JP6753582B2 - Clay composition - Google Patents

Description

The present invention relates to a clay for pottery, a clay for firing that can be used for the purpose of a glaze for heaping decoration, and a clay composition capable of producing the same by kneading with water or the like.
The present invention also relates to a method for producing a fired product such as ceramics and decorative parts using such clay.

In general, pottery clay is capable of delicate clay work because it contains kaolin-based inorganic clay such as Kibushi clay and Kabume clay, which are excellent plasticizers. However, when this inorganic clay is used as a plasticizer, there is a problem that the transparency is lost after firing and the color becomes turbid (brown or blackish) due to impurities contained in the inorganic clay.
Therefore, pottery clay based on frit (glass powder) and using an organic paste such as carboxymethyl cellulose as a plasticizer instead of inorganic clay is being studied. Since such clay has a frit base, it is baked with a high degree of transparency, and since the organic plasticizer burns out during firing, there is no turbidity. Moreover, even when the main material is an inorganic powder having no plasticity, it has surprising plasticity, and in hand-kneading molding, it has a moldability that exceeds that of wood-knot clay.
However, the clay for pottery using this organic plasticizer has a problem that the firing shrinkage is large. If the firing shrinkage is large, it is difficult to achieve the desired size for firing. In particular, when it is used for swelling decoration on porcelain or the like, if it is widely deployed, the shape before firing cannot be maintained due to shrinkage, and it may crack or crack.

Japanese Unexamined Patent Publication No. 2008-299132

Patent Document 1 describes pulp powder, calcium sulfate, calcium carbonate, and calcium phosphate as work clays that can prevent "dumbness" when dissolved in water, prevent the formation of mold, and prevent deformation due to storage humidity. A mixture of one or more clay substrates selected from the above, carboxymethyl cellulose, sodium polyacrylate, a coloring material, and water is disclosed.
However, the clay disclosed in Patent Document 1 is a work clay used for sculpting or for drawing a three-dimensional picture by pressing it against paper or the like, and is like making fine work by hand. Moreover, it is not supposed to be fired at all.

An object of the present invention is to provide a firing clay which is rich in plasticity so that it can be hand-kneaded and complicated work is performed, and which has a small shrinkage when fired.

As a result of diligent studies to solve the above problems, the present inventors have found three (4) components of calcium sulfate, calcium chloride and / or strontium chloride, and carboxymethyl cellulose (hereinafter, also referred to as "CMC"). The combined and mixed composition can be easily made into a plastic, delicate and easy-to-work clay by adding water and kneading, and in addition to these essential components, the main material (aggregate). It was found that even if various powder materials such as () are added, clay that is easy to work with can be obtained regardless of the type.
Even more surprisingly, clays of this composition were found to have very little shrinkage when fired.

That is, the present invention is as follows.
Calcium sulfate;
A clay composition for firing, which contains calcium chloride and / or strontium chloride; and carboxymethyl cellulose.

According to the present invention, it is possible to easily and easily make a baking clay using all kinds of powders as a main material or without using a main material.
Further, according to the present invention, since it is possible to provide clay for pottery having a small shrinkage when fired, it is possible to easily manufacture a ceramic product (ceramic) having a delicate shape.
Further, according to the present invention, it is possible to provide a special glaze that can be raised and decorated on existing pottery or porcelain.

It is a photograph of the clay work (pasted on the surface of porcelain) produced in Example 19 and Comparative Example 2. It is a photograph of the decorative porcelain produced in Example 19 and Comparative Example 2. It is a photograph in a dark room of the decorative porcelain produced in Example 19 and Comparative Example 2.

Hereinafter, embodiments for carrying out the present invention (hereinafter, referred to as “the present embodiment”) will be described in more detail, but the present invention is not limited to this, and various aspects are not deviated from the gist thereof. It can be transformed.

First, carboxymethyl cellulose (CMC) will be described.
In CMC, a part / all of the hydroxy groups of cellulose are substituted with carboxymethyl groups, and at least a part of the carboxymethyl groups may be in the form of a sodium salt.
By containing CMC, the clay obtained from the clay composition of the present embodiment can be made highly plastic and suitable for delicate work by hand-bending.

The degree of etherification of CMC (degree of substitution of carboxymethyl group per anhydrous glucose unit) is not limited, but if the degree of etherification is too large, it will not easily become clay even if water is added and kneaded, and if it is too small, clay will not be formed. There is a tendency for the stiffness to be insufficient.
Therefore, the degree of etherification of CMC is preferably 0.5 to 1.3, more preferably 0.6 to 1.1, and even more preferably 0.8 to 1.0.

There is no limit to the viscosity of a 1% aqueous solution of CMC (that is, the viscosity of a 1% by mass aqueous solution of CMC measured at 60 rpm using a B-type viscometer at 25 ° C.), but if it is too large, it will be excessive when clay is used. On the contrary, if it is too small, it tends to be insufficient when it is made into clay.
Therefore, it is preferably 400 to 8000 rpm, more preferably 800 to 6000 rpm, and even more preferably 1000 to 5000 rpm.

In the present embodiment, the content of CMC in the clay composition is not limited, but from the viewpoint of ease of work when made into clay, it is preferably 1.0% by mass or more, and 2.0. It is more preferably mass% or more, and further preferably 2.5 mass% or more.
On the other hand, if the CMC content is too high, shrinkage is likely to occur when the clay is fired. Therefore, the content of CMC in the clay composition is preferably 10% by mass or less, more preferably 7.5% by mass or less, and further preferably 5% by mass or less.

Next, calcium chloride and / or strontium chloride will be described.
In the present embodiment, by containing calcium chloride and / or strontium chloride, the hand-bending formability of the obtained clay can be enhanced.
In this embodiment, only one of calcium chloride and strontium chloride may be used, or both may be used.

In the present embodiment, the contents of calcium chloride and strontium chloride in the clay composition are not limited, but from the viewpoint of ease of work (hand-bending formability) when clay is used, calcium chloride and strontium chloride are used. The total of the above is preferably 3% by mass or more, more preferably 5% by mass or more, and further preferably 10% by mass or more with respect to the clay composition.
On the other hand, if it is excessively contained, stickiness becomes conspicuous when it is made into clay and it becomes difficult to use. Therefore, the total amount of calcium chloride and strontium chloride is preferably 25% by mass or less, preferably 20% by mass or less, based on the clay composition. More preferably, it is more preferably 15% by mass or less.

Next, calcium sulfate will be described.
In the present embodiment, a clay rich in plasticity is realized by containing CMC, but CMC is an organic substance, and the clay containing this is liable to shrink when fired. However, according to the research by the present inventors, it has been found that when calcium sulfate is contained in clay containing CMC and calcium chloride and / or strontium chloride, the shrinkage during firing is significantly reduced.
Calcium sulfate also has the effect of causing less discoloration when fired and making the baked color brighter (whiter).

In this embodiment, calcium sulfate may be anhydrous or hydrated. Examples of the hydrate include dihydrate and hemihydrate. Further, gypsum (dihydrate gypsum, hemihydrate gypsum, anhydrous gypsum, etc.) may be used as calcium sulfate.

In the present embodiment, the content of calcium sulfate in the clay composition is not limited, but from the viewpoint of preventing calcination shrinkage, it is preferably 5% by mass or more, and more preferably 10% by mass or more. , 25% by mass or more is more preferable.
Further, from the viewpoint of containing a sufficient amount of other components, it is preferably 70% by mass or less, and more preferably 60% by mass or less.

Further, in the present embodiment, the ratio of the content of calcium sulfate in the clay composition to the content of CMC (calcium sulfate content / CMC content, mass ratio) is preferably 5 or more, and is preferably 10 or more. The above is more preferable.

Next, the main material will be described.
The clay composition of the present embodiment can be made into clay with only the above-mentioned essential three (4) components, but in addition to these, various powder materials can be added as a main material depending on the purpose.
In the present embodiment, the main material is CMC, calcium chloride and / or strontium chloride, which are essential components, and calcium sulfate, and other components contained in the clay composition, such as CMC, and calcium chloride and chloride. The content is higher than any of the total amount of strontium. Such a main material is sometimes called an aggregate.
In the present embodiment, the type of the main material is not limited, and clay that is easy to handle can be obtained regardless of the properties of the powder. In the present embodiment, as the main material, for example, a material generally used as a main material (aggregate) of clay can be widely used. Specific examples include metal oxides such as aluminum oxide, zirconium oxide, silicon oxide (high-purity silica sand), titanium oxide, yttrium oxide, lanthanum oxide, zinc oxide, and magnesium oxide; minerals such as forsterite and cordierite (composite). Oxide); Examples include powder of an inorganic material such as glass powder (glass frit).
One of these may be used alone, or a plurality of types may be used in combination, and desired ones may be appropriately used depending on the purpose of the clay. For example, a ceramic powder such as a metal oxide or a mineral can be used as the main material, and can be appropriately selected according to a desired color, strength, firing temperature, and the like. Further, in the case of making clay for pottery that can be fired at a low temperature, it is preferable to use glass powder as a part of the main material and appropriately adjust the firing temperature.

Further, an additive known as an additive for the pigment of the present embodiment or other clay for firing may be contained, and a liquid such as water (for example, a solvent capable of dissolving CMC) may be contained in advance. ..
In particular, when a so-called phosphorescent material such as a fluorescent material or a phosphorescent material is used as an additive or as a part or all of the main material, it becomes possible to manufacture luminescent ceramics. Specific examples of the phosphorescent material are not limited, and examples thereof include rare earth phosphors containing a rare earth element as an activator in the matrix such as phosphate, silicate, aluminate, and oxide.
However, since such a phosphorescent material loses its phosphorescent performance at a high temperature, it is preferable to set the firing temperature low by using a part of the main material or glass powder as an additive.

The shapes of calcium sulfate, calcium chloride and / or strontium chloride, CMC, and the main material are not limited, but powder is preferable from the viewpoint of ease of handling when made into clay. The particle size is not limited, and can be, for example, 1 to 1000 μm.

The compounding ratio of each component of the clay composition of the present embodiment is not limited, and it is easy to handle as long as it contains the essential three components (that is, calcium sulfate, calcium chloride and / or strontium chloride, and CMC). , Clay with small shrinkage when fired can be obtained.
The blending ratio of the essential components is not limited, but the total content of calcium chloride and strontium chloride should be 1 part by mass or more and the content of calcium sulfate should be 5 parts by mass or more with respect to 1 part by mass of carboxymethyl cellol. However, it is preferable from the viewpoint of ease of clay work and shrinkage of firing.

Clay can be produced by adding a liquid such as water to the clay composition of the present embodiment as needed and kneading (kneading) it. The amount of the liquid added at this time is not limited, and may be appropriately adjusted according to the composition of the clay composition and the type of the liquid so as to have a desired hardness. On the other hand, 5 to 50 parts by mass can be added.
The clay obtained from the clay composition of the present embodiment has excellent plasticity, is rich in stickiness, has good elongation, is soft and is very easy to handle. Therefore, it is suitable for various clay works, and can be formed into delicate, complex and highly decorative shapes such as flowers such as roses and lilies and lace frills by hand.
Moreover, since the clay obtained from the clay composition of the present embodiment has a small shrinkage when fired, it can be made into a ceramic product (ceramic) while maintaining the delicate shape of the clay work. In addition, since the shrinkage during firing is small, it can be firmly adhered to the pottery (porcelain) by pasting it on pottery or porcelain that has been fired or before firing, so that it can be firmly attached to the pottery (porcelain). It can also be used as decorative clay (glaze for heaping decoration).

Next, a method for producing the fired product of the present embodiment will be described.
The manufacturing method of the present embodiment includes a step of molding the above-mentioned clay for firing and a glaze for swelling decoration, and a step of firing the molded product obtained thereby.
When the firing clay is a raised decorative glaze, the firing can be performed after the molded body is attached to the ceramic or porcelain to be decorated. The firing temperature and firing time are not limited, and can be appropriately determined according to the composition of the clay (glaze). For example, when the clay contains a phosphorescent material, the firing temperature should be set low (for example, less than 1000 ° C.) and the firing time should be long (for example, 1 hour to 10 hours) so as not to lose the phosphorescent performance. Is preferable.
According to the manufacturing method of the present embodiment, since clay (glaze for decoration) having a small firing shrinkage rate is used, finely crafted ceramics can be manufactured while maintaining the shape of the molded body.

Next, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these examples.

[Example 1]
The following components were mixed to prepare a clay composition.
(Clay composition combination)
CMC 0.3g
Calcium chloride 0.6g
Strontium chloride 0.6g
Calcium sulfate 1/2 hydrate (hemihydrate gypsum) 3g
Glass powder (main material) 5g
Luminescent powder (main material) 2g

As the CMC, those having the viscosity of the 1% aqueous solution and the degree of etherification shown in Table 1 were used.
The glass powder is Tokan Material Technology Co., Ltd.'s multi-component glass frit for glaze 12-3979, and the phosphorescent powder is Nemoto Lumi Material Co., Ltd.'s BGL-300M (Sr ₄ AL ₁₄ O ₂₅ : Eu). , Dy) was used.

About 2.7 g of water was added to the clay composition obtained as described above, and the clay was kneaded by hand to obtain clay.
This clay was formed into a columnar shape having a length of 150 mm and a cross section of 5 mm in diameter, dried at 110 ° C. for 3 hours, and then the length (length before firing) was measured. Then, it was fired at 400 ° C. for 60 minutes and further at 800 ° C. for 60 minutes, and the length after firing was measured. Then, the firing shrinkage rate was determined from the lengths before and after firing according to the following formula.
Baking shrinkage rate (%) = (length before firing-length after firing) / length before firing x 100

[Examples 2 to 6]
Clay was obtained in the same manner as in Example 1 except that the CMC was changed to that shown in Table 1, and its calcination shrinkage was measured.

[Examples 7 and 8]
Clay was obtained in the same manner as in Example 1 except that the blending amounts of calcium chloride and strontium chloride were changed as shown in Table 1, and the calcination shrinkage ratio was measured.
[Examples 9 to 11]
Clay was obtained in the same manner as in Example 1 except that the type of phosphorescent powder was changed to orange manufactured by Tokyo Intelligent Network Co., Ltd., and its calcination shrinkage was measured.

[Example 12]
Clay was obtained in the same manner as in Example 1 except that the main material was changed from phosphorescent powder to alumina (Al ₂ O ₃ ), and the calcination shrinkage was measured.
[Examples 13 to 18]
Clay was obtained in the same manner as in Example 12 except that the blending amounts of alumina and glass powder were changed as shown in Table 1, and the calcination shrinkage ratio was measured.

[Comparative Example 1]
Clay was obtained in the same manner as in Example 12 except that 3 g of calcium sulfate 1/2 hydrate was not contained and the amount of glass powder blended was increased from 5 g to 8 g instead, and the calcination shrinkage was measured.

Table 1 shows the compositions of the clay compositions of Examples 1 to 18 and Comparative Example 1 and the evaluation of the clay obtained from the clay compositions.

[Example 19]
Three colors of clay were obtained in the same manner as in Example 1 except that yellow, super blue and orange manufactured by Tokyo Intelligent Network Co., Ltd. were used as the phosphorescent pigment. Using these clays and the clays of Example 1 in total of four colors, a clay work of rose flowers (buds), leaves and stems, and florets was prepared by hand. The obtained clay had an excellent balance of plasticity and elasticity, and could be easily worked into the shape of a rose flower (thin, pleated shape) by hand-kneading (Fig. 1A).
Next, when the above clay work was pasted on a separately prepared porcelain (fired) and fired at 400 ° C. for 60 minutes and then at 800 ° C. for 60 minutes, the dimensions and shape hardly changed from before firing. , A beautiful decorative porcelain was obtained (Fig. 2A).
When this decorative porcelain was placed in the dark, it emitted light in four colors (Fig. 3A).

[Comparative Example 2]
The following components were mixed to prepare a four-color clay composition.
(Clay composition combination)
CMC 0.6g
Calcium chloride 0.6g
Glass powder (main material) 5g
Luminescent powder (main material) 2g

As the CMC and the glass powder, the same ones used in Example 1 were used. In addition, as phosphorescent powder, BGL-300M (Sr ₄ AL ₁₄ O ₂₅ : Eu, Dy) of Nemoto Lumi Material Co., Ltd. and four types of yellow, super blue and orange manufactured by Tokyo Intelligent Network Co., Ltd. are used. did.
Using the clay composition obtained as described above, clays of four colors were obtained in the same manner as in Example 1, and clay work was prepared in the same manner as in Example 19. The obtained clay had an excellent balance of plasticity and elasticity as in Example 19, and the same delicate work as in Example 19 was obtained by hand-kneading (FIG. 1B).
Next, when the above clay work was pasted and fired on a separately prepared porcelain (fired) in the same manner as in Example 19, the shrinkage was severely deformed (FIGS. 2B and 3B).

Since the clay made from the clay composition of the present invention has a small shrinkage when fired, it can be preferably used as a clay for pottery or a swelling type decorative glaze.

Claims (6)

Ri degree of etherification from 0.64 to 0.93 der, carboxymethylcellulose 1% aqueous solution viscosity of Ru 3670~7840mPa · s der;
Calcium chloride and / or strontium chloride;
A clay composition for firing, which contains calcium sulfate; and glass powder. The clay composition for firing according to claim 1 , further comprising a fluorescent or phosphorescent material. A glaze composition for swelling decoration comprising the clay composition according to claim 1 or 2 . A clay for firing, which comprises the clay composition according to claim 1 or 2 and water. A glaze for swelling decoration according to claim 3 , which comprises the composition and water for swelling decoration. The step of molding the baking clay according to claim 4 or the raised decorative glaze according to claim 5 , and
A method for producing a fired product, which comprises a step of firing the molded product obtained by the above step.