JP2002207304A - Image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an image forming method by which the wear amount of the photoreceptor surface due to friction by a carrier deposited is decreased even when a toner and a carrier with smaller particle sizes are used and by which images are free from scratches or decrease in the density even for long- term use. SOLUTION: The image forming method is carried out by incorporating silicone oil into the surface layer of the photoreceptor, by forming an electrostatic latent image on the photoreceptor by using electrifying and exposing means and then by developing the image by using a two-component developer consisting of a nonmagnetic toner and a magnetic carrier. When the weight average particle size of the toner and the weight average particle size of the carrier are 5 to 10 μm and 15 to 45 μm, respectively, the frictional coefficient A of the surface of the photoreceptor and the dynamic frictional coefficient B of the magnetic brush are controlled to satisfy the relation of A/2+B<=0.55.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electrophotographic photosensitive member and an image forming method using a two-component developer.

[0002]

2. Description of the Related Art In an electrophotographic method, an electrostatic latent image is formed on the surface of a photoreceptor using a charging and exposing means, and then the electrostatic latent image is developed with a developer to obtain a toner image. Is transferred to a transfer member and then fixed to obtain a visible image. As a method of developing an electrostatic latent image, a powder cloud method,
A cascade method, a magnetic brush method, and the like can be given, but the magnetic brush method is usually used.

The two-component dry developer used in the magnetic brush method is such that toner particles made of a resin, a colorant, and the like are held on a magnetic carrier made of a ferrite powder or the like by an electric force generated by friction between the two particles. When the electrostatic latent image comes close to the electrostatic latent image, the attraction of the toner particles in the latent image direction by the electric field formed by the electrostatic latent image overcomes the bonding force between the toner particles and the carrier particles, and the toner particles become electrostatic latent images. The electrostatic latent image is visualized by being attracted and attached to the image. The developer is used repeatedly while replenishing the toner consumed by the development.

As devices using such an electrophotographic method, not only copying machines which have been widely used until now, but also laser beam printers have been widely used as output devices due to the spread of computers in recent years. As a result, the demand for higher image quality is gradually increasing.

[0005] In order to achieve such a high image quality, the first means considered from the developer side is to reduce the particle size of the toner and the carrier. When the toner particle size is reduced, it is necessary to increase the toner concentration and at the same time, reduce the carrier particle size in order to ensure toner developability.
The reduction in the particle size of the carrier can be expected to improve gradation and solid uniformity because the above-described magnetic brush can be formed densely, and is also advantageous in terms of preventing deterioration of the developer because the carrier itself is reduced in weight. It is.

However, when the particle size of the carrier is reduced as described above, a problem of carrier adhesion occurs. Normally, the carrier is held on the developing sleeve by a magnetic force, but at the same time, charge is generated in the carrier by electrostatic induction or charge injection, and an electrostatic force acts between the charge on the photoreceptor. As the particle size of the carrier becomes smaller, the magnetic force acting on each particle becomes weaker, so that the electrostatic force with the photoconductor overcomes the holding force of the sleeve, and the carrier tends to adhere to the photoconductor. Especially, the carrier particle size is 80μ.
When it is smaller than m, the carrier tends to adhere to the background and the photoreceptor tends to be worn and scratched. The carrier thus attached is transferred to the transfer medium together with the toner image, and thus appears as dust on the background on the image.

As a method for solving such a problem, some improvement measures focusing on the surface properties of the photoreceptor have been proposed. For example, Japanese Patent Application Laid-Open No. 9-152775 describes a proposal in which, when a magnetic carrier having a volume average particle diameter of 20 to 80 μm is used, inorganic particles are contained in the outermost surface layer of the photoreceptor and the ten-point average roughness is specified. Have been. However, in this method, the effect is still insufficient to use a carrier with a smaller particle size, and since there is a difficulty in the production method because a coating film in which inorganic particles are dispersed is required, a simpler method is used. It is desired to establish an image forming method capable of obtaining excellent image quality.

Japanese Patent No. 2925605 discloses that a peripheral speed ratio of a magnet sleeve to a photoreceptor drum is fixed within a certain range according to an average particle diameter of a magnetic carrier used for a two-component developer, a saturation magnetization and a dynamic friction coefficient of a magnetic brush. It is described that an image having a high image density and a good resolution can be obtained by performing the development while setting the value within the range. However, in this method, the effect is still insufficient to use a toner and a carrier having a small particle size, and since the toner has a small particle size, the specific surface area per unit volume increases, and the charge amount of the toner increases. When printing is performed, the amount of charge increases, and a problem arises in that carrier adhesion to a non-image portion due to counter charge occurs. Furthermore, this has tended to increase the abrasion and damage of the photoreceptor due to carrier adhesion to the background.

[0009]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention reduces wear on the surface of a photoreceptor due to adhesion of a carrier or friction of a magnetic brush or the like even when a toner and a carrier having a smaller particle size are used. It is an object of the present invention to provide an image forming method in which the amount is reduced, the carrier is prevented from adhering, and the image is free from scratches and density reduction even in long-term use.

[0010]

As a result of various studies on the above problems, the present inventors have found that the surface friction coefficient of a photoreceptor containing a silicone oil in the surface layer and the use of a non-magnetic toner having a small particle size and a magnetic carrier are reduced. By defining the coefficient of dynamic friction coefficient of the magnetic brush when used, it is possible to achieve high-definition image quality while preventing the photoreceptor surface from being abraded, and also to define the saturation magnetization range of the carrier, silica and titanium oxide. It has been found that by containing a predetermined amount of, it is possible to prevent the carrier from adhering at the initial stage and at the time of the run, and to provide an excellent image free from background stain. Furthermore, it has been found that even better results can be obtained by adding an external additive treated with silicone oil as a means for reducing the friction on the surface of the photoreceptor, leading to the present invention. That is, according to the present invention, first, the surface layer of the electrophotographic photoreceptor contains silicone oil, and the electrostatic latent image formed on the photoreceptor using the charging and exposing means is formed by a non-magnetic toner and In an image forming method for performing development using a two-component developer comprising a magnetic carrier, the toner has a weight average particle diameter of 5 to 10 μm,
When the weight average particle diameter of the carrier is 15 to 45 μm, and the surface friction coefficient of the electrophotographic photoreceptor is A and the dynamic friction coefficient of the magnetic brush is B, the following relationship is established. A method of forming is provided.

A / 2 + B ≦ 0.55

Second, in the image forming method according to the first aspect, the saturation magnetization of the magnetic carrier is 50 to 90 e.
mu / g is provided.

Third, in the image forming method according to the first or second aspect, the additive externally added to the toner may be:
An image forming method comprising silica fine particles and titanium oxide fine particles is provided.

Fourth, in the image forming method according to the third aspect, the addition ratio of the silica fine particles and the titanium oxide fine particles is titanium oxide fine particles / silica fine particles <0.6. An image forming method as described above is provided.

Fifth, there is provided an image forming method according to the third or fourth aspect, wherein the fine silica particles are treated with a treating agent containing silicone oil.

Sixth, there is provided an image forming method according to the first aspect, wherein the viscosity of the silicone oil contained in the surface layer of the electrophotographic photosensitive member is 100 cs or less. Is done.

[0017]

Embodiments of the present invention will be described below. As the non-magnetic toner in the present invention, toners manufactured using a conventionally known method can be widely used. Specifically, a mixture comprising a binder resin, a colorant, and a polarity control agent is melt-kneaded in a hot roll mill, then cooled and solidified, and pulverized and classified. In addition, optional additives are added as needed. The toner that can be used in the present invention has a weight average particle diameter of 5-1.
Although it is in the range of 0 μm, the weight average particle size of the toner can be measured by various methods. A specific example of the present invention is a method using a Coulter counter.

As a Coulter counter which can be used for the above-mentioned measurement, there can be specifically mentioned a Coulter counter type II (manufactured by Coulter Inc.). The obtained results are, for example, a number distribution and a volume distribution. The characteristics are analyzed. The electrolyte used at this time is 1
A 1% aqueous solution of sodium chloride adjusted with graded sodium chloride can be used. A specific measurement example will be described later.

As the binder resin, all of those conventionally used as binder resins for toner are applied. Specifically, polystyrene, polychlorostyrene,
Styrene such as polyvinyltoluene and its substituted homopolymer; styrene / p-chlorostyrene copolymer, styrene / propylene copolymer, styrene / vinyltoluene copolymer, styrene / vinylnaphthalene copolymer, styrene / acryl 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, styrene / butadiene copolymer, styrene / isoprene copolymer, styrene / acrylonitrile / indene copolymer, styrene / Styrene copolymers such as maleic acid copolymer and styrene / maleic acid ester copolymer; polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, polyvinyl butyl butyral, polyacryl Acid resin, rosin, modified rosin, terpene resin, phenol resin, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, chlorinated paraffin,
Examples thereof include paraffin waxes, which are used alone or in combination of two or more.

As the colorant, any known colorants can be used. As a black colorant,
For example, carbon black, aniline black, furnace black, lamp black and the like can be used. Examples of cyan colorants include phthalocyanine blue, methyllen blue, Victoria blue, methyl violet,
Aniline blue, ultramarine blue and the like can be used. Examples of magenta colorants include Rhodamine 6G
Rake, dimethyl quinacridone, watching red,
Rose bengal, rhodamine B, alizarin lake and the like can be used. As a yellow colorant, for example, chrome yellow, benzidine yellow, hansa yellow, naphthol yellow, molybdenum orange, quinoline yellow, tartrazine and the like can be used.

Further, these toners may contain a small amount of a charge-imparting agent, for example, a dye / pigment, a polarity controlling agent, etc., in order to give more efficient charge-impartment. Examples of the polarity controlling agent include metal complexes of monoazo dyes, nitrohumic acid and salts thereof, salicylic acid, naphthoic acid, metal complexes of dicarboxylic acid such as Co, Cr and Fe, organic dyes,
And quaternary ammonium salts.

Further, the present invention is characterized in that it contains silica fine particles and titanium oxide fine particles treated with a silicone oil treating agent as an additive for a toner. It is preferable to use one or more of modified silicone oil, hydrogen silicone oil or fluorine-containing silicone oil having a reactive group therein, but use an unmodified silicone oil having no such active group in the molecule. It is also possible. Examples of the modified silicone oil having a reactive group in the molecule include a modified silicone oil containing at least one group selected from the group consisting of a hydroxy group, a carboxyl group, an amino group, an epoxy group, an ether group and a mercapto group in the molecule. More than species are preferred. The viscosity of the silicone oil is preferably 5 to 15,000 cp at room temperature. When silica fine particles treated with a silicone oil treating agent are used, abrasion of the photosensitive drum by the silica fine particles is reduced.

The surface area of the titanium oxide fine particles to be used is 30 m in specific surface area by nitrogen adsorption by the BET method.
Good results are obtained when the ratio is at least ² / g, particularly 50 to 400 m ² / g. Excessive charging due to rubbing is likely to occur due to the small particle size of the toner, but by controlling the charging and incorporating titanium oxide fine particles that can impart fluidity, the charging when printing continuously is performed. It is possible to suppress the increase in the amount and prevent the carrier from adhering to the non-image portion due to the counter charge. However, when the titanium oxide fine particles are added in a larger amount than the silica fine particles, the charge amount decreases over time during printing. For this reason, it can be prevented by adding the titanium oxide fine particles / silica fine particles in an addition ratio of 0.6 or less. The total amount of the fine powder is preferably 0.5 to 2% by weight based on the toner.

As the magnetic carrier used in the present invention, those obtained by providing a coating layer on magnetic core particles as necessary are widely used. As the core particles, conventionally known magnetic materials are used, and examples thereof include ferromagnetic metals such as iron, cobalt, and nickel, and alloys and compounds such as magnetite, hematite, and ferrite.

Incidentally, the magnetic properties of the carrier are influenced by the magnet roller built in the developing sleeve, and greatly affect the developing properties and transportability of the developer. The carrier has a saturation magnetization of 50 to 9
At 0 emu / g, in color copying, the image uniformity and gradation reproducibility are excellent and suitable. 90 em saturation magnetization
If it exceeds u / g (with respect to the applied magnetic field of 3000 Oersted), the brush-like spikes formed of the carrier and the toner on the developing sleeve facing the electrostatic latent image on the photoconductor during development become hard. It is in a tight state, and the gradation and the reproduction of halftone are deteriorated. On the other hand, if it is less than 50 emu / g, it becomes difficult to hold the toner and the carrier on the developing sleeve satisfactorily, and the problem that the adhesion of the carrier and the scattering of the toner are deteriorated is likely to occur.

Further, if the residual magnetization and coercive force of the carrier are too high, good transportability of the developer in the developing device is hindered,
As an image defect, blurring or uneven density in a solid image is likely to occur, and the developing ability is reduced. Therefore, in order to maintain the developability, the remanent magnetization is 10 emu / g or less, preferably 5 emu / g or less, more preferably substantially 0, and the coercive force is 40 Oe or less (3000 Oe, the applied magnetic field). On the other hand, it is important that it is preferably 30 Oe or less, more preferably 10 Oe or less. In consideration of these, it is preferable to use ferrite as the core material.

As the resin used for the coating layer,
Polyolefin resins, for example, polyethylene, polypropylene, chlorinated polyethylene and chlorosulfonated polyethylene; polyvinyl and polyvinylidene-based resins, for example, polystyrene, acrylic resin (for example, polymethyl methacrylate), polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral,
Polyvinyl chloride, polyvinyl carbazole, polyvinyl ether and polyvinyl ketone; vinyl chloride / vinyl acetate copolymer; styrene / acrylic acid copolymer; silicone resin such as straight silicone resin comprising organosiloxane bond or a modified product thereof (eg, alkyd) resin,
(Modified products of polyester, epoxy resin, polyurethane, etc.); fluorine resins such as polytetrafluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, polychlorotrifluoroethylene; polyamides; polyesters such as polyethylene terephthalate; polyurethane; polycarbonate; Resins, for example, urea-formaldehyde resin; epoxy resin and the like. Among these resins, preferred in terms of preventing toner spent,
An acrylic resin, a silicone resin or a modified product thereof and a fluorine resin are used, and a silicone resin or a modified product thereof is particularly preferable. As a method for forming the coating layer, a resin may be applied to the surface of the carrier core particles by a method such as a spraying method or an immersion method as in the related art.

Further, a fine powder can be added to the coating layer for the purpose of adjusting the resistance of the carrier and the like. The fine powder dispersed in the coating layer preferably has a particle size of about 0.01 to 5.0 μm. The fine powder is preferably added in an amount of 2 to 30 parts by weight based on 100 parts by weight of the coating resin,
Particularly, 5 to 20 parts by weight is preferable. As the fine powder, conventionally known fine powders are used, and examples thereof include metal oxides such as silica, alumina and titania, and pigments such as carbon black.

In the present invention, the weight average particle diameter of the carrier is 15 to 45 μm. However, when the particle diameter of the carrier and the toner is reduced, the adverse effect that occurs is that the fluidity of the developer is reduced. Is difficult to circulate. As a countermeasure for this, there is a change in apparatus conditions such as increasing the stirring intensity in the developing device, but this is not preferable because it causes a problem such as shortening the durability life of the developer. Therefore, it is important to ensure a certain level of fluidity as a developer. The fluidity of the developer is 25 to 5
It is preferably 5 (seconds / 50 g).

Next, the electrophotographic photosensitive member used in the present invention will be described. In the present invention, a widely known electrophotographic photoreceptor having a photosensitive layer provided on a conductive substrate can be used, but an organic photoreceptor having advantages such as low cost, productivity, and no pollution is used. In particular, a function-separated type photoconductor using a combination of a charge generating substance and a charge transfer substance is most preferably used in terms of performance.

The drum-shaped conductive support which can be used in the present invention includes Al, Ni, Fe, Cu,
A metal or alloy such as Au; a metal film such as Al, Ag, Au, etc. on an insulating substrate such as plastic or glass such as polyester, polycarbonate, polyimide or the like;
An example in which a metal oxide film such as ₂ O ₃ or SnO ₂ is provided can be given.

The function-separated type photoreceptor is formed by laminating a charge generation layer and a charge transport layer on these conductive supports. The charge generation layer may be formed only of the charge generation substance, or may be formed by uniformly dispersing the charge generation substance in a binder. The charge generation layer is formed by dispersing these components in a suitable solvent, applying the resultant on a conductive support, and drying.

As the charge generating material, for example, C.I. Pigment Blue 25 (color index (CI211)
80), C.I. Pigment Red 52 (CI4510)
0), CI Basic Red 3 (CI45210)
And the like, phthalocyanine pigments having a porphyrin skeleton, azo pigments having a carbazole skeleton (JP-A-53
95033), azo pigments having a stilbene skeleton (described in JP-A-53-138229), azo pigments having a distyrylbenzene skeleton (described in JP-A-53-133)
No. 455), azo pigments having a triphenylamine skeleton (described in JP-A-53-132547), azo pigments having a dibenzothiophene skeleton (described in JP-A-54-21)
728), an azo pigment having an oxadiazole skeleton (described in JP-A-54-12742), an azo pigment having a fluorenone skeleton (described in JP-A-54-22834), an azo pigment having a bisstilbene skeleton Pigments (described in JP-A-54-17733), azo pigments having a distyryloxadiazole skeleton (described in JP-A-54-2129), and azo pigments having a distyrylcarbazole skeleton (described in JP-A-54-17732) And a trisazo pigment having a carbazole skeleton (JP-A-57-195767).
Phthalocyanine pigments such as C.I. Pigment Blue 16 (CI74100), C.I.
73410) and other indigo pigments, Argo Scar Red B
(Violet) Indance Scarlet R
Organic pigments such as perylene-based pigments (manufactured by Bayer AG) and square-color pigments: Inorganic pigments such as Se, Se alloys, CdS, and amorphous Si can be used.

As the binder resin, polyamide, polyurethane, polyester, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, poly-N-vinyl carbazole, polyacrylamide and the like are used. Can be The amount of the binder resin is 5 to 100 parts by weight of the charge generating substance.
100 parts by weight, preferably 10 to 50 parts by weight, is suitable.

The solvent used here is tetrahydrofuran, cyclohexanone, dioxane, dichloroethane, cyclohexane, methyl ethyl ketone, 1,1,1
A single solvent or a mixed solvent such as 2-trichloroethane, 1,1,2,2-tetrachloroethane, dichloromethane, and ethyl cellosolve is preferred.

The average thickness of the charge generation layer is 0.01 to 2 μm.
m, preferably 0.1 to 1 μm.

The charge transporting layer is formed by dissolving a charge transporting substance, a binder resin, and if necessary, a plasticizer and a leveling agent in a suitable solvent, applying the solution on the charge generating layer and drying.

Examples of the charge transport material include poly-N-vinylcarbazole and its derivatives, poly-γ-carbazolylethylglutamate and its derivatives, pyrene-formaldehyde condensate and its derivatives, polyvinylpyrene,
Polyvinyl phenanthrene, oxazole derivative, imidazole derivative, triphenylamine derivative, 9- (p
-Diethylaminostyryl) electron donating substances such as anthracene, 1,1-bis (4-dibenzylaminophenyl) propane, styrylanthracene, styrylpyrazoline, phenylhydrazones, and α-phenylstilbene derivatives.

As the binder resin, polystyrene,
Styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer,
Polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyvinyl chloride, polyvinylidene chloride, polyacrylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl Thermoplastic or thermosetting resins such as toluene, poly-N-vinylcarbazole, acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, phenol resin, and alkyd resin.

As the binder resin, polystyrene,
Styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer,
Polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyvinyl chloride, polyvinylidene chloride, polyacrylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl Thermoplastic or thermosetting resins such as toluene, poly-N-vinylcarbazole, acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, phenol resin, and alkyd resin.

Solvents for forming the charge transport layer include tetrahydrofuran, dioxane, toluene, monochlorobenzene, 1,2-dichloroethane, cyclohexanone, dichloromethane, 1,1,2-trichloroethane, 1,1,2,2- Tetrachloroethane and a mixed solvent thereof are preferred.

The thickness of the charge transport layer is 10 to 100 μm, preferably 20 to 40 μm.

In the present invention, an intermediate layer may be provided between the conductive support and the charge generation layer, if necessary, in order to improve the adhesion and the charge blocking property. Further, it may have a reverse layer structure in which a charge transport layer and a charge generation layer are laminated on a conductive substrate in this order, and the outermost surface layer is a protective layer provided for the purpose of improving abrasion resistance and the like. Is also good.

In the present invention, the surface friction coefficient A of the electrophotographic photosensitive member and the dynamic friction coefficient
By using a combination of the two so that the relationship of A / 2 + B ≦ 0.55 is satisfied, it is possible to prevent abrasion of the film on the surface of the photosensitive member while achieving high-definition image quality, and obtain a high-definition image. be able to. That is, when the dynamic friction coefficient B of the magnetic brush is 0.40, the surface friction coefficient A of the photoconductor is 0.30 or less, and the dynamic friction coefficient of the magnetic brush is 0.10.
When 46 is used, it may be 0.18 or less.

The dynamic friction coefficient μ of the magnetic brush is described in
It is calculated according to the measuring method described in JP-A-147937. A torque meter provided on the rotary shaft of the photosensitive drum for measurement, the magnetic brush is a magnetic brush frictional force F ₁ from the torque variation when in contact with the drum surface (photosensitive member surface) by performing the developing operation in this state the load sensing means is provided on the rotating drum surface, while the position fixing the drum, by performing development operation, it calculates the developing pressure F _2, calculation formula, B = F ₁ / F ₂ from the dynamic friction coefficient μ is Is done. Further, the friction coefficient of the photoreceptor is measured by peeling a part of the coating film and attaching the film on an aluminum plate, and measuring the surface friction coefficient with an automatic friction and wear analyzer (DFPM-SS type) manufactured by Kyowa Interface Science Co., Ltd. In the present invention, in order to reduce the surface friction coefficient of the photoreceptor, a lubricating resin or resin powder, a surfactant or the like may be dissolved or dispersed in the photosensitive layer surface layer.
In particular, an excellent effect can be obtained by including silicone oil. This is presumably because the surface of the photoreceptor is made smoother than when resin powder or the like is used based on the leveling action of the silicone oil, and wear due to friction with the magnetic brush is suppressed. In the present invention, the effect is best exhibited when the viscosity of the silicone oil is 100 cs or less. Although the effect of the present invention can be sufficiently obtained when the viscosity is 100 cs or more, the adhesion is slightly increased due to the high viscosity.

The silicone oil that can be used in the present invention may be any commercially available silicone oil. For example, in addition to straight silicone oils such as dimethyl silicone oil, methyl phenyl silicone oil, and methyl hydrogen silicone oil, besides straight silicone oils. Any of various modified silicone oils represented by, for example, alkyl-modified, amino-modified, carboxyl-modified, higher fatty acid-modified, epoxy-modified, alcohol-modified, polyether-modified, alkyl / polyether-modified, and fluorine-modified can be preferably used. These silicone oils may be added to the photoreceptor surface layer to such an extent that a desired coefficient of friction can be obtained. As a rule, about 0.01 to 5% of the resin amount of the added layer is used. preferable.

The method for measuring the characteristic value of the developer in the present invention will be described below. (1) Magnetic properties of carrier: BHU-60
Type magnetization measurement device (manufactured by Riken Keisokusha) is used. Specifically, about 1.0 g of a measurement sample is weighed, packed in a cell having an inner diameter of 7 mmφ and a height of 10 mm, and set in the above-mentioned apparatus. In the measurement, an applied magnetic field is gradually applied to change the maximum to 3,000 Oe. Next, the applied magnetic field is decreased, and finally a hysteresis curve of the sample is obtained on the recording paper. From this, the saturation magnetization, residual magnetization, and coercive force are obtained. (2) Measurement of the particle size distribution of the carrier: The measurement was performed using an SRA type Microtrac particle size analyzer (manufactured by Nikkiso Co., Ltd.) at a setting of 0.7 to 125 μm. (3) Measuring Method of Toner Particle Size 0.1 to 5 ml of a surfactant (alkylbenzene sulfonate) is added to 100 to 150 ml of the above-mentioned electrolyte solution, and 2 to 20 mg of a measurement sample is added thereto. The electrolytic solution in which the sample was suspended was subjected to dispersion treatment for 1 to 3 minutes with an ultrasonic disperser, and 10
2 to 4 based on volume using a 0 μm aperture
A particle size distribution of 0 μm is measured.

(Examples) Next, the present invention will be described in more detail with reference to examples. However, the present invention is not limited by the following examples. In the examples, all parts are parts by weight. Example 1 (Preparation of toner) 80 parts of polyester resin 20 parts of styrene-methyl acrylate copolymer 20 parts of carnauba wax 5 parts of carbon black 8 parts of metal-containing monoazo dye 3 parts After sufficiently stirring and mixing these mixtures in a Henschel mixer, About 30 at a temperature of 130-140 ° C with a roll mill
The mixture was heated and melted for one minute, cooled to room temperature, and the kneaded product was pulverized and classified by a jet mill to obtain a classified product having a particle size of 7.5 μm. To 100 parts of the classified product, 0.8 part of silica oil-treated silica fine particles and 0.2 part of titanium oxide fine particles were used.
Parts were added and mixed to obtain a toner. (Preparation of Carrier and Developer) Silicone resin solution 100 parts Carbon black 4 parts Toluene 100 parts These formulations were dispersed with a homomixer for 30 minutes to prepare a coating layer forming liquid. A coating layer was formed on the surface of 1000 parts of ferrite having a volume average particle size of 45 μm by using a fluidized bed type coating apparatus to prepare a carrier. 2.5 parts of the toner prepared as described above and 97.5 parts of the carrier were mixed by a ball mill to obtain a two-component developer.

(Preparation of photoreceptor) Undercoat layer alkyd resin 15 parts Melamine resin 10 parts Titanium oxide powder 90 parts Methyl ethyl ketone 150 parts These formulations were dispersed in a ball mill for 12 hours to prepare an undercoat layer coating solution. This has an outer diameter of 10 mm and a length of 360 m
The resultant was dipped on an aluminum drum having a thickness of 4.5 m and dried at 140 ° C. for 20 minutes to form an undercoat layer having a thickness of 4.5 μm. Charge generation layer polyvinyl butyral resin 4 parts Trisazo pigment 10 parts Methyl ethyl ketone 700 parts These formulations were dispersed in a ball mill for 72 hours to prepare a charge generation layer coating solution. This is dip-coated on the undercoat layer,
After drying at 130 ° C. for 20 minutes, a charge generation layer having a thickness of 0.2 μm was formed. Charge transport layer polycarbonate resin 10 parts Triphenylamine compound 7 parts Tetrahydrofuran 85 parts After stirring and dissolving these formulations with a stirrer, 80 cs alcohol-modified silicone oil as silicone oil (KF-851 manufactured by Shin-Etsu Chemical Co., Ltd.) as a lubricating substance.
Was added and the mixture was further stirred for 1 hour and dispersed to prepare a charge transport layer coating solution. This was dip-coated on the charge generation layer and dried at 130 ° C. for 20 minutes to obtain a thickness of 25 μm.
m of the charge transport layer was formed.

(Measurement of Coefficient of Friction) When the coefficient of friction was measured for the electrophotographic photosensitive member and the developer thus manufactured, the relationship A / 2 + B between the surface friction coefficient A of the photosensitive member and the magnetic brush B was 0. 54. Tables 1 and 2 show the physical property measurement results.

(Evaluation of Image) The developer and the photoreceptor prepared as described above were used with a copying machine imagio655 manufactured by Ricoh Co., Ltd.
No. 0 and developed to evaluate the degree of background contamination and carrier adhesion. Initial and 100K sheets (1000
(00 sheets) Even after the run, carrier adhesion, image density and background stain were good. In addition, the amount of the charge transport layer film scraped after the 100K sheet run was almost nonexistent, and was very good. The carrier adhesion, the image density, and the background stain were ranked according to the degree, and ○ was set as a pass level, Δ was set as an allowable level, and x was set as an unacceptable level. The results are shown in Tables 3 and 4.

Example 2 (Preparation of Toner) The kneaded material obtained in Example 1 was pulverized and classified by a jet mill to obtain a classified product having a particle size of 6.0 μm.
To 100 parts of the classified product, 0.7 part of silica oil-treated silica fine particles and 0.3 part of titanium oxide fine particles were added and mixed to obtain a toner. (Preparation of Carrier and Developer) A carrier was prepared in the same manner as in Example 1 except that ferrite having a volume average particle diameter of 40 μm was used. (Production of photoconductor) A photoconductor was prepared in the same manner as in Example 1, except that the amount of silicone oil added at the time of photoconductor production was changed to 0.02 parts. (Evaluation of Image) The developer and the photoreceptor prepared as described above were evaluated for background stain and the degree of carrier adhesion in the same manner as in Example 1. The carrier adhesion, the image density, and the background stain were good at the initial stage and after the 100K sheet run. In addition, the amount of the charge transport layer film scraped after the 100K sheet run was almost nonexistent, and was very good. The physical property measurement results at this time are shown in Tables 1 and 2, and the image evaluation results are shown in Tables 3 and 4.

Example 3 (Preparation of developer) A developer was prepared in the same manner as in Example 1, except that ferrite having a volume average particle diameter of 45 μm and a low saturation magnetization was used at the time of preparing the carrier. . (Preparation of Photoconductor) The photoconductor drum prepared in Example 2 was used as it was. (Evaluation of Image) The developer and the photoreceptor prepared as described above were evaluated for background stain and the degree of carrier adhesion in the same manner as in Example 1. The initial carrier adhesion, image density and background stain were good. Even after the 100K sheet run, the image density and background stain were good, but carrier adhesion at an acceptable level occurred. The amount of scraping of the charge transport layer film after 100K runs was small and good. The physical property measurement results at this time are shown in Tables 1 and 2, and the image evaluation results are shown in Table 3.
And Table 4 below.

Example 4 (Preparation of a developer and a photoreceptor) A developer and a photoreceptor were prepared in the same manner as in Example 2, except that the silica particles were not treated with silicone oil when preparing the toner. . (Evaluation of Image) The developer and the photoreceptor prepared as described above were evaluated for background stain and the degree of carrier adhesion in the same manner as in Example 1. The carrier adhesion, the image density, and the background stain were good at the initial stage and after the 100K sheet run. Further, the amount of scraping of the charge transport layer film after running 100K sheets was small and good. The physical property measurement results at this time are shown in Tables 1 and 2, and the image evaluation results are shown in Tables 3 and 4.

Example 5 (Production of developer and photoreceptor) In Example 1, silica fine particles treated with silicone oil at the time of toner production were used.
A developer and a photoreceptor were prepared in the same manner as in Example 1 except that only 0 part was added and mixed. (Evaluation of Image) The developer and the photoreceptor prepared as described above were evaluated for background stain and the degree of carrier adhesion in the same manner as in Example 1. The initial carrier adhesion, image density and background stain were good. After the 100K sheet run, the charge amount increased and the image density and the background stain were good, but the carrier adhesion to the non-image area (permissible level) due to the counter charge slightly occurred. 100
The amount of scraping of the charge transport layer film after the K-sheet run was small and good. The physical property measurement results at this time are shown in Tables 1 and 2, and the image evaluation results are shown in Tables 2 and 4.

Example 6 (Production of developer and photoreceptor) In Example 1, silica fine particles treated with silicone oil at the time of toner production were prepared.
A developer and a photoreceptor were prepared in the same manner as in Example 1, except that 5 parts and 0.5 part of titanium oxide fine particles were added and mixed. (Evaluation of Image) The developer and the photoreceptor prepared as described above were evaluated for background stain and the degree of carrier adhesion in the same manner as in Example 1. The initial carrier adhesion, image density and background stain were good. After the 100K sheet run, the charge amount was reduced and the image density and the carrier adhesion were good, but the background stain (tolerable level) was slightly generated. The amount of scraping of the charge transport layer film after 100K runs was small and good. The physical property measurement results at this time are shown in Tables 1 and 2, and the image evaluation results are shown in Tables 3 and 4.

Example 7 (Preparation of developer and photoreceptor) In Example 1, a polyether-modified silicone oil having a viscosity of 180 cs (TSF4440 manufactured by Toshiba Silicone Co., Ltd.) was used as a lubricating substance in preparation of the photoreceptor instead of silicone resin fine particles. 0.005
A developer and a photoreceptor were prepared in the same manner as in Example 1 except that the addition was partially performed. (Evaluation of Image) The developer and the photoreceptor prepared as described above were evaluated for background stain and the degree of carrier adhesion in the same manner as in Example 1. The carrier adhesion, the image density, and the background stain were good at the initial stage and after the 100K sheet run. Further, the amount of scraping of the charge transport layer film after running 100K sheets was small and good. However, image defects due to coating unevenness on the photoreceptor surface were slightly generated. The physical property measurement results at this time are shown in Tables 1 and 2, and the image evaluation results are shown in Tables 3 and 4.

Comparative Example 1 (Preparation of Toner, Carrier, and Developer) In Example 1, a toner was prepared in the same manner as in Example 1 except that magnetite having a volume average particle diameter of 45 μm and high saturation magnetization was used when preparing the carrier. , A carrier and a developer. (Preparation of Photoreceptor) A photoreceptor was prepared in the same manner as in Example 1, except that fine particles of silicone resin were not added. (Evaluation of Image) The developer and the photoreceptor prepared as described above were evaluated for background stain and the degree of carrier adhesion in the same manner as in Example 1. The initial carrier adhesion, image density and background stain were good. After the 100K sheet run, the image density and carrier adhesion were good, but background stains had occurred. The amount of film scraping of the charge transport layer after the 100K sheet run was large, and the image scraping caused a decrease in image density and background fouling. Tables 1 and 2 show the physical property measurement results at this time.
Table 3 and Table 4 show the image evaluation results.

Comparative Example 2 (Production of Toner, Carrier, Developer, Photoconductor) Example 5
The volume average particle size is 45 μm
Example 5 except that ferrite having a low saturation magnetization was used.
A toner, a carrier, a developer, and a photoreceptor were prepared in the same manner as described above. (Evaluation of Image) The developer and the photoreceptor prepared as described above were evaluated for background stain and the degree of carrier adhesion in the same manner as in Example 1. Although the initial image density and background stain were good, carrier adhesion (tolerable level) was slightly generated. After the 100K sheet run, the image density was low, and background stain and carrier adhesion occurred. 100
The amount of the charge transport layer film abrasion after the K-sheet run was large, and the image abrasion caused image density reduction and background fouling. The physical property measurement results at this time are shown in Tables 1 and 2, and the image evaluation results are shown in Tables 3 and 4.

[0060]

[Table 1]

[0061]

[Table 2]

[0062]

[Table 3]

[0063]

[Table 4]

[0064]

As described above, according to the first aspect of the present invention, there is provided an image in which an electrostatic latent image formed on an electrophotographic photosensitive member containing a silicone oil in a surface layer is developed using a two-component developer. In the forming method, the weight average particle diameter of the non-magnetic toner is 5
10 μm, weight average particle size of the magnetic carrier is 15 to 45
μm, the surface friction coefficient A of the photoreceptor and the dynamic friction coefficient B of the magnetic brush have the above-described relationship. And the amount of wear on the surface of the photoreceptor due to friction of a magnetic brush or the like can be reduced, and a high-definition image can be obtained without scratches and density reduction on the image even during long-term use.

According to the second aspect of the present invention, since the saturation magnetization of the magnetic carrier is 50 to 90 emu / g, it is possible to improve the effect of preventing the carrier from adhering during the initial stage and during the run time.

According to the third aspect of the present invention, since the additives to be externally added to the toner are fine particles of silica and fine particles of titanium oxide, the effect of preventing the carrier from adhering at the initial stage and during the run is excellent, and the background portion is not stained. Excellent images can be obtained.

According to a fourth aspect of the present invention, since the addition ratio of the silica fine particles and the titanium oxide fine particles is titanium oxide fine particles / silica fine particles <0.6, it is possible to prevent a decrease in the charge amount during printing. it can.

According to the fifth aspect of the present invention, since the silica fine particles are treated with a treating agent containing silicone oil, a better result can be obtained in reducing the friction on the surface of the photoreceptor.

According to a sixth aspect of the present invention, since the viscosity of the silicone oil contained in the surface layer of the photoreceptor is 100 cs or less, the surface friction coefficient of the photoreceptor is favorably reduced.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) G03G 15/09 G03G 15/09 Z 21/10 21/00 310 (72) Inventor Yasutaka Iwamoto Ota-ku, Tokyo 1-3-6 Nakamagome, Ricoh Co., Ltd. (72) Inventor Hiroaki Matsuda 1-3-6 Nakamagome, Ota-ku, Tokyo Co., Ltd. Ricoh Co., Ltd. (72) Inventor Naoto Shimoda 1-Chome, Nakamagome, Ota-ku, Tokyo No. 3-6 Inside Ricoh Company (72) Inventor Hiroshi Nakai 1-3-6 Nakamagome 1-chome, Ota-ku, Tokyo Inside (72) Inventor Kazuyuki Yazaki 1-3-6 Nakamagome, Ota-ku, Tokyo No. Ricoh Co., Ltd. (72) Inventor Kumi Hasegawa 1-3-6 Nakamagome 1-chome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Hiroto Higuchi 1 Nakamagome, Ota-ku, Tokyo 3-6 in Ricoh Co., Ltd. (72) Inventor Akemi Sugiyama 1-3-6, Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. (reference) 2H005 AA08 CA12 CB07 CB13 EA02 EA05 EA07 2H031 AD01 BA08 BA09 2H034 AA07 2H068 AA14 BB34 FA03

Claims (6)

[Claims] An electrostatic latent image formed on a surface layer of an electrophotographic photoreceptor using a silicone oil by using a charging and exposing means is formed of a non-magnetic toner and a magnetic carrier. In the image forming method of performing development using a developer, when the weight average particle diameter of the toner is 5 to 10 μm and the weight average particle diameter of the carrier is 15 to 45 μm,
An image forming method, wherein the following relationship is established, where A is the surface friction coefficient of the electrophotographic photosensitive member and B is the dynamic friction coefficient of the magnetic brush. A / 2 + B ≦ 0.55 2. A magnetic carrier having a saturation magnetization of 50 to 9
2. The image forming method according to claim 1, wherein the value is 0 emu / g. 3. The image forming method according to claim 1, wherein the additive externally added to the toner contains silica fine particles and titanium oxide fine particles. 4. The addition ratio of the silica fine particles and the titanium oxide fine particles is such that titanium oxide fine particles / silica fine particles <0.6.
The image forming method according to claim 3, wherein 5. The image forming method according to claim 3, wherein the fine silica particles are treated with a treating agent containing silicone oil. 6. The image forming method according to claim 1, wherein the viscosity of the silicone oil contained in the surface layer of the electrophotographic photosensitive member is 100 cs or less.