Expandable composition, blowing agent, and process for extruded thermoplastic foams
AssigneeSealed Air Corporation (US)
InventorsShau-Tarng Lee, Natarajan S. Ramesh, James Baker
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Abstract
An extruded thin sheet foam is disclosed prepared from a polyolefin resin in which the blowing agent comprises a blend of from about 1 to 25% by weight of carbon dioxide and the balance of C3 to C4 VOCs. Thin foam sheets produced with the blowing agent age about twice as fast as foams prepared with VOCs, are remarkably stable, and can be produced at high throughputs.
Claims21
A process for producing an extruded, low density polyolefin foam product, said process comprising the steps of:
- a) mixing a blowing agent with a plasticized polyolefin resin including a fatty ester based aging modifier, the blowing agent comprising a blend of carbon dioxide and a hydrocarbon selected from among the group consisting of ethane, n-butane, isobutane, propane, and mixtures thereof, wherein said carbon dioxide is present in an amount of from about 1 to 25% by weight of the blowing agent;
- b) extruding the mixture of resin and blowing agent at a rate of from about 150 kg/hr to 500 kg/hr;
- and
- c) expanding the mixture so as to produce a dimensionally stable foam sheet product of thickness less than 0.5 inches.
A process for producing an expanded polyethylene foam product, said process comprising the steps of:
- a) mixing a blowing agent comprising from about 1 to 20% by weight of carbon dioxide and the balance a hydrocarbon selected from among the group consisting of ethane, n-butane, isobutane, propane, and mixtures thereof with a plasticized polyethylene resin, an aging modifier, and a nucleation agent in the melting zone of an extruder;
- b) extruding the mixture of blowing agent and resin through the orifice of the extruder agent at a rate of from about 150 kg/hr to 500 kg/hr;
- and
- c) expanding the mixture so as to produce a dimensionally stable foam sheet product of thickness less than 0.200 inches and density of from 10 to 60 kg/m3.
A process for producing an extruded, low density polyolefin foam product, said process comprising the steps of:
- a) mixing a blowing agent with a plasticized polyolefin resin including a fatty ester based aging modifier, the blowing agent comprising a blend of carbon dioxide and a hydrocarbon selected from among the group consisting of ethane, n-butane, isobutane, propane, and mixtures thereof, wherein said carbon dioxide is present in an amount of from about 1 to 25% by weight of the blowing agent;
- b) extruding the mixture of resin and blowing agent at a rate of from about 150 kg/hr kg/hr to about 500 kg/hr;
- c) expanding the mixture so as to produce a dimensionally stable foam sheet product of thickness less than 0.5 inches;
- and
- d) aging the foam to reduce the concentration of blowing agent in the foam to less than 50 percent of the lowest explosive limit within three days.
A process for producing an extruded, low density polyolefin foam product, said process comprising the steps of:
- a) mixing a blowing agent wit a plasticized polyolefin resin including a fatty ester based aging modifier, the blowing agent comprising a blend of carbon dioxide and a hydrocarbon selected from among the group consisting of ethane, n-butane, isobutane, propane, and mixtures thereof, wherein said carbon dioxide is present in an amount of from about 1 to 25% by weight of the blowing agent;
- b) extruding the mixture of resin and blowing agent at a rate of from about 150 kg/hr to about 500 kg/hr;
- c) expanding the mixture so as to produce a dimensionally stable foam sheet product of thickness less than 0.5 inches;
- and
- d) aging the foam to reduce the concentration of blowing agent in the foam to less than 80 percent of the lowest explosive limit within three days.
Dependencies are inferred from the claim text.