GB347169A - Improvements in the production of nitro cellulose - Google Patents

Abstract

According to Specification 323,019, [Class 2 (ii), Cellulose &c.], wood pulp is partially gelatinized by treatment with caustic soda and carbon bisulphide, immersed in the form of strings or pellets in a hardening solution, washed, dried, and nitrated with a mixture in which normally the nitric acid exceeds the sulphuric acid. This method is now modified by nitrating the hardened and washed strings or pellets while they still contain a considerable amount of water, e.g. 10-20 per cent. A nitrating mixture containing less nitric acid than is recommended in the prior Specification, and in some instances an ordinary nitrating mixture, may then be used. The final washing of the hardened strings or pellets may be effected with warm water at a temperature of 50-70 DEG C. or with nitric acid. The material may be centrifuged before nitration. In an example, wood pulp is partially gelatinized by treatment with 10 per cent of caustic soda and 5 per cent of carbon bisulphide; if the wood pulp is preliminarily ground, 5-7 per cent of caustic soda and 2-3 per cent of carbon bisulphide may suffice. The product is then formed into strings or pellets, hardened in a bath containing 2 per cent of sulphurous acid, and washed, the final wash water being warmed. The product is then nitrated, while still containing 20 per cent of water, with a mixture containing nitric acid 37, sulphuric acid 57, and water 6 per cent.