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Process minimization of knit garment-dyeing by nebulized system on e-flow machine

Preface

Bangladesh has started its journey in the RMG sector in the late 1970s. Since then, this RMG sector has been playing an important role in the economy of Bangladesh.

At present, Bangladesh is considered as one of the major suppliers of readymade garments to the global market with around 6.3% market share[1]. In the fiscal year 2019-20, the export value of ready-made garments (RMG) in Bangladesh amounted to approximately 27.95 billion U.S. dollars. contributed over 83.2 percent of the country’s total export earnings by contributing 12% to the total GDP[2].

Whereas from Knitwear items earnings stood $13.67 bn & Woven items earned $14.04 bn. This was a decrease from the previous year, which amounted to just over 34 billion U.S. dollars[3]. Although the sector now dominates the modern economy, has given the opportunity of employment to millions of unemployed, about than 4 million workers of which most of the workers are women.

Today’s global market is versatile of the consumer’s demand, and Bangladesh needs to focus more on sustainable practices. They require an innovative strategy to meet the consumer fashion demand with some ethical requirements that will help Bangladesh to become a hub of the textile & RMG sector.

According to the expert’s suggestion, a sustainable approach can be the more effective way of sustaining into the global competitive market.

For sustainable concept, it stands for three pillars where water is involved more like the natural resource that cannot be defined the importance by its monetary value[4]. An enormous amount of water is used for making one T-shirt, which defines how much water is consumed per month in one industry.

The water level is decreasing day by day in industrial areas. We have to focus on the utilization of this resource. And from that conception, I choose this project that will help us utilize this water resource.

Problem Statement: On Knit garments, after desizing, we have to run a mordanting process for adjusting the dyes on the dyeing process, and this process consumes a huge amount of water. Traditional mordanting process water consumption is on an average 8 liters/kg of the garment while our proposal benchmark is 1.5 liters/kg.

Industry owners as well as the environment, are affected because of the high water consumption with chemical consumption in Conventional Processes. It is required boiling temperature to run the mordanting process that affects the surrounding environment and industry cost management. If we can optimize the mordanting operation as result could be saved water consumption.

Introduction

Knit garment-dyeing has been used widely in the global fashion industry. In knit garment nebulized dyeing, dyeing is done through the spray system but mordanting is done with the conventional system with a high liquor ratio. And our focusing area is the nebulized (spray) mordanting process that would be a great Value Addition by resolving precise the issue.

At present, in the conventional mordanting process, the industry benchmark is 8 liters/kg liquor ratio for knit garment dyeing that requires 6 gm./liter mordants with 1.5gm/liter caustic at 50˚C. This entire system is used as a baseline to compare with our proposed process.

In nebulized dyeing, we use a 1:1.5 liquor ratio. This 1:1.5 liquor ratio is the best practice for spray dyeing in our selected factory where the experiment was conducted. So, we use this ratio for the further procedure by applying the spray mordanting technique.

What’s the e-flow machine?

e-flow-machine-Main-Tank
Main Tank: This is the main tank of the e-flow machine where chemicals & garments get the interaction for making desired shade, adjusted by its controlling board.
Chemical is sprayed by using the nozzles from the mixing tank.
Capacity: 35kg-45kg

The nebulized dyeing system is the new sustainable concept of knit garment dyeing, developed by Jeanologia, a Spanish company in developing eco-efficient technology.

e-flow-machine-spray-nozzles
Spray Nozzles: These nozzles are used to spray the mixed chemicals into the main tank.
This machine has 6 nozzles which are controlled by the NBP% (Nano Bubble).

The e-Flow technology transfers chemicals into garments through the spray nozzles where water and the right quantity of chemical products forming the nanobubble skin and distribute themselves as the carriers of the chemical products.

e-flow-machine-mixing-tank
Mixing Tank: Dyes & Chemicals are mixed here, and passed to the main tank through the spray nozzles with the pipeline.
It has a board for flowrate& NBP% controlling

Industry benchmark

It’s a new process that’s why we use the dyeing benchmark as the industry benchmark. At present, in the conventional mordanting process, the industry benchmark is 8 liters/kg liquor ratio for knit garment dyeing that requires 6 gm./liter mordants with 1.5gm/liter caustic at 50˚C. This entire system is used as a baseline to compare with our proposed process. In nebulized dyeing, we use a 1:1.5 liquor ratio as the best practice for spray dyeing.

Background or rationale

This proposed project is needed for economic & environmental reasons both within and outside the business that will reduce water consumption with chemical consumption, and as resulting decreased cost & meet the sustainable requirements.

Experimental procedure:

Materials & chemicals

In this project, some blended t-shirt were used. Nebu Wet V and Caustic were used as applied chemicals.

Desized garments were used for implementing the proposed mordanting process for creating the affinity of the garment to the dyestuff.

Garment Quantity-     2.43 kg

M:L – 1: 1.5  , total liquid  = 3.65L

Flow rate:  12litre/hour, Machine RPM :22

Time—22min, NBP- 130%, and keeping in Homogenous.

First rinse with caustic addition with a 1:8  ratio, Caustic 1.2gm/litre (29.16 gm)

Doing soft hydro

Loading garments into the Machine

Running the machine with garments (4 minutes)

Making mordanting liquor: Nebu wet V 17gm/litre( 62.05gm) and fill it into the control chamber tank

Spraying chemical into the garments by nozzles by 25 mintues then keeping in homogenous state.

Hydro for 30 seconds

Dyeing and further processes were done according to the conventional system to get the final products.

Result and discussion

As the spray system replaces the traditional process, excess water consumption has been reduced, referring to about 6.5 liters/kg water.

Table2: Comparison between conventional and nebulized mordanting process.
Key points Conventional Mordanting Nebulized Mordanting
M:L ratio 1:8 1:1.5
Mordant 6 gm./liter 17 gm./litre
Caustic 1.5 gm./litre 1.2 gm./litre
Temperature 50˚C Room temperature

As a result, the new mordanting process with existing machines have a new functional ability that saves a vast amount of financial value of the organization, and that will meet the requirements of sustainability in the global markets (Table 02)

consumption-nebulized-mordanting
Figure 1: Overview of consumption in nebulized mordanting.

This chart-01 shows that this proposed process can save water consumption with chemical consumption that has a huge impact on the business profit and the environment.

Recommendation

In this project, a new sustainable process of mordanting is introduced. It’s less labor-oriented with high financial impacts (Fig: 02) because of an automated machine.

Cost-comparison-conventional-nebulized-mordanting
Figure 2: Cost comparison between conventional and nebulized mordanting.

This experimental process shows that this nebulized mordanting system is the economical & sustainable process for knit garment-dyeing on the e-flow machine. That system will bring an extra advantage to the competitive global fashion market.

Feasible and viable

This proposed process is more workable for the sustainable industry as we have learned it’s less labor-oriented. We should do this process in bulk production widely for its easily applicable by installing the e-flow machine that would be a significant advantage to define its activity for the production floor.

Nebulized process Market Barriers

  1. Lack of proper knowledge about e-flow machine
  2. Lack of high investment
  3. Having lower loading capacity

Conclusion

Water is a natural resource, so it’s not produced by us as we want. We have to focus on how to utilize this natural resource.

If we can reduce water consumption in the mordanting process which consumes water almost 10 % of the total consuming whole dyeing process so that gives the extra advantages which are about 81.25% water consumption could be reduced compared to the traditional mordanting process that shows a great financial impact to the organization.

This process also reduces chemical and energy consumption because the process can be worked at room temperature which is less than the conventional process.

To sum up, This proposed process can bring an extra dimension to the sustainable garment-dyeing system if most of the industries implement this proposed process by installing the e-flow machine.

Acknowledgments

Special thanks to-

Engr. Morsalim (Manager- Sales & Technical, Officina+39 (BD) Ltd.),

Engr. Md. Mehraz Hassan (Deputy Manager- Sales & Technical, Officina+39 (BD) Ltd.),

Engr. Sheikh Rubel (Manager-Operation, Epyllion Washing Ltd.) for their cooperation.

If anyone has any feedback or input regarding the published news, please contact: info@textiletoday.com.bd

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