Makrolon makes sweet music: Baykomm - Bayer Communication Center

Special Story

Makrolon makes sweet music!

Although it has a diameter of only twelve centimeters and weighs only 18 grams, it's still an object of "heavy" demand. It owes its existence to a plastic that also makes a lot of other things in our daily lives much easier: Makrolon from Bayer. About 20 years ago, Philips used Makrolon to make the first version of an amazing data storage medium that soon went on to conquer the entire world: the Compact Disk, or CD for short. The 20 billionth shiny disk made of Makrolon recently came off the production line.

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If all these CDs were lined up next to one another, they would form a chain of silver roughly 2,400,000 kilometers long. That's more than six times the distance from the Earth to the moon. The volume of data that could be stored on them is even more amazing: a total of about 14 billion gigabytes! That's roughly the memory of all the home PCs in 136,000 small cities! The dimensions in which information is stored on a CD are also mind–boggling: about four billion recesses or pits, each measuring about one ten–thousandth of a millimeter! To give an idea of these dimensions, if a CD were as large as St. Peter's Square in Rome, one pit would correspond to a hole in the Square the size of a pin head!

Thanks in particular to the flowability of the Makrolon grade used, it takes less than four seconds to impress these delicate structures on a CD blank with high precision by injection molding. However, being a true "jack of all trades" among engineering plastics, the polycarbonate also offers a whole bunch of other advantages, which don't just pay off in the manufacture of CDs, but have also set this material up for an absolutely unstoppable career. Today, its primary fields of application include information and lighting technology, optics, glazing, electrical/electronic engineering, the transportation sector, medical technology, the home, the security sector and many more.

Clearing up a misconception: The birth of Makrolon
In the beginning, it was primarily a misconception that slowed the rise of this multitalented plastic. Generations of chemistry students learned in college that carbonates are thermally unstable and readily decomposable. So why even try polycarbonates at all? The 37 year-old Bayer chemist Dr. Hermann Schnell was unimpressed by this prejudice as he worked in his Uerdingen laboratory in 1953. He sifted through the literature. "To my great surprise, I found that no work had been done at all in this area for almost 50 years", he later explained. Schnell then did something that characterizes a "true" scientist: he decided to put his trust in experiments alone. When he reacted bisphenol A and phosgene, the two building blocks of Makrolon, he instantly came up with a material that the plastics industry had been looking for for years: a transparent polyester that was dimensionally stable at high temperatures but still thermoplastic (i.e. moldable by applying heat).

The end of life of the memory disk is the beginning of the plastic. Bayer has already taken back 5,000 tons from more than 350 million out of date CDs and has finished them to recyclate types.

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The end of life of the memory disk is the beginning of the plastic. Bayer has already taken back 5,000 tons from more than 350 million out of date CDs and has finished them to recyclate types.

Makrolon was a real gem. Its strength over bulk plastics, such aspolyethylene, polystyrene or polyvinyl chloride (PVC), was and is its combination of numerous favorable properties. For example, it remains tough and resilient at minus 100 °C. Parts made of Makrolon are dimensionally stable up to roughly 140 °C. The plastic does not soften until it reaches 150 °C and burns only when heated to over 500 °C. It is non-toxic, can be pigmented in any color and is odorless. It acts as an insulator for electricity and heat and is also recyclable!

Mega and giga - the Makrolon DVD
The CD now has an impressive partner in the Digital Versatile Disk, or DVD for short. Although you can hardly tell it from a CD on the outside, it has seven times the memory capacity (4.7 gigabytes). That's equivalent to the volume of data in a movie lasting 135 minutes with five dubbed languages or 1.7 million typed sheets of paper. If you take a closer look, you'll see that a DVD is made up of two, 0.6 mm-thick disks that are bonded together. The pits are four times smaller than those on a CD. Reproducing these pits precisely with the help of a metal stamper was a real challenge for Bayer's plastics experts. They finally reached a solution by using a special, improved grade of Makrolon.