JP2001247332A - Glass plate for flat panel displaying unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a glass plate for a flat panel displaying unit excellent in crack resistance, not forming thermal deformation or heat shrinkage even on heat-treating at a temperature of 570-600 deg.C, and also having characteristics of 70-90×10-7/ deg.C thermal expansion coefficient and >=10.5 Ω.cm volume electric resistivity (log ρ). SOLUTION: This glass plate is characterized by having a composition in mass % of 55-70% SiO2, >5-<10% Al2O3, 0-7% MgO, 0-10% CaO, 0-<9% SrO, 0-<9% BaO, 0-1.5% Li2O, 0-5% Na2O, 5-16% K2O, 0.3-5% ZrO, 4-<9% SrO+ BaO, 8-<17% MgO+CaO+SrO+BaO and 6-18% Li2O+Na2O+K2O, and also having the value of CaO/MgO is in the range of 0.10-1.48 in mass ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat panel display device, and more particularly to a glass substrate for a plasma display device.

[0002]

2. Description of the Related Art In a plasma display device, a transparent electrode and a dielectric paste, such as an ITO film and a Nesa film, are generally provided on the surface of a front glass substrate, and A
A circuit is formed by applying an electrode made of l, Ag, and Ni and a rib paste and baking at a temperature of about 500 to 600 ° C., and thereafter, the front glass substrate and the back glass substrate are opposed to each other, and the periphery is 500 to 600 ° C. It is manufactured by frit sealing at a temperature of about 600 ° C. Conventionally, as a glass substrate, soda-lime glass (coefficient of thermal expansion of about 84 × 10
⁻⁷ / ° C.). In addition, the thermal expansion coefficient of peripheral materials such as insulating paste, rib paste, and frit seal is 70 to 90 in accordance with soda-lime glass.
It is adjusted to the range of × 10 ^-7 / ° C.

[0003] However, soda-lime glass has a strain point of 50%.
When the heat treatment is performed at a temperature of 570 to 600 ° C., which is as low as about 0 ° C., thermal deformation and thermal shrinkage occur, and the dimensions are significantly changed. It is difficult to realize the plasma display device with high accuracy, and it has been particularly difficult to manufacture a large-sized, high-definition plasma display device.

[0004] Soda lime glass has a low volume electrical resistivity (log ρ) at 150 ° C of 8.4 Ω · cm, and has a high mobility of alkali components in the glass. Therefore, there is also a problem that an alkali component in the glass reacts with a thin film electrode such as an ITO film or a Nesa film to change the electric resistance value of the electrode material.

[0005] From these circumstances, thermal deformation of the glass substrate,
In order to solve the problems of heat shrinkage and volume resistivity, glass substrates for plasma display devices having a thermal expansion coefficient equivalent to that of soda-lime glass, a high strain point and a high volume resistivity have been proposed. Large and high-definition plasma display devices have been manufactured using these glass substrates.

[0006]

However, the above-mentioned conventional glass substrate having a high strain point and high volume electrical resistivity is more likely to be cracked in the manufacturing process of the plasma display device than soda-lime glass. For this reason, the yield of the apparatus is low, which is one of the causes that hinders improvement in productivity. Therefore, in order to improve the productivity, it is necessary to make the glass substrate hard to break. That is, a glass substrate having high crack resistance is desired.

[0007] An object of the present invention is to provide excellent crack resistance.
Even when heat-treated at a temperature of 70 to 600 ° C., no thermal deformation or thermal contraction occurs, and the coefficient of thermal expansion is 70 to 90 × 10 ⁻⁷ /
° C, volume resistivity (log ρ) is 10.5Ω · cm
An object of the present invention is to provide a glass substrate for a flat panel display device having the above characteristics.

[0008]

The present inventor conducted an experiment in which the basic glass component, SiO _2, was replaced with various components. As a result, alkaline earth metal oxides (MgO, CaO, S
It has been found that when rO, BaO) and ZrO ₂ satisfy the following conditions, the crack resistance of the glass substrate is improved.
Keep the total amount of alkaline earth metal oxides low. Among the alkaline earth metal oxides, the content of CaO is particularly reduced. Keep the ZrO ₂ content low.

However, if the content of these components is too low, the strain point, the volume electrical resistivity, the melting property and the moldability are remarkably deteriorated. Therefore, the present inventor has found that by appropriately setting the contents of the alkaline earth metal oxide and ZrO ₂ , a glass substrate having high crack resistance can be obtained while maintaining the above characteristics. It is proposed as an invention.

That is, the glass substrate for a flat panel display device of the present invention has a SiO ₂ content of 55
70%, Al ₂ O ₃ less than 5 percent to 10%, MgO 0 to
7%, CaO 0-10%, SrO 0-9%, B
aO 0 to less than 9%, Li ₂ O 0 to 1.5%, Na ₂
O 0-5%, K ₂ O 5-16%, ZrO ₂ 0.3-
5%, SrO + BaO 4 to less than 9%, MgO + CaO
+ SrO + BaO 8 to less than 17%, Li ₂ O + Na ₂ O +
K ₂ O having a composition of 6 to 18% and CaO / MgO
Is in the range of 0.10 to 1.48 by mass ratio.

[0011]

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

[0012] SiO ₂ is a glass network former, but if it is less than 55%, the strain point of the glass decreases, and thermal deformation and thermal shrinkage tend to occur. on the other hand,
If it exceeds 70%, the thermal expansion coefficient of the glass becomes too small. If the coefficient of thermal expansion is too small, the difference in thermal expansion between the insulating (dielectric) material and the rib material becomes large, and the insulating layer and the rib are undesirably cracked or peeled off during firing.
The preferred range of SiO ₂ is 56 to 68%.

Al ₂ O ₃ is a component that increases the strain point of glass. However, if the content is less than 5%, the above effect cannot be obtained. If the content is more than 10%, the volume electric resistance decreases and the meltability deteriorates. Not preferred. The preferred range of Al ₂ O ₃ is 5%.
Ultra-9.5%. More preferably, it is 5.1 to 9%.

MgO is a component that controls the coefficient of thermal expansion of the glass and enhances the melting property of the glass. However, if it exceeds 7%, the glass tends to be devitrified, and molding is difficult. The preferred range of MgO is 1-5%.

[0015] CaO is a component that enhances the melting property of the glass, but if it exceeds 10%, the crack resistance of the glass is significantly reduced, which is not preferable. The preferred range of CaO is 1 to 5%. More preferably, it is 1 to 4%.

On the other hand, if the value of CaO / MgO is less than 0.10, the viscosity at high temperature becomes high, the melting property is deteriorated, and the strain point is lowered. On the other hand, when this value exceeds 1.48, crack resistance is significantly deteriorated. A preferred range of the value of CaO / MgO is 0.20 to 1.35.

SrO is a component that enhances the melting property and volume resistivity of glass. However, when the content is 8.5% or more, particularly 9% or more, the glass is devitrified or the density of the glass is increased to increase the density of the substrate. It is not preferable because the weight becomes too heavy. The preferred range of SrO varies depending on the content of BaO, and is 0 to 3% when BaO is more than 5% to less than 9%, and is more than 6% to less than 9% when BaO is 0 to 3%. .

BaO, like SrO, is a component that enhances the melting property and volume resistivity of glass. However, when it is 8.5% or more, especially 9% or more, the glass is devitrified or the glass density is increased. As a result, the weight of the substrate becomes too heavy, which is not preferable. The preferable range of BaO varies depending on the content of SrO, and 0% when SrO is more than 6% to less than 9%.
３3%, when SrO is 0９3%, more than 5 %％ 9%
Is less than.

If the total amount of SrO and BaO is less than 4%, the electric resistance decreases, and if it exceeds 9%, the crack resistance decreases. The total amount of SrO and BaO is preferably in the range of 5 to 8%.

When the total amount of MgO, CaO, SrO and BaO is less than 8%, the melting property of the glass decreases,
If it exceeds 17%, the crack resistance of the glass substrate is significantly reduced. The total amount of these components is preferably 10 to 16%.

Li ₂ O is a component that controls the thermal expansion coefficient of glass and enhances the melting property of glass.
If the number is too large, the strain point of the glass is lowered, and heat deformation or heat shrinkage is likely to occur in a heat treatment step when manufacturing a plasma display device, which is not preferable. Li ₂ O
Is preferably 0 to 1%.

Na ₂ O, like Li ₂ O, is a component that controls the thermal expansion coefficient of the glass and enhances the melting property of the glass. However, if it exceeds 5%, the strain point of the glass decreases, which is not preferable. . The preferred range of Na ₂ O is 0.5 to
5%. More preferably, it is 1 to 4%.

K ₂ O, like Li ₂ O and Na ₂ O, is a component that controls the coefficient of thermal expansion of the glass and enhances the melting property of the glass. However, if it is less than 5%, the melting property is impaired. On the other hand, if it exceeds 16%, the strain point decreases, which is not preferable. The preferred range of K ₂ O is 6 to 15%.
It is.

When the total amount of Li ₂ O, Na ₂ O and K ₂ O is less than 6%, the meltability decreases, and when the total amount exceeds 18%, the strain point decreases, which is not preferable. Further, in order to increase the volume resistivity of the glass, Li ₂ is contained in the glass.
It is preferable to contain two or more kinds of alkali metal oxides among O, Na ₂ O and K ₂ O. The total amount of these components is preferably in the range of 8 to 17%.

ZrO ₂ is a component that increases the strain point of the glass. However, if it is less than 0.3%, its effect is not obtained, and if it is more than 5%, the crack resistance of the glass is remarkably deteriorated, which is not preferable. The preferred range of ZrO ₂ is 0.3
~ 3%. More preferably, it is 0.3 to 1%.

In the present invention, various components can be added in addition to the above components. For example, it is possible to add TiO _{2 up} to 5% in order to prevent coloring by ultraviolet rays, and up to 4% P ₂ O _{5 in} order to improve crack resistance. Further, As ₂ O ₃ , Sb ₂ O ₃ , SO ₃ , C
l to 1% in total of Fe ₂ O ₃ , Co
O, NiO, Cr ₂ O ₃ , CeO _2, etc.
% Can be added.

The glass substrate of the present invention having the above composition can be manufactured by a method such as a float method, a fusion method, or a roll-out method, which is known as a method for forming a sheet glass.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments.

Examples of the present invention (samples Nos. 1 to 8) are shown in Tables 1 and 2, and comparative examples (samples Nos. 9 to 16) are shown in Tables 3 and 4. In addition, sample No. 16 is a soda-lime glass.

[0030]

[Table 1]

[0031]

[Table 2]

[0032]

[Table 3]

[0033]

[Table 4]

Each sample in the table was prepared as follows.

First, a glass raw material was prepared so as to have the composition shown in the table, and was melted in a platinum pot at 1450 to 1600 ° C. for 4 hours. Thereafter, the molten glass is poured out onto a carbon plate, formed into a plate shape, cooled slowly, and 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. The sample glass was produced by processing.

The samples thus obtained were measured for crack resistance, density, strain point, coefficient of thermal expansion, and volume resistivity, and the results are shown in the table.

In the present invention, the evaluation of the crack resistance of the glass is performed by the method proposed by Wada et al. (M. Wada et a).
l. Proc. , The Xth ICG, vo
l. 11, Ceram. Soc. , Japan,
(Kyoto, 1974, p39) was used. In this method, a sample glass is placed on a stage of a Vickers hardness tester, and a diamond-shaped diamond indenter is pressed against the surface of the sample glass with various loads for 15 seconds. Then, by 15 seconds after unloading, the number of cracks generated from the four corners of the indentation is counted, and the ratio to the maximum number of possible cracks (four) is determined to be the crack occurrence rate. In this evaluation, the crack occurrence rate under the same load was measured 20 times, and the average value was defined as the crack occurrence rate. In this way, the load at which the crack occurrence rate becomes 50% is referred to as "crack resistance",
This value is shown in the table. High crack resistance means that cracks are unlikely to occur even under a high load, that is, the crack resistance is excellent. Since the crack resistance is affected by humidity, the measurement was performed at a temperature of 25 ° C.
The test was performed under the condition of humidity of 30%.

The density was measured by the well-known Archimedes method, and the strain point was measured based on ASTM C336-71. For the coefficient of thermal expansion, the average coefficient of thermal expansion at 30 to 380 ° C.
ASTM C657-78 for volume resistivity
The value at 150 ° C. was measured based on. The presence or absence of milky white was visually observed after the glass was gradually cooled.

As is clear from the table, the sample No. Each of the samples 1 to 8 has a crack resistance of 850 mN or more, which is equal to or more than that of soda-lime glass, and is excellent in crack resistance. The density is 2.56
g / cm ³ or less, the strain point is 573 ° C. or more, and the volume resistivity (log ρ) is as high as 10.9 Ω · cm or more.
The coefficient of thermal expansion was in the range of 79 to 85 × 10 ⁻⁷ / ° C.

On the other hand, the sample No. 9
Has a low strain point because Al ₂ O ₃ is 5% or less.
Sample No. In No. 10, the electric resistance was low because Al ₂ O ₃ was 10% or more. Sample No. Sample No. 11 had a low strain point because ZrO ₂ was less than 0.3%. Sample No.
In No. 12, the electric resistance was low because the total amount of SrO and BaO was less than 4%. Sample No. 13 is SrO and Ba
Crack resistance was low because the total amount of O was 9% or more. Sample No. In No. 14, the strain point was low because the value of CaO / MgO was less than 0.1. Sample No. 15 is C
Since the value of aO / MgO was larger than 1.48, the crack resistance was low.

[0041]

As described above, the glass substrate for a plasma display device of the present invention has excellent crack resistance. In addition, since the strain point is high, thermal deformation or thermal shrinkage does not occur in a heat treatment at a temperature of 570 to 600 ° C. And 70-90
Since it has a coefficient of thermal expansion of × 10 ^-7 / ° C and a high volume resistivity, it is suitable as a glass substrate for flat panel display devices, particularly plasma display devices.

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Claims (3)

[Claims] 1 to 55 to 70% by weight of SiO ₂ ,
Al ₂ O _{3 More} than 5% to less than 10%, MgO 0 to 7%, C
aO 0 to 10%, SrO 0 to less than 9%, BaO 0
９9%, Li ₂ O 0-1.5%, Na ₂ O 0-
_{5%, K 2 O5~16%,} ZrO 2 0.3~5%, Sr
O + BaO 4 to less than 9%, MgO + CaO + SrO +
BaO less than _{8~17%, Li 2 O + Na} 2 O + K 2 O
A glass substrate for a flat panel display device, wherein the glass substrate has a composition of 6 to 18% and the value of CaO / MgO is in the range of 0.10 to 1.48 by mass ratio. 2. The method according to claim 1, wherein SrO is more than 6% to less than 9% and BaO is 0 to 3% by mass percentage.
Glass substrates for flat panel display devices. 3. SrO 0 to 3% by mass percentage, BaO
The glass substrate for a flat panel display device according to claim 1, wherein the glass substrate is more than 5% to less than 9%.