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Multilayer polyolefin substrate with low density core and stiff outer layers

  • US 6,946,203 B1
  • Filed: 12/31/2002
  • Issued: 09/20/2005
  • Est. Priority Date: 12/31/2002
  • Status: Expired due to Fees
First Claim
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1. A thermoplastic structure comprising:

  • a) a low density core layer comprising polypropylene, highly crystalline polypropylene or high density polyethylene, said core layer having a density in the range of from 0.1 to 0.7 grams per cubic centimeters;

    b) a top outer layer comprising highly crystalline polypropylene or high density polyethylene, said top outer layer being exterior to, and on a first side of, said core layer; and

    c) a bottom outer layer comprising highly crystalline polypropylene or high density polyethylene, said bottom outer layer being exterior to, and on a side of, said core layer;

    wherein the thickness of said core layer is about 60 to about 95% of the overall thickness of said structure;

    wherein said structure is biaxially oriented; and

    wherein the stiffness of said structure in the machine direction is in a range from about 0.015 to about 0.15 pound force-centimeters.

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