| 摘要 |
PURPOSE: Provided are a polyamide-imide polymer which shows a sufficient heat resistance and a suitable viscosity(which is not extremely high), and thus excellent processability and productivity when coated. CONSTITUTION: The polyamide-imide polymer has a structure of formula 9(wherein each of m and n is a mole fraction of each monomer, 0.7<=m<=0.9, and 0.1<=n<=0.3). The polymer has the molecular weight of 30,000 to 50,000. The polymer is prepared by reacting a trimellitic anhydride and pyromellitic anhydride with 4,4'-methylenediphenyldiisocyanate in highly polar solvents. The enamel copper wire is produced by applying the polymer on an enamel copper wire, and curing the wire at high temperature to form a final enamel copper wire.
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