JPH0260180B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel image forming method using a photoreceptor made of an organic photoconductor (OPC). Inorganic photoconductive materials such as selenium, cadmium sulfide, and zinc oxide are known as photoconductive materials used in electrophotographic photoreceptors. These photoconductive materials have a number of advantages, such as being able to be charged to a suitable potential in the dark, having less charge dissipation in the dark,
Alternatively, although it has advantages such as being able to rapidly dissipate charges by irradiation with light, it also has various disadvantages. For example, selenium-based photoreceptors easily crystallize due to factors such as temperature, humidity, dust, and pressure. Especially when the ambient temperature exceeds 40°C, crystallization becomes significant, resulting in decreased charging performance and white spots on images. There is a drawback when this occurs. Furthermore, selenium-based photoreceptors and cadmium sulfide-based photoreceptors have the disadvantage that stable sensitivity and durability cannot be obtained when used under high humidity over time. In addition, zinc oxide photoreceptors require the sensitizing effect of sensitizing dyes such as rose bengal, but such sensitizing dyes cause charge deterioration due to corona charging and photobleaching due to exposure light, so it may take a long time. It has the disadvantage that it cannot provide a stable image over a long period of time. On the other hand, various organic photoconductive polymers including polyvinylcarbazole have been proposed, but these polymers have poor film formability, light weight, high productivity, etc. compared to the inorganic photoconductive materials mentioned above. Despite their superiority, it has been difficult to put them into practical use until now because they are inferior to inorganic photoconductive materials in terms of sensitivity, durability, and stability against environmental changes. Moreover, a suitable sensitizer capable of achieving a sufficiently high sensitivity has not yet been found. For this reason, in recent years, many low molecular weight organic photoconductive substances have been developed to replace polymer-based organic photoconductive substances. The advantage of low molecular weight organic photoconductive substances is that the range of compounds that can be selected has expanded, and by selecting those with good sensitivity and charge retention,
This means that it has become possible to improve the drawbacks of conventional photoreceptors using organic photoconductive polymers. As mentioned above, photoreceptors made of organic photoconductors, both low-molecular and high-molecular ones, have excellent properties, but on the other hand, they have the disadvantage of having a low surface hardness and being easily scratched. And, because of this, the surface of the photoreceptor cannot be strongly cleaned.
Because it is difficult to remove low-resistance substances generated on the surface of the photoreceptor due to corona discharge, paper dust, and other low-resistance substances adhering to the surface, these substances absorb moisture, especially in high-temperature, high-humidity environments, and the resistance becomes extremely low. It has the disadvantage that the latent image tends to be disturbed due to the lowering of the latent image. After examining various methods to overcome these drawbacks of OPC photoreceptors, we found that fine particles with appropriate hardness for OPC photoreceptors, such as magnetic powder with a particle size of approximately 0.1 to 2μ, were used as a binder. It has been found that it is effective to use powder in dispersed form. On the other hand, the present applicant previously proposed a new developing method in Japanese Patent Application Laid-open No. 43036/1983. This involves applying a very thin layer of magnetic toner onto the sleep surface, triboelectrically charging it, and then placing it in close proximity to the electrostatic image under the action of a magnetic field, facing it without contact.
It is to be developed. According to this method, by applying an extremely thin layer of magnetic toner onto the sleeve, the chances of contact between the sleeve and the toner are increased, and sufficient frictional electrification is possible.The toner is supported by magnetic force, and the magnet By moving the toner particles relative to each other, the toner particles are disaggregated and are sufficiently rubbed against the sleeve, and the toner is supported by magnetic force and is developed by facing the electrostatic image without coming into contact with it. By doing so, excellent images can be obtained by preventing background fog. However, although this method uses a magnetic toner, when applied to an OPC photoreceptor, the above-mentioned disturbance of the latent image could not be resolved. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an image forming method that overcomes the above-mentioned defects and does not cause disturbance of latent images even under high temperature and high humidity environments. Specifically, the present invention includes a charging step of negatively charging a laminated organic photoconductive photoconductor having a surface hardness of 12 to 100 g, and a step of negatively charging the laminated organic photoconductive photoconductor with a surface hardness of 12 to 100 g. A latent image forming process in which a latent image is formed, and a BET specific surface area of 2 to 20 m ² /
A volume average particle size of 8 to 100 g containing magnetic powder having a particle size of
A substantially non-magnetic toner containing 50μ magnetic particles and a styrene copolymer as a binder resin, and a nitrogen adsorption method that is externally added to the non-magnetic toner.
a step of forming a layer of a developer containing fine silica powder having a BET specific surface area of 0.5 to 500 m ² /g; and bringing the developer layer into contact with a laminated organic photoconductive photoreceptor holding a latent image. a developing step of forming a toner image of non-magnetic toner on the laminated organic photoconductive photoreceptor; a step of transferring the toner image of the non-magnetic toner onto the laminated organic photoconductive photoreceptor; An image forming method comprising: a step of cleaning a blade. Regarding. In contrast to the above-mentioned method, the method of the present invention uses OPC
It is assumed that the reason why the disadvantage of photoconductor's tendency to cause disturbance of the latent image can be overcome is because the developer layer comes into contact with the OPC photoconductor, thereby removing the low-resistance material on the photoconductor. . As the organic photoconductor used in the present invention, a laminated type photoreceptor consisting of a charge transport layer and a charge generation layer is preferably used in the present invention. azo pigments, algol yellow, pyrene quinone, quinone pigments such as indanthrene brilliant violet RRP, quinocyanine pigments, perylene pigments, indigo pigments such as indigo, thioindigo, bisbenzimidazole pigments such as India First Orange Toner, copper phthalocyanine It is formed by dispersing charge-generating substances such as phthalocyanine pigments and quinacridine pigments in a binder resin such as polyester, polystyrene, polyvinyl butyral, polyvinylpyrrolidone, methylcellulose, polyacrylic acid esters, and cellulose ester. Its thickness is 0.01
-1μ, preferably about 0.05-0.5μ. In addition, the charge transport layer may contain polycyclic aromatic compounds such as anthracene, pyrene, phenanthrene, coronene, indole, carbazole, etc. in the main chain or side chain.
Oxazole, isoxazole, thiazole,
imidazole, pyrazole, oxadiazole,
It is formed by dissolving a hole-transporting substance such as a compound having a nitrogen-containing cyclic compound such as pyrazoline, thiadiazole, or triazole, or a hydrazone compound in a resin that has film-forming properties. This is because the charge transporting substance generally has a low molecular weight and has poor biofilm properties by itself. Examples of such resins include polycarbonates, polymethacrylates, polyarylates, polystyrene, polyesters, polysulfones, styrene-acrylonitrile copolymers, styrene-methyl methacrylate copolymers, and the like. The thickness of the charge transport layer is preferably 5 to 20 microns. Properties such as abrasion resistance and oil lubricity are also important for the resin constituting the surface layer of the photoreceptor such as the charge transport layer, but in order to effectively achieve the purpose of the present invention, resins that constitute the surface layer of the photoreceptor are It is preferable that the Tg at the measured peak position is 60°C or higher, particularly 80°C or higher. In addition, the surface hardness of the OPC photoreceptor used in the present invention is 12 to 100 g as measured by the method shown below.
It is preferable that The above hardness is measured as follows. For example, fix the OPC photoreceptor to the sample stage of a HEIDON14 surface property measuring machine (manufactured by Shinto Kagaku),
A vertical load xg is applied to the OPC photoreceptor through a diamond needle (conical, with a cone angle of 90°, but the tip is semispherical with a diameter of 0.01mm), and the sample stage is rotated at a rate of 50mm/min. move at a speed of The width of this scratch is measured using, for example, a microscope attached to a microhardness meter MVK-F (manufactured by Akashi Seisakusho). The above operation is performed with the load xg being 10g, 15g, etc.
Repeat this process by changing 20g, 25g, 30g, 35g, 40g, etc. From the linear regression relationship between the scratch width and load, calculate the load that will cause a 50μ scratch and use it as the hardness of the OPC photoreceptor. If the OPC photoreceptor is a drum, the OPC photoreceptor is set on the sample so that scratches are made in the axial direction of the drum. Furthermore, those containing a vinyl polymer at least 30% by weight, preferably at least 50% by weight, particularly preferably at least 70% by weight are preferred. The vinyl polymer is a monopolymer of vinyl monomers or a copolymer of two or more vinyl monomers, and vinyl monomers include styrene, P-chlorostyrene, vinyltoluene, methyl methacrylate, acrylonitrile, Examples include N-vinylcarbazole, and may also be a copolymer with a monomer such as a diene monomer that can be polymerized with a vinyl monomer. The magnetic particles used in the present invention are composed of magnetic powder and a binder, and the magnetic powder is made of a substance that is magnetized when placed in a magnetic field. There are metal powders, alloys and compounds such as magnetite, γ-Fe ₂ O ₃ and ferrite. These magnetic powders are preferably subjected to organic treatment such as coupling treatment. In particular, in order to exhibit the above-mentioned effects, it is preferable that the BET specific surface area by the nitrogen adsorption method be 2 to 20.
m ² /g, especially 2.5 to 12 m ² /g is good. As the binder, known thermoplastic resins, thermosetting resins, etc. can be used. The content of the magnetic powder is preferably 10 to 80% by weight, particularly 30 to 75% by weight based on the weight of the magnetic particles. The volume average diameter of the magnetic particles is preferably about 8 to 50 μm, particularly 10 to 30 μm. In the image forming method of the present invention, a substantially non-magnetic toner is used as the toner, as shown in Examples below. The binder resin for the toner used in the present invention is as follows:
Monopolymers of styrene and its substituted products such as polystyrene, poly-P-chlorostyrene, and polyvinyltoluene; styrene-P-chlorostyrene copolymers, styrene-propylene copolymers, styrene-
Vinyl toluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer,
Styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene- α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer,
Styrenic copolymers such as styrene-butadiene copolymer, styrene-isobrene copolymer, styrene-acrylonitrile-indene copolymer, styrene-maleic acid copolymer, and styrene-maleic acid ester copolymer; polymethyl Methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, polyurethane, polyamide, epoxy resin, polyvinyl butyral, polyacrylic acid resin, rosin, modified rosin, terpene resin, phenolic resin, aliphatic or fatty resin Cyclic hydrocarbon resin, aromatic petroleum resin, chlorinated paraffin,
Parafine wax, carnauba wax, etc. can be used alone or in combination, but in order to achieve the object of the present invention, styrene-based polymers containing styrene or styrene-substituted products are preferred. Particularly preferred are copolymers of styrene or vinyltoluene and acrylic esters or methacrylic esters. Furthermore, the developer used in the present invention has a BET specific surface area of 0.5 to 500 m ² /g, especially 50 m 2 /g, determined by nitrogen adsorption method.
It is preferable to add ~400 m ² /g of non-magnetic inorganic fine powder. This is because the addition of such fine powder reduces the aforementioned disturbance of the latent image. This is thought to be because such fine powder has a large specific surface area, so that the low-resistance substance adhering to the drum is adsorbed or attached to its surface and removed. Examples of such non-magnetic inorganic fine powder include alumina, titanium dioxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, silica sand, clay, mica, wollastonite, and diatomaceous earth. , various inorganic oxide pigments, chromium oxide, cerium oxide, red iron, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silica fine powder, etc., but silica fine powder is particularly preferred. The silica fine powder referred to herein is a fine powder having Si--O--Si bonds, and includes both those manufactured by a dry method and those manufactured by a wet method.
Various conventionally known methods can be applied to produce fine silica powder by a wet method. For example, the decomposition of sodium silicate by acid can be expressed using the general reaction formula (the reaction formula is omitted below): Na ₂ O.xSiO ₂ +HCl+H ₂ O→SiO ₂・nH ₂ O+
Decomposition of sodium silicate with ammonia salts or alkali salts such as NaCl, generation of alkaline earth metal silicate from sodium silicate, followed by decomposition with acid to form silicic acid, ion exchange of sodium silicate solution There are methods such as using resin to make silicic acid, and using natural silicic acid or silicate. The silica fine powder referred to herein can be any of anhydrous silicon dioxide (silica) and other silicates such as aluminum silicate, sodium silicate, potassium silicate, magnesium silicate, and zinc silicate. The particle size is the average primary particle size,
It is desirable that it be within the range of 0.01 to 2μ. Also, it is desirable that the material contains 85% by weight or more of SiO ₂ . The silica fine powder obtained by the dry process is so-called dry process silica or fumed silica, and is produced by a conventionally known technique. For example, this method utilizes a thermal decomposition oxidation reaction of silicon tetrachloride gas in an oxyhydrogen flame, and the basic reaction formula is as follows. SiCl ₄ +2H ₂ +O ₂ →SiO ₂ +4HCl Also, in this manufacturing process, for example, by using other metal halide compounds such as aluminum chloride or titanium chloride together with silicon halide, a composite fine powder of silica and other metal oxides can be produced. It is also possible to obtain the body, and the present invention includes these as well. Its particle size is 0.001~2μ as the average primary particle size.
It is desirable that it be within the range of, particularly preferably,
It is preferable to use silica fine powder within the range of 0.002 to 0.2μ. Specifically, these silica fine powders include:
There are various commercially available silicas, but those with hydrophobic groups on the surface are preferred, such as R-972 (manufactured by Aerosil), Taranox 500 (manufactured by Talco), other silane coupling agents, titanium coupling agents,
It is preferable to use silicone oil or one treated with silicone oil having an amine in its side chain. Particularly when the magnetic toner is a toner for developing a negative latent image, it is preferable to use positively chargeable silica fine powder. Further, the positively chargeable silica fine powder preferably has a triboelectric charge amount of +10 μc/g or more, particularly preferably +30 μc/g or more, as determined by the following measurement. Here, the positively chargeable silica fine powder is defined as follows. i.e. 25℃ 50~60%RH
2g of fine silica powder left overnight in an environment of
98 g of non-resin-coated carrier iron powder (for example, EFV200/300 manufactured by Nippon Tetsuko Co., Ltd.) having a main particle size of 200 to 300 mesh was placed in an aluminum pot with a volume of approximately 200 c.c. under the above environment. Mix thoroughly (shake it up and down approximately 50 times by holding it in your hand) and measure the tribocharge amount of the fine silica powder using the usual blow-off method using an aluminum cell with a 400 mesh screen. . A silica fine powder whose triboelectric charge measured by this method is positive is defined as a positively charged silica fine powder. In order to obtain such positively charged silica fine powder, it is preferable to treat it with a coupling agent containing an amine or silicone oil. Such treatment agents include, for example, H ₂ NCH ₂ CH ₂ CH ₂ Si (OCH ₃ ) ₃ H ₂ NCH ₂ CH ₂ CH ₂ Si (OC ₂ H ₅ ) ₃ K1200 K1201 H ₂ NCONHCH ₂ CH ₂ CH ₂ Si (OC ₂ H ₅ ) ₃ H ₂ NCH ₂ CH ₂ NHCH ₂ CH ₂ CH ₂ Si (OCH ₃ ) ₃ H ₂ NCH ₂ CH ₂ NHCH ₂ CH ₂ NHCH ₂ CH ₂ CH ₂ Si
(OCH ₃ ) ₃ H ₅ C ₂ OCOCH ₂ CH ₂ NHCH ₂ CH ₂ CH ₂ Si (OCH ₃ ) ₃ H ₅ C ₂ OCOCH ₂ CH ₂ NHCH ₂ CH ₂ NHCH ₂ CH ₂ CH ₂
Si(OCH ₃ ) ₃ H ₅ C ₂ OCOCH ₂ CH ₂ NHCH ₂ CH ₂ NHCH ₂ CH ₂ NH
CH ₂ CH ₂ NH・ ・CH ₂ CH ₂ CH ₂ Si (OCH ₃ ) ₃ H ₃ COCOCH ₂ CH ₂ NHCH ₂ CH ₂ NHCH ₂ CH ₂ CH ₂ S
i (OCH ₃ ) ₃ K1202 K1203 K1204 K1205 K1206 K1207 K1208 K1209 (H ₃ CO) ₃ SiCH ₂ CH ₂ CH ₂ −NHCH ₂ (H ₃ CO) ₃ SiCH ₂ CH ₂ CH ₂ −NHCH ₂ K1210 H ₃ CNHCH ₂ CH ₂ CH ₂ Si (OC ₂ H ₅ ) ₃ H ₂ N (CH ₂ CH ₂ NH) ₂ CH ₂ CH ₂ CH ₂ Si (OCH ₃ ) ₃ H ₃ C−NHCONHC ₃ H ₆ Si (OCH ₃ ) ₃ etc. An aminosilane coupling agent, generally a modified silicone oil having an amine in the side chain of the following formula, is used. K1211 (where R ₁ represents hydrogen, an alkyl group, an aryl group, or an alkoxy group, R ₂ represents an alkylene group or a phenylene group, R ₃ and R ₄ represent hydrogen,
Represents an alkyl group or an aryl group. however,
The alkyl group, aryl group, alkylene group, and phenylene group may contain an amine, or may have a substituent such as a halogen within a range that does not impair chargeability. ) Examples of such silicone oils include the following:

【table】

[Example 1]

Styrene-butyl methacrylate-dimethylaminoethyl methacrylate (weight ratio 7:2.5:
0.5) Mix 100 parts by weight of copolymer, 6 parts by weight of carbon black, and 3 parts by weight of polyethylene wax,
Melt and knead using a roll mill. After cooling, it is roughly pulverized using a hammer mill, and then finely pulverized using a jet pulverizer. Next, it was classified using an air classifier to obtain a non-magnetic black powder with a volume average particle size of approximately 13 μm. On the other hand, while stirring 100 parts by weight of silica fine powder synthesized by a dry method (specific surface area approximately 130 m ² /g), 12 parts by weight of silicone oil having an amine in the side chain (viscosity at 25°C, 70 cps, amine equivalent: 830) was added. The process was carried out for 60 minutes by spraying and maintaining the temperature at approximately 250°C. The amount of tribocharge of the generated treated silica is +
It was 130μc/g. A non-magnetic toner was prepared by adding 0.4 parts by weight of the above-mentioned fine silica powder treated with silicone oil having an amine in the side chain to 100 parts by weight of the black fine powder. The volume resistivity of this toner was 10 ¹⁵ Ωcm. In addition, styrene-methyl methacrylate-butyl maleic acid copolymer (weight ratio 8:1.5:0.5)
100 parts by weight, BET specific surface area by nitrogen adsorption method
Magnetic particles of 5.6 m ² /g consisting of 200 parts by weight of magnetite and 5 parts by weight of carbon black were prepared. The volume average diameter of these particles was 18μ. The toner and the magnetic particles were mixed at a weight ratio of 58:42 to prepare a developer. On the other hand, the Tg of the charge transport layer measured by DSC
A laminated OPC photoreceptor made of a methyl methacrylate-styrene (weight ratio 9:1) copolymer having a temperature of 80° C. or higher was fabricated on an aluminum conductive cylinder to obtain a photosensitive drum. The hardness of this photoreceptor was 21 g. At a linear surface speed of 66 mm/sec on this photosensitive drum -
It was uniformly charged by 6KV negative corona discharge, and then the original image was irradiated to form a latent image. This latent image is shown in Figure 1 with a sleeve diameter of 50 mm.
mm, sleeve surface magnetic flux density 850 Gauss, number of magnetic poles 12,
A sleeve-rotating magnet rotary type developer with a blade-sleeve gap of 0.6 mm is set with the distance between the photosensitive drum surface and the sleeve surface set to 0.5 mm, and a bias voltage of -250V is applied to the sleeve surface to generate developer formed on the sleeve. The layer was brought into contact with a photosensitive drum to develop the latent image to form a toner image, and then the toner image was transferred from the back side of the transfer paper while irradiating with -7 KV corona, and fixed with a heating roll. Meanwhile, the remaining toner on the drum was cleaned with a polyurethane blade. The pressure with which the blade was pressed against the photoreceptor was 15 g/cm. A clear image was obtained. A running test of 2,000 sheets was conducted under high temperature and high humidity conditions (32°C, 90%) while supplying non-magnetic toner, and good images with no image disturbance were obtained. [Example 2] The same procedure as in Example 1 was carried out except that a styrene-acrylonitrile copolymer having a Tg of 80°C or higher was used instead of the methyl methacrylate-styrene copolymer of Example 1. Good results were obtained. The hardness of this photoreceptor was 15 g. [Example 3] Instead of the silica fine powder of Example 1, silica fine powder synthesized by a dry method (specific surface area of approximately 200
m ² /g) of aminopropyltriethoxysilane 5
% and amino-modified silicone oil (viscosity
The procedure was substantially the same as in Example 1, except that fine silicic acid powder (tribocharge amount +160 μc/g) produced by treatment with 750 cps, 15% amine equivalent (1900 cps) was used. The results were equally good. The volume resistivity of the toner was 10 ¹⁵ Ωcm. [Example 4] The same procedure as in Example 1 was performed except that polymethyl methacrylate having a Tg of 80°C or higher was used instead of the methyl methacrylate-styrene copolymer in Example 1. Good results were obtained. The results were obtained. The hardness of this photoreceptor was 26 g. [Example 5] Magnetite with a BET specific surface area of 5.6 m ² /g was treated with 3 weight percent titanium coupling agent (TTS) and the BET specific surface area was 9.2 m ² /g.
Example 1 was carried out in the same manner as in Example 1 except that 150 parts by weight of magnetite was used, and a good image without image disturbance was obtained. [Example 6] 0.6% conductive tin oxide with a BET specific surface area of 55 m ² /g
Example 1 was carried out in substantially the same manner as in Example 1, except that a toner further added with was used, and good results were obtained. [Example 7] Good results were obtained in the same manner as in Example 1 except that polycarbonate with a Tg of 80°C or higher was used instead of the methyl methacrylate-styrene copolymer of Example 1. Obtained. The surface hardness of this photoreceptor was 32 g. [Example 8] Same as Example 1 except that 0.5 parts by weight of silica fine powder synthesized by a wet method and having a BET specific surface area of 92 m ² /g was added instead of the silica fine powder of Example 1. When almost the same procedure was carried out, good results with no image disturbance were obtained. [Example 9] Except that black powder was obtained using 100 parts by weight of styrene-butyl methacrylate (7:3) copolymer, 7 parts by weight of carbon black, 2 parts by weight of nigrosine, and 4 parts by weight of low molecular weight polypropylene. When the same procedure as in Example 1 was carried out, good results were obtained. [Example 10] The black powder of Example 9 and the magnetic particles of Example 1 were mixed at a weight ratio of 43:57 to prepare a developer. When this developer was used in almost the same manner as in Example 1, the image density was slightly low, but
A good image with almost no image disturbance was obtained. [Example 11] In place of the silica fine powder of Example 1, treated with 5 weight percent vinyltriethoxysilane.
Example 1 except that a silica fine powder synthesized by a wet method with a BET specific surface area of 85 m ² /g was used.
When the same procedure was carried out, good results were obtained. [Comparative example] Styrene-butyl methacrylate-dimethylaminoethyl methacrylate (weight ratio 7:2.5:
0.5) Using 100 parts by weight of copolymer, 6 parts by weight of carbon black, and 3 parts by weight of polyethylene wax, a non-magnetic toner (black powder) with a volume average particle diameter of about 13μ was prepared in the same manner as in Example 1. Prepared. In addition, instead of the sleeve-rotating magnet rotary type developer used in Example 1, a toner layer of the above non-magnetic toner with a thickness of 35 μm was formed on a stainless steel cylindrical sleeve with an outer diameter of 50 mm using an elastic blade. , the distance between the photosensitive drum surface and the sleeve surface.
0.25mm, keeping the toner layer on the sleeve out of contact with the photosensitive drum surface, and applying 400Hz to the sleeve.
The latent image on the photosensitive drum was developed while applying an AC bias of 1000V and a DC bias of -250V.
After the toner image formed by development was transferred to a transfer paper in the same manner as in Example 1, the surface of the photosensitive drum was cleaned with a polyurethane cleaning blade in the same manner as in Example 1. In the same manner as in Example 1, under a high temperature and high humidity environment (32
When running tests were conducted at 90% (°C, 90%), defective toner images began to form after about 1,000 sheets due to low-resistance substances adhering to the surface of the laminated OPO drum.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of an example of a developing device used in the present invention. 1... OPC photoreceptor, 2... Developer, 3... Sleeve, 4... Multipolar magnet, 5... Blade,
6...Developer layer.

Claims (1)

[Scope of Claims] 1. A charging step of negatively charging a laminated organic photoconductive photoconductor having a surface hardness of 12 to 100 g, and forming a latent image on the charged laminated organic photoconductive photoconductor by irradiating it with light. A latent image forming process to form a BET specific surface area of 2 to 20 on the developer support member.
m ² /g, magnetic particles with a volume average particle diameter of 8 to 50 μ containing a thermoplastic resin or thermosetting resin as a binder, and a magnetic particle containing a styrene copolymer as a binder resin. forming a layer of a developer containing a non-magnetic toner and a fine silica powder having a BET specific surface area of 0.5 to 500 m ² /g obtained by a nitrogen adsorption method and externally added to the non-magnetic toner; a developing step of forming a toner image of a non-magnetic toner by bringing the developer layer into contact with a laminated organic photoconductive photoreceptor that retains a latent image; An image forming method comprising: transferring a toner image of toner; and cleaning a layered organic photoconductive photoreceptor with a blade after the transfer. 2. The image forming method according to claim 1, wherein the cleaning blade is pressed against the surface of the laminated organic photoconductive photoconductor with a load of 1 to 100 g/cm. 3. The image forming method according to claim 1 or 2, wherein the magnetic particles have a volume average particle diameter that is three times or less the volume average particle diameter of the toner. 4. The image forming method according to any one of claims 1 to 3, wherein the silica fine powder has positive chargeability.