JPH0446908B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an aluminosilicate glass suitable for electronic equipment substrate glass that can be manufactured continuously. Thin plates of 0.3 to 1.0 mm are used for substrate glass for LCDs, etc., but in order to continuously and efficiently manufacture these thick plate glasses from a glass melting chamber, it is necessary to
The plate manufacturing methods used are the Colburn method, the Fourcor method, and the float method. The glass composition most suitable for plate manufacturing using the above method has traditionally been used for architectural,
Soda-lime silica glass has been used for vehicles, etc., but since glass with this composition has a high alkali content, when used as substrate glass for electronic and electrical product parts such as liquid crystal substrates, it is difficult to remove alkali from the substrate glass. The drawback was that elution deteriorated performance. In order to improve this drawback, a method has been adopted in which ethyl silicate is used on the surface of a soda lime silica glass substrate to form a SiO ₂ film to prevent alkali elution from the substrate glass. On the other hand, there are glass compositions that have a low alkali content and do not require coating with SiO ₂ film, which has low alkali elution, but it is difficult to make plates using the three methods mentioned above, and after making plates using the roll-out method, the surface must be polished. The substrate glass is made using the roll-out method, then polished and then reheated and stretched.
Make 0.3-1mm thick glass and use it as substrate glass,
Alternatively, glass with a thickness of 0.3 to 1.0 mm is made using a very special plate-making method that is not suitable for mass production (for example, the flow-down method of Japanese Patent Publication No. 46-24909). However, in these cases, even if SiO ₂ film coating is not necessary, the benefits are halved due to the low productivity of the substrate glass. The present invention solves these disadvantages and provides an aluminosilicate glass that can be produced continuously in large quantities by the Fourcor method, the Colburn method, or the float method, and does not require a coating to prevent alkali elution. The aluminosilicate glass according to the present invention is expressed in weight percent: SiO ₂ 50-62% B ₂ O ₃ 2-5% Al ₂ O ₃ 10.5-18% MgO 0.5-7% CaO 4-13% BaO 0-7 % ZnO 3-10% Li ₂ O 0-2% Na ₂ O 0-10% K ₂ O 0-10% However, Li ₂ O + Na ₂ O + K ₂ O = 3.8-11% as the basic component, T _W −T _L >−30°C. The reasons for limiting the composition in the present invention are as follows. SiO ₂ is the main glass-forming oxide in the glass of the present invention, but if it exceeds 62%, the viscosity of the glass increases and its solubility deteriorates. Moreover, if it is less than 50%, the chemical durability of the glass will be significantly impaired, so 50% is set as the lower limit. Preferred range is 54-58
%. B ₂ O ₃ lowers the high-temperature viscosity of glass and makes it easier to melt, but B ₂ O ₃ alone or in combination with an alkali component easily volatilizes from the glass base, causing striae and stent formation when glass is formed. This may result in disadvantages such as: As the content of B ₂ O ₃ increases, the volatilization from the glass substrate becomes more intense, so the upper limit of B ₂ O ₃ is set at 5%. If B ₂ O ₃ is less than 2%, it will be difficult to melt the glass, so 2% is the lower limit. The preferred range is 4-5%. In the case of aluminosilicate glass, Al ₂ O ₃ improves the stability and chemical durability of the glass. If it exceeds 18%, the viscosity of the glass will increase and its solubility will deteriorate, and if it is less than 10.5%, its chemical durability will deteriorate.
The preferred range _{of Al2O3} for glass stabilization is 13-15%. MgO improves the chemical durability of glass and reduces the coefficient of thermal expansion, but MgO
If it exceeds 7%, the devitrification temperature of the glass increases and the solubility deteriorates. Moreover, if it is less than 0.5%, the chemical durability of the glass will decrease. Preferably it is 0.5-4%. CaO lowers the high-temperature viscosity of glass and makes it easier to melt the glass, but when CaO exceeds 13%, the devitrification temperature of the glass increases, and when it is less than 4%, it becomes difficult to melt the glass. BaO is not an essential ingredient, but 5% BaO
When added to a certain degree, the devitrification temperature of the glass decreases significantly,
Makes molding easier. However, if it exceeds 7%, the chemical durability of the glass will deteriorate. ZnO reduces the high-temperature viscosity of glass and facilitates glass melting, but 10
%, the slope of the temperature-viscosity curve of the glass becomes steeper, and the viscosity changes significantly with minute temperature changes, making molding difficult. Moreover, if it is less than 3%, the high temperature viscosity will not be lowered sufficiently and dissolution will become difficult. Preferably the range is 5
~7%. Li ₂ O, Na ₂ O, and K ₂ O all promote glass melting, but considering that Li ₂ O is an expensive raw material, the upper limit is set at 2%. _Na2O
If the content of K and K ₂ O exceeds 10%, the chemical durability of the glass will decrease and the amount of alkali elution will increase, so the upper limit for each is set at 10%. However, Li ₂ O + Na ₂ O
If +K ₂ O is less than 3.8%, the melting of the glass will deteriorate, so 3.8% is set as the lower limit. Also, the total amount of the three parties is 11
If it exceeds 11%, the chemical durability will deteriorate and the amount of alkali elution will increase, so the upper limit is set at 11%. 3.8～
9% is preferred. In addition to the above-mentioned basic components, impurities inevitably mixed in from the glass raw materials, such as TiO ₂ and Fe ₂ O ₃ , may be contained in a content of 0.5 or less. In addition, Sb ₂ O ₃ , As ₂ O ₃ , So ₃ , F ₂ ,
Cl ₂ or the like may be contained in an amount of 1% or less. Furthermore, a small amount of oxides commonly used for coloring glass, such as MnO ₂ , Cr ₂ O ₃ , CoO, NiO, CuO, etc., may be included. The reasons for limiting each component have been described above, but the aluminosilicate glass according to the present invention is a glass suitable for continuous sheet manufacturing using the Fourcor method, the Colburn method, and the _float method. Temperature (T _W ) relationship is T _W ×T _L ＞−30℃
is required, and it is preferable that T _W ≧ T _L . Next, the effects of the present invention will be explained based on Examples. No. 1 to No. 12 shown in Table 1 and Comparative Example 1,
Make batches with the proportions necessary to obtain glasses with each of the target compositions in 2, melt them in a platinum crucible at 1450℃,
It was poured into a stainless steel mold, molded, and then slowly cooled. The values of devitrification temperature (T _L ), working temperature (T _W ), and T _W - T _L of the various glasses mentioned above are as shown in the table.
All of the examples according to the present invention have excellent alkali elution resistance and also have temperature characteristics of T _W −T _L >−30°C.
On the other hand, as shown in Comparative Examples 1 and 2, the conventional typical alkali elution-resistant glass has T _W −T _L
<-30° C., which is a temperature characteristic unsuitable for large-scale continuous plate manufacturing, and the commercially available float glass composition of Comparative Example 3 has an alkali elution amount reaching about 10 times. Therefore, the glass of the present invention can be manufactured continuously in large quantities,
It has also been found to be excellent in alkali elution resistance, making it an excellent glass for substrates of electronic equipment. The devitrification temperature T _L used in the above explanation was determined as follows. Crush the glass and pass it through a 1680 μm sieve.
The glass particles held on a 1190 μm sieve were placed over a number of 1 mm diameter holes drilled in a row on a platinum board, and placed in a furnace whose temperature was set to have an appropriate temperature gradient in the length direction of the boat. Hold for 1 hour. After taking the platinum boat out of the furnace and letting it cool naturally,
The glass grains on the platinum boat were observed using a microscope, and the highest temperature at which devitrification occurred was defined as the devitrification temperature. Further, the working temperature (T _W ) is the temperature at which the viscosity of the glass becomes 10 ⁴ poise. The amount of alkali elution was measured according to JISR-3502, and 1 ml of sample glass was crushed to a particle size of 250 to 420 μm.
This is the value obtained by analyzing the amount of alkali dissolved in water after boiling it in 50 ml of water at 100°C for 60 minutes.

【table】

【table】

【table】

Claims (1)

[Claims] 1. SiO ₂ 50 to 62%, B ₂ O _{3 2} to 5%, Al ₂ O ₃ 10.5 to 18% by weight.
%, MgO0.5~7%, CaO4~13%, BaO0~7
%, ZnO3~10%, _Li2O0 ~2%, _Na2O0 ~10%,
It has basic components of K ₂ O 0 to 10%, Li ₂ O + Na ₂ O + K ₂ O = 3.8 to 11%, and T _W −T _L > −30°C (however,
T _W indicates the working temperature, and T _L indicates the devitrification temperature. ) Aluminosilicate glass. 2 Expressed in weight%: SiO ₂ 54-58%, B ₂ O ₃ 4-5%, Al ₂ O ₃ 13-15
%, MgO0.5-4%, CaO7-11%, BaO0-5
%, ZnO5~7%, _Li2O0 ~1%, _Na2O3 ~9%,
_K2O0 ~3%, and _Li2O + _Na2O + _K2O3.8 ~9
Aluminosilicate glass according to claim 1 having a basic composition of %.