Wear-resistant and pressure-resistant laminated bamboo plywood and preparation method thereof

Abstract

The application discloses wear-resistant and pressure-resistant film-coated bamboo plywood and a preparation method thereof, and relates to the technical field of bamboo plywood. The preparation method comprises the following steps: weaving modified bamboo pieces into bamboo mats, then stacking one bamboo mat on one film-coated paper, stacking one film-coated paper on the bamboo mat, continuously stacking two to four bamboo mats and two to four film-coated papers in sequence, and then carrying out hot-pressing treatment, pressure and temperature maintaining at 50-60 DEG C, sanding and edge finishing after pressure and temperature decreasing, so as to obtain the wear-resistant and pressure-resistant film-coated bamboo plywood; the film-coated paper is prepared from imidazole, phytic acid and itaconic acid-based epoxy resin. The modified bamboo pieces treated by sodium hydroxide, sodium sulfite, diammonium hydrogen phosphate and sodium silicate aqueous solution effectively improve the wear resistance, pressure resistance, flame resistance, mildew resistance and moisture resistance of the bamboo plywood; the introduction of the film-coated paper further improves the wear resistance, pressure resistance, flame resistance, mildew resistance and moisture resistance. Therefore, the application has a wider application prospect.

Description

Technical Field

[0001] This invention relates to the field of bamboo plywood technology, specifically to a wear-resistant and pressure-resistant coated bamboo plywood and its preparation method. Background Technology

[0002] Bamboo plywood is a multi-layered board made primarily from bamboo. After processing bamboo into pieces through cutting, slicing, steaming, and drying, the bamboo strips are arranged in a crisscross pattern according to their grain and bonded together with adhesives (such as phenolic resin or urea-formaldehyde resin) under heat and pressure. Due to its high cost-effectiveness, lightweight yet high strength, good environmental friendliness, and ease of processing, bamboo plywood is widely used in furniture manufacturing, vehicle bodies, large machinery packaging, mining ventilation doors, refrigerated truck floors, stage flooring, and many other fields.

[0003] However, in practical applications, bamboo plywood still suffers from problems such as high moisture absorption, making it prone to mold and delamination when exposed to humid environments for extended periods; and poor fire resistance, making it easily ignited. Therefore, the moisture resistance, mold resistance, and flame retardancy of existing aluminum-coated base paper still need to be improved. Summary of the Invention

[0004] The purpose of this invention is to provide a wear-resistant and pressure-resistant coated bamboo plywood and its preparation method, thereby solving the following technical problems:

[0005] Existing bamboo plywood still suffers from poor moisture resistance, mildew resistance, and flame retardancy.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A method for preparing wear-resistant and pressure-resistant coated bamboo plywood includes the following steps:

[0008] Modified bamboo strips are woven into bamboo mats. Then, one bamboo mat is placed on a sheet of coated paper, and another sheet of coated paper is placed on top of the bamboo mat. This process is repeated, with 2-4 bamboo mats and 4 sheets of coated paper placed on top of each other. The mats are then hot-pressed at 120-130℃ and 2-3MPa for 10-20 minutes, followed by pressure holding at 50-60℃ for 10-20 minutes. After depressurization and cooling, the mats are sanded and the edges are trimmed to obtain wear-resistant and pressure-resistant coated bamboo plywood.

[0009] Preferably, the modified bamboo strips are prepared using the following method:

[0010] A1: Dissolve sodium hydroxide and sodium sulfite in deionized water, then immerse bamboo strips with a thickness of 0.1-0.5 cm and stir at 80-90℃ for 3-6 hours. After filtration, rinse the bamboo strips with deionized water 8-10 times, and then dry at 65-70℃ for 10-15 hours to obtain pretreated bamboo strips.

[0011] A2: Add deionized water and silane coupling agent KH-550 to anhydrous ethanol and stir for 30-50 min. Adjust the pH to 4.5-5.0 and then immerse the pretreated bamboo strips in the solution. Shake at 70-90 times / min for 2-3 h at 45-50℃. Remove the bamboo strips and ultrasonically clean them with deionized water for 3-5 times, 3-5 min each time. Finally, vacuum dry them at 55-60℃ for 10-15 h to obtain aminated bamboo strips.

[0012] A3: Dissolve diammonium hydrogen phosphate in deionized water and ultrasonically disperse for 15-30 minutes. Then, immerse it in aminated bamboo strips and vacuum impregnate it. After removing the bamboo strips, hang them vertically for 30-60 minutes and then dry them at 45-50℃ for 2-4 hours to obtain flame-retardant bamboo strips.

[0013] A4: Immerse the flame-retardant bamboo strips in a sodium silicate aqueous solution and perform vacuum impregnation treatment. After removing the bamboo strips, hang them vertically for 30-60 minutes, and then dry them at 45-50℃ for 2-4 hours to obtain mineralized bamboo strips.

[0014] A5: Add tetraethyl orthosilicate, trimethylethoxysilane, and methanol to deionized water and stir for 1-2 hours. Then adjust the pH to 11-12 with 25%-28% ammonia solution. Then add 180-220 g / m³ of the solution. 2 The coating amount is evenly spin-coated onto the surface of the mineralized bamboo strips, and after curing treatment, modified bamboo strips are obtained.

[0015] Preferably, the mass ratio of deionized water, sodium hydroxide, and sodium sulfite in A1 is 600-700:10-20:8-16;

[0016] The mass ratio of anhydrous ethanol, deionized water, and silane coupling agent KH-550 in A2 is 90-135:10-15:2-3.

[0017] Preferably, the mass ratio of diammonium hydrogen phosphate to deionized water in A3 is 22.8-34.2:400-600;

[0018] The vacuum impregnation treatment described in A3 is as follows: after impregnation for 5-10 minutes under a vacuum of -0.09 MPa, degas the solution, repeat the cycle 5-7 times, and then impregnate for 10-15 hours under a vacuum of -0.09 MPa.

[0019] Preferably, the sodium silicate aqueous solution in A4 has a mass fraction of 5%-10%;

[0020] The vacuum impregnation treatment described in A4 is as follows: after impregnation for 5-10 minutes under a vacuum of -0.09 MPa, degas the solution, repeat the cycle 5-7 times, and then impregnate for 4-12 hours under a vacuum of -0.09 MPa.

[0021] Preferably, the mass ratio of deionized water, tetraethyl orthosilicate, trimethylethoxysilane, and methanol in A5 is 100-120:50-60:20-24:20-24;

[0022] The curing process described in A5 is as follows: first, pre-curing at 60-80℃ for 2-4 hours, and then curing at 130-140℃ and 0.2-0.5MPa pressure for 2-3 hours.

[0023] Preferably, the method for preparing the coated paper is as follows:

[0024] B1: Dissolve phytic acid in deionized water to obtain a phytic acid dispersion;

[0025] B2: Dissolve imidazole in deionized water, then add phytic acid dispersion dropwise and stir for 8-10 hours. Then, rotary evaporate under reduced pressure at 55-65℃ for 70-90 minutes to obtain the curing agent.

[0026] B3: Add itaconic acid and potassium carbonate to N,N-dimethylformamide and stir for 30-40 min. Then, add allyl bromide dropwise and react at 55-65℃ for 10-15 h. Then, add deionized water at 5-15℃ and stir for 20-40 min. Extract with dichloromethane 3-5 times and wash the extract with deionized water 5-7 times. Finally, add anhydrous magnesium sulfate to dry the organic phase, stir for 10-30 min and filter. The filtrate is first rotary evaporated at 38-42℃ for 1-2 h, and then vacuum dried at 55-60℃ for 20-25 h to obtain modified itaconic acid.

[0027] B4: Dissolve the modified itaconic acid in dichloromethane to obtain a modified itaconic acid dispersion;

[0028] B5: Dissolve m-chloroperoxybenzoic acid in dichloromethane, then add it dropwise to the modified itaconic acid dispersion and react at 30-40℃ for 90-100h. After filtration, wash the solution 3-5 times with 5% sodium thiosulfate, then wash 3-5 times each with saturated sodium bicarbonate solution and saturated sodium chloride solution. Then add anhydrous magnesium sulfate to dry the organic phase, stir for 10-30min and filter. The filtrate is first rotary evaporated under reduced pressure at 35-40℃ for 2-3h, and then vacuum dried at 55-60℃ for 4-8h to obtain itaconic acid-based epoxy resin.

[0029] B6: Add curing agent to itaconic acid-based epoxy resin and stir for 40-60 minutes, then degas for 20-30 minutes under a gauge pressure of -0.095 MPa, and then apply 180-220 g / m³ of curing agent. 2 The coating amount is evenly spin-coated onto the surface of the film-forming plate, and after gradient curing, the film is removed to obtain the coated paper.

[0030] Preferably, the mass ratio of phytic acid to deionized water in B1 is 10-12:40-50;

[0031] The mass ratio of imidazole, deionized water, and phytic acid dispersion in B2 is 7.5-9:40-50:50-62.

[0032] Preferably, the mass ratio of N,N-dimethylformamide, itaconic acid, potassium carbonate, allyl bromide, deionized water, and anhydrous magnesium sulfate in B3 is 50-60:25-30:58.5-70.5:27-32:300-350:5-10;

[0033] The mass ratio of modified itaconic acid to dichloromethane in B4 is 23-30:200-250;

[0034] The mass ratio of the m-chloroperoxybenzoic acid, dichloromethane, and modified itaconic acid dispersion described in B5 is 103-134:400-500:223-280;

[0035] The mass ratio of itaconic acid-based epoxy resin to curing agent in B6 is 28-36:5-6;

[0036] The gradient curing described in B6 is as follows: first, pre-curing at 60-70℃ for 1-2 hours, then pre-curing at 80-100℃ for 2-3 hours, and then curing at 135-140℃ for 2-3 hours.

[0037] The beneficial effects of this invention are:

[0038] This invention provides a wear-resistant and pressure-resistant coated bamboo plywood and its preparation method. The invention effectively improves the moisture resistance, mildew resistance and flame retardancy of bamboo plywood through the following methods.

[0039] (1) In the preparation process of the modified bamboo strips of the present invention, the pretreatment not only dissolves the wax, hemicellulose and some lignin on the surface of the bamboo strips, increasing the surface roughness, but also destroys the hydrogen bonds between the bamboo strip fibers, making the fiber structure looser; this increases the specific surface area of ​​the bamboo strips and improves the bonding ability. Aminoation treatment will form covalent bonds with the hydroxyl groups on the surface of the bamboo strips, exposing the amino groups on the surface of the bamboo strips, significantly improving the interfacial bonding strength; silane molecules will also self-assemble to form a thin layer, reducing the surface energy, and the hydrophobicity of the silane coating will reduce water penetration, inhibiting the humid environment required for mold growth; amino groups can also inhibit some molds; the silane coating can also increase hardness, improve surface smoothness, and improve wear resistance. Flame retardant impregnation will penetrate diammonium hydrogen phosphate into the pores of the bamboo strips, forming a uniformly distributed flame retardant system, increasing the ignition temperature of the bamboo strips and reducing the heat release rate; phosphate filling the pores can also enhance the bonding force between fibers and improve the overall compressive stiffness; the phosphate environment can inhibit the activity of microbial enzymes. Mineralization creates a silica gel network that fills the micropores and surface of bamboo strips. After curing, the silica gel forms a high-hardness, wear-resistant barrier, enhancing the structural support of the bamboo strips and significantly improving their wear resistance, moisture resistance, and compressive strength. The introduction of a silane composite coating modifies the bamboo strip surface, forming a high-hardness, high-density, and highly hydrophobic wear-resistant layer. The methyl groups on the surface of this wear-resistant layer increase the water contact angle, making it difficult for moisture to penetrate, significantly improving moisture resistance and thus enhancing mold resistance. The hydroxyl groups on the coating surface can form chemical bonds with the epoxy resin of the coated paper, strengthening the interlayer bond between the bamboo mat and the coated paper, significantly improving the bonding strength of the coated bamboo plywood. As a rigid "shell," the silane composite coating also constrains the deformation of the internal fibers of the bamboo strips. Especially after hot pressing, the coating works synergistically with the bamboo fibers to bear the load, effectively improving overall compressive strength.

[0040] (2) The curing agent of this invention is generated by the reaction of phytic acid and imidazole. The phosphate groups in phytic acid can form a phosphate ester flame retardant layer at high temperature, promote the carbonization of the material surface, and isolate oxygen and heat transfer. The nitrogen-containing structure of imidazole releases inert gas during combustion, dilutes the oxygen concentration, and participates in the formation of an intumescent char layer, inhibiting the spread of flame. The synergistic effect of the two can significantly reduce the flammability of the material and improve its fire resistance. The curing agent can promote the formation of a high cross-linking density network of itaconic acid-based epoxy resin, reduce the gaps between molecular chains, and reduce the water penetration path. The density of the cured coating is improved and the water absorption rate is reduced, which can enhance the waterproof and moisture-proof ability of the wood surface. Phytic acid inhibits mold metabolism by chelating the metal ions necessary for the growth of microorganisms. Imidazole and its derivatives have broad-spectrum antibacterial activity and can directly destroy the cell membrane of mold or inhibit enzyme activity. The synergistic effect of the two can effectively inhibit mold growth. After the itaconic acid-based epoxy resin is cured, the imidazole structure will also be embedded in the epoxy resin network of the coated paper, making the anti-mold property of the coated bamboo plywood lasting and stable. Phytic acid's polyacid structure undergoes a polyacid cross-linking reaction with the epoxy groups of itaconic acid-based epoxy resin to form a three-dimensional network structure, increasing the cross-linking density. Imidazole can accelerate the reaction process, making the system more completely cured and significantly improving the surface hardness and wear resistance of the coated bamboo plywood.

[0041] (3) The itaconic acid-based epoxy resin of this invention forms a "phosphorus-carbon" synergistic flame retardant system with the phosphorus element introduced during the bamboo modification process. The three-dimensional network structure formed by the curing of epoxy resin enhances the stability of the dense carbon layer formed by the phosphorus element, reduces the release of combustible gases, and thus improves the overall flame retardant level. The cured product of itaconic acid-based epoxy resin also has a high thermal decomposition temperature, which can slow down the degradation rate of the material at high temperatures. This complements the flame retardant pretreatment of bamboo, making the bamboo plywood less likely to burn quickly or melt and drip when exposed to fire, thereby further improving the fire resistance of the coated bamboo plywood. The non-porous dense coated paper formed after the epoxy resin is cured can block the penetration of moisture, oxygen and nutrients required by microorganisms, destroy the survival environment of mold, and reduce the probability of mold growth. The alkyl chains introduced during the modification of itaconic acid with allyl bromide increase the hydrophobicity of the molecular chain. In the epoxy resin structure after epoxidation, the number of hydrophilic groups such as hydroxyl groups decreases, and the ether bonds and carbon chain structures formed after curing have low hygroscopicity, reducing the water absorption rate of the coated paper. The coated paper also adheres tightly to the bamboo surface, filling the bamboo pores and forming a waterproof layer, preventing moisture from penetrating into the bamboo plywood, especially reducing the risk of delamination caused by water penetration at the interlayer interface, thus improving water resistance and mildew resistance. Cured epoxy resin has high hardness and excellent abrasion resistance, allowing it to directly withstand mechanical wear as a surface coating. The itaconic acid-based epoxy resin, due to the introduction of double bonds and cyclic structures, has a higher cross-linking density after curing, resulting in a stronger scratch-resistant film. The epoxy groups in the epoxy resin can chemically react with the hydroxyl groups on the bamboo surface to form covalent bonds, and the epoxy groups further react with amino groups, enhancing the interfacial bonding between the film and the bamboo, preventing the coating from peeling off during wear resistance. The rigid network formed by the cured itaconic acid-based epoxy resin can uniformly transmit compressive stress, preventing deformation or cracking caused by stress concentration between bamboo mat layers. Its high modulus properties also enhance the overall compressive strength of the bamboo plywood. The coated paper, acting as an adhesive between the bamboo mat layers, bonds the bamboo mat tightly into a whole after hot pressing and curing, reducing interlayer slippage and improving compressive strength. The epoxy groups undergo ring-opening addition reactions with the hydroxyl groups on the bamboo surface, forming a strong chemical bond. The imidazole curing agent, acting as a catalyst, promotes the reaction between the epoxy groups and amino and hydroxyl groups, increasing the interfacial crosslinking density and further improving the bonding strength.

[0042] Therefore, the wear-resistant and pressure-resistant coated bamboo plywood prepared by this invention has excellent wear resistance, pressure resistance, bonding strength, moisture resistance, mildew resistance and flame retardancy, as well as a wider range of application prospects. Detailed Implementation

[0043] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] Example 1: A method for preparing a wear-resistant and pressure-resistant coated bamboo plywood is as follows:

[0045] S1: Dissolve 10g sodium hydroxide and 8g sodium sulfite in 600mL of deionized water, then immerse bamboo strips with a thickness of 0.1cm and stir at 150r / min for 3h at 80℃. After filtration, rinse the bamboo strips with deionized water 8 times for 3min each time, and then dry at 65℃ for 10h to obtain pretreated bamboo strips.

[0046] S2: Add 10mL of deionized water and 2g of silane coupling agent KH-550 to 90g of anhydrous ethanol and stir for 30min. Adjust the pH to 4.5 and then immerse the pretreated bamboo strips in the solution and shake at 70 times / min for 2h at 45℃. Then take out the bamboo strips and ultrasonically clean them three times for 3min each time with deionized water. Finally, vacuum dry them at 55℃ for 10h to obtain aminated bamboo strips.

[0047] S3: Dissolve 22.8g of diammonium hydrogen phosphate in 400mL of deionized water and perform ultrasonic dispersion at 250W and 35kHz for 15min. Then, immerse the aminated bamboo strips in the solution and degas them under vacuum of -0.09MPa for 5min. Repeat the cycle 5 times and then immerse the bamboo strips under vacuum of -0.09MPa for 10h. After removing the bamboo strips, hang them vertically for 30min and then dry them at 45℃ for 2h to obtain flame-retardant bamboo strips.

[0048] S4: Immerse the flame-retardant bamboo strips in a 5% sodium silicate aqueous solution and soak them under a vacuum of -0.09MPa for 5 minutes. Then degas the solution and repeat the process 5 times. After soaking the bamboo strips under a vacuum of -0.09MPa for 4 hours, remove the bamboo strips and hang them vertically for 30 minutes. Then dry them at 45℃ for 2 hours to obtain mineralized bamboo strips.

[0049] S5: Add 50g tetraethyl orthosilicate, 20g trimethylethoxysilane, and 20g methanol to 100g deionized water and stir at 300r / min for 1h. Then adjust the pH to 11 with 25% ammonia solution, and then add 180g / m 2 The coating amount was evenly spin-coated onto the surface of the mineralized bamboo strips. Finally, it was pre-cured at 60℃ for 2 hours and then cured at 130℃ and 0.2MPa pressure for 2 hours to obtain the modified bamboo strips.

[0050] S6: Dissolve 10g of phytic acid in 40mL of deionized water to obtain a phytic acid dispersion;

[0051] S7: Dissolve 7.5g imidazole in 40mL of deionized water, then add 50g phytic acid dispersion and stir for 8h. Then, rotary evaporate under reduced pressure at 55℃ for 70min to obtain the curing agent.

[0052] S8: Add 25g itaconic acid and 58.5g potassium carbonate to 50g N,N-dimethylformamide and stir for 30min. Then add 27g allyl bromide and react at 55℃ for 10h. Then add 300mL deionized water at 5℃ and stir for 20min. Then extract with dichloromethane 3 times and wash the extract with deionized water 5 times. Then add 5g anhydrous magnesium sulfate to dry the organic phase. After stirring for 10min, filter. The filtrate is first rotary evaporated at 38℃ for 1h and then vacuum dried at 55℃ for 20h to obtain modified itaconic acid.

[0053] S9: Dissolve 23g of modified itaconic acid in 200g of dichloromethane to obtain a modified itaconic acid dispersion;

[0054] S10: Dissolve 103g of m-chloroperoxybenzoic acid in 400g of dichloromethane, then add 223g of modified itaconic acid dispersion dropwise and react at 30℃ for 90h. After filtration, wash the solution three times with 5% sodium thiosulfate, then wash three times each with saturated sodium bicarbonate solution and saturated sodium chloride solution. Then add anhydrous magnesium sulfate to dry the organic phase, stir for 10min and filter. The filtrate is first rotary evaporated under reduced pressure at 35℃ for 2h, and then vacuum dried at 55℃ for 4h to obtain itaconic acid-based epoxy resin.

[0055] S11: Add 5g of curing agent to 28g of itaconic acid-based epoxy resin and stir for 40min. Then degas for 20min under a gauge pressure of -0.095MPa, and then apply 180g / m 2 The coating amount is evenly coated on the surface of the film-forming plate. Finally, it is pre-cured at 60℃ for 1 hour, then pre-cured at 80℃ for 2 hours, and then cured at 135℃ for 2 hours. After demolding, the coated paper is obtained.

[0056] S12: Modified bamboo strips are woven into bamboo mats. Then, one bamboo mat is stacked on one sheet of coated paper, and another sheet of coated paper is stacked on the bamboo mat. This process is repeated, with two bamboo mats and two sheets of coated paper stacked on top of each other. The mats are then hot-pressed at 120°C and 2MPa for 10 minutes, followed by pressure at 50°C for 10 minutes. After cooling to room temperature and normal pressure, the mats are sanded and the edges are trimmed to obtain wear-resistant and pressure-resistant coated bamboo plywood.

[0057] Example 2: A method for preparing a wear-resistant and pressure-resistant coated bamboo plywood is as follows:

[0058] S1: Dissolve 15g sodium hydroxide and 12g sodium sulfite in 650mL of deionized water, then immerse the bamboo strips with a thickness of 0.3cm and stir at 200r / min for 5h at 85℃. After filtration, rinse the bamboo strips with deionized water 9 times for 4min each time, and then dry at 68℃ for 13h to obtain pretreated bamboo strips.

[0059] S2: Add 12.5 mL of deionized water and 2.5 g of silane coupling agent KH-550 to 112.5 g of anhydrous ethanol and stir for 40 min. Adjust the pH to 4.8 and then immerse the pretreated bamboo strips in the solution and shake at 80 times / min at 48℃ for 2.5 h. Then take out the bamboo strips and ultrasonically clean them with deionized water for 4 min each time. Finally, vacuum dry them at 58℃ for 13 h to obtain aminated bamboo strips.

[0060] S3: Dissolve 28.5g of diammonium hydrogen phosphate in 500mL of deionized water and perform ultrasonic dispersion at 280W and 38kHz for 20min. Then, immerse the aminated bamboo strips in the solution and soak them under vacuum of -0.09MPa for 8min. After degassing, repeat the cycle 6 times and soak them under vacuum of -0.09MPa for 13h. After removing the bamboo strips, hang them vertically for 45min and then dry them at 48℃ for 3h to obtain flame-retardant bamboo strips.

[0061] S4: Immerse the flame-retardant bamboo strips in an 8% sodium silicate aqueous solution and soak them under a vacuum of -0.09MPa for 8 minutes. Then degas the solution and repeat the process 6 times. After soaking the bamboo strips under a vacuum of -0.09MPa for 8 hours, remove the bamboo strips and hang them vertically for 45 minutes. Then dry them at 48℃ for 3 hours to obtain mineralized bamboo strips.

[0062] S5: Add 55g tetraethyl orthosilicate, 22g trimethylethoxysilane, and 22g methanol to 110g deionized water and stir at 350r / min for 1.5h. Then adjust the pH to 11.5 with 27% ammonia solution, and then add 200g / m 2 The coating amount was evenly spin-coated onto the surface of the mineralized bamboo strips. Finally, it was pre-cured at 70℃ for 3 hours and then cured at 135℃ and 0.4MPa pressure for 2.5 hours to obtain the modified bamboo strips.

[0063] S6: Dissolve 11g of phytic acid in 45mL of deionized water to obtain a phytic acid dispersion;

[0064] S7: Dissolve 8.3g imidazole in 45mL of deionized water, then add 56g phytic acid dispersion and stir for 9h. Then, rotary evaporate under reduced pressure at 60℃ for 80min to obtain the curing agent.

[0065] S8: Add 27.5g itaconic acid and 64.5g potassium carbonate to 55g N,N-dimethylformamide and stir for 35min. Then add 29.5g allyl bromide and react at 60℃ for 13h. Then add 330mL deionized water at 10℃ and stir for 30min. Then extract with dichloromethane 4 times and wash the extract with deionized water 6 times. Then add 7.5g anhydrous magnesium sulfate to dry the organic phase. After stirring for 20min, filter. The filtrate is first rotary evaporated at 40℃ for 1.5h and then vacuum dried at 58℃ for 23h to obtain modified itaconic acid.

[0066] S9: Dissolve 26.5g of modified itaconic acid in 225g of dichloromethane to obtain a modified itaconic acid dispersion;

[0067] S10: Dissolve 118.5g of m-chloroperoxybenzoic acid in 450g of dichloromethane, then add 251.5g of modified itaconic acid dispersion dropwise and react at 35℃ for 95h. After filtration, wash the solution four times with 5% sodium thiosulfate, then wash four times each with saturated sodium bicarbonate solution and saturated sodium chloride solution. Then add anhydrous magnesium sulfate to dry the organic phase, stir for 20min and filter. The filtrate is first rotary evaporated under reduced pressure at 38℃ for 2.5h, and then vacuum dried at 58℃ for 6h to obtain itaconic acid-based epoxy resin.

[0068] S11: Add 5.5g of curing agent to 32g of itaconic acid-based epoxy resin and stir for 50min. Then degas for 25min under a gauge pressure of -0.095MPa, and then apply 200g / m³ of curing agent. 2 The coating amount is evenly coated on the surface of the film-forming plate. Finally, it is pre-cured at 65℃ for 1.5h, then pre-cured at 90℃ for 2.5h, and then cured at 138℃ for 2.5h. After demolding, the coated paper is obtained.

[0069] S12: Modified bamboo strips are woven into bamboo mats. Then, one bamboo mat is stacked on one sheet of coated paper, and another sheet of coated paper is stacked on top of the bamboo mat. This process is repeated, with three bamboo mats and three sheets of coated paper stacked on top of each other. The mats are then hot-pressed at 125°C and 2.5MPa for 15 minutes, followed by pressure holding at 55°C for 15 minutes. After cooling to room temperature and normal pressure, the mats are sanded and the edges are trimmed to obtain wear-resistant and pressure-resistant coated bamboo plywood.

[0070] Example 3: A method for preparing a wear-resistant and pressure-resistant coated bamboo plywood is as follows:

[0071] S1: Dissolve 20g sodium hydroxide and 16g sodium sulfite in 700mL of deionized water, then immerse bamboo strips with a thickness of 0.5cm and stir at 300r / min for 6h at 90℃. After filtration, rinse the bamboo strips with deionized water 10 times for 5min each time, and then dry at 70℃ for 15h to obtain pretreated bamboo strips.

[0072] S2: Add 15mL of deionized water and 3g of silane coupling agent KH-550 to 135g of anhydrous ethanol and stir for 50min. Adjust the pH to 5.0 and then immerse the pretreated bamboo strips in the solution and shake at 90 times / min for 3h at 50℃. Then take out the bamboo strips and ultrasonically clean them 5 times for 5min each time with deionized water. Finally, vacuum dry them at 60℃ for 15h to obtain aminated bamboo strips.

[0073] S3: Dissolve 34.2g of diammonium hydrogen phosphate in 600mL of deionized water and perform ultrasonic dispersion at 300W and 40kHz for 30min. Then, immerse the aminated bamboo chips in the solution and soak them under vacuum of -0.09MPa for 10min. After degassing, repeat the cycle 7 times and soak them under vacuum of -0.09MPa for 15h. After removing the bamboo chips, hang them vertically for 60min and then dry them at 50℃ for 4h to obtain flame-retardant bamboo chips.

[0074] S4: Immerse the flame-retardant bamboo strips in a 10% sodium silicate aqueous solution and soak them under a vacuum of -0.09MPa for 10 minutes. Then degas the solution and repeat the process 7 times. After soaking the bamboo strips under a vacuum of -0.09MPa for 12 hours, remove the bamboo strips and hang them vertically for 60 minutes. Then dry them at 50℃ for 4 hours to obtain mineralized bamboo strips.

[0075] S5: Add 60g tetraethyl orthosilicate, 24g trimethylethoxysilane, and 24g methanol to 120g deionized water and stir at 400r / min for 2h. Then adjust the pH to 12 with 28% ammonia solution, and then add 220g / m 2 The coating amount was evenly spin-coated onto the surface of the mineralized bamboo strips. Finally, it was pre-cured at 80℃ for 4 hours and then cured at 140℃ and 0.5MPa pressure for 3 hours to obtain the modified bamboo strips.

[0076] S6: Dissolve 12g of phytic acid in 50mL of deionized water to obtain a phytic acid dispersion;

[0077] S7: Dissolve 9g imidazole in 50mL deionized water, then add 62g phytic acid dispersion and stir for 10h, then rotary evaporate under reduced pressure at 65℃ for 90min to obtain curing agent;

[0078] S8: Add 30g itaconic acid and 70.5g potassium carbonate to 60g N,N-dimethylformamide and stir for 40min. Then add 32g allyl bromide and react at 65℃ for 15h. Then add 350mL deionized water at 15℃ and stir for 40min. Then extract with dichloromethane 5 times and wash the extract with deionized water 7 times. Then add 10g anhydrous magnesium sulfate to dry the organic phase. After stirring for 30min, filter. The filtrate is first rotary evaporated at 42℃ for 2h and then vacuum dried at 60℃ for 25h to obtain modified itaconic acid.

[0079] S9: Dissolve 30g of modified itaconic acid in 250g of dichloromethane to obtain a modified itaconic acid dispersion;

[0080] S10: Dissolve 134g of m-chloroperoxybenzoic acid in 500g of dichloromethane, then add 280g of modified itaconic acid dispersion dropwise and react at 40℃ for 100h. After filtration, wash the solution 5 times with 5% sodium thiosulfate, then wash 5 times each with saturated sodium bicarbonate solution and saturated sodium chloride solution. Then add anhydrous magnesium sulfate to dry the organic phase, stir for 30min and filter. The filtrate is first rotary evaporated under reduced pressure at 40℃ for 3h, and then vacuum dried at 60℃ for 8h to obtain itaconic acid-based epoxy resin.

[0081] S11: Add 6g of curing agent to 36g of itaconic acid-based epoxy resin and stir for 60min. Then degas for 30min under a gauge pressure of -0.095MPa, and then apply 220g / m³ of curing agent. 2 The coating amount is evenly coated on the surface of the film-forming plate. Finally, it is pre-cured at 70℃ for 2 hours, then pre-cured at 100℃ for 3 hours, and then cured at 140℃ for 3 hours. After demolding, the coated paper is obtained.

[0082] S12: Modified bamboo strips are woven into bamboo mats. Then, one bamboo mat is stacked on one sheet of coated paper, and another sheet of coated paper is stacked on the bamboo mat. This process is repeated, with four bamboo mats and four sheets of coated paper stacked in sequence. The mats are then hot-pressed at 130℃ and 3MPa for 20 minutes, and then kept under pressure at 60℃ for 20 minutes. After cooling to room temperature and normal pressure, the mats are sanded and the edges are trimmed to obtain wear-resistant and pressure-resistant coated bamboo plywood.

[0083] Comparative Example 1:

[0084] Compared with Example 1, this comparative example only replaces the "pretreated bamboo strips" added in the preparation process of S2 with "bamboo strips with a thickness of 0.1cm". All other steps and parameters are the same, and will not be repeated in this comparative example. Finally, wear-resistant and pressure-resistant coated bamboo plywood is obtained.

[0085] Comparative Example 2:

[0086] Compared with Example 1, this comparative example only replaces the "flame-retardant bamboo strips" added in the preparation process of S4 with the "pretreated bamboo strips" prepared in S1. All other steps and parameters are the same, and will not be repeated in this comparative example. Finally, wear-resistant and pressure-resistant coated bamboo plywood is obtained.

[0087] Comparative Example 3:

[0088] Compared with Example 1, this comparative example only replaces the "mineralized bamboo chips" added in the preparation process of S5 with the "pretreated bamboo chips" prepared in S1. All other steps and parameters are the same, and will not be repeated in this comparative example. Finally, wear-resistant and pressure-resistant coated bamboo plywood is obtained.

[0089] Comparative Example 4:

[0090] Compared with Example 1, this comparative example only replaces the "modified bamboo strips" added in the preparation process of S12 with the "pretreated bamboo strips" prepared in S1. All other steps and parameters are the same, and will not be repeated in this comparative example. Finally, wear-resistant and pressure-resistant coated bamboo plywood is obtained.

[0091] Comparative Example 5:

[0092] Compared with Example 1, this comparative example only replaces the "curing agent" added in the preparation process of S11 with "phytic acid". All other steps and parameters are the same, and will not be repeated in this comparative example. Finally, wear-resistant and pressure-resistant coated bamboo plywood is obtained.

[0093] Comparative Example 6:

[0094] Compared with Example 1, this comparative example only replaces the "curing agent" added in the preparation process of S11 with "imidazolium". All other steps and parameters are the same, and will not be repeated in this comparative example. Finally, wear-resistant and pressure-resistant coated bamboo plywood is obtained.

[0095] Comparative Example 7:

[0096] Compared with Example 1, this comparative example only changes the preparation process of S12, where "modified bamboo strips are woven into bamboo mats, then one bamboo mat is stacked on one sheet of coated paper, then another sheet of coated paper is stacked on the bamboo mat, and so on, with two bamboo mats and two sheets of coated paper stacked in sequence. Then, the mats are hot-pressed at 120°C and 2MPa for 10 minutes, then pressed at 50°C for 10 minutes, and after cooling to room temperature, they are sanded and the edges are trimmed to obtain wear-resistant and pressure-resistant coated bamboo plywood." The remaining steps and parameters are the same, and will not be repeated in this comparative example. The final product is wear-resistant and pressure-resistant coated bamboo plywood.

[0097] Performance testing:

[0098] Abrasion resistance testing:

[0099] Referring to the abrasion test method (Method 1) in GB / T 17657-2013 "Test Methods for Physical and Chemical Properties of Wood-based Panels and Decorative Wood-based Panels", the number of revolutions when the wear-resistant and pressure-resistant coated bamboo plywood prepared in Examples 1-3 and Comparative Examples 1-7 was ground to the surface of bamboo strips under 5N pressure was determined using P180 grit abrasive cloth (during which the abrasive cloth was changed every 500 revolutions and the wear condition was checked every 25 revolutions) to reflect the wear resistance (revolutions) of the wear-resistant and pressure-resistant coated bamboo plywood. The test results are shown in Table 1.

[0100] Determination of compressive strength:

[0101] Referring to the test method for compressive strength along the grain of wood-based panels in GB / T 17657-2013 "Test Methods for Physical and Chemical Properties of Wood-based Panels and Decorative Wood-based Panels", the compressive strength (MPa) of the wear-resistant and compressive-resistant coated bamboo plywood prepared in Examples 1-3 and Comparative Examples 1-7 was determined. The test results are shown in Table 1.

[0102] Determination of adhesive strength:

[0103] Referring to the Surface Bonding Strength Test Method in GB / T 17657-2013 "Test Methods for Physical and Chemical Properties of Wood-based Panels and Decorative Wood-based Panels", the bonding strength (MPa) of the wear-resistant and compression-resistant coated bamboo plywood prepared in Examples 1-3 and Comparative Examples 1-7 was determined. The test results are shown in Table 1.

[0104] Moisture resistance test:

[0105] Referring to the surface bonding strength determination method in 4.1 of GB / T 17657-2013 "Test Methods for Physical and Chemical Properties of Wood-based Panels and Decorative Wood-based Panels", the bonding strength retention rate (%) of the wear-resistant and pressure-resistant coated bamboo plywood prepared in Examples 1-3 and Comparative Examples 1-7 after being placed in an environment of 25°C and 95% relative humidity for 28 days was determined to reflect the moisture resistance of the wear-resistant and pressure-resistant coated bamboo plywood of the present invention. The test results are shown in Table 1.

[0106] Flame retardancy testing:

[0107] Referring to GB / T 2408-2021 "Determination of flammability of plastics by horizontal and vertical burning methods", the flame retardant rating (grade) of the wear-resistant and pressure-resistant coated bamboo plywood prepared in Examples 1-3 and Comparative Examples 1-7 of this invention was determined by vertical burning test (V method). The test results are shown in Table 1.

[0108] Determination of anti-mildew properties:

[0109] Referring to GB / T 35469-2017 "Test Method for Mildew Resistance of Wood-Plastic Composite Materials in Buildings" standard, take 10 mL of a solution with a concentration of 5×10 6 A suspension of *Aspergillus niger* CGMCC 3.5487 spores / mL was uniformly coated onto the surface of a 50mm × 50mm wear-resistant and pressure-resistant coated bamboo plywood. After incubation at 37℃ and 95% relative humidity for 28 days, the percentage of mold-covered area was measured to reflect the anti-mold ability; the smaller the percentage of mold-covered area, the stronger the anti-mold ability. The anti-mold ability (%) of the wear-resistant and pressure-resistant coated bamboo plywood prepared using Examples 1-3 and Comparative Examples 1-7 of this invention was determined according to this method, and the results are shown in Table 1.

[0110] Table 1: Performance test results of Examples 1-3 and Comparative Examples 1-7

[0111]

[0112] Data Analysis:

[0113] As can be seen from Table 1, the wear-resistant and pressure-resistant coated bamboo plywood prepared in the embodiments of the present invention has excellent wear resistance, pressure resistance, bonding strength, moisture resistance, mildew resistance and flame retardancy.

[0114] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A method for preparing wear-resistant and pressure-resistant coated bamboo plywood, characterized in that, Includes the following steps: Modified bamboo strips are woven into bamboo mats. Then, one bamboo mat is placed on one sheet of coated paper, and another sheet of coated paper is placed on top of the bamboo mat. This process is repeated, with 2-4 bamboo mats and 4 sheets of coated paper placed on top of each other. The mats are then hot-pressed at 120-130℃ and 2-3MPa for 10-20 minutes, followed by pressure holding at 50-60℃ for 10-20 minutes. After depressurization and cooling, the mats are sanded and the edges are trimmed to obtain wear-resistant and pressure-resistant coated bamboo plywood. The coated paper is prepared from imidazole, phytic acid, and itaconic acid-based epoxy resin; The modified bamboo strips are prepared as follows: A1: Dissolve sodium hydroxide and sodium sulfite in deionized water, then soak bamboo strips in the solution and stir at 80-90℃ for 3-6 hours. After filtration, rinse the bamboo strips and dry them to obtain pretreated bamboo strips. A2: Add deionized water and silane coupling agent KH-550 to anhydrous ethanol and stir for 30-50 minutes. Adjust the pH to 4.5-5.0, then immerse the pretreated bamboo strips and shake at 45-50℃ for 2-3 hours. After removing the bamboo strips, clean them with ultrasound and dry them under vacuum to obtain aminated bamboo strips. A3: Dissolve diammonium hydrogen phosphate in deionized water and ultrasonically disperse for 15-30 minutes. Then, immerse it in aminated bamboo strips and vacuum impregnate it. After removing the bamboo strips, dry them to obtain flame-retardant bamboo strips. A4: Immerse flame-retardant bamboo strips in an aqueous sodium silicate solution and perform vacuum impregnation. Remove the bamboo strips and dry them to obtain mineralized bamboo strips. A5: Add tetraethyl orthosilicate, trimethylethoxysilane, and methanol to deionized water and stir for 1-2 hours. Then adjust the pH to 11-12 and spin-coat it onto the surface of mineralized bamboo strips. After curing, the modified bamboo strips are obtained. The method for preparing the coated paper is as follows: B1: Dissolve phytic acid in deionized water to obtain a phytic acid dispersion; B2: Imidazole is dissolved in deionized water and then added dropwise to phytic acid dispersion and stirred for 8-10 hours. The curing agent is obtained by rotary evaporation under reduced pressure. B3: Add itaconic acid and potassium carbonate to N,N-dimethylformamide and stir for 30-40 min. Then, add allyl bromide dropwise and react at 55-65℃ for 10-15 h. Then, add deionized water and stir for 20-40 min. Extract with dichloromethane and wash the extract with deionized water. Finally, add anhydrous magnesium sulfate to the organic phase, stir for 10-30 min, filter, and evaporate the filtrate by rotary evaporation and vacuum drying to obtain modified itaconic acid. B4: Dissolve the modified itaconic acid in dichloromethane to obtain a modified itaconic acid dispersion; B5: Dissolve m-chloroperoxybenzoic acid in dichloromethane, then add it dropwise to the modified itaconic acid dispersion and react at 30-40℃ for 90-100h. After filtration, wash the filtrate, then add anhydrous magnesium sulfate to the organic phase, stir for 10-30min and filter. First, rotary evaporate the filtrate under reduced pressure at 35-40℃ for 2-3h, then vacuum dry at 55-60℃ for 4-8h to obtain itaconic acid-based epoxy resin. B6: Add curing agent to itaconic acid-based epoxy resin and stir for 40-60 minutes. After degassing, spin coat it onto the surface of the film-forming plate. After gradient curing, demold to obtain the coated paper.

2. The method for preparing wear-resistant and pressure-resistant coated bamboo plywood according to claim 1, characterized in that, The mass ratio of deionized water, sodium hydroxide, and sodium sulfite in A1 is 600-700:10-20:8-16; The mass ratio of anhydrous ethanol, deionized water, and silane coupling agent KH-550 in A2 is 90-135:10-15:2-3.

3. The method for preparing wear-resistant and pressure-resistant coated bamboo plywood according to claim 1, characterized in that, The mass ratio of diammonium hydrogen phosphate to deionized water in A3 is 22.8-34.2:400-600; The vacuum impregnation described in A3 is as follows: after impregnation for 5-10 minutes under a vacuum of -0.09 MPa, degas the mixture, repeat the cycle 5-7 times, and then impregnate for 10-15 hours under a vacuum of -0.09 MPa.

4. The method for preparing wear-resistant and pressure-resistant coated bamboo plywood according to claim 1, characterized in that, The sodium silicate aqueous solution described in A4 has a mass fraction of 5%-10%; The vacuum impregnation described in A4 is as follows: after impregnation for 5-10 minutes under a vacuum of -0.09 MPa, degas the mixture, repeat the cycle 5-7 times, and then impregnate for 4-12 hours under a vacuum of -0.09 MPa.

5. The method for preparing wear-resistant and pressure-resistant coated bamboo plywood according to claim 1, characterized in that, The mass ratio of deionized water, tetraethyl orthosilicate, trimethylethoxysilane, and methanol in A5 is 100-120:50-60:20-24:20-24; The curing process described in A5 is as follows: first, pre-curing at 60-80℃ for 2-4 hours, and then curing at 130-140℃ and 0.2-0.5MPa pressure for 2-3 hours.

6. The method for preparing wear-resistant and pressure-resistant coated bamboo plywood according to claim 1, characterized in that, The mass ratio of phytic acid to deionized water in B1 is 10-12:40-50; The mass ratio of imidazole, deionized water, and phytic acid dispersion in B2 is 7.5-9:40-50:50-62.

7. The method for preparing wear-resistant and pressure-resistant coated bamboo plywood according to claim 1, characterized in that, The mass ratio of N,N-dimethylformamide, itaconic acid, potassium carbonate, allyl bromide, deionized water, and anhydrous magnesium sulfate described in B3 is 50-60:25-30:58.5-70.5:27-32:300-350:5-10; The mass ratio of modified itaconic acid to dichloromethane in B4 is 23-30:200-250; The mass ratio of the m-chloroperoxybenzoic acid, dichloromethane, and modified itaconic acid dispersion described in B5 is 103-134:400-500:223-280; The mass ratio of itaconic acid-based epoxy resin to curing agent in B6 is 28-36:5-6; The gradient curing described in B6 is as follows: first, pre-curing at 60-70℃ for 1-2 hours, then pre-curing at 80-100℃ for 2-3 hours, and then curing at 135-140℃ for 2-3 hours.

8. A wear-resistant and pressure-resistant coated bamboo plywood, characterized in that, It is prepared by the preparation method described in any one of claims 1-7.

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