Industrial-Boot Outsoles Injection Molded from New Vinyl Compound Resist Attack from Oils, Fats, and Chemicals

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RACINE, WISCONSIN, U.S.A., February 29, 2000--The harshest punishment endured by industrial apparel takes place where the boot hits the floor, and working conditions for outsoles are particularly hostile in chemical and food processing plants. These are the environments for which LaCrosse Rainfair, Inc. has developed a new series of boots whose outsoles provide rubber-like durability, comfort, and traction while retaining the manufacturing advantages of injection molded vinyl.

A leading producer of protective footwear and clothing, LaCrosse Rainfair designed an innovative "dual-density" outsole that employs two custom formulations of Flexalloy [trade mark] OR compound, a vinyl/elastomer blend from Teknor Apex that combines toughness and elasticity with outstanding resistance to chemicals and to fats and oils like those in poultry and meat processing plants.

LaCrosse Rainfair fuses the outsole directly to the soft, blue upper of its Flex3 [registered trade mark] boot in a two-stage process. First it over-molds the bottom of the upper with an orange-colored Flexalloy OR compound whose softness and flexibility cushions the foot and provides a gripping action to prevent slipping, according to Mike Quill, Senior Marketing Manager. A second over-molding step fuses a higher-durometer gray compound around the exterior of the orange segment. Protruding slightly more than the harder gray portion of the outsole, the softer orange segment contacts the floor, providing cushion and stability.

"What sets the Flexalloy compounds apart from materials used in our other injection molded outsoles is their outstanding oil-resistance," Quill said. "This property is doubly valuable in
the Flex3 boot since, by over-molding the outsole directly onto the upper, we eliminate the need for adhesives, which could degrade under aggressive attack and cause total product failure."

Noting that LaCrosse Rainfair has used vinyl materials from Teknor Apex for ten years, Quill said that his company specified Flexalloy OR compounds because they combine two of the latest advances in vinyl technology.

"To offer a wide selection of high-performance alternatives to our premium-priced rubber boots, we employ many different specialty vinyl compounds that outperform the standard vinyl formulations used for low-end boots," Quill said. "Recently we have employed compounds based on ultra-high molecular weight (UHMW) PVC polymer because they are stronger, more abrasion-resistant, and more elastic than those made from conventional PVC--even the specialty formulations. The advent of Flexalloy OR compounds, which are also UHMW-PVC-based, takes this progression a step further by adding superior oil-resistance to the property profile."

Besides the Flex3 boots, LaCrosse Rainfair uses the lower-durometer orange Flexalloy OR compound for the outsoles of its SureFlex [registered trade mark] product line.

When LaCrosse Rainfair subjected boots made from Flexalloy OR to prolonged exposure to animal fats, the boots were free of the stiffening and cracking exhibited by boots produced from conventional vinyl formulations, according to Quill.

"Until now, the only injection-moldable materials that combined this level of oil resistance with rubber-like strength and elasticity were thermoplastic elastomers (TPEs) costing 25 to 50% more than Flexalloy OR compounds," said John E. Macaluso, Industry Manager for Teknor Apex. "At the same time, the lower-cost, conventional TPE and flexible vinyl compounds that are widely used in footwear typically swell, shrink, or even completely disintegrate after prolonged exposure to oils."

Macaluso cited tests results comparing samples molded from Flexalloy OR compounds and the conventional materials mentioned above, after three days of immersion at a
temperature of 125 °C., in these aggressive fluids:

· ASTM #3 oil. Samples of Flexalloy OR compound swelled 0.9%, versus 15% swelling of a styrenic TPE (SEBS), 4.1% shrinkage of flexible vinyl, and disintegration of a thermoplastic polyolefin (TPO) elastomer. In the same test, Flexalloy OR-based samples retained 74% of their original elongation, a property that correlates with elasticity, versus only 1% for flexible vinyl.

· Lard. The Flexalloy OR-based sample shrank 5% in this animal fat, compared with 6% and 84% swelling of the SEBS and TPO, respectively, and 13% shrinkage of the flexible vinyl. The Flexalloy OR-base samples retained 84% of their elongation, versus 58% for flexible vinyl.

Macaluso coordinated the Teknor Apex program to develop custom formulations of Flexalloy OR compounds especially for LaCrosse Rainfair's new outsoles. "Teknor Apex technical service personnel worked closely with our design and manufacturing staff and the Teknor Apex product development laboratory to optimize the flow properties of both injection molding compounds," Mike Quill said.

LaCrosse-Rainfair Safety Products Division is located at 3600 S. Memorial Drive, Rancine, Wisconsin 53403, U.S.A. Tel: 1-414-554-7000. Fax: 1-414-554-6619. Visit their website at www.lacrosserainfair.com.