JPH0676228B2 - Glass composition for sealing - Google Patents

Description

TECHNICAL FIELD The present invention relates to a glass composition for sealing for hermetically sealing the ends of filters and the like.

[Prior Art] Conventionally, microfiltration filters have been used for food products such as beer and liquor. The end of this filter is a closed system that is hermetically sealed. Although the required characteristics of this hermetic sealant differ depending on the use, glass is generally used because heat resistance and corrosion resistance are required and high reliability is required.

However, the conventional glass has a drawback that it has poor corrosion resistance and a short service life.

[Problems to be Solved by the Invention] An object of the present invention is to solve the above-mentioned problems that the conventional corrosion resistance has drawbacks, and more specifically, as a result of examining the glass composition, We have found a glass composition that can solve the above problems.

An object of the present invention is to provide a glass composition for sealing which eliminates the above-mentioned drawbacks of the prior art and has excellent corrosion resistance.

[Means for Solving Problems] That is, in the present invention, the glass component is substantially composed of 55 to 100% by weight and the refractory filler is 0 to 45% by weight, and the glass powder is substantially represented by SiO by weight. from _{2 60~75% ZrO 2 15~30% La} 2 O 3 0.5~10% Li 2 O + Na 2 O + K 2 O 5~15% MgO + CaO + SrO + BaO 0~5% Al 2 O 3 0~5% TiO 2 0~5% That is, the glass composition for sealing has a thermal expansion coefficient in the range of 60 to 75 × 10 ⁻⁷ / ° C.

In the present invention, the refractory filler is not an essential component, but the strength of the sealed portion can be improved by adding it. However, if its content exceeds 45%, the sinterability of the glass decreases and the airtightness is impaired, which is not preferable. Examples of such refractory fillers include alumina, zircon and zirconia.

The reasons for limiting the glass components in the present invention are as follows.

If the SiO ₂ content is less than 60%, the chemical durability of the glass cannot be ensured, which is not preferable. If it exceeds 75%, the softening point of the glass becomes too high and the glass does not flow at a desired temperature, which is not preferable.
It is preferably 61 to 74%.

ZrO ₂ : If less than 15%, chemical durability is unfavorable. 3
If it exceeds 0%, the glass softening point becomes too high, which is not preferable. It is preferably 16 to 29%.

La ₂ O _3: poor undesirably low chemical durability than 0.5%. If it exceeds 10%, the glass softening point becomes too high, which is not preferable. It is preferably 1 to 9%.

Li ₂ O + Na ₂ O + K ₂ O: If it is less than 5%, glass melting becomes difficult, which is not preferable. If it exceeds 15%, the corrosion resistance of the glass is deteriorated and the coefficient of thermal expansion is increased, which is not preferable. It is preferably 6 to 14%.

MgO + CaO + SrO + BaO: Not an essential component, but used for the purpose of improving the glass solubility. If it exceeds 6%, the corrosion resistance decreases, which is not preferable.

Al ₂ O ₃ : Although not an essential component, it may be used for the purpose of improving corrosion resistance and glass solubility. If it exceeds 6%, the softening point becomes too high.

TiO ₂ : Can be used even if used for the purpose of improving corrosion resistance.
If it exceeds 6%, the softening point becomes too high, which is not preferable.

The thermal expansion coefficient of the glass composition composed of the above is 60 × 10
If it is less than ^-7 / ° C, the difference in thermal expansion between the base material and the filter becomes large, and the adhesive strength decreases, which is not preferable. 75 x
When it is higher than 10 ⁻⁷ / ° C., it is not preferable in the same sense. It is preferably 62 to 73 × 10 ⁻⁷ / ° C.

[Example] Glass raw materials were prepared and mixed so that the target composition was obtained, and the temperature was 1450 ° C.
Dissolve homogeneously at ~ 1550 ° C for 1-5 hours. Then, the obtained molten glass is pulverized into particles or flakes to be pulverized by a ball mill to obtain the composition glass powder shown in Table 1. Next, a refractory filler was added to this and pulverized with a ball mill to obtain the composition shown in the same table. A clay substance such as kaolin or montmorillonite or water is added to this composition to form a slurry, which is applied and formed on the end portion of the ceramic porous body.

Then, this is fired at 1100 ° C. to 1350 ° C. for 1 to 2 hours to bake the glass composition at the end. Table 1 shows the evaluation of the condition after baking.

As is clear from the table, the glass composition according to the present invention has excellent acid resistance and alkali resistance.

The physical properties were measured as follows.

Acid resistance: Immerse in 1N hydrochloric acid held at 90 ° C for 200 hours, measure the decrease in weight at that time, and express it in%.

Alkali resistance: Immerse in 1N caustic soda aqueous solution kept at 90 ° C for 200 hours, measure the decrease in weight at that time, and express it in%.

[Advantages of the Invention] According to the present invention, it is possible to perform sealing with excellent chemical durability as compared with conventional glass.

Claims (1)

[Claims] 1. A glass component consisting of 55 to 100% and a refractory filler of 0 to 45%, which is substantially expressed in weight%, and said glass powder is substantially expressed in weight% SiO ₂ 60 to 75% ZrO ₂ 15 to 30. % La ₂ O ₃ 0.5-10% Li ₂ O + Na ₂ O + K ₂ O 5-15% MgO + CaO + SrO + BaO 0-5% Al ₂ O ₃ 0-5% TiO ₂ 0-5% with a thermal expansion coefficient of 60-75 × A glass composition for sealing in the range of 10 ^-7 / ° C.