W. R. Grace Co.

Anne C Bieler

Milton A Howe, Jr

Henry G Schirmer

A method of improving the high temperature strength of a heat seal which bonds cross-linkable thermoplastic material together by first forming the heat seal and then irradiating the seal area with ionizing radiation to increase the cross-linking in the material of the seal area by at least 2 MR.

Sealing cross-linked thermoplastic materials

The strength of a heat seal which bonds irradiatively cross-linkable thermoplastic materials together can be significantly improved by irradiating the seal area after sealing is completed. This technique is especially effective for improving the seal strength of packaging film laminates such as those having a layer of saran and a layer of ethylene vinyl acetate copolymer.

In the preparation and storage of cooked, bulk packaged food in flexible receptacles, the quality of the food is increased, the cooking conditions are closely controlled, the growth of bacteria is restricted, and the storage time is increased by reducing the interior temperature of the food from its filling temperature of at least 180.degree. F. to below 45.degree. F. in less than a half hour. Said temperature reduction is preferably achieved by filling the receptacle so that the food therein is flowable or mobile and then tumbling the receptacle in a cooling medium so that the food flows or moves within the receptacle. After storage at 28.degree. F. to 32.degree. F., the food may be heated by tumbling the receptacle in a heating medium in order to bring the food quickly to serving temperature thereby avoiding overcooking.

Process for packaging, cooling and storing food items

Sealed cross-linked thermoplastic sheets

An amide/olefin polymeric film laminate suitable for packaging, water cooking, and storing food within the package is prepared by coextruding polyamide and polyolefin layers to form a laminate and then cross-linking the laminate by irradiation. Prior art polyolefin/polyamide laminates delaminate readily when subjected to agitation in hot water, but this tendency is significantly reduced by laminates according to the present invention.

Growing community of inventors

Greenville, SC, United States of America

Anne C Bieler