JPH04243260A - Damping waterless photosensitive planographic printing plate - Google Patents

Abstract

PURPOSE:To obtain the excellent image reproducibility and the resistance to scratch and to prevent the bleeding by incorporating a hydroxy group containing polymer and a diazo resin in the photosensitive layer and incorporative a specified polydimethyl siloxane in the silicone rubber layer. CONSTITUTION:The damping waterless photosensitive planographic printing plate having at least a primer layer, a photosensitive layer and a silicone rubber layer in order on the base plate, at least the hydroxy group containing polymer and the diazo resin are incorporated as the essential component in the photosensitive layer. Besides in the silicone rubber layer, dimethyl siloxane being trimethyl sililated in both the terminals, and being >=10,000 of the weight average molecular weight, is incorporated at 2-15wt.%. The diazo resin is obtained to condense a diazo compound and an active carbonyl compound in an acidic medium such as hydrosulfuric acid, phosphoric acid and hydrochloric acid. Also as the hydroxy group containing polymer, an ester or amide of alcoholic hydroxy group containing poly (meth)acrylic acid is preferred.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a photosensitive lithographic printing plate that does not require dampening water, and more specifically to a dampening water-reducing plate comprising a primer layer, a photosensitive layer, and a silicone rubber layer coated in this order on a substrate. This invention relates to a water-free photosensitive lithographic printing plate.

0002

BACKGROUND OF THE INVENTION In recent years, attempts have been made to develop photosensitive lithographic printing plates that do not require dampening water. A dampening water-free photosensitive lithographic printing plate is disclosed which has a structure in which a silicone layer is provided on a photosensitive layer on a support, and when the photosensitive layer is dissolved in a developer, the upper silicone rubber layer is removed and an image is formed. A plate making method for forming line portions is disclosed. Furthermore, Japanese Patent Publication Nos. 54-26923 and 56-23150 have a similar structure to the above in that a silicone rubber layer is provided on a photosensitive layer on a support, but the photosensitive layer does not require a developing solution. A method has been disclosed in which the silicone rubber layer is selectively swelled and removed by causing photo-adhesion or photo-separation between the photosensitive layer and the silicone rubber layer through image exposure without being dissolved in the silicone rubber layer.

[0003] Furthermore, Japanese Patent Publication No. 61-54219, Japanese Patent Publication No. 6
No. 0-229031 and No. 62-194255 disclose photosensitive lithographic printing plates that do not require dampening water and have a structure in which a photosensitive layer and a silicone layer are provided on a primer layer on a support.

The methods disclosed in Japanese Patent Publications No. 44-23042 and No. 46-16044 can increase the adhesive strength between the silicone rubber layer and the photosensitive layer, and between the support and the photosensitive layer, and improve image quality and printing durability. Although a printing plate with excellent force and scratch strength can be expected, the printing area inevitably becomes a relatively deep recess, and there is a problem in that it has to be thickly plated in order to have sufficient ink adhesion. Also,
Special Publication No. 54-26923 and No. 56-23150
The method described in the publication can avoid the above-mentioned disadvantages of ink build-up, but since it utilizes the delicate adhesion between the silicone rubber layer and the photosensitive layer, it is difficult to design the silicone layer and has problems with scratch strength and image reproducibility. There was a problem.

Furthermore, although the method disclosed in JP-A No. 60-229031 improves the above-mentioned drawbacks, it still has the drawbacks of poor dyeability of the primer layer and insufficient adhesion between the photosensitive layer and the primer layer. JP-A-61-54219 and JP-A-62-194255.
The method described in the publication had the drawback that the primer layer was mainly thermally crosslinkable and was cured by heating after being applied onto the support, resulting in poor production efficiency and being economically disadvantageous. .

[0006] In order to improve the above-mentioned drawbacks, the present inventors proposed a dampening solution in which the photosensitive layer contains a diazo resin and a methacrylic acid ester having a hydroxyl group or an amide-containing polymer. A water-free photosensitive lithographic printing plate was proposed, and in Japanese Patent Application No. 2-077717, in addition to the above-mentioned photosensitive layer, a silicone rubber layer contained a low molecular weight organopolysiloxane, thereby eliminating the above-mentioned drawbacks. We proposed a method to improve the deterioration of image reproducibility, which is a newly occurring problem, and were able to obtain certain effects.

[0007]

[Problems to be Solved by the Invention] However, when using a low molecular weight organopolysiloxane as described above,
During or after the production of a photosensitive lithographic printing plate that does not require dampening water, the organopolysiloxane leaches out,
This has caused various problems. Further, such a photosensitive lithographic printing plate that does not require dampening water has the disadvantage that it cannot sufficiently improve the scratch strength, that is, the scratch resistance.

[0008] Accordingly, an object of the present invention is to provide a photosensitive lithographic printing plate that does not require dampening water and is free from bleeding and has excellent scratch resistance while maintaining excellent image reproducibility.

[0009]

[Means for Solving the Problems] In view of the above-mentioned problems, the present inventors have conducted intensive research and found that the above-mentioned object of the present invention is to provide at least a primer layer, a photosensitive layer and a silicone rubber layer on a substrate from the substrate side. In a photosensitive lithographic printing plate that does not require dampening water, the photosensitive layer contains at least a hydroxyl group-containing polymer and a diazo resin, and the silicone rubber layer has trimethylsilylation at both ends and has a weight average molecular weight of 10,000 or more. of polydimethylsiloxane from 2 to
It has been found that this can be achieved by providing a photosensitive lithographic printing plate that does not require dampening water and is characterized in that it contains 15% by weight.

The present invention will be explained in more detail below.

The photosensitive layer used in the present invention contains a diazo resin and a hydroxyl group-containing polymer as essential components.

Examples of the diazo resin include those described in Photographic Science and Engineering (Photo.Sci.Eng.), Vol. 17, p. 33 (1973), US Patent No. 2,063,631, US Pat. Diazo compounds and active carbonyl compounds (for example, formaldehyde, acetaldehyde or benzaldehyde etc.) in an acidic medium such as sulfuric acid, phosphoric acid, or hydrochloric acid.
A diazo resin obtained by condensing a diazo compound and a diphenyl ether derivative, the manufacturing method of which is described in Publication No. 4001, can be used. Particularly preferred is a condensate of paradiazodiphenylamine and formalin.

The counter anion of the diazo resin used in the present invention includes an anion that forms a stable salt with the diazo resin and makes the resin soluble in an organic solvent. These include organic carboxylic acids such as decanoic acid and benzoic acid, organic phosphoric acids such as phenylphosphoric acid, and sulfonic acids; typical examples include methanesulfonic acid, chloroethanesulfonic acid, dodecanesulfonic acid, benzenesulfonic acid. , toluenesulfonic acid, mesitylenesulfonic acid and anthraquinonesulfonic acid, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid, hydroquinonesulfonic acid, 4
- Aliphatic and aromatic sulfonic acids such as acetylbenzenesulfonic acid and dimethyl-5-sulfoisophthalate, 2
, 2',4,4'-tetrahydroxybenzophenone,
1,2,3-trihydroxybenzophenone, 2,2'
, 4-trihydroxybenzophenone, halogenated Lewis acids such as hexafluorophosphoric acid and tetrafluoroboric acid, and perhalogen acids such as ClO4 and IO4. Among these, halogenated Lewis acids are preferred, and hexafluorophosphoric acid is particularly preferred. The weight average molecular weight of the coupled product with β-naphthol measured by gel permeation chromatography (GPC) is preferably in the range of 200 to 10,000 (in terms of styrene), more preferably in the range of 500 to 5,000.

In the present invention, the proportion of the diazo resin in the photosensitive layer is usually 1 to 90% by weight, and 3 to 60% by weight.
is preferred.

Further, as the hydroxyl group-containing polymer in the present invention, an ester or amide of alcoholic hydroxyl group-containing poly(meth)acrylic acid is preferably used.

In the present invention, when an acrylic compound and a methacrylic compound are referred to below, they will be written as "(meth)acrylic...".

Examples of the monomer having an alcoholic hydroxyl group include 2-hydroxyethyl acrylate and 2-hydroxyethyl acrylate.
Hydroxyethyl methacrylate, N-(4-hydroxyethylphenyl)methacrylamide, hydroxy-methyldiacetone (meth)acrylamide, and the like. In particular, 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate are preferably used.

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, o-, m-, p
-Hydroxystyrene, o-, m-, p-hydroxyphenyl acrylate or -methacrylate, (2) α, β- of acrylic acid, methacrylic acid, maleic anhydride, etc.
Unsaturated carboxylic acid, (3) Methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, amyl acrylate, hexyl acrylate, octyl acrylate, acrylic acid-
(Substituted) alkyl acrylates such as 2-chloroethyl, 2-hydroxyethyl acrylate, glycidyl acrylate, N-dimethylaminoethyl acrylate, (4
) (Substituted) alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, amyl methacrylate, cyclohexyl methacrylate, 2-hydroxyethyl methacrylate, 4-hydroxybutyl methacrylate, glycidyl methacrylate, N-dimethylaminoethyl methacrylate, (5 ) Acrylamide, methacrylamide, N-methylolacrylamide, N-methylolmethacrylamide, N-ethylacrylamide, N-hexylmethacrylamide, N-cyclohexylacrylamide, N-hydroxyethylacrylamide, N-phenylacrylamide, N-nitrophenylacrylamide, Acrylamides or methacrylamides such as N-ethyl-N-phenylacrylamide, (6) Vinyl ethers such as ethyl vinyl ether, 2-chloroethyl vinyl ether, hydroxyethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, octyl vinyl ether, phenyl vinyl ether, (7) ) Vinyl esters such as vinyl acetate, vinyl chloroacetate, vinyl butyrate, vinyl benzoate, etc. (8) Styrenes such as styrene, α-methylstyrene, methylstyrene, chloromethylstyrene, (9) Methyl vinyl ketone, ethyl Vinyl ketones such as vinyl ketone, propyl vinyl ketone, phenyl vinyl ketone, (10) olefins such as ethylene, propylene, isobutylene, butadiene, isoprene, (11) N-vinylpyrrolidone, N-vinylcarbazole, 4-vinylpyridine, Examples include acrylonitrile, methacrylonitrile, and the like. In particular, compounds (1) to (4) are preferred.

The amount of the hydroxyl group-containing monomer in the hydroxyl group-containing polymer is not particularly limited, but is preferably 5 to 5.
It is 100% by weight, particularly preferably 20 to 100% by weight.

The weight average molecular weight of the hydroxyl group-containing polymer of the present invention measured by GPC method is 5,000 to 1,000,000 (
styrene equivalent) is preferred. If the value is lower than 5,000, the coating solvent or developer of the photosensitive layer may be attacked even after photocuring, and if the value is higher 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 usually 10 to 99% by weight, preferably 40 to 9% by weight.
It is 7% by weight.

The weight ratio of the diazo resin to the hydroxyl group-containing polymer is preferably in the range of 1/99 to 90/10.

[0023] When the diazo resin is less than 1/99,
Even after photocuring, it may not be sufficiently crosslinked and may be damaged by the coating solvent or developer. On the other hand, if the diazo resin is more than 90/10, the polymer ratio will inevitably be smaller and the hydroxyl group content will be lower. Adhesion with the silicone layer tends to decrease.

The photosensitive layer of the present invention may also contain other photoinsolubilizable photosensitive substances, such as compounds having an addition polymerizable vinyl group.

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

Furthermore, in the photosensitive layer of the present invention, in addition to the materials described above, dyes, pigments, exposed visible image agents, coating property improvers, etc. may be added as necessary to improve the developable visible image property,
Exposure visibility and coating properties can be improved.

Examples of the above dyes include Victoria Pure Blue BOH, Oil Blue #603, Oil Pink #312, Patent Pure Blue, Crystal Violet, Leuco Crystal Violet, Brilliant Green, Ethyl Violet, Methyl Green, Erythrosine B, Basic Fuchsin, Triphenylmethane type, represented by 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 diphenylmethane-based, oxazine-based, xanthene-based, iminonaphthoquinone-based, azomethine-based, and anthraquinone-based dyes.

The above dye is usually contained in the photosensitive layer in an amount of about 0.01 to
It is preferred to contain about 10% by weight, preferably about 0.05-8% by weight.

As the coating property improver, alkyl ethers (for example, ethyl cellulose, methyl cellulose), fluorine-based surfactants, nonionic surfactants (for example, Pluronic L-64 (manufactured by Asahi Denka)), FC-430, etc.
(manufactured by Sumitomo 3M), etc.

[0030] Examples of exposure-visible agents include oxadiazole compounds described in JP-A-54-74728 and triazine compounds described in JP-A-53-36223. .

In the present invention, the thickness of the photosensitive layer is 0.1 m.
g/dm2 to 30mg/dm2 is preferable, and 0.5mg
/dm2 to 10mg/dm2 is more preferable.

In the present invention, a silicone rubber layer is provided on the photosensitive layer, and the silicone rubber layer contains polydimethylsiloxane having a weight average molecular weight of 10,000 or more and trimethylsilylated at both ends. Contains. In particular, the weight average molecular weight is 10,000 to 50,0
00 is preferred.

Although such polydimethylsiloxane can be used as a single polymer, it is preferable to use a mixture of two or more types of polydimethylsiloxane from the viewpoint of image reproducibility and the like.

Such polydimethylsiloxane is generally represented by the following structural formula (I).

[0035]

[Formula 1] In the formula, R1 and R2 are each an alkyl group, an aryl group, an alkenyl group, which may have a substituent such as a cyano group, a halogen atom, or a hydroxyl group, or a combination thereof, and are a methyl group, a phenyl group, or a vinyl group. A trifluoropropyl group is preferred, and a methyl group is particularly preferred.

The polydimethylsiloxane which is trimethylsilylated at both ends and has a weight average molecular weight of 10,000 or more used in the present invention is contained in the silicone rubber layer in an amount of 2 to 15% by weight, preferably 3 to 12% by weight.

In the present invention, in addition to the polydimethylsiloxane described above, other organopolysiloxanes having a molecular weight of usually 1,000 to several hundreds of thousands can be used in the silicone rubber layer. Such organopolysiloxanes are generally represented by the above structural formula (I) and are classified into condensed type and addition type depending on the method of crosslinking.

[0038] In the condensed type, crosslinking is performed by a condensation reaction, and water, alcohol, organic acid, etc. are released by the reaction. Particularly useful condensation type silicone rubbers include a mixture of a linear organopolysiloxane having hydroxyl groups at both ends or a part of the main chain and a silicone crosslinking agent, or one in which the hydroxyl groups are reacted with a silicone crosslinking agent.
In either case, adding a condensation catalyst is advantageous in terms of crosslinking speed.

The above-mentioned silicone crosslinking agent is a so-called acetic acid-removed type, a de-acetic acid type, which has a group represented by the following structural formula or a functional group represented by -OH (in the formula, R and R' are each an alkyl group). Examples include condensation type silicone crosslinking agents such as oxime type, dealcohol type, deaminated type, and dehydrated type.

[0040]

embedded image Examples of such crosslinking agents include tetraacetoxysilane, methyltriacetoxysilane, ethyltriacetoxysilane, phenyltriacetoxysilane, dimethyldiacetoxysilane, diethyldiacetoxysilane, vinyltriacetoxysilane, and methyltriacetoxysilane. methoxysilane,
Examples include dimethyldimethoxysilane, vinyltrimethoxysilane, methyltris(acetoneoxime)silane, methyltri(N-methyl, N-acetylamino)silane, vinyltri(methylethylketoxime)silane, methyltri(methylethylketoxime)silane or oligomers thereof. can.

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

Examples of the condensation catalyst include organic tin carboxylic acid esters, titanic acid esters, naphthenic acids, and the like.

The addition type refers to one in which hydrogen 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, examples include vinyl group-containing organopolysiloxanes, hydrogenated organopolysiloxanes, and the like mixed with platinum-based catalysts (for example, chloroplatinic acid). The organopolysiloxane has repeating units similar to those of the condensed type in the main chain.

[0044] 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 commercially available silicone rubbers, preferred examples include "KS-705F", "KE-41", and "KE-4" manufactured by Shin-Etsu Co., Ltd.
2”, “KE-44”, Toshiba Silicone (manufactured by YE5)
505", "YF3057", Toray Silicone (manufactured by) "
SH-781", "PRX-305", "SH-237
” and other condensation silicone rubbers, and Shin-Etsu Co., Ltd.'s KS-
837”, “KE-103”, “KE-106”, “K
E-1300'', Toshiba Silicone (manufactured by TSE-30)
32", "RTU-B", Toray Silicone (manufactured by SH)
Examples include addition type silicone rubber such as "-9555".

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 viewpoint of image quality and developability;
On the contrary, a certain degree of thickness is required from the viewpoint of printing stains, etc., so generally, 3 mg/dm2 to 50 mg/dm2 is preferable, and 5 mg/dm2 to 30 mg/dm2 is more preferable.

In the present invention, a primer layer is provided between the above-mentioned photosensitive layer and the substrate.

As the primer layer, any of various known primer layers can be applied, but for example, epoxy resin,
Primer layers described in Japanese Patent Publication No. 61-54219, such as polyurethane resins heated and cured using an appropriate curing agent, or special materials, such as those made by photocuring a layer made of a photodimer type curable resin, etc. The primer layer described in JP-A No. 60-229031 can be used. Furthermore, a primer layer obtained by photocuring a layer mainly composed of a diazo resin and a hydroxyl group-containing polymer is also used.

In the present invention, a primer layer containing a binder, an ethylenically unsaturated monomer or oligomer, and a photopolymerization initiator is preferably used. As the binder, polyester, polyurethane, polyester urethane, acrylic resin, polyamide, gelatin, cellulose, etc. are preferably used.

The proportion of the binder in the primer layer is usually 10 to 99% by weight, preferably 40 to 97% by weight.

[0051] The ethylenically unsaturated monomer or oligomer is a compound having a boiling point of 100°C or more under normal pressure and containing two or more polymerizable terminal ethylene groups, and various known ones can be used. For example, 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 polyhydric carboxylic acids, and the aforementioned aliphatic polyhydroxy compounds. Examples include esters obtained by esterification reactions with polyhydric hydroxy compounds such as hydroxy compounds and aromatic polyhydroxy compounds. (meth)acrylate, triethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate,
Examples include pentaerythritol triacrylate, hydroquinone di(meth)acrylate, pyrogallol triacrylate, and 2,2'-bis(4-acryloxy-diethoxyphenyl)propane. Others include ethylene bis(meth)acrylamide, hexamethylene bis(
(meth)acrylamides such as meth)acrylamide;
Alternatively, vinyl urethane compounds, epoxy (meth)acrylates, etc. can be mentioned.

In the present invention, the amount of the ethylenically unsaturated monomer or oligomer in the primer layer is 10
~90% by weight, preferably 20-80% by weight.

[0053] As the photopolymerization initiator, conventionally known ones can be used, and for example, benzoin, benzoin alkyl ether, benzophenone, anthraquinone, benzyl, Michler's ketone, a complex system of hiimidazole and Michler's ketone, etc. are preferably used. Can be done.

The amount of the photopolymerization initiator in the primer layer is 0.1 to 20% by weight, preferably 0.2 to 10% by weight.

In the photosensitive lithographic printing plate which does not require dampening water of the present invention, the primer layer may contain, in addition to the above components, a silane coupling agent containing an amino group or an epoxy group.

In the present invention, in addition to the above-mentioned components, the primer layer may contain other fillers or antihalation agents, coloring agents such as dyes and pigments, coating properties improvers, plasticizers, stabilizers, and oil sensitizers as required. It may also contain a curing agent or the like in an amount not exceeding 10% by weight.

The dye and coating improver that can be included in the primer layer are the same as those used in the photosensitive layer.

Examples of the plasticizer for imparting flexibility and abrasion resistance to the coating film include butylphthalyl, polyethylene glycol, tributyl citrate, diethyl phthalate,
Dibutyl phthalate, dihexyl phthalate, dioctyl phthalate, tricresyl phosphate, tributyl phosphate, trioctyl phosphate, tetrahydrafurfuryl oleate,
Examples include oligomers of acrylic acid or methacrylic acid.

In addition, in order to improve the printing ink adhesion of images, various additives having hydrophobic groups, such as p-octylphenol formalin novolac resin, p-t-butylphenol formalin novolak resin, p-t-
Modified novolac resins such as butylphenol benzaltehyde resin and rosin-modified novolak resin, and o-naphthoquinonediazide sulfonic acid esters (esterification rate of OH group 20 to 70 mol%) of these modified novolak resins can be added and used. can.

[0060] When the above primer composition contains a pigment, it is optionally dispersed in a suitable organic solvent by a known dispersion method (SGI, homogenizer, etc.) and then filtered. After coating the dispersion on a support and drying it,
A primer layer is formed by photocuring.

For photocuring, a known light source such as a mercury lamp, a xenon lamp, or natural light is used, and the amount of exposure (usually, for example, 50 mJ/cm2 to 5 J/c) is sufficient to harden the primer layer.
This can be done by exposing to light within a range of m2. Further, it is desirable that the curing is carried out at least before the coating of the photosensitive layer is completed, and more preferably immediately after coating.

In the present invention, the thickness of the primer layer is 1
It is preferably from mg/dm2 to 500mg/dm2, more preferably from 3mg/dm2 to 300mg/dm
It is 2.

Furthermore, the photosensitive lithographic printing plate that does not require dampening water of the present invention may have a protective layer provided on the silicone rubber layer, and a method for providing the protective layer is a polypropylene film described in Japanese Patent Publication No. 61-614. A method of laminating the like, a method of coating a high molecular weight polymer described in JP-A No. 61-27545, etc. are known.

[0064] The substrate used in the present invention is as follows:
Any material can be used as long as it has the flexibility to be set in a normal lithographic printing machine and can withstand the load applied during printing, and there are no particular limitations, including the layer structure. Examples include papers such as coated paper, metal plates such as aluminum plates, and plastic films such as polyethylene terephthalate. In the present invention, the substrate is an aluminum plate or
Aluminum foil and other composite materials are preferred, and aluminum plates are particularly preferred from the viewpoint of printing durability.

After imagewise exposing the photosensitive lithographic printing plate prepared as described above, the photosensitive layer was developed with a developer to dissolve it and removed together with the silicone rubber layer thereon. As a result, the base plate or primer layer formed an image. A waterless plate is formed. In this case, it is preferable to dye the image area with a cationic dye such as crystal violet or Victoria blue BOH during or after development.

The light source used for exposure is 180n
Any general-purpose light source including ultraviolet rays and visible rays with a wavelength of more than m may be used, but carbon arc lamps, mercury lamps, xenon lamps, metal halide lamps, strobes, etc. are particularly preferred.

[0067] As the developer used in the development process, a solution prepared by adding an organic solvent, an alkaline compound such as an amine or a silicate, a surfactant, and further hydrocarbons as necessary to water is used. .

Development can be carried out by various known methods, 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.

[0069]

EXAMPLES The present invention will be explained in more detail with reference to examples below, but the present invention is not limited to the following examples.

(Synthesis of Diazo Resin-1) 14.5 g of p-diazodiphenylamine sulfate was dissolved in 40.9 g of concentrated sulfuric acid under ice cooling. 1.0 g of paraformaldehyde was slowly added dropwise to this reaction solution so that the reaction temperature did not exceed 10°C. Thereafter, stirring was continued for 2 hours under ice cooling. This reaction mixture was added dropwise to 500 ml of ethanol under ice cooling, and the resulting precipitate was filtered. After washing with ethanol, this precipitate was dissolved in 100 ml 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 ml of 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 then dried at 30°C all day and night to obtain diazo resin-1.

[0071] The diazo resin had a weight average molecular weight (Mw) of 1,500 and a number average molecular weight of 500 in terms of styrene, as measured by GPC method.

Example 1 The following primer layer composition was coated on a degreased original plate with a thickness of 0.24 mm at 60°C using a whirler, and after drying at 100°C for 4 minutes, it was heated to 1000 mJ using a 3KW ultra-high pressure mercury lamp.
A primer layer was provided by exposing the entire surface to light of /cm2. The dry film thickness was 130 mg/dm2.

The primer layer composition was dispersed using a high-pressure bulb homogenizer. Note that parts used below refer to parts by weight. (Primer layer composition) (1) 2-hydroxyethyl methacrylate,
Molar ratio of methyl methacrylate 34/66
Copolymer resin (Mw=4.0×104)
100 parts (2) Pentaerythritol triacrylate 60 parts

[0074]

[Chemical formula 3] (6) KET-YELLOW 402 (yellow pigment manufactured by Dainippon Ink Co., Ltd.)
8 parts (7) Zinc oxide (average particle size: 0
．． 12 μm) 20 parts (8
) Methyl lactate
After coating and drying 600 copies, exposure was performed using Unicure (manufactured by Ushio Inc.) at 160 W and 4 m/min.

Next, a photosensitive composition having the composition shown below was coated on the primer layer and dried at 100°C for 2 minutes to a thickness of 0.
．． A 3 μm thick photosensitive layer was formed. (Photosensitive composition) (1) Diazo resin-1
50 parts (2) Copolymer resin-2 (M
w=4.8×104)
50 parts (3) Victoria Pure Blue BOH (paint manufactured by Hodogaya Chemical Co., Ltd.)
Part 1 (4) Methyl cellosolve
900 parts of the following silicone rubber composition was then applied onto the photosensitive layer to a dry film thickness of 2 μm, and dried at 90° C. for 10 minutes. (Silicone rubber layer composition) Polydimethyl siloxane having hydroxyl groups at both ends (molecular weight 52,000)
100 parts triacetoxymethylsilane 10 parts dibutyltin laurate
0.8 parts 1,3,5-
Tri(trisilylpropyl) isocyanurate

2.5 parts Polydimethylsiloxane having trimethylsilyl groups at both ends
See Table 1 Isopar E
(Made by Esso Chemical)
900 partsNext, a 5μ thick single-sided matted polypropylene film was laminated on the silicone rubber layer,
Dampening water unnecessary photosensitive lithographic printing plate sample No. 1 to 7 were obtained.

After a positive film was vacuum-adhered to the upper surface of the above plate material, it was exposed to light using a metal halide lamp as a light source. Next, after performing standard development by immersing it in the following developer for 1 minute, the surface of the plate material is rubbed with a pad impregnated with the developer to remove the unexposed portions of the silicone rubber layer and the photosensitive layer. A printing plate with well reproduced halftone dots was obtained.

Furthermore, the image area of the above printing plate could be vividly dyed by applying a dyeing liquid of the following composition to a cloth, lightly rubbing the plate, and then washing with water. (Developer) β-anilinoethanol
0.5 part propylene glycol
1.0 part p-tert-butylbenzoic acid
1.0 part potassium hydroxide
1.0 part polyoxyethylene lauryl ether 0.1 part potassium sulfite 2
．． 0 parts potassium metasilicate
3.0 parts water
91 parts (staining solution) Rheodol TW-0120 (surfactant manufactured by Kao Corporation) 0.
5 parts benzyl alcohol
5.0 part Victoria Pure Blue BOH
1.0 part water
100 copies The leaching, scratch resistance and image reproducibility of each of the plates prepared as above were measured and evaluated using the following methods. Table 2 shows the results.
Shown below.

[0078]

[Table 1]

[0079]

[Table 2] 1) Tack: After heat curing, touch the silicone layer with your finger and judge whether a fingerprint is left. 2) Scratch resistance: Scratch resistance was evaluated using a continuous weight scratch strength tester Type-HEIDON 18 manufactured by Shinto Kagaku Co., Ltd. using a sapphire needle with a diameter of 0.2 mm on the printing plate in the non-printing area. 3) Image reproducibility: Place the Ugler chart on the printing plate in vacuum, and visually judge how well the image is reproduced after exposure, development, and dyeing.

As is clear from Table 2, Sample 1 of the present invention contains 2 to 15% by weight of polydimethylsiloxane having a weight average molecular weight of 10,000 or more and trimethylsilylated at both ends in the silicone rubber layer as in the present invention. ~4
Both are excellent in terms of tack, halftone reproducibility, and scratch resistance.

Example-2 Sample No. 2 in Example-1. The binder for the first primer layer is polyester urethane UR8300 manufactured by Toyobo Co., Ltd.
A plate was obtained in the same manner as in Example 1 except that the plate was changed to, and evaluated in the same manner.

In this example, as in Sample-1, good results were obtained with no tack, halftone dot reproducibility of 2 to 99%, and scratch resistance of 50 g.

Comparative Example-1 Sample No. of Example-1. A plate was prepared in the same manner as in Example 1, except that the binder copolymer resin-2 in the photosensitive layer No. 2 was changed to a copolymer resin with a molar ratio of methyl methacrylate/methacrylic acid of 90/10 (Mw = 5.2 x 104). The obtained image was evaluated in the same manner, but the image reproducibility was extremely poor.

[0084]

[Effects of the Invention] As described in detail above, the present invention provides a photosensitive lithographic printing plate that does not require dampening water and is free from bleeding and has excellent scratch resistance while maintaining excellent image reproducibility. can.

Claims (1)

[Claims] 1. A dampening water-free photosensitive lithographic printing plate having at least a primer layer, a photosensitive layer, and a silicone rubber layer in this order from the substrate side on a substrate, wherein the photosensitive layer contains at least a hydroxyl group-containing polymer and a diazo resin. and the silicone rubber layer contains 2 to 15% by weight of polydimethylsiloxane having a weight average molecular weight of 10,000 or more and trimethylsilylated at both ends. .