100 years of synthetic rubber

Rubber has become an indispensable part of the modern world. Wherever machines or engines have to be provided with bearings, forces transferred, liquids transported and containers sealed, there s no getting around this material. In 1909, the chemist Fritz Hofmann succeeded in producing the elastic substance methyl-isoprene, and thus paved the way for the development of synthetic rubber. Hofmann conducted his research at the laboratories of Elberfelder Farbenfabriken vorm. Friedr. Bayer & Co. a company whose tradition is continued today by the specialty chemicals group LANXESS.

Without natural rubber combined with technology, it would be hard to come up with the latest rubber-based products of today. The technology and the requirements that rubber has to satisfy have been revolutionized since the early days when the first coats, boots, inkpots and even combs were made of (hard) vulcanized natural rubber.

State-of-the-art rubber goods are often made by mixing synthetic rubbers with a umber of other components, such as fillers, plasticizers and antioxidants. And this can only be done once the rubber's chain molecules have been crosslinked under pressure and at high temperatures in a process known as vulcanization. Before Hofmann invented synthetic rubber, the industry was limited to using natural rubber, a material obtained from plants that was subject to fluctuations in quality and price. It was practically impossible to modify its chemical structure, which meant it could not be adapted to meet the increasing demands of technology. As a result, Elberfelder Farbenfabriken offered a prize of 20,000 German marks for the person who could find a process for producing rubber or a suitable alternative by November 1, 1909. Not a lot was known about rubber back then. For example, it was not until 1905 that it was discovered that the chain molecules of this elastic material comprised countless strings of isoprene molecules, but no one knew how to crosslink
them. Nevertheless, Hofmann decided to give it a try.

As it was difficult to produce the natural rubber module isoprene, Hofmann quickly decided to use methyl-isoprene, which had a very similar chemical structure and was easier to manufacture. He placed the material in tins, heated them, and waited sometimes even for months. Depending on the temperature, the substance that formed in the tins was sometimes softer, sometimes harder, but it was always elastic. As it turned out, Hofmann had invented methyl rubber. The patent for the world's first synthetic rubber was awarded a hundred years ago on September 12, 1909. Continental a leading rubber company even then started to produce the first car tires from this new material as early as 1910. Hofmann's boss Carl Duisberg traveled 4,000 km on the tires without a puncture . Even the German Kaiser had his car fitted with the tires and was extremely pleased with the results.

Driving force in the rubber industry

Synthetic rubber became even more important as it was discovered how to form chain molecules from rubber modules, such as Hofmann's methyl-isoprene, more quickly and successfully than before. It was the addition of sodium that made this possible. In the 1920s, Hofmann's successors succeeded in using this metal and many process tricks to create another synthetic rubber from butadiene, a simpler chemical relation of the natural rubber module isoprene. This product went down in history as Buna a term coined from its constituents butadiene and sodium (Na).

The rubbers that chemists produced in the first third of the last century from the new starting material butadiene got better and better. The next step was taken a short time later by the chemists Walter Bock and Eduard Tschunkur. Bock in particular was responsible for combining butadiene with another highly promising module styrene. This gave rise to the styreHeel Shoes Boat Shoes