Lever Brothers Company

Internationale Octrooi Maatschappij 'octropa' Bv

Walter Hufnagel

Rotger Armsen

Volker Graap, Deceased

Friedrich F Von Und Zu Aufsess

Heinz Vates

Wolfgang Hafner

Freidrich Von Und Zu Aufsess

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.

Apparatus for the manufacture of biaxially stretched flat film

A simultaneously biaxially oriented, isotactic polypropylene film resistant to dynamic stresses, particularly tensile stresses in longitudinal direction, which has been stretched in a surface stretch ratio of at least 1:45, exhibiting a specific puncture resistance and certain elongation factors, is particularly suitable as a base or carrier film for acoustical and optical information, for adhesive tape, for multicolor printing, for packaging material and as a layer in laminates.

Polypropylene film

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.

Method for the manufacture of biaxially stretched polyolefin film

Polyvinyl chloride bottles of thin-wall construction are characterized by low oxygen and carbon dioxide permeability and a minimum amount of total additives and, in particular, a low thermal stabilizer content; in addition these bottles have improved tensile and bursting strength, elasticity, and drop resistance making them most suitable for containing oxygen sensitive and carbonated beverages. The bottles are made by forming a preform, comprising at least 70% vinyl chloride polymer material, at a temperature within the thermoplastic temperature range of the material, adjusting the temperature of the preform to within its thermoelastic range from 90.degree.C. to 140.degree.C., and biaxially stretching the preform by rapidly blow molding it to the dimensions of the mold achieving rates of stretch between about 100% and 1000% and above per second. Best orientation is obtained when the preform is stretched within 3 seconds and at a temperature in the thermoelastic range where the stretching capacity of the preform exceeds about 225%.

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Forchheim, Germany

Walter Hufnagel