Polyolefin-based wrapping film
AssigneeMitsubishi Petrochemical Co., Ltd.
InventorsTakao Yazaki, Masataka Noro, Takashi Matsui, Noriyuki Kobayashi, Hironari Sano, Koji Yamamoto
Life of this patent
Estimating the term…
Abstract
A polyolefin-based wrapping film having one or more layers which satisfies the following conditions (1) to (4): (1) the film has a thickness ranging from 6 to 100 .mu.m; (2) the film has a birefringence .DELTA.n.sub.A of from 0.6.times.10.sup.-3 to 8.times.10.sup.-3 ; (3) the film has a ratio of percent heat shrinkage in MD to percent heat shrinkage in TD of from 0.65 to 1.50 in a silicon oil bath at 140.degree. C. for 3 minutes; and (4) the film has a strain recovery of at least 18 mm, which provides excellent performance properties in stretch wrapping, especially in the area of high deformation recover.
Claims30
A wrapping film of a polyolefin-based resin, wherein the film has the following properties:
- (1) a thickness ranging from 6 to 100 .mu.m;
- (2) a birefringence .DELTA.n.sub.A ranging from 0.6.times.10.sup.-3 to 8.times.10.sup.-3, said birefringence defined by equation:
- .DELTA.n.sub.A =.vertline.n.sub.MD -n.sub.TD .vertline.
- wherein n.sub.MD is a refractive index in the machine direction, and n.sub.TD is a refractive index in the transverse direction;
- (3) a ratio S.sub.MD /S.sub.TD ranging from 0.65 to 1.50, wherein S.sub.MD and S.sub.TD are each heat shrinkage in the machine direction and that in the transverse direction when the film is allowed to stand in a silicone oil bath at 140.degree. C. for 3 minutes;
- and
- (4) a strain recovery of 18 mm or more, as determined by clamping a circular film specimen having a diameter of 100 mm, indenting at the center thereof with a hemispherical indenter 20 mm in diameter to cause deformation, and measuring the maximum strain which disappears completely upon removal of the indenter.
Dependencies are inferred from the claim text.