PRODUCTION METHOD OF INSULATION WIRE

PROBLEM TO BE SOLVED: To provide a flat enameled wire that is excellent in flexibility and heat resistance, has an insulation layer of which delamination is suppressed from occurring and can be preferably produced by rolling.SOLUTION: An insulation wire includes a conductor and an insulation layer provided on an outer periphery of the conductor. The conductor has a rectangular cross-section having a pair of mutually facing long sides and a pair of mutually facing and convex to the outside short sides. The insulation layer contains a polyimide that contains a tetracarboxylic acid component unit (a) containing 15 to 45% by mole of benzophenonetetracarboxylic anhydride unit and 55 to 85% by mole of pyromellitic anhydride units and a diamine component unit (b).SELECTED DRAWING: Figure 1 【課題】可撓性、耐熱性等に優れるとともに、層間剥離の発生が抑制された絶縁層を有し、圧延により好適に製造することのできる平角エナメル線を提供する。【解決手段】絶縁電線は、導体と、この導体の外周に設けられる絶縁層とを有する。導体は、互いに対向する一対の長辺と、互いに対向してかつ外側に凸状となる一対の短辺とを有する矩形状の断面を有する。絶縁層は、ベンゾフェノンテトラカルボン酸無水物単位１５〜４５モル％と、ピロメリット酸無水物単位５５〜８５モル％とを含むテトラカルボン酸成分単位（ａ）と、ジアミン成分単位（ｂ）とを含むポリイミドを含む。【選択図】図１