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.
Claims11
A blowing agent blend for producing continuously extruded polyolefin foams comprising carbon dioxide present in an amount of from about 1 to less than 20% by weight of the blowing agent, the balance of the blowing agent composition being selected from the group of hydrocarbons consisting of ethane, propane, normal butane, isobutane, and mixtures of any two or more thereof.
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;
- and
- b) extruding the mixture of resin and blowing agent at a rate of from above about 100 kg/m3 to about 500 kg/m3.
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 above about 100 kg/m3 to about 500 kg/m3;
- and
- 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.
An extrudable, expandable composition for producing stable, low density polyolefin foam products, said composition comprising:
- a) a plasticized polyolefin resin;
- b) an aging modifier present in an amount sufficient to control shrinkage of the foam;
- and
- c) a blowing agent for expanding the composition comprising carbon dioxide and a hydrocarbon selected from the group consisting of n-butane, isobutane, propane, and mixtures thereof, said carbon dioxide being present in an amount by weight of from 1 to less than 20% by weight of the blowing agent.
An expandable composition for producing polyethylene foam products, said composition comprising:
- a) a plasticized polyethylene resin;
- b) an aging modifier in an amount of from about 0.5 to 5 kg per 100 kg of resin;
- c) a nucleation agent in an amount of from about 0.05 to 0.5 kg per 100 kg of resin;
- and
- d) a blowing agent in an amount of from about 1 kg to 20 kg per 100 kg of resin for expanding the composition, said blowing agent comprising a blend of about 10% to 15% by weight of carbon dioxide, the balance being a hydrocarbon selected from the group consisting of n-butane, isobutane, propane, and mixtures thereof.
Dependencies are inferred from the claim text.