GB1029838A - Improvements in and relating to viscose rayon filaments - Google Patents

Abstract

1,029,838. Modified viscose rayon. COURTAULDS Ltd. Sept. 18, 1962 [Sept. 19, 1961], No. 33449/61. Heading B5B. Modified viscose rayon is produced by wet spinning into an acidic coagulating and regenerating bath a viscose containing 10 to 40% of a protein such as casein based on the weight of the cellulose, and 10 to 40% of urea based on the weight of the protein, stretching the filaments and completing the regeneration of the cellulose component. In order to reduce the tendency for the polypeptide to be leached from the filaments in wet processing, the filaments are preferably impregnated with a cross-linking agent for one or more of the components of the filaments and the impregnated filaments are then preferably submitted to conditions causing the agent to react with one or more of the components. The cross-linking agent may be formaldehyde, an alkali metal cyanate or a zirconyl salt such as sodium zirconyl silicate. The viscose may be formed by mixing a protein, urea and alkali cellulose and xanthating the cellulose in known manner, or the protein and urea can be added to the ingredients of the viscose at any subsequent stage of the making of the viscose, including addition of protein and urea to the preformed viscose. As proteins are subject to degradation by caustic alkalis and viscose is alkaline, the protein and urea are preferably added to the viscose immediately before it is de-aerated on its way to an ageing tank or a spinning machine. In an example, 100 parts of a viscose containing 7À6% of cellulose and 6À2% of caustic soda are mixed with 1À52 parts of casein and 0À31 part urea, the mixture is agitated until the casein and urea have dissolved and is then filtered and deaerated. The solution is spun into a coagulating and regenerating bath containing 10% sulphuric acid, 20% sodium sulphate and 1À1% zinc sulphate. The filaments are taken from the bath, stretched by 60% of their original length before they are completely regenerated with hot dilute acid, washed and dried. The modified regenerated cellulose filaments of the invention are dyeable with acid dyes and have higher wet and dry strengths than prior art modified regenerated cellulose filaments.