JP2632157B2 - Electrophotographic photoreceptor - Google Patents

Description

The present invention relates to an electrophotographic photoreceptor, and more particularly, to an electrophotographic photosensitive member,
The present invention relates to an electrophotographic photosensitive member having excellent moisture resistance and durability.

(Prior Art) An electrophotographic photosensitive member has various configurations in order to obtain predetermined characteristics or according to the type of an applied electrophotographic process.

Representative electrophotographic photoreceptors include a photoreceptor having a photoconductive layer formed on a support and a photoreceptor having an insulating layer on the surface, and are widely used. A photoreceptor composed of a support and at least one photoconductive layer is used for image formation by the most common electrophotographic processes, ie, charging, image exposure and development, and, if necessary, transfer.

Further, a method using an electrophotographic photosensitive member as an offset master for direct plate making has been widely used.

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

For example, silicone resins (Japanese Patent Publication No. 34-6670), styrene-butadiene resins (Japanese Patent Publication No. 35-1960), alkyd resins, maleic acid resins, polyamides (Japanese Patent Publication No. 35-11219), Vinyl acetate resin (JP-B 41-2425), vinyl acetate copolymer (JP-B
No. 41-2426), acrylic resin (JP-B No. 35-11216),
Acrylic ester copolymer (for example, Japanese Patent Publication No. 35-11219)
Nos. JP-B-36-8510, JP-B-41-13946, etc.) are known.

However, in the electrophotographic photosensitive material using these resins, 1) the affinity with the photoconductive powder is insufficient, and the dispersibility of the coating liquid is poor. 2) The chargeability of the photoconductive layer is poor. Low,
3) Poor quality of the image portion (particularly halftone dot reproducibility / resolution) of the copied image 4) The image quality is easily affected by the environment (for example, high temperature, high humidity, low temperature, low humidity) at the time of creating the copied image 5) Photosensitive layer However, when used as an offset master, there is a problem that the photosensitive layer is detached during offset printing and the number of printed sheets cannot be increased.

Various methods have been proposed as methods for improving the electrostatic properties of the photoconductive layer. One of the methods 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 a dicarboxylic acid. And JP-B-42-6878 and JP-B-45-3073. However, even the photosensitive materials improved by these methods do not have sufficient electrostatic characteristics, and no material having particularly excellent light attenuation characteristics has been obtained. Therefore, in order to improve the sensitivity shortage of this photosensitive material,
Conventionally, a method of adding a large amount of a sensitizing dye into the photoconductive layer has been adopted.However, the light-sensitive material produced by such a method significantly deteriorates whiteness and causes deterioration in quality as a recording medium. Causes deterioration of the dark decay of the photosensitive material,
There was a problem that a sufficient copied image could not be obtained.

On the other hand, Japanese Patent Application Laid-Open No. 60-10254 discloses a method in which the average molecular weight of the resin is adjusted and used as the binder resin used in the photoconductive layer. That is, by using an acrylic resin having an acid value of 4 to 50 and a component having an average molecular weight of 10 ³ to 10 ⁴ and a component having a distribution of 10 ⁴ to 2 × 10 ⁵ , the electrostatic properties (particularly,
A technique for improving the reproducibility of the PPC photoreceptor and the moisture resistance is described.

Furthermore, research on a lithographic printing original plate using an electrophotographic photoreceptor has been earnestly conducted, and a binder resin for a photoconductive layer having both electrostatic characteristics as an electrophotographic photoreceptor and printing characteristics as a printing original plate. For example, in Japanese Patent Publication No. 50-31011,
Copolymerized with (meth) acrylate monomer and other monomers in the presence of fumaric acid, Tg 10-80 at Mw 1.8-10 × 10 ⁴
C. and a copolymer comprising a (meth) acrylate monomer and a monomer other than fumaric acid. JP-A-53-54027 discloses that a carboxylic acid group is formed by forming at least an atom from an ester bond. Those using a terpolymer containing a (meth) acrylic ester having a substituent which is located at a distance of several sevens, and those disclosed in JP-A-54-20735 and JP-A-57-20254.
No. 4 uses a quaternary or pentameric copolymer containing acrylic acid and hydroxyethyl (meth) acrylate,
JP-A-58-68046 discloses a method using a terpolymer containing a (meth) acrylate ester having an alkyl group having 6 to 12 carbon atoms as a substituent and a carboxylic acid-containing vinyl monomer. It is described that it is effective in improving the desensitizing property of the layer.

(Problems to be Solved by the Invention) However, even if the above-mentioned resin is said to be effective for the electrostatic property, the moisture resistance property, and the durability, it is particularly difficult to evaluate the chargeability and the dark charge when actually evaluated. There were problems with the holding properties, the electrostatic properties of photosensitivity, the smoothness of the photoconductive layer, and the like, which were not practically satisfactory.

Also, a binder resin developed as an electrophotographic lithographic printing plate precursor has a problem in the above-mentioned electrostatic characteristics, background contamination of printed matter, etc. when actually evaluated.

The present invention is to solve the above-mentioned problems of the conventional electrophotographic photoreceptor.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a high-quality electrophotographic photoreceptor having improved electrostatic characteristics (particularly dark charge retention and photosensitivity) and reproducing a copied image faithful to an original image.

Another object of the present invention is to provide an electrophotographic photoreceptor having a clear and high-quality image even when the environment at the time of forming a copy image fluctuates such as low temperature and low humidity or high temperature and high humidity.

Another object of the present invention is to provide an electrophotographic lithographic printing plate precursor having excellent electrostatic properties (particularly dark charge retention and light sensitivity),
An object of the present invention is to provide a lithographic printing original plate that reproduces a copied image faithful to an original image and does not generate not only a uniform background stain but also a dot-like background stain on a printed matter.

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

(I) Resin [A] having a weight average molecular weight of 3 × 10 ^{3 to} 9 × 10 ³ and -PO
₃ H ₂ group, a copolymerization component containing at least one acidic group selected from -COOH group and -SO ₃ H groups 0.05 to 20 wt%
Resin (ii) Resin [B] having a weight average molecular weight of 3 × 10 ⁴ to 10 ⁵ and selected from an OH group, an amino group represented by the following general formula (II) and a nitrogen-containing heterocyclic group A resin containing 0.05 to 15% by weight of a copolymer component containing at least one group to be obtained.

General formula (II) In the formula (II), R ₁ and R ₂ may be the same or different, and each represents a hydrogen atom, an optionally substituted alkyl group, an optionally substituted alkenyl group, an optionally substituted aralkyl group, an alicyclic group. Represents a formula group or an optionally substituted aryl group.

That is, the binder resin used in the present invention is a low-molecular-weight resin [A] containing an acidic group and an OH group, an amino group represented by the general formula (II) or a nitrogen-containing heterocyclic group (hereinafter, referred to as “A”). A high molecular weight resin [B] containing OH groups and / or basic groups).

The acidic group contained in the resin (A), -PO ₃ H group,
—COOH groups and / or —SO ₃ H groups.

The proportion of the copolymer component containing the acidic group is determined by the resin [A]
0.05 to 20% by weight, more preferably 0.5 to 10% by weight.
% By weight. The weight average molecular weight of the resin [A] is 3 × 10 ³
９9 × 10 ³ .

The glass transition point of the resin (A) is preferably -10 ° C to 100 ° C.
° C range, more preferably -5 ° C to 80 ° C.

Resin [B] has a proportion of a copolymer component containing -OH group and / or basic group of 0.05 to 15% by weight in resin [B], and more preferably 0.5 to 10% by weight. . The weight average molecular weight of the resin [B] is 3 × 10 ⁴ to 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.

In the present invention, the resin [A] is adsorbed on the acidic group contained in the resin and the stoichiometric defect of the inorganic photoconductor, and is a low molecular weight substance. In addition, while improving trapping of the photoconductor and improving the humidity characteristics, the dispersion of the photoconductor is sufficiently performed to suppress aggregation.

The resin [B] sufficiently increases the mechanical strength of the photoconductive layer, which is insufficient with the resin [A] alone.

If the content of the acidic group in the resin [A] is less than 0.05% by weight, the initial potential is too low to obtain a sufficient image density. On the other hand, when the content of the acidic group is more than 20% by weight, dispersibility decreases, film smoothness and high-humidity characteristics of electrophotographic characteristics decrease, and background contamination increases when used as an offset master. Absent.

In the present invention, the -OH group component or the 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 considered that this has the effect of improving the film strength after forming the film. However, when the proportion of these components in the resin [B] exceeds 15% by weight, the composition is affected by moisture, and the moisture resistance of the photoconductive layer is reduced.

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 are sufficiently adsorbed and the surface of the particles can be covered, so that the photoconductive layer has a smooth surface. Although good image quality without stains and background can be obtained in terms of properties and electrostatic characteristics, the film strength is not yet sufficient, and satisfactory results in durability cannot be obtained.

On the other hand, even when the electrophotographic photoreceptor of the present invention is used as an electrophotographic lithographic printing plate precursor, the surface of the photoconductor layer has good smoothness, and the photoconductor zinc oxide particles are contained in the binder. Since the dispersion is sufficiently dispersed, when the desensitizing treatment is performed with the desensitizing treatment liquid, the non-image area is uniformly and sufficiently hydrophilicized, and the adhesion of the printing ink to the non-image area during printing is suppressed, and 10,000. Even when a large number of printed materials such as sheets are printed, background smearing does not occur.

As the resin [A] and the resin [B], conventionally known resins can be used as long as they have the above-mentioned physical properties. 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, an example of the resin [A] is 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. 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 'has 1 to 1 carbon atoms
18 optionally substituted alkyl groups (for example, methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl, decyl, dodecyl, tridecyl, tetradecyl, 2-methoxyethyl Group, 2-
Ethoxyethyl group, 2-chloroethyl group, etc.), carbon number 2
-18 optionally substituted alkenyl groups (for example, vinyl group, allyl group, isopropenyl group, butenyl group, hexenyl group, heptenyl group, octenyl group, etc.), which may be substituted with 7 to 12 carbon atoms. Aralkyl groups (for example, benzyl group, phenethyl group, methoxybenzyl group, ethoxybenzyl group, methylbenzyl group, etc.), and optionally substituted cycloalkyl groups having 5 to 8 carbon atoms (for example, cyclopentyl group, cyclohexyl group, cycloheptyl group) And the like, an aryl group (eg, phenyl, tolyl, xylyl, mesityl, naphthyl, methoxyphenyl, ethoxyphenyl, chlorophenyl, dichlorophenyl, etc.).

The "copolymer component containing an acidic group" contained in the resin [A] of the present invention may be any vinyl compound containing the acidic group which can be copolymerized with the general formula (I).
For example, it is described in “Polymer Data Handbook [Basic Edition]” edited by The Society of Polymer Science, Baifukan (1986). Specifically, acrylic acid, α- and / or β-substituted acrylic acid (for example, α-acetoxy form, α-acetoxymethyl form,
α-chloro, α-bromo, α-chloro, α-tributylsilyl, α-cyano, β-chloro, β-bromo, α-chloro-β-methoxy, α, β-dichloro Methacrylic acid, itaconic acid, itaconic acid half-esters, itaconic acid semi-amides, crotonic acid, 2-alkenylcarboxylic acids (eg, 2-pentenoic acid, 2-methyl-2-hexenoic acid, 2-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, vinylsulfonic acid, vinylphosphonic acid, dicarboxylic acid Half-ester derivatives of vinyl or allyl groups of acids,
And carboxylic acid or sulfonic acid ester derivatives and amide derivatives containing the acidic group in the substituent.

The “copolymerization component containing an —OH group and / or a basic group” contained in the resin [B] is a vinyl compound containing the substituent capable of copolymerizing with the general formula (I). Any may be used. As the basic group, for example, a compound represented by the general formula (II)
And a heterocycle containing a nitrogen atom and a nitrogen atom.

General formula (II) In the formula (II), R ₁ and R ₂ may be the same or different and each represents a hydrogen atom, an alkyl group which may be substituted (for example, a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group, an octyl group) Decyl group, dodecyl group, tetradecyl group, octadecyl group, 2-chloroethyl group, 2-bromoethyl group, 2-chloroethyl group, 2-hydroxyethyl group, 2-cyanoethyl group, 2-methoxyethyl group, 3-
An ethoxypropyl group, etc.), an optionally substituted alkenyl group (eg, allyl group, isopropenyl group, 4-butenyl group, etc.), an optionally substituted aralkyl group (eg, benzyl group, phenethyl group, chlorobenzyl group, A methylbenzyl group, a methoxybenzyl group, a hydroxybenzyl group, etc.), an alicyclic group (eg, cyclopentyl group, cyclohexyl group, etc.), an optionally substituted aryl group (eg, phenyl group, tolyl group, xylyl group, mesityl group, Butylphenyl group, methoxyphenyl group, chlorophenyl group,
Etc.).

Further, as the nitrogen-containing heterocyclic ring, the nitrogen atom is 1 to
Heterocycles consisting of a 5- to 7-membered ring containing three rings may be mentioned, and these heterocycles may further be formed by forming a condensed ring with a benzene ring, a naphthalene ring or the like. Further, these rings may contain a substituent. Specifically, for example, a pyrrole ring, imidazole ring, pyrazole ring, pyridine ring, piperazine ring, pyrimidine ring, pyridazine ring, indolizine ring, indole ring, 2H-pyrrole ring, 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, imidazoline ring, pyrazolidine ring, virazoline 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 Oxazole ring, selenazole ring, benzoselenazole ring, naphthoselenazole ring, oxazoline ring, isoxazole ring, benzoxazole ring, morpholine ring, pyrrolidone ring, triazole ring,
Examples include a benzotriazole ring and a triazine ring.

These OH groups and / or basic groups may be substituted with an ester derivative or an amide derivative derived from a vinyl group-containing carboxylic acid or sulfonic acid as exemplified for the acidic group-containing vinyl compound of the resin [A]. The desired monomer can be obtained by including the compound in the group. For example, 2-hydroxyethyl methacrylate, 3-hydroxypropyl methacrylate, 3-hydroxy-2-chloropropyl methacrylate, 4-hydroxybutyl methacrylate, 6-hydroxyhexyl methacrylate, 10-hydroxydecyl methacrylate, N- (2-hydroxyethyl) acrylamide N- (3-hydroxypropyl) methacrylamide, N- (α, α-dihydroxymethylaminoethyl methacrylamide, N- (4-hydroxybutyl) methacrylamide, 2- (N, N-dimethylamino) ethyl methacrylate, 2- (N, N-diethylamino) ethyl methacrylate, 3- (N, N-dimethylamino) propyl methacrylate, 2- (N, N-dimethylamino) ethyl methacrylamide, hydroxystyrene,
Hydroxymethylstyrene, N, N-dimethylaminomethylstyrene, N, N-diethylaminomethylstyrene, N
And various monomers such as -butyl-N-methylaminomethylstyrene and N- (hydroxyphenyl) methacrylamide. Examples of the vinyl compound having a nitrogen-containing heterocyclic ring include the aforementioned “Polymer Data Handbook (Basic Edition)”, pp. 175-181, DATomalia, “Reacti
ve Heterocyclic Monomers ”Chap 1 of“ Functional Mo
nomers Vol.2 ", Marcel DeKKer Inc.NY (1974), LSL
uskin, “Basic Monomers”, Chap 3 of “Functional Mono”
mers Vol. 2 ", Marcel DeRRer Inc. NY (1974) and the like.

Further, the resin [A] and the resin [B] of the present invention may contain other monomers as copolymerization components in addition to the above-mentioned monomers. For example, α-olefin acid,
Examples include vinyl alkanoate or allyl esters, acrylonitrile, methacrylonitrile, vinyl ethers, acrylamides, methacrylamides, styrenes, and heterocyclic vinyls (eg, vinyl thiophene, vinyl dioxane, vinyl oxazine, etc.).

Further, in addition to the resins [A] and [B] of the present invention, other resins can be used in combination. As those resins,
Examples include alkyd resins, polybutyral resins, polyolefins, ethylene-vinyl acetate copolymers, styrene resins, styrene-butadiene resins, acrylate-butadiene resins, vinyl alkanoate resins, and the like.

Other resins other than these present resins [A] and [B]
30% of the total amount of binder resin containing the resin of the present invention (weight ratio)
When the value exceeds, the effect of the present invention (especially, improvement in electrostatic characteristics) is lost.

The ratio of the amount of the resin [A] and [B] used in the present invention depends on the type, particle size, and surface state 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
6060 to 85-40 (weight ratio).

The ratio of the weight average molecular weight of the resin [A] and the resin [B] is 1.
Two or more are preferred. More preferably, it is 2.0 or more.

Examples of the inorganic photoconductive material used in the present invention include zinc oxide, 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 as spectral sensitizers as needed. For example, Harumi Miyamoto, Hidehiko Takei, Imaging 1973 (No.8), page 12, CJ Young, etc., RCA
Review 15 , 469 (1954), Kohei Kiyota, IEICE Transactions J 63-C (No.2), 97 (1980), Yuji Harasaki, etc.
Carbonium dyes, diphenylmethane dyes, triphenylmethane dyes, xanthene dyes, phthalein dyes, and polymethine as reviewed in Industrial Chemistry Magazine 66 78 and 188 (1963), Tadaaki Tani, Photographic Society of Japan 35 , 208 (1972), etc. Dyes (eg, oxanol dyes, merocyanine dyes,
Cyanine dye, rhodacyanine dye, styryl dye, etc.),
And a phthalocyanine dye (which may contain a metal).

More specifically, those using mainly carbonium dyes, triphenylmethane dyes, xanthene dyes, and phthalein dyes are described in JP-B-51-452,
-90334, JP-A-50-114227, JP-A-53-39130,
JP-A-53-82353, U.S. Pat. No. 3,052,540, U.S. Pat. No. 4,054,450, and JP-A-57-16456 are examples.

Oxonol dyes, merocyanine dyes, cyanine dyes, polymethine dyes such as rhodacyanine dyes, F.
M. Harmmer `` The Cyanine Dyes and Related Compound
s '' 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. Patent No.3,121,008, U.S. Patent No.3,125,447, U.S. Patent No.3,128,179, U.S. Patent No.3,132,942, U.S. Patent No.3,622,317, U.K. Patent No.1,226,892, U.K. Patent No.1,
No. 309,274, British Patent No. 1,405,898, JP-B-48-7814
And JP-B-55-18892.

Further, 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, JP-A-47-44180, JP-B-51-41061, 1949-5034
No., JP-A-49-45122, JP-A-57-46245, JP-A-56
No. -35141, JP-A-57-157254, JP-A-61-26044,
JP-A-61-27551, U.S. Pat.No. 3,619,154, U.S. Pat.No.4,175,956, `` Research Disclosure '' 1982, 21
6, pages 117 to 118 and the like. The photoreceptor of the present invention is excellent in that even when various sensitizing dyes are used in combination, the performance is hardly changed by the sensitizing dye. Furthermore, various conventionally known additives for an electrophotographic photosensitive layer such as a chemical sensitizer can be used in combination, if necessary.
For example, the review mentioned above: Imaging 1973 (No. 8) No. 12
The electron accepting compounds (for example, halogen,
Benzoquinone, chloranil, acid anhydride, etc.), Hiroshi Komon, etc.
"Recent development and commercialization of photoconductive materials and photoconductors" Chapter 4-
Chapter 6: Polyarylalkane compounds, hindered phenol compounds, p-phenylenediamine compounds, and the like described in the review section of Japan Science Information Co., Ltd. Publishing Division (1986).

The amounts of these various additives are not particularly limited, but are usually 0.0001 to 2.0 parts by weight based on 100 parts by weight of the photoconductor.

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

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

In some cases, an insulating layer is provided for the main purpose of protecting the photoreceptor, improving durability, and improving dark attenuation characteristics. At this time, the insulating layer is set relatively thin, and the insulating layer provided when the photosensitive member is used in a specific electrophotographic process is set relatively thick.

In the latter case, the thickness of the insulating layer is between 5 and 70 μm, especially 10
Set to ~ 50μ.

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

As the resin used for forming the insulating layer or the charge transport layer, typical ones are polystyrene resin, polyester resin, cellulose resin, polyether resin, vinyl chloride resin, vinyl acetate resin, vinyl chloride-copolymer resin, A thermoplastic resin of a polyacryl resin, a polyolefin resin, a urethane resin, an epoxy resin, a melamine resin, a silicone resin, and a curable resin are appropriately used.

The photoconductive layer according to the present invention can be provided on a conventionally known support. Generally, the support of the electrophotographic photosensitive layer is preferably conductive. As the conductive support, a base material such as a metal, paper, or a plastic sheet is impregnated with a low-resistance substance in the same manner as in the related art. The above-mentioned substrate is subjected to a conductive treatment, for example, a substrate coated with at least one or more layers 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 support provided with a water-resistant adhesive layer on the surface thereof, a support provided with at least one or more precoat layers as required on the surface layer of the support, and a base conductive plastic on which Al or the like is deposited on paper. Can be used.

Specifically, as an example of a conductive substrate or a conductive material, Yukio Sakamoto, Electrophotography, 14, (No. 1), p2-11 (197)
5), Hiroyuki Moriga, “Chemistry of Introductory Special Papers” Polymer Publishing Association (1
975), MF Hoover, J. Macromol. Sci. Chem. A-4 (6),
Those described in pages 1327 to 1417 (1970) and the like are used.

(Examples) Embodiments of the present invention will be illustrated below, but the contents of the present invention are 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 heated to 2,2′-azobis (2,4-dimethylvaleronitrile).
6 g was added and reacted for 10 hours.

The weight average molecular weight of the obtained copolymer [A] -1 is 7800
And 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, 0.5 g of azobisisobrotylonitrile was added, and the mixture was reacted for 10 hours. . The obtained copolymer [B] -1 had a weight average molecular weight of 62,000 and a glass transition point of 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 a temperature of 70 ° C. under a nitrogen stream, and 0.5 g of azobisisobutyronitrile was added, followed by a reaction for 10 hours. The weight average molecular weight of the obtained copolymer [C] -1 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 0.5 g of azobisisobutyronitrile was added, followed by a reaction for 10 hours. The weight average molecular weight of the obtained copolymer [C] -2 was 61,000.

Example 1 10 g (as a solid content) of the resin [A] -1 produced in Synthesis Example 1 and 30 g of the resin [B] -1 produced in Synthesis Example 2
(As solid content), zinc oxide 200g, Rose Bengal 0.
A mixture of 05 g and 300 g of toluene was dispersed in a ball mill for 2 hours to prepare a photosensitive layer-formed product, which was applied to a conductive-treated paper with a wire bar so that the dry adhesion amount was 22 g / m ² , Dry at 110 ° C for 1 minute, then in darkness at 20 ° C 65% RH
Was left for 24 hours under the above conditions to produce an electrophotographic photosensitive material.

Comparative Example A Resin [A]-used as binder resin in Example 1
Instead of 1 and [B] -1, only resin [A] -1 was used for 40
An electrophotographic photosensitive material A was produced in the same manner as in Example 1 except that g (as the solid content) was used.

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

Comparative Example C An electrophotographic photosensitive material C was produced in the same manner as in Example 1, except that only 40 g (as a solid content) of the resin [C] -2 produced in Synthesis Example 4 was used as the binder resin.

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

The film properties (surface smoothness), film strength, electrostatic properties, imaging properties of these photosensitive materials, and the imaging properties when the environmental conditions were set to 30 ° C. and 80% RH were examined. Further, when these photosensitive materials are used as an offset master, the photoconductive desensitizing property (expressed by the contact angle of the photoconductive layer with water after the desensitizing treatment) and printability (ground stain, Printing durability).

The imaging property and printability are as follows: Fully automatic plate making ELP404V (manufactured by Fuji Photo Film Co., Ltd.) is exposed and developed using ELP-T as a developer to form an image, and a desensitizing liquid ELP-E is used. It was examined using a lithographic printing plate obtained by etching with an etching processor (a Hamadastar 800SX model manufactured by Hamadastar Co., Ltd. was used as a printing machine).

 Table 1 summarizes the above results.

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

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

Note 2) the mechanical strength of the photoconductive layer: obtained emery paper in those Nitaira 50 g / cm ² of the photosensitive material surface work to Haydon -14 type surface property test material (manufactured by Shinto Scientific Co.) ( (# 1000) was repeated 1000 times to remove the abrasion powder, and the remaining film ratio (%) was determined from the weight loss of the photosensitive layer to determine the mechanical strength.

Note 3) Electrostatic properties: Paper analyzer (Kawaguchi Electric Co., Ltd. paper analyzer) in a dark room at a temperature of 20 ° C and 65% RH.
After the 20 seconds corona discharge -6kV with SP-428 type), allowed to stand for 10 seconds to measure the surface potential V ₁₀ at this time.
Next, the potential V ₇₀ after standing still in the dark for 60 seconds was measured, and the potential retention after dark decay for 60 seconds, that is, the dark decay retention rate [DRR (%)] was determined as [V ₇₀ / V ₁₀ ) × 100 (%).

After charging the surface of the photoconductive layer to −400 V by corona discharge, irradiate the surface of the photoconductive layer with visible light having an illuminance of 2.0 lux, and determine the time until the surface potential (V ₁₀ ) attenuates to 1/10. From this, the exposure amount E _1/10 (looks / second) is calculated.

Note 4) Image-capturing: Copy images (fog, image) obtained by leaving each photosensitive material for one day and night under the following environmental conditions and making a plate using 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 were 20 ° C 65% RH and 30 ° C 80% RH.

Note 5) Contact angle with water: Using each photosensitive material and desensitizing solution ELP-E (manufactured by Fuji Photo Film Co., Ltd.), apply 1 to the etching processor.
After passing through the surface to desensitize the surface of the photoconductive layer, a drop of 2 μm of distilled water is placed thereon, and the contact angle with the formed water is measured with a goniometer.

Note 6) Background stain on printed matter: Each photosensitive material is made into a plate using a fully automatic plate-making machine ELP404V (manufactured by Fuji Photo Film Co., Ltd.) to form a toner image, and desensitized under the same conditions as above (Note 3). This is used as an offset master and an offset printing machine (Hamaduster Co., Ltd.)
500 sheets on high-quality paper using a HAMADASTAR 800SX, and visually check for soiling of all printed matter. This is referred to as background smear I of the printed matter.

The background smear II of the printed matter is tested in the same manner as the background smear I except that the desensitizing solution is diluted 5 times and the dampening solution for printing is diluted 2 times. The case of II corresponds to printing under more severe conditions than I.

Note 7) Printability: Indicates the number of sheets that can be printed without causing any problem in background stains in non-image areas and image quality of image areas when each photosensitive material is processed under the evaluation conditions of print smear I described in Note 6). (The greater the number of prints, the better the printing durability).

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, the actual copied image had no background fog, and the copied image quality was clear. This is presumed to be due to the photoconductor and the binder resin being sufficiently adsorbed and covering the back surface of the particles.

For the same reason, even when used as an offset master master, the desensitizing treatment with the desensitizing treatment solution proceeds sufficiently, and the contact angle with water of the non-image area is 15 ° or less and is sufficiently hydrophilized. I have. Even when the printed matter was actually printed and the background stain was observed, no stain was observed. However, Comparative Example A
In the case of (2), when the strength test and the printing durability test of the photoconductive layer were performed, the film strength was not sufficient, and a serious problem occurred in durability. On the other hand, in the case of the resin used in Comparative Example B, the agglomerated state proceeded to such an extent that the dispersion for forming a photosensitive layer could not be adjusted. In Comparative Example C, in which a photosensitive material was prepared using only an acid component-containing high molecular weight material, the electrostatic properties were good, but the smoothness of the photoconductive layer was reduced, and when used as an offset master, the printed material was severely soiled and could not be used. It has become something. Further, the imaging performance at high temperature and high humidity was deteriorated. Comparative Example D
Sufficient performance was not obtained in both electrostatic characteristics and printing characteristics.

This is considered to indicate that satisfactory performance cannot be obtained if the interaction between the photoconductor and the binder is too strong or too weak.

As described 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 master.

Examples 2 to 15 Copolymers shown in Table 2 as Resin [A] were produced in the same manner as in the production conditions of Resin [A] -1 produced in Synthesis Example 1.

A photosensitive material was prepared in the same manner as in Example 1 except that 10 g (as solid content) of each of these resins [A] and 130 g (as solid content) of the resin [B] -1 produced in Synthesis Example 2 were used. Was manufactured.

In the same manner as in Example 1, the obtained photosensitive materials were evaluated for the smoothness of the photoconductive layer surface, the film strength, the electrostatic properties, and the printing properties when used as an offset master master. As a result, each of the photosensitive materials exhibited performance equal to or higher than that of the photosensitive material of Example 1.

That is, each of the photosensitive materials of the present invention is excellent in chargeability, dark charge retention rate, and photosensitivity, and the actual copied image can be ground fog even under severe conditions of high temperature and high humidity (30 ° C. and 80% RH). A clear image with no occurrence was obtained. In addition, when offset printing was performed as an offset master, a clear image-printed matter free of background fog was obtained even after printing 10,000 sheets.

Example 16 and Comparative Example E A mixed solution of 48.5 g of ethyl methacrylate, 48.5 g of benzyl methacrylate, 3 g of methacrylic acid and 200 g of toluene was heated to a temperature of 105 ° C. under a nitrogen stream, and 10 g of azobisisobutyronitrile was added. For 8 hours.

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

Example 1 20 g (as solid content) of the obtained copolymer
A mixture of 20 g of the resin [B] -1 prepared in the above, 200 g of zinc oxide, 0.02 g of a heptamethine cyanine dye represented by the following structural formula, 0.15 g of phthalic anhydride and 300 g of toluene was dispersed in a ball mill for 2 hours and exposed to light. The layer formation was adjusted. The following operations were performed in the same manner as in Example 1 to produce an electrophotographic photosensitive material.

Comparative photosensitive material E A mixed solution of 48.5 g of ethyl methacrylate, 48.5 g of benzyl methacrylate, 3 g of methacrylic acid and 200 g of toluene was heated to a temperature of 70 ° C. under a nitrogen stream, and 1.0 g of azobisisobutyronitrile was added. Allowed to react for hours.

The weight average molecular weight of the obtained copolymer was 36,000, and the glass transition point was 54 ° C. Comparative photosensitive material E was obtained in the same manner as in Example 16, except that only 40 g (as solid content) of a copolymer as a binder resin was used.

The electrostatic characteristics 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 a light source. The results are shown in Table-3.

Comparative Example E had poor smoothness and dark charge retention (DR
R) decreased markedly (apparently E _1/10 was small,
The high light sensitivity is due to the large DRR.) The DRR is further deteriorated as compared with Comparative Example C. This indicates that conventionally known resins have a problem that they are remarkably affected by the type of spectral sensitizing dye used in combination. On the other hand, the binder resin of the present invention provides a photosensitive material which is extremely excellent in chargeability, dark charge retention and photosensitivity even if the chemical structure of the spectral sensitizing dye is greatly changed.

Examples 17 to 28 Synthesis examples 2 of the copolymers shown in Table 4 as resin [B]
Each was manufactured under the same conditions as shown in the above.

Resin [A] and resin [B] were used in the combinations shown in Table 5 and 20 g of resin [A] and 20 g of resin [B] (each as a solid content). Materials were made. The electrostatic properties of each photosensitive material were measured in the same manner as in Example 16, 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 all of the smoothness and strength of the photoconductive layer, the electrostatic properties, the image-capturability, and the background stain and printing durability of the printed matter. Is obtained.

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

 ──────────────────────────────────────────────────続 き Continued on the front page (56) References JP-B-46-40912 (JP, B1) JP-B-44-6394 (JP, B1) JP-B-48-34183 (JP, B1)

Claims (1)

(57) [Claims] An electrophotographic photoreceptor having a photoconductive layer containing at least an inorganic photoconductive material and a binder resin, wherein the binder resin comprises 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 3 × 10 ^{3 to} 9 × 10 ³ and —PO ₃ H
₂ group, -COOH group and -SO ₃ at least one copolymerizable components 0.05 to 20 wt% containing a resin containing an acidic group from the H group are selected. (Ii) Resin [B] having a weight average molecular weight of 3 × 10 ⁴ to 10 ⁵ and at least one selected from an OH group, an amino group represented by the following general formula (II), and a nitrogen-containing heterocyclic group: A resin containing 0.05 to 15% by weight of a copolymer component containing one type of group. General formula (II) In the formula (II), R ₁ and R ₂ may be the same or different, and each represents a hydrogen atom, an optionally substituted alkyl group, an optionally substituted alkenyl group, an optionally substituted aralkyl group, an alicyclic group. Represents a formula group or an optionally substituted aryl group.