Patent GB-291485-A (GB)
Title: Improvements in or relating to the covering of wire, thread-like and filamentary material and the like with indiarubber, gutta percha, balata or similar materials or compounds thereof and apparatus therefor
IPC: B29C70/68
Filed: 1927-01-28
Abstract: 291,485. Dunlop Rubber Co., Ltd., Twiss, D. F., and Murphy, E. A. Jan. 28, 1927. Indiarubber threads.-A process for coating wire, thread-like, or filamentary material with indiarubber, balata, guttapercha, and similar materials or mixtures thereof consists in passing the wire, &c. through a bath containing a concentrated and compounded aqueous dispersion, in the form of a cream or viscid fluid. containing indiarubber, guttapercha, balata, &c., causing it to emerge therefrom coated or covered uniformly, and drying the coating or covering without, allowing it to contact with any solid foreign body. The .coating may be vulcanzied. The dispersions may be prepared by concentrating natural or artificial dispersions, or by incorporating additional materials such as protective colloids or stabilising agents, and compounding ingredients comprising reinforcing agents, diluents, softeners, vulcanizing agents, anti-agers and colouring matters. with aqueous dispersions of rubber or rubber-like materials and concentrating the whole by drying. The dispersions may be prepared as described in Specificatiion 290,313. The filamentary material may consist of an amorphous colloidal material drawn out into a thin thread, which can be absorbed or partially absorbed into the rubber layer. Filaments of tacky or resinous rubber, or of glue mixed with rubber, may be used, or artificial silk fibres, sodium silicate, resins, &c. The wire or thread-like or fiilamentary material is passed into a bath containing the dispersion, under a grooved roller immersed therein, and upwards to leave the bath through a suitably shaped tube of glass or non-corroding material, preferably circular in cross section and provided with a constricted part disposed near the level of the surface of the liquid. A suitable dispersion consists of 8 parts of zinc oxide, 2.5 parts of sulphur, 1 part of lamp black, 20 parts of talc, 15 parts of whiting, 2 parts of paraffin wax (previously emulsified in water) and 1 part of finedy ground mineral rubber, mixed with 100 parts of water containing 0.1 part of caustic potash, 0.3 part of oleic acid and 0.3 part of casein. Ammonia preserved latex is then added in sufficient quantity to introduce 60 parts of rubber, caustic potash having been added to the latex so that the 60 parts of rubber contain 0.4 part of caustic potash. The whole is then concentrated by evaporation under gentle continuous agitation. The mixture is then allowed to cool, and ammonia, and if desired, an accelerator such as 0.3 part of diethyl ammonium-diethyl dithiocarbamate, is added. In another example 20 parts of whiting, 2 parts of zinc oxide, 1 part of organic dye, e.g. toluence-azo-naphthol, 1¢ parts of sulphur, 0.5 part of tetramethyl thiuram monosulphide, 3 parts of petroleum jelly (emulsified in water), and 8 parts of lithopone, are placed in a mixer together with 100 parts of water containing 0.3 part of oleic acid, 0.2 par of casein and 0.1 part of caustic potash. After a smooth dispersion has been obtained, sufficient latex is added to introduce 64 parts of rubber together with 0.5 part of caustic potash. The whole is then mixed and concentrated under gentle agitation. A dispersion containing 80 per cent of total solids may be obtained. In a further example, 16¢ parts of whiting, 25 parts of French chalk, 16 parts of zinc oxide and 2 parts of sulphur are placed in a mixer with 100 parts of water containing 0.1 part of casein, 0.1 part of casein, 0.1 part of oleic acid and 0.05 part of caustic potash. After a smooth dispersion has been obtained, sufficient latex to introduce 40 parts of rubber together with 0.5 parts of caustic potash are added, and the whole then concentrated under gentle agitation. Near the end of the concentration 0.5 part of piperidine piperidinecarbothionolate in 5 parts of water is added. A dispersion containing up to 80 per cent of total solids may be obtained. In a further example, 60 parts of rubber, 2 parts of lamp black, 10 parts of zinc oxide, 10 parts of whiting, 15¢ parts of French chalk, 0.5 part of piperidine piperidanecarbothionolate, 0.1 part of casein, 0.1 part of oleic acid and 0.6 part of caustic potash are mixed as in the preceding example. The apparatus is shown in Fig. 2. The wire or thread 1 passes downwardly through an orifice 2 into a bath 3 containing the dispersion 4, and is guided under a grooved roller 6. It passes upwardly out of the bath through a tube 8, preferably of glass, which is constricted at 9. The wire or filament draws a quantity of liquid 11 into the cup 10 formed above the constriction 9, and issues from a small surface of liquid, thus ensuring a smooth deposdt. The deposit is continuously dried and vulcanized by passing through a drying chamber 12, Fig. 3, over a pulley 13 and downwardly through a vulcanizing chamber 14, suitably heated.