omparison of Ultraviolet Light Absorbers for Protection of Wool Against Yellowing

Abstract

The use of ultraviolet light absorbers to protect wool against yellowing by ultraviolet light is reported. The substances tested were evaluated by measuring the change in the reflectance of treated and untreated wool cloth, after irradiation with several light sources. Great differences were observed in the protection obtained from substances having similar strong absorption spectra in the ultraviolet. Substituted benzophenones were effective protective agents, but the method of application is important. The best results were ohtained with sulfonated substituted benzophenones, applied from hot. aqueous solutions having a pH of about 1.5. The protection afforded by this treatment was partly retained after washing with soap and water. Unsulfonated substituted benzophenones having about the same absorption characteristics, applied from alcoholic solutions, were inuch less effective. The implications of these results are briefly dis cussed.