Solvent used for recovering dyestuff from dyestuff-containing information-recording media

Abstract

The present invention provides a process for efficient recovery of dyestuffs from dye-based optical disks, and to provide a solvent used for recovery. Disclosed herein is a process for recovering dyestuffs from dye-based optical disks by treating the dyestuff-containing layer with a solvent containing a singlet oxygen quencher. Disclosed also herein is a solvent for dyestuff recovery which contains a singlet oxygen quencher.

What is claimed is:  
     
         1 . A process for recovering from dyestuff-containing information recording media having at least a dyestuff-containing layer the dyestuff contained in said dyestuff-containing layer, said process comprising treating said dyestuff-containing layer with a solvent containing a singlet oxygen quencher.  
     
     
         2 . A process for dye recovery from dyestuff-containing information recording media as defined in    claim 1   , wherein said dyestuff-containing information recording media are a dye-based optical disk of write-once type which is composed at least of a substrate, a dyestuff-containing layer as a recording layer, a reflecting film, and a protective film, which are arranged in the order mentioned, and said process comprises a first step of separating said substrate and said dyestuff-containing layer from said reflecting film and said protective film, a second step of extracting said dyestuff from said dyestuff-containing layer using a solvent containing said singlet oxygen quencher, a third step of concentrating said dyestuff which has been extracted in said second step, and a fourth step of separating said dyestuff which has been concentrated in said third step.  
     
     
         3 . A process for dye recovery from dyestuff-containing information recording media as defined in    claim 1   , wherein said solvent is freed of oxygen and subsequently incorporated with said singlet oxygen quencher and the resulting solvent is used for said dye recovery.  
     
     
         4 . A process for dye recovery from dyestuff-containing information recording media as defined in    claim 3   , wherein said solvent is freed of oxygen by introduction of an inert gas thereinto.  
     
     
         5 . A process for dye recovery from dyestuff-containing information recording media as defined in    claim 2   , wherein at least one of the first to fourth steps is carried out in an inert gas atmosphere in the dark and concentration in the third step is carried out under reduced pressure at a temperature lower than 40° C.  
     
     
         6 . A process for dye recovery from dyestuff-containing information recording media as defined in    claim 2   , wherein said solvent is one which dissolves said dyestuff but does not dissolve said substrate.  
     
     
         7 . A process for dye recovery from dyestuff-containing information recording media as defined in    claim 1   , wherein the content of said singlet oxygen quencher is more than 1 wt % of said solvent.  
     
     
         8 . A process for dye recovery from dyestuff-containing information recording media as defined in claim  1 , wherein the content of said singlet oxygen quencher is less than 10 wt % of said solvent.  
     
     
         9 . A process for dye recovery from dyestuff-containing information recording media as defined in    claim 1   , wherein said singlet oxygen quencher is at least one species selected from the group consisting of conjugated polyenes, transition metal complexes, amines including hindered amines, aminium salts, and iminium slats.  
     
     
         10 . A process for dye recovery from dyestuff-containing information recording media as defined in    claim 2   , wherein said fourth step to separate said dyestuff is carried out by using a polar solvent whose polarity is changed stepwise as the process proceeds.  
     
     
         11 . A process for dye recovery from dyestuff-containing information recording media as defined in    claim 10   , wherein said fourth step employs silica gel chromatography and said solvent is increased stepwise in polarity and the recovery of said dyestuff is accomplished at the highest polarity.  
     
     
         12 . A solvent used to recover from dyestuff-containing information recording media having at least a dyestuff-containing layer the dyestuff contained in said dyestuff-containing layer, said solvent containing therein a singlet oxygen quencher.  
     
     
         13 . A solvent for dye recovery as defined in    claim 12   , wherein said solvent is freed of oxygen and subsequently incorporated with said singlet oxygen quencher and the resulting solvent is used for said dye recovery.  
     
     
         14 . A solvent for dye recovery as defined in    claim 13   , wherein said solvent is freed of oxygen by introduction of an inert gas thereinto.  
     
     
         15 . A solvent for dye recovery as defined in    claim 12   , wherein the content of said singlet oxygen quencher is more than 1 wt % of said solvent.  
     
     
         16 . A solvent for dye recovery as defined in    claim 12   , wherein the content of said singlet oxygen quencher is less than 10 wt % of said solvent.  
     
     
         17 . A solvent for dye recovery as defined in    claim 12   , wherein said singlet oxygen quencher is at least one species selected from the group consisting of conjugated polyenes, transition metal complexes, amines including hindered amines, aminium salts, and iminium slats.  
     
     
         18 . A solvent for dye recovery as defined in    claim 12   , wherein said solvent is one which dissolves said dyestuff but does not dissolve said substrate.