Cotton Production for Denim Manufacturing

Cotton Production for Jeans Manufacturing:
The most important raw material in denim production by volume and value is cotton, and denim accounts for nearly 20% of global cotton production. As a natural product, the quality of cotton varies depending on its geographical origin as a result of different soil and climate conditions, and from season to season. 

Cotton fiber used for denim or jeans
Fig: Cotton fiber used for denim or jeans
As a result, the skilled mixing or blending of different fiber varieties is necessary to ensure consistent raw material quality as the basis for good product quality at the end of the production chain. This need for quality can conflict with environmental needs. As an example, good quality cotton fiber may depend on extensive irrigation, the use of fertilizers and various kinds of pest control. 

Globally, cotton production can be segmented into:
  1. Conventional cotton farming systems,
  2. Integrated pest management (IPM) systems,
  3. Organic cotton production.
The environmental pros and cons of each method are compared and discussed in detail in the literature. It is important to be aware that organic production may not always be the best option, if conventional and IPM systems make the best use of scare land resources and produce the highest yields. 

On the other hand, all support processes and products used to optimize cotton yields must be harmless to the environment as assessed through LCA, and should not have an intensive energy consumption or carbon footprint. It is important to promote the use of chemicals that are not harmful to the environment and that biodegrade to leave harmless residues. In addition, it is essential to optimize dosages of fertilizers to avoid excessive consumption of chemicals that may be environmentally damaging to produce and use.

One important aspect of cotton production is recyclability, and at the end of life of a garment, there are many possibilities for recycling it. High quality cotton fibers may be converted to super absorbent polymers by chemical modification, and can be used for the production of medical textiles such as diapers, incontinence products, etc. 

This may not apply to cotton from denim that was previously dyed and finished, but in that case the denim may be triturated and used for the production of non-woven felts to be used as thermal and acoustic insulation materials in automobile and construction sectors. It has also the potential to be converted into art and drawing paper, by proper dissolution and further deposition of the pulp. It may also be possible to produce cellulose in powder form, which can be used as fillers or for blending with other polymers to develop composite materials.

Denim cotton can also be used as a raw material for developing new types of regenerated cellulosic fibers. Cotton can be recycled via the lyocell process by dissolving used cellulose material and spinning a fresh cellulosic fibre from N-methyl morpholine N-oxide as a highly recyclable solvent for the spinning process. 

The lyocell fibres can be modified by the nozzle structure and other spinning conditions, and by adding products to the fibre production process, including crosslinking agents, softeners and other modulators. In the lyocell process, recycled cotton, other cellulosic textiles, newspaper or wood material can be mixed with fresh cotton to make cellulose yarn of appropriate quality for production of denim or any other cellulose based textiles. 

The benefits for environmental and sustainability parameters can be calculated for pure lyocell fibre denim and several blends such as 50:50 cotton/lyocell, compared with those of 100% fresh cotton using standard cotton (from Cotton Inc., United States) and lyocell (from Lenzing AG, Austria) production process parameters.

In the case of a 50:50 blend of cotton and lyocell, the saving would be about 50% of current energy use in conventional cotton growing and harvesting, as well as 50% of the chemicals such as fertilizers that are needed for cotton cultivation. Transportation costs and environmental impacts are comparable to those of traditional cotton production. Yarn production (spinning) from cotton/lyocell blends is well established and cost effective, with only the addition of extra spinning oil required to ensure an efficient process. 

About Author:

Mozaffor Hosen Sohel
Assistant Manager (Dyeing & Washing),
A&A Trousers Ltd,
Pubail, Dhaka, Bangladesh
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