High-strength laminate
First Claim
1. A high-strength generally continuous flexible laminate comprised of at least two generally continuous films each being biaxially oriented and generally weakly adhered to an adjacent such film in face-to-face relation, each such film being formed by extrusion with coincidental melt attenuation of a blend of at least two polymers which are sufficiently incompatible as to exhibit upon said extrusion an internal microscopic fibrillar morphology in which elongated fibrils are arranged in a generalized grain-like pattern having one predominant grain direction and imparting a corresponding direction of splittability to such film, such generalized grain pattern including fibrils having microscopically visible recurrent deflections from said predominant grain direction at intervals therealong which form a substantially zig-zagging specific grain configuration incorporated within said generalized grain pattern, the films being arranged in the laminate in such manner that the respective directions of splittability for at least two such films intersect each other.
0 Assignments
0 Petitions
Accused Products
Abstract
A high-strength laminate comprising generally weakly adhered biaxially oriented films, each formed of a blend which exhibits a distinct fibrous morphology with the fibres forming a distinct unidirectional grain when measured in a micro-scale but with the fibre-portions strongly deflected from this direction as seen on a micro-scale, the films being arranged in the laminate such that the undirectional grain in at least two of the films criss-cross each other. This laminate is produced by melt attenuating the blend(s) while extruding the latter into film-like layers, cross-laminating at least two layers before or after solidification while they are still in molecularly unoriented state--except for the weak orientation produced by the melt-attenuation--and finally strongly biaxially orienting the laminate by stretching in several steps, whereby the stretching is generally uniaxial during each step.
-
Citations
18 Claims
- 1. A high-strength generally continuous flexible laminate comprised of at least two generally continuous films each being biaxially oriented and generally weakly adhered to an adjacent such film in face-to-face relation, each such film being formed by extrusion with coincidental melt attenuation of a blend of at least two polymers which are sufficiently incompatible as to exhibit upon said extrusion an internal microscopic fibrillar morphology in which elongated fibrils are arranged in a generalized grain-like pattern having one predominant grain direction and imparting a corresponding direction of splittability to such film, such generalized grain pattern including fibrils having microscopically visible recurrent deflections from said predominant grain direction at intervals therealong which form a substantially zig-zagging specific grain configuration incorporated within said generalized grain pattern, the films being arranged in the laminate in such manner that the respective directions of splittability for at least two such films intersect each other.
Specification