| 摘要 |
508,285. Viscose artificial threads. ALSA SOC. ANON. Dec. 5, 1938, No. 35429. Convention date, Dec. 14, 1937. [Class 2 (ii)] Artificial threads having hollow filaments are produced from a viscose containing sodium carbonate, 'any tendency for, the formation of an insoluble double carbonate of soda and lime being removed by incorporating in the viscose, prior to filtration, substances for precipitating the traces of lime introduced for example by the wood pulp. The precipitation of the lime may be effected by means of salts such as oxalates, secondary orthophosphates, metaphosphates, borates, hyposulphites, aluminates and their mixtures with silicates, or by means of soaps such as Marseilles soap or tallow soap. Instead of soap there may be used glycerides, or other esters of higher fatty acids, or these acids themselves, since these substances are converted into soap under the action of the alkali present in the viscose. The precipitant may be added at any point in the preparation of the viscose. Thus, it may be added to the alkali cellulose before xanthation, to the sodium carbonate solution which is incorporated in the viscose, or to the soda lye used in the dissolution of the xanthate. In an example,. stearic acid is incorporated in a viscose containing sodium carbonate, any calcium stearate formed being removed during the subsequent filtration. Specification 255,527, [Class 2 (ii)], is referred to. |
