Full of Hot Air

August 17, 2005

versatile, efficient and cost-effective, air through bonded nonwovens have every reason to brag

Versatile, efficient and cost-effective, air through bonded nonwovens have every reason to brag

by Ellen Lees Wuagneux, Editor

Whether you know it as air through, through air or thru-air bonding, one thing is clear—this is one technology that’s not suffering from an identity crisis. Referred to as the “Rolls Royce” of bonding techniques, air through bonded nonwovens have a reputation for delivering high quality and high performance in a full gamut of end uses. With applications ranging from the most disposable to ultra durable markets, these nonwovens are used in hygiene end uses—such as acquisition, transfer and distribution layers and topsheets—filtration, specialty medical and industrial markets, geotextiles, bedding, fabric softeners and various other product segments. Capable of exhibiting either extreme loft or density depending on the application, air through bonded nonwovens are versatile enough to fit in just about anywhere.

Although air through bonding itself represents a small percentage of the overall industry, it defies straightforward classification because just about any type of web process can be air through bonded. Estimating market size and growth patterns becomes a challenge because of the vast number of product segments this technology penetrates and the fact that many air through bonded nonwovens serve as part of multi-layered composites or are classified under a web forming process (i.e. wet laid, spunbonded, carded, etc.).

A subsegment of thermal processing and a generic term that can refer to either bonding or drying, air through is a method of heating and circulating air literally through a nonwoven web, which is typically wrapped around a very large (up to 24 foot) drum. In the case of wet laid or spunlaced nonwovens, the air through process can be used to dry the web, while dry laid or carded substrates may use this technique as a means of bonding.

System Savvy Suppliers
Considered a “tried and true” technology, air through bonding is certainly not a new “up and coming” technique, despite the fact that the industry seems to be paying it more attention recently. Belying their significant presence, there are actually a limited number of machinery manufacturers specializing in this area. Likewise, due to the significant capital investment necessary to purchase such sophisticated systems—not to mention the R&D and engineering efforts they necessitate—roll goods manufacturers active in this segment tend to be larger, global players rather than smaller, more regional companies. Another factor in this equation is that air through bonding lines—pricey but known also for their durability—tend to be compatible with higher speed/volume manufacturing plants.

There’s no doubt about the critical role machinery plays in air through bonding’s ability to produce extremely uniform webs. One leading supplier of flat bed and rotary systems is The Honeycomb Division of Valmet Inc., Biddeford, ME, which specializes in air through bonding and drying machinery for the nonwovens and tissue industries. Elizabeth Belliveau, marketing coordinator at Valmet’s Honeycomb Division, commented on the importance of equipment in this process. “It takes a very advanced engineering system to handle multi-layered webs, deliver uniform and increased bonding throughout and regulate precise temperatures.”

Don Brown, director of marketing and sales for roll goods producer Colbond Nonwovens, Enka, NC, (formerly Akzo Nobel Nonwovens) concurred. “The key technological challenge in air through bonding is to control air temperature and flow. The entire control system is critical, which makes it a mechanically complicated technology.” Mr. Brown added that the company has been involved in this market for many years, with its well-known “Colback” products—all of which use thermal air bonding—having been launched in the early 1970’s.

Another worldwide supplier of air through bonding systems is Fleissner, Charlotte, NC—with headquarters in Egelsbach, Germany—which specializes in air through perforated drums in various widths and sizes and hot air ovens for the highloft segment. “These highly engineered systems need to be able to handle ever-evolving combinations of materials,” said Don Gillespie, company vice president. “New variations include thermal bonded spunbonds, thermal bonded cellulose fiber-based fabrics and thermal bond, air laid, carded and crosslapped nonwovens.”

Unlike other bonding techniques, the air through process almost exclusively uses bi- or tri-component staple fibers. Featuring either a sheath/core or side-by-side configuration, bicomponent fibers with a combination of polyester, polypropylene, polyethylene or copolyester are popular choices because they provide the lower melting point polymers required to create a bond. While on the one hand bicomponent fibers—inherently more expensive—tend to drive up prices, on the other hand less overall fiber is needed and a recent drop in price has made bicomponent fibers more accessible.

Even with some companies citing lower fiber prices, raw material costs continue to be a concern. In the hygiene market, for instance, stagnant demand is attributed by certain producers to cost-intensive raw materials. “There is definitely a slow-down in air through hygiene products because of high costs,” said one leading U.S. manufacturer. “Producers are looking for alternative, less expensive bonding methods.”

For Dr. Ronald Smorada, vice president-technology and development at the world’s third largest roll goods manufacturer BBA Nonwovens, London, U.K., bicomponent fibers are a key to growth. “With the increased popularity of bicomponent fibers, we should see increased demand for air through bonding,” he said.

Valmet’s Elizabeth Belliveau agreed. “Advancements in fiber technologies will lead the way in the thermal bonding sector. Another factor will be the continued development of multi-layered webs and composites, which will affect the way products are made. We may begin to see air through products in new applications,” Ms. Belliveau predicted.

There’s More Than One Way To Bond A Web
Many roll goods producers offer air through bonding as one of several bonding choices in a portfolio of capabilities that may also include traditional thermal bonding, calendering and adhesive or resin bonding. Air through bonding competes with hot oil or electric calendering in certain markets and—specifically in the area of acquisition layers—some manufacturers cite air through as a replacement for adhesive bonding.

One producer noticing this trend was Aldo Ghira, managing director of Tenotex SpA, Terno D’Isola, Italy, which specializes in air through bonded acquisition/distribution layers and composite products. “There is increasing interest, particularly in Europe, for air through acquisition/distribution layers. This is an area that was previously dominated by thermal bonded, resin bonded and needlepunched substrates.” Mr. Ghira added that growth is beginning to take place in the Japanese market but, due to a different diaper design, the market is only in the early stage of introducing acquisition and distribution layers.

Also commenting on growth in the European sector was Michael Haddon, the new managing director sales and marketing for Lohmann GmbH, Dierdorf, Germany, a company that has been producing air through bonded nonwovens for three years. “Demand has increased for air through bonded nonwovens in hygiene applications in Europe, which is our largest and fastest growing market. In terms of competition,” said Mr. Haddon, “it is mainly stemming from Italy and Eastern Europe.”

“We are seeing the strongest levels of growth for air through bonded nonwovens in Europe, our largest market,” said Lupi Stefano, marketing director for Italian roll goods producer Pantex Group, Pistoia. From its two air through bonding lines, the company supplies hydrophobic hygiene substrates—made of bicomponent polypropylene—for sanitary protection and baby diaper uses.

George Zuckerman, president of Doubletex, Toronto, Canada—a second generation roll goods producer that has been in business since 1910—also raised the issue of competition. “Air through bonding is replacing chemically bonded nonwovens in polyester highloft furniture, upholstery and jacket lining applications,” said Mr. Zuckerman. “In addition to taking some spray bonding marketshare, air through bonding competes with polyurethane foam in boot, pillow and apparel end uses.” Mr. Zuckerman also pointed to a recent trend towards increased thickness and density in air through bonded polyester products for end uses such as mattresses. “Here air through bonded nonwovens compete with densified foam, low-end cotton and shoddy waste products,” he said.

From the machinery sector, Fleissner’s Mr. Gillespie pointed to the highloft market, where air through bonding is making inroads as a replacement technology. “Highloft is a booming industry right now and we’re beginning to see spray bonding lines being replaced with thermal air systems,” he said.

Having The Upper Hand
Despite competition from other technologies, air through bonding continues to make strides in various markets due to its positive selling points. In addition to versatility, another key advantage is its ability to generate webs featuring excellent softness, drapability, rewet and high bulk.

BBA’s Dr. Smorada was one manufacturer touting the benefits of this technology. He pointed to the company’s “Reemay” spunbonds, which are air through bonded nonwovens containing a continuous filament matrix fiber and a lower melting copolymer. “One advantage of this technology is the ability to form a batt without compressing, which allows for increased thickness,” he said. Dr. Smorada also named benefits such as broad end uses and improved aesthetics. “The product does not have marks from point bonding, which, visually speaking, is an advantage. This process makes more volume available for use, whereas with point bonding, 15-20% of the bond area is fused,” he said.

Another important advantage is the fact that chemicals are not used, which means fewer headaches for manufacturers with regard to recyclability, waste and handling procedures. “It’s a very clean process,” said Colbond Nonwovens’ Mr. Brown, “because it does not involve binders or effluents. It’s simple from this standpoint, even though technologically it’s quite sophisticated. There is no need to replace needleboards or purchase chemicals, etc.,” he said.

Like any technology, air through bonding has its drawbacks as well. One negative aspect is the plethora of existing patents for the process itself as well as its products. “It’s a precarious area to get involved in” said one manufacturer, “in fact, in terms of patent infringement, it’s a minefield.” Currently the largest patent holder is roll goods manufacturer Kimberly-Clark, Dallas, TX, which holds four patents on technology and products.

New Directions, New Possibilities
In terms of the future of air through bonded nonwovens, manufacturers cited several potential areas of growth. According to Tenotex’s Mr. Ghira, “There is movement away from a continuous diaper layer and towards a cut-in-place acquisition/distribution layer,” he said. As a more cost-efficient approach, this trend should lead to increased volumes as well as added value in the form of increased thickness and fluid management properties.

Specialty flooring applications are the wave of the future, according to Colbond Nonwovens’ Mr. Brown. “Air through bonded nonwovens can bring performance in tufted flooring applications as primary backings,” he said. While volumes and growth levels remain small in this market, Mr. Brown predicted that this will be a potential area for growth. Mr. Brown also cited growth for nonwovens in carpet tiles, a related market where the company saw more than 10% growth last year.