Biaxially oriented polypropylene film
AssigneeMobil Oil Corporation
InventorsShaw-Chang Chu, Kevin A. Kirk
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Abstract
A thermoplastic film comprising a base layer of a thermoplastic resin which comprises polypropylene and a coating layer of an alkali metal salt of an alkyl sulfate is disclosed. The film is characterized by reduced COF and improved anti-blocking characteristics without the attendant problems associated with decreased clarity, adhesion and wettability common to films treated to improve their COF and anti-blocking characteristics. The disclosure also provides a process for making the film in which the polypropylene-coating thermoplastic resin is extruded into a sheet, said sheet oriented in the longitudinal direction to form a monoxially oriented film, said film coated with the alkali metal salt of an alkyl sulfate and said coated film oriented in the transverse direction.
Claims22
A biaxially oriented polypropylene film comprising
- a longitudinally oriented film comprising polypropylene stretched from about 3 to about 7 times its original length and
- a coating layer of an alkali metal salt of an alkyl sulfate wherein alkyl of the alkyl sulfate contains between about 4 to about 24 carbon atoms,
- wherein said coating layer is provided on a surface of said longitudinally oriented film, prior to transverse orientation of the film, and
- where said coating layer is effective to reduce the coefficient of friction of said surface in the biaxially oriented film, wherein the film, after transverse orientation, is free of optical flaw.
A biaxially oriented polypropylene film comprising
- a longitudinally oriented film comprising polypropylene coextruded with ethylene polypropylene copolymer;
- and
- a coating layer of an alkali metal salt of an alkyl sulfate wherein alkyl of the alkyl sulfate contains between about 4 to about 24 carbon atoms,
- wherein said coating layer is provided on a surface of said longitudinally oriented film, prior to transverse orientation of the film, and
- where said coating layer is effective to reduce the coefficient of friction of said surface in the biaxially oriented film, wherein the film, after transverse orientation is free of optical flaws.
Dependencies are inferred from the claim text.