As supply chain needs continue to change, both brands and consumers alike are looking for more environmentally friendly options. But as a lot of water is needed to make denim products, the environment is also polluted due to the use of chemicals. According to a study, 6 billion units of jeans are produced annually in the world. Each jeans uses 70 liters of water, 1kw/h of energy, and 150 grams of chemicals, which means an annual consumption of 420 million m3 of water, 6 billion kW/hour of energy, and 900,000 tons of chemicals. But nowadays consumer demand is sustainable products without sacrificing the look and feel of their favorite pair of jeans. It is possible to save water, energy and chemicals if everyone in the denim industry uses new water-free technologies. Let’s talk about some water-free denim technologies.
Some Sustainable Denim Processing Using Water-free Technologies:
Sandblast Finishing of Denim: This is a blasting process where denim fabric is blasted with a high-pressure stream of sand or other abrasive material to create a faded or worn appearance. Sandblasting is a modern technique that uses a special type of sand applied to specific areas of blue denim. Actually, it is a mechanical process. Very fine-grained powder and hard aluminum oxide has been used to sandblast denim. In the process, aluminum oxide sand mixed with dry air is passed through the nozzle at a very high speed to affect the sandblasting action. Sand removes color from certain areas of clothing and thus produces fashionable effects. After sandblasting, the garment is washed with enzymes and silicone softeners to increase fabric softness. Because of abrasion damage, increasing the ends per inch and picks per inch. Here, Denim garments are placed in a closed chamber and are instantly faded by the abrasive effect of the sandblast. The flow angle of the sandblast, an important parameter, is kept somewhere between 10 and 20 degrees on the surface. A properly set blowing angle is essential because a process with a higher blowing angle will result in a high fading effect, in addition to high damage to the fabric. Numerous operations exist to create the fading effect of fabric, but this one is sustainable and environmentally friendly denim processing.
Ozone Fading of Denim: Ozone fading is one low water-based denim processing where ozone gas is released. Ozone is released in the presence of sunlight because of the interaction of hydrocarbons, oxides of nitrogen, oxygen, etc. Later blue denim fabric turned yellow due to ozone reaction UV exposure. Although the ozone finishing of denim fabrics does not eliminate the use of water, it can significantly reduce the use of water, energy, chemicals, enzymes, and stones. The fading rate of the blue color depends on dyes and their solubility in fiber, and the diffusion of ozone in fiber. To wash denim by ozone, the garment is bleached with dissolved ozone in the water of a washing machine. Denim clothing can be bleached or faded using ozone gas in a closed chamber. The method is easy and environmentally friendly, because ozonized water after washing can be easily deionized by applying UV radiation. Ozone characteristically acts as a mild washing and sterilizing agent. Ozone bleaching can be accomplished by plasma processing.
Plasma Processing of Denim Fabric: Plasma technology has been used for textile treatment for the last few decades, but its technological development has not yet been done as such. Plasma is a partially ionized gas composed of positive and negative ions, electrons, neutrals, excited molecules, photons, and UV light. It can be used for nano-level surfaces modification for both natural and synthetic textile substrates without modification inherent bulk properties of fibrous material. Plasma was generated by electric discharge using polymerizing to non-polymerizing gaseous molecules for denim processing. The efficiency of the process depends largely on the nature of the gas used. Using conventional technology involves the use of large amounts of water and chemicals to create a faded look in the fabric. Laser and plasma technologies have shown the potential to create different surface effects on fabric without using a lot of water and chemicals. Chemically, a reactive plasma discharge has been used in various industries to modify certain surface properties of materials. Washing denim clothing is a polluting activity in the textile industry; where plasma reduces or completely avoids the use of water. Until now, plasma exposure has mainly been used to bleach blue and sulphur-dyed denim garments.
Laser Processing of Denim Fabric: Like plasma treatment of textiles, UV treatment has also been used to modify the surface of natural and man-made fibers. Many lasers capable of operating at different wavelengths and in different modes are available for surface modification of textiles. Surface modification by laser can be done in different ways, depending on the purpose of the surface modification, such as etching, ablation, deposition, evaporation, and surface functionalization. The purpose of the surface modification determines the type of laser to be used.
Lasers, which use a noble gas for generation, are typically also referred to as excimer lasers. They operate in the UV to near UV region, i.e, from 193 to 351 nm. The CO2 and Nd:YAG lasers are the most powerful. On the other hand, Excimer lasers can operate in the UV region and are strongly absorbed by polymers for photochemical reactions. However, it is difficult to expose large areas of polymer which increases the cost of production. While conventional technologies are far more beneficial in terms of mass customization, the production of faded jeans using those processes involves a large amount of water. On the other hand, a laser is a source of energy that can be directed at a desired object, with power as well as intensity being controlled. This technology is computer-driven and replaces the use of water, chemicals, and stone, yet it can create precise, repeatable and complex patterns. In addition, it can create excellent local effects on denim fabric.
Growth of Environment-friendly Denim:
What Percentage of Jeans are Made Sustainably?
It takes an average of 1500 gallons of water to make a pair of blue jeans. This includes growing and producing the cotton, but it does not include the water will use to wash jeans over time. A lot of water is wasted in making jeans. Only environmentally friendly manufacturing of jeans can reduce water wastage. Now 35 percent of the jeans are made more sustainably. About 6 billion pairs of jeans are made a year so that means 2 billion pairs are now being made more sustainably.
Advantage of Sustainable Denim Processing:
- Reduce water consumption.
- Reduce energy consumption.
- Reduce chemical use.
- Reduces harmful effects on the environment.
- Reduce harmful chemical effects on worker’s health.
Conclusion: Denim finishing is an important textile operation for adding value to denim
By clothes and specially decorated, makes attractive to young customers. Numerous operations exist on denim sanding, sandblasting, sand washing, snow washing, stone washing with enzymes, prewashing, brushing, rinsing and bleaching. Emerging waterless or less water-based technologies, such as laser, plasma, ozone and sandblasting, has also been sought after in terms of durability and makes for excellent fabric handling. Laser treatment has been found to be a useful tool. For good color fade of denim fabric with proper uniformity. Similar to laser treatment, Plasma technology can be used to replace conventional stone washing or enzymatic bio-stoning processes.
References:
