GB877416A - Methods and apparatus for producing "stretch" or "elasticizer" yarns - Google Patents

Abstract

Potentially crimpable yarn of organic hydrophobic thermoplastic material, e.g. polyamides, polyacrylonitrile and acrylonitrile copolymers, polyethylene glycol-terephthalate or cellulose triacetate, is converted into "non-torque" stretch yarn by advancing a running length thereof through an acutely angular path, such as may be provided by a blade edge, thence over a driven roll, the speed of which is adjustable with respect <PICT:0877416/IV (a)/1> <PICT:0877416/IV (a)/2> <PICT:0877416/IV (a)/3> to the speed with which the yarn is advanced towards the path, in order to control tension in the yarn after its passage through the path. The yarn may be hot-stretched beyond its elastic limit before arrival at the path, in accordance with the process and by means of the apparatus described in Specification 842,703. The yarn may pass through the path at room temperature, as described in Specification 558,297, or at elevated temperature, as described in French Specification 1,113,990, and be cooled by the driven roll around which the yarn is partially wrapped. In the apparatus shown in Fig. 1, yarn 16 from a supply 14 is advanced to and withdrawn from a sharpened edge 41 by roller means 33, 18: the yarn passes several turns around rollers or stepped-roller portions 21, 23, optionally over an electrically heated plate 28, several turns around a roll 34 (the periphery of which may be heated, in part at least, by an internal electrical element) and roll 36, over the edge 41 of a pivoted, adjustable blade 40, the temperature of which is lower than that of the roll 34, a partial wrap around roll 39, past a lubricating roll 43, one or more turns about portions 22, 24 of rollers 19, 20, and is guided to take-up means 48. The drive to the roll means 18, 33, between which the yarn is normally stretched on its forward path and allowed to contract, or at least is not stretched, on the return path, may include a variable ratio speed change, and the speed of roll 39 is adjustable. The roll 39 may cool the yarn as well as control yarn tension. As shown in Fig. 4, the yarn approaching and leaving the edge 41 lies in a plane not perpendicular to the edge, i.e. it is "skewed" thereabout. A second yarn heater may be interposed between rolls 33 and edge 41, in which case roll 34 is unheated (Fig. 5, not shown).