Magnetic composite antibacterial material, preparation method thereof and preparation method of ceramic plate with antibacterial function

Abstract

The application belongs to the field of building ceramics, and particularly relates to a magnetic composite antibacterial material, a preparation method thereof and a preparation method of a ceramic plate with antibacterial function. The magnetic composite antibacterial material comprises a metal modified doped composite material formed by a variable valence transition metal and a rare earth metal with intrinsic oxygen vacancies and a coating layer coated on the surface of the metal modified doped composite material; wherein the variable valence transition metal is selected from cobalt or iron, the rare earth metal with intrinsic oxygen vacancies is selected from at least one of cerium, gadolinium, samarium and yttrium, and the material of the coating layer is sodium alginate. The application selects specific variable valence transition metals and rare earth metals with intrinsic metal oxygen vacancies to prepare a magnetic composite antibacterial material, greatly improves the catalytic activity of the rare earth metal, and combines the rare earth metal with ceramic glaze, so that the magnetic composite antibacterial material can be directly used for the production of the ceramic plate with antibacterial function with stable and persistent antibacterial effect and without affecting the decorative effect through magnetic field positioning.

Description

Technical Field

[0001] This invention belongs to the field of building ceramics, and specifically relates to a magnetic composite antibacterial material and its preparation method, as well as a method for preparing ceramic plates with antibacterial function. Background Technology

[0002] Ceramics are highly favored by consumers in the field of interior and exterior decoration due to their excellent wear resistance, stain resistance, ease of construction, and rich decorative effects. While the decorative functions of ceramic slabs have become very diverse with the improvement of living standards, their functionality remains relatively lacking.

[0003] Antibacterial function is a hidden yet highly practical feature. Higher requirements are placed on antibacterial properties in ceramic tile-clad or processed surfaces that come into contact with the human body, such as walls, floors, dining tables, stovetops, and kitchen countertops. Currently, methods for preparing antibacterial ceramic tiles include coating and sintering. The sintering method is gaining increasing attention due to its long-lasting and stable antibacterial performance. Patent CN202110352934.1 describes the preparation of antibacterial ceramic tiles by introducing Ulan tea crystal containing various rare earth metal oxides into the glaze, achieving antibacterial rates of over 90% against both Escherichia coli and Staphylococcus aureus. Patent CN202011589352.7 describes the preparation of antibacterial ceramic tiles with far-infrared bactericidal effects by introducing rare earth metal oxides into the surface glaze layer and isolating them with a transparent glaze layer, achieving antibacterial rates of 91%~97% against Escherichia coli and Staphylococcus aureus. Patent CN201911278043.5 describes the preparation of antibacterial ceramics by loading nano zinc oxide onto zirconium phosphate and then combining it with transparent glaze, achieving an antibacterial rate of 99% against Escherichia coli and Staphylococcus aureus.

[0004] Current technological solutions have several shortcomings. Rare earth metal oxides have weak far-infrared light penetration, primarily acting on the contact surface or shallow layers. Their bactericidal effect is heavily dependent on temperature and time, typically requiring temperatures above 50-60°C and maintained for a sufficient duration for effective sterilization, and their effectiveness against heat-resistant bacterial spores is limited. Conventional bactericides such as nano-silver, nano-copper oxide, nano-zinc oxide, and nano-titanium oxide, after being mixed and sintered with ceramic glazes, are covered by a glassy phase, resulting in very limited effective bactericidal sites on the surface, long bactericidal ion release cycles, low content, and poor antibacterial effects. Furthermore, for photocatalytically active materials such as nano-zinc oxide and nano-titanium oxide, the absence of ultraviolet light in typical operating environments prevents activation of catalytic activity to generate free radicals, leading to generally poor antibacterial performance. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a magnetic composite antibacterial material and its preparation method, as well as a method for preparing antibacterial ceramic plates. This invention selects specific transition metals and rare earth metals with intrinsic metal oxygen vacancies for doping to prepare the magnetic composite antibacterial material, significantly enhancing the catalytic activity of the rare earth metals. This material is then combined with ceramic glaze and positioned using a magnetic field, allowing it to be directly used in the production of antibacterial ceramic plates with stable and long-lasting antibacterial effects without compromising decorative appeal.

[0006] In a first aspect, the present invention provides a magnetic composite antibacterial material. The magnetic composite antibacterial material comprises a metal-modified doped composite material formed by a variable-valence transition metal and a rare-earth metal with intrinsic metal oxygen vacancies, and a coating layer covering the surface of the metal-modified doped composite material; wherein the transition metal is selected from cobalt or iron, the rare-earth metal is selected from at least one of cerium, gadolinium, samarium, and yttrium, and the coating layer is made of sodium alginate.

[0007] Secondly, the present invention provides a method for preparing the aforementioned magnetic composite antibacterial material. The preparation method includes:

[0008] (1) Dissolve transition metal salts and rare earth metal salts fully in a solvent, then add a complexing agent, stir the reaction, add a gelling agent, and continue stirring the reaction to obtain a gel-like primary product;

[0009] (2) After drying the primary product, a dry gel-like primary product is obtained. After grinding, sieving and calcining, a powdered metal-modified doped composite material is obtained.

[0010] (3) Disperse the metal-modified doped composite material in a solvent, then add the coating liquid, mix evenly, and obtain the precursor liquid;

[0011] (4) The precursor liquid is atomized into the stirred curing liquid. After the curing reaction, the product is collected, filtered, washed and dried to obtain the magnetic composite antibacterial material.

[0012] In an optional embodiment, the transition metal salt has a variable valence transition metal element, and the rare earth metal salt has a rare earth metal element containing an intrinsic oxygen vacancy.

[0013] In an optional embodiment, in step (1), the transition metal salt is at least one of cobalt nitrate, ferric nitrate, cobalt chloride, ferric chloride or their hydrates; the rare earth metal salt is selected from at least one of cerium nitrate, gadolinium nitrate, samarium nitrate, yttrium nitrate, cerium chloride, gadolinium chloride, samarium chloride, yttrium chloride or their hydrates; preferably, the molar ratio of the transition metal to the rare earth metal is 1:(6~9).

[0014] In optional embodiments, the complexing agent is at least one of citric acid and glacial acetic acid, and the gelling agent is at least one of ethylene glycol and glycerol; preferably, the molar ratio of the total amount of transition metal salt and rare earth metal salt to the complexing agent is 1:(1.0~1.5); more preferably, the amount of gelling agent used is 5~20 mL / 0.1 mol (total metal salt). For example, the amount of gelling agent used is 10 mL / 0.1 mol (total metal salt).

[0015] In an optional embodiment, in step (2), the drying is performed at 60~70℃ for 5~6 h, followed by heating to 100~120℃ and continuing to dry for 10~12 h; the calcination is performed at 300~500℃ for 2~4 h; and the particle size of the powdered doped composite material is 20~200 nm.

[0016] In an optional embodiment, in step (3), the coating solution is an aqueous solution of sodium alginate; preferably, the mass ratio of the metal-modified doped composite material to the sodium alginate in the coating solution is 5~10:1~1.5.

[0017] In an optional embodiment, in step (4), the curing liquid is a calcium chloride aqueous solution with a mass concentration of 2% to 6%.

[0018] Thirdly, the present invention provides a method for preparing a ceramic plate with antibacterial function. The preparation method includes:

[0019] The magnetic composite antibacterial material is added to the ceramic glaze and mixed evenly to obtain a magnetic antibacterial glaze.

[0020] The magnetic antibacterial glaze is applied to the surface of the ceramic blank; during the glazing process, an external magnetic field is applied to control the movement path and / or position of the magnetized composite antibacterial material;

[0021] The ceramic blank with the magnetic antibacterial glaze applied is fired to obtain a ceramic plate with antibacterial function.

[0022] In an optional embodiment, the ceramic blank is an unglazed ceramic blank or a ceramic blank that has not been coated with inkjet printing ink. In an optional embodiment, the ceramic blank is a ceramic blank that has been glazed and / or inkjet printed with ink.

[0023] In an optional embodiment, the mass ratio of the magnetic composite antibacterial material in the magnetic glaze to the ceramic glaze is (1.5~3):100; wherein the specific gravity of the ceramic glaze is 1.65~1.75 g / cm³. 3 Preferably, the magnetic antibacterial glaze is applied by spraying; more preferably, the amount of magnetic antibacterial glaze applied is 700~1100 g / m³. 2 .

[0024] In an optional embodiment, the ceramic glaze is a matte glaze. Preferably, the chemical composition of the matte glaze includes, by mass percentage: SiO2 43%~48%, Al2O3 20%~25%, Fe2O3 0.05%~0.2%, CaO 8%~10%, MgO 1%~3%, K2O 0%~1%, Na2O 4%~6%, P2O5 0.1%~0.5%, ZnO 4%~6%, BaO 0.2%~0.5%, and LOI 9%~11%. More preferably, the chemical composition of the matte glaze includes, by mass percentage: 43%~48% SiO2, 20%~25% Al2O3, 0.05%~0.2% Fe2O3, 8%~10% CaO, 1%~3% MgO, 0.1%~1% K2O, 4%~6% Na2O, 0.1%~0.5% P2O5, 4%~6% ZnO, 0.2%~0.5% BaO, and 9%~11% LOI. The gloss of the matte glaze after firing is 12°~14°.

[0025] In an optional embodiment, the strength of the applied magnetic field is 15,000 to 20,000 Gauss.

[0026] In an optional embodiment, the firing temperature is 1120~1180℃ and the firing time is 40~70 min.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) The present invention preferably uses rare earth metal oxides with intrinsic oxygen vacancies as antibacterial components. By doping with fixed variable valence transition metals, the number of oxygen vacancies and the efficiency of generating active oxygen are significantly increased, thereby greatly improving the antibacterial performance of magnetic composite antibacterial materials.

[0029] (2) The present invention preferably modifies rare earth metals with intrinsic oxygen vacancies. Intrinsic oxygen vacancies are less affected by external environmental conditions and can continuously generate active oxygen under light-free conditions. Active oxygen has high bactericidal efficiency, good effect and high stability.

[0030] (3) The invention preferably modifies rare earth metals with intrinsic oxygen vacancies, and sterilizes and antibacterial by continuously generating active oxygen. This is different from sterilization by precipitating metal ions, because the amount of metal ions precipitated in the glaze layer is very small, the precipitation time is long, and the metal ions interfere with human metabolism.

[0031] (4) The present invention preferably modifies the material with magnetic properties and conforms to the characteristics of intrinsic oxygen vacancy rare earth metal oxides. On the one hand, the magnetic composite antibacterial material is uniformly mixed with the ceramic glaze during high-temperature melting. After cooling, the composite antibacterial ions are uniformly dissolved in the network structure of the glass phase of the glaze, protecting the valence cycle of the metal ions and preventing the glaze from eroding and damaging the antibacterial components. On the other hand, the magnetic composite antibacterial material can move directionally under the action of magnetic force, ensuring enrichment on the glaze surface and increasing the active sites.

[0032] (5) The magnetic composite antibacterial material developed in this invention has excellent effects, a simple process, and good compatibility with existing glazes. It can be directly used in the production of antibacterial ceramic products.

[0033] (6) The magnetic antibacterial composite material prepared by the present invention has almost no effect on the wear resistance, gloss, surface quality and color of the ceramic plate itself. Attached Figure Description

[0034] Figure 1 The illustration shows the colony count in the culture medium after antibacterial testing of the antibacterial ceramic plates prepared in Examples 1 and 2 of this invention.

[0035] Figure 2 The illustration shows the colony count in the culture medium after an antibacterial test of a common ceramic plate prepared in Comparative Example 1 of this invention.

[0036] Figure 3 The illustration shows the colony count in the culture medium after antibacterial testing of the antibacterial ceramic plates prepared in Comparative Examples 2 and 3 of this invention.

[0037] Figure 4 The diagram shows the colony count in the culture medium after an antibacterial test of the ceramic plate with antibacterial function prepared in Comparative Example 4 of this invention.

[0038] Figure 5 This is a rendering of the brick surface in Example 6.

[0039] Figure 6 These are renderings of the brick surface in Example 1 (left) and Example 8 (right). Detailed Implementation

[0040] The present invention is further illustrated by the following embodiments. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the present invention.

[0041] The magnetic composite antibacterial material comprises a metal-modified doped composite material formed by a variable-valence transition metal and a rare earth metal with intrinsic oxygen vacancies, and a coating layer covering the surface of the metal-modified doped composite material; wherein the transition metal is selected from cobalt or iron, and the rare earth metal is selected from at least one of cerium, gadolinium, samarium, and yttrium.

[0042] Cerium oxide (CeO2) has an Fm-3m fluorite structure and can be obtained through Ce. 4+ ↔Ce 3+ Reversible redox reactions naturally generate intrinsic oxygen vacancies (CeO). 2-x Furthermore, during high-temperature sintering with the glaze, it can form a stable solid solution dispersion phase, while still maintaining Ce. 4+ ↔Ce 3+ Equivalent state cycles and oxygen vacancies. Samarium oxide (Sm₂O₃), yttrium oxide (Y₂O₃), and gadolinium oxide (Gd₂O₃) belong to the body-centered cubic La₃ type, and their crystal structure (111 crystal face) has an irregular hexagonal serrated atomic arrangement, naturally forming intrinsic oxygen vacancies. Intrinsic oxygen vacancies are an inherent, periodic arrangement in their crystal structure, which gives them stable and persistent catalytically active sites. Under light-free conditions, these oxygen vacancies can directly adsorb and activate oxygen or water molecules in the air, thereby generating reactive oxygen species, such as hydroxyl radicals, superoxide radicals, and singlet oxygen.

[0043] There are several main reasons for choosing cobalt and iron as doping metals: Firstly, Co 2+ ↔Co 3+ Fe 2+ ↔Fe 3+ First, the valence state cycle, coupled with the valence state changes of rare earth ions, can significantly enrich oxygen vacancies. Second, interfacial electron transfer can accelerate oxygen adsorption-dissociation, promoting the efficient generation of superoxide radicals, hydroxyl radicals, etc. Third, the ionic radius is well-matched, making it easy to form solid solutions in fluorite and La3 type lattices, avoiding heterogeneous phase separation. Fourth, after doping with rare earth metals containing intrinsic oxygen vacancies, it has significant effects on increasing the number of oxygen vacancies, extending the lifetime of reactive oxygen species, increasing the total amount of reactive oxygen species, and accelerating oxygen vacancy regeneration. Fifth, cobalt and iron are magnetic metals, and after doping, they can be used as a medium for magnetic control.

[0044] Transition metals such as nickel, manganese, copper, and zinc are not applicable to this invention. The variable valence of nickel (Ni...) 2+ / Ni 3+ Nickel typically requires a very high potential, resulting in low efficiency in the Fenton reaction. Furthermore, when nickel or nickel oxide comes into contact with rare earth oxides, its high work function easily leads to the formation of a Schottky barrier at the interface, hindering the flow of electrons from the rare earth oxide to nickel (or vice versa), thus suppressing the separation and migration of interfacial charges and inhibiting the formation of reactive oxygen species. Manganese possesses multiple valence states from +2 to +7 (Mn). 2+ , Mn 3+ ,Mn 4+ , Mn 6+ , Mn 7+In complex antibacterial environments, multiple valence states can make reaction pathways difficult to control. These intermediate states may react with the target reactive oxygen species (ROS) or cause electrons to cycle ineffectively between multiple valence states, reducing the efficiency of ROS generation. Furthermore, manganese complexes have poor structural stability. Copper itself is a broad-spectrum antibacterial metal (e.g., verdigris). However, its main antibacterial mechanisms are contact sterilization and ion leaching toxicity—that is, the release of Cu... 2+ The ions themselves are highly toxic to bacteria, which does not match the oxygen vacancy synergistic target of this invention. Furthermore, while the addition of copper can generate some ROS, its dominant ion dissolution mechanism masks or replaces the contribution of oxygen vacancy catalysis. Zinc has a single valence state, almost exclusively existing as Zn in compounds. 2+ It exists in a specific form. This means that it cannot participate in the Fenton reaction or catalyze the formation of ROS from oxygen through a variable valence cycle like iron and cobalt. Furthermore, manganese, copper, and zinc are not ferromagnetic.

[0045] Therefore, this invention enhances the antibacterial properties of materials by designing rare earth metal oxides with intrinsic oxygen vacancies and variable-valence transition metals, through the synergistic effect of interface engineering and defect engineering. Doping with variable-valence transition metal ions can enhance redox cycles and construct heterogeneous interfaces, promote oxygen vacancy formation and regeneration, optimize interface charge transfer, and significantly improve the efficiency and quantity of generating reactive oxygen species. If either a rare earth metal oxide with intrinsic oxygen vacancies or a variable-valence transition metal is lacking, the variable-valence transition metal alone will have almost no antibacterial properties in the glaze; if the variable-valence transition metal is lacking, the antibacterial properties of a rare earth metal oxide alone with intrinsic oxygen vacancies in the glaze will be significantly reduced.

[0046] Then, an exemplary method for preparing magnetic composite antibacterial materials by doping rare earth metals is described.

[0047] Dissolve appropriate amounts of transition metal salts and rare earth metal salts in a solvent in a certain proportion, then add an appropriate amount of complexing agent, stir and react (e.g., for 20-30 min), add an appropriate amount of gelling agent, and continue stirring and reacting (e.g., at 70-75℃ for 1-2 h) to obtain a gel-like primary product.

[0048] The transition metal salt can be at least one of cobalt, iron hydrated nitrates or chlorides. The rare earth metal salt can be at least one of cerium, gadolinium, samarium, yttrium hydrated nitrates or chlorides. The molar ratio of transition metal to rare earth metal is 1:(6~9). If the molar ratio of transition metal to rare earth metal exceeds the above range, the effect will be weak if the doping amount is too low. A small amount of iron / cobalt cannot form an effective charge transfer channel or a sufficient heterojunction interface inside the material, and has limited effect on improving the concentration and activity of oxygen vacancies. If the doping amount is too high, exceeding the solid solubility, it will cause lattice collapse and the appearance of impurity phases, which will cover the active sites. In addition, excessive doping will cause oxygen vacancies to recombine and disappear, and the number of active sites will decrease instead of increase.

[0049] The solvent may be deionized water. The complexing agent (reactant) is at least one of citric acid and glacial acetic acid. The complexing agent needs to be dissolved in a small amount of water at 50°C before being added slowly dropwise. For example, the molar ratio of deionized water, total metal salt and complexing agent is (330~390):1:(1.0~1.5).

[0050] The gelling agent is at least one of ethylene glycol or glycerol. The amount of gelling agent used can be 10 mL / 0.1 mol (total metal salts).

[0051] The primary product is dried under certain conditions to obtain a dry gel-like primary product. After grinding and sieving, it is calcined for a period of time and then cooled to obtain a powdered metal-modified doped composite material. Iron or cobalt ions enter the crystal lattice of rare earth oxides, replacing some of the rare earth ion positions.

[0052] The drying under specific conditions involves drying at 60-70℃ for 5-6 hours, followed by further drying at 100-120℃ for 10-12 hours (gradual heating to prevent gel bursting). The grinding is performed using an agate mortar and pestle. The sieving is done through a 320-mesh standard sieve. The calcination is carried out at 300-500℃ for 2-4 hours. The particle size of the powdered metal-modified doped composite material is 20-200 nm.

[0053] The metal-modified doped composite material was dispersed in deionized water, and then an appropriate amount of coating solution was added. After stirring and mixing evenly, a mixture was obtained. The coating solution was an aqueous solution of sodium alginate. The mass ratio of the metal-modified doped composite material, sodium alginate and water in the mixture was 5~10:1~1.5:90~95.

[0054] The solution is atomized using a spray gun and stirred. After reacting for 5-10 hours, the filter cake is collected, washed 2-3 times with water, and then dried at 100-120℃ for 10-12 hours to obtain the magnetic composite antibacterial material. The curing solution is a 2%-6% (w / w) calcium chloride aqueous solution.

[0055] The spray gun atomizes the mixture into nano-sized droplets. When these droplets contact the curing liquid, calcium ions instantly combine with the α-L-guluronic (G) units in the sodium alginate structure, forming a dense gel film that maintains a spherical or near-spherical shape under surface tension. Further, the calcium ions diffuse into the droplets, continuing the cross-linking reaction and ultimately forming uniform gel spheres. After drying, this results in a spherical or near-spherical magnetic composite antibacterial material with a smooth and uniform surface, significantly reducing its resistance to movement within the glaze.

[0056] Furthermore, the preparation method of the antibacterial ceramic plate of the present invention includes: adding a magnetic composite antibacterial material to a traditional ceramic glaze, stirring and mixing it evenly to obtain a magnetic antibacterial glaze. During the glazing process, an external magnetic field is applied to control the position of the magnetized composite antibacterial material. Consistent with traditional production processes, the ceramic plate with antibacterial function is obtained after drying and firing.

[0057] The traditional ceramic glazes include, but are not limited to, polished glaze, antique glaze, low-gloss glaze, dry granule glaze, and skin-feel glaze.

[0058] The mass ratio of the magnetic composite antibacterial material to the ceramic glaze in the magnetic antibacterial glaze is (1.5~3):100. The specific gravity of the ceramic glaze is 1.65~1.75 g / cm³. 3 In an optional embodiment, the amount of magnetic antibacterial glaze applied is 700~1100 g / m³. 2 Insufficient glaze application results in a grainy texture on the surface of the ceramic slab, affecting its stain resistance and feel. The main reasons are: firstly, insufficient glaze application cannot fill defects on the surface of the ceramic body, leading to a grainy texture; secondly, if magnetic composite antibacterial material particles are added to the glaze, insufficient glaze application at high temperatures will prevent the glaze from fully encapsulating the particles, leaving some exposed and creating a grainy texture. Excessive application will affect the movement speed of the magnetic composite antibacterial material within the glaze, thus impacting the antibacterial effect. Additionally, an excessively thick glaze layer can obscure the design, affecting its color development.

[0059] The strength of the external magnetic field can be 15,000 to 20,000 Gauss. The external magnetic field is applied by installing a permanent magnet or electromagnet above the front of the brick blank. When the magnetic antibacterial glaze is poured onto the brick blank through the bell jar, the magnetic antibacterial composite material in it rapidly migrates to the surface under the action of the magnetic field force and accumulates on the glaze surface.

[0060] The firing temperature can be 1120~1180℃, and the firing time can be 40~70 min.

[0061] By using a magnetic field to concentrate magnetic composite antibacterial materials on the surface or top of the glaze layer, the distance between the magnetic composite antibacterial materials and air and water is shortened, increasing the number of exposed active sites, improving the efficiency of reactive oxygen generation, and enhancing antibacterial performance.

[0062] This invention selects specific transition metals and rare earth metals with intrinsic metal oxygen vacancies for doping to prepare magnetic composite antibacterial materials, significantly enhancing the catalytic activity of rare earth metals. These materials are then combined with ceramic glazes and positioned using a magnetic field. This allows for direct application in the production of antibacterial ceramic slabs with stable and long-lasting antibacterial effects without compromising decorative appeal. The ceramic slabs exhibit antibacterial rates exceeding 99% against both *Escherichia coli* and *Staphylococcus aureus*. Furthermore, the gloss change of the ceramic glaze used in the ceramic slabs after firing before and after the addition of the magnetic antibacterial composite material is within 10°, preferably within 3°.

[0063] The following examples further illustrate the present invention in detail. It should also be understood that the following examples are only for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention are within the scope of protection of the present invention. The specific process parameters, etc., in the following examples are merely examples within a suitable range; that is, those skilled in the art can make appropriate selections within the appropriate range based on the description herein, and are not intended to be limited to the specific values ​​in the examples below.

[0064] Example 1

[0065] The preparation method of antibacterial ceramic plates includes the following steps:

[0066] (1) Weigh 291g of cobalt nitrate hexahydrate and 3908g of cerium nitrate hexahydrate and dissolve them in 5000g of deionized water. Stir at 300r / min for 20 min until completely dissolved. Then, dissolve 1921g of citric acid separately in 940g of hot water (50℃) and slowly add it dropwise to the metal salt solution. Continue stirring for 20 min to form a homogeneous complex solution. Next, add 1000 mL of ethylene glycol and heat the system to 70℃. Stir at 300r / min for 1 h. The solution gradually becomes viscous until a continuous, non-breakable gel thread can be formed when a glass rod is lifted. Stop stirring immediately to obtain a gel-like primary product.

[0067] (2) Transfer the gel to an oven and dry it at a low temperature of 60°C for 6 h, then raise the temperature to 100°C and dry it for 10 h until the gel is completely dehydrated into a loose dry gel. Grind the dry gel with an agate mortar and pestle, pass it through a 320-mesh standard sieve, and calcine it at 300°C for 2 h to obtain a powdered metal-modified doped composite material.

[0068] (3) Take an appropriate amount of the metal-modified doped composite material and disperse it evenly in water. Then add sodium alginate aqueous solution and stir to mix evenly to obtain a mixture (mass ratio of metal-modified doped composite material: sodium alginate: water = 5:1:95). Use a precision atomizing spray gun to atomize the mixture into the solidified liquid under stirring. After reacting for 5 h, filter, take the filter cake and wash it twice with water. Dry it at 120℃ for 10 h to obtain the magnetic composite antibacterial material. The solidified liquid is a 4% (w / w) calcium chloride aqueous solution.

[0069] (4) Take ordinary matte glaze (chemical composition including: by mass percentage, 46.1% SiO2, 22.7% Al2O3, 0.13% Fe2O3, 9.03% CaO, 2.00% MgO, 0.47% K2O, 4.72% Na2O, 0.35% P2O5, 4.76% ZnO, 0.32% BaO, 9.42% LOI) and pass it through a 120-mesh sieve, then adjust the specific gravity to 1.65 g / cm³. 3 After adding magnetic composite antibacterial material and stirring to disperse it evenly, magnetic antibacterial glaze is obtained (mass ratio of magnetic composite antibacterial material to matte glaze = 1.5:100).

[0070] (5) During the glazing process of the bell jar, a square permanent magnet with a magnetic field strength of 15,000 Gauss is added directly above the body to control the direction and position of the magnetized functional material. The amount of magnetic antibacterial glaze applied is 700 g / m². 2 Then it is fired in a roller kiln at 1120℃ for 40 minutes, and the resulting ceramic plate has antibacterial function.

[0071] Example 2

[0072] The preparation method of antibacterial ceramic plates includes the following steps:

[0073] (1) Weigh 416g of cobalt nitrate hexahydrate and 3810g of samarium nitrate hexahydrate and dissolve them in 6000g of deionized water. Stir at 300 r / min for 30 min until completely dissolved. Then, dissolve 2305g of citric acid separately in 1020g of 50℃ hot water and slowly add it dropwise to the metal salt solution. Continue stirring for 30 min to form a homogeneous complex solution. Next, add 1000mL of ethylene glycol and heat the system to 60℃. Stir at 300 r / min for 2 h. The solution gradually becomes viscous until a continuous, non-breakable gel thread can be formed when a glass rod is lifted. Stop stirring immediately to obtain a gel-like primary product.

[0074] (2) Transfer the gel to an oven and dry it at a low temperature of 60°C for 5 h, then raise the temperature to 100°C and dry it for 12 h until the gel is completely dehydrated into a loose dry gel. Grind the dry gel with an agate mortar and pestle, pass it through a 320-mesh standard sieve, and calcine it at 500°C for 4 h to obtain a powdered metal-modified doped composite material.

[0075] (3) Take an appropriate amount of the metal-modified doped composite material and disperse it evenly in water. Then add sodium alginate aqueous solution and stir to mix evenly to obtain a mixture (mass ratio of metal-doped composite material: sodium alginate: water = 10:1.5:90). Use a precision atomizing spray gun to atomize the mixture into the solidified liquid under stirring. After reacting for 10 h, filter, take the filter cake and wash it with water 3 times. Dry it at 100℃ for 12 h to obtain the magnetic composite antibacterial material. The solidified liquid is a 4% (w / w) calcium chloride aqueous solution.

[0076] (4) Take the matte glaze (chemical composition including: by mass percentage, 46.1% SiO2, 22.7% Al2O3, 0.13% Fe2O3, 9.03% CaO, 2.00% MgO, 0.47% K2O, 4.72% Na2O, 0.35% P2O5, 4.76% ZnO, 0.32% BaO, 9.42% LOI) and pass it through a 120-mesh sieve, then adjust the specific gravity to 1.75 g / cm³. 3 After adding magnetic composite antibacterial material and stirring to disperse it evenly, magnetic antibacterial glaze is obtained (mass ratio of magnetic composite antibacterial material to matte glaze = 3:100).

[0077] (5) During the glazing process of the bell jar, a square permanent magnet with a magnetic field strength of 20,000 Gauss is added directly above the blank to control the movement direction and position of the magnetized functional material. The amount of magnetic antibacterial glaze applied is 1100 g / m². 2 Then it is fired in a roller kiln at 1180℃ for 70 minutes, and the resulting ceramic plate has antibacterial function.

[0078] Example 3 (Doping with nickel salt)

[0079] Same as Example 1, except that 291g of cobalt nitrate hexahydrate was replaced with 290.8g of nickel nitrate hexahydrate to prepare a ceramic plate with antibacterial function.

[0080] Example 4 (Excessive use of variable valence transition metal)

[0081] Same as Example 1, except that the amount of cobalt nitrate hexahydrate added was increased to 582g to prepare a ceramic plate with antibacterial function.

[0082] Example 5 (Insufficient amount of variable valence transition metal)

[0083] Same as Example 1, except that the amount of cobalt nitrate hexahydrate added was reduced to 145g to prepare a ceramic plate with antibacterial function.

[0084] Example 6 (Insufficient application of magnetic antibacterial glaze)

[0085] Same as Example 1, except that the amount of magnetic antibacterial glaze applied is 500 g / m². 2 A ceramic plate with antibacterial function was prepared.

[0086] Example 7 (using rare earth metals without intrinsic oxygen vacancies)

[0087] Same as Example 1, except that 3908g of cerium nitrate hexahydrate was replaced with 3897g of lanthanum nitrate hexahydrate to prepare a ceramic plate with antibacterial function.

[0088] Example 8 (Excessive application of magnetic antibacterial glaze)

[0089] Same as Example 1, except that the amount of magnetic antibacterial glaze applied is 1300 g / m². 2 A ceramic plate with antibacterial function was prepared.

[0090] Example 9 (using high-gloss glaze)

[0091] Same as Example 1, except that the matte glaze is replaced with a high-gloss glaze. The chemical composition of the high-gloss glaze includes, by mass percentage: SiO2 53%, Al2O3 12%, Fe2O3 0.1%, CaO 8%, MgO 3%, K2O 0.6%, Na2O 6%, P2O5 0.3%, ZnO 2%, BaO 2%, SrO 2%, LOI 11%.

[0092] Comparative Example 1 (Ordinary matte glaze, without added antibacterial materials)

[0093] The process is essentially the same as in Example 1, except that conventional matte glaze is used for glazing, and no antibacterial materials are added. This yields a standard ceramic slab.

[0094] Comparative Example 2 (No external magnetic field was applied during the glazing process).

[0095] The process is basically the same as in Example 1, except that no magnet is added during the glazing process of the bell jar. After glazing and drying, the glaze is fired at 1120°C for 40 minutes in a roller kiln, and the resulting ceramic plate has antibacterial function.

[0096] Comparative Example 3 (using a metal-modified doped composite material without surface treatment with sodium alginate aqueous solution)

[0097] The process is basically the same as in Example 1, except that step (3) is removed and the magnetic composite antibacterial material in step (4) is replaced with a metal-modified doped composite material. A ceramic plate with antibacterial function is thus obtained.

[0098] Comparative Example 4 (using a mixture of nanopowders of transition metal oxides and rare earth metal oxides)

[0099] (1) Take ordinary matte glaze (chemical composition including: by mass percentage, 46.1% SiO2, 22.7% Al2O3, 0.13% Fe2O3, 9.03% CaO, 2.00% MgO, 0.47% K2O, 4.72% Na2O, 0.35% P2O5, 4.76% ZnO, 0.32% BaO, 9.42% LOI) and pass it through a 120-mesh sieve, then adjust the specific gravity to 1.65 g / m³. 2 Add a mixture of cobalt oxide and cerium oxide (cobalt oxide:cerium oxide molar ratio = 1:9, particle size 100 nm). After stirring and dispersing evenly, an antibacterial glaze is obtained (mixture:matte glaze mass ratio = 1.5:100).

[0100] (2) During the glazing process of the bell jar, a square permanent magnet with a magnetic field strength of 15,000 Gauss is added directly above the blank to control the movement direction and position of the magnetized functional material. The amount of antibacterial glaze applied is 700 g / m². 2 Then it is fired in a roller kiln at 1120℃ for 40 minutes, and the resulting ceramic plate has antibacterial function.

[0101] Performance testing methods

[0102] The gloss of the ceramic slabs was tested using a KOSAI WGG60-Y4 gloss meter with a graduation of 0.1 GU. The stain resistance of the ceramic slabs was tested according to the relevant methods and index requirements in GB / T 3810.14-2016 Ceramic Tiles Test Methods Part 14: Determination of Stain Resistance. The antibacterial performance was tested according to the relevant test methods and index requirements in industry standard JC / T 897-2014. The results are shown in Table 1.

[0103] Table 1. Test results for anti-fogging, antibacterial, and gloss properties.

[0104]

[0105] According to Table 1, the antibacterial ceramic plate developed in this invention has excellent anti-fouling and antibacterial effects, and the introduction of antibacterial components has minimal impact on the gloss of the ceramic plate surface.

[0106] It can be seen that the antibacterial effect of nickel doping rare earth metal oxides in Example 3 is poor, mainly because the valence state cycling barrier of nickel is too high, which prevents the valence state from cycling under room temperature conditions and thus fails to produce a synergistic antibacterial effect with rare earth metals.

[0107] It can be seen that the antibacterial performance of Example 4 is significantly reduced. This is because the excessive cobalt doping exceeds the solid solubility, leading to lattice collapse and the appearance of impurity phases, which cover the active sites. In addition, excessive doping causes oxygen vacancies to recombine and disappear, resulting in a decrease in the number of active sites instead of an increase.

[0108] It can be seen that the antibacterial performance of Example 5 is significantly reduced. This is because a small amount of cobalt cannot form an effective charge transfer channel or a sufficient heterojunction interface inside the material, thus having a limited effect on improving the concentration and activity of oxygen vacancies.

[0109] It can be seen that the stain resistance of the brick surface in Example 6 decreased. This is because the amount applied was too low, resulting in a grainy texture on the surface of the ceramic glaze layer (e.g., ...). Figure 5 As shown, this affects the stain resistance and feel of the ceramic plate surface.

[0110] It can be seen that Example 7 exhibits poor antibacterial performance, which is also a bottleneck in improving the antibacterial performance of antibacterial ceramics. Many technical solutions prepare sintered antibacterial ceramics with antibacterial performance that can reach 95%-97%, but cannot stably reach 99%. The main reason is that rare earth metal oxides without intrinsic oxygen vacancies have very few surface active sites, and the number of newly constructed vacancies through doping is small.

[0111] It can be seen that the antibacterial performance of Example 8 decreased. This is because the application amount was too high, which affected the movement speed of the magnetic composite antibacterial material in the glaze, thus affecting the antibacterial effect. Furthermore, obvious opacity appeared on the brick surface (such as...). Figure 6 (As shown).

[0112] As can be seen, the introduction of the magnetic antibacterial composite material in Example 9 significantly altered the gloss of the high-gloss glaze. This is because the high-gloss glaze has a high silicon content and a low aluminum content, relying on high fluidity to level and form a mirror surface at high temperatures. The introduction of the magnetic antibacterial composite material, due to the high melting temperature of rare earth metals, increases the viscosity of the glaze melt, reduces fluidity, and affects surface gloss. Furthermore, at high temperatures, some unmelted particles remain in the rare earth metal oxides, increasing the roughness of the glaze surface.

[0113] It can be seen that in Comparative Example 2, removing the external magnetic field had a significant impact on the antibacterial properties during the preparation of the antibacterial ceramic plate. This is because the antibacterial material settled in the glaze, resulting in a substantial reduction in the number of antibacterial active sites on the glaze surface.

[0114] It can be seen that the lack of surface treatment on the metal-modified antibacterial composite material in Comparative Example 3 also significantly affected the final antibacterial performance. This is because the uncoated antibacterial agent has an irregular shape, which results in greater resistance to movement in the glaze and makes it unable to migrate stably under the influence of a magnetic field, leading to insufficient or unstable antibacterial performance (the surface-treated antibacterial agent is almost spherical or ellipsoidal with a smooth surface).

[0115] It can be seen that the antibacterial performance of the magnetic composite antibacterial material prepared by metal modification and doping in Comparative Example 4 is significantly enhanced compared with the mixture of nanoparticles of modified metal oxide and rare earth metal oxide.

Claims

1. A method for preparing a ceramic plate with antibacterial function, characterized in that, The preparation method includes: A magnetic composite antibacterial material is added to a ceramic glaze and mixed evenly to obtain a magnetic antibacterial glaze. The magnetic composite antibacterial material comprises a metal-modified doped composite material formed by a variable-valence transition metal and a rare-earth metal with intrinsic oxygen vacancies, and a coating layer covering the surface of the metal-modified doped composite material. The variable-valence transition metal is selected from cobalt, and the rare-earth metal with intrinsic oxygen vacancies is selected from at least one of cerium, gadolinium, samarium, and yttrium. The molar ratio of the variable-valence transition metal to the rare-earth metal is 1:(6~9). The coating layer is made of sodium alginate. The ceramic glaze is a matte glaze, and the chemical composition of the matte glaze includes, by mass percentage: SiO2 43%~48%, Al2O3 20%~25%, Fe2O3 0.05%~0.2%, CaO 8%~10%, MgO 1%~3%, K2O 0.1%~1%, Na2O 4%~6%, P2O5 0.1%~0.5%, ZnO 4%~6%, BaO 0.2%~0.5%, LOI 9%~11%; the mass ratio of the magnetic composite antibacterial material to the ceramic glaze in the magnetic antibacterial glaze is (1.5~3):100; wherein, the specific gravity of the ceramic glaze is 1.65~1.75 g / cm³. 3 ; The magnetic antibacterial glaze is applied to the surface of the ceramic blank; during the glazing process, an external magnetic field is applied to control the movement path and / or position of the magnetic composite antibacterial material; the magnetic antibacterial glaze is applied by pouring; the amount of magnetic antibacterial glaze applied is 700~1100 g / m³. 2 ; The ceramic blank with the magnetic antibacterial glaze applied is fired to obtain a ceramic plate with antibacterial function.

2. The method for preparing the antibacterial ceramic plate according to claim 1, characterized in that, The preparation method of the magnetic composite antibacterial material includes: (1) Dissolve transition metal salts and rare earth metal salts fully in a solvent, then add a complexing agent, stir the reaction, add a gelling agent, and continue stirring the reaction to obtain a gel-like primary product; (2) After drying the primary product, a dry gel-like primary product is obtained. After grinding, sieving and calcining, a powdered metal-modified doped composite material is obtained. (3) Disperse the metal-modified doped composite material in a solvent, then add the coating liquid, mix evenly, and obtain the precursor liquid; (4) The precursor liquid is atomized into the stirred curing liquid. After the curing reaction, the product is collected, filtered, washed and dried to obtain the magnetic composite antibacterial material.

3. The method for preparing the antibacterial ceramic plate according to claim 2, characterized in that, In step (1), the transition metal salt is at least one of cobalt nitrate, ferric nitrate, cobalt chloride, ferric chloride or their hydrates; the rare earth metal salt is selected from at least one of cerium nitrate, gadolinium nitrate, samarium nitrate, yttrium nitrate, cerium chloride, gadolinium chloride, samarium chloride, yttrium chloride or their hydrates.

4. The method for preparing the antibacterial ceramic plate according to claim 2, characterized in that, The complexing agent is at least one of citric acid and glacial acetic acid, and the gelling agent is at least one of ethylene glycol and glycerol; the molar ratio of the total amount of transition metal salts and rare earth metal salts to the complexing agent is 1:(1.0~1.5); the amount of gelling agent used is 5~20 mL / 0.1 mol total metal salt.

5. The method for preparing the antibacterial ceramic plate according to claim 2, characterized in that, In step (2), the drying is performed at 60-70℃ for 5-6 h, followed by heating to 100-120℃ and continuing drying for 10-12 h; the calcination is performed at 300-500℃ for 2-4 h; and the particle size of the powdered metal-modified doped composite material is 20-200 nm.

6. The method for preparing an antibacterial ceramic plate according to claim 2, characterized in that, In step (3), the coating solution is an aqueous solution of sodium alginate; the mass ratio of sodium alginate in the metal-modified doped composite material and the coating solution is 5~10:1~1.

5.

7. The method for preparing the antibacterial ceramic plate according to claim 2, characterized in that, In step (4), the curing liquid is a calcium chloride aqueous solution with a mass concentration of 2% to 6%.

8. The method for preparing an antibacterial ceramic plate according to claim 1, characterized in that, The strength of the applied magnetic field is 15,000 to 20,000 Gauss.

9. The method for preparing an antibacterial ceramic plate according to claim 1, characterized in that, The firing temperature is 1120~1180℃, and the firing time is 40~70 min.

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