photo courtesy of Texbond
Can one nonwoven fabric really do it all? Maybe not, but composites are coming close. From filtration and medical end uses to wiping and protective applications, composite nonwovens have earned a solid reputation among nonwoven consumers for their versatility, performance and quality.
One way to achieve these characteristics is to take advantage of different fiber combinations, a strategy that is working well for industrial nonwovens specialist Hollingsworth & Vose, East Walpole, MA, a company that uses high-tech fiber variations to develop a range of composites. H&V's Advanced Fiber Nonwovens (AFN) Group produces uniform nonwoven veils and mats from an array of specialty fibers such as para-aramid, PBO, carbon, glass, polypropylene, polyester, basalt, nickel-coated-carbon, copper-coated-carbon and stainless steel fibers. "The materials are used in a variety of composite applications," explained Michael Clark, director, Advanced Fiber Nonwovens. "These include corrosion barriers, ESD (electro-static dissipation), surface finishing, impact resistance, stealth technology, flame barriers, heating elements and EMI shielding."
Other recent developments from H&V include blends of glass and polypropylene for use as a fiber-reinforced thermoplastic compression molding material. Also new are basalt fiber veils and mats for use in flame barrier applications and stainless steel fiber nonwovens for use in EMI shielding and conductive substrate applications.
European manufacturer eswegee Vliesstoff GmbH also uses a variety of raw materials and hybrids-such as glass, carbon and aramid fibers-to create both composite materials and nonwoven compounds. In the composites area, the company sells multiaxial fabrics into industries including automotive, marine, power generators (i.e. rotorblades for windmills), aviation, transportation and lamination. Featuring high tear strength and strong performance at low weights, the fabrics are available in E5-E10 gauges, in 150-2500 gpsm weights and in widths up to 50 inches.
As for compounds, eswegee is working on several new nonwovens for filtration and automotive applications such as injection molding. "We intend to focus on more products for the future," stated Detlev Käppel, global sales director. "We are especially interested in the automotives industry where we work on combinations of glass and nonwovens in sandwich constructions in order to reduce shrinkage to almost 0% for acoustic parts." Mr. Käppel added that the company plans to install lamination equipment, most likely in 2006.
Interesting Industrial Ideas
Also in the industrial sector, Italian roll goods producer Texbond uses composites to meet increasingly technical demands in the roofing market. Texbond provides a range of inline laminates, incorporating different materials to achieve optimal solutions for roof insulation, housewrap, protective clothing and packaging. Customized multi-layer products are available based on specific customer needs.
Nordenia offers a line of composite fabrics for hygiene applications.
"Combining multi-layer breather membrane and film/highloft composites and adding highly reflective metal surfaces is the ultimate idea in the field of pitched roof insulation," commented Texbond's Alessandro Mottes. Texbond's breathable membranes are converted by converting specialist Valtech, France into multilayer highloft insulation pads. They incorporate in one light, single product the functions of a complex traditional insulation framework to prevent the release of heat from the inside, to avoid the reduction of heat insulation due to moisture, to allow residual moisture to dispel in the environment and to provide water tightness. In addition, the Texbond/Valtech product provides high reflection against heat coming from outside, consistently reducing air conditioning needs. "Incorporating such a solution into a new building delivers full optimization of energy consumption at high living standards," said Mr. Mottes.
Engineered composites are also a key focus for DelStar Technologies, Inc., Middletown, DE. The company uses its meltblown and netting technologies to create novel nonwoven composites in medical, filtration and industrial applications. "Essentially thermoplastic in nature, the meltblowns provide the functional performance while the nettings are used as support layers or bonding layers for laminating with various nonwovens, films and membranes," said Ashish Mathur, Delstar's director of meltblown technology.
Delnet mesh is used as a scrim replacement and for laminating with various nonwovens, films and membranes. Through the introduction of Delnet EP multilayered nets, DelStar has been able to engineer thermoplastic nets to meet a wider range of chemical affinity and bonding temperature requirements. This is achieved by coextruding different polymers with Delnet mesh in either two- or three-layer format.
DelStar has introduced Delnet mesh-based composites in four broad categories. In one form, the composite is produced with an absorbent nonwoven with the smooth, non-linting and porous Delnet mesh facings on one or both sides. A new composite has been developed by adhering a non-absorbent nonwoven, such as spunbond, to the Delnet mesh, which then allows the spunbond to bond to itself. In this form, the Delnet mesh serves as a bonding layer.
DelStar has also introduced pleatable composites for the filtration market by combining DelPore meltblown media and stiff Delnet mesh and Naltex netting, where the meltblown provides the performance and the Delnet or Naltex provides the stiff backing layer without compromising the performance of the media.
Very, Very Versatile
German hygiene specialist Nordenia Deutschland Gronau GmbH is also taking advantage of the benefits of composites to offer versatility and top performance to customers in the hygiene field. The company offers new three-layer laminates based on an SBS film (apertured and/or non-apertured) plus elastic bicomponent fiber spunbond surface covers. "Such a laminate is unique and Nordenia has applied for patents on its construction," said Georg Baldauf, Nordenia's product manager composites/elastic films. "Elastic composites used in baby and adult diapers are substantially improving the fit and comfort of such products." Nordenia's new three-layer laminates are designed to offer superior rubber-like elasticity while the apertured film offers breathability.
Gainesville, GA-based Atex Group is another company targeting increased performance through the use of composite nonwovens. "To offer more than one function in the same fabric has always been a dream for nonwovens producers. Since its inception, the nonwovens market has become increasingly demanding, and only through composite structures are we able to offer the best solution to major converters," commented Jeff Brooks, account manager.
Atex offers various solutions in different market segments such as wiping, medical and building/construction. In the wiping area, Atex has created special nonwovens that not only release the right amount of liquid under pressure but also offer mechanical scrubbing effects for use in a variety of cleaning applications on different surfaces. "Also, in keeping with converter demands," added Mr. Brooks, "strength and absorbency in very light webs have come to fruition only by combining different technologies through composite structures."
Atex composites also target building/construction applications. According to the company, the control of climatic conditions in housing requires modern solutions that can avoid the condensation of internal conditions and at the same time be able to waterproof walls and roofing structures "Composite nonwovens offer many protective advantages for valuable properties by offering additional qualities such as exceptional strength, impenetrable barriers, breathability, flame retardancy and UV resistance.
Freudenberg Nonwovens, Durham, NC, also sees composites as a sector ripe with opportunity. "The philosophy of Novolon Dimensional Fabrics, a business unit of Freudenberg Nonwovens, is to understand the needs of the customer and design a product that will provide the attributes and performance characteristics to meet these needs," said Carol Clemens, director of business development, Novolon Dimensional Fabrics. "Many times this cannot be accomplished with just one substrate. Composite structures are created to achieve these ultimate goals."
Novolon's deep molding technology is designed to add another dimension to a composite to impart additional performance attributes such as air flow, insulation, compression resistance and integrating conductive elements. The deep molding process imparts distinctive properties to woven, knit, and nonwoven fabrics that are attainable by no other process for many end use markets.
New pillows from Encompass Medical feature DuPont's Suprel composite technology.
Mighty Medical Market
Many companies are focusing on meeting requests for absorbency, breathability and barrier qualities through medical composites. "These three characteristics are requested more and more often in the same fabric," Atex's Mr. Brooks remarked. In the past, this was accomplished through chemical solutions with various negative impacts on the environment and the physical handling of the fabrics. "Atex's composites are designed to provide the desired performance during the extrusion process, thereby rendering controlled and permanent results."
Also in the medical arena, Encompass Medical, a division of Encompass Group LLC, is launching two new healthcare pillows made with DuPont Suprel composite medical fabric. This bicomponent nonwoven is based on new DuPont Nonwovens Advanced Composite Technology and is made of polyester (for strength) and polyethylene (for softness). DuPont Suprel was developed using input from nurses who participated in comfort studies conducted at North Carolina State University. The fabric was designed to deliver a high level of protection without compromising comfort.
According to Encompass Medical, the new healthcare pillows are the first of their kind to offer uncompromising patient comfort and fluid and stain resistance. Encompass Medical and DuPont will jointly promote the new composite-based pillows. Encompass Medical supplies disposable and limited-use medical products to the healthcare industry. The four manufacturing entities represented and supported by Encompass are: Albahealth, Avcor, The Pillow Factory and TechStyles.