Expandable microspheres and methods of making and using the same

US8382945B2 · kind B2 · utility

Assignee

• INTERNATIONAL PAPER COMPANY · US

Inventors

• Yaoliang Hong · Mason, US
• Kosaraju Krishna Mohan · Texarkana, US
• Peter M. Froass · Mason, US
• Mark Fagan · Loveland, US
• Christopher D. Anderson · Wescosville, US
• Brian Boyars · Las Vegas, US
• Eric Scott Daniels · Bethlehem, US
• Victoria Laurentia Dimonie · Bethlehem, US
• Edward David Sudol · Bethlehem, US
• Andrew P. Klein · Appleton, US

Key dates

• Filing date: Aug 28, 2009
• Grant date: Feb 26, 2013
• Expiry date: Jul 9, 2030

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10T428/2982
• WIPO field: Macromolecular chemistry, polymers
• WIPO sector: Chemistry

Abstract

Expandable microspheres formed by suspension polymerization using a shot growth method are provided. The microspheres are formed of a continuous, gas impermeable shell surrounding a blowing agent. The shell includes a first polymer layer formed from primary monomers and a second layer that includes a chemically reactive monomer or a high Tg monomer. To form the microspheres, the primary monomers are polymerized in a reaction vessel to an approximate 90% polymerization, at which time a secondary monomer that is either a monomer having a Tg of at least 85° C. or a chemically reactive monomer, is added to the reaction vessel to drive the polymerization reaction to completion. The outer layer thus contains either a larger amount of the high Tg monomer or a chemically reactive monomer that possesses the ability to covalently bond a cationic species. The microspheres may be used in papermaking processes to increase the paper bulk.