High-strength composite board containing waste clothes and preparation method of high-strength composite board

Abstract

The invention discloses a high-strength composite board containing waste clothes and a preparation method of the high-strength composite board, and relates to the technical field of composite boards. The preparation method comprises the following steps: adding ammonium polyphosphate, a high-temperature treatment clothing material and waterborne polyurethane resin into a surface layer material, uniformly mixing, pre-pressing into a sheet material, performing water-cooling shaping, and cutting to obtain a lower bottom layer; and then coating a middle layer material on the lower bottom layer and carrying out curing treatment, coating a surface layer material on the middle layer and carrying out secondary hot pressing, and cooling to obtain the high-strength composite board containing the waste clothes. According to the surface layer material, the mechanical property, the high-temperature resistance and the flame retardance of the composite board can be effectively improved by introducing the components such as the double-sided treatment clothing material and the modified treatment clothing material; the introduction of ammonium polyphosphate, high-temperature treatment clothing and other components in the lower bottom layer is combined with the specific preparation method, so that the comprehensive performance of the composite board is further improved. Therefore, the method has a wider application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of composite boards, and particularly relates to a high-strength composite board containing waste clothing and a preparation method thereof. Background Art

[0002] Tens of millions of tons of waste clothing are generated in China every year. The traditional treatment methods mainly include incineration and landfill, which not only occupy land resources and release greenhouse gases, but also may cause soil and water pollution. According to statistics, the natural degradation period of textile fibers is as long as several decades or even hundreds of years, and chemical fibers (such as polyester and nylon) are difficult to degrade, exacerbating the ecological burden. Waste clothing fibers (especially synthetic fibers such as polyester and nylon) have good tensile strength and toughness. After being compounded with substrates such as resins and adhesives, the mechanical properties of the boards can be significantly improved, meeting the requirements of the construction, packaging, automotive, furniture and other industries for lightweight and high-strength materials. At the same time, traditional composite boards relying on wood, natural fibers (such as glass fibers and carbon fibers) or petroleum-based plastics also face problems such as over-cutting of wood resources and exhaustion of fossil resources. Therefore, waste clothing can be used as a high-quality renewable reinforcing material to replace some primary resources, reduce the dependence on natural materials and petrochemical products, and alleviate the contradiction between resource supply and demand.

[0003] However, the flexural strength, impact resistance, shear resistance, high-temperature resistance and flame retardancy of the existing composite boards containing waste clothing still need to be improved. Summary of the Invention

[0004] The purpose of the present invention is to provide a high-strength composite board containing waste clothing and a preparation method thereof, and solve the following technical problems: The existing composite boards containing waste clothing still have problems such as unsatisfactory flexural strength, impact resistance, shear resistance, high-temperature resistance and flame retardancy.

[0005] The purpose of the present invention can be achieved by the following technical solutions: A preparation method of a high-strength composite board containing waste clothing includes the following steps: Step S1: Add ammonium polyphosphate, heat-treated clothing materials, and waterborne polyurethane resin to the surface material, mix well and pre-press to form a sheet with a thickness of 0.5 - 1 mm, cut it after water cooling and shaping to obtain the lower bottom layer; Step S2: Spread a 6 - 10 mm thick intermediate layer material on the lower bottom layer and cure it, and then spread a 0.5 - 1 mm thick surface material on the intermediate layer and perform secondary hot pressing, and cool to obtain a high-strength composite board containing waste clothing.

[0006] Preferably, the dosage ratio of the surface material, ammonium polyphosphate, heat-treated clothing materials, and waterborne polyurethane resin in step S1 is 80 - 100 g : 4 - 5 g : 4 - 5 g : 4 - 5 g; The temperature during the pre-pressing described in step S1 is 80-90°C, the pressure is 1-2 MPa, and the duration is 5-10 min.

[0007] Preferably, the preparation method of the surface material described in step S1 is as follows: The double-sided treated fabric is ground and then sieved, and then mixed and stirred evenly with low-density polyethylene. Then, silane coupling agent KH-550, nano-titanium dioxide, and modified treated fabric are added and mixed evenly to obtain the surface material; The dosage ratio of the double-sided treated fabric, low-density polyethylene, silane coupling agent KH-550, nano-titanium dioxide, and modified treated fabric is 180-200 g: 90-100 g: 4.5-6 g: 2.7-3 g: 9-10 g; The sieve mesh during sieving is 40-60 mesh.

[0008] Preferably, the preparation method of the high-temperature treated fabric described in step S1 is as follows: The fiber part of the waste clothing after cleaning, disinfection, and drying is carbonized at 300-400°C for 1.5-2 h in a nitrogen atmosphere, cooled and then immersed in hydrochloric acid solution. After 4-6 h, it is filtered, and then washed, dried, ground, and sieved to obtain the high-temperature treated fabric; The dosage ratio of the fiber part of the waste clothing and the hydrochloric acid solution is 500-600 g: 5-6 L; The cotton fiber content of the fiber part of the waste clothing is 5%-65%; The mass fraction of the hydrochloric acid solution is 3%-5%; The sieve mesh during sieving is 100 mesh.

[0009] Preferably, the temperature during the curing treatment described in step S2 is 115-125°C, and the curing duration is 2-2.5 h; The secondary hot pressing in step S2 is to first perform pre-pressing at 80-90°C and 0.5-1.5 MPa for 8-10 min, and then perform secondary hot pressing at 120-130°C and 7-8 MPa for 20-22 min.

[0010] Preferably, the preparation method of the intermediate layer material described in step S2 is as follows: Graphene oxide, high-temperature treated fabric, basalt fiber chopped yarn, hydroxypropyl methylcellulose, and silane coupling agent KH-550 are added to deionized water and ultrasonically dispersed. Then, it is immersed in the double-sided treated fabric and stirred and dispersed. After dehydration, glass fiber and unsaturated polyester resin are added and stirred evenly. Finally, 2-methyl ethyl ketone peroxide is added and stirred evenly to obtain the intermediate layer material; The dosage ratio of the deionized water, graphene oxide, heat-treated fabric, chopped basalt fiber, hydroxypropyl methylcellulose, silane coupling agent KH-550, double-sided treated fabric, glass fiber, unsaturated polyester resin, and 2-methyl ethyl ketone peroxide is 800-900 mL: 4-5 g: 3.2-5 g: 15-20 g: 3-4 g: 1.5-2.5 g: 200-250 g: 300-380 g: 75-95 g: 1.5-1.9 g.

[0011] Preferably, the preparation method of the modified treated fabric is as follows: Step A1: Mix choline chloride and urea, then heat with stirring to 80-100 °C, and stir at 80-100 °C for 1-2 h to obtain a deep eutectic solvent; Step A2: Immerse the double-sided treated fabric in the deep eutectic solvent and stir at 80-100 °C for 2-4 h, then add sulfamic acid and sodium bisulfate and stir and reflux at 100-130 °C for 4-6 h. After cooling to 25-30 °C, filter, wash, and dry to obtain the modified treated fabric.

[0012] Preferably, the dosage ratio of choline chloride to urea in Step A1 is 104-156 g: 120-180 g; The dosage ratio of the double-sided treated fabric, deep eutectic solvent, sulfamic acid, and sodium bisulfate in Step A2 is 20-33 g: 220-330 g: 4-10 g: 0.1-0.5 g.

[0013] Preferably, the preparation method of the double-sided treated fabric is as follows: Step B1: Add cellulase to an acetic acid-sodium acetate buffer solution with a pH of 4.7-5 and stir evenly to obtain an enzyme treatment solution; Step B2: Clean and disinfect the waste clothing fiber part, then crush it into pieces and immerse it in a sodium hydroxide solution. After soaking at 60-70 °C for 1-2 h, adjust the pH to 6.8-7.2, dehydrate and dry after 10-20 min to obtain a pretreated fabric; Step B3: Immerse the pretreated fabric in the enzyme treatment solution, treat it at 48-50 °C for 2-2.2 h, then filter, and then wash and dry to obtain an enzyme-treated fabric; Step B4: Perform plasma treatment on both sides of the enzyme-treated fabric to obtain a double-sided treated fabric.

[0014] Preferably, the dosage ratio of the acetic acid-sodium acetate buffer solution to cellulase in Step B1 is 4-5 L: 120-150 g; The dosage ratio of the waste clothing fiber part to the sodium hydroxide solution in Step B2 is 500-600 g: 4-5 L; The cotton fiber content in the waste clothing fiber part described in step B2 is 70%-100%; The mass fraction of the sodium hydroxide solution described in step B2 is 3%-5%; The size of the crushed pieces described in step B2 is 2-4 cm × 2-4 cm; The dosage ratio of the pretreated fabric to the enzyme treatment solution described in step B3 is 450-550 g: 4-5 L; During the plasma treatment described in step B4, the set nitrogen flow rate is 15 L / min, the power is 90-100 W, the plate spacing is 4-6 mm, the feeding speed is 0.5-0.6 m / min, and the treatment duration is 2.5-3 min.

[0015] As a further solution of the present invention.

[0016] Advantages of the present invention: The present invention provides a high-strength composite board containing waste clothing and a preparation method thereof. The present invention effectively improves the flexural strength, impact resistance, shear resistance, high-temperature resistance and flame retardancy of the composite board through the following methods.

[0017] (1) In the preparation process of the pretreated fabric of the present invention, the treatment with the sodium hydroxide solution will cause the cellulose to "swell", destroy its internal hydrogen bonds and crystalline structure, make the fiber volume expand, the structure loose, the crystallinity decrease, the specific surface area increase, a large number of internal hydroxyl groups are exposed, and the flexibility is improved. The swollen cellulose is more easily decomposed by cellulase, generating more terminal hydroxyl groups and reducing groups, increasing the sulfonic acid group loading amount, and further enhancing the thermal stability and flame retardancy of the composite board. Neutralizing the excessive sodium hydroxide with hydrochloric acid can avoid the inhibition of the activity of the subsequent enzyme treatment by the residual alkali; timely neutralization can also avoid the excessive hydrolysis of cellulose caused by the continuous action of the alkaline condition, and thus maintain the sufficient mechanical strength of the fiber.

[0018] (2) During the enzyme treatment process of the present invention, cellulase will make the fiber surface rough, form a microporous or grooved structure, improve the compatibility of the fiber with other components such as low-density polyethylene and unsaturated polyester resin in the composite material, reduce the interface defects, and enhance the tensile strength and flexural strength of the composite board. It will also increase the number of hydroxyl groups on the fiber surface, enhance the polarity, promote the chemical bonding of the fiber with the modifier and coupling agent, enhance the interfacial bonding between the fiber and the matrix, and reduce the interfacial debonding phenomenon of the composite material when stressed. At the same time, it can further decompose the residual cellulose derivatives or oligomers on the basis of the pretreatment, make the fiber microfibrillate, and improve the purity of the fiber.

[0019] (3) In the double-sided plasma treatment process of the present invention, nitrogen-containing polar groups such as amino groups and imino groups are introduced on both the front and back surfaces of the fabric, and nano-scale etching pits or micro-convex structures are generated, increasing the specific surface area, significantly enhancing the surface polarity and hydrophilicity, improving the interfacial compatibility with polar solvents, resins, and other fillers, promoting chemical reactions and physical adsorption, enhancing the interfacial bonding force and shear strength, reducing phase separation, thereby improving the tensile strength, impact toughness of the composite board and reducing the risk of delamination. The etching effect of the plasma can also remove pollutants such as grease, wax, or oxide layers on the fabric surface, forming a clean active surface. The active surface can also accelerate the esterification / etherification reaction of the fabric with the deep eutectic solvent and sulfamic acid, making the modification treatment more complete, forming a denser chemical cross-linking structure, and enhancing the heat resistance and mechanical properties of the material.

[0020] (4) The high-temperature treated fabric prepared by high-temperature carbonization at a specific temperature in the present invention has high hardness, rigidity, and wear resistance. When added as a filler to the lower layer and the middle layer, the high-temperature treated fabric will be evenly dispersed in waterborne polyurethane and unsaturated polyester resin, bearing part of the external load, and improving the tensile strength, bending strength, and impact resistance of the board. The microporous structure formed during the high-temperature carbonization process and the polar groups on the surface after hydrochloric acid treatment can enhance the interfacial bonding force with the resin, reduce the debonding between the filler and the matrix, and improve the interlayer shear strength. The high-temperature treated fabric can fill the inter-fiber voids of reinforcing fibers such as basalt fibers and glass fibers, forming a "fiber-carbon filler-resin" composite reinforcement system, inhibiting crack propagation, and improving the overall toughness. The high-temperature treated fabric can evenly disperse local heat, reducing the internal stress caused by uneven temperature in the board; the carbon network formed during the carbonization process has certain conductivity, which can endow the board with antistatic ability; the addition of the high-temperature treated fabric can also increase the heat distortion temperature of the composite board, reduce the dimensional change and mechanical property attenuation at high temperature, and avoid possible thermal damage during subsequent hot pressing treatment.

[0021] (5) During the preparation of the modified fabric of the present invention, the choline chloride-urea eutectic solvent can effectively break the hydrogen bond network of cotton cellulose, reduce its crystallinity, stretch the cellulose molecular chain, and expose more hydroxyl reaction sites. The sulfonic acid groups introduced by the modification treatment will generate sulfur-containing compounds such as sulfuric acid at high temperatures, promoting the dehydration and carbonization of cellulose to form a dense carbon layer, blocking the transfer of heat and oxygen, and reducing melting and dripping at the same time, thereby improving the flame retardancy grade of the composite board; during combustion, gases such as sulfur dioxide will also be released to dilute the oxygen concentration in the air and produce a phosphorus-sulfur synergistic effect with ammonium polyphosphate, forming a dual flame retardancy mechanism of "condensed-phase carbon layer + gas-phase dilution", further improving the flame retardancy ability of the composite board. The strong hydrophilicity of the sulfonic acid groups will also reduce the contact angle of the modified fabric, thereby enhancing its interfacial compatibility with polar matrices such as waterborne polyurethane, reducing interfacial defects in the composite material, and improving the interlaminar shear strength. The electron-withdrawing effect of the sulfonic acid groups will stabilize the cellulose molecular chain and delay the thermal degradation process, making the composite board have more excellent dimensional stability in a high-temperature environment.

[0022] (6) During the secondary hot pressing process of the present invention, low-density polyethylene will first be preliminarily melted at a lower temperature, form a preliminary physical bond with the lower layer and the middle layer, remove the interlayer air bubbles, and improve the interlayer fit. After rising to a higher temperature, the polyethylene will be completely melted, forming a partially interpenetrating network structure with the unsaturated polyester resin in the middle layer, significantly enhancing the interlayer bond strength and the overall structural compactness, and reducing the water absorption rate. The high-pressure condition will also promote the close contact between the modified fabric in the surface layer and the flame retardant components such as ammonium polyphosphate and high-temperature-treated fabric in the bottom layer, forming a continuous flame retardant network, improving the dispersion uniformity of the flame retardant and the synergistic flame retardant effect. The lateral vibration cooling at a specific frequency will promote the uniform distribution of the internal thermal stress of the material, reduce the internal stress concentration caused by uneven shrinkage during the cooling process, reduce the risk of cracking, improve the dimensional stability and impact toughness; at the same time, make the molten resin and filler flow further, fill the micropores, optimize the internal fiber orientation of the material, form a more uniform multi-scale composite structure, and enhance the uniformity of the mechanical properties and flame retardancy.

[0023] Therefore, the high-strength composite board containing waste clothes prepared by the present invention has more excellent flexural strength, impact resistance, shear resistance, high-temperature resistance and flame retardancy, as well as a more extensive application prospect. Specific Embodiments

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present invention.

[0025] The sources and properties of some raw materials of the present invention are as follows: Cellulase was purchased from Shaanxi Runfeng Biotechnology Co., Ltd., CAS: 9012-54-8; chopped basalt fiber yarn was purchased from Shandong Oude Chemical Fiber Products Co., Ltd.; nano-titanium dioxide (particle size 25 nm) was purchased from Shanghai Jiadeer Chemical Technology Co., Ltd., CAS: 13463-67-7; waterborne polyurethane resin was purchased from Nantong Runfeng Petrochemical Co., Ltd.; graphene oxide was purchased from Shanghai Xiaohuang Nano Technology Co., Ltd., CAS: 1034343-98-0; unsaturated polyester resin was purchased from Hubei Baidu Chemical Co., Ltd., CAS: 26098-37-3.

[0026] Example 1: A preparation method of a high-strength composite board containing waste clothes is as follows: S1: Add 120 g of cellulase to 4 L of acetic acid-sodium acetate buffer solution with a pH of 4.7, and stir evenly to obtain an enzyme treatment solution; S2: Stir and wash the fiber part of 500 g of waste clothes with a cotton fiber content of 70% in 5 L of deionized water at 40 °C for 20 min, then rinse 3 times with clean water, then soak and disinfect in 5 L of sodium hypochlorite solution with a mass fraction of 0.1% for 15 min, then crush into 2 cm × 2 cm pieces and immerse in 4 L of sodium hydroxide solution with a mass fraction of 3%. After soaking at 60 °C for 1 h, adjust the pH to 6.8 with hydrochloric acid solution with a mass fraction of 2%. After 10 min, dehydrate and dry to obtain pretreated fabric; S3: Immerse 450 g of pretreated fabric in 4 L of enzyme treatment solution, treat at 48 °C at 100 r / min for 2 h, then filter, rinse 3 times with deionized water, and finally dry at 80 °C and -0.08 MPa to obtain enzyme-treated fabric; S4: Perform plasma treatment on both sides of 400 g of enzyme-treated fabric with a nitrogen flow rate of 15 L / min, a power of 90 W, a plate distance of 4 mm, a feeding speed of 0.5 m / min, and a treatment duration of 2.5 min to obtain double-sided treated fabric; S5: Heat the fiber part of 500 g of waste clothes with a cotton fiber content of 5% after cleaning, disinfection and drying from room temperature to 300 °C at a heating rate of 5 °C / min in a nitrogen atmosphere, carbonize at 300 °C for 1.5 h, cool to 25 °C, immerse in 5 L of hydrochloric acid solution with a mass fraction of 3%, filter after 4 h, rinse 3 times with deionized water, and finally dry at 95 °C, grind and pass through a 100-mesh sieve to obtain high-temperature treated fabric; S6: Mix 104 g of choline chloride and 120 g of urea, then stir at 200 r / min and heat to 80 °C at a rate of 10 °C / min, and then stir at 80 °C for 1 h to obtain a deep eutectic solvent; S7: Immerse 20 g of double-sided treated fabric in 220 g of eutectic solvent, stir at 100 r / min at 80 °C for 2 h, then add 4 g of sulfamic acid and 0.1 g of sodium bisulfate, stir and reflux at 200 r / min at 100 °C for 4 h. After cooling to 25 °C, filter, wash with deionized water 5 times, and dry at 60 °C to obtain the modified treated fabric; S8: Grind 180 g of double-sided treated fabric and pass through a 40-mesh sieve, then mix with 90 g of low-density polyethylene and stir at 600 r / min for 5 min. Then add 4.5 g of silane coupling agent KH-550, 2.7 g of nano-titanium dioxide, and 9 g of modified treated fabric, and finally mix at 1500 r / min for 15 min to obtain the surface material; S9: Add 4 g of ammonium polyphosphate, 4 g of high-temperature treated fabric, and 4 g of waterborne polyurethane resin to 80 g of surface material, then mix at 1400 r / min for 15 min, and then pre-press at 80 °C and 1 MPa for 5 min to make a 0.5-mm sheet. After water cooling and shaping, cut into 50 cm × 50 cm to obtain the lower bottom layer; S10: Add 4 g of graphene oxide, 3.2 g of high-temperature treated fabric, 15 g of chopped basalt fiber, 3 g of hydroxypropyl methylcellulose, and 1.5 g of silane coupling agent KH-550 to 800 mL of deionized water, then perform ultrasonic dispersion at a frequency of 38 kHz for 20 min, then immerse 200 g of double-sided treated fabric and stir at 180 r / min for 1 h. After dehydration, add 300 g of glass fiber and 75 g of unsaturated polyester resin and stir at 400 r / min for 10 min. Finally, add 1.5 g of 2-butyl peroxide and continue to stir for 4 min to obtain the intermediate layer material; S11: Coat 6 mm thick of the intermediate layer material on the lower bottom layer and cure at 115 °C for 2 h. Then coat 0.5 mm thick of the surface material on the intermediate layer, first pre-press at 80 °C and 0.5 MPa for 8 min, then perform secondary hot pressing at 120 °C and 7 MPa for 20 min, and finally cool naturally to 25 °C while vibrating horizontally at a frequency of 50 Hz to obtain the high-strength composite board containing waste clothing.

[0027] Example 2: A method for preparing a high-strength composite board containing waste clothing is as follows: S1: Add 135 g of cellulase to 4.5 L of acetic acid-sodium acetate buffer solution with a pH of 4.8, stir evenly to obtain the enzyme treatment solution; S2: Stir and wash the 550 g of waste clothing fibers with 85% cotton fiber content in 5.5 L of deionized water at 450 °C for 25 min, then rinse with clean water 4 times. After that, soak and disinfect in 5.5 L of sodium hypochlorite solution with a mass fraction of 0.15% for 18 min, then crush into 3 cm × 3 cm pieces and immerse in 4.5 L of sodium hydroxide solution with a mass fraction of 4%. After soaking at 65 °C for 1.5 h, adjust the pH to 7 with a hydrochloric acid solution with a mass fraction of 2.5%. After 15 min, dehydrate and dry to obtain the pretreated fabric; S3: Immerse 500 g of the pretreated fabric in 4.5 L of enzyme treatment solution, treat at 49 °C at 120 r / min for 2.1 h, then filter, rinse with deionized water 4 times, and finally dry at 83 °C and -0.09 MPa to obtain the enzyme-treated fabric; S4: Perform plasma treatment on both sides of 450 g of the enzyme-treated fabric with a nitrogen flow rate of 15 L / min, a power of 95 W, a plate spacing of 5 mm, a feeding speed of 0.55 m / min, and a treatment duration of 2.7 min to obtain the double-sided treated fabric; S5: Under a nitrogen atmosphere, heat the 550 g of waste clothing fibers with 35% cotton fiber content after cleaning, disinfecting, and drying from room temperature to 350 °C at a heating rate of 7 °C / min, and carbonize at 350 °C for 1.7 h. After cooling to 27 °C, immerse in 5.5 L of hydrochloric acid solution with a mass fraction of 4%. After 5 h, filter, rinse with deionized water 4 times, and finally dry at 98 °C, grind, and pass through a 100-mesh sieve to obtain the high-temperature treated fabric; S6: Mix 130 g of choline chloride and 150 g of urea, then stir at 250 r / min and heat to 90 °C at a rate of 15 °C / min, and then stir at 90 °C for 1.5 h to obtain the deep eutectic solvent; S7: Immerse 26 g of the double-sided treated fabric in 260 g of the deep eutectic solvent and stir at 90 °C at 150 r / min for 3 h. Then add 7 g of sulfamic acid and 0.3 g of sodium bisulfate and stir and reflux at 120 °C at 250 r / min for 5 h. After cooling to 28 °C, filter, wash with deionized water 6 times, and dry at 70 °C to obtain the modified treated fabric; S8: Grind 190 g of the double-sided treated fabric and pass through a 50-mesh sieve, then mix with 95 g of low-density polyethylene and stir at 700 r / min for 8 min. Then add 5 g of silane coupling agent KH-550, 2.8 g of nano-titanium dioxide, and 9.5 g of the modified treated fabric, and finally mix at 1500 r / min for 17 min to obtain the surface material; S9: Add 4.5 g of ammonium polyphosphate, 4.5 g of heat-treated fabric, and 4.5 g of waterborne polyurethane resin to 90 g of surface material, then mix at 1450 r / min for 17 min, and then pre-press at 85 °C and 1.5 MPa for 8 min to make a 0.8-mm sheet. After water cooling and shaping, cut it into 50 cm × 50 cm to obtain the lower bottom layer; S10: Add 4.5 g of graphene oxide, 4.1 g of heat-treated fabric, 17.5 g of chopped basalt fiber yarn, 3.5 g of hydroxypropyl methylcellulose, and 2 g of silane coupling agent KH-550 to 850 mL of deionized water. Then perform ultrasonic dispersion for 25 min at a frequency of 39 kHz, then immerse it in 225 g of double-sided treated fabric and stir at 190 r / min for 1.3 h. After dehydration, add 340 g of glass fiber and 85 g of unsaturated polyester resin and stir at 400 r / min for 13 min. Finally, add 1.7 g of 2-butyl peroxide and continue to stir for 5 min to obtain the intermediate layer material; S11: Spread 8-mm-thick intermediate layer material on the lower bottom layer and cure at 120 °C for 2.3 h. Then spread 0.7-mm-thick surface material on the intermediate layer and first perform pre-pressing at 85 °C and 1 MPa for 9 min, and then perform secondary hot pressing at 125 °C and 7.5 MPa for 21 min. Finally, cool naturally to 28 °C while vibrating horizontally at a frequency of 50 Hz to obtain a high-strength composite board containing waste clothing;

[0028] Example 3: A method for preparing a high-strength composite board containing waste clothing is as follows: S1: Add 150 g of cellulase to 5 L of acetic acid-sodium acetate buffer solution with a pH of 5 and stir evenly to obtain an enzyme treatment solution; S2: Stir and wash the fiber part of 600 g of waste clothing with 100% cotton fiber content in 6 L of deionized water at 50 °C for 30 min, then rinse with clean water 5 times, and then soak and disinfect in 6 L of sodium hypochlorite solution with a mass fraction of 0.2% for 20 min. Then crush it into 4 cm × 4 cm pieces and immerse it in 5 L of sodium hydroxide solution with a mass fraction of 5%. After soaking at 70 °C for 2 h, adjust the pH to 7.2 with hydrochloric acid solution with a mass fraction of 3%. After 20 min, dehydrate and dry to obtain the pretreated fabric; S3: Immerse 550 g of pretreated fabric in 5 L of enzyme treatment solution, treat it at 50 °C at 140 r / min for 2.2 h, then filter, rinse with deionized water 5 times, and finally dry at 85 °C and -0.1 MPa to obtain the enzyme-treated fabric; S4: Perform plasma treatment on both sides of 500 g of enzyme-treated fabric with a nitrogen flow rate of 15 L / min, a power of 100 W, a plate spacing of 6 mm, a feeding speed of 0.6 m / min, and a treatment duration of 3 min to obtain double-sided treated fabric; S5: Under a nitrogen atmosphere, heat the 600 g of waste clothing fibers with a cotton fiber content of 65% after cleaning, disinfection, and drying from room temperature to 400 °C at a heating rate of 10 °C / min, carbonize at 400 °C for 2 h, cool to 30 °C, immerse in 6 L of a 5% hydrochloric acid solution, filter after 6 h, rinse with deionized water 5 times, and finally dry at 100 °C, grind, and pass through a 100-mesh sieve to obtain the high-temperature-treated fabric; S6: Mix 156 g of choline chloride and 180 g of urea, then heat to 100 °C at a rate of 20 °C / min while stirring at 300 r / min, and then stir at 100 °C for 2 h to obtain the deep eutectic solvent; S7: Immerse 33 g of the double-sided treated fabric in 330 g of the deep eutectic solvent, stir at 200 r / min at 100 °C for 4 h, then add 10 g of sulfamic acid and 0.5 g of sodium bisulfate, stir and reflux at 300 r / min at 130 °C for 6 h, filter after cooling to 30 °C, wash with deionized water 7 times, and dry at 80 °C to obtain the modified treated fabric; S8: Grind 200 g of the double-sided treated fabric and pass through a 60-mesh sieve, then mix with 100 g of low-density polyethylene and stir at 800 r / min for 10 min, add 6 g of silane coupling agent KH-550, 3 g of nano-titanium dioxide, and 10 g of the modified treated fabric, and finally mix at 1500 r / min for 20 min to obtain the surface material; S9: Add 5 g of ammonium polyphosphate, 5 g of the high-temperature-treated fabric, and 5 g of waterborne polyurethane resin to 100 g of the surface material, then mix at 1500 r / min for 20 min, pre-press at 90 °C and 2 MPa for 10 min to form a 1-mm sheet, cool and shape with water, and cut into 50 cm × 50 cm to obtain the lower bottom layer; S10: Add 5 g of graphene oxide, 5 g of the high-temperature-treated fabric, 20 g of chopped basalt fibers, 4 g of hydroxypropyl methylcellulose, and 2.5 g of silane coupling agent KH-550 to 900 mL of deionized water, then perform ultrasonic dispersion at a frequency of 40 kHz for 30 min, immerse 250 g of the double-sided treated fabric, stir at 200 r / min for 1.5 h, dehydrate, add 380 g of glass fibers and 95 g of unsaturated polyester resin, stir at 400 r / min for 15 min, and finally add 1.9 g of 2-butanone peroxide and continue stirring for 6 min to obtain the intermediate layer material; S11: Apply an intermediate layer material with a thickness of 10 mm on the lower bottom layer and cure it at 125 °C for 2.5 h. Then, apply a surface layer material with a thickness of 1 mm on the intermediate layer. First, perform a pre-pressing at 90 °C and 1.5 MPa for 10 min, and then perform a secondary hot pressing at 130 °C and 8 MPa for 22 min. Finally, cool it naturally to 30 °C while vibrating horizontally at a frequency of 50 Hz to obtain a high-strength composite board containing waste clothing.

[0029] Comparative Example 1: Compared with Example 1, in this comparative example, only the preparation process of the pretreated clothing material in S2 is changed. Replace "Stir and wash 500 g of waste clothing fibers with a cotton fiber content of 70% in 5 L of deionized water at 40 °C for 20 min, then rinse with clean water 3 times, then soak and disinfect in 5 L of sodium hypochlorite solution with a mass fraction of 0.1% for 15 min, then crush into 2 cm × 2 cm pieces and immerse in 4 L of sodium hydroxide solution with a mass fraction of 3%. After soaking at 60 °C for 1 h, adjust the pH to 6.8 with hydrochloric acid solution with a mass fraction of 2%, and dehydrate and dry after 10 min" with "Stir and wash 500 g of waste clothing fibers with a cotton fiber content of 70% in 5 L of deionized water at 40 °C for 20 min, then rinse with clean water 3 times, then soak and disinfect in 5 L of sodium hypochlorite solution with a mass fraction of 0.1% for 15 min, then dehydrate and dry". The remaining steps and parameters are the same, and this comparative example will not be repeated. Finally, a high-strength composite board containing waste clothing is obtained.

[0030] Comparative Example 2: Compared with Example 1, in this comparative example, only the "enzymatically treated clothing material" used in the preparation process of the double-sided treated clothing material in S4 is replaced with the "pretreated clothing material" prepared in S2. The remaining steps and parameters are the same, and this comparative example will not be repeated. Finally, a high-strength composite board containing waste clothing is obtained.

[0031] Comparative Example 3: Compared with Example 1, in this comparative example, only the "heating from room temperature to 300 °C at a heating rate of 5 °C / min and carbonizing at 300 °C for 1.5 h" in the preparation process of the high-temperature treated clothing material in S5 is replaced with "heating from room temperature to 120 °C at a heating rate of 5 °C / min and carbonizing at 120 °C for 1.5 h". The remaining steps and parameters are the same, and this comparative example will not be repeated. Finally, a high-strength composite board containing waste clothing is obtained.

[0032] Comparative Example 4: Compared with Example 1, in this comparative example, only the "double-sided treated clothing material" used in the preparation process of the modified treated clothing material in S7 is replaced with the "enzymatically treated clothing material" prepared in S3. The remaining steps and parameters are the same, and this comparative example will not be repeated. Finally, a high-strength composite board containing waste clothing is obtained.

[0033] Comparative Example 5: Compared with Example 1, in this comparative example, only the step of "immersing 20 g of double-sided treated fabric into 220 g of eutectic solvent and stirring at 100 r / min for 2 h at 80°C, then adding 4 g of sulfamic acid and 0.1 g of sodium bisulfate and stirring and refluxing at 200 r / min for 4 h at 100°C" in the preparation process of the modified treated fabric of S7 was replaced with "immersing 20 g of double-sided treated fabric into 220 g of deionized water, then adding 4 g of sulfamic acid and 0.1 g of sodium bisulfate and stirring and refluxing at 200 r / min for 4 h at 100°C", and the rest of the steps and parameters were the same. This comparative example will not be repeated here. Finally, a high-strength composite board containing waste clothing was obtained.

[0034] Comparative Example 6: Compared with Example 1, in this comparative example, only "9 g of modified treated fabric" was not added in the preparation process of the surface material of S8, and the rest of the steps and parameters were the same. This comparative example will not be repeated here. Finally, a high-strength composite board containing waste clothing was obtained.

[0035] Comparative Example 7: Compared with Example 1, in this comparative example, only the "4 g of high-temperature treated fabric" added in the preparation process of the lower bottom layer of S9 was replaced with "4 g of ammonium polyphosphate", and the rest of the steps and parameters were the same. This comparative example will not be repeated here. Finally, a high-strength composite board containing waste clothing was obtained.

[0036] Comparative Example 8: Compared with Example 1, in this comparative example, only "3.2 g of high-temperature treated fabric" was not added in the preparation process of the intermediate layer material of S10, and the rest of the steps and parameters were the same. This comparative example will not be repeated here. Finally, a high-strength composite board containing waste clothing was obtained.

[0037] Comparative Example 9: Compared with Example 1, in this comparative example, only the steps of "pre-pressing at 80°C and 0.5 MPa for 8 min, and then secondary hot-pressing at 120°C and 7 MPa for 20 min" in the preparation process of the high-strength composite board containing waste clothing of S11 were replaced with "hot-pressing at 120°C and 7 MPa for 28 min", and the rest of the steps and parameters were the same. This comparative example will not be repeated here. Finally, a high-strength composite board containing waste clothing was obtained.

[0038] Comparative Example 10: Compared with Example 1, in this comparative example, only the step of "naturally cooling to 25°C while vibrating horizontally at a frequency of 50 Hz" in the preparation process of the high-strength composite board containing waste clothing of S11 was replaced with "naturally cooling to 25°C", and the rest of the steps and parameters were the same. This comparative example will not be repeated here. Finally, a high-strength composite board containing waste clothing was obtained.

[0039] Performance detection: Determination of flexural strength: Referring to the standard of GB / T 9341-2008 "Plastics - Determination of flexural properties", with a span of 64h (h is the specimen thickness) and a loading speed of 2mm / min, the flexural strength (MPa) of the high-strength composite boards containing waste clothing prepared in Examples 1-3 and Comparative Examples 1-10 of the present invention before and after 10008h of damp heat cycle (the cycle process is to store at 70°C and 95% PH for 8h first, and then store at 25°C and 95% PH for 16h, and cycle 42 times according to this) was determined. The test results are shown in Table 1.

[0040] Determination of impact strength: Referring to the standard of GB / T 1043.1-2023 "Plastics - Determination of Charpy impact properties - Part 1: Non-instrumented impact test", with an impact speed of 3.8m / s, the impact strength (KJ / m -2 ) of the high-strength composite boards containing waste clothing prepared in Examples 1-3 and Comparative Examples 1-10 of the present invention was determined. The test results are shown in Table 1 Determination of shear strength: Referring to the standard of ASTM D2344 "Standard test method for short-beam shear strength of polymer matrix composites", with a span of 5h (h is the specimen thickness) and a loading speed of 1mm / min, the shear strength (MPa) of the high-strength composite boards containing waste clothing prepared in Examples 1-3 and Comparative Examples 1-10 of the present invention was determined. The test results are shown in Table 1.

[0041] Determination of high-temperature resistance: The composite board was cut into rectangular specimens of 150mm×100mm, placed in an environment of 25°C and relative humidity of 50% for 24h, and the initial length, width and thickness of the specimens were measured. Then the specimens were placed horizontally on the quartz platform in a high-temperature constant-temperature oven, avoiding stress or stacking, and heated to 200°C at a heating rate of 5°C / min. After holding for 2h, the constant-temperature oven was closed, and the specimens were allowed to cool naturally in the oven to 25°C. The length, width and thickness of the specimens were measured again and the change rates of the length, width and thickness of the specimens were calculated. The total change rate after adding the change rates of the length, width and thickness was used as the high-temperature resistance of the composite board cut. The smaller the total change rate, the better the high-temperature resistance of the composite board cut. According to the above method, the high-temperature resistance (%) of the high-strength composite boards containing waste clothing prepared in Examples 1-3 and Comparative Examples 1-10 of the present invention was determined. The test results are shown in Table 1.

[0042] Determination of flame retardancy: Refer to the standard of GB / T 2408-2021 "Plastics - Determination of burning behaviour - Horizontal and vertical methods", cut the composite board into specimens of 127 mm × 13 mm, fix them vertically, and keep the lower end 10 mm away from the methane flame of the burning lamp. After igniting the specimen for 10 s, remove the flame and record: the first burning time (t1, the time when the flame goes out); if there are dripping substances, observe whether the absorbent cotton is ignited; ignite again for 10 s and record the second burning time (t2). Then, judge the flame retardant grade of the composite board according to this grading standard (V-0 grade: t1 ≤ 10 s, t2 ≤ 30 s, no dripping ignition; V-1 grade: t1 ≤ 30 s, t2 ≤ 60 s, no dripping ignition; V-2 grade: dripping ignition of absorbent cotton is allowed, and the rest is the same as V-1). Determine the flame retardant ability (grade) of the high-strength composite boards containing waste clothes prepared in Examples 1 - 3 and Comparative Examples 1 - 10 of the present invention according to the above method, and the test results are shown in Table 1.

[0043] Table 1: Performance test results of Examples 1 - 3 and Comparative Examples 1 - 10 ; Data analysis: As can be seen from Table 1, the high-strength composite boards containing waste clothes prepared by the present invention have excellent bending strength, resistance to humidity and heat, impact resistance, shear resistance, high temperature resistance and flame retardant ability.

[0044] The above has described a specific embodiment of the present invention in detail, but the described content is only the preferred embodiment of the present invention and cannot be considered as limiting the scope of implementation of the present invention. Any equivalent changes and improvements made within the scope of the application of the present invention shall still fall within the scope covered by the patent of the present invention.

Claims

1. A preparation method of a high-strength composite board containing waste clothing, characterized in that, It includes the following steps: Step S1: Add ammonium polyphosphate, heat-treated fabric, and waterborne polyurethane resin to the surface material. After mixing evenly, pre-press it into a sheet, cut it after water cooling and shaping, and obtain the lower bottom layer; Step S2: Coat the intermediate layer material on the lower bottom layer and cure it. Then coat the surface material on the intermediate layer and perform secondary hot pressing. After cooling, obtain a high-strength composite board containing waste clothing.

2. The preparation method of the high-strength composite board containing waste clothes according to claim 1, characterized in that, In Step S1, the dosage ratio of the surface material, ammonium polyphosphate, heat-treated fabric, and waterborne polyurethane resin is 80-100 g: 4-5 g: 4-5 g: 4-5 g; In Step S1, the temperature during pre-pressing is 80-90 °C, the pressure is 1-2 MPa, and the duration is 5-10 min.

3. The preparation method of the high-strength composite board containing waste clothes according to claim 1, characterized in that, The preparation method of the surface material in Step S1 is as follows: Grind the double-sided treated fabric and sieve it. Then mix it with low-density polyethylene and stir evenly. Add silane coupling agent KH-550, nano-titanium dioxide, and modified treated fabric, and mix evenly to obtain the surface material; The dosage ratio of the double-sided treated fabric, low-density polyethylene, silane coupling agent KH-550, nano-titanium dioxide, and modified treated fabric is 180-200 g: 90-100 g: 4.5-6 g: 2.7-3 g: 9-10 g.

4. The preparation method of the high-strength composite board containing waste clothing according to claim 1, wherein, The preparation method of the heat-treated fabric in Step S1 is as follows: Carbonize the fiber part of the waste clothing after cleaning, disinfecting, and drying in a nitrogen atmosphere at 300-400 °C for 1.5-2 h. After cooling, immerse it in hydrochloric acid solution. After 4-6 h, filter it, and then perform washing, drying, grinding, and sieving to obtain the heat-treated fabric; The dosage ratio of the fiber part of the waste clothing and the hydrochloric acid solution is 500-600 g: 5-6 L; The cotton fiber content of the fiber part of the waste clothing is 5%-65%; The mass fraction of the hydrochloric acid solution is 3%-5%.

5. The preparation method of the high-strength composite board containing waste clothes according to claim 1, characterized in that, In Step S2, the secondary hot pressing is to first perform pre-pressing at 80-90 °C and 0.5-1.5 MPa for 8-10 min, and then perform secondary hot pressing at 120-130 °C and 7-8 MPa for 20-22 min.

6. The preparation method of the high-strength composite board containing waste clothes according to claim 1, characterized in that, The preparation method of the intermediate layer material in Step S2 is as follows: Add graphene oxide, heat-treated fabric, chopped basalt fiber yarn, hydroxypropyl methylcellulose, and silane coupling agent KH-550 to deionized water and perform ultrasonic dispersion. Then immerse it in the double-sided treated fabric and stir to disperse. After dehydration, add glass fiber and unsaturated polyester resin and stir evenly. Finally, add 2-methyl ethyl ketone peroxide and stir evenly to obtain the intermediate layer material; The dosage ratio of deionized water, graphene oxide, heat-treated fabric, chopped basalt fiber yarn, hydroxypropyl methylcellulose, silane coupling agent KH-550, double-sided treated fabric, glass fiber, unsaturated polyester resin, and 2-methyl ethyl ketone peroxide is 800-900 mL: 4-5 g: 3.2-5 g: 15-20 g: 3-4 g: 1.5-2.5 g: 200-250 g: 300-380 g: 75-95 g: 1.5-1.9 g.

7. The preparation method of the high-strength composite board containing waste clothes according to claim 3, characterized in that, The preparation method of the modified treated fabric is as follows: Step A1: Mix choline chloride and urea, then heat to 80 - 100 °C with stirring, and then stir at 80 - 100 °C for 1 - 2 h to obtain a deep eutectic solvent; Step A2: Immerse the double-sided treated fabric into the deep eutectic solvent and stir at 80 - 100 °C for 2 - 4 h. Then add sulfamic acid and sodium bisulfate and stir and reflux at 100 - 130 °C for 4 - 6 h. After cooling to 25 - 30 °C, filter, wash, and dry to obtain the modified treated fabric.

8. The preparation method of the high-strength composite board containing waste clothes according to claim 7, characterized in that, In Step A1, the dosage ratio of the choline chloride to the urea is 104 - 156 g: 120 - 180 g; In Step A2, the dosage ratio of the double-sided treated fabric, the deep eutectic solvent, sulfamic acid, and sodium bisulfate is 20 - 33 g: 220 - 330 g: 4 - 10 g: 0.1 - 0.5 g.

9. The preparation method of the high-strength composite board containing waste clothing according to claim 3, characterized in that, The preparation method of the double-sided treated fabric is as follows: Step B1: Add cellulase to an acetic acid - sodium acetate buffer solution with a pH of 4.7 - 5 and stir evenly to obtain an enzyme treatment solution; Step B2: Clean and disinfect the fiber part of waste clothing, then crush it into pieces and immerse it in a sodium hydroxide solution. After soaking at 60 - 70 °C for 1 - 2 h, adjust the pH to 6.8 - 7.2, dehydrate and dry after 10 - 20 min to obtain a pretreated fabric; Step B3: Immerse the pretreated fabric into the enzyme treatment solution, filter after treating at 48 - 50 °C for 2 - 2.2 h, and then perform washing and drying treatments to obtain an enzyme-treated fabric; Step B4: Perform plasma treatment on both sides of the enzyme-treated fabric to obtain a double-sided treated fabric.

10. The preparation method of the high-strength composite board containing waste clothes according to claim 9, characterized in that, In Step B1, the dosage ratio of the acetic acid - sodium acetate buffer solution to the cellulase is 4 - 5 L: 120 - 150 g; In Step B2, the dosage ratio of the fiber part of waste clothing to the sodium hydroxide solution is 500 - 600 g: 4 - 5 L; In Step B2, the cotton fiber content in the fiber part of waste clothing is 70% - 100%; In Step B2, the mass fraction of the sodium hydroxide solution is 3% - 5%; In Step B3, the dosage ratio of the pretreated fabric to the enzyme treatment solution is 450 - 550 g: 4 - 5 L; In Step B4, when performing plasma treatment, the set nitrogen flow rate is 15 L / min, the power is 90 - 100 W, the plate distance is 4 - 6 mm, the feeding speed is 0.5 - 0.6 m / min, and the treatment duration is 2.5 - 3 min.