DESC:FIELD OF INVENTION
The present invention relates to synthesis of disperse reactive azo dyes and dyeing of polyamide/nylon, silk, wool, Cotton and polyester and blends of these fibers. A method for dyeing polyamide/nylon, silk, wool, Cotton and polyester and blends of these fibers with fiber reactive disperse azo dyestuffs in a supercritical fluid such as CO2. Polyamide/nylon, wool, silk and polyester fibers dyed with this method exhibit better fastness property in comparison to those dyed using traditional dyeing methods.

BACKGROUND OF INVENTION
Traditionally, polyamide/wool/silk fabrics dyed with water soluble Acid dyes using conventional aqueous dyeing and printing technology.
Increasing awareness on environmental issues and excessive water consumption in conventional dyeing and printing technology, need for the development of alternate dyeing and printing technologies are of very high priorities. In this regards various technological developments are commercialized in the recent past and still development is in progress to make these technologies mature enough to compete with the age old conventional water dyeing and printing technology.
Digital Printing, Dyeing with super critical fluid (Carbon Dioxide), Plasma Dyeing, Foam Dyeing and Transfer Printing are some examples of waterless dyeing and printing technologies.
Martijn van der Kraan et al (Process and Equipment Development for Textile Dyeing in Supercritical Carbon Dioxide) in 2005 discusses the usage of Disperse dyes containing a reactive vinylsulphone or a dichlorotriazine group, are suitable for dyeing textiles containing polyester, nylon, silk, wool or blends of these fibers in supercritical carbon dioxide.
Shen Kung Liao et al. (Dyeing nylon-6,6 with some hydrophobic reactive dyes by supercritical processing) in Journal of Polymer Research 2004, Volume 11, Issue 4, pp 285-291 describes that Nylon-6,6 fibers, spun from the polyamide (polyhexamethylene diamine adipate) are dyed with hydrophobic reactive dyes using supercritical carbon dioxide as the solvent system to provide fabrics with moderate to good dye uptake.
S K Liao, Y C Ho and P S Chang et al in Dyeing of nylon 66 with a disperse-reactive dye using supercritical carbon dioxide as the transport medium in Coloration Technology Volume 11, Issue 12, pages 403-407 December 2000 describe Nylon 66 fabric dyed with a disperse-reactive yellow dyestuff using a supercritical carbon dioxide dyeing process indicating that the fabric immersed in supercritical carbon dioxide does not undergo any fiber damage.
Garay, I et al in Polyamide and polypropylene textile dyeing using supercritical carbon dioxide (sc-CO2) describes the development of an alternative textile dyeing method for dyeing of two polyamides (PA-6, PA-6.6) and polypropylene with an acid dye using supercritical carbon dioxide (sc-CO2).
WO2007066415 describes dyeing of a fibrous material of a meta-type wholly aromatic polyamide in a dyeing system comprising a subcritical to supercritical carbon dioxide and a dye in the presence of a polar solvent (e.g., water, methanol, acetone, propanol, or ethylene glycol) so as to give fibrous material which is evenly dyed in a high color density from the surface to the inner part of the fibers.
JP2001348785 describes method for treating a wholly aromatic polyamide fiber which is characterized by comprising incorporating fillers and water in the wholly aromatic polyamide fiber with its moisture content maintained continually at >=15 wt.% after spun followed by treatment with a supercritical fluid.

Dierk Knittel and Eckhard Schollmeyer in article entitled “Environmentally friendly dyeing of synthetic fibers and textile accessories” published in International Journal of Clothing Science and Technology Volume 7 Issue 1 discusses a survey about a new process for dyeing synthetic fibres and fabrics such as polyethylene terephthalate and polyamides. It further indicates that the use of disperse dyes in supercritical carbon dioxide as a dyeing medium completely avoids water pollution and the need for drying.

An article entitled “Damage to Natural and Synthetic Fibers Treated in Supercritical Carbon Dioxide at 300 bar and Temperatures up to 160°C” in Textile Research Journal November 2002 vol. 72 no. 11 1023-1032 discusses fiber damage in cotton, viscose, polyester, poly amide 6.6, silk, and wool in supercritical carbon dioxide at 100, 120, 140, and 160°C for 1 and 4 hours at a pressure of 300 bar. It further indicates that shrinkage occurs only in polyamide 6.6 and polyester, and is comparable to water dyeing. It further discloses that except for polyamide 6.6, where treatment conditions are limited to 120°C at 300 bar for 1 hour, supercritical carbon dioxide is a suitable solvent for dyeing or other treatments, even for the most sensitive textiles up to 140°C.

Thus the dyeing of substrate materials in liquid or supercritical carbon dioxide is well-known in the art. It is also known to employ reactive dyeing substances in supercritical dyeing methods that are capable of reacting with the substrate under the formation of a chemical bond. These reactive substances are usually derivatives of CO2-soluble disperse dyestuffs (chromophores) that contain a reactive group that is capable of reacting with specific residues in the substrate.

Unfortunately, supercritical dyeing methods employing the aforementioned reactive dyestuffs have been found to produce disappointing colour yields and to suffer from poor fixation of the dye to the substrate. Several attempts have been made to modify the dyeing methodology in order to obtain more satisfactory results with these reactive dyestuffs.

Moreover, in all the cases there is a need for pretreatment of fabric to obtain reasonably better results compare to fabric without pretreatment.

Even with this pretreatment with polar solvent dyeing yield on fabric is not satisfactory especially with cotton.

OBJECT OF INVENTION
It is an object of the invention to provide a method for dyeing polyamide/nylon, silk, wool, polyester and blends of these fibers with fiber reactive disperse dyestuffs in a supercritical carbon dioxide.

It is another object of the invention to provide a method for dyeing polyamide/nylon, silk, wool, polyester and blends of these fibers with better fastness properties.

It is another object of the invention to provide an economically feasible method for dyeing polyamide/nylon and polyester fibers with fiber reactive disperse dyestuffs.

It is another object of the invention to provide an environmental friendly method for dyeing polyamide/nylon and polyester fibers with fiber reactive disperse dyestuffs.

SUMMARY OF INVENTION
A process for Dyeing of fabric selected from polyamide/nylon, silk, wool, polyester or blends of these fibers with fiber-reactive dyes of formula 1,

wherein,
X, Y and Z are, independently, hydrogen, halogen, cyano, nitro or SO2F;
wherein at least one of X, Y and Z is SO2F;
R1 is hydrogen, methyl, hydroxyl or NHR5;
R2 is hydrogen, chloro or methoxy;
R3 and R4 are same or different hydrogen, (C1-C4) alkyl, -CH2CH2OR6, -CH2(CH2)mCOOR6, -CH2CH=CH2;
R5 is –COCH3, -COC2H5, -SO2CH3 or SO2C2H5;
R6 is –H, –COCH3, -COC2H5, -O(C1-C4)alkyl; -CH2CN, -C2H4CN
m is independently 0,1 or 2;
said dyeing process comprising the steps of:
i. Placing the dyestuff of formula-1 in a dyeing pot along with the fabric;
ii. Closing the dyeing pot tightly;
iii. Purging desired quantity of supercritical fluid to the tightly closed dyeing pot of step ii;
iv. Subjecting it to dyeing cycle at 100-130°C and 200-300 bar pressure for at least 90 minutes.

DESCRIPTION OF INVENTION
The present inventors have surprisingly found that when the disperse dyes of formula (I) are applied onto a polyamide/nylon fiber through a process employing the use of supercritical carbon dioxide, the dyed polyamide/nylon fibers exhibit better fastness properties as against those which have been dyed using conventional techniques.

The three essential components in the supercritical CO2 dyeing process are - Carbon Dioxide, dyestuff and fabric. Under the specified dyeing condition the dyestuff gets dissolved in the supercritical carbon dioxide, transferred to polyester fabric and diffused into the fiber to get uniform dyeing.

In general this principle also applied for dyeing of polyamide fabric using supercritical carbon dioxide but Dyes of formula-I having minimum one –SO2F group actually reacts with the polyamide fabric to form covalent bond under this dyeing condition which impart better fastness properties to the dyed polyamide fabric. In fact under conventional dyeing condition this reactive group hydrolyzed and convert in to –SO3H, to become normal acid dyes and get exhausted on polyamide fabric,

The dyestuff to be dissolved in the supercritical fluid comprises disperse dyes of formula (1):

where in,
X, Y and Z are, independently, hydrogen, halogen, cyano, nitro or SO2F;
Where in at least one of X, Y and Z is SO2F;
R1 is hydrogen, methyl, hydroxyl or NHR5;
R2 is hydrogen, chloro or methoxy;
R3 and R4 are same or different hydrogen, (C1-C4) alkyl, -CH2CH2OR6, -CH2(CH2)mCOOR6, -CH2CH=CH2;
R5 is –COCH3, -COC2H5, -SO2CH3 or SO2C2H5;
R6 is –H, –COCH3, -COC2H5, -O(C1-C4)alkyl; -CH2CN, -C2H4CN;
m is independently 0,1 or 2.

The disperse dyes used in the present invention essentially comprises substituent’s with at least one -SO2F group. The -SO2F substituent forms covalent bond with the amido substituent on the polyamide fiber due to which the dyed material exhibits good fastness properties. Further usage of the supercritical fluid technique for dyeing these disperse dyes onto polyamide, wool, silk and polyester fibers leads to dyed material with much better fastness properties as also provides an energy efficient and economical option as also helps in significant reduction in environmental pollution.
The dyeing process of the present invention comprises the steps of:
i. Placing the dyestuff of formula-1 in a dyeing pot along with the fabric;
ii. Closing the dyeing pot tightly;
iii. Purging desired quantity of supercritical fluid to the tightly closed dyeing pot of step ii;
iv. Subjecting it to dyeing cycle at 100-130°C and 200-300 bar pressure for at least 90 minutes.

In one embodiment, the process step comprises of exactly weigh quantity of Dye of formula-1 and fabric are placed in dyeing pot and subsequently closed tightly. Desire quantity of Liquid CO2 is purge to this tightly closed dyeing pot which is than subjected to dyeing cycle at 120°C and 250 bar pressure for 90 minutes.

In one embodiment of the present invention, the method eliminates usage of co-solvent. In all the previous references for dyeing with supercritical fluid involved usage of co-solvent to improve dyeability particularly for the fiber reactive dyestuff to form covalent bond.

Farbwerke Hoechst have developed an identification scheme very much similar to the one described by Bode. The general conclusion drawn from this information is that although there is no specific test for reactive dyes, it is possible to distinguish between them and all other class of dyes by treating the dyeing with certain solvents. Reactive dyes by virtue of the covalent bond between the dye and the cellulose molecule are not removed from the fiber during such treatments. Similarly polyamide dyed with SCF dyeing method using dyes of formula-1 having minimum one –SO2F reactive group were subjected to following solvent treatment,
i) Washing with Acetone
ii) Mixture of glacial acetic acid and ethanol (1:1 v/v)
iii) DMF

All dyes taken for study were showing significant stability even such harsh condition and there was no stripping of dyes from dyed polyamide. This confirms existence of covalent bond between dye molecule and polyamide.

Additionally it was also confirmed by FTIR spectroscopy of Dye powder, Polyamide fabric and dyed polyamide fabric which indicate absence of fluoro and presence of sulphonamide bonding in the dyed material.

Further to this it was confirmed by the fact that when polyester and polyamide both dyed with same dyes from formula-1 it gives different hues on both fabrics. In general on polyamide fabric it gives hypsochromic shift of minimum 20-40 nm compare to polyester fabric. This further confirmed that dye actually react with polyamide fabric and formed covalent bond which ultimately resulted in change in hue on polyamide. This is further confirmed by reacting dye molecule with primary alkyl amine and secondary amine and in both the cases it gives similar hue with shift of 20-40 nm in ?max of reflectance on polyester. This further provides support to the explanation of difference in hue with same dye on polyester and polyamide. Moreover these dyes of formula-2A gives very pale staining on polyamide which confirms that in formula-1 SO2F react with polyamide and formed covalent bond.

Advantages of supercritical dyeing process over conventional dyeing process
The environmentally friendly supercritical fluid dyeing does not require any water dispersing agents and surfactants in the dyeing process. It also saves energy as it does not require any drying stage after dyeing.
Further the process of dyeing and the act of removing the excess dye can be carried out in the same reactor.
Since supercritical CO2 acts as dye solvent, its high diffusion rates and low mass transfer resistance observed in supercritical CO2 compared to water, facilitate the dye penetration into the fibers, which also allows a reduction in the time taken for dyeing.
Further since water is not used there is no likelihood of the dye getting hydrolyzed, therefore essentially all dye molecules are available for reaction with the fiber.
In supercritical dyeing, the dye concentration required for a specific shade is also smaller. Unlike water dyeing, the dye can be easily removed from the supercritical CO2 by simply lowering the pressure. Carbon dioxide and dye can be then reused, making the process economically feasible and environmentally attractive.

The following examples serve to illustrate the efficient fastness properties exhibited by the dyes of formula (I) on polyamide /polyester and blend of those fabrics on dyeing through SCF dyeing technique and are by no means restricted to such specific examples only.

Examples:
The present invention is concretely explained as follows, but the present invention is not limited in these examples.

Example-1:
Structural formula (2)

Formula (2)
Example 1 of structural formula (2) is synthesized by following method:
40% nitrosyl sulfuric acid 3 ml is added to the mixture of 2:5-dichlorofluorosulfonyl aniline 2.0 g, acetic acid and propionic acid (86:14, 25ml) at 0-5 ºC and stirred for 2 hrs below 5ºC. Coupler, N:N’-Diethylaniline 1.22 g is dissolved in dilute HCl 100 ml and the synthesized diazotized solution is added into this coupler solution at 0-5 ºC. The reaction mass is stirred for 1hr below 5ºC and filtered the crystal solid and washed with water.
The 7.0g of 50% wet cake is obtained. The yield is 80%. The ?max in acetone of example 1 dyestuff is 530 nm.

Example-2:
Structural formula (3)

Formula (3)
Example 1 of structural formula (3) is synthesized by following method:
40% nitrosyl sulfuric acid 3 ml is added to the mixture of 2:5-dichlorofluorosulfonyl aniline 2.0 g, acetic acid and propionic acid (86:14, 25ml) at 0-5 ºC and stirred for 2 hrs below 5ºC. Coupler, 3-N:N’-Diacetoxyethyl acetanilide 2.64 g is dissolved in dilute HCl 100 ml and the synthesized diazotized solution is added into this coupler solution at 0-5 ºC. The reaction mass is stirred for 1hr below 5ºC and filtered the crystal solid and washed with water.
The 8.5g of 50% wet cake is obtained. The yield is 90%. The ?max in acetone of example 2 dyestuff is 558 nm.

Example-3:
Structural formula (4)

Formula (4)
Example 3 of structural formula (4) is synthesized by following method:
40% nitrosyl sulfuric acid 3 ml is added to the mixture of 2:5-dichlorofluorosulfonyl aniline 2.0 g, acetic acid and propionic acid (86:14, 25ml) at 0-5 ºC and stirred for 2 hrs below 5ºC. Coupler, 3-N:N’-Diethyl acetanilide 1.69 g is dissolved in dilute HCl 100 ml and the synthesized diazotized solution is added into this coupler solution at 0-5 ºC. The reaction mass is stirred for 1hr below 5ºC and filtered the crystal solid and washed with water.
The 6.8g of 50% wet cake is obtained. The yield is 90%. The ?max in acetone of example 3 dyestuff is 548 nm.

Example-4:
Structural formula (5)

Formula (5)
Example 4 of structural formula (5) is synthesized by following method:
40% nitrosyl sulfuric acid 3 ml is added to the mixture of 2:5-dichlorofluorosulfonyl aniline 2.0 g, acetic acid and propionic acid (86:14, 25ml) at 0-5 ºC and stirred for 2 hrs below 5ºC. Coupler, 3-N:N’-Diethyl acetanilide 1.69 g is dissolved in dilute HCl 100 ml and the synthesized diazotized solution is added into this coupler solution at 0-5 ºC. The reaction mass is stirred for 1hr below 5ºC and filtered the crystal solid and washed with water.
The 6.8g of 50% wet cake is obtained. The yield is 90%. The ?max in acetone of example 4 dyestuff is 542 nm.

Example-5:
Structural formula (6)

Formula (6)
Example-5 of structural formula (6) is synthesized by following method:
40% nitrosyl sulfuric acid 3 ml is added to the mixture of 2:5-dichlorofluorosulfonyl aniline 2.0 g, acetic acid and propionic acid (86:14, 25ml) at 0-5 ºC and stirred for 2 hrs below 5ºC. Coupler, 3-N:N’-Diethyl-4-methoxy- acetanilide 1.93 g is dissolved in dilute HCl 100 ml and the synthesized diazotized solution is added into this coupler solution at 0-5 ºC. The reaction mass is stirred for 1hr below 5ºC and filtered the crystal solid and washed with water.
The 6.8g of 50% wet cake is obtained. The yield is 85%. The ?max in acetone of example 5 dyestuff is 581 nm.
Example-6:
Structural formula (7)

Formula (7)
Example-5 of structural formula (7) is synthesized by following method:
4-amino benzenesulfonyl fluoride 2.0 g, dissolved in 10 ml 30% HCl and cool to 0-5 ºC with addition to ice and stirred well. Slowly add 0.8 gm sodium nitrite as 20% solution below 5ºC and stirred for 2 hr maintaining temperature below 5ºC. Coupler, N:N’-Diethyl aniline 1.7 g is dissolved in dilute HCl 100 ml and the synthesized diazotized solution is added into this coupler solution at 0-5 ºC. The reaction mass is stirred for 1hr below 5ºC and filtered the crystal solid and washed with water.
The 6.8g of 50% wet cake is obtained. The yield is 90%. The ?max in acetone of example 5 dyestuff is 528 nm.

Above wet press cake of formula (2) is further used in four different dyeing methods,

1. Conventional Exhaust Dyeing of Polyester
2.0 g of the obtained wet press cake is milled with 2.0g of naphthalenesulfonic acid-formaldehyde condensate and 50g of water and 500 g of glass beads (average side is 0.8mm of diameter.) for 24 hr and after milling, the mass is filtered to separate glass beads.
The 20g of the obtained finished liquid is added in the 100 ml of water and kept the pH 4 with acetic acid, and 10g piece of polyester is added into the dye bath for exhaust dyeing.
The dyeing bath is heated to 135 ºC and kept for 40min. After proper rinsing, washing and drying, the dyed material is evaluated for reflectance, washing fastness, lightfastness and sublimation fastness.
2. Dyeing of Polyester with Super Critical Fluid (CO2)
Laboratory Dyeing of polyester fabrics with super critical fluid (CO2) comprises the steps of placing dyes up to 2% of the weight of polyester fabric and 10 gms of polyester fabric in dyeing pot depending upon the shade requirement. Close the dyeing pot tightly, Purging desired quantity of Liquid CO2 to this tightly closed dyeing pot; subjecting it to dyeing cycle at 120°C and 250 bar pressure for 90 minutes. After proper rinsing, washing and drying, the dyed material is evaluated for reflectance, washing fastness, lightfastness and sublimation fastness.
3. Conventional dyeing of polyamide (Data required for comparison)
The 0.2g of dye powder added in the 250 ml of water and kept the pH 4 and 10g piece of polyamide is added into the dye bath for exhaust dyeing. The dyeing bath is heated to 98 ºC and kept for 60 min. After proper rinsing, washing and drying, the dyed material is evaluated for reflectance, washing fastness, lightfastness and sublimation fastness.
4. Dyeing with Super Critical Fluid (CO2) of Polyamide
Laboratory Dyeing of polyester fabrics with super critical fluid (CO2) comprises the steps of placing dyes of formula-I (up to 2% of the weight of polyester fabric) and 10 gms of polyamide fabric in dyeing pot. Close the dyeing pot tightly, Purging desired quantity of Liquid CO2 to this tightly closed dyeing pot; subjecting it to dyeing cycle at 120°C and 250 bar pressure for 90 minutes. After proper rinsing, washing and drying, the dyed material is evaluated for reflectance, washing fastness, lightfastness and sublimation fastness.All above differently dyed fabrics were evaluated for Reflectance Spectra for colour measurements and Fastness properties using following test methods, Washing Fastness as per Test Method AATCC 61 2A, Light Fastness as per Test Method ISO 105 B02 and Sublimation Test at 180 deg for 30 sec and at 210 deg for 30 sec.

DYE ?max nm Washing Fastness Light Fastness Sublimation Fastness
AC CO PA PES
Formula-1 530 3 3-4 2-3 4 2 3-4
Formula-2 558 4-5 4 3-4 4-5 3-4 4-5
Formula-3 548 3-4 3-4 3 4-5 3 4
Formula-4 542 4 3-4 3-4 5 3-4 4-5
Formula-5 581 4 4 3-4 5 3-4 4-5

These dyes were also applied to polyamide fabric using conventional dyeing method but it does not give proper dyeing which provide confirmation on formation of covalent bond with polyamide when dyeing using SCF carbon dioxide.

To further confirm fixation on polyamide, dyed polyamide fabric using carbon dioxide is subjected to after treatment with Acetone, Ethanol: Acetic acid (1:1 mixture) and even with DMF and in all very little dye get removed in washing.
DYE Dyeing without after treatment After treatment with
Acetone at RT DMF at RT LEO+AA (1:1) RT
% Strength % Strength % Strength % Strength
FORMULA-1 100 70.00 71.00 60.00
FORMULA-2 100 78.00 74.00 70.00
FORMULA-3 100 80.00 79.00 72.00
FORMULA-4 100 81.00 78.00 69.00
FORMULA-5 100 79.00 73.00 77.00
POLYESTER DYEING OF FORLUMA-1 IN SCF 100 99 100 98

For further confirmation FTIR spectrum of Dye powder (Figure 1) and SCF dyed polyamide fabric (Figure 2) is performed which clearly shows presence of strong peak representing sulphonamide stretching at 3290 in FTIR of SCF dyed polyamide fabric and absence of strong stretching at 1321 and 1394 representing –SO2F in dyed polyamide which is present in dye powder FTIR.

It was further confirmed by reacting above dye molecule of formula 2 with n-butylamine in presence of anhydrous potassium carbonate to get Butylsulphonamide derivative having following formula,
Formula-2A
When polyamide fabric is dyed with this Dye-2A using SCF carbon dioxide it gives very pale staining on polyamide where as it gives uniform dyeing with reflectance ?max of 500 nm compare to 520 nm reflectance of dye of Formula-2.

Similarly, different derivatives of formula-1 were prepared and further studied for different fastness properties on polyester and polyamide using conventional dyeing technology as well as SCF dyeing technology.
,CLAIMS:1. A process for Dyeing of fabric selected from polyamide/nylon, silk, wool, polyester or blends of these fibers with fiber-reactive dyes of formula 1,
wherein,
X, Y and Z are, independently, hydrogen, halogen, cyano, nitro or SO2F;
wherein at least one of X, Y and Z is SO2F;
R1 is hydrogen, methyl, hydroxyl or NHR5;
R2 is hydrogen, chloro or methoxy;
R3 and R4 are same or different hydrogen, (C1-C4) alkyl, -CH2CH2OR6, -CH2(CH2)mCOOR6, -CH2CH=CH2;
R5 is –COCH3, -COC2H5, -SO2CH3 or SO2C2H5;
R6 is –H, –COCH3, -COC2H5, -O(C1-C4)alkyl; -CH2CN, -C2H4CN;
m is independently 0,1 or 2;
said dyeing process comprising the steps of:
i. Placing the dyestuff of formula-1 in a dyeing pot along with the fabric;
ii. Closing the dyeing pot tightly;
iii. Purging desired quantity of supercritical fluid to the tightly closed dyeing pot of step ii;
iv. Subjecting it to dyeing cycle at a temperature range of 100-130°C and at pressure of 200-300 bar pressure for atleast 90 minutes.

2. A process as claimed in claim 1, wherein dyeing of polyester fiber is carried out at 120°C.
3. A process as claimed in claim 1, wherein dyeing of polyamide fiber is carried out at 100°C and 120°C.

4. A process as claimed in claim 1, wherein dyeing is carried out at a pressure of 250 bar.

5. A process as claimed in claim 1, wherein the supercritical fluid is liquid Carbon dioxide.

6. A process as claimed in claim 1 for dyeing fabric with one or more fiber-reactive dyestuffs of formula 1 wherein the process does not involve the usage of water or any other solvent.