JP2011121838A - Glass substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture a glass substrate that has a thermal expansion coefficient equivalent to that of soda lime glass, has a high strain point and is excellent in productivity. <P>SOLUTION: The glass substrate has a glass composition comprising, by mass, 40-60% SiO<SB>2</SB>, 0-15% Al<SB>2</SB>O<SB>3</SB>, 3.5-15% B<SB>2</SB>O<SB>3</SB>(but not 3.5%), 10-30% MgO+CaO+SrO+BaO (total content of MgO, CaO, SrO and BaO), 0.1-15% BaO, 1-25% Na<SB>2</SB>O+K<SB>2</SB>O (total content of Na<SB>2</SB>O and K<SB>2</SB>O), 0-15% Na<SB>2</SB>O, 0-15% K<SB>2</SB>O and 0.1-15% ZrO<SB>2</SB>, has a strain point of 570°C or higher but lower than 625°C and has a thermal expansion coefficient at 30-380°C of 60-90×10<SP>-7</SP>/°C. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a glass substrate, and more particularly to a glass substrate suitable for a plasma display panel (PDP) or a solar cell panel.

  The PDP is produced by making the front glass substrate and the rear glass substrate face each other, aligning the electrodes and the like, and then sealing the periphery at about 500 to 600 ° C. A transparent electrode made of an ITO film, a nesa film or the like is formed on the surface of the front glass substrate, and a dielectric layer is formed on the transparent electrode. An electrode made of Al, Ag, Ni or the like is formed on the surface of the rear glass substrate, and a dielectric layer and a partition are formed on the electrode. The dielectric layer and the partition are formed by heat treatment at about 500 to 600 ° C., respectively.

Conventionally, soda lime glass (thermal expansion coefficient: about 84 × 10 ⁻⁷ / ° C.) molded to a thickness of 1.5 to 3.0 mm by a float method or the like has been used as a glass substrate for PDP. However, since soda lime glass has a low strain point, it has a problem that it is easily deformed or contracted by heat treatment in the manufacturing process of the PDP. Therefore, at present, in order to suppress thermal deformation and thermal shrinkage due to heat treatment, high strain point glass having a thermal expansion coefficient equivalent to that of soda lime glass and having a strain point of 570 ° C. or higher is widely used. (See Patent Document 1).

JP-A-8-290938 JP 2002-193635 A

High strain point glass has a very high melting temperature and molding temperature compared to soda-lime glass, and therefore has low meltability and moldability. Specifically, since a conventional high strain point glass substrate has a molding temperature (temperature at a high temperature viscosity of 10 ⁴ dPa · s) of around 1200 ° C., it is difficult to mold the glass substrate at a low temperature (Patent Literature). 2). As a result, the conventional high strain point glass is inferior in productivity and higher in cost than soda lime glass.

  Then, this invention makes it a technical subject to produce the glass substrate which has a thermal expansion coefficient equivalent to soda-lime glass, is a high strain point, and is excellent in productivity.

As a result of intensive studies, the present inventors have found that the above technical problem can be solved by strictly regulating the content of each component in the glass composition, and in particular by introducing a predetermined amount of B ₂ O _3. It is proposed as an invention. That is, the glass substrate of this invention, as a glass composition, by _{mass%, SiO 2 40~60%, Al} 2 O 3 0~15%, B 2 O 3 3.5~15% ( However, 3.5% MgO + CaO + SrO + BaO (total amount of MgO, CaO, SrO, BaO) 10-30%, BaO 0.1-15%, Na ₂ O + K ₂ O (total amount of Na ₂ O, K ₂ O) 1 25%, Na ₂ O 0-15%, K ₂ O 0-15%, ZrO ₂ 0.1-15%, strain point is 570 ° C. or higher and lower than 625 ° C., and heat at 30 to 380 ° C. The expansion coefficient is 60 to 90 × 10 ⁻⁷ / ° C. Here, the “strain point” refers to a value measured based on ASTM C336-71. Moreover, "the thermal expansion coefficient in 30-380 degreeC" points out the average value measured with the dilatometer.

The glass substrate of the present invention strictly regulates the content of each component in the glass composition. In this way, the strain point and the thermal expansion coefficient are regulated within an appropriate range (for example, the strain point: 570 ° C. or more and less than 625 ° C., the thermal expansion coefficient at 30 to 380 ° C .: 60 to 90 × 10 ⁻⁷ / ° C.). It becomes easy to do. In particular, the glass substrate of the present invention contains more than 3.5% by mass of B ₂ O ₃ in the glass composition. In this way, the melting temperature and the molding temperature are significantly reduced, that is, the meltability and the moldability are significantly improved, so that the productivity of the glass substrate is improved, and as a result, the glass substrate is made inexpensive. Can do.

Second, the glass substrate of the present invention is characterized in that the temperature at 10 ⁴ dPa · s is less than 1150 ° C. Here, “temperature at 10 ⁴ dPa · s” refers to a value measured by a platinum ball pulling method. Note that the temperature at 10 ⁴ dPa · s is a temperature that serves as a guide when the molten glass is formed into a plate shape, that is, a temperature corresponding to the forming temperature, and the lower the temperature, the easier the glass substrate is formed.

  Thirdly, the glass substrate of the present invention is used for PDP.

Fourthly, the glass substrate of the present invention is characterized by being used for a solar cell panel, and particularly by being used for a CIS solar cell or a dye-sensitized solar cell. CIS solar cell on a glass substrate, Cu, an In, Ga, chalcopyrite-type compound semiconductor composed of Se, Cu (IN, Ga) Se 2 is formed as a light absorbing layer. The chalcopyrite type compound semiconductor is produced by a selenization method or the like, and the heat treatment temperature at that time is about 500 to 600 ° C. Conventionally, soda-lime glass has been used as a glass substrate in CIS solar cells. However, since soda lime glass has a low strain point, it has a problem that it is easily deformed or contracted by heat treatment in the manufacturing process of the chalcopyrite type compound semiconductor. On the other hand, the glass substrate of the present invention has a high strain point, has a thermal expansion coefficient equivalent to that of soda-lime glass, and has good productivity, and thus is suitable for this application. In addition, since the glass substrate of the present invention has a high strain point, it has a property that heat deformation and heat shrinkage hardly occur due to heat treatment (TiO ₂ firing step) in the manufacturing process of the dye-sensitized solar cell. .

  The reason why the content of each component in the glass composition is limited as described above in the glass substrate of the present invention will be described below. In addition, the following% display points out the mass% unless there is particular notice.

SiO ₂ is a component that forms a network of glass. Its content is 40-60%, preferably 43-58%, more preferably less than 45-55%. When the content of SiO ₂ is increased, the high-temperature viscosity is increased, the meltability and moldability are decreased, or the thermal expansion coefficient is excessively decreased, and it is difficult to match the thermal expansion coefficient of the surrounding material. On the other hand, when the content of SiO ₂ is reduced, the thermal expansion coefficient becomes too high, the thermal shock resistance is likely to be lowered, the strain point is liable to be lowered, and further, the heat treatment in the production process of PDP or the like, Cracks are likely to occur in the substrate and thermal deformation and thermal shrinkage are likely to occur.

Al ₂ O ₃ is a component that increases the strain point. Its content is 0 to 15%, preferably 3 to 14%, more preferably 5 to 13%. When the content of Al ₂ O ₃ increases, the high-temperature viscosity increases, the meltability and formability decrease, or the thermal expansion coefficient decreases excessively, making it difficult to match the thermal expansion coefficient of the surrounding materials.

B ₂ O ₃ is a component that lowers the high-temperature viscosity and remarkably improves the meltability and moldability, and is an essential component. The content thereof is 3.5 to 15% (excluding 3.5%), preferably 4.1 to 15%, more preferably 4.5 to 12%, still more preferably 5.1 to 10%. Is less than. As the content of B ₂ O ₃ increases, the strain point tends to decrease. On the other hand, when the content of B ₂ O ₃ is 3.5% or less, the melting temperature and the molding temperature tend to increase.

  MgO + CaO + SrO + BaO is a component that lowers the high-temperature viscosity and improves the meltability and moldability. Its content is 10-30%, preferably 15-25%. When the content of MgO + CaO + SrO + BaO is increased, the devitrification resistance is liable to be reduced, and thus it is difficult to mold the glass substrate. On the other hand, when the content of MgO + CaO + SrO + BaO decreases, the strain point tends to decrease, and the melting temperature and molding temperature tend to increase.

  MgO is a component that remarkably lowers the high-temperature viscosity and improves the meltability and moldability. Its content is 0-10%, preferably 0-9%, more preferably 0-8%. When the content of MgO is increased, the devitrification resistance is likely to be lowered, so that it is difficult to form the glass substrate.

  CaO is a component that increases the meltability and moldability by reducing the high-temperature viscosity. Its content is 0-10%, preferably 0-9%, more preferably 0-8%. When the content of CaO is increased, the devitrification resistance is likely to be lowered, so that it is difficult to mold the glass substrate.

  SrO is a component that increases the meltability and moldability by reducing the high-temperature viscosity. Its content is 0-15%, preferably 0-13%, more preferably 0-10%. When the content of SrO is increased, the devitrification resistance is likely to be lowered, so that it is difficult to form the glass substrate.

  BaO is a component that lowers the high-temperature viscosity and remarkably improves the meltability and moldability, and is an essential component. Its content is 0.1-15%, preferably 2-13%, more preferably 4-10%. When the content of BaO is increased, the devitrification resistance is likely to be lowered, so that it is difficult to form the glass substrate. On the other hand, when the content of BaO is less than 0.1%, the melting temperature and the molding temperature tend to increase.

Na ₂ O + K ₂ O is a component that lowers the high-temperature viscosity to improve the meltability and moldability, and is a component that can adjust the thermal expansion coefficient. Its content is 1 to 25%, preferably 5 to 20%. When the content of Na ₂ O + K ₂ O increases, the thermal expansion coefficient becomes too high, the thermal shock resistance tends to decrease, and the strain point tends to decrease. For this reason, the glass substrate is easily cracked or thermally deformed or contracted by heat treatment in the manufacturing process of PDP or the like. On the other hand, when the content of Na ₂ O + K ₂ O decreases, the melting temperature and the molding temperature tend to increase.

Na ₂ O is a component that lowers the high-temperature viscosity to improve the meltability and moldability, and is a component that can adjust the thermal expansion coefficient. Moreover, when using for a CIS type solar cell, it is an important component in improving photoelectric conversion efficiency. Its content is 0-10%, preferably 2-8%, more preferably 3-7%. When the content of Na ₂ O increases, the thermal expansion coefficient becomes too high, the thermal shock resistance tends to decrease, and the strain point tends to decrease. For this reason, the glass substrate is easily cracked or thermally deformed or contracted by heat treatment in the manufacturing process of PDP or the like.

K ₂ O is a component that lowers the high-temperature viscosity to improve the meltability and moldability, and is a component that can adjust the thermal expansion coefficient. The content is 0 to 15%, preferably 1 to 13%, more preferably 2 to 12%. When the content of K ₂ O increases, the thermal expansion coefficient becomes too high, the thermal shock resistance tends to decrease, and the strain point tends to decrease. For this reason, the glass substrate is easily cracked or thermally deformed or contracted by heat treatment in the manufacturing process of PDP or the like.

ZrO ₂ is a component that significantly increases the strain point and is an essential component. Its content is 0.1 to 15%, preferably 2 to 13%, more preferably 3 to 10%. When the content of ZrO ₂ increases, devitrification is likely to occur, and it becomes difficult to form the glass substrate. On the other hand, when the content of ZrO ₂ decreases, the strain point tends to decrease. Incidentally, as described above, if the content of B ₂ O ₃ is increased, but the strain point tends to be reduced, the ZrO ₂ if a predetermined amount added, it is possible to suppress such a situation.

In addition to the above components, SO ₃ , As ₂ O ₃ , Sb ₂ O ₃ , P ₂ O ₅ , F, and Cl may be added up to 2% in total in order to improve solubility, clarity, and moldability. it can. In order to improve chemical durability, La ₂ O ₃ , TiO ₂ , SnO ₂ , and ZnO can be added up to a total amount of 5%. Furthermore, in order to adjust the color tone of the glass substrate, Fe ₂ O ₃ , CoO, NiO, Nd ₂ O ₃ can be added up to 1% in total. However, when a glass substrate is formed by the float process, As ₂ O ₃ and Sb ₂ O ₃ are reduced in the float bath to become a metal foreign substance, so it is preferable to avoid the addition of these components.

Li ₂ O is a component that lowers the high-temperature viscosity and improves the meltability and moldability. However, Li ₂ O has an effect of remarkably lowering the strain point, and is therefore preferably not substantially contained. Here, “substantially does not contain Li ₂ O” refers to a case where the content of Li ₂ O in the glass composition is less than 1000 ppm.

  In the glass substrate of the present invention, the strain point is 570 ° C. or higher and lower than 625 ° C., preferably 570 ° C. or higher and 600 ° C. or lower. When the strain point is lower than 570 ° C., thermal deformation or thermal shrinkage is likely to occur due to heat treatment in the manufacturing process of PDP or the like. On the other hand, when the strain point is 625 ° C. or higher, the melting temperature and the molding temperature increase, and the manufacturing cost of the glass substrate increases.

In the glass substrate of the present invention, the thermal expansion coefficient at 30 to 380 ° C. is 60 to 90 × ^{10 -7} / ° C., preferably 65 to 90 × ^{10 -7} / ° C., more preferably 80-90 × ^{10 -7} / ° C. In this way, the thermal expansion coefficient of the glass substrate can be easily matched with the thermal expansion coefficient of the peripheral material such as the dielectric layer.

In the glass substrate of the present invention, the temperature at 10 ⁴ dPa · s is preferably less than 1150 ° C., particularly preferably less than 1100 ° C. In this way, since it becomes easy to form a glass substrate at a low temperature, the productivity of the glass substrate can be improved and the glass substrate can be made inexpensive.

  In the glass substrate of the present invention, a glass batch prepared with glass raw materials is put into a continuous melting furnace so as to have a desired glass composition, the glass batch is heated and melted, defoamed, and then supplied to a molding apparatus. And it can manufacture by shape | molding molten glass in plate shape and slowly cooling.

In producing the glass substrate of the present invention, it is preferable to use cullet as part of the glass raw material. If it does in this way, the solubility of a glass batch can be improved. In particular, it is preferable to use a cullet of an alkali-free aluminoborosilicate glass as a raw material for introducing B ₂ O ₃ . In this way, the reuse of the cullet of the alkali-free aluminoborosilicate glass can be promoted, and the content of the alkali component in the glass raw material other than the cullet is relatively increased, so that the solubility of the glass batch is further increased. be able to.

  As a glass substrate forming method, a forming method such as a float method, a slot down draw method, an overflow down draw method, or a redraw method can be employed. In particular, the float process is preferable because a large glass substrate can be efficiently formed at low cost.

  Hereinafter, the present invention will be described in detail based on examples.

  Table 1 shows Examples (Sample Nos. 1 to 8) and Comparative Examples (Sample No. 9) of the present invention.

  Each sample of Table 1 was produced as follows. First, a glass batch in which glass raw materials were prepared so as to have the glass composition in the table was put into a platinum crucible and melted at 1550 ° C. for 2 hours. Next, the molten glass was poured into a carbon mold, formed into a plate shape, and then subjected to a predetermined slow cooling treatment. Finally, processing according to the following measurements was performed on the obtained glass.

For each sample, the thermal expansion coefficient, strain point, and temperature at 10 ⁴ dPa · s were measured. The results are shown in Table 1.

  The thermal expansion coefficient is an average value measured with a dilatometer using a cylindrical sample having a diameter of 5.0 mm and a length of 20 mm as a measurement sample. The measurement temperature range is 30 to 380 ° C.

  The strain point is a value measured based on ASTM C336-71.

The temperature at 10 ⁴ dPa · s is a value measured by a platinum ball pulling method.

As is clear from Table 1, sample No. Nos. 1 to 8 are considered to easily form a glass substrate at a low temperature because the temperature at 10 ⁴ dPa · s is low. Sample No. Nos. 1 to 8 have a thermal expansion coefficient of 83 to 85 × 10 ⁻⁷ / ° C., and thus match the thermal expansion coefficients of the peripheral members of the PDP and the CIS crystal phase. Furthermore, sample no. 1 to 8 have good heat resistance because the strain point is 570 to 600 ° C. On the other hand, sample No. No. 9 is considered to be difficult to mold a glass substrate at a low temperature because the temperature at 10 ⁴ dPa · s is high.

Claims (4)

As a glass composition, in _{mass%, SiO 2 40~60%, Al} 2 O 3 0~15%, B 2 O 3 3.5~15% ( however, not including 3.5%), MgO + CaO + SrO + BaO 10~30 %, BaO 0.1-15%, Na ₂ O + K ₂ O 1-25%, Na ₂ O 0-15%, K ₂ O 0-15%, ZrO ₂ 0.1-15%, strain point Is a glass substrate characterized by having a thermal expansion coefficient at 30 to 380 ° C. of 60 to 90 × 10 ⁻⁷ / ° C. The glass substrate according to claim 1, wherein the temperature at 10 ⁴ dPa · s is less than 1150 ° C.   The glass substrate according to claim 1, wherein the glass substrate is used for a plasma display panel.   It uses for a solar cell panel, The glass substrate of Claim 1 or 2 characterized by the above-mentioned.