JPH11100226A - Substrate glass for display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain substrate glass for display device suitable for fusion including direct energizing fusion and float method molding, having an adequate thermal property, relatively low specific gravity and particularly suitable for PDP. SOLUTION: This substrate glass contains, by wt.%, SiO2 of 60-65, Al2 O3 of 9-14, B2 O3 of 0-5, SiO2 +Al2 O3 +B2 O3 of 70-76, MgO of 0-5, CaO of 4-10, SrO of 0-5, BaO of 1-8, MgO+CaO+SrO+BaO of 10-16, Li2 O of 0-3, Na2 O of 6-10, K2 O of 1-5, Li2 O+Na2 O+K2 O of 9-14 and ZrO2 of 1.0-3.5 and has a glass specific gravity of <=2.6. And the strain point of the glass is preferably >=500 deg.C and the coefficient of thermal expansion at 300 deg.C is preferably 80-10<-7> / deg.C.

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) is a glass suitable as a substrate glass,
Melting including electric melting method and molding by float method
The present invention relates to a substrate glass for a display device which is easy to make (plate making).

[0002]

2. Description of the Related Art Conventionally, soda-lime-silica glass is often used as a substrate glass for display devices. As an example, in the case of a glass substrate for PDP, an electrode such as nickel or aluminum, an insulating coating film or the like is applied to the glass substrate by screen printing or the like, and firing at a temperature exceeding 500 ° C. is repeated to produce a panel. If the substrate glass has a different coefficient of thermal expansion from the electrodes and the coating film, cracks and peeling are liable to occur.Therefore, it is necessary to match the coefficients of thermal expansion.In the soda-lime-silica glass, the coefficient of thermal expansion is 90 × 10 ^-7 / ° C is useful in that it has a coefficient of thermal expansion close to that of electrodes and coatings, but the strain point is 510 ° C.
Since the temperature is in the vicinity, there is a problem that thermal deformation is apt to occur during repeated firing, and the production yield is remarkably deteriorated.

JP-A-3-40933 discloses a SiO ₂ component, Al ₂ O
_Three components, divalent component oxides including CaO component, Na ₂ O
A glass composition for substrates consisting of alkali metal oxides such as the components, ZrO ₂ components, etc., which hardly deforms even when heat-treated at around 600 ° C, and whose coefficient of thermal expansion is almost the same as that of soda-lime-silica glass. Is disclosed. Generally, in this component system, the bivalent component oxide is excessive, increasing the specific gravity of the glass, increasing the high-temperature viscosity of the glass melt, deteriorating homogenization and clarity, and also complicating moldability. There is a fear that. In order to improve homogenization and clarity,
It is necessary to add SO ₃ , Sb ₂ O ₃ , or As ₂ O ₃ in excess as a fining agent.For example, in the case of direct energization melting, they react with the electrode to deteriorate or deteriorate the electrode,
There is concern that the glass may be colored.

JP-A-8-133778 discloses that a glass composition containing a SiO ₂ component, a divalent component oxide, an alkali metal oxide and the like but not a ZrO ₂ component is used as a PDP substrate. ing. However, the ZrO ₂ component can maintain the strain point of the glass at a desired high temperature in the presence of a small amount, can suppress the occurrence of devitrification, and should be indispensable for providing the glass with water resistance and chemical resistance. is there.

Japanese Patent Application Laid-Open No. 7-257937 discloses an SiO ₂ component, Al ₂ O
₃ components, oxides of divalent components including CaO component, K ₂
Consists of alkali metal oxides such as O component, ZrO ₂ component, etc.
A glass composition applied to a DP substrate is disclosed.
However, there is a concern that the SiO ₂ component as a network former is low, glass formation is correspondingly unstable, devitrification tends to occur, and specific gravity tends to increase.

The present invention has been accomplished after various studies in view of the problems in the prior art, and has been completed. The present invention is suitable for melting including direct energization melting and float molding, and has appropriate thermal characteristics. A glass with relatively low specific gravity, especially PD
A substrate glass for a display device suitable for P is provided.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a method for preparing SiO.sub._Two
 61-65, Al_TwoO_Three 9-14, B_TwoO_Three 0-5, SiO_Two+ Al_TwoO _Three 
+ B_TwoO_Three 70-76, MgO 0-5, CaO 4-10, SrO 0
5, BaO 1-8, MgO + CaO + SrO + BaO 10-16, Li_TwoO
 0-3, Na_TwoO 6-10, K_TwoO 1-5, Li_TwoO + Na_TwoO + K_TwoO
9-14, and ZrO_Two Contained in the range of 1.0 to 3.5, glass
Substrate glass for display devices with a specific gravity of 2.6 or less
It is. In the above, the strain point of the glass
The coefficient of thermal expansion from temperature to 300 ° C is 80 × 10^-7/ ℃ or more
Preferably.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the component system of the present invention, SiO ₂ is a main component acting as a network former of glass, and if it is less than 61% by weight, it is difficult to form glass stably and devitrification occurs. It tends to lower the strain point of the glass, degrade water resistance and chemical resistance, and increase the specific gravity of the glass. On the other hand, if it exceeds 65%, the high-temperature viscosity of the glass melt becomes high, and it becomes difficult to form by a float method. Therefore
The range is 61 to 65%.

If the Al ₂ O ₃ content is less than 9%, 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, the range is 9 to 14%.

Although B ₂ O ₃ is not an essential component, it is appropriately introduced to lower the high-temperature viscosity and facilitate glass melting. However, the strain point and the coefficient of thermal expansion tend to decrease, and should not be introduced in excess of 5%.

It is not preferable that the content of SiO ₂ + Al ₂ O ₃ + B ₂ O ₃ is less than 69% and that the content of the divalent component oxide or alkali metal oxide is excessively increased, because the glass specific gravity increases. If the content of SiO ₂ + Al ₂ O ₃ + B ₂ O ₃ exceeds 76%, the coefficient of thermal expansion is reduced, and the high-temperature viscosity of the glass melt is increased, making the float molding difficult.

ZrO ₂ improves the water resistance and chemical resistance of glass. It also has the effect of raising the strain point of the glass and suppressing the occurrence of devitrification.
If it exceeds 3.5%, on the contrary, the tendency of devitrification increases, making it difficult to melt the glass and form it by the float method.

MgO lowers the devitrification temperature by introducing a small amount,
It is also useful in raising and adjusting the strain point of glass as compared with other divalent component oxides, and is appropriately introduced. However, when the content exceeds 5%, the coefficient of thermal expansion of the glass decreases. , The tendency to devitrification increases. Therefore, it is introduced in a range of 5% or less.

CaO has the effect of lowering the high-temperature viscosity of the glass melt in the presence of BaO, but if it is less than 4%, its effect is insufficient, while if it exceeds 10%, the tendency to devitrify becomes large. Increase specific gravity. Therefore, the range is 4 to 10%.

As described above, BaO has the effect of lowering the high-temperature viscosity of the glass melt and suppressing the occurrence of devitrification in the presence of CaO, but if it is less than 1%, the effect of suppressing devitrification is insufficient. On the other hand, if it exceeds 8%, the strain point of the glass becomes too low, and the specific gravity of the glass increases. Therefore, it is in the range of 1 to 8%.

SrO is appropriately introduced to adjust the viscosity of the molten glass, the coefficient of thermal expansion of the glass, and the strain point. However, if it exceeds 5%, the specific gravity increases, which is not preferable.

Furthermore, by keeping the total of the divalent component oxides (CaO, MgO, BaO, SrO) in the above composition range in the range of 10 to 16%, the melting property of the glass is maintained in a good range. In addition, it is possible to obtain a glass having an appropriate viscosity-temperature gradient, good moldability, excellent heat resistance, chemical durability and the like, and a thermal expansion coefficient in an appropriate range. If the total amount of the divalent component oxides exceeds 16%, the thermal expansion coefficient of the glass is particularly increased, and the tendency of devitrification is increased, whereby the chemical durability is reduced and the specific gravity of the glass is increased. If it is less than 10%, the high temperature viscosity increases to make melting and molding difficult, and the coefficient of thermal expansion decreases.

Although Li ₂ O acts as a strong glass melting agent, it lowers the coefficient of thermal expansion of the glass and also lowers the strain point. Therefore, Li ₂ O is appropriately introduced within a range of 3% or less.

Na ₂ O works together with K ₂ O as a glass melting agent, and is indispensable for maintaining the thermal expansion coefficient of the glass at an appropriate level. If the content of Na ₂ O is less than 6%, the melting of the glass becomes insufficient, and the homogeneity and clarity are impaired. The other 10
%, The strain point of the glass becomes too low, and the water resistance and chemical resistance also deteriorate. Therefore, it is introduced in the range of 6 to 10%.

K ₂ O suppresses migration of alkali ions in the glass due to the above-mentioned reason and the mixed alkali effect with Na ₂ O, and increases the volume resistivity of the glass. If it is less than 1%, their effects are insufficient, and if it exceeds 5%, the coefficient of thermal expansion becomes too large and the strain point is too low. Further, in order to lower the glass specific gravity, it is preferable to set the range of 1 to 4%.

The alkali metal oxides (Li ₂ O, Na ₂ O, K ₂
By setting the total amount of O 2) to 9 to 14%, the strain point, the coefficient of thermal expansion, the high temperature viscosity and the devitrification temperature of the glass can be kept in appropriate ranges. If the total amount of the alkali metal oxides is less than 9%, the coefficient of thermal expansion decreases, and the tendency to devitrify increases. If it exceeds 14%, the strain point of the glass will be too low, and the specific gravity will increase, and the volume resistivity will decrease. Accordingly, the range is set to 9 to 14%, but the range is preferably set to 12 to 14% in consideration of easy melting property of glass.

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,
It is effective to improve the clarity and to prevent the electrode from being deteriorated and deteriorated when the electro-melting method is used. However, the amount of fluorine or chlorine is 100% by weight of the raw material batch in terms of glass (oxide) in terms of glass. It is important to add 0.5 wt% or less extrapolated, and if it exceeds 0.5 wt%, the erosion of the furnace material tends to be severe and the strain point of the glass is lowered.

Further, nitrate is preferably introduced as a raw material for improving the melting and refining properties of the glass. That is, for example, barium nitrate, sodium nitrate, and potassium nitrate are introduced into a raw material batch in the form of raw materials, but most of nitrates generate oxygen during the initial melting of the glass, and trace amounts of S, Fe, and Ti in the glass. In order to maintain the reduced components in an oxidized state, the adverse effects such that these reduced components react with an electrode of molybdenum or the like to wear the electrodes are suppressed.

The nitrate is preferably extrapolated as NO _{3 in an} amount of 4% by weight or less, more preferably in the range of 1 to 4% by weight, based on 100% by weight (oxide) in terms of glass of the raw material batch. If it exceeds 4% by weight, the dissolution rate of the raw material batch becomes excessive, and it is difficult to obtain a stable molten state. The above-mentioned chloride, fluoride or nitrate is appropriately introduced as needed, and both may be used together.

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 2} O ₃ and S content, sulfates (partially remaining as SO _{3 in the} glass) should be kept in small amounts (0.3% or less). It is better to avoid the incorporation of a reactive ZnO raw material.

Further, in order to facilitate mass production by float molding, and to prevent volatilization under a reducing atmosphere such as nitrogen and hydrogen during molding and to prevent coloring of the glass, PbO is used.
Volatile components such as ZnO and ZnO should be avoided.

In the present invention, by setting the glass specific gravity to 2.6 or less, preferably 2.58 or less, the display device such as a PDP, which is becoming larger in size, is reduced in weight and ease of handling, and the strain point of the glass is raised to 580 ° C. With the above, 50
The substrate glass is not distorted by various heat treatments exceeding 0 ° C and has a coefficient of thermal expansion (from room temperature to 300 ° C).
(° C) is set to 80 × 10 ^-7 / ° C or higher, so that the difference in the coefficient of thermal expansion from a thick film or the like is reduced or eliminated, and a glass with good adhesion to them is obtained. It is suitable.

[0028]

[Example] Platinum was used as a raw material composed of silica sand, aluminum hydroxide, boric anhydride, magnesium carbonate, calcium carbonate, barium carbonate, strontium carbonate, zircon sand, lithium carbonate, sodium carbonate, potassium carbonate, calcium fluoride, and barium nitrate. The mixture was filled in a refractory crucible and melted by heating at 1500 ° C for about 4 hours in an electric furnace. Next, the molten glass was poured into a mold to form a glass block having a size of about 200 mm □ × 35 mm, transferred to an electric furnace maintained at 630 ° C., and gradually cooled in the furnace.

Tables 1 and 2 show the glass (oxide) composition based on the raw material preparation. In each case, Ca
F content to be introduced in the form of F _2, F 0.2 as Ba (NO ₃₎ extrapolation added and introduction amount to the glass oxide composition total 100 wt% for NO ₃ minutes to be introduced in the _second form (wt%) %, NO ₃
Common with 0.3%.

For these glass samples, room temperature to 300
Average coefficient of thermal expansion in ° C (X10 ^-7 / ° C), strain point (temperature at which glass exhibits a viscosity of 10 ^14.5 poise), transition point (change in temperature-expansion gradient when measuring thermal expansion coefficient <transition> point) , molding temperature (temperature glass exhibits a viscosity of 10 ⁴ poises), and it was measured glass gravity. Table 1 (Example) shows the results.
The results are shown in Table 2 (Examples and Comparative Examples).

[Table 1 Example] Example (wt%) 1 2 3 4 5 6 7 8 SiO ₂ 61.0 62.0 61.4 63.3 63.0 61.2 61.5 61.3 Al ₂ O ₃ 12.5 13.0 10.1 10.3 10.5 11.2 9.5 9.7 B ₂ O ₃ 0 0 0 0 0 0 0 1.3 Subtotal 73.5 75 71.5 73.6 73.5 72.4 71.0 72.3 Li ₂ O 0 0 0 0 0 0 0 0 Na ₂ O 8.2 8.0 7.2 8.8 7.2 8.1 8.0 7.6 K ₂ O 4.6 4.0 3.8 2.7 4.3 4.4 4.5 4.5 Subtotal 12.8 12 11 11.5 11.5 12.5 12.5 12.3 MgO 2.5 2.0 1.5 0 1 2.2 2.0 2.2 CaO 6.8 7.0 7.0 8.0 6.6 7.6 7.5 8.0 SrO 0 0 0 0 0 0 0 0 BaO 2.0 2.0 6.0 5.4 6.0 4.3 4.5 3.0 Subtotal 11.3 11 14.5 13.4 13.6 14.1 14.0 13.2 ZrO ₂ 2.4 2 3.0 1.5 1.4 1.0 2.5 2.2 Thermal expansion coefficient 84 81 80 80 81 84 83 81 Strain point 592 602 591 596 601 595 598 591 Transition point 627 632 635 627 632 628 623 625 625 Molding temperature 1172 1196 1196 1159 1161 1148 1135 1137 Specific gravity 2.57 2.55 2.58 2.58 2.57 2.57 2.59 2.59

[0032] Table 2 - Examples and Comparative Examples] implementation example comparisons Example (wt%) 9 10 11 12 1 2 3 4 SiO 2 62.8 62.2 63.5 62.1 65.0 61.5 54.0 57.7 Al 2 O 3 9.7 9.6 10.5 9.6 12.0 16.8 9.0 6.5 B ₂ O ₃ 0 0 0 0 0 0 0 0 Subtotal 72.5 71.8 74.0 71.7 77 78.3 63 64.2 Li ₂ O 1.0 0.6 0 0 0 0 0 0 Na ₂ O 8.2 8.2 8.7 8.1 7.0 12.4 4.0 4.5 K ₂ O 1.6 3.0 4.8 4.5 2.0 3.5 9.0 6.6 Subtotal 10.8 11.8 13.5 12.6 9.0 15.9 13 11.1 MgO 2.0 2.0 1.7 2.0 4.0 3.4 3.0 1.8 CaO 7.7 7.5 6.1 7.6 8.0 0.4 7.7 5.1 SrO 0 0 2.0 1.6 0 0 0 7.0 BaO 4.5 4.5 1.5 2.1 0 2.0 9.6 7.8 Subtotal 14.2 14.0 11.3 13.3 12 5.8 20.3 21.7 ZrO ₂ 2.5 2.4 1.2 2.5 2.0 0 3.7 3.0 Thermal expansion coefficient 80 81 84 83 72 88 85 81 Strain point 600 593 588 585 631 576 603 581 Transition point 632 628 621 626 670 616 637 627 627 Molding temperature 1155 1150 1160 1140 1225 1260 1129 1135 Specific gravity 2.58 2.58 2.57 2.58 2.52 2.46 2.74 2.77

In Tables 1 and 2, Examples No. 1 to No. 12 are glasses according to the present invention, which have good melting and fining properties in the manufacturing process, and have a strain point of 580 ° C. or higher and have heat resistance. Good. The coefficient of thermal expansion is 80 × 10 ⁻⁷ / ° C. or more, which is close to the coefficient of thermal expansion with electrodes and thick films. Further, by setting the glass specific gravity to 2.6 or less, it is possible to reduce the weight of a display device such as a PDP, which is increasing in size, and to enhance the ease of handling.
Further, although not displayed, the volume resistivity 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.

[0034]

The glass of the present invention has a coefficient of thermal expansion of glass,
In terms of strain point, glass specific gravity, etc., it is suitable as a substrate glass for a display device, particularly a substrate glass for a PDP, and has a good melting property of glass, and is suitable for melting property by a direct current method and moldability by a float method, A homogeneous glass can be produced continuously at a low cost, which is advantageous for mass production.

Claims (2)

[Claims] (1) SiO ₂ 61-65, Al ₂ O ₃ 9-14, B ₂
O ₃ 0-5, SiO ₂ + Al ₂ O ₃ + B ₂ O ₃ 70-76, MgO 0-5, C
aO 4-10, SrO 0-5, BaO 1-8, MgO + CaO + Sr0
+ BaO 10-16, Li ₂ O 0-3, Na ₂ O 6-10, K ₂ O 1
_{5, Li 2 O + Na 2} O + K 2 O9~14, and contain a range of ZrO ₂ 1.0 to 3.5, the display device substrate glass, wherein the glass specific gravity of 2.6 or less. 2. The glass has a strain point of 580 ° C. or higher and a room temperature of 300 ° C. or more.
2. The substrate glass for a display device according to claim 1, wherein the coefficient of thermal expansion at 80 ° C. is 80 × 10 ⁻⁷ / ° C. or more.