Ceramic product with antibacterial property and preparation method thereof

Abstract

The invention relates to the technical field of ceramic products, and discloses an antibacterial ceramic product and a preparation method thereof.The antibacterial ceramic product comprises a ceramic matrix, an antibacterial glaze layer applied to the surface of the matrix and a chitosan-titanium dioxide composite sol film coated on the glaze layer, and zirconium phosphate serves as a carrier; the metal ion effect and the chitosan-titanium dioxide composite film are synergistically compounded under the photocatalysis effect, the prepared composite antibacterial and self-cleaning ceramic material realizes the double-effect synergy of'rapid film breaking-continuous sterilization ', chitosan is carbonized in situ to form a nitrogen-doped carbon layer, visible light response is expanded, a Si-O-C chemical bonding interface is constructed, and the composite antibacterial and self-cleaning ceramic material is prepared. The three technical bottlenecks that a ceramic product is weak in antibacterial property in a dark environment, the visible light utilization rate is low and a coating film is easy to fall off are broken through, and the antibacterial function with a self-cleaning function is provided.

Description

Technical Field

[0001] The present invention relates to the technical field of ceramic products, in particular to an antibacterial ceramic product and a preparation method thereof. Background Art

[0002] Ceramic products are widely used in architectural sanitary ware, household tableware, medical devices, and other fields due to their excellent physical and chemical properties, aesthetic appeal, and ease of cleaning. However, ceramic surfaces themselves lack significant antimicrobial properties, making them a vulnerable breeding ground for microorganisms such as bacteria and mold. This poses a health and safety risk, particularly in humid environments or in settings with frequent contact (such as kitchens, bathrooms, and hospitals). Therefore, the development of functional ceramic products with long-lasting, highly effective antimicrobial properties is of great practical significance and application value.

[0003] At present, there are two main technical approaches to impart antibacterial properties to ceramic products:

[0004] Antibacterial glaze technology is achieved by adding inorganic antibacterial agents (such as silver ions (Ag) + ), copper ions (Cu 2 + ), zinc ions (Zn 2+ ) or its compounds) or photocatalytic antibacterial agents (such as titanium dioxide, TiO2). During the firing process, these antibacterial agents are fixed in the glaze layer structure.

[0005] Metal ion antimicrobial agents have a potential risk of ion dissolution (especially silver ions, which are expensive and may cause environmental or health concerns due to dissolution), their antimicrobial spectrum may be limited, and their antimicrobial effect may decay after long-term use due to consumption of active sites.

[0006] Photocatalytic antimicrobial agents, such as TiO2, require ultraviolet (UV) irradiation to stimulate the production of highly oxidizing reactive oxygen species (ROS) to achieve sterilization. Their antimicrobial effectiveness is significantly reduced or even lost in indoor or low-light environments. Using TiO2 alone in the glaze layer can also reduce its photocatalytic efficiency due to the glaze's glassy encapsulation and high-temperature firing. Summary of the Invention

[0007] In response to the shortcomings of the existing technology, the present invention provides a ceramic product with antibacterial properties and a preparation method thereof. By using zirconium phosphate as a carrier, the effect of metal ions and the chitosan-titanium dioxide composite film are synergistically compounded under the photocatalytic effect, breaking through the three major technical bottlenecks of ceramic products' weak antibacterial properties in dark environments, low visible light utilization, and easy detachment of the coating, and providing an antibacterial property with self-cleaning function.

[0008] A ceramic product with antibacterial properties comprises a ceramic substrate, an antibacterial glaze layer applied to the surface of the substrate, and a chitosan-titanium dioxide composite sol film coated on the glaze layer. The preparation method of the ceramic product with antibacterial properties is as follows:

[0009] Step 1: Apply the antibacterial glaze to the ceramic body, let it stand for 8-10 hours, and then fire it according to the ceramic process;

[0010] Step 2: Immerse the fired ceramic into chitosan-titanium dioxide composite sol, pull it at a speed of 6-12 cm / min, dry it at 60-80°C for 10-20 minutes after immersion, repeat the immersion-drying 3-4 times, and calcine it at 350-400°C for 1-3 hours to obtain a ceramic product with antibacterial properties.

[0011] Furthermore, in step (2), the film thickness is controlled to be 20-75 nm after repeated pulling and coating.

[0012] Furthermore, the antibacterial glaze layer is composited by a glaze with a mass ratio of (95-105):3 and zirconium phosphate-loaded silver-copper antibacterial powder.

[0013] Furthermore, the preparation process of zirconium phosphate-supported silver-copper antibacterial powder is as follows:

[0014] Step 1: Add 2 L of a 0.5 mol / L zirconium oxychloride aqueous solution to a 1.2 mol / L phosphoric acid solution to generate a zirconium phosphate colloid, which is filtered and washed until neutral, and then dried at 110-120° C.

[0015] Step 2: Add (1-3) g of Li2CO3 to 100 g of zirconium phosphate colloid, calcine the mixture at 900-1400° C. to form a powder, and then reduce the calcination temperature to 900-1200° C. to obtain a zirconium phosphate support;

[0016] Step 3, using zirconium phosphate as a carrier to load silver ions and copper ions, wherein the molar ratio of silver ions to copper ions is 1:(2.9-3.1);

[0017] Step 4: calcining the metal ion-loaded zirconium phosphate at 450-460° C. for 2-4 hours, and grinding the mixture to pass through a 280-290 mesh sieve.

[0018] Furthermore, the preparation method of chitosan-titanium dioxide composite sol is as follows:

[0019] Chitosan acetic acid solution with a mass concentration of 1-5% is mixed with nano-TiO2 powder with a particle size of 10-50 nm, citric acid is added, and the mixture is mechanically stirred for 0.5-1 h and then ultrasonically treated for 1-2 h to obtain a liquid sol.

[0020] Furthermore, the mass ratio of the chitosan solution, the cross-linking agent and TiO2 in the step is 100:(1-5):(10-30).

[0021] Beneficial technical effects

[0022] After carbonization, chitosan forms a nitrogen-doped carbon layer that wraps around TiO2 nanoparticles. Nitrogen atoms replace oxygen sites in the TiO2 lattice to form Ti-N bonds. The band gap increases from 3.2eV to 2.8eV, and the visible light absorption rate is increased to more than 2.3 times that of traditional TiO2 films. The carbon layer acts as an electron conductor, accelerating the extraction of photogenerated electrons (the electron mobility is increased by 10 times). Therefore, the response range is extended to the visible light region, and the utilization rate of sunlight is increased to more than 30%. Under visible light, the antibacterial ability is improved. At the same time, when Ag + :Cu 2+ When it is about 4:1, 4 times Ag + The concentration causes membrane proteins to denature rapidly, forming 2~5nm holes. 2+ Through the pores, it directly hits the target inside the cell. 2+ Supplement Ag + In order to address the shortcomings of anaerobic bacteria / fungi, the bimetallic system significantly improves the fungal killing rate. At the same time, the zirconium phosphate carrier matches the dual ion release rate. Using zirconium phosphate as a carrier, the metal ion effect and the chitosan-titanium dioxide composite film are synergistically combined in the photocatalytic effect. The prepared composite antibacterial and self-cleaning ceramic material has better effect.

[0023] The carbonized product of chitosan forms a chemical bond with the glaze layer, and the carboxyl group (-COOH) in the carbon layer reacts with the SiO2 in the glaze layer to prevent the TiO2 film from peeling off and improve the adhesion by more than 50%. DETAILED DESCRIPTION

[0024] Example 1

[0025] A ceramic product with antibacterial properties, the preparation method of which is as follows:

[0026] Step 1: add 2 L of 0.5 mol / L zirconium oxychloride aqueous solution to 1.2 mol / L phosphoric acid solution to generate zirconium phosphate colloid, filter and wash until neutral, and then dry at 120°C;

[0027] Step 2: Add 2 g of Li2CO3 to 100 g of zirconium phosphate colloid, calcining the mixture at 1000 ° C into a powder, reducing the calcination temperature to 900 ° C, and using 100 g of zirconium phosphate as a carrier to load 3 g of silver ions and copper ions with a molar ratio of 1:3. The metal ion-loaded zirconium phosphate is calcined at 450 ° C for 3 h and ground through a 280-mesh sieve to obtain an antibacterial glaze;

[0028] Step 3: applying the antibacterial glaze to the ceramic body, leaving it to stand for 9 hours, and firing it according to the ceramic process;

[0029] Step 4: 100 g of a 3% chitosan acetic acid solution was mixed with 20 g of a 30 nm nano-TiO2 powder, 3 g of citric acid was added, and the mixture was mechanically stirred for 0.5 h and then ultrasonically treated for 1 h to obtain a liquid sol;

[0030] Step 5: Immerse the fired ceramic into chitosan-titanium dioxide composite sol, pull it at a speed of 8 cm / min, dry it at 70°C for 15 minutes after immersion, repeat the immersion-drying three times, and calcine it at 380°C for 2 hours. After coating, the film thickness is controlled at 60 nm to obtain a ceramic product with antibacterial properties.

[0031] Example 2

[0032] A ceramic product with antibacterial properties, the preparation method of which is as follows:

[0033] Step 1: add 2 L of 0.5 mol / L zirconium oxychloride aqueous solution to 1.2 mol / L phosphoric acid solution to generate zirconium phosphate colloid, filter and wash until neutral, and then dry at 115°C;

[0034] Step 2: Add 2 g of Li2CO3 to 100 g of zirconium phosphate colloid, calcinate the mixture at 1200 ° C to form a powder, reduce the calcination temperature to 1000 ° C, and use 95 g of zirconium phosphate as a carrier to load 3 g of silver ions and copper ions with a molar ratio of 1:2.9. The metal ion-loaded zirconium phosphate is calcined at 450 ° C for 2 h and ground through a 280-mesh sieve to obtain an antibacterial glaze;

[0035] Step 3: applying the antibacterial glaze to the ceramic body, leaving it to stand for 8 hours, and firing it according to the ceramic process;

[0036] Step 4: 100 g of a chitosan acetic acid solution having a mass concentration of 1% was mixed with 10 g of a nano-TiO2 powder having a particle size of 50 nm, 5 g of citric acid was added, and the mixture was mechanically stirred for 0.5 h and then ultrasonically treated for 1 h to obtain a liquid sol;

[0037] Step 5: Immerse the fired ceramic in chitosan-titanium dioxide composite sol, pull it at a speed of 12 cm / min, dry it at 80°C for 20 minutes after immersion, repeat the immersion-drying three times, and calcine it at 350°C for 1 hour. After coating, the film thickness is controlled at 75 nm to obtain a ceramic product with antibacterial properties.

[0038] Example 3

[0039] A ceramic product with antibacterial properties, the preparation method of which is as follows:

[0040] Step 1: add 2 L of 0.5 mol / L zirconium oxychloride aqueous solution to 1.2 mol / L phosphoric acid solution to generate zirconium phosphate colloid, filter and wash until neutral, and then dry at 120°C;

[0041] Step 2: Add 3 g of Li2CO3 to 100 g of zirconium phosphate colloid, calcining the mixture at 1400 ° C into a powder, reducing the calcination temperature to 1200 ° C, and using 105 g of zirconium phosphate as a carrier to load 3 g of silver ions and copper ions with a molar ratio of 1:3.1. The metal ion-loaded zirconium phosphate is calcined at 460 ° C for 4 hours and ground through a 290 mesh sieve to obtain an antibacterial glaze;

[0042] Step 3: applying the antibacterial glaze to the ceramic body, leaving it to stand for 8 hours, and firing it according to the ceramic process;

[0043] Step 4: 100 g of a 1% chitosan acetic acid solution was mixed with 10 g of a 10 nm nano-TiO2 powder, 1 g of citric acid was added, and the mixture was mechanically stirred for 0.5 h and then ultrasonically treated for 1 h to obtain a liquid sol;

[0044] Step 5: Immerse the fired ceramic into chitosan-titanium dioxide composite sol, pull it at a speed of 6 cm / min, dry it at 60°C for 10 minutes after immersion, repeat the immersion-drying three times, and bake it at 350°C for 1-3 hours. After coating, the film thickness is controlled at 20 nm to obtain a ceramic product with antibacterial properties.

[0045] Example 4

[0046] A ceramic product with antibacterial properties, the preparation method of which is as follows:

[0047] Step 1: add 2 L of 0.5 mol / L zirconium oxychloride aqueous solution to 1.2 mol / L phosphoric acid solution to generate zirconium phosphate colloid, filter and wash until neutral, and then dry at 110°C;

[0048] Step 2: Add 1 g of Li2CO3 to 100 g of zirconium phosphate colloid, calcining the mixture at 900° C. into a powder, reducing the calcination temperature to 900° C., and using 95 g of zirconium phosphate as a carrier to load 3 g of silver ions and copper ions with a molar ratio of 1:2.9. The metal ion-loaded zirconium phosphate is calcined at 450° C. for 2 h, and ground through a 280-mesh sieve to obtain an antibacterial glaze.

[0049] Step 3: applying the antibacterial glaze to the ceramic body, leaving it to stand for 10 hours, and firing it according to the ceramic process;

[0050] Step 4: 100 g of 5% chitosan acetic acid solution was mixed with 30 g of 50 nm nano-TiO2 powder, 5 g of citric acid was added, and the mixture was mechanically stirred for 1 h and then ultrasonically treated for 2 h to obtain a liquid sol;

[0051] Step 5: Immerse the fired ceramic in chitosan-titanium dioxide composite sol, pull it at a speed of 12 cm / min, dry it at 80°C for 20 minutes after immersion, repeat the immersion-drying 4 times, and calcine it at 400°C for 3 hours. After coating, the film thickness is controlled at 75 nm to obtain a ceramic product with antibacterial properties.

[0052] Detailed acceptance test plan for antibacterial ceramic products:

[0053] 1. Experimental Purpose

[0054] A comprehensive and detailed acceptance test was conducted on the antibacterial ceramic products prepared in Examples 1-4. Through detailed experiments and testing processes, it was accurately verified whether their antibacterial properties, glaze quality, film properties, etc. met the expected standards to ensure that the product quality met the requirements.

[0055] 2. Experimental Materials and Equipment

[0056] (1) Experimental materials

[0057] 5-10 pieces of ceramic products with antibacterial properties prepared in Examples 1-4 (ensure that there is sufficient sample size for each experimental project and that repeated experiments can be performed).

[0058] Standard experimental strains: Escherichia coli ATCC25922, Staphylococcus aureus ATCC25923, etc. obtained from professional strain collection institutions to ensure that the strain activity and purity meet the experimental requirements.

[0059] Culture medium: Nutrient agar medium (for colony culture and counting) and broth medium (for bacterial activation and proliferation) should be prepared accurately according to the culture medium instructions and sterilized by high pressure (121°C, 15-20 minutes) before use.

[0060] Chemical reagents:

[0061] Physiological saline: 0.85% sodium chloride solution, used to dilute bacterial suspension and wash samples, and stored after high-pressure sterilization (121°C, 15 minutes).

[0062] Sterile water: used for preparing solutions and dilution operations, also sterilized by high pressure.

[0063] Ethanol: 75% volume fraction, used for sample surface disinfection. The concentration must be checked before use.

[0064] Chitosan, acetic acid, nano-TiO2, citric acid and other raw materials: Select raw materials from the same batch as those used to prepare ceramic products to ensure the accuracy of ingredient consistency verification. Store in a dry and cool place to avoid moisture and deterioration.

[0065] 3M tape: Used for film adhesion testing. 3M tape should be selected to meet the cross-cut test standards to ensure stable adhesion and free of impurities.

[0066] (2) Experimental equipment

[0067] Constant temperature incubator: Choose a model with precise temperature control (accuracy ±0.5°C) and humidity adjustment functions. Calibrate and verify performance before use to ensure that temperature uniformity meets requirements.

[0068] Biosafety cabinet: Class II biosafety cabinet, equipped with a high-efficiency air filtration system, undergoes wind speed detection and ultraviolet disinfection before use to ensure a safe and sterile operating environment.

[0069] Electronic balance: with an accuracy of 0.0001g, used for precise weighing of experimental materials and samples. Regular calibration and maintenance are required to ensure weighing accuracy.

[0070] Microscope: An optical microscope equipped with objective lenses of different magnifications (e.g., 10×, 40×, 100×), and a scanning electron microscope (SEM) are used for high-resolution observation of the microstructure of thin films and glazes. Check the lens cleanliness and focusing performance before use.

[0071] Spectrophotometer: The wavelength range covers the visible light region (380-780nm), with high-precision measurement capabilities. Regular wavelength calibration and absorbance calibration are performed to ensure accurate measurement of film thickness and transmittance.

[0072] Hardness tester: Use Rockwell hardness tester or Vickers hardness tester, select appropriate test scale and indenter according to the hardness range of ceramic products, and calibrate the hardness block before use to ensure reliable test results.

[0073] Ultrasonic cleaner: frequency is adjustable (generally 40kHz), power is stable, used for sample cleaning and ultrasonic treatment of liquid sols. When in use, adjust the cleaning time and power parameters according to the properties of the sample and sol.

[0074] High-temperature furnace: The maximum temperature can meet the firing temperature requirements of ceramic products (such as 1500℃), and it has a programmed temperature rise function, which can accurately control the heating rate, holding time and cooling process. Temperature uniformity testing and calibration are carried out before use.

[0075] 3. Experimental steps

[0076] (1) Antibacterial performance test

[0077] Strain preparation

[0078] Obtain a small amount of frozen bacterial strains from a culture collection institution under sterile conditions using a sterile inoculating loop and inoculate it into the broth culture medium.

[0079] Place the inoculated broth culture medium in a 37°C constant temperature incubator and culture for 18-24 hours. During this period, observe the growth of the bacteria. If the culture medium becomes turbid, it means that the bacteria have entered the logarithmic growth phase.

[0080] Take an appropriate amount of cultured bacterial solution and perform gradient dilution (e.g. 10 -1 , 10 -2 , 10 -3 Select appropriate dilution of bacterial solution for viable bacteria count and determine the concentration of bacterial suspension to reach about 1×10 6 CFU / mL.

[0081] Sample processing:

[0082] Use a sterile scalpel to cut the ceramic product into small pieces of 1 cm × 1 cm, and avoid contamination of the sample surface during the cutting process.

[0083] Place the cut sample pieces in a sterile culture dish, pour in an appropriate amount of 75% ethanol, soak for 5-10 minutes for surface disinfection, remove the ethanol with a sterile pipette, add sterile saline, rinse the sample three times, soaking for 2-3 minutes each time to remove residual ethanol and surface impurities, place the cleaned sample pieces on sterile filter paper, and dry them in a sterile environment for later use.

[0084] Inoculation and cultivation:

[0085] In a biosafety cabinet, pour sterile nutrient agar medium into sterile culture dishes, about 15-20 mL per dish. After the culture medium solidifies, mark them as experimental and control groups. Use sterile tweezers to evenly place small pieces of processed ceramic samples on the surface of the experimental group culture medium, with 3-5 samples placed in each culture dish.

[0086] Use a sterile pipette to draw 100 μL of the solution with a concentration of approximately 1 × 10 6 A bacterial suspension of 100 μL / mL was evenly spread on the surface of the culture medium containing the ceramic sample to ensure uniform coverage; the culture dish of the control group did not contain any ceramic sample, and 100 μL of bacterial suspension was also aspirated for coating; the culture dishes of the experimental and control groups were placed in a 37°C constant temperature incubator and cultured for 24 hours. During the culture process, the humidity in the incubator was kept stable to prevent the culture medium from drying out and affecting the growth of the colonies.

[0087] Observation and analysis of results:

[0088] After the incubation period, remove the culture dish and place it in a biosafety cabinet. Use a colony counter to count the colonies in the dish. For dishes with dense colonies, the grid method can be used for estimation.

[0089] Calculate the antibacterial rate of the ceramic products of each example against Escherichia coli and Staphylococcus aureus using the following formula: Antibacterial rate (%) = (Number of colonies in the blank control group - Number of colonies in the sample group) / Number of colonies in the blank control group × 100%. Perform three replicates of each example, and calculate the average and standard deviation of the antibacterial rate to assess the stability of the antibacterial performance. If any experimental result deviates significantly from the average (e.g., more than 20%), analyze the cause and repeat the experiment.

[0090] (2) Glaze quality inspection:

[0091] Appearance inspection:

[0092] Place the ceramic product on a white background under natural light or a standard light source (such as D65 light source), keep the observation distance at 30-50 cm, and observe with normal vision or wearing corrective glasses.

[0093] Carefully inspect the glaze for uniform color and color variations; smoothness and unevenness; and defects such as bubbles, cracks, and pinholes. Minor defects can be observed with the aid of a magnifying glass (10-20x magnification). Record the type, location, and number of all defects observed and create a defect distribution map for subsequent analysis and evaluation.

[0094] Hardness test:

[0095] Select different areas of the ceramic glaze (such as edges, centers, corners, etc.), and select 5 test points in each area. The distance between the test points should be greater than 2mm to avoid mutual influence between the test points. According to the hardness range of the ceramic product, select an appropriate hardness tester scale (such as Rockwell hardness HRA, HRB or Vickers hardness HV) and indenter type. Align the indenter of the hardness tester vertically with the test point, apply the specified test force (such as 60kgf for Rockwell hardness HRA, and the test force for Vickers hardness HV should be selected according to the hardness of the sample), maintain the test force for the specified time (such as 10-15 seconds), and then remove the test force.

[0096] Read the hardness value displayed on the durometer and record each test result. Calculate the average and standard deviation of the hardness values ​​at the five test points to assess the uniformity and stability of the glaze hardness. If the hardness values ​​fluctuate significantly, further inspection is required to determine whether the test points are appropriate or whether the sample has internal structural inhomogeneities.

[0097] Microstructure observation:

[0098] Use cutting equipment to cut the ceramic products into thin slices perpendicular to the glaze surface. Be careful to avoid deformation and damage of the samples during the cutting process. Grind and polish the cut slices to make their surface flat and smooth, and control the thickness to about 0.1-0.2mm.

[0099] For optical microscopy, place the polished section on a glass slide, add a drop of anhydrous ethanol, cover with a coverslip, and remove any bubbles before observation. Observe the crystal structure, grain size, and distribution of the glaze surface at different magnifications (e.g., 10×, 40×). Take at least five photographs from different fields of view and record your observations.

[0100] For scanning electron microscopy (SEM) observation, the polished slices were gold-sprayed (approximately 10-20 nm thick) to improve the sample's conductivity. The treated samples were placed on the SEM stage, and the glaze microstructure was observed at different magnifications (e.g., 500×, 5000×). High-resolution photographs were taken to analyze the glaze's micromorphological features, such as grain boundaries and pore distribution.

[0101] (3) Film performance testing

[0102] Thickness measurement:

[0103] Use the film thickness measurement function of the spectrophotometer and select the appropriate measurement mode (such as reflection or transmission, determined according to the properties of the film and the characteristics of the instrument). Evenly select 5-10 measurement points on the surface of the ceramic film. The measurement points should be distributed in different areas and avoid being concentrated in the same location. Align the probe of the spectrophotometer vertically with the measurement points, ensuring that the probe is in close contact with the film surface. Read and record the film thickness value at each measurement point.

[0104] Calculate the mean and standard deviation of the thickness values ​​at the measurement points to determine whether the film thickness falls within the ranges specified in the examples (60 nm for Example 1, 75 nm for Example 2, 20 nm for Example 3, and 75 nm for Example 4). If the thickness deviation is significant, verify the correctness of the measurement method, probe calibration, or any issues with the film preparation process.

[0105] Light transmittance test:

[0106] Set the spectrophotometer wavelength to 550nm (a representative wavelength in the visible light region) and perform wavelength calibration to ensure wavelength accuracy. Place an uncoated ceramic blank in the sample cell as a blank control sample for baseline calibration to eliminate the influence of the ceramic matrix on transmittance. Place the coated ceramic in the sample cell and measure its transmittance at 550nm. Measure each sample three times, and take the average value as the final result. Analyze the film transmittance data to evaluate the film's optical properties. Low transmittance may be related to the film's composition, thickness, uniformity, or internal defects, requiring further microstructural observation and analysis.

[0107] Surface morphology observation:

[0108] Similar to the observation of glaze microstructure, for optical microscope observation, the surface of the ceramic film is simply cleaned, placed on a glass slide, a drop of anhydrous ethanol is added, and a coverslip is placed. The flatness, smoothness and obvious defects of the film surface are observed, and photos are taken to record the observation results.

[0109] For scanning electron microscope (SEM) observation, the ceramic product was gold-sprayed and placed on the SEM sample stage. The microscopic morphology of the film surface was observed at different magnifications (such as 1000×, 10000×), and the particle distribution, pore structure and other characteristics of the film surface were analyzed. High-resolution photos were taken for detailed analysis.

[0110] Adhesion test:

[0111] Use a scribing knife to create a 1mm x 1mm grid on the film surface. Keep the knife perpendicular to the film surface and apply even force to ensure the scratch depth reaches the ceramic substrate surface. Create a total of 10 x 10 = 100 squares.

[0112] Take a piece of 3M tape, slightly longer than the cutout area, and apply it evenly to the cutout surface. Press firmly from one end of the tape to the other with your fingers or a rubber roller to remove any air between the tape and the film, ensuring a tight fit. Keep the tape attached for 1-2 minutes, then quickly (within 1-2 seconds) remove it perpendicular to the film surface. Observe the film shedding in the cutout area and rate it according to ISO 2409. Grade 0 indicates no film shedding; Grade 1 indicates some film shedding at the cutout intersection, but the shedding area does not exceed 5%; Grade 2 indicates some film shedding along the cutout edge, with a shedding area between 5% and 15%; Grade 3 indicates a shedding area between 15% and 35%; Grade 4 indicates a shedding area between 35% and 65%; and Grade 5 indicates a shedding area exceeding 65%. Record the adhesion grade for each sample to assess the bond strength between the film and the ceramic substrate.

[0113] (IV) Verification of liquid sol composition

[0114] Raw material weighing verification:

[0115] According to the formulation of the liquid sol in each example, use an electronic balance to accurately weigh the chitosan acetic acid solution, nano-TiO2 powder, citric acid, and other raw materials. For liquid raw materials (such as chitosan acetic acid solution), use a pipette or graduated cylinder to accurately measure, and make sure to keep your line of sight level with the scale line during the measurement process to ensure the measured volume is accurate. After weighing or measuring, record the actual weighed or measured value, compare it with the theoretical value of the formulation in the example, and calculate the error range. If the error exceeds ±5% (the error standard can be adjusted according to actual conditions), it is necessary to check the accuracy of the weighing equipment, the standard operation process, and whether the raw materials have absorbed moisture or volatilized, and re-weigh or measure.

[0116] Preparation process validation:

[0117] According to the preparation method of the liquid sol in each embodiment, the raw materials accurately weighed or measured are added into a clean container in sequence. First, the chitosan acetic acid solution is poured into the container, followed by the nano-TiO2 powder, and finally the citric acid.

[0118] Use a mechanical stirrer to stir the sol at a speed of 300-500 rpm (adjust according to the sol viscosity and stirring effect) for 0.5 hours. Observe the sol's state during stirring, such as whether it is evenly dispersed and whether there are any agglomerations. Record the stirring process. After stirring, transfer the sol to an ultrasonic cleaner. Set the ultrasonic frequency to 40 kHz and the power to 200-300 W (adjust according to the sol properties and ultrasonic effect) for 1 hour. Observe the dispersion and stability of the sol during the ultrasonic process, such as whether there is precipitation or stratification, and record the ultrasonic process.

[0119] Compare the prepared sol with the sol described in the examples in terms of color, transparency, viscosity, and other aspects to determine whether the preparation process meets the requirements. If there are significant differences in the sol properties, analyze the impact of factors such as raw material quality, stirring speed, and ultrasonic parameters on the sol preparation and make corresponding adjustments and optimizations.

[0120] (V) High temperature stability test:

[0121] The ceramic products of each embodiment were placed in a high-temperature furnace, ensuring that there was a certain distance between the ceramic products (about 2-3 cm) to avoid contact with each other and affecting the uniformity of heating; the high-temperature furnace was set to a heating program, and heated to the highest temperature in the ceramic firing process (1000°C for Example 1, 1200°C for Example 2, 1400°C for Example 3, and 900°C for Example 4) at a heating rate of 5°C / min. During the heating process, the temperature changes in the furnace were monitored in real time to ensure a stable heating rate.

[0122] When the temperature reaches the set maximum temperature, it is kept warm for a certain period of time (the holding time in Example 1 refers to the relevant parameters of its firing process, and the same applies to other embodiments). During the holding process, the temperature fluctuation range in the furnace is kept within ±10°C; after the holding period is completed, the power supply of the high-temperature furnace is turned off, and the ceramic products are allowed to cool naturally in the furnace. Avoid opening the furnace door during the cooling process to prevent the ceramic products from cracking due to a sudden drop in temperature.

[0123] After the ceramic product has cooled to room temperature, remove it and observe any changes in appearance, such as cracking of the glaze, peeling of the film, or color change. Use a microscope to observe microstructural changes in the glaze and film, analyze the effects of high-temperature treatment on the performance of the ceramic product, and assess its high-temperature stability.

[0124] IV. Recording and Analysis of Experimental Results

[0125] (1) Antibacterial performance test results

[0126] The antibacterial performance of the ceramic products of Examples 1-4 was tested, and Escherichia coli and Staphylococcus aureus were selected as the test bacteria, and the concentration of the bacterial suspension was 1×10 6 CFU / mL, the incubation time is 24 hours. In the three groups of tests on Escherichia coli in Example 1, the colony counts of the control groups were 320, 315, and 300, respectively, and the colony counts of the sample groups were 12, 15, and 10, respectively. The calculated antibacterial rates were 96.25%, 95.24%, and 96.67%, respectively, with an average antibacterial rate of 95.88%; the antibacterial rates of the Staphylococcus aureus tests were 96.67%, 96.33%, and 96.00%, respectively, with an average antibacterial rate of 96.33%.

[0127] The antibacterial rates of Example 2 against Escherichia coli were 93.94%, 93.23%, and 92.62%, respectively, with an average antibacterial rate of 93.26%. The average antibacterial rate against Staphylococcus aureus was 94.19%. The average antibacterial rate against Escherichia coli in Example 3 reached 97.04%, and the average antibacterial rate against Staphylococcus aureus was 97.97%. The average antibacterial rate against Escherichia coli in Example 4 was 94.15%, and the average antibacterial rate against Staphylococcus aureus was 95.00%.

[0128] (2) Film thickness measurement results

[0129] In the film thickness measurement, Example 1 selected three measurement points, which were located at the upper left corner, upper right corner, and lower left corner of the sample, respectively. The measured thickness values ​​were 58nm, 62nm, and 61nm, respectively. The calculated average value was 60.33nm and the standard deviation was 1.53. The measured thickness values ​​of Example 2 were 73nm, 76nm, and 75nm, respectively, with an average value of 74.67nm. The measured values ​​of Example 3 were 19nm, 22nm, and 20nm, with an average value of 20.33nm, a standard deviation of 1.53, and a coefficient of variation of 7.52%. The average measured thickness of Example 4 was 74.67nm, which was close to the set value of 75nm.

[0130] (3) Statistical analysis and performance evaluation

[0131] Performance stability was evaluated by calculating the mean, standard deviation, and coefficient of variation for the antibacterial rate and film thickness of each example. In terms of antibacterial performance, Example 3 had the smallest standard deviation, indicating the best antibacterial stability. Example 2 had a relatively large standard deviation for its antibacterial rate against E. coli, indicating slightly weaker stability. Regarding film thickness, Examples 1, 2, and 4 had a small coefficient of variation, indicating good thickness uniformity, while Example 3 had a large coefficient of variation, indicating that thickness uniformity needs improvement.

[0132] (IV) Acceptance judgment and cause analysis

[0133] The qualified standards are set as an antibacterial rate of not less than 95% and a film thickness within the range of ±5% of the set value. The antibacterial rates of Examples 1, 3, and 4 against Staphylococcus aureus and the antibacterial rates of Examples 1 and 3 against Escherichia coli all meet the standards; however, the antibacterial rate of Example 2 against Escherichia coli does not meet the standards, which may be due to the volatilization of some antibacterial metal ions during high-temperature calcination at 1200°C, resulting in insufficient actual antibacterial component loading. In terms of film thickness, Examples 1, 2, and 4 meet the requirements. Although the average thickness of Example 3 is within the standard range, the coefficient of variation is too large. It is speculated that the pulling speed of 6 cm / min is too slow, which makes the immersion time of the ceramic in the sol unstable, affecting the uniform formation of the film.

[0134] Comparative Example 1

[0135] The traditional antibacterial ceramic products are prepared by:

[0136] Step 1: Apply the glaze to the ceramic body, let it stand for 9 hours, and then fire it according to the ceramic process;

[0137] Step 2: Immerse the fired ceramic in titanium dioxide sol, pull it up at a speed of 8 cm / min, dry it at 70°C for 15 minutes after dipping, repeat the dipping-drying process 3 times, and bake it at 380°C for 2 hours. After coating, the film thickness is controlled at 60 nm to obtain a ceramic product.

[0138] Comparative Example 2

[0139] The traditional antibacterial ceramic products are prepared by:

[0140] Step 1: applying the antibacterial glaze to the ceramic body, leaving it to stand for 9 hours, and firing it according to the ceramic process;

[0141] Step 2: 100 g of a 3% chitosan acetic acid solution was mixed with 20 g of a 30 nm nano-TiO2 powder, 3 g of citric acid was added, and the mixture was mechanically stirred for 0.5 h and then ultrasonically treated for 1 h to obtain a liquid sol;

[0142] Step 3: Immerse the fired ceramic into chitosan-titanium dioxide composite sol, pull it at a speed of 8 cm / min, dry it at 70°C for 15 minutes after immersion, repeat the immersion-drying process 3 times, and calcine it at 380°C for 2 hours. After coating, the film thickness is controlled at 60 nm to obtain a ceramic product with antibacterial properties.

[0143] Comparative Example 3

[0144] The traditional antibacterial ceramic products are prepared by:

[0145] Step 1: add 2 L of 0.5 mol / L zirconium oxychloride aqueous solution to 1.2 mol / L phosphoric acid solution to generate zirconium phosphate colloid, filter and wash until neutral, and then dry at 120°C;

[0146] Step 2: Add 2 g of Li2CO3 to 100 g of zirconium phosphate colloid, calcining the mixture at 1000 ° C into a powder, reducing the calcination temperature to 900 ° C, and using 100 g of zirconium phosphate as a carrier to load 3 g of silver ions and copper ions with a molar ratio of 1:3. The metal ion-loaded zirconium phosphate is calcined at 450 ° C for 3 h and ground through a 280-mesh sieve to obtain an antibacterial glaze;

[0147] Step 3: Apply the antibacterial glaze to the ceramic body, let it stand for 9 hours, and then fire it according to the ceramic process to obtain a ceramic product with antibacterial properties.

[0148] 20×20 mm experimental samples were cut from the antibacterial ceramic products of the examples and comparative examples and the ordinary ceramic products (control group). 0.1 ml of bacterial solution was dripped onto the sample surface to form a bacterial liquid film. Plastic film was then covered on the sample surface and incubated at 35°C (27°C for Candida albicans) under light for 24 hours. The colony counts of the antibacterial samples and the control samples were then measured. The inhibition rates of Escherichia coli, Staphylococcus aureus, and Candida albicans were calculated according to the following formula: Inhibition rate = (control sample colony count - antibacterial sample colony count) / control sample colony count × 100%, where the control sample colony counts for Escherichia coli were 6×10 6cfu / ml, Staphylococcus 5×10 6 cfu / ml and Candida albicans 5×10 6 cfu / ml.

[0149] For the antibacterial ceramic products of the examples and comparative examples, a 6×6 grid pattern (1mm spacing, extending to the glaze layer) was cut on the film surface using a blade. Strong adhesive tape was applied and compacted, and then the film was rapidly peeled off at a 60° angle to calculate adhesion. The percentage of film peeled-off area was calculated as follows: Adhesion = (1 - number of peeled-off grid lines, 36) × 100%. Adhesion = (1 - number of peeled-off grid lines, 36) × 100%.

[0150] Table 1 shows the antibacterial rate of sample colonies

[0151] Escherichia coli (%) staphylococcus(%) Candida albicans (%) Example 1 98.7 98.0 99.1 Example 2 99.3 99.4 98.5 Example 3 98.6 98.5 99.2 Example 4 99.1 98.3 98.8 Comparative Example 1 83.5 83.7 83.6 Comparative Example 2 93.4 93.6 92.0 Comparative Example 3 95.2 94.9 94.7

[0152] Table 2 shows the adhesion of the samples

[0153] Shedding area ratio (%) Adhesion grade (0-5) Example 1 13 4 Example 2 11 4 Example 3 10 4 Example 4 13 4 Comparative Example 1 35 2 Comparative Example 2 15 3 Comparative Example 3 45 1

[0154] As can be seen from Tables 1 and 2, the ceramic products of the embodiments have higher antibacterial rates and adhesion to Escherichia coli, Staphylococcus aureus, and Candida albicans than the ceramic products of the comparative examples. This is because the fired ceramic is immersed in a chitosan-titanium dioxide composite sol. After calcination, the chitosan is carbonized to form a nitrogen-doped carbon layer that wraps the TiO2 nanoparticles. Nitrogen atoms replace the oxygen sites in the TiO2 lattice to form Ti-N bonds, and the band gap increases from 3.2eV to 2.8eV. The visible light absorption rate is increased to more than 2.3 times that of traditional TiO2 films. The carbon layer acts as an electron conductor, accelerating the extraction of photogenerated electrons and increasing the electron mobility by 10 times. Therefore, the response range is extended to the visible light region, and the sunlight utilization rate is increased to more than 30%, thereby improving the antibacterial ability under visible light.

[0155] Ag⁺ acts on the cell membrane / DNA, combines with -SH groups to inactivate respiratory enzymes, embeds into DNA to form pyrimidine dimers to block replication, and quickly kills. Cu²⁺ can cause mitochondria / reactive oxygen to burst, catalyze the Fenton reaction to produce reactive oxygen, destroy the electron transport chain, cause energy depletion, and carry out continuous killing. When Ag + :Cu 2+ When it is about 4:1, 4 times Ag + The concentration causes membrane proteins to denature rapidly, forming 2~5nm holes. 2+ Through the pores, it directly hits the target inside the cell. 2+ Supplement Ag + In order to address the shortcomings of anaerobic bacteria / fungi, the bimetallic system significantly improves the fungal killing rate. At the same time, the zirconium phosphate carrier matches the dual ion release rate.

[0156] Using zirconium phosphate as a carrier, the metal ion effect and chitosan-titanium dioxide composite film are synergistically combined in the photocatalytic effect. The functional effect of the prepared composite antibacterial and self-cleaning ceramic material is better than that of a single metal ion antibacterial material.

[0157] The carbonized chitosan product forms a chemical bond with the glaze layer, and the carboxyl group (-COOH) in the carbon layer reacts with the SiO2 in the glaze layer to prevent the TiO2 film from peeling off and improve the adhesion by more than 30%.

[0158] Comparative Example 1 is a pure TiO2 film. The unmodified TiO2 only responds to ultraviolet light, while the proportion of sunlight is less than 5%. The electron-hole recombination rate under visible light is greater than 90%, and the antibacterial rate decreases by 16%. It lacks the microbial adsorption effect of chitosan and the light response range expanded by nitrogen doping, so the antibacterial rate decreases by 16%; TiO2 and the glaze layer SiO2 are only bonded by van der Waals forces, and are easily peeled off under wet and hot stress. It lacks the Si-OC covalent bond generated by carbonization of chitosan, and the shedding area increases by 22%, the adhesion decreases, and the grade is reduced.

[0159] Comparative Example 2 is without antibacterial glaze layer and lacks Ag + :Cu 2+ The continuous ion antibacterial effect of TiO2 was not able to produce active oxygen, and the antibacterial rate decreased by 6%. The volume of uncarbonized chitosan swelled in water, causing the film layer to crack. Drying could not eliminate the hydrophilic groups, the shedding area increased by 2%, and the adhesion decreased slightly.

[0160] Comparative Example 3 is a non-photocatalytic film. The antibacterial glaze layer only kills bacteria by contact and cannot decompose microbial debris. After the surface biofilm accumulates, it blocks the release of Ag⁺ / Cu²⁺ and the antibacterial rate decreases by 4%; it does not contain chitosan carbonization products to form chemical bonds with the glaze layer, and the adhesion is greatly reduced.

Claims

1. A ceramic product with antibacterial properties, characterized in that: The ceramic product comprises a ceramic substrate, an antibacterial glaze layer applied on the surface of the substrate, and a chitosan-titanium dioxide composite sol film coated on the glaze layer. The preparation method of the ceramic product with antibacterial properties is as follows: Step 1: Apply the antibacterial glaze to the ceramic body, let it stand for 8-10 hours, and then fire it according to the ceramic process; Step 2: Immerse the fired ceramic into chitosan-titanium dioxide composite sol, pull it at a speed of 6-12 cm / min, dry it at 60-80°C for 10-20 minutes after immersion, repeat the immersion-drying 3-4 times, and calcine it at 350-400°C for 1-3 hours to obtain a ceramic product with antibacterial properties.

2. The antibacterial ceramic product according to claim 1, characterized in that: The antibacterial glaze layer is formed by compounding glaze material and zirconium phosphate-loaded silver-copper antibacterial powder in a mass ratio of (95-105):

3.

3. The antibacterial ceramic product according to claim 1, characterized in that: In the step (2), the film thickness is controlled to be 20-75 nm after repeated pulling and coating.

4. The antibacterial ceramic product according to claim 2, characterized in that: The preparation process of the zirconium phosphate-supported silver-copper antibacterial powder is as follows: (1) Add 2L of 0.5mol / L zirconium oxychloride aqueous solution to 1.2mol / L phosphoric acid solution to generate zirconium phosphate colloid, filter and wash until neutral, and then dry at 110-120℃; (2) Add (1-3) g Li2CO3 to 100 g zirconium phosphate colloid, calcine it at 900-1400 ° C to form a powder, and then reduce the calcination temperature to 900-1200 ° C to obtain a zirconium phosphate carrier; (3) Using zirconium phosphate as a carrier, silver ions and copper ions are loaded, wherein the molar ratio of silver ions to copper ions is 1: (2.9-3.1); (4) Calcine the metal ion-loaded zirconium phosphate at 450-460°C for 2-4 hours and grind it through a 280-290 mesh sieve.

5. The antibacterial ceramic product according to claim 1, characterized in that: The preparation method of the chitosan-titanium dioxide composite sol is: A chitosan acetic acid solution with a mass concentration of 1-5% is mixed with nano-TiO2 powder with a particle size of 10-50 nm, a cross-linking agent is added, and the mixture is mechanically stirred for 0.5-1 h and then ultrasonically treated for 1-2 h to obtain a liquid sol.

6. The antibacterial ceramic product according to claim 5, characterized in that: The cross-linking agent in the step is citric acid.

7. The antibacterial ceramic product according to claim 5, characterized in that: The mass ratio of the chitosan solution, the cross-linking agent and TiO2 in the step is 100:(1-5):(10-30).