JPS63139357A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To prevent the rise of residual potential at the time of low humidity by incorporating a dye having a sodium sulfonate group in an interlayer formed between an electric conductive substrate and a photosensitive layer. CONSTITUTION:The electrophotographic sensitive body is provided with the interlayer containing the dye having the sodium sulfonate group between the electric conductive substrate and the photosensitive layer to adapt to repeated uses. The addition of such a dye to the interlayer permits the rise of residual potential to be effectively suppressed and good repeating characteristic to be given. The dye to be added to the interlayer is such as Direct Violet 1, Direct Yellow 8, and Direct Red 39, represented by formula I, II and III, respectively. It is preferred to prepare the interlayer by coating the electric conductive substrate with a solution containing the dye and a binder and drying it.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an electrophotographic photoreceptor, and more particularly, to improvement of an intermediate layer in an electrophotographic photoreceptor repeatedly used in PPC copiers, laser beam printers, digital copiers, etc. .

[Prior Art] In general, electrophotographic photoreceptors that are used repeatedly (hereinafter sometimes simply referred to as "photoreceptors") must have good charging properties (by preventing unnecessary charge injection and An intermediate layer made of a resin with relatively low resistance is provided between the substrate and the photosensitive layer in order to maintain charge acceptance) and to ensure good adhesion of the photosensitive layer to the substrate. .

Conventionally, as resins for the intermediate layer, (a) water-soluble resins such as casein and polyvinyl alcohol, (b) polyamide resins such as nylon and copolymerized nylon, and (C) photo- or thermosetting resins have been used. In a photoreceptor having an intermediate layer formed thereon, the intermediate layer has a high resistance at low humidity, resulting in an increase in residual potential, and as a result, there is a tendency for the repeatability to decrease.

As a means to eliminate these disadvantages, it is possible to add conductive pigments such as indium oxide, tin oxide, carbon, etc. to the intermediate layer (Japanese Unexamined Patent Publication No. 58-93063) or to add a conductive polymer (Japanese Unexamined Patent Publication No. 58-93063). -95744
Publication No. 2), etc. have been proposed. However, in the former case, the charging property decreases, so a second intermediate layer consisting only of resin must be formed between the conductive pigment-containing intermediate layer and the photosensitive layer, and in the latter case, the charging property decreases. Although the performance does not deteriorate, a decrease in sensitivity is observed, which poses a practical problem.

[Objective] An object of the present invention is to provide an electrophotographic photoreceptor that eliminates humidity dependence (residual potential increase at low humidity) without affecting the photoreceptor characteristics and is further suitable for repeated use. be.

[Constitution] The present invention provides an electrophotographic photoreceptor that has an intermediate layer between a conductive substrate and a photosensitive layer and is used repeatedly, wherein the intermediate layer contains a dye having a sodium sulfonate group. It is characterized by

Incidentally, the present inventors have found that when a dye having a sodium sulfonate group is added to the intermediate layer, the increase in residual potential in a low-humidity environment can be effectively suppressed, and the photoreceptor thus obtained is good. It was confirmed that it also has excellent repeatability characteristics. The present invention has been made based on this knowledge.

The present invention will be explained in more detail below. As mentioned above, the photoreceptor of the present invention has a structure in which an intermediate layer and a photosensitive layer are sequentially laminated on a conductive substrate. Conductive substrates include metals such as aluminum, nickel, and stainless steel; plastics in which conductive pigments such as carbon are dispersed; metals deposited on insulating supports (such as plastics or plastic films) or coated with conductive paints. An example is something that has been modified.

The dye contained in the intermediate layer has a sodium sulfonate group, and examples of such dyes include the following.

C,H.

(Direct Yellow 8) 03Na (Direct Let 39) (Direct Violet 1) The intermediate layer used in the present invention contains a liquid containing a dye and a binder.
It is preferable to apply it on a conductive support and dry it. Examples of the binder used here include polyvinyl alcohol, sodium polyacrylate, carboxymethylcellulose-sodium sinate, copolymerized nylon, and alkoxymethylated nylon. The blending ratio of this binder and the dye is 1.00 parts by weight of the binder and 0.00 parts by weight of the dye.
A suitable amount is 1 to 50 parts by weight, preferably 1 to 30 parts by weight.

Further, the intermediate layer may contain an inorganic pigment if necessary. Examples of these inorganic pigments include titanium dioxide, zinc white, zinc sulfide, lead white, tin carbon, charcoal, alumina, barium sulfate, and white carbon. When an inorganic pigment is included, the binder, dye, inorganic pigment, and solvent are placed in a ball mill or the like, the pigment is well dispersed, and the resulting dispersion is applied onto a conductive support and dried.

The blending ratio of inorganic pigment and binder varies depending on the materials used, so it cannot be set uniformly, but when 1 part by weight of binder is used, the amount of inorganic pigment is 0.

It is preferably about 0.05 to 10 parts by weight.

The photosensitive layer is (1) a charge transfer complex formed by a combination of an electron-donating compound and an electron-accepting compound (USP 3).
484237), (2) organic photoconductors sensitized by adding dyes (described in Japanese Patent Publication No. 4G-25658), (3) pigments dispersed in a hole- or electron-active matrix ( (described in publications such as JP-A-47-30328 and JP-A-47-18545).

(4) Functionally separated charge generation layer and charge transport layer (
(described in JP-A No. 49-105537), (5) those whose main component is a eutectic complex consisting of a dye and a resin (described in JP-A-47-10785), (6) in a charge transfer complex. It may be formed of any conventionally known organic photoconductor, such as one to which an organic pigment or an inorganic charge-generating material is added (described in Japanese Patent Application Laid-Open No. 49-91648).

However, among these, the laminated photoreceptor of type (4) is particularly advantageous because materials can be selected from a variety of materials depending on the function.

The charge-generating layer is made of polyester, charge-generating substances such as azo pigments, phthalocyanine pigments, square pigments, indigo pigments, perylene pigments, selenium powder, selenium alloy powder, amorphous silicon powder, zinc oxide powder, and cadmium sulfide powder. It is formed by dispersing in a solution of a binder resin such as polycarbonate, polyvinyl butyral, or acrylic resin, and coating this on the intermediate layer. 1
! The appropriate thickness of the load-generating layer is about 0.01 to 2 μm.

The charge transport layer is an α-phenylstilbene compound (Japanese Patent Application Laid-open No.
8-198043), hydrazone compounds (
A charge transporting substance such as those described in JP-A No. 55-46760 is dissolved in a film-forming resin such as polyester, polysulfone, polycarbonate, polymethacrylic acid ester, polystyrene, etc., and this is applied onto the charge generation layer. It is sufficient to coat the film to a thickness of about 10 to 30 μm. The reason why a film-forming resin is used here is that charge transporting substances generally have a low molecular weight and are poor in film-forming properties by themselves.

The photoreceptor thus manufactured is suitable for repeated use, and if necessary, a protective layer similar to conventional methods can be provided on the surface of the photoreceptor layer.

Next, examples and comparative examples will be shown.

Example 1 Alcohol-soluble copolymerized nylon (CM-80 manufactured by Toshi Co., Ltd.)
00) was dissolved in 100 g of methanol, and dilate yellow 11 (manufactured by Tokyo Kasei Kogyo Co., Ltd., Sun
Yellow) 1 g and 6 g of titanium oxide powder (Tiebake R-680, manufactured by Ishihara Sangyo Co., Ltd.) were added and dispersed in a ball mill for 12 hours. The resulting coating solution was dip-coated onto the surface of an aluminum plate (manufactured by Sumitomo Light Metal Co., Ltd.) with a thickness of 0.2 mm, and dried at 120° C. for 10 minutes. The thickness of the intermediate layer thus obtained is approximately 4 μm.
Met.

Next, butyral resin (S-LEC BL- manufactured by Suizui Kagaku Co., Ltd.)
5) Dissolve 5 g in cyclohexanone 150.

Trisazo pigment Log having the following structural formula (If) was added to this and dispersed in a ball mill for 48 hours, and further 210 g of cyclohexanone was added and dispersed for 3 hours. Take this out into a container, and the solid content is 1.
It was diluted with cyclohexanone while stirring to a concentration of 5%. The charge generation layer coating solution thus obtained was dip coated onto the intermediate layer and dried at 120° C. for 10 minutes.

The thickness of the charge generation layer thus obtained was approximately 0.3μ.
It was m.

In addition, polycarbonate resin (for Panlight manufactured by Densha Co., Ltd.)
1300) was dissolved in 90 g of tetrahydrofuran, and 7 g of a charge transport substance having the following structural formula (III) was dissolved therein. The charge transport layer coating solution thus obtained is dip coated onto the charge generation layer and dried at 120°C for 30 minutes to form a charge transport layer with a thickness of about 20 μm. Inventive product 1) was created.

Comparative Example 1 A comparative electrophotographic photoreceptor (comparative product 1) was prepared in exactly the same manner as in Example 1 except that Direct Yellow 11 (Sun Yellow) was omitted.

Example 2 Alcohol-soluble copolymerized nylon (CM-40 manufactured by Toshi Co., Ltd.)
0) log was dissolved in 90 g of methanol, and Ac1d Red 52 (Aizen Ac1d R
2.0 g of hodamine BH (manufactured by Hodo Kagaku Co., Ltd.) and titanium oxide powder (Tiebake R-680, manufactured by Ishihara Sangyo Co., Ltd.)
) 6 g was added, and dispersion was carried out in a ball mill for 12 hours. The obtained coating solution was dip-coated onto the surface of a 0.2 m thick aluminum plate (manufactured by Jumen Light Metal Co., Ltd.) for 12 min.
Drying was performed at 0°C for 10 minutes. The thickness of the intermediate layer thus obtained was approximately 4 μI.

Next, polyester resin (Byron 200 manufactured by Toyobo Co., Ltd.
) was dissolved in 150 g of cyclohexanone, 10 g of a bisazo pigment having the following structural formula (V) was added thereto, and the mixture was dispersed in a ball mill for 48 hours. Take this into a container and the solid content is 1.0
% with cyclohexanone while stirring. The charge generation layer coating solution thus obtained was dip coated onto the intermediate layer and dried at 130° C. for 10 minutes. The thickness of the charge generation layer thus obtained was approximately 0.
It was 3 μm.

Further, 12 g of polycarbonate resin (Panlite-1300, manufactured by Denshyo Co., Ltd.) was dissolved in 90 g of tetrahydrofuran, and 7 g of a charge transporting substance having the following structural formula (VI) was dissolved therein. The charge transport layer coating solution thus obtained was dip coated onto the charge generation layer and dried at 130° C. for 20 minutes to form a charge transport layer with a thickness of about 20 μm. Invention product 2) was created.

Comparative Example 2 Acid Red 52 (Aizen Ac1d Rh
A comparative laminated electrophotographic photoreceptor (Comparative Example Product 2) was prepared in exactly the same manner as in Example 2 except that Odamine BH) was removed.
It was created.

These samples (2 types of photoreceptors according to the present invention, 2 types of comparative photoreceptors)
The characteristics of the photoreceptor were measured using an electrostatic paper analyzer SP-428 (Kawaguchi Electric Seisakusho Co., Ltd. 12) under the following conditions.

Charging 10 seconds (applied voltage - 6KV) Dark decay 1
Exposure for 0 seconds, exposure for 15 seconds (exposure intensity: 5 lux), and exposure under the above conditions for 30 minutes to fatigue the photoreceptor, and then further measure the characteristics of the photoreceptor.

The above results are shown in Table-1. However, the surface potential after 10 seconds of charging (2) Sensitivity: the amount of exposure required to reduce the surface potential to 1/10 after exposure (3) Residual potential: the surface potential after 15 seconds of exposure.

Table 1 [Effects] As is clear from the description of Examples, by containing a specific dye in the intermediate layer, a photoreceptor with less humidity dependence and less fatigue can be obtained.

Procedural amendment August 25, 1988 Patent Application No. 28'7209 2, Title of invention Electrophotographic photoreceptor 3, Person making the amendment Relationship to the case Patent applicant 1-chome Nakamagome, Ota-ku, Tokyo 3-6 (674) Ricoh Co., Ltd. Representative Hama 1) Hiro 4, Agent 4-5 Kojimachi, Chiyoda-ku, Tokyo (102) 5, Subject of amendment 6, Details of amendment ITl document, page 1, 13 ~14-line "Digital Copia"
followed by T (Copia is a registered trademark of Copia Co., Ltd.)
” to join.

Written amendment to the above procedure February 4, 1988 Patent Application No. 287209 of 1987 2 Name of the invention Electrophotographic photoreceptor 3 Person making the amendment Relationship to the case Patent applicant 1-chome Nakamagome, Ota-ku, Tokyo No. 3-6 (674) Ricoh Co., Ltd. Representative Hama 1) Hiro 4, Agent 4-5 Kojimachi, Chiyoda-ku, Tokyo (102) 6 Contents of amendment (1) Akira, lll 5 line 5 acid Correct the structural formula of Red 1.

(2) In the same book, page 11, line 3, amend "J approximately 20 μm thick to T approximately 20 μm thick."

(3) In the 5th line from the bottom of page 11 of Book A, ``Degree type'' is corrected to ``Ryo layer type''.

(4) rCM-400J, two lines from the bottom of page 11 of the same book
is corrected to F CM-4000j.

(5) “Hojutai Chemistry” on page 12, lines 2-3 of the same book as “
Hodogaya Chemical” is corrected.

(6) Environment 20℃ 15% in Table 1 on page 15 of the same book
The residual potential (V) of Example 1 is "1" at RH.
O, j, and also, in the ring @20°C, 15% RH, the words “Example 1” in the bottom three lines are corrected to “Comparative Example 1j.”

that's all

Claims (1)

[Claims] 1. An electrophotographic photoreceptor having an intermediate layer between a conductive substrate and a photosensitive layer and used repeatedly, characterized in that the intermediate layer contains a dye having a sodium sulfonate group. Electrophotographic photoreceptor.