US 6,274,523 B1 · Gray glass composition

Abstract

The present invention provides a glass composition having a neutral gray color and a luminous (visible) transmittance within a range that allows the glass to be used as privacy glazing in a vehicle. The glass of the present invention has a standard soda-lime-silica flat glass base composition and uses iron, cobalt and selenium, and optionally nickel, as the colorants. It has also been found that a nickel-free, neutral gray colored glass with a luminous transmittance (C.I.E. illuminant A) of up to 40% at a thickness of 3.9 millimeters may be attained by using as colorants: 0.59 to 0.99 wt. % of the total glass Fe2O3 (total iron), no greater than 0.30 wt. % FeO; 60 to 180 PPM CoO and 5 to 30 PPM Se. It has been found that a nickel-bearing, neutral gray colored glass with a luminous transmittance (C.I.E. illuminant A) of up to but less than 40% at a thickness of 3.9 millimeters may be attained by using as colorants: 0.35 to 1.1 wt. % of the total glass Fe2O3 (total iron), no greater than 0.30 wt. % FeO; 60 to 180 PPM CoO; 1 to 30 PPM Se; and 25 to 550 PPM NiO.

Claims21

Dependent claims

A neutral gray colored glass composition having a base glass portion comprising:

SiO2 66 to 75 percent by weight Na2O 10 to 20 percent by weight CaO 5 to 15 percent by weight MgO 0 to 5 percent by weight Al2O3 0 to 5 percent by weight K2O 0 to 5 percent by weight
and a colorant portion consisting essentially of:
Fe2O3 (total iron) 0.6 to 1.1 percent by weight FeO up to 0.30 percent by weight CoO 60 to 180 PPM Se 10 to 30 PPM NiO 25 to 550 PPM
the glass having a luminous transmittance of 20 to 44.5 percent at a thickness of 3.9 millimeters.

1 more element

Dependencies are inferred from the claim text.

Gray glass composition

Life of this patent

Gray glass composition

Life of this patent

Abstract

Claims21