JPH06289629A - Electrophotographic photoreceptor - Google Patents

Abstract

PURPOSE:To provide an electrophotographic photoreceptor high in sensitivity, small in residual potential and excellent in repeatability property and adhesivity at the time of repeatingly using in electrophotographic process. CONSTITUTION:In the electrophotographic photoreceptor provided with a photosensitive layer made by laminating a charge generating layer and a charge transfer layer on a conductive supporting body, a binding resin for charge generating layer contains a compound having epoxy group and a polyvinylbutylal resin and a binding resin for charge transfer layer contains a polycarbonate resin, plyallylate resin and a polyester resin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photoconductor, and more particularly to an electrophotographic photoconductor having high sensitivity and excellent repeatability and adhesiveness.

[0002]

2. Description of the Related Art Conventionally, as an electrophotographic photosensitive member,
Those having a photosensitive layer containing an inorganic photoconductor as a main component such as selenium, cadmium sulfide, zinc oxide, and silicon have been widely known. However, they are sensitive, heat stable, moisture resistant,
Durability and the like are not always satisfactory, and particularly selenium and cadmium sulfide are restricted in production and handling due to their toxicity.

On the other hand, an electrophotographic photosensitive member having a photosensitive layer containing an organic photoconductive compound as a main component is relatively easy to manufacture, inexpensive, easy to handle, and generally selenium photosensitive. It has many advantages such as superior thermal stability to the body, and has received much attention in recent years.

As such an organic photoconductive compound,
Poly-N-vinylcarbazole is well known, and an electrophotographic photosensitive material having a photosensitive layer containing as a main component a charge transfer complex formed from this and a Lewis acid such as 2,4,7-trinitro-9-fluorenone. The body is special Japanese Sho 50-10496
It is described in Japanese Patent Publication No. However, this photoreceptor was not always satisfactory in sensitivity, film-forming property and durability.

On the other hand, an electrophotographic photosensitive material containing a low molecular weight organic photoconductive compound in which a charge transfer agent typified by triphenylamines, stilbenes and hydrazones and a charge generating agent such as phthalocyanine and an azo pigment are combined. The body is proposed. By combining these with an appropriate binder, and further combining a compound having a high charge generation ability and a compound having a high charge transfer ability, for example, as a layered type photoreceptor, a compound having a sensitivity close to that of an inorganic photoreceptor such as selenium has appeared. There is. As a result, in the field of copying machines, printers, etc., photoconductors containing such an organic photoconductive compound as a main component have made great progress.

The laminated or dispersed function-separated type photoconductor in which the charge generation function and the charge transfer function are shared by different substances has a wide selection range of each material, and the charging characteristics, sensitivity and durability are large. It has an advantage that an electrophotographic photosensitive member having arbitrary characteristics in terms of electrophotographic characteristics can be prepared relatively easily.

Conventionally, various types of charge generating agents or charge transfer agents have been proposed. For example, an electrophotographic photoreceptor having a photosensitive layer in which a charge generation layer made of amorphous selenium and a charge transfer layer containing poly-N-vinylcarbazole as a main component are combined has been put into practical use. However, the charge generation layer made of amorphous selenium has a drawback of poor durability. Further, various proposals have been made to use an organic dye or pigment as a charge generating agent. For example, as an electrophotographic photoreceptor containing a monoazo pigment or a bisazo pigment in a photosensitive layer, JP-B-48-30513, Kaisho 52
No. 4241, Japanese Patent Application Laid-Open No. 54-46558, Japanese Patent Publication No. 56-11945 and the like are already known.

However, there are very few practically used function-separated type photoreceptors, and many required characteristics such as charging characteristics, sensitivity, residual potential, pre-exposure characteristics, and repetitive use characteristics. It is difficult to say that we are satisfied with everything. It can be said that these properties largely depend on the performance of each of the charge generating agent and the charge transfer agent, but it is also known that the selection of a suitable combination thereof is important, and many proposals have been made.
The reason is considered to be that such selection is not based on a theoretical basis but is made by trial and error.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic photosensitive member which has high sensitivity, has a small residual potential, and has excellent adhesiveness and stability upon repeated use in an electrophotographic process. Especially.

[0010]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventor has found that a compound having an epoxy group and a polyvinyl butyral resin are used as a binder resin for a charge generation layer in an electrophotographic photoreceptor. The present invention has been found out that it is effective to include a polycarbonate resin, a polyarylate resin and a polyester resin as a binder resin for the charge transfer layer.

Examples of the compound having an epoxy group used as the binder resin of the charge generation layer in the present invention include, but are not limited to, the following.

[0012]

[Chemical 1]

[0013]

[Chemical 2]

R ₁ and R ₂ represent an alkyl group.

[0015]

[Chemical 3]

A represents an integer of 1 or more and 20 or less.

[0017]

[Chemical 4]

[0018]

[Chemical 5]

B represents an integer of 1 or more and 20 or less.

[0020]

[Chemical 6]

C and d are integers of 1 or more and 20 or less.

[0022]

[Chemical 7]

E and f are integers of 1 or more and 20 or less.

[0024]

[Chemical 8]

[0025]

[Chemical 9]

G represents an integer of 1 or more and 20 or less.

[0027]

[Chemical 10]

H represents an integer of 0 or more and 20 or less.

[0029]

[Chemical 11]

I represents an integer of 0 or more and 20 or less, and X represents halogen atoms which may be different from each other.

[0031]

[Chemical 12]

[0032]

[Chemical 13]

[0033]

[Chemical 14]

[0034]

[Chemical 15]

J represents an integer of 1 or more and 20 or less.

[0036]

[Chemical 16]

[0037]

[Chemical 17]

[0038]

[Chemical 18]

K is an integer of 0 or more and 20 or less, and R ₃ and R ₄ are hydrogen atoms or alkyl groups.

Further, a polymer compound having an epoxy group as shown below can be used, but is not limited thereto.

[0041]

[Chemical 19]

[0042]

[Chemical 20]

[0043]

[Chemical 21]

[0044]

[Chemical formula 22]

[0045]

[Chemical formula 23]

Here, l, m, n, o, p, q, r,
s, t, u, v, w, x and y represent the number (integer) of each monomer constituting the polymer compound, and 0 <l + m ≦ 100.
0, 0 <n + o + p ≦ 1000, 0 <q + r + s ≦ 10
00, 0 <t + u + v ≦ 1000, 0 <w + x + y ≦ 1
It is 000.

The compounds having an epoxy group described above include Araldite resin manufactured by Ciba-Geigy Co., Ltd., Epicoat resin manufactured by Yuka Shell Epoxy Co., Ltd., Rikaresin resin manufactured by Shin Nippon Rika Co., Ltd., and Epitote manufactured by Toto Kasei Co., Ltd. Examples thereof include resins, but are not limited thereto.

Among the above-mentioned compounds having an epoxy group, compounds represented by the following general formulas (I) and (II) are preferable, such as chemical formula 6, chemical formula 7, chemical formula 12, chemical formula 16, chemical formula 18, chemical formula 20, and the like. Is particularly preferable.

[0049]

[Chemical formula 24]

In the formula, R ₅ represents a hydrogen atom or an alkyl group, and A and B represent an integer of 1 or more and 20 or less.

[0051]

[Chemical 25]

In the formula, C + D represents an integer of 1 or more and 20 or less.

The polyvinyl butyral resin used as the binder resin of the charge generation layer in the present invention includes, but is not limited to, those represented by the following general formula (III).

[0054]

[Chemical formula 26]

In the formula, E is an integer from 1 to 5000, and E +
F + G represents an integer of 1 or more and 5000 or less, and E is E + F
Equal to or less than + G. Where E / (E +
F + G) represents the degree of butyralization and is preferably 0.5 or more and 0.9 or less.

Examples of the polycarbonate resin used as the binder resin of the charge transfer layer in the present invention include, but are not limited to, the following. Here, N represents an integer of 10 or more and 1000 or less.

[0057]

[Chemical 27]

[0058]

[Chemical 28]

[0059]

[Chemical 29]

[0060]

[Chemical 30]

[0061]

[Chemical 31]

[0062]

[Chemical 32]

[0063]

[Chemical 33]

[0064]

[Chemical 34]

[0065]

[Chemical 35]

[0066]

[Chemical 36]

Examples of the polyarylate resin used as the binder resin of the charge transfer layer in the present invention include, but are not limited to, those represented by the following general formula (IV). Here, M represents an integer of 10 or more and 1000 or less.

[0068]

[Chemical 37]

The polyarylate resin represented by the chemical formula 37 is
Examples include U-polymer resins manufactured by Unitika Ltd., but are not limited thereto.

As the polyester resin used as the binder resin of the charge transfer layer in the present invention, Toyobo
Examples thereof include Vylon resin manufactured by Co., Ltd., but are not limited thereto.

Hereinafter, each component of the present invention will be described in detail.

First, as the electroconductive support on which the photosensitive layer of the photoconductor is formed, any of those known in electrophotographic photoconductors can be used. Specifically, for example, gold,
Silver, platinum, titanium, aluminum, copper, zinc, iron,
Examples thereof include a drum, a sheet, a belt made of a metal oxide or the like that has been subjected to a conductive treatment, a laminate of these thin films, and a vapor deposition product.

Further, metal powder, metal oxide, carbon black, carbon fiber, copper iodide, charge transfer complex, inorganic salt,
Examples thereof include drums, sheets, belts and the like, which are made of plastic, ceramic, paper or the like, which is coated with a conductive substance such as an ion conductive polymer electrolyte together with a suitable binder and embedded in a polymer matrix to be subjected to a conductive treatment.

The charge generating layer is applied by dispersing the pigment or dye as a charge generating agent together with the compound having an epoxy group and the polyvinyl butyral resin, or if necessary, by mixing with other resin as a binder, and dispersing in a solvent. It can be provided.

As the other binder resin for the charge generating layer which can be used together with the epoxy group-containing compound and the polyvinyl butyral resin, there are conventionally known polymers of vinyl compounds such as styrene, vinyl acetate and acrylic acid ester. And copolymers, phenoxy resins, formal resins, urethane resins, phenol resins, polycarbonate resins, polyester resins, polyarylate resins and the like, but are not limited thereto.

The charge generating agent used is an azo pigment represented by a monoazo pigment, a polyazo pigment, a metal complex salt azo pigment, a stilbene pigment and a thiazole azo pigment.
Perylene pigments typified by perylene anhydrides and perylene imides, anthraquinone derivatives, anthanthrone derivatives, dibenzpyrenequinone derivatives, pyranthrone derivatives, violanthrone derivatives, and anthraquinone derivatives such as isoviolanthrone derivatives. Cyclic quinone pigments, phthalocyanine pigments such as metal phthalocyanines, metal-free phthalocyanines, metal naphthalocyanines and metal-free naphthalocyanines, triphenylmethane dyes such as methyl violet, and quinoline pigments such as quinizarin. Examples thereof include pyrylium salt dyes represented by dyes, thiapyrylium salts and benzopyrylium salts.

Among these, bisazo pigments, trisazo pigments, and phthalocyanine pigments having high carrier generation efficiency are preferable because they give high sensitivity and provide an excellent photoconductor. For example, in the case of a bisazo pigment, JP-A Nos. 62-286058, 63-32557, 63-243948, 64-21453, 64-21455 and 64-21455. -94350 and 1-20026.
The compounds described in JP-A No. 7 and JP-A No. 1-220757 can be used.

The binder resin for the charge generating layer containing both the compound having an epoxy group and the polyvinyl butyral resin is 0.1 to 1 with respect to 100 parts by weight of the charge generating agent.
It is used in an amount of 000 parts by weight, preferably 1 to 400 parts by weight. In addition, the polyvinyl butyral resin is 1 to 20 parts by weight with respect to 100 parts by weight of the compound having an epoxy group.
Used in the range of 0 parts by weight. The thickness of the charge generation layer is 0.
It is used in the range of 05 to 20 μm, preferably 0.1 to 2 μm.

Examples of the solvent used include ethers such as 1,2-dimethoxyethane, tetrahydrofuran and 1,4-dioxane, ketones such as methyl ethyl ketone and cyclohexanone, aromatic hydrocarbons such as toluene and xylene, and N, N-. Dimethylformamide, acetonitrile,
Aprotic polar solvents such as N-methylpyrrolidone and dimethyl sulfoxide, alcohols such as methanol, ethanol and isopropanol, methyl acetate, ethyl acetate,
Examples thereof include esters such as methyl cellosolve acetate and halogenated hydrocarbons such as dichloroethane and chloroform.

The charge transfer layer can be provided by adding the charge transfer agent and the above-mentioned polycarbonate resin, polyarylate resin and polyester resin or, if necessary, other binder resin, dissolving in a suitable solvent and coating.

Other binder resins used in combination with the above-mentioned polycarbonate resin, polyarylate resin and polyester resin include polymers and copolymers of vinyl compounds such as styrene, vinyl chloride, vinyl acetate, acrylic acid ester, and methacrylic acid ester. , Phenoxy resin,
Examples include various polymers such as polysulfone, cellulose ester resin, cellulose ether resin, urethane resin, epoxy resin, and silicone resin.

Examples of the solvent used include tetrahydrofuran, methyl ethyl ketone, benzene, toluene, monochlorobenzene, 1,2-dichloroethane, dichloromethane, chloroform, ethyl acetate and the like.

The charge transfer agent used in the charge transfer layer includes a hole transfer agent and an electron transfer agent. Examples of the former include oxadiazoles disclosed in JP-B-34-5466, triphenylmethanes disclosed in JP-B-45-555, and JP-B-52-4188. Pyrazolines, hydrazones disclosed in JP-B-55-42380, and JP-A-56-123.
The oxadiazoles disclosed in Japanese Patent No. 544, the triarylamines disclosed in Japanese Patent Publication No. 58-32372, the stilbenes disclosed in Japanese Patent Publication No. 58-198043, and the like can be mentioned. it can. On the other hand, examples of the electron transfer agent include chloranil, tetracyanoethylene, 2,4,7-trinitro-9-fluorenone,
2,4,5,7-tetranitroxanthone, 1,3,7
-Trinitrodibenzothiophene and the like. These charge transfer agents can be used alone or in combination of two or more.

Among these charge transfer agents, hydrazone compounds and stilbene compounds are preferable because they have high charge (hole) mobility and provide an excellent photoconductor. For example, in the case of a hydrazone compound, the above-mentioned Japanese Patent Publication No. 55-4
2380, and Japanese Patent Laid-Open No. 1-10055
No. 5, gazette No. 2-10367 gazette, and No. 2-511163.
JP-A No. 2-96767 and JP-A No. 2-183260.
No. 2, 184856 and No. 2-18485.
No. 8, No. 2-184859, No. 2-2261
The hydrazone compounds described in JP-A-60, etc. can be used.

The binder resin for the charge transfer layer containing the above-mentioned polycarbonate resin, polyarylate resin and polyester resin is 20 to 5 per 100 parts by weight of the charge transfer agent.
It is used in an amount of 00 parts by weight, preferably 50 to 200 parts by weight. Further, the polyarylate resin is used in the range of 20 to 300 parts by weight, and the polyester resin is used in the range of 20 to 200 parts by weight with respect to 100 parts by weight of the polycarbonate resin. The thickness of the charge transfer layer is used in the range of 1 to 100 μm, preferably 10 to 50 μm.

A blocking layer may be provided between the photosensitive layer and the conductive support in order to control charge injection from the photosensitive layer to the conductive support. A surface layer may be provided in order to improve.

The photosensitive layer may contain a well-known plasticizer in order to improve film-forming property, flexibility and mechanical strength. Examples of the plasticizer include phthalic acid esters, phosphoric acid esters, chlorinated paraffins, chlorinated fatty acid esters, aromatic compounds such as methylnaphthalene, and the like.

Furthermore, in order to improve the electrophotographic characteristics of the photoconductor, an additive such as an antioxidant may be contained.

[0089]

EXAMPLES The present invention will now be described in more detail by way of examples, which should not be construed as limiting the invention thereto.

Example 1

[0091]

[Chemical 38]

1 part by weight of the bisazo pigment represented by the above formula 38, 0.8 part by weight of a compound having an epoxy group (Rikaresin HBE manufactured by Shin Nippon Rika Co., Ltd.) and polyvinyl butyral resin (Denka Butyral manufactured by Denki Kagaku Co., Ltd.) # 3000-
1) 0.2 parts by weight of 1,2-dimethoxyethane 100
The mixture was mixed with 1 part by weight and dispersed for 4 hours together with glass beads using a paint conditioner. The pigment dispersion thus obtained was coated on an aluminum vapor-deposited film (Metal Me manufactured by Toray Industries, Inc.) with an applicator and dried at 80 ° C. for 15 minutes to obtain a charge generation layer having a thickness of about 0.2 μm.

[0093]

[Chemical Formula 39]

Next, 10 parts by weight of the hydrazone compound represented by the above formula 39 and the polycarbonate resin represented by the above formula 28 (Panlite K-130 manufactured by Mitsubishi Gas Chemical Co., Inc.) are used.
0) 4 parts by weight, 4 parts by weight of polyarylate resin (U-100 manufactured by Unitika Ltd.) represented by the above general formula 37 and 2 parts by weight of polyester resin (Byron 290 manufactured by Toyobo Co., Ltd.) in 200 parts by weight of dichloromethane. Dissolve and apply this solution on the charge generation layer with an applicator.
It was dried at 0 ° C. for 60 minutes to form a charge transfer layer having a dry film thickness of 20 μm.

The laminated electrophotographic photosensitive member thus produced was allowed to stand still overnight at room temperature in a dark place, and then electrophotographic characteristics were evaluated by an electrostatic recording tester (SP-428 manufactured by Kawaguchi Electric Co., Ltd.). . The measurement conditions are: corona applied voltage: -5 kV,
Static mode No. 3 (Process speed 167 mm
/ Sec), illumination light (white light) illuminance: 2lux. As a result, the charging potential was −720 V and the half exposure was 1.2 lux.
・ It showed a very high sensitivity value of seconds.

Next, this photosensitive member was attached to an aluminum drum base tube, and the repeating characteristics of charging and photo-erasing were evaluated by a drum photosensitive member evaluation device (Cynthia 90 manufactured by Gentec Co., Ltd.). Measured corona applied voltage: -5.2k
V, process speed 160 mm / sec, and 5000 times of charging and photo-erasing in TCCD2 mode were repeated. Photostatic elimination was performed using a tungsten lamp array. Table 1 shows the measurement results of the surface potential after charging, that is, the charging potential, and the surface potential after photo-eliminating, that is, the residual potential. It can be seen that the changes in charging potential and residual potential are extremely small.

Further, in order to measure the adhesiveness of the photoconductor prepared in the same manner as described above, CROSSCUT GUIDE
Using 1.0 (manufactured by Co-Tech Co., Ltd.), make 11 cuts with a cutter knife so as to cross the photoconductor vertically and horizontally, and make 100 crevices, then use scotch tape (manufactured by Nichiban Co., Ltd.) A peel test was performed. At this time, the number of cells left without peeling was used as a measure of adhesiveness. The results are shown in Table 1.

[0098]

[Table 1]

Examples 2 to 10 A combination of a compound having an epoxy group which is a binder resin for a charge generating layer and a polyvinyl butyral resin is used as an exemplified compound shown in Tables 2 and 3 below, and a polycarbonate resin which is a binder resin for a charge transfer layer. Tables 4 and 5 below show combinations of the polyarylate resin and the polyester resin.
A photoconductor was prepared in the same manner as in Example 1 except that the exemplified compound shown in 1 above was used, and the electrophotographic characteristics, the repeating characteristics of charging and light elimination, and the adhesiveness were measured. The results are shown in Table 6.

[0100]

[Table 2]

[0101]

[Table 3]

[0102]

[Table 4]

[0103]

[Table 5]

[0104]

[Table 6]

Comparative Examples 1 to 4 The resins shown in Table 7 were used as the binder resin for the charge generation layer, and Table 8 was used as the binder resin for the charge transfer layer.
A photoconductor was prepared in the same manner as in Example 1 except that the resin described in 1 above was used, and the electrophotographic characteristics, the repeating characteristics of charging and light elimination, and the adhesiveness were measured. The results are shown in Table 9.

[0106]

[Table 7]

[0107]

[Table 8]

[0108]

[Table 9]

Examples 11 to 20

[0110]

[Chemical 40]

[0111]

[Chemical 41]

The bisazo pigment represented by the above formula 40 is used as the charge generating agent, the hydrazone compound represented by the above formula 41 is used as the charge transfer agent, and a compound having an epoxy group which is a binder resin for the charge generating layer and polyvinyl are used. The combinations of butyral resins are exemplified compounds shown in Tables 10 and 11 below, and the combinations of polycarbonate resins, polyarylate resins and polyester resins, which are binder resins for charge transfer layers, are shown in Tables 12 and 13 below and the amounts thereof used. A photoconductor was prepared in the same manner as in Example 1 except that the above was used, and the electrophotographic characteristics, the repeating characteristics of charging and light elimination, and the adhesiveness were measured. The results are shown in Table 14.
Shown in.

[0113]

[Table 10]

[0114]

[Table 11]

[0115]

[Table 12]

[0116]

[Table 13]

[0117]

[Table 14]

Comparative Examples 5 to 8 The same procedure as in Examples 11 to 20 except that the charge generating layer binder resin was the exemplified compound shown in Table 15 below and the charge transfer layer binder resin was the exemplified compound shown in Table 16 below. A photoconductor was prepared by using the same, and the electrophotographic characteristics, the repeating characteristics of charging and light elimination, and the adhesiveness were measured. The results are shown in Table 17.

[0119]

[Table 15]

[0120]

[Table 16]

[0121]

[Table 17]

Examples 21 to 30

[0123]

[Chemical 42]

[0124]

[Chemical 43]

The bisazo pigment represented by the above formula 42 is used as the charge generating agent, the hydrazone compound represented by the above formula 43 is used as the charge transfer agent, and a compound having an epoxy group as a binder resin for the charge generating layer and polyvinyl are used. The combinations of butyral resins are exemplified compounds shown in Tables 18 and 19 below, and the combinations of polycarbonate resins, polyarylate resins and polyester resins, which are binder resins for the charge transfer layer, are shown in Tables 20 and 21 below and the amounts used. A photoconductor was prepared in the same manner as in Example 1 except that the above was used, and the electrophotographic characteristics, the repeating characteristics of charging and light elimination, and the adhesiveness were measured. The results are shown in Table 22.
Shown in.

[0126]

[Table 18]

[0127]

[Table 19]

[0128]

[Table 20]

[0129]

[Table 21]

[0130]

[Table 22]

Comparative Examples 9 to 12 In Examples 21 to 30, as the binder resin for the charge generation layer, the exemplified compounds shown in Tables 23 and 24 below were used, and as the binder resin for the charge transfer layer, Tables 25 and 26 below.
A photoconductor was prepared in the same manner except that the exemplified compound shown in 1 was used, and electrophotographic properties, repetitive properties of charging and light neutralization, and adhesive properties were measured. The results are shown in Table 27.

[0132]

[Table 23]

[0133]

[Table 24]

[0134]

[Table 25]

[0135]

[Table 26]

[0136]

[Table 27]

From these results, it can be seen that the photoreceptors of the present invention shown in Examples are superior in adhesiveness and electrophotographic characteristics, particularly in stability of charging potential and residual potential due to repeated use, as compared with Comparative Examples.

[0138]

As is apparent from the above, according to the present invention, it is possible to provide an electrophotographic photoreceptor having high sensitivity, small residual potential, and excellent repeating characteristics and adhesiveness.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hideya Arisue 34-2, Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Paper Mills, Ltd.

Claims (1)

[Claims] 1. An electrophotographic photoreceptor comprising a photosensitive layer comprising a charge generation layer containing at least a charge generation agent and a charge transfer layer containing a charge transfer agent, which is laminated on a conductive support. Contains a compound having an epoxy group as a binder resin and a polyvinyl butyral resin,
Further, the charge transfer layer contains a polycarbonate resin, a polyarylate resin and a polyester resin as a binder resin, the electrophotographic photoreceptor.