is sufficient in terms of printing durability, prevents scratches on the non-image area of the lithographic printing plate, and prevents so-called “scratch stains” where ink adheres to the scratch area during printing. 1.0 g / m ² or more is appropriate.
After the anodizing treatment, the aluminum surface is subjected to a hydrophilic treatment if necessary. Examples of the hydrophilization treatment include alkali metal silicates as disclosed in US Pat. Nos. 2,714,066, 3,181,461, 3,280,734 and 3,902,734. (For example, sodium silicate aqueous solution) method. 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 U.S. Pat. Nos. 3,276,868, 4,153,461, and 4,689,272. A method of treating with polyvinyl phosphonic acid is used.

The infrared-sensitive positive lithographic printing plate precursor used in the present invention has at least an image forming layer on a support, and the image forming layer may be a single layer, or an upper image forming layer and a lower layer. Although two layers are laminated, an undercoat layer can be provided between the support and the image forming layer or the lower layer as necessary.
Various organic compounds are used as the primer layer component. For example, phosphonic acids having an amino group such as carboxymethylcellulose, dextrin, gum arabic, 2-aminoethylphosphonic acid, and phenylphosphonic acid which may have a substituent Organic phosphonic acids such as naphthyl phosphonic acid, alkyl phosphonic acid, glycero phosphonic acid, methylene diphosphonic acid and ethylene diphosphonic acid, phenyl phosphoric acid, naphthyl phosphoric acid, alkyl phosphoric acid and glycerophosphoric acid which may have a substituent Organic phosphoric acid, optionally substituted phenylphosphinic acid, naphthylphosphinic acid, alkylphosphinic acid, glycerophosphinic acid and other organic phosphinic acids, glycine and β-alanine amino acids, and triethanolamine hydrochloric acid Has a hydroxy group such as salt -Alanine, and hydrochlorides of amines that may be used in combination of two or more.

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.

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 , -CONHR ¹⁶ , -COR ¹⁷ or -CN, or R ¹² and R ¹³ may be bonded to form a ring, and R ^{14 to} R ¹⁷ are each independently an alkyl group or Represents 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 represent a hydrogen atom, an alkyl group, a substituted alkyl group, an aryl group, or a substituted aryl. Represents a group, or R ¹⁸ and R ¹⁹ may combine to form a ring, and m represents an integer of 1 to 3.

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 obtained by dissolving the organic compound in an organic solvent or a mixed solvent thereof to adsorb the compound, and then washed with water 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 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. A yellow dye can also be added to improve the tone reproducibility of the image forming layer.
The coverage of the organic undercoat layer, from the viewpoint of obtaining sufficient printing performance, is suitably 2 to 200 mg / m ^2, preferably from 5 to 100 mg / m ^2.

  In order to prevent the image recording layer from being scratched when it is overlaid on the back surface of the infrared-sensitive lithographic printing plate precursor obtained by providing the image recording layer, a coating layer comprising an organic polymer compound (Referred to as “back coat layer”).

The infrared-sensitive positive lithographic printing plate precursor prepared as described above is imagewise exposed and then developed with an alkaline developer as described in detail above.
Examples of the active light source used for image exposure include a mercury lamp, a metal halide lamp, a xenon lamp, and a chemical lamp. Examples of the laser beam include a helium / neon laser (He—Ne laser), an argon laser, a krypton laser, a helium / cadmium laser, a KrF excimer laser, a solid laser, a semiconductor laser, a YAG laser, and a YAG-SHG laser. .

The lithographic printing plate developed according to the method of the present invention is post-treated with a rinsing solution containing washing water or a surfactant, a desensitizing solution containing gum arabic or a starch derivative. In this post-treatment, these treatment liquids can be variously combined.
If the lithographic printing plate obtained by image exposure, development, washing and / or rinsing and / or gumming has an unnecessary image area, the unnecessary image area 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 obtained as described above can be subjected to a printing process after applying a desensitized gum if desired, but if it is desired to obtain a lithographic printing plate with higher printing durability, Processing is performed. In the case of burning a lithographic printing plate, the preparation as described in JP-B-61-2518, JP-A-55-28062, JP-A-1-31859, and JP-A-61-159655 is performed before burning. It is preferable to treat with a surface liquid.
As the method, a method of applying the lithographic printing plate with a sponge or absorbent cotton soaked with the surface-adjusting liquid, or immersing the printing plate in a vat filled with the surface-adjusting liquid, or applying an automatic coater Application by, for example, 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 weight). The lithographic printing plate 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.). . 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 subjected to the burning treatment can be subjected to conventional treatments such as washing, 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 and used for printing a large number of sheets.
EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, the scope of the present invention is not limited to these Examples.

Preparation of infrared sensitive positive planographic printing plate precursor 1 [Preparation of aluminum substrate]
An aluminum plate (material: JIS A 1050) with a thickness of 0.3 mm is etched for 10 seconds at a caustic soda concentration of 30 g / liter, an aluminum ion concentration of 10 g / liter, a liquid temperature of 60 ° C., washed with running water, and washed with 10 g / liter nitric acid. After neutralizing and washing with water. Using an alternating current having a sinusoidal waveform under the condition of applied voltage Va = 20 V, an electric current of 500 C / dm ² in an aqueous solution having a hydrogen chloride concentration of 15 g / liter, an aluminum ion concentration of 10 g / liter, and a liquid temperature of 30 ° C. After performing an electrochemical surface roughening treatment in an amount and washing with water, an etching treatment was performed for 10 seconds at a caustic soda concentration of 30 g / liter, an aluminum ion concentration of 10 g / liter, and a liquid temperature of 40 ° C., and then washed with running water. Next, it was desmutted in a sulfuric acid aqueous solution having a sulfuric acid concentration of 15% by mass and a liquid temperature of 30 ° C., and washed with water. Furthermore, in a 10% by mass sulfuric acid aqueous solution at a liquid temperature of 20 ° C., an anodizing treatment was performed under a condition of a current density of 6 A / dm ² by direct current so that the amount of the anodized film would be equivalent to 2.5 g / m ² , Dried. Then, it processed for 10 second at 30 degreeC with 2.5 mass% sodium silicate aqueous solution, and produced the board | substrate. The centerline average roughness (Ra) of the substrate was measured using a needle having a diameter of 2 μm and found to be 0.48 μm.
On the silicate-treated aluminum substrate obtained as described above, an undercoat solution having the following composition was applied and dried at 80 ° C. for 15 seconds to form a coating film. The coating amount of the coating film after drying was 17 mg / m ² .

・ The following compound (1) (weight average molecular weight 26,000) 0.3 g
・ Methanol 100g
・ Water 1g
Compound (1)

(Formation of image forming layer)
On the aluminum substrate after the undercoating treatment obtained as described above, an image forming layer lower layer coating solution having the following composition is applied with a wire bar having a wet coating amount of 19 cc / m ² , and the coating amount is 1.0 g / m ^2. Then, it was dried at 150 ° C. for 60 seconds by a continuous plate-passing drying apparatus (drying oven) of a convection heating method using warm air. Next, the image forming layer upper layer coating liquid shown below was applied onto the obtained lower layer with a wire bar so that the wet coating amount was 7.5 cc / m ² , and the total coating amount was 1.2 g / m. ^Two . After coating, in the same manner as described above, the plate was dried at 140 ° C. for 70 seconds using a drying apparatus to prepare a lithographic printing plate precursor 1.

[Coating solution for lower layer of image forming layer]
N- (4-aminosulfonylphenyl) methacrylamide /
Acrylonitrile / methyl methacrylate copolymer (36/34/30: weight average molecular weight 50,000) 1.896 g
Cresol novolak (m / p = 6/4 weight average molecular weight 4,500,
Residual monomer 0.8wt%) 0.237g
・ Cyanine dye A (the following structure) 0.109 g
・ 4,4'-bishydroxyphenylsulfone 0.063g
・ Tetrahydrophthalic anhydride 0.190g
・ 0.008 g of p-toluenesulfonic acid
・ The ethyl violet counter ion is changed to 6-hydroxynaphthalene sulfone 0.05 g
・ Fluorine surfactant (Megafac F176,
Dainippon Ink Industry Co., Ltd.) 0.035g
・ Methyl ethyl ketone 26.6g
1-methoxy-2-propanol 13.6 g
・ Γ-Butyrolactone 13.8g

Cyanine dye A

[Coating solution for upper layer of image forming layer]
・ M, p-cresol novolak (m / p ratio = 6/4, weight average molecular weight 4500, containing 0.8% by weight of unreacted cresol) 0.237 g
・ Cyanine dye A (above structure) 0.047g
・ Dodecyl stearate 0.060g
・ 3-methoxy-4-diazodiphenylamine hexafluorophosphate 0.030 g
・ Fluorine surfactant (Megafac F176,
Dainippon Ink & Chemicals, Inc.) 0.110g
-Fluorosurfactant (Megafac MCF-312 (30%),
0.120g made by Dainippon Ink Industries, Ltd.
・ Methyl ethyl ketone 15.1 g
・ 1-methoxy-2-propanol 7.7 g

Preparation of infrared sensitive positive planographic printing plate precursor 2 [Preparation of aluminum substrate]
A 0.3 mm thick aluminum plate (material 1050) was washed with trichlorethylene and degreased, and then a nylon brush and 400 mesh pumice-water suspension were used to make the surface grainy and washed thoroughly with water.
After washing, this aluminum plate was etched by immersing it in a 25% aqueous sodium hydroxide solution at 45 ° C. for 9 seconds, washed with water, further immersed in a 20% nitric acid aqueous solution for 20 seconds, and washed again with water. At this time, the etching amount of the grained surface was about 3 g / m ² .
Next, the aluminum plate was provided with an anodized film of 3 g / m ² with a direct current of 15 A / dm ² using 7% sulfuric acid as an electrolytic solution, and then washed and dried.
This was treated with a 2.5% aqueous solution of sodium silicate at 30 ° C. for 10 seconds, the following undercoat layer coating solution was applied, and dried at 80 ° C. for 15 seconds to obtain a support. The dry coating amount of the undercoat layer after drying was 15 mg / m ² .

<Coating liquid for undercoat layer>
The following copolymer P (molecular weight 28000) 0.3 g
Methanol 100g
1g of water
Copolymer P

Synthesis Example 1 (B1 component: synthesis of an alkali-soluble polymer compound (copolymer) having a carboxyl group)
In a 20 ml three-necked flask equipped with a stirrer, a condenser and a dropping funnel, 6.39 g (0.045 mol) of n-propyl methacrylate, 1.29 g (0.015 mol) of methacrylic acid and 1-methoxy-2- 20 g of propanol was added, and the mixture was stirred while being heated to 65 ° C. with a hot water bath. To this mixture, 0.15 g of “V-601” (manufactured by Wako Pure Chemical Industries, Ltd.) was added, and the mixture was stirred for 2 hours under a nitrogen stream while maintaining at 70 ° C. To this reaction mixture, 6.39 g (0.045 mol) of n-propyl methacrylate, 1.29 g (0.015 mol) of methacrylic acid, 20 g of 1-methoxy-2-propanol and 0.15 g of “V-601” were added. The mixture was added dropwise via a dropping funnel over 2 hours. After completion of the dropwise addition, the resulting mixture was further stirred at 90 ° C. for 2 hours. After completion of the reaction, 40 g of methanol is added to the mixture, the mixture is cooled, and the resulting mixture is poured into 2 liters of water while stirring the water. After stirring the mixture for 30 minutes, the precipitate is removed by filtration and dried. Gave 15 g of a white solid.
When the weight average molecular weight (polystyrene standard) of this copolymer was measured by gel permeation chromatography, it was 53,000.

Synthesis Example 2 (B1 component: synthesis of an alkali-soluble polymer compound (copolymer) having a carboxyl group)
By the same operation as in Synthesis Example 1, a copolymer was synthesized using ethyl methacrylate / isobutyl methacrylate / methacrylic acid (mol%: 35/35/30). The weight average molecular weight (polystyrene standard) was measured and found to be 50,000.

Synthesis example 3 (B1 component: Synthesis of polyurethane resin having carboxyl group)
Into a 500 ml three-necked round bottom flask equipped with a condenser and a stirrer was added 14.6 g (0.109 mol) of 2,2-bis (hydroxymethyl) propionic acid and 13.3 g (0.0686 mol) of tetraethylene glycol. ) And 2.05 g (0.0228 mol) of 1,4-butanediol were added and dissolved in 118 g of N, N-dimethylacetamide. To this, 30.8 g (0.123 mol) of 4,4′-diphenylmethane diisocyanate, 13.8 g (0.0819 mol) of hexamethylene diisocyanate and 0.1 g of di-n-butyltin dilaurate as a catalyst were added and stirred. Under heating at 90 ° C. for 7 hours.
N, N-dimethylacetamide (100 ml), methanol (50 ml) and acetic acid (50 ml) were added to the reaction solution, and the mixture was stirred and then added to 4 liters of water with stirring to precipitate a white polymer. The polymer was separated by filtration, washed with water, and dried under reduced pressure to obtain 60 g of polymer.
When the molecular weight was measured by gel permeation chromatography (GPC), the weight average (polystyrene standard) was 70,000. The carboxyl group content measured by titration was 1.43 meq / g.

及び以下のジオール化合物（モル％）

を用いて、合成例３と同様にして共重合体を合成した。得られた共重合体の滴定による酸含量は１．７２meq／ｇであり、重量平均分子量（ポリスチレン標準）は８０，０００であった。 Synthesis example 4 (B1 component: Synthesis of polyurethane resin having carboxyl group)
The following diisocyanate compounds (mol%)

And the following diol compounds (mol%)

Was used in the same manner as in Synthesis Example 3 to synthesize a copolymer. The acid content of the obtained copolymer by titration was 1.72 meq / g, and the weight average molecular weight (polystyrene standard) was 80,000.

Synthesis example 5
A 500 ml three-necked flask equipped with a stirrer, a condenser and a dropping funnel is charged with 31.0 g (0.36 mol) of methacrylic acid, 39.1 g (0.36 mol) of ethyl chloroformate 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-aminobenzenesulfonamide was added, and the mixture was stirred for 1 hour while warming to 70 ° C. in an oil bath. After completion of the reaction, this 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 resulting solid was dried to give white N- (p-aminosulfonylphenyl) methacrylamide. A solid was obtained (yield 46.9 g).

  Next, 4.61 g of N- (p-aminosulfonylphenyl) methacrylamide (0.0192 mol) and 2.94 g of ethyl methacrylate (0.0258) were added to a 20 ml three-necked flask equipped with a stirrer, a condenser and a dropping funnel. Mol), 0.80 g (0.015 mol) of acrylonitrile and 20 g of N, N-dimethylacetamide were added, and the mixture was stirred while being heated to 65 ° C. in a hot water bath. To this mixture, 0.15 g of “V-65” (manufactured by Wako Pure Chemical Industries, Ltd.) was added, and the mixture was stirred for 2 hours under a nitrogen stream while maintaining at 65 ° C. A further mixture of 4.61 g of N- (p-aminosulfonylphenyl) methacrylamide, 2.94 g of ethyl methacrylate, 0.80 g of acrylonitrile, N, N-dimethylacetamide and 0.15 g of “V-65” was added to this reaction mixture. It dropped by the 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 is added to the mixture, the mixture is cooled, and the resulting mixture is poured into 2 liters of water while stirring the water. After stirring the mixture for 30 minutes, the precipitate is removed by filtration and dried. Gave 15 g of a white solid. It was 53,000 when the weight average molecular weight (polystyrene standard) of this specific copolymer was measured by the gel permeation chromatography.

The following image forming layer coating solution was applied on the obtained support and dried at 150 ° C. for 30 seconds to obtain a dry coating amount of 1.8 g / m ² , thereby obtaining a lithographic printing plate precursor 2.
<Coating liquid for image forming layer>
Copolymer of Synthesis Example 2 0.050g
Copolymer of Synthesis Example 4 0.050 g
0.4 g of copolymer of Synthesis Example 5
0.6 g of m, p-cresol novolak
(M / p ratio = 6/4, weight average molecular weight 8000,
0.5% unreacted cresol)
Cyanine dye A 0.1g
Phthalic anhydride 0.05g
0.002 g of p-toluenesulfonic acid
Ethyl violet 0.02g
(Counterion: 6-hydroxy-β-naphthalenesulfonic acid)
0.01 g of esterified product of naphthoquinone 1,2-diazide-5-sulfonyl chloride and pyrogallol-acetone resin
Fluorosurfactant 0.05g
(Product name: Megafuck F-177, manufactured by Dainippon Ink & Chemicals, Inc.)
Methyl ethyl ketone 8g
1-methoxy-2-propanol 4g

[Preparation of developer]
[Developer 1]
D-sorbite 0.22 mol / liter, potassium hydroxide 0.22 mol / liter, potassium citrate 18 g / liter, amphoteric surfactant Pione C-158G (manufactured by Takemoto Yushi Co., Ltd.) 0.5 g / liter, formula (1-1) Ethylenediamine disuccinic acid 0.5 g / liter was added to make a developer 1. The conductivity of this developer was about 45 mS / cm. The pH was 13.0.
[Developer 2]
D-sorbite 0.22 mol / liter, potassium hydroxide 0.22 mol / liter, potassium citrate 18 g / liter, amphoteric surfactant Pione C-158G (manufactured by Takemoto Yushi Co., Ltd.) 0.5 g / liter, formula (1-2) Propylenediamine disuccinic acid 0.5 g / liter 0.5 g / liter was added to make developer 2. The conductivity of this developer was about 45 mS / cm. The pH was 13.0.

[Developer 3]
D-sorbite 0.22 mol / liter, potassium hydroxide 0.22 mol / liter, potassium citrate 18 g / liter, amphoteric surfactant Pione C-158G (manufactured by Takemoto Yushi Co., Ltd.) 0.5 g / liter, formula (1-3) Butylene diamine disuccinic acid 0.5 g / liter 0.5 g / liter was added to make developer 2. The conductivity of this developer was about 45 mS / cm. The pH was 13.0.
[Developer 4]
D-sorbitol 0.19 mol / liter, potassium hydroxide 0.19 mol / liter, potassium citrate 18 g / liter, amphoteric surfactant Pione C-158G (manufactured by Takemoto Yushi Co., Ltd.) 0.5 g / liter, formula (1-4) Ethylenediamine disuccinic acid tetrasodium salt 0.5 g / liter was added to make developer 1. The conductivity of this developer was about 45 mS / cm. The pH was 13.0.

[Developer 5]
D-sorbitol 0.19 mol / liter, potassium hydroxide 0.19 mol / liter, potassium citrate 18 g / liter, amphoteric surfactant Pione C-158G (manufactured by Takemoto Yushi Co., Ltd.) 0.5 g / liter, formula (1-5) Propylenediamine disuccinic acid tetrasodium salt 0.5 g / liter was added to make developer 1. The conductivity of this developer was about 45 mS / cm. The pH was 13.0.
[Developer 6]
D-sorbitol 0.19 mol / liter, potassium hydroxide 0.19 mol / liter, potassium citrate 18 g / liter, amphoteric surfactant Pione C-158G (manufactured by Takemoto Yushi Co., Ltd.) 0.5 g / liter, formula (1-6) Butylene diamine disuccinic acid tetrasodium salt 0.5 g / liter was added to make developer 1. The conductivity of this developer was about 45 mS / cm. The pH was 13.0.

[Comparative developer 1]
D-sorbite 0.22 mol / liter, potassium hydroxide 0.22 mol / liter, potassium citrate 18 g / liter, amphoteric surfactant Pione C-158G (manufactured by Takemoto Yushi Co., Ltd.) 0.5 g / liter A comparative developer developer 1 was added. The conductivity of this developer was about 45 mS / cm. The pH was 13.0.
[Comparative developer 2]
D-sorbitol 0.22 mol / liter, potassium hydroxide 0.22 mol / liter, potassium citrate 18 g / liter, amphoteric surfactant Pione C-158G (manufactured by Takemoto Yushi Co., Ltd.) 0.5 g / liter, iminozi Acetic acid 0.5 g / liter was added to make a comparative developer developer 1. The conductivity of this developer was about 45 mS / cm. The pH was 13.0.
[Comparative developer 3]
D-sorbite 0.22 mol / liter, potassium hydroxide 0.22 mol / liter, potassium citrate 18 g / liter, amphoteric surfactant Pione C-158G (manufactured by Takemoto Yushi Co., Ltd.) 0.5 g / liter, β Alanine diacetic acid 0.5 g / liter was added to make a comparative developer 1. The conductivity of this developer was about 45 mS / cm. The pH was 13.0.

Sensitivity, scratch resistance, adhesion of development residue, and ink inking property of the lithographic printing plate were evaluated as follows in the lithographic printing plate making [sensitivity evaluation].
The lithographic printing plate precursors 1 and 2 obtained as described above were prepared as described above after drawing a solid image with a Trend setter manufactured by Creo at a beam intensity of 2 to 10 W and a drum rotation speed of 150 rpm. Using Fuji Photo Film Co., Ltd. PS processor LP940H charged with various developers and Fuji Photo Film Co., Ltd. finisher FG-1 (diluted 1: 1), the liquid temperature was kept at 30 ° C. and the development time was Developed in 12 seconds.
The developed plate is observed with a magnifying glass of 25 times, the presence or absence of a residual film that does not substantially cause printing stains is evaluated, the actual exposure energy is calculated from the exposure beam intensity at which no residual film is observed, and the sensitivity It was used as an index. The smaller the exposure energy (unit: W), the higher the sensitivity. The results are shown in Tables 1 and 2.

[Scratch resistance evaluation]
The lithographic printing plate precursors 1 and 2 were loaded with one rotor CS-0 wrapped with slip paper with a rotary ablation tester (manufactured by TOYOSEIKI), and the plate was rotated 10 times with a 250 g load applied. . Then, using Fuji Photo Film Co., Ltd. PS processor LP940H charged with various developers and Fuji Photo Film Co., Ltd. finisher FG-1 (diluted 1: 1), the liquid temperature was kept at 30 degrees, Developed with a development time of 12 seconds. In the developed plate, the density difference between the portion where the rotor was rotated and the portion where the rotor was not rotated was measured in the cyan mode of a Gretag D19C reflection densitometer (manufactured by Gretag Macbeth). The smaller the numerical value of the density difference, the better the scratch resistance. The results are shown in Tables 1 and 2.

[Evaluation of development residue adhesion]
After lithographic printing plate masters 1 and 2 were drawn with a Creo Trendsetter VX with a beam intensity of 8 W, a drum rotation speed of 150 rpm and an AM screen of 175 lpi and a 50% flat net, a PS processor LP940HII made by Fuji Photo Film Co., Ltd. Each developer was developed at a developing temperature of 12 seconds while being maintained at 30 ° C., and finished with Finisher FG-1 (diluted 1: 1) manufactured by Fuji Photo Film Co., Ltd. For development residue adhesion, 30 plates each of 1030 × 800 mm were processed under the above conditions, and the average number of residue residues per plate was determined.

[Evaluation of ink fillability]
The lithographic printing plate precursors 1 and 2 were loaded into a plate material supply device, fully automatically and continuously exposed, developed with the above-described various developing solutions, and discharged to a stocker. The resolution at the time of exposure was 2400 dpi, 175 lines, and the halftone dots were changed in the range of 0.5 to 99.5%. The obtained lithographic printing plate was printed using a GEOS G black (N) manufactured by Dainippon Ink Co., Ltd. with an R201 type printer manufactured by Man Roland, and the number of sheets on which the ink was applied was evaluated.

Table 1: Infrared sensitive positive planographic printing plate precursor 1

Table 2: Plate making from infrared sensitive positive planographic printing plate precursor 2

  From the above results, it can be seen that the method of the present invention can achieve plate making with high sensitivity and high scratch resistance. Further, the obtained plate has good ink inking properties. Further, according to the plate making method of the present invention, the development residue adheres to the plate very little.

Claims (3)

An infrared-sensitive positive lithographic printing plate precursor having an infrared-absorbing dye and an image-forming layer containing a water-insoluble and alkali-soluble resin is exposed to infrared light and then developed with an alkali developer containing a compound represented by the following general formula (1) A plate-making method of a lithographic printing plate, characterized by processing.

(In the formula, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ and R ₆ each represents a hydrogen atom or an aliphatic hydrocarbon group. W represents a divalent linking group containing a carbon atom. M ₁ , M ₂ , M ₃ and M ₄ each represent a hydrogen atom or an alkali metal cation.)   The infrared-sensitive positive lithographic printing plate precursor comprises an upper image forming layer containing an infrared absorbing dye and a water-insoluble and alkali-soluble resin, and a lower layer containing a water-insoluble and alkali-soluble resin therebelow. Plate making method of lithographic printing plate.   The lithographic printing plate making method according to claim 2, wherein the lower layer of the water-insoluble and alkali-soluble resin is an acrylic resin.