Purification, impregnation and foaming of polymer particles with carbon dioxide
AssigneeArco Chemical Technology, L.P.
InventorsBernard H. Meyer, Joseph C. Kinslow
Life of this patent
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Abstract
A process for making high-purity foam moldings without the use of organic blowing agents involves the use of inorganic gases such as carbon dioxide, nitrogen, air and other pneumatogens. The process involves the simultaneous impregnation and purification of the polymers with or without foaming. If foaming is not done in the extractor, the polymeric particles can be foamed in pre-expanders or expanded and molded in downstream equipment.
Claims15
A process for foaming polymers and copolymers, comprising the steps of
- (a) placing the desired polymer or copolymer particles in a pressure vessel extractor-impregnator;
- (b) continuously extracting the polymer particles with a fluid at liquid or supercritical conditions to remove low molecular weight compounds while impregnating the polymer particles with the extracting fluid;
- (c) separating the purified, impregnated polymer particles from the extractor-impregnator;
- (d) pre-expanding the purified, impregnated particles at a temperature above the glass transition temperature of the polymer-fluid blend;
- and
- (e) molding the expanded particles by heating in a foam molding machine.
A process for foaming polymers and copolymers, comprising the steps of
- (a) placing the desired polymer or copolymer particles in a pressure vessel extractor-impregnator;
- (b) continuously extracting the polymer particles with carbon dioxide at liquid or supercritical conditions to remove low molecular weight compounds while impregnating the polymer particles with the carbon dioxide, wherein the mixture of carbon dioxide and low molecular weight compounds is continuously removed from the extractor-impregnator to a recovery chamber wherein the mixture is vented to a condenser to separate the carbon dioxide from the low molecular weight compounds, and wherein the resulting purified carbon dioxide is then continuously returned to the extractor-impregnator;
- (c) separating the purified, impregnated polymer particles from the extractor-impregnator;
- (d) pre-expanding the purified, impregnated particles at a temperature above the glass transition temperature of the polymer-carbon dioxide blend;
- (e) reimpregnating the expanded particles in gas, liquid, or solid carbon dioxide, air, nitrogen, or other pneumatogens, and
- (f) molding said reimpregnated expanded particles by heating in a foam molding machine.
A process for making foamed, molded polystyrene, comprising the steps of:
- (a) placing expandable polystyrene beads in a pressure vessel extractor-impregnator;
- (b) continuously extracting the beads with carbon dioxide at supercritical conditions to remove low molecular weight compounds while impregnating the beads with carbon dioxide, wherein the mixture of carbon dioxide and low molecular weight compounds is continuously removed from the extractor-impregnator to a recovery chamber wherein the mixture is vented to a condenser to separate the carbon dioxide from the low molecular weight compounds, and wherein the resulting purified carbon dioxide is then continuously returned to the extractor-impregnator;
- (c) separating the purified;
- impregnated polystyrene beads from the extractor-impregnator;
- (d) pre-expanding the beads at a temperature above the glass transition temperature of the polystyrene-carbon dioxide blend;
- (e) reimpregnating the expanded beads in gaseous, liquid, or solid carbon dioxide, air, nitrogen, or other pneumatogens;
- and
- (f) molding said reimpregnated, expanded beads by heating in a foam molding machine.
Dependencies are inferred from the claim text.