JP2003195547A - Electrophotographic photoreceptor, image forming method, image forming apparatus and process cartridge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-durability electrophotographic photoreceptor capable of realizing the improvement of image quality and the reduction of environmental dependency, and made excellent in stability to toner removing performance and the squeaking of a cleaning blade, and further capable of yielding a distinct image even in a high humidity environment, and to provide an image forming method, an image forming apparatus and a process cartridge using the electrophotographic photoreceptor. <P>SOLUTION: This electrophotographic photoreceptor is characterized in having a layer incorporating organic particulates whose cohesion rate: N (%) is in the following range on a conductive supporting body. 0≤N≤10. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photoreceptor, an image forming method, an image forming apparatus and a process cartridge used in the field of copying machines and printers.

[0002]

2. Description of the Related Art In recent years, an organic photoconductor containing an organic photoconductive substance has been most widely used as an electrophotographic photoconductor. Organic photoconductors are advantageous over other photoconductors because it is easy to develop materials for various exposure light sources from visible light to infrared light, materials that do not cause environmental pollution can be selected, and manufacturing costs are low. However, on the other hand, the mechanical strength is weak, and the deterioration or scratch of the surface layer of the photoconductor is apt to occur when copying or printing a large number of sheets.

In order to satisfy various required characteristics as described above, various things have been studied so far.

As a problem for improving the durability of the above-mentioned organic photoconductor, it has been strongly demanded to suppress abrasion due to rubbing of a cleaning blade or the like. As an approach for this, a technique has been studied in which fine particles are contained on the surface of the photoconductor to reduce the frictional force with the blade. For example, JP-A-5-181291 reports that a photosensitive layer contains fine particles of alkylsilsesquioxane resin. However, the alkyl silsesquioxane resin fine particles have hygroscopicity, and in a high humidity environment, the wettability of the surface of the photoconductor becomes large, the resolution decreases and the frictional force with the blade increases, and blade squeal occurs. There is such a problem. On the other hand, JP-A-63-5
Japanese Patent No. 6658 reports a photosensitive layer containing a fluororesin powder in the photosensitive layer. However, the fluororesin powder has a problem that sufficient surface strength cannot be obtained and streak failure due to scratches on the surface of the photoconductor is likely to occur.

As a result of studying this problem, introduction of a fluorine atom-containing group to the surface of the particle is effective for improving the wettability of the particle, and wetting of the fine particle itself is effective for suppressing blade squeaking. In addition to improving the properties, it was found that it is important to disperse the particles uniformly in the photosensitive layer. When a fluorine atom-containing group is introduced, the wettability of the particle surface is reduced, and in particular, it is a cause of image blurring.
_Although it tends to suppress the adsorption of electrophiles such as ₂ and the problem of fog and image blurring, the conventional technology of particles containing fluorine atoms simultaneously satisfies the particle wettability and uniform dispersibility. The result was not obtained, and the problems of the surface strength of the photoreceptor and the image blur could not be sufficiently satisfied, and the image characteristics such as image blur and the durability were not satisfied at the same time. Further, it has been found that image defects such as image blur are not improved unless the uniform dispersibility of the fluorine atom-containing particles is achieved.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and is a highly durable electrophotographic photosensitive member (hereinafter, referred to as "photosensitive member", which can improve image quality and reduce environmental dependence).
(Also simply referred to as a photoconductor), and also to provide an electrophotographic photoconductor having excellent toner cleaning performance and stability against squeal of a cleaning blade, and a clear image can be obtained even in a high humidity environment. An object is to provide an electrophotographic photosensitive member, an image forming method using the electrophotographic photosensitive member, an image forming apparatus, and a process cartridge.

[0007]

The object of the present invention can be achieved by the following constitutions.

1. An electrophotographic photoreceptor having a layer containing organic fine particles having an agglomeration rate: N (%) in the following range on a conductive support.

0 ≦ N ≦ 10 2. In an electrophotographic photoreceptor having an intermediate layer, a charge generation layer, a charge transport layer and a surface layer on a conductive support, the surface layer may contain organic fine particles having an agglomeration ratio N (%) in the following range. Characteristic electrophotographic photoreceptor.

0 ≦ N ≦ 10 3. The number average particle diameter of the organic fine particles is 10 to 5,000 n.
3. The electrophotographic photosensitive member described in 1 or 2 above, wherein m is m.

4. 4. The electrophotographic photosensitive member according to any one of 1 to 3 above, wherein the organic fine particles are synthesized by a dispersion polymerization method.

5. 5. The electrophotographic photosensitive member according to any one of 1 to 4 above, wherein a contact angle of pure water on the surface of the electrophotographic photosensitive member is 90 to 120 °.

6. An electrophotographic image is formed by using the electrophotographic photosensitive member according to any one of 1 to 5 above.

7. An image forming apparatus, wherein an electrophotographic image is formed by using the image forming method described in 6 above.

8. At least the electrophotographic photosensitive member according to any one of 1 to 5 above, a charging device, an image exposing device, a developing device,
A process cartridge comprising at least one of a transfer device and a cleaning device, which is configured to be able to be taken in and out of an image forming apparatus.

In the present invention, the organic fine particles are dispersed in the layer forming the surface layer of the electrophotographic photosensitive member as primary particles without causing agglomeration, so that the surface of the electrophotographic photosensitive member is modified and image blurring occurs. Thus, an electrophotographic photosensitive member having both the image characteristics such as the above and the mechanical strength is achieved.

That is, the present invention is characterized in that organic fine particles are dispersed and contained in a layer forming a surface layer of an electrophotographic photosensitive member in an aggregated state in which an aggregate ratio: N (%) is 0 to 10%, which is very small. To do. The electrophotographic photosensitive member having such a surface layer has high image quality that achieves both image characteristics such as image blur and mechanical strength,
It can have high durability characteristics. The aggregation rate is 10
If it is larger than 0.1%, image blurring is likely to occur, sharpness is likely to be deteriorated, and abrasion resistance is deteriorated due to desorption of agglomerated fine particles from the surface layer, and streaky scratches are likely to occur.

The aggregation rate will be described with reference to FIG. The aggregation rate of the present invention is the number of independent fine particles in which organic fine particles are completely separated and dispersed as primary particles as x (in FIG. 1,
(1 to 6), (10 to 15) and (20) are independent fine particles and x is 13), and the number of aggregated particles in which two or more fine particles are aggregated is y ((7 to 9) in FIG. 1, (16, 17), (1
When 8 and 19) are aggregated fine particles and y is 3), the aggregation rate is represented by the following formula.

N (%) = 100y / (x + y) = 100
× 3 / (13 + 3) = 18.8 The aggregation rate N of the present invention is 0 to 10%, preferably 0 to 7%, more preferably 0 to 4%.

Agglomeration rate of the organic fine particles contained in the surface layer of the present invention: N is 0 to 10%. The organic fine particles dispersed at such an agglomeration rate are the same as those of conventionally known electrophotographic photoreceptors containing organic fine particles. Are clearly distinguished.

That is, the fluorine fine particle-dispersed photoconductors described in JP-A-8-328287, JP-A-9-62017 and the like are prepared by dispersing a mixed solution of a fluorinated ethylene resin, a polycarbonate resin and a solvent with a sand grinder and fluorinating the mixture. A dispersion liquid of ethylene resin particles is prepared, and the aggregation ratio N of the fluorinated ethylene particles of the layer (charge transport layer) prepared using the dispersion liquid is a value larger than 10%, and the layer is a surface layer. In such a photoreceptor, the reduction in the wettability of the surface layer and the abrasion resistance cannot be achieved at the same time.

In order to disperse and contain the organic fine particles having an agglomeration rate of 0 to 10% in the surface layer of the electrophotographic photosensitive member of the present invention, the conventional technique of dispersing solid fine particles in a binder resin is incomplete and new. Although a technique for preparing a dispersion liquid of solid fine particles is required, a technique for preparing a fine particle dispersion liquid using a dispersion polymerization method was used as the technique for preparing the dispersion liquid in the present invention. The technique for producing a fine particle dispersion liquid by the dispersion polymerization method will be described below.

The dispersion polymerization method of the present invention is a dispersion stabilizer, and in a organic solvent in which a polymerizable monomer is dissolved, a polymer is precipitated as the polymerization of the polymerizable monomer progresses, and a particle dispersion polymer is obtained. This refers to a polymerization method by which a polymer product is obtained. Specifically, it refers to "dispersion polymerization method" described in "Cutting-edge technology of ultrafine particle polymer" supervised by Soichi Muroi Publisher, CMC pages 34-45, etc. .

In the dispersion polymerization method, the polymerizable monomer is used as a component of the polymerization system for proceeding the polymerization,
A dispersion stabilizer, a polymerization initiator, a dispersion medium (solvent), etc. are required, and these components will be described below.

The dispersion stabilizer used in the dispersion polymerization is required to stably disperse the particulate polymer precipitated from the dispersion medium, and the amphiphilic polymer having an affinity for both the dispersion medium and the particulate polymer. Is preferred. In addition to this, in the present invention, it is preferable to use a polymer that does not deteriorate the electrophotographic characteristics (chargeability, sensitivity, etc.). As a dispersion stabilizer used in dispersion polymerization, polycarbonate, polyester,
Although various polymers such as polyamide are used, examples of the polymer preferably used include a polycarbonate-based resin having a repeating unit of a carbonate structure which exhibits a good effect on both amphipathicity and electrophotographic properties. .

For example, polymers and copolymers of repeating units having a carbonate structure represented by the following general formula (1) are preferable.

[0027]

[Chemical 1]

(In the formula, A is a single bond, a linear, branched or cyclic alkylidene group having 1 to 10 carbon atoms, an aryl-substituted alkylidene group, an arylenedialkylidene group, or -O-, -S-, -CO. -, - SO- and -SO ₂ -
And R ₁ , R ₂ , R ₃ and R ₄ represent hydrogen, halogen or an alkyl group or alkenyl group having 1 to 4 carbon atoms. ) The concentration of the dispersion stabilizer is 0.1 to 100 parts by mass of the dispersion medium.
200 parts by mass is preferred.

If it is less than 0.1 part by mass, the dispersion of the particulate polymer is not stable, and if it is more than 200 parts by mass, the dispersion stabilizers are likely to aggregate in the dispersion medium to form a uniform particulate polymer. Easy to disturb.

As the polymerizable monomer used in the dispersion polymerization of the present invention, a polymerizable monomer that promotes radical polymerization can be used. That is, a vinyl-based monomer is preferable as the radically polymerizable monomer used in the present invention. For example, acrylate, methacrylate, styrene,
Fluorine-substituted vinyl monomers such as acrylate, methacrylate, styrene and divinylbenzene are preferably used.

As the dispersion medium (solvent) used in the dispersion polymerization of the present invention, the dispersion stabilizer and the solvent capable of dissolving the polymerizable monomer are used. These solvents are generally organic solvents, but if necessary, mixed solvents of organic solvents,
Alternatively, a mixed solvent of water and an organic solvent can be used.

Examples of the organic solvent used in the dispersion polymerization of the present invention include methylochlore, ethylochlore, chloroform, monochlorobenzene, dichlorobenzene, tetrahydrofuran, dioxolane, dioxane, benzene, toluene, xylene, mesitylene, alcohols, esters and hexane. , Heptane, ligroin, kerosene, tetralin, ketones, ethers, dimethylformamide, acetonitrile and the like are preferably used.

The following compounds are used as the polymerization initiator used in the dispersion polymerization of the present invention. That is, AI
BN (Azobis- (2,4-dimethylva
leronitrile)), ADVN (Azobis
isobutyronitril), ACPA (Az
obis- (4-cyanopentanoic ac
id)), AMBN (Azobis- (2-methy
lbutyronitril)), BPO (Benz
Oyl peroxide) is preferably used.

In the dispersion polymerization of the present invention, a dispersion stabilizing auxiliary agent (an auxiliary agent for stably dispersing the particulate polymer) can be used. As the dispersion stabilizing aid, for example, a nonionic surfactant or the like is used.

Polymerization Operation of Dispersion Polymerization As will be specifically shown in the synthesis examples described later, dispersion polymerization is carried out in a dispersion medium (organic solvent) by a dispersion stabilizer (binder resin), a polymerizable monomer, a polymerization initiator and, if necessary, dispersion. Dissolve the stabilizing aid uniformly, and, if necessary, in the presence of other substances,
(Or, if necessary, it may be added in the middle) Polymerization is carried out by heating, etc., and with the polymerization of the polymerizable monomer, a particulate polymer is deposited by precipitation from a homogeneous system. The polymer of (1) grows to obtain a particulate polymer having a uniform particle size distribution. Each component used in dispersion polymerization (dispersion medium, dispersion stabilizer, polymerizable monomer, etc.)
Each may be a single one, but it is also possible to use two or more types in combination to control the particle size and generate a copolymer. Further, two kinds of polymerization initiators may be used in combination to form a particulate polymer having a wide particle size distribution or a particle size distribution having two peaks.

The amounts of the components used in the above-mentioned dispersion polymerization polymerization system are preferably used in the following mass ratios.

Preferred mass ratio dispersion stabilizer of material components: 0.1 to 200 parts by mass per 100 parts by mass of organic solvent Polymerizable monomer: 1 to 100 parts by mass of binder resin.
Parts by mass to 200 parts by mass Polymerization initiator: 0.01 parts by mass to 50 parts by mass with respect to 100 parts by mass of monomer Dispersion stabilizing aid: 0.001 with respect to 100 parts by mass of monomer
Parts by mass to 10 parts by mass By using the above mass ratio, the dispersion polymerization can be stably proceeded. Further, in the above, a method of adding the polymerizable monomer, the polymerization initiator and the like to the polymerization system stepwise or continuously can also be appropriately used.

The number average particle size of the organic fine particles of the present invention is 10
~ 5000 nm is preferred. Furthermore, 20-500 nm is preferable. When it is less than 10 nm, the effect of improving the cleaning property and the transfer rate of the toner is small. The number average particle diameter is a measurement value obtained by observing 100 organic particles as primary particles at random by enlarging organic fine particles 2000 times by observation with a transmission electron microscope and calculating the average particle diameter in the Feret direction by image analysis.

In the present invention, the organic fine particle solution obtained by the dispersion polymerization method may be used as it is as a coating liquid, and the coating liquid may be coated and dried to form the surface layer of the electrophotographic photoreceptor. The organic fine particle solution is prepared by adding additives such as a charge transporting substance, an antioxidant and a coating aid to prepare a surface layer coating solution, which is then coated and dried to form the surface layer of the electrophotographic photoreceptor. You may.

Next, the constitution of the electrophotographic photosensitive member using the polymer obtained by the dispersion polymerization method of the present invention will be described.

The polymer obtained by the dispersion polymerization method of the present invention is
It is preferably contained in the charge transport layer forming the surface layer of the organic photoreceptor, the protective layer, or the like. Hereinafter, the organic photoreceptor using the polymer of the present invention as the surface layer will be mainly described.

In the present invention, the organic photoconductor is an electrophotographic photoconductor having an organic compound having either one of the charge generation function and the charge transport function, which is essential for the construction of the electrophotographic photoconductor. This means that it includes all known organic electrophotographic photoreceptors such as a photoreceptor composed of a known organic charge generating material or an organic charge transporting material and a photoreceptor composed of a polymer complex having a charge generating function and a charge transporting function.

The layer structure of the organic photoreceptor is not particularly limited, but a charge generation layer, a charge transport layer, or a charge generation / charge transport layer (a layer having the functions of charge generation and charge transport in the same layer).
It is preferable to adopt a constitution in which a protective layer is coated on the photosensitive layer and the like, if necessary.

Conductive Support As the conductive support used in the photoconductor of the present invention, either a sheet or a cylinder may be used. In order to design the image forming apparatus compactly, the conductive support is cylindrical. A support is preferred.

The cylindrical conductive support means a cylindrical support required to form an image endlessly by rotating, and has a straightness of 0.1 mm or less and a shake of 0.1 mm.
A conductive support in the following range is preferable. When the circularity and the shake range are exceeded, good image formation becomes difficult.

As the conductive material, a metal drum such as aluminum or nickel, a plastic drum on which aluminum, tin oxide, indium oxide or the like is deposited, or a paper / plastic drum coated with a conductive substance can be used. It is preferable that the conductive support has a specific resistance of 10 ³ Ωcm or less at room temperature.

The conductive support used in the present invention may have a surface on which a pore-treated alumite film is formed. The alumite treatment is usually carried out in an acidic bath of chromic acid, sulfuric acid, oxalic acid, phosphoric acid, boric acid, sulfamic acid, etc., but anodizing treatment in sulfuric acid gives the most preferable result. In the case of anodizing treatment in sulfuric acid, it is preferable that the sulfuric acid concentration is 100 to 200 g / L, the aluminum ion concentration is 1 to 10 g / L, the liquid temperature is about 20 ° C., and the applied voltage is about 20 V. It is not limited. The average thickness of the anodized film is usually 2
It is preferably 0 μm or less, and particularly preferably 10 μm or less.

Intermediate Layer In the present invention, an intermediate layer having a barrier function may be provided between the conductive support and the photosensitive layer.

In the present invention, an intermediate layer (lower layer) is provided between the support and the photosensitive layer in order to improve adhesion between the conductive support and the photosensitive layer or prevent charge injection from the support. (Including a pulling layer) can also be provided. Examples of the material of the intermediate layer include a polyamide resin, a vinyl chloride resin, a vinyl acetate resin, and a copolymer resin containing two or more of repeating units of these resins. Among these undercoat resins, a polyamide resin is preferable as a resin that can reduce the increase in residual potential due to repeated use. The thickness of the intermediate layer using these resins is 0.01 to 0.5 μm.
Is preferred.

The intermediate layer preferably used in the present invention includes an intermediate layer using a curable metal resin obtained by thermosetting an organic metal compound such as a silane coupling agent and a titanium coupling agent. The film thickness of the intermediate layer using the curable metal resin is preferably 0.1 to 2 μm.

The intermediate layer preferably used in the present invention is an intermediate layer in which titanium oxide fine particles (average particle size: 0.01 to 1 μm) subjected to hydrophobic surface treatment are dispersed in a binder such as polyamide resin. To be The thickness of the intermediate layer is preferably 1 to 15 μm.

Photosensitive Layer The photosensitive layer structure of the photoconductor of the present invention may be a photosensitive layer structure of a single layer structure in which one layer has a charge generating function and a charge transporting function on the above-mentioned intermediate layer, but it is more preferable that the photosensitive layer is It is preferable that the function of the layer is separated into a charge generation layer (CGL) and a charge transport layer (CTL). By adopting a constitution in which the functions are separated, the 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. In the negative charging photoreceptor, the charge generation layer (C
GL) and a charge transport layer (CTL) thereon. In the case of the photoconductor for positive charging, the order of the layers is the reverse of that of the photoconductor for negative charging. The most preferable photosensitive layer structure of the present invention is a negatively charged photosensitive member structure having the above-mentioned function separation structure.

The constitution of the photosensitive layer of the function-separated negatively charged photoreceptor will be described below. Charge Generation Layer The charge generation layer contains a charge generation material (CGM). If necessary, a binder resin and other additives may be contained as other substances.

As the charge generating substance (CGM), a known charge generating substance (CGM) can be used. For example, a phthalocyanine pigment, an azo pigment, a perylene pigment, an azurenium pigment or the like can be used. Among these, CGM that can minimize the increase in residual potential with repeated use
Has a steric structure and a potential structure capable of forming a stable aggregation structure among a plurality of molecules, and specific examples thereof include a phthalocyanine pigment and a perylene pigment CGM having a specific crystal structure. For example, the Bragg angle 2θ with respect to Cu-Kα rays
CGMs such as titanyl phthalocyanine having a maximum peak at 27.2 ° and benzimidazole perylene having a maximum peak at 22.4 at 27.2 have almost no deterioration due to repeated use, and the residual potential increase can be reduced.

When a binder is used as a CGM dispersion medium in the charge generation layer, a known resin can be used as the binder, but the most preferable resin is a formal resin, a butyral resin, a silicone resin, a silicone-modified butyral resin, or a phenoxy resin. Resin etc. are mentioned. The ratio of the binder resin to the charge generating substance is preferably 20 to 600 parts by mass with respect to 100 parts by mass of the binder resin. By using these resins, the increase in residual potential due to repeated use can be minimized. The thickness of the charge generation layer is preferably 0.01 μm to 2 μm.

Charge Transport Layer When the charge transport layer is the surface layer of the organic photoreceptor, it is preferable that the charge transport layer contains the organic fine particles of the invention.

The charge transport layer contains a charge transport material (CTM) and a binder resin for dispersing CTM to form a film.
It is preferable that a resin such as polycarbonate is used as the binder resin, and an additive such as an antioxidant is contained as necessary as another substance.

As the charge transport material (CTM), a known charge transport material (CTM) can be used. For example, a triphenylamine derivative, a hydrazone compound, a styryl compound, a benzidine compound, a butadiene compound or the like can be used. These charge transport materials are usually dissolved in a suitable binder resin to form a layer. Among these, CTM that can minimize the increase in residual potential due to repeated use has high mobility and has a characteristic that the difference in ionization potential with CGM to be combined is 0.5 (eV) or less, and preferably 0. It is 0.25 (eV) or less.

The ionization potentials of CGM and CTM are measured by a surface analyzer AC-1 (manufactured by Riken Keiki Co., Ltd.).

When the charge transport layer is not the surface layer, examples of the resin used for the charge transport layer (CTL) include polystyrene, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, polyvinyl butyral resin, and epoxy resin. , Polyurethane resins, phenol resins, polyester resins, alkyd resins, polycarbonate resins, silicone resins, melamine resins, and copolymer resins containing two or more of the repeating units of these resins. Further, a high molecular weight organic semiconductor such as poly-N-vinylcarbazole may be used. Particularly, a polycarbonate resin is preferable for maintaining good electrophotographic characteristics (chargeability, sensitivity, etc.).

Surface Layer (Protective Layer) The organic fine particle solution obtained by the above-mentioned dispersion polymerization method is used as it is as a coating liquid for the surface layer, and the coating liquid is applied and dried to form the surface layer of the electrophotographic photoreceptor. Alternatively, the organic fine particle solution may be prepared by adding additives such as a charge-transporting substance, an antioxidant and a coating aid to prepare a surface layer coating solution, which is then dried by coating. You may form the surface layer of this. In order to maintain good electrophotographic properties (chargeability, sensitivity, etc.), it is more preferable to allow a charge transport layer, an antioxidant and the like to be present in the surface layer as well.

Further, it is preferable that the surface layer contains an antioxidant. The antioxidant is a typical one that does not prevent the action of oxygen on the auto-oxidizing substance existing in the organic photoreceptor or on the surface of the organic photoreceptor under the conditions of light, heat, discharge, etc. It is a substance that has an inhibitory property. Typically, the following compounds are listed.

[0063]

[Chemical 2]

[0064]

[Chemical 3]

[0065]

[Chemical 4]

[0066]

[Chemical 5]

Examples of the solvent or dispersion medium used for forming the intermediate layer, the photosensitive layer, the protective layer and the like include n-butylamine, diethylamine, ethylenediamine, isopropanolamine, triethanolamine, triethylenediamine,
N, N-dimethylformamide, acetone, methyl ethyl ketone, methyl isopropyl ketone, cyclohexanone, benzene, toluene, xylene, chloroform, dichloromethane, 1,2-dichloroethane, 1,2-dichloropropane, 1,1,2-trichloroethane, 1,
1,1-trichloroethane, trichloroethylene, tetrachloroethane, tetrahydrofuran, dioxolane,
Dioxane, methanol, ethanol, butanol, isopropanol, ethyl acetate, butyl acetate, dimethyl sulfoxide, methyl cellosolve and the like can be mentioned. The present invention is not limited to these, but dichloromethane, 1,2-dichloroethane, methyl ethyl ketone and the like are preferably used. Further, these solvents can be used alone or as a mixed solvent of two or more kinds.

Next, as a coating processing method for producing the electrophotographic photosensitive member of the present invention, dip coating, spray coating,
A coating method such as circular amount control type coating is used, but the coating process on the upper layer side of the photosensitive layer does not dissolve the lower layer film as much as possible, and in order to achieve uniform coating process, spray coating or circular amount control type ( A circular slide hopper type is a typical example. It is preferable to use a coating processing method such as coating. It is most preferable to use the circular amount-regulating type coating processing method for the resin layer of the present invention. The circular amount control type coating is described in detail, for example, in JP-A-58-189061.

Next, the image forming apparatus of the present invention will be described. FIG. 2 is a sectional view of an image forming apparatus as an example of the image forming method of the present invention.

In FIG. 2, reference numeral 50 denotes a photosensitive drum (photosensitive member) which is an image bearing member, and an organic photosensitive layer is applied onto the drum.
A photosensitive member having the resin layer of the present invention applied thereon is grounded and driven and rotated clockwise. Reference numeral 52 denotes a scorotron charger (charging means) for uniformly charging the peripheral surface of the photosensitive drum 50 by corona discharge. This charger 5
Prior to the charging by 2, the exposure may be performed by the pre-charge pre-exposure unit 51 using a light emitting diode or the like to eliminate the history of the photo conductor in the pre-image formation to eliminate the charge on the peripheral surface of the photo conductor.

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

Here, the reversal development process of the present invention means that the surface of the photoconductor is uniformly charged by the charger 52 to develop the image-exposed region, that is, the exposed portion potential (exposed portion region) of the photosensitive member. It is an image forming method that visualizes by a step (means). On the other hand, the unexposed portion potential is not developed by the developing bias potential applied to the developing sleeve 541.

The electrostatic latent image is then developed by the developing device 54 as a developing means. A developing device 54 containing a developer composed of toner and carrier is provided on the periphery of the photosensitive drum 50, and development is performed by a developing sleeve 541 that contains a magnet and holds the developer and rotates.
Inside the developing unit 54, the developer stirring and conveying members 544, 543,
The developer is constituted by a conveyance amount regulating member 542 and the like, and the developer is agitated and conveyed to be supplied to the developing sleeve, and the supply amount is controlled by the conveyance amount regulating member 542. The amount of the developer conveyed varies depending on the linear velocity of the applied organic electrophotographic photosensitive member and the specific gravity of the developer, but is generally 20 to 2
It is in the range of 00 mg / cm ² .

The developer is, for example, a carrier in which an insulating resin is coated around the above-mentioned ferrite core, a coloring agent such as carbon black and a charge control agent mainly composed of the above-mentioned styrene acrylic resin, and a charge control agent of the present invention. Colored particles consisting of low molecular weight polyolefin, and toner externally added with silica, titanium oxide, etc., the developer is transported to the developing zone with the layer thickness regulated by the transport amount regulating member, and development is carried out. . At this time, normally, a DC bias is applied between the photosensitive drum 50 and the developing sleeve 541, and if necessary, an AC bias voltage is applied to develop. Further, the developer is developed in a state of being in contact with or non-contacting with the photoreceptor. The potential sensor 547 measures the potential of the photoconductor.
Is provided above the developing position as shown in FIG.

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

In the transfer area, a transfer electrode (transfer means: transfer device) 58 operates on the peripheral surface of the photosensitive drum 50 in synchronization with the transfer timing, and the recording paper P fed is charged with a polarity opposite to that of the toner. To transfer the toner.

Next, the recording paper P is separated by a separating electrode (separator) 59.
Is discharged by the peripheral surface of the photoconductor drum 50 and conveyed to the fixing device 60. The heat roller 601 and the pressure roller 602 heat and pressurize the toner to fuse the toner, and then the paper is discharged from the outside of the device via the paper discharge roller 61. Is discharged to. The transfer electrode 58 and the separation electrode 59 stop the primary operation after passing the recording paper P and prepare for the next toner image formation. In FIG. 2, a transfer band electrode of a corotron is used as the transfer electrode 58. The setting condition of the transfer electrode varies depending on the process speed (peripheral speed) of the photoconductor and cannot be specified unconditionally. For example, the transfer current is +
100 to +400 μA, transfer voltage +500 to +
2000V can be used as the set value.

On the other hand, after the recording paper P is separated, the photosensitive drum 50 is subjected to pressure contact with a blade 621 of a cleaning device (cleaning means) 62 to remove and clean residual toner,
The pre-charging pre-exposure unit 51 again removes electricity and the charger 52 charges, and the next image forming process starts.

Reference numeral 70 denotes a removable process cartridge in which a photoconductor, a charger, a transfer device, a separator and a cleaning device are integrated.

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

[0081]

The present invention will be described in detail below with reference to examples, but the present invention is not limited thereto. In the following text, "part" means "part by mass".

(Synthesis Example 1) Polycarbonate "Iupilon Z300" (manufactured by Mitsubishi Gas Chemical Co., Inc.) 10.0 parts 2- (perfluorooctyl) ethylmethacrylate 4.0 parts Azobisisobutyronitrile (about every 2 hours) 0.03 parts each was added) Total 0.15 parts 1,3 dioxolane 100.0 parts The above composition was stirred and polymerized at about 65 ° C. for 10 hours under a nitrogen atmosphere. Dispersion polymer obtained as a result of polymerization (organic fine particles:
After adjusting the solid content concentration of the number average particle diameter of 50 nm) to 8% with 1,3 dioxolane, the following charge transporting substances were added to prepare coating solution 1 for surface layer.

[4- (2,2-Diphenylvinyl) phenyl] -di-p-tolylamine 9.0 parts 2,6-di-t-butyl-4-phenylphenol 0.18 parts (Synthesis example 2) Polycarbonate "Iupilon Z200" (manufactured by Mitsubishi Gas Chemical Co., Inc.) 10.0 parts 1H, 1H, 11H-Icosafluoroundecyl acrylate 3.0 parts Azobis- (2-methylbutyronitrile) 0.15 parts Toluene 90.0 Parts The above composition was polymerized by stirring at about 70 ° C. for 10 hours under a nitrogen atmosphere. Dispersion polymer obtained as a result of polymerization (organic fine particles:
Solid concentration of number average particle size 30nm) is 7% with toluene
Then, the following charge-transporting substances were added to prepare coating solution 2 for surface layer.

[4- (2,2-Diphenylvinyl) phenyl] -di-tolylamine 8.5 parts 2,6-di-t-butyl-4-phenylphenol 0.255 parts (Synthesis example 3) Polycarbonate "Iupilone" Z300 "5.0 parts 2- (perfluoro-9-methyloctyl) ethyl acrylate 5.0 parts Azobisisobutyronitrile (added 0.01 parts every about 2 hours) 0.05 parts in total 1, 2 Dichloroethane 50.0 parts Ethanol 5.0 parts The above composition was stirred and polymerized in a nitrogen atmosphere at about 70 ° C. for 10 hours. Dispersion polymer obtained as a result of polymerization (organic fine particles:
After adjusting the solid content concentration of the number average particle diameter of 120 nm) to 6.5% with 1,2 dichloroethane, the following charge transporting substances were added to prepare a coating solution 3 for surface layer.

[4- (2,2-Diphenylvinyl) phenyl] -di-tolylamine 6.7 parts 2,6-di-t-butyl-4-phenylphenol 0.134 parts (Synthesis example 4) Polycarbonate "TS2050" (Manufactured by Teijin Kasei Co., Ltd.) 5.0 parts Polycarbonate "Iupilon Z200" 5.0 parts 1H, 1H, 7H-dodecafluoropentyl acrylate 5.0 parts Divinylbenzene 0.1 part Azobis- (2-methylbutyro) Nitrile) 0.1 part 1,3 dioxolane 80.0 parts The above composition was stirred and polymerized in a nitrogen atmosphere at about 70 ° C. for 10 hours. Dispersion polymer obtained as a result of polymerization (organic fine particles:
After adjusting the solid content concentration of the number average particle diameter of 90 nm) to 6% with 1,2 dichloroethane, the following substances were added to prepare a coating solution 4 for surface layer.

[0086]   [4- (2,2-diphenylvinyl) phenyl] -di-tolylamine                                                           10.0 copies   0.2 parts of 2,6-di-t-butyl-4-phenylphenol   (Synthesis example 5)   Polycarbonate A (polycarbonate having the following structure: viscosity average molecular weight 3 × 10 ^Four ) 10.0 copies   1H, 1H, 9H-hexadecafluorononylmethacrylate 5.0 parts   1H, 1H, 11H-Icosafluoroundecyl acrylate 3.0 parts   Azobisisobutyronitrile (added 0.01 parts every 2 hours)                                                         0.05 copies   1,2 dichloroethane 95.0 parts   Isopropyl alcohol 5.0 parts Stir the above composition under a nitrogen atmosphere at about 75 ° C for 10 hours.
It matched. Dispersion polymer obtained as a result of polymerization (organic fine particles:
Number average particle size 70nm) solid concentration 1,2 dichloroe
After adjusting to 5% with tan, add the following substances for surface layer
The coating liquid 5 was used.

[0087]   [4- (2,2-diphenylvinyl) phenyl] -di-tolylamine                                                           15.0 copies   2,6-di-t-butyl-4-phenylphenol 0.3 part

[0088]

[Chemical 6]

Preparation of Photoreceptor 1 Photoreceptor 1 was prepared 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 Liquid> Polyamide resin “CM8000” (manufactured by Toray) 10.0 parts Titanium oxide “SMT500SAS” (manufactured by Teika) 30.0 parts Methanol 100.0 parts The above-mentioned circulation type wet disperser ( Dispermat SLC12
EX; VMA GETZMANN) was used for dispersion.

The following charge generation layer coating solution was applied onto the intermediate layer by dip coating to form a charge generation layer having a dry film thickness of 0.3 μm.

[0093]   <Charge generation layer coating liquid>   Charge generation material X-ray diffraction Bragg angle 2θ of 27.2 degrees, maximum peak 12.0 parts of titanyl phthalocyanine pigment having   Polyvinyl butyral resin "ESREC BL-1" (Sekisui Chemical Co., Ltd.)                                                               24.0 copies   T-Butyl acetate 300.0 parts The above was mixed and dispersed with a sand grinder.

The following charge transport layer coating solution and then the above surface layer coating solution 1 were continuously coated on the charge generation layer by a circular slide hopper, and the mixture was heated and cured at 110 ° C. for 60 minutes to obtain a dry film thickness. 20 μm charge transport layer and dry film thickness 5.0
A μm surface protective layer was formed.

<Charge Transport Layer Coating Liquid> [4- (2,2-diphenylvinyl) phenyl] -di-p-tolylamine 200.0 parts Polycarbonate "Iupilon Z300" (manufactured by Mitsubishi Gas Chemical Co., Inc.) 300.0 parts 2 , 6-di-t-butyl-4-phenylphenol 5.0 parts 1,2-dichloroethane 2000.0 parts Preparation of Photoreceptors 2-5 In the preparation of Photoreceptor 1, instead of surface layer coating liquid 1, surface Photosensitive member 2 in the same manner except that the layer coating liquids 2 to 5 were used.
~ 5 were produced.

Preparation of Photoreceptor 6 (Comparative Photoreceptor) A photoreceptor 6 was prepared in the same manner as the photoreceptor 1 except that the surface layer coating solution 1 was replaced by the surface layer coating solution 6 having the following composition.

Polycarbonate “Iupilon Z300” (manufactured by Mitsubishi Gas Chemical Co., Inc.) 14.0 parts [4- (2,2-diphenylvinyl) phenyl] -di-p-tolylamine 9.0 parts 2,6-di-t- Butyl-4-phenylphenol 0.18 parts 1,3 dioxolane 100.0 parts Preparation of Photoreceptor 7 (Comparative Photoreceptor) Instead of using the coating solution 1 for the surface layer, the coating solution 7 for the surface layer having the following composition was used. A photoconductor 7 was prepared in the same manner as the photoconductor 1.

Preparation of coating liquid 7 for surface layer (JP-A-8-32)
No. 8287 Example 1) First, in order to prepare a fluororesin particle dispersion liquid, 25
4-Fluoroethylene resin 200 heat treated at 0 ° C
Mass parts, 200 parts by mass of polycarbonate resin, 600 parts by mass of monochlorobenzene, 8 parts by mass of fluorine-type comb-type graft polymer (trade name GF300, manufactured by Toa Gosei Kagaku Co., Ltd.) were thoroughly mixed, and then sand using glass beads was used. Disperse with a grinder (manufactured by Amex Co., Ltd.), 4-fluoroethylene resin particle dispersion liquid (number average particle diameter: 310n)
m) was prepared.

Next, [4- (2,2-diphenylvinyl)]
[Phenyl] -di-p-tolylamine 1200 parts by mass, polycarbonate resin 800 parts by mass, 1500 parts by mass of the 4-fluorinated ethylene resin particle dispersion described above are dissolved and mixed in 5000 parts by mass of monochlorobenzene and 3000 parts by mass of dichloromethane to form a surface layer. Coating liquid 7 was prepared. A photoreceptor 7 was prepared in the same manner as the photoreceptor 1, except that the surface layer coating solution 7 was used instead of the surface layer coating solution 1.

Agglomeration rate of organic fine particles in the evaluation surface layer: Evaluation of N A section of a photoreceptor surface layer having a thickness of 0.3 ± 0.1 μm was prepared, and a cross section of the section was magnified 20,000 times (transmission electron microscope). (Photograph) was photographed, 5 arbitrary locations in the enlarged photograph were selected, and the aggregation rate was calculated by counting the organic particles and the agglomerated particles within an image area of 5 × 5 cm ² at each location.

Evaluation using a copying machine As an evaluation machine, a digital copying machine Konica manufactured by Konica
"Sitios 7075" (corona charging, laser exposure,
Reversal development, electrostatic transfer, nail separation, blade cleaning,
Has a cleaning auxiliary brush roller adoption process,
Using a printing speed of 75 sheets / min), the photoconductors 1 to 7 were mounted on the copying machine and evaluated. The cleaning property and the image evaluation were performed by copying an original image in which a character image having a pixel ratio of 7%, a human face photograph, a solid white image, and a solid black image are equally divided into A4 neutral papers. High temperature and high humidity environment (30 ° C, 80% R)
In H), 200,000 sheets were continuously copied, and a halftone image, a solid white image, and a solid black image were evaluated. However, before starting copying,
The surface of the photoconductor was sprinkled with setting powder, the photoconductor and the cleaning blade were made to conform to each other, and 200,000 copies were made. The evaluation items and evaluation criteria are shown below.

Evaluation Items and Evaluation Standards Image Density (Measured using RD-918 manufactured by Macbeth Co.).
The relative reflection density was measured with the reflection density of the paper being "0".
(Evaluated both at the initial stage and after copying 200,000 sheets) ◎: 1.2 or above both at the initial stage and after copying 200,000 sheets: Good ○: 1.0 or above at both the initial stage and after copying 200,000 sheets: Practical No Level x: 1.0 at least in the initial and after 200,000 copies
Less than: Level causing practical problems Fog: Judgment based on solid white image density Using a Macbeth reflection densitometer "RD-918", the density of unprinted copy paper (white paper) was measured at 20 locations with absolute image density. , And the average value is the blank sheet density. Next, the white background portion of the evaluation sheet on which the image was formed
Absolute image density was measured at 0 places, and the value obtained by subtracting the blank paper density from the average density was evaluated as the fog density.

A: 0 in both the initial stage and after copying 200,000 sheets.
005 or less (good) O: 0.01 or less both at the initial stage and after copying 200,000 sheets (at a level where there is no practical problem) X: At least one of the initial stage and after copying 200,000 sheets is 0.0
Greater than 1 (obviously, there is a problem in practical use) Sharpness Reproducibility of fine lines and sharpness of image after copying 200,000 sheets,
A character image was taken out and evaluated by crushing the character. 3 points, 5
A character image of points was formed and evaluated according to the following criteria.

⊚: 3 points, 5 points are clear and easily readable ○: 3 points are partially unreadable, 5 points are clear and easily readable Δ: 3 points are almost unreadable, 5 Point is readable x: 3 points are almost unreadable, and 5 points are partially or completely unreadable Toner transfer rate The transfer rate (%) was calculated by the following formula. However, when obtaining the transfer rate, the toner collected from the cleaning unit was not returned to the developing device but was taken in a bag.

Transfer rate (%) = {1- (mass of collected toner / mass of consumed toner)} × 100 Cleaning property (A after completion of copying 100,000 and 200,000 sheets)
10 sheets are continuously copied on 3 sheets, and it is judged by the presence or absence of the cleaning failure in the solid white area. ◎: No toner slipping up to 200,000 sheets ○: No toner slipping up to 100,000 sheets ×: 100,000 Toner slip-through occurs when the number of sheets is less than ◎: No squeal occurs up to 200,000 sheets ◯: Minor blade squeal occurs when the drum is stopped ×: Blade squeal occurs Cleaning cleaning blade starting torque measurement (s) and after 200,000 copies ), A torque gauge (MODEL 6BTG: manufactured by TOHNICHI) connected to the drum shaft of the main body of the copying machine was rotated, and the starting torque was measured. The measurement was performed 5 times and the average value was adopted.

Surface Contact Angle Measurement The surface contact angle of the photosensitive member was measured by using a contact angle meter (CA-DT • A type: manufactured by Kyowa Interface Science Co., Ltd.) for pure water. If the contact angle is small, deterioration of the surface of the photoconductor proceeds, and toner, paper dust, and the like tend to adhere.

Amount of Depletion of Photoreceptor Thickness The amount of depletion of the photoconductor was determined by calculating the difference between the average film thickness of the photoconductors measured at the start of the actual copying evaluation and at the end of copying 200,000 copies.

Film Thickness Measuring Method The film thickness of the photosensitive layer is determined by randomly measuring 10 points in the uniform film thickness portion, and taking the average value as the film thickness of the photosensitive layer. The film thickness measuring device is an eddy current type film thickness measuring device EDDY560C (HELMUT
FISCHER GMBTE CO.), And the difference in the thickness of the photosensitive layer before and after the actual copying test is taken as the amount of film thickness loss.

Other Evaluation Conditions Other evaluation conditions using the above 7075 were set to the following conditions.

Charging conditions Charging device: Scorotron charger, initial charging potential of -750
V exposure condition Set the exposure amount to make the exposed portion potential -50V.

Development conditions DC bias: -550V The developer is a carrier having a ferrite core as a core and coated with an insulating resin, a styrene acrylic resin as a main material, a colorant such as carbon black, a charge control agent, a low molecular weight of the present invention. A toner developer in which silica, titanium oxide, etc. are externally added to colored particles made of polyolefin is used. Transfer condition Transfer pole; Corona charging method Cleaning condition Cleaning part has hardness 70 °, impact resilience 65%, thickness 2
(Mm) and a cleaning blade having a free length of 9 mm were brought into contact with each other by a weight load method in the counter direction so as to have a linear pressure of 18 (N / m).

The evaluation results are shown in Table 1.

[0113]

[Table 1]

As is clear from Table 1, photoreceptors 1 to 1 each having a surface layer containing the polymer obtained by the dispersion polymerization method of the present invention
No. 5 shows good image characteristics, toner transfer rate, and cleaning characteristics. Further, it is found that the photoconductors 1 to 5 have smaller starting torque of the cleaning blade and the surface is slippery than the photoconductor 6 of the surface layer having no polymer by the dispersion polymerization method. As a result, the amount of wear of the film thickness of the photoconductor is also 1
5 to 5 are smaller than the photoconductor 6. Further, the photoconductor 6 has sharpness, toner transfer rate, and cleaning property.
Is inferior to. Since the agglomeration rate of the organic fine particles in the surface layer of the photoconductor 7 is 17%, the film properties of the surface layer are not uniform, the amount of film thickness loss is large, and the image density is reduced. Further, the sharpness and the cleaning property are inferior to those of the photoconductors 1 to 5.

[0115]

As is apparent from the examples, by using the constitution of the present invention, it is possible to provide a highly durable electrophotographic photosensitive member with improved cleaning properties and blade squeal. Further, it is possible to provide an image forming method, an image forming apparatus and a process cartridge which can achieve a good electrophotographic image using the electrophotographic photosensitive member.

[Brief description of drawings]

FIG. 1 is a diagram illustrating an aggregation rate.

FIG. 2 is a sectional view of an image forming apparatus as an example of the image forming method of the present invention.

[Explanation of symbols]

50 photoconductor drum (or photoconductor) 51 Pre-charge exposure unit 52 Charger 53 Image exposure device 54 Developer 541 Development sleeve 543,544 developer stirring and conveying member 547 potential sensor 57 Paper Feed Roller 58 transfer electrode 59 Separation electrode (separator) 60 fixing device 61 Paper ejection roller 62 cleaning device 70 Process cartridge

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Mao Asano             2970 Ishikawa-cho, Hachioji-shi, Tokyo Konica stock             In the company F-term (reference) 2H068 AA04 AA08 AA14 AA28 AA35                       AA37 BB02                 2H134 GA01 HD17 KG08 KH05 KH15

Claims (8)

[Claims] 1. An electrophotographic photoreceptor comprising a conductive support and a layer containing organic fine particles having an agglomeration rate: N (%) in the following range. 0 ≦ N ≦ 10 2. An intermediate layer, a charge generation layer, and a conductive support,
An electrophotographic photoreceptor having a charge transport layer and a surface layer, wherein the surface layer contains organic fine particles having an agglomeration ratio: N (%) in the following range. 0 ≦ N ≦ 10 3. The number average particle diameter of the organic fine particles is 10 to 10.
The electrophotographic photosensitive member according to claim 1, which has a thickness of 5000 nm. 4. The electrophotographic photosensitive member according to claim 1, wherein the organic fine particles are synthesized by a dispersion polymerization method. 5. The electrophotographic photosensitive member according to claim 1, wherein a contact angle of the surface of the electrophotographic photosensitive member with respect to pure water is 90 to 120 °. 6. An image forming method, wherein an electrophotographic image is formed using the electrophotographic photosensitive member according to any one of claims 1 to 5. 7. An image forming apparatus, wherein an electrophotographic image is formed using the image forming method according to claim 6. 8. An electrophotographic photosensitive member according to claim 1 and a charging device, an image exposing device, a developing device,
A process cartridge comprising at least one of a transfer device and a cleaning device, which is configured to be able to be taken in and out of an image forming apparatus.