Patent GB-1106919-A (GB)
Title: A method of improving spinnability and property of conjugate filaments and spinning apparatus therefor
IPC: D01F8/04
Filed: 1966-08-02
Abstract: 1,106,919. Spinneret for conjugate filaments. KANEGAFUCHI BOSEKI KABUSHIKI KAISHA. 2 Aug., 1966 [2 Aug., 1965; 15 July, 1966], No. 34682/66. Heading B5B. A spinneret for producing conjugate filaments is characterized in that it comprises two filter blocks 2, 21 provided with melt reservoirs connecting to separate tubes 5, 5<SP>1</SP> for transferring the spinning melts, a nozzle plate IV provided with at least one orifice 7, a distributer plate III, provided between said filter blocks and said nozzle plate and provided with two channels 5, 5<SP>1</SP> to introduce two spinning melts from said melt reservoirs to the rear of the same orifice separately, means for controlling the temperatures of the two melts separately (heaters 11, 11<SP>1</SP>) and heat insulating means 8 for retarding transmission of heat between the spinning melts. As shown, the heat insulating means may be heat insulators provided between the two melt reservoirs. Such insulators are suitably made of glass fibre or asbestos and at least one row of ventilating holes 13 may be provided in the heat insulator. Suitably the means for controlling temperature are electric heaters to heat each half spinneret. Alternatively, the means for controlling temperature may be jackets to heat each half spinneret divided into two parts, in which heating media are circulated (e.g. jackets 11, 11<SP>1</SP> containing heating fluid 14, 14<SP>1</SP> in Fig. 5). A suitable heating medium is that sold under the Registered Trade Mark " Dowtherm". The spinneret of Fig. 2, is suitable for spinning side-by-side filaments; that of Figure 5 is suitable for spinning eccentric core-and-sheath filaments. In this construction an inner orifice 1 is inserted into an outer orifice 7 in such a positional relation that the central axis of the inner orifice is eccentric to the centre axis of the outer orifice (Fig. 8) and one end of the channel 5 of the distributer plate III is passed to the rear of the inner orifice. Utilizing the spinneret disclosed, a conjugate filament may be spun from two fibre-forming thermoplastic synthetic linear polymers, the melt viscosities of which are different at the respective optimum spinning temperatures, by melting them separately, and then extruding the molten polymers simultaneously from the same orifice to form a unitary filament, in which the polymers are arranged eccentrically along the length of the filament, the temperatures of the polymers being regulated prior to extrusion to keep the melt viscosity ratio within the range of 0À4 to 2À5 as the molten polymers are extruded Such separate heating may be effected in the spinneret, or alternatively may be effected prior to the spinneret to reduce the melt viscosity ratio, and this ratio then maintained at its reduced level until the extrusion of the molten polymers. Desirably, the ratio of melt viscosity of both polymers upon extrusion is within the range 0À50 to 2, preferably 0À8 to 1À25. In a preferred method, the polymer having higher melt viscosity is separately heated prior to extrusion to a temperature higher than its optimum spinning temperature but lower than the temperature 150 C. higher than the melting point of the polymer, selectively to decrease its melt viscosity. Preferably, the optimum spinning temperature is a temperature 20 to 50 C., desirably 30 to 40 C. higher than the melting point of the polymer. Preferably, the polymer having the higher melt viscosity at its optimum spinning temperature is heated to a temperature higher than its optimum spinning temperature but less than 100 C. higher than its melting point. The polymers may be selected from polyamides, polyesterethers, and polyolefines. Desirably, both polymars are polyamides, either the same kind of polyamides having different intrinsic viscosity, suitably at least 0À20 difference in intrinsic viscosity and especially at least 0À25, or alternatively the polyamides may consist of homopblyamide and copolyamide. In a preferred method two polyamides are extruded in a side by side relationship; in another preferred method a polyamide and a polyester are extruded in an eccentrical core and sheath relationship. In a further preferred embodiment the polymers are polyamide and polyolefin and these polymers are extruded in an eccentric core and sheath relationship. Filaments may also be made from two polymers which are respectively polyester and polyester-ether. A list of suitable polymer combinations is given. These include polycaproamide/polyhexamethylene adipamide, polycaproamide/polyhexamethylene sebacamide, polyhexamethylene adipamide/polyamino-undeconoic acid; a combination of homopolyester and homopolyester-ether e.g. polyethylene terephthalate/ polyethyleneparaoxybenzoate; a combination of homopolyolefins, e.g. high density polyethylene/low density polyethylene; high density polyethylene/isotactic polypropylene; a combination of homologous homopolymer and copolymer, e.g. polycaproamide/polycaproamidepolyhexamethylene isophthalamide copolymerpolyhexamethylene adipamide/polyhexamethylene adipamide-polyhexamethylene terephthalamide copolymer, polyethylene terephthalate/ polyethylene terephthalate-polyethylene isophthalate copolymer; a combination of different kinds of polymers, e.g. polyamide/polyester, polyester/polyolefin, polyamide/polyolefin, polysulphonamide/polytirea, polyvinyl chloride/polyvinylidene chloride. Thermoplastic synthetic linear polymers, e.g. polyurethane, polyoxymethylene, polypivalolactone and polychlorotrifluoroethylene may also be used by combining with the above-mentioned various kinds of polymers. Conventional additives may also be present.