TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Process: The amine component is obtained by copolymerizing p-phenylenediamine, m-phenylenediamine, chloro-p-phenylenediamine, 4,4'-diaminodiphenyl ether, 2,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 2,4'-diaminodiphenylmethane, and 4,4'-diaminodiphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 1,5-diamino naphthalene, 3,3'-dimethyl benzidine, 3,3',5,5'-tetramethyl benzidine, 3,3'-dichloro benzidine, 2,2'-dichloro benzidine, 3,3',5,5'-tetrachloro benzidine, 2,4-bis(( beta )-amino-t-butyl)toluene, and bis(p-( beta )-amino-t-butyl phenyl)ether. The acid anhydrides compound is obtained by copolymerizing aromatic-carboxylic-acid di-anhydride compound such as compound pyromellitic acid di-anhydride compound, 2,3,6,7-naphthalene tetracarboxylic acid di-anhydride compound, 3,3',4,4'-biphenyl tetracarboxylic acid di-anhydride compound, 1,2,5,6-naphthalene tetracarboxylic acid di-anhydride compound, 2,2',3,3'-biphenyl tetracarboxylic acid di-anhydride compound, 2,3,4,5-thiophene tetracarboxylic acid di-anhydride compound, 2,2-bis(3,4-dicarboxyphenyl)propanoic acid di-anhydride compound, bis(3,4-dicarboxyphenyl)sulfonic acid di-anhydride compound, and 3,4,9,10-perylene tetracarboxylic acid di-anhydride compound. The aromatic polyimide component is maintained at 50 mol% or less, such that strength of polyimide component is reduced when copolymerization of the aromatic diamine or the aromatic-carboxylic-acid di-anhydride is carried out. EXAMPLE - 4,4'-(1,3-phenylene bis(1-methylidiene))bis-aniline (4.209 g) and N,N-dimethyl acetamide (20 ml) were mixed at 20 degrees C, and 4,4'-oxydi phthalic acid di-anhydride (3.8096), and N-methyl-2-pyrrolidone (12 ml) were added to the resultant mixture. The mixture was stirred for 6 hours, and polyamic-acid dope liquid was obtained. The dope liquid was coated on a glass plate. The coated plate was dried at 240 degrees C for 6 hours, and polyimide film was obtained. The polyimide film had elasticity modulus of 2.8x 104 kgf/cm2, and elongation of 18.2%.