Antibacterial agent, antibacterial glaze and antibacterial tile and preparation method thereof

Abstract

The present invention relates to the field of architectural ceramics and discloses an antibacterial agent, an antibacterial glaze, and an antibacterial ceramic tile, and methods for preparing the same. The antibacterial agent is a porous, spiny-spherical nanosilver dispersion. The preparation method comprises the following steps: S1, mixing a silver nitrate solution with a first reducing agent solution, stirring the mixture, and reacting in the dark for 18-24 hours; S2, adding a second reducing agent to the mixed solution of step S1, stirring the mixture, and reacting in the dark for 7-10 days, thereby obtaining the nanosilver dispersion. The first reducing agent is at least one of catechin, vitamin C, and tea polyphenols; and the second reducing agent is sodium citrate. The present invention provides a method for synthesizing porous, spiny-spherical nanosilver. The spiny-spherical nanosilver exhibits excellent antibacterial and bactericidal effects and also possesses an electromagnetic antibacterial effect induced by heat source excitation, which can expand the antibacterial range. When the antibacterial agent is applied to ceramic glazes, the fired ceramics exhibit stable and long-lasting antibacterial effects.

Description

Technical Field

[0001] The present invention relates to the field of building ceramics, and in particular to an antibacterial agent, an antibacterial glaze, an antibacterial tile and a preparation method thereof. Background Art

[0002] In recent years, with people's increasing emphasis on healthy living environments, demand for ceramic tiles with antibacterial and bactericidal properties has grown significantly in applications such as healthcare, home furnishings, and public facilities. Currently, antibacterial tile technologies in the domestic ceramics industry fall primarily into two categories: antibacterial glaze technology and antibacterial surface treatment technology. However, both of these mainstream technologies face significant technical bottlenecks, limiting their reliability and long-term effectiveness in practical applications.

[0003] 1. Limitations of antibacterial surface treatment technology

[0004] Currently, some ceramic tiles utilize antibacterial waxes or functional coatings applied to their surfaces to achieve an antibacterial effect. For example, while organic antibacterial coatings (such as quaternary ammonium salts and silver ion complexes) offer significant initial antibacterial properties, their effectiveness is short-lived due to the degradation characteristics of organic materials, making them inadequate for the long lifespan of durable ceramic tiles. Inorganic antibacterial fillers (such as nano-zinc oxide and titanium dioxide) offer excellent stability but exhibit poor adhesion to the tile substrate, leading to coating loss due to wear and cleaning, and rapid degradation of their antibacterial properties. Consequently, these surface treatment technologies struggle to achieve both long-term antibacterial efficacy and durability, limiting their practical application.

[0005] 2. Stability issues of antibacterial glaze technology

[0006] Compared with surface treatment technology, antibacterial glaze technology uses high-temperature sintering to consolidate antibacterial components (such as metal oxides such as silver, copper, and zinc) into the glaze layer, which can theoretically achieve a more lasting antibacterial effect. However, this technology faces the problem of sintering process sensitivity in actual production: slight fluctuations in the glaze formula, sintering temperature, and atmosphere may lead to uneven distribution or loss of activity of antibacterial components, resulting in significant differences in the antibacterial performance of different batches of products, or even complete failure. In addition, existing technologies have also explored antibacterial methods that stimulate the glaze surface to produce negative oxygen ions or photocatalytic reactions (such as TiO2 photocatalysis) through light, but these methods usually rely on short-wavelength ultraviolet light (<400nm) for excitation. The intensity of ultraviolet light in daily environments is insufficient, making it difficult to continuously trigger an effective antibacterial effect, limiting its practicality.

[0007] In summary, existing antibacterial tile technologies, due to insufficient durability, poor process stability, or reliance on demanding activation conditions, cannot simultaneously meet the requirements for long-lasting antibacterial performance, high adhesion, process stability, and universal application. Therefore, developing a tile antibacterial technology that combines high-efficiency, long-lasting antibacterial performance, excellent physical stability, easier activation, and suitability for industrial production has become a key issue in this field that urgently needs to be broken through. Summary of the Invention

[0008] The main purpose of the present invention is to propose an antibacterial agent that can be used in ceramic glazes. The prepared antibacterial glaze is applied to the surface of the ceramic tile body and fired to produce ceramic tiles with good and long-lasting antibacterial and bactericidal effects and high production stability.

[0009] To achieve the above object, the present invention provides an antibacterial agent, which is a nanosilver dispersion in the shape of porous spherical balls; and a method for preparing the nanosilver dispersion comprises the following steps:

[0010] S1. Mix the silver nitrate solution and the first reducing agent solution and stir them in the dark for 18-24 hours.

[0011] S2, adding a second reducing agent to the mixed solution of step S1, mixing and stirring, and reacting in the dark for 7 to 10 days to obtain the nanosilver dispersion;

[0012] The first reducing agent is at least one of catechin, vitamin C and tea polyphenols;

[0013] The second reducing agent is sodium citrate.

[0014] The present invention provides a method for synthesizing porous spiny spherical nanosilver. The spiny spherical nanosilver has excellent antibacterial and bactericidal effects and also has an electromagnetic antibacterial effect stimulated by a heat source, and the heat source stimulation can expand the antibacterial range.

[0015] Preferably, the concentration of the silver nitrate solution is 1-1.7 g / L.

[0016] Preferably, the concentration of the first reducing agent solution is 1.18-2.00 g / L.

[0017] Preferably, the molar ratio of the silver nitrate to the first reducing agent is 2:1 to 3:1.

[0018] Preferably, the molar ratio of the silver nitrate to the second reducing agent is 3:2 to 2:1.

[0019] The present invention also provides an antibacterial glaze comprising a base glaze and the above-described antibacterial agent; the antibacterial agent is added in an amount of 5 to 10% based on the total weight of the base glaze being 100%. The base glaze is a conventional glaze formula used in the ceramic industry.

[0020] The thorny spherical nanosilver is added into the glaze to form an antibacterial glaze, so that the antibacterial glaze also has a long-lasting antibacterial and bactericidal effect.

[0021] The present invention also provides an antibacterial ceramic tile, which at least comprises a body layer and a surface glaze layer, wherein the surface glaze layer is fired using the antibacterial glaze as described above.

[0022] Tiles fired with this antibacterial glaze can inhibit the growth of E. coli and exhibit excellent bactericidal and antibacterial effects. Furthermore, under 37°C heat source excitation, the electromagnetic antibacterial effect of heat source excitation can expand the range of antibacterial inhibition and achieve non-contact antibacterial inhibition. Compared with the short-wavelength excitation conditions used in existing technologies, the heat source excitation conditions provided by this invention are easier to implement and can achieve a stronger antibacterial effect when combined with heating rock slabs, heating tiles, etc.

[0023] The present invention also provides a method for preparing the antibacterial ceramic tile, comprising the following steps:

[0024] A. dry-mixing and ball-milling the basic glaze according to the formula of the basic glaze to obtain a basic glaze;

[0025] B. adding the antibacterial agent to the basic glaze to obtain the antibacterial glaze;

[0026] C. Applying the antibacterial glaze to the surface of the ceramic tile body, drying it, and then firing it in a kiln. After polishing, the antibacterial ceramic tile is obtained.

[0027] Compared with the existing technology, the present invention has at least the following beneficial effects: the antibacterial agent provided by the present invention is applied to ceramic glaze and still has a stable and long-lasting antibacterial and bactericidal effect after sintering. At the same time, it has an electromagnetic antibacterial effect stimulated by a heat source. At an ambient temperature of 37°C, the antibacterial range is expanded, and the electromagnetic antibacterial range is about 1mm, which has the application prospect of non-contact antibacterial. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0029] Figure 1 This is the SEM image (5 μm) of the nanosilver prepared in Example 2;

[0030] Figure 2 This is the SEM image of the silver nanoparticles prepared in Example 2 (200 nm);

[0031] Figure 3 This is the SEM image (5 μm) of the nanosilver prepared in Comparative Example 1;

[0032] Figure 4 This is a graph showing the antibacterial range of nanosilver dispersions of different concentrations in Example 7 under constant temperature incubation at 37°C;

[0033] Figure 5 This is a diagram showing the antibacterial range of nanosilver dispersions of different concentrations in Example 8 under constant temperature cultivation at 23°C.

[0034] The realization of the objectives, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. It should be noted that the embodiments in this application and the features in the embodiments can be combined with each other unless there is a conflict. 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 not mentioned in detail are all process steps or preparation methods known to those skilled in the art.

[0036] A bacteriostatic agent is a porous spiny spherical nanosilver dispersion; the preparation method of the nanosilver dispersion comprises the following steps:

[0037] S1. Mixing a silver nitrate solution having a concentration of 1-1.7 g / L and a first reducing agent solution having a concentration of 1.18-2.00 g / L at a molar ratio of silver nitrate to the first reducing agent of 2:1-3:1, and reacting for 18-24 hours in the dark;

[0038] S2. Adding the second reducing agent to the mixed solution of step S1 at a molar ratio of silver nitrate to the second reducing agent of 3:2 to 2:1, mixing and stirring, and reacting in the dark for 7 to 10 days to obtain a nanosilver dispersion;

[0039] The first reducing agent is at least one of catechin, vitamin C and tea polyphenols; and the second reducing agent is sodium citrate.

[0040] An antibacterial glaze comprises a basic glaze and the above-mentioned antibacterial agent; based on the total weight of the basic glaze being 100%, the added amount of the antibacterial agent is 5-10%.

[0041] In the prior art, nanosilver is typically prepared by reacting a silver salt with a reducing agent. The first reducing agent used in the present invention includes catechin, vitamin C, and tea polyphenols, all of which are suitable as reducing agents for nanosilver production. More preferably, plant extracts containing polyphenolic structures, such as catechin and tea polyphenols, are more environmentally friendly. However, nanosilver synthesized directly by reacting a silver salt with the first reducing agent often aggregates or grows in a spreading manner. After application to tile glaze and firing, it is difficult to evenly disperse on the tile surface, resulting in a poorly balanced antibacterial effect on the tile surface. To address this issue, the inventors attempted to prepare nanosilver with different structures. First, a water-soluble silver salt, namely silver nitrate, was used. Secondly, by adding the reducing agent in stages, first reacting the first reducing agent with the silver salt, and then adding a weakly alkaline reducing agent, namely sodium citrate, to the reaction, they were able to synthesize loose, porous, spiny nanosilver spheres. This allows the nanosilver mixed into the glaze to be more uniformly exposed to the tile surface after polishing, exerting its bactericidal and antibacterial effects through both contact and non-contact methods.

[0042] It should be noted that the base glaze described in the present invention is a conventional glaze formula used in the ceramic industry, and technicians can select an appropriate base glaze formula as needed. The antibacterial agent provided by the present invention can be mixed with a variety of conventional glazes in the prior art to achieve antibacterial and bactericidal effects.

[0043] An antibacterial ceramic tile comprises at least a body layer and a surface glaze layer, wherein the surface glaze layer is fired using the antibacterial glaze as described above.

[0044] The method for preparing the antibacterial ceramic tile comprises the following steps:

[0045] A. Dry-mix and ball-mill according to the formula of the basic glaze to obtain the basic glaze;

[0046] B. Add 5-10% of antibacterial agent to the basic glaze to obtain antibacterial glaze;

[0047] C. Apply antibacterial glaze to the surface of the ceramic tile body, dry it and send it into the kiln for firing. After polishing, the antibacterial ceramic tile is obtained.

[0048] Because the porous, spiny spherical nanosilver produced by the present invention exhibits electromagnetic antibacterial effects at 37°C, the antibacterial range is expanded and the antibacterial effect is enhanced. Therefore, the antibacterial glaze provided by the present invention, when combined with heating tiles, can achieve a stronger antibacterial effect and has broad application prospects in the field of non-contact antibacterial treatment. It should be noted that the above-mentioned preparation methods all utilize conventional, well-known glazing, glazing, tile firing, and polishing processes.

[0049] The following examples are further listed to illustrate the present invention in detail. It should also be understood that the following examples are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above content of the present invention all fall within the scope of protection of the present invention. The specific process parameters of the following examples are also only examples within a suitable range, that is, those skilled in the art can make selections within a suitable range through the description herein, and are not intended to be limited to the specific numerical values ​​of the examples below. For those in the examples where specific conditions are not specified, proceed according to conventional conditions or the conditions recommended by the manufacturer.

[0050] For example, the base glaze formulations used in Examples 1-5 and Comparative Examples 1-3 were all purchased from 1096 glaze from Foshan Yuanda Glaze Technology Co., Ltd. The base glaze used in Example 6 was purchased from RP502 glaze from Shandong Guoci Kanglitai New Materials Technology Co., Ltd. It should be understood that the antibacterial glazes provided in the examples of the present invention are merely illustrative. The base glazes provided by the present invention also provide excellent concealing effects. Those skilled in the art may select different ceramic glaze formulations as needed.

[0051] Example 1

[0052] Preparation of antibacterial agent:

[0053] S1. Boil 50 mL of pure water, add 2 g of catechin, stir until completely dissolved, dilute to 1 L, and let cool for later use; prepare 1.7 g / L silver nitrate solution and set aside; take 500 mL of silver nitrate solution and 500 mL of catechin solution and add them to a brown conical flask, mix and stir, and react in the dark for 24 hours;

[0054] S2. Add 0.58 g of sodium citrate to the mixed solution of step S1, mix and stir, and react in the dark for 7 days to obtain a nanosilver dispersion.

[0055] Preparation of antibacterial tiles:

[0056] A. Dry-mix and ball-mill according to the formula of the basic glaze to obtain the basic glaze;

[0057] B. Add 5% of antibacterial agent (nanosilver dispersion) to the basic glaze to obtain antibacterial glaze;

[0058] C. Apply antibacterial glaze to the surface of the ceramic tile body, dry it and send it into the kiln for firing. After polishing, the antibacterial ceramic tile is obtained.

[0059] Example 2

[0060] Preparation of antibacterial agent:

[0061] S1. Boil 50 mL of pure water, add 2 g of catechin, stir until completely dissolved, dilute to 1 L, and let cool for later use; prepare 1 g / L silver nitrate solution and set aside; take 500 mL of silver nitrate solution and 500 mL of catechin solution and add them to a brown conical flask, mix and stir, and react in the dark for 24 hours;

[0062] S2. Add 0.58 g of sodium citrate to the mixed solution of step S1, mix and stir, and react in the dark for 7 days to obtain a nanosilver dispersion.

[0063] Preparation of antibacterial tiles:

[0064] A. Dry-mix and ball-mill according to the formula of the basic glaze to obtain the basic glaze;

[0065] B. Add 5% of antibacterial agent (nanosilver dispersion) to the basic glaze to obtain antibacterial glaze;

[0066] C. Apply antibacterial glaze to the surface of the ceramic tile body, dry it and send it into the kiln for firing. After polishing, the antibacterial ceramic tile is obtained.

[0067] Example 3

[0068] Preparation of antibacterial agent:

[0069] S1. Boil 50 mL of pure water, add 2 g of catechin, stir until completely dissolved, dilute to 1 L, and let cool for later use; prepare 1 g / L silver nitrate solution and set aside; take 500 mL of silver nitrate solution and 500 mL of catechin solution and add them to a brown conical flask, mix and stir, and react in the dark for 24 hours;

[0070] S2. Add 1.16 g of sodium citrate to the mixed solution of step S1, mix and stir, and react in the dark for 7 days to obtain a nanosilver dispersion.

[0071] Preparation of antibacterial tiles:

[0072] A. Dry-mix and ball-mill according to the formula of the basic glaze to obtain the basic glaze;

[0073] B. Add 10% of antibacterial agent (nanosilver dispersion) to the basic glaze to obtain antibacterial glaze;

[0074] C. Apply antibacterial glaze to the surface of the ceramic tile body, dry it and send it into the kiln for firing. After polishing, the antibacterial ceramic tile is obtained.

[0075] Example 4

[0076] Preparation of antibacterial agent:

[0077] S1. Boil 50 mL of pure water, add 2 g of tea polyphenols, stir until completely dissolved, dilute to 1 L, and let cool for later use; prepare 1 g / L silver nitrate solution and set aside; take 500 mL of silver nitrate solution and 500 mL of tea polyphenols solution and add them to a brown conical flask, mix and stir, and react in the dark for 24 hours;

[0078] S2. Add 0.58 g of sodium citrate to the mixed solution of step S1, mix and stir, and react in the dark for 7 days to obtain a nanosilver dispersion.

[0079] Preparation of antibacterial tiles:

[0080] A. Dry-mix and ball-mill according to the formula of the basic glaze to obtain the basic glaze;

[0081] B. Add 5% of antibacterial agent (nanosilver dispersion) to the basic glaze to obtain antibacterial glaze;

[0082] C. Apply antibacterial glaze to the surface of the ceramic tile body, dry it and send it into the kiln for firing. After polishing, the antibacterial ceramic tile is obtained.

[0083] Example 5

[0084] Preparation of antibacterial agent:

[0085] S1. Boil 50 mL of pure water, add 2 g of vitamin C, stir until completely dissolved, dilute to 1 L, and let cool for later use; prepare 1 g / L silver nitrate solution and set aside; take 500 mL of silver nitrate solution and 500 mL of vitamin C solution and add them to a brown conical flask, mix and stir, and react in the dark for 24 hours;

[0086] S2. Add 0.58 g of sodium citrate to the mixed solution of step S1, mix and stir, and react in the dark for 7 days to obtain a nanosilver dispersion.

[0087] Preparation of antibacterial tiles:

[0088] A. Dry-mix and ball-mill according to the formula of the basic glaze to obtain the basic glaze;

[0089] B. Add 5% of antibacterial agent (nanosilver dispersion) to the basic glaze to obtain antibacterial glaze;

[0090] C. Apply antibacterial glaze to the surface of the ceramic tile body, dry it and send it into the kiln for firing. After polishing, the antibacterial ceramic tile is obtained.

[0091] Comparative Example 1

[0092] This comparative example adopts the same preparation method as Example 2, except that sodium citrate is not added in step S2.

[0093] Comparative Example 2

[0094] Preparation of antibacterial agent:

[0095] S1. Boil 50 mL of pure water, add 2 g of catechin and 0.58 g of sodium citrate, stir until completely dissolved, dilute to 1 L, and let cool for later use; prepare 1 g / L silver nitrate solution and set aside; take 500 mL of silver nitrate solution and 500 mL of a mixed solution of catechin and sodium citrate and add them to a brown conical flask, mix and stir, and react in the dark for 8 days to obtain a nanosilver dispersion.

[0096] Preparation of antibacterial tiles:

[0097] A. Dry-mix and ball-mill according to the formula of the basic glaze to obtain the basic glaze;

[0098] B. Add 5% of antibacterial agent (nanosilver dispersion) to the basic glaze to obtain antibacterial glaze;

[0099] C. Apply antibacterial glaze to the surface of the ceramic tile body, dry it and send it into the kiln for firing. After polishing, the antibacterial ceramic tile is obtained.

[0100] Comparative Example 3

[0101] In this comparative example, the ceramic tile body is directly glazed with the basic glaze without adding an antibacterial agent and then fired.

[0102] The bactericidal rate and antibacterial effect of the ceramic tile surfaces of Examples 1 to 5 and Comparative Examples 1 to 3 against Escherichia coli were tested. The test method was based on the national standard GB 4789.3-2016, as follows:

[0103] (1) The concentration of Escherichia coli spike solution is 10,000~100,000 CFU / mL, and it is diluted 100 times for later use;

[0104] (2) Take nine locations (the four corners and the four sides) of a tile and cut them into 100×100mm small square tiles. Take nine 20mm long transparent small round tubes and fix them on the tile surface with hot melt glue to form nine watch glasses with tile bottoms.

[0105] (3) Contact sterilization test: Add 5 mL of diluted E. coli spiked solution, pour in the colorimetric agar, cover with a glass dish, place in a 37°C constant temperature incubator, incubate for 12 h, remove and observe the number of green spots. Set up blank control 1 according to the contact sterilization test.

[0106] (4) Non-contact sterilization test: Pour an appropriate amount of color-developing agar into the test tube. After solidification (thickness less than 1 mm), add 5 mL of diluted E. coli spike solution. Cover the test tube with a glass dish and place it in a 37°C constant temperature incubator. Incubate for 12 hours. Remove the test tube and observe the number of green spots. Set up a blank control 2 according to the non-contact sterilization test.

[0107] The test results are shown in Table 1.

[0108] Table 1

[0109]

[0110] Table 2

[0111]

[0112] Table 3

[0113]

[0114] Table 4

[0115]

[0116] Table 5

[0117]

[0118] Table 6

[0119]

[0120] Table 7

[0121]

[0122] Table 8

[0123]

[0124] As can be seen from Tables 1 to 5, the antibacterial and sterilization effects of the ceramic tiles of Examples 1 to 5 are good. The contact and non-contact sterilization rates of the nine areas can reach more than 80%. Among them, in the contact sterilization test, at least 6 of the nine areas can achieve a sterilization rate of 100%, and the remaining areas can still achieve a sterilization rate of more than 85%. This shows that the antibacterial ceramic tiles produced by the present invention have high production stability and good sterilization effect. Figure 1 、 Figure 2 As shown, the scanning electron microscope image of the nanosilver prepared in Example 2 shows that the nanosilver structure prepared by the formulation process of the present invention is a dispersed spherical structure with pores.

[0125] As shown in Table 6, sodium citrate was not added to the antibacterial agent of Comparative Example 1, and the obtained nanosilver scanning electron microscope image is as follows: Figure 3 The nanosilver dispersion prepared in Comparative Example 1 was added to the base glaze to produce ceramic tiles with poor antibacterial effect on the surface, with only one of the nine parallel samples having a bactericidal effect.

[0126] As shown in Table 7, in the preparation of the antibacterial agent in Comparative Example 2, the catechin was first mixed with sodium citrate, which affected the reaction between the catechin and silver nitrate. Consequently, the porous, spiny spheres of silver nanoparticles could not be successfully synthesized. Only two of the nine replicates showed a bactericidal effect.

[0127] It can be seen from Table 8 that the ceramic tile of Comparative Example 3 directly uses the basic glaze without adding an antibacterial agent, and the fired ceramic tile surface has no antibacterial effect.

[0128] Example 6

[0129] The nanosilver dispersion prepared in Example 2 was diluted to 50 mg / L, 100 mg / L, 120 mg / L and 150 mg / L, respectively. The antibacterial range of the nanosilver dispersion was tested. The results are shown in Table 9 and Figure 4 shown.

[0130] Table 9

[0131]

[0132] As shown in Table 9, the antibacterial range of the nanosilver dispersion provided by the present invention gradually increases with increasing concentration.

[0133] Example 7

[0134] The antibacterial range of 120 mg / L and 150 mg / L nanosilver dispersions was tested under constant temperature incubation at 23°C (room temperature). The results are shown in Table 10 and Figure 5 shown.

[0135] Table 10

[0136]

[0137] Table 10 shows that the bactericidal effect of the nanosilver dispersion provided by the present invention is not limited to contact sterilization; it also exhibits non-contact antibacterial activity, and this non-contact antibacterial activity has a specific range. The results show that the nanosilver dispersion exhibits a wider zone of inhibition at 37°C than at 23°C (room temperature). This indicates that increasing temperature enhances the antibacterial effect of the nanosilver provided by the present invention. Therefore, using the antibacterial glaze provided by the present invention with products such as heating tiles can further enhance their antibacterial effect.

[0138] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made by using the contents of the present invention specification under the inventive concept of the present invention, or direct / indirect application in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A bacteriostatic agent, characterized in that The antibacterial agent is a nano-silver dispersion in the shape of a porous spherical ball; the preparation method of the nano-silver dispersion comprises the following steps: S1. Mix the silver nitrate solution and the first reducing agent solution and stir them in the dark for 18 to 24 hours; S2, adding a second reducing agent to the mixed solution of step S1, mixing and stirring, and reacting in the dark for 7 to 10 days to obtain the nanosilver dispersion; The first reducing agent is catechin; The second reducing agent is sodium citrate; The molar ratio of the silver nitrate to the first reducing agent is 1.45:1; The molar ratio of the silver nitrate to the second reducing agent is 1.85:

1.

2. The antibacterial agent according to claim 1, characterized in that The concentration of the silver nitrate solution is 1-1.7 g / L.

3. The antibacterial agent according to claim 1, characterized in that The concentration of the first reducing agent solution is 1.18-2.00 g / L.

4. An antibacterial glaze, characterized in that The invention comprises a basic glaze and the antibacterial agent according to any one of claims 1 to 3; based on the total weight of the basic glaze being 100%, the added amount of the antibacterial agent is 5 to 10%. 5.An antibacterial tile, characterized in that: It comprises at least a body layer and a surface glaze layer, and the surface glaze layer is fired using the antibacterial glaze according to claim 4.

6. A method for preparing antibacterial tiles according to claim 5, characterized in that: The steps include: A. dry-mixing and ball-milling the basic glaze according to the formula of the basic glaze to obtain a basic glaze; B. adding the antibacterial agent to the basic glaze to obtain the antibacterial glaze; C. Applying the antibacterial glaze to the surface of the ceramic tile body, drying it, and then firing it in a kiln. After polishing, the antibacterial ceramic tile is obtained.

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