History (1993): Mitsui Stops Manufacturing M-O Media

Mitsui Petrochemical Industries Ltd. of Japan will stop manufacturing and selling magneto-optical disks this year.

At the beginning of the year, Optical Storage Corp. (Tokyo, Japan), an optical disk joint-venture set up in 1990 between Sumimoto Chemical, Sumimoto Metal Mining and Daicel Chemical Industries, was also closing down. This ceasing is even more unexpected as the M-O disk market is now seriously taking off.

Did these Japanese companies have manufacturing problems or did they give up in front of a too large competition? In 1991, Maxoptix (San Jose, CA) had precisely chosen Mitsui and OSC to manufacture cartridges for its 5.25-inch optical drives, and have to turn to other media manufacturers. Mitsui Petrochemical started making 3.5 and 5.25 M-O disks in 1988. Two years later, the company announced its intention to spend close to ¥3 billion to build a 3.5-inch M-O disk plant in Sodegura (Chiha Prefecture). The Lightstore media from the chemical firm was based on a proprietary cyclo-olefinic polymer APO.

This article is an abstract of news published on the former paper version of Computer Data Storage Newsletter on issue 65, published on June 1993.