| 摘要 |
Naphthalocyanine compounds represented by the general formula <IMAGE> wherein R1, R2, R3 and R4, which may be the same or different, are each a straight chain or branched chain alkyl group of 5 to 12 carbon atoms and M is a metal selected from the group consisting of Cu, Ni, Mg, Pb, Pd, V, Co, Nb, Al, Sn, In, Fe and Ge, or its oxide, chloride or bromide, are bluish green or green crystals and are superior in absorption of near infrared rays of 750 to 850 nm, highly resistant to light, heat, acids and alkalis, soluble in organic acids, liquid crystals and resins, and accordingly are very useful as a dyestuff capable of absorbing near infrared rays.
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