JPH03197965A - Developer - Google Patents

Abstract

PURPOSE:To stably form images free from black spots many times by using a developer for an org. photosensitive body contg. colored particles and combined fine particles obtd. by sticking specified inorg. fine particles to the surfaces of specified resin particles. CONSTITUTION:An electrostatic charge image formed by an image forming process on an org. photoconductive photosensitive body (photosensitive body) is developed with a developer contg. colored particles contg. a colorant and resin and combined fine particles obtd. by sticking inorg. fine particles having 0.01-1mum average particle size to the surfaces of resin particles having 10-500kg/cm<2> yield value at 20 deg.C and 0.1-7mum average particle size as nuclei. When the combined fine particles are put between a cleaning member and the photosensitive body and receive high pressing force, the resin particles are moderately deformed to relieve the intense rubbing action of the inorg. fine particles. Images free from black spots can stably be formed many times without causing the damage of the org. photosensitive body due to the inorg. fine particles.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention uses an organic photoconductive photoreceptor to form an image through the steps of forming an electrostatic image, developing, transferring, and cleaning. It relates to a developer used in an image forming process.

[Conventional technology]

In an example of electrophotography, an electrostatic image is formed on a photoconductor by charging and exposure, this electrostatic image is developed with a developer containing toner to form a toner image, and this toner image is then transferred. The image is transferred to a material and fused to form a visible image.

On the other hand, toner remaining on the photoreceptor without being transferred to the transfer material is cleaned by a cleaning member placed in pressure contact with the surface of the photoreceptor.

As a toner constituting a developer used in such an image forming process, a toner containing colored particles and composite fine particles made of resin particles whose surface is treated with inorganic fine particles has been proposed. (Unexamined Japanese Patent Publication No. 1983-
91143).

In the above publication, as the resin constituting the resin particles,
Acrylic polymers, acrylic/styrene polymers, polymers or copolymers of nitrogen-containing addition polymerizable monomers, polymers or copolymers of addition polymerizable carboxylic acids, fluororesins, and silicone resins are used. is listed.

[Problem to be solved by the invention]

However, in the toner disclosed in the above publication, the resin constituting the resin particles that serve as the core of the composite fine particles is hard and brittle, so it cannot be used in an image forming process using an organic photoconductive photoreceptor with a relatively soft surface as a photoreceptor. It has been found that there are the following problems when using it.

In order to improve the cleaning performance in the cleaning process, when cleaning is performed by placing a cleaning member in contact with the surface of the organic photoconductive photoreceptor with a relatively large pressure contact force, the contact between the cleaning member and the surface of the organic photoconductive photoreceptor is Since the composite fine particles sandwiched between them are subjected to a large pressure contact force, the inorganic fine particles present on the surface of the composite fine particles strongly rub the surface of the organic photoconductive photoreceptor, causing damage, and the toner constituent materials are removed in the damaged area. As a result, when the next image is formed, toner adheres to the embedded toner constituent materials and is fixed, resulting in black spot-like stains (black spots) on the image. There are problems that occur.

An object of the present invention is to provide a developer that can stably form images without black spots many times without causing poor cleaning due to composite fine particles.

[Means to solve the problem]

In order to achieve the above object, in the present invention, an electrostatic charge image is formed on an organic photoconductive photoreceptor (hereinafter referred to as "organic photoreceptor"), and this electrostatic charge image is developed with a developer. In a developer used in an image forming process that includes a step of forming a toner image and cleaning the toner remaining on an organic photoreceptor after transferring the toner image to a transfer material, the toner constituting the developer is colored particles containing at least a resin and a colorant, and a yield value of 1 at 20°C;
0-500 kg/cm2 with an average particle size of 0.1-7μm
A structure is adopted in which composite fine particles are formed by fixing inorganic fine particles having an average particle size of 0.01 to 1 μm on the surface of resin particles.

That is, in the present invention, by using resin particles whose yield value at 20° C. is within a specific range as the core of the composite fine particles, due to the tenacious physical properties of the resin particles, This prevents damage caused by inorganic fine particles adhered to the surface of the resin particles and prevents the occurrence of black spots.

To explain in detail, the resin particles that form the core of the composite fine particles are
Since the yield value at 20°C is within a specific range, the resin particles can be deformed without being destroyed by appropriately following the compression pressure when subjected to compression pressure at room temperature. It has strong physical properties.

Therefore, when cleaning residual toner with a cleaning member placed in contact with a soft organic photoreceptor with a relatively large pressure contact force, the composite fine particles are sandwiched between the cleaning member and the photoreceptor and are subjected to a large pressure contact force. In some cases, the resin particles are moderately deformed and exert a sonic action, which considerably alleviates the strong abrasion effect caused by inorganic particles, and produces images without black spots without damaging the organic photoreceptor due to inorganic particles. can be stably formed many times.

Hereinafter, the configuration of the present invention will be specifically explained.

The fine composite particles constituting the developer of the present invention have a yield value of 10 to 500 kg/cm at 20°C, preferably 20
~300 kg/cm” with an average particle size of 0.1-7μm
Preferably, the core is a resin particle of 0.2 to 5 μm, and inorganic fine particles with an average particle diameter of 0.01 to 1 μm, preferably 0.01 to 0.5 μm are fixed to the surface of the resin particle. .

Here, the yield value is JIS K 7113-1981
This refers to the value measured by the method specified in .

Yield value at 20℃ is 10-500 kg/cm'
The resin has a tenacious physical property that although it is moderately deformed by compression pressure at room temperature, it does not completely break or shatter.

On the other hand, when the yield value at 20°C of the resin constituting the resin particles is less than 1Q kg/cm2, the resin particles are greatly deformed even by a slight compression pressure, so the composite fine particles do not exhibit a good rolling effect. , the fluidity of the toner decreases, and the adhesion force to the organic photoreceptor increases, resulting in poor cleaning.

On the other hand, if the yield value at 20°C of the resin constituting the resin particles exceeds 500 kg/cm, the resin does not have sufficient tenacity, and the resin particles will deform when subjected to a large pressing force from the cleaning member. The abrasive action of the inorganic fine particles will be large, which will easily damage the surface of the organic photoreceptor, and the resin particles will rapidly break down, resulting in poor cleaning. black spots are likely to occur due to damage to the surface of the organic photoreceptor.

The average particle diameter of the resin particles constituting the composite fine particles is 0.1 to
The thickness is 7 μm, preferably 0.2 to 5 μm. Here, the average particle size of the resin particles is measured using a laser diffraction particle size distribution analyzer manufactured by SYMPATEC r)IELO3-CDI
, lPETlTl0N/3 J.

When the average particle size of the resin particles is within this range, the resin particles exhibit a good rolling effect, that is, the presence of composite fine particles of a suitable size between the colored particles provides a good lubricating effect. Therefore, the cleaning performance of the toner is improved.

On the other hand, when the average particle size of the resin particles is less than 0.1 μm, the cleaning performance tends to deteriorate because the rolling action of the composite fine particles becomes insufficient.

Conversely, when the average particle size of the resin particles exceeds 7 μm,
If the triboelectric charging properties of the toner tend to be inhibited, the image density tends to decrease.

The resin constituting the resin particles of the composite fine particles has a temperature of 20°C.
The resin is selected from resins having a yield value in the range of 10 to 500 kg/cm, preferably 20 to 300 kg/cm, and specifically, ethylene-vinyl acetate copolymer, polyurethane, vinylidene chloride resin, Vinyl chloride resin, ABS resin, etc. can be used.

The average particle size of the inorganic fine particles constituting the composite fine particles is 0.0
1 to 1 μm, preferably 0.01 to 0.5 μm
It is. Here, the average particle size of inorganic fine particles is the average particle size of primary particles, which is observed with a scanning electron microscope,
Refers to the number average particle diameter measured by image analysis.

When the average particle size of the inorganic fine particles is within this range, good cleaning properties are exhibited, and furthermore, a suitable polishing action is exhibited, and degraded or filming portions on the surface of the organic photoreceptor are effectively removed. The surface properties of the organophotoreceptor are maintained stably over a long period of time.

On the other hand, when the average particle size of the inorganic fine particles is less than 0.01 μm, they tend to be buried in the resin particles, resulting in insufficient cleaning performance. Conversely, if the average particle size of inorganic fine particles is 1
When it exceeds μm, it is difficult to adhere to the surface of the resin particles, and the surface of the organic photoreceptor is easily damaged by the free inorganic fine particles.

Inorganic materials that make up the inorganic fine particles include silicon oxide, aluminum oxide, titanium oxide, zinc oxide, zirconia oxide, chromium oxide, cerium oxide, tungsten oxide, antimony oxide, copper oxide, tin oxide, tellurium oxide, manganese oxide, Oxides such as boron oxide, barium titanate, aluminum titanate, magnesium titanate, calcium titanate, strontium titanate, ■ carbides such as silicon carbide, tungsten carbide, boron carbide, titanium carbide, ■ silicon nitride, titanium nitride, Nitride such as boron nitride, etc. can be used.

The composite fine particles are composed of the above inorganic fine particles fixed to the surface of the above resin particles. Here, adhesion refers to a state in which the inorganic fine particles are not simply attached to the resin particles by electrostatic force, but the length of the part of the inorganic fine particles embedded in the resin particles is 5 to 95%. Such a state can be confirmed by observing the surface of the composite fine particles using a transmission electron microscope or an ordinary electron microscope.

When fixing inorganic fine particles to the surface of resin particles,
It is preferable that the resin particles are first sphericalized and then the inorganic fine particles are fixed to the surface of the resin particles. This is because when the resin particles are spherical, the inorganic fine particles are evenly fixed, and separation of the inorganic fine particles is effectively prevented. On the other hand, if irregularly shaped resin particles are used, the inorganic fine particles will not adhere to the surface of the resin particles uniformly.
Inorganic fine particles become easily liberated. Moreover, the surface of the resin particles is largely exposed.

Methods for making resin particles spherical include: (1) melting the resin particles by heat and then performing spray granulation; (2)
Examples include a method in which heat-molten resin particles are jetted into water to make them spherical, and (2) a method in which spherical resin particles are synthesized by a suspension polymerization method or an emulsion polymerization method.

As a means of fixing inorganic fine particles to the surface of resin particles,
A method in which inorganic fine particles and resin particles are mixed and then heat is applied, a so-called mechanochemical method in which inorganic fine particles are mechanically fixed to the surface of resin particles, etc. can be used. Specifically, ■Resin particles and inorganic fine particles are mixed, stirred and mixed using a Henschel mixer V type mixer, turbular mixer, etc., the inorganic fine particles are attached to the surface of the resin particles by electrostatic force, and then the inorganic fine particles are attached to the surface of the resin particles. A method in which resin particles with fine particles attached are introduced into a heat treatment device such as a Niro atomizer or a spray dryer, and heat is applied to soften the surface of the resin particles and inorganic fine particles are fixed to the surface. ■Electrostatic force is applied to the surface of the resin particles. A device that can apply mechanical energy after depositing inorganic fine particles using a modified impact-type crusher, such as the Ongumi Nobe Free Mill,
A method of fixing inorganic fine particles to the surface of resin particles using a device such as a hybridizer can be adopted.

When obtaining composite fine particles, the amount of inorganic fine particles mixed with the resin particles may be any amount that can uniformly cover the surfaces of the resin particles. Specifically, it varies depending on the specific gravity of the non-molecular particles, but usually 5 to 60% by weight based on the resin particles.
The inorganic fine particles are preferably used in a proportion of 5 to 40% by weight. With such a ratio, the inorganic fine particles can be fixed sufficiently uniformly to the surface of the resin particles. On the other hand, if the proportion of inorganic fine particles is too small, the cleaning performance tends to deteriorate, and conversely, if the proportion of inorganic fine particles is too large, the inorganic fine particles tend to be liberated, resulting in a decrease in durability.

The above composite fine particles are added and mixed with colored particles to form a toner, and the blending ratio of the composite fine particles is preferably in the range of 0.01 to 2.0% by weight based on the colored particles. Within this range, fairly good leaning properties can be obtained, the triboelectric charging properties of the toner will not be inhibited, and good fluidity will be exhibited. On the other hand, when the blending ratio of composite fine particles is too small, cleaning performance tends to deteriorate. On the other hand, if the blending ratio of composite fine particles is too large, the triboelectric charging properties of the toner will be inhibited and the fluidity will decrease.
Image density tends to decrease.

The colored particles constituting the developer of the present invention are colored particles containing at least a resin and a colorant.

The average particle size of the colored particles is usually in the range of 1 to 30 μm.

As the resin constituting the colored particles, polyester resin,
Styrene resins, acrylic resins, styrene-acrylic copolymer resins, epoxy resins, etc. can be used.

Colorants that make up the colored particles include carbon black, nigrosine dye, aniline blue, calco oil blue, chrome yellow, ultramarine blue, DuPont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green offsalate, and lamp black. , Rose Bengal, etc. can be used.

The colored particles may contain other additives as necessary. Examples of such other additives include charge control agents, fixability improvers, and the like.

As the charge control agent, nigrosine dye or the like can be used.

As the fixing property improving agent, low molecular weight polyolefin or the like can be used.

Further, when obtaining a magnetic toner, magnetic particles are contained as an additive in the colored particles. As such magnetic particles, particles of ferrite, magnetite, etc. having an average particle size of 0.1 to 2 μm can be used. The amount of magnetic particles added is usually 20 to 70% by weight of the colored particles excluding external additives such as composite fine particles.

Further, in the present invention, inorganic fine particles may be added and mixed from the outside to the mixture of colored particles and composite fine particles to form a toner. These inorganic fine particles can further improve the fluidity of the toner. As such inorganic fine particles, in particular, silica fine particles whose surface has been treated with a hydrophobizing agent such as a silane coupling agent or a titanium coupling agent can be preferably used.

To give an example of a method for manufacturing the toner constituting the developer of the present invention, the resin constituting the colored particles, the colorant, and other additives used as necessary are mixed, melt-kneaded, and after cooling. It is crushed and classified to obtain colored particles with a desired average particle size. Next, the colored particles and composite fine particles are mixed using a device such as a Henschel mixer, and the composite fine particles are attached to the surface of the colored particles by electrostatic force to produce a toner.

The developer of the present invention may be a two-component developer composed of the above toner mixed with a carrier, or when the toner is a magnetic toner, a one-component developer composed only of the magnetic toner. It may be a type developer.

As the carrier constituting the two-component developer, a coated carrier in which the surfaces of magnetic particles are coated with a resin can be preferably used from the viewpoint of increasing the durability of the developer.

As such magnetic particles, particles of ferrite, magnetite, etc. can be used.

Further, as the coating resin, a fluororesin or the like can be used.

The average particle size of the carrier is usually in the range of 30 to 150 μm.

The developer of the present invention forms an electrostatic charge image on an organic photoreceptor,
This electrostatic charge image is developed with a developer to form a toner image, and after this toner image is transferred to a transfer material, it is used in an image forming process that includes a step of cleaning the toner remaining on the organic photoreceptor.

Each step will be specifically explained below.

(Electrostatic Image Forming Step) The surface of the organic photoreceptor is uniformly charged using a corona charger or the like, and then imagewise exposed using an exposure optical system to form an electrostatic image on the organic photoreceptor.

An organic photoreceptor is a photoreceptor constructed by laminating, for example, an organic photosensitive layer on a conductive support, in which an organic photoconductive substance is dispersed in a binder resin.

It is particularly preferable that such an organic photoreceptor has a laminated structure in which the organic photosensitive layer has a carrier generation layer and a carrier transport layer.

The carrier generation layer is a layer containing a carrier generation substance that generates charged carriers by absorbing visible light, and the carrier transport layer is a layer containing a carrier generation substance that generates charged carriers by absorbing visible light. This layer contains a carrier transport substance that transports. In such a laminated organic photosensitive layer having a carrier generation layer and a carrier transport layer, two basic functions necessary for the photosensitive layer, namely generation of carriers and transport thereof, are assigned to separate layers. Therefore, the selection range of materials that can be used to construct the photosensitive layer is widened, and it is also possible to independently select materials or material systems that optimally perform each function.
As a result, it has excellent characteristics required in the image forming process, such as high surface potential when charged, high charge retention capacity, high photosensitivity, and high stability during repeated use. It becomes possible to construct an organic photoreceptor.

As the carrier-generating substance, for example, Anse Anse One type pigments, perylene derivatives, phthalocyanine type pigments, bisazo type pigments, indigoid type pigments, etc. can be used.

As the carrier transport substance, for example, carbazole derivatives, oxadiazole derivatives, triarylamine derivatives, polyarylalkane derivatives, hydrazone derivatives, pyrazoline derivatives, stilbene derivatives, styryltriarylamine derivatives, etc. can be used.

The thickness of the carrier generation layer is usually 0.01 to 2 μm, and the thickness of the carrier transport layer is usually 1 to 30 μm.

Binder resins include polycarbonate resin, vinyl acetate resin, epoxy resin, polyurethane resin, polyester resin, polyurethane resin, methacrylic resin, acrylic resin, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyvinyl acetate, and styrene-butadiene copolymer. , vinylidene chloride-acrylonitrile copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone-alkyd resin, phenol-formaldehyde resin, styrene-alkyd resin, polymer 1J-N-vinylcarbazole and the like can be used.

Specific examples of the structure of the organic photoreceptor are shown in FIGS. 1 to 6.

1 and 3 each show an example in which an organic photosensitive layer 14 made of a laminate of a carrier generation layer 12 and a carrier transport layer 13 is provided on a conductive support 11.

FIGS. 2 and 4 each show an example in which an intermediate layer 15 is further provided between the organic photosensitive layer 14 and the conductive support 11 having the above structure.

FIG. 5 shows an example in which an organic photosensitive layer 14 in which a carrier generating substance 17 is dispersed and contained in a layer 16 mainly composed of a carrier transporting substance is provided on a conductive support 11. This is an example in which an intermediate layer 15 is further provided between the organic photosensitive layer 14 and the conductive support 11.

Examples of the conductive support constituting the organic photoreceptor include metal plates or metal drums made of aluminum, nickel, copper, zinc, palladium, silver, indium, tin, platinum, gold, stainless steel, steel, brass, alloys, etc. Aluminum,
A conductive-treated sheet obtained by laminating conductive materials such as palladium, gold, alloys, and indium oxide by means such as coating, vapor deposition, and lamination can be used.

The intermediate layer has a function as an adhesive layer or a barrier layer, and its constituent materials include the same resin as above used as a binder resin for the organic photosensitive layer, and metals such as aluminum oxide and indium oxide. Oxides can be used.

(Developing Step) The developer of the present invention is transported to a developing area by a developer transporting carrier, and the electrostatic charge image formed on the surface of the organic photoreceptor is developed in the developing area.

The developer transport carrier preferably has a structure to which a bias voltage can be applied, such as a cylindrical sleeve on which a developer layer is supported, and a magnet body having a plurality of magnetic poles arranged inside the sleeve. It is possible to use one configured by: The rotation of the sleeve and/or the magnet conveys the developer layer on the sleeve to the development area.

In order to convey a developer layer having a uniform thickness to the development area, it is preferable to provide a thickness regulating member on the upstream side of the development area on the developer transport carrier.

As the bias voltage applied to the developing sleeve, a DC voltage or a voltage obtained by superimposing an AC voltage on a DC voltage can be used.

(Transfer step) The toner image on the organic photoreceptor obtained by development is transferred to a transfer material such as paper.

In this transfer step, an electrostatic transfer method can be preferably used. Specifically, for example, a transfer device that generates a DC corona discharge is placed so as to face the organic photoreceptor through the transfer material, and the DC corona discharge is applied to the transfer material from the back side of the organic photoreceptor. The toner carried on the surface is transferred to the surface of the transfer material.

(Cleaning process) Using a cleaning device equipped with a cleaning member such as a cleaning blade placed in pressure contact with the organic photoreceptor,
Cleans toner remaining on the organic photoreceptor without being transferred.

The pressing force of the cleaning member against the organic photoreceptor is preferably 5 to 50 g/cm from the viewpoint of improving cleaning performance.

Note that, before this cleaning step, it is preferable to add a charge removal step for removing charge from the surface of the organic photoreceptor in order to facilitate cleaning.

This static elimination step can be performed, for example, using a static eliminator that generates AC corona discharge.

(Fixing Step) In the transfer step, the transfer material onto which the toner image has been transferred is subjected to a fixing process using a fixing device such as a heat roller fixing device, thereby forming a fixed image.

FIG. 7 is an explanatory diagram showing an example of an image forming apparatus that can perform the above image forming process. In the same figure, 10
is an organic photoreceptor, 21 is a charger, 22 is an exposure optical system, 23
is a developing device, 24 is a static elimination lamp, 25 is a transfer electrode, 26
27 is a separation electrode, 27 is a static elimination electrode, 28 is a cleaning device, 29 is a heat roller fixing device, 30 is a cleaning blade, and 40 is a document table. This apparatus is of a type in which the exposure optical system 22 is fixedly arranged and the document table 40 is moved.

The surface of the organic photoreceptor 10 is uniformly charged by the charger 21, and the charged surface of the organic photoreceptor 10 is exposed imagewise by the exposure optical system 22, so that an electrostatic charge corresponding to the original is deposited on the organic photoreceptor 10. An image is formed. This electrostatic charge image is developed by a developing device 23 to form a toner image.

After this toner image is neutralized by the static elimination lamp 24 and made easily transferable, it is transferred onto the transfer paper P by the transfer electrode 25. The transfer paper P is separated from the organic photoreceptor 10 by the separation electrode 26 and subjected to a fixing process by a heat roller fixing device 29, thereby forming a fixed image. On the other hand, static electricity is removed from the organic photoreceptor 10 by a static elimination electrode 27, and toner remaining on the organic photoreceptor 10 without being transferred is scraped off by a cleaning device 28.

The cleaning blade 30 is made of an elastic material such as hard urethane rubber with a thickness of 1 to 3 mm, and has a length substantially corresponding to the width of the organic photoreceptor 10 (in the direction perpendicular to the plane of the paper in FIG. 7). It is held by a blade holder (not shown) so as to be switchable between a pressure contact position and a pressure release position.

〔Example〕

Examples of the present invention will be described below along with comparative examples, but the embodiments of the present invention are not limited to these Examples. Note that "parts" represent "parts by weight."

<Resin particles constituting the composite particles> (1) Resin particles A (for the present invention) Made of ethylene-vinyl acetate copolymer (ethylene:vinyl acetate-8:2), with a yield value of 135k at 20°C
Resin particles with an average particle size of 3.0 μm in g/cm2.

(2) Resin particles B (for the present invention) are made of ethylene-vinyl acetate copolymer (ethylene; vinyl acetate = 8:2) and have a yield value of 135k at 20°C.
Resin particles with an average particle size of 0.20 t, t m in g/cm2.

(3) Resin particles C (for the present invention) are made of polyurethane and have a yield value of 300 at 20°C.
kg/cm" and an average particle size of 1.0 μm.

(4) Resin particles a (for comparison) Resin particles with an average particle size of 1.0 μm, made of an acrylic polymer, and have no yield value and are easy to break.

(5) Resin particle b (for comparison) Made of styrene-acrylonitrile copolymer, 20℃
The yield value is 700 kg/cm" and the average grain size is 0.
5 μm resin particles.

Inorganic fine particles constituting composite fine particles> (1) Inorganic fine particles A (for the present invention) Inorganic fine particles made of titanium oxide and having an average particle size of 0.2 μm.

(2) Inorganic fine particles B (for the present invention) Inorganic fine particles made of silicon carbide and having an average particle size of 0.05 μm.

<Manufacture of composite fine particles> Resin particles and inorganic fine particles in the combinations and amounts shown in Table 1 below are sufficiently stirred and mixed using a V-type mixer, and the inorganic fine particles are attached to the surface of the resin particles by electrostatic force. After that, this mixture was charged into an improved conventional impact-type pulverizer, and an impact force was applied to the mixture to produce composite fine particles in which inorganic fine particles were fixed to the surface of resin particles.

Surface observation using an electron microscope and transmission electron microscope revealed that the inorganic fine particles that had been attached to the surface of the resin particles by electrostatic force were embedded and held in the surface of the resin particles. It was recognized that

Table 1 <Example 1> Polyester resin 100 parts Carbon black 10 parts Unbalanced molecular weight polypropylene 5 parts or more of substances were mixed, kneaded, crushed, and classified to produce non-magnetic colored particles 1 with an average particle size of 12.0 μm. I got it.

To the colored particles 1, 0.4% by weight of hydrophobic silica fine particles "Aerosil R-972J" manufactured by Nippon Aerosil Co., Ltd. and 0.6% by weight of the composite fine particles were added, and mixed with a Henschel mixer to form a toner. 1 was manufactured.

A two-component developer A according to the present invention is produced by mixing 5 parts of this toner 1 and 95 parts of a coating carrier having an average particle diameter of 80 μm, which is made by coating the surface of ferrite particles with a fluororesin. did.

<Example 2> In Example 1, composite fine particles A were mixed with 0 of composite fine particles B.
．． A two-component developer B according to the present invention was produced in the same manner except that the amount was changed to 3% by weight.

<Example 3> Polyester resin 55 parts Magnetite 40 parts Unbalanced molecular weight polypropylene 3 parts Nigrosine dye (charge control agent) 2 parts or more of the substance was treated in the same manner as in Example 1 to form a magnetic colored material with an average particle size of 11.0 μm. Particles 2 were obtained.

Hydrophobic silica fine particles "Aerosil R-972J" manufactured by Nippon Aerosil Co., Ltd. are added to the colored particles 2 in a ratio of 0.4% by weight and composite fine particles B are added in a proportion of 0.4% by weight, and mixed with a Henschel mixer to form the magnetic toner 2. This magnetic toner 2 alone constituted a one-component developer C according to the present invention.

<Example 4> In Example 3, composite fine particles B were mixed with 1 of composite fine particles C.
．． A one-component developer according to the present invention was produced in the same manner except that the amount was changed to 2% by weight.

Comparative Example 1 A comparative two-component developer a was produced in the same manner as in Example 1, except that the amount of composite fine particles A was changed to 0.6% by weight of the comparative fine composite particles a. .

Comparative Example 2 A comparative one-component developer was produced in the same manner as in Example 3, except that the compound fine particles B was changed to 0.4% by weight of the comparative composite fine particles. did.

<Manufacture of a dim light material> Based on the configuration shown in Figure 1, a carrier generation layer containing 4.10-dibromoanthurone as a carrier generation substance and a styryltriphenylamine compound as a carrier transport substance An organic photoreceptor was manufactured by laminating a negatively chargeable photosensitive layer having a two-layer structure including a carrier transport layer containing the following components on a rotating drum-shaped aluminum conductive support.

This is made into an organic photoreceptor.

(Image formation test) Using each developer obtained as above,
The electrostatic charge image formed on the organic photoreceptor is developed to form a toner image, this toner image is transferred to a transfer material, the transferred toner image is fixed, and the toner remaining on the organic photoreceptor is cleaned after transfer. A test was conducted in which a copy image was formed by performing an image forming process including a cleaning step with a blade.

Note that developers A, B, and a, which are two-component developers, are connected to the organic photoreceptor by a two-component developer equipped with a developing device for two-component developers and a cleaning blade. Electrophotocopy machine U-Bix 180 manufactured by Konica ■
Using a modified machine, a test was conducted in which copy images were formed up to 100,000 times under environmental conditions of a temperature of 20° C. and a relative humidity of 55%.

Developers C, D, and b, which are -component developers, are one-component developers that include the organic photoreceptor A, a non-contact developing device that applies an oscillating electric field to the development area, and a cleaning blade. Using a prototype electrophotographic copying machine for developer, a maximum of 1.
A test was conducted in which a copy image was formed 00,000 times.

Through the above tests, the following items were evaluated. The results are shown in Table 2 below.

■Cleanability Immediately after cleaning with the cleaning blade, the surface of the organic photoreceptor is visually observed to check for the presence of deposits.If there is almost no deposit observed, the rating is "O", and if the deposit is slightly reduced in diameter, If it is at a practical level, "Δ"
, Cases where there was a large amount of deposits and were problematic in practice were marked as "x".

(2) Damage to Photoreceptor The surface of the organic photoreceptor was visually observed to check for damage. Note that the observation was made after the live-action test was completed.

■ Visually observe the black spot copy image to check for the presence of black spots caused by damage to the surface of the organic photoreceptor. If there are almost no black spots, it is marked as "○". A case where it is at a practical level is marked as "△", and a case where there are many black spots and there is a problem in practical use is marked as rXJ.

As is clear from Table 2 above, the developer A-
According to D, the surface of the organic photoreceptor can always be maintained in a good condition, and good leaning properties can be exhibited.

Furthermore, no black spots due to damage to the surface of the organic photoreceptor were observed.

On the other hand, in the comparative developers a and b, since the resin particles constituting the composite fine particles are hard, the inorganic fine particles on the surface of the composite fine particles sandwiched between the cleaning blade and the organic photoreceptor The surface of the organic photoreceptor was damaged from the beginning, resulting in poor cleaning performance.

〔Effect of the invention〕

As explained in detail above, according to the developer of the present invention,
The resin particles that form the core of the composite fine particles have a yield value within a specific range at 20°C and have strong physical properties, so they can be placed in contact with the organic photoreceptor with a relatively large pressing force, or they can be placed in contact with the organic photoreceptor or used as an IJ or = contact member. Even when the composite fine particles sandwiched between the cleaning member and the organic photoreceptor are subjected to a large pressure force when cleaning toner, the resin particles that constitute the core of the composite fine particles are appropriately deformed and create a cushion. There is no risk that the surface of the organic photoreceptor will be strongly abraded by the inorganic fine particles present on the surface of the composite fine particles, and damage to the surface of the organic photoreceptor can be effectively prevented, leading to poor cleaning. Images without black spots can be stably formed many times without any trouble.

[Brief explanation of drawings]

1 to 6 are sectional views showing specific examples of the structure of an organic photoreceptor, and FIG. 7 is a schematic view showing an example of an image forming apparatus. DESCRIPTION OF SYMBOLS 10... Organic photoreceptor 11... Conductive support 12... Carrier generation layer 13... Carrier transport layer 14... Organic photosensitive layer 15... Intermediate layer 16
...Layer mainly composed of a carrier transporting substance 17...Carrier generating substance 21...Charging device 22...Exposure optical system 23...Developing device 24...Static elimination lamp
25... Transfer electrode 26... Separation electrode
27... Static elimination electrode 28... Cleaning device 29
...Heat roller fixing device 30...Cleaning blade 40...Original plate diagram (10) + 3 (14) 15 (15) 16

Claims (1)

[Scope of Claims] An electrostatic charge image is formed on an organic photoconductive photoreceptor, this electrostatic charge image is developed with a developer to form a toner image, and after this toner image is transferred to a transfer material, an organic In a developer used in an image forming process including a step of cleaning toner remaining on a photoconductive photoreceptor, the toner constituting the developer contains colored particles containing at least a resin and a colorant; Yield value at ℃ is 10
~500 kg/cm^2, containing composite fine particles in which inorganic fine particles with an average particle size of 0.01 to 1 μm are fixed to the surface of resin particles with an average particle size of 0.1 to 7 μm. Characteristic developer.