Method and apparatus for forming cross-laminated thermoplastic film

Claim 1

A method for forming a continuous cross-laminated, bias-slit web from a supply roll of a layflat, highly machine direction oriented tubular thermoplastic film comprising the steps of: (a) advancing the tubular film over a mandrel in the longitudinal direction of the film while concurrently rotating said supply roll about a rotation axis perpendicular to an axis of said roll, thereby imparting rotation to said film without molecularly orienting it; (b) inflating said tubular film intermediate said supply roll and said mandrel to a pressure preventing collapse of said film; (c) slitting said tubular film downstream of said mandrel at a predetermined bias relative to the movement thereof providing at least two film strips adapted to be superimposed to form said continuous laminated web, said steps (a), (b) and (c) being performed in a manner which does not change the molecular orientation inherent in said tubular film, but which produces in said two strips slit from said tubular film a molecular orientation which has components in both the machine and transverse direction, with the molecular orientation in one of said strips crossing that in the other of said strips; and (d) laminating said two strips together so that the molecular orientation of one crosses the molecular orientation of the other to form a cross-biased laminated film.

Claim 2

A method for forming a continuous cross-laminated, bias-slit web from a supply roll of a layflat, highly machine direction oriented tubular thermoplastic film comprising the steps of: (a) advancing the tubular film over a mandrel in the longitudinal direction of the film while concurrently rotating said supply roll about a rotation axis perpendicular to an axis of said roll, thereby imparting rotation to said film without molecularly orienting it; (b) inflating said tubular film intermediate said supply roll and said mandrel to a pressure preventing collapse of said film; (c) slitting said tubular film downstream of said mandrel at a predetermined bias relative to the movement thereof providing at least two film strips adapted to be superimposed to form said continuous laminated web, said steps (a), (b) and (c) being performed in a manner which does not change the molecular orientation inherent in said tubular film, but which produces in said two strips slit from said tubular film a molecular orientation which has components in both the machine and transverse direction, with the molecular orientation in one of said strips crossing that in the other of said strips; and (d) laminating said two strips together so that the molecular orientation of one crosses the molecular orientation of the other to form a cross-biased laminated film.

Claim 10

An apparatus for forming a continuous cross-laminated, bias-slit web from a supply roll of a layflat, highly machine direction oriented tubular thermoplastic film; comprising a mandrel; means for advancing said tubular film from said supply roll over said mandrel; means for concurrently rotating said supply roll about a rotation axis perpendicular to an axis of said supply roller to impart rotation to said advancing tubular film without molecularly orienting it; means for inflating said tubular film intermediate said supply roll and said mandrel; means downstream of said mandrel for slitting said advancing tubular film at a predetermined bias relative to the film movement to provide at least two film strips adapted to be superimposed to form said continuous laminated web, said advancing means, rotating means and slitting means operating in a manner which does not change the molecular orientation inherent in said tubular film, but which produces in said two strips slit from said tubular film a molecular orientation which has components in both the machine and transverse direction, with the molecular orientation in one of said strips crossing that in the other of said strips; and means for laminating said two strips together so that the molecular orientation of one crosses the molecular orientation of the other to form a cross-biased laminated film.

Claim 11

An apparatus for forming a continuous cross-laminated, bias-slit web from a supply roll of a layflat, highly machine direction oriented tubular thermoplastic film; comprising a mandrel; means for advancing said tubular film from said supply roll over said mandrel; means for concurrently rotating said supply roll about a rotation axis perpendicular to an axis of said supply roller to impart rotation to said advancing tubular film without molecularly orienting it; means for inflating said tubular film intermediate said supply roll and said mandrel; means downstream of said mandrel for slitting said advancing tubular film at a predetermined bias relative to the film movement to provide at least two film strips adapted to be superimposed to form said continuous laminated web, said advancing means, rotating means and slitting means operating in a manner which does not change the molecular orientation inherent in said tubular film, but which produces in said two strips slit from said tubular film a molecular orientation which has components in both the machine and transverse direction, with the molecular orientation in one of said strips crossing that in the other of said strips; and means for laminating said two strips together so that the molecular orientation of one crosses the molecular orientation of the other to form a cross-biased laminated film.