Patent ID: 8557884

Claim:
A method of increasing the cell orientation ratio in the x/z direction of a rigid polymer foam material comprising: providing a device capable of producing a rigid polymer foam material; introducing a thermoplastic polymer resin to said device; heating said thermoplastic polymer resin above its glass transition temperature and melting point; incorporating one or more blowing agents into said thermoplastic polymer resin at a first pressure to form a gel, said first pressure being sufficient to prevent pre-foaming of said gel; cooling said gel to a die melt temperature; and extruding the gel through a die gap of the device to a region of lower die pressure; wherein said gel is extruded through said die gap onto a conveyor such that the gel grows quicker in the x-direction relative to the z-direction to form the polymer foam material, wherein said x-direction is defined as the extruded direction of the polymer foam material and wherein said z-direction is defined as the vertical thickness direction of the polymer foam material wherein the polymeric foam material comprises greater than about 95% closed cells.