Post heating of cellulose-based expandable microspheres

Abstract

The invention relates to storage stable thermally expandable microspheres comprising a polymeric shell surrounding a hollow core, wherein the hollow core comprises a blowing agent, and the polymeric shell comprises a carboxylate-functionalised cellulose, wherein the microspheres retain at least 80% of the original weight of blowing agent encapsulated in the microspheres after six months of storage under ambient conditions. The invention further relates to a process for preparing storage stable thermally expandable microspheres comprising a polymeric shell surrounding a hollow core, wherein the hollow core comprises a blowing agent, and the polymeric shell comprises a carboxylate-functionalised cellulose, the method comprising the following steps: (i) preparing thermally expandable microspheres comprising a polymeric shell surrounding a hollow core, wherein the hollow core comprises a blowing agent, and the polymeric shell comprises a carboxylate-functionalised cellulose; and (ii) subjecting the thermally expandable microspheres obtained in step (i) to a post heating treatment by heating the thermally expandable microspheres to a temperature of at least 40° C.

Dependencies are inferred from the claim text.