JP2000122271A - Image forming material and printing plate making method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an image forming material which does not change the image area without rigorously controlling dampening water, which does not require a processing using a developer to form an image, and which stably gives enough printing quality without causing lots of paper loss, by forming a sea-island hydrophilic layer which changes to be oleophilic by radiation or heat, on a supporting body. SOLUTION: A sea-island hydrophilic layer is formed on a supporting body. This hydrophilic layer becomes the outermost layer after an image is formed, and it has a sea-island structure consisting of a continuous phase and a discontinuous phase and it changes into oleophilic by radiation or heat. The area except for the region of the sea-island hydrophilic layer which changed into oleophilic can be removed. The discontinuous phase consists of an org. high mol.wt. polymer and the org. polymer is obtd. by polymn. of compds. having ethylenic unsatd. bonds. By using the image forming material which does not require a process with a developer for formation of an image to produce a lithographic printing plate, printed products with stable quality from the initial stage of printing can be obtd. in an enough amt.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming material capable of forming an image comprising a hydrophilic surface and a lipophilic surface by changing a hydrophilic surface to lipophilic by radiation or heat, and lithographic printing using the same. More specifically, the present invention relates to an image forming material that does not require a treatment with a developer for forming the image, and a method for manufacturing a lithographic printing plate using the same.

[0002]

2. Description of the Related Art The following techniques are known as image forming materials which do not require treatment with a developing solution for producing a lithographic printing plate.

JP-A-60-132760 discloses that an image portion is formed by hydrophilizing the surface of a plate material made of a lipophilic polymer, and a hydrophilic sensitive group on the surface of the image portion is selectively formed by a laser beam. A method for manufacturing a lithographic printing plate for removing an image portion on the surface is disclosed. However, in this technique, since the non-image portion and the image portion exist on the same plane, the boundary between the non-image portion and the image portion fluctuates unless the dampening solution is strictly managed, and the image area changes. There was a problem.

Japanese Patent Application Laid-Open No. 6-502931 discloses a polymer hydrophilic binder and a photopolymerizable, photocrosslinkable or phototransferable compound which promotes insolubilization or curing in an exposed area on a printing plate substrate. Lithographic printing comprising a photosensitive hydrophilic layer containing a polymer, and a photosensitive hydrophobic layer containing a polymer hydrophobic binder and a photopolymerizable, photocrosslinkable or phototransferable compound that promotes insolubilization or curing in the exposed area. A plate is disclosed. However, this technology can use a roughened aluminum plate as used in a conventional printing plate as the non-image portion, so that the print quality is greatly reduced due to wear of the non-image portion. However, there is a problem in that the number of prints from the start of printing until a stable print quality is obtained is large, resulting in a large waste of printing paper called broke. Further, as a mode that does not generate much waste paper, a method of removing a part of a hydrophobic layer or a hydrophilic layer by peeling a protective sheet is disclosed, but there is a problem that a waste material of a protective sheet is generated. Not only that, the printing plate is liable to be broken at the time of peeling, and may not be used as a printing plate.

[0005]

SUMMARY OF THE INVENTION The present invention is to solve the above-mentioned problems of the prior art. First, a lithographic printing plate in which the image area does not change even if fountain solution is not strictly controlled. Secondly, it is possible to provide an image forming material which does not require treatment with a developing solution, and secondly, it is possible to obtain a sufficient print quality without generating a lot of waste paper without providing a protective sheet as in the above-mentioned conventional technology. The object of the present invention is to provide an image forming material which does not need to be treated with a developer to obtain a lithographic printing plate capable of stably obtaining lithographic printing plates.

[0006]

The above object of the present invention is achieved by the following constitution.

(1) A hydrophilic layer serving as an outermost layer at least after image formation, having a sea-island structure composed of a continuous phase and a discontinuous phase, and having a sea-island structure that changes to lipophilic by radiation or heat. An image forming material, which is provided on a support.

(2) The image forming material as described in (1) above, wherein portions other than the lipophilic portion of the sea-island structure hydrophilic layer can be removed.

(3) The image forming material as described in (1) or (2) above, wherein at least one hydrophilic layer is provided between the sea-island structure hydrophilic layer and the support.

(4) The image forming material as described in (1), (2) or (3) above, wherein the discontinuous phase is an organic high molecular polymer.

(5) The image forming material as described in (4) above, wherein the organic polymer is an organic polymer obtained by polymerization of a compound having an ethylenically unsaturated bond.

(6) The image forming material as described in any one of (1) to (5) above, wherein the sea-island structure hydrophilic layer is a photosensitive layer.

(7) The image forming material as described in any one of (3) to (5) above, wherein the sea-island structure hydrophilic layer and the hydrophilic layer are photosensitive layers.

(8) A hydrophilic layer serving as an outermost layer at least after image formation, having a sea-island structure composed of a continuous phase and a discontinuous phase, and having a sea-island structure that changes to lipophilic by radiation or heat. A method for producing a printing plate, comprising using an image forming material provided on a support.

(9) A support comprising a hydrophilic layer serving as an outermost layer at least after image formation, having a sea-island structure comprising a continuous phase and a discontinuous phase, and having a sea-island structure which changes to lipophilic by exposure. A method for producing a printing plate, comprising: preparing a printing plate using the above-described image forming material; and then subjecting the sea-island structure hydrophilic layer to lipophilic treatment.

(10) The method of making a printing plate as described in (9) above, wherein the lipophilic treatment is heating and / or pressurizing.

The present invention solves the above-mentioned problems of the prior art by the image forming material having the above-mentioned structure or the method of preparing a lithographic printing plate using the image forming material according to the present invention. It is possible to obtain a sufficient number of prints of stable quality from the initial stage of printing by using a lithographic printing plate prepared using an image forming material that does not require the above-described processing. Also, by making the hydrophilic layer a sea-island structure, the change from hydrophilic to lipophilic can be made not as a property change only at the surface of the hydrophilic layer but as a property change including the strength change of the entire layer. became. As a result, the amount of change in the hydrophilicity / lipophilicity change is increased, and a clearer image can be obtained quickly and easily. Further, even when the surface was worn by printing, the performance as a printing plate did not significantly decrease, so that the number of printable sheets increased.

Hereinafter, the present invention will be described in detail.

In the image forming material of the present invention, a hydrophilic layer which becomes an outermost layer after image formation, has a sea-island structure composed of a continuous phase and a discontinuous phase, and changes to lipophilic by radiation or heat. The sea-island structure in the hydrophilic layer means a phase-separated structure represented by the first type of closed structure described in Chapter V, Section 5, Introduction to Polymer Latex (Souichi Muroi). Represents a phase dispersed in the form of particles in the layer, and a continuous phase means a phase existing outside a discontinuous phase.

In the present invention, the hydrophilic layer refers to a layer having a surface having a contact angle with water of 30 ° or less and a contact angle with diiodomethane of 30 ° or more. The contact angle of water on the surface of
° or more and a contact angle with diiodomethane of 50 ° or less.

For the continuous phase, a hydrophilic compound soluble in a coating solvent is used. Specifically, gelatin, polyvinyl alcohol, polyvinylpyrrolidone, polyalkylene oxide, carboxymethylcellulose, hydroxymethylpropylcellulose and various derivatives of the above compounds, poly (meth) acrylic acid, poly (meth) acrylic acid hydroxyester, and the like Copolymer, polyhydric alcohols such as glycerin and erythritol, hydrophilic inorganic compounds such as sodium silicate, and photosensitive and / or
Or a combination of a hydrophilic lipophilic polymer having heat sensitivity and a hydrophilic polymer which forms an association by radiation or heat to lipophilize, among others, a function of lipophilicity by radiation or heat. It is preferable to use a combination of a lipophilic polymer which has been made hydrophilic and a hydrophilic polymer which forms an aggregate and is made lipophilic.

When a hydrophilic compound which does not change to lipophilic by radiation or heat is used for the continuous phase, the lipophilicity of the hydrophilic layer is
For example, surface exposure of a discontinuous phase due to volatilization of a hydrophilic continuous phase,
This is achieved by a phase transition of the sea-island structure (continuous phase → discontinuous phase, discontinuous phase → continuous layer), layer surface coating by melting and leaching of the lipophilic compound in the discontinuous phase. That is, an image is formed mainly by a change in the layer structure or a change in the physical or shape of the layer constituent material. This change is mainly performed by using heat at the time of image recording, and when imparting photosensitivity, it is preferable to use a photothermal conversion agent that absorbs recording light.

When a continuous phase that changes to lipophilic by radiation or heat, which is a preferred embodiment of the present invention, is used, the lipophilic polymer that has been hydrophilized is removed by removing the hydrophilic groups generated by the hydrophilization treatment. In the continuous phase containing the resole resin and polyethylene oxide, the hydrophilicity of the compound is lost due to the association, and the compound becomes lipophilic to form an image area of a lithographic printing plate. The photosensitivity at this time is imparted by a photothermal conversion agent that absorbs recording light, as described above.

When a continuous phase which changes lipophilicity by radiation or heat is used, it is possible to form an image without using an image forming action due to a change in the layer structure or a change in the physical or shape of the layer constituting material. It is preferable to adopt a configuration utilizing these image forming actions.

The hydrophilic lipophilic polymer having photosensitivity can be obtained, for example, by subjecting the following lipophilic polymer to a hydrophilic treatment. For example, aromatic polymers such as polystyrene and polyvinyl toluene, polyolefins such as polyethylene, polypropylene, and polybutene-1, diene polymers such as polybutadiene and polyisoprene, and poly (meth) acrylates such as polyolefin, polymethyl (meth) acrylate, and polyethyl (meth) acrylate ) Acrylic esters, polyvinyl acetates, polyvinyl esters such as polyvinyl butyrate, polyvinylidene halides such as polyvinylidene chloride, halogenated polyolefins such as chlorinated polyethylene, polyesters such as polyethylene terephthalate, and blends of these polymers and related compounds Copolymers with monomers, further, cellulose acetate such as triacetyl cellulose and polyamide such as 12 nylon are exemplified. As a preferable one, in consideration of sulfonation, which is a preferred method for hydrophilization described later, a polymer capable of being sulfonated, that is, having a hydrogen atom that can be substituted and bonded to a carbon atom, and the main chain is cleaved during the sulfonation reaction. Those that are difficult to perform are preferred. Examples of the method for hydrophilizing the lipophilic polymer include polyacrylonitrile, a method of hydrolyzing the surface of an acetylated cellulose-based polymer with an aqueous solution of caustic soda, a method of oxidizing the surface of a hydrocarbon-based polymer with dichromic acid, nitric acid, and the like, Hydrophilization can be performed by a method of sulfonating with fuming sulfuric acid, sulfuric anhydride, or the like, or a method of grafting a monomer having a hydrophilic group. As the hydrophilic group generated by hydrophilization, generally, a hydroxyl group, a carboxyl group, an amino group, an amide group, a sulfone group, a phosphoric acid group may be mentioned, but when the hydrophilic group is a sulfone group, a relatively low energy amount is used. This is preferred in that lipophilicity is possible. As the sulfonation method, a method generally used industrially as a sulfonation method in which sulfonation is performed in fuming sulfuric acid, concentrated sulfuric acid, or sulfuric anhydride (gas) can be used. The photosensitized hydrophilic lipophilic polymer is one that becomes a plate surface of a lithographic printing plate by selectively removing hydrophilic functional groups on the surface by radiation or heat to form a lipophilic image area on the surface. is there. Also,
Other configurations that change to lipophilicity include those described in Tokiko 42
No. 14,328, a configuration that causes a change in lipophilicity depending on the association form of a resole resin and polyethylene oxide can be used for the continuous phase of the hydrophilic layer. The above configuration utilizes the property that the resole resin and polyethylene oxide form an association by heat and change from hydrophilic to lipophilic, and the coexistence of a photosensitive halogenated photosensitivity such as iodoform enhances the photosensitivity. It is also possible to provide. In the continuous phase of the sea-island structure hydrophilic layer of the present invention, a plasticizer other than the above-described polymer, a plasticizer for the purpose of adjusting physical properties, physical properties, as long as the effect of the hydrophilicity and the lipophilic treatment is not impaired. Various additives such as an agent may be used. Preferably, the continuous phase of the present invention is uncrosslinked or only slightly crosslinked.

The discontinuous phase of the sea-island structure hydrophilic layer of the present invention may be a metal or an inorganic compound such as a metal oxide or a metal nitride. However, an organic high molecular polymer is preferable. It is preferable to use organic compounds, especially fine particles of a hydrophobic polymer. Although there is no specific upper limit for the softening temperature of the hydrophobic polymer fine particles, the softening temperature is preferably lower than the decomposition temperature of the polymer fine particles.

As a specific example of the polymer constituting the fine particles of the polymer preferably used in the present invention, a polymer obtained by polymerization of a compound having an ethylenically unsaturated bond is preferable. For example, polyethylene, polypropylene, polyolefins such as ethylene-butene copolymer,
Synthetic rubbers such as diene (co) polymers such as polybutadiene, polyisoprene, ethylene-butadiene copolymer, styrene-butadiene copolymer, methyl methacrylate-butadiene copolymer, acrylonitrile-butadiene copolymer, and polymethyl Methacrylate, methyl methacrylate- (2-ethylhexyl acrylate) copolymer, methyl methacrylate-methacrylic acid copolymer, methyl acrylate- (N-methylol acrylamide)
Copolymers, (meth) acrylates such as polyacrylonitrile, (meth) acrylic acid (co) polymers, polyvinyl acetate, vinyl acetate-vinyl propionate copolymer,
Examples thereof include vinyl ester (co) polymers such as vinyl acetate-ethylene copolymers, vinyl acetate- (2-ethylhexyl acrylate) copolymers, polyvinyl chloride, polyvinylidene chloride, polystyrene and the like, and copolymers thereof. , Of these, (meth) acrylates,
(Meth) acrylic acid (co) polymer, vinyl ester (co) polymer, polystyrene, and synthetic rubbers are preferably used. The weight average molecular weight Mw of the organic high molecular polymer is preferably in the range of 5,000 to 1,000,000. When the organic polymer contains a functional group having an acid value, the ionomer resin may have a structure in which a part or all of the functional groups are cross-linked via polyvalent metal ions and integrated.

The fine particles of the organic high molecular polymer are obtained by an emulsion polymerization method,
It may be composed of a polymer polymerized by any conventionally known method such as a suspension polymerization method, a solution polymerization method, and a gas phase polymerization method. As a method of forming fine particles of a polymer polymerized by a solution polymerization method or a gas phase polymerization method, a method of spraying a solution in an organic solvent of the high molecular polymer in an inert gas, drying and forming fine particles, A method of dissolving a high-molecular polymer in an organic solvent immiscible with water, dispersing the solution in water or an aqueous medium, and evaporating the organic solvent to form fine particles can be used. In any method, a dispersant or a stabilizer may be used as a dispersant or a stabilizer during polymerization or micronization, if necessary, as a surfactant such as sodium lauryl sulfate, sodium dodecylbenzenesulfonate, or polyethylene glycol; May be used.

The fine particles of the organic high molecular polymer are preferably used in the form of a dispersion dispersed in a dispersion medium, and more preferably an aqueous dispersion. The polymer particles preferably have a particle diameter of 0.005 to 2 μm, and the amount of the organic polymer particles contained in the layer containing the organic polymer particles is preferably Is at least 30% by weight, more preferably at least 45% by weight, most preferably at least 60% by weight.

The support used in the present invention is not particularly limited, but it is preferable to use a hydrophilic support having a hydrophilic layer or a hydrophilic surface. The hydrophilic support may be paper, plastic, metal, etc., but is not limited thereto. Coated paper, plastic sheet whose surface has been made hydrophilic by a treatment such as corona discharge, or a surface whose surface is grained or anodized. A treated aluminum plate or the like can be used. When a hydrophilic layer is provided on the support to form a hydrophilic support, an intermediate layer such as an adhesive layer may be provided between the support and the hydrophilic layer.

In the hydrophilic layer which is not the outermost layer, usable materials include gelatin, polyvinyl alcohol, polyvinylpyrrolidone, polyalkylene oxide, carboxymethylcellulose, hydroxymethylpropylcellulose and various derivatives of the above compounds, poly (meth)
Acrylic acid, poly (meth) acrylic acid hydroxyester, copolymers thereof and the like can be mentioned.

The hydrophilic layer is preferably photosensitive. The photosensitivity of the hydrophilic layer is imparted by using a known composition of a known photopolymerization type or photocrosslinking type. Specifically, for example, polymerizable compounds such as dipentaerythritol hexaacrylate, polyethylene glycol diacrylate, glycerol epichlorohydrin-modified triacrylate, tetramethylolpropane triacrylate, and 2,4-dimethylthioxanthone, 2,2-dimethoxy-2- Phenylacetophenone, Kayacure QTX
Photosensitivity can be imparted by using a photopolymerization initiator such as (manufactured by Nippon Kayaku Co., Ltd.) in an appropriate combination of the hydrophilicity of the hydrophilic layer and using it to such an extent that the hydrophilicity is not lost. By imparting photosensitivity to the hydrophilic layer and performing exposure with actinic light exhibiting photosensitivity during and / or after image recording, a stronger image can be obtained and the number of printable sheets can be increased.

The sea-island structure hydrophilic layer of the present invention contains a compound which is heat-sensitive and can convert light into heat when forming an image with light (hereinafter referred to as "photothermal conversion compound"). Preferably. In the present invention, the photothermal conversion compound is preferably infrared-absorbing, but if the absorption of the compound is within the wavelength range of the light source used for image exposure, the absorption wavelength may be in another wavelength range. . Particularly useful photothermal conversion compounds are, for example, dyes, especially infrared dyes, carbon black, metal carbides, borides, nitrides,
And carbonitride. As the photothermal conversion compound, a dispersion of a conductive polymer, for example, a dispersion of a conductive polymer based on polypyrrole or polyaniline can also be used. The light-to-heat conversion compound is most preferably added to the sea-island structure hydrophilic layer, but it is also possible to adopt a mode in which part or all of the light-to-heat conversion compound is contained in the layer adjacent to the sea-island structure hydrophilic layer.

The image forming material of the present invention can be used for image formation by direct heating using a thermal head or the like, but can be preferably used as an image forming material for forming an image by irradiation with actinic rays. When an image is formed by irradiation with actinic rays, a photochemical reaction caused by actinic rays may be used, or a thermal reaction caused by a photothermal conversion compound may be used.

When an image is formed by converting light into heat, the imagewise irradiation of light is preferably performed by scanning exposure with a laser.
More preferably, a laser operating in the wavelength region of 00 nm is used. Most preferred are laser diodes that emit near infrared.

Since the sea-island structure hydrophilic layer to which radiation or heat is imparted imagewise changes to lipophilic like an image, and the other portions are hydrophilic, it can be used as a lithographic printing plate as it is. In addition, the sea-island structure hydrophilic layer in the non-image area can be removed by, for example, exposing the image-exposed image forming material to running water to use it as a printing plate.

The printing plate is preferably subjected to a lipophilic treatment for increasing the lipophilicity of the sea-island structure hydrophilic layer. Heat and / or pressure can be used as the lipophilic treatment. As the heating means, an infrared heater, hot air, a heating roller, or the like can be used.
The range is preferably from 1 to 180 seconds at 0 to 300 ° C, more preferably from 1 to 120 seconds at 70 to 200 ° C. Examples of the pressing means include applying a pressure using a roller or a press plate, and the pressing conditions are preferably 0.1 to 50 kg, more preferably 1 to ²⁰ kg per 1 cm ² .

[0038]

Example 1 A latex polymer having the following structure was synthesized by emulsion polymerization, dried and dried to obtain fine particles of an organic polymer having an average particle diameter of 0.3 μm.
1 was obtained.

[0039]

Embedded image

Subsequently, a hydrophilic layer composition having the following composition was placed on an aluminum plate having a thickness of about 9.24 mm which had been electrochemically roughened, anodized, and hydrophilized with polyvinylphosphonic acid. Water: ethyl acetate = 92.5:
A coating solution obtained by dissolving a solid content in a mixed solvent of 3.5 (volume ratio) so as to have a solid content of 4% by weight has a dried film thickness of 0.35 μm.
And dried to obtain a hydrophilic layer.

Hydrophilic layer composition Polyethylene glycol wax (molecular weight = 17,000) (Carbowax 20M; manufactured by Union Carbide) 49.4 parts by weight 2,2-dimethoxy-2-phenylacetophenone (Irgacure 651; manufactured by Ciba Geigy) 4.5 parts by weight tetrakis {methylene (3,5-di-tert-2-butyl-4-hydroxyhydrocinnamate)} methane (Irganox 1010; Ciba-Geigy) 0.5 part by weight trimethylolpropane triacrylate (Saltomer 351; manufactured by Sartomer) 45.5 parts by weight Octylphenoxypolyethoxyethanol (Triton X-100; manufactured by Rohm & Haas, 25% aqueous solution) 0.1 part by weight On this hydrophilic layer, a photosensitive sea island is added. Thickness after drying the coating liquid for structural hydrophilic layer Coated to a thickness of 0.7 μm, dried, put in anhydrous sulfuric acid gas, and exposed at 40 to 50 ° C. for about 15 minutes, so that the contact angle with water is 3 ° and the contact angle with diiodomethane is 50 °. The image forming material of the present invention was obtained as a hydrophilic layer having a sea-island structure.

Photosensitive coating solution for sea-island structure hydrophilic layer Organic high molecular polymer fine particles-1 (as described above) 57.0 parts by weight Dipentaerythritol hexaacrylate (DPHA; manufactured by Shin-Nakamura Chemical Co., Ltd.) 5.5 parts by weight glycerol Modified trimethacrylate (Denacol DA-314; manufactured by Nagase Kasei Co., Ltd.) 9.0 parts by weight Mole ratio of methyl methacrylate / hydroxyethyl methacrylate / methacrylic acid / hydroxyphenyl methacrylate / 4-hydroxybutyl acrylate 30/25/20/15/10 14.5 parts by weight 2,2-dimethoxy-2-phenylacetophenone (Irgacure 651; manufactured by Ciba-Geigy) 3.0 parts by weight Tetrakis methylene (3,5-di-tert-2-butyl-4-) Hydroxyhydrocinnamate)｝ methane (a Ganox 1010; Ciba-Geigy) 1.0 part by weight Carbon black (MA-100; manufactured by Mitsubishi Chemical Corporation) 10.0 parts by weight Acetone 450 parts by weight Pure water 450 450 parts by weight This image forming material is attached to a rotating roll. Nd ・ YA
Image exposure was performed with a G laser. The contact angle of the exposed part to water and the contact angle to diiodomethane were 53 °,
28 °. The printing plate thus obtained was mounted on an offset printing machine without being treated with chemicals or the like, and printing was performed. From the 30th printing start, a printed material with good reproduction of halftone dots was obtained. About 100,000 copies could be printed with little adjustment of the amount of dampening solution.

Example 2 A net negative mask was adhered to the image forming material obtained in Example 1,
Image exposure was performed with a UV exposure machine. When the obtained printing plate was exposed to running water, the unexposed portion of the sea-island structure hydrophilic layer was removed. Thereafter, the surface of the image area was made lipophilic by performing a heat treatment at 200 ° C. for 2 minutes. The contact angles of water and diiodomethane in the image area after the lipophilic treatment were 50 ° and 25 °, respectively. When this printing plate was attached to an offset printing machine and printing was performed, a printed material in which halftone dots were reproduced well from the 15th printing start was obtained. 100,000 copies could be printed.

COMPARATIVE EXAMPLE 1 A polyethylene film (thickness: about 200 μm) was put in anhydrous sulfuric acid gas and exposed at 40 to 50 ° C. for about 15 minutes. The contact angle with water was 5 °, and the contact angle with diiodomethane was 5 °.
A 0 ° hydrophilic film was obtained. This film is attached to a rotating roll and image-exposed with a Nd / YAG laser.
When printing was carried out by attaching to an offset printing machine without treatment with chemicals, etc., it was possible to obtain printed matter in which halftone dots were reproduced well from the 30th printing start, but to maintain the quality of the printed matter Adjustment of the dampening water amount was required frequently during printing, and when about 20,000 copies had been printed, the non-image area was stained and could not be used as a printing plate.

Comparative Example 2 A thickness of about 0.24 m, which was electrochemically roughened, anodized, and hydrophilized with polyvinylphosphonic acid
A hydrophilic layer composition having the following composition was dissolved in a mixed solvent of water: ethyl acetate = 92.5: 3.5 (volume ratio) so that the solid content was 4% on an aluminum plate of m. The liquid was applied and dried so that the film thickness after drying was 0.35 μm to obtain a hydrophilic layer.

Hydrophilic layer composition Polyethylene glycol wax (molecular weight = 17,000) (Carbowax 20M; manufactured by Union Carbide) 49.4 parts by weight 2,2-dimethoxy-2-phenylacetophenone (Irgacure 651; manufactured by Ciba Geigy) 4.5 parts by weight tetrakis {methylene (3,5-di-tert-2-butyl-4-hydroxyhydrocinnamate)} methane (Irganox 1010; Ciba-Geigy) 0.5 part by weight trimethylolpropane triacrylate (Saltomer 351; manufactured by Sartomer Co.) 45.5 parts by weight Octylphenoxypolyethoxyethanol (Triton X-100; manufactured by Rohm & Haas Co., Ltd., 25% aqueous solution) 0.1 part by weight A parent having the following composition on this hydrophilic layer The oily layer has a solid content of 8.4% Dissolved so that the film thickness after drying to obtain an image forming material (for comparison) was applied and dried so that the 0.7 [mu] m.

Lipophilic layer composition Ethoxylated trimethylolpropane triacrylate (Saltomer 454; manufactured by Sartomer) 22.0 parts by weight Ethoxylated trimethylolpropane triacrylate (Henkel 4155; manufactured by Henkel) 22.0 parts by weight High molecular weight 36.5 parts by weight of polyethyl methacrylate (Elvasite 2042; manufactured by EI DuPont Domnur) 12.0 parts by weight of low molecular weight polyethyl methacrylate (Elbasite 2043; manufactured by EI Dupont Domneule) 2,2-dimethoxy-2-phenylacetophenone (Irgacure 651; manufactured by Ciba-Geigy) 6.5 parts by weight tetrakis {methylene (3,5-di-tert-2-butyl-4-hydroxyhydrocinnamate)} methane (Irganox 1010; Contact angle 50 ° to water Geigy) 1.0 part by weight of the obtained image forming material, the contact angle to diiodomethane was 25 °.

A net negative mask was brought into close contact with this image forming material, and image exposure was performed with a UV exposure machine. When the obtained printing plate was attached to an offset printing machine without being treated with chemicals and the like, and printing was performed, it was possible to print about 100,000 copies without almost adjusting the dampening solution amount during printing. It is necessary to print 700 sheets from the start of printing until a printed matter in which halftone dots are well reproduced is obtained.
It took a lot of broke and time.

[0049]

According to the present invention, it is possible to obtain a lithographic printing plate in which the image area does not change even if the dampening solution is not strictly controlled, and it does not generate much waste paper (radiation (heat)). A lithographic printing plate capable of stably obtaining sufficient printing quality can be obtained (without a protective sheet provided with a protective sheet on the conductive layer and peeling off the protective sheet together with the lower layer after imagewise radiation (heating)). An image forming material that does not require treatment with a developer is provided.

Claims (10)

[Claims] 1. A hydrophilic layer serving as an outermost layer at least after image formation, having a sea-island structure comprising a continuous phase and a discontinuous phase, and supporting a sea-island structure hydrophilic layer which changes to lipophilic by radiation or heat. An image forming material, which is provided on a body. 2. The image forming material according to claim 1, wherein portions other than the lipophilic portion of the sea-island structure hydrophilic layer can be removed. 3. The image forming material according to claim 1, further comprising at least one hydrophilic layer between the sea-island structure hydrophilic layer and the support. 4. The image forming material according to claim 1, wherein the discontinuous phase is an organic high molecular polymer. 5. The image forming material according to claim 4, wherein the organic polymer is an organic polymer obtained by polymerizing a compound having an ethylenically unsaturated bond. 6. The image forming material according to claim 1, wherein the sea-island structure hydrophilic layer is a photosensitive layer. 7. The image forming material according to claim 3, wherein the sea-island structure hydrophilic layer and the hydrophilic layer are photosensitive layers. 8. A hydrophilic layer serving as an outermost layer at least after image formation, having a sea-island structure comprising a continuous phase and a discontinuous phase, and supporting a sea-island structure hydrophilic layer which changes to lipophilic by radiation or heat. A method for producing a printing plate, comprising using an image forming material provided on a body. 9. A support having a sea-island structure hydrophilic layer which is at least an outermost layer after image formation and has a sea-island structure comprising a continuous phase and a discontinuous phase, and which changes to lipophilic by exposure. A method for producing a printing plate, comprising: preparing a printing plate using the image forming material according to (1); and performing lipophilic treatment on the sea-island structure hydrophilic layer. 10. The printing plate manufacturing method according to claim 9, wherein the lipophilic treatment is heating and / or pressurizing.