Preparation scheme and use method of a long-lasting mildew-proof multifunctional coating

Abstract

The present invention discloses a preparation method and use method of a long-acting mildew-proof multifunctional coating, wherein melamine, urea, formaldehyde and deionized water are first mixed in proportion to prepare a MUF prepolymer, and then mixed with cinnamon essential oil, 10wt% styrene-maleic anhydride copolymer solution and deionized water to prepare a long-acting mildew-proof microcapsule suspension, and finally the long-acting mildew-proof microcapsule suspension, PDMS modified solution and multi-walled carbon nanotubes are mixed to prepare a long-acting mildew-proof multifunctional coating. During use, the long-acting mildew-proof multifunctional coating is repeatedly sprayed 5 times on the surface of a wood block, dried at 80 ° C for 1 hour, and a long-acting mildew-proof multifunctional coating is formed after removing the solvent. The present invention utilizes microencapsulated plant essential oils and multi-walled carbon nanotubes to collaboratively construct a micro / nanoscale surface roughness structure, and the prepared coating has a higher microstructure strength, is more wear-resistant, and is mildew-proof and lasting, and also has both super-hydrophobic and high-conductivity multifunctional properties.

Description

Technical Field

[0001] The invention belongs to the technical field of wood protection and relates to a preparation scheme and a use method of a long-lasting mildew-proof multifunctional coating. Background Art

[0002] Wood is a versatile, renewable material. Wood species such as Masson pine and rubberwood are susceptible to mold due to their high sugar content. Wood mold typically appears first on the surface and then gradually spreads into the wood's interior. Therefore, simply applying an anti-mold coating to the wood surface offers advantages such as simplicity, high efficiency, and low processing costs, and holds broad application prospects.

[0003] Chinese patent CN 109773926 A discloses a wood and bamboo material with a superhydrophobic, mildew-proof, and anticorrosion coating and a preparation method thereof, including a coating preparation method, a coating impregnation method, and the preparation of the wood and bamboo material with the superhydrophobic, mildew-proof, and anticorrosion coating. The superhydrophobic, mildew-proof, and anticorrosion coating forms a polymethylsiloxane gel film on the surface of the wood and bamboo material, with nano-copper oxide embedded in the polymethylsiloxane gel film. The polymethylsiloxane gel film has a low surface energy, which prevents dust from adhering to the surface and keeps the interface clean. The superhydrophobic interface prevents moisture from entering the wood and bamboo material, maintaining a dry environment and inhibiting mold growth. The nano-copper oxide inhibits microbial growth, achieving the purpose of mildew and corrosion prevention. The coating has great application prospects in fields such as cellulose-based materials. However, the coating has some shortcomings, such as the use of metal oxides that do not conform to people's current pursuit of green living; the mildew-proof performance is low in durability and poor in mechanical wear resistance; and especially with long-term use of the wood and bamboo material, the originally attached coating is easily worn away and subsequently damaged, causing the wood and bamboo material to mold again. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a long-lasting mildew-proof multifunctional coating with long-lasting mildew-proof performance, super hydrophobicity, and environmental friendliness, and a preparation method thereof.

[0005] The present invention is achieved through the following technical solutions:

[0006] A method for preparing a long-lasting mildew-proof multifunctional coating mainly comprises the following steps:

[0007] (1) Melamine (M), urea (U), formaldehyde (F) and deionized water were mixed in proportion, the pH was adjusted to 8.5-9.0 with anhydrous sodium carbonate, heated at 70 °C for 1 h, and diluted with deionized water to obtain MUF prepolymer;

[0008] (2) Cinnamon essential oil, MUF prepolymer, 10 wt % styrene-maleic anhydride copolymer (SMA) solution and deionized water were mixed in proportion, emulsified at 6000 rpm for 20 min using a high-speed disperser, potassium hydrogen phthalate solution was added, and the mixture was kept at 80 °C for 1.5 h to prepare a long-lasting antifungal microcapsule suspension;

[0009] (3) Dissolve polydimethylsiloxane (PDMS) and its curing agent in ethanol and stir at 500 rpm for 30 min to obtain a PDMS modified solution;

[0010] (4) The long-lasting mildew-proof microcapsule suspension in step (2), the PDMS modified solution in step (3), and multi-walled carbon nanotubes (MWCNTs) were mixed in proportion, and stirred at 500 rpm for 30 min under sealed conditions to obtain a long-lasting mildew-proof multifunctional coating.

[0011] Preferably, the melamine (M), urea (U), formaldehyde (F) and deionized water described in step (1) above are mixed in a mass ratio of 1:1:4:4; the mass fraction of the MUF prepolymer obtained after dilution is 10%.

[0012] Preferably, the cinnamon essential oil, MUF prepolymer, 10 wt % styrene-maleic anhydride copolymer (SMA) solution and deionized water described in step (2) above are mixed in a mass ratio of 1:30:7:12; the mass fraction of the potassium hydrogen phthalate solution is 15%, and the mass of the potassium hydrogen phthalate solution is 12 times the mass of the cinnamon essential oil.

[0013] During the stirring and emulsification process, the hydrophobic and hydrophilic groups of the styrene-maleic anhydride copolymer (SMA) solution enter the interior of the cinnamon essential oil and MUF prepolymer solutions, respectively, gradually forming stable emulsion droplets. Due to the negative charge generated by the carboxyl groups on the droplet surface, positively charged small molecules are attracted and gradually form the microcapsule wall material. During this process, the introduced potassium hydrogen phthalate solution not only acts as an acidic catalyst to accelerate the condensation reaction, but also helps maintain the stability of the acidic environment during the microcapsule synthesis process due to its buffering capacity.

[0014] Preferably, when preparing the PDMS modified solution in step (3) above, the mass ratio of polydimethylsiloxane (PDMS), curing agent and ethanol is 1:0.1:20.

[0015] Preferably, in the above step (4), the long-lasting mildew-proof microcapsule suspension, the PDMS modified solution, and the multi-walled carbon nanotubes are mixed in a mass ratio of 1:3:3.

[0016] A method for using a long-lasting mildew-proof multifunctional coating obtained by the preparation method of any of the above claims comprises spraying the long-lasting mildew-proof multifunctional coating on a wood block five times, drying at 80°C for 1 hour, and removing the solvent to obtain a long-lasting mildew-proof multifunctional coating. The coated wood block is then dried at 80°C for 1 hour to remove the hydrophilic groups in the coating and achieve superhydrophobicity.

[0017] Preferably, during spraying, the spraying pressure is 0.3-0.6 MPa and the spraying distance is 20-30 cm. A K3 HVLP spray gun can be used.

[0018] Preferably, before spraying, the wood surface to be sprayed should be cleaned and dried in advance.

[0019] Principle of the present invention:

[0020] (1) Anti-mildew and environmentally friendly: Cinnamon essential oil has broad-spectrum antibacterial activity and, as a green anti-mildew agent, has excellent anti-mildew performance;

[0021] (2) Long-term effect: The present invention adopts an in-situ polymerization method to prepare microcapsules with melamine-urea-formaldehyde as the shell and cinnamon essential oil as the core material. The slow release of cinnamon essential oil is achieved by means of the coating effect of the shell, which prolongs the mildew-proof period to a certain extent. Driven by the electrostatic effect between the negatively charged carboxyl groups on the surface of MWCNT and the positively charged wall material on the surface of the microcapsule, MWCNT is tightly wrapped on the surface of the microcapsule, which will partially bear the friction stress of the microcapsule during the wear resistance process and significantly increase its mechanical strength. That is, MWCNT can protect the internal microcapsules from loss during long-term use, further realizing the long-term stable release of cinnamon essential oil in the microcapsule, thereby achieving a long-term mildew-proof effect.

[0022] (3) Hydrophobicity: Through the electrostatic adsorption effect, microcapsules and multi-walled carbon nanotubes (MWCNTs) synergistically construct a micron / nanoscale surface roughness structure, laying an important foundation for achieving superhydrophobicity; PDMS can be dehydrated and condensed in an ethanol solution to form long silane chains, which are attached to the hydroxyl groups of microcapsules / MWCNTs, significantly reducing the surface energy of the coating, which is one of the keys to achieving superhydrophobicity of the coating; superhydrophobic treatment can significantly reduce the retention of water on the wood surface, thereby enhancing the anti-mildew effect;

[0023] (4) Conductivity: The carboxyl groups introduced on the surface of MWCNTs can attract the positively charged microcapsule wall materials and anchor the microcapsules in the conductive network formed by MWCNTs; some MWCNTs are wrapped around the surface of the microcapsules, forming a more complete conductive network, which reduces the conductive gaps caused by the microcapsules in the conductive network, thus making the wood coating coated with the coating conductive;

[0024] (5) Wear resistance: Driven by the electrostatic interaction between the negatively charged carboxyl groups on the surface of MWCNT and the positively charged wall material on the surface of the microcapsule, MWCNT is tightly wrapped on the surface of the microcapsule, which will partially bear the friction stress of the microcapsule during the wear resistance process and significantly increase its mechanical strength; at the same time, the viscosity of PDMS can make the coating have good adhesion to the wood block and prevent it from falling off.

[0025] Beneficial effects of the present invention:

[0026] 1. The cinnamon essential oil in the present invention is a green mildew preventive with excellent mildew resistance. The cinnamon essential oil encapsulated in the microcapsules can be slowly released through the wall material, thereby achieving long-term mildew resistance while also being environmentally friendly.

[0027] 2. The present invention utilizes microencapsulated plant essential oils and multi-walled carbon nanotubes (MWCNTs) to collaboratively construct a micro- / nanoscale surface roughness structure. The resulting coating has a higher microstructure strength, is more wear-resistant, and is long-lastingly mildew-resistant. It also possesses multifunctional properties such as super-hydrophobicity and high conductivity. The coated wood exhibits advantages such as strong water resistance, pollution resistance, and high durability. It can be widely used in water conservancy, construction, urban gardening, and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 : (a-a2) is the long-lasting mildew-proof microcapsule suspension prepared in Example 1, (b-b2) is the microcapsule / MWCNT coating of Control Example 6, and (c-c2) is the microscopic morphology of the long-lasting mildew-proof multifunctional coating prepared in Example 1;

[0029] Figure 2 : Surface water droplet states of (a) wood, (b) microcapsule / PDMS coating of Control Example 1, (c) MWCNT / PDMS coating of Control Example 2, and (d) microcapsule / MWCNT / PDMS coating of Example 1 in the hydrophobicity test;

[0030] Figure 3 : (a) wood, (b) wood coated with the long-lasting mildew-proof multifunctional coating of Example 1 in an electrically connected state;

[0031] Figure 4 : (a) Wear resistance test of Example 1, (bc) are microscopic morphology images after the wear resistance test of Example 1. DETAILED DESCRIPTION

[0032] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Example

[0033] A method for preparing a long-lasting mildew-proof multifunctional coating mainly comprises the following steps:

[0034] (1) 15 g of melamine (M), 15 g of urea (U), 60 g of formaldehyde (F) and 60 g of deionized water were mixed in proportion, the pH was adjusted to 8.5-9.0 with anhydrous sodium carbonate, heated at 70 °C for 1 h, and diluted with 375 g of deionized water to obtain a 10% MUF prepolymer;

[0035] (2) 0.3 g of cinnamon essential oil, 9 g of MUF prepolymer, 2.1 g of 10 wt % styrene-maleic anhydride copolymer (SMA) solution, and 3.6 g of deionized water were mixed in proportion, emulsified at 6000 rpm for 20 min using a high-speed disperser, 3.6 g of 15 wt % potassium hydrogen phthalate solution was added, and the mixture was kept at 80 °C for 1.5 h to prepare a long-lasting antifungal microcapsule suspension.

[0036] (3) Dissolve polydimethylsiloxane (PDMS) and its curing agent in ethanol and stir at 500 rpm for 30 min to obtain a PDMS modified solution; wherein the mass ratio of polydimethylsiloxane (PDMS), curing agent, and ethanol is 1:0.1:20; the selected curing agent is the commercially available Sylgard 184 curing agent;

[0037] (4) The long-lasting mildew-proof microcapsule suspension in step (2), the PDMS modified solution in step (3), and multi-walled carbon nanotubes (MWCNTs) were mixed in a mass ratio of 1:3:3, and stirred at 500 rpm for 30 min under sealed conditions to obtain a long-lasting mildew-proof multifunctional coating.

[0038] The prepared long-lasting mildew-proof multifunctional coating is used as follows: the long-lasting mildew-proof multifunctional coating is repeatedly sprayed on the surface of a wood block five times. Before spraying, the wood surface to be sprayed is cleaned and dried in the sun. During spraying, a K3 HVLP spray gun is selected, the spraying pressure is 0.3-0.6 MPa, and the spraying distance is 20-30 cm. After spraying, the coating is dried at 80°C for 1 hour to remove the solvent (i.e., remove the water and ethanol in the coating), thereby obtaining a microcapsule / MWCNT / PDMS long-lasting mildew-proof multifunctional coating.

[0039] Comparative Example 1:

[0040] Steps (1) to (3) are exactly the same as those in Example 1. Step (4) is to mix the long-lasting mildew-proof microcapsule suspension in step (2) and the PDMS modified solution in step (3) in a mass ratio of 1:3, and stir at 500 rpm for 30 min under sealed conditions to obtain a microcapsule / PDMS coating.

[0041] The microcapsule / PDMS coating was sprayed repeatedly on the surface of the wood block five times. Before spraying, the wood surface to be sprayed was cleaned and dried in the sun. During spraying, a K3 HVLP spray gun was selected, the spraying pressure was 0.3-0.6 MPa, and the spraying distance was 20-30 cm. After spraying, the coating was dried at 80°C for 1 hour to remove the solvent (i.e., remove the water and ethanol in the coating) to obtain the microcapsule / PDMS coating.

[0042] Comparative Example 2:

[0043] The long-lasting mildew-proof microcapsule suspension preparation step of Example 1 was omitted. Instead, the PDMS modified solution was directly mixed with multi-walled carbon nanotubes (MWCNTs), specifically:

[0044] (1) Dissolve polydimethylsiloxane (PDMS) and its curing agent in ethanol and stir at 500 rpm for 30 min to obtain a PDMS modified solution; wherein the mass ratio of polydimethylsiloxane (PDMS), curing agent, and ethanol is 1:0.1:20;

[0045] (2) The PDMS modified solution in step (1) and multi-walled carbon nanotubes (MWCNTs) were mixed in a mass ratio of 1:1, and stirred at 500 rpm for 30 min under sealed conditions to obtain MWCNT / PDMS coating.

[0046] The MWCNT / PDMS coating was sprayed repeatedly on the surface of the wood block five times. Before spraying, the wood surface to be sprayed was cleaned and dried in the sun. During spraying, a K3 HVLP spray gun was selected, the spraying pressure was 0.3-0.6 MPa, and the spraying distance was 20-30 cm. After spraying, the coating was dried at 80°C for 1 hour to remove the solvent (i.e., remove the water and ethanol in the coating) to obtain the MWCNT / PDMS coating.

[0047] Comparative Example 3:

[0048] The only difference from Example 1 is that the mass ratio of the long-lasting mildew-proof microcapsule suspension, the PDMS modified solution and the multi-walled carbon nanotubes (MWCNT) in step (4) is 1:1:2.

[0049] Comparative Example 4:

[0050] The only difference from Example 1 is that the mass ratio of the long-lasting mildew-proof microcapsule suspension, the PDMS modified solution and the multi-walled carbon nanotubes (MWCNT) in step (4) is 1:1:3.

[0051] Comparative Example 5:

[0052] The only difference from Example 1 is that the mass ratio of the long-lasting mildew-proof microcapsule suspension, the PDMS modified solution and the multi-walled carbon nanotubes (MWCNT) in step (4) is 1:2:3.

[0053] Comparative Example 6:

[0054] Steps (1) to (2) are exactly the same as those in Example 1. Step (3) is to mix the long-lasting mildew-proof microcapsule suspension in step (2) and multi-walled carbon nanotubes (MWCNTs) in a mass ratio of 1:3, and stir at 500 rpm for 30 min under sealed conditions to obtain a microcapsule / MWCNT coating.

[0055] The microcapsule / MWCNT coating was sprayed repeatedly on the surface of the wood block five times. Before spraying, the wood surface to be sprayed was cleaned and dried in the sun. During spraying, a K3 HVLP spray gun was selected, the spraying pressure was 0.3-0.6 MPa, and the spraying distance was 20-30 cm. After spraying, the coating was dried at 80°C for 1 hour to remove the solvent (i.e., remove the water and ethanol in the coating) to obtain the microcapsule / MWCNT coating.

[0056] Performance testing method:

[0057] 1) Micromorphology: The micromorphology of the microcapsules and coatings was observed using a scanning electron microscope (SU 8010) at a voltage of 5 kV.

[0058] 2) Hydrophobicity: The static water wettability of the coating was tested using a contact angle tester (JC 2000D). The test indicators included contact angle (WCA) and sliding angle (SA).

[0059] 3) Anti-mold properties: A spore suspension was prepared using Penicillium citrinum, Trichoderma viride, Aspergillus niger, and a mixed mold. This suspension was evenly applied to a potato / glucose / agar (PDA) solid culture medium and cultured in a climate chamber (25-28°C, 85% relative humidity) for one week to obtain mature colonies. Two sets of wood blocks coated with the coatings from Example 1 and Control Example 2 (without microcapsules), as well as a blank control group, were placed in the culture medium containing the mature colonies. The prepared culture dishes were then placed in a chamber (25-28°C, 85% relative humidity) and the colony growth was regularly observed.

[0060] 4) Conductivity: Dry the coating sample into a powder in an oven at 80°C. Place 1 g of the powder in a universal ammeter (DL334004) at a pressure of 10 MPa. Record the displayed data and convert it into conductivity. Use the universal ammeter and a light bulb to form a power-on test circuit on the coating surface. The coating conductivity can be determined by observing the light status of the light bulb.

[0061] 5) Abrasion resistance: Place 800-grit sandpaper flat on a table. Place the wood sample with the coating facing downward on the sandpaper. Press a 50-g weight on top of the wood sample. Use an external force parallel to the sandpaper plane to pull the wood sample and move it 10 cm. Each back-and-forth movement is considered a treatment cycle. Measure the contact angle (WCA) and sliding angle (SA) after each cycle until the WCA is less than 150°.

[0062] Test result analysis:

[0063] The micromorphology characterization results are as follows Figure 1 The microscopic appearance of the long-lasting antifungal microcapsule suspension prepared by steps (1)-(2) in Example 1 is as follows: Figure 1 As shown in a-a2, the microcapsules are nearly spherical. The microscopic morphology of the microcapsule / MWCNT coating of Comparative Example 6 is shown in Figure 1 As shown in b-b2. Figure 1 As shown in b-b2, the carboxyl groups on the surface of the introduced MWCNTs can attract the positively charged microcapsule wall material and anchor the microcapsules in the conductive network formed by the MWCNTs. The microcapsules and MWCNTs synergistically construct the micro / nano roughness, thereby improving the hydrophobicity of the coating. MWCNTs can protect the internal microcapsules from loss during long-term use, thereby achieving long-term and stable release of cinnamon essential oil in the microcapsules. The microscopic morphology of the long-lasting mildew-proof multifunctional coating prepared in Example 1 is shown in FIG. Figure 1 c-c2. In this composite system, PDMS is evenly coated on the surface of the microcapsule / MWCNT composite material, significantly reducing the surface energy of the coating, which is one of the keys to achieving superhydrophobicity of the coating. Figure 1 It can also be seen in c-c2 that some MWCNTs are also wrapped on the surface of the microcapsules, forming a more complete conductive network, reducing the conductive gaps caused by the microcapsules in the conductive network; and some small-sized microcapsules are attached to the surface of large-sized microcapsules, which not only increases the rough structure of the coating, but also improves the protection of the core material in the microcapsules, which is conducive to achieving long-term mildew prevention.

[0064] The results of the mildew resistance test are shown in Table 1. After 7 days of incubation, Penicillium citrinum, Trichoderma viride, Aspergillus niger, and mixed molds showed obvious signs of growth on the surfaces of the control wood and the MWCNT / PDMS-coated wood, while their growth on the surface of the wood coated with Example 1 was completely inhibited. After 28 days of incubation, no colony growth was observed on the surface of the wood coated with Example 1, indicating that it has excellent long-term mildew resistance. On the one hand, the cinnamon essential oil in Example 1 has broad-spectrum antimicrobial activity, providing an effective protective barrier for wood. On the other hand, the encapsulation effect of the microcapsules in Example 1 reduces the release rate of the cinnamon essential oil, making the coating of Example 1 more durable and mildew-resistant.

[0065] Table 1-1 Anti-mildew test results on Masson pine wood

[0066]

[0067] * “+” means that mold is grown on the surface of the sample, and “-” means that mold is not grown on the surface of the sample.

[0068] Table 1-2 Anti-mildew test results on rubber wood

[0069]

[0070] * “+” means that mold is grown on the surface of the sample, and “-” means that mold is not grown on the surface of the sample.

[0071] The hydrophobicity test results are as follows Figure 2 , as shown in Table 2. Figure 2 As shown in a, since wood contains more hydrophilic groups such as hydroxyl groups, water droplets will quickly penetrate when they contact its surface, resulting in a contact angle of 0°. Figure 2 b) and MWCNT / PDMS of control example 2 ( Figure 2 c) When applied to wood surfaces, the contact angles (WCA) were 137.5° and 145.4°, respectively, indicating hydrophobicity, but not yet reaching the superhydrophobicity requirement (WCA > 150°). This indicates that the addition of microcapsules or MWCNTs alone failed to create the roughness required for superhydrophobicity. To this end, microcapsules and MWCNTs were used to synergistically construct micro / nano-rough structures. The mass ratio of microcapsules, MWCNTs, and PDMS was optimized, and the hydrophobicity test results are shown in Table 2. Table 2 shows that the contact angles of the microcapsule / MWCNT / PDMS coatings (Example 1, Comparative Examples 3, 4, and 5) increased compared to Comparative Examples 1 and 2, indicating further improvement in hydrophobicity. The optimal mass ratio, microcapsules:PDMS:MWCNT = 1:3:3, achieved a contact angle of 157.6°, meeting the superhydrophobicity requirement. Further testing revealed a sliding angle (SA) of 3°, meeting the requirement for superhydrophobic materials (SA < 10°). In summary, in the coating prepared in Example 1, the microcapsules and MWCNTs jointly constructed a micro / nano rough structure, which synergistically acted with the low surface energy provided by PDMS to successfully achieve superhydrophobicity.

[0072] Table 2 Contact angle test results

[0073]

[0074] Conductivity test results are as follows Figure 3, as shown in Table 3. As can be seen from the figure, when no MWCNTs are added, the microcapsule / PDMS coating is non-conductive; when a sufficient number of MWCNTs form a conductive network in the system, the coating becomes conductive (the light bulb becomes brighter). The conductivity results in Table 3 further confirm that the conductivity of the microcapsule / PDMS coating in Control Example 1 is only 0.003, while the conductivity of the coating in Example 1 is as high as 1855.3 S / m. The MWCNT / PDMS coating in Control Example 2 has the highest conductivity (2666.7 S / m), indicating that the addition of microcapsules reduces the conductivity of the coating. As the amount of PDMS used increases, the order of coating conductivity is Control Example 4 > Control Example 5 > Example 1, indicating that the increase in PDMS in the composite system reduces the conductivity of the coating. In Example 1, under the condition of microcapsule:PDMS:MWCNT=1:3:3, the conductivity can still reach 1855.3 S / m, that is, the long-lasting mildew-proof multifunctional coating in the present invention has high conductive functional characteristics. After coating, the wood has stable and long-lasting high conductivity, which can realize the innovative application of wood materials in the fields of electronics, communications, etc.

[0075] Table 3 Conductivity test results

[0076]

[0077] Wear resistance test results are as follows Figure 4 As shown. Figure 4 It can be seen from a that before the wear test, the contact angle (WCA) and sliding angle (SA) of the microcapsule / MWCNT / PDMS coating of Example 1 were 157.6° and 3°, respectively. As the wear test cycles increased, the rough structure and low surface energy structure of the wood surface were gradually destroyed, resulting in a gradual decrease in WCA and a gradual increase in SA until the superhydrophobic function was lost. The microcapsule / MWCNT / PDMS coating of Example 1 can withstand up to 38 wear cycle tests, showing excellent wear resistance. The microscopic morphology of the coating after the wear cycle test is shown in Figure 2. Figure 4 As shown in Fig. 2a, most of the microcapsules were still embedded in the conductive network formed by MWCNTs after the test, indicating that the MWCNTs with good mechanical properties can partially withstand the wear stress to protect the microcapsules during the cyclic test. In addition, under the bonding effect of PDMS, the MWCNTs that were partially damaged during the wear cycle test can still form a complete conductive network ( Figure 4 c). Therefore, the coating constructed by microcapsules, MWCNTs, and PDMS has excellent wear resistance and can be used for a long time in practical applications.

[0078] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiment. All technical solutions based on the concept of the present invention are within the scope of protection of the present invention. It should be noted that for those skilled in the art, various improvements and modifications that do not depart from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a long-lasting mildew-proof multifunctional coating, characterized by: The main steps include: (1) Melamine, urea, formaldehyde and deionized water were mixed in proportion, the pH was adjusted to 8.5-9.0 with anhydrous sodium carbonate, heated at 70 °C for 1 h, and diluted with deionized water to obtain MUF prepolymer; (2) Cinnamon essential oil, MUF prepolymer, 10 wt % styrene-maleic anhydride copolymer solution and deionized water were mixed in proportion, emulsified at 6000 rpm for 20 min using a high-speed disperser, potassium hydrogen phthalate solution was added, and the mixture was kept at 80 °C for 1.5 h to prepare a long-lasting antifungal microcapsule suspension; (3) Dissolve polydimethylsiloxane and its curing agent in ethanol and stir at 500 rpm for 30 min to obtain a PDMS modified solution; (4) The long-lasting mildew-proof microcapsule suspension in step (2), the PDMS modified solution in step (3), and the multi-walled carbon nanotubes were mixed in proportion, and stirred at 500 rpm for 30 min under sealed conditions to obtain a long-lasting mildew-proof multifunctional coating.

2. The method for preparing a long-lasting mildew-proof multifunctional coating according to claim 1, characterized in that: The melamine, urea, formaldehyde and deionized water described in step (1) are mixed in a mass ratio of 1:1:4:4; the mass fraction of the MUF prepolymer obtained after dilution is 10%.

3. The method for preparing a long-lasting mildew-proof multifunctional coating according to claim 1, characterized in that: The cinnamon essential oil, MUF prepolymer, 10 wt % styrene-maleic anhydride copolymer solution and deionized water described in step (2) are mixed in a mass ratio of 1:30:7:12; the mass fraction of the potassium hydrogen phthalate solution is 15%, and the mass of the potassium hydrogen phthalate solution is 12 times the mass of the cinnamon essential oil.

4. The method for preparing a long-lasting mildew-proof multifunctional coating according to claim 1, characterized in that: When preparing the PDMS modified solution in step (3), the mass ratio of polydimethylsiloxane, curing agent and ethanol is 1:0.1:

20.

5. The method for preparing a long-lasting mildew-proof multifunctional coating according to claim 1, characterized in that: In step (4), the long-lasting mildew-proof microcapsule suspension, the PDMS modified solution, and the multi-walled carbon nanotubes are mixed in a mass ratio of 1:3:

3.

6. A method for using a long-lasting mildew-proof multifunctional coating obtained by the preparation method of the long-lasting mildew-proof multifunctional coating according to any one of claims 1 to 5, characterized in that: The long-lasting mildew-proof multifunctional coating was repeatedly sprayed on the surface of the wood block 5 times, dried at 80° C. for 1 hour, and the solvent was removed to obtain a long-lasting mildew-proof multifunctional coating.

7. The method for using the long-lasting mildew-proof multifunctional coating according to claim 6, characterized in that: When spraying, the spraying pressure is 0.3-0.6 MPa and the spraying distance is 20-30 cm.

8. The method for using the long-lasting mildew-proof multifunctional coating according to claim 6, characterized in that: Before spraying, clean the wood surface to be sprayed and let it dry.

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