GRADIENT DYEING METHOD OF PLASTIC LENS

PROBLEM TO BE SOLVED: To enhance the dyeing properties of a plastic lens and to enable dyeing having a concn. gradient by immersing a plastic lens in a dyeing aid aq. soln. up to a part where a concn. gradient is desired to be formed to gradually draw up the lens to wash the same and immersing the lens in a dyeing soln. to dye the same. SOLUTION: When gradient dyeing being dyeing applying a concn. gradient is applied to a plastic lens for glasses, the lens is immersed in a dyeing aid aq. soln. up to a part where a concn. gradient is desired to be formed and gradually drawn up to be washed and this lens is immersed in a dyeing soln. to be dyed. At this time, as the dyeing aid, a compd penetrating into the plastic lens and having affinity to a dye is used and, for example, an alkylnaphthalene type such as methylnaphthalene, a diphenyl type such as diphenyl, a chlorobenzene type such as trichlorobenzene and an alcohol type such as ethylene glycol are designated. The concn. of the dyeing aid of the dyeing aid aq. soln. is pref. 0.1-3.0wt.%.