JPH09101627A - Image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming method applicable for a very small image forming device having excellent transfer property, capable of preventing wear in a photoreceptor and the like, capable of suppressing cometic phenomenone and filming and easy in cleaning. SOLUTION: This image forming method includes a process to form a latent image on a latent image holding body, a process to form a toner image on the latent image holding body by using a developer on a developer holding body, a process to transfer the toner image to a transfer body, and a process to remove and clean the toner remaining on the latent image holding body. The outer diameter of the latent image holding body 1 is 10-20mm, while the outer diameter of the developer holding body 3 is 5-15mm. The developer used is a magnetic one-component developer in which the volume average particle size D50 of toner particles is 4-9μm, the proportion of particles having <=3μm particle size is <=30% in number, and a metal oxide fine powder having 0.05-1.2μm average particle size is externally added by 0.1-8wt.%. A cleaning blade 6 is used in the cleaning process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming method such as an electrophotographic method, an electrostatic recording method and an electrostatic printing method.
More specifically, the present invention relates to an image forming method having at least charging, exposure, development, transfer and cleaning steps, and the cleaning step is a blade cleaning method.

[0002]

2. Description of the Related Art In recent years, the dry developing method in the electrostatic copying system has been used not only in conventional copying machines but also in the field of personal copying such as printers, facsimiles, and multi-function machines with copying machines. It is supposed to be used. For this reason, there is a strong demand for downsizing and weight reduction of the device itself, as well as ecological measures such as resource saving and recycling. In order to meet these demands, various improved image forming methods have been proposed, and research and development of new image forming methods have been studied. At present, the two-component developing method is the most widely used image forming method, but since only the toner in the developer is consumed and the toner concentration ratio is reduced, the toner and carrier are mixed. Toner must be replenished to keep the ratio constant. Therefore, there is a drawback that the developing device becomes large in size, and it is not possible to sufficiently meet the demands for downsizing and the like.
On the other hand, the one-component developing system is advantageous in reducing the size and weight of the apparatus because it does not have the above-mentioned drawbacks, but a technique capable of sufficiently meeting the recent demand for ultra-miniaturization has not been achieved.

Generally, in order to downsize the developing device, it is necessary to downsize the components of the device, and in particular, it is important to reduce the diameter and thickness of the latent image carrier and the developer carrier. However, reducing the diameter of the development carrier causes the curvature to increase, so that the toner charge imparting area becomes extremely narrow, which makes it difficult for the toner to be charged, and the charging rises slowly. . Further, when the diameters of the image bearing member and the developer bearing member are reduced, the developing area becomes narrower, which causes a problem that the image quality and the density are lowered.

In order to miniaturize the developing device, research has been conducted on miniaturizing not only the developing device but also the respective constituent devices. In particular, a cleaning blade system is adopted for the cleaning mechanism for downsizing. However, as the diameter and thickness of the latent image carrier are reduced, the latent image carrier and the cleaning blade are used more frequently as compared with the conventional developing device, which causes problems such as abrasion. Become. Furthermore, when the latent image bearing member is made thin, the strength of the latent image bearing member is weakened, so unless the pressure of the cleaning blade is reduced, the latent image bearing member is distorted and the pressure is partially increased. There is a problem that comet and filming locally occur. Further, lowering the pressure of the cleaning blade causes problems such as defective cleaning.

Japanese Unexamined Patent Publication No. 6-110324 discloses a developer carrying member having a diameter of 7 to 15 mm and 400 G or more, and 14 to
An image forming method has been proposed in which a latent image carrier of 29 mm is used and a toner whose residual magnetization, charge amount and particle size distribution are defined is used. This image forming method is certainly effective in achieving downsizing of the image forming apparatus, obtaining a sufficient image density, and obtaining a high-quality image without fog. However, in this method, the pressure of the cleaning blade is 1 to 5 g / cm, and the pressure is weak in the case of the small-diameter sleeve, resulting in poor cleaning.

Further, Japanese Patent Laid-Open No. 6-67452 discloses that
The distance between development and transfer and the distance between development and cleaning are short.
A technique is disclosed in which good transferability and cleaning properties are obtained by defining the charge amount. This method is effective in achieving downsizing and speeding up of the image forming apparatus, and obtaining good transferability and cleaning performance. However, even in this case, the pressure of the cleaning blade is high, so that the above-mentioned problem still remains.

Further, when a toner containing wax is used in order to prevent smudge and hot offset development, there is a problem that toner fusion occurs and the cleaning property deteriorates. Toners containing such polyolefins tend to have poor cleaning ability because of the large adhesive force between the toners or the large interaction with the layer forming member and the developer carrying member. Since the apparatus frequently uses the latent image carrier, toner fusion cannot be sufficiently prevented. Further, in these methods, the developer is sandwiched between the cleaning blade and the latent image carrier to lower the cleaning performance, and the development area is narrow, so that there is a problem in image quality maintenance.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems in the prior art. That is, it is an object of the present invention to provide an image forming method which is applied to a micro image device which is excellent in transferability, which prevents abrasion of a photoconductor and the like, and which is easy to clean and suppress comet and filming. .

Another object of the present invention is to provide an image forming method applied to a microminiature image device capable of preventing toner contamination on the surface of a photoreceptor and obtaining a stable and high quality image for a long period of time. It is in.

[0010]

Means for Solving the Problems As a result of intensive studies, the inventors of the present invention downsized the apparatus by using a developer carrier (developing roll) and a latent image carrier (photosensitive drum) having a specific diameter. By adding a metal oxide, particularly fluorine-containing cerium oxide fine particles, to specific toner particles,
It has been found that the above object can be achieved.

That is, in the image forming method of the present invention, the step of forming a latent image on the latent image carrier, and the step of forming a toner image on the latent image carrier using the developer on the developer carrier. ,
In an image forming method having a step of transferring the toner image onto a transfer body and a cleaning step of removing residual toner on the latent image carrier, the outer diameter of the latent image carrier is 10 to 20 mm.
And the outer diameter of the developer carrying member is 5 to 15 mm.
And the developer is a magnetic one-component developer,
The volume average particle diameter D _{50 of the} toner particles is 4 to 9 μm, the number of particles having a particle diameter of 3 μm or less is 30% or less, and the metal oxide fine powder has an average particle diameter of 0.05 to 1.2 μm. 0.1 to 8% by weight is externally added, and a cleaning blade is used in the cleaning step.

[0012]

Embodiments of the present invention will be described below in detail. The image forming method of the present invention comprises a latent image forming step of forming a latent image on a latent image carrier, a latent image on the latent image carrier using a developer formed in a thin layer on the developer carrier. Developing step, a transfer step of transferring the toner image on the latent image carrier to a transfer body, a fixing step of thermally fixing the toner image on the transfer body, and a cleaning step of removing the residual toner on the latent image carrier. have.

In the present invention, first of all, a method of uniformly charging by means of corona discharge is used to charge the latent image carrier, but a method of charging by using a charging roller to which a potential is applied may also be adopted. You can Further, in the step of forming a latent image on the latent image carrier, any known method may be used. The formed latent image is developed with toner particles, and the formed toner image is transferred onto the transfer body. For the transfer onto the transfer body, a method using a transfer corotron is generally adopted, but a transfer roller may be used. It is effective to employ a cleaning blade in the step of removing the residual toner on the latent image carrier.

A conventionally known method can be applied to the latent image forming step in the present invention, and an electrostatic latent image is formed on a latent image carrier such as a photosensitive layer or a dielectric layer by an electrophotographic method or an electrostatic recording method. Form an image. The cylindrical support used in the present invention can be obtained by a known production method such as extrusion-molding aluminum or aluminum alloy and then surface-treating, but in order to achieve a reduction in diameter, a metal strip or a metal plate is rolled. , Those having a cylindrical shape by welding the TIG joints are preferable in manufacturing. The joining portion welds the member to be welded by generating an arc between the tungsten electrode and the member to be welded. At this time, it is preferable that the shim is bitten immediately before the welding, and the welding is performed in an inert gas, for example, an argon gas with a constant gap maintained. The reason why the shims are bitten to keep a constant gap is to prevent the occurrence of beats due to welding, and the reason for welding in argon gas is to prevent the oxidation of metallic materials. Aluminum, stainless steel, nickel, copper, and the like are used as the material of the cylindrical support, but it is preferable to use stainless steel, brass, and the like in order to achieve thinning due to the reduction in diameter. In the present invention, the outer diameter (diameter) of the latent image carrier is
10 to 20 mm is used. The outer diameter is 10m
When it is less than m, the developing area is narrow and the developing time is short, so that the developability is remarkably lowered, and the transfer area is also narrowed, and the transferability and the cleaning ability are also lowered. If the outer diameter exceeds 20 mm, it becomes difficult to reduce the size.

A photosensitive layer having a charge generating material and a charge transporting material, or a charge generating layer and a charge transporting layer is formed on the cylindrical support. Between the cylindrical support and the photosensitive layer, if necessary, it has an adhesive function and a barrier function for preventing charge injection from the cylindrical support to the photosensitive layer at the time of retaining charges on the surface of the photosensitive body. An undercoat layer may be provided. The film thickness of the undercoat layer is 0.1 to 10 μm, and particularly, 0.
It is preferably 2 μm or less. Examples of the material for forming the undercoat layer include polyvinyl butyral, silane coupling agent, organic zirconium compound, polyvinyl pyridine, polyvinyl pyrrolidone, phenol resin, polyvinyl alcohol, poly-N-vinyl imidazole, polyethylene oxide, ethyl cellulose, ethylene-acrylic acid. Known compounds such as ester copolymer, casein, polyamide, polyvinyl chloride, polyvinyl acetate, vinyl chloride copolymer, glue and gelatin can be used.

When the photosensitive layer is a function-separated type in which the charge generation layer and the charge transport layer are function-separated, the charge generation layer is composed of a charge generation material. Examples of the charge generation material include phthalocyanine pigments such as metal phthalocyanine pigments and non-metal phthalocyanine pigments, azo dyes such as monoazo dyes and disazo dyes, perylene tetracarboxylic acid anhydrides, perylene pigments such as perylene tetracarboxylic acid imides, and indigo pigments. , Quinacridone pigments, polycyclic quinones such as anthraquinones, cyanine dyes, xanthene dyes, charge-transfer complexes composed of electron-donating substances such as poly-N-vinylcarbazole and electron-accepting substances such as trifluorenone, and pyrylium salt dyes And a eutectic complex composed of a polycarbonate resin.

The charge generating material may be dispersed in a suitable binder resin. As the binder resin, vinyl chloride-vinyl acetate copolymer, nylon resin, polyester resin, polycarbonate resin, polyacrylate resin, phenoxy resin, butyral resin, polystyrene resin, styrene-
Butadiene copolymer, polyvinyl acetal resin, diallyl phthalate resin, polysulfone resin, acrylic resin, vinyl acetate resin, polyphenylene oxide resin, alkyd resin, styrene-maleic anhydride copolymer, phenol resin, paraffin wax and the like can be used. . These may be used alone or in combination of two or more. When the charge generation layer is formed of only the charge generation material without using the binder resin, the strength is inferior, and therefore it is desirable to make the film thickness thicker than when the binder resin is used. The thickness of the charge generation layer is 0.1 to 20.
The range of μm is preferable, and the range of 0.1 to 0.3 μm is particularly preferable.

The charge transport layer is formed by binding the charge transport material with the above-mentioned binding resin. In the present invention, a substance capable of passing a sufficient amount of light to generate an electric charge when irradiated with light and capable of maintaining a desired charging potential when positively or negatively charged can be used. Examples thereof include a hydrazone derivative, a pyrazoline derivative, a styryl derivative, an ethylene derivative, an imidazolone derivative, an imidazolion derivative, a carbazole derivative, an oxazole derivative and a triphenylmethane derivative. A charge transport material made of a polymer compound such as a polyvinyl compound can also be used.

The thickness of the charge transport layer is preferably in the range of 5 to 100 μm, and the total thickness of the charge generation layer and the charge transport layer is preferably about 100 μm or less.
These layers are formed by mixing the above-mentioned constituent materials with an appropriate solvent and then applying the mixture. As the solvent, organic solvents such as alcohols, ketones, amides, esters, ethers and halogenated hydrocarbons can be used alone or in combination. As the coating method, for example, a dip coating method, a spray coating method, a spin coating method, a wire bar coating method, a blade coating method, a roller coating method, a curtain coating method or the like is used. A surface layer made of urethane resin, silicone resin, melamine resin, fluororesin, acrylic resin, butyral resin or the like can be provided on the photosensitive layer.

In the developing step, a thin layer of toner is formed by an elastic blade or the like on a rotating cylinder of a developer carrying member (developing roll) having a magnet inside, and the toner is conveyed to the developing section.
The developing roll and the latent image carrier that holds the electrostatic latent image are arranged at a constant interval in the developing section, and while applying a bias between the developing roll and the latent image carrier, Develop the latent image with toner. As the developer carrying member of the present invention, one obtained by drawing out a metal or ceramics such as aluminum, SUS, nickel or the like is used, but oxidation or metal plating on the surface of the substrate for controlling toner transportability and chargeability, You may perform surface treatments, such as grinding | polishing and a blast treatment, and coating with resin. In the present invention, the developer carrier having an outer diameter of 5 to 15 mm is used. If it exceeds 15 mm, it is difficult to achieve miniaturization of the image forming apparatus, and if it is less than 5 mm, it becomes difficult to manufacture the developer carrier itself, and at the same time, it is impossible to impart an appropriate electric charge to the developer. , It becomes difficult to obtain good image quality.

A blade cleaning method is used for the cleaning step in the image forming method of the present invention. As the cleaning blade, silicone rubber, urethane rubber, resin having elasticity, or the like can be used. The contact pressure between the latent image carrier and the cleaning blade tip is preferably in the range of 1 to 8 g / mm, more preferably 5 to 8 g / mm. When the contact pressure is less than 1 g / mm, the balance between the nip width and the pressure is poor, so that the cleaning property is significantly reduced and it becomes difficult to obtain a high quality image. The contact pressure is 8g / m
When it exceeds m, the contact pressure becomes strong, wear of the photosensitive member, comet and filming occur, and the image quality is disturbed.

The toner particles used in the present invention are required to have a volume average particle diameter D _{50 of 4 to} 9 μm.
In this case, it is easy to achieve good cleaning properties and developing properties. Further, in the ultra-small image forming apparatus, the size of the toner cartridge is limited, so it is necessary to reduce the toner consumption amount. From this viewpoint as well, the above particle size range is desirable. When the volume average particle diameter is less than 4 μm, the surface area per unit weight becomes large, and excessive charging causes fog, which makes it difficult to control the fog. In addition, cleaning with a cleaning blade method makes it difficult to scrape, and scratches and the like on the surface of the photoconductor are likely to occur. On the other hand, when the volume average particle diameter exceeds 9 μm, the surface area per unit weight becomes small, so that the charging becomes uneven and it becomes difficult to obtain a sufficient concentration.

The toner particles of the present invention have a particle size of 3 μm.
It is necessary to use particles having m or less of 30% by number or less, preferably 25% by number or less, and more preferably 20% by number or less. Conventionally, it has been considered that a small particle size toner has a problem of uneven density and fogging because it has poor transportability and is easily attached to a photoconductor, but as a result of studies by the present inventors, the particle size is 3 μm or less. The number of particles in 3
It was found that the above problem can be solved by setting the content to 0% or less. In addition, the particle size of the toner is TA-II, a particle size analyzer manufactured by Cole Counter, and an aperture size of 100
It is measured using μm.

As the binder resin for the toner particles, known synthetic resins and natural resins conventionally used can be used. Specifically, homopolymers or copolymers of one or more vinyl monomers can be used. Typical vinyl monomers include styrene, p-chlorostyrene, vinylnaphthalene, ethylenically unsaturated monoolefins such as ethylene, propylene, butylene and isobutylene, such as vinyl chloride, vinyl bromide, vinyl fluoride and acetic acid. Vinyl, vinyl propionate, vinyl benzoate, vinyl butyrate, vinyl formate, vinyl stearate,
Vinyl esters such as vinyl caproate, for example, methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, dodecyl acrylate, n-octyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, methyl- α-chloro acrylate,
Ethylenic monocarboxylic acids such as methyl methacrylate, ethyl methacrylate and butyl methacrylate, and their esters, for example, methylene type monocarboxylic acid substitution products such as acrylonitrile, methacrylonitrile and acrylamide, such as dimethyl maleate and diethyl maleate. ,
Ethylenic dicarboxylic acids such as dibutyl maleate and esters thereof, for example, vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and methyl isopropenyl ketone, for example vinyl ethers such as vinyl methyl ether, vinyl isobutyl ether, vinyl ethyl ether and the like. Examples thereof include vinylidene halides such as vinylidene chloride and vinylidene chloride, and N-vinyl compounds such as N-vinylpyrrole, N-vinylcarbazole, N-vinylindole and N-vinylpyrrolidone. Further, resins such as polyester may be used or used in combination.

In the present invention, metal oxide fine powder is added to the toner particles as an external additive. This metal oxide fine powder has the function of scraping off the deposits on the latent image carrier, and also weakens the image power of the small-diameter developer carrier and the small-diameter latent image carrier and the developer to improve the developability and transfer property. It has a function to improve sex. When a low-resistance metal oxide is used, the developer can be uniformly charged in a short time, and good developability and transferability can be seen. Examples of the metal oxide used in the present invention include, for example, strontium titanate, cerium oxide, magnetite, titanium oxide, zinc oxide, manganese dioxide and the like,
Among them, cerium oxide is more preferable, and fluorine-containing cerium oxide is particularly preferable. These fine particles may be treated with a silane coupling agent, a titanium coupling agent, silicone oil or other organic compound.

As the fluorine-containing cerium oxide, one obtained from a raw ore containing fluorine (bastnasite) can be used. In this case, fluorine is R--O.
It is contained in cerium oxide in the form of -F (R: rare earth atom). In addition, as the cerium oxide from a raw ore (monazite) that does not contain fluorine, one obtained by treating with a fluorine-containing surface treatment agent can be used. As what is used as this fluorine-containing surface treatment agent, trifluoropropyltrimethoxysilane, trifluoropropyltrichlorosilane, tridecafluorodecyltrichlorosilane, heptadecafluorodecyltrimethoxysilane, heptadecafluorodecylmethyldichlorosilane,
Examples thereof include fluoroalkylsilanes such as heptadecafluorodecylmethylmethoxysilane and fluorine-modified silicone oil. The fluorine content in the fluorine-containing cerium oxide is preferably in the range of 0.1 to 10% by weight. When the content of fluorine is large, the ability to scrape off the adhered substances is deteriorated, which causes a problem of cleaning failure, and the negative chargeability becomes too high, which makes it difficult to maintain the image density.

The metal oxide fine powder having a volume average particle diameter of 0.05 to 1.2 μm is used in an amount of 0.1 to 8 parts by weight based on 100 parts by weight of toner particles. It is necessary to include it. When a metal oxide having a volume average particle size of less than 0.05 μm is used, the cohesiveness is increased, and the toner may have poor charging or cleaning,
The ability to scrape deposits is reduced. Further, when a metal oxide having a thickness of 1.2 μm or more is used, the dissociation ability of aggregates of fine particles such as silica decreases, which causes a decrease in image density.

As the magnetic material of the toner particles, any known magnetic material that has been generally used in the past can be used. For example, metals such as iron, cobalt, nickel and alloys thereof, Fe ₃ O ₄ , γ-F
e ₂ O ₃ , metal oxide of cobalt-added iron oxide, MnZn
Ferrite, ferrite such as NiZn ferrite, magnetite, hematite and the like are used. These magnetic materials may be surface-treated with a coupling agent such as a silane coupling agent or a titanate coupling agent, inorganic fine particles such as silica or alumina, a fatty acid compound, or an organic compound such as a resin. The particle size is generally 0.05 to 0.
A range of 5 μm is appropriate. The shape of these magnetic materials is
Octahedrons, hexahedra and spheres are used. These magnetic powders are preferably contained in the toner particles in an amount of 30 to 70 parts by weight, more preferably 35 to 65 parts by weight.
It is in the range of parts by weight. If the amount of the magnetic powder is less than 30 parts by weight, the restraining force of the toner due to the magnetic force of the developer carrying member is lowered, causing a problem of toner scattering, and if it exceeds 70 parts by weight, the reproducibility of the image density is improved. There is a problem that

In the present invention, various substances can be added to the toner particles for the purpose of charge control and electric resistance control. Specifically, fluorinated surfactants, salicylic acid, iron dyes such as iron complexes, chromium dyes such as chromium complexes, polymeric acids such as copolymers containing maleic acid as a monomer component, quaternary Ammonium salts, azine dyes such as nigrosine, carbon black, etc.
It can be added in the range of 10 to 10 parts by weight. Furthermore, in order to improve the offset property, a release agent may be added. As the release agent, paraffins having 8 or more carbon atoms, polyolefins and the like are preferable, and examples thereof include paraffin wax, paraffin latex, microcrystalline wax and the like, polypropylene, polyethylene and the like, and these are used alone or in combination. . The addition amount is preferably in the range of 0.3 to 10 parts by weight. If the addition amount is less than 0.3 parts by weight, it does not sufficiently act as a release agent at the time of fixing, and if the addition amount exceeds 10 parts by weight, the mutual adhesive force between the toners or the layer forming member or the developer carrying member is not formed. However, there is a problem in the cleaning property due to the large interaction between the two.

Furthermore, in the toner particles, if necessary, for the purpose of improving durability, fluidity or cleaning property of the toner particles, inorganic fine powder such as silica and titania, fatty acid or its derivative and metal salt, etc. It is also possible to add the organic fine powder, a resin fine powder such as a fluorine resin, an acrylic resin, or a styrene resin. The fine particles preferably have an average primary particle diameter of 5 to 10 nm, and the inorganic fine powder may have a surface of the particles subjected to a hydrophobic treatment, and is used in the range of 1 to 3 parts by weight per 100 parts by weight of the toner. When the amount of external addition is less than 1 part by weight, the toner cannot be quickly and uniformly charged, and when the amount of external addition is more than 3 parts by weight, fine silica powder adheres to the photoconductor and comest or fill. It is easy to cause mingling. The toner used in the present invention can be manufactured by any known method, but those manufactured by a kneading and pulverizing method are particularly preferable. That is, a binder resin, a magnetic material, a release agent, a charge control agent and the like are melt-kneaded using a kneader such as a kneader or an extruder, cooled, pulverized and classified, and external additive fine powder is added and mixed. The method is preferred.

[0031]

Hereinafter, the present invention will be described with reference to examples.
The present invention is not limited by these. Example 1 Binder resin: Styrene-butyl acrylate copolymer 57 parts by weight (weight average molecular weight Mw = 150,000, copolymerization ratio 80:20) Magnetic substance: magnetite (hexahedral, particle size: 0.15 μm, BET: 7 m ³ / g) 40 parts by weight Charge control agent: (Cr-containing dye) 1 part by weight Release agent: Polypropylene wax 2 parts by weight After mixing the above materials with a Henschel mixer, set the temperature at an extruder at 150 ° C., screw rotation Number 30
Melt kneading was performed at 0 rpm and a supply speed of 250 kg / h. After cooling, coarse pulverization was performed, followed by fine pulverization using a jet mill, and the pulverized product was air-classified to obtain a toner classified product having a volume average particle diameter D ₅₀ of 6.8 μm and 3 μm or less of 24 number%. . 100 parts by weight of the obtained toner classification product was treated with silicone oil-treated silica (average particle diameter 12 nm).
1.0 part by weight and 1.0 part by weight of fluorine-containing cerium oxide (volume average particle size: 0.6 μm, fluorine content: 1.0% by weight) were stirred with a 75-liter Henschel mixer at a stirring speed of 30 m / s for 20 minutes. The toner was added and mixed to obtain a toner.

The toner thus obtained was subjected to a print test on about 30,000 sheets under high temperature and high humidity and low temperature and low humidity using the image forming apparatus shown in FIG. Here, as the latent image carrier 1, a cylindrical organic photoreceptor having a stainless steel (SUS) substrate and an outer diameter of 15 mm produced by TIG welding is used. The cleaning blade 6 made of silicone rubber is a latent image carrier. The tip was brought into contact with No. 1 at a pressure of 7.0 g / mm. As the developer carrying member 3, an aluminum developer carrying member having an outer diameter of 10 mm and containing a 700 G quadrupole magnet is used, and a silicone rubber layer forming blade 4 is used.
Was brought into contact with the developer bearing member at a linear pressure of 30 g / mm to form a thin layer of toner. The latent image carrier and the developer carrier were arranged so as to have a distance of 400 μm. The latent image carrier 1 is charged to −350 V by using the charging roller 2 and then exposed to a laser beam to form an electrostatic latent image,
Frequency of 2.0 kHz, Vpp 1.2 kV on developer carrier
And the DC voltage of -250 V were superposed on each other to develop the electrostatic latent image. The peripheral speed of the latent image carrier is 60 mm / s, and the peripheral speed of the developer carrier is 120 mm / s.
The transfer roller 5 was used to transfer the toner.

Example 2 Binder resin: Polyester (bisphenol A type polyester) 55 parts by weight (weight average molecular weight Mw = 50,000) Magnetic substance: Magnetite 40 parts by weight (hexahedral, particle size: 0.15 μm, BET: 7 m) ³ / g) Charge control agent: TRH (Cr-containing dye) 1 part by weight Release agent: Polypropylene wax 4 parts by weight After mixing the above materials with a Henschel mixer, the temperature is set to 150 ° C with an extruder and the screw rotation speed is 30
Melt kneading was performed at 0 rpm and a supply speed of 200 kg / h. After cooling, coarse pulverization was performed, then fine pulverization was performed using a jet mill, and the pulverized product was classified by wind force to obtain a volume average particle diameter D.
A toner classified product was obtained in which ₅₀ was 7.4 μm and 3 or less was 27% by number. 100 parts by weight of the obtained toner classification product was treated with silicone oil-treated silica (average particle diameter 12 nm).
1.8 parts by weight and 3.0 parts by weight of fluorine-containing cerium oxide (volume average particle size: 1.1 μm, fluorine content: 1.0% by weight) were added to a 75 liter Henschel mixer at a stirring speed of 30 m / s for 20 minutes. The toner was added and mixed to obtain a toner. With respect to the obtained toner, the same image forming apparatus as in Example 1 was used, except that the silicone rubber cleaning blade 6 was brought into contact with the latent image carrier 1 at a pressure of 8.0 g / mm. Print test.

Example 3 The same toner pulverized product as in Example 1 was classified to obtain a toner classified product having a volume average particle diameter D ₅₀ of 6.4 μm and 3 μm or less of 18 number%. To 100 parts by weight of the obtained toner classified product, 1.5 parts by weight of silicone oil-treated silica and 1.0 part by weight of magnetite (volume average particle size of 0.25 μm) were stirred with a 75 liter Henschel mixer at a stirring speed of 30 m. External mixing was carried out for 20 minutes at a speed of 1 / s to obtain a toner. With respect to the obtained toner, the same image forming apparatus as in Example 1 was used, except that the cleaning blade 6 made of silicone rubber was brought into contact with the latent image carrier 1 at the tip with a pressure of 6.0 g / mm. Print test.

Example 4 The same toner pulverized product as in Example 1 was classified to obtain a toner classified product having a volume average particle diameter D ₅₀ of 7.2 μm and 3 μm or less of 14 number%. To 100 parts by weight of the obtained toner classified product, 1.5 parts by weight of silicone oil-treated silica and 1.0 part by weight of titanium oxide (volume average particle diameter 0.3 μm) were added.
Mixing speed 30 with a 5 liter Henschel mixer
External addition and mixing were performed at m / s for 20 minutes to obtain a toner. With respect to the obtained toner, the same image forming apparatus as in Example 1 was used, except that a silicone rubber cleaning blade 6 was brought into contact with the latent image carrier 1 at a pressure of 5.5 g / mm. Print test.

Example 5 The same toner pulverized product as in Example 1 was classified to obtain a classified product having a volume average particle diameter D ₅₀ of 6.8 μm and 3 μm or less of 24% by number. To 100 parts by weight of the obtained toner classified product, 1.5 parts by weight of silicone oil-treated silica and 1.0 part by weight of zinc oxide (volume average particle size 0.2 μm) were stirred with a 75 liter Henschel mixer. 30 m / s
External mixing was carried out for 20 minutes to obtain a toner. About the obtained toner, a cleaning blade 6 made of silicone rubber
Using the same image forming apparatus as in Example 1 except that the tip is brought into contact with the latent image carrier 1 at a pressure of 7.0 g / mm.
The same print test was performed.

Example 6 The same toner pulverized product as in Example 2 was classified to obtain a toner classified product having a volume average particle diameter D ₅₀ of 7.4 μm and 3 μm or less of 28 number%. To 100 parts by weight of the obtained toner classified product, 1.5 parts by weight of silicone oil-treated silica and 1.0 part by weight of titanium oxide (volume average particle diameter 0.3 μm) were added.
Mixing speed 30 with a 5 liter Henschel mixer
External addition and mixing were performed for 20 minutes at m / s to obtain a toner. With respect to the obtained toner, the same image forming apparatus as in Example 1 was used, except that the cleaning blade 6 made of silicone rubber was brought into contact with the latent image carrier 1 at the tip with a pressure of 6.0 g / mm. Print test.

Comparative Example 1 The same toner pulverized product as in Example 1 was classified to obtain a toner classified product having a volume average particle diameter D ₅₀ of 6.9 μm and 3 μm or less of 34% by number. To 100 parts by weight of the obtained toner classified product, 1.0 part by weight of silicone oil-treated silica is added to 75 parts by weight.
Mixing speed 30m with liter Henschel mixer
/ S was externally added and mixed for 20 minutes to obtain a toner. For the obtained toner, using the same image forming apparatus as in Example 1,
The same print test was performed.

Comparative Example 2 The same toner pulverized product as in Example 3 was classified to obtain a toner classified product having a volume average particle diameter D ₅₀ of 6.5 μm and 3 μm or less of 38% by number. To 100 parts by weight of the obtained toner classified product, 1.5 parts by weight of silica treated with silicone oil is added to 75 parts by weight.
Mixing speed 30m / with a liter Henschel mixer
External mixing was performed for 20 minutes at s to obtain a toner. A similar print test was performed on the obtained toner by using the same image forming apparatus as in Example 1.

The toners obtained in Examples 1 to 6 and Comparative Examples 1 and 2 were used in the image forming apparatus shown in FIG. 1 to perform a print test on about 30,000 sheets under high temperature and high humidity and low temperature and low humidity. Then, the adhesion and abrasion of the photoreceptor, the transferability, the cleaning property, the image density, and the comprehensive evaluation of the image quality (density unevenness, fog, black streaks) were observed. Table 1 shows the test results.

[0041]

[Table 1] In Table 1, the respective evaluation criteria are as follows.

Adhesion and Wear of Photoreceptor ◯: Good, Δ: Practically no problem level, ×: Problem cleaning property ○: Good, Δ: Practical problem level, ×: Problem image quality O: Good, Δ : No problem in practical use, ×: There is a problem Transfer efficiency is 10 toner amount developed on the latent image carrier.
The amount of toner transferred onto the transfer body is shown as 0. Also,
The image density is a density measuring device X-Rit manufactured by X-Rite.
It is a value measured by e404A.

[0043]

As described above, the image forming method of the present invention uses a latent image carrier having a small diameter and a developer carrier having a small diameter, and adds a metal oxide to toner particles having a specific particle size distribution. Thus, even when applied to an ultra-small image forming apparatus, it is possible to obtain a high-quality image with excellent transferability, and without abrading the surface of the latent image carrier and the cleaning blade, Comet and filming can be suppressed, and cleaning can be easily performed.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an image forming apparatus used in an embodiment of the present invention.

[Explanation of symbols]

1 ... Latent image carrier, 2 ... Charging roller, 3 ... Developer carrier, 4 ... Layer forming blade, 5 ... Transfer roller, 6 ... Cleaning blade.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical display location G03G 21/00 318 (72) Inventor Toyofumi Inoue 1600 Takematsu, Minamiashigara-shi, Kanagawa Fuji Xerox Co., Ltd. (72) Inventor Hirono 1600 Takematsu, Minamiashigara City, Kanagawa Prefecture, Fuji Xerox Co., Ltd. (72) Inventor Satoshi Torigoe, 1600 Takematsu, Minamiashigara City, Kanagawa Prefecture, Fuji Xerox Co., Ltd. (72) Inventor, Hiroe Okuyama, Kanagawa Prefecture 1600 Takematsu, Minamiashigara City, Fuji Xerox Co., Ltd. (72) Inventor Takatoshi Fujii 1600 Takematsu, Minami Ashigara City, Kanagawa Prefecture, Fuji Xerox Co., Ltd.

Claims (1)

[Claims] 1. A step of forming a latent image on a latent image carrier, a step of forming a toner image on the latent image carrier using a developer on the developer carrier, and a step of forming the toner image on a transfer body. In the image forming method, the latent image carrier has an outer diameter in the range of 10 to 20 mm, and the developer carrier has an outer diameter. Is in the range of 5 to 15 mm, the developer is a magnetic one-component developer, the volume average particle diameter D _{50 of the} toner particles is 4 to 9 μm, and the number of particles having a particle diameter of 3 μm or less is 30% by number or less. And the average particle size is 0.05 to 1.2.
An image forming method, characterized in that 0.1 to 8% by weight of a metal oxide fine powder is externally added, and a cleaning blade is used in the cleaning step.