Patent GB-1130497-A (GB)
Title: Process for the high-speed funnel spinning of viscose filaments
IPC: D01F2/06
Filed: 1967-10-02
Abstract: 1,130,497. Funnel spinning of viscose filaments. ASAHI KASEI KOGYO K.K. 2 Oct., 1967 [21 Oct., 1966; 30 May, 1967 (2)], No. 44670/67. Heading B5B. A viscose spinning process of the funnel spinning type is effected at an increased spinning velocity of 140 to 300 m. per min., said process being characterized in that the flow velocity of the bath liquid as measured in the straight zone of the funnel stem is selected to be lower by 35 to 80 m. per min. than that of the extruded viscose filaments as measured at the same place at above specified. Preferably, the mean flow velocity of the bath liquid as measured at the level of the extrusion orifices of the spinneret amounts to 15 to 60 cm. per min., which velocity is then increased at a rate of 0À8 to 3À0 m. per min. for each increment of 1 mm. in downward distance remote from said level within the enlarged head zone formed above the straight zone of the funnel stem and that the immersed length of the extruded, coagulated and regenerated viscose filaments in the overall bath zone consisting of both said zones is defined by the following formula: wherein Y in cms. stands for said immersed length of the extruded viscose; and X represents in m. per min. the mean spinning velocity of the extruded viscose. Desirably, the bath liquid is led to flow through a swirling zone occupying a length of the lower end of said funnel stem zone and formed into a spiral fluid passage. In the apparatus of Fig. 1, the funnel forming the coagulation bath is preferably 130 to 450 cm. long, and of outside diameter from 3 to 7 mm. The lower portion of tube 1 is formed into a threaded or spiral tube part 2, constituting a swirling zone, the bore size of the funnel depending on the spinning velocity of the viscose. With increase of this velocity, the tube bore must correspondingly be larger. On the other hand, the spiral angle and the value of spiral pitch is preferably reduced with increase of the strength of each filament to be spun, as this assures easier separation thereof from the bath liquid. At the top of funnel 1, is an enlarged head chamber 3, consisting of an upper cylindrical part 4 and a cone-shaped part 5, said chamber being rigidly united at its bottom end with tube 1, and a conventional spinneret 6 projects through the top wall 7 of chamber 3 into the interior space thereof. Spinneret 6 is connected by a feed pipe 8 and pump 9, to a viscose solution reservoir. Near the top wall 7 of the chamber 3, an inlet socket 12 is provided, rigidly attached to the side wall of the chamber, said socket being connected by a supply piping 13 with a pump 14 supplied with coagulation bath liquid from the reservoir. Below the lower end of funnel 1, is a liquid collecting tray 10, in the neighbourhood of which is a deflector guide 11, which may be freely rotating or positively driven. In the modified funnel head of Fig. 3, there is provided a perforated baffle ring 15 within the chamber 3a for the avoidance of turbulent inlet flow of the bath liquid. Additionally, the lower end of the funnel at 1a is formed into a straight tube. Other constituents of the spinning assembly are substantially as before. An example describes the spinning of a viscose solution containing 8À0% by weight of cellulose, and having an alkali concentration of 5À5% expressed as sodium hydroxide, and a Hottenroth number of 11 into a conventional coagulating bath containing sulphuric acid, sodium sulphate, and zinc sulphate and maintained at 62 C. The process of the invention enables viscose filaments to be spun at increased speeds without difficulty arising in the separation of the spun filaments from the strongly flowing-down stream of the bath liquid at the lower end of the funnel.