JP2005213132A - Method for manufacturing glass substrate for plasma display panel and glass substrate for plasma display panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a glass substrate which does not generate a secondary waste substance such as a waste liquid and a waste abrasive, when an unnecessary plasma display panel is recycled, and the glass substrate. <P>SOLUTION: In the method for manufacturing the glass substrate for the plasma display panel, waste glass of a plasma display panel containing at least one kind selected from among a glass substrate, a dielectric, a partition and frit is used as part of glass raw materials. The glass raw materials are melted in a glass-melting furnace, and formed into the glass substrate. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for producing a glass substrate for a plasma display panel and a glass substrate for a plasma display panel.

  In the plasma display panel, a transparent electrode made of an ITO film or a nesa film is formed on the front glass substrate surface, and a dielectric material is applied thereon to form a dielectric layer. By applying a back dielectric material and a partition wall material to the surface of the back glass substrate on which electrodes made of Al, Ag, Ni, etc. are formed, a partition is formed, and then fired at a temperature of about 500 to 600 ° C., respectively. Form. Thereafter, the front glass substrate and the rear glass substrate are opposed to each other to align the electrodes and the like, and the periphery is frit-sealed at a temperature of about 500 to 600 ° C.

Conventionally, as a glass substrate used for a plasma display panel, soda lime glass (thermal expansion coefficient of about 84 × 10 ⁻⁷ / ° C.) molded to a thickness of 1.8 to 3.0 mm by a float method or the like. Has been commonly used. However, soda-lime glass has a low strain point of about 500 ° C., and thermal deformation and thermal shrinkage of the glass substrate in the heat treatment process have been a problem. Therefore, at present, in order to solve the problems of thermal deformation and thermal shrinkage, 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. Yes. (See Patent Document 1)
In addition, since the dielectric, partition, and frit are required to be able to be fired and sealed at a low temperature of 600 ° C. or lower, PbO or B ₂ O ₃ that has a large effect of reducing the melting point of glass is used. PbO—B ₂ O ₃ -based low melting glass containing a large amount is widely used. In recent years, from the viewpoint of environmental problems, a glass containing P ₂ O ₅ and SnO that does not contain PbO and can be fired and sealed at a low temperature has been proposed. (See Patent Documents 2 to 4)
JP-A-8-290938 Japanese Patent Laid-Open No. 11-21148 JP 11-292564 A JP 2002-190255 A

  Incidentally, in recent years, there has been a demand for reduction of waste and reuse of resources, and a method for recycling a plasma display panel is also being studied.

  As a specific recycling method, the plasma display panel is divided into a front glass substrate and a rear glass substrate, and dielectrics, partition walls, frit, etc. are removed by chemicals such as hydrofluoric acid and nitric acid, and polishing, and then the glass substrate is crushed and washed. Thus, it is conceivable to produce a glass piece and use it as a raw material for a glass substrate for plasma display panel.

  However, removing dielectrics, partition walls, frit, and the like from the glass substrate as described above takes time and leads to an increase in the cost of the product. In addition, secondary waste such as waste liquid, waste abrasive, and glass powder generated during polishing is generated, and these treatments also become a problem.

  An object of the present invention is to provide a glass substrate manufacturing method and a glass substrate that do not generate secondary waste such as waste liquid and waste abrasive when recycling an unnecessary plasma display panel. .

  The method for producing a glass substrate for a plasma display panel according to the present invention uses a glass substrate and waste glass of a plasma display panel containing at least one selected from a dielectric, a partition, and a frit as a part of the glass material. After melting in a glass melting furnace, it is formed into a glass substrate.

  Moreover, the glass substrate for plasma display panels of this invention is manufactured by said method, It is characterized by the above-mentioned.

  The method for producing a glass substrate for a plasma display panel according to the present invention does not require a step of removing dielectrics, barrier ribs, frit, etc. from the glass substrate in advance, so that secondary waste such as waste liquid and waste abrasives can be removed. Occurrence can be suppressed. Even if the dielectric, partition, frit and the like formed on the surface of the glass substrate are used without being removed, a glass substrate satisfying the required characteristics can be obtained by correction. Therefore, it is suitable as a method for producing a glass substrate for a plasma display panel.

  In the method for producing a glass substrate for a plasma display panel according to the present invention, waste glass containing a dielectric, a partition, a frit and the like is used as a part of a glass substrate raw material. This eliminates the need for chemicals and polishing for removing dielectrics, partition walls, frits, and the like, and can prevent the generation of secondary waste.

  Waste glass having a size of about 1 to 30 mm can be used by pulverizing them together without removing dielectrics, partition walls, frit and the like from the glass substrate. In this case, the transparent electrode such as an ITO film or a nesa film formed on the glass substrate, the electrode such as Al, Ag, or Ni, and the phosphor may not be removed.

The average composition of the waste glass obtained as described above varies depending on the types of the glass substrate, dielectric, barrier rib, and frit constituting the plasma display panel, but in terms of mass percentage, SiO ₂ 40-60%, Al ₂ O _{3 0~12%, 0~12% MgO,} CaO 0~12%, SrO 0~12%, BaO 0~12%, ZrO 2 0~8%, Na 2 O 0~8%, K 2 O 0~ 12%, PbO 0.01-7.5%, B ₂ O ₃ 0.01-7.5%, SnO ₂ 0.01-7.5%, P ₂ O ₅ 0.01-7.5% It becomes.

  As a usage-amount of said waste glass, it is preferable to mix and use with a glass raw material in the range of 1-90 mass% (preferably 1-70 mass%). If the amount of waste glass used exceeds 90%, correction becomes difficult and the characteristics required for the glass substrate cannot be satisfied. On the other hand, if the amount of waste glass used decreases, the recycling of the plasma display panel will not proceed.

When the above waste glass is used as a part of the glass substrate raw material, PbO, B ₂ O ₃ , SnO ₂ , P ₂ O _{5 and the} like, which are components not originally contained in the glass substrate, are mixed into the glass. Become. When these components are mixed in the glass, there is a concern that the characteristics of the glass may change, for example, the strain point of the glass substrate may decrease or the thermal expansion coefficient may increase. However, in this invention, the characteristic requested | required of a glass substrate can be satisfy | filled, without changing the characteristic of glass largely by adjusting the glass composition of a glass substrate according to the usage-amount of a waste glass piece.

_{Further, PbO,} as the preparation of _{B 2 O 3, SnO 2,} P 2 O 5, 0.2~7.5% in total (preferably from 0.2 to 5.5%) a glass containing It is preferable to prepare as follows. When these components increase, the strain point of the glass decreases, the coefficient of thermal expansion increases, devitrification occurs, and the characteristics required for the glass substrate cannot be satisfied. On the other hand, when these components are reduced, the plasma display panel cannot be recycled.

In addition, when a glass substrate containing a large amount of PbO, B ₂ O ₃ , SnO ₂ , and P ₂ O ₅ is melted and a glass substrate is manufactured by a float process, glass is produced in a reducing atmosphere such as molten tin, hydrogen, or nitrogen. The degree of coloring becomes stronger. However, even if the glass is colored, it can be used as a glass substrate for the back if there are no other characteristics.

When it is desired to suppress the degree of coloring of the glass and use it as a front glass substrate, it is preferable to limit the amount of waste glass used to 50% by mass or less (preferably 35% by mass or less). _{Further, PbO,} B 2 _{O 3,} the content of _{SnO 2, P 2 O 5,} 0.2~4% in total (preferably 0.2 to 2.5%) so that the glass containing It is preferable to blend. Needless to say, such a glass substrate may be used as the glass substrate for the back surface.

In the method of the present invention, glass raw materials, by mass _{percentage, SiO 2 50~75%, Al 2} O 3 0~15%, 0~15% MgO, CaO 0~15%, SrO 0~15 _{%, BaO 0~15%, ZrO 2} 0~10%, Na 2 O 0~10%, K 2 O 0~15%, PbO + B 2 O 3 + SnO 2 + P 2 O 5 0.2~6.8% of It is preferable to prepare so as to obtain a glass containing the composition.

  The reason why the ratio of each component of the glass is limited as described above in the present invention will be described below.

SiO ₂ is a component that forms a glass network former. Its content is 50-75%, preferably 52-70%, more preferably 54-68%. When the content of SiO ₂ increases, the high-temperature viscosity of the glass increases, so that melting and molding become difficult, and the thermal expansion coefficient becomes too small, making it difficult to achieve consistency with surrounding materials. On the other hand, when the content decreases, the thermal expansion coefficient increases and the thermal shock resistance of the glass tends to decrease, or the strain point of the glass tends to decrease. Cracks occur, and thermal deformation and shrinkage are likely to occur.

Al ₂ O ₃ is a component that increases the strain point of glass. Its content is 0-15%, preferably 0-13%, more preferably 0-11%. When the content of Al ₂ O ₃ increases, the high-temperature viscosity of the glass increases, and melting and molding become difficult, and the thermal expansion coefficient decreases, making it difficult to achieve consistency with surrounding materials.

  MgO is a component that remarkably lowers the high-temperature viscosity of glass and improves meltability and formability. Its content is 0-15%, preferably 0-13%, more preferably 0-10%. If the content of MgO is increased, the glass tends to be devitrified and it becomes difficult to mold.

  CaO is a component that lowers the high-temperature viscosity of the glass and improves the meltability and moldability. Its content is 0-15%, preferably 0-13%, more preferably 0-11%. If the content of CaO is increased, the glass tends to be devitrified and it becomes difficult to mold.

  SrO is a component that lowers the high-temperature viscosity of the glass and improves meltability and formability. Its content is 0-15%, preferably 0-14%, more preferably 0-12%. When the content of SrO increases, the glass tends to be devitrified and it becomes difficult to mold.

  BaO, like SrO, is a component that lowers the high-temperature viscosity of glass and improves meltability and moldability. Its content is 0 to 15%, preferably 0 to 12%, more preferably 0 to 10%. When the content of BaO is increased, the glass tends to be devitrified and it is difficult to mold.

ZrO ₂ is a component that increases the strain point of glass. Its content is 0-10%, preferably 0-9%, more preferably 0-8%. If the content of ZrO ₂ is increased, devitrification will tend to occur and molding becomes difficult.

Na ₂ O is a component that increases the meltability and moldability by controlling the thermal expansion coefficient of the glass or reducing the high-temperature viscosity of the glass. Its content is 0-10%, preferably 0-8%, more preferably 0-6%. When the content of Na ₂ O increases, the thermal expansion coefficient increases and the thermal shock resistance of the glass decreases. Moreover, it exists in the tendency for the strain point of glass to fall. Therefore, the glass substrate is easily cracked or thermally deformed or shrunk easily in the heat process when manufacturing the plasma display panel.

K ₂ O is a component that controls the coefficient of thermal expansion of glass in the same manner as Na ₂ O, or lowers the high-temperature viscosity of glass to improve meltability and moldability. The content is 0 to 15%, preferably 1 to 13%, more preferably 2 to 11%. When the content of K ₂ O increases, the thermal expansion coefficient increases and the thermal shock resistance of the glass decreases. Moreover, it exists in the tendency for the strain point of glass to fall. Therefore, the glass substrate is easily cracked or thermally deformed or shrunk easily in the heat process when manufacturing the plasma display panel.

PbO, B ₂ O ₃ , SnO ₂ , and P ₂ O ₅ are components contained in the dielectric, the partition, and the frit, and are mixed from the waste glass pieces. When the content of these components increases, the strain point of the glass decreases, the thermal expansion coefficient increases, devitrification occurs, and it becomes difficult to satisfy the characteristics required for the glass substrate. On the other hand, if the content of these components decreases, the recycling of the plasma display panel will not proceed. Therefore, the content of these components is preferably 0.2 to 7.5% in total. More preferably, it is 0.2 to 5.5%. In addition, when there is much content of these components, when manufacturing a glass substrate by the float process, although the coloring degree of glass becomes strong by reducing atmosphere, such as molten tin, hydrogen, and nitrogen, the total amount of these components is 4 If it is% or less (preferably 2.5% or less), coloring can be suppressed.

  PbO is a component that remarkably lowers the viscosity of the glass and improves the meltability and formability. However, since the strain point of the glass is also remarkably reduced, its content is preferably 6.2% or less. When the content of PbO is increased, the glass substrate is easily cracked, or is likely to be thermally deformed or contracted in the thermal process when the plasma display panel is manufactured.

Similarly to PbO, B ₂ O ₃ is a component that lowers the viscosity of the glass and improves the meltability and moldability. However, since the strain point of the glass is also significantly reduced, its content is 6.2%. The following is preferable. When the content of B ₂ O ₃ is increased, the glass substrate is easily cracked, or is likely to be thermally deformed or contracted in the heat process when manufacturing the plasma display panel. Moreover, since the volatilization amount of B ₂ O ₃ also increases, the life of the melting furnace is shortened.

SnO ₂ acts as a refining agent, but when the content increases, it becomes easy to devitrify. Therefore, the content is preferably 5% or less.

P ₂ O ₅ is a component that increases the mechanical strength of the glass. However, when the content is increased, devitrification is likely to occur. Therefore, the content is preferably 5% or less.

Further, in the present invention, in addition to the above components, in order to prevent ultraviolet coloration, the TiO ₂ up to 3%, in order to reduce the liquidus temperature, to improve the _moldability, Y _{2 O} 3, La 2 O ₃ , Nb ₂ O _{3 up} to 3% each as a colorant, Fe ₂ O ₃ , CoO, NiO, Cr ₂ O ₃ , Nd ₂ O _{3 up} to 2% each as a fining agent, As ₂ O ₃ , Sb ₂ O ₃ , SO ₃ , F, Cl and the like can be added up to 1% in total. However, when forming by the float method, As ₂ O ₃ and Sb ₂ O ₃ are reduced in the float bath to become metal foreign matter, so introduction should be avoided.

  Further, the glass substrate of the present invention is prepared by putting the glass raw material prepared so as to be in the above glass composition range into a continuous melting furnace, heating and melting the glass raw material, defoaming it, and supplying it to a molding apparatus. Can be obtained by forming into a plate shape and slowly cooling.

  As a method for forming the glass substrate, there are various forming methods such as a float method, a slot down draw method, an overflow down draw method, and a redraw method, but it is preferable to form the glass substrate into a plate shape by the float method. The reason is that in the case of the float process, it is easy to obtain a large glass substrate at a relatively low cost.

  When a glass substrate is formed by the float process, the glass may be colored by a reducing atmosphere such as molten tin, hydrogen, or nitrogen. When a colored glass substrate is used as a front glass substrate, problems such as deterioration in image quality occur. However, when the glass substrate is colored, it can be used as a back glass substrate.

  The obtained glass substrate preferably has a strain point of 570 ° C. (preferably 575 ° C.) or more. The reason is that if the strain point is low, the glass substrate is likely to undergo thermal shrinkage or thermal deformation in a heat treatment step such as film formation when manufacturing a display.

Furthermore, in order to satisfactorily perform frit sealing between the glass substrate and the peripheral material, the thermal expansion coefficient of the glass is 60 to 100 × 10 ⁻⁷ / ° C. (preferably 80 to 90 × 10 ⁻⁷ / ° C.). preferable.

  Hereinafter, the glass substrate for plasma display panels of the present invention will be described in detail based on examples.

  Table 1 shows the average composition of the waste glass pieces used in the present invention and the average composition of the glass substrate, dielectric, partition walls and frit constituting the waste glass pieces.

  Tables 2 and 3 show Examples (Sample Nos. 1 to 8) and Comparative Examples (Sample No. 9) of the present invention, respectively. Sample No. Reference numeral 9 denotes a commercially available glass substrate for a plasma display panel.

  Each sample in the table was prepared as follows.

  First, a plasma display panel composed of a glass substrate, a dielectric, a partition and a frit having the composition shown in Table 1 is pulverized to prepare waste glass pieces. Next, a waste glass piece and a glass raw material are mixed, and a preparation batch is produced so that it may become a composition of Table 2 and Table 3. Sample No. No. 9 does not use waste glass pieces for comparison, but is prepared using only glass raw materials. Next, the preparation batch was put into a platinum crucible and melted at 1550 ° C. for 4 hours. Thereafter, the molten glass is poured onto a carbon plate, formed into a plate shape, slowly cooled, then polished on both sides so that the plate thickness becomes 2.8 mm, and the obtained plate glass is cut into a size of 200 mm square. Sample glass was produced by processing.

  Each sample thus obtained was evaluated for density, thermal expansion coefficient, strain point, molding temperature, and the presence or absence of coloring of the glass surface after the reduction treatment, and the results are shown in the table.

As can be seen from the table, the sample No. About each sample of 1-8, it was 83.0-83.7 * 10 < ^-7 > / (degreeC), and had the thermal expansion coefficient which matched well with a peripheral material. Further, the strain point is 570 ° C. or higher, and thermal deformation and thermal shrinkage of the glass substrate in the heat treatment step can be suppressed. Moreover, the molding temperature was as low as 1148 ° C. or less, and the moldability was excellent. Furthermore, sample no. About 1-5, even if it exposes to the mixed gas of hydrogen and nitrogen, there is no coloring and it can be used as a glass substrate for front surfaces. No. About 6-8, although it colors when it exposes to the mixed gas of hydrogen and nitrogen, it can fully be used as a glass substrate for back surfaces.

  Regarding the thermal expansion coefficient, a cylindrical sample having a diameter of 5.0 mm and a length of 20 mm was prepared, and the average thermal expansion coefficient at 30 to 380 ° C. was measured with a dilatometer.

  Further, the strain point was measured based on ASTM C336-71. In addition, it is better that this temperature is high, and thermal deformation and thermal contraction of the glass substrate in the thermal process when manufacturing the display can be suppressed.

Regarding the molding temperature, a temperature corresponding to a glass viscosity of 10 ⁴ dPa · s was measured by a platinum ball pulling method. This molding temperature is a standard for molding molten glass into a plate-like glass substrate, and it is preferable that this temperature is low.

  About the presence or absence of coloring of the glass surface after a reduction process, it carried out as follows. First, the polished glass is placed on a platinum foil, and the platinum foil is placed in an atmosphere furnace. Subsequently, a mixed gas of hydrogen (2% by volume) and nitrogen (98% by volume) is introduced into the furnace at a rate of 2 liters per minute and held at a temperature of 1200 ° C. for 1 hour. Then, the glass was taken out and the presence or absence of coloring of glass was observed visually.

Claims (10)

  Waste glass of a plasma display panel including a glass substrate and at least one selected from a dielectric, a partition, and a frit is used as a part of the glass raw material, and the glass raw material is melted in a glass melting furnace and then molded into a glass substrate. A method for producing a glass substrate for a plasma display panel.   2. The glass substrate for a plasma display panel according to claim 1, wherein waste glass of the plasma display panel obtained by pulverizing the glass substrate without removing dielectrics, barrier ribs and frit is used as a part of the glass raw material. Production method.   The method for producing a glass substrate for a plasma display panel according to claim 1, wherein the glass raw material contains 1 to 90% by mass of waste glass. The glass raw material is prepared so as to be a glass containing 0.2 to 7.5% by mass of PbO, B ₂ O ₃ , SnO ₂ , and P ₂ O ₅ in a total amount. A method for producing a glass substrate for a plasma display panel.   The method for producing a glass substrate for a plasma display panel according to claim 1, wherein the glass raw material contains 1 to 50 mass% of waste glass. 6. The plasma display according to claim 5, wherein the glass raw material is prepared so as to be a glass containing 0.2 to 4% by mass of PbO, B ₂ O ₃ , SnO ₂ , and P ₂ O ₅ in a total amount. Manufacturing method of glass substrate for panels. By mass _{percentage, SiO 2 50~75%, Al 2} O 3 0~15%, 0~15% MgO, CaO 0~15%, SrO 0~15%, BaO 0~15%, ZrO 2 0~10% , _Na 2 O _0~10%, so that the glasses containing K 2 O 0~15%, for a plasma display panel according to claim 1, characterized in that formulating the glass raw materials A method for producing a glass substrate.   A glass substrate for a plasma display panel manufactured by the method according to claim 1.   The glass substrate for a plasma display panel according to claim 8, wherein the strain point is 570 ° C or higher. 9. The glass substrate for a plasma display panel according to claim 8, wherein the thermal expansion coefficient is 60 to 100 × 10 ⁻⁷ / ° C.