JPH07104610B2 - Image forming method - Google Patents

Description

The present invention relates to an image forming method using a one-component developer composed of a magnetic toner used in electrophotography, electrostatic recording and electrostatic printing. It is a thing.

BACKGROUND OF THE INVENTION Generally, in electrophotography, a latent electrostatic image bearing member having a photosensitive layer made of a photoconductive material, that is, a photosensitive member is subjected to imagewise exposure after uniform electrostatic charge is applied thereto. An electrostatic latent image is formed on the surface, and the electrostatic latent image is developed with a developer to form a toner image. The obtained toner image is transferred to a transfer material such as paper and then fixed by heating or pressing to form a copy image.

Known selenium photoconductors, zinc oxide photoconductors, cadmium sulfide photoconductors, organic photoconductors, and the like are known as photoconductors.However, selenium photoconductors have poor heat resistance such as easy crystallization in a high-temperature environment and have characteristics such as sensitivity. It has a problem that it deteriorates and becomes an unclear image. Further, in the case of a zinc oxide photoconductor or a cadmium sulfide photoconductor, the photosensitivity is likely to be deteriorated early by image exposure, fog may occur and a clear image may be formed, which is poor in durability, and toxicity to the human body may be impaired. .

On the other hand, an organic photoconductor made of an organic semiconductor has advantages such as not having the above-mentioned drawbacks, good film-forming property, low manufacturing cost, high sensitivity, durability, heat resistance, and no toxicity to human body. It is a preferable photoreceptor having.

As for the polarity of the electrostatic latent image formed on the surface of the organic photoconductor, a negative electrostatic latent image is generally used, except for exceptional ones. This is based on the fact that there are many types of photoconductive substances that constitute the organic photoconductor and that high performance can be exhibited.

As a method of developing an electrostatic latent image, a wet developing method and a dry developing method are known. The former wet development method has a problem that a bad odor is emitted because a liquid developer is used, and high energy is required to dry the transfer material, which makes high-speed copying difficult. The latter dry developing method does not have such problems and is a preferable method as a developing method of an electrostatic latent image.

The developer used in the dry development method is generally composed of a so-called two-component developer composed of a non-magnetic toner containing no magnetic substance and a carrier having magnetism, and a magnetic toner containing a magnetic substance. A so-called one-component developer is known.

Since the former two-component developer consumes only toner as the development proceeds, it is necessary to maintain the mixing ratio of the toner to the carrier, that is, the toner concentration within a specific range. However, there is a drawback that a complicated and expensive toner replenishing device that can sufficiently adjust the toner density is required. That is, when the toner density is too low, it becomes difficult to form a toner image having a sufficient density in the developing process, and as a result, the final fixed image has a low image density and becomes an unclear image. On the other hand, when the toner concentration is too high, it is difficult to apply proper frictional charge to the toner because the chance of frictional contact between the toner and the carrier is reduced, and as a result, image defects such as fog occur in the image. There is a problem that the image quality deteriorates.

On the other hand, the latter one-component developer does not have the above problems. That is, since the toner is made of only magnetic toner, it is not necessary to adjust the toner concentration. Therefore, a toner replenishing device is not required, maintenance is easy, and a device for agitating the developer is not required. It has the advantage that it can be

However, in the one-component developer, since the magnetic toner is composed of only the magnetic toner and does not have a carrier, the magnetic toner has a strong magnetic cohesive force and electrostatic cohesive force, so that the magnetic toners are aggregated and agglomerated. There is a problem that the fluidity of the developer is further reduced, an appropriate amount of toner cannot be stably conveyed to the developing space, and the image density is reduced or image unevenness occurs.

Further, when the magnetic toner has low fluidity, the magnetic toner is likely to agglomerate. Therefore, in the developing device, the magnetic toner is mixed with each other, or the magnetic toner and the device wall inside the developing device, the regulation blade, the developer carrying member, etc. However, there is a problem in that the final fixed image becomes fogged and unclear, as a result.

Therefore, in order to improve the fluidity of the magnetic toner, it is effective to add the inorganic fine powder to the magnetic toner. Conventionally, the following techniques have been proposed.

(1) A technique for incorporating fine powder of hydrophobic silica represented by Aerosil R-972.

(JP-A-53-59430) (2) A technique of incorporating an inorganic fine powder treated with an aminosilane coupling agent.

(JP-A-52-135739, JP-A-56-123550) (3) A technique of incorporating an inorganic fine powder treated with silicone oil having an amino group in a side chain.

(Japanese Patent Laid-Open Nos. 59-200252 and 59-201063) However, when developing a negatively charged latent image formed on an organic photoconductor, the polarity of the magnetic toner must be positively charged. In the technique (1), since the hydrophobic silica fine powder is negatively charged, not only positively charged toner but also negatively charged toner are present.

At the outer edge of the solid black image, the electric field strength becomes smaller than that at the white background due to the edge effect, and when a bias voltage is applied, the outer edge of the solid black image appears to be oppositely charged and is charged with the negative band charge described above. Fog, which is so-called fringe, is generated by developing with the toner. In particular, when the image is formed under high temperature and high humidity, the toner charge is likely to leak due to the absorbed paper in the transfer process of transferring the image onto paper, but when the toner charge amount is small, a poor transfer results in a good image. I can't get it. In the technique (1), the transfer failure occurs because the charge amount of the toner is small.

Further, since the charge amount of the toner is small, sufficient developability cannot be obtained in the developing process. Also, in the cleaning step, the toner remaining on the surface of the photoconductor is usually scraped off by a blade or the like. Especially, in the case of an organic photoconductor, the hardness of the photoconductor is small. Toner that cannot be cleaned is deposited on the photoconductor as a nucleus, and an image defect called a black spot occurs on the image.

Further, in the above technique (2), since the fine powder of the metal oxide treated with the aminosilane coupling agent is used, the fine powder can be positively charged, so that the negatively charged toner is significantly reduced. Therefore, so-called fringes are not generated and the developability can be improved.
The surface of the metal oxide fine powder treated with the aminosilane coupling agent is made hydrophobic by the coupling agent, but since all the hydrophilic groups cannot be made hydrophobic, water is easily adsorbed and an image is formed under high humidity. If it is carried out, it causes a transfer failure and a decrease in developability. Also, black spots are generated due to poor cleaning.

Further, in the above technique (3), since the metal oxide fine powder treated with silicone oil having an amino group in the side chain is used, the fine powder can be positively charged as in the technique (2). It is necessary to increase the amount of amino groups introduced in order to sufficiently improve the charging property. In this case, the occurrence of fringes can be eliminated and the developability can be improved,
Since the developer greatly depends on the environment, when an image is formed especially under high humidity, transfer failure and deterioration of developability are caused. Also, black spots, which are poor cleaning, occur.

As described above, in any case, it is difficult to repeatedly obtain a good image under any environment.

[Object of the Invention] The present invention has been made in order to solve the above-mentioned conventional problems, and an object of the present invention is to provide (1) an image forming method using a highly developable one-component developer. To provide,
(2) To provide an image forming method using a high-quality one-component developer that does not cause fringes, and (3) provides high developability, high transferability, and high image quality in any environment that does not depend on the environment. To provide an image forming method using the obtained one-component developer, and (4) to provide an image forming method using the one-component developer capable of performing a stable image forming process without occurrence of cleaning failure. It is in.

[Means for Achieving the Object] The object of the present invention is to form an image having a step of developing an electrostatic latent image formed on a photoconductor with a developer by a magnetic brush development method, and a cleaning step with a cleaning member. In the method, the photoreceptor is an organic photoreceptor, the electrostatic latent image is a negative electrostatic latent image, the cleaning member is a cleaning blade made of urethane rubber, and the developer is an ammonium salt functional group. Inorganic fine particles obtained by surface-treating a polysiloxane containing a constitutional unit represented by the following formula (A) (hereinafter sometimes referred to as "specific inorganic fine particles") and magnetic fine particles dispersed in a binder resin. The magnetic toner is mixed with the magnetic toner, and the content ratio of the inorganic fine particles is 0.
It can be achieved by an image forming method characterized by being a one-component type developer of 1 to 5% by weight.

Formula (A) (Here, R ₁ is a hydrogen atom, a hydroxy group, an alkyl group,
Aryl group, alkoxy group, or R ₂ represents a bonding group or a simple bond, R ₃ , R ₄ and R ₅ each represent a hydrogen atom, an alkyl group or an aryl group, and X represents a halogen atom. Each group represented by R _{1 to} R ₅ includes those having a substituent. [Advantageous effects of the present invention] In the present invention, by adding the specific inorganic fine particles to the one-component developer, it has good positive chargeability and excellent moisture resistance. It is possible to achieve developability and high transferability, and obtain a high-quality image without fringes. That is, the specific inorganic fine particles are obtained by treating the surface of the inorganic fine particles with polysiloxane having an ammonium salt as a functional group. The functional groups of ammonium salts have a higher positive charge density than amino groups. Therefore, high positive chargeability can be imparted. In addition, by using a polysiloxane polymer as the coupling agent, which is a monomer, the surface of the inorganic fine particles can be uniformly covered, and therefore, hydrophilic sites and negatively charged sites (for example, -OH groups) existing on the surface of the inorganic fine particles can be obtained. Does not remain on the surface, which makes it possible to impart a high positive chargeability even under high humidity environment conditions as under normal humidity conditions.

Then, since the developer is provided with fluidity by the specific inorganic fine particles, the magnetic toner particles are not agglomerated and are triboelectrically charged in a stable state.

Furthermore, in the case of inorganic fine particles obtained by treating polysiloxane having a functional group of ammonium salt having a small adhesiveness and relatively softness, the adhesiveness is small even on the surface of the organic photoconductor, which is relatively easy to film, and slightly. Even if it adheres to, it can be easily cleaned with a cleaning blade. Further, since the toner particles formed by adhering the specific inorganic fine particles to the magnetic toner surface come into contact with the organic photoconductor surface through the specific inorganic fine particles having low adhesiveness, the toner organic photoconductor surface Filming to the surface of the photoconductor and the adhesion of the toner particles to the surface of the photoconductor can be reduced, so that the cleaning property of the residual toner on the surface of the photoconductor is improved. Therefore,
There is no image defect called black spot due to poor cleaning.

Further, according to the one-component developer of the present invention, the negative electrostatic latent image formed on the surface of the organic photoconductor is developed, so that the advantage of the organic photoconductor that the production cost is low and there is no toxicity is impaired. The negative electrostatic latent image formed on the organic photoconductor can be satisfactorily developed without causing scattering of developer particles or cleaning failure, and in particular, the fluidity of the developer is good. It is possible to form a uniform and uniform magnetic brush of the developer on the developing sleeve, and therefore it can be preferably used in the magnetic brush developing method.

[Specific Structure of the Invention] The polysiloxane having an ammonium salt as a functional group, which is used in the specific inorganic fine particles of the present invention, is a dimethylpolysiloxane having an ammonium base having high positive chargeability and hardly causing cleaning failure. It is preferable. The dimethylpolysiloxane having an ammonium base is generally a dimethylsiloxane containing a structural unit represented by the following formula (A), and is represented by, for example, a structural formula of the formula (B).

Formula (A) (Here, R ₁ is a hydrogen atom, a hydroxy group, an alkyl group,
Aryl group, alkoxy group, or The stands, R ₂ is a bond group (e.g., an alkylene group, an arylene group, aralkylene group, -NH -, - NHCO-, or group, and the like in any combination of these groups),
Alternatively, it represents a simple bond, R ₃ , R ₄ and R ₅ each represent a hydrogen atom, an alkyl group or an aryl group, and X represents a halogen atom. Each group represented by R _{1 to} R ₅ includes those having a substituent. ) (B) formula (Here, R ₆ and R ₇ each represent a hydrogen atom, a hydroxy group, an alkyl group, an aryl group or an alkoxy group, and these groups include those having a substituent. R ₁ to
R ₅ and X have the same meanings as R _{1 to} R ₅ and X in the formula (A). m and n each represent an integer of 1 or more. ) Also, Specific examples include, but are not limited to, those represented by the following structural formulas.

(6) -C₃H₆-N (CH₃)₃・ Cl   Polysiloxane having ammonium salt as a functional group
As a method of obtaining, an ammonium salt is used as a functional group.
Organohalogenated silane and especially ammonium base
Polymerization stage using organohalogenated silanes without
Organo method by introducing by copolymerization on the floor
Polysiloxaes obtained by polymerization with halogenated silanes.
An organic group having an ammonium salt as a functional group
It can be obtained by a method of partially modifying it. here
In place of organohalogenated silane
Xysilane may be used. Also, for some compounds
Can also be obtained as a commercial product.

Examples of the inorganic fine particles used for surface-treating the polysiloxane having an ammonium salt as a functional group include silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, and oxides. Examples thereof include fine particles of chromium, cerium oxide, antimony trioxide, zirconium oxide, silicon oxide and the like. The average particle diameter of the primary particles (particles separated into individual unit particles) of such inorganic fine particles is preferably within the range of 3 m to 2 m.

As the inorganic fine particles, silica fine particles can be particularly preferably used in order to improve the fluidity. The silica fine particles are fine particles having a Si—O—Si bond, and may be either one produced by a dry method or a wet method, but one produced by a dry method is preferable, and a silica halogen compound is particularly preferable. It is preferably silica fine particles produced by vapor phase oxidation. Further, as the silica fine particles, in addition to silicon dioxide (silica), fine particles made of silicates such as aluminum silicate, sodium silicate, calcium silicate, potassium silicate, zinc silicate, and magnesium silicate may be used. It is good, but those containing 85% by weight or more of SiO ₂ are preferable.

As a method for treating the polysiloxane having the ammonium salt as a functional group on the surface of the inorganic fine particles, a known technique can be used. Specifically, for example, in a solution prepared by dissolving the polysiloxane in a solvent, After dispersing the fine particles, the solvent is removed by filtration or the spray dry method, and then dried and cured by heating, or a solution of the polysiloxane dissolved in the solvent is sprayed on the inorganic fine particles using a fluidized bed device. A method in which the solvent is removed by applying and then drying by heating to form a film can be used.

The particle size of the specific inorganic fine particles thus obtained is such that the average particle size of the primary particles is 3 mμ to 2 μm, particularly 5 mμ to 50 μm.
It is preferably within the range of 0 mμ. Also, BET
The specific surface area according to the method is preferably 20 to 500 m ² / g. When the average particle diameter is too small or the specific surface area is too large, for example, when cleaning is performed using a blade-type cleaning device, the inorganic fine particles may easily slip through, and cleaning failure may occur. On the other hand, when the average particle diameter is too large or the specific surface area is too small, the fluidity of the developer decreases and the charging property becomes unstable,
As a result, durability may decrease.

When the one-component type developer is formed by using the specific inorganic fine particles, the specific inorganic fine particles are added to and mixed with the particle powder of the magnetic toner from the outside to adhere to the surface of the toner particles. Contained in.

The content ratio of the specific inorganic fine particles is 0.1 of the magnetic toner.
~ 5% by weight, especially 0.1-2% by weight
Is preferred. When the content ratio of the specific inorganic fine particles is too small, the fluidity of the developer may be lowered, and as a result, the triboelectric chargeability of the magnetic toner becomes poor and the toner is given a positive charge of an appropriate charge amount. It becomes difficult to do so, and fog may occur. Further, when the content ratio is excessively large, a part of the specific inorganic fine particles may exist in a state of being separated from the toner particles,
As a result, the released specific inorganic fine particles adhere to and accumulate on the inner wall of the developing device, the developing sleeve, the regulating blade, etc., and eventually the triboelectric chargeability of the toner becomes poor, and the toner is given a positive charge of a proper charge amount. Fogging,
Image density may be reduced.

The magnetic toner is a particle powder composed of a binder resin containing a colorant, magnetic fine particles, and other additives. The average particle size of magnetic toner is usually 5 to 20μ.
It is preferably about m.

The binder resin that constitutes the magnetic toner is not particularly limited, and a conventionally known resin can be used. Examples of suitable heat fixing methods include styrene resins,
Examples thereof include styrene-acrylic resin, styrene-butadiene resin, polyester resin, epoxy resin, polyamide resin and polyurethane resin. Also,
Suitable for the pressure fixing method are polyolefins such as polyethylene, polypropylene and polytetrafluoroethylene; ethylene-vinyl acetate copolymers, ethylene-acrylic acid ester copolymers, polyethylene-methacrylic acid ester copolymers. Polyethylene copolymers such as; polyesters; styrene-butadiene copolymers; waxes such as beeswax, carnauba wax, microcrystalline wax; higher fatty acids such as stearic acid and palmitic acid and salts thereof and esters thereof; epoxy resins; Examples thereof include rubbers such as isobutylene rubber, cyclized rubber and nitrile rubber; polyamide; chlorone-indene resin; maleic acid-modified phenol resin; phenol-modified terpene resin; silicone resin. As the binder resin for the magnetic toner, polyester resin and styrene-acrylic resin are preferably used.

The polyester resin preferably used as the binder resin of the magnetic toner is obtained by polycondensation of an alcohol monomer and a carboxylic acid monomer. Examples of the alcohol monomer used include ethylene glycol, diethylene glycol and triethylene glycol. , 1,2-propylene glycol, 1,3-propylene glycol, 1,4-
Butanediol, neopentyl glycol, diols such as 1,4-butenediol, 1,4-bis (hydroxymethyl) cyclohexane, bisphenol A, hydrogenated bisphenol A, polyoxyethylenated bisphenol A, polyoxypropyleneated bisphenol Examples thereof include etherified bisphenols such as A and other divalent alcohol monomers. Examples of the carboxylic acid monomer include maleic acid, fumaric acid, mesaconic acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, sebacic acid, Examples thereof include malonic acid, anhydrides of these acids, dimers of lower alkyl esters and linoleic acid, and other divalent organic acid monomers.

In addition to the above divalent monomers, if necessary, trivalent or higher polyvalent monomers may be used. Examples of the trihydric or higher polyhydric alcohol monomer include sorbitol,
1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, sucrose, 1,2,4-butanetriol, 1,2,5-pentatriol, Examples thereof include glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3,5-trihydroxymethylbenzene and the like. Examples of trivalent or higher polyvalent carboxylic acid monomers include 1,2,4-benzenetricarboxylic acid, 1,3,5-benzenetricarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid and 2,5 , 7-Naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,4
-Butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, tetra (methylenecarboxy)
Mention may be made of methane, 1,2,7,8-octanetetracarboxylic acid, empol trimer acid, and anhydrides of these acids, and others.

The styrene-acrylic resin that is preferably used as the binder resin of the magnetic toner is a resin obtained by copolymerizing a styrene monomer and an acrylic monomer. Specific examples of the styrene-based monomer include styrene and o.
-Methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-ethylstyrene, 2,
4-dimethylstyrene, pn-butylstyrene, pt
ert-butyl styrene, pn-hexyl styrene, p
-N-octyl styrene, pn-nonyl styrene, p
-N-decyl styrene, pn-dodecyl styrene, p
-Methoxystyrene, p-phenylethylene, p-chlorostyrene, 3,4-dichlorostyrene, etc. may be mentioned. These monomers may be used alone or in combination of two or more. Good. Specific examples of the acrylic monomer include acrylic acid, methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, n-octyl acrylate, dodecyl acrylate, lauryl acrylate. Acrylic acid such as 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, and methyl α-chloroacrylate, or esters thereof; methacrylic acid, methyl methacrylate, ethyl methacrylate, propyl methacrylate. , Methacrylic acid n-
Methacrylic acid such as butyl, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate or the like. Esters; Others can be mentioned, and these monomers may be used alone,
A plurality of items may be used in combination.

As the magnetic fine particles constituting the magnetic toner, substances that are strongly magnetized in that direction by a magnetic field, for example, iron, ferrite, magnetite and other iron, nickel, cobalt and other ferromagnets or alloys containing these metals are used. Alternatively, a compound, an alloy containing no ferromagnetic element but exhibiting ferromagnetism by appropriate heat treatment, for example, an alloy of the type called Heusler alloy such as manganese-copper-aluminum or manganese-copper-tin, or chromium dioxide. Etc. can be mentioned.

The magnetic fine particles are preferably uniformly dispersed and contained in the binder resin in order to obtain uniform magnetic properties, and from such a viewpoint, the average particle diameter is preferably 50 to 200 mμ, and particularly preferably 100 to 1000 mμ. . Further, the content ratio of the magnetic fine particles is preferably 15 to 65% by weight of the magnetic toner,
Particularly, 25 to 55% by weight is preferable. When the content is too small, toner scattering may occur. On the other hand, when the content is too large, it may be difficult to form a uniform magnetic toner layer on the developer carrying member, and uneven development may occur.

In addition to the binder resin and the magnetic fine particles, additives that are optionally used in obtaining the magnetic toner particles include, for example, a charge control agent and a release agent.

As the charge control agent, various pigments or dyes can be used. Specifically, nigrosine-based, azo-based, fourth
A pigment or dye such as a quaternary ammonium salt type or a thiourea type can be used. These charge control agents may be used in combination. The content ratio of the charge control agent is preferably 100 parts by weight of the total amount of the binder resin and the magnetic fine particles,
0.5 to 10 parts by weight, particularly preferably 1 to 5 parts by weight.

Examples of the release agent include polyolefin, fatty acid metal salt, fatty acid ester, partially saponified fatty acid ester, higher fatty acid, higher alcohol, liquid or solid paraffin wax, amide wax, polyhydric alcohol ester, silicone varnish, and aliphatic fluorocarbon. Etc. can be used. In particular, the softening point is 80-180 ℃, especially 70-160 ℃ when measured by the ring and ball method specified in JIS K2531-1960.
Polyolefins such as polyethylene and polypropylene are preferred. These release agents may be used in combination. The content of the release agent is preferably 1 to 10 parts by weight based on 100 parts by weight of the total amount of the binder resin and the magnetic fine particles.

When an image is formed using the developer of the present invention, an organic photoreceptor preferably used is, for example, a photoconductive semiconductor made of an organic compound dispersed in a resin binder on a conductive support made of aluminum, stainless steel or the like. It is configured by laminating the photosensitive layers.

Examples of the photosensitive layer include a styrene-methylmethacrylate copolymer and a polycarbonate resin as a carrier generating substance that absorbs visible light and generates a charge carrier, such as an anthanthrone compound, a perylene derivative, a bisazo compound, and a phthalocyanine compound. A carrier generation layer dispersedly contained in a binder resin such as a silicone resin,
For example, a carrier-transporting layer containing a carrier-transporting substance that transports carriers generated in the carrier-generating layer such as an oxadiazole derivative, a triarylamine derivative, a polyarylalkane derivative, a hydrazone derivative, a stilbene derivative, and a styryltriarylamine derivative. In order to improve the resolution, it is preferable to use a function-separated type photosensitive layer formed by combining and.

Next, an image forming process using the developer of the present invention will be described.

FIG. 1 shows an example of an image forming apparatus that can be suitably used for performing image formation using the developer of the present invention.

Reference numeral 10 denotes an organic photoconductor for forming an electrostatic latent image, and the organic photoconductor 10 has a rotary drum shape. Around the organic photoconductor 10, the corona charger 1, the exposure optical system 2, the magnetic brush developing device 3, the electrostatic transfer device 4, and the separator 5 are arranged in this order from the upstream side to the downstream side in the rotation direction. A blade type cleaning device 6 is arranged.

In the above apparatus, the developed surface of the organic photoreceptor 10 is charged to a uniform potential by the corona charger 1 and then imagewise exposed by the exposure optical system 2 to form an original on the developed surface of the organic photoreceptor 10. A corresponding electrostatic latent image is formed. And the developing device 3
Thus, a toner image corresponding to the document on which the electrostatic latent image has been developed is formed. The toner image on the organic photoconductor 10 is electrostatically transferred onto the transfer paper 8 by the electrostatic transfer device 4, and then the transfer paper 8 is transferred.
The upper toner image is heated and fixed by the heat roller fixing device 7 to form a fixed image. On the other hand, the organic photoconductor 10 that has passed through the electrostatic transfer device 4 becomes a clean surface even if the toner remaining on the surface is scraped off by the surface of the blade type cleaning device 6 being rubbed. After that, the corona charger 1 is again subjected to the charging process.

Specific Examples Hereinafter, specific examples of the present invention will be described, but the present invention is not limited to these examples.

(Production of Inorganic Fine Particles) (1) Inorganic Fine Particle A (for Present Invention) As a constituent unit, a polysiloxane having an ammonium salt shown below as a functional group was dissolved in xylene to prepare a treatment liquid.

Next, put silica fine particles "Aerosil 200" (manufactured by Nippon Aerosil Co., Ltd.) in a mixer, and
After spraying the polysiloxane of the above formula (1) at a ratio of 5% by weight, these are put in a flask and the xylene which is a solvent is removed for 5 hours at a temperature of 200 ° C. with stirring. Inorganic fine particles obtained by surface-treating polysiloxane having a salt as a functional group were obtained. This is designated as "inorganic fine particle A". This inorganic fine particle A
Had an average primary particle diameter of 12 mμ and a BET specific surface area of 115 m ² / g.

(2) Inorganic fine particles B (for the present invention) As its constituent unit, a polysiloxane having an ammonium salt shown below as a functional group is dissolved in xylene,
A treatment liquid was prepared.

Next, put silica fine particles "Aerosil 300" (manufactured by Nippon Aerosil Co., Ltd.) into a mixer, and with respect to the silica fine particles,
Surface-treated inorganic fine particles were obtained in the same manner as in the production of the inorganic fine particles A, except that the polysiloxane was sprayed at a ratio of 7% by weight. This is designated as "inorganic fine particle B". The inorganic fine particles B have an average primary particle diameter of 7 mμ,
The specific surface area according to the BET method was 126 m ² / g.

(3) Inorganic fine particles C (for the present invention) As its constituent unit, polysiloxane having the ammonium salt shown below as a functional group is dissolved in xylene,
A treatment liquid was prepared.

Next, silica fine particles "Aerosil 200" (manufactured by Nippon Aerosil Co., Ltd.) were put in a mixer, and the above polysiloxane was sprayed at a ratio of 10% by weight to the silica fine particles. The same treatment as in production was carried out to obtain surface-treated inorganic fine particles. This is "inorganic particles C"
And The inorganic fine particles C have an average primary particle diameter of 12
mμ, specific surface area by BET method was 93 m ² / g.

(4) Inorganic fine particles D (for comparison) Silica fine particles "Aerosil 200" (manufactured by Nippon Aerosil Co., Ltd.) were placed in a closed Henschel mixer heated to 100 ° C, and amino group-containing silicone oil was mixed with isopropyl alcohol. A solution (viscosity 1200 cps, amino equivalent 3500) dissolved in the above was stirred at a high speed while spraying at a ratio such that the amino group-containing silicone oil was 2.0% by weight, and then dried at a temperature of 150 ° C.,
Comparative inorganic fine particles whose surface was treated with the amino group-containing silicone oil were obtained. This is designated as "inorganic fine particle D".

(5) Inorganic fine particles E (for comparison) Silica fine particles “Aerosil 200” (manufactured by Nippon Aerosil Co., Ltd.) were placed in a closed Henschel mixer heated to 100 ° C., and the silica fine particles were treated with an amino group-containing silane coupling agent. A solution of a certain γ-aminopropyltriethoxysilane dissolved in alcohol was stirred at a high speed while spraying at a ratio such that the amino group-containing silane coupling agent was 5.0% by weight, and then dried at a temperature of 120 ° C. Thus, inorganic fine particles for comparison whose surface was treated with the amino group-containing silane coupling agent were obtained. These are referred to as "inorganic fine particles E".

(Production of magnetic toner) (1) Magnetic toner A1 styrene-acrylic copolymer (monomer composition; styrene: methyl methacrylate: butyl acrylate = 75: 1)
0:15, glass transition point Tg = 59 ° C) 50 parts by weight, magnetic fine particles (BL-100, magnetite, manufactured by Titanium Industry Co., Ltd.) 50 parts by weight, charge control agent (nigrosine dye, SO, Orient Chemical Co., Ltd.) 3 parts by weight and polypropylene (Viscole 660p,
3 parts by weight (manufactured by Sanyo Kasei Kogyo Co., Ltd.) are premixed with a Henschel mixer, and then 120 ° C. with an extruder.
Melt kneading at the temperature of, then cooling, coarse crushing, fine crushing with a jet mill, and further classification to obtain an average particle size of 10
A magnetic toner of μm was obtained. This is designated as "magnetic toner A1".

(2) Magnetic toner A2 Except that the amount of the styrene-acrylic copolymer used in the magnetic toner A1 was 55 parts by weight and the magnetic fine particles were 45 parts by weight of RB-BL (magnetite, manufactured by Titanium Industry Co., Ltd.). A “magnetic toner A2” was obtained in the same manner as the magnetic toner A1.

(3) Magnetic toner A3 Magnetic toner except that the amount of styrene-acrylic copolymer used in magnetic toner A1 was 40 parts by weight and 60 parts by weight of KOP-301 (ferrite, manufactured by TDK) was used as the magnetic fine particles. “Magnetic Toner A3” was obtained in the same manner as in A1.

(4) Magnetic toner A4 Magnetic toner A1 except that 3 parts by weight of cetylpyridinium chloride as a charge control agent and 3 parts by weight of polyethylene (Mitsui High Wax 400P, manufactured by Mitsui Petrochemical Industry Co., Ltd.) were used in place of polypropylene. “Magnetic Toner A4” was obtained in the same manner as A1.

(Production of Developer) 100 parts by weight of the magnetic toner A1 is mixed with the inorganic fine particles A.
By adding 0.4 parts by weight and mixing them with a Henschel mixer, the inorganic fine particles were made to adhere to and retained on the surface of the magnetic toner particles, whereby a one-component developer of the present invention was obtained. This is designated as "developer-1". Similarly, Developers-2 to 6 and Comparative Developers-1 to 3 having the configurations shown in Table 1 were prepared.

(Actual photo test) Electrophotographic copying machine "U
-Bix1200 "(manufactured by Konishi Rokusha Kogyo Co., Ltd.)
High temperature and high humidity environment condition of 0 ℃, relative humidity 80% and 25 ℃, 50
% Under normal temperature and normal humidity conditions, an actual copying test for forming a copied image was performed, and the following items were evaluated.

The image density of the white area of the image obtained by copying the band-shaped original image in which the fringe black area 1mm and the white area 1mm are repeated is the microdensitometer "Sakura densitometer PD
"M5" (manufactured by Konishi Rokusha Kogyo Co., Ltd.).

Image Density The density of the image obtained by copying the solid black original image was measured with a densitometer "Sakura densitometer PDA-65" (manufactured by Konishi Roku Photo Industry Co., Ltd.).

Cleaning property Repeated copying was performed and the presence or absence of black spots was visually confirmed.

Transfer rate A solid black original image is copied, and the toner weight A on the photoconductor when it is not transferred and the toner weight on the transfer paper after transfer
A ₁ was measured, and the transfer rate was calculated from the transfer rate (%) = A ₁ / A × 100.

The results are summarized in Table 2.

According to the results shown in Table 2, when the comparative developer is used, the developing property is lowered under high temperature and high humidity conditions, the image density is largely reduced due to transfer failure, and fringes are generated even under normal temperature and normal humidity conditions. Even with a small amount of copying, black spot defects occurred due to poor cleaning. On the other hand, when the developer of the present invention is used, even under high temperature and high humidity conditions, the decrease in image density is small, high developability and high transferability are exhibited, and a high-quality image free of fringes is obtained. Therefore, image defects due to poor cleaning do not occur.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of an image forming apparatus that can be suitably used for performing image formation using the developer of the present invention. 1 ... Corona charger, 2 ... Exposure optical system 3 ... Magnetic brush developing device, 4 ... Electrostatic transfer device 5 ... Separator, 6 ... Blade type cleaning device 7 ... Heat roller fixing device, 8 ...... Transfer paper 10 …… Organic photoreceptor

Claims (2)

[Claims] 1. An image forming method comprising a step of developing an electrostatic latent image formed on a photoreceptor by a magnetic brush developing method with a developer, and a cleaning step by a cleaning member, wherein the photoreceptor is an organic photoreceptor. The electrostatic latent image is a negative electrostatic latent image, the cleaning member is a cleaning blade made of urethane rubber, and the developer is represented by the following formula (A) having an ammonium salt as a functional group. Inorganic fine particles obtained by surface-treating polysiloxane containing a constitutional unit, and a magnetic toner in which magnetic fine particles are dispersed and contained in a binder resin are mixed, and the content ratio of the inorganic fine particles of the magnetic toner is 0.1
An image forming method, wherein the developing agent is a one-component developer having a content of 5 wt%. Formula (A) (Here, R ₁ is a hydrogen atom, a hydroxy group, an alkyl group,
Aryl group, alkoxy group, or R ₂ represents a bonding group or a simple bond, R ₃ , R ₄ and R ₅ each represent a hydrogen atom, an alkyl group or an aryl group, and X represents a halogen atom. Each group represented by R _{1 to} R ₅ includes those having a substituent. ) 2. The image forming method according to claim 1, wherein the inorganic fine particles are silica.