GB2255981A - Dry leuco sulphur dyes - Google Patents

Description

L. 2-) 59 '31 DRY LEUCO SULPHUR DYES For the dyeing of substrates (e.g.

cellulosic substrates) with sulphur dyes these are suitably applied in their leuco form, i.e. in the form of dyes conventionally known as leuco sulphur dyes. These leuco sulphur dyes can be produced by reducing the corresponding sulphur dyes with reducing agents, in particular with sodium sulphide or with reducing sugars, e.g. with glucose, as described e.g. in published U.K. Patent Application GB 2 201 165 A. Since in the reduction of sulphur dyes to give leuco sulphur dyes there are formed inorganic (poly)sulphides (mainly Na2S, Na2S2 and/or NaHS) and/or some sulphide in excess may be present, which constitute a disturbing component in the final product (as it may cause development of H2S when handling the dye or when dyeing with it, and/or results in the occurrance of inorganic sulphides in the back-water of the dyeings) it has been attempted to reduce as much as possible the inorganic sulphide content in the produced leuco sulphur dye and thus GB 2 201 165 A refers to a process for producing leuco sulphur dyes with a reduced sulphide content, in particular a sulphide content of about 1 to 14 X. However, even if the inorganic sulphide content can be as low as about 1 X, this may still constitute a source of H2S and may further increase on storage of the dye due to occasional decomposition by possible desulphurization of the oligosulphide bridges, which causes further formation of inorganic sulphide, which in turn is capable of producing the disturbing H2S. Further, if these dyes are purified to an inorganic sulphide content of less than 1 X, the dyes tend to oxidize in contact with air. This oxidation is favoured in the liquid form, so that on standing, in contact with air, there may be formed a disturbing film of oxidized product on the surface of liquid compositions of such dyes. Thus the liquid (in particular aqueous) forms of such dyes may oxidize resp. destabilize on storage rather soon, so as to discourage from commercializing them in this form or even from preparing in advance a stock solution to be stored and used as a stock for some time during dye- Case 150-5508 ing. For such dyes a minimum of about 2-3 % of inorganic sulphide is needed in order to substantially prevent oxidation as convenient for commercialization or even for storable stock solutions.

It has now been found that the amount of disturbing sulphide ions can be further reduced and a hydrosoluble leuco sulphur dye of high stability can be obtained, without having to use a reducing sulphide, if the sulphur dye is reduced in aqueous medium, in the presence of alkali metal hydroxide and preferably also of alkali metal (bi)sulphite, with a reducing carbonyl compound at high temperature, as indicated below, and the reaction mixture is directly dried, preferably at high temperature.

The invention relates to the new process, to the products of the process, to compositions containing said products and to the dyeing of substrates therewith.

The invention thus provides a process for the production of hydrosoluble dry leuco sulphur dyes (L) wherein a sulphur dye (S) is reacted in aqueous medium and at a temperature above 601C with an efficient amount of (A) a reducing carbonyl compound in the presence of (B) an alkali metal hydroxide, and dried.

According to a particular feature of the invention the reaction of (S) with 1 (A) is carried out also in the presence of an alkali metal sulphite and/or bisulphite. The invention thus provides also a process for the production of stabilized, hydrosoluble leuco sulphur dyes (L) wherein a sulphur dye (S) is reacted in aqueous medium at a temperature above 600C with an efficient amount of (A) in the presence of (B) and (C) an alkali metal sulphite and/or bisulphite and dried.

t Case 150-5508 As sulphur dyes (S) come in general into consideration conventional dyes known under this concept and as defined as "Sulphur Dyes" and 11Sulphurized Vat Dyes" in VENKATARAMAN "The Chemistry of Synthetic Dyes" Vol. II (Chapters XXXV and MVI) (1952) and Vol. VII (1974) or as defined e.g. in the "Colour Index" as "Sulphur Dyes" and also as 'Tat Dyes" with the further indication "sulphur", resp. with a structure number and a synthetic method involving a sulphurization. Essentially they are dyes that contain aromatically bound oligosulphide bridges that are reducible to thiol groups and may optionally be of oligomeric to polymeric structure. They are obtainable mainly by thionation of the respective intermediates at high temperature, e.g. above 1000C, in particular in the temperature range of 110-3001C (e.g. by baking or in the melt or in the presence of water and/or of an inert organic solvent).

The exact structure of sulphur dyes is mostly unknown or not completely known, even if the starting compounds are known, since e.g. the number and/or position of the oligosulphide bridges, the number of sulphur atoms in one oligosulphide bridge, the number of hetero rings and/or NH-bridges and/or the number of repeating monomeric units in the sulphur dye molecule may vary depending on the starting materials and synthetic conditions.

According to the invention there may be employed as (S) any sulphur dyes known to be reducible to corresponding leuco sulphur dyes, e.g. sulphur dyes and pre-reduced sulphur dyes known to lead to the following leuco sulphur dyes [Colour Index Leuco Sulphur denomination or Colour Index reduced Vat (sulphur) denomination]:

C.I. Leuco Sulphur Black 1, CAS: 66241-11-0 C.I. Leuco Sulphur Black 2, CAS: 101357-26-0 C.I. Leuco Sulphur Black 11, CAS: 90480-947 C.I. Leueo Sulphur Black 18, CAS: 90170-71-1 C.I. Leuco Sulphur Red 10, CAS: 1326-961 C.I. Leuco Sulphur Red 14, CAS: 68585-53-5 Leuco Sulphur Blue 3, CAS: 85566-77-4 Leuco Sulphur Blue 7, CAS: 69900-21-6 Leuco Sulphur Blue 11, CAS: 90480-94-7 Leuco Sulphur Blue 13, CAS: 12262-26-9 C. I. C. I. C. I. C. I.

C.I. Leuco Sulphur Blue 15, CAS: 100208-97-7 C.I. Leuco Sulphur Blue 20, CAS: 85940-25-6 C.I. Reduced Vat Blue 43, CAS: 132779-3 C.I. Leuco Sulphur Green 2, CAS: 12262-32-7 C.I. Leuco Sulphur Green 16, CAS: 70892-38-5 C.I. Leuco Sulphur Green 35, CAS: 90170-23-3 C.I. Leuco Sulphur Green 36, CAS: 90295-17-3 C.I. Leuco Sulphur Brown 1, CAS: 1326-37-0 C.I. Leuco Sulphur Brown 3, CAS: 100208-66-0 C.I. Leuco Sulphur Brown 10, CAS: 12262-27-0 C.I. Leuco Sulphur Brown 21, CAS: 97467-78-2 C.I. Leuco Sulphur Brown 26, CAS: 71838-68-1 C.I. Leuco Sulphur Brown 31, CAS: 1327- 11-3 C.I. Leuco Sulphur Brown 37, CAS: 70892-34-1 C.I. Leuco Sulphur Brown 52, CAS: 68511-02-4 C.I. Leuco Sulphur Brown 95, C.I. C.I. C.I. C.I.

Leuco Leuco Leuco Leuco Sulphur Sulphur Sulphur Sulphur Brown 96, Orange 1, CAS: Yellow 9, CAS: Yellow 22, CAS CAS: CAS:

90268-97-6 85736-99-8 1326-49-4 85737-01-5 90268-98-7 Case 150-5508 - in particular the respective C.I. Sulphur Dyes or C.I. Vat (sulphur) Dyes (respectively the corresponding starting materials, when the synthesis of the sulphur dye and its reduction according to the invention are carried out in one reaction sequence) and which by the process of the invention lead to the corresponding stabilized leuco form.

The sulphur dyes (S) are preferably employed in the form of an aqueous (S)-containing mass (P), in particular of an aqueous paste. The aqueous mass (P) may be produced e.g. by suspending in water a commercial sulphur dye or a sulphur dye produced by baking or in the melt, or preferably the aqueous mass (P) is the aqueous reaction mixture of the production of the sulphur dye in the presence of water or, according to a particularly preferred feature of the invention, an aqueous filter cake resulting from the filtration of an aqueous thionation reaction mixture, which thionation reaction mixture may previously have been precipitated e.g. by oxidation and/or acidification; or, according to a further particular feature of the invention, (P) is a reaction mixture obtained from the reaction steps of thionation, Case 150-5508 reduction with sulphide and re-precipitation of the dye by oxidation (e.g. with air), or a filter cake resulting from the filtration of such a reaction mixture.

The reducing agent (A) is preferably aliphatic and is suitably a carbonyl compound that contains in ot-position to the carbonyl group a donor as a substituent; preferably the substituent in ot-position to the carbonyl group is a hydroxy group, optionally etherified, in particular a methoxy group, or an amino group which may optionally be acetylated. As (A) come principally into consideration aliphatic compounds with 3 to 6 carbon atoms, in particular 1-hydroxyacetone, carbohydrates with 3 to 6 carbon atoms and their derivatives in which one or more of the present hydroxy groups are etherified with methyl or replaced by an amino or acetylamino group, in particular a1do sugars and keto sugars and their oligomers and/or desoxy-derivatives and further their uronic acids. Preferred carbonyl compounds (A) may be represented by the following formulae 1 " R, ' I I -CHO M I R2, n R, ' R2 (n-1 wherein the one of R, and R2 signifies hydrogen and the other signifies - OHY -OCH3 or -NH29 R3 signifies -CH3, -CH20Ht -CHO or -COOM, M signifies hydrogen or a cation and n signifies an integer from 1 to 5.

(11) 1 M is advantageously a colourless cation, preferably an alkali metal cation, more preferably sodium.

If in formula (I) n is an integer from 2 to 5 the n symbols R, may have, independently, the same significance or different significances and the n symbols R2 may have, independently, the same significance or different significances. In formula (I) one of R, and R2 is hydrogen and the other preferably is hydroxy; R3 in formula (I) preferably signifies -CH20H, or if n signifies 2 to 5, also a carboxy group; n in formula (I) preferably signifies 3 or more preferably 4. If in formula (II) n signifies 3, 4 or 5 the (n-1) symbols R, may, independently from each other, have the same signifi- Case 150-5508 cance or different significances and the (n-1) symbols R2 may, independently from each other, have the same significance or different significances. In formula (II) one of the two symbols R, and R2 signifies hydrogen and the other preferably signifies hydroxy. If in formula (II) n signifies 1, R3 preferably signifies -CH3 or -CH20H; if in formula (II) n signifies 2, 3, 4 or 5, R3 preferably signifies -CH20H. Of the compounds of formula (II) are preferred those in which n signifies 1, 3 or 4. The monosaccharides of formula (I) and of formula (II) may also be in the pyranoside or furanoside form; the uronic acids of formula (I) and of formula (II) may also be in the lactone form.

Representative reducing sugars are, in particular, aldopentoses, especially arabinose, ribose and xylose, and hexoses, especially glucose, fructose, mannose and galactose, and their desoxy, disdesoxy and aminodesoxy derivatives. As (A) there may also be employed oligosaccharides, in particular disaccharides, especially sucrose, lactose, maltose, melibiose and cellobiose, and tri-, tetra- and pentasaccharides, especially melezitose and raffinose, and further sirups, such as corn sirup, malt sirup and molasses, which contain reducing sugars. The preferred reducing sugar is glucose.

Suitably the quantity of (A) is chosen so as to suffice for the practically complete reduction of the employed sulphur dye (S). The required quantity of (A) and also the preferred quantity of (A) may vary depending on the sulphur dye, the synthetic method used for its production and the chosen compound (A). Advantageously (A) is employed in amounts of 1 to 40, preferably 5 to 15 % by weight referred to the dry final product (L). Expressed with reference to the weight of active material, which here is the total amount of polymeric products obtained in the production of the sulphur dye (S), (A) is advantageously employed in amounts in the range of 1 to 80, preferably 5 to 40, more preferably 10 to 20 % by weight. The suitable or, in particular, preferred quantity of (A) may be determined by means of a few preliminary tests.

As (B) there may be employed dry or preferably aqueous alkali metal hydroxide, in particular aqueous lithium hydroxide, sodium hydroxide or potassium hydroxide solutions, preferably sodium hydroxide solutions or potassium hydroxide solutions. (B) may be employed in the form of conventional aqueous solutions, in particular of a concentration of > 10 % by weight, Case 150-5508 preferably k 20 % by weight, advantageously of higher concentration, in order to keep the quantity of water to be evaporated and also the evaporation time to a minimum. Preferably (B) is employed in the form of aqueous 30 to 50 % alkali metal hydroxide, in particular sodium hydroxide or potassium hydroxide. The reacted amount of (B) may vary not only with (S) but also with (A) and (C) and their relative quantities. The amount and concentration of alkali metal hydroxide is suitably chosen so that an excess of alkali metal hydroxide, i.e. some unreacted alkali metal hydroxide (B), is present in the dry final product (L), advantageously an excess of 0.5 to 20 % by weight, preferably 3 to 10 % by weight, referred to the weight of the dry final product (L). Expressed with reference to the weight of active material (as defined above) the excess amount of (B) advantageously is in the range of 1 to 40, preferably 5 to 20 % by weight. The concentration of (B) in the reaction mixture is suitably so that the pH is above 12, pre ferably above 14. With particular preference the alkali metal hydroxide concentration in the reaction medium is such that it is present as a 1N to 12N solution, preferably 2.5N to 8N solution, with reference to the total of water present in the reaction mixture. In the aqueous concentrated alkali metal hydroxide solution the reducing sugars may form the so-called reductones.

As (C) there may be employed lithium, sodium or potassium sulphite or bisulphite or a mixture of two or more thereof, preferably sodium sulphite and/or most preferably sodium bisulphite. (C) is advantageously employed in amounts of 1 to 40, preferably 2 to 24, more preferably 5 to 10 % by weight, referred to the weight of the dry stabilized product (L). Expressed with reference to the weight of active material (as defined above) (C) is advantageously employed in amounts in the range of 1 to 80, preferably 5 to 40, more preferably 10 to 20 % by weight.

The weight ratio of (A)/(C) may vary broadly, in particular in the range of 1/10 to 10/1, advantageously 1/5 to 5/1, preferably 2/1 to 1/2, more preferably 1/1.5 to 1.5/1.

The total water content of the reaction mixture at the beginning of the reaction is conveniently at least such that the mixture is easily stirrable and the aqueous phase represents the continuous phase and is advantageously < 95 % by weight, preferably 8 % by weight; it may vary depending on the Case 150-5508 employed reactants. Advantageously the water content of the reaction mixture at the beginning of the reaction is at least 10 % by weight, in particular 10 to 90 % by weight, preferably 20 to 80 % by weight.

The water content of (P) may vary in a broad range, depending on its pro duction, and may suitably be in the range of 5 to 95 % by weight, preferably 10 to 90 % by weight, referred to the total of (P). If (P) is a reaction mixture resulting from the thionation reaction in aqueous medium (and, depending on the dye, optionally precipitation by acidification and/or oxidation) for the production of the sulphur dye (S), it may be employed as such or may previously be filtered, the choice depending mainly on the water content, inorganic sulphides content andlor further salt content of the dye suspension, secondarily also on its filterability and further also on the concentration of the dried dye aimed at. Reaction mixtures with a water content > 95 % by weight or even > 90 % by weight are preferably subjected to filtration (if desired or if required in the presence of a filter aid). By filtration the water content may be substantially reduced and may range e.g. in the scope of 8 to 90 % by weight in the filter cake, depending on the consistence of the suspended dye, on the filter system and on the presence of any filter aid. Preferably the water content of (P) is in the range of 20 to 80 % by weight.

The reduction reaction is carried out at temperatures above 60% advantageously in the temperature range of 65 to 2000C, preferably 95 to 190% if required under superatmospheric pressure, particularly in the temperature range of 100 to 140C especially for long time reactions (i.e. of > 1 hour, in particular 2 to 30 hours, optionally with at least partially simultaneous drying as described below) and higher temperature ranges, particularly 130 to 190% more preferably 145 to 190% for short time reactions as described below, especially with at least partially simultaneous drying (i.e. < 1 hour, in particular 2 to 30 minutes resp. 4 to 30 minutes).

The reaction may be carried out with exclusion of oxygen, in particular of air, e.g. under a nitrogen blanket, or preferably without the exclusion of air. The reaction is suitably continued until reduction to the corresponding leuco form is practically complete, i.e. until the obtained reduction product is readily and completely soluble in water, with practically no insoluble non-reduced sulphur-dye residue - this can be assessed by a simple Case 150-5508 hydrosolubility test, e.g. by dissolving 5 g of reduction product in 95 g of demineralized water at room temperature (= 201C) with stirring until the soluble product is completely dissolved to a 5 X solution and then filtering through a paper filter "Schleicher & SchUll" 589/2. A completely soluble product leaves no undissolved particles on the filter. That reduction is practically complete and the reduced product is readily soluble in water signifies that most or practically all of the oligosulphide bridges in the sulphur dye (in particular at least 95 %, preferably 99 to 100 %) are reduced. The process of the invention may be carried out in two stages, i.e. first the reduction reaction to obtain an aqueous akaline leuco sulphur dye solution and then the drying of the obtained solution, or preferably in one stage, i.e. the reduction reaction and the evaporation of the water (drying) are carried out simultaneously or in part simultaneously (i.e. the reduction reaction is completed during the drying). Similarly as the reduction reaction the drying may be carried out in the presence or in the absence of air, e.g. under a nitrogen blanket. Where the process is carried out in two stages, preferably at least one of the two stages, reduction reaction and drying, is carried out in the presence of air; most preferably as well the reduction reaction as the drying are carried out in the presence of air. The reaction time may vary broadly depending on the employed apparatus, the composition of the reaction mixture and the reaction parameters; it may range in particular in the scope of 2 minutes to 30 hours, preferably 4 minutes to 12 hours.

Drying is preferably carried out also at temperatures above 60C, in particular at temperatures in the range of 65 to 2000C, advantageously 95 to 190C, more preferably 100 to 1400C in particular for long time drying (i.e. > 1 hour, especially 2 to 30 hours), respectively 130 to 1900C, preferably 145 to 1900C for short time drying (i.e. < I hour, especially 2 minutes to 30 minutes). According to a particularly practical feature the reaction mixture is dried practically at the same temperature at which the reaction has been carried out 20, preferably 10. The drying can be carried out by means of conventional drying systems and apparatuses (in particular evaporators), e.g. by spray-drying or film-drying (e.g. on conveyor belts - heated e.g. with infrared radiation, microwaves or other systems - or on drying drums - heated e.g. with steam or fitted with a heated jacket), and the dried product may if desired be further comminuted to the desired particle size, to give the dry reduced hydrosoluble product e.g. in - the form of granules, powder or scales.

Case 150-5508 Where, according to the preferred feature, the reaction is carried out at least in part simultaneously with the evaporation (drying) of the aqueous mixture the total time required therefor will depend on the employed drying system, the employed temperature, the consistency of the mass and its depth and may vary broadly, e.g. in the range of 4 minutes to 30 hours, preferably 5 minutes to 12 hours. Thus with continuous systems such as film drying on conveyor belts or drying drums or by spray drying, the drying time, and in particular even the whole time required for the process of the invention, may be as low as 4 to 30 minutes, preferably in the range of 5 to 20 minutes. Preferably the reaction mixture is directly dried so that the reduction reaction takes place during the evaporation of the water to directly obtain in one process step the reduced and dried product.

As a dry product, in particular as a dry product (L), there is meant a solid leuco sulphur dye as obtainable by a drying procedure as described, especially with a water content < 5 % by weight, preferably 2 % by weight of the product.

By the described process it is possible to obtain in a very simple way and without the addition of other reactants (in particular in the absence of any added sulphide) and assistants (in particular in the absence of any surfactants) stabilized leuco sulphur dyes (L) of high concentration which are practically free of sulphide ions, in particular in which the inorganic sulphide content of the dry product is below 1 % by weight, more particularly even below 0.2 % by weight, it being possible to obtain products that are free of inorganic sulphides (as detectable by normal analytical methods with a sensitivity of 0.01 X) and which in the presence of acids do not develop any organoleptically perceivable H2S. Further the obtained dyes (L) have a notable stability against atmospheric oxidation in their solid form or also in liquid form, in particular also in the form of aqueous stock solutions (as are usually prepared before dyeing).

The obtained dried leuco sulphur dyes (L) are readily hydrosoluble and can be formulated to liquid, in particular aqueous, compositions by plain dilution with water, there being obtainable aqueous solutions even of high concentration, in particular of a concentration of > 5 % by weight of (L) up Case 150-5508 to the saturation concentration. For the formulation of concentrated compositions, e.g. containing 5 to 50, preferably 10 to 40 % by weight of (L), it may also be of advantage to add formulation additions, in particular solubilizers and/or hydrotropics, e.g. urea, mono-, di- or triethylene glycol Cl-4-alkylmonoether, mono-, di- or tripropylene glycol Cl-4-alkylmonoether, mono-, di- or triethanolamine or mono-, di- or triisopropanolamine, and/or anionic surfactants, e.g. sulpho group- containing surfactants with 6 to 24 carbon atoms in the lipophilic radicals (e.g. sodium xylenesulphonate, lignin sulphonate or dinaphthylmethane disulphonate), and/or reduction stabilizers (which may e.g. be selected among conventional sulphide-free redox products, such as thiourea dioxide).

Such liquid compositions - in particular those of products (L) obtained in the presence of (C) - are very stable and their tendency to form by air-oxidation a disturbing surface film, even when they are diluted with water to stock solutions before dyeing, is also substantially reduced, so that the liquid concentrated compositions can be shipped and/or stored for several days or weeks without any disturbing alteration of the composition and the stock solutions can be prepared and stored as suitable before dyeing, without any disturbing alteration, in particular without formation of a disturbing oxidation film on the surface of the solution.

The obtained stabilized leuco sulphur dyes (L) may presumably be regarded as (hemi)mercaptals of the reducing carbonyl compounds (A) (or of corresponding reductones), i.e. as leucosulphur dyes in which at least some of the thiol or thiolate groups have reacted with the reducing carbonyl group to give a corresponding (hemi)mercaptal, which is stabilized during the drying process rendering the dye stable to air oxidation and to inner dismutation.

The products (L) obtainable by means of the process of the invention are hydrosoluble dyes of low affinity and are suitable for the dyeing of textile or non-textile substrates dyeable with sulphur dyes; those obtained in the presence of (C) excell by their particularly good hydrosolubility and stability also in pre-diluted form (in particular as stock-solutions), those obtained in the absence of (C) are particularly suitable also for the dyeing of paper. They are suitably applied on the substrate in their leuco-form and then e.g. oxidized on the substrate to give the corresponding - 12 Case 150-5508 oxidized form (which process is particularly suitable for the dyeing of cellulosic textile material) or fixed in another way, e.g. by precipitation on the substrate (especially when sizing the substrate) resp. bonding to the size which is fixed to the substrate - in particular for sized textiles, bonded non-wovens or sized paper.

As materials dyeable with the dyes of the invention from aqueous medium with subsequent oxidation or other fixation of the dye there may be mentioned in particular fibrous materials, principally cellulosic material and natural or synthetic polyamides (e.g. wool, leather, synthetic polyamides). The fibrous substrate may be in any form as conventionally employed for dyeing, e.g. as loose fibres, filaments, yarns, skeins, hanks, bobbins, non-wovens, felts, woven or knitted goods, carpets, velvets, tuftings as well as half ready-made or ready-made goods. The dye may be applied by any method conventional per se in the art, e.g. by exhaust methods (from short or long liquors, e.g. at liquor-to-goods ratios in the range of 2:1 to 120:1, preferably 10:1 to 40:1) or by impregnation methods (e.g. by padding, dipping, spraying, foam application or printing). The dye-liquors may also contain additives in particular as conventional in the art, e.g. wetting agents, levelling agents, metal-sequestering agents, build-up adjuvants, reducing agents and/or further additives deriving e.g. from the use of the dyes in the form of a liquid formulation in particular as described above. Advantageously the dye-liquor contains a sulphide-free reducing agent, e. g. formaldehyde sulphoxylate, thiourea dioxide, sodium or potassium hydrosulphite or a carbonyl compound preferably as defined above for (A), in particular hydroxyacetone or a reducing mono- or oligosaccharide, preferably glucose; the reducing compound is present in the dyeing liquor advantageously in a concentration of 5 to 100, preferably 10 to 80 % by weight, referred to the dye. For the impregnation the liquor may, if desired, further contain a thickening agent.

Exhaust dyeing may take place at conventional temperatures, on textile material in particular in the range of 60 to 140C, if required under superatmospheric pressure, on cellulosic textile material and/or on synthetic polyamide textile material advantageously at temperatures in the range of 90 to 135C, e.g under HT-conditions (preferably 102 to 1300C) or preferably at 90C to the boil, in particular at 950C to the boil, and under neutral to basic pH-conditions (preferably pH > 7.5, more preferably 12, Case 150-5508 e.g. at pH 12 to 14), preferably with addition of a reducing agent as in dicated above and suitably together with the adequate quantity of alkali metal hydroxide, particularly NaOH, and advantageously an inorganic hydrosoluble salt as conventionally employed in exhaust dyeing, e.g. sodium chloride, sodium sulphate or sodium carbonate, in order to favour build-up.

For impregnation the impregnation liquors may be of an analogous composition as the exhaust dyeing liquors and in a concentration as suitable for the selected application and may further contain additives as suitable for the respective impregnation method, e.g. thickeners. The impregnated goods may be fixed by conventional means e.g. by heating,preferably to temperatures > 100% e.g. with dry heat, e.g. at 130 to 180% or preferably by steaming, e.g. at 100 to 1WC.

The dyeing is expediently concluded by fixation of the dye, mainly by oxidation or in another way. Oxidation may be carried out with conventional oxidizing agents, e.g. with air, oxygen, peroxides or oxidizing halogen compounds (e.g. alkali metal bromates, iodates, chlorates or chlorites), at pH conditions in the range from acidic to alkaline, preferably at a pH in the range of 4 to 8, in particular 4.5-7. 5 when oxidizing with halogenates, peroxides, oxygen or air, or under alkaline conditions, in particular at a pH in the range of 8 to 11, more preferably 9 to 10.5 when oxidizing with an alkali metal halogenite, especially sodium chlorite. Peroxides, in particular H202, may also be employed under alkaline conditions. Since tap water or (partially) demineralized water as conventionally employed in dyeing plants contains some dissolved oxygen, oxidation may also be achieved by rinsing with correspondingly large amounts of water.

The fixation of the dye in another way than by oxidation may take place e. g. by precipitation with or bonding to a suitable agent employed as a fixing agent or finishing resin e.g. on textiles or non-wovens, or as a flocculating, de-watering or retention agent and/or as a size in paper production, in particular calcium or aluminium salts - preferably aluminium sulphate - (which is particularly suitable for the dyeing of paper).

Paper is suitably dyed in the mass, preferably in the form of aqueous paper stuff supension, advantageously at temperatures in the range of 15 to 40C (the simplest at ambient temperature) and preferably at pH values in the Case 150-5508 range of 8 to 11 [in particular as may result by dissolving an alkali metal hydroxide-containing dye (L) or a stock solution thereof in the liquor]. The dye may then be precipitated on the fibre or bonded e-g to a size by addition of a suitable size and/or a de-watering or retention agent, preferably under weakly acidic conditions, in particular at a pH in the range of 4.5 to 6.5.

There are obtainable dyeings of optimum yield and fastnesses. During the dyeing the soiling of the dyeing-machines is reduced to a minimum. With the use of the leuco sulphur dyes (L) of the invention a disturbing hydrogen sulphide development and/or a disturbing inorganic sulphide occurrance in the waste water of the dyeing may efficiently be avoided.

In the following examples the percentages are by weight and the temperatures are in degrees Celsius. The hydrosolubility of the products is tested by the following method: Prepare 100 ml of a 5 % solution of the reduction product in demineralized water at 200C, stirring until the product is completely dissolved (which takes about 5 minutes), and filter by means of suction through a paper filter Schleicher & SchOll 589/2 of 7 cm of diameter; filtration of a readily and completely dissolved product takes place in a few seconds and leaves no undissolved residue on the filter.

The sulphide content of the product may be determined by acidifying 100 ml of a 1 % w/w solution of the product in distilled water placed in a first vessel with 2 ml of 80 % acetic acid, collecting any developped H2S with the aid of a C02 or N2 stream, passed through the solution placed in the first vessel, into one or more further vessels that contain a liquid suitable for binding the H2S (e.g. an aqueous metal oxide or hydroxide or heavy metal salt solution) in which the sulphide may then be analyzed in conventional way.

Example 1 a) 200 g of 2,4-dinitrochlorobenzene are reacted with 169 g of an aqueous 50 % sodium hydroxide solution at 1000C for 2 hours. The obtained product is added into a mixture of a solution of 200 g of sodium sulphide in 200 g of water and 127 g of sulphur and the mixture is heated to 116-120C and refluxed at this temperature for 10-15 hours after which is - Case 150-5508 the mixture is diluted with 200 g of water and aerated by passing air through the solution until the dye is precipitated. The obtained mixture is then filtered and washed with water to give a filter cake of black dye with a water content of 40-60 X.

b) This filter cake is mixed in a 1 1 evaporating pan with 100 g of aqueous 50 % sodium hydroxide solution and 26 g of glucose. This mixture is heated to 120-1301C and maintained for 12 hours at 120-130C until the mixture is dry. There are obtained 260 g of dry black product (1) readily and completely soluble in water, is free of inorganic sulphides and is stable to air oxidation even in the form of a 1 % aqueous solution of the product.

Example 2 a) 200 g of 2,4-dinitrochlorobenzene are reacted with 169 g of an aqueous 50 % sodium hydroxide solution at 1001C for 2 hours. The obtained product is added into a mixture of a solution of 200 g of sodium sulphide in 200 g of water and 127 g of sulphur and the mixture is heated to 116-1201C and refluxed at this temperature for 10-15 hours.

b) 100 g of 50 % sodium hydroxide solution and 35 g of glucose are then added and the obtained mixture is reacted and dried at 120-1300C in a 1 1 evaporating pan during 12 hours. There are obtained 590 g of a dry black powder (2), which is readily and completely soluble in water and the sodium sulphide content of which is < 0.1 X.

Examples 3 and 4 The process according to Example 1 resp. according to Example 2 is repeated, with the difference that the 2,4-dinitrochlorobenzene is replaced by a mixture of equimolar proportions of picric acid and 2,4- dinitrochlorobenzene. The obtained dry products (3) resp. (4) are readily and completely soluble in water.

Examples This to 4bis The processes according to Examples 1, 2, 3 resp. 4 are repeatedt with the Case 150-5508 difference that the glucose is replaced by the equivalent amount of maltose. The obtained dry products (1a), (2a), (3a) resp. (4a) are readily and completely soluble in water.

Examples lter to 4ter The processes according to Examples 1, 2, 3 resp. 4 are repeated, with the difference that the glucose is replaced by the equivalent amount of lactose. The obtained dry products (1b), (2b), (3b) resp. (4b) are readily and completely soluble in water.

Examples lquater to 4quater The processes according to Examples 1, 2, 3 resp. 4 are repeated, with the difference that the glucose is replaced by the equivalent amount of xylose. The obtained dry products (1c), (2c), (3c) resp. (4c) are readily and completely soluble in water.

Example 5 a) 200 g of the thionation reaction product obtained by reaction of sodium polysulphide and sulphonated copper phthalocyanine (4 sulpho groups) is diluted with water and oxidized with air until the dye precipitates. The mixture is neutralized with sulphuric acid to a pH of 7, then vacuum filtered and washed with water. There are obtained 560 g of filter cake of a green dye with a water content of 80-85 X.

b) 250 g of this filter cake are mixed in a 1 1 evaporating pan with 120 g of water, 34 g of aqueous 50 % sodium hydroxide and 13.5 g of glucose and the mixture is heated to 100C and maintained at this temperature for 10 hours. There are obtained 60 g of a green dye powder (5) in reduced form, which contains 5 % NaOH referred to the weight of the final dry product, is free of inorganic sulphides, is readily and completely soluble in water and dyes cotton in intense green shades, when applied in the presence of suitable reducing agents (e.g. glucose) and sodium hydroxide and with subsequent oxidation.

1 Example 6

Case 150-5508 a) A mixture of 45 g of sulphur, 54 g of sodium sulphide 60 % and 45 g of 2,4-diaminotoluene is baked in a rotary drum at 280C during 24 hours. The obtained solid product is dissolved in 500 g of water and 20 g of NaOH at 100C during 3 hours. The obtained mixture is diluted with 500 g of water and air is passed through the solution until the sulphide is oxidized and the dye is precipitated. The pH is then adjusted to 7 by addition of sulphuric acid, the obtained mixture is vacuum filtered and the presscake is washed with water.

b) The obtained filter cake (with a water content of 75-85 X) is admixed with 50 g of aqueous 50 % sodium hydroxide, 18 g of glucose and 50 g of water. Then the mixture is reacted and dried simultaneously at 120-1300C in an evaporating pan during 10 hours. There are obtained 110 g of dry leuco sulphur brown (6) which is readily and completely soluble in water and that, suitably applied in the presence of a reducing agent as indicated above (e.g. glucose) and of NaOH and then oxidized, gives dyeings of deep yellowish brown shades on cotton.

Example 7

250 g of the filter cake obtained according to Example 1 part a) are mixed with 66 g of aqueous 50 % sodium hydroxide and 16 g of glucose. 20 g of this mixture are put in the form of a thin layer into an evaporating pan, heated to 1651C and dried within 8 minutes. There are obtained 7 g of dry black product (7) readily and completely soluble in water, is free of inorganic sulphides and is stable to air oxidation even in the form of a 1 % aqueous solution of the product.

The respective filter cakes of Examples 5 a) and 6 a) and the refluxed mix- ture of Example 2 a) can be reduced and dried in an analogous way as described in Example 7 for the filter cake of Example 1 a).

Example 8

The filter cake obtained according to Example 1 part a) is mixed in a 1 1 evaporating pan with 120 g of aqueous 50 % sodium hydroxide solution, 28 g Case 150-5508 of glucose and 28 g of sodium bisulphite. This mixture is heated to 120- 1401C and maintained for 8 hours at 120-140C until the mixture is dry. There are obtained 300 g of a black solid reduced product (8) which is readily and completely soluble in water, is free of inorganic sulphides and is stable to air oxidation even in the form of a 1 % aqueous solution of the product.

Example 9 g of 50 % sodium hydroxide, 35 g of glucose and 25 g of sodium bisulphite are added to the product obtained according to Example 2 part a) and the obtained mixture is reacted and dried at 120-130C in a 1 1 evaporating pan during 12 hours. There are obtained 626 g of a dry black powder (9), which is readily and completely soluble in water and the sodium sulphide content of which is < 0.1 X.

Examples 10 and 11 The processes according to Example 8 resp. according to Example 9 are repeated, with the difference that the 2,4-dinitrochlorobenzene is replaced by a mixture of equimolar proportions of picric acid and 2,4- dinitrochlorobenzene. The obtained dry products (10) resp. (11) are readily and completely soluble in water.

Examples 8bis to 11bis The processes according to Examples 8, 9, 10 and 11 are repeated, with the difference that the glucose is replaced by the equivalent amount of maltose. The obtained dry products (8a), (9a), (10a) resp. (11a) are readily and completely soluble in water.

Examples 8ter to 11ter The processes according to Examples 8, 9, 10 and 11 are repeated, with the difference that the glucose is replaced by the equivalent amount of lactose. The obtained dry products (8b), (9b), (10b) resp. (11b) are readily and completely soluble in water.

19 - Examples 8quater to 11quater Case 150-5508 The processes according to Examples 8, 9, 10 and 11 are repeated, with the difference that the glucose is replaced by the equivalent amount of xylose. The obtained dry products (8c), (9c), (10c) resp. (11c) are readily and completely soluble in water.

Example 12

250 g of the filter cake obtained according to Example 5 part a) are mixed in a 1 1 evaporating pan with 120 g of water, 44 g of aqueous 50 % sodium hydroxide, 13.5 g of sodium bisulphite and 13.5 g of glucose and the mixture is heated to 1000C and maintained at this temperature for 10 hours. There are obtained 72 g of a green dye powder (12) in reduced form, which contains 5 % NaOH referred to the weight of the final dry product, is free of inorganic sulphides, is readily and completely soluble in water and dyes cotton in intense green shades, when applied in the presence of suitable reducing agents (e.g. glucose) and sodium hydroxide and with subsequent oxidation.

Example 13 a) A mixture of 140 g of sulphur and 45 g of 2,4-diaminotoluene is baked at 3001C in a rotary drum for 24 hours. The obtained solid product is dissolved in 200 g of water and 150 g of NaOH at the boil during 2-4 hours. The obtained mixture is diluted with 800 g of water and air is passed through the solution until the sulphide is oxidized and the dye is precipitated. The pE is then adjusted to 7 by addition of sulphuric acid, the obtained mixture is vacuum filtered and the presscake is washed with water.

b) The obtained filter cake (with a water content of 75-85 X) is admixed with 60 g of aqueous 50 % sodium hydroxide, 18 g of glucose and 15 g of sodium bisulphite. Then the mixture is reacted and dried simultaneously at 120-130'C in an evaporating pan during 10 hours. There are obtained 130 g of dry leuco sulphur orange (13) which is readily and completely soluble in water and that, suitably applied in the presence of a reducing agent as indicated above and of NaOH and then oxidized, gives dye- ings of deep yellowish orange shades on cotton.

Example 14

Case 150-5508 250 g of the filter cake obtained according to Example 1 part a) are mixed with 64 g of aqueous 50 % sodium hydroxide, 15 g of glucose and 16 g of sodium bisulphite. 28 g of this mixture are put in the form of a thin layer into an evaporating pan, heated to 150-1601C and dried within 10 minutes. There are obtained 7 g of dry black product (14) which is readily and completely soluble in water, is free of inorganic sulphides and is stable to air oxidation even in the form of a 1 % aqueous solution of the product.

The respective filter cakes of Examples 5 a) and 6 a) and the refluxed mixture of Example 2 a) can be reduced and dried in an analogous way as described in Example 14 for the filter cake of Example 8 a).

Composition 1 g of the dry product (1) obtained according to Example 1 are dissolved in 210 g of water, together with 66 g of urea, 10 g of diethylenglycol monoethylether and 10 g of aqueous 40 % sodium xylene sulphonate and heated to 70C during 20-30 minutes, cooled to 401C and treated with 10 g of monoethanolamine and 2.5 g of thiourea dioxide. There is obtained a good solution of the reduced dye, which is free of sulphides and polysulphides and has a high stability to oxidation and film-formation and further has a low affinity for cotton; by applying the leuco dye on cotton in the presence of a suitable reducing agent as indicated above (e. g. glucose) and of sodium hydroxide and with subsequent oxidation there may be obtained deep black cotton dyeings: of optimum fastnesses.

Compositions 7, 8 and 14 The procedure described for Composition 1 is repeated, with the difference that in place of 50 g of product (1) there are employed 50 g of product (7), (8) or (14). There are obtained good solutions of the respective reduced dyes, which are free of sulphides and polysulphides and have a high stability to oxidation and film-formation and further have a low affinity for cotton; by applying the leuco dyes on cotton in the presence of a sui- Case 150-5508 table reducing agent as indicated above (e.g. glucose) and of sodium hydroxide and with subsequent oxidation there may be obtained deep black cotton dyeings of optimum fastnesses.

Compositions 2, 3, 4, 5, 6, 9, 10, 11, 12 and 13 The procedure described for Composition 1 is repeated, with the difference that in place of product (1) there are employed the products (2), (3), (4), (5), (6), (9), (10), (11), (12) and (13) respectively, in amounts corresponding to the respective solubilities.

Application Example A g of the leuco sulphur dye powder (1) obtained according to Example 1 are dissolved in 60 ml of water, containing 0.1 g of EDTA (ethylene diamine tetraacetic acid sodium salt) and 0.1 g of a commercial wetting agent (alkylphosphate). 2.5 g of dextrose and 2.0 g of aqueous 50 % sodium hydroxide solution are then added thereto and the obtained mixture is diluted with cold water up to a total volume of 100 ml. A cotton fabric of 50 cm x 8 cm with a weight of 10 g is padded with this liquor to a pick-up of 100 % and then steamed for one minute at 102C. The steamed fabric is then rinsed with water and oxidized during one minute in a solution of 7 g/1 of 30 hydrogen peroxide and 7 g/1 of 80 % acetic acid at SOOC. Finally the treated fabric is dried. There is obtained a deep black dyeing with good fastnesses to washing, rubbing and light. After the dyeing procedure the machine used for the dyeing is much cleaner than after a dyeing obtained in the same way but with a sodium sulphide- containing dye obtained in conventional known manner.

Application Example Abis Application Example A is repeated with the difference that in place of the leuco sulphur dye powder (1) there is employed the leuco sulphur dye powder (7), (8) or (14). There are obtained deep black dyeings with good fastnesses to washing, rubbing and light. After the dyeing procedure the machine used for the dyeing is much cleaner than after a dyeing obtained in the same way but with a sodium sulphide-containing dye obtained in conventional known manner.

Application Example B Case 150-5508 I g of the dry leuco sulphur dye powder (1) obtained according to Example 1 is added into a solution of 200 ml of water, 0.2 g of EDTA, 0.2 g of wetting agent (as used in Application Example A), 0.8 g of dextrose and 0. 8 g of 50 % sodium hydroxide solution and stirred until the dye is dissolved. A cotton skein of 10 g is introduced into this liquor and the bath is heated during 15 minutes to 95C, while continuously moving the skein, and then maintained for 20 minutes at this temperature. 8 g of sodium chloride are then added and dyeing is continued for further 30 minutes at 950C, after which the treated skein is taken out from the bath, washed with water and treated during 15 minutes with a solution of 0.5 g1l of hydrogen peroxide and 0.5 g/1 of acetic acid at 50C for oxidation of the dye. Upon oxidation the skein is washed and dried. There is obtained a deep black dyeing of good fastnesses.

Application Example Bbis Application Example B is repeated with the difference that in place of the leuco sulphur dye powder (1) there is employed the leuco sulphur dye powder (7), (8) or (14). There are obtained deep black dyeings of good fastnesses.

Analogously as the leuco sulphur dye powders (1), (7), (8) and (14) according to Examples 1, 7, 8 and 14 the leuco sulphur dye powders (2), (3), (4), (5), (6), (1a), (2a), (3a), (4a), (1b), (2b), (3b), (4b), (1c), (2c), (3c), (4c) (9), (10), (11), (12), (13), (8a), (9a), (10), (11a), (8b), (9b), (10b), (11b), (8c), (9c), (10c) and (11c) may be employed in Application Examples A and B giving dyeings of corresponding shades. In place of the dry powders there may be employed the corresponding liquid formulations Compositions 1 to 14.

Application Example C 0.5 g of the black leuco sulphur dye powder (1) obtained according to Example 1 are given with stirring into 500 ml of a 1 % paper stuff suspension. After 10 minutes 0.1 g of rosin size (sodium rosinate) and a sufficient Case 150-5508 amount of aluminium sulphate to give a pH of 4.5 to 5.0 are added, by which the dye is precipitated on the paper stuff. A paper sheet is formed of the dyed paper stuff. The paper is dyed in a deep black, the drained liquor is completely transparent, colourless and free of inorganic sulphides.

Analogously as the leuco sulphur dye powder (1) according to Example 1, the leuco sulphur dye powders (2), (3), (4), (5), (6), (7), (1a), (2a), (3a), (4a), (1b), (2b), (3b), (4b), (1c), (2c), (3c) and (4c) may be employed in Application Example C giving paper dyeings of corresponding shades. In place of the dry powders there may be employed the corresponding liquid formulations Compositions 1 to 7.

- 24

Claims (24)

1. Case 150-5508 1. A process for the production of a hydrosoluble dry leuco sulphur dye (L) wherein a sulphur dye (S) is reacted in aqueous medium at a temperature above 60C with an efficient amount of (A) a reducing carbonyl compound in the presence of (B) an alkali metal hydroxide, and dried.
2. 2. A process according to Claim 1 for the production of a hydrosoluble leuco sulphur dye (L) wherein a sulphur dye (S) is reacted in aqueous medium at a temperature above 601C with an efficient amount of (A) in the presence of (B) and (C) an alkali metal sulphite and/or bisulphite, and dried.
3. 3. A process according to Claim 1 wherein the total water content of the aqueous mixture of (S), (A) and (B) at the beginning of the reaction is 95 % by weight.
4. 4. A process according to Claim 2 wherein the total water content of the aqueous mixture of (S), (A), (B) and (C) at the beginning of the reaction is < 95 % by weight.
5. 5. A process according to Claim 3 wherein the aqueous mixture of (S), (A) and (B) at the beginning of the reaction has a water content of 20 to 80 % by weight.
6. 6. A process according to Claim 4 wherein the aqueous mixture of (S), (A), (B) and (C) at the beginning of the reaction has a water content of 20 to 80 % by weight.

   Case 150-5508
7. 7. A process according to any of Claims 1 to 6 characterized by drying without exclusion of air.
8. 8. A process according to any of Claims 1 to 7 characterized by reacting without exclusion of air.
9. 9. A process according to any of Claims 1 to 8, wherein (S) is employed in the form of an aqueous (S)-containing mass (P).
10. 10. A process according to Claim 9, wherein (P) is an aqueous reaction mass of the production of the sulphur dye (S), with a water content of 8 to 95 X.
11. 11. A process according to Claim 9 or 10 wherein (P) is a wet filter cake with a water content of 8 to 95 %.
12. 12. A process according to any of Claims 1 to 11 wherein (A) is an aldo or keto sugar.
13. 13. A process according to any of Claims 1 to 12 wherein the drying is carried out at least in part simultaneously with the reduction reaction.
14. 14. A dry leuco sulphur dye (L) as obtainable by a process according to any of Claims 1 to 13.
15. 15. A dry leuco sulphur dye (L) according to Claim 14 and containing an excess of alkali metal hydroxide (B).
16. 16. A process for the dyeing of substrates dyeable with sulphur dyes wherein the substrates are dyed with leuco sulphur dyes (L) according to Claim 14 or 15.
17. 17. A process according to Claim 16 wherein cellulosic textile material is dyed in alkaline medium in the presence of a sulphide-free reducing agent and with subsequent oxidation.
18. 18. A process according to Claim 16, wherein a paper pulp suspension is Case 150-5508 dyed with (L) with subsequent treatment with a size and/or a floccula- ting, de-watering and/or retention agent.
19. 19. A concentrated aqueous (Q-containing composition wherein (L) is as defined in Claim 14 or 15.
20. 20. An aqueous composition according to Claim 19 further containing a solubilizing agent and/or an anionic surfactant and/or a sulphide-free reduction stabilizer.
21. 21. A process according to any of Claims 1 to 13 substantially as hereinbefore described and as specifically disclosed in any of Examples 1 to 14.
22. 22. A dry leuco sulphur dye (L) according to Claim 14 or 15, substantially as hereinbefore described and as specifically disclosed in any of Examples 1 to 14.
23. 23. A composition according to Claim 19 or 20 substantially as hereinbefore described and as specifically disclosed in any of exemplified Compositions 1 to 14.
24. 24. A process according to any of Claims 16 to 18 substantially as hereinbefore described and as specifically disclosed in any of Application Examples A to C or in the appendices thereto after Application Example Bbis or after Application Example C.