The Dow Chemical Company

Michael W Potts

Gerald M Lancaster

Ricky L Tabor

Thomas I Butler

This invention relates to a pinhole-free, pinhole-resistant extrusion composition comprising at least one olefin polymer and to a method of making a pinhole-free, pinhole-resistant coated or laminated substrate. The invention uses either a single polymer composition or a polymer blend wherein the composition has a corrected or actual Goettfert melt strength value in the range of from about 0.01 to about 6.5 centiNetwons to provide a pinhole-free, pinhole-resistant extrusion coating, extrusion lamination, adhesive lamination or in-mold coating or the like. Suitable olefin polymers include high pressure, free-radical initiated ethylene polymers and homogeneously branched ethylene polymers with polymer blends of low density polyethylene and substantially linear ethylene polymers particularly preferred. The coatings, moldings, films or laminations are useful for various substrates including paperboard and can protect against product leakage in such applications as disposable cups for hot beverages.

Pinhole-resistant extrusion method

Multicomponent thermoplastic resin blends are disclosed which have a nonisothermal crystallization half life of less than thirty seconds. Especially preferred are three component resin blends comprising a maleic anhydride grafted HDPE, an unmodified LLDPE copolymer having a density between about 0.905 and 0.93 g/cc, and an unmodified LLDPE copolymer having a density between about 0.89 and 0.92 g/cc. These thermoplastic resin blends can be used as the adhesive layer in multilayer structures. They are especially useful in blown film multilayer structures and they show particularly good adhesion to polar substrates, e.g., EVOH substrates.

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Lake Jackson, TX, United States of America

Michael W Potts