JPH0432010B2 - - Google Patents

Description

[Detailed description of the invention]

[Object of the Invention] (Industrial Application Field) The present invention relates to a sealing glass, and particularly to a sealing glass suitable for sealing glass used for lighting. (Prior art) Low melting point sealing glasses are generally used for bonding or coating glass, ceramics, or metals, and include PbO-B ₂ O _3- based and PbO-B ₂ O ₃ -ZnO-based low melting glasses. It has been known. Among these, the sealing glass that is used for sealing soda-lime glass or potash-soda-lead glass that is normally used for lighting has a coefficient of thermal expansion (hereinafter referred to as α) of 88 to 100 × 10. It is required that the welding can be carried out at ^-7 /°C and below 450°C so that glass members such as tubes do not deform during welding, and it is desirable that the welded part be transparent. Examples of sealing glasses that can be coherently fused with soda lime glass include those disclosed in Japanese Patent Publication No. 7977/1983 and Japanese Patent Application Laid-open No. 17607/1989. (Problems to be Solved by the Invention) The sealing glass described in Japanese Patent Publication No. 56-7977 has the drawback that the fused portion is colored black because it contains copper oxide, which is unfavorable in terms of appearance. .
Furthermore, the crystalline solder and glass described in JP-A-53-17607 are difficult to process after fusion and take a long time to crystallize, making them unfavorable in terms of workability. In general, if you try to lower the melting point of low-melting point glass, a tends to increase, and if the difference in α between the mating material and the material to be fused increases to some extent, the difference in the amount of shrinkage between the two will occur while the temperature drops after welding. Cracks occur at the fused part. Therefore, when developing this type of glass, the problem was how to lower the melting point without increasing α. Various low melting point glasses have been proposed, such as the glass described in the above publication, but a low melting point sealing glass that is ideal for sealing glasses mainly used for lighting as described above has not been put into practical use. do not have. An object of the present invention is to provide a transparent sealing glass which can be fused at a temperature of 450 DEG C. or less and has an a of 88 to 100.times.10.sup.- ⁷ / DEG C. [Structure of the Invention] (Means for Solving the Problems) The present inventor has conducted research in consideration of the above problems.
It has been found that the objective can be achieved by introducing thallium oxide and alkali into PbO-B ₂ O ₃ -ZnO glass. That is, the present invention uses PbO40~80 in weight percentage.
%, _Tl2O5 ~30%, PbO+ _Tl2O65 ~85%,
B ₂ O ₃ 10-20%, Li ₂ O + Na ₂ O + K ₂ O 0.1-5%,
This is a sealing glass characterized by having a composition of 1 to 13% ZnO, 0.5 to 5% SiO ₂ , and 0.1 to 5% Al ₂ O, and having α of 88 to 100×10 ⁻⁷ /°C. Next, the reason for limiting the values of each component of the glass will be explained. When PbO is less than 40%, the viscosity increases and the melting temperature becomes high, and when it exceeds 80%, α becomes large and devitrification tends to occur. When Tl ₂ O is less than 5%, the fusion temperature becomes high;
If it exceeds 30%, devitrification tends to occur. For B ₂ O ₃ , α becomes large when it is less than 10%, and at 20%
If it exceeds this value, the viscosity increases and processing becomes difficult. It is desirable to add at least one type of alkali metal oxide to reduce glass viscosity, but if it is less than 0.1%, it will not have this effect, and if it exceeds 5%, α will become too large and cause cracks in the processed product. . ZnO makes the viscosity relatively low without increasing α, but if it is less than 1% it has no effect, and if it exceeds 13% it tends to devitrify. SiO ₂ is effective in improving scientific durability, but
If it is less than 0.5%, there is no scientific durability improvement effect.
If it exceeds 5%, the viscosity increases and it becomes difficult to melt. Al ₂ O ₃ is added to prevent devitrification, but at 0.1%
If it is less than 5%, there will be no effect, and if it exceeds 5%, the viscosity will increase and processability will deteriorate. (Function) The low melting point glass manufactured with the above composition has a temperature of 450°C.
Can be fused at the following temperatures, and α = 88 ~
A transparent glass with a temperature of 100×10 ^-7 /°C is obtained. (Example) Next, an example of the present invention will be described. No. in the table
Glasses No. 1 to 3 are examples of the present invention, and glass No. 4 is a reference example of PbO-B ₂ O ₃ glass. In addition, the glass composition in the table is shown in weight percentage.

[Table] After mixing the raw materials so as to have the glass composition shown above, this was placed in a platinum crucible and heated to 900℃ in an electric furnace.
After heating and melting at 1000°C, the glass was poured into a mold and slowly cooled to obtain the glass of the example. This glass was cut into 5 mm squares, placed on a soda lime glass plate, and
After heating at ℃ for 5 minutes, it was taken out and its contact angle was measured. The smaller the value of the contact angle, the better the flow, and although the glasses of Examples Nos. 1 to 3 of the present invention had a relatively small α of 90 to 98×10 ^-7 /°C, It can be seen that the contact angle is a sufficiently small value and there is good fluidity. Furthermore, there was no devitrification or coloration on the adhesive surface, and no cracks were observed. On the other hand, the glass of Reference Example No. 4 had a small contact angle and good fluidity, but α was large at 110×10 ^-7 /°C, and as a result of observing the bonded surface, cracks were observed. As can be seen here, the glass of the example of the present invention has α of 100×10 ^-7 /°C or less, and a sufficiently good sealing state is obtained at 450°C. Above, we have talked about fusion with soda-lime glass, but we have also discussed fusion with other glasses such as potash, soda, and lead-based glasses, which have α almost the same as soda-lime glass, as well as metals, ceramics, etc. Needless to say, it can be applied to (Effects of the Invention) As described above, since the glass of the present invention can be fused at a temperature of 450°C or lower, when used for sealing glass used for lighting, it deforms glass members such as tubes. This sealing glass is extremely suitable for sealing glass members for lighting, since it can be sealed without any damage, and the sealed portion does not devitrify or color, so it does not impair the brightness or aesthetics of lighting.

Claims (1)

[Claims] 1 In weight percentage, PbO40~80%, _Tl2O5 ~30
%, PbO + Tl ₂ O 65-85%, B ₂ O ₃ 10-20%, Li ₂ O
+ _Na2O + _K2O0.1 ~5%, ZnO1~13%, SiO2 _0.5
5%, _{Al2O3 0.1} to 5%, and a thermal expansion coefficient of 88 to 100×10 ^-7 /°C.