Low transmittance glass

Abstract

Low transmittance glass is composed of soda-lime-silica glass including 0.001 to 2 wt. % Li 2 O and, as colorant, 0.7 to 2.2 wt. % total iron oxide expressed as Fe 2 O 3 (T-Fe 2 O 3 ) . The glass has visible light transmittance (YA) of not greater than 65%, measured by using the CIE illuminant A, total solar radiation transmittance (TG) of not greater than 60%, and ultraviolet transmittance defined by ISO 9050 of not greater than 25%, when the glass has a thickness between 2.1 mm and 6 mm.

What is claimed is:  
     
         1 . Low transmittance glass composed of soda-lime-silica glass, 
 wherein said soda-lime-silica glass includes 0.001 to 2 wt. % Li 2 O and, as colorant, 0.7 to 2.2 wt. % total iron oxide expressed as Fe 2 O 3  (T-Fe 2 O 3 ); and    wherein said glass has visible light transmittance (YA) of not greater than 65%, measured by using the CIE illuminant A, total solar radiation transmittance (TG) of not greater than 60%, and ultraviolet transmittance (Tuv) defined by ISO 9050 of not greater than 25%, when said glass has a thickness between 2.1 mm and 6 mm.    
     
     
         2 . Low transmittance glass as claimed in  claim 1 , wherein Li 2 O is contained in an amount of less than 2 wt. %.  
     
     
         3 . Low transmittance glass as claimed in  claim 1 , wherein Li 2 O is contained in an amount of 0.05 to 0.5 wt. %.  
     
     
         4 . Low transmittance glass as claimed in  claim 1 , wherein said low transmittance glass includes FeO expressed as Fe 2 O 3  in an amount of 20 to 50% of T-Fe 2 O 3 .  
     
     
         5 . Low transmittance glass as claimed in  claim 1 , wherein said low transmittance glass has base glass composition consisting essentially of: 
 65 to 80 wt. % SiO 2 ;    0 to 5 wt. % Al 2 O 3 ;    0 to 10 wt. % MgO;    5 to 15 wt. % CaO wherein a total amount of MgO and CaO is 5 to 15 wt. %; 10 to 20 wt. % Na 2 O;    0 to 5 wt. % K 2 O wherein a total amount of Na 2 O and K 2 O is 10 to 20 wt. %; and    0 to 5 wt. % B 2 O 3 .    
     
     
         6 . Low transmittance glass as claimed in  claim 1 , wherein said low transmittance glass includes at least one selected from the group consisting of Se, CoO, Cr 2 O 3  and NiO as colorant.  
     
     
         7 . Low transmittance glass as claimed in  claim 6 , wherein said low transmittance glass includes 0.0001 to 0.1 wt. % Se.  
     
     
         8 . Low transmittance glass as claimed in  claim 6 , wherein said low transmittance glass includes 0.0001 to 0.1 wt. % CoO.  
     
     
         9 . Low transmittance glass as claimed in  claim 6 , wherein said low transmittance glass includes 0.001 to 2 wt. % Cr 2 O 3 .  
     
     
         10 . Low transmittance glass as claimed in  claim 6 , wherein said low transmittance glass includes 0.001 to 2 wt. % NiO.  
     
     
         11 . Low transmittance glass as claimed in  claim 1 , wherein said low transmittance glass includes at least one selected from the group consisting of TiO 2 , CeO 2 , MoO 3 , V 2 O 5  and La 2 O 3  as colorant in an amount of 0.0001 to 1 wt. %.  
     
     
         12 . Low transmittance glass as claimed in  claim 1 , wherein said low transmittance glass has visible light transmittance (YA) of 5 to 65%, measured by using the CIE illuminant A, total solar radiation transmittance (TG) of not greater than 50%, and ultraviolet transmittance (Tuv) defined by ISO 9050 not greater than 20%, when said glass has a thickness between 2.1 mm and 6 mm.