Shell Oil Comapny

John A Martone

Charles C Hwo

George B Klingensmith

Films of low ether solubles content, satisfactory mechanical properties, and a greatly improved heat seal impact strength can be made from butene-1 polymers which are stereoregular, predominantly isotactic, thermoplastic elastomers (referred to herein as SEPB) and from blends of these polymers with conventional copolymers of butene-1 with small amounts of ethylene (PBE). Because of the low ether solubles content the films are useful for food and medical packaging. Films of low ether solubles content, satisfactory mechanical properties, and excellent heat seal impact strength are produced from SEPB and preferably from blends of SEPB with small amounts of polypropylene and, optionally, high density polyethylene or a crystallization nucleating agent. Mechanical properties of SEPB films are improved by addition of conventional PBE. Conversely, the heat seal impact strength of conventional PBE films is greatly improved and mechanical properties are synergistically improved by addition of minor proportions of SEPB.

Film compositions of butene polymers

The crystallization from the melt of an isotactic butene-1 homopolymer composition, isotactic butene-1-ethylene copolymer or isotactic butene-1-propylene copolymer composition is promoted by adding a small amount of stearamide and high density polyethylene as nucleating agents. The two nucleating agents cooperate in a synergistic fashion, resulting in much faster processing rates.

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Houston, TX, United States of America

John A Martone