JP2001226138A - Glass substrate for flat panel display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a glass substrate for a flat panel display device which is excellent in crack resistance, generates no thermal deformation and thermal contraction even when heat-treated at 570 to 600 deg.C and has characteristics of 70 to 90×10-7/ deg.C coefficient of thermal expansion and >=10.5 Ω.cm volume electrical resistivity (log ρ). SOLUTION: The glass substrate for the flat panel display device is distinguished by having a composition (expressed by mass %) of 55 to 70% SiO2, 1 to 15% Al2O3, 0 to 15% MgO, 0 to 10% CaO, 0 to 10% SrO, 0 to 10% BaO, MgO+CaO+SrO+BaO=8 to <17%, 0 to 1.5% Li2O, 0 to 7% Na2O, 6 to 20% K2O, Li2O+Na2O+K2O=8 to 20%, 0 to 6% ZrO2 and>0.5 to 4% P2O5.

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%.
Since the temperature is as low as about 0 ° C., when heat treatment is performed at a temperature of 570 to 600 ° C., thermal deformation and thermal shrinkage occur, and the dimensions are significantly changed. It is difficult to accurately realize the plasma display device, 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 for a plasma display device having a high strain point and high volume electrical resistivity is more likely to crack in the manufacturing process 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 inventors conducted an experiment in which SiO ₂ as a basic glass component was replaced with various components. As a result, P ₂ O _5, which is known as an emulsifier for glass, was replaced with a glass substrate. To improve the crack resistance of the
The inventors have found that the volume electrical resistivity, the melting property, the moldability, and the like can be maintained at desired levels, and have proposed the present invention.

That is, the glass substrate for a flat panel display device according to the present invention has a mass percentage of SiO _{2
55~70%, Al 2 O 3 1~15} %, MgO 0~1
5%, CaO 0-10%, SrO 0-10, BaO
0-10%, MgO + CaO + SrO + BaO 8 ~
Less than 17%, Li ₂ O 0-1.5%, Na ₂ O 0-0
_{7%, K 2 O 6~20%} , Li 2 O + Na 2 O + K 2 O
_{8~20%, ZrO 2 0~6%,} P 2 O 5 0.5 Super to 4
% Of the composition.

[0010]

When replacing SiO ₂ with P ₂ O ₅ in order to improve the crack resistance of the glass substrate, the crack resistance increases as the content of P ₂ O ₅ increases. However, P ₂ O ₅ has been conventionally used in the manufacture of opalescent glass as an opacifying component of glass, and the glass eventually becomes opalescent as it is added. Therefore, in the present invention, the composition range is determined so that the transparency of the glass is not impaired even if P ₂ O ₅ is contained in the glass.

The above composition range of the present invention is regulated in consideration of density, heat shrinkage, thermal expansion coefficient, meltability and moldability in addition to crack resistance. It is as follows.

[0012] SiO ₂ is a network component of glass, but if it is less than 55%, the strain point of the glass becomes low,
Thermal deformation and thermal shrinkage are likely to occur. On the other hand, if it exceeds 70%, the glass tends to be milky, and the coefficient of thermal expansion is too small. If the coefficient of thermal expansion is too small, the difference in thermal expansion between the insulating paste and the rib paste becomes large, and the insulating paste and the rib paste are undesirably cracked or peeled off during firing. The preferred range is 56-6
8%.

Al ₂ O ₃ is a component that increases the strain point of glass. However, if it is less than 1%, the above effect cannot be obtained, and
If it exceeds 5%, the meltability deteriorates, which is not preferable. A preferred range is 4-13%, especially more than 5-13%.

MgO is a component that suppresses the opacification of glass due to the addition of P ₂ O ₅ , controls the coefficient of thermal expansion of glass, and increases the melting property and volume resistivity of glass. The more it becomes, the more easily the glass devitrifies,
It is not preferable because molding becomes difficult. The preferred range is 1
〜１０10%.

CaO is a component that increases the melting property and volume resistivity of the glass. However, if it exceeds 10%, the glass tends to be milky, which is not preferable. A preferred range is 1 to 8%. More preferably, it is in the range of 1 to less than 7%.

SrO is a component that enhances the melting property and the volume resistivity of the glass. However, if it exceeds 10%, the glass is devitrified or the density of the glass increases, so that the substrate becomes too heavy. Absent. The preferred range is 0 to
9%. More preferably, it is in the range of more than 6 to 9%.

BaO is a component that enhances the meltability and volume resistivity of the glass. However, if it exceeds 10%, the glass is devitrified or the density of the glass increases and the weight of the substrate becomes too heavy. Absent. The preferred range is 0 to
9%. More preferably, it is in the range of more than 5 to 9%.

When the content of SrO is more than 6 to 9%,
When BaO is set to 5% or less or SrO is set to 6% or less, BaO is desirably set to more than 5 to 9%.

If the total content of MgO, CaO, SrO and BaO is less than 8%, the melting property and volume resistivity of the glass decrease, and if it exceeds 17%, the crack resistance of the glass substrate is remarkably deteriorated. Absent. A preferred range for the combined amount is less than 10-17%.

Li ₂ O is a component that controls the coefficient of thermal expansion 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. A preferred range is 0-0.5%.

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. If it is more than 7%, however, the strain point of the glass decreases, which is not preferable. . A preferred range is 1-4%.

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 6%, the melting property is impaired. On the other hand, if it is more than 20%, the strain point decreases, which is not preferable. A preferred range is 6.5 to 15%, especially 8 to 15%.

When the total amount of Li ₂ O, Na ₂ O and K ₂ O is 8
%, The meltability decreases, and if it exceeds 20%, the strain point decreases, which is not preferable. Further, in order to increase the volume resistivity of the glass, Li is contained in the glass.
It is preferable to contain two or more kinds of alkali metal oxides among ₂ O, Na ₂ O and K ₂ O. A preferred range of the total amount is 10 to 17%, particularly 13 to 17%.

ZrO ₂ is a component that increases the strain point of the glass. However, if it exceeds 6%, the crack resistance of the glass is remarkably reduced, which is not preferable. The preferred range is 0 to
3%.

P ₂ O ₅ is an essential component for improving the crack resistance of the glass substrate. When the content is less than 0.5%, the above effect is not obtained. When the content is more than 4%, the volume resistivity decreases. When the plasma display device is used, the glass becomes milky and does not transmit light. A preferred range is greater than 0.5 to 2.5%.

In the present invention, in addition to the above components, 5% of TiO ₂ is added to prevent coloring by ultraviolet rays.
It is possible to add up to. Further, As ₂ O ₃ , Sb
Up to 1% of fining agents such as ₂ O ₃ , SO ₃ and Cl
Colorant components such as Fe ₂ O ₃ , CoO, NiO, Cr ₂ O ₃ , and CeO ₂ can be added up to 1% each.

In the present invention, if the glass contains B ₂ O ₃ , the glass will be opalescent. Therefore, the glass content should be suppressed to a range of up to 0.5%, and it is preferable that the glass is not contained.

The glass substrate of the present invention 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.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below.

Examples of the present invention (samples Nos. 1 to 16) are shown in Tables 1 to 4, and comparative examples (samples Nos. 17 to 20) are shown in Table 5.
Shown in In addition, sample No. 20 is a soda-lime glass.

[0031]

[Table 1]

[0032]

[Table 2]

[0033]

[Table 3]

[0034]

[Table 4]

[0035]

[Table 5]

Each sample in the table was prepared as follows.

First, glass raw materials were prepared so as to have the composition shown in the table, and were 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.

For each of the samples thus obtained, crack resistance, density, strain point, coefficient of thermal expansion, and volume resistivity were measured, and the presence or absence of milky white was observed.

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, the number of cracks generated from the four corners of the indentation by 15 seconds after unloading was counted, and the ratio to the maximum number of possible cracks (four) was determined to be the crack occurrence rate. The load at which the crack occurrence rate became 50% was defined as "crack resistance". High crack resistance means that cracks are unlikely to occur even under a high load, that is, the crack resistance is excellent.

The crack occurrence rate was measured 20 times under the same load, and the average value was obtained. The measurement was performed at a temperature of 25 ° C. and a 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.

The relationship between the crack generation rate and the content of P ₂ O ₅ will be described with reference to FIG. In FIG. 1, the vertical axis indicates the crack occurrence rate indicating the crack resistance of the glass, and the horizontal axis indicates the load applied to the diamond indenter. In the figure, A is P ₂ O ₅
, A glass substrate containing no A (sample No. 17), B having 1% of SiO ₂ having a glass composition of A replaced with P ₂ O ₅ (sample No. 1), and C having a SiO _{2 having} a glass composition of A. To P ₂
It shows a sample (Sample No. 2) substituted by 2% with O ₅ .

It can be seen that cracks tend to be less likely to occur as the content of P ₂ O ₅ increases.

Next, the characteristics of the obtained glass will be described.

As is clear from the table, the sample No. For each of samples 1 to 16, the crack resistance was 8
Since it is 80 mN or more and is equal to or more than soda lime glass, it has excellent crack resistance. The density is 2.62.
g / cm ³ or less, the strain point is 574 ° C. or more, and the volume resistivity (log ρ) is as high as 10.7 Ω · cm or more.
The coefficient of thermal expansion was in the range of 71 to 85 × 10 ⁻⁷ / ° C., and no milky white was observed.

On the other hand, the sample No. 1
As for No. 7, since P ₂ O ₅ for improving the crack resistance of the glass substrate was not contained, the crack resistance was 740 m.
N is low, and the crack resistance is inferior to those containing soda-lime glass or P ₂ O ₅ .

Sample No. With regard to No. 18, although the crack resistance was excellent, the content of P ₂ O ₅ was as high as 5.0%, so that the glass was milky and could not be used for display applications.

Sample No. As for No. 19, the content of P ₂ O ₅ was 2.0%, which was an appropriate amount and no milky whiteness occurred.
Since the total amount of O, CaO, SrO and BaO is as large as 21.3%, the crack resistance is as low as 540 mN and the crack resistance is inferior.

Sample No. As for No. 20, since it was soda-lime glass, the crack resistance was excellent at 880 mN, but the strain point was 512 ° C. and the volume electric resistivity (log ρ) was as low as 8.4 Ω · cm.

[0050]

As described above, since the glass substrate for a plasma display device of the present invention contains P ₂ O ₅ ,
Has excellent crack resistance. In addition, since the density is low, the weight of the member can be reduced, and the heat treatment at a temperature of 570 to 600 ° C. does not cause thermal deformation or thermal shrinkage.
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.

[Brief description of the drawings]

FIG. 1 is a graph showing crack resistance of glass with respect to load.

[Explanation of symbols]

A Sample No. _{17 (P 2 O 5 0%} ) B Sample No. 1 (P ₂ O ₅ 1%) C Sample No. 2 (P ₂ O ₅ 2%)

Claims (1)

[Claims] 1. The method of claim 1 wherein the weight percentage is SiO_Two 55-70
%, Al_TwoO_Three 1-15%, MgO 0-15%, Ca
O 0-10%, SrO 0-10, BaO 0-10
%, MgO + CaO + SrO + BaO 8-17% not yet
Man, Li_TwoO 0-1.5%, Na_TwoO 0-7%, K
_TwoO 6-20%, Li_TwoO + Na_TwoO + K _TwoO 8-20
%, ZrO_Two 0-6%, P_TwoO_Five More than 0.5 ~ 4%
Flat panel display characterized by having
A glass substrate for equipment.