| 摘要 |
PURPOSE: To obtain an arom. polyimide powder having a low water absorption and improved heat resistance and processibility by grinding a polyimide polymer obtd. by imidizing a specific arom. polyamic acid polymer. CONSTITUTION: A molded item is obtd. by adding a stoichiometric amt. or higher of a dehydrating agent and a catalytic amt. of a tert. amine to a soln. of an arom. polyamic acid polymer represented by formula I (wherein Ar4 and Ar5 are each a divalent org. group; Ar6 is a tetravalent org. group; (s) and (u) are each 1 or higher; and (t) is 0, 1, or higher), forming the soln. into the form of film, thread, or block, and heating the formed soln. at 150 deg.C or lower for 5-90min. The molded item is heated at 150-350 deg.C for 10sec to 5min to give a polyimide polymer represented by formula II (wherein Ar1 and Ar2 are each Ar4 ; Ar3 is Ar6 ; (l)and (n) are each 1 or higher; and (m) is 0, 1, or higher), which is ground to give an arom. polyimide powder having a number average mol.wt. of 50,000 or higher, a glass transition point of 200-350 deg.C, a water absorption (in pure water at 20 deg.C for 24hr) of 0.3-0.5%, and a viscosity of 2-10×10<5> P.
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