JPS6015062B2 - Resin-coated carrier for electrophotographic dry toner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a resin-coated carrier for use in negatively charged electrophotographic dry toner.

Generally, carriers for electrophotographic dry toners include magnetic materials such as iron powder, oxidized iron powder, and glass beads.

On the other hand, toners mixed with these carriers may be negatively charged, such as phenol resin, polystyrene resin, acrylic ester, methacrylic ester, styrene-acrylic ester copolymer, polyester, ester gum resin, gilsonite, Epoxy resins, maleic acid resins, xylene resins, styrene-butadiene copolymers, etc. are used. However, when a magnetic material such as iron powder is used as the carrier, its low electrical resistance causes the charge of the electrostatic latent image formed on the electrophotographic photoreceptor to leak.
It is not possible to form a clear image.

Therefore, in order to maintain high resistance of this type of carrier, it has been proposed to coat the surface of the carrier particles with an appropriate insulating resin. Known resins used here include polyvinyl chloride, polyvinylidene chloride, acrylic ester (or methacrylic ester) and styrene copolymers. However, since the film strength of all these resins is weak, the film peels off or wears out during mixing of the carrier and toner or during development, reducing the insulation properties of the carrier, resulting in stable and strong negative chargeability. This method not only makes it impossible to obtain toner, but also causes electrostatic aggregation of carriers.

The present invention is a resin coated carrier that eliminates the above drawbacks,
Due to the high film strength of the resin coating the carrier, there is no peeling or abrasion of the film even during mixing of the carrier and toner or during development, and therefore it is possible to give a stable negative charge to the toner for electrophotographic drying. This is a resin-coated carrier for toner. Such a resin-coated carrier has a core material surface coated with a material whose main component is poly-y-alkyl-L-glutamate.

Poly-y-alkyl-L-glutamate used in the present invention is a resin having repeating units of y-alkyl-L-glutamate, which is a type of amino acid, and among poly-y-alkyl-L-glutamates, poly-y-methyl The film formed by drying a solution of -L-glutamate dissolved in a suitable solvent is strong and has excellent abrasion resistance, so it is optimal as the coating resin material of the present invention.

For polyy-alkyl-L-glutamate, commercially available products are Azikoat A-2000 and Azikoat XB-9000.
, Azikoat XB-400, Azikoat TC-10, Azikoat S-30 (manufactured by Ajinomoto Co., Inc.), and the like. In the present invention, the coating resin material may be polyy-alkyl-L-glutamate alone, but depending on the type of core material, it may be used to improve the adhesion to the core material, to improve the abrasion resistance, or to improve the toner's Poly-alkyl-L-glutamate may be blended with other resins in appropriate amounts for the purpose of preventing adhesion, controlling the toner charge amount, imparting fluidity to the developer, and the like.

Examples of such resins include epoxy resins, vinyl chloride-vinyl acetate copolymers, urethane resins, and polyester resins. As the core material, in addition to magnetic materials such as iron powder, oxidized iron powder, ferrite, and nickel, glass beads, silica particles, sodium chloride, ammonium chloride, and Rochelle salt can be used.

The flow diameter of the core material is 50 to 1000 mm, preferably 50 to 1,000 mm.
It is about 300 Buddha skins. To illustrate the method for manufacturing the resin-coated carrier of the present invention, core material particles are suspended in an atmosphere of about 30 to 50 q0, and a dilute solution of a coating material containing polyy-alkyl-L-glutamate as a main component is spray-dried using a spray dryer. Alternatively, there is a method in which core material particles are suspended in the dilute solution, and then the core material particles are spray-dried in an atmosphere at the temperature described above.

A dilute solution of polyy-alkyl-L-glutamate is
It is formed by adjusting poly y-alkyl-L-glutamate to an appropriate viscosity using ethylene dichloride, tetrachloroethylene, dimethylformamide, trichloroethylene, methanol, toluene, methyl ethyl ketone, ethyl acetate, etc. as a main solvent or dilute solvent. The coating resin layer formed on the surface of the core material may have a thickness of approximately 0.1 to 2 degrees.
Incidentally, organic pigments, organic dyes, plasticizers, etc. used in the secondary developing powder can be added to the coating resin layer of the present invention. The resin-coated carrier IJ of the present invention can be applied to all conventional negatively charged toners, and can be made into a strong and stable negative polarity toner.

Example 1 Iron powder with a particle size of 200 mm was suspended in an atmosphere of 3 mm, sprayed with Azikoat A-2000 (2.5% tetrachlorethylene solution) and dried to form a resin with a film of approximately 1 mm. A coated carrier was created.

9 parts by weight of this resin-coated carrier and 1 part by weight of toner for an electronic copying machine PPC-900 manufactured by Toriko Co., Ltd. were mixed together to prepare a developer. The toner charge amount of this developer was measured by a blow-off method and was found to be about 130 c/night. When the above-mentioned developer was used for cascade development of an Se plate having a static latent image, a good positive image without background stains was obtained. Example 2 Instead of Azikoat A-2000 (2.5% tetrachlorethylene solution), 50 parts by weight of Azikoat A-2000 was mixed with 5 parts by weight of Pantex 510$ (urethane resin from Dainippon Ink Co., Ltd.) Solution of resin (2.5%
Example 1 except that tetrachlorethylene solution) was used.
A developer was prepared in the same manner as above, and cascade development was performed.

Claims (1)

[Claims] 1. A resin-coated carrier for an electrophotographic dry toner, in which the surface of core substance particles is coated with a material containing poly-γ-alkyl-L-glutamate as a main component.