JPH11335133A - Substrate glass for display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a glass with thermal expansion coefficient and specific gravity approximate to those of soda lime-based glass and strain point higher than that of soda lime-based glass, suitable in the form of a substrate for display devices. SOLUTION: This substrate glass for display devices, with a strain point of >=580 deg.C, thermal expansion coefficient of 75 to 85×10-7 / deg.C at room temperature to 300 deg.C and specific gravity of <=2.55, has such a composition as to be 61-66 wt.% SiO2 , 8-14 wt.% Al2 O3 , 70-77 wt.% SiO2 +Al2 O3 , 1-6 wt.% MgO, 4-8 wt.% CaO, 1-5.5 wt.% SrO, 9-13 wt.% MgO+CaO+SrO, 0-3 wt.% Li2 O, 3-8 wt.% Na2 O, 5-8 K2 O, 9-13 wt.% Li2 O+Na2 O+K2 O, and 0.03-0.2 wt.% SO3 .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate glass for various display devices, and particularly to a plasma display panel (PDP).
The present invention relates to a glass suitable for a substrate glass for a display, which is easy to be formed by melting including an electric melting method and forming (plate making) by a float method.

[0002]

In BACKGROUND OF problem to be solved, for example PDP manufacturing field, the conventional thermal expansion coefficient at room temperature ~ 300 ° C. as the substrate glass is 80-90 × 10 ^{over 7} / ° C. approximately, the strain point is 510 to 520 ° C.
Some soda-lime glass has been employed. However, since the strain point is low, the substrate glass is likely to warp or undulate when performing various heat treatments on panel manufacturing, such as arranging an electrode wire pattern on it and further forming an insulating coating with low melting point glass. Having.

[0003] In order to solve the above-mentioned problems, in recent years, there have been scattered proposals for substrate glass having a higher strain point than soda-lime glass. However, the specific gravity of glass is generally higher than 2.7, and especially P
In DP, it is desired to make the substrate glass lighter and easier to handle.

For example, Japanese Patent Application Laid-Open No. 9-249430 discloses that
And SiO_Two 56-65, Al_TwoO_Three Over 15 ~ 23, MgO 0-7, CaO
0-8, MgO + CaO 4-15, Na_TwoO 0-9, K_TwoO 0-1
1, Na _TwoO + K_TwoO 8-12, ZrO_Two Consisting of 0-2, glass
Specific gravity is 2.6 or less, average thermal expansion coefficient is 60 ~ 75 × 10^-7/
Glass composition for substrates with a glass transition point of 660 ℃ or higher
Is disclosed.

[0005] These known examples have a coefficient of thermal expansion that is too low as compared with soda-lime glass, and are not as good as soda-lime glass whose glass specific gravity is 2.55 or less.

The present invention addresses these disadvantages in the prior art,
It was done in view of the problem, the glass strain point is high,
The present invention provides a substrate glass suitable for a PDP having a thermal expansion coefficient equivalent to that of soda-lime glass and a glass specific gravity of 2.55 or less, which is as low as soda-lime glass.

[0007]

According to the present invention, the composition of the glass component is SiO ₂ 61-66, Al ₂ O ₃ 8-14, SiO ₂ + Al
₂ O ₃ 70-77, MgO 1-6, CaO 4-8, SrO 1-5.5,
MgO + CaO + Sr0 9~13, Li 2 O 0~3, Na 2 O 3~
8, K ₂ O 5 to 8, Li ₂ O + Na ₂ O + K ₂ O 9 to 13, SO ₃ 0.03 to
A glass for a display device containing 0.2 in the range of 580 ° C. or more, having a coefficient of thermal expansion of 75 to 85 × 10 ⁻⁷ / ° C. from room temperature to 300 ° C., and a specific gravity of 2.55 or less.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the following components, "%" indicates wt%. In the component system of the present invention, Si
O ₂ is a main component acting as a network former of glass. When the content is less than 61% in the glass, the specific gravity of the glass increases, the strain point of the glass decreases, and the water resistance and chemical resistance deteriorate. On the other hand, if it exceeds 66%, the coefficient of thermal expansion becomes too small, and the high-temperature viscosity of the glass melt increases,
Float molding becomes difficult. Therefore, it is introduced in the range of 61 to 66%.

Al ₂ O ₃ plays a role in the glass network and can form the glass in a stable manner, raises the strain point and viscosity of the glass to improve the heat resistance, and also improves the chemical resistance of the glass,
Improves water resistance. If Al ₂ O ₃ is less than 8% in the glass, the strain point of the glass decreases, while if it exceeds 14%, the high-temperature viscosity of the glass melt increases, the tendency of devitrification increases, and it is difficult to form by the float method. become. Therefore, it is introduced in the range of 8 to 14%.

It is not preferable that the content of SiO ₂ + Al ₂ O ₃ in the glass is less than 70%, and that the content of a divalent component oxide or an alkali metal oxide is excessively increased, because the glass specific gravity increases. If the content of SiO ₂ + Al ₂ O ₃ exceeds 77%, the coefficient of thermal expansion becomes too small, and the high-temperature viscosity of the glass melt becomes high, making the float molding difficult. Therefore, the range is 70 to 77%, preferably 74 to 77%.

MgO lowers the devitrification temperature and raises the strain point of the glass as compared with other divalent component oxides, and is useful for moderate adjustment. Poor action, containing more than 6% lowers the coefficient of thermal expansion of the glass, increases the high temperature viscosity, and inhibits homogeneous melting. Therefore, it is introduced in the range of 1 to 6%.

CaO is SiO ₂ as the main divalent component oxide.
Has a function of lowering the high-temperature viscosity of the melt in glass mainly composed of Al ₂ O ₃ and suppressing the occurrence of devitrification by an appropriate introduction thereof, but the effect is insufficient when the content is less than 4% in the glass. On the other hand, if it exceeds 8%, the tendency of devitrification increases,
The glass specific gravity also increases. Therefore, it is introduced in the range of 4 to 8%.

SrO has the effect of lowering the high-temperature viscosity of the glass melt together with CaO and suppressing the occurrence of devitrification, and is introduced to adjust the thermal expansion coefficient and strain point of the glass. If it is less than 1%, the effect is insufficient, while if it exceeds 5.5%, the specific gravity increases, which is not preferable. Therefore, it is introduced in the range of 1 to 5.5% or less. Note that BaO, which is a similar divalent metal oxide, should not be introduced because it causes an increase in the specific gravity of glass.

Further, within the above composition range, MgO +
By setting the total of CaO + SrO in the range of 9 to 13%, the viscosity-
A glass having an appropriate temperature gradient, good moldability, excellent heat resistance, chemical durability, etc., and a coefficient of thermal expansion in an appropriate range can be obtained. The sum of MgO + CaO + SrO is 13
%, The thermal expansion coefficient of the glass increases and the tendency to devitrify increases, the chemical durability decreases, and the glass specific gravity increases. If it is less than 9%, the high temperature viscosity increases, making melting and molding difficult, and the coefficient of thermal expansion becomes too small. Preferably, the total amount is in the range of 11 to 13%.

[0015] Na ₂ O acts together with K ₂ O as a primary glass-melting agent, and is indispensable for maintaining the coefficient of thermal expansion of the glass at a moderate level. If Na ₂ O is less than 3% in the glass, the coefficient of thermal expansion becomes too small, the glass melting becomes insufficient, and the homogeneity and clarity are impaired. On the other hand, if it exceeds 8%, the strain point of the glass will be too low, and the water resistance and chemical resistance will also deteriorate. Therefore, it is introduced in the range of 3 to 8%.

K ₂ O is a glass melting agent as described above, and appropriately adjusts the coefficient of thermal expansion of the glass and suppresses the movement of alkali ions in the glass by the alkali effect of mixing with Na ₂ O. Increase the volume resistivity of glass. 5% in glass
If it is less than 10%, the effects are insufficient, and if it exceeds 8%, the thermal expansion coefficient becomes excessive and the strain point is too low.

Note that the same alkali metal oxide, Li
_{Since 2} O acts as a strong glass-melting agent, the introduction of a small amount is not denied, but if it exceeds 3%, the strain point of the glass is lowered and the coefficient of thermal expansion is too small.

By setting the total amount of Li ₂ O + Na ₂ O + K ₂ O in the glass to 9 to 13%, the strain point, the thermal expansion coefficient, the high temperature viscosity and the devitrification temperature of the glass can be maintained in appropriate ranges. it can. If the total amount of Li ₂ O + Na ₂ O + K ₂ O is less than 9%,
As the coefficient of thermal expansion becomes too small, the tendency of devitrification increases. If it exceeds 13%, the strain point of the glass is too low, and the volume resistivity is low. Preferably the total amount 11-13
%.

SO ₃ is introduced into the raw material batch in the form of sodium sulfate or barium sulfate as a component for improving the melting and clarity of the glass, and is contained in the glass in the range of 0.03 to 0.2 wt% as SO _3. Introduce as much as possible.
If it is less than 0.03% in the glass, melting and fining effects cannot be obtained,
If it exceeds 0.2%, erosion of the furnace material is accelerated during glass production, and disadvantages such as easy foaming of the glass occur.
Although SO ₃ depends on the amount of the reducing agent (for example, carbon) and the melting atmosphere, about half the amount is scattered with respect to the amount introduced, and the remaining amount remains in the glass. Is good.

In the present invention, chloride,
It is desirable to introduce fluoride, for example CaF ₂ , MgF ₂ ,
By introducing metal fluorides and chlorides such as NaCl and CaCl _{2 to} lower the viscosity and surface tension of the glass melt,
In the case where the clarity is improved and the electric melting method is employed, it is effective in preventing deterioration and deterioration of the electrode. However, the amount of glass in raw material batches as fluorine or chlorine content
(Oxide) It is desirable to add 0.3 wt% or less to 100 wt%. If it exceeds 0.3 wt%, it tends to erode the furnace material and lower the strain point of glass.

Further, as a raw material for improving the melting and clarity of glass, it is preferable to introduce a nitrate. That is, it is introduced into the raw material batch in a raw material form such as barium nitrate, sodium nitrate, and potassium nitrate, and is appropriately added as NO _{3 in} a range of 0.3 wt% or less based on 100 wt% of glass equivalent (oxide) of the raw material batch. It is desirable to introduce.

In the present invention, when the electric melting method by direct energization is employed, it is necessary to avoid forming an alloy by reacting with a commonly used electrode such as molybdenum. As ₂ O ₃ , Sb as fining agent
The use of ₂ O ₃ etc. should be avoided.

In the present invention, by setting the glass specific gravity to 2.55 or less, it is possible to increase the weight and the ease of handling of a display device such as a PDP, which is becoming larger in size. Further, by setting the strain point of the glass (the temperature at which the glass exhibits a viscosity of 10 ^14.5 poises) to 580 ° C. or more, the substrate glass does not become distorted even after various repeated heat treatments exceeding 500 ° C. Furthermore, the coefficient of thermal expansion (room temperature to 300 ° C) is 75
With the same level of soda-lime glass as ~ 85 × 10 ^-7 / ° C, conductive wires to be patterned on the glass substrate and low-melting glass for further insulating coating use the same materials as before. be able to.

[0024]

Examples: Silica sand, aluminum hydroxide, magnesium oxide, calcium carbonate, barium carbonate, strontium carbonate, zircon sand, lithium carbonate, sodium carbonate, potassium carbonate, sodium sulfate (sodium and SO ₃
The mixture was filled in a platinum refractory crucible and heated and melted at 1500 ° C for about 4 hours in an electric furnace. Next, the molten glass was poured into a mold, and a glass block having a size of about 200 mm □ × 35 mm and a glass plate having a size of about 200 mm □ × 4 mm were transferred into an electric furnace maintained at 600 to 650 ° C. It was gradually cooled in the furnace.

Tables 1 and 2 show the glass (oxide) composition. For these glass samples, the average thermal expansion coefficient (X10 ^-7 / ° C) from room temperature to 300 ° C, the strain point (
10 ^14.5 poise), the transition point (temperature-expansion gradient change <transition point> when measuring the thermal expansion coefficient), and the glass specific gravity at room temperature. Table 1 shows the results.
(Example) and Table 2 (Example, Comparative Example) are shown.

[Table 1 Example] Example(wt%) 1 2 3 4 5 6 7 8 SiO_Two 61.9 61.9 62.9 61.9 63.8 63.9 63.9 64.9 Al_TwoO_Three 13.0 12.0 12.0 13.0 11.0 13.0 11.0 10.0 Subtotal 74.9 73.9 74.9 74.9 74.8 76.9 74.9 74.9 Li_TwoO--------Na_TwoO 5.0 7.5 5.0 7.5 7.0 6.5 6.0 6.0 K_TwoO 7.0 5.5 8.0 5.5 5.5 5.5 7.0 6.0 Subtotal 12.0 13.0 13.0 13.0 12.5 12.0 13.0 12.0 MgO 3.0 4.0 3.0 3.0 3.5 4.0 1.0 5.0 CaO 7.0 5.0 5.0 5.0 5.0 4.0 7.5 6.0 SrO 3.0 4.0 4.0 4.0 4.0 3.0 3.5 2.0 Subtotal 13.0 13.0 12.0 12.0 12.5 11.0 12.0 13.0 SO ₃ 0.08 0.08 0.1 0.1 0.15 0.05 0.05 0.1 Thermal expansion coefficient (X10^-7/ ・ C) 80 82 81 82 81 80 83 80 Strain point (° C) 614 586 601 590 586 595 592 593 593 Transition point (° C) 643 622 632 625 621 634 634 620 627 Specific gravity 2.55 2.55 2.55 2.54 2.54 2.52 2.55 2.52

[Table 2 Examples and Comparative Examples] Examples Comparative Examples(wt%) 9 10 11 1 2 3 4 5 SiO_Two 65.9 64.4 65.9 61.9 62.7 66.7 63.0 62.0 Al_TwoO_Three 9.0 11.0 11.0 11.0 14.0 7.0 8.0 8.0 Subtotal 74.9 75.4 76.9 72.9 76.7 73.7 71.0 70.0 Li_TwoO-1.0------Na_TwoO 6.0 3.0 6.0 4.0 8.0 7.0 5.0 9.0 K_TwoO 6.0 7.5 6.0 6.0 3.0 6.0 6.0 9.0 Subtotal 12.0 11.5 12.0 10.0 11.0 13.0 11.0 18.0 MgO 5.0 2.0 4.5 2.0 3.0 4.0 6.0 3.0 CaO 6.0 7.0 5.5 8.0 5.0 5.0 8.0 5.0 SrO 2.0 4.0 1.0 7.0 4.0 4.0 4.0 4.0 Subtotal 13.0 13.0 11.0 17.0 12.0 13.0 18.0 12.0  SO ₃ 0.1 0.1 0.1 0.1 0.3 0.3 0.01 0.01 Thermal expansion coefficient (X10^-780 81 77 78 71 82 78 96 Strain point (° C) 588 590 597 620 601 563 598 531 Transition point (° C) 622 622 633 642 637 600 627 569 Specific gravity 2.52 2.55 2.49 2.62 2.53 2.54 2.58 2.55

Examples 1 to 11 in Tables 1 and 2 are glasses according to the present invention, and the glass preferably has a strain point of 580 ° C. or more and a glass specific gravity of 2.55 or less. Further, the thermal expansion coefficient is close to that of soda-lime glass, and is moderate, such as 75 to 85 × 10 ⁻⁷ / ° C.

Although the transition point is not specified, the temperature of the soda-lime glass is about 560 ° C., whereas the temperature of the glass of the example is significantly higher than 600 ° C., indicating that the glass has excellent heat resistance. .

Further, although not shown, the volume resistivity (at 250
° C) is 10 ⁹ Ω · cm or more, which is excellent in electrical insulation and is suitable as a substrate glass for a display device, particularly a substrate glass for a PDP.

[0031]

The glass of the present invention has a glass specific gravity, a coefficient of thermal expansion of glass similar to that of soda-lime glass, and a high strain point.
Suitable for use as a substrate glass for, further suitable for melting by the direct current method and molding by the float method, it is possible to continuously produce a homogeneous glass at low cost,
It has the effect of being suitable for mass production.

Claims (1)

[Claims] 1. A glass component composition, in wt%, SiO ₂ from 61 to 6
6, Al ₂ O ₃ 8 to 14, SiO ₂ + Al ₂ O ₃ 70 to 77, MgO 1 to 6, C
aO 4-8, SrO 1-5.5, MgO + CaO + Sr0 9-13, L
_{i 2 O0~3, Na 2 O 3~8} , K 2 O 5~8, Li 2 O + Na 2 O + K
₂ O 9-13, SO ₃ 0.03-0.2 contained, the glass has a strain point of 580 ° C or higher, and a coefficient of thermal expansion between room temperature and 300 ° C of 75.
A substrate glass for a display device, wherein the substrate glass has a specific gravity of up to 85 × 10 ⁻⁷ / ° C. and a specific gravity of 2.55 or less.