Composite spun yarn and process for producing the same

#There are various processes or means for producing yarns by drafting a sliver or roving. The most general process for forming yarns comprises rotating a heavy package inserted into a spindle so as to give a true twist to a continuous bundle of short fibers. Such processes include for example ring spinning, mule spinning and flyer spinning. The spinning speed of these spinning processes is theoretically at most 30 m/min and a higher speed is not expected. On the other hand, the open-end spinning, which comprises temporarily breaking the continuity of the bundle of short fibers and feeding fibers one after another to the end of a yarn which has been already formed, while twisting the yarn, is being spotlighted. This process is now largely employed for production because of its higher productivity as compared with the former. By this process, however, the production of fine count yarns is difficult and the spinning speed remains at 2-3 times that of the former. Thus this process has not yet reached the stage of innovation. Recently, various proposals have been made on processes for producing yarns by utilizing false twist, without breaking the fiber bundle. It is well known that the productivity of these processes is markedly high in comparison with the ring spinning process. Representative of such processes is U.S. Pat. No. 3,079,746 (Fasciated Yarn Process and Apparatus for Producing the same) published on Mar. 5, 1963. As seen from its Examples, the spinning speed in the case of synthetic fibers is 914 m/min, showing a sufficient novelty indeed, but when cotton for example is used, the speed is as low as 36.6 m/min. Deviated from spinning processes of yarns, U.S. Pat. No. 3,427,647 (Wrapped Yarn Product and Process for Preparing Wrapped Yarns) published on Feb. 11, 1969 discloses a process for producing peculiar yarns. This process, intended to obtain an extremely thick covered yarn for use in non-textile fields, comprises wrapping a single filament yarn or a plurality of filament yarns around a plurality of yarns or filament yarns over nearly the whole periphery, with the twisting step being replaced with a false twist step. Anyway, there has not yet appeared any high speed spinning technique of a bundle of short fibers in the form of fleece. In the twisting or yarn forming step in both above-mentioned patents, a false twist apparatus utilizing air equipped with two air nozzles is used.

#The present invention relates to a process for high speed spinning to obtain a novel composite spun yarn consisting mainly of short fibers and to the structure of said composite spun yarn. More specifically, the invention is concerned with a process for producing a composite spun yarn and the structure of said yarn, which process comprises leading a fleece-shaped bundle of short fibers drafted by a drafting apparatus to a single gas false twist member where the bundle of short fibers is temporarily false-twisted in one direction; and feeding to the twisting zone of the bundle of short fibers an extremely fine filament yarn below 50 denier preferably in contact over a rotary body, with the balloon of the bundle of short fibers being substantially removed, at a sufficiently low tension and at a speed faster by 50-90% than the spinning speed of the bundle of short fibers, thereby reciprocating the feed point of multifilament yarn along the bundle of short fibers for a length over 50 millimeters through a fixed yarn guide positioned at a considerable distance from said feed point by utilizing the twisting force by the false twist member and not by mechanical traverse, whereby the bundle of short fibers is rendered non-twisted after passage through the false twist member and the bundle of short fibers is restrained along its periphery by the multifilament yarn within one-directional spirals and two-directional complex spirals.

#The primary object of the present invention is to rationalize the spinning process. Namely, the present invention provides a process which enables the production of a spun yarn at a speed 5-10 times higher than the ring spinning process. Also, the invention provides an energy economizing system such that only a single gas twist member is used in the formation of yarns. Further, in terms of yarn count, the invention enables the spinning of a single yarn up to 100 count (metric) at high speed which cannot be obtained by the open-end spinning process. Since the increasing of spinning-speed is very difficult especially for a ring spinning frame which is most widely used at present, the attainment of such speed-up has been a strong desire in the industry.

#FIG. 1 is a sketch showing an example of practice of the present invention.

#FIGS. 2 and 3 are pictures explaining the action, the former showing a side view and the latter a plan.

#FIG. 4 is a picture showing the appearance in the twisting zone of the composite spun yarn composed of X and Y portions.

#An example of the process of the present invention will be explained by reference to the sketch of FIG. 1. 1 is a roving of short fibers which is spun by being fed to the drafting apparatus shown as 9. 7 is a gas false twist member which is preferred to be of the conventional air vortex type. The gases to be used include air and other gases. 10 is a friction roller which is an example of rotary bodies. 15 is a winding apparatus. 2 shows delivery rollers of the drafting apparatus. 3 is a package of a multifilament yarn which is to be wrapped around the roving 1. 4 is a fine multifilament yarn. 5 is a take-up package. 6 shows take-up rollers. The gas false twist member 7 provides false twist for the fleece-shaped bundle of short fibers spun from the drafting apparatus 9, but the fiber bundle is untwisted after passing through the false twist member. Therefore, without use of a special intertwining yarn or a fiber fixing agent, the resulting fiber bundle cannot be formed into yarn. In a special case where the fibers contained in the bundle are sufficiently long, a yarn can be formed by binding the fibers with each other at the end portions of the fibers, as disclosed in the above-mentioned U.S. Pat. No. 3,079,746. However, speed-up of yarn production using cotton fibers is extremely difficult. Therefore, in the present invention, another yarn, i.e. an intertwining yarn is introduced which is spirally wrapped around the bundle of short fibers to restrain it. To form spirals around the fiber bundle, it is necessary to supply an intertwining yarn which traverses along the length of the fiber bundle. In the process of the present invention, an extremely fine continuous multifilament yarn 4 below 50 denier is used, which is fed at a rate in excess with respect to the spinning speed of the bundle of short fibers while passing in contact over the friction roller 10 to the bundle of short fibers 14 at the upper stream of the false twist member 7 through a tension controller 12 which enables the multifilament yarn 4 to maintain a suitable tension and through a fixed guide 13, with the balloon of the bundle of short fibers 14 being removed by a balloon removing device 8, so that the multifilament yarn 4 is spirally wrapped along and around the bundle of short fibers 14. Where a large spinning speed is provided, the tension controller 12 may be dispensed with. If necessary, an air feeder 11 may be positioned before or after the friction roller 10 so that the filament yarn 4 can be fed at a desired tension.

#The process for producing a yarn covered with a filament yarn by means of balloon-phenomenon is known from U.S. Pat. No. 3,427,647. By this process, however, it is utterly impossible to obtain a spun yarn from fleece, because this patent is directed to another purpose. As a result of our intensive study, we have attained to this epoch-making invention which makes possible the high speed spinning of the bundle of short fibers in the form of fleece, as previously mentioned. The spun yarn in accordance with the present invention is provided with numerous non-twisted short fibers, most of which do not contribute to the yarn strength in radial directions, and the yarn also has one-directional spiral portions which cover more than half the length of the yarn.

#Accordingly, the key point of the present invention is to let out a uniform, draft unevenness-free fleece from the delivery rollers of the drafting apparatus and to feed a fine multifilament yarn to excess by 50-90% in the mean value as compared with the feed by the delivery rollers. As mentioned in the Examples, when the excess feed surpasses 100%, the spirals become loose and this lowers the yarn strength to a great extent and impairs the appearance and touch of the yarn. Also, when the excess feed is less than 50%, the tension of the filament yarn becomes so high that the bundle of short fibers is pulled toward the supply side of the filament yarn and finally the twist does not reach the drafting rollers, so that yarn breaking is caused. Thus, to produce a good spun yarn, the feed amount of the filament yarn should be controlled by bringing it in contact with the friction roller.