FIELD: process engineering.
SUBSTANCE: method and device for lengthwise orientation of thermoplastic film (4) comprise width reduction zone ahead of zone for lengthwise stretching. Film width gradually decreased at passing through the latter to allow lengthwise stretching without necking. Width reduction zone includes at least one pair, preferably, several pairs of grooved rolls (16, 17) provided with engaging grooves or discs for crimping of material. Width reduction zone length is preferably smaller than triple initial width of the film. Width reduction zone incorporates upstream and downstream rolls (14) and (15), respectively, or roll units with bent axles. Note here that there is no special need in conveyor belts for smooth reduction of the width. Lengthwise stretching occurs preferably between aforesaid pairs of rolls, preferably, between more than two pairs of stretching rolls (9-12) arranged relatively close to each other. Folds can originate at several steps their number increasing at every step. Note here that guide means output all folds to, preferably, one side.
EFFECT: higher tensile strength, yield point, resistance to break propagation and to puncture, particularly, for PE and PP films.
39 cl, 11 dwg
