GB611081A - Improvements in or relating to the production of alkali cellulose - Google Patents

Abstract

Alkali cellulose is prepared by a process in which the cellulose and alkali act upon each other in the presence of water, a liquid hydrocarbon such as benzene, toluene or xylene or a heterocyclic compound such as dioxan which is inert to both alkali and water, and methanol or ethanol. The alkali may be present from the commencement of the reaction in solid form, and the water added in any suitable way such as by conditioning the cellulose with steam. The cellulose may be from any source, natural or regenerated. If desired, wetting agents such as sodium isobutyrate, sodium lauryl sulphate, sulphonated castor oil, or the sodium salts of alkylated naphthalene sulphonic acids may be added at a pre-treatment stage or at any stage in the process. The process may be carried out if desired in the absence of air or oxygen, for instance in a reaction vessel filled with nitrogen, and at a temperature between 80 DEG and 190 DEG C., preferably within the range 110 DEG and 130 DEG C. In an example (all parts by weight) 20 parts of cellulose is conditioned with steam until its weight has increased four times. It is then introduced into an acid-proof autoclave and mixed with 40 parts sodium hydroxide (flakes or pastilles) 65 parts of benzene and 20 parts of ethyl alcohol. The contents are heated with stirring to 120 DEG -150 DEG C. for 2-10 hours. The Specification as open to inspection under Sect. 91 refers also to the production of alkali cellulose in the presence of propyl alcohol, and to the production of cellulose ethers, the reaction in this case taking place in the presence of an etherifying agent, water, the inert liquid hydrocarbon or heterocyclic compound and methyl, ethyl or propyl alcohol. Ethyl cellulose of ethoxy content higher than 42 to 47 per cent may be obtained by this method. The starting material may in addition be a cellulose derivative of low substitution, and it or the natural or regenerated cellulose may be pre-treated with formic, acetic, nitric or sulphuric acid. The etherifying agent may, if desired, be mixed according to the nature of the required product. The reaction may be carried out under a pressure of 5 to 25 atmospheres, preferably 12-15. In preparing the hither substituted ethers, the early part of the reaction is conveniently carried out at a higher temperature than the main part. This subject-matter does not appear in the Specification as accepted.