JP2002196522A - Electrophotographic photoreceptor, image forming device and process cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor having high resolution and not causing image defects such as black spots, an image forming device using the photoreceptor and a process cartridge. SOLUTION: In the electrophotographic photoreceptor having a middle layer and a photosensitive layer on an electrically conductive substrate, the middle layer contains at least titanium oxide particles and a binder resin and the thickness of the photosensitive layer is 7-20 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photosensitive member (hereinafter, also simply referred to as "photosensitive member") used in the field of copying machines and printers, and an image forming apparatus and a process cartridge using the electrophotographic photosensitive member. Things.

[0002]

2. Description of the Related Art The photoreceptor for electrophotography has shifted from inorganic photoreceptors such as Se, arsenic, arsenic / Se alloy, CdS and ZnO to organic photoreceptors having excellent advantages such as pollution and ease of production. Organic photoreceptors using various materials have been developed.
In recent years, function-separated type photoreceptors in which charge generation and charge transport functions are assigned to different materials have become mainstream, and most of them have an intermediate layer provided on a conductive support, and a charge generation layer, Laminated photoconductors having a charge transport layer laminated thereon are widely used.

Turning to the electrophotographic process, the latent image forming method is roughly classified into analog image forming using a halogen lamp as a light source and digital image forming using an LED or a laser as a light source. Recently, digital latent image forming systems are rapidly becoming mainstream as hard copy printers for personal computers, and even in ordinary copiers, because of the ease of image processing and ease of application to multifunction devices. Therefore, higher quality output images have been required.

In digital image formation, a laser, particularly a semiconductor laser or an LED, is used as a light source when writing image information converted into a digital electric signal as an electrostatic latent image on a photosensitive member.

[0005] Such a semiconductor laser or LED
In the method using an array as a recording light source, an image is represented by a set and arrangement of minute dots called pixels, and 1200 dpi (dpi: 2. A recording density of more than (number of dots per 54 cm) has become possible.

Further, in order to design a high image quality, not only the optical system but also development process technologies such as reduction of toner particle size, minimization of toner scattering at the time of development or transfer, and cleaning technology of small particle size toner. Is important. However, 1200
When recording high-quality digital images of dpi or more,
It has been found that it is difficult to faithfully reproduce the electrostatic latent image formed on the photoreceptor simply by reducing the particle size of the toner, and the photoreceptor used also has a reduced recording density. Therefore, a design that can faithfully visualize a high-resolution image without causing a problem has been required.

However, studies on the resolution of the photoreceptor itself are sparse, and the resolution of the photoreceptor itself has not been considered a problem in the past. This is because, at a recording density of 400 dpi to 600 dpi, a photoconductor having a film thickness practically used has a sufficient resolution, and resolution degradation due to carrier diffusion depending on the film thickness has not been a problem. is there.

At the current recording density of 600 dpi or less, the thickness of a photoreceptor practically used is 20 to 35 μm. The film thickness is set based on factors such as sensitivity and printing durability (life) required for the photoconductor, and the latent image formed on the photoconductor does not cause a problem in reproducibility of recording density. However, in the case of a high-density latent image of 1500 dpi or more, in the case of a photosensitive member having a film thickness of 20 μm or more, carrier diffusion depending on the carrier traveling distance of the photosensitive member occurs to cause deterioration in resolution. A problem that makes it difficult to reproduce an accurate image has been clarified by the inventors' studies.

In order to prevent the resolution from deteriorating when a latent image is formed on a photosensitive member requiring high resolution, it is necessary to increase the surface charge density and reduce the thickness of the photosensitive layer. However, when the film thickness is small, the electric field intensity applied to the photosensitive layer is increased, and the occurrence of black spot image defects due to reversal development is likely to occur. Particularly, in the case of a photoreceptor that performs charging by a contact charging method, which has attracted attention in recent years, there is a problem in that deterioration of the photoreceptor (dielectric breakdown due to a pinhole defect) is more likely to occur.

[0010]

SUMMARY OF THE INVENTION In view of the above-mentioned problems of the prior art, the present invention provides an electrophotographic photosensitive member having high resolution and free from image defects such as black spots, and an image using the electrophotographic photosensitive member. An object of the present invention is to provide a forming apparatus and a process cartridge.

[0011]

The object of the present invention is achieved by the following constitution.

1. In an electrophotographic photoreceptor having an intermediate layer and a photosensitive layer on a conductive support, the intermediate layer contains at least titanium oxide particles and a binder resin, and the thickness of the photosensitive layer is 7 to 20 μm. An electrophotographic photosensitive member characterized by the following.

2. 2. The electrophotographic photoconductor according to the above item 1, wherein the photosensitive layer has a thickness of 10 to 15 μm.

3. 3. The electrophotographic photoreceptor according to the above 1 or 2, wherein the photosensitive layer comprises a charge generation layer and a charge transport layer.

4. The electrophotographic photoreceptor according to any one of the above items 1 to 3, wherein the titanium oxide particles have been subjected to a surface treatment.

5. 5. The method according to 4, wherein the surface treatment is a plurality of surface treatments, the first surface treatment is a surface treatment with an inorganic compound, and the last surface treatment is a surface treatment with a reactive organosilicon compound. Electrophotographic photoreceptor.

6. 6. The electrophotographic photoreceptor according to the above item 5, wherein the inorganic compound is at least one of silica and alumina, and the reactive organic silicon compound is methyl hydrogen polysiloxane.

[7] 6. The electrophotographic photoreceptor according to the above item 5, wherein the inorganic compound is at least one of silica and alumina, and the reactive organic silicon compound is an organic silicon compound represented by the general formula (1).

8. Wherein the mass ratio of the titanium oxide particles to the binder resin is 100 to 500 parts of the titanium oxide particles with respect to 100 parts of the binder resin.
8. The electrophotographic photoreceptor according to any one of 7.

9. Any one of the above 1 to 8, wherein the binder resin of the intermediate layer is a polyamide resin.
13. The electrophotographic photoreceptor according to item 6.

10. The average particle size of the titanium oxide particles is 1
The electrophotographic photoreceptor according to any one of the above items 1 to 9, wherein the electrophotographic photoreceptor has a thickness of 0 nm or more and 200 nm or less.

11. In an image forming apparatus having an electrophotographic photoreceptor and at least a charging unit, an image exposing unit, a developing unit, a transfer unit, and a cleaning unit, and performing image formation repeatedly, the electrophotographic photoreceptor may be any one of the above 1 to 10 An image forming apparatus comprising the electrophotographic photoreceptor described in the above item.

12. 12. The image forming apparatus according to the above item 11, wherein the charging unit is a contact charging system in which a charging member is brought into contact with an electrophotographic photoreceptor to perform charging.

13. 13. The process cartridge used in the image forming apparatus according to 11 or 12, wherein the electrophotographic photosensitive member according to any one of 1 to 10 and a charging unit, an image exposing unit, a developing unit, a transfer unit, and a cleaning unit. A process cartridge having at least one unit integrally and configured to be able to be taken in and out of the image forming apparatus.

Hereinafter, the present invention will be described in detail. The electrophotographic photoreceptor of the present invention is an electrophotographic photoreceptor having an intermediate layer and a photosensitive layer on a conductive support, wherein the intermediate layer contains at least titanium oxide particles and a binder resin, and the thickness of the photosensitive layer is Is 7 to 20 μm.

The titanium oxide particles of the present invention preferably have been subjected to a surface treatment. Here, the surface treatment means that the surface of the titanium oxide particles is coated with an inorganic compound such as silica, a metal or a metal oxide, a reactive organosilicon compound, an organometallic compound, or the like.

In order to suppress image defects such as black spots and obtain a good high-resolution image using the photoreceptor having a relatively thin photosensitive layer of 20 μm or less according to the present invention, a plurality of types of titanium oxide particles are required. Those that have been subjected to a surface treatment are preferred, and specifically, are first subjected to a surface treatment with an inorganic compound,
Further, those which have been finally subjected to a surface treatment with a reactive organosilicon compound are more preferable.

Specific examples of these surface treatment compounds include:
Examples of the inorganic compound include alumina, silica, zirconia, iron oxide, and zinc oxide. Among them, the treatment with alumina and silica is particularly preferred, and the treatment with alumina and then the treatment with silica are more preferable.
An inorganic treatment performed in stages is optimal.

In the surface treatment of the reactive organosilicon compound, it is preferable to use the compound represented by the general formula (1).

In the organosilicon compound represented by the general formula (1), the organic group in which carbon represented by R is directly bonded to silicon is methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl, dodecyl Alkyl groups such as phenyl, tolyl, naphthyl, biphenyl and the like, γ-glycidoxypropyl, β- (3,4
An epoxy-containing group such as -epoxycyclohexyl) ethyl,
(meth) acryloyl groups including γ-acryloxypropyl and γ-methacryloxypropyl, hydrous groups such as γ-hydroxypropyl and 2,3-dihydroxypropyloxypropyl, vinyl groups including vinyl and propenyl, and γ-
A mercapto-containing group such as mercaptopropyl, an amino-containing group such as γ-aminopropyl, N-β (aminoethyl) -γ-aminopropyl, γ-chloropropyl, 1,1,1-trifluoropropyl, nonafluorohexyl, Halogen-containing groups such as perfluorooctylethyl, other nitro,
And cyano-substituted alkyl groups. Examples of the hydrolyzable group for X include an alkoxy group such as methoxy and ethoxy, a halogen group, and an acyloxy group.

The organosilicon compound represented by the general formula (1) may be used alone or in combination of two or more. When n is 2 or more in a specific compound of the organosilicon compound represented by the general formula (1), a plurality of Rs may be the same or different. Similarly, when n is 2 or less, a plurality of Xs may be the same or different. When two or more organosilicon compounds represented by the general formula (1) are used, R and X may be the same or different between the respective compounds.

Examples of the compound where n = 0 include the following compounds. Tetrachlorosilane, diethoxydichlorosilane, tetramethoxysilane, phenoxytrichlorosilane, tetraacetoxysilane, tetraethoxysilane, tetraallyloxysilane, tetrapropoxysilane, tetraisopropoxysilane, tetrakis (2-methoxyethoxy) silane, tetrabutoxysilane , Tetraphenoxysilane, tetrakis (2-ethylbutoxy) silane, tetrakis (2-ethylhexyloxy) silane and the like.

Examples of the compound where n = 1 include the following compounds. That is, methyltrichlorosilane, vinyltrichlorosilane, ethyltrichlorosilane, allyltrichlorosilane, propyltrichlorosilane, butyltrichlorosilane, chloromethyltriethoxysilane, methyltrimethoxysilane, mercaptomethyltrimethoxysilane, trimethoxyvinylsilane, ethyltrimethoxy Silane, 3,3,4,4,5,5,6,6,6-nonafluorohexyltrichlorosilane, phenyltrichlorosilane, 3,3,3-trifluoropropyltrimethoxysilane, 3-chloropropyltrimethoxysilane ,
Butyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 2-aminoethylaminomethyltrimethoxysilane, benzyltrichlorosilane, methyltriacetoxysilane, chloromethyltriethoxysilane, ethyltriacetoxysilane , Phenyltrimethoxysilane, 3-
Allylthiopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-bromopropyltriethoxysilane, 3-allylaminopropyltrimethoxysilane, propyltriethoxysilane, hexyltrimethoxysilane, 3-aminopropyltriethoxy Examples thereof include silane, 3-methacryloxypropyltrimethoxysilane, bis (ethylmethylketoxime) methoxymethylsilane, pentyltriethoxysilane, octyltriethoxysilane, and dodecyltriethoxysilane.

Examples of the compound where n = 2 include the following compounds. Dimethyldichlorosilane, dimethoxymethylsilane, dimethoxydimethylsilane, methyl-3,
3,3-trifluoropropyldichlorosilane, diethoxysilane, diethoxymethylsilane, dimethoxymethyl-3,3,3-trifluoropropylsilane, 3-chloropropyldimethoxymethylsilane, chloromethyldiethoxysilane, diethoxydimethyl Silane, dimethoxy-3-mercaptopropylmethylsilane, 3,3
4,4,5,5,6,6,6-nonafluorohexylmethyldichlorosilane, methylphenyldichlorosilane,
Diacetoxymethylvinylsilane, diethoxymethylvinylsilane, 3-methacryloxypropylmethyldichlorosilane, 3-aminopropyldiethoxymethylsilane, 3- (2-aminoethylaminopropyl) dimethoxymethylsilane, t-butylphenyldichlorosilane,
3-methacryloxypropyldimethoxymethylsilane,
3- (3-cyanopropylthiopropyl) dimethoxymethylsilane, 3- (2-acetoxyethylthiopropyl) dimethoxymethylsilane, dimethoxymethyl-2-
Piperidinoethylsilane, dibutoxydimethylsilane,
3-dimethylaminopropyldiethoxymethylsilane,
Diethoxymethylphenylsilane, diethoxy-3-glycidoxypropylmethylsilane, 3- (3-acetoxypropylthio) propyldimethoxymethylsilane, dimethoxymethyl-3-piperidinopropylsilane, diethoxymethyloctadecylsilane, and the like. Can be

Examples of the compound where n = 3 include the following compounds. Trimethylchlorosilane, methoxytrimethylsilane, ethoxytrimethylsilane, methoxydimethyl-3,3,3-trifluoropropylsilane, 3-
Chloropropylmethoxydimethylsilane, methoxy-3
-Mercaptopropylmethylmethylsilane.

In particular, n = 1, and R is 4 to 8 carbon atoms.
And X is an alkoxy group such as methoxy, ethoxy and the like, and a compound of the following general formula (2) is preferred.

Formula (2) R—Si— (X) ₃ (R represents an alkyl group having 4 to 8 carbon atoms and X represents an alkoxy group) Examples of preferred compounds of the above formula (2) include The following compounds, trimethoxy-n-butylsilane, triethoxy-n-butylsilane, trimethoxy-i-butylsilane, trimethoxy-s-butylsilane, trimethoxyhexylsilane, trimethoxyoctylsilane trimethoxy-2-ethylhexylsilane are exemplified.

Other than the above, methyl hydrogen polysiloxane is particularly preferable. The surface treatment of the titanium oxide with the inorganic compound can be performed by a wet method. For example, the surface treatment of silica or alumina can be prepared as follows.

Titanium oxide particles (number average primary particle diameter: 50
nm) at a concentration of 50 to 350 g / L in water to form an aqueous slurry, to which a water-soluble silicate or a water-soluble aluminum compound is added. Thereafter, an alkali or an acid is added to neutralize the resultant, and silica or alumina is precipitated on the surface of the titanium oxide particles. Subsequently, filtration, washing and drying are performed to obtain a target surface-treated titanium oxide. When sodium silicate is used as the water-soluble silicate, it can be neutralized with an acid such as sulfuric acid, nitric acid and hydrochloric acid. On the other hand, when aluminum sulfate is used as the water-soluble aluminum compound, it can be neutralized with an alkali such as sodium hydroxide or potassium hydroxide.

The subsequent surface treatment with the reactive organosilicon compound can be performed by the following wet method.
That is, the reactive organosilicon compound is dissolved or suspended in an organic solvent or water, titanium oxide treated with the inorganic compound is added, and such a solution is mixed by stirring for several minutes to about 1 hour. In some cases, after a heat treatment, drying is performed through a step such as filtration to coat the titanium oxide surface with a silicon compound group. The reactive organic silicon compound may be added to a suspension in which titanium oxide is dispersed in an organic solvent or water.

The surface treatment with methylhydrogenpolysiloxane can be performed by the same wet method as that for the reactive organosilicon compound.

With respect to the amount of surface treatment, the amount of the surface treatment compound is preferably 0.1 to 50 parts by mass, more preferably 1 to 10 parts by mass, per 100 parts by mass of the untreated titanium oxide in the amount charged at the time of the surface treatment. . If the surface treatment amount is less than the above range, the surface treatment effect is not sufficiently imparted, resulting in adverse effects such as poor dispersibility and poor chargeability of the photoreceptor. If the amount is larger than the above range, the electrostatic characteristics of the photoconductor are similarly deteriorated, causing an increase in the residual potential and a decrease in the charged potential.

Next, the average particle size of the titanium oxide particles used in the present invention is preferably in the range of 10 nm to 200 nm. The coating solution for the intermediate layer using titanium oxide particles having the number average primary particle size in the above range has good dispersion stability, and the intermediate layer formed from such a coating solution has sufficient potential stability and black spots. Has a prevention function.

The particle size of the titanium oxide particles was magnified 10,000 times by transmission electron microscopy,
It is a measured value as an average diameter in the Feret direction by observing 00 particles as primary particles and performing image analysis.

The shape of the titanium oxide particles used in the present invention includes dendrites, needles, granules, and the like. The titanium oxide having such a shape has an anatase type, a rutile type, and an amorphous type. And the like, but particularly preferred is rutile-type titanium oxide.

Next, examples of the binder resin for the intermediate layer of the present invention include polyamide resins, vinyl chloride resins, vinyl acetate resins, and copolymer resins containing two or more of the repeating units of these resins. Among these binder resins, polyamide resins are preferable, and alcohol-soluble polyamides such as copolymerization and methoxymethylol are particularly preferable.

The amount of the surface-treated titanium oxide of the present invention dispersed in the binder resin is 50 to 1,000 parts by mass, preferably 100 to 100 parts by mass of the binder resin.
５００500 parts by mass. By using the surface-treated titanium oxide in this range, the dispersibility of the titanium oxide can be kept good, and a good intermediate layer free of black spots can be formed.

The thickness of the intermediate layer of the present invention is 0.5 to 15 μm.
And more preferably 1 to 7 μm. By using the film thickness in the above-mentioned range, an intermediate layer having good electrophotographic characteristics without black spots can be formed.

Next, the photosensitive layer of the electrophotographic photosensitive member of the present invention will be described. The photosensitive layer of the photoreceptor of the present invention may have a single-layer structure in which a charge generation function and a charge transport function are provided on the intermediate layer in one layer. It is preferable to adopt a configuration in which a generation layer and a charge transport layer are separated. By adopting a configuration in which functions are separated, an increase in residual potential due to repeated use can be controlled to be small, and other electrophotographic characteristics can be easily controlled according to the purpose. It is preferable that the photoreceptor for negative charging has a configuration in which a charge generation layer is provided on the intermediate layer and a charge transport layer is provided thereon. In the case of a positively charged photoreceptor, the order of the layer configuration is opposite to that of the negatively charged photoreceptor. The most preferred photosensitive layer structure of the present invention is a negatively charged photosensitive member having the function-separated structure.

The structure of the photosensitive layer of the functionally-separated negatively charged photosensitive member will be described below. Charge generation layer Charge generation layer: The charge generation layer contains one or more charge generation substances. As other substances, a binder resin and other additives may be contained as necessary.

As the charge generating substance, a known charge generating substance can be used. For example, phthalocyanine pigments, azo pigments, perylene pigments, azurenium pigments, and the like can be used. Among them, a phthalocyanine pigment having a specific crystal structure, for example, a titanyl phthalocyanine having a maximum peak at a Bragg angle 2θ of 27.2 ° with respect to Cu-Kα ray, a perylene pigment, for example, having a 2θ of 12.
Bisbenzimidazole perylene having a maximum peak at 4 is preferred.

As the binder resin for the charge generation layer, known resins can be used, and preferred resins include formal resin, butyral resin, silicon resin, silicon-modified butyral resin, phenoxy resin and the like. The ratio between the binder resin and the charge generating substance is preferably from 20 to 600 parts by mass per 100 parts by mass of the binder resin. The thickness of the charge generation layer is preferably from 0.01 μm to 2 μm.

Charge transport layer Charge transport layer: The charge transport layer contains a charge transport material and a binder resin for dispersing the charge transport material and forming a film. As other substances, additives such as antioxidants may be contained as necessary.

As the charge transport material, known charge transport materials can be used. For example, triphenylamine derivatives, hydrazone compounds, styryl compounds, benzidine compounds, butadiene compounds and the like can be used. Among these, a triphenylamine styryl compound having a specific structure and represented by the following general formula (3) is preferable.

[0055]

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In the general formula (3), R _{1 to} R ₃ represent a hydrogen atom, a halogen atom or an alkyl or alkoxy group having 1 to 5 carbon atoms. l, m. n represents the integer of 0-3. Ar
Represents a hydrogen atom or an aryl group which may have a substituent represented by R _{1 to} R ₃ . Among the aryl groups, a phenyl group is particularly preferred.

Specific examples of the triphenylamine styryl compound represented by the general formula (3) include the following compounds.

[0058]

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[0059]

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[0060]

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[0061]

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Examples of the resin used for the charge transport layer include polystyrene, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, polyvinyl butyral resin, epoxy resin, polyurethane resin, phenol resin, polyester resin, alkyd resin, and polycarbonate. Resins, silicone resins, melamine resins, and copolymer resins containing two or more of the repeating units of these resins. In addition to these insulating resins, high-molecular organic semiconductors such as poly-N-vinyl carbazole may be mentioned, and polycarbonate resins are preferred. The ratio of the binder resin to the charge transporting material is preferably from 10 to 200 parts by mass per 100 parts by mass of the binder resin. The thickness of the charge transport layer is preferably 5 to 20 μm, and the total thickness of the photosensitive layer, which is the sum of the thickness of the charge generation layer and the charge generation layer, is 7 to 20 μm. More preferably, the thickness of the photosensitive layer is 10 to 1
5 μm is preferred. By making the thickness of the photosensitive layer thin as described above, diffusion of carriers generated in the photosensitive layer can be prevented. Further, by providing the intermediate layer below the thin layer photosensitive layer, a thin layer photosensitive layer can be formed. Black spots that easily occur in the layer can be effectively prevented.

Although the most preferred layer configuration of the photoreceptor of the present invention has been described above, other layer configurations of the photoreceptor may be used in the present invention.

The intermediate layer and the photosensitive layer of the present invention are formed by dissolving or dispersing the materials of the above-mentioned respective layers in an appropriate solvent or dispersion medium and coating. As the solvent or dispersion medium used, n-butylamine, diethylamine, ethylenediamine, isopropanolamine, triethanolamine, triethylenediamine, N, N-dimethylformamide, acetone, methylethylketone, methylisopropylketone, cyclohexanone, benzene, toluene,
Xylene, chloroform, dichloromethane, 1,2-dichloroethane, 1,2-dichloropropane, 1,1,2
-Trichloroethane, 1,1,1-trichloroethane,
Examples include trichloroethylene, tetrachloroethane, tetrahydrofuran, dioxolan, dioxane, methanol, ethanol, butanol, 1-propanol, isopropanol, ethyl acetate, butyl acetate, dimethyl sulfoxide, methyl cellosolve and the like.

As a coating method for producing the electrophotographic photoreceptor of the present invention, coating methods such as dip coating, spray coating and circular amount control type coating are used. Does not dissolve the underlying film as much as possible,
In order to achieve uniform coating, it is preferable to use a coating method such as spray coating or coating with a circular amount control type (a typical example is a circular slide hopper type). The spray coating is described in detail in, for example, JP-A-3-90250 and JP-A-3-269238, and the circular amount control type coating is described in, for example, JP-A-58-1890.
No. 61 discloses this in detail.

FIG. 1 is a sectional view of an image forming apparatus as an example of the present invention. In FIG. 1, reference numeral 50 denotes a photoconductor drum (photoconductor) serving as an image carrier, which is grounded and driven to rotate clockwise. 52 is a charger using a charging roller (charging means)
In this case, a contact charging method is used in which a uniform charge is applied to the peripheral surface of the photoconductor drum 50 and the charging roller is brought into contact with the peripheral surface of the photoconductor drum 50 to perform charging. Power supply (not shown) for charging roller
A bias voltage composed of DC and AC components is applied to the photosensitive drum 50 in a state where the amount of generated ozone is extremely small.
Is charged. The bias voltage is usually ± 50
0 to 1000V DC bias and 100
Hz to 10 KHz, 200 to 3500 V (pp) A
C bias.

The charging roller is driven or forcedly rotated while being pressed against the photosensitive drum 50. The pressure contact with the photoconductor drum 50 is preferably 10 to 100 g / cm, and the rotation of the charging roller is preferably 1 to 8 times the peripheral speed of the photoconductor drum 50.

The charging roller is composed of a cored bar and a rubber layer of chloroprene rubber, urethane rubber, silicone rubber, or the like, which is a conductive elastic member provided on the outer periphery thereof, or a sponge layer thereof, preferably an outermost layer. 0.01 ~ 1μ
The protective layer is formed of a m-thick release fluorine-based resin or silicone resin layer.

Prior to charging by the charger 52, exposure is performed by a pre-charging exposure unit 51 using a light emitting diode or the like to eliminate the history of the photoconductor in the previous image formation, and the peripheral surface of the photoconductor is discharged. Is also good.

After the photosensitive member is uniformly charged, image exposure based on the image signal is performed by an image exposure device 53 as an image exposure means. The image exposure device 53 in this figure uses a laser diode (not shown) as an exposure light source. Rotating polygon mirror 5
31, the light on the photosensitive drum is scanned by the light whose optical path is bent by the reflection mirror 532 through the fθ lens and the like,
An electrostatic latent image is formed.

Next, the electrostatic latent image is developed by a developing device 54 as a developing means. A developing device 54 containing a developer including a toner and a carrier is provided on the periphery of the photoreceptor drum 50, and development is performed by a developing sleeve 541 that contains a magnet and rotates while holding the developer.
The inside of the developing device 54 is composed of a developer stirring member, a developer conveying member, a conveying amount regulating member 542, and the like. The developer is stirred and conveyed and supplied to the developing sleeve. It is controlled by the regulating member 542. The transport amount of the developer varies depending on the linear speed of the organic electrophotographic photosensitive member to be applied and the specific gravity of the developer, but is generally 20 to 200.
mg / cm ² .

The developer is, for example, a carrier having the above-described ferrite as a core and an insulating resin coated around the core, a coloring agent such as carbon black using the above-mentioned styrene acrylic resin as a main material, a charge control agent, and the present invention. The toner is composed of colored particles made of a low molecular weight polyolefin and a toner in which silica, titanium oxide or the like is externally added.
The layer is regulated to a layer thickness of 0 to 600 μm and transported to a development area, where development is performed. At this time, development is usually performed by applying a DC bias voltage between the photosensitive drum 50 and the developing sleeve 541 and, if necessary, an AC bias voltage. The developer is developed in a state of contact or non-contact with the photoconductor.

After the image is formed, the recording paper P is fed to the transfer area by the rotation of the paper feed roller 57 when the timing of the transfer is adjusted.

In the transfer area, a transfer roller (transfer device) 58 as transfer means is pressed against the peripheral surface of the photosensitive drum 50 in synchronization with the transfer timing, and the fed recording paper P is sandwiched and transferred. Is done.

Next, the recording paper P is neutralized by a separation brush (separator) 59 which is brought into pressure contact with the transfer roller almost simultaneously, is separated by the peripheral surface of the photosensitive drum 50, is conveyed to the fixing device 60, and is heated by the heat roller. 601 and pressure roller 6
After the toner is fused by heating and pressurizing 02, the toner is discharged to the outside of the apparatus via a paper discharge roller 61. The transfer roller 58 and the separation brush 59 are retracted and separated from the peripheral surface of the photosensitive drum 50 after the recording paper P has passed to prepare for the formation of the next toner image.

On the other hand, the photosensitive drum 50 from which the recording paper P has been separated removes and cleans the residual toner by pressing the blade 621 of the cleaning device (cleaning means) 62.
Upon receiving the charge elimination by the pre-charge exposure unit 51 and the charging by the charger 52 again, the image forming process starts.

Reference numeral 70 denotes a detachable process cartridge in which a photosensitive member, a charger, a transfer device, a separator, and a cleaning device are integrated.

As the image forming apparatus, the above-mentioned photosensitive member,
The components such as the developing device and the cleaning device may be integrally combined as a process cartridge, and this unit may be configured to be detachable from the apparatus main body. Also, a process cartridge is formed by integrally supporting at least one of a charger, an image exposing unit, a developing unit, a transfer or separating unit, and a cleaning unit together with a photoreceptor. It may be configured to be detachable using a guide means such as a rail of the apparatus body.

The process cartridge generally includes an integral type cartridge and a separate type cartridge described below. The integral type cartridge is configured such that at least one of a charger, an image exposing unit, a developing unit, a transfer or separating unit, and a cleaning unit is integrally formed with a photoconductor, and is detachable from an apparatus main body. Are a charging device, an image exposure device, a developing device, a transfer or separation device, and a cleaning device which are configured separately from the photoreceptor, but have a configuration detachable from the apparatus main body and are incorporated in the apparatus main body. When integrated, it is integrated with the photoconductor. The process cartridge in the present invention includes both types of cartridges.

The organic electrophotographic photoreceptor of the present invention is applicable to general electrophotographic apparatuses such as electrophotographic copying machines, laser printers, LED printers, and liquid crystal shutter printers. It can be widely applied to devices such as printing, plate making, and facsimile.

[0081]

EXAMPLES Hereinafter, the present invention will be described in detail with reference to examples, but embodiments of the present invention are not limited thereto. In the description, “parts” means “parts by mass”.

Example 1 A photoreceptor 1 was produced as follows.

The following intermediate layer coating solution was dip-coated on a cylindrical aluminum conductive substrate having a diameter of 80 mm to form an intermediate layer having a dry film thickness of 4.0 μm.

<Intermediate Layer Coating Solution> Polyamide resin “CM8000” (manufactured by Toray Industries, Inc.) 10 parts Titanium oxide “SMT500SAS” (first time: silica / alumina treatment second time: methyl hydrogen polysiloxane treatment: rutile type: Teica) 30 parts methanol 100 parts The above was dispersed using an ultrasonic homogenizer to prepare an intermediate layer coating solution.

Next, the following charge generation layer coating solution was applied by a circular slide hopper to form a charge generation layer having a dry film thickness of 0.3 μm.

<Coating Solution for Charge Generating Layer> 12 parts of a charge generating material (Y-type titanyl phthalocyanine pigment having remarkable peaks at X-ray diffraction Bragg angles 2θ of 9.5 °, 24.1 ° and 27.2 °) 24 parts of polyvinyl butyral resin "S-LEC BL-1" (manufactured by Sekisui Chemical Co., Ltd.) 24 parts t-butyl acetate 300 parts The above were mixed and dispersed with a sand grinder to prepare a charge generating layer coating liquid.

The following charge transport layer coating solution was applied on the charge generation layer using a circular slide hopper,
C .; heat-cured for 60 minutes to form a charge transport layer having a dry film thickness of 14.5 μm.

<Coating solution for charge transport layer> Charge transport material (CT-6) 200 parts Polycarbonate "Iupilon Z300" (manufactured by Mitsubishi Gas Chemical Company) 300 parts 2,6-di-t-butyl-4-phenylphenol 5 parts 2,000 parts of 1,2-dichloroethane The above were mixed and dissolved to prepare a charge generating layer coating solution.

Examples 2 to 5 The same procedures as in Example 1 were carried out except that the titanium oxide shown in Table 1 was used instead of the titanium oxide used in Example 1, and the thickness of the charge transport layer and the thickness of the intermediate layer shown in Table 1 were used. In the same manner as in Example 1, Photoconductors 2 to 5 were produced.

Examples 6 to 10 The charge transport material (CT-) of the charge transport layer used in Example 1 was used.
Example 6 was the same as Example 1 except that 6) was replaced with (CT-14) and titanium oxide shown in Table 1 was used instead of titanium oxide, and the thickness of the charge transport layer and the thickness of the intermediate layer shown in Table 1 were used. Photoconductors 6 to 10 were produced in the same manner.

Comparative Example 1 A photoreceptor 11 was produced in the same manner as in Example 1 except that the thickness of the charge transport layer was changed to 24.5 μm.

Comparative Example 2 Photoconductor 12 was prepared in the same manner as in Example 1 except that titanium oxide was removed from the intermediate layer of Example 1 and the dry film thickness was changed to 1.0 μm.
Was prepared.

Comparative Example 3 A photoconductor 13 was prepared in the same manner as in Example 1, except that the thickness of the charge transport layer in Example 6 was changed to 20.5 μm.

Comparative Example 4 Photoconductor 14 was prepared in the same manner as in Example 6 except that titanium oxide was removed from the intermediate layer of Example 6 and the dry film thickness was changed to 1.0 μm.
Was prepared.

[0095]

[Table 1]

* Measurement Method of Film Thickness The film thickness of the photosensitive layer in the above table was calculated from the amount of the solid content of the coating solution. Also, an eddy current type film thickness measuring device EDDY560C
Using HELMUT FISCHER GMBTECO, the thickness of the entire layer including the intermediate layer and the thickness of the intermediate layer from which the photosensitive layer has been peeled are measured, and the thickness of the photosensitive layer can be measured from the difference. In this measuring method, the uniform film thickness portion is measured at random at 10 points, and the average value is defined as the film thickness of the photosensitive layer.

(Evaluation) Each of the photoconductors was subjected to Konica 7050
Remodeling machine (roller contact charging system, laser exposure 1200d
Using a pi recording, a polymerized toner having an average particle diameter of 6.5 μm), a continuous repetition cycle of charging, exposure, and static elimination was performed 6000 times at normal temperature and normal humidity (20 ° C., 50% RH). , The unexposed portion potential VH and the exposed portion potential VL were measured. High temperature and high humidity (30 ° C, 83% RH), low temperature and low humidity (7 ° C,
(21% RH), continuous image copying of 10,000 sheets of A4 paper was performed to confirm the presence of black spots and other image defects. Evaluation of the resolution is normal temperature and normal humidity (20 ° C, 50%
(RH), the resolution chart of the line image was copied and evaluated. Table 2 shows the results.

[0098]

[Table 2]

[0099]

As shown in Table 2, the electrophotographic photoreceptor of the present invention has a high resolution characteristic and remarkably improves the occurrence of black spots in the contact charging process without deteriorating the electrostatic characteristics. On the other hand, in the electrophotographic photoreceptor having an intermediate layer and the electrophotographic photoreceptor having a photosensitive layer having a thickness of more than 20 μm, a decrease in resolution or occurrence of black spot image defects is observed.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an image forming apparatus as one example of the present invention.

[Explanation of symbols]

 Reference Signs List 50 photoreceptor drum (or photoreceptor) 51 pre-charging exposure unit 52 charger 53 image exposure unit 54 developing unit 541 developing sleeve 542 transport amount regulating member 57 paper feed roller 58 transfer roller (transfer unit) 59 separation brush (separator) Reference Signs List 60 fixing device 61 paper discharge roller 62 cleaning device 70 process cartridge

Claims (13)

[Claims] 1. An electrophotographic photoreceptor having an intermediate layer and a photosensitive layer on a conductive support, wherein the intermediate layer contains at least titanium oxide particles and a binder resin, and the photosensitive layer has a thickness of 7 to An electrophotographic photosensitive member having a thickness of 20 μm. 2. The electrophotographic photosensitive member according to claim 1, wherein the thickness of the photosensitive layer is 10 to 15 μm. 3. The electrophotographic photosensitive member according to claim 1, wherein the photosensitive layer comprises a charge generation layer and a charge transport layer. 4. The electrophotographic photoreceptor according to claim 1, wherein the titanium oxide particles have been subjected to a surface treatment. 5. The surface treatment is a plurality of surface treatments,
The first surface treatment is a surface treatment with an inorganic compound,
The electrophotographic photoreceptor according to claim 4, wherein the last surface treatment is a surface treatment with a reactive organosilicon compound. 6. The electrophotographic photoreceptor according to claim 5, wherein the inorganic compound is at least one of silica and alumina, and the reactive organic silicon compound is methyl hydrogen polysiloxane. 7. The method according to claim 5, wherein the inorganic compound is at least one of silica and alumina, and the reactive organic silicon compound is an organic silicon compound represented by the following general formula (1). Electrophotographic photoreceptor. Formula (1) (R) _n -Si- (X) _4-n (wherein, Si is a silicon atom, R is an organic group in which carbon is directly bonded to the silicon atom, and X is hydrolyzable. Represents a group, and n represents an integer of 0 to 3.) 8. The mass ratio of the titanium oxide particles to the binder resin is 100 to 500 parts of the titanium oxide particles to 100 parts of the binder resin.
8. The electrophotographic photoreceptor according to any one of 7. 9. The method according to claim 1, wherein the binder resin of the intermediate layer is a polyamide resin.
13. The electrophotographic photoreceptor according to item 6. 10. The titanium oxide particles having an average particle size of 10
The electrophotographic photoreceptor according to any one of claims 1 to 9, wherein the electrophotographic photoreceptor has a thickness of not less than 200 nm and not more than 200 nm. 11. An image forming apparatus having an electrophotographic photoreceptor and at least a charging unit, an image exposing unit, a developing unit, a transfer unit, and a cleaning unit, wherein the electrophotographic photoreceptor is repeatedly formed. An image forming apparatus comprising the electrophotographic photosensitive member according to any one of claims 10 to 10. 12. An image forming apparatus according to claim 11, wherein said charging means is of a contact charging type in which a charging member is brought into contact with an electrophotographic photosensitive member to perform charging. 13. A process cartridge used in the image forming apparatus according to claim 11 or 12, wherein the electrophotographic photosensitive member according to claim 1 and a charging unit, an image exposure unit, and a development unit. A process unit having at least one of a transfer unit and a cleaning unit, and configured to be able to be taken in and out of the image forming apparatus.