Dyeing of Polyester Cotton Blended Fabric in Single Bath

Last Updated on 25/03/2021

Scope of Dyeing Polyester Cotton (PC) Blended Fabric in Single Bath Process for Water Saving, Energy Saving and Time Saving

Ripon Kumar Prasad & Md. Rashed Ahamad
Department of Textile Engineering
Dhaka University of Engineering & Technology (DUET)
Gazipur -1700, Bangladesh

ABSTRACT
Dyeing of fabric blends such as Polyester/Cotton (P/C) is presently done with two chemically different classes of dyes namely disperse dye for polyester and reactive dye for cotton, in two bath process. Experimental work was carried out on finding the possibility of dyeing the P/C blends in one bath process without drain the liquor after polyester part dyeing. All the existing chemical and conventional temperature range were applied in this study. The result indicates that, the using of one bath method in the polyester cotton dyeing can slightly change the fastness properties than the conventional method. The one bath dyeing method showed level dyeing having good fastness properties and offers the option of cost effective and eco-friendly dyeing process.

Keywords: PC blend fabric, single bath dyeing, shade matching, color fastness, water saving, energy saving, time saving, cost effective.

1. INTRODUCTION
In textile industry polyester / cotton (P/C) blends have dominant market share having share of 58.45% in worldwide – market. These blends are famous due to their aesthetic value and user-friendly performance. Limitations of both fibers are balanced adequately by blending these two fibers making perfect blend. However, the P/C blends possess some challenges to dyer as polyester shows a hydrophobic character while cotton shows a hydrophilic character making it inevitable to dye them with chemically different class of dyes.

The conventional method of exhaust dyeing for P/C blends is to dye each component separately under its optimum conditions, i.e. in a two-bath process. To address the issue of productivity and raising environmental concerns, several attempts have been made in the past to shorten this to one-bath processes.

Various other combinations of dyes like disperse/direct and disperse/vat can be used in single bath dyeing but, the matching of shade is quite difficult. Reactive dyes have some significant advantages over other dyes applicable to cotton: viz., color value, reproducibility of color, and fastness properties are usually better, and the dyeing is easier to wash-off.

The one-bath dyeing process uses a separated high-pH and low temperature reactive fixation step after the high temperature, low pH disperses dyeing to avoid a high rate of hydrolysis of both disperse and reactive dyes under high temperature, or high pH dyeing environment. This process is shorter as compared to two-bath dyeing process.

This one bath method has the advantages over the conventional dyeing processes on reducing the dyeing cycle as well as energy consumption and water consumption.

1.1 Objectives of the Project and Thesis

• To innovate in the cotton polyester dyeing method in one bath over the two bath method.
• To investigate the CMC pass/fail value for one bath dyeing method sample.
• To investigate the different fastness properties such as fastness to wash, fastness to rubbing, fastness to perspiration and compared it to the conventional two bath dyeing method.
• To determine water consumption, energy consumption and time consumption and compared it to the two bath dyeing method.

1.2 Research Question

• Is it possible to dyeing polyester cotton fabric in single bath process?
• Does the remaining disperse dyes create any problem on cotton fabric after polyester part dyeing.
• Does the enzyme create any problem during dyeing?
• Is it possible to match the shade of single bath process comparing to the double bath process?
• Is it possible to get good fastness properties in single bath method comparing to the double bath method?

2. LITERATURE REVIEW

2.1 Previous Work
In the previous work cotton polyester single bath dyeing process has been done by using physical mixture of reactive and disperse dyes. Some requirements for both disperse and reactive dyes are needed when physical mixture is used. But in this research work dyeing is completed in single bath without drain of water. Here no special requirements for the dye and chemicals are needed. All the existing chemicals can be used which are used in traditional two bath method. [8]

2.2 Literature Review

2.2.1 Cotton Fibre
A cotton fibre consists of a cuticle, primary wall, secondary wall and a lumen. Cotton fibre has natural twist along the entire length of the fibre called convolutions. The convolutions and kidney shape cross section of the cotton fibre enable it to make only random contact with the skin. This type of contact is more compatible with the human skin physiology and therefore more comfortable. Long fibres have about 300 convolutions per inch and short fibres have 200 or less.

Cotton fibre is a cellulosic fibre, which is actually the purest natural form of cellulose. Cotton fibre is about 94% of cellulose. The rest of the materials are protein, peptic substances, ash, fat and wax, organic acid, sugar etc which are primarily located in the primary wall and some in the lumen. Cotton contains carbon, hydrogen and oxygen with reactive hydroxyl groups. Cotton may have as many as 10,000 glucose monomers per molecule. The combination of two beta glucose units formed a cellubiose unit and 5000 cellubiose units form cellulose molecule or cotton polymer that is, its degree of polymerization is about 5000.

It is very long, linear polymer about 5000 nm in length and 0.8 nm thick. The most important chemical group on the cotton polymer are hydroxyl groups (-OH) groups and methyl groups (-CH₂OH). Cotton is a crystalline fibre. Its polymer system is about 65-70% crystalline and about 30-35% amorphous. Different properties of cotton fibre which make it useful in many situations or purpose such as capacity to absorb moisture, high strength, high absorbency, good conductivity of heat, luster appearance. Other properties are-

• The diameter of cotton fibre is 16-20 micron.
• The tenacity of cotton fibre is 3-4.9 gm/denier at dry condition and 3.6-6.0 gm/denier at wet condition.
• The color of the cotton fibre is generally white, grey and cream.
• The elongation of cotton fibre is good. The breaking elongation is about 8-10%.
• The moisture regain percentage of cotton is 8.5%.
• Cotton fibres are resistant to alkalis but it weakened and destroyed by the acids.
• Cotton fibre is relatively easy to dye and print. [6]

2.2.2 Cotton Fabric
Cotton fabric which is made from cotton fibre and used as comfortable, durable and suitable in any weather. Cotton fabric is used as a wide range of wearing apparels, blouses, T-shirts, polo shirts, dresses, children’s wear, sportswear, swimwear, suits, jackets, skirts, trousers, sweaters and hosiery. Moreover, cotton fabric is immensely used as home fashions such as curtains, draperies, bedspreads, sheets, towels, table cloths, table mats, napkins etc. [3]

2.2.3 Polyester Fibre
Polyester is a man-made polymer material. Polyester was first introduced as a group of polymers in W.H. Characters laboratory, who led by the DuPont company in America during the 1920s and 1930s to develop synthetic fibre. A group of British scientists took up Carothers, work in 1939. In 1941 they created the first usable polyester fibre called terylene. Another polyester fibre is produced which called Dacron in 1952. In 1959 another polyester fibre called Kodel was developed by Eastman Chemical Products. Polyester has hydrocarbon back bones characterized by the presence of carboxylate ester groups distributed either regularly along the main polymer chain. The fibre forming polyester may be obtained from dicarboxylic acids with diols, hydroxyl acid. Commercially, aromatic polyester is applied using ethylene glycol (EG) and dimethyl terephthalete (DMT), or ethylene glycol and terepthalic acid (TPA) to produce polyethylene terepthalete (PET).

Before 1970, polyester was exclusively produced on a commercial scale from ethylene glycol and dimethyl terephthalate. After 1970, Mobil Co. and Amoco Co. Polyester fibre is a manufactured fibre in which the fibre forming substance is a long chain synthetic polymer composed at least 85% by weight of an ester of a substituted aromatic carboxylic acid, including but not restricted to substituted terephthalic units, p(-R-O-CO-C6H4-CO-O-)X and para substituted hydroxi-benzoate units, p(-R-O-CO-C6H4-O-)X. The para substituted hydroxy benzoate units in PET are ethylene groups (CH2-CH2). The most widely used polyester fibre is made from the linear polymer poly (ethylene terephthalate), and this polyester class is generally referred to simply as PET.

Polyethylene terephthalate (PET) is a condensation polymer and is industrially produced by either terephthalic acid or dimethyl terephthalate with ethylene glycol. Other polyester fibres of interest to the nonwovens field include:

• Terephthalic Acid (TPA), produced directly from p-xylene with bromide –controlled oxidation.
• Dimethyl Terephthalate (DMT), made in the early stages by esterification of terephthalic acid. However, a different process involving two oxidation and esterification stages now accounts for most DMT.
• Ethylene Glycol (EG) initially generated as an intermediate product by oxidation of ethylene. Further ethylene glycol is obtained by reaction of ethylene oxide with water. [2]

2.2.4 Characteristics of Polyester Fibre
Polyester fibres are extremely strong. Polyester is very durable resistant to most chemicals, stretching and shrinking, wrinkle resistant, mildew and abrasion resistant. Polyester is hydrophobic in nature. It can be used for insulation by manufacturing hollow fibres. The physical and chemical properties of polyester fibres are:

1. Polyester fibres have good moisture transport and dry quickly.
2. They can be used where lightness and fineness are primary requirements.
3. Fabrics that composed by 100% polyester or blends with an appropriately high proportion are very crease resistant and retain shape even when affected by moisture.
4. Polyester fibres are very well suited to blend with different naturals fibres.
5. High tenacity ensures above average wear qualities.
6. The average fineness of polyester is about 0.5-1.5 denier.
7. The tenacity of polyester at dry condition is 3.5-7.0 and in wet condition 3.5-7.0.
8. The moisture regain percentage is very minimum that is 0.4.
9. The percentage of elongation at break in dry condition is 15-45 and wet condition is 15-45.
10. The specific gravity is 1.36-1.41.
11. The melting point is about 260-270.
12. Resistance to weathering well.
13. Polyester is damaged by concentrated alkali.
14. Resistance to most of the chemicals. [4]

2.2.5 Polyester Fabric
Polyester is a very popular synthetic fabric. All polyester fabric is made primarily from petroleum. The polymerization or chain reaction involving ethylene creates polyester, which was patented in 1941, is widely available and is relatively inexpensive. Polyester fabric that is made from petroleum bi-products. It is very durable and easy to care for and is usually manufactured in a variety of weights and textures. It is used for to take clothing, industrial fabric and home furnishings. Knit fabrics such as jersey are what T-shirt and sweatshirts are made by polyester. They are able to stretch and are available in medium and light weights. The nice thing about knit fabrics with polyester is that they can move easily, which makes them great for used in sports uniforms. Another plus is that it won’t shrink as much as garment made out of 100% natural fibres, which lengthens the life of the fabric. There are all kinds of woven fabrics that can be made with polyester but some of the most common ones are denim, shirting, twill and basket weave fabrics. These are fabrics that do not stretch, unless pulled on the bias (Diagonally across the weave). Twills and denim can be especially sturdy when the fibre content including polyester. In fact, jeans are often made with a poly cotton fabric in order to give a fabric more sheen or even a metallic look, while making a strong and more flexible. Shirts with label boasting “wrinkle free” are more likely to contain polyester because it keeps the fabrics light without creasing or wrinkling as easily as 100 percent cotton shirts. Basket weave fabric has a texture that is popular for table cloths and tear resistant, close structured, flame retardant and UV protected. Polyester fabrics are used in banners, pennants, small, table and glossy flags, complex images, table cloths, 3D effects and also in umbrella. [5]

2.2.6 Polyester Cotton Blended Fabric
Polyester cotton is a blended fabric made of both the artificial polyester and the natural cotton. The blend is perfect for clothing as it brings both benefits of the two fabrics together. The fabric thus remains lightness and coolness of the cotton and polyester gives the strength and durability. This blend is usually comfortable by combining the natural effects of cotton for softness and moisture adsorption with the no iron crispness of polyester. The most common polyester cotton blend is found 65% polyester and 35% cotton, 80% cotton and 20% polyester etc.

Individually polyester and cotton has some drawbacks. Cotton fibres are expensive, wrinkles easily, they shrink, burn easily and not resilient. They have a tendency to absorb water. Polyester fibres are hard, low elasticity, non-absorbent and tendency to pilling. When cotton and polyester fibres are blended and made polyester cotton blended fabric, it removes this problem and gives many improve feature to the blended fabric.

Polyester cotton blended fabric only shrinks slightly in comparing to a garments or fabric that is made of 100% cotton. Moreover, the combination of polyester cotton blended fabrics is less costly. [7]

2.2.7 Dyeing of Polyester Cotton Blended Fabric
An advantage of incorporating polyester in cotton from dyer’s point of view is that it can withstand relatively severe preparation necessary for cotton before dyeing. On polyester cotton dyeing, the degree of staining is less, prolonged boiling favors migration of disperse dyes to polyester without severe attack on cellulose and the stain can be removed by reduction cleaning. Reactive dyes give negligible staining on polyester.

Several possible batch wise dyeing methods for polyester cotton are based on the use of disperse dyes and various classes of dye for cotton fibres, depending on the requirements of the hue, depth and fastness of the shades and cost consideration. B class disperse dyes may be used for low cost one bath process based on carrier dyeing with direct or sulphur dyes for the cotton fibres. Disperse and direct dyes can be applied in a cheap, simple, one bath process but fastness is inadequate. Medium to full depths can be obtained with disperse and vat dyes in one bath two stage sequence, but instability of vat dyes at high temperature may create a problem

In economical dyeing process may also be used with disperse and reactive dyes for bright and fast shade and optimum fastness. Many of the hot brand reactive dyes are sufficiently stable to withstand the conditions of high temperature dyeing and they can be dyeing one bath two step dyeing sequence. Carrier method is not recommended as the carriers have restraining action on the exhaustion and fixation of the reactive dyes. The cold brand reactive dyes may be applied with disperses dyes separately by pad batch method before dyeing polyester component. [1]

2.2.8 Reactive Dyes
The molecular structures of reactive dyes resemble those of acid and simple direct cotton dyes, but with an added reactive group. Typical structures include the azo (a), anthraquinone (b), triphenodioxazine. The key structural features of a reactive dye are the chromophoric system, the sulphonate groups for water solubility, the reactive group, and the bridging group that attaches the reactive group either directly to the chromophore or to some other part of the dye molecule. The chromophoric system consist of azo, quinoid carbonyl, nitroso, nitro-group, carbonyl, vinyl group (-N=N-, C=O, -NO, -NO₂, >C=O, -C=C-) etc unsaturated group. Each of these structural features can influence the dyeing and fastness properties. Most commercial ranges of reactive dyes have a complete gamut of colors, many of which are particularly bright. Reactive dyes often have quite simple structures that can be synthesised with a minimum of colored isomers and bi products that tend to dull the shade of the more complex polyazo direct dyes. Some colors are difficult to obtain with simple chromophores. Dark blue and navy reactive dyes are often rather dull copper complexes of azo dyes and the production of bright green reactive dyes remains a problem.

A wide range of possible fibre-reactive groups has been examined and evaluated by the dyestuff manufacturers. The final choices for commercial dyes are limited by a number of constraints. The reactive group must exhibit adequate reactivity towards cotton, but be of lower reactivity towards water that can deactivate it by hydrolysis. The hydrolysis of the dye’s reactive group is similar to its reaction with cellulose but involves a hydroxyl ion in water rather than a cellulosate ion in the fibre. In addition, the dye–fibre bond, once formed, should have adequate stability to withstand repeated washing. Other factors involved are the ease of manufacture, the dye stability during storage and the cost of the final reactive dye. [1]

2.2.9 Disperse Dye
The majority of disperse dyes are low molecular weight, non-ionic mono-azo and anthraquinone derivatives. Polar substituent is usually present in the dye molecule so that the dye has the slight solubility in water required for dyeing. Hydroxyethylamino groups (NH-CH₂-CH₂-OH) are typical of such substituent. The interaction of such polar groups with the water, by dipole interactions and hydrogen bonds, is crucial for water solubility. Dipole forces and hydrogen bonds, as well as dispersion forces, also bind the dye molecules to polar groups in the fibres.

There are many thousands of azo disperse dye structures because of the numerous substitution patterns possible in the diverse diazonium ion and coupling components. Colors that are less typical of simple azo compounds, such as greenish-yellow and blue are also possible using more specialized components. These may have heterocyclic units or cyano substituent. There is also a limited number of other chromophores providing disperse dyes with particular properties. Anthraquinone disperse dyes are usually 1-hydroxy or 1-amino derivatives. These have bright colors ranging from red through to blue. Simple anthraquinone dyes have low molar absorptivities compared to azo compounds and therefore give dyeings of lower color yield. Apart from a few bright pinks and blues, anthraquinone disperse dyes are gradually being replaced. In their manufacture, the production of the required intermediate chemicals, and of the dyes themselves, often involves complex reactions under pressure. The reaction equipment is more sophisticated than that used for the simpler azo coupling reaction. In addition, anthraquinone-1-sulphonic acids are key intermediates and the sulphonation reactions for their preparation use a mercuric ion catalyst. The environmental threat of mercury in the chemical plant effluent has led to increasingly stringent regulations for its containment and therefore increased production costs.

There are no true green or black disperse dyes. Dyes with both red and blue light absorption bands for greens, or with several overlapping absorption bands for blacks, are difficult to prepare. A major constraint for disperse dye structures is the relatively low molecular weight that the dye must have to be slightly water-soluble and to be able penetrate into hydrophobic synthetic fibres. A combination of blue and yellow dyes gives green dyeing. Blacks require an after treatment of the dyeing involving diazotization of the absorbed dye containing a free primary amino group followed by reaction with a coupling component. Black disperse dyes may also be mixtures of dull orange, rubine and navy dyes. Many disperse dyes are mixtures generated by the reactions used in their synthesis. Techniques such as thin layer chromatography are useful for establishing the number of components.[1]

3. MATERIALS AND METHOD

3.1 Diagram of Methodology
In order to dyeing of polyester cotton blended fabric in the one bath dyeing process and comparing the result with the conventional process same fabric were dyed both one bath and two bath method. During dyeing both samples are taken and the properties of the both samples were measured.

3.2 Materials

3.2.1 Knitted Fabric Parameters

• Fabric type: Single jersey.
• Grey GSM: 175
• Finished GSM: 160 5
• Yarn count: 28 Ne
• Cam arrangement: All are knit cams.

3.2.2 Dyes and Chemical

Table 1: Specification of dyes and chemical

3.2.3 Machineries

Table 2: Specification of machineries

3.3 Calculation for Amount of Dyes and Chemicals

3.3.1 Laboratory Process
During the lab dip, little amount of dyes and other chemicals were required. For this reason, stock solution is prepared. Stock solution ensured accurate amount of dyes and chemicals for a process which can be measured by following formula.

3.3.2 Bulk Production

Amount of Chemicals = Total liquor X Recipe rate

Amount of Dyes = Fabric weight X Shade%

3.4 Recipe

3.4.1 Recipe for Scouring and Bleaching

Table 3: Recipe for souring and bleaching

3.4.2 Recipe for Hot Wash

Table 4: Recipe for hot wash

3.4.3 Recipe for Neutralization

Table 5: Recipe for neutralization

3.4.4 Recipe for Enzyme Treatment

Table 6: Recipe for enzyme treatment

3.4.5 Recipe for Polyester Dyeing

Table 7: Recipe for polyester part dyeing

3.4.6 Recipe for Cotton Dyeing

Table 8: Recipe for cotton part dyeing

3.4.7 Recipe for Soaping

Table 9: Recipe for soaping

3.4.8 Recipe for Softening

Table 10: Recipe for softening

3.5 Laboratory Trial Process

3.5.1 Pretreatment Working Procedure

Table 11: working procedure for pretreatment (lab)

3.5.2  Pretreatment Process Curve

3.5.3  Process Flow of Two Bath Dyeing Method

Table 12: Process flow for two bath method (lab)

3.5.4  Dyeing Curve of Two Bath Method

3.5.5  Process Flow of One Bath Dyeing Method

Table 13: Process flow of one bath method (lab)

3.5.6  Dyeing Curve of One Bath Method

3.5.7 Process Flow of After Treatment

Table 14: Process flow of after treatment (lab)

3.5.8  Curve of After Treatment

3.6 Bulk Production

3.6.1  Pretreatment Working Procedure

Table 15: working procedure for pretreatment (bulk)

3.6.2 Pretreatment Process Curve

3.6.3  Process Flow of Two Bath Dyeing Method

Table 16: Process flow for two bath method (bulk)

3.6.4  Dyeing Curve of Two Bath Dyeing Method

3.6.5  Process Flow of One Bath Dyeing Method

Table 17: Process flow of one bath method (bulk)

3.6.6  Dyeing Curve of One Bath Method for Bulk Production

3.6.7 Process Flow of After Treatment

Table 18: Process flow of after treatment

3.6.8  Curve of After Treatment

3.9 Testing of Color Fastness to Wash

• Method followed: ISO 105 C03

3.10 Testing of Color Fastness to Rubbing or Crocking

• Method followed: EN ISO 105×12

3.11 Testing of Color Fastness to Perspiration

• Method followed: ISO105E02

4. RESULT AND DISCUSSIONS

4.1 Color Measurement Committee (CMC) Pass/Fail Values:

Table 19: CMC pass/fail values

The above result shows that, one bath dyeing method is possible for all color and all shade%. Also possible for combination color shade.

4.2 Images of Dyed Fabric Sample

Table 20: Images of dyed fabric sample

4.3 Result of Color Fastness to Wash for Red Color

4.3.1 Change in Color

This graph shows that changes of color in wash fastness were same for both the sample. The change of color for both of the sample is 4.5.

4.3.2 Color Staining or Bleeding

This graph shows that no staining was on the nylon fibre and acrylic fibre for two bath method where as for the one bath method nylon fibre staining was 4.5. Acetate, cotton, polyester and wool fibre staining were same for both of the method. No staining in nylon fibre for two bath method where as one bath method this value goes on 4.5.

4.4 Result of Color Fastness to Wash for Blue Color

4.4.1 Change in Color

This graph shows that changes of color in wash fastness were same for both the sample. The change of color for both of the sample is 4.5.

4.4.2 Color Staining or Bleeding

This graph shows that no staining was on the nylon fibre and acrylic fibre for two bath method where as for the one bath method nylon fibre staining was 4.5. Acetate, cotton, polyester and wool fibre staining were same for both of the method. No staining in nylon fibre for two bath method where as one bath method this value goes on 4.5.

4.5 Result of Color Fastness to Wash for Yellow Color

4.5.1 Change in Color

This graph shows that changes of color in wash fastness were same for both the sample. The change of color for both of the sample is 4.5.

4.5.2 Color Staining or Bleeding

This graph shows that no staining was on the nylon fibre and acrylic fibre for two bath method where as for the one bath method nylon fibre staining was 4.5. Acetate, cotton, polyester and wool fibre staining were same for both of the method. No staining in nylon fibre for two bath method where as one bath method this value goes on 4.5.

4.6 Result of Color Fastness to Rubbing for Red Color

This graph shows that color fastness to rubbing in dry condition was same both the method. No deviation was found in wet condition.

4.7 Result of Color Fastness to Rubbing for Blue Color

This graph shows that color fastness to rubbing in dry condition was same both the method. No deviation was found in wet condition.

4.8 Result of Color Fastness to Rubbing for Yellow Color

This graph shows that color fastness to rubbing in dry condition was same both the method. No deviation was found in wet condition.

4.9 Result of Color Fastness to Perspiration for Red Color

4.9.1 Color Change

In this graph no difference was found for two bath and one bath method i.e. they were shows same properties under alkaline solution.

4.9.2 Color Staining

There was no significant difference between two method fabric sample and one bath method fabric sample. The value of color staining on acrylic fibre 5 and 4.5 for two bath method and one bath method respectively. No significant difference was found for both the sample.

4.10 Result of Color Fastness to Perspiration for Blue Color

4.10.1 Color Change

In this graph no difference was found for two bath and one bath method i.e. they were shows same properties under alkaline solution.

4.10.2 Color Staining

There was no significant difference between two method fabric sample and one bath method fabric sample. The value of color staining on acrylic fibre 5 and 4.5 for two bath method and one bath method respectively. No significant difference was found for both the sample.

4.11 Result of Color Fastness to Perspiration for Yellow Color

4.11.1 Color Change

In this graph no difference was found for two bath and one bath method i.e. they were shows same properties alkaline solution.

4.11.2 Color Staining

There was no significant difference between two method fabric sample and one bath method fabric sample. The value of color staining on acrylic fibre 5 and 4.5 for two bath method and one bath method respectively. No significant difference was found for both the sample.

5. COST ANALYSIS

5.1 Graphical Representation of Amount of Time

The graph showed that the one bath dyeing method required 1010 min time where as two bath method needed 1100 min. So that the one bath dyeing method saves 90 min. As a result, the one bath dyeing method provides the following benefits:

• Production will be increase.
• Labor cost will be decrease.
• Product can be delivers to the buyer within certain time. So, buyer will satisfy to the company’s authority.
• Save machine running cost. i.e. electricity, gas, and power cost.

5.2 Cost Saves for Extra Time

• 1KW hour = 1 unit of electricity
• 1-unit cost =5.5Tk (Approximately)
• Dyeing machine is 60 KW capacity
• So, it consumes 60×1=60 unit per hour
• Cost =60×5.5 =330Tk/hr
• Since one bath dyeing method save 90 (1 hour 30 min) minutes, so it saves 330×1.5= 495Tk (approx.) energy cost. [11]

5.3 Graphical Representation of Required Water

From this graph it can be stated that the conventional two bath dyeing method requires 64000-liter water per 1000kg fabric where as one bath dyeing method requires 48000-liter water per 1000 kg fabric. So, the one bath dyeing method saves 16000 liters of water.

5.4 Cost Saves for Extra Water

5.4.1 Cost in WTP

Table 21: Cost savings in WTP

So for 16000 liter of water saves 16 X 5.415 = 86.64 Tk(approx.) [11]

5.4.2 Cost in ETP:

Table 22: Cost savings in ETP

So, for 16000 liter of water saves 16 X 18.66 = 298.56 Tk (approx.)

Total cost for 16000-liter water = 86.64 + 298.56 = 385.20Tk

= 385Tk (approx.) [11]

5.5 Total Savings in Cost

Table 23: Total savings in cost

So, proposed one bath dyeing method saves 880Tk/1000kg (approx.) with 90-minute time.

6. CONCLUSION
P/C blend fabrics were successfully dyed by one-bath one-step dyeing process. This process was not cumbersome as other process because here all the existing chemicals were used which has not needed any special requirements. The novelty of undertake study is successful by maintaining the right process with the existing dyes and chemicals as is to give complete shade gamut, which will open up new avenues to dyeing factory owner to cater to the blend dyeing needs of the textile processors. The work is based on the well-established process of dyeing however will emerge in ready-made dyes as option to dyers to get rid of cumbersome shade matching at their end. Also, this one-bath one-step dyeing process has potential in offering savings in time, energy, water and labor. This process can be able to save approximately Tk.880 per 1000 kg of fabric with 90 minutes time. This research work demonstrates the specific possibility of a commercially acceptable dyeing process for P/C blend using one bath method.

6.1 Limitations

1. Due to Limitations in factory accessibility, it was not possible to follow all laboratory trials in bulk production for different shade%.
2. Due to limitations of lab dyeing machine dyes of different brand could not be used.
3. Due to lack of machine color fastness to light could not be tested.

6.2 Future Scope
Wet processing is responsible for wasting lots of water, energy and time, now the time came to increase performance of existing utility and to save more to reduce the production cost to stay in a tremendous competitive market. There are lots of scopes to work on the same topics to find out the more acceptable zone by using different dyestuffs which will reduce the production cost. There is a scope to dyeing of polyester cotton blended fabric in one bath after the scouring process without draining the scoured water. There is another scope to using other dye such as direct, vat, sulpher etc. instead of reactive dye for cotton part dyeing. It is not only an eco-friendly process but also the benefit will come in two ways. One will save more water and another benefit is to reduce the production cost.

7. REFERENCES

1. Arthur D Broadbent; “Basic principles of Textile Coloration”. Society of Dyers and Colorist (SDC), Bradford, West Yorkshire BDI 2JB, England, 2001.
2. Dr. Engr. Md. Nazirul Islam; “Apparel Fibres”. Mirpur, Dhaka, Bangladesh, 2008.
3. E.P.G. Gohl and L.D. Vilensky; “Textile Science”. New Delhi, India, 1983.
4. Raghavendra R. Hedge, Atul Dahiya and M. G. Kamath; “Nonwoven Fabrics Polyester Fibres”;www.engr.utk.edu/mse/textiles/polyester%20fiber.htm, 2004, (accessed 20 May 2014) .
5. Vilensky Dahiya, “Polyester Fabrics”; www.thomasnet.com/products/fabrics-27220532-htm, 2003, (accessed 20 May 2014).
6. Missouri;“Project Cotton- Chemical Composition of Cotton Fibers”; www.cotton.missouri.edu/Classroom-Chemical%20Composition.html, 2008, (accessed 21 May 2014).
7. Xiao Gao and Praveen Kumar Jangala; “Polyester Cotton Blended Fabrics”. Chaina, 2004.
8. R. Meena, Abhinav Nathany, R. V. Adhivarekar and N. Sekar, One bath dyeing process for PC blend fabric using physical mixture of reactive/disperse dyeing, Department of Dyestuffs, Institute of Chemical Technology, Matunga, Mumbai, 2013.
9. “Maintenance Manager, Alim Knit Tex Limited”; Nayapara, Kashimpur, Gazipur, 2014.

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Mazharul Islam Kiron

Founder & Editor of Textile Learner. He is a Textile Consultant, Blogger & Entrepreneur. He is working as a textile consultant in several local and international companies. He is also a contributor of Wikipedia.

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