JPH02301760A - Plate making method for damping waterless planographic printing plate - Google Patents

Abstract

PURPOSE:To obtain the damping waterless planographic printing plate having a good developed visible image property by processing the photosensitive planographic printing plate with a soln. contg. a coupler under an alkaline condition during or after development and bringing the same into coupling reaction with a diazo resin on a substrate. CONSTITUTION:A photosensitive layer contg. at least a diazo resin and a silicone rubber layer are applied, in this order from the substrate side, on the substrate having the surface subjected to an anion impartation treatment. The photosensitive planographic printing plate is processed with the liquid contg. the coupler under the alkaline condition during or after the development and is thereby brought into the coupling reaction with the diazo resin on the substrate. The paired anion of this diazo resin forms a stable salt with the diazo resin and includes the anion which makes the resin soluble in an org. solvent. The good developed image property of the positive image is obtd. in this way.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to a method for making a photosensitive lithographic printing plate that does not require a dampening solution, and more specifically, a method for making a photosensitive lithographic printing plate that does not require a dampening solution and provides good developed visible image properties. This invention relates to a method for making a photosensitive lithographic printing plate.

[Prior art] Conventionally, in lithographic printing, it was necessary to perform printing by making use of the lipophilicity of the image area and the hydrophilicity of the non-image area, and by maintaining a delicate balance between water and ink, which required considerable skill. Needed.

In other words, in the conventional printing method that requires dampening water, an image-like lipophilic portion is formed by passing an image film through a plate material coated with a lipophilic photosensitive layer on a hydrophilic support, and then developing it. A printing plate is prepared by providing a hydrophilic area which is a non-image area. During printing, water is first transferred to the non-image areas, and then ink is transferred. The ink does not adhere to the non-print areas where water is present, but only to the print areas. However, with this method, it is difficult to control the delicate balance between dampening water and ink. If you strain the emulsification or mix the ink with the dampening water, it will cause poor ink density and background stains.
This had major problems, such as being a major cause of wasted paper.

Furthermore, the transfer of dampening water to the printing material causes a change in the dimensions of the printing material, which also has the disadvantage that the sharpness of the image is impaired, especially when printing in multiple colors.

For this reason, attempts have been made to develop planographic printing plates that do not require dampening water (hereinafter referred to as "waterless planographic plates"). A waterless lithographic plate is disclosed in which a silicone rubber layer is provided on the upper photosensitive layer, and when the photosensitive layer is dissolved in a developer, the upper silicone rubber layer is removed to form an image area. A plate-making method is described in Japanese Patent Publications No. 54-26923@ and No. 56-23150, which are similar to the above in that a silicone rubber layer is provided on a photosensitive layer on a support. , a method is disclosed in which the photosensitive layer is not dissolved in a developer and the photosensitive layer and silicone rubber layer come into contact with light or undergo photoexfoliation by image exposure, and only the silicone rubber layer is selectively swelled and removed.

Furthermore, JP-A-49-68803 and JP-A-55-12
No. 4148 discloses a photosensitive lithographic printing plate coated with a mixture of a photosensitive material and silicone that does not require dampening water.

[Problems to be Solved by the Invention] Generally, in planographic printing, plate inspection is performed to check tone reproducibility, fog, etc. after plate making and before printing. Such plate inspection is usually performed using the obtained original image.

However, the above-mentioned photosensitive lithographic printing plates that do not require dampening water, especially those disclosed in Japanese Patent Publication No. 44-23042, have insufficient visible image development properties.

Therefore, an object of the present invention is to provide a method for making a lithographic printing plate that does not require dampening water and can obtain good developed visible image properties of a normal image.

[Means for Solving the Problems] In view of the above-mentioned problems, the present inventors have conducted extensive research and found that the above-mentioned object of the present invention is to provide a substrate containing at least a diazo resin on a substrate whose surface has been anionized. A photosensitive lithographic printing plate coated with a photosensitive layer and a silicone rubber layer in this order from the substrate side is treated with a solution containing a coupler under alkaline conditions during or after development to cause a coupling reaction with the diazo resin on the substrate. The inventors have discovered that the present invention can be achieved by providing a process for making a lithographic printing plate that does not require dampening water and is characterized by the following characteristics:

The present invention will be explained in more detail below.

The photosensitive layer used in the present invention contains a diazo resin as an essential component.

As the diazo resin, for example, Photographic Science and Engineering (Pboto
, Sci, Eno, ) Volume 17, Page 33 (19
73), U.S. Patent No. 2,063,631, U.S. Patent No. 2,
Diazo compounds and active carbonyl compounds (e.g. formaldehyde, acetaldehyde, benzaldehyde, etc.) whose production methods are described in the specifications of No. 679.498, No. 3.050.502, JP-A-59-78340, etc. Diazo resin obtained by condensation of
A diazo resin obtained by subjecting a diazo compound and a diphenyl ether derivative to a condensation reaction, the manufacturing method of which is described in Japanese Patent No. 4001, can be used.

The counter anion of the diazo resin used in the present invention is
It contains an anion that forms a stable salt with the diazo resin and makes the resin soluble in organic solvents.

These include organic carboxylic acids such as decanoic acid and benzoic acid;
Contains organic phosphoric acids such as phenyl phosphoric acid and sulfonic acids,
Typical examples include methanesulfonic acid, chloroethanesulfonic acid, dodecanesulfonic acid, benzenesulfonic acid, 1-toluenesulfonic acid, mesidinonesulfonic acid and anthraquinonesulfonic acid, 2-hydroxy-4-
Aliphatic and aromatic sulfonic acids such as me-1-xybenzophenone-5-sulfonic acid, hydroquinonesulfonic acid, 4-acetylbenzenesulfonic acid, dimethyl-5-sulfoisophthalate, 2.2', 4.4'-tetra Hydroxybenzophenone, 1,2. : Hydroxyl group-containing aromatic compounds such as 3-1-lihydroxybenzophenone, 2.2', 4-trihydroxybenzophenone, halogenated Lewis acids such as hexafluorophosphoric acid and tetrafluoroboric acid, C/ ! , O-+, 10. Examples include perhalogen acids such as +, but are not limited thereto. The weight average molecular weight measured with β-naphthol by Gel Permeation Chroma 1 to Graphei method (GPC) is preferably in the range of 200 to 10,000 (in terms of styrene), and more preferably in the range of 500 to 5,000. preferable.

In the present invention, the proportion of the diazo resin in the photosensitive layer is preferably 3 to 60% by weight, more preferably 5 to 50% by weight.

Further, the photosensitive layer according to the present invention can contain a hydroxyl group-containing polymer. As such a hydroxyl group-containing polymer, an alcoholic hydroxyl group-containing poly(meth)acrylic acid ester or amide is preferably used.

Examples of monomers having alcoholic hydroxyl groups include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, N-(4-hydroxyethylphenyl)methacrylamide, and hydroxymethyldiazel.
-(meth)acrylamide, etc.

Monomers copolymerizable with the above hydroxyl group-containing monomers include (1) monomers having an aromatic hydroxyl group, such as N-(4
-Hydroxyphenyl)acrylamide, N-(4-hydroxyphenyl)methacrylamide, 0-1m-1p
-Hydroxystyrene, 0-1m-1p-hydroxyphenyl-acrylate or -methacrylate, (2) α, β-unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic anhydride, (3) Methyl acrylate, acrylic acid Ethyl, propyl acrylate, butyl acrylate, amyl acrylate, hexyl acrylate, octyl acrylate, acrylic acid-
(@-converted) alkyl acrylates such as 2-chloroethyl, 2-hydroxyethyl acrylate, glycidyl acrylate-1-1N-dimethylaminoethyl acrylate-1, (I!I) methyl methacrylate-1, ethyl methacrylate -1~, propyl methacrylate, butyl methacrylate, amyl methacrylate-1~, cyclohexyl methacrylate, 2-hydroxyethyl methacrylate, 4-hydroxybutyl methacrylate-1, glycidyl methacrylate, N-dimethylaminoethyl methacrylate-1 (Substituted) alkyl methacrylates such as (5) acrylamide, methacrylamide, N-methylolacrylamide, N-methylolmethacrylamide, N-ethylacrylamide, N-hexylmethacrylamide, N-cyclohexylacrylamide, N-hydroxyethylacrylamide, Acrylamides or methacrylamides such as N-phenylacrylamide, N-21-phenyl acrylamide, N-ethyl-N-phenylacrylamide, (6) ethyl vinyl ether, 2-chloroethyl vinyl ether, hydroxyethyl vinyl ether, propyl vinyl ether, butyl Vinyl ethers such as vinyl ether, octyl vinyl ether, phenyl vinyl ether, (7) vinyl acetate-1~, vinyl chloroacetate,
Vinyl esters such as vinyl butyrate and vinyl benzoate; (8) Styrenes such as styrene, α-methylstyrene, methylstyrene, and chloromethylstyrene; (9) Methyl vinyl ketone, ethyl vinyl ether, propyl vinyl ketone, and phenyl vinyl ketone. (10) Olefins such as ethylene, propylene, isobutylene, butadiene, isoprene, (11) N-vinylpyrrolidone, N-vinylcarbazole, 4-vinylpyridine, acrylonitrile, methacrylateril, etc. can be mentioned.

The amount of the hydroxyl group-containing monomer in the hydroxyl group-containing polymer is not particularly limited, but is preferably 5% to 95% by weight, particularly preferably 10% to 90% by weight.

The weight average molecular weight of the water M group-containing polymer of the present invention measured by GPC is preferably 5,000 to 1,000,000 (in terms of styrene). If the value is lower than 5000, it may be damaged by the coating solvent or developer of the photosensitive layer even after exposure.
If the value is larger than 1,000,000, it is difficult to select a coating solvent.

The proportion of the hydroxyl group-containing polymer in the photosensitive layer is 5 to 5.
It is preferably 95% by weight, more preferably 10 to 90% by weight.

The weight ratio of diazo resin and hydroxyl group-containing polymer is 1/9
The range of 9 to 90/10 is preferable.

Further, the photosensitive layer of the present invention may also contain a photoinsolubilizable photosensitive substance such as a compound having an addition polymerizable vinyl group.

Compounds having an addition-polymerizable vinyl group include compounds having a polymerizable terminal ethylene group with a boiling point of 100° C. or higher and 2 vJA or higher under normal pressure, such as unsaturated carboxylic acids,
Esters of unsaturated carboxylic acids and aliphatic polyhydroxy compounds, esters of unsaturated carboxylic acids and aromatic polyhydroxy compounds, unsaturated carboxylic acids and polycarboxylic acids, and the aforementioned aliphatic polyhydroxy compounds, aromatic polyhydroxy Examples include esters obtained by an esterification reaction with a polyhydric hydroxy compound, and are specifically described in JP-A-59-71048 and the like.

In addition to the above-mentioned materials, the photosensitive layer of the present invention may also contain dyes, pigments, or exposure-visible agents, if necessary.
By adding a coating property improver or the like, it is possible to improve the developed visible image properties, the exposed visible image properties, and the coating properties.

Examples of the above-mentioned dyes include Bikku 1 to Rear Pico Blue BOH, Oil Blue #603, and Oil Pink #312.
, Pachinmil Pure Blue, Crystal Violet,
Leuco Crystal Violet 1~, Brilliant Green, Ethyl Violet, Methyl Green, Erythrosin B, Pesic Tsuksin, Malachite Green, Leuco Malachi 1~ Green, m-Cresol Purple, Cresol Red, Xylenol Blue, Rhodamine B1
1-diphenylmethane type typified by auramine, 4-p-diethylaminophenylimino naphthoquinone, cyano-1)-diethylaminophenylacetanilide, etc.
diphenylmethane series, ochrydine series, xanthene series,
Examples include imino nano-1 to quinone-based, azomethine-based, or anthraquinone-based dyes.

The above dyes are generally present in the photosensitive layer in an amount of 0.01 to about 10% by weight.
, preferably about 0.05% to 8.0%.

Examples of coating properties improvers include alkyl ethers (e.g., ethyl cellulose, methyl cellulose), fluorine-based surfactants, and nonionic surfactants (e.g., Pluronic L-f) (manufactured by Kadenka Co., Ltd.)) FC-430 ( sumitomo 3
(manufactured by M), etc.

Further, examples of the exposure-visible image agent include 1 to riazine compounds, oxadiazole compounds, and the like.

In the present invention, the thickness of the photosensitive layer is 0. In+g/ (1
712-30m (1/dv' is preferable, 0.5mO/
di' to 10Ia+1/dt' is more preferred.

In the present invention, a silicone rubber layer is further provided on the photosensitive layer, and the silicone rubber used in the silicone rubber layer is preferably linear or crosslinked organopolysiloxane. The organopolysiloxane usually has a molecular weight of 10 to 100 yen, and is suitably crosslinked in the form of a liquid, wax, or cake at room temperature. The organopolysiloxanes are classified into integrated type and addition type depending on the crosslinking method.

U2 The integrated type is one in which crosslinking is performed by an integrated reaction, and water, alcohol, organic acids, etc. are released by the reaction. Particularly useful integrated silicone rubbers include those prepared by reacting a silicone crosslinking agent with a linear organopolysiloxane having hydroxyl groups at both ends or a part of the main chain, and reacting the hydroxyl groups with the silicone crosslinking agent. In either case, adding a condensation catalyst is advantageous in terms of crosslinking speed.

The organopolysiloxane has the following repeating units in its main chain.

→S: -O← In the formula, R1 and R2 are alkyl, aryl, alkenyl, or a combination thereof, each of which may have a substituent such as a cyano group, a halogen atom, or a hydroxyl group, and a methyl group or a phenyl group. , a vinyl group, and a trifluoropropyl group are preferable, and a megul group is also particularly preferable.

The above-mentioned silicone crosslinking agents include so-called acetic acid-removal type, oxime-removal type, alcohol-removal type, deamine-removal type, which have a functional group represented by -〇H (in the formula, R and R' are alkyl groups); Examples include condensation type silicone crosslinking agents such as dehydrated type. Examples of such crosslinkers include tetraacetoxysilane, methyltriacetoxysilane, ethyltriazetoxysilane, phenyltriacetoxysilane, dimethyldiacetoxysilane, diethyldiacetoxysilane, vinyltriacetoxysilane, methyltrimethoxysilane, Silane, dimethyldimethoxysilane, vinyltrimethoxysilane, methyltris(
acetone oxime) silane, methyltri(N-methyl,
Examples include N-acetylamino)silane, vinyl l-su(methylethylketoxime)silane, methyltri(methylethylketoxime)silane, and oligomers thereof.

All of these crosslinking agents are organopolysiloxane 10
It is preferable that the amount is in the range of 05 to 30 parts by weight relative to 0 parts by weight.

Examples of the condensation catalyst include organic carboxylic acids, titanate esters, naphthenic acids, and the like.

The addition type refers to an unsaturated group in the main body, such as a vinyl group (-C
It refers to something that is crosslinked by adding a hydroxyl group in a crosslinking agent to H=CH2).

Specifically, platinum-based catalysts such as vinyl group-containing A luganoborisiloxane, hydrogenated organopolysiloxane, etc., such as platinum chloride! ! One example is a mixture of i), etc.

The organopolysiloxane has repeating units similar to those of the condensed type in the main chain.

In the silicone rubber layer of the present invention, either or both of a condensation type silicone rubber and an addition type silicone rubber can be used.

It is also possible to use condensed and addition type organopolysiloxanes having hydroxyl groups, unsaturated groups, etc. in one organopolysiloxane.

Among the commercial products available as the silicone rubber according to the present invention, preferred examples include KS-705F manufactured by Shin-Etsu,
KE-41, 42, 44, Toshiba Silicone (manufactured) Y
E 5505. Y F 3057, Toshi Silicone (manufactured by) SH-781, PRX-305, 5t-1-2,37
Condensation type silicone rubber such as KS-837 manufactured by Shin-Etsu,
, KE-103, KE-106, KE-1300, Toshiba Silicone (pIA) TSE-3032, RTU-B,
Examples include additive silicone rubber such as SH-9555 manufactured by Toshi Silicone Co., Ltd.

Furthermore, for the purpose of improving the strength of silicone rubber, inorganic fillers such as silica, titanium oxide, and aluminum oxide may be added, and silica is particularly preferably used.

From the viewpoint of dispersibility or dispersion stability, such fillers preferably have an average particle diameter of 500 μm or less.

In the present invention, the thickness of the silicone rubber layer is preferably as thin as possible from the point of view of image quality and developability, but on the other hand, a certain thickness is required from the point of view of printing durability, printing stains, etc., so generally 3 mu /di2 to 50 mg/dm' is preferable, and 5 mg/di' to 30 m(1/(In'
is more preferable.

In the present invention, an adhesive layer made of epoxy resin or the like may be provided between the photosensitive layer and the silicone layer, and the adhesive layer may contain various reactive crosslinking agents, silane coupling agents, etc. The thickness of the adhesive layer is 0. img/
d12-5 mo/dn' is preferred.

Furthermore, in the present invention, a protective layer may be provided on the silicone rubber layer in the waterless lithographic plate, and a method for providing the protective layer is to laminate a polypropylene film or the like described in Japanese Patent Publication No. 61-614. Method and Japanese Unexamined Patent Publication No. 61-27547
The method of applying the high molecular weight polymer described in No. 1 is known.

The substrate used in the present invention is an anionized substrate.

As such a substrate, an aluminum plate or an aluminum foil is preferable, and an aluminum plate is particularly preferable from the viewpoint of printing durability.

In the present invention, the surface of the aluminum plate or aluminum foil is grained and anodized if necessary.
After c, anionization treatment is performed. At that time, the anionization process is
For example, it is carried out by immersion in an aqueous solution of an anionizing treatment agent such as sodium silicate, sodium phosphate, phosphoric acid, etc. with a concentration of 0.1 to 10% at a temperature of 30 to 95 ° C. for 1 second to 2 minutes.
Preferably, it is then treated by immersing it in water at a temperature of 40 to 95°C for 10 seconds to 2 minutes. Through such anionization treatment,
Adhesion between the diazo resin in the photosensitive layer and the substrate is improved.

In the present invention, after the photosensitive lithographic printing plate prepared as described above is imagewise exposed, it is developed with a developer using a conventional method to dissolve the photosensitive layer in the unexposed area and removed together with the silicone rubber layer thereon. By doing so, the board is exposed as an image area,
A waterless lithography is formed. At this time, a small amount of diazo resin remains on the substrate in the image area.

Therefore, in the present invention, the substrate is treated with a solution containing a coupler under alkaline conditions to cause a coupling reaction between the coupler and the remaining diazo resin on the substrate, and the image area is dyed to obtain a visible image. The coupling reaction between the coupler and the remaining diazo resin may be carried out during or after development.

The above-mentioned couplers include (a) phenols or nano-ols having a phenolic hydroxyl group, (b) aromatic amines, (C) aliphatic compounds having an enolizable keto group such as acetoacetanilide, (d) Heterocyclic compounds such as 5-pyrazolone and pyrrole are used,
Preferably, (a) phenols or naphthols having a phenolic hydroxyl group or (b) aromatic amines are used. Such couplers are dissolved in a solvent such as water, ethanol, dioxane, acetone, etc.
Preferably, it is used as a 20% solution.

The coupling reaction of the above coupler with the diazo resin is carried out under alkaline conditions, preferably at a pH value of 7 to 7.
The test was carried out under 13 conditions.

The treatment with the coupler-containing solution is usually carried out by immersing the plate in the coupler-containing solution, by pouring the coupler-containing solution onto the plate surface, or by rubbing it with a cloth, brush, etc. containing the coupler-containing solution.

As the light source used for exposure, any general-purpose light source including ultraviolet rays of 180 nm or more and visible light may be used, but carbon arc lamps, mercury lamps, xenon lamps, metal halide lamps, strobes, etc. are particularly preferred.

The developer used in the development process includes water, the following polar solvents, alkaline compounds such as amines, surfactants, and, if necessary, aliphatic hydrocarbons (hexane, heptane, etc.).
``Isopar E1, G'' (trade name of aliphatic hydrocarbons manufactured by Esso Chemical) or gasoline, kerosene, etc.), aromatic hydrocarbons (toluene, xylene, etc.), or halogenated hydrocarbons (triclene, etc.). Those added are suitable.

Polar solvent alcohols (methanol, ethanol, water, etc.) Ethers (methyl cellosolve, ethyl cellosolve, butyl cellosolve, methyl carpitol, ethyl carpitol xane, etc.) Ketones (acetone, methyl ethyl ketone, etc.) Esters (ethyl acetate, methyl cellosolve acetate) , cellosolve acetate, carpitol acetate, etc.) Development can be carried out by various known methods, such as rubbing with a developing pad containing a developer as described above, or rubbing with a developing brush after pouring a developer onto the printing plate. be able to.

[Example] The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited to the Examples.

(Synthesis of Diazo Resin-1) 145 g of p-diazodiphenylamine sulfate was dissolved in 409 g of concentrated sulfuric acid under water cooling. To this reaction solution, 10 g of rose formaldehyde was slowly added dropwise so that the reaction temperature did not exceed 10°C. Thereafter, stirring was continued under water cooling for 2 hours. The reaction mixture was added dropwise to 500 vQ of ethanol under ice cooling, and the resulting precipitate was filtered. After washing with ethanol, the precipitate was washed with 100 ml of pure water. A cold concentrated aqueous solution containing 6.8 g of zinc chloride was added to this solution.The resulting precipitate was filtered, washed with ethanol, and dissolved in 150 d of pure water.To this solution, A cold concentrated aqueous solution in which 8 g of ammonium hexafluorophosphate was dissolved was added.The resulting precipitate was collected by filtration, washed with water, and then dried at 30°C overnight to obtain diazo resin-1.

The weight average molecule m (MW) in terms of styrene measured by GPC method of the coupled product with β-naphthol is 150
0, and the number average molecular weight was 500.

(Synthesis of Polymer 1) N-(4-hydroxyphenyl) methacrylamide 49
．． 6Q, acrylonitrile 36. IQ, methyl methacrylate 172Q was dissolved in distilled acetone 190 or distilled methanol 190112 (1--tal monomer concentration: 5.3 mol/i), azobisisobutyronitrile 12
The polymerization reaction was carried out under reflux in a nitrogen stream for 8 hours (37 mol % by adding +). After the reaction was completed, the mixture was poured into water and separated to obtain 168 g of a white resin (Polymer 1).

Measured values by GPC method are not shown below.

MW: 2.4X 10'1. Dispersion ratio = 2.1 Example-1 A degreased and washed aluminum plate was placed in a 3% by weight aqueous hydrochloric acid solution.
Graining was carried out by electrolytic etching for 5 minutes at 25°C and a current density of 3 A/du', and then 09 weight (5)%
After treating Despine 1 with an aqueous sodium hydroxide solution and washing with water, it was treated with a 10% by weight sulfuric acid aqueous solution at 30°C, 1.5
Anodic oxidation treatment was performed for 2 minutes under the conditions of A/di' and washed with water. Further, the substrate was treated with sodium silicate using a 1% by weight aqueous sodium silicate solution at 85° C. for 25 seconds, and then washed with water to obtain Substrate-1.

The following photosensitive composition was coated on the obtained substrate-1 at 55°C using a whirler, and dried at 85°C for 3 minutes to provide a photosensitive layer. The dry film thickness was 31H/di'.

Photosensitive composition Polymer - 1100 parts Diazo resin - 120 parts Methyl cellosolve 1000 parts Ethyl cellosolve 1000 parts The following silicone rubber composition was placed on the above photosensitive layer at a dry weight of 20 mo
/di2 at 55°C and dried to form a silicone rubber layer.

Silicone rubber layer made of silicone S H-237 100 parts Methyl tris (methyl ethyl ketoxime) silane 4 parts Dibutyltin diacetate 1 part A positive film was placed on the obtained printing original plate and heated at 100 mJ with a 3 KW ultra-high pressure mercury lamp.
/ (After 12 exposures, it was immersed in the following developer for 1 minute and rubbed with a development bat to remove the photosensitive layer and silicone rubber in the unexposed areas.

1 image 1 phenyl cellosolve 10 parts Jetanolamine 4 parts Pionin A-44B (manufactured by Takemoto Yushi) 6 parts water
When 80 copies of this plate were immersed in the following stain solution 1, a positive colored image was obtained.

Staining solution-1 β-naphthol 5 parts Na O
H5 part 9 part example-
2 The plate prepared in Example-1 was immersed in the following staining solutions -2 and -3 containing the couplers shown below, respectively, to obtain positive colored images.

Dyeing liquid-2 and -3 coupler 5 parts 1 cut a○
1" 5 parts water
90 parts Cumbler (both manufactured by Ohtsuka Kagaku Co., Ltd.) Example-3 The same procedure was carried out except that a board obtained by further immersing the substrate used in Example-1 in a 40% Ha PO4 aqueous solution at 50°C for 30 seconds was used. A plate was prepared in the same manner as in Example 1, and when dyed in the same manner, a positive image with high color density was obtained.

Example-4 The developed plate obtained in Example-1 was dyed with the following stain solution 4 or 5.
When immersed in water, positive images with high color density were obtained in all cases.

Staining solution-4,5 Coupler 5 parts NaO
H5 part water
90 parts 5-pyrazolone (staining solution-5) [Effects of the invention] As explained in detail above, by the plate-making method of the present invention,
A lithographic printing plate that does not require dampening water and has good developing and visible image properties can be obtained.

Patent applicant Mitsubishi Kasei Corporation (1 other person)? 8

Claims (1)

[Claims] A photosensitive lithographic printing plate, in which a photosensitive layer containing at least a diazo resin and a silicone rubber layer are coated in this order from the substrate side on a substrate whose surface has been anionized, is coated with a coupler under alkaline conditions during or after development. A method for making a lithographic printing plate that does not require dampening water, characterized in that it is treated with a solution containing a solution to cause a coupling reaction with a diazo resin on a substrate.