| 摘要 |
PURPOSE:To obtain a polyamide-imide copolymer which can show good heat stability and flow at 300-400 deg.C and is excellent in the balance of the properties of a molding, by combining specified four structural units. CONSTITUTION:A copolymer comprising structural units A of formula I, structural units B of formula II, structural units C of formula III and structural units D of formula IV in the following ratio. Namely, the ratio of the structural units is such that 1mol of (C+D) is present per mol of (A+B), 0.95-0.05mol of D is present per 0.10-0.95mol of A, and A or B is bonded alternating with C or D. In the formulae, Z is a trifunctional aromatic group in which two of the three functional groups are bonded to adjacent carbons atoms, R1 is a 1-4C alkyl, X is a bond, a group of formula V or the like, Y is a bond, -O- or the like, a is 0 or 1-4, b is 0, 1 or 2, and c is 1-10.
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