Method of obtaining of wires by extrusion of a molten mass

摘要

In a melt-spinning process, a nozzle is used having such a high-bore diameter that the ratio between the injection velocity in metres per minute and the thread diameter in millimetres prior to final stretching is between 20 and 80, the injection velocity being maintained between 2.9 and 7.2 metres per minute. The thread diameter is measured after winding on the bobbin, the thread being preliminarily stretched during spinning. Hollow threads may be made similarly, and the Figure shows a suitable nozzle. The body 1 has bores 2 communicating with undercut recesses 3 fed with melt via passages 4, 5. A core 7 is fitted into a PICT:0835476/IV (a)/1 bore 6 coaxial with bore 2 so that the remaining part of bore 2 forms an annular orifice. Core 7 also contains a bore 8 connected to supply pipes 9, 10 through which an inert gas, e.g. nitrogen, may be supplied. In an example, a melt of polycaprolactam is spun at 275 DEG C. through a 4-aperture nozzle having individual apertures of diameter 1 mm., using an injection velocity of 7.2 metres/min. and a withdrawal speed of 720 m/min. The thread diameter measured after winding up is 0.1 mm. After further stretching to a ratio of 4:1, the thread diameter is 0.05 mm., corresponding to 20 denier.