JPH08339096A - Electrophotographic carrier, its production, electrostatic charge image developer, image forming method and electric charge imparting member for electrophotography - Google Patents

Abstract

PURPOSE: To obtain a carrier having a high rate of rise of electrostatic charge, independent of environmental difference, capable of suppressing the reduction of the quantity of electric charges at the time of running, not causing fogging in an early stage or the contamination of the inside of a machine and capable of forming a superior image free from unevenness in density and background stain. CONSTITUTION: This carrier has a coating resin made of a copolymer consisting of 1-70wt.% acrylonitrile, 0.01-10wt.% monomer selected from among F-contg. compds. and N-contg. compds. and the balance one or more kinds of monomers selected from among styrene, alkyl acrylates and alkyl methacrylates.

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 charge image formed by an electrophotographic method, an electrostatic recording method or the like with a two-component developer, and a method for producing the same.
The present invention relates to an electrostatic image developer, an image forming method, and an electrophotographic charging member.

[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 photoconductor in the charging and exposing steps, the electrostatic latent image is developed with a developer containing toner, and the image is visualized through transfer and fixing steps. The developer used here is a two-component developer consisting of toner and carrier,
There is a one-component developer that is used alone, such as magnetic toner, but in a two-component developer, the carrier shares functions such as stirring, carrying, and charging of the developer, and the functions are separated as the developer. Currently, it is widely used because of its good controllability. In particular, a developer using a resin-coated carrier has excellent charge controllability, and it is relatively easy to improve environmental dependency and stability over time. Further, as a developing method, a cascade method or the like has been used for a long time, but at present, a magnetic brush method using a magnetic roll as a developer carrying carrier is mainly used.

In the magnetic brush method using a two-component developer,
There are problems such as a reduction in image density due to charge deterioration of the developer, occurrence of remarkable background stain, image roughness due to carrier adhesion to the image, carrier consumption, and image density unevenness. The charge deterioration of the developer is apt to occur due to the adhesion of the toner component to the carrier coat layer or the peeling of the coat. When the toner concentration is high, background stains tend to occur.

In order to prevent these charge deteriorations, the hardness of the coating resin is increased to make it difficult to peel off, or the surface energy of the coating resin is lowered to prevent the toner components from sticking to the carrier coat layer, and Efforts have been made to prevent charging deterioration by combining the methods. For example, it has been proposed to use polyacrylonitrile and an acrylonitrile copolymer for the purpose of charge stability and prevention of carrier deterioration (see JP-A-54-92244).
Since polyacrylonitrile resin is usually insoluble in an organic solvent, here, the acrylonitrile in the state of a monomer is polymerized in a state in which the core particle surface is coated, or the acrylonitrile is copolymerized with styrene and butadiene.
A method of dissolving the resin in chloroform and coating the core particles is adopted. However, it is difficult to form a uniform and stable film on the surface of the core particles by these methods. When such a carrier is used, there is a problem that the charge amount is reduced due to the impaction of the toner, or the charge amount is reduced when the toner is added, and stable image quality cannot be obtained.

[0005]

SUMMARY OF THE INVENTION Therefore, the present invention solves the above-mentioned drawbacks and provides an electrophotographic carrier having the following features and its manufacturing method, an electrophotographic developer, an image forming method, and an electronic method. An object of the present invention is to provide a photographic charging member. To prevent the destruction of carriers, the adhesion of carriers to each other, and the impaction of toner, to ensure stable high image quality and to suppress the consumption of carriers. Improve the background stain when adding toner and extend the life of the developer and charging member. It should be possible to provide image quality with excellent solid black and fine line reproducibility. Suppressing changes in chargeability due to environmental changes, etc., and improving maintainability of image quality.

[0006]

Means for Solving the Problems The inventors of the present invention have paid attention to the fact that acrylonitrile copolymer is excellent in charge maintaining property, and as a result of diligent studies, as a result, by adopting the following constitution, the above problems can be solved. succeeded in.

(1) In an electrophotographic carrier comprising a core particle coated with a resin, the resin is selected from 1 to 70% by weight of acrylonitrile, a compound containing a fluorine atom and a compound containing a nitrogen atom. The monomer component is
A carrier for electrophotography, which is a copolymer containing 01 to 10% by weight, and one or more kinds of monomer components selected from styrene, an alkyl acrylate and an alkyl methacrylate as a balance. .

(2) In the method for producing a carrier for electrophotography, in which a core particle is coated with a resin, acrylonitrile is added to
˜70% by weight, 0.01% of a monomer component selected from a compound containing a fluorine atom and a compound containing a nitrogen atom.
Wet coating of a solution of a copolymer containing 10% by weight, and one or more kinds of monomer components selected from styrene, an alkyl acrylate and an alkyl methacrylate as the balance with respect to the core particles. Then, a method for producing a carrier for electrophotography, which comprises forming a film.

(3) The electrostatic charge image developer comprising the carrier for electrophotography and the toner according to (1) above, wherein the average particle size of the toner is in the range of 5 to 10 μm. Agent.

(4) Steps of forming an electrostatic latent image on an image carrier, forming a toner image of the electrostatic latent image using a developer, and transferring the toner image to a transfer body In the image forming method, a toner image is formed using the developer described in (3) above.

(5) In a charge-imparting member for electrophotography, which comprises a substrate coated with a resin, the resin is selected from 1 to 70% by weight of acrylonitrile, a compound containing a fluorine atom and a compound containing a nitrogen atom. The monomer component is
A charge for electrophotography, which is a copolymer containing 01 to 10% by weight and one or more kinds of monomer components selected from styrene, an alkyl acrylate and an alkyl methacrylate as a balance. Granting member.

[0012]

According to the present invention, a monomer component selected from a fluorine atom-containing compound and / or a nitrogen atom-containing compound is added to a copolymer of acrylonitrile and styrene and / or (meth) acrylic acid alkyl ester. As a result, stable chargeability can be maintained even when the environment changes, toner is added, and high toner concentration is obtained. As a result, background stains are eliminated and carrier adhesion is prevented, resulting in stable high image quality. It has been possible to prolong the life of the developer and the charge imparting agent.

That is, of the copolymer components, the acrylonitrile group is excellent in charge retention, the group having a fluorine atom is excellent in impaction prevention, charge amount control and environmental stability, and the group having a nitrogen atom is a charge imparting ability. , Excellent in preventing carrier deterioration, and improving the wettability of styrene and (meth) acrylic acid alkyl ester, and by blending these copolymer components, carrier charge controllability and environmental stability are greatly improved. It has become possible to improve.

In the present invention, the content of acrylonitrile varies depending on the copolymer component to be combined, but
A range of 70% by weight, preferably 1-60% by weight, more preferably 5-60% by weight is suitable. If it exceeds 70% by weight, the difference in the amount of electrification due to the environment becomes large, and 1% by weight
If it is less than the above range, the charge control effect cannot be sufficiently exhibited.

Examples of the compound containing a fluorine atom which is one of the copolymer components according to the present invention include vinylidene fluoride, tetrafluoroethylene, hexafluoroethylene,
Monochlorotrifluoroethylene, monochloroethylene,
Fluorinated olefin monomers such as trifluoroethylene,
Examples thereof include fluorinated alkyl (meth) acrylate-based monomers such as perfluoroalkyl (meth) acrylate. These compounds contribute to reduction of surface energy, improvement of strength of coat film, and stabilization of charge amount.

The content of the fluorine atom-containing compound according to the present invention varies depending on the copolymer component to be combined,
A range of 0.01 to 10% by weight, preferably 0.05 to 10% by weight, more preferably 0.1 to 8% by weight is suitable. If it exceeds 10% by weight, the adhesion to the core particles deteriorates, and if it is less than 0.01% by weight, the charge control effect and the impaction prevention effect cannot be sufficiently exhibited.

Examples of the compound containing a nitrogen atom which is one of the copolymer components according to the present invention include nitrogen-containing acrylics such as dimethylaminoethyl methacrylate and dimethylacrylamide; 2-vinylpyridine, 4-vinylpyridine and the like. Examples thereof include vinylpyridines; nitrogen-containing aromatics such as diethylaminostyryl and paranitrostyrene; amines such as allylamine. These compounds contribute to an increase in the amount of charge, prevention of a decrease in charge when toner is added, and improvement in the strength of the coat film.

The content of the nitrogen atom-containing compound according to the present invention varies depending on the copolymer component to be combined, but is 0.
01 to 10% by weight, preferably 0.05 to 10% by weight,
The range of 0.1 to 8% by weight is more preferable.
If it exceeds 10% by weight, the fluctuation of charging due to the environment becomes large, and if it is less than 0.01% by weight, the charge control effect cannot be sufficiently exhibited.

Examples of the styrene and / or (meth) acrylic acid alkyl ester which is the copolymer component according to the present invention include styrene, methyl (meth) acrylate, and (meth).
Ethyl acrylate, isobutyl (meth) acrylate,
Preference is given to alkyl (meth) acrylates such as normal butyl (meth) acrylate.

The content of styrene and / or (meth) acrylic acid alkyl ester as the copolymer component of the present invention is 99 to 10% by weight, preferably 95 to 30% by weight, more preferably 90 to 50% by weight. A range of% is suitable. If it exceeds 99% by weight, stable charge maintainability cannot be obtained, and if it is less than 10% by weight, the charge stability tends to decrease.

The above-mentioned acrylonitrile copolymer may be used alone as the coating resin used in the present invention, but other resins should be mixed in consideration of charge control and surface property control. You can also In addition, a component that cannot be copolymerized can be used as another resin. Other resins include
Polymers of fluorine-containing monomers such as vinylidene fluoride, tetrafluoroethylene, hexafluoropropylene, monochlorotrifluoroethylene, monochloroethylene and trifluoroethylene; styrenes such as styrene, chlorostyrene and methylstyrene; methyl methacrylate, methyl acrylate, Α-Methylene aliphatic monocarboxylic acids such as propyl acrylate, lauryl acrylate, methacrylic acid, acrylic acid, butyl methacrylate, butyl acrylate, 2-ethylhexyl acrylate, and ethyl methacrylate; nitrogen-containing acrylics such as dimethylaminoethyl methacrylate; acrylonitrile and methacrylic acid. Nitriles such as ronitrile; vinyl pyridines such as 2-vinylpyridine and 4-vinylpyridine; vinyl ethers; vinyl ketones: Styrene, propylene, olefins such as butadiene; methyl silicone can be used homopolymers or copolymers such as silicone such as methyl phenyl silicone. Further, polyesters containing bisphenol, glycol and the like can also be used. When the acrylonitrile copolymer and another resin are mixed and used, the mixing ratio is 10:90 to 99 :.
1, preferably in the range of 40:60 to 99: 1.

The total amount of the coating resin is 0.1 to 10% by weight, preferably 0.3 to 7% by weight, and more preferably 0.5 to 6% by weight, based on the carrier. It is suitable for avoiding secondary characteristics, avoiding secondary obstacles, and ensuring chargeability.

The magnetic core particles used in the present invention include:
Particles having a substantially spherical shape such as ferrite particles and granulated magnetite and having a controllable surface property are suitable. The core particles having a particle size in the range of 20 to 120 μm are usually used.

The charge imparting member of the present invention can coat the surface of a metal sleeve or a blade by melting the above-mentioned coating resin and coating it by dissolving it in a solvent. A suitable thickness range for this coating is 1 to 20 μm, preferably 5 to 15 μm.

In the method for producing a carrier of the present invention, the coating resin is dissolved in a solvent and then mixed with the core particles, and the mixture is heated and stirred under reduced pressure to volatilize the solvent to coat the core resin with the coating resin. . As a manufacturing apparatus, a heating type kneader, a heating type Henschel mixer, a UM mixer, a planetary mixer, a fluidized bed, or the like can be used.

The core particles coated by the above method can be used as a carrier as they are, but further, another resin that melts at a temperature below the melting point of the coating resin according to the present invention is melt-coated or dissolved in a solvent. It is also possible to coat the other resin described above by a solution coating method and use it as a multilayer carrier.

The carrier of the present invention is mixed with a toner to prepare a toner.
Used as a component developer. The toner is obtained by dispersing a colorant in a binder resin. Examples of the binder resin used in the toner include styrenes such as styrene, parachlorostyrene, and α-methylstyrene; methyl (meth) acrylate, ethyl (meth) acrylate, n (meth) acrylate.
-Propyl, α-methylene aliphatic monocarboxylic acid esters such as lauryl (meth) acrylate and 2-ethylhexyl (meth) acrylate; Vinyl nitriles such as (meth) acrylonitrile; 2-vinylpyridine, 4-vinylpyridine Vinyl pyridines such as vinyl methyl ether, vinyl isobutyl ether and other vinyl ethers; vinyl methyl ketone, vinyl ethyl ketone, vinyl isopropenyl ketone and other vinyl ketones: ethylene, propylene,
Polymers composed of monomers such as unsaturated hydrocarbons such as isoprene and butadiene and halides thereof, halogenated unsaturated hydrocarbons such as chloroprene, or obtained by combining two or more kinds of these monomers Copolymer, further, a mixture thereof, a non-vinyl condensation resin such as a rosin-modified phenol formalin resin, an epoxy resin, a polyester resin, a polyurethane resin, a polyamide resin, a cellulose resin, a polyether resin, or these and the above And a mixture with a vinyl resin.

As the colorant used in the toner of the present invention,
Carbon black, nigrosine dye, aniline blue,
There may be mentioned chalco oil blue, chrome yellow, ultramarine blue, methylene blue, rose bengal, phthalocyanine blue or a mixture thereof.

A charge control agent, an anti-offset agent, a fluidity improver and the like can be added to the toner of the present invention.
You may add a magnetic substance fine powder as needed. As a charge control agent, a salicylic acid metal salt, a metal-containing azo compound, nigrosine, a quaternary ammonium salt, etc. can be added, and as an offset preventing agent, low molecular weight polypropylene, low molecular weight polyethylene, wax, high molecular weight alcohol, etc. are added. can do. In particular, low molecular weight polypropylene having a weight average molecular weight of 500 to 5000 is suitable.

With respect to the average particle diameter of the toner of the present invention, the smaller the diameter, the higher the image quality, and the particle diameter is 5 to 12 μm, preferably 5 to 10 μm.
The degree is good. In addition, in order to improve the liquidity,
Fluidizing agents such as silica, titania, and alumina, and cleaning aids or transfer aids such as polystyrene fine particles, polymethylmethacrylate fine particles, and polyvinylidene fluoride fine particles can be externally added. In particular, hydrophobic silica having a primary average particle size of 5 to 30 nm is preferably used.

[0031]

EXAMPLES The present invention will now be described by way of examples, which should not be construed as limiting the invention. In the examples, “part” means part by weight. [Example 1] Styrene / acrylonitrile / perfluorooctylethyl methacrylate copolymer (copolymerization ratio 7
20 parts of 0: 28: 2, Tg = 120 ° C., melt viscosity at 180 ° C. = 2.8 × 10 ³ poise) were dissolved in 100 parts of toluene. This solution and 1000 parts of Cu-Zn ferrite (manufactured by Powder Tech Co., average particle size 50 μm) were placed in a 1 L small kneader equipped with a heater and an exhaust system.
First, the mixture was mixed at room temperature for 5 minutes, then the heating medium temperature was raised to 90 ° C., and the mixture was stirred and mixed under a reduced pressure of 400 mmHg for 10 minutes, then the heating medium temperature was raised to 100 ° C., and 760 mmH
It was dried under reduced pressure of 30 g for 30 minutes. Then, the carrier of Example 1 was obtained by sieving with a 75 μm sieve.

Example 2 Styrene / acrylonitrile / dimethylaminoethyl methacrylate copolymer (copolymerization ratio 70: 28: 2, Tg = 130 ° C., melt viscosity at 180 ° C. = 2.6 × 10 ³ poise) 20 Part of toluene 10
Dissolved in 0 parts. This solution and 1000 parts of Cu-Zn ferrite (manufactured by Powder Tech Co., average particle size 50 μm) are first mixed for 5 minutes at room temperature in a 1 L small kneader equipped with a heater and an exhaust system, and then the heat transfer medium temperature. To 90 ° C., and after stirring and mixing under a reduced pressure of 400 mmHg for 10 minutes, the temperature of the heating medium is raised to 100 ° C.
It was dried under a reduced pressure of 0 mmHg for 30 minutes. And 75
The carrier of Example 2 was obtained by sieving with a μm sieve.

Example 3 Styrene / acrylonitrile / perfluorooctylethyl methacrylate / dimethylaminoethyl methacrylate copolymer (copolymerization ratio 70:
20 parts of 25: 2: 3, Tg = 128 ° C., melt viscosity at 180 ° C. = 2.8 × 10 ³ poise) were dissolved in 100 parts of toluene. This solution and 1000 parts of Cu-Zn ferrite (manufactured by Powder Tech Co., average particle size 50 μm) were placed in a 1 L small kneader equipped with a heater and an exhaust system.
First, the mixture was mixed at room temperature for 5 minutes, then the heating medium temperature was raised to 90 ° C., and the mixture was stirred and mixed under a reduced pressure of 400 mmHg for 10 minutes, then the heating medium temperature was raised to 100 ° C., and 760 mmH
It was dried under reduced pressure of 30 g for 30 minutes. Then, the carrier of Example 3 was obtained by sieving with a 75 μm sieve.

[Comparative Example 1] 1000 parts of Cu-Zn ferrite (manufactured by Powdertec Co., average particle size: 50 µm), 150 parts of trichloroethylene, acrylonitrile monomer 1
00 parts and 0.05 parts of potassium persulfate were placed in a stainless rotary dry mill pot, stirred until uniform, and then polymerized. Then, the solvent was suction-dried and further dried in a thermostat at 105 ° C. to obtain a carrier of Comparative Example 1.

Comparative Example 2 Styrene / acrylonitrile copolymer (copolymerization ratio 70:30, Tg = 115 ° C., 1
20 parts of melt viscosity at 80 ° C. = 2 × 10 ³ poise) was dissolved in 100 parts of toluene. This solution and Cu-Zn ferrite (manufactured by Powder Tech Co., average particle size 50 μm) 10
In a 1L small kneader equipped with a heating heater and an exhaust system, 00 parts was mixed for 5 minutes at room temperature, then the temperature of the heating medium was raised to 90 ° C., and the pressure was reduced to 1 mm under a reduced pressure of 400 mmHg.
After stirring and mixing for 0 minutes, the temperature of the heating medium was raised to 100 ° C., and drying was performed for 30 minutes under a reduced pressure of 760 mmHg. Then, the carrier of Comparative Example 2 was obtained by sieving with a 75 μm sieve.

(Production Example 1 of toner) Binder resin (styrene-n-butyl methacrylate, copolymerization ratio 70:30) 87 parts Carbon black (BPL manufactured by Cabot Co.) 8 parts Charge control agent (TRH manufactured by Hodogaya Chemical Co., Ltd.) 1 part Polypropylene wax (660P manufactured by Sanyo Kasei Co., Ltd.) 4 parts Toner particles having an average particle size of 7.5 μm were obtained by a kneading and pulverizing method using the above materials. Then, 100 parts of the toner particles and 1 part of colloidal silica (R972 manufactured by Nippon Aerosil Co., Ltd.) were mixed with a Henschel mixer to obtain a toner for evaluation.

(Evaluation) The carriers obtained in Examples 1 to 3 and Comparative Examples 1 and 2 were mixed with the toner obtained in Toner Production Example 1 so as to have a toner concentration of 5% to prepare an evaluation developer.
About these developers, Fuji Xerox Viva
Performed an image quality evaluation test using a modified ce550 machine, and
The coated state of the carrier was observed with an electron microscope and the results shown in Table 1 were obtained. As is clear from Table 1, the carriers of Examples 1 to 3 had better coat states than those of Comparative Examples 1 and 2, were excellent in charging stability, were not affected by environmental changes, and had a background portion. It has been found that a clean image quality can be provided.

[0038]

[Table 1]

Example 4 Styrene / acrylonitrile / perfluorooctylethyl methacrylate / dimethylaminoethyl methacrylate copolymer (copolymerization ratio 70:
20 parts of 25: 2: 3, Tg = 128 ° C., melt viscosity at 180 ° C. = 2.8 × 10 ³ poise) were dissolved in 100 parts of toluene. A developing roll sleeve (made of stainless steel) for a laser printer 4105 manufactured by Fuji Xerox Co., Ltd. was dipped in this solution to form a coat layer having a thickness of 10 μm on the sleeve surface.

Comparative Example 3 A developing roll sleeve (made of stainless steel) for a laser printer 4105 manufactured by Fuji Xerox Co., Ltd. was used as it was.

(Production Example 2 of toner) Binder resin (styrene-n-butyl methacrylate, copolymerization ratio 70:30) 44 parts Magnetite powder (EPT-1000 manufactured by Toda Kogyo KK) 50 parts Charge control agent (Hodogaya Chemical Co., Ltd.) TRH) 2 parts polypropylene wax (660P manufactured by Sanyo Kasei Co., Ltd.) 4 parts Toner particles having an average particle size of 9.0 μm were obtained by a kneading and pulverizing method using the above materials. Then, 100 parts of the toner particles and colloidal silica (R972 manufactured by Nippon Aerosil Co., Ltd.)
Toner for evaluation was obtained by mixing 8 parts by a Henschel mixer.

(Evaluation) The sleeves obtained in Example 4 and Comparative Example 3 were mounted on a laser printer 4105 manufactured by Fuji Xerox Co., Ltd., and an image quality evaluation test was conducted using the toner of Toner Production Example 2. The results are shown in Table 2. It was As is clear from Table 2, the sleeve of Example 4 has better solid density and background stain than Comparative Example 3, and is superior in image quality stability.

[0043]

[Table 2]

[0044]

EFFECTS OF THE INVENTION By adopting the above-mentioned constitution, the present invention has a high charging rate and is not affected by environmental differences.
And since there is no decrease in the amount of charge during running,
It has become possible to provide excellent image quality without uneven density of images and background stains without causing fogging at an early stage or causing in-machine contamination. In addition, the maintainability of the developer can be dramatically improved.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masaaki Usami 1600 Takematsu, Minamiashigara City, Kanagawa Prefecture, Fuji Xerox Co., Ltd. (72) Inventor Haruhide Ishida 1600 Takematsu, Minami Ashigara City, Kanagawa Prefecture, Fuji Xerox Co., Ltd.

Claims (5)

[Claims] 1. A carrier for electrophotography comprising a core particle coated with a resin, wherein the resin is selected from 1 to 70% by weight of acrylonitrile, a compound containing a fluorine atom and a compound containing a nitrogen atom. 0.0 monomer component
A carrier for electrophotography, which is a copolymer containing 1 to 10% by weight and one or more kinds of monomer components selected from styrene, alkyl acrylates and alkyl methacrylates as a residual amount. . 2. A method for producing an electrophotographic carrier in which a core particle is coated with a resin, wherein 1 to 1 of acrylonitrile is used.
70% by weight, 0.01 to 0.01% of a monomer component selected from a compound containing a fluorine atom and a compound containing a nitrogen atom.
A solution of a copolymer containing 10% by weight and a residual amount of one or more monomer components selected from styrene, an alkyl acrylate and an alkyl methacrylate is wet-coated on the core particles. A method for producing an electrophotographic carrier, which comprises forming a film. 3. An electrostatic charge image developer comprising the electrophotographic carrier according to claim 1 and a toner, wherein the toner has an average particle size in the range of 5 to 10 μm. 4. A step of forming an electrostatic latent image on an image carrier,
Forming a toner image from the electrostatic latent image using a developer,
An image forming method having a step of transferring the toner image onto a transfer body, wherein the developer image according to claim 3 is used to form a toner image. 5. A charge imparting member for electrophotography, comprising a substrate coated with a resin, wherein the resin is selected from 1 to 70% by weight of acrylonitrile, a compound containing a fluorine atom and a compound containing a nitrogen atom. 0.0 monomer component
A charge for electrophotography, which is a copolymer containing 1 to 10% by weight and one or more kinds of monomer components selected from styrene, alkyl acrylates and alkyl methacrylates as a residual amount. Granting member.