Plastic and nonmetallic article shaping or treating: processes – Forming continuous or indefinite length work – By calendering
Patent
1978-11-27
1981-04-14
Lowe, James B.
Plastic and nonmetallic article shaping or treating: processes
Forming continuous or indefinite length work
By calendering
2642107, 2642358, 2642902, B29D 724
Patent
active
042619440
ABSTRACT:
A method is disclosed for the manufacture of a biaxially stretched polyolefin film, particularly a polypropylene film, having improved properties, in which the material is first partially prestretched in a longitudinal direction and, thereafter, simultaneously biaxially (longitudinally and laterally) stretched, the apparatus comprising stretching rollers for effecting partial longitudinal stretching of the film, the rollers being arranged upstream of an assembly for effecting simultaneous biaxial stretching of the film. The speed of the stretching rollers is infinitely variable so as to influence the total degree of film-stretching only by changing the speed of the rollers. The rollers used for longitudinal prestretching are arranged at the inlet section of the biaxial stretching assembly. A system is provided to maintain the film exactly at the temperature required by the film characteristics for stretching, and biaxial stretching is done such that any given point on the film in the region the film is being biaxially stretched undergoes simultaneous biaxial stretching both in the longitudinal and transverse directions of the film.
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"Biaxial Stretching of Polypropylene Film", by J. Jack, British Plastics, Jul. 1961, pp. 391-394.
Armsen Rotger
Graap, deceased Volker
Hufnagel Walter
von und zu Aufsess Friedrich F.
Lever Brothers Company
Lowe James B.
Sands Philip
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