JPH02216152A - Damping-waterless photosensitive planographic printing plate - Google Patents

Abstract

PURPOSE:To improve the ink repulsiveness, physical strength and adhesiveness of the printing plate by providing a photosensitive layer essentially consisting of silicone rubber, diazo resin and inorg. filler on a substrate subjected to a treatment for anion formation. CONSTITUTION:This printing plate is formed by providing the photosensitive layer essentially consisting of the silicone rubber (B), the diazo resin (C) and the inorg. filler (D) on the substrate (A) subjected to the treatment for anion formation on the surface. The substrate formed by degreasing an Al sheet, sand graining the sheet by an electrolytic etching method, etc., and anodizing the sheet, then subjecting the sheet to the treatment for anion formation with alkali metal silicate, etc., is usable for the substrate A. A mixture composed of polyorganosiloxane having hydroxyl groups at both terminals, etc., and silicone crosslinking agent or the like is usable for the component B, the desired diazo resin is usable for the component C and silica, etc., are usable for the component D.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a lithographic printing plate material that does not require dampening water. More specifically, the present invention relates to a lithographic printing material that does not require dampening water and has excellent ink repellency, physical strength, and adhesiveness.

(Prior art) Conventionally, with lithographic printing materials, it has been necessary to print with a delicate balance of water and ink by utilizing the lipophilicity of the image area and the hydrophilicity of the non-image area, which requires considerable skill. Therefore, there has been a strong desire for a lithographic printing plate material that does not use printing precipitation and does not require dampening water.

In other words, in the conventional printing method that requires dampening water, an image-like photosensitive layer is formed by exposing and developing an image film through a printing plate (PS plate) in which an oleophilic photosensitive layer is coated on a hydrophilic support. A printing plate is prepared by providing an oily part and a hydrophilic part. During printing, water is first transferred to the non-image area, and then ink is transferred. Ink does not adhere to non-print areas where water is present,
Only the image area is attached. However, with this method, it is difficult to control the delicate balance between dampening water and ink, causing emulsification of the ink, and ink mixing with the dampening water, resulting in poor ink concentration and scumming, which is a major cause of paper waste. It was a problem with the platform.

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

For this reason, attempts have been made to develop a lithographic printing plate that does not require dampening water, but none of the plates known to date have sufficiently satisfactory properties for widespread practical use.

For example, Tokuko Sho 42-23042, Tokusho 46-1604
4, Special Publication No. 54-26923, Special Publication No. 56-23150
, JP 55-47383, JP 61-613, JP 48-33910, JP 50-903, JP 49
This method is described in Publication No. 68803 and the like.

(Problems to be solved by the invention) However,
44, Special Publication No. 54-26923, Special Publication No. 56-2315
The method described in No. 0, etc. has a structure in which a silicone layer is provided over the photosensitive material layer on the support, so the developer must pass through a uniform silicone layer to reach the photosensitive layer. Therefore, the silicone layer must be made thinner.
Therefore, it was not possible to obtain sufficient ink repellency, and it was easily damaged, and the adhesiveness between the photosensitive layer and the silicone layer was insufficient, and sufficient stiffness resistance could not be obtained.

On the other hand, the methods described in Japanese Patent Publication No. 55-47383 and Japanese Patent Publication No. 61613 have a structure in which a photosensitive layer is provided on a silicone layer on a support, and some of the above-mentioned drawbacks can be improved. However, it is necessary to laminate a photosensitive layer that has low affinity with the silicone layer. Therefore, it is difficult to form a photosensitive layer by coating, so 1. Although it is manufactured by pressure-bonding a silicone layer on a support, such a method is subject to significant manufacturing restrictions.

Furthermore, the methods described in JP-A-48-33910 and JP-A-50-903 have a structure in which photosensitive silicone is coated on a support, which is advantageous in terms of production since it is a single layer, but silicone In order to make photosensitive silicone by modifying it, the ink repellency of the silicone has to be reduced, and therefore it has not always been possible to obtain sufficient ink repulsion.

JP-A-49-68803 and JP-A-55-124148 describe lithographic printing plates that do not require dampening water and are coated with a mixture of a photosensitive substance and silicone on a support, but they are still lacking in strength. It was weak and had poor adhesion, making it impossible to obtain sufficient rigidity.

(Object of the present invention) Therefore, the object of the present invention is to provide a novel presensitized lithographic printing plate that does not require dampening water and eliminates these drawbacks.

(Means for Solving the Problems) In order to achieve the above object, the inventor of the present invention, as a result of intensive studies, has discovered that silicone resin, diazo resin, and inorganic filler are used as main components on a substrate subjected to anionization treatment. Surprisingly, by providing a photosensitive layer, even though it is a single photosensitive layer, it has excellent ink repulsion, physical strength and adhesion, and pre-sensitized planographic printing that does not require dampening water. The present invention was achieved by discovering that a plate can be obtained.

That is, the gist of the present invention is to provide a photosensitive material that does not require dampening water and is characterized in that a photosensitive layer containing silicone rubber, diazo resin, and an inorganic filler as main components is provided on the anionized group (on the reverse side). Exists in lithographic printing plates.

(Specific structure of the invention) The present invention will be explained in detail below.

The substrate used in the present invention is not particularly limited, including its layer structure, as long as it has the flexibility to be set in a normal lithographic printing machine and can withstand the load applied during printing.

Examples include papers such as coated paper, metal plates such as aluminum plates, and plastic films such as polyethylene terephthalate.

As the substrate of the present invention, an aluminum plate or a composite material of aluminum foil and other materials is preferable, and an aluminum plate is particularly preferable from the viewpoint of rigidity.

The substrate of the present invention is one whose surface has been anionized, but prior to this treatment, known graining, anodic oxidation, etc. may be performed.

For example, the method of graining the surface of an aluminum plate is
After the surface has been degreased, it is grained using a brush polishing method, a ball polishing method, a chemical polishing method, or an electrolytic etching method, preferably an electrolytic etching method that produces deep and uniform grains. For example, anodizing treatment is performed using an inorganic salt such as phosphoric acid, chromic acid, boric acid, or sulfuric acid, or an organic acid such as oxalic acid alone, or in an aqueous solution of a mixture of two or more of these acids.
Preferably, this is carried out by passing an electric current through an aluminum plate as an anode in an aqueous sulfuric acid solution. The amount of the anodic oxide coating is preferably 5 to 60 mg/dm2, more preferably 5 to 30 mg/dm''.

The anionization treatment is performed, for example, by immersion in an aqueous solution of an acid or a salt thereof.

Examples of acids or salts thereof used in the present invention include inorganic acids such as silicic acid, phosphonic acid, zirconic acid, and phosphoric acid; percussion acids such as oxalic acid and adipic acid; or alkali metal galates and phosphonic acids. salts, salts of inorganic acids such as zirconates,
Examples include salts of organic acids such as oxalates and adipates. In terms of width, developability, and adhesiveness, inorganic acid salts are preferred, and alkali metal silicates are particularly preferred. In the present invention, the surface treatment of the substrate with the acid or its salt is usually O,j, wt% to 10 wt%, preferably 0.5
The substrate is immersed in an aqueous solution of tvt% to 5wt%, and
i o o 'c, preferably from 50''C to 95°C,
This is carried out by processing for about 1 second to 10 minutes, preferably about 5 seconds to 5 minutes.

Particularly in the present invention, it is particularly preferable that the surface of the aluminum plate or aluminum foil is grained, then anodized, and further treated with silicate. At that time, the silicic acid treatment is performed using, for example, a sodium silicate aqueous solution with a concentration of 0.1.
~10%, by immersion for 1 second to 2 minutes at a temperature of 30 to 95°C, preferably followed by immersion in water at a temperature of 40 to 95°C.
It is processed by immersion for 0 seconds to 2 minutes.

The silicone rubber used as the first component of the photosensitive layer is a linear or somewhat crosslinked polyorganosiloxane. Polyorganosiloxane usually has a molecular weight of 100,000 to several hundred thousand, and is liquid, waxy, or cake-like at room temperature, and is often moderately crosslinked. Depending on the method of crosslinking, polyorganosiloxane can be divided into condensation type and addition type. It will be done.

Clamping molds are those in which crosslinking occurs through a condensation reaction, and water, alcohol, organic acids, etc. are released as a result of the reaction. Particularly useful condensation type silicone rubbers include those in which a mixture of a linear polyorganosiloxane having hydroxyl groups at both ends or a part of the main chain and a silicone crosslinking agent is reacted with the silicone crosslinking agent, and both Adding a condensation catalyst is advantageous in terms of crosslinking speed.

The main chain of polyorganosiloxane has the following repeating units.

US-5i-0± Silicone crosslinking agents are condensation type silicone crosslinking agents, such as the so-called acetic acid-removal type, oxime-removal type, alcohol-removal type, deamination type, dehydration type, etc., which have a functional group represented by an alkyl group. It is. Examples of such crosslinkers include tetraacetoxysilane,
Methyltriacetoxysilane, ethyltriacetoxysilane, phenyltriacetoxysilane, dimethyldiacetoxysilane, diethyldiacetoxysilane, vinyltriacetoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, vinyltrimethoxysilane, methyltris(acetoneoxime)silane , methyltri(
Examples include N-methyl, N-acetylamino)silane, vinyltri(methylethylketoxime)silane, methyltri(methylethylketoxime)silane, and oligomers thereof.

The amount of each of these is preferably in the range of 0.5 to 30 parts by weight per 100 parts by weight of the polyorganosiloxane.

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

The addition type refers to one in which a hydroxyl group in a crosslinking agent is added to an unsaturated group in the main body, such as a vinyl group (-CH=CH2), resulting in crosslinking.

Specifically, it is a mixture of a vinyl group-containing organopolysiloxane, a hydrogenated organopolysiloxane, and a platinum-based catalyst (for example, chloroplatinic acid). The repeating unit of the main chain of polyorganosiloxane is the same as that of the condensed type.

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

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

Some preferred examples of commercially available products include condensation type silicone rubbers such as KS-705F manufactured by Shin-Etsu;
KE-41, 42, 44, Toshiba Silicone (manufactured) YE5
505, Toshi Silicone (manufactured by) SH-781, PRX-
305,5H-237, and addition-type silicone rubbers include Shin-Etsu's KS-837, KE-103,
KE-106, KE-1300, manufactured by Toshiba Silicone
TSE-3032RTU-B, Toshi Silicone (manufactured by) S
Examples include H~9555.

The silicone rubber is contained in the photosensitive layer in an amount of 30 wt% to 98 wt%, preferably 50-L% to 95 wt%.

If it is less than 30-t%, there is a problem with ink repulsion, and 9
If it is more than 8 wt%, the content of photophores will be reduced and image characteristics will be affected.

As the diazo resin used as the second component of the photosensitive layer, conventionally known ones can be used as appropriate, but diazo resins typified by condensates of aromatic diazonium salts and, for example, active carbonyl-containing compounds, especially formaldehyde, are preferred. Among them, diazo resins soluble in organic solvents are preferred.

Preferred specific examples of the diazo resin include resins represented by the following formula (7) and having a molecular weight of about 500 to 10.000.

In the formula, R'', R'' and R14 each represent a hydrogen atom, an alkyl group or an alkoxy group, preferably a hydrogen atom, and RI5 represents a hydrogen atom, an alkyl group or a phenyl group, preferably a hydrogen atom.

X in the formula represents a counter anion of the diazo resin, specifically, organic carboxylic acids such as PFb, BF, decanoic acid, benzoic acid, organic phosphoric acids such as phenylphosphoric acid, and sulfones such as methanesulfonic acid. Indicates acids, etc.

Y in the formula represents NH, S, and O. Furthermore, Z in the formula is a sulfonic acid group, a sulfonate (Na salt, 1, etc.)
group, sulfine group, sulfinate (Na salt, K salt, etc.)
The ratio of m and n is m/m in molar ratio.
n = 1/0 to 10, preferably 110 to 2.

The content of diazo resin in the photosensitive layer is preferably 1 to 70
It is selected from the range of 3% to 60% by weight, more preferably 3% to 60% by weight.

Examples of the inorganic filler used as the third component of the photosensitive layer include silica, titanium oxide, aluminum oxide, etc. alone or in mixtures. These are added for the purpose of improving the strength of silicone rubber, and are 0.1 wt% to 100 wt%, preferably l
Add 50% to 50%.

Among these, silica is preferable from the viewpoint of mechanical strength, and from the viewpoint of dispersibility or dispersion stability, it is preferable that the average diameter of the particles is 500 nm or less, and lnm-1
100n is more preferable. The average particle diameter referred to herein is at least the primary average diameter obtained by measuring the diameters of 3,000 or more particles and taking the arithmetic mean thereof.

In addition to the materials described above, dyes, pigments, coatability improvers, plasticizers, stabilizers, etc. can be added to the photosensitive layer of the present invention, if necessary.

Furthermore, it is also possible to contain a known exposure-visible image imparting agent.

Examples of the above dyes include Victoria Pure Blue BOH, Oil Blue #603, and Oil Pink #312.
, patent pure blue, crystal violet, leuco crystal violet, brilliant green,
Ethyl violet, methyl green, erythrosin B
Representative examples include 1 basic tsuksin, malachite green, leucomalachite green, m-cresol purple, cresol red, xylenol blue, rhodamine B, auramine, 4-p-diethylaminophenylimino naphthoquinone, cyano-p-diethylaminophenyl acetanilide, etc. Examples include triphenylmethane-based, diphenylmethane-based, oxazine-based, xanthine-based, iminonaphthoquinone-based, azomethine-based, and anthraquinone-based dyes.

The dye is generally contained in the photosensitive layer in an amount of about 0.01 to about 10% by weight, preferably about 0.05 to 8% by weight.

Examples of the coating properties improver include alkyl ethers (eg, ethyl cellulose, methyl cellulose), fluorocarbon surfactants, and nonionic surfactants (eg, Pluronik L-64 (manufactured by Asahi Denka)).

Plasticizers for imparting flexibility and abrasion resistance to coating films include, for example, butyl, tylphthalyl, polyethylene glycol, tributyl citrate, diethyl phthalate, dibutyl phthalate, dihexyl phthalate, dioctyl phthalate, and tricresyl phosphate. , tributyl phosphate, trioctyl phosphate, tetrahydrafurfuryl oleate, oligomers of acrylic acid or methacrylic acid, and the like.

Examples of stabilizers include polyacrylic acid, tartaric acid, phosphoric acid, phosphorous acid, organic acids (acrylic acid, methacrylic acid,
citric acid, oxalic acid, benzenesulfonic acid, naphthalenesulfonic acid, 4-methoxy2-hydroxybenzophenone-5-sulfonic acid, etc.).

The amount of these additives added varies depending on the purpose of use, but is generally 0.01% to 30% by weight based on the total solid content.
Weight percent is preferred.

Further, a known exposure-visible image-imparting agent can be contained, and the exposure-visible image-imparting agent is a compound that generates an acid upon exposure to form a salt with a dye.

As a compound that generates an acid upon exposure to light, a trihaloalkyl compound represented by the following format is preferable.

(However, Xa is a trihaloalkyl group having 1 to 3 carbon atoms, W is N or P, and Z' is 0, S or S
e, and Y' is a group that cyclizes W and Z' and has a chromophore. ) Specific compounds include oxadiazole compounds having a benzofuran ring such as υ,
2-Trichloromethyl-5-(p-methoxysdyryl kl, 3
．． Examples include 4-oxadiazole compounds.

Also, 4-(2,4-dimethoxy-4-styryl)-6-1- described in JP-A No. 53-36223
Dichloromethyl-2-pyrone compound tl, 2,4-bis-
(trichloromethyl)-6-pmethoxystyryl-5-
Examples thereof include h-lyazine compound, 2°4-bis-(trichloromethyl)-6-p-dimethylaminostyryl-s-triazine compound, and the like.

The amount of the exposure visible image imparting agent added is 0.01 to 20 in the photosensitive layer.
It is preferably 0.1 to 5% by weight, more preferably 0.1 to 5% by weight.
Weight%.

The photosensitive layer of the present invention is prepared by dissolving or dispersing each of the components described above in a solvent and coating it on an ink-receptive substrate.
Formed by drying.

The film thickness is preferably 0.1 g/m'' to 10 g/m2, particularly preferably 1 g/m2 to 5 g/m''.

The method for producing a photosensitive lithographic printing plate that does not require dampening water according to the present invention will be explained below.

The invention is obtained by applying a photosensitive layer onto an ink receptive substrate. The photosensitive layer is coated using a solvent that dissolves or disperses each of the above-mentioned components, but solvents that can be used include:
Cellsolves such as methyl cellosolve, methyl cellosolve acetate, ethyl cellosolve, ethyl cellosolve acetate, carpitols such as methyl calpitol and ethyl carpitol, dimethyl formamide, dimethyl sulfoxide, dioxane, acetone, methyl ethyl ketone, cyclohexanone, trichloroethylene, Examples include diacetone alcohol, toluene, xylene, hexane, cyclohexane, methanol, ethanol, heptane, Isopar H (manufactured by Esso Chemical Co., Ltd.), and the like. These solvents may be used alone or in combination of two or more. The ink receptive substrate can be coated by conventionally known methods such as spin coating, wire bar coating, dip coating, air knife coating, roll coating, plate coating, and curtain coating. After coating, the coating film is sufficiently dried and preferably subjected to a heat treatment to obtain the dampening water-free photosensitive lithographic printing plate of the present invention.

In order to make the dampening water-free photosensitive lithographic printing plate of the present invention obtained as described above, a conventional conventional method is applied. That is, a relief image is obtained by exposing to light through a transparent original image having a line image, halftone image, etc., and then developing with a developer. A suitable light source for exposure is 180 nm.
Any general-purpose light source including the above ultraviolet rays and visible rays may be used, but in particular carbon arc lamps, mercury lamps,
Xenon lamps, metal halide lamps, strobes, etc. are recommended.

The developer used in the development process of the photosensitive lithographic printing plate that does not require dampening water of the present invention is aliphatic hydrocarbons (hexane, heptane, "isopar E, H, G" (manufactured by Esso Chemical Co., Ltd.). product name) or gasoline, kerosene, etc.)
, aromatic hydrocarbons (toluene, xylene, etc.) or halogenated hydrocarbons (triclene, etc.) to which the following polar solvents are added are suitable.

Alcohols (methanol, ethanol, water, etc.) Ethers (methyl cellosolve, nine del cellosolve, butyl cellosolve, methyl carpitol, ethyl carpitol, butyl carpitol, dioxane, etc.) Ketones (acetone, methyl ethyl ketone, etc.) Esters (ethyl acetate, etc.) , methyl cellosolve acetate, cellosolve acetate-1, carpitol acetate, etc.) It is also possible to dye the image area simultaneously with development by adding a dye such as crystal violet or acetracine red to the developer.

Development can be carried out by a known method, such as rubbing with a developing pad containing a developer as described above, or pouring a developer onto the printing plate and then rubbing with a developing brush.

(Examples) The present invention will be described in more detail below with reference to Examples, but the present invention is not limited to the Examples unless it exceeds the gist thereof.

(Synthesis of Diazo Resin-1) 10 g of p-diazodiphenylamine sulfate and 3 g of sodium benzenesulfonate were dissolved in 4.09 g of concentrated sulfuric acid under water cooling. 1.0 g of rose formaldehyde was slowly added dropwise to this reaction solution. At this time, the addition was carried out so that the reaction temperature did not exceed io'c. Thereafter, stirring was continued for 2 hours under water cooling. This reaction mixture was heated for 500 m under water cooling.
1 of ethanol, and the resulting precipitate was filtered. After washing with ethanol, this precipitate was dissolved in 100 mj2 of pure water, and to this solution was added a cold concentrated aqueous solution in which 6.8 g of zinc chloride was dissolved. The resulting precipitate was filtered, washed with ethanol, and dissolved in 150 rn 1 of pure water.

To this liquid was added a cold concentrated aqueous solution in which 8 g of ammonium -\xafluorophosphate was dissolved. The resulting precipitate was collected by filtration, washed with water, and then dried at 30'C for a day and night to obtain diazo resin 1.

The weight average molecular weight in terms of styrene measured by GPC method is 1
430, and the number average molecular weight was 450.

(Synthesis of Diazo Resin-2) Diazo Resin-2 was obtained in exactly the same manner except that 3 g of p-hydroxybenzoic acid was used instead of 3 g of sodium benzenesulfonate in Diazo Resin-1.

The weight average molecular weight in terms of styrene measured by GPC method is 1
．． 400, and the number average molecular weight was 500.

(Example 1) A degreased and cleaned aluminum plate was desmatched with a 0.9 wt% NaOH aqueous solution by electrolytic etching under the conditions of 3 wt% hydrochloric acid and 25° C13A/dm for 25 minutes, washed with water, and grained to 40 wt%. Sulfuric acid, 30°C
After anodizing at 11,5A/dI for 1122 minutes, washing with water, and treating with sodium silicate at 1 wt% at 85°C for 125 seconds, 1. After washing with water (substrate-1
).

The following photosensitive layer was dispersed in a MEK/acetone solution and then coated on this substrate-1, and dried at 100"C for 12 minutes. Thereafter, it was heated at 55°C for 20 hours to form a layer with a thickness of 3 g/
A photosensitive lithographic printing plate (1) which does not require m2 dampening water was obtained.

(a) 100 parts of dimethylpolysiloxane (Mn=120000) having hydroxyl groups at both ends (b) Methyltri(methylethylketoxime)silane
5 parts (C) Diptyltin diacetate 0.5 parts (d) Diazo resin - 18 parts (e) Aerosil Imer 972 (B, t manufactured by Aerosil ■) 5 parts) M
EK/Acetone (2/1) 600 copies A manuscript film was placed tightly on the obtained plate, and using an ultra-high pressure mercury lamp,
Exposure was performed at 400 mJ/cJ. The original film was removed and immersed in Isopar E (manufactured by Etsuji Chemical Co., Ltd.) containing 10% ethyl alcohol for 30 seconds, and then a scrubber was added to remove the silicone rubber in the unexposed areas and expose the aluminum background.

When the plate obtained in this way was printed using Heidel GT○ (manufactured by Heidel) with the dampening water supply device removed, the ink was Acquares Five ink TPM manufactured by Toyo Ink Manufacturing ■, and there was no scuffing. 10 good prints that do not cause
I was able to get 000 pieces.

(Comparative Example-1) A lithographic printing plate (
n) was obtained.

This lithographic printing plate (n) and the non-image area of the lithographic printing plate (1) of Example 1 were tested with a continuous weight scratch strength tester Type-HEIDON-18 manufactured by Shinrai Kagaku ■ Co., Ltd. with a diameter of 0.
The wound was made using a 4 mm sapphire needle with a load of 400 g.

When this was printed in the same manner as in Example 1, lithographic printing plate (I) had no background smudge at all, whereas lithographic printing plate (II) had scratch-like background smear.

(Comparative Example 2) In Example 1, instead of the diazo resin ~110, 15 parts of 4 mol/emole addition of glycidyl methacrylate and xylylene dianine and 1 part of menziine isobutyl ether were added.
The resulting mixture was coated to obtain a lithographic printing plate (III).

When this was plate-made and printed in the same manner as in Example 1, the lithographic printing plate (1) showed no scuffing at all until 10,000 sheets were printed, whereas the lithographic printing plate did not have scumming after 2,000 sheets. occurred, and the small dots disappeared after 5,000 sheets were printed.

(Comparative Example 3) Instead of the substrate-1 of Example-1, the substrate-2, which was not subjected to the sodium silicate treatment, was used.

When the same photosensitive liquid as in Example 1 was applied, the plate was made, and the plate was run on a printing press, the small dots disappeared after 200 sheets were printed.

(Example 2) The following photosensitive layer was dispersed in MEK/acetone and coated on the substrate-1 of Example, and then dried at 100°C for 12 minutes.

After that, it was heated at 55°C for 20 hours, and the thickness was 5g/
A photosensitive lithographic printing plate (IV) with a size of 1.5 m'' and which does not require dampening water was obtained.

(a) Toshi Silicone PRX-305 100 parts (b) Methyltri (methyl ethyl ketoxime)
Silane 2 parts (C) Diptyltin diacetate 0.2 parts (d) Diazo resin
15 parts (e) Aerosil R-9722 parts (f) MEK/
Acetone (2/1) 400 copies When exposed and plate-made in the same manner as in Example 1 and printed under the same conditions, more than 10,000 good prints without background smudge could be obtained.

(Example 3) An aluminum plate was treated with sodium silicate at 3 ht% and 90° C. for 160 seconds, and then washed with water.

(Substrate-2) The following photosensitive layer was dispersed in MEK/acetone and coated on this substrate-2, and then dried at 100°C for 12 minutes.

After that, it was heated at 55°C for 20 hours, and the thickness was 5g/
A dampening water-free photosensitive printing plate (V) of m2 was obtained.

(a) Organopolysiloxane KS837 (addition type > 50 parts (+)) manufactured by Shin-Etsu Chemical ■ Organopolysiloxane 5H-781 manufactured by Toshi Silicone
(Condensed type) 50 parts (C) Shin-Etsu Chemical Co., Ltd., Nrankasobling agent KBE-135 parts (ci) Shin-Etsu Chemical Co., Ltd., platinum-based addition catalyst CAT
-RG O, 1 part (manufactured by eJ B Hon Aerosil ■ Aerosil R97210 parts (f) Diazo resin - 210 parts (g) MEK/7cm) 7 (2/1) 600 parts Exposure and development in the same manner as in Example 1 did. When printing was carried out using an offset printing machine with the dampening water supply device removed, 5,000 sheets of good quality printed matter without soiling could be obtained.

(Comparative Example 4) Instead of Example 3, the same photosensitive solution was applied to Substrate 3, which had not been treated with sodium silicate, to obtain a photosensitive lithographic printing plate (2) having a thickness of 5 μm and requiring no dampening water.

When exposed and developed in the same manner as in Example 1, the small dots in the developed image area disappeared.

Applicant Mitsubishi Kasei Corporation: 1 person

Claims (1)

[Claims] (1) A photosensitive lithographic printing plate that does not require dampening water and is characterized in that a photosensitive layer containing silicone rubber, diazo resin, and an inorganic filler as main components is provided on a substrate whose surface has been anionized.