LOW TEMPERATURE COLOURING METHOD

Abstract

The present invention relates to a method of colouring polymer substrates at low temperatures. The method comprises subjecting the polymer substrate that is to be coloured to a colouring liquor comprising a solvent in which the colourant has a high solubility and then adding a solvent in which the colourant has a low solubility, typically water.

Claims

1. A method of colouring a polymer substrate, the method comprising: a) subjecting the polymer substrate to a colouring liquor at a temperature T1, T1 being below 100 C., said colouring liquor comprising at least one colourant dissolved in a first solvent system to provide the polymer substrate wetted with the colouring liquor; b) adding a second solvent system to the polymer substrate wetted with the colouring liquor, without raising the temperature above a temperature T2, T2 being below 100 C., to provide the coloured polymer substrate wetted with a mixture of the first solvent system and the second solvent system; and c) separating the coloured polymer substrate from the mixture of the first and second solvent systems and any remaining colourant; wherein the colourant or colourant dye is more soluble in the first solvent system than in the second solvent system.

2. (canceled)

3. (canceled)

4. A method of claim 1, wherein the second solvent system is water.

5. A method of claim 1, wherein the first solvent system and the second solvent system are miscible.

6. (canceled)

7. A method of claim 1, wherein the first solvent system is a polar organic solvent or a mixture of polar organic solvents.

8. A method of claim 7, wherein the first solvent system comprises acetone.

9. A method of claim 7, wherein the first solvent system comprises a solvent selected from glycerol, ethylene glycol diacetate (EGD), triethylene glycol monomethyl (TGM), dipropylene glycol methyl ether (DME) and 1-methoxy-2-propanol.

10. A method of claim 1, wherein the polymer substrate is a fibre substrate.

11. A method of claim 10, wherein the fibre substrate comprises fibres selected from: a polyester, nylon, a polyurethane, wool, silk, cotton or a mixture thereof.

12. A method of claim 11, wherein the fibre substrate comprises polyester fibres.

13. A method of claim 12, wherein the fibre substrate comprises polyester fibres and at least one fibre selected from cotton, regenerated cellulose, wool, silk, polyamide, a different polyester, polyvinylchloride, polyacrylonitrile, mohair, cashmere and a polyurethane.

14. A method of claim 13, wherein the fibre substrate comprises a material that is a blend of polyester fibres and at least one fibre selected from cotton, regenerated cellulose, wool, silk, polyamide, a different polyester, polyvinylchloride, polyacrylonitrile, mohair, cashmere and a polyurethane.

15. A method of claim 14, wherein the fibre substrate comprises a first material that comprises polyester fibres and a second material that comprises at least one fibre selected from cotton, regenerated cellulose, wool, silk, polyamide, a different polyester, polyvinylchloride, polyacrylonitrile, mohair, cashmere and a polyurethane.

16. A method of claim 15, wherein the fibre substrate is a whole garment.

17. A method of claim 1, wherein the ratio of the total volume of the first solvent system to the total volume of the second solvent system is in the range 1:2 to 1:20.

18. A method of claim 16, wherein the ratio of the total volume of the first solvent system to the total volume of the second solvent system is in the range 30:70 to 10:90.

19. A method of claim 1, wherein the weight ratio of the polymer substrate to the first solvent system is in the range from 3:1 to 1:3.

20. A method of claim 1, wherein the at least one colourant is at least one dye.

21. A method of claim 20, wherein the at least one dye is a disperse dye.

22. A method of claim 1, wherein the method comprises dissolving the at least one colourant in the first solvent system to form the colouring liquor

23. A method of claim 1, wherein the colouring liquor does not comprise a dispersing agent.

24. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0111] Embodiments of the invention are further described hereinafter with reference to the accompanying drawings, in which:

[0112] FIG. 1 shows the high temperature (HT) PES dyeing method used as a comparator in the Examples below;

[0113] FIG. 2 shows the reduction clearing process employed for the Examples;

[0114] FIG. 3 provides a general depiction of controlled precipitation dyeing method of the invention;

[0115] FIG. 4 shows the colour strength of 2% omf dyeings on PES achieved using controlled precipitation method of the invention; Teratop Yellow HL-G 150%; 120 mins at 98 C.;

[0116] FIG. 5 shows the colour strength of 2% omf dyeings on PES achieved using controlled precipitation method of the invention; Teratop Yellow HL-G 150%; 30, 60 and 90 at 98 C.;

[0117] FIG. 6 shows the colour strength of 2% omf dyeings on PES achieved using controlled precipitation method of the invention for 20 mins at 98 C.; Teratop Yellow HL-G 150%;

[0118] FIG. 7 shows the colour strength of 2% omf dyeings on PES achieved using controlled precipitation method of the invention for 120 mins at 85 C.; Teratop Yellow HL-G 150%;

[0119] FIG. 8 shows the colour strength of 2% omf dyeings on PES achieved using controlled precipitation method of the invention for 20 mins at 98 C. (Teratop Blue HL-G 150%: left and Teratop Pink HL-G 150%: right);

[0120] FIG. 9 shows the dyeing method used for the dyeing methods described in Examples 3, 4 and 5;

[0121] FIG. 10 shows the colour strength of 2% omf dyeing of crude grade Teratop Yellow HL-G 150% on a fabric composite comprising polyester fabric attached to scoured PA 66 fabric;

[0122] FIG. 11 shows the colour strength of 2% omf dyeings of commercial Teratop Yellow HL-G 150% on PES as a function of dyeing temperature using DMSO as solvent

DETAILED DESCRIPTION

[0123] Organic solvents are organic compounds that are liquids at room temperature and atmospheric pressure. Typically, organic solvents are compounds that comprise both carbon atoms and hydrogen atoms. One exception to this is carbon tetrachloride. Organic solvents may also comprise oxygen, nitrogen, chlorine, fluorine or sulphur.

[0124] The term wetted is used in this specification to mean that the polymer (e.g. fibre) substrate is in contact with a liquid, e.g. the dye liquor or the mixture of the first solvent system and the second solvent system. It may mean that the substrate (e.g. fibre substrate) is soaked in the liquid, e.g. saturated with the liquid. It may mean that the substrate (e.g. fibre substrate) is coated in the liquid. It may mean that the substrate (e.g. fibre substrate) is immersed in the liquid. Other techniques that could be used include spraying, soaking, vapourisation, imbibition, etc.

[0125] The polymer (e.g. fibre) substrate is described as coloured where the colourant molecules have become absorbed into the substrate (e.g. into the fibres). Throughout the description and claims of this specification, the words comprise and contain and variations of them mean including but not limited to, and they are not intended to (and do not) exclude other moieties, additives, components, integers or steps. Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

[0126] Features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

[0127] The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

EXAMPLES

General Methods

Materials

[0128] Scoured poly(ethylene terephthalate) (PES) fabric (120 gm.sup.2), scoured, bleached and mercerised woven cotton fabric (180 gm.sup.2) and scoured PA 66 fabric (116 gm.sup.2) was obtained from Whaleys (Bradford, UK). Commercial grade as well as crude grade (ie as-synthesised) samples of three disperse dyes, namely Teratop Yellow HL-G 150%, Teratop Blue HL-G 150% and Teratop Pink HL-G 150% were kindly provided by Huntsman (Switzerland). Commercial dyes were used in this work so as to reflect commercial dyeing practice whilst equivalent crude grade dyes were also used to determine whether it would be possible to dye PES using dispersant-free disperse dyes. The three dyes used were chosen arbitrarily as being representative of modern commercial disperse dyes. A 2% omf depth of shade was used for each of the three dyes as this provided typical pale/medium depth dyeings.

[0129] Samples of Polysorbate 20, Polysobate 60, Polysorbate 80, Lecithin and Superclean were obtained from Sigma-Aldrich. All other chemicals were of general purpose grade.

[0130] From measured values of the relative dye contents of the respective pairs of commercial grade and crude grade dye samples, the amount of crude grade dye employed in dyeing was adjusted so that the depth of shade obtained (ie 2% omf) was the same as that secured using the commercial grade dye, was obtained.

Comparative General Method

[0131] The high temperature (HT) dyeing method used for comparison in this work is shown in FIG. 1.

[0132] The PES fabric (5 g or 10 g) was dyed using both the commercial grade and grade crude disperse dyes following the procedure shown in FIG. 1. At the end of dyeing, the dyed sample was removed from the dyebath, squeezed to remove surplus dye liquor and rinsed in water according to the procedure depicted in FIG. 1. The dyed sample was then squeezed once more and subjected to the reduction clear procedure displayed in FIG. 2. At the end of the reduction clearing process the sample was removed, squeezed to remove surplus liquor and rinsed in cold water as shown in FIG. 2. The reduction cleared dyeing was squeezed and allowed to dry in the open air.

General Method of the Invention

[0133] The controlled precipitation method of the invention is illustrated in a general sense in FIG. 3.

Example 1Development of the Methodology Using Disperse Dyes, PES and Acetone

[0134] The method depicted in FIG. 3 was carried out with a.sub.1; a.sub.2; a.sub.3; a.sub.4=10 cm.sup.3 water; t.sub.1=30; t.sub.2=30; a.sub.3=30; a.sub.4=30; x=98 C.

[0135] The disperse dye was dissolved in a given volume (in this case 10 cm.sup.3) of acetone and the ensuing solution was applied to the PES fibre.

[0136] When the temperature of the dyebath reached 98 C., a volume (10 cm.sup.3) of water was added and dyeing continued for a certain period of time, after which a further 10 cm.sup.3 of water was added. This process continued until the final dyebath volume was 50 cm.sup.3, corresponding to a 1:10 liquor ratio. Thus, over the length of the dyeing process, the ratio of water:acetone was gradually increased from 0:100 at the start of dyeing to 80:20 at the end of dyeing.

[0137] Without wishing to be bound by theory, the purpose of progressively introducing water to the acetone dye solution was to gradually force the disperse dye to precipitate out of solution in a controlled manner, so as to achieve increased dye-fibre substantivity and, thus, increased dye uptake, in a controlled and measured manner.

[0138] Following the procedure just described, the total dyeing time at 98 C. was 120 mins. FIG. 4 reveals that using this approach, the ensuing dyeing displayed very high colour strength, which was considerably greater than that secured using the commercial grade dye and the conventional HT dyeing method at 130 C. Visual inspection revealed that the dye precipitation method of the invention not only provided a deeper depth of shade than the HT method but, significantly, the level of dyebath exhaustion secured was much greater.

[0139] Thus the higher colour strength of the 120 mins 98 C. dyeing (FIG. 4) can be attributed to the greater extent of dye exhaustion achieved. The fact that the residual dyebath was essentially free of unexhausted disperse dye offers obvious cost and environmental potential. In other words, in order to achieve a colour strength that is equivalent to that furnished using a commercial grade dye employing a conventional 2% omf dyeing method at 130 C. (ie an f.sub.k value of 50) will require less disperse dye, if the controlled precipitation dyeing method of the invention is used (ie 1.25% omf dye), because virtually 100% dye exhaustion is achieved. Furthermore, because crude grade disperse dye was used for the precipitation dyeing method of the invention, then the exhausted dyebath will contain essentially no dye, zero dispersing agent and zero levelling agent, compared to the residual dyebath that will ensue from the conventional HT dyeing method.

[0140] Attempts were made to reduce the length of dyeing time at 98 C.; for this, in FIG. 3, a.sub.1, a.sub.2, a.sub.3 and a.sub.4=10 cm.sup.3 water and the total time at the commercial boil was 90 min, 60 min and 30 min (in all cases a.sub.1=a.sub.2=a.sub.3=a.sub.4. As FIG. 5 shows, reducing the dyeing time at 98 C. did not affect the colour yield of the ensuing dyeings; a comparison of FIGS. 4 and 5 shows that the colour yields of all four dyeings were the same.

[0141] When the total time at the commercial boil was further reduced to 20 mins (ie, a.sub.1, a.sub.2, a.sub.3 and a.sub.4=10 cm.sup.3 water and a.sub.1=a.sub.2=a.sub.3=a.sub.4=5) the colour strength of the dyed fabric was similar to that achieved for dyeing times of 30, 60, 90 and 120 mins (FIG. 6). However, with further reduction of dyeing time at the commercial boil the colour strength of the dyeings reduced.

[0142] When the temperature of dyeing was lowered from 98 C. to 85 C., it was found (FIG. 7) that whilst the colour strength of dyeings carried out for 120 min were the same as those achieved at 98 C., shorter dyeing times at 85 C. of 60 min and 90 min produced dyeings that were of lower colour strength. As observed for dyeings undertaken at the commercial boil, the residual dyebath obtained after 120 min at 85 C. was observed on visual inspection to be devoid of dye.

[0143] When two other disperse dyes, namely Teratop Blue HL-G 150% and Teratop Pink HL-G 150%, were applied to PES using the precipitation dyeing method of the invention for 20 min at 98 C., and the colour strengths of the dyeings were compared to those secured using the HT dyeing method (ie at 130 C.) are shown in FIG. 8.

[0144] It is apparent that for each of the dyes, higher colour strength dyeings were achieved using the precipitation dyeing method of the invention at 98 C. (FIG. 8) and, also, that the extent of dye exhaustion observed, was much higher for the HT dyeing method.

Example 2Fastness

[0145] Table 1 shows that 2% omf dyeings obtained using the three commercial grade dyes when applied using the HT method (i.e. 130 C.) displayed very good fastness to washing at 60 C., as expected; visual inspection also showed the impressive depths of shade of the dyeings after wash fastness testing. The results presented in Table 1 also reveal that the corresponding dyeings which had been produced using crude grade samples of the three dyes employing the precipitation dyeing method of the invention at 98 C. for 20 min displayed essentially the same high level of wash fastness. The latter findings are impressive when it is recalled that the colour strength of the 98 C. dyeings were much greater than that of their 130 C. counterparts. Thus, as expected, the manner by which the disperse dyes were applied (ie differences in dyeing temperature, dyeing duration and acetone) had no effect on wash fastness.

TABLE-US-00001 TABLE 1 fastness of 2% omf dyeings on PES produced using the HT method (commercial grade dyes at 130 C.) and 20 min precipitation method of the invention at 98 C., to ISO 105-C06/C2S (60 C.) Teratop HL- dyeing change bleached G 150% grade temp/ C. in shade wool acrylic polyester polyamide cotton Diacetate Yellow commercial 130 5 5 5 5 4/5 5 4.5 crude 98 5 5 5 5 4.5 5 4.5 Blue commercial 130 4/5 4/5 5 4 5 5 4/5 crude 98 4/5 4/5 5 4 4/5 5 4/5 Pink commercial 130 5 4 5 4 4/5 5 4/5 crude 98 5 4 5 4 4/5 5 4/5

[0146] When the above method was followed but using polyester fabric which had been previously wetted-out using water and squeezed to remove surplus water, the colour strength of the ensuing dyeing obtained for 20 min at 98 C. was comparable to that achieved using dry polyester fabric.

Example 3Other Fabrics and Other Classes of Dyes

[0147] The methods of the invention can also be used to dye other substrates using other dye types. The following example describes the dyeing of wool, silk and polyamide substrates with acid dyes and a disperse dye.

[0148] The general method used throughout this example is shown in FIG. 9. A Roaches Pyrotec S dyeing machine) was used. 0.1 g of commercial dye was dissolved in 10 cm.sup.3 acetone and the ensuing solution was placed in a 300 cm.sup.3 capacity dye tube, followed by 5 g of fabric. The sealed dye tube was heated to 85 C. and then 10 cm.sup.3 of water was injected into the dyeing tube. A further total of 40 cm.sup.3 of water was injected at time intervals, as shown in FIG. 9. The total dyeing time at 85 C. was 20 min.

[0149] Both non-metallised acid (Erionyl Red A-28F (Huntsman)) and 1:2 pre-metallised acid dyes (Supralan Yellow 4GL (Dystar); Lanaset Yellow 2R (Huntsman) and Neutrilan Yellow A-3R (Yorkshire)) were applied to wool, silk and PA fabrics using the dyeing methods of the invention. In addition, both commercial grade as well as crude grade samples of the disperse dye Teratop Yellow HL-G 150% (Huntsman) was applied to wool, PA and wool fibres.

[0150] Both silk and wool were successfully dyed at 85 C. in 20 min using the non-metallised dye Erionyl Red A-28F. colour measurement L*=34.3 a*=63.4 b*=58.1

[0151] In comparison to the conventional method for dyeing wool with such dye types, which is normally carried out at higher temperature (for wool: 98 C.) under acidic conditions for 60-90 min, the novel dyeing method is advantageous insofar as it enables the fibres to be dyed at a lower temperature of 85 C. (for wool) in a short time (ie 20 min) without recourse to pH adjustment, thereby offering savings in time, energy and chemicals.

[0152] Both silk and wool were successfully dyed at 85 C. for 20 min using the 1:2 metal complex dye Supralan Yellow 4GL at 85 C. for 20 min using the novel dyeing method colour measurement L*=83.8 a*=6.9 b*=116.5. Once again, compared to the conventional method for dyeing wool with such dye types, which is normally carried out at higher temperature (for wool: 98 C.) under acidic conditions for 60-90 min, the novel dyeing enables the fibres to be dyed at 85 C. in a short time (ie 20 min) and without using pH adjustment, thereby offering savings in time, energy and chemicals.

[0153] The novel dyeing method also enabled wool and silk to be dyed at 85 C. for 20 min using the 1:2 metal complex dyes Neutrilan Yellow A-3R colour measurement L*=48.7 a*=34.5 b*=8.1 and Lanaset Yellow 2R. Once again, compared to the conventional method for dyeing wool with such dye types, which is normally carried out at higher temperature (for wool) under acidic conditions for 60-90 min, the novel dyeing enables the fibres to be dyed at 85 C. in a short time (ie 20 min), thereby offering savings in time, energy and chemicals.

[0154] Both commercial (i.e. containing dispersants) and crude (i.e. not containing dispersants) samples of the disperse dye Teratop Yellow HL-G 150% were successfully applied to both scoured wool and silk and PA fibres using the novel dyeing method at 85 C. and 20 min.

Example 4Blends of Fibres

[0155] The methods of the invention can also be used to dye a combination of different types of fibre. The following example describes the dyeing of polyester/cotton blends as well as polyester/Nylon blends using disperse dye.

[0156] The general method used throughout this example is shown in FIG. 9. A Roaches Pyrotec S dyeing machine) was used. The appropriate amount of crude grade disperse dye to provide a 2% omf shade was dissolved in 10 cm.sup.3 acetone and the ensuing solution was placed in a 300 cm.sup.3 capacity dye tube, followed by a fabric composite comprising 2.5 g of polyester fabric attached to 2.5 g of scoured, bleached and mercerised woven cotton fabric. The sealed dye tube was heated to 98 C. and then 10 cm.sup.3 of water was injected into the dyeing tube. A further total of 40 cm.sup.3 of water was injected at time intervals, as shown in FIG. 9. The total dyeing time at 85 C. was 20 min.

[0157] 2% omf dyeings of the crude (i.e. not containing dispersants) disperse dyes Teratop Yellow HL-G 150%, Teratop Blue HL-G 150% and Teratop Pink HL-G 150%, were successfully achieved using the novel dyeing method at 98 C. and 20 min. Whilst the polyester component was fully dyed, the cotton fabric was uncoloured. This was anticipated based on the relative hydrophobicity of the cotton and polyester fibres and the corresponding different substantivity for the fibres displayed by the disperse dye.

[0158] Following the method described above, a 2% omf dyeing using the crude grade disperse dye Teratop Yellow HL-G 150% was obtained using a fabric composite comprising 2.5 g of polyester fabric attached to 2.5 g of scoured PA 66 fabric.

[0159] Both the polyester and nylon 66 fabrics were dyed, as shown by FIG. 10, but the polyester was of higher depth of shade, as expected, owing to the greater hydrophobicity of the polyester material and the corresponding greater substantivity displayed by the dye towards the polyester fibre.

Example 5Solvent Mixtures

[0160] The first solvent can comprise a mixture of two or more organic solvents or a mixture of water and an organic solvent.

[0161] The general method used throughout this example is shown in FIG. 9, with the acetone replaced with mixed solvent systems as described below. A Roaches Pyrotec S dyeing machine) was used. Crude grade disperse dye Teratop Yellow HL-G 150%, was dissolved in a mixture of 10 cm.sup.3 acetone and 2 cm.sup.3 of water. The ensuing solution was placed in a 300 cm.sup.3 capacity dye tube, followed by polyester fabric. The sealed dye tube was heated to 98 C. and then 10 cm.sup.3 of water was injected into the dyeing tube. A further total of 40 cm.sup.3 of water was injected at time intervals. The total dyeing time at 98 C. was 20 min.

[0162] The colour strength of the ensuing dyeing was very similar to that obtained when acetone only had been used as the first solvent.

[0163] When the above method was used but crude grade disperse dye Teratop Yellow HL-G 150% was dissolved in a mixture of 4 cm.sup.3 acetone and 6 cm.sup.3 of ethanol, successful dyeing was achieved.

Example 6Other Solvents

[0164] Although acetone is an excellent solvent for crude grade disperse dyes, other, higher boiling solvents were examined. Being higher boiling, these solvents offer a reduced fire risk compared to acetone.

[0165] Different amounts (5, 10 and 20 cm.sup.3) of DMSO were used to dissolve 2% omf commercial Teratop Yellow HL-G and different amounts of water (45, 40 and 30 cm.sup.3) were added portionwise so as to achieve a 1:10 LR overall were used. The colour strength of the dyed polyester is shown in FIG. 11

[0166] From FIG. 11 it is apparent that lower values of colour strength are obtained in comparison to that of PES which had been dyed using acetone, which can be attributed to the lower solubility of the dye in DMSO. However, as FIG. 11 shows, by increasing the amount of DMSO employed, higher colour strength dyeings were achieved. While these dyeings did not exhibit the high colour strengths of the acetone processes, they still offer benefits in terms of lower temperature of process with lower energy use and the ability to dye PES concurrently with non-PES fibres.

[0167] Various other high boiling point solvents were used to dye PES at a 2% omf depth of shade of crude Teratop Yellow HL-G, namely ethylene glycol diacetate (EGD), triethylene glycol monomethyl ether (TGM), dipropylene glycol methyl ether (DME) and 1-methoxy-2-propanol.

[0168] Samples of PES fabric were dyed at 95 C. using the controlled precipitation dyeing method shown in FIG. 3, employing each of the above solvents (10 cm.sup.3) and 4 additions of water (40 cm.sup.3 water in total; 1:10 LR in total), the total dyeing time at 95 C. being 20 mins.

[0169] Colour measurement data (illuminant D.sub.65; specular included; UV excluded; 10 standard observer)

triethylene glycol monomethyl ether (TGM) L*=88.9a*=30.5b*=95.3

ethylene glycol diacetate (EGD) L*=86.1a*=19.1b*=80.1

[0170] Each of the four solvents were able to dissolve the crude disperse dye and can be utilised in the precipitation dyeing method.

Example 7Vat Dyes

[0171] To investigate whether the novel precipitation dyeing method could be used to apply to vat dyes, indigo was selected. Samples of PES fabric were dyed at 95 C. using the controlled precipitation dyeing method shown in FIG. 3, employing acetone as solvent (10 cm.sup.3) and 4 additions of water (40 cm.sup.3 water in total; 1:10 LR in total), the total dyeing time at 95 C. being 20 mins.

[0172] It was found that the vat dye could be applied from acetone using the precipitation dyeing method.

[0173] No reductants or pH adjustments were needed to achieve this result.

[0174] Colour measurement data (illuminant D.sub.65; specular included; UV excluded; 10 standard observer)

[0175] L*=55.9 a*=6.3 b*=10.9

Example 8One Pot Dyeing of Mixtures of Fibres with Mixtures of Classes of Dyes

[0176] The novel precipitation dyeing method may offer the potential for dyeing fibre blends using different classes/types of dye simultaneously, in the same dyebath, in the absence/much reduced amounts of dyebath auxiliaries.

[0177] For this example, samples (2.5 g) of fabric were dyed at different temperatures using the controlled precipitation dyeing method shown in FIG. 3, employing acetone as primary solvent and using additions of water or solutions of inorganic electrolyte or alkali, as well as electrolyte/alkali, the total dyeing time being 20 mins. The amounts are given in the examples below

PES/Cotton Using Reactive Dye and Disperse Dye

[0178] Duractive Black B (C.I. Reactive Black 5) and crude Teratop Yellow HL-G were dissolved in acetone. Separate samples of PES fabric and cotton fabric were dyed together at 95 C. using the controlled precipitation dyeing method shown in FIG. 3, employing 4 additions of either a) water or b) a solution comprising 15 gl.sup.1 Na.sub.2CO.sub.3 and 50 gl.sup.1 NaCl (1:10 LR in total), the total dyeing time being 20 mins.

[0179] It was found that it is possible to dye both the hydrophobic PES and hydrophilic cotton substrates in the same dyebath in 20 minutes at 95 C., using a mixture of non-ionic disperse dye and anionic reactive dye. As expected the colour yield secured using both electrolyte and alkali favoured reactive dye uptake.

[0180] Since it is now known that reactive dye exhaustion on cotton in the absence of added inorganic electrolyte can be increased through the use of low liquor ratio, dyeings were also made using two 10 cm.sup.3 additions (1:6 LR) of a solution comprising 15 gl.sup.1 Na.sub.2CO.sub.3; an improvement in depth of shade of the reactive dye on the cotton component was achieved compared to that obtained at a 1:10 LR.

[0181] To samples of PES fabric and cotton fabric Commercial Novacron Red FN-2BL was applied in conjunction with crude Teratop Yellow HL-G dissolved in acetone. Four 10 cm.sup.3 additions of a solution comprising 15 gl.sup.1 Na.sub.2CO were made (1:10 LR); the total dyeing time was 20 mins at 95 C. It was found that the precipitation method enables PES and cotton substrates to be dyed in the same dyebath in 20 minutes at 95 C., using a mixture of disperse dye and reactive dye.

Colour Measurement

[0182] PES L*=75.8 a*=18.9 b*=116.5

[0183] cotton L*=52.9 a*=4.3 b*=19.8

PES/Cotton Using Direct Dye and Disperse Dye

[0184] C.I. Direct Red 81 and crude Teratop Yellow HL-G were dissolved in acetone. Samples of PES fabric and cotton fabric were dyed at 95 C. using the controlled precipitation dyeing method shown in FIG. 3, employing 4 additions of water or a solution containing 20 gl.sup.1 NaCl (1:10 LR in total), the total dyeing time being 20 mins.

Colour Measurement

[0185] PES L*=73.1 a*=16.1 b*=117.6

[0186] cotton L*=41.1 a*=66.9 b*=19.4

[0187] Dyeings were also made using two 10 cm.sup.3 additions (1:6 LR) of water

[0188] Colour Measurement

[0189] PES L*=78.4 a*=35.8 b*=111.9

[0190] cotton L*=52.3 a*=61.6 b*=11.2

[0191] It was found that both PES and cotton fibres can be dyed simultaneously in the same dyebath in 20 minutes at 95 C., using a mixture of disperse dye and direct dye; as expected the colour yield secured using electrolyte favoured dye uptake, and using a lower liquor ratio (ie 1:6) improved direct dye adsorption in the absence of added inorganic electrolyte.

PES/Wool Using Non-Metallised and Pre-Metallised Acid Dyes in Conjunction with Disperse Dye

[0192] Commercial samples of either a) the non-metallised acid dye Erionyl Red A-28F or b) the 1:2 pre-metallised acid dye Neutrilan Yellow A-3R were dissolved in acetone along with crude (i.e. containing no auxiliaries) Teratop Yellow HL-G. Samples of PES fabric and wool fabric were dyed at 85 C. using the controlled precipitation dyeing method shown in FIG. 3, employing 4 additions of water (1:10 LR in total), the total dyeing time being 20 mins.

[0193] It was found that PES and wool fibres can be dyed simultaneously in the same dyebath in 20 minutes at 85 C., using a mixture of disperse dye and either non-metallised acid or pre-metallised acid dyes in the absence of all dyeing auxiliaries. The wool fabric component was dyed either a red colour or yellow colour depending on the type of acid dyes used, and the polyester fabric component was dyed a yellow colour

PES/Silk Using Non-Metallised and Pre-Metallised Acid Dyes in Conjunction with Disperse Dye

[0194] Commercial samples of either a) the non-metallised acid dye Erionyl Red A-28F or b) the 1:2 pre-metallised acid dye Neutrilan Yellow A-3R were dissolved in acetone along with crude (i.e. containing no auxiliaries) Teratop Yellow HL-G. Samples of PES fabric and silk fabric were dyed at 85 C. using the controlled precipitation dyeing method shown in FIG. 3, employing 4 additions of water (1:10 LR in total), the total dyeing time being 20 mins.

[0195] It was found that PES and wool fibres can be dyed simultaneously in the same dyebath in 20 minutes at 85 C., using a mixture of disperse dye and either non-metallised acid or pre-metallised acid dyes in the absence of all dyeing auxiliaries. The silk fabric component was dyed either a red colour or yellow colour depending on the type of acid dyes used, and the polyester fabric component was dyed a yellow colour

PES/Cotton/Wool Using Non-Metallised Acid and Reactive Dyes in Conjunction with Disperse Dye

[0196] Commercial samples of the non-metallised acid dye Erionyl Red A-2BF and Duractive Black B were dissolved in acetone along with with crude Teratop Yellow HL-G. Samples of PES fabric, wool fabric and cotton fabric were dyed at 85 C. using the controlled precipitation dyeing method shown in FIG. 3, employing 4 additions of water (1:10 LR in total), the total dyeing time being 20 mins.

[0197] The cotton fabric component was dyed a blue colour, the wool fabric was dyed a red colour and the polyester fabric component was dyed a yellow colour.

[0198] The results showed that PES, wool and cotton fibres can be dyed different colours simultaneously in the same dyebath in 20 minutes at 85 C., using a mixture of disperse dye, reactive dye and non-metallised acid dye in the absence of all dyeing auxiliaries.

Example 8One Pot Dyeing of a Solid Object

[0199] This example describes the results obtained from dyeing 3D printed nylon 12 (PA12) with a disperse dye (Dianix Blue-ACE) at the boil (98 C.) under atmospheric pressure, using two different solvent systems. The dyed samples obtained were compared in terms of depth of shade and the process conditions employed (i.e. temperature, solvent system employed).

[0200] The substrate dyed were white solid, 3D printed nylon 12 parts.

[0201] The dye used in this trial was of commercial grade and was used as supplied without purification; Dianix Blue ACE manufactured by Dystar.

[0202] Photographs of all samples were recorded in a light cabinet under D.sub.65 illuminant, using a Samsung Galaxy S6+ mobile phone camera.

[0203] All dyeing was carried-out by placing the dye, substrate and solvent in a container placed on a hot plate and heated to the required processing temperature. The temperature of the dyebath was measured using a mercury-in-glass thermometer.

Solvent System 1 (Water)

[0204] A 2% omf (Dianix Blue-ACE) dyeing was produced following the procedure shown in FIG. 12A, employing a 10:1 LR. At the end of dyeing, the sample was rinsed thoroughly under running tap water and dried in the open air. A photograph of the dyed sample is shown in FIG. 12B

Solvent System 2 (Water:Glycerol; 80:20)

[0205] A 2% omf (Dianix Blue-ACE) was produced following the procedure shown in FIG. 12C, employing a 10:1 LR (liquor comprising of water:glycerol; 80:20) At the end of dyeing, the samples was rinsed thoroughly under running tap water and dried in the open air. A photograph of the dyed sample is shown in FIG. 12D

[0206] Upon visual inspection of the dyed samples it was apparent that, the sample obtained using the glycerol: water solvent system had the highest depth of shade (compare FIG. 12B and FIG. 12D).