Severable multilayer thermoplastic film
AssigneeMinnesota Mining and Manufacturing Company
InventorsRalph H. Bland, William A. Peper, Bruce D. Stambaugh
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Abstract
A dispensable multilayer film having alternating layers of a ductile material, a brittle material, and optionally an intermediate layer. The film has excellent strength in its longitudinal and transverse directions but can be transversely cut by forces of less than 9 Newtons on the cutters of commercially available table top tape dispensers. At least one surface of the sheet material can be coated with a functional material.
Claims45
A thermoplastic, severable film having a plurality of randomly occurring parallel layers of a brittle thermoplastic polymeric material having a glass transition temperature of greater than 50.degree. C., and a ductile polymeric material having at least 100% elongation at break situated one on the other in an array, said array comprising the product of a steam of each of said materials which, independently, has been split into a predetermined number of substream and said substreams subsequently recombined to form said array,
- wherein no two adjacent layers of said array are of the same material, and
- wherein each of said layers has sufficient adhesion to said adjacent layers to enable said film to be severed precisely in a straight line.
A severable thermoplastic film having a stretch at dispensing of no more than 6.5% said film comprising at least five layers situated one on the other in a parallel array, said layers occurring essentially randomly in said array and being individually selected from a brittle thermoplastic polymeric material having a glass transition temperature of greater than 50.degree. C., and a ductile polymeric material having at least 100% elongation at break, wherein no two adjacent layers are of the same material, and
- wherein each of said layers has sufficient adhesion to said adjacent layers to enable said film to be severed precisely in a straight line.
A severable film having at least five alternating, parallel layers of dissimilar materials, wherein no two adjacent layers are of the same material, and wherein each layer comprises either a brittle thermoplastic polymeric material having a glass transition temperature of greater than 50.degree. C., or a ductile polymeric material having at least 100% elongation at break, and wherein said film has a stretch at dispensing of no more than 6.5%, and
- wherein each of said layers has sufficient adhesion to said adjacent layers to enable said film to be severed precisely in a straight line.
A severable film having at least five layers comprising randomly occurring layers of a brittle thermoplastic polymeric material having a glass transition temperature of greater than 50.degree. C., a ductile polymeric material having at least 100% elongation at break and optionally an intermediate material which enhances the adhesion between the brittle and ductile materials, wherein no two adjacent layers are of the same material, said film stretching by no more than 6.5% when wherein each of said layers has sufficient adhesion to said adjacent layers to enable said film to be severed precisely in a straight line.
A severable film having a plurality of randomly occurring parallel layers of a brittle thermoplastic polymeric material having a glass transition temperature of greater than 50.degree. C., and a ductile polymeric material having at least 100% elongation at break situated one on the other in an array, wherein one of said materials forms an envelope around said array.
A method of making a severable, thermoplastic film containing alternating layers of a ductile polymeric material having at least 100% elongation at break, a brittle thermoplastic polymeric material having a glass transition temperature of greater than 50.degree. C., and, optionally, an intermediate material capable of enhancing the adhesion between the brittle and ductile materials comprising the steps of
- providing an individual stream of each material in a flowable state,
- separating each said individual stream into substreams of said materials in said flowable state, the number of substreams being individually predetermined for each stream,
- combining said substreams to form an array of randomly occurring parallel layers of said materials in intimate contact with adjacent layers of said materials, wherein the outermost of said materials forms an envelope around said film, and
- cooling said film to a non-flowable state.
Dependencies are inferred from the claim text.