| 摘要 |
<p>Process for the manufacture of an enamelling varnish based on polyamide-imide, in which an aromatic diisocyanate or a corresponding diamine is condensed with an aromatic polycarboxylic acid containing at least three carboxyl functional groups, or an anhydride, ester or halide of corresponding acid, in solution in an aprotic polar reaction solvent at least partially other than N-methylpyrrolidone, then a dilution solvent is added to the reaction solution, characterised in that the weight content of N-methylpyrrolidone in the aprotic polar reaction solvent does not exceed 30 % and in that, after dilution, the weight content of N-methylpyrrolidone in the varnish solvent is adjusted between 20 % and 30 %. Varnish manufactured by this process, stable to storage and exhibiting a reduced viscosity which makes enamelling easier.</p> |
