JP5388918B2 - Infrared laser positive lithographic printing plate precursor and lithographic printing plate making method - Google Patents

Description

  The present invention relates to a positive lithographic printing plate precursor for infrared laser and a method for making a lithographic printing plate.

  Conventionally, various photosensitive compositions have been used as visible image forming and lithographic printing plate materials. In particular, the development of lasers in lithographic printing in recent years is remarkable, and in particular, high-power and small-sized products are readily available for solid-state lasers and semiconductor lasers having a light emitting region from near infrared to infrared. These lasers are very useful as an exposure light source when directly making a plate from digital data such as a computer.

  The positive lithographic printing plate precursor for infrared laser contains an alkali-soluble binder resin and an IR dye that absorbs light and generates heat as essential components. The IR dye or the like acts as a development inhibitor that substantially reduces the solubility of the binder resin in the developer by interaction with the binder resin in the unexposed area (image area), and in the exposed area (non-image area). The generated heat weakens the interaction between the IR dye and the binder resin and dissolves in an alkaline developer to form a lithographic printing plate. However, in such a positive lithographic printing plate material for infrared laser, the processability (development latitude) with a fatigue developer having a decreased activity is not sufficient.

  In order to solve such a problem of development latitude, it is conceivable to use a recording layer made of a material that can develop a non-image area more easily, that is, has a property of better solubility in an alkaline aqueous solution. However, such a recording layer is chemically weak even in the image area, and is easily damaged by a developer, an ink washing solvent used during printing, a plate cleaner, and the like. There was a problem of poor chemical resistance.

  In order to solve this problem, a method is used in which a recording layer is laminated and a polyurethane resin having good solubility in an alkaline aqueous solution and having high durability is used as an upper layer and / or a lower layer. (Patent Documents 1 and 2).

  However, the difference between the dissolution resistance of the unexposed area (image area) to the developer and the solubility of the exposed area (non-image area) under various use conditions (dissolution discrimination; ) Is still not sufficient, and there is a problem that over-development and poor development are likely to occur due to fluctuations in usage conditions, and it has excellent durability in the development latitude and unexposed areas, and further, dissolution is suppressed by exposure. After the release of the action, a resin material having the property of excellent developability has been eagerly desired.

  On the other hand, a lithographic printing plate having a polyurethane resin having a macromonomer unit having an acidic hydrogen atom in its side chain has been disclosed for the purpose of improving solvent resistance and durability (Patent Document 3). However, there is no suggestion of an effect on the development latitude and dissolution discrimination of the positive lithographic printing plate precursor for infrared laser as described above.

JP 2003-177533 A JP 2007-17913 A Japanese Patent Laid-Open No. 10-312058

  The problem to be solved by the present invention is, firstly, to provide a positive lithographic printing plate precursor for an infrared laser having excellent development latitude, dissolution discrimination, and high durability (printing durability). Secondly, the problem to be solved by the present invention is to provide a positive lithographic printing plate precursor for an infrared laser that has little deterioration in developability over time after exposure (good shrinkage).

The above-described problems of the present invention have been solved by the following means <1> and <9>. They are listed together with <2> to <8> and <10>, which are preferred embodiments.
<1> On the support, a lower layer containing a graft copolymer having an alkali-soluble group and an upper layer whose solubility in an aqueous alkali solution is increased by exposure, and the lower layer and / or the upper layer absorb infrared rays. A positive lithographic printing plate precursor for infrared laser, wherein the graft copolymer in the lower layer is a polyurethane having a structural unit derived from an ethylenically unsaturated monomer as a graft chain,
<2> The positive lithographic printing plate precursor for infrared laser according to <1>, wherein the polyurethane is a reaction product of a diisocyanate and a diol,
<3> The positive lithographic printing plate precursor for infrared laser according to <1> or <2>, wherein the graft chain contains an acidic hydroxyl group and / or an acidic amino group as an alkali-soluble group,
<4> The positive lithographic printing plate precursor for infrared laser according to any one of <1> to <3>, wherein a terminal of the graft chain is bonded to a diol compound residue via a sulfur atom,
<5> The graft chain contains, as an alkali-soluble group, a group selected from the group consisting of a sulfonamide group, an active imide group, a sulfonic acid group, a phosphoric acid group, and a phosphonic acid group, <1> to <4 > Positive lithographic printing plate precursor for infrared laser according to any one of
<6> The infrared laser according to any one of <1> to <5>, wherein the graft chain contains a group selected from the group consisting of a sulfonamide group and an active imide group as an alkali-soluble group. Positive lithographic printing plate precursor,
<7> The infrared laser according to <2>, wherein the diol includes a diol containing a carboxy group and a diol having a graft chain containing a group selected from the group consisting of a sulfonamide group and an active imide group. Positive lithographic printing plate precursor,
<8> The lithographic printing plate precursor for infrared laser according to any one of <1> to <7>, wherein the upper layer contains an infrared absorber,

<9> An exposure step for image exposure of the lithographic printing plate precursor according to any one of <1> to <8>, and a development step for development using an alkaline aqueous solution having a pH of 8.5 to 10.8. Plate making method of planographic printing plate including in this order,
<10> The plate making method of a lithographic printing plate as described in <9>, wherein the alkaline aqueous solution further contains an anionic surfactant or a nonionic surfactant.

  According to the present invention, it is possible to provide a positive lithographic printing plate precursor for infrared laser having excellent development latitude and dissolution discrimination and high durability (printing durability). Furthermore, the positive lithographic printing plate precursor for an infrared laser that can be stably and satisfactorily developed even when printing is performed can be provided. Furthermore, even if the lithographic printing plate of the present invention is made over a long period of time, it has been possible to provide a plate making method that hardly causes residue accumulation in the developer.

It is explanatory drawing which shows schematic structure of an automatic developing processor.

The positive type lithographic printing plate precursor for infrared laser of the present invention comprises a support and a lower layer containing a graft copolymer having an alkali-soluble group and an upper layer whose solubility in an aqueous alkali solution is increased by exposure. The lower layer and / or upper layer contains an infrared absorber, and the lower layer graft copolymer is a polyurethane having a structural unit derived from an ethylenically unsaturated monomer as a graft chain.
The positive-type lithographic printing plate precursor is a lithographic printing plate precursor that is widely sensitive to infrared rays and is particularly suitable for infrared laser exposure and gives a positive-type image. In this lithographic printing plate precursor, two layers of a lower layer and an upper layer are laminated as essential layers on a support. In addition to these two upper and lower layers, a hydrophilic undercoat layer or the like may be appropriately provided between the support and the lower layer. The lower layer contains a graft copolymer having an alkali-soluble group, and this lower layer is insoluble in neutral water and soluble in an aqueous alkali solution by processing for a standard development time. Here, neutral water means neutral ion-exchanged water, and alkaline aqueous solution means an alkaline aqueous solution having a pH of 8.5 to 13.5.
The upper layer has a property of increasing the solubility in an aqueous alkali solution by infrared exposure. The graft copolymer having an alkali-soluble group contained in the lower layer is a polyurethane having a structural unit derived from an ethylenically unsaturated monomer as a graft chain.

Although the mechanism of action in the planographic printing plate precursor of the present invention is not clear, it is presumed as follows. Polyurethane having high durability has high cohesiveness as a polymer, tends to have low developer permeability, is easily affected by developer activity, and has insufficient development latitude. On the other hand, when the design is made to increase the permeability of the developer, the development latitude increases, but the durability of the printing plate decreases, resulting in a trade-off relationship. In contrast, since the polyurethane of the present invention has a graft copolymer structure, the durability of the lithographic printing plate based on the high cohesiveness of the polyurethane is maintained, and the movement of the graft chain is high when the developer penetrates. Therefore, it is presumed that deterioration in developability is suppressed even with a developer having reduced activity.
Hereinafter, the details of the positive planographic printing plate precursor of the present invention will be described.

(Graft copolymer contained in the lower layer)
The lower layer contains a graft copolymer resin. The main chain of the graft copolymer is polyurethane, and the polyurethane is preferably a reaction product of diisocyanate and diol. Therefore, the main chain made of copolymer polyurethane is linear.
The graft chain preferably contains an acidic hydroxyl group and / or an acidic amino group as an alkali-soluble group. The alkali-soluble group is preferably selected from the group consisting of a sulfonamide group, an active imide group, a sulfonic acid group, a phosphoric acid group, and a phosphonic acid group, and is selected from the group consisting of a sulfonamide group and an active imide group. More preferably.

The graft chain of the graft copolymer has a structural unit derived from an ethylenically unsaturated monomer. The graft copolymer has the above alkali-soluble group.
The end of the graft chain is preferably bonded to a diol residue of the polyurethane main chain via a sulfur atom. A diol having such a chemical structure is obtained by radical polymerization of an ethylenically unsaturated monomer in the presence of a compound having a mercapto group and two hydroxyl groups (a diol having a mercapto group) as a so-called chain transfer agent. can get.
The diol used for the synthesis of the polyurethane preferably includes a diol containing a carboxy group and a diol having a graft chain containing a group selected from the group consisting of a sulfonamide group and an active imide group.

The graft copolymer used in the present invention preferably has a weight average molecular weight of 5,000 to 800,000, more preferably 10,000 to 100,000, and 20,000 to 30,000. It is particularly preferred. The weight average molecular weight of the macromonomer (per graft chain) is preferably 500 or more and 20,000 or less, more preferably 800 to 15,000, and particularly preferably 800 to 10,000. .
The weight ratio of polyurethane in the graft copolymer is preferably 20 to 80% by weight, and more preferably 30 to 60% by weight.
The acid value of the graft copolymer is preferably 0.50 to 4.0 mmol / g, more preferably 2.40 to 3.50 mmol / g, from the viewpoints of developability and printing durability.

Hereinafter, a method for synthesizing a polyurethane having a structural unit derived from an ethylenically unsaturated monomer as a graft chain will be described in more detail.
<Polyurethane having macromonomer units in the side chain>
For the synthesis of the graft copolymer having an alkali-soluble group used in the present invention, reference can be made to a macromonomer having an acidic hydrogen atom and a method for producing a polyurethane. Nos. 178416 and 4-178417.

In the present invention, a “macromonomer” refers to a polymer having two alcoholic hydroxyl groups at one end that allow it to behave as a monomer.
Examples of the macromonomer having an acidic hydrogen atom that can be used in the present invention include vinyl polymerization resins such as polyacrylates, polystyrenes, polyvinyl ethers, and polyacrylonitriles. The addition reaction using a vinyl polymerization system can be cited as an example of a macromonomer that can be particularly suitably used, and a macromonomer having two hydroxyl groups obtained by radical polymerization of a monomer having an ethylenically unsaturated group is preferred. . Hereinafter, this macromonomer will be described as an example.

  Examples of the monomer having an ethylenically unsaturated group used in the production of a macromonomer having two hydroxyl groups obtained by radical polymerization of a monomer having an ethylenically unsaturated group of the present invention include methyl acrylate, Ethyl acrylate, propyl acrylate, butyl acrylate, amyl acrylate, ethyl hexyl acrylate, octyl acrylate, tert-octyl acrylate, chloroethyl acrylate, 2,2-dimethylhydroxypropyl acrylate, 5-hydroxypentyl acrylate, Acrylic esters such as trimethylolpropane monoacrylate, pentaerythritol monoacrylate, glycidyl acrylate, benzyl acrylate, methoxybenzyl acrylate, tetrahydroacrylate, phenyl acrylate Aryl acrylates such as furfuryl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, amyl methacrylate hexyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, chlorobenzyl methacrylate, octyl methacrylate, 4-hydroxybutyl methacrylate, 5-hydroxypentyl Methacrylates such as methacrylate, 2,2-dimethyl-3-hydroxypropyl methacrylate, trimethylolpropane monomethacrylate, pentaerythritol monomethacrylate, glycidyl methacrylate, furfuryl methacrylate, tetrahydrofurfuryl methacrylate, phenyl methacrylate, cresylme Acrylate, such as aryl methacrylates of naphthyl methacrylate can be exemplified. Examples of acrylamide or derivatives thereof include N-methyl acrylamide, N-ethyl acrylamide, N-propyl acrylamide, N-butyl acrylamide, Nt-butyl acrylamide, N-heptyl acrylamide, N-octyl acrylamide, N-cyclohexyl acrylamide, N-alkylacrylamides such as N-benzylacrylamide, N-phenylacrylamide, N-tolylacrylamide, N-nitrophenylacrylamide, N-naphthylacrylamide, N-arylacrylamides such as N-hydroxyphenylacrylamide, N, N- Dimethylacrylamide, N, N-diethylacrylamide, N, N-dibutylacrylamide, N, N-dibutylacrylamide, N, N-diisobutyl N, N-dialkylacrylamides such as chloramide, N, N-diethylhexylacrylamide, N, N-dicyclohexylacrylamide, N-methyl-N-phenylacrylamide, N-hydroxyethyl-N-methylacrylamide, N-2-acetamide N, N-arylacrylamides such as ethyl-N-acetylacrylamide, methacrylamide or derivatives thereof include N-methylmethacrylamide, N-ethylmethacrylamide, N-propylmethacrylamide, N-butylmethacrylamide, Nt N-alkyl methacrylamides such as butyl methacrylamide, N-ethylhexyl methacrylamide, N-hydroxyethyl methacrylamide, N-cyclohexyl methacrylamide, N-phenyl methacrylate N-arylmethacrylamides such as amide, N-naphthylmethacrylamide: N, N-dialkylmethacrylamides such as N, N-diethylmethacrylamide, N, N-dipropylmethacrylamide, N, N-dibutylmethacrylamide N, N-diarylmethacrylamides such as N, N-diphenylmethacrylamide, N-hydroxyethyl-N-methylmethacrylamide, N-methyl-N-phenylmethacrylamide, N-ethyl-N-phenylmethacrylamide Allyl compounds such as methacrylamide derivatives, allyl acetate, allyl caproate, allyl caprylate, allyl laurate, allyl palmitate, allyl stearate, allyl benzoate, allyl acetoacetate, allyl lactate, allyloxyethanol, hexyl Vinyl ether, octyl vinyl ether, dodecyl vinyl ether, ethylhexyl vinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether, chloroethyl vinyl ether, 1-methyl-2,2-dimethylpropyl vinyl ether, 2-ethylbutyl vinyl ether, hydroxyethyl vinyl ether, diethylene glycol vinyl ether, dimethylamino Ethyl vinyl ether, diethyl aminoethyl vinyl ether, butyl amino ethyl vinyl ether, benzyl vinyl ether, tetrahydrofurfuryl vinyl ether, vinyl phenyl ether, vinyl tolyl ether, vinyl chlorophenyl ether, vinyl-2,4-dichlorophenyl ether, vinyl naphthyl ether, vinyl anthranil ether Vinyl ethers such as benzene, vinyl butyrate, vinyl isobutyrate, vinyl trimethyl acetate, vinyl diethyl acetate, vinyl valerate, vinyl caproate, vinyl chloroacetate, vinyl methoxy acetate, vinyl butoxy acetate, vinyl phenyl acetate, vinyl acetoacetate Vinyl lactate, vinyl-β-phenylbutyrate, vinyl cyclohexyl carboxylate, vinyl benzoate, vinyl salicylate, vinyl chlorobenzoate, vinyl tetrachlorobenzoate, vinyl esters such as vinyl naphthoate, methylstyrene, dimethylstyrene, Trimethyl styrene, ethyl styrene, diethyl styrene, isopropyl styrene, butyl styrene, hexyl styrene, cyclohexyl styrene, dode Silstyrene, benzylstyrene, chloromethylstyrene, trifluoromethylstyrene, ethoxymethylstyrene, acetoxymethylstyrene, methoxystyrene, 4-methoxy-3-methylstyrene, dimethoxystyrene, chlorostyrene, dichlorostyrene, trichlorostyrene, tetrachlorostyrene, Styrenes such as pentachlorostyrene, bromostyrene, dibromostyrene, iodostyrene, fluorostyrene, 2-bromo-4-trifluoromethylstyrene, 4-fluoro-3-trifluoromethylstyrene, butyl crotonate, hexyl crotonate, Crotonic acid esters such as crotonic acid and glycerin monocrotonate, dialkyl itaconates such as dimethyl itaconate, diethyl itaconate and dibutyl itaconate Dialkyls of maleic acid or fumaric acid such as dimethyl maleate and dibutyl fumarate, maleimide, N-phenylmaleimide, N-2-methylphenylmaleimide, N-2,6-diethylphenylmaleimide, N-2-chlorophenylmaleimide, Examples include maleimides such as N-cyclohexylmaleimide, N-laurylmaleimide, N-hydroxyphenylmaleimide, N-vinylpyrrolidone, N-vinylpyridine, acrylonitrile, methacrylonitrile and the like.

  The ethylenically unsaturated monomer used in the production of the macromonomer having two hydroxyl groups obtained by radical polymerization of the ethylenically unsaturated monomer of the present invention includes an alkali from the viewpoint of development latitude and exposure latitude. A monomer having a group containing an acidic hydroxyl group and / or an acidic amino group as a soluble group and an ethylenically unsaturated group is preferred.

  Examples of the monomer having an alkali-soluble group and an ethylenically unsaturated group used in the production of the macromonomer of the present invention include, for example, carboxyl groups such as acrylic acid, methacrylic acid, 4-vinylbenzoic acid, and radical polymerizability. Examples thereof include a monomer having an unsaturated group and a monomer containing a radically polymerizable unsaturated group having an acidic hydroxyl group, an acidic amide group, an active imide group, a sulfonic acid group, a phosphoric acid group and a phosphonic acid group. In particular, phenolic hydroxyl groups and radical polymerizable unsaturated groups such as N- (4-hydroxyphenyl) methacrylamide, monomethacryloyl hydroquinone, o-hydroxystyrene, p-hydroxystyrene, p-isopropenylphenol, m-isopropenylphenol. A monomer having a sulfonamide group and a radically polymerizable unsaturated group, such as N- (4-sulfamoylphenyl) methacrylamide, N-phenylsulfonylmethacrylamide, N-phenylsulfonylmaleimide, 2 A monomer having a sulfonic acid group and a radically polymerizable unsaturated group such as acrylamido-2-methylpropanesulfonic acid, a monomer having a phosphate group and a radically polymerizable unsaturated group such as 2-methacryloyloxyethyl phosphate Such as vinylphosphonic acid Monomers having a phosphonic acid group and a radical polymerizable unsaturated group or a monomer containing an active methylene group and a radical polymerizable unsaturated group of JP 63-127237 JP are preferably used.

  Among the acidic hydroxyl groups and / or acidic amino groups as the alkali-soluble group of the graft chain, from the viewpoint of interaction with the infrared absorbing dye, carboxyl group, sulfonamide group, active imide group, sulfonic acid group, phosphoric acid And those having a phosphonic acid group are more preferable, those having a sulfonamide group, an active imide group, a sulfonic acid group, a phosphoric acid group, and a phosphonic acid group are more preferable. Most preferred are those having a group.

  One of these monomers having an acidic hydroxyl group and / or an acidic amino group and a radical polymerizable unsaturated bond can be used alone, or a mixture of a plurality of monomers. Moreover, you may use as a mixture with the monomer which has a radically polymerizable unsaturated bond which does not contain said acidic group.

  In addition, as a monomer having an ethylenically unsaturated group used in the production of a macromonomer having two hydroxyl groups obtained by radical polymerization of a monomer having an ethylenically unsaturated group of the present invention, after the burning treatment From the viewpoint of printing durability, a monomer having a thermally crosslinkable group and an ethylenically unsaturated group is preferable. Here, the heat-crosslinking property means that it can be cured by heating at 200 ° C. for 5 minutes.

  Specific examples of the compound having a thermally crosslinkable group and an ethylenically unsaturated group include (meth) acrylamide represented by the formula (1) such as N- (hydroxymethyl) acrylamide and N- (butoxymethyl) acrylamide. A monomer having an ethylenically unsaturated group represented by formula (2), a monomer having an ethylenically unsaturated group represented by formula (3), and a urea group represented by formula (4) Or a monomer having a urethane group and an ethylenically unsaturated group, a monomer having an epoxy group and an ethylenically unsaturated group such as glycidyl methacrylate represented by the formula (5), represented by the formula (6) A monomer having an oxetanyl group and an ethylenically unsaturated group such as (3-methyl-3-oxetanyl) methyl methacrylate, and a monomer having an oxazoline group and an ethylenically unsaturated group represented by the formula (7) amount And the like. Among these, from the viewpoint of thermal crosslinkability, the monomer represented by the formula (1), the monomer represented by the formula (4), the monomer represented by the formula (5), the formula ( The monomer represented by 6) is more preferable, and the monomer represented by Formula (1) and the monomer represented by Formula (4) are more preferable.

The substituents in formulas (1) to (7) represent the following.
R ₁ represents a hydrogen atom or CH ₃ , R ₂ represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and R ₃ to R ₇ each independently represents a hydrogen atom or 1 to carbon atoms. 10 represents an alkyl group, and two or more groups may be bonded to form a ring structure, and R ₈ and R ₉ are each a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group, an alkenyl group, An alkynyl group or an aryl group is represented. A and B represent —O—, —S—, or —N (R ₁₀ ) —, R ₁₀ represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and X represents a single bond or two Represents a valent linking group.

As described above, the weight average molecular weight of the macromonomer thus obtained is preferably 500 or more and 20,000 or less, more preferably 800 to 15,000, and 800 to 10,000. It is particularly preferred.
Examples of the solvent for producing the macromonomer of the present invention include ethylene dichloride, cyclohexanone, methyl ethyl ketone, acetone, methanol, ethanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl glycol, 2-methoxyethyl acetate, 1-methoxy-2. -Propanol, 1-ethoxy-2-propanol, 1-methoxy-2-propyl acetate, 1-ethoxy-2-propyl acetate, 2-butanone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, Examples include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, toluene, ethyl acetate, methyl lactate, and ethyl lactate. These solvents may be used alone or in combination of two or more.

Examples of mercaptan chain transfer agents having two or more hydroxyl groups and one mercapto group used in the production of the macromonomer used in the present invention include 1-mercapto-1,1-methanediol and 1-mercapto. -1,1-ethanediol, 3-mercapto-1,2-propanediol, 2-mercapto-1,1-methanediol, 2-mercapto-2-methyl-1,3-propanediol, 2-mercapto-2 -Ethyl-1,3-propanediol, 1-mercapto-2,2-propanediol, 2-mercaptoethyl-2-methyl-1,3-propanediol, 2-mercaptoethyl-2-ethyl-1,3- Examples include propanediol.
The ethylenically unsaturated monomers used in the synthesis of specific examples MM-1 to 42 of the macromonomer are shown below. The chemical structures of the chain transfer agent C-1 and the monomers A-1 to 11 and O-1 to 6 used are as described below.

  The polyurethane having a macromonomer unit in the side chain used in this reaction is, for example, a single monomer having a radical polymerizable unsaturated bond in the presence of a mercaptan chain transfer agent having two hydroxyl groups and one mercapto group. Examples thereof include those obtained by reacting a macromonomer obtained by radical polymerization of the product as an essential component with at least one diisocyanate compound and, if necessary, other diol component as a diol component.

The polyurethane (A) can be produced by various methods. For example, a reaction product of a diisocyanate compound represented by the following formula (III) and a diol compound represented by the following formulas (I) and (II) having the above macromonomer as a diol component is a basic skeleton: And polyurethane.
OCN-R ¹ -NCO (III)

In the formula, R ¹ represents a divalent aliphatic or aromatic hydrocarbon which may have a substituent (for example, an alkyl, alkenyl, aralkyl, aryl, alkoxy, or halogeno group is preferable). If necessary, R ¹ may have another functional group that does not react with the isonanate group, such as an ester, urethane, amide, ureido group, or carbon-carbon unsaturated bond.

  Specific examples of the diisocyanate compound represented by the formula (III) 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-naphthylene diisocyanate, 3,3′-dimethylbiphenyl-4,4′-diisocyanate; aliphatic such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, lysine diisocyanate, dimer diisocyanate Diisocyanate compound, isophorone diisocyanate, 4,4′-methylenebis (cyclohexyl isocyanate), methylcyclohexane-2,4 (or 2,6) -diisocyanate, 1, Aliphatic diisocyanate compounds such as 3- (isocyanatomethyl) cyclohexane; diisocyanate compounds which are reaction products of diol and diisocyanate such as an adduct of 1 mol of 1,3-butylene glycol and 2 mol of tolylene diisocyanate, etc. It is done.

  (A) Polyurethane is a diol mixture obtained by combining a diol having an acidic hydrogen atom represented by the following formulas (IV) to (X) in addition to a diol compound in which the graft chain ends are bonded via a sulfur atom. A reaction product with a diisocyanate is preferable, and a reaction product between a diol mixture of a diol having a carboxy group represented by the formula (IV) and a diisocyanate is more preferable.

  The molecular weight of the polyurethane used in the present invention is preferably 5,000 to 800,000 in terms of weight average (polystyrene standard). A more preferred weight average molecular weight is 10,000 to 500,000, particularly preferably 20,000 to 200,000. The degree of dispersion (Mw / Mn) at this time is preferably 20 or less, more preferably 16 or less, and particularly preferably 14 or less. When the molecular weight is within the above range, the desired effect can be obtained.

The content of the polyurethane in the photosensitive composition is 1 to 30% by weight, preferably 2 to 20% by weight in terms of solid content. The polyurethane of the present invention is synthesized by adding the above-mentioned diisocyanate compound and diol compound in an aprotic solvent to a known catalyst having an activity corresponding to the reactivity and heating.
The molar ratio of the diisocyanate and diol compound to be used is preferably 0.8: 1 to 1.2: 1. If an isocyanate group remains at the end of the polymer, it is finally treated by treatment with alcohols or amines. In the form in which no isocyanate group remains.

  The polyurethane of the present invention may contain a diol component not containing an alkali-soluble group, and a diol represented by the following formula (I) or (II) can be exemplified as a constituent component.

In the formula, each R represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and n represents an integer of 2 or more.
As a C1-C8 alkyl group in R, a methyl group, an ethyl group, i-propyl group, n-propyl group, n-butyl group, i-butyl group etc. are mentioned, for example.

  Specific examples of the diol represented by the above formula (I) or (II) of the present invention are shown below, but the present invention is not limited thereto.

  Here, among the copolymerization components of polyurethane, obtained by radical polymerization of a monomer having a radical polymerizable unsaturated bond as an essential component in the presence of a mercaptan chain transfer agent having two hydroxyl groups and one mercapto group. The added weight of the macromonomer is preferably 5% by weight to 95% by weight, more preferably 20% by weight to 80% by weight, and particularly preferably 40% by weight to 70% by weight. .

As the macromonomer diol obtained by radical polymerization using a monomer having a radical polymerizable unsaturated bond as an essential component in the presence of a mercaptan chain transfer agent having two hydroxyl groups and one mercapto group, the MM- 1-42.
Among the exemplified macromonomers, preferred examples include macromonomers having a sulfonamide group of MM-10 to MM-13, macromonomers having a sulfonamide group of MM-40 and MM-41, and a thermally crosslinkable group. It is done.

  Preferred examples of the diisocyanate component include 2,4-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and mixtures of two or more thereof.

  Other diol components include 2,2-bis (hydroxymethyl) propionic acid, 2,2-bis (hydroxymethyl) butanoic acid and other diols having a carboxylic acid group, ethylene glycol, diethylene glycol, tetraethylene glycol, polypropylene glycol 700, polypropylene glycol 1000 and the like (poly) alkylene glycols, butanediol, hexanediol, decanediol, and diols such as decanediol are preferred in combination.

  As the diisocyanate component, 2,4-tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, or a mixture thereof, and as the diol component, the macromonomer and 2,2-bis (hydroxymethyl) propionic acid, 2 A combination with diols having a carboxylic acid group such as 2-bis (hydroxymethyl) butanoic acid is more preferred.

  As the solvent used when synthesizing the polyurethane, the same solvents as those used when synthesizing the macromonomer can be used.

Specific examples of polyurethane are shown below.
Among the exemplified polyurethanes, polyurethanes having a sulfonamide group of PU-10 to PU-13, and polyurethanes having a sulfonamide group and a thermally crosslinkable group such as PU-40 and PU-41 are preferable.

<Infrared absorber>
In the printing plate precursor of the present invention, the upper layer and / or the lower layer contains an infrared absorber, that is, an infrared absorbing dye or pigment as a photothermal conversion agent. Here, the photothermal conversion agent can be used without any limitation on the absorption wavelength range as long as it is a substance that absorbs light energy irradiation and generates heat, but it is suitable for use with a readily available high-power laser. Infrared absorbing dyes or pigments having an absorption maximum at a wavelength of 760 nm to 1,200 nm are preferable. The infrared absorber is preferably added to a layer away from the support, and more preferably added to the upper layer than the lower layer.

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

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

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

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

  Particularly preferred among these dyes are cyanine dyes, phthalocyanine dyes, oxonol dyes, squarylium dyes, pyrylium salts, thiopyrylium dyes, and nickel thiolate complexes. Further, the compound described on pages 26-38 of JP-A-2005-99685 is preferred because of its excellent photothermal conversion efficiency. In particular, the cyanine dye represented by formula (a) in JP-A-2005-99685 is preferred. When used in the photosensitive composition of the invention, it is most preferable because it gives high interaction with the alkali-soluble resin and is excellent in stability and economy.

Next, the upper layer whose solubility in an alkaline aqueous solution is increased by exposure will be described.
In order to form such an upper layer, it is preferable to use a novolac resin.
As the novolak resin used in the present invention, phenol formaldehyde resin, m-cresol formaldehyde resin, p-cresol formaldehyde resin, m- / p-mixed cresol formaldehyde resin, phenol / cresol (m-, p-, or m- / p -Any of mixing) Novolak resin such as mixed formaldehyde resin and pyrogallol acetone resin are preferable.

  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; Examples thereof include condensation polymers with formaldehyde. Moreover, it is preferable that the weight average molecular weight is 500 or more, and it is more preferable that it is 1,000-700,000. The number average molecular weight is preferably 500 or more, and more preferably 750 to 650,000. The dispersity (weight average molecular weight / number average molecular weight) is preferably 1.1 to 10.

  Further, the novolak resin used in the present invention is preferably 50% by weight or more in the total solid content of the photosensitive layer when the infrared-sensitive composition of the present invention is used as the upper layer of the lithographic printing plate. By doing so, the printing durability improvement effect by the burning treatment can be obtained. It is more preferably 70% by weight or more, and particularly preferably 80% by weight or more.

(Other additives)
In forming a recording layer including a lower layer and an upper layer, various additives can be further added as necessary as long as the effects of the present invention are not impaired in addition to the above components.
The additives listed below may be added only to the lower layer (lower layer) of the recording layer, may be added only to the uppermost layer (upper layer), or may be added to both layers.
For details of the following development accelerators, surfactants, print-out agents / colorants, plasticizers, waxes, and methods for forming the recording layer, the description in JP-A-2007-86219 can be referred to.

<Development accelerator>
For the purpose of improving sensitivity, acid anhydrides, phenols, and organic acids may be added to the upper layer or the lower layer constituting the recording layer.

<Surfactant>
In order to improve the coatability of the recording layer and to expand the stability of the processing with respect to the development conditions, non-printing methods such as those described in Japanese Patent Application Laid-Open Nos. 62-251740 and 3-208514 are proposed. Ionic surfactants, amphoteric surfactants as described in JP-A-59-121044 and JP-A-4-13149, and siloxane compounds as described in European Patent No. 950517 Copolymers of fluorine-containing monomers as described in JP-A-62-170950, JP-A-11-288093, and JP-A-2003-057820 can be added.

  In the case of a multilayer type recording layer, the proportion of the surfactant in the lower layer or the uppermost layer in the total solid content is preferably 0.01 to 15% by weight, more preferably 0.01 to 5.0% by weight. %, More preferably 0.05 to 2.0% by weight.

<Bake-out agent / colorant>
To the recording layer, a printing out agent for obtaining a visible image immediately after heating by exposure, or a dye or pigment as an image coloring agent can be added.

<Plasticizer>
A plasticizer may be added to the recording layer in order to impart flexibility of the coating film.

<Wax>
A compound that lowers the static friction coefficient of the surface may be added to the upper layer of the multi-layer recording layer according to the present invention for the purpose of imparting resistance to scratches. Specifically, it has an ester of a long-chain alkyl carboxylic acid as described in US Pat. No. 6,117,913 or JP-A-2004-12770 previously proposed by the present applicant. A compound etc. can be mentioned.
In the case of a recording layer having a multilayer structure, the proportion of the recording layer in the uppermost layer is preferably 0.1 to 10% by weight, more preferably 0.5 to 5% by weight.

(Recording layer forming method)
The recording layer in the lithographic printing plate precursor according to the invention can be formed by dissolving each component constituting the recording layer in a solvent and applying it.

  In the present invention, it is preferable that the recording layer, as a lower layer and an upper layer, is basically formed of two layers sequentially.

As a method of forming the two layers separately, for example, a method using the difference in solvent solubility between the component contained in the lower layer and the component contained in the uppermost layer, or after applying the uppermost layer, Examples include a method of drying and removing the solvent.
Details of these methods are described in JP-A No. 2002-251003.

  In addition, in order to provide a new function, the uppermost layer and the lower layer may be partly compatible in a range where the effects of the present invention are sufficiently exhibited. In this case, partial compatibility can be achieved by controlling the difference in solvent solubility, the drying rate of the solvent after applying the uppermost layer, and the like.

  The concentration of the above-described components (total solid content including additives) in the recording layer coating solution coated on the support is preferably 1 to 50% by weight.

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.

  In particular, in the multi-layer type recording layer, it is desirable that the top layer coating method is a non-contact type in order to prevent damage to the lower layer when the top 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.

Coating amount after drying of a lower layer component is preferably in the range of 0.5 to 4.0 g / m ^2, more preferably in the range of 0.6 to 2.5 g / m ^2. When it is 0.5 g / m ² or more, printing durability is excellent, and when it is 4.0 g / m ² or less, good image reproducibility and sensitivity are obtained.
The coating amount after drying of the top layer components is preferably in the range of 0.05 to 1.0 g / m ^2, more preferably in the range of 0.08 to 0.7 g / m ^2. With 0.05 g / m ² or more, good developing latitude, scratch resistance can be obtained, good sensitivity can be obtained by a 1.0 g / m ² or less.

The lower layer and the coating amount after drying of the combined top layer, preferably in the range of 0.6~4.0g / m ^2, more preferably in the range of 0.7 to 2.5 g / m ² . When the amount is 0.6 g / m ² or more, good printing durability is obtained, and when the amount is 4.0 g / m ² or less, good image reproducibility and sensitivity are obtained.

[Back coat layer]
The lithographic printing plate precursor of the present invention has a backcoat layer (hereinafter simply referred to as a 0.1 to 5 μm-thickness) containing an organic polymer on the surface opposite to the surface having the recording layer of the support (back surface of the support). May be referred to as a “backcoat layer”).

Also, compared with a linear polyurethane, similarly, due to the high mobility of the graft chain, due to the interaction between the polyurethane of the present invention and the infrared absorbing agent, “ON” in the unexposed part as it is applied, and Since the difference due to “OFF” in the exposed part by infrared becomes more effective, it is considered that the dissolution tolerance is also improved.
Since “ON” and “OFF” are large when an alkali-soluble group coexists, particularly when a specific structure containing an acidic hydroxyl group and / or an acidic secondary amino group coexists, the infrared absorber and these It is assumed that there is a contribution of hydrogen bonding with the acidic group. In addition, due to the high polarity, it is considered that when a sulfonamide group is introduced into the graft copolymer as an alkali-soluble group, the multilayer coating suitability is particularly improved.

Next, the plate making method of the present invention, particularly the developing step will be described in detail.
The processing solution used in the development step (hereinafter also referred to as “developing solution”) is preferably an aqueous solution containing a surfactant and having a pH of 6.0 to 13.5, more preferably an aqueous solution of 8.5 to 10.8. preferable.

Surfactant contributes to the improvement of processability. The surfactant used in the treatment liquid of the present invention may contain any of anionic, nonionic, cationic, and amphoteric.
Anionic surfactants include fatty acid salts, abietic acid salts, hydroxyalkane sulfonates, alkane sulfonates, dialkyl sulfosuccinates, linear alkyl benzene sulfonates, branched alkyl benzene sulfonates, alkyl naphthalene sulfonates. , Alkylphenoxy polyoxyethylene propyl sulfonates, polyoxyethylene alkyl sulfophenyl ether salts, N-methyl-N-oleyl taurine sodium, N-alkyl sulfosuccinic acid monoamide disodium salts, petroleum sulfonates, sulfated castor oil , Sulfated beef tallow oil, fatty acid alkyl ester sulfates, alkyl sulfates, polyoxyethylene alkyl ether sulfates, fatty acid monoglyceride sulfates Tell salt, polyoxyethylene alkylphenyl ether sulfate ester salt, polyoxyethylene styryl phenyl ether sulfate ester salt, alkyl phosphate ester salt, polyoxyethylene alkyl ether phosphate ester salt, polyoxyethylene alkylphenyl ether phosphate ester salt, styrene-anhydrous Partially saponified products of maleic acid copolymer, partially saponified products of olefin-maleic anhydride copolymer, naphthalene sulfonate formalin condensates, aromatic sulfonates, aromatic substituted polyoxyethylene sulfonates, etc. Is mentioned. Among these, dialkyl sulfosuccinates, alkyl sulfate esters, and alkyl naphthalene sulfonates are particularly preferably used.

  The cationic surfactant is not particularly limited, and conventionally known cationic surfactants can be used. Examples thereof include alkylamine salts, quaternary ammonium salts, polyoxyethylene alkylamine salts, and polyethylene polyamine derivatives.

  Nonionic surfactants include polyethylene glycol type higher alcohol ethylene oxide adducts, alkylphenol ethylene oxide adducts, polyethylene glycol adducts of aromatic compounds, fatty acid ethylene oxide adducts, polyhydric alcohol fatty acid ester ethylene oxide adducts, Higher alkylamine ethylene oxide adduct, fatty acid amide ethylene oxide adduct, oil and fat ethylene oxide adduct, polypropylene glycol ethylene oxide adduct, dimethylsiloxane-ethylene oxide block copolymer, dimethylsiloxane- (propylene oxide-ethylene oxide) block copolymer, etc. And polyhydric alcohol glycerol fatty acid ester, pentaerythritol fatty acid ester, Rubitoru and fatty acid esters of sorbitan, fatty acid esters of sucrose, alkyl ethers of polyhydric alcohols, fatty acid amides of alkanolamines.

  In the present invention, ethylene oxide adduct of sorbitol and / or sorbitan fatty acid ester, polypropylene glycol ethylene oxide adduct, dimethylsiloxane-ethylene oxide block copolymer, dimethylsiloxane- (propylene oxide-ethylene oxide) block copolymer, polyhydric alcohol Fatty acid esters are more preferred.

  Moreover, from the viewpoint of stable solubility or turbidity in water, the HLB value is preferably 6 or more, and more preferably 8 or more.

The amphoteric surfactant used in the developer used in the present invention is a compound having an anionic site and a cationic site in the same molecule, as is well known in the field of surfactants. , Amphoteric surfactants such as betaines and amine oxides.
As the amphoteric surfactant that can be used in the developer of the present invention, a compound represented by the following formula <1> and a compound represented by the following formula <2> are preferable.

In formula <1>, R ⁸ represents an alkyl group, R ⁹ and R ¹⁰ each independently represents a hydrogen atom or an alkyl group, R ¹¹ represents an alkylene group, and A represents a carboxylate ion or a sulfonate ion. Represent.
In formula <2>, R ¹⁸ , R ¹⁹ and R ²⁰ each independently represents a hydrogen atom or an alkyl group. However, not all of R ¹⁸ , R ¹⁹ and R ²⁰ are hydrogen atoms.

In the above formula <1>, the alkyl group in R ⁸ , R ⁹ or R ¹⁰ and the alkylene group in R ¹¹ may be linear or branched, and may have a linking group in the chain. In addition, it may further have a substituent. As the linking group, those containing a hetero atom such as an ester bond, an amide bond, or an ether bond are preferable. Moreover, as a substituent, a hydroxyl group, an ethylene oxide group, a phenyl group, an amide group, a halogen atom, etc. are preferable.
In the compound represented by the formula <1>, the total number of carbon atoms of R ^{8 to} R ¹¹ is preferably 8 to 25, and more preferably 11 to 21. Within the above range, the hydrophobic portion is appropriate and the solubility in an aqueous developer is excellent.
It is also possible to increase the solubility of the surfactant in an aqueous developer by adding an organic solvent, for example, a solubilizing agent such as alcohol.

In the above formula <2>, the alkyl group in R ¹⁸ , R ¹⁹ or R ²⁰ may be linear or branched, may have a linking group in the chain, and further has a substituent. You may do it. As the linking group, those containing a hetero atom such as an ester bond, an amide bond, or an ether bond are preferable. Moreover, as a substituent, a hydroxyl group, an ethylene oxide group, a phenyl group, an amide group, a halogen atom, etc. are preferable.
In the compound represented by the formula <2>, the total number of carbon atoms of R ^{18 to} R ²⁰ is preferably 8 to 22, and more preferably 10 to 20. Within the above range, the hydrophobic portion is appropriate and the solubility in an aqueous developer is excellent.

The total carbon number of the amphoteric surfactant may be affected by the material used for the photosensitive layer, particularly the properties of the binder. In the case of a binder having a high degree of hydrophilicity, those having a relatively small total carbon number are preferred, and when the binder used has a low degree of hydrophilicity, those having a large total carbon number tend to be preferred.
Preferred specific examples of the amphoteric surfactant that can be used in the developer of the present invention are shown below, but the present invention is not limited thereto.

As the surfactant used in the treatment liquid of the present invention, an anionic surfactant is preferable, and an anionic surfactant containing a sulfonic acid or a sulfonate is particularly preferable.
Surfactants can be used alone or in combination. The content of the surfactant in the developer is preferably from 0.01 to 10% by weight, more preferably from 0.01 to 5% by weight.

In order to keep the processing solution of the present invention at pH 6 to 13.5, preferably pH 8.5 to 10.8, the presence of carbonate ions and hydrogen carbonate ions as buffering agents makes it possible to use the developer for a long time. In addition, it is possible to suppress pH fluctuations, and it is possible to suppress developability degradation, development residue generation, and the like due to pH fluctuations. In order to allow carbonate ions and hydrogen carbonate ions to be present in the developer, carbonate and hydrogen carbonate may be added to the developer, or by adjusting the pH after adding carbonate or bicarbonate, Ions and bicarbonate ions may be generated. The carbonate and bicarbonate are not particularly limited, but are preferably alkali metal salts. Examples of the alkali metal include lithium, sodium, and potassium, and sodium is particularly preferable. These may be used alone or in combination of two or more.
The pH of the developer is not particularly limited as long as it has a buffering effect, but is preferably in the range of pH 8.5 to 10.8.

  The total amount of carbonate and bicarbonate is preferably 0.3 to 20% by weight, more preferably 0.5 to 10% by weight, and particularly preferably 1 to 5% by weight based on the weight of the aqueous alkali solution. When the total amount is 0.3% by weight or more, developability and processing capacity do not deteriorate, and when it is 20% by weight or less, it becomes difficult to form precipitates and crystals, and further, during the processing of the waste liquid of the developer, and during neutralization It becomes difficult to gel and does not interfere with waste liquid treatment.

  Further, for the purpose of assisting the fine adjustment of the alkali concentration and the dissolution of the non-image area photosensitive layer, another alkali agent such as an organic alkali agent may be supplementarily used together. Examples of the organic alkali agent include monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, triisopropylamine, n-butylamine, monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, Examples thereof include diisopropanolamine, ethyleneimine, ethylenediamine, pyridine, tetramethylammonium hydroxide and the like. These other alkaline agents are used alone or in combination of two or more.

  In addition to the above, the treatment liquid of the present invention may contain a wetting agent, preservative, chelate compound, antifoaming agent, organic acid, organic solvent, inorganic acid, inorganic salt, and the like. However, when a water-soluble polymer compound is added, the plate surface tends to become sticky especially when the treatment liquid is fatigued, so it is preferable not to add it.

  As the wetting agent, ethylene glycol, propylene glycol, triethylene glycol, butylene glycol, hexylene glycol, diethylene glycol, dipropylene glycol, glycerin, trimethylolpropane, diglycerin and the like are preferably used. The wetting agent may be used alone or in combination of two or more. In general, the wetting agent is used in an amount of 0.1 to 5% by weight, based on the total weight of the treatment liquid.

  Preservatives include phenol or derivatives thereof, formalin, imidazole derivatives, sodium dehydroacetate, 4-isothiazolin-3-one derivatives, benzoisothiazolin-3-one, 2-methyl-4-isothiazolin-3-one, benztriazole derivatives Amiding anidine derivatives, quaternary ammonium salts, derivatives of pyridine, quinoline, guanidine, diazine, triazole derivatives, oxazole, oxazine derivatives, nitrobromoalcohol-based 2-bromo-2-nitropropane-1,3-diol, 1 1,1-dibromo-1-nitro-2-ethanol, 1,1-dibromo-1-nitro-2-propanol and the like can be preferably used. It is preferable to use two or more kinds of preservatives in combination so as to be effective against various molds and sterilization. The addition amount of the preservative is an amount that stably exerts an effect on bacteria, mold, yeast, etc., and varies depending on the type of bacteria, mold, yeast, but 0.01 to 4 relative to the treatment liquid. A range of% by weight is preferred.

  Examples of the chelate compound include ethylenediaminetetraacetic acid, potassium salt thereof, sodium salt thereof; diethylenetriaminepentaacetic acid, potassium salt thereof, sodium salt thereof; triethylenetetraminehexaacetic acid, potassium salt thereof, sodium salt thereof, hydroxyethylethylenediaminetriacetic acid Nitrilotriacetic acid, sodium salt; 1-hydroxyethane-1,1-diphosphonic acid, potassium salt, sodium salt; aminotri (methylenephosphonic acid), potassium salt, sodium salt And organic phosphonic acids and phosphonoalkanetricarboxylic acids. Organic amine salts are also effective in place of the sodium and potassium salts of the chelating agents. A chelating agent is selected that is stably present in the treatment liquid composition and does not impair the printability. The addition amount is preferably 0.001 to 1.0% by weight with respect to the treatment liquid.

  As the antifoaming agent, a general silicon-based self-emulsifying type, emulsifying type, nonionic HLB 5 or less compound can be used. Silicon antifoaming agents are preferred. Among them, emulsification dispersion type and solubilization can be used. The content of the antifoaming agent is preferably in the range of 0.001 to 1.0% by weight with respect to the treatment liquid.

  Examples of organic acids include citric acid, acetic acid, succinic acid, malonic acid, salicylic acid, caprylic acid, tartaric acid, malic acid, lactic acid, levulinic acid, p-toluenesulfonic acid, xylenesulfonic acid, phytic acid, and organic phosphonic acid. . The organic acid can also be used in the form of its alkali metal salt or ammonium salt. The content of the organic acid is preferably 0.01 to 0.5% by weight with respect to the treatment liquid.

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

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

  When the organic solvent is insoluble in water, it can be used after being solubilized in water using a surfactant or the like. When the developer contains an organic solvent, the concentration of the solvent is preferably less than 40% by weight from the viewpoint of safety and flammability.

  Examples of inorganic acids and inorganic salts include phosphoric acid, metaphosphoric acid, primary ammonium phosphate, secondary ammonium phosphate, primary sodium phosphate, secondary sodium phosphate, primary potassium phosphate, secondary potassium phosphate, Examples thereof include sodium tripolyphosphate, potassium pyrophosphate, sodium hexametaphosphate, magnesium nitrate, sodium nitrate, potassium nitrate, ammonium nitrate, sodium sulfate, potassium sulfate, ammonium sulfate, sodium sulfite, ammonium sulfite, sodium hydrogen sulfate, nickel sulfate and the like. The content of the inorganic salt is preferably 0.01 to 0.5% by weight based on the total weight of the treatment liquid.

  The development temperature is usually 60 ° C. or lower, preferably about 15 to 40 ° C. In the development processing using an automatic developing machine, the developing solution may be fatigued depending on the processing amount. Therefore, the processing capability may be restored using a replenishing solution or a fresh developing solution. In a normal processing step, alkali development is performed, alkali is removed in a post-water washing step, gum processing is performed in a gumming step, and drying is performed in a drying step, whereas in the present invention, carbonate ions and hydrogen carbonate are used. By using an aqueous solution containing ions and a surfactant, pre-water washing, development, and gumming are simultaneously performed. Therefore, the pre-water washing step is not particularly required, and the drying step can be performed only by using one liquid, and further after performing pre-water washing, development and gumming in one bath. After the development, it is preferable to dry after removing excess processing liquid using a squeeze roller or the like.

  The development process can be preferably carried out by an automatic processor equipped with a rubbing member. As an automatic processor, for example, an automatic processor described in JP-A-2-220061 and JP-A-60-59351, which performs a rubbing process while conveying a lithographic printing plate precursor after image exposure, or a cylinder Examples thereof include an automatic processor described in U.S. Pat. Nos. 5,148,746 and 5,568,768 and British Patent No. 2,277,719, which rubs the lithographic printing plate precursor after image exposure set above while rotating a cylinder. Among these, an automatic processor using a rotating brush roll as the rubbing member is particularly preferable.

The rotating brush roll used in the plate making method of the present invention can be appropriately selected in consideration of the difficulty of scratching the image area and the stiffness of the support of the lithographic printing plate precursor. As the rotating brush roll, a known one formed by planting a brush material on a plastic or metal roll can be used. For example, a metal or plastic in which brush materials are implanted in a row, as described in JP-A-58-159533, JP-A-3-100554, or JP-A-62-167253 A brush roll in which the groove mold material is radially wound around a plastic or metal roll as a core without any gap can be used.
Examples of brush materials include plastic fibers (for example, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyamides such as nylon 6.6 and nylon 6.10, polyacrylics such as polyacrylonitrile and poly (meth) acrylate). , Polyolefin synthetic fibers such as polypropylene and polystyrene). For example, fibers having a hair diameter of 20 to 400 μm and a hair length of 5 to 30 mm can be preferably used.
The outer diameter of the rotating brush roll is preferably 30 to 200 mm, and the peripheral speed at the tip of the brush rubbing the plate surface is preferably 0.1 to 5 m / sec. It is preferable to use a plurality of rotating brush rolls.

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

  It is preferable to provide a drying step continuously or discontinuously after the development step. Drying is performed by hot air, infrared rays, far infrared rays, or the like.

  One example of the structure of an automatic processor suitably used in the plate making method of a lithographic printing plate according to the present invention is schematically shown in FIG. The automatic processor shown in FIG. 1 basically includes a developing unit 6 and a drying unit 10, and the lithographic printing plate precursor 4 is developed and gummed in the developing tank 20 and dried in the drying unit 10.

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

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these.
<Synthesis example>
(Synthesis of macromonomer (MM-10))
In a 1 L three-necked flask equipped with a condenser and a stirrer, 139.55 g of N- (4-sulfamoylphenyl) methacrylamide, 470 g of N, N-dimethylacetamide, thioglycerol (manufactured by Wako Pure Chemical Industries, Ltd.) 15 .70 g was weighed and heated and stirred at 80 ° C. for 1 hour under a nitrogen flow (50 mL / min). To this reaction solution, 1.337 g of V-601 (radical polymerization initiator: manufactured by Wako Pure Chemical Industries, Ltd.) was added and stirred at 80 ° C. for 2 hours. Further, V-601 (radical polymerization) was added to this reaction solution. 1.337 g of a polymerization initiator: Wako Pure Chemical Industries, Ltd.) was added and stirred at 90 ° C. for 2 hours. The reaction solution was cooled to room temperature to obtain the desired product (MM-10). It was confirmed from the NMR spectrum, IR spectrum, and GPC (polystyrene conversion) that it was the target product. MM-10 was used in the next reaction without further purification.
Similarly, MM-1 to 9 and MM-11 to 31 can be synthesized.

(Synthesis example of polyurethane (PU-10))
5. To a 300 mL three-necked flask equipped with a condenser and a stirrer, 80.52 g of the MM-10 reaction solution obtained above and 2,2-bis (hydroxymethyl) propionic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) 86 g was weighed and the reaction solution was 50 ° C. to obtain a uniform solution. Millionate MT (Nippon Polyurethane Industry Co., Ltd.) 14.43 g, 2,4-tolylene diisocyanate (Tokyo Chemical Industry Co., Ltd.) 2.51 g, Neostan U-600 (Nitto Kasei Co., Ltd .: Bismuth Catalyst) 0.13 g was added in this order and reacted at 80 ° C. for 4 hours. The reaction solution was poured into 1.5 L of water to precipitate polyurethane. This was collected by filtration, washed and dried to obtain a binder polymer (PU-10). It was confirmed from the NMR spectrum, IR spectrum, and GPC (polystyrene conversion) that it was the target product.
Similarly, PU-1 to 9 and PU-11 to 87 can be synthesized.

(Examples 1 to 37, Comparative Examples 1 and 2 and Reference Example 1)
(Production of support)
The surface of a JIS A 1050 aluminum sheet was grained with a rotating nylon brush using a pumice-water suspension as an abrasive. The surface roughness (centerline average roughness) at this time was 0.5 μm. After washing with water, a 10% sodium hydroxide aqueous solution was immersed in a solution warmed to 70 ° C., and etching was performed so that the amount of aluminum dissolved was 6 g / m ³ . After washing with water, it was neutralized by immersing in a 30% nitric acid aqueous solution for 1 minute and thoroughly washed with water. After that, electrolytic surface roughening was carried out in a 0.7% nitric acid aqueous solution for 20 seconds using a rectangular wave alternating waveform voltage with an anode voltage of 13 volts and a cathode voltage of 6 volts. After dipping to wash the surface, it was washed with water. The roughened aluminum sheet was subjected to a porous anodic oxide film forming treatment using direct current in a 20% aqueous sulfuric acid solution. Electrolysis was performed at a current density of 5 A / dm ² , and the electrolysis time was adjusted to produce a substrate having an anodic oxide film with a weight of 4.0 g / m ^{2 on} the surface. This substrate was treated for 10 seconds in a vapor chamber saturated at 100 ° C. and 1 atm to prepare a substrate (a) having a sealing rate of 60%. The substrate (a) was treated with a 2.5% by weight aqueous solution of sodium silicate at 30 ° C. for 10 seconds to make the surface hydrophilic, and then the following undercoat solution 1 was applied, and the coating film was dried at 80 ° C. for 15 seconds to be a lithographic plate A printing plate support [A] was obtained. The coating amount of the coating film after drying was 15 mg / m ² .

[Undercoat liquid 1]
-0.3 g of the following copolymer having a molecular weight of 28,000
・ Methanol 100g
・ Water 1g

[Formation of recording layer]
After applying the photosensitive solution I having the following composition to the obtained undercoated support [A] with a wire bar, it is dried in a drying oven at 150 ° C. for 40 seconds to obtain a coating amount of 0.8 g / m ^2. Thus, a lower layer was provided. After providing the lower layer, a photosensitive solution II having the following composition was applied with a wire bar to provide an upper layer. After coating, drying was performed at 150 ° C. for 40 seconds to obtain a positive lithographic printing plate precursor for infrared laser in which the coating amount of the lower layer and the upper layer was 1.0 g / m ² .

(Photosensitive solution I)
・ Polyurethane (compounds listed in Table 1) 3.5g
・ Infrared absorber (compound described in Table 1) 0.25 g
・ Bisphenolsulfone 0.3g
・ Tetrahydrophthalic anhydride 0.4g
0.15 g of a dye in which the counter anion of ethyl violet is 6-hydroxy-β-naphthalenesulfonic acid
・ Fluorine-based surfactant (Megafac F-780) 0.02g
(Dainippon Ink Chemical Co., Ltd.)
・ Γ-Butyrolactone 20g
・ Methyl ethyl ketone 60g
・ 20 g of 1-methoxy-2-propanol

(Photosensitive solution II)
・ Novolak resin 1.7g
(M-cresol / p-cresol / phenol = 3/2/5, Mw 8,000)
・ Infrared absorber (IR dye (1) below) 0.15g
・ The following compound Q 0.35g
・ Fluorosurfactant (Megafac F-780, same as above) 0.03g
・ Tridecafluorooctyl methacrylate / 2-adamantyl acrylate / 2-carboxyethyl methacrylate = 30/50/20, copolymer having a weight average molecular weight of 30,000 0.1 g
・ Acrylic resin (Polymer A below) 0.3g
・ Methyl ethyl ketone 33.0g
・ 6-Methoxy-2-propanol 67.0g

ＰＵ−（ａ）

PU- (a)

  REF-2: N-phenylmaleimide / methacrylamide / methacrylic acid = 45/35/20 (molar ratio) copolymer (weight average molecular weight 50,000)

[Evaluation of printing durability]
A test pattern was drawn on the lithographic printing plate precursor by changing the exposure energy with a Trend setter manufactured by Creo. Thereafter, a development processor DT-2 (diluted to a conductivity of 43 mS / cm) and a Fujifilm PS processor LP940H charged with a development temperature of 30 ° C. and a development time of 12 Development was performed in seconds. This was continuously printed using a printer Lithron manufactured by Komori Corporation. At this time, the number of sheets that can be printed while maintaining a sufficient ink density was measured visually to evaluate the printing durability. The printing durability was shown as a relative value when the printing durability of Comparative Example 1 was 1.0.

[Evaluation of development latitude]
The obtained lithographic printing plate precursor was imaged in a test pattern with a Trendsetter 3244VX manufactured by Creo at a beam intensity of 9 w and a drum rotation speed of 150 rpm. After that, using an alkali developer having the following composition and having a conductivity changed by changing the dilution rate by changing the amount of water, the solution temperature was changed to 30 using a PS processor 900H manufactured by Fuji Film Co., Ltd. Development was performed at a development time of 22 seconds while maintaining the temperature. At this time, the developer having the highest conductivity and the lowest conductivity of the developer in which the image portion was not eluted and the development was successfully performed without contamination and coloring caused by the poorly developed photosensitive layer residual film. The difference was evaluated as development latitude.
The results are shown in Table 1.

[Evaluation of sensitivity]
A test pattern was drawn on the obtained lithographic printing original plate by changing the exposure energy with a Trendsetter 3244VFS manufactured by Creo. Thereafter, in the evaluation of the development latitude, the image portion is not eluted, and the developer having the highest electrical conductivity of the developer that can be satisfactorily developed without being stained or colored due to a poorly developed photosensitive layer residual film; Develop with an alkaline developer having an intermediate (average) conductivity between the lowest one and measure the exposure amount (beam intensity at a drum rotation speed of 160 rpm) that can develop a non-image area with this developer. And sensitivity. The smaller the numerical value, the higher the sensitivity. The results are shown in Table 1.

[Evaluation of shrinkability]
Evaluation similar to the above sensitivity evaluation was performed except that the film was stored for one hour in an environment of 25 ° C. and 70% relative humidity after exposure. Then, by storing the result of the sensitivity evaluation as the sensitivity immediately after the exposure, the degree of decrease in the sensitivity was used as a guideline for the shrinkage. The results are shown in Table 1. In addition, the numerical value of Table 1 represents the sensitivity in 1 hour after exposure, and it is evaluated that the shrinkage is better as the numerical value is closer to the sensitivity immediately after the exposure.

[Evaluation of chemical resistance (chemical resistance)]
The lithographic printing plate precursors of the examples were exposed, developed and printed in the same manner as in the evaluation of printing durability. At this time, each time 5,000 sheets were printed, a process of wiping the plate surface with a cleaner (manufactured by Fuji Film Co., Ltd., multi-cleaner) was added to evaluate chemical resistance. When the printing durability at this time is 95% to 100% of the above-mentioned printing number, 枚 数 is 80% to 95%, △ is 60 to 80%, and 60% or less. X. Even when a process of wiping the printing plate with a cleaner is added, the smaller the change in the printing durability index, the better the chemical resistance. The results are shown in Table 1 below.

[Developer]
・ D sorbit 2.5% by weight
-Sodium hydroxide 0.85% by weight
・ Polyethylene glycol lauryl ether 0.5% by weight
(Weight average molecular weight 1,000)
・ Water 96.15% by weight

  As shown in Table 1, the samples of Examples 2 to 37, Comparative Examples 1 and 2, and Reference Example 1 were prepared in addition to Example 1 by changing the polyurethane and the infrared absorbing dye.

  As shown in Table 1, when the polyurethane is used, it can be seen that the development latitude is greatly improved. In particular, those having an amide structure, phosphoric acid structure, phosphonic acid structure, and sulfonamide structure are excellent not only in development latitude but also in exposure discretion (sensitivity), and particularly those having a sulfonamide structure have good chemical resistance. there were. It was an unexpected effect that the shrinkability was improved by using the polyurethane of the present invention.

<Examples 38 to 67, Comparative Examples 3 to 4>
(Production of support)
Using a JIS A 1050 aluminum plate having a thickness of 0.3 mm, a support [B] was produced by the following treatment.

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

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

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

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

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

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

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

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

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

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

(K) Alkali metal silicate treatment The aluminum support obtained by anodizing treatment was immersed in a treatment layer of a 1 wt% aqueous solution of sodium silicate No. 3 at a temperature of 30 ° C. for 10 seconds to immerse the alkali metal silica. Acid salt treatment (silicate treatment) was performed. Then, the water washing by the spray using well water was performed. The amount of silicate adhering at that time was 3.5 mg / dm ² .

The steps (a) to (k) were performed in order, and the support was prepared so that the etching amount in the step (e) was 3.5 g / m ² .

(Formation of intermediate layer)
On the support [B] produced as described above, the following coating solution for forming an intermediate layer was applied, followed by drying at 80 ° C. for 15 seconds to provide an intermediate layer. The coating amount after drying was 15 mg / m ² .

<Intermediate layer forming coating solution>
・ 0.3 g of the specific polymers listed below
・ Methanol 100g
・ Water 1g

[Formation of recording layer]
Recording layers were prepared in the order of the lower layer and the upper layer using the same photosensitive solution I and photosensitive solution II as in Example 1 on the obtained undercoated support [B]. Note that IR dye (1) (Chemical Formula 25) was used for all infrared absorbers in the photosensitive solution I.

[Evaluation of printing durability after burning]
The plate surface of a lithographic printing plate obtained by developing in the same manner as in the evaluation of printing durability was washed with water and then wiped with a burning surface-conditioning solution BC-7 manufactured by Fuji Film Co., Ltd., followed by burning at about 270 ° C. for 2 minutes. Processed. Then, it washed with water and processed the plate surface with the liquid which diluted the volume FP-2W made from Fuji Film Co., Ltd. with water twice. After that, as with the evaluation of printing durability, printing was performed using a DIC-GEOS (N) black ink manufactured by Dainippon Ink & Chemicals, Inc. on a Lislon printing machine manufactured by Komori Corporation. The printing durability after the burning treatment was evaluated by the number of printed sheets when it was visually recognized that the density began to decrease. The printing durability was shown as a relative value when the printing durability of Comparative Example 3 was 1.0.
The results are shown in Table 2.

  As shown in Table 2, when the polyurethane is used, it can be seen that the development latitude and exposure discrepancy (sensitivity) are greatly improved. Similar to the results in Table 1, those having a sulfonamide structure were excellent in development latitude, exposure discrepancy (sensitivity), and chemical resistance. Further, it was found that when a polyurethane having a thermally crosslinkable group in the side chain was used, the printing durability after the burning treatment was greatly improved.

<Examples 68 to 91, Comparative Examples 7 to 8>
[Preparation of support] [Formation of intermediate layer]
In the same manner as in Example 1, a support and an intermediate layer were prepared.

[Formation of recording layer]
Using the same photosensitive solution I and photosensitive solution II as in Example 1, recording layers were formed in the order of the lower layer and the upper layer. Note that IR dye (1) (Chemical Formula 25) was used for all infrared absorbers in the photosensitive solution I.

(Development process)
Brush roll 1 of an automatic development processor (development tank 25L, plate conveyance speed 100 cm / min, polybutylene terephthalate fiber (hair diameter 200 μm, hair length 17 mm) implanted outer diameter 50 mm) shown in FIG. 1 of the lithographic printing plate precursor after exposure Development was carried out at a temperature of 30 ° C. using a developing solution shown below at 200 revolutions per minute (peripheral speed of the brush tip: 0.52 m / sec) at a drying temperature of 80 ° C. with the same fragrance as the transport direction.

[Developer]
・ Water 8,963.8g
・ 200g sodium carbonate
・ Sodium bicarbonate 100g
・ Surfactant (described in Table 3) 656 g
・ EDTA 4Na 80g
・ 0.1 g of 2-bromo-2-nitropropanediol
・ 0.1g of 2-methyl-4-isothiazolin-3-one
(PH = 9.7)

SU-1: New Coal B4SN (Polyoxyethylene naphthyl ether sulfate manufactured by Nippon Emulsifier Co., Ltd.)
SU-2: Pionein B-111 (Lauryltrimethylammonium chloride, Takemoto Yushi Co., Ltd.)
SU-3: New Coal B13 (Nonionic surfactant manufactured by Nippon Emulsifier Co., Ltd.)

  As can be seen from Table 3, when the polyurethane is used, the development latitude and exposure discrepancy (sensitivity) are greatly improved. Similar to the results in Table 1, those having a sulfonamide structure were excellent in development latitude, exposure discrepancy (sensitivity), and chemical resistance.

  Next, using each processing solution having the following composition, development processing was performed with an automatic developing processor having a structure as shown in FIG. The automatic development processor has a 25 L developing tank, has one brush roll having an outer diameter of 50 mm in which fibers made of polybutylene terephthalate (hair diameter 200 μm, hair length 17 mm) are implanted, 200 revolutions per minute in the same direction (peripheral speed of brush tip 0.52 m / sec). The temperature of the treatment liquid was 30 ° C. The planographic printing plate precursor was transported at a transport speed of 100 cm / min. After the development processing, drying was performed in a drying section. The drying temperature was 80 ° C.

  The obtained lithographic printing plate is attached to a printing machine SOR-M manufactured by Heidelberg, and fountain solution (EU-3 (etch solution manufactured by FUJIFILM Corporation) / water / isopropyl alcohol = 1/89/10 (volume ratio). )) And TRANS-G (N) black ink (manufactured by Dainippon Ink & Chemicals, Inc.), printing was performed at a printing speed of 6,000 sheets per hour.

[Evaluation]
Each lithographic printing plate precursor was evaluated for developability, processability and printing durability as described above.

  From the results shown in the table, the lithographic printing plate precursor according to the present invention has no processing residue in the developing tank in spite of the one-bath treatment with a weakly alkaline developer, and has excellent processability. It can be seen that there is almost no decrease in printing durability due to the plate.

4 Planographic printing plate precursor 6 Developing unit 10 Drying unit 16 Transport roller 20 Developing tank 22 Transport roller 24 Brush roller 26 Squeeze roller 28 Backup roller 36 Guide roller 38 Skewer roller

Claims (10)

On the support,
A lower layer comprising a graft copolymer having an alkali-soluble group;
The upper layer, which increases the solubility in an aqueous alkali solution by exposure, is sequentially laminated,
Infrared absorber is included in lower layer and / or upper layer,
A positive lithographic printing plate precursor for an infrared laser, wherein the graft copolymer in the lower layer is a polyurethane having a structural unit derived from an ethylenically unsaturated monomer as a graft chain.   The positive lithographic printing plate precursor for infrared laser according to claim 1, wherein the polyurethane is a reaction product of diisocyanate and diol.   The positive lithographic printing plate precursor for infrared laser according to claim 1 or 2, wherein the graft chain contains an acidic hydroxyl group and / or an acidic amino group as an alkali-soluble group.   The positive lithographic printing plate precursor for infrared laser according to any one of claims 1 to 3, wherein a terminal of the graft chain is bonded to a diol compound residue via a sulfur atom.   The graft chain contains, as an alkali-soluble group, a group selected from the group consisting of a sulfonamide group, an active imide group, a sulfonic acid group, a phosphoric acid group, and a phosphonic acid group. The positive type lithographic printing plate precursor for infrared laser described in 1.   The positive lithographic printing plate for infrared laser according to any one of claims 1 to 5, wherein the graft chain contains a group selected from the group consisting of a sulfonamide group and an active imide group as an alkali-soluble group. Original edition.   The positive lithographic plate for infrared laser according to claim 2, wherein the diol includes a diol containing a carboxy group and a diol having a graft chain containing a group selected from the group consisting of a sulfonamide group and an active imide group. A printing plate master.   The lithographic printing plate precursor for infrared laser according to any one of claims 1 to 7, wherein the upper layer comprises an infrared absorber. An exposure step for image exposure of the lithographic printing plate precursor according to any one of claims 1 to 8, and
A plate making method of a lithographic printing plate comprising, in this order, a development step of developing using an alkaline aqueous solution having a pH of 8.5 to 10.8.   The lithographic printing plate making method according to claim 9, wherein the alkaline aqueous solution further contains an anionic surfactant or a nonionic surfactant.

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