JPS59127057A - Electrophotographic developing agent - Google Patents

Abstract

PURPOSE:To extend a life of a ferrite carrier for electrostatic development by forming a film of conductive tin oxide on the surface of the ferrite and then a film of a specified thickness made of a fluororesin or epoxy resin high in electrical resistance and humidity resistance on the surface of a hexagonal ferrite carrier having a specified particle diameter. CONSTITUTION:An electrostatic developing ferrite carrier is obtained by forming a tin oxide film on the surface of a hexagonal ferrite and then a 0.01-30mum thick film made of a fluororesin or epoxy resin having high electrical resistance and humidity resistance on the surface of a ferrite carrier of 10-1,000mum particle diameter. Triboelectrification of the magnetic carrier can be controlled by forming a single layer of the fluororesin alone or double layer films of the thin fluororesin stuck first and further the epoxy resin to optionally change electrical properties. Said film forms a tough film on the surface of the hexagonal ferrite carrier and stripping of the film from the carrier during development and subsequent staining due to adhesion of the toner to the resin occur scarcely, and therefore, the obtained magnetic carrier is extended in life.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a ferrite carrier for a dry developer used in phenomena such as electrophotography.

The commonly used two-component electrostatic developer is a mixture of magnetic Kyrelia and resin-based toner, which is triboelectrically charged and transported by the magnetic Kyrelia when the toner comes into contact with the photosensitive paper. Then, the latent image is determined and an image is obtained. However, when magnetic carriers are used for a long time due to repeated latent image and fixing, frictional heat is generated inside the developing machine, causing temperature drop.

As the toner rises, the toner melts and adheres to the surface of the magnetic carrier, and the frictional charging and electrical resistance of the magnetic carrier change significantly, causing image blurring and a decrease in print density, resulting in a significant drop in image quality. There are drawbacks to doing so. This image blurring and decrease in printing density are directly related to the lifespan of the magnetic carrier, so in order to extend the lifespan of the magnetic carrier, it is necessary to prevent contamination caused by fusion of the t-ner to the magnetic carrier, i.e., 1-ner pen. In order to prevent this, it is necessary to coat the surface of the magnetic key I/Sj' with a resin to prevent the reaction between 1 to 2 and the magnetic chitria.

The present invention has been made to improve the above-mentioned drawbacks, and the main purpose of the present invention is to form a tin oxide film on the surface of the hexagonal ferrite 1 and then coat it with high resistance and high kJM properties. Using fluorine resin or epoxy resin, particle size is 10~
The purpose of this invention is to produce a film with a thickness of 0.01 to 30 μm on the surface of ferrite chitria with a thickness of 0.0 μm to obtain a ferrite carrier for electrostatic development such as electrophotography, which has a desired electrical resistance and has a long life.

The film-forming resin of the present invention is made by using a fluorine-based resin alone or by fixing a thin film on a magnetic carrier with the fluorine-based resin, and then forming a double film with an Evo-Δxy-based resin. By arbitrarily changing the electrical properties, the phase opening effect of C thickness gap 1) control of electrical current and longer life can be realized.

It is possible to hold it. The resin film of the present invention forms a strong film on the surface of hexagonal ferrite and chitria, and the film does not peel off from magnetic carriers during development, which was previously thought to be a drawback, and toner does not adhere to the soil of the resin film. 11 It has the advantage that it is less likely to be contaminated by adhesion, and therefore has a long lifespan.

Next, the effects of the present invention will be explained using examples.

Example 1 A solution obtained by melting a fluorine-based resin in a commonly used solvent was subjected to hexagonal ferrite chitria formation,
Obtained Huerai L. Kitria with a strong film/j
A developer for image evaluation was prepared by mixing eboxy-based [-ner (for Xerox 3500)] to the ferrite chytria thus formed into a film so that the I-ner was adjusted to 3% by weight. As a result of image assembling using this developer, more than 100,000 image copies can be made, and compared to conventional iron powder carriers, the life expectancy is approximately 3 times longer. One thing was recognized.

Example 2 After forming a film of fluorine-based resin under the same conditions as in Example 1, a high-resistance double film is formed on the surface using epoxy resin, and a developer is prepared under the same conditions as in Example 1. As a result of stoshi,
Similarly, more than 100,000 copies could be made.

As a result of the above, the conventional iron powder ki A? It has been confirmed that there is a magnetic gear 17 rear with a lifespan approximately three times longer than that of the rear.

In addition, the resin coating according to the present invention has a film thickness of
If the thickness is less than 0.01 μm, the film will be thin and the lifespan of the developer will be short. On the other hand, if the film thickness exceeds i,00 μm or more, the electrical resistance and charging characteristics of the developer cannot be changed arbitrarily. Although this is possible, it has the drawback that the magnetic properties are reduced, which adversely affects the image properties and makes it impossible to obtain clear images. Therefore, the appropriate thickness of the film on the carrier surface is in the range of 0.01 to 1,000 μm, but the optimal film range is preferably 0.1 μm to 1,000 μm. The starting material for this can be either a polymer or a polymer.

As described above, the resin film according to the present invention firmly adheres to the surface of the 17 rear, and toner does not easily stick to the surface of the film during development, so it can be used as a two-component carrier for electronic copying machines. If it is, its industrial utility value is extremely large due to its long life.

Claims (1)

[Claims] After forming a conductive tin oxide skin F3 on the surface of the ferrite, the surface of a hexagonal ferrite carrier with a particle size of 10 to 1,000 μm is coated with a strong, high-resistance, high-moisture-resistant fluororesin or eboxy resin. An electrophotographic developer characterized in that it forms a skin lI9 with a thickness of 01 to 30 μm.