Claims:WE Claim :

1. A cost-effective and an eco-friendly process of dyeing a material selected from cotton or cotton/lycra blends;
the process comprising:
a) a pre-treatment comprising of scouring and cationization of the material in a single pre-treatment bath by suspending material in water in 1: 5 ratio followed by adding 15 to 60 gm/liter of cationizing agent and about 1/4th alkali on the weight of cationizing agent to adjust pH of the bath in the range of 10 to 14 to obtain a cationized material and a residual pre-treatment bath, and
b) a dyeing of the cationized material in a dye bath to obtain a dyed material;
characterized in that the residual pre-treatment bath of the first and previous cycle of step (a) is recycled in the subsequent cycle of the pre-treatment step (a) till 5th cycle of the pre-treatment step (a) of the dyeing process.

2. The process as claimed in claim 1, wherein the pre-treatment step (a) further comprises bleaching along with scouring and cationization of the material by adding 1 to 8 gm/liter of hydrogen peroxide.

3. The process as claimed in claim 1, wherein the recycling of the residual pre-treatment bath of step (a) of the first and previous cycle in the subsequent cycle of the pre-treatment step (a) of the process of dyeing,
the recycling comprising;
(i) estimating an unused cationizing agent in the residual pre-treatment bath of step (a) of the first and previous cycle of pre-treatment step (a), adding a desired amount of the cationizing agent to reconstitute it to 15 to 60 gm/liter along with addition of about 1/4th alkali on the weight of desired amount cationizing agent added to adjust pH of the residual pre-treatment bath in the range of 10 to 14 in the subsequent cycle of the pre-treatment step (a); and
(ii) recycling the residual pre-treatment bath of step (a) of the first and previous cycle in the subsequent cycle till 5th cycle of the pre-treatment step (a) as per step (i).

4. The process as claimed in claim 3, wherein the estimation step (i) further comprises adding 1 to 8 gm/liter of hydrogen peroxide at the end of scouring and cationization to bleach the material.

5. The process as claimed in claim 3, wherein the estimation of the unused cationizing agent in the residual pre-treatment bath of step (a) is estimated in step (i) as follows:
1) the cationization of the fresh material in the residual pretreatment baths of step (a) in step (i) by suspending the fresh material in the residual bath followed by adding water to make ratio of material to water in 1: 5 subsequently adding alkali to adjust pH of the bath in the range of 10 to 14 to obtain a cationized material and a residual pre-treatment bath;
2) dyeing the cationized material in a dye bath to obtain a dyed material;
3) estimating the depth of colour of dyed material and comparing it with standard dyed material of step (b);
4) estimating the amount of unused cationizing agent in the residual bath of step (a) in step (1) in view of the results obtained in step (3); and
5) optimizing unused cationizing agent in the residual bath of step (a) in step (1) by repeating steps (1) to (4) thrice with the residual bath of first or previous cycle of pre-treatment step (a).

6. The process as claimed in claim 5, wherein the step (2) further comprises bleaching along with scouring and cationization of the material by adding 1 to 8 gm/liter of hydrogen peroxide.

7. The process as claimed in claim 5, wherein the estimation of the unused cationizing agent in the residual pre-treatment bath of step (a) in step (i) is carried out by Kjeldhal method.

8. The process as claimed in claims6 and 7, wherein the residual pre-treatment bath of step (a) is comprising 45 to 55% of the unused cationizing agent.

9. The process as claimed in claims6 and 7, whereinthe residual pre-treatment bath of the first and previous cycle of pre-treatment step (a) is loaded with 45 to 55 % of the cationizing agent, preferably 50%, to reconstitute it to 15 to 60 gm/liter of cationizing agent in step (i) till 5th cycle of the pre-treatment of step (a).

10. The process as claimed in claims 6 and 7, wherein the residual pre-treatment bath of step (a) is further loaded with the material, water to reconstitute the material to water ratio 1:5, 1/4thof alkali on the weight of 45 to 55 % of cationizing agent added to adjust the pH of the bath in the range of 10 to 14 and optionally 1 to 8 gm/liter of hydrogen peroxide in the subsequent cycle till 5th cycle of the pre-treatment of step (a) in step (i).

Dated this 1st day of November 2019

(Dr. Shilpa Gharve)
Agent of the Applicant
(Regn.No.IN/PA 890)
, Description:FIELD OF INVENTION:
The present invention relates in general to a process of dyeing of cellulosic material including cotton or its blends with lycra.

In particular, the present invention relates to a cost-effective and eco-friendly process of dyeing of cellulosic material including cotton or its blends with lycra.

BACKGROUND OF THE INVENTION:
Cotton fabrics are commonly dyed with reactive dyes, which are very popular because of their brilliant range of hues and excellent fastness properties. All the reactive dyeing systems require huge amounts of electrolyte such as sodium chloride or sodium sulphate to exhaust dyeing. It also requires huge amount of alkali to fix the dye. These electrolytes are neither exhausted nor destroyed and hence, remain in the dye bath after dyeing. Further, only 60 to 65% of dye utilization is achievable even with the use of salt in the normal dyeing systems. Reactive dyeing thus pollutes the environment due to highly colored dye bath discharge as well as the discharge of high electrolyte concentration. The high electrolyte concentration in the effluents cause adverse effects on the aquatic organisms as the electrolyte triggers the evolution of hydrogen sulfide gas and thus disturbs the balance in biochemistry of the aquatic organisms. It also leads to deposition of aminosulphate complex in the concrete pipes.

To resolve this aforesaid problem, the industry implemented the surface modification of cellulosic fabric by cationization. A number of processes have been reported from the early 1930s to improve the substantivity of anionic dyes for cellulose by introducing cationic sites in the fibre. The cationizing agents reported for cellulosic fibers are glycidyltrimethylammonium chloride, N,N-dimethylazetidiniumchloride, N-methylolacrylamide, chloro propionyl chloride, polymer PL, polyepichlorohydrin acrylamides, nicotinyl thioglycollate, 3-chloro-2-hydroxypropyl trimethyl ammonium chloride (CHPTMAC) and polyamino chlorohydrin quaternary ammonium compound (Cibafix WFF). Some of them have yielded encouraging results.

The reactive dyeing of the cellulosic / cotton fibers is usually carried out in 4 steps namely, scouring, bleaching, cationization and dyeing. Particularly, the scouring, bleaching, and cationization of the cellulosic / cotton fibers is carried out in alkaline condition with the addition of alkali, particularly sodium hydroxide.

Scouring improves water absorbency and makes the cotton fabric to look clean and soft. However, some cotton fabric have natural color and therefore, the fabric may not meet the requirement of whiteness. To improve the whiteness, the fabric is subjecting to bleaching upon treatment with hydrogen peroxide in alkaline condition either at high temperature or at long residence time. These leads to high energy consumption and may cause damage to the cotton fibers of the fabric. The fabric is further subjected to cationization in the alkaline condition to modify the surface and to increase affinity towards dye.

CN108486929 (A) titled "Dyeing method of cotton socks" discloses sequential subjection of socks to pretreatment scouring and bleaching, enzyme treatment, and cationization treatment. This dyeing method has the advantage that the fiber and other fiber fabrics can be better dyed; the color with uniform darkness and uniform color luster can be obtained; a certain color fastness degree is reached.

Since, the scouring, bleaching and cationization of cotton fibers are all under alkaline conditions, attempts were made to combine these steps in the existing art to reduce alkali dosage, treatment time, water and consumed energy thus overall cost.

The article titled "New development for combined bio-scouring and bleaching of cotton based fabrics" by Hebeish, A., etc al Carbohydr. Polym. 2009, 78, 961-972; reported combining the scouring and bleaching treatment.

The article titled "combinative scouring, bleaching, and cationization pretreatment of Greige Knitted Cotton Fabrics for facilely achieving salt free reactive dyeing" by Wei, Ma, et. al. Molecules 2017, 22, 2235; reported combining the scouring, bleaching and cationization treatment. This article also reports that the residue liquid of scouring and bleaching has large amount of alkali and this residue cannot be reused.

There are also attempts made to recycle waste water of dye bath in the existing art. The article titled "Treatment and reuse of reactive dyeing effluents" Journal of Membrane Science 269 (2006) 15–34 discloses the dye bath treatment to recover water and minerals and recycling of the same. It consists of four steps to recover the water and mineral salts and disposing off the stream consisting of spent dyes. The steps consisting of 1) cartridge filtration to remove textile fibers, 2) acidification to recover brine and reuse in dyeing, 3) nano filtration to concentrate the hydrolyzed dyes and reverse osmosis to concentrate the salts to reuse in dyeing. This treatment concern only very dilute dye baths. This treatment is generally not implemented in heavily polluted dye bath.

CN106365350 (A) titled "Black printing wastewater pollutant extraction and resource utilization method" discloses the black printing wastewater pollutant extraction by coagulation, gas floatation or precipitation method. The sludge particles so obtained were recycled.

The dyeing of one kilogram of cotton with reactive dyes demands from 70 to150 Liters water, 0.6 to 0.8 kg NaCl and anywhere from 30 to 60 gm dyestuff. More than 80,000 tonnes of reactive dyes are produced and consumed each year, making it impossible to estimate the total pollution caused by their use in conventional salt dyeing.

In the dyeing using cationization, the various treatment baths including scouring, bleaching, cationization and dye bath and various washes are drained out. This causes pollution and increases 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 combines scouring, bleaching and cationization in a single bath to reduce the water consumption and reduce the generation of effluent.

However, there is still a need to reduce the water consumption, effluent generation, costing, energy consumption, treatment time, consumption of cationizing agent, consumption of alkali and lastly but significantly reduce pollution by developing reactive dyeing process of recycling the bath.

OBJECTS OF THE INVENTION:
The main object of the invention is to provide a cost-effective and an eco-friendly process of dyeing of a material selected from cellulosic material including cotton or its blends with lycra; wherein the material is pre-treated to scouring, bleaching and cationization in a single pre-treatment bath subsequently dyeing the cationized material; a residual pre-treatment bath is recycled till 5th cycle.

Another object of the invention is to provide a cost-effective and eco-friendly process of dyeing of the material selected from cellulosic material including cotton or its blends with lycra; wherein the residual pre-treatment bath is recycled thereby reducing water consumption and making the process cost-effective.

Yet another object of the invention is to provide a cost-effective and eco-friendly process of dyeing of the material selected from cellulosic material including cotton or its blends with lycra; wherein the residual pre-treatment bath is recycled thereby reducing effluent generation and making the process eco-friendly.

Still another object of the invention is to provide a cost-effective and eco-friendly process of dyeing of the material selected from cellulosic material including cotton or its blends with lycra; wherein the residual pre-treatment bath is recycled along with unused cationizing agent and alkali thereby reducing wastage of cationizing agent and alkali and making the process cost-effective as well as eco-friendly.

SUMMARY OF THE INVENTION:
In the presently claimed invention, it is surprisingly found that the residual pre-treatment bath can be recycled till 5th cycle of the pre-treatment step of the process of dyeing according to the invention. The recycling of residual pre-treatment bath was standardized by estimating unused cationizing agent in it. The experiments were carried out to optimize loading of a fresh cationizing agent in the residual pre-treatment bath to reconstitute the cationizing agent in the subsequent cycle of the pre-treatment step of the process of dyeing of the invention. After experimentals, it was optimized to load 45 to 55% of cationizing agent, preferably 50% to reconstitute the agent in the residual pre-treatment bath to use in the subsequent cycle of the pre-treatment of the dyeing of the material. Since, the residual pre-treatment bath was recycled till 5th cycle, the process of the presently claimed invention reduced consumption of water by 15 to 25%, preferably 21%; cationizing agent by 30 to 50%, preferably 40%; alkali by 30 to 50%, preferably 40%, and effluent generation by 20 to 30%, preferably 26%. The cost of the pre-treatment step of the presently claimed invention is reduced by 30 to 50%, preferably 40%, to its original cost and thereby reducing the overall cost of the process of dyeing. Thus, the process of the presently claimed invention also reduces water consumption and effluent generation thereby reducing pollution, which is main advantage besides economic benefits.

The presently claimed invention is directed to a cost-effective and an eco-friendly process of dyeing the material selected from cellulosic material including cotton or its blends with lycra;
the process comprising:
a) a pre-treatment comprising of scouring and cationization of the material in a single pre-treatment bath by suspending material in water in 1: 5 ratio followed by adding 15 to 60 gm/liter of cationizing agent and about 1/4th alkali on the weight of cationizing agent to adjust pH of the bath in the range of10 to 14 to obtain a cationized material and a residual pre-treatment bath, and
b) a dyeing of the cationized material in a dye bath to obtain a dyed material; and
characterized in that the residual pre-treatment bath of the first and previous cycle of step (a) is recycled in the subsequent cycle of the pre-treatment step (a) till 5th cycle of the pre-treatment step (a) of the dyeing process.

Typically, the pre-treatment step (a) further comprises bleaching along with scouring and cationization of the material by adding 1 to 8 gm/liter of hydrogen peroxide.

Particularly, the recycling of the residual pre-treatment bath of step (a) of the first and previous cycle in the subsequent cycle of the pre-treatment step (a) of the process of dyeing of the present invention,
the recycling comprising;
(i) estimating an unused cationizing agent in the residual pre-treatment bath of step (a) of the first and previous cycle of pre-treatment step (a), adding a desired amount of the cationizing agent to reconstitute it to 15 to 60 gm/liter along with addition of about 1/4th alkali on the weight of desired amount cationizing agent added to adjust pH of the residual pre-treatment bath in the range of 10 to 14 in the subsequent cycle of the pre-treatment step (a); and
(ii) recycling the residual pre-treatment bath of step (a) of the first and previous cycle in the subsequent cycle till 5th cycle of the pre-treatment step (a) as per step (i).

Typically, the estimation step (i) further comprises adding 1 to 8 gm/liter of hydrogen peroxide at the end of scouring and cationization to bleach the material.

Typically, the estimation of the unused cationizing agent in the residual pre-treatment bath of step (a) is estimated in step (i) as follows:
1) the cationization of the fresh material in the residual pretreatment baths of step (a) in step (i) by suspending the material in the residual bath followed by adding water to make ratio of material to water as 1: 5 subsequently adding alkali to adjust pH of the bath in the range of 10 to 14 to obtain a cationized material and a residual pre-treatment bath;
2) dyeing the cationized material in a dye bath to obtain a dyed material;
3) estimating the depth of colour of dyed material and comparing it with standard dyed material of step (b);
4) estimating the amount of unused cationizing agent in the residual bath of step (a) in step (1) in view of the results obtained in step (3); and
5) optimizing the amount of unused cationizing agent in the residual bath of step (a) in step (1) by repeating steps (1) to (4) thrice with the residual bath of first or previous cycle of pre-treatment step (a).

In the estimation steps (3) to (4), the unused cationizing agent remained in the residual bath of step (a) in the step (1) is directly proportional to dept of colour of dyed material obtained in step (2). Thus, if the depth of the colour of the dyed material is 50 % to that of standard, then the unused cationizing agent remained in the residual bath of step (a) is 50 % to that of original amount of cationizing agent in step (a). The standard used for the comparison in step (3) is the dyed material obtained in first cycle of the pre-treatment of step (a) followed by dyeing of step (b).

Typically, the step (2) further comprises bleaching along with scouring and cationization of the material by adding 1 to 8 gm/liter of hydrogen peroxide.

Typically, the estimation of the unused cationizing agent in the residual pre-treatment bath of step (a) is also carried out by Kjeldhal method in step (i).

Typically, according to the estimation of the unused cationizing agent of steps (1) to (5), the residual pre-treatment bath of the first and previous cycle of pre-treatment step (a) is comprising 45 to 55 % of the unused cationizing agent, preferably 50%.

Typically, the residual pre-treatment bath of the first and previous cycle of pre-treatment step (a) is loaded with 45 to 55 % of the cationizing agent, preferably 50%,to reconstitute it to 15 to 60 gm/liter of cationizing agent in step (i) till 5th cycle of the pre-treatment of step (a).

Typically, the residual pre-treatment bath of step (a) is further loaded with the material, water to reconstitute the material to water ratio of 1:5,1/4th of alkali on the weight of 45 to 55 % of cationizing agent added to adjust the pH of the bath in the range of 10 to 14 and optionally adding 1 to 8 gm/liter of hydrogen peroxide in the subsequent cycle till 5th cycle of the pre-treatment of step (a) in step (i).

Due to recycling of the residual pre-treatment bath of step (a) of the first and previous cycle in the subsequent cycle till 5th cycle of the pre-treatment step (a) as per step (i), the present invention reduced the consumption of water, alkali, and cationizing agent by 15 to 25%, preferably 21%; 30 to 50%, preferably 40%; and 30 to 50%, preferably 40% respectively as compared with conventional process.

Due to recycling of the residual pre-treatment bath of step (a) of the first and previous cycle in the subsequent cycle till 5th cycle of the pre-treatment step (a) as per step (i), the present invention reduced the volume of effluent of the pre-treatment step (a) by 20 to 30 %, preferably 26% as compared with conventional process.

Due to recycling of the residual pre-treatment bath of step (a) of the first and previous cycle in the subsequent cycle till 5th cycle of the pre-treatment step (a) as per step (i), the present invention reduced the cost of the pre-treatment bath of step (a) by 30 to 50 %, preferably 40 % till 5th cycle as compared with conventional process. Thereby, the present invention, also reduced the overall cost of dyeing of the material as compared with conventional process.

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 the fibers of cotton or its blends with lycra (i.e. cotton/lycra blends).

As used herein, the terms "cellulosic material" refers to fabric or fiber or yarn of a cellulose including cotton. The fabric or yarn is either woven or knitted or felted fabric / yarn made up of the cellulose including the cotton fibers.

As used herein, the terms " cotton/lycra blends " refers to fabric or fiber or yarn of cotton and lycra 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 lycra 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 among us. The textile industry 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 cellulosic material including cotton material or cotton/lycra blends. Particularly, the material is fiber, fabric or yarn is either cotton or cotton/lycra blends, etc. The fabric is having density of = 50 gsm and =1000 gsm.

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 sodium hydroxide (2 to 3 gm/liter and pH in the range of 10 to 14) in presence of surfactants or wetting agents for about 30 to 60 minutes. Upon the completion of scouring process, it is washed subsequently with plentiful amount of water. Scouring helps to improve 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 are 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 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 pH of the bath in the range of 10.5 to 10.8. Upon completion of the bleaching process, it is first neutralized and then 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.

Neutralization is carried out by adding acid selected from acetic acid, citric acid, and/or maleic acid with core neutralizing agent including Invatex AC.

Particularly, the neutralization is carried out by adding around 2 gm/liter of acetic acid and 1 gm/liter Invatex AC, (Huntsmann).

The treated material after scouring or bleaching is subjected to cationization by treating it with the cationizing agent in alkaline condition, particularly at pH of 10 to 14 using alkali, particularly sodium hydroxide either at high temperatures, particularly at 80 to 90°C or at a long dwell time. Upon the completion of the cationization, the cotton material is subjected to hot wash at 80°C. Subsequently, the cationized fabrics/ fibers are neutralized and washed with plenty of water.

The cationized material are subjected to a reactive dyeing or a disperse dyeing in a dye bath at 50 to 80°C or 90 to 130°C respectively and subsequently treated with alkali to adjust the pH in the range of 10.50 to 12.50 at the constant temperature. The dyed fabric is hot washed and cold washed with plenty of water.

Usually the scouring, bleaching and cationization pre-treatments of the material are carried out in separate baths or in a single bath and subsequently the material is dyed. When the scouring, bleaching and cationization treatments are carried out in single pre-treatment bath, combined scouring and cationization is carried out initially in the pre-treatment bath followed by bleaching at the end of the treatment.

When these pre-treatments are carried out in the separate baths conventionally (i.e. scouring and bleaching combined in a single bath and cationization in separate bath) for 300 kg of the material selected from cellulosic material including cotton or cotton/lycra blends; then
the total water consumption is approximately 5550 liters,
the total alkali consumption is approximately 25.5 kg,
the time of combined scouring, bleaching followed by cationization is approximately 245 minutes,
the effluent generation is approximately 4860 liters,
the unused cationizing agent remains in the cationization bath is approximately 50%, and
the costing of the pre-treatment is approximately Rs. 26004/.

When these pre-treatments are carried out in the single bath (i.e. scouring, bleaching and cationization combined in a single bath) for 300 kg of the material selected from cellulosic material including cotton or cotton/lycra blends; then
the total water consumption is approximately 3120 liters,
the total alkali consumption is approximately 22.5 kg,
the total time of combined scouring, bleaching and cationization is approximately 186 minutes,
the effluent generation is approximately 2430 liters,
the unused cationizing agent remains in the cationization bath is approximately50%, and
the costing of the pre-treatment is approximately Rs. 23830.75/-.
Thus the cost of the pre-treatment is reduced upon carrying out these pre-treatments in the single bath to 8 % and thereby reducing the total costing of process of dyeing of cellulosic material.

Thus, combining the scouring, bleaching and cationization in the single pretreatment bath reduced consumption of water, effluent generation, time consumption and the costing of the pre-treatment to approximately 43.7 %, approximately 50%, 23% and 8 % respectively, thereby reducing the overall costing of dyeing process.

However, still there is a large amount of unused alkali and unused cationizing agent in the residue pre-treatment bath which is never exploited to reuse or recycle. The waste water treatment of the residue bath is also difficult because of the alkaline residue.

Thus, the present invention is focused to reduce the use of cationizing agent, water and effluent generation as well as reusability of pre-treatment bath comprising unused cationizing agent and unused alkali along with other ingredients without affecting color fastness, hue, brilliance, etc and surface morphology of the fabric.

In the presently claimed invention, conditions of and quantities of the raw materials used in the pre-treatment and the dyeing are optimized after examining the material's properties including whiteness, water absorbance, diffusion time, capillary effect, surface morphology, and thermal properties, as well as dye fixation, color yield, and colorfastness properties.

The presently claimed invention is directed to a cost-effective and eco-friendly process of dyeing a material selected from cellulosic material including cotton or cotton/lycra blends.

In the presently claimed invention, the process consisting of :
a. the pre-treatment comprising the scouring and the cationization of the material in the single pre-treatment bath by suspending the material in the water in the ratio of 1:5 followed by adding 15 to 60 gm/liter of cationizing agent and about 1/4th alkali on the weight of cationizing agent to adjust pH of the bath in the range of 10 to 14 to obtain the cationized material and the residual pre-treatment bath; and
b. the dyeing of the cationized material in the dye bath to obtain the dyed material; characterized in that the residual pre-treatment bath of the first and previous cycle of step (a) is recycled in the subsequent cycle of the pre-treatment step (a) till 5th cycle of the pre-treatment step (a) of the dyeing process.

In step (a), the pre-treatment bath comprising 0.5 to 1 gm/liter of wetting agent, and 10 to 80 gm/liter of cationizing agent. To this, 1/4th alkali on the weight of cationizing agent is added to maintain pH of the bath in the range of 10 to 14. 300 kg of the material or its blends with lycra having =50 gsm to = 1000 gsm is added in the pre-treatment bath. Scouring and cationization is carried out at temperature in the range of 80 to 90°C for 30 to 60 minutes.

The pre-treatment step (a) further comprises bleaching along with scouring and cationization of the material.

Typically, the pre-treatment step (a) further comprises bleaching along with scouring and cationization of the material by adding 1 to 8 gm/liter of hydrogen peroxide.

We have observed that hydrogen peroxide has no stability initially, and hence hydrogen peroxide is added in the pre-treatment bath after carrying out combined scouring and cationization processes (i.e. approximately 45 minutes) to carry out the bleaching.

In step (a), the pre-treatment bath comprises 0.5 to 1gm/liter of wetting agent and 10 to 80 gm/liter of cationizing agent. To this, alkali is added to maintain pH of the bath in the range of 10 to 14. 300 kg of material having =50 gsm is added in the pre-treatment bath. Scouring and cationization is carried out at temperature in the range of 80 to 90°C for 20 to 45 minutes. Upon completion of the scouring and the cationization, 1 to 8 gm/liter of hydrogen peroxide is added in the pre-treatment bath and the bleaching is carried out at temperature in the range of 90 to 100°C, preferably95°C for 30 to 45 minutes.

The bleaching of the material is carried out in presence of stabilizer.

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. The wetting agent used in the present invention is EXSO WET ES.

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. The stabilizer used in the present invention is Chel DTPA-41 Liq. (Pentasodium pentetate based).

The cationizing agent is selected from 3-chloro-2-hydroxypropyl trimethyl ammonium chloride (CHPTMAC). Preferably, the cationizing agent used in the present invention is available under trade name Rishlyte® 9098.

In step (b), dyeing of the cationized material is carried out by treating the cationized material with 9.745% of reactive dye at temperature in the range of 50 to 80°C for 20 to 45 minutes followed by treatment with alkali (i.e. dye fixation) at pH in the range of 10.5 to 12.5 and at temperature in the range of 40 to 80°C for 30 to 45 minutes followed by treatment with soaping agent and washing with plenty of water till wash bath become clear.

The dyes used are reactive dyes selected from ME and HE class of reactive dyes and disperse dyes selected from anthraquinonoid and azo based disperse dyes.

In the presently claimed invention, the recycling of the residual pre-treatment bath of step (a) of the first and previous cycle in the subsequent cycle of the pre-treatment step (a) till 5th cycle of the pre-treatment step (a) of the dyeing process is carried out as follows:
i. The unused cationizing agent in the residual pre-treatment bath of step (a) of the first and previous cycle of pre-treatment step (a) is estimated. As per the estimation, the desired amount of the cationizing agent is added to reconstitute it to 15 to 60 gm/liter in the residual pre-treatment bath.1/4th alkali on the weight of desired amount cationizing agent is added to the residual bath to adjust pH in the range of 10 to 14 in the subsequent cycle of the pre-treatment step (a); and
ii. The residual pre-treatment bath of step (a) of the first and previous cycle is recycled in the subsequent cycle till 5th cycle of the pre-treatment step (a) as per step (i).

Typically, the estimation step (i) further comprises adding 1 to 8 gm/liter of hydrogen peroxide at the end of scouring and cationization to bleach the material.

The unused cationizing agent in the residual pre-treatment bath of step (a) is estimated in step (i), which is as follows:
1) the cationization of a fresh material in the residual pretreatment baths of step (a) in step (i) is carried out by suspending the fresh material in the residual bath followed by adding water to make ratio of material to water as 1: 5 subsequently adding alkali to adjust pH of the bath in the range of 10 to 14 to obtain a cationized material and a residual pre-treatment bath;
2) the cationized material is dyed in a dye bath to obtain a dyed material;
3) the depth of colour of dyed material is estimated and compared with standard dyed material of step (b);
4) estimating the amount of unused cationizing agent in the residual bath of step (a) in step (1) in view of the results obtained in step (3); and
5) optimizing the unused cationizing agent in the residual bath of step (a) by repeating steps (1) to (4) thrice with the residual bath of first or previous cycle of pre-treatment step (a).

The step (1) further comprises bleaching along with scouring and cationization of the material by adding 1 to 8 gm/liter of hydrogen peroxide.

According to this method of estimation comprising step s (4), the depth of colour of dyed material compared with standard dyed material in step (3) is found to be 50 % to its original depth and thus, unused cationizing agent in the residual bath in step (1) is 50 % of the original cationizing agent added in step (a). Thus, 50 % of fresh cationizing agent need to be added in the residual bath in step (i) comprising 50 % unused cationizing agent. The estimation was repeated thrice with three different residual bath of first or previous cycle of the pre-treatment residual bath to estimate the unused cationizing agent in it and addition of fresh cationizing agent to subsequent cycle of the pre-treatment step (a) and optimizing the same.

The unused cationizing agent in the residual pre-treatment bath of step (a) is also estimated by Kjeldhal method in step (i).

The unused cationizing agent, 3-chloro-2-hydroxypropyl trimethyl ammonium chloride (CHPTMAC) in the pre-treatment bath is estimated by Kjeldhal method where ammonical nitrogen group is determined by titrimetric method.

5 ml of the sample of the residual pre-treatment bath is selected for analysis. Ammonia in the sample is titrated against standard 0.02N sulfuric acid until indicator turns pale lavender against a blank.

Indicator used is prepared as follows:
200 mg of methyl red indicator is dissolved in 100 ml of 95 % ethyl or isopropyl alcohol. 100 mg of methylene blue is dissolved in 50 ml of 95 % ethyl or isopropyl alcohol. These two are combined to form indicator.
The ammonical nitrogen is calculated as follows:
(A – B) X 280
Ammonical nitrogen, mg/liter= --------------------
V

A = volume in ml of sulfuric acid used for sample
B = volume in ml of sulfuric acid used for blank, and
V = volume in ml of sample taken for test.

According to Kjeldhal method, the residual bath of first or previous cycle of the pre-treatment step (a) also confirmed that it comprises around 45 to 55 % unused cationizing agent, preferably 50 % to its original amount in first cycle of the pre-treatment step (a).

According to the above-mentioned method, it was found that the residual pre-treatment bath of the first and previous cycle of the pre-treatment step (a) was comprising approx. 45 to 55 % of the unused cationizing agent, preferably 50%. To reconstitute concentration of the cationizing agent in the subsequent recycled pre-treatment bath of step (i), 45 to 55 % of fresh cationizing agent, preferably 50% was added till 5th cycle.

1/4th of alkali namely caustic soda was added in the residual pre-treatment bath of step (a) in step (i) on the weight of freshly added cationizing agent in the subsequent cycle to activate the cationizing agent till 5th cycle. Apart from cationizing agent and alkali, 2 to 8 gm/liter of hydrogen peroxide and the material to be treated is added in the residual pre-treatment bath of step (a) in the subsequent cycle in step (i) till 5thcycle.Water is also added in step (i) of recycling to reconstitute ratio of the material to water at 1: 5.

The residual pre-treatment bath of the first and previous cycle is recycled in the subsequent steps of (a) process for dyeing the material selected from cellulosic material including cotton or cotton/lycra blends still 5th cycle of pre-treatment.

Thus, the present claimed invention of process of dyeing of 300 kg the material selected from cellulosic material including cotton or cotton/lycra blends by carrying out the treatment of scouring, cationization and optionally bleaching in the single pre-treatment bath and recycling the residual pre-treatment bath of the first and previous cycle in the subsequent cycle till 5thcycle, then
the water consumption is approximately 3120 liters for first cycle and 2310 liters per each 2nd to 5th cycle i.e. average 2472 liters/cycle for 1st to 5th cycle,
the alkali consumption is approximately 22.50 kg for first cycle and 11.25 kg per each 2nd to 5th cycle i.e. average 13.5 kg/cycle for 1st to 5th cycle,
the cationizing agent consumption is approximately 90 kg for first cycle and 45 kg per each 2nd to 5th cycle i.e. average 54 kg/cycle for 1st to 5th cycle,
the effluent generation of step (a) is approximately 1620 liters for 1st to 4th cycle and 2430 liters for 5th cycle i.e. average 1782 liters/cycle for 1st to 5th cycle,
the costing of the pre-treatment is approximately Rs. 23832/- for first cycle and Rs. 16023/- per each 2nd to 4th cycle i.e. average Rs. 17610/- for 1st to 5th cycle, and
thereby the total costing of process of dyeing of the material including pre-treatment and dyeing is also reduced.

Thus, present invention reduced the followings:
i. the water consumption approximately by 15 to 25%,
ii. alkali consumption approximately by 35 to 45%,
iii. cationizing agent consumption approximately by 35 to 45%,
iv. effluent generation approximately by 20 to 30%, and
v. costing of the pre-treatment approximately by 25 to 40%.

Thus, the presently claimed invention makes it cost-effective and eco-friendly. The presently claimed invention also reduces effluent generation as the residual pre-treatment baths is recycled till 5th cycle.

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 cotton (without cationization and with Glauber Salt)
a) Pre-treatment (scouring and bleaching)
1500 liters of water was filled in the tank. To this, 1500 gm of wetting agent (EXSO WET ES), 1500 gm of lubricating agent (DEPSOLUBE ACL-B LIQ), 750 gm of stabilizer and seqest (DIAKOL ECO) and 3kg of caustic were added to adjust the pH in the range of 10.5 to 11 and 300 kg of cotton fabric of about 180 gsm was loaded. The bath in the tank was heated to temperature of 75°C.
To this tank, 500 gm of hydrogen peroxide was added at the constant temperature of 75°C and the bath was run for 2 minutes. The temperature was increased to 95°C in 8 minutes. The fabric was bleached at the temperature of 95°C by running the bath for another 30 minutes. The bath was allowed to cool to 80°C and the bath was drained.
To the tank, 1500 liters of water was added and the temperature of the bath was increased to 85°C. The fabric was swirled in the bath for 10 minutes (i.e. hot washed). The bath was cooled to 80°C . The bath was drained.
To the tank, 1500 liters of water was added and the temperature of the bath was raised to 50°C. To this, approximately 3kg of acetic acid (33% solution) and 750 gm of core neutral (Invatex AC) were added. The fabric was swirled in the bath at 50°C for 10 minutes. The pH of bath was checked and maintained in the range of 5 to 5.5.
To this bath,375 gm of peroxide killer (Arrow CAT PL-Conc) was added and swirled for 10 minutes. The bath was drained. The treated fabric was then subjected to dyeing.
b) Dyeing with reactive dye and Glauber Salt
1500 liters of water was filled in the tank to form a dye bath. To this, 1500 gm of lubricating agent (DEPSOLUBE ACL -B LIQ), 750 gm of leveling agent (Orgokol TSP),450 gm of dispersing agent (Levocol CWS) and 600 gm of pH buffer (EXSO Acid AB55) were added. The bath was heated to 50°C and the temperature was maintained for 2 minutes. To this, reactive dye namely, 472.5 gm of C.YELLOW Eco plus, 330 gm of C.RED Eco Plus and 4.07 kg C. Black GDE were added with 20 minutes dosing time to achieve black shade. To this, 112.5kg of Glauber Salt was added in 12 minutes. The addition 112.5kg of globular salt was repeated. The fabric was allowed to dye by swirling in the bath for 25 minutes.9kg of sodium carbonate and 2850 gm of sodium hydroxide in aqueous solution were added to adjust the pH of the bath in the range of 10.5 to 12.The temperature of the bath was increased to 60°C and maintained for 45 minutes. The shade of black colour was checked by spectrophotometric analysis and the depth was matched with conventional standard sample. The dyeing was continued till depth of the dyed material matched with the standard. The dye bath was drained.
The fabric was subjected to cold wash twice by swirling the dyed fabric in the bath of 1500 liters of water at temperature of 50°C for 10 minutes each time. The bath was drained after each wash.
The fabric was immersed in 1500 liters of water in a bath and it was heated to 50°C.3kg of neutralizing agent (33 % acetic acid) was charged to the bath with stirring to adjust the pH in the range of 5.5 to 6.5. The fabric was swirled for 10 minutes. The bath was drained.
The bath having fabric was filled with 1500 liters of water. To this bath,1 % soap (Dakocal ECO) was added and the temperature was raised to 95°C within short period of time. The fabric was swirled for 10 minutes at 95°C. The bath was cooled to 80°C and it was drained.
The bath having fabric was again filled with1500 liters of water and temperature was raised to 80°C. The hot wash was carried out by swirling the fabric in this bath at 80°C for 10 minutes. The bath was drained.
The fabric was placed in the bath having 1500 liters of water and temperature was raised to 50°C. The cold wash was carried out by swirling the fabric in this bath at 50°C for 10 minutes. The bath was drained.
The fabric was subjected to dye-fixing by placing the fabric in bath containing 1500 liters of water and temperature was raised to 50°C. To this, 1.5 % of Dye-fixing agent (Albafix WFF), 1500 gm of acetic acid and 75gm of core neutral (Invatex AC) were added. The bath was run for 10 minutes. The bath was drained and the dyed fabric was dried.
Time: approx.7 hours 48 minutes,
Water consumption:10,910 liters,
Effluent drained: 10,220 liters
Caustic soda used: 3 kg (In pretreatment)
Glauber Salt used: 97.5 kg,
Cost of the dyeing process: Rs. 29250
Depth of the black colour : 101.20% with STD

Example 2:
Process of dyeing of cotton (pretreatment including scouring, bleaching and cationization in a separate bath)
a) Pre-treatment Separate bath scouring, bleaching and cationization (Cotton)
1500 liters of water was filled in the tank. To this, 1500 gm of wetting agent (EXSO WET ES), 1500 gm of lubricating agent (DEPSOLUBE ACL-B LIQ), 750 gm of stabilizer and seqest (DIAKOL ECO) and 3 kg of caustic were added to adjust the pH in the range of 10.5 to 11 and 300 kg of cotton fabric of about 180 gsm was loaded. The bath in the tank was heated to temperature of 75°C.
To this tank, 500 gm of hydrogen peroxide was added at the constant temperature of 75°C and the bath was run for 2 minutes. The temperature was increased to 95°C in 8 minutes. The fabric was bleached at the temperature of 95°C by running the bath for another 30 minutes. The bath was allowed to cool to 80°C and the bath was drained.
The bath was filled with 1500 liters of water. To this, 1500 gm of wetting agent (EXSO WET ES), 750 gm of lubricating agent (DEPSOLUBE ACL -B LIQ), 750 gm of chelating agent (EXOSPERSE H/C) were added. The bath was heated to temperature of 60°C. 300 kg of cotton fabric loaded in the bath at the constant temperature of 60°C in15 minutes. To this bath, 22.5kg of caustic soda was dissolved and added at 60°C in 3 minutes and run for another 3 minutes. 90 kg of cationizing agent (Rishlyte® 9098) was added to the bath at 60°C in 10 minutes. The temperature of the bath was increased to 85°Cwithin 8 minutes. Cationization was carried out at 85°C for 45 minutes by swirling the fabric in the bath. The bath was cooled to 78°C in 5 minutes. The bath was drained.
The bath having fabric was filled with 1500 liters of water. The fabric was subjected to hot wash by running in the bath for 10 minutes at 80°C. After completion of hot wash, the bath was drained.
The fabric was immersed in 1500 liters of water in a bath and it was heated to 50°C. To the bath, 3kg of neutralizing agent (acetic acid) and 750 gm of core neutral (Invatex AC) were charged to adjust the pH in the range of 5 to 5.5. The bath was run for 10 minutes. The bath was drained. The treated fabric was then subjected to dyeing.
b) Dyeing
500 liters of water was filled in the bath. The bath was heated to 50°C. To this, 500 gm of lubricating agent (DEPSOLUBE ACL -B LIQ), 500 gm of dispersing agent (Levocol CWS) and 200 gm of pH buffer (EXSO Acid AB55) were added. The pre-treated fabric was immersed in the bath and the bath was maintained at 50°C for 5 minutes. To this, reactive dye namely 472.5 gm of C. YELLOW Eco plus, 330 gm of C.RED Eco Plus and 4.07 kg C. Black GDE were added to achieve black shade. Dye was added over period of 20 minutes. The bath was run for 25 minutes. The pH of the bath was found to be in the range of 5.5 to 6. 9kg of sodium carbonate was added in the bath for 20 minutes. The bath was run for 6 minutes. 2850 gm of sodium hydroxide was added in the bath for 20 minutes. The bath was run for 6 minutes. The pH of the bath was found to be in the range of 10.5 to 12. The temperature of the bath was increased to 60°C for 10 minutes. The bath was run by maintaining temperature at 60°C for 55 minutes. The shade of black of the dyed fabric was checked by spectrophotometric analysis and the depth was matched with standard black coloured fabric. The dyeing process was continued till shade of the sample was found to matched with standard. The dye bath was drained.
The fabric was cold washed with 1500 liters of water by swirling at 50°C for 10 minutes. The bath was drained.
The fabric was immersed in 1500 liters of water in a bath and it was heated to 50°C. To the bath, 3kg of neutralizing agent (acetic acid) was charged to adjust the pH in the range of 5.5 to 6.5. The bath was run for 10 minutes and it was drained.
The tank having fabric was filled with 1500 liters of water. To the bath, 1 % soap (Dakocal ECO) was added and temperature of the bath was raised to 95°C in 8 minutes. The fabric was swirled for 10 minutes at 95°C. The bath was cooled to 80°C and the same was drained.
The fabric was placed in the bath having 1500 liters of water and temperature was raised to 80°C. The hot wash was carried out by swirling the fabric in hot bath at 80°C for 10 minutes. The bath was drained.
The fabric was placed in the bath having 1500 liters of water and temperature was raised to 50°C. The cold wash was carried out by swirling the fabric in the bath at 50°C for 10 minutes. The bath was drained.
The bath having fabric was again filled with 1500 liters of water and the bath was run for another 5 minutes and fabric was unloaded from same bath.
Time: approx. 9 hours 11 minutes.
Water consumption: 11720 liters.
Effluent drained: 11030 liters.
Caustic soda used: 25.50 kg.
Cationizing agent used: 90 kg.
Cost of the pre-treatment process: Rs.26004/-.
Depth of the black colour: 102.50 as compared with STD.

Example 3:
Process of dyeing of cotton (pretreatment including scouring, bleaching and cationization in a single bath)
a) Pre-treatment (scouring, bleaching and cationization in a single bath)
Machine bath was filled with 1500 liters of water. To this, 1500 gm of wetting agent (EXSO WET ES), 750 gm of lubricating agent (DEPSOLUBE ACL -B LIQ), 750 gm of chelating agent (EXOSPERSE H/C) were added. The bath was heated to temperature of 60°C. 300 kg of cotton fabric of about 180 gsm loaded in the bath at the constant temperature of 60°C in15 minutes.
To this bath, 22.5 Kg of caustic soda was dissolved and added at 60°C in 3 min and run for another 3 minutes. 90 Kg of cationizing agent (Rishlyte® 9098) was added to the bath at 60°C in 10 minutes. The temperature of the bath was increased to 85°Cwithin 8 minutes. The cationization was carried out at 85°C for 45 minutes by swirling the fabric in the bath. The bath was cooled to 78°C in 5 minutes. 1500 gm of hydrogen peroxide was added at the constant temperature of 78°C and the fabric was kept swirling for 3 minutes. The temperature was increased to 95°Cwithin 8 minutes. The fabric was bleached at the temperature of 95°C by swirling it for 30 minutes. The bath was allowed to cool to 80°C and this bath was transferred to stock tank for recycling purpose.
The bath having fabric was filled with 1500 liters of water. The fabric was subjected to hot wash by running in the bath for 10 minutes at 80°C. After completion of hot wash, the bath was drained.
The fabric was immersed in 1500 liters of water in a bath and it was heated to 50°C. To the bath, 3 kg of neutralizing agent (acetic acid) and 750 gm of core neutral (Invatex AC) were charged to adjust the pH in the range of 5 to 5.5. The bath was run for 10 minutes. The bath was drained. The treated fabric was then subjected to dyeing.
b) Dyeing
500 liters of water was filled in the bath. The bath was heated to 50°C. To this, 500 gm of lubricating agent (DEPSOLUBE ACL -B LIQ), 500 gm of dispersing agent (Levocol CWS) and 200 gm of pH buffer (EXSO Acid AB55) were added. The pre-treated fabric was immersed in the bath and the bath was maintained at 50°C for 5 minutes. To this, reactive dye namely 472.5 gm of C.YELLOW Eco plus, 330 gm of C.RED Eco Plus and 4.07 Kg C. Black GDE were added to achieve black shade. Dye was added over period of 20 minutes. The bath was run for 25 minutes. The pH of the bath was found to be in the range of 5.5 to 6. 9 kg of sodium carbonate was added in the bath for 20 minutes. The bath was run for 6 minutes. 2850 gm of sodium hydroxide was added in the bath for 20 minutes. The bath was run for 6 minutes. The pH of the bath was found to be in the range of 10.5 to 12. The temperature of the bath was increased to 60°C for 10 minutes. The bath was run by maintaining temperature at 60°C for 55 minutes. The shade of black of the dyed fabric was checked by spectrophotometric analysis and the depth was matched with standard swatch of fabric.
The fabric was cold washed with 1500 liters of water by swirling at 50°C for 10 minutes. The bath was drained.
The fabric was immersed in 1500 liters of water in a bath and it was heated to 50°C. To the bath,3kg of neutralizing agent (acetic acid) was charged to adjust the pH in the range of 5.5 to 6.5. The bath was run for 10 minutes and it was drained.
The tank having fabric was filled with 1500 liters of water. To the bath,1 % soap (Dakocal ECO) was added and temperature of the bath was raised to 95°C in 8 minutes. The fabric was swirled for 10 minutes at 95°C. The bath was cooled to 80°C and the same was drained.
The fabric was placed in the bath having 1500 liters of water and temperature was raised to 80°C. The hot wash was carried out by swirling the fabric in hot bath at 80°C for 10 minutes. The bath was drained.
The fabric was placed in the bath having 1500 liters of water and temperature was raised to 50°C. The cold wash was carried out by swirling the fabric in the bath at 50°C for 10 minutes. The bath was drained.
The bath having fabric was again filled with 1500 liters of water and the bath was run for another 5 minutes and fabric was unloaded from same bath.
Time: approx. 8 hour 14 minutes.
Water consumption: 9290 liter.
Effluent drained: 8600 liter.
Caustic soda used: 22.50 kg.
Cationizing agent used: 90 kg.
Amount residual pre-treatment bath comprising cationized agent: approx. 810 liters comprising 24.30 kg of active cationizing agent.
Cost of the pre-treatment process: Rs. 23830.75/-
Depth of the black colour: 100.60 as compared with STD

Example 4:
Process of dyeing of cotton /lycra blend (96:4) (pretreatment including scouring, bleaching and cationization in a single bath)
a) Pre-treatment (scouring, bleaching and cationization in a single bath)
Machine bath was filled with 1500 liters of water. To this, 1500 gm of wetting agent (EXSO WET ES), 750 gm of lubricating agent (DEPSOLUBE ACL -B LIQ), 750 gm of chelating agent (EXOSPERSE H/C) were added. The bath was heated to temperature of 60°C. 300 kg of cotton /lycra blend (96:4) fabric of about 180 gsm loaded in the bath at the constant temperature of 60°C in15 minutes.
To this bath, 22.5 kg of caustic soda was dissolved and added at 60°C in 3 min and run for another 3 minutes. 90 kg of cationizing agent (Rishlyte® 9098) was added to the bath at 60°C in 10 minutes. The temperature of the bath was increased to 85°Cwithin 8 minutes. The cationization was carried out at 85°C for 45 minutes by swirling the fabric in the bath. The bath was cooled to 78°C in 5 minutes. 1500 gm of hydrogen peroxide was added at the constant temperature of 78°C and the fabric was kept swirling for 3 minutes. The temperature was increased to 95°C within 8 minutes. The fabric was bleached at the temperature of 95°C by swirling it for 30 minutes. The bath was allowed to cool to 80°C and this bath was transferred to stock tank for recycling purpose.
The bath having fabric was filled with 1500 liters of water. The fabric was subjected to hot wash by running in the bath for 10 minutes at 80°C. After completion of hot wash, the bath was drained.
The fabric was immersed in 1500 liters of water in a bath and it was heated to 50°C. To the bath, 3 kg of neutralizing agent (acetic acid) and 750 gm of core neutral (Invatex AC) were charged to adjust the pH in the range of 5 to 5.5. The bath was run for 10 minutes. The bath was drained. The treated fabric was then subjected to dyeing.
b) Dyeing
500 liters of water was filled in the bath. The bath was heated to 50°C. To this, 500 gm of lubricating agent (DEPSOLUBE ACL -B LIQ), 500 gm of dispersing agent (Levocol CWS) and 200 gm of pH buffer (EXSO Acid AB55) were added. The pre-treated fabric was immersed in the bath and the bath was maintained at 50°C for 5 minutes. To this, reactive dye namely 472.5 gm of C.YELLOW Eco plus, 330 gm of C.RED Eco Plus and 4.07 kg C. Black GDE were added to achieve black shade. Dye was added over period of 20 minutes. The bath was run for 25 minutes. The pH of the bath was found to be in the range of 5.5 to 6. 9 kg of sodium carbonate was added in the bath for 20 minutes. The bath was run for 6 minutes. 2850 gm of sodium hydroxide was added in the bath for 20 minutes. The bath was run for 6 minutes. The pH of the bath was found to be in the range of 10.5 to 12. The temperature of the bath was increased to 60°C for 10 minutes. The bath was run by maintaining temperature at 60°C for 55 minutes. The shade of black of the dyed fabric was checked by spectrophotometric analysis and the depth was matched with standard swatch of fabric.
The fabric was cold washed with 1500 liters of water by swirling at 50°C for 10 minutes. The bath was drained.
The fabric was immersed in 1500 liters of water in a bath and it was heated to 50°C. To the bath, 3 kg of neutralizing agent (acetic acid) was charged to adjust the pH in the range of 5.5 to 6.5. The bath was run for 10 minutes and it was drained.
The tank having fabric was filled with 1500 liters of water. To the bath,1 % soap (Dakocal ECO) was added and temperature of the bath was raised to 95°C in 8 minutes. The fabric was swirled for 10 minutes at 95°C. The bath was cooled to 80°C and the same was drained.
The fabric was placed in the bath having 1500 liters of water and temperature was raised to 80°C. The hot wash was carried out by swirling the fabric in hot bath at 80°C for 10 minutes. The bath was drained.
The fabric was placed in the bath having 1500 liters of water and temperature was raised to 50°C. The cold wash was carried out by swirling the fabric in the bath at 50°C for 10 minutes. The bath was drained.
The bath having fabric was again filled with 1500 liters of water and the bath was run for another 5 minutes and fabric was unloaded from same bath.
Time: approx. 8 hour 14 minutes.
Water consumption: 9290 liter.
Effluent drained: 8600 liter.
Caustic soda used: 22.50 kg.
Cationizing agent used: 90 kg.
Amount residual pre-treatment bath comprising cationized agent: approx. 810 liters comprising 24.30 kg of active cationizing agent.
Cost of the pre-treatment process: Rs. 23830.75/-.
Depth of the black colour: 99.80 as compared with STD.

Estimation of cationizing agent in the residual pre-treatment bath of examples3 and4
The residual pre-treatment bath of 810 liters of step (a) of examples 3 and 4 was analysed for the concentration of cationizing agent.

The residual pre-treatment bath was filtered to remove fibres and other impurities like oil, fats and waxes. It was used as the pre-treatment bath and 300 kg of cotton fabric or cotton /lycra blend (96:4) was subjected to pre-treatment and dyeing as per the examples 3 and 4 respectively excluding the addition of cationizing agent but addition of water and alkali to adjust the fabric to water ratio at 1: 5 and pH in the range of 10 to 12 respectively. The depth of the dyed fabric was checked by spectrophotometric analysis. The dyeing process was continued till shade of the sample was found to be constant. The depth of of the dyed fabric was matched with standard. It was found 50 % lighter depth than that of standard. Thus, it was concluded that the unused cationizing agent remaining in the residual pre-treatment bath of 810 liters of step (a) of examples 3 and 4 was 50 %.

The estimation of unused cationizing agent was repeated with bath of residual pre-treatment bath of 810 liters of step (a) of examples 3 and 4 of another two baths and found that the unused cationizing agent remaining in the residual pre-treatment bath was consistently 50 %.
The estimation of unused cationizing agent was repeated with bath of residual pre-treatment bath of 810 litersof step (a) of examples 3 and 4 of three batches were also carried out by Kjeldhal method. 50 % of unused cationizing agent was found in the residual bath.

Recycling of the residual pre-treatment bath of examples 3 and 4 till 5 cycle.

The residual pre-treatment bath was filtered to remove fibres and other impurities like oil, fats and waxes of the first cycle i.e. examples 3 and 4. It was found to have 50% of initial concentration of cationizing agent. The pH of the residual bath was found to be in the range of 10 to 14. The residual pre-treatment bath of step (a) was recycled in step (a) by following the exact same process of examples 3 and 4 step (a) except the quantity of water, cationizing agent and caustic soda used. The quantity of cationizing agent and caustic soda was added to restore their concentration at required step (a) till 5th cycle as per the estimation method and pH estimation of the residual bath. The residual pre-treatment bath was disposed off after 5th cycle.
The quantity of water, cationizing agent and caustic soda used to restore their concentration in the step (a) in the number of cycles for examples 3 and 4 are given below in the Table 1.
Table 1

No. of cycles Water
Liter Cationizing agent
Kg Caustic soda
Kg
Recycling of the residual pre-treatment bath of Example 3
1 3120 90 22.5
2 2310 45 11.25
3 2310 45 11.25
4 2310 45 11.25
5 2310 45 11.25
Recycling of the residual pre-treatment bath of Example 4
1 3120 90 22.5
2 2310 45 11.25
3 2310 45 11.25
4 2310 45 11.25
5 2310 45 11.25

Economic and Ecological significance

The residual pre-treatment bath of step (a) was recycled in step (a) by following the exact same process of examples 3 and 4 step (a), the estimation of quantity of fresh water consumption, total effluent drained, fresh cationizing agent used, fresh caustic soda used, cost of pre-treatment and overall cost of dyeing by recycling the residual bath was carried out. The results of the same are given in Table 2.

No. of cycles Fresh water consumption
(Litre) Reduction in water consumption
(%) Total effluent generation / drained
(Litre) Reduction in effluent
(%) Fresh Caustic soda consumption
(Kg) Reduction in Caustic soda consumption
(%) Fresh cationizing agent consumption
(Kg) Reduction in
cationizing agent consumption
(%) Cost of pre-treatment/kg
(INR) Cost reduction
(%)
Recycling of the residual pre-treatment bath of example Example 3
1 3120 0 1620 33.33 22.50 0 90 0 23830.75 -
2 2310 25.96 1620 33.33 11.25 50 45 50 16023.25 32.76
3 2310 25.96 1620 33.33 11.25 50 45 50 16023.25 32.76
4 2310 25.96 1620 33.33 11.25 50 45 50 16023.25 32.76
5 2310 25.96 2430 0 11.25 50 45 50 16144.75 32.25
Avg. 2472 20.76 1782 26.66 13.50 40 54 50 17609.05 26.10
Recycling of the residual pre-treatment bath of example Example 4
1 3120 0 1620 33.33 22.50 0 90 0 23830.75 0
2 2310 25.96 1620 33.33 11.25 50 45 50 16023.25 32.76
3 2310 25.96 1620 33.33 11.25 50 45 50 16023.25 32.76
4 2310 25.96 1620 33.33 11.25 50 45 50 16023.25 32.76
5 2310 25.96 2430 0 11.25 50 45 50 16144.75 32.25
Avg. 2472 20.76 1782 26.66 13.50 40 54 50 17609.05 26.10
Table 2
According to the above-mentioned results of Table 2 and the data produced against each examples, it is evident that the current invention reduces 15 to 25 % of fresh water consumption, 20 to 30% of effluent drain, 45 to 55% of fresh caustic soda consumption, 30 to 50% of cost of the pre-treatment and 30 to 50% of cost of dyeing. Thus, the process of dyeing of the material selected from cotton or cotton/lycra blends of the invention which recycles the residual pre-treatment bath till 5th cycle, thereby making the invention cost-effective and eco-friendly.