Mitsui Toatsu Chemicals, Incorporated

Kousuke Someya

Takeshi Yanagihara

Futoshi Hoshino

Akihiro Yamazaki

Makoto Nakano

Junko Morita

A multi-shell emulsion particle of dry state structure having one or more of penetrating pore(s) connecting the surface layer of the particle with the interior of the particle and having a particle diameter of from 0.1 to 5.0.mu. preferably from 0.1 to 1.2.mu.. The particles can be prepared by carrying out emulsion polymerization of a vinyl monomer (a) containing from 5 to 80% by weight of an unsaturated carboxylic acid to obtain a polymer (A), forming a polymer (B) in the presence of a particle consisting of the resultant polymer (A) while adding a vinyl monomer (b) in an amount of 10 times by weight or less and at a rate of 3 times by weight per hour or more for the weight of the polymer (A), and treating the resultant multi-shell emulsion polymer with an alkaline material to neutralize and swell the polymer (A); or, after the neutralization treatment, further forming a polymer (C) by adding and emulsion-polymerizing a vinyl monomer (c) in an amount of 20 times by weight or less for the total weight of the polymer (A) and polymer (B). The emulsion particle is useful as a component of resin compositions for paints, paper-coating and heat-sensitive recording materials.

Multi-shell emulsion particle

A multi-shell emulsion particle of dry state structure having one or more of penetrating pore(s) connecting the surface layer of the particle with the interior of the particle and having a particle diameter of from 0.1 to 5.0.mu. preferably from 0.1 to 1.2.mu.. The particles can be prepared by emulsion polymerization of a vinyl monomer (a) containing from 5 to 80% by weight of an unsaturated carboxylic acid to obtain a polymer (A), forming a polymer (B) in the presence of a particle consisting of the resultant polymer (A) while adding a vinyl monomer (b) in an amount of 10 times by weight or less and at a rate of 3 times by weight per hour or more for the weight of the polymer (A), and treating the resultant multi-shell emulsion polymer with an alkaline material to neutralize and swell the polymer (A); or, after the neutralization treatment, further forming a polymer (C) by adding and emulsion-polymerizing a vinyl monomer (c) in an amount of 20 times by weight or less for the total weight of the polymer (A) and polymer (B). The emulsion particle is useful as a component of resin compositions for paints, paper-coating and heat-sensitive recording materials.

A cored multi-shell emulsion particle consisting of a core particle, a void layer existing in the exterior of the core particle and a shell layer, each of which has a diameter of .phi., d and D, respectively, and the ratio of .phi., d and D is in the following range.

Cored multi-shell emulsion particle

A synthetic resin emulsion whose polymer particles are solid core-shell particles in which form pores spontaneously upon drying is produced by the steps of preparing as core particles from 2 to 60 parts by weight of polymer (A) by emulsion polymerization of from 10 to 80 parts by weight of acrylate ester (a.sub.1) having an alkyl group of from 1 to 3 carbon atoms and from 90 to 20 parts by weight another of vinyl-type monomer (a.sub.2) copolymerizable therewith, forming a shell of a polymer (B) on the surface of the core particles of polymer (A) by emulsion polymerization in the presence thereof of from 98 to 40 parts by weight of vinyl-type monomer (b), different from polymer (a.sub.1) and successively hydrolyzing the core portion of the particles with an alkaline material. Organic pigments prepared from the synthetic resin emulsion can improve the hiding power, brightness, gloss and other properties of articles coated therewith.

Synthetic core-shell particle resin emulsion, process for producing and

A thermosensitive recording paper is disclosed useful for thermosensitive recording which comprises a substrate, a thermosensitive recording layer and an undercoat layer interposed therebetween which contains 10 to 40 parts of a binder and 60 to 90 parts by weight of crosslinked polymer microparticles having a particle diameter of 0.2 to 5.0 .mu.m and a ratio of weight average diameter to number average diameter of 2.0 or less.

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Yokohama, Japan

Kousuke Someya