Patent ID: 6342172
Filing Date: 2002-01-29
Classification: B29C,B29K,Y10T

Abstract:
A process for forming a foamed composite, the process comprising the steps of:(a) forming an extrusion mass comprising: (i) a vinyl polymer composition; (ii) wood fibers; and (iii) a foaming agent capable of foaming the polymer composition; (b) introducing the extrusion mass into an extruder path comprising a barrel, at least one screw drive, the path additionally comprising a moisture vent positioned between a first heated zone having a temperature of about 165 to 190Â° C. and a second heated zone having a temperature of about 165 to 190Â° C., the extrusion path leading to a mandrel and a shaping die comprising a calibration gauge; (c) heating the extrusion mass to at least 100Â° C. before reaching the moisture vent; (d) removing moisture but not the foaming agent from the extrusion mass as the extrusion mass passes the moisture vent; (e) forming a molten extrusion mass by heating the extrusion mass above its melting point; (f) exceeding the decomposition temperature of the foaming agent after the extrusion mass passes the moisture vent and melts but before the extrusion mass enters the die; (h) forming a foamed member from the extrusion mass in the die; and (i) contacting a surface of the solid foamed member in the gauge with a liquid, forming a member with at least a portion of its surface having a smooth hard character.