Patent ID: 9663626
Date: 2017-05-30
CPC Classifications: B01J,C08F,C08J,C08K,C09J

Claim:
1. A process for producing heat-expandable microspheres comprising essentially a shell of thermoplastic resin and a blowing agent encapsulated therein: wherein the process comprises the steps of: dispersing a polymerizable component and the blowing agent in a basic aqueous dispersion medium having a pH ranging from 9.5 to 12 and containing a colloid of a fine-particle metal compound and an amphoteric surfactant, the amphoteric surfactant being a betaine amphoteric surfactant, the betaine amphoteric surfactant being alkylene oxide adduct betaine amphoteric surfactant, where the colloid of the fine-particle metal compound is prepared by a process in which a water soluble metal salt is dissolved in an acidic or neutral aqueous medium and a basic compound is added to the medium, and where an amount of the amphoteric surfactant ranges from 0.001 to 40 parts by weight to 100 parts by weight of the fine-particle metal compound, polymerizing the polymerizable component; and decreasing a pH of the heat-expandable microspheres produced in the polymerization step where the pH is brought down to 6.0 or less.