Ceramic products and decorative compositions

Abstract

To provide a ceramic product having a silver decoration part with good gloss and color development.SOLUTION: A ceramic product disclosed herein has a silver decoration part, the silver decoration part contains a noble metal component, and the noble metal component is mainly composed of a platinum component. Here, the 8° gloss value of the silver decoration part measured by the SCI method is 500 or more, and the 8°gloss value divided by the luminosity L*of the silver ornamental part when measured by the SCE method (8°gloss value / luminosity L*) is 11 or more.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a ceramic product and a decorative composition, and more particularly to a ceramic product having a silver decorative portion and a decorative composition for forming the silver decorative portion. [Background technology]

[0002] To give an elegant or luxurious impression, gold- or silver-colored decorative portions are sometimes formed on the surfaces of ceramic products such as porcelain, glassware, and enamelware. Such decorative portions are formed, for example, by applying a composition containing a metal organic compound such as a metal resinate to the surface of the ceramic product and firing it.

[0003] An example of a composition for forming a decorative portion having the above-described configuration is described in Patent Documents 1 and 2. Patent Documents 1 and 2 disclose a liquid gold for overglaze painting that contains gold (Au) as a main component and is used to form a gold-colored or silver-colored decorative portion. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 62-105990 [Patent Document 2] Japanese Patent Application Publication No. 6-48779 Summary of the Invention [Problem to be solved by the invention]

[0005] It is desirable that a ceramic product having the above-mentioned decorative portion gives an elegant or luxurious impression to the eye. As a result of extensive research by the present inventors, it was found that when only the gloss value, which indicates the gloss level, is adjusted, the amount of reflected light changes depending on the viewing angle, causing the silver to appear cloudy (dull and whitish), and the gloss (luster) of the silver decorative portion is not perceived sufficiently.

[0006] The present invention has been made in view of the above circumstances, and its main object is to provide a ceramic product having a silver-colored decorative portion that is visually superior in luster and color development, and another object is to provide a decorative composition that realizes the silver-colored decorative portion. [Means for solving the problem]

[0007] To achieve the above object, the ceramic product disclosed herein has a silver decorative part, and the silver decorative part contains a precious metal component, and the precious metal component is mainly composed of a platinum component. Here, the 8° gloss value of the silver decorative part when measured by the SCI method is 500 or more, and the 8° gloss value of the silver decorative part when measured by the SCE method is 500 or more. * Divided by (8° gloss value / lightness L * ) is 11 or greater. The ceramic product having such a configuration has a silver decorative part with sufficient luster because the 8° gloss value of the decorative part is 500 or more. * By ensuring that the ratio is 11 or more, a silver decorative portion that is not perceived as cloudy to the naked eye is realized. Therefore, with this configuration, it is possible to provide a ceramic product having a silver decorative portion that is perceived as having sufficient luster and color to the naked eye.

[0008] In a preferred embodiment of the ceramic product disclosed herein, the silver decorative portion has an area ratio of the noble metal component of 37% or more based on observation with a field emission scanning electron microscope (FESEM). According to this configuration, it is possible to provide a ceramic product having a silver decorative portion that has sufficient luster and color when visually inspected.

[0009] In the ceramic product disclosed herein, the precious metal component includes precious metal particles, and in an embodiment in which the area ratio of the precious metal component is 37% or more, the precious metal particles have a cumulative 50% particle diameter (D 50In another preferred embodiment, the noble metal particles may have a cumulative 90% particle diameter (D ) of 5 nm or more in a particle size distribution based on the number of particles. 90 In another preferred embodiment, the noble metal particles may have an arithmetic mean diameter of 35 nm or more.

[0010] In a preferred embodiment of the ceramic product disclosed herein, the sheet resistance of the silver decorative portion is 1×10 4 It is Ω / □ or more. With this configuration, a ceramic product is realized that has a silver decorative part that has sufficient luster and color when visually inspected, and that also has insulating properties that prevent sparks from occurring in a microwave oven.

[0011] To achieve the other object, a decorative composition is disclosed herein. The decorative composition disclosed herein is used for silver-coloring a ceramic substrate and includes at least a precious metal element and a matrix-forming element. The precious metal element includes at least Pt, and the matrix-forming element includes a first element and a second element. The first element includes at least one element selected from the group consisting of Si and Bi, and the second element includes at least one element selected from the group consisting of Al, Zr, Ti, and rare earth elements. In this case, the content of the precious metal element is 76 mol% or more and 95 mol% or less, and the content of the second element is 1.5 mol% or more, based on a molar ratio where the sum of the precious metal element and the matrix-forming element is 100 mol%. According to this configuration, it is possible to form a silver decorative portion that has sufficient luster and color when visually inspected.

[0012] In a preferred embodiment of the ceramic product disclosed herein, the content of the second element is 1.5 mol % or more and 15 mol % or less when the total of the noble metal element and the matrix-forming element is 100 mol %. This configuration makes it possible to suitably form a silver decorative portion that has a sufficient sense of luster and color development.

[0013] In a preferred embodiment of the ceramic product disclosed herein, the ceramic product has the following composition in molar ratio, where the total of the noble metal element and the matrix-forming element is 100 mol %: Pt 60mol%~95mol%, Au, Rh, Pd and Ag total 0mol%~20mol%, Si and Bi total 1mol%~16mol%, Al 0 mol% to 13 mol%, Zr 0mol% to 7mol%, Ti 0mol% to 7mol%, Rare earth elements 0mol%~7mol% (However, if Al is 10 mol% or more, rare earth elements must be 2 mol% or more.) It has. With this configuration, it is possible to form a silver decorative part that has sufficient luster and color to be visually perceived, and that has insulating properties that prevent sparks from occurring in a microwave oven. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is an FESEM observation image (20,000x) of the silver decorative portion according to Example 1. [Figure 2] 10 is an FESEM observation image (20,000x) of the silver decorative portion according to Example 11. [Figure 3] 1 is a binarized image of an FESEM observation image (20,000x magnification) of a silver decorative portion according to Example 1. [Figure 4] 10 is a binarized image of an FESEM observation image (20,000x magnification) of a silver decorative portion according to Example 11. DETAILED DESCRIPTION OF THE INVENTION

[0015] Preferred embodiments of the technology disclosed herein are described below. Matters necessary for implementation other than those specifically mentioned in this specification (e.g., a method for manufacturing a ceramic substrate to be decorated) can be understood based on the technical content taught by this specification and the general technical common sense of a person skilled in the art. The technology disclosed herein can be implemented based on the content disclosed in this specification and the general technical common sense of a person skilled in the art. The expression "A to B" used in this specification to indicate a range means greater than A and less than B. Therefore, it includes cases where the range is greater than A and less than B.

[0016] 1.Ceramic products An embodiment of the ceramic product disclosed herein will be described below. The ceramic product disclosed herein has a silver decorative portion containing a precious metal component. For example, the silver decorative portion may be provided on a substrate mainly composed of ceramic. Alternatively, for example, the substrate mainly composed of ceramic may have a coating layer mainly composed of an amorphous material (typically glass) and the silver decorative portion.

[0017] (1) Base material The substrate is a molded body primarily composed of ceramics (e.g., a molded body with a ceramic content of 50% by mass or more). Ceramics that make up such a substrate include silica (SiO2), alumina (Al2O3), zirconia (ZrO2), magnesia (MgO), titania (TiO2), ceria (CeO2), and yttria (Y2O3). The thickness, shape, hardness, and color of the substrate can be appropriately changed depending on the application of the ceramic product, and detailed description is omitted as they do not limit the technology disclosed herein. Note that the chemical formulas shown in parentheses after the above substance names indicate representative compositions of the substances and are not intended to limit the composition of actual ceramics to those chemical formulas.

[0018] (2) Coating layer The coating layer is a layer mainly composed of an amorphous material (e.g., glass) (e.g., a layer containing 50% or more by mass of amorphous material). Such a coating layer can be formed on the surface of the substrate for purposes such as protecting the substrate. Note that the coating layer is not essential and can be omitted in other forms. Such a coating layer is formed, for example, by applying a glaze to the surface of the substrate and then firing it. Here, the glaze is a chemical agent containing metallic and semi-metallic elements that become oxides upon firing and form an amorphous matrix. This glaze may contain the same elements as those contained in the amorphous region of the silver decorative portion, or it may contain different elements.

[0019] The composition of the coating layer is not particularly limited as long as it does not significantly impair the effects of the technology disclosed herein. Conventional components that can be used to protect ceramic substrates can be appropriately selected. For example, the coating layer may contain elements such as Si, Al, Fe, Mg, Na, Zn, K, Ca, and Sn. These elements may form a matrix in the form of amorphous oxides. Specifically, the coating layer may form an amorphous matrix containing elements such as silicon oxide (SiO), aluminum oxide (AlO), iron oxide (FeO), magnesium oxide (MgO), potassium oxide (NaO), zinc oxide (ZnO), potassium oxide (KO), calcium oxide (CaO), and tin oxide (SnO). The proportions of each element in the coating layer do not limit the technology disclosed herein, and therefore will not be described in detail.

[0020] (3) Silver decorative part The ceramic product disclosed herein has a silver decorative portion. The silver decorative portion can be formed on the surface of the substrate or the surface of the coating layer. The silver decorative portion of the ceramic product disclosed herein contains a precious metal component. The precious metal component can include precious metal particles. For example, the precious metal component may be composed of precious metal particles. Such a silver decorative portion has an 8° gloss value of 500 or more when measured by the SCI method, and a lightness L when the 8° gloss value is measured by the SCE method. * Divided by (8° gloss value / lightness L* ) is 11 or more. That is, the silver decorative part disclosed herein is a decorative part that has a glossy, well-colored silver color.

[0021] The glossiness of the silver decorative portion can be evaluated by the 8° gloss value (hereinafter simply referred to as "8° gloss value") measured using the SCI method. Here, "8° gloss value" is a value indicating glossiness, and the higher the 8° gloss value, the glossier and more lustrous the silver decorative portion. The 8° gloss value can be measured using a spectrophotometer (e.g., the CM-700d or CM-600d manufactured by Konica Minolta Sensing, Inc.) designed to approximate a 60° glossmeter based on JIS Z 8741:1997. The SCI (Specular Components Include) method is a measurement method that includes specular reflected light in the measurement.

[0022] In addition, the color development of the silver decorative parts is measured by the SCE method. * (Hereafter, simply "Lightness L * It can be evaluated by the L based on JIS Z 8781:2013. * a * b * In the color system, it is a value that indicates the degree of whiteness, and lightness L * The higher the value, the whiter the color. * Measurements can be made using a spectrophotometer that complies with JIS Z 8722:2009 (such as the CM-700d or CM-600d manufactured by Konica Minolta Sensing, Inc.). The SCE (Specular Components Exclude) method is a method that removes specular reflected light and measures only diffuse reflected light, and is also known as the diffuse reflectance measurement method. With the SCE method, measurements vary depending on the surface condition, even for the same color, and measurement results can be obtained that are close to those obtained when recognizing color visually.

[0023] The silver decorative portion of a ceramic product can be typically produced by applying the decorative composition described below to the surface of the ceramic substrate (or coating layer) and firing it. During this firing, the silver decorative portion, in which the precious metal particles are over-sintered, has a low 8° gloss value and a high lightness L * tends to be too high. This is presumed to be due to the following. For example, when a decorative composition with a high content of precious metal elements is applied to the substrate of a ceramic product (e.g., porcelain) and fired, the precious metal particles are likely to be over-sintered, and the aggregation of the precious metal particles makes it difficult for the precious metal components to disperse within the silver decorative portion. This reduces the color development in areas with little (or no) precious metal components, causing cloudiness and a corresponding decrease in gloss value (glossiness). Furthermore, when the precious metal particles are over-sintered, unevenness with differences in height occurs on the surface of the silver decorative portion, which can also impair the gloss value (glossiness). Furthermore, in areas with little (or no) precious metal components, the color of the substrate (e.g., white) is more likely to show through. For this reason, the lightness L * The gloss value is low and the lightness L * When the silver decorative portion has too high a gloss value, the silver luster is not felt sufficiently by the naked eye and it looks cloudy. * It has been found that by evaluating the silver decorative portion based on both of the above indices, a silver decorative portion that is free from cloudiness when visually observed and has a good sense of luster and color development can be realized.

[0024] Specifically, the silver decorative portion of the ceramic product disclosed herein has an 8° gloss value of 500 or more, and the 8° gloss value is less than the brightness L * Divided by (8° gloss value / lightness L * ) is 11 or more. The 8° gloss value of the silver decorative part is 500 or more, preferably 540 or more, may be 600 or more, may be 675 or more, may be 710 or more, may be 780 or more, may be 830 or more, or may be 900 or more. In addition, the 8° gloss value / lightness L *is 11 or more, preferably 11.5 or more, more preferably 20 or more, even more preferably 25.9 or more, and may be 33 or more, for example, 40 or more. Such a silver decorative part is a silver decorative part that is sufficiently glossy, has no cloudiness, and has good color development.

[0025] Lightness L * is not particularly limited as long as it is adjusted to satisfy the above value. * is, for example, preferably 10 or more, more preferably 20 or more, and may be 25 or more. * If the lightness L is too high, the silver tends to be whitish and cloudy, as mentioned above. * is preferably 55 or less, more preferably 45 or less, and even more preferably 35 or less. For example, the lightness L * is preferably about 20 or more and 45 or less.

[0026] In order for the silver decorative part to have a good silver color, it is necessary to meet the L standard based on JIS Z 8781:2013. * a * b * Chromaticity a in the color system * and chromaticity b * It is preferable that the chromaticity a is adjusted to a value that is neither too high nor too low. * and chromaticity b * indicates the color direction, and +a * is the red direction, -a * is the green direction, +b * -b is yellow direction * indicates the blue direction. * and chromaticity b * The measurement can be carried out using a spectrophotometer conforming to JIS Z 8722:2009. Although not particularly limited, the chromaticity a measured by the SCE method * (Hereafter, simply "chromaticity a *") is preferably, for example, -10 or more and 10 or less, and more preferably -5 or more and 7 or less. In addition, the chromaticity b * (Hereafter, simply "chromaticity b * ") is, for example, preferably -10 or more and 20 or less, more preferably -5 or more and 19 or less, and even more preferably -3 or more and 14 or less.

[0027] In order for the silver decorative portion to have suitable color development and luster, it is preferable that the precious metal particles are not oversintered, as described above, and that the precious metal components have a certain area ratio when viewed from above. In a preferred embodiment, the silver decorative portion of the ceramic product disclosed herein has an area ratio of the precious metal components of 37% or more based on observation with a field emission scanning electron microscope (FESEM). The area ratio of the precious metal components based on FESEM observation may be 39% or more, 43% or more, or even 50% or more. The upper limit of the area ratio of the precious metal components based on FESEM observation is preferably 90% or less, and may be 85% or less, from the viewpoint of ensuring the insulation properties described below.

[0028] Here, the "area ratio (%) of precious metal components based on FESEM observation" in this specification can be determined as follows. First, each sample is fixed horizontally on a sample stage with the surface of the silver decorative portion applied to the substrate facing up, and coated using an osmium plasma coater (e.g., OPC80N manufactured by Japan Laser Electronics Co., Ltd.) to prepare a measurement sample with an osmium-coated surface. The osmium coating conditions are, for example, a discharge voltage of 1.2 kV, a vacuum level of 6 to 8 Pa, and a coating time of 10 seconds. Next, using a field-emission scanning electron microscope (e.g., SU8230 manufactured by Hitachi High-Technologies Corporation), multiple random FESEM images (e.g., 3 to 20 images) of the surface of the silver decorative portion are acquired. Images are acquired by selecting areas that are free of scratches, impurities, or other obstacles to image analysis. The conditions for acquiring the FESEM images are, for example, an acceleration voltage of 10.0 kV and an emission current of 10±0.5 μA. The magnification of the field of view of the FESEM observation image may be adjusted appropriately so that the number of particles that can be counted in one field of view is 1000 to 10000, for example, 1000 times to 100000 times. Next, the acquired FESEM images are binarized using the well-known image processing software Image J (ver. 1.53e) so that the precious metal components appear black and other components (e.g., matrix-forming components) appear white. In the binarization process, the brightness threshold value determined by Image J's automatic settings can be used to distinguish between regions of precious metal components and regions of other components. The acquired FESEM images are then binarized by defining high-brightness regions (i.e., regions where the brightness threshold value is equal to or greater than the value determined by the automatic settings) as regions of precious metal components and low-brightness regions (i.e., regions where the brightness threshold value is less than the value determined by the automatic settings) as regions of other components. The threshold value determined by the automatic settings varies depending on the contrast and brightness of the acquired FESEM images, so is not particularly limited. However, for FESEM images acquired by the above method, a brightness value of 50 to 150 is generally set as the threshold. For each of the acquired FESEM images, the area of ​​the black portion relative to the area of ​​the entire FESEM image is calculated. Then, by calculating the average value of these values, the "area ratio (%) of the noble metal component based on FESEM observation" in this specification can be determined.

[0029] The precious metal component of the silver decorative portion of the ceramic product disclosed herein may contain precious metal particles. It is generally known that in a decorative film formed on a ceramic substrate, if the particle diameter of the precious metal particles contained in the decorative film becomes too small, the silver coloring property decreases, and the coloring is caused by the surface plasmon resonance of the precious metal particles (for example, if the precious metal particles are Pt particles, the coloring becomes more brownish). Therefore, even if the area ratio of the precious metal component based on FESEM observation is 37% or more, if the particle diameter of the precious metal particles that can constitute the precious metal component becomes excessively small (for example, if the area ratio of the precious metal component based on the number of precious metal particles is 37%, the coloring property of the precious metal component becomes too small (for example, if the area ratio of the precious metal component based on the number of precious metal particles is 37%), the coloring property of the precious metal component becomes too small (for example, if the area ratio of the precious metal component based on the number of precious metal particles is 37%). 50If the particle size is less than 5 nm, the silver coloring may be visually impaired. In other words, in order to achieve a silver decorative part with better coloring and luster, it is preferable that the particle size of the precious metal particles is not excessively small.

[0030] In a preferred embodiment, the precious metal particles contained in the precious metal component of the silver decorative portion of the ceramic product have a cumulative 50% particle diameter (D 50 ) is 5nm or more. D 50 For example, it is more preferable that the thickness is 8 nm or more, further preferably 11 nm or more, and may be 30 nm or more. 50 The upper limit of the thickness may be adjusted to satisfy the above-mentioned area ratio of the precious metal component, and is preferably 500 nm or less, more preferably 400 nm or less, and even more preferably 300 nm or less, thereby realizing a ceramic product having a silver decorative portion with good silver color development. In this specification, the term "cumulative 50% particle diameter in the particle size distribution based on the number (D 50 ) can be calculated as follows. First, the acquired FESEM observation image is binarized using Image J as described above. Next, the area of ​​the precious metal particles is measured using the "Analyze particles" function in Image J (ver. 1.53e). The measurement conditions should be set to 0-infinity for both size and circularity. The magnification of the FESEM image should be set so that the sintered precious metal particles can be accurately counted. For example, the magnification of the FESEM image should be adjusted so that the particle count in one field of view is 1,000 or more. At this time, particles present on the edge of the image should also be counted. On the other hand, if the particle count in one field of view is too high, the outlines of each precious metal particle may become blurred, making it difficult to accurately measure the area. Therefore, the magnification of the FESEM image should be adjusted so that the particle count in one field of view is 10,000 or less. Based on the area of ​​the precious metal particles, the circle-equivalent diameter of each precious metal particle can be calculated using the following equation (1). D = 2 × (π / S)0.5 (1) Here, D in formula (1) is the "circle equivalent diameter (nm)" and S is the "area (nm) of the precious metal particles obtained by image analysis processing." 2 )". Then, a number-based particle size distribution is created by arranging the calculated circle-equivalent diameters of at least 1,000 particles in order of particle size, and the particle diameter corresponding to a cumulative frequency of 50% by number in the particle size distribution is referred to as the "cumulative 50% particle diameter in the number-based particle size distribution (D 50 )"

[0031] In a preferred embodiment, the precious metal particles have a cumulative 90% particle diameter (D 90 ) is 20nm or more. D 90 is, for example, more preferably 35 nm or more, even more preferably 45 nm or more, and may be 50 nm or more. 90 The upper limit of the thickness may be adjusted to satisfy the above-mentioned area ratio of the precious metal component, and may be, for example, 800 nm or less, preferably 650 nm or less, and more preferably 500 nm or less. This allows for the realization of a ceramic product having a silver decorative portion with good silver color development. In this specification, the cumulative 90% particle diameter in the particle size distribution based on the number (D 90 ) can be determined as follows. First, the circle-equivalent diameter is calculated as described above in the FESEM observation image obtained above. Then, a number-based particle size distribution is created by arranging the calculated circle-equivalent diameters of at least 1,000 particles in order of particle size, and the particle diameter corresponding to a cumulative frequency of 90% by number in the particle size distribution is referred to as the "cumulative 90% particle diameter in the number-based particle size distribution" in this specification. 90 )"

[0032] In a preferred embodiment, the arithmetic mean diameter of the precious metal particles is 35 nm or more. The arithmetic mean diameter of the precious metal particles is, for example, more preferably 40 nm or more, even more preferably 50 nm or more, and may be 70 nm or more. On the other hand, the upper limit of the arithmetic mean diameter of the precious metal particles is not particularly limited, but is, for example, preferably 1250 nm or less, more preferably 500 nm or less, even more preferably 330 nm or less, and may be, for example, 280 nm or less. This allows for the realization of a ceramic product having a silver decorative portion with good silver color development. The "arithmetic mean diameter of the noble metal particles" in this specification can be determined as follows. First, the circle-equivalent diameter is calculated as described above for the acquired FESEM observation image. Then, the circle-equivalent diameters are calculated for at least 1,000 particles, and the average of the calculated circle-equivalent diameters is calculated, thereby determining the "arithmetic mean diameter of the noble metal particles."

[0033] In a preferred embodiment, the silver decorative portion of the ceramic product disclosed herein has insulating properties. In this specification, "having insulating properties" means that the sheet resistance is 1×10 4 A silver decorative part having such a sheet resistance has insulating properties that prevent sparks from occurring when heated in a microwave oven. The sheet resistance can be measured, for example, by the four-probe method. If the precious metal particles are over-sintered, a region where the precious metal particles are densely present may be formed. This may cause the silver decorative portion of the ceramic product to have electrical conductivity. Therefore, from the viewpoint of ensuring insulation, it is preferable to suppress the over-sintering of the precious metal particles.

[0034] The precious metal component of the silver decorative portion of the ceramic product disclosed herein is primarily composed of platinum. Herein, "the precious metal component is primarily composed of platinum" means that the Pt content (mol%) is the highest when the total amount of precious metal elements contained in the precious metal component is taken as 100 mol%. Preferably, the Pt content is 70 mol% or more when the total amount of precious metal elements contained in the precious metal component is taken as 100 mol%. The Pt content may be 75 mol% or more, 79 mol% or more, 85 mol% or more, 90 mol% or more, 95 mol% or more, or even 100 mol%. The Pt content is preferably 70 mol% or more to 100 mol%, more preferably 70 mol% or more to 99.5 mol%, and even more preferably 78 mol% or more to 99 mol%. This allows for a silver decorative portion with excellent color development. The content of each element in the silver decorative portion can be measured by elemental analysis using, for example, a general scanning electron microscope (SEM)-energy dispersive X-ray spectroscopy (EDX). The precious metal components contained in the silver decorative portion of the ceramic product disclosed herein may be composed of the precious metal elements contained in the decorative composition described below. In other words, the proportion of the precious metal elements in the silver decorative portion may roughly reflect the proportion of the precious metal elements in the decorative composition. Here, "precious metal elements" typically include platinum (Pt), gold (Au), rhodium (Rh), and silver (Ag). They may also include iridium (Ir), palladium (Pd), ruthenium (Ru), and osmium (Os).

[0035] The silver decorative portion may or may not contain Au, Rh, Pd, Ir, and Ag as the precious metal elements contained in the precious metal component. When the silver decorative portion contains the above precious metal elements, for example, the total of Au, Rh, Pd, Ir, and Ag is preferably 30 mol% or less, and more preferably 25 mol% or less. When Au is contained in the silver decorative portion, the content of Au may be 0.1 mol% to 25 mol% or less, or 3 mol% to 20 mol% or less, when the total of the precious metal elements contained in the precious metal component is 100 mol%. When Rh is contained in the silver decorative portion, the content of Rh may be 0.1 mol% to 7 mol% or less, or 0.5 mol% to 2 mol% or less, or 0.5 mol% to 1.5 mol% or less. When Ir is contained in the silver decorative portion, the Ir content may be 0.1 mol% to 7 mol%, 0.5 mol% to 2 mol%, or 0.5 mol% to 1.5 mol%. When Pd is contained in the silver decorative portion, the Pd content may be 0.1 mol% to 10 mol%, or 1 mol% to 7 mol%. When Ag is contained in the silver decorative portion, the Ag content may be 0.1 mol% to 12 mol%, or 1 mol% to 10 mol%.

[0036] The silver decorative portion is typically formed in the form of a film on the surface of the substrate (or coating layer) of the ceramic product. The average thickness of the silver decorative portion is not particularly limited, but is preferably 20 nm or more and 300 nm or less, and more preferably 50 nm or more and 150 nm or less. A silver decorative portion having such an average thickness will achieve a good silver color without the color of the ceramic substrate showing through. The average thickness of such a silver decorative portion can be appropriately adjusted, for example, by the application method.

[0037] 2. Decorative compositions One embodiment of the decorative composition disclosed herein is described below. By applying this decorative composition to the surface of a substrate (or coating layer) of a ceramic product and firing it, a ceramic product can be produced with a silver-colored decorative portion exhibiting excellent gloss and color development, as described above. The decorative composition disclosed herein contains at least a precious metal element and a matrix-forming element. The precious metal element includes at least platinum (Pt). The matrix-forming element includes at least a first element and a second element. The first element includes at least one element selected from the group consisting of silicon (Si) and bismuth (Bi). The second element includes at least one element selected from the group consisting of aluminum (Al), zirconium (Zr), titanium (Ti), and rare earth elements. Various components that may be included in the decorative composition disclosed herein are described in detail below.

[0038] (1) Noble metal elements The noble metal element is a component that contributes to the coloring of the fired body of the decorative composition (i.e., the silver decorative portion). As described above, the decorative composition disclosed herein contains at least Pt as a noble metal component. Specific examples of noble metal elements that may be included in addition to Pt include gold (Au), rhodium (Rh), silver (Ag), iridium (Ir), palladium (Pd), ruthenium (Ru), and osmium (Os). The noble metal element may be contained in the decorative composition in the form of, for example, a metal resinate (an organic metal compound). The state of the noble metal element in the decorative composition is not limited to the metal resinate described above, but may also be a complex, a polymer, or metal particles.

[0039] The decorative composition disclosed herein contains a precious metal element in an amount of at least 76 mol% or more, where the sum of the precious metal element and the matrix-forming element contained in the decorative composition is 100 mol%. The content of the precious metal element is preferably 79 mol% or more, more preferably 82 mol% or more, and may be 85 mol% or more, 90 mol% or more, or even 94 mol% or more. Furthermore, since the decorative composition disclosed herein contains a matrix-forming element, the content of the precious metal element is 97 mol% or less, may be 96 mol% or less, and preferably 95 mol% or less. By including a predetermined proportion of the second element described below, the decorative composition disclosed herein can prevent over-sintering of the precious metal particles, even in compositions with a high content of the precious metal element, resulting in a silver decorative portion with a clear, well-colored silver finish. In the following description, unless otherwise specified, the "content of a specific element in a decorative composition" refers to the content (mol%) of the specific element when the total of the precious metal element and matrix-forming element contained in the decorative composition is taken as 100 mol%.

[0040] Platinum (Pt) is the component that imparts the lustrous silver-like color tone to the silver decorative portion. Pt is the major constituent element among the precious metal elements contained in the decorative composition (i.e., the element with the highest content among the precious metal elements in the decorative composition). Pt is included in the decorative composition, for example, as a constituent element of Pt resinate. Pt resinate has the property of forming Pt particles with larger particle diameters than other precious metal elements upon firing. As a result, Pt particles are less likely to sinter than other precious metal elements. This makes it easier for Pt particles to be separated from one another in the decorative portion of the decorative composition, thereby suppressing electrical conductivity. As a result, the decorative composition disclosed herein can achieve a silver decorative portion that has favorable insulating properties and does not spark when heated in a microwave oven, even when the content of components that reduce electrical conductivity (e.g., matrix-forming components such as Si and Bi) in the silver decorative portion is low.

[0041] Among the above-mentioned precious metal elements, Pt is particularly preferred because it exhibits excellent color development, making it relatively easy to form silver decorative parts that give an elegant or luxurious impression. The Pt content in the decorative composition is preferably 60 mol% or more, more preferably 66 mol% or more, and may be 70 mol% or more, 80 mol% or more, or even 90 mol% or more. On the other hand, if the Pt content in the decorative composition is too high, the number of Pt particles in the silver decorative part will be excessively large. As mentioned above, Pt particles tend to have large particle diameters, which can cause unevenness with differences in height on the surface of the silver decorative part and impair gloss. Therefore, the Pt content in the decorative composition is suitably 97 mol% or less, may be 96 mol% or less, and preferably 95 mol% or less.

[0042] Gold (Au), rhodium (Rh), palladium (Pd), iridium (Ir), and silver (Ag) are components that adjust the silver hue in the fired product (i.e., the silver decorative portion) of the decorative composition. The decorative composition disclosed herein may or may not contain Au, Rh, Pd, Ir, and Ag. When Au is contained, the content of Au in the decorative composition is preferably 1 mol% to 20 mol%, and more preferably 3 mol% to 17 mol%. When Rh is contained, the content of Rh in the decorative composition is preferably 0.1 mol% to 5 mol%, and more preferably 0.8 mol% to 3 mol%. When Pd is contained, the content of Pd in ​​the decorative composition is preferably 0.1 mol% to 10 mol%, and more preferably 1 mol% to 8 mol%. When Ir is contained, the content of Ir in the decorative composition is preferably 0.1 mol% to 5 mol%, more preferably 0.8 mol% to 3 mol%.When Ag is contained, the content of Ag in the decorative composition is preferably 0.1 mol% to 10 mol%, more preferably 1 mol% to 8 mol%.

[0043] (2) Matrix-forming elements As used herein, the term "matrix-forming elements" encompasses metal elements and metalloid elements that can form an amorphous matrix in the fired body (silver decorative portion) of the decorative composition in their oxide form. Furthermore, the term "amorphous matrix" refers to a structure in which a framework is formed of amorphous oxides (oxides with an amorphous structure) of specific metal elements and metalloid elements, with various metal elements (or metalloid elements) present within the framework as oxides or cations. An example of a material having an amorphous matrix (amorphous material) is glass. Examples of such matrix-forming elements include Si, Bi, Zr, Ti, Al, Ni, Cr, Sm, Y, La, Ce, Pr, Nd, Sm, Dy, Sn, Zn, Be, Mg, Ca, Sr, Ba, Li, Na, K, Rb, B, V, Fe, Cu, P, Sc, Pm, Eu, Gd, Tb, Ho, Er, Tm, Yb, Lu, In, and Co. Among the noble metal elements mentioned above, there are elements (such as Ag) that can partially become amorphous oxides during firing and form part of the amorphous matrix. However, for the sake of convenience, the elements listed in (1) Noble Metal Elements above are not considered to be matrix-forming elements in this specification. As with the noble metal elements, the form of the matrix-forming components in the decorative composition is not particularly limited, and may take the form of metal resinates (organic metal compounds), complexes, polymers, fine particles (glass frit), etc.

[0044] The decorative composition disclosed herein contains matrix-forming elements. The matrix-forming elements include at least one first element selected from the group consisting of silicon (Si) and bismuth (Bi), and at least one second element selected from the group consisting of aluminum (Al), zirconium (Zr), titanium (Ti), and rare earth elements. The content of the matrix-forming elements in the decorative composition is preferably 3 mol% or more, more preferably 4 mol% or more, and even more preferably 5 mol% or more. Considering the balance with the above-mentioned precious metal elements, the content of the matrix-forming elements in the decorative composition is preferably 24 mol% or less, more preferably 21 mol% or less, and even more preferably 18 mol% or less.

[0045] (a) First element As described above, the decorative composition disclosed herein contains silicon (Si) and / or bismuth (Bi) as the first matrix-forming element. Si and Bi are components that form the framework of the amorphous matrix in the form of silicon oxide (SiO2) or bismuth oxide (Bi2O3) after firing. The content of the first element (i.e., the total content of Si and Bi) in the decorative composition is preferably 1 mol% or more, more preferably 1.4 mol% or more, and may be 3 mol% or more, and even more preferably 10 mol% or more. On the other hand, if the content of the first element is too high, the luster of the silver decorative portion may be lost. Therefore, the content of the first element in the decorative composition is preferably 16 mol% or less, and may be 13 mol% or less.

[0046] As described above, Si is a component that forms the framework of the amorphous matrix and can improve the strength of the silver decorative part. When Si is included as the first element, the Si content in the decorative composition is preferably 1 mol% to 16 mol%, more preferably 3 mol% to 14 mol%, and even more preferably 5 mol% to 11 mol%. Furthermore, Bi is a component that forms the framework of the amorphous matrix and has the effect of softening the amorphous matrix (glass), thereby improving adhesion to the substrate. When Bi is included as the first element, the Bi content in the decorative composition is preferably 0.1 mol% to 5 mol%, more preferably 0.3 mol% to 3 mol%, and even more preferably 1 mol% to 2 mol%.

[0047] (b) Second element As described above, the decorative composition disclosed herein contains at least one element selected from the group consisting of aluminum (Al), zirconium (Zr), titanium (Ti), and rare earth elements as the second matrix-forming element. By incorporating a predetermined amount of the second element into the decorative composition, a silver decorative part with a clear, silvery color and good color development can be achieved. While not intending to limit the technology disclosed herein, the reason for this effect is presumed to be as follows. As described above, if the decorative composition contains a high amount of precious metal elements, the precious metal particles may over-sinter during firing, reducing the color development of the silver decorative part. It is presumed that the second element (Al, Zr, Ti, rare earth element) can prevent such over-sintering of the precious metal particles. Therefore, even if the decorative composition contains a high amount of precious metal elements, by incorporating a predetermined amount of the second element, a silver decorative part with a clear, silvery color and good color development can be achieved.

[0048] If the content of the second element in the decorative composition is too low, the effect of preventing the above-mentioned over-sintering of the precious metal particles will not be fully achieved. Therefore, the content of the second element in the decorative composition is at least 1.5 mol% or more. The content of the second element in the decorative composition is 1.5 mol% or more, preferably 2 mol% or more, and may be 4 mol% or more, or 5 mol% or more. On the other hand, if the content of the second element in the decorative composition is too high, the content of the precious metal element will decrease, which may result in a decrease in color development. From this perspective, the content of the second element in the decorative composition is preferably 20 mol% or less, more preferably 15 mol% or less, and may be 10 mol% or less, or may be 9 mol% or less. By adjusting the content of the second element in the decorative composition within the above range, a silver decorative portion having the above-mentioned characteristics can be suitably realized.

[0049] The rare earth elements can be selected without limitation from scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu). Based on extensive research conducted by the present inventors, among the above rare earth elements, Y, Sm, Pr, Nd, La, Ce, Dy, and Ho are preferred. Furthermore, Y and Sm are particularly preferred because their inclusion as secondary elements in the decorative composition can fully demonstrate the above-mentioned effects.

[0050] As mentioned above, aluminum (Al) is a component that prevents the precious metal particles from over-sintering and improves the color development of the silver decorative part. When Al is included as a second element, the Al content in the decorative composition is preferably 1.5 mol% or more, more preferably 2.5 mol% or more, and even more preferably 5 mol% or more. This results in a silver decorative part that is free of cloudiness and has good color development. The Al content in the decorative composition is 16 mol% or less, preferably 13 mol% or less, and more preferably 10 mol% or less.

[0051] While an appropriate amount of Al can prevent the precious metal particles from over-sintering, experiments have confirmed that too much Al can cause the silver decorative portion to become conductive. Therefore, in a preferred embodiment, when the second element contains 10 mol% or more of Al, it is advisable to contain 2 mol% or more of the above-mentioned rare earth elements. This allows for the realization of a silver decorative portion with good color development and sufficient insulation.

[0052] In a preferred embodiment, the aluminum component in the decorative composition is preferably in the form of an organometallic compound or oxide fine particles. Examples of organometallic compounds include metal resinates and metal chelate compounds. Metal resinates contain aluminum as a constituent element and an organic compound, as described below. More specifically, the decorative composition may contain aluminum resinates or other such compounds. Metal chelate compounds are chelate compounds containing aluminum as a constituent element, such as aluminum ethylacetoacetate diisopropylate, aluminum tris(ethylacetoacetate), aluminum alkylacetoacetate diisopropylate, aluminum monoacetylacetonate bis(ethylacetoacetate), and aluminum tris(acetylacetonate). Furthermore, alumina (Al2O3) fine particles are preferably used as the oxide fine particles. The average particle diameter of such oxide fine particles is preferably between 25 nm and 100 nm. In this specification, the "average particle diameter of oxide fine particles" refers to the particle diameter (D) at which the cumulative volume is 50% in the volume-based particle size distribution based on the laser diffraction / scattering method. 50 )

[0053] When zirconium (Zr), titanium (Ti) and rare earth elements are contained in the decorative composition in appropriate amounts, they prevent the precious metal particles from over-sintering as described above and improve the color development of the silver decorative parts. When Zr is included as the second element, the Zr content in the decorative composition is preferably 0.1 mol% to 7 mol%, and more preferably 1 mol% to 6.5 mol%. When Ti is included as the second element, the Ti content in the decorative composition is preferably 0.1 mol% to 7 mol%, and more preferably 1 mol% to 6.5 mol%. When a rare earth element is included as the second element, the rare earth element content in the decorative composition is preferably 0.1 mol% to 7 mol%, and more preferably 0.7 mol% to 7 mol%, and even more preferably 2 mol% to 6.5 mol%.

[0054] (c) Other elements The decorative composition disclosed herein may contain metal elements or metalloid elements other than those mentioned above as matrix-forming elements, provided that the effects of the technology disclosed herein are not impaired. Examples of such elements include Sn, Zn, Be, Mg, Ca, Sr, Ba, Li, Na, K, Rb, B, V, Fe, Cu, and P. The decorative composition does not necessarily contain such elements. If the decorative composition contains such elements, the content of such elements in the decorative composition may be 3 mol % or less, or even 2.5 mol % or less.

[0055] (3) Other ingredients The above describes the precious metal elements and matrix-forming elements of the decorative composition disclosed herein. In addition to the above-mentioned components, the decorative composition disclosed herein preferably contains various other components in consideration of the adhesion to the surface of the ceramic product (more specifically, the substrate or coating layer) and the formability of the decorative portion. Below, we will explain other components that may be included in the decorative composition disclosed herein. However, the other components described below can be any conventionally known components that can be used in decorative compositions, without any particular restrictions, as long as they do not significantly impede the effects of the technology disclosed herein. In other words, the decorative composition disclosed herein can be modified in components other than the above-mentioned essential elements as appropriate depending on its intended use.

[0056] First, as described above, the decorative composition disclosed herein may contain both a noble metal element and a matrix-forming element in the form of a metal resinate. In this case, the decorative composition contains an organic compound for forming the metal resinate. Any conventionally known resin material that can be used to form a metal resinate can be used as the organic compound, without particular limitation. Examples of such resin materials include carboxylic acids with a high carbon number (e.g., 8 or more carbon atoms), such as octylic acid (2-ethylhexanoic acid), abietic acid, naphthenic acid, stearic acid, oleic acid, linolenic acid, and neodecanoic acid; sulfonic acids; resin acids contained in rosin; resin sulfur balsams containing essential oil components such as turpentine oil and lavender oil; alkyl mercaptides (alkylthiolates); aryl mercaptides (arylthiolates); mercaptocarboxylic acid esters; and alkoxides.

[0057] In addition, in decorative compositions containing both a noble metal element and a matrix-forming element in the form of a metal resinate, an organic solvent that disperses or dissolves the metal resinate is preferably used. Such organic solvents can be any of those conventionally used in resinate pastes or liquid gold solutions, without any particular restrictions. Examples of organic solvents include 1,4-dioxane, 1,8-cineole, 2-pyrrolidone, 2-phenylethanol, N-methyl-2-pyrrolidone, p-tolualdehyde, benzyl benzoate, butyl benzoate, eugenol, caprolactone, geraniol, methyl salicylate, cyclohexanone, cyclohexanol, cyclopentyl methyl ether, citronellal, di(2-chloroethyl)ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, dihydrocarvone, dibromomethane, dimethyl sulfoxide, dimethylformamide, nitrobenzene, pyrrolidone, propylene glycol monophenyl ether, pulegone, benzyl acetate, benzyl alcohol, benzaldehyde, turpentine oil, and lavender oil. These organic solvents may be used alone or in combination. Metal resinates are commercially available as resinate pastes, and these resinate pastes may be used as they are.

[0058] The weight ratio of the solvent that can be contained in the decorative composition is not particularly limited, as the preferred range varies depending on the application method of the decorative composition, and can be adjusted as appropriate. For example, the weight ratio of the solvent should be approximately 10 wt% to 50 wt% when the entire decorative composition is taken as 100 wt%. For example, when applying by inkjet, the weight ratio of the solvent should preferably be 10 wt% to 50 wt% when the entire decorative composition is taken as 100 wt%. For example, when applying by brush, the weight ratio of the solvent should preferably be 10 wt% to 30 wt% when the entire decorative composition is taken as 100 wt%.

[0059] The viscosity of the decorative composition is not particularly limited and can be adjusted as needed depending on the application method of the decorative composition. The viscosity of the decorative composition may be, for example, about 10 mPa·s to 500 mPa·s. The viscosity of the decorative composition can be adjusted as needed by adjusting the amount of solvent or adding resin balsam.

[0060] The decorative composition disclosed herein may contain other components as appropriate, provided that the effects of the technology disclosed herein are not significantly impaired. Examples of such additional components include organic binders, protective materials, surfactants, dispersants, thickeners, pH adjusters, preservatives, antifoaming agents, plasticizers, stabilizers, and antioxidants.

[0061] The decorative composition disclosed herein can be produced, for example, by mixing materials containing desired metal elements in a predetermined ratio so as to contain at least a precious metal component and a matrix-forming component. As mentioned above, the form of the precious metal component and matrix-forming component contained in the decorative composition disclosed herein is not limited to metal resinates, but may also be complexes, polymers, or fine particles. When the precious metal component and matrix-forming component are in a form other than metal resinates, it is preferable to appropriately change the solvent and additional components described above depending on the form of the precious metal component and matrix-forming component. For example, when the precious metal component and matrix-forming component are contained in a form that is insoluble in a solvent, such as fine particles, it is preferable to select a solvent that can appropriately disperse the fine particles and to add a dispersant or other additional component.

[0062] 3. Manufacturing methods for ceramic products Next, an example of a method for producing the ceramic product disclosed herein will be described. Note that the ceramic product disclosed herein is not limited to those produced by the following production method.

[0063] (1) Preparation of the substrate When manufacturing the ceramic product according to this embodiment, first, a desired substrate is prepared. For example, the substrate can be prepared by molding and firing a substrate material prepared by kneading predetermined ceramic materials. A substrate with a coating layer can also be prepared by applying a glaze to the surface of the fired substrate and then firing it again. However, this process is not particularly limited as long as the substrate can be prepared. For example, a separately prepared substrate may be purchased and prepared.

[0064] (2) Formation of silver decorative parts Next, in the production of the ceramic product according to this embodiment, a silver decorative portion is formed on the substrate (or coating layer). This silver decorative portion can be formed by applying (applying) the decorative composition described above to the surface of the substrate or coating layer, followed by firing at a predetermined temperature. A suitable example of the firing process in this step is the use of the decorative composition disclosed herein for "overglaze painting," which involves decorating a substrate with a coating layer after a glaze has been applied. In overglaze painting, the decorative composition is applied to the surface of the glaze, followed by firing at a medium temperature of approximately 700°C to 1000°C. The decorative composition disclosed herein can also be used for "underglaze painting," which involves decorating a bisque-fired substrate (ceramic substrate). In underglaze painting, the decorative composition is applied to the substrate, followed by firing at a high temperature of approximately 1200°C to 1400°C. Examples of methods for applying the decorative composition include brush painting, screen printing, and inkjet printing.

[0065] In this manner, ceramic products having a silver decorative portion that is glossy, clear, and has good color development can be realized. Furthermore, decorative compositions that suitably form such silver decorative portions can also be realized. As mentioned above, "ceramic products" include pottery, porcelain, earthenware, stoneware, glass, and the like. Specific examples of such products include tableware, decorative utensils, various tiles, sanitary ware, roofing tiles, bricks, clay pipes, and ceramic pipes. In particular, the technology disclosed herein suitably realizes tableware having a silver decorative portion that is glossy, clear, and has good color development.

[0066] <Test example> Test examples relating to the technology disclosed herein will be described below, but it is not intended that the technology disclosed herein be limited to such test examples.

[0067] 1. Examination of the structure of the silver decorative part In this test, ceramic products with silver decorative parts were produced and the properties of the silver decorative parts were evaluated. Specifically, the glossiness (8° gloss value) and color development (8° gloss value / lightness L * ) and field emission scanning electron microscope (FESEM) observations were carried out. The structure of the silver decorative part, which has good color development and luster, was then investigated.

[0068] (1) Preparation of decorative composition In this test, the precious metal elements and matrix-forming elements were mixed to obtain the composition shown in Table 1. Each value in Table 1 represents the content (mol%) of each element when the total of the precious metal elements and matrix-forming elements contained in the decorative composition is taken as 100 mol%. Each decorative composition was prepared in the same manner as described above. In this manner, decorative compositions of Examples 1 to 20 were prepared. The raw materials of the precious metal components and matrix-forming components used here are shown below. Pt: Pt resinate (platinum resin sulfide balsam) Rh: Rh resinate (rhodium resin sulfide balsam) Au: Au resinate (gold resin sulfide balsam) Si:Si resinate (silicon resin acid salt) Bi: Bi resinate (bismuth resinate) Al-1: Al resinate (aluminum resinate) Al-2:Al2O3 nanoparticle slurry (average particle size 50nm) Al-3: Aluminum chelate compound (ALCH) Zr: Zr resinate (zirconium resinate) Y:Y resinate (yttrium resinate) Ca: Ca resinate (calcium resinate)

[0069] [Table 1]

[0070] (2) Applying the decorative composition and firing A white porcelain plate (length: 15 mm, width: 15 mm) with a glaze applied to its surface was prepared as the substrate with a coating layer, and the decorative composition prepared above (any of Examples 1 to 20) was applied (sprayed) onto the entire surface of one side of the white porcelain plate. The thickness of the silver decorative portion after firing was adjusted to 50 to 150 nm. A spin coater (Opticoat MS-A-150) manufactured by Mikasa Co., Ltd. was used to apply the decorative composition, and spin conditions were set at 5000 rpm for 10 seconds. The white porcelain plate with the decorative composition applied was dried on a hot plate at 60°C for 1 hour, and then fired at 800°C for 10 minutes. This resulted in the white porcelain plates (ceramic products) of Examples 1 to 20 with silver decorative portions formed on their surfaces.

[0071] (3) Gloss and color development evaluation The 8° gloss value of the white porcelain plate with silver decoration and L * value, a * value, b * The 8° gloss value was measured using a spectrophotometer (CM-700d, manufactured by Konica Minolta Sensing Co., Ltd.) conforming to JIS Z 8722:2009. The 8° gloss value was measured using the SCI method, and the L * value, a * value, b * The values ​​were measured using the SCE method. Also, the 8° gloss value and brightness L * From, 8° gloss value / lightness L * The 8° gloss value is 500 or more and the 8° gloss value / lightness L is * The silver decorative parts with a score of 11 or more were evaluated as having good luster and color development. The results are shown in Table 2.

[0072] (4) FESEM observation FESEM observations were performed on white porcelain plates with silver decorative portions. First, each sample was fixed horizontally on a sample stage with the side coated with the decorative composition (i.e., the surface of the silver decorative portion) facing up. An osmium plasma coater (OPC80N, manufactured by Japan Laser Electronics Co., Ltd.) was used to coat the sample to prepare a measurement sample with an osmium-coated surface. The discharge voltage for the osmium coating was 1.2 kV, the vacuum level was 6 to 8 Pa, and the coating time was 10 seconds. Next, five FESEM images of the surface of the silver decorative portion were obtained using a field-emission scanning electron microscope (SU8230, manufactured by Hitachi High-Technologies Corporation). The accelerating voltage and emission current for the FESEM images were 10.0 kV and 10 ± 0.5 μA, respectively. The magnification of the field of view was adjusted from 2000x to 100,000x, so that the number of countable particles in one field of view was 1,000 to 10,000. As an example, FESEM observation images of Examples 1 and 11 are shown in FIGS.

[0073] Next, the five FESEM images were binarized using the well-known image processing software Image J (ver. 1.53e) so that the precious metal components were black and other components (e.g., matrix-forming components) were white. As an example, the binarized images for Examples 1 and 11 are shown in Figures 3 and 4. The brightness threshold used to distinguish the precious metal component regions from the other components in the FESEM images was determined using the Image J auto setting. Regions above the brightness threshold were designated as the precious metal component regions, and regions below the brightness threshold were designated as the other components, and binarization was performed. The area of ​​the black portion of each of the five FESEM images relative to the total area of ​​the FESEM image was calculated. The area ratio (%) of the precious metal components based on the FESEM observation was then calculated by averaging these values. The results are shown in Table 2.

[0074] In addition, the area of ​​each particle was measured using the "Analyze particles" function of the well-known image processing software Image J (ver. 1.53e) for the FESEM observation images of each example obtained above, and the cumulative 50% particle diameter (D 50 ), cumulative 90% particle diameter in the particle size distribution based on the number (D 90 ) and arithmetic mean diameter were calculated. The measurement conditions at this time were set to 0-infinity for both size and circularity. Then, a particle size distribution based on the number of particles was created by arranging the calculated circle equivalent diameters of at least 1,000 particles in order of particle size, and the particle diameter corresponding to a cumulative frequency of 50% by number in the particle size distribution was defined as D 50 The particle diameter corresponding to a cumulative frequency of 90% by number is D 90 The average value of the equivalent circle diameters of at least 1,000 particles was taken as the arithmetic mean diameter.

[0075] [Table 2]

[0076] As shown in Table 2, in Examples 3 to 5 and Examples 9 to 19, the 8° gloss value was 500 or more, and the 8° gloss value / lightness L * It can be seen that the silver decorative portions of the ceramic products of Examples 3 to 5 and Examples 9 to 19 are silver decorative portions with good color development and luster. It can also be seen that the area ratio of the precious metal component in Examples 3 to 5 and Examples 9 to 19 is 37% or more based on FESEM observation. Furthermore, in Examples 3 to 5 and Examples 9 to 19, the area ratio of the precious metal component is 37% or more, and D 50 In addition, in Examples 3 to 5 and Examples 9 to 19, the area ratio of the noble metal component is 37% or more, and D 90 It can be seen that in Examples 3 to 5 and Examples 9 to 19, the area ratio of the noble metal component is 37% or more and the arithmetic mean diameter is 35 nm or more.

[0077] As shown in Tables 1 and 2, in Examples 3 to 5 in which decorative compositions containing 50 mol % to 75 mol % of precious metal elements were fired, the 8° gloss value was 500 or more, and the 8° gloss value / brightness L * On the other hand, in Examples 1 and 2, which were prepared by firing decorative compositions containing 76 mol% or more of precious metals and no second element, and Examples 6 and 7, which were prepared by firing decorative compositions containing a small amount of precious metals, the 8° gloss value was less than 500, and the 8° gloss value / lightness L * It can be seen that the value is less than 11. When a decorative composition with a precious metal content of 76 mol% or more is fired to form a silver decorative part, it is presumed that the color development is poor because the precious metal particles are over-sintered. On the other hand, when a decorative composition with a low content of precious metal elements is fired to form a silver decorative part, it is presumed that the color development is poor because the parts derived from the precious metal elements become thinner and the color of the base is visible through.

[0078] As shown in Tables 1 and 2, even though the content of the precious metal element is 76 mol % or more, the silver decorative parts of Examples 9 to 19, which were obtained by firing decorative compositions containing 1.5 mol % or more of at least one element selected from the group consisting of Al, Zr, Ti and rare earth elements as the second element, have an 8° gloss value of 500 or more, and a 8° gloss value / lightness L * On the other hand, in Example 8, in which the content of the second element is 1.5 mol % or less, and Example 20, which does not contain the second element as a matrix forming element, the 8° gloss value is less than 500, and the 8° gloss value / lightness L * It can be seen that the value is less than 11. When the second element is not contained in an amount of 1.5 mol% or more, or when Ca is used as in Example 20, it is presumed that the effect of suppressing the over-sintering of the precious metal particles as described above is insufficient, and therefore the effect of improving the gloss and color development of the silver decorative portion is not exhibited. Therefore, a decorative composition containing a precious metal element including at least Pt, a first element including at least one of Si and Bi as a matrix-forming element, and a second element including at least one selected from the group consisting of Al, Zr, Ti and rare earth elements, in which the content of the precious metal element is 76 mol% or more and 95 mol% or less and the content of the second element is 1.5 mol% or more, can form a silver decorative portion of a ceramic product with good color development and luster.

[0079] 2. Examination of the type and content of secondary elements Based on the above-mentioned investigation, in this test, the 8° gloss value and the 8° gloss value / lightness L were measured for a fired body (silver decorative part) of a decorative composition containing at least a precious metal element and a matrix-forming element, and the precious metal content was 76 mol% or more. * In this test, in addition to the decorative compositions (Examples 1 to 20) examined in the above test, six decorative compositions (Examples 21 to 26) with different compositions were prepared, and the gloss (8° gloss value) and color development (8° gloss value / lightness L * ) and insulating properties were evaluated. In Examples 21 to 26, the precious metal elements and matrix-forming elements were mixed to obtain the compositions shown in Table 3. Each value in Table 3 represents the content (mol%) of each element when the total of the precious metal elements and matrix-forming elements contained in the decorative composition is taken as 100 mol%.

[0080] (1) Preparation of decorative composition Each decorative composition was prepared in the same manner as described above. In this manner, decorative compositions of Examples 21 to 26 were prepared. The raw materials of the precious metal components and matrix-forming components used here are shown below. Pt: Pt resinate (platinum resin sulfide balsam) Rh: Rh resinate (rhodium resin sulfide balsam) Au: Au resinate (gold resin sulfide balsam) Si:Si resinate (silicon resin acid salt) Bi: Bi resinate (bismuth resinate) Al-3: Aluminum chelate compound (ALCH) Ti: Titanium resinate Y:Y resinate (yttrium resinate) Sm: Sm resinate (samarium resinate) Mg: Mg resinate (magnesium resinate)

[0081] [Table 3]

[0082] (2) Applying the decorative composition and firing A white porcelain plate (length: 15 mm, width: 15 mm) with a glaze applied to its surface was prepared as the substrate with a coating layer, and the decorative composition prepared above (any of Examples 21 to 26) was applied (sprayed) onto the entire surface of one side of the white porcelain plate. The composition was adjusted so that the silver decorative portion after firing would be 50 to 150 nm. The decorative composition was applied in the same manner as described above. The white porcelain plate with the decorative composition applied was dried on a hot plate at 60°C for 1 hour, and then fired at 800°C for 10 minutes. This resulted in the white porcelain plates (ceramic products) of Examples 21 to 26 with silver decorative portions formed on their surfaces.

[0083] (3) Evaluation of gloss and color development The white porcelain plates (Examples 21 to 26) on which the silver decorative parts were formed were * value, a * value, b * The 8° gloss value was measured using the above-mentioned spectrophotometer. The 8° gloss value was measured using the SCI method, and the L * value, a * value, b * The values ​​were measured using the SCE method. Also, the 8° gloss value and brightness L * From, 8° gloss value / lightness L * The 8° gloss value is 500 or more and the 8° gloss value / lightness L is *Silver decorative portions with a value of 11 or more were evaluated as having good gloss and color development. The results are shown in Table 4. For comparison, Table 4 also shows the measurement results of Examples 1 to 20.

[0084] (4) Evaluation of insulation properties The sheet resistance (Ω / □) of the white porcelain flat plates (Examples 1 to 26) on which the silver decorative portions were formed was measured. The sheet resistance was measured by the four-probe method using a resistivity meter (Loresta GP MCP-T610) manufactured by Mitsubishi Chemical Analytech Co., Ltd. 4 Those with a value of Ω / □ or higher were evaluated as having sufficient insulation. The results are shown in Table 4.

[0085] [Table 4]

[0086] As shown in Table 4, in Examples 3 to 5, 9 to 19, and 21 to 24, the 8° gloss value is 500 or more, and the 8° gloss value / lightness L * is 11 or more, and the sheet resistance is 1×10 4 It can be seen that the resistance is Ω / □ or more. Therefore, it can be seen that the silver decorative parts of the ceramic products of Examples 3 to 5, 9 to 19, and 21 to 24 are silver decorative parts with good color development and luster, and further have sufficient insulation properties.

[0087] As shown in Tables 1, 3, and 4, even though the content of the precious metal element is 76 mol% or more, the silver decorative portions of the ceramic products of Examples 9 to 19 and Examples 21 to 25, which were obtained by firing a decorative composition containing 1.5 mol% or more of at least one element selected from the group consisting of Al, Zr, Ti, and rare earth elements as a second element, have an 8° gloss value of 500 or more, and a 8° gloss value / lightness L *Furthermore, when the second element contained 10 mol% or more of Al, the silver decorative portions of the ceramic products of Examples 9 to 19 and Examples 21 to 24, which were obtained by firing decorative compositions containing 2 mol% or more of a rare earth element as the second element, had a sheet resistance of 1×10 4 It can be seen that it is Ω / □ or more. Therefore, a decorative composition containing at least Pt, a first element containing at least one of Si and Bi as a matrix-forming element, and a second element containing at least one selected from the group consisting of Al, Zr, Ti, and rare earth elements, with a content of 76 mol% to 95 mol% of the precious metal element and 1.5 mol% or more of the second element, can form a silver decorative portion of a ceramic product with good color and luster. Furthermore, when the decorative composition contains 10 mol% or more of Al as the second element, a decorative composition containing 2 mol% or more of a rare earth element as the second element can form a silver decorative portion of a ceramic product with good color and luster and sufficient insulation.

[0088] While specific examples of the technology disclosed herein have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and alterations of the specific examples exemplified above.

Claims

1. A decorative composition used for silver decoration of a ceramic substrate, Contains at least a noble metal element and a matrix-forming element, the noble metal element includes at least Pt; the matrix-forming elements include a first element and a second element, The first element includes Si and Bi, The second element includes at least one element selected from the group consisting of Al, Zr, Ti, and rare earth elements, Here, in the molar ratio where the total of the noble metal element and the matrix-forming element is 100 mol %, The content of the noble metal element is 76 mol% or more and 95 mol% or less, A decorative composition having a content of the second element of 1.5 mol % or more.

2. 2. The decorative composition according to claim 1, wherein the content of said second element is 1.5 mol % or more and 15 mol % or less when the total of said noble metal element and said matrix-forming element is taken as 100 mol %.

3. In a molar ratio where the total of the noble metal element and the matrix-forming element is 100 mol %, Composition of: Pt 60 mol% to 95 mol%, A total of 0 mol % to 20 mol % of Au, Rh, Pd and Ag, a total of Si and Bi of 1 mol% to 16 mol%; Al 0 mol% to 13 mol%, Zr 0 mol% to 7 mol%, Ti 0 mol% to 7 mol%, Rare earth elements 0 mol% to 7 mol% (However, when Al is 10 mol % or more, the rare earth element is 2 mol % or more.) The decorative composition according to claim 1 or 2, wherein

4. A ceramic substrate; A ceramic product comprising: a silver decorative portion formed on the ceramic substrate, the silver decorative portion being a fired body of the decorative composition according to any one of claims 1 to 3; The silver decorative portion contains a precious metal component, The 8 ° gloss value of the silver decorative part when measured by the SCI method is 500 or more, and A ceramic product in which the value (8° gloss value / lightness L*) obtained by dividing the 8° gloss value by the lightness L* of the silver decorative portion measured by the SCE method is 11 or more.

5. A ceramic product as described in claim 4, wherein the area ratio of the precious metal component in the silver decorative portion based on observation with a field emission scanning electron microscope (FESEM) is 37% or more.

6. The precious metal component comprises precious metal particles, The ceramic product according to claim 5 , wherein the noble metal particles have a cumulative 50% particle diameter (D 50 ) of 5 nm or more in a number-based particle size distribution.

7. The precious metal component comprises precious metal particles, The ceramic product according to claim 5 , wherein the noble metal particles have a cumulative 90% particle diameter (D 90 ) of 20 nm or more in a number-based particle size distribution.

8. The precious metal component comprises precious metal particles, The ceramic product according to claim 5 , wherein the noble metal particles have an arithmetic mean diameter of 35 nm or more.

9. The ceramic product according to claim 4, wherein the sheet resistance value of the silver decorative portion is 1×10 4 Ω / □ or more.

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