DYESTUFF RECOVERY METHOD FOR PRODUCTION OF OPTICAL INFORMATION RECORDING MEDIUM AND PRODUCTION OF OPTICAL INFORMATION RECORDING MEDIUM

摘要

PROBLEM TO BE SOLVED: To provide a method for recovering dyestuffs at a high purity and high yield from an excess coating liquid. SOLUTION: This method recovers the dyestuffs at the high purity from the excess coating liquid discharged in a recording layer forming process when a dyestuff recording layer is formed by a spin coating method using the coating liquid for forming the dyestuff recording layer which is prepared by dissolving the dyestuffs and color fading preventive agent into a solvent having the higher solubility in the dyestuffs than this color fading preventive agent for the production of the laser beam recording optical information recording medium. The method described above includes (1) a stage for depositing the color fading preventive agent by concentrating the excess coating liquid under reduced pressure, (2) a stage for filtering and removing the color fading preventive agent deposited from the concentrated excess coating liquid, (3) a stage for preparing the dyestuff solution by adding and mixing a solvent having the solubility in the dyestuffs this time lower than the solubility in the color fading preventive agent to and with the filtrate obtained in the stage described above, (4) a stage for depositing the dyestuffs by cooling the dyestuff solution and (5) a stage for filtering and recovering the deposited dyestuffs.