Patent GB-864900-A (GB)
Title: Process for improving the optical properties of cellulose-containing materials
Filed: 1957-08-07
Abstract: A water-soluble compound capable of absorbing ultra violet light and having the formula: <FORM:0864900/IV (b)/1> is prepared by reacting <FORM:0864900/IV (b)/2> (prepared by coupling diazotised 1-amino-benzene-4-sulphonic acid with 1:3-diamine-benzene and oxidising the ortho-amino-azo-compound with ammoniacal copper sulphate to form the triazole) with cyanuric chloride in aqueous solution containing sodium carbamate, salting out with sodium chlorides, filtering, washing and drying.  Specifications 692,347 and 695,609 are referred to.ALSO:The optical properties of cellulose-containing materials, e.g natural cellulosic fibres, such as cotton and linen, regenerated cellulose fibres and films and half-wool, are improved by fixing thereon a water-soluble compound, capable of absorbing ultra-violet light and not having the character of a dyestuff, which contains at least one triazine ring substituted by two halogen atoms or one halogen atom and one hydroxyl group or one halogen atom and one alkoxy group containing up to three carbon atoms with the use of an agent capable of binding hydrogen halide, e.g. an alkali-metal hydroxide or carbonate.  The cellulose-containing materials are preferably pretreated in an aqueous medium containing at most 1% of the compound capable of absorbing ultra-violet light and a neutral salt, e.g. sodium chloride or sodium sulphate, at a temperature of 10 DEG -40 DEG C. for 10-40 minutes and are then treated in the same or in a different bath with the agent capable of binding hydrogen halide at 50 DEG -100 DEG C. Alternatively the materials may be treated with a solution containing at least 1% of the compound capable of absorbing ulta-violet light on a foulard, dried and then treated at 50 DEG -100 DEG C. with the agent capable of binding hydrogen halide. The compounds capable of absorbing ultra-violet light may contain carboxylic acid and/or sulphonic acid groups in the form of their water-soluble salts and an oxdiazole, imidazole, thiazole, oxazole or triazole ring.  Thus, there may be used compounds of the formula:-  <FORM:0864900/IV(c)/1> in which R1 represents an aryl residue, R2 represents an aryl residue fused on to the triazole ring, m and n are each 1 or 2 and at least one of the residues R1 and R2 contains a sulphonic acid group, or compounds in which one or two stilbene-2 : 21-disulphonic acid residues are bound to triazine rings through -NH- bridges, e.g. compounds of the formula:- <FORM:0864900/IV(c)/2> in which A is a substituted or unsubstituted amino group, k, m and n are each 1 or 2, p, q and r are each 1, 2 or 3 and p+q+r=5.  The process, which may be combined with dressing and water-proofing processes and with dyeing processes, using dyestuffs which are fixed on the materials under the conditions of the invention, may be used, not only for the optical brightening of cellulose-containing materials but also for protecting substances, e.g. foodstuffs, wrapped in cellulose-containing materials from the effects of ultra-violet rays.  Specifications 692,347 and 695,609 are referred to.