19 October 2012 09:47 [Source: ICB]
Clariant is this year's overall winner and winner in the Innovation with Best Environmental Benefit category with its Advanced Denim technology that cuts water consumption dramatically
The drive to make denim production more sustainable is gaining momentum as producers, retailers and consumers become more aware of the environment and the earth's dwindling resources.
Manel Domingo, Manel Jimenez and Nuria Estapé (l to r) of the Advanced Denim team at Clariant's Denim Center in Castellbisbal, near Barcelona, Spain
The launch of Clariant's Advanced Denim technology could revolutionise the finishing and dyeing of a fabric that accounts for some 14% of world cotton production.
Through its close partnerships with textile mills, the Switzerland-based company had realised that using indigo dyes presented major limitations because of their ecological and environmental impact. Indigo has been used for more than 100 years and reacts with many different treatments such as bleaching, to give a variety of looks.
But indigo is not soluble in water in its natural agglomerated form, and cannot penetrate cotton fibre. Therefore, the dye molecules have to be separated first, which is done using the strong reducing agent sodium hydrosulphite. Then, dyeing has to be repeated from six to as many as 15 times to achieve an even colour, using huge amounts of energy and water.
Clariant knew it needed to use a different type of chemistry that enabled garments to look the same as their indigo-based counterparts. The first step was to find a family of dyestuffs that exhibited the same look as indigo. Clariant's Advanced Denim project leader, Nuria Estape, says the main limitation has traditionally been that other dyestuffs do not behave in the same way as indigo in terms of colour and effect.
"It was difficult to use our existing range of blues to make garments that looked the same as those made with indigo," Estape says. A second requirement was that the application process had to be more efficient and with a much improved ecological footprint.
So, some six years ago, company researchers began to look at sulphur-dye chemistry. They discovered and successfully produced dyes with a much broader spectrum of shades than usually possible with conventional indigo, such as blacks, greys and navies.
The Diresul RDT dyes, which are free of heavy metals, also only require a single, sugar-based bio-degradable reducing agent, which not only ensures sulphide-free effluents, but also eliminates unpleasant odours during application.
Clariant says the concentrated sulphur dyes are difficult to differentiate from, and display very similar behaviour to, traditional indigo dyes, but without their environmental problems. The typical "ring effect" is maintained, where dyeing does not penetrate into the core of the fibre, so every thread consists of a coloured ring with a white interior. This makes it possible to produce bleached effects such as a vintage or used look.
The dyes comply with the strictest eco-labels, including the Oeko-Tex Standard 10, a global test and certification system, the Global Organic Textile Standard and the bluesign standard. In addition, Clariant says it is one of the first companies to be awarded an EU Eco-label, known as the EU Flower label, for its sample collection made with Advanced Denim.
The dye is oxidised with efficient fixing agents to make it adhere to the cotton. In the same immersion tank, Clariant's Arkofil DEN-FIX is used to coat the fabric with a layer of starch to protect it during the stressful weaving stage.
An additional important advantage is that, thanks to the sulphur dye chemistry, the dyed garment can be washed down later using hydrogen peroxide instead of the chlorine normally used for indigo, which is responsible for forming aromatic halogen compounds.
In essence, Advanced Denim's Pad/Sizing-Ox technology has cut the number of vats needed from up to 15 in the traditional indigo process to just one, which has led to considerable improvements in denim's environmental footprint.
Compared to indigo dyeing, results from numerous trials have shown that Advanced Denim saves up to 92% water, 30% energy and 87% cotton waste, with the added advantage of no effluents.
Clariant calculates that if Advanced Denim technology were used to produce 25% of jeans worldwide, it would save 62m m3 (2.2m ft3) of water a year, equivalent to the water consumption of 1.7m people. It would also eliminate the need to treat 8.3m m3 of wastewater, and 220GWh of power would be saved with carbon emissions reduced accordingly.
The technology was launched as a concept about two years ago and Clariant has continued to improve the products and process since then, Estape says. Advanced Denim was designed to be used in textile mills' existing machinery, with no need for additional investment. Manel Domingo, head of research and development for special dyes, says that the equipment required to run the technology is very simple and is much less complex and expensive than existing machinery.
Clariant's technical advances caught the attention of German textile machinery company Karl Mayer, which is considered to be the world's leading manufacturer of warp preparation equipment for weaving. The two companies pooled their knowledge and concentrated on integrating the conventional ring dyeing process.
The result was that Karl Mayer revamped and refined its existing systems, culminating in the development of the Indig-O-Matic machine, an integrated modular concept for the denim industry which is based on Clariant's Pad/Sizing-Ox dyeing process. Key characteristics are its ability to be set up for smaller runs and its flexibility to react rapidly to changing fashions.
As well as its ecological benefits, Clariant says that Advanced Denim opens the door to new possibilities in denim design. Aside from the new range of colours and shades - from sky blue to graphite grey and olive green - colour fastness is excellent and much more reproducible, giving designers new freedom in using colour gradients, shading, imprinting, additional colours, as well as bleached effects.
Manel Jimenez, who is responsible for developing the application processes, says the response from textile mills to the technology has been very positive and some denim mills already have their own collections based on Advanced Denim.
Clariant's goal now is to introduce the technology to the major brands. Estape says that Clariant is working with several brands and retailers to develop new collections and to launch the concept to the end-consumer. The company is also developing some analytical methods so that in future consumers will be able to check the veracity of a garment's claims that it was made without using indigo.
Clariant is focused on innovation and sustainability, stresses Domingo. Company strategy is to only pursue projects that are geared to improving the environment, reducing energy and reducing the waste of world resources. "Advanced Denim is a first step and is a perfect fit with this concept," he says.
More than 20 people from Clariant worldwide actively participated in the development of Advanced Denim due to the complexity of the textile chain. People from research and development, application laboratories, production site, product management, technical support, marketing and communication were involved. Now, he adds, Clariant is continuing to develop more projects and expects to introduce some additional new textile chemical and dye products in the near future.
The company obviously hopes that Advanced Denim becomes a classic in its own field, just like the status of the jeans it helps to produce. As Domingo says, the commitment of the major brands to create new collections based on Advanced Denim will be key in seeing this new technology produce its full benefits for the environment.
Statistics say that an American owns eight pairs of jeans, while a European comes a close second with five to six pairs. How many of those in the future will be made with Advanced Denim?
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