Process for stretching incremental portions of an orientable thermoplastic substrate and product thereof
AssigneeBiax-Fiberfilm Corporation
InventorEckhard C. A. Schwarz
Life of this patent
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Abstract
There is disclosed a novel process and product produced thereby for the selective stretching of incremental portions of a substrate of a synthetic thermoplastic material selected from the group consisting of a thermoplastic orientable polymer or a blend of a thermoplastic orientable copolymer in which there is admixed an incompatible second phase selected the group consisting of an incompatible polymer or inorganic material. The substrate is stretched in grooved roller pairs by controlling the velocity of introduction of the substrate to maintain the velocity substantially identical to the surface velocity of the roller pair. Stretching of the blends produce an opaque, low density porous sheet.
Claims16
A process for longitudinally stretching incremental portions of a film of synthetic thermoplastic material selected from the group consisting of a thermoplastic orientable polymer or a blend of thermoplastic orientable polymers in which there is admixed an incompatible second phase material selected from the group consisting of an incompatible polymer or inorganic material which comprises:
- (a) introducing said film into a nip of interdigitating rollers having grooves substantially parallel to the axis of said rollers;
- (b) controlling the velocity of introduction of said film into said nip to assume and maintain the velocity substantially identical to the surface velocity of said rollers to prevent slipping of said film and thereby longitudinally stretch incremental portions of said film by a deflection of said film into the shape of said grooves;
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- (c) collecting the thus formed sheet.
A process for bi-axially stretching incremental portions of a film formed of synthetic thermoplastic material selected from the group consisting of a thermoplastic orientable polymer or a blend of thermoplastic orientable polymers in which there is admixed an incompatible second phase material selected from the group consisting of an incompatible polymer or inorganic material which comprises:
- (a) introducing said film into a nip of interdigitating rollers having grooves parallel to the axis of said rollers;
- (b) controlling the velocity of introduction of said film into said nip to assume and maintain the velocity substantially identical to the surface velocity of said rollers to prevent slipping of said film and thereby longitudinally stretch incremental portions of said film by deflection of said film into the shape of said grooves;
- (c) withdrawing said film from said rollers at a velocity greater than the rotational velocity of said rollers;
- (d) introducing said film into a nip of interdigitating rollers having grooves substantially perpendicular to the axis of said rollers;
- (e) controlling the velocity of introduction of said web into said nip to assume and maintain the velocity substantially identical to the surface velocity of said rollers to prevent narrowing of said film prior to introduction into said nip thereby to laterally stretch incremental portions of said web by deflection of said film into shape of said grooves;
- (f) withdrawing said web from said rollers at a velocity substantially corresponding to the velocity of introduction and;
- (g) collecting the thus stretched film.
A process for stretching incremental portions of a film formed of synthetic thermoplastic material selected from the group consisting of a thermoplastic orientable polymer or a blend of thermoplastic orientable polymers in which there is admixed an incompatible second phase material selected from the group consisting of an incompatible polymer or inorganic material which comprises:
- (a) introducing said film into a nip of interdigitating rollers having grooves substantially perpendicular to the axis of said rollers;
- (b) controlling the velocity of introduction of said film into said nip to assume and maintain the velocity substantially identical to the surface velocity of said rollers to prevent narrowing of said film prior to introduction into said nip thereby to laterally stretch incremental portions of said film by deflection of said film into the shape of said grooves;
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- (c) collecting the thus laterally stretched film.
Dependencies are inferred from the claim text.