Some inventions point to the future, and the discovery made by Bayer chemist Dr. Hermann Schnell 50 years ago was certainly one of them. He used bisphenol A, the condensation product of phenol and acetone that had been known for some time, together with phosgene to produce a polycarbonic acid ester that displayed unexpectedly good properties as a plastic. Schnell’s invention was patented on October 17, 1953 and later went into production, initially in the form of very thin, but extremely tear-resistant Makrofol® film, which, among other things, was used by Agfa to manufacture photographic films.

Five-gallon Makrolon® water bottles manufactured by the Capsnap company in the United Kingdom undergo a visual check.

Five years later, the new plastic, now known as Makrolon®, proceeded to take the world by storm like no product had before. This was not surprising, because the Bayer material is characterized by properties that only a high-grade polycarbonate can offer: Makrolon® is virtually unbreakable, light and impact-resistant, even at extremely low temperatures; it is easily molded, but displays exemplary heat resistance. Most important of all, Makrolon® is as clear and transparent as glass.
 
Its wide range of properties enabled the Bayer polycarbonate to find applications in numerous spheres of everyday life. In the 1960s and 1970s alone, Bayer steadily expanded the Makrolon® product range to over sixty grades and more than 500 color shades. One prominent example of its use is the roof of Cologne’s central train station, which was renovated in 1985 using 13,500 square meters of Makrolon® sheet to replace the old glass roof.

Makrolon® sheets for high-quality roofing manufactured on an extruder line at the Makroform company in Tielt, Belgium are subjected to stringent quality control.

Compact discs: one in three is made of Makrolon®
One innovative application that went into mass production in mid-1982 was the Makrolon® CD. This invention was the result of several years of research work at Bayer, Philips and Sony. It required the development of a completely new opto-electronic storage method, and a modern laser system that scanned the stored digital data in contactless fashion, i.e. optically. However, the development of the substrate material for the revolutionary data carrier was equally important. It was here that Bayer scientists did pioneering work – and, together with the experts from the PolyGram record company, recognized that Makrolon® was the ideal answer to the stringent demands imposed on the material for this new form of sound-recording medium. Following its development, more than 100 billion CDs were manufactured worldwide by 2001 – one in three using the Bayer polycarbonate.
 
To play music from a CD, a laser has to scan a microscopically small pattern of bumps and grooves that contains the stored data. The storage capacity of one CD comprises roughly five billion of these pits. As on a conventional record, the pits are arranged in a spiral-shaped track. The distance between the roughly 20,000 turns of this track is just 1.6 micrometers, which allows a vast quantity of data to be accommodated on a 12-centimeter disc.

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