Method and composition for making foamed polyethylene material
AssigneeFree-Flow Packaging International, Inc.
InventorsWilliam D. McIntyre, Roderick R. Alire, Ronald N. Clazie
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Abstract
Method and composition for making an expanded polyethylene material by forming a foamable melt of polyethylene, a nucleating agent, a material which retards migration of alkanes, and a blowing agent which comprises 10 to 100 mole percent ethane. In one disclosed embodiment, the melt is passed through an annular extrusion die to form an elongated tube of extruded material which is then expanded, slit lengthwise and laid flat to form a sheet of the expanded material.
Claims16
In a method of making a foamed polyethylene sheet, the steps of:
- (a) forming a foamable melt consisting essentially of low density polyethylene, a nucleating agent in the amount of up to 200 grams of nucleating agent per 800 pounds of polyethylene, glycerol monostearate in an amount of about one to four percent by weight of the polyethylene, and a blowing agent consisting of about 50 to 95 mole percent ethane, and 5 to 50 mole percent isobutane,
- (b) passing the melt through an annular extrusion die to form an elongated tube of extruded material
- (c) expanding the extruded material, and
- (d) slitting the tube in a lengthwise direction and unrolling the material to form a sheet of the expanded material.
In a method of making a foamed polymer material, the steps of:
- (a) heating a polymer selected from the group consisting of polyethylene, polyethylene copolymers, ionomers, and combinations thereof,
- (b) forming a foamable melt by introducing into the heated polymer a blowing agent consisting of about 50 to 95 mole percent ethane, and 5 to 50 mole percent isobutane,
- (b) passing the melt through an extrusion die, and
- (c) expanding the extruded material.
In a method of making a foamed polymer material, the steps of:
- (a) heating a polymer selected from the group consisting of polyethylene, polyethylene copolymers, ionomers, and combinations thereof, and
- (b) introducing into the heated polymer a blowing agent consisting of ethane and isobutane, the ethane being present in the blowing agent in an amount of at least about 40 percent by weight based upon the total weight of the blowing agent.
In a method of making a foamed polymer material, the steps of:
- (a) heating a polymer selected from the group consisting of polyethylene, polyethylene copolymers, ionomers, and combinations thereof,
- (b) forming a foamable melt by introducing into the heated polymer a blowing agent consisting of about 50 to 95 mole percent ethane, and 5 to 50 mole percent isobutane, and
- (c) expanding the foamable melt.
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, the blowing agent consisting of ethane and a different alkane selected from the group consisting of C3 and C4 alkanes, the ethane being present in said resin in an amount of at least about 40 percent by weight based upon the total weight of the blowing agent;
- and
- (b) extruding the mixture of resin and blowing agent so as to produce a low density foamed polyolefin product.
Dependencies are inferred from the claim text.