| 摘要 |
In a process of bleaching cellulosic material with an alkaline hypochlorite solution, the concentration of active chlorine, as hypochlorite, in the bleaching bath is kept, by measurement of the electric potential of the bath, below that concentration above which the electric potential does not increase at an appreciable rate with increasing active chlorine concentration. The cellulosic material may be fibres, yarns or fabrics of cotton, linen or regenerated cellulose and may be previously treated with a hot sodium hydroxide solution. In examples the alkaline hypochlorite bath is at a temperature from 60 DEG to 80 DEG C. and initial active chlorine concentration of 0.023 to 0.05 grams per litre and successive additions of hypochlorite are made to maintain the concentration. The additions may be made automatically in response to changes in the electric potential. |
