Maleic anhydride-modified polymer lager coated with polymeric composition derived from vinylidene chloride

DETAILED DESCRIPTION I claim: 1.
A composite consisting of a coated polypropylene film wherein the coating consists of a multipolymer formed from about 80% to about 90% by weight of vinylidene chloride and from about 20% to about 10% by weight of at least one other comonomer; said polypropylene film consisting of a layer formed from a blended mixture of from about 90% to about 99% by weight of isotactic polypropylene and from about 10% to about 1% by weight of a maleic anhydride-modified ethylene, propylene or butene polymer.
2.
A coated polypropylene film in accordance with claim 1 wherein the amount of maleic anhydride-modified ethylene, propylene or butene polymer is from about 2% up to about 5% by weight based upon the weight of the polypropylene resin employed in said polypropylene film.
3.
A coated polypropylene film as defined in claim 1 wherein said comonomer of said coating is selected from the group consisting of vinyl chloride, acrylonitrile methyl acrylate, ethyl acrylate, methyl methacrylate, butylacrylate, 2 ethyl-hexyl acrylate, acrylic acid, methacrylic acid, and Na-2-(methacroyloxy) ethane sulfonate.




Description:
BACKGROUND OF THE INVENTION 1.
Field of the Invention This invention relates to coated polypropylene films having improved heat seal strength, a higher level of coating to film adhesion and greater resistance to the deleterious effects of moisture, i.
e.
, high humidity conditions, upon adhesion.
More particularly, it relates to such polypropylene films comprising polypropylene resins compounded with a minor amount of a maleated polyolefin resin and directly coated with a polyvinylidene chloride coating.
2.
Description of the Prior Art The introduction of oxygen in the form of carbonyl groups on the surface of polyolefin films has been widely used as a means of increasing the wetting and adhesion of coatings.
In most cases, the oxygen concentration is increased by oxidation brought about by flame or corona discharge surface treatment.
This adhesion enhancement is primarily due to the high electronegativity of the bonded oxygen atom and its tendency to promote hydrogen bonds with suitable proton donors present in the coating