JP2577604B2 - Lithographic printing plate material that does not require dampening water - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a lithographic printing plate material requiring no dampening solution, and more particularly to a stencil making process which is simplified, has excellent dot reproducibility, and reduces developer fatigue. And a lithographic printing plate material which can be measured without a dampening solution.

[Prior Art] A fountain solution-free lithographic printing plate material having a silicone rubber layer on the uppermost layer for forming a non-image area having ink repellency is:
For example, Japanese Patent Publication Nos. 44-23042, 46-16044 and 51-1708
Nos. 1, 54-26923, 55-22781 and the like.

In order to form an image on such a lithographic printing plate material requiring no dampening solution, exposure with actinic light is usually performed through the original image, but in order to faithfully reproduce the original image, the original image is completely adhered to the upper surface of the plate material. Was necessary. For this reason,
In general, a vacuum contact method has been used in which the plate material and the original image are placed between the rubber sheet and the pressure-bonded glass so as to overlap each other, and the space between the rubber sheet and the pressure-bonded glass is evacuated and adhered.

However, it is difficult to achieve sufficient vacuum adhesion,
Various techniques have been proposed to improve these.

For example, Japanese Patent Laid-Open No. 55343/1979 discloses a technique of coating an uneven transparent film on the uppermost silicone rubber layer. JP-A-56-27150 proposes a technique in which the uppermost silicone rubber layer has an uneven surface. Further, Japanese Patent Application Laid-Open No. 6-27547 proposes a technique in which a mat layer which is soluble in a developer is provided on a silicone rubber layer.

[Problems to be Solved by the Invention] However, in JP-A-55-55343, there is a problem in simplification of the plate making process because it is necessary to peel off the uneven transparent film after exposure. No. 27150, there is a problem that the halftone dot reproducibility is inferior.
No. 5, there is a problem that developer fatigue is large.

[Object of the Invention] Accordingly, an object of the present invention is to provide a lithographic printing plate material which improves vacuum adhesion, simplifies the plate making process, reduces developer fatigue, and has good dot reproducibility without dampening solution. Is to do.

[Means for Solving the Problems] The present inventor has conducted intensive studies in order to achieve the above object,
The present invention has been reached.

That is, the fountain solution-free lithographic printing plate material according to the present invention is a fountain solution-free lithographic printing plate material having a photosensitive layer and a silicone rubber layer in this order on a support. Without using an insoluble binder, a developer-insoluble solid particle has a discontinuous mat layer to which heat-sealed solid particles are fixed, and the solid particles are swelled by the developer to form a solid particle silicone rubber layer. Are particles that fall off due to a decrease in the adhesive force of the particles.

[Action] In the present invention, since the silicone rubber layer has a discontinuous mat layer on which solid particles are fixed,
Not only can the vacuum adhesion be improved, but also there is no step of peeling off the concavo-convex transparent film after exposure as in the prior art, so that the plate making process can be simplified and the halftone dot reproducibility does not decrease.

Further, according to the present invention, since solid particles are insoluble in a developer, even if the solid particles are mixed in the developer after the development, they can be easily separated by means such as filtration, thereby reducing the fatigue of the developer. Furthermore, since the present invention is fixed by heat fusion, compared to fixing solid particles to a silicone rubber layer using a conventional developer-soluble or insoluble binder,
Since there is no developer fatigue due to the binder, the developer fatigue can be reduced.

Japanese Patent Application Laid-Open No. 55-12974 discloses a technique for heat-welding solid particles on a photosensitive layer. This technique relates to a plate material requiring a dampening solution, and relates to a silicone rubber layer. The structure is fundamentally different from that of the present invention in which solid particles are heat-welded. For this reason, the action (effect) of removing solid particles after exposure is crucially different. That is, while the conventional method dissolves and removes the solid particles in the developer, the present invention irrespective of the dissolution of the solid particles in the developer, swells the silicone rubber layer with the developer to form solid particles. The solid particles fall off due to a decrease in the mounting force of the silicone rubber layer. Therefore, even if the conventional method proves that the solid particles are effective for improving the vacuum adhesion, the fatigue of the developer cannot be reduced.

[Configuration of the Invention] Hereinafter, the present invention will be described in detail.

The fountain solution-free lithographic printing plate material of the present invention (hereinafter, also referred to as a fountain solution-free plate material or simply a plate material) is, as shown in FIG. It has a layer 2 and a silicone rubber layer 3, and has a discontinuous mat layer on which solid particles are fixed on the silicone rubber layer 3.

As the support, it is preferable that the support can be set in a normal lithographic printing machine and can withstand the load applied during printing.For example, aluminum, zinc, copper, a metal plate such as steel, and chromium, zinc, copper, Examples thereof include metal plates, paper, plastic films and glass plates plated with nickel, aluminum, and iron, plastic films and glass plates, resin-coated paper, paper covered with metal foil such as aluminum, and plastic films subjected to hydrophilic treatment. Of these, an aluminum plate is preferable. When an aluminum plate is used, graining treatment such as graining treatment and anodic oxidation treatment may be performed.

The thickness of the support is preferably from 50 to 400 µm, more preferably from 100 to 300 µm.

A primer layer may be provided on the support, and a resin or a silane coupling agent is preferable for the primer layer. Examples of the resin include a polyester resin, a vinyl chloride-vinyl acetate copolymer, an acrylic resin, and a chloride resin. Examples include vinyl resin, polyamide resin, polyvinyl butyral resin, epoxy resin, acrylate copolymer, vinyl acetate copolymer, phenoxy resin, polyurethane resin, polycarbonate resin, polyacrylonitrile butadiene, and polyvinyl acetate. Among them, epoxy resins are preferred.

As the anchor agent constituting the primer layer, for example, a silane coupling agent or a silicone primer used in the silicone rubber layer can be used, and an organic titanate is also effective.

The structure of the photosensitive layer is not particularly limited, and various photosensitive materials are used. Hereinafter, typical ones will be described.

First, a quinonediazide-type positive photosensitive material such as a conventionally known o-naphthoquinonediazide compound may be used. Suitable o-naphthoquinonediazide compounds include
There are esters of naphthoquinone- (1,2) -diazide- (2) -sulfonic acid chloride with phenol or cresol formaldehyde resins described in U.S. Pat. No. 3,048,120. Other useful o-naphthoquinonediazide compounds include, for example, U.S. Pat.
Pyrogallol-acetone resin and o-
Esters of naphthoquinonediazidesulfonic acid chloride, JP-A-55-76343, JP-A-56-1044 and JP-A-56-1045.
Polyhydroxyphenyl resin and o-
Esters of naphthoquinonediazidesulfonic acid chloride, homopolymers of p-hydroxystyrene or copolymers thereof with other copolymerizable monomers as described in JP-A-50-113305 may be added to o-naphthoquinonediazide sulfone. An acid chloride obtained by an ester reaction,
Examples of the reaction product include a reaction product of a polymer product of a styrene monomer and a phenol derivative and o-quinonediazidesulfonic acid described in JP-B-49-17481, and an ester of polyhydroxybenzophenone and o-naphthoquinonediazidesulfonic acid chloride.

A binder can be added to the photosensitive composition containing such a quinonediazide-type positive photosensitive substance, if necessary. For example, a preferable one is a novolak resin soluble in an aqueous alkali solution. Representative examples of such a novolak resin include a phenol-formaldehyde resin, a cresol-formaldehyde resin, a p-tert-butylphenol-formaldehyde resin, a phenol-modified xylene resin, and the like. The amount of the quinonediazide compound in the photosensitive composition is 10 to
It is 50% by weight, more preferably 20 to 40% by weight.
The amount of the binder is 45 to 80% by weight, preferably 50 to 70% by weight in the photosensitive composition.

As the photosensitive substance, a diazo resin represented by a condensate of an aromatic diazonium salt and formaldehyde is also used.

Particularly preferably, a salt of a condensate of p-diazodiphenylamine with formaldehyde or acetaldehyde,
For example, hexafluorophosphate, tetrafluoroborate, a diazo resin inorganic salt which is a reaction product of a perchlorate or a periodate and the condensate, and U.S. Pat.
As described in No. 9, an organic salt of a diazo resin, which is a reaction product of the condensate and sulfonic acids, and the like can be mentioned. Furthermore, diazo resins are preferably used with binders. As such a binder, various polymer compounds can be used. Preferably, a monomer having an aromatic hydroxyl group as described in JP-A-54-98613, for example, N- (4-hydroxyphenyl) ) Acrylamide, N-
(4-hydroxyphenyl) methacrylamide, o-, m
-Or a copolymer of p-hydroxystyrene, o-, m-, or p-hydroxyphenyl methacrylate and other monomers with a hydroxyethyl acrylate unit or hydroxy as described in U.S. Pat. Polymer containing ethyl methacrylate unit as a main repeating unit, natural resin such as shellac, rosin,
Polyvinyl alcohol, polyamide resin described in U.S. Pat.No. 3,751,257, linear polyurethane resin described in U.S. Pat.No. 3,660,097, phthalated resin of polyvinyl alcohol, epoxy resin condensed from bisphenol A and epichlorohydrin, cellulose acetate, Cellulose such as cellulose acetate phthalate is included.

Also as a photosensitive group on the polymer main chain or side chain And those containing a photosensitive polymer as a main component, such as polyesters, polyamides, and polycarbonates. For example, a photosensitive polyester obtained by condensation of phenylenediethyl acrylate with hydrogenated bisphenol A and triethylene glycol as described in JP-A-55-40415, U.S. Pat. No. 2,956,878
And (2-properidene) malonic acid compounds such as cinnamylidenemalonic acid and photosensitive polyesters derived from difunctional glycols.

Further, an aromatic azide compound in which an azide group is bonded to an aromatic ring directly or via a carbonyl group or a sulfonyl group is also included. For example, polyazide styrene, polyvinyl-p as described in U.S. Pat. No. 3,096,311
-Azidobenzoate, polyvinyl-p-azidobenzal, the reaction product of an azidoarylsulfanyl chloride described in JP-B-45-9613 with an unsaturated hydrocarbon polymer, and JP-B-43-21067, JP-B-43-21067. No. 229, 44-22
Polymers having a sulfonyl azide or a carbonyl azide as described in JP-A Nos. 954 and 45-24915 are exemplified.

Furthermore, a photopolymerizable composition comprising an addition-polymerizable unsaturated compound is also included.

The thickness of the photosensitive layer is preferably from 0.05 to 10 μm, more preferably from 0.1 to 2 μm.

In the present invention, the photosensitive substance may further contain a filler, a dye, a dye, a pigment, a surfactant for improving coating properties, and other conventional additives and auxiliaries.

As the silicone rubber used in the silicone rubber layer, the main component is a linear organic polysiloxane having an OH group in the main chain or at the terminal of the main chain having a molecular weight of several thousand to several hundred thousand having repeating units as follows. Are preferred.

Here, n is an integer of 2 or more, and R is an alkyl group having 1 to 10 carbon atoms, a halogenated alkyl group, an alkyl group, a vinyl group,
An aryl group and a silanol group (OH group), wherein R is preferably a methyl group at 60% or more. The silanol group (OH group) may be in the main chain or at the terminal of the main chain, but is preferably at the terminal.

The silicone rubber useful in the present invention is obtained by a condensation reaction of such a silicone base polymer with the following silicone crosslinking agent.

(1) R-SiOR ') (2) R-SiOAc) (3) R-SiON = CR' 2) 2 wherein R is the same meaning as R described above, R 'is a methyl group, an ethyl group And Ac is an acetyl group.

These silicone rubbers are also available as commercial products,
For example, there is YE-3085 manufactured by Toshiba Silicone Co., Ltd.

Further, other useful silicone rubbers are obtained by reacting a base polymer as described above with a silicone oil having the following repeating unit, or a silicone base polymer in which about 3% of R is a vinyl group. It can also be obtained by an addition reaction or a reaction between the silicone oils.

(In the formula, R has the same meaning as R, m is an integer of 2 or more, and n is 0 or an integer of 1 or more.) In order to obtain silicone rubber by such a crosslinking reaction, In addition to the components, copper, zinc, cobalt,
An organic carboxylate of a metal such as lead, calcium, manganese or the like, for example, dibutyltin laurate, tin (II) octoate, cobalt naphthenate, or a catalyst such as chloroplatinic acid is added.

In order to improve the strength of the silicone rubber and obtain a silicone rubber capable of withstanding the frictional force generated during the printing operation, a filler may be mixed. Silicone rubber pre-mixed with filler is commercially available as silicone rubber stock or silicone rubber dispersion.If it is preferable to obtain a silicone rubber film by coating as in the present invention,
RTV or LTV silicone rubber disversions are preferably used. Such examples include silicone rubber disversions for paper coating, such as Syl OFF 23, SRX-257, SH237 manufactured by Toray Silicones.

In the present invention, it is preferable to use a condensation-crosslinking type silicone rubber.

In the present invention, a small amount of a photosensitizer can be contained in the silicone rubber layer in addition to the above components.

The silicone rubber layer preferably contains a silane coupling agent for further improving the adhesiveness.

Examples of the silane coupling agent include the following.

(A) H ₂ NCH ₂ CH ₂ NHCCH ₂ CH ₂ CH ₂ Si (OCH ₃ ) ₃ (C) HS (CH ₂ ) ₃ Si (OCH ₃ ) ₃ (d) CH ₂ CHCHSi (OCOCH ₃ ) ₃ (F) CH ₂ = CHSi (OCH ₂ CH ₃ ) ₃ (g) H ₂ NCH ₂ CH ₂ NH (CH ₂ ) ₃ Si (OCH ₃ ) ₂ (CH ₃ ) (h) Chlorsilane The thickness of the silicone rubber layer is , 0.5 to 100 μm, more preferably 1 to 40 μm.

In the present invention, the mat layer is a discontinuous layer formed by fixing solid particles to a silicone rubber layer.

Here, the term "fixing" means to adhere to the silicone rubber layer by a powdering method without using a developer-soluble binder. In order to adhere to the silicone rubber layer, a means of heat fusion is used, and in this case, the entire solid particles may be thermally fused and adhered, or only the surface of the solid particles may be thermally fused and adhered. Is also good. Alternatively, the surface of the solid particles may be coated with an adhesive layer which is insoluble in the developer and is thermally melted and adheres to the silicone rubber layer.

As the solid particles, those which are substantially transparent to actinic rays for exposure are used, but an ultraviolet absorber may be contained in order to prevent the solid particles from being adversely affected by scattered light. The coverage of the silicone rubber layer with the solid particles is preferably 30% or less, more preferably 20 to 2%.

The solid particles are preferably insoluble in a developer. This is because the developer is not fatigued.

In the present invention, when a lithographic printing plate is used after using solid particles that do not dissolve in a developing solution, the solid particles can be removed by swelling the silicone rubber with the developing solution. This is because the adhesiveness of the rubber layer drops and the rubber layer falls off.

The melting point (mp) of the solid particles is preferably from 60 to 150 ° C. in consideration of the easiness of thermal fusion to the silicone rubber layer.

The shape and size of the solid particles are not particularly limited in the case of the powder before fixing, but the solid particles fixed on the silicone rubber layer have a height of 3 to 20 μm and a size (width) of 20 to 20.
A 0 μm hemisphere, semiellipsoid, or column is preferred, and this shape can be obtained efficiently by heating and fusing a thermoplastic resin.

Specific examples of the solid particles include, for example, silicon dioxide, zinc oxide, titanium oxide, zirconium oxide, glass particles, alumina, starch, polyethylene, polymethyl methacrylate, polystyrene, phenolic resin, ionomer resin, ABS resin, ethylene-vinyl acetate copolymer, Vinyl chloride resin, polyamide resin, fluororesin, polyester resin,
Epoxy resin (before curing), thermoplastic resin such as copolymer resin of styrene and (meth) acrylic acid or methacrylic acid ester, and the like, preferably thermoplastic resin particles,
Alternatively, particles coated with a thermoplastic resin may be used. These may be used in combination of two or more. US Patent
Matting agents described in 2,701,245 and 2,992,101 can be used.

The fountain solution unnecessary plate material of the present invention is manufactured, for example, as follows.

The composition solution to constitute the photosensitive layer is coated and dried on a support using a normal coater such as a reverse roll coater, an air knife coater, or a Meyer bar coater, or a rotary coating device such as a whey coater. After curing, if necessary, a mounting layer is applied on the photosensitive layer in the same manner, and after drying, a silicone rubber solution is applied on the adhesive layer in the same manner, and usually heat-treated at a temperature of 100 to 120 ° C. for several minutes. And sufficiently cured to form a silicone rubber layer.

Next, the solid particles are substantially uniformly dispersed on the silicone rubber layer and are thermally fused. Thus, the printing plate shown in FIG. 1 is obtained.

Another method for obtaining a discontinuous mat layer to which solid particles are fixed is to use a resin liquid obtained by adding a curing agent to a liquid thermosetting resin, for example, an epoxy resin, a phenol resin, an unsaturated polyester resin, or the like. A method of spraying droplets on the rubber layer and curing the resin by subsequent heating,
The solid thermosetting resin is pulverized to a powder, then classified, only particles having a certain range of particle size are collected, sprayed on the silicone rubber layer, and then heated to melt the particles. A method of curing the resin at the same time as the application can be used. In addition, a method in which a solution or dispersion of an organic solvent in which a resin is dissolved or dispersed, an aqueous solution, a dispersion, an emulsion solution, or the like is sprayed in the form of droplets, followed by drying and curing by heating can be used. This method is advantageous as an industrial production method because granulation and application of mat layer particles can be performed simultaneously. By using these methods, a mat layer in which solid particles are insoluble in a developer can be obtained.

Next, a method of producing a dampening solution-free plate using the dampening solution-free plate of the present invention will be described.

A positive film as a manuscript is brought into vacuum contact with the plate surface,
Expose. As a light source for this exposure, a mercury lamp, a carbon arc lamp, a xenon lamp, a metal halide lamp, a fluorescent lamp, or the like that generates abundant ultraviolet rays is used.

At this time, the vacuum adhesion is improved by the presence of the mat layer.

After exposure, development with a developer removes the unexposed portions of the silicone rubber layer and the photosensitive layer. At this time, the solid particles that are not removed together with the silicone rubber layer drop off from the silicone rubber layer due to a decrease in the adhesion between the solid particles and the silicone rubber layer because the silicone rubber swells in the developer.

As described above, it is possible to obtain a printing plate having a concave image portion formed in an unexposed portion.

[Effects of the Invention] According to the present invention, a fountain solution-free lithographic printing plate material which improves vacuum adhesion, simplifies a plate making process, reduces developer fatigue, and has good dot reproducibility is provided. be able to.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1 A 10-μm-thick photopolymerizable adhesive layer (photosensitive layer) having the following composition was provided on a brush-polished aluminum plate.

a. Solid matter (polycondensate of bisphenol A, propylene oxide, maleic anhydride) 40% by weight of unsaturated polyester "Polylite TDR-1131R" manufactured by Dainippon Ink and Chemicals, Inc. b. 4 mol of glycidyl methacrylate and 1 mol of xylylenediamine 55% by weight c. Benzoin methyl ether 5% by weight RTV silicone rubber version "YE-3085" manufactured by Toshiba Silicone Co., Ltd. on this photopolymerizable adhesive layer (photosensitive layer)
Diluted with n-heptin, applied and dried to a thickness of 2 μm
Was provided.

Next, styrene: methyl methacrylate: acrylic acid: butyl acrylate = 30: 30: 30: 10 molar ratio, melting point 95
After crushing the copolymer resin at ℃, it was classified and the particle size was 10-60 μm.
The powder obtained by separating the particles was powdered on a silicone rubber layer and heated at 120 ° C. for 30 seconds.

Particle height is 15μm on average and size (width) is 20 ~ 200μ
m, a mat layer having a silicone rubber layer coverage of 8% was obtained. A positive film was applied on this plate material, and the light of a 3 Kw ultra-high pressure mercury lamp was irradiated from a distance of 1 m for 3 minutes at a vacuum contact time of 30 seconds and immediately developed with n-heptane. The rubber layer and the mat layer were removed, and a lithographic printing plate faithfully reproducing a positive film was obtained.

The particles of the matte layer did not dissolve in the developer and could be removed by filtration and did not fatigue the developer at all.

Comparative Example 1 A plate material was obtained in the same manner as in Example 1 except that the mat layer was not provided. When this plate material was used, burning occurred even after 5 minutes of vacuum contact, and the reproduction of halftone dots was insufficient.

Example 2 The following primer layer composition was applied onto a degreased smooth aluminum plate having a normal size so as to have a dry film thickness of 2 μm, and was heated and cured at 120 ° C. for 5 minutes.

Epicoat 1001 (Bisphenol A-based epoxy resin manufactured by Shell Chemical Co., Ltd., epoxy equivalent is 450 to 500) 100 parts by weight Methyltetrahydrophthalic anhydride 36 parts by weight 2,4,6-tris (dimethylaminomethyl) phenol 10
Parts by weight methyl cellosolve acetate 600 parts by weight toluene 600 parts by weight methyl ethyl ketone 600 parts by weight The following photosensitive composition containing a silane coupling agent and an organotin compound is dried on an aluminum plate coated with the above primer layer in a dry film thickness. It was applied to a thickness of 0.25 μm and dried.

10 parts by weight of a photosensitive unsaturated polyester obtained by polycondensation of p-phenylenediacrylate and 1,4-dihydroxyethyloxycyclohexane at a ratio of 1: 1 (molar ratio) 10 parts by weight 1-methyl-2-benzoylmethylene-β-naphthothiazoline 0.6 part by weight Part N- (β-aminoethyl) aminomethylphenethyltrimethoxysilane 0.4 part by weight Dibutyltin dioctanoate 0.8 part by weight Sumitone cyanine blue VH514 (Phthalocyanine blue pigment manufactured by Sumitomo Chemical Co., Ltd.) 2 parts by weight Methyl cellosolve acetate 600 parts by weight Toluene 300 parts by weight Part Next, the following silicone rubber composition was applied on the above-mentioned photosensitive layer so as to have a dry film thickness of 2.0 μm, and dried to obtain a cured silicone rubber layer.

Dimethylpolysiloxane having hydroxyl groups at both ends (molecular weight: about 600,000) 100 parts by weight Methylhydrogenpolysiloxane having trimethylsilyl groups at both ends (molecular weight: about 2500) 3.5 parts by weight 1-methoxysilylpropyl-3.5-diallyl isocyanurate 3.3 parts by weight Diptyl tin dioctanoate 3.3 parts by weight Izopar G (manufactured by Esso Chemical Co., Ltd.) 2000 parts by weight The following epoxy resin composition is applied to the surface of the silicone rubber layer obtained as described above by an electrostatic air type spray. At 120 ° C. for 3 minutes.

Epicoat 1001 100 parts by weight Methyltetrahydrophthalic anhydride 36 parts by weight 2,4,6-tris (dimethylaminomethyl) phenol 10
Parts by weight Methyl cellosolve 500 parts by weight A dampening water-free lithographic printing plate material having a mat layer having an average particle size of 8 μm, a size of 15 to 150 μm, and a silicone rubber layer coverage of 10% was obtained.

A positive film is overlaid on this plate and vacuum-adhered to it to make Nuark ET26V UDNS ULTRA-PLUS FLIP-TOP PLATE MAKER
And then immersed in a developer consisting of 90 parts by weight of Isopar H (manufactured by Esso Chemical), 7 parts by weight of diethylene glycol monobutyl ether, 3 parts by weight of diethylene glycol monoethyl ether and 5 parts by weight of diethyl succinate for 1 minute, After rubbing with a developing pad for 1 to 2 minutes, the unexposed portions of the photosensitive layer, silicone rubber layer, and mat layer were removed. In this way, a fountain solution-free lithographic printing plate was obtained in which the image of the positive film was faithfully reproduced over the entire surface of the printing plate.

Heidelberg GTO with the dampening water supply removed
Attached to the printing machine, TOYO KING ULTRA-T manufactured by Toyo Ink
When printing was performed using UK AQUALES G-red ink, 20 000 printed materials without stains were obtained, and the reproducibility of the highlight portion was good.

In this example, similarly to Example 1, the particles of the mat layer were not dissolved in the developing solution, and the particles of the mat layer could be removed by filtration, so that the developing solution was not fatigued.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view of an essential part showing an example of a fountain solution unnecessary plate material of the present invention. 1: Support 2: Photosensitive layer 3: Silicone rubber layer 4: Mat layer

Claims (1)

(57) [Claims] 1. A lithographic printing plate material which does not require a fountain solution and has a photosensitive layer and a silicone rubber layer in this order on a support, wherein a developer-soluble or insoluble binder is not used on the silicone rubber layer. Has a discontinuous mat layer in which the solid particles are fixed by heat fusion, and the solid particles fall off due to a decrease in the adhesive force between the solid particles and the silicone rubber layer due to swelling of the silicone rubber layer by the developer. A lithographic printing plate material requiring no dampening solution, characterized by being particles.