JPH07319182A - Electrophotographic photoreceptor - Google Patents

Abstract

PURPOSE:To obtain an electrophotographic org. photoreceptor having a stable photoreceptive layer having excellent wear resistance and good sensitivity by forming the photoreceptive layer to have at least one kind selected from superfine particles of cerium oxide and boron nitride in an exposed area. CONSTITUTION:This photoreceptor consists of a conductive supporting body 1 and a photoreceptive layer 2 formed on the supporting body 1. The photoreceptive layer 2 contains at least one kind selected from superfine particles of cerium oxide and boron nitride in an exposed area. The amt. of superfine particles of cerium oxide and/or boron nitride is properly determined according to the layer structure of the photoreceptor or desired characteristics of the photoreceptor, and preferably 0.1-5 pts.wt. to 100 pts.wt. of the binder resin. Since the cerium oxide and boron nitride used are fine particles and added in a dispersed state, they prevent scattering of light and enable efficient exposure. Thus, sensitivity of the photoreceptor can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoreceptor, and more particularly to an electrophotographic photoreceptor.

[0002]

2. Description of the Related Art Organic photoconductors for electrophotography using organic photoconductive materials are easy to process, low in cost, pollution-free, and have a wide variety of material selection in designing spectral characteristics. R & D is actively underway. Since the electrical and mechanical external forces such as corona charging, toner development, transfer to paper and cleaning treatment are directly applied to the surface layer of the photoreceptor, durability against them is required. Also, when the photoconductor is actually used in a copying machine, the photoconductor is surface-deteriorated by discharge products such as ozone generated from the charging device and ultraviolet rays during exposure, so resistance to these (environmental resistance) Is also required. Further, from the viewpoint of ecology and the like, it is required to extend the life of the photoconductor. Since the surface of the organic photoreceptor is composed of an organic substance, it is liable to suffer abrasion and scratches due to repeated use, but it generally does not have sufficient durability against these.

In order to solve these problems, there have been proposed photoreceptors which have been subjected to various methods. One of them is a photoreceptor containing a metal oxide such as zinc oxide or titanium oxide in the photosensitive layer, but it is not satisfactory in terms of sensitivity. Furthermore, there are photoconductors that attempted to improve sensitivity by increasing the surface area and increasing light absorption by making zinc oxide and titanium oxide into fine particles. It has an adverse effect such as oxidizing organic substances inside.

Further, the photosensitive layer containing fluorine-based particles is
JP-A-63-249152, JP-A-63-31135
No. 6 and JP-A No. 64-23259. Fluorine-based particles are said to be effective in improving wear resistance due to their good surface properties (low surface tension and low friction coefficient), but their compatibility with the binder resin is poor. As a concrete plan for improving the environmental resistance, for example, various ultraviolet absorbers have been conventionally added to the photosensitive layer in order to prevent surface deterioration due to ultraviolet rays during exposure. However, since these ultraviolet absorbers are difficult to mix with the organic substances that form the photosensitive layer, unevenness may occur and the light absorptivity (sensitivity) at the time of exposure may deteriorate, and when used in large amounts, they may interact with organic substances. There are problems such as waking up.

[0005]

The problem to be solved by the present invention is to provide an organic photoconductor for electrophotography which has excellent abrasion resistance, good sensitivity and a stable photosensitive layer.

[0006]

The present invention relates to a conductive support and a portion which is provided on the conductive support and which exposes at least one selected from the group consisting of cerium oxide ultrafine particles and boron nitride fine particles. And a photosensitive layer containing the same. The photosensitive layer may be a single layer type photosensitive layer in which a charge generating material and a charge transporting material are dispersed in a binder resin, and a charge generating layer containing the charge generating material on a conductive support and It may be a laminated type photosensitive layer in which a charge transport layer containing a charge transport material is laminated. The charge generation layer may be laminated either above or below the charge transport layer, and the charge generation layer may contain both the charge generation substance and the charge transport substance. Further, a surface protective layer may be provided on the photosensitive layer.

The use ratio of the cerium oxide ultrafine particles and / or the boron nitride fine particles can be appropriately selected according to the layer structure of the photoconductor and the desired characteristics of the photoconductor, but it is based on 100 parts by weight of the binder resin. It is preferably used in the range of 0.1 to 5 parts by weight. When cerium oxide is used in the present invention, it is preferable to use a conventionally known ultraviolet absorber together.

The above conductive support may be in the form of a sheet or a drum, and it is preferable that the support itself or the surface of the support has conductivity and has sufficient mechanical strength in use. . Specifically, aluminum,
Copper, iron, tin, platinum, gold, silver, vanadium, molybdenum,
Chromium, cadmium, titanium, nickel, palladium,
A simple metal such as indium, stainless steel, or brass, a plastic material in which the above metal is vapor-deposited or laminated, a resin material in which carbon or the like is added to impart conductivity,
Examples thereof include glass coated with aluminum iodide, tin oxide, indium oxide and the like. Among the above conductive supports, aluminum is preferable, and in particular, aluminum that has been alumite-treated from the viewpoint that aluminum grains do not exist on the surface and black spots, pinholes, etc. are prevented from occurring in copy images and the like. May be used.

Examples of the charge transport material include fluorenone compounds such as tetracyanoethylene and 2,4,7-trinitro-9-fluorenone, and nitrated compounds such as 2,4,8-trinitrothioxanthone and dinitroanthracene. , Succinic anhydride, maleic anhydride, dibromomaleic anhydride, oxadiazole compounds such as 2,5-di (4-dimethylaminophenyl) -1,3,4-oxadiazole, 9- (4-diethylamino) Styryl)
Styryl compounds such as anthracene, carbazole compounds such as polyvinylcarbazole, 1-phenyl-3-
Pyrazoline compounds such as (p-dimethylaminophenyl) pyrazoline, indole compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazozole compounds, imidazole compounds, pyrazole compounds, triazole compounds, hydrazones Examples thereof include nitrogen-containing cyclic compounds such as system compounds, condensed polycyclic compounds, organic polysilanes, stilbene compounds, triphenylmethane compounds, and arylamine compounds.

Examples of the charge generating material include selenium, selenium-tellurium, selenium-arsenic, amorphous silicon, pyrylium salts, azo pigments, disazo pigments, ansanthuron pigments, perylene pigments, phthalocyanine pigments and indigo pigments. Pigment, triphenylmethane pigment,
Slene pigment, toluidine pigment, pyrazoline pigment,
Various pigments such as quinacridone pigment can be used. The charge generating substances may be used alone or in combination of two or more.

Further, various kinds of the above-mentioned binding resin,
For example, styrene polymers, acrylic polymers, styrene-acrylic copolymers, olefin polymers such as ethylene-vinyl acetate copolymers, polyvinyl chloride, vinyl chloride-vinyl acetate copolymers, polyesters, alkyd resins. , Polyamide, polyurethane, epoxy resin, polycarbonate, polyarylate, polysulfone, diallyl phthalate resin, silicone resin, ketone resin, polyvinyl butyral resin, polyether resin, phenol resin, xylylene resin, epoxy acrylate and other photocurable resins, etc. Polymers of can be used.

In order to prevent the deterioration of the photoreceptor and reduce the change in the electrical characteristics due to light irradiation and the like, the above-mentioned photosensitive layer is made of other hindered amine compounds, hindered phenol compounds and benzotriazole compounds. It may contain an antioxidant and an ultraviolet absorber. It may also contain a singlet energy quencher such as a fluorene compound.

The single-layer type photosensitive layer of the present invention comprises a charge generating substance,
It is formed by preparing a dispersion liquid such as a charge transport material and a binding resin, applying the dispersion liquid on a conductive support, and heating to remove the solvent. Further, the charge generation layer and the charge transport layer of the laminated photosensitive layer are laminated by adjusting and applying the dispersion liquid as in the case of the single layer type. The charge generating layer of the laminated photosensitive layer may be formed of a charge generating substance by means of vapor deposition, sputtering or the like without using a binder resin.

The organic solvent used in the preparation of the above-mentioned dispersion liquid varies depending on the kind of the binder resin and the like, but is an aliphatic hydrocarbon such as n-hexane, octane and cyclohexane, and an aroma such as benzene, toluene and xylene. Group hydrocarbons, halogenated hydrocarbons such as dichloromethane, dichloroethane, carbon tetrachloride and chlorobenzene, ethers such as dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, acetone, methyl ethyl ketone, cyclohexanone, etc. Various solvents such as ketones, esters such as ethyl acetate and methyl acetate, dimethylformamide, dimethylsulfoxide, etc. are exemplified, and one kind or a mixture of two or more kinds is used. When preparing the above-mentioned dispersion liquid, a surfactant, a leveling agent, or the like may be used in combination in order to improve the dispersibility and coatability.

The dispersion is prepared by a conventional method using a ball mill, paint shaker, sand mill, attritor, ultrasonic disperser or the like. The thickness of the photosensitive layer formed as described above is 3 to 50 μm in the single layer type,
Particularly, 5 to 20 μm is preferable, and in the laminated type, the charge generation layer is about 0.1 to 5 μm, and the charge transport layer is 5 to 50 μm, particularly 1
It is preferably 0 to 40 μm.

[0016]

The cerium oxide and the boron nitride used in the present invention are fine particles (especially cerium oxide is an ultrafine particle of 1 μm or less), and since they are added in a dispersed state, they can prevent diffused reflection of light and can be exposed efficiently. The sensitivity of the photoconductor can be improved. In addition, since these substances are inactive, they prevent decomposition of organic substances in the photosensitive layer (deterioration of the photosensitive layer) and have high hardness, so they are effective in improving the abrasion resistance of the photoconductor. .

[0017]

EXAMPLES Examples 1 to 6

[0018]

[Chemical 1]

Perylene compound 10 represented by the formula (1)
390 parts of methylene chloride was added to parts by weight (hereinafter abbreviated as “part”), and the mixture was subjected to ball mill dispersion for 24 hours. On the other hand, 100 parts of bisphenol Z-type polycarbonate, 100 parts of the aromatic amine compound represented by the formula (2), and a primary particle size of 8
An arbitrary amount of 0 nm cerium oxide was dissolved in 900 parts of methylene chloride, and this solution was added to a ball mill dispersion and dispersed by a dispar mill. The dispersion liquid thus prepared is applied onto the aluminum tube 1 and then dried to a thickness of 25
A single-layer type photoreceptor having a photosensitive layer 2 having a thickness of μm was prepared.

[0020]

[Chemical 2]

Example 7 A single-layer type photoreceptor was prepared in the same manner as in Example 1 except that cerium oxide and a conventionally known ultraviolet absorber were used in combination. Examples 8 to 13 195 parts of cyclohexanone was added to 5 parts of the metal-free phthalocyanine represented by the formula (3), and ball mill dispersion was carried out for 24 hours. On the other hand, 10 parts of a solution prepared by dissolving 40 parts of polyvinyl butyral in 160 parts of cyclohexanone was added to the ball mill dispersion, and the ball mill dispersion was continued for another 24 hours. After coating the dispersion liquid thus prepared on the aluminum base tube 1, it is dried at 100 ° C. for 30 minutes to give a thickness of 0.5 μm.
m charge generation layer 3 was obtained.

[0022]

[Chemical 3]

Next, the aromatic amine compound (2) 1
00 parts, bisphenol Z type polycarbonate 100
Part, an arbitrary amount of cerium oxide having a primary particle diameter of 80 nm is dissolved in 400 parts of methylene chloride, coated on the charge generation layer 3 prepared above, and then dried at 80 ° C. for 60 minutes to form a charge transport layer having a thickness of 25 μm. Got 4. Example 14 A multilayer photoreceptor was prepared in the same manner as in Example 8 except that cerium oxide and a conventionally known ultraviolet absorber were used in combination.

Comparative Example 1 A single-layer type photoreceptor was prepared in the same manner as in Example 1, except that cerium oxide was not used. Comparative Example 2 A single-layer type photoreceptor was prepared by the same operation as in Example 1 except that polytetrafluoroethylene was used instead of cerium oxide.

Comparative Example 3 A single-layer type photoreceptor was prepared in the same manner as in Example 1 except that 10 parts of cerium oxide was used. Comparative Example 4 A laminated-type photosensitive member was produced by the same operation as in Example 8 except that cerium oxide was not used.

Comparative Example 5 A laminated type photoreceptor was prepared in the same manner as in Example 8 except that polytetrafluoroethylene was used instead of cerium oxide. Comparative Example 6 A laminated type photoreceptor was prepared by the same operation as in Example 8 except that 10 parts of cerium oxide was used.

The printing durability of the thus obtained photoreceptor was evaluated. The results are shown in Tables 1 and 2.

[0028]

[Table 1]

[0029]

[Table 2]

Examples 15 to 20 To 10 parts of the perylene compound represented by the above formula (1) was added 390 parts of methylene chloride, and ball mill dispersion was carried out for 24 hours. On the other hand, bisphenol Z type polycarbonate 10
0 part, aromatic amine compound 1 represented by the formula (2)
An arbitrary amount of 00 parts of boron nitride having a primary particle diameter of 150 nm was dissolved in 900 parts of methylene chloride, and this solution was added to a ball mill dispersion liquid and dispersed by a dispar mill.
The dispersion liquid thus prepared was applied onto the aluminum base tube 1 and dried to prepare a single-layer type photoreceptor having a photosensitive layer 2 having a thickness of 25 μm.

Examples 21 to 26 195 parts of cyclohexanone was added to 5 parts of the metal-free phthalocyanine represented by the above formula (3), and ball mill dispersion was carried out for 24 hours. On the other hand, 10 parts of a solution prepared by dissolving 40 parts of polyvinyl butyral in 160 parts of cyclohexanone was added to the ball mill dispersion, and the ball mill dispersion was continued for another 24 hours. The dispersion liquid thus prepared is applied onto the aluminum base tube 1 and then dried at 100 ° C. for 30 minutes to give a thickness of 0.5.
A charge generation layer 3 of μm was obtained.

Next, the aromatic amine compound (2) 1
00 parts, bisphenol Z type polycarbonate 100
Part, an arbitrary amount of boron nitride having a primary particle diameter of 150 nm is dissolved in 400 parts of methylene chloride, coated on the charge generation layer 3 prepared above, and then dried at 80 ° C. for 60 minutes to form a charge transport layer having a thickness of 25 μm. Got 4. Comparative Example 7 A single-layer type photoreceptor was produced by the same operation as in Example 15 except that boron nitride was not used.

Comparative Example 8 A single-layer type photoreceptor was prepared in the same manner as in Example 15, except that polytetrafluoroethylene was used instead of boron nitride. Comparative Example 9 A single-layer type photoreceptor was prepared in the same manner as in Example 15, except that 10 parts of boron nitride was used.

Comparative Example 10 A laminated type photoreceptor was prepared in the same manner as in Example 21, except that boron nitride was not used. Comparative Example 11 A multi-layer photosensitive member was produced in the same manner as in Example 21, except that polytetrafluoroethylene was used instead of boron nitride.

Comparative Example 12 A laminated type photoreceptor was prepared in the same manner as in Example 21 except that 10 parts of boron nitride was used. The printing durability of the photoreceptor thus obtained was evaluated. The results are shown in Tables 3 and 4.

[0036]

[Table 3]

[0037]

[Table 4]

As is apparent from the above results, when the fine particles of the present invention are not added to the photosensitive layer, the film thickness is greatly reduced, and these fine particles contribute significantly to the improvement of the abrasion resistance of the photosensitive layer. You can see that Further, the decrease of the surface potential and the increase of the blank sheet potential also become large, and the sensitivity of the photosensitive layer is lowered. The same can be said when polytetrafluoroethylene is used instead of the fine particles.

Further, when 10 parts of boron nitride is used, the initial sensitivity is poor because the added amount is too large, and a proper image cannot be obtained even if the exposure amount is increased. Evaluation method for printing 80,000 sheets : Equipment used: DC-2556 remodeling machine manufactured by Mita Kogyo (a) Initial setting The surface potential of the photoconductor is set to about 800 V, and a proper image is obtained on each photoconductor. Adjust the exposure and set the initial blank sheet potential. (B) Evaluation of decrease in sensitivity After printing 80,000 sheets, changes in surface potential are measured. Further, the exposure is performed at the initially set exposure amount, and the change in the initially set blank paper potential is measured to evaluate the sensitivity decrease.

[0040]

According to the organic photoreceptor of the present invention, it is possible to obtain a stable photoreceptor having excellent abrasion resistance and good sensitivity.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view showing a part of a single-layer type photosensitive layer.

FIG. 2 is a schematic vertical sectional view showing a part of a multi-layer type photosensitive layer.

[Explanation of symbols]

 1 Aluminum tube 2 Photosensitive layer 3 Charge generation layer 4 Charge transport layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hirosuke Sakai 1-2-2 Tamatsukuri, Chuo-ku, Osaka Mita Kogyo Co., Ltd. (72) Tomoki Tanaka 1-2-2 Tamatsukuri, Chuo-ku, Osaka Mita Within Kogyo Co., Ltd. (72) Inventor Ayako Sugase 1-22 Tamagaku, Chuo-ku, Osaka Mita Kogyo Co., Ltd.

Claims (1)

[Claims] 1. A conductive support, and a photosensitive layer which is provided on the conductive support and includes at least one kind selected from the group consisting of ultrafine particles of cerium oxide and fine particles of boron nitride. Electrophotographic photoreceptor.