JP2002255673A - Ceramic product having color rendering property and colorant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a color rendering ceramic product which is constituted so as to easily exhibit color rendering property in a low cost, and a colorant. SOLUTION: A first color rendering ceramic product is produced by forming a ceramic raw material containing fine particles of at least one oxide of a rare earth element selected from holmium, praseodymium, neodymium, and erbium into a prescribed form and then firing the formed body. A second color rendering ceramic product is produced by coating the surface of a ceramic raw material formed into a prescribed form with a colorant containing fine particles of at least one oxide of a rare earth element selected from holmium, praseodymium, neodymium, and erbium and then firing the coated raw material. The preferable average particle diameter of the fine particles of the oxide of the rare earth element mentioned above is in the range of 0.01 to 20 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic tableware, which is configured so that the atmosphere can be changed between day and night, a ceramic accessory that changes color by a light source, and a color rendering ceramic product such as fancy goods. And a coloring material for coloring the ceramic product. More specifically, the present invention relates to a color rendering ceramic product and a coloring material which are configured to be changed into different color tones by irradiating various external light sources such as sunlight, a fluorescent lamp and an incandescent lamp.

[0002]

2. Description of the Related Art Conventionally, as a color rendering ceramic product of this kind, there has been known, for example, a porcelain decorated by the method of using neodymium for a porcelain pigment disclosed in Japanese Patent Application Laid-Open No. 63-159247. I have. This ceramic is
Neodymium oxide and aluminum oxide are mixed and fired at a predetermined temperature to synthesize Nd ₂ O ₂ · Al ₂ O ₃ , which is finely pulverized, or as a pigment for underlaying, or coloring of a color glaze It is manufactured by utilizing as a pigment for use.
And, since the ceramics can be colored without deteriorating the unique light absorption characteristics of neodymium, dichroism, a property of changing the color tone between natural light and artificial light, is exhibited.

[0003] Japanese Patent Application Laid-Open No. 9-227253 discloses a method of manufacturing a ceramic paint. In this method, silica is contained in an amount of 30.0 to 45.0% by weight and lead oxide 4
5.0 to 60.0% by weight, and the total amount of silica and lead oxide is 85.0 to 90.0% by weight, and in addition, alumina is 0.5 to 4.0% by weight. And boron oxide at 1.0 to 4.0% by weight and calcium oxide at 0.1%.
It contains 5 to 4.0% by weight, 1.0 to 3.0% by weight of lithium oxide, and 1.0 to 3.5% by weight of zirconium oxide so that the total amount is 100% by weight. The glass composition is prepared in an oxidizing atmosphere at 1,000 to 1,40
After heating to a temperature of 0 ° C. for rapid melting and aging, the melt is quenched and the resulting solid is pulverized. Further, as the coloring agent, one or two or more selected from the group consisting of cerium oxide, praseodymium oxide, neodymium oxide and erbium oxide in an amount of 1.0 to 15.0 parts based on 100 parts of the glass composition. Colored rare earth element oxides can be used.

[0004]

However, the conventional method of using neodymium for ceramic pigments requires a step of pulverizing neodymium oxide and aluminum oxide once firing at a high temperature. Similarly, in the above-mentioned conventional method for producing a paint for ceramics, a step of pulverizing the glass composition after rapid melting and aging is required. For this reason, there is a high possibility that impurities will be mixed during the pulverization, and various steps such as baking and pulverization must be performed. Had been

The present invention has been made by focusing on the problems existing in the prior art as described above. It is an object of the present invention to provide a color rendering ceramic product and a coloring material which are configured to exhibit color rendering properties easily and inexpensively.

[0006]

In order to achieve the above object, a color rendering ceramic product according to the present invention is characterized in that at least one rare earth element oxide selected from holmium, praseodymium, neodymium and erbium is used. It is manufactured by firing a ceramic raw material containing fine particles of the above-mentioned shape after forming it into a predetermined shape, and the color is reversibly changed according to the type of the external light source.

According to a second aspect of the present invention, there is provided the color rendering ceramic product, wherein at least one rare earth element oxide selected from holmium, praseodymium, neodymium and erbium is formed on the surface of the ceramic molded body or fired body formed in a predetermined shape. It is manufactured by applying a colorant containing fine particles of a product and then baking, and reversibly changes color according to the type of external light source.

[0008] The color rendering ceramic product according to the third aspect of the present invention is the color rendering ceramic product according to the first or second aspect,
The average particle diameter of the fine particles of the rare earth element oxide is 0.01
-20 μm.

The colorant of the invention according to claim 4 is a colorant used for producing the color rendering ceramic product according to claim 2, wherein the colorant is at least one selected from holmium, praseodymium, neodymium and erbium. It contains fine particles of one kind of rare earth element oxide, and reversibly changes its color according to the type of external light source.

[0010]

Embodiments of the present invention will be described below in detail. The first color rendering ceramic product of the present embodiment is manufactured by adding fine particles of a rare earth element oxide to a ceramic raw material, forming the fine particles into a predetermined shape, and then firing. Further, the second color rendering ceramic product of the present embodiment contains the fine particles of the rare earth element oxide after forming the ceramic raw material not containing the fine particles of the rare earth element oxide into a ceramic molded body or fired body having a predetermined shape. It is manufactured by coloring and firing the surface of the ceramic molded body or fired body with a coloring material.

The ceramic raw material is composed of a natural raw material or an artificially made inorganic solid material.
Feldspar, clay, glass and the like. In addition, the firing temperature may be a firing temperature for firing a normal ceramic product, and is preferably in the range of 500 to 1650 ° C, more preferably 700 to 1350 ° C. These first
And the second color rendering ceramic products include, for example, ceramics (porcelain, porcelain, stoneware, bone china, etc.), fine ceramics (zircon, mullite, etc.), glass (soda-lime glass, borosilicate glass, borosilicate glass, aluminosilicate glass, quartz) It is used in various forms such as glass, enamel, cloisonne, and rakuyaki. The ceramics and fine ceramics are mainly baked at a temperature of 1000 ° C. or more, and the ceramic overpainting, glass, enamel, cloisonne and rakuyaki are mainly baked at a temperature of less than 1000 ° C.

The rare earth element oxide is contained for coloring the first and second ceramic products to impart color rendering properties. The color rendering property refers to the property of showing different phenomena of how colors look when illuminating an object with a light source having a different spectral distribution, for example, sunlight, a fluorescent lamp, an external light source of a different type such as an incandescent lamp. When illuminated, it has the property of changing to a unique color tone depending on the type of the light source. Further, the color of the rare earth element oxide is changed instantaneously and reversibly in accordance with the type of the external light source.

As the rare earth element oxide, holmium (Ho), praseodymium (Pr), neodymium (Nd)
Or an oxide of erbium (Er), that is, holmium oxide (Ho ₂ O ₃ ), praseodymium oxide (Pr ₂ O ₃ ), neodymium oxide (Nd ₂ O ₃ ), or erbium oxide (Er)
₂ O ₃ ) is used. Alternatively, at least one selected from holmium, praseodymium, neodymium and erbium
Fine particles of various rare earth element oxides may be appropriately mixed and used. Further, as the rare earth element oxide, holmium oxide is most preferably used because the color rendering properties are most remarkably exhibited.

The average particle diameter of the fine particles of the rare earth element oxide is preferably 0.01 to 20 μm, more preferably larger than 0.1 μm and 20 μm or less, and still more preferably larger than 0.1 μm and 9 μm or less. Is within. If the average particle size of the fine particles of the rare earth element oxide is less than 0.01 μm, it becomes extremely difficult to disperse the fine particles in the first color rendering ceramic product. Also,
It is also very difficult to prepare rare earth oxide fine particles with an average particle size of less than 0.01 μm. On the other hand, when the average particle diameter exceeds 20 μm, the change in color tone according to the type of the external light source is small, and sufficient color rendering properties cannot be exhibited. Further, the purity of the rare earth element oxide contained in the first and second color rendering ceramic products is preferably 95 to 100%, and more preferably 99 to 100%, in order to exhibit high color rendering. Is more preferred.

The content of the rare earth element oxide added to the ceramic raw material when producing the first color rendering ceramic product is preferably 5 to 30% by weight, more preferably 5 to 20% by weight. is there. If the content of the rare earth element oxide in the ceramic raw material is less than 5% by weight, the ceramic product cannot exhibit sufficient color rendering properties. On the other hand, when it exceeds 30% by weight, it becomes difficult to produce a ceramic product by firing.

The coloring material of the present embodiment includes the holmium,
It contains fine particles of at least one rare earth element oxide selected from praseodymium, neodymium and erbium. Examples of a method for coloring the second color rendering ceramic product using the coloring material include a coloring glaze, an underpainting method, an overpainting method, and an inglazing method.

In the method using a colored glaze, a ceramic material is formed into a predetermined shape and then fired once at a firing temperature of about 800 to 1300 ° C., and a metal oxide or an inorganic pigment is added to an uncolored glaze (basic glaze). This is a method in which a ceramic product is colored by glazing with the added glaze (colored glaze) and firing again at about 1000 to 1350 ° C. The important features of the colored glaze and the metal oxides and inorganic pigments added to the glaze are that they are melted by firing to coat a ceramic product, that they have excellent coloring properties, and that they are colored by the firing temperature. Is difficult to change, the same color is formed regardless of the type of the base glaze, and the color mixing can be performed by adding a plurality of inorganic pigments at the same time. Generally, metal oxides are easily dissolved or decomposed in a base glaze at a high temperature, and thus the color of the metal oxide itself tends to be lost. For this reason, inorganic pigments composed of composite oxides are very often used for firing at high temperatures. In addition, the rare earth element oxide has the property of sufficiently covering the disadvantages of the general metal oxide.

In the underpainting method, a ceramic raw material formed in a predetermined shape is calcined at a low temperature of about 800 to 1000 ° C., and then the surface is painted and glazed.
This is a method of decorating a ceramic product by firing at a high temperature of １３1350 ° C. That is, in this method,
The surface of the calcined ceramic material is decorated by applying a coloring material (undercolor) dissolved or dispersed in water or a predetermined solvent. In this coloring material (undercolor), the content of the rare earth element oxide excluding the weight of water or the solvent is preferably 30 to 100% by weight, more preferably 50 to 100% by weight. When the content of the rare earth element oxide in the coloring material is less than 30% by weight, the amount of the rare earth element oxide in the coloring material decreases, so that the color unique to the rare earth element oxide can be visually observed. It may not be possible.

In the overpainting method and the inglazing method, a ceramic raw material having a glass layer or a glaze layer on the outer surface is fired once at a temperature of about 500 to 1350 ° C. This is a method of decorating a ceramic product by firing at a temperature of about 1200 ° C. As a coloring material (overpaint) used in the overpainting method, a Western paint in which the rare-earth element oxide and glass called a frit raw material are mixed because a pigment is not easily dissolved and a color is easily formed. Is most preferably used. The content of the rare earth element oxide in the frit is preferably 5 to 30% by weight, more preferably 5 to 20% by weight. If the content of the rare earth element oxide in the frit is less than 5% by weight, sufficient color rendering properties cannot be exhibited. On the other hand, if it exceeds 30% by weight, the frit may not be completely dissolved. In addition, in order to reduce the influence on a human body, it is preferable that lead is not contained in the frit.

Therefore, in the first color rendering ceramic product of the above embodiment, a ceramic material containing fine particles of at least one rare earth element oxide selected from holmium, praseodymium, neodymium and erbium is formed into a predetermined shape. It is manufactured by baking later. In addition, the second color rendering ceramic product of the present embodiment has a surface of a ceramic formed body or a fired body formed in a predetermined shape, and at least one rare earth element oxide selected from holmium, praseodymium, neodymium, and erbium. It is manufactured by applying a coloring material containing fine particles and then firing. Further, the coloring material of the present embodiment contains fine particles of at least one rare earth element oxide selected from holmium, praseodymium, neodymium, and erbium. For this reason, the optical characteristics of the rare earth element oxide are exhibited, and the color rendering properties can be extremely easily and inexpensively exhibited according to the type of the external light source. Therefore, it can be easily and inexpensively used for various high-value-added applications such as a tableware that can change the atmosphere between day and night, accessories that change color by a light source, and fancy goods.

On the other hand, for example, in JP-A-11-246219, photochromic ultrafine particles comprising an oxide of any of Ho, Nd and Pr and having an average particle diameter in the range of 5 to 100 nm, and a method for producing the same are disclosed. Is disclosed.
Since the photochromic ultrafine particles are configured to be contained in an organic substance such as a synthetic resin product or a synthetic fiber which is not intended to be fired at a high temperature (500 ° C. or more), the ultrafine particles at the time of the raw material are used. The color and optical characteristics of the fine particles can be easily and sufficiently maintained even after production (after molding). However, the oxide has a transition temperature between about 550-1000 ° C.
At higher temperatures, the photochromic effect is significantly reduced. In contrast, in general, in ceramic products, 500
Since the sintering process at a high temperature of at least ℃ is required for production, it is extremely rare that the color and optical characteristics of the raw material are kept as they are even after sintering. As a result of earnest study, the above-mentioned rare earth element oxides were adopted. In particular, in the present embodiment, due to the coexistence with silicon oxide which is a main component of the ceramic, a part of the added rare earth element oxide is stabilized as silicate, and the photochromic effect is 500 ° C or more. It has been found that it can be sufficiently maintained even at high temperatures. Also, the conventional method for producing photochromic ultrafine particles requires an extremely complicated and many steps as compared with the present embodiment. Furthermore, since these color rendering ceramic products have high weather resistance, light resistance and chemical resistance, there is almost no chemical change due to acid due to vinegar or alkali due to detergent, and almost no discoloration due to long-term use. These properties are even better than synthetic resin products and synthetic fibers containing the conventional photochromic ultrafine particles.

[0022]

EXAMPLES Examples of the above embodiment will be described below. (Example 1) As a base glaze, 48% by weight of Indian feldspar,
Ca-containing 12% by weight of limestone, 8% by weight of zinc white, 8% by weight of New Zealand kaolin and 24% by weight of silica stone
A Zn base glaze (transparent glaze) was prepared. Subsequently, holmium oxide fine particles having an average particle diameter of 30 nm (manufactured by C-I-Kasei Co., Ltd.) were added to the Ca-Zn base glaze so that the holmium oxide content was 5, 10, 15, 20, and 30% by weight.
5 different Ca-Zn glaze formulations were prepared. An appropriate amount of water was added to each of these preparations, and they were mixed well using a porcelain mortar to prepare a glaze slurry. Next, 900
The above glaze slurry is applied to the surface of the porcelain tile preliminarily baked at a temperature of 0 ° C., dried, and then fired in an oxidizing atmosphere at 1250 ° C. for 12 hours, followed by firing at a temperature of 1 hour, thereby obtaining a color rendering property. A ceramic tile was manufactured.

(Example 2) As a base glaze, a Ca-Ba base glaze (transparent transparent) containing 48% by weight of Indian feldspar, 12% by weight of limestone, 8% by weight of barium carbonate, 8% by weight of New Zealand kaolin and 24% by weight of silica stone was used. A color rendering ceramic tile was manufactured in the same manner as in Example 1 except that glaze was used.

Example 3 A Ca base glaze (transparent glaze) containing 52% by weight of Indian feldspar, 13% by weight of limestone, 9% by weight of New Zealand kaolin and 26% by weight of quartzite was used as the base glaze. A color rendering ceramic tile was manufactured in the same manner as in Example 1.

(Example 4) As base glaze, 48% by weight of Indian feldspar, 12% by weight of limestone, 8 strontium carbonate
Wt%, New Zealand kaolin 8 wt% and quartzite 2
Ca-Sr base glaze containing 4% by weight (transparent glaze)
A color rendering ceramic tile was manufactured in the same manner as in Example 1 except that was used.

Example 5 As base glaze, 50% by weight of Indian feldspar, 12.5% by weight of limestone, calcined talc 4.2
A color rendering ceramic tile was manufactured in the same manner as in Example 1 except that a Ca—Mg base glaze (transparent glaze) containing 8.3% by weight of New Zealand kaolin and 25% by weight of silica stone was used.

<Color Rendering Test 1> In all the color rendering ceramic tiles of Examples 1 to 5, glazes having a holmium oxide content of 20% by weight or less were completely melted to obtain a glossy surface. However, with 30% by weight of the glaze, the wettability between the tile and the glaze deteriorated, and the glaze was scattered in a scaly state. Therefore, the content of each glaze is 2
For a tile sample of 0% by weight or less, D64 light source (sunlight measurement light source), F10 light source (fluorescent lamp measurement light source: three-wavelength daylight white), and A light source using a Minolta spectrophotometer CM-3600d. (Measuring light source for incandescent light bulbs) Color measurement was performed using three different light sources. FIG. 1A shows a part of the results. In the drawings, ● represents D65.
A light source, ■ indicates an F10 light source, and ◇ indicates a colorimetric result when irradiated with an A light source.

As a result, the L ^* values of the D65 light source and the A light source,
Both the a ^* value and the b ^* value were relatively close values. On the other hand, in the case of F10 light source, D65 light source and A
As compared with the light source, the L ^* value and the b ^* value were small, and the a ^* value was large. Furthermore, as the content of holmium oxide increases, D
The L ^* value of the 65 light source and the A light source and the a ^* value of the F10 light source increased, and the b ^* value of the F10 light source decreased. Here, the L ^* value indicates the lightness of the color, and the a ^* value and the b ^* value indicate the chromaticity. In other words, changes in the a ^* value and b ^* value affect the color change, and the higher the change rate, the higher the color rendering properties. Content of holmium oxide fine particles is 10% by weight
Above, the F10 light source and the D65 light source (A light source)
^{The *} value and the b ^* value were significantly different, and it was found that the color changed depending on the light source.

Next, using the colorimetric results of the a ^* value and the b ^* value when the holmium oxide content was 15% by weight, a graph showing the characteristics depending on the light source was prepared. These results are shown in FIG. In FIG. 2, the horizontal axis represents the a ^* value, and the vertical axis represents the b ^* value. Also, in FIG. 2, the colorimetric results of the D65 light source of the Ca—Zn glaze of Example 1
The colorimetric results of the F10 light source are plotted with △, and the colorimetric results of the A light source are plotted with △, and D6 of the Ca—Ba glaze of Example 2 is plotted.
● The colorimetric result of 5 light sources is ●, the colorimetric result of F10 light source is 、, A
The colorimetric results of the light source were plotted with semi-black filled circles. Similarly, the color measurement result of the D65 light source of the Ca glaze of Example 3 is Δ,
The colorimetric results of the F10 light source are plotted with □, and the colorimetric results of the A light source are plotted with semi-black □, and the Ca—Sr glaze of Example 4 is D6.
The colorimetric results of 5 light sources are ▼, the colorimetric results of F10 light source are Δ, A
The colorimetric result of the light source was plotted with a semi-black solid square, and
色, F10
The color measurement result of the light source is indicated by ◇, and the color measurement result of A light source is
Plotted.

As a result, it was found that the a ^* value and the b ^* value at the same light source were substantially at the same position, and that the D65 light source and the A light source were also close to each other. Here, when the chromaticity is examined from the a ^* value and the b ^* value, the D65 light source and the A light source show yellow, and F10
It was found that the light source showed a pink color. In fact, the sample showed a yellow color under sunlight and incandescent lamps,
It showed a pink color under the fluorescent light of the wavelength.

Example 6 Silicon oxide (SiO ₂ ) 3
9.1 wt%, aluminum oxide (Al ₂ O ₃ ) 7.9 wt%, calcium carbonate (CaCO ₃ ) 8.5 wt%, magnesium carbonate (MgCO ₃ ) 2.4 wt%, zinc oxide (ZnO) 0 0.7% by weight, potassium carbonate (K ₂ CO ₃ )
1.3% by weight, sodium carbonate (Na ₂ CO ₃ ) 10.2
% By weight and 29.9% by weight of boric acid (H ₃ BO ₃ ) were weighed and mixed, melted at 1200 ° C., quenched and pulverized,
Further, a lead-free frit (lead-free frit) raw material was prepared by passing through a 60-mesh sieve. By adding holmium oxide fine particles having an average particle diameter of 30 nm to this lead-free frit raw material, the content of holmium oxide is reduced to 5, 1,
Four different formulations were prepared at 0, 20 and 30% by weight.

To each of these preparations, an appropriate amount of water and 1% by weight of carboxymethyl cellulose (CMC) were added and mixed well using a porcelain mortar to prepare a glaze slurry for low fire degree. The low-fire glaze melts at a firing temperature of 700 to 900 ° C. and is generally used as an upper paint (Western paint). Next, after applying and drying each glaze slurry on the surface of the hard tile prepared in advance by baking, the temperature was raised in an oxidizing atmosphere at 800 ° C. for 7 hours.
By firing for 1 hour, a color rendering ceramic tile was manufactured. In these color rendering ceramic tiles, the glaze portion of the tile having a holmium oxide fine particle content of 20% by weight or less was completely melted, and a glossy glass layer was obtained, but 30% by weight was added. The glaze part of the tile was not glossy because it was not completely melted. Next, each of the color rendering ceramic tiles of Example 6 was subjected to color measurement using a Minolta spectrophotometer CM-3600d with three types of light sources of D65 light source, F10 light source, and A light source. The results are shown in FIG. In FIG. 1 (b), ● represents the colorimetric results when illuminating the D65 light source, ■ represents the F10 light source, and ◇ represents the A light source.

As a result, the L ^* value was reduced when the holmium oxide content was 10% by weight or more in any light source. The a ^* value increases as the content of holmium oxide increases.
The five light sources and the A light source were small, and the F10 light source was large, and the difference widened. On the other hand, the b ^* value did not change much when the content of holmium oxide was 10% by weight or more. From these results, it was found that, as the content of holmium oxide was increased, the change in chromaticity due to the difference in the light source was large, and the color rendering was enhanced. In fact, the sample showed yellow under sunlight or incandescent lamps and pink under three-wavelength fluorescent lamps.

(Example 7) The lead-free frit raw material prepared in Example 6 was weighed and mixed with holmium oxide fine particles having an average particle diameter of 30 nm and an afterglow phosphor to prepare two kinds of preparations. . In addition, one of the two types of formulations contains 10% by weight of holmium oxide and 10% by weight of a blue-green afterglow phosphor (manufactured by Nichia Corporation).
The other formulation contains 10% by weight of holmium oxide and 10% by weight of a red afterglow phosphor (Nichia Corporation). To each of these formulations was added an appropriate amount of water and 1% by weight of C
MC and the mixture were mixed thoroughly using a porcelain mortar to prepare a low-fire glaze slurry. In addition, the low fire glaze is
It melts at a firing temperature of 700 to 900 ° C, and is generally used as an upper paint (Western paint). Next, after applying and drying each glaze slurry on the surface of the hard tile prepared in advance by baking, the baking is performed by heating at 800 ° C. in an oxidizing atmosphere for 7 hours and holding for 1 hour. Manufactured color rendering ceramic tiles. The glaze portions of these color rendering ceramic tiles were completely melted, and a glossy glass layer was obtained. Next, each of the color rendering ceramic tiles of Example 7 was subjected to color measurement by using a Minolta spectrophotometer CM-3600d with three light sources of D65 light source, F10 light source and A light source. Table 1 shows the measured L ^* value, a ^* value, and b ^* value.

[0035]

[Table 1] As a result, when the chromaticity was examined from the a ^* value and the b ^* value of the two types of tiles, the D65 light source and the A light source showed yellow, and the F10 light source showed pink. In fact, the sample was yellow under sunlight and incandescent lamps and pink under three-wavelength fluorescent lamps. Further, these tiles were illuminated with a white fluorescent lamp or a black light to excite the afterglow phosphor. When the tiles were visually checked in the dark after the lighting was stopped, yellow green and red were visually observed.

(Example 8) Holmium oxide fine particles having an average particle diameter of 30 nm and Kamado feldspar were weighed at a weight ratio of 1: 1, respectively, and an appropriate amount of water and a binder (1% by weight of CM
C) was added and mixed in a mortar to prepare an undercolor. next,
The obtained undercolor was applied on a porcelain tile preliminarily calcined at 900 ° C. with a brush and dried. Then, Examples 1 to
A glaze having the same composition as in No. 4 was prepared, made into a slurry, applied to the surface of the pre-fired tile, and dried. The four types of tiles thus produced were fired in an oxidizing atmosphere at 1250 ° C. for 12 hours at a temperature of 1 hour and fired for 1 hour to produce color rendering ceramic tiles. The glaze portions of these color rendering ceramic tiles were completely melted, and a glossy glass layer was obtained. Next, each of the color-rendering ceramic tiles of Example 8 was applied to a Minolta-made spectrophotometer CM-
At 3600d, D65 light source, F10 light source, and A light source 3
Color measurement was performed with different types of light sources. L ^* value measured,
The a ^* value and the b ^* value are shown in Table 2, and a graph similar to the graph (shown in FIG. 2) showing the characteristics according to the difference in the light source in the color rendering test 1 was produced and shown in FIG.

[0037]

[Table 2]As a result, in each light source, a^*Value and b^*
The values showed little difference. In addition, D65 light source and
And A light source are relatively close a^*Value and b^*Have value
That is, it exhibited yellow chromaticity. On the other hand, the F10 light source
A compared to the light source ^*Large value b^*The value decreases and the pin
It showed the chromaticity of black color. In fact, all tiles are sun
It shows yellow under light and incandescent lamps, and under three-wavelength fluorescent lamps
Showed a pink color.

(Example 9) Ca- having the same composition as in Example 1
Prepare a Zn base glaze and add an average particle size of 3 to this base glaze.
μm holmium oxide fine particles (manufactured by Kojundo Chemical Laboratory)
And neodymium oxide fine particles having an average particle size of 3 μm (manufactured by Kojundo Chemical Laboratory) were added to prepare six types of formulations shown in Table 3. An appropriate amount of water was added to each of these formulations, and the mixture was sufficiently mixed using a porcelain mortar to prepare a glaze slurry.

[0039]

[Table 3] Subsequently, each glaze slurry was applied to the surface of the porcelain tile preliminarily calcined at 900 ° C. and dried, and then 1250 ° C.
The color rendering ceramic tile was manufactured by baking in an oxidizing atmosphere under the conditions of a temperature rise of 12 hours and a holding time of 1 hour.
In addition, the glaze portions of all these tiles were completely melted to obtain a glossy surface. Next, each of the color rendering ceramic tiles of Example 9 was applied to a Minolta spectrophotometer CM-
At 3600d, D65 light source, F10 light source, and A light source 3
Color measurement was performed with different types of light sources. The results (contents of holmium oxide and neodymium oxide, and L
^* Value, a ^* value and b ^* value) are shown in FIG.

As a result, L of the D65 light source and A light source^*Value
And b^*The values are relatively the same, but a ^*The value is better for A light source
A little higher. Also, only neodymium oxide was added
In the tile, a of the D65 light source and the A light source^*The value is F10
Although the value is larger than that of the light source, holmium oxide
Of the F10 light source as the blending ratio of^*The value increases rapidly
It's gone. Conversely, b^*Values are for neodymium oxide only
Tiles are large with F10 light source,
The value with D65 light source and A light source as the mixing ratio of um increases
Has grown. Actually, neodymium oxide only tile
Indicates light mauve under sunlight or incandescent light,
It showed blue under fluorescent light. Also, holmium oxide
Tiles only show yellow under sunlight or incandescent lights
Under a three-wavelength fluorescent lamp, the color was pink. Ma
Also, for tiles that mix both, under sunlight or incandescent light
Indicates a gray color and a light red-purple color under a three-wavelength fluorescent lamp.
Was.

Example 10 Ca of the same composition as in Example 1
-Prepare a Zn base glaze, and add praseodymium oxide fine particles (manufactured by Kojundo Chemical Laboratory) with an average particle diameter of 7 μm to this base glaze, and the content of praseodymium oxide is 10% by weight.
Was prepared. An appropriate amount of water was added to this mixture, and the mixture was sufficiently mixed using a porcelain mortar to prepare a glaze slurry.
Next, the glaze slurry is applied to a porcelain tile preliminarily baked at 900 ° C. and dried, and then fired in an oxidizing atmosphere at 1250 ° C. for 12 hours and heated for 1 hour to obtain a color rendering property. A ceramic tile was manufactured. In addition,
The glaze portion of this tile was completely melted to give a shiny surface. Next, the color rendering ceramic tile of Example 10 was measured using a Minolta spectrophotometer CM-3600d.
The colorimetry was performed using three types of light sources, a D65 light source, an F10 light source, and an A light source. Table 4 shows the results.

[0042]

[Table 4] From the results in Table 4, it was actually observed that the praseodymium oxide tile of Example 10 exhibited pale yellow-green under sunlight or an incandescent lamp and pale yellow under a three-wavelength fluorescent lamp. The same result as was obtained.

(Example 11) Ca of the same composition as in Example 1
-A Zn base glaze was prepared, and erbium oxide fine particles (manufactured by Shin-Etsu Chemical Co., Ltd.) having an average particle diameter of 7 µm were added to the base glaze to prepare a preparation having an erbium oxide content of 10% by weight. Using this composition, a color rendering ceramic tile was produced in the same manner as in Example 10. In addition, the glaze portion of this tile was completely melted to obtain a glossy surface. Next, the color rendering ceramic tile of this Example 11 was measured with a Minolta spectrophotometer CM-3600d using a D65 light source.
Colorimetry was performed using three types of light sources, the F10 light source and the A light source. Table 5 shows the results.

[0044]

[Table 5] From the results shown in Table 5, the erbium oxide tile of Example 11 exhibited a pink color under sunlight or an incandescent lamp, and showed a color of 3%.
Under the fluorescent light of wavelength, the result was similar to the result that was actually visually observed to show a light pink color.

Example 12 After soda lime glass was coated with holmium oxide fine particles having an average particle diameter of 30 nm, the holmium oxide fine particles were heated and melted at a high temperature of 500 ° C. or more using a separable burner to convert the holmium oxide fine particles into soda lime glass. And mixed and dispersed therein. Observation of the glass product after cooling revealed that holmium oxide was dispersed in the glass without being dissolved. When this glass product was observed with each light source, the holmium oxide fine particles in the glass showed yellow under sunlight or an incandescent lamp and pink under a three-wavelength fluorescent lamp.

Example 13 The effect of silicon oxide on color rendering was examined using holmium oxide fine particles having an average particle diameter of 30 nm. First, unfired holmium oxide fine particles, holmium oxide fine particles fired at 1230 ° C. for 1 hour, and three kinds of sample powders obtained by firing a mixture of the same molar mixture of holmium oxide fine particles and silicon oxide at 1230 ° C. for 1 hour were prepared. . Subsequently, after lightly pressing each sample powder, a spectral reflectometer (CMS manufactured by Murakami Color Research Laboratory)
-5000), and scanning was performed by irradiating light having a wavelength of 380 nm to 730 nm, and the spectral reflectance (%) was recorded. FIG. 5 shows the results.

As a result, when the spectral reflectances of the respective absorption peaks are compared, it can be seen that the reflectance of the fired fine particles is larger than that of the unfired fine particles, that is, the absorptance is lower. In particular, even at the absorption peak near 540 nm, which greatly affects the color rendering properties of holmium oxide, the reflectance of the fired fine particles is large, and a decrease in the color rendering properties due to firing is recognized. Looking at this decrease in color rendering properties in detail, the holmium oxide fine particles fired have an absorptivity of about 40% lower than that of the unfired holmium oxide fine particles, while the absorptivity of the mixture mixed with silicon oxide has a lower absorptivity. It can be seen that the decrease is significantly suppressed. The transition temperature of the holmium oxide particles from monoclinic to cubic is 97.
Considering that the temperature is 7 ° C., the color rendering property is remarkably lost at the time of phase transition when the holmium oxide fine particles are fired at a high temperature of 1000 ° C. or more, but the color rendering property is significantly reduced in the presence of silicon oxide. It was suggested that it could be suppressed.

Further, the mixture sample after the calcination was examined by X-ray diffraction, and it was confirmed that holmium silicate had been formed. Furthermore, even in the case of holmium oxide fine particles fired at 800 ° C. or lower in the absence of silicon oxide at a transition temperature, compared with unfired holmium oxide fine particles and holmium oxide fine particles fired at 1230 ° C. in the presence of silicon oxide. In each case, a slight decrease in color rendering properties was visually observed. Therefore, it was strongly suggested that holmium oxide can exhibit extremely good color rendering properties by firing at a high temperature of 1000 ° C. or higher (high temperature exceeding the transition temperature) in the presence of silicon oxide.

The present embodiment can be embodied with the following modifications. Addition of fine particles of rare earth element oxide to the ceramic raw material, firing after forming into a predetermined shape, further coloring the surface of the ceramic product with a coloring material containing fine particles of rare earth element oxide, and refiring. May produce a color rendering ceramic product.

Non-color rendering ceramic inorganic pigment or metal oxide may be added to the ceramic raw material for producing the first or second color rendering ceramic product. Alternatively, in order to manufacture the first or second color rendering ceramic product, the surface of the ceramic product may be further colored with a coloring material containing a non-color rendering ceramic inorganic pigment or metal oxide. Alternatively, a non-color-rendering ceramic inorganic pigment or metal oxide may be simultaneously added to the colorant used in producing the second color-rendering ceramic product.

Further, the technical ideas that can be grasped from the above embodiment will be described below. The color rendering ceramic product according to any one of claims 1 to 3, wherein the color rendering ceramic product is fired at a firing temperature of 500 to 1650 ° C.

The color rendering ceramic according to any one of claims 1 to 3, wherein an average particle diameter of the fine particles of the rare earth element oxide is larger than 0.1 µm and not larger than 20 µm. Product.

The color rendering ceramic product according to any one of claims 1 to 3, further comprising a non-color rendering ceramic pigment or metal oxide. The color rendering ceramic product according to any one of claims 1 to 3, wherein the color rendering ceramic product is fired at a firing temperature of 1000 to 1650 ° C in the presence of silicon oxide.

The ceramic product according to any one of claims 1 to 3, wherein the ceramic product is a ceramic or a fine ceramic. In the case of such a configuration, since the sintering is performed at a sintering temperature of 1000 to 1650 ° C. in the presence of silicon oxide, the color rendering ceramic product can exhibit extremely good color rendering properties.

The colorant according to claim 4, which is fired at a firing temperature of 500 to 1650 ° C. The average particle diameter of the fine particles of the rare earth element oxide is set to 0.
The coloring material according to claim 4, wherein the coloring material is in a range larger than 1 µm and not larger than 20 µm.

A ceramic raw material composition used for producing the color rendering ceramic product according to claim 1, wherein the fine particles of at least one rare earth element oxide selected from holmium, praseodymium, neodymium and erbium. A color rendering ceramic raw material composition characterized by containing, and firing after forming into a predetermined shape, whereby the color is reversibly changed according to the type of the external light source.

[0057]

As described above in detail, according to the present invention, the following effects can be obtained. According to the color rendering ceramic product of the invention described in claims 1 to 3, and the coloring material of the invention described in claim 4, the color rendering properties can be easily and inexpensively exhibited.

[Brief description of the drawings]

1A is a graph showing a colorimetric result of a color rendering test 1 of a tile of Example 1, and FIG. 1B is a graph showing a colorimetric result of a color rendering test of a tile of Example 6. FIG.

FIG. 2 is a graph showing characteristics of tiles according to Examples 1 to 5 due to differences in light sources.

FIG. 3 is a graph showing characteristics of tiles according to Example 8 depending on light sources.

FIG. 4 is a graph showing a color measurement result in a color rendering property test of the tile of Example 9.

FIG. 5 is a graph showing measurement results of spectral reflectance in Example 13.

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Claims (4)

[Claims] 1. A ceramic raw material containing fine particles of at least one rare earth element oxide selected from holmium, praseodymium, neodymium and erbium is manufactured by forming into a predetermined shape and then firing the same. A color rendering ceramic product characterized by a reversible color change in response to the change. 2. After applying a coloring material containing fine particles of at least one rare earth element oxide selected from holmium, praseodymium, neodymium and erbium to the surface of a ceramic molded body or fired body formed in a predetermined shape. ,
A color rendering ceramic product manufactured by firing and reversibly changing color according to the type of external light source. 3. The color rendering ceramic product according to claim 1, wherein an average particle diameter of the fine particles of the rare earth element oxide is in a range of 0.01 to 20 μm. 4. A coloring material used for producing the color rendering ceramic product according to claim 2, wherein fine particles of at least one rare earth element oxide selected from holmium, praseodymium, neodymium and erbium are used. A coloring material that contains and that reversibly changes color according to the type of external light source.