| 摘要 |
PROBLEM TO BE SOLVED: To provide a manufacturing method of a polyamic acid solution dissolving the polyamic acid in a solvent which can obtain a polyimide having various mechanical properties, for example, high tensile strength at break and high extension degree, and which has a high polymerization degree and controls branching generation. SOLUTION: A manufacturing method of a polyamic acid comprises a reaction in which, making a suspension to suspend a compound having not more than 300 ppm of a water content and two or more acid anhydride groups per molecule in a solvent, into this suspension a compound having two or more amino groups per molecule is dropped with 10-100 equivalent % per hour and a temperature of the reaction system is maintained at 50 deg.C or below.
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