JP2009265262A - Planographic printing precursor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a planographic printing precursor having good recovering property of restart toning, in particular, an IR light-sensitive positive planographic printing precursor. <P>SOLUTION: The photosensitive planographic printing precursor has an intermediate layer between a substrate and an image recording layer. The substrate is treated with a polymer solution containing a phosphonic acid group or a phosphoric acid group and the intermediate layer contains starch having an onium group. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a lithographic printing original plate, and more particularly to a lithographic printing original plate in which a substrate is pretreated with a polymer having a phosphonic acid group or a phosphoric acid group.

  Conventionally, a lithographic printing original plate (PS plate) having a photosensitive image recording layer is known as a lithographic printing original plate. There are basically two types of PS plates, a negative plate and a positive plate. The negative plate uses a negative film at the time of exposure, and is then developed with a developer for negative plate, and the image recording layer in the unexposed area is removed to form a non-image area. The positive plate uses a positive film at the time of exposure, and is then developed with a positive plate developer, and the image recording layer of the exposed portion solubilized by the exposure is removed to form a non-image portion.

  In recent years, with the advance of computer image processing technology, a method of directly writing an image on an image recording layer by light irradiation corresponding to a digital signal has been developed. A computer-to-plate (CTP) system that uses this system as a lithographic printing original plate and directly forms an image on a photosensitive lithographic printing plate without performing output to a silver salt mask film has attracted attention. A CTP system using a high-power laser having the maximum intensity in the near infrared or infrared region as a light source for light irradiation is capable of obtaining a high-resolution image with a short exposure, and a photosensitive lithographic printing plate used in the system. Has the advantage that it can be handled in a bright room. In particular, solid lasers and semiconductor lasers that emit infrared light with a wavelength of 760 nm to 1200 nm have recently become readily available with high output and small size.

  As a positive photosensitive lithographic printing plate capable of forming an image by developing with a developer after exposure using a solid-state laser or semiconductor laser that emits infrared light, water-insoluble and alkali-soluble Having an image recording layer made of a positive photosensitive composition containing a resin (novolak resin, etc.) and a light-to-heat conversion agent (infrared absorber such as a dye or pigment) and having increased solubility in an alkaline aqueous solution by the action of heat Has been proposed.

  In the lithographic printing original plate, a substrate having a hydrophilic surface is used, but in order to further increase the hydrophilicity, a substrate obtained by hydrophilizing the substrate surface with a polyvinylphosphonic acid treatment or the like is often used. It is known that a lithographic printing plate can be obtained by pretreating a substrate with such a compound so as to obtain a printed matter free from stains during printing. However, these hydrophilized printing plates may cause various stains depending on the materials used (paper, ink, fountain solution, etc.) and printing conditions, and in particular, “restart toning” is prevented. Is required.

  Restart toning refers to smearing when printing is resumed after printing is paused. In a printing site, after a lithographic printing plate is attached to a printing machine and printing is started, printing may be temporarily interrupted during a break such as a lunch break or when an operation that requires stopping the printing machine is performed. At that time, the printing plate is usually left on the printing machine in a state where the ink is adhered to the plate surface, and then printing is usually resumed. When this printing is resumed, stains may occur in the non-image area near the image area, which is referred to as restart toning.

Japanese Patent Laid-Open No. 56-021126 discloses photosensitivity using an aluminum support having a hydrophilic undercoat layer containing at least one hydrophilic resin selected from the group consisting of modified starch and gum arabic to prevent soiling. sex planographic printing original plate is described. However, this document does not describe the restart toning, and does not recognize the restart toning problem of the infrared photosensitive lithographic printing plate.

  Japanese Patent Laid-Open No. 62-097892 discloses a lithographic plate characterized in that a hydrophilic layer containing starch modified with phosphoric acid or a derivative thereof is provided on an aluminum support in order to prevent non-image areas from being stained. The printing original edition is described. However, there is no description regarding restart toning in this document, and there is no recognition about the problem of restart toning of an infrared-sensitive lithographic printing plate.

  JP-A-2003-233168 discloses an intermediate layer containing a polymer having at least a monomer having an onium group as a constituent component on a support subjected to a hydrophilic treatment, and a polymer having at least a carboxyl group. A lithographic printing original plate characterized in that a photosensitive layer comprising a compound, an alkali-soluble resin, and a photosensitive composition containing a compound that absorbs light and generates heat is sequentially provided.

Japanese Patent Laid-Open No. 56-021126 JP-A-62-097892 JP 2003-233168 A

  As a result of intensive studies, the inventors of the present invention have preliminarily treated the lithographic printing plate substrate with a polymer solution having a phosphonic acid group or a phosphoric acid group. It was found that the up (removal) characteristics were inferior and that restart toning was likely to occur.

  An object of the present invention is to provide a lithographic printing original plate having excellent restart toning recovery property, particularly infrared sensitivity, even when the substrate is pretreated with a polymer solution having a phosphonic acid group or a phosphoric acid group. A positive planographic printing original plate is provided.

  In order to achieve the above-mentioned object, the present inventors have further studied earnestly, and have an onium group between a substrate pretreated with a polymer solution having a phosphonic acid group or a phosphoric acid group and the image recording layer. It has been found that the provision of an intermediate layer containing starch significantly reduces restart toning.

  That is, the present invention is a photosensitive lithographic printing original plate having an intermediate layer between a substrate and an image recording layer, wherein the substrate is treated with a polymer solution having a phosphonic acid group or a phosphoric acid group, And the said intermediate | middle layer contains the starch which has an onium group, The photosensitive lithographic printing original plate characterized by the above-mentioned is provided.

  The present invention can provide a photosensitive lithographic printing plate precursor having good restart toning recoverability. Furthermore, the present invention can provide a lithographic printing original plate that can be directly made from digital information such as a computer and has excellent printing stain resistance.

  The lithographic printing plate used in the present invention comprises a substrate, an intermediate layer on the substrate, and an image recording layer.

<Board>
Examples of substrates include metal plates such as aluminum, zinc, copper, stainless steel, and iron; plastic films such as polyethylene terephthalate, polycarbonate, polyvinyl acetal, and polyethylene; papers and plastic films coated with a synthetic resin or a synthetic resin solution And a composite material in which a metal layer is provided by a technique such as vacuum deposition or lamination; and other materials used as a substrate for a printing plate. Among these, it is particularly preferable to use aluminum and a composite substrate coated with aluminum.

  The surface of the aluminum substrate is desirably surface-treated for the purpose of enhancing water retention and improving adhesion with the intermediate layer. Examples of such surface treatment include brush polishing, ball polishing, electrolytic etching, chemical etching, liquid honing, roughening treatment such as sand blasting, and combinations thereof. Among these, a roughening treatment including use of electrolytic etching is particularly preferable.

  As the electrolytic bath used in the electrolytic etching, an aqueous solution containing an acid, an alkali or a salt thereof or an aqueous solution containing an organic solvent is used. Among these, an electrolytic solution containing hydrochloric acid, nitric acid, or a salt thereof is particularly preferable.

  Further, the surface-roughened aluminum substrate is desmutted with an aqueous acid or alkali solution as necessary. The aluminum substrate thus obtained is preferably anodized. In particular, an anodizing treatment in which treatment is performed with a bath containing sulfuric acid or phosphoric acid is desirable.

The substrate used in the present invention is treated with a polymer solution having a phosphonic acid group or a phosphoric acid group after the anodizing treatment.
Examples of the polymer having a phosphonic acid group include a homopolymer of vinylphosphonic acid or a copolymer of vinylphosphonic acid.

Examples of the polymer having a phosphoric acid group include, as monomers, polymers having ethylene glycol acrylate phosphate, ethylene glycol methacrylate phosphate, polyethylene glycol acrylate phosphate, polyethylene glycol methacrylate phosphate, polypropylene glycol acrylate phosphate, polypropylene glycol methacrylate phosphate, and the like. .
These monomers are available under the trade name “Phosmer” and have the following structure:

The polymer used for the substrate treatment preferably further has a carboxylic acid group, and is particularly preferably a copolymer of a monomer having a phosphonic acid group or a phosphoric acid group and (meth) acrylic acid. When a copolymer of a monomer having a phosphonic acid group or a phosphoric acid group and (meth) acrylic acid is used, the monomer ratio of the monomer having a phosphonic acid group or a phosphoric acid group to (meth) acrylic acid is 9: 1 to 1. : The range of 9 is preferable.
These polymers are used as an aqueous solution of 0.01 to 10 g / L. It processes by immersing a board | substrate in this aqueous solution at 20-95 degreeC for 1 to 30 seconds.

<Intermediate layer>
The lithographic printing plate precursor according to the invention has an intermediate layer between the substrate and the image recording layer. The intermediate layer comprises starch having onium groups. This onium group is preferably a quaternary ammonium group in which the positively charged atom in the onium group is selected from a nitrogen atom, a phosphorus atom, or a sulfur atom, and the positively charged atom is a nitrogen atom. It is more preferable that it is a substituent of the following formula.

^{-Z-N + R 1 R 2} R 3 X -

(Wherein R ¹ and R ² each independently represent a C _{1 to} C ₄ alkyl group which may have a substituent; R ³ represents a hydrogen atom or a C which may have a substituent; It represents ₁ -C ₄ alkyl group; X ^- represents a counter anion; Z is as .2 divalent organic group represents a divalent organic group, an aliphatic group, an aromatic group, an alicyclic group, a heterocyclic Shikimoto araliphatic group can be exemplified, as the aliphatic group is preferred. aliphatic groups are particularly suitable alkylene group is preferably a C ₁ -C ₁₀ alkylene group as the alkylene groups, C more preferably ₁ -C ₆ alkylene group, C ₁ -C ₄ alkylene group is particularly preferred. the alkylene group is optionally fluorine, chlorine, bromine, halogen atom such as iodine, C ₁ -C ₄ alkyl group , amino group, mono C ₁ -C ₄ alkyl-substituted amino group, di C ₁ -C ₄ alkyl (It may be substituted with one or more substituents such as a substituted amino group.)

  A starch having an onium group particularly preferred in the present invention is represented by the following formula. Examples of commercially available products include “Excel D-7” (manufactured by Nissho Kagaku), “Petrosize U” (manufactured by Nissho Kagaku), and the like.

(In the above formulas, R, H, or at least ^{one, -Z-N + R 1 R} 2 R 3 X - a, where, R ¹ and R ² are each, independently, substituents have a represents an C ₁ -C ₄ alkyl group, R ³ represents an C ₁ -C ₄ alkyl group which may have a hydrogen atom or a substituent, X ^- is a counter anion, Z is Represents a divalent organic group, and n represents the degree of polymerization.)

  The intermediate layer is usually treated by immersing the substrate in the aqueous starch solution at 20 to 80 ° C. for 1 to 20 seconds.

As a method of providing the intermediate layer on the substrate, it can be applied by various methods other than the above immersion treatment. For example, any method such as bar coater coating, spin coating, spray coating, and curtain coating can be used. The amount of the intermediate layer obtained on the substrate is preferably ^{0.1~100mg / m 2, 1~40mg / m} 2 is particularly preferred.

  In addition to the above components, the intermediate layer can contain, for example, inorganic acids such as sulfuric acid and phosphoric acid, organic acids, polymers containing (meth) acrylic acid, and the like.

<Image recording layer>
The image recording layer constituting the lithographic printing original plate of the present invention can be a single layer, and can be a two-layer system comprising a first image recording layer and a second image recording layer thereon. You can also. The image recording layer can be a layer containing a positive photosensitive composition or a negative photosensitive composition.

As the positive photosensitive composition, it is preferable to use conventionally known positive photosensitive compositions [(a) to (d)] shown below.
(A) Conventionally used conventional positive photosensitive compositions comprising quinonediazide and novolac resin.
(B) An infrared-sensitive positive composition comprising a water-insoluble and alkaline aqueous solution soluble or dispersible resin and a photothermal conversion agent, and having increased solubility in an alkaline aqueous solution by the action of heat.
(C) An infrared photosensitive positive composition comprising a thermally decomposable sulfonic acid ester polymer or acid decomposable carboxylic acid ester polymer and an infrared absorber.
(D) A chemically amplified positive photosensitive composition comprising a combination of an alkali-soluble compound protected with an acid-decomposable group and an acid generator.

As the negative photosensitive composition, conventionally known negative photosensitive compositions ((e) to (h)) shown below can be used.
(E) A negative photosensitive composition comprising a polymer having a photocrosslinkable group and an azide compound.
(F) A negative photosensitive composition comprising a diazo compound.
(G) A photo or thermopolymerizable negative photosensitive composition comprising a photo or thermal polymerization initiator, an addition polymerizable unsaturated compound, and an alkali-soluble polymer compound.
(H) A negative photosensitive composition comprising an alkali-soluble polymer compound, an acid generator, and an acid crosslinkable compound.
In particular, a layer containing an infrared photosensitive positive composition is preferable, and an infrared photosensitive positive lithographic printing original plate composed of a first image recording layer and a second image recording layer is more preferable.

<First image recording layer>
The first image recording layer constituting the lithographic printing original plate contains a resin that is soluble or dispersible in an alkaline aqueous solution.
The resin preferably has at least a functional group such as a hydroxyl group, a carboxyl group, a sulfonic acid group, a phosphoric acid group, an imide group, and an amide group in order to be soluble and dispersible or dispersible in an alkaline aqueous solution. Therefore, a resin that is soluble or dispersible in an alkaline aqueous solution contains one or more ethylenically unsaturated monomers having a functional group such as a hydroxyl group, a carboxyl group, a sulfonic acid group, a phosphoric acid group, an imide group, an amide group, and combinations thereof. It can be suitably produced by polymerizing the monomer mixture.

The ethylenically unsaturated monomer has the following formula:

Wherein R ⁴ is a hydrogen atom, a C _1-22 linear, branched or cyclic alkyl group, a C _1-22 linear, branched or cyclic substituted alkyl group, C _{6- 24} aryl groups or substituted aryl groups, wherein the substituents are selected from C _1-4 alkyl groups, aryl groups, halogen atoms, keto groups, ester groups, alkoxy groups, or cyano groups; X is O, S , and NR is ^5, R ⁵ is hydrogen, straight-chain C _1-22, branched or cyclic alkyl group, a linear, branched or cyclic substituted alkyl group C _1-22, C _{6- 24} aryl groups or substituted aryl groups, wherein the substituents are selected from C _1-4 alkyl groups, aryl groups, halogen atoms, keto groups, ester groups, alkoxy groups, or cyano groups; Y is a single bond, Or C _1-22 linear, branched or cyclic alkylene, alkyleneoxyalkylene, Poly (alkyleneoxy) alkylene, alkylene -NHCONH-; Z is hydrogen, hydroxyl, carboxylic _{acid, -C 6 H 4 -SO 2 NH} 2, -C 6 H 3 -SO 2 NH 2 (-OH) Or the following formula:

または

Or

で表される基である）で表される化合物またはその混合物とすることができる。

Or a mixture thereof.

Examples of the ethylenically unsaturated monomer include, in addition to acrylic acid and methacrylic acid, a compound represented by the following formula and a mixture thereof.

  The monomer mixture can include other ethylenically unsaturated comonomers. Examples of other ethylenically unsaturated comonomers include the following monomers.

  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- Acrylic esters such as hydroxypentyl acrylate, trimethylolpropane monoacrylate, pentaerythritol monoacrylate, glycidyl acrylate, benzyl acrylate, methoxybenzyl acrylate, tetrahydroacrylate;

  Aryl acrylates such as phenyl acrylate, furfuryl acrylate;

  Methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, allyl methacrylate, amyl methacrylate hexyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, chlorobenzyl methacrylate, octyl methacrylate, 4-hydroxybutyl methacrylate, 5-hydroxypentyl methacrylate, 2,2-dimethyl Methacrylic esters such as -3-hydroxypropyl methacrylate, trimethylolpropane monomethacrylate, pentaerythritol monomethacrylate, glycidyl methacrylate, furfuryl methacrylate, tetrahydrofurfuryl methacrylate;

  Aryl methacrylates such as phenyl methacrylate, cresyl methacrylate, naphthyl methacrylate;

N such as N-methylacrylamide, N-ethylacrylamide, N-propylacrylamide, N-butylacrylamide, Nt-butylacrylamide, N-heptylacrylamide, N-octylacrylamide, N-cyclohexylacrylamide, N-benzylacrylamide -Alkyl acrylamides;
N-aryl acrylamides such as N-phenylacrylamide, N-tolylacrylamide, N-nitrophenylacrylamide, N-naphthylacrylamide, N-hydroxyphenylacrylamide;

  N, N-dimethylacrylamide, N, N-diethylacrylamide, N, N-dibutylacrylamide, N, N-di-t-butylacrylamide, N, N-diisobutylacrylamide, N, N-diethylhexylacrylamide, N, N -N, N-dialkylacrylamides such as dicyclohexylacrylamide;

  N, N-arylacrylamides such as N-methyl-N-phenylacrylamide, N-hydroxyethyl-N-methylacrylamide, N-2-acetamidoethyl-N-acetylacrylamide;

N- methyl methacrylamide, N- methacrylamide, N- methacrylamide, N- methacrylamide, N-t-butyl methacrylamide, N- ethylhexyl methacrylamide, N- hydroxyaldehyde methacrylamide, N- cyclohexyl N-alkyl methacrylamides such as methacrylamide;

  N-aryl methacrylamides such as N-phenyl methacrylamide, N-naphthyl methacrylamide;

  N, N-dialkylmethacrylamides such as N, N-diethylmethacrylamide, N, N-dipropylmethacrylamide, N, N-dibutylmethacrylamide;

  N, N-diarylmethacrylamides such as N, N-diphenylmethacrylamide;

  Methacrylamide derivatives such as N-hydroxyethyl-N-methylmethacrylamide, N-methyl-N-phenylmethacrylamide, N-ethyl-N-phenylmethacrylamide;

  Allyl compounds such as 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, ethyl hexyl 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, dimethyl Aminoethyl vinyl ether, diethylaminoethyl vinyl ether, butylaminoethyl 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 anthra Vinyl ethers such as ether;

  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 vinyl esters such as β-phenyl butyrate, vinyl cyclohexyl carboxylate, vinyl benzoate, vinyl salicylate, vinyl chlorobenzoate, vinyl tetrachlorobenzoate, vinyl naphthoate;

  Styrene, methyl styrene, dimethyl styrene, trimethyl styrene, ethyl styrene, diethyl styrene, isopropyl styrene, butyl styrene, hexyl styrene, cyclohexyl styrene, dodecyl styrene, benzyl styrene, chloromethyl styrene, trifluoromethyl styrene, ethoxymethyl styrene, acetoxymethyl Styrene, methoxystyrene, 4-methoxy-3-methylstyrene, dimethoxystyrene, chlorostyrene, dichlorostyrene, trichlorostyrene, tetrachlorostyrene, pentachlorostyrene, bromostyrene, dibromostyrene, iodostyrene, fluorostyrene, 2-bromo- Styrenes such as 4-trifluoromethylstyrene, 4-fluoro-3-trifluoromethylstyrene;

  Crotonic acid esters such as butyl crotonate, hexyl crotonate, crotonic acid, glycerol monocrotonate;

  Dialkyl itaconates such as dimethyl itaconate, diethyl itaconate, dibutyl itaconate;

  Dialkyls of maleic acid or fumaric acid such as dimethyl malate, dibutyl fumarate;

  N-methylmaleimide, N-ethylmaleimide, N-propylmaleimide, N-butylmaleimide, N-phenylmaleimide, N-2-methylphenylmaleimide, N-2,6-diethylphenylmaleimide, N-2-chlorophenylmaleimide, Maleimides such as N-cyclohexylmaleimide, N-laurylmaleimide, N-hydroxyphenylmaleimide;

  Other nitrogen atom-containing monomers such as N-vinylpyrrolidone, N-vinylpyridine, acrylonitrile, methacrylonitrile

  Among these other ethylenically unsaturated comonomers, for example, (meth) acrylic acid esters, (meth) acrylamides, maleimides, and (meth) acrylonitriles are preferably used.

  The content of the resin soluble or dispersible in the alkaline aqueous solution in the first image recording layer is preferably in the range of 20 to 95% by mass with respect to the solid content of the layer. If the content of the resin soluble or dispersible in the alkaline aqueous solution is less than 20% by mass, it is inconvenient in terms of chemical resistance, and if it exceeds 95% by mass, it is not preferable in terms of exposure speed. Moreover, you may use together 2 or more types of resin soluble or dispersible in alkaline aqueous solution as needed.

<Second image recording layer>
The second image recording layer constituting the lithographic printing original plate of the present invention contains an alkali-soluble resin. The alkali-soluble resin that can be used for the second image recording layer is preferably a resin having a carboxylic acid group or an acid anhydride group, and includes a monomer mixture containing an unsaturated carboxylic acid and / or an unsaturated carboxylic acid anhydride. Examples thereof include a copolymer obtained by polymerization and a polyurethane having a substituent containing an acidic hydrogen atom. Examples of the unsaturated carboxylic acid and / or unsaturated carboxylic acid anhydride include acrylic acid, methacrylic acid, maleic acid, maleic anhydride, itaconic acid, and itaconic anhydride. Examples of the copolymerizable ethylenically unsaturated monomer unit include the above-mentioned other ethylenically unsaturated comonomers.
In addition, as the polyurethane having a substituent containing an acidic hydrogen atom, the acidic hydrogen atom includes a carboxyl group, —SO ₂ NHCOO— group, —CONHSO ₂ — group, —CONHSO ₂ NH— group, —NHCONHSO ₂ — group, etc. In particular, an acidic hydrogen atom derived from a carboxyl group is preferred.

  The polyurethane having an acidic hydrogen atom is prepared by, for example, a method of reacting a diol having a carboxyl group with another diol and, if necessary, a diisocyanate; a diol, a diisocyanate having a carboxyl group, and if necessary. A method of reacting with another diisocyanate; or a diol having a carboxyl group, if necessary, another diol, a diisocyanate having a carboxyl group, and another diisocyanate as necessary. It can be synthesized by a reaction method.

  Examples of the diol having a carboxyl group include 3,5-dihydroxybenzoic acid, 2,2-bis (hydroxymethyl) propionic acid, 2,2-bis (hydroxyethyl) propionic acid, and 2,2-bis (3-hydroxypropyl). ) Propionic acid, 2,2-bis (hydroxymethyl) acetic acid, bis- (4-hydroxyphenyl) acetic acid, 4,4-bis- (4-hydroxyphenyl) pentanoic acid, tartaric acid and the like. , 2-bis (hydroxymethyl) propionic acid is more preferred in terms of reactivity with isocyanate.

  Other diols include dimethylolpropane, polypropylene glycol, neopentyl glycol, 1,3-propanediol, polytetramethylene ether glycol, polyester polyol, polymer polyol, polycaprolactone polyol, polycarbonate diol, 1,4-butanediol, Examples include 1,5-pentadiol, 1,6-hexanediol, polybutadiene polyol, and the like.

  Examples of the diisocyanate having a carboxyl group include dimer acid diisocyanate.

  Other diisocyanates include 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate, naphthylene-1,5-diisocyanate, tetramethylxylene diisocyanate, hexamethylene diisocyanate, toluene-2. , 4-diisocyanate, isophorone diisocyanate, hydrogenated xylylene diisocyanate, dicyclohexylmethane diisocyanate, norbornene diisocyanate, trimethylhexamethylene diisocyanate and the like.

  The molar ratio of diisocyanate to diol is preferably 0.7: 1 to 1.5: 1. When an isocyanate group remains at the end of the polymer, the isocyanate group is finally treated by treatment with alcohols or amines. Is synthesized in a form that does not remain.

The mass average molecular weight of the copolymer having an unsaturated carboxylic acid unit and / or an unsaturated carboxylic acid anhydride unit is preferably in the range of 800 to 10,000. When the copolymer having an unsaturated carboxylic acid unit and / or an unsaturated carboxylic acid anhydride unit has a mass average molecular weight of less than 800, the image area obtained by image formation is weak and the developer resistance tends to be inferior. . On the other hand, when the weight average molecular weight of the copolymer having an unsaturated carboxylic acid anhydride unit exceeds 10,000, the sensitivity tends to be inferior.
The mass average molecular weight of the polyurethane having a substituent having an acidic hydrogen atom is preferably in the range of 2,000 to 100,000. When the polyurethane has a mass average molecular weight of less than 2,000, the image area obtained by image formation is weak and tends to have poor printing durability. On the other hand, when the mass average molecular weight of polyurethane exceeds 100,000, the sensitivity tends to be inferior.

The content of the copolymer having an unsaturated carboxylic acid unit and / or an unsaturated carboxylic acid anhydride unit in the second image recording layer is in the range of 10 to 100% by mass relative to the solid content of the layer. preferable. When the content of the copolymer having an unsaturated carboxylic acid unit and / or an unsaturated carboxylic acid anhydride unit is less than 10% by mass, it is disadvantageous in terms of developer resistance and is not preferred.
On the other hand, the content of the copolymer having an unsaturated carboxylic acid unit and / or an unsaturated carboxylic acid anhydride unit or a polyurethane having a substituent having an acidic hydrogen atom is 2 to 90 with respect to the solid content of the layer. A range of mass% is preferred. If the content of the polyurethane having a substituent having an acidic hydrogen atom is less than 2% by mass, it is inconvenient in terms of development speed, and if it exceeds 90% by mass, it is not preferable in terms of storage stability. Moreover, you may use together the polyurethane which has a substituent which has 2 or more types of acidic hydrogen atoms as needed. Furthermore, two or more types of copolymers having unsaturated carboxylic acid anhydride units, copolymers having unsaturated carboxylic acid units, or polyurethanes having a substituent having an acidic hydrogen atom may be used in combination.

<Photothermal conversion material>
The image recording layer can contain a photothermal conversion material. The photothermal conversion material means an arbitrary substance capable of converting electromagnetic waves into heat energy, and a substance having a maximum absorption wavelength in the near infrared to infrared region, specifically, a region having a maximum absorption wavelength of 760 nm to 1200 nm. It is a substance in Examples of such substances include various pigments or dyes.

  Examples of the pigment used in the present invention include commercially available pigments, Color Index Handbook, “Latest Pigment Handbook, Japan Pigment Technology Association, 1977”, “Latest Pigment Applied Technology” (CMC Publishing, 1986), “Printing Ink”. The pigments described in “Technology” (CMC Publishing, 1984) and the like can be used. Examples of the pigment include black pigments, yellow pigments, orange pigments, brown pigments, red pigments, purple pigments, blue pigments, green pigments, fluorescent pigments, and other polymer-bonded pigments. Specifically, insoluble azo pigments, azo lake pigments, condensed azo pigments, chelate azo pigments, phthalocyanine pigments, anthraquinone pigments, perylene and perinone pigments, thioindigo pigments, quinacridone pigments, dioxazine pigments, isoindolinone pigments In addition, quinophthalone pigments, dyed lake pigments, azine pigments, nitroso pigments, nitro pigments, natural pigments, fluorescent pigments, inorganic pigments, carbon black, and the like can be used.

  Among these, carbon black is preferably used as a material that efficiently absorbs light in the near infrared to infrared region and is economically excellent. As such carbon black, grafted carbon black having various functional groups and good dispersibility is commercially available. For example, “Carbon Black Handbook 3rd Edition” (edited by Carbon Black Association, 1995) Pp. 167, “Characteristics of Carbon Black and Optimum Formulation and Utilization Technology” (Technical Information Association, 1997), page 111, and the like can be mentioned, all of which are preferably used in the present invention.

  These pigments may be used without being surface-treated, or may be used after being subjected to a known surface treatment. Known surface treatment methods include methods of surface coating with resins and waxes, methods of attaching surfactants, methods of bonding reactive substances such as silane coupling agents, epoxy compounds, and polyisocyanates to the pigment surface. It is done. These surface treatment methods are described in "Characteristics and Applications of Metal Soap" (Sachi Shobo), "Latest Pigment Application Technology" (CMC Publishing, 1986), "Printing Ink Technology" (CMC Publishing, 1984). ing. The particle size of the pigment used in the present invention is preferably in the range of 0.01 to 15 μm, particularly preferably in the range of 0.01 to 5 μm.

  As the dye used in the present invention, known and commonly used dyes can be used. For example, “Dye Handbook” (edited by the Society of Synthetic Organic Chemistry, published in 1970), “Color Material Engineering Handbook” (edited by Color Material Association, Asakura Shoten) 1989), “Technology and Market of Industrial Dye” (CMC, published in 1983), “Chemical Handbook Applied Chemistry” (The Chemical Society of Japan, Maruzen Shoten, published in 1986). . More specifically, azo dyes, metal chain salt azo dyes, pyrazolone azo dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinoneimine dyes, methine dyes, cyanine dyes, indigo dyes, quinoline dyes, nitro dyes, xanthene dyes And dyes such as thiazine dyes, azine dyes, and oxazine dyes.

  Examples of dyes that efficiently absorb near infrared rays or infrared rays include, for example, azo dyes, metal complex azo dyes, pyrazolone azo dyes, naphthoquinone dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinoneimine dyes, methine dyes, cyanine dyes, Dyes such as squarylium pigments, pyrylium salts, metal thiolate complexes (for example, nickel thiolate complexes) can be used. Among them, cyanine dyes are preferable, and examples include cyanine dyes represented by general formula (I) in JP-A No. 2001-305722 and compounds shown in [0096] to [0103] in JP-A No. 2002-079772. Can do.

As the photothermal conversion material, in particular, the following formula:

（式中、Ｐｈはフェニル基を表す）
を有する染料が好ましい。

(In the formula, Ph represents a phenyl group)
A dye having

  The photothermal conversion material is 0.01 to 50% by mass, preferably 0.1 to 25% by mass, and particularly preferably 1 to 20% by mass with respect to the first and / or second image recording layer. Can be added inside. If the addition amount is less than 0.01% by mass, the sensitivity is lowered, and if it exceeds 50% by mass, the non-image area may be stained during printing. These photothermal conversion materials may be used alone or in combination of two or more.

  In the lithographic printing original plate of the present invention, a solution or dispersion in which the constituents of the image recording layer are dissolved or dispersed in an organic solvent are sequentially applied onto the substrate and dried to form an image recording layer on the substrate. Manufactured by.

  As the organic solvent for dissolving or dispersing the constituent components of the image recording layer, any known conventional solvents can be used. Among them, those having a boiling point in the range of 40 ° C. to 220 ° C., particularly 60 ° C. to 160 ° C. are selected from the advantages in drying.

  Examples of the organic solvent include alcohols such as methyl alcohol, ethyl alcohol, n- or iso-propyl alcohol, n- or iso-butyl alcohol, diacetone alcohol; acetone, methyl ethyl ketone, methyl propyl ketone, methyl butyl ketone, methyl Ketones such as amyl ketone, methyl hexyl ketone, diethyl ketone, diisobutyl ketone, cyclohexanone, methylcyclohexanone, acetylacetone; hydrocarbons such as hexane, cyclohexane, heptane, octane, nonane, decane, benzene, toluene, xylene, methoxybenzene; Acetates such as ethyl acetate, n- or iso-propyl acetate, n- or iso-butyl acetate, ethyl butyl acetate, hexyl acetate; Halides such as tylene dichloride, ethylene dichloride, monochlorobenzene; ethers such as isopropyl ether, n-butyl ether, dioxane, dimethyl dioxane, tetrahydrofuran; ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether , Ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether, ethylene glycol monobutyl ether acetate, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, methoxyethoxyethanol, diethylene glycol monomethyl ether, diethylene glycol dimethyl ether Ether, diethylene glycol methyl ethyl ether, diethylene glycol diethyl ether, propylene glycol, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether, propylene glycol monoethyl ether acetate, propylene glycol monobutyl ether, 3-methyl-3-methoxy Examples include polyhydric alcohols such as butanol and 1-methoxy-2-propanol and derivatives thereof; special solvents such as dimethyl sulfoxide, N, N-dimethylformamide, methyl lactate, ethyl lactate, and γ-butyrolactone. These may be used alone or in combination. And it is suitable that the density | concentration of the solid content in the solution or dispersion liquid to apply | coat is 2-50 mass%. The solid content as used in the field of this invention is a component except a solvent.

Examples of the application method of the component solution or dispersion of the image recording layer include roll coating, dip coating, air knife coating, gravure coating, gravure offset coating, hopper coating, blade coating, wire doctor coating, spray coating, and die coating. Etc. are used. The coating amount is in the range of 10ml / m ² ~100ml / m ² are preferred.

  The solution or dispersion applied on the substrate is usually dried by heated air. The drying temperature (temperature of the heated air) is preferably 30 ° C to 220 ° C, and particularly preferably 40 ° C to 160 ° C. As a drying method, not only a method of keeping the drying temperature constant during drying, but also a method of increasing the drying temperature stepwise can be carried out.

  Moreover, a preferable result may be obtained by dehumidifying the drying air. The heated air is preferably supplied at a rate of 0.1 m / second to 30 m / second, particularly 0.5 m / second to 20 m / second, with respect to the coated surface.

The coating amount of the image recording layer is independently in the range of usually about 0.1 to about 5 g / m ² in terms of dry mass.

<Other components of the image recording layer>
In the image recording layer of the lithographic printing original plate according to the present invention, known additives, for example, coloring materials (dyes, pigments), surfactants, plasticizers, stability improvers, development accelerators, developments, if necessary. Inhibitors, lubricants (silicon powder, etc.) can be added.

  Examples of suitable dyes include basic oil-soluble dyes such as crystal violet, malachite green, Victoria blue, methylene blue, ethyl violet, rhodamine B, and the like. Examples of commercially available products include “Victoria Pure Blue BOH” (manufactured by Hodogaya Chemical Co., Ltd.), “Oil Blue # 603” (manufactured by Orient Chemical Industry Co., Ltd.), “VPB-Naps (Victoria Pure Blue naphthalene sulfonate). "[Hodogaya Chemical Co., Ltd.]", "D11" [PCAS Co., Ltd.] and the like. Examples of the pigment include phthalocyanine blue, phthalocyanine green, dioxazine violet, quinacridone red, and the like.

  Examples of the surfactant include a fluorine-based surfactant and a silicone-based surfactant.

  Examples of the plasticizer include diethyl phthalate, dibutyl phthalate, dioctyl phthalate, tributyl phosphate, trioctyl phosphate, tricresyl phosphate, tri (2-chloroethyl) phosphate, tributyl citrate and the like.

  Furthermore, as a known stability improver, for example, phosphoric acid, phosphorous acid, succinic acid, tartaric acid, malic acid, citric acid, dipicolinic acid, polyacrylic acid, benzenesulfonic acid, toluenesulfonic acid and the like can be used in combination. .

  Examples of other stability improvers include known phenolic compounds, quinones, N-oxide compounds, amine compounds, sulfide group-containing compounds, nitro group-containing compounds, and transition metal compounds. Specifically, hydroquinone, p-methoxyphenol, p-cresol, pyrogallol, t-butylcatechol, benzoquinone, 4,4′-thiobis (3-methyl-6-tert-butylphenol), 2,2′-methylenebis ( 4-methyl-6-tert-butylphenol), 2-mercaptobenzimidazole, N-nitrosophenylhydroxyamine primary cerium salt and the like.

  Examples of the development accelerator include acid anhydrides, phenols, and organic acids. As the acid anhydrides, cyclic acid anhydrides are preferable. Specific examples of cyclic acid anhydrides include phthalic anhydride, tetrahydrophthalic anhydride, and hexahydrophthalic anhydride described in US Pat. No. 4,115,128. Acid, 3,6-endooxy-tetrahydrophthalic anhydride, tetrachlorophthalic anhydride, maleic anhydride, chloromaleic anhydride, α-phenylmaleic anhydride, succinic anhydride, pyromellitic anhydride and the like can be used. Examples of the non-cyclic 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. .

  As a development inhibitor, it forms an interaction with the alkali-soluble resin, substantially reduces the solubility of the alkali-soluble resin in the developer in the unexposed area, and weakens the interaction in the exposed area. Any quaternary ammonium salt, polyethylene glycol compound, or the like is preferably used as long as it can be soluble in the developer. Among the above-mentioned infrared absorbers and colorants, there are compounds that function as a development inhibitor, and these are also preferred. In addition, substances that are thermally decomposable, such as onium salts, o-quinonediazide compounds, aromatic sulfone compounds, aromatic sulfonic acid ester compounds, and that substantially reduce the solubility of alkali-soluble resins when not decomposed. Also mentioned.

  The amount of these various additives to be added varies depending on the purpose, but usually a range of 0 to 30% by mass of the solid content of the image recording layer is preferable.

  In addition, other alkali-soluble or dispersible resins can be used in combination with the image recording layer of the lithographic printing original plate according to the present invention, if necessary. Examples of other alkali-soluble or dispersible resins include copolymers of monomers containing alkali-soluble groups such as acrylic acid, methacrylic acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, and other monomers, Examples thereof include polyester resins and acetal resins.

  The lithographic printing original plate of the present invention may contain a matting agent in the image recording layer for the purpose of improving interleaving paper peelability and improving plate transportability of an automatic plate feeder. Furthermore, in order to prevent the surface of the original plate from being scratched on the image recording layer, a protective layer may be provided on the image recording layer, and a matting agent may be contained in the protective layer.

<Exposure / Development>
The infrared sensitive or heat sensitive lithographic printing original plate of the present invention is a so-called computer-to-plate (CTP) plate that can write an image directly on a plate using a laser based on digital image information from a computer or the like. Can be used.

  As the laser light source used in the present invention, a high-power laser having the maximum intensity from the near infrared to the infrared region is most preferably used. Examples of such a high-power laser having a maximum intensity in the infrared region from the near infrared include various lasers having a maximum intensity in the infrared region from the near infrared of 760 nm to 1200 nm, such as a semiconductor laser and a YAG laser.

  The positive type lithographic printing original plate of the present invention is used for an image forming method in which an image is written on an image recording layer using a laser and then developed to remove a non-image portion by a wet method. That is, the image forming method of the present invention comprises a step of imagewise exposing the lithographic printing original plate of the present invention; and developing the exposed lithographic printing original plate to remove an exposed portion, thereby forming an image portion composed of an image recording layer and a non-image. An image is formed through a step of forming a portion.

  Examples of the developer used for the development treatment include an alkaline aqueous solution (basic aqueous solution). The pH of the alkaline aqueous solution used for the positive lithographic printing original plate of the present invention is preferably low pH (pH 12 or less), specifically, 7 to 12, more preferably 8 to 12, and particularly preferably 10 to 12. .

  Examples of the alkaline agent used in the developer include potassium hydroxide, sodium hydroxide, lithium hydroxide, sodium, potassium or ammonium salts of secondary or tertiary phosphate, sodium metasilicate, potassium silicate, sodium carbonate, Inorganic alkali compounds such as ammonia; monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, n-butylamine, di-n-butylamine, monoethanolamine, diethanolamine, triethanolamine, Organic alkali compounds such as ethyleneimine and ethylenediamine are listed.

  The content of the alkali agent in the developer is preferably in the range of 0.005 to 10% by mass, particularly preferably in the range of 0.05 to 5% by mass. When the content of the alkaline agent in the developer is less than 0.005% by mass, the development tends to be poor. When the content is more than 10% by mass, the image part tends to be eroded during development. Therefore, it is not preferable. Moreover, as an alkaline agent, the alkaline aqueous solution which does not contain silicates, such as sodium silicate and potassium silicate, is preferable.

  An organic solvent can also be added to the developer. Examples of organic solvents that can be added to the developer include ethyl acetate, butyl acetate, amyl acetate, benzyl acetate, ethylene glycol monobutyl acetate, butyl lactate, butyl levulinate, methyl ethyl ketone, ethyl butyl ketone, methyl isobutyl ketone, Examples include cyclohexanone, ethylene glycol monobutyl ether, ethylene glycol monobenzyl ether, ethylene glycol monophenyl ether, benzyl alcohol, methylphenyl carbitol, n-amyl alcohol, methyl amyl alcohol, xylene, methylene dichloride, ethylene dichloride, monochlorobenzene, and the like. It is done. When the organic solvent is added to the developer, the amount of the organic solvent added is preferably 20% by mass or less, and particularly preferably 10% by mass or less.

  Furthermore, in the developer, if necessary, water-soluble sulfites such as lithium sulfite, sodium sulfite, potassium sulfite and magnesium sulfite; hydroxy-aromatic compounds such as alkali-soluble pyrazolone compounds, alkali-soluble thiol compounds and methyl resorcin Water softeners such as polyphosphates and aminopolycarboxylic acids; anionic interfaces such as sodium isopropyl naphthalenesulfonate, sodium n-butylnaphthalenesulfonate, sodium N-methyl-N-pentadecylaminoacetate, sodium lauryl sulfate Various surfactants and various antifoaming agents such as an active agent, a nonionic surfactant, a cationic surfactant, an amphoteric surfactant, and a fluorosurfactant can be added.

  The temperature of the developer is preferably in the range of 15 to 40 ° C., and the immersion time is preferably in the range of 1 to 120 seconds. If necessary, the surface can be rubbed lightly during development.

  The lithographic printing plate after development may be washed with water and then treated with a plate surface protective agent. The treatment with the plate surface protective agent is a so-called desensitizing treatment, and is performed for the purpose of protecting non-image areas, preventing printing stains, protecting from scratches, and the like.

  A water-soluble polymer compound having film-forming properties is added to the plate surface protective agent. Examples of water-soluble polymer compounds include gum arabic, fiber derivatives (carboxymethyl cellulose, carboxyethyl cellulose, methyl cellulose, hydroxypropyl cellulose, etc.) and modified products thereof, polyvinyl alcohol and derivatives thereof, polyvinyl pyrrolidone, polyacrylamide and co-polymers thereof. Polymer, vinyl methyl ether / maleic anhydride copolymer, vinyl acetate / maleic anhydride copolymer, styrene / maleic anhydride copolymer, water-soluble soybean polysaccharide, starch derivative (dextrin, enzymatically decomposed dextrin, hydroxypropylated) Starch enzymatic degradation dextrin, carboxydimethylated starch, phosphorylated starch, cyclo (registered trademark) dextrin, etc.), pullulan and pullulan derivatives, hemicellulose extracted from soybean, etc. And the like. The content of these water-soluble polymers is preferably 0.1 to 30% by mass, particularly preferably 1 to 20% by mass.

  The plate surface protective agent may contain a surfactant. Preferred surfactants are nonionic surfactants and cationic surfactants that do not readily interact with onium groups in starch.

  Examples of nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene polystyryl phenyl ether, polyoxyethylene polyoxypropylene alkyl ether, glycerin fatty acid partial esters, sorbitan fatty acid moieties Esters, pentaerythritol fatty acid partial esters, propylene glycol mono fatty acid esters, sucrose fatty acid partial esters, polyoxyethylene sorbitan fatty acid partial esters, polyoxyethylene sorbitol fatty acid partial esters, polyethylene glycol fatty acid esters, polyglycerin fatty acid moieties Esters, polyoxyethylenated castor oil, polyoxyethylene glycerin fatty acid partial esters, fatty acid dietano Luamides, N, N-bis-2-hydroxyalkylamines, polyoxyethylene alkylamines, triethanolamine fatty acid esters, trialkylamine oxides, polypropylene glycol, trimethylolpropane, glycerin or sorbitol polyoxyethylene or polyoxy Examples include adducts of propylene and acetylene glycols.

  Examples of the cationic surfactant include quaternary ammonium salts such as trimethylbenzylammonium chloride. In addition, anionic surfactants are useful for improving the inking property or coater coating property. Specific examples of the anionic surfactant that can be used in the present invention include, for example, fatty acid salts, abietic acid salts, hydroxyalkanesulfonic acid salts, alkanesulfonic acid salts, dialkylsulfosuccinates, linear alkylbenzenesulfonic acid salts, 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 monoamides Sodium salts, petroleum sulfonates, sulfated castor oil, sulfated beef tallow oil, sulfate esters of fatty acid alkyl esters, alkyl sulfate esters, polyoxyethylene alkyl -Ter sulfate, fatty acid monoglyceride sulfate, polyoxyethylene alkylphenyl ether sulfate, polyoxyethylene styrylphenyl ether sulfate, alkyl phosphate, polyoxyethylene alkyl ether phosphate, polyoxyethylene alkylphenyl Examples thereof include ether phosphate esters, partially saponified styrene-maleic anhydride copolymers, partially saponified olefin-maleic anhydride copolymers, and naphthalene sulfonate formalin condensates. Two or more of these surfactants can be used in combination. The amount of the surfactant used is preferably 0.01 to 20% by mass, particularly preferably 0.1 to 10% by mass, based on the total amount of the plate surface protective agent.

  Further, an organic solvent may be added to the plate surface protective agent in order to improve the image area thickening property. Such solvents include alcohols, ketones, esters and polyhydric alcohols.

  Alcohols include n-hexanol, 2-ethylbutanol, n-heptanol, 2-heptanol, 3-heptanol, 2-octanol, 2-ethylhexanol, 3,5,5-trimethylhexanol, nonanol, n-decanol, Examples include undecanol, n-dodecanol, tetradecanol, heptadecanol, trimethylnonyl alcohol, cyclohexanol, benzyl alcohol, and tetrahydrofurfuryl alcohol.

  Examples of ketones include methyl-n-amyl ketone, methyl-n-hexyl ketone, ethyl-n-butyl ketone, di-n-propyl ketone, diacetone alcohol, and cyclohexanone.

  Esters include: n-amyl acetate, isoamyl acetate, methyl isoamyl acetate, methoxybutyl acetate, benzyl acetate, ethyl lactate, butyl lactate, n-amyl lactate, methyl benzoate, ethyl benzoate, dimethyl phthalate, phthalic acid Examples include diethyl, dibutyl phthalate, di-2-ethylhexyl phthalate, and dioctyl phthalate.

  Polyhydric alcohols and their derivatives include ethylene glycol, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol butyl ether, ethylene glycol dibutyl ether, ethylene glycol isoamyl ether, ethylene glycol monophenyl ether, ethylene glycol monophenyl ether Acetate, ethylene glycol benzyl ether, ethylene glycol monohexyl ether, methoxyethanol, diethylene glycol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol monobutyl ether acetate, diethylene glycol dimethyl Ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, triethylene glycol, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, tetraethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, propylene glycol monoethyl ether, propylene glycol mono Butyl ether, 1-butoxyethoxypropanol, dipropylene glycol, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monobutyl ether, octylene glycol, 2-ethyl-1,3-hexane Diol 1,6-F Sundiol, 2,5-hexanediol, 3,4-hexanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, glycerol, glycerol monoacetate, glycerol triacetate, sorbitol, etc. Can be mentioned.

  Further, an acid may be added to the plate surface protective agent for the purpose of pH adjustment and hydrophilization. For example, examples of the mineral acid include phosphoric acid, nitric acid, sulfuric acid and the like. Examples of the organic acid include citric acid, acetic acid, oxalic acid, phosphonic acid, malonic acid, p-toluenesulfonic acid, tartaric acid, malic acid, lactic acid, levulinic acid, phytic acid, organic phosphonic acid, tannic acid, and succinic acid. . Examples of the inorganic salt include magnesium nitrate and nickel sulfate. You may use together at least 1 sort (s) or 2 or more types, such as a mineral acid, an organic acid, or an inorganic salt. The addition amount is preferably 0.1 to 10% by mass.

  In addition to the above components, a chelating agent may be added to the plate surface protective agent as necessary. Usually, the plate surface protecting agent is commercially available as a concentrated solution, and is used by diluting it with tap water, well water or the like at the time of use. Calcium ions contained in the diluted tap water and well water may adversely affect printing and may cause the printed matter to become dirty. Therefore, the above disadvantages can be eliminated by adding a chelate compound. .

  Examples of such chelating agents include ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, triethylenetetraminehexaacetic acid, hydroxyethylethylenediaminetriacetic acid, nitrilotriacetic acid, 1-hydroxyethane-1,1-diphosphonic acid, aminotri (methylenephosphonic acid) , Ethylenediaminetetra (methylenephosphonic acid), diethylenetriaminepenta (methylenephosphonic acid), triethylenetetraminehexa (methylenephosphonic acid), and hydroxyethylethylenediaminetri (methylenephosphonic acid) acids and their potassium and sodium salts and amines Salt. These chelating agents are selected so that they exist stably in the plate surface protective agent composition and do not impair the printability. The addition amount is preferably 0.01 to 10% by mass with respect to the plate surface protective agent at the time of use.

  In addition, additives such as preservatives and antifoaming agents may be added to the plate surface protective agent. For example, as preservatives, phenol or derivatives thereof, formalin, phenol formalin, imidazole derivatives, sodium dehydroacetate, 4-isothiazolin-3-one derivatives, benzointosoline-3-one, benztriazole derivatives, amiding anidine derivatives, quaternary ammonium Examples thereof include salts, derivatives such as pyridine, quinoline and guanidine, diazine, triazole derivatives, oxazole, oxazine derivatives, nitroalcohol derivatives, benzoic acid or derivatives thereof. A preferable addition amount is an amount that exerts a stable effect on bacteria, molds, yeasts, etc., and varies depending on the types of bacteria, molds, yeasts, but 0.001-1 mass for the plate surface protective agent. % Is preferable, and it is preferable to use two or more preservatives in combination so as to be effective against various molds and sterilization. Moreover, as an antifoamer, a silicon antifoamer is preferable. Among them, emulsification dispersion type and solubilization can be used. The addition amount is preferably in the range of 0.001 to 1% by mass with respect to the plate surface protective agent. After the plate surface protective agent treatment, the planographic printing plate is dried and used as a printing plate for printing.

  Hereinafter, the present invention will be described in more detail based on examples. However, the present invention is not limited to these examples.

Synthesis Example of Substrate Pretreatment Material <Polymer 1> Copolymer of vinylphosphonic acid and methacrylic acid 3650 g of ethyl acetate was placed in a 10 liter flask having a stirrer, a condenser and a dropping device and heated to 70 ° C. 390 g (3.61 mol) of vinylphosphonic acid monomer, 1243 g (14.44 mol) of methacrylic acid monomer and 1000 g of ethyl acetate were mixed. In this monomer mixture, 52 g of AIBN was dissolved. This monomer solution was dropped into the reactor at 70 ° C. over 4 hours. After dropwise addition of the monomer solution, the reaction mixture was held at 70 ° C. for an additional 2 hours and cooled to room temperature. The precipitated white powder was separated by filtration and washed with 1000 g of ethyl acetate.

Substrate preparation <Example 1>
An aluminum plate having a thickness of 0.24 mm was degreased with an aqueous sodium hydroxide solution and electropolished in a 20% hydrochloric acid bath to obtain a grained plate having a center line average roughness (Ra) of 0.5 μm. . Subsequently, it was anodized in a 20% sulfuric acid bath at a current density of 2 A / dm ² to form an oxide film of 2.7 g / m ² , washed with water and dried to obtain an aluminum substrate. The substrate thus obtained was immersed in a 0.5 g / L aqueous solution of polymer 1 heated to 60 ° C. for 10 seconds. Thereafter, the substrate was washed with water. Next, this substrate was immersed in an aqueous solution of quaternary ammonium alkyl etherified starch (“Petrosize U” [manufactured by Nissho Kagaku Co., Ltd.)] at 0.5 g / L at 60 ° C. for 10 seconds. Then, this board | substrate was washed with water and dried, and the board | substrate 1 was obtained.

<Example 2>
An aluminum plate having a thickness of 0.24 mm was degreased with an aqueous sodium hydroxide solution and electropolished in a 20% hydrochloric acid bath to obtain a grained plate having a center line average roughness (Ra) of 0.5 μm. . Subsequently, it was anodized in a 20% sulfuric acid bath at a current density of 2 A / dm ² to form an oxide film of 2.7 g / m ² , washed with water and dried to obtain an aluminum substrate. The substrate thus obtained was immersed in a 0.5 g / L aqueous solution of polymer 1 heated to 60 ° C. for 10 seconds. Thereafter, the substrate was washed with water. Next, this substrate was immersed in an aqueous solution of 3.0 g / L of quaternary ammonium alkyl etherified starch (“Petrosize U” [manufactured by Nissho Kagaku Co., Ltd.]) at 60 ° C. for 10 seconds. Thereafter, this substrate was washed with water and dried to obtain a substrate 2.

<Example 3>
An aluminum plate having a thickness of 0.24 mm was degreased with an aqueous sodium hydroxide solution and electropolished in a 20% hydrochloric acid bath to obtain a grained plate having a center line average roughness (Ra) of 0.5 μm. . Subsequently, it was anodized in a 20% sulfuric acid bath at a current density of 2 A / dm ² to form an oxide film of 2.7 g / m ² , washed with water and dried to obtain an aluminum substrate. The substrate thus obtained was immersed in a 0.5 g / L aqueous solution of polymer 1 heated to 60 ° C. for 10 seconds. Thereafter, the substrate was washed with water. Next, this substrate was immersed in an aqueous solution of 0.5 g / L of quaternary ammonium alkyl etherified starch (“Petrosize J” [manufactured by Nissho Kagaku Co., Ltd.]) at 60 ° C. for 10 seconds. Then, this board | substrate was washed with water and dried, and the board | substrate 3 was obtained.

<Example 4>
An aluminum plate having a thickness of 0.24 mm was degreased with an aqueous sodium hydroxide solution and electropolished in a 20% hydrochloric acid bath to obtain a grained plate having a center line average roughness (Ra) of 0.5 μm. . Subsequently, it was anodized in a 20% sulfuric acid bath at a current density of 2 A / dm ² to form an oxide film of 2.7 g / m ² , washed with water and dried to obtain an aluminum substrate. The substrate thus obtained was immersed in a 0.5 g / L aqueous solution of polymer 1 heated to 60 ° C. for 10 seconds. Thereafter, the substrate was washed with water. Next, the substrate was immersed in an aqueous solution of 3.0 g / L of a quaternary ammonium alkyl etherified starch (“Petrosize J” [manufactured by Nissho Kagaku Co., Ltd.]) at 60 ° C. for 10 seconds. Then, this board | substrate was washed with water and dried, and the board | substrate 4 was obtained.

<Comparative Example 1>
An aluminum plate having a thickness of 0.24 mm was degreased with an aqueous sodium hydroxide solution and electropolished in a 20% hydrochloric acid bath to obtain a grained plate having a center line average roughness (Ra) of 0.5 μm. . Subsequently, it was anodized in a 20% sulfuric acid bath at a current density of 2 A / dm ² to form an oxide film of 2.7 g / m ² , washed with water and dried to obtain an aluminum substrate. The substrate thus obtained was immersed in a 0.5 g / L aqueous solution of polymer 1 heated to 60 ° C. for 10 seconds. Thereafter, this substrate was washed with water and dried to obtain a substrate 5.

<Comparative example 2>
An aluminum plate having a thickness of 0.24 mm was degreased with an aqueous sodium hydroxide solution and electropolished in a 20% hydrochloric acid bath to obtain a grained plate having a center line average roughness (Ra) of 0.5 μm. . Subsequently, it was anodized in a 20% sulfuric acid bath at a current density of 2 A / dm ² to form an oxide film of 2.7 g / m ² , washed with water and dried to obtain an aluminum substrate. The substrate thus obtained was immersed in an aqueous solution of 3.0 g / L of quaternary ammonium alkyl etherified starch (“Petrosize U” [manufactured by Nissho Kagaku Co., Ltd.]) at 60 ° C. for 10 seconds. Thereafter, this substrate was washed with water and dried to obtain a substrate 6.

<Comparative Example 3>
An aluminum plate having a thickness of 0.24 mm was degreased with an aqueous sodium hydroxide solution and electropolished in a 20% hydrochloric acid bath to obtain a grained plate having a center line average roughness (Ra) of 0.5 μm. . Subsequently, it was anodized in a 20% sulfuric acid bath at a current density of 2 A / dm ² to form an oxide film of 2.7 g / m ² , washed with water and dried to obtain an aluminum substrate. The substrate thus obtained was immersed in a 0.5 g / L aqueous solution of polymer 1 heated to 60 ° C. for 10 seconds. Thereafter, the substrate was washed with water. Next, this substrate was immersed in an aqueous solution of hydroxyalkylated starch containing no onium group (“Biostarch LT” [manufactured by Nissho Kagaku Co., Ltd.]) at 3.0 g / L at 60 ° C. for 10 seconds. Thereafter, this substrate was washed with water and dried to obtain a substrate 7.

Synthesis of alkali-soluble resin <resin synthesis example>
In a 10 liter flask having a stirrer, a condenser and a dropping device, 2990 g of dimethylacetamide was placed and heated to 90 ° C. 740.5 g of phenylmaleimide, 1001 g of methacrylamide, 368 g of methacrylic acid, 643 g of acrylonitrile, 203.6 g of Phosmer M (manufactured by Unichemical), 222.5 g of styrene, 10.6 g of AIBN, and 16 g of dimethyl mercaptan are dissolved in 2670 g of dimethylacetamide, and nitrogen is added. This solution was dropped into the reactor over 2 hours in an atmosphere. After completion of dropping, 5.3 g of AIBN was added, the temperature was raised to 100 ° C., and the mixture was further stirred for 4 hours. During that time, 5.3 g of AIBN was added and reacted every other hour.

  After completion of the reaction, heating was stopped and the mixture was cooled to 60 ° C. The reaction solution was dropped into 50 liters of water, and the resulting precipitate was collected by vacuum filtration, washed with water, and vacuum dried at 60 ° C. for 24 hours to obtain Resin 1. The yield was 2873 g (90% yield).

Preparation of First Image Recording Layer Coating Solution An image recording layer coating solution 1 (first image recording layer) of the photosensitive composition shown in Table 1 was prepared.

Preparation of Second Image Recording Layer Coating Solution An image recording layer coating solution 2 (second image recording layer) having the composition shown in Table 2 was prepared.

The photosensitive solution composition prepared as shown in Table 1 was coated on the substrate obtained in Examples and Comparative Examples using the roll coater, and the image recording layer coating solution 1 was applied and dried at 100 ° C. for 2 minutes. 1 image recording layer was obtained. The amount of the dried coating film at this time was 1.5 g / m ² . Subsequently, the image recording layer coating solution 2 prepared as shown in Table 2 was applied on the first image recording layer using a roll coater, and the second image recording layer was applied and dried at 100 ° C. for 2 minutes to form two layers. A lithographic printing plate precursor was obtained. Only the second image recording layer was peeled off with methyl isobutyl ketone, and the dry coating amount of the second image recording layer was determined. The dry coating amount of the second image recording layer was 0.5 g / m ² .

Preparation of Developer A developer was prepared with the composition shown in Table 3. The pH was 11.5 and the conductivity was 12 mS / cm.

The obtained two-layer lithographic printing original plate (substrates 1 to 5) was exposed at 150 mJ / cm ² using PT-R4300 (Dainippon Screen Mfg. Co., Ltd.), and developed with an automatic processor P-1310X (Kodak Graphic). Developed at 30 ° C. for 15 seconds using a developer obtained by diluting developer 1 with water 5 times, and then PF-2 finishing gum (manufactured by Kodak Graphic Communications, plate protection agent) ) Was diluted with a 1: 1.5 dilution to obtain a lithographic printing plate.

<Evaluation method>
The produced lithographic printing plate is printed on a coated paper (Roland 201 printing machine: manufactured by Roland Corporation), coated ink, printing ink (space color / fusion G red: manufactured by Dainippon Ink & Chemicals), and dampening water (NA-108W). Concentration 1%: Dainippon Ink and Chemicals, IPA 1%) was used for printing. The restart toning recoverability was evaluated by the following method.

  First, 1000 sheets were printed, and the printing was stopped with ink on the plate surface. The plate surface was directly heated and heated for 30 minutes, and printing was resumed. Printing was performed until the ink color (dirt) generated at that time was completely removed, and the number of sheets where the color had completely returned (recovered number) was recorded.

ホスホン酸基を有するポリマー溶液で処理した後、オニウム基を有するデンプンを含有する中間層を設けた実施例１〜４は良好な汚れ戻り性を示したのに対し、比較例１〜３は、２００枚印刷後も汚れが回復しなかった。

Examples 1 to 4 provided with an intermediate layer containing starch having an onium group after treatment with a polymer solution having a phosphonic acid group showed good soil return, whereas Comparative Examples 1 to 3 Dirt was not recovered even after printing 200 sheets.

Claims (8)

A photosensitive lithographic printing plate having an intermediate layer between a substrate and an image recording layer,
The photosensitive lithographic printing plate precursor, wherein the substrate is treated with a polymer solution having a phosphonic acid group or a phosphoric acid group, and the intermediate layer contains a starch having an onium group.   2. The lithographic printing plate precursor according to claim 1, wherein the lithographic printing plate is an infrared-sensitive positive lithographic printing plate.   3. The lithographic printing original plate according to claim 2, wherein the lithographic printing original plate is an infrared-sensitive positive lithographic printing original plate comprising a first image recording layer and a second image recording layer formed thereon.   The lithographic printing plate precursor according to any one of claims 1 to 3, wherein the onium group is a quaternary ammonium group. The lithographic printing plate precursor according to claim 4, wherein the starch having a quaternary ammonium group has the following structure.

(In the above formulas, R, H, or at least ^{one, -Z-N + R 1 R} 2 R 3 X - a, where, R ¹ and R ² are each, independently, substituents have a represents an C ₁ -C ₄ alkyl group, R ³ represents an C ₁ -C ₄ alkyl group which may have a hydrogen atom or a substituent, X ^- is a counter anion, Z is (Represents a divalent organic group, n represents the degree of polymerization)   The lithographic printing plate precursor according to any one of claims 1 to 5, wherein the polymer having a phosphonic acid group or a phosphoric acid group further has a carboxylic acid group. A method for making a photosensitive lithographic printing plate precursor according to any one of claims 1 to 6,
Imagewise exposure of the lithographic printing plate,
A method for making a lithographic printing plate precursor, comprising developing with an aqueous solution and processing with a plate surface protection solution.   The plate making method of a lithographic printing plate precursor according to claim 7, wherein the aqueous solution is a silicate-free alkaline aqueous solution.