JPH087452B2 - Image forming method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention develops an electrostatic latent image, particularly a negative electrostatic latent image formed in an electrophotographic method, an electrostatic recording method, an electrostatic printing method or the like. The present invention relates to an image forming method using an electrostatic latent image developer.

BACKGROUND OF THE INVENTION Electrophotography is described in, for example, US Pat. Nos. 2,297,691 and 2,35.
No. 7,809, an electrostatic latent image is formed on the surface of the photoconductor, the electrostatic latent image is made into a toner image by a dry developer composed of colored particles, and then the toner is transferred onto a transfer sheet such as paper. This is a method of forming a copied image by transferring the image and then permanently fixing it by heating or pressing. On the other hand, the photosensitive member after the toner image is transferred is cleaned by the cleaning member to remove the toner remaining on the surface,
The image is formed again.

Known photoconductors used in such electrophotography include inorganic photoconductors such as selenium, zinc oxide and cadmium sulfide, and organic photoconductors composed of high molecular compounds or low molecular weight compounds such as polyvinylcarbazole. However, the selenium photoreceptor has a problem in that it is poor in heat resistance such as being easily crystallized in a high temperature environment and the characteristics such as sensitivity are deteriorated, resulting in an unclear image. In addition, in the case of a zinc oxide photoreceptor or a cadmium sulfide photoreceptor, the photosensitivity is easily deteriorated by image exposure at an early stage, fogging is generated, resulting in an unclear image and poor durability, and toxicity to the human body is accused. .

On the other hand, an organic photoconductor made of an organic semiconductor is a preferable photoconductor that has advantages such as good film-forming property, low manufacturing cost, high sensitivity, durability, heat resistance, and no toxicity to human body. is there.

As the polarity of the electrostatic latent image formed on the surface of the organic photoconductor, a negative electrostatic latent image is generally used. This is because there are many types of photoconductive substances that compose the organic photoconductor. It is based on the reason that it can exhibit high performance.

As the developers used for developing the negative electrostatic latent image formed on the surface of the organic photoreceptor, generally known are one-component developers and two-component developers. The former one-component developer is
It consists only of a magnetic toner in which a magnetic material or the like is dispersedly contained in a binder resin, and the latter two-component developer is composed of a toner and a carrier composed of magnetic particles.

When developing with such a developer, the toner forming the developer must be positively charged with the opposite polarity to the negative electrostatic latent image on the surface of the photoconductor. In the case of adding a positively chargeable charge control agent to positively charge the toner or in the case of a two-component developer, the toner is positively frictionally charged by further selecting a carrier.

However, it is not possible to stably provide a good image for a long period of time simply by positively charging the toner. That is, the toner is charged by rubbing against another friction charging member, but if it is repeatedly used many times, a part of the components constituting the toner is transferred to the friction charging member by friction, and the proper friction charging is performed. The surface of the triboelectrification member to which an electric charge should be imparted is contaminated, and it becomes impossible to impart an appropriate triboelectrification charge to the toner gradually, and the absolute value of the triboelectrification charge of the toner decreases, and fogging easily occurs and durability is impaired. I will end up.

In order to solve the above-mentioned problems, Japanese Patent Publication No. 53-22447 and Japanese Patent Laid-Open No. 53-66235 disclose that inorganic fine particles treated with an aminosilane coupling agent are internally added to the toner to impart positive chargeability. Attempts have been made,
As a result of studies conducted by the present inventors, such a developer exhibits some performance in the initial stage, but when it is repeatedly used many times, the performance is deteriorated, that is, the charging property is lost and fogging occurs. Toner is scattered to contaminate the image. Under high-humidity environmental conditions, the above defects become more remarkable. In addition,
In JP-A-56-123550 and JP-A-59-34539, silica fine particles treated with an aminosilane coupling agent or a silane coupling agent for hydrophobizing are used in combination with the toner to externally mix them, thereby improving charging property. Attempts have been made to improve stabilization, environmental stability, durability, etc., but when the present inventors studied, the silica particle surface before treatment has a large number of functional groups of Si-OH which is a hydrophilic group. Because
It is not possible to completely block the effect of humidity because the reaction with all the --OH groups and blocking cannot be achieved by simply treating the coupling agent, and a considerable --OH group remains on the silica particle surface. There will be drawbacks to change. That is, fog occurs due to a decrease in chargeability under many humid conditions or under high humidity conditions, and toner scatters to stain the image. In addition, JP-A-59-20106
In No. 3, an attempt was made to maintain durability by using a developer containing fine silicic acid powder treated with a silicone oil having an amine side chain, having stable chargeability even under changes in environmental conditions. However, as a result of investigations by the present inventors, since the surface of the silicic acid fine powder is treated with a sticky oil substance, it adheres to the triboelectric charging member such as the photoconductor surface, carrier particles, and developer carrier. It is liable to be contaminated, and the cleaning property of the surface of the photoconductor is deteriorated, and the triboelectric charging property of the toner is made unstable, and the durability is deteriorated.

An amine compound is used in the treated silica, but according to the study by the present inventors, it cannot be said to be sufficient from the viewpoint of positive charging ability, and such treated silica is externally added to the toner. In that case, since the charging ability is lower than that of the toner, the triboelectric charging property of the toner itself is rather reduced. Furthermore, when the toner is agitated together with carrier particles and the like in a developing device in order to make the toner triboelectrically charged and subjected to a physical force, the treated silica on the toner surface is easily transferred to another triboelectrification member to be contaminated. For this reason, the chargeability of the toner is lowered, and in such a developer, the adhesive force due to the Coulomb force between the toner particles and the carrier particles is lowered, the toner is scattered into the copying machine, and the image is also contaminated. Furthermore, the silica fine particles obtained by treating the conventional amine-based compound are likely to hinder the charging property of the toner,
Therefore, the triboelectrification efficiency is low. Therefore, even if such a developer has good performance at the beginning of use, the rise of charging is poor at the beginning of copying after continuous use. The image may be fogged or toner may be scattered. This phenomenon becomes more remarkable under high-humidity environmental conditions in which electric charges are likely to leak.

Further, when the present inventors apply the treated silica to an image forming method in which cleaning is performed with a cleaning blade, a cleaning failure does not occur in the initial stage, but a cleaning failure easily occurs when the number of copying increases. I found out.

In particular, when applied to an organic photoreceptor, it has been found that since the surface of the photoreceptor contains a resin component, the conventional treated silica tends to strongly adhere to the surface of the photoreceptor, resulting in poor cleaning. In particular, since components such as talc contained in the transfer paper also adhere to the surface of the photoconductor, they form agglomerated deposits on the surface of the photoconductor together with such components,
The function of electrostatic latent image formation is lost on the surface of the photoconductor in such a part, the image formation becomes insufficient, the image becomes thin and unclear "image blur", and such aggregated deposits are generated. It cannot be cleaned by the cleaning blade, resulting in poor cleaning.

As described above, when the conventional surface-treated silica is used, it does not have a positive charging property that is sufficiently stable against environmental changes, the charging efficiency is poor, the initial charging rise is poor, and cleaning failure is likely to occur. However, it has disadvantages such as poor durability.

[Object of the Invention] The present invention has been made in order to solve the above-mentioned conventional problems. The object of the present invention is, firstly, that the surface of the triboelectrification member is not contaminated and stable charging property is obtained. An object of the present invention is to provide an image forming method using an electrostatic latent image developer having excellent durability that can be maintained for a long period of time. Secondly, even under high temperature and high humidity environmental conditions, fog and toner scattering do not occur,
An object of the present invention is to provide an image forming method using an electrostatic latent image developer which is excellent in durability capable of obtaining a clear image for a long period of time and excellent in stability against environmental changes. Thirdly, the electrostatic latent image developer has a good charge rise even when copying is resumed after a pause, does not cause fogging or toner scattering even under high humidity environmental conditions, and can obtain a clear image. An object of the present invention is to provide an image forming method using. A fourth object is to provide an image forming method using an electrostatic latent image developer which is excellent in cleaning property and does not cause filming or damage on the surface of the photoconductor or the cleaning blade. Other objects will be readily apparent from the following description of the invention.

[Means for Achieving the Purpose] The various objects of the present invention include a step of developing an electrostatic latent image formed on a photoconductor with a developer by a magnetic brush developing method, and a cleaning step with a cleaning member. In the image forming method, the photoconductor is an organic photoconductor, 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. Inorganic fine particles obtained by surface-treating polysiloxane containing a constitutional unit represented by the following formula (A) having a functional group are added to the toner in an amount of 0.1 to 5
This can be achieved by an image forming method characterized in that the electrostatic latent image developer is a mixture of externally added by weight%.

Formula (A) (Here, R ₁ is a hydrogen atom, a hydroxy group, an alkyl group,
An aryl group, an 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 specific inorganic fine particles surface-treated with polysiloxane having an ammonium salt as a functional group to the developer, good positive chargeability can be obtained, and It has excellent moisture resistance, which can significantly improve durability. Since the functional group of the ammonium salt has a higher positive charge density than the amino group, a high positive chargeability can be imparted to the toner.

In addition, the use of the ammonium salt structure reduces the tackiness and reduces the adhesiveness, and prevents the triboelectrification member or the like from being attached and contaminated. In addition, since the surface of the inorganic fine particles can be uniformly covered by using a polysiloxane polymer as compared with the coupling agent which is a monomer, a large number of hydrophilic sites and negatively charged sites (for example, -OH
The base) does not remain on the surface, and thus it is possible to impart a high positive chargeability under high humidity environment conditions as under normal humidity conditions. In such a developer in which the specific inorganic fine particles are adhered to the toner surface, even if the developer is stirred in the developing device in order to make the triboelectric charging of the toner and the mixing of the toner and the carrier uniform, the specific inorganic fine particles are The transfer and adhesion to the inner wall of the developing device, the developing sleeve, the regulating blade, etc. are prevented, and as a result, the developer exhibits a stable positive charging property even when the image forming process is performed many times. Then, since the developer is provided with fluidity by the specific inorganic fine particles, the developer particles are not agglomerated and are triboelectrically charged in a stable state.
For this reason, the triboelectrification efficiency is high even after the suspension, and the rise of charging is quickly achieved, so that fogging and toner scattering can be prevented.

Further, in the case of inorganic fine particles which are treated with a polysiloxane having a functional group of a relatively soft ammonium salt having a small adhesiveness, the adhesiveness is small even on the surface of the organic photoconductor which is relatively easy to film, and Even if it adheres slightly, it can be easily cleaned with a cleaning blade. Further, the toner particles formed by adhering the specific inorganic fine particles on the toner surface come into contact with the organic photoconductor surface via the specific inorganic fine particles having low adhesiveness. Filming to the surface of the photoconductor and the adhesion of the toner particles to the surface of the photoconductor can be reduced. To do. Further, the specific inorganic fine particles adhered to the surface of the toner particles can prevent the toner particles from being attached to the carrier particles and the surface of the photoconductor and the surface deterioration due to the attachment, so that the composition change of the developer and the functional deterioration are prevented. A good developer can be provided.

Further, according to the developer of the present invention, the negative electrostatic latent image formed on the surface of the organic photoconductor is developed, so that the production cost is low and the toxicity of the organophotoreceptor is not impaired. The negative electrostatic latent image formed on the organic photoconductor can be satisfactorily developed without scattering of developer particles and cleaning failure, and in particular, the fluidity of the developer is good, so that the developing sleeve It is possible to form a uniform and uniform magnetic brush of the developer on the upper side, 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 contained in the 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 Wherein R ₂ is a bonding group (for example, an alkylene group, an arylene group, an aralkylene group, -NH-, -NHCO-, or a group obtained by combining these groups arbitrarily);
Or a mere 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. Equation (B) (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  (7) -C₃H₆-N H₃・ Cl  (9) -C₂H_Four-N H (CH₃)₂・ Cl  (11) -C₃H₆-NH-CO-N H₃・ Cl    Polysiloxane having an ammonium salt as a functional group
As a method for obtaining
Organohalogenated silanes and especially ammonium bases
Polymerization Using Organohalogenated Silanes Having No
Method introduced by copolymerizing in a stage, Olga
Polysiloxy obtained by polymerization using halogenated silane
An organic group having an ammonium salt as a functional group
It can be obtained by a method of denaturing a part thereof. This
Here, instead of the organohalogenated silane, an organoal
Coroxysilane may be used. For some compounds,
Also, it can be obtained as a commercial product.

As the inorganic fine particles used for the surface treatment with the polysiloxane having an ammonium salt as a functional group,
Examples thereof include fine particles of silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, chromium oxide, cerium oxide, antimony trioxide, zirconium oxide, silicon carbide 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 mμ to 2 μ.

As the inorganic fine particles, silica fine particles can be particularly preferably used in order to improve the fluidity. Silica fine particles are fine particles having a Si-O-Si bond, and may be any of those manufactured by a dry method and a wet method, but those manufactured by a dry method are preferable, and in particular, a silicon halide compound. It is preferable that the particles are silica fine particles generated 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, magnesium silicate and the like may be used. Although good, 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 the fine particles are dispersed, the solvent is removed by filtration or a spray drying method, followed by heating and drying and curing, or a solution in which the polysiloxane is dissolved in a solvent using a fluidized bed apparatus to form an inorganic fine particle. It is possible to use a method in which the solvent is removed by spray coating on, and then dried by heating to form a film.

The particle size of the specific inorganic fine particles thus obtained is
The average particle size of the primary particles is 3 mμ to 2 μ, especially 5 mμ to 50
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 size 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, the durability may decrease.

When the developer is formed by using the specific inorganic fine particles, the specific inorganic fine particles are contained in a state of being adhered to the surface of the toner particles by being externally added and mixed to the particle powder of the toner, A carrier and the like are further mixed with this.

The content ratio of the specific inorganic fine particles is 0.1 to 0.1% of the toner.
It is preferably 5% by weight, particularly preferably 0.1 to 2% by weight. 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 toner becomes poor, and a positive charge having an appropriate charge amount is imparted to the toner. This may cause fogging. Further, when the content ratio is too large, a part of the specific inorganic fine particles may exist in a state of being separated from the toner particles, and as a result, the separated specific inorganic fine particles may be attached and transferred to carrier particles, or The toner adheres to the inner wall of the developing device, the developing sleeve, the regulation blade, and the like, and eventually the triboelectric chargeability of the toner becomes poor, which makes it difficult to give a positive charge of an appropriate charge amount to the toner, resulting in fog. Image density may be reduced.

The electrostatic latent image developer of the present invention may basically be a one-component developer composed of only toner or a two-component developer composed of toner and a carrier having magnetism. Good.

The toner is a particle powder composed of a binder resin containing a colorant and other additives. The average particle size of the toner is usually preferably about 5 to 20 μm. Other additives include, for example, a fixability improver,
A charge control agent, a cleaning property improving agent, etc. can be used.

The binder resin for the toner is not particularly limited, and resins conventionally used for this type of application can be used. Specifically, for example, polystyrene resin, styrene-acrylic copolymer resin, poly-styrene-butadiene resin, polyester resin, epoxy resin and the like can be used. Of these, polystyrene resins, styrene-acrylic copolymers, and polyester resins can be preferably used as those having stable toner chargeability.

As the colorant, for example, carbon black, phthalocyanine blue, benzidine yellow, nigrosine dye, aniline blue, chalco oil blue, chrome yellow,
Dyes and pigments such as Ultramarine Blue, DuPont Oil Red, Quinoline Yellow, Methylene Blue Chloride, Malachite Green Oxalate, Lamp Black and Rose Bengal can be used.

As the cleaning property improver, for example, fatty acid metal salts such as zinc stearate, calcium stearate and stearic acid, and polymer particles such as methyl methacrylate particles and styrene particles can be used.

When the toner is a magnetic toner, a known magnetic material such as magnetite or ferrite can be used.

The carrier particles used in the case of the two-component developer are preferably particles having an average particle size of 15 to 200 μm, and substances that are strongly magnetized in that direction by a magnetic field, such as iron, ferrite, magnetite and other iron, nickel. , A metal or alloy exhibiting ferromagnetism such as cobalt, a compound containing these elements, an alloy not containing a ferromagnetic element but exhibiting ferromagnetism by appropriate heat treatment, such as manganese, copper, aluminum or manganese. Particles made of an alloy of a type called Heusler alloy such as copper and tin or chromium dioxide can be used.

In the image formation using the developer of the present invention, the organic photoconductor preferably used is a photoconductor in which a photoconductive semiconductor made of an organic compound is dispersed and contained in a resin binder on a conductive support made of aluminum, stainless steel or the like. It is configured by stacking layers.

As the photosensitive layer, for example, a styrene-methyl methacrylate copolymer, a polycarbonate resin such as an anthranthrone-based compound, a perylene-based derivative, a bisazo-based compound, and a carrier-generating material that generates a charged carrier by absorbing visible light, such as a phthalocyanine-based compound; , A carrier generation layer dispersed and contained in a binder resin such as a silicone resin,
For example, a carrier transport layer containing a carrier transport substance that transports carriers generated in the carrier generation layer such as an oxadiazole derivative, a triarylamine derivative, a polyarylalkane derivative, a hydrazone derivative, a stilbene derivative, and a styryltriarylamine derivative. It is preferable to use a photosensitive layer of a function separation type which is a combination of the above and for improving the resolution.

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 which can be suitably used for forming an image using the developer of the present invention.

Reference numeral 10 denotes an organic photoreceptor for forming an electrostatic latent image, and the organic photoreceptor 10 has a rotating drum shape. Around the organic photoconductor 10, the corona charger 1, the exposure optical system 2 and the exposure optical system 2 are arranged in this order from the upstream side to the downstream side in the rotation direction.
A magnetic brush 3, an electrostatic transfer device 4, a separator 5, and a blade type cleaning device 6 are 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. Then, the electrostatic latent image is developed by the developing device 3 to form a toner image corresponding to the original. The toner image on the organic photoconductor 10 is electrostatically transferred onto the transfer paper 8 by the electrostatic transfer device 4, and the toner image on the transfer paper 8 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 and comparative 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 Particles A (for the Present Invention) A polysiloxane having the following ammonium salt as a functional group as a constituent unit thereof was dissolved in xylene to prepare a treatment liquid.

Next, silica fine particles "Aerosil 200" (manufactured by Nippon Aerosil Co., Ltd.) are put in a mixer, and the silica fine particles are sprayed at a ratio of 5% by weight, and then put in a flask. While stirring, the solvent xylene was removed at a temperature of 200 ° C. for 5 hours to obtain inorganic fine particles obtained by surface-treating polysiloxane having an ammonium salt as a functional group. This is designated as "inorganic fine particle A". This inorganic fine particle A
The average particle size of the primary particles was 12 mμ, and the specific surface area measured by the BET method was 115 m ² / g.

(2) Inorganic fine particles B (for the present invention) A polysiloxane having an ammonium salt as a functional group shown below as a constitutional unit was dissolved in xylene to prepare a treatment liquid.

Next, except that silica fine particles "Aerosil 300" (manufactured by Nippon Aerosil Co., Ltd.) were placed in a mixer and sprayed at a ratio of 17% by weight of the above polysiloxane to the silica fine particles, the production of inorganic fine particles A was performed. The same treatment was carried out to obtain surface-treated inorganic fine particles. This is referred to as “inorganic fine particle B”. The inorganic fine particles B have an average primary particle diameter of 7 m.
μ, BET specific surface area was 126 m ² / g.

(3) Inorganic fine particles C (for the present invention) A treatment liquid was prepared by dissolving a polysiloxane having an ammonium salt represented by the following formula (3) as a functional group in xylene.

Next, silica fine particles “Aerosil 200” (manufactured by Nippon Aerosil Co., Ltd.) were placed in a mixer, and the above-mentioned polysiloxane was sprayed at a ratio of 10% by weight to the silica fine particles. The same treatment as in the production was performed 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, the specific surface area measured by the 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 an amino group-containing silicone oil was added to the silica fine particles with isopropyl alcohol. Solution (viscosity 1200 cps, amino equivalent 3500) was stirred at a high speed while spraying at a rate 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 referred to as “inorganic fine particles 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 70 ° 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. This is referred to as “inorganic fine particles E”.

(Production of Toner) 100 parts by weight of polystyrene-n-butyl acrylate copolymer (copolymerization weight ratio = 82: 18), 5 parts by weight of carbon black "# 30" (manufactured by Mitsubishi Kasei Co., Ltd.), and charged After mixing 2 parts by weight of the control agent "Nigrosine SO" (manufactured by Orient Chemical Co., Ltd.) and 3 parts by weight of polyolefin "Viscor 660P" (manufactured by Sanyo Kasei Co., Ltd.) with a V-type blender, the mixture was melted and kneaded with a two-roll mill, and thereafter. Cool, coarsely crush with a hammer mill, finely crush with a jet mill,
Next, it is classified by an air classifier, and the average particle size is 11.0μm.
Toner was obtained. This is referred to as “toner 1”.

(Production of Developer) To 50 parts by weight of Toner 1, 0.5 parts of the inorganic fine particles A are
By adding parts by weight and mixing them with a Henschel mixer, inorganic fine particles are adhered and held on the surface of the toner particles, and spherical ferrite particles "F-150" (manufactured by Nippon Iron & Powder Co., Ltd.) are further added to these. Career 9
By mixing 50 parts by weight, an electrostatic latent image developer of the present invention, which is a two-component developer, was obtained. This is referred to as "developer 1".
Similarly, Developers 2 and 3 and Comparative Developers 1 and 2 having the configurations shown in Table 1 were prepared.

(Actual photo test) <Actual photo test under high temperature and high humidity environment> It has an organic photoconductor for forming a negative electrostatic latent image, a contact type magnetic brush developing device, and a cleaning blade made of urethane rubber. Using a modified machine of the electrophotographic copying machine "U-Bix 1550MR" (manufactured by Konishi Rokusha Kogyo Co., Ltd.) equipped with a cleaning device, the above-mentioned developer under high temperature and high humidity environment conditions of temperature 30 ° C and relative humidity 80%. Using 1 to 3 and Comparative Developers 1 and 2, a copying test was performed for 50,000 times while performing a 5 hour pause for every 5000 copies, and the following items were evaluated. The results are shown in Table 2 below.

In the above organic photoconductor, a photosensitive layer having a negatively chargeable two-layer structure formed by using an anthrone pigment as a carrier-generating substance and a carbazole derivative as a carrier-transporting substance is used as a rotating drum-shaped conductive film made of aluminum. It is formed by stacking on a support.

The surface potential (maximum potential) during charging of the organic photoconductor is -700 V, the gap (Dsd) between the photoconductor and the developing sleeve in the developing space is 0.42 mm, and the distance between the tip of the regulating blade and the developing sleeve ( Hcut) is 0.40 mm, the magnet body is fixed, the magnetic flux density on the surface of the developing sleeve is 800 gauss, and the bias voltage applied to the developing sleeve is a DC voltage of -150V.

Fog "Sakura Densitometer" (made by Konishi Rokusha Kogyo Co., Ltd.)
Was used to measure the relative density of a white background portion having a document density of 0.0 with respect to the copied image, and the determination was made. The white background reflection density is set to 0.
It was set to 0. Evaluation is "○" when the relative concentration is less than 0.01
When the value was 0.01 or more and less than 0.03, it was marked as "△", and when it was 0.03 or more, it was marked as "x".

Evaluated by the fog of the item for the copied image after a pause of every 5000 copies of electrostatic charge rise.

Image quality The copied image was visually judged from the viewpoint of sharpness.
The evaluation was “Poor” when it was defective and practically problematic, “Δ” when it was slightly defective but at a practical level, and “◯” when it was good.

Toner scattering Visually observing the inside of the copying machine and the copied image. When toner scattering is hardly observed and is good, it is "○", when toner scattering is slightly observed but it is at the practical level, "△", many toner scattering The case where it was recognized and had a problem in practical use was marked with "x".

After repeatedly forming an image, the surface of the photoconductor immediately after being cleaned by the cleaning blade was visually observed, and the presence or absence of an adhered matter or a scratch on the surface of the photoconductor was judged. The evaluation is “good” when almost no deposits or scratches are observed, and “△” when there are some deposits or scratches but at a practical level, and practical when there are many deposits or scratches. When there was a problem with, it was marked as "x".

Durability of developer It is shown by the number of copies to obtain a clear image.

As can be understood from the results shown in Table 2, according to the developers 1 to 3 of the present invention, the triboelectrification property and the fluidity of the toner are good even under the high temperature and high humidity environmental conditions. In the above, the negative electrostatic latent image formed on the organic photoconductor by the magnetic brush development method can be well developed without fog or toner scattering, and the charge rise is good even after a pause, resulting in fog. In addition, it does not occur, and in the cleaning process, it can be satisfactorily cleaned by a cleaning blade with a simple structure, resulting in a clear image quality without fog or toner scattering, and a clear image even after long-term use. The resulting developer has good durability.

On the other hand, according to the comparative developer 1, since the inorganic fine particles D for comparison whose surface is treated with the amino group-containing silicone oil are used, the triboelectric chargeability of the toner is inferior, and as a result, the fog after rest is caused. It has a large amount of stains and low durability, resulting in an unclear image at an early stage.

Further, according to the comparative developer 2, since the inorganic fine particles E for comparison whose surface is treated with the amino group-containing silane coupling agent are used, the surface of the inorganic fine particles is completely covered with the amino group-containing silane coupling agent. It is difficult to cover the inner surface of the toner particles, so that the negatively chargeable sites and the hydrophilic sites of the inorganic fine particles remain, resulting in poor triboelectric chargeability of the toner, resulting in an image with a lot of fog and an unclear image.

[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

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yuya Masaki 2970 Ishikawa-cho, Hachioji-shi, Tokyo Konica Co., Ltd. (56) References JP-A-63-225247 (JP, A)

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. An image forming method, which is an electrostatic latent image developer formed by externally mixing inorganic fine particles formed by surface-treating polysiloxane containing a structural unit of 0.1 to 5% by weight with a toner. 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.