| 摘要 |
PURPOSE: To enhance hue, coupling activity, and heat and light fastness, and thermal stability of a coupler itself and to reduce the fluctuation of color devel opment density by incorporating a specified coupler in at least one layer on a support. CONSTITUTION: At least one kind of coupler to be added into at least one layer on a support is represented by the formula in which Za is -C(R3 )= or -N=, and when Za is -N=, Zb is -C(R3 )=, and when Za is -C(R3 )=, Zb is -N=; each of R1 and R2 is an electron withdrawing group having a Hammett's substituent constantσp of 0.20-1.0; R3 is a substituent; each of R4 and R5 represents independently H atom or an aliphatic or aryl or heterocyclic group, or each may combine with each other to form a 5- or 6-membered ring, which is optionally condensed with a benzene ring or a hetero ring.
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