Patent GB-645392-A (GB)
Title: Improvements in or relating to the treatment of cellulose esters to improve their resistance to degradation by sunlight and ultra-violet light
IPC: D01F2/28
Filed: 1948-07-21
Abstract: The resistance of cellulose esters to degradation by sunlight and ultra-violet light is improved by incorporating in the cellulose ester an alkyl ester of gallic acid.  The proportion of the added substance may be 0.5 to 10 per cent based on the weight of the cellulose ester.  Ethyl, propyl, or lauryl gallate may be used.  An alkyl ester of gallic acid in which the hydroxyl groups are esterified with a lower aliphatic acid such as acetic acid or with an aromatic acid such as benzoic acid, may be used, e.g. triacetyl propyl gallate and tribenzoyl propyl gallate.  The alkyl gallates may be dissolved with the cellulose ester in a common solvent and the solution obtained may be spun into fibres or cast into films. Cellulose ester fibres, filaments, threads, fabrics, and films may be impregnated with a solution of the alkyl gallate in a solvent such as aqueous methylated spirit, or they may be treated with an aqueous dispersion of a tribenzoyl alkyl ester of gallic acid.  Dyed materials may be treated.  The cellulose ester may be cellulose acetate, propionate, butyrate, or aceto-butyrate. In an example, triacetyl propyl gallate is added to a solution of cellulose acetate in acetone and diacetone alcohol and the solution is cast and formed into a film.  In other examples, cellulose acetate fabric is impregnated with ethyl gallate solution, or with an aqueous dispersion of tribenzoyl propyl gallate made by stirring an acetone solution of the compound into water containing Turkey red oil.  In another example, triacetyl propyl gallate is added to a solution of cellulose acetate in aqueous acetone.  The solution is spun by a dry spinning method and the yarns obtained are dyed.  The resistance to degradation by sunlight persists after dyeing.  Specification 563,287 is referred to.ALSO:The resistance of cellulose ester fibres, filaments, threads, fabrics, or films, to degradation by sunlight and ultra-violet light is improved by impregnating them with a solution or dispersion of an alkyl ester of gallic acid, e.g. with a solution of an alkyl gallate in aqueous methylated spirit.  The proportion of the alkyl gallate incorporated in the cellulose ester materials may be 0.5 to 10 per cent based on the weight of the cellulose ester. Ethyl, propyl, or lauryl gallate may be used.  An alkyl ester of gallic acid in which the hydroxyl groups are esterified with a lower aliphatic acid such as acetic acid or with an aromatic acid such as benzoic acid, e.g. triacetyl propyl gallate or tri-benzoyl propyl gallate, may be used.  Tri-benzoyl alkyl esters of gallic acid may be employed in the form of aqueous dispersions.  Aqueous dispersions of tri-acetyl alkyl esters of gallic acid may be employed provided they are used immediately after being prepared.  Dyed materials may be treated.  In examples, cellulose acetate fabric is impregnated with ethyl gallate solution in methylated spirit and water mixture, or with an aqueous dispersion of tribenzoyl propyl gallate made by stirring an acetone solution of the compound into water containing Turkey red oil.  Specification 563,287 is referred to.