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US5460890A Biaxially stretched isotropic polyimide film having specific properties 失效
具有特定性质的双轴拉伸各向同性聚酰亚胺膜

Biaxially stretched isotropic polyimide film having specific properties
摘要:
An isotropic, biaxially stretched polyimide film prepared by casting a solution of a polyamic acid precursor in an organic solvent containing a cyclization catalyst and dehydrating agent onto the surface of a support, imidizing the polyamic acid to give a continuous self-supporting gel film containing 5-50% by weight of solids, stretching the gel film in the machine direction (MD) at a ratio of 1.1-1.9, and stretching in the transverse direction (TD) with respect to the machine direction so as to maintain a TD/MD stretch ratio of from 0.9 to 1.3.
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