PRODUCTION OF STRAND ELEMENT WIRE INSULATING MATERIAL

PURPOSE:To form a dense and uniform oxide film on the element wire surface and to obtain an element wire insulating material having superior characteristics easily in a short time, by immersing a copper strand wire conductor in an aqueous solution of surface active agent and then heating it under an ammoniac atmosphere. CONSTITUTION:The strand insulated conductor 1 is immersed in the aqueous solution of surface active agent such as dioctyl sulfosuccinate or the like, which is maintained at about 80-90 deg.C atmospheric temp. for >= about 2.5hr, especially >=about 4hr, in a heating vessel 2 having hermetically sealed structure containing, e.g., about 0.5-5% aqueous ammonia 3. By this oxidation treatment, an insulating film mainly composed of cupric oxide, excellent in insulating characteristics, is formed on the element wire surface. It is desirable that the concentration of the aqueous solution of surface active agent is about 0.1-1.0% and it is also preferable to use, as the aqueous solution of surface active agent, an aqueous ammonia in which the surface active agent is dissolved.