JPH0672030B2 - Alkali free glass - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is excellent in heat resistance, chemical resistance, and optical homogeneity, and is widely used, for example, as a material for electronic parts in the field of electronic industry, and particularly by the direct energization method. The present invention relates to an alkali-free glass that can be formed (plate-formed) by electric melting or a float method.

[Conventional technology and its problems]

In recent years, a non-alkali glass substrate in which a thin film of a metal or a metal oxide is formed on the surface of glass has been used as a transparent substrate for a display or the like. These non-alkali glass substrates are required to have the following characteristics in terms of application as a material for electronic components and production.

That is, the heat treatment at a high temperature is performed in the film forming process on the glass substrate, but the high heat resistance that can withstand it is also
The thin film formed on the substrate is etched by a chemical solution such as acid or alkali in the patterning process, but chemical resistance that does not corrode the substrate glass itself, and if bubbles, phase separation, and striae are present in the glass Optical homogeneity is required because it causes optical defects in displays and the like.

In addition, in industrial production, it must be easy to melt and easy to mold, especially electric fusion by the direct current method that can be continuously melted with little pollution by atmosphere, furnace material, etc., surface smoothness It is desired that the glass composition has excellent properties and is suitable for continuous molding by float molding.

Conventionally, as alkali-free glass which is relatively easy to melt and suitable for mass production, SiO ₂ , Al ₂ O ₃ and B as typified by E glass are used.
A glass containing a CaO or MgO component as a component composed of ₂ O ₃ is known. However, for example, in the manufacturing process of thin film transistors, liquid crystal displays, etc., hydrofluoric acid-based solution is often used as an etching agent in order to improve the efficiency of thin film patterning on a glass substrate. On the other hand, the known glass is corroded by the hydrofluoric acid-based solution to cause an etching pattern or cloudiness on the surface of the glass, so that it cannot be used as a transparent substrate.

Japanese Examined Patent Publication No. 50-22568 and Japanese Unexamined Patent Publication No. 1-201041 describe SiO ₂ -Al ₂ O ₃ -B.
Mg in ₂ O ₃ skeletal components (hereinafter these are collectively referred to as MO _x )
Glass compositions containing O, CaO, BaO, etc. and suitable for electronic parts, particularly substrate glass, have been disclosed. All of them are B ₂ O ₃
Since it contains a large amount of ZrO ₂ and does not contain ZrO ₂ , chemical resistance such as heat resistance and acid resistance is insufficient.

In Japanese Patent Laid-Open No. 63-176332, CaO is an essential component in the MO _x system, MgO, Ba
A glass composition suitable for an electronic material substrate containing O, ZrO _{2 and the} like as an optional component is disclosed, but Al ₂ O ₃ is excessively contained, and B ₂ O ₃ is contained.
_Since it contains too little ₃ and contains too little BaO, it has a difficulty in melting and has a high devitrification tendency.

JP-A-63-74935 discloses a glass composition suitable for an electronic material substrate containing CaO, BaO, etc. in MO _x , but since it does not contain ZrO ₂ , it has chemical resistance such as acid resistance and hydrofluoric acid resistance. It is inferior, improves meltability during glass melt molding, suppresses devitrification to facilitate molding, and unlike other divalent components, does not contain MgO that does not significantly increase the thermal expansion coefficient of glass. There is a problem in.

Japanese Examined Patent Publication No. 1-46460 relates to the invention of the present applicant, and MO _x and Mg
O and ZnO are essential to provide a glass composition having a low expansion and suitable for a photomask, but Al ₂ O ₃ is excessive and inferior in meltability, and by containing ZnO, a metal electrode during electric melting And reacts with it to erode, and is easily volatilized and contaminated in a reducing atmosphere during the float molding.

The present invention solves the problems of the above-mentioned conventional glass compositions,
Acid resistance (hereinafter referred to as inorganic resistance other than hydrofluoric acid, organic acid),
It is an object of the present invention to provide an alkali-free glass having optical homogeneity, which is excellent in hydrofluoric acid resistance and heat resistance, and which is easily melt-molded in glass, particularly electric melting by a direct current method, and continuous molding by a float method.

[Means for solving problems]

The present invention is in terms of weight percent, SiO ₂ 56-60, Al ₂ O ₃ 10-12, B ₂ O
_{3 7~9, ZrO 2 0.8~3, CaO7~12} , MgO0.8~2, BaO6~
13, where CaO, MgO and BaO total 19 to 24, which are substantially alkali metal oxides and PbO, ZnO, TiO ₂ , As
_It consists of alkali-free glass that does not contain ₂ O ₃ , Sb ₂ O _{3 or} SO ₃ .

In the present invention, SiO ₂ is the main component of glass, and if it is less than 56%, the acid resistance and hydrofluoric acid resistance of the glass decrease. If it exceeds 60%, the high temperature viscosity of the glass melt becomes high, so that the meltability becomes poor, the tendency of glass to pass through increases, and particularly SiO ₂ -based crystals tend to precipitate. Therefore, the range of 56-60% is preferable.

Al ₂ O ₃ has the effect of suppressing the initiation of phase separation of the SiO ₂ system and B ₂ O ₃ -RO system and homogenizing it, but if it is less than 10%, the action is insufficient, and if it exceeds 12%. The meltability is deteriorated, the devitrification tendency is increased, and SiO ₂ —Al ₂ O ₃ —CaO (—MgO) -based crystals are likely to precipitate. In addition, the hydrofluoric acid resistance of the glass decreases. Therefore 10 ~
12% range is good.

B ₂ O ₃ lowers the high temperature viscosity of the glass melt and improves the meltability. Further, glass exhibits durability against hydrofluoric acid. If it is less than 7%, these effects are small, and if it exceeds 9%, the heat resistance of the glass is lowered and the acid resistance is also lowered. Therefore, 7-9
The range of% is good.

ZrO ₂ itself has a higher melting point than SiO ₂ , but CaO, MgO, Ba
Eutectic at a low temperature due to the coexistence of O. The presence of a small amount of ZrO ₂ suppresses the devitrification tendency of the glass melt. It also improves the heat resistance, acid resistance, and hydrofluoric acid resistance of the glass. However, if it is less than 0.8%, these effects cannot be sufficiently obtained, and if it exceeds 3%, the devitrification tendency increases and the meltability deteriorates. Therefore, the range of 0.8 to 3% is preferable.

The _{SiO 2, B 2 O 3,} Al 2 O 3 , and acidic to neutral oxides such as ZrO _2, in particular SiO _2, Al ₂ O _3, relative to ZrO _2, basic oxides described below CaO, Melting is facilitated by making MgO, BaO, etc. coexist and acting as a solvent during glass melting. That is, CaO reduces the high temperature viscosity of the glass melt, improves the meltability, and suppresses the tendency of devitrification. 7
If it is less than 12%, these effects are insufficient, and if it exceeds 12%, the heat resistance of the glass is lowered, and the above-mentioned phase separation is likely to occur. Therefore, the range of 7 to 12% is preferable.

MgO improves meltability without increasing the expansion coefficient of glass and is effective in suppressing devitrification, but if it is less than 0.8%, its effect is small, and if it exceeds 2%, it is particularly pitted by hydrofluoric acid-based solution. White turbidity is likely to occur, and SiO ₂ -Al ₂ O ₃ -MgO-based crystals are likely to precipitate, which increases the devitrification tendency of the glass. Therefore 0.8
The range is up to 2%.

BaO improves the meltability in the coexistence with CaO and suppresses the devitrification tendency of the glass, but if it is less than 6%, its effect is insufficient.

If it exceeds 13%, the acid resistance of the glass decreases, and the high temperature viscosity of the glass melt increases, resulting in poor meltability. Therefore 6 ~
A range of 13% is good.

Further, within the above composition range, CaO + MgO + BaO is 19 to 2
By maintaining 4%, while maintaining the meltability of the glass in a good range, the viscosity-temperature gradient is moderate and the moldability is good, heat resistance, acid resistance and hydrofluoric acid resistance are excellent, and devitrification tendency It is possible to obtain a small non-alkali glass. When CaO + MgO + BaO exceeds 24%, the meltability is improved, but especially the acid resistance and hydrofluoric acid resistance are poor. If it is less than 19%, the acid resistance and the hydrofluoric acid resistance are improved, but the meltability is deteriorated, the devitrification tendency is increased, and the electric resistance during melting is increased, which is not suitable for electric melting. Therefore, it is 19 to 24%, more preferably 20 to 22%.

In the present invention, the alkali metal oxide lowers the heat resistance of the glass, and in particular, when the metal thin film or the like is formed on the glass as an electronic component material, the alkali metal ion deteriorates the surface emission film property, so that it is substantially contained. It is mandatory not to.

In addition, in order to enable electric fusion by direct energization, it is necessary to avoid forming a eutectic body by reacting with a commonly used electrode such as molybdenum, so that PbO and ZnO having reactivity are used. It is essential that it does not substantially contain As ₂ O ₃ , Sb ₂ O ₃ , SO ₃ or the like as a fining agent.

Furthermore, in order to enable mass production by the float molding and to prevent volatilization under a reducing atmosphere such as nitrogen and hydrogen to contaminate the furnace material and atmosphere or to cause surface defects on the glass, and to color the glass Volatile components such as PbO, ZnO, TiO ₂ , As ₂ O ₃ , Sb ₂ O ₃ , SO ₃
It is essential that the reaction coloring component (1) is not substantially contained.

Incidentally, the reactive component with the alkali metal oxide or the electrode for electric current melting, the reaction with the reducing atmosphere, the volatile component and Sr
0.1 wt% O, Fe ₂ O ₃ and MnO ₂ as other trace impurities
% Or less is not a hindrance to the present invention.

〔Example〕

A batch raw material consisting of silica sand, aluminum hydroxide, boric acid, calcium carbonate, barium carbonate, zinc white, titanium oxide, zircon sand, and magnesium carbonate prepared to have the target composition shown in Table 1 was filled in a platinum crucible and charged with electricity. In the furnace
It was melted by heating at 1550 ° C. for about 6 hours. Next, the molten glass was poured into a mold, held in a nitrogen gas and hydrogen gas atmosphere furnace to form a glass block having a size of about 320 × 220 × 35 mm, and gradually cooled. The thermal expansion coefficient, glass strain point, high temperature viscosity (temperature of 10 ² poise), acid resistance, and hydrofluoric acid resistance of these glass samples were measured, and observed visually and under a mirror for the colored state and the presence or absence of phase separation. The results are shown in Table 1.

The coefficient of thermal expansion is measured with a thermal expansion meter and is from room temperature to 300 ° C.
The glass strain point (10 ^14.5 poise) was measured by a known beam bending method, and the high temperature viscosity was measured by a sphere pulling method. Acid resistance was measured by immersing the sample in 1 / 100N HNO ₃ at 95 ° C for 20 hours and measuring the weight loss.
After being immersed in the solution at 25 ° C. for 5 minutes, the weight loss was measured.

Examples No. 1 to No. 11 in Table 1 are glasses according to the present invention, having a coefficient of thermal expansion as low as 1/2 or less of soda-lime type (90 to 100), a strain point of 630 ° C. or more, and excellent heat resistance, 10 ² Poise temperature, that is, melting equivalent temperature is around 1550 ℃, it is easy to melt in industrial production, acid loss resistance is 0.2 or less, no turbidity of the naked eye is observed, hydrofluoric acid resistance loss is 1.0 order or less No brilliance or the like due to the degradable surface layer was observed, neither coloring due to the reducing gas atmosphere nor white turbidity due to phase separation was observed at all.

On the other hand, in Comparative Examples No1 to No7, No1 is inferior in strain point and acid loss resistance, No2 is colored, No3 is phase separation, No4 is phase separation and coloration, and the strain point is low, No5, No7 is 10 ^2. Poise temperature is as high as around 1600 ℃, inferior in meltability, and in addition No7
No. 6 has a low strain point and is inferior in acid resistance and hydrofluoric acid resistance, and No. 6 has a high thermal expansion coefficient and is inferior in hydrofluoric acid resistance.

[Effects of the Invention] The alkali-free glass of the present invention is excellent in heat resistance, acid resistance, and hydrofluoric acid resistance. Therefore, a metal or metal oxide thin film is formed on the glass surface, and the thin film is etched to form a pattern. It is suitable as a glass substrate for forming. further,
Since it has excellent meltability by the direct current method of glass and formability by the float method, it is possible to continuously manufacture homogeneous glass without phase separation, coloring, etc. at low cost and is suitable for mass production. Has the effect.

Claims (1)

[Claims] 1. SiO ₂ 56-60, Al ₂ O ₃ 10-1 in weight%
2, B ₂ O ₃ 7-9, ZrO ₂ 0.8-3, CaO 7-12, MgO 0.8-2,
BaO6 ~ 13, but consisting of CaO, MgO and BaO total 19 ~ 24, substantially alkali metal oxides and PbO, ZnO, Ti
A non-alkali glass characterized by containing no O ₂ , As ₂ O ₃ , Sb ₂ O _{3 and} SO ₃ .