Claims:We claim:

1. A single bath dyeing method for a material of polyester-cotton blends;
the method comprising:
a) a pre-treatment comprising of scouring and cationization of the material in a single bath by suspending the material in water in 1:5 to 8 (wt./vol.) ratio followed by adding 10 to 60 gm/liter of cationizing agent and about 1/4th on the weight of cationizing agent of alkali to adjust the bath pH in the range of 10 to 14 to obtain a cationized material;
b) subjecting the cationized material obtained in step (a) to a hot wash to obtain a washed cationized material;
c) subjecting the washed cationized material obtained in step (b) to neutralization to obtain a neutralized cationized material;
d) subjecting the neutralized cationized material obtained in step (c) to a dyeing in a single bath comprising reactive dyes and disperse dyes in the presence of auxiliaries followed by adding alkali to the dye bath to dye a polyester fiber component and a cotton fiber component of the cationized material to obtain a dyed material;
e) subjecting the dyed material obtained in step (d) to a wash with water to obtain a washed dyed material;
f) subjecting the washed dyed material obtained in step (e) to a neutralization to obtain a neutralized dyed material;
g) subjecting the neutralized dyed material obtained in step (f) to a treatment with wash off agent to obtain a treated dyed material;
h) subjecting the treated dyed material obtained in step (g) to an acid reduction clearing to obtain a treated material;
i) subjecting the treated dyed material obtained in step (h) to a hot wash to obtain a washed dyed material; and
j) subjecting the washed dyed material obtained in step (i) to a wash with water to obtain a dyed material to have good color fastness to wash and to both wet rubbing and dry rubbing properties without sacrificing the shade of the dyed color;
said method reduces water consumption, effluent generation, steps of dyeing, power consumption, energy consumption, cost of dyeing, waste disposal and pollution.
2. The method as claimed in claim 1, wherein the pre-treatment step (a) further comprises bleaching along with scouring and cationization of the material.

3. The method as claimed in claim 1, wherein the step (b) of hot wash comprises loading the cationized material obtained in step (a) and water in the bath, heating the bath in the range of 75°C to 85°C, running the material in the bath for at least 8 to 15 minutes of residence time and draining the bath to obtain a washed cationized material.

4. The method as claimed in claim 1, wherein the step (c) of neutralization comprises loading the washed cationized material obtained in step (b) and water in the bath, adding acid to the bath to adjust the pH in the range of 4 to 6, adding a core neutralizing agent to the bath, running the bath for at least 8 to 15 minutes of residence time while maintaining the pH in the range of 4 to 6 and draining the bath to obtain a neutralized cationized material.

5. The method as claimed in claim 1, wherein the step (d) comprises loading the neutralized cationized material obtained in step (b) and water in the bath, adding auxiliaries in the dye bath, maintaining the pH of the bath in the range of 4 to 6, heating the bath to 60°C, adding both reactive dyes and disperse dyes in the bath, raising the temperature of the dye bath to 90° C followed by heating to 135°C, running the material in the bath for at least 25 to 50 minutes of residence time to dye polyester fiber component of the material, cooling the dye bath to 60°C followed by adding alkali to it to adjust the pH in the range of 9.5 to 11.5, running the material in the bath for at least 25 to 60 minutes to dye cotton fiber component of the material and draining the bath to obtain a dyed material.

6. The method as claimed in claim 5, wherein the step (d) comprises loading the neutralized cationized material obtained in step (c) and water in the bath, adding auxiliaries in the bath, checking and maintaining the pH of the bath in the range of 4.5 to 5.5, heating the bath to 60°C, adding both reactive dyes and disperse dyes in the bath, raising the temperature of the dye bath to 90° C at the rate of 3°C /minute followed by raising the temperature from 90°C to 110°C at the rate of 2.5°C/minute further raising the temperature of the bath from 110°C to 130°C at the rate of 1.5°C /minute followed by running the material in the bath for at least 25 to 45 minutes to dye polyester fiber component of the material, cooling the dye bath from 130°C to 110°C at the rate of 1.5°C/minute followed by cooling the bath from 110°C to 90°C at the rate of 2.5°C/minute further cooling from 90°C to 60°C at the rate of 3°C/minute followed by adding weak alkali and subsequently strong alkali to it to adjust the pH in the range of 9.5 to 10.5, running the material in the bath for at least 25 to 50 minutes to dye cotton fiber component of the material and draining the bath to obtain the dyed material.

7. The method as claimed in claim 1, wherein the step (e) of wash with water comprising loading the dyed material obtained in step (d) and water in the bath, running the material in the bath for at least 8 to 15 minutes of residence time at the temperature in the range of 25°C to 30°C and draining the bath to obtain a washed dyed material.

8. The method as claimed in claim 1, wherein the step (f) of neutralization comprises loading the washed dyed material obtained in step (e) and water in the bath followed by addition of acid to it to adjust the pH of the bath in the range of 4 to 6, adding a core neutralizing agent followed by running the bath for 8 to 15 minutes while maintaining the pH between 4 to 6 and draining the bath to obtain a neutralized dyed material

9. The method as claimed in claim 1, wherein the step (g) of treatment with wash off agent comprises loading the neutralized dyed material obtained in step (f) with water in the bath followed by adding a wash off agent in the bath, raising the temperature of the bath in the range of 80°C to 95°C, running the material in the bath for at least 10 to 20 minutes of residence time at the maintained temperature and draining the bath to obtain a treated dyed material.

10. The method as claimed in claim 1, wherein the step (h) of treatment of acid reduction comprises loading the treated dyed material obtained in step (g) with and water in the bath, adding acid to it to adjust the pH in the range of 4 to 6.5 followed by adding a reduction clearing agent to the bath, heating the bath to 80°C, running the dyed material in the bath for 10 to 20 minutes at maintained temperature and draining the bath to obtain a treated dyed material.
11. The method as claimed in claim 1, wherein the step (i) of treatment of hot wash comprises loading the treated dyed material obtained in step (h) with and water in the bath, heating the bath to raise a temprature in the range of 75°C to 90°C followed by running the material in the bath for at least 8 to 15 minutes at maintained temperature and draining the bath to obtain a washed dyed material.

12. The method as claimed in claim 1, wherein the step (j) of wash with water comprises loading the washed dyed material obtained in step (i) with and water in the bath, running the material in water at temperature in the range of 25°C to 30°C for at least 8 to 15 minutes of residence time and draining the bath to obatin a dyed material.

13. The method as claimed in any of the preceding claims 1 to 12, wherein the method reduces
• number of steps to 10,
• 25 to 35 % of fresh water consumption,
• 25 to 35 % of effluent generated and drained,
• 8 to 25 % of the total time consumption,
• 5 to 15 % of cost of dyeing; and
• eliminates the use of electrolyte/salt;

Dated this 31st day of October 2019

(Dr. Shilpa Gharve)
Agent of the Applicant
, Description:FIELD OF INVENTION:
The present invention relates in general to a method of dyeing for polyester-cotton blends.
In particular, the present invention relates to a single bath dyeing method for polyester-cotton blends, particularly the blends are dyed with disperse dyes and reactive dyes in a single bath in the absence of electrolyte/salt at the same time achieving good fastness properties without compromising with the desired color shade.
The present invention has several advantages including but not limited to reduced water consumption, effluent generation, waste disposal, time consumption, energy consumption, etc. thereby making the current method cost-effective and eco-friendly.

BACKGROUND OF THE INVENTION:
A wide variety of natural and man-made fabrics are available today. But all fabrics are not perfect and have some good, fair or poor characteristics. To make perfect fabrics, the industry experts have produced blended fabrics by spinning an intimate mixture of two or more fibres together in varying proportions. The blending of cellulosic fibres with man-made fibres to produce fabrics with improved characteristics has long been accepted throughout the world.
Blends of cotton and polyester fibres are important textiles used in the manufacture of clothing and other textile products. However, the dyes and dyeing conditions used to dye cotton and polyester fibres are different from each other and thus it is necessary to dye blends of cotton and polyester fibres in two different dye baths.
Cotton fibres and the reactive dyes both are hydrophilic in nature. Therefore, the reactive dyes have a high degree of affinity for cellulosic cotton fibres and form a covalent chemical bond with the hydroxyl groups of cotton and exhibit excellent fastness properties.
The reactive dyes used to dye cotton fibres include but not limited to vinyl sulfone, dichloroquinoxalone, halotriazine and halopyrimidine types which are well known in the art. These reactive dyes are stable under alkaline pH conditions. Hence, the dyeing of cotton fibres with reactive dyes is generally carried out under alkaline conditions at a temperature in the range of 40°C to 110°C in the presence of an electrolyte. The electrolyte promotes exhaustion of the dye from the dye bath to the cotton fibres. Further, these reactive dyes may not be thermally stable.
Unlike cotton fibers, the polyester fibers are hydrophobic and thus, they are generally dyed with hydrophobic disperse dyes. Since, the disperse dyes are sparingly soluble in water, they usually disperse in water with the aid of a dispersing agent like a surfactant in combination with other suitable auxiliaries. Generally, disperse dyes diffuse into the fiber under the influence of heat and dyeing auxiliaries to color the polyester fiber. The disperse dyes are generally not stable at higher pH but may be stable at higher temperature. Further, dispersion of the disperse dyes may be sensitive to electrolytes which may tend to cause dispersion instability. Thus, dyeing of the polyester with disperse dyes is normally carried out at pH 5-7 at a temperature in the range of 120°C to 140°C in the presence of a surfactant in combination with other auxiliaries but in the absence of electrolyte.
The polyester-cotton blends are generally dyed by three well-known exhaust dyeing procedures:
a) a conventional two bath dyeing:
In the conventional two bath dyeing, the polyester-cotton blend is first subjected to dyeing with disperse dyes in a dye bath at pH in the range of 5 to 7 at temperature in the range of 120°C to 140°C to dye the polyester fiber component of the blend. The blend is further subjected to dyeing with reactive dyes in the presence of an electrolyte and an alkali in the second dye bath at temperature in the range of 50°C to 110°C to dye the cotton fiber component of the blend;
b) a reverse two bath dyeing:
In this method, first dyeing of the cotton fiber component of the blend with the reactive dyes is followed by second dyeing of the polyester fiber component with the disperse dyes in the separate dye bath. Thus, it is reverse of the conventional dyeing method; and
c) one bath, multi-step dyeing:
In the one bath multi-step dyeing method, a single dye bath is prepared using reactive dyes and the cotton fiber component of the blend is dyed under alkaline conditions and at lower temperature in the presence of electrolyte. The dye bath is then acidified to lower the pH and disperse dyes are added and the polyester fiber component of the blend is dyed at 120°C to 130°C.
US Patent No. 4,359,322 discloses a one bath process for dyeing cellulosic containing textile materials including polyester-cotton blends with fiber-reactive dyestuffs. In this process, the polyester-cotton blends are dyed with alkaline-stable disperse dyes and fiber reactive dyes at 40°C to 110°C to affect dyeing of the cotton portion of the blend with the fiber reactive dye component. The dye bath is held at 80°C for about 30 minutes to exhaust the fiber reactive dye into the cotton fiber. The dye bath is then heated at about 120°C to 140°C to dye the polyester portion of the blend with the alkali-stable disperse dye. Normal dye bath auxiliaries may be employed in the process; e.g. scouring agents, leveling aids, water softeners etc. However, 322' uses electrolyte/salt in the one bath process for dyeing polyester-cotton blends.
CN104074069 (A) discloses the one bath agent for reactive dye and disperse dye used in dyeing The one-bath agent consists of 50%-60% of pectinase, 35%-45% of cellulase, 3%-8% of surface active agent, 2%-3% of reactive dye protective agent, 1%-2% of alkaline fixing agent and 1%-2% of preservative. This one-bath agent facilitates fusion of the disperse dye and the reactive dye in short time.
JPH0860567 (A) demonstrate the single bath dyeing in the absence of or in the presence of small amount of alkali and electrolyte salt. Here, cellulosic material is modified with an amino group-bearing compound (for example, 2-oxo-1,3-oxazolidine or the like). The modified fiber is dyed at pH of 5-6 at 100°C to 210°C. The blend material with polyester fiber also can be dyed with the same reactive dyes through single bath dyeing at elevated temperature condition.
Polyester-cotton blends, if dyed in a single bath may lead to non-uniform dyeing. Further, dyeing strength depends upon the amount of electrolyte and alkali used in the dye bath as well as kind of dyes and their amount and kind of fibers to be dyed. Deep shades require more dye which in turn requires more electrolyte and more alkali.
Polyester-cotton blends, if dyed in a single bath may lead to non-uniform dyeing. Further, dyeing strength depends upon the amount of electrolyte and alkali used in the dye bath as well as kind of dyes and their amount and kind of fibers to be dyed. Deep shades require more dye which in turn requires more electrolyte and more alkali. The present conventional dyeing causes pollution due to high effluent generation, use of large quantity of electrolyte or salt, increase of colorant, chemical oxygen demand (COD), biological oxygen demand (BOD), total dissolved solids (TDS) and highly toxic chlorinated organic byproduct (AOX) in the stream. At the same time it consumes large quantity of water and energy. The existing art minimizes the use of electrolyte, reduces the water consumption and reduces the effluent generation.
Now-a-days, due to increased awareness of adverse effects on the environment competitiveness as well as cost competitiveness, industry and government are remarkably well concerned regarding the eco-friendly and efficient technological methods of dyeing due to increased pressure and demands claimed by the environmentalists, buyers and end users. As the adequate water resources are gradually diminishing alarmingly, all manufacturing plants including textile industries are trying to make best use of water by imparting process modifications due to environmental and commercial concerns as well.
Accordingly, there is a need to study and devise a method of dyeing which focuses on the reduction of water consumption, utility consumption, chemicals consumption, process time, effluent generation, costing of the dyeing, and lastly but significantly the reduction in pollution, keeping all the parameters as required.

OBJECTS OF THE INVENTION:
The main object of the invention is to provide a single bath dyeing method for a polyester-cotton blend material; wherein the material is pre-treated to scouring and cationization in a single pre-treatment bath, subsequent dyeing of the material using both disperse dyes and reactive dyes simultaneously in a single bath followed by acid reduction clearing.
Another object of the invention is to provide the single bath dyeing method for the polyester-cotton blend material; wherein the dyeing method reduces water consumption, effluent generation, waste disposal, man-power, energy consumption and number of steps of dyeing method; thereby making the process cost-effective and eco-friendly.
Yet another object of the invention is to provide the single bath dyeing method for the polyester-cotton blend material; wherein the dyeing method eliminates the use of electrolyte/salt and reduces effluent generation; thereby making the dyeing method eco-friendly.

SUMMARY OF THE INVENTION:
In the presently claimed invention, it is surprisingly found that the polyester-cotton blend textile material is dyed in the single bath having both reactive dyes and disperse dyes simultaneously depending upon the desired shade to be achieved at particular temperature and pH of the bath followed by acidic reduction clearing which is otherwise very difficult to dye polyester and cotton fiber components of the blend in single bath or leads to compromise in dye shade, uniform dyeing, and fastness properties of the material. The experiments were carried out to optimize temperature and pH of the bath and residence time of the material in the bath to dye polyester fiber component and cotton fiber component in the blended material in the single bath followed by acidic reduction clearing according to the invention. After the experimental, it was optimized to load dye bath with both disperse dyes and reactive dyes followed by adjustment of the temperature of the bath in the range of 80°C to 135°C followed by running the material in the bath for at least 25 to 50 minutes at pH in the range of 4 to 6 to dye polyester fiber component of the material, cooling the dye bath to 60°C followed by adding alkali to it to adjust the pH in the range of 9.5 to 11.5 and running the material in the bath for at least 25 to 60 minutes to dye cotton fiber component of the material followed by wash with water, neutralization, treatment with wash off agent, acid reduction clearing, hot wash and wash with water to obtain a dyed material having good color fastness to wash and to both wet rubbing and dry rubbing properties without sacrificing the color shade. The method of dyeing according to the invention eliminates the use of salt/electrolyte and reduces water consumption, effluent generation, time and number of the steps of dyeing which ultimately reduces energy, man power, etc, thereby reducing the overall cost of dyeing. The method of the presently claimed invention also reduces pollution, which is main advantage besides economic benefits. Thus method of dyeing of polyester-cotton blend of the invention is cost-effective and eco-friendly.
According to the method of the invention, there is provided a single bath dyeing method for a material of polyester-cotton blends;
the method comprising:
a) a pre-treatment comprising of scouring and cationization of the material in a single pre-treatment bath by suspending the material in water in a ratio of 1:5 to 8 (wt./vol.) followed by adding 10 to 60 gm/liter of cationizing agent and about 1/4th on the weight of cationizing agent of alkali to adjust pH of the bath in the range of 10 to 14 to obtain a cationized material;
b) subjecting the cationized material obtained in step (a) to a hot wash to obtain a washed cationized material;
c) subjecting the washed cationized material obtained in step (b) to a neutralization to obtain a neutralized cationized material;
d) subjecting the neutralized cationized material obtained in step (c) to a dyeing in a single bath comprising reactive dyes and disperse dyes in the presence of auxiliaries followed by adding alkali to the dye bath to dye a polyester fiber component and a cotton fiber component of the cationized material to obtain a dyed material;
e) subjecting the dyed material obtained in step (d) to a wash with water to obtain a washed dyed material;
f) subjecting the washed dyed material obtained in step (e) to a neutralization to obtain a neutralized dyed material;
g) subjecting the neutralized dyed material obtained in step (f) to a treatment with a wash off agent to obtain a treated dyed material;
h) subjecting the treated dyed material obtained in step (g) to an acid reduction clearing to obtain a treated dyed material;
i) subjecting the treated dyed material obtained in step (h) to a hot wash to obtain a washed dyed material; and
j) subjecting the washed dyed material obtained in step (i) to a wash with water to obtain a dyed material which is having good color fastness to wash and to both wet rubbing and dry rubbing properties without sacrificing the shade of the dyed color;
said method reduces water consumption, effluent generation, steps of dyeing, power consumption, energy consumption, cost of dyeing, waste disposal and pollution, thereby making the method cost-effective and eco-friendly.

Typically, the pre-treatment step (a) further comprises bleaching along with scouring and cationization of the material.
Typically, the step (b) comprises loading the cationized material obtained in step (a) and water in the bath, heating the bath to 75°C to 85°C, running the material in the bath for at least 8 to 15 minutes of residence time and draining the bath to obtain a washed cationized material.
Typically, the step (c) of neutralization comprises loading the washed cationized material obtained in step (b) and water in the bath, adding acid to the bath to adjust the pH of the bath in the range of 4 to 6, adding a core neutralizing agent to the bath, running the material in the bath for at least 8 to 15 minutes of residence time while maintaining the pH in the range of 4 to 6 and draining the bath to obtain a neutralized cationized material.
Typically, the step (d) comprises loading the neutralized cationized material obtained in step (c) and water in the bath, adding auxiliaries in the bath, maintaining the pH of the bath in the range of 4 to 6, heating the bath to 60°C, adding both reactive dyes and disperse dyes in the bath, raising the temperature of the dye bath to 90° C followed by heating to 135° C, running the material in the bath for at least 25 to 50 minutes of residence time to dye polyester fiber component of the material, cooling the bath to 60°C followed by adding alkali to it to adjust the pH in the range of 9.5 to 11.5, running the material in the bath for at least 25 to 60 minutes of residence time to dye cotton fiber component of the material and draining the bath to obtain a dyed material.
Particularly, the step (d) comprises loading the neutralized cationized material obtained in step (c) and water in the bath, adding auxiliaries in the bath, checking and maintaining the pH of the bath in the range of 4.5 to 5.5, heating the bath to 60°C, adding both reactive dyes and disperse dyes in the bath, raising the temperature of the bath to 90° C at the rate of 3°C/minute followed by raising the temperature from 90°C to 110°C at the rate of 2.5°C/minute further raising the temperature of the bath from 110°C to 130°C at the rate of 1.5°C /minute followed by running the material in the bath for at least 25 to 45 minutes of residence time to dye polyester fiber component of the material, cooling the bath from 130°C to 110°C at the rate of 1.5°C/minute followed by cooling the bath from 110°C to 90°C at the rate of 2.5°C/minute further cooling from 90°C to 60°C at the rate of 3°C/minute followed by adding weak alkali and subsequently strong alkali to it to adjust the pH in the range of 9.5 to 10.5, running the material in the bath for at least 25 to 50 minutes of residence time to dye cotton fiber component of the material and draining the bath to obtain the dyed material.
Typically, the step (e) of wash with water comprises loading the dyed material obtained in step (d) and water in the bath, running the material in the bath for at least 8 to 15 minutes of residence time at the temperature in the range of 25°C to 30°C and draining the bath to obtain a washed dyed material.
The step (e) may be repeated again.
Typically, the step (f) of neutralization comprises loading the washed dyed material obtained in step (e) and water in the bath followed by addition of acid to it to adjust the pH of the bath in the range of 4 to 6, adding a core neutralizing agent followed by running the material in the bath for 8 to 15 minutes of residence time while maintaining pH between 4 to 6 and draining the bath to obtain a neutralized dyed material.
Typically, the step (g) of treatment with wash off agent comprises loading the neutralized dyed material obtained in step (f) with water in the bath followed by adding a wash off agent in the bath, raising the temperature of the bath in the range of 80°C to 95°C, running the material in the bath for at least 10 to 20 minutes of residence time at the maintained temperature and draining the bath to obtain a treated dyed material.
Typically, the step (h) of treatment of acid reduction clearing comprises loading the treated dyed material obtained in step (g) and water in the bath, adding acid to it to adjust the pH in the range of 4 to 6.5 followed by adding a reduction clearing agent to the bath, heating the bath to 80°C, running the dyed material in the bath for 10 to 20 minutes of residence time at maintained temperature and draining the bath to obtain a treated dyed material.
Typically, the step (i) of treatment of hot wash comprises loading the treated dyed material obtained in step (h) and water in the bath, heating the bath to raise the temprature in the range of 75°C to 90°C followed by running the material in the bath for at least 8 to 15 minutes of residence time at maintained temperature and draining the bath to obtain a washed dyed material.
Typically, the step (j) of wash with water comprises loading the washed dyed material obtained in step (i) and water in the bath, running the material in water at temperature in the range of 25°C to 30°C for at least 8 to 15 minutes of residence time and draining the bath to obatin a washed dyed material.
The step (j) may be repeated again.
Optionally, washing the dyed material obtained in the step (j) with water.

Typically, the single bath dyeing method for polyester-cotton blends material which comprises single bath pre-treatment comprising scouring and cationization followed by dyeing polyester fibre component and cotton fibre component of the blend material simultaneously in the single bath followed by acid reduction clearing, reduces
• number of steps to 10,
• 25 to 35 % of fresh water consumption,
• 25 to 35 % of effluent generated and drained,
• 8 to 25 % of the total time consumption,
• 5 to 15 % of cost of dyeing; and
• eliminates the use of electrolyte/ salt;
thereby making the invention cost-effective and eco-friendly.

Typically, the dyed material of polyester-cotton blends obtained according to the invention have good color fastness to washing being rated 5 and to both dry rubbing and wet rubbing being rated 5 and 3 respectively.

DETAILED DESCRIPTION OF THE INVENTION:
The terms “a,” “an,” “the” and similar referents used in the context of describing the invention following claims are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it was individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.
Certain embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Of course, variations on these described embodiments will become apparent to those of ordinary skill in the art upon reading the description. The inventor expects skilled artisans to employ such variations as appropriate, and the inventor intend for the invention to be practiced otherwise than specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the below-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.
Specific embodiments disclosed herein can be further limited in the claims using consisting of or/and consisting essentially of language. When used in the claims, whether as filed or added per amendment, the transition term “consisting of excludes any element, step, or ingredient not specified in the claims. The transition term “consisting essentially of limits the scope of a claim to the specified materials or steps and those that do not materially affect the basic and novel characteristic(s). Embodiments of the invention so claimed are inherently or expressly described and enabled herein.
As used herein, the term "material" refers to fabric or fiber or yarn. The fabric or yarn is either woven or knitted or felted fabric/yarn made up of blends of the fibers of cotton with polyester.
As used herein, the terms "polyester-cotton blends" refers to fabric or fiber or yarn of cotton and polyester blending in different proportions as per the need. The fabric or yarn is either woven or knitted or felted fabric/yarn made up of blending the cotton fibers and polyester fibers.
As used herein, the term "cationizing agent" refers to any cationizing agent which introduces the cationic group on the surface of the cellulosic material that renders the material's cationic property and increases their affinity for anionic dyes.
As used herein, the term "weight percent (wt. %)" when used without qualification, typically refers to the weight percent of a particular solid component as compared with all solid components present in the reaction mixture.

DETAILED DESCRIPTION OF THE EMBODIMENTS:
In the following description, the embodiments are described in sufficient details to enable those skilled in the art to practice the invention. Other embodiments may be utilized and structural, logical and other changes may be made without departing from the spirit and scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense. The detailed description that follows begins with a definition section followed by a description of various embodiments of the invention. A series of examples are presented later followed by a brief conclusion.
Cotton cellulose material has excellent properties such as good moisture absorbency, comfortable to wear, and easy to dye. These properties makes cotton textiles very popular amongst us. Cotton is composed of 90-96% cellulose based on the weight of the fibers and 4% to 10% non-cellulosic components. The cotton fibers are naturally yellowish or brown in color.
The material used in the present invention is polyester-cotton blends in the ratio of 20:80 to 80:20. The fabric is having density of = 50 gsm and =1000 gsm.
The cotton fiber component being hydrophilic has affinity towards reactive dyes and the polyester fiber component being hydrophobic has affinity towards disperse dye. Generally, the dyeing of the cotton is carried out in alkaline pH and at lower temperature range of 60°C to 80°C in the presence of electrolyte/salt and dyeing of the polyester is carried out at acidic pH and at higher temperature range of 100°C to 130°C respectively. Due to this, the conventional process is carried out in two separate baths as single bath dyeing of polyester-cotton blend may lead to weak fastness properties and non-uniform or patchy dyeing. The conventional polyester dyeing is followed by alkali reduction clearing to improve fastness.

The conventional method used commercially for dyeing polyester-cotton blends consist of the following steps:
1. Grey Boiling: In grey boiling, the bath is filled up with polyester-cotton blend material to be dyed and water in 1:5 wt./vol. ratio along with auxiliaries comprising 0.7 gm/liter of Exhosperse HC, 1.0 gm/liter of Exowet ES and 0.5 gm/liter of Dep. ACA B-Liq. The bath is heated to 80°C and the material is run in the bath for 15 minutes. The bath is cooled to 78°C subsequently draining the bath after the treatment to obtain a treated material;
2. Polyester Dyeing: The bath is loaded with the treated material obtained in step (1) and water along with auxiliaries consisting of 2 gm/liter of Dep. ACA B-Liq., 1 gm/liter of sodium acetate, 1 gm/liter of Sunsoft LM7, 1.3 gm/liter of Levocol CWS and 1.0 gm/liter of acetic acid in the bath. The bath is heated to raise temperature to 60°C. The bath pH is checked and maintained between 4.5 to 5.5. After pH confirmation, the disperse dyes consisting of 0.002 % of Coralene brilliant red HP3BS and 2.250 % of Coralene black RLS are added to the bath over 20 minutes. The bath is heated to 130°C. When temperature of the bath reaches to 130°C, the material is run in the bath for 40 minutes. Further the bath is cooled to 80°C. A sample is tested for the shade of polyester dyed portion after carbonization treatment. Once carbonized cutting shade is matched with carbonized standard cutting shade, the bath is drained to obtain a dyed material;
3. Hot alkali reduction clearing: The dyed material obtained in step (2) and water are loaded in the bath. 4.0 gm / liter of sodium hydroxide and 4.0 gm /liter of sodium dithionite are added to the bath. The bath is heated to 80°C. The material is run in the bath for 20 minutes. The bath is cooled to 74°C. The bath is drained after the treatment to obtain a treated dyed material;
4. Hot alkali reduction clearing: The treated dyed material obtained in step (3) is again subjected to reduction clearing by following the step (3) to remove unused disperse dye. The bath is drained after treatment to obtain a treated dyed material;
5. Hot wash: The treated dyed material obtained in step (4) and water are loaded in the bath. The bath is heated to 80°C. The material is run in hot water at 80°C for 10 minutes. The bath is drained after wash to obtain a washed dyed material;
6. Neutralization: The washed dyed material obtained in step (5) and water are loaded in the bath. Acetic acid solution (33%) is added to the bath to adjust the pH of the bath between 5 to 6. The dyed material is run in the bath for 10 minutes by maintaining pH of the bath between 5 to 6. The bath is drained after neutralization to obtain a neutralized dyed material;
7. Cotton Dyeing: In the cotton dyeing, the bath is loaded with neutralized dyed material obtained in step (6) and water along with auxiliaries comprising 2.0 gm/liter of Dep. ACA B-Liq., 0.5 gm/liter of Albatex AB55, and 0.5 gm/liter of Orgakol TSP. The bath is heated to 50° C. The dyes consisting of 0.400 % of Corafix yellow ECO+, 1.32 % of Corafix red ECo+ and 7.830 % of Corafix Black GDE are added to the bath over 20 minutes at 50° C. The neutralized dyed material is run in the bath for 10 minutes. 60 gm/liter Glauber's salt is added in the bath over 40 minutes. The dyed material is run in the bath for 25 minutes. 6 gm/liter of sodium carbonate as first alkali is added in the bath over a period of 20 minutes followed by running the bath for 5 minutes. The second alkali, 1.9 gm/liter of caustic (NaOH) is added in the bath over 25 minutes followed by running the bath for 5 minutes to adjust the bath pH in the range of 9 to 10. The temperature of the bath is increased to 60°C followed by running the material in the bath for 40 minutes at 60° C to dye cotton fiber component of the material. The depth of the shade of the dyed material is checked by taking small window cutting. The bath is drained after dyeing to obtain a dyed material;
8. Wash with water: The dyed material obtained in step (7) and water are loaded in the bath. The dyed material is run in the bath for 10 minutes at the temperature in the range of 25°C to 30°C. The bath is drained after the wash to obtain a washed dyed material;
9. Wash with water: The washed dyed material obtained in step (8) and water are loaded in the bath. The dyed material is run in the bath for 10 minutes at the temperature in the range of 25°C to 30°C and the bath is drained after the wash to obtain a washed dyed material;
10. Neutralization: The washed dyed material obtained in step (9) and water are loaded in the bath. Acetic acid solution (33%) is added to the bath to adjust the pH of the bath between 4.5 to 5.5. 0.3 gm/liter of Invatex AC is added in the bath. The washed dyed material is run in the bath for 10 minutes by maintaining the pH between 4.5 to 5.5. The bath is drained after neutralization to obtain a neutralized dyed material;
11. Treatment with wash off agent: The neutralized dyed material obtained in step (10) and water are loaded in the bath. 2 gm/liter of wash off agent, Diakol ECO is added in the bath. The bath is heated to raise the temperature of the bath to 95°C. The material is run in the bath for 15 minutes at the maintained temperature. The bath is drained after the treatment to obtain a treated dyed material;
12. Hot wash: The treated dyed material obtained in step (11) and water are loaded in the bath. The bath is heated to 85°C. The dyed material is run in hot water at 85°C for 10 minutes in the bath. The bath is drained after wash to obtain a washed dyed material;
13. Wash with water: The dyed material obtained in step (12) and water are loaded in the bath. The dyed material is run in the bath for 10 minutes at the temperature in the range of 25°C to 30°C. The bath is drained after wash to obtain a washed dyed material; and
14. Dye-fixing: The washed dyed material obtained in step (13) and water are loaded in the bath. 1.5 gm/liter of Albafix WFF is added in the bath. The dyed material is run in the bath for 10 minutes. The bath is drained after treatment to obtain a dyed material.

Thus, there are minimum 14 steps involved in the conventional dyeing method by using salt.
To dye 130 Kg of polyester-cotton blend by conventional dyeing method using salt/ electrolyte, the method has the followings
• 14 steps involved;
• the cost is around Rs. 18,334/-;
• the total water consumption is around 5213 Liters;
• the total time consumption is around 12 Hours;
• the effluent generated is around 4823 Liters; and
• the total salt consumption is around 39 Kg.

There is another conventional method of dyeing a polyester-cotton blends material by cationization consisting of the following steps:
i. subjecting the material to hot boiling in the presence of auxiliaries to obtain a treated material;
ii. subjecting the treated material obtained in step (i) to a pre-treatment comprising scouring and cationization in the presence of alkali to adjust the pH in the range of 9 to 14 to obtain a cationized material;
iii. subjecting the cationized material obtained in step (ii) to hot wash treatment to obtain a washed cationized material;
iv. subjecting the washed cationized material obtained in step (iii) to neutralization treatment to obtain a neutralized cationized material;
v. subjecting the neutralized cationized material obtained in step (iv) to a polyester dyeing in a bath comprising disperse dyes and auxiliaries to dye a polyester fiber component of the material to obtain a cationized dyed material;
vi. subjecting the cationized dyed material obtained in step (v) to a reduction clearing to obtain a treated cationized dyed material;
vii. subjecting the treated cationized dyed material obtained in step (vi) to hot wash treatment to obtain a washed cationized dyed material;
viii. subjecting the washed cationized dyed material obtained in step (vii) to neutralization treatment to obtain a neutralized cationized dyed material;
ix. subjecting the neutralized cationized dyed material obtained in step (viii) to wash with water treatment to obtain a washed cationized dyed material;
x. subjecting the washed cationized dyed material obtained in step (ix) to cotton dyeing in a bath comprising reactive dyes, auxiliaries, and alkali to dye a cotton fiber component of the cationized dyed material to obtain a dyed material;
xi. subjecting the dyed material obtained in step (x) to wash with water treatment to obtain a washed dyed material;
xii. subjecting the washed dyed material obtained in step (xi) to neutralization treatment to obtain a neutralized dyed material;
xiii. subjecting the neutralized dyed material obtained in step (xii) to treatment with wash off agent to obtain a treated dyed material;
xiv. subjecting the treated dyed material obtained in step (xiii) to hot wash to obtain a washed dyed material; and
xv. subjecting the washed dyed material obtained in step (xiv) to wash with water to obtain a dyed material;
to obtain the dyed material having color fastness properties to wash as well as rubbing and shade of the color as desired by the requirement.

The above-referred conventional the method of dyeing for 130 kg of the material of polyester-cotton blends results into
• the number of steps : 15;
• the cost of the dyeing is around Rs. 19916/-;
• the total water consumption is around 5564 Liters;
• the total time consumption is around 10 Hour 42 minutes; and
• the effluent generated is around 5170 Liters.

The main objective of the present invention is to eliminate the use of electrolyte/salt and also to reduce number of steps of dyeing, water consumption, effluent generation, dyeing cost, energy consumption, man-power consumption, etc.

The presently claimed invention is directed to a cost-effective and eco-friendly method of dyeing a polyester-cotton blend material.
In the presently claimed invention, the method consisting of:
a) The polyester-cotton blend material is first subjected to a pre-treatment comprising of scouring and cationization in a single pre-treatment bath. The polyester-cotton blend material and water are loaded in the bath. 10 to 60 gm/liter of cationizing agent is added to the bath. 1/4th on the weight of cationizing agent of alkali is added to the bath to adjust the pH of the bath in the range of 10 to 14. The material is run in the bath and the bath is drained to obtain a cationized material;
b) The cationized material obtained in step (a) is subjected to a hot wash to obtain a washed cationized material;
c) The washed cationized material obtained in step (b) is subjected to a neutralization to obtain a neutralized cationized material;
d) The neutralized cationized material obtained in step (c) is subjected to a dyeing in a single dye bath comprising reactive dyes and disperse dyes in the presence of auxiliaries followed by adding alkali to obtain a dyed material;
e) The dyed material obtained in step (d) is subjected to a wash with water to obtain a washed dyed material;
f) The washed dyed material obtained in step (e) is subjected to a neutralization to obtain a neutralized dyed material;
g) The neutralized dyed material obtained in step (f) is subjected to a treatment with wash off agent to obtain a treated dyed material;
h) The treated dyed material obtained in step (g) is subjected to an acid reduction clearing to obtain a treated dyed material;
i) The treated dyed material obtained in step (h) is subjected to a hot wash to obtain a washed dyed material; and
j) The washed dyed material obtained in step (i) is subjected to a wash with water to obtain a dyed material which is having good color fastness to wash and to both wet rubbing and dry rubbing properties without sacrificing shade of the dyed color;
said method reduces water consumption, effluent generation, steps of dyeing, power consumption, energy consumption, cost of dyeing, waste disposal and pollution, thereby making the method cost-effective and eco-friendly.

The presently claimed method optionally may repeat step (e) an (j).
Scouring treatment removes components including wax, pectin, protein, etc. and improves bleaching and acceptability of dye by the material. Scouring comprises alkali treatment to material mostly at higher temperature, particularly temperature above 60°C. Scouring, in common practice, involves boiling the material in 2 to 3 gm/liter of sodium hydroxide (pH in the range of 10 to 14) in the presence of surfactants or wetting agents for about 30 to 60 minutes. Upon completion, it is washed with plentiful amount of water. Scouring helps to improve the water absorbency and the appearance of the material becomes clean and soft.
Particularly, the wetting agents or surfactants used are selected from the group consisting of low foaming alkali stable wetting agents or surfactants including nonionic alcohol, EO/PO adducts, alkyl end capped phenol and the likes.
However, natural color of cotton material is not removed in the scouring process. To meet the whiteness requirement, the material is subjected to bleaching. Hydrogen peroxide is an environmentally safe bleaching agent for the material. The bleaching of the material is carried out by treating it with hydrogen peroxide in an alkaline medium, stabilizer, and either at high temperatures, particularly at 90°C to 110°C or at a long dwell time (approximately 30 to 60 minutes). Approximately 2 to 3 gm/liter of caustic soda is used in bleaching to adjust the pH of the bath in the range of 10.5 to 10.8. Upon completion of the bleaching process, it is first neutralized and washed subsequently with plentiful amount of water. The bleaching is optional and need to be carried out only when there is whiteness requirement.
Particularly, the stabilizer used is selected from the group consisting of organic stabilizers such as pentasodium diethylenetriamine penta acetic acid, amino tri-(methylene phosphonic acid), saccharide-acrylate copolymers with carboxylic acids and the likes.

Typically, step (a) comprises pre-treatment consisting of scouring and cationization simultaneously, wherein the step (a) comprises loading water and the polyester-cotton blend material in a bath followed by adding auxiliaries, raising the temperature of the bath to 60°C, adding 1/4th on the weight of cationizing agent of alkali to adjust the pH of the bath in the range of 10 to 14, running the bath for at least 10 to 30 minutes, adding 30 to 60 gm/liter of cationizing agent to the bath followed by running the bath for at least 10 minutes, raising the temperature of the bath to 85°C at the rate of 3°C/min followed by running the material in the bath for at least 45 minutes of residence time, and cooling the bath to 80°C subsequently draining the bath to obtain a cationized blend material.
Particularly, the wetting agents or surfactants used in step (a) are selected from the group consisting of low foaming alkali stable wetting agents or surfactants including nonionic alcohol, EO/PO adducts, alkyl end capped phenol and the likes.
Typically, auxiliaries used in step (a) are selected from polymeric dispersing agent such as Exhosperse HC, wetting agent such as Exowet ES, anionic and nonionic lubricating agent such as Dep. ACA B-Liq.
The cationizing agent is selected from 3-chloro-2-hydroxypropyl trimethyl ammonium chloride (CHPTMAC).
Typically, the alkali is selected from sodium hydroxide, potassium hydroxide and the likes.
Typically, step (a) further comprises bleaching along with scouring and cationization of the material by adding 1 to 8 gm/liter of hydrogen peroxide.
The bleaching of the material is carried out in the presence of stabilizer.
Particularly, the stabilizer used in step (a) is selected from the group consisting of organic stabilizers such as pentasodium diethylenetriamine penta acetic acid, amino tri (methylene phosphonic acid), saccharide-acrylate copolymers with carboxylic acids and the likes. The stabilizer used in step (a) of the present invention is Chel DTPA-41 Liq. (Pentasodium pentetate based).
Typically, the material to be dyed and water used in step (a) is in the ratio of 1:5 to 8, particularly 1:5 (wt./vol.).

In one of the embodiments of the invention, the step (b) of hot wash comprises loading the cationized blend material obtained in step (a) and water in a ratio of 1:2 to 5 (wt./vol.) in a bath. The bath is heated to raise the temperature of the bath in the range of 75°C to 85°C. The material is run in the bath for at least 8 to 15 minutes of residence time at the temperature in the range of 75°C to 85°C. The bath is drained to obtain a washed cationized material.
In a preferred embodiment of the invention, the step (b) comprises loading the cationized blend material obtained in step (a) and water in a ratio of 1:2 to 3 (wt./vol.) in the bath. The bath is heated to 80°C and the material is run in the bath for at least 10 minutes of the residence time at 80°C. The bath is drained after wash to obtain the washed cationized material.

In one of the embodiments of the invention, the step (c) comprises loading the washed cationized material obtained in step (b) and water in a ratio of 1:2 to 5 (wt./vol.) in the bath. Acid is added to the bath to adjust the bath pH in the range of 4 to 6. A core neutralizing agent is added in the bath. The cationized material is run in the bath for at least 8 to 15 minutes of the residence time while maintaining the pH in the range of 4 to 6. The bath is drained to obtain a neutralized cationized material
The acid used in the neutralization in step (c) is selected from acetic acid, citric acid, formic acid and the likes.
The core neutralizing agent used in step (c) is selected from blend of non volatile organic acids such as Invatex AC.
In a preferred embodiment of the invention, the step (c) comprises loading the washed cationized blend material obtained in step (b) and water in the ratio of 1:2 to 3 (wt./vol) in the bath followed by adding 2 gm/liter of acetic acid to the bath to adjust the bath pH in the range of 4.5 to 5.5, adding 1 gm/liter of core neutralizing agent, Invatex AC, in the bath, running the cationized material in the bath for at least 10 minutes of residence time while maintaining the pH in the range of 4.5 to 5.5 and draining the bath after completion of neutralization to obtain the neutralized cationized material.

In one of the embodiments of the invention, the neutralized cationized material obtained in step (c) is then subjected to dyeing in step (d) in a single bath. The neutralized cationized material obtained in step (c) and water are loaded in a ratio of 1:2 to 5 (wt./vol.) in the bath. Auxiliaries are added in the bath. The pH of the bath is checked and maintained in the range of 4 to 6. The bath is heated to 60°C. Both reactive dyes and disperse dyes are added to the bath. The bath is heated to a temperature in the range of 90°C to 135°C. The cationized material is run in the bath for at least 25 to 50 minutes of residence time to dye polyester fiber component of the material. The bath is cooled to 60°C followed by adding alkali to it to adjust the pH in the range of 9.5 to 11.5. The material is run in the bath for at least 25 to 60 minutes of residence time to dye cotton fiber component of the material. The bath is drained to obtain a dyed material.
In the preferred embodiment of the invention, the step (d) consists of: the neutralized cationized material obtained in step (c) and water are loaded in a ratio of 1:2 to 3 (wt./vol.) in the bath. The auxiliaries are added in the bath. The pH of the bath is checked and maintained in the range of 4.5 to 5.5. The bath is heated to 60°C. Both reactive dyes and disperse dyes are added to the bath. The temperature of the dye bath is raised to 90° C at the rate of 3°C /minute followed by raising the temperature from 90°C to 110°C at the rate of 2.5°C/minute further raising the temperature of the bath from 110°C to 130°C at the rate of 1.5°C /minute. The material is run in the bath for at least 25 to 45 minutes of residence time to dye polyester fiber component of the material. The bath is cooled from 130°C to 110°C at the rate of 1.5°C/minute followed by cooling the bath from 110°C to 90°C at the rate of 2.5°C/minute further cooling from 90°C to 60°C at the rate of 3°C/minute. Weak alkali and subsequently strong alkali are added to the bath to adjust the pH in the range of 9.5 to 10.5. The material is run in the bath for at least 25 to 50 minutes of residence time to dye cotton fiber component of the material. The dye bath is drained to obtain the dyed material.
The auxiliaries used in step (d) are selected from lubricating agent such as Dep. ACA B-Liq. and the likes; dye bath conditioner such as Sunsoft LM7, Albatex AB55 and the likes; dispersing agent such as Levocol CWS and the likes; pH regulator such as acetic acid and the likes; buffer such as sodium acetate, Orgakol TSP, and the likes.
The reactive dyes used in step (d) are selected from ME and HE class of reactive dyes. The dyes are used either alone or in combination depending upon the desired shade. For example, to achieve black color, Corafix yellow ECO+, Corafix red ECo+, and Corafix Black GDE may be used in a specific proportion.
The disperse dyes used in step (d) are selected from anthraquinonoid and azo-based disperse dyes. These dyes are also used either alone or in combination depending upon the desired shade. For example, to achieve black color, Coralene brilliant red HP3BS and Coralene black RLS may be used in a specific proportion.
The weak alkali used in step (d) is selected from sodium bicarbonate and the likes. The strong alkali used in step (d) is selected from sodium hydroxide, potassium hydroxide and the likes.

In one of the embodiments of the invention, the step (e) of wash with water comprises of: the dyed material obtained in step (d) and water are loaded in the ratio of 1:2 to 5 (wt./vol.) in the bath. The dyed material is run in the bath for at least 8 to 15 minutes of the residence time at the temperature in the range of 25°C to 30°C. The bath is drained to obtain a washed dyed material.
In the preferred embodiment of the invention, the step (e) comprises of: the dyed material obtained in step (d) and water are loaded in the ratio of 1:2 to 3 (wt./vol.) in the bath. The material is run in the bath for at least 10 minutes of the residence time at the temperature in the range of 25°C to 30°C. The bath is drained to obtain the washed dyed material.
This step (e) may be repeated again.

In one of the embodiments of the invention, the step (f) of neutralization comprises loading the washed dyed material obtained in step (e) and water in the ratio of 1:2 to 5 (wt./vol.) in the bath followed by addition of acid to the bath to adjust the pH in the range of 4 to 6, adding a core neutralizing agent followed by running the material in the bath for 8 to 15 minutes of residence time while maintaining pH between 4 to 6 and draining the bath after treatment to obtain a neutralized dyed material.
The acid used in the neutralization in step (f) is selected from acetic acid, citric acid, formic acid and the likes.
The core neutralizing agent used in step (f) is selected from blend of non-volatile organic acids such as Invatex AC.
In a preferred embodiment of the invention, the step (f) of neutralization consisting of: the bath is loaded with the washed dyed material obtained in step (e) and water in the ratio of 1:2 to 3 (wt./vol.). The acetic acid solution (33%) is added to the bath to adjust the pH in the range of 4.5 to 5.5. 5 gm/liter of core neutralizing agent, Invatex AC, is added in the bath. The material is run in the bath for at least 10 minutes of residence time while maintaining the pH between 4.5 to 5.5. The bath is drained upon completetion of the neutralization step (f) to obtain the neutralized dyed material.

In one of the embodiments of the invention, the step (g) of treatment with wash off agent comprises loading the neutralized dyed material obtained in step (f) and water in the ratio of 1:2 to 5 (wt./vol.) in the bath followed by adding a wash off agent in it, heating the bath to raise the temperature in the range of 80°C to 95°C, running the material in the bath for at least 10 to 20 minutes of residence time at the maintained temperature and draining the bath to obtain a treated dyed material.
Typically, the wash off agent is selected from acrylic polymeric based washing off agents such as Diakol ECO and the likes.
In a preferred embodiment of the step (g) of the present invention, the bath is loaded with the neutralized dyed material obtained in step (f) and water in the ratio of 1:2 to 3 wt./vol. 2 gm/liter of wash off agent namely Diakol ECO is added to the bath. The bath is heated to raise the temperature to 95°C. The material is run in the bath at the maintained temperature for at least 15 minutes of residence time. The bath is drained after completion of the step (g) to obtain the treated dyed material.

In one of the embodiments of the invention, the treated dyed material obtained in step (g) is then subjected to acid reduction in step (h). In this step, the bath is loaded with the treated dyed material obtained in step (g) and water in the ratio of 1:2 to 5 (wt./vol.). The acid is added to the bath to adjust the pH in the range of 4 to 6.5 followed by adding a reduction clearing agent to the bath. The bath is heated to 80°C and the material is run in the bath for 10 to 20 minutes of residence time at maintained temperature. The bath is drained to obtain a treated dyed material.
In the preferred embodiment of the invention, the step (h) comprises loading the treated dyed material obtained in step (g) and water in the ratio of 1:2 to 3 wt./vol in the bath, adding acid to the bath to adjust the pH in the range of 4.5 to 5.5 followed by adding 2 to 6 gm/liter of reduction clearing agent to the bath, heating bath to raise the temperature to 80°C, running the material in the bath for at least 15 minutes of residence time at maintained temperature and draining the bath to obtain the treated dyed material.
The acid clearing agent is selected from sulfinic acid derivatives such as Cyclanon ECO and the likes.

In another embodiment of the invention, the step (i) comprises: the treated dyed material obtained in step (h) and water are loaded in the ratio of 1:2 to 5 (wt./vol.) in the bath. The bath is heated to raise the temperature in the range of 75°C to 90°C. The material is run in the bath for at least 8 to 15 minutes of the residence time at maintained temperature in the bath. The bath is drained after wash to obtain a washed dyed material.
In a preferred embodiment of the invention, the step (i) comprises loading the treated dyed material obtained in step (h) and water in the ratio of 1:2 to 3 (wt./vol.) in the bath, heating the bath to raise the temperature to 80°C followed by running the material in the bath for at least 10 minutes of the residence time at 80°C in the bath and draining the bath after wash to obtain the washed dyed material.

In one of the embodiments of the invention, the step (j) comprises: the washed dyed material obtained in step (i) and water are loaded in a ratio of 1:2 to 5 (wt./vol.) in the bath. The material is run in the bath for at least 8 to 15 minutes of the residence time at the temperature in the range of 25°C to 30°C in the bath. The bath is drained to obtain a dyed material.
In the preferred embodiment of the invention, the step (j) comprises loading the dyed material obtained in step (i) and water in a ratio of 1:2 to 3 (wt./vol.) in the bath, running the material in the bath for at least 10 minutes of the residence time at 25°C and draining the bath to obtain the dyed material.
This step (j) may be repeated again.

Optionally, the dyed material is washed with water.

According to the present invention, the single bath dyeing method for 130 Kg of polyester-cotton blends material which comprises single bath pre-treatment consisting of scouring and cationization, single bath dyeing followed by acid reduction clearing; the method reduces
• number of steps to 10,
• the cost of the dyeing is around Rs. 17,201/-;
• the total water consumption is around 3809 Liters;
• the total time consumption is around 9 Hours 32 minutes;
• the effluent generated is around 3419 Liters; and
• eliminates use of electrolyte/ salt;
thereby making the invention cost-effective and eco-friendly.

Against conventional dyeing method of polyester-cotton blend material, the presently claimed invention reduced the followings:
• number of steps to 10,
• 25 to 35 % of fresh water consumption,
• 25 to 35 % of effluent generated and drained,
• 8 to 25 % of the total time consumption,
• 5 to 15 % of cost of dyeing; and
• eliminated the use of sodium sulfate decahydrate (glauber's salt).
Thus, the method of single bath dyeing of presently claimed invention is cost-effective and eco-friendly.
The presently claimed invention may reduce effluent generation further by recycling the residual pre-treatment baths remained at the end of step (a) in a subsequent pre-treatment step (a).
The presently claimed invention intend to eliminate the use of two separate dyeing baths comprising reactive dyes and disperse dyes respectively to dye polyester-cotton blend material in separate steps and also to eliminate the use of sodium dithionite and alkali for alkaline reduction clearing which leads to pollution.
In the presently claimed invention, conditions of and quantities of the raw materials used in the pre-treatment, the dyeing and the acid reduction clearing are optimized after examining the material properties including whiteness, water absorbance, diffusion time, capillary effect, surface morphology, and thermal properties, as well as dye fixation, color yield, and color fastness properties.
In one of the embodiments of the invention, the polyester-cotton blend is dyed by following the method according to the present invention except step (h) of acid reduction clearing (i.e. eliminating step (h)).
The dyed polyester-cotton blend materials A, B, C and D prepared according to the conventional method using the salt, the another conventional method using the cationization, according to the method of the present invention and according to the method of the present invention except step (h) of acid reduction clearing (i.e. eliminating the step (h)) respectively are tested for the color fastness properties i.e. color fastness to wash and color fastness to rubbing.
The test of color fastness to wash is carried out by ISO 105-C06: A2S while that of the dry and wet rubbing fastness properties is carried out by ISO 105-x12 respectively.
Surface smoothness is one of the important qualities and requirements imposed by the consumer. As clothing remains next to human skin, it is very sensitive issue to ensure this quality properly. The surface smoothness of the blend material is scrutinized manually. The surface of the dyed material according to the invention is found satisfactorily fine with no mentionable changes.

Color fastness to wash:
The color fastness properties to wash of dyed fabric samples A, B, C and D are tested and compared with each other. The rating of color staining to Cotton/ Nylon/ Polyester/ Acrylic/ Wool for the dyed materials A, B and D is being rated 4. On the other hand, unpredictably the color staining to cotton for the dyed material C is rated 5. Analyzing the color fastness to wash results of all three materials are illustrated in Table 1.

TABLE 1
Rating of color fastness properties to wash properties
Samples Staining to Wash Fastness Rating
Polyester-cotton blend of sample A Cotton 4
Nylon 4
Polyester 4
Acrylic 4
Wool 4
Polyester-cotton blend of sample B Cotton 4
Nylon 4
Polyester 4
Acrylic 4
Wool 4
Polyester-cotton blend of sample C Cotton 5
Nylon 5
Polyester 5
Acrylic 5
Wool 5
Polyester-cotton blend of sample D Cotton 4
Nylon 3 to 4
Polyester 3 to 4
Acrylic 4
Wool 4

Color fastness to rubbing:
The color fastness properties to both dry and wet rubbing of dyed fabric samples A, B, C and D are tested and compared with each other. The ratings of color staining in this regard are interestingly found to be 5 and 3 for the sample C in case of dry and wet rubbing respectively. The results of color fastness to both dry and wet rubbing for the samples A to D are depicted in the Table 2.

TABLE 2
Rating of color fastness to both dry and wet rubbing properties

Samples Staining to Dry Rubbing Wet Rubbing
Polyester-cotton blend of sample A Standard rubbing cloth
4 2
Polyester-cotton blend of sample B 4 2
Polyester-cotton blend of sample C 5 3
Polyester-cotton blend of sample D 4 2

Thus, the present invention improves color fastness properties of dyed polyester-cotton blend.
The present invention is illustrated by the following example, which is not intended to limit the effective scope of the invention.

Example 1:
Conventional Process of dyeing of polyester-cotton blend material (without cationization and with Glauber's Salt)
The polyester-cotton blend (80:20) Knit PC Fleece construction having 270-280 gsm (Sample A) was used herein.
1. Grey Boiling: The material (130 Kg) was loaded in the bath and further it was filled up with 650 liters of water. The auxiliaries including Exhosperse HC (0.7 gm/liter), Exowet ES (1 gm/liter) and Dep. ACA B-Liq. (0.5 gm/liter) were added. The bath was heated to raise the temperature to 80°C and the material was run in the bath for 15 minutes. The bath was cooled to 78°C and it was drained to obtain a treated material.
2. Polyester Dyeing: The bath was loaded with the treated material obtained in step (1) and 351 liters of water. The auxiliaries inclduing Dep. ACA B-Liq. (2 gm/liter), sodium acetate (1 gm/liter), Sunsoft LM7 (1 gm/liter), Levocol CWS (1.30 gm/liter) and acetic acid (1 gm/liter) were added to the bath. The bath was heated to 60°C. The bath pH was adjusted and maintained between 5 to 5.5. The disperse dyes namely Coralene brilliant red HP3BS (0.002%) and Coralene black RLS (2.250%) were added to the bath over 20 minutes. The bath was heated to 90°C at the rate of 2.5°C/minute followed by heating the bath from 90°C to 130°C at the rate of 1.5°C/minute. The material was run in the bath at 130°C for 40 minutes. The bath was cooled from 130°C to 90°C at the rate of 1.5°C/minute followed by cooling the bath from 90°C to 74°C at the rate of 2.5°C/minute. The carbonized cutting shade of material was matched with carbonized standard cutting shade. Upon matching, the bath was drained to obtain a dyed material.
3. Hot alkali reduction clearing: The bath was loaded with the dyed material obtained in step (2) and 351 liters of water. Sodium dithionite (4 gm/liter) and sodium hydroxide (4 gm /liter) were added to the bath. The bath was heated to 80°C. The material was run in the bath for 20 minutes. The bath was cooled to 74°C. The bath was drained after treatment to obtain a treated dyed material.
4. Hot reduction clearing: The treatment of hot reduction clearing was repeated as per step (3) and the bath was drained after the treatment to obtain a treated dyed material.
5. Hot wash: The bath was loaded with the treated dyed material obtained in step (4) and 351 liters of water. The bath was heated to 80°C. The material was run in the bath at 80°C for 10 minutes. The bath was drained after treatment to obtain a washed dyed material.
6. Neutralization: The bath was loaded with the washed dyed material obtained in step (5) and 351 liters of water. Acetic acid solution (33%) as neutralizaing agent was added to the bath to adjust bath pH between 5.5 to 6. The bath was run for 10 minutes while maintaining pH between 5.5 to 6. The bath was drained after treatment to obtain a neutralized dyed material.
7. Cotton Dyeing: The bath was loaded with the neutralized dyed material obtained in step (6) and 351 liters of water. The auxiliaries inclduing Dep. ACA B-Liq.(2.0 gm/liter), Albatex AB55 (0.5 gm/liter), and Orgakol TSP (0.5 gm/liter) were added to the bath. The bath was heated to 50°C. The disperse dyes namely Corafix yellow ECO+ (0.400%), Corafix red ECo+ (1.32 %) and Corafix Black GDE (7.830 %) were added to the bath over 20 minutes at 50°C. The neutralized dyed material was run for 10 minutes. Glauber's salt (60 gm/lit.) was added in the bath over 40 minutes. The material was run in the bath for 25 minutes. Sodium carbonate (6 gm/liter) was added to the bath over 20 minutes. The bath was run for 5 minutes. Sodium hydroxide (1.90 gm/liter) was added to the bath over 25 minutes and it was run for 5 minutes to adjust its pH to 9.5 to 10. The bath was heated from 50°C to 60°C. The material was run in the bath at 60°C for 40 minutes. The shade cutting of the material was checked and compared with standard shade cutting. Upon depth match, the bath was drained to obtain a dyed material.
8. Wash with water: The bath was loaded with the dyed material obtained in step (7) and 351 liters of water. The material was run in the bath for 10 minutes at maintained temperature of 25°C. The bath was drained after treatment to obtain a washed dyed material.
9. Wash with water: The washed dyed material obtained in step (8) was again subjected to treatment of wash with water as per step (8) and the bath was drained after the treatment to obtain a washed dyed material.
10. Neutralization: The bath was loaded with the washed dyed material obtained in step (9) and 351 liters of water. Acetic acid solution (33%) as neutralizaing agent was added to the bath to adjust the pH between 5 to 5.5. 0.3 gm/liter of Invatex AC was added in the bath and it was run for 10 minutes while maintaining pH between 5 to 5.5. The bath was drained after treatment to obtain a neutralized dyed material.
11. Treatment with wash off agent: The bath was loaded with the neutralized dyed material obtained in step (10) and 351 liters of water. Diakol ECO (2 gm/liter) was added to the bath over 5 minutes. The bath was heated to 95°C and the material was run in the bath for 15 minutes at maintained temperature. The bath was drained upon treatment to obtain a treated dyed material.
12. Hot wash: The bath was loaded with the treated dyed material obtained in step (11) and 351 liters of water. The bath was heated to 85°C. The material was run in the bath for 10 minutes at 85°C. The bath was drained after treatment to obtain a washed dyed material.
13. Wash with water: The bath was loaded with the washed dyed material obtained in step (12) and 351 liters of water. The material was run in the bath for 10 minutes at 25°C. The bath was drained after treatment to obtain a washed dyed material.
14. Dye-fixing: The bath was loaded with the washed dyed material obtained in step (13) and 351 liters of water. Albafix WFF (1.50 gm/liter) was added in the bath. The material was run in the bath for 10 minutes and the bath was drained after the treatment to obtain a dyed material.
RESULTS:
• number of steps: 14
• the cost was around Rs. 18,334/-;
• the total water consumption was around 5213 Liters;
• the total time consumption was around 12 Hours;
• the effluent generated was around 4823 Liters; and
• the total salt consumption was around 39 Kg.
• Depth of the black color: 100% with standard sample (STD).
• Surface smoothness of the dyed material was scrutinized manually and it was found satisfactorily fine with no mentionable changes.
• Color fastness properties
The dyed polyester-cotton blend materials "A" prepared according to example 1 was tested for the color fastness properties i.e. color fastness to wash and color fastness to rubbing by ISO 105-C06: A2S and ISO 105-x12 respectively.
• The color fastness property to wash of dyed fabric sample A was tested and rating of color staining to Cotton/ Nylon/ Polyester/ Acrylic/ Wool for the dyed material A was being rated 4.
• The color fastness properties to both dry and wet rubbing of dyed fabric sample A was tested and color fastness to both dry and wet rubbing for the sample A was being rated 4 and 2 respectively.

Reference Example 2:
Conventional method of dyeing of polyester-cotton blend
The polyester-cotton blend (80:20) Knit PC Fleece construction having 270-280 gsm (SAMPLE "B") was used herein.
i. Hot Boiling: The material (130 Kg ) was loaded in the bath. The bath was filled up with 650 liters of water and the auxiliaries including Exhosperse HC (0.7 gm/liter), Exowet ES (1 gm/liter) and Dep. ACA B-Liq. (0.5 gm/liter) were added in the bath. The temperature of the bath was raised to 90°C and the material was run in the bath for 10 minutes. The bath was cooled to 78°C and it was drained to obtain a treated material.
ii. Pre-treatment (scouring and cationization in a single bath): Machine bath was loaded with the treated material obtained in step (i) and 351 liters of water. To this, auxiliaries namely 0.70 gm/liter of Exhosperse HC, 1 gm/liter of Exowet ES, and 0.5 gm /liter of Dep. ACA B-Liq. were added. The bath was heated to raise the temperature to 60°C. The material was run in the bath for 10 minutes. To this bath, 9.75 Kg of caustic soda was added at 60°C to adjust the bath pH to 11 to 11.5 and the bath was run for 10 minutes. 39 Kg of cationizing agent, 3-chloro-2-hydroxypropyl trimethyl ammonium chloride (Rishlyte® 9098) was added to the bath at 60°C in 10 minutes and the bath was allowed to run for 3 minute. The temperature of the bath was increased to 85°C by 3°C/minute. Cationization was carried out at 85°C by running the material in the bath for 45 minutes. The bath was cooled to 78°C in 5 minutes. The bath was drained to obtain a cationized material.
iii. Hot wash: Machine bath was loaded with the cationized material obtained in step (ii) and 351 liters of water. The bath was heated to 80°C. The cationized material was run in the bath for 10 minutes. The bath was drained after treatment to obtain a washed cationized material.
iv. Neutralization: Machine bath was loaded with the washed cationized material obtained in step (iii) and 351 liters of water. Acetic acid solution (33%) as neutralizaing agent was added to the bath to adjust the bath pH between 5 to 5.5. 0.5 gm /liter of Invatex AC was added to the bath. The cationized materal was run in the bath for 10 minutes while maintaining the pH between 5 to 5.5. The bath was drained after treatment to obtain a neutralized cationized material.
v. Polyester Dyeing: Machine bath was loaded with the neutralized material obtained in step (iv) and 351 liters of water. The auxiliaries inclduing ACA B-Liq. (2 gm/liter), sodium acetate (0.5 gm/liter), Sunsoft LM7 (0.7 gm/liter), Levocol CWS (1.3 gm/liter) and acetic acid (1 gm / liter) were added to the bath. The pH of the bath was adjusted and maintained between 5 to 5.5. The bath was heated to 60°C. The disperse dyes namely Coralene Brilliant Red HP3BS (0.002%) and Coralene Black RLS (2.25%) were added to the bath over 20 minutes. The bath was heated to 90°C at the rate of 2.5°C/minute followed by heating bath from 90°C to 130°C at the rate of 1.5°C/minute. The material was run in the bath at 130°C for 40 minutes. The bath was cooled from 130°C to 90°C at the rate of 1.5°C/minute followed by cooling the bath from 90°C to 74°C at the rate of 2.5°C/minute. The carbonized cutting shade of material was matched with carbonized standard cutting shade. Upon matching of the shade, the bath was drained to obtained a cationized dyed material.
vi. Hot reduction clearing: Machine bath was loaded with the cationized dyed material obtained in step (v) and 351 liters of water. Sodium dithionite (4 gm/liter) and caustic (4 gm/liter) were added over 8 minutes. The bath was heated to 80°C over 6 minutes. The cationized dyed material was run in the bath for 10 minutes. The bath was drained after treatment to obtain a washed cationized dyed material.
vii. Hot wash: Machine bath was loaded with the washed cationized dyed material obtained in step (vi) and 351 liters of water. The bath was heated to 80°C. The cationized dyed material was run in the bath for 10 minutes. The bath was drained thereafter to obtain a washed cationized dyed material.
viii. Neutralization: Machine bath was loaded with the washed cationized dyed material obtained in step (vii) and 351 liters of water. Acetic acid solution (33%) was added to the bath to adjust the bath pH between 5 to 5.5. 0.5 gm /lit of Invatex AC was added to the bath. The cationized dyed materal was run in the bath for 10 minutes while maintaining the pH between 5 to 5.5. The bath was drained after treatment to obtain a neutralized cationized dyed material.
ix. Wash with water: Machine bath was loaded with the neutralized cationized dyed material obtained in step (viii) and 351 liters of water. The cationized dyed material was run in the bath for 10 minutes at 25°C. The bath was drained after treatment to obtain a washed cationized dyed material.
x. Cotton dyeing: Machine bath was loaded with the washed cationized dyed material obtained in step (ix) and 351 liters of water. The auxiliaries inclduing Dep. ACA B-Liq. (1 gm/liter), Albatex AB55 (0.5 gm/liter) and Orgakol TSP (0.5 gm/liter) were added to the bath. The bath was heated to 50°C. The disperse dyes namely Corafix yellow ECO+ (0.40%), Corafix red ECo+ (1.32 %) and Corafix Black GDE (7.83 %) were added to the bath over 20 minutes at 50°C. The cationized dyed material obtained in step (ix) was run in the bath for 20 minutes of the residence time. The first alkali of sodium bicarbonate (5 gm/liter) was added in the bath over 20 minutes followed by addition of second alkali of sodium hydroxide (1.5 gm/liter) over 30 minutes to adjust the pH of the bath between 11 to 11.5. The bath was run for 5 minutes and further it was heated to raise the temperature of the bath from 50°C to 60°C. The material was run in the bath for 40 minutes of the residence time to dye cotton fiber component of the material. A depth of the shade of the dyed material was checked by taking small window cutting. The bath was drained after dyeing to obtain a dyed material.
xi. Wash with water: Machine bath was loaded with the dyed material obtained in step (x) and 351 liters of water. The dyed material was run in the bath for 10 minutes at 25°C. The bath was drained after treatment to obtain a washed dyed material.
xii. Neutralization: Machine bath was loaded with the washed dyed material obtained in step (xi) and 351 liters of water. Acetic acid solution (33%) was added to the bath to adjust the bath pH between 5 to 5.5. 0.5 gm /lit of Invatex AC was added to the bath. The dyed materal was run in the bath for 10 minutes while maintaining pH between 5 to 5.5. The bath was drained after treatment to obtain a neutralized dyed material.
xiii. Treatment with wash off agent: Machine bath was loaded with the neutralized dyed material obtained in step (xii) and 351 liters of water. Diakol ECO (2gm/liter) was added. The bath was heated to 85°C and the material was run in the bath for 20 minutes at maintained temperature. The bath was drained upon the completion of the treatment to obtain a treated dyed material.
xiv. Hot wash: Machine bath was loaded with the treated dyed material obtained in step (xiii) and 351 liters of water. The bath was heated to 80°C. The dyed material was run in the bath for 10 minutes. The bath was drained thereafter to obtain a washed dyed material.
xv. Wash with water: Machine bath was loaded with the washed dyed material obtained in step (xiv) and 351 liters of water.The dyed material was run in the bath for 10 minutes of residence time at 25°C. The bath was drained thereafter to obtain the dyed material.

RESULTS:
• the number of steps : 15;
• the cost of the dyeing is around Rs. 19916/-;
• the total water consumption is around 5564 Liters;
• the total time consumption is around 10 Hour 42 minutes; and
• the effluent generated is around 5170 Liters.
• Depth of the black color: 100% with STD;
• Surface smoothness of the dyed material was scrutinized manually and it was found satisfactorily fine with no mentionable changes;
• Color fastness properties
• The dyed polyester-cotton blend materials "B" prepared according to the example 2 was tested for the color fastness properties i.e. color fastness to wash and color fastness to rubbing by ISO 105-C06: A2S and ISO 105-x12 respectively.
• The color fastness property to wash of dyed fabric sample B was tested and rating of color staining to Cotton/ Nylon/ Polyester/ Acrylic/ Wool for the dyed material B was being rated 4.
• The color fastness properties to both dry and wet rubbing of dyed fabric sample B was tested and color fastness to both dry and wet rubbing for the sample B was being rated 4 and 2 respectively.

Example 3:
Dyeing of polyester-cotton blend according to the invention.
The polyester-cotton blend (80:20) Knit PC Fleece construction having 270-280 gsm (Sample C) was used herein.
a) Pre-treatment (scouring and cationization in a single bath): Machine bath was filled with 650 liters of water. 130 kg of polyester-cotton blend material was loaded in the bath. To this, auxiliaries namely 0.70 gm/liter of Exhosperse HC, 1 gm/liter of Exowet ES, and 0.5 gm /liter of Dep. ACA B-Liq. were added. The bath was heated to temperature of 60°C. The bath was run for 10 minutes. To this bath, 9.75 Kg of sodium hydroxide was added at 60°C over 3 minutes to adjust the bath pH to 11 to 11.5 and the bath was run for 10 minutes. 39 Kg of cationizing agent, 3-chloro-2-hydroxypropyl trimethyl ammonium chloride, (Rishlyte® 9098) was added to the bath at 60°C over 3 minutes and the bath was allowed to run for 10 minutes. The temperature of the bath was increased to 85°C at the rate of 3°C/minute. The bath was run at 85°C for 45 minutes. The bath was cooled to 80°C. The bath was drained to obtain a cationized material.
b) Hot wash: The bath was loaded with the cationized material obtained in step (a) and 351 liters of water. The bath was heated to 80°C over 5 minutes. The material was run in the bath for 10 minutes. The bath was drained after treatment to obtain a washed cationized material.
c) Neutralization: The bath was loaded with the washed cationized material obtained in step (b) and 351 liters of water. Acetic acid solution (33%) was added to the bath to adjust the pH between 5 to 5.5. 1 gm/liter of Invatex AC was added in the bath. The bath was run for 10 minutes while maintaining pH between 5 to 5.5. The bath was drained after treatment to obtain a neutralized cationized material.
d) Single bath dyeing of polyester fiber component and cotton fiber component of the material: The bath was loaded with the neutralized cationized material obtained in step (c) and 351 liters of water. The auxiliaries including Dep. ACA B-Liq. (1 gm/liter), sodium acetate (1 gm/liter), Sunsoft LM7 (1 gm/liter), Levocol CWS (2 gm/liter), acetic acid (1 gm / liter), Albatex AB55 (0.5 gm/liter) and Orgakol TSP (0.5 gm/liter) were added to the bath. The pH of the bath was adjusted and maintained between 5 to 5.5. The bath was heated to 60°C. The disperse dyes namely Coralene brilliant red HP3BS (0.002%) and Coralene black RLS (2.25%); and reactive dyes namely Corafix yellow ECO+ (0.400%), Corafix red ECo+ (1.32 %) and Corafix Black GDE (7.830 %) were added to the bath over 20 minutes. The bath was heated to 90°C at the rate of 3°C/min followed by heating the bath from 90°C to 110°C at the rate of 2.5°C/min further heating the bath from 110°C to 130°C at the rate of 1.5°C/min. The material was run in the bath at 130°C for 40 minutes. The bath was cooled from 130°C to 110°C at the rate of 1.5°C/min followed by cooling the bath from 110°C to 90°C at the rate of 2.5°C/min and further the bath was cooled from 90°C to 60°C at the rate of 3°C/min. Sodium carbonate (6 gm/liter) was added to the bath over 20 minutes. The bath was run for 3 minutes. Sodium hydroxide (1.9 gm/liter) was added over 30 minutes. The pH of the bath was around 10.5. The bath was run for 45 minutes to complete dyeing. The cutting shade of material was matched with standard cutting shade by runing the bath further about 25 minutes. Upon matching of the shade, the bath was drained to obtain a dyed material.
e) Wash with water: The bath was loaded with the dyed material obtained in step (d) and 351 liters of water. The material was run in the bath for 10 minutes at 25°C. The bath was drained after treatment to obtain a washed dyed material.
f) Neutralization: The bath was loaded with the washed dyed material obtained in step (e) and 351 liters of water. Acetic acid solution (33%) was added to the bath to adjust the pH between 5 to 5.5. Invatex AC (1 gm/liter) was added to the bath. The bath was run for 10 minutes while maintaining the pH between 5 to 5.5. The bath was drained after treatment to obtain a neutralized dyed material.
g) Treatment with wash off agent: The bath was loaded with the neutralized dyed material obtained in step (f) and 351 liters of water. Diakol ECO (4 gm/liter) was added to the bath over 3 minutes. The bath was heated to 95°C and the material was run in the bath for 15 minutes at maintained temperature. The bath was drained upon treatment to obtain a treated dyed material.
h) Acid reduction clearing: The bath was loaded with the dyed material obtained in step (g) and 351 liters of water. Acetic acid solution (33%) as neutralizaing agent was added to the bath to adjust the pH between 5 to 5.5. Cyclanon ECO (4 gm/liter) was added to the bath over 3 minutes. The bath was heated to 80°C and the material was run in the bath for 15 minutes at maintained temperature. The bath was drained upon treatment to obtain a treated dyed material.
i) Hot wash: The bath was loaded with the treated dyed material obtained in step (h) and 351 liters of water. The bath was heated to 80°C over 5 minutes. The material was run in the bath for 10 minutes. The bath was drained after treatment to obtain a washed dyed material.
j) Wash with water: The bath was loaded with the washed dyed material obtained in step (i) and 351 liters of water. The material was run in the bath at 25°C for 10 minutes. The bath was drained after treatment to obtain a dyed material.

RESULTS:
• number of steps: 10,
• the cost of the dyeing is around Rs. 17,201/-;
• the total water consumption is around 3809 Liters;
• the total time consumption is around 9 Hours 32 minutes;
• the effluent generated is around 3419 Liters; and
• Glauber's Salt eliminated;
• Depth of the black color: 100.20% with STD, and
• Surface smoothness of the dyed material was scrutinized manually and it was found satisfactorily fine with no mentionable changes.
• Color fastness properties
The dyed polyester-cotton blend materials "C" prepared according to the example 3 was tested for the color fastness properties i.e. color fastness to wash and color fastness to rubbing by ISO 105-C06: A2S and ISO 105-x12 respectively.
• The color fastness property to wash of dyed fabric sample C was tested and rating of color staining to Cotton/ Nylon/ Polyester/ Acrylic/ Wool for the dyed material C was being rated 5.
• The color fastness properties to both dry and wet rubbing of dyed fabric sample C were tested and color fastness to both dry and wet rubbing for the sample C was being rated 5 and 3 respectively.

Example 4:
Dyeing of polyester-cotton blend according to the invention without acid reduction clearing.
The polyester-cotton blend (80:20) Knit PC Fleece construction having 270-280 gsm (Sample D) was used herein.
1. Pre-treatment (scouring and cationization in a single bath): Machine bath was filled with 650 liters of water. 130 kg of polyester-cotton blend material was loaded in the bath. To this, auxiliaries namely 0.70 gm/liter of Exhosperse HC, 1 gm/lit of Exowet ES, and 0.5 gm /liter of Dep. ACA B-Liq. were added. The bath was heated to temperature of 60°C. The bath was run for 10 minutes. To this bath, 9.75 Kg of sodium hydroxide was added at 60°C over 3 minutes to adjust the bath pH to 11 to 11.5 and the bath was run for 10 minutes. 39 Kg. of cationizing agent, 3-chloro-2-hydroxypropyl trimethyl ammonium chloride, (Rishlyte® 9098) was added to the bath at 60°C over 3 minutes and the bath was allowed to run for 10 minutes. The temperature of the bath was increased to 85°C at the rate of 3°C/min. The bath was run at 85°C for 45 minutes. The bath was cooled to 80°C. The bath was drained to obtain a cationized material.
2. Hot wash: The bath was loaded with the cationized material obtained in step (1) and 351 liters of water. The bath was heated to 80°C over 5 minutes. The material was run in the bath for 10 minutes. The bath was drained after treatment to obtain a washed cationized material.
3. Neutralization: The bath was loaded with the washed cationized material obtained in step (2) and 351 liters of water. Acetic acid solution (33%) was added to the bath to adjust the pH between 5 to 5.5. 1 gm/liter of Invatex AC was added in the bath. The bath was run for 10 minutes while maintaining pH between 5 to 5.5. The bath was drained after treatment to obtain a neutralized cationized material.
4. Single bath dyeing of polyester fiber component and cotton fiber component of the material: The bath was loaded with the neutralized cationized material obtained in step (3) and 351 liters of water. The auxiliaries inclduing Dep. ACA B-Liq. (1 gm/liter), sodium acetate (1 gm/liter), Sunsoft LM7 (1 gm/liter), Levocol CWS (2 gm/liter), acetic acid (1 gm / liter), Albatex AB55 (0.5 gm/liter) and Orgakol TSP (0.5 gm/liter) were added to the bath. Bath pH was adjusted and maintained between 5 to 5.5. The bath was heated to 60°C. The disperse dyes namely Coralene brilliant red HP3BS (0.002%) and Coralene black RLS (2.25%); and reactive dyes namely Corafix yellow ECO+ (0.400%), Corafix red ECo+ (1.32 %) and Corafix Black GDE (7.830 %) were added to the bath over 20 minutes. The bath was heated to 90°C at the rate of 3°C/minute followed by heating bath from 90°C to 110°C at the rate of 2.5°C/minute further heating the bath from 110°C to 130°C at the rate of 1.5°C/minute. The material was run in the bath at 130°C for 40 minutes. The bath was cooled from 130°C to 110°C at the rate of 1.5°C/minute followed by cooling the bath from 110°C to 90°C at the rate of 2.5°C/minute and further the bath was cooled from 90°C to 60°C at the rate of 3°C/minute. Sodium carbonate (6 gm/liter) was added to the bath over 20 minutes. The bath was run for 3 minutes. Caustic (1.9 gm/liter) was added over 30 minutes. The pH of the bath was around 10.5. The bath was run for 45 minutes to complete dyeing. The cutting shade of material was matched with standard cutting shade by runing bath further for about 25 minutes. Upon matching of the shade, the bath was drained to obtain a dyed material.
5. Wash with water: The bath was loaded with the dyed material obtained in step (4) and 351 liters of water. The material was run in the bath for 10 minutes at 25°C. The bath was drained after treatment to obtain a washed dyed material.
6. Neutralization: The bath was loaded with the washed dyed material obtained in step (5) and 351 liters of water. Acetic acid solution (33%) was added to the bath to adjust the pH between 5 to 5.5. Invatex AC (1 gm/liter) was added to the bath. The bath was run for 10 minutes while maintaining the pH between 5 to 5.5. The bath was drained after treatment to obtain a neutralized dyed material.
7. Treatment with wash off agent: The bath was loaded with the neutralized dyed material obtained in step (6) and 351 liters of water. Diakol ECO (4 gm/liter) was added to the bath over 3 minutes. The bath was heated to 95°C and the material was run in the bath for 15 minutes at maintained temperature. The bath was drained upon treatment to obtain a treated dyed material.
8. Hot wash: The bath was loaded with the treated dyed material obtained in step (7) and 351 liters of water. The bath was heated to 80°C over 5 minutes. The material was run in the bath for 10 minutes. The bath was drained after treatment to obtain a washed dyed material.
9. Wash with water: The bath was loaded with the washed dyed material obtained in step (8) and 351 liters of water. The material was run in the bath at 25°C for 10 minutes. The bath was drained after treatment to obtain a dyed material.
The dyed sample D is used for the comparative study with respect to color fastness properties.
• Color fastness properties
The dyed polyester-cotton blend materials "D" prepared according to the example 4 was tested for the color fastness properties i.e. color fastness to wash and color fastness to rubbing by ISO 105-C06: A2S and ISO 105-x12 respectively.
• The color fastness property to wash of dyed fabric sample D was tested and rating of color staining to Cotton / Acrylic/ Wool for the dyed material D was being rated 4 and rating of color staining to Nylon/ Polyester for the dyed material D was being rated 3 to 4
• The color fastness properties to both dry and wet rubbing of dyed fabric sample D was tested and color fastness to both dry and wet rubbing for the sample D was being rated 4 and 2 respectively.

According to the results of the above-mentioned examples 1 to 3, it is evident that the current invention reduces the number of steps to 10, 26.9 to 31.5 % of fresh water consumption, 29.1 to 33.8 % of effluent drain, 10.9 to 20.5 % of time consumption, 6.2 to 13.6 % of cost of dyeing and eliminates the use of salt/electrolyte. Importantly, the current invention also improves the color fastness to wash and to both wet rubbing and dry rubbing of the dyed polyester-cotton blend. Thus, the method of dyeing of the polyester-cotton blend material of the invention comprising single bath pre-treatment consisting of scouring and cationization, single bath dyeing polyester fibre component and cotton fibre component of the material simultaneously followed by acidic reduction clearing is cost-effective and eco-friendly.