Chromium bearing forehearth color concentrate

Abstract

A forehearth color concentrate comprising a non-smelted agglomerated interspersion of particles for use in coloring, said concentrate comprising by weight from about 50% to about 95% of a glass component and from about 4% to about 50% of a binder, said glass component comprising by weight from about 15% to about 35% chromium oxide. The present invention further provides a method of using the color concentrate.

1 . A method for coloring a molten base glass in a forehearth furnace comprising the steps of: 
 (i) providing a color concentrate comprising a non-smelted agglomerated interspersion of particles, said concentrate comprising by weight from about 50% to about 95% of a glass component and from about 4% to about 50% of a binder, said glass component comprising by weight from about 15% to about 35% chromium oxide;    (ii) adding the color concentrate to the molten base glass contained in a forehearth so as to impart color to the molten base glass; and    (iii) cooling the molten base glass to form a colored glass composition.    
     
     
         2 . The method according to  claim 1  wherein the glass component comprises one or more glass frits comprising by weight from about 5% to about 30% Na 2 O, from about 15% to about 60% SiO 2 , from about 0% to about 25% B 2 O 3 , from about 0% to about 25% K 2 O, from about 0% to about 3% Li 2 O, from about 0% to about 2% Al 2 O 3 , from about 0% to about 15% CaO, from about 0% to about 5% TiO 2 , from about 0% to about 1% F 2  and from about 15% to about 35% chromium oxide.  
     
     
         3 . The method according to  claim 1  wherein the glass component comprises a glass frit comprising by weight from about 8% to about 22% Na 2 O, from about 30% to about 45% SiO 2 , from about 4% to about 18% B 2 O 3 , from about 1% to about 9% K 2 O, from about 0% to about 2% Li 2 O, from about 0% to about 1% Al 2 O 3 , from about 0% to about 5% CaO, from about 0% to about 3% TiO 2 , from about 0% to about 1% F 2 , up to about 5% coloring oxides, and from about 17% to about 33% chromium oxide.  
     
     
         4 . The method according to  claim 1  wherein the binder comprises a silicate of an alkali metal selected from the group consisting of potassium, lithium and sodium.  
     
     
         5 . A colored glass composition formed by the method of  claim 1 .  
     
     
         6 . A method for coloring a molten base glass in a forehearth furnace comprising the steps of: 
 (i) providing a color concentrate glass frit comprising weight from about 5% to about 30% Na 2 O, from about 15% to about 60% SiO 2 , from about 0% to about 25% B 2 O 3 , from about 0% to about 25% K 2 O, from about 0% to about 3% Li 2 O, from about 0% to about 2% Al 2 O 3 , from about 0% to about 15% CaO, from about 0% to about 5% TiO 2 , from about 0% to about 1% F 2  and from about 15% to about 35% chromium oxide;    (ii) adding the color concentrate to the molten glass contained in the forehearth furnace so as to impart color to the molten base glass; and    (iii) cooling molten base glass to form a colored glass composition.    
     
     
         7 . A colored glass composition formed by the method of  claim 6 .  
     
     
         8 . A method of forming a forehearth color concentrate for use in coloring glass comprising a non-smelted agglomerated interspersion of particles formed by the steps of: 
 (ii) providing one or a blend of more than one glass frit to provide a powdered glass component comprising by weight from about 15% to about 35% chromium oxide;    (ii) providing a binder;    (iii) thoroughly mixing said glass component and said binder to form a mixture; and    (iv) compacting the mixture to form said color concentrate.    
     
     
         9 . The method according to  claim 8  wherein the glass component comprises one or more glass frits comprising by weight from about 5% to about 30% Na 2 O, from about 15% to about 60% SiO 2 , from about 0% to about 25% B 2 O 3 , from about 0% to about 25% K 2 , from about 0% to about 3% Li 2 O, from about 0% to about 2% Al 2 O 3 , from about 0% to about 15% CaO, from about 0% to about 5% TiO 2 , from about 0% to about 1% F 2  and from about 15% to about 35% chromium oxide.  
     
     
         10 . The method according to  claim 9  wherein the one or more glass frits further comprise up to about 20% by weight of one or more coloring oxides.  
     
     
         11 . The method according to  claim 8  wherein the glass component comprises a glass frit comprising by weight from about 8% to about 22% Na 2 O, from about 30% to about 45% SiO 2 , from about 4% to about 18% B 2 O 3 , from about 1% to about 9% K 2 O, from about 0% to about 2% Li 2 O, from about 0% to about 1% Al 2 O 3 , from about 0% to about 5% CaO, from about 0% to about 3% TiO 2 , from about 0% to about 1% F 2 , up to about 5% coloring oxides, and from about 17% to about 33% chromium oxide.