Breathable and microporous thin thermoplastic film
AssigneeBerry Film Products Company, Inc.
InventorsLeopoldo V. Cancio, Frank Eschenbacher, Jerry Ford
Life of this patent
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Abstract
Breathable, thermoplastic films, laminates, and methods of making films having a basis weight less than or equal to 15 gsm and a water vapor transmission rate of at least about 500 grams H2O/24-hour/m2, wherein the film has a ratio of the MD load at break to the CD load at break of less than about 10, and at least one of a machine direction notched Elmendorf tear strength of at least about 5 g or a machine direction notched trapezoidal tear strength of at least about 15 g, are disclosed.
Claims20
A thermoplastic film made by a method comprising:
- extruding a web comprising a thermoplastic polymer;
- advancing the web onto a chill roller to form a film, the chill roller having a first temperature below the melting point of the thermoplastic polymer;
- advancing the film to a machine direction orientation section comprising at least one heated roller and at least one stretching roller;
- stretching the film in the machine direction orientation section while maintaining the film at a second temperature that produces a film having limited machine direction orientation;
- and
- stretching the film in the cross-direction;
- wherein the thermoplastic film has a ratio of machine direction load at break to a cross-direction load at break of less than about 10, a basis weight of 15 gsm or less, and a breathability of at least 500 grams H2O/24-hour/m2.
A thermoplastic film made by a method comprising:
- advancing a web comprising a thermoplastic polymer and a filler into a nip to form a film, the nip having a first temperature below the melting point of the thermoplastic polymer;
- advancing the film to a machine direction orientation section comprising at least one heated roller and at least one stretching roller;
- stretching the film in the machine direction orientation section while maintaining the film at a second temperature that produces a film having limited machine direction orientation;
- and
- stretching the film in the cross-direction;
- wherein the thermoplastic film has a ratio of machine direction load at break to a cross-direction load at break of less than about 10, a basis weight of 15 gsm or less, and a breathability of at least 500 grams H2O/24-hour/m2.
A thermoplastic film made by a method comprising:
- advancing a film comprising a thermoplastic polymer onto a chill roller having a first temperature which is below the melting point of the thermoplastic polymer, wherein the chill roller forms a nip;
- advancing the film to a machine direction orientation section comprising at least one heated roller and at least one stretching roller;
- stretching the film in the machine direction orientation section while maintaining the film at a second temperature that produces a film having limited machine direction orientation;
- thereby producing a film having a ratio of machine direction load at break to a cross-direction load at break of less than about 10, and a basis weight of from about 5 gsm to about 20 gsm.
Dependencies are inferred from the claim text.