Spin of viscose

Fig. 12.7. Spinning of viscose rayon. Courtesy of Avtex Fibers, Inc.)...

EOY speeds are the most recent development in PET spinning (78). Properties are similar to HOY and appear to be limited by the differential cooling rate from filament surface to filament core. This leads to radial distribution of viscosity, stress, and, consequentiy, molecular orientation (75). Eiber tensde strength is limited. Nevertheless, speeds up to 7000 m /min are commercial and forecasts are for speeds up to 9000 m /min by the year 2000 (79). Speeds to 9000 m/min have been studied (68,80,81). 

The dark blue solution containing 5—10% of cellulose with a DP of 1000—2000 is filtered through a series of plate-and-frame filter presses using fine mesh metal screens to remove any particles that might block the spinneret holes. It is then deaerated under vacuum and stored ready for spinning. Unlike viscose dope, the cuprammonium cellulose [9050-09-3] solution is relatively stable. 

However, more accurate predictions for the spin velocity may be obtained with allowance made for the effect of viscosity in the governing equation for the spin velocity. According to the experimental data of Keisall," which indicates that the spin velocity in a cyclone is a function of R only, the A component of Eq. (13.1) in the cylindrical polar coordinate sy stem may reduce to... 

Over 22.7 million kg (50 million lb) of zinc sulfate are used annually in the U.S. for the manufacture of approximately 454 million kg (one billion lb) of viscose rayon. Zinc is used as a regeneration retardant in the acid spinning bath. Because it is not consumed in any of the viscose reactions, these 22.7 million kg (50 million lb) of zinc represent process losses, through dragout by the filaments to the subsequent wash streams, filter backwashing, splashes, leaks, and the washing of equipment.14... 

We are now going to compare the results of mode analysis with measurements of viscosity on polyethylene melts. With the aid of Eq. (30), which links the viscosity to the relaxation times, we can predict the viscosity using the results of spin-echo measurements and compare it with the viscosity measurement... 

Due to the disadvantage of comparatively poor migration resistance, P.R.5 is not used in plasticized PVC, but it can be applied in rigid PVC. Its lightfastness is excellent in this medium, transparent and opaque colorations (up to 0.01% pigment + 0.5% TiOz) equal step 7 and, respectively, step 6-7 on the Blue Scale. Dispersed pigment preparations are available for the mass coloration of viscose films as well as for spin dyeing of viscose rayon and viscose cellulose. 

P.R.89 affords a very bluish shade of red, referred to as pink. It exhibits good tinctorial strength and good lightfastness. Full shades in a combination nitro lacquer, for instance, equal step 7-8 on the Blue Scale. Somewhat poor overall fastness restricts the applicability of P.R.89. The pigment was considered a spe-cialpurpose product for artists colors. It used to be employed also in spin dyeing viscose products. 

Dichloroisoviolanthrone was supplied by the pigment industry in the form of a pigment preparation, which was a specialty product for use in spin dyed viscose fibers. This pigment preparation has only recently been withdrawn from the market. The shade of P.V.31 is a reddish violet, which is distinctly redder than that of the known... 

S. Sollinger and M. Voges, Simultaneous determination of the main constiments of viscose spinning solutions by visible near infrared spectroscopy, J. Near Infrared Spectrosc., 5, 135-148 (1997). 

This is the first reported study of the spinning of mesomorphic cellulose solutions, but no fiber properties were given. Quenin et al. (14) used a d -jet, wet spinning system to spin cellulose/MMNO-H20 solutions. Fiber properties equiv dent to the best viscose rayon fiber were obtained. 

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