US 5,206,075 A · Sealable polyolefin films containing very low density ethylene copolymers

Abstract

The invention provides laminar polyolefin film materials having a base film layer comprising a blend of an olefin polymer and up to about 30% by weight of at least one very low density copolymer of ethylene and a C.sub.3 to C.sub.20 alpha olefin comonomer copolymerizable with ethylene, said base layer having a heat sealable film layer present on one or both surfaces thereof comprising a very low density copolymer of ethylene and a copolymerizable C.sub.5 to C.sub.12 alpha olefin comonomer. The ethylene copolymer constituents of the film are characterized as having a density in the range of about 0.88 g/cm.sup.3 to abut 0.915 g/cm.sup.3, a melt index in the range of about 0.5 dg/min to about 7.5 dg/min, a molecular weight distribution (M.sub.w /M.sub.n) of about 1.5 to about 3.5 and an essentially single melting point in the range of about 60.degree. C. to about 115.degree. C., measured as a DSC peak T.sub.m. Films of this invention exhibit extremely good hot tack seal strength at temperatures in the range of from about 200.degree. to 290.degree. F. thereby rendering them extremely useful as packaging materials in high speed packaging operations.

Claims15

Dependent claims

A multiple layer heat sealable film comprising a base layer and a heat sealable layer superimposed on one or both sides of said base layer;

said base layer comprising a blend of (a) an olefin polymer having a density in excess of 0.915 g/cm.sup.3 and (b) from about 1 to about 30 weight percent based on base layer polymer content of a copolymer of ethylene and a C.sub.3 to C.sub.20 alpha monoolefin comonomer, said copolymer having a density of from about 0.88 to about 0.915 g/cm.sup.3, a melt index of from about 0.5 to about 7.5 dg/min, a molecular weight distribution of no greater than about 3.5 and a composition distribution breadth index greater than about 70 percent;
said heat sealable layer comprising a copolymer of ethylene and a C.sub.3 to C.sub.20 alpha-monoolefin comonomer, said copolymer having a density of from about 0.88 to about 0.915 g/cm.sup.3, a melt index of from about 0.5 to about 7.5 dg/min, a molecular weight distribution of no greater than about 3.5 and a compositional breath index greater than about 70 percent, said film further characterized in that the ethylene/alpha-monoolefin copolymer present in one of said layers is a copolymer of ethylene and a C.sub.6 to C.sub.10 alpha-monoolefin which alpha-monoolefin differs from the alpha-monoolefin comonomer present in the copolymer of the other said layers.

Dependencies are inferred from the claim text.

Sealable polyolefin films containing very low density ethylene copolymers

Life of this patent

Sealable polyolefin films containing very low density ethylene copolymers

Life of this patent

Abstract

Claims15