Many attempts to introduce a dye stuff into a polymer structure have been done, in order to enhance color stability and prevent color shading. For example, Japanese Kokai Publication 203107/1986 discloses that a colored polymer is prepared using a complex of an ethylenically unsaturated sulfonic acid and a basic dye as a polymerizable dye. The obtained colored polymer, however, has very poor solubility in organic solvents.
Eur. Polym. J. Vol.23, No.8, pp 617-622, 1987 discloses a colored polymer which is prepared from an anthraquinone dye modified by methacryloyl groups. The colored polymer has not only good solubility in an organic solvent, but also a suitable solubity in water or alcohols. However, color change occurs between the anthraquinone dye and the obtained colored polymer by the function of a polymerization initiator. This makes it very difficult to control or design the color of the polymer.
Russian Patent 173410 discloses that a polymerizable dye, which is obtained by introducing an acryloyl group into aminoanthraquinone, is polymerized with styrene to obtain a colored polystyrene. In this reaction, the color of the aminoanthraquinone changes because of the modification of the chemical construction of a chromophore. The polymerizable dye of the Russian Patent has poor solubility with styrene and therefore imprarts poor color density to the obtained polystyrene.