Efficient antibacterial coating based on hexagonal boron nitride and preparation process of efficient antibacterial coating

Abstract

The invention discloses an efficient antibacterial coating based on hexagonal boron nitride and a preparation process of the efficient antibacterial coating, and belongs to the field of antibacterial coatings. The coating is prepared by uniformly mixing h-BN micron particles with the particle size of 2-10 microns and h-BN nano particles with the particle size of 20-500 nm serving as core antibacterial components with auxiliary materials such as an adhesive, deionized water, a suspending agent, a dispersing agent and a defoaming agent. By innovatively adopting a nanoscale h-BN material, the product realizes the following technical breakthroughs: the antibacterial efficiency is remarkably improved; the environment-friendly characteristic is realized; the environmental stability is excellent; and the application adaptability is wide. Compared with the traditional silver-based, copper-based and other metal ion type antibacterial coatings, the product avoids the risk of metal ion migration, solves the technical bottlenecks of poor temperature resistance of an organic antibacterial coating and strong light dependence of a photocatalytic coating, and has important industrial application value in the fields of medical equipment, building decoration and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of novel environmentally friendly antibacterial coatings, and relates to a high-efficiency antibacterial coating based on hexagonal boron nitride (h-BN) and a preparation process thereof. Background Art

[0002] In daily life, bacterial contamination has become a health hazard that cannot be ignored. From hospital diagnostic equipment to conveyor belts in food processing plants, from children's toys to public transportation handrails, the growth of bacteria not only accelerates the aging of materials but also becomes an invisible medium for the spread of disease. Traditional disinfection methods have defects such as short effectiveness and residual toxicity. The emergence of antimicrobial coatings provides a solution - by constructing a long-lasting antimicrobial barrier on the surface of objects, it can not only inhibit the reproduction of microorganisms but also avoid damage to the substrate caused by repeated disinfection. This innovative idea of ​​"solidifying" the protective function on the surface of the material has far-reaching significance for improving medical safety, ensuring food safety, and improving public environmental hygiene.

[0003] Current antimicrobial coatings are primarily categorized as metal ion-based, photocatalytic, and organic. While metal ion coatings (such as those in Chinese Patent Publication No. CN112980255A) exhibit broad-spectrum antimicrobial properties, silver ions are difficult to degrade in the environment, leading the EU to classify them as persistent pollutants and restrict their use. Organic antimicrobial agents such as quaternary ammonium salts are prone to volatilization and ineffectiveness (such as those in Chinese Patent Publication No. CN113061378A), and their antimicrobial effectiveness decreases in high-temperature and high-humidity environments. Photocatalytic antimicrobial coatings are highly dependent on light (such as those in Chinese Patent Publication No. CN111203218A), with their antimicrobial effectiveness significantly decreasing in low-light or no-light conditions. Therefore, there is an urgent need to develop environmentally friendly and universally compatible antimicrobial coatings. Summary of the Invention

[0004] The present invention provides a high-efficiency antibacterial coating product and preparation process based on hexagonal boron nitride (h-BN). h-BN powder is selected as the main raw material, and adhesives, dispersants, suspending agents and defoaming agents are added to prepare the h-BN coating with excellent coating performance and extremely strong antibacterial properties.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] A high-efficiency antibacterial coating based on hexagonal boron nitride is composed of the following raw materials in the following mass percentages:

[0007] h-BN powder, mass percentage is 15%~50%;

[0008] Adhesive, mass percentage is 5%~25%;

[0009] Suspension agent, mass percentage is 0.2%~2%;

[0010] Dispersant, mass percentage is 0.2%~2%;

[0011] Defoaming agent, mass percentage is 0.1%~1%;

[0012] Deionized water, mass percentage is 40%~70%.

[0013] Preferably, the purity of the h-BN powder is ≥80%.

[0014] Preferably, the h-BN powder is a mixture of particles with a particle size of 2 to 10 μm and particles with a particle size of 20 nm to 500 nm.

[0015] More preferably, the h-BN powder has a particle size of 2-10 μm accounting for 50-100%, and a particle size of 20-500 nm accounting for 0-50%.

[0016] Preferably, the h-BN powder with a particle size of 2-10 μm has a flake-like micromorphology, and the h-BN powder with a particle size of 20-500 nm has one or both of flake and spherical micromorphologies. Compared to micron-sized h-BN, nano-sized h-BN has a higher specific surface area and greater activity. The sharper edges of flake-shaped h-BN effectively destroy microbial structures, enhancing the antibacterial properties of h-BN coatings.

[0017] Preferably, the adhesive is one of a water-based silicone resin and a water-based silicone-modified resin. For example, the water-based silicone resin may be silicone resin or methylphenyl silicone resin emulsion; the water-based silicone-modified resin may be a water-based silicone-modified acrylic resin, a water-based silicone-modified alkyd resin, a polyurethane-modified silicone resin, a water-based acrylic-modified silicone high-temperature resistant paint, a silicone-modified epoxy resin, or a silicone-modified alkyd resin.

[0018] Preferably, the suspending agent is one or more of organically modified hectorite and carboxymethyl cellulose. The organically modified hectorite can be modified by using cetyltrimethylammonium bromide (CTAB), coupling agent γ-aminopropyltriethoxysilane (KH550) or polyacrylamide.

[0019] The modification process uses cetyltrimethylammonium bromide (CTAB): a cetyltrimethylammonium bromide (CTAB) solution (CTAB is dissolved in an ethanol / water mixed solvent with an ethanol / water volume ratio of 9:1 to prepare a 0.5-3 mol / L solution. The solution is stirred at room temperature in a weakly acidic environment at pH 4-5 for 30 minutes to fully dissociate the CTAB into cationic active groups) is mixed with a hectorite suspension (hectorite is dissolved in ultrapure water, impurity ions are removed by dialysis, and the suspension is stirred at high speed in 65°C water to form a uniform suspension. The suspension is cooled and allowed to stand for 10 days). The mass ratio of CTAB to hectorite is 1:20 (dry basis). The reaction system maintains a pH of 7-8 and is blocked at 65°C for 24 hours. The cationic groups of CTAB exchange with the cations between the hectorite layers, making the surface hydrophobic.

[0020] ‌Modification process using silane coupling agent‌:

[0021] KH-550 was dissolved in an ethanol / water mixed solvent with an ethanol / water volume ratio of 9:1, the pH was adjusted to 4-5, and hydrolysis was stirred at room temperature for 30 minutes to generate a silanol derivative; the derivative was then added dropwise to a hectorite suspension (hectorite was dissolved in ultrapure water, impurity ions were removed by dialysis, and a uniform suspension was formed by high-speed stirring in 65°C water. After cooling, the suspension was allowed to stand for 10 days). The mass ratio of KH-550 to hectorite was 1:20 (dry basis). The reaction system maintained a pH of 7-8, the temperature was controlled at 60°C, and stirring was continued at 200 rpm for 12 hours. The derivative was combined with the hydroxyl groups on the surface of the hectorite through siloxane bonds to form an organic-inorganic interface layer, thereby enhancing compatibility with the polymer.

[0022] Polyacrylamide modification of hectorite:

[0023] A hectorite suspension (hectorite is dissolved in ultrapure water, impurity ions are removed by dialysis, and then stirred at high speed in 65°C water to form a uniform suspension. After cooling, the suspension is allowed to stand for 10 days) is slowly added to the PAM solution. The mass ratio of PAM to hectorite is typically 1:8, and the molecular weight of PAM is controlled between 12 and 18 million. The temperature is maintained at 60°C and stirred at 200 rpm for 24 hours. The PAM molecular chains are adsorbed on the surface and between the layers of the hectorite through electrostatic interactions or hydrogen bonds, forming an "organic-inorganic" composite structure. The solid-liquid separation is carried out, and the solution is pre-frozen at -30°C and then vacuum-dried to retain the porous structure. The solution is sintered at 500°C for 2 hours to enhance thermal stability and remove residual organic matter.

[0024] Preferably, the dispersant is one of polyvinyl pyrrolidone and polyethylene oxide.

[0025] Preferably, the defoamer is a non-silicone polymer defoamer and a polyether-modified silicon defoamer. The non-silicone polymer defoamer can be a polyether defoamer, a surfactant defoamer such as a nonionic surfactant (fatty alcohol polyoxyethylene ether), or a polyurethane defoamer.

[0026] A preparation process of a high-efficiency antibacterial coating based on hexagonal boron nitride comprises the following steps:

[0027] 1) Dry mixing: Weigh h-BN powders of 2-10 μm and 20-500 nm in proportion and dry mix for 5 min to ensure uniform particle size distribution.

[0028] 2) Solution preparation: Premix the weighed deionized water, adhesive, dispersant, and defoamer for 1-3 minutes to form a homogeneous solution;

[0029] 3) Stirring: Add the dry-mixed h-BN powder to the solution prepared in step 2) in small amounts and stir for 15 minutes.

[0030] 4) Adding suspending agent: After h-BN powder is dispersed, suspending agent is added to activate it at high speed to form a thixotropic network, thus obtaining an antibacterial coating.

[0031] Preferably, the high-speed activation condition in step 4) is a rotation speed ≥ 2000 rpm for 10 to 15 min.

[0032] Preferably, the antibacterial coating prepared by the preparation process is applied to the substrate surface by brushing or spraying, the coated sample is dried in a dry and cool place for 12 hours, and the dried sample is placed at 110° C. and dried for 12 hours.

[0033] Preferably, the substrate relates to fields such as diagnostic equipment, toys, public transportation, and food processing plant conveying mechanisms.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1) Significantly improved antibacterial efficacy: Nano-h-BN has a larger specific surface area and surface energy, and exhibits higher antibacterial activity against pre-formed biofilms. In addition, the flaky nano-h-BN has sharp edges that can effectively destroy bacterial structures.

[0036] 2) Environmentally friendly features: The materials used are completely free of heavy metals and other harmful substances, in line with the concept of green chemistry.

[0037] 3) Excellent environmental stability: It can maintain stable antibacterial properties under high temperature and no light conditions.

[0038] 4) Excellent storage stability: By adding polyacrylamide organically modified hectorite or carboxymethyl cellulose, the suspension performance of h-BN coating is significantly improved, effectively inhibiting the occurrence of sedimentation, thereby giving the coating excellent storage stability.

[0039] 5) Good application performance: The addition of polyvinyl pyrrolidone or polyethylene oxide significantly improves the rheological properties of h-BN coatings. These dispersants effectively reduce the viscosity of h-BN coatings and adjust the surface tension, making them easier to spread evenly during application, thereby improving leveling and film surface quality. Furthermore, they enhance the coating's applicability, ensuring a uniform and dense coating structure on a variety of substrates. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 Graphs showing the antibacterial test results for comparative examples and embodiments. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments and drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0042] The purity of the h-BN powder used in the following examples is ≥95%, and the adhesive, suspending agent, dispersant, and defoaming agent used are common chemical substances widely used in chemical research and industry. Example 1

[0043] The high-efficiency antibacterial coating based on hexagonal boron nitride (h-BN) of this embodiment is prepared from the following raw materials in the following mass percentages:

[0044] h-BN powders (mass ratio 7:3) with a particle size of 2 to 10 μm and a particle size of 20 to 500 nm, respectively, account for 30% by mass.

[0045] The adhesive is methylphenyl silicone resin (‌IOTA 6156C), with a mass percentage of 15%;

[0046] The suspending agent is polyacrylamide-modified hectorite, with a mass percentage of 0.5%;

[0047] The dispersant is polyvinyl pyrrolidone, with a mass percentage of 0.3%;

[0048] The defoamer is a polyether modified silicone defoamer (HR-3062E), with a mass percentage of 0.2%;

[0049] Deionized water, mass percentage is 54%.

[0050] The preparation process of the high-efficiency antibacterial coating based on hexagonal boron nitride (h-BN) in this embodiment includes the following steps:

[0051] 1) Dry mixing: Weigh h-BN powders of 2-10 μm and 20-500 nm in proportion and dry mix for 5 min to ensure uniform particle size distribution.

[0052] 2) Solution preparation: Premix the weighed deionized water, adhesive, dispersant, and defoamer in a blender for 3 minutes to form a homogeneous solution;

[0053] 3) Stirring: Add the dry-mixed h-BN powder to the solution prepared in step 2) in small amounts several times and stir and disperse in a blender for 15 minutes;

[0054] 4) Adding suspending agent: After h-BN powder is dispersed, add suspending agent and activate at high speed (≥2000 rpm, 15 min) to form a thixotropic network;

[0055] 5) Coating: Apply the prepared coating to the substrate surface by brushing or spraying;

[0056] 6) Shade drying: Shade dry the coated sample in a dry and cool place for 12 hours;

[0057] 7) Drying: Dry the shade-dried sample at 110°C for 12 h.

[0058] The properties of the prepared high-efficiency antibacterial coating based on hexagonal boron nitride (h-BN) are shown in Tables 1 and Figure 1 . Example 2

[0059] The high-efficiency antibacterial coating based on hexagonal boron nitride (h-BN) in this embodiment is prepared from the following raw materials in the following mass percentages:

[0060] h-BN powder with a flake shape and a particle size of 2 to 10 μm, with a mass percentage of 30%;

[0061] The adhesive is methylphenyl silicone resin (‌IOTA 6156C), with a mass percentage of 15%;

[0062] The suspending agent is polyacrylamide-modified hectorite, with a mass percentage of 0.5%;

[0063] The dispersant is polyvinyl pyrrolidone, with a mass percentage of 0.3%;

[0064] The defoamer is a polyether modified silicone defoamer (HR-3062E), with a mass percentage of 0.2%;

[0065] Deionized water, mass percentage is 54%.

[0066] The process steps are the same as in Example 1.

[0067] The properties of the prepared high-efficiency antibacterial coating based on hexagonal boron nitride (h-BN) are shown in Tables 1 and Figure 1 . Example 3

[0068] The high-efficiency antibacterial coating based on hexagonal boron nitride (h-BN) in this embodiment is prepared from the following raw materials in the following mass percentages:

[0069] h-BN powders of flaky particles with a particle size of 2 to 10 μm and flaky particles with a particle size of 20 to 500 nm (mass ratio of 7:3) with a mass percentage of 25%;

[0070] The adhesive is water-based silicone-modified acrylic resin (S-611), with a mass percentage of 15%;

[0071] The suspending agent is carboxymethyl cellulose, with a mass percentage of 0.5%;

[0072] The dispersant is polyethylene oxide, with a mass percentage of 0.3%;

[0073] The defoamer is a non-silicone polymer defoamer (BYK-1640), with a mass percentage of 0.2%;

[0074] Deionized water, mass percentage is 59%.

[0075] The process steps are the same as in Example 1.

[0076] The properties of the prepared high-efficiency antibacterial coating based on hexagonal boron nitride (h-BN) are shown in Tables 1 and Figure 1 . Example 4

[0077] The high-efficiency antibacterial coating based on hexagonal boron nitride (h-BN) in this embodiment is prepared from the following raw materials in the following mass percentages:

[0078] h-BN powder with a flake shape and a particle size of 2 to 10 μm, with a mass percentage of 25%;

[0079] The adhesive is water-based silicone-modified acrylic resin (S-611), with a mass percentage of 15%;

[0080] The suspending agent is carboxymethyl cellulose, with a mass percentage of 0.5%;

[0081] The dispersant is polyethylene oxide, with a mass percentage of 0.3%;

[0082] The defoamer is a non-silicone polymer defoamer (BYK-1640), with a mass percentage of 0.2%;

[0083] Deionized water, mass percentage is 59%.

[0084] The process steps are the same as in Example 1.

[0085] The properties of the prepared high-efficiency antibacterial coating based on hexagonal boron nitride (h-BN) are shown in Tables 1 and Figure 1 .

[0086] Antibacterial test method: co-culture + plate spread count test

[0087] Use a graduated cylinder to measure 100 mL of distilled water and pour it into a 250 mL reagent bottle. Use an analytical electronic balance to weigh 3.5 g of potato dextrose broth (PDB liquid medium, 5 g / L potato extract powder, 15 g / L glucose, 10 g / L peptone, 5 g / L sodium chloride), add it and mix well. Sterilize it in a high-temperature and high-pressure steam autoclave at 121°C for 20 min. After cooling to room temperature, place it in a refrigerator at 4°C for later use.

[0088] Use a graduated cylinder to measure 100 mL of distilled water into a 250 mL reagent bottle. Using an analytical electronic balance, weigh 4.6 g of potato dextrose agar medium (200 g peeled potatoes, 20 g glucose, 20 g agar, 1000 mL distilled water). Add the mixture and mix thoroughly. Sterilize in an autoclave at 115°C for 20 minutes. Once the medium cools to approximately 40-50°C, use an electric pipette to transfer 20 mL of the medium into a disposable sterile dish.

[0089] Take two 12 mL bacterial culture tubes and add 3 mL of PDB liquid medium to each. Pick a single colony from the Candida albicans solid culture medium and add it to the liquid medium. The other tube serves as a blank control. Incubate the tubes in a constant temperature shaker (28°C, 200 rpm) for 24 h.

[0090] Cut the samples into groups and place them in glass dishes. Sterilize them in a high-temperature, high-pressure steam autoclave at 121°C for 20 minutes and set aside. Dilute the bacterial solution to 105 CFU / mL with 1 / 500 PDB. Transfer the samples from the glass dishes to disposable Petri dishes and evenly drip 50 μL of the bacterial solution onto the surface of each sample. A control group, without sample, was placed in a 28°C incubator and incubated for 24 hours.

[0091] After incubation, elute the co-culture medium with 5 mL of sterile PBS and serially dilute the culture 10-fold with sterile PBS. Spread 100 μL of the dilution evenly on LB solid medium (10 g / L tryptone, 5 g / L yeast extract, 10 g / L sodium chloride, 15 g / L agar). Incubate in a 28°C incubator for 48 h. Remove the culture, photograph it, and record the number of colonies.

[0092] Note: The counting principle is based on the national standard GB4789.2-2016. Colony counts are performed when the colony count is between 30 CFU and 300 CFU. If no colonies grow at the minimum dilution factor, the sample demonstrates significant antibacterial efficacy.

[0093] The calculation method for bacterial solution concentration (CFU / mL) is: number of colonies × dilution factor × 10 (0.1 mL coating) × 100 (5 mL sterile PBS solution eluted with 50 μL bacterial solution)

[0094] Antibacterial rate = (1-concentration of bacterial solution in experimental group / concentration of bacterial solution in control group) × 100%

[0095] Viscosity test method: Use a rotational viscometer (specific model FA-NXS-11A) to test

[0096] Table 1 Properties of the high-efficiency antibacterial coatings prepared in Examples

[0097]

[0098] According to Table 1 and Figure 1 The results show that the antibacterial coatings prepared in Example 1 and Example 3 in Examples 1-4 of the present invention have more excellent antibacterial rates, and the antibacterial rates can still be maintained under no light conditions, indicating that the addition of nano-scale h-BN powder can further improve the antibacterial rate of the antibacterial coating.

[0099] The above description is only for illustration of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A high-efficiency antibacterial coating based on hexagonal boron nitride, characterized in that: The antibacterial coating is composed of the following raw materials in percentage by mass: h-BN powder, mass percentage is 15%~50%; Adhesive, mass percentage is 5%~25%; Suspending agent, mass percentage is 0.2%~2%; Dispersant, mass percentage is 0.2%~2%; Defoaming agent, mass percentage is 0.1%~1%; Deionized water, mass percentage is 40%~70%.

2. The high-efficiency antibacterial coating based on hexagonal boron nitride according to claim 1, characterized in that: The h-BN powder is a mixture of particles with a particle size of 2-10 μm and particles with a particle size of 20 nm-500 nm, wherein the particles with a particle size of 2-10 μm account for 50-100% and the particles with a particle size of 20-500 nm account for 0-50%.

3. The high-efficiency antibacterial coating based on hexagonal boron nitride according to claim 2, characterized in that: The microscopic morphology of the h-BN powder with a particle size of 2 to 10 μm is flake-shaped, and the microscopic morphology of the h-BN powder with a particle size of 20 to 500 nm is one or both of flake-shaped and spherical.

4. The high-efficiency antibacterial coating based on hexagonal boron nitride according to claim 1, characterized in that: The adhesive is one of a water-based organic silicone resin and a water-based organic silicone modified resin.

5. The high-efficiency antibacterial coating based on hexagonal boron nitride according to claim 1, characterized in that: The suspending agent is one or more of organic modified hectorite and carboxymethyl cellulose.

6. The high-efficiency antibacterial coating based on hexagonal boron nitride according to claim 1, characterized in that: The dispersant is one of polyvinyl pyrrolidone and polyethylene oxide.

7. The high-efficiency antibacterial coating based on hexagonal boron nitride according to claim 1, characterized in that: The defoamer is one of a non-silicon polymer defoamer and a polyether modified silicon defoamer.

8. A preparation process for a high-efficiency antibacterial coating based on hexagonal boron nitride, characterized in that: The preparation process comprises the following steps: 1) Dry mixing: Weigh h-BN powders of 2-10 μm and 20-500 nm in proportion and dry mix for 5 min to ensure uniform particle size distribution. 2) Solution preparation: Premix the weighed deionized water, adhesive, dispersant, and defoamer for 1-3 minutes to form a homogeneous solution; 3) Stirring: Add the dry-mixed h-BN powder to the solution prepared in step 2) in small amounts and stir for 15 minutes. 4) Adding suspending agent: After h-BN powder is dispersed, suspending agent is added to activate at high speed to form a thixotropic network, thus obtaining antibacterial coating.

9. The preparation process of the high-efficiency antibacterial coating based on hexagonal boron nitride according to claim 8, characterized in that: The conditions for high-speed activation in step 4) are a rotation speed ≥ 2000 rpm for 10 to 15 minutes.

10. The preparation process of the high-efficiency antibacterial coating based on hexagonal boron nitride according to claim 8, characterized in that: The antibacterial coating prepared by the preparation process is applied to the substrate surface by brushing or spraying, and the coated sample is dried in a dry and cool place for 12 hours, and the dried sample is placed at 110° C. and dried for 12 hours.

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