The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 22, 2001
Filed:
Nov. 22, 1999
Valery Pavlyuchenko, St. Petersburg, RU;
Nina Byrdina, St. Petersburg, RU;
Sergey Ivanchev, St. Petersburg, RU;
Mikael Skrifvars, Helsinki, FI;
Erkki Halme, Helsinki, FI;
Hanna Laamanen, Espoo, FI;
Jukka Koskinen, Espoo, FI;
Neste Chemicals OY, Porvoo, FI;
Abstract
A method for the preparation of latexes with hollow polymer particles useful as opacifying agents. The process comprises the preparation of hollow polymer particle latex by emulsion copolymerization with water soluble initiator and anionic surfactant as follows: a) preparation of seed latex of copolymer containing methyl methacrylate and methacrylic acid; b) preparation of latex of highly carboxylated copolymer containing methyl methacrylate and a cross-linking agent and optionally a vinyl aromatic compound; c) using highly carboxylated latex synthesized at stage b) in the preparation of the intermediate shell comprising a copolymer of methyl methacrylate, acrylic acid ester, a cross-linking agent and optionally vinyl aromatic compound, said intermediate shell copolymer having a glass transition temperature below 80° C.; d) swelling the particles prepared at stage c) by addition of volatile basic compound; e) preparation of a hard shell on the swollen expanded particles comprising a copolymer of vinyl aromatic compound, acrylonitrile and/or methyl methacrylate, and cross-linking agent, said hard shell having a glass transition temperature above 80° C.; and f) optional preparation of an external shell.