Patent GB-1112938-A (GB)
Title: Method of producing synthetic fibres having non-circular sections and spinneret means therefor
IPC: D01D5/253
Filed: 1965-11-26
Abstract: 1,112,938. Spinnerets. KURASHIKI RAYON KABUSHIKI KAISHA. 26 Nov., 1965 [26 Nov., 1964], No. 50460/65. Heading B5B. A polymer solution is dry-spun through a spinneret having one or more groups of from two to six orifices of circular cross-section, each orifice in the or each group being from 1�0 to 5�0 mm. distant from at least one other orifice in its group (between centres) and each orifice being from 0�05 to 1�0 mm. across, and the filaments coming from the orifices in the or each group are caused to adhere while still tacky, but when solid enough not to coalesce as a single circular filament. An orifice unit comprising a number of groups of orifices is suitable for facilitating the spinning of a multifilament thread. In such a spinneret, the groups of orifices in each orifice unit may be from 4 to 12 mm. apart and more than one of such orifice units may be present (suitably from 2 to 8) to facilitate spinning of a number of multi-filament threads simultaneously. As shown in Fig. 3, the orifices in each group, or in at least some groups, may originate from a well common to the group in the back of the plate forming the spinneret surface (see 12, 14, 16 of Fig. 3). Alternatively, some or all orifices may extend completely through the thickness of the plate forming the spinneret surface, as in 13, 15 and 17, of Fig. 3. Some or all of the orifices in some or all of the groups may be at right angles to the spinneret surface, and some or all of the orifices in some or all of the groups may be angled with respect to the spinneret surface (14, 16, 15, 17 of Fig. 3) in such a direction as to throw the spun filament from the angled orifice towards another spun filament or filaments from the orifice or orifices in the same group. The spinneret may also contain one or more orifices at right angles and one or more angled orifices (as in 14 and 15 of Fig. 3), within some or all of the groups. The orifices in the, or each group, may have the same or different diameters, and may be angled with respect to the spinneret surface, in such a direction as to throw the spun filaments from each orifice in the group together. Orifices in the or each group may be of at least two different diameters and some or all of the larger diameter orifices in each group may be at right angles to the spinneret surface, and some or all of the smaller diameter orifices may be angled to throw their spun filaments on the spun filaments from the larger diameter orifices. Materials suitable for such dry spinning include polyvinyl alcohol, polyurethanes, polyacrylonitrile and polyvinyl chloride. Filaments of non-circular cross-section may be thus obtained having deniers from 1�5 to 6, especially 1�5 to 4. Suitably the filaments in each group contact at a distance of from 0�5 to 40 cms. from the spinneret and especially at from 2 to 20 cms. from the spinneret. Using a group of orifices as in 3 of Fig. 2, filaments of the form 4 may be produced if the orifices are the same diameter, and of the form 5 if the orifices are different diameter. Similar remarks apply to the spinneret groups shown in 6 and 9 of Fig. 2 which produce the filaments 7 and 10 respectively where the orifices are the same diameter, and 8 and 11 where the orifices in the group are of different diameter. Examples are given relating to the dry-spinning of polyvinyl alcohol solutions.