COMPOSITION OF COLOR GLASS AND VISION PANELS FOR CARS WITH REDUCED TRANSMITTED COLOR CHANGE.

摘要

A neutral gray glass composition for vision panels for automobiles having reduced transmitted color change characteristics, the glass composition having a base part comprising: SiO2 65 to 75 percent by weight Na2O 10 to 20 percent in weight CaO 5 to 15 percent by weight MgO 0 to 5 percent by weight To 2O 3 0 to 5 percent by weight K2O 0 to 5 percent by weight and major dyes comprising: Fe2O3 (total iron) 0.30 to 0.50 percent by weight CoO 0 to 15 ppm Se 3 to 6 ppm iron polysulfides up to 10 ppm in which the glass has a light transmittance of at least 65 percent at a thickness of 3.9 mm, a ratio redox of 0.35 to 0.60, a TEST of less than or equal to 65 percent, and a standard transmitted color change of less than 6, in which the standard transmitted color change is evaluated with respect to a material selected by the steps of: (a) determining the transmitted color value for a mat Selected material examined through a reference substrate; (b) determine the transmitted color value of the same material selected through a glass of a neutral gray glass composition; (c) determine the difference in color measured between the color values transmitted with the reference substrate and the color values transmitted from the neutral gray glass; or alternatively the standard transmitted color change is evaluated with respect to a material selected by the steps of: (a) measuring the reflectance of the selected material during a plurality of wavelengths using a reference illuminant and a measuring device; (b) measure the transmittance of a reference substrate over a plurality of wavelengths using the reference illuminant and the measuring device; (c) calculate a transmitted color change value for the selected material examined through the reference substrate; (d) measure the transmittance of a test substrate over a plurality of wavelengths using the reference illuminant and the measuring device; (e) calculate a transmitted color change value for the selected material examined through the test substrate by the formula: Tlambdaa = SIlambda xTGlambda x ROlambda x TGlambda x SOlambda in which Tlambda is the amount of light of the transmitted reference illuminant through the substrate, reflected by the material selected and retransmitted again through the substrate to the lambda wavelength measuring device, SIlambda is the relative power of the reference illuminant at a lambda wavelength, TGlambda is the transmittance of the substrate at a lambda wavelength, ROlambda is the reflectance of the selected material at a lambda wavelength and SOlambda is a triestimulus value of the standard observer at a lambda wavelength; and (f) compare the transmitted color change value of step (c) with the transmitted color change value of step (e) to determine a standard transmitted color change.