JPH0764659B2 - Ceramic product suppressing base-silica reaction and method for suppressing the reaction - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a ceramic product containing a silica component that is reactive with a basic component, in which a base-silica reaction is suppressed; and a ceramic product in which the base-silica reaction has progressed. The present invention relates to a method for suppressing the progress of the reaction in a product. INDUSTRIAL APPLICABILITY The present invention is extremely useful for improving the quality of the ceramic product which may cause cracks, breakage and surface contamination due to the base-silica reaction.

Conventional Technology and Problems Basic / silica-reactive ceramic products represented by ceramic products form alkali / silica-reactive silica components during sintering and firing. The reactive ceramic reacts with an alkaline component (for example, with an alkaline component contained in seawater or with an alkaline component contained in a cement mortar as a base on which a ceramic product is adhered) to produce an alkali-silica reaction product. Form. The expansion of the alkali-silica reaction product presents a major problem of forming cracks and fractures and its surface precipitation forming surface contamination. Conventionally, to reduce this problem,
(A) Reducing the amount of reactive silica component in the raw material,
(B) It was necessary to make the ceramic product non-water-absorbing by high temperature firing. However, in the above method (a), the raw material is slightly expensive and the quality of the feed material is uncertain, which is difficult. The above method (b) is disadvantageous from the viewpoint of thermal economy and furnace, and tends to limit raw materials.

Heretofore, a simple means for improving the reactivity of such a base / silica reactive ceramic product has not been solved. The main object of the present invention is to provide means for easily solving the above problems.

Unexpectedly, the present inventors have unexpectedly contacted ozone-containing water (hereinafter sometimes referred to as O ₃ water) with the reactive silica component in the above-mentioned base / silica reactive ceramic product. It has been found that by doing so, the surface structure of the silica component is modified and stabilized for a long period of time and its reactivity is suppressed.

Therefore, according to the present invention, a water-absorbing mineral ceramic product containing a silica component and / or a silicate component, which is reactive with a basic component, is contacted with ozone in the presence of water to form a reaction site of the reactive silica component. Provided is a ceramic product obtained by modification, which suppresses a base-silica reaction.

INDUSTRIAL APPLICABILITY The present invention can be advantageously applied to the ceramic product in which the base / silica reaction has progressed, and to suppress the progress of the reaction.
Therefore, according to the present invention, the base / silica reaction product appearing on the surface of a ceramic product containing a silicic acid component and / or a silicate component reactive with a basic component is removed,
There is provided a method for suppressing the progress of a base-silica reaction in a ceramic product, which comprises allowing ozone-containing water to permeate into a portion of the ceramic product where the reaction product appears.

Detailed Description of the Invention (1) Examples of base / silica-reactive ceramics Ceramic products to which the present invention is advantageously applied are typically porcelain, stoneware and most porcelain products.
The 24-hour immersion water absorption rate in the case of the water-absorbent ceramic product is
About 0.2% or more, usually about 0.5% or more and typically about 1
% Or more. As the basic component of the ceramic product, the alkaline component particularly participates in the base-silica reaction.
Examples of the reactive silica component include silica minerals such as opal, cristobalite, tridymite, volcanic glass, and chalcedony, and synthetic materials corresponding to the surface forming a glass structure. Generally, igneous rock materials and glass powder are also exemplified. It should be noted that silicates or other inorganic raw materials that become alkali-silica reactive upon firing are also included.

(2) Ozone As ozone used in the present invention, ozone obtained from an ozone generator utilizing silent discharge or electrolysis can be advantageously used. For example, ozone is inexpensively obtained by silently discharging oxygen or dry air with an AC voltage.
The concentration (% by weight) of the O ₃ water used (which may be an aqueous or supersaturated aqueous solution of ozone or ozone-containing water such as ozone-containing steam) is generally about 0.02% or more and about 0.02%.
Is in the range of about 3%, usually about 0.05 to 2%, and even higher concentration is possible in the case of ozone-containing water vapor. The ozone supersaturated aqueous solution is obtained by introducing ozone or an ozone-containing gas into water under pressure. The above-mentioned ozone-containing water vapor is obtained by mixing ozone or an ozone-containing gas with, for example, saturated water vapor, and the ozone concentration with respect to water can be as high as about 20 to 30%. For contact treatment with O ₃ water,
Immersion in O ₃ water (for example, 0.5 to 2% concentration for several tens of minutes or more)
Or can be sprayed with O ₃ water. When a supersaturated aqueous solution of O ₃ or water vapor containing ozone is used, it is generally preferable to seal the container for the contact treatment. Also, the ceramic product to be contacted is placed in a container, and (a) ozone-containing water vapor is continuously introduced, or (b) water is added to dip or wet the substance, and then ozone or ozone is placed in the container. It is also a preferable treatment method to continuously introduce the ozone-containing gas.

In these cases, it is generally preferable to wash the treated ceramic product with water after the contact treatment,
No need to wash with water. In addition, in order to mitigate the effect of O ₃ , a small amount (for example, 2/3 or less equivalent to ozone equivalent of O ₃ water) of a reducing compound (eg sulfite or nitrite).
Is also a desirable mode.

(3) Specific Examples 1-2 As a typical example of a ceramic product to which the present invention is applied, a stoneware tile base material having a water absorption rate of 5% was prepared as follows. That is, 63% by weight of a mixture of raw talc and porcelain stones and 30% by weight of a mixture of feldspar and petalite are mixed and finely ground with a ball mill until a particle size of feldspar becomes about 2 microns or more to obtain a sludge. After mixing 7% of mud clay with this,
Dehydrated and milled to make kneaded clay. Pressing this kneaded clay 300kg / square
Pressurize at cm, and mold into a compact with a packing rate of 0.7 (100 x 100 x 5 mm). This molded body was fired at a maximum temperature of 1150 ° C. for 36 hours to obtain a tile base material having a stoneware quality. The 24-hour immersion water absorption of the tile base was 5%.

In Example 1 (Example), the tile substrate was sealed with an excess amount of 2% ozone water, immersed for 24 hours, and washed with running water. In Example 2 (Comparative Example), the tile base material which was washed with running water without being treated with ozone water was used as it was.

A box-shaped container with an inner frame size of a little over 1m x 1m was placed horizontally, and the mortar for base which consisted of Voltland cement 1 and sea sand 5 was put in a thickness of 5 cm and weight-hardened by weight ratio. .
A mortar for sticking consisting of Portland cement and water was put on it in a thickness of 5 mm, and 10 × 10 pieces of the above tile base sample were stuck on the mortar with a joint interval. In order to accelerate the alkali-silica reaction, the sample was placed at a temperature of 40 ° C,
It was kept for 3 months in an environmental test room with a relative humidity of 95%. In Example 1 according to the present invention, no cracks or stains were visually detected on the surface of the tile substrate and the surface of the joint. In Example 2 which is a comparative example, a circular alkali silica reaction product (water glass) having a diameter of about 0.5 to 2 cm is formed on the surface of the base material and the joint portion.
About 6 to 10 pieces were detected per 1 m x 1 m. The above circular reaction product is one in which the alkali component in the mortar (particularly the ground mortar) penetrates into the tile base material to cause an alkali silica reaction, and the reaction product appears on the surface and the side surface of the tile base material. Is.

(4) Reference Examples 3 to 4 The alkali-silica reactivity of the above stoneware tile base material was tested by the mortar bar method according to JIS A5308 Appendix 8. The tile base was crushed to a particle size specified in the JIS, and Portland cement and water were mixed to prepare a mortar bar specimen. In Example 3, the ground product was sealed in 1.5% ozone water, soaked for 24 hours and washed with water. In Example 4, the untreated ground product was used.

Others were carried out in accordance with the provisions of Annex 8 of JIS A5308. The results are shown in the table below.

That is, it was proved that Example 4 was extremely harmful, and that Example 3 had the alkali-silica reaction sufficiently suppressed.

Action and effect The base-silica reaction (especially alkali-silica reaction) in a ceramic in which a base component and a silica component reactive therewith coexist is extremely harmful to the durability and contamination of the ceramic, but is essentially unsolved. Was in the state of. Although the action of the present invention has not been fully clarified, the glass structure which is the reactive site of the silica component is modified into a hydrous gel-like substance by contacting the reactive ceramics with ozone in the presence of water. , Is thought to achieve an effect whose reactivity is effectively suppressed. For example, a reactive silica component typically has ≡Si-O reactive sites,
In this case, ozone-containing water acts and the long-term stable ≡
It is thought that the Si-OH structure is modified and its reactivity is sufficiently suppressed. However, the present invention is not bound by such a representative theory.

INDUSTRIAL APPLICABILITY The modified ceramic product and the method for suppressing a base reaction according to the present invention are extremely useful for long-term stabilization and prevention of contamination of a reactive silica component-containing ceramic that comes into contact with a base component (particularly an alkali component). Since the ozone-containing water used eventually becomes water, there is no harm or adverse effect.

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Claims (2)

[Claims] 1. A water absorbing ceramic product containing a silicic acid component and / or a silicate component reactive with a basic component is contacted with ozone in the presence of water to modify the reaction site of the reactive silica component. The ceramic product which suppresses the base-silica reaction. 2. A base / silica reaction product that appears on the surface of a ceramic product containing a silicic acid component and / or a silicate component that is reactive with a basic component is removed, and the reaction product of the ceramic product appears. A method for suppressing a base-silica reaction of a ceramic product, which comprises allowing ozone-containing water to penetrate into a portion.