JP2011063464A - Glass plate for plasma display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the power consumption and the cost of a plasma display by conceiving the idea of a glass plate for a plasma display saving the power consumption compared with a conventional one. <P>SOLUTION: The glass plate for the plasma display contains ≤6.5 mass% alkali metal oxide (Li<SB>2</SB>O+Na<SB>2</SB>O+K<SB>2</SB>O:total of Li<SB>2</SB>O, Na<SB>2</SB>O, K<SB>2</SB>O) and has the dielectric constant of ≤6.5 in 1 MHz frequency at 25°C. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a glass plate for plasma display, and more specifically to a glass plate for plasma display capable of reducing power consumption.

  The plasma display is manufactured as follows. First, a transparent electrode made of an ITO film, a nesa film or the like is formed on the surface of the front glass plate, and a dielectric material is applied thereon and baked at a temperature of about 500 to 600 ° C. to form a dielectric layer. Further, a back dielectric material is applied to a back glass plate on which electrodes made of Al, Ag, Ni, etc. are formed, and fired at a temperature of about 500 to 600 ° C. to form a dielectric layer. A partition wall material is applied onto the substrate and baked at a temperature of about 500 to 600 ° C. to form a partition wall. Next, the front glass plate and the back glass plate are made to face each other and the electrodes and the like are aligned, and the outer periphery of the glass plate is sealed with a sealing material at a temperature of about 500 to 600 ° C. In the plasma display manufactured in this way, a vacuum discharge is caused by applying a voltage to the ITO electrode, and ultraviolet rays are generated from the Xe gas filled in the device to cause the phosphor to emit light.

Conventionally, as a glass plate for plasma display, a glass plate having a dielectric constant of 7.6 at 25 ° C. and a frequency of 1 MHz (thermal expansion coefficient: about 84 × 10 ⁻⁷ / ° C., strain point: about 580 ° C., plate thickness: 1. 8 to 3.0 mm) is used, and this glass plate is generally formed by a float process.

  Plasma displays are being promoted to further reduce power consumption.

  However, in the conventional glass plate, when a voltage is applied to an electrode such as ITO, a charge opposite to that is easily induced on the glass plate, and the voltage to be applied to the pixel electrode is lowered by the induced charge, As a result, there is a problem that the driving voltage is increased and the power consumption of the plasma display is increased. Further, when the driving voltage is increased, a general-purpose driver cannot be used, and there is a problem that it is difficult to reduce the manufacturing cost of the plasma display.

  Therefore, the present invention has a technical problem to reduce the power consumption and the cost of the plasma display by creating a glass plate for plasma display capable of lowering the power consumption than before.

As a result of repeating various experiments, the inventor regulates the content of the alkali metal oxide in the glass composition to a predetermined amount or less, and regulates the dielectric constant of the glass plate to a predetermined value or less. It is found that the technical problem can be solved, and is proposed as the present invention. That is, the glass plate for plasma display of the present invention has a content of alkali metal oxide (Li ₂ O + Na ₂ O + K ₂ O: total amount of Li ₂ O, Na ₂ O, K ₂ O) in the glass composition of 6. 5% by mass or less, and a dielectric constant at 25 ° C. and a frequency of 1 MHz is 6.5 or less. Here, “dielectric constant at 25 ° C. and frequency of 1 MHz” refers to a value measured by a method based on ASTM D150.

  The glass plate for a plasma display of the present invention regulates the dielectric constant at 25 ° C. and a frequency of 1 MHz to 6.5 or less. In this way, the power consumption of the plasma display can be reduced.

  In the glass plate for plasma display of the present invention, the content of alkali metal oxide in the glass composition is regulated to 6.5% by mass or less. In this way, the dielectric constant, dielectric loss tangent and thermal expansion coefficient of the glass plate can be significantly reduced, and the strain point can be easily increased.

Second, the glass plate for plasma display of the present invention has a thermal expansion coefficient of 25 to 60 × 10 ⁻⁷ / ° C. Conventionally, the thermal expansion coefficient of the peripheral material (insulating layer, partition wall, sealing material) of the glass plate for plasma display is 70 to so as to match the thermal expansion coefficient of the glass plate (about 84 × 10 ⁻⁷ / ° C.). It was adjusted to 90 × 10 ⁻⁷ / ° C. However, when sealing a glass plate using laser light, if the glass plate has a high coefficient of thermal expansion, the glass plate may be damaged during laser light irradiation. Therefore, if the thermal expansion coefficient of the glass plate is in the above range, such a situation can be easily prevented. Here, the “thermal expansion coefficient” refers to an average value measured with a dilatometer in a temperature range of 30 to 380 ° C.

  Third, the glass plate for plasma display of the present invention has a strain point of 590 ° C. or higher. Since a conventional glass plate for plasma display has a strain point of about 580 ° C., heat treatment or heat shrinkage occurs when heat treatment is performed at a temperature of 570 to 600 ° C. As a result, the front glass plate and the rear glass plate are opposed to each other. However, it has been difficult to align the electrodes with high accuracy, which has been an obstacle to increasing the size and definition of the plasma display. Therefore, such a situation can be prevented by setting the strain point of the glass plate within the above range. Here, the “strain point” refers to a value measured based on the method of ASTM C336.

  Fourth, the glass plate for plasma display of the present invention is characterized in that a dielectric loss tangent at 25 ° C. and a frequency of 1 MHz is 0.5 or less. Here, “dielectric loss tangent at 25 ° C. and frequency 1 MHz” refers to a value measured by a method based on ASTM D150.

Fifth, a glass plate for a plasma display of the present invention has a glass composition, in _{mass%, SiO 2 40~80%, Al} 2 O 3 0~20%, B 2 O 3 0~30%, MgO 0~ 15%, CaO 0~15%, SrO 0~15%, BaO 0~15%, characterized by containing _{Li 2 O + Na 2 O +} K 2 O 0~6.5%.

Sixth, a glass plate for a plasma display of the present invention has a glass composition, in _{mass%, SiO 2 55~80%, Al} 2 O 3 10~20%, B 2 O 3 3~19%, MgO 0~ 10%, CaO 1~10%, SrO 0~8%, BaO 0~13%, and wherein the _{Li 2 O + Na 2 O +} K 2 contain O Less than six%.

Seventh, the glass plate for a plasma display of the present invention has, as a glass composition, mass%, SiO ₂ 55 to 70%, Al ₂ O ₃ 10 to 20%, B ₂ O ₃ 7 to 19%, MgO 0 to 10%, CaO 3~10%, SrO 0~8%, BaO 0~1%, characterized by containing _{Li 2 O + Na 2 O +} K 2 O 0~0.1%.

Eighth, the glass plate for a plasma display of the present invention has, as a glass composition, mass%, SiO ₂ 55 to 70%, Al ₂ O ₃ 10 to 20%, B ₂ O ₃ 7 to 19%, MgO 0 to 3%, CaO 6~10%, SrO 0~5%, BaO 0~12%, characterized by containing _{Li 2 O + Na 2 O +} K 2 O 0~0.1%.

Ninth, the glass plate for plasma display of the present invention is characterized by having a liquidus viscosity of 10 ^4.0 dPa · s or more. “Liquid phase viscosity” refers to a value obtained by measuring the viscosity of glass at the liquid phase temperature by a platinum ball pulling method. In addition, the “liquid phase temperature” passes through a standard sieve 30 mesh (500 μm), and the glass powder remaining in 50 mesh (300 μm) is put in a platinum boat and kept in a temperature gradient furnace for 24 hours to precipitate crystals. Refers to the value measured for temperature.

  Tenth, the glass plate for plasma display of the present invention is formed by an overflow downdraw method. Here, the “overflow down draw method” is also referred to as a fusion method, in which molten glass overflows from both sides of a heat-resistant cage-like structure, and the overflowing molten glass joins at the lower end of the cage-like structure. However, this is a method of producing a glass plate by drawing downward.

  Eleventh, a plasma display according to the present invention includes the glass plate for plasma display described above.

In the glass plate for plasma display of the present invention, the content of Li ₂ O + Na ₂ O + K ₂ O in the glass composition is 6.5% by mass or less, preferably 6% by mass or less, more preferably 3% by mass or less, still more preferably. It is preferably 1% by mass or less, particularly preferably 0.1% by mass or less, and ideally not substantially contained. When the content of Li ₂ O + Na ₂ O + K ₂ O is more than 6.5% by mass, the dielectric constant and dielectric loss tangent are remarkably increased, the thermal expansion coefficient is increased, and the strain point is liable to be lowered. Here, "substantially free of _{Li 2 O + Na 2 O +} K 2 O ", the content of _{Li 2 O + Na 2 O +} K 2 O in the glass composition refers to a case of less than 0.1%.

  In the glass plate for plasma display of the present invention, the dielectric constant at 25 ° C. and a frequency of 1 MHz is 6.5 or less, 6 or less, 5.8 or less, 5.5 or less, 5.4 or less, 5.2 or less, 5 or less, 5 Below, 4.9 or less, especially 4.8 or less are preferred. When the dielectric constant increases, the induced charge increases when a voltage is applied to the pixel electrode, and the power consumption of the plasma display increases.

  In the glass plate for a plasma display of the present invention, the dielectric loss tangent at 25 ° C. and a frequency of 1 MHz is 0.5 or less, 0.1 or less, 0.01 or less, 0.005 or less, 0.001 or less, particularly 0.0005 or less. preferable. When the dielectric loss tangent increases, the glass plate generates heat when a voltage is applied to the pixel electrode, which may adversely affect the operating characteristics of the plasma display.

In the glass plate for a plasma display of the present invention, the density is 2.6 g / cm ³ or less, 2.5 g / cm ³ or less, 2.45 g / cm ³ or less, 2.42 g / cm ³ or less, 2.40 g / cm ³ Hereinafter, it is preferably 2.38 g / cm ³ or less, 2.35 g / cm ³ or less, and particularly preferably 2.34 g / cm ³ or less. When the density is larger than 2.6 g / cm ³ , it is difficult to reduce the weight of the glass plate. Here, “density” refers to a value measured by the well-known Archimedes method.

In the glass plate for a plasma display of the present invention, the thermal expansion coefficient of ^{30~60 × 10 -7 / ℃, 32~60} × 10 -7 / ℃, 32~55 × 10 -7 / ℃, especially 32-50 × 10 ^-7 / ° C is preferred. When the thermal expansion coefficient is out of the above range, the glass plate tends to warp due to the difference in thermal expansion coefficient from the dielectric layer and the electrode, and the glass plate tends to break after irradiation with laser light.

  In the glass plate for plasma display of the present invention, the strain point is preferably 590 ° C. or higher, 620 ° C. or higher, 630 ° C. or higher, 640 ° C. or higher, 650 ° C. or higher, particularly 660 ° C. or higher. When the strain point is low, in the plasma display manufacturing process, the glass plate is easily heat-shrinked during the heat treatment, so that it is difficult to manufacture a high-definition display.

In the glass plate for plasma display of the present invention, the temperature at 10 ^2.5 dPa · s is preferably 1620 ° C. or lower, 1590 ° C. or lower, 1580 ° C. or lower, 1570 ° C. or lower, 1560 ° C. or lower, particularly 1550 ° C. or lower. High temperature melting increases the burden on the glass melting furnace. Refractories such as alumina and zirconia used in a glass melting furnace are eroded violently by molten glass as the temperature rises. When the erosion amount of the refractory is increased, the life cycle of the glass melting furnace is shortened, and as a result, the manufacturing cost of the glass plate is increased. Moreover, when performing high temperature melting, since it is necessary to use a highly heat-resistant structural member for the structural member of a glass melting kiln, the structural member of a glass melting kiln becomes expensive, As a result, a melting cost rises. Furthermore, high-temperature melting requires the interior of the glass melting furnace to be kept at a high temperature, which increases the running cost of the glass melting furnace. When the temperature at 10 ^2.5 dPa · s is higher than 1620 ° C., low-temperature melting becomes difficult and the bubble quality is liable to be lowered, and as a result, the production cost of the glass plate is likely to increase. Here, “temperature at 10 ^2.5 dPa · s” corresponds to the melting temperature and indicates a value measured by a platinum ball pulling method.

  In the glass plate for plasma display of the present invention, the liquidus temperature is preferably 1180 ° C. or lower, 1150 ° C. or lower, 1110 ° C. or lower, particularly 1070 ° C. or lower. In this way, devitrification crystals are less likely to occur, and it becomes easier to form a glass plate by the overflow down draw method or the like. For this reason, the manufacturing cost of a glass plate can be reduced, improving the surface quality of a glass plate. The liquidus temperature is an index of devitrification resistance. The lower the liquidus temperature, the better the devitrification resistance.

In the glass plate for plasma display of the present invention, the liquid phase viscosity is 10 ^4.5 dPa · s or more, 10 ^5.0 dPa · s or more, 10 ^5.5 dPa · s or more, 10 ^5.7 dPa · s or more, In particular, 10 ^5.8 dPa · s or more is preferable. In this way, devitrification crystals are less likely to occur during molding, making it easier to mold the glass plate by the overflow downdraw method, etc., and improving the surface quality of the glass plate while reducing the manufacturing cost of the glass plate. can do. The liquid phase viscosity is an index of moldability. The higher the liquid phase viscosity, the better the moldability.

  In the glass plate for plasma display of the present invention, the average surface roughness Ra is preferably 50 mm or less, 30 mm or less, 10 mm or less, 5 mm or less, 3 mm or less, particularly 2 mm or less. When the average surface roughness Ra is increased, the quality of the conductive film and dielectric layer formed on the surface of the glass plate is lowered, which may cause a display failure of the plasma display. Here, “average surface roughness (Ra)” refers to a value measured by a method based on JIS B0601: 2001.

  The reason for limiting the content of each component in the glass composition as described above in the glass plate for plasma display of the present invention will be described below.

The content of SiO ₂ is 40 to 80%, preferably 50 to 70%, more preferably 55 to 70%, still more preferably 57 to 63%, and most preferably 58 to 62%. When the content of SiO ₂ is less than 45%, it is difficult to lower the density. On the other hand, when the content of SiO ₂ is more than 75%, the high-temperature viscosity is increased and the meltability is lowered, and in addition, defects such as devitrified crystals (cristobalite) are likely to occur in the glass.

The content of Al ₂ O ₃ is 0 to 20%. When the content of Al ₂ O ₃ is less or hardly enhance the heat resistance, the higher the viscosity at high temperature, the melting property tends to decrease. Therefore, the preferred lower limit range of Al ₂ O ₃ is 0.1% or more, 3% or more, 5% or more, 10% or more, 12% or more, 14% or more, 14.5% or more, 15% or more, particularly 15 .5% or more. On the other hand, when the content of Al ₂ O ₃ is large, the liquidus temperature increases, devitrification resistance tends to decrease. Therefore, the preferable upper limit range of Al ₂ O ₃ is 19% or less, 18% or less, and particularly 17% or less.

B ₂ O ₃ is a component that lowers the dielectric constant, and is a component that acts as a flux, lowers the high-temperature viscosity, and increases the meltability, and its content is 0 to 30%. When the content of B ₂ O ₃ is small, it becomes difficult to lower the dielectric constant, and the function as a flux becomes insufficient, so that the high-temperature viscosity becomes high and the foam quality is liable to be lowered. Becomes difficult to decrease in density. Therefore, a preferable lower limit range of B ₂ O ₃ is 0.1% or more, 1% or more, 3% or more, 7% or more, 8% or more, 11% or more, 13% or more, 15% or more, particularly 15.5. % Or more. On the other hand, if the content of B ₂ O ₃ is large, heat resistance and weather resistance tends to lower. Therefore, the preferable upper limit range of B ₂ O ₃ is 25% or less, 20% or less, 19% or less, 18% or less, particularly 17% or less.

  MgO is a component that increases the meltability by lowering the high-temperature viscosity without lowering the strain point, and is the component that has the effect of reducing the density most among the alkaline earth metal oxides. 0 to 15%, preferably 0 to 10%, 0 to 5%, 0 to 4%, 0 to 3%, particularly preferably 0 to 0.5%. However, when the content of MgO is large, the dielectric constant and dielectric loss tangent tend to be high. In addition, if the content of MgO is large, the density and thermal expansion coefficient become too high, the liquidus temperature rises, the devitrification resistance tends to decrease, and the glass tends to separate into phases, and transparency. May be damaged.

  The content of CaO is 0 to 15%. CaO is a component that lowers the high-temperature viscosity without significantly lowering the strain point and significantly increases the meltability, and is a component that has a large effect of suppressing devitrification in the glass composition system according to the present invention. Furthermore, when the content is relatively increased in the alkaline earth metal oxide, the glass is easily reduced in density. Therefore, the preferable lower limit range of CaO is 1% or more, 2% or more, 3% or more, 6% or more, 6.5% or more, particularly 7% or more. On the other hand, when the content of CaO is large, the dielectric constant and dielectric loss tangent are likely to be high, the thermal expansion coefficient and density are excessively high, the balance of components of the glass composition is impaired, and devitrification resistance is likely to be reduced. Become. Therefore, the preferable upper limit range of CaO is 9.5% or less, 9% or less, and particularly 8.5% or less.

  The content of SrO is 0 to 15%. SrO is a component that increases the meltability by lowering the high temperature viscosity without lowering the strain point. However, as the SrO content increases, the dielectric constant and dielectric loss tangent tend to increase, and the density and thermal expansion coefficient. Will also rise. In addition, when the SrO content increases, in order to maintain an appropriate thermal expansion coefficient, the content of CaO and MgO must be relatively decreased. It becomes easy to invite the situation where permeability falls and high temperature viscosity rises. Therefore, the content of SrO is preferably 0 to 10%, 0 to 7%, 0 to 5%, 0 to 3%, 0 to 1%, particularly preferably 0 to 0.1%.

  The content of BaO is 0 to 15%. BaO is a component that increases the meltability by lowering the high-temperature viscosity without lowering the strain point. However, as the content of BaO increases, the density and thermal expansion coefficient tend to increase, and the dielectric constant and dielectric loss tangent. Will also rise. Further, when the content of BaO increases, in order to maintain an appropriate thermal expansion coefficient, the content of CaO and MgO must be relatively decreased, and as a result, the devitrification resistance decreases, It becomes easy to invite the situation where high temperature viscosity rises. Therefore, the BaO content is preferably 0 to 13%, 0 to 5%, 0 to 3%, 0 to 1%, 0 to 0.5%, particularly preferably less than 0 to 0.1%.

  MgO + CaO + SrO + BaO (content of MgO, CaO, SrO, BaO) is a component that lowers the liquidus temperature and makes it difficult to generate crystalline foreign matter in the glass, and is a component that improves meltability and moldability, and its content The amount is preferably 0 to 25%, 1 to 20%, 3 to 15%, 5 to 11%, 6.5 to 11%, 7% to 10%, particularly preferably 7 to 9.5%. When the content of MgO + CaO + SrO + BaO is small, the function as a flux cannot be sufficiently exhibited, and in addition to the decrease in meltability, the thermal expansion coefficient becomes too low. On the other hand, when there is much content of MgO + CaO + SrO + BaO, while a dielectric constant and a dielectric loss tangent will become high, a density will rise and it will become difficult to reduce the weight of glass. Furthermore, the specific Young's modulus decreases and the thermal expansion coefficient becomes too high.

As described above, the content of Li ₂ O + Na ₂ O + K ₂ O is 0 to 6.5%, preferably 0 to 6%, 0 to 3%, 0 to 1%, particularly preferably 0 to 0.1%. Therefore, it is desirable that it is not substantially contained. When the content of Li ₂ O + Na ₂ O + K ₂ O increases, the dielectric constant, dielectric loss tangent, and thermal expansion coefficient increase, and the strain point tends to decrease.

  In addition to the above components, other components can be added to the glass composition, for example, up to 25% (preferably 15%).

A fining agent is a component used to improve foam quality. Conventionally, As ₂ O ₃ and Sb ₂ O ₃ have been used as fining agents. However, As ₂ O ₃ and Sb ₂ O ₃ are environmentally hazardous substances, and it is required to reduce their usage from an environmental point of view. The present invention does not completely exclude the inclusion of As ₂ O ₃ and Sb ₂ O ₃ , but from an environmental viewpoint, the content of these components is less than 0.1%, particularly less than 0.05%, respectively. It is preferable to restrict to.

As the fining agent, SnO ₂ is preferable. SnO ₂ is a component that exhibits a good clarification action in a high temperature range and a component that lowers the high temperature viscosity, and its content is 0 to 1%, 0.001 to 1%, 0.01 to 0.00. 5%, particularly 0.05 to 0.3% is preferable. If the content of SnO ₂ is more than 1%, SnO ₂ devitrified crystals are likely to precipitate. Incidentally, when the content of SnO ₂ is less than 0.001%, it becomes difficult to enjoy the effect of the above.

  Halogens such as F and Cl have the effect of lowering the melting temperature and promoting the action of the clarifying agent. As a result, the lifetime of the glass production kiln can be extended while lowering the melting cost. However, if the content of F or Cl is too large, the metal wiring pattern formed on the glass may be corroded. Therefore, the contents of F and Cl are preferably 1% or less, 0.5% or less, less than 0.1%, 0.05% or less, particularly 0.01% or less, respectively.

As described above, SnO ₂ is suitable as a fining agent, but unless the glass properties are impaired, CeO ₂ , SO ₃ , C, and metal powder (eg, Al, Si, etc.) are added up to 5% as a fining agent. can do.

  ZnO is a component that enhances meltability, but as its content increases, the dielectric constant and dielectric loss tangent increase, the glass tends to devitrify, the strain point decreases, and the density also increases easily. Become. Therefore, the content of ZnO is preferably 0 to 10%, 0 to 5%, 0 to 3%, 0 to 0.5%, particularly preferably 0 to 0.3%, and ideally not substantially contained. desirable. Here, “substantially does not contain ZnO” refers to a case where the content of ZnO in the glass composition is 0.1% or less.

ZrO ₂ is a component that enhances the weather resistance, but as its content increases, the dielectric constant and dielectric loss tangent increase. Therefore, the content of ZrO ₂ is preferably 0 to 5%, 0 to 3%, 0 to 0.5%, particularly preferably 0.01 to 0.2%, and is substantially contained from the viewpoint of improving devitrification resistance. Preferably not. Here, “substantially does not contain ZrO ₂ ” refers to a case where the content of ZrO _{2 in} the glass composition is 0.01% or less.

TiO ₂ is a component that lowers the viscosity at high temperature and increases the meltability, and is a component that suppresses solarization, but when added in a large amount in the glass composition, the dielectric constant and dielectric loss tangent increase, and the glass is colored. , The transmittance tends to decrease. Therefore, the content of TiO ₂ is preferably 0 to 5%, 0 to 3%, 0 to 1%, particularly preferably 0 to 0.02%.

P ₂ O ₅ is a component that enhances devitrification resistance. However, when it is added in a large amount in the glass composition, in addition to the occurrence of phase separation and milk white in the glass, the water resistance is significantly reduced. Therefore, the content of P ₂ O ₅ is preferably 0 to 5%, 0 to 1%, particularly preferably 0 to 0.5%.

Y ₂ O ₃ , Nb ₂ O ₅ , and La ₂ O ₃ have a function of increasing the strain point. However, when the content thereof is large, the dielectric constant, dielectric loss tangent, and density are likely to increase. Therefore, the content of these components is preferably 0 to 3%, 0 to 1%, particularly preferably 0 to 0.1%, respectively.

When the glass composition range is defined as follows, it becomes easy to produce a glass having a low dielectric constant and a low thermal expansion coefficient.
(1) as a glass composition, in _{mass%, SiO 2 50~70%, Al} 2 O 3 10~20%, B 2 O 3 0~20%, MgO + CaO + SrO + BaO 5~25%, 0~10% MgO, CaO 0 to 15% SrO 0 to 7% contained 0 to 15% BaO, and the content of _{Li 2 O + Na 2 O +} K 2 O is less than 6%,
(2) as a glass composition, in _{mass%, SiO 2 50~70%, Al} 2 O 3 12~18%, B 2 O 3 1~18%, MgO + CaO + SrO + BaO 5~25%, 0~8% MgO, CaO 3 to 12% SrO less than six% BaO containing 0-14%, and the content of _{Li 2 O + Na 2 O +} K 2 O is less than 5%,
(3) as a glass composition, in _{mass%, SiO 2 50~65%, Al} 2 O 3 13~18%, B 2 O 3 5~12%, MgO + CaO + SrO + BaO 7~25%, 0~5% MgO, CaO 5 -12%, SrO 0-4%, BaO 0-14%, Li ₂ O + Na ₂ O + K ₂ O content is less than 1%, As ₂ O ₃ content is less than 0.1%, Sb ₂ O ₃ content of less than 0.1%, F content of less than 0.1%, Cl content of less than 0.1%,
(4) as a glass composition, in _{mass%, SiO 2 50~65%, Al} 2 O 3 13~18%, B 2 O 3 7~11%, MgO + CaO + SrO + BaO 10~25%, 0~4% MgO, CaO 6 0.5 to 11%, SrO 0 to 4%, BaO 1 to 13%, Li ₂ O + Na ₂ O + K ₂ O content of less than 0.1%, As ₂ O ₃ content of 0.05% Less, Sb ₂ O ₃ content less than 0.05%, F content less than 0.1%, Cl content less than 0.1%,
(5) as a glass composition, in _{mass%, SiO 2 50~65%, Al} 2 O 3 13~18%, B 2 O 3 7~10%, MgO + CaO + SrO + BaO 14~25%, 0~3% MgO, CaO 7 -11%, SrO 0-3%, BaO 5-13%, and Li ₂ O + Na ₂ O + K ₂ O content is less than 0.1%, As ₂ O ₃ content is less than 0.05%, The Sb ₂ O ₃ content is less than 0.05%, the F content is less than 0.1%, and the Cl content is less than 0.1%.

If the glass composition range is defined as follows, it becomes easy to produce a glass having a low dielectric constant and a high liquidus viscosity.
(6) as a glass composition, in _{mass%, SiO 2 55~70%, Al} 2 O 3 10~18%, B 2 O 3 10~19%, MgO + CaO + SrO + BaO 3~15%, 0~3% MgO, CaO 6 -10%, SrO 0-5%, BaO 0-12%, and the content of Li ₂ O + Na ₂ O + K ₂ O is less than 0.1%,
(7) as a glass composition, in _{mass%, SiO 2 57~65%, Al} 2 O 3 12~17%, B 2 O 3 13~19%, MgO + CaO + SrO + BaO 6~11%, 0~1% MgO, CaO 7 -9%, SrO 0-5%, BaO 0-5%, SnO ₂ 0.01-0.6%, and the content of Li ₂ O + Na ₂ O + K ₂ O is less than 0.1%, As ₂ O ₃ content is less than 0.05%, Sb ₂ O ₃ content is less than 0.05%, F content is less than 0.1%, Cl content is less than 0.1%,
(8) as a glass composition, in _{mass%, SiO 2 57~63%, Al} 2 O 3 15~17%, B 2 O 3 15~18%, MgO + CaO + SrO + BaO 7~9%, 0~1% MgO, CaO 7 -9%, SrO 0-0.5%, BaO 0-0.5%, SnO ₂ 0.01-0.6%, and the content of Li ₂ O + Na ₂ O + K ₂ O is less than 0.1% The content of As ₂ O ₃ is less than 0.05%, the content of Sb ₂ O ₃ is less than 0.05%, the content of F is less than 0.1%, and the content of Cl is less than 0.1% .

  The glass plate for plasma display of the present invention is a glass batch prepared so as to have a predetermined glass composition, put into a continuous glass melting kiln, this glass batch is heated and melted, and then the obtained molten glass is clarified, It can produce by shape | molding in plate shape, after supplying to a shaping | molding apparatus.

  The glass plate for plasma display of the present invention is preferably formed by an overflow downdraw method. In this way, a glass plate that is unpolished and has good surface quality can be produced. The reason is that, in the case of the overflow downdraw method, the surface to be the surface of the glass plate is not in contact with the bowl-like refractory and is molded in a free surface state. The structure and material of the bowl-shaped structure are not particularly limited as long as desired dimensions and surface quality can be realized. In addition, the method of applying a force to the glass in order to perform the downward stretch molding is not particularly limited as long as desired dimensions and surface quality can be realized. For example, a method may be adopted in which a heat-resistant roll having a sufficiently large width is rotated and stretched in contact with glass, or a plurality of pairs of heat-resistant rolls are contacted only near the end face of the glass. It is also possible to adopt a method of stretching by stretching. In addition, it becomes easy to shape | mold a glass plate by the overflow down draw method, so that liquid phase temperature is low and liquid phase viscosity is high.

  The glass plate for plasma display of the present invention can be formed by various methods other than the overflow downdraw method, for example, the float method, the slot downdraw method, the redraw method and the like.

  Hereinafter, based on an Example, this invention is demonstrated in detail.

  Tables 1 and 2 show examples of the present invention (sample Nos. 1 to 17).

Sample no. 1-17 were produced. First, a glass batch prepared so as to have the glass composition shown in the table was placed in a platinum crucible and melted at 1600 ° C. for 24 hours, and then poured out onto a carbon plate to form a plate. Next, for each of the obtained samples, dielectric constant, dielectric loss tangent, density, thermal expansion coefficient, strain point, annealing point, softening point, temperature at 10 ⁴ dPa · s, temperature at 10 ³ dPa · s, 10 ² temperature at ^.5 dPa · s, the liquid phase temperature TL, to evaluate the liquidus viscosity LogitaTL.

  The dielectric constant and dielectric loss tangent are measured values at a frequency of 1 MHz and 25 ° C. in accordance with ASTM D150.

  The density is a value measured by a well-known Archimedes method.

  The thermal expansion coefficient is a value measured with a dilatometer, and is an average value in a temperature range of 30 to 380 ° C.

  The strain point, annealing point, and softening point are values measured based on the method of ASTM C336.

The temperature at 10 ^4.0 dPa · s, the temperature at 10 ^3.0 dPa · s, and the temperature at 10 ^2.5 dPa · s are values measured by the platinum ball pulling method.

  The liquid phase temperature TL passes through a standard sieve 30 mesh (500 μm), puts the glass powder remaining in 50 mesh (300 μm) into a platinum boat, holds it in a temperature gradient furnace for 24 hours, and measures the temperature at which crystals precipitate. It is the value.

  The liquid phase viscosity log ηTL is a value obtained by measuring the viscosity of the glass at the liquid phase temperature TL by a platinum ball pulling method.

As apparent from Tables 1 and 2, Sample No. 1 to 17 have a dielectric constant of 5.9 or less, a dielectric loss tangent of 0.0017 or less, a density of 2.63 g / cm ³ or less, a thermal expansion coefficient of 31 to 46 × 10 ⁻⁷ / ° C., and a strain point of 626 ° C. As described above, the temperature at 10 ^2.5 dPa · s was 1612 ° C. or lower, the liquid phase temperature TL was 1190 ° C. or lower, and the liquid phase viscosity logηTL was 10 ^4.0 dPa · s or higher. Sample No. 1-17 does not contain _{As 2 O 3, Sb 2 O} 3 in the glass composition, the foam quality was good.

  Sample No. described in the table. When 1 to 3 and 9 to 15 were melted in a test melting furnace and a glass plate was formed by the overflow downdraw method, the average surface roughness (Ra) was 20 mm or less. In forming the glass plate, the speed of the pulling roller, the speed of the cooling roller, the temperature distribution of the heating device, the temperature of the molten glass, the flow rate of the molten glass, the drawing speed, the rotation speed of the stirring stirrer, etc. are appropriately adjusted. The surface quality of the was adjusted.

Claims (11)

The content of the alkali metal oxide (Li ₂ O + Na ₂ O + K ₂ O) in the glass composition is 6.5% by mass or less, and the dielectric constant at 25 ° C. and a frequency of 1 MHz is 6.5 or less. A glass plate for plasma display. 2. The glass plate for plasma display according to claim 1, wherein the thermal expansion coefficient is 25 to 60 × 10 ⁻⁷ / ° C. 3.   The glass plate for a plasma display according to claim 1 or 2, wherein the strain point is 590 ° C or higher.   The glass plate for a plasma display according to any one of claims 1 to 3, wherein a dielectric loss tangent at 25 ° C and a frequency of 1 MHz is 0.5 or less. As a glass composition, in _{mass%, SiO 2 40~80%, Al} 2 O 3 0~20%, B 2 O 3 0~30%, 0~15% MgO, CaO 0~15%, SrO 0~15% _{, BaO 0~15%, Li 2 O} + Na 2 O + K 2 O 0~6.5% glass panel for a plasma display according to any one of claims 1 to 4, characterized in that it contains. As a glass composition, in _{mass%, SiO 2 55~80%, Al} 2 O 3 10~20%, B 2 O 3 3~19%, 0~10% MgO, CaO 1~10%, SrO 0~8% _{, BaO 0~13%, Li 2 O} + Na 2 O + glass panel for a plasma display according to claim 1, K 2 O, characterized in that it contains 6%. As a glass composition, in _{mass%, SiO 2 55~70%, Al} 2 O 3 10~20%, B 2 O 3 7~19%, 0~10% MgO, CaO 3~10%, SrO 0~8% _{, BaO 0~1%, Li 2 O} + Na 2 O + K 2 O 0~0.1% glass panel for a plasma display according to any one of claims 1 to 4, characterized in that it contains. As a glass composition, in _{mass%, SiO 2 55~70%, Al} 2 O 3 10~20%, B 2 O 3 7~19%, 0~3% MgO, CaO 6~10%, SrO 0~5% _{, BaO 0~12%, Li 2 O} + Na 2 O + K 2 O 0~0.1% glass panel for a plasma display according to any one of claims 1 to 4, characterized in that it contains. The glass plate for a plasma display according to any one of claims 1 to 8, wherein the liquid phase viscosity is 10 ^4.0 dPa · s or more.   The glass plate for a plasma display according to any one of claims 1 to 9, wherein the glass plate is formed by an overflow downdraw method.   A plasma display comprising the glass plate for plasma display according to claim 1.