Unique Glove Design Relies On Stevens Urethane Air Bladder To Dissipate Vibration And Impact

Air bladder minimizes health risks from impact, vibration, and repetitive motion

Belleville, Ontario, Canada — A new style of work glove introduced by Impacto™ Protective Products, Inc. relies on a unique air bladder system made with Stevens Urethane thermoplastic polyurethane (TPU) to protect workers from impact, vibration and repetitive motion injuries. Impacto AirGlove™ incorporates a patented AntiVib™ air bladder developed by ErgoAir, Inc., Las Vegas, Nevada, which absorbs and dissipates vibrations at both high and low frequencies, protecting workers who frequently use pneumatic drills, jackhammers, and other power tools. The gloves meet European standards for impact and vibration, and anticipated ergonomic standards proposed by OSHA.

Regular exposure to vibration can cause serious medical problems, such as a condition called “white fingers,” a breakdown of the nervous system where the fingers blanch and sensation is lost in the hand and fingers. Vibration has also been shown to cause or contribute to other hand/wrist medical problems such as carpal tunnel syndrome.

The AntiVib™ air bladder used in the glove was developed by Dr. Douglas Reynolds, Ph.D., and Dr. Thomas Jetzer, M.D, M.P.H., founders of ErgoAir. Dr. Reynolds, president, is a leading authority on noise and vibration control. Dr. Jetzer is the medical director for the company, drawing on an extensive background in occupational medicine. ErgoAir worked with Dielectrics Industries, Chicopee, Massachusetts, and Impacto Protective Products, Inc., Belleville, Ontario, to transform the concept of a vibration-reducing bladder into a glove that would meet the requirements of ISO Standard 10819 to be classified as an antivibration glove. Dielectrics contributed expertise in air bladder technology and manufacturing, while Impacto was already an established supplier of industrial safety products.

After nearly four years in development, the resulting AirGlove passed three different antivibration tests: the Center for Mechanical & Environmental Systems Technology (CMEST) at the University of Nevada, Las Vegas, Nevada; testing for European CEN certification as an antivibration glove at Delta Acoustics & Vibration in Lyngby, Denmark; and at the Berufsgenossenschaftliches Institut fur Arbeitssicherheit (BIA) in Sankt Augustin, Germany, the European laboratory at which test procedures in ISO Standard 10819 were developed. To date, the AirGlove is the only antivibration glove that has been tested at BIA that has met the requirements of ISO Standard 10819 to be certified as an antivibration glove. The glove was introduced to the market in early 1998.

“When ErgoAir approached us with the concept of using a TPU air bladder to attenuate vibration, we were very interested in incorporating it into our gloves,” said Ed Lehtinen, president at Impacto. “The air provides better protection than traditional materials, and the TPU gives us a thinner product, lighter weight, with better flexibility. It is not only superior in terms of dissipating vibration, but it is also a more practical product from a usage standpoint.”

Traditional anti-vibration gloves were far from ideal. At issue were both the frequency range the gloves could dissipate, and their weight and practicality. Many such gloves use visco-elastic polymers which are bulky and uncomfortable to wear. In addition, most of these visco-elastic polymers are ineffective in reducing vibration to the hands. Thus, gloves made with these polymers gave workers little protection from vibration. With the TPU-based anti-vibration bladder system, the Air Glove™ effectively reduces vibration to the hands, it is nearly weightless, and it is comfortable to wear.

"Visco-elastic polymers were initially the best materials available, but we've been looking hard for alternatives," noted Lehtinen. "The air bladder system represents a significant improvement in performance and comfort for the user. It attenuates both high and low frequencies, and weighs a few ounces at most."

"AirGloves dissipate between 40 and 60% of vibration depending upon the frequencies," said Ergo Air's Dr. Tom Jetzer. "You are not totally eliminating vibration. However, you are prolonging the time a person can use a tool without causing a medical problem."

With a strong background in air bladder technology, Dielectrics played a crucial role in developing the AntiVib bladder that was designed by Dr. Reynolds, including material selection. According to Steve Wiater, project manager at Dielectrics, TPU was chosen for its strength, flexibility, and temperature resistance. Materials like PVC did not offer the combination of properties required for the application. They would also have to be twice as thick to provide the same performance as the 6-mil TPU, detracting from the glove’s comfort and tactile properties. Stevens Urethane was specified for its quality and consistency, and because Dielectrics knew they could rely on the company’s service and technical support.

"We needed a material that could withstand extreme temperature ranges and take a lot of vibration over a long period of time," said Wiater. "Also, tensile strength was important. We wanted a very thin material, so the bladder would be streamlined and comfortable, not bulky. Given these criteria, TPU was the best choice to meet all our needs. We are able to use a very thin film, only 6 or 7 mil (.006-.007 inches), yet still be very strong. Other materials would have to be twice as thick to provide the same performance." Wiater notes that the pump in the air bladder provides about 10-12 psi pressure, and the TPU burst strength falls well within that range. "We selected Stevens as our supplier because of their service and technical back up," he continued. "We've worked with them before, and their ability to produce quick turnaround for custom samples is a tremendous help.

The AirGlove's AntiVib bladder system consists of a flexible hand-shaped bladder made from 6 mil Stevens Urethane, die cut and radio-frequency (RF) sealed. The bladder is designed with a quilted pattern of weld points and weld lines corresponding to the flex lines of the hand. The bladder is constructed with interconnected chambers, which, when a tool or other object is gripped, allows the pressure to force air out of the slightly thicker palm and into the finger chambers, for consistent thickness and protection throughout the glove.

The bladder includes a pump and valve system which allows the user to inflate the bladder by depressing a bulb on the back of the glove. Some 50-60 pumps are needed to fully inflate the bladder for maximum protection, with daily touch-up pumps to replenish air lost through osmosis or slow leakage through the valve. Correct inflation is critical, because if air is lost and not replaced, protection is reduced accordingly.

"Flexibility makes the glove comfortable and practical, so it is easy to get a good grip. A strong material like Stevens Urethane means the bladder can be thinner, yet still provide the protection and burst strength we need," said Lehtinen. "Durability is another issue because the product has to last. In addition, the bladder must withstand continuous vibration, temperature fluctuation and heat generated by tool and hand, and to a lesser degree abrasion. Although the leather glove protects the bladder and provides grip, the bladder must still be tough."

Impacto's newest product is a glove liner, where the bladder is incorporated into a fabric glove which can be worn under any other kind of glove, leather, cotton or even a rubber disposable glove, depending upon the environment. The outer glove is replaced as needed, while the more expensive bladder liner is used over and over.

"Thickness, weight and flexibility are even more important here because now the user is wearing two gloves, the liner and the outer glove," noted Lehtinen. "The liner makes a lot of sense. People use the gloves they have and buy more when they wear out, rather than replacing the whole glove/bladder system. The liners will last through many sets of gloves."

"The lightness and flexibility of TPU are key to the performance of the bladder," added Dr. Reynolds of Ergo Air. "It is so thin that it's almost not there, which makes it more comfortable to the wearer. It creates a cushion with no interference with the tactile feel in the glove."

Stevens Urethane is a recognized leader in the design and manufacture of polyurethane film, sheet, and tubing, sold under the Stevens brand name. Stevens Urethane offers a family of urethanes ideal for "can't fail" medical applications. Stevens film and sheet can be manufactured in thicknesses from .001" to .125" and in widths from 5 inches. Tensile strength up to 10,000 psi assures reliability and durability over a long working life, and urethane film and sheet can elongate significantly and still return to its original dimension with no loss of "memory." Stevens Urethane is available in hardnesses from 75 to 95 Shore A, and in a range of standard and custom colors. Various opacities and surface textures are also available. It can be custom formulated to meet specific application requirements.

Based in Easthampton, Mass., Stevens Urethane manufactures a full range of high-performance urethanes for use in a wide variety of "can't fail" applications for consumer, medical, commercial, and industrial markets. Stevens Urethane is the only company in the world to offer urethane in blown film, extruded sheet, tubing, cord, and profile form.

For additional information, contact: Stevens Urethane, 412 Main Street, Easthampton, MA 01027. Phone: (413) 533-8100, or toll free at 1-877-TPU-FILM (1-877-878-3456). FAX: (413) 552-1195. E-mail: info@stvure.com. Stevens Urethane is a business unit of JPS Elastomerics.

Contact Impacto Protective Products Inc. at (613) 966-0062, toll free at (888) 232-0031 or www.2protect.com. Contact ErgoAir, Inc. at 1-702-454-1478 or www.ergoair-inc.com. Contact Dielectrics Industries at 1-800-472-7286 or www.dielectrics.com.

Impacto and AirGlove are trademarks of Impacto Protective Products, Inc.