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Coatings and finishes enhance fabric performance

February 5th, 2016 / By: / Feature

Researchers are constantly working to improve the performance of water-based coatings. Photo: Alexium International
Researchers are constantly working to improve the performance of coatings and finishes. Photo: Alexium International

In today’s demanding technical fabrics markets, the fabric itself is just the beginning. For the end product manufacturer to get the performance qualities necessary to meet today’s stringent regulations and to satisfy the end customer’s high expectations, it is likely that the fabric will be coated and/or laminated with other materials. In some cases, it may be coated for one purpose, such as fire retardance (FR); in other cases, it might have multiple enhancements. But in either case, it’s unlikely that the end customer will be aware of the coating.

It’s what you don’t see

Alexium International provides an eco-friendly, non-halogen based chemistry for FR solutions in textiles, particularly for high synthetic blends, such as nylon and polyester. The company provides its products for coating textiles used in home and commercial furnishings. Its phosphorus-based, aqueous solution provides an FR finish that doesn’t affect—and may even enhance—the physical properties of that fabric.

“We have to be mindful of all textile properties and not just the FR, so that to the final user it feels and acts the same as any fabric—if not better,” says Alexium’s Mark Valdario, technical sales, North America and Europe.

“It’s hard to make any fabric FR, through a surface treatment, that can retain its original properties —softness, for example. In home furnishings, foam and latex mattresses are required to provide non-leeching, environmentally friendly FR protection, but you still need to maintain the softness and non-greasy feel,” he says.

Silicone coatings also have a nice drape and feel, a soft hand, and provide a low-cost vapor barrier, making silicone attractive for textile coatings in extreme sports and camping equipment. North American business director Ronald Hanks, Bluestar Silicones, York, S.C., sees greater movement into these areas.

“Typically urethanes are used, but the sun will degrade it over time so manufacturers of high-performance lightweight tents are seeing the benefits of silicone due to less UV degradation,” he says. “We’re hoping that gradually it will move into higher volume markets.”

Bluestar is one of the few fully-integrated silicone manufacturers in the world, according to Hanks. Bluestar’s products are also used in industrial settings for conveyor belts, welding blankets, drapes and aprons.

The move to water based

APV Engineered Coatings, Akron, Ohio, is a custom coatings manufacturer, with growing sales in products for industrial fabrics. Founded in 1878, the company began promoting and engineering finishes for textiles the past 12-15 years-with a specific purpose.

“There were performance issues that needed to be addressed with a coating,” says Erin Brown-Neff, director of marketing and business development.

A good part of the reason is the U.S. government’s phase-out of C8 (Perfluorooctanoic acid or PFOA), determined to be harmful to humans and the environment. C8 is highly effective, however, in repelling liquids, particularly oil-based substances. But with the PFOA shift, coaters and textile manufacturers are making the move to new finishes or coating technologies rather than continue by using C6 (or even C4) formulations, which are less effective than C8.

APV provides water-based and solvent-based treatments that can be used on vinyl and more recently, woven fabrics and leather seating. “Our Vynguard® Anti-graffiti coating is stain resistant, low in gloss and is flexible, but it also has abrasion performance so, in the case of leather, it can withstand further material processing, and maintain the leather’s soft feel,” she says.

In terms of its textile business, APV engineers coatings primarily in five major markets: automotive, marine, outdoor building products, seating and wall coverings.

The CLI Group, Paterson, N.J., converts customer materials into custom-engineered products using its environmentally friendly, water-based coatings and adhesives. “We’ve been water-based for a long time,” says Daren Silverstein, president. “Water-based coatings and adhesives are becoming more capable in meeting customers’ needs because of advances in polymer chemistry and more suppliers getting into it.”

In the distant past, the easiest thing to do was [C8-based] solvents, he says, without thought that the performance characteristics could be done any other way. But with today’s more rigid environmental standards, it’s difficult to use solvents because of the challenges involved with handling them and disposing of potentially harmful substances.

Silverstein says his company has been able to achieve today’s high standards for adhesion, peel performance and water holdout using water-based chemistry. “We probably have some retains that are going on 15–17 years and they still work,” he says.

Case in point, a Barbie® game manufacturer needed a carrier sheet where the adhesive stayed with the liner, not the fabric, which is standard, he says. “In this case, the carrier sheet kept it rigid so it could go through the printer. We probably made millions of yards of this stuff. They made hundreds of thousands of these games and each one had eight sheets of fabric.” He suspects that many of these games are still around because of the product’s durability.

Unique challenges

APV Engineered Coatings has developed new formulas that will address what may be a surprising industry concern: seating materials and Americans’ love affair with blue jeans. “The dyes in denim are staining the seats!” says Brown-Neff. “It’s a huge issue.”

This is especially problematic in automotive seating. Formulations using C8 (most commonly 3M’s Scotchguard™) had the stain performance that could restrict blue jean dye. “It did perform,” says Brown-Neff. “So now without C8, the problem has resurfaced, especially automotive and contract seating.”

“We have a lot of upholstery manufacturers who need a coating that will pass the automobile manufacturers’ blue jean dye test, have that soft, leather-like feel, will resist stains and have a low sheen or gloss,” she says. The company’s Vynguard® is a polymer technology that passes the blue jean dye test. “That’s been a game changer for us,” she says.

Automotive seating is also an important market for Alexium’s products, particularly with that industry’s growth since the recession. In the end, it’s about choices in technologies in coatings.

“We have access to a lot of auxiliary treatments to use in conjunction with our FR treatments,” Valdario says. From anti-crocking technology (color won’t rub off your jeans), to water repellency treatments, to antimicrobials, “The list goes on and on,” he says. “The coaters … they make the magic happen from the finishing side.”

Janet Preus is senior editor of Advanced Textiles Source.