Patent ID: 9145477
Filing Date: 2015-09-29
Classification: B29C,B29K,C08J

Abstract:
1. A process for preparing thermoplastic polymer foam, the process comprising: a. providing a thermoplastic polymer selected from styrenic polymers and (meth)acrylic polymers; b. compounding with the thermoplastic polymer one or more than one additive having a Total Hansen Solubility Parameter that differs from that of carbon dioxide by less than 2 where the total concentration of said one or more than one additive is 1.5 weight-parts or less and 0.01 weight-parts or more based on 100 weight-parts of thermoplastic polymer to form a thermoplastic polymer compound; c. incorporating into the thermoplastic polymer at an initial pressure sufficient to prevent foaming, either before or after step (b), a blowing agent comprising 20 mole-percent or more carbon dioxide based on total moles of blowing agent; and d. reducing the pressure on the thermoplastic polymer compound thereby allowing the blowing agent to expand the thermoplastic polymer into thermoplastic polymer foam having a porosity of 70% or more and at least one of (i) an average cell size of 200 nanometers or less; and (ii) a nucleation density of at least 1×10 wherein the thermoplastic polymer and thermoplastic polymer foam are free of triblock copolymers and polymers derived from 2-hydrocarbyl-3,3-bis(hydroxyphenyl)phthalimidine compounds and wherein the pressure reduction in step (d) occurs at a rate that is 7,500 mega Pascals per second or less.