JPS58207054A - Carrier for developing electrostatic latent image - Google Patents

Abstract

PURPOSE:To obtain an electrostatic latent image developing carrier high in coat film strength and capable of giving image quality stabilized for a long time, by coating a carrier core material with a silicone resin contg. SiC as an inorg. reinforcing filler. CONSTITUTION:The carrier for developing an electrostatic latent image is obtained by coating the carrier core material, such as Co, Fe, Ni, brass, or glass, with a liquid coating contg. a silicone resin and SiC fine powder having about 0.2mum average particles diameter as a reinforcing filler in a fluidized bed coating apparatus. A developer is obtained by mixing 3pts.wt. known toner with 100pts. wt. of thin carrier. The carrier thus obtained is long in life, little made spent by the toner, and not impaired in characteristics of the developer due to peeling and abrasion of the coated film.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dry developer used for visualizing an electrostatic latent image formed by electrophotography, electrostatic recording, electrostatic printing, etc. Regarding agent carriers.

So-called two-component dry developers comprising a mixture of carrier particles and dove particles have been well known. In this two-component dry developer, minute toner particles are held on the surface of relatively large carrier particles by electric force generated by friction between both particles, and when brought close to an electrostatic latent image, an electrostatic latent image is formed. The attraction force in the direction of the latent image towards the toner particles due to the electric field formed by the 1-toner particles overcomes the bonding force between the toner particles and the carrier particles, and the 1-toner particles are attracted and adhered onto the electrostatic latent image. The electrostatic latent image is visualized. The developer is used repeatedly while replenishing the l-ner consumed by development.

Therefore, during long-term use, the developer must always keep the toner particles at the desired polarity and have a sufficient amount of charge (frictional electrification). However, conventional developers or mechanical collisions such as collisions between particles and the developing machine, or heat generation due to these (- A 1-Henner film is formed on the carrier surface, so-called spent formation occurs, and the charging characteristics of the carrier deteriorate with time of use, causing the developer to The whole thing needs to be replaced.

In order to prevent such spent IL, 4-
Various methods have been proposed for coating the surface of 1I and 7 with various resins, but none have yet been found to be satisfactory. For example, K1/Rear coated with resins such as styrene/methacrylate 1 - copolymer, styrene small copolymer, etc. have excellent charging characteristics, but the critical surface tension of the surface is relatively high, and as a result of repeated copying, Otherwise, the lifespan of the developer is not very long because of the occurrence of liss venting. In addition, carriers coated with tetrafluoroethylene ethylene polymer have low surface tension, so it is difficult for toner to become spent, but since tetrafluoroethylene polymer is located on the most negative side of the triboelectrification series, It cannot be used when attempting to charge to one polarity. Furthermore, as a material having low surface tension, a chitria coated with a coating layer containing a silicone resin has been proposed. For example, unsaturated silicone resin, organosilicon, silanol, etc. are mixed with styrene acrylic resin to coat the surface of the carrier (US Pat. No. 3,562,533).
No.); carrier whose surface is coated with polyphenylene resin and organosilicone terpolymer resin (US Pat. No. 3,847,127); styrene-acrylate ~
Methacrylate resin, organosilane, silanol,
Ki coated with C surface such as siloxane!・Rear (US Pat. No. 3,627,522): A carrier coated with a coating layer containing a silicone state resin and a nitrogen-containing resin having positive charging characteristics (Japanese Patent Application Laid-open No. 127,567/1989); and resin modification Examples include Kytria (Japanese Patent Application Laid-open No. 157751/1983) whose surface is coated with a silicone resin.

However, the silicone resin used for these coatings itself has low mechanical strength, so if strong agitation is used, such as in a high-speed copying machine, or agitation in the development area for a long time, the carrier particles may disintegrate into the development area. If the particles collide with the inner wall or the surface of the photoreceptor, or if the particles easily hit, the silicone resin coating layer will be worn away and peeled off over time, and frictional charging will occur from the charging between the toner and the silicone resin. Since the charge changes to the toner and the core material of Kitria, the charge of the developer does not remain constant and image quality deteriorates.

In order to improve these drawbacks, methods have been proposed, such as adding reinforcing fillers with excellent wear resistance to silicone resins, but conventional fillers do not cause friction with the tonneau. The actual situation is that charging characteristics are impaired and satisfactory results have not yet been obtained.

The present invention has been made with the aim of solving the above-mentioned conventional drawbacks. Specifically, the present invention has been made with the aim of solving the above-mentioned conventional drawbacks. Specifically, the present invention has been made to provide a silicone resin with excellent abrasion resistance without impairing the strong effect of preventing toner from becoming spent. The purpose of this product is to provide a V-Yaria for electrostatic latent image developers whose surface is coated with a coating layer, and it is believed that this will allow the developer to be used for a long period of time without deteriorating its properties and to be stable. The object of the present invention is to provide a developer carrier that provides high image quality.

That is, the present invention provides an electrostatic latent image developer carrier whose surface is coated with a silicone resin containing an inorganic reinforcing filler, wherein the inorganic reinforcing filler is silicon carbide. The present invention provides a carrier for the drug.

To explain the present invention in more detail below, the silicone resin used in the present invention may be any conventionally known silicone resin. Although silicone resin is mentioned, it is easily understood that other silicone resins can also be used in view of the essence of the present invention.

R: Honken atom, halogen atom, hydroxy group, me1-1
Examples of commercially available silicone resins with silyl groups, 01-4 lower alkyl groups, or noenyl groups include Shin-Etsu Chemical's KR271, KR255, and KR152, and Toshishiri 1.
- made by S R2400, Stl 840, S R2
There is 406 etc.

6- In the present invention, the carrier core material coated with silicone resin includes sand, cobalt, iron, steel, nickel, zinc, aluminum, brass, with an average particle size of 20 to 1000μ, preferably 50 to 500μ. Conventionally used materials such as nonmetals such as glass, metals, and metal alloys are widely used. The silicone resin coating method involves dissolving the resin in a solvent and applying it to the surface of the core material by conventionally known means such as spraying.
Just make it.

To add silicon carbide to the silicone resin, add it to the silicone resin solution and disperse with an appropriate mixer,
Just apply it to the kit/rear surface. The silicon carbide used in the present invention increases the strength of the silicone resin coating,
In order to provide stable image quality over a long period of time, there is no change in the triboelectric charging properties of the silicone resin-coated carin as with conventional fillers.

The material used with the Kiria of the present invention is a material obtained by a conventionally known method, specifically a resin component, and a coloring such as carbon black, which is usually necessary for forming a visible image. The ingredients are thoroughly mixed, milled using a hot roll mill, cooled to 141°C, solidified, pulverized, and classified.

When fixing is carried out by constant fixing with a hot roller, the surface of the toner particles is 0.2.~2Φ- for one pair of luna.
% of low molecular weight polypropylene, x4, L polyethylene, etc. can be used. Toners to which particles of low molecular weight small aggregates with excellent mold releasability are adhered or thermally fused can be used.

It is preferred that the amounts of toner and toner used be such that the toner particles adhere to the surface of the 1197 particles of silicone resin and occupy 30 to 90% of the surface area.

Hereinafter, the present invention will be explained by giving examples.

Example 1 1. Homogenize the silicone white resin coating solution according to the prescribed recipe 3
After dispersing for 0 minutes, the dispersion was coated on the surface of 5 kg of 100μ iron oxide powder using a fluidized bed coating device to obtain a silicone resin coated layer.

Silicone resin (Shin-Etsu Chemical KR2'l0) 2 Coarse silicon carbide (average particle size o, 23μ) 10g Toluene
2kg F carrier 100 parts by weight, 2.5% weight ratio C toner (Lini) -
6600) to make a developer and use it.
Although 100,000 copies were made using a machine (FT6600 manufactured by Ricohe), there was no change in the thickness of the silicone resin coating and no change in image quality as shown in Figure 1a.

Comparative Example 1 A developer was prepared in the same manner as in Example 1 except that silicon carbide was removed from the silicone resin solution formulation in Example 1.
When a single copy test was conducted, as shown in Figure 1, the thickness of the silicone resin coating decreased with the number of copies, and the quality of the image also deteriorated.

Example 2 A silicone resin solution with the following recipe was dispersed in a small fir for 1-9-4-30 minutes, and then 5 kg of 70μ iron oxide powder was added.
The surface of F was coated using a fluidized bed coating device to obtain a silicone resin-coated chitria.

Silicone resin (manufactured by Toshi Silicone, S R2400) 1.2 kg Carbonized//Iron (average particle size o, 15 μ > 1 og Torr l) 3.0% A by weight per 100 Φ part of the carrier
'J O'('l-su-(') ::J-1
' VVU 6600) When a developer was prepared and 100,000 sheets were printed in the same manner as in Example 1, the thickness of the silicone resin coating changed as shown in Figure 2 a. The image quality was stable.

Comparative Example 2 A silicone resin-coated carrier was cut using the silicone resin melt of Example 2 but excluding silicon carbide, and the silicone resin-coated carrier of Example 1 was
As shown in Figure 2, the number of copies and the sharpness of the silicone resin coating decreased, and the image quality increased. Along with this, it deteriorated.

10- As mentioned above, the coating film of the carrier of the present invention has excellent abrasion resistance, so even if copying is performed for a long time, the coating film will not peel off or wear out and impair the properties of the developer. Always provide stable image quality.

[Brief explanation of drawings]

Figures 1 and 2 show the changes in the thickness of the silicone resin coating on the surface of Kiki rear when 100,000 copies were made using the developer containing the carrier of the present invention and the four comparative Nyrias. This is a graph. Patent applicant Ricoh Co., Ltd. agent Patent attorney Hide Komatsu Hatake

Claims (1)

[Claims] A carrier for an electrostatic latent image developer whose surface is coated with a silicone resin containing an inorganic reinforcing filler, wherein the inorganic reinforcing filler is silicon carbide.