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Ultra thin heat-shrinkable monolayer polyethylene films

  • US 5,709,932 A
  • Filed: 11/21/1995
  • Issued: 01/20/1998
  • Est. Priority Date: 11/21/1994
  • Status: Expired due to Fees
First Claim
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1. Biaxially oriented heat-shrinkable ultra-thin monolayer film of homogeneous thickness, made of linear low-density polyethylene, made by a flat process in which:

  • at least one ethylene/alpha-olefin copolymer which comprises an alpha-olefin having 4 to 18 carbons and has a density between 0.89 and 0.94 g/cm3 optionally mixed with one or more olefinic polymers is heated above the melt temperature and extruded,the extruded film is poured and cooled at a hardening temperature,the film is drawn a first time in the machine direction between 3 and 7 times the initial dimension of the non-stretched film,the film is drawn a second time in the transverse direction between 3 and 15 times the initial dimension of the non-stretched film,the biaxially oriented film is drawn a third time in the machine direction between 1.01 and 3 times the dimension after the first draw, andthe biaxially oriented film obtained is cooled at room temperature,characterized in that the film has, in at least one direction, a shrink percentage at 120°

    C. above 20%, and in that the film has a thickness between 5 and 11 μ

    m.

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