Abstract: An extrusion process for the manufacture of insulated winding wires. Part crystalline thermoplastic polycondensates with crystallite melting points above 170.degree. C., preferably above 250.degree. C., are extruded. Polyethylene terephthalate is the polycondensate of choice. These are filled with 5-15% by weight titanium dioxide. The result is the avoidance of fissure formation.

Abstract: A polyborosiloxane composition to be used for the formation of an insulating layer on an electric conductor comprises (A) a polyborosiloxane produced by the reaction of boric acid, a boric acid derivative, or a halogenated boron with a silane compound and a silicone oil, (B) a silicone resin or a synthetic resin having a nitrogen-containing heterocyclic ring in the molecule, (C) an inorganic filler, and (D) a common solvent for (A) and (B). An insulated electric wire excellent in thermal resistance is obtained by applying the composition to an electric conductor and baking the applied layer of the composition.

Abstract: New polymeric compositions based on polytetramethylene terephthalate (PTMT) polymers are disclosed. PTMT polymers are subject to embrittlement, especially at elevated temperatures and when a flame retardant is incorporated therein. This problem is substantially reduced by blending the PTMT polymer with a second polymer which has a flex modulus of 500 to 100,000 psi and a solubility parameter within .+-.1.5 of the PTMT polymer, for example an ethylene/vinyl acetate copolymer or a block copolymer containing polyether and polyester blocks. The compositions are particularly useful as wire insulation.