Plastic and nonmetallic article shaping or treating: processes – Pore forming in situ – Composite article making
Patent
1986-09-29
1991-03-19
Simmons, David
Plastic and nonmetallic article shaping or treating: processes
Pore forming in situ
Composite article making
264 53, 264 54, 264143, B29C 6720
Patent
active
050008919
ABSTRACT:
A process for manufacturing expandable polystyrene pellets having a bulk density of about 36 lbs/cubic foot which upon expansion results in expanded articles having a bulk density of about 0.8 lbs/cubic foot and having substantiallly uniform cell formation is an interior portion thereof. The process for manufacturing the pellets includes the steps of: (a) mixing virgin polystyrene beads having a molecular weight of less than about 200,000 with an effective minor amount of a nucleating agent to provide an extrusion mixture; (b) introducing the extrusion mixture into an extruder and extruding a heat plasticized mass to form an unexpanded extrudate in filamentary form; (c) drawing the extrudate to provide a drawn extrudate having a substantially continuous, gas impervious skin (d) immediately cooling the drawn extrudate to a temperature below the vaporization temperature of the vaporizable expanding agents; (e) cutting the cooled drawn extrudate into pellets; and (f) aging the pellets by exposure of the pellets to ambient atmospheric conditions.
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Kuhns Allan R.
Simmons David
LandOfFree
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