JPS59166968A - Coated carrier - Google Patents

Abstract

PURPOSE:To obtain a coated carrier having excellent quality by covering a carrier for electrophotography with a resin contg. pulverous powder of conductive zinc oxide. CONSTITUTION:200g A 10% toluene soln. prepd. by mixing 100g silicone varnish and 5g conductive zinc white (ZnO) with respect to 1kg sponge-like iron powder having 40mu average grain size is sprayed on the surface of the iron powder in a Brewster type circulating fluidized bed under the condition of 85-90 deg.C, then the coating is cured for 20min in a furnace kept at 200 deg.C and after cooling, the iron powder is passed through a 150-mesh sieve, by which the flocs are removed and the resin coated carrier having low surface energy is obtd. A beautiful image having no edge effect is obtd. by such carrier.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a coated carrier for an electrophotographic developer, and more particularly to a coated carrier in which the carrier is coated with a resin containing ZnO.

Conventionally, as an electrophotographic method, US Pat. No. 2,297,691
No., Special Publication No. 42-23910, Special Publication No. 45-2474
These methods are described in Publication No. 8, but these methods uniformly charge the photoconductive layer and perform original image exposure C according to the original to eliminate the charge outside the optical image area and form a latent image. The image is developed with toner powder, transferred to paper or cloth as necessary, and permanently fixed by heating and pressure.

Methods for developing R images include magnetic brush, cascade,
It can be visualized using various developing methods such as fur brush touchdown and powder cloud.

In the magnetic brush development method used in the present invention, a mixture of carrier iron powder and toner is used as a developer. Continuous copying of a large number of sheets of this developer causes the toner to fuse to the surface of the carrier. Another is that during continuous copying, the carrier surface becomes covered with fine toner accumulation.

Such deterioration usually occurs after 1000 to 20,000 sheets are printed, making it unsuitable for high-speed copying machines.

Therefore, a carrier coated with a resin has been proposed to improve the above-mentioned drawbacks.

These are intended to solve the aforementioned deterioration, but many of the resins used for coating have high electrical resistance, so when used as a developer, they may cause edge phenomena, reduced image density, or no images. I like it...

In order to prevent such a phenomenon, the electrical resistance must be adjusted. Carbon black is a conventionally used material, but carbon black dispersed in grease has poor wettability and poor durability.

Furthermore, even if the carbon is uniformly dispersed, the desired effect can be obtained in a localized area where the carbon is present, but when viewed as a whole, it is not preferable because there will be areas with high and low resistance.

The purpose of the present invention is to provide a coated carrier for electrophotographic development which improves the above-mentioned drawbacks, and its objects are as follows.

(1) Lower the resistance of the coating resin (2) Extend the life of the developer (6) Make the toner remaining after transfer available for reuse (reduce running costs to T8) (4) Under various environments In other words, the present invention is characterized by the fact that the image is clear.
The coating carrier is coated with a coating resin containing O).

The conductive zinc white (ZnO) used in the present invention has a particle size of 10
μm! -1, the electrical resistivity is preferably 100Ω·cm or less.

It has already been mentioned that carriers coated with resin only have a strong "Paedzage" phenomenon, and the image quality is poor in the % range, so the electrical resistance must be adjusted. The fine powder of ) has the following effects as a coated carrier resistance adjuster.

1. Extremely good dispersibility in resin binders.

2. Does not inhibit adhesive strength to iron powder carrier.

This conductive zinc oxide fine powder ('Zn0) is coated with resin 100%.
0.1 to 10 parts by weight, preferably 0.6 to 7 parts by weight.

A large number of coating resins are used in the present invention, including known materials, but representative ones include fluororesins, various fluorinated polymers, melanin resins, xylene epoxy resins, and polyphenylene resins. Oxide resin, silicone resin, polyester resin, polyamide resin, styrene-vinyl chloride copolymer resin, styrene-methyl methacrylate copolymer resin, styrene-butyl methacrylate copolymer resin, styrene-bucdiene copolymer resin, etc. used.

The method for producing the coated carrier in the present invention is to mix the resin to be coated and the above-mentioned conductive zinc white powder in a solvent (toluene).

xylene, MEK), etc., mix a carrier with this dispersion, coat it on the carrier by a spray dryer method, fluidized bed method, etc., dry it, granulate it, sieve it, and use the passed-through as a coated carrier. use

Specific examples of effects will be shown below according to Examples.

[Example 1] Spongy iron powder with an average particle size of 40μ (EFV manufactured by Nippon Iron Powder Co., Ltd.)
For 1 kg, 200 g of a 10% toluene solution containing 100 g of silicone resin (SR-2406 manufactured by Toshi Silicone Co., Ltd.) and 5 g of conductive zinc white (particle size 5 μm, resistivity 100 Ω・am) was heated at 85 to 90°C. Under the conditions of Wu
The surface of the iron powder was sprayed in a circulating fluidized bed, and then heated in a furnace at 200°C for 20 minutes.
It was cured for minutes, removed from the oven, cooled, and passed through a 150 mesh sieve to remove agglomerates, yielding a low surface energy resin coated carrier.

This carrier and NP8500 super toner 8wt
When an image was printed using NP8500 super material using 1JJ ml of φ mixed, the resulting image was a beautiful image with no etch effect, and no toner adhesion to the background was observed. [Example 2] Epoxy-modified Teflon enamel Teflon S 954 101 (Du Pont
As a result of carrying out a double-extraction experiment in the same manner as in Example 1 except that a 150 g product manufactured by Co., Ltd. was used, a beautiful copy image was obtained in which the black solid areas were uniformly developed and there was no edge effect.

Applicant: Canon Co., Ltd.

Claims (1)

[Claims] Coated carrier for electrophotography in which the carrier is coated with a resin containing conductive zinc oxide fine powder (ZnO) -)