Classifications

• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
  • G03G5/00—Recording-members for original recording by exposure, e.g. to light, to heat or to electrons; Manufacture thereof; Selection of materials therefor
  • G03G5/14—Inert intermediate or cover layers for charge-receiving layers
  • G03G5/147—Cover layers
  • G03G5/14708—Cover layers comprising organic material
  • G03G5/14713—Macromolecular material
  • G03G5/14791—Macromolecular compounds characterised by their structure, e.g. block polymers, reticulated polymers, or by their chemical properties, e.g. by molecular weight or acidity
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
  • G03G5/00—Recording-members for original recording by exposure, e.g. to light, to heat or to electrons; Manufacture thereof; Selection of materials therefor
  • G03G5/14—Inert intermediate or cover layers for charge-receiving layers
  • G03G5/147—Cover layers
  • G03G5/14708—Cover layers comprising organic material
  • G03G5/14713—Macromolecular material
  • G03G5/14786—Macromolecular compounds characterised by specific side-chain substituents or end groups

Definitions

• Requirements of offset printing plate precursors for obtaining satisfactory prints are such that an original should be reproduced faithfully on the photoreceptor; the surface of a photoreceptor should have affinity with an oil-desensitizing solution, so as to render non-image areas sufficiently hydrophilic and, at the same time, should have water resistance; and that a photoconductive layer having an image formed thereon is not released during printing and is well receptive to dampening water, so that the non-image areas hold the hydrophilic properties enough to be freed from stains even on printing a large number of prints.
• hydrophilic polymer due to the limitations on the chemical structure of the hydrophilic polymer, it is difficult to exclude all adverse influences of the surface layer upon the functions of an electrophotographic photoreceptor, such as charging properties, quality of a reproduced image (e.g., dot reproducibility and resolving power of image areas, resistance to background fog of nonimage areas, etc.), and light sensitivity.
• the former are those having functional groups capable of forming hydroxyl groups through decomposition as disclosed in Japanese Patent Application Nos. 8217/1988 and 90185/1988, those having functional groups capable of forming carboxyl groups through decomposition as disclosed in Japanese Patent Application Nos. 11250/1988 and 113458/1988 and those-having functional groups capable of forming thiol groups, amino groups, phosphono groups or sulfo groups through decomposition as disclosed in Japanese Patent Application Nos. 134357/1988 and 135705/1988.
• the resin containing at least one polymeric component having a functional group represented by the above described General Formula (I) and/or General Formula (II) can previously be cross-linked and in this case, the resin has water proof property, which is preferable when realizing the hydro philic property through reaction with a processing solution for rendering hydrophilic.
• the lithographic printing plate precursor of the present invention is not sensitive to environmental influences during plate making, is very excellent in storage property before processing and is capable of undergoing rapidly a processing for rendering hydrophilic.
• the functional group can be any group capable of causing a chemical reaction among the molecules to form chemical linkages. That is, the reaction mode of forming link ages among molecules by a condensation reaction or addition reaction, or crosslinkings by a polymerization reaction through heat and/or light can be utilized.
• incorporation of at least one functional group selected from the group consisting of the hardenable functional groups in Resin A is carried out by a method comprising introducing a low molecular, hardenable functional group-containing compound into a polymer containing functional groups represented by General Formula (I) or (II) by polymer reaction, or a method comprising copolymerizing at least one monomer corresponding to the copolymeric component containing at least one of the functional groups with a monomer corresponding to the repeating unit represented by General Formula (I) or (II) (monomer synthesis).
• the former polymer reaction can be carried out by any of known methods, for example, Nippon Kagakukai Edition, Shin-Jikken Kagakukoza, Vol. 14, "Synthesis and Reaction of Organic Compounds (I) to (V) (Yuki Kagobutsu no Gosei to Hanno)" published by Maruzen KK, 1978, and Yoshio Iwakura and Keisuke Kurita “Reactive Polymers (Hannosei Kobunshi)” published by Kohdansha (1977).
• Resin B is a hardenable resin causing a crosslinking reaction by heat and/or light, preferably causing a crosslinking reaction with the functional group described above in Resin A, and includes any of resins containing "heat and/or light-hardenable functional groups (sometimes referred to as hardenable functional groups in brief)" which will hereinafter be illustrated. As illustrated above, these hardenable functional groups may be contained in Resin A.
• heat-hardenable functional group of the hardenable functional groups of the present invention there can be used functional groups, for example, cited in the literatures described above to exemplify the polymerizable double bond groups.
• R 1 represents a hydrocarbon group, e.g., optionally substituted alkyl group containing 1 to 10 carbon atoms, such as methyl, ethyl, propyl, butyl, hexyl, octyl, decyl, 2-chloroethyl, 2-methoxyethyl, 2-cyanoethyl, etc., optionally substituted cycloalkyl group containing 4 to 8 carbon atoms, such as cycloheptyl, cyclohexyl, etc., optionally substituted aralkyl group containing 7 to 12 carbon atoms, such as benzyl, phenethyl, 3-phenylpropyl, chlorobenzyl, methylbenzyl, methoxybenzyl group, etc., and optionally substituted ary
• Group B capable of bonding with the functional group having dissociable hydrogen
• R 2 represents hydrogen atom or an alkyl group having 1 to 8 carbon atoms, such as methyl, ethyl, propyl, butyl, hexyl, octyl group, etc.
• as and a4 each represent hydrogen atoms, halogen atoms such as chlorine, bromine atom, etc., or alkyl groups containing 1 to 4 carbon atoms, such as methyl, ethyl group, etc.
• a crosslinked structure can be formed by chemical bonding of the functional groups, Groups A and B, for example, selected so as to combine at least one member respectively selected from Groups A and B shown in the following Table 1:
• the crosslinking reaction can be carried out by a polymerizable reaction using polymerizable double bond groups, exemplified above as the polymerizable functional groups.
• the monomer containing "the heat and/or light hadenable functional group” there can be used any of monomers containing hardenable functional groups in the substituents, which are copolymerizable with the monomer corresponding to the foregoing "copolymeric component represented by General Formula (III)".
• (meth)acrylic copolymers containing at least 30% by weight, based an the total amount of the copolymer, of a monomer represented by the following General Formula (IV) as a copolymeric constituent, exemplified as Resin B.
• U is hydrogen atom, a halogen atom such as chlorine or bromine atom, cyano group, an alkyl group containing 1 to 4 carbon atoms
• R 8 is an alkyl group containing 1 to 18 carbon atoms, which can be substituted, such as methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl, decyl, dodecyl, tridecyl, tetradecyl, 2-methoxyethyl or 2-ethoxyethyl group, an alkenyl group containing 2 to 18 carbon atoms, which can be substituted, such as vinyl, allyl, isopropenyl, butenyl, hexenyl, heptenyl or octenyl group, an aralkyl group containing 7 to 12 carbon atoms, which can be substituted, such as benzyl, phenethyl, methoxybenz
• the content of "copolymeric components containing crosslinking (hardenable) functional groups” is preferably 0.5 to 40%.
• the weight average molecular weight of Resin B is preferably 1 x 1 03 to 1 x10 5 , more preferably 5 ⁇ 10 3 to 5x10 4 .
• the ratio of Resin A and Resin B, used in the present invention, depending on the kind, grain diameter and surface state of inorganic photoconductive materials used therewith, is generally 40-99 of the former to 1-60 of the latter (by weight), preferably 50-95 to 5-50.
• crosslinking agent in the present invention there can be used compounds commonly used as crosslinking agents, for example, described in Shinzo Yamashita and Tosuke Kaneko "Handbook of Crosslinking Agents (Kakyozai Handbook)” published by Taiseisha (1981) and Kobunshi Gakkai Edition "High Molecular Data Handbook -Basis- (Kobunshi Data Handbook -Kisohen-)” published by Baihunkan (1986).
• crosslinking agent examples include organosilane compounds such as vinyltrimethoxysilane, vinyl- tributoxysilane, y-glycidoxypropyltrimethoxysilane, y-mercaptorpropyltriethoxysilane, ⁇ -aminopropyltriethoxysilane and other silane coupling agents; polyisocyanate compounds such as tolylene diisocyanate, o-tolylene diisocyanate, diphenylmethane diisocyanate, triphenylmethane triisocyanate, poly- methylenepolyphenyl isocyanate, hexamethylene diisocyanate, isophorone diisocyanate, high molecular polyisocyanates; polyol compounds such as 1,4-butanediol, polyoxypropylene glycol, polyoxyalkylene glycol, 1,1,1-trimethylolpropane and the like; polyamine compounds such as ethylenediamine,
• the quantity of the crosslinking agent used in the present invention is generally 0.5 to 30% by weight, preferably 1 to 10% by weight based on the resin used in the surface layer.
• the resin of the present invention and the known resin can be mixed in optional proportions, but it is preferable to adjust the mixing proportion so that the content of the hydrophilic group-forming functional group-containing resin be 1 to 100% by weight, preferably 5 to 70% by weight based on the whole resin, since if less than 1% by weight, the resulting lithographic printing plate precursor meets with a problem that the hydrophilic property obtained by the oil-desensitization treatment with an oil-desensitizing solution or dampening water to result in background stains during printing.
• the organic compound there can be used any of known compounds, specifically the following two kinds of compounds known as for an electrophotographic lithographic printing plate precursor.
• the first class has a photoconductive layer comprising an organic photoconductive compound, sensi tizing dye and binder resin, as predominant components, as disclosed in Japanese Patent Publication Nos. 17162/1962 and 51462/1987, and Japanese Patent Laid-Open Publication Nos. 2437/1977, 19802/1979, 107246/1981 and 161863/1982 and the second class has a photoconductive layer comprising a charge generating agent, charge transporting agent and binder resin, as predominant components, as disclosed in Japanese Patent Laid-Open Publication Nos.
• sensitizing dye contained in the photoconductive layer there can be used the commonly used sensitizing dyes for electrophotographic photoreceptors described in "Denshi Shashin (Electrophotography)” 12 9 (1973), and “Yuki Gosei Kagaku (Organic Synthetic Chemistry)” 24 (11), 1010 (1966).
• Preferable examples thereof are pyrylium dyes as described in US Patent Nos. 3;141,770 and 4,283,475, Japanese Patent Publication No. 25658/1973 and Japanese Patent Laid-Open Publication No. 71965/1987, triarylmethane dyes as described in "Applied Optics Supplement” 3 , 50 (1969) and Japanese Patent Laid-Open Publication No.
• polymethine dyes capable of spectrally sensitizing near infrared radiations to infrared radiations with longer wavelengths of at least 700 nm are described in Japanese Patent Publication No. 41061/1976; Japanese Patent Laid-Open Publication Nos. 840/1972, 44180/1972, 5034/1974, 45122/1974, 46245/1982, 35141/1981, 157254/1982, 26044/1986 and 27551/1986; U.S. Patent Nos. 3,619,154 and 4,175,956; and "Research Disclosure" 216, pages 117-118 (1982).
• additives which have hitherto been used for electrophotographic photoreceptors.
• additives include chemical sensitizers to improve the electrophotographic sensitivity, various plasticizers to improve the film property, surfactants, etc.
• the quantity of the various additives is not particularly limited, but is generally in the range of 0.001 to 2.0 parts by weight per 100 parts by weight of the photoconductor.
• the photoconductive layer of the present invention can be provided on a support as well known in the art.
• a support for an electrophoto graphic light-sensitive layer is preferably electroconductive and as the electroconductive support, there can be used, as known in the art, substrates such as metals, papers, plastic sheets, etc.
• Production of a lithographic printing plate using the electrophotographic lithographic printing plate precursor of the present invention can be carried out in known manner by forming a copying image thereon and then subjecting the non-image area to an oil-desensitization processing according to the present invention.
• the oil-desensitization of the resin of the present invention, containing the functional groups represented by General Formula (I) can be accomplished by processing with a solution containing a compound having hydrophilic groups capable of readily undergoing nucleophilic reaction with the double bonds in water or a water-soluble organic solvent.
• the hydrophilic compound causing a nucleophilic substitution reaction with the double bond of the functional group represented by General Formula (I) includes a hydrophilic compound containing a substituent having a nucleophilic constant n of at least 5.5 (Cf. R.G. Pearson, H. Sobel and J. Songstad "J. Amer. Chem.
• sulfinic acid examples include 2-hydroxyethylsulfinic acid, 3-hydroxypropanesulfinic acid, 4-hydrox- ybutanesulfinic acid, carboxybenzenesulfinic acid, dicarboxybenzenesulfinic acid and the like.
• Examples of the primary or secondary amine compound are N-(2-hydroxyethyl)amine, N,N-di(2-hydroxyethyl)amine, N,N-di(2-hydroxyethyl)ethylenediamine, tri(2-hydroxyethyl)ethylenediamine, N-(2,3-dihydroxypropyl)amine, N,N-di(2,3-dihydroxypropyl)amine, 2-aminopropionic acid, aminobenzoic acid, aminopyridine, aminobenzenedicarboxylic acid, 2-hydroxyethylmorpholine, 2-carboxyethylmorpholine, 3-carboxypiperidine and the like.
• the nucleophilic compounds are used in such a manner that each of them is contained in the foregoing oil-desensitization processing solution of a photoconductor or in the foregoing processing solution of the binder resin.
• the processing solution has a pH of at least 8.
• the oil-desensitization can be carried out with the processing solution containing the nucleophilic compound.
• a mixed solution of 92 g of a monomer M-3 having the following structure, 8 g of 2,3-dihydroxypropyl methacrylate and 200 g of toluene was heated at a temperature of 75°C under a nitrogen stream. While stirring, 1.0 g of A.I.B.N. was added thereto, followed by reacting for 3 hours, thus obtaining the polymer A-3 with an M w of 5.0 ⁇ 10 4 .
• a mixed solution of 85 g of the monomer M-4, 10 g of 2-hydroxyethyl methacrylate, 5 g of acrylic acid and 200 g of toluene was heated at a temperature of 90 °C under a nitrogen stream, to which 6 g of A.I.B.N.was added, followed by reacting for 4 hours.
• the thus resulting polymer A-6 had an (M w) of 8.5x103.
• a mixed solution of 78 g of a monomer M-5 having the following structure, 20 g of allyl methacrylate, 2 g of 2-(2-carboxyethylcarbonyloxy)ethyl methacrylate and 300 g of toluene was heated at a temperature of 60°C under a nitrogen stream, to which 1.5 g of A.B.V.N. was added, followed by reacting for 4 hours and 0.5 g of A.B.V.N was further added, followed by reacting for 3 hours.
• the thus resulting polymer A-7 had an (M w) of 6.8 ⁇ 10 4 .
• a mixed solution of 95 g of the monomer M-5, 5 g of methacrylic acid, 3 g of divinylbenzene, 1.5 g of n-dodecyl mercaptan and 200 g of toluene was heated at 75 0 C under a nitrogen stream. 1 g of A.I.B.N. was added thereto, followed by reacting for 4 hours, 0.5 g of A.I.B.N. was further added, followed by reacting for 3 hours and 0.5 g of A.I.B.N. was further added, followed by reacting for 3 hours.
• the thus resulting polymer A-8 had an (M w) of 7.5x10 3 .
• a mixed solution of 63.5 g of benzyl methacrylate, 35 g of the monomer (M-1), 1.5 g of acrylic acid and 200 g of toluene was heated at a temperature of 75° C under a nitrogen stream. While stirring, 1.0 g of A.I.B.N. was added thereto, followed by reacting for 4 hours, and 0.4 g of A.I.B.N. was further added, followed by reacting for 3 hours.
• the thus resulting polymer A-10 had a weight average molecular weight (M w) of 4.3 ⁇ 10 4 .
• a mixed solution of 52 g of phenyl methacrylate, 10 g of 2-hydroxyethyl methacrylate, 30 g of the monomer M-2, 2.0 g of acrylic acid and 200 g of toluene was heated at a temperature of 70 °C under a nitrogen stream. While stirring, 1.5 g of A.I.B.N. was added thereto, followed by reacting for 5 hours and 0.5 g of A.I.B.N. was further added, followed by reacting for 3 hours. The thus resulting polymer A-11 had a (M w) of 3.5 ⁇ 10 4 .
• a mixed solution of 64.5 g of 2-chlorophenyl methacrylate, 34 g of a monomer M-6 having the following structure, 1.5 g of methacrylic acid and 200 g of toluene was heated at a temperature of 75 °C under a nitrogen stream. While stirring, 1.0 g of A.I.B.N. was added thereto, followed by reacting for 4 hours and 0.4 g of A.I.B.N. was further added, followed by reacting for 3 hours. After cooling to room temperature, 15 g of triethylamine was added to the resulting reaction mixture and stirred at room temperature for 1 hour.
• the precipitated triethylamine hydrochloride was separated by filtration and reprecipitated in 2000 ml of methanol.
• the precipitated white crystals was collected by filtering and dried under reduced pressure at room temperature, thus obtaining the polymer A-12 with a yield of 75 g and an (M w) of 4.5 ⁇ 10 4 .
• a mixed solution of 15 g of 2-hydroxyethyl methacrylate, 80 g of the monomer M-4, 2.0 g of divinylbenzene and 200 g of toluene was heated at a temperature of 70°C under a nitrogen stream. While stirring, 1.5 g of azobis(isovaleronitrile) (hereinafter referred to as A.B.V.N.) was added thereto, followed by reacting for 4 hours and 0.5 g of A.B.V.N. was further added, followed by reacting for 3 hours.
• the thus resulting polymer A-13 had an (M w) of 1.5x10 5 .
• a mixed solution of 95 g of the monomer M-5, 5 g of methacrylic acid, 3 g of divinylbenzene, 1.5 g of n-dodecyl mercaptan and 200 g of toluene was heated at 75 0 C under a nitrogen stream. 1 g of A.I.B.N. was added thereto, followed by reacting for 4 hours, 0.5 g of A.I.B.N. was further added, followed by reacting for 3 hours and 0.5 g of A.I.B.N. was further added, followed by reacting for 3 hours. After cooling, 20 g of triethylamine was added and stirred at a temperature of 30 C for 1 hour.
• Synthetic Example 7 of Resin A was repeated except changing the copolymeric components as shown in Table 2 to synthesize copolymers having the following structures as shown in Table 2.
• the resulting polymers A-15 to A-23 each had an (M w) of 4 ⁇ 10 4 to 6 ⁇ 10 4 .
• a solution of 5% by weight (as solid content) of Resin A-2 and 0.5% by weight of 1,3-xylylene diisocyanate in toluene was coated onto the surface of this electrophotographic photoreceptor by a doctor blade and heated at 110° C for 2 hours to form a surface layer having a thickness of about 2 ⁇ m.
• the resulting photosensitive material was subjected to oil-desensitization by immersing for 30 seconds in an oil-desensitizing solution (E-1) prepared by the following recipe:
• the above-prepared lithographic printing plate precursor was processed by an automatic printing plate making machine ("'ELP 404V” manufactured by Fuji Photo Film Co., Ltd.) using a negatively chargeable liquid developer to form a toner image thereon.
• the precursor was then subjected to oil-desensitization under the same conditions as described above.
• the resulting printing plate (offset master plate) was mounted on an offset printing machine ("Hamada Star 800SX” manufactured by Hamada Star K.K.), and printing on fine paper was carried out.
• the number of prints that could be obtained with no problem of image quality and background stain formation on the non-image areas was 10,000.
• a solution containing 5% by weight (as solid content) of Resin A-4 and 0.6% by weight of 1,6-hexane diisocyanate in toluene was coated on the resulting photoreceptor by a doctor blade to form a surface layer with a thickness of about 2 u.m on the photosensitive layer.
• a paper analyzer Paper Analyzer SP-428 - commercial name- manufactured by Kawaguchi Denki KK
• the light-sensitive material was processed by an automatic plate making machine (ELP 404V -commercial name- manufactured by Fuji Photo Film Co., Ltd.) using a toner (ELP-T -commercial name- manufactured by Fuji Photo Film Co., Ltd.) in the same manner as in Example 1.
• the resulting master plate for offset printing had a clear image having a density of at least 1.0.
• the plate was subjected to oil-desensitization by immersing for 30 seconds in an oil-desensitizing solution (E-2) prepared by the following recipe, followed by washing with water: These components were dissolved in distilled water to 1000 ml and the pH of the solution was adjusted to 12.0 with sodium hydroxide. The non-image area was sufficiently rendered hydrophilic as represented by a contact angle with distilled water of less than 10°.
• E-2 oil-desensitizing solution
• the print obtaining 10000 prints had a clear image and no fog on the non-image area.
• a mixture of 45 g of a copolymer of methyl methacrylate, ethyl methacrylate and acrylic acid (39/60/1 weight ratio) having a weight average molecular weight of 42000, 200 g of zinc oxide, 0.03 g of Rose Bengal, 0.02 g of tetrabromophenol, 0.20 g of phthalic anhydride and 300 g of toluene was dispersed in a ball mill for 2 hours to prepare a light-sensitive layer-forming composition, which was then applied to a paper rendered electrically conductive to give a dry coverage of 25 g/m 2 by a wire bar coater, followed by drying at 100 C for 1 minute.
• a solution containing 5% by weight of Resin A-6 and 0.75% by weight of 1,4-xylylene diisocyanate in toluene was coated on the resulting photoreceptor by a doctor blade and heated at 90 C for 2 hours to form a surface layer with a thickness of about 2 ⁇ m on the light-sensitive layer.
• the thus coated paper was allowed to stand in a dark place at 20° C and 65% RH for 24 hours to prepare an electrophotographic light-sensitive material.
• This light-sensitive material was negatively charged at -6 kV and then subjected to evaluation of the electrostatic characteristics, thus obtaining an initial potential (V o ) of -550 V, dark charge retention (D.R.R.) of 88% and half decay exposure (E 1/10 ) of 11.0 (lux ⁇ sec).
• the light-sensitive material was subjected to plate making in an analogous manner to Example 1 and the resulting master plate for offset printing had a clear image having a density of at least 1.0.
• the plate was subjected to oil-desensitization by immersing for 30 seconds in the oil-desensitizing solution (E-1) used in Example 1 and washed with water.
• the non-image area of the resulting plate was sufficiently rendered hydrophilic as represented by a contact angle with distilled water of less than 10°.
• the print obtaining 10000 prints had a clear image and no fog on the non-image area.
• Example 3 was repeated except using copolymer resin (Resins A-24 to A-35 shown in Table 3) of the present invention instead of Resin A-2 of the present invention, thus obtaining electrophotographic light-sensitive materials, each Resin A having an M w of 3 ⁇ 10 4 to 5 ⁇ 10 4 .
• the resulting master plate had a density of at least 1.0 and clear image.
• the resulting master plate had a density of at least 1.0 and clear image.
• Example 3 was repeated except using copolymers shown in Table 4 instead of Resin A-6 and 1,4-xylylene diisocyanate to be coated as the surface layer of the photoreceptor, thus obtaining electrophotographic light-sensitive materials, each having an (M w) in the range of 3 ⁇ 10 4 to 5 ⁇ 10 4 .
• the resulting master plate had a density of at least 1.0 and clear image.
• the resulting master plate had a density of at least 1.0 and clear image.
• a solution of 5% by weight (as solid content) of Resin A-7, 0.8% by weight of ethylene glycol dimethacrylate and 0.05% by weight of 1,1-azobis(cyclohexane-1-carbonitrile) in toluene was coated on the resulting photoreceptor by a doctor blade and heated at 100°C for 3 hours to form a surface layer of about 2 ⁇ m thick. Then, the light-sensitive material was allowed to stand in a dark place at 20 C and 65% RH to prepare an electrophotographic light-sensitive material.
• the light-sensitive material was then subjected to evaluation of the electrostatic characteristics, image quality and printing property to thus obtain the following results:
• the light-sensitive material was excellent in the electrostatic characteristics, dark charge retention and photosensitivity and gave a clear image without occurrence of the background fog and disappearance of fine lines even under severer conditions, e.g. high temperature and high humidity (30 C, 80% RH).
• the plate thus oil-desensitized was subjected to printing in an analogous manner to Example 1 so as to examine the printing durability.
• the light-sensitive material of the present invention exhibited excellent electrostatic characteristics and printing property.
• a mixture of 10 g (as solid content) of Resin A-8, 10 g of zinc oxide and 100 g of toluene was dispersed in a ball mill for 2 hours, to which 2 g of ethylene glycol glycidyl ether was further added, and the mixture was then dispersed in the ball mill for 10 minutes to prepare a dispersion, which was applied to the surface of the resulting photoreceptor by a wire bar coater and heated at 110°C for 2 hours to form a surface layer of about 2.5 ⁇ m thick.
• the thus coated paper was allowed to stand in a dark place at 20°C and 65% RH for 24 hours to prepare an electrophotographic light-sensitive material.
• the light-sensitive material was then subjected to evaluation of the electrostatic characteristics and image quality in an analogous manner to Example 27 to thus obtain the following results:
• the light-sensitive material of the present invention exhibited very excellent properties.
• Master plates for offset printing were prepared by using the light-sensitive materials prepared in Examples 1 to 27 and carrying out an etching treatment as follows:
• the each material was sufficiently rendered hydrophilic as represented by a contact angle with water of less than 10°.
• the print obtaining 10000 prints had a clear image and no fog on the non-image area.
• the electrophotographic photosensitive material obtained in Example 28 but before coating the surface layer was coated with toluene solution containing 5% by weight of each of Resin A shown in the following Table 6 by a doctor blade and heated at 100°C for 30 seconds to form a surface layer with a thickness of about 2 ⁇ m.
• Each of the light-sensitive materials was irradiated by a high voltage mercury lamp of 400 W at an interval of 30 cm and then allowed to stand in a dark place for 24 hours under conditions of 20 C and 65% RH to prepare a master plate for lithographic printing.
• Example 1 The procedure of Example 1 was repeated except using Resin A-6 and 1% by weight of Resin B-1 having the following structure for forming the surface layer instead of Resin A-2 and 0.5% by weight of 1,3-xylene diisocyanate, thus obtaining the similar results thereto.
• Example 2 The procedure of Example 2 was repeated except using, for forming the surface layer, 5% by weight of Resin A-13, 1% by weight of Resin B-2 having the following structure and 0.6% by weight of 1,3-xylylene diisocyanate instead of 5% by weight of Resin A-4 and 0.6% by weight of 1,6-hexane diisocyanate, and for oil-desensitizing, an oil-desensitizing processing solution (E-5) prepared by the following recipe instead of Oil-desensitizing Processing Solution E-2:
• Example 3 The procedure of Example 3 was repeated except using, for forming the surface layer, 5% by weight of Resin A-7, 0.8% by weight of Resin B-3 having the following structure and 0.02% by weight of 2,2'-azobisisobutyronitrile instead of 5% by weight of Resin A-6 and 0.75% by weight of 1,4-xylylene diisocyanate used in Example 3:
• Example 45 was repeated except using compounds shown in the following Table 5 instead of Resin A-7, Resin B-3 and the azobis compound, coated as the surface layer of the photoreceptor in Example 45, thus obtaining electrophotographic light-sensitive materials.
• the crosslinking compounds were used in the predetermined amounts shown in Table 5 and the others were used in the same amounts as described in Example 45.
• a solution of 5% by weight (as solid content) of Resin A-15, 1 % by weight of Resin B-3 and 0.05% by weight of 1,4-tetramethylenediamine in toluene was coated on the resulting photoreceptor by a doctor blade and heated at 100 °C for 30 seconds and at 120 °C for 1 hour to form a surface layer of about 2 ⁇ m thick. Then, the light-sensitive material was allowed to stand in a dark place at 20° C and 65% RH to prepare an electrophotographic light-sensitive material.
• the light-sensitive material was then subjected to evaluation of the electrostatic characteristics, image quality and printing property to thus obtain the following results:
• a mixture of 6.0 g of Resin R-3, 34 g of Resin R-4, 200 g of zinc oxide, 0.018 g of the cyanine dye (II), 0.20 g of maleic anhydride and 300 g of toluene was dispersed in a ball mill for 3 hours to prepare a light-sensitive layer-forming composition, which was then applied to a paper rendered electrically conductive to give a dry coverage of 25 g/m 2 by means of a wire bar coater, followed by drying at 110°C for 30 seconds. The thus coated paper was allowed to stand in a dark place at 20°C and 65% RH for 24 hours to prepare an electrophotographic light-sensitive material.
• a mixture of 10 g (as solid content) of Resin A-7, 1.5 g of Resin B-3, 10 g.of zinc oxide and 100 g of toluene was dispersed in a ball mill for 2 hours, to which 1 g of ethylene glycol glycidyl ether was further added, and the mixture was then dispersed in the ball mill for 10 minutes to prepare a dispersion, which was applied to the surface of the resulting photoreceptor by a wire bar coater and heated at 110°C for 2 hours to form a surface layer of about 2.5 ⁇ m thick.
• the thus coated paper was allowed to stand in a dark place at 20 C and 65% RH for 24 hours to prepare an electrophotographic light-sensitive material.
• the light-sensitive material subjected to plate making was immersed in an oil-desensitizing processing solution (E-4), prepared by the following recipe, for 20 seconds and washed with water.
• E-4 oil-desensitizing processing solution
• the non-image area was sufficiently rendered hydrophilic as represented by a contact angle with water of less than 10°.
• the print obtaining 10000 prints had a good image quality.
• the light-sensitive material of the present invention exhibited very excellent properties.
• Master plates for offset printing were prepared by using the light-sensitive materials prepared in Examples 43 to 65 and carrying out an etching treatment as follows:
• Each of the light-sensitive materials was immersed and etched in the solution ELP-E diluted by 2 times with distilled water for 20 seconds and then immersed in the above described processing solution at 25°C for 1 minute.
• the each material was sufficiently rendered hydrophilic as represented by a contact angle with water of less than 10°.
• the print obtaining 10000 prints had a clear image and no fog on the non-image area.
• the light-sensitive material was subjected to plate making in an analogous manner to Example 64 and the resulting master plate for offset printing had a clear image having a density of at least 1.2.
• an electrophotographic lithographic printing plate precursor which does not deteriorate during long storage under severer conditions and which has excellent electrostatic characteristics as well as good printing properties.

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