Feel The Stretch

By Sandra Levy, Associate Editor | June 7, 2011

The nonwovens industry is developing innovative technologies to help producers incorporate more stretch into the design of hygiene, medical and industrial products, responding to increasing demands for better fit, comfort, elasticity and recovery

The nonwovens industry is developing innovative technologies to help producers incorporate more stretch into the design of hygiene, medical and industrial products, responding to increasing demands for better fit, comfort, elasticity and recovery

Make no mistake. Baby boomers are not going to wear adult incontinence products that are not comfortable, breathable, soft, quiet and aesthetically pleasing. And parents want diapers with the same qualities so their babies are comfortable and have the freedom to move and play. As the hygiene market increasingly demands these attributes, other sectors such as medical and safety apparel are waking up to the awesome benefits of stretch for nonwovens. And the nonwovens industry is heeding the call.

From diapers to adult incontinence products to wound care fabrics to surgical gowns and drapes to safety vests for first responders to uniforms for the military, the demand for fabrics that provide better fit, comfort and breathability is skyrocketing. So it is no wonder that new technology is spawning a new wave of stretchable options.

“We have seen stretch evolve pretty significantly in the last five years,” said Courtney Korselt, global communications and insight manager, Hygiene Adhesives of Bostik. “When I say stretch, I mean the side panel or the ear—where it’s fastened— which started coming out in premium diapers but since then we have seen a migration into private label and non-premium diapers. We have done a survey and in the U.S., at least 90% of diapers have stretch in them.”

Global hygiene brands like Procter & Gamble has led the charge in this area, first incorporating stretch in premium diapers like its Swaddlers or Cruisers lines and later incorporating it into its full line.

“We are always looking for ways to improve the diapering experience and connect those technical insights with insights from moms. When we first launched diapers, they didn’t have tabs and had to be attached with pins. As we move along our journey of creating diapers consistent with our equity of caring for babies’ happy, healthy development, we bring new technologies and innovations to the product to make diapering just one less thing moms and dads have to worry about as they do their important work of parenting. Stretch has allowed better fit to improve not only technical absorbency performance, but play and movement,” said Tricia Higgins, a P&G spokeswoman.

Incorporating more stretch into the design of the hygiene product poses many challenges. For one, the area of stretch is an intellectual property minefield as companies have worked hard to protect their advancements in the area. Additionally, adding stretch to one area of the diaper can change the schematics of the rest of the product design—weight, absorbency, fit, etc. “There needs to be a translation between design and performance,” explained Christophe Morel-Fourrier, global technical marketing manager, hygiene adhesives for Bostik. “Adding stretch changes the chassis of the diaper and you have to consider the entire design of the diaper anytime you add or take away a component. Additionally, when you add stretch to one area of the diaper, it can affect stretch in another area.”

An adhesive supplier, Bostik provides the adhesives that bond the nonwoven material with stretchable films, which is currently the stretchable engine favored in the hygiene market, as well as adhesives that attach this laminate to the diaper chassis. Other forms of stretchable materials found in hygiene products include single substrate nonwovens and elastic strands and nettings.

A Whole New World
The focus on stretch has created new markets for nonwovens beyond hygiene and the ability to incorporate stretchability into nonwovens is largely because of developments and innovation on the polymer level.

Kraton Polymers offers three polymers that give customers the ability to make elastic bicomponent spunbond fabrics using MD6705 and G1643 and elastic laminates using MD6717 and MD6705 in a meltblown fabric. All three polymers are based on the company’s fully hydrogenated styrene-ethylene/butylene-styrene block copolymers that were specifically designed to spin well in spunbond and meltblown applications.

James Dieter, vice president of market development said, “Our polymers are true elastomers that offer customers the ability to tailor their nonwoven offerings to improve fit, softness and to provide elasticity. Bicomponent spunbond nonwovens produced from Kraton’s elastomeric polymers allows for bi-axle stretch rather than directional stretch (CD or MD). This creates more comfort along with a wider range of areas to be used in. Many textile applications call for flexibility, drapeability, breathability and ultra softness with excellent stretch and recovery. Kraton elastomeric polymers meet these challenges and create stretchable materials including nonwoven fabrics and bicomponent fibers.”

Emphasizing that customers are asking for more versatility from their spunbond and meltblown lines, Mr. Dieter said, “This allows them to make higher value and higher performing products for disposable and durable fabric applications. We offer the ability to make truly elastic spunbond and meltblown fabrics.”
Kraton’s new technology is based on important attributes from its block copolymer technology (narrow molecular weight distribution, precise control of molecular structure) and using these attributes to design elastic molecules/polymers specifically for high-speed fiber spinning.

“There have been multiple test runs on Hills and Reicofil spunbond lines to prove the commercial viability of these polymers,” said Mr. Dieter.

In addition to improving fit, reducing noise in hygiene and adult incontinence products and medical applications is a trend that is gaining traction.

Kraton is working with North Carolina State University and other customers to develop soft, elastic durable fabrics for high performance clothing applications such as sportswear, uniforms, shoes and safety vests. “Better fitting garments for protective apparel that are lightweight and breathable while allowing stretch and recovery in critical areas such as shoulders, elbows and cuff areas are also in demand. High performance clothing manufacturers have been looking for durable elastic nonwoven fabrics that can provide the benefits of traditional woven materials while creating lighter weight and softer alternatives. The ability to be dyeable and/or printable with the proper choice of sheath material is of great interest,” said Mr. Dieter.

Propylene-Based Elastomers
ExxonMobil Chemical has moved forward in the hygiene and personal care markets with its Vistamaxx propylene-based elastomers. Targeted to a wide range of market segments including hygiene absorbent products (HAP) such as diapers, personal care, medical, filtration, and industrial applications, Vistamaxx propylene-based elastomers are being used commercially in elastic hygiene applications in Asia, America and Europe.

“Vistamaxx propylene-based elastomers, converted either as film or as fibers, are persuading nonwovens and diaper designers to rethink component and diaper construction and manufacture,” said Olivier Georjon, global nonwovens market development manager.

He added, “It takes multiple forms from full nonwovens to film-nonwoven laminates, in a range of end-products from baby diapers, training pants and adult incontinence products. Multilayer constructions of pure Vistamaxx propylene-based elastomers with other polymers can be designed to provide good elastic performance to avoid diaper leakage, combined with pleasant touch, feel and aesthetics. Used as elastic ears or tabs, such fabrics run very well at commercial speeds on diaper fabrication lines, and resulting diapers have been validated by consumer panel tests. ”

Emphasizing that brand owners are looking for alternative elastic solutions that provide similar elastic performance, enhanced aesthetics and breathable elastic components with better comfort and fit, Mr. Georjon said, “Large elastic ears are now common in mature regions and are starting to penetrate emerging economies.”

According to Mr. Georjon, manufacturers of nonwoven fabrics are looking for innovative ways to introduce differentiated products that address the needs of a range of application sectors. They are also seeking safer, more sustainable products that deliver cost-effective functionality to meet customer needs and ways to tailor the properties of fabrics to meet different customer needs.

“Polyolefin expertise, technical proficiency and application know-how enables ExxonMobil Chemical to develop solutions which will add value to customers across the value-chain. Vistamaxx propylene-based elastomers are inspiring the development of new, breakthrough nonwovens by enabling innovative designs and simpler construction, while enhancing performance at reduced costs. Many innovative product solutions, including commercial elastic hygiene applications, have been developed because of the possibility to target and balance properties including elasticity for simpler construction, better comfort, fit, and good leakage protection and softness and drapeability for touch and comfort,” said Mr. Georjon.

Polyolefin Elastomers
Another key player, Dow Elastomers has been stretching ahead with the following polyolefin elastomers for hygiene: Affinity Polyolefin Plastomers; Engage Polyolefin Elastomers; Infuse Olefin Block Copolymers and Versify Plastomers and Elastomers.

Alastair Hill, Dow Elastomers’ global marketing manager for Health & Hygiene said, “Brand owners and the marketplace are requesting softness and cloth-like aesthetics. Elastomers can be used to help create softness and the cloth like aesthetics. Dow has a very broad portfolio of polyolefin elastomers, which gives us the ability to work with converters and customers to tailor the solution to exactly what the performance requirements are. If an increase in elasticity is required we would recommend Infuse Olefin Block Copolymers or if softness is required we would suggest Versify Plastomers and Elastomers to be blended with polypropylene for the nonwovens.”

Mr. Hill explained that Infuse Olefin Block Copolymers are a very novel polymer structure. “We’ve been able to design into the architecture of that polymer a unique backbone that gives increased elasticity as well as processability, toughness and improved sustainability. Our customers may use it at a 100% or blend it with other Dow elastomers to create a film and then laminate that film to nonwovens to create a laminate. We also have programs with a number of customers in a number of geographies to develop extensible nonwovens, stretchable nonwovens –where the ultimate goal is an elastic nonwoven. We have multiple programs where customers are working to develop these solutions using for instance Infuse olefin block copolymers.”

Elastic Laminates
Experienced film supplier Tredegar Film Products has created several lines of elastic laminates.
FlexAire elastic laminates are supersoft, high stretch laminates for diaper ears and side panels in the baby and incontinence markets. FlexAire elastic laminates are also used as a breathable waistband.
Tredegar also offers FlexFeel elastic laminates, high performance laminates used for diaper ears and side panels in the baby and incontinence markets. FlexFeel elastic laminates feature a distinctive stitch-like bonding pattern that provides a textile-like appearance and reduces linting and pilling, while simultaneously maintaining softness.

The company’s FabriFlex elastic laminates are high stretch laminates used for diaper tabs and ears in the baby and incontinence markets. FabriFlex elastic laminates feature a distinctive bonding pattern that suggests robustness for the tabs and offers a soft quilted appearance for ears and side panels.

Finally, Tredegar’s ExtraFlex elastic films are high performance films designed for stretch in either machine or cross direction. ExtraFlex elastic films are typically used for waistbands and side panels in the baby and incontinence markets.

Matt O’Sickey, global product marketing manager said, “Tredegar is able to provide a full range of elastic performance for tabs, ears, waistbands, and side panels for both open tape-type and pull-on pant-type diapers in the baby and adult incontinence markets.

Beyond providing reliable performance, Tredegar also recognizes different markets and applications require different aesthetics. For that reason, Tredegar offers elastic laminate solutions with multiple options for visual perception, softness, and breathability.

We also strive to look beyond component-by-component performance and take a holistic approach providing the comfort-performance balance required in a sophisticated diaper. For example, in considering the trend towards thinner, higher SAP containing diapers, we look at how combinations of diaper ears, waistbands, and high performance apertured film acquisition distribution layers, such as AquiDry Plus, can achieve the greatest comfort, dryness, fit, and leak resistance.”

Sandler’s Entrance
Another key player, nonwovens producer Sandler offers materials for applications in diapers and other hygiene products. Sandler offers a soft and light material under the names sawabond and sawatex, featuring a high elongation at low force and a high CD tensile strength at maximum elongation. A newly developed thermo bonded material under the sawabond name for this application also offers high softness and high extensibility.

Sandler is also a player in the medical sector, offering sawasoft directionally elastic carrier materials for wound dressings and nonwovens for other wound care products that feature excellent elasticity.
Ulrich Hornfeck, vice president of sales, logistics and purchasing said, “These nonwovens allow the skin to breath due to their air permeability and are therefore ideally suited for medical applications. In various stretch applications for diapers and other hygiene products, utilized materials have to offer extensibility in order to adapt to any movement and to ensure optimal fit. They also have to be soft and feature excellent tensile strength at the same time. The recovery rate is another important feature. The material has to withstand stress tests where its remaining stretchability is measured. Even after frequent utilization, the materials in question have to feature extensibility and still retain their shape.

In medical applications, extensibility is needed to ensure optimum performance and comfortable use. Especially for wound dressings, the materials should also be air permeable in order to allow the skin to breathe and stay dry,” said Dr. Hornfeck.

Micrex Corporation has been making strides developing technology which imparts properties of softness, extensibility, conformability, stretch, drape, hand, absorbency, bulk and decorative effects to nonwovens, films, textiles, papers and composites. This technology is embodied in an expanding series of machine configurations known as Micrex/Microcrepers which allows companies to dramatically expand the use and application for traditional as well as new sheet materials.

Richard Walton, Micrex’s president said, “We now take existing nonwoven substrates with thermoplastic fibers in it, for example polyester or polypropylene, and by Microcreping under a unique set of conditions—give it stretch. We are giving people low cost stretch for garment interlinings, automobile headliners, and bandages to name a few applications. For example what you want in a bandage is to conform. If you bend your elbow, it will stretch, but not completely recover. It will ‘give.’ There are a wide variety of medical applications where things need to conform to the body. It’s a huge market. In medical, Microcreping could be useful in emergency room surgical gowns, surgical drapes and bandages. Stretch is expensive. The fact that you can put in something cheaper and have the characteristics of something more expensive is a big advantage. When you can do it using an off the shelf nonwoven and match those characteristics it’s a tremendous cost savings. We can take an industry standard spunlace and using these techniques give it extensibility in both the machine direction and the cross machine direction. We also look to apply this technology toward specialty applications with higher value added features such as filter media, batteries, electrical insulation, and building products.”