FI891250A0 - POLYPROPEN FILMS AND FARERS FOR FOUNDATION. - Google Patents

Abstract

PURPOSE:To manufacture a film, isotropic and much stronger, by making roll spaces in the given range of a polypropylene film with a given lateral strength or more, guiding the same to two rolls, a low speed and a high speed, having the distance between nip rolls and nip section in a specified range and stretching the film. CONSTITUTION:A polypropylene film with 20 kg/mm<2> or more of strength in the lateral direction is drawn on a drw-off machine 1. A low speed roll 4 and a high speed roll 5 are disposed with 0.05-50mm space A between respective rolls and with 50-500-mm space B between nip rolls 9... and nip sections. A raw polypropylene film is guided from the draw-off machine 1 to a stretching machine 2, and passed on a heated preheating roll 3 and heated thereon while being in the state of mechanical restriction in the lateral direction by the nip rolls 9..., and 1.2-2 times stretching is carried out in the vertical direction of the film by a low speed roll 4 and a high speed roll 5. Said film passes through a heatsetting roll 6, a cooling roll 7, a take-up roll 8 and a thickness meter 10 and wound by a winding machine 11. A polypropylene film, isotropic and much stronger having the tensile strength of 20kg/mm<2> or more and stretching ratio of 100% or less vertically and laterally can easily be manufactured.