Process for the production of high molecular weight polyamide-imide resin.
摘要
<p>High molecular weight polyamide-imides having a reduced viscosity of 0.3 dl/g or above and exhibiting excellent heat resistance and melt flowability is produced with good economic efficiency by a process, which process comprises the two reaction stages: (a) a first reaction stage which comprises reacting (I) a trimellitic acid derivative and (II) an aromatic diamine in the presence of a polar solvent in the presence of a first dehydration catalyst until a polyamide-imide resin having a reduced viscosity of 0.2 to 0.5 dl/g as measured at a concentration of 0.5 g/dl in dimethylformamide at 30 DEG C is produced; and (b) a second reaction stage which comprises adding a phosphorous ester as a second dehydration catalyst to the reaction mixture resulting from the first reaction stage and further reacting the reaction mixture until a high molecular weight polyamide-imide resin having a reduced viscosity of 0.3 dl/g or above as measured at a concentration of 0.5 g/dl in dimethylformamide at 30 DEG C is produced. d</p>
