Process for the manufacture of polyurethane foam moldings

In a process for the manufacture of polyurethane foam moldings by the introduction of a polyurethane reactive mixture containing a blowing agent into a mold cavity, by the introduction of a polyurethane reactive mixture containing a blowing agent into a mold cavity, foaming of the reactive mixture, curing and removal from the mold cavity, the improvement comprising:

• (a) dissolving carbon dioxide under pressure in the polyurethane reactive mixture as the blowing agent,
• (b) introducing the reactive mixture into a closed mold cavity,
• (c) maintaining the gas pressure in the mold cavity during the introduction of the reactive mixture at a pressure being such that complete foaming of the reactive mixture is prevented, and
• (d) reducing the gas pressure in the mold cavity, with foaming of the reactive mixture, until the foamed reaction mixture fills the whole of the mold cavity, wherein said gas pressure in the mold cavity during the filling process is at least 50% of the saturation vapor pressure of the carbon dioxide originally dissolved in the reactive mixture.