Heat-resistant electrically insulated wires and a method for preparing the same

Claim 1

A heat-resistant electrically insulated wire comprising a conductor, at least one composite coating layer circumferentially enclosing the conductor, said composite coating layer being a mixture comprising an inorganic fine powder selected from the group consisting of Al 2 O 3 , BaTiO 3 , CaTiO 3 , PbTiO 3 , ZrSiO 4 , BaZrO 3 , MgSiO 3 , SiO 2 , BeO, ZrO 2 , MgO, clay, kaolin, bentonite, montmorrilonite, glass frit, mica, BN and silicon nitride, and mixtures thereof and an inorganic polymer selected from the group consisting of silicone resins; modified silicone resins; inorganic polymers having a skeleton comprising silicone, oxygen and one or more elements selected from the group consisting of C, Ti, B, Al, N, P, Ge, As and Sb and mixtures thereof, and at least one overcoat layer of a flexible organic resin circumferentially enclosing said composite coating layer in a sleeve-like non-adhered relationship, said organic resin being selected from the group consisting of a polyimide, a polyamide-imide, a polyester-imide, a polyhydantoin, a polyester, a polyparabanic acid, an aromatic polyamide, an aliphatic polyamide, a polyurethane, a fluoroplastic, a polyolefin, a polyvinyl formal, a polysulfone, an epoxide resin, a phenoxy resin, and mixtures thereof, wherein said composite coating layer has not artificially been fired and is adapted to be converted into a ceramic layer when exposed at elevated temperatures during use.