GB463056A - Improvements in or relating to the production of alkali cellulose particularly useful for making cellulose esters or ethers - Google Patents

Abstract

A process for the production of an alkali cellulose which is particularly suitable for the manufacture of esters or ethers comprises treating a cellulosic material containing esterifiable hydroxyl groups with metallic sodium in the presence of water and of an excess of liquid ammonia, the proportion of metallic sodium used being at least equivalent to the esterifiable hydroxyl groups of the cellulosic material, and at least sufficient to afford an alkali cellulose product which is substantially dry to the touch after removal of the ammonia by evaporation. The water present during the reaction may be added as such or introduced as hygroscopic moisture with the cellulosic material or ammonia. The cellulosic material may be an alkali cellulose prepared in the usual manner by treatment with aqueous caustic alkali, wood pulp, cotton linters, hydrocellulose, oxycellulose, or low substituted glycol cellulose, cellulose acetate, cellulose propionate, cellulose butyrate, or cellulose glycollic acid. In an example 81 parts of cellulose were steeped for one hour at 20 DEG C. in 40 per cent caustic soda, pressed to 374 parts, and shredded, 16,2 parts of this alkali cellulose were mixed with 100 parts of liquid ammonia containing 2,23 parts of metallic sodium. When the blue colour of the sodium had disappeared the majority of the ammonia was driven off, 100 parts of toluene added and the mixture heated to 100 DEG C. to drive off residual ammonia. The product had a molecular ratio of water to sodium hydroxide to cellulose of 8 : 11 : 1. It was especially suitable for making esters, e.g. the toluene suspension of alkali cellulose was cooled to 20 DEG C., 5.2 parts of p-toluene sulphonyl chloride added, the temperature being kept below 30 DEG C. at first and then raised to 100 DEG C. for 5 hours. The toluene was then poured off and the solid p-toluene sulphonate washed with ether, followed by water. The product contained 1,7 ester groups per C6H10O5. Its acetone solution gave a film or filament of good strength. In a second example 1000 parts of liquid ammonia, 135 parts of water and 178 parts of metallic sodium were added to 400 parts of cellulose. On disappearance of the blue colour of the sodium, ammonia was evaporated off, 10,000 parts of toluene added and the mixture heated to remove residual ammonia. In a third example no water was added, and 2000 parts of liquid ammonia and 26 parts of metallic sodium were added to 40 parts of cellulose. Subsequent procedure was as in the other examples. Specification 187,639, [Class 2 (ii)], is referred to.