Plastics Are the Big Winner in Sports: Diverse polymers enhance performance and aesthetics of numerous applications.

The sports market is making greater use of advanced materials and designs to create equipment, stadium structures, and artificial playing surfaces that meet evolving performance, aesthetic, and environmental needs.

The market—which includes recreational gear—is big business. Potential customers range from professional and amateur athletes to children playing on organized and sandlot teams and individuals exercising for physical fitness. Inspiration comes from many sources—professional and collegiate sports, especially, and this year from the Summer Olympics (July 27–August 12) and Paralympics (August 29–September 9) in London.

In the U.S. alone, the sports industry in 2011 accounted for $422 billion of revenue, according to figures from Plunkett Research, Ltd., of Houston, Texas. While this number includes non-participatory expenditures such as ticket and clothing sales, Plunkett reports that retail equipment last year accounted for $40 billion of business. Wholesale equipment revenue generated $74.2 billion in 2010, the last year for which annual figures are available.

As in any market this big, numerous factors affect product development. Performance is key, of course, but equally important are aesthetics, weight reduction, ergonomics, cost, and, increasingly, environmental considerations. “We see more focus on the purity and carbon footprint of the materials we provide,” remarks Ewald Heersema, technical business and OEM manager at Zotefoams Inc., Walton, Kentucky, USA.

Sports manufacturers are specifyingmore sophisticated polymers. “OEMs are always looking for new materials,” says Jim Coleman, market development engineer for sporting goods at Ticona, Florence, Kentucky, USA. “They want to push boundaries with the next, best material.”

Many influences

Influences on the performance, appearance, and environmental engineering of sports equipment come from many markets. One is automotive, where bright colors have made inroads in recent years. This is reflected in equipment designs that feature eye-catching colors, and in materials that optimize paints, graphics, and other aesthetic features.

“Manufacturers want that extra pop in appearance that will hold a buyer’s attention for another 10 seconds” and possibly result in a sale, says Bob Shaw, B2B marketing communications manager for Ticona.

Another influence is fashion, which translates into stylish products—fabrics as well as equipment—that are durable and maintain their appearance, as well as providing performance.

Structural developments also affect equipment design. DSM of Heerlen, The Netherlands, for example, applied fabrication techniques learned from the use of its composite resin in wind turbine blades to design a 470-class (two-person) racing boat for the 2008 Beijing Summer Olympics, at which the Dutch women’s team won a silver medal. A DSM representative says that the company’s Turane thermoset polyester resin, reinforced with TexTreme carbon fiber from Oxeon of Sweden (U.S. office is in Spring Grove, Illinois), produced a craft with higher rigidity than competitive materials. This meant that the boat hull didn’t bend on impact with choppy seas, thus preserving energy and achieving greater speed.

The DSM representative adds that because Turane cures at room temperature, it requires less energy when used in fabricating a structure, reducing its carbon footprint and, also important, lowering manufacturing cost.

Meeting “green” needs

Other companies provide “green” benefits in their materials. Merquinsa, a supplier of thermoplastic polyurethanes (TPUs) based in Barcelona, Spain (U.S. office is in
Seabrook, New Hampshire), developed the Bio TPU line that includes Pearlthane ECO, which is based on polyols formulated from plants. Representative Lidia Valcarcel says that the renewable polyols have thermal, mechanical, and rheological
behaviors similar to those of petrochemical-based TPUs. They have been certified by Adidas, Brooks Sports, and other OEMs, and products with the materials will be in use at the London Olympics and Paralympics.

Merquinsa, acquired late last year by Lubrizol Corp. of Cleveland (Ohio, USA), another TPU specialist, also supplies the Pearlthane 91 series of aliphatic TPUs, which have hypoallergenic properties; lightfastness; UV stability; high resistance to
abrasion, scratching, and chemicals; and good flexibility and resilience.

Applications for both TPUs include footwear, goggles, and surface-protection films.

Another TPU supplier, BASF Corp. of Wyandotte, Michigan, USA, has successfully applied an in-mold material developed for the automotive market to recreational applications, in the process achieving benefits in aesthetics and performance.

The material is Elastoskin, a twocomponent, MDI (methane diisocyanate)-based TPU that competes with vacuum-formed or stitched polyvinyl chloride (PVC) for seat covers on all-terrain vehicles (ATVs), snowmobiles, motorcycles, and watercraft, as well as stadium seats and padding. Market development manager Steven Hicks says the material forms a one-piece foamed part in the mold that has high UV stability, contains no plasticizers, resists moisture penetration, and, if punctured or ripped, is easily repaired with an adhesive.

Hicks says that when a PVC surface is torn, the cover stock loses plasticizer and usually separates at the point of damage, exposing the foam underneath. (This is why PVC seats often have duct tape over damaged areas.) The Elastoskin PUR, in contrast, won’t separate away from a tear, which facilitates repair.

The molding process is straightforward: a mold release is applied to a clamshell mold, followed by a UVresistant coating. The Elastoskin is robotically sprayed on, generally to a thickness of 40 mils, after which a layer of flexible foam is applied. The skin is demolded and placed in a forming tool. Hicks says that mold textures can replicate stitching or other surface features.

Elastoskin was developed for instrument panels on Ford Explorer pickup trucks. It was then specified for the Polaris Ranger ATV, and has expanded into other sports and recreational areas. The material is less expensive to use than stitched vinyl, though more expensive than vacuumformed PVC.

TPEs enhance design

Thermoplastic elastomers (TPEs) play a major role in sports and recreational products. One reason is design flexibility. With a broad formulation range, durometer ratings from gel to semirigid, the ability to mold in structure-enhancing features such as ribs, and additive enhancements that improve properties, TPEs
offer potent material combinations for different performance needs. Add to this the ability to color TPEs and their generally lower cost compared with rubber and other competitive materials.

Teknor Apex of Pawtucket, Rhode Island, USA, demonstrates this formulation versatility with various grades, among them Monprene styrenic elastomers. At NPE, the company introduced the Monprene Wet Grip Series for injection molding that combines a nonslip surface and secure grip when wet with soft-touch properties. Brian Mulvaney, senior market manager for consumer and industrial products, says the grades will be targeted at golf clubs, bicycle grips, weightlifting gloves (sewn on as strips), and other applications that require a sure grip—or footing—on wet surfaces.

Wet-grip materials have been around for a while—most use tackifiers to increase the coefficient of friction when wet. New versions make use of other additives. Teknor’s wet-grip technology is proprietary, Mulvaney says.

Kraiburg TPE of Germany (U.S. office is in Duluth, Georgia) also has a new wetgrip
technology based on styrenic block copolymers that sales and marketing manager Keith Dunlap says relies on an additive developed primarily for a large consumer-goods OEM. Dunlap says the additive technology “increases the coefficient of friction without the negatives associated with conventional tackifiers.” These include attracting dirt, color-additive dissipation problems, blooming, and eventual
dissipation. The additive that Kraiburg developed disperses throughout the compound and doesn’t bloom, which means it essentially lasts for the life of the product.

The wet-grip TPE is branded Thermolast W. It won’t be possible to replace all tackifiers with the additive, Dunlap notes, “but we can get up to three times the grip when wet without tackifiers alone.” The material will be marketed for applications where wet traction is needed for grip. It is generally available—however, most applications require development to optimize the compound to meet specific needs. The technology is “ideally suited for sports and recreation products, along with kitchen utensils, safety equipment, water craft, and even surgical devices,” Dunlap says.

Improving performance

Engineering and reinforced thermoplastics have always found use in sports equipment. Recent innovations have produced grades that meet performance requirements in diverse applications.

One such is Hostaform HS15, an acetal copolymer (POM) from Ticona that has been molecularly enhanced to provide greater mechanical properties and better long-term stability and chemical resistance than most competitive POMs. Ticona’s Jim Coleman says the material is ideal for ski and snowboarding equipment, where its cold-temperature impact strength and stiffness deliver the durability necessary to withstand extremes in temperature and moisture.

Other applications benefit as well. A recent use for Hostaform HS15 comes from GenMove USA LLC, which developed a circular goal for children’s games that incorporates injection-molded sleeves, posts, and arms made of the material. The grade was specified for the product, called MultiGoal, for its ability to deliver robust performance and long life through enhanced stiffness, toughness, and resilience.

Ticona wants to extend its sports materials with Celstran continuous reinforced thermoplastic fiber tapes. Similar to its Celstran pultruded long-fiber-reinforced thermoplastics, the glass-fiber, carbon-fiber, or aramid-fiber unidirectional tapes are impregnated with various resins and used in products that require the strength, stiffness, and other properties such materials provide. The tapes are used in the BamBoo concept electric vehicle from Rinspeed Inc. of Switzerland; materials include a 70% glass/polypropylene tape; 60% glass Hostaform POM tape; and 60% carbon fiber/polyphenylene sulfide tape made with Ticona’s Fortron resin.

Fiber reinforcements also contribute to weight reduction. In high-end and professional equipment, this is as important as any performance feature. RTP Co. of Winona, Minnesota, USA, has developed fiber-reinforced and long-fiber-reinforced compounds that increase lightweighting and mechanical properties. “When it comes to reducing weight and boosting performance, fibers are great, especially carbon fibers,” says Eric Lee, business manager for structural materials.

Lee points to RTP’s success at developing carbon fiber-reinforced archery bows, which enable archers to release arrows with greater speed and range than with conventional bows, and its use of carbon fiber in bicycle components as small as a pedal, among other applications. Carbon fiber is ideal, he says, where athletes are acutely aware of performance and when “grams matter” in lightweighting equipment.

RTP helped Werner Paddles develop a durable, lightweight kayak paddle of nylon 6, which was reinforced with carbon fiber and modified with an appearance additive. The paddle compound contains glass spheres that displace the polymer and reduce weight. The technique has been used by RTP in automotive compounds.

Weight reduction is a specialty of Trexel Inc., of Wilmington, Massachusetts, USA. The company’s MuCell nitrogen-based or carbon dioxide–based microcellular foam process reduces weight and enhances mechanical properties of injectionmolded parts. The company has focused on automotive, but is expanding into energy-absorbing flexible-foam sports components.

One application is shoes. Vice president of engineering Levi Kishbaugh says that with MuCell, manufacturers can foam materials besides ethylenevinyl acetate (EVA) to reduce density and, importantly, to improve compression set. One example is TPU. Although MuCell-foamed TPU achieves less density reduction than crosslinked EVA foam—0.27 g/cc for TPU vs. 0.20 for EVA—Kishbaugh says there is a 50% improvement in compression set. In high-end athletic shoes, this equates to better energy management with less weight. “By improving energy absorption, shoe manufacturers can go to thinner constructions and offset the density difference,” he adds.

Since MuCell is an injection-molding process, Kishbaugh says, OEMs have a high degree of control over foam expansion and thus the shape, length, and weight of a shoe. New Balance is molding TPU with the MuCell process in a new line of highend
athletic shoes. Kishbaugh wants to apply the process to other energy-absorbing foams, such as those in shoulder pads and helmets.

Another producer of energyabsorbing material is Zotefoams. The company extrudes crosslinked, closed-cell foam sheets of low-density and high-density polyethylene (HDPE) and EVA. Foaming is with nitrogen, which, technical business and OEM manager Ewald Heersema says, eliminates outgassing and odor. The process also yields foams that he says are up to 25% less dense than other closed-cell processes—down to 1.8 lb/ft3 for HDPE.

Zotefoams’ sheets are fabricated in 2- by 1-meter (6.6- by 3.3-ft) sizes and 30-mm thicknesses. Key sports applications include hockey gear, notably the shot-blocking gloves worn by goalies. Zotefoams supplies HDPE foam for this application, which replaces the previous cushioning structure of PE and PUR, and reduces weight by 60%.

Since the company does not use a chemical blowing agent such as azodicarbonamide, Heersema says, it can foam a wider range of materials.
These include crosslinked HDPE, nylon 6, and polyvinylidene fluoride. The fluoropolymer foam, which has been certified for aviation, is expensive, but Heersema believes it could have applications in specialty sports equipment.

Marketing with color

Colorants, such as those from Clariant Masterbatches of Muttenz, Switzerland, are crucial to the appearance and marketing of sports-related products. For equipment, Jeff Saeger, global head of consumer goods, sees demand increasing not only for color but also for special effects such as pearlescents, as manufacturers seek to make products stand out. “In sports, 25%–30% of products target special effects,” he says. Clariant has ColorWorks design and technology centers that help OEMs develop colors for visual appeal.

One example he cites is work with Italian ski-boot producer Garmont, which developed the lightweight MasterLite boot made of Pebax polyether block amide from Arkema Inc., King of Prussia, Pennsylvania, USA. Clariant engineers used 3-D modeling in place of color chips to help the company select colors that convey lightness without detracting from the strength and performance of the product. Clariant then developed masterbatches of the color, which are used to differentiate several models in the MasterLite line. Ladies’ boots, for example, use lighter colors and pastels, while the men’s line tends toward more intense hues.

Clariant supplies additive masterbatches that can help enhance performance in applications as diverse as equipment and stadium seating. Saeger says seating products include durable, polyphosphate-based nonhalogenated flame-retardant grades that he expects will find use in the 2014 World Cup games in Brazil, and in the 2016 Summer Olympics and Paralympics in Rio de Janeiro. “Bids are going out now [for seats],” he remarks. “The World Cup and Olympics will together require one million new seats.”

Special effects extend to textiles. Clariant is partnering with Schoeller Technologies of Switzerland to provide Coldblack, a finish for dark-colored textiles that reduces heat absorption from the sun and keeps wearers cool and protected from UV radiation. Saeger says similar technologies could have applications in artificial turf, where it would reduce heat buildup on playing fields.

Clariant Additives, meanwhile, is promoting a backing for artificial turf that it says provides benefits in manufacturing, cost, and green engineering. Licocene is a metallocene-catalyzed hot-melt adhesive that is a recyclable alternative to latex and polyurethane (PUR), for backings on turf made of polyolefin or polyamide monofilaments and fibrillated yarns.

Christian Steib, technical marketing manager for Clariant Additives, says that applying Licocene backing instead of latex backings reduces process energy by 80%. Licocene runs faster than latex on coating lines—up to 12 meters (39 ft)/ minute vs. 3 to 4 meters/minute—because as a hotmelt it just needs to cool to set. Latex, Steib says, needs time to dry because the back-coating is a water-based emulsion containing fillers. Since Licocene is a hot-melt adhesive, there is no need to discharge or recycle waste water. Moreover, the thickness of a Licocene backing is typically one-third to one-half that of latex, which Steib says reduces the weight of turf rolls and lowers shipping costs and carbon footprint during transit. Lighter-weight rolls also mean easier handling and installation.

Plastics and building

Advanced polymers are a mainstay of stadium design and construction. Their light weight compared with traditional materials permits faster, more economical construction; their strength and ability to be fabricated in diverse shapes broadens the design potential of stadiums; and energyconserving properties, low carbon
footprint, and recyclability enhance green engineering.

A major supplier in this market is Sabic’s Innovative Plastics business of Pittsfield, Massachusetts, USA, whose Lexan polycarbonate sheet grades have been specified for more than 50 stadiums around the world. Thermoclear sheet is one grade that provides significant benefits over glass. It is a tough, multi-wall glazing material for use in roofs. Its light weight, formability, and impact resistance—250 times that of glass—resist extreme weather and vandalism. The multi-wall construction adds thermal insulation properties.

One Thermoclear sheet installation is in Slaski football stadium in Poland, where the glazing forms a freestanding roof. The sheets, as long as 12 meters, are 25 mm thick, weigh 5 kg/m2, and resist 5000 Newtons/m2 from wind or snow.

Another Lexan sheet grade is Thermoclick, a 9-wall glazing structure with V-joint connection profile that interconnects, eliminating the need for vertical profiles in construction, thus reducing installation cost and enhancing aesthetics. Thermoclick is a 1000-mm-wide, 50-mm-thick sheet with thermal insulation properties that reportedly reduce energy consumption up to 17% over double-pane glass. The grade has UV protection on the outer surface and comes in a range of colors.

At least one venue at the London Summer Olympics will feature an innovative building system from BASF. The Aquatic Center is using Elastopor SPS (steel/PUR/steel) panels to build cantilevered structures for 5000 permanent and 15,000 temporary seats.

Ernie Lee, business development specialist for BASF Canada in Mississauga, Ontario, says this construction technique, originally developed for ship decks, bridge repair, and civil construction, involves sandwiching a sheet of Elastopor PUR between two steel plates. The PUR bonds to the steel, and the steel in turn is welded to vertical risers for stability.

The technique has several benefits: The structure is 25%–40% lighter than pre-cast concrete; it shortens construction time by 15%; it facilitates disassembly; and the steel and PUR are recyclable. After the Olympics, in fact, the SPS panels erected for the 15,000 temporary seats will be removed.