Method for preparing improved expanded polystyrene sheet
AssigneeArco Polymers, Inc.
InventorsJohn P. Spicuzza, Jr., Joseph M. Sutej
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Abstract
Expanded styrene polymer sheet material is produced by extruding expandable and/or general purpose styrene polymer with a conventional blowing agent, a nucleating system and small amounts of finely divided hydrophilic silicon dioxide and alkaline earth metal oxide. The resulting product has very fine, uniformly sized pores and improved flexibility.
Claims13
In a process for producing microcellular expanded styrene polymer sheet by extruding a mixture containing styrene polymer, a blowing agent and a nucleating system, the improvement comprising extruding with said mixture about 0.002 to 2% of a hydrophilic silica and about 0.002 to 2% of an alkaline earth metal oxide, the percentages of hydrophilic silica and alkaline earth metal oxide being based on the total weight of styrene polymer and said hydrophilic silica and alkaline earth metal oxide being uniformly distributed throughout said mixture whereby said sheet has improved flexibility.
A process of extruding expanded styrene polymer sheet having a small and uniform cell size from styrene polymer feedstock comprising extruding a mixture comprised of the styrene polymer, about 3-10% blowing agent, about 0.01 to 5% nucleating system, about 0.002 to 2% hydrophilic silica having an average particle size of about 1 to 100 millimicrons, and about 0.002 to 2% of an alkaline earth metal oxide selected from the group consisting of magnesium oxide, calcium oxide, barium oxide, and mixtures of these, said percentages being based on the total weight of styrene polymer being extruded.
Dependencies are inferred from the claim text.