Santoprene still growing after 40 years

HOUSTON—Forty years after its introduction, Santoprene thermoplastic vulcanizate is growing faster than ever, claiming about 45 percent of the world's TPV market.

There are many reasons for this, according to Kurt Aerts, vice president, Specialty Elastomers & Butyl Polymers, ExxonMobil Chemical, and Mike Bednarik, Asia-Pacific technology adviser for ExxonMobil Chemical.

These include continuing major investments in capacity, research and development; a constant search for growth markets and new applications; and a total commitment to collaborating with customers to obtain the best quality and most appropriate applications possible, Aerts said.

"We are the undisputed industry leader," Aerts said. "ExxonMobil offers its customers supply security, product integration and on-time delivery. We follow new trends in the automotive industry, including electric vehicles. We put our knowledge together, using fundamental science in a way that allows us to collaborate with customers throughout our value chain.

"That's why we have a strong brand name," he said. "We do those things well every day, every minute, and therefore we have earned the right to be the preferred supplier and development partner in the marketplace."

Early beginnings

Santoprene TPV was developed in the course of researching a new polymer for tires, according to ExxonMobil.

It turned out to be unsuitable for tires, but it offered a multiplicity of other applications, ranging from tools to appliances to automobiles, the company said. The idea behind Santoprene was simple but revolutionary: It describes it as a material that had all the properties of a rubber, but could be processed like a thermoplastic.

Compared with thermoset rubber, Santoprene from the beginning offered better part performance, faster production cycle times, lower weight, lower production costs, greater design flexibility and greater opportunities for companies to meet their sustainability requirements, ExxonMobil said.

Between 1991 and 2002, Santoprene was a product of Advanced Elastomer Systems L.P. At the beginning, AES was the joint venture of ExxonMobil, then known at Exxon Chemical Co., and Monsanto Chemical Co. When Solutia Inc. spun off from Monsanto in 1997, it took Monsanto's 50 percent stake in AES with it.

Early in 2002, ExxonMobil bought out Solutia and became the sole owner of AES, folding the operation back into the main company.

Since becoming sole maker of Santoprene, ExxonMobil has retained all that was good about the joint venture, especially its close relations with customers at all points of the value chain, according to Aerts.

But taking over AES allowed ExxonMobil to strengthen Santoprene, he said.

"The raw materials we produced ourselves enhanced supply security," Aerts said. "Taking over AES broadened our capacity, our global footprint and our application expertise."

ExxonMobil manufactures both conventional and metallocene EPDM as well as Santoprene, according to Aerts. However, the company sees the three products as complementary, and not in competition with each other.

"Having all three in our product line gives us a lot more levers to create your products," he said. "We are not pitting them against each other. Having conventional EPDM, metallocene EPDM and Santoprene in our portfolio allows us to produce a greater array of materials to address our customers' needs."

Automotive presence

When ExxonMobil first introduced Santoprene, its customers had some confusion about it, according to Bednarik.

"We would go to rubber companies, but they didn't want to invest in new processing equipment," Bednarik said. "Plastics companies were interested in expanding their product lines, but didn't know who to sell them to."

Eventually these qualms were dispelled as rubber companies discovered that Santoprene could be processed less expensively than thermoset rubber and plastic companies discovered new customers.

Santoprene has enthusiastic customers in the appliance industry, especially companies such as Frigidaire, Whirlpool and General Electric, which have used Santoprene in dishwasher and refrigerator seals since the mid-1980s.

From the beginning, however, its biggest market always has been in the automotive industry. Today, according to Bednarik, auto makers account for more than half of all Santoprene sales.

Toyota was one of the first auto makers to use Santoprene extensively, but now the material is used widely by OEMs around the world, according to ExxonMobil.

Santoprene was widely adopted for rack and pinion boots in the early 1980s because it reduced costs while improving flex life, fluid resistance and sealability, the company said. Now, more than 90 percent of all cars on the road have Santoprene rack and pinion boots, it said.

Automotive applications have multiplied over the years, according to Bednarik. An abbreviated list of auto parts made with Santoprene includes weatherseal systems, seals for fixed windows, belt line seals, clear air ducts, rocker panels, heating and cooling hoses, struts and mounts.

Santoprene offers ease of processing, and is 20-30 percent lighter than EPDM, according to Bednarik. The material's versatility allows reconfiguration of parts. "One part now does the role of two or three parts," he said.

According to ExxonMobil, Santoprene also can help auto makers meet their sustainability commitments. Besides Santoprene's lighter weight compared with other materials, it can reduce waste by as much as 50 percent in weatherseal production, the company said.

Because Santoprene does not require heat curing, it also cuts weatherseal production costs by up to 25 percent, it said.

ExxonMobil is expanding these benefits to the auto industry with the introduction of new Santoprene grades, beginning with micro-foaming grades, according to the company.

"Moving from a dense rubber profile to a foamed TPV profile allows the extrusion of profiles that are much lighter and use less material than thermoset rubber alternatives," it said.

The micro-foaming grades reduce the weight of Santoprene by a further 20-25 percent, according to Bednarik.

Constant growth

Santoprene's growth rate is well above that of Gross Domestic Product growth in most of the countries where it is sold, ranging between 2.5 and 3.5 percent annually, according to Aerts.

ExxonMobil produces Santoprene at facilities in Pensacola, Fla., and Newport, Wales. By the end of 2017, it will complete an expansion at Newport that will increase global Santoprene capacity by 25 percent, according to the company. Product will be available in 2018, it said.

Aerts declined to reveal the amount of money ExxonMobil is investing at Newport. However, he did say that once the expansion there is completed, global capacity for Santoprene will stand at roughly 200,000 metric tons annually.

The Santoprene plant in Pensacola was not affected by Hurricane Irma, according to Aerts. Nevertheless, the hurricane points out the need to have more than one production site for Santoprene, he said. "It's important not to have all our eggs in one basket."

While Santoprene use continues to grow around the world, its most rapid expansion over the last 10 to 20 years has been in the Chinese automotive industry, according to ExxonMobil.

A growing Chinese middle class, along with more stringent fuel economy and environmental standards in China, is causing Chinese auto makers to both order more Santoprene and specify it more often in automotive applications, the company said.

Growing demand in China and the rest of Asia is behind ExxonMobil's current expansion of its Shanghai Technology Center, the company said. The STC will include a new "customer collaboration center" when it is completed in early 2018, it said.

ExxonMobil is adding space, equipment and applications development personnel at the STC, according to Bednarik.

"We'll be working with new materials, and how customers can use them," he said. "There will be an awful lot of education for our customers. The STC will serve all of China, and not just China. Shanghai is very close to the center of Asia."

The TPV market is very fragmented, and competition has made advances over the years, but Santoprene's position as the dominant player in the market remains constant, according to Aerts. But while ExxonMobil will have much more capacity in Santoprene in 2018, the company doesn't take its market position for granted, he said.

"Standing still is falling behind," Aerts said. "Competition is good for us, because it pushes us to stay ahead of the others."