Process for the preparation of semi-ordered polyamide-imides.

摘要

Process for obtaining semiordered polyamideimides.
<??>More particularly, it consists in carrying out the polycondensation in two separate stages:

  1) reaction between a proportion of an aromatic diisocyanate and all of the trimellic anhydride in the presence of dimethylalkyleneurea of pH </= 7 until the intermediate compound is dissolved,
  2) successive addition of one or more aromatic diacids and of the remainder of the aromatic diisocyanate to the dimethylalkyleneurea of pH </= 7 until the polyamideimide obtained is completely dissolved.

<??>The semiordered polymers thus obtained have a Tg lower than the random polymers, and this makes them easier to form.