JPS59131942A - Electrophotographic developer - Google Patents

Abstract

PURPOSE:To obtain an electrostatic developing ferrite carrier having desired electric resistance and long life by forming a tin oxide film on the surface of a garnet type ferrite, and a film of a fluorinated resin or an epoxy resin having a specified thickness on the surface of the ferrite carrier having a specified particle diameter. CONSTITUTION:Each surface of 10-1,000mum diameter particles of a hexagonal ferrite carrier is coated with a soln. prepd. by dissolving a fluororesin or an epoxy resin in a solvent in a fluidized bed to form a film. Since said resin film adheres fast to the surface of the carrier and inhibits adhesion of a toner to its surface during development, the carrier is extended in life when it is used as a binary carrier for an electrophotographic machine. When the resin coating film is <=10nm thick, the carrier is shortened in life by the thinness of the film, and when the film exceeds 1,000mum thickness, although resistance and chargeability characteristics of the developer can be optionally changed, magnetic characteristics decreases, image characteristics are adversely affected, and a sharp image cannot be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dry type developer used for developing electrophotography and the like.

The two-component electrostatic developer that is commonly used consists of a magnetic carrier and a resin as its main components. , the latent image is fixed and an image is obtained. However, when the magnetic main 1/rear is used repeatedly due to this latent image and fixation, frictional heat is generated inside the developing machine, and the toner melts with the temperature and is transferred to the surface of the magnetic kyrelia. If the magnetic carrier adheres, the friction zone ■1 and electrical resistance of the magnetic carrier will change significantly (because of image blurring or printing).
There is a disadvantage that a reduction of 1 degree occurs and the image quality deteriorates significantly. This blurring of images and decrease in print density are directly related to the lifespan of the magnetic chitria, so in order to avoid extending the lifespan of the magnetic carrier, contamination due to toner adhesion to the magnetic main 1/rear, In other words, in order to prevent 1-nurse pent, the surface of the magnetic key 17 rear is coated with resin.
- It is necessary to prevent reactions with magnetic carriers.

The present invention has been made to alleviate the above-mentioned drawbacks,
The main purpose of the present invention is to form a tin oxide film on the surface of garnet-type ferrite, and then use a fluorine-based resin or TpoA-oxy resin, which has high resistance and high moisture resistance, to form a tin oxide film on the surface of garnet-type ferrite.
~i, oooμm) ■ Thickness 0 on the surface of the light carrier
．． The object of the present invention is to produce a film of 01-3071m to obtain a long-life ferrite carrier for electrostatic development such as electrophotography, which has a desired electrical resistance.

The film-forming resin of the present invention is made by using a fluorine-based resin alone or by fixing a thin film N9 on a magnetic film or two with the fluorine-based resin, and then forming a rough double film with an epoxy resin. It is possible to maintain the mutual effect of triboelectrification control and long life by adjusting the electrical properties of the magnetic (/1 = l: 1-rear) as desired.The resin film of the present invention has a hexagonal system. Forms a strong film on the surface of the ferrite [Main 1 aria], and reduces the possibility of peeling off of the film from the magnetic Gitria during development, which was a drawback in the past, and the contamination caused by toner adhering to the soil of the resin film. Because of the magnetic properties of chitoria, it has good advantages.

Next, the effects of the present invention will be explained with reference to Examples.

Example 1 A solution obtained by melting a fluorine-based resin in a commonly used solvent was poured onto the surface of a hexagonal ferrite crystal. Form a film by fusion using the JJ layer (7.
[Has a strong film]] - Lie [・4: (・Rea was obtained. Evoxy toner (for Xerox 3500) was added to the Feli 1 carrier on which this film was formed so that the toner concentration was 3% by weight. As a result of image ast using the current Ffi agent of +l +T, which was mixed to create a developer for image evaluation by fv, it was possible to copy more than 100,000 sheets of images, and compared to the conventional iron powder -1 tria. Approximately 3
It was found that the lifespan of Fephyt-*-Il was twice as long.

Example 2 The same strip as in Example 1 (after forming the fluorine-based resin film in step 4, a high-resistance double film was formed on the rough surface with epoxy resin, and the same strip as in Example 1 was prepared. As a result of making a developer and making 7 images, it was possible to make more than 100,000 copies at a distance of 1 m.As a result of 1-1, the magnetic material has a long life approximately three times longer than that of conventional iron powder carriers. It was confirmed that there was a carrier.

In addition, the resin according to the present invention]-Fing has a film thickness of
If the film is less than 0.01 μm, the life of the film will be short due to the thinness of the film.
Although it is possible to arbitrarily change the electrical resistance and charging characteristics of the developer, the disadvantage is that the magnetic characteristics decrease, which adversely affects the image characteristics and makes it impossible to obtain a clear image. There is. Because of i3-, the thickness of the film on the chitria surface is 0.01-i,
A range of 0.00μm is appropriate, but the optimum range for the film is 0.0μm. ll1m-1,000μm is desirable. Further, the starting material for producing the resin film may be either a polymer on a polymer or a polymer.

As described above, the resin film according to the present invention firmly adheres to the surface of the main 11 rear, and toner does not easily stick to the surface of the film during development, so it is suitable for use with two-component carriers for electronic copying machines. When used as an electrophotographic developer, its industrial value is extremely low due to its long life. Relationship with the case of the person who filed the patent application Address of the patent applicant: 2-1-2 Marunouchi, Chiyoda-ku, Tokyo Name (5
08) Hitachi Metals Co., Ltd. Telephone: Tokyo 03-284-4642 "Claims" and "Detailed Description of the Invention" columns of the specification.

Contents of correction As per attached sheet.

1. Correct the statement in the Claims column as follows 3 in Clear1m.

[)] After forming a conductive film of tin oxide (11) on the surface of the light, a strong high resistance, high durability 1tjlt'4 fluororesin or epoxy resin is used to form a particle size of 10 to 1,000.

μm garnet-based 7-element [・0 on the surface of the carrier]
．． An electrophotographic developer characterized by forming a film having a thickness of 01 to 30 μm. 2. Description [The description in column 1 of the detailed description of the invention is corrected as follows.

(1) On page 3, line 15 of the specification, "1 for hexagonal system is corrected to 1 for garnet system.

that's all °−1°− 525-

Claims (1)

[Claims] After forming a conductive tin oxide film on the surface of Feray I-, it is coated with a strong, high-resistance, high-moisture-resistant fluororesin or eboxy resin. An electrophotographic developer characterized by forming a film with a thickness of 0.01 to 30 μm on the surface of a fly gear.