JP2003098713A - Electrophotographic photoreceptor, image forming apparatus using the same and process unit for image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor which has high durability and makes good images obtainable in spite of repetitive use. SOLUTION: In the electrophotographic photoreceptor provided with at least a photosensitive layer on a conductive base, the uppermost surface layer of the electrophotographic photoreceptor contains at least inorganic fillers and a binder resin and the inorganic fillers are homogeneous single crystal particles of α-alumina not internally having crystal seeds.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention has high durability,
The present invention also relates to an electrophotographic photosensitive member that achieves high image quality over a long period of time. Further, the present invention relates to an image forming method, an image forming apparatus, and a process unit for the image forming apparatus using the photoconductors.

[0002]

2. Description of the Related Art An electrophotographic method using an electrophotographic photosensitive member applied to a copying machine, a facsimile machine, a laser printer, a direct digital plate making machine, etc. is a process of at least charging, image exposure and development of the electrophotographic photosensitive member. After that, the toner image is transferred to the image carrier (transfer paper), fixed, and the surface of the electrophotographic photosensitive member is cleaned.

The basic characteristics required of the electrophotographic photosensitive member in this electrophotographic method are that it can be charged to an appropriate potential in a dark place, that the dissipation of electric charge is small in a dark place, and the electric charge can be rapidly applied by light irradiation. It can be dissipated. In addition to these characteristics, long-term reliability such as image quality characteristics, low pollution, low cost, etc. are required.

Conventionally, as a photoconductor used in the electrophotographic system, a photoconductor having a selenium or selenium alloy as a main component is provided on a conductive support, or an inorganic light such as zinc oxide or cadmium sulfide. Those in which a conductive material is dispersed in a binder, and those using an amorphous silicon-based material are generally known, but in recent years, low cost, high degree of freedom in designing a photoconductor, Organic photoconductors have come to be widely used because of their pollution-free property.

For organic electrophotographic photoreceptors, a photoconductive resin typified by polyvinylcarbazole (PVK), P
VK-TNF (2,4,7-trinitrofluorenone)
Known as a charge transfer complex type, a phthalocyanine-binder-type pigment dispersion type, and a function-separated type photoconductor in which a charge-generating substance and a charge-transporting substance are used in combination. The photoconductor has attracted attention because it is excellent in various properties such as sensitivity, durability, and stability.

The mechanism of formation of an electrostatic latent image in this function-separated type photoconductor is that when the photoconductor is charged and then irradiated with light, the light passes through a transparent charge transport layer and is caused by a charge generating substance in the charge generating layer. The charge-generating substance that has been absorbed and absorbs light generates charge carriers, which are injected into the charge-transporting layer and move in the charge-transporting layer along the electric field generated by charging, so that the charge on the surface of the photoconductor is removed. By neutralizing, an electrostatic latent image is formed. In the function-separated type photoreceptor, it is known to use a charge transporting substance having a high mobility and having an absorption mainly in the ultraviolet region, and a charge generating substance having a high quantum efficiency and having an absorption mainly in the visible region. And is useful.

However, most of the charge-transporting substances of the organic electrophotographic photosensitive member used in the electrophotographic method have been developed as low molecular weight compounds, and the low molecular weight compounds alone have no film-forming property, and thus are usually inactive. Used by being dispersed and mixed in a polymer. However, the charge transport layer consisting of a low molecular weight charge transport material and an inert polymer is generally soft, and when repeatedly used in the electrophotographic process, the film is scraped by the mechanical load on the photoreceptor surface due to the developing system and the cleaning system. One of the disadvantages is the low wear resistance, which is likely to occur. In fact, abrasion of the film of the photoconductor may have adverse effects such as deterioration of sensitivity and deterioration of chargeability, and an abnormal image such as a decrease in image density and background stain may occur, which may lead to the life of the photoconductor.

In recent years, due to the downsizing of the image forming apparatus, the diameter of the photoconductor has been reduced, and the speeding up of the machine and the movement of maintenance-free operation have been added to this, and the durability of the photoconductor has been earnestly desired. To increase the durability of the photoconductor, improving the abrasion resistance is the first issue. As for this technology,
Using a curable binder in the surface layer (JP-A-56-
No. 48637), an improved photoreceptor binder resin (JP-A-5-216250), a polymer charge transport material (JP-A 64-1728), and an inorganic filler in the surface layer. And the like (Japanese Patent Application Laid-Open No. 4-281461) and the like.

Among these techniques, the one using the curable binder has poor compatibility with the charge-transporting substance and impurities such as a polymerization initiator and unreacted residues increase the potential at the exposed portion to increase the image density. A drop occurs. The improved binder resin does not exhibit a marked improvement in wear resistance due to the composition ratio of the low molecular weight charge transport material. In addition, although the one using the polymer type charge transporting substance can improve abrasion resistance to some extent, its durability is not sufficient, and it is difficult to polymerize and purify the material, and it is difficult to obtain a highly pure substance. Further, there is a problem in production such that the coating liquid has a high viscosity. On the other hand, the one in which the inorganic filler is dispersed exhibits higher abrasion resistance and the repeated electric characteristics are better than the photoreceptor in which the ordinary low-molecular-weight charge transport material is dispersed in the inactive polymer. To be done.

However, the photoconductor in which the inorganic filler is dispersed in this surface layer also has some drawbacks. For example, there is a drawback that image deletion occurs in repeated use. The reason for this is that the dispersion of the inorganic filler improves the abrasion resistance, and the renewal due to the abrasion of the photoconductor surface cannot catch up with the permeation of the oxidizing gas such as ozone and NOx generated from the charger. The reason is that filming of toner or paper powder occurs on the surface irregularities caused by the dispersion of the inorganic filler, and the oxidizing gas is adsorbed on the filming. This image flow occurs violently when silica having acidic properties or tin oxide having low resistance is used as the inorganic filler, and conversely, when titanium oxide which is basic or alumina having high resistance is used, it is mild. Is.

On the other hand, when titanium oxide or alumina is used as the inorganic filler, contrary to the image flow, the potential of the exposed portion becomes high and an abnormal image such as insufficient image density or background stain occurs. This is due to the material of titanium oxide or alumina described above, and is caused by the charge trap on the surface of the filler. Therefore, when silica or tin oxide is used, the potential of the exposed area does not rise significantly.

Another drawback is that the addition of an inorganic filler to the surface layer reduces the linearity of light during exposure,
Image resolution and gradation deteriorate. This phenomenon is remarkable when an inorganic filler having a high whiteness, such as titanium oxide or alumina, is used.

Further, there arises a problem due to the shape and particle size distribution of the filler used. For example, when a pulverization method is used as a method for producing fine particles, the cleaning blade may be chipped due to protrusions on the surface of the photoconductor due to the filler because of a sharp crushed shape, resulting in streak-shaped cleaning failure. Further, when a filler containing a large amount of fine powder is used, uneven wear caused by the difference in particle size may occur, and the density and the background image may be abnormal due to variations in sensitivity and chargeability.

In addition, in order to obtain a highly durable electrophotographic photoreceptor, (i) the surface protective layer contains a curable resin and one or more materials selected from glass materials and ceramic materials having a Mohs hardness of 3 or more. (JP-A-10-78673), (ii) Hydrophobic silica or hydrophobic silicone of 0.1 to 10 μm is contained in the charge transport layer (JP-A-8-78).
No. 146626), (iii) fine particles of vapor-phase synthetic silica are contained in the charge transport layer (JP-A-7-261417).
Japanese Patent Laid-Open Publication No. 2004-242242, etc., but these tend to cause the above cleaning failure and uneven wear.

In any case, some of these drawbacks in the conventional photoconductor in which the inorganic filler is dispersed are caused by the inorganic filler material used, but they are good enough to satisfy all the problems. At present, no inorganic filler has been found.

[0016]

SUMMARY OF THE INVENTION An object of the present invention is to provide a high-performance and highly reliable electrophotographic photoreceptor having high durability and capable of continuously obtaining a good image even after repeated use. To do. Another object of the present invention is to provide a highly reliable image forming apparatus and a process unit for the image forming apparatus, which is small in size and capable of high-speed printing by using the electrophotographic photosensitive member.

[0017]

As a result of intensive studies, the inventors of the present invention have found that the outermost surface layer of an electrophotographic photosensitive member contains at least an inorganic filler and a binder resin. The present invention has been accomplished by discovering that the above object can be achieved by using single crystal particles of α-alumina having no crystal seed. That is, the present invention comprises the following modes (1) to (7).

(1) In an electrophotographic photoreceptor having at least a photosensitive layer provided on a conductive support, the outermost surface layer of the electrophotographic photoreceptor contains at least an inorganic filler and a binder resin, and An electrophotographic photoreceptor, wherein the filler is a single crystal particle of α-alumina which is homogeneous and has no crystal seed inside.

(2) The α-alumina particles are fired in a transitional alumina raw material or an alumina raw material which becomes a transitional alumina by heat treatment in an atmosphere gas containing a hydrogen halide gas or an atmosphere gas into which a halogen gas and steam are introduced. The electrophotographic photosensitive member according to (1) above, which is manufactured by

(3) The electrophotographic photosensitive member according to the above (1) or (2), wherein the α-alumina particles have a center particle size of 0.1 to 1 μm.

(4) The α-alumina particles have a sodium content of 10 ppm or less in terms of Na ₂ O and a purity of 99.95% by weight or more (1) to (). The electrophotographic photosensitive member according to any one of 3).

(5) The electrophotographic photoreceptor according to any one of the above (1) to (4), wherein the outermost surface layer contains a polycarboxylic acid compound.

(6) An image forming apparatus having a charging means, an exposing means, a developing means and a transferring means in addition to the electrophotographic photosensitive member according to any one of the above (1) to (5).

(7) At least one selected from the group consisting of a charging means, a developing means, a transfer means, a cleaning means and a charge eliminating means in addition to the electrophotographic photosensitive member according to any one of the above (1) to (5). A process unit for an image forming device that integrates two means and is removable.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below. As in the present invention, in the electrophotographic photoreceptor in which the outermost surface layer contains at least an inorganic filler and a binder resin, single crystal particles of α-alumina that are homogeneous and do not have crystal seeds inside are used as the inorganic filler. Therefore, for any reason, it has high durability, does not cause image deletion during repeated use, has high resolution and gradation, and maintains good images without background stains and image density reduction. It has not been clarified at present whether the effect of being obtained can be obtained, but the following reasons are considered. Incidentally, it is a well-known fact that the electrophotographic photosensitive member containing an inorganic filler in the outermost surface layer has very high abrasion resistance as described in detail in the description of the conventional art. The reason why the photoreceptor of the present invention is particularly effective will be described with respect to the problems of the photoreceptor having a filler in the outermost surface layer.

The electrophotographic photosensitive member of the present invention suppresses the occurrence of image deletion during repeated use. The reason for this is that the inorganic filler contained in the outermost surface layer uses basic and high-resistance α-alumina, which is different from acidic silica and low-resistance tin oxide. It is considered that this is because the single crystal particles have few active groups that adsorb the oxidizing gas generated from. Not only the material of the filler but also the surface area of the particles have a great influence on the image flow due to the adsorption action of the oxidizing gas.

The α-alumina single crystal particles used in the present invention are preferably transition alumina as a raw material or an alumina raw material to be transition alumina by heat treatment in an atmosphere gas containing a hydrogen halide gas or a halogen gas and steam. Since the filler is produced by firing in an atmosphere gas in which is introduced, the filler has a narrow filler particle size distribution and a very small proportion of fine powder as compared with the pulverization method. This has the effect of suppressing the occurrence of image deletion without increasing the surface area of the filler.

Further, the electrophotographic photosensitive member of the present invention has a slight increase in the potential at the exposed portion, which is observed in the photosensitive member in which the outermost surface layer contains a basic filler or a high resistance filler. The reason for this is that in the present invention, single crystal particles of α-alumina are used, so that the number of active groups that trap charges is small on the particle surface, and the use of the above-mentioned manufacturing method results in a very small proportion of fine powder. It is also affected by the fact that it can be reduced. Furthermore, it is important that the sodium content of the α-alumina single crystal particles used in the present invention is 10 ppm or less in terms of Na ₂ O, and more preferably the purity is 99.95% by weight or more, Alkali ions such as sodium ions act as a trap for electric charges and cause an increase in the potential of the exposed area.

Further, in the electrophotographic photosensitive member of the present invention, almost no deterioration in image resolution and gradation is observed when a filler having high whiteness such as alumina or titanium oxide is used for the outermost surface layer. Unlike a normal photoconductor, a photoconductor containing an inorganic filler in the outermost layer causes incident light to be reflected on the surface of the filler, and to be dissipated due to absorption and scattering inside the filler. Of these, reflection is relative to the medium through which light propagates and enters and the difference in the refractive index inherent to the filler material, and is therefore determined by the selection of the filler material. The refractive index of the photoreceptor is 1.6 to 1.7 in the case of the charge transport layer, and is slightly smaller than that in the case of the protective layer, and is in the range of 1.5 to 1.6. The refractive index of the inorganic filler is 1.76 for alumina, 1.55 for silica, 2.71 for titanium oxide. The difference in the refractive index between alumina and silica is small and there is little reflection, but titanium oxide has a large difference and light due to reflection. Loss is also large. Next, the absorption of the inorganic filler is peculiar to the substance caused by the phenomenon of absorption of light energy due to electronic transition, ion rotation, and elastic resonance vibration in the substance forming the particles. Therefore, it is important to select a substance that does not exhibit this intrinsic absorption in the wavelength range to be used, and the α-alumina single crystal particles of the present invention have absorption in a wide wavelength range of 0.15 μm to 7.5 μm. Absent. Next, as scattering centers inside the inorganic filler, pores in particles, segregation of impurities,
There are scattering due to incompleteness of materials such as different kinds of substances due to precipitation and nonuniformity of composition, and scattering peculiar to substances at discontinuity interfaces of refractive index, that is, grain boundaries based on optical anisotropy of crystal grains.
Since the α-alumina of the present invention is a single crystal produced by the phase transition via the gas phase as described above, it has no pores inside the particles, is highly pure, and has grain boundaries inside. I haven't. Therefore, the inorganic filler of the present invention is a particle having very little internal scattering. As described above, when the α-alumina single crystal particles of the present invention are used, all of reflection, absorption, and scattering are suppressed, and straightness of light at the time of exposure and energy are preserved, so that resolution is not deteriorated and gradation is not deteriorated. Images can be obtained.

Further, the photosensitive member using an inorganic filler in the outermost surface layer often causes mechanical problems due to the shape and particle size distribution of the filler. The α-alumina single crystal particles of the present invention produced by the phase transition via the gas phase have a hexagonal close-packed lattice polyhedron shape close to a sphere, and were conventionally found in a crushed filler having a sharp crushing surface. No black stripe defect image due to damage to the cleaning blade.

Furthermore, since the α-alumina single crystal particles produced by the above-mentioned manufacturing method have a narrow particle size distribution and do not contain a large amount of fine powder, it is preferable to use a filler having a central particle size of 0.1 to 1 μm. Has excellent wear resistance and does not cause uneven wear.

The α-alumina single crystal particles used in the present invention will be described in more detail below.

The α-alumina single crystal particles of the present invention are produced by using transition alumina as a raw material or an alumina raw material which becomes a transition alumina by heat treatment. By transitional alumina is meant all of the alumina having the polymorphic form represented by Al ₂ O ₃ except the α form. Specifically, γ-alumina, δ-alumina, θ-alumina and the like can be exemplified.

The alumina raw material which becomes the transition alumina by heat treatment means a precursor of the transition alumina which gives the desired powdery α-alumina via the transition alumina in the firing step. Specifically, aluminum hydroxide; van sulphate (aluminum sulphate); so-called light vans such as potassium aluminum sulphate and aluminum ammonium sulphate; ammonium aluminum carbonate as well as alumina gels, for example alumina gels produced by the underwater discharge method of aluminum. Etc. can be mentioned.

The method for synthesizing the transition alumina and the alumina raw material which becomes the transition alumina by heat treatment is not particularly limited. For example, aluminum hydroxide is Bayer method, organoaluminum compound (aluminum isopropoxide, etc.)
Can be obtained by the hydrolysis method described above or a method of synthesizing an aluminum compound obtained from an etching waste liquid such as a capacitor as a starting material.

The transition alumina can be obtained by a method of heat-treating aluminum hydroxide, a decomposition method of aluminum sulfate, a light van decomposition method, a vapor phase decomposition method of aluminum chloride, or a decomposition method of ammonium aluminum carbonate.

The above-mentioned transition alumina or an alumina raw material which becomes the transition alumina by heat treatment is hydrogen halide gas in an amount of 1% by volume or more, preferably 5% with respect to the total volume of the atmosphere gas.
Firing is performed in an atmosphere gas of not less than 10% by volume, more preferably not less than 10% by volume. An inert gas such as nitrogen, hydrogen, or argon, and air can be used as a diluent gas for the hydrogen halide gas, which is an atmospheric gas. The pressure of the atmosphere gas containing the hydrogen halide gas is not particularly limited,
It can be arbitrarily selected within a range used industrially. By firing in such an atmosphere gas, the target α-alumina particles can be obtained at a relatively low firing temperature.

Instead of the hydrogen halide gas, a mixed gas of halogen gas and water vapor can be used. In an atmosphere gas in which a halogen gas and water vapor are introduced from a transition alumina or an alumina raw material which becomes a transition alumina by heat treatment, the halogen gas is 1% by volume or more, preferably 5% by volume or more, more preferably 10% with respect to the total volume of the atmosphere gas.
Volume% or more and steam 0.1 volume% or more, preferably 1 volume% or more, more preferably 5 volume% or more are introduced and fired. As the halogen gas and water vapor dilution gas to be introduced, an inert gas such as nitrogen, hydrogen or argon and air can be used. By firing in an atmosphere gas containing a halogen gas and water vapor, the desired α-alumina particles can be obtained at a relatively low firing temperature.

The firing temperature is 600 ° C. or higher, preferably 60.
0 ° C or more and 1400 ° C or less, more preferably 700 ° C or more and 1300 ° C or less, further preferably 800 ° C or more and 120
It is 0 ° C or lower. By controlling the temperature within this temperature range and calcining, it is possible to obtain α-alumina particles having a narrow particle size distribution even immediately after calcining, at a production rate that is industrially advantageous, in which agglomeration of the generated alumina particles does not easily occur.

The appropriate firing time depends on the concentration of the atmospheric gas and the firing temperature and is not necessarily limited, but is preferably 1 minute or longer, more preferably 10 minutes or longer.
It is sufficient to calcine the alumina raw material until the α-alumina particles are crystallized.

In the present invention, any of fluorine, chlorine, bromine and iodine can be used as the halogen, preferably fluorine and chlorine, more preferably chlorine.

The supply source and supply method of the atmospheric gas are not particularly limited. It is sufficient that the above-mentioned atmosphere gas can be introduced into the reaction system in which the raw material such as transition alumina exists. Cylinder gas can usually be used as a supply source, but when an aqueous solution of hydrogen halide, a halogen compound such as ammonium halide, or a halogen-containing polymer compound is used as a raw material such as halogen gas, the vapor pressure thereof Alternatively, it can be used by being decomposed to have the above-mentioned predetermined gas composition. As a gas supply method, either a continuous method or a batch method can be used.

The firing apparatus is not necessarily limited, and a so-called firing furnace can be used. It is desirable that the firing furnace is made of a material that is not corroded by hydrogen halide gas, halogen gas, etc., and further, it is desirable that the firing furnace be provided with a mechanism capable of adjusting the atmosphere. Further, since an acid gas such as hydrogen halide gas or halogen gas is used, it is preferable that the firing furnace be airtight. Industrially, it is preferable to carry out firing in a continuous manner, and for example, a tunnel furnace, a rotary kiln or a pusher furnace can be used.

As the material of the apparatus used in the manufacturing process, it is desirable to use a crucible or boat made of alumina, quartz, acid-resistant brick or graphite, since the reaction proceeds in an acidic atmosphere.

Α-of the present invention having a purity of 99.95% by weight or more
In order to obtain alumina particles, it is desirable to select, as an alumina raw material, an alumina material having an alumina concentration of 99.5% by weight or more and containing as few impurities as possible.

By the above-mentioned production method, α-alumina single crystal particles having no crystal seed in the present invention can be obtained. The α-alumina particles obtained in this way are 0.1 to 1
The particle size can be controlled in μm and the particle size distribution can be narrowed. The α-alumina particles are basically non-aggregating and may or may contain agglomerated particles depending on the raw material or manufacturing conditions, but they can be easily made into single particles by simple pulverization. Is possible.

Next, the electrophotographic photosensitive member used in the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing an electrophotographic photosensitive member of the present invention, in which a photosensitive layer 33 containing a charge generating substance and a binder resin as main components is provided on a conductive support 31. . FIG. 1 shows the case where the outermost surface layer containing the inorganic filler is the entire photosensitive layer.
FIG. 1B shows the case where the outermost surface layer containing the inorganic filler (a) is the surface portion of the photosensitive layer.

In the structure shown in FIG. 2, a charge generating layer 35 containing a charge generating substance as a main component and a charge transporting layer 37 containing a charge transporting substance as a main component are laminated on a conductive support 31. It has a different configuration. FIG. 2 (a) shows the case where the outermost surface layer containing the inorganic filler is the entire charge transport layer, and FIG. 2 (b) shows the case of the surface portion of the charge transport layer.
Is.

In the structure shown in FIG. 3, a photosensitive layer 33 containing a charge generating substance and a binder resin as main components is provided on a conductive support 31, and a protective layer 39 is further provided on the surface of the photosensitive layer. It has a composition. In this case, the outermost surface layer containing the inorganic filler is the protective layer 39.

In the structure shown in FIG. 4, a charge generating layer 35 containing a charge generating substance as a main component and a charge transporting layer 37 containing a charge transporting substance as a main component are laminated on a conductive support 31. And a protective layer 39 on the charge transport layer 37.
Is provided. In this case, the outermost surface layer containing the inorganic filler is the protective layer 39.

FIG. 5 shows a structure in which a charge transport layer 37 containing a charge transport substance as a main component and a charge generating layer 35 containing a charge generating substance as a main component are laminated on a conductive support 31. Further, a protective layer 39 is provided on the charge generation layer 35. In this case, the outermost surface layer containing the inorganic filler is the protective layer 39.

(Regarding Conductive Support) Conductive Support 3
1, those exhibiting conductivity with a volume resistance of 10 ¹⁰ Ω · cm or less, for example, metals such as aluminum, nickel, chromium, nichrome, copper, gold, silver and platinum, metal oxides such as tin oxide and indium oxide , By vapor deposition or sputtering, film-shaped or cylindrical plastic, paper coated, or aluminum, aluminum alloy, nickel, stainless steel, etc. plate and those, after extruded, drawn into a raw tube by a construction method, It is possible to use a tube or the like which has been subjected to surface treatment such as cutting, superfinishing and polishing. Further, the endless nickel belt and the endless stainless belt disclosed in JP-A-52-36016 can also be used as the conductive support 31.

In addition, the conductive support 31 of the present invention may be formed by coating the support with conductive powder dispersed in a suitable binder resin. As the conductive powder, carbon black, acetylene black, aluminum, nickel, iron, nichrome,
Metal powder such as copper, zinc, silver, or conductive tin oxide,
Examples thereof include metal oxide powder such as ITO. Also,
The binder resin used at the same time, polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, poly Vinyl acetate, polyvinylidene chloride, polyarylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinylcarbazole, acrylic resin, silicone resin, epoxy resin, melamine resin , A thermoplastic resin such as a urethane resin, a phenol resin, an alkyd resin, a thermosetting resin, or a photocurable resin. Such a conductive layer can be provided by dispersing these conductive powders and a binder resin in a suitable solvent, for example, tetrahydrofuran, dichloromethane, methyl ethyl ketone, toluene or the like and applying the dispersion.

Further, heat shrinkage of a material such as polyvinyl chloride, polypropylene, polyester, polystyrene, polyvinylidene chloride, polyethylene, chlorinated rubber, or Teflon (registered trademark) containing the above conductive powder on a suitable cylindrical substrate. The one provided with a conductive layer by a tube,
It can be favorably used as the conductive support 31 of the present invention.

(Regarding Photosensitive Layer) The photosensitive layer may have a laminated structure or a single layer structure. In the case of a laminated structure, the photosensitive layer is composed of a charge generating layer containing a charge generating substance and a charge transporting layer containing a charge transporting substance. In the case of a single layer structure,
The photosensitive layer is composed of at least a layer containing a charge generating substance. Each of the photosensitive layer having a laminated structure and the photosensitive layer having a single layer structure will be described below.

(Photosensitive Layer Comprised of Plural Layers) [Charge Generating Layer] The charge generating layer 35 is a layer containing a charge generating substance as a main component, and a binder resin may be used together if necessary. An inorganic material and an organic material can be used as the charge generating substance.

Examples of the inorganic material include crystalline selenium, amorphous selenium, selenium-tellurium, selenium-tellurium-halogen, selenium-arsenic compounds, and amorphous silicon. As amorphous silicon, dangling bonds terminated with hydrogen atoms or halogen atoms, or those doped with boron atoms, phosphorus atoms, etc. are preferably used.

On the other hand, a known material can be used as the organic material. For example, phthalocyanine-based pigments such as metal phthalocyanine and metal-free phthalocyanine, azurenium salt pigment, squaric acid methine pigment, azo pigment having a carbazole skeleton, azo pigment having a triphenylamine skeleton, azo pigment having a diphenylamine skeleton, dibenzothiophene skeleton Having an azo pigment, an azo pigment having a fluorenone skeleton, an azo pigment having an oxadiazol skeleton, an azo pigment having a bisstilbene skeleton, an azo pigment having a distyryl oxadiazol skeleton, and a distyryl carbazole skeleton Azo pigments, perylene pigments, anthraquinone or polycyclic quinone pigments, quinonimine pigments, diphenylmethane and triphenylmethane pigments, benzoquinone and naphthoquinone pigments, cyanine and azomethine dyes, Goido pigments, bisbenzimidazo - such as Le based pigments. These charge generating substances can be used alone or as a mixture of two or more kinds.

As the binder resin used as necessary in the charge generation layer 35, polyamide, polyurethane,
Epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene,
Examples thereof include poly-N-vinylcarbazole and polyacrylamide. These binder resins can be used alone or as a mixture of two or more kinds. Also,
As a binder resin for the charge generation layer, in addition to the above-mentioned binder resin, a polymer charge transport material (for example, JP-A-64-172).
No. 8, JP-A-64-13061, JP-A-64
-19049, JP-A-4-11627, JP-A-4-225014, and JP-A-4-230767.
Japanese Patent Application Laid-Open No. 4-320420, Japanese Patent Application Laid-Open No. 5-2
No. 32727, No. 6-234838, No. 6-234839, No. 6-295077.
JP-A-7-56374, JP-A-7-32
5409, JP-A-9-80772, JP-A-9-80783, and JP-A-9-80784,
JP-A-9-127713, JP-A-9-21187
No. 7, JP-A-9-222740, JP-A 9-
No. 265197, JP-A No. 9-265201,
JP-A-9-297419 and JP-A-9-30495.
No. 6 gazette) can be used. Among these polymer charge transport materials, polycarbonate having a triarylamine structure in its main chain and / or side chain is effective.

The amount of the binder resin used in the charge generation layer 35 is 0 to 500 with respect to 100 parts by weight of the charge generation material.
Suitable is parts by weight, preferably 0 to 200 parts by weight.

Further, a low molecular weight charge transport material may be added to the charge generation layer 35, if necessary. The low molecular weight charge transport materials that can be used in combination with the charge generation layer 35 include hole transport materials and electron transport materials.

Examples of the electron transport material include chloranil, bromanil, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone, 2,4,5,7-tetranitroxanthone,
2,4,8-trinitrothioxanthone, 2,6,8-
Examples thereof include electron-accepting substances such as trinitro-4H-indeno [1,2-b] thiophen-4-one, 1,3,7-trinitrodibenzothiophene-5,5-dioxide, and diphenoquinone derivatives. These electron transport materials can be used alone or as a mixture of two or more kinds.

Examples of the hole-transporting substance include the electron-donating substances shown below, which are preferably used. Examples of the hole transport material include oxazole derivatives, oxadiazole derivatives, imidazole derivatives, monoarylamine derivatives, diarylamine derivatives, triarylamine derivatives, stilbene derivatives, α-phenylstilbene derivatives, benzidine derivatives, diarylmethane derivatives, triaryls. Other known materials such as a methane derivative, a 9-styrylanthracene derivative, a pyrazoline derivative, a divinylbenzene derivative, a hydrazone derivative, an indene derivative, a butadiene derivative, a pyrene derivative, a bisstilbene derivative, an enamine derivative, and the like can be given. These hole transport materials can be used alone or as a mixture of two or more kinds.

The amount of the low molecular weight charge transport material used in the charge generation layer 35 is 0 to 5 with respect to 100 parts by weight of the charge generation material.
00 parts by weight, preferably 0 to 300 parts by weight are suitable.

As a method for forming the charge generation layer 35, a vacuum thin film forming method and a casting method from a solution dispersion system can be largely cited. For the former vacuum thin film forming method, a vacuum deposition method, a glow discharge decomposition method, an ion plating method, a sputtering method, a reactive sputtering method, a CVD method, etc. are used, and the above-mentioned inorganic materials and organic materials are favorably used. Can be formed. Further, in order to provide a charge generation layer by a casting method described later, tetrahydrofuran, dioxane, dioxolane, toluene, dichloromethane, monochlorobenzene, dichloroethane, together with the above-mentioned inorganic or organic charge generation material if necessary a binder resin,
Cyclohexanone, cyclopentanone, anisole, xylene, methyl ethyl ketone, acetone, ethyl acetate,
It can be formed by dispersing with a ball mill, an attritor, a sand mill, a bead mill or the like using a solvent such as butyl acetate, and appropriately diluting the dispersion liquid and applying it. Further, if necessary, a leveling agent such as dimethyl silicone oil or methylphenyl silicone oil can be added. Application is dip coating method, spray coating,
It can be performed using a bead coat method, a ring coat method, or the like.

The film thickness of the charge generation layer provided as described above is suitably about 0.01 to 5 μm, preferably 0.05 to 2 μm.

[Charge Transport Layer] The charge transport layer 37 can be formed by dissolving or dispersing a charge transport substance and a binder resin in an appropriate solvent, applying the solution on the charge generating layer 35, and drying.

As the charge transport material, the charge generation layer 3 is used.
The electron transporting material, hole transporting material, and polymer charge transporting material described in 5 can be used.

As the binder resin, polystyrene,
Styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer,
Polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyvinylidene chloride, polyarylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly- Thermoplastic or thermosetting resins such as N-vinylcarbazole, acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, phenol resin, alkyd resin and the like can be mentioned.

The amount of the charge transport material is 100% of the binder resin.
20 to 300 parts by weight, preferably 40 to 300 parts by weight
150 parts by weight is suitable. However, when the polymer charge transport material is used, it can be used alone or in combination with a binder resin.

As the solvent used for coating the charge transport layer 37, the same solvents as those for the charge generating layer can be used, but those capable of dissolving the charge transport substance and the binder resin well are suitable. These solvents may be used alone or in combination of two or more. In addition, the same coating method as that for the charge generation layer 35 can be used to form the charge transport layer 37.

If necessary, a plasticizer and a leveling agent may be added. As the plasticizer that can be used in combination with the charge transport layer 37, those used as plasticizers for general resins such as dibutyl phthalate and dioctyl phthalate can be used as they are.
About 0 to 30 parts by weight is suitable for 100 parts by weight.

As a leveling agent that can be used in combination with the charge transport layer 37, silicone oils such as dimethyl silicone oil and methylphenyl silicone oil, and polymers or oligomers having a perfluoroalkyl group in the side chain are used. , Binder resin 100
About 0 to 1 part by weight is suitable with respect to parts by weight.

The thickness of the charge transport layer 37 is preferably about 5 to 50 μm, and is preferably 10 to 40 μ in view of image characteristics such as resolution and background stain and electric characteristics such as charging potential and sensitivity.
m is suitable.

The photoconductor shown in FIG. 5 is different from the photoconductor shown in FIG. 4 in the positions of the charge generation layer 35 and the charge transport layer 37.

(Regarding Inorganic Filler) Further, when the charge transport layer 37 is the outermost surface layer of the photoreceptor, the charge transport layer 37
An inorganic filler is contained in the entire layer or surface portion of the above for the purpose of improving wear resistance. By using single crystal particles of α-alumina that are homogeneous and do not have crystal seeds inside as this inorganic filler, it has high durability and does not generate image deletion even after repeated use, and further has high resolution and gradation. Is highly
It is possible to continuously obtain a good image without background stains and reduction in image density. The method for producing single crystal particles of α-alumina which is homogeneous and does not have a crystal seed in the present invention is as described above,
JP-A-6-191833, JP-A-6-19183
No. 6 and Japanese Patent Laid-Open No. 7-206430.

The α-alumina particles of the present invention have a high pressure TE.
It was revealed by M (Hitachi: 1200 kVA) that the particles were homogeneous without crystal seeds, and by imaging plate method X-ray analysis (R-AIXIIC, manufactured by Rigaku Denki) that they were single crystal particles. There is. Further, the α-alumina particles of the present invention are used in the field emission scanning line electron microscope F.
From the observation by E-SEM (S-4200, manufactured by Hitachi, Ltd.), it is known that the particle size distribution is very narrow in a hexagonal close-packed lattice polyhedron shape close to a sphere having no crushing surface.
Further, the α-alumina particles of the present invention have a sodium content of Na ₂ by quantification of impurity ions by optical emission analysis.
It is as low as 10 ppm or less when converted to O, and has a high purity of 99.99 or more when calculated by subtracting the amount of impurities from the whole.

The α-alumina single crystal particles preferably used in the present invention have a median particle diameter of 0.1 to 1.0 μm,
If it is smaller than 0.1 μm, aggregation of the inorganic filler easily occurs in the coating liquid, which makes uniform coating difficult. As a result,
Wear unevenness occurs during repeated use. Also, 1.0
If it is larger than μm, the surface becomes more uneven as a result of repeated use, which induces toner filming and damage to the cleaning blade, resulting in abnormal images such as black streaks and streaky white spots. In addition, productivity adverse effects such as acceleration of the sedimentation of the inorganic filler in the coating liquid also appear. The central particle diameter used here is a number average value by SEM image, a volume average particle diameter by a laser explanation method, a weight average particle diameter and the like.

As the inorganic filler of the present invention, in addition to the α-alumina single crystal particles, if necessary, metal powder of copper, tin, aluminum, indium, etc., silica, tin oxide, zinc oxide, titanium oxide, and poly-alloys. Crystalline alumina, zirconium oxide, indium oxide, antimony oxide, bismuth oxide, calcium oxide, metal oxide such as tin oxide doped with antimony, indium oxide doped with tin, tin fluoride, calcium fluoride, aluminum fluoride, etc. Particles such as metal fluoride, potassium titanate, and boron nitride may be used together. Further, it is possible to perform a surface treatment for the purpose of improving the dispersibility of these inorganic fillers, and as the surface treatment agent used at this time, a titanate coupling agent, an aluminum coupling agent, a zircoaluminate cup is used. Examples thereof include ring agents, higher fatty acids, silane coupling agents, Al ₂ O ₃ , TiO ₂ , ZrO ₂ , silicone, aluminum stearate, and a mixture treatment thereof.

The proportion of the inorganic filler contained in the outermost surface layer depends on the desired wear resistance, the particle size of the inorganic filler, the material,
Although it depends on various factors such as the image forming process used, it is 0.5 to 50% by weight, preferably 2 to 40% by weight, based on the total amount of the surface portion in which the inorganic filler is dispersed.

For the surface portion containing the inorganic filler, for example, the inorganic filler is combined with an organic solvent and dispersed by a conventional method such as a ball mill, an attritor, a sand mill, a bead mill, or ultrasonic waves, and then a binder resin is added for coating. Provided by. When the outermost surface layer containing the inorganic filler is all the layers of the charge transport layer 37 as shown in FIG. 2A, the charge generation layer 35 is coated with a coating liquid containing the inorganic filler, the charge transport material and the binder resin. If the inorganic filler is present only on the surface portion of the charge transport layer 37 as shown in FIG. 2B, the coating liquid containing the charge transport substance and the binder resin is used to charge the coating liquid. The coating is applied on the generation layer 35, and a coating liquid containing a charge transport substance, a binder resin and an inorganic filler is applied thereon.

As the coating method used at this time, the coating method described for the charge generation layer 35 can be used. This coating solution may contain a dispersant such as a polycarboxylic acid compound, if necessary.
Additives such as a charge transport material, a leveling agent, and a plasticizer are used. These binder resins and additives may be added before, during or after the inorganic filler dispersion treatment. The organic solvent used in this coating liquid depends on the dispersibility of the inorganic filler, the coating method, etc., but generally, those described for the charge generation layer 35 can be used, and two or more kinds of solvents can be used. It may be mixed.

As the materials such as the binder resin and the charge transport material used for the outermost surface portion in which the inorganic filler is dispersed, those mentioned in the charge transport layer 37 can be used, but the inorganic filler is used only for the surface portion of the charge transport layer. In the case of containing, the type and composition of the material used for the charge transporting portion of the lower layer containing no inorganic filler can be changed as necessary. The binder resin used here is contained for the purpose of fixing the inorganic filler and maintaining the strength of the outermost surface layer. The minimum amount of the binder resin is 25 parts by weight or more, preferably 50 parts by weight or more with respect to 100 parts by weight of the inorganic filler. Is. In addition, the charge transport material and other additives can be used in the same addition ratio as in the charge transport layer 37.

The thickness of the surface portion containing the inorganic filler may be all layers of the charge transport layer 37, but is preferably 20 μm or less in terms of image characteristics and electrical characteristics, and more preferably in the range of 1 to 10 μm. Is.

(Regarding Polycarboxylic Acid Compound) The dispersant used in the coating liquid for the inorganic filler dispersion layer is necessary for the purpose of improving the dispersibility of the inorganic filler during preparation of the coating liquid and enhancing the stability of the coating liquid. Added accordingly. As this dispersant, an inorganic filler is dispersed to a value close to the primary particle size,
The use of a polycarboxylic acid compound is particularly effective in that it does not adversely affect the electrical characteristics and image characteristics.

As the polycarboxylic acid compound, a low molecular weight compound having a plurality of carboxylic acid residues, an oligomer,
It refers to a polymer compound, and examples thereof include organic fatty acids and highly oxidized resins. The polycarboxylic acid compound is an oligomer, and the polymer compound is a polyester resin, an acrylic resin, a copolymer using acrylic acid or methacrylic acid,
Examples thereof include styrene-acrylic copolymer. The acid value of the polycarboxylic acid compound used here is 10 to 4
Those of 00 (mgKOH / g) can be effectively used.
(The acid value is defined as the number of milligrams of potassium hydroxide required to neutralize the free fatty acid contained in 1 g.) The addition amount of this polycarboxylic acid compound is 100 parts by weight of the inorganic filler contained. To 0.01 to 50 parts by weight, preferably 0.1 to 20 parts by weight.

(Photosensitive layer is a single layer) As shown in FIG. 1, the single-layer structure is such that a photosensitive layer 33 in which at least a charge generating substance is dispersed in a binder resin is provided on a conductive support. . The photosensitive layer 33 can be formed by dissolving or dispersing, in addition to the charge generating substance and the binder resin, a charge transporting substance in a suitable solvent, and applying and drying the solution. If necessary, a plasticizer, a leveling agent, etc. may be added. As the charge generating substance, the charge transporting substance, the plasticizer and the leveling agent, the same ones as described above for the charge generating layer 35 and the charge transporting layer 37 can be used.

As the binder resin, in addition to the binder resins already mentioned in the charge transport layer 37, the charge generation layer 35 can be used.
You may mix and use the binder resin mentioned in above. Further, the above-mentioned polymer charge transport materials can also be used favorably. The amount of the charge generating substance is preferably 1 to 40 parts by weight, and the amount of the charge transporting substance is preferably 0 to 190 parts by weight, and more preferably 50 to 100 parts by weight with respect to 100 parts by weight of the binder resin.
It is 150 parts by weight. The photosensitive layer 33 is formed by dipping or spraying a coating liquid in which a charge-generating substance and a binder resin are dispersed together with a charge-transporting substance, if necessary, using a solvent such as tetrahydrofuran, dioxane, dichloroethane, cyclohexane by a disperser. , Bead coat, ring coat or the like. The thickness of the photosensitive layer is
About 5 to 25 μm is suitable.

When the single-layered photosensitive layer 33 is the outermost surface layer of the photosensitive member, the entire surface of the photosensitive layer 33 (FIG. 1A) or its surface portion (FIG. 1B) has abrasion resistance. An inorganic filler is contained for the purpose of improving By using single crystal particles of α-alumina that are homogeneous and do not have crystal seeds inside as this inorganic filler, it has high durability and does not generate image deletion even after repeated use, and further has high resolution and gradation. The excellent image is continuously obtained without any background stain or image density reduction. Here, the photoreceptor shown in FIG.
It can be obtained by applying a photosensitive layer coating liquid containing an inorganic filler onto a conductive support. In the photoreceptor shown in FIG. 1 (b), a photosensitive layer coating liquid containing no inorganic filler is coated on a conductive support, and then a photosensitive layer coating liquid containing an inorganic filler is coated thereon. It can be obtained by working.

The above-mentioned inorganic fillers can be used as the inorganic filler dispersed in the surface portion of this single-layer structure, and the binder resin and other constituent materials are basically used for the photosensitive layer 33 of the single-layer structure. The polycarboxylic acid compound described in the charge transport layer 37, a plasticizer, a leveling agent, and the like can be added. The charge transport layer 3 may be the addition amount of these contained materials, the method for producing the inorganic filler dispersion layer, and the film thickness.
7. The same matters as described for the single-layered photosensitive layer 33 can be applied.

(Undercoat Layer) In the photoreceptor of the present invention, an undercoat layer can be provided between the conductive support 31 and the photosensitive layer. The subbing layer generally contains a resin as a main component, but considering that the photosensitive layer is coated on the resin with a solvent, the resin may be a resin having high solvent resistance to a general organic solvent. desirable. Examples of such resins include polyvinyl alcohol, casein, water-soluble resins such as sodium polyacrylate, copolymer nylon, alcohol-soluble resins such as methoxymethylated nylon, polyurethane, melamine resin, phenol resin, alkyd-
Examples thereof include melamine resins, epoxy resins, and other curable resins that form a three-dimensional network structure. Further, in order to prevent moire and reduce the residual potential, a fine powder pigment of a metal oxide such as titanium oxide, silica, alumina, zirconium oxide, tin oxide or indium oxide may be added to the undercoat layer.

These undercoat layers can be formed by using an appropriate solvent and coating method as in the above-mentioned photosensitive layer.
Further, as the undercoat layer of the present invention, a silane coupling agent,
A titanium coupling agent, a chromium coupling agent, etc. can also be used. In addition to the above, the undercoat layer of the present invention includes A
The l ₂ O ₃ and those provided by anodic oxidation, organic materials and SiO ₂ such as polyparaxylylene (parylene), SnO _2, TiO
An inorganic substance such as ₂ , ITO or CeO ₂ provided by a vacuum thin film forming method can also be used favorably. Besides these, known ones can be used. The thickness of the undercoat layer is suitably 0 to 5 μm.

(About protective layer) In the photoreceptor of the present invention,
For the purpose of protecting the photosensitive layer, as shown in FIG.
A protective layer 39 may be provided on the surface side of No. 3 or on the charge transport layer 37 or the charge generation layer 35 of the laminated type photoreceptor as shown in FIGS. When the protective layer 39 is provided, the photosensitive layer 33, the charge transport layer 37 on the surface side forming the photosensitive layer 33, and the charge generation layer 35 do not need to contain an inorganic filler. Since the protective layer 39 is a layer on the outermost surface side of the photoconductor and is required to have high abrasion resistance, it is effective to contain an inorganic filler. However, as this inorganic filler, it is homogeneous and does not have crystal seeds inside. -By using single crystal particles of alumina, it has high durability, does not generate image deletion even after repeated use, has high resolution and gradation, and is a good image without background stains and image density reduction. Is continuously obtained.

As the binder resin used in this protective layer, ABS resin, ACS resin, olefin-vinyl monomer copolymer, chlorinated polyether, aryl resin, phenol resin, polyacetal, polyamide, polyamideimide, polyacrylate, poly Allyl sulfone, polybutylene, polybutylene terephthalate, polycarbonate, polyether sulfone, polyethylene,
Resins such as polyethylene terephthalate, polyimide, acrylic resin, polymethylpentene, polypropylene, polyphenylene oxide, polysulfone, polystyrene, polyarylate, AS resin, butadiene-styrene copolymer, polyurethane, polyvinyl chloride, polyvinylidene chloride, epoxy resin, etc. Can be used together.

As the inorganic filler dispersed in the protective layer 39, the above-mentioned ones can be used in combination in addition to α-alumina. If necessary, the polycarboxylic acid compound, the plasticizer and the leveling agent can be used in the same manner as described for the charge transport layer 37. Agents and the like are added. Further, as the addition amount of these materials, the dispersion method of the inorganic filler, and the manufacturing method of the protective layer 39, the same matters as those described for the charge transport layer 37 can be applied. The protective layer 3
A suitable thickness of 9 is about 0.5 to 5 μm.

(Regarding Intermediate Layer) In the photoreceptor of the present invention, an intermediate layer can be provided between the photosensitive layer 33 or the charge transport layer 37 and the protective layer 39. A binder resin is generally used as a main component in the intermediate layer. Examples of these resins include polyamide, alcohol-soluble nylon, water-soluble polyvinyl butyral, polyvinyl butyral, and polyvinyl alcohol. As a method of forming the intermediate layer, a general coating method can be adopted as described above.
The thickness of the intermediate layer is preferably about 0.05 to 2 μm.

(Regarding Addition of Antioxidant) Further, in the present invention, for the purpose of improving the environment resistance, in particular, for the purpose of preventing a decrease in sensitivity and an increase in residual potential, a charge generation layer,
An antioxidant can be added to each layer such as the charge transport layer, the undercoat layer, the protective layer and the intermediate layer. The following may be mentioned as antioxidants that can be used in the present invention.

(A) Phenolic compound: 2,6-di-
t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, stearyl-β- (3,5-di-t-butyl-4-
Hydroxyphenyl) propionate, 2,2'-methylene-bis- (4-methyl-6-t-butylphenol), 2,2'-methylene-bis- (4-ethyl-6-
t-butylphenol), 4,4'-thiobis- (3-
Methyl-6-t-butylphenol), 4,4'-butylidenebis- (3-methyl-6-t-butylphenol), 1,1,3-tris- (2-methyl-4-hydroxy-5-t-butyl) Phenyl) butane, 1,3,5-
Trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, tetrakis- [methylene-3- (3 ', 5'-di-t-butyl-
4′-hydroxyphenyl) propionate] methane,
Bis [3,3'-bis (4'-hydroxy-3'-t-
(Butylphenyl) butyric assid] crycol ester, tocopherols, etc.

(B) Para-phenylenediamines: N-phenyl-N'-isopropyl-p-phenylenediamine, N, N'-di-sec-butyl-p-phenylenediamine, N-phenyl-N-sec-butyl. -P-phenylenediamine, N, N'-di-isopropyl-p-phenylenediamine, N, N'-dimethyl-N, N'-di-t-butyl-p-phenylenediamine and the like.

(C) Hydroquinones: 2,5-di-t
-Octyl hydroquinone, 2,6-didodecyl hydroquinone, 2-dodecyl hydroquinone, 2-dodecyl-5-chlorohydroquinone, 2-t-octyl-5-
Methyl hydroquinone, 2- (2-octadecenyl)-
5-methylhydroquinone and the like.

(D) Organic sulfur compounds: dilauryl-
3,3'-thiodipropionate, distearyl-3,
3'-thiodipropionate, ditetradecyl-3,
3'-thiodipropionate and the like.

(E) Organophosphorus compounds: triphenylphosphine, tri (nonylphenyl) phosphine, tri (dinonylphenyl) phosphine, tricresylphosphine, tri (2,4-dibutylphenoxy) phosphine and the like.

These compounds are known as antioxidants for rubbers, plastics, fats and oils, and commercially available products are easily available. The addition amount of the antioxidant in the present invention is 0.01 to 10% by weight based on the total weight of the layer to be added.
Is.

Next, the image forming method and the image forming apparatus of the present invention will be described with reference to the drawings. The image forming method and the image forming apparatus of the present invention use a photoreceptor containing single crystal particles of α-alumina, in which the outermost surface layer of the present invention is at least homogeneous as an inorganic filler and has no crystal seed inside, for example, Transfer the toner image to the image carrier (transfer paper) after at least the steps of charging the photoreceptor, exposing the image, and developing.
An image forming method and an image forming apparatus are formed by a process of fixing and cleaning the surface of a photoconductor. In some cases, an image forming method or the like in which an electrostatic latent image is directly transferred to a transfer body and developed, does not necessarily have the above-described process of disposing on a photoreceptor.

FIG. 6 is a schematic view showing an example of the image forming apparatus. The charging charger 3 is used as a means for uniformly charging the photoconductor. As the charging means, a corotron device, a scorotron device, a solid-state discharge element, a needle electrode device, a roller charging device, a conductive brush device, etc. are used, and all known methods can be used.

Next, the image exposure section 5 is used to form an electrostatic latent image on the uniformly charged photoreceptor. This light source includes a fluorescent lamp, a tungsten lamp, a halogen lamp, a mercury lamp, a sodium lamp, and a light emitting diode (LE
D), semiconductor lasers (LD), electroluminescence (EL) and the like can be used in general.
Further, various filters such as a sharp cut filter, a bandpass filter, a near infrared cut filter, a dichroic filter, an interference filter, and a color temperature conversion filter can be used to irradiate only light in a desired wavelength range.

Next, the developing unit 6 is used to visualize the electrostatic latent image formed on the photosensitive member. As a developing method, there are a one-component developing method using a dry toner, a two-component developing method, and a wet developing method using a wet toner. When the photoreceptor is positively (negatively) charged and imagewise exposed, a positive (negative) electrostatic latent image is formed on the surface of the photoreceptor. A positive image can be obtained by developing the toner with negative (positive) polarity toner (electrodetection fine particles), and a negative image can be obtained by developing the toner with positive (negative) polarity toner.

Next, the transfer charger 10 is used to transfer the toner image visualized on the photoconductor onto the transfer body. Further, the pre-transfer charger 7 may be used in order to perform the transfer better. As these transfer means, an electrostatic transfer method using a transfer charger, a bias roller, a mechanical transfer method such as an adhesive transfer method, a pressure transfer method, or a magnetic transfer method can be used. As the electrostatic transfer method, the charging means can be used.

Next, the separation charger 11 and the separation claw 12 are used as means for separating the transfer member from the photosensitive member. As other separating means, electrostatic attraction induction separation, side end belt separation, tip grip conveyance, curvature separation, etc. are used.
The charging means can be used as the separation charger.

Next, the fur brush 14 and the cleaning blade 15 are used to clean the toner remaining on the photosensitive member after the transfer. Further, the pre-cleaning charger 13 may be used to perform the cleaning more efficiently. As other cleaning means, there are a web method, a magnet brush method and the like, but each may be used alone or in combination with a plurality of methods.

Next, a neutralizing means is used for the purpose of removing the latent image on the photosensitive member, if necessary. As the static elimination means, the static elimination lamp 2 and the static elimination charger are used, and the exposure light source and the charging means can be used respectively.

Other known processes such as document reading, paper feeding, fixing, and paper discharging that are not close to the photoconductor can be used.

The present invention is an image forming method and an image forming apparatus using the electrophotographic photosensitive member according to the present invention for such image forming means.

The image forming means may be fixedly incorporated in a copying machine, a facsimile machine or a printer, or may be detachably incorporated in these machines in the form of a process unit. . FIG. 7 is a schematic view showing an example of a process unit for an image forming apparatus. The process unit for an image forming apparatus is a device (component) which has a built-in photoconductor and at least one of a charging unit, a developing unit, a transfer unit, a cleaning unit, and a charge eliminating unit, which are detachable. The present invention provides at least one of a photoreceptor containing a single crystal particle of α-alumina whose outermost surface layer is homogeneous as an inorganic filler and does not have crystal seeds therein, and charging, developing, transferring, cleaning and neutralizing means. An integrated process unit for an image forming apparatus is provided.

[0115]

EXAMPLES Next, the present invention will be described in more detail by way of examples, but the present invention is not limited to the following examples. All parts used in the examples are parts by weight.

Example 1 An undercoat layer coating liquid, a charge generating layer coating liquid, and a charge transport layer coating liquid having the following compositions were sequentially coated and dried on an φ30 mm aluminum drum. An undercoat layer of 3.5 μm, a charge generation layer of 0.2 μm, and a charge transport layer of 22 μm were formed. The coating liquid for the outermost surface layer containing inorganic filler is prepared by dispersing the following inorganic filler and solvent in a ball mill for 24 hours using alumina balls, and adding a binder resin, an aliphatic polyester, a charge-transporting substance and a solvent to the dispersion liquid. did. This coating solution was spray coated on the charge transport layer and dried to provide an outermost surface layer containing an inorganic filler of 3 μm to obtain an electrophotographic photoreceptor of the present invention.

[0117] [Coating liquid for undercoat layer]     Alkyd resin (Beckosol 1307-60-EL, (Manufactured by Dainippon Ink and Chemicals) 6 parts     Melamine resin (Super Beckamine G-821-60,       (Manufactured by Dainippon Ink and Chemicals) 4 parts     Titanium oxide 40 parts     Methyl ethyl ketone 50 parts

[0118] [Coating liquid for charge generation layer]   2.5 parts of bisazo pigment with the following structure

[Chemical 1] Polyvinyl butyral (XYHL, manufactured by UCC) 0.5 part Cyclohexanone 200 parts Methyl ethyl ketone 80 parts

[0119] [Coating liquid for charge transport layer]     Bisphenol Z polycarbonate       (Panlite TS-2050 Teijin Kasei) 10 parts     7 parts of a low molecular weight charge transport material (D-1) having the following structure

[Chemical 2] Tetrahydrofuran 100 parts 1% Silicone oil (KF50-100CS, Shin-Etsu Chemical Co., Ltd.) tetrahydrofuran solution 1 part

[0120] [Coating liquid for inorganic filler-containing layer]     Α-alumina single crystal particles that are homogeneous and have no internal crystal seeds       (Sumicorundum AA-03: Sumitomo Chemical Co., Ltd.) 2 parts Binder resin     Bisphenol Z polycarbonate       (Panlite TS-2050, manufactured by Teijin Kasei) 4 parts     Small molecule charge transport material       (Low-Molecular Charge Transport Material D-1 Described in Charge Transport Layer) 3 parts     Cyclohexanone 60 parts     Tetrahydrofuran 200 parts

Example 2 Except that the inorganic filler of the coating liquid for an inorganic filler-containing layer of Example 1 was changed to 2 parts of single crystal particles of α-alumina (Sumicorundum AA-05: manufactured by Sumitomo Chemical Co., Ltd.). An electrophotographic photosensitive member was produced in the same manner as in Example 1.

Example 3 Except that the inorganic filler of the coating liquid for an inorganic filler-containing layer of Example 1 was changed to 2 parts of single crystal particles of α-alumina (Sumicorundum AA-07: Sumitomo Chemical Co., Ltd.). An electrophotographic photosensitive member was produced in the same manner as in Example 1.

[Example 4] The inorganic filler in the coating liquid for an inorganic filler-containing layer of Example 1 was changed to 2 parts by weight of α-alumina single crystal particles (Sumicorundum AA-03: manufactured by Sumitomo Chemical Co., Ltd.), and coated. A polycarboxylic acid compound (BYK-P10) is used as a dispersant when the inorganic filler is dispersed in the process fluid preparation process.
4, manufactured by Big Chemie) was added, the coating liquid was added in an amount of 0.02 part, and the film thickness of the outermost surface layer was set to 5 μm to prepare an electrophotographic photosensitive member in the same manner as in Example 1.

[Example 5] The inorganic filler in the coating liquid for the inorganic filler-containing layer of Example 1 was changed to 2 parts by weight of α-alumina single crystal particles (Sumicorundum AA-05: manufactured by Sumitomo Chemical Co., Ltd.), and coated. A polycarboxylic acid compound (BYK-P10) is used as a dispersant when the inorganic filler is dispersed in the process fluid preparation process.
4, manufactured by Big Chemie) was added, the coating liquid was added in an amount of 0.02 part, and the film thickness of the outermost surface layer was set to 5 μm to prepare an electrophotographic photosensitive member in the same manner as in Example 1.

[Example 6] The inorganic filler in the coating liquid for an inorganic filler-containing layer of Example 1 was changed to 2 parts by weight of α-alumina single crystal particles (Sumicorundum AA-07: manufactured by Sumitomo Chemical Co., Ltd.) and coated. A polycarboxylic acid compound (BYK-P10) is used as a dispersant when the inorganic filler is dispersed in the process of preparing a working solution.
4, manufactured by Big Chemie) was added, the coating liquid was added in an amount of 0.02 part, and the film thickness of the outermost surface layer was set to 5 μm to prepare an electrophotographic photosensitive member in the same manner as in Example 1.

Example 7 An electrophotographic photosensitive member was produced in the same manner as in Example 4 except that 4 parts of polycarbonate (Panlite C-1400, manufactured by Teijin Kasei) was used as the binder resin in Example 4.

[Example 8] The same as Example 4 except that the binder resin of Example 4 was changed to 7 parts of the polymeric charge transport material (PD-1) having the following structure, and the low molecular charge transport material was not added. An electrophotographic photoreceptor was produced.

[Chemical 3] k = 0.42, j = 0.58 Mw = 16000 (polystyrene conversion) (PD-1)

[Comparative Example 1] The inorganic filler in the coating liquid for an inorganic filler-containing layer of Example 1 was changed to 2 parts of rutile-titanium oxide powder (CR-EL: manufactured by Ishihara Sangyo), and the coating liquid preparation process was performed. Example except that a polycarboxylic acid compound (BYK-P104, manufactured by BYK-Chemie) was added as a dispersant at the time of dispersing the inorganic filler, the addition amount of the coating liquid was 0.02 part, and the film thickness of the outermost surface layer was 3 μm. An electrophotographic photosensitive member was produced in the same manner as in 1.

[Comparative Example 2] Spherical silica particles (KE-P) were used as the inorganic filler of the inorganic filler-containing layer coating liquid of Example 1.
(30: manufactured by Nippon Shokubai Co., Ltd.) An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the amount was changed to 1.5 parts.

[Comparative Example 3] Example 3 except that the inorganic filler in the coating liquid for an inorganic filler-containing layer of Example 1 was changed to 2 parts of α-alumina single crystal particles (AA-2: manufactured by Sumitomo Chemical Co., Ltd.). An electrophotographic photosensitive member was produced in the same manner as in 1.

[Comparative Example 4] Alumina ultrafine particles (Alu) were used as the inorganic filler of the inorganic filler-containing layer coating liquid of Example 1.
minimum Oxide C: made by Nippon Aerosil) 2
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the parts were changed.

[Comparative Example 5] The inorganic filler of the coating liquid for the inorganic filler-containing layer of Example 1 was replaced with α-alumina powder (AKP).
-30: Sumitomo Chemical Co., Ltd.) 2 parts, and polycarboxylic acid compound (BYK-P104, manufactured by BYK-Chemie) as a dispersant at the time of dispersing the inorganic filler in the coating liquid preparation process.
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the coating liquid was added in an amount of 0.02 part and the film thickness of the outermost surface layer was 5 μm.

[Comparative Example 6] The inorganic filler of the coating liquid for the inorganic filler-containing layer of Example 1 was replaced with α-alumina powder (AL-
(M41: Sumitomo Chemical Co., Ltd.) Example 1 except that 2 parts were used
An electrophotographic photoreceptor was prepared in the same manner as in.

[Comparative Example 7] The inorganic filler of the coating liquid for the inorganic filler-containing layer of Example 1 was replaced with α-alumina powder (AMS).
-12: Sumitomo Chemical Co., Ltd.) Example 1 except that 2 parts were used.
An electrophotographic photoreceptor was prepared in the same manner as in.

[Comparative Example 8] An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the inorganic filler-containing outermost layer of Example 1 was not provided.

[0136]

[Table 1] The α-alumina particles of the examples are homogeneous particles having no crystal seed inside by an ultra-high pressure scanning electron microscope (Hitachi: 1200 kVA), and an imaging plate method X-ray analysis (Rigaku Denki: R- It has been clarified by AIXSI C) that it is a single crystal particle. Also, this α
-Alumina particles are a field emission scanning electron microscope FE-
From observation with SEM (Hitachi: S-4200), it has been confirmed that the particle size distribution is very narrow in a hexagonal close-packed lattice polyhedron shape that is close to a sphere without a fracture surface.
Further, the α-alumina particles have a low sodium content of 10 ppm or less in terms of Na ₂ O determined by quantification of impurity ions by optical emission analysis, and have a high content of 99.99% by weight or more calculated by subtracting the amount of impurities from the whole. It is pure.

Ricoh manufactured by mounting the electrophotographic photoconductors of Examples 1 to 8 and Comparative Examples 1 to 7 manufactured as described above in a process unit for an electrophotographic apparatus and converting an image exposure light source into a 655 nm semiconductor laser. imagioMF2200
Image evaluation was performed by using. First, an initial image was taken in an environment of a temperature of 25 ° C. and a humidity of 55%, and then, as an acceleration test of a charging load, it was left in an ozone gas atmosphere of 5 ppm for 10 hours, and then an image change was confirmed in the same environment as the initial. After that, copying was further performed on 30,000 sheets, and the abrasion amount of the photoconductor and the image change after the copying were examined. The results are shown in Tables 2 and 3.

[0138]

[Table 2]

[Table 3] From the evaluation results of Table 2 and Table 3, in the photoreceptor in which the inorganic filler is dispersed in the outermost surface layer for the purpose of improving the wear resistance,
As shown in Examples 1 to 8, the use of another filler of Comparative Examples 1 to 7 by using single crystal particles of α-alumina that are homogeneous and do not have crystal seeds therein as the inorganic filler, and Compared with the case where the surface layer containing the inorganic filler of Comparative Example 8 was not used, image deletion and background stain did not occur, both gradation and resolution were high, and a good image with no decrease in image density was maintained. You can see that you can get it.

Therefore, by using α-alumina single crystal particles that are homogeneous and have no crystal seed inside as the inorganic filler in the outermost surface layer of the present invention, it has high durability and can be used repeatedly. It has been found that it is possible to provide a high-performance and highly reliable electrophotographic photosensitive member that can continuously obtain a good image. In addition, it was also found that the image forming apparatus and the process unit for the image forming apparatus using the electrophotographic photosensitive member of the present invention have high performance and high reliability.

[0140]

According to the present invention, in an electrophotographic photosensitive member containing at least an inorganic filler and a binder resin in the outermost surface layer, a single α-alumina which is homogeneous as the inorganic filler and has no internal crystal seeds is used. By using the crystal particles, it is possible to provide a highly durable, high-performance and highly reliable electrophotographic photoreceptor having high abrasion resistance and capable of maintaining high image quality. Further, by using the electrophotographic photosensitive member of the present invention, a high-performance and highly reliable image forming apparatus and a process unit for the image forming apparatus can be provided.

[Brief description of drawings]

FIG. 1 is a diagram of an example of an electrophotographic photoreceptor of the present invention.

FIG. 2 is a diagram of another example of the electrophotographic photosensitive member of the present invention.

FIG. 3 is a diagram of another example of the electrophotographic photosensitive member of the present invention.

FIG. 4 is a diagram of another example of the electrophotographic photosensitive member of the present invention.

FIG. 5 is a diagram showing still another example of the electrophotographic photosensitive member of the present invention.

FIG. 6 is a schematic view showing an example of an image forming apparatus of the present invention.

FIG. 7 is a schematic view showing an example of a process unit for an image forming apparatus of the present invention.

[Explanation of symbols]

31 conductive support 33 Photosensitive layer 35 Charge generation layer 37 Charge Transport Layer 39 Protective layer 101 photosensitive drum 102 charging device 103 exposure 104 developing device 105 transfer body 106 transfer device 107 cleaning blade

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Eiji Kurimoto             1-3-3 Nakamagome, Ota-ku, Tokyo Stocks             Company Ricoh (72) Inventor Nozomi Tamoto             1-3-3 Nakamagome, Ota-ku, Tokyo Stocks             Company Ricoh (72) Inventor Kojima Adult             1-3-3 Nakamagome, Ota-ku, Tokyo Stocks             Company Ricoh F-term (reference) 2H068 AA04 AA14 AA31 AA32 BA04                       BA12 CA33 EA04 FA03 FA27

Claims (7)

[Claims] 1. An electrophotographic photosensitive member comprising a conductive support and at least a photosensitive layer formed on the conductive support, wherein the outermost surface layer of the electrophotographic photosensitive member contains at least an inorganic filler and a binder resin. An electrophotographic photoreceptor, wherein the filler is a single crystal particle of α-alumina which is homogeneous and has no crystal seed inside. 2. The α-alumina particles are obtained by firing transition alumina as a raw material or an alumina raw material that becomes transition alumina by heat treatment in an atmosphere gas containing a hydrogen halide gas or an atmosphere gas into which a halogen gas and steam are introduced. The electrophotographic photosensitive member according to claim 1, which is manufactured by the above method. 3. The median particle diameter of the α-alumina particles is 0.
The electrophotographic photosensitive member according to claim 1, which has a thickness of 1 to 1 μm. 4. The α-alumina particles have a sodium content of 10 ppm% or less in terms of Na ₂ O and a purity of 99.95% by weight or more. The electrophotographic photoreceptor according to any one of the above. 5. The electrophotographic photosensitive member according to claim 1, wherein the outermost surface layer contains a polycarboxylic acid compound. 6. An image forming apparatus comprising a charging unit, an exposing unit, a developing unit, and a transferring unit in addition to the electrophotographic photosensitive member according to claim 1. 7. In addition to the electrophotographic photosensitive member according to claim 1, at least one unit selected from the group consisting of a charging unit, a developing unit, a transfer unit, a cleaning unit and a charge eliminating unit is integrated. A process unit for an image forming apparatus, characterized in that it is made detachable.