JPH04356055A - electrophotographic photoreceptor - Google Patents

Abstract

PURPOSE:To provide an electrophotographic sensitive body having an intermediate layer which satisfies the requirements such as to prevent generation of interferential fringes. CONSTITUTION:This electrophotographic sensitive body consists of an intermediate layer and a photoconductive layer successively formed on a conductive substrate. The intermediate layer contains a titanium yellow pigment having >=0.3mum average particle size in a binder resin.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photoreceptor.

0002

[Prior Art] Conventionally, there is an electrophotographic photoreceptor having an intermediate layer.The functions of this intermediate layer are (1) excellent charging stability, (2) low residual potential, (3) prevention of interference fringes (coherent light In the case of an electrophotographic process using a writing light source as a writing light source) (4) It is possible to make a thick film, and it is possible to use a substrate with a poor surface. (5) It is possible to increase sensitivity.

[0003] Many intermediate layers have been proposed to realize these functions. For example, (a) A thin layer made only of resin. In this case, this has a certain degree of effect on the functions (1) and (2) above.

(b) A layer in which a pigment is dispersed in a resin.

In this case, there is a certain degree of effect on function (2), and depending on the type of pigment used, there is also an effect on function (3) and (5). That is, if the refractive index and pigment particle size are large, the effect (3) is obtained, and if the reflectance at the writing light wavelength is large, the effect (5) can be expected regardless of the type of substrate.

(c) A layer made only of resin is provided on a layer in which a conductive pigment is dispersed in resin.

In this case, the effects (1) to (4) can be expected.

However, in the case of (a), it is generally necessary to use a resin with relatively low resistance, and these resins are generally highly hygroscopic. Therefore, a photoreceptor using the intermediate layer (a) has a large environmental dependence, and the residual potential increases when the humidity is low, and the charging property decreases when the humidity is high.

In the case of (b), the characteristics of the photoreceptor are greatly influenced by the characteristics of the pigment used, and in particular, there are almost no pigments that can achieve both charging stability and low residual potential on their own, and in practice, they are not suitable for use as an intermediate layer. I can't say it's enough.

In the case of (c), it has a two-layer structure and requires many manufacturing steps, which is disadvantageous in terms of cost. Furthermore, since there is a layer made only of resin, there are the same drawbacks as in case (a).

As described above, the intermediate layer of the prior art has insufficient functionality and has drawbacks.

0012

SUMMARY OF THE INVENTION Under these circumstances, it is an object of the present invention to provide an electrophotographic photoreceptor that satisfies all of the functions required of the intermediate layer, including the prevention of interference fringes. It is.

[0013]

[Means for Solving the Problems] As a result of extensive studies, the present inventors have found that it is effective to use a specific pigment such as titanium yellow in the intermediate layer, and have arrived at the present invention.

That is, the present invention provides (1) an electrophotographic photoreceptor in which an intermediate layer and a photoconductive layer are sequentially provided on a conductive support, wherein the intermediate layer has an average particle size of 0.3 μm or more in a binder resin; (2) An electrophotographic photoreceptor comprising a titanium yellow pigment having a particle size of An electrophotographic photoreceptor containing a titanium yellow pigment and a titanium dioxide pigment having a particle size of 0.3 μm or more, (3
) An electrophotographic photoreceptor in which an intermediate layer and a photoconductive layer are sequentially provided on a conductive support, and the intermediate layer contains a titanium yellow pigment, a titanium dioxide pigment, and a titanium dioxide pigment having an average particle size of 0.3 μm or more in a binder resin. Contains stannic oxide (SnO2) powder, and the amount of titanium dioxide added is in the range of 0.1 to 10 parts by weight per 1 part by weight of titanium yellow, and the amount of stannic oxide added is equal to the amount of titanium yellow pigment and An electrophotographic photoreceptor characterized in that the amount of titanium pigment is 3 to 30% by weight based on the total weight of the titanium pigment, (4) an electrophotographic photoreceptor in which an intermediate layer and a photoconductive layer are sequentially provided on a conductive support, The intermediate layer contains a titanium yellow pigment with an average particle size of 0.3 μm or more, a titanium dioxide pigment, and indium oxide (In2O) in a binder resin.
3) Contains powder, and titanium dioxide is in the range of 0.1 to 10 parts by weight per 1 part by weight of titanium yellow, and the amount of indium oxide added is 3 to 10 parts by weight with respect to the total weight of titanium yellow pigment and titanium dioxide pigment. This is an electrophotographic photoreceptor characterized by having a content of 30% by weight.

The intermediate layer in the first aspect of the present invention comprises a resin layer containing titanium yellow as a pigment. Titanium yellow is a type of yellow pigment made from TiO2-NiO-Sb.
It consists of three components, 2O5, and develops color at a temperature of around 1000°C.

Even if this three-component composition is boiled with hydrochloric acid or sulfuric acid, Ni and Sb are not extracted or changed.
Ni and Sb atoms are Ti in the rutile crystal lattice of titanium oxide
It is considered to be in solid solution by substitution with atoms. Therefore, it is chemically and physically similar to rutile TiO2 to some extent and is extremely stable.

[0017] In addition, particles with an average particle size larger than that of white titanium oxide (approximately 0.4 to 1.2 μm) are commercially available, and by using them, even in the case of near-infrared light, the diffused reflection ability is high, and A photoreceptor with excellent electrostatic properties can be obtained.

The intermediate layer in the second aspect of the present invention contains titanium dioxide in addition to titanium yellow. This titanium dioxide has the effect of stabilizing the dispersion state of titanium yellow in the coating liquid, and preferably has an average particle size of 0.2 to 0.3 μm.

The amount of titanium dioxide to be used depends on its grade, but it is approximately 0.00% by weight per 1 part of titanium yellow.
A range of 1 to 10 is preferable. If it is less than 0.1, the effect will be small, and if it exceeds 10, the interference fringe prevention effect will be lost.

The intermediate layer in the third aspect of the present invention further contains titanium dioxide and stannic oxide in addition to titanium yellow. Further, in the fourth aspect of the present invention, the third aspect of the present invention
In place of stannic oxide in the invention, indium oxide (
In2O3). In these inventions, titanium dioxide has the effect of stabilizing the dispersion state of titanium yellow in the coating liquid, as in the second invention, and preferably 0.
Those having an average particle size of 2 to 0.3 μm are used.

[0021] The amount used depends on the grade of titanium dioxide, but it is preferably in the range of approximately 0.1 to 10 by weight per 1 of titanium yellow. If it is less than 0.1, the effect will be small, and if it exceeds 10, the interference fringe prevention effect will be lost.

Furthermore, in order to provide a photoreceptor on a substrate with a rough surface, it is necessary to increase the thickness of the intermediate layer, but in this case, a conductive pigment is added to suppress the increase in residual potential. It is desirable to add. However, when a conductive powder such as metal powder or carbon black is used, a grain-like background stain occurs in the background part in a process using a reversal development method. There are almost no conductive powders that do not have such drawbacks and have low absorption of near-infrared light, which is the wavelength of writing light from a semiconductor laser, in order to maintain high sensitivity. It was confirmed that the following conditions were satisfied. Therefore, titanium yellow, titanium dioxide,
By adding stannic dioxide or indium oxide, an intermediate layer that satisfies all of the functions (1) to (5) above can be obtained.

The amount of stannic oxide or indium oxide added is preferably about 3 to 30% by weight based on the total weight of the titanium yellow pigment and the titanium dioxide pigment. If it is less than 3%, there is no effect of adding stannic oxide, and if it exceeds 30%, the charging stability of the photoreceptor will deteriorate.

[0024] Furthermore, the ratio P/R of the sum of the titanium yellow pigment, titanium dioxide pigment, and stannic oxide powder or indium oxide powder to the binder resin (R) is 1 in terms of volume ratio.
/1 to 3/1 is preferred. When the P/R volume ratio of the intermediate layer is less than 1, the intermediate layer is influenced by the properties of the binder resin, and in particular, the characteristics of the photoreceptor change with changes in temperature and humidity. Furthermore, if the P/R ratio exceeds 3, the intermediate layer will have many voids and air will accumulate therein. These become bubbles when the photoconductive layer is applied and dried, resulting in coating film defects.

The electrophotographic photoreceptor of the present invention comprises the above-mentioned intermediate layer provided on a conductive substrate and a photosensitive layer thereon.

[0026] As the conductive substrate, 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 Examples include those coated with conductive paint.

Any suitable resin can be used for the intermediate layer, but considering that the photosensitive layer will be coated on top of it with a solvent, it is recommended to use a resin that has high solvent resistance to common organic solvents. desirable. As such resin,
Water-soluble resins such as polyvinyl alcohol, casein, and sodium polyacrylate; Alcohol-soluble resins such as copolymerized nylon and methoxymethylated nylon; Curable resins that form three-dimensional network structures such as polyurethane, melamine resin, and epoxy resin. Can be mentioned.

[0028] To obtain the intermediate layer on the conductive substrate, titanium yellow, or titanium yellow and titanium dioxide, and tin oxide or indium oxide may be dispersed in a solution of the above resin, and the mixture may be coated and dried by a dip coating method or the like. .

The thickness of the intermediate layer is preferably about 0.3 to 30 μm. If the thickness is less than 0.3 μm, film forming properties are poor, and if it exceeds 30 μm, it becomes difficult to achieve both charging stability and low residual potential.

The photoconductive layer used in the present invention includes (1) a charge transfer complex formed by a combination of an electron-donating compound and an electron-accepting compound (described in US Pat. No. 3,484,237), and (2) a dye in an organic photoconductor. (described in Japanese Patent Publication No. 48-25658); (3) pigments dispersed in a hole- or electron-active matrix (Japanese Patent Application Laid-open Nos. 47-30328 and 18545-1982);
(4) functionally separated charge generation layer and charge transport layer (described in JP-A-49-105537), (5) mainly composed of a eutectic complex consisting of a dye and a resin. Conventional methods such as those in which an organic pigment or an inorganic charge generating material is added to a charge transfer complex (described in Japanese Patent Application Laid-open No. 49-91648) It may be formed of any organic photoconductor known from .

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

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

The charge transporting layer is made of a charge transporting substance such as an α-phenylstilbene compound (described in JP-A-58-198043) or a hydrazone compound (described in JP-A-55-46760) that has film-forming properties. It may be dissolved in a resin such as polyester, polysulfone, polycarbonate, polymethacrylic acid ester, polystyrene, etc., and coated on the charge generation layer to a thickness of about 10 to 40 μm. The film-forming resin is used here because the charge transporting substance generally has a low molecular weight and has poor film-forming properties by itself.

[0034]

【Example】

Example 1 Alcohol-soluble polyamide resin {Amilan CM-80
00 (manufactured by Toray)} 1 part by weight, 8 parts by weight of methanol, n-
It was dissolved in a mixed solvent containing 5 parts by weight of butanol. To this was added 1 part by weight of titanium yellow powder {Typaque Yellow TY-50 (manufactured by Ishihara Sangyo)}, and the mixture was dispersed in a ball mill for 12 hours to prepare a coating liquid for an intermediate layer. This was applied to an aluminum cylinder having a mirror-finished surface and having an outer diameter of 80 mm and a length of 359 mm, and was dried to form an intermediate layer so that the film thickness after drying was 1.5 μm.

Next, butyral resin {S-LEC BLS (
Sekisui Chemical Co., Ltd.)} was dissolved in 150 parts by weight of cyclohexanone, 10 parts by weight of a trisazo pigment having the following structural formula was added thereto, and the mixture was dispersed in a ball mill for 48 hours.

[0036]

[Chemical formula 1]

Further, 210 parts by weight of cyclohexanone was added and dispersion was carried out for 3 hours. This was diluted with cyclohexanone while stirring so that the solid content was 1.5 wt%. The charge generation layer coating liquid thus obtained was applied onto the intermediate layer and dried to form a charge generation layer having a thickness of about 0.2 μm.

Furthermore, 6 parts by weight of a charge transport substance having the following structural formula,
Polycarbonate resin {Panlite K-1300 (manufactured by Teijin Chemicals)} 10 parts by weight, silicone oil {KF-50 (
Shin-Etsu Chemical Co., Ltd.)} 0.002 parts by weight was dissolved in 90 parts by weight of methylene chloride. The charge transport layer coating liquid thus obtained was applied onto the charge generation layer and dried to form a charge transport layer having a thickness of 23 μm, thereby producing an electrophotographic photoreceptor.

[0039]

[Case 2]

Comparative Example 1 An electrophotographic photoreceptor was prepared in the same manner as in Example 1 except that the titanium yellow in the intermediate layer of Example 1 was removed and an intermediate layer of 0.5 μm thick made of polyamide resin was provided.

The photoreceptor obtained above was installed in a digital copying machine {Imagio 420 (manufactured by Ricoh)}, and a copy was made by selecting the text photo mode using orange paper as a document. Although an image with uniform halftones was obtained, in Comparative Example 1, unevenness in density of the image, which was clearly considered to be interference fringes, was observed.

Example 2 Acrylic resin {Acrydic A-460-60 (Dainippon Ink & Chemicals)} 15 parts by weight, melamine resin {Superbeckamine L-121-60 (Dainippon Ink & Chemicals)} 10 Part by weight was dissolved in 100 parts by weight of methyl ethyl ketone. Add 50 parts by weight of titanium yellow powder {Typeque Yellow TY-70S (manufactured by Ishihara Sangyo)} to this,
The mixture was dispersed in a ball mill for 12 hours to prepare a coating solution for an intermediate layer. This was coated and dried on the same aluminum cylinder as in Example 1 so that the film thickness after drying was 2.0 μm to form an intermediate layer.

Next, a charge generation layer similar to that in Example 1 was formed on the intermediate layer.

Furthermore, a charge transport substance having the following structural formula:

0045
]

[Chemical formula 3]

[0046]

8 parts by weight Polycarbonate resin {Panlite K-1300 (manufactured by Teijin Kasei)}
10 parts by weight Silicone oil {KF-50 (manufactured by Shin-Etsu Chemical)
0.002 parts by weight Butylated hydroxytoluene

0.04 parts by weight was dissolved in 86 parts by weight of methylene chloride. The charge transport layer coating liquid thus obtained was applied onto the charge generation layer and dried to form a charge transport layer with a thickness of 20 μm, thereby producing an electrophotographic photoreceptor.

Comparative Example 2 An electrophotographic photoreceptor was prepared in the same manner as in Example 2, except that titanium oxide powder {Tiepeke R-680 (manufactured by Ishihara Sangyo) was used instead of titanium yellow in the intermediate layer of Example 2.

The photoreceptor obtained above was evaluated using Imageo 420 in the same manner as in Example 1. In Example 2, an image with uniform halftones was obtained, but in Comparative Example 2, although there was slight interference, Uneven shading in the image, which is considered to be stripes, was confirmed.

Examples 3 to 5 Comparative Examples 3 and 4 Acrylic resin {
Acrylic resin A460-60 (manufactured by Dainippon Ink and Chemicals) 15 parts by weight, melamine resin {Super Beckamine L
-121-60 (manufactured by Dainippon Ink & Chemicals)}10 parts by weight were dissolved in 100 parts by weight of methyl ethyl ketone. Add titanium yellow powder {Type Yellow TY-70 (
Ishihara Sangyo)} and titanium dioxide powder {Tiepeke A-1
00 (manufactured by Ishihara Sangyo)} in the amounts shown in Table 1, and dispersed in a ball mill for 6 hours to prepare an intermediate layer coating solution. This was applied to the same aluminum cylinder as in Example 1 by dip coating so that the film thickness after drying was 2.0 μm, and dried at 130° C. for 20 minutes to form an intermediate layer.

[0050]

[Table 1]

Next, a charge generation layer similar to that in Example 1 was formed.

Furthermore, the following charge transport substance II

[0053]

[C4]

[0054]

8 parts by weight Polycarbonate resin {Panlite K-1300 (manufactured by Teijin Kasei)}

10 parts by weight silicone oil {K
F-50 (manufactured by Shin-Etsu Chemical)
0.00
2 parts by weight Butylated hydroxytoluene

0.04 parts by weight was dissolved in 86 parts by weight of methylene chloride.

The charge transport layer coating liquid thus obtained was coated on the charge generation layer and dried to form a charge transport layer with a thickness of 20 μm, thereby producing an electrophotographic photoreceptor.

[0056] The photoreceptor obtained above was used in a digital copying machine {
Imagio 420 (manufactured by Ricoh)], the text photo mode was selected using orange paper as the original, and copies were made, and the results shown in Table 2 were obtained.

[0057]

[Table 2]

Examples 6 to 8, Comparative Examples 5 and 6 Twenty parts by weight of alcohol-soluble polyamide resin {Amilan CM-8000 (manufactured by Toray Industries, Ltd.)} were dissolved in a mixed solvent of 160 parts by weight of methanol and 80 parts by weight of n-butanol. Add to this titanium yellow powder {Typaque Yellow TY-5
0 (manufactured by Ishihara Sangyo)} and titanium dioxide powder {Tipeque C
R-EL (manufactured by Ishihara Sangyo)} were added in the amounts shown in Table 3, and dispersed in a ball mill for 6 hours to prepare an intermediate layer coating solution.

[0059]

[Table 3]

[0060] This was coated on the same aluminum cylinder as in Examples 3 to 5 by dip coating so that the film thickness after drying was 3.5 μm, and dried at 120° C. for 15 minutes to form an intermediate layer.

Next, butyral resin {S-LEC BLS
(manufactured by Sekisui Chemical)} was dissolved in 60 parts by weight of cyclohexanone, 3 parts by weight of titanyl phthalocyanine was added thereto, and the mixture was dispersed in a ball mill for 24 hours. Furthermore, 80 parts by weight of cyclohexanone was added and the mixture was dispersed for 3 hours. This was diluted with methyl ethyl ketone while stirring so that the solid content was 2.5 wt%.

The charge generation layer coating liquid thus obtained was applied onto the intermediate layer and dried to form a charge generation layer having a thickness of about 0.4 μm.

[0063] Furthermore, the following charge transport material III

8 parts by weight

[0064]

[C5]

Polycarbonate resin {Panlite K-130
0 (made by Teijin Chemicals)}
10 parts by weight
Silicone oil {KF-50 (manufactured by Shin-Etsu Chemical)}
0.002 parts by weight Butylated hydroxytoluene
0.04 parts by weight was dissolved in 88 parts by weight of methylene chloride.

The charge transport layer coating liquid thus obtained was coated on the charge generation layer and dried to form a charge transport layer with a thickness of 20 μm, thereby producing an electrophotographic photoreceptor.

[0067] The photoreceptor obtained above was used in a digital copying machine {
Imagio 420 (manufactured by Ricoh)], the text photo mode was selected using orange paper as the original, and copies were made, and the results shown in Table 4 were obtained.

[0068]

[Table 4]

Examples 9 to 11, Comparative Examples 7 to 9 Acrylic resin {Acridic A-460-60 (manufactured by Dainippon Ink and Chemicals)}
18 parts by weight
Melamine resin {Super Beckamine L-121-
60 (manufactured by Dainippon Ink and Chemicals)

Dissolve 12 parts by weight in 60 parts by weight of methyl ethyl ketone,
This is titanium yellow pigment {Typaque Yellow TY-5
0 (manufactured by Ishihara Sangyo)}, titanium dioxide pigment {Tiepeque A
-100 (manufactured by Ishihara Sangyo)} and tin oxide powder (manufactured by Mitsubishi Metals) were added in the amounts shown in Table 5, and dispersed in a ball mill for 8 hours to prepare an intermediate layer coating solution.

[0070]

[Table 5]

[0071] This was coated by dip coating on the same aluminum cylinder as in Example 1, and dried at 140°C for 20 minutes to form an intermediate layer.

Next, a charge generation layer similar to that in Example 1 was formed.

Furthermore, 6 parts by weight of a charge transport material of the following formula IV,
Polycarbonate resin {Panlite K-1300 (manufactured by Teijin Chemicals)} 10 parts by weight, silicone oil {KF-50 (
(manufactured by Shin-Etsu Chemical Co., Ltd.)} and 0.06 parts by weight of butylated hydroxytoluene (BHT) were dissolved in 90 parts by weight of methylene chloride. The charge transport layer coating solution thus obtained was applied onto the charge generation layer and dried to a thickness of 23 μm.
A charge transport layer was formed to produce an electrophotographic photoreceptor.

[0074]

[C6]

[0075] The photoreceptor obtained above was used in a digital copying machine {
Imagio 420 (manufactured by Ricoh)] was used as an original on orange paper, and a copy was obtained in text photo mode. Table 6
I got the result.

[0076]

[Table 6]

Examples 12 to 14, Comparative Examples 10 and 11
Alkyd resin {Beccosol 1307-60EL
, solid content 60% by weight (manufactured by Dainippon Ink Chemical)}
45 parts by weight
Melamine resin {Super Beckamine L-121-6
0 solid content 60% by weight (manufactured by Dainippon Ink Chemical)}
Dissolve 30 parts by weight in 150 parts by weight of methyl ethyl ketone, and add titanium yellow pigment {Typeque Yellow TY-70 (manufactured by Ishihara Sangyo)}, titanium dioxide pigment {Typek CR-EL (manufactured by Ishihara Sangyo)} and tin oxide powder (Mitsubishi). (metal) were added in the amounts shown in Table 7, and dispersed in a ball mill for 8 hours to prepare a coating solution for an intermediate layer. Each powder (P) at this time
The volume ratio P/R of binder resin (R) and binder resin (R) is also shown in Table 7 (the density of the materials is 4.4 for TY-70, 4.2 for CR-EL, 7.0 for tin oxide, and 1.0 for alkyd melamine resin). 3)
.

[0078]

[Table 7]

[0079] This was coated by dip coating on the same aluminum cylinder as in Example 1, and dried at 150°C for 20 minutes to give a thickness of 13μ.
An intermediate layer of m was formed. Next, a charge generation layer and a charge transport layer similar to those in Example 9 were formed to produce an electrophotographic photoreceptor. As a result, in Comparative Example 11, bubbles were generated during drying of the charge transport layer, and a photoreceptor worthy of evaluation was not obtained.

The photoreceptor obtained above was evaluated in the same manner as in Example 9, and the results are shown in Table 8.

[0081]

[Table 8]

Example 15 The intermediate layer coating solution of Example 12 was coated with a diameter of 80 mm and a length of 3 mm.
The coating was applied by dip coating onto an aluminum cylinder whose surface was processed to have a maximum surface roughness of 7 μm with a diameter of 59 mm, and dried at 150° C. for 20 minutes to form an intermediate layer with a thickness of 15 μm. A charge generation layer and a charge transport layer similar to those in Example 9 were formed on this to obtain an electrophotographic photoreceptor.

[0083] When this was evaluated in the same manner as in Example 9, 50
Good images were obtained even after copying.

Examples 16 to 18, Comparative Examples 12 to 15
Acrylic resin {Acrydic A-460-60
(Manufactured by Dainippon Ink and Chemicals)
18 parts by weight Melamine resin {Super Beckamine L-121
-60 (Dainippon Ink & Chemicals)}
1
Dissolve 2 parts by weight in 60 parts by weight of methyl ethyl ketone, and add titanium yellow pigment {Typaque Yellow TY-50
(manufactured by Ishihara Sangyo)}, titanium dioxide pigment {Tiepeque A-
100 (manufactured by Ishihara Sangyo)} and indium oxide powder (manufactured by Mitsubishi Metals) were added in the amounts shown in Table 9, and dispersed in a ball mill for 8 hours to prepare an intermediate layer coating solution.

[0085]

[Table 9]

[0086] This was applied by dip coating onto an aluminum drum with a mirror-finished surface, 80 mm in diameter and 360 mm in length, and heated at 140°C.
The mixture was dried for 20 minutes to form an intermediate layer.

Next, butyral resin {S-LEC BLS (
Sekisui Chemical Co., Ltd.)} was dissolved in 150 parts by weight of cyclohexanone, 10 parts by weight of a trisazo pigment having the following structural formula was added thereto, and the mixture was dispersed in a ball mill for 48 hours.

[0088]

[C7]

Further, 210 parts by weight of cyclohexanone was added and dispersion was carried out for 3 hours. This was diluted with cyclohexanone while stirring so that the solid content was 1.5 wt%. The charge generation layer coating liquid thus obtained was applied onto the intermediate layer and dried to form a charge generation layer having a thickness of about 0.2 μm.

Furthermore, 6 parts by weight of a charge transport substance having the following structural formula,
Polycarbonate resin {Panlite K-1300 (manufactured by Teijin Chemicals)} 10 parts by weight, silicone oil {KF-50 (
Shin-Etsu Chemical Co., Ltd.)] and 0.06 parts by weight of butylated hydroxytoluene (BHT) were dissolved in 90 parts by weight of methylene chloride. The charge transport layer coating liquid thus obtained was applied onto the charge generation layer and dried to form a charge transport layer having a thickness of 23 μm, thereby producing an electrophotographic photoreceptor.

[0091]

[Chemical formula 8]

The photoreceptor obtained above was installed in a digital copying machine {Imagio 420 (manufactured by Ricoh)}, and copies were made in the text/photo mode using orange paper as the original, and the following results were obtained.

[0093]

[Table 10]

Examples 19-21 Alkyd resin {Beccosol 1307-60
EL, solid content 60% by weight (Dainippon Ink Chemical)}
Part by weight Melamine resin {Super Beckamine L-121-
60 Solid content 60% by weight (manufactured by Dainippon Ink and Chemicals)
} Dissolve parts by weight in parts by weight of methyl ethyl ketone, and add titanium yellow pigment {Tiepeke Yellow TY-70S (manufactured by Ishihara Sangyo)} and titanium dioxide pigment {Tiepeke CR-E].
L (manufactured by Ishihara Sangyo)} and indium oxide powder (manufactured by Mitsubishi Metals) were added in the amounts shown in Table 11, and milled with a ball mill.
A coating solution for an intermediate layer was prepared by dispersing the mixture over time. The volume ratio P/R of each powder (P) and binder resin (R) at this time is also shown in Table 3 (the density of the material is 4.4 for TY-70, C
R-EL: 4.2, indium oxide: 7.2, alkyd melamine resin: 1.3).

[0095]

[Table 11]

[0096] This was coated by dip coating on the same aluminum cylinder as in Example 16, and dried at 150°C for 20 minutes to a thickness of 13.
An intermediate layer of .mu.m was formed. Next, a charge generation layer and a charge transport layer similar to those in Example 16 were formed to produce an electrophotographic photoreceptor. As a result, in Comparative Example 17, bubbles were generated during drying of the charge transport layer, and a photoreceptor worthy of evaluation was not obtained. The photoreceptor obtained above was evaluated in the same manner as in Example 16,
The results are shown in Table 12.

[0097]

[Table 12]

Example 22 The intermediate layer coating solution of Example 19 was coated with a diameter of 80 mm and a length of 3
The coating was applied by dip coating onto an aluminum cylinder whose surface was processed to a maximum surface roughness of 7 μm with a thickness of 60 mm, and dried at 150° C. for 20 minutes to form an intermediate layer with a thickness of 15 μm. A charge generation layer and a charge transport layer similar to those in Example 1 were formed on this to obtain an electrophotographic photoreceptor. When this was evaluated in the same manner as in Example 16, it was found to be 5.
Good images were obtained even after 0 copies were made.

0099

As explained above, according to the present invention, an electrophotographic image with excellent image characteristics can be formed by employing a specific intermediate layer.

Claims (6)

[Claims] 1. An electrophotographic photoreceptor comprising an intermediate layer and a photoconductive layer provided in this order on a conductive support, wherein the intermediate layer comprises a titanium yellow pigment having an average particle size of 0.3 μm or more in a binder resin. An electrophotographic photoreceptor comprising: 2. An electrophotographic photoreceptor in which an intermediate layer and a photoconductive layer are sequentially provided on a conductive support, wherein the intermediate layer contains a titanium yellow pigment having an average particle size of 0.3 μm or more in a binder resin, and carbon dioxide. An electrophotographic photoreceptor characterized by containing a titanium pigment. 3. An electrophotographic photoreceptor in which an intermediate layer and a photoconductive layer are sequentially provided on a conductive support, wherein the intermediate layer contains a titanium yellow pigment having an average particle size of 0.3 μm or more and a titanium dioxide pigment in a binder resin. Titanium pigment and stannic oxide (SnO2)
Contains powder, and the amount of titanium dioxide added is in the range of 0.1 to 10 parts by weight per 1 part by weight of titanium yellow, and the amount of stannic oxide added is based on the total weight of titanium yellow pigment and titanium dioxide pigment. , 3 to 30% by weight. 4. The total amount (P) of titanium yellow pigment, titanium dioxide pigment, and stannic oxide powder in claim 3.
The ratio P/R of and binder resin (R) is 1/1 to 3 in terms of volume ratio.
An electrophotographic photoreceptor characterized in that: /1. 5. An electrophotographic photoreceptor in which an intermediate layer and a photoconductive layer are sequentially provided on a conductive support, wherein the intermediate layer contains a titanium yellow pigment having an average particle size of 0.3 μm or more, and a titanium dioxide pigment in a binder resin. Titanium pigment, and indium oxide (In2O
3) Contains powder, and titanium dioxide is in the range of 0.1 to 10 parts by weight per 1 part by weight of titanium yellow, and the amount of indium oxide added is 3 to 10 parts by weight with respect to the total weight of titanium yellow pigment and titanium dioxide pigment. An electrophotographic photoreceptor characterized in that the content is 30% by weight. 6. A titanium yellow pigment according to claim 5,
Total of titanium dioxide pigment and indium oxide powder (P
) and the binder resin (R) (P/R ratio) is 1 in volume ratio.
1. An electrophotographic photoreceptor characterized in that the photoreceptor has a photoreceptor having a photoresistance of 1/1 to 3/1.