JPH07117757B2 - 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),
Acrylic resin (Japanese Patent Publication No. 35-11216), acrylic acid ester copolymer (eg Japanese Patent Publication No. 35-11219, Japanese Patent Publication No. 36-8510)
No., 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 with the photoconductive layer is Japanese Patent Publication No. 42-6878 and Japanese 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 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) are increased. 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 motomer other than fumaric acid, and in JP-A-53-54027, a carboxylic acid group is separated from an 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 are problems with the properties, the electrostatic characteristics of photosensitivity, the smoothness of the photoconductive layer, and the like, which are not satisfactory in practice.

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 the Problems) The above-mentioned problems in an electrophotographic photoreceptor having a photoconductive layer containing at least an inorganic photoconductive material and a binder resin,
The binder resin contains at least one of the following resin [A] and resin [B], and is solved by an electrophotographic photoreceptor.

(I) Resin (A); 10 ^3-310 has a weight average molecular weight of ^4, and -PO ₃ H ₂ group,
Resin comprising at least one acidic group selected from --SO ₃ H group and --COOH group bonded only to the terminal of the polymer main chain (ii) Resin [B]; 10 ^{4 to} 5 × 10 ⁵ weight has an average molecular weight, and has a pKa greater than pKa of the acid groups contained in the resin (a) used in _{combination, -PO 3 H 2, -SO 3} H, -COOH and (R represents a hydrocarbon group) A resin containing a copolymerization component containing at least one acidic group selected from the following: That is, the binder resin used in the present invention contains at least one of the above acidic groups. A low molecular weight resin [A] which is not contained in the side chain linked to the polymer main chain and is bonded only to the end of the main chain
And a high molecular weight resin [B] containing an acidic group having a larger pKa than this as a side chain of the copolymerization component.

The range of the weight average molecular weight of the resin [A] is preferably 5 ×
It is 10 ^{3 to} 1.5 × 10 ⁴ , and the abundance ratio of the acidic group in the polymer is preferably 0.1 to 20% by weight per unit weight part.

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

The weight average molecular weight of the resin [B] is preferably 3 × 10 ⁴ to 2 × 10 ⁵ .

The acidic group contained in the polymer side chain of the resin "B" is preferably contained in the resin "B" in a proportion of 0.05 to 5% by weight, and particularly preferably the combination of Table-A below. The glass transition point of the resin [B] is preferably in the range of 0 ° C to 120 ° C, more preferably 0 ° C to 100 ° C. More preferably, it is 10 ° C to 80 ° C.

The conventionally known binder resin containing an acidic group as described above is mainly used for an offset master 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 low molecular weight binder resin [A] used in the present invention is a polymer in which the acidic group contained in the resin is bonded to the end of the main chain. It is a combination with a contained resin.

In the present invention, the polymer-containing acidic group portion of the resin [A] is adsorbed to the stoichiometric defects of the inorganic photoconductor and is a low molecular weight substance, so that the surface coverage of the photoconductor is improved. By improving the above, while compensating for the trap of the photoconductor and improving the humidity characteristic, the photoconductor is sufficiently dispersed and aggregation is suppressed.

The resin [B] exhibits a very weak interaction with the photoconductor particles as compared with the resin [A], has a function of gently covering, and does not deviate from the function of the resin [A] at all. The resin [A] alone is sufficient to make the mechanical strength of the photoconductive layer insufficient.

The content of the terminal acidic group in the resin [A] is per part by weight.
If it is less than 0.5% by weight, the initial potential is low and a sufficient image density cannot be obtained. On the other hand, the acidic content is 20
If it exceeds 5% by weight, dispersibility decreases, film smoothness and high humidity characteristics such as electrophotographic characteristics decrease, and further, when used as an offset master, scumming increases, which is not preferable.

Further, if the content of the side chain acidic group in the resin [B] exceeds 5% by weight, the resin [B] is adsorbed to the photoconductor particles, the dispersion of the photoconductor is destroyed, and the agglomerates or precipitates are generated. If the coating film is not formed, or if the coating film is formed, the electrostatic properties of the obtained photoconductor are significantly deteriorated, and the smoothness of the surface of the photoconductor is reduced. Becomes coarse and the strength against mechanical wear deteriorates, which is not preferable.

When a photoconductor having a rough surface of the photoconductive layer is used as an electrophotographic lithographic printing plate, the dispersion state of the zinc oxide particles as the photoconductor and the binder resin is not appropriate, and in the presence of aggregates. Since the photoconductive layer is formed, even if the desensitizing treatment with the desensitizing treatment liquid is not performed, the non-image area is not sufficiently hydrophilicized, causing the printing ink to adhere during printing, resulting in non-printing. The image area is stained.

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. The film has good properties and electrostatic characteristics, and an image quality without scumming can be obtained, but the film strength is still insufficient and satisfactory results cannot be obtained in 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.

In resin [B] In the group, R is more specifically, for example, having 1 to 12 carbon atoms.
An optionally substituted alkyl group (for example, a methyl group,
Ethyl group, propyl group, butyl group, hexyl group, octyl group, decyl group, dodecyl group, 2-chloroethyl group, 2
-Methoxyethyl group, 2-ethoxyethyl group, 3-methoxypropyl group, etc.), aralkyl group having 7 to 12 carbon atoms and optionally substituted (eg, benzyl group, phenethyl group,
A chlorobenzyl group, a methoxybenzyl group, a methylbenzyl group, etc.), an optionally substituted alicyclic group having 5 to 8 carbon atoms (eg, cyclopentyl group, cyclohexyl group, etc.) or an optionally substituted aryl group (eg, Phenyl group, tolyl group, xylyl group, mesityl group, naphthyl group,
A chlorophenyl group, a methoxyphenyl group, etc.).

The resins [A] and [B] may be any of the conventionally known resins as long as they have the above-mentioned physical properties, for example, polyester resin, modified epoxy resin, silicone resin, olefin resin, polycarbonate resin, vinyl alkanoate resin,
Allyl alkanoate resin, modified polyamide resin, phenol resin, fatty acid modified alkyd resin, acrylic resin and the like are used.

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

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, a 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, etc.), having 2 to 18 carbon atoms Alkenyl group which may be substituted (for example, vinyl group, allyl group, isopropenyl group, butenyl group, hexenyl group, heptenyl group,
Octenyl group, etc.), optionally substituted aralkyl group having 7 to 12 carbon atoms (eg, benzyl group, phenethyl group, methoxybenzyl group, ethoxybenzyl group, methylbenzyl group, etc.), substituted having 5 to 8 carbon atoms Optionally a cycloalkyl group (eg, cyclopentyl group, cyclohexyl group, cycloheptyl group, etc.), aryl group (eg, phenyl group, tolyl group, xyl group, mesityl group, naphthyl group,
Methoxyphenyl group, ethoxyphenyl group, chlorophenyl group, dichlorophenyl group, etc.).

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).

As the "copolymer component containing an acidic group" in the resin [B] of the present invention, any vinyl compound containing an acidic group copolymerizable with the above-mentioned general formula (I) can be used. it can. For example, it is described in "Polymer Data Handbook [Basic Basics]", edited by Japan 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- (2-aminomethyl form, α-chloro form, α-bumoro form, α- Fluoro body, α-tributylsilyl body, α-cyano body, β-chloro body, β-bromo body,
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 (eg 2-pentenoic acid) , 2-methyl-2-hexenoic acid, 2-octenoic acid, 4-methyl-2-
Hexenic 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, vinyl of dicarboxylic acids Group or allyl group half ester derivative, and ester derivative of these carboxylic acid or sulfonic acid,
Examples thereof include compounds containing the acidic group in the substituent of the amide derivative.

Further, each of the resins [A] and [B] of the present invention contains a monomer of the general formula (I) and a monomer containing an acidic group in the resin [B] together with other monomers. A monomer may be contained as a copolymerization component.

For example, α-olefins, vinyl alkanoates or allyl esters, acrylonitrile, methacrylonitrile, vinyl ethers, acrylamides, methacrylamides, styrenes, heterocyclic vinyls (eg vinylpyrrolidone, vinylpyridine, vinylimidazole, vinylthiophene). , Vinylimidazoline, vinylthiophene, vinylimidazoline, vinylpyrazole, vinyl-
Dioxane, vinylquinoline, vinylthiazole, vinyl-oxazine, etc.) and the like.

Further, other resins may be used in combination with the resins [A] and [B] of the present invention. Examples of such resins include alkyd resins, polybutyral resins, polyolefins, ethylene-acid vinyl copolymers, styrene resins, styrene-butadiene resins, acrylate-butadiene resins, vinyl alkanoate resins, and the like.

The above-mentioned other resin is the total binder resin amount using the resin of the present invention.
If it exceeds 30% (weight ratio), the effect of the present invention (in particular, improvement of electrostatic properties) is lost.

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 resin [A] and the resin [B] are used. The ratio is 5 to 80:95 to 20 (weight ratio), preferably
It is 15-60: 85-40 (weight ratio).

The weight average molecular weight ratio of the resin [A] and the resin [B] is preferably 1.2 or more, and 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, Journal of 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, Journal of the Japan Society of photographic Science and Technology 35, 208 (1972) carbonium-based dyes of review references such as,
Diphenylmethane dye, triphenylmethane dye, xanthene dye, phthalein dye, polymethylene dye (for example, oxonol dye, merocyanine dye, cyanine dye, rhodacyanine dye, styryl dye, etc.), phthalocyanine dye (may contain metal), etc. Can be mentioned.

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. Patent No. 3,047,384, U.S. Patent 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. 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 above-mentioned review article: Imaging 1973 (No. 8), page 12, etc. review electron-accepting compounds (eg halogen, benzoquinone, chloranil, acid anhydrides, organic carboxylic acids, etc.), Hiroshi Komon, et al. Development and Practical Use of Photoconductive Materials and Photoconductors "Chapters 4 to 6: Review of Japanese Science Information Co., Ltd. (1986), polyarylalkane compounds, hindered phenol compounds, p-phenylene Examples thereof include diamine compounds.

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, Polyacrylic resin, polyolefin resin, urethane resin, epoxy resin, melamine resin, silicone resin such as thermoplastic resin and curable resin 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
Up to those described in pages 1417 (1970) and the like are used.

(Examples) The embodiments of the present invention will be illustrated below, but the contents of the present invention are not limited thereto.

Example 1 and Comparative Examples A to C (Synthesis Example 1) A mixed solution of 95 g of ethyl acrylate, 200 g of toluene and 50 g of isopropyl alcohol was moistened to a temperature of 85 ° C under a nitrogen stream, and then 4,4'-azobis (4-cyano). Valeric acid)
5 g (abbreviated as ABCV below) was added and reacted for 10 hours.

The weight average molecular weight of the obtained copolymer (A-1) was 8,60.
0, the glass transition point was 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. Obtained copolymer (A-2)
Had a weight average molecular weight of 7,800 and a glass transition point of 45 ° C.

(Synthesis Example 3) 98 g of ethyl methacrylate, a monomer 2 having the following structure (A)
A mixed solution of g, 200 g of toluene and 30 g of isopropyl alcohol was humidified to a temperature of 85 ° C. under a nitrogen stream, 2.0 g of 2,2′-azobis (1-cyclohexanecarbonitrile) was added, and the mixture was reacted for 10 hours. The weight average molecular weight of the obtained copolymer (B-1) was 54,000 and the glass transition point thereof was 48 ° C.

(Synthesis Example 4) Ethyl methacrylate 97 g, acrylic acid 3 g and toluene 2
00 g of the mixed solution was reacted under the same conditions as in Synthesis Example 3 to obtain a copolymer (B-2) having a weight average molecular weight of 80,000. The glass transition point was 48 ° C.

Example 1 8 g (as solid content) of the copolymer (A-1) produced in Synthesis Example 1 and 32 g of the copolymer (B-1) produced in Synthesis Example 3
(As solid content), zinc oxide 200g, tetrabromophenol 0.03g, rose bengal 0.03g, maleic anhydride 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-forming material, which was applied to a conductively treated paper with a wire bar so that the dry adhesion amount was 25 g / m ² . It was dried at 110 ° C. for 1 minute. Then in the dark at 20 ℃, 65% R
An electrophotographic photosensitive member was produced by leaving it under the condition of H for 24 hours.

Comparative Example A Instead of the binder resins (A-1) and (B-1) used in Example 1, only the copolymer (A-1) produced in Synthesis Example 1 was used.
A comparative electrophotographic photosensitive member A was produced in the same manner as in Example 1 except that 40 g (as solid content) was used.

Comparative Example B Instead of the binder resins (A-1) and (B-1) used in Example 1, 40 g (as solid content) of only the copolymer (B-2) produced in Synthesis Example 4 was used. A comparative electrophotographic photosensitive member B was produced in the same manner as in Example 1 except that it was used.

Comparative Example C Instead of the binder resins (A-1) and (B-1) used in Example 1, the copolymer (A-2) produced in Synthesis Example (2).
Was used in the same manner as in Example 1 except that 8 g (as solid content) and 32 g (as solid content) of the copolymer (B-2) produced in Synthesis Example (4) were used. C was produced.

The imaging properties of these photosensitive materials were examined when the film properties (surface smoothness), electrostatic properties, imaging properties, and environmental conditions were 30 ° C and 80% RH.

Further, when these photosensitive materials are used as a master plate for the OFF-TO-MASTER, the photoconductive layer is desensitized (represented by the contact angle with water of the photoconductive layer after the desensitizing treatment) and printability (background stain). , Printing durability, etc.).

As for the imaging system and printability, fully automatic plate-making ELP404V (manufactured by Fuji Photo Film Co., Ltd.) was exposed and developed using the developer ELP-T to form an image, and the desensitizing liquid ELP-E was used. 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 type) for 6 seconds at 6kV corona discharge, then 1
It was left for 0 seconds, and the surface potential V ₁₀ at this time was measured. Then, the potential V ₇₀ was measured after standing still in the dark for 60 seconds, and 6
The potential retention after dark decay for 0 seconds, that is, the dark decay retention [DRR (%)] was determined by (V ₇₀ / V ₁₀ ) × 100 (%). Also, after charging the photoconductive layer surface to -400 V by corona discharge, the photoconductive layer surface is irradiated with visible light with an illuminance of 2.0 lux, and the time until the surface potential (V ₁₀ ) decays to 1/10 Then, the exposure dose E _1/10 (lux seconds) 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. It is presumed that this is because the photoconductor and the binder resin are sufficiently adsorbed, the particle surfaces are covered, and the interaction between the binders is also sufficiently maintained. 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 printed sheets exceeded 10,000. In Comparative Examples A and C, the number of printed sheets was lower than that of the light-sensitive material of the present invention. Further, in Comparative Example C, the DRR was deteriorated in the electrophotographic characteristics as compared with the material of the present invention.

In Comparative Example B, the smoothness of the photoconductive layer was remarkably poor, the electrophotographic characteristics were deteriorated, and the image quality of the copied image was also deteriorated. Also when used as an offset master, the non-image area was greatly varied in hydrophilicity, and scumming occurred on the printed matter after printing.

From the above, an electrophotographic photoreceptor 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, 200 g of toluene and 100 g of isopropyl alcohol 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 (A-3) was 7,800, and the glass transition point thereof was 46 ° C.

Instead of the copolymers (A-1) and (B-1) used in Example 1, 10 g of the copolymer (A-3) (as solid content)
And the same procedure as in Example 1 except that 30 g (as a solid content) of the copolymer (B-1) of Synthesis Example (3) was used to produce a photoconductor. It was measured. The smoothness of the photoconductive layer surface of the photoreceptor was 80 (sec / cc), which was smooth. V ₁₀ ; -550V, DRR; 96%, E _1/10 3.5 (1μx.sec)
In addition, the image quality was good even in the image pickup under the environment of (30 ° C, 80% RH).

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.

Further, after making a plate in the same manner as in Example 1 and printing as an offset master original plate or printing 10,000 sheets, a printed matter with clear image quality without generation of scumming was obtained.

Examples 3 to 6 Copolymers were 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.

Instead of the copolymers (A-1) and (B-1) used in Example 1, 10 g of each of the copolymers A-4 to A-7 (as solid content) and the copolymer weight produced in Synthesis Example 3 were used. 30g of combined (B-1)
Each photoreceptor was manufactured in the same manner as in Example 1 except that (as the solid content) was used, and each property was measured in the same manner as in Example 1.

All of the light-sensitive materials of the present invention have excellent chargeability, dark charge retention rate, and photosensitivity, and the actual copied images have high temperature and high humidity (30 ° C, 80% R
Even under the harsh conditions of H), a clear image with no background fog or fine line skipping was provided. 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.

Examples 7 to 12 As the resin [B] of the present invention, copolymers shown in Table 3 were synthesized.

Resin [A] in Table-2 and resin [B] in Table-3 (1/3)
Each light-sensitive material was prepared in the same manner as in Example 1, except that the weight ratios shown in Table 4 were used. Further Example 1
The electrostatic characteristics were measured in the same manner as in. The results are shown in Table-4.
I wrote it in.

All of the light-sensitive materials of the present invention have excellent chargeability, dark charge retention rate, and photosensitivity, and the actual copied images have high temperature and high humidity (30 ° C, 80% R
Even under the harsh conditions of H), a clear image with no background fog or fine line skipping was provided.

Further, after making a plate in the same manner as in Example 1 and printing as an offset master original plate or printing 10,000 sheets, a printed matter with clear image quality without generation of scumming was obtained.

Example 13 A mixed solution of 95 g of benzyl methacrylate and 200 g of jumped 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 (A-8) was 8,500 and the glass transition point thereof was 38 ° C.

A photosensitive material was prepared in the same manner as in Example 2 except that 10 g of the copolymer (A-8) was used in place of the copolymer [A-3]. 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.

Further, after making a plate in the same manner as in Example 1 and printing as an offset master original plate or printing 10,000 sheets, a printed matter with clear image quality without generation of scumming was obtained.

Example 14 A mixed solution of 94 g of n-propyl methacrylate, 6 g of 2-aminoethanethiol, 100 g of isopropyl alcohol and 200 g of tetrahydrofuran was heated to a temperature of 75 ° C. under a stream of nitrogen, and then 1.0 g of azobisisobutyronitrile was added thereto. Reacted for hours. After cooling, the product was reprecipitated in 2 l of water to precipitate the reaction product, the solvent was decanted, and then the product was dried under reduced pressure at a temperature of 40 ° C.

The obtained copolymer was dissolved in 200 g of toluene and the temperature was adjusted to 90 ° C., 1.3 g of maleic anhydride and 1 g of pyridine were added, and the mixture was stirred for 10 hours for reaction. The weight average molecular weight of the obtained copolymer (A-9) was 6,200, and the glass transition point thereof was 35 ° C.

Instead of the copolymers (A-1) and (B-1) used in Example 1, 10 g of the copolymer (A-9) (as solid content).
And the same procedure as in Example 1 except that 30 g (as solid content) of the copolymer (B-1) of Synthesis Example (3) was used to produce each photoconductor, and each characteristic was obtained in the same manner as in Example 1. Was measured.

Example 15 and Comparative Example D 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.
V 1g was added and reacted for 8 hours.

The weight average molecular weight of the obtained copolymer (A-10) was 8,300.
The glass transition point was 43 ° C. Thus obtained copolymer 8g (as solid content), copolymer (B-1) 32g of Synthesis Example (3), zinc oxide 200g, heptamethine cyanine dye 0.02g represented by the following structural formula, Phthalic anhydride 0.0
A mixture of 5 g and 300 g of toluene was 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 15). On the other hand, 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 was heated to a temperature of 100 ° C. under a nitrogen stream, then 6.0 g of azobisisobutyronitrile was added, and reacted for 8 hours. Let
The weight average molecular weight of the copolymer thus obtained was 8,
The glass transition point was 000. Using this resin instead of the copolymer (A-10) in Example (15),
Photoreceptor D was produced in the same manner as in Example 10 (Comparative Example D).

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
780 nm) was used. The results are shown in Table-5.

The DRR of Comparative Example D is worse than that of Comparative Example C. 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.

(Effects of the Invention) According to the present invention, an electrophotographic light-sensitive 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 at least one of the resins [B]. An electrophotographic photosensitive member comprising one kind. (I) Resin [A]; having a weight average molecular weight of 10 ^{3 to} 3 × 10 ⁴ , and -PO ₃ H
_A resin obtained by bonding at least one acidic group selected from _two groups, a —SO ₃ H group and a —COOH group only to the end of the polymer main chain (ii) Resin [B]; 10 ^{4 to} 5 × 10 has a weight average molecular weight of ^5, and has a pKa greater than pKa of the acid groups contained in the resin (a) used in _{combination, -PO 3 H 2, -SO 3} H, -COOH and (R represents a hydrocarbon group) A resin containing a copolymerization component containing at least one acidic group selected from