Decorative compositions and ceramic products

Abstract

The decorative composition disclosed herein is used for silver decoration of a ceramic substrate, and includes a precious metal element and a matrix-forming element. The precious metal element includes a first element consisting of Pt, a second element consisting of Rh, and a third element consisting of at least one of Pd and Ir. The matrix-forming element includes Bi. In this case, the content of the precious metal element is 80 mol % or more, and the total content of the second element and the third element is 6 mol % or more and 60 mol % or less, in a molar ratio where the sum of the precious metal element and the matrix-forming element is 100 mol %.

Description

[Technical field]

[0001] The present invention relates to a decorative composition and a ceramic product. This application claims priority based on Japanese Patent Application No. 2023-103893 filed on June 26, 2023, the entire contents of which are incorporated herein by reference. [Background technology]

[0002] On the surface of ceramic products such as porcelain, glassware, and enamelware, a gold- or silver-colored decorative part may be formed to give an elegant or luxurious impression. Such a decorative part is 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. For example, Patent Documents 1 to 3 disclose examples of compositions for forming such decorative parts on ceramics and the like. Patent Document 1 discloses a composition containing 75% or more gold (Au) and forming a decorative white gold alloy. Patent Document 2 discloses a composition containing platinum (Pt), palladium (Pd), gold (Au), and bismuth (Bi) as essential components and forming a microwave-safe platinum-colored decorative part. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2008-214718 A [Patent Document 2] JP 2001-130985 A [Patent Document 3] Japanese Patent Application Publication No. 01-000179 Summary of the Invention

[0004] In recent years, the price of gold has been rising, and decorative compositions are being considered for a change from compositions with a high gold content to compositions with a higher platinum or silver content than before. However, according to the results of the inventors' investigations, it was found that compositions containing more platinum than before cause the silver color to darken and the luster to be impaired in the decorative parts after firing.

[0005] The present invention has been made in consideration of the above-mentioned circumstances, and its main object is to provide a silver decorative part having excellent color development and gloss, and a decorative composition for realizing such a silver decorative part.

[0006] In order to achieve the above object, the decorative composition disclosed herein is used for silver decoration of a ceramic substrate, and includes a precious metal element and a matrix-forming element. The precious metal element includes a first element consisting of Pt, a second element consisting of Rh, and a third element which is at least one selected from the group consisting of Pd and Ir. The matrix-forming element includes Bi. In this case, the content of the precious metal element is 80 mol % or more, and the total of the second element and the third element is 6 mol % or more and 60 mol % or less, in a molar ratio where the sum of the precious metal element and the matrix-forming element is 100 mol %.

[0007] When a composition containing Pt, Rh, Pd, and Ir is fired, Rh, Pd, and Ir adhere to the periphery of Pt particles in the form of oxides during firing, suppressing the aggregation of Pt particles. This suppresses the Pt particles from becoming coarse due to firing. In addition, since the Pt particles do not aggregate, the Pt particles are evenly distributed in the fired film (silver decorative portion) of the composition. Therefore, according to the above-mentioned configuration, it is possible to provide a decorative composition that realizes a silver decorative portion with excellent color development and luster.

[0008] In a preferred embodiment of the decorative composition disclosed herein, the ratio of the combined molar fraction of the second element and the third element to the molar fraction of the first element ((second element + third element) / first element) is 0.1 or greater and 1 or less. According to this configuration, a decorative composition is provided that realizes a silver decorative portion having more suitable color development and luster.

[0009] In a preferred embodiment of the decorative composition disclosed herein, the Pt content in the above molar ratio is 50 mol % or more and 80 mol % or less. According to this configuration, more suitable color development can be achieved in the silver decorative portion.

[0010] In a preferred embodiment of the decorative composition disclosed herein, the content of Rh in the above molar ratio is 3 mol % or more and 10 mol % or less. According to this configuration, the effects of the technology disclosed herein can be exerted more stably.

[0011] In a preferred embodiment of the decorative composition disclosed herein, the Pd content in the above molar ratio is 10 mol % or more and 35 mol % or less. According to this configuration, it is possible to provide a decorative composition that realizes a silver decorative portion having a more suitable luster.

[0012] In a preferred embodiment of the decorative composition disclosed herein, the precious metal element further includes a fourth element, the fourth element being at least one element selected from the group consisting of Au, Ag, Ru, and Os. In another preferred embodiment of the decorative composition disclosed herein, the content of the fourth element in the molar ratio is 18.5 mol% or less. According to this configuration, the effects of the technology disclosed herein can be optimally exhibited, and a silver decorative part with excellent color development and luster can be provided.

[0013] Also, from another aspect, there is provided a ceramic product as disclosed herein. The ceramic product as disclosed herein comprises a ceramic substrate and a silver decorative part arranged on the ceramic substrate and made of a fired body of the decorative composition as disclosed herein. The silver decorative part has an 8° gloss value of 750 or more when measured by the SCI method, and a lightness L of the silver decorative part when the 8° gloss value is measured by the SCE method. * Divided by (8° gloss value / lightness L * ) is 20 or more. According to this configuration, it is possible to provide a ceramic product having a silver decorative portion with excellent color development and luster. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is an FE-SEM observation image (10,000x) of the silver decorative portion according to Example 1. [Diagram 2] FIG. 2 is an FE-SEM observation image (10,000x) of the silver decorative portion according to Comparative Example 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Preferred embodiments of the technology disclosed herein will be described below. Matters other than those specifically mentioned in this specification that are necessary for implementation (e.g., a method for manufacturing a ceramic substrate to be decorated, etc.) 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 in the relevant field. The content of the technology disclosed herein can be implemented based on the content disclosed in this specification and the technical common sense of the relevant field. In this specification, the expression "A to B" indicating a range means A or more and B or less.

[0016] <Decorative Composition> The decorative composition disclosed herein (hereinafter, sometimes simply referred to as "composition") is used to form a silver decorative part on a ceramic substrate. The decorative composition disclosed herein contains a precious metal element and a matrix-forming element. The precious metal element contains at least Pt, Rh, and at least one of Pd and Ir. The matrix-forming element contains at least Bi. In the molar ratio where the sum of the precious metal element and the matrix-forming element is 100 mol%, the content of the precious metal element is 80 mol% or more, and the sum of Rh, Pd, and Ir is 6 mol% or more and 60 mol% or less. By firing such a decorative composition, a silver decorative part with good color development and gloss can be formed on the ceramic substrate.

[0017] The reason why such an effect is obtained is not particularly limited, but is presumed to be as follows. Platinum (Pt) element is more likely to be oversintered than other precious metal elements such as gold (Au) element and silver (Ag) element, and Pt particles tend to be easily aggregated. When Pt particles are oversintered, unevenness occurs on the surface of the silver decorative part, which can impair gloss. In addition, Pt is a component that particularly contributes to the coloring of the silver decorative part. Therefore, when Pt particles grow excessively in the fired body (silver decorative part) of the decorative composition, or when oversintering occurs, the color development and gloss may decrease in the area where the Pt particles are few. Therefore, in the decorative composition disclosed herein, in addition to the Pt element, Rh is contained as an essential constituent element. In addition to Pt and Rh, either one of Pd and Ir, or both, are contained. According to the inventors' research, it was found that when Rh, Pd, and Ir are fired together with Pt, Rh, Pd, and Ir adhere to the periphery of Pt particles as oxides during firing, suppressing the aggregation of Pt particles. This makes it possible to suppress the Pt particles from becoming coarse due to firing. In addition, since the Pt particles do not aggregate, the Pt particles are evenly distributed in the silver decoration part. This makes it possible to improve the color development and gloss of the silver decoration part.

[0018] As described above, the decorative composition disclosed herein contains at least a precious metal element and a matrix-forming element. Hereinafter, various components that may be contained in the decorative composition disclosed herein will be specifically described.

[0019] The precious metal element is a component that contributes to the coloring of the fired body of the decorative composition (hereinafter, simply referred to as the "silver decorative portion"). Examples of the precious metal element include gold (Au), silver (Ag), platinum (Pt), rhodium (Rh), iridium (Ir), palladium (Pd), ruthenium (Ru), and osmium (Os). The decorative composition disclosed herein contains at least a first element, a second element, and a third element as the precious metal elements. The first element is platinum (Pt). The second element is rhodium (Rh). The third element (third element group) is at least one selected from the group consisting of palladium (Pd) and iridium (Ir). That is, the decorative composition disclosed herein contains Pt and Rh as essential components. The decorative composition disclosed herein also contains, in addition to Pt and Rh, either one of Pd and Ir, or both. This makes it possible to provide a decorative composition that realizes a silver decorative part with good color development and luster. The precious metal element may be contained in the decorative composition, for example, in the form of a metal resinate (a metal organic compound). However, the state of the precious metal element in the decorative composition is not limited to the above-mentioned metal resinate, and may be a complex, a polymer, or metal particles.

[0020] The decorative composition disclosed herein has a content of precious metal elements of at least 80 mol% or more in a molar ratio (hereinafter, simply referred to as "molar ratio of the decorative composition") where the sum of the precious metal elements and the matrix-forming elements contained in the decorative composition is 100 mol%. The content of the precious metal elements is preferably 83 mol% or more, more preferably 84 mol% or more, and may be 90 mol% or more in the molar ratio of the decorative composition. In addition, since the decorative composition disclosed herein contains a matrix-forming element, the content of the precious metal elements in the molar ratio of the decorative composition is preferably 98 mol% or less, more preferably 97 mol% or less, and may be 96 mol% or less. By having the content of the precious metal elements in the above-mentioned range, the proportion of the precious metal components in the decorative composition is sufficiently ensured, and a silver decorative part with good color development and luster can be realized.

[0021] Platinum (Pt) is a component that imparts a lustrous silver-based color tone to the silver decorative part. In addition, Pt is relatively cheaper than Au, Pd, etc., and is advantageous from the viewpoint of cost. The decorative composition disclosed herein contains Pt as an essential component. For example, Pt is preferably contained in the decorative composition as a constituent element of Pt resinate. The content ratio of the Pt element is preferably 35 mol% or more, more preferably 39 mol% or more, and even more preferably 50 mol% or more, in terms of a molar ratio when the total of the precious metal elements and the matrix-forming elements contained in the decorative composition is taken as 100 mol%. This can suitably improve the gloss value (luster) of the silver decorative part. If the content ratio of Pt in the decorative composition is too high, the effect of suppressing over-sintering by Rh, Pd, and Ir is not fully exerted, and the color development and luster of the silver decorative part may be impaired. From this viewpoint, the content of Pt element is, for example, preferably 90 mol % or less, more preferably 85 mol % or less, and even more preferably 80 mol % or less in terms of molar ratio in the decorative composition. The content of each element in the decorative composition can be measured, for example, by ICP emission spectrometry.

[0022] Among the precious metal elements, Pt is a component that exhibits a particularly lustrous silver-based color tone, and by including a large amount of such Pt, a silver decorative part having more suitable color development and luster can be provided. From this viewpoint, it is preferable that Pt is a major component among the precious metal elements contained in the decorative composition (i.e., Pt is 50 mol % or more of the precious metal elements contained in the decorative composition). When the precious metal elements contained in the decorative composition are taken as 100 mol %, Pt is, for example, 50 mol % or more, preferably 57 mol % or more, may be 60 mol % or more, or may be 70 mol % or more. As described above, the decorative composition disclosed herein contains Rh, Pd, Ir, etc. as precious metal elements in addition to Pt from the viewpoint of improving color development and luster. Therefore, when the precious metal elements contained in the decorative composition are taken as 100 mol %, Pt is, for example, preferably 94 mol % or less, more preferably 92.5 mol % or less.

[0023] Rhodium (Rh), palladium (Pd) and iridium (Ir) are components that can favorably suppress the increase in particle size of Pt particles caused by firing and increase the number of Pt particles with a suitable particle size. This improves the strength of the silver decorative part and realizes a silver decorative part with good color development. In particular, Rh favorably suppresses the increase in particle size of Pt particles. For this reason, the decorative composition disclosed herein contains Rh as an essential component. In addition to Pt and Rh, the decorative composition disclosed herein contains Pd and / or Ir.

[0024] In the decorative composition disclosed herein, the total of the second element and the third element (in other words, the total of Rh, Pd, and Ir) is 6 mol% or more and 60 mol% or less in the molar ratio when the total of the precious metal element and the matrix-forming element contained in the decorative composition is 100 mol%. In the molar ratio of the decorative composition, the total of the second element and the third element is preferably 6 mol% or more, more preferably 10 mol% or more, even more preferably 17 mol% or more, and may be 20 mol% or more. This provides the above-mentioned effects, and the color development and gloss of the silver decorative part are suitably improved. Rh, Pd, and Ir tend to have a slightly lower gloss than Pt and to have a dull silver color. In addition, if Rh, Pd, and Ir are contained in the decorative composition in excess, there is a risk that the Pt particles will become excessively small, which may result in an area in the silver decorative part where there are few (or no) Pt particles. For this reason, excessive content of Rh, Pd, and Ir is undesirable from the viewpoint of color development. In addition, since Rh, Pd, and Ir are expensive, it may be disadvantageous from the viewpoint of cost. From these viewpoints, the total of the second element and the third element is preferably 60 mol % or less, more preferably 50 mol % or less, and even more preferably 46 mol % or less, and may be 40 mol % or less, or may be 30 mol % or less.

[0025] The content ratio of each of Rh, Pd, and Ir in the decorative composition is not particularly limited as long as the total of Rh, Pd, and Ir is adjusted to satisfy the above-mentioned range. The content ratio of Rh element is preferably 1 mol% or more, more preferably 2 mol% or more, even more preferably 3 mol% or more, and particularly preferably 3.9 mol% or more in the molar ratio of the decorative composition. If Rh is contained in excess in the decorative composition, there is a risk that the Pt particles will become excessively small. From this viewpoint, the content ratio of Rh element is preferably 10 mol% or less, more preferably 8 mol% or less, and may be 5 mol% or less in the molar ratio of the decorative composition.

[0026] The decorative composition disclosed herein may or may not contain Pd. When the decorative composition contains Pd, the content of Pd element is preferably 1 mol% or more, more preferably 5 mol% or more, even more preferably 10 mol% or more, and particularly preferably 12 mol% or more in the molar ratio of the decorative composition. When Pd is contained in a larger amount than Pt in the decorative composition, the gloss value tends to be lower. From this viewpoint, the content of Pd is preferably 45 mol% or less, more preferably 40 mol% or less, even more preferably 35 mol% or less, and particularly preferably 25 mol% or less in the molar ratio of the decorative composition.

[0027] The decorative composition disclosed herein may or may not contain Ir. When the decorative composition contains Ir, the content of Ir element is preferably 1 mol% or more, more preferably 1.5 mol% or more, and even more preferably 2 mol% or more in the molar ratio of the decorative composition. The content of Ir is preferably 5 mol% or less, more preferably 4 mol% or less, even more preferably 3 mol% or less, and particularly preferably 2.6 mol% or less in the molar ratio of the decorative composition.

[0028] As described above, by including Rh, Pd, and Ir together with Pt, over-sintering of Pt is suitably suppressed, and the color development and gloss of the silver decorative part are improved. For example, by suitably adjusting the molar fraction ratio of Pt to (Rh+Pd+Ir), the above-mentioned effects are more favorably exhibited, and the gloss value of the silver decorative part tends to be further improved. Although not particularly limited, the ratio of the total molar fraction of the second element and the third element to the molar fraction of the first element ((second element+third element) / first element) is preferably 0.08 or more, more preferably 0.1 or more, and particularly preferably 0.3 or more. If the total molar fraction of Rh, Pd, and Ir is too high relative to the molar fraction of Pt, the gloss value of the silver decorative part tends to be low. From this viewpoint, the ratio of the total molar fraction of the second element and the third element to the molar fraction of the first element ((second element + third element) / first element) is preferably 1.2 or less, more preferably 1 or less, and even more preferably 0.5 or less.

[0029] The decorative composition disclosed herein may contain a fourth element as a precious metal element other than the elements mentioned above, specifically, gold (Au), silver (Ag), ruthenium (Ru), and osmium (Os).

[0030] The decorative composition disclosed herein may or may not contain a fourth element. For example, when the decorative composition contains a fourth element, the content of the fourth element is preferably 18.5 mol% or less, may be 16 mol% or less, may be 10 mol% or less, or may be 5 mol% or less in the molar ratio of the decorative composition. Specifically, when the decorative composition contains Au, the content of the Au element is preferably 0.5 mol% or more and 18.5 mol% or less, and more preferably 1 mol% or more and 18.3 mol% or less in the molar ratio of the decorative composition. Furthermore, when the decorative composition contains Ag, the content of the Ag element is preferably 0.5 mol% or more and 16 mol% or less, and more preferably 1 mol% or more and 15.5 mol% or less in the molar ratio of the decorative composition. When the decorative composition contains Au or Ag, the silver color of the silver decoration part is suitably adjusted, and the gloss value tends to be high. However, as described above, Au and Ag are not essential components of the decorative composition disclosed herein, and may not be present in the decorative composition.

[0031] The matrix-forming elements are components that improve the fixation of the silver decorative part to the ceramic substrate. In this specification, the term "matrix-forming elements" refers to a concept that includes metal elements and metalloid elements that can form an amorphous matrix in the oxide state in the fired body (silver decorative part) of the decorative composition. In addition, the term "amorphous matrix" refers to a structure in which the amorphous oxide (oxide with an amorphous structure) of a specific metal element and metalloid element forms a skeleton, and various metal elements (or metalloid elements) exist in the skeleton as oxides or in the form of 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 above-mentioned noble metal elements, there are elements (such as Ag) that can become amorphous oxides in the firing process and form part of the amorphous matrix. However, in this specification, for the sake of convenience, the elements listed as the above noble metal elements are not considered to be matrix forming elements. Similarly to the precious metal elements, the form of the matrix-forming components in the decorative composition is not particularly limited, and may take the form of a metal resinate (an organic metal compound), a complex, a polymer, fine particles (glass frit), or the like.

[0032] The decorative composition disclosed herein contains at least bismuth (Bi) as a matrix forming element. Bi is a component that forms the skeleton of the amorphous matrix after firing and is a component that can improve adhesion to the substrate. By containing such Bi, the adhesion is improved, so that peeling of the silver decoration part when exposed to, for example, an alkaline chemical can be suitably suppressed.

[0033] The content of Bi element is preferably 2.5 mol% or more, more preferably 3 mol% or more, and may be 6 mol% or more, in terms of the molar ratio when the sum of the precious metal element and the matrix-forming element contained in the decorative composition is taken as 100 mol%. This can suitably exhibit the effect of improving adhesion to the substrate. On the other hand, if the content of Bi in the decorative composition is increased too much, the content of the precious metal element decreases relatively, and there is a risk that the color development and gloss of the silver decorative part will be impaired. From this viewpoint, the content of Bi element is, for example, preferably 20 mol% or less, more preferably 15.5 mol% or less, and even more preferably 15.2 mol% or less, in terms of the molar ratio of the decorative composition.

[0034] The decorative composition disclosed herein may contain metal elements or metalloid elements other than Bi as matrix forming elements, as long as the effect of the technology disclosed herein is not impaired. Examples of such other elements include silicon (Si), yttrium (Y), zirconium (Zr), samarium (Sm), calcium (Ca), barium (Ba), chromium (Cr), tin (Sn), etc. When the entire conductive composition is taken as 100 mol%, the content of the other elements may be, for example, 5 mol% or less, 3 mol% or less, or 1.6 mol% or less, or the other elements may not be included.

[0035] The elements that may be contained in the decorative composition disclosed herein have been described above. In addition to the above-mentioned components, it is preferable that the decorative composition disclosed herein contains various components in consideration of the fixation to the surface of the substrate and the moldability of the silver decorative part. Hereinafter, other components that may be contained in the decorative composition disclosed herein will be described. However, the other components described below can be any conventionally known components that can be used in decorative compositions without any particular restrictions, so long as they do not significantly impede the effects of the technology disclosed herein. In other words, the decorative composition disclosed herein can appropriately change the components other than the above-mentioned essential elements depending on its application.

[0036] First, as described above, the decorative composition disclosed herein may contain both the precious metal element and the 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. The organic compound may be any conventionally known resin material that can be used to produce a metal resinate, without any particular limitations. 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, linoleic acid, and neodecanoic acid; sulfonic acids; resin acids contained in rosin; resin sulfurized balsams containing essential oil components such as turpentine oil and lavender oil, alkyl mercaptides (alkylthiolates), aryl mercaptides (arylthiolates), mercaptocarboxylic acid esters, and alkoxides.

[0037] In addition, in a decorative composition containing a precious metal element and a matrix-forming element in the form of a metal resinate, it is preferable to use an organic solvent that disperses or dissolves the metal resinate. As such an organic solvent, those that have been used in resinate pastes and those that have been used in liquid gold solutions can be used without any particular restrictions. Examples of the organic solvent 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, for example, and such resinate pastes may be used as they are.

[0038] The weight ratio of the solvent that may be contained in the decorative composition is not particularly limited, since the suitable range varies depending on the application method of the decorative composition, and may be adjusted as appropriate. For example, the content of the solvent in the decorative composition may be approximately 10 wt% to 50 wt%. As an example, when applying by inkjet, the content of the solvent in the decorative composition is preferably, for example, 10 wt% to 50 wt%. As another example, when applying by brush, the content of the solvent in the decorative composition is preferably, for example, 10 wt% to 30 wt%.

[0039] The viscosity of the decorative composition is not particularly limited and may be appropriately adjusted 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 may be appropriately adjusted by the amount of solvent or the addition of resin balsam.

[0040] The decorative composition disclosed herein may additionally contain other components as appropriate, so long as they do not significantly impair the effects of the technology disclosed herein. Examples of additional components include organic binders, protective materials, surfactants, dispersants, thickeners, pH adjusters, preservatives, defoamers, plasticizers, stabilizers, antioxidants, etc.

[0041] The decorative composition disclosed herein can be manufactured, for example, by mixing materials containing desired metal elements in a predetermined ratio so as to contain at least each of the precious metal component and the matrix-forming component. As described above, the form of the precious metal component and the matrix-forming component contained in the decorative composition disclosed herein is not limited to metal resinate, and may be a complex, a polymer, or a fine particle. When the precious metal component and the matrix-forming component are in a form other than metal resinate, it is preferable to appropriately change the above-mentioned solvent and additional components according to the form of the precious metal component and the matrix-forming component. For example, when the precious metal component and the matrix-forming component are contained in a form that is not dissolved 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 the like as an additional component.

[0042] <Ceramics products> Hereinafter, one embodiment of the ceramic product disclosed herein will be described. The ceramic product disclosed herein has a silver decorative part containing a precious metal component. For example, the silver decorative part may be provided on a substrate mainly composed of ceramics. Alternatively, for example, the substrate mainly composed of ceramics may have a coating layer mainly composed of an amorphous material (typically glass) and a silver decorative part. Such a ceramic product can be suitably produced by applying the decorative composition described above on a ceramic substrate and firing it.

[0043] (1) Base material The substrate is a molded body mainly composed of ceramics (for example, a molded body with a ceramic content of 50 mass% or more). Examples of ceramics constituting such a substrate include silica (SiO2), alumina (Al2O3), zirconia (ZrO2), magnesia (MgO), titania (TiO2), ceria (CeO2), and yttria (Y2O3). The thickness, shape, hardness, color, and the like of the substrate can be appropriately changed depending on the application of the ceramic product, and detailed description is omitted since they do not limit the technology disclosed herein. Note that the chemical formula shown in parentheses after the above substance name indicates a representative composition of the substance, and is not intended to limit the composition of the actual ceramic to that of the chemical formula.

[0044] (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 the purpose of protecting the substrate. 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 the substrate. The glaze is a chemical agent containing metal elements and semi-metal elements that become oxides when fired and form an amorphous matrix. This glaze may contain the same elements as those contained in the amorphous region of the silver decoration part, or may contain different elements.

[0045] 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, and conventionally known components that can be used to protect ceramic substrates can be appropriately selected. As an example, the coating layer may contain Si, Al, Fe, Mg, Na, Zn, K, Ca, Sn, etc. These elements may form a matrix in the form of amorphous oxides. That is, the coating layer may form an amorphous matrix containing silicon oxide (SiO2), aluminum oxide (Al2O3), iron oxide (Fe2O3), magnesium oxide (MgO), potassium oxide (Na2O), zinc oxide (ZnO), potassium oxide (K2O), calcium oxide (CaO), tin oxide (SnO2), etc. The abundance ratio of each element in the coating layer does not limit the technology disclosed herein, so a detailed description will be omitted.

[0046] (3) Silver decoration The ceramic product disclosed herein has a silver decorative part. The silver decorative part may be formed on the surface of the above-mentioned substrate or on the surface of the coating layer. The silver decorative part of the ceramic product disclosed herein contains a precious metal component. The precious metal component may contain precious metal particles. For example, the precious metal component may be composed of precious metal particles. Such a silver decorative part has an 8° gloss value of 750 or more when measured by the SCI method, and a lightness L of 750 or more when the 8° gloss value is measured by the CE method. * Divided by (8° gloss value / lightness L * ) is 20 or more. That is, the silver decorative part disclosed herein is a decorative part that has a glossy silver color with good color development.

[0047] The glossiness of the silver decorative part can be evaluated by the 8° gloss value (hereinafter, simply referred to as "8° gloss value") measured by 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 part is. The 8° gloss value can be measured using a spectrophotometer (e.g., CM-700d or CM-600d manufactured by Konica Minolta Sensing Co., Ltd.) designed to approximate a 60° gloss meter based on JIS Z 8741:1997. The SCI (Specular Components Include) method is a measurement method that includes regular reflected light in the measurement.

[0048] In addition, the color development of the silver decoration part is measured by the SCE method. * (Hereafter, simply "Lightness L * ") can be used to evaluate the brightness of a color. L based on 013 * a * b * In the color system, this is a value that indicates the degree of whiteness. * The higher the value, the whiter the color. * Measurements can be made using a spectrophotometer conforming to JIS Z 8722:2009 (for example, the CM-700d or CM-600d manufactured by Konica Minolta Sensing, Inc.). The SCE (Specular Components Exclude) method is a method in which regular reflected light is removed and only diffuse reflected light is measured, and is also called the diffuse reflectance measurement method. With the SCE method, the measured values ​​differ depending on the surface condition even for the same color, and it is possible to obtain measurement results that are close to those obtained when the color is recognized visually.

[0049] The silver-colored decorative portion of a ceramic product can be produced by applying the above-mentioned decorative composition to the surface of a ceramic substrate (or coating layer) and firing it. During this firing, the Pt particles are oversintered in the silver-colored decorative portion, resulting in a low 8° gloss value and a high lightness L * The gloss value is low and the lightness L tends to be too high. *When the silver decorative portion has too high a 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 part based on both of the above indices, it is possible to realize a silver decorative part that is free of cloudiness when visually observed and has a good sense of luster and color development.

[0050] Specifically, the silver decorative portion of the ceramic product disclosed herein has an 8° gloss value of 750 or more, and the 8° gloss value is less than the lightness L * Divided by (8° gloss value / lightness L * ) is 20 or more. The higher the 8° gloss value, the more lustrous the silver tends to be. The 8° gloss value of the silver decorative portion is 750 or more, preferably 800 or more, may be 900 or more, may be 990 or more, or may be 1000 or more. The 8° gloss value is expressed as the lightness L * Divided by (8° gloss value / lightness L * ) The higher this value, the better the silver coloring tends to be. 8° Gloss value / Lightness L * is 20 or more, preferably 24 or more, more preferably 50 or more, may be 60 or more, or may be 70 or more. The 8° gloss value and 8° gloss value / lightness L of the silver decorative part * By satisfying the above-mentioned range, a silver decorative part that has both color development and gloss can be realized.

[0051] Lightness L * is not particularly limited as long as it is adjusted to satisfy the above value. * is, for example, preferably 10 or more, and may be 15 or more. * If the lightness L is too high, the silver tends to be whitish and cloudy. * is preferably 50 or less, more preferably 35 or less, even more preferably 30 or less, and particularly preferably 22 or less. For example, the lightness L * is preferably 10 or more and 22 or less.

[0052] In order for the silver decorative parts to have a good silver color, L based on JIS Z 8781:2013 is required. * 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 green direction, +b is * -b is yellow direction, * indicates the blue direction. * and chromaticity b * The measurement can be performed 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, -5 or more and 5 or less, and more preferably -1 or more and 1 or less. In addition, the chromaticity b * (Hereafter, simply "chromaticity b * "). For example, it is preferable that the value is -10 or more and 10 or less, and more preferably -5 or more and 5 or less.

[0053] Although not particularly limited, the ceramic product disclosed herein has suitable alkali resistance. Specifically, the ceramic product disclosed herein has such alkali resistance that 30% or more of the silver decoration remains even after immersion in boiling (100°C) 0.5 wt% Na2CO3 aqueous solution (about 3 L) for 0.5 hours, rinsing with water, and rubbing 10 times with zircon paper. This makes it possible to realize a ceramic product that can be washed, for example, with an automatic dishwasher using an alkaline detergent.

[0054] The silver decorative part 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 part is not particularly limited, but is preferably 20 nm to 300 nm, and more preferably 50 nm to 150 nm. A silver decorative part having such an average thickness can achieve a good silver color without the color of the ceramic substrate showing through. The average thickness of such a silver decorative part can be appropriately adjusted, for example, by the coating method.

[0055] <Method of manufacturing 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 the one produced by the following production method.

[0056] 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 in which a predetermined ceramic material is mixed. In addition, a substrate with a coating layer can be prepared by applying a glaze to the surface of the substrate after firing and then firing it again. However, such a process is not particularly limited as long as the substrate can be prepared. For example, a substrate prepared separately may be purchased and prepared.

[0057] Next, in the manufacture of the ceramic product disclosed herein, a silver decorative part is formed on the substrate (or coating layer). The formation of this silver decorative part can be performed by applying (applying) the decorative composition described above to the surface of the substrate or coating layer, and then firing at a predetermined temperature. In a preferred example of the firing process in this step, the decorative composition disclosed herein is used for "overglaze painting", which is a process for decorating the substrate with the coating layer after the application of glaze. In overglaze painting, the decorative composition is applied to the surface of the glaze, and then the painting is fired at a medium temperature of about 700°C to 1000°C. The decorative composition disclosed herein can also be used for "underglaze painting", which is a process for decorating a bisque-fired substrate (ceramic substrate). In underglaze painting, the decorative composition is applied to the substrate, and then the painting is fired at a high temperature of about 1200°C to 1400°C. Examples of methods for applying the decorative composition include brush painting, screen printing, and inkjet printing.

[0058] In this manner, a ceramic product having a silver decorative part that is glossy and has good color development can be realized. Also, a decorative composition that can suitably form such a silver decorative part can be realized. As described above, the "ceramic product" includes pottery, porcelain, earthenware, stoneware, glass, etc., and specific products include, for example, tableware, decorative utensils, various tiles, sanitary ware, roofing tiles, bricks, clay pipes, and ceramic pipes. In particular, according to the technology disclosed herein, tableware having a silver decorative part that is glossy, not cloudy, and has good color development can be suitably realized. <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.

[0059] 1. Preparation of the decorative composition In this test, the raw materials of the precious metal elements and the matrix-forming elements were mixed to obtain the composition shown in Table 1. Each value in Table 1 is the content (mol%) of each element when the total of the precious metal elements and the matrix-forming elements contained in the decorative composition is 100 mol%. Specifically, various raw materials were mixed in an ointment jar, and mixed for 2 minutes at a rotation speed of 1800 rpm using a mixer (product name: Rotating and Revolving Awatori Mixer) manufactured by Thinky Corporation. In this way, the decorative compositions of Examples 1 to 10, Comparative Examples 1 and 2, and Reference Example 1 were prepared. The viscosity of the decorative composition was 10 to 15 mPa·s. The raw materials of each element used here are shown below. Pt: Pt resinate (platinum resin sulfide balsam) Rh: Rh resinate (rhodium resin sulfide balsam) Pd: Pd resinate (palladium resin sulfide balsam) Ir: Ir resinate (iridium resin sulfide balsam) Au: Au resinate (gold resin sulfide balsam) Ag: Ag resinate (silver resin sulfate) Bi: Bi resinate (bismuth resinate) Si:Si resinate (silicon resin acid salt) Zr: Zr resinate (zirconium resinate) Sm: Sm resinate (samarium resinate)

[0060] (2) Application of the decorative composition and firing A white porcelain plate (length: 15 mm, width: 15 mm) with a coating layer (glaze) applied to the surface was prepared as a ceramic substrate, and the decorative composition prepared above (any of Examples 1 to 10, Comparative Examples 1 and 2, and Reference Example 1) was applied (coated) to the entire surface of one side of the white porcelain plate. At this time, the silver decorative part after firing was adjusted to be 30 to 200 nm. A spin coater (Opticoat MS-A-150) manufactured by Mikasa Co., Ltd. was used to apply the decorative composition. The spin coater was set to spin conditions of 1000 rpm to 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. As a result, the white porcelain plates of Examples 1 to 10, Comparative Examples 1 and 2, and Reference Example 1 with the silver decorative part formed on the surface of the ceramic substrate were obtained.

[0061] (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. The 8° gloss value and lightness L * From, 8° gloss value / lightness L * The 8° gloss value was calculated as 750 or more and the 8° gloss value / lightness L * Silver decorative parts with a score of 20 or more were evaluated as having good luster and color development. The results are shown in Table 1.

[0062] (4) FESEM observation FE-SEM observation was performed on the white porcelain plate on which the silver decoration was formed. Using an FE-SEM (SU8230 manufactured by Hitachi High-Technologies Corporation), an FE-SEM observation image (magnification: 10,000 times) of the surface of the silver decoration was obtained. The acceleration voltage for obtaining the FE-SEM observation image was 10.0 kV, and the emission current was 10±0.5 μA. As an example, the FE-SEM observation images of Example 1 and Comparative Example 2 are shown in FIG. 1 and FIG. 2.

[0063] [Table 1]

[0064] As shown in Table 1, in Examples 1 to 10 and Reference Example 1, which mainly contains Au, the 8° gloss value is 750 or more and the 8° gloss value / lightness L * It can be seen that the value is 20 or more. The decorative compositions of Examples 1 to 10 contain Pt, and the total of Rh, Pd, and Ir is 6 mol% or more and 60 mol% or less in a molar ratio where the total of the precious metal elements and the matrix-forming elements is 100 mol%, so that it is presumed that the effect of suppressing over-sintering of Pt is suitably exhibited, and coloring and gloss are improved. In other words, by using the decorative composition disclosed herein, it is possible to realize coloring and gloss that are equal to or greater than those of a silver decorative part using a composition mainly composed of Au.

[0065] On the other hand, as shown in Table 1, in Comparative Example 1 which does not contain Rh, Pd, or Ir, and in Comparative Example 2 in which the total of Rh, Pd, and Ir exceeds 60 mol %, the 8° gloss value and the 8° gloss value / lightness L * It can be seen that the value is significantly lower. This is presumably because Comparative Example 1, which does not contain Rh, Pd, or Ir, does not exhibit the effect of suppressing Pt oversintering. Also, in Comparative Example 2, in which the total of Rh, Pd, and Ir exceeds 60 mol %, it is presumed that the Pt particles become excessively small and the color-developing elements of Rh, Pd, and Ir themselves become large.

[0066] As shown in Table 1, when the ratio of the total molar fraction of the second and third elements to the molar fraction of the first element ((second element + third element) / first element) is 0.1 or more and 1 or less, the 8° gloss value is 900 or more and the 8° gloss value / lightness L* is 59 or more. In other words, by appropriately adjusting the total molar fraction of Rh, Pd and Ir relative to the molar fraction of Pt, a silver decorative part with even better color development and luster can be realized.

[0067] Although 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.

[0068] The technology disclosed herein includes the following items 1 to 8. The following items 1 to 8 are not limited to the above-described embodiment.

[0069] Item 1 relates to a decorative composition. The decorative composition in item 1 comprises: A decorative composition for use in silver decoration of a ceramic substrate, comprising: Contains a precious metal element and a matrix-forming element, The noble metal element is A first element consisting of Pt; A second element consisting of Rh; A third element which is at least one selected from the group consisting of Pd and Ir; Including, The matrix forming element includes Bi, Here, in the molar ratio where the sum of the noble metal element and the matrix-forming element is 100 mol %, The content of the precious metal element is 80 mol % or more, The total content of the second element and the third element is 6 mol % or more and 60 mol % or less.

[0070] Item 2 is the decorative composition according to item 1, The ratio of the total molar fraction of the second element and the third element to the molar fraction of the first element ((second element+third element) / first element) is 0.1 or more and 1 or less.

[0071] Item 3 is the decorative composition according to item 2, In the above molar ratio, the content of Pt is 50 mol % or more and 80 mol % or less.

[0072] Item 4 is the decorative composition according to any one of items 1 to 3, In the above molar ratio, the content of Rh is 3 mol % or more and 10 mol % or less.

[0073] Item 5 is the decorative composition according to any one of items 1 to 4, In the above molar ratio, the content of Pd is 10 mol % or more and 35 mol % or less.

[0074] Item 6 is the decorative composition according to any one of items 1 to 5, The precious metal element further includes a fourth element, The fourth element is at least one element selected from the group consisting of Au, Ag, Ru, and Os.

[0075] Item 7 is the decorative composition according to any one of items 1 to 6, In the above molar ratio, the content of the fourth element is 18.5 mol % or less.

[0076] Item 8 is about ceramic products. The ceramic products in item 8 are: A ceramic substrate; A silver decorative part is disposed on the ceramic substrate and is made of a fired body of the decorative composition according to any one of items 1 to 7. The silver decorative part has an 8 ° gloss value of 750 or more when measured by the SCI method, and The lightness L of the silver decorative part when the 8° gloss value is measured by the SCE method* Divided by (8° gloss value / lightness L * ) is 20 or more.

Claims

1. A decorative composition for use in silver decoration of a ceramic substrate, comprising: Contains a precious metal element and a matrix-forming element, The noble metal element is A first element consisting of Pt; A second element consisting of Rh; a third element which is at least one selected from the group consisting of Pd and Ir; Including, The matrix forming element includes Bi, Here, in the molar ratio where the sum of the noble metal element and the matrix-forming element is 100 mol %, The content of the precious metal element is 80 mol % or more, A decorative composition, wherein the sum of the second element and the third element is 6 mol % or more and 60 mol % or less.

2. 2. The decorative composition according to claim 1, wherein the ratio of the total molar fraction of the second element and the third element to the molar fraction of the first element ((second element + third element) / first element) is 0.1 or more and 1 or less.

3. 3. The decorative composition according to claim 2, wherein the Pt content in said molar ratio is 50 mol % or more and 80 mol % or less.

4. 3. The decorative composition according to claim 1, wherein the content of Rh in said molar ratio is 3 mol % or more and 10 mol % or less.

5. 3. The decorative composition according to claim 1, wherein the molar ratio of Pd is from 10 mol % to 35 mol %.

6. The noble metal element further includes a fourth element, 3. The decorative composition according to claim 1, wherein the fourth element is at least one element selected from the group consisting of Au, Ag, Ru and Os.

7. 7. The decorative composition according to claim 6, wherein the content of the fourth element in the molar ratio is 18.5 mol % or less.

8. A ceramic substrate; A silver decorative part is disposed on the ceramic substrate and is made of a fired body of the decorative composition according to claim 1 or 2. The silver decorative part has an 8° gloss value of 750 or more when measured by the SCI method, and The lightness L of the silver decorative part when the 8° gloss value is measured by the SCE method ＊ The value divided by (8° gloss value / lightness L ＊ ) is 20 or more.

Images