DYEING PROCESS AND DYE COMPOSITION

Abstract: A process for dyeing fibrous substrates which comprises the steps of providing a fibrous substrate; providing at least one optionally (pre)reduced sulphur dye; providing at least one reduction stable direct dye; and optionally providing at least one vat dye; and applying said reduction stable direct dye and said optionally (pre)reduced sulphur dye and optionally said vat dye to said fibrous substrate in the presence of a suitable reducing agent and then reoxidising.

Description: DYEING PROCESS AND DYE COMPOSITION The present invention is directed to a process for dyeing fibrous substrates which comprises the steps of: providing a fibrous substrate; providing at least one sulphur dye; providing at least one reduction stable direct dye; and applying said reduction stable direct dye to said fibrous substrate in the presence of a suitable reducing agent. As has been known for many years, sulphur dyes are advantageously used in the dyeing and/or printing of cellulose fiber materials and/or cellulosic blended textile fibers. In traditional dyeing processes the sulphur dyes are applied in the alkali soluble (pre)reduced form, i.e. "leuco state", and are brought in contact with the cellulosic fibers in one of a variety of methods and subsequently oxidised in order to achieve colour development and/or impart a degree of dye fastness to the dyed cellulosic textile substrate. Reducing agents traditionally employed for the application of sulphur dyes are in particular: sodium hydrogen sulphide, sodium sulphide and sodium polysulphides. Other chemical reducing agents that do not contain sulphide ions (i.e. "non-sulphide" reducing agents) known to be useful for the reduction of sulphur dyestuffs include: sodium borohydride, formamidinesulphinic acid, glyceraldehyde, hydroxyacetone, sodium formaldehydesulphoxylate, sodium hydrosulphite, thioglycolic acid, and various reducing sugars, and mixtures thereof with hydroxylamine sulphate, lignin sulphonates. The prior art teaches the processing of only sulphur dyes in a reducing medium. It has been believed that the use of direct dyes in such conditions would result in the destruction of the chromophore. Direct dyes may have been used to shade sulphur dyeings but not applied in combination with sulphur dyes dyed simultaneously in a reduction medium. US patent 3415808 describes the dyeing of cellulosic substrates with certain vattable azo dyes of lower vatting rate, there being mentioned in particular azo dyes containing a benzazolylphenylazo group (in which the azolyl ring contains a further heteroatom and may be oxazolyl, thiazolyl, imidazolyl or triazolyl) under alkaline conditions, in the presence of an excess of a strong reducing agent, there being mentioned reducing agents containing a sulphine or sulphite group; further this patent mentions also the addition of a vat dye or other vattable quinoid compound to catalyse the vatting of the azo dye. CONFIRMATION COP* It has now surprisingly been found that by dyeing fibrous substrates with a sulphur dye in leuco form and a reduction stable direct dye under reductive conditions and then reoxidising, there may be obtained dyeings of notable quality (especially colouristic and fastness quality) while there may be employed a low proportion of reducing agent - even of a substantially sulphur-free mild reducing agent such as a reducing sugar. The invention thus provides a process for dyeing fibrous substrates which comprises the steps of: providing a fibrous substrate; providing at least one optionally (pre)reduced sulphur dye; providing at least one reduction stable direct dye; applying said reduction stable direct dye and sulphur dye optionally in (pre)reduced form to said fibrous substrate in the presence of a suitable reducing agent and then reoxidising. Further, it has been surprising to find that reduction stable direct dyes can be processed with optionally (pre)reduced sulphur dyes and also vat dyes. The result is a process for dyeing fibrous substrates which comprises the steps of: providing a fibrous substrate; providing at least one optionally (pre)reduced sulphur dye and at least one vat dye; providing at least one reduction stable direct dye and a suitable reducing agent; and applying said reduction stable direct dye, and vat dye and the sulphur dye optionally in (pre)reduced form to said fibrous substrate in the presence of a suitable reducing agent and then reoxidising. As sulphur dyes come, in general, into consideration conventional dyes known under this concept and as defined as "Sulphur Dyes" and "Sulphurized Vat Dyes" in VENKATARAMAN "The Chemistry of Synthetic Dyes" Vol. II (Chapters XXXV and XXXVI) (1952) and Vol. VII ( 1974) or as defined e.g. in the "Colour Index" as "Sulphur Dyes" and also as "Vat Dyes" with the further indication "sulphur" and/or with a structure number and a synthetic method involving a sulphurization, e.g. as indicated in VENKATARAMAN as sulphurized vat dyes. 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 100°C, in particular in the temperature range of 1 10-300°C (e.g. by baking or in the melt or in the presence of water and/or of an inert organic solvent). As vat dyes come, in general, into consideration conventional dyes known under this concept and as defined as "Vat Dyes" e.g. in the "Colour Index" and that do not contain any oligosulphide bridges. Essentially they are dyes that contain a conjugated pair of carbonyl groups that on vatting are reversibly reduced to corresponding hydroxymethylene groups, such as e.g. a quinonic grouping that is reversibly reduced to the corresponding hydroquinonic grouping. Among the sulphurised vat dyes are in particular meant those with typical sulphur dye character, i.e. containing oligosulphide bridges and preferably not containing conjugated pairs of carbonyl groups. A preferred kind of sulphurized vat dyes is represented by those of the carbazole-group-containing indophenol series. The fibrous substrate is selected from the group of: cellulosic fibrous material, cellulosic-mixed fiber materials and blends of cellulosic fibers with synthetic non-cellulosic fiber. By "cellulosic fibrous material" it is to be understood a substrate which comprises cellulose fibers and which may further comprise non-cellulosic fibers, which may be mixed with the cellulosic fibers, and is preferably textile material. Contemplated non-cellulosic fibers include semi-synthetic and fully synthetic polymeric fibrous material including, but not limited to, cellulose acetates, polyamides (alkyl and aromatic), polyesters, polyolefin, polyacrylonitrile, as well as others known in the art as useful in forming mixed fiber blends with cellulose fibers. Further, the fibers may be in any conventional form, including, but not limited to, raw stock, threads, yarns, or in semi-finished product form, that is to mean, in the form of twisted hanks or skeins of yarns or fibers, spooled threads, knitted or woven textile such as fabrics, as well as in final product form such as garments. The sulphur dyes (S) which may be used in accordance with the process of the invention include those which are either provided in the non-reduced form (Si) for subsequent reduction by suitable sulphur dye reducing agent(s) in the application bath, or they may be provided to the bath as pre-reduced sulphur dyes (S 2 ), in particular as liquid concentrated compositions, which are frequently aqueous alkaline solutions containing the alkali soluble leuco sulphur dye thiolate, or as dry compositions. As pre-reduced sulphur dyes (S 2 ) there are more specifically meant pre-reduced sulphur dyes which are in a partially reduced form as is sufficient in order to be readily soluble in alkaline solutions and which may, if desired, be further reduced for application, and further or fully reduced sulphur dyes which are readily soluble in alkaline solutions and are directly usable for application. Both are embraced by the term leuco sulphur dyes. Solubilised sulphur dyes (Bunte salts) (S 3 ) may also be employed according to the invention. Exemplary sulphur dyes (S) which may be utilised in accordance with the process of the invention include but are not necessarily limited to the following ("C.I." stands for "Colour Index"): C.I. Sulphur Yellow 1, 2, 3, 4, 5, 6, 8, 9, 10, 11, 12, 13, 14, 16, 20 and 23, C.I. Leuco Sulphur Yellow 2,4,7,9, 12, 15, 17, 18, 21, 22 and 23 and C.I. solubilised Sulphur Yellow 2, 4, 5, 19, 20 and 23; C.I. Sulphur Orange 1, 2, 3, 4, 5, 6, 7 and 8, C.I. Leuco Sulphur Orange 1, 3, 5 and 9 and C.I. solubilised Sulphur Orange 1, 3, 5, 6, 7 and 8; C.I. Sulphur Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12 and 13, C.I. Leuco Sulphur Red 1, 4, 5, 6, 11 and 14 and C.I. Solubilised Sulphur Red 3, 6, 7, 11 and 13; C.I. Sulphur Violet 1, 2, 3, 4 and 5, C.I. Leuco Sulphur Violet 1 and 3 and C.I. Solubilised Sulphur Violet 1; C.I. Sulphur Blue 1,2,3,4,5,6, 7, 8,9, 10, 11, 12, 13, 14, 15, 16, 17, 18 and 19, C.I. Leuco Sulphur Blue 1, 2, 3, 5, 7, 8, 9, 11, 13, 15 and 20, C.I. Solubilised Sulphur Blue 1, 2, 4, 5, 6, 7, 10, 11, 13, and 15 and C.I. Vat Blue 43 (sulphur); C.I. Sulphur Green 1,2,3,4,5,6,7,8:1,9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19,20,21,22,23,24,25, 26, 27, 28, 29, 31, 32 and 33, C.I. Leuco Sulphur Green 1, 2, 3, 4, 7, 11, 1630, 34, 35, 36, and 37 and C.I. Solubilised Sulphur Green 1, 2, 3, 6, 7, 9, 19, 26 and 27; C.I. Sulphur Brown 1,2,3,4,5,6,7, 8,9, 10, 11, 12, 13, 14, 14:1, 15, 15:1, 16, 17, 18, 19,20,21,22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 53:1, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 76, 77, 78, 79, 84, 85, 87, 88, 89, 90, 91, 93 and 94, C.I. Leuco Sulphur Brown 1, 3, 4, 5, 8, 10, 11, 12, 14, 15,21,23,26,31,37,43,44, 81, 82,86,87,90,91,92,93,94,95 and 96 and C.I. Solubilised Sulphur Brown 1,4,5,8, 10, 11, 12, 14, 15, 16, 21, 26, 28, 31, 51, 52, 56, 60, 75, 80 and 83; C.I. Sulphur Black 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 and 17, C.I. Leuco Sulphur Black 1, 2, 6, 9, 10, 11 and 18 C.I. Solubilised Sulphur Black 1 , 2, 5, 7 and 11. A more complete and particularised listing of the dyestuffs mentioned above may be found in the Colour Index, 3rd. Ed., published by the Society of Dyers and Colourists (London, GB), as well as in the supplementary volumes published thereto. The sulphur dyes (S) may be employed in a form as commercially available; the soluble reduced or pre- reduced, i.e. leuco sulphur dyes (S 2 ), may in particular be employed in a form as commercially available, and which may contain some residual excess reducing agent from their production, and, especially in the liquid form, may contain if required or desired, some added reducing agent in order to stabilise the reduced form against an oxidising influence of the surrounding air. The reduction stable direct dye has proven to be a surprising element in this process. Sulphur dyes are - as already mentioned above - defined as, one of a group of dyes produced by heating various organic compounds with sulphur. The characteristic groupings in the chromophore in the oxidised form are ≡C-(S) n -Cs where the two carbons are ring members of two distinct aromatic rings and n is a figure indicating the oligomeric degree of the oligosulphide bridge, mostly a figure in the range of 2 to 4; C.I. numbers range from 53000 to 54999. Like Vat dyes, sulphur dyes are reduced to a water-soluble, "leuco", form for application - in particular to the corresponding thiolate form - and are then reoxidised to their original coloured state for fixation. However it has been discovered that these direct dyes, which are not classified as sulphur dyes or vat dyes, can be processed like sulphur dyes and colour yield is unaffected or improved after reduction application and reoxidation. A prime example of this is C.I. Direct Blue 86, 189 or 199. These colours are all classified as direct dyes, and yet surprisingly the chromophore is not destroyed by the reduction process and colour strength improved over the current art of applying these colours as direct dyes. In addition, it was found that enhanced wash fastness properties were obtained. C.I. Direct Yellow 148: 1 and C.I. Direct Yellow 29 also behave in this manner. For purposes of this invention reduction stable does not mean inert or unaffected by the reduction. Reduction stable as used in this specification and claims means: a compound whose chromophore is not destroyed by undergoing reduction. While the original colour of the compound may be altered by the reduction it still yields a commercially acceptable colour, especially upon reoxidation. Surprisingly, many of these direct dyes exhibit enhanced tinctorial strength or improved wash fastness or both when processed in a reducing medium. When these reduction stable direct dyes are processed together with sulphur dyes or combinations of sulphur dyes and vat dyes, enhanced tinctorial strength or improved wash fastness or both improved wash fastness and tinctorial strength has been observed in some cases when processed in a reducing medium. In many cases these increases are more than an additive effect which suggests an unexpected synergy between these components. Suitable reducing agents include sodium hydrogen sulphide, sodium sulphide and sodium polysul- phides. Other chemical reducing agents that do not contain sulphide ions (i.e. "non-sulphide" reducing agents) known to be useful for the reduction of sulphur dyestuffs include: sodium borohydride, formamidinesulphinic acid, sodium formaldehydesulphoxylate, sodium hydrosulphite, thioglycolic acid, and sulphur free reducing agents, preferably glyceraldehyde, hydroxyacetone and various reducing sugars, e.g. glucose or dextrose, and mixtures of one or more thereof with hydroxylamine sulphate or lignin sulphonates. The non-sulphide reducing agent(s) (R) are preferred for environmental reasons. These non-sulphide reducing agent(s) (R) can be employed in the dyebath; it may be utilised to reduce a sulphur dye (Si) or (S 3 ) or a pre-reduced dye present in the dyebath or to maintain the reduced condition (leuco form) of pre-reduced dyes (S 2 ). The dyeing is suitably carried out under alkaline conditions, preferably at a pH ≥ 10, usually with Na 2 C0 3 or NaOH. The liquor-to-goods ratio may be in any range as suitable for the particular method of dyeing and machine used. The concentration of (R) may be chosen depending on amount and concentration of the dye and on the nature of (R) and may further vary depending on the kind of substrate and particular dyeing method. The reducing agent (R) is suitably added in any amount which is found to adequately reduce a sulphur dye, in particular (Si) and also (S 3 ) to its reduced form under the operating dyeing conditions, and/or to maintain the reduced condition of pre-reduced sulphur dyes, in particular (S 2 ). Also the dyeing temperature may vary depending on the dyeing method and apparatus, and is advantageously in the range 35° to 130° C. The dyeing can then be completed by reoxidation, which may be carried out by aeration or by addition of a conventional oxidising agent, preferably a peroxide, a persulphate or a catalysed bromate. The reduction stable direct dyes can also be prepared as pourable aqueous liquid suspensions capable of reduction. These pourable aqueous liquid suspensions capable of reduction, consisting essentially of: a reduction stable direct dye; and a suspension stabilising agent in an amount effective to maintain a uniform distribution of reduction stable direct dye in suspension for a period of at least 24 hours. The suspension stabilising agent being one or more water-soluble compounds being present in an amount of less than 10 % by weight of the suspension. This suspension stabilising agent is preferably selected from the group of carboxymethyl cellulose; xanthan gum; gum arabic; polyacrylamide; and combinations thereof. These pourable aqueous suspensions can optionally further contain of a preservative, especially a biocide or a fungicide or combinations thereof, to control or inhibit growth of unwanted microorganisms. This becomes important in cases where the suspension may be stored before use. Usually these additives are added in a range of 0.01 to 0.5 % by weight of the liquid phase of the suspension. An example of a biocide would be a glutaraldehyde biocide AMA-4750. An example of a fungicide is Givgard DXN. Preservative as used here can mean a biocide, fungicide or any other substance, known in the art, which prolongs the useful life of the suspension. Dye blends containing both sulphur and direct dyes can be prepared as a pourable aqueous liquid suspension capable of reduction. This pourable aqueous liquid suspension capable of reduction consists essentially of: a sulphur dye; a reduction stable direct dye; and a suspension stabilising agent in an amount effective to maintain a uniform distribution of sulphur dye in suspension for a period of at least 24 hours. This suspension stabilising agent being present preferably in an amount of less than 10 % by weight of the suspension. The preferred sulphur dye present has a content of inorganic sulphides and inorganic polysulphides, such that, upon being acidified to pH 3 in phosphoric acid at 22° C will generate no more hydrogen sulphide than can react with aqueous sodium hydroxide to form 1000 ppm of sulphide ion based on the weight of the sulphur dye. The suspension stabilising agent is preferably selected from the group of: carboxymethyl cellulose; xanthan gum; gum arabic; polyacryl- amide; and combinations thereof. The said sulphur dye is selected from the group of: non-reduced sulphur dyes (Si); pre-reduced sulphur dyes (S 2 ); and solubilised sulphur dyes (Bunte salts) (S 3 ). The sulphur dye/direct dye blend can be stabilised or further concentrated through the addition of a suspension stabilising agent. In the sulphur dye /direct dye blend, additives can be added to prolong the life of the blend. The additive is preferably selected from the group of preservatives, such as biocides, fungicides and combinations thereof. A further dye blend containing at least one direct dye, at least one vat dye and at least one optionally (pre)reduced sulphur dye can be prepared as a pourable aqueous liquid capable of reduction, comprising: at least one vat dye, at least one optionally (pre)reduced sulphur dye and at least one reduction stable direct dye. While many vat dyes can be used, C.I. Vat Blue 1, C.I. Vat Blue 2, C.I. Vat Blue 3, C.I. Vat Blue 4 are all of interest. C.I. Vat Blue 1, or Indigo, has demonstrated a particular synergistic effect when combined with certain reduction stable direct dyes and with sulphur dyes. The sulphur dye is selected from the group of: non-reduced sulphur dyes (Si); solubilised sulphur dyes (Bunte salts) (S 3 ); and combinations thereof, (pre)reduced sulphur dyes (S ) may alternatively be used. The resulting vat/sulphur/direct dye blend can be further modified with suspension agents, and additive to protect against micro-organisms. Multiples of vat or sulphur or direct dyes or combinations thereof can be prepared to achieve colours that have not been achievable with only sulphur or vat dyes at present. In using sulphur dyes in many cases a dispersing agent will be added. The dispersing agent is preferably anionic and is more preferably selected from the group of: lignin sulphonates; naphthalene- sulphonic acid formaldehyde condensates. The suspension agents and preservatives, i.e. additives to protect against micro-organisms already discussed, can be used in conjunction with the dispersing agents. Any combination of dispersing agents, suspension agents and additives can be used with either the sulphur dye/direct dye blend or vat dye/sulphur dye/direct dye blend. The invention thus provides also a process for dyeing fibrous substrates, which comprises the steps of: providing a fibrous substrate; providing at least one optionally (pre)reduced sulphur dye; providing at least one vat dye; providing at least one reduction stable direct dye; and applying said reduction stable direct dye, vat dye and optionally (pre)reduced sulphur dye to said fibrous substrate in the presence of a suitable reducing agent and then reoxidising. The fibrous substrate is selected from the group of: cellulosic fibrous material, cellulosic-mixed fiber materials and blends of cellulosic fibers with synthetic non-cellulosic fiber. Suitable reducing agents are selected from the group of: sodium hydrogen sulphide; sodium sulphide; sodium polysulphides; sodium borohydride; formamidinesulphinic acid; glyceraldehyde; hydroxyacetone; sodium formaldehydesulphoxylate; sodium hydrosulphite; thio- glycolic acid; and various reducing sugars, and combinations of one or more thereof with hydroxyl- amine sulphate or lignin sulphonates. The process for dyeing with a blend of vat dyes, optionally (pre)reduced sulphur dyes and reduction stable direct dyes comprises the steps of: providing said dyes, applying said dyes to said fibrous substrate in the presence of a suitable reducing agent and then reoxidising. The sulphur dye is selected from the group of: non-reduced sulphur dyes (Si); solubilised sulphur dyes (Bunte salts) (S 3 ); and combinations thereof and (pre)reduced sulphur dyes (S 2 ). The fibrous substrate is selected from the group of: cellulosic fibrous material, cellulosic-mixed fiber materials and blends of cellulosic fibers with synthetic non-cellulosic fiber. Suitable reducing agents are selected from the group of: sodium hydrogen sulphide; sodium sulphide; sodium polysulphides; sodium borohydride; formamidinesulphinic acid; glyceraldehyde; hydroxyacetone; sodium formaldehydesulphoxylate; sodium hydro- sulphite; thioglycolic acid; and various reducing sugars, and combinations of one or more thereof with hydroxylamine sulphate or lignin sulphonates;. In the following Examples the percentages are by weight and the temperatures are indicated in degrees Celsius. Example 1 A dyeing of a textile substrate in a laboratory dyeing apparatus was performed as follows: 10 g of 100% cotton knit interlock is placed in a 150 ml stainless steel dye canister containing 100 ml of dyebath. The dyebath is an aqueous solution consisting of 1 g/L Sandopure SD, 20 g/L sodium sulphate, 6 g/L soda ash, 4 g/L caustic soda 50% liquid, 9 g L Sandozol ® Reducer RDT-L liquid, 1.1 g of C.I. Sulphur Blue 15, and 0.4 g C.I. Direct Blue 199. The dye canister is then placed in a Zeltex Polycolor laboratory dyeing machine preheated to 50°C. The dyeing machine is then heated to 93°C at 3°C/minute. The dyeing machine is held at this temperature for 30 minutes and then cooled to 60°C at 3° C/minute. The dyeing canister is then removed from the dyeing machine and the fabric rinsed under running tap water until clear. The dyed fabric is then oxidised in 100 ml solution containing 1 g/L soda ash and 2 g/L Clariant ® Oxidiser A powder at 60°C for 15 minutes. The fabric is then rinsed with cold water and dried. A bright greenish blue shade having good wash fastness was obtained. Example 2 A dyeing of a textile substrate in a laboratory continuous dyeing apparatus was performed as follows a 100% cotton twill is padded at 68-74% wet pick-up with a dyebath solution. The dyebath is an aqueous solution consisting of 75 g/L caustic soda 50% liquid, 75 g L Sandozol ® Reducer RDT-L liquid, 15 g/L sodium hydrosulphite, 122.5 g/L C.I. Sulphur Black 1 and 75 g/L C.I. Direct Blue 199. The dyebath is then heated to 50°C and held for 5 minutes at this temperature. Then the dyebath solution is added to the dye pad trough. The fabric is then padded through the dyebath solution and steamed for 1 minute at 100-103°C. The dyed fabric is then washed under running tap water until clear. The dyed fabric is then oxidised in an aqueous solution containing 7.5 g/L acetic acid (glacial) and 7.5 g/L Clariant ® Oxidiser B liquid at 60°C for 30 seconds. The fabric is then rinsed with cold water and dried. A bright bluish black shade unachievable with sulphur dyes having good wash fastness was obtained. Example 3 A dyeing of a textile substrate in a laboratory continuous dyeing apparatus was performed as follows a 100% cotton unmercerized denim fabric is padded at 68-74% wet pick-up with a dyebath solution. The dyebath is an aqueous solution consisting of 7.5 g/L Penetrant ® EH, 22.5 g/L Sulfalox ® 100, 45 g/L caustic soda 50% liquid, 75 g/L Sandozol ® Reducer RDT-L liquid, 150 g/L C.I. Leuco Sulphur Black 1, and 75 g/L C.I. Direct Blue 199. The dyebath is then heated to 70°C. Then the dyebath solution is added to the dye pad trough. The fabric is then padded through the dyebath solution and steamed for 1 minute at 100-103°C. The dyed fabric is then washed under running tap water until clear. The dyed fabric is then oxidised in an aqueous solution containing 7.5 g/L acetic acid (glacial) and 7.5 g/L Clariant ® Oxidiser B liquid at 60°C for 30 seconds. The fabric is then rinsed with cold water and dried. A unique bright, bluish black shade unachievable with sulphur dyes having good wash fastness was obtained. Example 4 (Comparative Example) A dyeing of a textile substrate in a laboratory continuous dyeing apparatus was performed as follows a 100% cotton twill is padded at 68-74% wet pick-up with a dyebath solution. The dyebath is an aqueous solution consisting of 7.5 g/L Penetrant ® EH, 10 g/L sodium chloride, and 75 g L C.I. Direct Blue 199. The dyebath is then heated to 38°C. Then the dyebath solution is added to the dye pad trough. The fabric is then padded through the dyebath solution and steamed for 1 minute at 100-103°C. The dyed fabric is then washed under running tap water until clear. The dyed fabric is then oxidised in an aqueous solution containing 7.5 g/L acetic acid (glacial) and 7.5 g/L Clariant ® Oxidiser B liquid at 60°C for 30 seconds. The fabric is then rinsed with cold water and dried. A bright turquoise blue shade was obtained. This fabric exhibited poor wash fastness. Example 5 A dyeing of a textile substrate in a laboratory dyeing apparatus was performed as follows 10 g of 100 % cotton knit interlock is placed in a 150 ml stainless steel dye canister containing 100 ml of dyebath. The dyebath is an aqueous solution consisting of 1 g/L Sandopure ® SD, 20 g/L sodium sulphate, 6 g/L soda ash, 4 g/L caustic soda 50% liquid, 9 g/L Sandozol ® Reducer RDT-L liquid, 1.05 g C.I. Sulphur Blue 15, 0.096 g C.I. Direct Yellow 29, and 0.026 g C.I. Direct Blue 199. The dye canister is then placed in a Zeltex Polycolor laboratory dyeing machine preheated to 50°C. The dyeing machine is then heated to 93°C at 3°C/minute. The dyeing machine is held at this temperature for 30 minutes and then cooled to 60°C at 3°C/minute. The dyeing canister is then removed from the dyeing machine and the fabric rinsed under running tap water until clear. The dyed fabric is then oxidised in 100 ml solution containing 1 g/L soda ash and 2 g/L Clariant ® Oxidiser A powder at 60°C for 15 minutes. The fabric is then rinsed with cold water and dried. A bright blue-green shade having good overall wet fastness properties was obtained. Example 6 A dyeing of a textile substrate in a laboratory dyeing apparatus was performed as follows: 10 g of 100 % cotton knit interlock is placed in a 150 ml stainless steel dye canister containing 100 ml of dyebath. The dyebath is an aqueous solution consisting of 20 g/L sodium sulphate, 6 g/L soda ash, 4 g/L caustic soda 50% liquid, 9 g/L of an aqueous 53 % glucose solution, 1.1 g of C.I. Sulphur Blue 15, and 0.4 g C.I. Direct Blue 199. The dye canister is then placed in a Zeltex Polycolor laboratory dyeing machine preheated to 50°C. The dyeing machine is then heated to 93°C at 3°C/minute. The dyeing machine is held at this temperature for 30 minutes and then cooled to 60°C at 3° C/minute. The dyeing canister is then removed from the dyeing machine and the fabric rinsed under running tap water until clear. The dyed fabric is then oxidised in 100 ml solution containing 1 g/L soda ash and 1 g/L sodium persulphate at 60°C for 15 minutes. The fabric is then rinsed with cold water and dried. A bright greenish blue shade having good wash fastness was obtained. Example 7 A dyeing of a textile substrate in a laboratory continuous dyeing apparatus was performed as follows a 100% cotton twill is padded at 68-74% wet pick-up with a dyebath solution. The dyebath is an aqueous solution consisting of 75 g/L caustic soda 50% liquid, 75 g/L of an aqueous 53 % glucose solution, 15 g/L sodium hydrosulphite, 122.5 g/L C.I. Sulphur Black 1 and 75 g/L C.I. Direct Blue 199. The dyebath is then heated to 50°C and held for 5 minutes at this temperature. Then the dyebath solution is added to the dye pad trough. The fabric is then padded through the dyebath solution and steamed for 1 minute at 100-103°C. The dyed fabric is then washed under running tap water until clear. The dyed fabric is then oxidised in an aqueous solution containing 7.5 g L acetic acid (glacial) and 7.5 g/L of a catalysed aqueous 13 % sodium bromate solution at 60°C for 30 seconds. The fabric is then rinsed with cold water and dried. A bright bluish black shade unachievable with sulphur dyes having good wash fastness was obtained. Example 8 A dyeing of a textile substrate in a laboratory continuous dyeing apparatus was performed as follows: a 100 % cotton unmercerized denim fabric is padded at 68-74% wet pick-up with a dyebath solution. The dyebath is an aqueous solution consisting of 22.5 g/L thioureadioxide, 45 g/L caustic soda 50% liquid, 75 g/L of an aqueous 53 % glucose solution, 150 g/L C.I. Leuco Sulphur Black 1 , and 75 g/L C.I. Direct Blue 199. The dyebath is then heated to 70°C. Then the dyebath solution is added to the dye pad trough. The fabric is then padded through the dyebath solution and steamed for 1 minute at 100-103°C. The dyed fabric is then washed under running tap water until clear. The dyed fabric is then oxidised in an aqueous solution containing 7.5 g/L acetic acid (glacial) and 7.5 g/L of a catalysed aqueous 13 % sodium bromate solution at 60°C for 30 seconds. The fabric is then rinsed with cold water and dried. A unique bright, bluish black shade unachievable with sulphur dyes having good wash fastness was obtained. Example 9 A dyeing of a textile substrate in a laboratory dyeing apparatus was performed as follows 10 g of 100% cotton knit interlock is placed in a 150 ml stainless steel dye canister containing 100 ml of dyebath. The dyebath is an aqueous solution consisting of 20 g/L sodium sulphate, 6 g/L soda ash, 4 g/L caustic soda 50% liquid, 9 g/L of an aqueous 53 % glucose solution, 1.05 g C.I. Sulphur Blue 15, 0.096 g C.I. Direct Yellow 29 and 0.026 g C.I. Direct Blue 199. The dye canister is then placed in a Zeltex Polycolor laboratory dyeing machine preheated to 50°C. The dyeing machine is then heated to 93°C at 3°C/minute. The dyeing machine is held at this temperature for 30 minutes and then cooled to 60°C at 3°C/minute. The dyeing canister is then removed from the dyeing machine and the fabric rinsed under running tap water until clear. The dyed fabric is then oxidised in 100 ml solution containing 1 g/L soda ash and 1 g/L sodium persulphate at 60°C for 15 minutes. The fabric is then rinsed with cold water and dried. A bright blue-green shade having good overall wet fastness properties was obtained.

Claims: CLAIMS 1. A process for dyeing fibrous substrates which comprises the steps of: providing a fibrous substrate; providing at least one optionally (pre)reduced sulphur dye; providing at least one reduction stable direct dye; and applying said reduction stable direct dye and sulphur dye optionally in (pre)reduced form to said fibrous substrate in the presence of a suitable reducing agent and then reoxidising. 2. A process according to Claim 1 for dyeing fibrous substrates which comprises the steps of: providing a fibrous substrate; providing at least one optionally (pre)reduced sulphur dye; providing at least one vat dye; providing at least one reduction stable direct dye; and applying said reduction stable direct dye, vat dye and sulphur dye optionally in (pre)reduced form to said fibrous substrate in the presence of a suitable reducing agent and then reoxidising. 3. A process for dyeing fibrous substrates according to Claim 1 or 2, wherein said reduction stable direct dye is selected from the group of: C.I. Direct Blue 86; C.I. Direct Blue 189; C.I. Direct Blue 199; C.I. Direct Yellow 148: 1 ; C.I. Direct Yellow 29; and combinations thereof. 4. A pourable aqueous liquid capable of reduction, comprising: a non-reduced or (pre)reduced sulphur dye; and a reduction stable direct dye and optionally a vat dye. 5. A pourable aqueous liquid capable of reduction, according to Claim 4, further comprising: a suspension stabilising agent in an amount effective to maintain a uniform distribution of sulphur dye in suspension for a period of at least 24 hours, said suspension stabilising agent being present in an amount of less than 10% by weight of the suspension. 6. A pourable aqueous liquid capable of reduction, according to Claim 4, wherein said sulphur dye has a content of inorganic sulphides and inorganic polysulphides such that upon being acidified to a pH 3 in phosphoric acid at 22° C will generate no more hydrogen sulphide than can react with aqueous sodium hydroxide to form 1000 ppm of sulphide ion based on the weight of the sulphur dye. 7. A pourable aqueous liquid according to Claim 4, further comprising a preservative.

Inventors: CARLOUGH MARK STUART, HIPP MICHAEL J, SHERRILL WILLIAM T, STAHALA PETER, CARLOUGH, MARK, STUART, HIPP, MICHAEL, J., SHERRILL, WILLIAM, T., STAHALA, PETER
Applicants: CLARIANT FINANCE BVI LTD, CLARIANT INT LTD, CLARIANT FINANCE (BVI) LIMITED, CLARIANT INTERNATIONAL LTD.
Application year: 1999
Main classification: D06P1
IPC codes: D06P1, D06P3