| 摘要 |
A polyimide precursor suitable for use in the pseudo hot-melt prepregging process is described. It consists essentially of a mixture of (a) about 40 to about 70 percent by weight of a substantially equimolar mixture of (i) 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane or 2,2-bis[4-(3-aminophenoxy)phenyl]hexafluoropropane, or both, and (ii) lower alkyl diester of aromatic tetracarboxylic acid; (b) about 2 to about 50 percent by weight of polyamide (polyamic acid or ester) producible from components (i) and (ii); and (c) about 10 to about 50 percent by weight of solvent with the proviso that the mixture is a clear resinous solid at 25 DEG C. and is a viscous, tacky, varnish-like liquid at a temperature falling in the range of 40 DEG C. to 100 DEG C. Also described are use of the polyimide precursors in preparing coated paper webs useful in preparing paper-backed prepregging tape, and use of the coated paper webs in preparing the paper-backed prepregging tapes.
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