JP2002025762A - Glass board for inorganic el display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a glass board for inorganic EL display which is to be used as back-face base board, capable of being embodied in a lightweight and small-sized construction, free of the risk of thermal deformation even if subjected to a baking process at 650-700 deg.C, and having a higher volume electric resistance than a soda lime glass board. SOLUTION: The composition of the glass board for inorganic EL display consists by mass percentage of 45-85% SiO2, 0-20% Al2O3, 0-10% MgO, 0-15% CaO, 0-15% SrO, 0-15% BaO, 0-2% Li2O, 0-15% Na2O, 0-20% K2O, 0-10% ZiO2, 0-5% B2O3, 0-5% TiO3 and 0.2-10% P2O5, and the strain point is above 520 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inorganic EL (electroluminescence) display glass substrate.

[0002]

2. Description of the Related Art Inorganic EL displays have many advantages, such as being thin and lightweight, having a clear display, and being easy to miniaturize images, thereby realizing high-quality images and being capable of full color. In the future, it is becoming more and more popular as a display device.

As shown in FIG. 1, for example, an inorganic EL display has a metal electrode 11, a first dielectric layer 12, an inorganic EL light emitting layer 13, and a second dielectric layer 1 on a rear substrate 10.
4, an ITO electrode 15, an RGB color filter 16, and a front substrate 17 are sequentially laminated.

In the inorganic EL display having such a structure, light is generated by applying a voltage to the metal electrode 11 and the ITO electrode 15 to excite the inorganic EL light emitting layer 13, and the light is generated by an RGB color filter 16. Color conversion is performed.

[0005]

In recent years, attempts have been made to use an inorganic EL display for a home television or the like, and a substrate having a size of about 40 to 60 inches is required for a large display. . Even when manufacturing a small display of 12 inches or less, it is far more productive to produce a large substrate and then cut it into multiple substrates than to produce a back substrate for each one. Therefore, the size of the substrate is desired to be increased from this point as well.

Conventionally, in the process of manufacturing an inorganic EL display, to form a dielectric layer or a phosphor layer on the rear substrate, these materials are applied to the rear substrate by a paste method or the like.
After drying, a method of firing at about 800 ° C. is employed. Therefore, an alumina substrate having high heat resistance is mainly used as the back substrate.

However, it is very difficult to produce a large substrate from alumina, and there is a problem that the cost is extremely high. Moreover, the alumina substrate has a density of 4 g / c.
Since it is as large as about m ^3, it is a major obstacle in reducing the weight of the inorganic EL display.

On the other hand, an inexpensive soda-lime glass substrate is used as the front substrate of the inorganic EL display. This glass substrate can be formed into a large plate shape and has a low density. When baking is performed, thermal deformation occurs, so that it cannot be used as a back substrate.

In recent years, the firing temperature has been lowered to reduce the production cost of inorganic EL displays.
Techniques for forming a uniform dielectric layer or luminous layer at a temperature of about 50 to 700 ° C. have been developed, and a display having a satisfactory color purity has been able to be manufactured. However, when a soda lime glass substrate is used as the rear substrate, thermal deformation also occurs.

Therefore, when an attempt is made to use a soda lime glass substrate as the rear substrate, the firing of the dielectric layer and the luminous layer is carried out by 65%.
It is necessary to perform the process at a temperature of 0 ° C. or less, that is, at a temperature at which the glass substrate does not thermally deform. However, such low-temperature baking does not provide a uniform dielectric layer or luminous layer, and the color purity of the inorganic EL display is remarkably high. It becomes worse and cannot be used.

Further, soda lime glass has a low volume electrical resistivity (log ρ) at 150 ° C. of 8.4 Ω · cm and a high mobility of alkali components in the glass. When used as
There is also a problem that an alkali component in the glass reacts with the metal electrode and changes the electric resistance of the electrode material.

The present invention has been made in view of the above circumstances, and is used as a rear substrate, does not undergo thermal deformation even when fired at 650 to 700 ° C., and has a lower volume electrical resistivity than a soda lime glass substrate. It is an object of the present invention to provide an inorganic EL display glass substrate which can be made high, lightweight and large.

[0013]

The present inventors have conducted various experiments to achieve the above object, and as a result, have obtained
It has been found that a glass substrate having a strain point of 520 ° C. or more should be used as the rear substrate in order to prevent the rear substrate from being thermally deformed in the baking process at 00 ° C., and the present invention has been proposed.

That is, the inorganic EL display gas of the present invention
The glass substrate is SiO. _Two 45-85%,
Al_TwoO_Three 0-20%, MgO 0-10%, CaO
0-15%, SrO 0-15%, BaO 0-15
%, Li_TwoO 0-2%, Na_TwoO 0-15%, K_TwoO
 0-20%, ZrO_Two 0-10%, B_TwoO_Three 0-5
%, TiO_Two 0-5%, P_TwoO_Five 0.2-10% set
Having a strain point of 520 ° C. or higher.
You.

Further, the inorganic EL display glass substrate of the present invention is characterized in that the coefficient of thermal expansion in a temperature range of 30 to 380 ° C. is 50 to 100 × 10 ⁻⁷ / ° C.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Inorganic EL display gas of the present invention
The glass substrate is SiO._Two 45-85%,
Al_TwoO_Three 0-20%, MgO 0-10%, CaO
0-15%, SrO 0-15%, BaO 0-15
%, Li_TwoO 0-2%, Na_TwoO 0-15%, K_TwoO
 0-20%, ZrO_Two 0-10%, B_TwoO_Three 0-5
%, TiO _Two 0-5%, P_TwoO_Five 0.2-10% set
Having a strain point of 520 ° C or higher (preferably 550 ° C or lower).
Above, more preferably 570 ° C. or higher).
Used as a plate, heat transforms even when fired at 650-700 ° C
No sodalime glass substrate
Has a higher volumetric electrical resistivity than that of inorganic EL displays.
The electric resistance value of the electrode material of the play is hard to change.

Further, an aluminosilicate glass substrate such as the glass substrate of the present invention has a disadvantage that it is liable to break as compared with a soda lime glass substrate, but the inorganic E glass of the present invention has a disadvantage.
Since the L display glass substrate contains 0.2% or more of P ₂ O ₅ , it has high crack resistance and is hardly broken.

Further, in the present invention, the coefficient of thermal expansion of the substrate is set to 50 to 100 in a temperature range of 30 to 380 ° C.
× 10 ^-7 / ° C (preferably 60 to 90 × 10 ^-7 / ° C)
It is more preferable that the thermal expansion coefficient is approximated to that of the front substrate or the dielectric layer, since no thermal stress is generated between the front substrate and the dielectric material.

Since such a glass substrate can be formed into a large plate, a large display substrate of 40 to 60 inches can be manufactured at a low cost. By dividing and cutting it into a plurality of pieces, a small display substrate of 12 inches or less can be manufactured at low cost.

The glass substrate of the present invention can be manufactured by a well-known sheet glass forming method, that is, a float method, a roll-out method, a slot down draw method, an overflow down draw method, or the like. It is possible to mold.

The reasons for limiting the composition of the inorganic EL display glass substrate of the present invention as described above are as follows.

SiO ₂ is a component for increasing the strain point of glass, and its content is 45 to 85%. If it is less than 45%, the strain point of the glass decreases, and thermal deformation tends to occur. On the other hand, if it is more than 85%, the thermal expansion coefficient becomes too low, which is not preferable. The preferred content of SiO ₂ is 50 to 70%.

Al ₂ O ₃ is also a component that increases the strain point of glass, and its content is 0 to 20%. If it is more than 20%, the melting property of the glass is undesirably reduced. Al
The preferable content of ₂ O ₃ is 1 to 15%.

MgO is a component that controls the coefficient of thermal expansion of glass and improves the melting property.
10%. If it is more than 10%, devitrification tends to occur, which is not preferable. The preferred content of MgO is 1-7%
It is.

CaO is a component for improving the melting property and volume electric resistance of glass, and its content is 0 to 15%.
It is. If it is more than 15%, the glass tends to be devitrified and the crack resistance is undesirably reduced. The preferred content of CaO is 1 to 10%.

SrO is a component that enhances the melting property and volume electric resistance of the glass, and its content is 0 to 15%. If it is more than 15%, the density of the glass increases and the weight of the substrate becomes too heavy, which is not preferable. The preferred content of SrO is 0 to 8%.

BaO, like SrO, is a component that increases the melting property and volume electric resistance of the glass, and its content is 0 to 15%. If it is more than 15%, the density of the glass increases and the weight of the substrate becomes too heavy, which is not preferable. The preferable content of BaO is 0 to 8%.

Li ₂ O is a component that controls the coefficient of thermal expansion of glass and enhances the meltability.
2%. If it is more than 2%, the strain point of the glass decreases, which is not preferable. The preferred content of Li ₂ O is 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, and its content is 0 to 15%. If it is more than 15%, the strain point of the glass decreases, which is not preferable. Preferred content of Na ₂ O, 0 to 6%.

K ₂ O, like Li ₂ O and Na ₂ O, is a component that controls the coefficient of thermal expansion of glass and enhances the melting property, and its content is 0 to 20%. If it is more than 20%, the strain point of the glass decreases, which is not preferable. K ₂ O
Is preferably 4 to 15%.

ZrO ₂ is a component for increasing the strain point of glass, and its content is 0 to 10%. If it is more than 10%, the crack resistance of the glass is significantly reduced, and
It is not preferable because the density of the glass increases and the weight of the substrate increases. The preferable content of ZrO ₂ is 0 to 5%.
It is.

B ₂ O ₃ is a component for improving the melting property of glass, and its content is 0 to 5%. If it is more than 5%, the strain point of the glass decreases, which is not preferable. B ₂ O ₃
Is preferably 0 to 2%.

TiO ₂ is a component that improves the chemical durability of the glass and prevents the glass from being colored by ultraviolet rays, and its content is 0 to 5%. If it is more than 5%, the density of the glass increases and the weight of the substrate becomes too large. The preferred content of TiO ₂ is 0 to 1%.

P ₂ O ₅ is a component for improving the crack resistance of the glass substrate, and its content is 0.2 to 10%. If it is less than 0.2, the effect of increasing the crack resistance is small, and if it is more than 10%, the volume electric resistivity decreases, which is not preferable. The preferred content of P ₂ O ₅ is 0.
5 to 3%.

In the present invention, in addition to the above components,
A fining agent such as s ₂ O ₃ , Sb ₂ O ₃ , SO ₃ , and Cl is added in a total amount of 1
%, Fe ₂ O ₃ , CoO, NiO, Cr ₂ O ₃ , CeO
Colorants such as ₂ can each contain up to 1%.

However, considering the environmental aspect, harmful As ₂ O ₃
Should be avoided and large amounts of Na
_{When 2} O and K ₂ O are contained, alkali ions in the glass are diffused into the dielectric layer and the like at the time of sintering, and characteristics are likely to be degraded. Therefore, the total amount of Na ₂ O and K ₂ O is set to 20 mass%. % Is desirable.

Furthermore, in the present invention, the lower the density of the glass substrate, the more the inorganic EL display can be reduced in weight. Therefore, the density is preferably 3.0 g / cm ³ or less (preferably 2.8 g / cm ³ ). ³ or less).

[0038]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following, the inorganic EL display glass substrate of the present invention will be described in detail based on embodiments.

Tables 1 and 2 show examples (samples Nos. 1 to 9) and comparative examples (samples Nos. 10 and 11) of the inorganic EL display glass substrate of the present invention. In addition, No. which is a comparative example. The sample No. 11 is a soda-lime glass substrate which is commercially available as architectural window glass.

[0040]

[Table 1]

[0041]

[Table 2]

No. in the table. Each of the samples 1 to 10 was produced as follows.

Glass raw materials were prepared so as to have the respective glass compositions shown in the table, melted in a platinum pot at 1550 ° C. for 5 hours, and then poured out onto a carbon plate to prepare a glass substrate.

Various characteristics of the thus obtained samples were evaluated, and the results are shown in the table.

As is clear from the table, the N
o. Each of samples 1 to 10 has a strain point of 558 ° C. or more, a volume resistivity of 10.6 or more, a crack resistance of 600 mN or more, a thermal expansion coefficient of 73 to 85 × 10 ⁻⁷ / ° C., and an inorganic EL display. It was suitable as a back substrate. In addition, since each of these samples has a low density, the weight can be reduced.

On the other hand, the comparative example No. Since the sample No. 10 has a low crack resistance of 440 mN, it is considered that cracks are likely to occur in the manufacturing process.

No. Since the sample No. 11 has a low strain point, when it is used as a back substrate of an inorganic EL display and baked at 650 to 700 ° C., it is considered that thermal deformation occurs. Further, since the volume electric resistivity is as low as 8.5, it is considered that the electric resistance value of the electrode material is changed.

The strain points in the table are based on ASTM C336-
And measured according to ASTM 71
The value at 150 ° C. was measured based on C657-78.

The crack resistance is determined by the method proposed by Wada et al. (M. Wada et al. Proc., The
Xth ICG, vol. 11, Ceram. So
c. , Japan, Kyoto, 1974, p39). In this method, a sample glass is placed on the 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. And
After unloading, the number of cracks generated from the four corners of the indentation by 15 seconds is counted, the ratio to the maximum number of possible cracks (4) is calculated, the number of cracks is counted, and the maximum number of cracks (4 ) Is determined and defined as the crack occurrence rate. The load at which the crack occurrence rate becomes 50% is 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 conditions were: air temperature 25 ° C
The test was performed under the condition of a humidity of 30%.

Further, the average coefficient of thermal expansion was measured at 30 to 380 ° C. using a dilatometer. The density was measured by the well-known Archimedes method.

[0051]

As described above, the inorganic EL display glass substrate of the present invention has a high strain point of 520 ° C. or higher, and
Because of its high volume resistivity and crack resistance, it is suitable as a back substrate of an inorganic EL display.

Further, since the inorganic EL display glass substrate of the present invention has a low density, the weight can be reduced, and a large-sized substrate can be manufactured at low cost.
It is possible to manufacture large home televisions of 40 to 60 inches, and when used for small displays, the productivity is greatly improved.

Further, the coefficient of thermal expansion of the inorganic EL display glass substrate of the present invention is set to 5 in a temperature range of 30 to 380 ° C.
When the temperature is set to 0 to 100 × 10 ⁻⁷ / ° C., there is an advantage that thermal stress is hardly generated between the front substrate and the dielectric material.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a structure of an inorganic EL display.

DESCRIPTION OF SYMBOLS 10 Back substrate 11 Metal electrode 12 First dielectric layer 13 Inorganic EL light emitting layer 14 Second dielectric layer 15 ITO electrode 16 RGB color filter 17 Front substrate

 ──────────────────────────────────────────────────続 き Continued from the front page F term (reference) EE03 EE04 EF01 EF02 EF03 EF04 EG01 EG02 EG03 EG04 FA01 FA10 FB01 FB02 FB03 FC01 FC02 FC03 FD01 FE01 FF01 FG01 FH01 FJ01 FK01 FL01 GA01 GA10 GB01 GC01 GD01 GE01 HH01 HH HH HH HH HH HH HH HH HH HH HH KK07 KK10 MM27 NN26 NN29

Claims (2)

[Claims] 1. The composition according to claim 1, wherein the mass percentage is SiO ₂ 45-85.
_{%, Al 2 O 3 0~20%} , 0~10% MgO, Ca
O 0-15%, SrO 0-15%, BaO 0-15
_{%, Li 2 O 0~2%,} Na 2 O 0~15%, K 2 O
_{0~20%, ZrO 2 0~10%,} B 2 O 3 0~5
%, TiO ₂ 0 to 5%, P ₂ O ₅ 0.2 to 10%, and a strain point of 520 ° C. or more. 2. The inorganic EL display substrate according to claim 1, wherein a coefficient of thermal expansion in a temperature range of 30 to 380 ° C. is 50 to 100 × 10 ⁻⁷ / ° C.