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AssigneeAsahi Kasei Kogyo Kabushiki Kaisha
InventorsToshinori Shiraki, Susumu Hoshi, Fusakazu Hayano
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A film, sheet, or tube having an excellent low-temperature shrinkage suitable for use as, for example, a heat shrinkable label is disclosed. This film, sheet, or tube contains, as a base polymer, a block copolymer of an aromatic vinyl hydrocarbon polymer block and a polymer block composed mainly of a conjugated diene having the following structure: ______________________________________ (a) (AB).sub.n n = 2-10 (b) A(BA).sub.n n = 2-10 (c) B(AB).sub.n n = 2-10 (d) [(BA).sub.n ].sub.m+2X n = 2-10 and m = 1-10 (e) [(AB).sub.n ].sub.m+2X n = 2-10 and m = 1-10 (f) [(BA).sub.nB].sub.m+2X n = 1-10 and m = 1-10, or (g) [(AB).sub.nA].sub.m+2X n = 1-10 and m = 1-10 ______________________________________ wherein A is an aromatic vinyl hydrocarbon polymer block having a number-average molecular weight of 10,000 through 70,000, B is a polymer block composed mainly of a conjugated diene, and X is a residual group of a coupling agent or a polyfunctional initiator such as an organo polylithium compound, the weight ratio of the aromatic vinyl hydrocarbon to the conjugated diene being 60:40 through 95:5.
An oriented film, sheet, or tube of a block copolymer having an excellent low-temperature shrinkage of not less than 15% in terms of a heat shrinkage factor at 80.degree. C. in at least one direction, comprising, as a base polymer, a block copolymer or any mixture thereof (component (A)), said block copolymer having a melt flow of 0.001 through 70 g/10 min and having the following structure:
Dependencies are inferred from the claim text.