Patent ES-350368-A1 (ES)
Title: Production of strands from fibrous material,particularly asbestos fibers
IPC: D02G3/20
Filed: 1968-02-10
Abstract: In the production of fibrous strand by passage of a dispersion of fibres, consisting wholly or mainly of asbestos in a liquid containing a dispersing agent, through a shaping nozzle and solidification of the shaped dispersion by subjection thereof to the action of a coagulating agent, the nozzle (as may be formed by rollers, possibly co-operating with a mandrel disposed therebetween) has a cross-section, e.g. slit or star-shaped or annular, formed of one or more elongated parts so as to form a strand of corresponding cross-section and the shaped dispersion is withdrawn and conveyed from the nozzle by a moving surface of a carrier body, e.g. a rotatable, cylindrical roller, adjacent the nozzle outlet and covered with the coagulating agent so that coagulation is initiated at the latest on the moving surface. The, at least partially, solidified strand is removed from the moving surface, e.g. by use of jets of air or water and if necessary, is further subjected to the action of the agent to complete solidification. The surface of the shaped dispersion not in contact with the carrier may also be contacted with coagulant applied by dipping, spraying or sprinkling and the strand may be twisted, optionally with prestretching, to form yarn or thread. Volatile or vaporizable organic components from the dispersing and/or coagulating agent(s) may be removed by after-treatment. A specific example of fibre dispersion comprises asbestos fibre, crystalline aluminium sulphate, wetting agent, i.e. equal parts of alkylbenzenesulphonate and water (or sodiumdodecylbenzenesulphonate) for which the coagulating agent may be a zinc sulphate solution. In the apparatus shown in Fig. 1, a fibre dispersion in container 1 emerges from a narrow nozzle, the width of which may be adjusted by movement of a pivoted wall 4 and the length of which may be adjusted by transverse movement of an internal wall, Fig. 6 (not shown) and is collected on a surface formed by a layer of polyurethane foam on a roller 6 and continuously wetted by coagulating agent supplied from a bath 8. Removal of the strand and excess liquid is effected by a roller 10 (assisted by an air nozzle 12) through the porous material of which water under slight pressure from a chest 13 is forced outwardly to facilitate detachment of the strand as it runs into a funnel 14 the wall of which is covered with flowing water. In a modification, roller 6, dipping into a bath, is replaced by a porous roller into which coagulating agent is supplied and flows through the roller wall to wet its surface. In the operation of the apparatus shown in Fig. 2, a carrier roller 20 rotates (a) about its own axis 21 to convey the strand or band 31 formed thereon by a nozzle 26 from which emerges a fibre dispersion supplied through pipe 25 and (b) together with nozzle 26, about an axis 23 in order to twist the detached coagulating or coagulated strand into a yarn. As shown in Fig. 7 the fibre dispersion 64 in container 61 contacts grooved rollers 62 dipping into coagulant bath 63 and a band 65 formed and advanced by passage through the gap between the rollers, passes through the coagulant, over a guide roller 66 to a stretching device 67 and the resultant band 68 passes to a funnel guide 69 of twisting and take-up apparatus. In another embodiment, Fig. 8 (not shown) the surfaces of the rollers corresponding to rollers 62 are supplied with coagulating agent by a jet system and stretching of the fibrous band is effected between such rollers and a succeeding pair of ribbed rollers.