Process for the production of oriented films

申请公布号：

GB1143037(A)

申请号：

GB19670043574

申请日期：

1967.09.25

申请公布日期：

1969.02.19

申请人：

W. R. GRACE & CO.

分类号：

B29C47/00;B29C61/00;B29D7/01

主分类号：

B29C47/00

摘要：

1,143,037. Polyethylene films. W. R. GRACE & CO. 20 Sept., 1967 [20 Oct., 1966], No. 43574/67. Heading B5B. A biaxially oriented film of low density polyethylene, which is heat-shrinkable, is made by producing a tubular extrudate of the polymer at a temperature above that at which it becomes 100% non-crystalline (the " final melting temperature"), passing the extrudate through a fluid bath maintained 15-25‹ C. below the final melting temperature for a time not exceeding 5 sec., immediately biaxially orienting the extrudate by internal gas pressure, and finally cooling the extrudate to room temperature. Polyethylene normally has a final melting temperature of 110‹ C., and the fluid bath treatment is suitably for 2-5 sec. in water, ethylene glycol, a silicone oil or a fluidized bed. The product may have a shrink tension (as defined in the Specification) of 190-220 p.s.i.