Next-Generation Products Make Better Shoes
In 2006, the world produced approximately 18 billion pairs of shoes, which is almost enough for three pairs per person. So far, the market has been dominated by rubber and thermoplastic materials like polyvinyl chloride (PVC). However, polyurethanes present a high-quality, versatile alternative to traditional materials.
“Polyurethanes could challenge traditional material,” says Andrea Benvenuti, senior development specialist for the Application Technology Development organization of The Dow Chemical Company (Dow). “We help our customers make better shoes.”
Comfort, Performance and Durability
Dow’s next generation of VORALAST™ Polyester Polyurethane Systems offer customers a material that is more durable, flexible and comfortable than rubber or thermoplastics. This means that shoe makers are able to produce better products for their customers.
“We are creating solutions that help our customers to succeed,” says Giuseppe Vairo, development specialist for Dow’s Application Technology Development organization. “When they win, we win.” One of the advantages polyurethanes offer over other materials is versatility. Different shoe styles require different types of soles. Work and safety boots need tough, strong soles that have good grip.
Other shoes, such as athletic shoes or sandals, require lighter materials with higher flexibility. VORALAST Polyurethane Systems provide solutions to a wide range of needs for Dow customers. VORALAST Systems can reach molded densities lower than 320 kg/m3.
“Polyurethanes are favored both for comfort and performance,” says Renato Paludetto, Global Footwear Application Technology Development leader for Dow Polyurethane Systems.
Shoes made with VORALAST Systems are also stronger and more durable than other materials. All systems have a load bearing of at least 30 to 35 N/cm2. This avoids problems of compression/load deflections during wear. “Soles made with this material will last longer,” Benvenuti says.
Great Looks, Lower Cost
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In addition to having a short curing time, VORALAST™ Polyurethane Systems also have a low freezing point, as well as a gentler melting point. Some prepolymers were able to stay liquid at temperatures as low as zero degrees Celsius. This means that VORALAST Systems are easier and cheaper to store and process. The low freezing point minimizes the risk of clogged mixing heads or machine filters. “Other materials may be cheaper, but our equipment is much, much less expensive,” Paludetto says.
Sustainable Product Mix
Dow has also developed VORALAST™ RS, a new family of renewable polyurethanes systems. VORALAST RS incorporates natural oil-based polyols (NOPs), which utilize less energy and emit fewer greenhouse gases during production. At the same time, the addition of NOPs maintains the high performance standards customers expect from Dow.
VORALAST™ RS maintains molded densities lower than 320 Kg/m3 (20 lbs/ft3), which makes it suitable for sandals, slippers and sport shoe midsoles.
The new generation of VORALAST systems also keeps their flex fatigue properties at temperatures as low as -20°C (-4°F). The excellent flow of the material allows for easy design copy, even when using complex specialized molds. VORALAST is highly productive, capable of producing up to 6,000 pairs per shift with a demolding time as low as 90 seconds when using the appropriate system. VORALAST is also chemical, oil and water resistant.
“The product performance is excellent for making shoes,” Benvenuti says.
By developing products in the VORALAST series, Dow has shown the ability to use its world-class technical abilities to develop innovative solutions for its customers. “We help our customers make better products,” Benvenuti says.
