Soda-lime silica glass compositions and applications

Abstract

The subject of the invention is a glass composition of the silica-soda-lime type, intended for the manufacture of substrates or sheets, the said glass composition having a φ coefficient of between 0.50 and 0.85 N/(mm 2 ·° C.) and a working point of less than 1200° C.

1 . Glass composition of the silica-soda-lime type, intended for the manufacture of substrates or sheets, characterized in that the glass composition has a φ coefficient of between 0.50 and 0.85 N/(mm 2 ·° C.) and a working point of less than 1200° C.  
   
   
       2 . Glass composition according to  claim 1 , characterized in that it has a softening point of greater than 750° C.  
   
   
       3 . Glass composition according to either of claims  1  and  2 , characterized in that the working point is less than 1190° C.  
   
   
       4 . Glass composition according to one of  claims 1  to  3 , characterized in that the thermal expansion coefficient α 20-300  is between 60 and 88×10 −7 ° C. −1 .  
   
   
       5 . Glass composition of the silica-soda-lime type, intended for the manufacture of substrates or sheets according to one of the preceding claims, characterized in that it satisfies the relationship:  
       φ 2   ·c/a< 2 MPa 2 /° C. 2 .  
   
   
       6 . Glass composition according to one of the preceding claims, characterized in that it satisfies the relationship:  
       0.70 MPa 2 /° C. 2 <φ 2   ·c/a.    
   
   
       7 . Glass composition according to one of  claims 1  to  6 , characterized in that it has a strain point of greater than 570° C. and preferably greater than 600° C.  
   
   
       8 . Glass composition according to one of the preceding claims, characterized in that it contains the constituents below in the following proportions by weight:  
     
       
         
               
               
               
             
                   
                   
               
                   
                   
               
                   
                 SiO 2   
                 55-75% 
               
                   
                 Al 2 O 3   
                 0-7% 
               
                   
                 ZrO 2   
                 0-8% 
               
                   
                 Na 2 O 
                  5-10% 
               
                   
                 K 2 O 
                 0-8% 
               
                   
                 CaO 
                   8-12%. 
               
                   
                   
               
                   
                   
               
           
              
              
             
             
              
              
              
              
              
              
              
              
             
          
         
       
     
   
   
       9 . Glass composition according to  claim 8 , characterized in that it contains the constituents below in the following proportions by weight:  
     
       
         
               
               
               
             
                   
                   
               
                   
                   
               
                   
                 SiO 2   
                 69.60% 
               
                   
                 Al 2 O 3   
                 0.90% 
               
                   
                 ZrO 2   
                 2.60% 
               
                   
                 Na 2 O 
                 7.10% 
               
                   
                 K 2 O 
                 2.90% 
               
                   
                 CaO 
                 10.50% 
               
                   
                 MgO 
                 2.00% 
               
                   
                 SrO 
                 3.90% 
               
                   
                 Fe 2 O 3   
                 <0.15% 
               
                   
                 Other oxides 
                 <0.50%. 
               
                   
                   
               
                   
                   
               
           
              
              
             
             
              
              
              
              
              
              
              
              
              
              
              
              
             
          
         
       
     
   
   
       10 . Composition according to  claim 8 , characterized in that it contains the constituents below in the following proportions by weight:  
     
       
         
               
               
               
             
                   
                   
               
                   
                   
               
                   
                 SiO 2   
                 74.40%  
               
                   
                 Al 2 O 3   
                 0.95% 
               
                   
                 Na 2 O 
                 9.05% 
               
                   
                 K 2 O 
                 0.45% 
               
                   
                 CaO 
                 9.10% 
               
                   
                 MgO 
                 5.65% 
               
                   
                 Fe 2 O 3   
                 0.10% 
               
                   
                 Other oxides 
                  0.30%. 
               
                   
                   
               
                   
                   
               
           
              
              
             
             
              
              
              
              
              
              
              
              
              
              
             
          
         
       
     
   
   
       11 . Glass composition according to one of  claims 1  to  7 , characterized in that it contains the constituents below in the following proportions by weight:  
     
       
         
               
               
               
             
                   
                   
               
                   
                   
               
                   
                 SiO 2   
                 55-75% 
               
                   
                 Al 2 O 3   
                 0-7% 
               
                   
                 ZrO 2   
                 0-8% 
               
                   
                 Na 2 O 
                 2-8% 
               
                   
                 K 2 O 
                 2-8% 
               
                   
                 CaO 
                  4-11% 
               
                   
                 MgO 
                  0-4%. 
               
                   
                   
               
                   
                   
               
           
              
              
             
             
              
              
              
              
              
              
              
              
              
             
          
         
       
     
   
   
       12 . Glass composition intended for the manufacture of a thermally stable substrate or sheet according to  claims 1  to  4 , characterized in that it has a φ coefficient of less than 0.84, in that its strain point is greater than 507° C. and in that its electrical resistivity is such that log ρ (250° C.)  is greater than 6.6.  
   
   
       13 . Glass composition according to  claim 12 , characterized in that the φ coefficient is less than 0.84 and preferably greater than 0.75.  
   
   
       14 . Glass composition according to  claim 12  or  13 , characterized in that its strain point is between 530 and 590° C. and preferably between 550 and 580° C.  
   
   
       15 . Glass composition according to one of  claims 12  to  14 , characterized in that its electrical resistivity is such that log ρ (250° C.)  is greater than 8.  
   
   
       16 . Composition according to one of  claims 12  to  15 , characterized in that it contains the constituents below in the following proportions by weight:  
     
       
         
               
               
               
             
                   
                   
               
                   
                   
               
                   
                 SiO 2   
                 55-75% 
               
                   
                 Al 2 O 3   
                 0-5% 
               
                   
                 ZrO 2   
                 3-8% 
               
                   
                 Na 2 O 
                 4.5-8%   
               
                   
                 K 2 O 
                 3.5-7.5% 
               
                   
                 CaO 
                   7-11%. 
               
                   
                   
               
                   
                   
               
           
              
              
             
             
              
              
              
              
              
              
              
              
             
          
         
       
     
   
   
       17 . Use of the glass compositions as defined by any one of the preceding claims for the manufacture of monolithic glazing panels resistant to fire according to the G fire resistance classes.  
   
   
       18 . Use of the glass compositions as defined by any one of  claims 1  to  16  for the manufacture of substrates for emissive screens of the plasma-screen, electroluminescent-screen or cold-cathode-screen type, in particular using a sheet of glass cut from a ribbon of glass obtained by floating the glass on a bath of molten metal.