JPS63220149A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain excellent electrostatic characteristics and to permit reproduction of a copied image faithful to an original picture by incorporating at least two kinds of a resin contg. specific acidic groups and resin contg. an OH group and/or basic group into a binder resin. CONSTITUTION:The binder resin is constituted of the resin which contains 0.05-20wt.% copolymer component having 10<3>-10<4> weight average mol.wt. and contg. at least one kind of the acidic groups selected from a -PO3H group, -COOH group and -SO3H group and the resin which contains 0.05-15wt.% copolymer component having 10<4>-3X10<5> weight average mol.wt. and contg. OH group and/or basic group. The electrophotographic sensitive material having the performances which are excellent in the smoothness and strength of the photoconductive layer, the electrostatic characteristics and image pickup characteristic is thereby obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor having excellent electrostatic properties, moisture resistance, and durability.

(Prior Art) Electrophotographic photoreceptors have various configurations in order to obtain predetermined characteristics or depending on the type of electrophotographic process to which they are applied.

As representative electrophotographic photoreceptors, there are photoreceptors having a photoconductive layer formed on a support and photoreceptors having an insulating layer on the surface, which are widely used. Photoreceptors comprising a support and at least one photoconductive layer are used for image formation by most common electrophotographic processes, ie, charging, image exposure and development, and optionally transfer.

Furthermore, a method of using an electrophotographic photoreceptor as an offset original plate for direct plate making is widely used.

The binder used to form the photoconductive layer of the electrophotographic photoreceptor has excellent film-forming properties itself and the ability to disperse photoconductive powder into the binder, and the formed recording layer The photoconductive layer of the recording layer has good adhesion to the substrate, and the photoconductive layer of the recording layer has excellent charging ability, has low dark decay, large light decay, and low pre-exposure fatigue, and is easily resistant to changes in humidity during imaging. It is necessary to have various electrostatic properties such as the need to stably maintain these properties and excellent imaging performance.

Examples of resins that have been known for a long time include silicone resin (Japanese Patent Publication No. 34-6670), styrene-butadiene resin (
(Special Publication No. 35-1960), alkyd resin 1, maleic acid resin, polyamide (Special Publication No. 11219/197),
Vinyl acetate resin (Japanese Patent Publication No. 41-2425), vinyl acetate copolymer (Japanese Patent Publication No. 41-2426), acrylic resin (Japanese Patent Publication No. 35-11216), acrylic ester copolymer (e.g. Japanese Patent Publication No. 11219/1989) No., Special Publication No. 1977
-8510, Japanese Patent Publication No. 4-1-13946, etc.) are known.

However, in electrophotographic photosensitive materials using these resins, 1) the affinity with the photoconductive powder is insufficient, resulting in poor dispersibility of the coating liquid, and 2) the charging property of the photoconductive layer is poor. low, 3
) The quality of the image area of the copied image (especially halftone reproducibility and resolution) is poor; 4) The environment at which the copied image was created (e.g. high temperature,
5) The film strength and adhesion of the photosensitive layer are not sufficient, especially when used as an offset master, the photosensitive layer may come off during offset printing, making it impossible to print a large number of sheets. , etc. There was one of the problems.

Various methods have been proposed to improve the electrostatic properties of the photoconductive layer, and one such method includes the use of a compound containing a carboxyl group or a nitro group in an aromatic ring or a furan ring, or a dicarboxylic acid anhydride. further combined,
A method of coexisting in the photoconductive layer is disclosed in Japanese Patent Publication No. 42-6878,
It is disclosed in Japanese Patent Publication No. 45-3073. However, even with the photosensitive materials improved by these methods, their electrostatic properties are still insufficient, and none particularly excellent in light attenuation properties has been obtained. Therefore, in order to improve the lack of sensitivity of this photosensitive material, a method of adding a large amount of sensitizing dye to the photoconductive layer has been conventionally used, but the whiteness of the photosensitive materials produced by this method deteriorates significantly. However, there is a problem in that the quality of the recording medium deteriorates, and in some cases, the dark decay of the photosensitive material deteriorates, making it impossible to obtain a sufficient copy image.

On the other hand, JP-A-60-10254 discloses a method of adjusting the average molecular weight of a resin used as a binder resin for a photoconductive layer. That is, an acrylic resin with an acid value of 4 to 50 and an average molecular weight distribution of 104 to 104;
A technique is described in which electrostatic properties (particularly good repeatability as a PPC photoreceptor), moisture resistance, etc. are improved by using together components having a distribution of 4 to 2×10 4 .

Furthermore, research is being carried out on lithographic printing original plates using electrophotographic photoreceptors, and a binder resin for the photoconductive layer that has both the electrostatic properties of an electrophotographic photoreceptor and the printing properties of a printing original plate has been developed. For example, in Japanese Patent Publication No. 50-31011, Mwl, 8 to 10
A combination of a resin with a TglO~80°C at O' and a copolymer consisting of a (meth)acrylate monomer and a monomer other than fumaric acid, and JP-A-53-540
In No. 27, a terpolymer containing a (meth)acrylic acid ester having a substituent having a carboxylic acid group separated from an ester bond by at least 7 atoms is used; In JP-A-57-202544, a quaternary or quintuple copolymer containing acrylic acid and hydroxyethyl (meth)acrylate is used, and in JP-A-58-68046, an alkyl group having 6 to 12 carbon atoms is used. It is described that a terpolymer containing a (meth)acrylic ester and a carboxylic acid-containing vinyl monomer as a substituent is effective in improving the desensitization property of the photoconductive layer.

(Problems to be Solved by the Invention) However, even though the resins are said to be effective in the above-mentioned electrostatic properties, moisture resistance properties, and durability, when actually evaluated, they are found to have particularly poor chargeability and dark charge retention. There are problems with electrostatic properties, photosensitivity, smoothness of the photoconductive layer, etc.

It was not practically satisfactory.

Furthermore, even in the case of a binder resin which is said to have been developed as an original plate for electrophotographic lithographic printing, when actually evaluated, there were problems with the above-mentioned electrostatic properties, scumming of printed matter, etc.

The present invention is intended to improve the problems of conventional electrophotographic photoreceptors as described above.

An object of the present invention is to provide a high-quality electrophotographic photoreceptor that has improved electrostatic properties (particularly dark charge retention and photosensitivity) and reproduces copied images that are faithful to original images.

Another object of the present invention is to provide an electrophotographic photoreceptor that produces clear and high-quality images even when the environment during copy image formation varies, such as low temperature and low humidity or high temperature and high humidity.

Another object of the present invention is to provide an original plate for electrophotographic planographic printing.
It has excellent electrostatic properties (particularly dark charge retention and photosensitivity□), reproduces copied images that are faithful to the original, and does not cause not only uniform background stains on the entire surface of printed matter but also dotted background stains. The purpose is to provide a lithographic printing original plate.

(Means for Solving the Problems) The above problem is that in an electrophotographic photoreceptor having a photoconductive layer containing a small amount of both an inorganic photoconductive material and a binder, the binder resin is the following resin [A]. It has been found that the problem can be solved by an electrophotographic photoreceptor having a special feature of containing at least two of the following: and resin [B].

(i) Resin [A] having a weight average molecular weight of 103 to 104, G-PO,
0.05% of the copolymerization component containing at least one acidic group selected from H group, -COOH group and -3o, HW.
Resin containing ~20% by weight (11) Resin [B] having a weight average molecular weight of 104 to 3 x 105, and OH
Copolymerization containing groups and/or basic groups 1 component 0
．． Resin containing 05-15% by weight.

That is, the binder resin provided in the present invention is composed of a low molecular weight resin containing an acidic group [A] and a high molecular weight resin containing an -OH group and/or a basic group [B]. .

The acidic group contained in the resin [A] is -Po2
Examples include H group, -COOH group and/or -3o, H group.

The proportion of the copolymer component containing the acidic group is 0.05 to 20% by weight in the resin [A], more preferably 0.05 to 20% by weight.
It is 5 to 10% by weight. The weight average molecular weight of the resin [A] is 103 to 104, more preferably 3X103 to
It is 9×104.

The glass transition point of the resin [A] is preferably -10°C to 1
00°C, more preferably -5°C to 80°C.

In the resin [B], the proportion of the copolymerized component containing an -OH group and/or a basic group is 0.05 to 15% by weight, more preferably 0.5 to 10% by weight in the resin [B]. It is a heavy weight%. The weight average molecular weight of resin [B] is 104 to 3 x 105
But preferably.

It is 3×10 5 to 10 4 . The glass transition point of the resin [B] is preferably in the range of O''C to 120C, more preferably in the range of 10C to 80C.

In the present invention, the resin [A] adsorbs the acidic groups contained in the resin and the stoichiometric defects of the inorganic photoconductor, and has a low molecular weight, so that the coating property of the surface of the photoconductor is improved. This improves photoconductor trapping and improves humidity properties, while ensuring sufficient photoconductor dispersion and suppressing agglomeration.

Resin [B] is used to sufficiently level out the mechanical strength of the photoconductive layer, which is insufficient when resin (A) alone is used.

If the acidic group content in the resin [A] is less than 0.05% by weight, the initial potential will be low and sufficient image density cannot be obtained; on the other hand, if the acidic group content is more than 20% by weight, Dispersibility is lowered, film smoothness and high-temperature electrophotographic properties are lowered, and when used as an offset master, background smearing is increased, which is undesirable.

In the present invention, the 10H group component or basic group component in the resin [B] has a weak interaction with the photoconductor particle interface and the resin [A], and stabilizes the dispersion of the photoconductor dispersion. It is thought that it has the effect of increasing the strength of the film after it is formed. However, if the proportion of these components in the resin [B] exceeds 15% by weight, the photoconductive layer will be affected by moisture and the moisture resistance of the photoconductive layer will decrease.

Furthermore, even when only the low molecular weight resin [A] in the present invention is used as the binder resin, the photoconductor and the binder resin can sufficiently adsorb and coat the particle surface, resulting in a smooth photoconductive layer. Although it is possible to obtain image quality that is good in terms of electrostatic properties and electrostatic properties and is free from background smudges, the film strength is still insufficient and satisfactory results cannot be obtained in terms of durability.

On the other hand, even when the electrophotographic photoreceptor of the present invention is used as an original plate for electrophotographic lithographic printing, the surface smoothness of the photoconductor layer is good, and the zinc oxide particles as the photoconductor are contained in the binder. Because it is sufficiently dispersed, when it is desensitized using a fat-free treatment liquid, the non-image area is made uniformly and sufficiently hydrophilic, and the adhesion of printing ink to the non-image area during printing is suppressed. Even if a large number of prints are printed, scumming will not occur.

For both the resin [A] and the resin (Bl), conventionally known resins can be used as long as they have the physical properties described above. For example,
Polyester resin, modified epoxy resin, silicone resin, polycarbonate resin, vinyl alkanoate resin, modified polyamide resin, phenol resin, fatty acid modified resin, acrylic resin, maleic anhydride resin, acrylic resin, etc. are used.

More specifically, as an example of resin [A], a (meth)acrylic copolymer containing a total amount of 30% by weight or more of a monomer represented by the following general formula (I) as a copolymer component can be mentioned.

General formula (I) CH, -C Coo-R' -S In formula (I), represent.

-R″ is an optionally substituted alkyl group having 1 to 18 carbon atoms (e.g., methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, octyl group, decyl group, dodecyl group, tridecyl group) group, tetradecyl group, 2-
methoxyethyl group, 2-ethoxyethyl group, 2-chloroethyl group), optionally substituted alkenyl groups having 2 to 18 carbon atoms (e.g. vinyl group, allyl group, isopropenyl group, butenyl group, hexenyl group, heptenyl group,
octenyl group, etc.), an optionally substituted aralkyl group having 7 to 12 carbon atoms (e.g. benzyl group, phenethyl group,
methoxybenzyl group, ethoxybenzyl group, methylbenzyl group, etc.), optionally substituted cycloalkyl groups having 5 to 8 carbon atoms (e.g., cyclopentyl group, cyclohexyl group, cycloheptyl group, etc.), aryl groups (e.g., phenyl group) , tolyl group, xyl group, mesityl group, naphthyl group, methoxyphenyl group, ethoxyphenyl group, chlorophenyl group, dichlorophenyl group, etc.).

The "acidic group-containing copolymer component" contained in the resin [A] of the present invention may be any vinyl compound containing an acidic group that can be copolymerized with general formula (1). For example, it is described in "Polymer Data Handbook [Basic Edition]" edited by the Society of Polymer Science and Technology, Baifukan (1986). Specifically, acrylic acid α- and/or β-substituted acrylic acid (
For example, α-acetoxy form, α-acetoxymethyl form, α
-(2-niaminomethyl form), α-chloro form, α-bromo form, α-chloro form, α-tributylsilyl form, α-cyano form, β-chloro form, β-bromo form, α-chloro-β-
methoxy form, α, β-dichloro form, etc.), methacrylic acid,
Itaconic acid, itaconic acid half esters, itaconic acid half amides, crotonic acid, 2-alkenylcarboxylic acids (e.g. 2-pentenoic acid, 2-methyl-2-hexenoic acid,
-octenoic acid, 4-methyl-2-hexenoic acid, 4-ethyl-2-octenoic acid, etc.), maleic acid, maleic acid half esters, maleic acid half amides, vinylbenzenecarboxylic acid, vinylbenzenesulfonic acid, vinyl Examples include half-ester derivatives of vinyl or allyl groups of sulfonic acid, vinylphosphonic acid, and dicarboxylic acids, and compounds containing the acidic group in the substituent of these carboxylic acids or sulfonic acid ester derivatives and amide derivatives. .

In addition, the "copolymer component containing r-OH group and/or basic group" contained in the resin [B] is a vinyl compound containing the substituent that can be copolymerized with -a formula (1). The basic group may be any basic group as long as it has the general formula (n
) and a nitrogen atom-containing heterocyclic group.

General formula (n) In formula (n), R1 and R2 may be the same or different, and each represents a hydrogen atom, an optionally substituted alkyl group (e.g., methyl group, ethyl group, propyl group, butyl group, hexyl group). , octyl group, decyl group, dodecyl group, tetradecyl group, octadecyl group, 2-chloroethyl group, 2-bromoethyl group, 2-chloroethyl group, 2-hydroxyethyl L2-cyanoethyl group, 2-methoxyethyl group, 3-ethoxypropyl group groups, etc.), optionally substituted alkenyl groups (e.g. allyl group, isopropenyl group, 4-butynyl group, etc.), optionally substituted aralkyl groups (e.g. benzyl group, phenethyl group) LTs, chlorobenzyl group, methyl benzyl group, methoxybenzyl group, hydroxybenzyl group, etc.), alicyclic group (e.g. cyclopentyl group, cyclohexyl group, etc.), aryl group (e.g. phenyl group, tolyl group, xylyl group, mesityl group, butylphenyl group, methoxyphenyl group) Furthermore, R8 and R2 may be connected via a hydrocarbon group, which may be via a hetero atom.

Furthermore, as a nitrogen atom-containing heterocycle, 1 to 3 nitrogen atoms are used.
Examples include heterocycles consisting of a 5- to 7-membered ring containing 5- to 7-membered rings, and these heterocycles may further form a condensed ring with a benzene ring, a naphthalene ring, etc. Furthermore, these rings may have a substituent. Specifically, for example, a pyrrole ring, an imidazole ring, a pyrazole ring, a pyridine ring, a piperazine ring, a pyrimidine ring, a pyridazine ring, an indolizine ring, an indole ring, a 2H-pyrrole ring, a 3H-indole ring. , indazole ring, purine ring, monoline ring,
Isoquinoline ring, phthalazine ring, naphthyridine ring, quinoxazine ring, acridine ring, phenanthridine ring, phenazine ring, pyrrolidine ring, pyrroline ring, imidazolidine ring, imidacilline ring, pyrazolidine ring, pyrazoline ring,
Piperidine ring, piperazine ring, quinacridine ring, indoline ring, 3,3-dimethylindolenine ring, 3,3-dimethylnaphthoindolenine ring, thiazole ring, benzothiazole ring, naphthothiazole ring, oxazole ring, benzoxazole ring, naphtho Examples include an oxazole ring, a selenazole ring, a benzoselenazole ring, a naphthoselenazole ring, an oxazoline ring, an isoxazole ring, a benzoxazole ring, a morpholine ring, a pyrrolidone ring, a triazole ring, a benzotriazole ring, and a triazine ring.

These OH groups and/or basic groups can be used in the resin [
A desired monomer can be obtained by incorporating it into a substituent of an ester derivative or amide derivative derived from a vinyl group-containing carboxylic acid or sulfonic acid, as exemplified in the acidic group-containing vinyl compound in A]. . For example, 2-hydroxyethyl methacrylate, 3-hydroxypropyl methacrylate, 3-hydroxy-2-chloromethacrylate, 4-hydroxybutyl methacrylate, 6-hydroxyhexyl methacrylate, 10-hydroxydecyl methacrylate, N-(2-hydroxyethyl) Acrylamide, N-(3-hydroxypropyl)methacryamide, N-(α.

α-dihydroxymethyl)ethylmethacryamide, N-
(4-hydroxybutyl)methacryamide, N, N-
Dimethylaminoethyl methacrylate, 2-(N,N-
diethylaminoethyl) methacrylate, 3-(N,N
-dimethylpropyl) methacrylate, 2-(N,N-
(dimethylethyl) methacrylamide hydroxystyrene, hydroxymethylstyrene, N,N-dimethylaminomethylstyrene, N,N-diethylaminomethylstyrene, N-butyl-N-methylaminomethylstyrene, N-(hydroxyphenyl)methacrylamide, etc. Examples include monomers such as As the vinyl compound having a nitrogen atom-containing heterocycle, for example, the above-mentioned "Polymer Data Handbook [Basic Edition]" pp. 175-181, D,
A. Tomalia.

rReactive Heteracyclic Mo
Chapter 1 of “Function”
nal Monomers Vol, 2”, Marc
el DeRRetInc, N, '1. (197
4), L, S, Lu5Rin, rBasicM
onoa+ersJchap 3 of ”Funct
ional Monoa+ersVo12”, Mar
cel DeRRer Inc, N, Y, (19
74) and the like.

Furthermore, the resin [A] and the resin [B] of the present invention may contain other monomers as copolymerization components together with the above-mentioned monomers. For example, α-olefins, alkanes, etc. Examples include acid vinyl or allyl esters, acrylonitrile, methacrylnitrile, vinyl ethers, acrylamides, methacrylamides, styrenes, heterocyclic vinyls (eg, vinylthiophene, vinyl-dioxane, vinyl-oxazine, etc.).

Furthermore, in addition to the resins (Al and [B]) of the present invention, other resins can also be used in combination. Examples of these resins include alkyd resins, polybutyral resins, polyolefins, ethylene-vinyl acetate copolymers, etc. , styrene resin,
Examples include styrene-butadiene resin, acrylate-butadiene resin, vinyl alkanoate resin, and the like.

Resins other than these resins [A] and [B] account for 30% (weight ratio) of the total amount of binder resin containing the resin of the present invention.
If it exceeds this value, the effects of the present invention (especially improvement in electrostatic and electrical properties) will be lost.

The ratio of the amounts of resin [A] and [B] used in the present invention varies depending on the type, particle size, and surface condition of the inorganic photoconductive material used, but in general, the ratio of resin [A] and resin [B] used is The ratio is 5 to 80 to 95 to 20 (weight ratio), preferably 15 to 60 to 85 to 40 (weight ratio).

Further, the weight average molecular weight ratio of resin [A] and resin [B] is 1.
It is preferably 2 or more, more preferably 2° or more.

Inorganic photoconductive materials used in the present invention include zinc oxide,
Examples include titanium oxide, zinc sulfide, cadmium sulfide, cadmium carbonate, zinc selenide, cadmium selenide, tellurium selenide, lead sulfide, and the like.

The total amount of binder resin used for the inorganic photoconductive material is 10 to 100 parts by weight, preferably 15 to 50 parts by weight, per 100 parts by weight of the photoconductor.

In the present invention, various dyes can be used in combination as spectral sensitizers if necessary. For example, Harumi Miyamoto, Hidehiko Takei, Imaging 1973 (Nα8) p. 12, C, J
, Young etc.+RCA Review 1dan, 4
69 (1954), Wataru Kiyota, Transactions of the Institute of Electrical Communication Engineers J63-C (Shu 2), 97 (1980), Yuji Harasaki et al., Journal of Industrial Chemistry 66 78 and 188 (1963)
), Tadaaki Tani 1 Journal of the Photographic Society of Japan, Kodan.

Carbonium dyes, diphenylmethane dyes, triphenylmethane dyes, cited in reviews such as 20B (1972), etc.
Examples include xanthine dyes, phthalein dyes, polymethine dyes (for example, oxonol dyes, merocyanine dyes, cyanine dyes, logocyanine dyes, styryl dyes, etc.), phthalocyanine dyes (which may contain metals), and the like.

More specifically, examples of those mainly using carbonium dyes, triphenylmethane dyes, xanthine dyes, and phthalein dyes include Japanese Patent Publication No. 452/1983, Japanese Patent Application Laid-open No. 90334/1983, and Japanese Patent Application Laid-Open No. 50-90334. -114227, JP 53-39130, JP 53-82353,
U.S. Patent No. 36052.540, U.S. Patent No. 4. 0
54. 450, JP-A-57-16456, and the like.

oxonol dye, merocyanine dye, cyanine dye,
Polymethine dyes such as logcyanine dyes include F,
M, Hammer rThe Cyanine D
yes and Related Compounds
J. et al., and more specifically, U.S. Pat. No. 3,047.384, U.S. Pat. No. 3,1
No. 10.591, U.S. Pat. No. 3.121,008, U.S. Pat. No. 3.125.447, U.S. Pat. 12
8. No. 179, U.S. Patent No. 3,132,942, U.S. Patent No. 3,622,317, British Patent No. 1,226
．． No. 892, British Patent No. 1,309,274, British Patent No. 1,405,898, Japanese Patent Publication No. 1978-7814,
Examples include dyes described in Japanese Patent Publication No. 55-18892.

Furthermore, as a polymethine dye that spectrally sensitizes the near-infrared to infrared light region with a long wavelength of 700 nm or more, JP-A-47-84
No. 0, JP-A No. 47-44180, JP-A No. 51-410
No. 61, JP-A-49-5034, JP-A-49-451
No. 22, JP-A-57-46245, JP-A-56-35
No. 141, JP-A-57-157254, JP-A-61-
No. 26044, JP-A No. 61-27551, U.S. Patent No. 3゜619.154, U.S. Patent No. 4,175.956
No., rResearch Disclosure J
1982, 216, pp. 117-118. The photoreceptor of the present invention is excellent in that its performance does not easily vary depending on the sensitizing dye, even when various sensitizing dyes are used together. Furthermore, if necessary, various conventionally known additives for electrophotographic photosensitive layers such as chemical sensitizers can be used in combination. For example, the above-mentioned review; Imaging 1973 (Na8), p. 12, references to electron-accepting compounds (e.g., halogens, benzoquinone, chloranil, acid anhydrides, etc.), Hiroshi Komon et al., "Recent photoconductive materials and photosensitive Examples include polyarylalkane compounds, hindered phenol compounds, p-phenylenediamine compounds, etc. cited in the review of ``Development and Practical Application of Phytochemistry,'' Chapters 4 to 6, Nihon Kagaku Information Co., Ltd. Publishing Department (1986). .

The amount of these various additives added is not particularly limited, but
Usually 0°0001 to 2.00% per 100 parts by weight of photoconductor.
It is 0 parts by weight.

The thickness of the photoconductive layer is preferably 1-100 .mu.m, particularly 10-50 .mu.m.

In addition, when a photoconductive layer is used as a charge generation layer in a laminated photoreceptor consisting of a charge generation layer and a charge transport layer, the thickness of the charge generation layer is 0.01 to 1μ, particularly 0.05 to 0.5μ. suitable.

In some cases, an insulating layer is added mainly for the purpose of protecting the photoreceptor, improving its durability, dark decay characteristics, etc.

At this time, the insulating layer is set relatively thin, and when the photoreceptor is used for a specific electrophotographic process, the insulating layer provided is set relatively thick.

In the latter case, the thickness of the insulating layer is between 5 and 70μ, in particular 1
It is set to 0 to 50μ.

Charge transport materials for the laminated photoreceptor include polyvinylcarbazole, oxazole dyes, pyrazoline dyes, triphenylmethane dyes, and the like.

The thickness of the charge transport layer is 5 to 40μ, particularly 1O to 3
0μ is suitable.

Typical resins used to form the insulating layer or charge transport layer include polystyrene resin, polyester resin, cellulose resin, polyether resin, vinyl chloride resin, vinyl acetate resin, vinyl chloride vinyl oxide copolymer resin, Thermoplastic resins and curable resins such as polyacrylic resins, polyolefin resins, urethane resins, polyester resins, epoxy resins, melamine resins, and silicone resins are used as appropriate.

The photoconductive layer according to the invention can be provided on a conventionally known support. Generally speaking, the support for the electrophotographic photosensitive layer is preferably electrically conductive.As the electrically conductive support, for example, a base material such as metal, paper, or plastic sheet impregnated with a low-resistance substance is used in the same manner as in the past. those that have been subjected to conductive treatment, such as those coated with at least lli for the purpose of imparting conductivity to the back surface of the substrate (the surface opposite to the surface on which the photosensitive layer is provided) and further preventing curling; , a water-resistant adhesive layer is provided on the surface of the support, at least one precoat layer is provided on the surface layer of the support as required, A! A material made by laminating electrically conductive plastic onto paper or the like can be used.

Specifically, examples of conductive substrates or conductive materials include:
Yukio Sakamoto, electronic photography, 14. (Nα1).

22-11 (1975), Hiroyuki Moriga, "Introductory Chemistry of Special Papers" Kobunshi Publishing (1975), M, F.

11over, J, Macromol, Set
, Chew, A 4 (6) + No. 1327-1
417 (1970) etc. is used.

(Example) Although embodiments of the present invention are illustrated below, the content of the present invention is not limited thereto.

Synthesis Example 1 A mixed solution of 95 g of ethyl methacrylate, 5 g of acrylic acid and 200 g of toluene was heated to a temperature of 90''C under a nitrogen stream, and then 6 g of 2,2°-azobis(2,4-dimethylvaleronitrile) was added. The reaction was allowed to proceed for 10 hours.

The weight average molecular weight of the obtained copolymer [A]-1 was 780
The glass transition point was 45°C.

Synthesis Example 2 A mixed solution of 95 g of n-butyl methacrylate, 5 g of 2-hydroxyethyl methacrylate, and 200 g of toluene was heated to a temperature of 70°C under a nitrogen stream, and then 0.5 g of azobisisoprotylonitrile was added and reacted for 10 hours. Ta. The weight average molecular weight of the obtained copolymer [B]-1 was 62
000 and the glass transition point was 48°C.

Synthesis Example 3 A mixed solution of 94 g of ethyl methacrylate, 6 g of acrylic acid, and 200 g of toluene was heated to 70°C under a nitrogen stream, and then 0.5 g of azobisisobutyronitrile was added and reacted for 10 hours. . The weight average molecular weight of the obtained copolymer [B]-2 was 60,000.

Synthesis Example 4 A mixed solution of 97 g of ethyl methacrylate, 3 g of acrylic acid, and 200 g of toluene was heated to a temperature of 70° C. under a nitrogen stream, and then 0.5 g of azobisisobutyronitrile was added and reacted for 10 hours. The weight average molecular weight of the obtained copolymer [B]-3 was 61,000.

Example 1 10g (as solid content) of resin [A]-1 produced in Synthesis Example 1, 30g of resin [B]-1 produced in Synthesis Example 2
A photosensitive layer-forming product was prepared by dispersing a mixture of 200 g of zinc oxide, 0.05 g of rose bengal, and 300 g of toluene (as solid content) in a ball mill for 2 hours. An electrophotographic light-sensitive material was prepared by coating with a wire bar so as to give a weight of 22 g/rrf, drying at 110° C. for 1 minute, and then standing in a dark place at 20° C. and 65% RH for 24 hours.

Comparative Example A Resin [A]-1 used as binder resin in Example 1
And instead of [B]-1, only resin [A]-1 was used at 40%
Electrophotographic material A was produced in the same manner as in Example 1 except that g (as solid content) was used.

Comparative Example B Electrophotographic light-sensitive material B was produced in the same manner as in Example 1, except that 40 g (in terms of solid content) of only Resin [B]-2 produced in Synthesis Example 3 was used as the binder resin.

Comparative Example C An electrophotographic material C was produced in the same manner as in Example 1, except that 40 g (in terms of solid content) of only Resin [B]-3 produced in Synthesis Example 4 was used as the binder resin.

Comparative Example An electrophotographic light-sensitive material was produced in the same manner as in Example 1, except that 40 g (in terms of solid content) of Resin [B]-1 produced in Synthesis Example 2 was used as the binder resin.

Film properties (surface smoothness), film strength,
Electrostatic properties, imaging performance, and environmental conditions at 30°C, 280%RH
We investigated the imaging performance when Furthermore, when these photosensitive materials are used as original plates for offset masters, the photoconductive desensitization property (represented by the contact angle with water of the photoconductive layer after desensitization treatment) and printability (background smudge, Rigidity resistance, etc.) were investigated.

Imaging properties and printability were determined by exposing and developing the image using a fully automatic plate making ELP404■ (Fuji Photo Film side type) using developer ELP-T.
The test was carried out using a lithographic printing plate obtained by etching with an etching processor using E.

The above results are summarized in Table-1.

121 The implementation aspects of the evaluation items shown in Table-1 are as follows.

Note 1) Smoothness of photoconductive layer: The obtained photosensitive material was tested using a Beck smoothness tester (Kumagai Riko ■
The smoothness (
Sec/cc) was measured.

Note 2) Mechanical strength of the photoconductive layer: The surface of the photosensitive material obtained was measured using Hayton-14 type surface property test material (manufactured by Shinsha Kagaku Co., Ltd.) and emery paper (#1000) with 50 g/c + IT material. Removal of abrasion powder by repeated rubbing 1000 times, and the remaining film rate (%) from the weight loss of the photosensitive layer.
The mechanical strength was determined by determining the mechanical strength.

Note 3) Electrostatic properties: In a dark room at a temperature of 20°C and 165% RH, each photosensitive material was subjected to corona discharge for 20 seconds at -6 and ■ using a paper analyzer (Paper Analyzer 5P-428 model manufactured by Kawaguchi Denki ■). After that, leave it for 10 seconds, and the surface potential at this time is
1° was measured. Next, the potential ■7° was measured after being left standing in the dark for 60 seconds, and the retention of the potential after dark decay for 60 seconds, that is, the dark decay retention rate (DRR (%)) was determined (
V? . /V+o)X100 (%).

After the surface of the photoconductive layer is charged to -400 V by corona discharge, the surface of the photoconductive layer is irradiated with visible light at an illuminance of 2.0 lux, and the time required for the surface potential (V+) to attenuate to 1/10. From this, the exposure amount E171° (looks
seconds).

Note 4) Image quality: After leaving each photosensitive material for one day and night under the following environmental conditions, fully automatic plate making machine ELP-404V (manufactured by Fuji Photo Film) was used.
The copied image (fogging, image quality) obtained by plate making was visually evaluated.

Environmental conditions during imaging were 20°C, 65% RH and 30°C, 80°C.
%RH.

Note 5) Contact angle with water: After passing each photosensitive material once through an etching processor using a desensitizing liquid ELP-E (manufactured by Fuji Photo Film) to make the photoconductive layer surface non-greasy, A droplet of 2 μl of distilled water is placed on this, and the contact angle with the water formed is measured using a goniometer.

Note 6) Background stains on printed matter: Each photosensitive material is plate-made using fully automatic plate-making 4aELP404V (manufactured by Fuji Photo Film ■), a toner image is formed, and this is desensitized under the same conditions as above (Note 3). As an offset master, 500 sheets were printed on high-quality paper using Offset Printing i (Hamaduster 800SX model manufactured by Hamadastar ■), and background smear on all printed matter was visually determined. This is referred to as background smear I on printed matter.

For background stains on printed matter, dilute the desensitizing treatment liquid 5 times.
In addition, the test was carried out in the same manner as the above-mentioned scumming (2), except that the dampening water used during printing was diluted twice.

Case (2) corresponds to printing under stricter conditions than case (I).

Note 7) Printing durability: Process each photosensitive material under the evaluation conditions for printing stain I in property 6) above, and calculate the number of sheets that can be printed without causing background stains in non-image areas or problems with image quality in image areas of printed matter. (The greater the number of prints, the better the stiffness resistance.)

As shown in Table 1, the photosensitive material of the present invention and Comparative Example A had good smoothness and electrostatic properties of the photoconductive layer, and the actual copied images had no blurring (and the quality of the copied images was also clear). It is presumed that this is because the photoconductor and the binder resin were sufficiently adsorbed and coated the back surface of the particles.

For the same reason, even when used as an offset master original, the desensitization treatment with the desensitization treatment liquid has progressed sufficiently, and the contact angle with water in the non-image area is small, 15 degrees or less, making it sufficiently hydrophilic. There is. When actually printing and observing the background stains on the printed matter, no stains were observed at all. However, in the case of the comparative example, when a strength test and a printing durability test of the photoconductive layer were conducted, the film strength was insufficient (and a major problem occurred in durability).

On the other hand, in the case of the resin used in Comparative Example B, the agglomeration state progressed to such an extent that the dispersion for forming a photosensitive layer could not be prepared. Comparative Example C, in which a photosensitive material was prepared using only a polymer containing an acid component, had good electrostatic properties, but the smoothness of the photoconductive layer deteriorated, and when used as an offset master, the prints were heavily smudged, making it extremely unusable. It has become a thing. Furthermore, the imaging performance at high temperatures deteriorated. In the comparative example, sufficient performance was not obtained in both electrostatic properties and printing properties.

This is believed to indicate that either the interaction between the photoconductor and the binder is too strong or too weak to maintain satisfactory performance.

From the above, only the photosensitive material of the present invention satisfies the mechanical strength, electrostatic properties and moisture resistance of the photoconductive layer, and has sufficient printability even when used as an offset master original plate.

Examples 2 to 16 Copolymers shown in Table 2 as resin [A] were produced under the same conditions as those for resin (A]-i produced in Synthesis Example 1.

Table 2 The same procedure as in Example 1 was carried out except that each of these resins [A] Log (as solid content) and the resin [B] produced in Synthesis Example 2 -130g (as solid content) were used. A photosensitive material was produced.

Each photosensitive material obtained was evaluated in the same manner as in Example 1 for the surface smoothness of the photoconductive layer, film strength, electrostatic properties, and printing properties when used as an offset master original plate. As a result, each photosensitive material exhibited performance equivalent to or better than that of the photosensitive material of Example 1.

In other words, each of the photosensitive materials of the present invention has excellent chargeability, dark charge retention, and photosensitivity, and the actual copied images are also produced under high temperature and high humidity (
Even under severe conditions (30°C, 80% RH), clear images were obtained with no occurrence of soil sagging.

In addition, when offset printing was performed as an offset master original plate, a clear printed image with no ground blur was obtained even after printing 10,000 sheets.

Example 17 and Comparative Example E 48.5 g of ethyl methacrylate, 48.5 g of benzyl methacrylate, 3 g of methacrylic acid, and 200 g of toluene
After heating the mixed solution of g to a temperature of 105° C. under a nitrogen stream, azobisisobutyronitrile tog was added and reacted for 8 hours.

The weight average molecular weight of the obtained copolymer was 6,500, and the glass transition point was 40°C.

20 g of the obtained copolymer (as solid content), Example 1
-120g of resin [B] manufactured by, 200g of zinc oxide,
Heptamethine cyanine dye represented by the following structural formula 0.0
2g, phthalic anhydride 0゜15g and toluene 300g
A photosensitive layer-forming product was prepared by dispersing the mixture in a ball mill for 2 hours.

The following operations were performed in the same manner as in Example 1 to produce an electrophotographic light-sensitive material.

(Cyanine dye) Comparative photosensitive material E 48.5 g of ethyl methacrylate, 48.5 g of benzyl methacrylate, 3 g of methacrylic acid, and 200 g of toluene
After heating the mixed solution of g to a temperature of 70''C under a nitrogen stream, 7Lz1.Qg of azobisisobutyronitrile was added, and 8
Allowed time to react.

The weight average molecular weight of the obtained copolymer was 36. .

00, the glass transition point was 54°C. Comparative photosensitive material E was obtained in the same manner as in Example 17, except that 40 g (solid content) of only the copolymer as the binder resin was used.

The electrostatic properties of these photosensitive materials were measured using a paper analyzer in the same manner as in Example 1. However, a gallium-aluminum-arsenic semiconductor laser (oscillation wavelength: 830 nm) was used as the light source. The results are shown in Table-3.

Table 3 Comparative Example E had poor smoothness and dark charge retention (D,
R, R) decreased significantly (the apparent small E1/1° and high photosensitivity are due to the large R2H). Compared to the above Comparative Example C,
D. RoR has further deteriorated. This indicates that conventionally known resins have the problem of being extremely susceptible to the effects of the type of spectral sensitizing dye used in combination. On the other hand, the binder resin of the present invention provides a photosensitive material that is excellent in chargeability, dark charge retention, and photosensitivity even if the chemical structure of the spectral sensitizing dye is greatly changed.

Examples 18-30 As resin [B], the copolymers shown in Table 4 were produced under the same conditions as shown in Synthesis Example 2.

Table 4 Resin CA) and Resin CB] were combined as shown in Table 5, using 320 g of resin A and 20 g of resin [B] (each as a solid content), and the other procedures were the same as in Example 17 to prepare each photosensitive material. The electrostatic properties of each photosensitive material were measured in the same manner as in Example 17, and the results are shown in Table 5.

(Effects of the Invention) According to the present invention, an electrophotographic photosensitive material having excellent performance in terms of smoothness and strength of a photoconductive layer, electrostatic properties, imaging performance, as well as background smearing and rigidity resistance of printed matter can be obtained. can get.

Further, the electrophotographic light-sensitive material of the present invention can have excellent photoconductive layer smoothness, electrostatic properties, etc. even when used in combination with various aggravating dyes.

Claims (1)

[Scope of Claims] An electrophotographic photoreceptor having a photoconductive layer containing at least an inorganic photoconductive material and a binder, wherein the binder resin contains at least two of the following resins [A] and resin [B]. An electrophotographic photoreceptor comprising: (i) Resin [A] has a weight average molecular weight of 10^3 to 10^4, and -P
A resin containing 0.05 to 20% by weight of a copolymer component containing at least one acidic group selected from O_3H group, -COOH group, and -SO_3H group. (ii) Resin [B] A copolymer component having a weight average molecular weight of 10^4 to 3 x 10^5 and containing an OH group and/or a basic group.
Resin containing 05-15% by weight.