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US 4,067,942 AGranted
Heat treatment of resinous block copolymer to improve clarity
AssigneePhillips Petroleum Company
InventorNewton R. Wilson
Life of this patent
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Abstract
Extruded articles of resinous transparent monovinyl-substituted aromatic compound/conjugated diene block copolymer are subjected to a brief heat treatment which results in a substantial improvement in clarity.
Claims16
A process for producing a transparent extrudate comprising:
- forming a molten extrudate of a resinous transparent monovinyl-substituted aromatic compound/conjugated diene block copolymer having terminal blocks of said monovinyl-substituted aromatic compound, such extrudate being at least about 10 mils thick;
- cooling said extrudate to a solid state;
- and then
- applying heat to a surface of the thus-solidified extrudate for a short time so as to melt only a thin surface layer, thereby increasing clarity without visible distortion of the extrudate.
1 more element
Dependencies are inferred from the claim text.