JPH07319218A - Electrostatic charge image developing carrier, its production and developer - Google Patents

Abstract

PURPOSE:To provide an electrostatic charge image developing carrier having excellent electrifying performance and its production method to maintain high electric resistance of the carrier by forming a coating layer of a thin layer having high film strength at high coating rate. CONSTITUTION:The electrostatic charge image developing carrier is produced by treating the surface of core particles with an amino group-contg. silane coupling agent, applying a resin soln. on the particles, and drying. In this method, the solvent is removed under pressure of 0.66-1.6 times as much as the saturated vapor pressure of the solvent in the resin soln. at the drying temp., and then the resin layer is dried under pressure of 1/100 to 1/20 times as much as the saturated vapor pressure. Thus, the obtd. carrier has 85-95% coating rate of the coating layer and 0.01-0.5mum average layer thickness of the coating layer. When 10<3.5>V/cm voltage is applied on the carrier, the resistance of the carrier is 1.5X10<9> to 3.0X10<10>OMEGAcm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic charge image developing carrier used for developing an electrostatic latent image formed by an electrophotographic method, an electrostatic recording method or the like with a two-component developer, and a method for producing the carrier. And an electrostatic image developer.

[0002]

2. Description of the Related Art A method of visualizing image information through an electrostatic charge image such as an electrophotographic method is currently used in various fields. In the electrophotographic method, an electrostatic latent image is formed on a photosensitive member by a charging and exposing process, the electrostatic latent image is developed with a developer containing toner, and then transferred and fixed to be visualized. The developer used here includes a two-component developer composed of a toner and a carrier and a one-component developer such as a magnetic toner which is used alone as a toner. In the two-component developer, the carrier is a developer. It is widely used at the present time because it has functions such as good controllability because it is divided into functions such as stirring, carrying, and charging and is separated as a developer. In particular,
A developer using a resin-coated carrier has excellent charge controllability, and is relatively easy to improve in environmental dependency and stability over time. Further, as a developing method, a cascade method or the like has been used in the old days, but at present, a magnetic brush method using a magnetic roll as a developer conveying unit is mainly used.

In the magnetic brush method using a two-component developer,
There are problems such as a decrease in image density due to charge deterioration of the developer, a remarkable stain on the background portion, image roughness and carrier consumption due to carrier adhesion to the image, and further uneven image density. The mechanism of carrier attachment to the image is
When the carrier resistance decreases, the induced charge is injected into the image area to attach the carrier, or the upper limit control of the charge amount of the carrier is insufficient, and the charge amount of the carrier after development becomes excessive. It is considered that the carrier adheres to the edge portion.

In recent years, in the two-component developer, the diameter of the carrier is further reduced for the purpose of improving the image quality, the self-weight of the carrier is reduced, and the adhesion of the carrier becomes more and more a problem.
The trend of the developing system is to increase the speed, and the stress received by the developer inside the machine is further increased, and the reliability is often lowered accordingly. Therefore, a coated carrier coated with a resin has been used in order to adjust the resistance of the carrier and control the charge amount of the carrier. Regarding the resin coating method, a method of dissolving the resin in a solvent and then coating and drying the surface of the magnetic core particles is generally used.

Regarding a carrier of a two-component developer, a fluorine-containing resin is used as a core particle in order to reduce the surface energy of the carrier surface to prevent contamination of the carrier surface or to harden the carrier surface to prevent surface abrasion. Is also proposed, and in order to improve the adhesion of the silicone resin to the core particles, it has been proposed to pretreat it with a coupling agent (see JP-A-60-19156). .

However, since the silicone resin is located in the middle of the charging series, it alone gives only weak charging. Therefore, after coating a silicone resin having a high hardness and then a silicone resin having a low hardness, the carrier has an electrical resistivity of 5.0 × 10 ⁹ to 5.0 × 10 ¹¹ Ωcm, and the electrical resistivity of only the inner layer. A carrier having 0.2 to 0.5 times the carrier is proposed (see Japanese Patent Laid-Open No. 263052/1993), but the inner layer itself is a coating layer having a charging function, and the layer thickness of the entire coating layer is Since it became thick, the charging ability was not sufficient.

In addition, surface contamination resistance, environmental dependence of charging,
As a carrier having improved charge rising property and charge exchange property, there has been proposed a carrier using a silane coupling agent in the inner layer and a fluororesin in the outer layer (Japanese Patent Laid-Open Nos. 4-198946 and 5). However, since the coating layer cannot be thinned and a high coverage cannot be obtained, the charging ability is not always sufficient.

[0008]

Therefore, the present invention is intended to solve the above problems and provide a carrier for developing an electrostatic charge image having the following features, a method for producing the carrier, and an electrostatic charge image developer. Is. To reduce the amount of coating resin on the carrier, reduce the thickness of the coating layer, and increase the coverage to maintain semi-insulating properties and improve the charging ability. To lower the surface energy of the carrier coating layer, prevent toner adhesion, and maintain charge stability. Improve image quality maintenance by suppressing charge fluctuations due to environmental fluctuations. To extend the life of the carrier by improving the adhesion of the coating resin to the core particles. To provide excellent image quality for reproducing solid black and fine lines. Prevents carrier scattering by increasing electrical resistance. When the toner is added, the carrier and the toner have good mixing properties, and a uniform charge amount can be easily obtained. The surface of the carrier is smooth and there is little toner contamination.

[0009]

Means for Solving the Problems As a result of intensive studies for solving the above-mentioned problems, the present inventors have found that by devising conditions for forming a resin coating layer, the film strength is high and the electric resistance is high. The present invention has been completed by succeeding in manufacturing a carrier having excellent charging ability. Specific embodiments of the present invention are as follows.

(1) In a carrier for developing an electrostatic charge image having a resin coating layer on core particles treated with an amino group-containing silane coupling agent, the coating layer has a coverage of 85 to 95.
%, And the average layer thickness of the coating layer is 0.01 to 0.
The electric resistance is in the range of 5 μm and the electric resistance when a voltage of 10 ^3.5 V / cm is applied to the carrier is 1.5 × 10 ^{9 to} 3.0.
A carrier for developing an electrostatic charge image, which is in the range of × 10 ¹⁰ Ωcm.

(2) A coating layer containing a fluorinated alkyl (meth) acrylate-based copolymer is provided on the surface of core particles treated with an amino group-containing silane coupling agent. Carrier for electrostatic image development.

(3) In the method for producing a carrier for developing an electrostatic charge image, the surface of a core particle is treated with an amino group-containing silane coupling agent, and then the surface of the core particle is coated with a resin solution and dried. After removing the solvent under the pressure of 0.66 to 1.6 times the saturated vapor pressure of the solvent of the resin solution at the drying temperature in the coating step, 1/1000 to the saturated vapor pressure of
The above characterized by being dried under a pressure of 1/20 times
(1) A method for producing the carrier for developing an electrostatic charge image as described above.

(4) An electrostatic charge image developer containing the carrier for developing an electrostatic charge image according to (1) or (2) above and a toner using a polyester resin as a binder resin.

[0014]

According to the present invention, in the step of coating the resin solution on the core particles treated with the amino group-containing silane coupling agent, the core particles are dried under almost the same pressure as the saturated vapor pressure of the solvent to gradually remove the solvent. Then, by drying under high vacuum, it is possible to form a coating layer having a high film strength and a thin layer thickness with a high coating rate, and as a result, it is possible to maintain a high electric resistance of the carrier and improve the charging ability. It succeeded in improving and completed the present invention.

In the carrier for developing an electrostatic charge image of the present invention, the coverage of the resin coating layer is 85 to 95%, preferably 9%.
A range of 0 to 95% is suitable. If the coverage is less than 85%, the charge amount becomes large when the replenishment toner is mixed,
If it exceeds 5%, the action of the lower layer becomes low, so that there is a disadvantage that a high charge amount cannot be maintained.

The average layer thickness of the coating layer is 0.01-0.
A range of 5 μm, preferably 0.3-0.5 μm is suitable. If the average layer thickness of the coating layer is less than 0.01 μm, the charge amount tends to be higher than a predetermined amount and the charge distribution is widened. If it exceeds 0.5 μm, a toner having a sufficient charge amount cannot be obtained. And the inconvenience occurs.

The electric resistance when a voltage of 10 ^3.5 V / cm is applied to the carrier is 1.5 × 10 ^{9 to} 3.0 ×.
10 ¹⁰ Ωcm, preferably 5.0 × 10 ^{9 to} 2.5 × 1
A range of 0 ¹⁰ Ωcm is suitable. 1.5 × 10 ⁹ Ωcm
When it is below 3, the charge amount of the carrier tends to be high, and 3.
If it exceeds 0 × 10 ¹⁰ Ωcm, there is a problem that toner scattering occurs.

Further, after treating the surface of the core particles with a silane coupling agent containing an amino group, the surface of the core particles is coated with a resin solution and dried to coat the carrier, in the method for producing a carrier for developing an electrostatic charge image, a solvent is used. The pressure of the first step for removal is 0.66 to 1.6 times, preferably 0.7 to 1.4 times, more preferably 0.8 to 1.4 times the saturated vapor pressure of the solvent of the resin solution at the drying temperature. A range of 1.2 times is suitable.
When it is less than 0.66 times, the surface of the coating layer is dried quickly and the surface is solidified early, so that the solvent is likely to remain inside. If the solvent remains, the strength of the coating layer decreases, which is not preferable. If it exceeds 1.6 times, the solvent can hardly be removed, and the solvent remains in the second stage.

The pressure of the second stage for finish drying is 1/1000 to 1/20 times the saturated vapor pressure, preferably 1
/ 1000 to 1/40 times, more preferably 1/1000
The range of up to 1/100 is suitable. If it exceeds 1/20 times, the resin coating rate decreases and the desired coating layer thickness cannot be obtained. Further, when it is less than 1/1000 times, the vacuum becomes too high, and the burden of securing the performance of the machine is large, which is a problem in terms of cost.

The amino group-containing silane coupling agent used in the present invention forms a three-dimensional network structure by a dehydration condensation reaction and becomes insoluble in a solvent. Specific examples thereof include the following. NH ₂ CH ₂ CH ₂ CH ₂ Si (OR) ₃ NH ₂ CONHCH ₂ CH ₂ CH ₂ Si (OR) ₃ NH ₂ CH ₂ CH ₂ NHCH ₂ CH ₂ CH ₂ Si (O
R) ₃ C ₆ H ₅ NHCH ₂ CH ₂ Si (OR) ₃ (In the formula, R represents a methyl group or an ethyl group.)

Examples of the coating resin used in the present invention include fluorinated alkyl (meth) acrylate copolymers, silicone resins, polyethylene resins and polypropylene resins. In addition, in order to control the adhesion of the coating resin to the core particles treated with the coupling agent and the releasability of the surface layer, a resin other than the above resins can be used together. When the fluorinated alkyl (meth) acrylate copolymer is used, it is preferable to use another (meth) acrylic polymer, styrene (meth) acrylic copolymer or the like in the state of polymer blend. As the structure of the fluorinated alkylate, a graft structure or a block structure is preferable because the adhesion and the releasability of the surface layer can be precisely controlled.

The amount of the fluorinated alkyl (meth) acrylate monomer in the fluorinated alkyl (meth) acrylate copolymer used in the present invention is preferably in the range of 30 to 60% by weight. When a blend of a fluorinated alkyl (meth) acrylate copolymer and another polymer is used, the mixing ratio of the copolymer is 40 to 70% by weight.
The range is suitable.

Examples of the fluorinated alkyl (meth) acrylate constituting the fluorinated alkyl (meth) acrylate copolymer used in the present invention include ester compounds of (meth) acrylic acid and the following compounds.
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-trihydroperfluorohexyl, 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-perfluorodecylsulfonyl-N-butylaminoethyl, N-perfluorolaurylsulfonyl-N-methylaminoethyl, N-perfluorolaurylsulfonyl-N-ethylaminoethyl, N-perfluorolaurylsulfonyl- N-butylaminoethyl.

Examples of the monomer component copolymerizable with the fluorinated alkyl (meth) acrylate include the following. Styrene, methyl styrene, dimethyl styrene, trimethyl styrene, ethyl styrene, diethyl styrene, triethyl styrene, propyl styrene,
Alkyl styrenes such as butyl styrene, hexyl styrene, heptyl styrene, octyl styrene; halogenated styrenes such as fluorostyrene, chlorostyrene, bromostyrene, dibromostyrene, iodostyrene; styrene-based monomers such as nitrostyrene, acetylstyrene, methoxystyrene; Addition-polymerizable unsaturated aliphatic monocarboxylic acids such as (meth) acrylic acid, α-ethyl (meth) acrylic acid, crotonic acid, α-methylcrotonic acid, α-ethylcrotonic acid, isocrotonic acid, tiglic acid, and ungeric acid An addition polymerizable unsaturated aliphatic dicarboxylic acid such as maleic acid, phthalic acid, itaconic acid, citraconic acid, mesaconic acid, glutaconic acid or dihydromuconic acid; an esterification product of the addition polymerizable unsaturated carboxylic acid and an alcohol, for example, methyl alcohol Alkyl alcohols such as ethyl alcohol, propyl alcohol, butyl alcohol, amyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, nonyl alcohol, dodecyl alcohol, tetradecyl alcohol, and hexadecyl alcohol, these alkyl alcohols are partially alkoxylated, Alkoxyalkyl alcohols such as methoxy alcohol, ethoxy alcohol, ethoxyethoxyethyl alcohol, methoxypropyl alcohol and ethoxypropyl alcohol, aralkyl alcohols such as benzyl alcohol, phenylethyl alcohol and phenylpropyl alcohol, alkenyl alcohols such as allyl alcohol and crotonyl alcohol An esterified product of (meth) acrylic acid Killesters, fumaric acid alkyl esters, maleic acid alkyl esters, etc .; amides or nitriles derived from the addition-polymerizable unsaturated carboxylic acids; aliphatic monoolefins such as ethylene, propylene, butene, isobutylene: vinyl chloride, vinyl bromide , Vinyl iodide, 1,2-dichloroethylene, 1,2-dibromoethylene, 1,2-diiodoethylene, isopropenyl chloride, isopropenyl bromide, allyl chloride, allyl bromide, vinylidene chloride, vinyl fluoride, fluorine Halogenated fatty acid olefins such as vinylidene chloride; 1,3-butadiene, 1,3-pentadiene, 2-
Methyl-1,3-butadiene, 2,3-dimethyl-1,
3-butadiene, 2,3-hexadiene, 3-methyl-
Conjugated diene-based aliphatic diolefins such as 2,4-hexadiene; 2-vinylpyridine, 4-vinylpyridine, 2-
Vinyl-6-methylpyridine, 2-vinyl-6-methylpyridine, 2-vinyl-5-methylpyridine, 4-butenylpyridine, 4-pentenylpyridine, N-vinylpiperidine, 4-vinylpiperidine, N-vinyldihydropyridine, N -Vinylpyrrole, 2-vinylpyrrole,
Examples of nitrogen-containing vinyl-based monomers such as N-vinylpyrrolidine, N-vinylpyrrolidine, 2-vinylpyrrolidine, N-vinyl-2-pyrrolidone, N-vinyl-2-piperidone and N-vinylcarbazole can be mentioned. These can be used alone or in combination of two or more.

The coating amount of the coating resin can be used in a total amount of 0.1 to 5.0% by weight based on the carrier. The coverage of the coating layer can be used in the range of 85 to 95%.

Examples of the core particles used in the present invention include iron powder, ferrite powder, and granulated magnetite. The core particles having an average particle size of about 20 to 60 μm can be used. If it is smaller than 20 μm, there may be a problem that the carrier flies on the photoreceptor,
When it is larger than 60 μm, there is a problem that the image quality is apt to deteriorate.

The carrier of the present invention is coated by coating a solution of a coating resin dissolved in a solvent on the core particles and then heating to distill off the solvent. For this coating operation, a heating type kneader,
A heating type Henschel mixer, a UM mixer, a planetary mixer, etc. can be used. The carrier of the present invention has an average particle size of 20 to 80 μm, particularly 20 to 70 μm.
A range of m is preferred.

The carrier of the present invention is mixed with a toner to prepare a toner.
Used as a component developer. The toner is a binder resin in which a colorant or the like is dispersed. The binder resin used for the toner includes styrenes such as styrene and parachlorostyrene; monoolefins such as ethylene, propylene, butylene and isobutylene. Vinyl esters such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl benzoate; methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, octyl (meth) acrylate, (meth ) Dodecyl acrylate, α-methylene aliphatic monocarboxylic acid esters such as phenyl (meth) acrylate; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl butyl ether; vinyl methyl ketone, vinyl hexyl ketone, vinyl isopropenyl Vinyl ketone such as ketone It can be exemplified homopolymers or copolymers and the like. In particular, typical binder resins include polystyrene, polyethylene, polypropylene, styrene-alkyl acrylate copolymer, styrene-alkyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-
Examples thereof include a butadiene copolymer and a styrene-maleic anhydride copolymer. In addition, polyester resin,
Examples thereof include polyurethane resin, epoxy resin, silicone resin, polyamide resin, modified rosin, and paraffin wax.

Colorants used in the toner include carbon black, aniline black, aniline blue, calcoil blue, chrome yellow, ultramarine blue, DuPont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, and lamp black. , Rose Bengal, etc. can be exemplified as typical ones.

As toner components other than the colorant, charge control agents such as salicylic acid metal salts, metal-containing azo compounds, nigrosine and quaternary ammonium salts; low molecular weight polypropylene,
Known components such as low molecular weight polyethylene and anti-offset agents such as wax can be added, and among them,
A low molecular weight polypropylene having a weight average molecular weight of 500 to 5000 is particularly effective.

To produce a toner, the above toner materials are blended and mixed by using a Banbury mixer, a kneader coder, a CM mixer, an extruder, etc., melt-kneaded, and pulverized and classified to obtain an average particle diameter of 30 μm or less,
In particular, it is preferable that the particle size is 3 to 20 μm.

Further, an external additive such as a fluidizing agent such as silica, titania, or alumina, a cleaning aid such as polystyrene fine particles, polymethylmethacrylate fine particles, polyvinylidene fluoride fine particles, or a transfer aid can be used. The hydrophobic particles having a primary average particle size of 5 to 30 nm are particularly effective as the fluidizing agent.

[0033]

EXAMPLES The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to these examples. The layer thickness of the coating layer of the carrier is the transmission electron microscope (TE
M) was photographed, the average value of the layer thickness was determined, and the coverage was calculated by taking a photograph with a scanning electron microscope (SEM) and analyzing the image data. The electric resistance of the carrier is
A carrier was filled between electrodes on a disk having a gap between the electrodes of 1 mm and a radius of 2.5 cm, and the load was measured at 100 g / cm ² .

Example 1 (Production of Carrier) Ferrite (average particle size: 50 μm)
(Made by Udertech) 100 parts by weight, silane coupling
Agent (γ-aminopropyltriethoxysilane) 0.1
Parts, methanol 20 parts by weight and water 0.02 parts by weight.
And heat medium temperature 1 with a 30 liter planetary mixer
After setting the temperature to 20 ° C. and stirring for 20 minutes, the degree of vacuum is 4.9 ×
10 ^Four20 minutes at Pa, and a vacuum degree of 8.2 × 10³
After drying at Pa for 20 minutes, cool and sieve with a 75 μm sieve.
Mining to obtain coated particles. Surface condition of the obtained coated particles
The state was examined by ESCA (X-ray fluorescence spectrometer)
Fe intensity of body particle component is small and exposed on the particle surface
A uniform film is formed from a small amount of Fe atoms.
I understand that.

Next, 100 parts by weight of the coated particles were added to 0.25 parts by weight of a fluorinated methacrylic resin (a perfluorooctylethylmethacrylate / methylmethacrylate copolymer manufactured by Soken Chemical Co., Ltd.) and a styrene-MMA copolymer (SANYO). Kasei Co., Ltd., dimethylaminoethyl methacrylate / styrene / methyl methacrylate copolymer) 0.25
Parts by weight and toluene (vapor pressure 3.5 × 10 ⁴ Pa) 10
After adding parts by weight, the heat medium temperature was set to 120 ° C. with a 30 liter planetary mixer, and after confirming that the temperature was 75 ° C., the contents were stirred for 5 minutes, and then the degree of vacuum was 5 × 10 ⁴ P.
a (1.4 times the vapor pressure of toluene) for 5 minutes, and further dried for 15 minutes at a vacuum degree of 100 Pa (2.8 × 10 ⁻³ times the vapor pressure of toluene), and then cooled, 7
A carrier was obtained by sieving with a 5 μm sieve. The average layer thickness of the coating layer of the obtained carrier was 0.46 μm, and the coating rate was 95%. The electric resistance of the carrier is 2.8.
It was × 10 ¹⁰ Ωcm.

(Production of Toner) Polyester Resin (DI
Toner particles having an average particle size of 7 μm were obtained by a kneading and pulverizing method using 97% by weight of C company and 3% by weight of carbon black (# 25, manufactured by Mitsubishi Kasei). To the toner particles, 0.01 part by weight of hydrophobic silica (R972 manufactured by Nippon Aerosil Co., Ltd.) was externally added.

Example 2 (Production of Carrier) 100 parts by weight of magnetite (manufactured by DIC) having an average particle size of 60 μm, 0.05 part by weight of a silane coupling agent (γ-aminopropyltriethoxysilane), 10 parts by weight of methanol. Parts and 0.01 part by weight of water were mixed to obtain a carrier in the same manner as in Example 1. When the surface state of the coated particles coated with the silane coupling agent was examined by a fluorescent X-ray analyzer, it was found that a uniform coating was formed with a small Fe intensity of the core particle component. The average layer thickness of the carrier coating layer was 0.42 μm, and the coverage was 90%. The electric resistance of the carrier was 1.7 × 10 ⁹ Ωcm.

Comparative Example 1 (Production of Carrier) In Example 1, the drying condition for coating the fluorinated methacrylic resin and the styrene-MMA copolymer was set to a vacuum degree of 5 × 10 ⁴ Pa (toluene vapor pressure). (1.4 times) for 5 minutes, then vacuum degree 41
1 at 00 Pa (0.12 times the vapor pressure of toluene)
A carrier was obtained in the same manner as in Example 1 except that drying was performed for 5 minutes. The average layer thickness of the coating layer of the obtained carrier was 0.52 μm, and the coating rate was 80%. The electric resistance of the carrier was 1.1 × 10 ⁹ Ωcm.

Comparative Example 2 (Production of Carrier) A carrier was obtained in the same manner as in Example 1 except that the first drying step was omitted. The average layer thickness of the obtained carrier coating layer is 0.60 μm.
m, the coverage was 50%. The electric resistance of the carrier was 5.4 × 10 ⁶ Ωcm.

Comparative Example 3 (Production of Carrier) In Example 1, when a carrier was produced by omitting the second drying step, the drying was insufficient and carrier agglomeration occurred to obtain particles. could not. The same result was obtained even when the time of the first drying step was extended.

Comparative Example 4 (Production of Carrier) In Example 2, the drying condition for coating the fluorine-containing methacrylic resin and the styrene-MMA copolymer was set to a vacuum degree of 5 × 10 ⁴ Pa (toluene vapor pressure). (1.4 times) for 5 minutes, then vacuum 600
20 at 0 Pa (0.17 times the vapor pressure of toluene)
A carrier was obtained in the same manner as in Example 2 except that the carrier was dried for a minute. The average layer thickness of the obtained carrier coating layer is 0.54 μm.
m, the coverage was 70%. The electric resistance of the carrier was 9.3 × 10 ⁸ Ωcm.

Comparative Example 5 (Production of Carrier) In Example 2, the drying condition for coating the fluorinated methacrylic resin and the styrene-MMA copolymer was set to a vacuum degree of 5 × 10 ⁴ Pa (toluene vapor pressure). (1.4 times) for 5 minutes, then vacuum degree 273
2 at 00 Pa (0.77 times the vapor pressure of toluene)
A carrier was obtained in the same manner as in Example 2 except that the carrier was dried for 5 minutes. The average layer thickness of the obtained carrier coating layer is 0.60.
In μm, the coverage was 65%. The electric resistance of the carrier was 2.8 × 10 ⁸ Ωcm.

(Evaluation) The developer was prepared by mixing the carriers of Examples 1 and 2 and Comparative Examples 1, 2, 4, 5 and the toner of Example 1 so that the toner concentration was 8%, An image quality maintenance test was conducted using a modified FX5300 machine manufactured by Fuji Xerox Co., Ltd., and the results are shown in Table 1. The first stage and the second stage
The drying pressure ratio of each stage is expressed by the ratio of the drying pressure of each stage to the saturated vapor pressure of the resin solvent. Regarding the mixing property with the additional toner, the toner charge distribution after the toner was added to the developer and mixed for 1 minute was measured, and a toner having a charge distribution of 1 peak was “excellent” and a charge distribution of 2 peaks was measured. A toner having a value of "1" was described as "poor".

As is clear from Table 1, Examples 1 and 2
The carrier had no problem in the image after copying 40,000 sheets, and the image quality maintenance was good. In addition, no scratch was found on the photoreceptor. Furthermore, high temperature and high humidity (28 ° C, 80%),
A clear image could be obtained even in an environment of low temperature and low humidity (10 ° C., 30%).

On the other hand, the carrier of Comparative Example 1 had no problem in the image after copying 40,000 sheets, had good image quality maintenance, and did not show any scratches on the photoconductor. , 8
Fog occurred under the environment of 0%). Further, when toner was added to the developer, the charge amount was not uniform even after mixing for 1 minute, and a two-peak charged toner was observed.

With respect to the carrier of Comparative Example 2, the smear on the white background began to stand out in the image after copying 5,000 sheets, so the experiment was stopped.
Further, since the electric insulation of the carrier is low, the carrier adhered from the initial stage, and black spots and white spots were generated on the image. In addition, fog occurred in an environment of high temperature and high humidity (28 ° C, 80% RH). Further, when toner was added to the developer, the charge amount was not uniform even after mixing for 1 minute, and a two-peak charged toner was observed.

The carrier of Comparative Example 4 was stopped because the stain on the white background became noticeable in the image after copying 20,000 sheets.
Further, since the electric insulation of the carrier is low, the carrier adhered from the initial stage, and black spots and white spots were generated on the image. In addition, fog occurred in an environment of high temperature and high humidity (28 ° C, 80% RH). Further, when toner was added to the developer, the charge amount was not uniform even after mixing for 1 minute, and a two-peak charged toner was observed.

With respect to the carrier of Comparative Example 5, the experiment was stopped because the stain on the white background became noticeable in the image after copying 10,000 sheets.
Further, since the electric insulation of the carrier is low, the carrier adhered from the initial stage, and black spots and white spots were generated on the image. In addition, fog occurred in an environment of high temperature and high humidity (28 ° C, 80% RH). Further, when toner was added to the developer, the charge amount was not uniform even after mixing for 1 minute, and a two-peak charged toner was observed.

[0049]

[Table 1]

[0050]

According to the present invention, by adopting the above constitution, it is possible to form a coating layer having a high film strength and a small layer thickness with a high coverage, and as a result, maintaining a high electric resistance of the carrier. As a result, the charging ability is improved, and good images can be obtained over a large number of sheets.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication location G03G 9/10 (72) Inventor Eimi Takahashi 1600 Takematsu, Minamiashigara-shi, Kanagawa Fuji Xerox Co., Ltd.

Claims (4)

[Claims] 1. Treatment with an amino group-containing silane coupling agent
For electrostatic image development with a resin coating layer on the treated core particles
In the carrier, the coverage of the coating layer is 85 to 95%.
And the average layer thickness of the coating layer is 0.01 to 0.5 μm.
10 at the rear ^3.5Electric resistance when applying a voltage of V / cm
1.5 × 10 against⁹~ 3.0 x 10 ^TenΩcm
A carrier for developing an electrostatic charge image, characterized by: 2. The electrostatic image according to claim 1, wherein the surface of the core particles treated with the amino group-containing silane coupling agent has a coating layer containing a fluorinated alkyl (meth) acrylate copolymer. Development carrier. 3. A method for producing a carrier for developing an electrostatic charge image, comprising treating a surface of a core particle with an amino group-containing silane coupling agent, applying a resin solution to the surface of the core particle, and then drying and coating the resin solution. After removing the solvent under a pressure of 0.66 to 1.6 times the saturated vapor pressure of the solvent of the resin solution at the drying temperature in the coating step, 1/1000 to 1 of the saturated vapor pressure.
The method for producing a carrier for developing an electrostatic image according to claim 1, wherein the carrier is dried under a pressure of / 20 times. 4. An electrostatic charge image developer comprising the carrier for developing an electrostatic charge image according to claim 1 or 2, and a toner using a polyester resin as a binder resin.