Patent GB-584436-A (GB)
Title: Improvements in the washing of textiles
IPC: C11D3/42
Filed: 1944-03-01
Abstract: White textile materials are washed in an aqueous bath containing a detergent and a very small proportion of a substantive blue fluorescent substance.  In an example white cotton and linen materials are washed in a soap liquor containing from about .00012 per cent. to .0024 per cent. of sodium 4 : 41- dipaminobenzoyl amino-stilbene -2 : 21- disulphonate based on the weight of the materials.  The Provisional Specification refers to soaps, soap products containing sodium carbonate, silicate or other soap adjuncts, non-soapy detergents, e.g., "Igepon" (Registered Trade Mark) and "Gardinol" (Registered Trade Mark) as suitable detergents. Specifications 442,530, [Group VIII], 522,672, [Group IV], and 584,484 are referred to.ALSO:White textile materials are washed in an aqueous bath containing a detergent and a very small proportion of a substantive blue-fluorescent substance.  Advantageously, the aqueous bath contains not more than one per cent and suitably between 0.01 per cent and 0.001 per cent of the blue-fluorescent substance calculated on the weight of the materials.  The blue-fluorescent substance is preferably one showing an absorption maximum at about 3400 to 3700 Angstrom.  Specified substances are: a di-benzoyl aminostilbene sulphonic acid or a nuclear substitution derivative thereof, or a salt of these acids.  In an example, white cotton and linen materials are washed in a soap liquor containing from about .00012 per cent to .0024 per cent of sodium 4 : 41-di-p-aminobenzoylaminostilbene-2 : 21-disulphonate based on the weight of the materials. Specified blue - fluorescent substances and selected methods of preparation are: a di-benzoylaminostilbene-sulphonic acid or a nuclear substitution derivative thereof or a salt of these acids, e.g. a 4 : 41-dibenzoylaminostilbene-2 : 21-disulphonic acid, 4 : 41 - di - p - aminobenzoylaminostilbene - 2 : 21 - disulphonic acid, sodium 4 : 41-di-p-methylbenzoylaminostilbene-2 : 21-disulphonate and the corresponding 3 : 31-disulphonates; these are prepared by the condensation of 4-nitrotoluene-3-sulphonic acid in the presence of alkaline sodium hypochlorite to form sodium 4 : 41-dinitrostilbene-3 : 31-disulphonate which may be reduced to sodium 4 : 41-diaminostilbene-3 : 31-disulphonate which may be treated with benzoyl chloride to form sodium 4 : 41 - di - benzoylaminostilbene - 3 : 31-disulphonate, or with p-nitrobenzoyl chloride followed by reduction to form sodium 4 : 41-di-p - aminobenzoyl - aminostilbene - 3 : 31 - disulphonate.  The corresponding 2 : 21-6 : 61-tetrasulphonates may be prepared similarly from 4 - nitrotoluene - 2 : 6 - disulphonic acid.  The symmetrical urea derived from sodium 4-amino-41-benzoylaminostilbene-2 : 21-disulphonate may be prepared by reducing 4 : 41-dinitrostilbene - 2 : 21 - disulphonic acid with sodium sulphide to form the nitro-amino compound which is then benzoylated, reduced and treated with phosgene.  Sodium 4 : 41-dibenzoyl - aminodibenzyl - 2 : 21 - disulphonate may be obtained by benzoylating 4 : 41-diaminobenzyl-2 : 21-disulphonic acid obtained by reducing 4 : 41-dinitrodibenzyl - 2 : 21-disulphonic acid derived from 4-nitrotoluene-2-sulphonic acid.  Benzidine derivatives such as sodium dibenzoyl-benzidine-3 : 31dicarboxylate and derivatives of benzthiazole such as 4-amino-1-phenyl-5-methylbenzthiazole may also be used as blue-fluorescent substances.  Specifications 442,530, [Group VIII], 522,672 and 584,484 are referred to.