EP0112058A2
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EP
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A method of and apparatus for forming a polymeric sheet structure having comparatively high density skin layers and a comparatively low density core layer
Assignee: Mobil Oil AS
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Filing: 1983-11-17
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Granted: —
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Expires: 2003-11-17
Abstract
Abstract U7 In a method and apparatus for producing a foamed polymeric sheet having comparatively high density skin layers and a comparatively low density core layer, molten polymer containing a foaming agent is extruded from a die 18 into a post-extrusion region 22 defined by the die 18 and a spaced pair of rotating chill rolls 24 which are spaced from the die 18. The post-extrusion region 22 is maintained at a pressure sufficient to at least inhibit expansion of the foaming agent through the use of cooled sealing elements 26 which occupy a substantial portion of the space between the die 18 and the chill rolls 24, and are spaced from the chill rolls 24. The rolls 24 and the sealing elements 26 are cooled so that molten polymer in the space between the sealing elements and the rolls becomes solidified, completing the seal. The chill rolls 24 are maintained at a temperature below the temperature of the molten polymer to aid the skin formation on the surfaces of the polymer. If desired, the polymer can pass directly from the chill rolls into a water bath.
Inventors
- 👤 David Emil Johnson
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-04 18:10
CPC Classifications
B; B29; B29C; B29C44/00; B29C44/20; B29C44/22; B29C44/34; B29C44/36; B29C44/46; B29C44/50; B29C44/505; B29C48/00; B29C48/03; B29C48/07; B29C48/08; B29C48/25; B29C48/30; B29C48/35; B29L; B29L2007/00; Y; Y10; Y10S; Y10S264/00; Y10S264/05
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
169 words
A method of forming a polymeric sheet structure having comparatively high density skin layers and a comparatively low density core layer comprising: (a) extruding molten polymer containing a foaming agent through a die into a post extrusion region defined by the die and two spaced rotating chill rolls which are spaced from the die; (b) maintaining the post extrusion region at a pressure sufficient to at least inhibit expansion of the foaming agent with cooled sealing means which occupy a substantial portion of the space between the die and the rolls and are spaced from the rolls, the rolls and the sealing means being cooled so that molten polymer in the space between the rolls and the sealing means is solidified; (c) transporting the molten extruded polymer between, into contact with and through the chill rolls, the chill roll surfaces being maintained at a temperature lower than the solidification temperature of the polymer; and (d) transporting the polymer from between the chill rolls to a region of lower pressure.
Claim 2
Independent Claim
169 words
A method of forming a polymeric sheet structure having comparatively high density skin layers and a comparatively low density core layer comprising: (a) extruding molten polymer containing a foaming agent through a die into a post extrusion region defined by the die and two spaced rotating chill rolls which are spaced from the die; (b) maintaining the post extrusion region at a pressure sufficient to at least inhibit expansion of the foaming agent with cooled sealing means which occupy a substantial portion of the space between the die and the rolls and are spaced from the rolls, the rolls and the sealing means being cooled so that molten polymer in the space between the rolls and the sealing means is solidified; (c) transporting the molten extruded polymer between, into contact with and through the chill rolls, the chill roll surfaces being maintained at a temperature lower than the solidification temperature of the polymer; and (d) transporting the polymer from between the chill rolls to a region of lower pressure.
Claim 3
Dependent Claim
19 words
The process of claim 1 wherein the polymer is a polystyrene and the foaming agent is CO 2 .
Claim 4
Dependent Claim
32 words
The process of claim 1 or claim 2 wherein the polymer is transported from between the rotating chill rolls into an aqueous bath maintained at below the solidification temperature of the polymer."
Claim 5
Dependent Claim
39 words
The process of claim 3 wherein the aqueous bath is a water bath which is in contact with at least the region between the chill rolls so that the polymer issues from between the rolls into the water bath.
Claim 6
Dependent Claim
167 words
Apparatus for producing a polymeric film structure having comparatively high density skin layers and a comparatively low density core layer comprising in combination: (a) extruder means for transporting molten resin containing a foaming agent under pressure from a feed point to a die discharge point; (b) a pair of spaced driven chill rolls in association with and spaced from the die and adapted to receive extruded molten foaming agent-containing polymer therebetween and into contact therewith; (c) chill means for maintaining the chill rolls at a temperature below the molten polymer; and (d) cooled sealing means between the die and the chill rolls, spaced from the chill rolls and occupying a substantial portion of the space between the die and the chill rolls, the rolls and the sealing means being cooled so that molten polymer in the space between the rolls and the sealing means is solidified to at least substantially pressure seal the region between the die and chill rolls and permit a back-pressure to develop therein.
Claim 7
Dependent Claim
167 words
Apparatus for producing a polymeric film structure having comparatively high density skin layers and a comparatively low density core layer comprising in combination: (a) extruder means for transporting molten resin containing a foaming agent under pressure from a feed point to a die discharge point; (b) a pair of spaced driven chill rolls in association with and spaced from the die and adapted to receive extruded molten foaming agent-containing polymer therebetween and into contact therewith; (c) chill means for maintaining the chill rolls at a temperature below the molten polymer; and (d) cooled sealing means between the die and the chill rolls, spaced from the chill rolls and occupying a substantial portion of the space between the die and the chill rolls, the rolls and the sealing means being cooled so that molten polymer in the space between the rolls and the sealing means is solidified to at least substantially pressure seal the region between the die and chill rolls and permit a back-pressure to develop therein.
Claim 8
Dependent Claim
34 words
The apparatus of claim 5 including water bath means for maintaining at least the region between the chill rolls in contact with water at a temperature below the solidification temperature of the extruded polymer.
References Cited (Backward Citations)
No citation records indexed.
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