Patent ID: 9180622
Filing Date: 2015-11-10
Classification: B29C

Abstract:
1. A method for the transverse drawing in a sequential biaxial stretching process of a longitudinally oriented film web made from thermoplastic plastic, in which a longitudinally drawn film ( 6 ) is introduced into a transverse drawing frame, wherein the transverse drawing frame includes heater fields ( 1 ), drawing fields ( 2 ) and fixing fields ( 3 ), and the film ( 8 ) is gripped at the beginning of the first heater field on both edges ( 4 ) by the clips ( 7 ) of a clip chain and heated in the heater fields ( 1 ) to a transverse drawing temperature T Q , and the film ( 8 ) is drawn in the subsequent drawing fields ( 2 ) by divergent (V-shaped) guiding of the clip chain in the transverse direction and subjected to a temperature T F in the fixing fields ( 3 ) where T Q >T F , wherein_the boundary zones ( 5 ) of the film ( 8 ) are heated or thermally insulated in the drawing fields ( 2 ) and/or in the fixing fields ( 3 ) in such a way that the boundary zones ( 5 ) of the film ( 8 ) have a higher temperature than the middle of the film web ( 6 ) on transverse drawing and/or fixing ( 4 ).