Antibacterial UV curing alumite color layer coating and preparation method thereof

Abstract

The invention relates to the technical field of coatings, and particularly provides an antibacterial UV curing alumite color layer coating and a preparation method thereof.The coating comprises 30-40 parts of light-cured acrylic resin, 10-15 parts of halloysite nanotubes loaded with surfactin and the like. Halloysite nanotubes are etched by hydrochloric acid to expand a tube cavity, the surfactin loading efficiency is enhanced through polyethyleneimine modification, sudden release is reduced through silane end capping, and a carrier reaming-electrostatic adsorption-slow release end capping synergistic system is formed. After etching, the nanotube is dissolved in an alkaline environment to realize pH response release, and surfactin is antibacterial through a dual mechanism of destroying a bacterial membrane and generating active oxygen. The antibacterial rate of the coating on escherichia coli after being subjected to damp-heat aging for 500 hours is larger than 90%, the color difference delta E after QUV aging is smaller than 1.5, the adhesive force reaches 4B, and the coating has long-acting antibacterial property, intelligent release and high appearance stability and has good application prospects.

Description

Technical Field

[0001] The invention relates to the technical field of coatings, and in particular to an antibacterial UV-curing electrochemical aluminum color layer coating and a preparation method thereof. Background Art

[0002] Electrochemical aluminum color layer paint is widely used in different fields such as automotive interior, electronic products, home decoration, etc. These products are frequently touched by users. If the paint lacks antibacterial properties, the growth of microorganisms may lead to health risks and poor user experience.

[0003] Therefore, antibacterial active ingredients need to be added to the electroplated aluminum color layer coating to solve these problems. At present, traditional antibacterial agents have been used in coatings, such as natural antibacterial agents, organic antibacterial agents and inorganic antibacterial agents. However, these antibacterial agents all have defects and shortcomings in different aspects. For example, traditional natural antibacterial agents are easily degraded in a hot and humid environment, and inorganic nanoparticle antibacterial agents are prone to cause surface defects such as orange peel and keyholes.

[0004] Surfactin is a cyclic lipopeptide secreted by Bacillus. It inserts into the bacterial cell membrane through its affinity structure, destroys the integrity of the lipid bilayer, causes membrane perforation and leakage of cell contents. Under light or oxidation conditions, the phenolic hydroxyl groups on its surface can also be oxidized to quinone substances, which can produce ROS such as hydroxyl radicals through Fenton reaction or photocatalysis, which can destroy viral capsids or bacterial DNA. Although surfactin has excellent antibacterial properties, its molecular weight is small, and it is easy to agglomerate and form precipitation when added directly, resulting in poor coating uniformity. It is also easy to oxidize and degrade under light or humid and hot environments. The antibacterial rate drops seriously after 200 hours, and it will cause the coating to turn yellow. Summary of the invention

[0005] In view of this, the present invention proposes an antibacterial UV-curable electrochemical aluminum color layer coating which uses surfactant for antibacterial effect and has better antibacterial stability and durability, and a preparation method thereof.

[0006] The technical solution of the present invention is implemented as follows: The present invention provides an antibacterial UV-curing electrochemical aluminum color layer coating, the raw materials of which are calculated by weight and include: 30-40 parts of photocurable acrylic resin, 40-80 parts of solvent, 10-15 parts of halloysite nanotubes loaded with surfactant, 5-10 parts of filler, 3-5 parts of photoinitiator and 1-2 parts of leveling agent.

[0007] In the above embodiment, halloysite nanotubes are used as a porous structure to load the surfactant, which effectively avoids the aggregation and rapid release of the surfactant. The aluminosilicate surface of the halloysite nanotubes can be partially welded in the weakly alkaline environment caused by bacterial metabolism, achieving a certain degree of pH response to release the surfactant. This effectively solves the aggregation, stability and yellowing problems of the surfactant in the coating.

[0008] In some embodiments, the method for preparing surfactin-loaded halloysite nanotubes comprises the following steps:

[0009] S1. Etching the halloysite nanotubes with 0.1-0.2M dilute hydrochloric acid, stirring at 500-1000rpm for 2-4h, centrifugally washing until the pH is ≥6.5, adding 1-10% polyethyleneimine to the etched halloysite nanotubes in a phosphate buffer solution with a pH of 6.5-7.5, ultrasonically treating for 20-40min, and centrifugally drying to obtain the halloysite nanotubes with polyethyleneimine deposited on the surface;

[0010] S2. Surfactant is dissolved in an acetic acid-sodium acetate buffer solution with a pH of 4.5-5.5, and the mass volume ratio of surfactin to the acetic acid-sodium acetate buffer solution is 10:1;

[0011] S3. The obtained halloysite nanotubes with polyethyleneimine deposited on the surface and the surfactin solution are subjected to ultrasonic dispersion treatment in a phosphate buffer solution with a pH of 7-9 for 20-40 minutes, and then centrifuged and dried to obtain the halloysite nanotubes loaded with surfactin.

[0012] In the above-mentioned method, the natural hollow tubular structure of halloysite nanotubes can physically block ultraviolet rays and moisture, thereby protecting the surfactant loaded therein. Secondly, the use of polyethyleneimine modification can enhance the binding force between the surfactant and the halloysite nanotubes through electrostatic action.

[0013] In some embodiments, the amount of surfactin is 15-27% of the halloysite nanotubes.

[0014] In some embodiments, the halloysite nanotubes loaded with surfactant are end-capped, and the treatment method includes: dispersing the halloysite nanotubes loaded with surfactant in ethanol, adding 3-aminopropyltriethoxysilane, stirring and reacting at 55-65°C for 4-6 hours, centrifuging and washing until neutral, and vacuum drying to obtain end-capped halloysite nanotubes loaded with surfactant, and the amount of 3-aminopropyltriethoxysilane used is 0.5-2% of the halloysite nanotubes loaded with surfactant.

[0015] Using 3-aminopropyltriethoxysilane to seal the tube mouth can reduce the sudden release of surfactant and enhance the interfacial bonding force with the resin collective through siloxane bonds.

[0016] In some embodiments, the photocurable acrylic resin is at least one of epoxy acrylate and polyurethane acrylate.

[0017] In some embodiments, the filler is nano-silica.

[0018] In some embodiments, the solvent is deionized water.

[0019] In some embodiments, the photoinitiator is at least one of Irgacure 651 and TPO.

[0020] In some embodiments, the leveling agent is a mixture of BYK 333 and Tego Glide 410.

[0021] In a second aspect, the present invention also provides a method for preparing an antibacterial UV-curing electrochemical aluminum color layer coating, comprising: mixing and stirring the raw materials in a proportion to obtain an antibacterial UV-curing electrochemical aluminum color layer coating.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The present invention adopts the scheme of halloysite nanotube loading and silane termination, which preliminarily solves the problems of aggregation and degradation of surfactant, and effectively improves its antibacterial properties in the coating and the problem of poor appearance stability. DETAILED DESCRIPTION

[0024] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] Unless otherwise specified, the methods used in the following examples are all conventional methods. Unless otherwise specified, the materials, reagents and instruments used are all conventional materials, reagents and instruments in the art, and can be obtained by those skilled in the art through commercial channels.

[0026] When an amount, concentration or other value or parameter is expressed as a range, a preferred range or a range defined by a series of upper preferred values ​​and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value, regardless of whether the range is disclosed separately. For example, when a range of "1 to 5" is disclosed, the described range should be interpreted as including the range "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described herein, unless otherwise stated, the range is intended to include its end values ​​and all integers and fractions within the range. In the present specification and claims, range definitions can be combined and / or interchanged, and if not otherwise stated, these ranges include all subranges contained therein.

[0027] Example 1

[0028] This embodiment provides a technical solution using halloysite nanotubes loaded with surfactant

[0029] The raw material ratio is as follows:

[0030] Photocurable resin: epoxy acrylate 35g, deionized water 60g, surfactant-loaded halloysite nanotubes 12g, nano-SiO2 7g, Irgacure651 4g, BYK333 and Tego Glide 410 1.5g in a mass ratio of 1:1.

[0031] The preparation method of the halloysite nanotubes loaded with surfactant is as follows:

[0032] S1. Etching halloysite nanotubes (average outer diameter 50 nm, average inner diameter 20 nm, tube length 1 μm) with 0.15 M dilute hydrochloric acid, stirring at 800 rpm for 2 h, centrifuging and washing until pH ≥ 6.5, adding 5% polyethyleneimine to the etched halloysite nanotubes in a phosphate buffer solution (PBS) with a pH of 7, ultrasonically treating at 400 W for 30 min, and centrifuging and drying to obtain halloysite nanotubes with polyethyleneimine deposited on the surface;

[0033] S2, surfactin was dissolved in an acetic acid-sodium acetate buffer solution with a pH of 5.0, and the mass volume ratio of surfactin to the acetic acid-sodium acetate buffer solution was 10:1;

[0034] S3. Ultrasonic dispersion treatment of the obtained halloysite nanotubes with polyethyleneimine deposited on the surface and the surfactin solution in a phosphate buffer solution with a pH of 8 for 20-40 min, followed by centrifugation and drying to obtain surfactin-loaded halloysite nanotubes, wherein the amount of surfactin used is 15 wt% of the halloysite nanotubes.

[0035] Coating preparation:

[0036] The raw materials are mixed and stirred evenly according to a proportion to obtain an antibacterial UV-curing electrochemical aluminum color layer coating.

[0037] Example 2

[0038] In this embodiment, based on the embodiment 1, the halloysite nanotubes loaded with surfactant are further end-capped.

[0039] The preparation method of the surfactant-loaded halloysite nanotubes also includes:

[0040] S4. Disperse the surfactant-loaded halloysite nanotubes in ethanol, add 3-aminopropyltriethoxysilane, stir and react at 60°C for 4 hours, wash by centrifugation until neutral, and dry in vacuo to obtain end-capped halloysite nanotubes loaded with surfactant, wherein the amount of 3-aminopropyltriethoxysilane used is 1.5% of the surfactant-loaded halloysite nanotubes.

[0041] Example 3

[0042] This embodiment is based on the embodiment 2, and the hydrochloric acid etching process is changed

[0043] The preparation method of the surfactant-loaded halloysite nanotubes is different in that:

[0044] S1. Etch the halloysite nanotubes with 0.15M dilute hydrochloric acid and stir at 800rpm for 4h. At the same time, increase the amount of surfactant to 27wt% of the halloysite nanotubes.

[0045] Comparative Example 1

[0046] The difference between this comparative example and Example 1 is that surfactin is used to replace the halloysite nanotubes loaded with surfactin, and the amount of surfactin used is 1.8 g (equivalent to 15 wt % loaded in Example 1).

[0047] Comparative Example 2

[0048] The difference between this comparative example and Example 1 is that the halloysite nanotubes in Example 1 are replaced by an equal mass of mesoporous SiO2 (average particle size 100 nm).

[0049] Comparative Example 3

[0050] The difference between this comparative example and Example 1 is that the halloysite nanotubes are not subjected to etching treatment.

[0051] The preparation method of the surfactant-loaded halloysite nanotubes is different in that:

[0052] S1. Add 5% polyethyleneimine to the halloysite nanotubes in a phosphate buffer solution with a pH of 7, perform ultrasonic treatment at 400W for 30 minutes, and centrifuge and dry to obtain the halloysite nanotubes with polyethyleneimine deposited on the surface.

[0053] Comparative Example 4

[0054] The difference between this comparative example and Example 1 is that the halloysite nanotubes are not treated with polyethyleneimine deposition.

[0055] The preparation method of the halloysite nanotubes loaded with surfactant is different in that:

[0056] S1. Etching the halloysite nanotubes with 0.15M dilute hydrochloric acid, stirring at 800 rpm for 2 h, washing by centrifugation until the pH value is ≥ 6.5, and then centrifuging and drying to obtain the halloysite nanotubes.

[0057] The antibacterial UV-curing electroplated aluminum color layer coating prepared above was evenly coated on the surface of the electroplated aluminum substrate, and cut into 5cm*5cm samples after UV light curing, and then the antibacterial persistence test, yellowing inhibition effect and pH response release effect test were carried out respectively.

[0058] Escherichia coli (ATCC 25922) and Staphylococcus aureus (ATCC 6538) were selected and inoculated into LB liquid medium. They were cultured at 37°C until the logarithmic growth phase (OD600≈0.5). 100 μL of bacterial solution (concentration 1×10 6 CFU / mL) was evenly coated on the surface of the sample, covered with a sterile polyethylene film, incubated at 37°C and 90% RH for 24 hours, eluted with PBS buffer, and coated on an agar plate after gradient dilution. The coated sample was placed in a constant temperature and humidity chamber (85°C, 85% RH), and samples were taken regularly (0h, 200h, 500h). The antibacterial rate of the aged sample was tested according to the ISO 22196 method. The surfactin content was quantitatively analyzed by HPLC (C18 chromatographic column, mobile phase acetonitrile / water = 70 / 30, detection wavelength 214nm), and the half-life was calculated to obtain the data shown in the following table:

[0059]

[0060] According to the comparison of the above embodiments and comparative data, it can be seen that the end-capping treatment increases the 500-hour antibacterial rate from 62.3% to 85.4%, and the half-life is extended by 1 times, proving that silane end-capping effectively reduces sudden release; the HNTs carrier (91.2%) is significantly better than mesoporous SiO2 (50.6%), highlighting the advantages of high loading capacity (27% vs 15%) and pH-responsive release; the antibacterial rate of unetched HNTs drops to 48.7%, proving the key role of the etching process in increasing the loading capacity.

[0061] Yellowing index test:

[0062] Use a colorimeter (D65 light source, 10° observation angle) to measure the initial chromaticity value (L*, a*, b*) of the coating.

[0063] QUV aging: The sample was placed in a QUV accelerated aging box (UVA-340 lamp, 0.76W / m 2 , 60°C), and continuously irradiated for 200 hours.

[0064] Grouping Initial ΔE value ΔE value after QUV aging Gloss (60°GU) Example 1 1.2 2.8 92 Example 2 1.3 2.1 95 Example 3 1.1 1.4 97 Comparative Example 1 1.5 7.9 80 Comparative Example 2 1.3 3.5 90 Comparative Example 3 1.4 4.1 88 Comparative Example 4 1.6 5.2 85

[0065] From the comparison of the above data, it can be seen that HNTs loading + end-capping treatment reduces ΔE from 7.9 to 1.4, and the glossiness remains at 97GU, proving that carrier protection effectively inhibits the oxidation of surfactant; end-capping treatment reduces ΔE from 4.1 to 2.1, and silane cross-linking reduces coating microcracks.

[0066] Release kinetics test (pH responsiveness)

[0067] HNTs loaded with surfactin (10 mg) were dispersed in 10 mL PBS buffer (pH 7.0 and pH 8.0), and oscillated at 37°C (100 rpm). 1 mL of the solution was taken at 0 h, 6 h, 12 h, and 24 h, and the supernatant was taken after centrifugation to determine the surfactin concentration and calculate the cumulative release rate.

[0068] Grouping pH 7.0 response release (24h) pH 8.0 response release (24h) Release rate increased multiples Example 3 18％ 65％ 3.6× Example 1 35％ 40％ 1.1× Comparative Example 3 25％ 35％ 1.4×

[0069] The release rate of Example 3 in an alkaline environment (pH 8.0) is 1.86 times that of Example 3, proving that the etching process gives HNTs pH responsiveness; the initial release rate of Example 1 (uncapped) is relatively high (35%), and after capping (Example 2), the initial release rate drops to 12%.

[0070] Example 3 achieves a 500-hour antibacterial rate of >90% through etching optimization + high load + end-capping treatment, far exceeding Comparative Example 2 (50.6%) and Comparative Example 3 (48.7%).

[0071] The above description is only a preferred embodiment 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 protection scope of the present invention.

Claims

1. An antibacterial UV-curing electrochemical aluminum color coating, characterized in that: The raw materials thereof are calculated by weight and include: 30-40 parts of photocurable acrylic resin, 40-80 parts of solvent, 10-15 parts of halloysite nanotubes loaded with surfactant, 5-10 parts of filler, 3-5 parts of photoinitiator and 1-2 parts of leveling agent.

2. The antibacterial UV curing electrochemical aluminum color coating according to claim 1, characterized in that: The preparation method of the surfactin-loaded halloysite nanotubes comprises the following steps: S1. Etching the halloysite nanotubes with 0.1-0.2M dilute hydrochloric acid, stirring at 500-1000rpm for 2-4h, centrifugally washing until the pH is ≥6.5, adding 1-10% polyethyleneimine to the etched halloysite nanotubes in a phosphate buffer solution with a pH of 6.5-7.5, ultrasonically treating for 20-40min, and centrifugally drying to obtain the halloysite nanotubes with polyethyleneimine deposited on the surface; S2. Surfactant is dissolved in an acetic acid-sodium acetate buffer solution with a pH of 4.5-5.5, and the mass volume ratio of surfactin to the acetic acid-sodium acetate buffer solution is 10:1; S3. The obtained halloysite nanotubes with polyethyleneimine deposited on the surface and the surfactin solution are subjected to ultrasonic dispersion treatment in a phosphate buffer solution with a pH of 7-9 for 20-40 minutes, and then centrifuged and dried to obtain the halloysite nanotubes loaded with surfactin.

3. The antibacterial UV curing electrochemical aluminum color coating according to claim 2, characterized in that: The dosage of the surfactin is 15-27% of the halloysite nanotubes.

4. The antibacterial UV curing electrochemical aluminum color coating according to claim 1, characterized in that: The halloysite nanotubes loaded with surfactant are subjected to end-capping treatment, and the treatment method comprises: dispersing the halloysite nanotubes loaded with surfactant in ethanol, adding 3-aminopropyltriethoxysilane, stirring and reacting at 55-65° C. for 4-6 hours, washing by centrifugation until neutral, and vacuum drying to obtain the halloysite nanotubes loaded with surfactant, wherein the amount of 3-aminopropyltriethoxysilane used is 0.5-2% of the halloysite nanotubes loaded with surfactant.

5. The antibacterial UV curing electrochemical aluminum color coating according to claim 1, characterized in that: The photocurable acrylic resin is at least one of epoxy acrylate and polyurethane acrylate.

6. The antibacterial UV curing electrochemical aluminum color coating according to claim 1, characterized in that: The filler is nano silicon dioxide.

7. The antibacterial UV curing electrochemical aluminum color coating according to claim 1, characterized in that: The solvent is deionized water.

8. The antibacterial UV curing electrochemical aluminum color coating according to claim 1, characterized in that: The photoinitiator is at least one of Irgacure 651 and TPO.

9. The antibacterial UV curing electrochemical aluminum color coating according to claim 1, characterized in that: The leveling agent is a mixture of BYK333 and Tego Glide 410.

10. A method for preparing an antibacterial UV-curable electrochemical aluminum color coating, characterized in that: include: The raw materials are mixed and stirred evenly according to a proportion to obtain an antibacterial UV-curing electrochemical aluminum color layer coating.

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