JP2008063153A - Substrate glass for display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a glass composition having a suitable thermal expansion coefficient, a low melting temperature and a high strain point, and particularly suitable to a glass substrate used in a display field and requiring high heat resistance such as a substrate for an electronic display such as a PDP (plasma display panel). <P>SOLUTION: The substrate glass for a display device substantially comprises, by wt.%, 55 to 60 SiO<SB>2</SB>, 4 to 12 Al<SB>2</SB>O<SB>3</SB>, 2 to 6% Na<SB>2</SB>O, 4 to 8 K<SB>2</SB>O, 8 to 12 R<SB>2</SB>O (in the total of Na<SB>2</SB>O and K<SB>2</SB>O), 0 to 4 MgO, 6 to 10 CaO, 0 to 6 SrO, 10 to 14 BaO, 20 to 26 R'O (in the total of MgO, CaO, SrO and BaO), and 0 to 4 ZrO<SB>2</SB>. The average linear expansion coefficient at 30 to 300°C is 80 to 84(×10<SP>-7</SP>/°C), and its strain point is ≥570°C. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a glass composition having excellent heat resistance, light weight and excellent durability. In particular, the present invention relates to a glass composition suitable for a glass substrate having an appropriate thermal expansion coefficient, a low melting temperature and a high strain point and requiring high heat resistance, for example, a substrate for electronic display such as PDP (plasma display panel).

  Conventionally, high strain point glass has been used in the PDP manufacturing field. Initially, alkali, alkaline earth, and silica glass similar to soda lime silica glass was used, and the glass had a thermal expansion coefficient close to that of soda lime silica glass. It is a high strain point glass that exceeds the range (see Patent Documents 1 to 3).

  Moreover, what adjusted the average thermal expansion coefficient in order to make the thermal contraction in a panel manufacturing process small is known (refer patent document 4).

Furthermore, since it is desirable that the PDP or the like has a high strain point, it is also known that the strain point is increased to about 600 ° C. (see Patent Document 5).
Japanese Patent Laid-Open No. 10-045423 Japanese Patent Application Laid-Open No. 11-240735 JP 2000-103638 A Japanese Patent No. 3669022 Japanese Patent No. 3770670

    However, those described in JP-A-10-045423, JP-A-11-240735 and JP-A-2000-103638 have a thermal expansion coefficient close to that of soda lime silica glass in the display panel manufacturing process. However, there is a problem that the thermal contraction is large and the thermal deformation is large in the panel manufacturing process.

  Moreover, although the thing of the said patent 3669022 gazette has an average thermal expansion coefficient which is an appropriate value regarding the thermal contraction in a panel manufacturing process, there exists a problem that a strain point is low.

  Further, the one described in the above-mentioned Japanese Patent No. 3770670 has a high strain point, but the average thermal expansion coefficient is almost the same as that of soda lime silica glass, and the thermal contraction is large, thereby solving the problem of thermal deformation in the panel manufacturing process. I can't say that.

The present invention is substantially expressed by weight%, SiO ₂ is 55-60, Al ₂ O ₃ is 4-12, Na ₂ O is 2-6, K ₂ O is 4-8, R ₂ O (Na ₂ The total amount of O and K ₂ O) is 8-12, MgO is 0-4, CaO is 6-10, SrO is 0-6, BaO is 10-14, R′O (MgO, CaO, SrO, BaO) It is a substrate glass for a display device in which the total amount) is 20 to 26 and ZrO ₂ is 0 to 4.

Moreover, it is said substrate glass for display apparatuses characterized by the average linear expansion coefficient in 30-300 degreeC being 80-84 (x10 < ^-7 > / degreeC).

  The display device substrate glass is characterized in that the strain point is 570 ° C. or higher.

  The above-mentioned substrate glass for a display device is characterized in that the melting temperature (temperature (° C.) when the viscosity is log η = 2.0) is 1520 ° C. or less.

  Furthermore, the substrate glass for a display device according to the above, characterized in that the working temperature (temperature when the viscosity is log η = 4.0 (° C.)) − Devitrification temperature is 0 ° C. or more.

The glass of the present invention has an average thermal expansion coefficient of 80 to 84 (× 10 ⁻⁷ / ° C.) in order to reduce thermal shrinkage in the panel manufacturing process, and also has a high strain point. It solves the problem of the same kind of glass. In addition, since the melting temperature is low and the viscosity is small, it is easy to melt, and in the float process production, there is also a feature that brick erosion is small.

  The glass of the present invention has an appropriate coefficient of thermal expansion and a high strain point, which has improved the problems for display substrates, particularly PDPs.

The present invention is substantially expressed by weight%, SiO ₂ is 55-60, Al ₂ O ₃ is 4-12, Na ₂ O is 2-6, K ₂ O is 4-8, R ₂ O (Na ₂ The total amount of O and K ₂ O) is 8-12, MgO is 0-4, CaO is 6-10, SrO is 0-6, BaO is 10-14, R′O (MgO, CaO, SrO, BaO) It is a substrate glass for a display device in which the total amount) is 20 to 26 and ZrO ₂ is 0 to 4.

SiO ₂ is a main component of glass, and if it is less than 55% by weight, the heat resistance, chemical durability and acid resistance of the glass deteriorate. On the other hand, if it exceeds 60%, the high-temperature viscosity of the glass melt becomes high, glass molding becomes difficult, and the devitrification temperature decreases. Moreover, the linear expansion coefficient of glass becomes too small, and the compatibility with other members constituting the display panel is deteriorated. Therefore, the range is 55-60%.

Al ₂ O ₃ is a component that increases the strain point and improves chemical durability and acid resistance. If the weight percentage is less than 4%, the heat resistance, chemical durability and acid resistance of the glass deteriorate. On the other hand, if it exceeds 12%, the melting temperature of the glass becomes high, and it becomes difficult to melt the glass. Therefore, the range of 4 to 12% is preferable.

Na ₂ O acts as a flux at the time of glass melting together with K ₂ O. If it exceeds 6%, the chemical durability and acid resistance are deteriorated and the average thermal expansion coefficient is too high. If it is less than 2%, the meltability is deteriorated and the average thermal expansion coefficient is too low. Therefore, the range is 2 to 6%.

K ₂ O also exhibits the same effect as Na ₂ O. If it exceeds 8%, the chemical durability and acid resistance are deteriorated and the average thermal expansion coefficient is too high. If it is less than 4%, the meltability is deteriorated and the average thermal expansion coefficient is too low. Therefore, the range is 4 to 8%.

Since the alkali component R ₂ O (Na ₂ O, K ₂ O) has the same effect, the total amount has an appropriate range, which is 8 to 12%. By setting it in this range, the high temperature viscosity, chemical durability, acid resistance, and average thermal expansion coefficient can be maintained in appropriate ranges. If the total amount of the alkali components is less than 8%, the high-temperature viscosity of the glass melt becomes high and glass melting becomes difficult. If it exceeds 12%, the chemical durability and acid resistance are deteriorated. Therefore, the range is 8 to 12%. More preferably, it is 10 to 12%.

  MgO is not an essential component, but has the effect of lowering the viscosity of the molten glass during glass melting. If it exceeds 4%, the tendency of devitrification of the glass will increase, making it difficult to mold the molten glass. MgO is 4% or less.

  CaO has the effect of lowering the viscosity of the molten glass at the time of melting the glass and the effect of increasing the thermal expansion coefficient of the glass. If it is less than 6%, the thermal expansion coefficient of the glass becomes too low. On the other hand, if it exceeds 10%, the tendency of devitrification increases, and it becomes difficult to mold molten glass. Therefore, the range is 6 to 10%.

  SrO is not an essential component, but has the effect of suppressing the occurrence of devitrification by lowering the high-temperature viscosity of the glass melt in the presence of CaO. If it exceeds 6%, the density becomes too high, so 6% or less is desirable. Particularly desirable is 0%.

  BaO has the effect of suppressing the devitrification tendency of the glass melt and the effect of adjusting the average thermal expansion coefficient. If it exceeds 14%, the density increases and the average thermal expansion coefficient becomes too large. If it is less than 10%, the strain point becomes too low. Therefore, 10 to 14% is desirable.

  Further, within the above composition range, the total amount of the divalent metal oxide R′O (R ′ is Mg, Ca, Sr, Ba) is set to a range of 20 to 26%, thereby improving the melting property of the glass. While maintaining the good range, the viscosity-temperature gradient is moderated to improve the moldability of the glass, and it has excellent heat resistance, chemical durability, acid resistance, etc., and obtains a glass with an appropriate range of thermal expansion coefficient. be able to. When the total amount of R′O is less than 20%, the high-temperature viscosity increases, making it difficult to melt and mold the glass. In addition, the strain point is lowered too much and the thermal expansion coefficient is lowered. On the other hand, if it exceeds 26%, the density increases, the tendency to devitrification increases, and the chemical durability decreases. A more preferable range is 20 to 22%.

ZrO ₂ is not an essential component, but has the effect of raising the strain point of the glass and improving the chemical durability of the glass. However, if it exceeds 4%, the tendency to devitrification increases and glass molding becomes difficult, so 4% or less is preferable.

Although the glass of the preferable aspect of this invention consists of said component substantially, in the range which does not impair the objective of this invention, you may contain other components to 1% in total amount. For example, a total amount of SO ₃ , Cl, F, As ₂ O _{3 and the} like may be contained up to 1% in order to improve melting, fining, and moldability of glass. Further, _Fe 2 _O 3 to color the glass, CoO, may be contained up to 1% in a total amount of NiO and the like. Further, in order to prevent electron beam browning in the PDP, TiO ₂ and CeO ₂ may each be contained up to 1% and up to 1% in total.

Moreover, this invention is said board | substrate glass for display apparatuses characterized by the average linear expansion coefficient in 30-300 degreeC being 80-84 (x10 < ^-7 > / degreeC).

The coefficient of thermal expansion is a characteristic indicating the heat resistance of glass, and if it exceeds 84 × 10 ⁻⁷ / ° C., it is unsuitable because thermal deformation becomes excessive in the manufacturing process of the display panel, and 80 to 84 × 10 ⁻⁷ / Outside the range of ° C., the amount of deformation differs from other members, which is not preferable.

  The display device substrate glass is characterized in that the strain point is 570 ° C. or higher. The strain point is also a characteristic showing the heat resistance of glass, and in the display panel, the strain point should be high as long as other properties are not impaired. Therefore, 570 ° C. or higher is appropriate. In the glass having such a composition, the upper limit is usually about 650 ° C.

  The above-mentioned substrate glass for a display device is characterized in that the melting temperature (temperature (° C.) when the viscosity is log η = 2.0) is 1520 ° C. or less. When the melting temperature exceeds 1520 ° C., it is difficult to melt the raw materials and form the glass. In the glass having such a composition, the lower limit is usually about 1400 ° C.

  Further, the substrate glass for a display device according to the above, characterized in that the working temperature (temperature when the viscosity is log η = 4.0 (° C.)) − Devitrification temperature is 0 ° C. or more. If this value is less than 0 ° C., it is difficult to produce a glass plate without causing devitrification. In the glass having such a composition, the upper limit is usually about 150 ° C.

  Hereinafter, a description will be given based on examples.

(Creation of glass)
A prepared raw material consisting of silica sand, aluminum oxide, sodium carbonate, sodium sulfate, potassium carbonate, magnesium oxide, calcium carbonate, strontium carbonate, barium carbonate and zirconium silicate is charged into a platinum crucible, and 1500-1600 ° C., about 6 in an electric furnace. It was melted by heating for hours. During the heating and melting, the glass melt was stirred with a platinum rod to homogenize the glass. Next, the molten glass was poured into a mold to form a glass block, which was transferred to an electric furnace maintained at 550 to 600 ° C. and gradually cooled in the furnace. The obtained glass sample was homogeneous without bubbles or striae.

Table 1 shows the glass composition (as oxide) based on the raw material formulation. For these glasses, the average coefficient of linear expansion (10 ⁻⁷ / ° C.) of 30 to 300 ° C., melting temperature / working temperature (° C.), strain point (° C.), devitrification temperature (° C.), and acid resistance are as follows: Measured by the method.

  The expansion coefficient measured the average linear expansion coefficient in 30-300 degreeC using the thermomechanical analyzer TMA8310 (Rigaku Denki Co., Ltd. product). Melting temperature and working temperature were measured by a ball pulling method using a ball pulling viscometer (manufactured by Opto Corporation), with log η = 2.0 and 4.0 as the melting temperature and working temperature, respectively. The strain point was measured by a beam bending method based on JIS R3103-2.

  The devitrification temperature is determined by leaving the sample in a furnace with a temperature gradient of 25 ° C. for 2 hours, and visually observing the presence or absence of devitrification, and taking the average of the lowest temperature at which devitrification disappears and the temperature below it. I asked for it.

Acid resistance treatment was performed by using a 3N HNO ₃ solution for a substrate-like sample at 40 ° C. for 1 min. From the change of reflectance, ΔR was evaluated as “Good” when ΔR was over 0.3%, and “A” was evaluated as “Good” when the acid resistance was inferior.

（結果）
表１の実施例１〜４は本発明におけるガラスであり、表２は比較例である。比較例１はソーダライムシリカガラスである。比較例２、３は従来の高歪点ガラスである。比較例１のソーダライムシリカガラスは、平均熱膨張係数が大きく、歪点が低い。比較例２の高歪点ガラスにおいては、平均熱膨張係数は適切な値であるものの、歪点が低く、溶融温度が高い。比較例３の高歪点ガラスにおいては、歪点や溶融温度は良好であるものの、平均熱膨張係数が大きすぎる。

(result)
Examples 1 to 4 in Table 1 are glasses in the present invention, and Table 2 is a comparative example. Comparative Example 1 is soda lime silica glass. Comparative Examples 2 and 3 are conventional high strain point glasses. The soda lime silica glass of Comparative Example 1 has a large average thermal expansion coefficient and a low strain point. In the high strain point glass of Comparative Example 2, although the average thermal expansion coefficient is an appropriate value, the strain point is low and the melting temperature is high. In the high strain point glass of Comparative Example 3, although the strain point and the melting temperature are good, the average thermal expansion coefficient is too large.

On the other hand, the glass of Examples 1 to 3 has a thermal expansion coefficient in the range of 80 to 84 × 10 ⁻⁷ / ° C., and a strain point, a melting temperature, and (working temperature−devitrification temperature) are desired. Is the value of Therefore, it is clear that the glass of the present invention has an appropriate coefficient of thermal expansion and a high strain point, which has improved the problems for display substrates, particularly PDPs.

  The present invention can be used not only for display panel applications such as PDP but also for the entire electronic material field requiring a heat treatment process.

Claims (5)

Substantially expressed by weight%, SiO ₂ is 55-60, Al ₂ O ₃ is 4-12, Na ₂ O is 2-6, K ₂ O is 4-8, R ₂ O (Na ₂ O and K ₂ (Total amount of O) is 8 to 12, MgO is 0 to 4, CaO is 6 to 10, SrO is 0 to 6, BaO is 10 to 14, and R'O (total amount of MgO, CaO, SrO, BaO) is 20-26, a display device substrate glass ZrO ₂ is 0-4. The average linear expansion coefficient in 30-300 degreeC is 80-84 (x10 < ^-7 > / degreeC), The substrate glass for display apparatuses of Claim 1 characterized by the above-mentioned. 3. The substrate glass for a display device according to claim 1, wherein the strain point is 570 ° C. or higher. 4. The substrate glass for a display device according to claim 1, wherein a melting temperature (temperature (° C.) when the viscosity is log η = 2.0) is 1520 ° C. or less. 5. 5. The value of (working temperature (temperature when the viscosity is log η = 4.0 (° C.) − Devitrification temperature)) is 0 ° C. or more. 6. Substrate glass for display devices.