GB992346A - Process and apparatus for coating wire and the like - Google Patents

Abstract

992, 346. Coating wires &c. OSBORN MANUFACTURING CO. June 28, 1962 [Aug. 11, 1961], No. 24886/62. Headings D1L and D1P. A method of forming a beaded coating on wire, thread, synthetic filaments or composite bundles thereof comprises coating the wire or the like with a liquid which has a surface tension such that it forms into longitudinally spaced beads on the wire or the like, the beads then being solidified. In a preferred form the beads are substantially uniform in size and spacing. In Figs. 1 and 2 a plurality of wires from a roll 18, passes about a grooved roller 12a and is coated with primer liquid in a trough 20a which it enters through openings in a layer of closed cell polyurethane foam 22, acting as a seal. The primer coating is then doctored by a die 21a before having it solvent driven off by the passing of the wire through the electrically or steam coil heated chambers 13b, 13a. The wires then pass about rollers 11, 16, 17 and about grooved roller 12b before entering a second trough 20b (similar to trough 20a) to have coating liquid applied thereto; the thickness of the coating is regulated by dies 21b so that beads form on the wires before they enter chambers 13b, 13a in which the beads are solidified; the coated wires which are suitable for the bristles of rotary wire brushes, are wound on to a take up roll 19. In the above process the primer is preferably a solution of rubber in methyl ethyl ketone while the coating material is a plastisol comprising 100 parts of P.V.C. resin in 25 parts dioctyl phthalate and 25 parts dioctyl adipate with 3 parts cadmium 2-ethylhexanoate as a heat stabilizer. Other coating materials may be solutions or melts of phenol-formaldehyde resins, polyurethane resins or preferably thermoplastic resins e.g. vinyl resin, polystyrene resins, polyacrylate resins, nylon resins or linear polyesters. Particularly preferred coating materials are plastisols (i.e. a dispersion of fine particles of thermoplastic resins in a plasticizer) which form solid solutions on heating. In other fields molten metals, solutions of gums and certain waxes may constitute the coating material. Examples detailing the speed of wire advance, the temperatures of chambers 13a, 13b and the times taken for the wire to pass from die 21b to chamber 13 and to pass through chamber 13 are given. Details are also given of suitable diameters for the primer and coating dies for a range of wire gauges.