Matsumoto Yushi-seiyaku Co., Ltd.

Bridgestone Corporation

Takayuki Aoki

Kenichi Kitano

Toshiaki Masuda

Katsushi Miki

Ichiro Takahara

Hiroyuki Teratani

Takeshi Inohara

Satoshi Kawanami

Takeyoshi Fukuda

A method that produces heat-expandable microspheres includes the use of a shell of thermoplastic resin and a non-fluorine blowing agent encapsulated therein having a boiling point not higher than the softening point of the thermoplastic resin. The method includes a step of dispersing an oily mixture containing a polymerizable component, the blowing agent, and a polymerization initiator containing a peroxydicarbonate in an aqueous dispersing medium to polymerize the polymerizable component contained in the oily mixture. The resultant heat-expandable microspheres have a shell which is less apt to become thinner than its theoretical value, contain minimum amount of resin particle inside their shell, and have excellent heat-expanding performance.

Heat-expandable microspheres and a process for producing the same

The present invention provides heat-expanded microspheres having high packing efficiency, and a production method thereof. The heat-expanded microspheres are produced by expanding heat-expandable microspheres, which comprise shell of thermoplastic resin and a blowing agent encapsulated therein having a boiling point not higher than the softening point of the thermoplastic resin and have an average particle size from 1 to 100 micrometer, at a temperature not lower than their expansion initiating temperature, and the heat-expanded microspheres result in a void fraction not higher than 0.70.

Thermally expanded microspheres and a process for producing the same

A method that heat-expandable microspheres includes the use of a shell of thermoplastic resin and a non-fluorine blowing agent encapsulated therein having a boiling point not higher than the softening point of the thermoplastic resin. The method includes, a step of dispersing an oily mixture containing a polymerizable component, the blowing agent, and a polymerization initiator containing a peroxydicarbonate in an aqueous dispersing medium to polymerize the polymerizable component contained in the oily mixture. The resultant heat-expandable microsphres have a shell which is less apt to become thinner than its theoretical value, contain minimum amount of resin particle inside their shell, and have excellent heat-expanding performance.

Heat-expandable microspheres include a shell of thermoplastic resin and a blowing agent encapsulated therein having a boiling point not higher than the softening point of the thermoplastic resin, have a maximum expanding ratio not lower than 50 times, and are thermally expanded into hollow particulates having a repeated-compression durability not lower than 75 percent. The method of producing the heat-expandable microspheres includes the steps of dispersing an oily mixture containing a polymerizable component and the blowing agent in an aqueous dispersing medium containing a specific water-soluble compound and polymerizing the polymerizable component contained in the oily mixture.

Heat-expandable microspheres, method for producing the same, and application thereof

Heat-expanded microspheres having high packing efficiency are produced by expanding heat-expandable microspheres, which include a shell of thermoplastic resin and a blowing agent encapsulated therein having a boiling point not higher than the softening point of the thermoplastic resin and have an average particle size from 1 to 100 micrometer, at a temperature not lower than their expansion initiating temperature, and the heat-expanded microspheres result in a void fraction not higher than 0.70.

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Yao, Japan

Takayuki Aoki