Invisible anti-counterfeiting ceramic ink, ceramic tile and preparation method thereof

Abstract

The present invention belongs to the technical field of ceramic inks, and specifically discloses an invisible anti-counterfeiting ceramic ink, a ceramic tile, and a preparation method thereof. The raw material components of the invisible anti-counterfeiting ceramic ink include europium azelaic acid, a composite solvent, and a defoaming agent, wherein the composite solvent includes n-pentane and dimethylhexane. The present invention utilizes the penetration characteristics of independently synthesized europium azelaic acid, and combines it with specific composite solvents n-pentane and dimethylhexane, as well as a defoaming agent, to vertically penetrate the rare earth europium element with photosensitive properties to a certain depth below the surface of the ceramic tile. After high-temperature firing, europium oxide with luminescence at a specific excitation wavelength is formed, which not only prevents the blurring of the ceramic tile pattern caused by the horizontal diffusion of the ink, but also retains a complete invisible anti-counterfeiting code mark in the ceramic tile after polishing.

Description

Technical Field

[0001] The present invention belongs to the technical field of ceramic inks, and in particular relates to invisible anti-counterfeiting ceramic ink, ceramic tiles and a preparation method thereof. Background Art

[0002] With the application of ceramic inkjet printing decoration technology, ceramic tiles have become more homogenized, leading to frequent incidents of trademark counterfeiting and mixed goods. Applying invisible anti-counterfeiting codes on ceramic tiles can effectively solve this problem.

[0003] Currently, the invisible anti-counterfeiting codes on existing invisible anti-counterfeiting ceramic tiles are only applicable to two-dimensional surfaces, which only addresses the invisible anti-counterfeiting issues of non-polished ceramic tiles. For ceramic tiles with three-dimensional decorations, the textured patterns on the surface require a certain thickness of polishing. During this process, most of the material that provides the invisible anti-counterfeiting function is polished away, and the invisible function is also lost.

[0004] In view of the three-dimensional polished products, the existing invisible anti-counterfeiting ink cannot meet the process requirements of this type of ceramic tile products, and there is an urgent need to develop an invisible anti-counterfeiting ceramic ink with a certain penetration depth. Summary of the Invention

[0005] The present invention aims to address at least one of the technical problems existing in the aforementioned prior art. To this end, the present invention provides an invisible anti-counterfeiting ceramic ink, a ceramic tile, and a method for preparing the same. The ceramic ink exhibits excellent vertical penetration characteristics, preventing the deterioration of the tile pattern caused by horizontal diffusion of the ink. Furthermore, after polishing, the ceramic tile retains its intact invisible anti-counterfeiting code.

[0006] In order to solve the above technical problems, the first aspect of the present invention provides an invisible anti-counterfeiting ceramic ink, wherein the raw material components of the invisible anti-counterfeiting ceramic ink include europium azelaic acid, a composite solvent and a defoaming agent, wherein the composite solvent includes n-pentane and dimethylhexane;

[0007] The preparation process of europium azelaate comprises the following steps:

[0008] (1) adding europium oxide and water into a sand mill and grinding them to obtain europium hydroxide slurry;

[0009] (2) adding azelaic acid to the europium oxyoxide slurry prepared in step (1), heating, adjusting the pH value, and stirring to obtain a mixed solution containing europium azelaate;

[0010] (3) The mixed solution obtained in step (2) is allowed to stand for stratification, and the lower aqueous phase is separated to obtain the upper organic phase, i.e., the europium azelaic acid.

[0011] The present invention utilizes the penetration characteristics of independently synthesized europium azelaic acid, combined with a specific composite solvent and a defoaming agent, to vertically penetrate the rare earth europium element with photosensitive properties to a certain depth below the surface of the ceramic tile. After high-temperature firing, europium oxide with luminescence at a specific excitation wavelength is formed. This not only prevents the influence of the ceramic tile pattern caused by the horizontal diffusion of ink, but also after polishing and grinding, the complete invisible anti-counterfeiting code logo can still be retained in the ceramic tile.

[0012] Research has found that europium azelaic acid, a linear dicarboxylate containing nine carbon atoms, can completely dissolve in organic solvents at room temperature to form a permeable solution. Furthermore, europium azelaic acid has a high density and tends to penetrate vertically downward under gravity. Furthermore, the molecular chain of azelaic acid contains two carboxylic acids, which can react and bind to more europium ions, facilitating the enrichment of the ink's active ingredients. Therefore, adding a certain amount of europium azelaic acid to ceramic ink allows it to vertically penetrate to a depth of 0.2-0.4 mm below the surface of the ceramic tile, without affecting the pattern effect of the ceramic tile product due to horizontal diffusion of the ink. Furthermore, during the high-temperature firing process of ceramic tiles, the organic elements of europium azelaic acid are burned away, and the europium azelaic acid is oxidized to form europium oxide. Because the rare earth element europium in europium oxide has an unfilled 4f electron shell, shielded by the outer 5s and 5p electrons, the 4f electrons in the rare earth element europium oxide undergo a transient luminescence phenomenon when excited by external energy (such as specific light waves). This luminescence disappears immediately when the external energy is removed, making it suitable for use as an anti-counterfeiting marking material for ceramic tiles. Furthermore, after high-temperature firing, europium oxide exhibits no color under visible light, thus maintaining its invisible properties and maintaining the decorative effect of the ceramic tile.

[0013] The present invention also uses n-pentane and dimethylhexane as a composite solvent. Both n-pentane and dimethylhexane contain five and six carbon atoms in their molecular structures, respectively, and are short-chain alkanes with low viscosity. Furthermore, n-pentane has a relatively low boiling point (36°C), while dimethylhexane has a relatively high boiling point (90°C). The combination of these two low-viscosity solvents with different boiling points further promotes the vertical downward penetration of europium azelaate.

[0014] Furthermore, azelaic acid is a polycarbonate with very weak acidity, and its reaction rate with europium oxide is extremely slow, or even non-reactive. The present invention first ultrafinely grinds europium oxide powder using a sand mill, and then mechanochemically activates the reaction to promote the hydrolysis of europium oxide to form europium hydroxide. Then, under certain temperature and pH conditions, the europium hydroxide reacts with azelaic acid to produce europium azelate.

[0015] In some embodiments of the present invention, in step (1), the grinding process parameters are: using zirconia ceramic microbeads with a particle size of 0.3-0.5 mm as the grinding medium, the filling rate of the grinding medium is 75-85%, and the grinding is carried out for 1-2 hours at a rotation speed of 1500-2000 rpm.

[0016] In some embodiments of the present invention, in step (2), the heating temperature is 60-80° C., and the pH value is 6.5-7.0.

[0017] In some embodiments of the present invention, the molar ratio of europium oxide to azelaic acid is 1:(2-2.2).

[0018] In some embodiments of the present invention, the defoaming agent is geranyl acetate.

[0019] Specifically, geranyl acetate, with the chemical formula trans-3,7-dimethyl-2,6-octadien-1-ol acetate, has low surface tension. The diene double bond in its molecular structure increases the molecule's polarity. Furthermore, the intermolecular interaction between diene double bonds is weaker than that of alkanes or alkenes, which helps reduce the surface tension of bubble wrap, accelerating bubble rupture and achieving rapid defoaming. This helps protect the integrity of invisible security codes and makes them recognizable. Furthermore, geranyl acetate does not negatively affect the luminescence of europium oxide.

[0020] In some embodiments of the present invention, the raw material components of the invisible anti-counterfeiting ceramic ink include, by weight: 10-15 parts of europium azelaic acid, 30-40 parts of n-pentane, 25-35 parts of dimethylhexane, and 3-8 parts of defoaming agent.

[0021] In some embodiments of the present invention, in the invisible anti-counterfeiting ceramic ink, the content of europium ions is 2-3 wt %.

[0022] In some embodiments of the present invention, the invisible anti-counterfeiting ceramic ink has a viscosity of 15-30 mPa·s at room temperature and a specific gravity of 0.7-0.9 g·cm -3 .

[0023] A second aspect of the present invention provides a method for preparing the invisible anti-counterfeiting ceramic ink, comprising the following steps:

[0024] Europium azelaic acid and a defoaming agent are added to a composite solvent, stirred, allowed to stand for aging, and filtered to obtain the invisible anti-counterfeiting ceramic ink.

[0025] In some embodiments of the present invention, the static aging time is 10-15 hours.

[0026] In some embodiments of the present invention, the pore size of the filter element used for the filtration is 500-700 nm.

[0027] A third aspect of the present invention provides an invisible anti-counterfeiting ceramic tile, which includes a body and an invisible anti-counterfeiting code. The invisible anti-counterfeiting code is formed by inkjet printing the invisible anti-counterfeiting ceramic ink on the surface of the body and then firing.

[0028] In some embodiments of the present invention, the invisible anti-counterfeiting code emits light with an excitation wavelength of 254-395 nm.

[0029] Specifically, the excitation wavelengths of luminescence from different rare earth oxides vary. Currently, UV lamps on the market have fixed wavelengths of 254nm, 275nm, 365nm, and 395nm. Research has found that europium oxide exhibits transient luminescence under UV light of these wavelengths, while other single rare earth metal oxides do not emit luminescence under these wavelengths.

[0030] A fourth aspect of the present invention provides a method for preparing the invisible anti-counterfeiting ceramic tile, comprising the following steps:

[0031] The invisible anti-counterfeiting code is inkjet printed on the surface of the green body, and the green body is dried, fired and surface polished to obtain the invisible anti-counterfeiting ceramic tile.

[0032] Specifically, since the invisible anti-counterfeiting code has the characteristic of vertical downward penetration, after polishing, the invisible anti-counterfeiting code mark can still be retained intact and will not have a negative impact on the pattern of the ceramic tile.

[0033] Compared with the prior art, the above technical solution of the present invention has at least the following technical effects or advantages:

[0034] (1) The present invention utilizes the penetration characteristics of independently synthesized europium azelaic acid, combined with a specific composite solvent (n-pentane and dimethylhexane) and a defoaming agent, to vertically penetrate the rare earth europium element with photosensitive properties to a certain depth below the surface of the ceramic tile. After high-temperature firing, europium oxide with luminescence at a specific excitation wavelength is formed. This not only prevents the influence on the ceramic tile pattern caused by the horizontal diffusion of ink; but also retains the complete invisible anti-counterfeiting code mark in the ceramic tile after polishing.

[0035] (2) The present invention adopts a pure liquid ceramic ink formula containing rare earth ions, and achieves a deeper vertical penetration effect by combining long-chain carboxylate europium azelaic acid and short-chain low-viscosity composite alkane solvents with high and low boiling points; and utilizes the transient luminescence characteristics of europium oxide under the excitation of a specific ultraviolet light wavelength to achieve invisible anti-counterfeiting of ceramic ink in three-dimensional space.

[0036] (3) In the preparation process of the europium azelaic acid of the present invention, europium oxide is used as a raw material, and a mechanochemical activation reaction is performed to promote the hydrolysis of europium oxide to form hydroxide, which provides the necessary conditions for the subsequent synthesis of europium azelaic acid and provides a simple and easy industrial preparation method for the synthesis of europium azelaic acid. DETAILED DESCRIPTION

[0037] The present invention is described in detail below with reference to the examples to facilitate understanding of the present invention by those skilled in the art. It is necessary to point out that the examples are only used to further illustrate the present invention and are not to be construed as limiting the scope of protection of the present invention. Non-essential improvements and adjustments made to the present invention by those skilled in the art based on the above-mentioned invention should still fall within the scope of protection of the present invention. At the same time, the raw materials mentioned below that are not described in detail are all commercially available products; the process steps or preparation methods that are not mentioned in detail are all process steps or preparation methods known to those skilled in the art.

[0038] Example 1

[0039] Disclosed is an invisible anti-counterfeiting ceramic ink, whose raw material components, measured by weight, include: 10 parts of europium azelaic acid, 30 parts of n-pentane, 25 parts of dimethylhexane, and 3 parts of geranyl acetate; the content of europium ions in the invisible anti-counterfeiting ceramic ink is 2 wt%.

[0040] The method for preparing the invisible anti-counterfeiting ceramic ink comprises the following steps:

[0041] (1) Europium oxide powder was added to pure water (the mass ratio of europium oxide powder to water was 1:2) and stirred to form a slurry; the slurry was then poured into a sand mill for ultrafine grinding reaction, wherein the grinding medium was zirconium oxide ceramic microbeads with a particle size of 0.5 mm and the grinding medium filling rate was 85%; the rotation speed was 1500 rpm and the grinding time was 1 hour to obtain europium hydroxide slurry.

[0042] (2) Azelaic acid (the molar ratio of europium oxide powder to azelaic acid is 1:2) is added to the europium hydroxide slurry prepared in step (1), the temperature is controlled at 80°C, the pH value is 6.5, and stirring is continued to obtain a mixed solution containing europium azelaic acid.

[0043] (3) The mixed solution obtained in step (2) is allowed to stand for separation, wherein the upper layer is an organic phase of europium azelaic acid, and the lower layer is an aqueous phase. The aqueous phase is separated to obtain an upper organic phase, i.e., europium azelaic acid.

[0044] (4) Stir n-pentane and dimethylhexane to obtain a composite solvent; then add europium azelaate and geranyl acetate to the composite solvent, continue stirring, and let it stand for 12 hours; then filter it with a filter element with a pore size of 600 nm to obtain a viscosity of 23 mPa·s and a specific gravity of 0.74 g·cm at room temperature.-3 Invisible anti-counterfeiting ceramic ink.

[0045] Example 2

[0046] Disclosed is an invisible anti-counterfeiting ceramic ink, whose raw material components, measured by weight, include: 15 parts of europium azelaic acid, 35 parts of n-pentane, 28 parts of dimethylhexane, and 8 parts of geranyl acetate; the content of europium ions in the invisible anti-counterfeiting ceramic ink is 2.5wt%.

[0047] The method for preparing the invisible anti-counterfeiting ceramic ink comprises the following steps:

[0048] (1) Europium oxide powder was added to pure water (the mass ratio of europium oxide powder to water was 1:2) and stirred to form a slurry; the slurry was then poured into a sand mill for ultrafine grinding reaction, wherein the grinding medium was zirconium oxide ceramic microbeads with a particle size of 0.3 mm and the grinding medium filling rate was 75%; the rotation speed was 2000 rpm and the grinding time was 1.5 hours to obtain europium hydroxide slurry.

[0049] (2) Azelaic acid (the molar ratio of europium oxide powder to azelaic acid is 1:2) is added to the europium hydroxide slurry prepared in step (1), the temperature is controlled at 60°C, the pH value is 6.8, and stirring is continued to obtain a mixed solution containing europium azelaic acid.

[0050] (3) The mixed solution obtained in step (2) is allowed to stand for separation, wherein the upper layer is an organic phase of europium azelaic acid, and the lower layer is an aqueous phase. The aqueous phase is separated to obtain an upper organic phase, i.e., europium azelaic acid.

[0051] (4) Stir n-pentane and dimethylhexane to obtain a composite solvent; then add europium azelaate and geranyl acetate to the composite solvent, continue stirring, and let it stand for 12 hours; then filter it with a filter element with a pore size of 600 nm to obtain a viscosity of 15 mPa·s and a specific gravity of 0.85 g·cm at room temperature. -3 Invisible anti-counterfeiting ceramic ink.

[0052] Example 3

[0053] Disclosed is an invisible anti-counterfeiting ceramic ink, whose raw material components, measured by weight, include: 12 parts of europium azelaic acid, 36 parts of n-pentane, 35 parts of dimethylhexane, and 7 parts of geranyl acetate; the content of europium ions in the invisible anti-counterfeiting ceramic ink is 2.6wt%.

[0054] The method for preparing the invisible anti-counterfeiting ceramic ink comprises the following steps:

[0055] (1) Europium oxide powder was added to pure water (the mass ratio of europium oxide powder to water was 1:2) and stirred to form a slurry; the slurry was then poured into a sand mill for ultrafine grinding reaction, wherein the grinding medium was zirconium oxide ceramic microbeads with a particle size of 0.5 mm and the grinding medium filling rate was 75%; the rotation speed was 1800 rpm and the grinding time was 1 hour to obtain europium hydroxide slurry.

[0056] (2) Azelaic acid (the molar ratio of europium oxide powder to azelaic acid is 1:2) is added to the europium hydroxide slurry prepared in step (1), the temperature is controlled at 65°C, the pH value is 7.0, and stirring is continued to obtain a mixed solution containing europium azelaic acid.

[0057] (3) The mixed solution obtained in step (2) is allowed to stand for separation, wherein the upper layer is an organic phase of europium azelaic acid, and the lower layer is an aqueous phase. The aqueous phase is separated to obtain an upper organic phase, i.e., europium azelaic acid.

[0058] (4) Stir n-pentane and dimethylhexane to obtain a composite solvent; then add europium azelaate and geranyl acetate to the composite solvent, continue stirring, and let it stand for 12 hours; then filter it with a filter element with a pore size of 600 nm to obtain a viscosity of 24 mPa·s and a specific gravity of 0.78 g·cm at room temperature. -3 Invisible anti-counterfeiting ceramic ink.

[0059] Comparative Example 1

[0060] The difference between Comparative Example 1 and Example 3 is that the raw material components of the invisible anti-counterfeiting ceramic ink are different. Comparative Example 1 uses an equal amount of europium isopentanedioate to replace the europium azelaic acid in Example 3. Accordingly, in step (2) of the preparation method of the invisible anti-counterfeiting ceramic ink, Comparative Example 1 uses an equal amount of isopentanedioic acid to replace the azelaic acid in Example 3.

[0061] Comparative Example 2

[0062] The difference between Comparative Example 2 and Example 3 is that the raw material components of the invisible anti-counterfeiting ceramic ink are different. Comparative Example 2 uses an equal amount of lanthanum azelaic acid to replace the europium azelaic acid in Example 3. Accordingly, in step (1) of the preparation method of the invisible anti-counterfeiting ceramic ink, Comparative Example 2 uses an equal amount of lanthanum oxide powder to replace the europium oxide powder in Example 3.

[0063] Comparative Example 3

[0064] The difference between Comparative Example 3 and Example 3 is that the raw material components of the invisible anti-counterfeiting ceramic ink are different. Comparative Example 3 uses an equal amount of decanane (71 parts by weight) to replace the n-pentane and dimethylhexane in Example 3. Accordingly, in step (4) of the preparation method of the invisible anti-counterfeiting ceramic ink, Comparative Example 3 uses an equal amount of decanane to replace the composite solvent in Example 3.

[0065] Comparative Example 4

[0066] The difference between Comparative Example 4 and Example 3 lies in the different raw material components of the invisible anti-counterfeiting ceramic ink. Comparative Example 4 uses a single n-pentane (71 parts by weight) instead of the n-pentane and dimethylhexane in Example 3. Accordingly, in step (4) of the preparation method of the invisible anti-counterfeiting ceramic ink, the single n-pentane in Comparative Example 4 replaces the composite solvent in Example 3.

[0067] Comparative Example 5

[0068] The difference between Comparative Example 5 and Example 3 is that the raw material components of the invisible anti-counterfeiting ceramic ink are different. Comparative Example 5 uses a single dimethylhexane (71 parts by weight) instead of the n-pentane and dimethylhexane in Example 3. Accordingly, in step (4) of the preparation method of the invisible anti-counterfeiting ceramic ink, the single dimethylhexane in Comparative Example 5 is used instead of the composite solvent in Example 3.

[0069] Comparative Example 6

[0070] The difference between Comparative Example 6 and Example 3 is that the raw material components of the invisible anti-counterfeiting ceramic ink are different. Comparative Example 6 uses an equal amount of dimethyl silicone oil to replace the geranyl acetate in Example 3. Accordingly, in step (4) of the preparation method of the invisible anti-counterfeiting ceramic ink, Comparative Example 6 uses an equal amount of dimethyl silicone oil to replace the geranyl acetate in Example 3.

[0071] Comparative Example 7

[0072] The difference between Comparative Example 7 and Example 3 is that the raw material components of the invisible anti-counterfeiting ceramic ink are different. Comparative Example 7 uses an equal amount of nonylphenol polyoxyethylene ether to replace the geranyl acetate in Example 3. Accordingly, in step (4) of the preparation method of the invisible anti-counterfeiting ceramic ink, Comparative Example 7 uses an equal amount of nonylphenol polyoxyethylene ether to replace the geranyl acetate in Example 3.

[0073] Comparative Example 8

[0074] The difference between Comparative Example 8 and Example 3 is that the preparation method of the ceramic ink is different, and accordingly the raw material components of the prepared ceramic ink are also different.

[0075] The raw material components of the ceramic ink of Comparative Example 8 include, by weight, 12 parts of a mixture of azelaic acid and europium oxide powder (the molar ratio of europium oxide powder to azelaic acid is 1:2), 36 parts of n-pentane, 35 parts of dimethylhexane, and 7 parts of geranyl acetate.

[0076] The method for preparing the ceramic ink comprises the following steps:

[0077] Stir n-pentane and dimethylhexane to obtain a composite solvent; then add azelaic acid, europium oxide powder and geranyl acetate to the composite solvent, continue stirring, and let it stand for 12 hours; then filter with a filter element with a pore size of 600 nm to obtain ceramic ink.

[0078] Application Examples

[0079] The invisible anti-counterfeiting codes were printed by inkjet printing with the ceramic inks prepared in Examples 1-3 and Comparative Examples 1-8 to produce invisible anti-counterfeiting ceramic tiles. The specific steps are as follows:

[0080] The ceramic ink is used to inkjet print an invisible anti-counterfeiting code on the surface of the polished tile body, which is then dried, fired at 1200° C., and polished to 0.15 mm to obtain a ceramic tile.

[0081] Performance Testing

[0082] The ceramic ink samples prepared in Examples 1-3 and Comparative Examples 1-8 were tested for viscosity, defoaming performance, penetration depth in ceramic tiles, and luminescence at room temperature, and horizontal diffusion was recorded. The defoaming performance was evaluated by shaking the ceramic ink for 30 seconds to form bubbles; then, allowing the ink to stand, visually observing the time it took for the bubbles to completely disappear. The luminescence performance was evaluated by irradiating the ceramic tiles prepared in the corresponding examples with UV light at four wavelengths (254nm, 275nm, 365nm, and 395nm). The security code was identified when it was complete and clear. The results are shown in Table 1.

[0083] Table 1:

[0084]

[0085] As shown in Table 1, the invisible anti-counterfeiting ceramic inks prepared in Examples 1-3 of the present invention have a penetration depth of 0.3-0.4 mm, are not affected by polishing, and the invisible anti-counterfeiting codes can be identified; and the ink has no horizontal diffusion and will not affect the pattern of the product.

[0086] Compared with Example 3, Comparative Example 1 uses short-chain isopentanedioic acid instead of long-chain azelaic acid, which causes the ink to diffuse horizontally, which will have an adverse effect on the pattern of the product; at the same time, due to the shallow penetration depth of the short chain, the invisible anti-counterfeiting code is discarded and cannot be identified.

[0087] Comparative Example 2 is different from Example 3. Since rare earth lanthanum oxide is used instead of europium oxide, the four existing ultraviolet lamp wavelengths cannot excite it, so the invisible anti-counterfeiting code cannot be recognized.

[0088] Compared with Example 3, Comparative Example 3 uses long-chain decanane as a solvent, which results in a higher viscosity of the ink, making it difficult to remove bubbles and affecting the penetration depth, causing the invisible anti-counterfeiting code to be discarded and unable to be identified.

[0089] Comparative Example 4, compared to Example 3, uses n-pentane alone instead of the combined solvent of n-pentane and dimethylhexane. n-pentane has a lower boiling point and is more volatile, resulting in poor ink stability and significant viscosity fluctuations. Furthermore, as the ink viscosity increases, its penetration depth decreases, and horizontal penetration occurs. Consequently, the invisible security code is lost and unrecognizable. Furthermore, the horizontal diffusion of the ink adversely affects the product's design.

[0090] Comparative Example 5, compared to Example 3, uses a single dimethylhexane composite solvent of n-pentane and dimethylhexane. The dimethylhexane has side chains, resulting in slower penetration, which also reduces penetration depth and causes horizontal penetration. Consequently, the invisible security code is lost and unrecognizable, adversely affecting the product's design.

[0091] Comparative Example 6 is different from Example 3. Since dimethyl silicone oil, a traditional ceramic ink defoaming agent, is used instead of geranyl acetate, the defoaming effect of dimethyl silicone oil is poor. In addition, the introduction of silicon easily forms a silicon oxide film wrapped around the surface of europium oxide during the high-temperature firing process, and the invisible anti-counterfeiting code is blurred and cannot be identified.

[0092] In Comparative Example 7, compared with Example 3, since the defoaming agent nonylphenol polyoxyethylene ether is used instead of geranyl acetate, the defoaming rate of nonylphenol polyoxyethylene ether is slow, which makes it difficult to remove bubbles in the ink. In actual application, blank areas appear in the ink droplets due to bubbles, resulting in incomplete invisible anti-counterfeiting code and unrecognizable.

[0093] In Comparative Example 8 relative to Example 3, since azelaic acid and europium oxide are directly added to the ink, azelaic acid and europium oxide cannot react effectively, and europium oxide exists in the form of particles, which are filtered out during the ink filtration process, resulting in the presence of basically no europium ions in the ink, and therefore the invisible anti-counterfeiting code cannot be recognized.

[0094] For those skilled in the art to which the present invention belongs, a number of simple deductions or substitutions can be made without departing from the concept of the present invention, without having to resort to creative work. Therefore, based on the disclosure of the present invention, simple improvements made by those skilled in the art to the present invention should be within the scope of protection of the present invention. The above embodiments are preferred embodiments of the present invention, and all processes similar to the present invention and equivalent changes made should fall within the scope of protection of the present invention.

Claims

1. An invisible anti-counterfeiting ceramic ink, characterized in that: The raw material components of the invisible anti-counterfeiting ceramic ink include europium azelaic acid, a composite solvent and a defoaming agent, the composite solvent includes n-pentane and dimethylhexane, and the defoaming agent is geranyl acetate; The preparation process of europium azelaate comprises the following steps: (1) adding europium oxide and water into a sand mill and grinding them to obtain europium hydroxide slurry; (2) adding azelaic acid to the europium hydroxide slurry prepared in step (1), heating, adjusting the pH value, and stirring to obtain a mixed solution containing europium azelaate; (3) The mixed solution obtained in step (2) is allowed to stand for stratification, and the lower aqueous phase is separated to obtain the upper organic phase, i.e., the europium azelaic acid.

2. The invisible anti-counterfeiting ceramic ink according to claim 1, characterized in that: In step (1), the grinding process parameters are: using zirconia ceramic microbeads with a particle size of 0.3-0.5 mm as the grinding medium, the filling rate of the grinding medium is 75-85%, and grinding is performed for 1-2 hours at a rotation speed of 1500-2000 rpm.

3. The invisible anti-counterfeiting ceramic ink according to claim 1, characterized in that: In step (2), the heating temperature is 60-80° C., and the pH value is 6.5-7.

0.

4. The invisible anti-counterfeiting ceramic ink according to claim 1, characterized in that: The molar ratio of europium oxide to azelaic acid is 1:(2-2.2).

5. The invisible anti-counterfeiting ceramic ink according to any one of claims 1 to 4, characterized in that: The raw material components of the invisible anti-counterfeiting ceramic ink include, by weight, 10-15 parts of europium azelaic acid, 30-40 parts of n-pentane, 25-35 parts of dimethylhexane, and 3-8 parts of a defoaming agent.

6. A method for preparing the invisible anti-counterfeiting ceramic ink according to any one of claims 1 to 5, characterized in that: The following steps are involved: Europium azelaic acid and a defoaming agent are added to a composite solvent, stirred, allowed to stand for aging, and filtered to obtain the invisible anti-counterfeiting ceramic ink.

7. An invisible anti-counterfeiting ceramic tile, characterized in that: The invisible anti-counterfeiting ceramic tile comprises a body and an invisible anti-counterfeiting code. The invisible anti-counterfeiting code is formed by inkjet printing the invisible anti-counterfeiting ceramic ink according to any one of claims 1 to 5 on the surface of the body and then firing.

8. The invisible anti-counterfeiting ceramic tile according to claim 7, characterized in that: The invisible anti-counterfeiting code emits light with an excitation wavelength of 254-395 nm.

9. A method for preparing the invisible anti-counterfeiting ceramic tile according to claim 7 or 8, characterized in that: The following steps are involved: The invisible anti-counterfeiting code is inkjet printed on the surface of the green body, and the green body is dried, fired and surface polished to obtain the invisible anti-counterfeiting ceramic tile.

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