| 摘要 |
In the spinning of cuprammonium rayon by the funnel stretch-spinning process, the mean linear velocity of the precipitation liquid in the spinning funnel, in the region of the mean maximum velocity gradient of the filaments, is at the most 30 metres per minute lower than the mean speed of the filaments in this region. The mean maximum velocity gradient of the filaments is defined as the mean of the maximum velocity gradients of the individual filaments. The velocity gradient of a filament at any point along its path from the spinneret is defined as the slope at that point of a curve obtained by plotting the linear speed of the filament against the path travelled, this slope being expressed as the increase in filament speed per centimetre of filament path travelled. The mean linear velocity of the precipitation liquid in the spinning funnel through a cross-section of the funnel at any given point is defined as the volume of flow per unit time divided by the cross-sectional area of the funnel at that point. In an example, the draw-off velocity of the filaments is 150 metres per minute, the spinning bath temperature is 40 DEG C., the individual filament titre is 1.4 denier, the distance of the mean maximum velocity gradient of the filaments from the spinneret is 36 cm., the mean maximum velocity gradient of the filaments is 6.5 metres per minute per centimetre, the mean filament speed at the point of mean maximum velocity gradient is 75 metres per minute, the linear velocity of the precipitation liquid at this point is 60 metres per minute, and the volumetric rate of flow of precipitation liquid through the funnel is 4,200 c.c. per minute. The method enables higher spinning speeds to be used without increase in the frequency of filament breakage.
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