| 摘要 |
PROBLEM TO BE SOLVED: To provide an aromatic polyimide which is excellent in the heat resistance and besides reconciles the low elasticity and the low thermal expansion coefficient and to provide an aromatic polyamide acid which is a precursor thereof. SOLUTION: The aromatic polyamide acid has 10% by mole or more of a constitutional unit expressed by general formula (1) (wherein, Ar<SB>1</SB>is a tetravalent organic group having one or more aromatic rings) and has a weight-average molecular weight in the range of 50,000-500,000; and the aromatic polyimide can be obtained by imidizing this aromatic polyamide acid. This aromatic polyimide can offer a tensile modulus at 23°C of 2-5 GPa, a hygroscopic degree of 1.5 wt.% by weight or less, a thermal expansion coefficient of 35 ppm/K or less and a glass transition temperature of 350°C or higher. COPYRIGHT: (C)2009,JPO&INPIT
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