| 摘要 |
The present invention relates to solutions of polyamide-imides which can be spun and shaped, and to a process for their preparation. They contain 5 to 30% of a polyamide-imide in a solvent mixture comprising 40-80% by weight of butyrolactone and 20-60% of an aprotic amide solvent. They are obtained by the reaction, in butyrolactone as polycondensation solvent, of a diisocyanate, an aromatic acid anhydride, optionally an alkali or alkaline-earth metal dicarboxybenzenesulfonate, and optionally another aromatic diacid, the concentration of polyamide-imide being from 15 to 36%, followed by dilution in an amide solvent, at a temperature between 120 DEG and 165 DEG C. The solutions obtained are clear at room temperature, are storable, and possess improved color.
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