Abstract 1. A PROCESS FOR FORMING A LOW DENSITY FOAMED EXTRUDATES COMPRISING: ADMIXING AN EXPANDING AGENT WITH A THERMOPLASTIC POLYMER; RENDERING SAID THUS FOAMED ADMIXTURE INTO A MOLTEN CONDITION; AND MAINTAINING SAID POLYMER MIXTURE IN SAID MOLTEN CONDITION UNDER SUFFICIENT PRESSURE SO SUBSTANTIALLY NO EXPANDION TAKES PLACE WITHIN AN EXTRUDER; THEREAFTER PASSING SAID MOLTEN ADMIXTURE THROUGH AN ANNULAR CHANNEL OF A DIE HAVING A GRADUALLY INCREASING CROSS-SECTIONAL AREA SO AS TO ALLOW SAID POLYMER TO GRADUALLY EXPAND AS IT MOVES TOWARD THE DIE END; AND UPON EXITING FROM THE DIE GRADUALLY EXPANDING SAID THUS FORMED AND EXPANDED ANNULAR EXTRUDATE RADIALLY OUTWARDLY BY PASSING THE SAME OVER A MANDREL WHICH HAS STRAIGHT WALLS DIVERGING TOWARD A DOWNSTREAM END THEREOF, SAID MANDREL EXTENDING BEYOND AN END OF SAID ANNULAR CHANNEL A DISTANCE EQUAL TO 1 TO 20 TIMES A DIAMETER OF SAID MANDREL, AN OUTER SURFACE OF SAID EXTRUDATE NOT BEING IN CONTACT WITH ANY FORMING SURFACE DURING THIS STEP.
A PROCESS FOR FORMING A LOW DENSITY FOAMED EXTRUDATES COMPRISING: ADMIXING AN EXPANDING AGENT WITH A THERMOPLASTIC POLYMER; RENDERING SAID THUS FOAMED ADMIXTURE INTO A MOLTEN CONDITION; AND MAINTAINING SAID POLYMER MIXTURE IN SAID MOLTEN CONDITION UNDER SUFFICIENT PRESSURE SO SUBSTANTIALLY NO EXPANDION TAKES PLACE WITHIN AN EXTRUDER; THEREAFTER PASSING SAID MOLTEN ADMIXTURE THROUGH AN ANNULAR CHANNEL OF A DIE HAVING A GRADUALLY INCREASING CROSS-SECTIONAL AREA SO AS TO ALLOW SAID POLYMER TO GRADUALLY EXPAND AS IT MOVES TOWARD THE DIE END; AND UPON EXITING FROM THE DIE GRADUALLY EXPANDING SAID THUS FORMED AND EXPANDED ANNULAR EXTRUDATE RADIALLY OUTWARDLY BY PASSING THE SAME OVER A MANDREL WHICH HAS STRAIGHT WALLS DIVERGING TOWARD A DOWNSTREAM END THEREOF, SAID MANDREL EXTENDING BEYOND AN END OF SAID ANNULAR CHANNEL A DISTANCE EQUAL TO 1 TO 20 TIMES A DIAMETER OF SAID MANDREL, AN OUTER SURFACE OF SAID EXTRUDATE NOT BEING IN CONTACT WITH ANY FORMING SURFACE DURING THIS STEP.
Claim 2
Dependent Claim
156 words
A PROCESS FOR FORMING A LOW DENSITY FOAMED EXTRUDATES COMPRISING: ADMIXING AN EXPANDING AGENT WITH A THERMOPLASTIC POLYMER; RENDERING SAID THUS FOAMED ADMIXTURE INTO A MOLTEN CONDITION; AND MAINTAINING SAID POLYMER MIXTURE IN SAID MOLTEN CONDITION UNDER SUFFICIENT PRESSURE SO SUBSTANTIALLY NO EXPANDION TAKES PLACE WITHIN AN EXTRUDER; THEREAFTER PASSING SAID MOLTEN ADMIXTURE THROUGH AN ANNULAR CHANNEL OF A DIE HAVING A GRADUALLY INCREASING CROSS-SECTIONAL AREA SO AS TO ALLOW SAID POLYMER TO GRADUALLY EXPAND AS IT MOVES TOWARD THE DIE END; AND UPON EXITING FROM THE DIE GRADUALLY EXPANDING SAID THUS FORMED AND EXPANDED ANNULAR EXTRUDATE RADIALLY OUTWARDLY BY PASSING THE SAME OVER A MANDREL WHICH HAS STRAIGHT WALLS DIVERGING TOWARD A DOWNSTREAM END THEREOF, SAID MANDREL EXTENDING BEYOND AN END OF SAID ANNULAR CHANNEL A DISTANCE EQUAL TO 1 TO 20 TIMES A DIAMETER OF SAID MANDREL, AN OUTER SURFACE OF SAID EXTRUDATE NOT BEING IN CONTACT WITH ANY FORMING SURFACE DURING THIS STEP.