JPH112926A - Electrophotographic carrier and its manufacture and developer and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the resin-coated carrier superior in durability and stability against environmental conditions and resistance to surface staining and capable of giving a proper amount of positive or negative charge to a toner by radically polymerizing a monomer from photoreactive groups as the reaction initiating points introduced on a core material to form a resin coated layer. SOLUTION: The photoreactive groups are chemically combined with the surface of each core material or physically adsorbed to the surface and then mixed with the monomer radically polymerizable with these groups under irradiation with light to form the resin layer by radical polymerization. The photoreactive groups are introduced by using a silane coupling agent having groups capable of chemically combining with organic material, or chemically combining a photoinitiator having a polymerization condensation group directly with the core material, or allowing the photoinitiator to be adsorbed directly into the core material or introducing it into a resin to allow it to be adsorbed physically into the core material. The preferable monomer radically polymerizable with the photoreactive groups, to be used is that giving a negative or positive charge to the toner.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic carrier used for developing an electrostatic latent image formed by an electrophotographic electrostatic recording method, a method for manufacturing the same, a developer, and
The present invention relates to an image forming method using the developer.

[0002]

2. Description of the Related Art Conventionally, when developing an electrostatic latent image formed by an electrostatic recording method, a carrier is used to impart an appropriate amount of positive or negative charge to toner. For the purpose of improving the durability of the carrier and ensuring environmental stability, surface contamination resistance, and the like, a coated carrier in which a carrier core material is coated with a resin is widely used.

[0003] As a method of producing this coated carrier,
Generally known are a kneader coater method in which a resin is dissolved in an organic solvent, and heating and stirring using a kneader coater apparatus, and a fluidized bed method in which a resin liquid is coated on a carrier surface using a fluidized bed coating apparatus. .

[0004] For example, in Japanese Patent Application Laid-Open No. 58-202457, a coating liquid is sprayed while a carrier core material is suspended in a fluidized bed, dried at a high temperature, and then a coating liquid is sprayed again, and drying is repeated. Manufacturing methods have been proposed. Further, Japanese Patent Application Laid-Open No. 62-153962 proposes a method in which a coating liquid is sprayed while a carrier core material is caused to float or flow, and a coating layer is formed on the carrier core material while applying a shearing force.

Further, Japanese Patent Application Laid-Open No. 3-140969 proposes a method of coating by controlling the temperature of a fluidizing gas and the resin concentration of a coating resin liquid in a fluidized bed coating apparatus. Further, JP-A-5-216284 and JP-A-5-216285 disclose a method of intermittently spraying a resin liquid while controlling an atmospheric temperature in a fluidized bed of a fluidized bed coating apparatus, and a method of spraying a resin liquid in a fluidized bed. A method of performing spraying by controlling the ambient temperature and the amount of flowing air has been proposed.

However, when spray coating is performed while forming a fluidized bed, depending on the spraying state and the state of formation of the fluidized bed, agglomeration of carrier particles occurs or the coating resin does not adhere to the carrier core material during spraying. However, there is a problem that particles of the resin alone are formed.

Further, even if the resin can be coated to a certain extent on the carrier core material, a resin coating having a uniform surface property is formed so as to control the covering rate and hardly expose the carrier core material. It was difficult. Furthermore, in these coating methods, it is difficult to obtain a high yield of the carrier, and the obtained coated carrier also has insufficient adhesion between the carrier core material and the coating resin. There was a problem.

In order to solve these problems, an attempt has been made to improve the adhesion between the coated resin and the carrier core material by treating the carrier core material with a silane coupling agent and then coating the resin with the resin. is there. For example, JP-A-58-
196550, JP-A-60-221767, JP-A-60-196778, JP-A-61-7
No. 849. However, with these methods,
The carrier core material and the coating resin are not chemically bonded, and the adhesion is not sufficient. Further, when a water-soluble resin or the like is used as the coating resin, there is a possibility that the resin may be melted when the humidity rises, and there is a problem that the selection range of the coating resin is limited.

[0009]

SUMMARY OF THE INVENTION Accordingly, the present invention has been made to solve the above-mentioned problems, and has been able to impart an appropriate amount of positive or negative charge to a toner, and has excellent durability and environmental stability. The present invention is intended to provide a resin-coated carrier having a surface contamination resistance, and further expands a selection range of the coating resin to control the coating state and improve the reliability, and a method of manufacturing the same. And a developer, and an image forming method using the developer.

[0010]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, after introducing a photoreactive group on a core material, a monomer component is used by using the photoreactive group. The inventors have found that the above-mentioned problems can be solved by a method for producing an electrophotographic carrier, which is characterized by forming a resin layer by radical polymerization, and have completed the present invention. That is,
The configuration of the present invention is as follows.

(1) A photoreactive group is chemically bonded or physically adsorbed on a core material, and then the photoreactive group and a monomer component which undergoes radical polymerization are mixed under light irradiation. A method for producing an electrophotographic carrier, comprising forming a resin layer on the core material by radical polymerization.

(2) As a method for introducing a photoreactive group onto the core material, a photoinitiator into which a polycondensation group is introduced via a silane coupling agent having a reactive group chemically bonded to an organic material is used. For the electrophotography according to the above (1), wherein the method is to chemically bond directly to the core material, or to directly adsorb the photoinitiator or the resin to the core material by introducing into the resin. Carrier manufacturing method.

(3) As the monomer component capable of undergoing radical polymerization with the photoreactive group, a resin monomer that imparts a negative or positive charge to the toner is used.
A method for producing the electrophotographic carrier according to (1).

(4) The method for producing a carrier for electrophotography according to the above (3), wherein a fluorine-containing monomer having a surface contamination resistance copolymerizable with the monomer component described in the above (3) is used in combination.

(5) A monomer which is copolymerizable with the monomer component described in (3) and controls physical properties such as a glass transition point and hardness of a coating resin.
The method for producing an electrophotographic carrier according to (3) or (4).

(6) An electrophotographic carrier produced by the method according to any one of (1) to (5).

(7) An electrostatic latent image developer comprising the electrophotographic carrier according to the above (6), and a toner containing a binder resin and a colorant.

(8) forming a latent image on the latent image carrier;
Developing the latent image using a developer, transferring the developed toner image onto a transfer member, and heating and fixing the toner image on the transfer member. An image forming method using the electrostatic latent image developer according to the above (7).

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
The core material used in the present invention has an average particle size of 10 to 150 μm.
m, a magnetic metal powder such as iron, copper, nickel, and cobalt; a magnetic oxide powder such as magnetite and ferrite; and a magnetic material dispersed resin powder obtained by dispersing magnetic fine particles in a binder resin. .

The silane coupling agent used in the present invention includes 3-chloropropylmethyldimethoxysilane,
Chloropropyltrimethoxysilane chlorosilane, β- (3,4 epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane epoxy silane, N-β (aminoethyl) γ
-Aminopropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane,
amino-based silane of γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, vinyltrichlorosilane, vinyltris (βmethoxyethoxy) silane, vinyltriethoxysilane, vinyl-based silane of vinyltrimethoxysilane, Acrylic silane such as γ-methacryloxypropyltrimethoxysilane can be used. The amount of the silane coupling agent is 0.01 to 20 parts by weight based on 100 parts by weight of the core material.
Preferably it is 0.1 to 10 parts by weight.

The photoinitiator used in the present invention includes N, N
Those having a -dialkyldithiocarbamate group are preferred, and a diethyldithiocarbamate group is particularly preferred in view of the stability of the product. Also, 4-dimethylaminobenzoic acid, p-azidobenzoic acid, p-azidobenzaldehyde, p-sulfonylazidobenzoic acid, m-sulfonylazidobenzoic acid, p-azidocinnamic acid, p-azido-α-cyanocinnamic acid, It is also possible to use the above-mentioned photoinitiator having a polycondensation group such as cinnamic acid, cinnamylidene acetic acid, α-cyanocinnamylidene acetic acid and the like, but not limited thereto.

The method for introducing a photoreactive group of the present invention includes:
After treating the core material with a silane coupling agent having a reactive group that chemically bonds to the organic material, it is chemically bonded to the photoinitiator, or a photoinitiator containing a polycondensation group such as acid chloride is directly bonded to the core material. The core material can be obtained by chemically bonding and introducing a photoreactive group. It is also possible to obtain a core material by directly adsorbing a photoinitiator or a material obtained by dispersing / bonding the photoinitiator material with a core material and introducing a photoreactive group into the core material.

This photoreactive group-introduced carrier is prepared by coating a monomer component that undergoes radical polymerization with the photoreactive group in an organic solvent or water to prepare a coating solution, and using a high-pressure mercury lamp or the like under an inert gas stream. Radical polymerization can be easily performed by contacting the carrier with the coating solution while irradiating light having the above wavelength, and a resin layer can be formed on the surface of the carrier core material. In addition, if necessary, after forming the resin layer, a surface treatment may be performed by a mechanochemical treatment method in which heat treatment or mechanical stirring is performed to form a resin layer having a smooth surface. The surface treatment conditions are not particularly limited, for example, at a melting temperature of the resin or less,
Heat treatment is performed at the highest possible temperature in the presence of vibration, impact and / or shear. Examples of the processing apparatus include a rotary kiln, a vibrating fluidized-drying apparatus, an agromaster, a mechanofusion, a mermelizer, a spira coater, and a universal mixing stirrer.

According to the production method of the present invention, the coated state can be easily adjusted by controlling the amount of photoreactive group introduced to the surface of the carrier core material, the reaction conditions with the monomer component, and the like. Also, when using a carrier into which a chemically bonded photoreactive group is introduced, even if a water-soluble resin is used as the coating resin, there is no peeling due to a change in humidity,
The selection range of the coating resin can be expanded.

In the carrier manufacturing method of the present invention, the monomer components that radically polymerize with the photoreactive group and impart a negative charge to the toner include acrylamide, methacrylamide, N-methylacrylamide, N-ethylacrylamide, N-ethylacrylamide, Ethyl methacrylamide, N-dimethylacrylamide, N-dimethylmethacrylamide, N-diethylacrylamide, N-isopropylacrylamide, N-isopropylmethacrylamide, Nn-propylacrylamide, Nn-propylmethacrylamide, N-dimethylamino Propylacrylamide, N-
Acryloylpyridine, N-methacryloylpyridine,
N-acryloylpiperidine, N-methacryloylpiperidine, N-acryloylmorpholine, Nn-propylacrylamide, Nn-propylmethacrylamide, N-isopropylacrylamide, N-isopropylmethacrylamide, N-ethylacrylamide, N-
Examples thereof include, but are not limited to, diethylacrylamide, N-dimethylmethacrylamide, N-acryloylpyridine, and the like. These can be used alone or in combination of two or more.

In the method for producing a carrier according to the present invention, acrylic acid, methacrylic acid, vinyl sulfonic acid, styrene sulfonic acid, etc. are used as the monomer component which radically polymerizes with the photoreactive group to impart a positive charge to the toner. However, the present invention is not limited to these. These can be used alone or in combination of two or more.

Examples of the fluorine-containing monomer which is copolymerized with the radical-polymerizable monomer component and improves surface contamination resistance include fluorinated alkyl acrylates and fluorinated alkyl methacrylates.
1.1-dihydroperfluoroethyl, 1,1-dihydroperfluoropropyl, 1,1-dihydroperfluorohexyl, 1,1-dihydroperfluorooctyl, 1,1-
Dihydroperfluorodecyl, 1,1-dihydroperfluorolauryl, 1,1,2,2-tetrahydroperfluorobutyl, 1,1,2,2-tetrahydroperfluorooctyl, 1,1,2,2-tetrahydroper Fluorodecyl, 1,1,2,2-tetrahydroperfluorolauryl, 1,1,2,2-tetrahydroperfluorostearyl, 2,2,3,3-tetrafluoropropyl, 2,2
3,3,4,4-hexafluorobutyl, 1,1, ω-trihydroperfluorooctyl, 1,1,1,3,3,3
-Hexafluoro-2-chloropropyl, 3-perfluorononyl-2-acetylpropyl, 3-perfluorolauryl-2-acetylpropyl, N-perfluorohexylsulfonyl-N-methylaminoethyl, N-perfluorohexylsulfonyl- N-butylaminoethyl, N-perfluorooctylsulfonyl-N-methylaminoethyl,
N-perfluorooctylsulfonyl-N-ethylaminoethyl, N-perfluorooctylsulfonyl-N-butylaminoethyl, N-perfluorodecylsulfonyl-N
-Methylaminoethyl, N-perfluorodecylsulfonyl-N-ethylaminoethyl, N-perfluorolaurylsulfonyl-N-methylaminoethyl, N-perfluorolaurylsulfonyl-N-ethylaminoethyl, N-perfluorolaurylsulfonyl —N-butylaminoethyl and the like can be mentioned, and these can be used alone or in combination of two or more.

Styrene, methyl styrene, dimethyl styrene, trimethyl styrene, ethyl styrene, diethyl styrene are copolymerized with the above-mentioned radically polymerizable monomer components to control physical properties such as the glass transition point and resin hardness of the resin layer. Styrene, triethylstyrene, propylstyrene, butylstyrene, hexylstyrene,
Styrene derivatives such as heptylstyrene, octylstyrene, nitrostyrene, bromostyrene, acetylstyrene, etc., methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 2-hydroxy Ethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth)
Acrylic ester derivatives such as acrylate and methacrylic ester derivatives can be mentioned, and these can be used alone or in combination of two or more.

The glass transition point of the carrier coating resin layer of the present invention is suitably 50 ° C. or higher, preferably 70 ° C. or higher.
The upper limit is preferably about 200 ° C. Further, the type and content of the monomer forming the coating resin layer are selected and determined in consideration of charging design, durability, environmental stability, surface contamination resistance, and the like. The amount of the resin layer to be radically polymerized with the photoreactive group on the carrier core material of the present invention is 0.1 to 10.0% by weight, preferably 0.5 to 8.0% by weight based on the core material. Is appropriate. Also,
The thickness of the resin layer is suitably in the range of 0.1 to 10 μm.

The toner used together with the electrophotographic carrier of the present invention is most preferably a color toner. As the binder resin for the toner, a styrene / acrylic resin, a polyester resin, an epoxy resin, a polyurethane resin, a polyamide resin, a cellulose resin, or the like can be used alone or in combination.

As the colorant to be mixed with the toner, organic pigments, dyes, magnetic powders, carbon black and the like used for printing can be used. If necessary, components such as a charge control agent, an anti-offset agent such as a wax, and an anti-coloring agent can be added to the toner in addition to the colorant.

[0032]

The present invention will be described in detail with reference to the following examples. (Example 1) 100 parts by weight of a carrier core material composed of Cu-Zn-based ferrite particles having an average particle diameter of 50 µm,
1 part by weight of chloropropyltrimethoxysilane was stirred and contacted in methanol for 2 hours, allowed to adsorb on the surface of the carrier core material, and then filtered to obtain a carrier core material treated with 3-chloropropyltrimethoxysilane. The treated carrier core material was heat-treated at 120 ° C. for 6 hours to chemically bond the adsorbed 3-chloropropyltrimethoxysilane with the carrier core material. From the analysis result of the chlorine element, the coverage of the carrier core material surface with the above-mentioned 3-chloropropyltrimethoxysilane was 70%.

Next, 1 kg of carrier core material treated with 3-chloropropyltrimethoxysilane and 0.5 g of sodium N, N-diethyldithiocarbamate were added to 1 liter of dimethylformamide, and reacted at 60 ° C. for 24 hours with stirring. . After the reaction, the solution was collected by filtration, washed with distilled water to remove NaCl generated during the reaction, and dried at room temperature in vacuo to obtain a carrier core material having a photoreactive group introduced therein. After the reaction,
According to the analysis result of the chlorine element, almost 100% of sodium N, N-diethyldithiocarbamate reacted.

Example 2 200 g of the photoreactive group-introduced carrier core material prepared in Example 1 and 6.5 g of a styrene monomer
(80 mol%) and 1.5 g (20 mol%) of a dimethylacrylamide monomer were added to 300 g of a toluene solvent, and while irradiating with light using an external irradiation type 100 watt high pressure mercury lamp in an inert gas stream, The reaction was carried out by stirring at 30 ° C. for 24 hours. After completion of the reaction, the mixture was collected by filtration, washed with toluene to remove unreacted substances, put into stirred methanol and collected again by filtration, dried in vacuo, and sieved with a 75 μm sieve to remove aggregates. A resin-coated carrier was obtained.

When the obtained resin-coated carrier was visually observed, no aggregate was found on the sieve. As a result of weight measurement, the resin coating amount on the photoreactive group-introduced carrier core material was 2.6% by weight. Observation with a scanning electron microscope confirmed that the resin was uniformly and completely covered with the resin. As a result of elemental analysis, the copolymerization ratio was almost as charged.

Example 3 The resin-coated carrier prepared in Example 2 was heated to 95 ° C. with a surface reformer (V-dryer, manufactured by Chuo Kakoki Co., Ltd.) to smooth the unevenness of the resin coating layer. Then, the treatment was performed for 2 hours while applying vibration. When the obtained carrier was observed with a scanning electron microscope, it was confirmed that the carrier was uniformly and completely covered with the resin and the surface was smooth. As a result of elemental analysis, the copolymerization ratio was almost as charged.

Example 4 200 g of the photoreactive group-introduced carrier core material prepared in Example 1, 1.5 g (15 mol%) of butyl methacrylate monomer, and 6.5 g of N-isopropylacrylamide monomer ( (85 mol%) in 300 g of a solvent, tetrahydrofuran, and reacted by stirring at 30 ° C. for 24 hours in an inert gas stream while irradiating with light using a high-pressure mercury lamp of an external irradiation type of 100 watts. After completion of the reaction, the reaction mixture is collected by filtration, put into stirred methanol to wash unreacted substances, collected by filtration again, dried in vacuum, sieved with a 75 μm sieve, and the aggregate is removed to coat the resin. Got a career.

When the obtained resin-coated carrier was visually observed, no aggregate was found on the sieve. As a result of weight measurement, the resin coating amount with respect to the photoreactive group-introduced carrier core material was 2.4% by weight. Observation with a scanning electron microscope confirmed that the resin was uniformly and completely covered with the resin. As a result of elemental analysis, the copolymerization ratio was almost as charged. Since the coating resin is a water-soluble resin, washing with cold distilled water was attempted to confirm the presence or absence of elution, but no elution was observed. This is because the water-soluble binder resin is chemically bonded to the carrier core material.

(Example 5) 200 g of the photoreactive group-introduced carrier core material prepared in Example 1 and 8 g of acrylamide were added to 300 g of distilled water, and an external irradiation type high pressure mercury lamp of 100 watts was applied in an inert gas stream. The mixture was stirred at 30 ° C. for 24 hours while irradiating light with the, and reacted. After the reaction,
After being collected by filtration, the unreacted product was washed with distilled water, collected again by filtration, dried in vacuum, and sieved with a 75 μm sieve to remove aggregates, thereby obtaining a resin-coated carrier.

When the obtained resin-coated carrier was visually observed, no aggregate was found on the sieve. As a result of the weight measurement, the resin coating amount on the photoreactive group-introduced carrier core material was 3.4% by weight. Observation with a scanning electron microscope confirmed that the resin was uniformly and completely covered with the resin. As a result of elemental analysis, the copolymerization ratio was almost as charged. Since the coating resin was a water-soluble resin, washing with distilled water was attempted to confirm the presence or absence of elution, but no elution was observed. This is because the water-soluble binder resin is chemically bonded to the carrier core material.

Comparative Example 1 97.5 g of styrene monomer
(80 mol%) and dimethylacrylamide monomer 2
2.5 g (20 mol%) were dissolved in 280 g of a solvent toluene, and a polymerization initiator azobisisobutyronitrile 1.8 was obtained.
g (1 mol%), and the mixture was reacted at 60 ° C. for 48 hours in a nitrogen stream. After completion of the reaction, reprecipitation with methanol was performed to obtain 85.6 g of a random copolymer. When the molecular weight of this copolymer was measured by gel permeation chromatography, the weight average molecular weight (Mw) was 350.
00.

With respect to 100 parts by weight of a core material of a carrier composed of Cu—Zn ferrite particles having an average particle diameter of 50 μm, the above-mentioned copolymer solution was added so that the solid content in the solution became 2.6 parts by weight. Add and mix in a 1 L small kneader with heated hitter at 50 ° C. for 30 minutes, then raise to 120 ° C. and stir for another 40 minutes, then turn off the heater,
It was cooled while stirring to form a resin coating layer. afterwards,
After heat treatment at 100 ° C. for 2 hours, the mixture was sieved with a 75 μm sieve to remove aggregates, thereby obtaining a resin-coated carrier of 53% by weight (% by weight based on the carrier before sieving). Observation of the obtained resin-coated carrier with a scanning electron microscope revealed that there was uneven coating of the resin, and the carrier core material was exposed in some places.

Comparative Example 2 A 10% by weight toluene solution of the styrene / dimethylacrylamide random copolymer obtained in Comparative Example 1 was prepared to prepare a carrier coating solution. Using a fluidized bed coating apparatus, Cu-Z having an average particle size of 50 μm was used.
The carrier coating solution was sprayed on the core material of the carrier composed of n-type ferrite particles to form a resin coating layer. Spray conditions at this time were: air pressure to the spray nozzle of 2.2 kg / cm ² , flow rate of 30 liter / min,
The supply rate of the carrier coating solution was 8.0 ml / min. Thereafter, the mixture was sieved with a 75 μm sieve to remove aggregates, thereby obtaining a resin-coated carrier of 72% by weight (% by weight based on the carrier before sieving). Observation of the obtained resin-coated carrier with a scanning electron microscope revealed that there was uneven coating of the resin, and the carrier core material was exposed in some places.

Comparative Example 3 22.5 g (15 mol%) of a butyl methacrylate monomer and 97.5 g (85 mol%) of an N-isopropylacrylamide monomer were dissolved in 280 g of a solvent, tetrahydrofuran, and a polymerization initiator was dissolved. 1.8 g (1 mol%) of azobisisobutyronitrile
Was added, and the reaction was carried out at 60 ° C. for 48 hours in a nitrogen stream. After completion of the reaction, reprecipitation with methanol was performed to obtain 85.6 g of a random copolymer. When the molecular weight of this copolymer was measured by gel permeation chromatography, the weight average molecular weight (Mw) was 43,000.

The above copolymer solution was added to 100 parts by weight of a core material of a carrier made of Cu—Zn ferrite particles having an average particle diameter of 50 μm so that the solid content in the solution was 2.6 parts by weight. In a 1L small kneader equipped with a heating hitter, mix at 50 ° C. for 30 minutes, then raise to 120 ° C., stir for 40 minutes, turn off the heater, cool while stirring, and sieve through a 75 μm sieve. The aggregates were removed to obtain 57% by weight (% by weight based on the carrier before sieving) of the resin-coated carrier.

When the obtained resin-coated carrier was observed with a scanning electron microscope, it was found that the resin coating was uneven and the carrier core material was exposed in some places. Further, in order to confirm elution from a place where the coating resin is a water-soluble resin, washing was performed with cold distilled water, and as a result, the resin layer was eluted. This indicates that the coating resin layer may melt during use due to changes in temperature and humidity, and the reliability of the developer is low and cannot be put to practical use.

(Preparation of Toner for Measurement) Example of Resin Production (hereinafter abbreviated as “Resin-1”) Polyoxyethylene (2,2) -2,2-bis (4-hydroxyphenyl) propane: 1.3 Mol (300) polyoxypropylene (2,2) -2,2-bis (4-hydroxyphenyl) propane: 1.0 mol (326) terephthalic acid: 2.3 mol (166)

The above raw material compound was placed in a glass two-liter four-necked flask, and a stirring rod, a condenser, a nitrogen gas inlet tube, and a thermometer were set, and the mixture was set in a mantle heater. Next, after the inside of the reaction vessel was replaced with nitrogen gas, 1 g of dibutyl oxide was added, and the reaction was carried out in a nitrogen stream while heating with a mantle heater at a normal pressure of about 150 ° C. in the first half, and under a reduced pressure of 220 ° C. in the second half. Reacted. After the completion of the reaction, the resultant was cooled to room temperature. The glass transition temperature Tg of this resin is 6
4 ° C.

Production of Cyan Flushing Pigment 100 parts by weight of the above toner resin Cyan pigment (CI Pigment Blue 15: 3) water-containing paste (water content in water-containing paste = 30 wt%) 62 parts by weight The water in the pigment-containing paste was replaced with polyester A while melting and kneading with water to remove water, and a cyan flushing pigment having a pigment content of 30 wt% was obtained.

Preparation of Magenta Flushing Pigment The above cyan pigment was replaced with a magenta pigment (CI Pigment Red 57: 1) water-containing paste (water content in water-containing paste = 30 wt%) in the same manner as the above-mentioned cyan flushing pigment. Thus, a magenta flushing pigment having a pigment content of 30 wt% was obtained.

Production of Yellow Flushing Pigment The above-mentioned cyan pigment was replaced with a yellow pigment (CI Pigment Yellow 17) hydrated paste (water content in the hydrated paste = 30 wt%) in the same manner as the above-mentioned cyan flushing pigment. A yellow flushing pigment having a pigment content of 30% by weight was obtained.

Production of Black Toner 4 parts of carbon black (primary particle diameter: 48 nm) and 96 parts of "Resin-1" are melt-kneaded with a Banbury mixer, cooled, pulverized with a jet type pulverizer, and further classified with a classifier. A black toner was obtained with a uniform particle size distribution. The particle size of the obtained black toner was measured using a Coulter counter.
Volume average diameter d ₅₀ = 7.2 μm, volume particle size distribution d ₁₆ / d ₈₄
= 1.7. 0.7 parts of silica fine powder (R812, manufactured by Nippon Aerosil Co., Ltd.) as an external additive and 0.7 parts of hydrophobic titanium oxide (manufactured by Teica, MT-100S) are added to 100 parts of the toner. Were added and mixed with a Henschel mixer to obtain an externally added toner.

Preparation of Cyan Toner 14 parts of cyan flushing pigment and 86 of "Resin-1"
After preliminary mixing, the mixture was melt-kneaded with a Banbury mixer, cooled, pulverized and classified by a jet mill, and classified into a pigment-containing 4 wt% volume average diameter d ₅₀ = 7.2 μm and a volume particle size distribution d ₁₆ / D ₈₄ = 1.6 cyan toner was prepared. To the above toner, silica fine powder (R812, manufactured by Nippon Aerosil Co., Ltd.) as an external additive was added in an amount of 0.7 part per 100 parts of toner, and hydrophobic titanium oxide (manufactured by Teica, MT-1).
(00S) was added and mixed with a Henschel mixer to obtain an externally added toner.

[0054]Production of magenta toner 14 parts of magenta flushing pigment and "Resin-1" 8
After premixing 6 parts, melt with Banbury mixer
Knead, cool, jet mill crush, classify and pigment
Volume average diameter d with a content of 4 wt%₅₀= 7.2 μm, volume granules
Degree distribution d₁₆/ D ₈₄= 1.6 magenta toner
Was. Silica fine powder (Japan
Aerosil R812) to 100 parts of toner
0.7 parts, hydrophobic titanium oxide (manufactured by Teica, MT-1
00S) and mix with Henschel mixer
Thus, an externally added toner was obtained.

Production of Yellow Toner 16.7 parts of yellow flushing pigment, "Resin-1"
Was premixed, melt-kneaded with a Banbury mixer, cooled, jet-milled, and classified to obtain a pigment-containing 4 wt% volume average diameter d ₅₀ = 7.2 μm.
m, a yellow toner having a volume particle size distribution of d ₁₆ / d ₈₄ = 1.6 was prepared. To the above toner, silica fine powder (R812, manufactured by Nippon Aerosil Co., Ltd.) as an external additive was added to toner 100.
0.7 parts by weight, hydrophobic titanium oxide (manufactured by Teica,
MT-100S) was added and mixed with a Henschel mixer to obtain an externally added toner.

Preparation of Developer 10 parts by weight of each color toner described above and 100 parts by weight of the carriers of Examples 2 to 4 and Comparative Examples 1 and 2 were mixed with a V blender to prepare a color developer. Made A
color digital full color machine (A COLOR 6
Fog, solid image density, halftone, reproducibility of line image, carrier adhesion on image, toner scattering, image quality The sensory evaluation of maintainability was performed.

[0057]

[Table 1]

(Evaluation) When the resin-coated carriers obtained in Examples 2 to 5 were used, the density of the solid image was high, there was no fog, and the reproducibility of the halftone portion and the line image was good. In addition, no carrier adhered to the image, and no toner was scattered during development. In particular, in Example 2 in which the resin coating layer was smoothed, the reproducibility of the halftone portion and the line image was even better than in the other examples.

On the other hand, in Comparative Example 1, although the density of the solid image was high, the fog was remarkable, the roughness of the halftone portion was remarkable, and the line image was poor. Further, carrier adhesion on the image was remarkable, and toner scattering was also remarkable. In Comparative Example 2, although the density of the solid image was high, fogging occurred, and further, roughness in the halftone portion and a defective portion in the line image were slightly generated. In addition, carrier adhesion to the image and toner scattering slightly occurred. In Comparative Example 3, although the density of the solid image was high as in Comparative Example 1, the fog was remarkable, the roughness of the halftone portion and the defective portion of the line image were remarkable, and the carrier adhesion to the image was further reduced. The toner scattering was remarkable.

[0060]

According to the present invention, by adopting the above structure, a uniform coating layer is formed without aggregation of the carrier, the selection range of the coating resin is expanded, the coating state is controlled, and the reliability is improved. Thus, an electrophotographic carrier can be provided, and by using this carrier, an image having a high density and no fog can be stably obtained.

Claims (4)

[Claims] 1. A process for introducing a photoreactive group onto a core material, and a step of forming a resin coating layer by radically polymerizing a monomer using the photoreactive group as a reaction point. Carrier manufacturing method. 2. An electrophotographic carrier produced by the method according to claim 1. 3. An electrophotographic carrier according to claim 2,
An electrostatic latent image developer containing a binder resin and a toner containing a colorant. 4. A step of forming a latent image on a latent image carrier, a step of developing the latent image using a developer, a step of transferring the developed toner image onto a transfer body, and a step of An image forming method comprising a step of heating and fixing the toner image of
An image forming method, comprising using the electrostatic latent image developer according to claim 3 as the developer.