Method for tinting a sheet of polyurethane

摘要

A method of tinting a sheet of transparent polyurethane comprising a coloring operation followed by a fixation operation. The aforesaid coloring operation is carried out through immersion of the polyurethane into a bath maintained under continuous agitation and formed of a dispersion of one or several colorants in an aqueous solution containing a surfactant or wetting agent, while the aforesaid fixation operation is carried out through rinsing in a boiling aqueous solution of sodium alkyl sulfonate of the type known under the mark "Teepol". The application to a double or composite sheet preformed to a thin laminate, that is to say, one layer of a thermoplastic polyurethane and one other layer of a thermosetting polyurethane. In a particularly useful embodiment of the invention the tinted polyurethane serves as a selective filter having almost zero transmission in the so-called cutoff range of wavelengths lying between about 350-560 nm. Eyeglasses made from such lenses are useful for victims of aphakia and retinitis pigmentosa.