Patents Assigned to Tokuyama Soda Kabishiki Kaisha
  • Patent number: 5246989
    Abstract: A photochromic compound of the present invention is a spiroxazine compound represented by the following formula: ##STR1## wherein R.sup.1 to R.sup.3 represent a monovalent organic group such as alkyl group, Y represents a fused heterocyclic aromatic hydrocarbon group or an unsaturated heterocyclic group if R.sup.1 and R.sup.2 are both methyl groups, and represents an aromatic hydrocarbon group or unsaturated heterocyclic group if R.sup.1 and R.sup.2 are other than the above mentioned. This compound shows an excellent photochromic characteristics even at high temperatures not less than ambient temperature.
    Type: Grant
    Filed: March 28, 1991
    Date of Patent: September 21, 1993
    Assignee: Tokuyama Soda Kabishiki Kaisha
    Inventors: Kayo Iwamoto, Takashi Tanaka, Satoshi Imura, Seiji Okazaki, Shinsuke Tanaka