JPH05173338A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain a high durability sensitive body for positive charge ensuring high photoelectric and mechanical shock resistance and high wear resistance for the photosensitive layer and not causing the blurring of an image, the lowering of image density, fogging, etc., during repeated image formation. CONSTITUTION:This electrophotographic sensitive body contains at least one kind of thermosetting silicone resin and at least one kind of polyvinyl acetal resin in the electric charge generating layer 3 as the surface layer and a polycarbonate-based resin binder in the electric charge transferring layer 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positive charging electrophotographic photoreceptor having a charge transport layer and a charge generating layer in this order on a conductive support.

[0002]

2. Description of the Related Art Heretofore, in order to form an image by an electrophotographic method, a so-called Carlson method is generally used.
An electrostatic latent image is formed by uniformly charging and imagewise exposing the surface of the photoconductor, and the latent image is developed to form a toner image, which is transferred and fixed on a transfer material to form an image. Be seen.

On the other hand, the photosensitive member after transfer is subjected to static elimination by a static eliminator, rubbing a cleaning member such as a cleaning blade or a cleaning brush to remove residual toner, and is repeatedly used for a long period of time.

Therefore, as an electrophotographic photosensitive member, of course, electrophotographic characteristics such as good charging characteristics and sensitivity and small dark decay, as well as printing durability after repeated use, abrasion resistance,
It is also required to have good physical properties such as humidity resistance, and resistance (environmental resistance) to ozone generated during corona discharge and ultraviolet rays during exposure.

Conventionally, selenium has been used as an electrophotographic photoreceptor.
Inorganic photoreceptors having a photosensitive layer containing an inorganic photoconductive substance such as zinc oxide and cadmium sulfide as a main component are widely used.

On the other hand, the utilization of various organic photoconductive substances as materials for the photosensitive layer of an electrophotographic photoreceptor has been actively developed and studied in recent years.

For example, Japanese Patent Publication No. 50-10496 describes an organic photoreceptor having a photosensitive layer containing poly-N-vinylcarbazole and 2,4,7-trinitro-9-fluorenone. However, this photoreceptor is not always satisfactory in sensitivity and durability.

In order to improve such drawbacks, an organic photoreceptor having high sensitivity and high durability is developed by separately sharing a charge generation function and a charge transport function in a photosensitive layer. Attempts are being made. In this kind of function-separated type electrophotographic photoreceptor,
Since a substance exhibiting each function can be selected from a wide range, it is possible to relatively easily manufacture an electrophotographic photoreceptor having arbitrary characteristics. According to such an organic electrophotographic photoreceptor, since the photosensitive layer can be formed by coating, the manufacturing cost is low, pollution and environmental pollution can be prevented, and various shapes (sheet shape, etc.) can be easily processed.

However, the organic electrophotographic photoreceptor has the following drawbacks, and there is a strong demand for solving these drawbacks.

(A) For example, since a layer is formed by binding a low molecular weight organic compound with a high molecular weight organic resin (binder), the mechanical strength is not always sufficient, and when the photoreceptor is repeatedly used, The surface of the photoconductor is scratched or worn by rubbing of the developing blade.

(B) The photoconductor is mainly used for negative charging. As described in JP-A-60-247647, a thin charge generating layer is provided on a support and a relatively thick charge is formed on the support. It is configured to have a transport layer.

The reason for this is that when negatively charged, a hole transporting material can be used, which is advantageous in terms of high sensitivity and the like, while an electron transporting material has excellent characteristics. This is because there are very few substances that are toxic or carcinogenic and cannot be used.

In addition, when the photoconductor is negatively charged by using the hole transporting material, a large amount of ozone is generated at the time of charging to deteriorate the environmental conditions. Further, the ozone and other ionic substances are adsorbed on the surface of the photoconductor to deteriorate the material, and repeated use causes a decrease in potential, an increase in residual potential, a decrease in sensitivity, a decrease in image quality, and a decrease in life of the photoconductor. ..

Therefore, research and development have been carried out on a positive charging photoreceptor having a charge transporting layer containing a hole transporting charge transporting substance on a support and a charge generating layer as a surface layer thereon. .. According to the photoconductor for positive charging, generation of ozone during charging is extremely small, which is advantageous in environmental hygiene.

However, the charge generation layer provided as the surface layer contains the charge generation substance in the form of fine particles at a high density,
There is a problem that it is easily worn and deteriorated due to mechanical shock, changes in temperature and humidity conditions, and the like.

Then, for example, JP-A-2-189550, JP-A-2-189551, JP-A-2-236555, and JP-A-2-23
6556, and JP-A-2-240655, etc., as a binder resin of the surface layer of the photoreceptor, various substituted polycarbonate, cyclic polycarbonate containing a central carbon atom, polycarbonate having a silicon atom as a central atom, polycarbonate-polycarbonate Various polycarbonates such as siloxane block copolymers have been proposed.

It has been pointed out that these polycarbonates are excellent in dispersibility of a charge generating substance and film characteristics, are resistant to photoelectric fatigue deterioration due to repeated charging exposure, and are excellent in mechanical abrasion resistance.

However, in recent copying machines and the like,
High speed, high durability, and high image quality are required, and therefore, further improvement in film strength of the surface layer of the photoconductor has been demanded.

By the way, one of the measures for the film strength of the surface layer of the photoconductor is
For example, in Japanese Patent Laid-Open No. 61-117558, for example, SiO ₂ , CrO ₂ , Al ₂ O ₃ , SiC, TiO ₂ , ZnO as a reinforcing agent in the photosensitive layer is used.
It has been proposed to incorporate inorganic compound particles such as

Further, JP-A-63-30850 and JP-A-64-3
Japanese Patent No. 5448 describes a technique of incorporating a solid lubricant and silicone oil into the surface layer of a photoreceptor. Further, JP-A-2-189550 and JP-A-2-189551 propose techniques for incorporating a polycarbonate resin and a fluororesin or fluororesin particles into the surface layer of a photoreceptor.

However, an organic photoreceptor for positive charging, which contains an organic photoconductive pigment in a high density and has a thin charge generating layer as a surface layer, achieves the high durability and high image quality required recently. Insufficient to do so, image defects such as image blur and image unevenness are unavoidable due to abrasion and damage of the photosensitive layer surface during repeated image formation, and further improvement of film properties is desired. It is rare.

[0022]

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic photosensitive member for positive charging which is free from abrasion of the surface due to friction, scratches, image blurring and the like and which provides a high quality copied image.

Another object of the present invention is to provide a highly durable electrophotographic photosensitive member which has good cleaning properties and does not cause image deterioration due to toner filming on the surface layer of the photosensitive member.

Still another object of the present invention is to prevent the occurrence of fogging due to the increase of the residual potential during the repeated image formation, and to obtain a high density and clear image quality stably, and an electrophotographic photosensitive member for positive charging. To provide.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to an electrophotographic photosensitive member comprising a conductive support, and a charge transport layer and a charge generation layer laminated in this order, wherein a binder resin containing a polycarbonate resin as a main component is contained in the charge transport layer. And at least one thermosetting silicone resin and at least one polyvinyl acetal resin are contained in the charge generation layer.

The electrophotographic photoreceptor of the present invention will be described in detail below.

The drawings are schematic sectional views for explaining the layer structure of the electrophotographic photosensitive member of the present invention. In FIG.
Reference numeral 1 is a conductive support, 2 is a charge transport layer, and 3 is a charge generation layer.

The thermosetting silicone resin contained in the charge generation layer of the present invention includes SiX ₄ , RSiX ₃ , RSiX ₂ and R ₃ Si.
A silane having 1 to 4 functional units having a structure of X (R = organic group, X = functional group), which is crosslinked with a silane having 3 or 4 functional groups, is preferably used.

Examples of the polyvinyl acetal resin contained in the charge generation layer of the present invention include polyvinyl butyral, polyvinyl formal, polyvinyl acetoacetal, polyvinyl propyl acetal and the like.

Among them, polyvinyl butyral resin is preferably used.

Further, the charge transport green layer 2 of the present invention contains at least one of polycarbonate as a binder resin.

As the charge generating substance contained in the charge generating layer, the following organic photoconductive materials which absorb visible light and generate free charges can be used.

(1) Azo pigments such as monoazo pigments, polyazo pigments, metal complex salt azo pigments, pyrazolone azo pigments, stilbene azo pigments and thiazole azo pigments (2) Perylene pigments such as perylene anhydride and perylene imide ( 3) Anthraquinone-based or polycyclic quinone-based pigments such as anthraquinone derivatives, anthanthrone derivatives, dibenzpyrenequinone derivatives, pyranthrone derivatives, violanthrone derivatives and isobiolanthrone derivatives (4) Indigooid pigments such as indigo derivatives and thioindigo derivatives (4) 5) Phthalocyanine pigments such as metal phthalocyanine and metal-free phthalocyanine (6) Carbonium pigments such as diphenylmethane pigment, triphenylmethane pigment, xanthene pigment and acridine pigment (7) Azine pigment, oxazine pigment And thiazine pigments and other quinoneimine pigments (8) Cyanine pigments and azomethine pigments and other methine pigments (9) Quinoline pigments (10) Nitro pigments (11) Nitroso pigments (12) Benzoquinone and naphthoquinone pigments (13) Naphthalimide pigments (14) Perinone pigments such as bisbenzimidazole derivatives.

Among them, the pigments preferably used in the present invention include polycyclic quinone pigments represented by the following general formula (1), (2) or (3).

[0035]

[Chemical 1]

[In the above formulas, X is a halogen atom,
It represents a nitro group, a cyano group, an acyl group or a carboxyl group, n is an integer of 0 to 4 and m is an integer of 0 to 6. Specific examples of the polycyclic quinone pigment are disclosed in JP-A-60
-172044, pages 24-26. Other usable charge generating substances include bisazo compounds represented by the following general formula (4).

[0037]

[Chemical 2]

[However, in this general formula (4), X ₁ , X ₂
Represents a hydrogen atom or a halogen atom.

A ₁ :

[0040]

[Chemical 3]

(X is a hydroxy group, or --N (R ² ) (R ³ ), or --NHSO ₂ --R ⁴ , where R ² and R ³ are a hydrogen atom, a substituted or unsubstituted alkyl group, R ⁴ is a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group> Y is
Hydrogen atom, halogen atom, substituted or unsubstituted alkyl group,
Alkoxy group, carboxyl group, sulfo group, substituted or unsubstituted carbamoyl group or substituted or unsubstituted sulfamoyl group, provided that when m is 2 or more, the groups may be different from each other. ) Z is an atomic group necessary for constituting a substituted or unsubstituted carbocyclic aromatic ring or a substituted or unsubstituted heterocyclic aromatic ring, R
¹ is a hydrogen atom, a substituted or unsubstituted amino group, a substituted or unsubstituted carbamoyl group, a carboxyl group or an ester group thereof, A ₂ is a substituted or unsubstituted aryl group, n is an integer of 1 or 2, m is an integer of 0-4. Specific examples of the bisazo compound represented by the general formula (4) are described, for example, in JP-A 1-200361 on pages 3 to 10.

As another charge generating substance, a bisazo compound represented by the following general formula (5) can be used.

[0043]

[Chemical 4]

(However, in this general formula, A ₃ is

[0045]

[Chemical 5]

Z is an atomic group necessary for constituting a substituted or unsubstituted aromatic carbocycle or a substituted or unsubstituted aromatic heterocycle, Y: a hydrogen atom, a hydroxyl group, a carboxyl group or an ester group thereof. , Sulfo group, substituted or unsubstituted carbamoyl group, substituted or unsubstituted sulfamoyl group, R ⁵ : hydrogen atom, substituted or unsubstituted alkyl group, substituted or unsubstituted amino group, substituted or unsubstituted carbamoyl group , A carboxyl group or an ester group thereof, or a cyano group, Ar ³ : a substituted or unsubstituted aryl group, R ⁶ : a substituted or unsubstituted alkyl group, a substituted or unsubstituted aralkyl group, or a substituted or unsubstituted aryl group Represents. ) Specific examples of the bisazo compound represented by the general formula (5) are described in JP-A 1-219841 page 2-4.

The charge-generating substance as described above is dispersed and contained in the silicone resin and the polyvinyl acetal resin in the form of fine particles having a diameter of 0.1 to 1 μm to form a layer.

The charge transport material contained in the charge transport layer of the present invention contains at least one selected from the following group.

Examples of the charge transport material include oxazole derivatives, oxadiazole derivatives, thiazole derivatives, thiadiazole derivatives, triazole derivatives, imidazole derivatives, imidazolone derivatives, imidazolidine derivatives,
Bisimidazolidine derivative, styryl compound, hydrazine compound, pyrazoline derivative, oxazolone derivative, benzothiazole derivative, benzimidazole derivative, quinazoline derivative, benzofuran derivative, acridine derivative, phenazine derivative, aminostilbene derivative, poly
-N-vinylcarbazole, poly-1-vinylpyrene, poly-9
-Vinyl anthracene and the like.

Specific examples thereof include styryl compounds represented by the following general formula (6) or (7).

[0051]

[Chemical 6]

In the above general formula, R ⁷ and R ⁸ represent the following two groups which are substituted or unsubstituted; an alkyl group and an aryl group, the substituent being an alkyl group, an alkoxy group, a substituted amino group, a hydroxyl group or a halogen. Atoms and aryl groups.

Ar ⁴ and Ar ⁵ represent a substituted or unsubstituted aryl group, and examples of the substituent include an alkyl group, an alkoxy group, a substituted amino group, a hydroxyl group, a halogen atom and an aryl group.

R ⁹ and R ¹⁰ represent a substituted or unsubstituted aryl group or a hydrogen atom, and examples of the substituent include an alkyl group, an alkoxy group, a substituted amino group, a hydroxyl group, a halogen atom and an aryl group.

[0055]

[Chemical 7]

In the above general formula, R ¹¹ is a substituted or unsubstituted aryl group, R ¹² is a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, an alkoxy group, an amino group, a substituted amino group, a hydroxyl group, R ¹³ Is a substituted or unsubstituted aryl group, substituted,
It represents an unsubstituted heterocyclic group.

Further, a hydrazone compound represented by the following general formula (8), (9), (10) or (11) can be used as a carrier transporting substance.

[0058]

[Chemical 8]

In the formula, R ¹⁴ and R ¹⁵ each represent a hydrogen atom or a halogen atom, R ¹⁶ and R ¹⁷ each represent a substituted or unsubstituted aryl group, and Ar ⁶ represents a substituted or unsubstituted arylene group.

[0060]

[Chemical 9]

In the formula, R ¹⁸ is a methyl group, ethyl group, 2-hydroxyethyl group or 2-chloroethyl group, R ¹⁹ is a methyl group, ethyl group, benzyl group or phenyl group, R ²⁰ is a methyl group, ethyl group, A benzyl group or a phenyl group is shown.

[0062]

[Chemical 10]

In the formula, R ²¹ is a substituted or unsubstituted naphthyl group,
R ²² is a substituted or unsubstituted 3 group; an alkyl group, an aralkyl group or an aryl group, R ²³ is a hydrogen atom, an alkyl group or an alkoxy group, and R ²⁴ and R ²⁵ are substituted or unsubstituted 3 groups. Group: The same or different groups selected from an alkyl group, an aralkyl group and an aryl group are shown.

[0064]

[Chemical 11]

In the formula, R ²⁶ is a substituted or unsubstituted aryl group or a substituted or unsubstituted heterocyclic group, R ²⁷ is a hydrogen atom, substituted or
The following two unsubstituted groups; an alkyl group, an aryl group, Q is a hydrogen atom, a halogen atom, an alkyl group, a substituted amino group,
It represents an alkoxy group or a cyano group, and m represents an integer of 0 or 1.

As the charge transport material, the following general formula (1
The pyrazoline compound of 2) can also be used.

[0067]

[Chemical 12]

In the formula, n represents 0 or 1, R ²⁸ , R ²⁹ and R ³⁰ are substituted or unsubstituted aryl groups, R ³¹ and R ³² are hydrogen atoms, alkyl groups having 1 to 4 carbon atoms, Alternatively, it represents a substituted or unsubstituted aryl group or aralkyl group. However,
Neither R ³¹ nor R ³² is a hydrogen atom, and n is 0.
Then R ³¹ is not a hydrogen atom.

Further, the amine derivative represented by the following general formula (13) can also be used as the charge transport material.

General formula (13) Ar ⁹ --N (Ar ⁷ ) (Ar ⁸ ) In the formula, Ar ⁷ and Ar ⁸ represent a substituted or unsubstituted phenyl group,
As a substituent, a halogen atom, an alkyl group, a nitro group,
Alkoxy groups are used.

Ar ⁹ represents a substituted or unsubstituted phenyl group, naphthyl group, anthryl group, fluorenyl group or heterocyclic group, and the substituent is an alkyl group, an alkoxy group, a halogen atom, a hydroxyl group, an aryloxy group or an aryl group. , Amino group, nitro group, piperidino group, morpholino group, naphthyl group, anthryl group and substituted amino group. However,
An acyl group, an alkyl group, an aryl group, or an aralkyl group is used as a substituent of the substituted amino group.

Specific examples of the charge transport material represented by the general formulas (6) to (13) are described in JP-A-60-172044.

Polycarbonate is preferably used as the binder resin contained in the charge transport layer.

The layer structure of the photoconductor of the present invention will be described more specifically below with reference to FIG.

In the figure, the conductive support 1 may be formed of either a conductive material or an insulating material. Examples of the conductive material include metals such as stainless steel, aluminum, chromium, molybdenum, iridium, tellurium, titanium, platinum and palladium, and alloys thereof. Examples of the insulating material include a film or sheet of synthetic resin such as polyester, polyethylene, polycarbonate, cellulose acetate, polypropylene, polyvinyl chloride, polyvinylidene chloride, polystyrene and polyamide, glass, ceramic, paper and the like. When an insulating material is used, its surface is preferably subjected to a conductive treatment. In particular,
For example, in the case of glass, conductive treatment is performed with indium oxide, tin oxide, etc., and in the case of synthetic resin film such as polyester film, aluminum, silver, lead, nickel,
Conductive treatment of metal such as gold, chromium, molybdenum, iridium, niobium, tantalum, vanadium, titanium, platinum by vacuum vapor deposition, electron beam vapor deposition, sputtering or the like or by laminating with the above metal. ..

Then, 20 to 200 parts by weight, preferably 30 to 100 parts by weight, of the above charge transport material is mixed with 100 parts by weight of the polycarbonate on the conductive support 1,
The charge transport layer 2 having a thickness of 5 to 50 μm is formed. Then, the charge generation layer 3 containing 5 to 500 parts by weight, preferably 50 to 300 parts by weight of the charge generation substance dispersed in 100 parts by weight of the binder resin is laminated on the charge transport layer 2 to a thickness of 0.05 to 10 μm,
The photoconductor of the present invention is obtained.

In the photoconductor of the present invention, when the amount of the charge generating substance in the charge generating layer is less than 5 parts by weight with respect to 100 parts by weight of the binder resin, the light absorption is insufficient and the sensitivity is lowered to 500 parts by weight. If it exceeds the range, the film becomes brittle and the mechanical strength is reduced.

When the amount of the charge transport material is less than 20 parts by weight with respect to 100 parts by weight of the binder resin, charge injection and transport are poor and the sensitivity is lowered, and when it exceeds 200 parts by weight, the film becomes brittle and mechanical strength is increased. Is reduced.

Hereinafter, the present invention will be described in detail with reference to Examples, but the embodiments of the present invention are not limited thereto.

[0080]

【Example】

Example 1 An aluminum drum having an outer diameter of 80 mm and a length of 355.5 mm was prepared, a 20 μm-thick electric charge was provided by a dipping method using the following coating solution, and dried at 90 ° C. for 30 minutes.

<Coating Liquid for Forming Charge Transport Layer> 1,2-Dichloroethane 1000 ml Polycarbonate (TS-2020, Teijin Chemicals Ltd.) 200 g Polyester (Vylon 200, Toyobo Co., Ltd.) 5 g Exemplified Compound [I] 150 g Antioxidant ( Sumitomo Chemical Co., Ltd. Sumilizer BHT 5g Silicone oil (Shin-Etsu Chemical Co., Ltd. KF-54) 0.1g Next, a 2 μm-thick charge generation layer was formed on the charge transport layer by the circular slide hopper method using the following coating liquid. , 90
It was dried at ℃ for 30 minutes.

<Coating Liquid for Forming Charge Generation Layer> Silicone resin (KP-85, Shin-Etsu Chemical Co., Ltd.) 100 ml Polyvinyl butyral resin (S-REC BX-1, Sekisui Chemical Co., Ltd.) 2 g Exemplified compound [II] 30 g Antioxidant ( Sumitomo Chemical Co., Ltd. Sumilizer BHT 5g The photoconductor thus obtained was manufactured by Konica Corporation U-Bix3.
It was mounted on a modified 035 copying machine, and a real copying test of 10,000 copies was conducted to evaluate changes in the surface potential of the photoconductor and evaluation of the copied image.

Comparative Example 1 A photosensitive member was prepared and evaluated in the same manner as in Example 1 except that the polyvinyl butyral resin was omitted from the coating solution for forming the surface protective layer of Example 1.

Comparative Example 2 The procedure of Example 1 was repeated except that the charge generation layer type coating solution of Example 1 was replaced with 100 ml of 1,2 dichloroethane as a solvent and 30 g of polyvinyl butyral resin except the silicone resin. A photoconductor was prepared and evaluated.

Comparative Example 3 A photoreceptor was prepared and evaluated in the same manner as in Example 1 except that polyvinyl butyral resin was used instead of the polycarbonate resin in the charge transport layer coating liquid of Example 1.

The evaluation results are shown in Table 1 below. As the developer in this example, a developer for U-Bix5070 manufactured by Konica Corporation was used.

[0087]

[Table 1]

As can be seen from the results in Table 1, the present invention provides a good image in which the amount of abrasion of the photoconductor is small, the electrostatic characteristics of the photoconductor are not deteriorated, and the fog does not occur during the repeated image formation. You can see that.

The structural formulas of the exemplified compounds [I] and [II] used in the examples are shown below.

[0090]

[Chemical 13]

[0091]

The photoconductor of the present invention is a photoconductor for positive charging having the charge transport layer as the lower layer and the charge generation layer as the upper layer, so that it is possible to prevent pollution such as ozone generation, and At least one type of thermosetting silicone resin and polyvinyl acetal resin are contained in each, and by containing a binder resin containing polycarbonate as a main component in the charge transport layer, the photoconductor is resistant to photoelectric deterioration and mechanical abrasion. It can be endowed with high durability properties and therefore also
When the photoreceptor is used for a long period of time, it is possible to obtain effects such as stable image quality.

[Brief description of drawings]

FIG. 1 is a sectional view showing a layer structure of a photoreceptor of the present invention.

[Explanation of symbols]

 1 Conductive Support 2 Charge Transport Layer 3 Charge Generation Layer

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[Procedure amendment]

[Submission date] February 25, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0083

[Correction method] Change

[Correction content]

Comparative Example 1 A photoconductor was prepared and evaluated in the same manner as in Example 1 except that the polyvinyl butyral resin was removed from the charge generation layer forming coating liquid of Example 1.

Claims (1)

[Claims] 1. An electrophotographic photoreceptor comprising a charge transport layer and a charge generating layer laminated in this order on a conductive support, wherein the charge transport layer contains a binder resin containing a polycarbonate resin as a main component. An electrophotographic photosensitive member comprising the charge generation layer containing at least one thermosetting silicone resin and at least one polyvinyl acetal resin.