JPH0426526A - Low thermal expansion glass composition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a low expansion glass composition suitable for glass coating of cement molded bodies by glazing, thermal spraying, etc.

<Prior Art> Glass compositions for enameling that are baked at high temperatures of 800 to 1000°C have been known. Although this has excellent surface performance after baking, it cannot be used for heat-sensitive substrates.
In addition, heat may increase the amount of change in the substrate, resulting in poor dimensional accuracy of the resulting enamel product.

On the other hand, low melting point glass compositions often have inferior surface performance compared to the glass film formed by the above-mentioned high melting point glass compositions, and -a, many low melting point glass compositions have high coefficients of thermal expansion. However, when a cement-based molded body, which often has a low expansion coefficient, is used as a substrate, there is a problem that the coefficient of thermal expansion tends to be incompatible, and furthermore, it is difficult to adjust these (Japanese Patent Laid-Open No. 56-26744, Japanese Patent Application No. 63-117926)
.

In addition, a manufacturing method for enameled building materials is known in which natural stone powder such as Oya stone or granite is added to the glaze (Japanese Patent Application Laid-Open No. 56-13
No. 478). This is a means to obtain a natural stone-like appearance, and the base material is a metal plate with a high coefficient of thermal expansion, and cannot be used for a base material with a low coefficient of expansion, such as a cement-based molded body.

<Problems to be Solved by the Invention> The conventional low-melting point glass compositions described above often have a high coefficient of thermal expansion, poor surface properties, and contain large amounts of harmful substances.

Therefore, attempts have been made to solve this problem by combining various components, but it requires complicated processes and time to achieve both sufficient film surface performance and matching of the coefficient of thermal expansion with the substrate. Also,
Even with such a method, there are limits to the reduction of the coefficient of thermal expansion, and there are many restrictions, particularly when using a substrate with a low coefficient of expansion such as a cement molded body.

<Means for Solving the Problems> In view of the current state of low melting point glass compositions as described above, the present inventors have determined that the heating conditions (firing temperature, time, etc.) can be improved without changing the heating characteristics of the glass composition. As a result of intensive research into low-expansion glass compositions that can maintain good film surface performance (water resistance, acid resistance, alkali resistance, weather resistance, etc.) without changing the properties (water resistance, acid resistance, alkali resistance, weather resistance, etc.) without changing the We succeeded in obtaining a composition that satisfies the requirements.

That is, the composition of the present invention is characterized by adding 1 to 30% by weight of low expansion aggregate with a particle size range of 50 to 500 μm to a low melting point glass composition.

The low melting point glass composition used in the present invention has a thermal expansion coefficient of 9 x 10-'' at a firing temperature of about 700°C or less.
/'C or less, there are no restrictions on composition or other matters. If the firing temperature and coefficient of thermal expansion are larger than the above-mentioned values, it is difficult to actually use it for cement-based molded bodies.

The low expansion aggregate used in the present invention may be one such as quartz glass, aluminum titanate, spodumene, cordierite, etc., as long as its coefficient of thermal expansion is lower than that of the glass frit used. Preferably, the coefficient of thermal expansion of the glass frit is 273 or less, and 2
When it is larger than /3, the effect of reducing the coefficient of thermal expansion is low.

However, the hue and appearance may be affected depending on the combination with the glass frit used, so it is necessary to make an appropriate selection from these viewpoints in actual use.

Regarding the particle size, a particle size range of 50 to 500 μm is suitable. If it is finer than this, the effect of reducing the coefficient of thermal expansion will be low, and if it is too coarse, it will tend to reduce the smoothness of the film.
More preferably, the particle size range is from 100 to 300 μm. The amount added is 1 to 30% by weight, particularly preferably 5 to 20%, based on the glass frit. If the amount added is too small, the effect of reducing the coefficient of thermal expansion will be low, and if it exceeds 30%, the fluidity of the glaze during enameling firing will decrease, and there is a possibility that it will not be able to fully demonstrate its function as a glaze. It is.

As a method for applying such a glass composition containing low expansion aggregate to a substrate, in addition to spraying with a spray gun, commonly used methods such as dipping can be employed. After applying the glass composition, drying and firing can be carried out under the same conditions as for ordinary glazing.

Furthermore, when applying other coatings such as thermal spraying, it can be used under the same conditions as when using a glass composition without additives.

<Examples and Comparative Examples> As a basic frit, the composition of which is shown in Table 1, 3557 manufactured by Nippon Ferro Co., Ltd. (thermal expansion coefficient 6.4 x 10-6/'
A C1 firing temperature of 600 to 800°C (deflection point of 497°C) was used.

Using an aluminum crucible, the raw material mixture with the composition shown in Table 1 was heated to 600°C in an electric furnace for 1 hour, and then heated to 600°C for 1 hour.
After being maintained at 00°C for 1 hour, it was cooled to obtain a glass composition. The method for measuring the physical properties of the obtained glass composition is as follows. In addition, water resistance was measured as surface performance.

A rod-shaped glass composition with a thermal expansion coefficient of 0 and a diameter of about 5 cm and a length of about 20 cm was used as a sample,
The expansion was measured by a displacement meter at a temperature increase of about 10° (:/sin).

A sample of approximately 4.2 g of a pulverized water-resistant glass composition having a particle size of 420 to 590 t1m was heated in 80M1 of purified water for 1 hour, and then the weight loss rate was measured.

No. the law of nature table (Effect of the invention> The glass composition of the present invention has the following effects.

(1) A film can be obtained under the same heating conditions as a glass composition to which no aggregate is added.

(2) A film having water resistance equivalent to a glass award film obtained using a glass composition to which no aggregate is added can be obtained.

(3) The coefficient of thermal expansion of the glass composition can be reduced, and the coefficient of thermal expansion of the glass composition can be adjusted by adjusting the amount of aggregate added.

(4) It can also be used for base materials that are weak at high temperatures and have low expansion, such as cement-based molded bodies that were conventionally used as plates.

Patent applicant: Asahi Kasei Industries, Ltd.

Claims (1)

[Claims] Low melting point glass composition with particle size range of 50 to 500 μm
A low expansion glass composition characterized in that 1 to 30% by weight of low expansion aggregate is added.