JPH04172456A - Dampen water-free original plate for lithography - Google Patents

Abstract

PURPOSE:To obtain an original plate for printing which can be easily developed and in which the adhesive strength between a silicon rubber layer and a sensitive layer is strong and whose printing resistance is enhanced by using as components of the sensitive layer a polymer having hydroxyl group in its side chain and an alkanoyl oxyboron compound. CONSTITUTION:In a dampen water-free plate for lithography having a silicon rubber layer and a sensitive layer provided on a base in this sequence, the sensitive layer contains as its components a polymer having hydroxyl group in its side chain, and an alkanoyl oxyboron compound. Any polymer can be used as the one used in the sensitive layer and containing hydroxyl group in its side chain only if it allows transmission of a sufficient amount of light of the same sensitive wave length as a sensitizing group contained in the sensitive layer, and polymers of ethylene unsaturated compounds, polyurethane, polyester, polyamide and the like can be mentioned as examples of the structure of the main chain of the polymer. The side chain of the polymer which has hydroxyl group is normally a hydroxyl group itself or a univalent organic group having at least one hydroxyl group. Additionally, an alkanoyl oxyboron compound is contained as an essential component in the sensitive layer and the amount by which the compound is added is desirably 0.5 to 50 wt% or more desirably 1 to 30 wt% of the total components of the amount of sensitization.

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] A lithographic printing original plate that does not require dampening water and uses a silicone rubber layer as an ink repellent layer has been known.

Special Publication No. 44-23042, Special Publication No. 46-1. ,6044
, Special Publication No. 51-26923, Special Publication No. 61-54222,
Japanese Patent Publication No. 55-22781 discloses a lithographic printing original plate that does not require dampening water and has a photosensitive layer and a silicone rubber layer disposed in this order on a substrate.

In these lithographic printing original plates, after exposure, the silicone rubber layer in the unexposed areas (image areas) is removed by development.
A printing plate is prepared by exposing the underlying ink-receptive photosensitive layer. 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, the developing process is complicated and time-consuming.

In addition, special public service 60-42467, special public service 64-613,
Japanese Patent Publication No. 55-47383, Japanese Patent Publication No. 61-193155,
Japanese Unexamined Patent Publication No. 1-173027 discloses 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 by simply dissolving and removing the ink-receptive photosensitive layer provided on the silicone rubber after exposure.
Very easy to develop. However, since the photosensitive layer is provided on the surface of silicone rubber, which has a very small surface free energy, the adhesion between the silicone rubber layer and the photosensitive layer is very poor, resulting in insufficient printing durability. Was.

[Problems to be Solved by the Invention] The present invention was devised in view of the current state of the prior art, and its objectives are to provide easy development, strong adhesion to the photosensitive layer on the silicone rubber layer, and long printing life. An object of the present invention is to provide a lithographic printing original plate which does not require dampening water and has improved properties.

[Means for Solving the Problems] An object of the present invention is to provide a lithographic printing original plate that does not require dampening water, which comprises a silicone rubber layer and a photosensitive layer provided in this order on a substrate, in which the photosensitive layer has hydroxyl groups in side chains. This is achieved by a lithographic printing original plate that does not require dampening water and is characterized by containing as components a polymer containing an alkanoyloxyboron compound and an alkanoyloxyboron compound.

The silicone rubber layer used in the present invention includes:
Any known silicone rubber having ink repellency can be used. Usually, a linear polysiloxane with a molecular weight of several thousand to several hundred thousand, represented by -maximum (D), which is made into a rubber by crosslinking, is used.

R Engineering □ 1←SiO→Go (I) Here, n is an integer of 1 or more, R1, R,, are hydrogen atoms, vinyl groups, alkyl groups having 1 to 10 carbon atoms, alkoxy groups, aminoalkyl groups, mercapto an alkyl group, a haloalkyl group, a hydroxyalkyl group, a carboxyalkyl group having 2 to 1-0 carbon atoms, a cyanoalkyl group, an optionally substituted aryl group having 6 to 20 carbon atoms, or an aralkyl group, each of which They 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 of a hydrosilyl group to a vinylsilyl group.

The photosensitive layer of the present invention contains as a component a polymer containing a hydroxyl group in its side chain.

The polymer containing a hydroxyl group in its side chain used in the photosensitive layer of 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. As the chain structure, various structures can be used. Examples of main chain structures include polymers of ethylenically unsaturated compounds, polyurethane, polyester,
Examples include polyamide.

The side chain having a hydroxyl group in the polymer contained in the photosensitive layer of the present invention may be any type as long as it has a hydroxyl group, but it is usually a hydroxyl group itself or a monovalent side chain having at least one hydroxyl group. It is an organic group. Examples of the monovalent organic group having at least one hydroxyl group include the following.

R3 and R4 each represent a hydrogen atom, a halogen atom, a hydroxyl group, an amino group, an acyl group, a carboxy group, a cyano group, a nitro group, an alkyl group having 1 to 10 carbon atoms, an alkoxy group, or the like.

A is a group that connects the side chain and the main chain, and is an oxygen atom, a sulfur atom, -
NH-1 or a divalent organic group having 1 to 1-5 carbon atoms, R
5 and R6 each represent a hydrogen atom, a halogen atom, a hydroxyl group, an amino group, an acyl group, a carboxy group, a cyano group, a nitro group, an alkyl group having 1 to 10 carbon atoms, an alkoxy group, or the like.

-A-←CH2-1了OH A is a group that connects the side chain and the main chain, and is an oxygen atom, a sulfur atom, -
NH-1 or a divalent organic group having 1 to 15 carbon atoms, and n represents an integer of 1 or more.

-A-(-R7-O+-7-RToH A is a group that connects the side chain and the main chain; oxygen atom, sulfur atom, -
N H-1 or a divalent organic group having 1 to 15 carbon atoms, R
9 is an alkylene chain having 1 to 5 carbon atoms, R8 is an alkylene chain having 1 to 1 carbon atoms
5, a divalent organic group, and n represents an integer of 1 or more.

- D-(7S i O+-=RπOH□ R1゜D is a group connecting the side chain and the main chain, and is an oxygen atom or a divalent organic group having 1 to 15 carbon atoms, R1 and R1゜ are hydrogen atoms,
Vinyl group, alkyl group having 1 to 1 o carbon atoms, alkoxy group, aminoalkyl group, mercaptoalkyl group, haloalkyl group, hydroxyalkyl group, carboxyalkyl group having 2 to 1 o carbon atoms, cyanoalkyl group, 6 to 2 o carbon atoms
are optionally substituted aryl groups or aralkyl groups, which may be the same or different. R31 is a dimethylsilylene group, or
A divalent organic group having 1 to 15 carbon atoms, and n represents an integer of 1 or more.

Specific examples of polymers containing hydroxyl groups in their side chains include the following.

-+CH-CH,←+ CH-CH7士7COCH3C
Of
, n is an integer greater than or equal to 1) (-CH-CH2←"→CH-CJ12moτCH3CH
3 (1, m, n are integers of 1 or more) The photosensitive layer of the present invention contains an alkanoyloxyboron compound as an essential component in addition to the above-mentioned polymer containing a hydroxyl group in its side chain. The alkanoyloxyboron compound is a compound represented by the following general formula (■) or (III).

(R+2+-?-B-(-OCR+,i)!-,(n)
Here, a is an integer from O to 2, R1゜ is a hydroxyl group, and has 1 carbon number.
~10 alkyl group, alkoxy group, or 6 carbon atoms
~20 optionally substituted aryl groups, aryloxy groups, aralkyl groups, and R13 are alkyl groups having 1 to 1.0 carbon atoms.

\, -. hmm .

Here, R04 is a divalent alkylene group having 2 to 20 carbon atoms, and R15 is an alkyl group having 1 to 1 o carbon atoms.

Examples of alkanoyloxyboron compounds include triacetoxyboron, tripropionoyloxyboron, hydroxydiacetoxyboron, hydroxydipropionoyloxyboron, methoxydiacetoxyboron, methoxydipropionoyloxyboron, ethoxydiacetoxyboron, ethoxydipropyloxyboron, pionoyloxyboron,
n-propoxydiacetoxyboron, n-propoxydipropionoyloxyboron, isopropoxydiacetoxyboron, isoproboxydibrobionoyloxyboron, dimethoxyacetoxyboron, dimethoxypropionoyloxyboron, jetoxyacetoxyboron,
Jetoxypropionoyloxyboron, methyldiacetoxyboron, methyldipropionoyloxyboron,
Ethyldiacetoxyboron, ethylenepropionoyloxyboron, phenyldiacetoxyboron, phenyldipropiophyloxyboron, ethyleneacetoxyboron, ethylenepropionoyloxyboron, 1,2-propyleneacetoxyboron, 1-22-propylene Propionoyloxyboron, 2°? 1 Butylene acetoxyboron, 2.3-butylene-propionoyloxyboron, 1.3-propylene,'/acetoxyboron, 1
．． 3~propylenepro)-”-+/yloxyboron,
2,2-dimethylene, 9-1□; 3-propyleneacetoxyboron, 2,2-dimethy, 〆1. ．． ．． -, 1. ,
3-Propylenebrobionyl,): I'"
Examples include 7 elements.

伜：Addition of alkanoyloxyboron compound to the optical layer +j
ll [7,! : The content of the photosensitive layer is preferably from 5 to 50% by weight, more preferably from
<is] -=30% by weight.

The photosensitivity of the photosensitive layer used in the present invention is as follows:
It can be obtained by introducing a photocurable component into the photosensitive layer in step 1-1.The photosensitive component may be introduced in the form of a side chain into a polymer containing a hydroxyl group in the side chain (95 , may be simply mixed as a composition in the photosensitive layer 3. As the photosensitive component, known ones can be used 1. When introduced into a polymer containing a hydroxyl group in the side chain, it can be introduced. Examples of the functional group include the following combinations of the functional group and its curing agent.

(1) Groups with unsaturated bonds and photosensitizers Groups with unsaturated bonds include (meth)acryloyl groups (hereinafter, (meth)rororo refers to rororo or metalororo), derivatives thereof, and vinyl groups. and derivatives thereof. As the photosensitizer, benzophenone derivatives, benzoin derivatives, anthraquinone derivatives, aldehydes, ketones, sulfur compounds, halogen compounds, or dyes such as methidinone 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, an allyl group, and the like.

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, and benzoin derivatives. etc. can be used.

(3) A group having a mercapto group, a difunctional or higher unsaturated compound, and a photoradical generator. Examples of the group having a mercapto group include a mercapto group, a mercaptoalkyl group and its derivatives, a thiophe, =, a group and its derivatives. is used.

Trifunctional or higher-functional unsaturated compounds include vinyl groups, allyl groups, (
Compounds containing two or more meth)acryloyl groups, etc., such as condensates of (meth)acrylic acid and polyhydric alcohols or polyvalent amines, adducts of (meth)acrylic acid and polyfunctional epoxy compounds, glycidyl (meth) ) Adducts of acrylates and polyhydric alcohols, polyhydric amines, and polycarboxylic acids, condensates of allyl alcohol and polycarboxylic acids, adducts of allyl alcohols and polyfunctional epoxy compounds, allyl halides and polyhydric alcohols and polysiloxanes containing vinyl groups in their side chains. 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 Examples of groups with epoxy groups include epoxy groups, glycidyl groups, and their derivatives, such as polyalkylene chains and polysiloxanes with epoxy groups attached to their terminals. This also includes chains. Examples of compounds that generate Lewis acids when exposed to light include boron tetrafluoride salts such as diazonium, iodonium, and sulfonium, phosphorous hexafluoride salts, and antimony hexafluoride salts.

(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, as the photosensitive component when simply mixed into the photosensitive layer, the following may be used, but the invention is not limited to these.

(1-) Unsaturated monomers or oligomers thereof and photosensitizers.

Examples of the unsaturated monomer include (meth)acrylic acid and its esters, (meth)acrylamides, styrenes, maleic acids and its esters. 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, ethers of polyfunctional carboxylic acids and mercapto alcohols, bor1 siloxanes containing mercaptoalkyl groups in their side chains, and polymers containing thiols in their side chains can be used. .Bifunctional or more-1
The 11-phase iris is a compound containing two or more vinyl groups, allyl groups, (meth)acrylic [:J. Condensate of polyvalent amine and σ), adduct of (meth)acrylic acid and polyfunctional L-poxy compound, glycidyl (meth)acrylic acid-
7. Condensation products of allyl alcohol and polyhydric alcohols, polyhydric alcohols, polyhydric amines, polyhydric carboxylic acids, allyl alcohol and polyhydric carboxylic acids, allyl alcohol and polyfunctional carboxylic acids,
::・Adducts with compounds, condensates of allyl halides and polyhydric alcohols, polysiloxanes containing vinyl groups in their side chains, polymers containing vinyl groups in their side chains, etc. are used.

(3) At least a trifunctional or higher functional epoxy compound and a compound that generates a Lewis acid when exposed to light.A trifunctional or higher functional epoxy compound, an aromatic or aliphatic compound containing fi, N, N-diglycidylamino groups, 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. Examples of compounds that generate Lewis acids when exposed to light include boron tetrafluoride salts such as diazonium, iodonium, and sulfonium, phosphorous hexafluoride salts, and antimony hexafluoride salts.

(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=11''-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; Examples include reaction products with hydroxyl group-containing compounds such as 2,4-dihydroxybenzophenone, 2-hydroxy-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 and-based alcohol.

(7) an aromatic bisazide compound, such as 4,4′-diazidobiphenyl, a cyclized rubber, and a sensitizer;
1-ditropylene etc.

The photosensitive layer of the present invention contains a photosensitive component in an amount of 0.1 to 99.5% by weight, preferably 1 to 90% by weight, based on the total components of the photosensitive layer.

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-~
10 μm is preferable, more preferably 0°3 to 5 μm
It is. In addition, the thickness of the ink repellent layer is 0.5 to 1.0
0Iim, more preferably 1-50 μm.

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

Example 1 1.00 g of methyl methacrylate and 13 g of 2-hydroxyethyl methacrylate were mixed with 50 g of methyl isobutyl ketone.
0 g and polymerized using azobisisobuticonitrile to obtain a polymer 1 having a hydroxyl group in the side chain.

A room temperature curing silicone gum composition with the following composition was placed on an aluminum plate in a grained chamber with a thickness of 0.24 mm. <- It was coated using a coater and cured by heating at 100° C. for 2 minutes to provide a silicone rubber layer.

Dual-terminated silanol polysiloxane PS347°5 (manufactured by Chisso Corporation) 100 parts by weight Ethyltriacetoxysilane 1-2 parts by weight Toluene
The thickness of the silicone rubber layer obtained was 325 parts by weight.
．． It was 511m. On this silicone rubber layer, a solution of a photocurable composition having the following composition was applied using a bar coater and dried at 60°C for 2 minutes to provide a photosensitive layer.

Polymer 1 70 parts by weight Phenyldiacetoxyboron 20 parts by weight "Aronix" M-3
10 (manufactured by Toagosei Chemical Industry Co., Ltd.: 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 Methyl isobutyl ketone 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 problems, and can be easily used in planographic printing without the need for dampening water. We were able to obtain the original printing plate.

For the obtained lithographic printing original plate that does not require dampening water, the adhesive strength between the photosensitive layer and the silicone layer was evaluated by a peel test using the adhesiveness of cellophane tape. As a result, the adhesion between the photosensitive layer and the silicone layer was strong, and the photosensitive layer was not peeled off by cellophane tape. A negative film was vacuum-adhered to this lithographic printing original plate that did not require dampening water, exposed to light using a high-pressure mercury lamp, and then developed with acetone. The photosensitive layer in the exposed area became insoluble in toluene and was firmly adhered to the silicone rubber layer. It was found that the unexposed areas of the photosensitive layer could be dissolved and removed without the need for physical force and could be easily developed. Through this development, a printing plate faithful to the image of the negative film could be obtained.

Attach this printing plate to the Hamada Star offset printing machine,
When offset printing was performed without using dampening water, prints that faithfully reproduced the negative film image were obtained, and 5
It was found that it was possible to print more than 1,000 sheets.

Comparative Example 1 A process was carried out in exactly the same manner as in Example 1, except that polymethyl methacrylate, which is a polymer without hydroxyl groups in the side chain, was used instead of Polymer 1, and an acetoxyboron compound was not added to the photosensitive layer. An original plate for lithographic printing that does not require dampening water was obtained.

For the obtained lithographic printing original plate that does not require dampening water, the adhesive strength between the photosensitive layer and the silicone layer was evaluated by a peel test using the adhesiveness of cellophane tape. As a result, the adhesion between the photosensitive layer and the silicone layer was weak, and the photosensitive layer was easily peeled off with cellophane tape. A negative film was vacuum-adhered to this lithographic printing original plate that did not require dampening water, exposed to light using a high-pressure mercury lamp, and then developed with acetone. It was found that the exposed areas of the photosensitive layer became insoluble in toluene, and the unexposed areas of the photosensitive layer could be dissolved and removed without the need for physical force, allowing for development.

Although it was possible to obtain a printing plate that reproduced the image of the negative film through this development, a portion of the photosensitive layer fell off during the exposure and development operations, and the plate surface was scratched. When this printing plate was attached to a Hamada Star offset printing machine and offset printing was performed without using dampening water, a print that reproduced the image of the negative film was obtained, but the scratches on the plate surface described above appeared on the print. . Further, after printing about 200 sheets, the photosensitive layer further began to fall off, and normal printing could no longer be performed.

Example 2 Both-terminated silanol polydimethylsiloxane (PS340
(manufactured by Chisso Corporation) and 36 g of 3-methacryloxypropyldimethylchlorosilane were reacted in toluene under dry nitrogen in the presence of triethylamine to obtain methacrylate monomer 1 containing silanol groups. Furthermore, 75 g of this monomer and 4.0 g of vinyldimethylchlorosilane were added. Og in the presence of triethylamine under dry nitrogen,
The reaction was carried out in toluene to obtain methacrylate monomer 2 containing a vinyl group.

25g methyl methacrylate, 20g monomer 1.2
0 g of Monomer 2 was dissolved in 300 g of toluene and copolymerized using azobisisobutyronitrile to obtain Polymer 2 having silanol groups as hydroxyl groups. In addition, 100 g of hexamethylcyclotrioloxane, 1 liter of lis(3-mercaptopropyl)trimethylcyclotrisiloxane
．． 8g, both-terminated silanol polysiloxane oligomer 1
0 g was polymerized using an alkali catalyst to obtain polysiloxane 1 containing mercapto groups in the side chains.

On a grained aluminum plate with a thickness of 0.24 rrim, a room temperature curing silicone gum composition having the following composition was applied using a bar coater, and heated and cured at 100°C for 2 minutes.
A silicone rubber layer was provided.

Polysiloxane 1 100 parts by weight Vinyltriacetoxysilane 12 parts by weight Toluene
The thickness of the silicone rubber layer obtained in an amount of 325 parts by weight was 5 μm. A photosensitive layer solution having the following composition was applied onto this silicone rubber layer using a bar coater. This is 60
It was dried at .degree. C. for 2 minutes, a photosensitive layer was provided, and a lithographic printing original plate requiring no dampening water was obtained.

Polymer 2 10.0 parts by weight Ethoxydiacetoxyboron 20 parts by weight Pentaerythritol tetrakis (thioglycolate) (polyfunctional mercapto compound; manufactured by Yodo Kagaku Co., Ltd.) 10 parts by weight "Florado" FC-431 (manufactured by 3M Company) 5 parts by weight "Irgacure" 651 (manufactured by Ciba Geigy) 5 parts by weight Toluene 400 parts by weight The thickness of the photosensitive layer obtained was 1.0 μm.

For the obtained lithographic printing original plate that does not require dampening water, the adhesive strength between the photosensitive layer and the silicone layer was evaluated by a peel test using the adhesiveness of cellophane tape. As a result, the adhesion between the photosensitive layer and the silicone layer was strong, and the photosensitive layer was not peeled off by cellophane tape. A negative film was vacuum-adhered to this lithographic printing original plate that did not require dampening water, exposed to light using a high-pressure mercury lamp, and then developed with acetone. The photosensitive layer in the exposed area became insoluble in toluene and was firmly adhered to the silicone rubber layer. It was found that the unexposed areas of the photosensitive layer could be dissolved and removed without the need for physical force and could be easily developed. Through this development, a printing plate faithful to the image of the negative film could be obtained.

Attach this printing plate to the Hamada Star offset printing machine,
When offset printing was performed without using dampening water, printed matter that faithfully reproduced the negative film image was obtained.
It was found that it was possible to print more than 0,000 sheets.

Example 3 A room temperature curable silicone gum composition having the following composition was applied onto a grained aluminum plate with a thickness of 0.24rnrn using a bar coater, and heated and cured at 100°C for 2 minutes to form a silicone rubber. Layers were provided.

Dual-terminated silanol polysiloxane PS347゜5 (manufactured by Chisso Corporation) -00 parts by weight Vinyl tris(methyl ethyl ketoxime) silane
8 parts by weight toluene
The thickness of the silicone rubber layer obtained was 325 parts by weight.
It was m. A solution of a photocurable composition having the following composition containing a phenolic hydroxyl group was applied onto this silicone rubber layer using a bar coater and dried at 60'C for 2 minutes to provide a photosensitive layer.

Poly-p-hydroxystyrene 70 parts by weight Ethylene acetoxyboron 1.0 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 (manufactured by Ciba Geigy) 5 parts by weight Methyl isobutyl 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, making it possible to easily obtain a lithographic printing original plate that did not require dampening water.

For the obtained lithographic printing original plate that does not require dampening water, the adhesive strength between the photosensitive layer and the silicone layer was evaluated by a peel test using the adhesiveness of cellophane tape. As a result, the adhesion between the photosensitive layer and the silicone layer was strong, and the photosensitive layer was not peeled off by cellophane tape. A negative film was vacuum-adhered to this lithographic printing original plate that did not require dampening water, exposed to light using a high-pressure mercury lamp, and then developed with acetone. The photosensitive layer in the exposed area became insoluble in toluene and was firmly adhered to the silicone rubber layer. It was found that the unexposed areas of the photosensitive layer could be dissolved and removed without the need for physical force and could be easily developed. Through this development, a printing plate faithful to the image of the negative film could be obtained.

Attach this printing plate to the Hamada Star offset printing machine,
When offset printing was performed without using dampening water, prints that faithfully reproduced the negative film image were obtained, and 5
It was found that it was possible to print more than 500 sheets.

[Effects of the Invention] Since the present invention is configured as described above, it is possible to obtain a lithographic printing original plate that does not require dampening water and is easy to develop, has strong adhesive strength between the silicone rubber layer and the photosensitive layer, and has improved printing durability. was completed.

Claims (1)

[Claims] 1. In a lithographic printing original plate that does not require dampening water and is formed by providing a silicone rubber layer and a photosensitive layer in this order on a substrate, the photosensitive layer contains a polymer containing a hydroxyl group in its side chain and an alkanoyloxyboron compound as a component. An original plate for lithographic printing that does not require dampening water.