JPH07181747A - Two-component color developing method - Google Patents

Abstract

PURPOSE:To obtain a two-component color developing method especially useful for a color machine by which contamination of the base, void or edge effect are prevented and high quality images can be obtd. CONSTITUTION:A latent image carrying body which carriers an electrostatic latent image on its surface is disposed to face a carrying body of a two- component developer comprising carrier particles and toner particles. The both carrying bodies are disposed with 0.4 to 0.7mm distance. In this method of developing the latent image, the toner contains particles having <=4mum particle size by 5 to 25 number % and particles >=16mum particle size by <=1vol.%, and has 5.0 to 8.5mum volume-average particle size. The carrier particles consist of spherical cores having 30 to 65mum average particle size coated with a silicone resin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for developing an electrostatic charge image using a two-component developer, which is preferably used in electrophotography, electrostatic printing and the like.

[0002]

2. Description of the Related Art Conventionally, as disclosed in Japanese Patent Application Laid-Open No. 61-147261, methods for developing an electrostatic image with toner are roughly classified, and so-called two-component system in which toner and carrier are mixed. There are a method of using a developer and a method of using a one-component developer which is used alone as a toner without being mixed with a carrier. In the above-mentioned method, the toner and the carrier are stirred and rubbed so that they are charged to different polarities, and an electrostatic image having opposite polarities is visualized by the charged toner. There are a magnetic brush method using an iron powder carrier, a cascade method using a bead carrier, a fur brush method, and the like. As the toner applied to these various developing methods, fine powder in which a colorant such as carbon black is dispersed in a binder resin made of a natural resin or a synthetic resin is used. For example, a binder resin such as polystyrene having a colorant dispersed therein is 1 to 30 μm.
Particles finely pulverized to some extent are used as toner.
Further, a magnetic toner such as those containing a magnetic material such as magnetite is used as a magnetic toner.

Conventionally, as a technique of using a two-component developer, a toner particle size is specified (Japanese Patent Laid-Open No. 2-877).
Japanese Patent Laid-Open No. 207275), one using a polyester color toner and a carrier coated with a styrene resin and a fluororesin (Japanese Patent Laid-Open No. 168266), one using a ferrite carrier of 40 to 65 μm (Japanese Patent Laid-Open No. 2-207275).
JP-A-2-129654), which uses quinacridone and a methine colorant to define carrier properties such as particle size, particle size distribution, and magnetism (JP-A-2-129654). (Japanese Patent Application Laid-Open No. 61-120172), and one in which the amount of metal oxide of the carrier is specified (Japanese Patent Application Laid-Open No. 62-1789).
No. 77). However, these prior arts cannot sufficiently deal with high quality images, especially color images.

[0004]

SUMMARY OF THE INVENTION The present invention is directed to a developing method using a two-component developer capable of overcoming the drawbacks of the prior art and obtaining a high-quality image with improved background stains, voids, edge effects and the like. I will provide a. Particularly, it is effective for a color machine.

[0005]

Means for Solving the Problems As a result of intensive studies made by the present inventor, the above problems can be solved by defining the toner particle size in a specific range and using carrier particles coated with a silicone resin. This led to the present invention. That is, in the present invention, a carrier of a two-component developer composed of carrier particles and toner particles is opposed to a latent image carrier that holds an electrostatic latent image on its surface, and the gap between the two carriers is set to 0. In the image forming method of developing the latent image bearing member by disposing the toner particles of 4 to 0.7 mm, the toner particles contain 5 to 25% by number of particles having a particle diameter of 4 μm or less and a volume average particle diameter of 5.0 to It is characterized in that it is 8.5 μm, 1% by volume or less of particles having a particle size of 16 μm or more is contained, and the carrier particles are formed by coating a silicon resin of a spherical core material having an average particle size of 30 to 65 μm. It is the developing method.

Generally, the coating layer is provided on the carrier particles in order to prevent the toner from adhering to the carrier particles. Therefore, a low surface energy substance is preferable, and a substance having a small critical surface tension (γc) is preferable. As examples thereof, fluorine resin (γc = 16 to 19), silicon resin (γ
c = 21) and styrene resin (γc = 33). The fluororesin-based resin easily forms a film on the latent image bearing member and significantly deteriorates the electrostatic characteristics of the latent image bearing member. In particular, it leads to an increase in residual potential, which significantly deteriorates image quality such as background stain. Further, since styrene resin has a large γc, when a developer is used for a long period of time, toner adheres to the carrier coating layer, resulting in a decrease in charge amount (Q / M), an increase in carrier resistance, etc. Is significantly reduced.
For example, scumming, toner scattering, edge effect, etc. occur. Therefore, in the present invention, the above-mentioned drawbacks are eliminated by using a silicone resin. The Q / M will be described. The toner charge amount (Q / M) of the two-component developer is mainly determined by the blow-off method. The toner and the carrier are charged with opposite polarities, and the toner adheres to the surface of the carrier due to electrostatic force.
An appropriate amount of this developer is sampled and placed in a conductor container having wire netting at both ends.

When the mesh of this wire mesh is selected to have an intermediate particle size between the toner and the carrier and a compressed gas is blown from the nozzle toward the wire mesh, only the toner is blown through the wire mesh (blow-off). As a result, a carrier charge appears in the container. This charge is measured by an electrometer. It is assumed that what has changed the sign is the electric charge possessed by the toner. The sample mass before and after the blow-off is measured with a balance, and the charge amount (Q / M) per unit mass of the toner is obtained. The two-component developer forms a magnetic brush, and the toner is separated from the carrier in the latent image portion to be developed. If the Q / M is abnormally high, it is difficult to develop. On the contrary, if the Q / M is too low, the toner is scattered but the background stain of the copy becomes noticeable. Further, in the present invention, the toner particle size is specified to improve the image quality, and the carrier resistance is also specified to obtain a smooth image quality without edge effect. For example, the toner cohesion is regulated to improve the transferability of the toner, the carrier magnetic properties are regulated to obtain a soft and smooth image without carrier scattering, and the toner concentration is regulated to obtain a certain developing ability. There are modes. The constitution of the toner used in the present invention will be described below.

Examples of the binder resin for the toner used in the present invention include polystyrene, chloropolystyrene, and poly-α.
-Methylstyrene, styrene-chlorostyrene copolymer, styrene-propylene copolymer, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer, styrene-maleic acid copolymer, Styrene-acrylic acid ester copolymer (styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer,
Styrene-octyl acrylate copolymer, styrene-phenyl acrylate copolymer, etc.), styrene-methacrylic acid ester copolymer (styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-methacryl) Butyl acid copolymers, styrene-phenyl methacrylate copolymers, etc., styrene-α-chloromethyl acrylate copolymers, styrene-acrylonitrile-acrylic acid ester copolymers, and other styrene resins (styrene or styrene substitutes) Containing a homopolymer or copolymer), vinyl chloride resin, rosin-modified maleic acid resin, phenyl 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. are used.

As the colorant of the toner used in the present invention,
Examples of yellow colorants include C.I. I. Pigment Yellow 1, 12, 13, 14, 17 and the like are used, and examples of magenta colorants include C.I. I. Pigment Red 81, 122, 57, 22, 21, 18, 114, 1
12, 5 and the like are used, and examples of cyan colorants include C.I. I. Pigment Blue 15, 16, 15: 3, C.I. I. Pigment Green 7, 36 and the like are used, and examples of colorants for black include carbon black, split black, aniline black (C.I.
Pigment Black 1) and the like are used. These may be commercially available products.

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.

In the present invention, a nigrosine dye, a chromium-containing complex, a quaternary ammonium salt or the like is used as the charge control agent, and these are properly used depending on the polarity of the toner particles. In the case of a color toner, a colorless or light-colored one that does not affect the color tone of the toner is preferable. For example, a metal salt of salicylic acid or a metal salt of a salicylic acid derivative (Bontron E84 = manufactured by Orient Co.) The amount of the control agent is 100 parts by weight of the binder resin. To 0.1-10
More preferably 0.2 to 7 parts by weight. Next, a fluidity imparting agent may be added to the obtained toner particles.

In the present invention, as the fluidity-imparting agent, fine particles of metal oxides such as silica, alumina, magnesia, zirconia, ferrite and magnetite, and those fine particles are used as silane coupling agents, titanate coupling agents, zircoaluminates, Fine particles of fatty acid or its metal salt such as stearic acid and zinc stearate, and those fine particles thereof, which have been surface-treated or coated with a treating agent such as graded ammonium salt, fatty acid, fatty acid metal salt, fluorine-based activator, solvent and polymer Polymer fine particles such as polystyrene, polymethylmethacrylate, and polyvinylidene fluoride that are surface-treated with the above-mentioned treatment agent, and those obtained by surface-treating or coating these fine particles with the above-mentioned treatment agent are used. The average particle size of these fluidity-imparting agents is 0.01 to 3
Those in the μm range are used. The amount of the fluidity-imparting agent added is 0.1 to 100 parts by weight of the toner particles.
It is preferably in the range of 7.0 parts by weight, particularly 0.2 to 5.0 parts by weight.

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 that the powder is not substantially pulverized. The mixer is a high-speed flow type mixer, for example, a Henschel mixer, a UM mixer or the like. As a 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 and a colorant such as carbon black and necessary additives are dry-mixed, and heat-melted and kneaded with an extruder, a two-roll roll, a three-roll roll or the like, and after cooling and solidification. A 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 colorant and an additive by a suspension polymerization method or a non-aqueous dispersion polymerization method. Toner particle size is measured by COULTE
An R COUNTER MODEL T _A II type (manufactured by Beckman Coulter, Inc.) is used to connect an interface for outputting a number distribution volume distribution, and an 100 μ aperture (pore) is used. First, a toner measurement sample was dispersed in a surfactant added to an electrolytic aqueous solution. The sample was injected into another 1% NaCl electrolytic solution, and an electric current was passed between both electrodes through the electrolytic solution in which electrodes were placed on both sides of the aperture of the aperture tube. The distribution was measured, and from the volume average distribution and the number average distribution, the value of the number average of the volume average particle diameter of 4 μm or less and the value of 16 μm volume% or more were obtained.

The volume average particle diameter is preferably 5 to 8.5 μm, more preferably 5.5 to 8.0 μm. Particle size is 8.5 μm
If it is above, the dot reproducibility is not good in the digital copying machine. In addition, since smooth gradation cannot be obtained, the highlight portion has a grainy feeling and the image quality is deteriorated particularly when a color original document is copied. If the thickness is 5 μm or less, the toner easily adheres to the surface of the carrier coating layer and Q / M
Deteriorates and becomes a factor of contamination in the machine due to toner scattering. In addition, scumming is also likely to occur. Particle size less than 4μm is 2
When it is contained in an amount of 5% by number or more, the fluidity of the toner deteriorates, and for example, development unevenness or transfer unevenness occurs at the time of development or transfer, and transfer blanks (blanks) occur, resulting in poor image quality. Further, the transferability also deteriorates. The number of particles having a particle size of 4 μm or less of 5% by number is a level at which no particular problem occurs if the above is suppressed from the viewpoint of accuracy and cost of the classification step during manufacturing. If the particle size of 16 μm or more is contained in an amount of 1% by volume or more, such a toner is liable to be dusty at the time of transfer, so that the phosphorus portion is unclear. Q /
Since M is low, toner easily adheres to the non-image area. Further, when it is fixed, it becomes extremely conspicuous as background stain. Further, the cleaning felt of the fixing roller is soiled due to the soiling.

Next, the carrier will be described. The core material of the resin-coated carrier that can be used in the developer of the present invention is, for example, ferrite or magnetite. The core material has a particle size of 20 to 65 μm, preferably 3
About 0 to 60 μm is suitable.

Next, as a releasing resin for carrier coating, a polyolefin resin such as polyethylene,
Polypropylene, chlorinated polyethylene, and chlorosulfonated polyethylene; polyvinyl and polyvinylidene resins such as polystyrene, acrylic resin (eg polymethylmethacrylate), polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, Polyvinyl ethers and polyvinyl ketones; vinyl chloride-vinyl acetate copolymers; styrene-acrylic acid copolymers; silicone resins such as straight silicone resins consisting of organosiloxane bonds or modified products thereof (for example, alkyd resins, polyesters, epoxy resins, Modified products with polyurethane, etc.); Fluorine resins such as polytetrafluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, polychlorotrif Oroechiren; polyamides; polyesters such as polyethylene terephthalate; polyurethanes; polycarbonates; amino resins such as urea - formaldehyde resins, epoxy resins and the like. Of these, acrylic resins, silicone resins or modified products thereof, and fluororesins, particularly silicone resins or modified products thereof, are preferable from the viewpoint of preventing the spent toner from adhering to the carrier. Silicone resin (however, straight silicone resin)
Commercially available products of Shin-Etsu Chemical KR271, KR25
5, KR251, Torre Silicon Co. SR2400, S
R2406, etc., and as the modified silicone resin, Shin-Etsu Chemical's KR206 (alkyd resin modified product), KR
3093 (modified acrylic resin), ES1001N (modified epoxy resin), SR2115 manufactured by Torre Silicone
(Epoxy resin modified product), SR2110 (alkyd resin modified product) and the like.

It is appropriate that the amount of the releasing resin used as described above is about 0.1 to 50 parts by weight per 100 parts by weight of the carrier core material. It is more preferably 0.5 to 30 parts by weight. The following may be mentioned as specific examples of the conductive material. (A) White conductive material ETC-52 (TiO ₂ system) Titanium Industry Co., Ltd. KV400 (TiO ₂ system) Titanium Industry Co., Ltd. ECR-72 (TiO ₂ system) Titanium Industry Co., Ltd. ECTR-82 (TiO ₂ system) Titanium Kogyo Co., Ltd. 500W (TiO ₂ system) Ishihara Sangyo Co., Ltd. 300W (TiO ₂ system) Ishihara Sangyo Co., Ltd. s-1 (TiO ₂ system) Ishihara Sangyo Co., Ltd. W-1 (SnO ₂ system) Mitsubishi Metal Corp. 23K (ZnO) ) Hakusui Chemical Co., Ltd. Conductive Zinc Flower No. 1 (ZnO) Honjo Chemical Co., Ltd. Conductive Zinc Flower No. 2 (ZnO) Honjo Chemical Co., Ltd. W-10 (TiO ₂ system) Mitsubishi Metal Industries Dentor WK-100 ( conductive fiber) manufactured by Otsuka Chemical Co. DENTALL WK-200 (conductive fiber) manufactured by Otsuka Chemical Co. DENTALL WK-300 (conductive fiber) manufactured by Otsuka Chemical Co. MEC300 (SnO ₂ system) Teikoku Kako Co. MEC50 (SnO ₂ system) Teikoku Kako Co., Ltd. (ii) Carbon Black Pearls 2000, VULCANX
C-72 (manufactured by Cabot) Ketjen black EC / DJ500, Ketjen black EC / DJ600 (manufactured by Lion Akzo) Denka black granular, Denka black powder (manufactured by Denki Kagaku Kogyo) CONDUCTEX-975, CONDUCTEX S
C (manufactured by Columbia Carbon Co., Ltd.) The amount of the conductive substance is 0.05 to 70 parts by weight, more preferably 0.1 to 50 parts by weight, and, if necessary, the coating layer, based on 100 parts by weight of the silicone resin. A silane coupling agent may be added to the above-mentioned coating layer in order to improve the adhesive strength, to improve the dispersibility of the conductive material, and to adjust the Q / M.

As in the conventional case, the coating layer is formed on the surface of the carrier particles by means such as a spraying method or a dipping method so that the carrier particle diameter is 30.
˜65 μm, more preferably 40 to 60 μm. 65
When it is more than μm, the solid uniformity is poor and the solid part is scratched by the carrier. Further, when a picture original is copied, an edge effect occurs at the leading edge of the image (with respect to the copy sheet discharge direction). In addition, deterioration of image quality such as poor dot reproducibility and poor graininess can be seen. 30μ
If it is less than the above range, the carrier is likely to adhere to the carrier and the granules are likely to be formed during the carrier coating during the production, resulting in a large decrease in the yield and an increase in the cost. Further, carrier scattering from the developing sleeve becomes significant. When the carrier is spherical, the solid uniformity, the carrier scratch on the solid portion, the leading edge effect of the image portion, the dot reproducibility, and the like are excellent as compared with the irregular shape. Further, the spent toner is unlikely to adhere to the carrier. The magnetic properties of the carrier are measured using VSM-P7-15 (manufactured by Toei Industry Co., Ltd.). A sample weighs about 0.15 g and has an inner diameter of 2.
It is filled in a cell having a diameter of 4 mm and a height of 8.5 mm, and σ _r is obtained under a magnetic field of 5000 Oersted (Oe). At this time, σ _r = 1 to 10 emu / g and H _c = 0 to 30 Oe.

The volume resistivity of carrier particles is 10 ⁸ to 1
0 ¹⁴ Ωcm is preferable. The edge effect of 10 ¹⁴ Ωcm or more becomes large, and it is not good especially when copying a color picture original. If it is 10 ⁸ Ωcm or less, carrier adhesion is likely to occur. In particular, when the carrier resistance is set to the setting of 0.4 to 0.7 mm for the latent image carrier to the developer carrier as in the process of the present invention, the image quality becomes extremely good. By providing a specific gap, the intensity of the electric field formed in the development area by the latent image is increased, and as a result, by setting the above carrier resistance, subtle changes in gradation and fine patterns can be developed neatly. It was The method for measuring the specific resistance is as follows. Area 10 cm ² (length 4c
m, width 2.5 cm) two electrode plates facing each other at an interval of 2 mm to allow the sample to flow into the cell to the extent that it overflows, and then in this state, drop it from a position of 15 mm in height onto a flat plate. The tapping operation is repeated 30 times to tightly fill the cell with the sample. Next, after removing the excess sample on the cell, a voltage corresponding to a DC electric field of 500 V / cm is applied to the electrode plate in an environment of 20 ° C. and 60% RH to determine the specific resistance.

The toner cohesion is an index showing the adhesive force between the toners, and when the value is large, the adhesive force between the toners is large and the flight property of development is deteriorated. On the contrary, if the value is small, scumming is likely to occur. Therefore, in the toner of the present invention,
It is preferable that the degree of cohesion obtained when 2 g of toner is charged is 15 or less when the sieves of 75 μm, 45 μm and 22 μm are arranged in series in that order. The cohesion of the toner in the present invention is measured by using a powder tester (manufactured by Hosokawa Micron Co., Ltd.), and sieves having openings of 75 μm, 45 μm, and 22 μm are arranged in this order from the top to open the openings of 75 μm.
2g of toner was put into the m-type sieve and the amplitude was 1mm.
Vibration is applied for 0 second, the toner weight on each sieve is measured after the vibration, and 0.5, 0.3, and 0.1 weights are applied to the respective weights, and the results are calculated as a percentage.

When the cohesion degree is 15 or more, unevenness occurs at the time of transfer after the toner is developed for each color and superposed. As a result, transfer gaps (blanks in letters) are likely to occur. or,
Toner easily sticks to the developing sleeve. Particularly, as in the process of the present invention, the latent image carrier and the developer carrier 0.4 to 0.7
When it is set to a narrow value such as mm, it becomes significantly easier to adhere. When it is 15 or less, the fluidity is good, and the toner is good even when the toners are superposed, and the transfer is carried out very smoothly. The carrier core material is preferably of ferrite or magnetite type. As the ferrite, Ni-Zn, Mn-Zn, C
A u-Zn system or the like is used. Magnetite (Fe ₃ O ₄ ) has a saturation magnetization (σ _s ) larger than that of ferrite, so even if the carrier particle size is made smaller, σ _s is comparatively larger than that of ferrite, so the carrier scatters from the sleeve or carries a latent image. It can be prevented from sticking to the body. Also, Fe ₂
Since O ₄ itself is relatively conductive, the carrier coating layer is thickened while maintaining the carrier resistance. This σ _s
When it is 55 emu / g or less, carrier scattering and carrier adhesion are likely to occur, and when it is 85 emu / g or more, the developing torque increases and the carrier coating layer deteriorates. For example, the deviation of the coating layer, the accompanying adhesion of spent toner,
As a result, the Q / M is lowered, the carrier resistance is changed, and streaks are easily formed on the image.

In the method of the present invention, the carrier resistance can be freely controlled by adding a conductive material to the carrier coating layer. Further, even if the film thickness is increased, the desired carrier resistance can be easily obtained, which is also advantageous for film abrasion. It is also possible to adjust the Q / M level depending on the material to be added. The material used for the color carrier is preferably an achromatic color material as much as possible, and a chromatic color material is preferably in a form in which the addition amount is as small as possible. The reason for this is that due to film scraping, a chromatic color causes color stains, resulting in a dull shape with respect to the base color. In particular, it tends to occur remarkably in the yellow agent.

The toner concentration in the developer is preferably 4 to 10% with respect to the carrier particles. A manuscript of a color copying machine generally has many pictures and is close to a solid image, and thus has a large image area. Therefore, if the toner concentration is 4% or less, the development of the solid uniformity is not sufficient, and for example, the solid portion becomes a solid image with a lot of thin unevenness, and the copy is not powerful. When the toner concentration is 10 parts by weight or more, the amount of floating toner that cannot be fully charged with the carrier increases. Further, the agent Q / M becomes too low, which causes scumming. Further, the toner is scattered in the machine. In the case of color, for example, the toner scattered by the yellow agent may be mixed with the magenta agent to deteriorate the color characteristics. In this case, the development gap is 0.
Since it is 4 to 0.7 mm, the developing electric field is large, and by setting the toner density to 4 to 10%, it is possible to obtain a copy without insufficient density even for the original of a picture.

[0025]

EXAMPLES The present invention will be described in more detail below with reference to examples. Example 1 A full-color toner was obtained by using the colorant and the charge control agent shown in Table 1 with respect to 100 parts of the polyester resin.

[0026]

[Table 1]

In the toner manufacturing method, kneading was carried out on two rolls under heating, and after cooling, pulverization and classification were carried out to obtain toner of each color having a particle size shown in Table 2. To 100 parts of each toner, silica (R972, Nippon Aerosil Co., Ltd.) was externally added at a ratio of 0.6 part.

[0028]

[Table 2]

As carrier particles, a coating liquid was prepared as a carrier coating material according to the following formulation. Silicone resin liquid (Toray Silicone SR2406, solid content 20%) 200 parts Toluene 1500 parts Average particle size 50 in a rotating disk type fluidized bed particle coating device
5 μm of ferrite carrier of μm was poured and the coating liquid of the above formulation was sprayed under heating at 80 ° C., the coated material was taken out from the coating device and placed in a constant temperature bath, and heated at 200 ° C. for 2 hours. The silicone film was cured.

A two-component developer was prepared by mixing 5 parts of each color of toner with the carrier so that the total amount was 100 parts. The above-mentioned developer is modified from Puritail 550 (a color copying machine manufactured by Ricoh) and each YM CBK developer is set in a machine in which the gap between the latent image carrier and the developer carrier is 0.5 mm, and an image is output. Was carried out. The results are shown in Table 10. The image density was measured with RD514 (Macbeth densitometer).

Example 2 The same test as in Example 1 was carried out except that the toner particle size in Example 1 was changed as shown in Table 3, and the results shown in Table 10 were obtained.

[0032]

[Table 3]

Example 3 The carrier of Example 1 was changed as follows. As the carrier particles, a coating liquid was prepared as a carrier coating material according to the following formulation.

Silicone resin liquid (Toray Silicone SR2406, solid content 20%) 300 parts Toluene 1500 parts Rotating disk type fluidized bed particle coating device has an average particle size of 30
5 μm of ferrite carrier of μm was poured and the coating liquid of the above formulation was sprayed under heating at 80 ° C., the coated material was taken out from the coating device and placed in a constant temperature bath, and heated at 200 ° C. for 2 hours. The silicone film was cured.

A two-component developer was prepared by mixing 5 parts of each color of toner with the carrier so that the total amount would be 100 parts. When the same test as in Example 1 was performed using the carrier and the toner of Example 1, the same result as in Example 2 was obtained.

Example 4 The carrier of Example 1 was changed as follows. As the carrier particles, a coating liquid was prepared as a carrier coating material according to the following formulation. Silicone resin liquid (Toray Silicone SR2406, solid content 20%) 180 parts Toluene 1500 parts Rotating disk type fluidized bed particle coating device with an average particle size of 60
5 μm of ferrite carrier of μm was poured and the coating liquid of the above formulation was sprayed under heating at 80 ° C., the coated material was taken out from the coating device and placed in a constant temperature bath, and heated at 200 ° C. for 2 hours. The silicone film was cured.

A two-component developer was prepared by mixing 5 parts of each toner of Example 1 with the carrier so that the total amount was 100 parts. When the same test as in Example 1 was performed using the carrier and the toner of Example 1, the same result as in Example 2 was obtained.

Example 5 The same results as in Example 1 were obtained when tested in the same manner as in Example 1 except that the gap between the latent image carrier and the developer carrier was changed to 0.7 mm. Example 6 The same result as in Example 1 was obtained when tested in the same manner as in Example 1 except that the gap between the latent image carrier and the developer carrier was changed to 0.4 mm.

Examples 6 to 7 The polyester resin (in the toner) of Example 1 was changed to a styrene resin (Example 6) and an epoxy resin (Example 7), and otherwise the same method as in Example 1 was used. When tested, the same results as in Example 1 were obtained. Comparative Examples 1 to 2 The toner particle size in Example 1 was changed as shown in Table 4, and the same method as in Example 1 was tested.

[0040]

[Table 4]

Comparative Example 1 has many particle sizes of 16 μm or more, and Comparative Example 2 has many particle sizes of 4 μm or less. The test results are shown in Table 12. Comparative Examples 3 to 4 Tests were performed in the same manner as in Example 1 except that the toner particle size in Example 1 was changed as shown in Table 5. Comparative Example 3 has an average particle size of 5 μm or less and 16 μm or more and 1% or more, and Comparative Example 4 has a particle size of 4 μm or less and 25% or more.
The test results are shown in Table 13.

[0042]

[Table 5]

Comparative Example 5 A test was conducted in the same manner as in Example 1 except that the carrier particle size in Example 1 was changed to 25 μm. Comparative Example 6 A test was performed in the same manner as in Example 1 except that the carrier particle size in Example 1 was changed to 70 μm. The results are shown in Table 14.
Shown in. Comparative Example 7 When the same test as in Example 1 was carried out except that the carrier coating layer in Example 1 was changed from silicon to methyl methacrylate resin, the results shown in Table 16 were obtained. Examples 8 to 9 and Comparative Examples 8 to 9 Tests were performed in the same manner as in Example 1 except that the amount of carrier coating material was changed as shown in Table 6 to change the carrier resistance.

[0044]

[Table 6]

As a result, the same results as in Example 1 were obtained in Examples 8 to 9. Comparative Examples 8 and 9 are shown in Table 14. Examples 10 to 11 and Comparative Example 10 Tests were conducted in the same manner as in Example 1 except that the amount of silica externally added to the toner in Example 1 was changed as shown in Table 7, and Examples 10 and 11 were compared to Example 11. I got the same result.
Further, in Comparative Example 10, the results shown in Table 14 were obtained.

[0046]

[Table 7]

Examples 12 to 13 and Comparative Examples 11 to 12 The same test as in Example 1 was carried out except that the carrier core material in Example 1 was changed as shown in Table 18.
13 obtained the same result as in Example 1. In addition, Comparative Examples 11 to 1
2 obtained the results shown in Table 15.

[0048]

[Table 8]

Example 14 The same test as in Example 1 was carried out except that the carrier coating layer in Example 1 was changed as follows. As the carrier particles, a coating liquid was prepared as a carrier coating material according to the following formulation.

Silicone resin liquid (Toray Silicone SR2406, solid content 20%) 500 parts Conductive material Ketjen Black ECDJ600 (Lion Akzo Co., Ltd.) 4.0 parts Toluene 1500 parts Average particle size in a rotating disk type fluidized bed particle coating device Fifty
5 kg of a ferrite carrier of μm was poured and the coating solution of the above formulation was sprayed under heating at 80 ° C., the coated material was taken out from the coating device, placed in a constant temperature bath, and heated at 200 ° C. for 2 hours to cure the silicone. The film was allowed to cure. The results are the same as in Example 1.

Comparative Example 13 The same test as in Example 1 was carried out except that the coating layer was formed in the same manner as in Example 14 except that the conductive material in the carrier coating layer: Ketjenblack EC-DJ600 was omitted. I got good results. Examples 15 to 16 and Comparative Examples 14 to 15 The same tests as in Example 1 were performed in the same manner as in Example 1 except that the toner concentration of the developer was changed as shown in Table 9.

[0052]

[Table 9]

In Examples 15 to 16, the same results as in Example 1 were obtained. In Comparative Examples 14 to 15, the results shown in Table 16 were obtained. Comparative Examples 16 to 17 In Example 1, the gap between the latent image carrier and the developer carrier is 0.3 mm (Comparative Example 16) and 0.8 mm (Comparative Example 17).
The test was performed in the same manner as in Example 1 except that the above was changed.
The results are shown in Table 16.

[0054]

[Table 10]

[0055]

[Table 11]

[0056]

[Table 12]

[0057]

[Table 13]

[0058]

[Table 14]

[0059]

[Table 15]

[0060]

[Table 16]

[0061]

[Table 17]

[0062]

As described above, according to the present invention, (1) the gap is regulated to 0.4 to 0.7 mm, the latent image is regulated the toner particle size while maintaining an effective electric field strength, and By using a silicone resin coated carrier with a specified particle size, a fine pattern with good gradation can be reproduced, and since the spent toner does not easily adhere to the carrier due to the silicone resin coated carrier, it can be used as a long-life developer. Become.

(2) The edge effect can be prevented by defining the carrier resistance. (3) By regulating the toner cohesion degree, the fluidity of the toner is kept good to prevent hollowing (transfer failure) when an unfixed toner image is transferred to a support, and to prevent uneven development during latent image development. it can.

(4) By defining the carrier core material, it is possible to prevent streak carrier scattering during development. (5) By adding a conductive material to the carrier coating layer,
It was made possible to freely change the carrier resistance due to the carrier coat. (6) By defining the toner density, it is possible to obtain a stable image while keeping the developing ability constant.

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical indication location G03G 9/107 13/08 15/08 507 X L G03G 9/08 381 9/10 321 361 13/08 (72 ) Inventor Hidefumi Gohara 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Megumi Sakakura 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd.

Claims (6)

[Claims] 1. A carrier for a two-component developer composed of carrier particles and toner particles is opposed to a latent image carrier that holds an electrostatic latent image on its surface, and a gap between the two carriers is 0.4. ~
In the image forming method of developing the latent image bearing member by disposing it at 0.7 mm, the toner particles contain 5 to 25% by number of particles having a particle diameter of 4 μm or less, and have a volume average particle diameter of 5.0 to 8.5.
The average particle size of the carrier particles is 30 to 30 μm and the average particle size of the carrier particles is 30 to 30 μm.
A developing method comprising a spherical core material of 65 μm coated with a silicone resin. 2. The volume resistivity of carrier particles is from 10 ⁸ to
The developing method according to claim 1, wherein the developing amount is 10 ¹⁴ Ωcm. 3. The aggregation degree of the toner particles is 2 in the screen having openings 75 μm, 45 μm and 22 μm arranged in series.
2. The developing method according to claim 1, wherein a value obtained by adding g toner is 15 or less. 4. The carrier core material has a saturation magnetization of 55 to 85e.
The developing method according to claim 1, wherein the developing method is made of ferrite or magnetite having a mu / g. 5. The developing method according to claim 1, wherein a conductive material is dispersed in the coating layer of carrier particles. 6. The developing method according to claim 1, wherein the toner particles of the developer are mixed at a ratio of 4 to 10% with respect to the carrier particles.