GB398730A - Process for producing wood cellulose comparable to cotton, with high content of alkali resisting cellulose - Google Patents

Abstract

For the production of wood pulp with a high content of alkali-resisting cellulose, the material to be refined such as sulphite cellulose is treated in an autoclave with a liquid containing from 1-1,5 per cent of sodium hydrate and from 0,2-0,3 per cent of a colloidal emulsoid sodium salt, stable to alkali, at a pressure of 1-2 atmospheres and for a period of 1-2 hours. Sodium soaps of higher fatty acids may be used. The alkaline treatment removes hemicelluloses, fats, and resins. Complete removal of residual lignin components is effected by a mild oxidizing treatment which is carried out in two stages, first in a feebly alkaline and then in a feebly acid medium. The pulp, in a concentration of 5-6 per cent may be treated with a hypochlorite solution containing a small proportion of sodium carbonate, or calcium hydrate, or it may be treated with a dilute solution of sodium peroxide. The pulp may then be treated with a solution of hypochlorous acid or with a dilute solution of potassium permanganate containing a small proportion of sulphuric acid. The pulp is then treated with dilute sulphurous acid solution, washed and made into boards, sheets, felts, or flakes. If desired, the bleached material may be heated with dilute neutral sodium sulphite and a very small proportion of a colloidal sodium salt, and then washed, treated with sulphurous acid, and again washed. The product is similar to cotton cellulose in regard to its high content of alkali-resisting cellulose, its viscosity characteristics, and its hydrophilous power. It may be employed in the manufacture of cellulose esters and ethers and of artificial fibres and films.