Patent Publication Number: US-2009239008-A1

Title: Low-sodium-oxide glass and glass tube

Description:
TECHNICAL FIELD 
     This invention falls within a branch of chemistry relating to the manufacture of glass and glass tubes with low sodium oxide. 
     BACKGROUND OF THE INVENTION 
     Technology and innovation on the manufacture of electrical appliances, equipment used for connection to computers, such as, flat-screen TVs, LCD, scanners, guiding equipment, all involve designs and developments into modern looks, taking into consideration convenience of users, who will be able to carry them to everywhere, and ease of move. Therefore, developments must be made with respect to appropriate size and weight. Glass tubes for the manufacture of backlights require the use of small-diameter glass. At present, there are manufacturers of glass tubes for the manufacture of backlights to accommodate the market of these electrical appliances, and they tend to expand themselves quickly. 
     Low-sodium-oxide glass tubes for the manufacture of light bulbs replace glass tubes for the manufacture of backlights, which are generally made of borosilicate glass with approx. 10-20 percent boric oxide. This makes it difficult for glass to melt and the cost of production is high. In addition, there is an important factor regarding the fairly low coefficient of expansion, α, of borosilicate glass when heated. As a result, when it is used by the light bulb manufacturing industry, it must select a metal wire for sealing with the coefficient of expansion, α, close to the fairly low coefficient of expansion, α, of borosilicate glass. Those currently used are tungsten, molybdenum and kovar wires, which are at somewhat high prices. Therefore, in the invention of low-sodium-oxide glass tubes for the manufacture of light bulbs, the coefficient of expansion, α, of the glass when heated has been adjusted and developed to a value close to that of a dumet wire, which is of lower cost. As a result, light bulb manufacturing business operators also incur lower cost. And through the preparation of chemical components of low-sodium-oxide glass tubes for the manufacture of light bulbs having regard to the glass softening point (Ts), which is lower than that of the borosilicate glass, and the working temperature (Tw), which is higher than that of the borosilicate glass, the working range becomes wider than that of the borosilicate glass by at least 450° C., which is one of the very important properties. 
     The invention of low-sodium-oxide glass tubes for the manufacture of light bulbs adds the improvement of the glass quality for the absorbance of light waves in the range of ultraviolet rays (UV). It is known that the UV light wave is dangerous, and in the invention the wave length at 313 nanometers (nm.) will be controlled through the application of cerium oxide (CeO 2 ). 
     The significant advantage of low-sodium-oxide glass tubes for the manufacture of light bulbs is the glass tube durability with chemical resistance. There has been a development of the ratio of soda ash, which yields the value of sodium oxide (Na 2 O); and potassium carbonate, which yields the value of potassium oxide (K 2 O); barium carbonate, which yields the value of barium oxide (BaO), and other chemical components that have environmental awareness without hazardous heavy metals, such as, lead (Pb), arsenic (As), cadmium (Cd), mercury (Hg), hexavalent chromium (CrVI), polybrominated biphenyl (PBB), polybrominated diphenyl ether (PBDE), etc. 
     SUMMARY OF THE INVENTION 
     An invention concerning low-sodium-oxide glass and glass tubes to replace borosilicate glass results in lower cost of production and emphasizes on an adjustment to quality for the absorbance of light in the range of ultraviolet rays (UV). The wave length will be measured at 313 nanometers (nm.). This invention comprises an adjustment to the durability of glass and glass tubes so that they have chemical resistance and physical properties through the selection of chemical components which are not hazardous to the environment. This is also a technique suitable to glass and glass tubes for the light bulb manufacturing industry and for other industries. 
    
    
     DETAILED DESCRIPTION 
     This invention results from the outcome of a study aiming at the finding of glass tubes with low-sodium-oxide for the manufacture of backlights to replace borosilicate glass so that the cost of production becomes lower and that adjustments and improvements are made to the quality for the absorbance of ultraviolet rays (UV). It is known that this UV light wave is harmful to components assembled in flat screen televisions, LCD-TFT television screens, flat screen PCs and laptops, scanners and navigation systems. According to the result of these studies in conjunction with the background as a manufacturer of both soda-lime glass and lead-free glass tubes for light bulbs, the inventor has discovered that it could adjust and improve the property regarding the transmittance of ultraviolet rays (UV) for the absorbance of the light wave controlled in the range of a 313 nanometer (nm.) wavelength by admixing a 0.1-0.6% quantity of cerium oxide (CeO 2 ), causing the light transmittance value to be less than 2.0%. In addition, the value of glass durability must be taken into consideration with a development of soda ash, which yields the value of sodium oxide (Na 2 O) less than 0.15%, thereby resulting in good chemical resistance; and potassium carbonate, which yields the value of potassium oxide (K 2 O)=12-14%; lithium carbonate (Li 2 CO 3 ), which yields the value of lithium oxide (Li 2 O)=2-4%; barium carbonate, which yields the value of barium oxide (BaO)=9-12%; strontium carbonate, which yields the value of strontium oxide (SrO)=2-5%; magnesium carbonate, which yields the value of magnesium oxide (MgO); and calcium carbonate, which yields the value of calcium oxide (CaO)=3-7%. 
     The invention of low-sodium-oxide glass tubes for the manufacture of light bulbs has improved and developed the coefficient of expansion, α, of glass when heated so that it is close to that of dumet wires, which are of lower cost. The alpha value (α) yielded will be around (92.0-99.0)×10 −7 /° C. And through the preparation of chemical components of low sodium oxide for the manufacture of backlights, having regard to the value of glass flexibility or softening (softening point), which is lower than that of borosilicate glass, i.e. the borosilicate glass softening point is &gt;700° C. and the softening point of this low-sodium-oxide glass invented is=670-700° C. and its working point, Tw, is higher than that of the borosilicate glass, its working range becomes wider than that of the borosilicate glass by at least 450° C., which range is beneficial to the light bulb manufacturing industry. 
     This invention contains a general description. It will be better understood by reference to special examples included herein only for the purpose of indication, and they are not considered limitations of the invention unless otherwise explained. 
     The invention of low-sodium-oxide glass and glass tubes comprise chemical components as follows: 55.0-70.0% SiO 2 , 2.0-4.0% Al 2 O 3 , 3.0-7.0% MgO and CaO, 2.0-5.0% SrO, 9.0-12.0% BaO, 2.0-4.0% Li 2 O, 0-0.15% Na 2 O, 12.0-14.0% K 2 O, 0.1-0.6% CeO 2 , (0.03%) Fe 2 O 3 , and (0.15%) SO 3 . 
     EXAMPLE 1 
     Prepare chemical components to calculate the quantity of raw materials to be mixed together. The raw materials are represented by percentage weight as follows: 
     
       
         
           
               
               
               
             
               
                   
                   
               
               
                   
                 Components 
                 Percent 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                 SiO 2   
                 62.80 
               
               
                   
                 Al 2 O 3   
                 4.00 
               
               
                   
                 MgO/CaO 
                 3.40 
               
               
                   
                 SrO 
                 5.00 
               
               
                   
                 BaO 
                 9.00 
               
               
                   
                 Li 2 O 
                 2.80 
               
               
                   
                 Na 2 O 
                 0.05 
               
               
                   
                 K 2 O 
                 12.70 
               
               
                   
                 CeO 2   
                 0.10 
               
               
                   
                 Fe 2 O 3   
                 0.03 
               
               
                   
                   
               
            
           
         
       
     
     The chemical components above will be applied to the calculation of the proportion of raw materials required to be mixed and melted into glass at the temperature of 1450° C. in a lab furnace. When a specimen has been obtained, steps are then taken to examine its physical properties. The result obtained is as follows: 
     
       
         
           
               
               
               
             
               
                   
                   
               
               
                   
                 Physical Properties 
                 Results Obtained 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                 Coefficient of expansion, Alpha 
                 93.1 
               
               
                   
                 (30-380° C. × 10 −7 /° C.) 
               
               
                   
                 Density (g/cc) 
                 2.656 
               
               
                   
                 Glass transition, Tg (° C.) 
                 516 
               
               
                   
                 Annealing point, Ta (° C.) 
                 569 
               
               
                   
                 Softening point, Ts (° C.) 
                 692 
               
               
                   
                 Working point, Tw (° C.) 
                 1191 
               
               
                   
                   
               
            
           
         
       
     
     From the result obtained, the working range will be 499° C. 
     Examine the chemical durability by the method under JIS R3502 (Na 2 O mg), with the use of an autoclave at 121° C. for a period of 60 minutes. The concentration (R 2 O mg/l) is as follows: 
     
       
         
           
               
               
               
             
               
                   
                   
               
             
            
               
                   
                 Na 2 O 
                 &lt;0.5 
               
               
                   
                 K 2 O 
                 10.1 
               
               
                   
                 Li 2 O 
                 2.7 
               
               
                   
                   
               
            
           
         
       
     
     EXAMPLE 2 
     Prepare chemical components to calculate the quantity of raw materials to be mixed together. The raw materials are represented by percentage weight as follows: 
     
       
         
           
               
               
               
             
               
                   
                   
               
               
                   
                 Components 
                 Percent 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                 SiO 2   
                 60.15 
               
               
                   
                 Al 2 O 3   
                 3.00 
               
               
                   
                 MgO/CaO 
                 5.00 
               
               
                   
                 SrO 
                 5.00 
               
               
                   
                 BaO 
                 11.00 
               
               
                   
                 Li 2 O 
                 2.20 
               
               
                   
                 Na 2 O 
                 0.15 
               
               
                   
                 K 2 O 
                 13.00 
               
               
                   
                 CeO 2   
                 0.50 
               
               
                   
                   
               
            
           
         
       
     
     The chemical components above will be applied to the calculation of the proportion of raw materials required to be mixed and melted into glass at the temperature of 1450° C. in a lab furnace. When a specimen has been obtained, steps are then taken to examine its physical properties. The result obtained is as follows: 
     
       
         
           
               
               
               
             
               
                   
                   
               
               
                   
                 Physical Properties 
                 Results Obtained 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                 Coefficient of expansion, Alpha 
                 93.3 
               
               
                   
                 (30-380° C. × 10 −7 /° C.) 
               
               
                   
                 Density (g/cc) 
                 2.726 
               
               
                   
                 Glass transition, Tg (° C.) 
                 531 
               
               
                   
                 Annealing point, Ta (° C.) 
                 585 
               
               
                   
                 Softening point, Ts (° C.) 
                 703 
               
               
                   
                 Working point, Tw (° C.) 
                 1183 
               
               
                   
                   
               
            
           
         
       
     
     From the result obtained, the working range will be 480° C. 
     EXAMPLE 3 
     Prepare chemical components to calculate the quantity of raw materials to be mixed together. The raw materials are represented by percentage weight as follows: 
     
       
         
           
               
               
               
             
               
                   
                   
               
               
                   
                 Components 
                 Percent 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                 SiO 2   
                 61.85 
               
               
                   
                 Al 2 O 3   
                 3.00 
               
               
                   
                 MgO/CaO 
                 5.00 
               
               
                   
                 SrO 
                 3.00 
               
               
                   
                 BaO 
                 11.00 
               
               
                   
                 Li 2 O 
                 2.50 
               
               
                   
                 Na 2 O 
                 0.15 
               
               
                   
                 K 2 O 
                 13.00 
               
               
                   
                 CeO 2   
                 0.50 
               
               
                   
                   
               
            
           
         
       
     
     The chemical components above will be applied to the calculation of the proportion of raw materials required to be mixed and melted into glass at the temperature of 1450° C. in a lab furnace. When a specimen has been obtained, steps are then taken to examine its physical properties. The result obtained is as follows: 
     
       
         
           
               
               
               
             
               
                   
                   
               
               
                   
                 Physical Properties 
                 Results Obtained 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                 Coefficient of expansion, Alpha 
                 92.3 
               
               
                   
                 (30-380° C. × 10 −7 /° C.) 
               
               
                   
                 Density (g/cc) 
                 2.68 
               
               
                   
                 Glass transition, Tg (° C.) 
                 523 
               
               
                   
                 Annealing point, Ta (° C.) 
                 578 
               
               
                   
                 Softening point, Ts (° C.) 
                 699 
               
               
                   
                 Working point, Tw (° C.) 
                 1176 
               
               
                   
                   
               
            
           
         
       
     
     From the result obtained, the working range will be 477° C. 
     EXAMPLE 4 
     Prepare chemical components to calculate the quantity of raw materials to be mixed together. The raw materials are represented by percentage weight as follows: 
     
       
         
           
               
               
               
             
               
                   
                   
               
               
                   
                 Components 
                 Percent 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                 SiO 2   
                 61.35 
               
               
                   
                 Al 2 O 3   
                 3.00 
               
               
                   
                 MgO/CaO 
                 5.00 
               
               
                   
                 SrO 
                 3.00 
               
               
                   
                 BaO 
                 11.00 
               
               
                   
                 Li 2 O 
                 3.00 
               
               
                   
                 Na 2 O 
                 0.15 
               
               
                   
                 K 2 O 
                 13.00 
               
               
                   
                 CeO 2   
                 0.50 
               
               
                   
                   
               
            
           
         
       
     
     The chemical components above will be applied to the calculation of the proportion of raw materials required to be mixed and melted into glass at the temperature of 1450° C. in a lab furnace. When a specimen has been obtained, steps are then taken to examine its physical properties. The result obtained is as follows: 
     
       
         
           
               
               
               
             
               
                   
                   
               
               
                   
                 Physical Properties 
                 Results Obtained 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                 Coefficient of expansion, Alpha 
                 95.6 
               
               
                   
                 (30-380° C. × 10 −7 /° C.) 
               
               
                   
                 Density (g/cc) 
                 2.703 
               
               
                   
                 Glass transition, Tg (° C.) 
                 511 
               
               
                   
                 Annealing point, Ta (° C.) 
                 559 
               
               
                   
                 Softening point, Ts (° C.) 
                 685 
               
               
                   
                 Working point, Tw (° C.) 
                 1150 
               
               
                   
                   
               
            
           
         
       
     
     From the result obtained, the working range will be 465° C. 
     Examine the chemical durability by the method under JIS R3502 (Na 2 O mg) using an autoclave at 121° C. for a period of 60 minutes. The concentration, R 2 O mg/l, is as follows: 
     
       
         
           
               
               
               
             
               
                   
                   
               
             
            
               
                   
                 Na 2 O 
                 &lt;0.5 
               
               
                   
                 K 2 O 
                 10.1 
               
               
                   
                 Li 2 O 
                 2.8 
               
               
                   
                   
               
            
           
         
       
     
     EXAMPLE 5 
     Prepare chemical components to calculate the quantity of raw materials to be mixed together. The raw materials are represented by percentage weight as follows: 
     
       
         
           
               
               
               
             
               
                   
                   
               
               
                   
                 Components 
                 Percent 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                 SiO 2   
                 61.35 
               
               
                   
                 Al 2 O 3   
                 2.00 
               
               
                   
                 MgO/CaO 
                 5.00 
               
               
                   
                 SrO 
                 4.00 
               
               
                   
                 BaO 
                 11.00 
               
               
                   
                 Li 2 O 
                 3.00 
               
               
                   
                 Na 2 O 
                 0.15 
               
               
                   
                 K 2 O 
                 13.00 
               
               
                   
                 CeO 2   
                 0.50 
               
               
                   
                   
               
            
           
         
       
     
     The chemical components above will be applied to the calculation of the proportion of raw materials required to be mixed and melted into glass at the temperature of 1450° C. in a lab furnace. When a specimen has been obtained, steps are then taken to examine its physical properties. The result obtained is as follows: 
     
       
         
           
               
               
               
             
               
                   
                   
               
               
                   
                 Physical Properties 
                 Results Obtained 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                 Coefficient of expansion, Alpha 
                 99.1 
               
               
                   
                 (30-380° C. × 10 −7 /° C.) 
               
               
                   
                 Density (g/cc) 
                 2.71 
               
               
                   
                 Glass transition, Tg (° C.) 
                 510 
               
               
                   
                 Annealing point, Ta (° C.) 
                 559 
               
               
                   
                 Softening point, Ts (° C.) 
                 680 
               
               
                   
                 Working point, Tw (° C.) 
                 1140 
               
               
                   
                   
               
            
           
         
       
     
     From the result obtained, the working range will be 460° C. 
     Examine the chemical durability by the method under JIS R3502 (Na 2 O mg) using an autoclave at 121° C. for a period of 60 minutes. The concentration, R 2 O mg/l, is as follows: 
     
       
         
           
               
               
               
             
               
                   
                   
               
             
            
               
                   
                 Na 2 O 
                 &lt;0.7 
               
               
                   
                 K 2 O 
                 12.9 
               
               
                   
                 Li 2 O 
                 3.6 
               
               
                   
                   
               
            
           
         
       
     
     From the abovementioned example, it was found that the chemical durability yielded the concentration of Na 2 O&lt;1.0 mg/l. 
     Bring the low-oxide-glass and glass tube from this invention with the thickness of 1.0 mm. max to test the percentage of transmittance of ultraviolet rays (UV) so that it the light wave absorbance is controlled in the wave length interval of 313 nanometers (nm.). It was found that the transmittance value&lt;2.0%.