Waterproof wear-resistant water-based paint for wood and preparation method thereof

Abstract

The invention relates to the technical field of coatings, and discloses a waterproof wear-resistant water-based coating for wood and a preparation method of the waterproof wear-resistant water-based coating. The preparation method of the waterproof wear-resistant water-based paint for the wood comprises the following steps: preparing acrylpimaric acid by taking rosin and acrylic acid as raw materials; the preparation method comprises the following steps: modifying acrylpimaric acid through acylating chlorination, and reacting with 2-amino-2-methyl-1, 3-propylene glycol to obtain rosin-based polyol; preparing nano carbon dots by taking urea and citric acid as raw materials; carrying out modification treatment on the nano carbon dots to obtain hydrophobic modified nano carbon dots; the preparation method comprises the following steps: preparing modified polyurethane by taking polytetrahydrofuran, rosin-based polyol, isophorone diisocyanate, dibutyltin dilaurate and hydrophobic modified nano carbon dots as raw materials; the modified polyurethane, the modified essential oil microcapsules and other components are mixed, and the waterproof and wear-resistant water-based paint for wood is obtained. The waterproof and wear-resistant water-based paint for wood has excellent wear resistance, waterproof performance and antibacterial and mildew-proof performance.

Description

Technical Field

[0001] The invention relates to the technical field of coatings, in particular to a waterproof and wear-resistant water-based coating for wood and a preparation method thereof. Background Art

[0002] Throughout history, wood has been a primary material in construction due to its abundance, ease of processing, and excellent mechanical properties. Today, wood's sustainability makes it a promising alternative to energy-intensive building materials such as steel and concrete, and has attracted significant attention in the fields of construction and building materials research. However, under the influence of ambient moisture, it is susceptible to cracking and deformation due to repeated absorption and desorption of moisture, resulting in strength loss and breakage, and can also promote the growth of bacteria and mold. To enhance the protection of wood, coating the wood surface is a common technique.

[0003] For example, Chinese patent CN104774548B discloses a wood surface protective nanocoating that can be used to protect a variety of wood surfaces, including furniture, building timber structures, outdoor timber structures, and wooden floors. At room temperature, the coating can penetrate deeply into the wood surface, forming a dense, hard, inert protective film on the surface. This film prevents various wood diseases and improves the wood's surface's richness, color saturation, texture, transparency, and surface hardness. It also offers properties such as easy cleaning, stain resistance, water resistance, and wear resistance. However, the antibacterial and mildew-resistant properties of this wood surface protective nanocoating need to be improved. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a method for preparing a waterproof and wear-resistant water-based coating for wood, comprising the following steps:

[0005] Step (1), preparing acrylopimaric acid using rosin and acrylic acid as raw materials; after acrylopimaric acid is modified by chlorination, reacting with 2-amino-2-methyl-1,3-propanediol to obtain rosin-based polyol;

[0006] Step (2), preparing nano-carbon dots using urea and citric acid as raw materials; reacting the nano-carbon dots with silane coupling agent KH-570 and 1H,1H,2H,2H-perfluorodecanethiol in sequence to obtain hydrophobically modified nano-carbon dots;

[0007] Step (3), preparing modified polyurethane using polytetrahydrofuran, rosin-based polyol, isophorone diisocyanate, dibutyltin dilaurate, and hydrophobically modified nanocarbon dots as raw materials;

[0008] Step (4): mixing the modified polyurethane, the modified essential oil microcapsules, deionized water, the defoaming agent, and 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate to obtain a waterproof and wear-resistant water-based coating for wood.

[0009] Preferably, in step (1), the preparation method of the rosin-based polyol is:

[0010] Mix rosin and hydroquinone, raise the temperature to 230-240°C at a rate of 5-10°C / min in a nitrogen atmosphere, then add acrylic acid dropwise at a rate of 0.8-1.2 mL / min. After the addition is complete, maintain the temperature constant for 3-4 hours, and purify to obtain propylene pimaric acid; wherein the mass ratio of rosin, hydroquinone, and acrylic acid is (60-100):(0.2-0.5):(15-30);

[0011] Add propylene pimaric acid and triethylamine to tetrahydrofuran and mix until uniform, then add oxalyl chloride, stir at 4-6°C for 20-40 minutes, then stir at 28-32°C for 2.5-3.5 hours, and purify to obtain chlorinated propylene pimaric acid; wherein the mass ratio of propylene pimaric acid, triethylamine, tetrahydrofuran, and oxalyl chloride is (15-25):(0.1-0.15):(200-300):(20-40);

[0012] 2-amino-2-methyl-1,3-propanediol is added to N,N-dimethylformamide, followed by addition of acyl chloride-modified acrylopimaric acid, and the mixture is heated to 85-95°C for reaction for 20-28 hours, followed by purification to obtain a rosin-based polyol; wherein the mass ratio of 2-amino-2-methyl-1,3-propanediol, N,N-dimethylformamide, and acyl chloride-modified acrylopimaric acid is (2.6-5.2):(100-150):(4.9-9.8);

[0013] In the above process, rosin reacts with acrylic acid using hydroquinone as a polymerization inhibitor to obtain acrylopimaric acid; the carboxyl group in acrylopimaric acid reacts with oxalyl chloride to be chlorinated to obtain acrylopimaric acid modified by chlorination; the acyl chloride of the acrylopimaric acid modified by chlorination then reacts with the amino group of 2-amino-2-methyl-1,3-propanediol to obtain rosin-based polyol.

[0014] Preferably, in step (2), the preparation method of the hydrophobically modified nanocarbon dots is:

[0015] Urea, citric acid, and deionized water were mixed in a mass ratio of (6-12):(0.6-1.2):(20-30), and microwaved at a power of 400-500 W for 5-10 min. The resulting product was dissolved in deionized water and ultrasonicated for about 15-25 min, followed by centrifugation, dialysis, and freeze-drying to obtain nanocarbon dots.

[0016] Add nanocarbon dots to ethanol, then add silane coupling agent KH-570 and deionized water, first stir and react in an ice-water bath for 20-40 minutes, then heat to 50-70°C, stir and react for 1-2 hours, dialyze, and freeze-dry to obtain functionalized nanocarbon dots; wherein the mass ratio of nanocarbon dots, ethanol, silane coupling agent KH-570, and deionized water is 1.5:(12-16):(0.8-1.2):1;

[0017] The functionalized carbon nanodots are added to ethanol and stirred, and then 1H,1H,2H,2H-perfluorodecanethiol is added, and the mixture is heated to 50-60°C. Then, an azobisisobutyronitrile / ethanol solution is added and stirred for 3-5 hours. After the reaction is completed, the mixture is rotary evaporated to obtain hydrophobically modified carbon nanodots; wherein the mass ratio of the functionalized carbon nanodots, 1H,1H,2H,2H-perfluorodecanethiol, and azobisisobutyronitrile / ethanol solution is (1.5-2.5):(0.2-0.6):(4-8);

[0018] In the above process, nanocarbon dots with abundant amino, hydroxyl, and carboxyl groups on their surfaces were successfully synthesized using urea and citric acid as raw materials via microwave-assisted heating. Silanols hydrolyzed with the silane coupling agent KH-570 then condensed with the hydroxyl groups on the nanocarbon dots' surfaces to obtain functionalized nanocarbon dots containing carbon-carbon double bonds. Furthermore, the carbon-carbon double bonds on the functionalized nanocarbon dots' surfaces reacted with the thiol groups of 1H,1H,2H,2H-perfluorodecanethiol to introduce hydrophobic chains onto the nanocarbon dots' surfaces, thereby obtaining hydrophobically modified nanocarbon dots.

[0019] Preferably, in step (3), the preparation method of the modified polyurethane is:

[0020] Add polytetrahydrofuran to butanone, then add rosin-based polyol, stir for 20-30 minutes, add isophorone diisocyanate and dibutyltin dilaurate, heat to 60-80°C and stir to react for 1.5-2.5 hours, then add hydrophobically modified nanocarbon dots, stir to react at 60-80°C for 1.5-2.5 hours, cool to room temperature, and distill to obtain modified polyurethane.

[0021] Preferably, in step (3), the mass ratio of the polytetrahydrofuran, butanone, rosin-based polyol, isophorone diisocyanate, dibutyltin dilaurate, and hydrophobically modified nanocarbon dots is (7.5-18.8):(100-200):(2-6):(2.2-4.4):(0.05-0.08):(1.5-2.5).

[0022] Preferably, in step (4), the contents of the components in the waterproof and wear-resistant water-based coating for wood are, in parts by weight, 30-50 parts of modified polyurethane, 15-25 parts of modified essential oil microcapsules, 100-150 parts of deionized water, 15-30 parts of defoaming agent, and 10-30 parts of 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate; wherein the defoaming agent includes BYK-024 defoaming agent.

[0023] Preferably, in step (4), the method for preparing the modified essential oil microcapsules comprises the following steps:

[0024] Step S1, preparing essential oil microcapsules with chitosan as the wall material and tea tree essential oil as the core material;

[0025] Step S2: treating the multi-walled carbon nanotubes to obtain carboxylated carbon nanotubes; combining the carboxylated carbon nanotubes with essential oil microcapsules to obtain modified essential oil microcapsules.

[0026] Furthermore, in step S1, the preparation method of the essential oil microcapsules is:

[0027] Mix chitosan and 1% acetic acid aqueous solution at a mass ratio of 1:(100-120), stir at 43-48° C. and 500-600 r / min for 50-70 min to obtain a wall material solution;

[0028] Sodium lauryl sulfate, Tween-80, and deionized water are mixed, and tea tree essential oil is added thereto. The mixture is emulsified at 43-48° C. and a rotation speed of 1100-1200 r / min for 50-70 min, and then ultrasonicated for 5-15 min to obtain a core material emulsion. The mass ratio of sodium lauryl sulfate, Tween-80, deionized water, and tea tree essential oil is (1.6-2):(6.4-8):(190-192):2.4.

[0029] The core material emulsion is stirred at 43-48° C. and 500-600 r / min, and the wall material solution is added dropwise to the core material emulsion. The pH of the mixed system is adjusted to 3.9-4.1 with acetic acid, and microencapsulation is performed for 50-70 minutes. Then, a 2% by mass aqueous solution of sodium tripolyphosphate is added dropwise, and cross-linking is performed for 2.5-3.5 hours to obtain a microcapsule dispersion; wherein the mass ratio of the wall material solution, the core material emulsion, and the sodium tripolyphosphate is (100-120):(100-125):0.4;

[0030] The microcapsule dispersion was allowed to stand for 10-14 hours, and essential oil microcapsules were prepared by spray drying, wherein the feed rate of the spray drying was 200 mL / h and the temperature was 110°C;

[0031] In the above process, essential oil microcapsules with chitosan as the wall material and tea tree essential oil as the core material were prepared. The chitosan surface is rich in hydroxyl and amino groups and has certain antibacterial and mildew-proof effects. The main chemical components of tea tree essential oil are monoterpenoid compounds, including 4-terpenol, 1,8-cineole, p-methylisopropylbenzene and γ-terpenes, which have antibacterial and mildew-proof effects. The essential oil microcapsules combining chitosan and tea tree essential oil have excellent antibacterial and mildew-proof effects and can achieve sustained release of tea tree essential oil.

[0032] Furthermore, in step S2, the preparation method of the carboxylated carbon nanotubes comprises mixing multi-walled carbon nanotubes, 92.5% by mass concentrated sulfuric acid, and 68% by mass concentrated nitric acid, condensing and refluxing the mixture, ultrasonically treating the mixture for 5-6 hours, adding deionized water, and purifying the mixture to obtain carboxylated carbon nanotubes; wherein the mass ratio of the multi-walled carbon nanotubes, concentrated sulfuric acid, concentrated nitric acid, and deionized water is (2.5-5):(135-270):(35-70):(200-400);

[0033] In the above process, multi-walled carbon nanotubes are treated with concentrated sulfuric acid and concentrated nitric acid to introduce abundant carboxyl groups on their surface, thereby obtaining carboxylated carbon nanotubes.

[0034] Furthermore, in step S2, the modified essential oil microcapsules are prepared by mixing carboxylated carbon nanotubes, essential oil microcapsules, and deionized water in a mass ratio of 1:(1-1.5):(20-30), stirring at a speed of 400-500 r / min for 20-40 min under sealed conditions, filtering, washing, and drying to obtain modified essential oil microcapsules;

[0035] During the above process, carboxylated carbon nanotubes and essential oil microcapsules are combined through electrostatic and hydrogen bonding, and the carboxylated carbon nanotubes are grafted onto the essential oil microcapsules. Due to the excellent mechanical properties of carbon nanotubes, they provide good protection for the essential oil microcapsules, enhance the mechanical strength of the essential oil microcapsules, and extend their service life. In addition, the carboxylated carbon nanotubes and essential oil microcapsules jointly construct a micro-nano rough structure with a hydrophobic effect.

[0036] The waterproof and wear-resistant water-based paint for wood is prepared by the method for preparing the waterproof and wear-resistant water-based paint for wood.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] 1. Modified polyurethane is included in the waterproof and wear-resistant water-based coating for wood of the present invention, and modified polyurethane realizes the introduction of rosin-based polyol and hydrophobic modified nano-carbon point in the form of chemical bond. Rosin-based polyol contains hydrophobic tricyclic phenanthrene rigid skeleton structure, which is introduced into polyurethane structure. The chemical crosslinking inside polyurethane and tricyclic phenanthrene skeleton structure can improve the hardness, hydrophobicity, density of coating and the bonding force between coating and substrate of modified polyurethane material, thereby improving the waterproof performance and wear resistance of coating; Nano-carbon point has ultraviolet absorption effect, and has inhibitory effect on the growth of bacteria and fungi, is accessed into modified polyurethane, so that modified polyurethane has good anti-ultraviolet performance and antibacterial and mildew-proof performance, further, hydrophobic long chain is introduced on the surface of nano-carbon point, hydrophobicity and cross-linking density of modified polyurethane are improved, thereby improving the wear resistance and waterproof performance of coating.

[0039] 2. Modified essential oil microcapsules are added to the waterproof and wear-resistant water-based coating for wood of the present invention. Chitosan and tea tree essential oil work together to make the essential oil microcapsules have excellent antibacterial and mildew-proof effects, and can achieve sustained release of tea tree essential oil, thereby providing long-term protection for wood. The addition of the essential oil microcapsules can increase the hardness of the coating, thereby improving the wear resistance of the coating. Furthermore, carboxylated carbon nanotubes are connected to the essential oil microcapsules, which have a good protective effect on the essential oil microcapsules, enhance the mechanical strength of the essential oil microcapsules, and improve the wear resistance of the coating. In addition, the carboxylated carbon nanotubes and the essential oil microcapsules jointly construct a micro-nano rough structure with a hydrophobic effect, which works together with the nano-carbon dots to form a hydrophobic micro-nano structure on the wood surface, thereby improving the waterproof effect of the coating.

[0040] 3. The modified polyurethane of the present invention and the surface of the essential oil microcapsules contain abundant polar groups (such as hydroxyl groups and amino groups) that can form hydrogen bonds with wood, and the nano-carbon dots can penetrate into the microporous structure of wood, thereby increasing the bonding strength between the coating and wood and improving the protective effect of the coating on wood. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a comparison chart of the wear mass loss test of the waterproof and wear-resistant water-based coatings for wood prepared in Examples 2-4 of the present invention and Comparative Examples 1-5;

[0042] Figure 2 It is a comparison chart of water contact angle test of the waterproof and wear-resistant water-based coating for wood prepared in Examples 2-4 of the present invention and Comparative Examples 1-5. DETAILED DESCRIPTION

[0043] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0044] Example 1: This example discloses a method for preparing modified essential oil microcapsules, comprising the following steps:

[0045] Step S1, mixing chitosan and 1% acetic acid aqueous solution at a mass ratio of 1:110, stirring at 45° C. and 550 r / min for 60 min to obtain a wall material solution;

[0046] Sodium lauryl sulfate, Tween-80, and deionized water were mixed, and tea tree essential oil was added. The mixture was emulsified at 45°C and a speed of 1100 r / min for 70 minutes, and then ultrasonicated for 10 minutes to obtain a core material emulsion. The mass ratio of sodium lauryl sulfate, Tween-80, deionized water, and tea tree essential oil was 1.8:7.2:191:2.4.

[0047] The core material emulsion was stirred at 550 r / min at 45°C, and the wall material solution was added dropwise to the core material emulsion. The pH of the mixed system was adjusted to 4 with acetic acid, and microencapsulation was performed for 60 minutes. Then, a 2% by mass aqueous solution of sodium tripolyphosphate was added dropwise, and cross-linked for 3 hours to obtain a microcapsule dispersion; wherein the mass ratio of the wall material solution, the core material emulsion, and the sodium tripolyphosphate was 110:115:0.4;

[0048] The microcapsule dispersion was allowed to stand for 12 h, and essential oil microcapsules were prepared by spray drying, wherein the feed rate of the spray drying was 200 mL / h and the temperature was 110°C;

[0049] Step S2, mixing 3.8 g of multi-walled carbon nanotubes, 202.5 g of concentrated sulfuric acid with a mass fraction of 92.5%, and 52.5 g of concentrated nitric acid with a mass fraction of 68%, condensing and refluxing, and ultrasonically treating the mixture for 5.5 h, adding 300 g of deionized water, filtering, and washing the resulting solid product with deionized water and acetone in sequence until neutral, and drying to obtain carboxylated carbon nanotubes;

[0050] Carboxylated carbon nanotubes, essential oil microcapsules, and deionized water were mixed in a mass ratio of 1:1.3:25, stirred at a speed of 450 r / min for 30 min under sealed conditions, filtered, washed, and dried to obtain modified essential oil microcapsules.

[0051] Example 2: This example discloses a method for preparing a waterproof and wear-resistant water-based coating for wood, comprising the following steps:

[0052] Step (1), 60g of rosin and 0.2g of hydroquinone were mixed, and the temperature was raised to 230°C at a rate of 5°C / min in a nitrogen atmosphere, and then 15g of acrylic acid was added dropwise at a rate of 0.8mL / min. After the addition was complete, the temperature was kept constant and the reaction was carried out for 3h. After the reaction was completed, the nitrogen flow rate was increased to remove moisture and volatiles such as unreacted acrylic acid, and the temperature was lowered to 170°C, the material was discharged, cooled to room temperature, ground, washed, and dried to obtain propylene pimaric acid;

[0053] 15 g of propylene pimaric acid and 0.1 g of triethylamine were added to 200 g of tetrahydrofuran and mixed until uniform. 20 g of oxalyl chloride was then added and stirred at 4°C for 40 min and then at 28°C for 3.5 h. After the reaction was completed, solid by-products were removed by filtration. The resulting filtrate was distilled under reduced pressure at 40°C to remove the solvent, and then washed with ethanol and dried to obtain chlorinated propylene pimaric acid.

[0054] 2.6 g of 2-amino-2-methyl-1,3-propanediol was added to 100 g of N,N-dimethylformamide and mixed until uniform. Then, 4.9 g of acyl chloride-modified propylene pimaric acid was added and heated to 85°C for 28 h. After the reaction, the solvent was removed by rotary evaporation at 75°C to obtain a rosin-based polyol.

[0055] Step (2), 6 g of urea and 0.6 g of citric acid were dissolved in 20 g of deionized water, and microwaved at a power of 400 W for 10 min. The resulting product was dissolved in 20 g of deionized water and ultrasonically treated for about 15 min. The insoluble matter was removed by centrifugation. The resulting liquid was dialyzed (500 Da dialysis bag) with deionized water (changed every 24 h) for 40 h, and then freeze-dried at -42 ° C for 50 h to obtain nanocarbon dots;

[0056] Nano-carbon dots were added to ethanol, followed by the addition of silane coupling agent KH-570 and deionized water. The mixture was stirred in an ice-water bath for 20 minutes, then heated to 50°C and stirred for 2 hours. The reaction mixture was dialyzed (500 Da dialysis bag) with deionized water (changed every 24 hours) for 40 hours, and then freeze-dried at -42°C for 50 hours to obtain functionalized nano-carbon dots. The mass ratio of nano-carbon dots, ethanol, silane coupling agent KH-570, and deionized water was 1.5:12:0.8:1.

[0057] 1.5 g of functionalized carbon nanodots were added to 30 g of ethanol and stirred for 20 min. 0.2 g of 1H,1H,2H,2H-perfluorodecanethiol was then added and heated to 50°C. 4 g of a 0.5% azobisisobutyronitrile / ethanol solution was then added and stirred for 5 h. After the reaction was complete, the mixture was rotary evaporated to obtain hydrophobically modified carbon nanodots.

[0058] Step (3), adding 7.5g of polytetrahydrofuran to 100g of butanone, then adding 2g of rosin-based polyol, stirring for 20min, adding 2.2g of isophorone diisocyanate and 0.05g of dibutyltin dilaurate, heating to 60°C and stirring for 2.5h, then adding 1.5g of hydrophobically modified nano-carbon dots, stirring and reacting at 60°C for 2.5h, cooling to room temperature, and distilling to remove the organic solvent to obtain a modified polyurethane;

[0059] Step (4): 30 parts of modified polyurethane, 15 parts of modified essential oil microcapsules, 100 parts of deionized water, 15 parts of BYK-024 defoamer, and 10 parts of 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate are taken in parts by weight and mixed evenly at 30° C. to obtain a waterproof and wear-resistant water-based coating for wood.

[0060] Example 3: This example discloses a method for preparing a waterproof and wear-resistant water-based coating for wood, comprising the following steps:

[0061] Step (1), 100g of rosin and 0.5g of hydroquinone were mixed, heated to 240°C at a rate of 10°C / min in a nitrogen atmosphere, and then 30g of acrylic acid was added dropwise at a rate of 1.2mL / min. After the addition was complete, the temperature was kept constant and reacted for 4h. After the reaction was completed, the nitrogen flow rate was increased to remove moisture and volatiles such as unreacted acrylic acid, and the temperature was lowered to 180°C, the material was discharged, cooled to room temperature, ground, washed, and dried to obtain propylene pimaric acid;

[0062] 25 g of propylene pimaric acid and 0.15 g of triethylamine were added to 300 g of tetrahydrofuran and mixed until uniform. 40 g of oxalyl chloride was then added and stirred at 6° C. for 20 min and then at 32° C. for 2.5 h. After the reaction was completed, solid by-products were removed by filtration. The resulting filtrate was distilled under reduced pressure at 50° C. to remove the solvent, and the filtrate was washed with ethanol and dried to obtain chlorinated propylene pimaric acid.

[0063] 5.2 g of 2-amino-2-methyl-1,3-propanediol was added to 150 g of N,N-dimethylformamide and mixed until uniform. Then, 9.8 g of acyl chloride-modified propylene pimaric acid was added and heated to 95°C for 20 h. After the reaction, the solvent was removed by rotary evaporation at 85°C to obtain rosin-based polyol.

[0064] Step (2), 12 g of urea and 1.2 g of citric acid were dissolved in 30 g of deionized water, and microwaved at a power of 500 W for 5 min. The resulting product was dissolved in 30 g of deionized water and ultrasonically treated for about 25 min. The insoluble matter was removed by centrifugation. The resulting liquid was dialyzed (500 Da dialysis bag) with deionized water (changed every 24 h) for 50 h, and then freeze-dried at -38°C for 45 h to obtain nanocarbon dots;

[0065] Nano-carbon dots were added to ethanol, followed by the addition of silane coupling agent KH-570 and deionized water. The mixture was stirred in an ice-water bath for 40 minutes, then heated to 70°C and stirred for 1 hour. The reaction mixture was dialyzed (500 Da dialysis bag) with deionized water (changed every 24 hours) for 50 hours, and then freeze-dried at -38°C for 45 hours to obtain functionalized nano-carbon dots. The mass ratio of nano-carbon dots, ethanol, silane coupling agent KH-570, and deionized water was 1.5:16:1.2:1.

[0066] 2.5 g of functionalized nano-carbon dots were added to 40 g of ethanol and stirred for 40 min. 0.6 g of 1H,1H,2H,2H-perfluorodecanethiol was added and the mixture was heated to 60°C. 8 g of a 0.5% azobisisobutyronitrile / ethanol solution was added and stirred for 3 h. After the reaction was completed, the mixture was rotary evaporated to obtain hydrophobically modified nano-carbon dots.

[0067] Step (3), adding 18.8g of polytetrahydrofuran to 200g of butanone, then adding 6g of rosin-based polyol, stirring for 30min, adding 4.4g of isophorone diisocyanate and 0.08g of dibutyltin dilaurate, heating to 80°C and stirring for 1.5h, then adding 2.5g of hydrophobically modified nano-carbon dots, stirring and reacting at 80°C for 1.5h, cooling to room temperature, and distilling to remove the organic solvent to obtain a modified polyurethane;

[0068] Step (4): 50 parts of modified polyurethane, 25 parts of modified essential oil microcapsules, 150 parts of deionized water, 30 parts of BYK-024 defoamer, and 30 parts of 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate are taken in parts by weight and mixed uniformly at 40° C. to obtain a waterproof and wear-resistant water-based coating for wood.

[0069] Example 4: This example discloses a method for preparing a waterproof and wear-resistant water-based coating for wood, comprising the following steps:

[0070] Step (1), 80g of rosin and 0.3g of hydroquinone were mixed, heated to 235°C at a rate of 8°C / min in a nitrogen atmosphere, and then 22.5g of acrylic acid was added dropwise at a rate of 1mL / min. After the addition was complete, the temperature was maintained constant and the reaction was carried out for 3.5h. After the reaction was completed, the nitrogen flow rate was increased to remove moisture and volatiles such as unreacted acrylic acid, and the temperature was lowered to 175°C, the material was discharged, cooled to room temperature, ground, washed, and dried to obtain propylene pimaric acid;

[0071] 20 g of propylene pimaric acid and 0.12 g of triethylamine were added to 250 g of tetrahydrofuran and mixed until uniform. 30 g of oxalyl chloride was then added and stirred at 5°C for 30 min and then at 30°C for 3 h. After the reaction was completed, solid by-products were removed by suction filtration. The resulting filtrate was subjected to reduced pressure distillation at 45°C to remove the solvent, and then washed with ethanol and dried to obtain chlorinated modified propylene pimaric acid.

[0072] 3.9 g of 2-amino-2-methyl-1,3-propanediol was added to 125 g of N,N-dimethylformamide and mixed until uniform. Then, 7.4 g of acyl chloride-modified propylene pimaric acid was added and heated to 90°C for 24 h. After the reaction, the solvent was removed by rotary evaporation at 80°C to obtain rosin-based polyol.

[0073] Step (2), 9 g of urea and 0.9 g of citric acid were dissolved in 25 g of deionized water, and microwaved at a power of 450 W for 8 min. The resulting product was dissolved in 25 g of deionized water and ultrasonically treated for about 20 min. The insoluble matter was removed by centrifugation. The resulting liquid was dialyzed (500 Da dialysis bag) with deionized water (changed every 24 h) for 45 h, and then freeze-dried at -40°C for 48 h to obtain nanocarbon dots;

[0074] Nano-carbon dots were added to ethanol, followed by the addition of silane coupling agent KH-570 and deionized water. The mixture was stirred in an ice-water bath for 30 minutes, then heated to 60°C and stirred for 1.5 hours. The reaction mixture was dialyzed (500 Da dialysis bag) with deionized water (changed every 24 hours) for 45 hours, and then freeze-dried at -40°C for 48 hours to obtain functionalized nano-carbon dots. The mass ratio of nano-carbon dots, ethanol, silane coupling agent KH-570, and deionized water was 1.5:14:1:1.

[0075] 2 g of functionalized nano-carbon dots were added to 35 g of ethanol and stirred for 30 min. 0.4 g of 1H,1H,2H,2H-perfluorodecanethiol was then added and heated to 55°C. 6 g of a 0.5% by mass azobisisobutyronitrile / ethanol solution was then added and stirred for 4 h. After the reaction was complete, the mixture was rotary evaporated to obtain hydrophobically modified nano-carbon dots.

[0076] Step (3), adding 13.2 g of polytetrahydrofuran to 150 g of butanone, then adding 4 g of rosin-based polyol, stirring for 25 min, adding 3.3 g of isophorone diisocyanate and 0.07 g of dibutyltin dilaurate, heating to 70 ° C. and stirring for 2 h, then adding 2 g of hydrophobically modified nano-carbon dots, stirring and reacting at 70 ° C. for 2 h, cooling to room temperature, and distilling to remove the organic solvent to obtain a modified polyurethane;

[0077] Step (4): 40 parts of modified polyurethane, 20 parts of modified essential oil microcapsules, 125 parts of deionized water, 22.5 parts of BYK-024 defoamer, and 20 parts of 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate are taken in parts by weight and mixed uniformly at 35° C. to obtain a waterproof and wear-resistant water-based coating for wood.

[0078] The modified essential oil microcapsules in the above Examples 2-4 adopt the modified essential oil microcapsules prepared in Example 1.

[0079] Comparative Example 1:

[0080] Comparative Example 1 Compared with Example 4, in the process of preparing the waterproof and wear-resistant water-based coating for wood in Comparative Example 1, no modified essential oil microcapsules were added, and other conditions remained unchanged.

[0081] Comparative Example 2:

[0082] Comparative Example 2 Compared with Example 4, in the process of preparing the waterproof and wear-resistant water-based coating for wood in Comparative Example 2, essential oil microcapsules were used instead of modified essential oil microcapsules, and other conditions remained unchanged.

[0083] Comparative Example 3:

[0084] Comparative Example 3 Compared with Example 4, in the process of preparing the modified polyurethane in Comparative Example 3, no rosin-based polyol was added, and other conditions remained unchanged.

[0085] Comparative Example 4:

[0086] Comparative Example 4 Compared with Example 4, in the process of preparing the modified polyurethane in Comparative Example 4, no hydrophobically modified nano-carbon dots were added, and other conditions remained unchanged.

[0087] Comparative Example 5:

[0088] Comparative Example 5 Compared with Example 4, in the process of preparing the modified polyurethane in Comparative Example 5, nano-carbon dots were used instead of hydrophobically modified nano-carbon dots, and other conditions remained unchanged.

[0089] In the above examples and comparative examples, multi-walled carbon nanotubes with a diameter of 8 nm and a length of 0.5-2 μm were obtained from Xi'an Qiyue Biotechnology Co., Ltd.; chitosan with a deacetylation degree of 90% was obtained from Xi'an Zhanxun Biotechnology Co., Ltd.; polytetrahydrofuran with a molecular weight of Mn=2000 g / mol and a density of 0.9 g / cm 3, flash point is 58.1℃, boiling point is 195.7℃, from Wuhan Jushun Chemical Co., Ltd.; rosin, acid value 177mgKOH / g, from Guangxi Wuzhou Rosin Co., Ltd.; BYK-024 defoamer, the main component is silicone, the active ingredient content is 96%, appearance: liquid, density is 1.01kg / m3, from Dongguan Haoyouduo New Materials Co., Ltd.; tea tree essential oil, CAS No. 68647-73-4, boiling point 165℃ (lit.), from Jiangxi Zhonghuan Biotechnology Co., Ltd.; Tween-80, CAS No.: 9005-65-6, density (20℃): 1.06~1.11g / ml, saponification value (45~60KOH / g): ≤0.05%, from Shanghai Kanglang Biotechnology Co., Ltd.

[0090] Experimental example:

[0091] The waterproof and wear-resistant water-based coatings for wood prepared in Examples 2-4 and Comparative Examples 1-5 were sprayed onto the wood with a wet coating thickness of 60 μm. The wood samples were dried at room temperature for 8-10 h, and then a second layer of coating (same thickness and drying time) was applied. The performance of the coated wood samples was tested.

[0092] I. Wear Resistance Testing: Wear tests were conducted according to ISO 7784-1-2016 using a wheel covered with sandpaper and a rotary tester. Samples measuring 100 × 100 × 10 mm were mounted on the wear tester and loaded with two 10N grinding wheels. The samples were equilibrated at 23 ± 2°C and 65 ± 5% RH for 7 days before being weighed. After 100 rounds of wear, the samples were reweighed. Wear resistance was determined by mass loss. Three replicates were performed for each test.

[0093] 2. Waterproof performance test: The water contact angle of each group of samples was measured using a water contact angle tester (JC2000D). Each sample was randomly measured 5 times.

[0094] 3. Antibacterial performance test: Escherichia coli and Staphylococcus aureus were selected and tested according to the antibacterial determination method specified in GB / T21866-2020.

[0095] IV. Mildew Resistance Test: This test was conducted in accordance with the relevant provisions of GB / T 18261-2013. The molds used in the test were A. niger, P. citrinum, and T. viride. Mildew resistance levels were determined based on mold coverage, with grades of 0-4 representing 0%, 0-25%, 25-50%, 50-75%, and 75-100% mold coverage of the sample, respectively.

[0096] The test results are shown in Table 1:

[0097] Table 1

[0098]

[0099] It can be seen from the test results in Table 1 that the waterproof and wear-resistant water-based coatings for wood prepared in Examples 2-4 of the present invention have excellent wear resistance, waterproof performance, and antibacterial and mildew resistance. From the comparison of Comparative Examples 1-2 and Example 4, it can be seen that the combination of carboxylated carbon nanotubes and essential oil microcapsules can improve the wear resistance and antibacterial and mildew resistance of the coating, and the carboxylated carbon nanotubes and essential oil microcapsules jointly construct a micro-nano rough structure with a hydrophobic effect, which works together with the nanocarbon dots to form a hydrophobic micro-nano structure on the wood surface, thereby improving the waterproof effect of the coating; from the comparison of Comparative Example 3 and Example 4, it can be seen that the introduction of rosin-based polyols into the polyurethane structure, the chemical crosslinking inside the polyurethane and the presence of the hydrophobic tricyclic phenanthrene rigid skeleton structure improve the wear resistance and waterproof performance of the coating; from the comparison of Comparative Examples 4-5 and Example 4, it can be seen that the nanocarbon dots are connected to the modified polyurethane, so that the modified polyurethane has good antibacterial and mildew resistance. Furthermore, the introduction of hydrophobic long chains on the surface of the nanocarbon dots improves the hydrophobicity and crosslinking density of the modified polyurethane, thereby improving the wear resistance and waterproof performance of the coating.

[0100] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a waterproof and wear-resistant water-based coating for wood, characterized in that: The following steps are involved: Step (1), preparing acrylopimaric acid using rosin and acrylic acid as raw materials; after acrylopimaric acid is modified by chlorination, reacting with 2-amino-2-methyl-1,3-propanediol to obtain rosin-based polyol; Step (2), preparing nano-carbon dots using urea and citric acid as raw materials; reacting the nano-carbon dots with silane coupling agent KH-570 and 1H,1H,2H,2H-perfluorodecanethiol in sequence to obtain hydrophobically modified nano-carbon dots; Step (3), preparing modified polyurethane using polytetrahydrofuran, rosin-based polyol, isophorone diisocyanate, dibutyltin dilaurate, and hydrophobically modified nanocarbon dots as raw materials; Step (4): mixing the modified polyurethane, the modified essential oil microcapsules, deionized water, the defoaming agent, and 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate to obtain a waterproof and wear-resistant water-based coating for wood.

2. The method for preparing a waterproof and wear-resistant water-based coating for wood according to claim 1, wherein: In the step (1), the preparation method of the rosin-based polyol is: Mix rosin and hydroquinone, raise the temperature to 230-240°C in a nitrogen atmosphere, add acrylic acid dropwise, react for 3-4 hours, and purify to obtain propylene pimaric acid; wherein the mass ratio of rosin, hydroquinone, and acrylic acid is (60-100):(0.2-0.5):(15-30); Add propylene pimaric acid and triethylamine to tetrahydrofuran and mix until uniform, then add oxalyl chloride, stir at 4-6°C for 20-40 minutes, then stir at 28-32°C for 2.5-3.5 hours, and purify to obtain chlorinated propylene pimaric acid; wherein the mass ratio of propylene pimaric acid, triethylamine, tetrahydrofuran, and oxalyl chloride is (15-25):(0.1-0.15):(200-300):(20-40); 2-Amino-2-methyl-1,3-propanediol is added to N,N-dimethylformamide, followed by acyl chloride-modified acrylopimaric acid, and the mixture is heated to 85-95°C for 20-28 hours, followed by purification to obtain a rosin-based polyol; wherein the mass ratio of 2-amino-2-methyl-1,3-propanediol, N,N-dimethylformamide, and acyl chloride-modified acrylopimaric acid is (2.6-5.2):(100-150):(4.9-9.8).

3. The method for preparing the waterproof and wear-resistant water-based coating for wood according to claim 1, wherein: In the step (2), the preparation method of the hydrophobically modified nanocarbon dots is: Urea, citric acid, and deionized water were mixed in a mass ratio of (6-12):(0.6-1.2):(20-30), and microwaved at a power of 400-500 W for 5-10 min to purify the mixture to obtain nanocarbon dots. Add nano-carbon dots to ethanol, then add silane coupling agent KH-570 and deionized water, first stir and react in an ice-water bath for 20-40 minutes, then heat to 50-70°C, stir and react for 1-2 hours, and purify to obtain functionalized nano-carbon dots; wherein the mass ratio of nano-carbon dots, ethanol, silane coupling agent KH-570, and deionized water is 1.5:(12-16):(0.8-1.2):1; Functionalized nanocarbon dots are added to ethanol, followed by 1H,1H,2H,2H-perfluorodecanethiol, and the mixture is heated to 50-60°C. Then, azobisisobutyronitrile / ethanol solution is added, and the mixture is stirred for reaction for 3-5 hours. The mixture is purified to obtain hydrophobically modified nanocarbon dots. The mass ratio of the functionalized nanocarbon dots, 1H,1H,2H,2H-perfluorodecanethiol, and azobisisobutyronitrile / ethanol solution is (1.5-2.5):(0.2-0.6):(4-8).

4. The method for preparing a waterproof and wear-resistant water-based coating for wood according to claim 1, wherein: In the step (3), the preparation method of the modified polyurethane is: Add polytetrahydrofuran to butanone, then add rosin-based polyol, stir, add isophorone diisocyanate and dibutyltin dilaurate, heat to 60-80°C and stir to react for 1.5-2.5 hours, then add hydrophobically modified nanocarbon dots, stir and react at 60-80°C for 1.5-2.5 hours to obtain a modified polyurethane; wherein the mass ratio of the polytetrahydrofuran, butanone, rosin-based polyol, isophorone diisocyanate, dibutyltin dilaurate, and hydrophobically modified nanocarbon dots is (7.5-18.8):(100-200):(2-6):(2.2-4.4):(0.05-0.08):(1.5-2.5).

5. The method for preparing a waterproof and wear-resistant water-based coating for wood according to claim 1, wherein: In the step (4), the contents of the components in the waterproof and wear-resistant water-based coating for wood are, in parts by weight, 30-50 parts of modified polyurethane, 15-25 parts of modified essential oil microcapsules, 100-150 parts of deionized water, 15-30 parts of defoaming agent, and 10-30 parts of 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate; wherein the defoaming agent includes BYK-024 defoaming agent.

6. The method for preparing a waterproof and wear-resistant water-based coating for wood according to claim 1, wherein: In the step (4), the method for preparing the modified essential oil microcapsules comprises the following steps: Step S1, preparing essential oil microcapsules with chitosan as the wall material and tea tree essential oil as the core material; Step S2: treating the multi-walled carbon nanotubes to obtain carboxylated carbon nanotubes; combining the carboxylated carbon nanotubes with essential oil microcapsules to obtain modified essential oil microcapsules.

7. The method for preparing a waterproof and wear-resistant water-based coating for wood according to claim 6, characterized in that: In step S1, the preparation method of the essential oil microcapsules is: Mix chitosan and 1% acetic acid aqueous solution at a mass ratio of 1:(100-120), and stir at 43-48° C. for 50-70 minutes to obtain a wall material solution; Sodium lauryl sulfate, Tween-80, deionized water, and tea tree essential oil were mixed in a mass ratio of (1.6-2):(6.4-8):(190-192):2.4, emulsified at 43-48° C. for 50-70 min, and then ultrasonicated for 5-15 min to obtain a core material emulsion; The core material emulsion is stirred at 43-48° C., and the wall material solution is added dropwise, the pH of the mixed system is adjusted to 3.9-4.1, and the microencapsulation treatment is carried out for 50-70 minutes. Then, an aqueous sodium tripolyphosphate solution is added dropwise, and cross-linking is carried out for 2.5-3.5 hours to obtain a microcapsule dispersion. The microcapsule dispersion is allowed to stand for 10-14 hours, and essential oil microcapsules are prepared by spray drying; wherein the mass ratio of the wall material solution, the core material emulsion, and the sodium tripolyphosphate is (100-120):(100-125):0.

4.

8. The method for preparing the waterproof and wear-resistant water-based coating for wood according to claim 6, characterized in that: In step S2, the preparation method of the carboxylated carbon nanotubes comprises mixing multi-walled carbon nanotubes, concentrated sulfuric acid, and concentrated nitric acid, condensing and refluxing, and ultrasonically treating for 5-6 hours, adding deionized water, and purifying to obtain carboxylated carbon nanotubes; wherein the mass ratio of the multi-walled carbon nanotubes, concentrated sulfuric acid, concentrated nitric acid, and deionized water is (2.5-5):(135-270):(35-70):(200-400).

9. The method for preparing a waterproof and wear-resistant water-based coating for wood according to claim 6, characterized in that: In step S2, the modified essential oil microcapsules are prepared by mixing carboxylated carbon nanotubes, essential oil microcapsules, and deionized water in a mass ratio of 1:(1-1.5):(20-30), stirring at a speed of 400-500 r / min for 20-40 minutes under sealed conditions, and purifying to obtain modified essential oil microcapsules.

10. A waterproof and wear-resistant water-based coating for wood prepared by the method for preparing a waterproof and wear-resistant water-based coating for wood according to any one of claims 1 to 9.

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