Patent GB-409336-A (GB)
Title: Improvements in stripping dyeings prepared with vat dyestuffs
IPC: D06P5/13
Filed: 1932-10-22
Abstract: Protective colloids for addition to a dyestripping bath are inspissated sulphite waste liquor, glue, gelatine, soft roe, lysalbinic or protalbinic acid or the products of their reaction with stearic, oleic or other fatty acid chlorides, sericin, boiled-off soap, waxy polymerization products obtained from ethylene oxide, e.g. as described in Specification 346,550, [Group IV], and condensation products of ethylene oxide, an ethylene halohydrin, polyglycerol or an epihalohydrin with water-insoluble or difficulty soluble organic compounds containing at least six carbon atoms and at least one reactive hydrogen atom (cf. Specifications 368,530 and 380,431, [both in Group IV]).  Such organic compounds are, for example, (a) lauric, palmitic, oleic, linoleic, ricinoleic, montanic, naphthenic or abietic acid or mixtures of fatty acids contained in coconut oil or palm kernel oil, or fatty acids obtainable by blowing paraffin wax with oxygen-containing gases at about 160 DEG  C.; (b) the alkyl, hydroxy-alkyl or hydroxy-amino-alkyl esters or the amides of such acids; (c) the products of reaction of higher fatty acid chlorides with aminocarboxylic acids such as glycocoll or sarcosine; (d) alcohols containing at least ten carbon atoms, e.g. oleic or lauric alcohol or montanol; (e) alkylamines or their arylated derivatives, octadecylamine, oleylamine, hydroxyethyldodecylaniline or octadecyl--a --naphthylamine; (f) aromatic hydroxy compounds containing at least ten carbon atoms, e.g. b -naphthol; (g) aromatic amines, e.g. a -- or b -naphthylamine; (h) natural products of high molecular weight, such as casein, gelatine, glue, starch or cellulose.ALSO:The colour is stripped from vat-dyed textile materials by heating in an aqueous bath containing an alkaline reducing agent and adding a magnesium compound to the bath toward the end of the treatment.  Specified magnesium compounds are the sulphate, chloride, sulphide, nitrate, acetate and hydroxide.  Specified reducing agents are sodium and potassium hydrosulphites, sodium or zinc formaldehyde-sulphoxylates, glucose, and sodium sulphide.  A protective colloid is preferably present in the bath, such as inspissated sulphite waste liquor, glue, gelatine, soft roe, lysalbinic or protalbinic acid or the products of their reaction with stearic, oleic or other fatty acid chlorides, sericin, boiled-off soap, and condensation products of ethylene oxide, an ethylene halohydrin, polyglycerol or an epihalohydrin with water-insoluble or difficulty soluble organic compounds containing at least six carbon atoms and at least one reactive hydrogen atom (cf. Specifications 368,530 and 380,431).  Such organic compounds are, for example, (a) lauric, palmitic, oleic, linoleic, ricinoleic, montanic, naphthenic or abietic acid or mixtures of fatty acids contained in coconut oil or palm kernel oil, or fatty acids obtainable by blowing paraffin wax with oxygen-containing gases at about 160 DEG  C.; (b) the alkyl, hydroxyalkyl or hydroxy-amino-alkyl esters or the amides of such acids; (c) the products of reaction of higher fatty acid chlorides with aminocarboxylic acids such as glycocoll or sarcosine; (d) alcohols containing at least ten carbon atoms, e.g. oleic or lauric alcohol or montanol; (e) alkylamines or their arylated derivatives, e.g. octadecylamine, oleylamine, hydroxyethyl-dodecylaniline or octadecyl-a -naphthylamine; (f) aromatic hydroxy compounds containing at least ten carbon atoms, e.g. b -naphthol; (g) aromatic amines, e.g. a - or b -naphthylamine; (h) natural products of high molecular weight, such as casein, gelatine, glue, starch or cellulose.  Instead of or in addition to such protective colloids, waxy polymerisation products obtained from ethylene oxide, e.g. as described in Specification 346,550 may be employed to prevent the re-absorption of the vat dyestuffs by the fibre (cf. Specification 367,420).  The following examples are specified: (1) A cotton fabric, dyed with Indanthrene blue 5G is treated for \ba1/2\be hour in a boiling aqueous solution containing caustic soda and sodium hydrosulphite; magnesium sulphate is then added, the boiling is continued for \ba1/2\be hour, and the fabric is rinsed, preferably with water containing some sodium hydrosulphite, and dried.  (2) A cotton fabric, dyed with Indanthrene brilliant green B, is treated for \ba1/2\be hour in an aqueous solution at 90--95 DEG  C. containing caustic soda, sodium hydrosulphite and a product obtained, as described in example 1 of Specification 346,550, by polymerisation of ethylene oxide in presence of alkali; magnesium chloride is then added and the treatment is continued for \ba1/2\be hour; the stripping effect may be improved by a further treatment for \ba1/2\be hour in an aqueous solution at 95 DEG  C. containing the calcium salt of the sulphonic acid of dimethylphenyl-benzyl-ammonium sulphonic anhydride (cf. Example 3 of Specification 15722/10, [Class 2 (iii)]), caustic soda and sodium hydrosulphite.  (3) A fabric, dyed with Indanthrene brilliant violet RR, is treated for \ba1/2\be hour in an aqueous solution at 90--95 DEG  C. containing caustic soda, sodium hydrosulphite and a condensation product from ethylene oxide and octadecyl alcohol; magnesium sulphate is then added and the treatment is continued for \ba1/2\be hour; indigo dyeings on wool may be similarly stripped and artificial silk, dyed with Indanthrene blue RS may be stripped by treatment for \ba1/2\be hour in a similar solution at 60 DEG  C. with an addition of magnesium sulphate 10 minutes before the end.  (4) A fabric, dyed with Indanthrene blue RS, is treated for 1 hour in an aqueous solution at 90--95 DEG  C. containing caustic soda, sodium hydrosulphite and a condensation product from ethylene oxide and either oleyl alcohol or a coconut oil acid ethanolamide; magnesium sulphate is then added, the treatment is continued for \ba1/2\be hour, and the fabric is rinsed with water which may contain some hydrosulphite.  (5) A cotton fabric, dyed with Indanthrene brilliant green B, is treated for \ba1/2\be hour in an aqueous solution at 90 DEG  C. containing caustic soda, sodium hydrosulphite and a product obtainable by the action of ethylene oxide on casein as described in Specification 368,530; magnesium hydroxide is then added and the treatment is continued for \ba1/2\be hour.  (6) A calico fabric, dyed with Indanthrene yellow G, is treated for \ba1/2\be hour in an aqueous solution at 90 DEG  C. containing caustic soda, sodium sulphide and a condensation product from ethylene oxide and oleyl alcohol; magnesium sulphide is then added, the treatment is continued for \ba1/2\be hour and the fabric is rinsed with water which may contain some hydrosulphite. Hydroxyethyl-dodecyl-aniline is obtainable by condensation of hydroxyethyl-aniline with dodecyl bromide.  Octadecyl-a -naphthylamine is obtainable by condensation of a -naphthylamine with octadecyl bromide.