Selenium-free sunglass material with brown tint

Abstract

UV- and IR-absorbing materials with brown tint for sunglasses are described. The sunglass materials are prepared from a base glass through a post-fabrication process that includes ion exchange with silver. The tint of the sunglass material can be adjusted by controlling the level of ion exchange of the base glass with silver by varying the conditions of ion exchange. A wide range of tint is possible, including multiple shades of brown tint. In a typical process, a base glass having strong absorption in the UV and IR is fabricated and the resulting glass is subjected to a post-fabrication silver ion exchange process to control tint. The post-fabrication silver ion exchange process permits control of tint while maintaining strong UV and IR absorption and adequate transmittance in the visible.

What is claimed is: 
     
         1 . A method for processing a glass comprising:
 placing a first glass in an ion-exchange bath, said first glass comprising B 2 O 3  and SiO 2 , said first glass lacking Se, said ion-exchange bath comprising a silver salt and introducing silver into said first glass to form a second glass.   
     
     
         2 . The method of  claim 1 , wherein said silver salt has a concentration in the range from 0.01 wt % to 1.0 wt % in said ion-exchange bath. 
     
     
         3 . The method of  claim 1 , wherein said silver salt is silver nitrate. 
     
     
         4 . The method of  claim 1 , wherein said first glass has a first average percent transmittance (% T), for a thickness of 1.9 mm, over the wavelength range from 780 nm-2000 nm and said second glass has a second average percent transmittance (% T), for a thickness of 1.9 mm, over the wavelength range from 780 nm-2000 nm, said second average percent transmittance (% T) being within the range from 50%-150% of said first average percent transmittance (% T). 
     
     
         5 . The method of  claim 4 , wherein said first glass has a third average percent transmittance (% T), for a thickness of 1.9 mm, over the wavelength range from 280 nm-400 nm and said second glass has a fourth average percent transmittance (% T), for a thickness of 1.9 mm, over the wavelength range from 280 nm-400 nm, said fourth average percent transmittance (% T) being less than 150% of said third average percent transmittance (% T). 
     
     
         6 . The method of  claim 1 , wherein said first glass has a first chromaticity coordinate x and a first chromaticity coordinate y and said second glass has a second chromaticity coordinate x and a second chromaticity coordinate y, said second chromaticity coordinate x exceeding said first chromaticity coordinate x by at least 0.05, said second chromaticity coordinate y exceeding said first chromaticity coordinate y by at least 0.04.