Wire coating process
AssigneeThe Goodyear Tire & Rubber Company
InventorsJoseph N. Feil, John E. Hrivnak
Life of this patent
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Abstract
Wire which has been coated with a polymeric material is useful in a wide variety of applications. One such application is as a winding for electrical equipment such as motors, transformers, magnetic coils, relays and the like. Generally, coated wires of this type have been prepared by coating the wire with multiple layers of a solution of the coating material. It has been determined that metal wires can be satisfactorily coated with a specific type of thermoplastic composition in a single layer without using solvents. This process utilizes a tubing type cross-head die with the thermoplastic composition comprising a mixture of 80% to 99% by weight polyethylene terephthalate and from 1% to 20% by weight of polyethylene, polypropylene, or a mixture thereof.
Claims18
A process for coating a wire with a thermoplastic composition to a desired thickness in a single pass comprising:
- (1) preheating the wire to a temperature of about 150.degree. C. to about 325.degree. C.;
- (2) passing the wire through a tubing type cross-head die which is at a temperature of about 255.degree. C. to about 350.degree. C.;
- (3) extruding the thermoplastic composition into a tube which surrounds the wire which is exiting the tubing type cross-head die at a speed lower than that at which the wire is exiting the tubing type cross-head die;
- and
- (4) applying a vacuum to the die cavity so as to cause the tube of thermoplastic composition to collapse onto the wire as it exits the tubing type cross-head die;
- wherein the thermoplastic composition is comprised of 95 to 98 weight percent PET and from 2 to 5 weight percent of at least one member selected from the group consisting of polyethylene and polypropylene.
A method of manufacturing insulated electric wire which is designed to be used in the manufacture of windings for electrical equipment, comprising the steps of
- (1) heating a metal wire to a temperature of from about 150.degree. C. to about 325.degree. C.;
- and
- (2) extruding a polyethylene terephthalate blend comprised of about 95 weight percent to about 98 weight percent PET and from about 2 weight percent to about 5 weight percent of at least one member selected from the group consisting of polyethylene and polypropylene onto and around the metal wire with a tubing type cross-head die at a temperature of from about 255.degree. C. to about 350.degree. C.
Dependencies are inferred from the claim text.