Thermoformed plastic containers with transparent windows and method of making same
AssigneeEastman Kodak Company
InventorsScott B. Hardenbrook, Cynthia L. Desmond
Life of this patent
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Abstract
A container component is made from microcellular foam material, no more than approximately 30 mils thick, having a core of very small uniformity distributed cells to provide uniform opacity that is locally eliminated by the application of heat and pressure to create window areas at least 60% as thick as the surrounding material.
Claims10
A container component made from substantially opaque microcellular foamed sheet plastic material, said component including a transparent window formed by heating and compressing the corresponding region of said material to eliminate foam in that region, said window being at least 60% as thick as said material in its foamed condition.
The method of producing a transparent window in a component made from microcellular foamed sheet plastic material by compressing a region of said material corresponding to said window between confronting smooth surfaces of a mold and a die, said method comprising the steps of:
- (a) heating the material to a surface temperature in the range of approximately 275.degree.-300.degree. F.
- (b) maintaining the die at a temperature in the range of approximately 85.degree.-250.degree. F.;
- (c) maintaining the mold at a temperature in the range of approximately 150.degree.-180.degree. F.;
- and
- (d) urging said die toward said mold with a pressure of at least 2000 pounds per square inch of window area.
Dependencies are inferred from the claim text.