Solutions of polyamideimides in .gamma.-butyrolactone, process for obtaining them and the yarns thus obtained
AssigneeRhone-Poulenc Fibres
InventorsPhilippe Michaud, Jean Russo
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Abstract
Directly shapeable clear solutions of polyamide imides and a method for preparing same are provided. The solutions are obtained by polycondensation in .gamma.-butyrolactone (.gamma.BL) in substantially stoichiometric proportions between toluylene diisocyanate and an aromatic acid anhydride, and by dilution in (.gamma.BL) to give a solution allowing them to be processed at a later stage. Yarns and fibers made from said solutions are also described.
Claims17
A storable clear solution of polyamideimides which can be directly spun and processed, consisting essentially of:
- a) a polyamideimide in which at least 95% of the repeat units are denoted by the formula --NH--Ar.sub.1 --N(CO).sub.2 Ar.sub.2 --CO-- in which:
- Ar.sub.1 denotes the tolylene divalent aromatic radical,
- Ar.sub.2 denotes a 1,2,4-benzenetriyl trivalent radical, and
- b) as sole solvent, substantially anhydrous gamma-butyrolactone free from butyl alcohol.
A process for obtaining storable clear spinnable solutions of polyamideimides, comprising polycondensing at elevated temperature in substantially stoichiometric proportions:
- tolylene diisocyanate, and
- an aromatic acid anhydride
- in substantially anhydrous .gamma.-butyrolactone (.gamma.-BL) free from butyl alcohol to form a mixture of polyamideimide in the .gamma.-BL, wherein the aromatic acid anhydride is at least 95% trimellitic anhydride, the concentration of polyamideimide in the .gamma.-BL before dilution being at least 27%, diluting with the same solvent the concentration of polyamideimide in the .gamma.-BL at a temperature of at most the polycondensation temperature and cooling the diluted concentration of polyamideimide in the .gamma.-BL to ambient temperature thereby obtaining a clear storable spinnable solution of polyamideimide.
Dependencies are inferred from the claim text.