Mita Industrial Co., Ltd.

Nippon Zeon Company, Ltd.

Sumitomo Seika Chemicals Co., Ltd.

Masayoshi Okubo

Masami Tsujihiro

Shigeki Hamamoto

Toshiro Tokuno

Hirotsugu Kawata

Kiyoshi Yamaguchi

Tsunetaka Matsumoto

The present invention provides a resin particle having many recesses on the surface thereof, which has solvent resistance and heat resistance. More specifically, the present invention provides a resin particle having many recesses on the surface thereof which is obtained by using a seed particle, wherein a seed particle component in the resin particle has a crosslinked structure. Since the resin particle having many recesses on the surface thereof of the present invention is excellent in solvent resistance and heat resistance in addition to light diffusing properties, the resin particle is appropriate for use, for example, in not only cosmetics containing silicone oil and the like in a preparation, a light diffusing film and a light diffusing sheet prepared by dispersing resin particles as a light diffusing agent in an organic solvent such as 2-butanone and the like in a production process, and a light diffusing plate prepared by kneading at a high shear force the resin particles as a light diffusing agent with polystyrene or polymethyl methacrylate and the like which melts at a high temperature of approximately 300&#xb0; C. in a production process.

Resin particle having many recesses on the surface thereof

In a dispersion system comprising seed polymer particles and a monomer, the solubility of the monomer is reduced by such means as addition of water, whereby the monomer is precipitated and absorbed in the seed polymer particles, and in this state, the monomer absorbed in the seed polymer particles is selectively polymerized. Namely, according to the present invention, the decrease of the solubility of the monomer in the dispersion system is utilized for absorption of the monomer in the seed polymer particles, and polymer particles having an increased particle size can be prepared in a short time at a high efficiency.

Process for preparation of monodisperse polymer particles having

A process for producing hollow polymer latex particles, which comprises

Process for producing hollow polymer latex particles

Disclosed is a process in which a spherical electrophotographic toner containing a colorant and having a particle size suitable for the electrophotography is directly formed in the polymerization process for formation of a binder resin. If a reaction medium capable of dissolving a monomer but incapable of dissolving a formed polymer is used and polymerization is carried out in the presence of a radical polymerization initiator in the state where the monomer, the colorant and other additives are dissolved or dispersed in the reaction medium, an electrophotographic toner having a desired particle size is obtained. According to this process, the particle size of the colored resin is stably controlled to 1 to 30 .mu.m suitable for a toner in the polymerization process, and the particle size distribution is very sharp.

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Kobe, Japan

Masayoshi Okubo