JPH11180727A - Substrate glass composition for display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce the substrate glass for the display device suitable to a melting and floating forming method including a directly energizing melting, having a moderate heat performance, being a low density glass and particularly suitable for PDP. SOLUTION: The glass is incorporated with 61-65 SiO2 , 9-13 Al2 O3 , 0.5-3.5 ZrO2 , 71-78 SiO2 +Al2 O3 +ZrO2 , 1-6 MgO, 3-9 CaO, 1-5 SrO, 0-5 BaO, 10-15 MgO+ CaO+SrO+BaO, 0-3 Li2 O, 7-10 Na2 O, 1-5 K2 O, 9-14 Li2 O+Na2 O+K2 O by wt.%, and the glass has a specific density of <=2.60 and a distortion point of >=570 deg.C, 10<4> poise temp. of <=1200 deg.C, a temp. difference of poise temp.-devitrification temp. of >=10 deg.C and a coefficient of thermal expansion from room temp. to 300 deg.C of >=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).
The present invention relates to a glass composition 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]

2. Description of the Related Art Conventionally, a display device
As the sheet glass, soda-lime-silica glass is used.
There are many cases. As an example, PDP glass substrates
In addition, electrodes such as nickel and aluminum
And insulation coating by screen printing etc., 500 ℃
The panel is manufactured by repeating firing at a temperature exceeding. Base
If the sheet glass has a different coefficient of thermal expansion from the electrode or coating,
Cracks and delamination are likely to occur, so it is necessary to match the coefficient of thermal expansion
There is a thermal expansion in the soda-lime-silica glass.
90 × 10 ^-7/ ° C near the coefficient of thermal expansion with electrodes and coatings
Useful at close points, but with strain points around 510 ° C
Therefore, thermal deformation easily occurs during repeated firing,
There is a problem that the yield is remarkably deteriorated.

[0003] JP-A-3-40933 discloses a SiO ₂ component,
A glass composition for substrates consisting of Al ₂ O ₃ components, divalent metal oxides such as CaO, alkali metal oxides such as Na ₂ O, ZrO ₂ components, etc., which are almost deformed even at a heat treatment at around 600 ° C. A glass having a coefficient of thermal expansion almost equal to that of soda-lime-silica glass is disclosed. In general, this component system contains an excess of divalent metal oxides, which increases the specific gravity of the glass, increases the high-temperature viscosity of the glass melt, deteriorates homogeneity and clarity, and makes molding difficult. There is a fear that.
In order to improve homogenization and clarity, it is necessary to add an excessive amount of SO ₃ , Sb ₂ O ₃ , or As ₂ O ₃ as a melting accelerating / fining agent. However, there is a fear that the electrode reacts with the electrode to cause deterioration and deterioration of the electrode or to give coloring to the glass.

Japanese Patent Application Laid-Open No. 7-257937 discloses an SiO ₂ component,
A glass composition comprising an Al ₂ O ₃ component, a divalent metal oxide such as CaO, an alkali metal oxide such as K ₂ O, a ZrO ₂ component, and the like, and applied to a PDP substrate is disclosed. However, since the SiO ₂ component as a network former is low, glass formation is correspondingly unstable, and devitrification tends to occur. Further, there is a concern that the specific gravity of the glass is easily increased, and particularly in the case of a large-sized display device, the weight of the device is increased, making it difficult to handle.

[0005] Japanese Patent Publication No. 9-507207 discloses a network.
SiO, the performer_TwoIngredients and Al _TwoO_Three Ingredient, B_TwoO_ThreeSuccess
Min, ZrO_TwoComponent, divalent metal oxide, and alkali metal
Contains oxides, has a higher strain point than soda-lime glass,
The expansion coefficient is as high as soda-lime glass.
A glass composition suitable as fire glass is disclosed.
However, SiO_TwoLow ratio of components, etc., relatively divalent metal acid
Oxides, alkali metal oxides, etc.
Unstable in composition, easy to devitrify, and increased glass specific gravity
I do.

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 electric current melting and float molding, and has appropriate thermal characteristics. A glass with relatively low specific gravity, especially PD
A substrate glass composition 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 9-13, ZrO_Two 0.5-3.5, SiO_Two+ Al _TwoO
_Three + ZrO_Two 71-78, MgO 1-6, CaO 3-9, SrO 1
5, BaO 0-5, MgO + CaO + Sr0 + BaO 10-15, Li_TwoO
 0-3, Na_TwoO 7-10, K_TwoO 1-5, Li_TwoO + Na_TwoO + K_TwoO
 9-14, glass specific gravity 2.60 or less, glass
The strain point of the glass is 570 ° C or higher,^Four Poise temperature (gala
Viscosity is 10^Four At the temperature that becomes poise, molding work
Is less than 1200 ° C and 10^Four Poise temperature-
Devitrification temperature difference of 10 ° C or more and from room temperature of glass 3
The coefficient of thermal expansion at 00 ° C is 80 × 10^-7Display devices that are at least / ° C
It is a mounting substrate glass composition. Display device substrate
It is a lath composition.

[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. If it is less than 61% in the glass, it is difficult to form the glass stably, it is easy to cause devitrification, and the strain point of the glass is lowered, It tends to deteriorate chemical resistance and increase glass specific gravity. 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
Introduce in the range of 61-65%.

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 the Al ₂ O ₃ content is less than 9% in the glass, the strain point of the glass decreases, while if it exceeds 13%, the high-temperature viscosity of the glass melt increases, the tendency to devitrify increases, and the float method molding becomes difficult. Become. Therefore, it is introduced in the range of 9 to 13%.

ZrO ₂ improves the water resistance and chemical resistance of glass. Also, it 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 and float-mold the glass and increasing the specific gravity of the glass. Therefore, it is introduced in the range of 0.5 to 3.5%.

It is to be noted that SiO ₂ + Al ₂ O ₃ + ZrO ₂ in glass is 71%
It is not preferable that the content is less than the above value and the excess of the divalent component oxide or alkali metal oxide increases the glass specific gravity. Further, when the content of SiO ₂ + Al ₂ O ₃ + ZrO ₂ exceeds 78%, the coefficient of thermal expansion is reduced and the high-temperature viscosity of the glass melt is increased, making the float molding difficult. Therefore 71
7878 wt%, preferably 74-77%.

In this component system, it is a network former similar to SiO ₂ , and B ₂ O ₃ for stably forming glass can be appropriately introduced. B ₂ O ₃ lowers the high temperature viscosity and facilitates glass melting. However, the strain point and the coefficient of thermal expansion tend to decrease, and the amount to be introduced should be 2% or less.

[0013] 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. The effect is poor, and if the content exceeds 6%, the coefficient of thermal expansion of the glass is reduced, and the tendency of devitrification is increased. Therefore 1
Introduce in the range of 6%.

CaO is SiO ₂ as a main divalent component oxide.
, Al ₂ O _3, or the lower the high temperature viscosity of the melt in the glass mainly comprising, also has the effect of suppressing the occurrence of devitrification due to its moderate introduced, is insufficient its effect in the glass less than 3% On the other hand, if it exceeds 9%, the tendency of devitrification increases,
It also increases the glass specific gravity. Therefore, it is introduced in the range of 3 to 9%.

SrO, together with CaO, has the effect of lowering the high-temperature viscosity of the glass melt and suppressing the occurrence of devitrification, and is useful in adjusting the coefficient of thermal expansion and strain point of glass. If it is less than 5%, its effect is insufficient, and if it exceeds 5%, the specific gravity increases, which is not preferable. Therefore, it is introduced in the range of 1 to 5%.

BaO, together with CaO and the like, has the effect of lowering the high-temperature viscosity of the glass melt and suppressing the occurrence of devitrification, so that it can be appropriately introduced. However, if it exceeds 5% in the glass, the strain point of the glass decreases. Too much, increasing the specific gravity of the glass. Therefore, it is introduced as needed in the range of 5% or less.

Further, by keeping the total of the divalent metal oxides (CaO, MgO, BaO, SrO) in the above composition range in the range of 10 to 15%, 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. When the total amount of the divalent metal oxides exceeds 15%, the coefficient of thermal expansion of the glass increases, the tendency of devitrification increases, the chemical durability decreases, and the specific gravity of the glass increases. 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 tends to lower the coefficient of thermal expansion of the glass and also lower the strain point. Therefore, Li ₂ O is appropriately introduced in a range of 3% or less in the glass. is there.

Na ₂ O, together with K ₂ O, acts as a main glass melting agent, and is indispensable for maintaining the coefficient of thermal expansion of the glass at an appropriate level. If Na ₂ O is less than 7% in the glass, glass melting becomes insufficient, and homogeneity and clarity are also impaired. On the other hand, if it exceeds 10%, the strain point of the glass becomes too low,
Water resistance and chemical resistance also deteriorate. Therefore, it is introduced in the range of 7 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 2%, their effects are insufficient, and if it exceeds 5%, the coefficient of thermal expansion becomes excessive and the strain point is too low. In order to further reduce the glass specific gravity, it is preferable to set the range of 2 to 4%.

The alkali metal oxides (Li ₂ O, Na ₂ O, K ₂
By setting the total amount of O 2) in the glass 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 2.60 or less, it is possible to increase the weight and ease of handling of a display device such as a PDP, which is becoming larger in size. In addition, by setting the glass strain point (the temperature at which the glass exhibits a viscosity of 10 ^14.5 poise) to 570 ° C or higher, the substrate glass does not become distorted even after various heat treatments exceeding 500 ° C, and the thermal expansion is further improved. Rate (room temperature to 300 ° C)
Since it can be adjusted to 10 ^-7 / ° C or more and up to around 90 × 10 ^-7 / ° C, a thick film or the like (the coefficient of thermal expansion depends on the composition, but is approximately 80 to 90 × 10 ^-7 / ° C) A glass having a small or no difference in the coefficient of thermal expansion from the above and having good adhesion to them is obtained. In addition, the temperature at which the glass viscosity becomes 10 ⁴ poise, which is the reference for molding work, can be set to 1200 ° C. or less, and the devitrification temperature is 10 ° C. lower than 10 ⁴ poise temperature.
The above lowering facilitates the molding operation.

[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
Regarding the F component introduced in the form of F _{2 and} the NO ₃ component introduced in the form of Ba (NO ₃ ) ₂ , the amount of extrapolated addition / introduction (wt%) relative to 100 wt% of the total glass oxide component is F 0.2 %, 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) , (the temperature at which the glass exhibits a viscosity of 10 ² poises) melt temperature, mold temperature
(Temperature glass exhibits a viscosity of 10 ⁴ poise = 10 ⁴ poise temperature), (upper limit temperature devitrification occurs maintained 2 hours glass at a constant temperature) the devitrification temperature, the working temperature range (the molding temperature -
Devitrification temperature), and glass specific gravity. The results are shown in Table 1 (Example) and Table 2 (Example, Comparative Example).

[Table 1 Example] Example (wt%) 1 2 3 4 5 6 7 SiO ₂ * 62.1 62.5 62.6 62.8 61.3 60.8 60.6 Al ₂ O ₃ * 9.6 9.6 9.7 9.7 11.9 11.9 11.8 ZrO ₂ * 2.5 2.5 2.5 2.5 2.5 2.3 2.5 B ₂ O ₃ 0 0 0 0 0 0 0 * Subtotal 74.2 74.6 74.8 75.0 75.7 75.0 74.9 Li ₂ O 0 0 0 0 0.5 0.5 0 Na ₂ O 8.1 8.2 8.2 8.2 8.2 8.2 8.1 K ₂ O 4.5 4.5 4.5 4.6 3.0 2.9 4.5 Subtotal 12.6 12.7 12.7 12.8 11.7 11.6 12.6 MgO 2.0 2.0 2.5 3.1 2.0 2.5 3.0 CaO 7.6 7.7 7.0 6.1 7.7 7.7 6.6 SrO 1.6 3.1 3.1 3.1 3.1 3.2 3.0 BaO 2.1 0 0 0 0 0 0 0 Subtotal 13.3 12.7 12.5 12.3 12.7 13.4 12.6 thermal expansion coefficient (X10 ^{over 7 / · c) 83 85 82} 82 82 83 83 strain point 581 580 573 575 573 574 593 transition 620 620 610 612 605 610 632 melt temperature 1554 1576 1576 1594 1596 1599 1594 molding Temperature 1138 1142 1146 1156 1160 1173 1152 Devitrification temperature 1120 1129 1108 1100 1110 1109 1120 Working temperature range 18 13 38 56 50 64 32 Specific gravity 2.59 2.58 2.59 2.59 2.59 2.59 2.59 (Note: Lower numerical values in each component, subtotal wt% display) Is rounded

[Table 2-Examples and Comparative Examples]Example Comparative example (wt%) 8 9 1 2 3 4 5 SiO_Two* 61.3 63.4 67.1 65.0 61.5 54.0 57.7 Al_TwoO_Three* 10.0 9.8 6.1 12.0 9.5 9.0 6.5 ZrO_Two* 2.5 2.5 1.3 2.0 2.5 3.7 3.0 B ₂ O ₃ 1.3 0 0 0 0 0 0 * Subtotal 73.8 75.7 74.5 79.0 73.5 66.7 67.2 Li_TwoO 0 0 0 0 0 0 0 Na_TwoO 7.6 8.3 7.3 7.0 8.0 4.0 4.5 K ₂ O 4.7 4.6 2.7 2.0 4.5 9.0 6.6 Subtotal 12.3 12.9 10.0 9.0 12.5 13.0 11.1 MgO 2.0 5.4 3.6 4.0 2.0 3.0 1.8 CaO 7.5 3.0 9.8 8.0 7.5 7.7 5.1 SrO 3.1 3.1 0 0 0 0 7.0 BaO 0 0 2.1 0 4.5 9.6 8.0 Subtotal 12.6 11.5 15.5 12.0 14.0 20.3 21.9 Thermal expansion coefficient (X10^-7/ ・ C) 82 82 77 72 83 85 81 Strain point 575 589 592 631 598 603 581 Transition point 622 630 634 670 623 637 627 Melting temperature 1575 1600 1590 1650 1557 1506 1538 Molding temperature 1130 1194 1170 1225 1130 1129 1135 Devitrification temperature 1115 1106 1175 1202 1129 1115 1065 Working temperature range 15 88 -5 23 1 14 70 Specific gravity 2.59 2.58 2.62 2.52 2.59 2.74 2.77

Examples 1 to 9 in Tables 1 and 2 show the present invention.
Is the glass in^Two When poise temperature is below 1600 ℃
It can be easily melted and clarified by electric melting, etc.
You. Ten ^Four Poise temperature is 1200 ° C or less and devitrification temperature is 10^Four 
Moldability is also reduced by lowering the poise temperature by 10 ° C or more.
Easy and suitable for float molding. The strain point of the glass is 570
Good heat resistance above ℃. The coefficient of thermal expansion is 80 × 10^-7/ ℃
The above approximates the coefficient of thermal expansion with the electrode and the thick film. In addition
By reducing the specific gravity of the lath to 2.60 or less, the size has been increased.
Display devices can be made lighter and easier to handle.
Wear. Furthermore, although not indicated, the volume resistivity is 10⁹ Ω.cm or more
Excellent in electrical insulation and substrate glass for display device, especially PD
It is suitable as a substrate glass for P.

[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 display devices, in particular, a substrate glass for PDP, and has a good melting property of glass, and is suitable for melting by a direct current method and molding by a float method, Glass can be manufactured continuously at a low cost, which is advantageous for mass production.

Claims (1)

[Claims] (1) In terms of wt%, SiO ₂ 61-65, Al ₂ O ₃ 9-13, Zr
O ₂ 0.5-3.5, SiO ₂ + Al ₂ O ₃ + ZrO ₂ 71-78, MgO 1-
6, CaO 3-9, SrO 1-5, BaO 0-5, MgO + CaO
_{+ Sr0 + BaO 10~15, Li 2} O 0~3, Na 2 O 7~10, K 2
O 1 to 5, incorporated within a range of _{Li 2 O + Na 2 O +} K 2 O9~14, glass specific gravity of 2.60 or less, the strain point of the glass is 570 ° C. or higher, 10 ⁴ poise temperature of the glass is at 1200 ° C. or less, 10 ⁴ A substrate glass composition for a display device, wherein the temperature difference between the poise temperature and the devitrification temperature is 10 ° C. or more, and the coefficient of thermal expansion of the glass from room temperature to 300 ° C. is 80 × 10 ⁻⁷ / ° C. or more.