THERMOFORMABLE POLYPROPYLENE FOAM SHEET

A process for making a polymer foam sheet, which comprises (i) extruding through an annular extrusion die a foamable composition comprising at least one polypropylene polymer and at least one blowing agent , at a pressure, temperature, and extrusion rate sufficient to prevent foaming of the composit...

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Bibliographische Detailangaben
Hauptverfasser:	SUH, KYUNG W, CHRISTENSON, CHRISTOPHER P, PARK, CHUNG P, TUSIM, MARTIN H, CORNELL, MARTIN C
Format:	Patent
Sprache:	eng ; fre
Schlagworte:	AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F,C08G AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING CHEMISTRY COMPOSITIONS BASED THEREON GENERAL PROCESSES OF COMPOUNDING LAYERED PRODUCTS LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT ORNON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM METALLURGY ORGANIC MACROMOLECULAR COMPOUNDS PERFORMING OPERATIONS SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDEDFOR SHAPING OR JOINING OF PLASTICS THEIR PREPARATION OR CHEMICAL WORKING-UP TRANSPORTING VEHICLES IN GENERAL VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISEPROVIDED FOR WORKING OF PLASTICS WORKING OF SUBSTANCES IN A PLASTIC STATE, IN GENERAL WORKING-UP
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Beschreibung
Zusammenfassung:	A process for making a polymer foam sheet, which comprises (i) extruding through an annular extrusion die a foamable composition comprising at least one polypropylene polymer and at least one blowing agent , at a pressure, temperature, and extrusion rate sufficient to prevent foaming of the composition prior to exiting the die, under condition s sufficient to form a foam tube having a density of at least (16) kg/m3 and no greater than 200 kg/m3, an open cell content of less than 70 percent, a circumference of at least 1 meter, and a foam thickness of at least 2 mm and no greater than 25 mm, wherein the blowing agent is used in an amount of from 0.2 to 4.5 moles per kg of polymer, (ii) allowing the foam to cool to a temperature below the melt temperature of the polypropylene, and (iii) cutting the tube of foam along its radius to form a foam sheet, wherein at least 70 percent by weight of the polymer in such sheet is a polypropylene having a melt strength in the range of from 25 to 60 cN when measured at 190 .degree.C.