Nova Patents
USH1955H

Polyolefin/filler films having increased WVTR and method for making

Claim Score by NHIP

Read claim 6, the broadest

Abstract

Films, made of polyethylenes and fillers, and articles made therefrom greater WVTR than previously available films based on conventional Ziegler-Natta based polyethylenes. The polyethylenes are produced in a metallocene-catalyzed production process. The films may be made by a cast film process, and may be made in widely varying filler content, generally polyethylene to filler ratios of 30/70 to 70/30. The metallocene based polyethylenes when combined with filler also permit the extrusion of thinner films leading to lighter weight and softer films. The m-polyethylenes utilized for making such films typically have a Composition Distribution Breadth Index above 50%, a Mw/Mn below 3, and a Mz/Mw below 2.

Term

Term ended

Projected expiry passed 31 July 2016, 10.1 years ago.

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9 claims: 5 independent, 4 dependent

  1. 1
    A process for making a polyolefin film having high WVTR, comprising:a) mixing at least one polyethylene with a filler in a ratio of 10/80 to 80/20;b) extruding a film from the polyethylene/filler mixture of a);c) stretching the film to a sufficient amount to achieve a WVTR at least 10% higher than the WVTR described by the equation: WVTR=−10,900+320 (filler weight %) wherein said polyethylene has a Mw/Mn less than 3, and a CDBI greater than 50%.
  2. 4
    A polyethylene film having a high WVTR, made by a process comprising:a) combining a polyethylene having Mw/Mn less than 3 with a CaCO 3 , in a weight ratio of from 3:1 to 1:3;b) extruding said combination into a film having a thickness between 2-4 mils;c) stretching said film to a degree sufficient to achieve a WVTR of at least 10% greater than the WVTR described by the equation: WVTR=−10,900+320 (CaCO 3 weight %).
  3. 5
    A method for producing a polyolefin film comprising:a) adding a filler to at least one polyethylene, where said polyethylene has a Mw/Mn of up to 2.5, at a filler to polyethylene ratio of 3:1-1:3;b) forming a film from the polyethylene/filler of a) wherein said film, after stretching in the TD in a ratio from the initial dimension of 2:1-4:1 has a WVTR at least 20% greater than the WVTR described by the equation: WVTR=−10,900+320 (weight % filler).
  4. 6
    Broadest claimClaim Score 86, broad(NHIP)A method of making a filled polyethylene film having a thickness up to 3 mils, comprising:a) forming a film from a polyethylene having a Mw/Mn less than 2.5, combined with CaCO 3 in a ratio polyethylene filler 3:1-1.3, wherein said film has a thickness, as extruded up to 3 mils.
  5. 9
    A polyethylene film having a high WVTR made by a process comprising:a) combining a polyethylene having a Mw/Mn less than 3 and a CDBI greater than 60% with a filler, b) forming a film from the combination of a), c) stretching said film of b) to a sufficient degree to achieve a WVTR of at least 10% greater than the WVTR described by the equation: WVTR =10,900+320 (filler weight %).
Independent claims5