JP2008214166A - Substrate glass for display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a glass composition suitable for a glass substrate having an appropriate coefficient of thermal expansion, a low melting point, a high distortion point, and high heat resistance, for example, a substrate for an electronic display, such as PDP (plasma display panel). <P>SOLUTION: A substrate glass for a display device comprises, by weight, 57-62% SiO<SB>2</SB>, 4-7% Al<SB>2</SB>O<SB>3</SB>, 2-5% ZrO<SB>2</SB>, 2-6 Na<SB>2</SB>O, 4-9% K<SB>2</SB>O, 0-4% MgO, 4-9% CaO, 6-9% SrO, 6-14% BaO, and 0.1-1.0% HfO<SB>2</SB>, with the proviso that the total amount of Na<SB>2</SB>O and K<SB>2</SB>O is 9-14% and the total amount of MgO, CaO, SrO, and BaO is 17-25%, and has an average coefficient of linear thermal expansion of 80-87(×10<SP>-7</SP>/°C) within a range of 30-300°C and a distortion point of 560-580°C. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a glass composition suitable for production by float molding, and particularly suitable for a substrate for an electronic display such as a PDP (plasma display panel) such as a glass substrate that requires an appropriate thermal expansion coefficient and a high strain point. .

  Conventionally, in the field of PDP production, glass shaped into a plate shape by a float process, particularly alkali, alkaline earth, and silica glass similar to soda lime silica glass has been used. Since the glass is suitable for mass production and excellent in smoothness, it is particularly suitable for an electronic display substrate such as a PDP.

  However, an electronic display substrate typified by PDP has a step of firing a metal electrode, an insulating paste, a rib paste, etc. on the substrate, and a normal soda-lime silica glass has a strain point of about 500 ° C. There was a problem that the substrate was deformed in the process and the electrode position was shifted. Moreover, in order to prevent a positional shift with respect to a peripheral member, a board | substrate with a small thermal expansion coefficient difference with them is calculated | required.

In order to solve these problems, high strain point glass having a strain point exceeding 550 ° C. and having an adjusted average thermal expansion coefficient are disclosed (see Patent Documents 1 to 5).
Japanese Patent No. 2738036 Japanese Patent No. 3669022 Japanese Patent No. 3770670 Japanese Patent No. 3666054 Japanese Patent No. 3460298

  However, since all of the materials described in the above publication contain 10 wt% or more of alkali oxides in order to match the desired thermal behavior, the problem is that alkali ions move to the electrode side during the heat treatment process and color the glass. was there. Of course, the coloring of the glass substrate is undesirable because it causes a deterioration in the image quality of the display panel.

  In order to prevent coloring problems, it is generally considered to reduce the content of alkali oxides, but changes in the glass composition that change the thermal behavior in the substrate glass for display are not acceptable.

  Therefore, in the present invention, in order to solve such a problem, it is possible to suppress the amount of alkali elution without changing the thermal behavior by focusing on a slight amount of components contained in the glass and optimizing this. I found out.

The present invention is expressed in weight%,
_{SiO 2 57~62, Al 2 O 3} 4~7, ZrO 2 2~5, Na 2 O 2~6, K 2 O 4~9, MgO 0~4, CaO 4~9, SrO 6~9, BaO 6-14, HfO ₂ 0.1-1.0,
And a display device substrate glass, wherein the Na ₂ O and _{K 2} O in the total amount 9 to 14, MgO, CaO, SrO, BaO of the total amount 17 to 25, a.

Further, the substrate glass for a display device described above, which contains 0.1 to 1.0 of Rb ₂ O in terms of% by weight.

  Further, the substrate glass for a display device described above, wherein the alkali elution amount based on JIS R3502 is less than 0.1 mg.

  Moreover, it is said substrate glass for display apparatuses characterized by a strain point being 560 degreeC-580 degreeC.

Furthermore, the average linear expansion coefficient in 30-300 degreeC is 80-87 (x10 < ^-7 > / degreeC), It is said substrate glass for display apparatuses characterized by the above-mentioned.

  The glass of the present invention not only has an appropriate thermal expansion coefficient and a high strain point, which has improved the problems for display substrates, particularly PDPs, but also suppresses alkali elution, which was a major problem with display substrates.

The present invention is expressed in weight%,
_{SiO 2 57~62, Al 2 O 3} 4~7, ZrO 2 2~5, Na 2 O 2~6, K 2 O 4~9, MgO 0~4, CaO 4~9, SrO 6~9, BaO 6-14, HfO ₂ 0.1-1.0,
And a display device substrate glass, wherein the Na ₂ O and _{K 2} O in the total amount 9 to 14, MgO, CaO, SrO, BaO of the total amount 17 to 25, a.

SiO ₂ is a main component of glass, and if it is less than 57% by weight, the heat resistance or chemical durability of the glass is deteriorated. On the other hand, if it exceeds 62%, the high-temperature viscosity of the glass melt increases, making glass molding difficult. 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 57 to 62%.

Al ₂ O ₃ has the effect of increasing the strain point and decreasing the density. If it is less than 4%, this effect cannot be obtained. If it exceeds 7%, the tendency of devitrification of the glass increases, and it becomes difficult to mold molten glass. Accordingly, the range is 4 to 7%, preferably 4 to 6%.

Na ₂ O, together with K ₂ O, increases the coefficient of thermal expansion of the glass and acts as a flux during melting of the glass. If it exceeds 6%, the coefficient of thermal expansion becomes too large, which is unsuitable. If it is less than 2%, the high-temperature viscosity of the glass melt becomes high and glass molding becomes difficult. Therefore, the range is 2 to 6%.

K ₂ O exhibits the same effect as Na ₂ O. If it exceeds 9%, the thermal expansion coefficient becomes too large, and if it is less than 4%, the high-temperature viscosity of the glass melt increases, so the range is 4-9%.

With respect to the amount of the alkali component (Na ₂ O, K ₂ O), the linear thermal expansion coefficient, high temperature viscosity and devitrification temperature can be maintained in appropriate ranges by setting the total amount to 9 to 14%. . If the total amount of alkali components is less than 9%, the high-temperature viscosity of the glass melt becomes high, and glass molding becomes difficult. Further, the tendency of glass to devitrify increases. If it exceeds 14%, the thermal expansion coefficient increases excessively. Therefore, the range is 9 to 14%.

  MgO is not an essential component but has the effect of increasing the strain point of the glass when contained. However, if it exceeds 4%, the devitrification temperature of the glass cannot be maintained in an appropriate range, and it becomes difficult to mold the molten glass. Therefore, the range is 0 to 4%. More desirably, it is 1 to 3%.

  CaO has an effect of increasing the strain point of the glass and decreasing the viscosity of the molten glass when the glass is melted. If it is less than 4%, the heat resistance of the glass is deteriorated. On the other hand, if it exceeds 9%, the tendency of devitrification increases, and it becomes difficult to mold molten glass. Therefore, the range is 4 to 9%.

  SrO has the effect of improving the durability and devitrification resistance of glass. If it is less than 6%, this effect is small. On the other hand, if it exceeds 9%, the tendency of devitrification of the glass becomes large, and it becomes difficult to mold molten glass. Therefore, the range is 6 to 9%.

  BaO has an effect of suppressing the devitrification tendency of the glass melt and also acts as a flux during glass melting. If it is less than 6%, the high-temperature viscosity of the glass melt becomes high and glass molding becomes difficult. However, if it exceeds 14%, the tendency of devitrification of the glass increases, and it becomes difficult to mold the molten glass. More desirably, it is 8 to 12% of range.

  Further, within the above composition range, the total amount of the divalent metal oxide RO (R is Mg, Ca, Sr, Ba) is in the range of 17 to 25%, thereby improving the melting property of the glass. While maintaining the above, it is possible to obtain a glass having a suitable viscosity-temperature gradient, good glass moldability, excellent heat resistance, chemical durability, etc., and having an appropriate range of thermal expansion coefficient. If the total RO is less than 17%, the high-temperature viscosity increases and it becomes 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 25%, the density increases, the tendency to devitrification increases, and the chemical durability decreases.

ZrO ₂ has the effect of raising the strain point of the glass and improving the chemical durability of the glass. If it is less than 2%, the heat resistance of the glass deteriorates, and improvement in chemical durability cannot be expected. On the other hand, if it exceeds 5%, the density increases and the tendency to devitrification increases, so that it becomes difficult to form glass. Therefore, the range is 2 to 5%.

HfO ₂ has the effect of increasing the strain point of glass and improving the chemical durability of glass, like ZrO ₂ , but has the effect of suppressing alkali elution particularly when contained in a trace amount. If it is less than 0.1% or 1.0% or more, the effect is not sufficiently exhibited, so the range is made 0.1 to 1.0%.

Further, Rb ₂ O has a function of suppressing alkali elution by containing a trace amount in the same manner as HfO ₂ . If it is less than 0.1%, the effect is not sufficiently exhibited. Moreover, when it contains abundantly, it has the property of reducing the strain point of glass. For this reason, it is desirable that it is 0.1 to 1.0% of range.

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 contain NiO, etc. up to 1% in total. Further, in order to prevent electron beam browning in the PDP, TiO ₂ and CeO ₂ may each be contained up to 1%, and the total amount may be contained up to 1%.

The present invention also provides the above substrate glass for a display device, wherein the alkali elution amount based on JIS R3502 is less than 0.1 mg. The alkali elution amount can be reduced by the effects of the above HfO ₂ and Rb ₂ O, but it is possible to suppress the coloring of the glass particularly by setting it to less than 0.1 mg.

  Moreover, it is said substrate glass for display apparatuses characterized by a strain point being 560 degreeC-580 degreeC. The strain point is a characteristic showing the heat resistance of glass. In a display panel, the strain point should be high as long as other properties are not impaired. Therefore, 560 ° C. or higher is appropriate. However, when glass is formed by a float method or the like, if the strain point is too high, the molding becomes difficult. In the composition range of the present invention, there is also an upper limit of the strain point. Therefore, the upper limit was set to 580 ° C.

Furthermore, the average linear expansion coefficient in 30-300 degreeC is 80-87 (x10 < ^-7 > / degreeC), It is said substrate glass for display apparatuses characterized by the above-mentioned. The coefficient of thermal expansion is also a characteristic showing the heat resistance of glass, and if it exceeds 87 × 10 ⁻⁷ / ° C., it is unsuitable because thermal deformation becomes too large in the manufacturing process of the display panel, and 80 to 87 × 10 ⁻⁷ / Outside the range of ° C., the amount of deformation differs from other members, which is not preferable.

  Hereinafter, a description will be given based on examples.

(Creation of glass)
A platinum crucible is filled with a blended raw material consisting of silica sand, aluminum oxide, sodium carbonate, sodium sulfate, potassium carbonate, magnesium oxide, calcium carbonate, strontium carbonate, barium carbonate, zirconium silicate, hafnium oxide and rubidium oxide, and 1500 in an electric furnace. It was heated and melted at ˜1600 ° C. for about 6 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. The amounts of HfO ₂ and Rb ₂ O, which are trace components, were confirmed with an ICP emission spectroscopic analyzer Optima5300DV (manufactured by PerkinElmer Co., Ltd.). About these glass, the alkali elution amount, the average linear expansion coefficient of 30-300 degreeC, and the strain point were measured with the following method.

  The alkali elution amount was measured based on the provisions of JIS R3502. The expansion coefficient was determined by measuring the average linear expansion coefficient at 30 to 300 ° C. using a thermomechanical analyzer TMA8310 (manufactured by Rigaku Corporation). The strain point was measured by a beam bending method based on JIS R3103-2.

(result)
Examples in Table 1 are glasses in the present invention, and Comparative Example 1 is a glass not containing HfO ₂ and Rb ₂ O. In Comparative Example 1, the alkali elution amount is as large as 0.15 mg. When HfO ₂ was added sequentially as in Examples 1 to 3, the alkali elution amount in Example 1 was 0.05, indicating a minimum value. This behavior is shown in FIG. Also, the case further went successively added Rb 2 _O to the first embodiment shown in Examples 4-6, it can be seen that there is a similarly suppress the effect of the amount of alkali elution. Further, in the examples, the physical properties (strain point, thermal expansion coefficient of 30 to 300 ° C.) relating to the thermal behavior of the glass are not significantly changed, and the glass capable of suppressing the alkali elution amount without changing the thermal behavior of the glass. Was invented.

  If the glass according to the present invention is used, it is apparent that coloring during heat treatment hardly occurs while having the heat resistance of the conventional display substrate glass.

  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.

In the present invention, it is a diagram showing the relationship HfO ₂ amount and the amount of alkali elution.

Claims (5)

In weight% display
SiO ₂ 57~62,
Al ₂ O ₃ 4-7,
ZrO ₂ 2-5,
Na ₂ O 2-6,
K ₂ O 4-9,
MgO 0-4,
CaO 4-9,
SrO 6-9,
BaO 6-14,
HfO ₂ 0.1-1.0,
And,
Total amount of Na ₂ O and K ₂ O 9-14,
Total amount of MgO, CaO, SrO and BaO 17-25,
A substrate glass for a display device. The substrate glass for a display device according to claim 1, which contains 0.1 to 1.0 of Rb ₂ O in terms of% by weight. The substrate glass for a display device according to claim 1 or 2, wherein the alkali elution amount based on JIS R3502 is less than 0.1 mg. 4. The substrate glass for a display device according to claim 1, wherein the strain point is 560 ° C. to 580 ° C. 5. The average linear expansion coefficient in 30-300 degreeC is 80-87 (x10 < ^-7 > / degreeC), The substrate glass for display apparatuses of any one of Claims 1 thru | or 4 characterized by the above-mentioned.

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