JPS58159548A - Carrier for electrophotographic developer - Google Patents

Abstract

PURPOSE:To obtain a titled carrier which has always a stable frictional electrifying property and is highly durable by coating carrier cores with poly(phenylene oxide/phenylene sulfide/sulfone). CONSTITUTION:The coating material consisting of the poly(phenylene oxide/ phenylene sulfide/sulfone) expressed by the formula is obtained by condensation polymn. of 4-mercaptophenol and 4,4'-dichlorodiphenyl sulfone in a solvent mixture of chlorobenzene and sulfolane. The coating material is dispersed in an aq. medium and the liquid is sprayed on the surface of carrier cores having 10- 1,000mu particle sizes, and is then dried, whereby the continuous film of 0.1-20mu thickness having no pinholes is formed. The coating material have high tensile strength and heat resistance and exhibits high adhesive strength to carrier cores; therefore the material is highly durable aginast mechanical impact and retains the initial characteristics of the developer without dislodging and stripping of the coating resin from the core surfaces upon long-term use.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a carrier for an electrophotographic developer, and more particularly to an improvement in the coating material of the carrier.

In electrophotography, a two-component developer consisting of a toner and a carrier has conventionally been used. Various carriers are known, such as sodium chloride, aluminum chloride, sodium nitrate, potassium chlorate, granular silicone, methyl methacrylate, glass,
Silicon dioxide, iron, steel, fly I, nickel, cobalt, and mixtures thereof are known.

However, if this carrier is used for a long time, particles will collide with each other or the particles will collide with the wall of the developing section of the copier!
The so-called i-ner filming phenomenon occurs, in which the toner fuses to the carrier surface due to i-bumping, etc., which deteriorates the charging characteristics of the developer, and eventually makes it impossible to charge the toner to an appropriate amount.1! Ru.

In order to reduce such toner filming and extend its service life, a method has been proposed in which the surface of the carrier is coated with a non-adhesive resin to the 1-toner resin. For example, carriers using low surface energy resins similar to Kylia (Japanese Unexamined Patent Publication No. 48-90238@) coated with low surface energy saturated fluorocarbon resins are known. However, conventional carrier coating resins do not have sufficient tensile strength or compressive strength and are prone to wear and breakage. Furthermore, the adhesion to the carrier core is not sufficient. Therefore, during long-term use, collisions between particles and collisions with the copying machine cause the coating material to come off from the carrier surface in the form of chips, flakes, or the entire layer.
This will cause deterioration of the properties of the developer, resulting in defective copies and deterioration of copy image quality. Therefore, it is necessary to replace it frequently, which is time-consuming and expensive.

Furthermore, in order to increase the adhesion of the coating resin to the carrier core, attempts have been made to avoid frequent treatments prior to coating the resin, but this has not yet yielded satisfactory results (currently, no results have been obtained). It is.

It is an object of the present invention to overcome the drawbacks of the prior art, in particular by coating the carrier core with a high tensile and compressive strength coating having strong adhesion to the core. It is an object of the present invention to provide Kyrelia which has excellent durability and always has stable triboelectric charging properties without causing deterioration of the characteristics of the developer due to chipping, flaking, etc. even when used for a long time.

That is, the present invention is a carrier for an electrophotographic developer characterized by being coated with poly(phenylene oxa 11 fluorophide/sulfone) having the following general formula.

General formula To describe the present invention in detail, all of the following conventionally known key and rear cores are used as the carrier core, and representative examples thereof include sodium chloride, aluminum chloride, aluminum chloride, and nitric acid. Sodium, potassium chlorine M salt, granular silicone, methyl methacrylate, glass, silicon dioxide, iron, steel, ferrite, nickel, cobal] and mixtures thereof, as well as cores thereof coated with resin, etc. carrier 1
The particle size of (a) is preferably about 10 to 1000 μm in diameter.

The poly(noenylene Δoxide/phenylene sulfide/+J ruphon) represented by the general formula used in the present invention can be obtained, for example, by the following reaction formula.

According to the reaction formula, 4-mercapmylphenol and
A copolymer is obtained by condensation polymerization of 4.4=-diq[]rodiphenyl sulfone in a mixed solvent of chlorobenpine and sulfolane. Poly(phenylene oxide/phenylene nalphide/sulfone) has higher tensile strength and heat resistance than other coating resins, and is also extremely compatible with inorganic materials (high adhesion to carrier cores). Therefore, it has a high degree of durability against mechanical shocks such as collisions between developer particles and collisions between particles and the developing device or photoreceptor, and the coating resin will not chip even after long-term use. It is possible to always provide a stable copy image without damaging the properties of the developer due to DI2 Ill or scraping from the core surface due to flaking or the like.

The film thickness of the poly(phenylene 1)-rulphide/sulfone resin on the surface of the carrier core can be adjusted to any appropriate thickness depending on the application, but it is preferable that the surface of the carrier core be coated uniformly and continuously without pinholes. It is preferable that the thickness is sufficient to form an N film. Specifically, about 0.1~
The thickness is about 20μ, more preferably 0.3 to 8μ, and optimal durability, triboelectric charging properties, toner pressure adhesion resistance, and copy image quality can be obtained at this time.

The coating material of the present invention can be applied to a carrier either directly onto the carrier surface or as an overcoating for a carrier coated with a conventional coating material;
It may also be used as a primer coating prior to coating the conventional coating material. The hair/rear of the present invention 6 thus obtained is highly abrasion resistant, has strong resistance to mechanical impact during use, and is extremely durable.

The toner used with the carrier of the present invention may be any conventionally known material, such as coumaron-indene resin, phenol formaldehyde resin, rosin-modified phenol formaldehyde resin, methacrylic acid resin, polystyrene resin 1, polyethylene resin, etc. A toner composed of a resin component and a colorant such as carbon black is appropriately used.

:1 The ratio of carrier to tree may be used as usual. For example, in cascade and magnetic brush development systems, a typical ratio of 1 to 100% carrier is 100% carrier per 1 part by weight of toner.
~400 Juebu area.

The present invention will be explained in detail below.

Example 1 400 meshes or less of poly(phenylene oxide/phenylene salura fluid/salvon) was dispersed in 300 mA of water, and the solution was mixed at a rate of 10 m°C per 100 g of steel beads with an average particle size of 50 to 150 μm at a temperature of 85 to 90 μm. °C condition F
spray onto the surface of the steel beads in a circulating fluidization bed of the Wurster (WIJrStQr) type, and then
The poly(phenylene oxide/ 1q of phenylene sulfide/sulfone coated gear rear.

99 parts by weight of the Ki-11 rear of the present invention obtained in the following manner,
Toner EFT6200 (
(manufactured by Ricoh Co., Ltd.) and 1 part by weight in a ball mill for 1 hour.
As a result, a toner charge amount of 10 μC/a was obtained. Furthermore, this developer was heated to a diameter of about 10 CIIl and a surface speed of about 10 m.
The mixture was stirred using a deterioration tester at a speed of 1/2 min. After stirring for about 80 hours after the start of the test, no chips or flakes were observed in the main 11 rear coating layer, and the toner charge amount remained at 9 μC/a. One hour of stirring in this deterioration tester is equivalent to 5000 copies made in an actual copying machine.

Example 2 In Example 1, instead of steel beads, particle size 80-120
When the same deterioration test as in Example 1 was carried out using the poly(phenylene oxide/phenylene sulfide/sulfone) coated carrier of the present invention except that μ Ferrai 1 Heavies was used, the same results were obtained.

Although the present invention was specifically explained using the above-mentioned Example 11i1j, the same excellent effects can be obtained even when the carrier of the present invention is used together with various toners other than those mentioned above.

Patent applicant Ricoh Co., Ltd. Agent Patent Attorney Hidetake Komatsu 9-

Claims (1)

[Scope of Claims] A carrier for an electrophotographic developer, characterized in that it is coated with poly(phenylene oxide/phenylene sacinate/sulfone) having the following general formula. general formula