PURPOSE: To obtain a copolymer as an elastic material having excellent heat resistance, low-temperature properties, oil resistance and flexibility, comprising specified repeating units, and having specified properties.
CONSTITUTION: The copolymer comprises repeating units of the formula (wherein n is 1-20; Z is a residue of a 1-24C aromatic tetracarboxylic dianhydride; and G is a residue of a copolymer of a molecular weight of 500-6000 made from tetramethylene glycol and propylene glycol) and having a weight-average molecular weight (Mw) (in terms of PS) of 1000-500000 and a melt viscosity η(τ, T) as measured at a shear rate τ±40 (s-1) and a temperature T±20 (°C), namely η(0, melting point (Tm) + 20) or 9.46×10-8×Mw3.4 to 1.58×10-13×Mw3.4 and η(6×102, Tm+20) of 1.89×10-8×Mw3.4 to 3.17×10-14×Mw3.4.
YAMAKAWA HIROSHI
KIRIKIHIRA ISAMU
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