Polyfunctional reactive dyes by Huntsman:- Part 1

AVITERA™SE

Revolutionary Textile Dyeing Products Save Water

The next time you slip on a polo shirt from Lacoste™ or Marks & Spencer, you can take comfort in knowing the process used to dye the fabric is contributing to the sustainability of one of our most precious resources–water.

The mills that these two clothing brands buy fabric from are using revolutionary product AVITERA™ SE, created by Huntsman to significantly reduce water and energy consumption, as well as carbon dioxide(CO2) emissions during the dyeing and washing-off process.

Why it matters

By 2030, the world demand for fresh water will increase by 40 percent. Textile dyeing and finishing processes consume vast amounts of water – in the very parts of the world where it is most scarce. As environmental awareness grows, so does demand for textiles produced in more sustainable ways – yet at low cost.

Up to 26 gallons (100 liters) of water is needed to dye just two pounds (one kilogram) of cotton fabric. With AVITERA™ SE, water usage is reduced to just three to five gallons (15 to 20 liters) per two pounds of material. With the new dyeing technology, one quart (1.3 liters) of fresh water per person per day could potentially be saved in the major Asian textile processing countries such as China, India and Bangladesh.

How it works

Cellulose fibers, such as cotton, viscose or linen, are the most widely used textile fibers. Depending on the year and crop yields, about 30 millions tons of cotton are produced annually. By far the largest part of cellulose fibers is cotton. Pure cotton is mostly dyed using reactive dyes.

The dyeing process takes place in three distinct phases:

• Adsorption and Diffusion
  The reactive dye is adsorbed onto the cellulose surface and then diffuses into the fiber matrix.
• Fixation
  If conditions are favorable (high temperature and/or high pH), the reactive dye reacts with active sites in the cellulose during this phase (fixation), resulting in a strong covalent bond.
• Washing Off
  To obtain the required fastness properties, all these forms of unfixed, adsorbed dye molecules must be washed off the fiber.

Industrial practice has shown that with AVITERA SE, nearly 90 percent of the dye applied to cotton during dyeing is fixed, as opposed to 60 to 80 percent with conventional reactive dyes. This ensures higher yield.

Fabrics can be dyed and washed off at different temperatures and different quantities of water. Hot dyeing systems require a temperature of 176°F (80°C) to make the bond between dyestuff and fabric permanent. These systems also require boiling water and several rinsing baths to completely remove unfixed dyestuffs.

Conventional warm dyeing systems already offer the benefit of creating the necessary bonds at a lower temperature—140°F (60°C)—but still require a lot of water and high temperature for an appropriate wash-off.

AVITERA SE dyes help significantly reduce water and energy consumption and CO2 emissions since dyeing and the washing-off process never exceeds 60°C.With only five percent or less unfixed dye needing to be removed, instead of the usual 15 to 30 percent, the number of rinsing baths to obtain the required fastness properties is greatly reduced.

To ensure that AVITERA SE dyes achieve the targeted resource and cost savings, they must be correctly applied. Huntsman Textile Effects works closely with textile mills to adapt their production processes and guarantee excellence in operation, strict cost control and a sustainable system. Helping brands and retailers to coordinate with mills and communicate with consumers improves cooperation throughout the textile value chain, resulting in greater environmental awareness and more sustainable textile processing.