Phthalide derivatives and recording system utilizing the same
申请人:KANZAKI PAPER MANUFACTURING CO., LTD
公开号:EP0209259A2
公开(公告)日:1987-01-21
A new phthalide derivative useful as a colorless chromogenic material has the following formula:
wherein R1, R2, R3, R4, R5 and R6 have the same meaning as defined hereinbefore