Becoming Part of the Solution

As interest in environmental sustainability grows, Ciba is taking an innovative approach to presenting colorants for polyester carpet fiber.

By Chris Holodak

Can Ciba colorants help to defer or halt the impending water crisis? Probably not. But using them to color polyester carpet could open the door to exciting possibilities for saving energy and water thanks to Ciba’s broad palette of colorants in the environmentally friendly process of solution-dyeing.

Solution dyeing is a carpet coloring process that’s becoming more widely used thanks to the strong global move towards conservation of resources and energy, especially in industrial applications. Solution dyeing can save considerable amounts of energy and water because the color is added to the fiber polymer at the hot-melt stage, just before the fiber is extruded. The traditional way of coloring carpet is by a process known as exhaust dyeing (or bath dyeing), which involves immersing fiber, yarn or finished carpet into colorant solution.

“A typical masterbatch process for solution dyeing uses about seven gallons of water during production of the concentrate, needed to color up one ton of extruded fiber,” says Marketing Manager Tony Judge. “Compare that to the typical exhaust dyeing process, which can use up to 4,000 gallons of water to produce one ton of dyed fiber! And, adding color to a polyester fiber line requires virtually the same amount of energy as running uncolored fiber.”

But why polyethylene terephthalate (PET)? The main reason is that PET — the most common polymer used in water and beverage bottles — can be recycled and reused in carpeting more easily than polyamide or polyolefin, the two next most common carpet raw materials. In addition, the color palette for solution dyed PET is more diverse compared to that of solution dyed polypropylene. Plus, deeper colors are possible, especially in fine fiber applications.

The "Polyester Color Continent" is a very useful indication for carpet designers, showing the color space available at a medium depth of shade using Ciba colorants in polyester fiber.

The need for solution dyeing for polyester fiber came about, at least in part, because of a mandate currently in place in northern Georgia, in the United States, where there is a severe water shortage. Northern Georgia is often referred to as the carpet capital of the U.S., because the majority of carpet is produced there. Recently, plants have been asked to cut back on their water usage by at least 10 percent. In addition to government guidelines, many companies in the region have committed to reduce water consumption by as much as 25 percent.

The two main benefits of Ciba’s colorants for solution-dyed polyester fiber are environmental sustainability and the ability to reproduce the trend colors from the Color Evolution Guide. The full scope of coloristic possibilities offered by solution dyeing can be seen in a separate brochure highlighting the “Ciba Color Continent”, which maps possible colors that can be achieved on a PET substrate with Ciba colorants.

“We have been talking about the technical benefits of solution dyeing for a long time but the idea of environmental benefits is new and meshes well with an awakening by the entire country that our resources (energy, water, land) have to be used more wisely than in the past if we are to leave our children and grandchildren a planet in good shape,” says Marketing Manager Greg Perrone.