Colorant composition comprising leucoindigo for coloring fibers and fabrics

Abstract

The invention relates to a colorant composition for coloring fibers and fabrics comprising leucoindigo and at least one organic solvent. To achieve a stable composition, which is broadly applicable to different fibers and fabrics, the water content of the composition is less or equal to 10 wt.-% of the total weight of the composition or the water content of the composition is less or equal to 60 wt.-% of the total weight of the composition and the composition also includes a base.

Claims

1. A composition for coloring fibers and fabrics comprising leucoindigo, at least one organic solvent, wherein the water content of the composition is less or equal to 60 wt.-%, of the total weight of the composition, characterized in the composition further comprises at least one strong base, wherein the at least one strong base is an alkali metal hydroxide, an alkaline earth metal hydroxide or a mixture thereof, that the at least one organic solvent is selected from a first group of solvents consisting of ethylene glycol, propylene glycol, isopentyldiol, dipropylene glycol and mixtures thereof and that the composition comprises at least one reducing agent.

2. The composition of claim 1, wherein the at least one base is in the range of between 0.01 and 20 wt.-% of the total weight of the composition.

3. The composition of claim 1, wherein the composition comprises a second group of solvents, which is selected from solvents that are fully miscible with the first group of solvents and at least partially miscible with water.

4. The composition of claim 3, wherein the second group solvent is selected from ethanol, propanol, 1,3-propanediol, glycerin, butylene glycol, hexylene glycol, dimethyl isosorbide, acetamide MEA, ethoxydiglycol or mixtures thereof and/or that the total mass ratio of first to second group solvents is in the range of between 1:10 and 10:1.

5. Composition of claim 1, wherein the water content of the composition is below 1 wt.-%, of the total weight of the composition and/or that the leucoindigo is in the range of between 0.1 and 30 wt.-% of the total weight of the composition.

6. Composition of claim 1, wherein the at least one reducing agent is in the range of between 0.1 and 20 wt.-% of the total weight of the composition.

7. Composition of claim 1, wherein the reducing agent is ascorbic acid, erythorbic acid, hydroxyacetone, sodium dithionite, sodium sulfite, sodium metabisulfite, sodium borohydride, sodium thiosulfate, a reducing sugar or a mixture thereof.

8. A method for obtaining a composition as according to claim 1, characterized by the steps of: a) addition of at least one base and at least one reducing agent to a suspension of indigo in at least one organic solvent and b) heating the suspension of indigo until the vatting is complete.

9. The method of claim 8, wherein the at least one base is added as an aqueous solution in step a) and/or that water is added to suspension of step a) and/or that the mixture is heated in step b) to temperatures in the range of between 50 and 110 C.

10. A colorant mixture for coloring fibers and fabrics comprising a composition of 1 as first constituent and at least one further composition as a second constituent, characterized in that the second constituent is an aqueous composition.

11. The mixture of claim 10, wherein the second constituent comprises at least one organic acid, inorganic acid and/or buffer and/or that the water content of the second constituent is at least 50 wt.-% of the second constituent and/or that the mass ratio of first constituent to the second constituent in the range of between 1:2 to 1:8.

12. The mixture of claim 11, wherein the concentration of the least one organic acid, inorganic acid and/or buffer ranges is in the range of between 0.1 to 25 wt.-% of the total weight of the second constituent.

13. The mixture according to claim 12, wherein the least one organic acid is selected from citric acid, formic acid, acetic acid, tartaric acid, adipic acid, succinic acid, malic acid, maleic acid, fumaric acid, an alpha-hydroxy acid or mixtures thereof, the at least one inorganic acid is selected from phosphoric acid, phosphorous acid, hydrochloric acid, sulfuric acid, sulfurous acid or mixtures thereof and/or the at least one buffer is selected from acetate buffer, phosphate buffer, phosphate-citrate buffer, citrate buffer, tris(hydroxymethyl)aminomethane (TRIS) buffer, glycine buffer, tris(hydroxymethyl)aminomethane-glycine (TRIS-glycine) buffer and/or bicarbonate buffer and/or that the mixture's pH value is in the range of between 2.0 and 12.5.

14. The mixture of claim 10, wherein the mixture comprises a third constituent, wherein the third constituent comprises at least one further colorant compound.

15. The mixture of claim 14, wherein the at least one further colorant compound is selected from lawsone, campeche wood extract, redwood extract, myrobalan plum extract, quercetin and/or 3,4,5-trihydroxybenzoic acid and/or that the organic solvent or solvent mixture and/or the water content of the third constituent is/are the same as that of the first constituent and/or that the mass ratio of first constituent to third constituent is in the range of between 20:1 and 1:20 and/or that the mass ratio of the total amount of the first and third constituent to the second constituent is in the range of between 1:2 and 1:8.

16. A method for coloring fibers and fabrics comprising an application of the composition of claim 1 to for coloring fibers and fabrics, wherein the fibers are natural or artificial fibers selected from a group consisting of protein-, cellulose- or petrochemical-based fibers, and the fabrics are selected from the group consisting of keratin fibers, kapok, hemp, bamboo, flax, cotton, sisal, jute, kenaf, ramie, lyocell, soy or coconut, nylon, polyester, acrylic, spandex, olefin, synthetic fur, leather, neoprene, microfiber, acetate, silk, wool, or feathers.

17. A kit consisting of at least two constituents, wherein a first constituent comprises leucoindigo of claim 1 and a second constituent has a pH lower than the first constituent.

18. A method for coloring fibers and fabrics comprising an application of the composition of claim 10 to fibers and fabrics, wherein the fibers are natural or artificial fibers selected from a group consisting of protein-, cellulose- or petrochemical-based fibers, and the fabrics are selected from a group consisting of keratin fibers, kapok, hemp, bamboo, flax, cotton, sisal, jute, kenaf, ramie, lyocell, soy or coconut, nylon, polyester, acrylic, spandex, olefin, synthetic fur, neoprene, microfiber, acetate, silk, wool, leather, or feathers.

19. The composition of claim 1, wherein the water content of the composition is less or equal to 50 wt.-% of the total weight of the composition.

Description

EXAMPLES

(1) All color measurements on the substrates were performed with the Konica-Minolta Chromameter CM 3700 D in accordance with the European standard EN ISO 11664-4 ColorimetryPart 4: CIE 1976 L*a*b* Color space.

(2) The L*a*b* color space or CIELAB describes all perceptible colors. It uses a three-dimensional color space, in which the lightness value L* defines black at 0 and white at 100 with its axis is perpendicular to the color plane (a*, b*). The a*axis represents the green-red opponent colors, with negative values toward green and positive values toward red. The b* axis represents the blue-yellow opponents, with negative numbers toward blue and positive toward yellow.

(3) Color changes in the color of a substrate are usually expressed in E values, that are calculated according to the well-known formula

(4) $E={\left[{\left(L_1-L_0\right)}^2+{\left(a_1-a_0\right)}^2+{\left(b_1-b_0\right)}^2\right]}^{1/2}$
wherein the indices 0 and 1 stand for the values before and after the treatment, respectively.

(5) The designation jeans blue is based on the measurement results of five cotton tissues died with indigo. The obtained L*a*b* values were in the range of L*=25 to 60, a*=5 to 0 and b*=10 to 17.

(6) If not mentioned otherwise, the dwell time for the individual substrates in the respective colorant composition is thirty minutes and is conducted at room temperature (r.t.). The respective sample is then rinsed with water until the excess of colorant is removed, dried and subjected to the CIELAB measurement.

(7) The abbreviation a.t. or r.t. means ambient temperature or room temperature, respectively.

Example 1: Preparation of a Leucoindigo Vat with Sodium Dithionite and Coloring of Yak Hair (State of the Art)

(8) Commercially available plant-based hair colorants are only sold as a herbal powder and meant to be applied as a paste rather than a solution, cream or gel, since this would require the stabilization of the soluble leucoindigo. Thus, an indigo colorant composition normally applied solely to textiles is used for a better comparison.

(9) An aqueous sodium hydroxide solution (3 wt.-%, 50 mL) is added to water (300 mL) and heated to 70 C. in a water bath. Synthetic indigo powder (1 g) is suspended in a mixture of ethanol (96%, 10 mL) with an aqueous sodium hydroxide solution (3 wt.-%, 50 mL) and added to the heated diluted sodium hydroxide solution. After the addition of sodium dithionite (10 g), the reaction mixture is stirred for another 30 minutes at 70 C. before being allowed to cool to room temperature. A color change to yellow is observed over the course of the reaction, indicating the formation of leucoindigo. Moreover, the blueish skin is formed on the surface of the reaction solution.

(10) The samples of the obtained solution are then filled into a glass container with a PE screw cap (sample glass) or airtight aluminum tubes (Al1 and Al2) and stored for a defined period at defined temperature to determine the long-term stability by visual assessment and measurement of the resulting CIELAB values of yak strands colored therewith. The results are summarized in table 1. The term Ref. denotes the untreated yak hair used as reference.

(11) TABLE-US-00001 TABLE 1 Results - long term stability of prior art colorant. t in Sample T weeks L* a* b* E Stability Ref. 81.27 0.59 12.94 fresh r.t. 0 18.81 3.58 12.75 67.53 glass r.t. 1 44.10 4.59 16.38 26.82* Instable Al1 r.t. 4 29.71 1.28 17.84 12.97* Instable Al2 40 C. 4 36.85 5.16 16.14 20.33* Instable *With reference to sample fresh

(12) The coloration of yak hair in presence of sodium dithionite is possible at high pH values right after the preparation (sample fresh), the dyeing vat is not stable under the respective conditions as provided in table 1 above. This is indicated by the large E values, implying a pronounced variation of the shade obtained when using the aged dyeing vat for coloration of yak hair. Moreover, the highly caustic solution excludes an application of the dyeing vat for cosmetic purposes.

Example 2: Preparation of a Leucoindigo Vat in Water Free Organic Solvents

(13) A solution of sodium hydroxide (1.68 g, 42 mmol) in propylene glycol (15.12 g) and a solution of fructose (5.16 g, 28.64 mmol) in propylene glycol (46.44 g) are sequentially added to the stirred suspension of synthetic indigo (5.0 g, 19.06 mmol) in propylene glycol (26.6 g) to create sample 2a. The mixture is heated to 80 C. and stirred for another thirty minutes. After cooling to room temperature, the obtained yellowish-brown solution is filled into airtight containers for storage.

(14) Samples 2b (ethylene glycol), 2c (hexylene glycol), 2d (isopentyldiol) and 2e (dipropylene glycol) are prepared in an analogous manner.

(15) Comparative sample 2f is also prepared in analogous manner to sample 2a. However, aqueous solutions of sodium hydroxide and fructose are used, resulting in a water content of approximately 67 wt.-% of the total weight of the composition.

(16) TABLE-US-00002 TABLE 2 Results - long term stability of samples 2a to 2f. t in Sample T weeks L* a* b* E Stability Brilliance* Ref. 81.27 0.59 12.94 Brilliant 2a a.t. 0 32.20 2.36 15.27 Brilliant 40 C. 12 30.80 1.76 15.30 1.50 Stable Brilliant 2b a.t. 0 20.15 2.12 12.96 Brilliant 40 C. 12 27.20 0.78 13.03 7.17 Suffi- Brilliant ciently stable 2c a.t. 0 33.93 0.77 16.93 Brilliant 40 C. 12 36.52 0.74 14.52 2.67 Stable Brilliant 2d a.t. 0 34.99 0.27 13.88 Brilliant 40 C. 12 37.71 0.84 14.02 2.78 Stable Brilliant 2e a.t. 0 33.46 0.74 13.94 Brilliant 40 C. 12 35.80 2.19 13.80 2.75 Brilliant 2f a.t. 0 36.9 1.91 13.65 Matte 40 C. 4 39.811 2.87 10.5 4.27 Suffi- Matte ciently stable 40 C. 12 58.3 0.54 2.64 26.9 unstable n.a.

(17) The results clearly show that the inventive leucoindigo colorant compositions 2a to 2e achieve excellent coloring results even after extended storage periods at elevated temperatures. For indigo colorants the evaluation of the colorant's stability is predominantly determined by parameter b*, since the b* axis represents the blue-yellow opponents.

(18) In contrast, the vatting is incomplete for comparative sample 2f, which resulted in a correspondingly high amount of precipitated indigo and less brilliant shades, (optically visible to the evaluation panel). This suggests a deposit of insolubilized indigo on the strands. The twelve weeks old dyeing vat does not color the yak hair any more, but only leads to a soiling of the strands. Therefore, an increased water content leads to instability,

Example 3: Attempted Preparation of a Leucoindigo Dyeing Vat with 1,3-Propanediol

(19) Finely powdered sodium hydroxide (0.17 g, 4.2 mmol) and a 10% solution of fructose in 1,3-propanediol (2.9 mmol, 5.16 g) are sequentially added to a stirred suspension of synthetic indigo powder (0.5 g, 1.91 mmol) in 1,3-propanediol (2.7 g). The mixture is then heated to a temperature of 100 C.

(20) In contrast to example 2, no usable dyeing vat is obtained even after 60 minutes of stirring at 100 C., which shows, that an organic solvent of the second group solvent requires the presence of a first group organic solvent and/or water.

Example 4: Attempted Preparation of a Leucoindigo Dyeing Vat with Glycerol

(21) Finely powdered sodium hydroxide (0.17 g, 4.2 mmol) and a 10% solution of fructose in glycerol (2.9 mmol, 5.16 g) are added sequentially to a stirred suspension of synthetic indigo powder (0.5 g, 1.91 mmol) in glycerol (2.7 g). The mixture is heated to a temperature of 100 C.

(22) In contrast to example 2, no usable dyeing vat is obtained even after 60 minutes of stirring at 100 C.

Example 5: Preparation of a Leucoindigo Dyeing Vat with an Organic-Aqueous Solvent Mixture

(23) A 30% solution of sodium hydroxide in water (45 mmol, 6.0 g) and fructose (7.0 g, 38.85 mmol) are sequentially added to the stirred suspension of synthetic indigo powder (3.5 g, 13.35 mmol) in glycerol (60 g) and water (23.5 g). The obtained mixture is heated to 80 C. and stirred for another 30 minutes. After cooling to room temperature, the obtained yellowish-brown solution is filled into airtight containers for storage. The dye-out after 4 weeks stored at 40 C. showed complete discoloration on the dyed yak strands:

(24) TABLE-US-00003 TABLE 3 Results - long term stability of example 5 t in Sample T weeks L* a* b* E Stability Ref. 81.27 0.59 12.94 5 a.t. 0 37.54 2.16 13.16 40 C. 4 62.30 6.64 18.55 31.71 unstable

(25) A comparison of examples 4 and 5 shows that the addition of water to second group solvents such as glycerol is necessary to obtain a usable leucoindigo dyeing vat resulting in a higher solubility of the lecuoindigo in the vat solution. However, adding water brings in the disadvantage of entrapped oxygen thus resulting in poor longterm stability. Group 2 solvents such as glycerin cannot be used without group 1 solvents in combination with water.

Example 6a: Preparation of a Leucoindigo Dyeing Vat Using Natural Indigo with a Propylene Glycol/Water Mixture

(26) A 10% solution of sodium hydroxide in water (48.25 mmol, 19.3 g), fructose (5.1 g, 28.31 mmol) and sodium dithionite (1.67 g, 9.59 mmol) are sequentially added to the stirred suspension of natural indigo (indigo content: 54%, ash content: 6.3%, 5.0 g, 10.29 mmol) in propylene glycol (38.93 g) and water (10.0 g). The obtained mixture is heated to 80 and stirred for another 30 minutes. After cooling to room temperature, the obtained ground solution is filled into airtight containers for storage.

Example 6b: Preparation of a Leucoindigo Dyeing Vat Using Synthetic Indigo with a Propylene Glycol/Water Mixture

(27) A solution of sodium hydroxide (1.18 g, 31.6 mmol) in propylene glycol (18.82 g) and fructose (4.81 g, 26.64 mmol) are sequentially added to the stirred suspension of synthetic indigo (3.5 g, 13.34 mmol) in propylene glycol (41.69 g) and water (30.0 g). The obtained mixture is heated to 80 C. and stirred for another 30 minutes. After cooling to room temperature, the obtained ground solution is filled into airtight containers for storage.

(28) TABLE-US-00004 TABLE 4 Results - long term stability of examples 6a and 6b. t in Sample T weeks L* a* b* E Stability Ref. 81.27 0.59 12.94 6a a.t. 0 49.59 6.07 10.86 40 C. 12 52.57 5.73 11.03 3.00 Stable 6b a.t. 0 22.19 0.90 12.77 40 C. 12 27.27 2.74 12.96 5.10 Stable

(29) Dyeing vats 6a and 6b achieve an intense deep blue color, showing that synthetic and natural indigo can be used as leucoindigo precursor. Moreover, the long-term stability of the leucoindigo vats is not affected by the presence of water.

Example 7a: Preparation of an Alkaline Lawsone-Based Composition in Water-Free Organic Solvents

(30) A 30% solution of sodium hydroxide in propylene glycol (10.35 mmol, 1.38 g) is added to a stirred solution of synthetic lawsone (0.5 g, 2.87 mmol) in propylene glycol (48.12 g) at room temperature. The solution is stirred for another 30 minutes before being filled into airtight containers for storage.

(31) Further alkaline lawsone-based compositions based on isopentyldiol, ethylene glycol, dipropylene glycol, hexylene glycol and propylene glycol are prepared in an analogous manner.

(32) Alternatively, an alkaline lawsone-based composition is obtained from powdered henna leaves by extracting the leaves (10.0 g, 1.45 wt.-% lawsone) with a 10% solution of sodium hydroxide in propylene glycol (12.0 g) at room temperature.

Example 7b: Preparation of an Alkaline Lawsone-Based Composition in an Organic Solvent/Water Mixture

(33) A 30% solution of sodium hydroxide in water (3.86 g) and synthetic lawsone (1.4 g, 8.04 mmol) are added sequentially to a stirred solution of propylene glycol (54.4 g) and water (40 g) at room temperature. The mixture is stirred for another 30 minutes. The resulting solution has a pH value of 12.2 and is filled into airtight containers for storage.

(34) Similar alkaline lawsone-based compositions based on isopentyldiol, ethylene glycol, dipropylene glycol, hexylene glycol and propylene glycol are prepared in an analogous manner.

(35) Alternatively, a similar alkaline lawsone-based composition is obtained from powdered henna leaves by extracting the leaves (10.0 g, 1.45 wt.-% lawsone) with a 30% solution of sodium hydroxide in Water (3.86 g) at room temperature.

Example 7c: Preparation of a pH-Neutral Lawsone-Based Composition in Water Free Organic Solvents

(36) Synthetic lawsone (1.0 g) is added to propylene glycol (99 g) and stirred at ambient conditions until complete dissolution. The obtained solution is filled into airtight containers for storage.

(37) Similar pH-neutral lawsone-based compositions based on isopentyldiol, ethylene glycol, dipropylene glycol, hexylene glycol and propylene glycol are prepared in an analogous manner.

(38) Alternatively, a similar water-free lawsone-based composition is obtained from powdered henna leaves by extracting the leaves (10.0 g, 1.45 wt.-% lawsone)

Example 8: Preparation of Exemplary Aqueous Compositions (Second Constituent)

(39) TABLE-US-00005 TABLE 5 Exemplary aqueous compositions. 8a 8b 8c Pos. INCI/CTFA-name % (w/w) % (w/w) % (w/w) 1 Aqua (water) 85.5 85.5 88.0 2a Xanthan gum 1.5 2b Caesalpinia spinosa gum 1.5 3 Propylene glycol 10.0 10.0 10.0 4 Phenoxyethanol and 1.0 1.0 1.0 ethylhexylglycerin [ 5 Benzyl alcohol 1.0 1.0 6 Citric acid 1.0 1.0 1.0

(40) Components 1 to 6 are mixed under stirring at 80 C. (8a, 8b) and room temperature (8c), respectively. After cooling, compositions with an aqueous (8c) or gel-like (8a, 8b) consistency are obtained. The measured pH-value for gels 8a and 8b is 2.5, whereas the pH value of solution 8c is 2.8.

Example 9: Preparation of a Leucoindigo Based Colorant Cream

(41) TABLE-US-00006 TABLE 6 Ingredients - colorant cream. Pos. INCI/CTFA-name % (w/w) 1 Aqua (water) 20.00 2 Propylene glycol 2.00 3 Xanthan gum 0.40 4 Cetearyl alcohol (and) dicetyl phosphate 6.00 (and) ceteth-10 phosphate [Crodafos CES] 5 Ceteareth-25 0.20 6 Cetearyl alcohol 6.00 7 Lauryl alcohol 3.00 8 Myristyl alcohol 1.00 9 Pentaerythritol 0.20 10 Paraffinum Liquidum (Mineral Oil) 1.00 11 Aqua (Water) 13.99 12 Sodium hydroxide 0.83 13 Sodium Hydrosulfite 0.30 14 Propylene Glycol 40.00 15 Indigo 2.50 16 Fructose 2.58

(42) Compounds 1 to 3 are heated to 80 C. under stirring until a homogenous solution was obtained. Compounds 9 and 10 is added to a stirred mixture of compounds 4 to 8 at 80 C. Subsequently, the mixture of compounds 4 to 10 is added to the solution comprising compounds 1 to 3 to form the cream-basis. The mixture of compounds 11 to 16 is heated to 80 C. and stirred for an additional 30 minutes at this temperature. The obtained yellowish-brown solution is added to the cream-basis comprising compounds 1 to 10 at 80 C. After cooling to room temperature, the cream is filled into airtight containers for storage.

Example 10: Optimization of the Coloration of Keratin Fibers

(43) To determine the optimal coloration result, a serial dilution of composition 2a with an aqueous composition (pure water) with ratios ranging from 1:1 to 1:10 is prepared. The pH value of each dilution is adjusted to 4.3 by addition of citric acid. The results are summarized in table 6.

(44) TABLE-US-00007 TABLE 7 Coloration results - serial dilution. Sample ratio pH L* a* b* E Ref. 81.27 0.59 12.94 10a 1:1 4.3 37.83 1.84 14.36 51.32 10b 1:2 4.3 39.42 2.05 13.73 49.64 10c 1:3 4.3 37.68 1.95 13.66 51.08 10d 1:5 4.3 34.64 2.09 15.27 54.52 10e 1:7 4.3 39.98 2.46 13.12 48.86 10f 1:10 4.3 38.93 2.17 13.04 49.70

(45) Taking the measuring tolerances on the uneven fiber surface into account the b*-values remain approximately constant over the whole series. However, the L* value for dilution 10d with a coloring to aqueous composition ratio of 1:5 is considerably lower than the other L* values measured in the series, i.e. showing the most intense color (lowest lightness). In combination with the highest measured b* value, i.e. the highest proportion of blue, and consequently, largest color change E, the coloration resulting from dilution 10d is superior to the rest and therefore best suited for the further coloration processes.

Example 11: Coloration of Keratin Fibers with a Three-Constituent Mixture (Gel 8a)

(46) The possible color shades of a three-constituent mixture are screened by varying the ration of the eucoindigo based composition 2a and the lawsone based composition 7a. The ratio of the colorant composition (mixture) to the aqueous composition 8a is kept at the optimized ratio of 1:5 (w/w). The results are summarized in table 7:

(47) TABLE-US-00008 TABLE 8 Color shades - three-constituent mixture (gel 8a). Sample 2a 7a pH L* a* b* E Shade Ref. 81.27 0.59 12.94 beige 11a 0% 100% 3.3 63.24 25.63 44.13 44.55 Henna-red 11b 20% 80% 3.4 52.94 4.77 17.34 23.74 Reddish brown (fawn) 11c 80% 20% 4.1 41.18 3.84 6.80 44.80 Reddish mid brown 11d 100% 0% 4.1 47.11 3.26 12.33 48.17 Medium-dark jeans- blue

(48) Similar results are obtained, when using composition 8b instead of composition 8a as second constituent and/or different organic solvents for the leucoindigo based and/or lawsone-based colorant compositions, e.g., compositions 2b to 2e. Storing the individual constituents separately over a three-month period in a warming cabinet at 40 C. does not or hardly impair the coloration result of colorant mixtures prepared therewith.

Example 12: Coloration of Keratin Fibers with a Three-Constituent Mixture (Liquid 8c)

(49) In analogy to example 11, the possible color shades are screened using the liquid composition 8c as aqueous component. The results are summarized in table 8:

(50) TABLE-US-00009 TABLE 9 Color shades - three-constituent mixture (liquid 8c). Sample 2a 7a pH L* a* b* E Shade Ref. 81.27 0.59 12.94 beige 12a 0% 100% 3.2 57.35 29.57 54.94 56.97 Henna-red 12b 10% 90% 3.2 40.32 4.77 26.88 43.59 Reddish brown (fawn) 12c 20% 80% 3.2 37.68 3.60 23.23 44.72 Reddish mid brown 12d 30% 70% 3.2 33.63 2.72 19.20 48.17 Slightly reddish mid brown 12e 40% 60% 3.2 34.27 6.61 25.12 49.08 Mid brown 12f 50% 50% 3.2 34.87 0.86 16.26 46.54 Dark brown 12g 60% 40% 3.2 32.44 1.86 10.02 48.94 Dark ashen brown 12h 70% 30% 3.2 35.52 2.89 0.47 47.73 Black brown ashen 12i 80% 20% 3.3 35.60 2.71 2.10 48.13 Black brown ashen 12j 100% 0% 3.3 33.26 1.61 12.49 54.34 Intense dark blue

(51) Similar results are obtained when using different organic solvents for the leucoindigo based and/or lawsone-based colorant compositions, e.g., compositions 2b to 2e. The comparison to the shades obtained in examples 11 and 12 shows, that that either with gel-like or with liquid consistency, a full range of color starting from henna red up to indigo blue has been achieved.

(52) Storing the individual constituents separately over a three-month period in a warming cabinet at 40 C. does not or hardly impair the coloration result of colorant mixtures prepared therewith.

Example 13: Coloration of Keratin Fibers with a Three-Constituent Mixture Comprising Composition 6b (Gel 8a)

(53) The obtainable color shades for leucoindigo colorant compositions comprising a water/organic solvent mixture are screened in analogy to example 11. The results are summarized in table 10.

(54) TABLE-US-00010 TABLE 10 Color shades - three-constituent mixture (gel 8a). Sam- ple 6a 7a pH L* a* b* E Shade Ref. 81.27 0.59 12.94 beige 13a 0% 100% 3.3 54.36 25.67 47.47 51.04 Henna-red 13b 30% 70% 3.4 46.87 17.34 36.67 45.47 Slightly brownish henna-red 13c 50% 50% 3.6 43.35 16.28 33.15 46.16 Brownish henna-red 13d 60% 40% 3.8 46.69 7.29 22.99 36.86 Red brown 13e 70% 30% 4.1 44.05 9.53 24.86 40.37 Dark red brown 13f 80% 20% 4.1 46.20 5.95 20.36 36.46 Brown 13g 90% 10% 4.1 40.63 0.34 8.37 40.96 Ashen brown 13j 100% 0% 4.1 41.80 4.19 9.73 45.66 Intense dark blue

(55) Similar results are obtained, when using composition 8b instead of composition 8a as second constituent and/or different organic solvents for the leucoindigo based and/or lawsone-based colorant compositions.

(56) Storing the individual constituents separately over a three-month period in a warming cabinet at 40 C. does not or hardly all impair the coloration result of colorant mixtures prepared therewith.

Example 14: Coloration of Keratin Fibers with Leucoindigo Colorant Cream 9

(57) The leucoindigo colorant cream 9 is mixed with different aqueous compositions in a ratio of 1:5. The obtained mixture is applied to yak hair (6 g of mixture per gram yak hair). Prior to the CIELAB measurement, the hair is rinsed and dried after the application time of 15 minutes. The results are summarized in table 11.

(58) TABLE-US-00011 TABLE 11 Color shades - colorant cream. Sample Aq. comp. pH L* a* b* E Shade Ref. 81.27 0.59 12.94 beige 14a Propylene 4.3 54.36 25.67 47.47 51.04 Light glycol/water 1:1 jeansblue 14b Water 4.3 46.87 17.34 36.67 45.47 Light jeansblue 14c Gel 8a 4.2 43.35 16.28 33.15 46.16 Light jeansblue

(59) The obtained blue shades are similar for all samples. Thus, it could be shown, that uniform coloring results are also reliably achieved for colorant creams with different aqueous compositions and organic solvent to water ratios. Similar results are obtained with colorants based on other organic solvents.

Example 15: Coloration of Fabrics with an Alkaline Leucoindigo Colorant

(60) The coloration is tested on SDCE Multifibre DW from SDC Enterprises Ltd, GB. The fabric strips contain different textile materials for performing color fastness tests according to ISO 105, group C and group E.

(61) Leucoindigo composition 2a is diluted with water as aqueous constituent in a 1:5 ratio. The pH value of the resulting dyeing solution is 10.9. For the coloration, 10 g of the test fabric (SDCE Multifibre DW) is treated with 250 g of the dyeing solution for 30 minutes, followed by rinsing with water and drying. The results for the individual fibers/fabrics at different temperatures are summarized in table 12.

(62) TABLE-US-00012 TABLE 12 Results - alkaline coloration of textiles. Sample L* a* b* E Shade Wool ref. 89.06 2.69 9.62 Beige dyed at 20 C. 33.06 0.23 13.40 60.62 Mid jeansblue dyed at 70 C. 26.42 1.66 12.03 66.42 Black blue Polyacryl Orion 75 ref. 92.26 2.29 2.19 White dyed at 20 C. 59.08 1.66 9.68 35.24 Light greyish blue dyed at 70 C. 46.47 0.15 8.99 47.18 Mid greyish blue Polyester Dacon 54 ref. 90.88 1.50 0.56 White dyed at 20 C. 48.69 0.72 12.89 44.29 Ashen jeansblue dyed at 70 C. 30.72 1.95 13.66 61.91 Dark ashen jeans- blue Polyamid Nylon 6.6 ref. 92.14 2.19 1.68 White dyed at 20 C. 42.04 0.27 15.55 53.01 Jeansblue dyed at 70 C. 27.47 1.58 18.05 67.72 Intense jeansblue Cotton ref. 91.42 2.00 5.61 Beige dyed at 20 C. 19.54 3.88 14.71 74.93 Very dark jeansblue dyed at 70 C. 28.45 1.69 13.16 65.81 Dark jeansblue Celluoseacetate ref. 92.05 3.06 5.87 Beige dyed at 20 C. 42.53 1.55 16.19 54.23 Very light jeansblue dyed at 70 C. 31.71 1.99 16.13 64.42 Light jeansblue

(63) The obtained shade varies with the respective fiber/fabric. As expected, a higher dyeing temperature results in a color intensification for all samples. Similar results are obtained with colorants based on other organic solvents.

Example 16: Coloration of Fabrics with an Acidic Leucoindigo Colorant

(64) The coloration is tested on SDCE Multifibre DW from SDC Enterprises Ltd, GB. The fabric strips contain different textile materials for performing color fastness tests according to ISO 105, group C and group E.

(65) leucoindigo composition 2a is diluted with the liquid aqueous composition 8c in different ratios (see column sample/ratio in table 12). The pH value of the resulting dyeing solutions is 3.0. The fabrics are immersed in the dyeing solutions at 85 C. for 15 minutes in the respective liquor ratios (column I.r.), i.e., the ratio of grams fabric to grams dyeing solution, as indicated below. The fabric samples are subsequently rinsed with water and dried prior to measuring their color.

(66) TABLE-US-00013 TABLE 13 Results - acidic coloration of textiles. Sample/ratio I.r. L* a* b* E Shade Wool ref. 89.06 2.69 9.62 Beige 1:10 1:25 34.43 3.54 19.49 62.21 Dark jeans- blue 1:10 1:10 26.58 0.96 10.53 65.75 Dark jeans- blue 1:50 1:25 22.33 0.85 7.17 68.90 Dark jeans- blue 1:200 1:25 39.83 3.08 1.20 49.94 Bluegreen Polyacryl Orion 75 ref. 92.26 2.29 2.19 White 1:10 1:25 34.12 4.83 21.24 63.08 Vibrant blue 1:10 1:10 46.01 0.78 16.49 49.90 Steelblue 1:50 1:25 35.63 0.69 22.45 61.82 Vibrant blue 1:200 1:25 62.02 3.80 6.71 31.56 Very light jeansblue Polyester Dacon 54 ref. 90.88 1.50 0.56 White 1:10 1:25 42.03 0.18 12.85 50.67 Steelblue 1:10 1:10 45.60 1.84 14.40 47.68 Steelblue 1:50 1:25 53.42 2.65 13.09 39.88 Steelblue 1:200 1:25 63.18 2.18 4.37 28.14 Light grey- blue Polyamid Nylon 6.6 ref. 92.14 2.19 1.68 White 1:10 1:25 16.31 4.79 2.50 76.26 Very dark black blue 1:10 1:10 17.30 4.96 7.32 75.72 Very dark black blue 1:50 1:25 16.11 3.64 3.28 76.42 Very dark black blue 1:200 1:25 21.14 0.54 15.69 73.11 Mid jeans- blue Cotton ref. 91.42 2.00 5.61 Beige 1:10 1:25 35.43 0.03 12.89 59.00 Ashen jeans- blue 1:10 1:10 34.02 0.12 12.89 60.34 Ashen jeans- blue 1:50 1:25 41.20 1.75 11.98 53.21 Ashen jeans- blue 1:200 1:25 53.59 1.97 7.06 39.89 Light grey- blue Celluoseacetate ref. 92.05 3.06 5.87 Beige 1:10 1:25 25.55 1.85 8.36 68.18 Very dark jeansblue 1:10 1:10 20.15 5.54 12.93 74.81 Very dark jeansblue 1:50 1:25 20.04 3.02 8.43 73.66 Very dark jeansblue 1:200 1:25 37.46 1.05 17.23 59.31 Steelblue

(67) Similar to the alkaline dyeing solutions of example 15, different shades are obtained for different fabrics. Surprisingly, even a high dilution ratio of 1:200 leads to a clearly visible coloration of the individual fabrics, proofing the exceptional dyeing capacity of the inventive colorant. Similar results are obtained with colorants based on other organic solvents.

Example 17: Coloration of Silk with Acidic or Alkaline Leucoindigo Colorants

(68) The leucoindigo colorant composition 2a is diluted with pure water as aqueous constituent in a ratio of 1:5 and applied to the silk. The pH value of the colorant solution is 10.9.

(69) The acidic leucoindigo colorant solution is prepared in the same manner, however, the pH value was adjusted to 3.0 with citric acid.

(70) The coloration process is carried out by immersing the silk in the colorant solution at a ratio of 1 g fabric per 100 g solution at 60 C. for 30 minutes] The silk samples are subsequently rinsed and dried prior to measuring their CIELAB values.

(71) TABLE-US-00014 TABLE 14 Results - acidic coloration of textiles. Sample/ratio I.r. L* a* b* E Shade silk ref. 94.02 1.65 1.71 White alkaline 1:100 32.65 0.68 13.94 63.34 Light jeansblue acidic 1:100 26.81 1.77 7.62 67.85 Black blue

(72) The obtained CIELAB values show, that a coloration under acidic conditions yields superior results in terms of color intensity. Moreover, the obtained coloration is more uniform at low pH. Similar results are obtained with colorants based on other organic solvents.

(73) This observation is consistent with the hypothesis that coloration results is impaired due to repulsive electrostatic forces between leucoindigo and the respective substrate fibers at high pH values.