JPH07109513B2 - Electrophotographic photoreceptor - Google Patents

Description

TECHNICAL FIELD 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) The electrophotographic photosensitive member has various configurations in order to obtain predetermined characteristics or depending on the type of electrophotographic process to be applied.

Typical electrophotographic photoconductors are a photoconductor having a photoconductive layer formed on a support and a photoconductor having an insulating layer on the surface thereof, which are widely used. A photoreceptor comprising a support and at least one photoconductive layer is used for image formation by the most general electrophotographic process, that is, charging, image exposure and development, and optionally transfer.

Further, a method of using an electrophotographic photosensitive member as an offset original plate for direct plate making is widely used.

The binder used for forming the photoconductive layer of the electrophotographic photosensitive member is excellent in film-forming property of itself and the ability to disperse the photoconductive powder in the binder, and the formed recording layer. Adhesiveness to the substrate is good, and the photoconductive layer of the recording layer is excellent in charging ability, small dark decay, large light decay, little pre-exposure fatigue, and changes in humidity during imaging. It is necessary to have various electrostatic characteristics such as being required to stably hold these characteristics and excellent image pickup properties.

Resins that have been known for a long time include, for example, silicone resin (Japanese Patent Publication No. 34-6670) and styrene-butadiene resin (Japanese Patent Publication No.
5-1960), alkyd resin, maleic acid resin, polyamide (Japanese Patent Publication No. 35-11219), vinyl acetate resin (Japanese Patent Publication No.
41-2425), vinyl acetate copolymer (Japanese Patent Publication No. 41-2426)
No.), acrylic resin (Japanese Patent Publication No. 35-11216), and acrylic acid ester copolymer (for example, Japanese Patent Publication No. 35-11219, Japanese Patent Publication No. 36).
-8510, Japanese Patent Publication No. 41-13946, etc.) are known.

However, in the electrophotographic photosensitive materials using these resins, 1) the affinity for the photoconductive powder is insufficient and the dispersibility of the coating liquid becomes poor, and 2) the chargeability of the photoconductive layer is poor. Low,
3) Poor quality of image part (especially halftone dot reproducibility / resolution) of copied image 4) Image quality is easily affected by environment (eg, high temperature / high humidity, low temperature / low humidity) at the time of making copied image 5) Photosensitive layer The film strength and adhesiveness of No. 2 are not sufficient, and particularly when used as an offset master, there is a problem that the number of printed sheets cannot be increased due to detachment of the photosensitive layer during offset printing.

Various methods have been proposed as a method for improving the electrostatic properties of the photoconductive layer, and one method thereof is, for example, a compound containing a carboxyl group or a nitro group in an aromatic ring or a furan ring, or an anhydride of dicarboxylic acid. Further combining,
The method of coexisting in the photoconductive layer is Japanese Examined Patent Publication No. 42-6878 and Japanese Examined Patent Publication No. 4
No. 5-3073. However, even the light-sensitive materials improved by these methods have insufficient electrostatic characteristics, and no particularly excellent light attenuation characteristics have been obtained. Therefore, a method of adding a large amount of a sensitizing dye to the photoconductive layer has been conventionally used to improve the lack of sensitivity of the light-sensitive material. However, the light-sensitive material produced by such a method has a significantly deteriorated whiteness. However, there is a problem in that the quality of the recording material deteriorates, and in some cases, the dark attenuation of the photosensitive material deteriorates, so that a sufficient copied image cannot be obtained.

On the other hand, JP-A-60-10254 discloses a method of adjusting the average molecular weight of the resin as the binder resin used for the photoconductive layer. That is, when an acrylic resin having an acid value of 4 to 50 and a component having an average molecular weight distribution of 10 ³ to 10 ⁴ and a component having a distribution of 10 ⁴ to 2 × 10 ⁵ are used in combination, electrostatic properties (particularly, PPC
A technique for improving the reproducibility as a photoconductor) and the moisture resistance is described.

Further, research on a lithographic printing plate precursor using an electrophotographic photosensitive member has been earnestly conducted, and a binder resin for a photoconductive layer which has both electrostatic properties as an electrophotographic photosensitive member and printing properties as a printing plate precursor. As, for example, in Japanese Examined Patent Publication (Kokoku) No. 50-31011, in the presence of fumaric acid (meth) copolymerized with other monomers and monomers, Mw1.8 ~ 10 × 10 ⁴ Tg 10 ~ 80 ℃ resin, A combination of a (meth) acrylate-based monomer and a copolymer of a monomer other than fumaric acid, and in JP-A-53-54027, the carboxylic acid group is separated from the ester bond by at least 7 atoms. Those using a terpolymer containing a (meth) acrylic acid ester having a substituent having a substituent, and in JP-A-54-20735 and JP-A-57-202544, acrylic acid and hydroxyethyl (meth) acrylate are used. Using a quaternary or quaternary copolymer containing In JP-A-58-68046, a terpolymer containing a (meth) acrylic acid ester having an alkyl group having 6 to 12 carbon atoms as a substituent and a carboxylic acid-containing vinyl monomer is used. Is effective in improving the desensitizing property of the photoconductive layer.

(Problems to be solved by the invention) However, even if the above-mentioned resin is considered to have an effect on electrostatic characteristics, moisture resistance characteristics, and durability, it is particularly evaluated in terms of actual chargeability and dark charge retention. However, there were problems with the electrostatic properties, such as photosensitivity and photosensitivity, and the smoothness of the photoconductive layer, which was not practically satisfactory.

Further, the binder resin that was developed as an electrophotographic lithographic printing original plate also had problems with the above-mentioned electrostatic properties and the background stain of the printed matter when actually evaluated.

The present invention improves the above-mentioned problems of the conventional electrophotographic photosensitive member.

An object of the present invention is to provide an electrophotographic photoreceptor of high image quality which has improved electrostatic characteristics (especially dark charge retention and photosensitivity) and reproduces a copy image faithful to the original image.

Another object of the present invention is to provide an electrophotographic photosensitive member having a clear and high-quality image even when the environment during copy image formation changes such as low temperature and low humidity or high temperature and high humidity.

Another object of the present invention is to provide an electrophotographic photosensitive member that is not easily affected by the type of sensitizing dye that can be used in combination.

Another object of the present invention is as an electrophotographic lithographic printing plate precursor,
A lithographic plate that has excellent electrostatic characteristics (especially dark charge retention and photosensitivity), reproduces a copy image that is faithful to the original image, and does not cause spot stains as well as uniform stains on the entire surface of the printed matter. It is to provide an original printing plate.

(Means for Solving Problems) The above problems are caused in an electrophotographic photoreceptor having a photoconductive layer containing at least an inorganic photoconductive material and a binder resin,
It has been found that the binder resin can be solved by an electrophotographic photosensitive member characterized by containing at least two kinds of the following resin [A] and resin [B].

(I) Resin [A] having a weight average molecular weight of 10 ^{3 to} 3 × 10 ⁴ and -PO ₃ H
₂ group, -COOH group and -SO ₃ at least one acidic group to the polymer main chain terminal only bound to become resin is selected from H groups.

(Ii) Resin [B] A resin having a weight average molecular weight of 10 ^{4 to} 5 × 10 ⁵ and not containing the above acidic group, basic group and OH group.

The binder resin used in the present invention contains at least one of the above acidic groups.
The low molecular weight resin [A] which does not contain the seed in the side chain linked to the polymer main chain but bonds only to the end of the main chain and the high molecular weight resin which does not contain the acidic group, the basic group and the OH group at all. It is composed of at least a molecular weight resin [B].

The amount of the acidic group present in the polymer is the same as that in the resin [A].
The amount is 0.05 to 20% by weight, and more preferably 0.5 to 10% by weight. The weight average molecular weight of the resin [A] is 10 ^{3 to} 3 × 10 ⁴
However, it is more preferably 5 × 10 ^{3 to} 1.5 × 10 ⁴ .

The glass transition point of the resin [A] is preferably −10 ° C. to 100 ° C.
Range, more preferably -5 ° C to 80 ° C.

The resin [B] is a resin having a weight average molecular weight of 10 ^{4 to} 5 × 10 ^{5 and} containing no acidic group, basic group or OH group. The weight average molecular weight is more preferably 2 × 10 ^{4 to} 3 × 10 ⁵ .

The glass transition point of the resin [B] is preferably in the range of 0 ° C to 120 ° C, more preferably 10 ° C to 80 ° C.

The conventionally known binder resin containing an acidic group as described above is mainly used for offset masters and has a large molecular weight in order to improve printing durability by maintaining the film strength (for example, 5
× 10 ⁴ or more), and these copolymers were random copolymers, and the acidic group-containing copolymer component was randomly present in the polymer main chain.

On the other hand, the resin [A] used in the present invention is a polymer in which the acidic group contained in the resin is bonded only to the terminal of the main chain.

In the present invention, since the acidic group bonded to the polymer terminal of the resin [A] is adsorbed to the stoichiometric defect of the inorganic photoconductor and is a low molecular weight substance, the surface coating of the photoconductor is covered. By improving the property, the trap of the photoconductor is compensated and the humidity characteristic is improved, while the photoconductor is sufficiently dispersed and aggregation is suppressed. The resin [B] is sufficient to make the mechanical strength of the photoconductive layer insufficient with the resin [A] alone.

When the content of the acidic group in the resin [A] is less than 0.05% by weight, the initial potential is low and a sufficient image density cannot be obtained. On the other hand, when the content of the acidic group is more than 20% by weight, the dispersibility decreases, the high humidity property of the film smoothness and the electrophotographic property decreases, and the scumming increases when used as an offset master. Not preferable.

When a photoconductor with a rough surface of the photoconductive layer is used as the electrophotographic lithographic printing original plate, the zinc oxide particles as the photoconductor and the binder resin are not dispersed in an appropriate state and light is generated in the presence of aggregates. Since the conductive layer is formed, even if desensitizing treatment is performed with a desensitizing treatment liquid, the non-image area is not sufficiently hydrophilicized uniformly, causing the adhesion of printing ink during printing,
As a result, scumming occurs in the non-image portion of the printed matter.

Further, 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 be sufficiently adsorbed and the particle surface can be covered, so that the photoconductive layer can be smoothed. Although it is possible to obtain an image quality which is good in the property and electrostatic property and is free from background stain, the film strength is still insufficient, and satisfactory results cannot be obtained in the durability.

Only when the resin of the present invention is used, the interaction between adsorption and coating of the inorganic photoconductor and the binder resin is appropriately performed, and the film strength of the photoconductive layer is maintained.

The resin [A] may be any conventionally known resin as long as it has the above-mentioned physical properties, and examples thereof include polyester resin, modified epoxy resin, silicone resin, olefin resin, polycarbonate resin, vinyl alkanoate resin, and allyl alkanoate. Resin, modified polyamide resin, phenol resin,
A fatty acid-modified alkyd resin, acrylic resin or the like is used.

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

General formula (I) In the general formula (I), X represents a hydrogen atom, a halogen atom (for example, a chloro atom or a bromo atom), a cyano group or an alkyl group having 1 to 4 carbon atoms. R'is 1 to 18 carbon atoms
An optionally substituted alkyl group (for example, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, octyl group, decyl group, dodecyl group, tridecyl group, tetradecyl group, 2-methoxyethyl group) , 2-
Ethoxyethyl group), optionally substituted alkenyl group having 2 to 18 carbon atoms (for example, vinyl group, allyl group, isopropenyl group, butenyl group, hexenyl group, heptenyl group, octenyl group, etc.), carbon number 7 To 12 optionally substituted aralkyl groups (eg, benzyl group, phenethyl group, methoxybenzyl group, ethoxybenzyl group, methylbenzyl group, etc.), and optionally substituted cycloalkyl groups having 5 to 8 carbon atoms (eg, Cyclopentyl group, cyclohexyl group, cycloheptyl group, etc.), aryl group (for example, phenyl group, tolyl group, xyl group, mesityl group, naphthyl group, methoxyphenyl group, ethoxyphenyl group,
Chlorophenyl group, dichlorophenyl group, etc.).

Further, the resin [A] of the present invention may contain, in addition to the above-mentioned monomer of the general formula (I), another monomer as a copolymerization component.

For example, α-olefins, vinyl alkanoates or allyl esters, acrylonitrile, methacrylonitrile, vinyl ethers, acrylamides, methacrylamides, styrenes, heterocyclic vinyls (for example, vinylpyrrolidone, vinylpyridine, vinylimidazole,
Vinyl thiophene, vinyl imidazoline, vinyl pyrazole, vinyl-dioxane, vinyl kirin, vinyl thiazole, vinyl oxazine, etc.) and the like. Particularly, vinyl acetate, allyl acetate, acrylonitrile, methacrylonitrile, styrenes and the like are preferable components from the viewpoint of improving the film strength.

The resin [A] may be synthesized so that the acidic group is bonded to the terminal of the main chain of the copolymer composed of these copolymerization components. Specifically, a method using a polymerization initiator containing the acidic group or a functional group that can be converted later to replace the acidic group, or a chain containing the acidic group or a functional group that can be converted into the acidic group later. It can be produced by a method using a transfer agent, a method using both of them in combination, and a method of introducing the functional group by utilizing a termination reaction in the anionic polymerization method.

For example, P.Dreyfuss, RPQuirk, Encycl.Polym.Sci.Eng.
7 , 551 (1987), V.Percec, Appl.Polym.Sci. 285 , 95 (198
5), PFRempp, E.Franta, Adv.Polym.Sci. 58 , 1 (198
4), Y.Yamashita, J.Appl.Polym.Sci, Appl.Polym.Symp.
36 , 193 (1981), R. Asami, M. Takaki, Makromol. Chem, Sup
It can be produced by the synthetic method described in the review article such as pl. 12 , 163 (1985).

The resin [B] of the present invention is a resin having a weight average molecular weight of 10 ^{4 to} 5 × 10 ⁵ which does not contain the above-mentioned acidic group in neither the polymer main chain nor the terminal, nor does it contain a basic group or an OH group. .
It is preferable that the glass transition point of the resin [B] is 0 ° C to 120 ° C. Any of the resins conventionally used as a binder resin for electrophotography may be used, and they may be used alone or in combination. For example, the materials cited in the review articles such as Harumiya Miyahara, Hidehiko Takei Imaging 1978 No.8 9-12, Ryuji Kurita, Jiro Ishiwatari, Kogaku, 17, 278-284 (1968) can be mentioned.

Specifically, olefin polymers and copolymers, vinyl chloride copolymers, vinylidene chloride copolymers, vinyl alkanoate polymers and copolymers, allyl alkanoate polymers and copolymers, styrene and its derivatives, Polymers and copolymers, butadiene-styrene copolymer, isoprene-styrene copolymer, butadiene-unsaturated carboxylic acid ester copolymer, acrylonitrile copolymer, methacrylonitrile copolymer, alkyl vinyl ether copolymer, Acrylic ester polymers and copolymers, methacrylic acid ester polymers and copolymers, styrene-acrylic acid ester copolymers, styrene-methacrylic acid ester copolymers, itaconic acid diester polymers and copolymers, maleic anhydride Acid copolymer, acrylamide copolymer, methacrylamide copolymer, water Group modified silicone resins, polycarbonate resins, ketone resins, amide resins, hydroxy- and carboxy-modified polyester resins, butyral resins,
Polyvinyl acetal resin, cyclized rubber-methacrylic acid ester copolymer, cyclized rubber-acrylic acid ester copolymer, copolymer containing a nitrogen atom-free heterocycle (for example, furan ring, tetrahydrofuran Ring, thiophene ring, dioxane ring, dioxolane ring, lactone ring, benzofuran ring, benzothiophene ring, 1,3
-Dioxetane ring etc.) Epoxy resin and the like.

More specifically, (meta) represented by the general formula (I)
Examples thereof include a methacrylic copolymer or a polymer containing an acrylic ester monomer as a copolymer component and the total amount of the acrylic ester monomer being 30% by weight or more. Specific preferred examples of the general formula (I) include the same as those described above.

Further, the component copolymerizable with the (meth) acrylic acid ester may be a monomer other than the general formula (I), and examples thereof include α-olefins, vinyl alkanoate or allyl esters, and acrylonitrile. , Methacrylonitrile, vinyl ethers, acrylamides, methacrylamides, styrenes, heterocyclic vinyls [for example, non-metal atoms other than nitrogen atom (oxygen atom, sulfur atom, etc.) 1
A heterocyclic ring containing 5 to 7 members, and specific compounds include vinylthiophene, vinyl-dioxane, vinyl-furan and the like]. Preferred examples include, for example, vinyl alkanoate or allyl esters having 1 to 3 carbon atoms in the alkyl moiety, acrylonitrile,
Methacrylonitrile, styrene, and styrene derivatives (for example, vinyltoluene, butalstyrene, methoxystyrene, chlorostyrene, dichlorostyrene, bromostyrene, ethoxystyrene, etc.) and the like can be mentioned.

On the other hand, examples of the basic group not contained in the resin [B] of the present invention include an amino group which may have a substituent and a nitrogen atom-containing heterocyclic group.

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

The ratio of the weight average molecular weight of resin [A] and resin [B] is 1.
2 or more is preferable. It is more preferably 2.0 or more.

As the inorganic photoconductive material used in the present invention, zinc oxide,
Examples thereof include titanium oxide, zinc sulfide, cadmium sulfide, cadmium carbonate, zinc selenide, cadmium selenide, tellurium selenide and lead sulfide.

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

In the present invention, various dyes can be used together as a spectral sensitizer, if necessary. For example, Harumi Miyamoto, Hidehiko Takei, Imaging 1973 (No.8) page 12, CJ Young et al., RCA
Review 15 , 469 (1954), Kyohei Kiyota, The Institute of Electrical Communication, J 63-C (No. 2), 97 (1980), Yuji Harasaki, etc., Journal of Industrial Chemistry 66 78 and 188 (1963), Tadaaki Tani, Carbonaceous dyes, diphenylmethane dyes, triphenylmethane dyes, which are cited as reviews in the Journal of the Photographic Society of Japan 35 , 208 (1972), etc.
Examples thereof include xanthene dyes, phthalein dyes, polymethine dyes (eg, oxonol dyes, merocyanine dyes, cyanine dyes, rhodacyanine dyes, styryl dyes, etc.), phthalocyanine dyes (which may contain a metal), and the like.

More specifically, those mainly containing carbonium dyes, triphenylmethane dyes, xanthene dyes, and phthalein dyes are disclosed in JP-B-51-452 and JP-A-50-903.
34, JP-A-50-114227, JP-A-53-39130, JP-A-5
3-82353, U.S. Pat.No. 3,052,540, U.S. Pat.No. 4,054,
And those described in JP-A-57-16456.

Oxonol dye, merocyanine dye, cyanine dye,
As a polymethine dye such as rhodacyanine dye, FMHa
Dyes described in mer `` The Cyanine Dyes and Related Compounds '' and the like can be used, and more specifically, U.S. Pat.No. 3,047,384, U.S. Pat.No. 3,110,591, U.S. Pat. , U.S. Patent No. 3,
128,179, U.S. Pat.No. 3,132,942, U.S. Pat.No. 3,622,
317, British Patent 1,226,892, British Patent 1,309,274
No., British Patent No. 1,405,898, Japanese Patent Publication No. 48-7814, Japanese Patent Publication No.
Examples include dyes described in No. 55-18892.

Furthermore, as a polymethine dye for spectrally sensitizing the near infrared to infrared light region having a long wavelength of 700 nm or more, JP-A-47-840 and JP-A-
47-44180, JP-B-51-41061, JP-A-49-5034, JP-A-49-45122, JP-A-57-46245, JP-A-56-35141
JP-A-57-157254, JP-A-61-26044, JP-A-61-
27551, U.S. Pat.No. 3,619,154, U.S. Pat.No. 4,175,95
No. 6, "Research Disclosure", 1982, 216, Nos. 117-11
Examples include those described on page 8. The photoconductor of the present invention is excellent in that the performance thereof hardly changes depending on the sensitizing dye even when various sensitizing dyes are used in combination.

Furthermore, if necessary, various conventionally known additives for electrophotographic photosensitive layers such as chemical sensitizers can be used in combination. For example, the aforementioned review article: Imaging 1973 (No.8)
Electron-accepting compounds (eg halogen, benzoquinone, chloranil, acid anhydrides, organic carboxylic acids, etc.) in the review article on page 12, etc., Hiroshi Komon et al., “Recent Developments and Commercialization of Photoconductive Materials and Photoconductors” [Chapter 4 to Chapter 6: Polyarylalkane compounds, hindered phenol compounds, p-phenylenediamine compounds and the like, which are the reference examples of the Japanese Scientific Information Co., Ltd. Publishing Department (1986)].

The addition amount of these various additives is not particularly limited,
Usually 0.0001 to 2.0 parts by weight with respect to 100 parts by weight of the photoconductor.

The thickness of the photoconductive layer is preferably 1 to 100 μ, particularly 10 to 50 μ.

When the photoconductive layer is used as the charge generation layer of the laminated type photoreceptor having the charge generation layer and the charge transport layer, the thickness of the charge generation layer is preferably 0.01 to 1 μm, particularly preferably 0.05 to 0.5 μm.

In some cases, an insulating layer is additionally provided for the purpose of protecting the photoreceptor and improving durability and dark decay characteristics. At this time, the insulating layer is set to be relatively thin, and the insulating layer provided when the photoconductor is used in a specific electrophotographic process is set to be relatively thick.

In the latter case, the thickness of the insulating layer is 5 to 70μ, especially 10 to
It is set to 50μ.

Examples of the charge transport material for the laminated photoreceptor include polyvinyl carbazole, oxazole dyes, pyrazoline dyes, triphenylmethane dyes, and the like. The thickness of the charge transport layer is preferably 5 to 40 μ, particularly 10 to 30 μ.

Typical resins used for forming the insulating layer or the charge transport layer are polystyrene resin, polyester resin, cellulose resin, polyether resin, vinyl chloride resin, vinyl acetate resin, vinyl chloride-vinyl chloride 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 appropriately used.

The photoconductive layer according to the present invention can be provided on a conventionally known support. Generally speaking, the support of the electrophotographic photosensitive layer is preferably conductive, and as the conductive support, for example, a substrate such as metal, paper or plastic sheet is impregnated with a low resistance substance as in the conventional case. Those which have been subjected to a conductive treatment, such as those which have been subjected to a conductivity treatment, those which are provided with conductivity on the back surface of the substrate (the surface opposite to the surface on which the photosensitive layer is provided), and have at least one layer coated for the purpose of preventing curling, Water-resistant adhesive layer provided on the surface of the body, at least one precoat layer provided on the surface layer of the support, if necessary, laminate of electroconductive plastic substrate onto which Al or the like is vapor-deposited on paper It can be used.

Specifically, as an example of a conductive substrate or a conductive material,
Yukio Sakamoto, Electrophotography, 14, (No.1), p2 ~ 11 (1975), Hiroyuki Moriga, "Chemistry of Introductory Special Papers" Polymer Publishing (1975),
MF Hoover, J. Macromol. Sci. Chem. A-4 (6), No. 1327-
Use those described on page 1417 (1970).

(Example) Hereinafter, the present invention will be illustrated by examples, but the content of the present invention is not limited thereto.

Example 1 and Comparative Examples AF (Synthesis Example 1) A mixed solution of 95 g of ethyl acrylate and 200 g of toluene was heated to a temperature of 90 ° C under a nitrogen stream, and then 4,4'-azobis (4-cyanovaleric acid) was added. 5 g (abbreviated as ABCV below) was added and reacted for 10 hours.

The obtained copolymer (I) had a weight average molecular weight of 8,300 and a glass transition point of 46 ° C.

(Synthesis example 2) 95 g of ethyl methacrylate, 5 g of acrylic acid and 2 toluene
After heating 00 g of the mixed solution to a temperature of 90 ° C. under a nitrogen stream,
6 g of 2,2'-azobis (2,4-dimethylvaleronitrile) was added and reacted for 10 hours. The obtained copolymer (II) had a weight average molecular weight of 7,800 and a glass transition point of 45 ° C.

(Synthesis Example 3) A mixed solution of 100 g of ethyl methacrylate and 200 g of toluene was heated to a temperature of 80 ° C. under a nitrogen stream, and then 1 g of 2,2′-azobis (1-cyclohexanecarbonitrile) was added,
Reacted for hours. The weight average molecular weight of the obtained copolymer (III) was 140,000 and the glass transition point thereof was 48 ° C.

(Synthesis Example 4) A mixed solution of 100 g of ethyl methacrylate and 200 g of toluene was heated to a temperature of 70 ° C under a nitrogen stream, 2 g of 2,2'-azobis (4-cyanoheptanol) was added, and the mixture was reacted for 8 hours. The resulting copolymer mixture, glutaric anhydride 0.92
g and 1 g of pyridine were added, and the mixture was further reacted at a temperature of 80 ° C. for 10 hours. The weight average molecular weight of the obtained copolymer (IV) was 10
The glass transition point was 5000 and the glass transition point was 47 ° C.

Example 1 20 g (as solid content) of the copolymer (I) produced in Synthesis Example 1, poly (ethyl methacrylate) (weight average molecular weight)
140,000) 20 g, zinc oxide 200 g, tetrabromophenol blue 0.07 g, phthalic anhydride 0.20 g and toluene 300 g are dispersed in a ball mill for 2 hours to prepare a photosensitive layer-forming material, which is then applied to a conductive-treated paper. It was applied with a wire bar so that the dry adhesion amount was 25 g / m ² and dried at 110 ° C. for 1 minute. Next, an electrophotographic photosensitive member was prepared by leaving it in the dark at 20 ° C. and 65% RH for 24 hours.

Comparative Example A Comparative electrophotographic image was obtained in the same manner as in Example 1 except that 40 g (as solid content) of the copolymer (I) produced in Synthesis Example 1 was used instead of the binder resin used in Example 1. Photoconductor A
Was manufactured.

Comparative Example B A comparative electrophotographic photosensitive material was prepared in the same manner as in Example 1 except that 40 g (as solid content) of the copolymer (II) produced in Synthesis Example 2 was used instead of the binder resin used in Example 1. Body B was manufactured.

Comparative Example C Instead of the binder resin used in Example 1, 20 g (as solid content) of the copolymer (II) produced in Synthesis Example 2 and poly (ethyl methacrylate) (weight average molecular weight 140,000) 2
A comparative electrophotographic photosensitive member C was produced in the same manner as in Example 1 except that 0 g was used.

Comparative Example D Instead of the binder resin used in Example 1, 20 g (as solid content) of the copolymer (II) produced in Synthesis Example 2 and poly [ethyl methacrylate / acrylic acid (98 / 2.0) weight ratio] A comparative electrophotographic photoreceptor D was produced in the same manner as in Example 1 except that 20 g (weight average molecular weight 74,000) was used.

Comparative Example E In the same manner as in Example 1 except that 40 g of poly [ethyl methacrylate / acrylic acid (98 / 2.0)] (weight average molecular weight 74,000) was used instead of the binder resin used in Example 1, A comparative electrophotographic photoreceptor E was manufactured.

Comparative Example F Instead of the binder resin used in Example 1, 20 g (as solid content) of the copolymer (I) produced in Synthesis Example (1) and the copolymer (IV produced in Synthesis Example (4) (IV) ) A comparative electrophotographic photoreceptor F was produced in the same manner as in Example 1 except that 20 g (as solid content) was used.

The film properties (surface smoothness) of these photosensitive materials, the electrostatic characteristics, the imaging properties, and the imaging properties under the environmental conditions of 30 ° C. and 80% RH were examined. Further, the desensitizing property of the photoconductive layer when these photosensitive materials are used as a master plate for an offset master (expressed by the contact angle with water of the photoconductive layer after the desensitizing treatment)
The printability (background stain, printing durability, etc.) was examined. The image pick-up and printability were obtained by exposing and developing the fully automatic plate-making ELP404V (manufactured by Fuji Photo Film Co., Ltd.) using the developer ELP-T to form an image, and using the desensitizing liquid ELP-E. It was examined using a lithographic printing plate obtained by etching with an etching processor (the Hamada Star 800SX type manufactured by Hamada Star Co., Ltd. was used as the printing machine).

The above results are summarized in Table-1.

Embodiments of the evaluation items shown in Table 1 are as follows.

Note 1) Smoothness of photoconductive layer: The photosensitive material obtained was measured for smoothness (sec / cc) under a condition of an air capacity of 1 cc using a Beck smoothness tester (manufactured by Kumagai Riko Co., Ltd.). It was measured.

Note 2) Electrostatic characteristics: Paper analyzer (Paper Analyzer SP manufactured by Kawaguchi Electric Co., Ltd.) on each light-sensitive material in a dark room at a temperature of 20 ° C and 65% RH.
-428) for 6 seconds at 6kV corona discharge, then 10
It was left for a second, and the surface potential V ₁₀ at this time was measured. Then, the potential V ₇₀ after standing still in the dark for 60 seconds is measured,
The potential retention after dark decay for 60 seconds, that is, the dark decay retention [DRR (%)] was calculated by (V ₇₀ / V ₁₀ ) × 100 (%). Also, 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 having an illuminance of 2.0 lux, and the time until the surface unit (V ₁₀ ) is attenuated to 1/10 Then, the exposure amount E _1/10 (lux · second) is calculated from this.

Note 3) Imaging: Each photosensitized material was allowed to stand for one day under the following environmental conditions, and then a copy image (fog, image) obtained by plate-making with a fully automatic plate-making machine ELP-404V (manufactured by Fuji Photo Film Co., Ltd.) Image quality) was visually evaluated. Environmental conditions at the time of imaging are 20 ° C 65% RH (I) and 30 ° C
Conducted at 80% RH (II).

Note 4) Contact angle with water: Each light-sensitive material was passed through an etching processor once using a desensitizing solution ELP-E (manufactured by Fuji Photo Film Co., Ltd.) to desensitize the photoconductive layer surface. After that, a drop of distilled water (2 μl) is put on this, and the contact angle with the formed water is measured with a goniometer.

Note 5) Background stain of printed matter: Each photosensitive material is made into a toner image by making a plate with a fully automatic plate-making machine ELP-404V (manufactured by Fuji Photo Film Co., Ltd.) and desensitized under the same conditions as above (Note 3). After processing, this is applied to an offset printing machine (Hamada Star 800SX type manufactured by Hamada Star Co., Ltd.) as an offset master to print 500 sheets on high-quality paper, and the background stain of all prints is visually determined. This is designated as background stain I of the printed matter.

For the background stain II of the printed matter, the desensitizing solution is diluted 5 times,
In addition, the test is performed in the same manner as the background stain I, except that the dampening water at the time of printing is diluted twice. The case of II corresponds to printing under a stricter condition than I.

Note 6) Printing durability: Indicates the number of sheets that can be printed without causing problems with background stains in the non-image area of printed matter and image quality in the image area by processing each photosensitive material under the evaluation conditions for print stain I in Note 5) above. (The larger the number of printed sheets, the better the printing durability.) As shown in Table 1, the photosensitive material of the present invention has good smoothness and electrostatic characteristics of the photoconductive layer, and is not suitable for actual copying. The image had no background fog and the copy quality was clear.

This means that the photoconductor and the binder resin are sufficiently absorbed, and
It is presumed that this is because the interaction between the binders was sufficiently maintained at the same time as coating the surface of the particles.
For the same reason, even when used as an offset master original plate, the desensitizing treatment with the desensitizing treatment liquid proceeds sufficiently, the contact angle with water of the non-image area is as small as 15 degrees or less, and it is sufficiently hydrophilicized. You can see that When actually printed and observed the background stain of the printed matter, the background stain was not recognized at all, and it was found that the number of printable sheets exceeded 10,000. Comparative examples A and B are
The number of printable sheets was lower than that of the light-sensitive material of the present invention. In Comparative Example C, the number of printable sheets is high, but the DR
R. deteriorated compared to the material of the present invention.

Comparative Examples DF have electrophotographic characteristics (especially DRR and E _1/10 ).
Was deteriorated, and the offset master original plate was liable to cause scumming, and even when printed, it was about 3000 sheets at most.

From the above, an electrophotographic photosensitive member satisfying electrostatic characteristics and printability can be obtained only when the resin of the present invention is used.

Example 2 A mixed solution of 95 g of ethyl methacrylate, 5 g of thioglycolic acid, and 200 g of toluene was heated to a temperature of 75 ° C. under a nitrogen stream, and then 1.0 g of azobisisobutyronitrile was added and reacted for 8 hours. The weight average molecular weight of the obtained copolymer (V) was 7,800, and the glass transition point was 46 ° C.

Instead of the resin used in Example 1, 15 g of copolymer (V)
(As solid content), poly (butyl methacrylate)
A photoconductor was produced in the same manner as in Example 1 except that 25 g of [weight average molecular weight 180,000] was used, and each property was measured in the same manner as in Example 1. The photoconductive layer surface of the photoconductor has a smoothness of 80.
It was smooth at (sec / cc). V _10; -560V, DRR; 93
%, E _1/10 3.5 (lux ・ sec), (30 ℃, 80% RH)
The image quality was excellent in the image pickup property.

The light-sensitive material of the present invention has excellent chargeability, dark charge retention rate, and photosensitivity, and the actual copied image also causes ground fog and fine line skipping even under severe conditions of high temperature and high humidity (30 ° C., 80% RH). It gave a clear image with no equality.

Furthermore, after printing in the same manner as in Example 1 and printing as an offset master original plate or printing 10,000 sheets, a printed matter of clear image quality with no background stain was obtained.

Examples 3 to 8 Each copolymer was synthesized under the same conditions as in Example 2 except that the thioglycolic acid used in Example 2 was replaced with the compound in Table-2.

Using each of these copolymers, processing was performed under the same conditions as in Example 2 to prepare each light-sensitive material.

The photoconductors of the present invention all showed excellent characteristics.

Example 9 A mixed solution of 95 g of benzylmethacrylylate and 200 g of toluene was heated to a temperature of 95 ° C. under a nitrogen stream, 5 g of 2,2′-azobis (4-cyanoheptanol) was added, and the mixture was reacted for 8 hours. . After further raising the temperature to 85 ° C, 1.2 g of succinic anhydride
And 1 g of pyridine were added and reacted for 10 hours. The weight average molecular weight of the obtained copolymer (XII) was 8,500 and the glass transition point thereof was 38 ° C.

A light-sensitive material was prepared in the same manner as in Example 2, except that 15 g of the copolymer (XII) was used instead of the copolymer [V].

Each property was measured in the same manner as in Example 1.

The light-sensitive material of the present invention has excellent chargeability, dark charge retention rate, and photosensitivity, and the actual copied image also causes ground fog and fine line skipping even under severe conditions of high temperature and high humidity (30 ° C., 80% RH). It gave a clear image with no equality. Furthermore, when printed using the offset master original plate, the image quality of the printed matter after printing 10,000 sheets was clear without background stain.

Example 10 and Comparative Example G A mixed solution of 48.5 g of ethylene methacrylate, 45.5 g of benzyl methacrylate, 4.0 g of thioglycolic acid and 200 g of toluene was heated to a temperature of 90 ° C. under a nitrogen stream and then ABC.
V1g was added and reacted for 8 hours.

The weight average molecular weight of the obtained copolymer [XIII] was 8,300 and the glass transition point thereof was 43 ° C. Thus obtained copolymer 10g (as solid content) polyethylmethacrylate (weight average molecular weight 80,000) 20g, zinc oxide 200g, heptamethine cyanine dye 0.02g represented by the following structural formula, phthalic anhydride 0.15g And a mixture of 300 g of toluene were dispersed in a ball mill for 2 hours to prepare a photosensitive layer-formed product. The following steps were carried out in the same manner as in Example 1 to prepare an electrophotographic photosensitive member (Example 10).

After heating a mixed solution of 48.5 g of ethyl methacrylate, 43.5 g of benzyl methacrylate, 5 g of methacrylic acid and 200 g of toluene to a temperature of 100 ° C. under a nitrogen stream, 6.0 g of azobisisobutyronitrile was added and reacted for 8 hours. . The weight average molecular weight of the copolymer [XIV] thus obtained was 8,0.
The glass transition point was 00 and the glass transition point was 43 ° C. This resin was used in Example 10
In place of the copolymer [XIII] in
A photoconductor H was produced in the same manner as in 10 (Comparative Example G).

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

Comparative Example G has worse DRR than Comparative Example D. This indicates that the conventionally known resin has a problem that it is significantly susceptible to the type of spectral sensitizing dye used in combination. On the other hand, the binder resin of the present invention provides a light-sensitive material which is extremely excellent in charging property, dark charge retaining property and photosensitivity even if the chemical structure of the spectral sensitizing dye is largely changed.

Examples 11 to 15 The same operation as in Example 10 except that the resin [I] produced in Synthesis Example 1 and the resins shown in Table 5 below were used in combination at a (1/1) weight ratio. Each light-sensitive material was manufactured. By the same operation as in Example 10, the smoothness, film strength and electrostatic properties of each photosensitive material were measured, and the results are also shown in Table-4.

As shown in Table 4, each of the light-sensitive materials of the present invention has good strength and electrostatic characteristics of the photoconductive layer, and the actual copied image is also under high temperature and high humidity (30 ° C 80% RH). Even the image quality was clear with no background fog.

(Effects of the Invention) According to the present invention, an electrophotographic photosensitive material having excellent properties in terms of smoothness and strength of a photoconductive layer, electrostatic characteristics, image pick-up property, as well as scumming of printed matter and printing durability. Is obtained.

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

Claims (1)

[Claims] 1. An electrophotographic photoreceptor having a photoconductive layer containing at least an inorganic photoconductive material and a binder resin, wherein the binder resin is at least one of the following resins [A] and the following resin [B]: An electrophotographic photosensitive member comprising at least one kind. (I) Resin [A] having a weight average molecular weight of 10 ^{3 to} 3 × 10 ⁴ and -PO ₃ H
₂ group, -COOH group and -SO ₃ at least one acidic group to the polymer main chain terminal only bound to become resin is selected from H groups. (Ii) Resin [B] A resin having a weight average molecular weight of 10 ^{4 to} 5 × 10 ⁵ and not containing the above acidic group, basic group and OH group.