JPH08328273A - Electrophotographic photoreceptor, image forming method and image forming device - Google Patents

Abstract

PURPOSE: To obtain an electrophotographic photoreceptor less liable to the wear and damage of the surface layer in a process for repeatedly forming images, less liable to the deterioration of the electrophotographic performance due to fatigue and stably giving a high density clear color image, and to provide a color image forming method and a color image forming device. CONSTITUTION: In this image forming method, plural toner images are formed in a superposed state on an electrophotographic photoreceptor with a substrate during one revolution and the toner images are simultaneously transferred and fixed on a transfer material to form the objective color image. This electrophotographic photoreceptor used in this image forming method has a layer contg. inorg. particles in the top layer.

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, an image forming method and an image forming apparatus used in an image forming method capable of forming a color image by one rotation of the electrophotographic photosensitive member.

[0002]

2. Description of the Related Art Conventionally, in order to form a color image based on the Carlson method, as described in, for example, Japanese Unexamined Patent Publication (Kokai) No. 61-27560 (publication 1), a photosensitive layer provided on an aluminum drum is provided. A single charging device, an exposing device, and a plurality of developing devices are arranged on the outer circumference of the body, and a plurality of color toner images are superposed on the photosensitive layer by a plurality of rotations of the photoconductor, and the toner images are transferred. There is known a so-called multi-pass type image forming method in which a color image is formed by collectively transferring and fixing on a material.

According to the image forming method of the above publication 1, there is an advantage that the overlaying accuracy of the toner images of the respective colors is high and a color image having no color shift is easily obtained, but the color image is formed by one rotation of the photoconductor. Since it is not possible, there is a problem that the image forming speed is slow and the work efficiency is poor.

Further, in the image method of Publication 1, the peripheral length of the photosensitive drum is required to be equal to or longer than the peripheral length of the transfer material. For example, when the transfer material of A3 size is used, the diameter of the photosensitive drum is 180.
There is also a problem that the apparatus becomes large in size because it requires ~ 200 mm.

Therefore, for example, in Japanese Unexamined Patent Publication (Kokai) No. 5-307307 (publication 2), a plurality of charging devices and developing devices are arranged on the outer periphery of a photoconductor having an endless transparent support, and a plurality of LEDs are provided inside the photoconductor. An image forming method and an apparatus for forming a color image by arranging an exposure device and rotating the photosensitive member (one pass) have been proposed.

According to the technique of the publication 2, compared with the publication 1, the photoreceptor can be a small-diameter photoreceptor having a diameter of 120 mmφ or less, and the exposure device can be built in the photoreceptor. Therefore, downsizing and downsizing of the apparatus can be achieved, and since a color image can be formed in one pass, simplification and speeding up of the process can be achieved.

[0007]

However, in the image forming method and the apparatus thereof disclosed in the publication 2, unlike the case of the publication 1, the cleaning is required to be performed once unlike the case where the cleaning is performed once for a plurality of rotations of the photosensitive member. Yes, and image formation is relatively fast. Therefore, the uppermost layer of the photoconductor is easily worn or damaged during the repeated image formation to deteriorate the electrophotographic performance, and image defects are likely to occur.

The degree of wear and damage of the photoconductor is further increased in the case of an organic photoconductor using an organic photoconductive substance.

Further, when performing digital image exposure using monochromatic light such as an LED as in the case of the above-mentioned publication 2, interference occurs at the interface between the photoconductor and the support, which causes interference fringes called moire on the image. May occur.

Furthermore, in the image forming method and the apparatus thereof disclosed in the publication 2, image exposure is performed from the inside of the photoconductor, but at that time, the light absorptivity of the photoconductor is insufficient, and the transmitted light is a device around the photoconductor. Alternatively, it may be reflected by the inner wall of the apparatus to form image unevenness or a ghost image on the photoconductor.

The present invention has been proposed in view of the above circumstances, and an object of the present invention is to reduce the abrasion and damage of the surface layer of the photoconductor during the process of repeated image formation, and to improve the electrophotographic performance of the photoconductor. (EN) Provided are an electrophotographic photoreceptor, a color image forming method, and an apparatus thereof, which can stably obtain a high-density and clear color image with less fatigue deterioration.

Another object of the present invention is to provide an image forming method and an apparatus thereof which are compact in size and capable of forming a color image at high speed.

[0013]

The above object can be achieved by the following constitution.

1) A plurality of toner images are superposed on each other during one rotation on an electrophotographic photosensitive member having a support, and the toner images are collectively transferred and fixed on a transfer material to form a color image. The electrophotographic photosensitive member used in the image forming method described above, wherein the uppermost layer of the photosensitive member has a layer containing inorganic particles.

2) The electrophotographic photosensitive member described in 1 above, wherein the Mohs hardness of the inorganic particles is 5 or more.

3) The electrophotographic photosensitive member according to 1 or 2 above, wherein the inorganic particles are substantially spherical.

4) The electrophotographic photosensitive member according to any one of 1 to 3 above, wherein the layer containing the inorganic particles contains a hindered phenol derivative or a hindered amine derivative as an antioxidant.

5) The electrophotographic photosensitive member described in any one of 1 to 4 above, wherein the inorganic particles are silica particles.

6) The electrophotographic photosensitive member described in any one of 1 to 5 above, wherein the endless support is transparent.

7) The electrophotographic photosensitive member described in any one of 1 to 6 above, wherein the light transmittance of the photosensitive member with respect to the light source light is 20% or less.

8) The electrophotographic photosensitive member according to any one of 1 to 7 above, a plurality of charging units, a plurality of image exposing units, and a plurality of developing units, and the photosensitive member by each unit. An image forming method characterized in that a plurality of toner images are superposed on each other by one rotation of the photoconductor, and the toner images are collectively transferred and fixed on a transfer material to form a color image.

9) The electrophotographic photosensitive member according to any one of 1 to 7 above, a plurality of charging units, a plurality of image exposing units, and a plurality of developing units, and the photosensitive member by each unit. An image forming apparatus, wherein a plurality of toner images are superposed on each other by one rotation of the photoconductor, and the toner images are collectively transferred and fixed on a transfer material to form a color image.

The present invention will be described in more detail. The electrophotographic photoreceptor of the present invention may be either an inorganic photoreceptor using an inorganic photoconductive substance such as cadmium sulfide, selenium, or amorphous silicon, or an organic photoreceptor using an organic photoconductive substance, without toxicity. An organic photoconductor that is low in cost and excellent in processability and has a high degree of freedom in selection depending on the application is preferably used.

The photosensitive member used in the present invention is, for example, a cylindrical photosensitive member shown in FIG. 1A or a belt photosensitive member shown in FIG. 1B, and the support of the photosensitive member may be transparent or opaque. Although it is good, a belt-shaped photoreceptor using a transparent support, preferably a cylindrical photoreceptor.

In the process of repeatedly forming a color image on the photoconductor, in order to provide the photoconductor with excellent durability without image defects and fatigue deterioration, the uppermost layer thereof is provided with inorganic particles and, if necessary, oxidation. An inhibitor (AO agent) is contained.

Here, the uppermost layer of the photoreceptor is, for example, a protective layer provided on the photosensitive layer or a charge transport layer forming the uppermost layer of the photosensitive layer, and more preferably the charge transport layer is a plurality of layers. Consists of the top layer.

The inorganic particles contained in the uppermost layer are preferably those having a Mohs hardness of 5 or more, which do not adversely affect the electrophotographic performance.

Examples of such inorganic particles include oxides such as cerium oxide, chromium oxide, aluminum oxide, magnesium oxide, silicon oxide, tin oxide, zirconium oxide, iron oxide and titanium oxide; calcium sulfate, barium sulfate and sulfuric acid. Sulfates such as aluminum; silicates such as calcium silicate and magnesium silicate; nitrides such as boron nitride and titanium nitride; silicon carbide, titanium carbide,
Carbides such as boron carbide, tungsten carbide and zirconium carbide; borides such as zirconium boride and titanium boride may be mentioned, and one or more of these may be used in combination.

The inorganic particles have a volume average particle diameter of 0.05 to
2.0 μm, preferably a ratio of major axis / minor axis of 2.0
Less than substantially spherical particles.

The volume average particle diameter of the inorganic particles is 0.05 μm.
When it is less than m, sufficient mechanical strength of the surface of the photoconductor is not obtained, and the surface area of the particles is increased, resulting in an increase in water absorption amount, and the photoconductor surface is abraded or damaged in the process of repeated image formation, resulting in electron emission. Photo performance deteriorates. On the other hand, if it exceeds 2.0 μm, the surface roughness of the photoconductor becomes large and the cleaning blade is worn or damaged to deteriorate the cleaning characteristics, resulting in poor cleaning and easy occurrence of image blur.

The term "substantially spherical particles" means that the particles are not indefinite in shape and have a major axis / minor axis ratio of 2 when enlarged to a size (diameter 1 to 10 mm) whose surface shape can be discriminated by an electron microscope or the like. It is a spherical particle of less than 0.0, and has a smooth surface shape without unevenness. The term “smooth particles” as used herein means particles that quantitatively have the depth or height of the irregularities on the particle surface of 1/10 or less of the radius (or short diameter).

In this case, the coefficient of friction on the surface of the photosensitive member can be reduced, and it is possible to prevent the reversal of the cleaning blade, which has been a problem in the prior art.

The volume average particle diameter of the inorganic particles is measured by a laser diffraction / scattering type particle size distribution measuring apparatus LA-700 (manufactured by Horiba Ltd.).

The inorganic particles are treated with a coupling agent such as a silane coupling agent or a titanium coupling agent or a hydrophobizing agent such as a higher fatty acid or a metal salt thereof in order to make the particles hydrophobic. Is preferred.

Examples of the titanium coupling agent include tetrabutyl titanate, tetraoctyl titanate, isopropyl triisostearoyl titanate, isopropyl tridecylbenzene sulfonyl titanate, bis (dioctyl pyrophosphate) oxyacetate titanate and the like. Further, as the silane coupling agent, γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ- (2-aminoethyl) aminopropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, N-β- (N-vinylbenzylaminoethyl) γ-aminopropyltrimethoxysilane hydrochloride, hexamethyldisilazane, methyltrimethoxysilane, butyltrimethoxysilane, isobutyltrimethoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane, decyltrimethoxysilane Methoxysilane, dodecyltrimethoxysilane, phenyltrimethoxysilane, o-methylphenyltrimethoxysilane, p
-Methylphenyltrimethoxysilane and the like. The fatty acids and metal salts thereof include undecylic acid, lauric acid, tridecanoic acid, myristic acid, palmitic acid, pentadecanoic acid, stearic acid, heptadecanoic acid, arachidic acid, montanic acid, oleic acid, linoleic acid, arachidonic acid and the like. Long-chain fatty acids are listed, and their metal salts are zinc, iron, magnesium, aluminum,
Examples thereof include salts with metals such as calcium, sodium and lithium.

As the inorganic particles contained in the uppermost layer of the photoconductor used in the present invention, silica particles are particularly preferable. Among the silica particles, there are few hydrophilic groups on the particle surface and the hygroscopicity is small. What is obtained is preferable, for example, what is obtained by the following manufacturing methods is preferable.

For example, chemical flame CVD (Chemical Flame)
It is produced by the Vapor Deposition method, but among them, it is preferable to introduce the metallic silicon powder into a mixed gas for combustion, and explosively combust and react it.

Details of this manufacturing method are described in, for example, JP-A-60-2.
55602, JP-A-5-193908 and 5-19.
No. 3909, No. 5-193910, No. 5-19392
No. 8, No. 5-196614, and No. 6-107406.

In the manufacturing method described in each of the above-mentioned publications, the raw material silicon metal material is washed with high-purity water a plurality of times in advance to remove dissolved components, and at the same time, heat treatment is performed to remove gas phase components and increase the temperature. A fine silicon powder is obtained. Next, a combustible gas such as LPG and a combustion-supporting gas such as oxygen gas are introduced into a burner at the head of the manufacturing apparatus to form a flame for ignition, and the high-purity silicon powder is added during the ignition flame. A carrier gas such as air containing dispersed is introduced to start ignition and combustion. After that, the combustion-supporting gas is supplied in multiple stages to explosively oxidize and burn the silicon powder to obtain high-purity silica particles.

The silica particles obtained by the above-mentioned production method may be further hydrophobized with the hydrophobizing agent.

Next, a hindered phenol derivative or a hindered amine derivative is preferably used as the AO agent optionally contained in the uppermost layer of the photoreceptor used in the present invention, and specific examples of the compound are shown below.

[0042]

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[0043]

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The photoreceptor used in the present invention is not particularly limited, but is preferably an organic photoreceptor, for example, as shown in FIG.
The photoconductor has a layer structure of (C), (D) or (V). The layer structure of the photoreceptor of FIG.
The transparent conductive layer 2, the intermediate layer 3, the charge generation layer (CGL) 4 and the charge transport layer (CTL) 5 are laminated in this order, and the layer structure of the photoreceptor of FIG. 2D is shown in FIG. The protective layer 6 is provided on the CTL 5 of the photoconductor of FIG.
The layer structure of the photoconductor of (e) is the CGL of the photoconductor of (c) of FIG.
4, a first charge transport layer (CTL) 7 is provided, and a second charge transport layer (CTL) 8 is further provided thereon. Therefore, needless to say, the uppermost layer in FIG. 2 is CTL5 for (c), protective layer 6 for (d), and CTL8 for (e), respectively.

The content of the inorganic particles contained in the uppermost layer of the photoreceptor is 0.01 to 50 based on the total weight of the uppermost layer.
% Is preferable, and 0.05-40% is more preferable. Further, the content of the inorganic particles is preferably set so that the film strength of the uppermost layer of the photoreceptor used in the present invention is 0.1 to 1.0 μm based on the following measurement method.

Measurement of film strength: Using a HEIDON-18 type surface property measuring machine (manufactured by Shinto Kagaku Co., Ltd.), a diamond needle (semicircular shape with a tip radius of 0.3 mm) having a vertical load of 200 g was placed on the uppermost layer of the photoreceptor. The uppermost layer is scratched by moving horizontally under pressure at a speed of 10 mm / sec. The depth of the scratch is measured with a laser microscope (Lasertec).

The film strength of the uppermost layer changes not only with the inorganic particles contained in the uppermost layer but also with the kind of the binder resin. It is also necessary to adjust the quantity.

The depth of scratches representing the film strength is 0.1 μm.
If it is smaller, the surface strength of the photoconductor is too strong, the cleaning member is worn or damaged, the cleaning action is gradually reduced, and as a result, the photoconductor is easily deteriorated due to fatigue.

On the other hand, the depth of scratches indicating the film strength is 1.0 μm.
If it is larger than m, the film strength of the photoconductor is not sufficient, and the uppermost layer of the photoconductor is easily scratched and abraded.

Examples of the charge transport material (CTM) contained in the photosensitive layer of each of the photoreceptors shown in FIGS. 2 (c) to 2 (e) are, for example, oxazole derivatives, oxadiazole derivatives, thiazole derivatives, thiadiazole derivatives, triazole derivatives. , Imidazole derivative, imidazolone derivative, imidazoline derivative, bisimidazolidine derivative, styryl compound, hydrazone compound, benzidine compound, pyrazoline derivative, stilbene compound, amine derivative, oxazolone derivative, benzothiazole derivative, benzimidazole derivative, quinazoline derivative, benzofuran derivative,
Acridine derivative, phenazine derivative, aminostilbene derivative, poly-N-vinylcarbazole, poly-1-
Vinyl pyrene, poly-9-vinyl anthracene, etc. are mentioned, and these CTMs are usually layer-formed with a binder.

Examples of particularly preferable specific compounds of CTM among the above CTMs are shown below.

[0052]

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[0053]

[Chemical 4]

CGM contained in the CGL of each photoreceptor
As, for example, phthalocyanine pigments, polycyclic quinone pigments, azo pigments, perylene pigments, indigo pigments, quinacridone pigments, azurenium pigments, squarylium dyes, cyanine dyes, pyrylium dyes, thiopyrylium dyes, xanthene dyes, triphenylmethane dyes, styryl dyes, etc. These CGMs may be layered alone or together with a suitable binder resin.

Next, as the binder resin contained in the CGL, CTL and protective layer 6 of each photoconductor, polyester resin, polystyrene resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polycarbonate resin. , Polyvinyl butyral resin, polyvinyl acetate resin, styrene-butadiene resin, vinylidene chloride-acrylonitrile copolymer resin, vinyl chloride-maleic anhydride copolymer resin, urethane resin, silicone resin epoxy resin, silicone-alkyd resin, phenol resin, Examples thereof include polysilane resin and polyvinyl carbazole.

However, the binder resin contained in the CTL 5 of FIG. 2C, the protective layer 6 of FIG. 2D and the CTL 8 of FIG. 2E which form the uppermost layer of each of the photoreceptors is preferably mechanical. A material that is strong against impact and has high abrasion resistance and does not impair electrophotographic performance is preferable. Examples of preferred binder resins include polycarbonate resins having structural units represented by the following general formulas [I] to [IV].

[0057]

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In the formula, R _{1 to} R ₈ and R _{11 to} R ₁₈ each independently represent a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a cycloalkyl group or an aryl group. , Z represents an atom group forming a saturated or unsaturated carbon ring having 4 to 11, and R ₉ represents a hydrogen atom, an alkyl group having 1 to 9 carbon atoms or an aryl group.

[0059]

[Chemical 6]

(In the formula, R _{21 to} R ₂₈ and R _{31 to} R ₄₆ are each independently a hydrogen atom, a halogen atom, or a carbon number of 1 to 10).
Represents a substituted or unsubstituted alkyl group, cycloalkyl group, or aryl group, and k and m are integers, and k / m is selected to be 1 to 10.

The polycarbonate resin having the structural unit represented by the above general formula preferably has a weight average molecular weight of 3
It is said to be more than 10,000. For example, Iupilon Z
200 (mw 50,000), Z300 (mw 80,000),
Z400, Z800 (Mitsubishi Gas Chemical), TS2050
(Mw 150,000) (Teijin Kasei) and the like are commercially available and can be preferably used.

Next, as a solvent or a dispersion medium used in forming each of the layers, 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 −
Examples thereof include trichloroethane, trichloroethylene, tetrachloroethane, tetrahydrofuran, dioxane, methanol, ethanol, isopropinal, ethyl acetate, butyl acetate, dimethylsulfoxide, and methyl cellosolve. The present invention is not limited to these, but when a ketone solvent is used, the sensitivity and potential change during repeated use are further improved. Further, these solvents may be used alone or as a mixed solvent of two or more kinds.

CG of the electrophotographic photosensitive member used in the present invention
The weight ratio of CGM to binder resin in L4 is preferably 1: 5 to 5: 1, but the binder resin in CGL4 is not always necessary, and the thickness of CGL4 is 5 μm.
Hereinafter, the thickness is preferably 0.05 to 2 μm.

The ratio of CTM to binder resin in CTL5, CTL7 and CTL8 is 5: 1 to weight ratio.
1: 5 is preferable, and the film thickness of CTL5 and CTL7 is 5
50 μm, preferably 10 to 40 μm, and CTL8
Has a thickness of 0.5 to 40 μm, preferably 1 to 30 μm.

The thickness of the protective layer 6 is 0.2 to 20 μm.
m, preferably 0.5 to 10 μm.

Next, the support 1 of the photosensitive member used in the present invention
There is a transparent cylindrical support or a transparent belt-like support, but a transparent cylindrical support is important, and as the support, robustness, impact resistance, abrasion resistance, temperature and humidity resistance, dimensional accuracy, etc. It is preferable that the cross section is excellent and the cross section is close to a perfect circle. Further, since it has excellent light transmittance with respect to light from a light source such as an LED, preferably having a light transmittance of 80% or more, glass, quartz or a plastic material is used. The material is mainly used.

Examples of the plastic materials include polyacrylic acid alkyl esters such as polymethylmethacrylate, polyethylmethacrylate and polybutylacrylate, polystyrene, polyimide, polyester, polyvinyl chloride, polycarbonate or polyethylene terephthalate. . Among them, the transparent cylindrical support using polymethacrylic acid alkyl ester has high strength and excellent light transmission property, and thus is suitable for an image forming apparatus adopting a mechanism of performing exposure from the inside of the photoconductor. ing.

Next, the transparent conductive layer 2 provided on the transparent cylindrical support 1 has a light transmittance of 80 with respect to the light from the light source.
% Or more, it is preferable that the variation in the light transmittance depending on the location is within 10%.

The transparent conductive layer 2 is obtained by uniformly depositing a metal or its alloy on the support 1 by a method such as vapor deposition, sputtering, glow discharge, plasma, CVD or plating, and the film thickness thereof. Is 0.01 to 10 μ
m.

As the metal, Al, Au, Ag, C
u, Ni, Co, Ti, Zn, Cr, In, Sn, Pb
Alternatively, it is a metal selected from Fe or the like or a compound thereof, and the metal oxide is SnO ₂ , In ₂ O ₃ , I
TO etc. are mentioned.

Further, the transparent conductive layer 2 may be a conductive polymer or a fine powder of the metal, alloy, metal oxide or diamond type crystalline carbon dispersed in a binder resin.

CGL of the transparent conductive layer 2 and the photosensitive layer 9
An intermediate layer 3 having a barrier function and an adhesive action can be provided between the intermediate layer 3 and the intermediate layer 3.

The material of the intermediate layer 3 is casein,
Polyvinyl alcohol, nitrocellulose, ethylene-
Examples thereof include acrylic acid copolymers, polyvinyl butyral, phenol resin polyamides (nylon 6, nylon 66, nylon 610, copolymerized nylon, alkoxymethylated nylon, etc.), polyurethane, gelatin and aluminum oxide. The thickness of the intermediate layer 2 is 0.1 to 10 μm.
m is preferable, and 0.1 to 5 μm is particularly preferable.

Next, as a coating method for producing the electrophotographic photosensitive member of the present invention, dip coating, spray coating,
Although coating processing methods such as circular amount control type coating are used, the coating process on the surface layer side of the photosensitive layer does not dissolve the lower layer film as much as possible, and spray coating or circular amount control type coating to achieve uniform coating process. It is preferable to use a coating processing method such as. Regarding the spray coating, for example, JP-A-3-
90250 and JP-A-3-269238, and the circular amount control type coating is described in detail, for example, in JP-A-58-189061.

According to the spray coating and the circular amount regulation coating, as compared with the dip coating or the like, the coating liquid is not wasted, the lower layer is not dissolved or damaged, and uniform coating is achieved. And so on.

The photoconductor used in the present invention having the above-mentioned structure is uniformly charged on its surface by the charging means arranged outside the photoconductor as described later.
Image exposure is performed from the inside by an image exposing unit arranged inside the photoconductor to form an electrostatic latent image, and image formation is performed by developing the latent electrostatic image by a developing unit arranged outside the photoconductor.

Therefore, when the image exposure from the inside of the photosensitive member is not sufficiently absorbed by the photosensitive layer and a considerable amount of light is transmitted onto the photosensitive member, it is diffusely reflected by the charging unit, the developing unit or the inner wall surface of the apparatus, and the image is formed. Image unevenness and a ghost image are formed on the upper part, so that a good color image cannot be obtained.

Therefore, in the present invention, CGL constituting the photoconductor is
It is preferable that the transmittance of the light source light to the photoconductor is 20% or less by selecting the CGM therein, the film thickness of the CGL, the particle size of the inorganic particles in the uppermost layer, the addition amount, and the like.

The inorganic particles in the uppermost layer also have an effect of preventing moire when the light source light is monochromatic light such as LED light.

Next, the developers used in the image forming method and apparatus of the present invention include a one-component developer containing a magnetic toner as a main component or a non-magnetic toner and a two-component developer containing a magnetic carrier as a main component. The toner in these developers is colored particles having an average particle diameter of 5 to 30 μm, which is obtained by dispersing and containing a colorant and other necessary additives in a binder resin.

In the present invention, the toner may optionally contain an inorganic fluidizing agent having a primary average particle size of less than 0.2 μm. When the primary average particle diameter of the inorganic fluidizing agent is larger than 0.2 μm, the contribution to the fluidity of development is reduced, and the surface of the photoreceptor is easily worn or damaged.

The content of the fluidizing agent added as necessary in the toner is preferably 0.05 to 5.0% by weight,
When the content is less than 0.05% by weight, the contribution of fluidity to the developer becomes insufficient, and when the content is more than 5.0% by weight, the photoconductor is easily damaged and dot-like image defects are likely to occur. Become.

Examples of the inorganic fluidizing agent include fine particles of metal oxides such as silica, alumina, titania, calcium oxide, magnesium oxide, barium oxide, beryllium oxide, cerium oxide and iron oxide, and metal oxides thereof. Examples thereof include those obtained by subjecting the above-mentioned fine particles to a hydrophobic treatment. In particular, when a hydrophobized material is used, the moisture resistance of the fluidizing agent is improved, so that a stable fluidizing action can be obtained even in a high humidity atmosphere. Such a hydrophobizing treatment includes, for example, metal oxide fine particles as described above,
For example, it can be carried out by reacting with a hydrophobizing agent such as dialkyldihalogenated silane, trialkylhalogenated silane, alkyltrihalogenated silane, and hexanealkyldisilazane at high temperature.

Among the various products mentioned above, hydrophobic silica is particularly preferably used.

Examples of the hinder of the toner used in the present invention include homopolymers of styrene such as polystyrene, poly-p-chlorostyrene, and polyvinyltoluene, and their substitution products, styrene-p-chlorostyrene copolymers, and styrene-propylene copolymers. Polymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-acrylic acid Octyl copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile Copolymer, styrene-vinyl polymer Styrene-based copolymers such as polyether copolymers, styrene-vinyl ethyl ether copolymers, styrene-vinyl methyl ketone copolymers, styrene-butadiene copolymers, styrene-isoprene copolymers, styrene-acrylonitrile-indene copolymers Polymer, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, silicone resin, polyester, polyurethane, polyamide, epoxy resin polyvinyl butyral,
Rosin, modified rosin, terbene resin, phenol resin,
Examples thereof include xylene resin, aliphatic or alicyclic hydrocarbon resin, and aromatic petroleum resin. These resins can be used alone or in combination of two or more.

In addition to the colorant, the toner used in the present invention may contain a charge control agent, an anti-offset agent, a magnetic substance and other property improving agents usually used in the toner, if necessary.

Examples of the colorant include carbon black and nigrosine dye (C.I. No. 50415).
B), aniline blue (C.I. No. 50405),
Alco oil blue (CI No. azoic Bl
ue 3), chrome yellow (C.I. No. 1409)
0), Ultramarine Blue (C.I. No. 7710)
3), DuPont Oil Red (C.I. No. 2610)
5), quinoline yellow (C.I. No. 4700)
5), methylene blue chloride (C.I. No. 52)
015), phthalocyanine blue (C.I. No. 74)
160), malachite green oxalate (C.I.
No. 42000), lamp black (C.I.No.
77266), Rose Bengal (C.I. No. 454)
35), mixtures of these, and the like. The colorant is preferably contained in a sufficient ratio so that a visible image having a sufficient density is formed.
About 1 to 20 parts by weight is preferable with respect to 00 parts by weight.

As the negatively chargeable charge control agent, for example, a metal complex of aromatic oxycarboxylic acid or aromatic dicarboxylic acid or a sulfonylamine derivative, a sulfonamide derivative, a sulfonic acid derivative or a sulfonate derivative of copper phthalocyanine is used. Can be mentioned.

Examples of the positively chargeable charge control agent include, for example, quaternary ammonium compounds, alkylpyridinium compounds, alkylpicolinium compounds and nigrosine SO.
Alternatively, a nigrosine-based dye such as nigrosine EX can be used.

Examples of the anti-offset agent include olefin polymers or copolymers having a low softening point such as polyethylene and polypropylene, other fatty acid esters or partial saponification products thereof, alkylenebisfatty acid amides, higher fatty acids or salts thereof or higher alcohols. Can be mentioned.

Such offset preventing agents can be used alone or in combination of two or more, and the use ratio thereof is preferably 1 to 20% by weight, more preferably 1 to 10% by weight, based on the binder. Is.

In the case where the toner is a magnetic toner of a one-component developer, the magnetic substance contained in the toner includes a ferromagnet such as ferrite, magnetite, a ferromagnet such as iron, cobalt and nickel, or an alloy thereof, or an element thereof. Compounds or alloys containing no ferromagnetic element but exhibiting ferromagnetism by appropriate heat treatment, for example, Heusler alloys containing manganese and copper such as manganese-copper-aluminum and manganese-copper-tin. Examples may include alloys of the type, or chromium dioxide, and the like. These magnetic materials are used in the form of fine powder having an average particle size of 0.1 to 1 micron, and the ratio thereof is preferably 20 to 70 parts by weight, more preferably 40 to 70 parts by weight, per 100 parts by weight of the toner. .

The carrier used when the developer used in the present invention is a two-component developer is not particularly limited, but examples thereof include reduced iron powder, ferrite powder, and the surface of these particles such as styrene-acrylic resin and silicone. resin,
Those coated with a resin such as a fluororesin, those obtained by dispersing and containing magnetic particles in a binder composed of these resins, and the like are used.

The image forming method and apparatus of the present invention using the photoconductor having the above construction will be described below by taking the color printer of FIG. 3 as an example.

In the figure, 10 is a photoreceptor having the layer structure of FIG. 2 (e), for example, and the transparent conductive layer 2, the intermediate layer 3 and the transparent conductive layer 2 are provided on the outer periphery of the cylindrical support 1 formed of an alkyl methacrylate ester resin. CGL4, first charge transport layer CTL-
7 and the second charge transport layer CTL-8 in this order as an organic photoreceptor.

110Y, 110M, 110C and 11
0K is yellow (Y), magenta (M), cyan (C)
In the scorotron charging device used for the image forming process of each color of black and black (K), the organic photoconductive layer of the photoconductor 10 is charged by corona discharge in order to hold a charge of a predetermined potential, and the photoconductor 10 is charged. A uniform electric potential is applied to.

12Y, 12M, 12C and 12K are
It has FL (phosphor emission), EL (electroluminescence), PL (plasma discharge), LED (light emitting diode), and an optical shutter function in which light emitting elements arranged in the axial direction of the photoconductor 10 are arranged in a line in an array. LISA (photomagnetic effect shutter array) in which elements are arranged in a line, PLZT
An exposure optical system, which is an image exposure apparatus configured as a unit including an exposure element such as a (transmissive piezoelectric element shutter array) and an LCS (liquid crystal shutter), and a self-occ lens serving as an equal-magnification imaging element. The image signals of the respective colors read by the image reading device are sequentially taken out from the memory and input as electric signals to the exposure optical systems 12Y, 12M, 12C and 12K. The exposure optical systems 12Y, 12M, 12C, and 12K are all attached to a cylindrical holding member 20 and are attached to the photoreceptor 10.
Is housed inside the base body of.

13Y, 13M, 13C and 13K are developing devices which are non-contact developing devices for accommodating yellow (Y), magenta (M), cyan (C) and black (K) developers. The developing sleeve 1 rotates in the same direction with a predetermined gap from the peripheral surface of the photoconductor 10.
30Y, 130M, 130C and 130K.

The developing devices 13Y, 13M, 13C and 13K are the corona charging devices 110Y and 110 described above.
M, 110C and 110K charging and exposure optical system 1
The electrostatic latent image formed on the photoconductor 10 by image exposure with 2Y, 12M, 12C and 12K is reversely developed in a non-contact state by applying a developing bias voltage.

As the original image, an image read by an image pickup device or an image edited by a computer is temporarily used as an image signal for each color of Y, M, C and K in an image reading device separate from this device. Stored and stored in memory.

When the image recording is started, the photoconductor driving motor is started to rotate the photoconductor 10 in the clockwise direction, and at the same time, the photoconductor 10 is charged by the corona charging device 110Y.
Application of electric potential is started.

After a potential is applied to the photoconductor 10, the exposure optical system 12Y starts exposure by an electric signal corresponding to the first color signal, that is, an image signal of yellow (Y), and the drum is rotationally scanned to expose the photoconductor 10. An electrostatic latent image corresponding to the yellow (Y) image of the original image is formed on the photosensitive layer on the surface.

The latent image is reversely developed by the developing device 13Y with the developer on the developing sleeve in a non-contact state, and a yellow (Y) toner image is formed according to the rotation of the photosensitive drum 10.

Then, the photosensitive drum 10 is further covered with the corona charging device 110M on the yellow (Y) toner image.
Is applied with a potential by the charging action of the exposure optical system 12M, the exposure is performed by an electric signal corresponding to the second color signal of the exposure optical system 12M, that is, the image signal of magenta (M), and the non-contact reversal development is performed by the developing device 13M. A magenta (M) toner image is sequentially formed on the yellow (Y) toner image.

A recorona charging device 11 is manufactured by the same process.
0C, the exposure optical system 12C and the developing device 13C further convert a cyan (C) toner image corresponding to the third color signal into a fourth color signal by the corona charging device 110K, the exposure optical system 12K and the developing device 13K. Corresponding black (K) toner images are sequentially superposed and formed, and a color toner image is formed on the peripheral surface of the photosensitive drum 10 within one rotation.

These exposure optical systems 12Y, 12M, 12C
The exposure of the organic photosensitive layer of the photoconductor drum 10 by 12K and 12K is performed from the inside of the substrate through the transparent substrate. Therefore, the exposure of the image corresponding to the second, third, and fourth color signals is performed without any influence of the toner image previously formed, and is equivalent to the image corresponding to the first color signal. It is possible to form an electrostatic latent image. In order to stabilize the temperature inside the photoconductor drum and prevent the temperature rise due to the heat generated by the exposure optical systems 12Y, 12M, 12C and 12K, a material having good thermal conductivity is used for the holding member 20, and a heater is used at low temperature. In the case of high temperature, it is possible to suppress the heat to the outside by taking measures such as radiating heat to the outside through a heat pipe. Further, in the developing operation by the developing devices 13Y, 13M, 13C and 13K, the developing sleeves 130Y, 130M,
A developing bias in which a direct current or an alternating current is applied to 130C and 130K is applied, and jumping development is performed by a one-component or two-component developer accommodated in the developing device, so that the photoconductor 10 that grounds the transparent conductive layer is grounded. On the other hand, a non-contact reversal development in which a DC bias having the same polarity as that of the toner is applied to attach the toner to the exposed portion is performed. Thus, the color toner image formed on the peripheral surface of the photosensitive drum is sent from the paper feeding cassette 15 by the sending roller 15a in the transfer device 14a,
The retiming roller 1 by the pair of transport rollers 15b and 15c
6 and is driven by the timing roller 16
It is transferred onto a transfer paper P that is a transfer material that is fed in synchronization with the toner image on the photoconductor 10.

The transfer paper P on which the toner image has been transferred is removed from the charge by the static eliminator 14b and separated from the peripheral surface of the drum, and then conveyed to the fixing device 17 by the conveying plate 14C. After the toner is fused and fixed on the transfer paper P by being heated and pressure-bonded between the fixing roller 17a and the pressure-bonding roller 17b, the toner is discharged from the fixing device 17 by the fixing outlet roller pair 17d, and is conveyed by the paper discharge conveying roller pair 18a. The sheet was discharged onto the sheet discharge tray 200 at the upper part of the apparatus through the paper roller 18, but the one using the above-described photosensitive substrate of the present invention provided a clear and excellent image.

On the other hand, the photoconductor 10 from which the transfer paper has been separated is cleaned by the cleaning blade 19a in the cleaning device 19.
Thus, the surface of the photoconductor 10 is rubbed to remove and clean residual toner, and the toner image of the original image is continuously formed or is temporarily stopped to form a new toner image of the original image. The waste toner scraped off by the cleaning blade 19a is removed by the toner transport screw 19b.
It is discharged to a waste toner container (not shown).

Since the photoconductor 10 has the exposure optical system accommodated therein, even if the diameter of the drum is relatively small,
A plurality of corona charging devices 110 described above are provided on the outer peripheral surface thereof.
Y, 110M, 110C and 110K, developing device 13
Y, 13M, 13C, 13K and the like can be provided, and the volume of the device can be made compact by using a small diameter drum having an outer diameter of 30 mm to 150 mm.

In the above description, an example of a digital color printer has been described, but the image forming method and the apparatus thereof of the present invention are not limited to this, and may be an image forming apparatus such as a digital or analog type color copying machine. Alternatively, the non-contact reversal development method has been described as the development method, but the non-contact regular development method, the contact reversal development method, or the contact regular development method may be used.

[0111]

EXAMPLES The present invention will be specifically described below with reference to examples, but the embodiments of the present invention are not limited thereto.

<Inorganic particles P1 to P3> Spherical silica particles “SOC1” manufactured by Madmatex Co., which has been subjected to a hydrophobic treatment with a silane coupling agent having a volume average particle size of 0.2 μm, and also a volume average particle size manufactured by Madmatex. Hydrophobized spherical silica particles "SOC2" of 0.5 µm and hydrophobized spherical titanium oxide particles "A-100" of Ishihara Sangyo Co., Ltd. having a volume average particle diameter of 0.15 µm were used as inorganic particles P1 and P2, respectively. And P3.

<Production of Photoreceptor 1> On a 100 mmφ cylindrical transparent support made of methacrylic acid methyl ester resin,
A transparent conductive layer having a transmittance of 90% for light from a light source (LED) and a thickness of 500Å was formed.

Next, a copolymer type polyamide resin "CM-8000" (manufactured by Toray Industries, Inc.) 1.5 is formed on the transparent conductive layer.
A coating solution prepared by dissolving 90 parts by weight of a solvent in a mixed solvent of 90 parts by weight of methanol and 10 parts by weight of butanol was applied by dip coating to form an intermediate layer having a film thickness of 0.3 μm. Next, polyvinyl butyral resin "ESREC BX-L" (Sekisui Chemical Co., Ltd.)
0.8 parts by weight of MGM was dissolved in a mixed solvent of 80 parts by weight of methyl ethyl ketone and 20 parts by weight of cyclohexanone, and CGM4 composed of a perylene pigment having the following structure was added to the resulting solution.
A coating solution obtained by mixing and dispersing parts by weight was applied onto the intermediate layer by dip coating to form a CGL having a thickness of 0.2 μm after drying.

[0115]

[Chemical 7]

Then, a polycarbonate resin "Iupilon Z300" (mw 8.44 × 1) as a binder was used.
0 ⁴ ) (manufactured by Mitsubishi Gas Chemical Co., Inc.), 10 parts by weight of Exemplified Compound (T-10) as CTM, and 0.1% of Exemplified Compound (A) -3 as a hindered phenol AO agent.
A coating solution prepared by dissolving 25 parts by weight of methylene chloride in 100 parts by weight of methylene chloride was dip-coated on the CGL to form a first CTL having a film thickness of 20 μm after drying.

Next, 1.5 parts by weight of a polycarbonate resin "Iupilon Z300" as a binder, 0.15 parts by weight of the inorganic particles P1, 1 part by weight of an exemplary compound (T-10) as CTM and a hindered phenol. A coating solution obtained by dissolving and dispersing 0.025 parts by weight of Exemplified Compound (A) -3 as a system AO agent in 100 parts by weight of ethyl chloride is applied onto the first CTL using a circular amount control type coating machine. A second CTL having a film thickness after drying of 5 μm was formed to obtain a photoconductor 1. The depth of scratches representing the film strength of the present photoreceptor based on the above-mentioned measurement method was 0.5 μm. The red LED light (Ga, Al, As, LED) (λm
The transmittance for ax≈635 nm) was 16%.
The light transmittance of the photoconductor to the light source is Hitachi U-35.
It measured by the measuring method using the integrating sphere prescribed | regulated to JIS K7105 using the 00 type spectrophotometer.

<Production of Photoreceptor 2> Second CT of Photoreceptor 1
A photoconductor 2 was obtained in the same manner as the photoconductor 1 except that 0.70 parts by weight of the inorganic particles P2 was used instead of the inorganic particles P1 contained in L. The depth of scratches representing the film strength of the present photoreceptor based on the above-mentioned measurement method was 0.2 μm.

The transmittance of the present photoconductor for red LED light was 14%.

<Production of Photoreceptor 3> Second CT of Photoreceptor 1
A photoconductor 3 was obtained in the same manner as the photoconductor 1 except that 0.10 parts by weight of the inorganic particles P3 was used instead of the inorganic particles P1 contained in L. The depth of scratches representing the film strength of the present photoreceptor based on the above-mentioned measurement method was 0.7 μm. The red LE of this photoconductor
The transmittance for D light was 17%.

<Production of Photoreceptor 4> Second CT of Photoreceptor 1
A photoconductor 4 was obtained in the same manner as the photoconductor 1 except that the inorganic particles P1 contained in L were removed. The depth of the scratch on the photoconductor, which represents the film strength based on the above-described measurement method, was 3.0 μm. The transmittance of the present photoconductor for red LED light was 18%.

<Production of Developer Group 1> 100 parts by weight of styrene-acrylic resin was mixed with chrome yellow (C.
I. No. 14090) 10 parts by weight, 1 part by weight of an azo charge control agent and 3 parts by weight of a polyolefin as an offset preventing agent are melt-kneaded, cooled, pulverized and classified to obtain particles having an average particle size of 10 μm. Then, 1.0 wt% of hydrophobic silica particles "R-972" (manufactured by Nippon Aerosil Co., Ltd.) was added as a fluidizing agent to obtain a Y toner.

Next, 4 parts by weight of the Y toner was mixed with 96 parts by weight of a carrier composed of ferrite particles coated with a styrene acrylic resin and having an average particle size of 80 μm to obtain a Y developer.

Further, instead of the colorant chrome yellow, DuPont oil red (CI. No. 26105), phthalocyanine blue (CI. No. 74160) and lamp black (CI. No. 77266) are respectively used. M developer, C developer and K developer were obtained in the same manner as the Y developer except that it was used.

<Preparation of Developer Group 2 and Group 3> Hydrophobic silica particles "R-805" and "R" manufactured by Nippon Aerosil Co., Ltd. were used in place of the hydrophobic silica particles "R-972" as the fluidizing agent.
The second developer group and the third developer group were obtained in the same manner as the first developer group except that "-811" was used.

Example 1 The photoconductor 1 was mounted as the photoconductor drum 10 in the color printer shown in FIG. 3, and the A4 plate 1 was used in the atmosphere of 20 ° C. and RH 60% based on the image forming method of the color printer.
A color print test was performed 100,000 times at a print speed of 0 sheets / minute.

The developing devices 13Y, 13M, 13 shown in FIG.
C and 13K are respectively filled with the respective developers of Y, M, C, and K, and the chargers 110Y and 110 are charged.
A scorotron charger is used for M, 110C and 110K, and each of the exposure units 12Y, 12M, 12C and 12 is used.
K has a red LED (Ga, Al, As, λmax≈63
5 nm) was used.

Further, the charging of -700 V is applied to each of the photoconductor drums 10 by each charger, and each electrostatic latent image formed by the image exposure of 400 dpi from each of the LED exposure units has a DC bias of -600 V. 5kHz, 3KV A
An image was formed by developing by the non-contact reversal developing method by each of the developing devices to which the C bias was applied.

As a result, from the first time to the 100,000th time, there was no image defect and a high density and clear color print image was obtained.

Examples 2 and 3 When the photoconductor 2 is used as the photoconductor and the developer of the second group is used as the developer in the color printer, and when the photoconductor 3 is used and the developer of the third group is used as the developer. As a result of performing two kinds of color print tests using a developer 100,000 times as in Example 1, each print has clear image without image defects from 1 to 100,000 times. The image was obtained.

Comparative Examples 1 and 2 10 was carried out in the same manner as in Example 1 except that the above-mentioned group 1 of developing agents were used as the developing agent and the above-mentioned group 1 of developing agents was used as the photosensitive element of the color printer. As a result of conducting a color print test for comparison over 10,000 times, a weak moire occurred in the image quality at the first time, and many fine scratches were generated in the color print image at the 100,000th time, and the image was unclear. .

[0132]

As is apparent from the above description, according to the image forming method and the image forming apparatus of the present invention, there is no image defect due to abrasion and damage of the photoconductor during the process of repeatedly forming color images, and the image forming apparatus can be used all the time. It is possible to obtain an effect that a high density and clear color image can be obtained, and the apparatus can be made compact and high speed.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a form of a photoconductor.

FIG. 2 is a cross-sectional view showing a layer structure of a photoconductor.

FIG. 3 is a cross-sectional view of a color printer.

[Explanation of symbols]

1 Transparent Support 2 Transparent Conductive Layer 3 Intermediate Layer 4 Charge Generation Layer (CGL) 5 Charge Transport Layer (CTL) 6 Protective Layer 7 First Charge Transport Layer 8 Second Charge Transport Layer 10 Photoreceptor Drums 12Y, 12M, 12C, 12K yellow (Y), magenta (M), cyan (C), black (K) exposure unit 13Y, 13M, 13C, 13K Y, M, C, K developing unit 110Y, 110M, 110C, 110K Y , M, C, K charger 15 Paper feed cassette 16 Timing roller 17 Fixing device 19 Cleaning device

Claims (9)

[Claims] 1. A color image is formed by superposing a plurality of toner images in a single rotation on an electrophotographic photosensitive member having an endless support, and transferring and fixing the toner images onto a transfer material at once. An electrophotographic photosensitive member used in an image forming method to be formed, comprising an inorganic particle-containing layer as an uppermost layer of the photosensitive member. 2. The electrophotographic photosensitive member according to claim 1, wherein the inorganic particles have a Mohs hardness of 5 or more. 3. The electrophotographic photosensitive member according to claim 1, wherein the inorganic particles are substantially spherical. 4. The electrophotographic photosensitive member according to claim 1, wherein the layer containing the inorganic particles contains a hindered phenol derivative or a hindered amine derivative as an antioxidant. 5. The electrophotographic photosensitive member according to claim 1, wherein the inorganic particles are silica particles. 6. The electrophotographic photosensitive member according to claim 1, wherein the endless support is transparent. 7. The electrophotographic photoconductor according to claim 1, wherein the photoconductor has a light transmittance of 20% or less with respect to light from a light source. 8. An electrophotographic photosensitive member according to claim 1, comprising a plurality of charging means, a plurality of image exposing means, and a plurality of developing means, and the photosensitive means by each of the means. A plurality of toner images are superposed on the body by one rotation of the photoconductor, and the toner images are collectively transferred onto a transfer material.
An image forming method, which comprises fixing and forming a color image. 9. An electrophotographic photosensitive member according to claim 1, comprising a plurality of charging means, a plurality of image exposing means, and a plurality of developing means, and the photosensitive means by each of the means. A plurality of toner images are superposed on the body by one rotation of the photoconductor, and the toner images are collectively transferred onto a transfer material.
An image forming apparatus characterized by fixing and forming a color image.