High wear-resistant melamine impregnated decorative paper and method for preparing the same

Abstract

The application discloses high-wear-resistance melamine impregnated decorative paper and a preparation method thereof, and belongs to the technical field of decorative materials. The preparation method comprises the following steps: S1, preheating and argon / oxygen low-temperature plasma treatment of raw paper; S2, impregnation of modified melamine formaldehyde resin and pre-drying to semi-curing; S3, spraying of KH-560 ethanol solution on the surface of the semi-curing layer to form an interface bonding layer; S4-S6, preparation of first, second and third wear-resistant layer coating liquids respectively, and gradient coating of the three layers of coating liquids on the interface bonding layer in sequence, and pre-drying and drying are performed to obtain the high-wear-resistance melamine impregnated decorative paper. Through the synergistic effect of the modified resin, the interface chemical bonding and the three-layer gradient wear-resistant layer, the wear resistance of the decorative paper is significantly improved, meanwhile, the decorative paper has good crack resistance, impact resistance and crack resistance, and can be widely applied to high-wear-resistance requirement fields such as reinforced wood floor, furniture veneer and cabinet board.

Description

Technical Field

[0001] This invention belongs to the field of decorative materials technology, specifically relating to a highly abrasion-resistant melamine-impregnated decorative paper and its preparation method. Background Technology

[0002] In recent years, my country's wood-based panel manufacturing industry has maintained steady development, with an average annual growth rate of 4.55% in output, accounting for more than 60% of the world's annual output. Currently, China ranks first globally in wood-based panel production, consumption, and import / export trade volume. Wood-based panels reduce timber resource consumption, offering both economic benefits and affordability. However, due to their dull, colorless surface and poor water, moisture, abrasion, and corrosion resistance, raw wood-based panels cannot be used directly and usually require surface decoration. Various decorative materials are used, such as veneer, pre-painted paper, impregnated paper, and hot-pressed wood foil. Approximately 70% of particleboard and fiberboard use impregnated paper for surface decoration. Currently, impregnated paper is the most consumed decorative material. Among these, melamine-formaldehyde (MF) resin impregnated paper dominates due to its excellent adhesion and water resistance, and is of significant research importance. Melamine-impregnated decorative paper is widely used for surface decoration of laminate flooring, furniture veneers, cabinet panels, etc. Its surface not only needs to present clear textures and realistic colors, but also must possess excellent abrasion resistance to withstand friction, scratches, and wear during daily use. Abrasion resistance directly determines the product's lifespan, the durability of its decorative effect, and the consumer experience, and is one of the core technical indicators for measuring the quality of this type of product.

[0003] However, the cross-linked network formed after curing of conventional melamine-formaldehyde resin (MF resin) and modified melamine-urea-formaldehyde resin (MUF resin) is rigid and brittle, with concentrated internal stress, making the impregnated paper prone to micro-cracks or even breakage when bent or impacted. More importantly, this highly brittle matrix is ​​difficult to form a strong interfacial bond with added hard, wear-resistant particles (such as alumina and silicon carbide)—due to the large modulus difference between the particles and the resin, the particles are easily pulled out or pressed in during wear, becoming a source of crack initiation. This results in the abrasion resistance of traditional impregnated paper typically being below 300 revolutions, only meeting the needs of low-end products, with a short service life, which is detrimental to resource conservation and environmental protection. Even with softening modifications by adding plasticizers or isocyanates, it often comes at the cost of sacrificing surface hardness and heat resistance, failing to truly achieve a simultaneous improvement in crack resistance and abrasion resistance. Summary of the Invention

[0004] The purpose of this invention is to provide a highly wear-resistant melamine-impregnated decorative paper and its preparation method. The prepared impregnated decorative paper has significantly improved wear resistance while maintaining good crack resistance, impact resistance, crazing resistance, and hot-pressing bonding performance with boards. It can be widely used in fields with high wear resistance requirements, such as engineered wood flooring, furniture veneer panels, and cabinet panels.

[0005] To achieve the above technical objectives, the present invention adopts the following technical solution: A method for preparing highly abrasion-resistant melamine-impregnated decorative paper includes the following steps: S1, Pretreatment of base paper: The decorative base paper is preheated at 70-90℃ to a moisture content of 5%-8%, and then subjected to low-temperature plasma treatment for 1-3 minutes in an argon / oxygen mixed atmosphere. S2, Preparation of the impregnated reinforcing layer: The pretreated base paper is passed through the impregnation tank at a speed of 15-25 m / min, impregnated with modified melamine-formaldehyde resin, and the impregnation amount is controlled at 80-120 g / m. 2 Then pre-dry at 100-120℃ for 20-40 seconds to allow the impregnated layer to reach a semi-cured state. S3, Interface Bonding Layer Spraying: Spray KH-560 ethanol solution onto the surface of the semi-cured impregnated reinforcing layer, with a spraying amount of 1-2 g / m². 2 ; S4, Preparation of the first wear-resistant coating liquid: Modified nano silica, polybutadiene modified epoxy resin and modified melamine formaldehyde resin are mixed in a mass ratio, and a dispersant of 0.3%-0.8% of the mass of modified melamine formaldehyde resin is added and dispersed at high speed and uniformly. S5, Preparation of the second wear-resistant coating liquid: Modified basalt fiber and silicon carbide are mixed in a certain mass ratio to obtain a solid mixture. The solid mixture is mixed with modified melamine-formaldehyde resin in a mass ratio of 3:7. A dispersant of 0.3%-0.8% of the mass of modified melamine-formaldehyde resin is added and dispersed at high speed for uniform dispersion. S6, Preparation of the third wear-resistant layer coating liquid: Mix waterborne polyurethane and modified melamine-formaldehyde resin at a mass ratio of 3: (5-7), then add 1%-3% of modified nano-silica, which accounts for 1%-3% of the total mass of waterborne polyurethane and modified melamine-formaldehyde resin, and ultrasonically disperse for 15-30 min to obtain the third wear-resistant layer coating liquid. S7, Gradient Coating and Drying: Using reverse roller coating or curtain coating methods, the first abrasion-resistant layer coating liquid, the second abrasion-resistant layer coating liquid, and the third abrasion-resistant layer coating liquid are sequentially coated onto the semi-cured impregnated reinforcing decorative paper after the spraying treatment in step S3, with coating amounts of 8–15 g / m² respectively. 2 10~18 g / m 2 5~12 g / m 2After each coating layer is applied, it is pre-dried at 80–100℃ for 30–60 seconds. After the last coating layer is applied, it is directly dried at 80–100℃ to obtain the final product.

[0006] Preferably, the modified melamine-formaldehyde resin is prepared by the following method: A. Add water and 37% formaldehyde solution to the reaction vessel, stir, adjust the pH to 8.5-9.0 with 10% NaOH solution, raise the temperature to 75-80℃, add melamine in three batches, control the temperature not to exceed 85℃, keep the reaction at the temperature for 30-45 minutes, and obtain a clear and transparent reaction solution. B. After cooling the reaction solution obtained in step A to 70-75℃, add p-toluenesulfonic acid dissolved in a small amount of ethanol. Adjust the pH to 7.5-8.0 with 10% NaOH solution. Slowly add diallyl adipate over 15-20 minutes. Then, raise the temperature to 80-85℃ and react for 60-90 minutes. Add diethylene glycol and continue the reaction for 20-30 minutes. Then, add hydroquinone as a polymerization inhibitor and maintain the temperature until the water dilution reaches 2.5-3.0. Terminate the reaction and cool the system to below 40℃. Adjust the pH to 8.5-9.0 with 10% NaOH solution before discharging.

[0007] Preferably, the modified melamine-formaldehyde resin contains the following components by weight: 100-110 parts melamine, 170-200 parts 37% formaldehyde solution, 10-15 parts diallyl adipate, 50-70 parts water, 0.1-0.3 parts p-toluenesulfonic acid, 0.05-0.1 parts hydroquinone, and 3-5 parts diethylene glycol.

[0008] Preferably, the mass concentration of the KH-560 ethanol solution in step S3 is 1-1.5%.

[0009] Preferably, the mass composition of each raw material in the first wear-resistant layer coating liquid in step S4 is as follows: 10-15 parts of modified nano silica, 5-10 parts of polybutadiene-modified epoxy resin, and 75-80 parts of modified melamine-formaldehyde resin.

[0010] Preferably, the modified nano-silica is nano-silica modified with silane coupling agent KH-560.

[0011] Preferably, the mass ratio of modified basalt fiber to silicon carbide in step S5 is 1:(2-3).

[0012] Preferably, the modified basalt fiber is prepared by the following method: basalt fiber treated with acetone desizing is added to a dopamine hydrochloride aqueous solution according to the solid-liquid ratio, then the pH is adjusted to 8.5 using 1 mol / L Tris buffer, ultrasonically dispersed for 15-20 min, and then magnetically stirred for 20-24 h. After being taken out and washed 3-4 times with deionized water, it is dried to obtain the modified basalt fiber.

[0013] Preferably, the solid-liquid ratio of the basalt fiber to the dopamine hydrochloride aqueous solution is 1g:10mL; and the mass concentration of the dopamine hydrochloride aqueous solution is 2-3g / L.

[0014] The dispersant is selected from one or more of sodium polyacrylate, ammonium polyacrylate, alkylphenol polyoxyethylene ether, and fatty alcohol polyoxyethylene ether.

[0015] The high-wear-resistant melamine-impregnated decorative paper prepared by the above method has wear resistance and crack resistance far superior to traditional wear-resistant paper and decorative paper. It can be directly pressed onto the surface of the substrate, resulting in excellent product performance, high surface gloss and clarity, and significantly extended service life, with good market application prospects.

[0016] Compared with the prior art, the beneficial effects of the present invention are: 1) This invention uses diallyl adipate and diethylene glycol to composite modify melamine-formaldehyde resin, reducing the crosslinking density and internal stress after resin curing, and endowing it with appropriate flexibility and a higher density of active functional groups. On this basis, KH-560 ethanol solution is sprayed onto the surface of the semi-cured impregnation reinforcement layer to form an interfacial bonding layer rich in epoxy groups; the KH-560 modified nano-silica and polybutadiene modified epoxy resin in the first wear-resistant layer, and the KH-560 modified nano-silica in the third wear-resistant layer can all undergo epoxy-epoxy ring-opening crosslinking with the interfacial layer or form covalent bonds with the hydroxyl and amino groups in the resin, so that a continuous chemical bonding network is formed from the inside out between the impregnation layer, the first layer, the second layer, and the third layer, which completely overcomes the defect of traditional multilayer coatings that are easy to peel off between layers due to physical adsorption.

[0017] 2) The second wear-resistant layer of this invention is made by compounding polydopamine (PDA) modified basalt fibers and silicon carbide in a mass ratio of 1:2 to 1:3. The PDA coating introduces active groups such as catechol and amino groups on the surface of the basalt fibers, which significantly improves the interfacial wettability and chemical bonding strength between the fibers and the modified melamine-formaldehyde resin, and increases the surface roughness of the fibers, forming a mechanical interlock. During wear, the basalt fiber network acts as a skeleton, effectively dispersing and transferring stress and preventing crack propagation; the silicon carbide particles act as a hard shield to withstand the direct cutting of the abrasive. The complementary size and optimized ratio of the fibers and particles enable the second layer to maintain structural integrity and continuously exert its anti-wear effect under high-load wear. Compared with the system of unmodified basalt fibers or single silicon carbide filling, the wear resistance of the final impregnated decorative paper prepared by this invention is significantly improved.

[0018] 3) The three-layer gradient wear-resistant coating involved in this invention has a gradient transition in hardness and modulus between the three layers, avoiding stress concentration caused by abrupt changes in performance. Simultaneously, the polybutadiene-modified epoxy resin in the first layer and the waterborne polyurethane in the third layer are both flexible components, effectively alleviating the overall coating's brittleness. Testing shows that the impact height of the impregnated decorative paper from this invention is more than twice that of traditional products, and there are no surface cracks after hot pressing, meeting the complex processing requirements such as irregular edge sealing and curved surface shaping.

[0019] 4) This invention uses KH-560 silane coupling agent to surface modify inorganic nano-silica and PDA to deeply modify basalt fibers, effectively solving the interfacial compatibility problem between inorganic materials and organic resins. The particles and fibers are uniformly dispersed in the resin, without agglomeration or white spot defects. The coating surface is smooth, perfectly presenting the wood grain or printed texture of the decorative base paper without affecting the decorative effect. Furthermore, the parameter ranges for each step of this invention are clearly defined, the PDA coating process for modified basalt fibers is mild, requires no complex equipment, the raw materials are readily available, the cost is controllable, and it is easy to achieve continuous production on existing impregnated paper production lines. Detailed Implementation

[0020] The technical solution of the present invention will be further described below with reference to specific embodiments, but is not limited thereto. Unless otherwise specified, all reagents and raw materials used in the present invention are commercially available products, wherein the basalt fiber with a fiber length of 2-5mm was purchased from Sichuan Pawoke Mineral Fiber Products Co., Ltd.

[0021] Example 1 A highly abrasion-resistant melamine-impregnated decorative paper, the preparation method of which is as follows: S1 Base paper pretreatment: The decorative base paper is preheated at 70℃ to a moisture content of 5%, and then subjected to low-temperature plasma treatment in an argon / oxygen mixed atmosphere for 1 min.

[0022] S2 Impregnated Reinforcing Layer: Modified melamine-formaldehyde resin is impregnated at a speed of 15 m / min, with an impregnation amount of 80 g / m. 2 Pre-dry at 100℃ for 40 seconds until semi-cured.

[0023] S3 interfacial bonding layer: sprayed with 1.0% KH-560 ethanol solution, spraying amount 1 g / m 2 .

[0024] S4 First Wear-Resistant Layer Coating Solution: Mix 10 kg of modified nano-silica, 5 kg of polybutadiene-modified epoxy resin, and 75 kg of modified melamine-formaldehyde resin, then add 0.225 kg of sodium polyacrylate and disperse evenly at high speed.

[0025] S5 Second Wear-Resistant Layer Coating Solution: 1 kg of modified basalt fiber and 2 kg of silicon carbide are mixed, then 7 kg of modified melamine-formaldehyde resin is mixed, and 0.021 kg of sodium polyacrylate is added. The mixture is then dispersed at high speed until uniform.

[0026] S6 Third Wear-Resistant Layer Coating Solution: Mix 3 kg of waterborne polyurethane and 5 kg of modified melamine-formaldehyde resin, add 0.08 kg of modified nano-silica, and ultrasonically disperse for 15 min.

[0027] S7 Gradient Coating and Drying: Using reverse roller coating or curtain coating methods, the first abrasion-resistant layer coating liquid, the second abrasion-resistant layer coating liquid, and the third abrasion-resistant layer coating liquid are sequentially applied to the semi-cured impregnated reinforcing decorative paper after the spraying treatment in step S3. The coating amounts are 8 g / m², respectively. 2 10 g / m 2 5 g / m 2 Pre-dry each layer at 80℃ for 30 seconds, and finally dry at 80℃ to the finished product.

[0028] The modified melamine-formaldehyde resin is prepared by the following method: A. Add 50 kg of water and 170 kg of 37% formaldehyde solution to the reactor, stir well, and adjust the pH to 8.5 with 10% NaOH solution; raise the temperature to 75℃, add 100 kg of melamine in three batches, control the temperature not to exceed 85℃, and keep the reaction at this temperature for 30 min until the solution is clear and transparent.

[0029] B. After cooling the system to 70℃, dissolve 0.1 kg of p-toluenesulfonic acid in a small amount of ethanol and add it to the system. Adjust the pH to 7.5 with 10% NaOH solution. Slowly add 10 kg of diallyl adipate over 15 min. Heat the system to 80℃ and react for 60 min. Add 3 kg of diethylene glycol and continue the reaction for 20 min. Add 0.05 kg of hydroquinone and keep the system warm until the water dilution reaches 2.5. Cool the system to below 40℃ and adjust the pH to 8.5 with 10% NaOH solution. Discharge the product for later use.

[0030] The specific preparation method of the modified nano-silica is as follows: 1) Take 100 g of nano-silica (particle size 20~30 nm), dry and pretreat at 110℃ for 3 h, and set aside for later use; 2) Dissolve 5g of KH-560 silane coupling agent in 50 mL of ethanol / water mixed solvent (ethanol to water volume ratio of 7:1), adjust the pH to 4.5 with glacial acetic acid, and hydrolyze at room temperature for 20 min to obtain KH-560 hydrolysate; 3) Add the dried nano-silica to 1500 mL of anhydrous ethanol and ultrasonically disperse for 20 min to obtain nano-SiO2 dispersion. 4) Under stirring, the KH-560 hydrolysate was slowly added dropwise to the nano-SiO2 dispersion. After the addition was complete, the temperature was raised to 80℃ and the reaction was stirred at a constant temperature for 6 h. After the reaction was completed, the mixture was centrifuged, washed three times with anhydrous ethanol, dried under vacuum at 70℃ to constant weight, ground and sieved to obtain KH-560 modified nano-silica.

[0031] The modified basalt fiber is prepared by the following method: basalt fiber desizing with acetone is added to a 2 g / L dopamine hydrochloride aqueous solution at a solid-liquid ratio of 1 g: 10 mL. The pH is then adjusted to 8.5 using 1 mol / L Tris buffer, ultrasonically dispersed for 15-20 min, and then magnetically stirred for 20 h. The fiber is then removed, washed 3-4 times with deionized water, and dried to obtain the final product.

[0032] Example 2 A highly abrasion-resistant melamine-impregnated decorative paper, the preparation method of which is as follows: S1 Base paper pretreatment: The decorative base paper is preheated at 80℃ to a moisture content of 6.5%, and then subjected to low-temperature plasma treatment in an argon / oxygen mixed atmosphere for 2 min.

[0033] S2 Impregnated Reinforcing Layer: The modified melamine-formaldehyde resin is impregnated at a speed of 20 m / min, with an impregnation amount of 100 g / m. 2 Pre-dry at 110℃ for 30 seconds until semi-cured.

[0034] S3 interfacial bonding layer: sprayed with 1.2% KH-560 ethanol solution, spraying amount 1.5 g / m 2 .

[0035] S4 First Wear-Resistant Layer Coating Solution: 12 kg of modified nano-silica, 7 kg of polybutadiene-modified epoxy resin, and 77 kg of modified melamine-formaldehyde resin are mixed together, and 0.385 kg of ammonium polyacrylate is added. The mixture is then dispersed at high speed until uniform.

[0036] S5 Second Wear-Resistant Layer Coating Solution: 1 kg of modified basalt fiber and 2.5 kg of silicon carbide are mixed, then 8.17 kg of modified melamine-formaldehyde resin is mixed, and 0.041 kg of ammonium polyacrylate is added. The mixture is then dispersed at high speed until uniform.

[0037] S6 Third Wear-Resistant Layer Coating Solution: Mix 3 kg of waterborne polyurethane and 6 kg of modified melamine-formaldehyde resin, add 0.18 kg of modified nano-silica, and ultrasonically disperse for 22 min.

[0038] S7, Gradient Coating and Drying: Using reverse roller coating or curtain coating methods, the first abrasion-resistant layer coating liquid, the second abrasion-resistant layer coating liquid, and the third abrasion-resistant layer coating liquid are sequentially coated onto the semi-cured impregnated reinforcing decorative paper after the spraying treatment in step S3, with coating amounts of 11 g / m² respectively. 2 14 g / m 2 8 g / m 2 Pre-dry each layer at 90℃ for 45 seconds, and after the final coating, dry at 90℃ until the finished product is obtained.

[0039] The modified melamine-formaldehyde resin is prepared by the following method: A. Add 60 kg of water and 185 kg of 37% formaldehyde solution to the reactor, stir well, and adjust the pH to 8.7 with 10% NaOH solution; raise the temperature to 77℃, add 105 kg of melamine in three batches, control the temperature not to exceed 85℃, and keep the reaction at this temperature for 37 min until the solution is clear and transparent.

[0040] B. Cool the system to 72℃, then dissolve 0.2 kg of p-toluenesulfonic acid in a small amount of ethanol and add it to the system. Adjust the pH to 7.7 with 10% NaOH solution. Slowly add 12 kg of diallyl adipate dropwise over 17 min. Heat to 82℃ and react for 75 min. Add 4 kg of diethylene glycol and continue reacting for 25 min. Add 0.07 kg of hydroquinone and keep warm until the water dilution reaches 2.7. Cool to below 40℃ and adjust the pH to 8.7 with 10% NaOH solution. Discharge and set aside.

[0041] The specific preparation method of the modified nano-silica is as follows: 1) Take 100 g of nano-silica (particle size 20~30 nm), dry and pretreat at 110℃ for 3 h, and set aside for later use; 2) Dissolve 5 g of KH-560 silane coupling agent in 50 mL of ethanol / water mixed solvent (ethanol to water volume ratio of 7:1), adjust the pH to 4.5 with glacial acetic acid, and hydrolyze at room temperature for 20 min to obtain KH-560 hydrolysate; 3) Add the dried nano-silica to 1500 mL of anhydrous ethanol and ultrasonically disperse for 20 min to obtain nano-SiO2 dispersion. 4) Under stirring, the KH-560 hydrolysate was slowly added dropwise to the nano-SiO2 dispersion. After the addition was complete, the temperature was raised to 80℃ and the reaction was stirred at a constant temperature for 6 h. After the reaction was completed, the mixture was centrifuged, washed three times with anhydrous ethanol, dried under vacuum at 70℃ to constant weight, ground and sieved to obtain the final product.

[0042] The modified basalt fiber is prepared by the following method: basalt fiber desizing with acetone is added to a 3 g / L dopamine hydrochloride aqueous solution at a solid-liquid ratio of 1 g: 10 mL. The pH is then adjusted to 8.5 using 1 mol / L Tris buffer, ultrasonically dispersed for 15-20 min, and then magnetically stirred for 24 h. The fiber is then removed, washed 3-4 times with deionized water, and dried to obtain the final product.

[0043] Example 3 A highly abrasion-resistant melamine-impregnated decorative paper, the preparation method of which is as follows: S1, Pretreatment of base paper: The decorative base paper is preheated at 90°C to a moisture content of 8%, and then subjected to low-temperature plasma treatment for 3 minutes in an argon / oxygen mixed atmosphere; S2, Preparation of the impregnated reinforcing layer: The pretreated base paper is passed through the impregnation tank at a speed of 25 m / min and impregnated with modified melamine-formaldehyde resin, with the impregnation amount controlled at 120 g / m. 2 Then pre-dry at 120℃ for 20 seconds to allow the impregnated layer to reach a semi-cured state; S3, Interface Bonding Layer Spraying: Spray a 1.5% KH-560 ethanol solution onto the surface of the semi-cured impregnated reinforcing layer at a spraying rate of 2 g / m². 2 ; S4, Preparation of the first wear-resistant coating liquid: Mix 15 kg of modified nano silica, 10 kg of polybutadiene modified epoxy resin and 80 kg of modified melamine formaldehyde resin, add 0.64 kg of alkylphenol polyoxyethylene ether, and disperse evenly at high speed; S5, Preparation of the second wear-resistant coating liquid: 1 kg of modified basalt fiber and 3 kg of silicon carbide are mixed to obtain a solid mixture. The solid mixture is then mixed with 9.3 kg of modified melamine-formaldehyde resin, and 0.0744 kg of alkylphenol polyoxyethylene ether is added and dispersed evenly at high speed. S6, Preparation of the third wear-resistant layer coating liquid: Waterborne polyurethane and modified melamine-formaldehyde resin are mixed at a mass ratio of 3:7, and then 3% of modified nano-silica (based on the total mass of waterborne polyurethane and modified melamine-formaldehyde resin) is added and ultrasonically dispersed for 30 min to obtain the third wear-resistant layer coating liquid. S7, Gradient Coating and Drying: Using reverse roller coating or curtain coating methods, the first abrasion-resistant layer coating liquid, the second abrasion-resistant layer coating liquid, and the third abrasion-resistant layer coating liquid are sequentially coated onto the semi-cured impregnated reinforcing decorative paper after the spraying treatment in step S3, with coating amounts of 15 g / m² respectively. 2 18 g / m 2 12 g / m 2 Each coating layer is pre-dried at 100℃ for 30 seconds, and the final coating layer is dried directly at 100℃ to obtain the final product.

[0044] The modified melamine-formaldehyde resin is prepared by the following method: A. Add 70 kg of water and 200 kg of 37% formaldehyde solution to the reactor. After stirring, adjust the pH to 9.0 with 10% NaOH solution. After heating to 80℃, add 110 kg of melamine in three batches, controlling the temperature not to exceed 85℃. Keep the reaction at this temperature for 45 min to obtain a clear and transparent reaction solution. B. After cooling the reaction solution obtained in step A to 75°C, add 0.3 kg of p-toluenesulfonic acid dissolved in a small amount of ethanol. Adjust the pH to 8.0 with 10% NaOH solution. Slowly add 15 kg of diallyl adipate over 20 min. Then raise the temperature to 85°C and react for 90 min. Add 5 kg of diethylene glycol and continue reacting for 30 min. Add 0.1 kg of hydroquinone as a polymerization inhibitor. Keep the reaction at this temperature until the water dilution reaches 3.0, then terminate the reaction. Cool the system to below 40°C and adjust the pH to 9.0 with 10% NaOH solution before discharging.

[0045] The specific preparation method of the modified nano-silica is as follows: 1) Take 100 g of nano-silica (particle size 20~30 nm), dry and pretreat at 110℃ for 3 h, and set aside for later use; 2) Dissolve 5 g of KH-560 silane coupling agent in 50 mL of ethanol / water mixed solvent (ethanol to water volume ratio of 7:1), adjust the pH to 4.5 with glacial acetic acid, and hydrolyze at room temperature for 20 min to obtain KH-560 hydrolysate; 3) Add the dried nano-silica to 1500 mL of anhydrous ethanol and ultrasonically disperse for 20 min to obtain nano-SiO2 dispersion. 4) Under stirring, the KH-560 hydrolysate was slowly added dropwise to the nano-SiO2 dispersion. After the addition was complete, the temperature was raised to 80℃ and the reaction was stirred at a constant temperature for 6 h. After the reaction was completed, the mixture was centrifuged, washed three times with anhydrous ethanol, dried under vacuum at 70℃ to constant weight, ground and sieved to obtain KH-560 modified nano-silica.

[0046] The modified basalt fiber is prepared by the following method: basalt fiber desizing with acetone is added to a 2.5 g / L dopamine hydrochloride aqueous solution at a solid-liquid ratio of 1 g: 10 mL. The pH is then adjusted to 8.5 using 1 mol / L Tris buffer, ultrasonically dispersed for 20 min, and then magnetically stirred for 22 h. The fiber is then removed, washed 3-4 times with deionized water, and dried to obtain the final product.

[0047] Comparative Example 1 A highly wear-resistant melamine-impregnated decorative paper is prepared by a method that is basically the same as in Example 1, except that unmodified ordinary melamine-formaldehyde resin (synthesized using a conventional alkali-acid two-step method without the addition of diallyl adipate and diethylene glycol) is used in steps S2, S4, S5, and S6. The remaining operations are the same as in Example 1.

[0048] Comparative Example 2 A highly wear-resistant melamine-impregnated decorative paper is prepared using a method that is essentially the same as in Example 1, except that step S3 is omitted. Instead of spraying KH-560 ethanol solution onto the semi-cured impregnated reinforcing layer surface, the first, second, and third wear-resistant coating solutions are directly applied to the impregnated reinforcing layer surface after pre-drying in step S2. The remaining operations are the same as in Example 1.

[0049] Comparative Example 3 A highly wear-resistant melamine-impregnated decorative paper is prepared using the following method: It is essentially the same as in Example 1, except that in step S5, modified basalt fiber is not added; instead, silicon carbide and modified melamine-formaldehyde resin are mixed (the amount of silicon carbide is adjusted to be the same as the total mass of the solid mixture in Example 1, i.e., 3 kg of silicon carbide mixed with 7 kg of modified melamine-formaldehyde resin). The remaining operations are the same as in Example 1.

[0050] Comparative Example 4 A highly wear-resistant melamine-impregnated decorative paper, prepared by a method essentially the same as in Example 1, except that in step S5, silicon carbide is not added; only modified basalt fiber and modified melamine-formaldehyde resin are mixed (the amount of modified basalt fiber is adjusted to be the same as the total mass of the solid mixture in Example 1, i.e., 3 kg of modified basalt fiber and 7 kg of modified melamine-formaldehyde resin are mixed). The remaining operations are the same as in Example 1.

[0051] Comparative Example 5 A highly abrasion-resistant melamine-impregnated decorative paper is prepared using a method that is essentially the same as in Example 1, except that the basalt fibers used in step S5 are not modified with polydopamine (PDA) and only the original basalt fibers after acetone desizing are used. The remaining operations are the same as in Example 1.

[0052] Comparative Example 6 A high-wear-resistant melamine-impregnated decorative paper is prepared by the following method: basically the same as in Example 1, except that the mass ratio of modified basalt fiber to silicon carbide in step S5 is changed to 1:1 (i.e., 2 kg of modified basalt fiber, 2 kg of silicon carbide, and the total amount of solid mixture is still 4 kg). It is then mixed with modified melamine-formaldehyde resin at a ratio of solid mixture:resin = 3:7. The rest is the same as in Example 1.

[0053] Comparative Example 7 A high-wear-resistant melamine-impregnated decorative paper is prepared by the following method: basically the same as in Example 1, except that in step S5 the mass ratio of modified basalt fiber to silicon carbide is changed to 1:4 (i.e., 0.8 kg of modified basalt fiber, 3.2 kg of silicon carbide, and the total amount of solid mixture is still 4 kg), and then mixed with modified melamine-formaldehyde resin at a solid mixture:resin ratio of 3:7. The rest is the same as in Example 1.

[0054] Comparative Example 8 A highly abrasion-resistant melamine-impregnated decorative paper is prepared using a method essentially the same as in Example 1, except that in step S7, the coating order is reversed: first the third abrasion-resistant layer coating liquid is applied, then the second abrasion-resistant layer coating liquid is applied, and finally the first abrasion-resistant layer coating liquid is applied. The drying conditions after each coating remain unchanged. The remaining operations are the same as in Example 1.

[0055] Comparative Example 9 A high-wear-resistant melamine-impregnated decorative paper is prepared using the following method: It is basically the same as in Example 1, except that the three wear-resistant layers are not distinguished. Instead, the coating liquids of the first, second, and third wear-resistant layers from Example 1 are mixed evenly according to a solid-to-mass ratio (the mixing ratio is the same as the coating amount ratio of the three layers in Example 1: 8:10:5), and then coated once onto the surface of the impregnated reinforcing layer after the spraying treatment in step S3. The total coating amount is 23 g / m². 2Then pre-dry at 80°C for 30 seconds, and then dry at 80°C to the finished product. The remaining operations are the same as in Example 1.

[0056] Performance testing The decorative papers of Examples 1-3 and Comparative Examples 1-9 were tested for performance using the relevant methods in GB / T 17657-2022 "Test Methods for Physical and Chemical Properties of Wood-based Panels and Decorative Wood-based Panels". Surface abrasion resistance was expressed as abrasion loss value (g / 500r); drop ball impact resistance: a 1kg steel ball was used for drop ball impact testing, and the maximum drop height (cm) of the sample without cracking or breakage was recorded; according to Clause 4.44 of GB / T 17657-2022, crack resistance was evaluated in 5 grades; surface crack resistance was also evaluated in 5 grades. Specific test results are shown in Table 1.

[0057] Table 1 Performance Test Results As can be seen from the data in Table 1 above, Examples 1-3 of the present invention exhibit low wear values, high drop ball impact height, and optimal crack resistance and crazing resistance at level 5. This indicates that the present invention achieves comprehensive performance of high wear resistance, high impact resistance, and excellent crack resistance. This is mainly due to the present invention's synthesis of a modified melamine-formaldehyde resin with both flexibility and high reactivity through the synergistic modification of diallyl adipate and diethylene glycol. After curing, the crosslinking network is moderately loose, reducing internal stress and providing a tough matrix for the firm adhesion of the subsequent wear-resistant coating. Secondly, a composite structure of an impregnation reinforcement layer, an interface bonding layer, and a three-layer gradient wear-resistant layer is adopted: KH-560 ethanol solution is sprayed onto the surface of the semi-cured impregnation layer to construct a chemical anchoring interface; the first wear-resistant layer introduces KH-560 modified nano-silica and polybutadiene modified epoxy. The first layer consists of a resin base, forming a stress-buffered bottom layer. The second wear-resistant layer is a composite of polydopamine (PDA)-modified basalt fiber and silicon carbide in a specific ratio. The PDA coating endows the basalt fiber with abundant active functional groups, enabling it to form chemical bonds and mechanical interlocks with the resin matrix. Simultaneously, the fiber and hard silicon carbide particles synergistically construct a skeleton-hard shield network, significantly improving wear resistance. The third wear-resistant layer uses waterborne polyurethane and modified melamine-formaldehyde resin as a composite matrix, supplemented with KH-560 modified nano-silica, forming a high-hardness, dense, and scratch-resistant surface layer. The three layers are chemically bonded and transitioned with a gradient hardness, achieving a balance of rigidity and flexibility from a tough bottom layer to a rigid surface layer. This significantly improves the wear resistance of the impregnated decorative paper while maintaining good crack resistance, transparency, and hot-pressing adhesion to the board.

[0058] The results of Comparative Examples 1-9 show that the abrasion value in Comparative Example 1 is significantly higher, the drop ball impact height is drastically reduced, and the crack resistance drops to level 3. This indicates that the unmodified melamine-formaldehyde resin is brittle and has high internal stress, making it unable to form a strong bond with the wear-resistant layer, resulting in poor crack resistance. The abrasion value and drop ball impact height in Comparative Example 2 are also significantly worse than in Examples 1-3, with both crack resistance and crazing resistance at level 4. This is because the KH-560 interfacial bonding layer is crucial for the formation of the interlayer chemical bonding network; its absence weakens interlayer adhesion, reducing wear resistance and impact resistance. The results of Comparative Examples 3-5 demonstrate that the combined use of silicon carbide and modified basalt fiber in the wear-resistant coating is indispensable; neither can achieve high wear resistance and high crack resistance simultaneously when used alone. Comparative Examples 6-7 show that an excessively high proportion of modified fiber results in a relative lack of hard particles, leading to decreased wear resistance; while an insufficient proportion of modified fiber fails to effectively prevent crack propagation, increasing brittleness. The results of Comparative Example 8 show that the damage to the gradient structure leads to stress concentration, making the coating prone to cracking and resulting in overall performance degradation. Comparative Example 9 shows the worst performance in all aspects, indicating that the three-layer gradient coating of this invention is not a simple mixture, but rather achieves a comprehensive technical effect of combining rigidity and flexibility, high wear resistance, and high crack resistance through the gradual formation of a chemical bonding network and hardness gradient.

[0059] This invention achieves excellent comprehensive performance of high wear resistance, high toughness, and high transparency through the synergistic chemical bonding of modified melamine-formaldehyde resin and a three-layer gradient wear-resistant coating, especially the composite reinforcement of polydopamine-modified basalt fiber and silicon carbide. It can be widely used in high-requirement fields such as engineered wood flooring, furniture veneer panels, and cabinet panels, and has significant economic benefits and application prospects.

[0060] It should be noted that the above embodiments are merely some preferred embodiments of the present invention, and not all embodiments. Obviously, based on the above embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

Claims

1. A method for preparing highly abrasion-resistant melamine-impregnated decorative paper, characterized in that, Includes the following steps: S1, Pretreatment of base paper: The decorative base paper is preheated at 70-90℃ to a moisture content of 5%-8%, and then subjected to low-temperature plasma treatment for 1-3 minutes in an argon / oxygen mixed atmosphere. S2, Preparation of the impregnated reinforcing layer: The pretreated base paper is passed through the impregnation tank at a speed of 15-25 m / min, impregnated with modified melamine-formaldehyde resin, and the impregnation amount is controlled at 80-120 g / m. 2 Then pre-dry at 100-120℃ for 20-40 seconds to allow the impregnated layer to reach a semi-cured state. S3, Interface Bonding Layer Spraying: Spray KH-560 ethanol solution onto the surface of the semi-cured impregnated reinforcing layer, with a spraying amount of 1-2 g / m². 2 ; S4, Preparation of the first wear-resistant coating liquid: Modified nano silica, polybutadiene modified epoxy resin and modified melamine formaldehyde resin are mixed in a mass ratio, and a dispersant of 0.3%-0.8% of the mass of modified melamine formaldehyde resin is added and dispersed at high speed and uniformly. S5, Preparation of the second wear-resistant coating liquid: Modified basalt fiber and silicon carbide are mixed in a certain mass ratio to obtain a solid mixture. The solid mixture is mixed with modified melamine-formaldehyde resin in a mass ratio of 3:

7. A dispersant of 0.3%-0.8% of the mass of modified melamine-formaldehyde resin is added and dispersed at high speed for uniform dispersion. S6, Preparation of the third wear-resistant layer coating liquid: Mix waterborne polyurethane and modified melamine-formaldehyde resin at a mass ratio of 3: (5-7), then add 1%-3% of modified nano-silica, which accounts for 1%-3% of the total mass of waterborne polyurethane and modified melamine-formaldehyde resin, and ultrasonically disperse for 15-30 min to obtain the third wear-resistant layer coating liquid. S7, Gradient Coating and Drying: Using reverse roller coating or curtain coating methods, the first abrasion-resistant layer coating liquid, the second abrasion-resistant layer coating liquid, and the third abrasion-resistant layer coating liquid are sequentially coated onto the semi-cured impregnated reinforcing decorative paper after the spraying treatment in step S3, with coating amounts of 8–15 g / m² respectively. 2 10~18 g / m 2 5~12 g / m 2 After each coating layer is applied, it is pre-dried at 80–100℃ for 30–60 seconds. After the last coating layer is applied, it is directly dried at 80–100℃ to obtain the final product.

2. The method for preparing high-abrasion-resistant melamine-impregnated decorative paper according to claim 1, characterized in that, The modified melamine-formaldehyde resin is prepared by the following method: A. Add water and 37% formaldehyde solution to the reaction vessel, stir, adjust the pH to 8.5-9.0 with 10% NaOH solution, raise the temperature to 75-80℃, add melamine in three batches, control the temperature not to exceed 85℃, keep the reaction at the temperature for 30-45 minutes, and obtain a clear and transparent reaction solution. B. After cooling the reaction solution obtained in step A to 70-75℃, add p-toluenesulfonic acid dissolved in a small amount of ethanol. Adjust the pH to 7.5-8.0 with 10% NaOH solution. Slowly add diallyl adipate dropwise over 15-20 minutes. Then, raise the temperature to 80-85℃ and react for 60-90 minutes. Add diethylene glycol and continue the reaction for 20-30 minutes. Then, add hydroquinone as a polymerization inhibitor and maintain the temperature until the water dilution reaches 2.5-3.

0. Terminate the reaction and cool the system to below 40℃. Adjust the pH to 8.5-9.0 with 10% NaOH solution before discharging the product.

3. The method for preparing high-abrasion-resistant melamine-impregnated decorative paper according to claim 2, characterized in that, The modified melamine-formaldehyde resin comprises the following components by weight: 100-110 parts melamine, 170-200 parts 37% formaldehyde solution, 10-15 parts diallyl adipate, 50-70 parts water, 0.1-0.3 parts p-toluenesulfonic acid, 0.05-0.1 parts hydroquinone, and 3-5 parts diethylene glycol.

4. The method for preparing high-abrasion-resistant melamine-impregnated decorative paper according to claim 1, characterized in that, In step S3, the mass concentration of the KH-560 ethanol solution is 1-1.5%.

5. The method for preparing high-abrasion-resistant melamine-impregnated decorative paper according to claim 1, characterized in that, The mass composition of each raw material in the first wear-resistant layer coating liquid in step S4 is as follows: 10-15 parts of modified nano silica, 5-10 parts of polybutadiene-modified epoxy resin, and 75-80 parts of modified melamine-formaldehyde resin.

6. The method for preparing high-abrasion-resistant melamine-impregnated decorative paper according to claim 1, characterized in that, The modified nano-silica is nano-silica modified with silane coupling agent KH-560.

7. The method for preparing high-abrasion-resistant melamine-impregnated decorative paper according to claim 1, characterized in that, In step S5, the mass ratio of modified basalt fiber to silicon carbide is 1:(2-3).

8. The method for preparing high-abrasion-resistant melamine-impregnated decorative paper according to claim 7, characterized in that, The modified basalt fiber is prepared by the following method: basalt fiber treated with acetone desizing is added to a dopamine hydrochloride aqueous solution according to the solid-liquid ratio, then the pH is adjusted to 8.5 with 1 mol / L Tris buffer, ultrasonically dispersed for 15-20 min, and then magnetically stirred for 20-24 h. After being taken out and washed 3-4 times with deionized water, it is dried to obtain the modified basalt fiber.

9. The method for preparing high-abrasion-resistant melamine-impregnated decorative paper according to claim 7, characterized in that, The solid-liquid ratio of the basalt fiber to the dopamine hydrochloride aqueous solution is 1g:10mL; the mass concentration of the dopamine hydrochloride aqueous solution is 2-3g / L.

10. A highly abrasion-resistant melamine-impregnated decorative paper prepared by the method of any one of claims 1-9.

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