| abstract |
Processes for producing a polyurethane foam described herein include mixing a physical blowing agent with one or more of an isocyanate-reacting mixture and an isocyanate at a sorption pressure psorp for a time tsorp, reacting the isocyanate-reacting mixture and the isocyanate at a pressure p1 for a time t1, reducing the pressure to a pressure p2, maintaining the pressure at the pressure p2 for a time t2, and reducing the pressure to atmospheric pressure patm. In various embodiments, patm<p2<psat<psorp and psat<p1, where psat is a saturation pressure for the physical blowing agent. |