Patent GB-1045990-A (GB)
Title: Process for improving the crimpability of composite filaments
IPC: D02G1/14
Filed: 1964-10-05
Abstract: 1,045,990. False-twist apparatus; crimping fibres. KANEGAFUCHI BOSEKI KABUSHIKI KAISHA. Oct. 5, 1964, [Oct. 5, 1963; Nov. 12, 1963], No. 40412/64. Headings DID and D1F. [Also in Division B5] A process for improving the latent crimpability of a composite filament in which at least two different synthetic fibre forming polymers exist as adherent, substantially distinct and separate components arranged in an eccentric relation along the length of the filament, comprises drawing said filament and, subsequently or simultaneously, stressing the filament by twisting and untwisting it and/or by bending it in a zigzag fashion to develop residual strains in the filament which are different at different parts of the cross-section thereof. The filament may be twisted after drawing and the number of twists imparted to the drawn filament may be at least ten per centimetre. Alternatively the filament may be stressed by imparting a false twist to it, in which case the number of false twists imparted to the filament is at least ten per centimetre, or if stressed by bending in a zigzag fashion this may suitably be effected by means of a stuffer box. In any case, the latent crimpability is made actual by subsequent heat treatment, e.g. by steaming. Preferably said synthetic fibre forming polymers are two different polyamides which are simultaneously spun in side by side relation. One of the said polyamides may be poly e caproamide and the other a co-polymer of #   caprolactam and terephthalamide. Alternatively one of the said polyamides may be poly etacaprolamide and the other may be polyhexamethylene sebacamide. In a preferred method a false twist is imparted to the filament by means of a rotary snubbing pin device the axis of which is substantially parallel to the axis along which the filament is drawn. Figs. 15 and 16 illustrate suitable rotatory snubbing pin devices, which may be suitably used in the apparatus Fig. 14 (not shown). In Fig. 14 an undrawn filament is withdrawn from spool 1, passed through thread guides 2 and 3 successively, and then passed in multiple wraps about driven feed roll 4 associated with separator roll 5. From feed roll 4, the undrawn filament passes to rotatory snubbing pin device 6 which is rotated by a suitable driving device, e.g. a running belt or directly coupled motor. The filament is drawn in frictional contact with the pin of snubbing device 6 under the urging of draw roll 7 and associated roll 8. Draw roll 7 has a higher peripheral speed than feed roll 4, so that the filament is stretched to several times its original length. The filament is then led to wind-up device 9. In Figs. 15 and 16, the rotatory snubbing pin device has two or more crossed or grid like pins P mounted thereupon, about which filament A makes one or more wraps, so that the necking point of the filament being processed can be fixed around the pins. By means of the rotation of rotatory snubbing pin device 6, the axis of the rotation of which is parallel to the axis of the filament, the filament is twisted between feed roll 4 and rotatory snubbing pin device 6 and is untwisted between rotatory snubbing pin device 6 and draw roll 7. If an ordinary fixed snubbing pin of a conventional drawing apparatus is replaced by the rotatory snubbing pin device as described above, a torsional strain can be imparted to the filament by a so-called false-twisting simultaneously with the drawing of the filament. Examples are given.