JPH03213861A - Development processing method for original plate for waterless planographic printing plate - Google Patents

Abstract

PURPOSE:To improve the half tone image reproducibility from a highlight part to a shadow part and to prevent the damage of a silicone rubber layer and the fluctuation in developability by adjusting the volume and pH of the water in a developing soln. CONSTITUTION:The plate surface of the exposed original plate of the waterless planographic printing plate is rubbed and the silicone rubber layer of the image part is removed by using the developing soln. contg.>=90wt.% water and having the pH ranging 5.5 to 9.0. Namely, the developing soln. to be used has substantially >=90wt.% water and is used in the 5.5 to 9.0 pH range of the developing soln. The silicone rubber layer of the image part is removed by using such developing soln. and rubbing the plate surface. However, the photosensitive layer of the unexposed part (image part) is substantially not removed. The silicone rubber layer of the non-image part is substantially kept flawless and the reproducibility from the highlight part to the shadow part is improved. This method is preferable in terms of safely and sanitation and the fluctuation in developability is prevented.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for developing a waterless lithographic printing plate precursor, and more specifically, to reproduction of halftone images from highlight areas to shadow areas. This invention relates to a method for developing a waterless lithographic printing plate precursor, which has excellent properties and is resistant to scratches on the silicone rubber layer, and is preferable from the viewpoint of safety and hygiene.

[Background of the Invention] Various types of waterless lithographic printing plate precursors have been known, including those having a structure in which a photosensitive layer and an ink repellent layer are sequentially coated on a support.

This waterless lithographic printing plate precursor is imagewise exposed and then developed, and the developer used for this is conventionally known to use a hydrocarbon-based organic solvent such as Isopar H or toluene. However, when these hydrocarbon-based organic solvents are used as the developer for the waterless lithographic printing plate precursor, the silicone rubber layer swells during development, so if the silicone rubber layer is rubbed in this state, the silicone rubber layer swells. The silicone rubber layer is scratched, and printing with such a printing plate is therefore likely to cause stains on the printed matter.

In addition, as an aqueous developer, for example, JP-A-1-257847
The publication describes a developer for developing a waterless lithographic printing plate precursor, specifically an alkaline developer containing an organic solvent, a basic compound, and a surfactant that dissolves or swells the unexposed portions of the photosensitive layer. A water-based developer is disclosed. This developer contains a basic substance to prevent the formation of sludge in the developer, but since it is an aqueous developer, it has the advantage of being less likely to damage the silicone rubber layer. However, since this developer is alkaline, the developer is easily fatigued over time or during processing, and has the disadvantage that the finish of the development changes.

Furthermore, JP-A No. 63-280251 discloses that after imagewise exposure of a waterless lithographic printing plate precursor having a photopolymerizable photosensitive layer and a silicone rubber layer, the original is developed with warm water to remove silicone rubber from unexposed areas. Techniques are described for removing both the layer and the photosensitive layer.

In this technology, the photosensitive layer in the unexposed area is water-soluble, so it can be developed with an aqueous developer. However, although the photosensitive layer is photocured in the exposed area, it swells, so it is difficult to use a brush etc. during development. Images tend to be missing when rubbed, and the reproducibility of shadow areas in particular tends to be poor.

Therefore, as a result of various studies on the above-mentioned problems, the inventors of the present invention have decided to adjust the amount and pH of water in the developer of a waterless lithographic printing plate precursor having a photocurable water-insoluble photosensitive layer. This makes it possible to solve the above-mentioned problems, and the present invention has been accomplished based on this point.

[Objective of the Invention] Therefore, the object of the present invention is to provide a method that has excellent halftone image reproducibility from highlight areas to shadow areas, is resistant to scratches on the silicone rubber layer, is preferable from a safety and health perspective, and is free from fluctuations in developability. An object of the present invention is to provide a method for developing a waterless lithographic printing plate precursor.

[Structure of the Invention] The object of the present invention is to provide a method for developing a waterless lithographic printing plate precursor having a photocurable water-insoluble photosensitive layer and a silicone rubber layer sequentially on a support, which contain 90% by weight or more of water. and the surface of the exposed original plate of the waterless lithographic printing plate precursor is rubbed using a developer having a pH in the range of 55 to 9.0 to remove the silicone rubber layer in the image area. This was achieved by a method of developing a lithographic printing plate precursor.

The present invention will be specifically explained below.

The developer used in the method for developing a waterless lithographic printing plate precursor of the present invention contains substantially 90% by weight or more of water, and has a pH of 5.5 to 9.0. Used within the range of Furthermore, the plate surface is rubbed using such a developer to remove the silicone rubber layer in the image area. However, this does not substantially remove the photosensitive layer in the unexposed areas (image areas).

It is more preferable to add a surfactant to this developer.

As the surfactant, anionic surfactants and nonionic surfactants are preferably used.

This anionic surfactant is a higher alcohol (
C, a to C22) Sulfuric ester salts [e.g., sodium salt of lauryl alcohol sulfate, sodium salt of cetyl alcohol sulfate, ammonium salt of lauryl alcohol sulfate, "T-Pole B-8
1" (trade name, manufactured by Shell Chemical Co., Ltd.), sodium chloride alkyl sulfate, etc.), aliphatic alcohol phosphate ester salts (e.g., sodium salt of cetyl alcohol phosphate ester, etc.), alkylaryl sulfonates (
For example, dodecylbenzenesulfonic acid sodium salt, isopropylnaphthalenesulfonic acid sodium salt, sinapthalenedisulfonic acid sodium salt, metanitrobenzenesulfonic acid sodium salt, etc.), sulfonates of alkylamides, sulfonates of dibasic fatty acid esters (For example, sodium sulfosuccinate dioctyl ester, sodium sulfosuccinate dihexyl ester, etc.)
There is. Among these, sulfonate salts are particularly preferably used.

Furthermore, various types of nonionic surfactants can be used.

That is, nonionic surfactants can be broadly classified into polyethylene glycol type and polyhydric alcohol type, and either of these can be used in the present invention, but polyethylene glycol type is most effective. This is a nonionic surfactant.

Among them, ethylene oxide group (-CHaCH20-
), and has three or more HLB values (HLB values are Hydro
A nonionic surfactant having a Lipophile Balance of 5 or more (more preferably 8 to 20) is more preferred.

Furthermore, among nonionic surfactants, those having both an ethylene oxy group and a propylene oxide group are particularly preferred, and among these, those having an HLB value of 8 or more are more preferred.

Preferred examples of the nonionic surfactant used in the present invention include compounds represented by the following general formulas [I] to -numerical formulas [■].

- Formula [1] % formula %) General formula [2] General formula [3] % formula %) General formula [4] General formula [5] General formula [6] HO(C2H40)a-(CsHaO)b-( C2H4
0) CH General formula [7] General formula [8] HO-(CH2C)120) nH -Formula [1] to -Formula [8], R represents a hydrogen atom or a monovalent organic group. The organic group includes, for example, a straight or branched alkyl group which may have a substituent having 1 to 30 carbon atoms (for example, an aryl group such as a phenyl group), and an alkylcarbonyl group in which the alkyl moiety is the above-mentioned alkyl group. and a phenyl group which may have a substituent (for example, a hydroxyl group, an alkyl group as described above, etc.).

a, b, c%m, n, x and y each represent an integer of 1 to 40.

Next, specific examples of the nonionic surfactant used in the present invention will be shown.

Polyethylene glycol, polyoxyethylene lauryl ether, polyoxyethylene nonyl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene behenyl ether, polyoxyethylene polyoxypropylene cetyl ether, polyoxyethylene polyoxypropylene behenyl ether , polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene stearylamine, polyoxyethylene oleylamine, polyoxyethylene stearic acid amide, polyoxyethylene oleic acid amide, polyoxyethylene castor oil, polyoxyethylene abyssalin Ethyl ether, polyoxyethylene lanolin ether, polyoxyethylene monolaurate, polyoxyethylene monostearate, polyoxyethylene glyceryl monooleate, polyoxyethylene glycer monostearate,
Polyoxyethylene propylene glycol monostearate, oxyethylene oxypropylene block polymer, disdecynated phenol polyethylene oxide adduct, tribenzylphenol polyethylene oxide adduct, octylphenol polyoxyethylene polyoxybrobylene adduct, glycerol monostearate, sorbitan monolau These nonionic surfactants, such as polyoxyethylene sorbitan monolaurate,
The seeds may be contained alone or two or more kinds may be used in combination.

The weight average molecular weight of the nonionic surfactant used in the present invention is preferably in the range of 300 to 10,000, preferably 500 to 50.
A range of 00 is particularly preferred.

The amount of surfactant added to the developer is 0.01 to 10% by weight for both anionic surfactant and nonionic surfactant.
If it is less than 0.01% by weight, the effect is weak, and if it exceeds 10% by weight, development is inhibited and good performance cannot be obtained.

Further, an organic solvent may be added to the developer,
It is preferably used within a range that does not dissolve the photosensitive layer.

As a preferable organic solvent used in the present invention, 20°C
The solubility in water is 1% by weight or more, such as methanol, ethanol, n-propanol,
Isopropanol, 3-methoxybutanol, 3-methyl-3-methoxybutanol, tert-butylbutanol, ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol Monophenyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol, diethylene glycol 1,000 methyl ether, diethylene glycol dimethyl ether, diethylene glycol monoethyl ether, diethylene glycol diethyl ether, diethylene glycol monobutyl ether, triethylene glycol, triethylene glycol monomethyl ether, triethylene glycol dimethyl ether , tetraethylene glycol, tetraethylene glycol monomethyl ether, tetraethylene glycol dimethyl ether, propylene glycol monomethyl ether, benzyl alcohol, γ-butyrolactone, β-anilinoethanol, and the like.

An organic acid, an inorganic acid, etc. can be further added to the developer.

A dye may be added to the developer used in the present invention in order to facilitate the discrimination between image areas and non-image areas of the printing plate. Examples of pigments that can be added include Victoria Pure Blue 80H (manufactured by Hodogaya Chemical Co., Ltd.) and Oil Blue "6".
03 (manufactured by Orient Chemical Industry Co., Ltd.), triphenylmethane-based dyes, diphenylmethane-based dyes, and the like.

The following additives can be further added to the developer used in the present invention. For example, JP-A-58-751
Neutral salts such as NaCjl, C1), and Br described in JP-A No. 52, EDT described in JP-A-58-190952
A, Chelating agent such as NTA, JP-A-59-12133
[Co (N)13) 6CJ, C0 described in Publication No. 6
Complexes such as Cf2.6H20, sodium alkylnaphthalenesulfonate described in JP-A-50-51324, N-
Anionic or amphoteric surfactants such as tetradecyl N, N-dihydroxyethyl betaine, U.S. Pat. No. 4,374
, nonionic surfactants such as tetramethyldesynediol described in JP-A-55-95946, and cationic polymers such as quaternary compounds of methyl chloride of p-dimethylaminomethyl polystyrene described in JP-A-55-95946. , ampholytic polymer electrolytes such as the copolymer of vinylbenzyltrimethylammonium chlorite and sodium acrylate described in JP-A-56-142528, JP-A-57-1988
Reducing inorganic salts such as sodium sulfite described in Japanese Patent Publication No. 192952, inorganic lithium compounds such as lithium chloride described in JP-A-58-59444, Japanese Patent Publication No. 50-34442
Organolithium compounds such as lithium benzoate described in JP-A No. 59-75255, organometallic surfactants containing silicon, titanium, etc. described in JP-A-59-75255, organoboron compounds described in JP-A-59-84241, Europe Patent No. TOI
Examples include additives such as quaternary ammonium salts such as tetraalkylammonium oxides described in the OTO specification.

The photosensitive layer used in the present invention includes various diazo resins, but preferably a diazo resin represented by a condensate of p-diazodiphenylamine and formaldehyde, which is water-insoluble and organic solvent-soluble. and preferably Japanese Patent Publication No. 47-1167 and No. 57-4389.
Those that are water-insoluble and soluble in ordinary organic solvents, such as those described in Publication No. 0, etc., are used. Particularly preferred is a diazo resin represented by the following general formula [1].

Numerical formula [I] [wherein 1 2 and R3 represent a hydrogen atom, an alkyl group, or an alkoxy group, and R4 represents a hydrogen atom, an alkyl group, or a phenyl group.

X represents PFa or BF4, and Y represents -NH--S- or -0-. ] Examples of the diazo monomer in the diazo resin used in the present invention include 4-diazo-diphenylamine, l
-Diazo-4-N,N-dimethylaminobenzene,! −
Diazo 4- N, N-diethylaminobenzene, 1-
Diazo-4-N-ethyl-N-hydroxyethylaminobenzene, l-diazo-4-N-methyl-N-hydroxyethylaminobenzene, l-diazo-2,5-jethoxy-4-benzoylaminobenzene, 1- Diazo-4
-N-benzylaminobenzene, l-diazo-4-N,
N-dimethylaminobenzene, 1-diazo-4-morpholinobenzene, 1-diazo-2,5-dimethoxy-4-
p-Tolylmercaptobenzene, 1-diazo-2-ethoxy-4-N, N-dimethylaminobenzene, p-diazodimethylaniline, 1-diazo-2,5-dibutoxy-4-morpholinobenzene, 1-diazo -2,5-jethoxy-4-morpholinobenzene, 1-diazo-2,
5-dimethoxy-4-morpholinobenzene, 1-diazo-2,5-jethoxy-4-p-1-lylmercabutobenzene, l-diazo-4-N-ethyl-N-hydroxyethylaminobenzene, 1-diazo -3-ethoxy-4
-N-methyl-N-hensylaminobenzene, 1-diazo-3-chloro-4-N, N-diethylaminobenzene, 1-diazo-3-methyl-4-pyrrolidinobenzene,
1-Diazo-2-chloro-4-N N-dimethylamino-5-methoxybenzene, 1-diazo-3-methoxy-
4-pyrrolidinobenzene, 3-methoxy-4-diazodiphenylamine, 3-ethoxy-4-diazodiphenylamine, 3-(n-propoxy)-4-diazodiphenylamine, 3-(impropoxy)-4-diazodiphenylamine, etc. Can be mentioned.

Examples of the aldehyde used as a condensing agent with the diazo monomer include formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, isobutyraldehyde, and henzaldehyde.

Furthermore, water-soluble diazo resins can be obtained by using chloride ions, tetrachlorozinc acid, etc. as anions, and boron tetrafluoride, hexafluorophosphoric acid, triisopropylnaphthalenesulfonic acid, 4.4- biphenyldisulfonic acid, 2,5-dimethylbenzenesulfonic acid, 2
By using -nitrobenzenesulfonic acid, 2-methoxy-4-hydroxy-5-benzoyl-benzenesulfonic acid, etc., an organic solvent-soluble diazo resin can be obtained. Particularly preferably, a diazo resin made of hexafluorophosphoric acid is used.

The diazo resin is preferably used in combination with a film-forming resin, particularly a polymer compound having a hydroxyl group. Particularly preferably, the polymer compound includes a copolymer having an aliphatic hydroxyl group in the side chain, such as 2-hydroxyethyl acrylate or 2-hydroxyethyl methacrylate, and another copolymerizable monomer. .

In addition to these, polyvinyl butyral resins, polyurethane resins, polyamide resins, epoxy resins, novolak resins, natural resins, etc. may be added as necessary.

In addition, various polymer compounds can be used as the binder used in combination with the diazonium salt, but preferably
A monomer having an aromatic hydroxyl group as described in Japanese Patent No. 4-98613, such as N-(4-hydroxyphenyl)acrylamide, N-(4-hydroxyphenyl)methacrylamide, (L-1m, or p
- Copolymers of hydroxystyrene, O-, 11-, or p-hydroxyphenyl methacrylate and the like with other monomers, hydroxyethyl acrylate as described in U.S. Pat. No. 4,123,276. Examples include polymers containing hydroxyethyl methacrylate units or hydroxyethyl methacrylate units as main repeating units.

The acrylic acid and methacrylic acid units used here are:
It is preferable to use 10% by weight or less based on the binder resin.

In addition to the above polymers, natural resins such as polyvinyl butyral resin, polyurethane resin, polyamide resin, epoxy resin, novolac resin, shellac, rosin, polyvinyl alcohol, U.S. Pat. No. 3,751,
257, linear polyurethane resins as described in U.S. Pat. No. 3,660.097, phthalated polyvinyl alcohol resins, and epoxy resins condensed from bisphenol A and epichlorohydrin. , cellulose acetate, cellulose acetate phthalate, and other celluloses.

Examples of the alkali-soluble resin include novolac resin, vinyl polymer having a phenolic hydroxyl group, and JP-A-55-5
Examples include condensation resins of polyhydric phenols and aldehydes or ketones described in Japanese Patent No. 7841. Examples of novolac resins include phenol/formaldehyde resin, cresol/formaldehyde resin, and JP-A-5
Phenol-cresol-formaldehyde copolycondensation resin as described in Japanese Patent Application Laid-Open No. 55-127553,
Examples include copolycondensation resins of -substituted phenol and phenol or cresol and formaldehyde.

The diazo resin used in the present invention is used in a mixture with a binder resin, and when the binder resin is taken as 100, the diazo resin is preferably in the range of 30 to 2°O (weight ratio), preferably 50 to 150. More preferably 70-1
The range is 20.

Other dyes, pigments such as pigments, fat-sensitizing agents, plasticizers, surfactants, etc. can be added to these photosensitive compositions. The amount of these additives added is 0.1% to 20% by weight, preferably 0.1% to 20% by weight in the solid content of the photosensitive layer.
It is used in a range of 5% to 10% by weight.

The silicone rubber used in the present invention is a linear organic polymer having a repeating unit represented by the following general formula [1] and having a molecular weight of several thousand to several tens of blades and a hydroxyl group in the main chain or at the end of the main chain. Those containing siloxane as a main component are preferred.

General formula [1] % formula % where n is an integer of 2 or more, R is an alkyl group having 1 to 10 carbon atoms, a halogenated alkyl group, an alkoxyl group, a vinyl group, an aryl group, a silanol group (OI (group)) can be,
Preferably, 60% or more of R is a methyl group. The silanol group (O)I group) may be located either in the main chain or at the end of the main chain, but is preferably located at the end.

The silane coupling agent (or silicone crosslinking agent) used in the present invention includes Rn SiX a -n (wherein, n is an integer of 1 to 3, and R is alkyl, aryl, alkenyl, or a combination thereof). In addition, these groups may have functional groups such as halogen, amine, hydroxy, alkoxy, aryloxy, and thiol.

X is 10) 1, -0R2, -0Ac, -o-N-c,
Represents a substituent such as -cp, -Br, -In2, etc. Here, R2 and R3 represent the same thing as R above, and R2 and R3 may be the same or different, respectively. Moreover, Ac represents an acetyl group. ) is a silane compound represented by

That is, the silicone rubber useful in the present invention is obtained by a condensation reaction between such a silicone base polymer and a silicone crosslinking agent such as those listed above.

Specific examples of the silane coupling agent used in the present invention include )IN [(CH2) 3si (OMe) 3]2
% Vinyltriethoxysilane, CI (CI(2)
3si (OMe) 3, CH35t (OAC) 3
, )Is (C)12) 3si (OMe) s, vinyltris(methylethylketoxime)silane, and the like.

The silicone rubber described above is also available as a commercial product, such as YE-3085 manufactured by Toshiba Silicone Co., Ltd. Other useful silicone rubbers can be produced by reacting the above-mentioned base polymer with a silicone oil having repeating units represented by the following general formula [II], or by reacting a silicone oil in which about 3% of R is a vinyl group. It can also be obtained by addition reaction of silicone with a base polymer or reaction of the silicone oils with each other.

General formula [II] HR (wherein, R has the same meaning as R, which is a substituent of the polymer represented by general formula [1], m is an integer of 2 or more, and n is an integer of 0 or 1 or more. ) In order to obtain silicone rubber by such a crosslinking reaction, the crosslinking reaction is carried out using a catalyst. This catalyst includes tin, zinc, cobalt, lead,
Organic carboxylates of metals such as calcium, manganese, etc.
For example, dibutyltin laurate, tin(II) octoate, cobalt naphthenate, or chloroauric acid may be used.

In order to improve the strength of the silicone rubber and obtain a silicone rubber that can withstand the frictional forces generated during printing operations, fillers can be mixed. Silicone rubber mixed with filler in advance is commercially available as silicone rubber stock or silicone rubber dispersion, and when it is preferable to obtain a silicone rubber film by coating as in the present invention, RTV
Alternatively, a dispersion of LTV silicone rubber is preferably used. An example of this is syt Off 23.5RX-257,5H manufactured by Toray Silicone.
There are silicone rubber dispersions for paper coating such as 237.

In the present invention, it is preferable to use condensation and crosslinking type silicone rubber.

The silicone rubber layer preferably contains a silane coupling agent having an amino group in order to further improve adhesiveness.

Examples of preferable silane coupling agents include the following.

(a) 82NC)12c82NH(CH2) 3s
i (OCI(3) 3(,b) H2NCE2
NH(CI(2) ssi(QC)I312(CI
43)(C)H2N((:R2)351 (OEt)s
The silicone rubber layer used in the present invention may further contain a small amount of photosensitizer.

The silicone rubber layer used in the present invention is prepared by dissolving silicone rubber in a suitable solvent, applying it onto the photosensitive layer, and drying it.

The support of the present invention is preferably one that is flexible enough to be set in a normal lithographic printing machine and that can withstand the load applied during printing, such as metal plates such as aluminum, zinc, copper, and steel, and metal plates such as chromium, zinc, Examples include metal plates plated or vapor-deposited with copper, nickel, aluminum, iron, etc., paper, plastic films, glass plates, resin-coated paper, paper covered with metal foil such as aluminum, and the like.

Among these, aluminum plates are preferred.

The treatment for the support itself to improve the adhesion is not particularly limited, and includes various surface roughening treatments.

The support may have a primer layer, and the primer layer may include, for example, polyester resin, vinyl chloride-vinyl acetate copolymer, acrylic resin, vinyl chloride resin, polyamide resin, polyvinyl butyral resin, epoxy resin, acrylate. Examples include polyvinyl acetate copolymers, vinyl acetate copolymers, phenoxy resins, polyurethane resins, polycarbonate resins, polyacrylonitrile butadiene, and polyvinyl acetate. A compound that generates an acid upon exposure to light and a dye that changes color or fades due to the acid can be added to these brimer layers.

In addition, as the anchor agent constituting the above-mentioned brimer layer,
For example, the aforementioned silane coupling agents, silicone primers, etc. can be used, and organic titanates and the like are also effective.

The thickness of each layer constituting the plate material of the present invention is as follows. That is, the support has a thickness of 50 to 400 μm, preferably 100 μm.
-300 μm, photosensitive layer 0.05-10 μm, preferably 0.5-5 μm, silicone rubber layer 0.1-10 μm
lOμ11 is preferably 0.5 to 2 μm.

In the present invention, a protective layer may be provided on the upper surface of the silicone rubber layer, if necessary.

[Examples] The present invention will be described below with reference to Examples, but the present invention is not limited thereto.

Example 1 [Production of aluminum plate a] An aluminum plate with a thickness of 0.2 mm is immersed in a 3% aqueous sodium hydroxide solution to degrease it, washed with water, and then diluted with hydrochloric acid at a concentration of 1%.
In an aqueous solution with a boric acid concentration of 1%, electrolytic etching was performed at a temperature of 25°C for 5 minutes at a rate of 3A/dm2, and after washing with water, etching was performed in an aqueous solution of 40% sulfuric acid at a temperature of 1.5°C at a temperature of 30°C.
Anodize for 2 minutes at A/dm2, wash with water,
% sodium metasilicate aqueous solution at a temperature of 85°C for 37 seconds, and further immersed in water (pH 8.5) at a temperature of 90°C for 25 seconds, washed with water, and dried to obtain an aluminum plate a.

A photosensitive composition having the composition shown below was applied to an aluminum plate a, and dried at 100° C. for 2 minutes to form a photosensitive layer having a thickness of 0.5 μm.

[Photosensitive composition]

(1) Diazo resin - 150 parts (2) 2-hydroxyethyl methacrylate, N-(4
-Hydroxyphenyl)methacrylamide, acrylic acid copolymer with a molar ratio of 40158/2
50 parts (3) Victoria Pure Blue BOH (dye manufactured by Hodogaya Chemical Co., Ltd.) 1 part (4) Methyl cellosolve 900 parts Synthesis of diazo resin-1 Diazo resin-1 was synthesized as follows. .

14.5 g (50 mmol) of p-diazodiphenylamine sulfate was dissolved in 40.9 g of concentrated sulfuric acid under water cooling. To this reaction solution, 1.35 (45 mmol) of paraformaldehyde was slowly added so as not to exceed the reaction temperature of 10°C.

This reaction mixture was added dropwise to 500 ml of ethanol under water cooling, and the resulting precipitate was filtered. After washing with ethanol, this precipitate was dissolved in 100 ml of pure water, and 6.8
A cold concentrated aqueous solution of 1 g of zinc chloride was added. After filtering the resulting precipitate, it was washed with ethanol, and then washed with 150
Dissolved in ml pure water. To this liquid was added a cold concentrated aqueous solution in which 8 g of ammonium hexafluorophosphate was dissolved. The resulting precipitate was collected by filtration, washed with water, and dried to form a diazo resin.
I got 1.

Next, the following silicone rubber composition was applied onto the photosensitive layer at a dry weight of 2.0 g/m2.
It was dried at ℃ for 10 minutes to obtain a lithographic printing plate material that did not require dampening water.

[Silicone rubber layer composition] Dimethylpolysiloxane having hydroxyl groups at both ends (molecular weight 52,000) 100 parts Triacetoxymethylsilane 10 parts Dibutyltin laurate 0.8 parts Isopar G (manufactured by Esso Chemical) 900 parts of the above plate material After a positive film was vacuum-adhered to the top surface, exposure was performed using a metal halide lamp as a light source. Next, by immersing the plate in warm water at 45°C as a developer and rubbing the plate surface with a sponge, the silicone rubber layer in the unexposed areas is removed, resulting in a printing plate with well-reproduced halftone dots ranging from 2% to 99%. Obtained. Further, no scratches were observed on the silicone rubber layer of the printing plate.

[Comparative Example 1] A test was conducted in the same manner as in Example 1, except that the following developer was used instead of the 45° C. water developer used in Example 1.

[Developer] (p++ 10.8) Pencil alcohol 8 parts by weight Perex NBL (manufactured by Kao Corporation, anionic surfactant) 10 parts by weight Carbonate sorter (Na, Co3) 2 parts by weight Water
80 parts by weight As a result, the halftone dot reproducibility was 3% to 96%, and the reproducibility in shadow areas was particularly poor.

A few scratches on the silicone rubber layer were observed.

Comparative Example 1 A test was carried out in the same manner as in Example 1, except that the photosensitive layer of the waterless planographic plate used in Example 1 was replaced with the water-soluble photosensitive layer shown below.

As a photosensitive layer, a water-soluble photosensitive liquid having the following composition was applied and dried at 100°C for 2 minutes. Dry application weight is 2
, 0g/rn2.

[Water-soluble photosensitive liquid copentaerythritol triacrylate 0.7g poly(allyl methacrylate/potassium methacrylate: copolymerization molar ratio 80/20) (molecular weight 40000) 1.5g Nisrex W-201 (manufactured by Sekisui Blastex) Water-soluble polyvinyl acetal resin) (25% aqueous solution) (molecular weight 40,000) 2.0 g Water 5 g Methanol 15 g As a result, the silicone rubber layer and photosensitive layer in the unexposed area were removed, but the halftone dot reproducibility was 2%. It was 96%, indicating that the reproducibility of the shadow area was poor.

[Effect of the invention] The present invention contains 90% by weight or more of water and pi(5% by weight).
By rubbing the plate surface with a developing solution in the range of .5 to 9.0, the silicone rubber layer in the image area is removed, and as a result, the silicone rubber layer in the non-image area is not scratched and the highlight area is removed. Excellent reproducibility up to part of the shadow. Furthermore, since water is essentially used, it is favorable from the viewpoint of safety and hygiene, and furthermore, it has excellent effects such as no change in developability.

Claims (1)

[Claims] In a method for developing a waterless lithographic printing plate precursor having a photocurable water-insoluble photosensitive layer and a silicone rubber layer on a support in sequence, the plate precursor contains 90% by weight or more of water and has a pH of 5.
A waterless lithographic printing plate precursor, characterized in that the surface of the exposed original plate of the waterless lithographic printing plate precursor is rubbed using a developer in the range of 5 to 9.0 to remove the silicone rubber layer in the image area. Development processing method.