JPH0416946A - Original plate for planographic printing requiring no dampening water - Google Patents

Abstract

PURPOSE:To obtain the original plate for dampening waterless planographic printing which allows easy developing and simple production by using a polymer having polysiloxane in the side chain as the component of a photosensitive layer. CONSTITUTION:The polymer having the polysiloxane in the side chain is used as the component of the photosensitive layer of the original plate for dampening water less planographic printing constituted by providing with an ink repulsive layer and the photosensitive layer in this order on a substrate. Namely, the affinity to the silicone rubber of the photosensitive layer is enhanced and the coatability and adhesiveness of the photosensitive layer corresponding to the silicone rubber layer are improved by introducing the polysiloxane into the component of the photosensitive layer. The original plate for dampening waterless planographic printing which allows the easy development and the simple production is obtd. in this way.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a lithographic printing original plate that does not require dampening water. The present invention relates to a lithographic printing original plate that does not require dampening water and is provided with a moisturizing photosensitive layer in this order.

[Prior Art] Hitherto, there has been known a lithographic printing original plate that does not require dampening water and uses a silicone rubber layer as an ink repellent layer.

Japanese Patent Publication No. 44-23042, Japanese Patent Publication No. 46-16044, Japanese Patent Publication No. 54-26923, Japanese Patent Publication No. 6154222, Japanese Patent Publication No. 55-22781, etc. disclose that a photosensitive layer and a silicone rubber layer are formed on a substrate in this order. A lithographic printing original plate that does not require dampening water is disclosed. In these lithographic printing original plates, after exposure, the silicone rubber layer in the unexposed areas (image areas) is removed by development, and the underlying ink-receptive photosensitive layer is exposed to produce a printing plate. It is. In this case, silicone rubber has no photosensitivity, and it was necessary to remove the silicone rubber in the image area by physical force during the development process. Therefore, it has the disadvantage that the developing process is complicated and time-consuming.

Also, JP 60-42467, JP 61613, JP 55-47383, JP 61-19315
No. 5 and JP-A-1-1-73027 disclose a lithographic printing original plate that does not require dampening water and has a structure in which a silicone rubber layer and a photosensitive layer are substantially provided on a substrate in this order.

These lithographic printing original plates can be developed simply by dissolving and removing the ink-receiving photosensitive layer provided on the silicone rubber after exposure, and are very easy to develop. However, it is very difficult to provide a photosensitive layer by coating on the surface of silicone rubber, which has a very small surface free energy, in terms of coating properties and adhesion between the silicone rubber layer and the photosensitive layer. It had the disadvantage that the manufacturing process was complicated, such as by gluing together the silicone rubber layer coated uniformly on the film and the silicone rubber layer lined on the substrate, and then adhering the silicone rubber layer and the photosensitive layer.

[Problems to be Solved by the Invention] The present invention was devised in view of the current state of the prior art, and its purpose is to provide a lithographic printing original plate that is easy to develop and easy to manufacture and does not require dampening water. It is in.

[Means for Solving the Problems] The object of the present invention is to provide a lithographic printing original plate that does not require dampening water, which comprises an ink repellent layer and a photosensitive layer provided in this order on a substrate, and which uses polysiloxane as a component of the photosensitive layer. This is achieved by a lithographic printing original plate that does not require dampening water and is characterized by the use of a polymer contained in the side chain. That is, they discovered that by introducing polysiloxane into the photosensitive layer component, it is possible to increase the affinity of the photosensitive layer for silicone rubber, and that the coatability and adhesion of the photosensitive layer to the silicone rubber layer are improved. This led to the invention.

As the polysiloxane introduced into the side chain of the polymer contained in the photosensitive layer used in the present invention, any polysiloxane may be used as long as it has a high affinity with the silicone rubber that is the ink repellent layer. , have a structure as shown in formula (1).

1-u, n is an integer from 1 to 200, Rl, R2, R3
and R4 is a hydrogen atom, a vinyl group, an alkyl group having 1 to 10 carbon atoms, an alkoxy group, an aminoalkyl group, a mercaptoalkyl group, a haloalkyl group, a hydroxyalkyl group, a carboxyalkyl group having 2 to 10 carbon atoms, a cyanoalkyl group, It is one type selected from the group of an optionally substituted aryl group having 6 to 20 carbon atoms or an aralkyl group, and each group may be the same or different. A is a divalent organic group having 1 to 10 carbon atoms for bonding to the main chain, and B is a monovalent functional group, including a hydrogen atom, an optionally substituted silyl group, a hydroxyl group, a vinyl group, and a carbon number 1.
~10 alkyl groups, alkoxy groups, aminoalkyl groups, mercaptoalkyl groups, haloalkyl groups, hydroxyalkyl groups, carboxyalkyl groups having 2 to 10 carbon atoms,
Represents one member selected from the group consisting of a cyanoalkyl group, an optionally substituted aryl group having 6 to 20 carbon atoms, and an aralkyl group.

The polymer containing polysiloxane in its side chain, which is included in the photosensitive layer used in the present invention, can be obtained by polymerizing a polymerizable monomer containing polysiloxane. If necessary, it can be copolymerized with at least one other polymerizable monomer to form a copolymer. Another method for obtaining a polymer containing polysiloxane in its side chain is to chemically react a polymer having a reactive group with a polysiloxane having a functional group at the end that can react with the reactive group. Examples include a method in which the compound is bonded to the compound and introduced as a side chain.

The polymer containing polysiloxane in each chain used in the present invention may be of any type as long as it can sufficiently transmit light at the wavelength at which the photosensitive group contained in the photosensitive layer is sensitive. The structure of the main chain is preferably a polymer of ethylenically unsaturated compounds, polyurethane, polyester, etc., but is not limited thereto.

The main chain structure of the polymer is an ethylenically unsaturated compound, and the polymer containing polysiloxane in the side chain has a terminal functional group that can react with various ethylenically unsaturated compounds having a functional group. It is obtained by polymerizing a polysiloxane-containing monomer obtained by reacting a polysiloxane having a group. Examples of ethylenically unsaturated compounds include, but are not limited to, methacrylic acid derivatives, acrylic acid derivatives, styrene derivatives, vinyl acetic acid derivatives, vinyl ether derivatives, and the like.

As a combination of an ethylenically unsaturated compound having a functional group and a polysiloxane having a terminal functional group capable of reacting with the functional group, glycidyl (meth)acrylate (hereinafter, (meth)rororo means rororo or metalrororo) is used. ) and terminal aminopolysiloxane, or terminal carboxypolysiloxane: isocyanate propyl acrylate and terminal hydroxyl group polysiloxane, or terminal aminopolysiloxane: hydroxyethyl (meth)acrylate and terminal isocyanate polysiloxane, or terminal epoxypolysiloxane and parahydroxystyrene. Combinations such as terminal isocyanate polysiloxane, or terminal epoxy polysiloxane; (meth)acrylic acid and terminal epoxy polysiloxane, or terminal amino polysiloxane; and vinyl acetic acid and terminal epoxy polysiloxane, or terminal amino polysiloxane, etc. are mentioned.

Another method for obtaining a polymer whose main chain structure is an ethylenically unsaturated compound and which contains polysiloxane in the side chain is to obtain a polymer whose main chain is an ethylenically unsaturated compound and which contains polysiloxane in the side chain. For example, a polymer reaction between a polymer of methacrylic acid and a polysiloxane having a terminal functional group capable of reacting with the side chain of the polymer, such as a terminal epoxy polysiloxane or a terminal amino polysiloxane. In addition to the above-mentioned combinations, combinations of polymers of ethylenically unsaturated compounds and polysiloxanes having terminal functional groups include polymers of glycidyl (meth)acrylate and terminal aminopolysiloxanes, terminal carboxypolysiloxanes, or terminals. Phenol polysiloxane Polyacrylic acid polymer and terminal epoxy polysiloxane, or terminal aminopolysiloxane, isocyanate propyl acrylate polymer and terminal hydroxyl group polysiloxane, or terminal aminopolysiloxane; Hydroxyethyl (meth)acrylate polymer and terminal Epoxypolysiloxane or terminal isocyanate polysiloxane: combinations of parahydroxystyrene polymer and terminal isocyanate polysiloxane, or terminal epoxypolysiloxane may be mentioned, but are not limited thereto.

A polymer having a main chain structure of polyurethane and containing polysiloxane in the side chain is composed of a polysiloxane containing a diol at the end and at least one diisocyanate (for example,
hexamethylene diisocyanate, 4,4'-diphenylmethane diisocyanate, etc.). If necessary, at least one other diol (e.g. ethylene glycol, 1.
4-butanediol, etc.) for copolymerization or main chain extension. Polysiloxanes containing diol at the ends are, for example, polydimethylsiloxanes containing hydrosilyl groups at the ends and 3-allyloxy-1,
It can be obtained by a hydrosilylation reaction with 2-propanediol.

A polymer having a main chain structure of polyester and containing polysiloxane in the side chain is a polymer having at least one diol-terminated polysiloxane similar to that used in the synthesis of a polymer having a main chain structure of polyurethane. Seed dicarboxylic acid (
For example, it can be obtained by a polycondensation reaction with adipic acid, terephthalic acid, etc.). If necessary, other
Copolymerization can be carried out using at least one diol (eg, ethylene glycol, 1,4-butanediol, etc.).

The weight ratio of the polysiloxane portion of the polymer containing polysiloxane in the side chain used in the present invention is preferably 0.1 to 80% by weight, more preferably 5 to 50% by weight. If the proportion of the polysiloxane portion is too high, the ink receptivity of the photosensitive layer will decrease, and if it is too low, the affinity with the silicone rubber layer will decrease, and the coatability and adhesion of the photosensitive layer to the silicone rubber layer will decrease. do.

The photosensitivity of the photosensitive layer used in the present invention can be obtained by introducing a photocurable component into the photosensitive layer as a photosensitive component. The photosensitive component may be introduced into the polymer containing polysiloxane in the side chain in the form of a side chain, or may simply be mixed as a composition in the photosensitive layer. As the photosensitive component, known ones can be used. When introducing polysiloxane into a polymer containing a side chain, examples of functional groups that can be introduced include the following functional groups and their curing agents. A combination of these can be mentioned.

(1) Group having an unsaturated bond and photosensitizer Examples of the group having an unsaturated bond include a (meth)acryloyl group and its derivatives, a vinyl group and its derivatives, and the like. As the photosensitizer, benzophenone derivatives, benzoin derivatives, anthraquinone derivatives, aldehydes, ketones, sulfur compounds and halogen compounds, or dyes such as methylene blue and riboflavin can be used.

(2) Group having an unsaturated bond, trifunctional or higher functional thiol compound, and photoradical generator Examples of the group having an unsaturated bond include a (meth)acryloyl group, a vinyl group, and an allyl group. Examples of trifunctional or higher-functional thiol compounds include aliphatic dithiols, aromatic dithiols, esters of polyfunctional alcohols and mercaptocarboxylic acids, amides of polyfunctional amines and mercaptocarboxylic acids, esters of polyfunctional carboxylic acids and mercapto alcohols, and mercaptoalkyl groups. Polysiloxane containing in the side chain is used. As the photoradical generator, known photoradical polymerization initiators can be used, including peroxides such as peroxide to t-butyl and benzoyl peroxide, azo compounds such as azobisisobutyronitrile, benzoin derivatives, etc. can be used.

(3) A group having a mercapto group, a trifunctional or higher-functional unsaturated compound, and a photoradical generator As the group having a mercapto group, a mercapto group, a mercaptoalkyl group and its derivatives, a thiophenyl group and its derivatives, etc. are used.

Trifunctional or higher-functional unsaturated compounds are compounds containing two or more vinyl groups, allyl groups, (meth)acryloyl groups, etc., and include condensates of (meth)acrylic acid and polyhydric alcohols or polyhydric amines, ) Adducts of acrylic acid and polyfunctional epoxy compounds, adducts of glycidyl (meth)acrylate and polyhydric alcohols, polyvalent amines, polyvalent carboxylic acids, condensates of allyl alcohol and polyvalent carboxylic acids, allyl alcohol and a polyfunctional epoxy compound, a condensate of allyl halide and a polyhydric alcohol, and a polysiloxane containing a vinyl group in the side chain. As the photoradical generator, those listed in the previous section (2) can be used.

(4) Groups with epoxy groups and compounds that generate Lewis acids when exposed to light Groups with epoxy groups include epoxy groups, glycidyl groups, and derivatives thereof, such as polyalkylene chains and polysiloxanes with epoxy groups bonded to their terminals. This also includes chains. As the compound that generates a Lewis acid when exposed to light, boron tetrafluoride salts such as diazonium, iodonium, and sulfonium, phosphorus hexafluoride salts, and antimony hexafluoride salts can be used.

(5) Cinnamoyl group and photosensitizer As the photosensitizer, anthraquinone derivatives, acenaphthene derivatives, naphthalene derivatives, anthracene derivatives, fluorenone derivatives, etc. are used.

(6) Azide group and photosensitizer As the photosensitizer, pyrylium salt, thiapyrylium salt, etc. are used.

Further, the photosensitive component to be simply mixed into the photosensitive layer may include the following, but is not limited to these.

(1) Unsaturated monomers or their oligomers and photosensitizers Examples of unsaturated monomers include (meth)acrylic acid and its esters, (meth)acrylamides, styrenes, maleic acids and its esters. can be mentioned. As the photosensitizer, benzophenone derivatives, benzoin derivatives, anthraquinone derivatives, aldehydes, ketones, sulfur compounds, halogen compounds, or dyes such as methylene blue and riboflavin can be used.

(2) Trifunctional or more unsaturated compounds and trifunctional or more thiol compounds Trifunctional or more thiol compounds include aliphatic dithiols, aromatic dithiols, esters of polyfunctional alcohols and mercaptocarboxylic acids, polyfunctional amines and mercaptocarboxylic acids. Amides of carboxylic acids, esters of polyfunctional carboxylic acids and mercapto alcohols, polysiloxanes containing mercaptoalkyl groups in their side chains, polymers containing thiols in their side chains, and the like can be used. Trifunctional or higher-functional unsaturated compounds are compounds containing two or more vinyl groups, allyl groups, (meth)acryloyl groups, etc., and include condensates of (meth)acrylic acid and polyhydric alcohols and polyhydric amines, (meth) ) Adducts of acrylic acid and polyfunctional epoxy compounds, glycidyl (meth)acrylate and polyhydric alcohols, polyhydric amines,
Adducts with polycarboxylic acids, condensates of allyl alcohol and polycarboxylic acids, adducts of allyl alcohol with polyfunctional epoxy compounds, condensates of allyl halide with polyhydric alcohols, vinyl groups in side chains Polysiloxane and a polymer containing thiol in the side chain can be used.

(3) At least trifunctional or higher functional epoxy compounds and compounds that generate Lewis acids when exposed to light Trifunctional or higher functional epoxy compounds include aromatic or aliphatic compounds containing N or N diglycidylamino groups, and glycidyl (meth)acrylate. Polymers, copolymers (including oligomers) of glycidyl (meth)acrylate and ethylenically unsaturated compounds, polysiloxanes containing epoxy groups in side chains, and the like can be used.

As the compound that generates a Lewis acid when exposed to light, boron tetrafluoride salts such as diazonium, iodonium, and sulfonium, phosphorous hexafluoride salts, and antimony hexafluoride salts can be used.

(4) Photodimerizable photosensitive resin and sensitizer As the photodimerizable photosensitive resin, a polymer of vinyl cinnamate or a copolymer of vinyl cinnamate and an ethylenically unsaturated compound may be used. As the photosensitizer, anthraquinone derivatives, acenaphthene derivatives, naphthalene derivatives, anthracene derivatives, fluorenone derivatives, etc. are used.

(5) Organic solvent-soluble diazo resin As the organic solvent-soluble diazo resin, p-diazodiphenylamine or a derivative of p-diazodiphenylamine (for example, 3-methoxy-4-diazodiphenylamine, 4-methoxy-4-diazodiphenylamine, etc.) ) and formaldehyde or acetaldehyde, and a reaction product of hexafluorophosphate or tetrafluoroborate, or the condensate and phosphinic acid or a salt thereof, sulfonic acid or a salt thereof; 2
, 4-dihydroxybenzophenone, 2-hydroxy-
Examples include reaction products with hydroxyl group-containing compounds such as 4-methoxybenzophenone, 5-sulfonic acid, or salts thereof.

(6) Azide compound and cyclized rubber, azidophthalate or azidobenzoate of polyvinyl alcohol, or styrene-maleic anhydride copolymer and aromatic azido alcohol.

(7) An aromatic bisazide compound such as 4,4 diazido biphenyl, a cyclized rubber, and a 1-
Nitropyrene etc.

The silicone rubber used for the ink repellent layer of the present invention's dampening water-free lithographic printing original plate may be of any type as long as it exhibits ink repellency, but it is usually expressed by the general formula (2). It is possible to use a linear polysiloxane having a molecular weight of several thousand to several hundreds of thousands as shown, which is made into a rubber by crosslinking.

Here, n is an integer of 1 or more, Rl and R2 are hydrogen atoms,
Vinyl group, alkyl group having 1 to 10 carbon atoms, alkoxy group, aminoalkyl group, mercaptoalkyl group, haloalkyl group or hydroxyalkyl group, carboxyalkyl group having 2 to 10 carbon atoms, cyanoalkyl group, 6 to 10 carbon atoms
20 optionally substituted aryl groups or aralkyl groups, each of which may be the same or different.

Crosslinking methods include crosslinking the alkyl groups of polysiloxane using peroxide, and crosslinking silanol-terminated polysiloxane with polyfunctional silane compounds having hydrolyzable groups (acetoxy groups, alkoxy groups, ketoxime groups, etc.). Common methods include a method of crosslinking and a method of utilizing an addition reaction between a vinylsilyl group and a hydrosilyl group.

The substrate used in the lithographic printing original plate of the present invention may be any substrate as long as it gives the lithographic printing original plate shape retention and can withstand printing, such as a polymer film, metal plate, paper, or Composite materials of these materials are used.

The thickness of the photosensitive layer of the lithographic printing original plate of the present invention is 0°1 to 1
The thickness is preferably 0 μm, more preferably 0°3 to 5 μm. In addition, the thickness of the ink repellent layer is 0.5 to 100 μm.
More preferably, it is 1 to 50 μm.

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

Example 1 One-end methacryloyl polysiloxane (Shin-Etsu Chemical Co., Ltd.)
XX-22-174A) 50. 60 g of methyl methacrylate was copolymerized using azobisisobutyronitrile to obtain a polymer A containing polysiloxane in the side chain.

A room-temperature curing silicone gum composition having the following composition was placed on an aluminum plate in a grained chamber with a thickness of 0.24 mm to a dry film thickness of 3 μm.
It was coated using a bar coater so that the thickness of the film was 100 m. This was cured by heating at 100°C for 2 minutes to form a silicone rubber layer.

Dual-terminated silanol polysiloxane PS347.5 (manufactured by Chisso Corporation) 100 parts by weight Ethyltriacetoxysilane 12 parts by weight Toluene
325 parts by weight of a photosensitive layer solution having the following composition was applied onto the silicone rubber layer using a bar coater. This is 60'
It was dried at C for 2 minutes to form a photosensitive layer.

Polymer A 70 parts by weight "Aronix" M-310 (manufactured by Toagosei Kagaku Kogyo Co., Ltd.; photopolymerizable monomer) 30 parts by weight "Florado" FC-431 (manufactured by 3M) 5 parts by weight "Irgacure" 651 (Ciba Geigy) 5 parts by weight Toluene 400 parts by weight This photosensitive layer has a thickness of 2.5 μm and can be coated on the silicone rubber layer without any problem, and can easily be used as a lithographic printing original plate without the need for dampening water without any process such as gluing. I was able to get

A negative film was vacuum-adhered to the obtained lithographic printing original plate that did not require dampening water, exposed to light using a high-pressure mercury lamp, and then developed with toluene. It was found that the unexposed areas of the photosensitive layer were dissolved and removed without the need for physical force, and development could be easily achieved. Through this development, it was possible to obtain a printing plate that was faithful to the image on the negative film. When this printing plate was attached to a Hamata Star offset printing machine and offset printing was performed without using dampening water, a printed matter that faithfully reproduced the image on the negative film was obtained.

Example 2 50 g of methyl methacrylate, 4.3 g of methacrylic acid,
Polymerization was carried out in toluene using azobisisobutyronitrile to obtain a copolymer. 20 g of this copolymer and one-end epoxy polysiloxane (manufactured by Shin-Etsu Chemical Co., Ltd.; X-22-173)
A) 2.0g and 0.0g of triethylammonium chloride.
The reaction was carried out in dry tetrahydrofuran in the presence of 2 g to obtain Polymer B containing polysiloxane in the side chain.

On a grained aluminum plate with a thickness of 0.24 mm, a room temperature curing silicone gum composition having the following composition was applied to a dry film thickness of 5 μm.
It was coated using a bar coater so that the thickness of the film was 100 m. This was cured by heating at 100° C. for 2 minutes to form a silicone rubber layer.

Both terminal silanol polysiloxane PS343.8) (manufactured by Chisso Corporation) 100 parts by weight Ethyltriacetoxysilane 12 parts by weight Toluene
325 parts by weight of a photosensitive layer solution having the following composition was applied onto the silicone rubber layer using a bar coater. This is 60
It was dried at ℃ for 2 minutes to form a photosensitive layer.

Polymer B 70 parts by weight "Aronix" M-310 (manufactured by Toagosei Kagaku Kogyo Co., Ltd.; photopolymerizable monomer) 30 parts by weight "Florado" FC-43,1 (manufactured by 3M) 5 parts by weight "Irgacure" 651 (manufactured by Ciba Geigy) 5 parts by weight Toluene 400 parts by weight This photosensitive layer had a thickness of 2.0 μm and could be coated on the silicone rubber layer, making it possible to obtain a lithographic printing original plate that did not require dampening water.

A negative film was vacuum-adhered to the obtained lithographic printing original plate that did not require dampening water, exposed to light using a high-pressure mercury lamp, and then developed with toluene. The photosensitive layer in the unexposed areas was easily dissolved and removed, and a printing plate faithful to the image of the negative film could be obtained. When this printing plate was attached to a Hamada Star offset printing machine and offset printing was performed without using dampening water, a printed matter that faithfully reproduced the image of Negafim was obtained.

Example 3 Ring-opening polymerization of hexamethylcyclotrisiloxane was carried out in tetrahydrofuran using butyllithium as a catalyst. Excess dimethylchlorosilane was added to this polymerization solution to obtain polydimethylsiloxane containing hydrosilyl groups at the ends. This polydimethylsiloxane and 3-allyloxy-1°2-propanediol were reacted in toluene using platinum carbon as a catalyst to obtain polydimethylsiloxane containing diol at the terminal. By polycondensing polydimethylsiloxane containing this diol at the end with 4゜4'-diphenylmethane diisocyanate, and further elongating the main chain using 1,4-butanediol, the following formula (3) is obtained. As shown, a polymer C having a main chain structure of polyurethane and containing polysiloxane in the side chain was obtained. The number average molecular weight of the polysilosane portion of this polymer was 2,400.

A silicone rubber layer similar to that in Example 1 was provided on a grained aluminum plate having a thickness of 0.24 mm.

A photosensitive layer solution having the following composition was applied onto this silicone rubber layer using a bar coater. This was dried at 150°C for 2 minutes to form a photosensitive layer.

Polymer C70 parts by weight “Aronix” M-310 (Toagosei Chemical Industry Co., Ltd.)
(manufactured by photopolymerizable monomer) 30 parts by weight "Florado FC-431" (manufactured by 3M) 5 parts by weight "Irgacure" 651 (manufactured by Ciba Geigy) 5 parts by weight N, N-dimethylacetamide 400 parts by weight This photosensitive layer consisted of 2. It was possible to coat the silicone rubber layer to a thickness of 0 μm without any problem, and to obtain a lithographic printing original plate that did not require dampening water.

A negative film was vacuum-adhered to the obtained lithographic printing original plate that did not require dampening water, and after exposure with a high-pressure mercury lamp, N,
Development was performed with N-dimethylacetamide. The photosensitive layer in the unexposed areas was easily dissolved and removed, and a printing plate faithful to the image of the negative film could be obtained. When this printing plate was attached to a Hamatastar offset printing machine and offset printing was performed without using dampening water, a printed matter that faithfully reproduced the image of Negafim was obtained.

◎ =-2 0=CJ Example 4 By the same method as that used in Example 3, a polydimethylsiloxane containing a diol at the terminal and shown in formula (4) below was obtained. The number average molecular weight of this polysiloxane was 2,400.

By reacting polydimethylsiloxane containing this diol at the terminal with terephthalic acid, a polymer having a main chain structure of polyester and containing polysiloxane in the side chain was obtained.

A silicone rubber layer similar to that in Example 1 was provided on an aluminum plate in a grained chamber with a thickness of 0.24 mm.

A photosensitive layer solution having the following composition was applied onto this silicone rubber layer using a bar coater. This was dried at 150°C for 2 minutes to form a photosensitive layer.

Polymer D 70 parts by weight "Aronix" M-310 (manufactured by Toagosei Kagaku Kogyo Co., Ltd.; photopolymerizable monomer) 30 parts by weight "Florado" FC-431 (manufactured by 3M) 5 parts by weight "Irgacure" 651 (Ciba Geigy) 5 parts by weight of methyl ethyl ketone 400 parts by weight This photosensitive layer had a thickness of 1.5 .mu.m and could be coated on the silicone rubber layer without any problems, yielding a lithographic printing original plate that did not require dampening water.

A negative film was vacuum-adhered to the obtained lithographic printing original plate that did not require dampening water, exposed to light using a high-pressure mercury lamp, and then developed with methyl ethyl ketone. The photosensitive layer in the unexposed areas was easily dissolved and removed, and a printing plate faithful to the image of the negative film could be obtained. When this printing plate was attached to a Hamada Star offset printing machine and offset printing was performed without using dampening water, a printed matter that faithfully reproduced the image of Negafim was obtained.

[Effects of the Invention] Since the present invention is configured as described above, it is possible to obtain a lithographic printing original plate that is easy to develop, easy to manufacture, and does not require dampening water.

tJ　-0

Claims (1)

[Scope of Claims] 1. A lithographic printing original plate that does not require dampening water and has an ink repellent layer and a photosensitive layer provided in this order on a substrate, in which a polymer containing polysiloxane in the side chain is used as a component of the photosensitive layer. An original plate for planographic printing that does not require dampening water. 2. The fountain solution-free lithographic printing plate according to claim 1, wherein the main chain of the polymer containing polysiloxane in its side chain is a polymer of an ethylenically unsaturated compound. 3. The dampening water-free lithographic printing original plate according to claim 1, wherein the main chain of the polymer containing polysiloxane in its side chain is polyurethane. 4. The dampening water-free lithographic printing original plate according to claim 1, wherein the main chain of the polymer containing polysiloxane in its side chain is polyester.