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US 4,056,587 AGranted
Process for expanding
AssigneeW. R. Grace & Co.
InventorsArvid Honkanen, Paul Joonase
Life of this patent
Estimating the term…
Abstract
Foam styrene polymer sheet is expanded to form foam products having lower density by a process which includes (a) contacting the foam styrene polymer sheet with an aqueous composition, (b) maintaining the aqueous composition in contact with the sheet to effect impregnation of the sheet by the aqueous composition, and thereafter (c) heating the impregnated sheet to expand the sheet. The expanded products are useful as thermal insulation and packaging material.
Claims27
A process for further expanding a previously expanded styrene polymer foam sheet comprising the steps of:
- impregnating the previously expanded styrene polymer foam sheet with an aqueous composition to the extent of at least 0.3 parts of aqueous composition per 100 parts of styrene polymer;
- and
- heating the thus impregnated sheet to at least the softening point of said styrene polymer to soften said polymer and to volatilize said aqueous composition within the porosity of said foam sheet to thus expand said foam sheet by the action of said volatilized aqueous composition to a greater extent than any expansion which would be produced in the absence of said aqueous composition.
Dependencies are inferred from the claim text.