JPS6224262A - Modifier of lithographic plate - Google Patents

Abstract

PURPOSE:To eliminate only an unnecessary image part by incorporating an o-quinone diazide compd. or a p-diazodiphenylamine compd. contg. an ethylene glycol diacetate to the titled modifier. CONSTITUTION:The titled modifier relates to the modifier for the lithographic plate obtd. by developing the photosensitive lithographic plate contg. the o- quinone diazide compd. or the p-diazodiphenyamine comp. characterized by contg. the ethylene glycol diacetate in the title modifier. The titled modifier is the excellent modifier having a remarkable improvement of an adverse effect for an adjacent image, and having a property of improving a deterioration of a non-oleophilicness, if a burning treatment of an eliminating mark is effected. Thus, the titled modifier having a high workability and a high eliminating rate, without a failure of a plate making, is obtd. The compounding amount of the diethylene glycol diacetate contd. in the title modifier is most preferably 7-40% concentration.

Description

Detailed Description of the Invention (Industrial Field of Application)
The present invention relates to a modifying agent for a lithographic printing plate obtained by developing a photosensitive lithographic printing plate (hereinafter simply referred to as PS plate) containing a socyphenylamine compound, and more specifically, it relates to a correcting agent for an unnecessary image area of a lithographic printing plate. (area that receives printing ink)
It concerns a corrective agent used to erase.

(Prior Art) Lithographic printing plates For example, in lithographic printing plates such as those produced by photolithography, unnecessary images or image areas that need to be deleted or corrected may inevitably occur, making it necessary to correct them. Become. - For example, stains, scratches, cuts, etc. on the original film may cause overexposure or underexposure of the printing plate, resulting in unnecessary image areas that need to be corrected.

As correcting agents for removing unnecessary image areas of such lithographic printing plates, those containing glycol ethers and lactones are disclosed in Japanese Patent Publication Nos. 51-33442 and 55.
-1zx444'y publication. However, in recent years, there has been a high level of technical demand for correction agents, and not only high erasing speeds but also an increase in correction work for minute areas. There has been an even stronger desire for something that has less adverse effects on (necessary image areas that should not be erased). A further drawback of the prior art is that the insensitivity of the erased traces after burning is significantly reduced. Burning is a heat treatment to strengthen the image area after printing, and it is a process that is frequently performed because it greatly increases the number of printing plates that can be printed.
A method for preventing the decrease in hydrophilicity of non-image areas that occurs due to this is disclosed in JP-A-51-143409 and JP-A-52-620.
This method is disclosed in the Japanese Patent Application No. 5, and is generally practiced. However, the erasability of the above-mentioned overexposed and underexposed areas (hereinafter referred to as intermediate tones) is extremely poor, so not only is the erasing speed slow, but even if the above-mentioned method for preventing the decrease in hydrophilicity is applied, the burning causes the insensitivity to disappear. A strong decline in
It becomes easy to accept the development ink build-up and the printing ink during printing, resulting in printing stains.

(Object of the Invention) Therefore, an object of the present invention is to provide a lithographic printing plate corrector that has extremely little adverse effect on adjacent necessary image areas and is capable of erasing only unnecessary image areas.

Another object of the present invention is to provide a lithographic printing plate corrector that does not reduce the insensitivity of erased marks regardless of whether or not burning is performed.

A further object of the present invention is to provide a lithographic printing plate corrector that has a high erasing speed in image areas and a high overall working efficiency.

(Structure of the Invention) As a result of extensive research to achieve the above object, the present inventors have completed the present invention, the gist of which is that it contains ethylene glycol diacetate. , a lithographic printing plate correcting agent obtained by developing a photosensitive lithographic printing plate containing an 0-quinonedimethylamine compound or a p-diazodiphenylamine compound.

The correcting agent of the present invention is superior in that it has significantly improved adverse effects on adjacent lines compared to conventionally known correcting agents, and does not reduce its anti-greasiness even when burned after erasing. Furthermore, from the above, it has been found that the present invention is a highly workable correcting agent with high erasing speed and no failure in plate making.

The present invention will be explained in more detail below.

The purpose of the present invention can be achieved even if the amount of diethylene glycol diacetate contained in the modifier is low, but in practice it should be 2 to 95%, preferably 3 to 80%, based on the total weight of the modifier. used in concentrations. 5 to 60 in order to further improve the performance for the above-mentioned adjacent drawings.
%, most preferably from 7 to 40%.

In the present invention, it is preferable to use an acidic substance in combination,
For example, inorganic acids such as hydrochloric acid, sulfuric acid, persulfuric acid, phosphoric acid, nitric acid, permanganic acid, hydrofluoric acid, citric acid, malic acid, formic acid,
Examples include organic acids such as acetic acid, lactic acid, oxalic acid, trichloroacetic acid, tannic acid, phytic acid, p-)luenesulfonic acid, and phosphonic acid.

Examples of the phosphonic acid include 1-hydroxyethylidene-1,1-diphosphonic acid, 1,2-diphosphono-1,2
-dicarboxyethane, 1,2,2゜3-tetraphosphonopropane, 2(2'-phosphonoethyl fupyridine, methylenephosphonic acid), vinylphosphonic acid,
Mention may be made of polyvinylphosphonic acid, 2-phosphonoethane-1-sulfonic acid, water-soluble copolymers of vinylphosphonic acid with polyacrylic acid and/or vinyl acetate.

Among these acidic substances, phosphoric acid, hydrofluoric acid, acetic acid, trichloroacetic acid, and phosphonic acid are preferred for improving the correction effect, and phosphoric acid and acetic acid are more preferred.

The modifier of the present invention exhibits sufficient performance in an acidic range. Preferably the pH is 0.1-5.L, more preferably 0.15-3, most preferably 0.2-2.L.
The range is 5. These acidic substances can be used alone or in combination of two or more, making it the ultimate corrective agent! ! 0.1-20% by weight based on the amount, preferably 0.3-1o
[It is contained in an amount of 11%, particularly preferably in a range of 0.5 to 6.0% by weight.

The essential function of a correction agent is to remove unnecessary image areas on a printing plate, but in addition to this essential function, how can it improve incidental performance such as bleeding at the boundaries of erased areas and compatibility with washing water? This is also the technique for preparing correction agents. Therefore, it is preferable to further selectively add other organic solvent-based compounds, thickeners, surfactants, water, coloring pigments, etc. to the modifier of the present invention.

These will be explained in detail below.
.

Examples of other organic solvent compounds include ethers, ketones, ketonic acids, ketonic acid esters, lactones, alcohols, fatty acids, and other hydrocarbon solvents.

Typical examples of ethers include glycol ethers, such as methyl ethylene glycol,
Ethylene glycol monoalkyl ethers and ethylene glycol dialkyl ethers of ethyl, isopropyl, and butyl ether, e.g. diethylene glycol monoalkyl ethers and diethylene glycol dialkyl ethers of methyl, ethyl, isopropyl, and isobutyl ether of diethylene glycol, e.g. Methyl-, ethyl- of triethyleneglyfur
, triethylene glycol monoalkyl ethers such as butyl ether, triethylene glycol dialkyl ethers such as ethylene glycol monophenyl (
or tolylphether, propylene glycol monophenyl (or tolylphether, diethylene glycol monophenyl (or tolylphether, diethylene glycol monophenyl (or tolylphether, triethylene glycol monophenyl (or tolyl) ether, tripropylene glycol) monophenyl° (or tolylphether, trimethylene glycol monophenyl (or tolylphether, di-trimethylene glycol monophenyl (or tolylphether, tolylphether) I
J-(Fulkylene glycol monoalkyl ethers such as triethylene glycol monophenyl (or tolyl) ether, etc., such as ethylene glycol monoalkyl ethers such as ethylene glycol monoethyl ether acetate, ethylene glycol monoethyl ether acetate, etc.) There are acetates. Examples of ketones include acetone, methyl ethyl ketone, methyl propyl ketone, methyl isopropyl ketone,
Examples include methylbutylketone, methylamylketone, methylhexylketone, diethyltetone, ethylbutylketone, butylone, diisopropylketone, valerone, mesityl oxide, acetylacetone, acetonylacetone, cyclohexanone, methylcyclohexanone, acetophenone, and the like. Ketone acids include pyruvic acid and benzoylformic acid.

Examples include α-ketonic acids represented by phenylpyruvic acid, β-ketonic acids represented by acetoacetic acid, propionyl acetic acid, benzoyl acetic acid, etc., and γ-ketonic acids represented by levulinic acid and /-benzoylpropionic acid. It will be done. Examples of the ketonic acid ester include methyl, ethyl, propyl, inpropyl, butyl, isobutyl, t-
Examples include alkyl esters such as butyl, yamil, and iso7mil, allyl esters, alkyl esters, alicyclic esters, and the like. Examples of lactones include evabutyrolactone, valerolactone, and hexanolactone. Examples of alcohols include aromatic alcohols, alicyclic flucols, aliphatic alcohols, and polyhydric alcohols. Aromatic alcohols include benzyl alcohol, tolyl carbinol, panillyl alcohol,
Phthalyl alcohol, α- and β-phenylethyl alcohol, α, β-dioxyethylbenzene, 1-7 enyl-1-propanol, 2-7. nil-2-propa7
-ol, 2-phenyl-1-propanol, 3-7enylpropanol, 4-7. Those with saturated aromatic hydrocarbon side chains, such as 7-enylbutanols such as nyl-1-butanol and 4-phenyl-2-butanol, and 1-phenyl-2-propyn-1-ol. , cinnamyl alcohol, etc., where the aromatic hydrocarbon side chain is
□There are those that have unsaturated bonds, and those that have aromatic hydrocarbons further substituted with halogen atoms such as fluorine, bromine, chlorine, and iodine, and substituents such as hydroxyl groups and alkoxy groups. Alicyclic alcohols include, for example, cyclohexanol, cyclopentanol, and terpene alcohols as well as sterins such as lanolin. Aliphatic alcohols include, for example, -yl, butanol, pentanol, hexanol, dimethylfurfur, ethyl alcohol, propanohebutanol, octatool, 7nanol, decanol, undecanol, dodecanol,
Tride 1: Saturated aliphatic-hydric alcohols such as canol, tetradecanol, pentadecanol, hexadecanol, octadecanol, e.g. allyl alcohol,
Unsaturated aliphatic-hydric alcohols include oleyl alcohol, elaidyl alcohol, lylyl alcohol, crunyl alcohol, geraniol, propargyl alcohol, and the like. Polyhydric alcohols include dihydric alcohols such as ethylene glycol and propanediol, trihydric alcohols such as glycerin, and polyhydric alcohols such as diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, and diglycerin. Examples include glycol.

Examples of fatty acids include propionic acid, butyric acid, valeric acid,
caproic acid, enanthic acid, caprylic acid, pelargonic acid,
These include saturated fatty acids such as capric acid, undecylic acid, and lauric acid, and unsaturated fatty acids such as acrylic acid, crotonic acid, undecylic acid, oleic acid, linoleic acid, ricinoleic acid, and sulfuric acid.

Other hydrocarbon solvents, for example, have a boiling point of 12
Petroleum fractions around 0 to 250°C, toluene, xylene, benzene, turpentine, kerosene, lactams such as N-methylpyrrolidone, N.

Various examples include N-dimethylformamide, dimethylsulfoxide, tetrahydrofuran, dioxane, and acetic anhydride.

Among the other organic compounds mentioned above, preferred are glycol ethers, ketones, ketonic acid esters, lactones, aromatic alcohols and other hydrocarbon solvents, which dissolve or swell the image area. have a strong tendency to More preferably, ethylene glycol monoalkyl ethers, diethylene glycol monoalkyl ethers, diethylene glycol dialkyl ethers, methyl ethyl ketone, methyl propyl ketone, diisopropyl ketone, acetylacetone, acetonyl Tk), cyclohexanone, methylcyclohexanone, lactones, benzyl alcohol , α- and β-phenylethyl alcohol, xylene, N-methylpyrrolidone, N
, N-dimethylformamide, dimethyl sulfoxide,
Dioxane, most preferably diethylene glycol dimethyl ether, methyl ethyl ketone, diisopropyl ketone, cyclohexanone, xylene, N.

N-dimethylformamide and lactone dioxane. The organic compounds listed above that can be selectively added can be used alone or in combination of two or more, and are 5 to 85% by weight, preferably 10 to 85% by weight, based on the modifier of the present invention.
It is contained in a range of 70% by weight. As an example of a preferable preparation technique for improving the incidental performance, based on the total weight of the modifier, 5 to 60% by weight of glyfur ethers, 3 to 60% by weight of at least one of ketones and lactones, and 3 to 60% by weight of at least one of ketones and lactones are added. The composition ranges from 5 to 40% by weight of the hydrocarbon solvent. More preferably, glyco-1':I--f
The composition range is 50% by weight of /'HB, 5% to 30% by weight of ketones, and 7% to 25% by weight of the hydrocarbon solvent.

Examples of thickeners include inorganic thickeners such as silicic acid fine powder, modified cellulose such as methyl cellulose, hydroxypropyl methyl cellulose, carboxymethyl cellulose/Ha salt, gum arabic, polyvinylpyrrolidone, polyvinyl methyl ether, polyethylene glycol, and polypropylene glycol. , vinyl methyl ether-maleic anhydride copolymer, and vinyl acetate-maleic anhydride copolymer. Among these, modified cellulose, polyvinylpyrrolidone, and the above-mentioned two types of maleic anhydride copolymers are preferred, and modified cellulose such as hydroxypropyl methylcellulose and polyvinylpyrrolidone are most preferred. The stiff thickener can be used alone or in a mixture of two or more, and the amount added can be changed to achieve the desired viscosity, but it is preferably 0.5 to 25% of the modifier of the present invention. % by weight, more preferably 1-
It is used in a range of 15% by weight.

As surfactants, polyoxyethylene alkyl ethers, polyoxyethylene alkyl 7-phenyl ethers, polyoxyethylene polystyrylphenyl ether, polyoxyethylene polyoxypropylene alkyl ether, glycerin fatty acid partial esters, sorbitan fatty acid partial esters , pentaerythritol fatty acid partial esters, propylene glycol monofatty acid esters, sucrose fatty acid esters, oxyethylene oxypropylene pronocopolymer, polyoxyethylene sorbitan fatty acid partial esters, polyoxyethylene sorbitol fatty acid partial esters, polyethylene glycol Fatty esters, polyglycerin fatty acid partial esters, polyoxyethylenized castor oil, polyoxyethylene glycerin fatty acid partial esters, fatty acid jetanolamides, N,N-bis-2-hydroxyalkylamines, polyoxyethylene Nonionic surfactants such as alkylamines, triethanolamine fatty acid esters, trialkylamine oxides, fatty acid salts, avicenoates, hydroxyalkanesulfonates,
Alkanesulfonates, dialkylsulfosuccinic acid ester salts, linear furkylbenzenesulfonates, branched chain alkylbenzenesulfonates, alkylnaphthalenesulfonates, alkylphenoxypolyoxyethylene propylsulfonates, polyoxyethylene alkylsulfophenyl Ether salts, N-methyl-N-
Sodium oleyl taurine, N-furkylsulfosuccinic acid monosodium salts, petroleum sulfonates, sulfated castor oil, sulfated tallow oil, sulfate ester salts of fatty acid alkyl esters, alkyl sulfate ester salts, polyoxyethylene alkyl ether sulfate Ester salts, fatty acid monoglyceride sulfate ester salts, polyoxyethylene alkylphenyl ether sulfate [f
f, polyoxyethylenestyrylphenyl □Ether sulfate ester salts, alkyl phosphate ester salts,
Polyoxyethylene alkyl ether □Phosphate ester salts, polyoxyethylene alkyl phenyl ether phosphate ester salts, styrene-maleic anhydride °
Partially saponified copolymers, partially saponified olefin-maleic anhydride copolymers, anionic surfactants such as naphthalene sulfonate formalin condensates, furkylamine salts, quaternary ammonium salts, polyoxy Examples include cationic surfactants such as ethylene alkylamine salts and polyethylene polyamine derivatives, and amphoteric surfactants such as carboxybetaines, aminocarboxylic acids, sulfobetaines, aminosulfate esters, and imidacillins. Among the surfactants listed above, polyoxyethylene can also be read as polyoxyalkylene such as polyoxymethylene, polyoxypropylene, and polyoxybutylene. Among these, nonionic surfactants and anionic surfactants are preferred, and surfactants with an HLB of 9 or more are more preferred because each component contained in the modifier mixes well. moreover,
Polyoxyethylene alkyl phenyl ethers, oxyethylene oxypropylene block fuborimers, polyoxyethylene sorbitan fatty acid partial esters, polyoxyethylene sorbitol fatty acid partial esters, polyethylene glycol fatty acid esters, polyglycerin fatty acid partial esters are used as modifiers. This is preferable in order to improve the image area erasing effect. The most preferred is oxyethylene oxypropylene propylene copolymer. It is contained in a range of .5 to 30% by weight, preferably 3 to 20% by weight. 'Water is contained in various components such as acids and is necessarily added, but it can also be added selectively, but in the modifier of the present invention, it has a subtle effect on its performance. . Therefore, the preferable addition amount is 1 to 30% by weight, more preferably 3 to 20% by weight, based on the total weight of the correcting agent.

Coloring pigments can be included when visual contrast is desired, and specifically, dyes such as crystal violet, 7-lanine, brilliant blue, malachite green, and 7-hydrodamine B, as well as inorganic pigments and organic pigments. etc. These colorants are present in an amount of 0.0001 to 0.05% by weight based on the total weight of the correction agent according to the present invention.
, preferably in a range of 0.001 to 0.01% by weight.

The modifier of the present invention contains an 0-quinonediazide compound or a p-diazodiphenylamine compound. p
It is applied to the lithographic printing plate obtained by developing the S plate, and is especially used for correcting and erasing the image area.
- The effects of the present invention are remarkable when applied to a lithographic printing plate obtained by developing a PS plate containing a quinonediazide compound.

These PS versions will be explained in detail below.

Supports for PS plates are dimensionally stable plate-like materials, including those conventionally used as supports for printing plates. Such supports include paper, plastics (e.g. paper laminated with polyethylene, polypropylene, polystyrene, etc.), aluminum plates (including aluminum alloys), zinc plates, copper plates, iron plates, composite metal plates (e.g. chrome Metal plates such as iron plate λ with system coating, such as cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene,
Plastic films such as polystyrene, polypropylene, polycarbonate, polyvinyl acetal, etc., paper or plastic films laminated or vapor-deposited with the above metals, Japanese Patent Publication No. 4B-1832
Composite sheets such as those described in Japanese Patent No. 7, in which an aluminum sheet is bonded to a polyethylene terephthalate film, are included.

The PS plate support used in the present invention has a hydrophilic surface. Here, the term "hydrophilic surface" refers to a surface that becomes wet with dampening water and repels printing ink when a lithographic printing plate is mounted on a printing press and printed under standard conditions.

The surface of the support is preferably subjected to hydrophilic treatment.

There are various methods for hydrophilic treatment. For example, in the case of a support with a plastic surface, methods such as chemical treatment, electric discharge treatment, flame treatment, ultraviolet treatment, high frequency treatment, glow discharge treatment, activated plasma treatment, laser treatment, etc. and undercoating after these treatments are used. There is a method of applying layers. In addition, in the case of a support having a metal surface such as aluminum, graining treatment such as brush polishing and electrolytic polishing, immersion treatment in an aqueous solution of sodium silicate, fluoridated zirconate, phosphate, etc. There are plating, coating, anodizing treatments, etc.

Among the above-mentioned supports, a plate having a grained or anodized aluminum surface, or a chromium-coated iron plate is preferable because it improves the adhesion of the photosensitive layer.

Anodizing baths include hydrochloric acid, nitric acid, chromic acid, boric acid,
Examples include aqueous solutions of various acids such as sulfuric acid, persulfuric acid, phosphoric acid, sulfamic acid, and oxalic acid. An aluminum plate that has been grained and further anodized is more preferred. An aluminum plate that has been brush polished and further anodized, or an aluminum plate that has been brush polished and electrolytically polished and further anodized, has particularly favorable adhesion with the photosensitive layer, so the resulting PS plate has a long printing life. The modifier of the present invention is particularly advantageous because of its high strength. Furthermore, surface roughness is known as one method of expressing the hydrophilicity of a support, and it has been found that this surface roughness also serves as a measure of the adhesiveness of the photosensitive layer. At noon, center line average roughness Ra
[μm] is 0.40 or more, and &'! , 0.
It is preferably 50 or more and 0.80 or less. It shows the most preferable adhesiveness, and the preferable range is 0.60 or more and 0.80 or less. (Measuring instrument: West German Pelten, belt meter,
Tracer RHT 315Qe) It is widely known that a PS plate having a photosensitive composition containing an 0-quinonediazide compound acts in a positive tone, and preferably a 0-quinone diazide compound.
Examples include naphthoquinone diazide compounds. Among the 0-naphthoquinonediazide compounds, in particular, 0-naphthoquinone dicytosulfonic acid esters or O-naphthoquinone dicytocarboxylic acid esters of various hydroxy compounds, and O-naphthoquinonediazide sulfonic acid amides or 0-naphthoquinones of aromatic amino compounds. Dicytocarboxylic acid amides are preferred.

Preferred hydroxy compounds include condensation resins of phenols and carbonyl group-containing compounds. Examples of the phenols include phenol, cresol, resorcinol, and pyrogallol, and examples of the carbonyl group-containing compounds include formaldehyde, benzaldehyde, and acetone. Preferred hydroxyl compounds include phenol-formaldehyde resin, cresol-formaldehyde resin, pyrogallol-acetone resin, and resorcinol-benzaldehyde resin.

Typical specific examples of 0-quinone di7dide compounds include benzoquinone-(1,2)-diazide sulfonic acid or naphthoquinone-(1,2)-diazide sulfonic acid and phenol/formaldehyde resin or cresol/formaldehyde. Esters with resins, esters of naphthoquinone-(1,2)-diazide-(2)-5-sulfonic acid with resorcinol-benzaldehyde resins, described in JP-A-56-1044, U.S. Pat. 635,7
Naphthoquinone (1゜2
)-Ester of diazide sulfonic acid and pyrogallol acetone resin, naphthoquinone-(1,2)-diazide-(2) described in JP-A-55-76346
Examples include esters of -5-sulfonic acid and resorcinol-pyrogallol-77ton co-extractive condensate. For other 0-quinonediazide compounds, JP-A-50-1
A polyester having a hydroxyl group at the end is esterified with 0-su7toquinonedioxytosulfonyl chloride, which is described in Japanese Patent Application Laid-open No. 113305/1983. Like p
- A homopolymer of hydroxystyrene or a copolymer with other copolymerizable monomers subjected to an esterification reaction with 0-naphthoquinone diazide sulfonyl chloride, a bisphenol formaldehyde resin described in Japanese Patent Publication No. 54-29922 and 0-quinonediazide sulfonic acid, U.S. Pat. No. 3,859,0
Alkyl acrylates described in No. 99 specification,
Condensate of copolymer of acroyloxyalkyl carbonate and hydroxyalkyl acrylate with 0-quinonediazide sulfonyl chloride, Japanese Patent Publication No. 49-17
Copolymerization of styrene and phenol derivatives as described in US Pat. No. 481, reaction product of the product with O-quinonediazide sulfonic acid, Copolymers of p-aminostyrene and other copolymerizable monomers with 0-naphthoquinonediazide sulfonic acid or 0-naphthoquinone di7didocarboxylic acid, and polyhydroxybenzophenone and 0-naphthoquinonediazide sulfonyl chloride. These 0-7 toquinone diazide compounds can be used alone, but it is preferable to mix them with an alkali-soluble resin and provide this mixture as a photosensitive layer. Suitable alkali-soluble resins include novolak-type phenolic resins, specifically phenol formaldehyde resins,
Cresol formaldehyde resin, JP-A-55-578
Phenol/cresol formaldehyde copolycondensate resins such as those described in Publication No. 41 are included.

Ru. Furthermore, as described in JP-A-5.0-125806, in addition to the above-mentioned phenol fat-saving resins, phenol substituted with an alkyl group having 3 to 8 carbon atoms such as t-butylphenol formaldehyde resin Or, it is even more preferable to use a condensate of cresol and formaldehyde in combination. The content of the 0-quinonediazide compound is 5 to 80% by weight based on the total solid content of the photosensitive composition.
is preferred, particularly preferably 10 to 50% by weight.

The content of the alkali-soluble resin is preferably 30 to 90% by weight, particularly preferably 5% by weight based on the total solid content of the photosensitive composition.
It is 0 to 85% by weight.

Photosensitive compositions containing p-diazodiphenylamine compounds are widely known as negative PS plates. The negative PS plate contains a photosensitive p-diazodiphenylamine compound and preferably a polymer compound, and is a photosensitive p-diazodiphenylamine compound. Conventionally known nylamine compounds can be used, and preferred are salts of p-diazodiphenylamine resins that are soluble in organic solvents, such as p-diazodiphenylamine resins.
- Salt of diazodiphenylamine and formaldehyde or condensation product of ryohanatoaldehyde or benzaldehyde and hexafluorophosphate, salt with toluenesulfonate, 2
Examples include salts with -hydroxy-4-methoxybenzophenone-5-sulfonate. Examples of polymer compounds include acrylic acid or methacrylic acid copolymers, crotonic acid copolymers, itaconic acid copolymers, maleic acid copolymers, cellulose derivatives having carboxyl groups in their side chains, and carboxyl groups in their side chains. Polyvinyl alcohol derivatives having carboxyl groups, hydroxyalkyl acrylate or methacrylate copolymers having carboxyl groups, unsaturated polyester resins having carboxyl groups, etc. are preferably used. More preferably, it is a polymer compound having an acid value of 10 to 300. Moreover, more preferably, JP-A-50
The following general formula (I
) and a structural unit represented by the following general formula (11), a monomer unit having an aromatic hydroxyl group as described in JP-A-57-192951; A polymer containing a structural unit represented by the general formula (■) is used.

(I) (n) (In the general formula, R' represents a hydrogen atom or a methyl group, R1
represents a hydrogen atom, a methyl group, an ethyl group, or a chloromethyl group, R3 represents a hydrogen atom or a methyl group, and n is 1 to 1
represents an integer of 0] The content of the p-diazodiphenylamine compound in the photosensitive composition according to the present invention is 1 to 70% by weight, preferably 3% by weight.
~60% by weight.

The photosensitive composition as described above can be provided separately into multiple layers, and additives such as dyes, plasticizers, and components imparting printout performance can be added as necessary.

The correcting agent of the present invention is suitably used for positive-working PS plates.

The coating amount of the photosensitive composition provided on the support is 0.
1 to '7 g/m'' is preferable, more preferably 0
．． 5-4 l/m. .

The PS plate thus obtained is exposed through a transparent original to a light source rich in active light, such as a carbon lamp, mercury lamp, metal halide lamp, tungsten lamp, or xenon lamp, and then developed.

The developer used preferably contains at least one of an alkaline agent and an organic solvent, and is selected depending on the type of photosensitive layer. This fact was published in Japanese Unexamined Patent Application Publication No. 59-58
It is described in detail in Japanese Patent No. 431.

As a developing solution for a PS plate containing a p-diazodiphenylamine compound, one containing ethylene glycol monophenyl ether or benzyl alcohol is generally used. As a plate developer, the molar ratio is [Sin, core [y
x] = o, 5 to 1.5 ([5tnt] and [M] respectively indicate the molar concentration of Sin and the molar concentration of total alkali metals such as K, Na, Li, etc., and □
S10. It generally contains 0.8 to 8% by weight.

A PS plate that has been image-exposed with the developer described above □
The method for developing is to apply developer solution 1 from multiple nozzles.
Various conventionally known methods can be used, such as a method of squirting liquid, a method of immersing in a developer, and a method of wiping with a sponge moistened with a developer.

As mentioned above, if there is an unnecessary image area on the lithographic printing plate obtained by subjecting the PS plate to image exposure and development, the image area can be erased by applying the correction agent of the present invention on the image area. Ru.

When the correcting agent of the present invention is applied to the image area of a lithographic printing plate, it is preferable to wash the plate with water after development and use a squeegee to remove the washing water before erasing the plate. A specific method for erasing is to soak a brush in a brush, apply it to the image area, leave it for about 10 seconds to several minutes, or after applying it, rub it lightly with a brush, and then erase it by washing with water overnight. A common method is to wash away the

The lithographic printing plate from which unnecessary image areas have been erased in this way can be used after completing the usual processing steps such as development ink build-up and/or gumming, or after finishing the development ink build-up and/or gum σ [processing is completed after burning]. After that, it is used for printing.

The correcting agent of the present invention is advantageously used because it does not cause deterioration in insensitivity due to burning of erased marks.

The correcting agent of the present invention can quickly erase unnecessary image areas and has extremely little adverse effect on adjacent images, improving the efficiency of plate-making work.

Furthermore, since the correcting agent of the present invention does not reduce its insensitivity even after burning the erased marks, failures caused by plate making and troubles during printing can be eliminated, and the efficiency of plate making and printing is improved.

The present invention will be specifically described below using practical examples, but the present invention is not limited thereto. In addition, in the following examples, "k" represents parts by weight, and "ji" means weight %.

Example 1 A Fluminilum board with a thickness of 0.3 fat was electrochemically roughened in a nitric acid solution, thoroughly washed, and then anodized in a sulfuric acid solution to form an oxide film of 2-5 g/m on the above aluminum. formed on the plate surface.

After washing with water and drying, 3 parts of the esterified product of resorcin benzaldehyde and naphthoquinone 1,2-diazide-5-sulfonyl chloride synthesized according to the example of JP-A-56-1044, 9 parts of cresol-formalin novolak, and Victoria Pure Blue BOH
(A photosensitive solution prepared by dissolving 12 parts of JO (manufactured by Hodogaya Chemical Industry Co., Ltd.) in 100 parts of 2-methoxyethyl alcohol was applied onto the above support using a rotary coater and dried to form a photosensitive layer of 2-89/rrl. A positive PS plate was obtained.

A halftone photographic transparency was densely layered on top of this, and the metal halide lamp used in Example 1 was used at a distance of 0.8 m.
It was exposed to light for seconds and developed with the following developer to obtain a printing plate.

(Developer) Potassium silicate A (Sin, 26%, K, Ol 3.5%) 120 parts 8
6% potassium hydroxide 15.5 parts water
50
After the 0th copy, unnecessary image areas were erased using the correcting agent of the present invention described below, and were completely erased in 40 seconds.

When this printing plate was printed after burning at 250° C. for 8 minutes, the erased marks were not stained at all.

Further, no adverse effects such as staining appeared on the halftone dots that were 0.2 mm close to the erased area.

(Modifier of the present invention) Xylene 5 parts cyclohexanone 20 parts ethylene glycol diacetate 17 parts dimethylformamide 5 parts N-methylpyrrolidone
20 parts hydroxypropyl methyl cellulose 1.8 parts (methoxy groups 28-30%, hydroxypropoxy groups 7-12%, viscosity of 2% aqueous solution at 20°C 4.8-7.2 cpsD. Nopluronic P-85 ( Manufactured by Asahi Denka ■, oxyethylene oxypropylene block copolymer 12 parts 85% phosphoric acid 2.1 parts 99
．． 5% Acetic acid 2 parts Silicic acid fine powder 6.0 parts Water
10 copies (
25° C. pH 0.33) Example 2 When the unnecessary image area of the printing plate obtained in the same manner as in Example 1 was erased using the following correcting agent of the present invention, it was completely erased in 30 seconds. This printing plate was burned in the same manner as in Example 1, and developed ink was applied (28-plate development ink 5PO-1 (IIJ Konishiroku Photo Industry Co., Ltd.). Erased traces such as □ were not smudged at all, and halftone dots close to the erased □ portions were free of smudges up to a distance of about 0.3 m.

(Modifier of the present invention fuxylene 4 parts k
γ-Butyrolactone 15 parts Ethylene glycol diacetate 30 parts Diethylene glycol dimethyl ether 15 parts Silicic acid fine powder 7 parts Hydroxypropyl methyl cellulose 1. sg pluronic P
-8510 parts 85% phosphoric acid 2.1 parts water

11 parts (25°C pH'2.1) Comparative Example 1 JP-A-55-121447 (A corrective agent having the following composition similar to that described in Example 42 was prepared, and a print obtained in the same manner as in Example 1 was prepared. The image area of the plate was erased, burned and inked in the same manner as in Example 2.

It was found that the development ink adhered to the halftone erased traces of the obtained printing plate, resulting in a decrease in oil insensitivity. Furthermore, it was found that the halftone dots close to the erased area were stained with developing ink up to a distance of 1.01111 mm, which had a large adverse effect on the adjacent image.

(Known modifier) δ-valerolactone 29.5 parts Ethylene glycol dimethyl ether 30 parts Solvent naphtha (boiling point 140-200°C) 10 parts Hydroxypropyl methyl cellulose 1.5i (same as Example 1 2 Pluronic P-85 (Example 1) ) 10 parts 85% phosphoric acid
5 parts water
10 parts silicic acid fine powder
5 parts Comparative Example 2 When the unnecessary image part of the printing plate obtained in the same manner as in Example 1 was erased with the following known correction agent, it was erased by 60
Not only did it take several seconds, but when this printing plate was burned in the same manner as in Example 3 and printed on a printing press, printing ink adhered to the erased halftone areas and the printed matter was smeared.

From this, it can be seen that the correcting agent causes a decrease in the insensitivity when the erased traces are burned. In addition, printing stains occurred in the halftone dot area 0.7Jljl close to the erased area,
It has been found that this has a large negative effect on close-up lines.

(Known modifier Noxylene 5 parts N, M-
Dimethylformamide 15 parts Cyclohexanone 30 parts Diethylene glycol monomethyl ether 15 parts Hydroxypropyl methylcellulose 1.8 parts Silicic acid fine powder 6.5 parts Pluronic P-8512 parts 99.5% Acetic acid 2 parts 85%
Phosphoric acid 2.6 parts water
10
Colorant (Food Red No. 1) 0.002 parts Example 3 An aluminum plate with a thickness of 0.24 mm was immersed in a 20% aqueous sodium phosphate solution to degrease it, and then soaked in 0.2 N hydrochloric acid at 5 A/, 1 After electrolytic polishing at a current density of
/ m. Further, the pores were sealed with an aqueous sodium metasilicate solution to obtain a support for a lithographic printing plate. A photosensitive liquid having the following composition was applied to this aluminum plate. Then, it was dried at a temperature of 90°C for 2 minutes to a film thickness of 1 B W/dm.
” and obtained a negative PS version that could be easily erased.

(Photosensitive liquid) Copolymer 5.0 parts □
Diazo 4 fingers 0.5 parts Victoria Pure Blue BOH (manufactured by Odugaya Kagaku) 0.1 parts Methyl cellosolve 100 parts However,
The above copolymer has a weight ratio of p-hydroxyphenyl methacrylamide/acrylonitrile/-ethyl 7 acrylate/methacrylic acid: 8/24159.5/8.5 (
molar ratio) and average molecular weight (Mw) = 5.8
X I O', and the above diazo resin stomach &1p-
'; It is a hexafluorophosphate of a condensate of azophenylamine and paraformaldehyde.

Place the halftone photo/transparent negative on top of this and use the method above.
Exposure was carried out for 50 seconds from a distance of 0.8 m using a Talhalide lamp and Idolfin 2000, and the plate was developed with the following developer to obtain a printing plate.

(Developer) Benzyl alcohol 5.0 parts Sodium carbonate 0.5 parts Sodium sulfite 0.5 parts 3-methyl-3
-Methoxybutanol 26.5 parts water
After 100 copies, unnecessary image areas were erased with the following correction agent of the present invention, and development ink was applied. Erasing was possible in 20 seconds, and no image residue was observed in the intermediate tones. . Furthermore, no adverse effect on adjacent drawing lines occurred up to the vicinity of 0, 111!1.

(Modifier λ of the present invention Ethylene glycol diacetate 20 parts Cyclohexanone 30 parts Diethylene glycol 7 parts Methyl ether 16 parts Xylene 5 parts Hydroxypropyl methyl cellulose 8 parts Pluronic P-
858 parts 55% hydrofluoric acid 0.9 parts 60%
1-hydroxyethylidene-1,1-diphosphonic acid
2.2 parts water
10 parts dye (
Pre-edible IQIJ O,002 parts (pH 1 with pH test paper) Comparative Example 3 The composition of the corrective agent used in Example 6 was the same as that of acidic substances (55% hydrogen fluoride, 60% 1-hydroxyethylidene-1,1- When a correcting agent was prepared except diphosphonic acid) and unnecessary image areas of the printing plate obtained in the same manner as in Example 6 were erased, 5
I could not erase it even after several minutes had passed.

Comparative Example 4 The following correction agent having a composition similar to that described in Japanese Patent Publication No. 46-16047 (Example 6) was prepared, and the image area of the obtained printing plate was erased in the same manner as in Example 6. However, I was unable to delete it.

(Known correction agent)

Claims (1)

[Claims] A lithographic printing plate corrector obtained by developing a photosensitive lithographic printing plate containing an o-quinonediazide-based compound or a p-diazodiphenylamine-based compound, which contains ethylene glycol diacetate.