| 摘要 |
PURPOSE:To prepare a guest-host type liq. crystal display element which brings about no catalytic fading and has excellent light fastness, by dissolving a particular anthraquinone dye when at least two kinds of dichroic dyes are dissolved in a liq. crystal. CONSTITUTION:A guest-host type liq. crystal compsn. prepd. by dissolving an anthraquinone dye of formula I (wherein X is a benzene ring, S, or O; R1 and R2 are each alkyl or alkoxy) (e.g., anthraquinone blue dyes of formulae II and III) when at least two kinds of dichroic dyes are dissolved in a liq. crystal. When only one kind of the dye is used, only limited colors can be expressed. Therefore, liq. crystals having various hues have been prepared by using at least two kinds of dyes in the form of a mixture. However, the combined use of at least two kinds of dyes brought about a lowering in the light fastness of the dyes. This caused the dyes to be deteriorated upon exposure to light, so that not only the absorbency was lowered but also the color tone was changed. The use of the aforesaid dyes enables the preparation of a guest-host type liq. crystal display element exhibiting no catalytic fading and having excellent light fastness.
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