Composite board based on retired wind power blade and preparation method of composite board

Abstract

The invention relates to the technical field of solid waste treatment and home decoration building material manufacturing, in particular to a composite board based on an out-of-service wind power blade and a preparation method of the composite board, and the composite board is prepared from the following raw materials in parts by weight through cold pressing and curing: 40-60 parts of a base material, 40-60 parts of an adhesive material and 10-20 parts of a functional additive, the base material comprises physically crushed materials of the retired wind turbine blade, biomass fibers and milky white rubber powder; the adhesive material is an aqueous solution mixture containing magnesium oxide, magnesium chloride, magnesium sulfate and a retarder as media. According to the invention, the retired wind power blade is directly physically crushed and then is used as a main base material, so that all complex components such as glass fiber, resin and cork wood in the retired wind power blade are directly utilized. Compared with a complex and high-cost process for separating the glass fibers through chemical degradation, the method has the advantages that the recovery cost and the energy consumption are greatly reduced, and secondary pollution caused by chemical degradation is also avoided.

Description

Technical Field

[0001] This invention relates to the fields of solid waste treatment and home decoration building materials manufacturing technology, and in particular to a composite board based on retired wind turbine blades and its preparation method. Background Technology

[0002] Since the 1990s, the wind power industry has entered a stage of large-scale development. Early installed wind turbine units have now reached their design life of 20-25 years, resulting in a large number of retired wind turbine blades that urgently need to be disposed of. Wind turbine blades are mainly made of glass fiber reinforced thermosetting resin matrix composite materials, which are extremely chemically stable and difficult to degrade naturally. If traditional methods such as landfill or incineration are used for disposal, it will cause serious environmental pollution and waste of resources.

[0003] Currently, the recycling methods for retired wind turbine blades mainly include whole-body utilization, mechanical recycling, heat recovery, chemical recovery, and energy recovery. Among these, mechanical recycling, which processes the blades into block or powder materials through physical methods such as cutting and crushing, has the advantages of simple process, large processing capacity, and relatively low cost, and is considered one of the ideal directions for achieving large-scale harmless and resource-based treatment of retired blades. However, the blade shredded material recovered by this method is a complex heterogeneous mixture containing various components such as glass fiber, resin, and balsa wood. Its surface inertness and uneven composition result in poor interfacial bonding with the matrix material. When directly used to prepare composite materials, the products often have defects such as poor mechanical properties and poor dimensional stability, resulting in very low use value and economic efficiency. This greatly limits the high-value application of mechanical recycling.

[0004] To enhance the value of recycled products, existing technologies have shifted towards more complex solutions. For example, Chinese invention patent CN119613858A discloses a high-performance composite board made from waste wind turbine blades. This technical solution abandons the simple approach of directly utilizing mechanically crushed materials. Instead, it requires first separating recycled glass fibers from waste wind turbine blades through chemical degradation. Then, the resulting "waste wind turbine blade powder" and "degraded glass fibers from waste wind turbine blades" are used as reinforcing materials, mixed with thermoplastic resins (such as polypropylene and polyethylene) and various additives through high-temperature melt mixing and extrusion to prepare the board. Although this solution can improve the performance of the board to some extent, it has the following unavoidable problems: the chemical degradation process itself is energy-intensive, involves the use of chemicals, and generates new waste liquid, deviating from the original intention of green environmental protection; the entire preparation process relies on high-temperature (usually exceeding 150°C) mixing and extrusion, resulting in high production costs; the product is essentially still in the category of wood-plastic composite materials, failing to overcome the inherent deficiencies of thermoplastic materials in terms of weather resistance, creep resistance, and long-term dimensional stability, and there is a risk of releasing volatile organic compounds during the production process.

[0005] At the same time, the construction and home decoration industries have an increasingly urgent need for high-performance composite boards that are low-cost, lightweight, high-strength, green, environmentally friendly, and formaldehyde-free.

[0006] Therefore, there is an urgent need in this field for a novel technological approach that can both directly and efficiently utilize mechanically pulverized materials from retired wind turbine blades, and produce high-performance boards with superior properties that meet the requirements of building and home decoration through a low-energy, environmentally friendly process. This would effectively solve the problem of poor interfacial compatibility of mechanically recycled materials, while avoiding the high costs and environmental pressures of high-temperature thermoplastic processes.

[0007] In view of this, the present invention is proposed. Summary of the Invention

[0008] The purpose of this invention is to provide a composite material based on retired wind turbine blades and its preparation method. This composite material is characterized by being green, environmentally friendly, and easy to industrialize.

[0009] In a first aspect, the present invention provides a composite material based on retired wind turbine blades, which is made by cold pressing and curing raw materials comprising the following parts by weight: 40-60 parts of matrix material, 40-60 parts of adhesive material, and 10-20 parts of functional additives. The matrix material includes physically crushed material of decommissioned wind turbine blades, biomass fiber, and white glue powder; The adhesive material is an aqueous mixture comprising magnesium oxide, magnesium chloride, magnesium sulfate, and a retarder as media.

[0010] In this invention, firstly, the composite board based on decommissioned wind turbine blades is made by cold-pressing and curing a matrix material, adhesive material, and functional additives. This cold-pressing and curing process significantly reduces energy consumption compared to the high-energy-consuming processes of high-temperature melting and mixing and high-temperature extrusion in existing technologies. Secondly, directly using the physically crushed decommissioned wind turbine blades as the main matrix material not only achieves the direct utilization of all complex components such as glass fiber, resin, and balsa wood in the decommissioned wind turbine blades, but also reduces the generation and sorting difficulty of glass fiber floating matter during recycling compared to the complex and costly chemical degradation process for separating glass fiber, and avoids... The invention avoids secondary pollution caused by chemical degradation. Furthermore, it uses a composite magnesium cement system (MgO + Mg chloride + Mg sulfate) as the adhesive material, which reduces the content of free chloride ions that cause efflorescence from a chemical composition perspective. The addition of a retarder facilitates effective control of the crystallization process of the magnesium cement, resulting in a denser and more stable microstructure and reduced capillary pores. This further blocks moisture migration and salt precipitation, solving the problem of easy deformation of wood-plastic composite boards under specific environments. Finally, the auxiliary bonding of the white glue powder and the full curing of the adhesive material under cold pressing further ensure that a strong whole is formed between the matrix material and the adhesive material.

[0011] Therefore, the composite board provided by this invention fully utilizes the advantages of resin and glass fiber composite materials in retired wind turbine blades. Through a cold-pressing process, the composite material is formed under the synergistic effect of biomass fibers, latex powder, retarders, and functional additives. The entire production process is green and environmentally friendly, with complementary functions of raw material components and excellent microstructural interface bonding. The product possesses advantages such as strong mechanical properties, high dimensional stability, no formaldehyde release, good flame retardancy, and no efflorescence, deformation, or discoloration even after long-term use. It can be widely used in construction, home decoration, and other fields. Simultaneously, it solves three coexisting industry problems: difficulty in high-value utilization of retired blades, significant performance defects in traditional magnesium cement products, and high energy consumption in traditional thermoplastic processes.

[0012] As a preferred embodiment of this technical solution, in the matrix material, the mass percentage of physically crushed decomposing wind turbine blades is 20-40 parts, the mass percentage of biomass fiber is 10-20 parts, and the mass percentage of latex powder is 5-10 parts. Preferably, the physical crushed material of decommissioned wind turbine blades used in this invention is a mixture containing glass fiber, resin, balsa wood, etc., obtained by shearing, crushing and sieving, and the particle size of the physical crushed material of decommissioned wind turbine blades is 5-100 mesh. Preferably, the biomass fiber used in this invention is mainly wood and bamboo processing residues, such as crushed materials of fast-growing wood, bamboo, and crop straw, and the particle size of the biomass fiber is 5-100 mesh, and its size can be greater than or equal to that of physically crushed decommissioned wind turbine blades, with a moisture content of less than 8%. Preferably, the white glue powder used in this invention is an industrial-grade white or off-white powder, the main component of which is ethylene-vinyl acetate copolymer, with polyvinyl alcohol as a protective colloid, and can be quickly dispersed into an emulsion when it comes into contact with water.

[0013] In a preferred embodiment of this technical solution, the adhesive material, by solids, comprises 20-40 parts by mass of magnesium oxide, 7-15 parts by mass of magnesium chloride, 5-10 parts by mass of magnesium sulfate, and the retarder accounts for 3%-6% of the mass of magnesium oxide. Preferably, the magnesium oxide is an industrial-grade powder with an active magnesium oxide content of ≥85% and a particle size of 80-120 mesh; Preferably, the retarder includes any one or both of boric acid and citric acid.

[0014] Preferably, magnesium chloride, boric acid, or citric acid are all of analytical grade.

[0015] Among them, magnesium chloride has high reactivity and can quickly form "magnesium chloride oxychloride cement" with magnesium oxide, providing early strength. However, it has coarse crystals, a loose structure, and residual free chloride ions are the main cause of efflorescence. Magnesium sulfate has a slower reaction rate and can form "magnesium sulfate oxychloride cement" with magnesium oxide. Its crystals are finer and its structure is denser, which can effectively block capillary channels. Moreover, sulfate ions are not hygroscopic, which fundamentally improves water resistance. Boric acid or citric acid, as retarder, do not only "delay solidification" but can also complex Mg. 2+ By precisely controlling the crystallization kinetics of the two competing reactions mentioned above, microcracks are avoided due to rapid exothermic reaction and crystallization stress, allowing time for the formation of a more complete and tightly interwoven crystal network. Therefore, by precisely controlling the rapid strength of magnesium chloride, the dense water resistance of magnesium sulfate, and the retarder, this invention can obtain a stable bulk phase structure with high strength, water resistance, and no halogenation, fundamentally overcoming the inherent defects of "coal cement".

[0016] As a preferred embodiment of this technical solution, the mass concentration of magnesium chloride and magnesium sulfate in the adhesive material is 20%-30%.

[0017] In a preferred embodiment of this technical solution, the functional additives include flame retardants, silane coupling agents, compatibilizers, lubricants, and antioxidants. In the functional additives, the flame retardant accounts for 5-10 parts by mass, the compatibilizer accounts for 4-6 parts by mass, the lubricant accounts for 1-3 parts by mass, the antioxidant accounts for 0.2-0.8 parts by mass, and the silane coupling agent accounts for 0.5%-2% of the physically crushed material of the decommissioned wind turbine blades. Preferably, the flame retardant is an aluminum hydroxide / zinc borate composite flame retardant, wherein both aluminum hydroxide and zinc borate are industrial grade and are mixed in a 1:1 ratio; Preferably, the silane coupling agent is KH550 or KH560, which is mainly used to improve the interfacial properties between materials; Preferably, the compatibilizer is maleic anhydride-grafted polyolefin, wherein the polyolefin is preferably polypropylene or polyethylene, used to adjust the interfacial activity of the material, and has a molecular weight > 100,000. Preferably, the lubricant is a solid paraffin powder with a melting point of 47-64℃, used to adjust the material dispersion effect; Preferably, the antioxidant is antioxidant 1010, used to adjust the weather resistance and aging resistance of the material.

[0018] Secondly, this invention also discloses the preparation method of the above-mentioned composite material based on decommissioned wind turbine blades, which should also fall within the protection scope of this invention, specifically including the following steps: S1. The decommissioned wind turbine blade physical crushed material, biomass fiber and white glue powder are mixed at high speed and evenly to obtain the matrix material. During high-speed mixing, the mixing speed is controlled at 1000r / min-1200r / min and the mixing time is 30-60min. S2. Prepare a mixed aqueous solution of magnesium chloride and magnesium sulfate, and add magnesium oxide and retarder in sequence, stir evenly to obtain an adhesive material, wherein the mass concentration of magnesium chloride and magnesium sulfate is 20%-30%; S3. Place the matrix material, adhesive material and functional additives in a mixer and use the mixer to stir at high speed so that the various materials are fully in contact, mixed evenly and without agglomeration. S4. The uniformly mixed raw materials are dried and dehydrated by passing them through a pipeline dryer to obtain the dried raw materials. S5. The dried raw materials are evenly spread on the pads sprayed with release agent or placed with release paper through the spreading machine, and the slabs are formed with uniform thickness through the continuous rolling equipment, wherein the thickness of the slabs is 10-20mm. S6. Stack the slabs. Specifically, the pre-pressed slabs are assembled in front of the cold press on the pad. After the release paper is placed on the slabs by the robot, they are stacked. When stacking the slabs, there are pressure plates on the top and bottom. The number of slabs is determined by the thickness of the slabs and the opening and closing parameters of the cold press. S7. The stacked slabs are fed into the cold press in one go by the infeed conveyor. The cold pressing pressure and holding time are adjusted according to the quantity and thickness of the products. The slabs are cold pressed to a fixed thickness for the set time period. S8. After the cold pressing time is completed, the upper and lower pressure plates are locked with screws to keep the slab under pressure. The slab under pressure is then conveyed out by the discharge conveyor and transported to the rough slab warehouse for curing to set the shape of the slab. S9. After curing or cooling, the slab is transported into the sanding and sawing production line to carry out processes such as deburring the perimeter, reducing the thickness of the sand, and precise edge trimming to process it into the standard finished product size required for application. Then, performance testing is carried out. After the product quality is qualified, it is sent to the warehouse for use to obtain composite board based on retired wind turbine blades.

[0019] As a preferred embodiment of this technical solution, in step S1, before using the physically crushed material of the decommissioned wind turbine blades, it is pretreated and activated sequentially using a diluted solution of silane coupling agent; Preferably, during the pretreatment, the diluted silane coupling agent is added to the physically crushed material of decommissioned wind turbine blades by spraying or dripping under low-speed stirring, and stirring is continued for 5-10 minutes to obtain wet material; Preferably, the pretreated wet material is placed in a high-speed mixer and activated for 30-60 minutes at a speed of 1000-1200 r / min and a temperature of 80-100℃, so that the physically crushed material of the decommissioned wind turbine blades is dried to a moisture content of less than 10%. Preferably, the concentration of the silane coupling agent diluent is 30%-60%.

[0020] The physical pulverized material of the decommissioned wind turbine blades is an extremely heterogeneous interface containing inert glass fiber / resin and porous hydrophilic balsa wood, exhibiting extremely poor compatibility with the "inorganic magnesium cement matrix." This invention solves the problem of poor interfacial compatibility between glass fiber and resin by pre-treating and high-temperature activating the physical pulverized material of the decommissioned wind turbine blades. The hydrolytic groups of the silane coupling agent form strong Si-O-Si covalent bonds with the hydroxyl groups on the glass fiber surface, while the other end is anchored in the matrix. Secondly, the maleic anhydride graft compatibilizer's non-polar polyolefin chain is compatible with the residual resin in the blades, while the highly polar anhydride groups can react with both the hydroxyl groups of the wood fibers and the Mg in the "magnesium cement hydration products." 2+ The strong ionic / hydrogen bonds formed by hydroxyl groups solve the problem of poor interfacial compatibility between resin / wood fiber and matrix. Therefore, this invention, through the synergistic effect of silane coupling agent and maleic anhydride graft compatibilizer, forms a multi-interfacial bonding mechanism of "covalent bond + ionic / hydrogen bond", achieving unprecedentedly efficient encapsulation and reinforcement of complex leaf pulverized material, and obtaining mechanical strength far exceeding expectations.

[0021] As a preferred embodiment of this technical solution, in step S3, the stirring is performed at a speed of 550-700 r / min for 10-30 min.

[0022] As a preferred embodiment of this technical solution, in step S4, during the drying process, the moisture content of the raw material mixing system is controlled at 50%-60% at a temperature of 80-100℃.

[0023] As a preferred embodiment of this technical solution, in step S7, the cold pressing process involves holding the slab under a unit pressure of 12-15 MPa for 5-10 minutes. In step S8, during the pressure-holding curing process, the upper and lower pressure plates are locked with screws to keep the slab under pressure and cured at 25-60℃ for more than 72 hours to solidify the slab shape.

[0024] The cold pressing of 12-15 MPa in this invention provides sufficient force to allow the slurry to flow, expel air, and achieve initial compaction, while also providing the physical conditions for close contact in the solid-phase reaction. Subsequent medium-temperature pressure curing continuously provides activation energy under pressure, promoting the hydration reaction towards a more stable phase while inhibiting deformation caused by excessive moisture evaporation. Therefore, based on optimized reaction kinetics of the adhesive system and improved flowability of the interface system, this invention, through initial compaction by cold pressing and continuous reaction during curing, can achieve high-performance curing with low energy consumption.

[0025] The composite material based on decommissioned wind turbine blades of the present invention has at least the following beneficial effects: 1. This invention directly uses the physically crushed retired wind turbine blades as the main matrix material, achieving direct utilization of all complex components such as fiberglass, resin, and balsa wood in the retired wind turbine blades. Compared with the complex and costly chemical degradation process to separate fiberglass, this not only significantly reduces recycling costs and energy consumption but also avoids secondary pollution caused by chemical degradation. 2. The "magnesium oxide + magnesium chloride + magnesium sulfate" of this invention forms a "composite magnesium cement system." The introduction of magnesium sulfate creates a "sulfur-oxygen magnesium cement phase" with superior water resistance, which complements the "chlorine-oxygen magnesium cement," reducing the content of free chloride ions that cause efflorescence from a chemical compositional perspective. Simultaneously, the addition of a retarder effectively regulates the crystallization process of the "magnesium cement," resulting in a denser and more stable microstructure, reducing capillary pores, and further preventing moisture migration and salt precipitation. Compared to thermoplastic resins in existing technologies, the "inorganic magnesium cement system" of this invention has natural advantages in heat resistance, creep resistance, and long-term dimensional stability, solving the problem of easy deformation of wood-plastic composite boards under specific environments. 3. In this invention, the glass fiber in the physically crushed material of retired wind turbine blades plays a crucial reinforcing role in the system. Based on this, the auxiliary bonding with white glue powder and the full curing of the adhesive material under cold pressing ensure a strong overall bond between the matrix material and the adhesive material. Therefore, the prepared composite board has mechanical properties such as bending and compressive strength comparable to or surpassing traditional wood-plastic composite boards, while also possessing the non-combustible properties of inorganic materials, thus expanding its application range. 4. This invention is based on composite panels made from retired wind turbine blades and is prepared using a cold-pressing curing process. Compared to the high-energy-consuming processes of high-temperature melting and mixing and high-temperature extrusion in existing technologies, this invention significantly reduces energy consumption during production. Furthermore, the system does not contain formaldehyde or other volatile harmful substances, making the product green and environmentally friendly. Attached Figure Description

[0026] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0027] Figure 1 This is a flowchart illustrating the preparation process of the composite material based on decommissioned wind turbine blades according to the present invention. Detailed Implementation

[0028] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0029] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations according to this application. As used herein, the singular form includes the plural form unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this description, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0030] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Example 1 like Figure 1 As shown, this embodiment provides a method for preparing an 8mm composite plate based on a decommissioned wind turbine blade, including the following steps: S1. Preparation of matrix materials Thirty parts of physically pulverized decommissioned wind turbine blades with a particle size of 60 mesh were selected. Under low-speed stirring, 0.6 parts of a diluted solution of silane coupling agent KH560 (mass concentration of 40%) was added to the pulverized material by spraying or dripping. The mixture was stirred continuously for 5-10 minutes to obtain a wet material. Then, the pretreated wet material was placed in a high-speed mixer and chemically activated at 1100 r / min and 100℃ for 45 minutes, drying the pulverized material until the moisture content was below 10%. Fifteen portions of fast-growing poplar wood shreds with a particle size of 80 mesh and a moisture content of 7% were selected. Select 7.5 parts of industrial-grade white emulsion powder; The three components were placed in a high-speed mixer, and the mixing speed was controlled at 1100 r / min for 30 min to carry out high-speed mixing, so as to obtain a uniformly mixed matrix material. S2. Preparation of adhesive materials 28 parts of industrial-grade powdered magnesium oxide with a particle size of 80 mesh and an activity content of ≥85%, 10.08 parts of analytical grade magnesium chloride, and 7.2 parts of analytical grade magnesium sulfate were selected and prepared into a liquid aqueous solution with a mass concentration of 25% for magnesium chloride and magnesium sulfate; then 1.5 parts of analytical grade citric acid were added to the aqueous solution and stirred evenly to prepare an adhesive material. S3, Mixing First, the matrix materials and adhesive materials prepared in S1 and S2 are loaded into the mixing mill together; Next, functional additives were prepared. Eight parts of industrial-grade aluminum hydroxide and zinc borate were selected to form a composite flame retardant, with the ratio of aluminum hydroxide to zinc borate being 1:1; 4.6 parts of maleic anhydride graft compatibilizer with a molecular weight >100,000 were selected; 2 parts of industrial-grade solid paraffin powder with a melting point of 47-64℃ were selected; and 0.4 parts of antioxidant 1010 were selected. Finally, add the prepared functional additives into the mixer and stir for 20 minutes at a speed of 600 r / min to ensure that the various materials are in full contact, mixed evenly and without agglomeration. S4, Drying The raw materials that are uniformly mixed in S3 are dried and dehydrated through a pipeline dryer at a temperature of 100℃, so that the moisture content of the raw material mixture is controlled at 50%-60%. S5, Laying out the blanks The dried raw materials are evenly spread on a mat with release paper by a spreading machine, and then formed into a 12mm thick slab by a continuous roller pressing device. S6, Stacking The pre-pressed and shaped slabs are assembled in front of the cold press on the pads. After the release paper is placed on the slabs by the robot, they are stacked. Pressure plates are placed on top and bottom when stacking the slabs. S7, Cold Pressing The stacked slabs are fed into the cold press in one go by the infeed conveyor. The unit pressure of the slabs is set to 12MPa and the holding time is 6min. The slabs are then cold-pressed to a fixed thickness. S8, Pressure Maintenance After the cold pressing time is over, the upper and lower pressure plates are locked with screws to keep the slab under pressure. Then, the slab under pressure is sent out by the plate conveyor and transported to the slab warehouse for curing. The warehouse temperature is 40℃ and the curing time is more than 72 hours to fix the shape of the slab. S9, Post-processing After curing or cooling, the slab is transported into the sanding and sawing production line for processes such as deburring the perimeter, reducing the amount of sand to a fixed thickness, and precise edge trimming. It is then processed into the standard finished product size required for application, and performance testing is conducted. Once the product quality is qualified, it is sent to the warehouse for use.

[0032] The composite board prepared in this embodiment has a thickness of 8 mm and its main properties are as follows: density is 1.18 g / cm³. 3 The static bending strength is 21.63 MPa, the elastic modulus is 4580 MPa, the thickness swelling rate after 24 hours of water absorption is 2.15%, the formaldehyde release (desiccator method) was not detected, and the flame retardant performance level is A2.

[0033] Example 2 like Figure 1 As shown, this embodiment provides a method for preparing a 12mm composite plate using decommissioned wind turbine blades, specifically including the following steps: S1. Preparation of matrix materials Twenty-five portions of physically pulverized decommissioned wind turbine blades with a particle size of 20 mesh were selected. Under low-speed stirring, 0.4 portions of a diluted solution of silane coupling agent KH550 (mass concentration of 50%) were added to the pulverized material by spraying or dripping. The mixture was stirred continuously for 5-10 minutes to obtain a wet material. Then, the pretreated wet material was placed in a high-speed mixer and chemically activated at 1200 r / min and 80℃ for 45 minutes, allowing the pulverized material to dry to a moisture content of less than 10%. 12.5 parts of fast-growing poplar wood shreds with a particle size of 60 mesh and a moisture content of 8% were selected; Select 6.5 parts of industrial-grade white emulsion powder; The three components were placed in a high-speed mixer, and the mixing speed was controlled at 1200 r / min for 30 min to achieve high-speed mixing and obtain a uniformly mixed matrix material. S2. Preparation of adhesive materials 30 parts of industrial-grade powdered magnesium oxide with a particle size of 80 mesh and an activity content of ≥85%, 12 parts of analytical grade magnesium chloride, and 8 parts of analytical grade magnesium sulfate were selected and prepared into a liquid aqueous solution with a mass concentration of 25% for magnesium chloride and magnesium sulfate; then 1.2 parts of analytical grade citric acid were added to the aqueous solution and stirred evenly to prepare an adhesive material. S3, Mixing First, the matrix materials and adhesive materials prepared in S1 and S2 are loaded into the mixing mill together; Next, functional additives were prepared. 10 parts of industrial-grade aluminum hydroxide and zinc borate were selected to form a composite flame retardant with a ratio of 1:1. 5 parts of maleic anhydride graft compatibilizer with a molecular weight >100,000 were selected. 1 part of industrial-grade solid paraffin powder with a melting point of 47-64℃ was selected. 0.5 parts of antioxidant 1010 were selected. Finally, add the prepared functional additives into the mixer and stir for 25 minutes at a speed of 650 r / min to ensure that the various materials are in full contact, mixed evenly and without agglomeration. S4, Drying The raw materials that are uniformly mixed in S3 are dried and dehydrated through a pipeline dryer at a temperature of 100℃, so that the moisture content of the raw material mixture is controlled at 50%-60%. S5, Laying out the blanks The dried raw materials are evenly spread on a mat with release paper by a spreading machine, and then formed into a 18mm thick slab by a continuous roller pressing device. S6, Stacking The pre-pressed and shaped slabs are assembled in front of the cold press on the pads. After the release paper is placed on the slabs by the robot, they are stacked. Pressure plates are placed on top and bottom when stacking the slabs. S7, Cold Pressing The stacked slabs are fed into the cold press in one go by the infeed conveyor. The unit pressure of the slabs is set to 15MPa and the holding time is 10min. The slabs are then cold-pressed. S8, Pressure Maintenance After the cold pressing time is over, the upper and lower pressure plates are locked with screws to keep the slab under pressure. Then, the slab under pressure is sent out by the plate conveyor and transported to the raw slab warehouse for curing. The warehouse temperature is 50℃ and the curing time is more than 72 hours to fix the shape of the slab. S9, Post-processing After curing or cooling, the slab is transported into the sanding and sawing production line for processes such as deburring the perimeter, reducing the amount of sand to a fixed thickness, and precise edge trimming. It is then processed into the standard finished product size required for application, and performance testing is conducted. Once the product quality is qualified, it is sent to the warehouse for use.

[0034] The composite board prepared in this embodiment has a thickness of 12 mm and its main properties are as follows: density is 1.32 g / cm³. 3 The static bending strength is 23.9 MPa, the elastic modulus is 4520 MPa, the thickness swelling rate after 24 hours of water absorption is 1.82%, the formaldehyde release (desiccator method) was not detected, and the flame retardant performance level is A2.

[0035] Compare with Example 1 The process in this comparative example is as follows: Figure 1As shown, the composite board is 10mm thick, and the specific steps include: S1. Preparation of matrix materials Thirty-five portions of physically pulverized decommissioned wind turbine blades with a particle size of 60 mesh were selected. Under low-speed stirring, 0.7 portions of a diluted solution of silane coupling agent KH560 (mass concentration of 40%) were added to the pulverized material by spraying or dripping. The mixture was stirred continuously for 5-10 minutes to obtain a wet material. Then, the pretreated wet material was placed in a high-speed mixer and chemically activated at 1200 r / min and 80℃ for 50 minutes, allowing the pulverized material to dry to a moisture content of less than 10%. Seventeen portions of fast-growing poplar wood shreds with a particle size of 60 mesh and a moisture content of 8% were selected. Eight parts of industrial-grade white emulsion powder were selected; The three components were placed in a high-speed mixer, and the mixing speed was controlled at 1200 r / min for 30 min to achieve high-speed mixing and obtain a uniformly mixed matrix material. S2. Preparation of adhesive materials 25 parts of industrial-grade powdered magnesium oxide with a particle size of 80 mesh and an activity content of ≥85%, 9 parts of analytical grade magnesium chloride, and 6 parts of analytical grade magnesium sulfate were selected and prepared into a liquid aqueous solution with a mass concentration of 25% for magnesium chloride and magnesium sulfate; then 2 parts of analytical grade citric acid were added to the aqueous solution and stirred evenly to prepare an adhesive material. S3, Mixing First, the matrix materials and adhesive materials prepared in S1 and S2 are loaded into the mixing mill together; Next, prepare functional additives without adding composite flame retardants. Select 5.2 parts of maleic anhydride graft compatibilizer with a molecular weight >100,000; select 3 parts of industrial-grade solid paraffin powder with a melting point of 47-64℃; and select 0.4 parts of antioxidant 1010. Finally, add the prepared functional additives into the mixer and stir for 25 minutes at a speed of 650 r / min to ensure that the various materials are in full contact, mixed evenly and without agglomeration. S4, Drying The raw materials that are uniformly mixed in S3 are dried and dehydrated through a pipeline dryer at a temperature of 100℃, so that the moisture content of the raw material mixture is controlled at 50%-60%. S5, Laying out the blanks The dried raw materials are evenly spread on a mat with release paper by a spreading machine, and then formed into a 18mm thick slab by a continuous roller pressing device. S6, Stacking The pre-pressed and shaped slabs are assembled in front of the cold press on the pads. After the release paper is placed on the slabs by the robot, they are stacked. Pressure plates are placed on top and bottom when stacking the slabs. S7, Cold Pressing The stacked slabs are fed into the cold press in one go by the feed conveyor. The unit pressure of the slabs is set to 15MPa and the holding time is 8min. The slabs are then cold pressed. S8, Pressure Maintenance After the cold pressing time is over, the upper and lower pressure plates are locked with screws to keep the slab under pressure. Then, the slab under pressure is sent out by the plate conveyor and transported to the raw slab warehouse for curing. The warehouse temperature is 50℃ and the curing time is more than 72 hours to fix the shape of the slab. S9, Post-processing After curing or cooling, the slab is transported into the sanding and sawing production line for processes such as deburring the perimeter, reducing the amount of sand to a fixed thickness, and precise edge trimming. It is then processed into the standard finished product size required for application, and performance testing is conducted. Once the product quality is qualified, it is sent to the warehouse for use.

[0036] The composite board prepared in this comparative example has a thickness of 10 mm and its main properties are as follows: density is 1.23 g / cm³. 3 It has a static bending strength of 26.87 MPa, an elastic modulus of 5630 MPa, a 24-hour water absorption thickness expansion rate of 4.33%, and a flame retardant rating of B1.

[0037] Compare with Example 2 This comparative example is basically the same as Example 1, except that the retarder citric acid was not added.

[0038] The composite board prepared in this comparative example has a thickness of 8 mm and its main properties are as follows: density is 1.08 g / cm³. 3 The static bending strength is 16.92 MPa, the elastic modulus is 3880 MPa, and the thickness expansion rate after 24 hours of water absorption is 4.16%.

[0039] Compare with Example 3 This comparative example is basically the same as Example 1, except that: no silane coupling agent was used to pretreat and activate the physically crushed material of the decommissioned wind turbine blades.

[0040] The composite board prepared in this comparative example has a thickness of 8 mm and its main properties are as follows: density is 1.13 g / cm³. 3 The static bending strength is 17.4 MPa, the elastic modulus is 4360 MPa, and the thickness expansion rate after 24 hours of water absorption is 4.83%.

[0041] Compare with Example 4 The difference between this comparative example and Example 1 is that: the leaf powder is 40 parts, poplar powder is 20 parts, magnesium oxide is 10 parts, magnesium chloride is 8 parts, magnesium sulfate is 6 parts, citric acid is 0.5 parts, and other ingredients and process parameters are basically the same.

[0042] The composite board prepared in this comparative example has a thickness of 8 mm and its main properties are as follows: density is 0.88 g / cm³. 3 The static bending strength is 23.85 MPa, the elastic modulus is 5120 MPa, and the thickness expansion rate after 24 hours of water absorption is 5.76%.

[0043] Compare with Example 5 The difference between this comparative example and Example 1 is that: the leaf powder is 18 parts, poplar powder is 9 parts, magnesium oxide is 42 parts, magnesium chloride is 18 parts, magnesium sulfate is 11 parts, citric acid is 3 parts, and other ingredients and process parameters are basically the same.

[0044] The composite board prepared in this comparative example has a thickness of 8 mm and its main properties are as follows: density is 1.38 g / cm³. 3 The static bending strength is 18.24 MPa, the elastic modulus is 3620 MPa, and the thickness expansion rate after 24 hours of water absorption is 2.06%.

[0045] The performance test results of the composite boards obtained in Examples 1 and 2 of the present invention and Comparative Examples 1-5 are summarized in Table 1.

[0046] Table 1 Test Results

[0047] By comparing the experimental data of Examples 1 and 2 in Table 1, it can be seen that the composite board prepared by the preparation method provided by the present invention has excellent microstructure interface bonding, strong mechanical properties, high dimensional stability, no formaldehyde release, good flame retardant properties, and will not effloresce or deform and discolor after long-term use. It can be widely used in construction, home decoration and other fields.

[0048] In contrast, Comparative Example 1, which did not introduce flame retardant, showed improved static bending strength and modulus of elasticity due to the increased proportion of leaf shreds and wood flour. However, the 24-hour water absorption thickness expansion rate was significantly increased, and the flame retardant rating was B1. This indicates that the flame retardant has a significant inhibitory effect on the combustion performance of leaf shreds and wood flour, making the flame retardant crucial in the preparation technology of this composite board.

[0049] In Comparative Example 2, no retarder was added, which resulted in a decrease in the static bending strength and elastic modulus of the composite board, while the 24-hour water absorption thickness expansion rate increased significantly. This indicates that the retarder is crucial for improving crystallinity and stability, and also has a certain impact on properties such as water resistance and anti-efflorescence.

[0050] Compared with Example 3, no silane coupling agent was used to pretreat and activate the physically crushed material of the decommissioned wind turbine blades, which resulted in a significant decrease in the static bending strength and elastic modulus of the composite board, while the 24-hour water absorption thickness expansion rate also increased significantly, indicating that interface pretreatment is the key to obtaining high mechanical strength.

[0051] When the amounts of each component in Examples 4 and 5 exceeded the preferred range of the present invention, the composite board exhibited certain deficiencies in various aspects of its performance, indicating that the proportioning range of the present invention is the optimal range after optimization.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A composite board based on decommissioned wind turbine blades, characterized in that, The raw materials including 40-60 parts of base material, 40-60 parts of adhesive material and 10-20 parts of functional additives are prepared by cold pressing and curing, The base material comprises physical crushing material of retired wind turbine blade, biomass fiber and white glue powder; The adhesive material is a mixture of aqueous solution of magnesium oxide, magnesium chloride, magnesium sulfate and retarder.

2. The composite panel based on decommissioned wind turbine blades according to claim 1, characterized in that, In the base material, the mass ratio of the physical crushing material of retired wind turbine blade is 20-40 parts, the mass ratio of the biomass fiber is 10-20 parts, and the mass ratio of the white glue powder is 5-10 parts; Preferably, the particle size of the physical crushing material of retired wind turbine blade is 5-100 mesh; Preferably, the particle size of the biomass fiber is 5-100 mesh, and the water content is less than 8%.

3. The composite panel based on decommissioned wind turbine blades according to claim 1, characterized in that, In the adhesive material, the mass ratio of magnesium oxide is 20-40 parts, the mass ratio of magnesium chloride is 7-15 parts, and the mass ratio of magnesium sulfate is 5-10 parts; The mass of the retarder accounts for 3%-6% of the mass of magnesium oxide; Preferably, the magnesium oxide is an industrial grade powder, the content of active magnesium oxide is ≥85%, and the particle size is 80-120 mesh; Preferably, the retarder includes any one or both of boric acid and citric acid.

4. The composite panel based on decommissioned wind turbine blades according to claim 1, characterized in that, In the adhesive material, the mass concentration of magnesium chloride and magnesium sulfate is 20%-30%.

5. The composite panel based on decommissioned wind turbine blades according to claim 1, characterized in that, The functional additives include flame retardant, silane coupling agent, compatibilizer, lubricant and antioxidant, In the functional additives, the mass ratio of the flame retardant is 5-10 parts, the mass ratio of the compatibilizer is 4-6 parts, the mass ratio of the lubricant is 1-3 parts, and the mass ratio of the antioxidant is 0.2-0.8 parts; The mass of the silane coupling agent accounts for 0.5%-2% of the mass of the physical crushing material of retired wind turbine blade; Preferably, the flame retardant is aluminum hydroxide / zinc borate composite flame retardant; Preferably, the silane coupling agent is KH550 or KH560; Preferably, the compatibilizer is maleic anhydride grafted polyolefin; Preferably, the lubricant is solid paraffin powder with a melting point of 47-64℃; Preferably, the antioxidant is antioxidant 1010.

6. A method for preparing a composite board based on decommissioned wind turbine blades, characterized in that, The method comprises the following steps: S1, the physical crushing material of retired wind turbine blade, biomass fiber and white glue powder are stirred at high speed, mixed uniformly, and the base material is obtained; S2, the mixed aqueous solution of magnesium chloride and magnesium sulfate is prepared, and magnesium oxide and retarder are added in turn, stirred uniformly, and the adhesive material is obtained; S3, the base material, adhesive material and functional additives are placed in a mixing machine for stirring, and a mixed raw material is obtained; S4, the mixed raw material is dried and dehydrated to obtain a dried raw material; S5, the dried raw material is placed on a pad sprayed with release agent or placed with release paper, and a slab is formed by continuous rolling; S6, the slab is stacked; S7, the stacked slab is cold pressed; S8, the slab after cold pressing is cured under pressure; S9, the slab after curing under pressure is post-treated to obtain a composite board based on retired wind turbine blade.

7. The method of claim 6, wherein the method further comprises the step of: In step S1, before the retired wind power blade physical crushing material is used, the dilute solution of silane coupling agent is used for pretreatment and activation treatment in sequence; Preferably, in the pretreatment, the dilute solution of silane coupling agent is added into the retired wind power blade physical crushing material in the form of spraying or dropping under low-speed stirring, and the stirring is continued for 5-10 min to obtain wet material; Preferably, the pretreated wet material is placed in a high-speed stirrer, and the activation treatment is carried out at a rotation speed of 1000-1200 r / min and a temperature of 80-100℃ for 30-60 min, so that the retired wind power blade physical crushing material is dried to a water content of less than 10%.

8. The method of claim 6, wherein the method further comprises the step of: In step S3, the stirring is carried out at a rotation speed of 550-700 r / min for 10-30 min.

9. The method of claim 6, wherein the method further comprises the step of: In step S4, the drying is carried out at a temperature of 80-100℃, and the water content of the raw material mixture system is controlled to be 50%-60%.

10. The method of claim 6, wherein the method further comprises the step of: In step S7, the cold pressing treatment is carried out at a unit pressure of 12-15 MPa for 5-10 min. In step S8, the pressure maintaining and curing are carried out by locking the upper and lower pressure plates by a screw rod to maintain the pressure state of the plate blank, and the plate blank is cured at 25-60℃ for more than 72 h to shape the plate blank.

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