JPH08286428A - Color electrophotographic developer and color image forming method using same - Google Patents

Abstract

PURPOSE: To form a stable color image over a long period of time without darkening the color even when a magnetic substance is scraped from the carrier component of a developer and enters into the developer by producing magnetic substance dispersed carriers with magnetic substances whose colors corresponds to the colors of toners, respectively. CONSTITUTION: A yellow developer is composed of a toner contg. a yellow coloring material and a bonding resin and a magnetic substance dispersed carrier contg. a bonding resin and a yellow magnetic substance. A magenta developer is composed of a toner contg. a magenta coloring material and a bonding resin and a magnetic substance dispersed carrier contg. a bonding resin and a magenta magnetic substance. A cyan developer is composed of a toner contg. a cyan coloring material and a bonding resin and a magnetic substance dispersed carrier contg. a bonding resin and a cyan magnetic substance. A black developer is composed of a toner contg. a black coloring material and a bonding resin and a magnetic substance dispersed carrier contg. a bonding resin and a black magnetic substance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-component color developer and an image forming method using the same.

[0002]

2. Description of the Related Art Recently, electrophotographic copying products have shifted from monochrome to full color. Accordingly, development of better magenta, cyan, yellow and black developers has been demanded. At present, as the developer, a two-component developer composed of a carrier and a toner of any one of the colors is generally used.

Most of the carriers here are of the type in which a magnetic substance is dispersed in a binder resin (magnetic substance-dispersed type carrier), and the use of a two-component type developer composed of this carrier and toner. For example, in the magnetic substance dispersion type carrier, since the magnetic brush (brushing at the time of development) is densely formed, the gradation is good, the solid image is uniform, and the image quality is good.
The carrier has the advantages of being lightweight, preventing the deterioration of the developer, and extending the life of the developer. However, when such a magnetic substance-dispersed carrier is used for a color developer, the binder resin is scraped off over a long period of time, and the magnetic substance is peeled off. Therefore, since this magnetic material is black, the latent image is developed together with the toner during development. Therefore, if the developed color is, for example, yellow, magenta, or cyan, the color of each of these colors becomes dull due to the magnetic substance (it is not bright or becomes blackish), and it may not be possible to obtain a high-quality color image.

In order to prevent such inconveniences from occurring, (1) the binder resin for each of the carrier particles and the toner particles is specified, and the amount of the magnetic fine powder in the carrier particles is specified (Japanese Patent Laid-Open No. SHO 61-96). 59-97154), and (2) Pigment Red 112 as a colorant, which has a fourth surface.
A positively chargeable toner having silica fine particles treated with an ammonium salt or an aminosilane coupling agent attached thereto is used (JP-A-6-242634), and (3) a magnetic substance-dispersed carrier containing a vinylidene fluoride copolymer is used. Used (JP-A-2-188864), (4) A magnetic substance-dispersed carrier provided with a surface layer of a fluorinated alkyl acrylic copolymer (JP-A-2-157854, JP-A-2-157854).
No. 184866) has been proposed.

[0005]

However, in spite of these proposals, when the two-component type developer is used, it is the actual situation that a good quality color or full-color copy is not obtained. Therefore, an object of the present invention is to provide a two-component developer suitable for obtaining a good quality color copy (including a full color copy), and a color image forming method using the developer.

[0006]

Means for Solving the Problems The inventors of the present invention prepared a magnetic substance dispersion type carrier of each color with a magnetic substance of a color corresponding to each toner color system and used it, whereby the magnetic substance was scraped from the carrier component. It has been found that even if mixed in the developer, the color does not become dull and a stable color image can be obtained for a long period of time. In addition, it is desirable to specify the toner and carrier particle size in order to achieve high image quality. Furthermore, the binder resin of the carrier particle contains silicone resin as the main component, and the magnetic substance is a silane coupling agent to prevent toner adhesion. It was also found that peeling is prevented when the surface is treated with. The present invention has been made based on these findings.

Therefore, according to the present invention, (1) the yellow developer is a toner containing at least a yellow colorant and a binder resin, and a magnetic material dispersion type carrier containing at least a binder resin and a yellow magnetic material. The magenta developer is composed of a toner containing at least a magenta colorant and a binder resin, a magnetic substance dispersion type carrier containing at least a binder resin and a magenta magnetic substance, and a cyan developer is at least a cyan colorant. And a toner containing a binder resin and a magnetic substance-dispersed carrier containing at least a binder resin and a cyan magnetic substance, and the black developer is at least a toner containing a black colorant and a binder resin. A color electron comprising a magnetic substance-dispersed carrier containing a binder resin and a black magnetic substance. True developer, (2) In the above (1), the particle size of the toner particles is in the range of 3.0 to 8.5 μm, and a developer for color electrophotography, (3) In the above (1) The particle size of the magnetic substance-dispersed carrier particles is 1
Color electrophotographic developer characterized by being in the range of 0 to 55 μm, (4) In (1) or (3), the binder resin of the magnetic substance-dispersed carrier particles contains a silicone resin as a main component. (5) The developer for color electrophotography according to (5), wherein the magnetic substance-dispersed carrier particles in the above (1), (3) or (4) contains a silane coupling agent or has a magnetic property in the carrier particles. There is provided a color electrophotographic developer, wherein the body is surface-treated with a silane coupling agent.

According to the present invention, (6) a first electrostatic latent image is formed on the image carrier, developed with color developer A, and then the color toner is transferred to a transfer member, Next, a second electrostatic latent image is formed on the image bearing member, and this is developed with a color developer B, and then the color toner is transferred and transferred onto the transfer member, and then on the image bearing member. After forming a third electrostatic latent image and developing it with color developer C, the color toner is transferred onto the transfer member in an overlapping manner, and a fourth electrostatic latent image is formed on the image carrier. A color image forming method in which the color toner is developed with a color developer D, the color toner is transferred onto the transfer member, and then the color toner on the transfer member is fixed. , C and D, the different yellow developers of (1), (2), (3), (4), and (5), A color image forming method characterized by using a zenta developer, a cyan developer, and a black developer, (7) forming a first electrostatic latent image on an image carrier, and using the color developer A After development, the color toner is transferred to an intermediate transfer member and then a second image is formed on the image carrier.
Electrostatic latent image is formed on the image carrier, and then the color toner is transferred to the intermediate transfer member, and then a third electrostatic latent image is formed on the image carrier. After developing this with color developer C, the color toner is transferred to the intermediate transfer member, and a fourth electrostatic latent image is formed on the image carrier, and this is developed with color developer D. After that, the color toner is transferred to the intermediate transfer member, the toner images transferred and transferred onto the member are transferred to another transfer member, and then the color toner is fixed.
As the developers A, B, C and D, the above (1) and (2)
(3) (4) There is provided a color image forming method characterized by using different yellow developers, magenta developers, cyan developers and black developers of (5).

The present invention will be described in more detail below. The developers A, B, C, and D of the present invention are all two-component developers composed of a carrier and a toner. If the developer A is, for example, a yellow developer, the toner is at least a binder resin. And a yellow coloring material, and the carrier (magnetic material dispersion type carrier) is composed of at least a binder resin and a yellow magnetic material of the same color as the toner. Therefore,
If the developer B is, for example, a magenta developer, the toner is composed of at least a binder resin and a magenta colorant, and the magnetic material dispersion type carrier is composed of at least a binder resin and a magenta magnetic material. The relationship between the carrier and the toner is the same in the cyan developer and the black developer.

The color image forming method of the present invention forms an electrostatic latent image on a photoconductor (image carrier) for each color using these two-component developers A, B, C and D. Developed,
This toner image is transferred onto the transfer member in an overlapping manner, and then the transferred toner image is fixed, or (2) an electrostatic latent image is formed on the photoconductor for each color, and this is developed, A means is employed in which the image is transferred onto the intermediate transfer member in an overlapping manner, and then the transferred toner image is transferred onto another member at a time and fixed.

The constituent materials of the toner and carrier used in the present invention are as follows. 1. Toner Structure (1) Specific Examples of Binder Resin Polystyrene, chloropolystyrene, poly-α-methylstyrene, styrene-chlorostyrene copolymer, styrene-propylene copolymer, styrene-butadiene copolymer, styrene-vinyl chloride copolymer Polymer, styrene-vinyl acetate copolymer, styrene-maleic acid copolymer, styrene-acrylic acid ester copolymer (styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-acrylic acid Butyl copolymer, styrene-
Octyl acrylate copolymer, styrene-phenyl acrylate copolymer, etc.), styrene-methacrylic acid ester copolymer (styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate) Copolymers, styrene-phenyl methacrylate copolymers, etc.), styrene-α-chloromethyl acrylate copolymers, styrene-acrylonitrile-acrylic acid ester copolymers and other styrene resins (including styrene or styrene substitutes) Homopolymer or copolymer), vinyl chloride resin, rosin-modified maleic acid resin, phenol resin, epoxy resin, polyester resin, low molecular weight polyethylene, low molecular weight polypropylene, ionomer resin,
Polyurethane resin, ketone resin, ethylene-ethyl acrylate copolymer, xylene resin, polyvinyl butyral, etc.

(2) Specific examples of yellow colorant CI Pigment Yellow 1 Symuler Fast Yellow GH
(Manufactured by Dainippon Ink) CI Pigment Yellow 3 Symuler Fast Yellow 10GH
(Made by Dainippon Ink) CI Pigment Yellow 12 Symuler Fast Yellow GF
(Manufactured by Dainippon Ink) CI Pigment Yellow 13 Symuler Fast Yellow GRF
(Manufactured by Dainippon Ink) CI Pigment Yellow 14 Symuler Fast Yellow 5GR
(Manufactured by Dainippon Ink) CI Pigment Yellow 17 Symuler Fast Yellow 8GR
(Manufactured by Dainippon Ink) Further, CI Pigment Yellow 12 includes the following. Yellow 152 (manufactured by Arimoto Kagaku) Pigment Yellow GRT (manufactured by Sanyo Dye) Sumika Print Yellow ST-O (manufactured by Sumitomo Chemical) Benzidine Yellow 1316 (manufactured by Noma Chemical) Seika Fast Yellow 2300 (manufactured by Dainichiseika) Rionol Yellow GRT ( (Made by Toyo Ink)

(3) Specific examples of magenta colorants CI Pigment Red 81 Symulex Rhodamine Y Toner F (manufactured by Dainippon Ink) CI Pigment Red 122 Fastogen Super Magenta R (manufactured by Dainippon Ink) CI Pigment Red 57 Symuler Brill Carmine LB ( CI Pigment Red 22 Symuler Fast Brill Scarlet BG (manufactured by Dainippon Ink) CI Pigment Red 21 Sanyo Fast Red GR (manufactured by Sanyo Dye) CI Pigment Red 18 Sanyo Toluidine Maroon Medium (manufactured by Sanyo Dye) CI Pigment Red 114 Symuler Fast Carmine BS (made by Dainippon Ink) CI Pigment Red 112 Symuler Fast Red FGR (made by Dainippon Ink) CI Pigment Red 5 Symuler Fast Carmine FB (made by Dainippon Ink)

CI Pigment Blue 15 Fastogen Blue GS (manufactured by Dainippon Ink) CI Pigment Blue 15 Chromofine SR (manufactured by Dainichiseika) CI Pigment Blue 16 Sumitone Cyanine Blue LG (manufactured by Sumitomo Chemical) CI Pigment Green 7 Phthalocyanine Green (Tokyo Ink) CI Pigment Green 36 Cyanine Green 2YL (Toyo Ink) CI Pigment Blue 15: 3 Cyanine Blue GGK (Nippon Pigment)

Specific Examples of Coloring Material for Black Carbon Black Spirit Black Aniline Black (C.I. Pigment Black 1)

The amount of the coloring material is appropriately 0.1 to 15 parts by weight, more preferably 0.1 to 9 parts by weight, based on 100 parts by weight of the binder resin. The above binder resins may be used alone or as a mixture of two or more kinds. Further, the coloring material is not limited to a single color, and two or more kinds may be used in combination so long as they are of the same color.

A charge control agent is generally added to the toner. As the charge control agent, a nigrosine dye, a chromium-containing complex, a quaternary ammonium salt or the like is used, and these are properly used depending on the polarity of the toner particles. In the case of a color toner, a colorless or pale color toner that does not affect the color tone of the toner is preferable, and examples thereof include a metal salt of salicylic acid or a metal salt of a salicylic acid derivative (Bontron E84, manufactured by Orient Co., Ltd.). The amount of charge control agent is 100
The amount is 0.1 to 10 parts by weight, and more preferably 0.2 to 7 parts by weight.

A fluidity imparting agent may be added to the toner particles in the present invention. As the fluidity-imparting agent, silica,
Fine particles of metal oxides such as alumina, magnesia, zirconia, ferrite, and magnetite, and silane coupling agents, titanate coupling agents, zircoaluminates, quaternized ammonium salts, fatty acids, fatty acid metal salts, fluorine-based activators , Surface-treated or coated with a treatment agent such as a solvent or polymer, stearic acid,
Fine particles of a fatty acid such as zinc stearate or a metal salt thereof, and those obtained by surface-treating the fine particles with the above-mentioned treating agent, polymer fine particles such as polystyrene, polymethylmethacrylate, and polyvinylidene fluoride, and surface treatment of the fine particles with the treating agent. Alternatively, a coated product is used. The average particle size of these fluidity-imparting agents is 0.01 to 3 μm.
Those in the range of are used. The amount of the fluidity-imparting agent added is 0.1 to 7.0 with respect to 100 parts by weight of the toner particles.
Weight part, especially 0.2-5.0 weight part is preferable.
The mixing method of the toner particles and the fluidity-imparting agent is such that the powder is moved in a fluidized state at a high speed by an air flow or mechanical force so as not to substantially pulverize. As the mixer, a high-speed flow type mixer, for example, Henschel mixer, UM
For example, a mixer.

As the method for producing the toner according to the present invention, various known methods or a combination thereof can be used. For example, in the kneading-grinding method, a binder resin, a coloring material such as carbon black, and necessary additives are dry-mixed, and the mixture is heated and melted and kneaded by an extruder, a two-roll roll, a three-roll roll, or the like, and solidified by cooling. After that, the toner is obtained by pulverizing with a pulverizer such as a jet mill and classifying with an air stream classifier. It is also possible to directly produce a toner from a monomer, a coloring material and an additive by a suspension polymerization method or a non-aqueous dispersion polymerization method.

The toner particles are measured by COULTER. C
OUNTER. MODEL. _A T _A II type (manufactured by Beckman Coulter, Inc.) is used to connect an interface for outputting the number distribution and the volume distribution to use an aperture (pore) of 100 μm. First, a toner measurement sample is dispersed in a surfactant added to an electrolytic aqueous solution. The sample is replaced with another 1% NaCl
It is injected into the electrolytic solution, and a current is passed between both electrodes through the electrolytic solution in which electrodes are placed on both sides of the aperture of the aperture tube, and the particle size distribution of particles of 2 to 40 μm is measured from this resistance change, and the volume is measured. The volume average particle size is obtained from the average distribution.

The toner particles have a particle size of 3.0 to 8.5 μm, preferably 3.5 to 8.0 μm. Particle size is 8.
If it is larger than 5 μm, dot reproducibility is poor in a digital copying machine. In addition, smooth gradation cannot be obtained. In particular, when a color pattern / painting original is copied, the graininess of the highlight portion is not good and the image quality is poor. On the other hand, when the particle size of the toner particles is smaller than 3.0, the toner particles are likely to adhere to the surface of the carrier and the Q / M value is lowered. Further, the scattered toner may be mixed with other developers, and as a result, the colors of the other developers may be contaminated, resulting in poor image quality.

2. Carrier Structure (1) Specific Examples of Binder Resin Polystyrene, chloropolystyrene, poly-α-methylstyrene, styrene-chlorostyrene copolymer, styrene-propylene copolymer, styrene-butadiene copolymer, styrene-vinyl chloride copolymer Polymer, styrene-vinyl acetate copolymer, styrene-maleic acid copolymer, styrene-acrylic acid ester copolymer (styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-acrylic acid Butyl copolymer, styrene-
Octyl acrylate copolymer, styrene-phenyl acrylate copolymer, etc.), styrene-methacrylic acid ester copolymer (styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate) Copolymers, styrene-phenyl methacrylate copolymers, etc.), styrene-α-chloromethyl acrylate copolymers, styrene-acrylonitrile-acrylic acid ester copolymers and other styrene resins (including styrene or styrene substitutes) Homopolymer or copolymer), vinyl chloride resin, rosin-modified maleic acid resin, phenol resin, epoxy resin, polyester resin, low molecular weight polyethylene, low molecular weight polypropylene, ionomer resin,
Polyurethane resin, ketone resin, ethylene-ethyl acrylate copolymer, xylene resin, polyvinyl butyral, silicone resin (Tore Dow Corning F
200, F250, F300, R900, R902, R
925, E500, E600, SH6018, DC6-
2230, Shin-Etsu Chemical KR271, KR255, K
R251, SR2400, SR2 made by Torre Silicone
406), modified silicone resin (KR2 made by Shin-Etsu Chemical Co., Ltd.
06 (alkyd resin modified product), KR3093 (acrylic resin modified product), ES1001N (epoxy resin modified product), Torre Silicone SR2115 (epoxy resin modified product), SR2110 (alkyd resin modified product))
etc.

(2) Specific examples of magnetic material 1. Yellow type YELLOW48 (made by Toda Kogyo Co., Ltd.) HY-100 (made by Titanium Kogyo Co., Ltd.) HY-200 (made by Titanium Kogyo Co., Ltd.) Y-2, E-401 (made by Toda Kogyo Co., Ltd.) 1. Magenta type 100ED, 120ED, 130ED, 140ED, 1
60ED, 180ED, 190ED, EC-101, E
C-131, EC-181 (manufactured by Toda Kogyo Co., Ltd.) 3. Cyan blue, EC-501 (manufactured by Toda Kogyo Co., Ltd.) 4. Black system KN-320, KH-340H, MS-350, HR-
340H, HR-370H, EC-301, EPT-1
000 (manufactured by Toda Kogyo Co., Ltd.), BL-SP, RB-BL (manufactured by Titanium Kogyo Co., Ltd.) In addition to yellow, magenta and cyan magnetic fine powders, all magnetically sensitive materials can be mentioned. For example, metals such as iron, nickel, and cobalt, metal oxides, alloys, and the like. Materials often used include ferrosoferric oxide, ferric sesquioxide, iron oxide containing cobalt, ferrite, and nickel fine powder. The amount of the magnetic substance is preferably 35 to 85 parts by weight, more preferably 50 to 80 parts by weight, based on 100 parts by weight of the binder resin.

The carrier may contain a conductivity control agent and / or a charge control agent as components other than the above. As the conductivity adjusting agent, known materials can be used, and examples thereof include conductive powders such as carbon black, aluminum powder, and silver powder. These conductive powders can also cause the magnetic fine powder to serve as a conductivity adjusting agent. On the other hand, known charge control agents can be used, for example, nigrosine dyes, quaternary ammonium salts, basic dyes (methylene violet, Victoria blue, etc.), phthalocyanines, silane coupling agents, salicylic acid derivatives, etc. , A dye containing a transition metal such as copper or chromium, and the like.

The carrier resistance preferably has a specific resistance of about 10 ⁸ to 10 ¹⁴ Ωcm when a DC voltage of 500 V / cm is applied. The carrier particle size is preferably 10 to 55 μm, more preferably 15 to 50 μm. When the particle diameter is 10 μm or less, carrier scattering becomes remarkable, and carrier adhesion easily occurs on a copy or a latent image carrier. Further, the fluidity as a developer becomes unstable, the toner density cannot be stably controlled during use, and it becomes difficult to obtain a toner having a constant image density. If the carrier particle size is 55 μm or more, the solid uniformity is poor and the solid part is scratched by the carrier, or when a color original such as a pattern or painting is copied, the leading edge of the image (copy paper discharge direction The edge effect may occur. In addition, deterioration of image quality such as poor dot reproducibility and poor graininess is observed.

(3) Silane Coupling Agent Example The magnetic substance-dispersed carrier particles according to the present invention preferably contain a silane coupling agent or the magnetic substance is surface-treated with a silane coupling agent. A silane coupling agent is an organosilicon monomer having two or more different reactive groups in its molecule, and one of the two reactive groups is a reactive group that chemically bonds with an inorganic substance (glass, metal, etc.) ( Methoxy group, ethoxy group, silanol group, etc.), the other reactive group is a reactive group (vinyl group, chemically bonded to the organic material,
Epoxy group, methacrylic group, amino group, mercapto group, etc.). Specific examples thereof include those shown in Table 1. In addition, KA1003 in Table 1
All are product names manufactured by Shin-Etsu Chemical Co., Ltd.

[0027]

[Table 1]

The amount of the silane coupling agent added is 0.15 to 40 parts by weight, preferably 0.25 to 30 parts by weight, based on 100 parts by weight of the binder resin. When the magnetic material is treated with a silane coupling agent, the silane coupling agent is dispersed in a solvent such as toluene to prepare a coating material coating solution, and this solution is sprayed onto the surface of the carrier core material by fluidization. It may be applied and then cured using a pellet method or the like.

The method of making the carrier is not particularly limited. For example, kneading and pulverization, classification method, spray drying method, polymerization method and the like are used.

[0030]

EXAMPLES The present invention will be described in detail with reference to examples. All parts are by weight.

Example 1 (Production of toner) To 100 parts of polyester resin,
Color toners of respective colors were obtained by using the coloring materials and charge control agents shown in Table 2.

[0032]

[Table 2] In the toner manufacturing method, kneading was performed on two rolls under heating, cooling was performed, and pulverization and classification were performed to obtain toner of each color having an average particle diameter of 7.5 μm.

(Production of Carrier) Styrene / n-butyl methacrylate (weight ratio 70/30) copolymer 100 parts Magnetic material (Table 3) 65 parts

[0034]

[Table 3] The components of each color system were melt-kneaded with a two-roll mill and classified to obtain a carrier having an average particle size of 40 μm.

This carrier and the toner of each color are used as carrier 1.
Toner of 4.5 parts was mixed with 00 parts of toner to prepare a developer of each color. The above developer was set in a color copying machine "Pritail 750" manufactured by Ricoh Co., Ltd., and when images were printed and 50,000 sheets of continuous copying were carried out, there were no background stains and color stains (secondary color smearing). There was no toner scattering. The image quality was extremely good.

Reference Example 1 The same toner as in Example 1 was prepared. (Manufacture of Carrier) Styrene / n-butyl methacrylate (weight ratio 70/30) Copolymer 100 parts Magnetic material EPT-1000 (manufactured by Toda Kogyo Co., Ltd.) 65 parts Melt kneading with a two-roll mill, followed by classification A carrier having an average particle size of 40 μm was obtained.

To 100 parts of this carrier, 4.5 parts of each color toner shown in Table 2 was mixed to obtain a developer of each color (yellow, magenta, cyan, black). The developer was set in a Ricoh color copier, "Pretail 750", and an image was printed. Looking at the copy image after 20,000 sheets, the green part and red part are blackish and not vivid,
As for the image quality, it was a light black color image and lacked in vividness. The reason for this is that the black magnetic material in the color developer is scraped, mixed into the yellow, magenta, and cyan developers of each color and developed by the dull developer.

Examples 2 to 3 and Reference Examples 2 to 3 (Production of Toner) The toner particles shown in Table 2 were changed in toner particle size as shown in Table 4.

[0039]

[Table 4]

The same carrier as in Example 1 was prepared. When these carriers and toners were used and tested in the same manner as in Example 1, Examples 2 to 3 obtained the same results as in Example 1. On the other hand, in Reference Example 2, when an image after 10,000 copies is seen, a background stain occurs and toner scatters when the inside of the machine is seen, and a part of the toner drops on the copy paper to accelerate the stain, resulting in image quality. Was not happy.
Further, since the image of Reference Example 3 did not have sufficient smoothness, a rough feeling was noticeable especially when the highlight part of the photograph was copied, and the image quality was not satisfactory.

Examples 4 to 5 and Reference Examples 4 to 5 The same toners as in Example 1 were prepared. In addition, as for the carrier, the carrier particle size shown in Table 3 was changed as shown in Table 5.

[0042]

[Table 5] Using these carriers and toners, the same method as in Example 1 was tested. In Examples 4 and 5, almost the same results as in Example 1 were obtained. On the other hand, in Reference Example 4, carrier scattering was observed, and carrier adhesion was caused on the image bearing member, and therefore white defects were large on the copy paper and the image quality was not satisfactory. Further, since the fluidity of the toner is not stable when the toner is replenished to the developing section, the uniform carrier and toner cannot be mixed, and scumming on copy paper occurs. Reference example 5
The solid uniformity was not good, and the highlight part was not particularly smooth, so that the image quality was not satisfactory.

Examples 6 to 9 The same toners as in Example 1 were prepared. The carrier is the styrene-n-butyl methacrylate of Example 1 in Table 6.
The same procedure as in Example 1 was repeated except that the above procedure was repeated.

[0044]

[Table 6] When a test was performed in the same manner as in Example 1 using these carriers and toners, the same results as in Example 1 were obtained even after copying 200,000 sheets. For comparison, when Example 1 was further copied from 50,000 to 200,000 sheets, the background stain was slightly conspicuous as compared with Examples 6 to 9. It is expected that the stability of Q / M was hindered because the toner was more likely to adhere to the surface of the carrier in Example 1.

Example 10 The same toner as that in Example 1 was prepared as the toner. In addition, the silane coupling agent (KBM60
3 manufactured by Shin-Etsu Chemical Co., Ltd.) was prepared in the same manner as in Example 1 except that 15 parts were added. When the same method as in Example 1 was tested using these carriers and toners, the same results as in Example 6 were obtained.

Example 11 The same toner as in Example 1 was prepared as a toner example. Further, the magnetic substance of Example 1 (Table 3) was immersed in a toluene solution of KBM603 silane coupling agent as a carrier and then dried (pretreatment), and then the carrier was prepared in the same manner as in Example 1. When the same method as in Example 1 was tested using these carriers and toners, the same results as in Example 6 were obtained.

Example 12 A carrier was prepared in the same manner as in Example 1 except that the magnetic substance in Table 3 was changed to that shown in Table 7 among the carriers in Example 1, and the same test as in Example 1 was conducted. As a result, the same result as in Example 1 was obtained.

[0048]

[Table 7]

Examples 13 to 16 Table 8 shows the silane coupling agent in the carrier of Example 10.
A carrier was prepared in the same manner as in Example 10 except that the carrier was changed to the one shown in, and the same test as in Example 10 was carried out. As a result, the same result as in Example 10 was obtained.

[0050]

[Table 8]

Example 14 The same carrier and toner as in Example 1 were prepared. These were mixed in the same manner as in Example 1 to prepare a developer of each color. Images of these developers were printed on a Ricoh color copier (Pritail 500, intermediate transfer member type) and were very good. In particular, there were no voids (transfer defects) in the character areas. Also, after passing 100,000 sheets, there was no background stain, no color stain, and no toner scattering in the machine. The image quality was extremely good.

 ─────────────────────────────────────────────────── ─── Continued front page (72) Inventor Yasutaka Iwamoto 1-3-6 Nakamagome, Ota-ku, Tokyo Within Ricoh Co., Ltd. (72) Minoru Masuda 1-3-6 Nakamagome, Ota-ku, Tokyo Stocks Inside Ricoh Company (72) Inventor Satomi Suzuki 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company

Claims (7)

[Claims] 1. A yellow developer is composed of a toner containing at least a yellow colorant and a binder resin and a magnetic substance dispersion type carrier containing at least a binder resin and a yellow magnetic substance, and the magenta developer is at least magenta. A toner containing a colorant and a binder resin, a magnetic substance dispersion type carrier containing at least a binder resin and a magenta magnetic substance, and a cyan developer is a toner containing at least a cyan colorant and a binder resin. And a magnetic material-dispersed carrier containing at least a binder resin and a cyan magnetic material, and the black developer contains at least a toner containing a black colorant and a binder resin and at least a binder resin and a black magnetic material. A color electrophotographic developer, comprising a magnetic substance-dispersed carrier contained therein. 2. The toner particles have a particle size of 3.0 to 8.5 μm.
The developer for color electrophotography according to claim 1, which is in the range of. 3. The particle diameter of the magnetic substance-dispersed carrier particles is 10.
The developer for color electrophotography according to claim 1, wherein the developer is in the range of ˜55 μm. 4. The color electrophotographic developer according to claim 1, wherein the binder resin of the magnetic substance-dispersed carrier particles contains a silicone resin as a main component. 5. The magnetic substance-dispersed carrier particles contain a silane coupling agent, or the magnetic substance in the carrier particles is surface-treated with a silane coupling agent. Or the developer for color electrophotography according to 4 above. 6. A first electrostatic latent image is formed on an image carrier,
After developing this with color developer A, the color toner is transferred to a transfer member, then a second electrostatic latent image is formed on the image carrier, and this is developed with color developer B. , The color toner is transferred onto the transfer member, and then a third electrostatic latent image is formed on the image carrier.
After the development, the color toner is transferred onto the transfer member in an overlapping manner, a fourth electrostatic latent image is formed on the image carrier, and the color toner D is developed. A color image forming method in which color toners on the transfer member are fixed after being superposedly transferred onto the transfer member, and the developer A, B, C and D is described in any one of claims 1 to 5. A color image forming method characterized in that different yellow developers, magenta developers, cyan developers, and black developers are used. 7. A first electrostatic latent image is formed on an image carrier,
After developing this with color developer A, the color toner was transferred to an intermediate transfer member, then a second electrostatic latent image was formed on the image bearing member, and this was developed with color developer B. rear,
The color toner is transferred to the intermediate transfer member, then a third electrostatic latent image is formed on the image carrier, and this is developed with a color developer C, and then the color toner is transferred to the intermediate transfer member. , A fourth electrostatic latent image is formed on the image bearing member, and the fourth electrostatic latent image is developed with a color developer D. Then, the color toner is transferred to the intermediate transfer member. A color image forming method of fixing the color toners after transferring the toner images that have been superposed and transferred onto another transfer member, wherein the developer A, B, C or D is any one of claims 1 to 5. A color image forming method characterized in that different yellow developers, magenta developers, cyan developers, and black developers as described are used.