Electrophotographic lithographic printing plate precursor

A lithographic printing plate precursor excellent in oil-desensitivity, whereby an original is faithfully reproduced without occurrence of overall or spotted stains as an offset master is provided, which comprises an electrically conductive support and at least one photoconductive layer, provided thereon, containing photoconductive zinc oxide and a binder resin, in which said photoconductive layer contains hydrophilic resin grains having an average grain diameter of same as or smaller than the maximum grain diameter of said photoconductive zinc oxide grains.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to an electrophotographic lithographic printing 
plate precursor made by an electrophotographic system and more 
particularly, it is concerned with an improvement in a photoconductive 
layer forming composition for the lithographic printing plate precursor. 
2. Description of the Prior Art 
A number of offset masters for directly producing printing plates have 
hitherto been proposed and some of them have already been put into 
practical use. Widely employed among them is a system in which a 
photoreceptor comprising a conductive support having provided thereon a 
photoconductive layer mainly comprising photoconductive particles, for 
example, of zinc oxide and a resin binder is subjected to an ordinary 
elecrophotographic processing to form a highly lipophilic toner image on 
the surface of the photoreceptor, followed by treating the surface with an 
oil-desensitizing solution referred to as an etching solution to 
selectively render non-image areas hydrophilic and thus obtain an offset 
printing plate. 
Requirements of offset masters for obtaining satisfactory prints include: 
(1) an original should be reproduced faithfully on the photoreceptor; (2) 
the surface of the photoreceptor has affinity with an oil-desensitizing 
solution so as to render non-image areas sufficiently hydrophilic, but, at 
the same time, has resistance to solubilization; and (3) 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 retain 
the hydrophilic properties sufficiently to be free from stains even upon 
printing a large number of prints. 
It is known that these properties are affected by the ratio of zinc oxide 
to a resin binder in the photoconductive layer. For example, if the ratio 
of a binder resin to zinc oxide particles is decreased, oil-desensitivity 
of the surface of the photoconductive layer is increased to reduce 
background stains, but, on the other hand, the internal cohesion of the 
photoconductive layer per se is weakened, resulting in reduction of 
printing durability due to insufficient mechanical strength. If the ratio 
of a binder resin to zinc oxide particles is increased, on the other hand, 
printing durability is improved, but background staining becomes 
conspicuous. It is a matter of course that the background staining is a 
phenomenon associated with the degree of oil-desensitization achieved and 
it has been made apparent that the oil-desensitization of the 
photoconductive layer surface depends on not only the binder resin/zinc 
oxide ratio in the photoconductive layer, but also the kind of the binder 
resin used to a great extent. 
For particular use as an offset master, occurrence of background stains due 
to insufficient oil-desensitivity presents a serious problem. In order to 
solve this problem, various resins for binding zinc oxide have been 
proposed, including resins of Mw 1.8-10.times.10.sup.-4 and Tg 
10.degree.-80.degree. C. obtained by copolymerizing (meth)acrylate 
monomers and other monomers in the presence of fumaric acid in combination 
with copolymers of (meth)acrylate monomers and other monomers than fumaric 
acid, as disclosed in Japanese Patent Publication No. 31011/1975; 
terpolymers each containing a (meth)acrylic acid ester unit having a 
substituent having carboxylic acid group at least 7 atoms distant from the 
ester linkage, as disclosed in Japanese Patent Laid-Open Publication No. 
54027/1978; tetra- or pentamers each containing an acrylic acid unit and 
hydroxyethyl (meth)acrylate unit, as disclosed in Japanese Patent 
Laid-Open Publication Nos. 20735/1979 and 202544/1982; terpolymers each 
containing a (meth)acrylic acid ester unit having an alkyl group having 6 
to 12 carbon atoms as a substituent and a vinyl monomer containing 
carboxylic acid group, as disclosed in Japanese Patent Laid-Open 
Publication No. 68046/1983; and the like. These resins function to improve 
the oil-desensitivity of photoconductive layers. 
Nevertheless, evaluation of such resins as noted above for improving the 
oil-desensitization indicate that none of them is completely satisfactory 
in terms of stain resistance, printing durability and the like. 
Furthermore, it has hitherto been studied to use resins having functional 
groups capable of forming hydrophilic groups through decomposition as such 
a binder resin, for example, those having functional groups capable of 
forming hydroxyl groups as disclosed in Japanese Patent Laid-Open 
Publication Nos. 195684/1987, 210475/1987 and 210476/1987 and those having 
functional groups capable of forming carboxyl groups as disclosed in 
Japanese Patent Laid-Open Publication No. 212669/1987. 
These resins are those which form hydrophilic groups through hydrolysis or 
hydrogenolysis with an oil-desensitizing solution or dampening water used 
during printing. When using them as a binder resin for a lithographic 
printing plate precursor, it is possible to avoid various problems, e.g., 
deterioration of smoothness, deterioration of electrophotographic 
properties such as dark charge retention and photosensitivity, etc., which 
are considered to be caused by strong interaction of the hydrophilic 
groups and surfaces of photoconductive zinc oxide particles in the case of 
using resins intrinsically having hydrophilic groups per se, and at the 
same time, a number of prints with clear image quality and without 
background stains can be obtained, since the hydrophilic property of 
non-image areas rendered hydrophilic with an oil-desensitizing solution if 
further increased by the above described hydrophilic groups formed through 
decomposition in the resin to make clear the lipophilic property of image 
areas and the hydrophilic property of non-image areas and to prevent the 
non-image areas from adhesion of a printing ink during printing. 
At the present time, in the electrophotographic lithographic printing, a 
higher efficiency has been required and in particular, it has been 
required to increase the speeds of plate making and etching and to obtain 
a print with a clear image quality, particularly free from background 
stains, from the start of printing, thus reducing loss of prints. 
For such requirements is insufficient the above proposed offset printing 
plate using the binder resin capable of forming hydrophilic groups through 
decomposition with respect to the problems of increasing the etching speed 
and reducing the loss of prints. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide an electrophotographic 
lithographic printing plate precursor, whereby the disadvantages of the 
prior art, as described above, can be overcome. 
It is another object of the present invention to provide a lithographic 
printing plate precursor excellent in oil-desensitivity, whereby an 
original is faithfully reproduced without occurrence of overall or spotted 
stains as an offset master. 
It is a further object of the present invention to provide a lithographic 
printing plate with a high printing durability, in which the hydrophilic 
property of non-image areas is sufficiently held to prevent occurrence of 
background stains even if the steps of from etching to printing are 
speeded up. 
These objects can be attained by an electrophotographic lithographic 
printing plate precursor comprising a conductive support and at least one 
photoconductive layer, provided thereon, containing photoconductive zinc 
oxide and a binder resin, wherein said photoconductive layer contains 
hydrophilic resin grains having an average grain diameter of same as or 
smaller than the maximum grain diameter of said photoconductive zinc oxide 
grains.

DETAILED DESCRIPTION OF THE INVENTION 
The hydrophilic resin used in the present invention includes resins such as 
having a higher order network structure and such that the grain has the 
above described average grain diameter and the film formed by dissolving 
the resin grains in a suitable solvent and then coating has a contact 
angle with distilled water of 50 degrees or less, preferably 30 degrees or 
less, measured by a goniometer. 
In the present invention, it is important that the hydrophilic resin is 
dispersed in the photoconductive layer in the form of grains whose average 
grain diameter is same as or smaller than the maximum grain diameter of 
the photoconductive zinc oxide grains. Such hydrophilic resin grains have 
such smaller specific areas and less interaction with zinc oxide grain 
surfaces than those present under molecular state that a lithographic 
printing plate can be given capable of exhibiting good printing properties 
because of less deterioration of electrophotographic properties. If there 
are resin grains having larger grain diameters than zinc oxide grains, the 
electrophotographic properties are deteriorated and in particular, uniform 
electrification cannot be obtained, thus resulting in density unevenness 
in an image area, disappearance of letters or fine lines and background 
staining in a non-image area in a reproduced image. 
Specifically, the resin grains of the present invention have a maximum 
grain diameter of at most 10 .mu.m, preferably at most 5 .mu.m and an 
average grain diameter of at most 1.0 .mu.m, preferably at most 0.5 .mu.m. 
The specific surface areas of the hydrophilic resin grains are increased 
with the decrease of the grain diameter, resulting in good 
electrophotographic properties, and the grain size of colloidal grains, 
i.e., about 0.01 .mu.m or smaller is sufficient. However, very small 
grains cause the similar troubles to those in the case of molecular 
dispersion and accordingly a grain size of 0.001 .mu.m or larger is 
preferable. On the other hand, zinc oxide has generally a grain diameter 
of 0.05 to 10 .mu.m, preferably 0.1 to 5 .mu.m. 
In the present invention, the hydrophilic resin grains or particles are 
preferably used in a proportion of 0.1 to 5% by weight to 100 parts by 
weight of photoconductive zinc oxide, since if the hydrophilic resin 
grains are less than 0.1% by weight, the hydrophilic property of a 
non-image area does not become sufficient, while if more than 5% by 
weight, the hydrophilic property of a non-image area is further improved, 
but electrophotographic properties and reproduced images are deteriorated. 
As the hydrophilic resin of the present invention, optionally having a 
higher order network structure, there can favorably be used any of 
synthetic and natural hydrophilic resins, for example, described in P. 
Molyneax "Water-Soluble Synthetic Polymers: Properties and Behavior" Vol. 
I and Vol. II, CRC Press Inc. (1982); C. A. Finch "Chemistry and 
Technology of Water-Soluble Polymers" Plenam Press (1983); Matao Nakamura 
"Water-Soluble Polymers [Suiyosei Kobunshi)" Kagaku Kogyo-sha (1973); 
Kaimen Kagaku Kenkyukai "New Processing and Modifying Technique and 
Development of Uses of Water-Soluble Polymers Aqueous Dispersion Type 
Resins" Keiei Kaihatsu Center Shuppan-bu (1982) and Davidson 
"Water-Soluble Resin" Reinhold (1968). 
The synthetic hydrophilic resins include those containing, in the molecular 
structures, at least one hydrophilic group selected from the group 
consisting of ether group, ethylene oxide group, --OH, --SH, --COOH, 
--SO.sub.2 H, --SO.sub.3 H, --PO.sub.3 H.sub.2, --CN, --CONH.sub.2, --CHO, 
--SO.sub.2 R.sub.1, 
##STR1## 
4- to 6-membered heterocyclic ring optionally containing at least one 
nitrogen atom and organosilane group. 
In the above described hydrophilic groups, R.sub.1 is a hydrocarbon group 
containing 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms, which can 
be substituted, for example, methyl, ethyl, propyl, butyl, 2-chloroethyl, 
2-bromoethyl, 2-fluoroethyl, 3-chloropropyl, 3-methoxypropyl, 
2-methoxybutyl, benzyl, phenyl, propenyl, methoxymethyl, ethoxymethyl and 
2-methoxyethyl groups. 
R.sub.2 is an aliphatic group containing 1 to 6 carbon atoms, preferably 1 
to 4 carbon atoms, which can be substituted, i.e., the similar group to 
R.sub.1 or --OR' wherein R' has the same meaning as R.sub.1. 
R.sub.3 and R.sub.4 being same or different represent hydrogen atoms or 
hydrocarbon groups containing 1 to 6 carbon atoms, preferably 1 to 4 
carbon atoms, which can be substituted, i.e., have the same meaning as 
R.sub.1. The sum of carbon atoms in R.sub.3 and R.sub.4 are at most 8, 
preferably at most 6. 
R.sub.5, R.sub.6 and R.sub.7 have the same meanings as R.sub.3 and R.sub.4, 
which can be same or different. 
X.sup..crclbar. is an anion, for example, halide ion such as chloride ion, 
bromide ion or iodide ion, perchlorate ion, tetrafluoroborate ion, 
hydroxide ion, carboxylate ion such as acetonate ion or propionate ion, 
sulfonate ion such as methanesulfonate ion, benzenesulfonate ion or 
p-toluenesulfonate ion, or the like. 
.gamma. is 1 or 2 and when .gamma.=1, R.sub.5 to R.sub.7 contain at least 
one acidic group such as --SO.sub.3 H, --PO.sub.3 H.sub.2 or --COOH as a 
substituent. A typical example is 
##STR2## 
Each of the above described groups, --COOH, --SO.sub.2 H, --SO.sub.3 H, 
--PO.sub.3 H.sub.2, and 
##STR3## 
can form a salt with an alkali metal such as lithium, sodium or potassium, 
alkaline earth metal such as calcium or magnesium, or other metals such as 
zinc and aluminum, or an organic base such as triethylamine, pyridine, 
morpholine or piperazine. 
Examples of the 4- to 6-membered heterocyclic ring optionally containing at 
least one nitrogen atom, as described above, are pyridine ring, piperidine 
ring, pyrrole ring, imidazole ring, pyrazine ring, pyrrolidine ring, 
pyrroline ring, imidazolidine ring, imidazoline ring, pyrazolidine ring, 
piperazine ring, morpholine ring, pyrrolidone ring, furan ring, pyrane 
ring, tetrahydrofuran ring, dioxane ring, dioxolane ring, oxazoline ring, 
1,3-oxazine-2-on ring, morpholine-di-on ring, morpholinone ring and the 
like. These heterocyclic rings can be substituted by substituents, 
illustrative of which are halogen atoms such as fluorine, chlorine and 
bromine atoms; hydrocarbon groups containing 1 to 8 carbon atoms, in 
particular, alkyl groups containing 1 to 3 carbon atoms, which can be 
substituted, such as methyl, ethyl, propyl, butyl, 2-chloroethyl, 
2-bromoethyl, 2-hydroxyethyl, 2-cyanoethyl, 2-methoxyethyl, 2-ethoxyethyl, 
2-butoxyethyl, 2-carboxyethyl, carboxymethyl, 3-sulfopropyl, 4-sulfobutyl, 
2-methoxycarbonylethyl, 2-ethoxycarbonylethyl, 2-methanesulfonylethyl, 
benzyl, carboxybenzyl, carboxymethylbenzyl, phenyl, carboxyphenyl, 
sulfophenyl, methanesulfonylphenyl, ethanesulfonylphenyl, 
carboxymethylphenyl, methoxyphenyl, chlorophenyl groups and the like; 
--OR" groups wherein R" represents the above described hydrocarbon groups 
containing 1 to 8 carbon atoms, which can be substituted and --COOR'" 
groups wherein R'" has the same meaning as R". 
The organosilane group includes, for example, a recurring unit represented 
by the following general formula (I): 
##STR4## 
wherein A is an alkyl group containing 1 to 4 carbon atoms, which can be 
substituted, such as methyl, ethyl, propyl, butyl, 2-chloroethyl, 
2-methoxyethyl, 2-cyanoethyl groups and the like; --OR"" group wherein R"" 
has the same meaning as A or --"Z" group wherein Z is trimethylsiloxy, 
pentamethyldisiloxanyl, heptamethyltrisiloxanyl, nonamethyltetrasiloxanyl, 
bis(trimethylsiloxy)methylsiloxanyl, tri(trimethylsiloxy) siloxanyl group 
or the like, and A.sub.1 is an alkyl group containing 1 to 6 carbon atoms, 
which can be substituted, such as methyl, ethyl, propyl, butyl, hexyl, 
2-methoxyethyl, 2-ethoxypropyl, 2-cyanoethyl, 2-hydroxyethyl, 
2-hydroxy-3-chloropropyl or 2-chloroethyl group, --OR'"" group wherein 
R'"" has the same meaning as R"" or a group such that an unsaturated bond 
selected from the group consisting of vinyl, methacryloxy, acryloxy, 
methacrylamide, acrylamide, styryl and allyl groups is polymerized and 
combined with another recurring unit through a divalent hydrocarbon group 
containing 1 to 6 carbon atoms, and a is an integer of 1 to 10, the sum of 
a being at least 2. 
The hydrophilic resin of the present invention is a homopolymer or 
copolymer comprising a polymeric component having at least one of the 
hydrophilic groups in the polymer side chain, the polymeric component 
being in a proportion of 20 to 100% by weight, preferably 30 to 100% by 
weight to the resin. 
More specifically, this hydrophilic group-containing polymeric component is 
represented, for example, by the following general formula (II): 
##STR5## 
In the general formula (II), X is --COO--, --OCO--, --O--, 
##STR6## 
wherein Z.sub.1 and Z.sub.2 each represent hydrogen atom or hydrocarbon 
groups containing 1 to 7 carbon atoms such as methyl, ethyl, propyl, 
butyl, 2-chloroethyl, 2-hydroxyethyl, 3-bromo-2-hydroxypropyl, 
2-carboxyethyl, 3-carboxypropyl, 4-carboxybutyl, 3-sulfopropyl, benzyl, 
sulfobenzyl, methoxybenzyl, carboxybenzyl, phenyl, sulfophenyl, 
carboxyphenyl, hydroxyphenyl, 2-methoxyethyl, 3-methoxypropyl, 
2-methanesulfonylethyl, 2-cyanoethyl, N,N-(dichloroethyl)aminobenzyl, 
N,N-(dihydroxyethyl)aminobenzyl, chlorobenzyl, methylbenzyl, 
N,N-(dihydroxyethyl)aminophenyl, methanesulfonylphenyl, cyanophenyl, 
dicyanophenyl, acetylphenyl groups and the like, Z.sub.3 and Z.sub.4 each 
represent, same or different, hydrogen atom, halogen atoms such as 
fluorine, chlorine, and bromine atoms and aliphatic groups containing 1 to 
4 carbon atoms, in particular, alkyl groups such as methyl, ethyl, propyl 
and butyl groups, and n represents an integer of 1 to 6. W is a linking 
group selected from the group consisting of 
##STR7## 
or a bonding group formed by combination of these linking groups, wherein 
b.sub.1 to b.sub.4 represent, same or different, hydrogen atom, halo9en 
atoms such as fluorine, chlorine and bromine atoms, hydrocarbon groups 
containing 1 to 7 carbon atoms such as methyl, ethyl, propyl, butyl, 
2-chloroethyl, 2-methoxyethyl, 2-methoxycarbonylethyl, benzyl, 
methoxybenzyl, phenyl, methoxyphenyl, methoxycarbonylphenyl groups and the 
like and --(W--Y) groups in the general formula (11), and b.sub.5 to 
b.sub.7 have the same meaning as Z.sub.1 and Z.sub.2 described above. Y is 
the foregoing hydrophilic group, i.e., --OH, SH, --CHO, --CN, --COOH, 
--SO.sub.2 H, --PO.sub.3 H.sub.2, --SO.sub.2 R.sub.1, 
##STR8## 
4- to 6-membered heterocyclic rings optionally containing at least one 
nitrogen atom or organosilane group, wherein R.sub.1 to R.sub.7 have the 
same meaning as the foregoing R.sub.1 to R.sub.7. 
In the general formula (II), Y can directly be bonded to the polymer main 
chain or when X is --O--, 
##STR9## 
Y can directly be bonded to X. 
In the general formula (II), a.sub.1 and a.sub.2 represent, same or 
different, hydrogen atom, halogen atoms such as fluorine, chlorine and 
bromine atoms, --COOH, --COOR.sub.5 and --CH.sub.2 COOR.sub.5 wherein 
R.sub.5 represents a hydrocarbon group containing 1 to 7 carbon atoms, in 
particular, the same hydrocarbon groups as in Z.sub.1 and Z.sub.2, and 
alkyl groups containing 1 to 4 carbon atoms, such as methyl, ethyl, propyl 
and butyl groups. 
Examples of the above described hydrophilic group-containing polymeric 
component are given below without limiting the scope of the present 
invention: 
##STR10## 
As other polymeric components which can be copolymerized with the above 
described hydrophilic group-containing polymeric components, for example, 
there can be used those represented by the following general formula 
(III), individually or in combination: 
##STR11## 
wherein d.sub.1 and d.sub.2 have the same meaning as a.sub.1 and a.sub.2 
in the general formula (II), P has the same meaning as X in the general 
formula (II) and Q is an alkyl group containing 1 to 18 carbon atoms, 
which can be substituted, such as methyl, ethyl, propyl, butyl, octyl, 
decyl, dodecyl, tridecyl, hexadecyl, octadecyl, 2-chloroethyl, 
3-bromopropyl, 2-methoxycarbonylethyl, 4-methoxycarbonylbutyl, 
4-methoxybutyl, 3-chloro-2-methoxypropyl, 3-chloro-2-ethoxycarbonylpropyl, 
2-glycidylpropyl, 3-bromo-2-acetyloxypropyl groups and the like; an 
alicyclic group containing 4 to 12 carbon atoms, which can be substituted, 
such as cyclopentyl, cyclohexyl, cyclooctyl, chlorocyclohexyl, 
bromocyclohexyl, 2-cyclohexylethyl, cyclohexylmethyl groups and the like; 
an alkenyl group containing 2 to 20 carbon atoms, which can be 
substituted, such as vinyl, allyl groups and the like; an aralkyl group 
containing 7 to 2 carbon atoms, which can be substituted, such as benzyl, 
phenethyl, 3-phenylpropyl, ethyl-2-phenylethyl, naphthylmethyl, 
2-naphthylethyl, chlorobenzyl, dichlorobenzyl, bromobenzyl, methylbenzyl, 
dimethylbenzyl, trimethylbenzyl, methoxybenzyl, dimethoxybenzyl, 
trimethoxybenzyl, methoxycarbonylbenzyl, acetamidebenzyl groups and the 
like; an aryl group containing 6 to 12 carbon atoms, which can be 
substituted, such as phenyl tolyl, xylyl mesitylene, naphthyl, 
chlorophenyl, dichlorophenyl trichlorophenyl, bromophenyl, chlorophenyl, 
methoxyphenyl, chloro-methyl-phenyl, methyl-methoxyphenyl, nitrophenyl, 
methoxycarbonylphenyl, acetamidephenyl, ethoxyphenyl, chloronaphthyl, 
ethoxycarbonylnaphthyl, propylphenyl, butylphenyl, chloromethylphenyl, 
methoxymethylphenyl and N-methylaminosulfonylphenyl groups; 4- to 
7-membered heterocyclic rings, i.e., any heterocyclic rings except that 
foregoing nitrogen atom-containing heterocyclic rings having hydrophilic 
property, which can be substituted, such as thiophene ring, furan ring, 
pyrane ring, benzopyrane ring, pyrrole ring, indole ring, quinoline ring, 
thiazole ring, oxazole ring and benzothiazole ring, the substituent 
corresponding to alkyl, alkenyl, alicyclic, aralkyl and aryl groups 
exemplified by the above described Q. 
Examples of the natural hydrophilic resin are described in detail in Kaimen 
Kagaku Kenkyukai "New Processing and Modifying Technique and Development 
of Uses of Water-Soluble Polymers and Aqueous Dispersion Type Resins", 
Keiei Kaihatsu Center Shuppan-bu (1981); Matao Nakamura "Water-Soluble 
Polymers (Suiyosei Kobunshi)" Kagaku Kogyo-sha (1973); R. L. Davidson 
"Handbook of Water-Soluble Gums and Resins" McGraw-Hill Book Company 
(1980); and "Encyclopedia of Polymer Science and Engineering" Vol. 3, pp. 
69-270, John Wiley and Sons (1985). 
Such natural hydrophilic resins include lignin, glucose starch, pullulan, 
cellulose, alginic acid, dextran, dextrin, gum guar, gum arabic, glycogen, 
lamiran, lichenin, nigeran and derivatives thereof. As these derivatives, 
there can be used preferably sulfonated, carboxylated, phosphated, 
sulfoalkylated, carboxyalkylated, alkylphosphated ones and salts thereof. 
Two or more natural hydrophilic resins can be used. 
In a preferred embodiment of the present invention, the resin grains 
consist of hydrophilic polymeric components as described above, in which 
polymer molecule chains are crosslinked to form higher order network 
structures. Thus, the hydrophilic resin grains are made hardly soluble or 
insoluble in water, so that the solubility of the resin in water is at 
most 80% by weight, preferably 50% by weight. 
The crosslinking according to the present invention can be carried out by 
known methods, that is, (1) method comprising crosslinking a polymer 
containing the hydrophilic component with various crosslinking agents or 
hardening agents, (2) method comprising polymerizing a monomer 
corresponding to the hydrophilic polymeric component in the presence of a 
multifunctional monomer or multifunctional oligomer containing two or more 
polymerizable functional groups to form a network structure among the 
molecules and (3) method comprising subjecting polymers containing the 
hydrophilic polymeric components and reactive groups to polymerization 
reaction or high molecular reaction and thereby effecting crosslinking. 
As the crosslinking agent in the above described method (1), 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). 
Examples of the crosslinking agent are organosilane compounds such as 
vinyltrimethoxysilane, vinyltributoxysilane, 
.gamma.-glycidoxypropyltrimethoxysilane, 
.gamma.-mercaptopropyltriethoxysilane, .gamma.-aminopropyltriethoxysilane 
and other silane coupling agents; polyisocyanate compounds such as 
tolylene diisocyanate, o-tolylene diisocyanate, diphenylmethane 
diisocyanate, triphenylmethane diisocyanate, polymethylenepolyphenyl 
isocyanate, hexamethylene diisocyanate, isophorone diisocyanate, high 
molecular polyisocyanate; polyol compounds such as 1,4-butanediol, 
polyoxypropylene glycol, polyoxyalkylene glycol, 1,1,1-trimethylolpropane 
and the like; polyamine compounds such as ethylenediamine, 
-hydroxypropylated ethylenediamine, phenylenediamine, 
hexamethylenediamine, N-aminoethylpiperazine, modified aliphatic 
polyamines and the like; polyepoxy group-containing compounds and epoxy 
resins, for example, as described in Kakiuchi Hiroshi "New Epoxy Resins 
(Shin Epoxy Jushi)" published by Shokodo (1985), and Kuniyuki Hashimoto 
"Epoxy Resins (Epoxy Jushi)" published by Nikkan Kogyo Shinbunsha (1969); 
melamine resins such as described in Ichiro Miwa and Hideo Matsunaga "Urea 
and Melamine Resins (Urea-Melamine Jushi)" published by Nikkan Kogyo 
Shinbunsha (1969); and poly(meth)acrylate compounds as described in Shin 
Ogawara, Takeo Saegusa and Toshirobu Higashimura "Oligomers" published by 
Kodansha (1976) and Eizo Omori "Functional Acrylic Resins" published by 
Technosystem (1985), for example, polyethylene glycol diacrylate, 
neopentyl glycol diacrylate, 1,6-hexanediol diacrylate, trimethylolpropane 
triacrylate, pentaerythritol polyacrylate, bisphenol A-diglycidyl ether 
diacrylate, oligoester acrylate and methacrylates thereof and the like. 
Of the hardening agents used in the above described method (1), natural 
hydrophilic resins such as gelatin, as the hardening agent, include those 
described in U.S. Pat. Nos. 3,057,723; 3,671,256; 3,396,029; 4,161,407 and 
4,207,109; British Patent No. 1,322,971; Japanese Patent Publication No. 
17112/1967; Japanese Patent Laid-Open Publication Nos. 94817/1976, 
66841/1981, 207243/1982 and 12132/1984; "The Theory of the Photographic 
Process" 4th Edition (T. H. James et al.) page 94 and "Polymeric Amines 
and Ammonium Salts" (E. J. Gehtals et al.) page 21. 
Examples of the polymerizable function group of the multifunctional monomer 
or multifunctional oligomer containing at least two polymerizable 
functional groups, used in the above described method (2), are: 
##STR12## 
Any of monomers or oligomers containing two or more same or different ones 
of these polymerizable functional groups can be used in the present 
invention. 
Of these monomers or oligomers, as the monomer or oligomer having two or 
more same polymerizable functional groups, there can be used styrene 
derivatives such as divinyl benzene and trivinyl benzene; esters of 
polyhydric alcohols such as ethylene glycol, diethylene glycol, 
triethylene glycol, polyethylene glycols Nos. 200, 400 and 600, 
1,3-butylene glycol, neopentyl glycol, dipropylene glyclol, polypropylene 
glycol, trimethylolpropane, trimethylolethane, pentaerythritol and the 
like or polyhydroxyphenols such as hydroquinone, resorcinol, catechol and 
derivatives thereof with methacrylic acid, acrylic acid or crotonic acid, 
vinyl ethers and allyl ethers; vinyl esters of dibasic acids such as 
malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, 
maleic acid, phthalic acid, itaconic acid and the like, allyl esters, 
vinylamides and allylamides; and condensates of polyamines such as 
ethylenediamine, 1,3-propylenediamine, 1,4-butylenediamine and the like 
with carboxylic acids containing vinyl groups such as methacrylic acid, 
acrylic acid, crotonic acid, allylacetic acid and the like. 
As the monomer or oligomer having two or more different polymerizable 
functional groups, there can be used, for example, ester derivatives or 
amide derivatives containing vinyl groups of carboxylic acids containing 
vinyl group, such as methacrylic acid, acrylic acid, methacryloylacetic 
acid, acryloylacetic acid, methacryloylpropionic acid, acryloylpropionic 
acid, itaconyloylacetic acid and itaconyloylpropionic acid, reaction 
products of carboxylic anhydrides with alcohols or amines such as 
allyloxycarbonylpropionic acid, allyloxycarbonylacetic acid, 
2-allyloxycarbonylbenzoic acid, allylaminocarbonylpropionic acid and the 
like, for example, vinyl methacrylate, vinyl acrylate, vinyl itaconate, 
allyl methacrylate, allyl acrylate, allyl itaconate, vinyl 
methacryloylacetate, vinyl methacryloylpropionate, allyl 
methacryloylpropionate, vinyloxycarbonylmethyl methacrylate, 
2-(vinyloxycarbonyl)ethyl ester of acrylic acid, N-allylacrylamide, 
N-allylmethacrylamide, n-allylitaconamide, methcaryloylpropionic acid 
allylamide and the like; and condensates of amino alcohols such as 
aminoethnaol, 1-aminopropanol, 1-aminobutanol, 1-aminohexanol, 
2-aminobutanol and the like with carboxylic acids containing vinyl groups. 
The monomer or oligomer containing two or more polymerizable functional 
groups of the present invention is generally used in a proportion of at 
most 10 mole %, preferably at most 5 mole % to all monomers, which is 
polymerized to form a resin. 
In the present invention, there can be used a polymer containing 
polymerizable double bond groups illustrative of which are the above 
described similar groups. The polymerization reaction among the polymers 
can be carried out jointly using the above described polymerizable 
multifunctional monomer, as well known in the art. 
The crosslinking of polymers by reacting reactive groups among the polymers 
and forming chemical bonds according to the foregoing method (3) can be 
carried out in the similar manner to the ordinary reactions of organic low 
molecular compounds, for example, as disclosed in Yoshio Iwakura and 
Keisuke Kurita "Reactive Polymers (Hannosei Kobunshi)" published by 
Kohdansha (1977) and Ryohei Oda "High Molecular Fine Chemical (Kobunshi 
Fine Chemical)" published by Kohdansha (1976). Combination of functional 
groups classified as Group A (hydrophilic polymeric component) and 
functional groups classified as Group B (polymers comprising components 
containing reactive groups) in the following Table 1 has well been known 
for effectively accomplishing the polymer reactions. 
TABLE 1 
______________________________________ 
Group A Group B 
______________________________________ 
COOH, PO.sub.3 H.sub.2 
##STR13## 
OH, SH 
NH.sub.2 COCl, SO.sub.2 Cl, 
cyclic acid anhydride 
SO.sub.2 H 
NCO, NCS, 
##STR14## 
______________________________________ 
As illustrated above, the resin grains of the present invention are polymer 
grains comprising hydrophilic group-containing polymeric components and 
having high order crosslinking structures among molecular chains, and for 
example, hydrogels or highly hygroscopic resins can be used therefor, as 
described in L. H. Sperling "Interpenetrating Polymer Networks and Related 
materials" Plenum Press (1981), "Encyclopedia of Polymer Science and 
Engineering" Vol. 8, pp. 279-340 (1985), J. D. Anclrade "Hydrogels for 
Medical and Related Application", ACS Symposium Series No. 31, American 
Chemical Society, Washington D.C. (1976), Eizo Omori "Development Tendency 
and Use Development of Highly Hygroscopic Resins (Kokyusuisei Jushi no 
Kaihatsu Doko to sono Yoto Tenkai)" Technoforum Shuppanbu KK (1987), 
Masahiro Irie "Production and Application of Functional High Molecular 
Gels (Kinosei Kobunshi Gel no Seizo to Oyo)" published by C. M. C KK 
(1987), Kenji Tanaka "Petrotech." 10, 25 (1987), "Nikkei New Materials" 
June 1, 1987, page 57, Jun Taguchi and Kunio Ishii "science and Industry 
(Kagaku to Kogyo)" 59, 188 (1985), Fusayoshi Masuda "Functioral Materials 
(Kino Zairyo)" No. 4, p. 36 (1982) and Yoshinori Monma "Chemical Industry 
(Kagaku Kogyo)" 38, 602 (1987). 
Examples of commercially available highly hygroscopic resins are Arasoap 
(-commercial name-, made by Arakawa Kagaku Kogyo KK), Wondergel 
(-commercial name-, made by Kao KK), KI Gel (-commercial name-, made by 
Kurare Isoprene KK), Sanwet (-commercial name-, made by Sanyo Kasei Kogyo 
KK), Sumika Gel (-commercial name, Sumitomo Kagaku Kogyo KK), Aquakeep 
(-commercial name-, made by Seitetsu Kagaku Kogyo KK), Lanseal 
(-commercial name-, made by Nippon Exslan Kogyo KK), Lion Polymer 
(-commercial name-, made by Lion KK), GP (-commercial name, made by Nippon 
Gosei Kagaku Kogyo KK), Aqualic (-commercial name-, made by Nippon 
Shokubai Kagaku Kogyo KK), Aquaprene (-commercial name-, made by Meisei 
Kagaku Kogyo KK), CLD (-commercial name-, made by Buckeye Cellulose Co.), 
D. W. A. L. (-commercial name-, Dow Chemical Co.), G. P. C. (-commercial 
name-, made by Grain Processing Co.), Aqualon (-commercial name-, made by 
Hercules Co.), Magic Water Gel (-commercial name-, made by Super Adsorbent 
Co.), Cecagum (-commercial name-, made by CEC Co.), Spon Signus 
(-commercial name-, made by Kanegafuchi Gosei Kagaku KK), super Rub 
(-commercial name-, made by Asahi Kasei Kogyo KK), etc. 
Production of fine grains or particles of the above described synthetic of 
natural hydrophilic resin having a specified grain diameter can be carried 
out by employing a dry or wet method well known in the art, for example, 
(a) a method comprising directly pulverizing the hydrophilic resin powder 
by a pulverizing mill of the prior art, such as ball mill, paint shaker, 
jet mill, etc. and thus obtaining fine grains and (b) a method of 
obtaining high molecular latex grains. The latter method of obtaining high 
molecular latex grains can be carried out according to the prior art 
method for producing latex grains of paints or liquid developers for 
electrophotography. That is, this method comprises dispersing the 
hydrophilic resin by the joint use of a dispersing polymer, more 
specifically previously mixing the hydrophilic resin and dispersion aid 
polymer or coating polymer, followed by pulverizing, and then dispersing 
the pulverized mixture in the presence of the dispersing polymer. 
For example, these methods are described in "Flowing and Pigment Dispersion 
of Paints" translated by Kenji Ueki and published by Kyoritsu Shuppan 
(1971), Solomon "Chemistry of Paints", "Paint and Surface Coating Theory 
and Practice", Yuji Harasaki "Coating Engineering (Coating Kogaku)" 
published by Asakura Shoten (1971), Yuji Harasaki "Fundamental Science of 
Coating (Kiso Kagaku of Coating)" by Maki Shoten (1977) and Japanese 
Patent Laid-Open Publication Nos. 96954/1987, 115171/1987 and 75651/1987. 
Furthermore, the prior art method of obtaining readily latex grains or 
particles by suspension polymerization or dispersion polymerization can 
also be used in the present invention, for example, as described in Soichi 
Muroi "Chemistry of High Molecular Latex (Kobunshi Latex no Kagaku)" 
published by Kobunshi Kankokai (1970), Taira Okuda and Hiroshi Inagaki 
"Synthetic Resin Emulsions (Gosei Jushi Emulsion)" published by Kobunshi 
Kankokai (1978), Soichi Muroi "Introduction to High Molecular Latexes 
(Kobunshi Latex Nyumon)" published by Kobunsha (1983). 
In the present invention, it is preferable to use a method of obtaining 
high molecular latex grains, whereby resin grains with an average grain 
diameter of at most 1.0 .mu.m can readily be obtained. 
In the electrophotographic lithographic printing plate precursor of the 
present invention, formation of a photoconductive layer can be carried out 
by any of methods of dispersing photoconductive zinc oxide in an aqueous 
system, for example, described in Japanese Patent Publication Nos. 
450/1976, 18599/1972 and 41350/1971 and methods of dispersing in a 
non-aqueous solvent system, for example, described in Japanese Patent 
Publication No. 31011/1975 and Japanese Patent Laid-Open Publication Nos. 
54027/1978, 20735/1979, 202544/1982 and 68046/1983. If water remains in 
the photoconductive layer, however, the electrophotographic property is 
deteriorated, and accordingly, the latter methods using a non-aqueous 
solvent system is preferable. Therefore, in order to adequately disperse 
the hydrophilic resin latex grains of the present invention in the 
photoconductive layer dispersed in a non-aqueous system, the latex grains 
are preferably non-aqueous system latex grains. 
When a high molecular latex is synthesized by the dispersion polymerization 
method in a non-aqueous solvent system, the average grain diameter of the 
latex grains can readily be adjusted to at most 1 .mu.m while 
simultaneously obtaining grains of monodisperse system with a very narrow 
distribution of grain diameters. Such a method is described in, for 
example, K. E. J. Barrett "Dispersion Polymerization in Organic Media" 
John Wiley & Sons (1975), Koichiro Murata "Polymer Processings (Kobunshi 
Kako)" 23, 20 (1974), Tsunetaka Matsumoto and Toyokichi Tange "Journal of 
Japan Adhesive Association (Nippon Setchaku Kyokaishi)" 9, 183 (1973), 
Toyokichi Tange "Journal of Japan Adhesive Association" 23, 26 (1987), D. 
J. Walbridge "NATO. Adv. Study Inst. Ser. E." No. 67, 40 (1983), British 
Patent Nos. 893,429 and 934,038 and U.S. Pat. Nos. 1,122,397, 3,900,412 
and 4,606,989, and Japanese Patent Laid-Open Publication Nos. 179751/1985 
and 185963/1985. 
As the binder resin of the present invention, there can be used all of 
known resins, typical of which are vinyl chloride-vinyl acetate 
copolymers, styrenebutadiene copolymers, styrene-methacrylate copolymers, 
methacrylate copolymers, acrylate copolymers, vinyl acetate copolymers, 
polyvinyl butyral, alkyd resins, silicone resins, epoxy resins, epoxyester 
resins, polyester resins and the like, as described in Takaharu Kurita and 
Jiro Ishiwataru "High Molecular Materials (Kobunshi)" 17, 278 (1968), 
Harumi Miyamoto and Hidehiko Takei "Imaging" No. 8, page 9 (1973), Koichi 
Nakamura "Practical Technique of Binders for Recording Materials (Kiroku 
Zairyoyo Binder no Jissai Gijutsu)" Section 10, published by C. M. C. 
Shuppan (1985), D. D. Tatt, S. C. Heidecker "Tappi" 49, No. 10, 439 
(1966), E. S. Baltazzi, R. G. Blanckette et al. "Photo Sci. Eng." 16, No. 
5, 354 (1972), Nguyen Chank Khe, Isamu Shimizu and Eiichi Inoue "Journal 
of Electrophotographic Association (Denshi Shashin Gakkaishi)" 18, No. 2, 
28 (1980), Japanese Patent Publication No. 31011/1975, Japanese Patent 
Laid-Open Publication Nos. 54027/1978, 20735/1979, 202544/1982 and 
68046/1983. 
As the non-aqueous solvent for the non-aqueous system latex, there can be 
used any of organic solvents having a boiling point of at most 200.degree. 
C., individually or in combination. Useful examples of the organic solvent 
are alcohols such as methanol, ethanol, propanol, butanol, fluorinated 
alcohols and benzyl alcohol, ketones such as acetone, methyl ethyl ketone, 
cyclohexanone and diethyl ketone, ethers such as diethyl ether, 
tetrahydrofuran and dioxane, carboxylic acid esters such as methyl 
acetate, ethyl acetate, butyl acetate and methyl propionate, aliphatic 
hydrocarbons containing 6 to 14 carbon atoms such as hexane, octane, 
decane, dodecane, tridecane, cyclohexane and cyclooctane, aromatic 
hydrocarbons such as benzene, toluene, xylene and chlorobenzene and 
halogenated hydrocarbons such as methylene chloride, dichloroethane, 
tetrachloroethane, chloroform, methylchloroform, dichloropropane and 
trichloroethane. 
More specifically, there are given (meth)acrylic copolymers containing at 
least 30% by weight, based on the total amount of the copolymer, of a 
monomer represented by the following general formula (IV) as a copolymeric 
component and homopolymers of the monomer represented by the general 
formula (IV): 
##STR15## 
wherein X is hydrogen atom, a halogen atom such as chlorine or bromine 
atom, cyano group, an alkyl group containing 1 to 4 carbon atoms, or 
--CH2COOR" wherein R" is an alkyl group containing 1 to 6 carbon atoms, 
which can be substituted, such as methyl, ethyl, propyl, butyl, heptyl, 
hexyl, 2-methoxyethyl or 2-chloroethyl group, an aralkyl group containing 
7 to 12 carbon atoms, which can be substituted, such as benzyl phenethyl, 
3-phenylpropyl, 2-phenylpropyl, chlorobenzyl, bromobenzyl, methoxybenzyl 
or methylbenzyl group, or an aryl group containing 6 to 12 carbon atoms, 
which can be substituted, such as phenyl, tolyl, xylyl, chlorophenyl 
dichlorophenyl, methoxyphenyl, bromophenyl or naphthyl group, and R' 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, methoxybenzyl, ethoxybenzyl or 
methylbenzyl group, a cycloalkyl group containing 5 to 8 carbon atoms, 
which can be substituted, such as cyclopentyl, cyclohexyl or cycloheptyl 
group, or an aryl group such as phenyl, tolyl, xylyl, mesityl, naphthyl, 
methoxyphenyl, ethoxyphenyl, chlorophenyl or dichlorophenyl group. 
Examples of other monomers to be copolymerized with the monomer represented 
by the general formula (IV) are vinyl or allyl esters of aliphatic 
carboxylic acids, such as vinyl acetate, vinyl propionate, vinyl butyrate, 
allyl acetate, allyl propionate and the like; unsaturated carboxylic acids 
such as crotonic acid, itaconic acid, maleic acid and fumaric acid, or 
esters or amides of these unsaturated carboxylic acids; styrene or styrene 
derivatives such as vinyltoluene and .alpha.-methylstyrene; 
.alpha.-olefins and vinyl group-substituted heterocyclic compounds such as 
N-vinylpyrrolidone, acrylonitrile and methacrylonitrile. 
The binder resin used in the present invention has preferably a molecular 
weight of 10.sup.3 to 10.sup.6, more preferably 5.times.10.sup.3 to 
5.times.10.sup.5 and a glass transition point of -10.degree. C. to 
120.degree. C., more preferably 0.degree. C. to 85.degree. C. 
The above described binder resin serves to not only fix photoconductive 
zinc oxide and the foregoing hydrophilic resin grains in a photoconductive 
layer, but also combine closely the photoconductive layer with a support. 
If the quantity of the binder resin is too small, therefore, the fixing 
and bonding strength is lowered, so that the printing durability as a 
printing plate is reduced and repeated use of the printing plate is 
impossible, while if too large, the printing durability and repeated use 
can be improved, but the electrophotographic property is deteriorated as 
described above. 
In the present invention, therefore, 10 to 60% by weight, preferably 15 to 
40% by weight of the above described binder resin is used to 100 parts by 
weight of photoconductive zinc oxide. 
In the present invention, if necessary, various coloring matters or dyes 
can be used as a spectro sensitizer, illustrative of which are carbonium 
dyes, diphenylmethane dyes, triphenylmethane dyes, xanthene dyes, 
phthalein dyes, polymethine dyes such as oxonol dyes, merocyanine dyes, 
cyanine dyes, rhodacyanine dyes, styryl dyes etc. and phthalocyanine dyes 
which can contain metals, as described in Harumi Miyamoto and Hidehiko 
Takei "Imaging" No. 8, page 12 (1973), C. Y. Young et al. "RCA Review" 15, 
469 (1954), Kohei Kiyota et al. "Denki Tsushin Gakkai Ronbunshi" J63-C 
(No. 2), 97 (1980), Yuji Harasaki et al. "Kogyo Kagaku Zasshi" 66, 78 and 
188 (1963) and Tadaaki Tani "Nippon Shashin Gakkaishi" 35, 208 (1972). 
For example, those using carbonium dyes, triphenylmetahe dyes, xanthene 
dyes or phthalein dyes are described in Japanese Patent Publication No. 
452/1976, Japanese Patent Laid-Open Publication Nos. 90334/1975, 
114227/1975, 39130/1978, 82353/1978 and 16456/1982 and U.S. Pat. Nos. 
3,052,540 and 4,054,450. 
As the polymethine dyes such as oxonol dyes, merocyanine dyes, cyanine dyes 
and rhodacyanine dyes, there can be used dyes described in F. M. Harmmer 
"The Cyanine Dyes and Related Compounds" and specifically dyes described 
in U.S. Pat. Nos. 3,047,384, 3,110,591, 3,121,008, 3,125,447, 3,128,179, 
3,132,942 and 3,622,317; British Patent Nos. 1,226,892, 1,309,274 and 
1,405,898; and Japanese Patent Publication Nos. 7814/1973 and 18892/1980. 
The 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. Pat. Nos. 3,619,154 and 4,175,956; and "Research 
Disclosure" 216, pages 117-118 (1982). 
The photoreceptor of the present invention is excellent in that its 
performance is hardly fluctuated even if it is used jointly with various 
sensitizing dyes. Furthermore, various additives for electrophotographic 
light-sensitive layers, such as chemical sensitizers, well known in the 
art can jointly be used as occasion demands, for example, electron 
accepting compounds such as benzoquinone, chloranil, acid anhydrides, 
organic carboxylic acids and the like, described in the foregoing 
"Imaging" No. 8, page 12 (1973) and polyarylalkane compounds hindered 
phenol compounds, p-phenylenediamine compounds and the like, described in 
Hiroshi Komon et al. "Latest Development and Practical Use of 
Photoconductive Materials and Light-Sensitive Materials (Saikin no 
Kododenzairyo to Kankotai no Kaihatsu to Jitsuyoka)" Sections 4 to 6, 
published by Nippon Kagaku Joho Shuppanbu (1986). 
The amounts of these additives re not particularly limited, but are 
generally 0.0001 to 2.0% by weight based on 100 parts by weight of the 
photoconductive zinc oxide. 
The thickness of the photoconductive layer is generally 1 to 100 .mu.m, 
preferably 10 to 50 .mu.m. 
When in a photoreceptor of laminate type consisting of a charge generating 
layer and charge transporting layer, a photoconductive layer is used as 
the charge producing layer, the thickness of the charge producing layer is 
generally 0.01 to 1 .mu.m, preferably 0.05 to 0.5 .mu.m. 
The photoconductive layer of the present invention can be provided on a 
support as well known in the art. Generally, a support for an 
electrophotographic light-sensitive layer is preferably electroconductive 
and as the electroconductive support, there can be used, as known in the 
art, metals or substrates such as papers, plastic sheets, etc. which are 
made electroconductive by impregnating low resistance materials therein, 
substrates whose back surface, opposite to the surface to be provided with 
a light-sensitive layer, is made electroconductive, which is further 
coated with at least one layer for the purpose of preventing it from 
curling; the above described support provided with, on the surface 
thereof, a water proof adhesive layer; the above described support 
optionally provided with, on the surface layer, one or more pre-coat 
layer; and papers laminated with plastics which are made 
electroconductive, for example, by vapor deposition of Al or the like 
thereon. Examples of the substrates or materials which are 
electroconductive or made electroconductive are described in Yukio 
Sakamoto "Electrophotography (Denshi Shashin)" 14 (No. 1), pages 2 to 11 
(1975), Hiroyuki Moriga "Introduction to Chemistry of Special Papers 
(Nyumon Tokushushi no Kagaku)" Kobunshi Kankokai (1975}, M. F. Hoover "J. 
Macromol. Sci. Chem." A 4 (6), pp. 1327-1417 (1970), 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. That is, the electrophotographic lithographic 
printing plate precursor is electrostatically charged substantially 
uniformly in a dark place and imagewise exposed to form an electrostatic 
latent image by an exposing method, for example, by scanning exposure 
using a semiconductor laser, He-Ne laser, etc., by reflection imagewise 
exposure using a xenon lamp, tungsten lamp, fluorescent lamp, etc. as a 
light source or by contact exposure through a transparent positive film. 
The resulting electrostatic latent image is developed with a toner by any 
of various known development methods, for example, cascade development, 
magnetic brush development, powder cloud development, liquid development, 
etc. Above all, the liquid development method capable of forming a fine 
image is particularly suitable for making a printing plate. The thus 
formed toner image can be fixed by a known fixing method, for example, 
heating fixation, pressure fixation, solvent fixation, etc. 
The printing plate having the toner image, formed in this way, is then 
subjected to a processing for rendering hydrophilic the non image area in 
conventional manner using the so-called oil-desensitizing solution. The 
oil-desensitizing solution of this kind include processing solutions 
containing, as a predominant component, cyanide compounds such as 
ferrocyanides or ferricyanides, cyanide-free processing solutions 
containing, as a predominant component, amine cobalt complexes, phytic 
acid or its derivatives or guanidine derivatives, processing solutions 
containing, as a predominant component, organic acids or inorganic acids 
capable of forming chelates with zinc ion, and processing solutions 
containing water-soluble polymers. 
For example, the cyanide compound-containing processing solutions are 
described in Japanese Patent Publication Nos. 9045/1969 and 39403/1971 and 
Japanese Patent Laid-Open Publication Nos. 76101/1977, 107889/ and 
117201/1979. The phytic acid or its derivatives-containing processing 
solutions are described in Japanese Patent Laid-Open Publication Nos. 
83807/1978, 83805/1978, 102102/1978, 109701/1978, 127003/1978, 2803/1979 
and 44901/1979. The metal complex-containing processing solutions are 
described in Japanese Patent Laid-Open Publication Nos. 104301/1978, 
14013/1978 and 18304/1979 and Japanese Patent Publication No. 28404/1968. 
The inorganic acid- or organic acid-containing processing solutions are 
described in Japanese Patent Publication Nos. 13702/1964, 10308/1965, 
28408/1968 and 26124/1965 and Japanese Patent Laid-Open Publication No. 
118501/1976. The guanidine compound-containing processing solutions are 
described in Japanese Patent Laid-Open Publication No. 111695/1981. The 
water-soluble polymer-containing processing solutions are described in 
Japanese Patent Laid-Open Publication Nos. 36402/1974, 126302/1977, 
134501/1977, 49506/1978, 59502/1978 and 104302/1978 and Japanese Patent 
Publication Nos. 9665/1963, 22263/1964, 763/1965 and 2202/1965. 
The oil-desensitizing treatment can generally be carried out at a 
temperature of about 10.degree. C. to about 50.degree. C., preferably from 
20.degree. C. to 35.degree. C., for a period of not longer than about 5 
minutes. 
In any of the above described oil-desensitizing solutions, the zinc oxide 
in the surface layer as the photoconductive is ionized to be zinc ion 
which causes a chelation reaction with a compound capable of forming a 
chelate in the oil-desensitizing solution to form a zinc chelate compound. 
This is precipitated in the surface layer to render the non-image area 
hydrophilic. 
Thus, the printing plate precursor of the present invention can be 
converted into a printing plate by the oil-desensitizing processing with 
an oil-desensitizing solution. 
The present invention will now be illustrated in greater detail by way of 
examples, but it should be understood that the present invention is not 
limited thereto. 
EXAMPLES 
Preparation Example 1 of Resin Grains 
A mixed solution of 95 g of dodecyl methacrylate, 5 g of acrylic acid and 
200 g of toluene was heated to 70.degree. C. while stirring under a 
nitrogen stream, and 1.5 g of azobis(isobutyronitrile) (referred to as A. 
I.B.N.) was added thereto and reacted for 8 hours. To this reaction 
mixture were added 12 g of glycidyl methacrylate, 1 g of 
t-butylhydroquinone and 0.8 g of N,N-dimethyldodecylamine, followed by 
allowing the mixture to react at 100.degree. C. for 15 hours (Dispersed 
Resin (I). 
A mixture of 7.5 g (as solid content) of the above described Dispersed 
Resin I, 50 g of 2-hydroxyethyl methacrylate and 200 g of n-heptane was 
heated to 65.degree. C. while stirring under a nitrogen stream, and 0.7 g 
of 2,2-azobis(isovaleronitrile) (referred to as A. I. V. N.) was then 
added thereto and reacted for 6 hours. 
After passage of 20 minutes from the addition of the initiator (A. I. V. 
N.), the homogeneous solution became slightly opaque, the reaction 
temperature being raised to 90.degree. C. After cooling, the reaction 
product was passed through a nylon cloth of 200 mesh to obtain a white 
dispersion having an average grain diameter of 0.19 .mu.m as a white 
latex. 
Preparation Example 2 of Resin Grains 
A mixture of 50 g of acrylonitrile, 8 g of Dispersed Resin I (as solid 
content) and 200 g of n-hexane was heated to 55.degree. C. while stirring 
under a nitrogen stream, and 0.5 g of A. I. V. N. was added thereto and 
reacted for 4 hours, thus obtaining a white dispersion. After cooling, the 
reaction product was passed through a nylon cloth of 200 mesh. The 
resulting dispersion was a latex with an average grain diameter of 0.08 
.mu.m. 
Preparation Example 3 of Resin Grains 
Preparation Example 1 was repeated except using a mixture of 50 g of 
N-vinylpyrrolidone 10 g of Dispersed Resin (as solid content) and 200 g of 
toluene, thus obtaining a white latex with an average grain size of 0.30 
.mu.m. 
Preparation Example 4 of Resin Grains 
A mixture of 31.5 g of ethylene glycol, 51.8 g of phthalic anhydride, 6.0 g 
of methacrylic acid, 10 g of trichloroethylene and 0.7 g of 
p-toluenesulfonic acid was heated and reacted for 6 hours in such a manner 
that the reaction temperature was raised from 107.degree. C. to 
150.degree. C. in 6 hours, while removing water byproduced by the reaction 
by the Dean-Stark method. 
A mixture of 6 g of methacrylic acid, 76 g of chloroform, 11.6 g of ethanol 
and 5.8 g of Dispersed Resin II obtained by the above described reaction 
(as solid content) was then refluxed under a nitrogen stream. 0.8 g of A. 
I. B. N. was then added thereto and reacted for 3 hours to obtain a white 
dispersion, latex with an average grain diameter of 0.40 .mu.m. 
Preparation Example 5 of Resin Grains 
Preparation Example 1 was repeated except using a mixture of 50 g of 
N,N-dimethylaminoethyl methacrylate, 15 g of poly(dodecyl methacrylate) 
and 300 g of toluene, thus obtaining a white dispersion with an average 
grain diameter of 0.28 .mu.m. 
Preparation Example 6 of Resin Grains 
A mixture of 10 g of (2-hydroxyethyl acrylate/methyl methacrylate) 
copolymer (weight ratio 1/1) powder, 2 g of (dodecyl methacrylate/acrylic 
acid) copolymer (weight ratio 95/5) and 100 g of toluene was ball milled 
for 48 hours to obtain a dispersion, i.e. latex with an average grain 
diameter of 0.38 .mu.m. 
Preparation Example 7 of Resin Grains 
A mixture of 10 g of (vinyl alcohol/methacrylic acid) copolymer (weight 
ratio 7/3), 1.8 g of (decyl methacrylate/N,N-dimethylaminoethyl acrylate) 
copolymer weight ratio 95/5) and 100 g of toluene was ball milled for 56 
hours to obtain a dispersion, latex with an average grain diameter of 0.32 
.mu.m. 
Example 1 
A mixture of 200 g of photoconductive zinc oxide, 40 g of (ethyl 
methacrylate/acrylic acid) copolymer (weight component ratio 97/3, weight 
average molecular weight 63,000), 1.5 g [as solid content) of the resin 
grains obtained in Preparation Example 1, 0.06 g of Rose Bengal and 300 g 
of toluene was ball milled for 2 hours. The thus resulting light-sensitive 
layer forming dispersion was applied to a paper rendered electrically 
conductive to give an adhered quantity on dry basis of 25 g/m.sup.2 by a 
wire bar coater, followed by drying at 110.degree. C. for 30 seconds. The 
thus coated paper was allowed to stand in a dark place at a temperature of 
20.degree. C. and a relative humidity of 65% for 24 hours to prepare an 
electrophotographic light-sensitive material. Observation of the surface 
layer and sectional layer of the resulting light-sensitive material by an 
electron microscope taught that the zinc oxide had a maximum grain 
diameter of about 1 .mu.m and an average grain diameter of about 0.3 to 
0.5 .mu.m. 
Comparative Example 1 
The procedure of Example 1 was repeated except not using 1.5 g (as solid 
content) of the resin grains obtained in Preparation Example 1 to prepare 
an electrophotographic light-sensitive material. 
These light-sensitive materials were then subjected to evaluation of the 
electrostatic characteristics and reproduced image quality, in particular, 
under ambient conditions of 30.degree. C. and 80% RH. Furthermore, when 
using these light-sensitive materials as a master plate for offset 
printing, the oil-desensitivity of the photoconductive layer in terms of a 
contact angle of the photoconductive layer with water after 
oil-desensitization and the printing performance in terms of a stain 
resistance and printing durability. 
The image quality and printing performance were evaluated using a 
lithographic printing plate obtained by subjecting the light-sensitive 
material to exposure and development by means of an automatic plate making 
machine, ELP 404 V (-commercial name-, made by Fuji Photo Film Co., Ltd.) 
using a developing agent, ELP-T (-commercial name-, made by Fuji Photo 
Film Co., Ltd.) to form an image and etching by means of an etching 
processor using an oil-desensitizing solution, ELP-E (-commercial name-, 
made by Fuji Photo Film Co., Ltd.). As a printing machine, Hamada Star 800 
SX (-commercial name-, made by Hamada Star KK) was used. 
The results are shown in Table 2: 
TABLE 2 
______________________________________ 
Comparative 
Example 1 
Example 1 
______________________________________ 
Electrostatic 
Characteristics.sup.(1) 
Vo (-V) 580 555 
DRR (%) 85 88 
E.sub.1/10 (lux .multidot. sec) 
12.0 11.5 
Image Quality.sup.(2) 
I: (20.degree. C., 65%) 
good good 
II: (30.degree. C., 80%) 
good good 
Contact Angle with 
less than 10.degree. 
40-50.degree. 
Water.sup.(3) (degrees) large dispersion 
Background stain.sup.(4) 
I no yes 
II no marked 
Printing no stain even 
marked background 
Durability.sup.(5) 
after 10000 
stain from 
prints printing start 
______________________________________ 
The characteristic item described in Table 2 are evaluated as follows: 
1) Electrostatic Characteristics 
Each of the light-sensitive materials was negative charged to a surface 
potential Vo (-V: negatively charged) by corona discharge at a voltage of 
6 kV for 20 seconds in a dark room at a temperature of 20 .degree. C. and 
relative humidity of 65% using a paper analyzer (Paper Analyzer Sp-428 
-commercial name-manufacture by Kawaguchi Denki KK) and after allowed to 
stand for 10 seconds, the surface potential V.sub.10 was measured. Then, 
the sample was further allowed to stand in the dark room as it was for 60 
seconds to measure the surface potential V.sub.70, thus obtaining the 
retention of potential after the dark decay for 60 seconds, i.e., dark 
decay retention ratio (DRR (%)) represented by (V.sub.70 
/V.sub.10).times.100 (%). Moreover, the surface of the photoconductive 
layer was negatively charged to -400 V by corona discharge, then 
irradiated with visible ray at an illumination of 2.0 lux and the time 
required for dark decay of the surface potential (V.sub.10) to 1/10 was 
measured to evaluate an exposure quantity E.sub.1/10 (lux.sec). 
2) Image quality 
Each of the light-sensitive materials was allowed to stand for a whole day 
and night under the following ambient conditions and a reproduced image 
was formed thereon using an automatic printing plate making machine 
KLP-404 V (-commercial name-, made by Fuji Photo Film Co., Ltd., Ltd.) to 
visually evaluate the fog and image quality: (I) 20.degree. C., 65% RH and 
(II) 30.degree. C., 80% RH. 
3) Contact Angle with Water 
Each of the light-sensitive materials was passed once through an etching 
processor using an oil-desensitizing solution ELP-E (-commercial name-, 
made by Fuji Photo Film Co., Ltd.) 5 times diluted with distilled water to 
render the surface of the photoconductive layer oil-desensitized. On the 
thus oil-desensitized surface was placed a drop of 2 .mu.l of distilled 
water and the contact angle formed between the surface and water was 
measured by a goniometer. 
4) Background Stain of Print 
Each of the light-sensitive materials was processed by an automatic 
printing plate making machine ELP-404 to form a toner image and subjected 
to oil-desensitization under the same conditions as in the above described 
item (3). The resulting printing plate was mounted, as an offset master, 
on a printing machine, Hamada Star 800 SX (-commercial name- made by 
Hamada Star KK) and printing was carried out on fine papers to obtain 500 
prints. All the prints thus obtained were subjected to visual evaluation 
of the background stains, which was designated as Background Stain I of 
the print. 
Background Stain II of the print was defined in an analogous manner to 
Background Stain I as defined above except that the moistening water 
during printing was 2-fold diluted. Case II corresponds to a printing 
carried out under severe conditions than Case I. 
5) Printing Durability 
The printing durability was defined by the number of prints which could be 
obtained without forming background stains on the non-image areas of the 
print and meeting with any problem on the image quality of the image areas 
by printing under the evaluation conditions corresponding to Background 
Stain II of the above described item 4). The more the prints, the better 
the printing durability. 
As can be seen from Table 2, the light-sensitive material of the present 
invention exhibited excellent electrostatic characteristics of the 
photoconductive layer and gave a reproduced image free from background 
stains and excellent in image quality. This tells that the photoconductive 
material and binder resin are sufficiently combined and the added 
hydrophilic resin grains have no bad influences upon the electrostatic 
characteristics. 
When the light-sensitive material of the present invention is used as a 
master plate for offset printing, the oil-desensitizing processing can 
well be accomplished by one passage through a processor even with a 
diluted oil-desensitizing solution and consequently, a non-image area is 
so rendered hydrophilic that the contact angle of the non-image area with 
water be smaller than 10.degree. . Thus, it is found by observation of 
real prints that the printing plate precursor of the present invention can 
form a clear image and produce more than 10,000 clear prints without 
background stains. 
In Comparative Example 1, on the other hand, the electrophotographic 
properties (image quality) were good, but in the oil-desensitizing 
processing as a master plate for offset printing, a non-image area was not 
sufficiently rendered hydrophilic, so that in real printing, background 
stains markedly occurred from the beginning in the print. 
It will clearly be understood from these considerations that according to 
only the present invention, there can be obtained an electrophotographic 
photoreceptor capable of satisfying electrostatic properties as well as 
printing adaptability. 
Examples 2 to 5 
The procedure of Example 1 was repeated except using 1.5 g (as solid 
content) cf each of the resin grains shown in Table 3 instead of the resin 
grains obtained in Preparation Example 1, thus obtaining each of 
electrophotographic light-sensitive materials. 
These light-sensitive materials were subjected to the similar evaluations 
to Example 1 to obtain results as shown in Table 3: 
TABLE 3 
______________________________________ 
Contact Number of 
Hydrophilic 
Image Angle Printing 
Example 
Resin Grains 
Quality with Water 
Durability 
______________________________________ 
2 Preparation 
excellent in 
12.degree. 
more than 
Example 2 and II of 10,000 prints 
Table 2 free from 
stains 
3 Preparation 
excellent in 
8.degree. 
more than 
Example 3 and II of 10,000 prints 
Table 2 free from 
stains 
4 Preparation 
excellent in 
5.degree. or less 
more than 
Example 4 and II of 10,000 prints 
Table 2 free from 
stains 
5 Preparation 
excellent in 
5.degree. or less 
more than 
Example 5 and II of 10,000 prints 
Table 2 free from 
stains 
______________________________________ 
As can be seen from the results of Table 3, the electrophotographic 
photoreceptor of the present invention has excellent electrophotographic 
properties and is capable of giving a number of clear prints free from 
background stain. 
Examples 6 to 12 
The procedure of Example 1 was repeated except using 1.0 g (as solid 
content) of each of the resin grains shown in Table 4 instead of the resin 
grains obtained in Preparation Example 1, thus obtaining each of 
light-sensitive materials. 
These light-sensitive materials were subjected to measurement of the 
electrostatic characteristics and printing properties in an analogous 
manner to Example 1, thus obtaining good results. In real printing, more 
than 10,000 prints wee obtained without occurrence of any background 
stain. 
TABLE 4 
__________________________________________________________________________ 
Average 
Example 
Resin Grains Grain Diameter 
__________________________________________________________________________ 
##STR16## 0.28 .mu.m 
7 
##STR17## 0.30 .mu.m 
8 
##STR18## 0.25 .mu.m 
9 
##STR19## 0.45 .mu.m 
10 
##STR20## 0.17 .mu.m 
11 
##STR21## 0.25 .mu.m 
12 
##STR22## 0.30 .mu.m 
__________________________________________________________________________ 
EXAMPLE 13 
A mixed solution of 50 g of vinylbenzenecarboxylic acid and 200 g of methyl 
cellosolve was heated to 70.degree. C. under a nitrogen stream while 
stirring, and 1.0 g of A. I. B. N. was added thereto, followed by reacting 
for 8 hours. After cooling, the reaction mixture was subjected to a 
reprecipitation treatment in 1.0 l of water-methanol (volume ratio 1/1) to 
obtain a white powder, which was then dried. The yield was 42 g. 
A mixture of 1.8 g of this white powder (polyvinylbenzenecarboxylic acid), 
200 g of photoconductive zinc oxide, 40 g of (ethyl methacrylate/acrylic 
acid) copolymer (weight component ratio 97/3, weight average molecular 
weight 63,000), 0.3 g of Rose Bengal, 0.2 g of tetrabromophenol blue and 
300 g of toluene was dispersed in a ball mill for 2 hours to prepare a 
light-sensitive coating composition. 
The resulting light-sensitive composition was coated onto a sheet of paper 
having been rendered electrically conductive to give a dry coverage of 25 
g/m.sup.2 by a wire bar coater, followed by drying at 110.degree. C. for 
30 seconds. The thus coated paper was allowed to stand in a dark place at 
a temperature of 20.degree. C. and a relative humidity of 65% for 24 hours 
to prepare an electrophotographic light-sensitive material. 
Comparative Example 2 
A dispersion treatment was carried out for 2 hours in an analogous manner 
to Example 13 except not using 1.8 g of the resin powder 
(polyvinylbenzenecarboxylic acid). To the resulting dispersed product was 
added 1.8 g of the above described resin powder and the mixture was 
dispersed in a ball mill for 10 minutes to prepare a light-sensitive 
coating composition. Using the resulting light-sensitive composition, an 
electrophotographic light-sensitive material was prepared in an analogous 
manner to Example 13. 
These light-sensitive materials were then subjected to evaluation of the 
film property (surface smoothness) and as in Example 1, evaluation of the 
electrophotographic properties and printing properties. 
TABLE 5 
______________________________________ 
Comparative 
Example 13 
Example 2 
______________________________________ 
Smoothness of 105 45 
Photoconductive Layer* 
(sec/cc) 
Electrostatic 
Characteristics.sup.(1) 
Vo (-V) 540 480 
DRR (%) 86 75 
E.sub.1/10 (lux .multidot. sec) 
11.4 8.5 
Image Quality 
I: (20.degree. C., 65%) 
good disappearance 
of fine lines, 
letters; blur 
of solid areas 
II: (30.degree. C., 80%) 
good no image density 
Dmax 
Contact Angle with 
less than 10.degree. 
10-25.degree. 
Water (degrees) large dispersion 
Background stain 
I no yes 
II no marked 
Printing no stain even 
occurrence of 
Durability after 10000 disapearance 
prints of image areas 
and background 
stain 
______________________________________ 
Note: *Smoothness of Photoconductive Layer 
The smoothness (sec/cc) was measured by means of a Beck's smoothness 
tester (manufactured by Kumagaya Riko KK) under an air volume condition o 
1 cc. 
In Examples of the present invention and Comparative Example, the same 
resin powder was used but changing the time for dispersing it so that the 
grain size of the resin powder be different. This difference can be judged 
by measuring the smoothness of the photoconductive layer, since the 
presence of coarser or larger grains reduces the value of the smoothness, 
i.e., renders the surface rough. 
In Comparative Example 2, the dispersion time was shorter after the 
addition of the resin powder, resulting in a reduced smoothness of the 
photoconductive layer due to the effect of the resin powder added 
afterward. In the electrostatic characteristics, DRR was lowered and 
consequently, the apparent E.sub.1/10 also became smaller. 
In a reproduced image, there were a number of disappearances in image areas 
and blurs of solid areas and this phenomenon further became remarkable 
under ambient conditions of high temperature and high humidity, thus 
lowering Dmax, i.e., to less than 0.6. 
Evaluation of the printing property as a master plate for offset printing 
shoed areas free from background stain and areas dotted with marked 
background stains. 
It will clearly be understood from these results that only the 
light-sensitive material of the present invention, that is, the case where 
the coexistent resin grains are sufficiently small can give better 
effects. 
Preparation Example 8 of Resin Grains 
A mixed solution of 95 g of dodecyl methacrylate, 5 g of acrylic acid and 
200 g of toluene was heated to 70.degree. C. while stirring under a 
nitrogen stream, and 1.5 g of azobis(isobutyronitrile) (referred to as A. 
I.B.N.) was added thereto and reacted for 8 hours. To this reaction 
mixture were added 12 g of glycidyl methacrylate, 1 g of 
t-butylhydroquinone and 0.8 g of N,N-dimethyldodecylamine, followed by 
allowing the mixture to react at 100.degree. C. for 15 hours (Dispersed 
Resin I). 
A mixture of 7.5 g (as solid content) of the above described Dispersed 
Resin I, 50 g of 2-hydroxyethyl methacrylate, 1 g of divinyl adipate and 
200 g of n-heptane was heated to 65.degree. C. while stirring under a 
nitrogen stream, and 0.7 g of 2,2-azobis(isovaleronitrile) (referred to as 
A. I. V. N.) was then added thereto and reacted for 6 hours. 
After passage of 20 minutes from the addition of the initiator (A. I. V. 
N.), the homogeneous solution became slightly opaque, the reaction 
temperature being raised to 90.degree. C. After cooling, the reaction 
product was passed through a nylon cloth of 200 mesh to obtain a white 
dispersion having an average grain diameter of 0.25 .mu.m as a white 
latex. 
Preparation Example 9 of Resin Grains 
A mixture of 50 g of acrylonitrile, 8 g of Dispersed Resin I (as solid 
content), 1.2 g of divinylbenzene and 200 g of n-hexane was heated to 
55.degree. C. while stirring under a nitrogen stream, and 0.5 g of A. I. 
V. N. was added thereto and reacted for 4 hours, thus obtaining a white 
dispersion. After cooling, the reaction product was passed through a nylon 
cloth of 200 mesh. The resulting dispersion was a latex with an average 
grain diameter of 0.20 .mu.m. 
Preparation Example 10 of Resin Grains 
Preparation Example 8 was repeated except using a mixture of 50 g of 
N-vinylpyrrolidone, 10 g of Dispersed Resin (as solid content), 1.5 g of 
ethylene glycol dimethacrylate and 200 g of toluene, thus obtaining a 
white latex with an average grain size of 0.30 .mu.m. 
Preparation Example 11 of Resin Grains 
A mixture of 31.5 g of ethylene glycol, 51.8 g of phthalic anhydride, 6.0 g 
of methacrylic acid, 10 g of trichloroethylene and 0.7 g of 
p-toluenesulfonic acid was heated and reacted for 6 hours in such a manner 
that the reaction temperature was raised from 107.degree. C. to 
150.degree. C. in 6 hours, while removing water byproduced by the reaction 
by the Dean-Stark method. 
A mixture of 6 g of methacrylic acid,0.05g of 1,6-hexanediol diacrylate, 76 
g of chloroform, 11.6 g of ethanol and 5.8 g (as solid content) of 
Dispersed Resin I was then refluxed under a nitrogen stream. 0.8 g of A. 
I. B. N. was then added thereto and reacted for hours to obtain a white 
dispersion, latex with an average grain diameter of 0.45 .mu.m. 
Preparation Example 12 of Resin Grains 
Preparation Example 8 was repeated except using a mixture of 50 g of 
N,N-dimethylaminoethyl methacrylate, 0.8 g of triethylene glycol 
dimethacrylate, 15 g of poly(dodecyl methacrylate) and 300 g of toluene, 
thus obtaining a white dispersion with an average grain diameter of 0.43 
.mu.m. 
Preparation Example 13 of Resin Grains 
A mixed solution of 50 g of the following Monomer A, 30 g of methyl 
methacrylate, 17 g of 2-hydroxyethyl methacrylate, 3 g of allyl 
methacrylate and 300 g of tetrahydrofuran was heated to 80.degree. C. 
under a nitrogen stream. 1.5 g of A.I.B.N. was added thereto, reacted for 
6 hours and then subjected to reprecipitation in n-hexane. A solid product 
was collected by filtering and dried to obtain 84 g of a powder. 
##STR23## 
Preparation Example 14 of Resin Grains 
A mixture of 50 g of (2-hydroxypropyl methacrylate/ethyl methacrylate) 
copolymer (weight component ratio 1/3) and 200 g of methyl cellosolve was 
heated to 40.degree. C. to prepare a solution, to which 1.0 g of 
1,6-hexamethylene diisocyanate was added and stirred for 4 hours. The 
mixture was cooled, subjected to reprecipitation in water and a solid 
product was then collected by filtration, followed by drying to obtain 35 
g of a powder. 
Preparation Example 15 of Resin Grains 
A mixture of 5 g of 2-methyl-2 oxazoline, 1.0 g of 
1,4-tetramethylene-2,2'-bisoxazoline, 0.1 g of boron trifluoride in the 
form of ether solution and 20 g of acetonitrile was subjected to sealing 
polymerization at 100.degree. C. for 7 hours. The thus resulting reaction 
product was subjected to reprecipitation in methanol and a solid product 
was obtained by filtration, followed by drying to obtain 4.1 g of a 
powder. 
The resin (hydrogel) obtained in this Preparation Example has the following 
structure: 
##STR24## 
Preparation Example 16 of Resin Grains 
A mixed solution of 50 g of 2-methanesulfonylethyl methacrylate, 0.8 g of 
divinylsuccinic acid and 200 g of dimethylformamide was heated to 
70.degree. C. under a nitrogen stream, and 1.5 g of A. I. B. N. was added 
thereto and reacted for 8 hours. The resulting reaction product was then 
subjected to reprecipitation in hexane and a solid product was collected 
by filtration, followed by drying to obtain 38 g of a powder. 
Example 14 
A mixture of 200 g of photoconductive zinc oxide, 40 g of (ethyl 
methacrylate/acrylic acid) copolymer (weight component ratio 97/3, weight 
average molecular weight 63,000), 1.5 g (as solid content) of the resin 
grains obtained in Preparation Example 1, 0.06 g of Rose Bengal, 0.20 g of 
phthalic anhydride and 300 g of toluene was ball milled for 2 hours. The 
thus resulting light-sensitive layer forming dispersion was applied to a 
paper rendered electrically conductive to give an adhered quantity on dry 
basis of 25 g/m.sup.2 by a wire bar coater, followed by drying at 
110.degree. C. for 30 seconds. The thus coated paper was allowed to stand 
in a dark place at a temperature of 20.degree. C. and a relative humidity 
of 65% for 24 hours to prepare an electrophotographic light-sensitive 
material. 
Comparative Example 3 
The procedure of Example 14 was repeated except not using 1.5 g (as solid 
content) of the resin grains obtained in Preparation Example 8 to prepare 
an electrophotographic light-sensitive material. 
These light-sensitive materials were then subjected to evaluation of the 
electrostatic characteristics and reproduced image quality, in particular, 
under ambient conditions of 30.degree. C. and 80% RH. Furthermore, when 
using these light-sensitive materials as master plate for offset printing, 
the oil-desensitivity of the photoconductive layer in terms of a contact 
angle of the photoconductive layer with water after oil-desensitization 
and the printing performance in terms of a stain resistance and printing 
durability. 
The image quality and printing performance were evaluated using a 
lithographic printing plate obtained by subjecting the light-sensitive 
material to exposure and development by means of an automatic plate making 
machine, ELP 404 V using a developing agent, ELP-T to form an image and 
etching by means of an etching processor using an oil-desensitizing 
solution, ELP-E. As a printing machine, Hamada Star 800 SX was used. 
The results are shown in Table 6: 
TABLE 6 
______________________________________ 
Comparative 
Example 14 
Example 3 
______________________________________ 
Electrostatic 
Characteristics 
Vo (-V) 580 555 
DRR (%) 83 88 
E.sub.1/10 (lux .multidot. sec) 
11.0 11.5 
Image Quality 
I: (20.degree. C., 65%) 
good good 
II: (30.degree. C., 80%) 
good good 
Contact Angle with 
less than 5.degree. 
40-50.degree. 
Water (degrees) large dispersion 
Background stain 
I no yes 
II no marked 
Printing no stain even 
marked background 
Durability after 10000 
stain from 
prints printing start 
______________________________________ 
The characteristic items described in Table 6 are evaluated as described in 
the notes of Table 2. 
As can be seen from Table 6, the light-sensitive material of the present 
invention exhibited excellent electrostatic characteristics of the 
photoconductive layer and gave a reproduced image free from background fog 
and excellent in image quality. This tells that the photoconductive 
material and binder resin are sufficiently combined and the added 
hydrophilic resin grains have no bad influences upon the electrostatic 
characteristics. 
When the light-sensitive material of the present invention is used as a 
master plate for offset printing, the oil-desensitizing processing can 
well be accomplished by one passage through a processor even with a 
diluted oil-desensitizing solution and consequently, a non-image area is 
so rendered hydrophilic that the contact angle of the non-image area with 
water be smaller than 10.degree. . Thus, it is found by observation of 
real prints that the printing plate precursor of the present invention can 
form a clear image and produce more than 10,000 clear prints without 
background stains. 
In Comparative Example 3, on the other hand, the electrophotographic 
properties (image quality) were good, but in the oil-desensitizing 
processing as a master plate for offset printing, a non-image area was not 
sufficiently rendered hydrophilic, so that in real printing, background 
fog markedly occurred from the beginning in the print. 
It will clearly be understood from these considerations that according to 
only the present invention, there can be obtained an electrophotographic 
photoreceptor capable of satisfying electrostatic properties as well as 
printing adaptability. 
Examples 15 to 18 
The procedure of Example 14 was repeated except using 1.5 g (as solid 
content) of each of the resin grains shown in Table 7 instead of the resin 
grains obtained in Preparation Example 8, thus obtaining each of 
electrophotographic light-sensitive materials. 
These light-sensitive materials were subjected to the similar evaluations 
to Example 14 to obtain results as shown in Table 7: 
TABLE 7 
______________________________________ 
Contact Number of 
Hydrophilic 
Image Angle Printing 
Example 
Resin Grains 
Quality with Water 
Durability 
______________________________________ 
15 Preparation 
excellent in 
11.degree. 
more than 
Example 9 and II of 10,000 prints 
Table 6 free from 
stains 
16 Preparation 
excellent in 
9.degree. 
more than 
Example 10 and II of 10,000 prints 
Table 6 free from 
stains 
17 Preparation 
excellent in 
5.degree. or less 
more than 
Example 11 and II of 10,000 prints 
Table 6 free from 
stains 
18 Preparation 
excellent in 
5.degree. or less 
more than 
Example 12 and II of 10,000 prints 
Table 6 free from 
stains 
______________________________________ 
As can be seen from the results of Table 7, the electrophotographic 
photoreceptor of the present invention has excellent electrophotographic 
properties and is capable of giving a number of clear prints free from 
background stain. 
Example 19 
A mixture of 10 g of the resin powder obtained by Preparation Example 16, 
1.8 g of (dodecyl methacrylate/acrylic acid) copolymer (weight component 
ratio 95/5) and 100 g of toluene was dispersed for 56 hours in a ball mill 
to obtain a dispersion, i.e., latex with an average grain diameter of 0.40 
.mu.m. 
A light-sensitive material was prepared in an analogous manner to Example 
14 except using 1.5 g of the thus resulting resin grains (as solid 
content) and subjected to measurement of the electrostatic 
characteristics, image quality and printing properties. The image quality 
was good and the contact angle of non-image areas after etching with water 
was small, i.e. 6.degree.. In printing, there was found no background 
stain from the start of printing, nor background stain even after printing 
10,000 prints. 
Examples 20 to 22 
The procedure of Example 19 was repeated except using 10 g of each of the 
resin grains shown in the following Table 8 instead of the resin grains 
obtained in Preparation Example 16, thus obtaining each of light-sensitive 
materials. 
TABLE 8 
______________________________________ 
Average Grain Number of 
Diameter Image Printing 
Example 
Resin Grains 
of Latex quality 
Durability 
______________________________________ 
20 Preparation 
0.35 .mu.m good more than 
Example 13 10,000 prints 
free from 
stains 
21 Preparation 
0.41 .mu.m good more than 
Example 14 10,000 prints 
free from 
stains 
22 Preparation 
0.33 .mu.m good more than 
Example 15 10,000 prints 
free from 
stains 
______________________________________ 
These light-sensitive materials were subjected to measurement of the 
electrostatic characteristics and printing properties in the similar 
manner to Example 14, thus resulting in good results as shown in Table 8. 
In printing, in particular, there was found no background stains in a 
print even after printing 10,000 prints. 
Examples 23 to 29 
The procedure of Example 14 was repeated except using the same amount of 
each of resin powders shown in Table 9 instead of the resin grains 
obtained in Preparation Example 8, thus obtaining each of light-sensitive 
materials. 
These light-sensitive materials were subjected to measurement of the 
electrostatic characteristics and printing properties in the similar 
manner to Example 14, thus obtaining good results as shown in Table 9. In 
printing, in particular, there was found no background stain in a print 
even after printing 10,000 prints. 
TABLE 9 
__________________________________________________________________________ 
Number of 
Image 
Printing 
Example 
Resin Grains* 
Main Component 
Quality 
Durability 
__________________________________________________________________________ 
23 Turfin P-20 
Polyacrylic acid 
good 
more than 
(Kao KK) 10,000 prints 
free from stains 
24 KI Gel KI201K 
isobutylene/ 
good 
more than 
(Kurare Isoprene 
maleic anhydride 
10,000 prints 
Chemical) copolymer free from stains 
saponified 
25 Sumika Gel SP-510 
acrylic acid/ 
good 
more than 
(Sumitomo Kagaku 
vinyl alcohol 
10,000 prints 
KK) copolymer free from stains 
26 Sumika Gel NP-1010 
sodium poly- 
good 
more than 
(Sumitomo Kagaku 
acrylate 10,000 prints 
KK) free from stains 
27 Aquaprene L-710 
polyethylene 
good 
more than 
(Meisei Kagaku KK) 
oxide 10,000 prints 
free from stains 
28 Sanwet IM-300 MPS 
starch poly- 
good 
more than 
(Sanyo Kasei KK) 
acrylate 10,000 prints 
free from stains 
29 G. P. C. (Grain 
starch/acrylo- 
good 
more than 
Processing Co.) 
nitrile copolymer 
10,000 prints 
saponified free from stains 
__________________________________________________________________________ 
Note: *commercial name 
As is evident from the results of these Examples, the hydrophilic resin of 
the present invention can sufficiently be dispersed in the form of desired 
fine particles even by a method comprising adding the hydrophilic resin in 
the form of a powder to a zinc oxide light-sensitive layer forming 
composition without previous formation of fine particles and then 
subjecting the resin powder containing composition to dispersing treatment 
in a ball mill. 
According to the present invention, therefore, there can be provided a 
lithographic printing plate precursor with very excellent printing 
properties. 
Since the hydrophilic resin grains of the present invention do not 
deteriorate the electrophotographic properties of the photoconductive 
layer, it is possible to effect formation of an image with a good image 
quality and to speed up the processings of from etching to printing. 
The hydrophilic resin having a high order network structure according to 
the present invention has also the similar merits. Furthermore, this 
hydrophilic resin grains is insoluble or hardly soluble in water and is 
not dissolved out with moistening water during lithographic printing, so 
not only the number of prints can be increased, but also the lithographic 
printing plate can repeatedly be used in stable manner.