Ecological density board and preparation method thereof

Abstract

The invention discloses an ecological density board and a preparation method thereof, and belongs to the technical field of artificial boards. The environment-friendly coating is coated on the surface of the density board, so that the durability and flame retardance of the ecological board are improved, the environment-friendly coating can continuously release negative ions, remove harmful pollutants such as formaldehyde released by wood fibers and effectively improve the air quality, and the environment-friendly coating is compact in film formation, high in mechanical strength and good in flame retardance. The overall performance and the service life of the ecological density board can be effectively improved. Meanwhile, functional components such as modified titanium dioxide and carbon nanotubes are introduced, so that the coating has excellent aging resistance and flame retardance, in addition, an environment-friendly solvent is adopted in the system, VOC emission is reduced, and the green and environment-friendly concept is met.

Description

Technical Field

[0001] The present invention relates to the technical field of artificial boards, and in particular to an ecological density board and a preparation method thereof. Background Art

[0002] Ecological density board (MDF), an important man-made board material, is widely used in industries such as home furnishing, construction, and electronics. Made primarily from renewable resources such as wood and plant fibers, it undergoes mechanical separation, chemical treatment, the addition of environmentally friendly adhesives and waterproofing agents, and is then pressed under high temperature and high pressure. It boasts uniform structure, excellent physical properties, and high dimensional stability. Compared to natural wood, MDF overcomes the shortcomings of decay, insect damage, and significant expansion and contraction. Its surface is also smooth and easily processed and decorated.

[0003] With the widespread adoption of green environmental protection concepts and the continued improvement of downstream board performance, traditional density fiberboard (MDF) has exposed shortcomings in fire resistance, aging resistance, and surface properties. For example, eco-friendly density fiberboard is often used as drilling pads for printed circuit boards in the electronics industry. This operating environment requires high-temperature, high-pressure heat treatment and prolonged electrical work, placing higher demands on the board's inherent heat resistance and flame retardancy. If the board's heat resistance and flame retardancy are insufficient, it is prone to combustion when localized temperatures rise, posing a serious safety hazard.

[0004] Chinese patent document CN110341023A discloses a flame-retardant lightweight density board and its preparation method. The board is made by hot pressing plant fibers, a composite flame retardant, and an adhesive. The composite flame retardant is a mixture of urea phosphate, ammonium dihydrogen phosphate, and colemanite in a mass ratio of 2:2:1. The flame-retardant lightweight density board produced by this invention offers excellent flame retardancy and is lightweight. The composite flame retardant, urea phosphate, ammonium dihydrogen phosphate, and colemanite, synergistically enhance the flame retardancy significantly better than a single agent alone. It is used in building materials for the home renovation industry and offers a high fire rating. However, the flame retardant used in this invention suffers from poor compatibility with the substrate. Furthermore, UV aging can cause yellowing, chalking, and damage to the board surface, impacting durability and service life. Summary of the Invention

[0005] The main purpose of the present invention is to propose an ecological density board and a preparation method thereof. By coating an environmentally friendly coating on the surface of the density board, the environmentally friendly coating can continuously release negative ions, remove harmful pollutants such as formaldehyde released by wood fibers, effectively improve air quality, and also have specific anti-aging and flame retardant properties, which can improve the durability and flame retardant properties of the ecological density board.

[0006] To achieve the above-mentioned purpose, the present invention proposes an ecological density board, comprising a density board and an environmentally friendly paint coated on the surface of the density board; the environmentally friendly paint comprises the following components by weight: 50-70 parts of water-based acrylic resin, 1-3 parts of negative ion powder, 5-15 parts of modified carbon nanotubes, 0.01-0.2 parts of dispersant, 5-15 parts of water, 0.1-0.5 parts of defoaming agent, 0.01-0.2 parts of thickener, and 0.1-1 parts of propylene glycol methyl ether acetate.

[0007] Preferably, the preparation method of the modified carbon nanotubes is as follows: The carbon nanotubes are dispersed in concentrated nitric acid, heated and stirred by ultrasonic treatment, cooled to room temperature, filtered, the solids are collected, washed with water until neutral, and dried to obtain pretreated carbon nanotubes; the pretreated carbon nanotubes are mixed evenly with an ethanol aqueous solution, KH550 is added, heated to react, the obtained solid product is added to N,N-dimethylformamide, pterin-6-carboxylic acid, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, and N-hydroxysuccinimide are added, the temperature is increased to react, filtered, the solids are collected, washed and dried, and then dispersed in chloroform, triethylamine is added, the mixture is stirred evenly, diphenylphosphinoyl chloride is added dropwise, stirred for reaction, washed with water after the reaction is completed, filtered, the solids are collected, washed and dried to obtain modified carbon nanotubes.

[0008] Preferably, the mass ratio of the pretreated carbon nanotubes, KH550, pterin-6-carboxylic acid, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, N-hydroxysuccinimide, and diphenylphosphinyl chloride is 10-20:2-4:3-5:1-2:1-2:8-12; the heating reaction temperature is 40-60°C, and the reaction time is 2-4h; the temperature of the warming reaction is 60-80°C, and the reaction time is 3-6h; the stirring reaction temperature is 0-20°C, and the reaction time is 1-2h.

[0009] The modified carbon nanotubes of the present invention significantly improve their uniform distribution in the coating and avoid agglomeration. This uniform dispersion not only brings excellent physical enhancement effects to the coating, such as significantly improving the mechanical strength, hardness, wear resistance, crack resistance and adhesion to the substrate of the coating, making the coating more durable and thus extending the service life of the ecological density board, but also, by grafting pterin-6-carboxylic acid and diphenylphosphine chloride to form a nitrogen-phosphorus flame retardant on its surface, the synergistic effect with the carbon nanotubes can significantly improve the flame retardant properties of the environmentally friendly coating. When encountering a fire source, the modified carbon nanotubes can effectively promote charring, isolate oxygen, dilute combustible gases and absorb heat, thereby effectively suppressing the spread of flames and improving the fire safety of the density board.

[0010] Preferably, the negative ion powder is tourmaline powder treated with a silane coupling agent; tourmaline can permanently generate negative ions due to the presence of variable valence metals in its structure, remove harmful pollutants such as formaldehyde released by wood fibers, and effectively improve air quality. By treating it with a silane coupling agent, its interfacial compatibility can be improved.

[0011] Preferably, the dispersant is at least one of alkylphenol polyoxyethylene ether and sodium alkylaryl sulfonate.

[0012] Preferably, the defoaming agent is at least one of a phosphate hydrophobic defoaming agent, polysiloxane, and an organic alcohol compound.

[0013] Preferably, the thickener is at least one of hydroxyethyl cellulose and methyl cellulose.

[0014] The present invention also discloses a method for preparing the environmentally friendly coating, which comprises the following steps: The raw materials are weighed according to the formula, and the water-based acrylic resin, negative ion powder, modified carbon nanotubes, dispersant, water, defoamer, thickener and propylene glycol methyl ether acetate are mixed and stirred evenly to obtain an environmentally friendly coating.

[0015] The present invention also discloses a method for preparing the ecological density board, which comprises the following steps: Epoxy resin, nano-calcium carbonate and modified titanium dioxide are stirred and mixed evenly, then wood fiber and curing agent are added and continued to be stirred evenly to obtain a premix, which is then added to a mold. After paving, it is pre-pressed and hot-pressed. After forming, it is trimmed and polished to obtain a density board. Environmentally friendly paint is evenly applied on the density board, and the ecological density board is obtained after the environmentally friendly paint is dried and cured.

[0016] Preferably, the mass ratio of the epoxy resin, nano-calcium carbonate, modified titanium dioxide, wood fiber, and curing agent is 30-50:25-45:5-10:80-100:8-15.

[0017] Further preferably, the preparation method of the modified titanium dioxide is as follows: Titanium dioxide powder is dispersed in an ethanol aqueous solution, γ-glycidyloxypropyltrimethoxysilane is added, and the reaction is stirred. The obtained solid product is added to N,N-dimethylformamide, followed by 4-aminobenzophenone. The reaction is heated, filtered, and the solid is collected, washed, and dried to obtain modified titanium dioxide.

[0018] Further preferably, the mass ratio of titanium dioxide, γ-glycidyloxypropyltrimethoxysilane, and 4-aminobenzophenone is 15-25:3-6:4-7; the stirring reaction temperature is 40-60° C., and the reaction time is 3-5 h; the heating reaction temperature is 30-50° C., and the reaction time is 2-4 h.

[0019] Titanium dioxide is a flame retardant filler. By improving titanium dioxide and grafting 4-aminobenzophenone on its surface, the benzophenone UV protective group is added to the surface of titanium dioxide, which is not easy to migrate out, thereby improving the aging resistance of the density board.

[0020] Preferably, the pre-pressing condition is 60-70° C. and 3-5 MPa for 30-50 seconds, and the hot pressing condition is 135-145° C. and 4-6 MPa for 3-5 minutes.

[0021] Preferably, the spraying thickness of the environmentally friendly coating is 100-300 μm.

[0022] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention provides an ecological density board. By coating the surface of the density board with an environmentally friendly coating, the durability and flame retardancy of the ecological board can be improved. The environmentally friendly coating can continuously release negative ions, remove harmful pollutants such as formaldehyde released by wood fibers, and effectively improve air quality. The environmentally friendly coating used has a dense film formation and high mechanical strength, which can effectively improve the overall performance and service life of the ecological density board. At the same time, by introducing functional components such as modified titanium dioxide and carbon nanotubes, the coating has excellent aging resistance and flame retardancy. In addition, the system uses environmentally friendly solvents, reduces VOC emissions, and conforms to the concept of green environmental protection. (2) The preparation of the modified titanium dioxide of the present invention is firstly to modify the surface of titanium dioxide by γ-glycidyloxypropyltrimethoxysilane, introduce epoxy groups on its surface, and then react with the amino groups on 4-aminobenzophenone to graft 4-aminobenzophenone onto titanium dioxide. The benzophenone group can absorb ultraviolet rays to inhibit photodegradation and release energy in the form of heat energy, which is beneficial to improving the aging resistance of the environmentally friendly coating and is not easy to migrate out, thereby preventing the environmentally friendly coating from aging and yellowing, which causes the coating performance to deteriorate; (3) The preparation of the modified carbon nanotubes of the present invention is first to oxidize and etch the carbon nanotubes with concentrated nitric acid to increase their surface activity, and then treat them with KH550 to introduce amino groups on their surfaces. Under the action of carboxyl activators 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide, the carboxyl groups on pterin-6-carboxylic acid react with the amino groups on the carbon nanotubes to graft pterin-6-carboxylic acid onto the carbon nanotubes. The heteroatoms on the pterin structural unit can form hydrogen bonds with the polar groups on the wood fiber and provide the flame retardant element N, so that the carbon nanotubes can be modified. On the one hand, the adhesion between the modified carbon nanotubes and the substrate is improved. When the density board is impacted, the stress can be effectively transferred from the matrix to the high-strength carbon nanotubes, and the initiation and expansion of cracks at the interface are suppressed. On the other hand, the amino group on pterin-6-carboxylic acid reacts with diphenylphosphinoyl chloride to graft nitrogen-phosphorus flame retardants on the carbon nanotubes, which synergistically improve the flame retardant properties of environmentally friendly coatings. When encountering a fire source, the modified carbon nanotubes can effectively promote carbonization, isolate oxygen, dilute combustible gases and absorb heat, thereby effectively suppressing the spread of flames and improving the fire safety of the density board. DETAILED DESCRIPTION

[0023] To avoid redundancy, the items used in the following examples are all commercially available products unless otherwise specified, and the methods used are all conventional methods unless otherwise specified.

[0024] The sources of some raw materials used in the present invention are as follows: Water-based acrylic resin, brand J-676, was purchased from Jining Tangyi Chemical Co., Ltd.; titanium dioxide, particle size of 10 nm, rutile type, was purchased from Hangzhou Hengge Nanotechnology Co., Ltd.; tourmaline powder, 325 mesh, was purchased from Shijiazhuang Fenghua Mineral Products Co., Ltd.; carbon nanotubes, single-arm, tube diameter of 1-2 nm, length of 5-20 μm, were purchased from Zhongke Leiming (Beijing) Technology Co., Ltd.; epoxy resin, E44, was purchased from Shandong Bairong New Materials Technology Co., Ltd.; nano-calcium carbonate, heavy calcium carbonate, 800 mesh, was purchased from Lingshou County Yongshun Mineral Products Processing Plant.

[0025] Example 1 A method for preparing an ecological density board comprises the following steps: 40g of epoxy resin, 30g of nano-calcium carbonate, and 7.5g of modified titanium dioxide are stirred and mixed evenly, and then 90g of wood fiber and 10g of methyltetrahydrophthalic anhydride are added and continued to be stirred evenly to obtain a premix, which is then added to a mold, pre-pressed and hot-pressed after paving, trimmed and polished after molding to obtain a density board, and an environmentally friendly paint with a thickness of 200μm is evenly coated on the density board. After the environmentally friendly paint is dried and cured, an ecological density board is obtained; the pre-pressing conditions are pre-pressing at 65°C and 4MPa for 40s, and the hot pressing conditions are hot pressing at 140°C and 5MPa for 4min.

[0026] The preparation method of the environmentally friendly coating is as follows: 60 g of waterborne acrylic resin, 2 g of negative ion powder, 10 g of modified carbon nanotubes, 0.1 g of tristyrylphenol polyoxyethylene ether, 10 g of water, 0.4 g of tributyl phosphate, 0.1 g of hydroxyethyl cellulose, and 0.5 g of propylene glycol methyl ether acetate were mixed and stirred uniformly to obtain an environmentally friendly coating.

[0027] The preparation method of the modified titanium dioxide is as follows: 20 g of titanium dioxide powder was dispersed in 200 mL of 50 wt% ethanol aqueous solution, 4.3 g of γ-glycidyloxypropyltrimethoxysilane was added, and the mixture was stirred and reacted at 50 ° C for 4 h. The mixture was filtered, and the solid was collected, washed, and dried, and then added to 200 mL of N,N-dimethylformamide. Then, 5.5 g of 4-aminobenzophenone was added, and the mixture was heated at 40 ° C for 3 h. The mixture was filtered, and the solid was collected, washed, and dried to obtain modified titanium dioxide.

[0028] The preparation method of the negative ion powder is as follows: 10g of tourmaline powder and 100mL of ethanol are mixed and stirred at a speed of 300rpm for 30min, then 1g of KH550 is added, and the temperature is raised to 60°C and stirred under reflux for 2h, and then the solid is collected by filtration and dried to obtain the modified negative ion powder.

[0029] The preparation method of the modified carbon nanotubes is as follows: 25g of carbon nanotubes were dispersed in 100ml of concentrated nitric acid, ultrasonically treated for 30min, stirred at 80℃ for 4h, cooled to room temperature, filtered, washed with water until neutral, and dried to obtain pretreated carbon nanotubes; 15g of pretreated carbon nanotubes were mixed evenly with 200mL of 50wt% ethanol aqueous solution, 3.2g of KH550 was added, heated at 50℃ for 3h, filtered, the solid was collected, washed and dried, and added to 200mL of N,N-dimethylformamide, 4.2g of pterin-6-carboxylic acid, 1.3g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, 1.3g of N-hydroxysuccinimide was heated to 70°C and reacted for 4 hours. The mixture was filtered, the solids were collected, washed, dried, and dispersed in 200 mL of chloroform. 3.5 g of triethylamine was added and the mixture was stirred evenly. 10 g of diphenylphosphinoyl chloride was added dropwise and stirred at 10°C for 1.5 hours. After the reaction was completed, the solids were collected by filtration, washed, and dried to obtain modified carbon nanotubes.

[0030] Example 2 A method for preparing an ecological density board comprises the following steps: 30g of epoxy resin, 25g of nano-calcium carbonate, and 5g of modified titanium dioxide are stirred and mixed evenly, and then 80g of wood fiber and 8g of methyltetrahydrophthalic anhydride are added and continued to be stirred evenly to obtain a premix, which is then added to a mold, pre-pressed and hot-pressed after paving, trimmed and polished after molding to obtain a density board, and an environmentally friendly paint with a thickness of 100μm is evenly coated on the density board. After the environmentally friendly paint is dried and cured, an ecological density board is obtained; the pre-pressing conditions are pre-pressing at 60°C and 5MPa for 30s, and the hot pressing conditions are hot pressing at 135°C and 6MPa for 3min.

[0031] The preparation method of the environmentally friendly coating is as follows: 50 g of water-based acrylic resin, 1 g of negative ion powder, 5 g of modified carbon nanotubes, 0.01 g of tristyrylphenol polyoxyethylene ether, 5 g of water, 0.1 g of tributyl phosphate, 0.01 g of methyl cellulose, and 0.1 g of propylene glycol methyl ether acetate were mixed and stirred uniformly to obtain an environmentally friendly coating.

[0032] The preparation method of the modified titanium dioxide is as follows: 15 g of titanium dioxide powder was dispersed in 200 mL of 50 wt% ethanol aqueous solution, 3 g of γ-glycidyloxypropyltrimethoxysilane was added, and the mixture was stirred and reacted at 40 ° C for 5 h. The mixture was filtered, the solid was collected, washed and dried, and then added to 200 mL of N, N-dimethylformamide. Then, 4 g of 4-aminobenzophenone was added, and the mixture was heated at 30 ° C for 4 h. The mixture was filtered, the solid was collected, washed and dried to obtain modified titanium dioxide.

[0033] The preparation method of the negative ion powder is as follows: 10g of tourmaline powder and 100mL of ethanol are mixed and stirred at a speed of 300rpm for 30min, then 1g of KH550 is added, and the temperature is raised to 60°C and stirred under reflux for 2h, and then the solid is collected by filtration and dried to obtain the modified negative ion powder.

[0034] The preparation method of the modified carbon nanotubes is as follows: 25 g of carbon nanotubes were dispersed in 100 ml of concentrated nitric acid, ultrasonically treated for 30 min, stirred at 80 ° C for 4 h, cooled to room temperature, filtered, washed with water until neutral, and dried to obtain pretreated carbon nanotubes; 10 g of pretreated carbon nanotubes were mixed evenly with 200 mL of 50 wt% ethanol aqueous solution, 2 g of KH550 was added, and the mixture was heated at 50 ° C for 3 h. The mixture was filtered, the solid was collected, washed, and dried, and then added to 200 mL of N,N-dimethylformamide. 3 g of pterin-6-carboxylic acid, 1 g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, and 1 g of N-hydroxysuccinimide were added. The mixture was heated to 60 ° C for 6 h. The mixture was filtered, the solid was collected, washed, and dried, and then dispersed in 200 mL of chloroform. 3.5 g of triethylamine was added and the mixture was stirred evenly. 8 g of diphenylphosphinyl chloride was added dropwise, and the mixture was stirred at 0 ° C for 2 h. After the reaction was completed, the solid was filtered, collected, washed, and dried to obtain modified carbon nanotubes.

[0035] Example 3 A method for preparing an ecological density board comprises the following steps: 50g of epoxy resin, 45g of nano-calcium carbonate, and 10g of modified titanium dioxide are stirred and mixed evenly, and then 100g of wood fiber and 13g of methyltetrahydrophthalic anhydride are added and continued to be stirred evenly to obtain a premix, which is then added to a mold, pre-pressed and hot-pressed after paving, trimmed and polished after molding to obtain a density board, and an environmentally friendly paint with a thickness of 300μm is evenly coated on the density board. After the environmentally friendly paint is dried and cured, an ecological density board is obtained; the pre-pressing conditions are pre-pressing at 70°C and 5MPa for 30s, and the hot pressing conditions are hot pressing at 145°C and 4MPa for 5min.

[0036] The preparation method of the environmentally friendly coating is as follows: 70 g of water-based acrylic resin, 3 g of negative ion powder, 15 g of modified carbon nanotubes, 0.2 g of tristyrylphenol polyoxyethylene ether, 15 g of water, 0.5 g of defoamer, 0.2 g of tristyrylphenol polyoxyethylene ether, and 1 g of propylene glycol methyl ether acetate were mixed and stirred uniformly to obtain an environmentally friendly coating.

[0037] The preparation method of the modified titanium dioxide is as follows: 25 g of titanium dioxide powder was dispersed in 200 mL of 50 wt% ethanol aqueous solution, 6 g of γ-glycidyloxypropyltrimethoxysilane was added, and the mixture was stirred and reacted at 50 ° C for 4 h. The mixture was filtered, the solid was collected, washed and dried, and then added to 200 mL of N, N-dimethylformamide. Then, 7 g of 4-aminobenzophenone was added, and the mixture was heated at 50 ° C for 2 h. The mixture was filtered, the solid was collected, washed and dried to obtain modified titanium dioxide.

[0038] The preparation method of the negative ion powder is as follows: 10g of tourmaline powder and 100mL of ethanol are mixed and stirred at a speed of 300rpm for 30min, then 1g of KH550 is added, and the temperature is raised to 60°C and stirred under reflux for 2h, and then the solid is collected by filtration and dried to obtain the modified negative ion powder.

[0039] The preparation method of the modified carbon nanotubes is as follows: 25 g of carbon nanotubes were dispersed in 100 ml of concentrated nitric acid, ultrasonically treated for 30 min, stirred at 80 ° C for 4 h, cooled to room temperature, filtered, washed with water until neutral, and dried to obtain pretreated carbon nanotubes; 20 g of pretreated carbon nanotubes were mixed evenly with 200 mL of 50 wt% ethanol aqueous solution, 4 g of KH550 was added, and the mixture was heated at 60 ° C for 2 h. The mixture was filtered, the solid was collected, washed, and dried, and then added to 200 mL of N,N-dimethylformamide. 5 g of pterin-6-carboxylic acid, 2 g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, and 2 g of N-hydroxysuccinimide were added, and the mixture was heated to 80 ° C for 3 h. The mixture was filtered, the solid was collected, washed, and dried, and then dispersed in 200 mL of chloroform. 5 g of triethylamine was added and the mixture was mixed and stirred evenly. 12 g of diphenylphosphinyl chloride was added dropwise, and the mixture was stirred at 20 ° C for 1 h. After the reaction was completed, the solid was collected by filtration, washed, and dried to obtain modified carbon nanotubes.

[0040] Comparative Example 1 A method for preparing an ecological density board comprises the following steps: 40g of epoxy resin, 30g of nano-calcium carbonate, and 7.5g of nano-titanium dioxide are stirred and mixed evenly, and then 90g of wood fiber and 10g of methyltetrahydrophthalic anhydride are added and continued to be stirred evenly to obtain a premix, which is then added to a mold, pre-pressed and hot-pressed after paving, trimmed and polished after molding to obtain a density board, and an environmentally friendly paint with a thickness of 200μm is evenly coated on the density board. After the environmentally friendly paint is dried and cured, an ecological density board is obtained; the pre-pressing conditions are pre-pressing at 65°C and 4MPa for 40s, and the hot pressing conditions are hot pressing at 140°C and 5MPa for 4min.

[0041] The preparation method of the environmentally friendly coating is as follows: 60 g of waterborne acrylic resin, 2 g of negative ion powder, 10 g of modified carbon nanotubes, 0.1 g of tristyrylphenol polyoxyethylene ether, 10 g of water, 0.4 g of tributyl phosphate, 0.1 g of hydroxyethyl cellulose, and 0.5 g of propylene glycol methyl ether acetate were mixed and stirred uniformly to obtain an environmentally friendly coating.

[0042] The preparation method of the negative ion powder is as follows: 10g of tourmaline powder and 100mL of ethanol are mixed and stirred at a speed of 300rpm for 30min, then 1g of KH550 is added, and the temperature is raised to 60°C and stirred under reflux for 2h, and then the solid is collected by filtration and dried to obtain the modified negative ion powder.

[0043] The preparation method of the modified carbon nanotubes is as follows: 25g of carbon nanotubes were dispersed in 100ml of concentrated nitric acid, ultrasonically treated for 30min, stirred at 80℃ for 4h, cooled to room temperature, filtered, washed with water until neutral, and dried to obtain pretreated carbon nanotubes; 15g of pretreated carbon nanotubes were mixed evenly with 200mL of 50wt% ethanol aqueous solution, 3.2g of KH550 was added, heated at 50℃ for 3h, filtered, the solid was collected, washed and dried, and added to 200mL of N,N-dimethylformamide, 4.2g of pterin-6-carboxylic acid, 1.3g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, 1.3g of N-hydroxysuccinimide was heated to 70°C and reacted for 4 hours. The mixture was filtered, the solids were collected, washed, dried, and dispersed in 200 mL of chloroform. 3.5 g of triethylamine was added and the mixture was stirred evenly. 10 g of diphenylphosphinoyl chloride was added dropwise and stirred at 10°C for 1.5 hours. After the reaction was completed, the solids were collected by filtration, washed, and dried to obtain modified carbon nanotubes.

[0044] Comparative Example 2 A method for preparing an ecological density board comprises the following steps: 40g of epoxy resin, 30g of nano-calcium carbonate, and 7.5g of modified titanium dioxide are stirred and mixed evenly, and then 90g of wood fiber and 10g of methyltetrahydrophthalic anhydride are added and continued to be stirred evenly to obtain a premix, which is then added to a mold, pre-pressed and hot-pressed after paving, trimmed and polished after molding to obtain a density board, and an environmentally friendly paint with a thickness of 200μm is evenly coated on the density board. After the environmentally friendly paint is dried and cured, an ecological density board is obtained; the pre-pressing conditions are pre-pressing at 65°C and 4MPa for 40s, and the hot pressing conditions are hot pressing at 140°C and 5MPa for 4min.

[0045] The preparation method of the environmentally friendly coating is as follows: 60 g of water-based acrylic resin, 2 g of negative ion powder, 10 g of carbon nanotubes, 0.1 g of tristyrylphenol polyoxyethylene ether, 10 g of water, 0.4 g of tributyl phosphate, 0.1 g of hydroxyethyl cellulose, and 0.5 g of propylene glycol methyl ether acetate were mixed and stirred uniformly to obtain an environmentally friendly coating.

[0046] The preparation method of the modified titanium dioxide is as follows: 20 g of titanium dioxide powder was dispersed in 200 mL of 50 wt% ethanol aqueous solution, 4.3 g of γ-glycidyloxypropyltrimethoxysilane was added, and the mixture was stirred at 50 ° C for 4 h. After filtering, the solid was collected, washed and dried, and then added to 200 mL of N, N-dimethylformamide. Then, 5.5 g of 4-aminobenzophenone was added, and the mixture was heated at 40 ° C for 3 h. After filtering, the solid was collected, washed and dried to obtain modified titanium dioxide.

[0047] The preparation method of the negative ion powder is as follows: 10g of tourmaline powder and 100mL of ethanol are mixed and stirred at a speed of 300rpm for 30min, then 1g of KH550 is added, and the temperature is raised to 60°C and stirred under reflux for 2h, and then the solid is collected by filtration and dried to obtain the modified negative ion powder.

[0048] Comparative Example 3 A method for preparing an ecological density board comprises the following steps: 40g of epoxy resin, 30g of nano-calcium carbonate, and 7.5g of modified titanium dioxide are stirred and mixed evenly, and then 90g of wood fiber and 10g of methyltetrahydrophthalic anhydride are added and continued to be stirred evenly to obtain a premix, which is then added to a mold, pre-pressed and hot-pressed after paving, trimmed and polished after molding to obtain a density board, and an environmentally friendly paint with a thickness of 200μm is evenly coated on the density board. After the environmentally friendly paint is dried and cured, an ecological density board is obtained; the pre-pressing conditions are pre-pressing at 65°C and 4MPa for 40s, and the hot pressing conditions are hot pressing at 140°C and 5MPa for 4min.

[0049] The preparation method of the environmentally friendly coating is as follows: 60 g of waterborne acrylic resin, 2 g of negative ion powder, 10 g of modified carbon nanotubes, 0.1 g of tristyrylphenol polyoxyethylene ether, 10 g of water, 0.4 g of tributyl phosphate, 0.1 g of hydroxyethyl cellulose, and 0.5 g of propylene glycol methyl ether acetate were mixed and stirred uniformly to obtain an environmentally friendly coating.

[0050] The preparation method of the modified titanium dioxide is as follows: 20 g of titanium dioxide powder was dispersed in 200 mL of 50 wt% ethanol aqueous solution, 4.3 g of γ-glycidyloxypropyltrimethoxysilane was added, and the mixture was stirred at 50 ° C for 4 h. After filtering, the solid was collected, washed and dried, and then added to 200 mL of N, N-dimethylformamide. Then, 5.5 g of 4-aminobenzophenone was added, and the mixture was heated at 40 ° C for 3 h. After filtering, the solid was collected, washed and dried to obtain modified titanium dioxide.

[0051] The preparation method of the negative ion powder is as follows: 10g of tourmaline powder and 100mL of ethanol are mixed and stirred at a speed of 300rpm for 30min, then 1g of KH550 is added, and the temperature is raised to 60°C and stirred under reflux for 2h, and then the solid is collected by filtration and dried to obtain the modified negative ion powder.

[0052] The preparation method of the modified carbon nanotubes is as follows: 25g of carbon nanotubes were dispersed in 100ml of concentrated nitric acid, ultrasonically treated for 30min, stirred at 80°C for 4h, cooled to room temperature, filtered, washed with water until neutral, and dried to obtain pretreated carbon nanotubes; 15g of pretreated carbon nanotubes were mixed evenly with 200mL of 50wt% ethanol aqueous solution, 3.2g of KH550 was added, heated at 50°C for 3h, filtered, the solid was collected, washed and dried, and then added to 200mL of chloroform, 3.5g of triethylamine was added and mixed evenly, 10g of diphenylphosphinoyl chloride was added dropwise, and the reaction was stirred at 10°C for 1.5h. After the reaction was completed, the solid was collected by filtration, washed and dried to obtain modified carbon nanotubes.

[0053] 1. Environmentally friendly coating performance test The environmentally friendly coatings prepared in Examples 1-3 of the present invention and Comparative Examples 1-3 were applied to tinplate having a size of 155 mm × 70 mm × 0.20 mm, placed at 50° C. for curing for 10 hours, and cooled to obtain a paint film. The pencil hardness was tested using an HT-1086 pencil hardness tester according to the test method of standard GB / T6739-2022, and the adhesion was tested according to the test method of standard reference GB / T5210-2006; the impact strength was tested using a GS-CJQD impact strength tester according to the test method of standard GB / T1732-2020. Three samples were tested for each embodiment or comparative example, and the results were averaged. The test data are shown in Table 1: Table 1 Test results of environmentally friendly coating performance Pencil hardness (H) Adhesion (MPa) Impact strength (kg / cm-2) Example 1 4 9.2 6.3 Example 2 4 8.9 6.0 Example 3 4 9.3 6.2 Comparative Example 1 4 7.6 5.6 Comparative Example 2 2 6.5 4.8 Comparative Example 3 3 7.2 5.4 2. Aging resistance and flame retardant performance test The ecological density boards prepared in Examples 1-3 and Comparative Examples 1-2 were subjected to artificial weathering tests in accordance with GB / T1865-2009 and evaluated in accordance with GB / T1766-2008. At the same time, the vertical burning (UL94) grade was tested in accordance with ASTM3801. The data obtained are shown in Table 2 below.

[0054] Table 2 Test results of aging resistance and flame retardancy of ecological density board Aging resistance Flame retardant grade Example 1 No blistering, no peeling, no cracks, powdering level 1 V-0 Example 2 No blistering, no peeling, no cracks, powdering level 1 V-0 Example 3 No blistering, no peeling, no cracks, powdering level 1 V-0 Comparative Example 1 There are a large number of bubbles, the peeling area is greater than 20%, there are intensive cracks, and the powdering is level 2 V-1 Comparative Example 2 No blistering, no peeling, no cracks, powdering level 1 V-2 Comparative Example 3 No blistering, no peeling, no cracks, powdering level 1 V-1 It can be seen from the experimental results in Table 1 and Table 2 that the environmentally friendly coating prepared by the present invention has good adhesion and mechanical properties, and the ecological density board prepared by the present invention has good aging resistance and flame retardant properties.

[0055] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of the present invention.

Claims

1. An ecological density board, characterized in that: The invention comprises a density board and an environmentally friendly coating coated on the surface of the density board; the environmentally friendly coating comprises the following components in parts by weight: 50-70 parts of water-based acrylic resin, 1-3 parts of negative ion powder, 5-15 parts of modified carbon nanotubes, 0.01-0.2 parts of dispersant, 5-15 parts of water, 0.1-0.5 parts of defoaming agent, 0.01-0.2 parts of thickener, and 0.1-1 parts of propylene glycol methyl ether acetate.

2. The ecological density board according to claim 1, characterized in that: The preparation method of the modified carbon nanotubes is as follows: The carbon nanotubes are dispersed in concentrated nitric acid, heated and stirred by ultrasonic treatment, cooled to room temperature, filtered, the solid matter is collected, washed with water until neutral, and dried to obtain pretreated carbon nanotubes; After the pretreated carbon nanotubes and the ethanol aqueous solution are evenly mixed, KH550 is added and heated to react. The obtained solid product is added to N,N-dimethylformamide, pterin-6-carboxylic acid, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide are added, the temperature is increased to react, and the product is filtered. The solid is collected, washed and dried, and then dispersed in chloroform. Triethylamine is added and the mixture is stirred evenly. Diphenylphosphine chloride is added dropwise and the mixture is stirred to react. After the reaction is completed, the product is washed with water, filtered and collected, and the solid is washed and dried to obtain the modified carbon nanotubes.

3. The ecological density board according to claim 2, characterized in that: The mass ratio of the pretreated carbon nanotubes, KH550, pterin-6-carboxylic acid, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, N-hydroxysuccinimide, and diphenylphosphinyl chloride is 10-20:2-4:3-5:1-2:1-2:8-12.

4. The ecological density board according to claim 1, characterized in that: The dispersant is at least one of alkylphenol polyoxyethylene ether and sodium alkyl aryl sulfonate.

5. The ecological density board according to claim 1, characterized in that: The thickener is at least one of hydroxyethyl cellulose and methyl cellulose.

6. The ecological density board according to claim 1, characterized in that: The preparation method of the environmentally friendly coating comprises the following steps: The components are weighed according to the formula, and the water-based acrylic resin, negative ion powder, modified carbon nanotubes, dispersant, water, defoamer, thickener and propylene glycol methyl ether acetate are mixed and stirred evenly to obtain an environmentally friendly coating.

7. A method for preparing the ecological density board according to any one of claims 1 to 5, characterized in that: The method comprises the following steps: uniformly stirring epoxy resin, nano-calcium carbonate and modified titanium dioxide, then adding wood fiber and curing agent and continuing to stir uniformly to obtain a premix, then adding the premix into a mold, pre-pressing and hot-pressing the premix after paving, trimming and polishing the premix after forming to obtain a density board, uniformly coating the density board with an environmentally friendly paint, and obtaining an ecological density board after the environmentally friendly paint is dried and solidified.

8. The preparation method according to claim 7, characterized in that: The mass ratio of the epoxy resin, nano-calcium carbonate, modified titanium dioxide, wood fiber and curing agent is 30-50:25-45:5-10:80-100:8-15.

9. The preparation method according to claim 7 or 8, characterized in that The preparation method of the modified titanium dioxide is as follows: dispersing titanium dioxide powder in an ethanol aqueous solution, adding γ-glycidyloxypropyltrimethoxysilane, stirring and reacting, adding the obtained solid product to N,N-dimethylformamide, then adding 4-aminobenzophenone, heating and reacting, filtering, collecting the solid, washing and drying to obtain the modified titanium dioxide.

10. The preparation method according to claim 9, characterized in that: The mass ratio of the titanium dioxide, γ-glycidyloxypropyltrimethoxysilane and 4-aminobenzophenone is 15-25:3-6:4-7.