| 摘要 |
A photochromatic composition contains at least two photochromatic compounds, defined by the general formula: <IMAGE> wherein the various substituents from R1 to R7 and X are as defined in the specification. In such a mixture, at least one photochromatic compound is defined by the general formula, wherein R7 represents a hydrogen atom, and at least one further compound is also defined by the general formula, wherein R7 represents an -NR8R9, with R8 and R9 having the meaning as defined in the text.
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