JPH0159580B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel method for producing a lithographic printing plate and a novel photosensitive material for a lithographic printing plate for use in this method.

Conventionally, photosensitive materials for printing plates that include a photoconductive layer and utilize electrophotography are known, for example, photosensitive materials for printing plates that include a photoconductive insulating layer, a photoresist layer, a metal plate layer, and a support. Photosensitive materials have been proposed.

To manufacture printing plates using this photosensitive material, the photoconductive layer is first uniformly charged, and an electrostatic latent image is formed on the photoconductive layer by imagewise exposure using a light beam that is not sensitive to the photoresist layer. This latent image is then developed with toner, the toner image is exposed with or without fixation under conditions different from the previous exposure conditions to harden the exposed areas of the photoresist layer, and then the toner image and the photoconductor are exposed. This method required a complicated process of removing the uncured photoresist with a solvent, etching the metal plate layer, and removing the photoresist remaining on the metal plate. . Manufacturing high-quality printing plates not only requires skill, but also limits resolution as the electrostatic latent image formed on the photoconductive layer is developed dryly. Due to the removal and etching operations of the metal plate layer, the sharpness of the final printed image was still unsatisfactory.

In order to solve such drawbacks, first, a photosensitive material having a conductive support having a hydrophilic surface, a positive photosensitive layer, and a photoisoelectric insulating layer was prepared by: (1) photoconductivity of the photosensitive material; forming an electrostatographic latent image on the layer (2) developing the latent image with a liquid developer containing developer particles that are opaque to light at wavelengths to which the positive-working photosensitive layer is sensitive; (3) exposing the positive photosensitive layer to light through the developed image obtained in step (2); (4) selectively removing a portion of the positive photosensitive layer that does not have the developed image; the positive-working photosensitive layer and the photoconductive insulating layer are provided on the support either as the same layer or separately in this order, and the photoconductive insulating layer is substantially can be charged to both positive and negative polarities, and the step
(4) A method for producing a lithographic printing plate characterized by having a property that does not inhibit selective removal of a positive-working photosensitive layer, a conductive support having a hydrophilic surface, a positive-working photosensitive layer, and a photoconductive insulating layer. The positive photosensitive layer and the photoconductive insulating layer are provided on the support as the same layer or separately in this order, and the photoconductive insulating layer is A photosensitive material for lithographic printing plates is proposed by the same applicant, which is characterized in that it can be charged to substantially both positive and negative polarities and that it does not inhibit the selective removal of a positive photosensitive layer having a developed image. (Tokkai Sho)
57-90648).

Although this method was able to eliminate the drawbacks of the conventional method mentioned above and to some extent achieved the objectives in terms of simplifying the process and obtaining excellent resolution, it was not possible to use a positive photosensitive layer as the photosensitive layer. This was useful when obtaining a positive image from a positive original or a negative image from a negative original. Reverse development had to be performed, which required a slightly more complicated development process than normal development.

In the above method, the present inventor was able to obtain a lithographic print having a positive image with excellent resolution from a negative original by normal development by using a negative photosensitive layer in place of the positive photosensitive layer.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for producing a lithographic printing plate having a positive image from a negative image using electrophotography.

Another object of the present invention is to provide a photosensitive material for lithographic printing plates used in the above method.

That is, the present invention provides electrophotographic processing of a photosensitive material having a negative photosensitive layer and a photoconductive insulating layer as the same layer or two layers with a negative photosensitive layer as an underlying layer on a conductive support having a hydrophilic surface. processing to form an electrostatic latent image on the photoconductive insulating layer and developing the latent image with developer particles that are opaque to light at wavelengths to which the negative-working photosensitive layer is sensitive; Production of a lithographic printing plate, characterized in that the negative-working photosensitive layer is imagewise exposed to light, and then the unexposed areas of the negative-working photosensitive layer or the unexposed areas and a photoconductive insulating layer provided thereon. on a conductive support with a method and a hydrophilic surface;
It has a negative-tone photosensitive layer and a photoconductive insulating layer in the same layer or as two layers with a negative-tone photosensitive layer as an underlying layer, and the photoconductive insulating layer is capable of forming an image of developer particles electrophotographically. , the developer particles are opaque to light of a wavelength to which the negative photosensitive layer is photosensitive, and the photoconductive insulating layer has a property that does not inhibit selective removal of the negative photosensitive layer. A photosensitive material for lithographic printing.

The method of the present invention will be explained with reference to the drawings. FIG. 1 sequentially illustrates the manufacturing process of a lithographic printing plate according to the present invention. In step a of FIG. 1, a negative photosensitive layer 2 is provided on a grounded conductive support 3. The surface of the photoconductive insulating layer 1 is charged with a charger 4 . The charger used is of the corotron type commonly used in electrostatic photography. Next, image exposure (b) is performed using the lamp 5 to remove the electric charge on the non-image area on the photoconductive insulating layer 1. At this time, if a positive original is used as the original 6, a positive latent image will be obtained, and if a negative original is used, a negative latent image will be obtained. The photosensitive plate on which the electrostatic latent image has been formed is then subjected to a liquid development step c to form a toner image 7. The development time varies depending on the charging potential of the photoreceptor, the zeta potential of the toner, the development electrode, and the development method, but it usually takes a few seconds to one minute to reach a sufficient density to be used as a photopattern mask in the next step. is obtained. As shown in FIG. 1, when the photoconductive insulating layer is to be charged positively, a toner of negative polarity is used, and when the photoconductive insulating layer is to be charged negatively, a toner of positive polarity is used. Note that when liquid development is performed, a development electrode is generally used.

After the development has been completed, the developing solution is removed from the photosensitive plate using a squeegee, and then the entire surface is exposed to light using, for example, an ultraviolet lamp 8.
Perform the process. As a result of this exposure, the non-image area of the negative photosensitive layer (the area where the photoconductive layer does not have a toner image) is irradiated with ultraviolet rays and becomes insoluble. When the photosensitive plate that has been fully exposed in step d is treated with an alkaline solution in the melting step e-1 or e-2, the non-irradiated area of the negative photosensitive layer becomes soluble and the irradiated area becomes insoluble. The image area (non-irradiated area) is removed, the non-image area (irradiated area) remains on the support, and a lithographic printing plate having a positive image as opposed to a negative image is obtained. When making a lithographic printing plate by a dissolving process, the photoconductive layer 1 may be left on the photosensitive layer 2 as in the e-1 process, or the photoconductive layer is removed and the photosensitive layer is removed as in the e-2 process. 2 may remain on the support 3.

As another embodiment of the present invention, a photosensitive material can be used in which an intermediate layer 9 is provided between the photoconductive insulating layer 1 and the negative photosensitive layer 2 (see FIG. 4). This intermediate layer is conductive in order to promote the retention of charges of opposite polarity to the charges loaded on the surface of the photoconductive insulating layer on the negative photosensitive layer side of the conductive support. By providing the layer, it is possible to prevent the photoconductive insulating layer from penetrating and mixing with the negative photosensitive layer. This intermediate layer is a water-soluble resin with appropriate conductivity that is insoluble with respect to the negative photosensitive layer, and is dissolved and removed in the dissolution e-2 step, but at the same time the photoconductive insulating layer having the toner image is also detached. As a result, a lithographic printing plate having a positive-working photosensitive layer on the support can be obtained.

In the photosensitive material for lithographic printing plates according to the present invention, when the photoconductive insulating layer and the negative-tone photosensitive layer are formed as the same layer, this layer consists of the photoconductive material powder, the insulating binder resin and the negative-tone photosensitive layer. The photosensitive agent solution can be mixed to form a uniform dispersion, which can be applied to the grained surface of the conductive support and dried.

In general, the thickness of the photoconductive insulating layer affects chargeability, optical transparency, development time, and resolution;
Best results are obtained within the range 0.5-5μ, preferably 1-2μ.

The thickness of the intermediate layer depends on the permeability of the solvent used in the dissolution process and the resolution, and is usually 0.5 to 5 μm.
Preferably it is within the range of 0.2 to 0.5μ.

Examples of the photoconductive material used in the photoconductive insulating layer of the present invention include many conventionally known photosensitive materials for electrophotography.
It is preferable to use an insulating binder dispersed or dissolved in a resin, and to use one that does not absorb the absorption wavelength light of the underlying positive photosensitive layer, or to reduce the thickness of the photoconductive insulating layer. It is preferable to make it as thin as possible to increase the amount of transmitted light. The photoconductive insulating layer can be used by being charged either positively or negatively, but photoconductive materials suitable for positive corona charging include inorganic materials such as Se, Se-Te, and PbO, as well as anthracene, perylene, tetracene, Low molecular weight substances such as carbazole, tetrabenzyl-p-phenylenediamine, acylhydrazone derivatives, oxadiazole derivatives, pyrazoline derivatives, imidazolone derivatives, imidazothion derivatives, benzimidazole derivatives, benzoxazole derivatives, benzthiazole derivatives, indigo, metal-free Organic pigments such as phthalocyanine, metal phthalocyanine, squarium, and dimethylperylimide, and organic polymer substances such as poly-N-vinylcarbazole, polyacenaphthylene, polyvinylanthracene, polyvinylpyrene, polyvinyltetracene, and polyvinylperylene are used. Photoconductive materials suitable for negative corona charging include ZnO,
Inorganic materials such as CdS and TiO, low molecular weight substances such as trinitrofluorenone, tetranitrofluorenone, dinitroanthracene, and tetracyanopyrene, organic materials such as chlorodiane blue, poly-N-vinylcarbazole and 2,4,7- Complexes such as trinitrofluorenone are used. As a photoconductive material suitable for amphoteric charging, a combination of the organic substance and a binder resin can be used.
In particular, materials that exhibit high sensitivity for practical use include metal-free phthalocyanine, metal phthalocyanine,
Examples include oxadiazole derivatives and virazoline derivatives. Furthermore, photosensitive materials containing a charge generating agent and a charge transporting agent, copolymers of alkali-soluble resins and photoconductive substances such as carbazole, etc. can also be used.

The photoconductive insulating layer does not inhibit selective removal of the positive photosensitive layer in the dissolution e-1 and e-2 steps, that is, its non-image area is dissolved and removed together with the non-image area of the negative photosensitive layer. Preferably, it contains an alkali-soluble resin. Such alkali-soluble resins are preferably insulating resins with film-forming properties that serve as binders for high-molecular organic photoconductive substances or as solvents for low-molecular organic photoconductive substances. Examples of such resins include, for example. Phenol-formaldehyde resin, metacresol formaldehyde resin, styrene-maleic anhydride copolymer, polyacrylic acid-polyacrylamide copolymer, ethylene glycol fumarate copolymer, methyl vinyl ether-maleic anhydride copolymer, acryloyl Examples include synthetic resins such as glycine-vinyl acetate copolymer, polyvinylpyrrolidone, polyvinyl alcohol, polyamide, alkali-soluble azide resin, and halogenated polystyrene, and natural resins such as silica, protein, and glue.

As a binder for the photoconductive material particles used in the photoconductive insulating layer, insulating resins such as polyethylene terephthalate, polyimide, polycarbonate, polyacrylate, polymethyl methacrylate, etc. can be used to improve the chargeability of the layer. Polyvinyl fluoride, polyvinyl chloride, polyvinyl acetate, polystyrene, styrene-butadiene copolymer, polymethacrylate, silicone resin, chlorinated rubber, epoxy resin, pure and modified alkyd resin, polyethyl methacrylate, poly-n-butyl methacrylate, cellulose acetate. ,
Examples include ketone resin, polyethylene, polypropylene, polyacrylonitrile, rosin derivatives, polyvinylidene chloride, and nitrocellulose.

As an optional intermediate layer between the photoconductive insulating layer and the positive photosensitive layer, a water-soluble resin having suitable conductivity, such as polyvinyl alcohol,
Alkylhydroxyalkylcellulose, polyacrylic acid and its derivatives, polyacrylamide, polyvinylpyrrolidone, polyvinylmethyl ether, a reaction product of maleic anhydride and a vinyl or acrylic compound, and the like are used.

The composition of the negative photosensitive layer used in the present invention is:
For example, diazo compounds or diazo resins alone as described in US Pat. No. 2,714,066, US Pat.
There are mixtures of diazo compounds or diazo resins and carriers as described in US Pat. No. 1,074,392.

Diazo compounds include diazonium salts and diazo resins typified by condensates of P-diazophenylamine and formaldehyde.

Particularly preferred diazo compounds include salts of P-diazodiphenylamine, such as phenol salts,
fluorocaprate, and triisopropylnaphthalenesulfonic acid, 4,4′-biphenyldisulfonic acid, 5-nitroortho-toluenesulfonic acid,
5-sulfosalicylic acid, 2.5-dimethylbenzenesulfonic acid, 2-nitrobenzenesulfonic acid, 3
-Chlorobenzenesulfonic acid, 3-promobenzenesulfonic acid, 2-chloro-5-nitrobenzenesulfonic acid, 2-fluorocaprylnaphthalenesulfonic acid, 1-naphthol-5-sulfonic acid, 2
-Methoxy-4-hydroxy-5-benzoyl - A compound having two or more diazo groups in one molecule, such as a condensate of formaldehyde and a salt of a sulfonic acid such as benzenesulfonic acid or para-toluenesulfonic acid. . Other desirable diazo compounds include condensates of 2.5-dimethoxy-4-P-tolylmercaptonebenzenediazonium and formaldehyde, including the above salts, condensates of 2.5-dimethoxy-4-morpholinobenzenediazonium and formaldehyde or acetaldehyde, and There is a compound described in JP-A-48-33907.

Still other useful diazo compounds, U.S. Pat.
2649373.

A particularly preferred diazo compound is 2-methoxy-4-hydroxy-5-benzoylbenzenesulfonate, a condensate of P-diazodiphenylamine and formaldehyde. Examples of carriers used with diazo compounds include
2-hydroxyethyl methacrylate copolymers as described in JP-A No. 7364 and JP-A-50-118802; copolymers of monomers having aromatic hydroxyl groups as described in JP-A-54-9861; Polymer, Japanese Unexamined Patent Publication 1973
The polymer of β-hydroxyethyl (meth)acrylate and the copolymer containing 50% or more of β-hydroxyethyl (meth)acrylate described in JP-A-30604, and the above (described in JP-A-56-9697) A meth)acrylate polymer or copolymer in which part of it is replaced with a low molecular weight polyurethane resin having a hydrophilic ether group is used.

Further, other photopolymerizable compositions having negative effects will be explained. The photopolymerizable composition consists of a binder, an addition polymerizable unsaturated monomer, and a photopolymerization initiator. The binder of the photopolymerizable composition is
Methyl (meth)acrylate/(meth)acrylic acid copolymer, half ester and half amide of styrene/maleic anhydride copolymer, benzyl (meth)acrylate/(meth)acrylic acid copolymer, benzyl (meth)acrylate /itaconic acid copolymer, styrene/itaconic acid copolymer, vinyl acetate/crotonic acid copolymer, acidic cellulose phthalate, (meth)acrylic acid/styrene/alkyl (meth)acrylate copolymer, etc. can be used. .

As the unsaturated monomer, compounds having at least one addition-polymerizable unsaturated group are useful, and particularly preferred are ethylene glycol di(meth)
Acrylate, polyethylene glycol di(meth)acrylate, trimethylolethane tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, neopentylglycol di(meth)acrylate, pentaerythritol and dipentaerythritol tri-, tetra- or Hexa(meth)acrylate, epoxy di(meth)acrylate, oligoacrylate as disclosed in Japanese Patent Publication No. 52-7361,
Examples include acrylic urethane resins and acrylic urethane oligomers as disclosed in Japanese Patent Publication No. 48-41708.

As photopolymerization initiators, vicinal polyketaldonyl compounds disclosed in US Pat. No. 2,367,660, US Pat. Nos. 2,367,661 and 2,367,670 are used.
α-carbonyl compounds disclosed in US Pat. No. 2,448,828, acyloin ethers disclosed in US Pat. No. 2,722,512; acyloin compounds, polynuclear quinone compounds disclosed in U.S. Pat. No. 3,046,127 and No. 2,951,758, triallylimidazole dimer/p as disclosed in U.S. Pat.
- Combination of aminophenyl ketones, Special Publication 1977-
Benzothiazole compounds disclosed in Japanese Patent Publication No. 48516, benzothiazole compounds/trihalomethyl-s-triazine compounds disclosed in JP-A-54-74887, and U.S. Pat.
Examples include acridine and phenazine compounds disclosed in No. 3751259.

In addition to the above, it is preferable to add a thermal polymerization inhibitor, such as hydroquinone, p-methoxyphenol, di-t-butyl-p-cresol, pyrogallol, t-butylcatechol, benzoquinone, 4.4'-thiobis(3 -methyl-6-t
-butylphenol), 2,2'-methylenebis(4
-Methyl-6-t-butylphenol), 2-mercaptobenzimidazole, etc. are useful, and in some cases, dyes or pigments, and PH indicators etc. as printing agents may be added for the purpose of coloring the photosensitive layer. You can also do it.

After exposing the photosensitive layer to ultraviolet light, the unexposed areas of the photoconductive layer where toner was present are selectively eluted and removed using a developer. The composition of the developer varies depending on the type of diazo compound and carrier used, but generally contains sodium salt of lauryl alcohol sulfate (Monogen Y-100, manufactured by Daiichi Kogyo Seiyaku KK, trade name), sodium alkyl lauryl sulfate, Wetting agents such as sodium octyl sulfate, ammonium salt of lauryl sulfate, sodium xylene sulfonate, monosodium salt of N,N-dihydroxyethyleneglycine, or an aqueous solution containing an alkali such as an inorganic alkaline agent or an organic amine compound are used. In this case, alcohols such as ethylene glycol monobutyl ether, pencil alcohol, ethyl acetate,
It is desirable to add a small amount of a water-miscible organic solvent such as a carboxylic acid ester such as butyl acetate; a ketone such as methyl isobutyl ketone; or an alkyl-substituted aromatic hydrocarbon such as xylene.

A negative photosensitive layer having such a composition is usually coated on a conductive support in an amount of about 0.5 to 7 g/m ² .

The mixing ratio of the photoconductive material, insulating resin, and alkali-soluble resin in the photoconductive insulating layer of the photosensitive material for lithographic printing plates according to the present invention includes photoconductivity, chargeability, light transmittance, developer dissolution and permeation speed. determined by. Good properties can be obtained at a ratio of 5 to 30% by weight of the photoconductive material, 0 to 30% by weight of the insulating resin, and 50 to 85% by weight of the alkali-soluble resin. When a low resistance alkali soluble resin is used, the charging property is improved compared to an insulating resin, and when a high resistance alkali soluble resin is used, it is not necessary to mix the insulating resin. When forming the photoconductive insulating layer and the negative photosensitive layer as the same layer, 5 to 30% by weight of the photoconductive material, 0 to 30% by weight of the insulating resin, and 50% by weight of the photosoluble substance.
A mixing ratio of ~85% by weight can be used.

The conductive support in the lowermost layer of the photosensitive material for lithographic printing plates according to the present invention is made of, for example, a surface-treated aluminum plate, and has a positive-working photosensitive layer on the surface-treated surface. Preferred aluminum plates include pure aluminum plates and aluminum alloy plates, as well as plastic films laminated or vapor-deposited with aluminum. The surface of the aluminum plate is preferably subjected to a surface treatment such as graining treatment, immersion treatment in an aqueous solution of sodium silicate, potassium fluorozirconate, phosphate, or the like, or anodization treatment.
These surface treatments, that is, hydrophilization treatments, are performed to make the support surface hydrophilic, but at the same time prevent harmful reactions with the positive photosensitive layer provided on the support and improve adhesion with the photosensitive layer. can be improved.

The liquid developer for electrophotography used in the liquid development step c of the method of the present invention is a well-known developer such as carbon black dispersed in gasoline, kerosene, or carbon tetrachloride, and has electrical properties. For uniformity, it is possible to use a product improved by using a control agent such as alkyd resin or linseed oil (see Japanese Patent Publication No. 13424/1983). Both negatively charged and positively charged toners can be used.Negatively charged toners include carbon black, lead chromate, charcoal, etc., dispersed in aliphatic hydrocarbons, gasoline, cyclohexane, pentane, CCl ₄ , etc.
There are toners containing linseed oil, polyethylene, silica, etc. as control agents, and positively charged toners such as carbon black, phthalocyanine blue, charcoal, vermilion red, etc., and aliphatic hydrocarbons, kerosene, cyclohexane, pentane, etc.
Some are dispersed in CCl ₄ , etc., with addition of alkyd resin, versamide, tergitol, etc. as control agents. Developer particles with a size of 1 μm or less are used, which is suitable for obtaining high-resolution images.

Although the present invention has been described above regarding the case of liquid development, the present invention is not limited to this, and cascade development, magnetic brush development, etc. can also be used.

Hereinafter, the present invention will be specifically explained with reference to Examples.

Example 1 A grained aluminum plate with a thickness of 0.24 mm was anodized in a sulfuric acid bath to form an oxide film of approximately 2.7 g/m ² , thoroughly washed, dried, and adjusted with the following formulation*. The resulting photosensitive solution was coated using a wheeler to obtain a photosensitive layer having a dry coating weight of 1.2 g/m ² .

*(Photosensitive liquid formulation) 2-hydroxyethyl methacrylate copolymer (described in Example 1 of US Pat. No. 1,505,739) 0.87g 2-methoxy-, a condensate of P-diazodiphenylamine and paraformaldehyde 4-Hydroxy-5-benzoylbenzenesulfonate 0.1g 2-methoxyethanol 6g Methanol 6g Ethylene dichloride 6g On top of this, a photosemiconductor layer is added to the next photosensitive solution※※
After dispersing with an ultrasonic dispersion liquid for 5 minutes, it was coated with a wire bar and dried at 70°C for 1 minute. The solid content coating amount of the optical semiconductor layer is 2.5g/m ²
It is.

※※ Novolac type phenolic resin (33% in isopropyl alcohol) 12g - (ethyl acrylate ₆₂ - methyl methacrylate ₂₅ - methacrylic acid ₁₃ -) (25% in ethyl alcohol) 4g Phthalocyanine pigment (Sumikaprint GN-
O, manufactured by Sumitomo Chemical Co., Ltd.) 1g Toluene 25g This photosensitive plate was positively charged with a corona using a corona charger set to a corona charging voltage of +6000V.
Next, the negative transmission original was exposed to irradiation light of 60 lux from a tungsten bulb for 2 seconds. Next, in the dark, use a liquid developer containing negative polarity toner (manufactured by Ricoh).
The sample was placed face down in a stainless steel plate filled with MRP-610) and developed with toner for 10 seconds to obtain a negative toner image on the photosensitive plate. Next, the entire surface was exposed for 60 seconds using a Fujifilm A3 printer (exposure material for PS plates), and then for 1 minute in a solution prepared by diluting Fujifilm's stock image solution DN-3C for PS plates to 1/2 with water. Upon development, a lithographic printing plate having a positive image was obtained. When offset printing was performed using this lithographic printing plate, more than 40,000 clear prints were obtained.

Example 2 A photosensitive solution prepared according to the following photosensitive solution formulation* was applied onto the same aluminum support as in Example using a wheeler to obtain a photosensitive layer with a dry coating weight of 1.7 g/m ² .

*Poly-p-vinylphenol cinnamate ester 25g 5-nitroacenaphthene 3g 2,6-di(4'-azidobenzal)-4-methifrecyclohexanone 1.5g Methyl ethyl ketone 200g Toluene 30g On top of this, the following formulation* *An optical semiconductor layer with a dry coating amount of 1.9 g/m ² was provided by manual cutting in the same manner as in Example 1.

※※ -(Ethyl acrylate ₆₂ - Methyl methacrylate ₂₅ - Methyl acrylic acid ₁₃ -) (in 25% ethyl alcohol) 12 g Microlis 4G-T (phthalocyanine pigment manufactured by Ciba Geigy) 1.5 g Toluene 25 g This photosensitive plate was prepared using the same method as in Example 1. A negative image with toner was obtained on a photosensitive plate. Next, Fujifilm A3 printer (PS plate exposure machine)
After exposing the _entire surface _to light for ₉₀ seconds at
A lithographic printing plate having a positive image was obtained by immersing it in a developer containing 3 parts by weight (aqueous solution) and 955 parts by weight for about 40 seconds, washing with water, and drying. When offset printing was performed using this lithographic printing plate, more than 80,000 clear prints were obtained.

[Brief explanation of drawings]

Figures 1 a to e-2 are diagrams for explaining the steps of the method of the present invention, and Figures 2, 3, and 4 are diagrams showing the outline of the structure of the photosensitive material for lithographic printing plates of the present invention. be. Codes in the figure: 1, 1'...photoconductive insulating layer, 2...
Negative photosensitive layer, 3... Conductive support, 4... Charger, 5... Lamp, 6... Original, 7... Toner image, 8... Ultraviolet lamp, 9... Intermediate layer.

Claims (1)

[Scope of Claims] 1. A photosensitive material having a negative photosensitive layer and a photoconductive insulating layer as the same layer or two layers with a negative photosensitive layer as the lower layer on a conductive support having a hydrophilic surface is electrophotographically prepared. to form an electrostatic latent image on the photoconductive insulating layer, and develop the latent image with developer particles that are opaque to light at a wavelength to which the negative photosensitive layer is sensitive. A lithographic printing plate characterized in that the negative photosensitive layer is exposed to light through a developed image, and then a non-exposed area of the negative photosensitive layer or a photoconductive insulating layer provided on the non-exposed area and the non-exposed area. manufacturing method. 2. The method for producing a lithographic printing plate according to claim 1, wherein the negative photosensitive layer and the photoconductive insulating layer are composed of two layers, and an intermediate layer is provided between the two layers. 3. On a conductive support having a hydrophilic surface, a negative-tone photosensitive layer and a photoconductive insulating layer are provided in the same layer or as two layers with a negative-tone photosensitive layer as an underlying layer, and the photoconductive insulating layer is an electrophotographic The developer particles are opaque to light at a wavelength to which the negative photosensitive layer is photosensitive, and the photoconductive insulating layer is opaque to light at a wavelength to which the negative photosensitive layer is photosensitive. A photosensitive material for planographic printing characterized by having a property that does not inhibit selective removal. 4. The photosensitive material for lithographic printing plates according to claim 3, comprising two layers: a negative photosensitive layer and a photoconductive insulating layer, and an intermediate layer is provided between the two layers.