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

Abstract

The invention discloses a preparation method and a use method of a long-acting mildew-proof multifunctional coating, and the preparation method comprises the following steps: mixing melamine, urea, formaldehyde and deionized water in proportion to prepare an MUF prepolymer, mixing the MUF prepolymer with cinnamon essential oil, a 10wt% styrene-maleic anhydride copolymer solution and deionized water to prepare a long-acting mildew-proof microcapsule suspension, and carrying out spray drying on the long-acting mildew-proof microcapsule suspension to prepare the long-acting mildew-proof multifunctional coating. And finally, mixing the long-acting mildew-proof microcapsule suspension, the PDMS modified solution and the multi-walled carbon nanotubes to prepare the long-acting mildew-proof multifunctional coating. When in use, the long-acting mildew-proof multifunctional coating is repeatedly sprayed on the surface of a wood block for five times, and is dried at 80 DEG C for 1 hour, and the long-acting mildew-proof multifunctional coating is formed after the solvent is removed. The microencapsulated plant essential oil and the multi-walled carbon nanotubes are utilized to synergistically construct a micro / nano-scale surface rough structure, and the prepared coating is higher in fine structure strength, more wear-resistant, lasting in mildew resistance, and also has the multifunctional characteristics of super-hydrophobicity and high conductivity.

Description

Technical Field

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

[0002] Wood is a versatile renewable material. Masson pine, rubber wood and other materials are prone to mildew due to their high sugar content. Wood mildew generally appears on the surface of the wood first and then gradually spreads to the inside. Therefore, simply applying an anti-mildew coating on the surface of the wood to protect it has the advantages of simple process, high efficiency and low processing cost, and has broad application prospects.

[0003] Chinese patent CN 109773926 A discloses a wood and bamboo material with a super-hydrophobic mildew and anti-corrosion coating and a preparation method thereof, including a coating preparation method, a coating impregnation method, and the preparation of wood and bamboo material with a super-hydrophobic mildew and anti-corrosion coating. The prepared super-hydrophobic mildew and anti-corrosion coating forms a layer of polymethylsiloxane gel film on the surface of the wood and bamboo material, wherein the nano-copper oxide is embedded in the polymethylsiloxane gel film; the polymethylsiloxane gel film has a low surface energy, which can prevent dust in the air from adhering and keep the interface clean; the super-hydrophobic interface can prevent external moisture from entering the wood and bamboo material, maintain a dry environment, and inhibit the growth of mold; the nano-copper oxide plays a role in inhibiting the growth of microorganisms, achieving the purpose of mildew and anti-corrosion, and has great application prospects in the fields of cellulose-based materials. However, the coating has some shortcomings, such as the use of metal oxides does not meet the current people's pursuit of green life; the durability of mildew resistance is low and the mechanical wear resistance is poor; especially in the long-term use of wood and bamboo, the originally attached coating is easy to be worn and then destroyed, causing the wood and bamboo 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 which is super hydrophobic and environmentally friendly and has a long-lasting mildew-proof performance and a preparation method thereof.

[0005] The present invention is achieved through the following technical solutions: A method for preparing a long-lasting mildew-proof multifunctional coating mainly comprises the following steps: (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; (2) Cinnamon essential oil, MUF prepolymer, 10wt% 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; (3) Dissolve polydimethylsiloxane (PDMS) 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 multi-walled carbon nanotubes (MWCNTs) are mixed in proportion, and stirred at 500 rpm for 30 min under sealed conditions to obtain a long-lasting mildew-proof multifunctional coating.

[0006] 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%.

[0007] Preferably, the cinnamon essential oil, MUF prepolymer, 10wt% styrene-maleic anhydride copolymer (SMA) solution and deionized water described in the above 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.

[0008] During the stirring emulsification process, the hydrophobic groups and hydrophilic groups of the styrene-maleic anhydride copolymer (SMA) solution entered 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 were attracted to gradually form microcapsule wall materials; in this process, the introduced potassium hydrogen phthalate solution can not only act as an acidic catalyst to accelerate the condensation reaction, but also help maintain the stability of the acidic environment during the microcapsule synthesis process due to its buffering capacity.

[0009] 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.

[0010] Preferably, in the above step (4), the long-acting mildew-proof microcapsule suspension, the PDMS modified solution, and the multi-walled carbon nanotubes are mixed in a mass ratio of 1:3:3.

[0011] The method for using the long-term mildew-proof multifunctional coating obtained by the preparation method of the long-term mildew-proof multifunctional coating described in any one of the above claims is to repeatedly spray the long-term mildew-proof multifunctional coating on the surface of the wood block for 5 times, dry it at 80°C for 1 hour, remove the solvent, and obtain a long-term mildew-proof multifunctional coating. The wood block coated with the coating is dried at 80°C for 1 hour to remove the hydrophilic groups in the coating and achieve super hydrophobicity.

[0012] Preferably, during spraying, the spraying pressure is 0.3-0.6 MPa, the spraying distance is 20-30 cm, and a K3 HVLP spray gun can be used.

[0013] Preferably, before spraying, the wood surface to be sprayed is cleaned and dried in advance.

[0014] Principle of the present invention: (1) Anti-mildew and environmentally friendly: Cinnamon essential oil has a broad-spectrum antibacterial activity and, as a green anti-mildew agent, has excellent anti-mildew properties; (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 virtue 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. (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 dehydrate and condense 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; (4) Conductivity: The carboxyl groups introduced on the surface of MWCNT can attract the positively charged microcapsule wall material and anchor the microcapsules in the conductive network formed by MWCNT; some MWCNTs are wrapped on the surface of the microcapsules to form a more complete conductive network, which reduces the conductive gap caused by the microcapsules in the conductive network, so that the wood coating coated with the coating has conductivity; (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, the 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 with the wood block and prevent it from falling off.

[0015] Beneficial effects of the present invention: 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 microcapsule can be slowly released through the wall material, thereby achieving long-term mildew resistance and environmental friendliness.

[0016] 2. The present invention utilizes microencapsulated plant essential oil and multi-walled carbon nanotubes (MWCNT) to collaboratively construct a micro / nano-scale surface roughness structure. The prepared coating has a higher microstructure strength, is more wear-resistant, and is long-lastingly mildew-proof. It also has super-hydrophobic and highly conductive multifunctional properties. After coating, the wood has the advantages of 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

[0017] 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; Figure 2 : Surface water drop 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; Figure 3 : (a) wood, (b) the electrical connection state of wood with the long-lasting mildew-proof multifunctional coating of Example 1; Figure 4 : (a) Wear resistance test of Example 1, (bc) are microscopic morphology images after the wear resistance test of Example 1. DETAILED DESCRIPTION

[0018] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. Example

[0019] A method for preparing a long-lasting mildew-proof multifunctional coating mainly comprises the following steps: (1) 15 g melamine (M), 15 g urea (U), 60 g formaldehyde (F) and 60 g 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 deionized water to obtain a MUF prepolymer with a mass fraction of 10%; (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; (3) Dissolve polydimethylsiloxane (PDMS) and its curing agent in ethanol, stir at 500 rpm for 30 min, and 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; (4) The long-lasting mildew-proof microcapsule suspension in step (2), the PDMS modified solution in step (3), and multi-walled carbon nanotubes (MWCNT) are 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.

[0020] The method for using the prepared long-lasting mildew-proof multifunctional coating is as follows: the long-lasting mildew-proof multifunctional coating is repeatedly sprayed on the surface of a wood block for 5 times. Before spraying, the surface of the wood to be sprayed is cleaned and dried in the sun. When 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) to obtain a microcapsule / MWCNT / PDMS long-lasting mildew-proof multifunctional coating.

[0021] Comparative Example 1: 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.

[0022] The microcapsule / PDMS coating was sprayed repeatedly on the surface of the wood block for 5 times. Before spraying, the wood surface to be sprayed was cleaned and dried in advance. When 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, it was dried at 80°C for 1 hour to remove the solvent (i.e., remove the water and ethanol in the coating) to obtain a microcapsule / PDMS coating.

[0023] Comparative Example 2: The long-lasting mildew-proof microcapsule suspension preparation step of Example 1 is omitted, but the PDMS modified solution is directly mixed with multi-walled carbon nanotubes (MWCNT), specifically: (1) Dissolve polydimethylsiloxane (PDMS) and its curing agent in ethanol, stir at 500 rpm for 30 min, and obtain a PDMS modified solution; wherein the mass ratio of polydimethylsiloxane (PDMS), curing agent, and ethanol is 1:0.1:20; (2) The PDMS modified solution in step (1) and multi-walled carbon nanotubes (MWCNT) were mixed in a mass ratio of 1:1, and stirred at 500 rpm for 30 min under sealed conditions to obtain a MWCNT / PDMS coating.

[0024] The MWCNT / PDMS coating was sprayed repeatedly on the surface of the wood block for 5 times. Before spraying, the wood surface to be sprayed was cleaned and dried in advance. When 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, it 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.

[0025] Comparative Example 3: 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.

[0026] Comparative Example 4: 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.

[0027] Comparative Example 5: 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.

[0028] Comparative Example 6: 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 (MWCNT) in a mass ratio of 1:3, and stir at 500 rpm for 30 min under sealed conditions to obtain a microcapsule / MWCNT coating.

[0029] The microcapsule / MWCNT coating was sprayed repeatedly on the surface of the wood block for 5 times. Before spraying, the wood surface to be sprayed was cleaned and dried in the sun. When 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, it was dried at 80°C for 1 hour to remove the solvent (i.e., remove the water and ethanol in the coating) to obtain a microcapsule / MWCNT coating.

[0030] Performance testing method: 1) Micromorphology: The micromorphology of the microcapsules and coatings was observed using a scanning electron microscope (SU 8010) at a voltage of 5 kV.

[0031] 2) Hydrophobicity: The static water wetting ability of the coating was tested using a contact angle tester (JC 2000D). The test indicators included contact angle (WCA) and sliding angle (SA).

[0032] 3) Anti-mold performance: spore suspension was prepared using Penicillium citrinum, Trichoderma viride, Aspergillus niger and mixed molds, and evenly coated on the surface of potato / glucose / agar (PDA) solid culture medium, and cultured in a climate box (temperature 25-28°C, relative humidity 85%) for one week to obtain mature colonies; two groups of wood blocks coated with the coating of Example 1 and Control Example 2 (without microcapsule structure) and a blank control group were placed in the cultured mature colony culture medium. Then the prepared culture dish was placed in a chamber (temperature 25-28°C, relative humidity 85%), and the colony growth was observed regularly.

[0033] 4) Conductivity: Dry the coating sample into powder in an oven at 80°C, take 1 g of the powder and put it into a universal meter (DL334004 model), set the pressure to 10 MPa, record the displayed data and convert it into conductivity; use the universal meter and a light bulb to form a power-on test circuit on the coating surface, and judge the conductivity of the coating by the lighting state of the light bulb.

[0034] 5) Abrasion resistance: Place 800-grit sandpaper flat on the table, keep the coating of the wood block sample facing down on the sandpaper, press a 50-gram weight on the wood block sample, use an external force parallel to the sandpaper plane to pull the wood block and move it 10 cm. Each back and forth movement is regarded as a treatment cycle. Test the contact angle (WCA) and rolling angle (SA) after each cycle until WCA < 150°.

[0035] Test result analysis: The microscopic morphology characterization results are as follows Figure 1 The microscopic appearance of the long-lasting antifungal microcapsule suspension prepared by steps (1) to (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 b-b2. Figure 1 b-b2 shows that the carboxyl groups on the surface of the introduced MWCNT can attract the positively charged microcapsule wall material and anchor the microcapsules in the conductive network formed by the MWCNT. The microcapsules and MWCNTs synergistically construct the micro / nano roughness, thereby improving the hydrophobicity of the coating. MWCNT 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 uniformly 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 from c-c2 that some MWCNTs are also wrapped on the surface of the microcapsules to form 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 beneficial to achieve long-term mildew prevention.

[0036] The results of the mildew resistance test are shown in Table 1. After 7 days of cultivation, 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 the growth on the surface of the wood coated in Example 1 was completely inhibited. After 28 days of cultivation, no colony growth was observed on the surface of the wood coated in Example 1, indicating that it has excellent long-term mildew resistance. On the one hand, the cinnamon essential oil in Example 1 has a broad-spectrum antibacterial activity and provides an effective protective barrier for wood. On the other hand, the coating effect of the microcapsules in Example 1 reduces the release rate of the cinnamon essential oil, making the coating in Example 1 have a more lasting mildew resistance.

[0037] Table 1-1 Anti-mildew test results on Masson pine wood

[0038] * “+” means that mold is grown on the surface of the sample, and “-” means that mold is not grown on the surface of the sample.

[0039] Table 1-2 Anti-mildew test results on rubber wood

[0040] * “+” means that mold is grown on the surface of the sample, and “-” means that mold is not grown on the surface of the sample.

[0041] 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 coated on the wood surface, the contact angles (WCA) were 137.5° and 145.4°, respectively, showing hydrophobicity, but not yet reaching the super-hydrophobic (WCA>150°) requirement. This shows that the addition of microcapsules or MWCNTs alone failed to construct a rough structure required for super-hydrophobicity. To this end, microcapsules and MWCNTs were further used to synergistically construct micro / nano rough structures, and the mass ratio of microcapsules, MWCNTs and PDMS was optimized. The hydrophobicity test results are shown in Table 2. As can be seen from Table 2, the contact angles of the microcapsules / MWCNT / PDMS coatings (Example 1, Comparative Examples 3, 4 and 5) increased compared to Comparative Examples 1 and 2, indicating that the hydrophobic performance has been further improved. Among them, the best mass ratio is microcapsules: PDMS: MWCNT = 1:3:3, and the contact angle reaches 157.6°, which meets the super-hydrophobic conditions. Further testing shows that its sliding angle (SA) is 3°, which meets the requirements of super-hydrophobic materials (SA<10°). In summary, in the coating prepared in Example 1, microcapsules and MWCNTs jointly constructed a micro / nano rough structure, which synergistically acted with the low surface energy provided by PDMS to successfully obtain superhydrophobicity.

[0042] Table 2 Contact angle test results

[0043]

[0044] The conductivity test results are as follows: Figure 3 , as shown in Table 3. As can be seen from the figure, when MWCNT is not added, the microcapsule / PDMS coating is not conductive; when enough MWCNT forms 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 of Control Example 1 is only 0.003, while the conductivity of the coating of Example 1 is as high as 1855.3 S / m. The conductivity of the MWCNT / PDMS coating of Control Example 2 (2666.7 S / m) is the highest, indicating that the addition of microcapsules will reduce the conductivity of the coating. With the change of the amount of PDMS used, the order of the conductivity of the coating is Control Example 4>Control Example 5>Example 1, indicating that the increase of PDMS in the composite system will reduce 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, and the wood after coating has stable and lasting high conductivity, which can realize innovative applications of wood materials in electronics, communications and other fields.

[0045] Table 3 Conductivity test results

[0046] The wear resistance test results are as follows: Figure 4 As shown. Figure 4 It can be seen 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 cycle increases, the rough structure and low surface energy structure of the wood surface are gradually destroyed, resulting in a gradual decrease in WCA and a gradual increase in SA until the superhydrophobic function is 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 bc, most of the microcapsules are still embedded in the conductive network formed by MWCNTs after the test, indicating that MWCNTs with good mechanical properties can partially withstand the wear stress to protect the microcapsules during the cycle 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.

[0047] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing a long-lasting mildew-proof multifunctional coating, characterized in that: 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 are 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, 10wt% 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-acting mildew-proof multifunctional coating obtained by the preparation method of the long-acting mildew-proof multifunctional coating according to any one of claims 1 to 5, characterized in that: The long-lasting anti-mildew multifunctional coating was repeatedly sprayed on the surface of the wood block for 5 times, dried at 80° C. for 1 hour, and the solvent was removed to obtain a long-lasting anti-mildew 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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