Method and apparatus for orienting an extruded polymeric wire coating

981,858. Coating wires by extrusion. HERCULES POWDER CO. Dec. 20,1963 [Dec. 24, 1962], No. 50483/63. Heading B5A. In a method of applying an orientated thermoplastic polymer coating to a wire, a wire 1 is drawn through a wire coating die 2 by take-up equipment 9 and thermoplastic polymer 3 is extruded around the wire 1 at a rate less than the linear velocity of the wire, the coated wire then being passed through a series of ball races 5 of gradually diminishing internal diameter to effect orientation of the polymer. Temperature conditioning of the polymer coating 3 may be accomplished by passing gas or liquid through chambers such as 4 and 7. A series of ball races 6 having the same internal diameter may be provided to " polish " the surface of the polymer coating. It is suggested that the ball races 5, 6 may be rotated about the axis of the wire as the coated wire is drawn through, to effect biaxial orientation of the polymer. Examples are given in which coatings of stereoregular polypropylene and poly-(3,3-bischloromethyl oxe. tane) are applied to single strands of copper and steel wire, respectively. The use of aluminium or tinned copper wire in single or multiple strands and of the polymers, polyethylene, polyethylene terephthalate, polyamides, polychlorotrifluoroethylene, polyvinyl chloride, and polyvinylidene chloride is suggested.