Polyamideimide

Provided is a PAI with which it is possible to obtain a PAI film having both a high elastic modulus and a high elongation when molded into a film shape. The present invention relates to a polyamide-imide (PAI) in which trimellitic anhydride (TMA) and a dimer acid (DA) are used as acid components and o-toluidine diisocyanate (TODI) is used as an isocyanate component, DA is less than 30 mol% with respect to the total number of moles of TMA and DA, and 10-50 mol% of TODI is substituted with diphenyl methane diisocyanate (MDI) and/or toluene diisocyanate (TDI). 本发明提供在成型为膜状时能够得到兼具高弹性模量和高伸长率的PAI膜的PAI。本发明涉及一种聚酰胺酰亚胺(PAI)，使用偏苯三甲酸酐(TMA)和二聚酸(DA)作为酸成分且使用邻联甲苯胺二异氰酸酯(TODI)作为异氰酸酯成分，相对于TMA和DA合计的摩尔数，DA小于30摩尔％，TODI的10～50摩尔％被置换成二苯甲烷二异氰酸酯(MDI)和/或甲苯二异氰酸酯(TDI)。