Nestable foam cup with improved heat retention and the process for its manufacture
AssigneeMobil Oil Corporation
InventorsDonald W. Myers, Samantha L. Vivlamore
Life of this patent
Estimating the term…
Abstract
A thermoformed polymeric foam article, such as a cup or container, is disclosed having improved thermal insulation properties. Contact with hot water causes expansion of the foam wall, substantially decreasing foam density and providing greater heat retention.
Claims17
A thermoplastic foam container consisting essentially of oriented styrenic polymer having a deep drawn wall of polymer foam, said foam characterized by containing flat, elongated, pancake-shaped, interleaved, gas-containing cells, uniformly distributed generally parallel to the codirectional wall surfaces;
- said styrenic polymer having a Vicat softening point of at least 100.degree. C.;
- said wall further characterized by having an average specific gravity of less than 0.15 prior to any thermally caused increase in wall thickness;
- and said container capable of undergoing an excess of 10% increase in wall thickness when subjected to a temperature between about 82.degree. C. and about 100.degree. C.
A nestable thermofoamed styrenic polymer foam cup comprising a thermally-expandable foam which expands in thickness at least 10% upon contact with hot fluid at between about 82.degree. C. to about 100.degree. C. for a predetermined dwell time to provide improved heat retention;
- the foam structure comprising flat, elongated, pancake-shaped, interleaved, gas-containing cells, uniformly distributed generally parallel to the codirectional wall surfaces of the cup wall.
In a thermoformed polymeric foam article with substantially uniform wall thickness comprising linear styrenic polymer having a thermal expansion capacity, the improvement which comprises:
- a cellular foam wall comprising a polymeric matrix and closed gas cells dispersed therein, the cells of the cellular foam wall comprising flat, elongated, pancake-shaped, interleaved, gas-containing cells, uniformly distributed generally parallel to the codirectional wall surfaces of the article wall;
- and
- the polymeric matrix having significant stretch orientation.
A method for obtaining improved heat retention in hot cup-containers comprising the steps of:
- providing a thermoplastic foam container consisting essentially of oriented styrenic polymer having a deep drawn wall of low-density polymer foam containing flat, elongated, gas-containing cells, uniformly distributed through the wall, said styrenic polymer having a Vicat softening point greater than 100.degree. C., wherein said container prior to thermal deformation has an average density of less than 0.15 grams/cc;
- contacting the container with fluid at a temperature in the range of about 82.degree. C. to 100.degree. C.;
- and
- permitting a wall growth in excess of 10% of thickness.
Dependencies are inferred from the claim text.