From chain molecules to high-tech material: 100 years of synthetic rubber

In 2009, synthetic rubber will be 100 years old - a date that is not just significant for the history of chemistry but also for technology in general, and it is still relevant to this day. Synthetic rubber was invented by chemist Fritz Hofmann, at that time employed at Elberfelder Farbenfabriken Friedr. Bayer & Co., a company whose legacy is continued today by specialty chemicals group LANXESS AG. Patent No. 250690 for the first "process for manufacturing artificial rubber" was granted on September 12, 1909. For Hofmann's successors - right down to present-day rubber chemists at LANXESS - the synthetic rubber inventor's reputation has always been both an incentive and a benchmark that they strive to live up to. From the outset, they have been heavily involved in the further development of the material. LANXESS rubber innovations continue to ensure that rubber remains successful in challenging technical applications amid ever greater demands on elastic materials. Synthetic rubber innovations of LANXESS will be an important thing also in the future. "Strictly speaking, there is not just one form of synthetic rubber," says Guenther Weymans, head of the Technical Rubber Products business unit at LANXESS, one of three sectors of the company providing high-performance rubbers for the tire and rubber sector and playing a major role in the group's success. "Today, the engineering world can call on a whole family of chemically customized elastomers whose properties can be closely adapted to a range of applications," adds Weymans. "The pioneering work of Fritz Hofmann showed experts at the time that rubbers could indeed be manufactured synthetically." Until Hofmann's discovery, industry was forced to rely on plantation rubber, which was subject to considerable fluctuations in price and quality and, above all, allowed very little chemical modification and could not therefore be adapted to the increasingly demanding needs of technology. Real success for synthetic rubber came when further discoveries had been made, many of which involved researchers of the predecessors of LANXESS. Years after Hofmann's discovery, another chemical building block was transformed into a rubber raw material by using sodium. Afterwards things went from strength to strength, with chemists Walter Bock and Eduard Tschunkur refining the new basic formulation in a laboratory of the former I.G. Farben company and deriving from it a new, highly robust synthetic rubber - styrene rubber Buna S - that is still in use in an evolved form today. The patent for Bock's butadiene-styrene copolymerization was granted on June 21, 1929. Styrene rubber today is a widespread rubber raw material for tire manufacturing. The name Buna contains the initial letters from the required ingredients butadiene and sodium (Na). Oil-resistant nitrile rubber (Buna N, later Perbunan) is also based on a similar formulation and it too was invented in Leverkusen. "Without these and many other synthetic rubber grades, the world would look very different without the pioneering work of Hofmann," says Weymans. "After all, highly advanced mechanical engineering also relies on special-purpose rubbers that do not become brittle at high temperatures and can safely transport aggressive media under pressure. Natural rubber would fail in these applications after a very short period of time." A lot has therefore been accomplished since the invention of synthetic rubber. Today, the engineering world uses a multitude of special-purpose rubbers from the reactors of the chemical industry. For example, LANXESS has well over 100 different synthetic rubber grades in its range, including 60 different nitrile rubbers alone that are largely tailored to specific tasks and feature exotic rubber grades with an extremely abrasion-resistant, "paper-friendly" surface that are ideal for applications such as letter sorting machines. Other LANXESS high-performance rubbers such as Therban offer excellent mechanical strength at high operating temperatures. They ensure, for example, that toothed belts in cars need to be changed much less often than it was previously the case.