Method of preparing a cross-linked, polyethylene foam product by surface expansion of a foam
AssigneeEarth & Ocean Sports, Inc.
InventorsJohn D. Bambara, Jon A. Glydon
Life of this patent
Estimating the term…
Abstract
A method for the preparation of a cross-linked, rigid, polyethylene, foam sheet product, which method comprises heating at least one surface of a cross-linked, polyethylene, foam sheet material, to a temperature sufficient to cause a slight surface post-expansion of the foam sheet material, contacting the heated, post-expanded, foam surface with a cold metal element, to form a cross-linked, polyethylene, foam sheet product of the desired, accurate thickness, or having a desired three-dimensional design on the cross-linked, foam sheet material.
Claims11
A method for the preparation of a controlled thickness, crosslinked, thermoplastic, foam sheet product, which method comprises:
- a) providing a pre-formed cross-linked, rigid, thermoplastic, olefinic, foam sheet material of varied thickness, cross-linked in an amount greater than about ten percent and containing residual blowing agents therein, the foam sheet material capable of further surface expansion;
- b) surface heating only at least one surface of the rigid, cross-linked, thermoplastic, foam sheet material to a temperature greater than about 250.degree. F. and sufficient to cause slight surface foam expansion of the foam surface of the foam sheet material, said surface foam expansion being not greater than about 1/4 inch;
- c) contacting the heated, post-expanded foam surface of the cross-linked foam sheet material with a cold element to form a foam sheet material of desired, controlled thickness dimensions with a thin, densified skin layer;
- and
- d) recovering the controlled thickness dimension foam sheet product.
The method of claim 8 which includes cutting out the embossed design from the foam sheet material and recovering the embossed foam sheet product.
A method for the preparation of an accurately dimensioned, cross-linked, polyethylene, rigid foam sheet material adapted for use in the production of body boards and surf boards, which method comprises:
- a) providing a preformed, cross-linked, rigid, polyethylene foam sheet material of varied thickness containing residual blowing agents therein, the sheet material capable of further expansion and cross-linked in the amount of about 40% to 90% and having a foam density of about 4 to 16 pounds per cubic foot;
- b) heating both surfaces of the foam sheet material to a temperature of about 250.degree. F. to 450.degree. F. by the impingement onto the surface of hot air or infrared heat to cause a slight surface foam expansion of the foam sheet material, said surface foam expansion being not greater than about 1/4 inch.
- c) passing the surface-heated foam sheet material through a pair of spaced apart, cold rollers having a temperature of less than about 100.degree. F. to form a foam sheet material of desired, controlled thickness with a thin, densified, polyethylene skin layer on both surfaces;
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- d) recovering the controlled thickness foam sheet material.
Dependencies are inferred from the claim text.