In September 2003, Sanyo Electric introduced the concept of a new optical disc, dubbed 'MildDisc' and based on poly lactid acid produced from corn. These discs will have a lifetime of 50 to 100 years and are biodegradable. At that time Sanyo anticipated that mass production would start in the first half of 2004. But now, IDG News Service reports that these corn-based CDs are delayed. These discs would not work correctly when facing a heat of 50°C. So Sanyo is refining the technology and says it doesn't know when the corny discs come to market.
Here is a description of the manufacturing process.
Production of the plastic used in the MildDisc begins with Cargill Dow in the U.S. It mills kernels of corn to separate out the starch and then processes these to get unrefined dextrose. Using a fermentation process similar to that of beer production, the dextrose is converted into lactic acid, according to the company's Web site.
Sanyo converts the lactic acid into a polymer used in the disc substrate using a method developed with Japan's Mitsui Chemicals.
In a somewhat childish way, the illustration below shows how corn will be used to make CDs (Credit: Link at Sanyo).
So what went wrong?
The disc, dubbed "MildDisc" by Sanyo, was to have been offered to customers from December last year and volume production was due to begin in the first half of this year but this has been delayed while Sanyo refines the technology, says Ryan Watson, a spokesperson for the Osaka-based company.
"There was a concern that if the disc was exposed to heat greater than 50 degrees Celsius that it wouldn't work properly," says Watson. "A timely topic now as the heat is blazing down on Tokyo, so the main obstacle that they are working on now is trying to improve the disc's resistance to heat. They can easily improve its resistance to heat with a mix of material but that kind of defeats the purpose of the MildDisc."
Sanyo doesn't know when these new dics are able to face the heat.
In the mean time, here are interesting numbers. Sanyo said that an ear of corn would be enough to deliver 10 discs. There are about 9 billions of CDs produced annually, and the yearly world corn production is estimated to be around 600 million tons. So only 0.1 percent of the world corn's production would be enough to satisfy the worldwide disc market, according to the company.
Sources: Martyn Williams, IDG News Service, July 12, 2004; Sanyo website