JPS6356537B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a dry two-component toner used for developing electrostatic latent images. Conventionally, there has been a cascade development method in which an electrostatic image is developed using a so-called two-component electrostatic image developer in which toner particles and carrier particles are mixed, a magnetic brush development method, and toner particles that are charged by friction with a plate-shaped carrier. A method of developing an electrostatic image using a so-called one-component developer consisting of only one component is known. Any of the above-mentioned developers, for example, when repeatedly developing an electrostatic latent image on the same electrophotographic photoreceptor, the binder or coloring agent used in the toner particles on the photoreceptor or carrier This method has disadvantages in that agents and the like adhere and accumulate, impairing the sensitivity of the photoreceptor, causing undesirable stains on the resulting copies, and changing the charging characteristics of the toner particles. Therefore, a developer in which abrasive particles and the like are added and mixed has been proposed. For example, toners in which alkylated silane (silica) is added to the toner (see Japanese Patent Laid-Open No. 46-5782), and lubricants such as polyhydric alcohol esters deposited on the toner surface (Japanese Patent Laid-Open No. 48-47345) (see JP-A-48-47346), phthalic acid and its salts (JP-A-49-60229). (see official bulletin), etc. are known. Among these, when an abrasive is added, as a result of continuous use of the developer, abrasive particles separate from the toner and adhere to the carrier or photoreceptor surface due to electrical force, and the accumulation of these particles causes the carrier to become The charge imparting ability of the developer is reduced, and the developing ability of the developer is lost, and the surface of the photoreceptor may be damaged. Although the above drawbacks can be improved to some extent by controlling the amount of abrasive added to the toner, it is very difficult to determine the appropriate amount. The present invention has been developed in view of the above, and the surface treatment of hard fine powder such as abrasive agent brings the charging series closer to that of the carrier particles, thereby allowing the abrasive particles to electrically adhere to the carrier surface. The purpose of this invention is to prevent the toner from adhering to the photoconductor and to extend the life of the developer without impairing the effect of preventing toner from adhering to the photoreceptor. That is, the present invention provides a toner mainly composed of a thermoplastic resin, which has the general formula However, _R1 :

[expression] or

[Formula] R ₂ to _{R 7} :H, CnH _2o+1 (n=1 to 5) or

A dry two-component toner for developing electrostatic latent images characterized by containing hard fine powder whose surface is treated with a compound represented by the formula: Compounds having the above general formula are useful for bringing the charge series of the hard fine powder closer to that of the carrier material, and the following compounds are representative examples. Hard fine powders to be surface-treated with such compounds include carbides of boron, silicon, titanium, zirconium, and tungsten, nitrides of titanium, boron, and zirconium, aluminum, chromium,
One or more of iron, titanium, zirconium, cerium, magnesium, tin, silicon oxide calcium, barium, and aluminum sulfate or silicate are used. The particle size of these hard fine powders is suitably 1 micron or less. In the present invention, the ratio of the treated hard fine powder to the toner matrix is suitably 0.1 to 2% by weight, and it is also suitable to arrange it on the surface of the toner matrix or in the vicinity thereof. Next, examples will be shown. Example 1 1 part by weight of Al ₂ O ₃ fine powder and 1 part by weight of Eisen Victoria Blue-BH are mixed in toluene, and after the dye is completely dissolved, the toluene is evaporated and returned to powder form. When this powder was mixed with 1% by weight of a commercially available toner and a durability test was conducted using this toner, it was found that this developer was
It exhibited durability of 10,000 sheets/Kg or more, and showed good results with almost no change from the initial stage in terms of image quality, toner fluidity, and toner adhesion to the photoreceptor. Example 2 A durability test was conducted using 1 part by weight of SiO ₂ fine powder and 0.5 part by weight of Fernal Blue-B Subra in the same manner as in Example 1. No change in image quality was observed with this developer even at 15,000 sheets/Kg. Good results were also obtained regarding toner fluidity and toner adhesion to the photoreceptor. Comparative Example When 1 wt% of SiO ₂ fine powder was directly mixed into a commercially available toner and a durability test was conducted in the same manner as in Example 1, this developer deteriorated after 1000 sheets/Kg.

Claims (1)

[Claims] 1. In a two-component toner mainly composed of a thermoplastic resin, the general formula However, R ₁ : [Formula] or [Formula] R ₂ to _{R 7} : H, CnH _2o+1 (n=1 to 5) or [Formula] A dry two-component toner for developing electrostatic latent images.