Decorative compositions and their uses

Abstract

According to the present disclosure, a technique for obtaining a ceramic product equipped with a decorative film that has adequate chemical resistance and can suppress damage during cleaning is provided. The decorative composition disclosed here includes at least a noble metal element and a glass matrix element. This glass matrix element contains a rare earth element and a first element comprising at least one selected from the group consisting of Si and Al. Also, in the decorative composition disclosed here, the content of the rare earth element in the glass matrix element is 1-45 mol% (inclusive) and the content of the first element in the glass matrix element is 50-90 mol% (inclusive). A decorative film achieving a high level of both alkali resistance and acid resistance can be formed thereby.

Description

[Technical Field]

[0001] The present invention relates to a decorative composition used to decorate ceramic products. Specifically, the decorative composition contains a precious metal element and a glass matrix element. This application claims priority to Japanese Patent Application No. 2021-061345, filed on March 31, 2021, the entire contents of which are incorporated herein by reference. [Background technology]

[0002] Decorative films containing precious metal components are sometimes formed on the surfaces of ceramic products such as porcelain, glassware, and enamelware to impart an elegant or luxurious impression. This type of decorative film is formed by applying a decorative composition containing specific components to the surface of the ceramic product and then firing it. One example of such a decorative composition is a metal resinate (an organic metal compound) containing a precious metal element and a glass matrix element. When such a decorative composition is fired, a decorative film containing a glass region and a precious metal region is formed.

[0003] Incidentally, some ceramic products (e.g., tableware) are expected to be heated in a microwave oven. In this case, if the decorative film on the ceramic product contains a large amount of precious metal regions, high-frequency electromagnetic waves (e.g., a frequency of about 2.45 GHz) may cause sparks and damage the decorative portion. For this reason, microwave-safe decorative compositions with reduced content of precious metal elements have been proposed in recent years. An example of such a microwave-safe decorative composition is disclosed in Patent Document 1. The decorative composition (overglaze paste) described in Patent Document 1 has a precious metal content adjusted to 20% by weight or more and less than 50% by weight, and forms precious metal regions dispersed in a polka dot pattern on the surface of the insulating object (ceramic product) after firing. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent No. 4757434 [Non-patent literature]

[0005] [Non-Patent Document 1] "Study on Rare Earth Silicate Glasses", Research Institute for Inorganic Materials Research Report No. 42, Science and Technology Agency (1985) Summary of the Invention [Problem to be solved by the invention]

[0006] Recently, there has been a demand for the development of technology that can adequately prevent damage (such as peeling or cracking) to decorative films when ceramic products are washed. Specifically, the glass region of the decorative film has poor chemical resistance, and therefore may be damaged when washed in a high-temperature environment using a strong alkaline detergent (for example, in an automatic dishwasher) or when immersed in an acidic detergent for a long period of time. In particular, in microwave-safe ceramic products, the continuity of the precious metal region in the decorative film is lost, making the glass region, which has poor chemical resistance, more likely to be exposed, making the decorative film more susceptible to the above-mentioned damage during washing.

[0007] The present invention has been made in consideration of the above circumstances, and aims to provide a technology for obtaining ceramic products equipped with a decorative film that has sufficient chemical resistance and can suppress damage during cleaning. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems, the present inventors investigated the incorporation of rare earth elements into the glass region of the decorative film after firing. Specifically, it is known that the alkali resistance of glass can be improved by incorporating rare earth elements into the glass matrix (see Non-Patent Document 1). This alkali resistance improvement effect is thought to be due to the tightening of the glass network structure by doping rare earth elements, which have high oxygen affinity, into the glass matrix, thereby inhibiting the penetration of alkali ions. Furthermore, rare earth oxides remain and form a coating even after other components are eluted by exposure to alkaline chemicals, which is thought to also have the effect of inhibiting alkali erosion.

[0009] However, according to the inventors' research, decorative films containing rare earth elements in the glass region have improved alkali resistance but low acid resistance, which can lead to peeling when immersed in acidic detergents for long periods of time. The inventors conducted extensive experiments and research to solve this problem and found that in order to ensure sufficient acid resistance for practical use in decorative films containing rare earth elements in the glass region, the total content of silicon (Si) and aluminum (Al) must exceed a certain value. While not intending to limit the technology disclosed herein, it is speculated that this effect is achieved because the acid resistance of the entire glass matrix is ​​ensured by using acid-resistant (alumino)silicate glass as the main skeleton.

[0010] The technology disclosed herein was developed based on the above findings. First, the technology disclosed herein provides a decorative composition for forming a decorative film on the surface of a ceramic product. This decorative composition contains at least a precious metal element and a glass matrix element. The glass matrix element contains a rare earth element and a first element selected from the group consisting of Si and Al. In the decorative composition disclosed herein, the content of the rare earth element is 1 mol% to 45 mol% when the total number of moles of the glass matrix elements is taken as 100 mol%, and the content of the first element is 50 mol% to 90 mol% when the total number of moles of the glass matrix elements is taken as 100 mol%.

[0011] The decorative composition described above contains a certain amount of rare earth elements, making it possible to form a decorative film with a glass region containing rare earth elements. Furthermore, decorative films containing such rare earth elements have excellent alkali resistance, making it possible to reduce damage during cleaning with alkaline detergents. Additionally, the content of the first element (Si, Al) in this decorative composition is adjusted to 50 mol% or more. This sufficiently improves the acid resistance of the decorative film after firing, making it possible to reduce damage during cleaning with acidic detergents. As described above, the decorative composition disclosed herein can be used to obtain ceramic products with decorative films that have sufficient chemical resistance and are able to reduce damage during cleaning.

[0012] In a preferred embodiment of the decorative composition disclosed herein, the content of precious metal elements is 25 mol% or more and 85 mol% or less, where the total moles of metal elements and metalloid elements contained in the decorative composition is 100 mol%. As mentioned above, decorative films formed from decorative compositions with low content of precious metal elements have the advantage of being less susceptible to breakage when used in a microwave oven, but they also have the problem of being more susceptible to damage during cleaning due to the increased exposure of the glass area. However, the technology disclosed herein improves the chemical resistance of the glass area itself, thereby effectively preventing damage to the decorative film even when the exposed area of ​​the glass area is increased. In other words, the technology disclosed herein is particularly suitable for use in microwave-safe decorative compositions.

[0013] In a preferred embodiment of the decorative composition disclosed herein, the content of the first element is 55 mol % or more and 86 mol % or less when the total number of moles of the glass matrix elements is taken as 100 mol %, which allows the formation of a decorative film that exhibits both high levels of alkali resistance and acid resistance.

[0014] In a preferred embodiment of the decorative composition disclosed herein, the Al content is 0 mol% or more and 80 mol% or less, where the total moles of the first element are 100 mol%. Adding Al interacts with rare earth elements to strengthen the glass structure, further enhancing alkali resistance. On the other hand, Si plays a role in forming the glass skeleton, and if the amount of Si added is relatively small, the glass skeleton itself weakens, resulting in reduced chemical resistance. From this perspective, it is preferable to set the maximum Al content in the first element to 80 mol% or less, ensuring a certain level of Si. This allows for the formation of a decorative film with even better chemical resistance. Meanwhile, experiments conducted by the present inventors have confirmed that a decorative film with sufficient chemical resistance can be formed even when the Al content in the first element is 0 mol% (i.e., when the first element consists solely of Si).

[0015] In a preferred embodiment of the decorative composition disclosed herein, the glass matrix element further contains at least one second element selected from the group consisting of Zr, Ti, and Co. This allows the formation of a decorative film with better chemical resistance. To ensure that the addition of the second element effectively improves chemical resistance, the content of the second element is preferably 1 mol% to 25 mol%, assuming that the total number of moles of the glass matrix element is 100 mol%.

[0016] In a preferred embodiment of the decorative composition disclosed herein, the glass matrix elements further contain Bi. This allows the formation of a decorative film with even better chemical resistance. To ensure that the chemical resistance improvement effect of the addition of Bi is properly achieved, the Bi content is preferably 5 mol% to 15 mol% when the total moles of the glass matrix elements are taken as 100 mol%.

[0017] In a preferred embodiment of the decorative composition disclosed herein, the precious metal element contains at least one element selected from the group consisting of Au, Ag, Pt, Rh, Ir, and Pd. By using these precious metal elements, a decorative film that gives an elegant or luxurious impression can be formed relatively easily. DETAILED DESCRIPTION OF THE INVENTION

[0018] Preferred embodiments of the technology disclosed herein are described below. Matters necessary for implementation other than those specifically mentioned in this specification (e.g., detailed preparation methods for decorative compositions and manufacturing procedures for ceramic products) 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.

[0019] 1. Decorative compositions The decorative composition disclosed herein will be described below. This decorative composition contains at least a noble metal element and a glass matrix element. Each of these elements will be described in detail below.

[0020] (1) Noble metal elements Precious metal elements are components that contribute to the coloring of the fired decorative composition (i.e., decorative film). Specifically, the decorative composition disclosed herein may contain gold (Au), silver (Ag), platinum (Pt), rhodium (Rh), iridium (Ir), palladium (Pd), ruthenium (Ru), and osmium (Os) as precious metal elements. Among these precious metal elements, Au, Ag, Pt, Rh, Ir, and Pd are preferred from the viewpoint of relatively easy formation of a decorative film that gives an elegant or luxurious impression. The precious metal elements may be contained in the decorative composition in the form of, for example, a metal resinate (an organic metal compound). The state of the precious metal elements in the decorative composition is not limited to the metal resinate described above, but may also be a complex, a polymer, or metal particles.

[0021] The content of precious metal elements in the decorative composition is preferably 85 mol% or less, more preferably 80 mol% or less, even more preferably 70 mol% or less, and particularly preferably 60 mol% or less. While decorative films formed using decorative compositions with low precious metal content have the advantage of being less susceptible to breakage when used in a microwave oven, they also have the problem of being more susceptible to damage during cleaning due to increased exposure of the glass surface. However, the technology disclosed herein can effectively prevent damage to decorative films even with decorative compositions with low precious metal content. The lower limit of the precious metal content is preferably 25 mol% or more, more preferably 30 mol% or more, even more preferably 40 mol% or more, and particularly preferably 50 mol% or more. This facilitates the formation of decorative films that impart an elegant or luxurious impression. In this specification, the term "content in the decorative composition" refers to the content (mol%) of a specific element when the total number of moles of metal elements and metalloid elements (i.e., B, Si, As, Te, and At) contained in the decorative composition is taken as 100 mol%.

[0022] (2) Glass matrix elements In this specification, the term "glass matrix elements" encompasses metal and metalloid elements that can form a matrix structure in the glass region of a decorative film after firing. Examples of such glass matrix elements include Al, Ti, Zr, Si, Bi, 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, Ni, In, Co, and Cr. Among the noble metal elements listed above, some elements (e.g., Ag) may be partially oxidized during firing and incorporated into the glass matrix. However, for the sake of simplicity, the elements listed in (1) noble metal elements are not considered glass matrix elements in this specification. In other words, the "total number of moles of glass matrix elements" in this specification refers to the total number of moles of metal elements and metalloid elements that can form the matrix of the glass region, excluding precious metal elements. As with precious metal elements, the form of the glass matrix elements in the decorative composition is not particularly limited, and can take the form of metal resinates, complexes, polymers, fine particles (glass frit), etc.

[0023] The decorative composition disclosed herein contains, as glass matrix elements, a rare earth element and at least one first element selected from the group consisting of Si and Al, with the contents of these rare earth elements and first element adjusted within a predetermined range. This allows the formation of a decorative film that exhibits high levels of both alkali resistance and acid resistance and prevents damage to the decorative film during cleaning. The glass matrix elements of the decorative composition disclosed herein are described in detail below.

[0024] (a) Rare earth elements The rare earth elements can be selected without limitation from the following: 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). These rare earth elements have a high oxygen affinity, so when doped into the glass matrix, they tighten the glass network. Furthermore, the rare earth oxides remain and form a coating even after other components are dissolved by exposure to alkaline agents. This prevents alkali from penetrating into the glass region and damaging the decorative coating. Among the rare earth elements mentioned above, Y, La, Ce, Pr, Nd, Sm, and Dy are preferable because they can more appropriately improve the alkali resistance of the glass region.

[0025] In the decorative composition disclosed herein, the rare earth element content in the glass matrix is ​​adjusted to 1 mol% or more to fully utilize the alkali resistance-improving effect of the rare earth element. This allows for adequate suppression of damage to the decorative film even when exposed to an environment where the decorative film is immersed in a high-temperature, strongly alkaline chemical (e.g., automatic dishwashing). To further improve the alkali resistance of the decorative film, the rare earth element content in the glass matrix is ​​preferably 2 mol% or more, more preferably 3 mol% or more, even more preferably 4.5 mol% or more, and particularly preferably 5 mol% or more, for example, 5.5 mol% or more. On the other hand, increasing the rare earth element content tends to decrease the acid resistance of the decorative film. For this reason, in the decorative composition disclosed herein, the upper limit of the rare earth element content is set to 45 mol% or less to achieve both alkali resistance and acid resistance. From the viewpoint of more suitably suppressing the decrease in acid resistance, the upper limit of the content of the rare earth element is preferably 42.5 mol% or more, more preferably 40 mol% or less, and particularly preferably 37.5 mol% or less. In this specification, the "content in the glass matrix elements" refers to the content ratio (mol%) of a specific element when the total number of moles of the above-mentioned glass matrix elements is taken as 100 mol%.

[0026] (b) First element As described above, the decorative composition disclosed herein contains silicon (Si) and / or aluminum (Al) as the first element of the glass matrix. First, Si becomes silicon oxide (SiO2) after firing and forms the skeleton of the glass matrix. Second, it is presumed that a portion of Al forms a complex oxide with other elements (Si, rare earth elements, secondary elements, etc.), thereby enhancing the chemical resistance of the glass matrix. Furthermore, experiments conducted by the present inventors have confirmed that in order to ensure practically sufficient acid resistance in a decorative film containing rare earth elements in the glass region, the total content of silicon (Si) and aluminum (Al) must exceed a certain value.

[0027] Based on the above findings, the decorative composition disclosed herein adjusts the content of the first element (the total content of Si and Al) in the glass matrix elements to 50 mol% or more. This suppresses the decrease in acid resistance due to the addition of rare earth elements and enables the formation of a decorative film that combines high levels of alkali resistance and acid resistance. From the perspective of forming a decorative film with better acid resistance, the content of the first element is preferably 52 mol% or more, more preferably 53 mol% or more, even more preferably 54 mol% or more, and particularly preferably 55 mol% or more. On the other hand, if the content of the first element is increased too much, the content of the rare earth elements will relatively decrease, making it difficult to form a decorative film with sufficient alkali resistance. From this perspective, the upper limit of the content of the first element in the decorative composition disclosed herein is set to 90 mol% or less. From the viewpoint of forming a fired film with better alkali resistance, the upper limit of the content of the first element is preferably 89 mol% or less, more preferably 88 mol% or less, even more preferably 87 mol% or less, and particularly preferably 86 mol% or less. When the total number of moles of the metal elements and metalloid elements contained in the decorative composition is taken as 100 mol%, the content of the first element is preferably 14.5 mol% to 37 mol%, more preferably 19 mol% to 35 mol%, and particularly preferably 20 mol% to 34 mol%.

[0028] The Al content (Al / (Si+Al)) is preferably 80 mol% or less, more preferably 75 mol% or less, even more preferably 50 mol% or less, and particularly preferably 10 mol% or less, when the total moles of the first element is taken as 100 mol%. By limiting the Al content to a certain level and ensuring the Si content, a glass matrix with a strong skeleton and excellent chemical resistance can be formed. Meanwhile, Al is not an essential element among the first elements of the decorative composition disclosed herein. That is, even if the Al content is 0 mol% when the total moles of the first element is taken as 100 mol% (i.e., the first element is composed only of Si), a decorative film with sufficient acid resistance can be formed as long as the total content of the first element in the glass matrix elements is 50 mol% or more. However, containing both Si and Al as the first element provides higher alkali resistance. This is because the addition of Al interacts with the rare earth elements, making the glass structure more robust. From this viewpoint, the content of Al in the first element is preferably 0.01 mol% or more, more preferably 0.05 mol% or more, and particularly preferably 0.1 mol% or more. When the total number of moles of metal elements and metalloid elements contained in the decorative composition is taken as 100 mol%, the content of Al is preferably 0 mol% to 20 mol%, more preferably 0.2 mol% to 18 mol%, even more preferably 0.2 mol% to 10 mol%, and particularly preferably 0.3 mol% to 4 mol%.

[0029] (c) Second element The decorative composition disclosed herein preferably contains at least one second element selected from zirconium (Zr), titanium (Ti), and cobalt (Co). Oxides of these second elements have been confirmed to further improve the chemical resistance of the decorative film after firing. While not intending to limit the technology disclosed herein, the reason for this effect is presumed to be as follows: First, Zr becomes zirconium oxide (ZrO2) after firing, and Ti becomes titanium oxide (TiO2) after firing. It is presumed that ZrO2 and TiO2 are glass network modifiers that are complexed with the silicate glass skeleton. Furthermore, because ZrO2 and TiO2 have extremely high chemical resistance as individual materials, they remain even after other components are eluted by exposure to alkaline chemicals, forming a coating and contributing to the improved chemical resistance of the decorative film after firing. Meanwhile, Co becomes cobalt oxide (at least one of CoO, Co3O4, and Co2O3) after firing. It is assumed that this cobalt oxide also acts as a glass network modifier, forming a complex with the glass skeleton. By strengthening the adhesion between the precious metal and the glass matrix, the cobalt oxide is expected to contribute to improving the chemical resistance of the decorative film after firing.

[0030] The content of the second element in the glass matrix elements is preferably 1 mol% or more, more preferably 2 mol% or more, even more preferably 3 mol% or more, and particularly preferably 4 mol% or more. This allows the addition of the second element to adequately enhance chemical resistance. On the other hand, if the content of the second element is too high, the content of the rare earth element and the first element will relatively decrease, which may actually reduce the chemical resistance of the decorative film. From this perspective, the upper limit of the content of the second element in the glass matrix elements is preferably 25 mol% or less, more preferably 23 mol% or less, even more preferably 22 mol% or less, and particularly preferably 21 mol% or less. Furthermore, when the total number of moles of the metal element and the metalloid element contained in the decorative composition is taken as 100 mol%, the content of the second element is preferably 0.1 mol% to 12 mol% or less, more preferably 0.5 mol% to 11 mol%, even more preferably 1 mol% to 10.5 mol%, and particularly preferably 2 mol% to 10.5 mol%.

[0031] (d) Bismuth (Bi) The glass matrix element of the decorative composition disclosed herein preferably contains bismuth (Bi). Bi becomes bismuth oxide (Bi2O3) after firing and forms part of the skeleton of the glass matrix. Bi2O3 softens glass, improving adhesion. Furthermore, when the substrate is glass, its diffusion into the substrate enhances adhesion. This improved adhesion can prevent the decorative film from peeling when exposed to alkaline chemicals. To maximize the benefits of adding Bi, the Bi content in the glass matrix is ​​preferably 1 mol% or more, more preferably 3 mol% or more, even more preferably 5 mol% or more, and particularly preferably 6 mol% or more. On the other hand, excessively high Bi content may result in a relative decrease in the content of rare earth elements and the first element, potentially reducing the chemical resistance of the decorative film. From this viewpoint, the upper limit of the Bi content in the glass matrix elements is preferably 15 mol % or less, more preferably 14 mol % or less, further preferably 13 mol % or less, and particularly preferably 12 mol % or less.

[0032] However, if the content of Al, one of the first elements mentioned above, is increased too much, the alkali resistance of the decorative film may be reduced. When it is necessary to form a decorative film containing such a large amount of Al, it is preferable to also add a certain amount of Bi. This compensates for the reduced alkali resistance caused by the large amount of Al, and maintains the chemical resistance of the decorative film within an appropriate range. For example, when the Al content in the glass matrix elements is 50 mol% or more (e.g., 70 mol% or more), it is preferable to set the Bi content in the glass matrix elements to 10 mol% or more. This allows the formation of a decorative film with better chemical resistance.

[0033] The above description does not imply that the decorative composition disclosed herein contains Bi as an essential element. Experiments have confirmed that even when a decorative composition that does not contain Bi is used, a decorative film that has sufficient chemical resistance and can be prevented from being damaged during cleaning can be formed.

[0034] (e) Other elements The decorative composition disclosed herein may contain metal or semimetal elements other than those mentioned above as glass matrix 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, P, Ni, and Cr. From the perspective of chemical resistance of the decorative film, the lower limit of the content of the other elements in the glass matrix is ​​not particularly limited, and may be 0.1 mol% or more, 0.5 mol% or more, 1.0 mol% or more, or 1.5 mol% or more. On the other hand, to prevent a relative decrease in the content of active components (e.g., rare earth elements, first elements) that affect the chemical resistance of the decorative film, the upper limit of the content of the other elements is preferably 3.5 mol% or less, more preferably 3.0 mol% or less, even more preferably 2.5 mol% or less, and particularly preferably 2.0 mol% or less.

[0035] (3) Other ingredients The above describes the precious metal elements and glass matrix 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 factors such as adhesion to the surface of the ceramic product and formability of the decorative film. 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 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 components as appropriate depending on its intended use, etc.

[0036] First, as described above, the decorative composition disclosed herein may contain both a noble metal element and a glass matrix element in the form of a metal resinate. In this case, the decorative composition contains an organic compound for forming the metal resinate. Any conventional resin material known for use in producing metal resinates 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 sulfide 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 decorative compositions containing both the noble metal element and the glass matrix 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 a solvent, those conventionally used in resinate pastes or liquid gold can be used 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, for example, and such resinate pastes may be used as they are.

[0038] The solvent content is not particularly limited and is preferably adjusted appropriately depending on the means used to apply the decorative composition to the surface of the ceramic product. For example, when using inkjet printing, the viscosity of the decorative composition must be kept relatively low (e.g., 70 mPa·s or less). For this reason, in decorative compositions for inkjet printing, the solvent content is preferably adjusted to a range of 50 wt% to 200 wt% when the total weight of the components other than the solvent is taken as 100 wt%. On the other hand, when using brush coating or screen printing, it is preferable to form a decorative film of sufficient thickness with a single application, so it is preferable to adjust the solvent content to a range of approximately 10 wt% to 80 wt% to prepare a decorative composition with a certain degree of viscosity.

[0039] The decorative composition disclosed herein may also contain other additional components as long as the effects of the technology disclosed herein are not significantly impaired. Examples of such additional components include organic binders, protective materials, surfactants, thickeners, pH adjusters, preservatives, antifoaming agents, plasticizers, stabilizers, and antioxidants. When using additional components containing metal elements or metalloid elements in the technology disclosed herein, it is necessary to prepare the decorative composition so that the contents of the rare earth elements and the first element described above are the desired values, taking into account the contents of the elements derived from the additional components.

[0040] As mentioned above, the form of the precious metal element and glass matrix element contained in the decorative composition disclosed herein is not limited to metal resinates, but may also be a complex, polymer, or fine particle. When the precious metal element and glass matrix element 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 element and glass matrix element. For example, when the precious metal element and glass matrix element 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 add a dispersant or other additional component.

[0041] 2.Ceramic products The decorative composition disclosed herein is used to form a decorative film on the surface of a ceramic product. Such a decorative film is formed by applying (applying) the decorative composition to the surface of the ceramic product and then performing a firing treatment under specified conditions. An example of a ceramic product is one in which a glass film derived from a glaze is formed on the surface of a ceramic substrate. When targeting such ceramic products, the decorative composition disclosed herein is used as a paint for "overglaze painting," which forms a decorative film on the surface of the glass film. In this overglaze painting, the decorative composition is applied to the surface of the glass film and then fired at a temperature of approximately 700°C to 1000°C. This allows for the formation of a decorative film on the surface of the ceramic product. The decorative composition disclosed herein can also be used as a paint for "underglaze painting," which directly decorates the surface of a bisque-fired ceramic substrate. In this underglaze painting, the decorative composition is applied to the surface of the ceramic substrate and then fired at a temperature of approximately 1200°C to 1400°C. This allows for the formation of a decorative film on the surface of the ceramic product.

[0042] The thickness of the decorative film on the ceramic product disclosed herein is preferably 30 nm or more and 250 nm or less. Ceramic products with such thin decorative films can be significantly damaged if even a small amount of the decorative film peels off during cleaning. In contrast, the technology disclosed herein can improve the chemical resistance of the decorative film and prevent peeling during cleaning. Therefore, the technology disclosed herein is particularly suitable for producing ceramic products with the above-mentioned thin decorative film.

[0043] [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.

[0044] [First test] 1. Sample Preparation <Preparation of decorative composition> In this test, 38 types of decorative compositions were prepared (Examples 1 to 41) with different contents of precious metal elements and glass matrix elements. The contents of each element in Examples 1 to 41 are shown in Table 1. Note that each value in Table 1 represents the content (mol%) of each element when the total number of moles of metal elements and metalloid elements contained in the decorative composition is taken as 100 mol%. In addition, in preparing the decorative compositions in this test example, various raw materials were mixed in an ointment pot and mixed for 2 minutes at a rotation speed of 1800 rpm using a mixer manufactured by Thinky Corporation (product name: Rotating and Revolution Awatori Rentaro).

[0045] The raw materials for each element contained in the decorative composition of this test example are as follows: Ag: Ag resinate (silver resinate) Au: Au resinate (gold resin sulfide balsam) Pt: Pt resinate (platinum resin sulfide balsam) Rh: Rh resinate (rhodium resin sulfide balsam) Al:Al resinates and aluminum complexes Ti:Ti resinates and titanium complexes Zr: Zr resinates and zirconium complexes Co:Co resinate (cobalt resinate) Si:Si resinate (silicon resin acid salt) Bi: Bi resinate (bismuth resinate) Sm: Sm resinate (samarium resinate) Y: Y resinate (yttrium resinate) La: La resinate (lanthanum resinate) Ce:Ce resinate (cerium resinate) Pr: Pr resinate (praseodymium resinate) Nd:Nd resinate (neodymium resinate) Dy: Dy resinate (dysprosium resinate)

[0046] [Table 1]

[0047] <Ceramic product manufacturing> A white porcelain plate (15 mm long, 15 mm wide) with a glaze applied to its surface was prepared, and a decorative composition was applied (sprayed) to the entire surface of one side of the white porcelain plate. The decorative composition was applied using a spin coater (Opticoat MS-A-150) manufactured by Mikasa Corporation, with spin conditions set at 5000 rpm for 10 seconds. The white porcelain plate with the decorative composition applied was then 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 plate with a decorative film formed on its surface being prepared as a ceramic product test piece. The cross section of the decorative film after firing was observed using a field emission scanning electron microscope (FE-SEM) (SU-8200 manufactured by Hitachi High-Technologies Corporation). The thickness of the decorative film after firing was found to be in the range of 30 nm to 250 nm.

[0048] 2.Evaluation Test <Alkali resistance evaluation> In this test, each specimen was immersed for 30 minutes in a 0.5 wt% Na2CO3 aqueous solution (3 L) that had been heated to 100°C and boiled. After immersion, the specimens were rinsed with water and subjected to a scratch test in which they were rubbed with zircon paper 10 times to observe whether or not damage had occurred to the decorative film. In this test, the immersion time was extended in 30-minute increments, and the maximum immersion time during which 30% or more of the decorative film remained was considered to be the "durability time (h)."

[0049] <Acid resistance evaluation> A 4 wt% aqueous solution of acetic acid was kept at room temperature (23-25°C) and the test specimens were immersed in the acetic acid solution for 24 hours. The test specimens were then removed from the acetic acid solution, rinsed with water, and subjected to a scratch test in which zircon paper was rubbed against the specimen 10 times to observe whether the decorative film had been damaged. In this test, samples with 30% or more of the decorative film remaining were considered to have sufficient acid resistance.

[0050] The results of the evaluation tests for Examples 1 to 41 are shown in Table 2. Table 2 also lists the "rare earth element content," "first element content," "second element content," and "Bi content." These contents are values ​​(mol%) when the total number of moles of the glass matrix elements is taken as 100 mol%. Table 2 also lists the "Al content relative to the total number of moles of the first element (Al / (Si+Al))."

[0051] [Table 2]

[0052] As shown in Table 2, Examples 1 to 39 demonstrated durability of 30 minutes or more in the alkali resistance test and prevented peeling of the decorative film in the acid resistance test. On the other hand, the decorative film formed using the decorative composition of Example 40 peeled off within 30 minutes of the alkali resistance test. Comparing Example 40 with Examples 1 to 39 revealed that adding a certain amount of rare earth element to the decorative composition is necessary to prevent peeling of the decorative film due to alkaline chemicals. Furthermore, the decorative film formed using the decorative composition of Example 41 completely peeled off during the acid resistance test. Comparing Example 41 with Examples 1 to 39 revealed that adding a rare earth element alone to the decorative composition is insufficient to achieve both high levels of alkali resistance and acid resistance in the decorative film; adding 50 mol% or more of the first element (Si, Al) to the total amount of glass matrix elements is necessary.

[0053] [Second test] 1. Sample Preparation <Preparation of decorative composition> In this test, five types of decorative compositions were prepared with different contents of precious metal elements and glass matrix elements (Examples 42 to 46). The composition of each decorative composition is shown in Table 3. In preparing the decorative compositions in this test, similar to the first test described above, various raw materials were mixed in an ointment jar and mixed for 2 minutes at a rotation speed of 1800 rpm using a mixer manufactured by Thinky Corporation (product name: Rotating and Revolution Awatori Rentaro).

[0054] [Table 3]

[0055] <Ceramic product manufacturing> A white porcelain plate (15 mm long, 15 mm wide) with a glaze applied to its surface was prepared, and a decorative composition was applied (sprayed) to the entire surface of one side of the white porcelain plate. The decorative composition was applied using a spin coater (Opticoat MS-A-150) manufactured by Mikasa Corporation, with spin conditions set at 5000 rpm for 10 seconds. The white porcelain plate with the decorative composition applied was then dried on a hot plate at 60°C for 1 hour and then fired at 850°C for 10 minutes. This resulted in the white porcelain plate with a decorative film formed on its surface being prepared as a ceramic product test piece. The cross section of the decorative film after firing was observed using a field emission scanning electron microscope (FE-SEM) (SU-8200 manufactured by Hitachi High-Technologies Corporation). The thickness of the decorative film after firing was found to be in the range of 30 nm to 250 nm.

[0056] 2.Evaluation Test In this test, the alkali resistance and acid resistance were evaluated under the same conditions as in the first test. Specifically, for the alkali resistance test, each specimen was first immersed for 30 minutes in a 0.5 wt% Na2CO3 aqueous solution (3 L) that had been heated to 100°C and boiled. After immersion, the specimens were rinsed with water and subjected to a scratch test in which zircon paper was rubbed against the specimen 10 times to observe whether the decorative film had been damaged. The immersion time was then extended in 30-minute increments, and the maximum immersion time during which at least 30% of the decorative film remained was considered the "durability time (h)." The evaluation results for each specimen (Examples 42 to 46) are shown in Table 4.

[0057] On the other hand, for the acid resistance evaluation, a 4 wt% aqueous solution of acetic acid was first maintained at room temperature (23-25°C) and the test specimens were immersed in the acetic acid solution for 24 hours. The test specimens were then removed from the acetic acid solution, rinsed with water, and subjected to a scratch test in which zircon paper was rubbed against the specimen 10 times to observe whether or not damage had occurred to the decorative film. In this test, samples with 30% or more of the decorative film remaining were deemed to have sufficient acid resistance. The evaluation results for each example (Examples 42 to 46) are shown in Table 4.

[0058] [Table 4]

[0059] As shown in Table 4, decorative films with excellent alkali resistance and acid resistance were formed in all of Examples 42 to 46. This confirmed that even when using a decorative composition that does not contain Bi, such as Example 43, a decorative film with sufficient chemical resistance (alkali resistance and acid resistance) could be formed.

[0060] 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 for forming a decorative film on the surface of a ceramic product, At least a noble metal element and a glass matrix element are included, The glass matrix element is A rare earth element, a first element selected from the group consisting of Si and Al; Contains The content of the rare earth element is 1 mol % or more and 45 mol % or less when the total number of moles of the glass matrix elements is 100 mol %, and A decorative composition, wherein the content of the first element is 50 mol % or more and 90 mol % or less when the total number of moles of the glass matrix elements is 100 mol %.

2. 2. The decorative composition according to claim 1, wherein the content of the noble metal element is 25 mol % or more and 85 mol % or less when the total number of moles of the metal element and the metalloid element contained in the decorative composition is 100 mol %.

3. 3. The decorative composition according to claim 1, wherein the content of said first element is 55 mol % or more and 86 mol % or less when the total number of moles of said glass matrix elements is taken as 100 mol %.

4. 4. The decorative composition according to claim 1, wherein the content of Al is 0 mol % or more and 80 mol % or less when the total number of moles of the first element is taken as 100 mol %.

5. 5. The decorative composition according to claim 1, wherein the glass matrix element further contains a second element, which is at least one element selected from the group consisting of Zr, Ti, and Co.

6. 6. The decorative composition according to claim 5, wherein the content of said second element is 1 mol % or more and 25 mol % or less when the total number of moles of said glass matrix elements is taken as 100 mol %.

7. The decorative composition according to any one of claims 1 to 6, wherein the glass matrix element further contains Bi.

8. 8. The decorative composition according to claim 7, wherein the content of Bi is 5 mol % or more and 15 mol % or less when the total number of moles of the glass matrix elements is taken as 100 mol %.

9. 9. The decorative composition according to claim 1, wherein the noble metal element contains at least one element selected from the group consisting of Au, Ag, Pt, Rh, Ir, and Pd.

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