Process for tinting a resin for optical materials

摘要

A process for tinting a resin for optical materials, the resin containing sulfur, includes dipping the resin for optical materials into a liquid containing an inorganic acid and/or an organic acid and thereafter tinting the resin. Where the organic acid is included in the liquid, the organic acid is a mixture of a first compound (I) having sulfo group and a second compound (II) having phenolic hydroxyl group but not having sulfo group, with a ratio (I)/(II) of the first compound to the second compound, in an amount by weight, being 0.01 to 2.0.