Patent ID: 6461696
Filing Date: 2002-10-08
Classification: B29C,B32B,C08L,Y10T

Abstract:
A multiple layer thermoplastic structure:(1) a skin layer selected from the group consisting of polypropylene, ethylene homopolymers having a density of from about 0.930 g/cc to about 0.960 g/cc, and ethylene homopolymers having a density of from about 0.930 g/cc to about 0.960 g/cc blended with an ethylene and &agr;-olefin copolymer having a density less than about 0.930 g/cc, the skin layer having a thickness of greater than about 3.0 mils; (2) a radio frequency susceptible layer adhered to the skin layer, the radio frequency susceptible layer having a dielectric loss greater than 0.05 at 1-60 MHz and at temperatures of ambient to 250Â° C., the radio frequency susceptible layer having: (a) a first polyolefin selected from the group consisting of polypropylene and polypropylene copolymers, (b) a second polyolefin selected from the group consisting of ethylene copolymers, ultra-low density polyethylene, polybutene, and butene ethylene copolymers; (c) a radio frequency susceptible polymer selected from the group consisting of (i) ethylene copolymers having 50-85% ethylene content with comonomers selected from a first group consisting of acrylic acid, methacrylic acid, ester derivatives of acrylic acid with alcohols having 1-10 carbons, ester derivatives of methacrylic acid with alcohols having 1-10 carbons, vinyl acetate, and vinyl alcohol (ii) homopolymers and copolymers containing at least one segment of urethanes, esters, ureas, imides, sulfones, and amides, and (d) a compatibilizing agent of a styrene and hydrocarbon copolymer; wherein the structure when fabricated into a 50 ml container has a water vapor transmission rate of less than 8% by weight after the container has been autoclaved at 121Â° C. for 20 minutes and stored for 90 days in an environmentally regulated compartment having 15% relative humidity at 40Â° C.