JPH1063021A - Electrophotgraphic photoreceptor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of an abnormal image such as an image thickened in character or blurred image even in repetitive use, by forming an electric charge generating layer contg. a specified electric charge generating material and specifying the oxygen permeation factor of an electric charge transferring layer. SOLUTION: This electrophotographic photoreceptor has an electric charge generating layer and an electric charge transferring layer on the substrate, the electric charge generating layer contains at least an electric charge generating material represented by the formula (where each of R<1> and R<2> is alkyl, alkoxy, halogen or H) and the oxygen permeation factor of the electric charge transferring layer is <=3×10<-11> cm<3> .cm/cm<2> .sec.cmHg. Since the mobility of electric charges on the surface of the electric charge transferring layer and at the interface between both the layers in the transverse direction can be reduced, the occurrence of an abnormal image such as an image thickened in character or blurred image can be prevented even in repetitive use.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an organic electrophotographic photosensitive member having a charge generation layer and a charge transport layer on a support.

[0002]

2. Description of the Related Art Organic electrophotographic photoreceptors are less polluting and have higher productivity than inorganic electrophotographic photoreceptors. In recent years, electrophotographic copiers and printers have been remarkably developed. For this reason, those having various performances have been developed, but still have a problem in durability.

For the purpose of improving ozone resistance (suppression of penetration of ozone into the photosensitive layer) to improve the photoreceptor characteristics or image characteristics (fog, white spots) upon repeated use, see, for example, Japanese Patent Application Laid-Open No. Japanese Patent Application Laid-Open No. 53357/1993 specifies the nitrogen transmission coefficient of the protective layer, JP-A-6-161134 specifies the oxygen transmission coefficient of the charge transport layer, and JP-A-7-152162 specifies the oxygen transmission coefficient of the photosensitive layer. Has been proposed. However, simply defining the gas permeability coefficient of the photosensitive layer or the like is not sufficient for thickening the characters of an image due to repeated use of the photosensitive member, image blur, and the like.

In Japanese Patent Application Laid-Open No. Hei 2-28661,
In order to improve red reproducibility, at least two types of azo pigments having a specific structure are disclosed in JP-A-5-341546 and JP-A-6-49433. JP-A-3-37664 proposes a photoreceptor having a photosensitive layer (or charge generation layer) in which an azo pigment having a specific structure and titanyl phthalocyanine are mixed, respectively, in order to expand the photosensitive wavelength range. . Japanese Patent Application Laid-Open No. 6-49433 discloses ozone and NOx.
The purpose of the invention is to prevent the deterioration of the charging characteristics due to the use of a photosensitive member, but it does not mention improvement of thickening of an image or blurring of an image due to repeated use of a photoreceptor. Other publications do not describe improvements in image-related properties.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and an electrophotographic photoreceptor capable of preventing occurrence of an abnormal image such as thickening of an image and blurring of an image by repeated use. The purpose is to provide.

[0006]

According to the present invention, in an electrophotographic photoreceptor having a charge generation layer and a charge transport layer on a support, the charge generation layer has at least a charge represented by the following general formula (I). Including the generated substance, the oxygen transport coefficient of the charge transport layer is 3 × 10 ⁻¹¹ cm ³ · cm / cm ² · sec · c
An electrophotographic photoreceptor characterized by having an mHg or less is provided.

Embedded image (In the formula, R ¹ and R ² each represent an alkyl group, an alkoxy group, a halogen atom or a hydrogen atom, which may be the same or different.)

In the electrophotographic photoreceptor of the present invention, the charge generation layer contains at least the charge generation material represented by the general formula (I), and the charge transport layer has an oxygen transmission coefficient of 3 × 10 ^-11 c.
Since it is set to be not more than m ³ · cm / cm ² · sec · cmHg, abnormal images such as thickening of characters of images and blurring of images are not generated even when repeatedly used.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The electrophotographic photoreceptor of the present invention will be described below in detail. As described above, the electrophotographic photoreceptor of the present invention comprises (1) the charge generation layer containing at least the charge generation substance represented by the general formula (I), and (2) the oxygen transport coefficient of the charge transport layer. 3 × 10 ^-11 cm ³ · cm / cm
It is not more than ² · sec · cmHg.

The charge generation layer comprises the charge generation material represented by the general formula (I) alone or, if necessary, a binder resin.
It is formed by applying a charge generating layer coating solution milled together with an organic solvent such as cyclohexanone, methyl ethyl ketone, tetrahydrofuran, ethyl cellosolve, etc. onto a support. Of course, in addition to the charge generating substance represented by the general formula (I), a perylene pigment,
Trisazo pigments, phthalocyanine pigments and the like can also be added.

Table 1 shows preferred specific examples of the charge generating material represented by the general formula (I).

[0011]

[Table 1]

As the binder resin for the charge generation layer, polyamide, polyurethane, polyester, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, poly-N-vinyl carbazole And polyacrylamide.
The amount of the binder resin is 5 to 100 parts by weight of the charge generating substance.
The appropriate amount is from 100 to 100 parts by weight, preferably from 10 to 50 parts by weight. The thickness of the charge generation layer is 0.01 to 2 μm, preferably 0.1 to 1 μm.

In the present invention, the oxygen transport coefficient of the charge transport layer is 3 × 10 ⁻¹¹ cm ³ · cm / cm ² · sec · cm.
Although it is set to Hg or less, the oxygen permeability coefficient of the charge transport layer can be set to the value or less by appropriately selecting the charge transport material, the binder resin, and the film thickness of the charge transport layer. Table 2 shows preferred specific examples of the charge transport material used in the present invention.

[0014]

[Table 2]

The charge transport layer comprises a charge transfer material, a binder resin,
If necessary, it is formed by dissolving a plasticizer, a leveling agent, and an antioxidant in a suitable solvent and applying the solution on the charge generation layer. Examples of the binder resin include thermoplastic or thermosetting resins such as polystyrene, polyester, polycarbonate, polyvinyl chloride, phenoxy, acrylic, silicone, melamine, urethane, phenol, and epoxy.

As the solvent for coating the charge transport layer, 1,
1,2-trichloroethane, 1,2-dichloroethane,
Dioxane, toluene, monochlorobenzene, tetrahydrofuran, cyclohexanone, dichloromethane and the like can be used alone or as a mixture of two or more.

[0017] If necessary, a protective layer can be provided on the charge transport layer. The protective layer is a layer in which a metal or metal oxide ultrafine powder is dispersed in a binder resin. As a binder resin, it is virtually transparent to visible and infrared light,
Those having excellent electrical insulation, mechanical strength, and adhesiveness are desirable.

The undercoat layer is made of a thermoplastic resin such as polyamide, polyvinyl alcohol, casein, ethylcellulose, etc .; a thermosetting resin such as acryl, phenol, melamine, alkyd, unsaturated polyester, epoxy or the like; or a titanium oxide, zinc oxide or the like. A dispersion of a pigment such as carbon is used, and the film thickness is about 0.2 to 12 μm.

As the support, aluminum, nickel, chromium, copper, tin oxide, indium oxide or the like is vapor-deposited on a sheet-like or seamless belt-like plastic film to form an endless belt, nickel, iron, beryllium-copper alloy, etc. Belt, aluminum, nickel-cobalt alloy, stainless steel, etc.
I, I.I. I. A tube or the like which is formed into a tube by a method such as extrusion or drawing and then surface-treated by cutting, superfinishing, polishing or the like can be used.

[0020]

The present invention will be described more specifically with reference to the following examples. In addition, the part shown in an Example means a weight part.

Example 1 A mixture having the following composition was placed in a ball mill pot,
Using an alumina ball of m, ball milling was performed for 48 hours to prepare an undercoat layer coating solution. This coating solution is φ30m
m, after coating on an aluminum drum-shaped support having a length of 301 mm,
After drying at 130 ° C. for 20 minutes, an undercoat layer having a thickness of 2.8 μm was formed. Titanium oxide (KR-310; manufactured by Titanium Industries) 12 parts Acrylic resin (A-405; manufactured by Dainippon Ink) 4.6 parts Melamine resin (L-121-60; manufactured by Dainippon Ink) 1.7 parts Methyl ethyl ketone (Kanto Chemical) 10.6 parts

Next, Compound No. 11 charge generating substances 3
Part, polyvinyl butyral resin 1 part (S-REC BL
S: Sekisui Chemical Co., Ltd.) and a mixture consisting of 80 parts of cyclohexanone (Kanto Chemical Co., Ltd.) were placed in a ball mill pot,
After ball milling for 48 hours using a SUS ball of φ10 mm, 116 parts of cyclohexanone was further added to prepare a charge generating layer coating solution. This coating solution was applied on the undercoat layer and dried at 130 ° C. for 20 minutes to form a 0.2 μm thick charge generation layer.

Subsequently, a charge transport layer coating solution having the following composition was prepared, applied on the charge generation layer, and dried at 110 ° C. for 20 minutes to form a charge transport layer having a thickness of 25 μm, thereby producing an electrophotographic photosensitive member. did. Compound No. 29 charge transport materials (Ricoh) 8 parts Polycarbonate resin (C-1400; Teijin Chemicals) 10 parts Dichloromethane (Kanto Chemical) 88 parts Silicone oil (KF-50; Shin-Etsu Chemical) 0.0002 Department

Example 2 In Example 1, the charge-transporting substance was Compound No. 31
An electrophotographic photoreceptor was produced in exactly the same manner as in Example 1, except that the photoreceptor was changed to (manufactured by Ricoh Company).

Example 3 In Example 2, the charge-generating substance was Compound No. An electrophotographic photoreceptor was produced in exactly the same manner as in Example 2 except that the composition was changed to 25.

Example 4 In Example 3, the polycarbonate resin was replaced with TS-20.
50: An electrophotographic photoreceptor was produced in exactly the same manner as in Example 3, except that the product was changed to Teijin Chemicals Ltd.

Example 5 In Example 3, the charge transport material was changed to Compound No. 36
An electrophotographic photoreceptor was produced in exactly the same manner as in Example 3, except that the photoreceptor was changed to (manufactured by Ricoh Company).

Example 6 In Example 4, the charge-transporting substance was Compound No. 33
An electrophotographic photoreceptor was produced in exactly the same manner as in Example 4, except that the photoreceptor was changed to (Ricoh).

Example 7 In Example 4, the charge generation substance was changed to Compound No. 17
(Manufactured by Ricoh Co., Ltd.) and the charge transport substance is Compound N
o. An electrophotographic photosensitive member was produced in exactly the same manner as in Example 4 except that the electrophotographic photosensitive member was changed to 34 (manufactured by Ricoh Company).

Example 8 In Example 7, the charge transport material was changed to Compound No. 32
(Manufactured by Ricoh Co., Ltd.) and the polycarbonate resin is C
-1400: An electrophotographic photoreceptor was produced in exactly the same manner as in Example 7, except that the product was changed to Teijin Chemicals Ltd.

Example 9 In the same manner as in Example 1, an undercoat layer was formed on an aluminum drum-shaped support having a diameter of 30 mm and a length of 301 mm. Next, Compound No. 17, 1 part of a charge generating substance represented by the following formula (II) (3 parts) (available from Ricoh Company), 1.3 parts of a polyvinyl butyral resin (Eslek BLS; manufactured by Sekisui Chemical Co., Ltd.), cyclohexanone (Kanto Chemical Co., Ltd.) The mixture consisting of 80 parts was placed in a ball mill pot, and φ10 mmSUS
After ball milling for 48 hours using a ball, 116 parts of cyclohexanone was further added to prepare a charge generating layer coating solution. This coating solution is applied on the undercoat layer at 130 ° C. for 20 minutes.
After drying for 0.2 minute, a charge generation layer having a thickness of 0.2 μm was formed.

[0032]

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Subsequently, a coating solution for a charge transport layer having the following composition was prepared, applied on the charge generation layer, and dried at 110 ° C. for 20 minutes to form a charge transport layer having a thickness of 25 μm, thereby producing an electrophotographic photosensitive member. . Compound No. 31 charge transport materials (Ricoh) 7 parts Polycarbonate resin (C-1400; Teijin Chemicals) 10 parts Dichloromethane (Kanto Chemical) 83 parts Silicone oil (KF-50; Shin-Etsu Chemical) 0.0002 Department

Example 10 In Example 9, the charge transport material was Compound No. An electrophotographic photoreceptor was produced in exactly the same manner as in Example 9 except that the photoconductor was changed to 32.

Example 11 In Example 9, the charge transport material was Compound No. An electrophotographic photoreceptor was prepared in exactly the same manner as in Example 9, except that the resin was changed to TS-2050 and manufactured by Teijin Chemicals Limited.

Example 12 An undercoat layer was formed on an aluminum drum-shaped support having a diameter of 30 mm and a length of 301 mm in the same manner as in Example 1. Next, Compound No. 1.5 parts of the charge-generating substance of the formula (III)
A mixture consisting of 1.5 parts of a charge-generating substance represented by the following formula, 1 part of polyvinyl butyral resin (Eslec BLS; manufactured by Sekisui Chemical Co., Ltd.), and 80 parts of cyclohexanone (manufactured by Kanto Chemical Co., Ltd.) is placed in a ball mill pot, and a φ10 mm SUS ball is used. After ball milling for 48 hours, 116 parts of cyclohexanone was further added to prepare a charge generating layer coating solution. This coating solution was applied on the undercoat layer and dried at 130 ° C. for 20 minutes to form a 0.2 μm thick charge generation layer.

[0037]

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Subsequently, a charge transport layer was formed in exactly the same manner as in Example 4 to produce an electrophotographic photosensitive member.

Example 13 In Example 12, the charge transport material was changed to Compound No. 29
, And the polycarbonate resin was changed to C-1400; manufactured by Teijin Chemicals Limited, except that an electrophotographic photoreceptor was produced in exactly the same manner as in Example 12.

Example 14 In Example 13, the charge transport material was changed to Compound No. 36
An electrophotographic photoreceptor was produced in exactly the same manner as in Example 13 except that the above was changed.

Example 15 In the same manner as in Example 1, an undercoat layer was formed on an aluminum drum-shaped support having a diameter of 30 mm and a length of 301 mm. Next, Compound No. 1 part of the charge generating substance, 2 parts of the charge generating substance represented by the formula (II), and polyvinyl butyral resin 1
A mixture composed of 80 parts (Eslek BLS; manufactured by Sekisui Chemical Co., Ltd.) and 80 parts of cyclohexanone (manufactured by Kanto Kagaku Co., Ltd.) was placed in a ball mill pot, and 4 mm
After ball milling for 8 hours, add cyclohexanone 1
16 parts were added to prepare a charge generating layer coating solution. This coating solution was applied on the undercoat layer and dried at 130 ° C. for 20 minutes to form a 0.2 μm thick charge generation layer. Subsequently, Example 12
A charge transport layer was formed in exactly the same manner as in Example 1 to produce an electrophotographic photosensitive member.

Example 16 In Example 15, the charge transport material was changed to Compound No. 29
An electrophotographic photoreceptor was produced in exactly the same manner as in Example 15, except that the composition was changed to.

Example 17 In Example 15, the charge transport material was changed to Compound No. 30
An electrophotographic photoreceptor was produced in exactly the same manner as in Example 15, except that the composition was changed to.

Comparative Example 1 An electrophotographic photosensitive member was produced in the same manner as in Example 1, except that the charge transporting material was changed to a compound represented by the following general formula (IV).

[0045]

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Comparative Example 2 An electrophotographic photosensitive member was produced in the same manner as in Example 2 except that the charge generating substance was changed to the compound represented by the general formula (II).

Comparative Example 3 An electrophotographic photoreceptor was produced in the same manner as in Example 9 except that the charge transporting material was changed to the compound represented by the general formula (IV).

Comparative Example 4 In Example 13, the charge transporting substance was replaced by the following general formula (V)
An electrophotographic photoreceptor was produced in exactly the same manner as in Example 13 except that the compound represented by the following formula (Ricoh) was used.

[0049]

Embedded image

Comparative Example 5 An electrophotographic photoreceptor was prepared in the same manner as in Example 4 except that the charge transport material was changed to a compound represented by the following formula (VI) (manufactured by Ricoh Company). Produced.

[0051]

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<Evaluation> The electrophotographic photosensitive member produced in this manner was attached to a reversal developing type RIFAX BL100, and an exhaust fan was closed to perform a running test of about 5,000 sheets.

(1) Thickness of a character was obtained by printing a thin line having a width of 0.2 mm before and after running, measuring the width of the thin line before and after running using an optical microscope, and obtaining the rate of change. Examples 1 to 8, Comparative Example 1, Comparative Example 5
The electrophotographic photoreceptor was evaluated by changing the semiconductor laser as the light source of RIFAXBL100 to the one having an oscillation wavelength of 635 nm.

(2) Image blur was caused by leaving the above-mentioned electrophotographic photosensitive member at an ozone concentration of 5 ppm for 3 days using an ozone tester (DY-1250H; manufactured by DIREC).
A test pattern was printed on the above-mentioned RIFAX BL100, and image blur was examined.

(3) The oxygen permeability coefficient of the photosensitive layer was measured by applying a charge transport layer coating solution of the above photoreceptor onto a seamless nickel belt having a diameter of 60 mm and drying it to form a coating film having a thickness of 20 μm.
This coating film was peeled off to obtain a sample. The oxygen permeability of this sample was measured using a differential pressure gas tester Model MC-C3 (manufactured by Toyo Seiki Co., Ltd.) in accordance with the gas permeability test method JIS K-7126A method. The value obtained by multiplying the oxygen permeability by the film thickness was determined as the oxygen permeability coefficient. Table 3 shows the results.

[0056]

[Table 3] Note) ◎ …… No image blur ○ …… Slight image blur △ …… Partial image blur × …… Overall image blur

[0057]

According to the electrophotographic photoreceptor of the present invention, the charge generation layer contains at least the charge generation substance represented by the general formula (I), and the oxygen transport coefficient of the charge transport layer is 3 × 10 ^-11.
cm ³ · cm / cm ² · sec · cmHg or less, the charge mobility in the lateral direction at the surface of the charge transport layer and at the interface between the charge generation layer and the charge transport layer can be reduced. It is possible to prevent the occurrence of abnormal images such as fat characters in the image and blurred images.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Tatehiko Kinoshita Ricoh Co., Ltd. 1-3-6 Nakamagome, Ota-ku, Tokyo

Claims (1)

[Claims] 1. An electrophotographic photoreceptor having a charge generation layer and a charge transport layer on a support, wherein the charge generation layer contains at least a charge generation material represented by the following general formula (I). Oxygen permeability coefficient is 3 × 10 ^-11 cm ³ · cm
/ Cm ² · sec · cmHg or less. Embedded image (In the formula, R ¹ and R ² each represent an alkyl group, an alkoxy group, a halogen atom or a hydrogen atom, which may be the same or different.)