The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 02, 1986
Filed:
Mar. 22, 1985
Walter Hufnagel, Forchheim, DE;
Volker Graap, deceased, late of Burk, DE;
Freidrich von und zu Aufsess, Forchheim/Reuth, DE;
Rotger Armsen, Buckenhofen, DE;
Internationale Octrooi Maatschappij 'Octropa' B.V., Rotterdam, NL;
Abstract
An apparatus is disclosed for the fabrication of a biaxially stretched flat film of thermoplastic material, particularly of polypropylene, with improved properties for a process in which the material is first partially pre-stretched 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 pre-stretching are arranged at the inlet section of the biaxial stretching assembly. A system is provided to maintain the fiml exactly at the temperature required by the film characteristics for stretching, and biaxial stretching is done such tht any given point on the film in the region the film is being biaxially streched undergoes simultaneous biaxial stretching both in the longitudinal and transverse direction of the film.