GB547152A - Improvements in and relating to the manufacture of cellulosic film - Google Patents

Abstract

547,152. Films. BRITISH CELLOPHANE Ltd. Nov. 25, 1940, No. 16916. Convention date, Dec. 1, 1939. [Class 2 (ii)] In order to prevent or retard the formation of a deposit on the lips of the film-forming slot from which a cellulosic solution is extruded into an aqueous coagulating bath containing acid, there is added to the bath a small amount of a phenyl sulphonic acid substituted in the nucleus with an aliphatic radical containing 10-14 carbon atoms. Films of uniform thickness and appearance, free from streaks and scratches, can thus be obtained over long periods of working. The preferred sulphonic acids are those in which the aliphatic radical is in the para position. A mixture of sulphonic acids may be used. Instead of adding the free acid to the bath, the substance may be added in the form of its sodium or other salt. The proportion of the added substance may be 0.002 - 0.02 per cent. of the weight of the coagulating liquid. The process may be used in the production of films from aqueous, preferably alkaline, cellulosic solutions such as viscose, cuprammoniumcellulose solutions, and solutions of alkalisoluble, lowly-esterified or lowly-etherified cellulose. In an example, viscose is extruded through a slot into a solution of sulphuric acid and sodium sulphate containing a little p-decyl phenyl sulphonic acid or ptetradecyl phenyl sulphonic acid. In another example, the added substance is a mixture of alkyl substituted phenyl sulphonic acids in which the alkyl groups are straight chains of 10-14 carbon atoms or a mixture of alkyl substituted phenyl monosulphonic acids in which the alkyl groups have single branch chains and contain an average of 10 carbon atoms. The use of triisobutyl - phenyl mono-sulphonic acid is also specified. Specifications 211,446, [Class 2 (ii)], and 453,778 are referred to.