Patent ID: 7318720
Filing Date: 2008-01-15
Classification: B29C,B29K,Y10T

Abstract:
1. An extrusion die assembly for the continuous production of a composite profile comprising composite compound comprising thermoplastic resin and cellulosic fiber and having a desired cross-section and an exterior surface, wherein the die assembly has an axis oriented from an upstream end to a downstream end, said die assembly comprising: a. a flow passage which results in a generally balanced flow of the composite compound from an upstream die assembly inlet to a downstream die assembly outlet, wherein the die assembly inlet and outlet are displaced along said axis; b. a compression zone of the flow passage having an inlet and an outlet, wherein the compression zone corresponds to at least a portion of the upstream end of the flow passage and the compression zone inlet corresponds to the die assembly inlet; c. a transition zone of the flow passage having an inlet and an outlet, wherein the transition zone inlet corresponds to the compression zone outlet; d. a converging die zone of the flow passage having an inlet and an outlet, wherein the converging die zone inlet corresponds to the transition zone outlet and the converging die zone outlet generally corresponds to the cross-section of the composite profile; e. a die land having an inlet and an outlet, wherein the die land corresponds to at least a portion of the downstream end of the flow passage, the die land inlet corresponds to the converging die zone outlet, the die land outlet corresponds to the outlet of the die assembly and the cross-section of die land outlet corresponds to the cross-section of the composite profile; f. a compression section, a transition section, a converging die section and a die land section of the die assembly, wherein the compression, transition, converging die and die land sections comprise sections of the die assembly obtained by passing a series of parallel planes perpendicular to said axis through the die assembly at the inlets and outlets of the compression, transition and converging die zones and the die land, respectively, wherein the die land section forms the exterior surface of the composite profile; g. cooling means positioned in the die land section to maintain the temperature of the die land section at a temperature below the melting point temperature of the thermoplastic resin; and h. heating means to maintain the temperature of the compression, transition and converging die sections at a temperature above the melting point temperature of the thermoplastic resin.