JP2020117417A - Clay composition for low temperature firing - Google Patents

Abstract

To provide a clay composition for low temperature firing containing obsidian as a solid matter in the amount of 75 to 85 wt.% capable of firing a clay molded product to produce a clay fired product that keeps the shape thereof, and the clay fired product using the clay composition for low temperature firing and a producing method thereof.SOLUTION: The clay composition for low temperature firing contains the obsidian having a particle size of 50 μm or less as a solid matter in the amount of 75 to 85 wt.%. The clay molded product obtained by molding the clay composition for low temperature firing into a desired shape can be fired in a temperature range of 900°C or lower to set. The obsidian may be a finely pulverized product having a particle size of 30 μm or less.SELECTED DRAWING: None

Description

The present invention relates to a clay composition containing obsidian as a main component and a fired clay product. More specifically, the present invention relates to a clay composition containing clay obsidian as a main component and a clay fired product that can be fired at a low temperature of 900° C. or less.

As a raw material for calcined products such as stoneware and pottery, in addition to clay, silica, calionous minerals, feldspar, etc. are generally used. A clay product having plasticity is molded, dried, and then calcined to manufacture a calcined product.

In addition, as a raw material of the baked product, a technique using a material other than clay has been developed. For example, a baked product using incinerated ash (Patent Document 1), and a baking product containing an organic material such as dried okara A product is known (Patent Document 2).

Here, in the case of producing the baked product, it is common to carry out baking at a temperature higher than 1000°C. For example, the kiln is a kiln, and the firing temperature is 1200 to 1300°C. The pottery is made of clay containing a large amount of kaolinite (kaolin) and montmorillonite, is fired at a temperature of 1100 to 1300° C. in a kiln, and a glaze is used.

On the other hand, obsidian is a natural glass, but it is known that when it is heated to a high temperature, the water contained in it will foam and become pumice by being vaporized or gasified (so-called perlite). .. Since the obsidian pearlite particles have large cavities, and the air contained in the cavities is used as a raw material for the heat insulating material (Patent Document 3), or when contacted with water, water is absorbed to form water. It is also used as a soil conditioner because it has the ability to retain soil.
However, when clay that contains a large amount of unexpanded obsidian that has not become pearlite particles is fired at a high temperature (1000°C or higher) as with fired products such as stoneware and pottery, obsidian during the firing Foaming causes the shape of the fired product to change, the strength is lost and disjointed, and even if a fired product is obtained, the strength is not sufficient and it easily cracks. A fired product using clay containing a large amount of obsidian has not been heretofore known, because water leaks when filled with water even if it can be retained.

JP-A-11-21164 JP-A-7-206509 JP, 2012-36020, A

Therefore, in view of the above circumstances, the present invention is a clay for low temperature firing capable of firing a clay fired product in which the shape of the clay molded product is retained while containing obsidian in a solid content of 75 to 85% by weight. An object of the present invention is to provide a composition, a clay-fired article using the clay composition for low-temperature firing, and a method for producing the same.

In order to solve the above-mentioned problems, the inventors of the present invention have made various investigations, and have produced obsidian whose particle size is adjusted to 50 μm or less, and contain a large amount of this fine obsidian (75 to 85% by weight as solid content). When the clay composition was fired at a temperature as low as 900° C. or less, an obsidian did not foam during firing, and since the particle size was minute, a fired product in which the shape of the clay molded product was retained was obtained. The inventors have completed the present invention by finding that this fired product has strength and that water does not leak even when the recesses provided on the surface of the fired product are filled with water.

That is, the gist of the present invention is
[1] A clay composition for low-temperature calcination, characterized by containing 75 to 85% by weight of solid particles of obsidian having a particle size of 50 μm or less,
[2] The clay composition for low temperature firing as described in [1] above, wherein the obsidian is a finely pulverized product having a particle size of 30 μm or less,
[3] The clay composition for low-temperature calcination according to [1] or [2], which can be solidified by calcining in a temperature range of 900° C. or lower.
[4] A clay molded article formed into a desired shape by using the clay composition for low temperature firing according to any one of the above [1] to [3] is fired in a temperature range of 900° C. or lower to be solidified. Characteristic, manufacturing method of clay baked product,
[5] A clay-fired product, characterized by containing granular obsidian having a particle size of 50 μm or less as a solid content of 75 to 85% by weight,
[6] The clay fired product according to [5], wherein the obsidian is a finely pulverized product having a particle size of 30 μm or less.

Clay fired products obtained from the clay composition for low temperature firing of the present invention has strength, and since water does not leak even when water is filled in the recesses provided on the surface, tableware, containers such as vases, and the like, It can be suitably used as a craft or ornament having a desired shape.
Further, since the clay composition for low temperature firing of the present invention can be fired at a lower temperature than the conventional method, the production cost can be reduced.

The clay composition for low temperature firing of the present invention is characterized by containing granular obsidian having a particle size of 50 μm or less in a solid content of 75 to 85% by weight.

The obsidian used in the present invention is a granular material having a particle size of 50 μm or less.
The particle size of 50 μm or less means that the maximum particle size is 50 μm or less.
Further, the granular shape may be a granular shape that falls within the granularity, and includes, for example, a substantially spherical shape, a substantially elliptic spherical shape, a substantially triangular pyramid shape, a substantially cylindrical shape, and a polyhedral shape, but is not particularly limited.
Further, the obsidian is preferably a finely pulverized product having a particle size of 30 μm or less from the viewpoint that the moldability with clay is improved and the strength of the clay fired product is maintained.
The above-described granular obsidian can be obtained, for example, by subjecting obsidian having a large particle size to a pulverizer and further finely pulverizing it.
The type of the crusher is not particularly limited as long as it can crush the obsidian to a particle size of 50 μm or less.
Further, the crushed obsidian may be passed through a sieve having a desired mesh size to separate obsidian particles having a particle size of 50 μm or less from particles having a particle size of more than 50 μm.

The solid content of the obsidian in the clay composition for low temperature firing of the present invention is 75 to 85% by weight, and is characterized in that obsidian is a main component which is difficult to use as a raw material for conventional fired products. ..
When the solid content of the obsidian exceeds 85% by weight, obsidian particles may be dropped from the clay fired product or the formability of the clay fired product may be deteriorated.

In the clay composition for low temperature firing of the present invention, clay is mentioned as a component other than the obsidian.
The clay may be any clay that contains clay mineral as a main component and is a raw material for ceramics. For example, frog-eyed clay, kibushi clay, kaolin clay and the like can be exemplified, but unglazed clay is preferable from the viewpoint that firing at a low temperature can be performed particularly well.
The clay may be mixed with glassy minerals such as mica and feldspar, fine aggregate, and the like, if necessary.

The solid content of the clay in the clay composition for low temperature firing of the present invention is 15 to 25% by weight.
When the solid content of the clay is lower than 15% by weight, obsidian particles may be dropped from the fired clay product or the formability of the fired clay product may be deteriorated. Further, when the solid content of the clay exceeds 25% by weight, it is difficult to exert the effect derived from obsidian, which is not preferable.

Further, the amount of water mixed in the clay composition for low temperature firing of the present invention may be appropriately adjusted according to the molding method used. For example, in the molding method used, water may be added to such an extent that the clay composition for low-temperature calcination of the present invention can be plasticized to have a desired shape so that the clay composition for low-temperature calcination of the present invention can have plasticity.

The clay composition for low temperature firing of the present invention can be produced by mixing the obsidian and the clay. The mixing method is not particularly limited, and a known method using a hand or a stirrer can be used. Further, the plasticity of the clay composition may be adjusted while adding and mixing water according to the molding method used.

The clay composition for low temperature firing of the present invention is molded into a desired shape to obtain a clay molded product, and the clay molded product is then fired in a temperature range of 900° C. or lower to be solidified to obtain a clay fired product. be able to.

In the present invention, molding refers to processing the clay composition for low temperature firing of the present invention into a desired shape, and the clay molded product is in a state having plasticity peculiar to the clay composition.
In the present invention, firing means heating the clay molded product at 900° C. or lower.
In the present invention, the term "solidified" means that the clay-fired product is a solid product that has lost the plasticity peculiar to the clay composition.

Examples of the molding method include a method of forming a desired shape by hand and a method of using a lathe.
The molding method may be an industrial method such as a wet molding method such as an extrusion molding method, a wet press molding method, or a casting molding method.
In the case of extrusion molding, if necessary, a plasticizer is further added to the clay composition for low temperature firing of the present invention so that the water content is 5% by weight or more and 40% by weight or less, more preferably 10% by weight or more and 25% by weight or less. Adjust and shape. A plate-shaped green body is obtained by extrusion-molding the clay composition for low-temperature firing of the present invention, spreading it into a flat plate, and rolling it with a rolling roller.

The shape of the clay molded product obtained as described above is not particularly limited, and various shapes such as a container shape, a spherical shape, and a plate shape can be mentioned.

In the present invention, the firing temperature is adjusted to 900° C. or lower.
In the present invention, when the firing temperature exceeds 900° C., obsidian, which is contained in a large amount in the clay molded product, foams, and the strength of the clay baked product may be reduced, or the clay may be broken and lose its shape. There is a nature.
The firing temperature is preferably 350° C. or higher and 850° C. or lower from the viewpoint of efficiently crystallizing water by evaporating water of crystallization. Further, the temperature may be changed so as to increase stepwise or with time during firing, or may be increased or decreased.
The general firing temperature of ceramics is 1000° C. or higher, but compared to such a high temperature, the clay composition for low temperature firing of the present invention has an advantage of low manufacturing cost.

The firing time may be appropriately set according to the shape and thickness of the clay molded product and the firing temperature, and is not particularly limited. For example, if it is around 900°C, the water of crystallization can be solidified by evaporation even if it is fired for a short time, and if it is around 350°C, it can be fired for a long time of more than ten hours to solidify the clay-fired product. can do.

Further, a glaze may be attached to the surface of the clay-fired product obtained as described above, and the product may be fired again.
There is no particular limitation on the glaze as long as it is used for ceramics.
The firing temperature after applying the glaze may be adjusted to a temperature range of 900° C. or lower.

The clay-fired product obtained as described above can be suitably used as a container or an ornament such as a stoneware and a pottery.
Further, in the clay-fired product of the present invention, since the solid content of obsidian is 75 to 85% by weight, the action and effect derived from obsidian can be exhibited.
For example, it is known that water in which obsidian is soaked has a bioactive effect (Kanagawa University Annual Report '98, 155, 1999-03). Can be improved. Specifically, in the case of a container-shaped clay-fired product, water with improved physiological activity can be obtained by filling the container with water.
In addition, by submerging the clay-fired product in a place filled with water such as an aquarium, vase, or bath, the physiologically active action of the filled water can be improved.
In addition, clay clay products are spread over the surface of soil such as fields, flower beds, and pots where plants such as flowers and vegetables are planted, or clay clay products are buried in the soil to modify these soils. be able to.

(Example 1)
Commercially available obsidian was supplied to a crusher having a particle size adjusting function to prepare particles having a particle size of 50 μm or less.
Next, 80 parts by weight of the obtained obsidian having a particle size of 50 μm or less and 20 parts by weight of clay for unglazed clay are provided to a mixing device, water is added while stirring and mixing, and plasticity is adjusted to such an extent that they can be kneaded by hand. The low temperature firing clay composition (obsidian solid content 80% by weight) was prepared.

Next, a clay molded article formed into a vessel shape (thickness of about 3 mm) was kneaded by hand with the clay composition for low temperature firing, and was fired in a temperature range of 400 to 850° C. for 8 hours in a firing machine for firing.
The obtained clay-fired product had sufficient strength as a container. Moreover, no water leaked when the clay-fired container was filled with water.

(Example 2)
Clay composition (solid content of obsidian: 75% by weight, 85% by weight: 85% by weight) %) was prepared, and a clay molded product formed from these clay compositions in a vessel shape was calcined and solidified to obtain a clay calcined product.
All of the obtained clay-fired products had sufficient strength as a container, as in Example 1. Moreover, no water leaked when the clay-fired container was filled with water.

(Example 3)
A glaze for ceramics was applied to the outer surface of the pot-shaped clay fired product obtained in Example 1 and fired at a temperature of 400 to 800°C.
The clay-fired product obtained by applying the glaze had sufficient strength as a container, as in Example 1, and there was no water leakage when the clay-fired product container was filled with water. In addition, the portion coated with the glaze had improved strength, the appearance was transparent, and the appearance was like ceramics.

(Example 4)
A clay composition (solid content of obsidian: 80% by weight) was prepared in the same manner as in Example 1 except that obsidian having a particle size of 50 μm or less was further pulverized to a particle size of 25 μm or less. The clay molded product formed into a shape was fired and solidified to obtain a clay fired product.
The obtained clay-fired product had sufficient strength as a container, as in the case of Example 1. Moreover, no water leaked when the clay-fired container was filled with water.
Further, the surface of the container had a more delicate touch than that of Example 1.

(Comparative Example 1)
A clay composition (obsidian solid content 90% by weight) was prepared in the same manner as in Example 1 except that the amount of finely divided obsidian having a particle size of 50 μm or less was 90 parts by weight and the amount of clay was 10 parts by weight. However, this clay composition lacked clay, and it was difficult to produce a clay molded product in a desired shape.
Moreover, even when fired, the strength of the obtained fired clay product was insufficient and the product was immediately cracked.

(Comparative example 2)
Firing was performed in the same manner as in Example 1 except that the firing temperature was 1000°C. However, the desired shape could not be maintained, resulting in a clay fired product that was broken into pieces.

Claims (6)

A clay composition for low-temperature calcination, characterized by containing granular obsidian having a particle size of 50 μm or less as a solid content of 75 to 85% by weight. The clay composition for low temperature firing according to claim 1, wherein the obsidian is a finely pulverized product having a particle size of 30 μm or less. The clay composition for low temperature calcination according to claim 1 or 2, which can be solidified by calcining in a temperature range of 900°C or lower. Clay calcination, characterized in that a clay molded product formed into a desired shape by using the clay composition for low temperature calcination according to any one of claims 1 to 3 is calcinated in a temperature range of 900°C or lower to be solidified. Method of manufacturing goods. A clay-fired product, characterized by containing granular obsidian having a particle size of 50 µm or less as a solid content of 75 to 85% by weight. The clay burned product according to claim 5, wherein the obsidian is a finely pulverized product having a particle size of 30 µm or less.