Process for preparing extruded foam bodies

A process for preparing an extruded elongate foam body comprising a polystyrene and characterized as having a density of between about 0.9 and about 2.5 pounds per cubic foot which comprises the steps of;

• (A) heat plastifying the polystyrene resin;
• (B) adding from about 6 to about 16 parts by weight based on the weight of the polystyrene of a fluid blowing agent or mixture of blowing agents comprising 1-chloro-1,1-difluoroethane, 1,1,1,2-tetrafluoroethane, or 2-chloro-1,1,1,2-tetrafluoroethane;
• (C) uniformly mixing the blowing agent in the resin under a pressure sufficient to prevent blowing of the resin whereby a blowable resin mixture is obtained;
• (D) extruding the mixture into a region maintained at subatmospheric pressure wherein the blowable resin mixture expands into a foam body;
• and
• (E) cooling the foam body.

A process for preparing an extruded elongate foam body comprising a polystyrene and characterized as having a density of between about 0.9 and about 2 pounds per cubic foot which comprises the steps of

• (A) heat plastifying the polystyrene resin;
• (B) adding from about 6 to about 16 parts by weight based on the weight of the polystyrene of a fluid blowing agent or mixture of blowing agents comprising 1,1,1,2-tetrafluoroethane, 2-chloro-1,1,1,2-tetrafluoroethane, or 1,chloro-1,1-difluoroethane;
• (C) uniformly mixing the blowing agent in the resin under a pressure sufficient to prevent blowing of the resin whereby a blowable resin mixture is obtained;
• (D) extruding the mixture into a region maintained at subatmospheric pressure wherein the blowable resin mixture expands into a foam body;
• and
• (E) cooling the foam body.

A process of preparing an extruded polystyrene resin elongate foam body characterized as having a density of from about 0.9 to about 2 pounds per cubic foot, an average cell size of from about 0.2 to about 0.5 mm. and improved compressive strength which comprises the steps of

• (A) heat plastifying a polystyrene resin;
• (B) incorporating into the plasticized resin, a mixture of fluid blowing agents comprising
• (B-1) 1-chloro-1,1-difluoroethane;
• (B-2) at least one of dichlorodifluoromethane and chlorodifluoromethane;
• and
• (B-3) carbon dioxide;
• (C) uniformly mixing the blowing agents in the resin under a pressure sufficient to prevent blowing of the resin whereby a blowable resin mixture is formed;
• (D) extruding the blowable mixture to a region of subatmospheric pressure wherein the blowable resin mixture expands into a foam body;
• and
• (E) cooling the foam body.