W. R. Grace Co.

W. R. Grace & Co., Cryovac Div.

W. R. Grace & Co., Cryovac Division

Norman D Bornstein

Henry G Schirmer

Johnnie J Walters

Alan S Weinberg

Timothy T Oberle

Joseph Z Sun

Donald J D'Entremont

A pasteurizable and/or cook-in shrink film is provided that includes a first or sealing layer of a nonlipophillic polymeric material having a softening point greater than that of the following shrink layer; a second or shrink controlling layer, melt bonded to the first layer, of an ethylene homopolymer or copolymer; a third or adhesive layer, melt bonded to the second layer, of a chemically modified polyethylene being irradiatively cross-linkable and having functional groups with a relatively strong affinity for the following barrier layer; a fourth or barrier layer, melt bonded to the third layer, of a hydrolyzed ethylene-vinyl acetate copolymer; a fifth or adhesive layer as in said third layer, melt bonded to the fourth layer; and a sixth or abuse layer, melt bonded to the fifth layer. An associated method for making the film is also provided that includes full coextrusion and selective irradiation and orientation.

Pasteurizable, cook-in shrink film

Disclosed is a multi-layer, heat shrinkable, thermoplastic packaging film which can be heat sealed to itself to provide strong seals at pasteurizing temperatures. The preferred film has four layers including, in order, a sealing surface layer comprising a blend of propylene-ethylene copolymer and (butene-1)-ethylene copolymer, a layer comprising ethylene-vinyl acetate copolymer which may be cross-linked to further increase high temperature strength of the film as desired; a relatively gas impermeable layer comprising a copolymer of vinylidene chloride; and, a surface layer of the same blend as the sealing layer. Receptacles such as end seal and side seal bags can be made from the film at a faster rate than with prior art films and these receptacles have the high temperature seal qualities of propylene polymers and the hot water shrink capabilities of ethylene polymers.

Pasteurizable thermoplastic film and receptacle therefrom

The high temperature strength of a heat seal which bonds irradiatively cross-linkable thermoplastic materials together to form a receptacle can be significantly improved by irradiating the receptacle after the seal has been formed. This technique is especially effective for improving the high temperature seal strength of packaging film laminates such as those having a layer of an olefin homopolymer or copolymer and a layer of hydrolyzed ethylene-vinyl acetate copolymer.

Method of making a thermoplastic receptacle having improved high

Disclosed is a multi-layer, heat shrinkable, thermoplastic packaging film which will produce heat seals having improved strength both in the presence of and absence of grease at elevated temperatures, e.g., at shrink temperatures. The layer providing the sealing surface comprises an ethylene-vinyl acetate copolymer which is more crystalline and about half the thickness of the adjacent layer of less crystalline ethylene-vinyl acetate copolymer. Bags for food products can be made from the film at a faster rate than with prior art films.

Thermoplastic film having improved handling and sealing characteristics

A heat shrinkable multi-layer packaging film having a layer of a hydrolyzed ethylene-vinyl acetate copolymer. Preferably, the film is formed by coextruding the hydrolyzed ethylene-vinyl acetate copolymer layer between two other polymeric layers, at least one of which is cross-linkable, and thereafter irradiating and orienting the multi-layer structure. The resulting film is heat shrinkable and has very low oxygen permeability.

Growing community of inventors

Spartanburg, SC, United States of America

Norman D Bornstein