JP2022016937A - Electrophotographic photoreceptor and image forming apparatus including the same - Google Patents

Abstract

To provide an electrophotographic photoreceptor that is excellent in printing resistance, has high mechanical strength, and can prevent an image defect associated with chipping of an edge portion of a cleaning blade, and an image forming apparatus including the same.SOLUTION: The above-mentioned problem is solved by an electrophotographic photoreceptor comprising at least a laminated photosensitive layer that has a single-layer photosensitive layer containing a charge generating material and a charge transport material, or a charge generating layer containing the charge generating material and a charge transport layer containing the charge transport material laminated in this order on a conductive support. An outermost surface layer of the electrophotographic photoreceptor contains metal oxide-polymer composite particles.SELECTED DRAWING: Figure 1

Description

The present invention relates to an electrophotographic photosensitive member and an image forming apparatus including the electrophotographic photosensitive member. More specifically, the present invention comprises an electrophotographic photosensitive member having excellent printing resistance, high mechanical strength, and capable of suppressing image defects due to chipping of an edge portion of a cleaning blade (cleanability). Regarding the image forming apparatus.

In recent years, as an electrophotographic photosensitive member, an organic photosensitive member using an organic photoconducting material (in the present specification, also referred to as an "electrophotographic photosensitive member", simply referred to as a "photoreceptor") has been widely used.
However, due to the nature of the organic material, the organic photoconductor has a drawback that its surface is easily worn by rubbing such as a cleaning blade around the photoconductor.
On the other hand, with the recent increase in contact charging methods by roller charging and the extension of life, miniaturization and speeding up of electrophotographic devices such as digital copiers and printers, the surface of organic photoconductors is more likely to be worn. It is exposed to more severe conditions.
Therefore, as a means for overcoming the above-mentioned drawbacks, efforts have been made so far to improve the mechanical properties (wear resistance, printing resistance) of the material surface of the photoconductor.

Specifically, it is considered to add silica particles as a filler to the surface layer of the photoconductor. For example, Japanese Patent Application Laid-Open No. 2017-049519 (Patent Document 1) contains a charge generator as the photosensitive layer. A charge generating layer and a charge transporting layer arranged as a single layer and the outermost surface layer are provided, and the charge transporting layer contains a charge transporting agent, a binder resin, a phthalocyanine pigment and silica particles, and the content of the silica particles is a binder. Lamination in which 0.5 parts by mass or more and 15 parts by mass or less with respect to 100 parts by mass of the resin, the average primary particle size of the silica particles is 50 nm or more and 150 nm or less, and the surface of the silica particles is treated with hexamethyldisilazane. A type electrophotographic photosensitive member is disclosed.
Further, Japanese Patent Application Laid-Open No. 2001-066800 (Patent Document 2) describes an electrophotographic photosensitive member having at least a photosensitive layer on a conductive support, and the surface layer thereof has two specific repeating units and a siloxane structure. An electrophotographic photosensitive member containing a modified polycarbonate copolymer resin containing a repeating unit and containing silica fine particles having a volume average particle size of 0.005 μm or more and less than 0.05 μm is disclosed.

On the other hand, it has been considered to add polymer particles to the surface layer of the photoconductor. For example, Japanese Patent Application Laid-Open No. 7-295272 (Patent Document 3) describes an electrophotographic photosensitive member having a photosensitive layer on a conductive support. Yes, the surface layer contains a polymer having a specific structural unit A and a copolymer having a specific structural unit A and a specific structural unit B at the same time, and the number average particle size is 0.1 μm as a lubricant. An electrophotographic photosensitive member containing 2 to 30% by weight of a fluororesin-containing powder having a thickness of about 10 μm is disclosed.

Japanese Unexamined Patent Publication No. 2017-049519 Japanese Unexamined Patent Publication No. 2001-066800 Japanese Unexamined Patent Publication No. 7-295272

However, in the above-mentioned prior art, it is difficult to achieve both improvement in wear resistance of the surface of the photoconductor and good cleaning property.
In Patent Document 1, the photoconductor contains a metal oxide having a relatively large particle size (number average primary particle size of 50 nm or more) on its surface, and has a fine space on the surface of the cleaning blade and the photoconductor drum, so that it is wear resistant. Even if the properties are good, the cleaning blade is easily damaged by the metal oxide.
On the other hand, in Patent Document 2, since the photoconductor contains a metal oxide having a relatively small particle size (number average primary particle size less than 50 nm) on its surface and the fine particles are embedded in the surface of the photoconductor, it has wear resistance. Little effect is obtained.
Further, in Patent Document 3, the photoconductor contains a polymer having a relatively large particle size on its surface, and the polymer particles themselves are more easily worn or broken than the metal oxide, so that the effect of wear resistance is almost obtained. I can't.

Therefore, the present invention provides an electrophotographic photosensitive member having excellent printing resistance, high mechanical strength, and capable of suppressing image defects due to chipping of an edge portion of a cleaning blade, and an image forming apparatus provided with the same. The task is to do.

As a result of diligent research to solve the above problems, the present inventor has determined that the outermost surface layer of the photoconductor contains metal oxide-polymer composite particles having protrusions derived from metal oxide on the particle surface. The present invention has been completed by finding that both the improvement of the printing resistance of the photoconductor and the cleaning property can be achieved at the same time.

Thus, according to the present invention, on the conductive support, a single-layer photosensitive layer containing a charge generating substance and a charge transporting substance, or a charge containing a charge generating layer containing a charge generating substance and a charge transporting substance is charged. An electrophotographic photosensitive member including at least a laminated photosensitive layer in which a transport layer is laminated in this order.
Provided is an electrophotographic photosensitive member characterized in that the outermost surface layer of the electrophotographic photosensitive member contains metal oxide-polymer composite particles.

Further, according to the present invention, the above-mentioned electrophotographic photosensitive member, a charging means for charging the electrophotographic photosensitive member, and an exposure means for exposing the charged electrophotographic photosensitive member to form an electrostatic latent image. A developing means for developing the electrostatic latent image formed by exposure to form a toner image, a transfer means for transferring the toner image formed by development onto a recording medium, and the transferred toner image. Fixing means for fixing on the recording medium to form an image, cleaning means for removing and recovering toner remaining on the electrophotographic photosensitive member, and static elimination means for eliminating surface charge remaining on the electrophotographic photosensitive member. An image forming apparatus characterized by at least being provided is provided.

According to the present invention, there is provided an electrophotographic photosensitive member having excellent printing resistance, high mechanical strength, and capable of suppressing image defects due to chipping of an edge portion of a cleaning blade, and an image forming apparatus provided with the same. Can be offered to do.
The photoconductor of the present invention has a fine space on the surface of the cleaning blade and the photoconductor drum, and the metal oxide particles have an appropriate hardness, so that the wear resistance is good and the metal oxide particles are fine. Therefore, it is considered that image defects due to chipping of the edge portion of the cleaning blade hardly occur.
That is, the photoconductor of the present invention has an image that a part of the metal oxide-polymer composite particles contained in the outermost surface layer protrudes from the outermost surface layer, and by forming irregularities on the outermost surface layer. It is considered that the above-mentioned excellent effects are exhibited.

The photoconductor of the present invention more exerts the above-mentioned effect when any one of the following conditions (1) to (8) is satisfied.
(1) The metal oxide particles have a number average primary particle diameter of 10 to 30 nm.
(2) The metal oxide-polymer composite particles are in a form in which the metal oxide is exposed on the surface thereof.
(3) The metal oxide-polymer composite particle has a number average primary particle diameter of 130 to 300 nm.
(4) The single-layer type photosensitive layer and the charge transport layer contain a binder resin, and the metal oxide-polymer composite particles are contained in a ratio of 10 to 25 parts by mass with respect to 100 parts by mass of the binder resin. ..
(5) The outermost surface layer has a surface roughness Rz of 0.7 to 1.5 μm.
(6) The metal oxide is silica.
(7) The electrophotographic photosensitive member is a laminated electrophotographic photosensitive member having the laminated photosensitive layer.
(8) An undercoat layer is provided between the conductive support and the single-layer type photosensitive layer or the laminated type photosensitive layer.

It is a schematic sectional drawing which shows the structure of the main part of the photosensitive member (photoreceptor 1) of this invention. It is a schematic sectional drawing which shows the structure of the main part of the photosensitive member (photoreceptor 2) of this invention. It is a schematic sectional drawing which shows the structure of the main part of the photosensitive member (photoreceptor 3) of this invention. It is a schematic sectional drawing which shows the structure of the main part of the photosensitive member (photoreceptor 4) of this invention. It is a schematic side view which shows the structure of the main part of the image forming apparatus of this invention. Scanning electron micrographs (a) 100,000 times and (b) 200,000 times show an example of the dispersed state of the metal oxide-polymer composite particles in the outermost surface layer of the photoconductor of the present invention.

(1) Electrophotographic Photoreceptor The photoconductor of the present invention is a single-layer type photosensitive layer containing a charge-generating substance and a charge-transporting substance, or a charge-generating layer and a charge containing a charge-generating substance on a conductive support. An electrophotographic photosensitive member including at least a laminated photosensitive layer in which a charge transport layer containing a transport substance is laminated in this order.
The outermost surface layer of the electrophotographic photosensitive member is characterized by containing metal oxide-polymer composite particles.
Here, the outermost surface layer means a layer laminated on the outermost surface when viewed from the conductive support.
First, the metal oxide-polymer composite particles will be described, and then each configuration of the photoconductor will be described.

<Metal oxide-polymer composite particles>
The photoconductor of the present invention contains metal oxide-polymer composite particles in its outermost surface layer.
Metal oxides include silica (SiO ₂ ), alumina (Al ₂ O ₃ ), ceria (CeO ₂ ), molybdenum oxide (MoO ₃ ), titania (TIO ₂ ), zirconia (ZrO ₂ ), and zinc oxide (ZnO). , Iron oxide containing magnetic iron ore (Fe ₃ O ₄ ) and various forms of Fe ₂ O ₃ , niobium oxide (Nb ₂ O ₅ ), vanadium oxide (VO), tungsten oxide (WO ₂ ) and tin oxide (SnO). These can be used alone or as a mixture of two or more or as a mixed oxide. The chemical formulas in parentheses are typical oxide forms, and there are also oxide forms that differ depending on the valence of the metal atom, and these are included in the present invention.
Among the above oxides, silica, alumina and titania are preferable in terms of wear resistance, and silica is particularly preferable in terms of electrical characteristics.

When the metal oxide is silica, the metal oxide-polymer composite particle of the present invention can be produced, for example, by the method described in Examples of International Publication No. 2013/063291.
Specifically, first, the silica particles are treated with a first hydrophobizing agent containing the polymer group of the composite particles.
Examples of the hydrophobic agent include vinyltriacetoxysilane, (3-acrylicoxypropyl) trimethoxysilane, (3-acrylicoxypropyl) triethoxysilane, methacryloxypropyltrimethoxysilane, and methacryloxypropyltriethoxysilane. Acrylicoxypropyl) Methyldimethoxysilane, Methacyloxypropylmethyldimethoxysilane, Methacyloxypropyldimethylethoxysilane, Methacrylicoxypropyldimethylmethoxysilane, Allyltrimethoxysilane, Vinyltriethoxysilane, Vinyltrimethoxysilane, Vinyltris (2-methoxyethoxy) ) Silane and the like.

The treated silica particles are then treated with a monomer containing a polymerizable polymer group by the first hydrophobicizing agent and polymerized to give silica-polymer composite particles.
The polymer species used may be the same as or different from the first hydrophobicizing agent, but if the same material is used, it is easy to form a polymer. Further, different monomers copolymerizable with the terminal group of the first hydrophobicizing agent may be used.
Preferred monomers for use in producing metal oxide-polymer composite particles include substituted or unsubstituted vinyl and acrylate monomers, as well as other monomers polymerized by radical polymerization. It preferably contains styrene acrylates and methacrylates, olefins, vinyl esters, and acrylonitrile, and such monomers may be used alone or in admixtures to form copolymers, or with cross-linking agents.

The metal oxide particles of the present invention preferably have a number average primary particle diameter of 10 to 30 nm.
If the number average primary particle size is less than 10 nm, the effect of improving the wear resistance of the photoconductor may not be sufficiently obtained. On the other hand, if the number average primary particle diameter exceeds 30 nm, a state in which a part of the edge portion of the cleaning blade is chipped is likely to occur, and the residual toner cannot be sufficiently cleaned, causing streak-like defects in the printed image. Sometimes.
The more preferable number average primary particle diameter of the metal oxide particles is 16 to 25 nm.

The ratio M / P of the metal oxide (M) -polymer (P) composite particles is preferably 60/40 to 90/10.
If the ratio M / P is less than 60/40, a state in which a part of the edge portion of the cleaning blade is chipped is likely to occur, the residual toner cannot be sufficiently cleaned, and streak-like defects may be generated in the printed image. be. On the other hand, if the ratio M / P exceeds 90/10, the effect of improving wear resistance may not be sufficiently obtained.
A more preferable ratio M / P is 70/30 to 85/15.

The metal oxide-polymer composite particles of the present invention preferably have a number average primary particle diameter of 130 to 300 nm.
If the number average primary particle size is less than 130 nm, the effect of improving the wear resistance of the photoconductor may not be sufficiently obtained. On the other hand, if the number average primary particle diameter exceeds 300 nm, the cleaning property of the surface of the photoconductor by the cleaning blade deteriorates, and the toner component adheres to the surface of the photoconductor, which may cause defects on the image.
The number average primary particle size of the more preferable metal oxide-polymer composite particles is 145 to 170 nm.
The number average primary particle diameter here means that fine particles are magnified 30,000 to 300,000 times by observation with a scanning electron microscope, 100 particles are randomly observed as primary particles, and measurement is performed as the average diameter in the ferret direction by image analysis. It is a value, and the measuring method thereof will be described in Examples.

The outermost surface layer of the photoconductor of the present invention preferably has a surface roughness Rz of 0.7 to 1.5 μm.
If the surface roughness Rz is less than 0.7 μm, the effect of improving the wear resistance of the photoconductor may not be sufficiently obtained. On the other hand, if the surface roughness Rz exceeds 1.5 μm, a state in which a part of the edge portion of the cleaning blade is chipped is likely to occur, the residual toner cannot be sufficiently cleaned, and streak-like defects occur in the printed image. May cause you to.
A more preferable surface roughness Rz of the outermost surface layer is 0.9 to 1.1 nm.
This surface roughness Rz is an index of the state of protrusion of the metal oxide particles constituting the metal oxide-polymer composite particles in the outermost surface layer of the photoconductor, and is defined by JIS-B-0601 (1994). It can be measured based on the point average roughness Rz, and the measuring method thereof will be described in Examples.

The metal oxide-polymer composite particles are contained in the outermost surface layer, but are preferably dispersed in the outermost surface layer. That is, it is preferable that the metal oxide-polymer composite particles are independently present in the outermost surface layer, but a part of the metal oxide-polymer composite particles has a directional line of 0.2 to 1.0 μm. There is no problem even if an aggregate having a diameter (hereinafter, also referred to as “aggregate having a predetermined diameter”) is formed.
Here, the "constant tangential diameter" means the maximum distance between two parallel lines in contact with the aggregate. When the total number of metal oxide-polymer composite particles not forming aggregates and the aggregates thereof is 100, the number of aggregates is preferably less than 30, and preferably about 10 to 20. Is more preferable.

The number of metal oxide-polymer composite particles and their aggregates can be counted by, for example, the following method.
First, the outermost surface layer of the photoconductor, for example, the charge transport layer is peeled off from the photoconductor, and the peeled outermost surface layer is removed in the thickness direction by using a microtome device (manufactured by Leica Microsystems, Inc., model: UC7i). Cut along to prepare a section of the sample for measurement. Next, the obtained cross section is observed using a transmission electron detector of a scanning electron microscope (manufactured by Hitachi, Ltd., model: S-4800) with an acceleration voltage of 30 kV and no permanent contact. The number of aggregates having a directional tangential diameter of 0.2 to 1.0 μm and the number of metal oxide-polymer composite particles in the outermost surface layer in the cross-sectional image are counted.

FIG. 6 is a scanning electron micrograph showing an example of the dispersed state of the metal oxide-polymer composite particles in the outermost surface layer of the photoconductor of the present invention, in which (a) is 100,000 times and (b) is 200,000 times. be.
In FIG. 6, the portion shown in black is the metal oxide portion of the metal oxide-polymer composite particle. It can be seen that the polymer portion does not easily contrast with the binder of the photoconductor, but the portion that appears slightly black is the polymer portion, and the metal oxide is partially exposed on the surface of the polymer portion. By observing this image, the dispersed state of the metal oxide-polymer composite particles in the outermost surface layer can be confirmed.
As described above, the metal oxide-polymer composite particle is preferably in a form in which the metal oxide is exposed on the surface thereof.

The metal oxide-polymer composite particles are preferably contained in a ratio of 10 to 25 parts by mass with respect to 100 parts by mass of the binder resin constituting the outermost surface layer.
Here, the outermost surface layer is a case where the charge transport layer of the laminated photoconductor, which will be described later, the single layer type photosensitive layer of the single layer type photoconductor is the outermost surface layer of the photoconductor, and the photoconductor is provided with a surface protective layer. The surface protective layer becomes the outermost surface layer of the photoconductor.
If the content ratio of the metal oxide-polymer composite particles is less than 10 parts by mass with respect to 100 parts by mass of the binder resin, the effect of improving the wear resistance of the photoconductor may not be sufficiently obtained. On the other hand, if the content ratio of the metal oxide-polymer composite particles exceeds 25 parts by mass with respect to 100 parts by mass of the binder resin, the dispersibility is not sufficient, the agglomerates increase, and the cleaning property may deteriorate.
The content ratio of the more preferable metal oxide-polymer composite particles is 15 to 20 parts by mass.

<Photoreceptor>
The photoconductor of the present invention is a single-layer photosensitive layer containing a charge generating substance and a charge transporting substance, or a charge transporting layer containing a charge generating substance and a charge transporting substance on a conductive support. At least a laminated photosensitive layer in which the layers are laminated in this order is provided.
The photoconductor of the present invention will be described below with reference to the drawings, but the present invention is not limited thereto.

<Photoreceptor 1: Embodiment 1>
FIG. 1 is a schematic cross-sectional view showing the configuration of a main part of the photoconductor (photoreceptor 1) of the present invention.
The photoconductor 1 has an undercoat layer 18 provided on a conductive support 11, a charge generating layer 15 containing a charge generating substance 12 on the undercoat layer 18, a charge transporting substance 13, and a binder resin 17 for binding the charge transporting substance 13. A laminated photosensitive member ("" It is also called a "function-separated photoconductor").
In the present invention, the photoconductor is particularly preferably a laminated photoconductor having a laminated photoconductor.
Hereinafter, each configuration will be described.

<Conductive support 11>
The conductive support has a function as an electrode of the photoconductor and a function as a support member, and the constituent material thereof is not particularly limited as long as it is a material used in the art.
Specifically, for metal materials such as aluminum, aluminum alloys, copper, zinc, stainless steel and titanium, as well as conductive compounds such as metal foil laminates, metal vapor deposition treatments or conductive polymers, tin oxide and indium oxide on the surface. Examples include polymer materials such as polyethylene terephthalate, nylon and polystyrene, hard paper and glass, which have been vaporized or coated with layers. Among these, aluminum is preferable from the viewpoint of ease of processing, and aluminum alloys such as JIS3003 series, JIS5000 series and JIS6000 series are particularly preferable.
The shape of the conductive support is not limited to the cylindrical shape (drum shape) as shown in FIG. 5, and may be a sheet shape, a columnar shape, an endless belt shape, or the like.
In addition, the surface of the conductive support is treated with anodized film, surface-treated with chemicals or hot water, and colored to prevent interference fringes caused by laser light, if necessary, within a range that does not affect the image quality. It may be treated or subjected to diffuse reflection treatment such as roughening the surface.

<Underground layer (also called "middle layer") 18>

The photoconductor of the present invention preferably includes an undercoat layer 18 between the conductive support 11 and the photosensitive layer 14.
The undercoat layer generally covers the unevenness of the surface of the conductive support to make it uniform, thereby enhancing the film forming property of the photosensitive layer, here the charge generating layer, and suppressing the peeling of the photosensitive layer from the conductive support. Improves the adhesiveness between the conductive support and the photosensitive layer. Specifically, it is possible to prevent the injection of electric charge from the conductive support into the photosensitive layer, prevent the chargeability of the photosensitive layer from being lowered, and prevent image fogging (so-called black spots).

For the undercoat layer, for example, a binder resin is dissolved in an appropriate solvent to prepare a coating liquid for the undercoat layer, the coating liquid is applied to the surface of the conductive support, and the organic solvent is removed by drying. Can be formed.

Examples of the binder resin include natural polymer materials such as casein, gelatin, polyvinyl alcohol, and ethyl cellulose, in addition to the same binder resin as that contained in the photosensitive layer described later, and one or more of these may be used. Can be used.
The binder resin does not dissolve or swell with respect to the solvent used when forming the photoconductor layer on the undercoat layer, has excellent adhesion to the conductive support, and has flexibility. Among the above-mentioned binder resins, a polyamide resin is preferable, and an alcohol-soluble nylon resin is particularly preferable.
Examples of the alcohol-soluble nylon resin include homopolymerized or copolymerized nylons such as 6-nylon, 66-nylon, 610-nylon, 11-nylon and 12-nylon, and N-alkoxymethyl-modified nylons, which are chemically modified nylons. Examples thereof include a resin that has been specifically modified.

Examples of the solvent for dissolving or dispersing the resin material include alcohols such as water, methanol, ethanol and butanol, glime such as methylcarbitol and butylcarbitol, chlorine-based solvents such as dichloroethane, chloroform or trichloroethane, and acetone. Examples thereof include dioxolane and a mixed solvent in which two or more of these solvents are mixed. Among these solvents, non-halogen organic solvents are preferably used in consideration of the global environment.

Further, the coating liquid for the undercoat layer may contain the metal oxide particles 19.
The metal oxide particles can easily adjust the volume resistance value of the undercoat layer, further suppress the injection of electric charge into the photosensitive layer, and can maintain the electrical characteristics of the photoconductor under various environments.
Examples of the metal oxide particles include titanium oxide, aluminum oxide, aluminum hydroxide, tin oxide and the like.
The ratio (C / D) of the total weight C of the binder resin and the metal oxide particles and the weight D of the solvent in the coating liquid for the undercoat layer is preferably 1/99 to 40/60, and is preferably 2/98 to 30 /. 70 is particularly preferable.
The ratio E / F of the weight E of the binder resin and the weight F of the metal oxide particles is preferably 90/10 to 1/99, and particularly preferably 70/30 to 5/95.

Known devices such as ball mills, sand mills, attritors, vibration mills, ultrasonic dispersers and paint shakers may be used to disperse the metal oxide particles in the undercoat layer coating liquid.
As the coating method for the undercoat layer, the optimum method may be appropriately selected in consideration of the physical properties and productivity of the coating liquid, for example, the spray method, the bar coating method, the roll coating method, the blade method, and the like. Examples include a ring method and a dip coating method.
Among these, the dip coating method is a method of immersing the substrate in a coating tank filled with a coating liquid and then pulling it up at a constant speed or a sequentially changing speed to form a layer on the surface of the substrate, which is relatively relatively. Since it is simple and excellent in productivity and cost, it can be suitably used for manufacturing a photoconductor. In order to stabilize the dispersibility of the coating liquid, the apparatus used in the dip coating method may be provided with a coating liquid dispersion device typified by an ultrasonic wave generator.

The solvent in the coating film may be removed by natural drying, but the solvent in the coating film may be forcibly removed by heating.
The temperature in such a drying step is not particularly limited as long as it can remove the used solvent, but is appropriately about 50 to 140 ° C, and particularly preferably about 80 to 130 ° C.
If the drying temperature is less than 50 ° C., the drying time may be long, and the solvent may not evaporate sufficiently and may remain in the photoconductor layer. Further, if the drying temperature exceeds about 140 ° C., the electrical characteristics of the photoconductor during repeated use may deteriorate, and the obtained image may deteriorate.
Such temperature conditions are common not only in the undercoat layer but also in layer formation such as a photosensitive layer described later and other treatments.

The film thickness of the undercoat layer is not particularly limited, but is preferably 0.01 to 20 μm, and more preferably 0.05 to 10 μm.
If the film thickness of the undercoat layer is less than 0.01 μm, it will not function substantially as an undercoat layer, and it will not be possible to obtain uniform surface properties by covering the defects of the conductive support, and the conductive support will not be able to obtain uniform surface properties. It may not be possible to prevent the injection of electric charge into the photosensitive layer. On the other hand, if the film thickness of the undercoat layer exceeds 20 μm, it is difficult to form a uniform undercoat layer, and the sensitivity of the photoconductor may decrease.
When the constituent material of the conductive support is aluminum, a layer containing alumite (anodized layer) can be formed and used as an undercoat layer.

<Charge generation layer 15>
The charge generation layer has a function of generating charges by absorbing irradiated light such as semiconductor laser light in an image forming apparatus or the like, and has a charge generating substance as a main component, and a binder resin or an additive as necessary. Contains.

As the charge generating substance, compounds used in the art can be used, and specifically, azo pigments such as monoazo pigments, bisazo pigments and trisazo pigments; indigo pigments such as indigo and thioindigo; peryleneimide and perylene. Perylene pigments such as acid anhydrides; Polycyclic quinone pigments such as anthraquinone and pyrenequinone; Metallic phthalocyanines such as titanyl phthalocyanine and phthalocyanine pigments such as metal-free phthalocyanines; Examples thereof include organic photoconductive materials such as selenium and inorganic photoconductive materials such as selenium and amorphous silicon, and those having sensitivity in the exposure wavelength range can be appropriately selected and used. These charge generating substances may be used alone or in combination of two or more.
Among these charge generating substances, the following general formula (A):

(In the formula, X ¹ , X ² , X ³ and X ⁴ are the same or different, halogen atoms, alkyl groups or alkoxy groups, and r, s, y and z are the same or different 0-4. (It is an integer)
It is preferable to use titanylphthalocyanine represented by.
Titanylphthalocyanine is a charge generating substance having high charge generation efficiency and charge injection efficiency in the emission wavelength range (near infrared light) of laser light and LED light currently generally used, and absorbs light. Therefore, a large amount of electric charge can be generated, and the generated electric charge can be efficiently injected into the charge transporting material 13 without accumulating the generated electric charge inside.

The titanyl phthalocyanine represented by the general formula (A) is produced by a known production method such as Phthhalocyanine Compounds by Moser, Frank H and Arthur L. Thomas, Reinhold Publishing Corp., New York, 1963. can do.
For example, among the titanyl phthalocyanine compounds represented by the general formula (A), in the case of unsubstituted titanyl phthalocyanine in which r, s, y and z are 0, is phthalonitrile and titanium tetrachloride melted by heating? Alternatively, it can be obtained by synthesizing dichlorotitanylphthalocyanine by heating it in a suitable solvent such as α-chloronaphthalene and then hydrolyzing it with a base or water.
The titanyl phthalocyanine composition can also be produced by subjecting isoindoline and a titanium tetraalkoxide such as tetrabutoxytitanium to a heating reaction in a suitable solvent such as N-methylpyrrolidone.

As a method for forming the charge generating layer, a method of vacuum-depositing the charge generating substance on the conductive support and a coating liquid for the charge generating layer obtained by dispersing the charge generating substance in a solvent are applied on the conductive support. There is a method of applying. Among these, a method in which a charge generating substance is dispersed in a binder resin solution obtained by mixing a binder resin in a solvent by a conventionally known method and a coating liquid for a charge generating layer is applied onto a conductive support is used. preferable. Hereinafter, this method will be described.

The binder resin is not particularly limited, and any resin known in the art can be used, for example, polyester, polystyrene, polyurethane, phenol resin, alkyd resin, melamine resin, epoxy resin, silicone resin, acrylic resin, methacrylic resin. , Polycarbonate, polyarylate, polyphenoxy, polyvinyl butyral and polyvinylformal, and copolymer resins containing two or more of the repeating units constituting these resins.
Examples of the copolymer resin include insulating resins such as vinyl chloride-vinyl acetate copolymer resin, vinyl chloride-vinyl acetate-maleic anhydride copolymer resin and acrylonitrile-styrene copolymer resin. These resins may be used alone or in combination of two or more.

Solvents include, for example, halogenated hydrocarbons such as dichloromethane and dichloroethane, ketones such as acetone, methyl ethyl ketone and cyclohexanone, esters such as ethyl acetate and butyl acetate, ethers such as tetrahydrofuran (THF) and dioxane, 1, 2 -Alkyl ethers of ethylene glycol such as dimethoxyethane, aromatic hydrocarbons such as benzene, toluene and xylene, or aprotic polar solvents such as N, N-dimethylformamide and N, N-dimethylacetamide. .. These solvents may be used alone or in combination of two or more.

The blending ratio of the charge generating substance and the binder resin is preferably in the range of 10 to 99% by mass of the charge generating substance.
If the proportion of charge generating material is less than 10% by mass, the sensitivity may decrease. On the other hand, when the ratio of the charge generating substance exceeds 99% by mass, not only the film strength of the charge generating layer is lowered, but also the dispersibility of the charge generating substance is lowered and the coarse particles are increased, which should be erased by exposure. The surface charge other than the portion is reduced, and image defects, particularly fog of an image called black spots, in which toner adheres to a white background and minute black spots are formed, may occur.

Before the charge generating substance is dispersed in the binder resin solution, the charge generating substance may be pulverized in advance by a pulverizer. Examples of the crusher used for the crushing treatment include a ball mill, a sand mill, an attritor, a vibration mill, and an ultrasonic disperser.
Examples of the disperser used for dispersing the charge generating substance in the binder resin solution include a paint shaker, a ball mill, and a sand mill. As the dispersion conditions at this time, appropriate conditions may be selected so that impurities are not mixed due to wear of the container to be used and the members constituting the disperser.
Examples of the method for applying the coating liquid for the charge generation layer include the same method as the method for applying the coating liquid for the undercoat layer, and the dip coating method is particularly preferable.

The film thickness of the charge generation layer is not particularly limited, but is preferably 0.05 to 5 μm, and more preferably 0.1 to 1 μm.
If the film thickness of the charge generation layer is less than 0.05 μm, the efficiency of light absorption may decrease and the sensitivity of the photoconductor may decrease. On the other hand, if the film thickness of the charge generation layer exceeds 5 μm, the charge transfer inside the charge generation layer becomes a rate-determining step in the process of erasing the charge on the surface of the photosensitive layer, and the sensitivity of the photoconductor may decrease.

<Charge transport layer 16>
The charge transport layer has a function of receiving the charge generated by the charge generating substance and transporting it to the surface of the photoconductor, and contains a charge transporting substance, a binder resin, and an additive if necessary.
When the charge transport layer is the outermost surface layer of the photoconductor, it contains metal oxide-polymer composite particles.

As the charge transporting substance, compounds used in the art can be used.
Specifically, carbazole derivative, pyrene derivative, oxazole derivative, oxadiazole derivative, thiazole derivative, thiadiazole derivative, triazole derivative, imidazole derivative, imidazolone derivative, imidazolidine derivative, bisimidazolidine derivative, styryl compound, hydrazone compound, many. Ring aromatic compounds, indole derivatives, pyrazoline derivatives, oxazolone derivatives, benzimidazole derivatives, quinazoline derivatives, benzofuran derivatives, acridin derivatives, phenazine derivatives, aminostilben derivatives, triarylamine derivatives, triarylmethane derivatives, phenylenediamine derivatives, stillben derivatives , Butadiene derivative, enamine derivative, benzidine derivative, polymers having a group derived from these compounds in the main chain or side chain (poly-N-vinylcarbazole, poly-1-vinylpyrene, ethylcarbazole-formaldehyde resin, triphenylmethane Polymers, poly-9-vinyl anthracene, etc.), polysilanes, and the like. These charge transporting substances may be used alone or in combination of two or more.
Among these, stilbene derivatives, butadiene derivatives, enamine derivatives and those in which a plurality of these compounds are bonded are preferable.

Among these various charge transporting substances, compounds particularly preferable in terms of electrical properties, durability and chemical stability are exemplified below.

As a method for forming the charge transport layer, a charge transport substance is dispersed in a binder resin solution obtained by mixing a binder resin in a solvent by a conventionally known method, and a coating liquid for the charge transport layer is applied onto the charge generation layer. The method of coating is preferable. Hereinafter, this method will be described.

The binder resin is not particularly limited, and any resin known in the art can be used. For example, vinyl polymer resins such as polymethylmethacrylate, polystyrene and polyvinylchloride, copolymer resins thereof, and polycarbonates. Resins such as polyester, polyester carbonate, polysulfone, polyphenoxy, epoxy resin, silicone resin, polyarylate, polyphenylene oxide, polyamide, polyether, polyurethane, polyacrylamide, phenol resin, and heat curable by partially cross-linking these resins. Examples include resin. These binder resins can be used alone or in combination of two or more.
Among these, polystyrene, polycarbonate, polyarylate and polyphenylene oxide are preferable because they have a volume resistance value of 10 ¹³ Ω or more, are excellent in electrical insulation, and are also excellent in film forming property and potential characteristics, and polycarbonate is particularly preferable. ..

The ratio A / B of the charge transporting substance (A) and the binder resin (B) is preferably 10/12 to 10/30.
When the ratio A / B is less than 10/30 and the ratio of the binder resin is high, when the charge transport layer is formed by the dip coating method, the viscosity of the coating liquid increases, which causes a decrease in the coating speed and the productivity is significantly deteriorated. Become. Further, if the amount of the solvent in the coating liquid is increased in order to suppress the increase in the viscosity of the coating liquid, a brushing phenomenon may occur and cloudiness may occur in the formed charge transport layer. On the other hand, when the ratio A / B exceeds 10/12 and the ratio of the binder resin is low, the printing durability is low as compared with the case where the ratio of the binder resin is high, and the amount of wear of the photosensitive layer may increase.

The charge transport layer may contain additives such as a plasticizer or a leveling agent, if necessary, in order to improve film forming property, flexibility and surface smoothness.
Examples of the plasticizer include dibasic acid esters such as phthalates, fatty acid esters, phosphoric acid esters, chlorinated paraffins and epoxy-type plasticizers.
Examples of the leveling agent include silicone-based leveling agents.
Further, the charge transport layer may contain fine particles of an inorganic compound or an organic compound in order to enhance mechanical strength and improve electrical characteristics.

Solvents include aromatic hydrocarbons such as benzene, toluene, xylene and monochlorobenzene, halogenated hydrocarbons such as dichloromethane and dichloroethane, ethers such as THF, dioxane and dimethoxymethyl ethers, and N, N-dimethylformamide and the like. Examples include an aprotic polar solvent. Further, if necessary, a solvent such as alcohols, acetonitrile or methyl ethyl ketone can be further added and used. Among these solvents, non-halogen organic solvents are preferably used in consideration of the global environment. These solvents may be used alone or in combination of two or more.

In the charge transport layer, for example, the charge transport substance 13 and the binder resin 17 and, if necessary, the above-mentioned additives are dissolved or dispersed in a suitable solvent in the same manner as in the case of forming the above-mentioned charge generation layer 15. A coating liquid for a charge transport layer is prepared, and the coating liquid is applied onto the charge generation layer 15 by a spray method, a bar coating method, a roll coating method, a blade method, a ring method, a dip coating method, or the like. To. Among these coating methods, the immersion coating method is particularly excellent in various points as described above, and is therefore often used when forming a charge transport layer.

The film thickness of the charge transport layer is not particularly limited, but is preferably 5 to 50 μm, more preferably 10 to 40 μm.
If the film thickness of the charge transport layer is less than 5 μm, the charge retention ability of the surface of the photoconductor may decrease. On the other hand, if the film thickness of the charge transport layer exceeds 50 μm, the resolution of the photoconductor may decrease.

<Photoreceptor 2: Embodiment 2>
FIG. 2 is a schematic cross-sectional view showing the configuration of a main part of the photoconductor (photoreceptor 2) of the present invention.
The photoconductor 2 has a charge generation layer 18 on which an undercoat layer 18 is provided on the conductive support 11, and a charge generation substance 12, a charge transport material 13, and a binder resin 17 for binding the charge generation substance 12 and a binder resin 17 for binding the charge generation substance 12 and the charge transport material 13 are provided therein. It is a single-layer type photosensitive member provided with a single-layer type photosensitive layer (also referred to as “single-layer type photosensitive layer”) 14 having a function as a charge transport layer.
When the single-layer type photosensitive layer is the outermost surface layer of the photoconductor, it contains metal oxide-polymer composite particles.

The single-layer photosensitive layer is formed in the same manner as in the case of forming the charge transport layer. For example, a charge generating substance, a charge transporting substance, a binder resin, and a metal oxide-polymer composite particle are dissolved or dispersed in an appropriate solvent to prepare a coating liquid for a photosensitive layer, and the coating liquid for a photosensitive layer is immersed and coated. It is formed by applying it on the undercoat layer by such means.
The single-layer type photosensitive layer may contain an appropriate amount of the same additives as those contained in the charge generation layer, if necessary, as long as the effects of the present invention are not impaired.

The ratio of the charge transporting substance 13 and the binder resin 17 in the photosensitive layer is 10/12 to 10/12 by weight, similar to the ratio A / B of the charge transporting substance 13 and the binder resin 17 in the charge transporting layer 16 described above. It is 10/30.

The film thickness of the single-layer type photosensitive layer is not particularly limited, but is preferably 5 to 100 μm, and more preferably 10 to 50 μm.
If the film thickness of the single-layer type photosensitive layer is less than 5 μm, the charge retention ability of the surface of the photoconductor may decrease. On the other hand, if the film thickness of the single-layer type photosensitive layer exceeds 100 μm, the productivity in manufacturing the photoconductor may decrease.

<Surface protective layer 20>
As shown in FIGS. 3 and 4, the photoconductor of the present invention may have a surface protective layer on the photosensitive layer.
3 and 4 are schematic cross-sectional views showing the configuration of the main parts of the photoconductors 3 and 4 (embodiments 3 and 4) of the present invention, respectively, of FIGS. 1 and 2, respectively. It is a photoconductor having a surface protective layer 20 on the photosensitive layer 14 (outermost layer).
The surface protective layer has a function of improving the durability of the photoconductor, and contains a binder resin and, if necessary, an additive. Further, the surface protective layer may contain one or more of the same charge transporting substances as the charge transporting layer in order to stabilize the electrical characteristics.
When the photoconductor has a surface protection layer, the surface protection layer becomes the outermost surface layer of the photoconductor and contains a predetermined amount of metal oxide-polymer composite particles with respect to the binder resin constituting the surface protection layer.

As the binder resin, a resin having binding properties used in the art can be used, and examples thereof include resins such as polystyrene, polyacetal, polyethylene, polycarbonate, polyallylate, polysulfone, polypropylene, and polyvinyl chloride. These binder resins may be used alone or in combination of two or more.
Among these, polycarbonate and polyarylate are particularly preferable in consideration of wear characteristics and electrical characteristics.

Further, a filler material may be added to the surface protective layer for the purpose of improving wear resistance.
Examples of the organic filler material include fluororesin powder such as polytetrafluoroethylene, silicone resin powder, a-carbon powder and the like, and examples of the inorganic filler material include metal powder such as copper, tin, aluminum and indium. Examples thereof include silica, tin oxide, zinc oxide, titanium oxide, indium oxide, antimony oxide, bismuth oxide, antimony-doped tin oxide, tin-doped metal oxides such as indium oxide, and inorganic materials such as potassium titanate. Inorganic filler materials are particularly preferred in terms of filler hardness.
The average primary particle size of the filler is preferably 0.01 to 0.5 μm from the viewpoint of light transmittance and wear resistance of the surface protective layer.

Further, the filler material may be surface-treated with an inorganic substance or an organic substance from the viewpoint of improving the dispersibility in the coating liquid for forming the coating. For example, water-repellent treatments include those treated with a silane coupling agent, those treated with a fluorine-based silane coupling agent, those treated with a higher fatty acid, and those whose filler surface is treated with alumina, zirconia, tin oxide, and silica. Be done.
The higher the content ratio of the filler material in the surface protective layer, the better the wear resistance, but if it is too high, adverse effects such as an increase in the residual potential and a decrease in the write light transmittance of the surface protective layer may occur. be. Therefore, the filler material is approximately 50% by weight or less, preferably 30% by weight or less, based on the total solid content.

The film thickness of the surface protective layer is not particularly limited, but is preferably 0.1 to 10 μm, and more preferably 1.0 to 8.0 μm.
Photoreceptors that are used repeatedly over a long period of time are designed to be mechanically durable and resistant to wear. However, in the actual machine, ozone, NOx gas, and the like are generated from the charging member and the like and adhere to the surface of the photoconductor to generate an image flow. In order to prevent this image flow, it is necessary to wear the photosensitive layer at a certain speed or higher, and considering long-term repeated use, the surface protective layer preferably has a film thickness of at least 1.0 μm or more. Further, if the film thickness of the surface protective layer exceeds 8.0 μm, problems such as an increase in residual potential and a decrease in fine dot reproducibility may occur.

(2) Image forming apparatus 100
The image forming apparatus of the present invention includes the photoconductor of the present invention, a charging means for charging the photoconductor, an exposure means for exposing the charged photoconductor to form an electrostatic latent image, and a static electricity formed by exposure. A developing means for developing an electro-latent image to form (visualize) a toner image, a transfer means for transferring the toner image formed by development onto a recording medium, and a transfer means for transferring the transferred toner image onto a recording medium. It is characterized by having at least a fixing means for fixing to the image to form an image, a cleaning means for removing and recovering toner remaining on the photoconductor, and a static electricity removing means for removing static electricity on the surface charge remaining on the photoconductor.
The image forming apparatus of the present invention and its operation will be described with reference to the drawings, but the present invention is not limited to the following description.

FIG. 5 is a schematic side view showing the configuration of the image forming apparatus of the present invention.
The image forming apparatus (laser printer) 100 of FIG. 5 includes a photoconductor 1, an exposure means (semiconductor laser) 31, a charging means (charger) 32, a developing means (developer) 33, and a transfer means of the present invention. A (transfer charger) 34, a transport belt (not shown), a fixing means (fixing device) 35, and a cleaning means (cleaner) 36 are included. Reference numeral 51 indicates a recording medium (recording paper or transfer paper).

The photoconductor 1 is rotatably supported by the main body of the image forming apparatus 100, and is rotationally driven in the direction of the arrow 41 around the rotation axis 44 by a driving means (not shown). The driving means includes, for example, an electric motor and a reduction gear, and by transmitting the driving force to the conductive support constituting the core body of the photoconductor 1, the photoconductor 1 is rotationally driven at a predetermined peripheral speed. .. The charging means (charger) 32, the exposure means 31, the developing means (developer) 33, the transfer means (transfer charger) 34, and the cleaning means (cleaner) 36 are in this order along the outer peripheral surface of the photoconductor 1. , It is provided from the upstream side to the downstream side in the rotation direction of the photoconductor 1 indicated by the arrow 41.

The charger 32 is a charging means for uniformly charging the outer peripheral surface of the photoconductor 1 to a predetermined potential.
The exposure means 31 includes a semiconductor laser as a light source, and is charged by irradiating the surface of the photoconductor 1 between the charger 32 and the developer 33 with the laser beam light output from the light source. The outer peripheral surface of the laser is exposed according to the image information. The light is repeatedly scanned in the direction in which the rotation axis 44 of the photoconductor 1 extends, which is the main scanning direction, and these are imaged to sequentially form an electrostatic latent image on the surface of the photoconductor 1. That is, the charged amount of the photoconductor 1 uniformly charged by the charger 32 differs depending on whether the laser beam is irradiated or not, and an electrostatic latent image is formed.

The developer 33 is a developing means for developing an electrostatic latent image formed on the surface of the photoconductor 1 by exposure with a developer (toner), and is provided facing the photoconductor 1 and has an outer peripheral surface of the photoconductor 1. A developing roller 33a that supplies toner to the processing roller 33a, and a casing 33b that rotatably supports the developing roller 33a around a rotating axis parallel to the rotating axis 44 of the photoconductor 1 and stores a developer containing toner in its internal space. Be prepared.

The transfer charger 34 supplies a toner image, which is a visible image formed on the outer peripheral surface of the photoconductor 1 by development, between the photoconductor 1 and the transfer charger 34 from the direction of the arrow 42 by a transport means (not shown). It is a transfer means for transferring onto a transfer paper 51 which is a recording medium. The transfer charging device 34 is, for example, a contact-type transfer means that includes charging means and transfers a toner image onto the transfer paper 51 by applying a charge having a polarity opposite to that of the toner on the transfer paper 51.

The cleaner 36 is a cleaning means for removing and recovering the toner remaining on the outer peripheral surface of the photoconductor 1 after the transfer operation by the transfer charger 34, and the cleaning blade 36a for peeling off the toner remaining on the outer peripheral surface of the photoconductor 1. A recovery casing 36b for accommodating the toner peeled off by the cleaning blade 36a is provided. Further, the cleaner 36 is provided together with a static elimination lamp (not shown).

Further, the image forming apparatus 100 is provided with a fixing device 35, which is a fixing means for fixing the transferred image, on the downstream side where the transfer paper 51 that has passed between the photoconductor 1 and the transfer charging device 34 is conveyed. Be done. The fuser 35 includes a heating roller 35a having a heating means (not shown), and a pressure roller 35b provided facing the heating roller 35a and pressed by the heating roller 35a to form a contact portion.
Reference numeral 37 indicates a separating means for separating the transfer paper and the photoconductor, and reference numeral 38 indicates a casing accommodating the above-mentioned means of the image forming apparatus.

The image forming operation by the image forming apparatus 100 is performed as follows.
First, when the photoconductor 1 is rotationally driven in the direction of the arrow 41 by the driving means, the photoconductor 1 is driven by the charger 32 provided on the upstream side of the photoconductor 1 in the rotational direction with respect to the image formation point of the light by the exposure means 31. The surface of the surface is uniformly charged to a positive predetermined potential.

Next, the exposure means 31 irradiates the surface of the photoconductor 1 with light according to the image information. In the photoconductor 1, the surface charge of the portion irradiated with light is removed by this exposure, and a difference occurs between the surface potential of the portion irradiated with light and the surface potential of the portion not irradiated with light, resulting in electrostatic capacitance. A latent image is formed.
Toner is supplied to the surface of the photoconductor 1 on which the electrostatic latent image is formed from the developing device 33 provided on the downstream side in the rotation direction of the photoconductor 1 from the image forming point of the light by the exposure means 31, and the electrostatic latent image is formed. Is developed and a toner image is formed.

The transfer paper 51 is supplied between the photoconductor 1 and the transfer charger 34 in synchronization with the exposure to the photoconductor 1. A charge having a polarity opposite to that of the toner is applied to the supplied transfer paper 51 by the transfer charger 34, and the toner image formed on the surface of the photoconductor 1 is transferred onto the transfer paper 51.
The transfer paper 51 to which the toner image is transferred is conveyed to the fixing device 35 by the conveying means, and is heated and pressurized when passing through the abutting portion between the heating roller 35a and the pressure roller 35b of the fixing device 35, and the toner is transferred. The image is fixed on the transfer paper 51 to obtain a robust image. The transfer paper 51 on which the image is formed in this way is discharged to the outside of the image forming apparatus 100 by the conveying means.

On the other hand, the toner remaining on the surface of the photoconductor 1 even after the toner image is transferred by the transfer charger 34 is peeled off from the surface of the photoconductor 1 by the cleaner 36 and recovered. The electric charge on the surface of the photoconductor 1 from which the toner has been removed in this manner is removed by the light from the static elimination lamp, and the electrostatic latent image on the surface of the photoconductor 1 disappears. After that, the photoconductor 1 is further rotationally driven, and a series of operations starting from charging are repeated to continuously form an image.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.
In Examples and Comparative Examples, a laminated photoconductor provided with a laminated photosensitive layer was adopted, but the same effect can be obtained by using a single-layer photosensitive member provided with a single-layer photosensitive layer.
The number average primary particle diameter of the metal oxide particles and the metal oxide-polymer composite particles used in Examples and Comparative Examples, and the surface roughness Rz of the outermost surface layer (charge transport layer) of the photoconductor were set as follows. Was measured.

[Number average primary particle diameter of metal oxide particles and metal oxide-polymer composite particles]
Metal oxide particles and metal oxide-polymer composite particles are magnified 30,000 to 300,000 times by scanning electron microscopy, 100 particles are randomly observed as primary particles, and measured as the average diameter in the ferret direction by image analysis. The value was taken as the number average primary particle size (nm).
Specifically, it was observed with a transmission electron detector of a scanning electron microscope (manufactured by Hitachi, Ltd., model: S-4800) with an acceleration voltage of 30 kV and no permanent contact. The magnification was an observable magnification depending on the particle size of the metal oxide particles and the metal oxide-polymer composite particles. 100 particles were randomly observed on the image as primary particles, the diameter in the ferret direction was measured, an average value was calculated, and this was taken as the number average primary particle size.

[Surface roughness Rz of the outermost surface layer (charge transport layer) of the photoconductor]
The state of protrusion of the metal oxide particles constituting the metal oxide-polymer composite particles in the outermost surface layer of the photoconductor was confirmed by the surface roughness of the outermost surface layer of the photoconductor. As an index showing the surface roughness, the ten-point average roughness Rz defined in JIS-B-0601 (1994) was used. That is, in the portion extracted from the cross-sectional curve of the photoconductor by the reference length, the average of the elevations of the highest to fifth peaks measured in the direction perpendicular to the average line from the straight line parallel to the average line and not crossing the cross-section curve. The value expressed in μm as the difference between the value and the average value of the elevations of the valley bottoms from the deepest to the fifth was used.
Specifically, using a surface roughness measuring device (manufactured by Tokyo Precision Co., Ltd., model: Surfcom1400D), the reference length is 0.8 mm, the cutoff wavelength is 0.8 mm, the measurement speed is 0.1 mm / sec, and the cutoff type. The surface roughness Rz (μm) was measured by the Gaussian method with the measurement position as the central portion in the axial direction of the photoconductor.

(Example 1)
Titanium oxide (manufactured by Ishihara Sangyo Co., Ltd., trade name: Tybake TTO-D-1) 3 parts by mass and copolymerized polyamide (nylon) (manufactured by Toray Co., Ltd., trade name: Amylan (registered trademark), grade: CM8000) 2 mass The parts were added to 25 parts by mass of methyl alcohol and dispersed with a paint shaker for 8 hours to prepare 3 liters of a coating liquid for an undercoat layer.
The coating layer is filled with the obtained coating liquid for the undercoat layer, and an aluminum drum-shaped support having a diameter of 30 mm and a length of 255 mm is immersed as the conductive support 11 and then pulled up, and the obtained coating film is naturally dried. Therefore, an undercoat layer 18 having a film thickness of 1 μm was formed on the conductive support 11.

In advance, titanylphthalocyanine represented by the following structural formula to be used as a charge generating substance was prepared.

29.2 g of diiminoisoindoline and 200 ml of sulfolane were mixed, 17.0 g of titanium tetraisopropoxide was further added, and the mixture was reacted at 140 ° C. for 2 hours under a nitrogen atmosphere. After allowing the obtained reaction mixture to cool, the precipitate was collected by filtration, washed successively with chloroform and a 2% aqueous solution of hydrochloric acid, washed successively with water and methanol, and dried to obtain 25.5 g of bluish-purple crystals. Got
As a result of chemical analysis of the obtained compound, it was confirmed that it was titanylphthalocyanine represented by the above structural formula (yield 88.5%).
1 part by mass of the obtained titanylphthalocyanine and 1 part by mass of butyral resin (manufactured by Denki Kagaku Kogyo Co., Ltd., trade name: BM-2) were added to 98 parts by mass of methyl ethyl ketone and dispersed for 2 hours with a paint shaker to generate charge. 3 liters of coating solution for layers was prepared.
The obtained coating liquid for the charge generation layer is applied onto the undercoat layer by the same dipping method as in the case of forming the undercoat layer, and the obtained coating film is naturally dried to obtain a charge having a film thickness of 0.3 μm. A developmental layer was formed.

Next, silica-polymer composite particles were used as the metal oxide-polymer composite particles, based on the description of Example 1 of International Publication No. 2013/063291, colloidal silica (number average primary particle size 25 nm, manufactured by SIGMA-ALDRICH). Product name: LUDOX (registered trademark) AS-40) was used.
63 g of the obtained silica-polymer composite particles (number average primary particle size 145 nm), N, N'-diphenyl-N, N'-di (m-tolyl) benzidine (manufactured by Tokyo Kasei Kogyo Co., Ltd.) as a charge transport material. Code: D2448) 250 g and polycarbonate (manufactured by Teijin Chemicals Ltd., trade name: TS2050) 375 g were added to 2725 g of tetrahydrofuran, mixed, and stirred with a ball mill for 15 hours. The obtained mixture was subjected to 1Pass dispersion treatment using a particle disperser (manufactured by Microfluidics, model: M-110P) to prepare 3243 g of a coating liquid for a charge transport layer.
The obtained coating liquid for the charge transport layer is applied onto the charge generating layer by the same dipping method as in the case of forming the undercoat layer, and the obtained coating film is dried at 120 ° C. for 1 hour to have a film thickness of 30 μm. The charge transport layer of No. 1 was formed, and the photoconductor shown in FIG. 1 was obtained.
When the cross section of the obtained photoconductor was observed, the number of aggregates of the silica-polymer composite particles was 15 out of 100 silica-polymer composite particles.

(Example 2)
In the preparation of the coating liquid for the charge transport layer, colloidal silica (number average primary particle size 25 nm, manufactured by SIGMA-ALDRICH, trade name: LUDOX® AS-40) is replaced with colloidal silica (number average primary particle size). The photoconductor was prepared in the same manner as in Example 1 except that silica-polymer composite particles (number average primary particle size 135 nm) produced using 10 nm, manufactured by Nissan Chemical Co., Ltd., trade name: Snowtex OS) were used. Made.

(Example 3)
A photoconductor was prepared in the same manner as in Example 1 except that the silica-polymer composite particles (number average primary particle size 145 nm) were changed from 63 g to 40 g in the preparation of the coating liquid for the charge transport layer.

(Example 4)
A photoconductor was prepared in the same manner as in Example 1 except that the silica-polymer composite particles (number average primary particle size 145 nm) were changed from 63 g to 90 g in the preparation of the coating liquid for the charge transport layer.

(Example 5)
In the preparation of the coating liquid for the charge transport layer, the silica-polymer composite particles prepared based on the description of Example 12 of International Publication No. 2013/063291 instead of the silica-polymer composite particles (number average primary particle size 145 nm). A photoconductor was prepared in the same manner as in Example 1 except that (number average primary particle size 262 nm) was used.

(Example 6)
In the preparation of the coating liquid for the charge transport layer, colloidal silica (number average primary particle size 25 nm, manufactured by SIGMA-ALDRICH, trade name: LUDOX® AS-40) is replaced with colloidal silica (number average primary particle size). The photoconductor was prepared in the same manner as in Example 1 except that silica-polymer composite particles (number average primary particle size 168 nm) produced using 40 nm, manufactured by Nissan Chemical Co., Ltd., trade name: Snowtex OL) were used. Made.

(Example 7)
A photoconductor was prepared in the same manner as in Example 1 except that the silica-polymer composite particles (number average primary particle size 145 nm) were changed from 63 g to 30 g in the preparation of the coating liquid for the charge transport layer.

(Example 8)
A photoconductor was prepared in the same manner as in Example 1 except that the silica-polymer composite particles (number average primary particle size 145 nm) were changed from 63 g to 120 g in the preparation of the coating liquid for the charge transport layer.

(Example 9)
In the preparation of the coating liquid for the charge transport layer, the silica-polymer composite particles prepared based on the description of Example 16 of International Publication No. 2013/063291 instead of the silica-polymer composite particles (number average primary particle size 145 nm). A photoconductor was prepared in the same manner as in Example 1 except that (number average primary particle size 360 nm) was used.

(Example 10)
In the preparation of the coating liquid for the charge transport layer, the silica-polymer composite particles (number average primary particle size) produced in 2 hours, which is 1 hour shorter than the reaction time of 3 hours described in Example 1 of International Publication No. 2013/063291. A photoconductor was prepared in the same manner as in Example 1 except that 120 nm) was used.

(Comparative Example 1)
A photoconductor was prepared in the same manner as in Example 1 except that silica-polymer composite particles were not used in the preparation of the coating liquid for the charge transport layer.

(Comparative Example 2)
Other than the use of silica particles (number average primary particle size 16 nm, manufactured by Nippon Aerosil Co., Ltd., trade name: AEROSIL® 130) instead of silica-polymer composite particles in the preparation of the coating liquid for the charge transport layer. Made a photoconductor in the same manner as in Example 1.

(Comparative Example 3)
In the preparation of the coating liquid for the charge transport layer, it was carried out except that silica particles (number average primary particle size 300 nm, manufactured by Admatex Co., Ltd., trade name: SO-E1) were used instead of the silica-polymer composite particles. A photoconductor was prepared in the same manner as in Example 1.

(Comparative Example 4)
In the preparation of the coating liquid for the charge transport layer, it was carried out except that resin particles (number average primary particle size 150 nm, manufactured by Soken Chemical Co., Ltd., trade name: MP-1451) were used instead of the silica-polymer composite particles. A photoconductor was prepared in the same manner as in Example 1.

[evaluation]
The photoconductors obtained in Examples 1 to 10 and Comparative Examples 1 to 4 were mounted on a unit of a digital copying machine (manufactured by Sharp Corporation, model: MX-B455W) modified for testing, and 300,000 images were obtained. By forming, the printing durability and the cleaning property were evaluated as follows.

[Print resistance]
The cleaning blade of the cleaning device provided in the digital multifunction device adjusted the pressure in contact with the photoconductor, the so-called cleaning blade pressure, to 21 gf / cm (2.06 × 10 ^-1 N / cm: initial linear pressure). A print resistance test is performed by printing a character test chart (ISO19752) on 300,000 sheets of recording paper under a normal temperature / normal humidity (N / N: Normal Temperature / Normal Humidity) environment with a temperature of 25 ° C. and a humidity of 50%. rice field.
The thickness of the photosensitive layer at the start of the printing resistance test and after the formation of 300,000 images was measured using a film thickness measuring device (manufactured by Philmetrics, model: F-20-EXR).
From the difference between the film thickness at the start of the printing endurance test and the film thickness after forming 300,000 images, the amount of scraping per 100,000 rotations of the photoconductor drum is obtained, and the amount of scraping obtained is based on the following criteria. The printability was evaluated.
It was evaluated that the larger the amount of scraping, the worse the printing durability.

<Judgment criteria>
A: Shaving amount <0.50 μm / 100,000 rotations Can be used without problems even in multifunction devices or printers that require long life B: 0.50 μm / 100,000 rotations ≤ Shaving amount <0.70 μm / 100,000 rotations Shaving amount Although it is a little large, it can be used without problems if it is not a multifunction device or printer that requires a long life. C: 0.70 μm / 100,000 rotations ≤ scraping amount <0.85 μm / 100,000 rpm Can be used without problems if it is a multifunction device or printer D: Shaving amount ≤ 0.85 μm / 100,000 rotations Shaving amount is large and there is a problem in practical use

[Cleanability]
In order to confirm the level of cleaning failure of the photoconductor after the printing resistance test, set the photoconductor after forming 300,000 images on a digital copier (manufactured by Sharp Corporation, model: MX-B455W) and put it on A4 paper. One 100% density untransferred image is output, immediately after that, the image forming apparatus is forcibly stopped, the surface of the photoconductor is visually observed, and the degree of cleaning failure is based on the following criteria from the observation results. Was evaluated.

<Judgment criteria>
A: No cleaning defects occur Can be used without problems in multifunction devices or printers that require high image quality B: 1 or 2 cleaning defects can be used without problems except for multifunction devices or printers that require high image quality Possible C: There are 3 to 5 cleaning defects. Can be used without problems if it is an inexpensive multifunction device or printer. D: There are many cleaning defects. There are problems in actual use.

<Comprehensive evaluation>
Based on the judgment result of the above evaluation, the photoconductor was comprehensively evaluated according to the following criteria.
A: Very good Can be used without problems even in multifunction devices or printers that require long life and high image quality B: There are no C or D judgments for either printing durability or cleanability, and either one is B judgment long life And it can be used without problems if it is not a multifunction device or printer that requires high image quality. Can be used without problems D: Either printing resistance or cleaning property is judged as D. Actually unusable The obtained results are shown together with the material, physical properties and surface condition of the metal oxide-polymer composite particles of the outermost surface layer of the photoconductor. Shown in 1.

From the results in Table 1, the following can be seen.
(1) The photoconductors (Examples 1 to 10) in which the charge transport layer contains silica-polymer composite particles as the metal oxide-polymer composite particles include a photoconductor not containing the composite particles (Comparative Example 1) and silica. Compared with the photoconductors containing particles (Comparative Examples 2 and 3) and the photoconductors containing polymer particles (Example 4), it is possible to achieve both improvement in printing durability and suppression of the occurrence of cleaning defects (2) Silica-polymer composite. Number of Silica Particles The photoconductor (Example 2) having an average primary particle diameter of 10 nm can be used without problems except for a compound machine or a printer that requires a long life, although the amount of scraping is slightly large (Example 2). 3) Number of Silica Particles of Silica-Polymer Composite Particles The photoconductor (Example 6) having an average primary particle diameter of 40 nm is slightly inferior in cleanability, but is not a compound machine or a printer that requires high image quality. , Can be used without problems

(4) Photoreceptors (Examples 5 and 9) containing silica-polymer composite particles having a relatively large number average primary particle size tend to have poor cleanability, but are better if they are 300 nm or less. (5) Photoconductors (Examples 2 and 10) containing silica-polymer composite particles having a relatively small number average primary particle diameter tend to have a large amount of scraping, but are better if they are 130 nm or more. (6) Abrasion resistance tends to deteriorate when the content of the silica-polymer composite particles is low (Examples 3 and 7), and cleaning property tends to deteriorate when the content is high (Example 4). And 8), it is better if the addition amount is 10 to 30 parts by mass with respect to 100 parts by mass of the binder resin. (7) The surface roughness Rz of the outermost surface layer of the photoconductor is 0.7 to 1.5 μm. The photoconductors (Examples 1 to 7) have better cleaning properties than the photoconductors (Examples 8 and 9) having a surface roughness Rz of more than 1.5 μm, and the surface roughness Rz is 0. . Good with less scraping compared to photoconductors smaller than 7 μm (Examples 7 and 10).

(8) The photoconductor containing silica particles having a relatively small number average primary particle size (Comparative Example 2) has good cleanability but is inferior in printing resistance, and silica particles having a relatively large number average primary particle size. Although the photoconductor containing the above (Comparative Example 3) has good printing resistance, the cleaning property is remarkably poor, which causes a problem in actual use. This is because the adhesion between the photoconductor and the cleaning blade is poor when the silica particles are small. Further, it is considered that the printing resistance is deteriorated, and if the particle size of the silica particles is large, the cleaning blade is chipped and the cleaning property is deteriorated.
(9) The photoconductor containing the polymer particles (Comparative Example 4) has good cleaning properties but is inferior in printing resistance, which causes a problem in actual use. It is considered that this is because the polymer particles themselves can be scraped.

1, 2, 3, 4 Electrophotograph photosensitive member 11 Conductive support 12 Charge generating substance 13 Charge transporting substance 14 Photosensitive layer 15 Charge generating layer 16 Charge transporting layer 17 Binder resin (binding resin)
18 Undercoat layer (middle layer)
19 Metal oxide particles 20 Surface protective layer

31 Exposure means (semiconductor laser)
32 Charging means (charger)
33 Developing means (developer)
33a Developing roller 33b Casing 34 Transfer means (transfer charger)
35 Fixing means (fixing device)
35a Heating roller 35b Pressurized roller 36 Cleaning means (cleaner)
36a Cleaning blade 36b Recovery casing 37 Separation means 38 Housing 41, 42 Arrows 44 Rotating axis 51 Recording medium (recording paper or transfer paper)
100 Image forming device (laser printer)

Claims (10)

A single-layer photosensitive layer containing a charge-generating substance and a charge-transporting substance, or a charge-generating layer containing a charge-generating substance and a charge-transporting layer containing a charge-transporting substance are laminated in this order on a conductive support. An electrophotographic photosensitive member having at least a laminated laminated photosensitive layer.
An electrophotographic photosensitive member, wherein the outermost surface layer of the electrophotographic photosensitive member contains metal oxide-polymer composite particles. The electrophotographic photosensitive member according to claim 1, wherein the metal oxide-polymer composite particles are in a form in which the metal oxide is exposed on the surface thereof. The electrophotographic photosensitive member according to claim 1 or 2, wherein the metal oxide particles have a number average primary particle diameter of 10 to 30 nm. The electrophotographic photosensitive member according to any one of claims 1 to 3, wherein the metal oxide-polymer composite particle has a number average primary particle diameter of 130 to 300 nm. The claim that the single-layer type photosensitive layer and the charge transport layer contain a binder resin, and the metal oxide-polymer composite particles are contained in a ratio of 10 to 25 parts by mass with respect to 100 parts by mass of the binder resin. The electrophotographic photosensitive member according to any one of 1 to 4. The electrophotographic photosensitive member according to any one of claims 1 to 5, wherein the outermost surface layer has a surface roughness Rz of 0.7 to 1.5 μm. The electrophotographic photosensitive member according to any one of claims 1 to 6, wherein the metal oxide is silica. The electrophotographic photosensitive member according to any one of claims 1 to 7, wherein the electrophotographic photosensitive member is a laminated electrophotographic photosensitive member having the laminated photosensitive layer. The electrophotographic photosensitive member according to any one of claims 1 to 8, wherein an undercoat layer is provided between the conductive support and the single-layer type photosensitive layer or the laminated type photosensitive layer. The electrophotographic photosensitive member according to any one of claims 1 to 9, the charging means for charging the electrophotographic photosensitive member, and the charged electrophotographic photosensitive member are exposed to form an electrostatic latent image. An exposure means, a developing means for developing the electrostatic latent image formed by exposure to form a toner image, a transfer means for transferring the toner image formed by development onto a recording medium, and the transferred said. A fixing means for fixing a toner image on the recording medium to form an image, a cleaning means for removing and recovering toner remaining on the electrophotographic photosensitive member, and static elimination of surface charge remaining on the electrophotographic photosensitive member. An image forming apparatus characterized in that it is provided with at least static elimination means.

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