A high-strength, lightweight, environmentally friendly fiber composite board and its production method

Abstract

This invention discloses a high-strength, lightweight, environmentally friendly fiber composite board and its production method, belonging to the field of composite board technology. It addresses the technical problems of poor fire resistance and lack of waterproofing treatment for fiber boards with strong moisture absorption in existing technologies. The production method of the high-strength, lightweight, environmentally friendly fiber composite board prepared by this invention includes the following steps: "Three-residue" wood raw materials undergo preprocessing to obtain fiber raw materials; then, the fiber raw materials are impregnated in an ethanol solution of dodecyltrimethylsiloxane, polydopamine, and isophorone diisocyanate to prepare superhydrophobic modified fibers; diatomaceous earth powder of a certain particle size, refractory oxide hollow glass microspheres, coarse aggregate, and fine aggregate are mixed to prepare a lightweight inorganic refractory material mixture; finally, a high-strength, lightweight, environmentally friendly fiber composite board with a certain composite structure is prepared.

Description

Technical Field

[0001] This invention relates to the field of composite board technology, specifically to a high-strength, lightweight, environmentally friendly fiber composite board and its production method. Background Technology

[0002] Fiberboard is a type of board made from wood fibers or other plant fibers as raw materials, with or without resin, and heated or simultaneously pressed. The wood raw materials used in the production of fiberboard are mainly "three residues", namely logging residues (branches, tree tops, roots, etc.), timber processing residues (timber cut-offs, branches, etc.), and processing residues (bark, strips, scraps, etc.). Fiberboard, as a wood fiber base material, can effectively utilize wood resource residues and improve the utilization rate of wood resources.

[0003] However, with the rapid development of science and technology, people have higher and higher requirements for the performance and function of materials. Using fiberboard as the base material, composite boards with lightweight, high strength, fire resistance and hydrophobic properties can be prepared, so that composite boards can be applied to more scenarios and fields to meet more different needs of people, which has important practical value.

[0004] Invention patent CN113265158B discloses a method for preparing an environmentally friendly flame-retardant high-strength fiber composite board. The above-mentioned prior art first utilizes a wrinkled layered material, carbonaceous material, amination carboxyl agent chitosan-modified silica and phthalic anhydride-modified polyurethane film, which are cured as modified epoxy resin. Then, the modified epoxy resin is mixed with pretreated wood fibers, and then mixed with raw materials such as calcium oxide and ammonium acetate to obtain a mixture. The mixture is then subjected to multiple hot pressings to prepare an environmentally friendly flame-retardant high-strength fiber composite board.

[0005] The aforementioned invention improves the strength and flame retardant properties of the composite board by leveraging the interaction forces between various incorporated components. However, compared to setting a fireproof layer alone, the fire resistance of the board prepared by incorporating fireproof materials is slightly insufficient. Furthermore, as a hydrophilic material, wood fiber has strong hygroscopic and water-absorbing properties when used to make fiberboard. After absorbing moisture, the fiberboard's strength decreases, its heat transfer and electrical conductivity increase, and it becomes more susceptible to corrosion, thus affecting the product's performance and lifespan. Therefore, the aforementioned fiberboard also needs to undergo hydrophobic treatment.

[0006] To address this technical deficiency, a solution is proposed. Summary of the Invention

[0007] The purpose of this invention is to provide a high-strength, lightweight, and environmentally friendly fiber composite board and its production method, which solves the drawback of the prior art where the fiber substrate with strong moisture properties is not hydrophobically treated, resulting in poor performance of the prepared composite fiber board after absorbing moisture; in addition, the strength and fire resistance of the fiber board need to be further improved.

[0008] The objective of this invention can be achieved through the following technical solution: a method for producing high-strength, lightweight, and environmentally friendly fiber composite panels, comprising the following steps:

[0009] S1. Stacking and storage of timber raw materials and preparation of wood chips: The timber raw materials of "three residues" are stacked and stored for 1-2 months. The stacking height of the timber raw materials is 20-30m and the stacking spacing is maintained at 1-3m. During the stacking process, the moisture content of the timber raw materials is 10%-15%wt. Then the timber raw materials are cut, magnetically separated, washed and debarked to obtain wood chips for making fiberboard.

[0010] S2. Preparation of fiber raw materials: Wood chips are separated into monomer fibers by hot grinding process. The monomer fibers are then softened by pressure cooking, ground to 100-200 mesh, and then dried to prepare fiber raw materials.

[0011] S3. Preparation of superhydrophobic modified fibers: dodecyltrimethylsiloxane , Polydopamine and Isophorone diisocyanate esters The mixture is dissolved in ethanol to obtain a mixed solution; the fiber raw material is impregnated in the mixed solution for 100 min to obtain superhydrophobic modified fiber;

[0012] S4. Preparation of high-strength lightweight and environmentally friendly fiber composite board: Superhydrophobic modified fiber, acrylic emulsion, anti-caking modifier and curing agent are mixed evenly and molded to prepare fiber substrate;

[0013] S5. A fiber substrate is used as the first substrate. An epoxy resin adhesive is uniformly coated on one side of the first substrate to obtain a first adhesive layer. A modified inorganic refractory material mixture is uniformly coated on the first adhesive layer to obtain an inorganic metal layer. An epoxy resin adhesive is uniformly coated on the inorganic metal layer to obtain a second adhesive layer. A fiber substrate is covered on the second adhesive layer to form a second substrate, thus forming a composite board of first substrate—first adhesive layer—inorganic metal layer—second adhesive layer—second substrate.

[0014] S6. The composite board is hot-pressed, vulcanized, and cooled in a dispersed manner to obtain a high-strength, lightweight, and environmentally friendly fiber composite board.

[0015] Furthermore, in step S2, in the thermal grinding process, the centripetal force of the refiner is 100-150N, the fiber separation time is 10-20min, and the grinding time is 60min; in the pressurized cooking and softening process, the cooking temperature is 150-160℃, and the cooking time is 2-3h.

[0016] In this invention, the raw materials of "three residues" are first collected and stacked for storage. During the storage process, the raw materials are naturally dried, the moisture content is balanced, and the content of resin and pectin is reduced. The raw materials such as small-diameter timber, branches, and processing residues provided for the production of fiberboard are often mixed with impurities such as sludge and sand. Therefore, a series of processes such as chipping, screening, crushing, magnetic separation, dehydration, and debarking are required to prepare wood chips suitable for making fiberboard.

[0017] Further, in step S3, the ratio of the amount of dodecyltrimethylsiloxane, polydopamine, isophorone diisocyanate and anhydrous ethanol is 30mL:15-30g:22mL:500mL.

[0018] Organosilicon compounds are common low surface energy compounds with excellent resistance to oxidation, radiation, weathering, and hydrophobicity. They have significant advantages as hydrophobic surface coatings. The dodecyltrimethylsiloxane selected in this invention has long alkane side chains. When applied to the fiber surface, it can impart good hydrophobicity to the fiber surface. In addition, the siloxy groups can combine with and dehydrate the hydroxyl bonds on the surface of the fiber raw materials and the modified inorganic refractory mixture, thereby improving the overall strength and mechanical properties of the material.

[0019] Isophorone diisocyanate contains active -NCO groups, which can react not only with the -OH bonds of modified inorganic refractory mixtures and fiber raw materials, but also with the amino and catechol groups on the surface of polydopamine. The addition of polydopamine further enhances the adhesive properties of the prepared superhydrophobic modified fibers and epoxy resin adhesives. In addition, the adsorption and complexation of polydopamine, isophorone diisocyanate and fiber raw materials enable the fiber substrate to be integrally formed without the addition of curing agents and adhesives.

[0020] Furthermore, in step S5, the method for preparing lightweight inorganic refractory materials includes the following steps:

[0021] A1. Grind diatomaceous earth to a particle size of 10-20 mm to obtain diatomaceous earth powder;

[0022] A2. Refractory oxide hollow glass microspheres with a diameter of 5 mm were subjected to flotation to obtain refractory oxide hollow glass microspheres.

[0023] A3. The unshaped refractory aggregate was ball-milled using a micro ball mill to obtain coarse aggregate with a particle size of 5-10 mm and fine aggregate with a particle size of 0.01-5 mm.

[0024] A4. Mix diatomaceous earth powder, refractory oxide hollow glass microspheres, coarse aggregate and fine aggregate in a mass ratio of 1:1:0.5:0.5 to obtain an inorganic refractory material mixture. Mix the inorganic refractory material mixture and organic binder in a mass ratio of 10:1 to obtain a lightweight inorganic refractory material.

[0025] The lightweight inorganic refractory material prepared by this invention includes diatomaceous earth, hollow refractory oxide spheres, and unshaped refractory aggregates. Diatomaceous earth is a porous thermal insulation material with a pore size ranging from tens to hundreds of nanometers. It can be used as a raw material for medium- and high-temperature thermal insulation materials. At 500-800℃, all moisture is evaporated, forming countless pores inside. The pores of diatomaceous earth are very fine, providing excellent heat shielding. The hollow refractory oxide spheres are hollow spherical particles of thermal insulation material formed from materials such as alumina, magnesium oxide, mullite, and aluminum spinel, with a sphere diameter of about 5mm. Based on the diameter of the hollow refractory oxide spheres, unshaped aggregates are then added. Refractory aggregates are used to achieve the compounding of inorganic refractory materials, obtaining the optimal bulk density of the inorganic refractory mixture, thereby achieving the best refractory performance. Among them, according to the spherical diameter of the hollow spherical granular insulation material, coarse aggregates with a size of 5-10mm and fine aggregates with a size of 0.01-5mm are compounded. The coarse aggregates act as a skeleton in the inorganic refractory materials, while the fine aggregates fill the pores. In addition, the raw materials for hollow glass microspheres and amorphous refractory aggregates are widely available and readily available. Using carboxymethyl cellulose and dextrin as organic binders can improve the interfacial bonding force between the prepared inorganic metal layer and the adhesive.

[0026] Furthermore, the refractory oxide hollow glass microspheres include any one of hollow glass microspheres formed from alumina, magnesium oxide, mullite, and aluminum spinel materials, and combinations thereof; the raw materials for the coarse aggregate and fine aggregate are any one of aluminosilicate clinker, mullite, corundum, silicon carbide, and silicon nitride, and combinations thereof.

[0027] Furthermore, the coating thickness of the inorganic metal layer is 0.2-0.5 mm, and the coating thickness of the first adhesive layer and the second adhesive layer is 0.2-0.5 mm.

[0028] Furthermore, in the hot pressing process, the hot pressing pressure is 1 MPa, the hot pressing temperature is 90-130℃, and the hot pressing time is 0.5-2 min / mm; in the vulcanization process, the vulcanization time is 5-10 min, the vulcanization temperature is 45-65℃, and the vulcanization pressure is 1-2 MPa; the dispersed cooling process specifically involves placing the high-strength, lightweight, environmentally friendly fiber composite board in a treatment chamber for humidity conditioning treatment; wherein, the temperature of the treatment chamber is 70-80℃, the relative humidity of the treatment chamber is 75%-90%, and after treatment, the moisture content of the board is 7%-8%.

[0029] In the hot pressing process, the formed fiberboard blank is pressed into a fiberboard with the required thickness, density and physical properties by heating and pressurizing. The hot pressing process is a complex physical and chemical change process, including compacting the blank to make the fibers come into close contact, raising the temperature to vaporize the moisture inside the fiberboard blank, and curing the adhesive.

[0030] The present invention has the following beneficial effects:

[0031] This invention uses forest "three residues" as raw materials. After a series of pre-processing steps, fiber raw materials suitable for use as fiber substrates are obtained. Then, the fiber raw materials are impregnated in a mixed solution composed of dodecyltrimethylsiloxane, polydopamine, and isophorone diisocyanate to prepare superhydrophobic modified fibers. Among them, dodecyltrimethylsiloxane improves the hydrophobic properties of the modified fibers, while polydopamine and isophorone diisocyanate utilize their own active functional groups to improve the bonding force between waterproof coatings and fiber raw materials, and between fiber raw materials and epoxy resin adhesives.

[0032] In the composite board structure designed in this invention, fine diatomaceous earth powder, refractory oxide hollow glass microspheres, coarse aggregate and fine aggregate are compounded and modified with an organic binder to obtain a lightweight inorganic refractory material. By precisely controlling the particle size of each inorganic refractory material component, the optimal bulk density is achieved, thereby obtaining the best refractory performance.

[0033] This invention involves designing a composite substrate structure consisting of a first substrate, a first adhesive layer, an inorganic metal layer, a second adhesive layer, and a second substrate, followed by a series of post-processing steps to prepare a composite fiberboard that combines high strength, lightweight, hydrophobicity, and fire resistance. Detailed Implementation

[0034] 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention. Example 1

[0035] This embodiment provides a method for producing high-strength, lightweight, and environmentally friendly fiber composite panels, including the following steps:

[0036] S1. Stacking and storage of timber raw materials, and preparation of wood chips.

[0037] The "three residues" of wood raw materials were stacked and stored for 2 months. The stack height was 20m and the stack spacing was maintained at 1m. During the stacking process, the moisture content of the wood raw materials was controlled at 10%wt. Then, a drum chipper was used to cut the wood raw materials to obtain wood chips with a size of 25mm×20mm×3mm. Wood chips that exceeded the specified size were further crushed. After further crushing, the small fragments that did not meet the process requirements were screened and burned as fuel. The wood chips were then passed through a magnetic separator to detect and remove metal objects mixed in with the wood chips. The wood chips were then washed by a spiral dewatering washing machine and debarked by an air extrusion process to obtain wood chips.

[0038] S2, Preparation of fiber raw materials

[0039] The wood chips were separated into monomer fibers by thermal grinding. The centripetal force of the grinding mill was 100N, the fiber separation time was 20min, and the grinding time was 60min. The monomer fibers were then pressure-cooked and softened, ground, and vacuum-dried at 80℃ for 60min to obtain fiber raw materials. The cooking temperature was 160℃ and the cooking time was 2.2h.

[0040] S3. Preparation of superhydrophobic modified fibers

[0041] 30 mL of dodecyltrimethylsiloxane, 15 mL of polydopamine, and 22 mL of isophorone diisocyanate were mixed and dissolved in 500 mL of ethanol to obtain a mixed solution. The fiber raw material was then fully impregnated in the mixed solution for 100 min to obtain superhydrophobic modified fiber.

[0042] S4. Preparation of lightweight inorganic refractory mixture

[0043] 1) Grind diatomaceous earth to a particle size of 10 mm to obtain diatomaceous earth powder;

[0044] 2) Flotation of hollow glass microspheres of refractory oxide with a particle size of about 5 mm: 100 g of hollow glass microspheres of alumina were placed in a beaker, 500 mL of deionized water was added, and then the beaker was placed on a magnetic stirrer and stirred at 100 r / min for 33 min, and then allowed to stand for 2 h; the hollow glass microspheres floating on the water surface were taken and then dried at 105 ℃ for 12 h in a vacuum environment to obtain hollow glass microspheres with complete particle size;

[0045] 3) Prepare unshaped refractory aggregates by using aluminosilicate clinker, mullite, corundum and silicon carbide as raw materials, and ball milling them with a micro ball mill to obtain coarse aggregates with a particle size of 5-10 mm and fine aggregates with a particle size of 0.01-5 mm.

[0046] 4) Mix 100 mg of diatomaceous earth powder, 100 mg of alumina hollow glass microspheres, 50 mg of coarse aggregate and 50 mg of fine aggregate evenly to obtain an inorganic refractory material mixture. Mix the inorganic refractory material mixture with 30 g of dextrin at 100 r / min evenly to prepare a lightweight inorganic refractory material.

[0047] S5. Preparation of high-strength, lightweight, and environmentally friendly fiber composite boards.

[0048] Superhydrophobic modified fibers were laid flat in a 250mm×250mm molding mold, pre-pressed at 1.0MPa, then hot-pressed at 190℃ for 10min, and left at room temperature for 24h to prepare a fiber substrate. The fiber substrate served as the first substrate, and an epoxy resin adhesive was uniformly coated on one side of the first substrate to obtain a first adhesive layer. Then, an inorganic refractory material mixture was uniformly coated on the first adhesive layer to obtain an inorganic metal layer. Then, an epoxy resin adhesive was uniformly coated on the inorganic metal layer to obtain a second adhesive layer. Wood fiberboard was covered on the second adhesive layer to form a second substrate, thus forming a composite board of first substrate—first adhesive layer—inorganic metal layer—second adhesive layer—second substrate. The coating thickness of the inorganic metal layer was 0.2mm, and the coating thickness of the first adhesive layer and the second adhesive layer was 0.2mm.

[0049] The composite board is placed in a hot press for hot pressing; the hot pressing pressure is 1MPa, the hot pressing temperature is 90℃, and the hot pressing time is 1.5min / mm. The hot-pressed composite board is then placed in a flat vulcanizing machine for secondary shaping to obtain a high-strength, lightweight, and environmentally friendly fiber composite board. The vulcanizing time is 5min, the vulcanizing temperature is 45℃, and the vulcanizing pressure is 1MPa.

[0050] S6, Fiberboard post-processing

[0051] After the fiberboard completes the hot pressing process, it is cooled by a scattered cooling method to reduce the internal temperature of the core material to 60°C, resulting in a cooled fiberboard. The cooled fiberboard is then placed in a treatment chamber for humidity conditioning; the placement time is 5 hours; the temperature of the treatment chamber is 70°C and the relative humidity is 75%; after the treatment, the moisture content of the fiberboard is 7%, thus preparing a high-strength, lightweight, and environmentally friendly fiber composite board. Example 2

[0052] This embodiment provides a method for producing high-strength, lightweight, and environmentally friendly fiber composite panels, including the following steps:

[0053] S1. Stacking and storage of timber raw materials, and preparation of wood chips.

[0054] The "three residues" of wood raw materials were stacked and stored for 2 months. The stack height was 23m and the stack spacing was maintained at 1.5m. During the stacking process, the moisture content of the wood raw materials was controlled at 12%wt. Then, a drum chipper was used to cut the wood raw materials to obtain wood chips with a size of 25mm×20mm×3mm. Wood chips that exceeded the specified size were further crushed. After further crushing, the small fragments that did not meet the process requirements were screened and burned as fuel. The cut wood chips were passed through a magnetic separator to detect and remove metal objects mixed in with the wood chips. Then, the wood chips were washed by a spiral dewatering washing machine and debarked by an air extrusion process to obtain wood chips.

[0055] S2, Preparation of fiber raw materials

[0056] Monomer fibers were separated from wood chips using a hot grinding method. The centripetal force of the grinding mill was 100N, the fiber separation time was 22min, and the grinding time was 63min. The monomer fibers were then pressure-cooked to soften them, ground, and vacuum-dried at 80℃ for 61min to obtain fiber raw materials. The cooking temperature was 160℃ and the cooking time was 2h.

[0057] S3. To prepare superhydrophobic modified fibers, 30 mL of dodecyltrimethylsiloxane, 17 mL of polydopamine, and 22 mL of isophorone diisocyanate were mixed and dissolved in 500 mL of ethanol to obtain a mixed solution. The fiber raw material was fully immersed in the mixed solution for 100 min to obtain superhydrophobic modified fibers.

[0058] S4. Preparation of lightweight inorganic refractory mixture

[0059] 1) Grind diatomaceous earth to a particle size of 10 mm to obtain diatomaceous earth powder;

[0060] 2) Flotation of refractory oxide hollow glass microspheres with a particle size of approximately 5 mm: 100 g of magnesium oxide hollow glass microspheres were placed in a beaker, 500 mL of deionized water was added, and the mixture was stirred at 100 r / min for 35 min on a magnetic stirrer, followed by standing for 2 h. The hollow glass microspheres floating on the water surface were then dried at 101 °C for 12 h under vacuum to obtain hollow glass microspheres with a complete particle size. The raw material for the hollow glass microspheres was alumina.

[0061] 3) Preparation of unshaped refractory aggregates

[0062] Using aluminosilicate clinker, mullite, corundum, and silicon carbide as raw materials, a micro ball mill was used for ball milling to obtain coarse aggregate with a particle size of 5-10 mm and fine aggregate with a particle size of 0.01-5 mm, respectively.

[0063] 4) Mix 100 mg of diatomaceous earth powder, 100 mg of magnesium oxide hollow glass microspheres, 50 mg of coarse aggregate and 50 mg of fine aggregate evenly to obtain an inorganic refractory material mixture; mix the inorganic refractory material mixture with 30 g of methyl cellulose at 100 r / min evenly to prepare a lightweight inorganic refractory material.

[0064] S5. Preparation of high-strength, lightweight, and environmentally friendly fiber composite boards.

[0065] Superhydrophobic modified fibers were laid flat in a 250mm×250mm molding mold, pre-pressed at 1.0MPa, then hot-pressed at 180℃ for 10min, and left at room temperature for 24h to prepare a fiber substrate. An epoxy resin adhesive was uniformly coated onto one side of the fiber substrate to obtain a first adhesive layer. An inorganic refractory material mixture was then uniformly coated onto the first adhesive layer to obtain an inorganic metal layer. An epoxy resin adhesive was then uniformly coated onto the inorganic metal layer to obtain a second adhesive layer. A wood fiberboard was then covered onto the second adhesive layer as a second substrate, forming a composite board consisting of a first substrate, a first adhesive layer, an inorganic metal layer, a second adhesive layer, and a second substrate. The coating thickness of the inorganic metal layer was 0.3mm, and the coating thickness of both the first and second adhesive layers was 0.3mm.

[0066] The composite board is placed in a hot press for hot pressing; the hot pressing pressure is 1MPa, the hot pressing temperature is 90℃, and the hot pressing time is 1.5min / mm. The hot-pressed composite board is then placed in a flat vulcanizing machine for secondary shaping to obtain a high-strength, lightweight, and environmentally friendly fiber composite board. The vulcanizing time is 5min, the vulcanizing temperature is 45℃, and the vulcanizing pressure is 1MPa.

[0067] S6, Fiberboard post-processing

[0068] After the fiberboard completes the hot pressing process, it is cooled by a scattered cooling method to reduce the internal temperature of the core material to 60°C, resulting in a cooled fiberboard. The cooled fiberboard is then placed in a treatment chamber for humidity conditioning; the placement time is 5 hours; the temperature of the treatment chamber is 70°C and the relative humidity is 75%; after the treatment, the moisture content of the fiberboard is 7%, thus preparing a high-strength, lightweight, and environmentally friendly fiber composite board. Example 3

[0069] This embodiment provides a method for producing high-strength, lightweight, and environmentally friendly fiber composite panels, including the following steps:

[0070] S1. Stacking and storage of timber raw materials, and preparation of wood chips.

[0071] The "three residues" of wood raw materials were stacked and stored for one month. The stack height was 25m and the stack spacing was maintained at 2m. During the stacking process, the moisture content of the wood raw materials was controlled at 13%wt. Then, a drum chipper was used to cut the wood raw materials to obtain wood chips with a size of 30mm×20mm×4mm. Wood chips that exceeded the specified size were further crushed. After further crushing, the small fragments that did not meet the process requirements were screened and burned as fuel. The wood chips were then passed through a magnetic separator to detect and remove metal objects mixed in with the wood chips. The wood chips were then washed by a spiral dewatering washing machine and debarked by an air extrusion process to obtain wood chips.

[0072] S2, Preparation of fiber raw materials

[0073] Monomer fibers were separated from wood chips using a hot grinding method. The centripetal force of the grinding mill was 130 N, the fiber separation time was 16 min, and the grinding time was 60 min. The monomer fibers were then pressure-cooked to soften them, ground, and vacuum-dried at 80℃ for 60 min to obtain fiber raw materials. The cooking temperature was 156℃ and the cooking time was 2.6 h.

[0074] S3. Preparation of superhydrophobic modified fibers

[0075] 30 mL of dodecyltrimethylsiloxane, 25 mL of polydopamine, and 22 mL of isophorone diisocyanate were mixed and dissolved in 500 mL of ethanol to obtain a mixed solution. The fiber raw material was then fully impregnated in the mixed solution for 100 min to obtain superhydrophobic modified fiber.

[0076] S4. Preparation of lightweight inorganic refractory mixture

[0077] 1) Grind diatomaceous earth to a particle size of 16 mm to obtain diatomaceous earth powder;

[0078] 2) Flotation of refractory oxide hollow glass microspheres with a particle size of approximately 5 mm: 100 g of mullite hollow glass microspheres were placed in a beaker, 500 mL of deionized water was added, and the mixture was stirred on a magnetic stirrer at 105 r / min for 35 min, followed by standing for 2 h. The hollow glass microspheres floating on the water surface were then dried at 100℃ under vacuum for 12 h to obtain hollow glass microspheres with a complete particle size. The raw material for the hollow glass microspheres was alumina.

[0079] 3) Preparation of unshaped refractory aggregates: using aluminosilicate clinker, mullite, corundum and silicon carbide as raw materials, ball milling was carried out using a micro ball mill to obtain coarse aggregates with a particle size of 8 mm and fine aggregates with a particle size of 3 mm.

[0080] 4) Mix 100 mg of diatomaceous earth powder, 100 mg of mullite hollow glass microspheres, 50 mg of coarse aggregate and 50 mg of fine aggregate evenly to obtain an inorganic refractory material mixture; mix the inorganic refractory material mixture with 30 g of starch at 110 r / min evenly to prepare a lightweight inorganic refractory material.

[0081] S5. Preparation of high-strength, lightweight, and environmentally friendly fiber composite boards.

[0082] Superhydrophobic modified fibers were laid flat in a molding die, pre-pressed at 1.0 MPa, then hot-pressed at 185°C for 10 min, and left at room temperature for 24 h to prepare a fiber substrate. The fiber substrate served as the first substrate. An epoxy resin adhesive was uniformly coated on one side of the first substrate to obtain a first adhesive layer. An inorganic refractory material mixture was then uniformly coated on the first adhesive layer to obtain an inorganic metal layer. An epoxy resin adhesive was then uniformly coated on the inorganic metal layer to obtain a second adhesive layer. A wood fiberboard was then covered on the second adhesive layer to form a second substrate, resulting in a composite board consisting of a first substrate, a first adhesive layer, an inorganic metal layer, a second adhesive layer, and a second substrate. The coating thickness of the inorganic metal layer was 0.4 mm, and the coating thickness of both the first and second adhesive layers was 0.4 mm.

[0083] The composite board is placed in a hot press for hot pressing; the hot pressing pressure is 1MPa, the hot pressing temperature is 110℃, and the hot pressing time is 1.5min / mm. The hot-pressed composite board is then placed in a flat vulcanizing machine for secondary shaping to obtain a high-strength, lightweight, and environmentally friendly fiber composite board. The vulcanizing time is 8min, the vulcanizing temperature is 60℃, and the vulcanizing pressure is 1.5MPa.

[0084] S6, Fiberboard post-processing

[0085] After the fiberboard completes the hot-pressing process, it is cooled by a dispersed cooling method to reduce the internal temperature of the core material to 65°C, resulting in a cooled fiberboard. The cooled fiberboard is then placed in a treatment chamber for humidity conditioning; the placement time is 5.6 hours; the temperature of the treatment chamber is 74°C and the relative humidity is 80%; after the treatment, the moisture content of the fiberboard is 7.5%, thus preparing a high-strength, lightweight, and environmentally friendly fiber composite board. Example 4

[0086] This embodiment provides a method for producing high-strength, lightweight, and environmentally friendly fiber composite panels, including the following steps:

[0087] S1. Stacking and storage of timber raw materials, and preparation of wood chips.

[0088] The "three residues" of wood raw materials were stacked and stored for 2 months. The stack height was 30m and the stack spacing was maintained at 3m. During the stacking process, the moisture content of the wood raw materials was controlled at 15%wt. Then, a drum chipper was used to cut the wood raw materials to obtain wood chips with a size of 35mm×25mm×5mm. Wood chips that exceeded the specified size were further crushed. After further crushing, the small fragments that did not meet the process requirements were screened and burned as fuel. The wood chips were then passed through a magnetic separator to detect and remove metal objects mixed in with the wood chips. The wood chips were then washed by a spiral dewatering washing machine and debarked by an air extrusion process to obtain wood chips.

[0089] S2, Preparation of fiber raw materials

[0090] The wood chips were separated into monomer fibers by thermal grinding. The centripetal force of the grinding mill was 150N, the fiber separation time was 20min, and the grinding time was 60min. The monomer fibers were then pressure-cooked and softened, ground, and vacuum-dried at 80℃ for 60min to obtain fiber raw materials. The cooking temperature was 160℃ and the cooking time was 3h.

[0091] S3. To prepare superhydrophobic modified fibers, 30 mL of dodecyltrimethylsiloxane, 30 mL of polydopamine, and 22 mL of isophorone diisocyanate were mixed and dissolved in 500 mL of ethanol to obtain a mixed solution. The fiber raw material was fully immersed in the mixed solution for 100 min to obtain superhydrophobic modified fibers.

[0092] S4. Preparation of lightweight inorganic refractory mixture

[0093] 1) Grind diatomaceous earth to a particle size of 20 mm to obtain diatomaceous earth powder;

[0094] 2) Flotation of refractory oxide hollow glass microspheres with a particle size of about 5 mm: 100 g of aluminum spinel hollow glass microspheres were placed in a beaker, 500 mL of deionized water was added, and then the mixture was stirred at 100 r / min for 30 min on a magnetic stirrer and then allowed to stand for 2 h. The hollow glass microspheres floating on the water surface were taken and dried at 100 ℃ for 12 h in a vacuum environment to obtain hollow glass microspheres with complete particle size. The raw material of the hollow glass microspheres is alumina.

[0095] 3) Prepare unshaped refractory aggregates by using aluminosilicate clinker, mullite, corundum and silicon carbide as raw materials, and ball milling them with a micro ball mill to obtain coarse aggregates with a particle size of 10 mm and fine aggregates with a particle size of 5 mm.

[0096] 4) Mix 100 mg of diatomaceous earth powder, 100 mg of refractory oxide hollow glass microspheres, 50 mg of coarse aggregate and 50 mg of fine aggregate evenly to obtain an inorganic refractory material mixture; mix the inorganic refractory material mixture and 30 g of organic binder evenly at 100 r / min to prepare a lightweight inorganic refractory material.

[0097] S5. Preparation of high-strength, lightweight, and environmentally friendly fiber composite boards:

[0098] Superhydrophobic modified fibers were laid flat in a molding die, pre-pressed at 1.0 MPa, then hot-pressed at 185°C for 10 min, and left at room temperature for 24 h to prepare a fiber substrate. The fiber substrate served as the first substrate, and an epoxy resin adhesive was uniformly coated on one side of the first substrate to obtain a first adhesive layer. Then, an inorganic refractory material mixture was uniformly coated on the first adhesive layer to obtain an inorganic metal layer. Then, an epoxy resin adhesive was uniformly coated on the inorganic metal layer to obtain a second adhesive layer. Wood fiberboard was covered on the second adhesive layer to form a second substrate, thus forming a composite board consisting of a first substrate, a first adhesive layer, an inorganic metal layer, a second adhesive layer, and a second substrate. The coating thickness of the inorganic metal layer was 0.5 mm, and the coating thickness of the first and second adhesive layers was 0.5 mm.

[0099] The composite board is placed in a hot press for hot pressing; the hot pressing pressure is 1 MPa, the hot pressing temperature is 130℃, and the hot pressing time is 2 min / mm. The hot-pressed composite board is then placed in a flat vulcanizing machine for secondary shaping to obtain a high-strength, lightweight, environmentally friendly fiber composite board. The vulcanizing time is 10 min, the vulcanizing temperature is 65℃, and the vulcanizing pressure is 2 MPa.

[0100] S6, Fiberboard post-processing

[0101] After the fiberboard completes the hot pressing process, it is cooled by a scattered cooling method to reduce the internal temperature of the core material to 70°C, resulting in a cooled fiberboard. The cooled fiberboard is then placed in a treatment chamber for humidity conditioning, which lasts for 6 hours. The temperature in the treatment chamber is 80°C and the relative humidity is 90%. After the treatment, the moisture content of the fiberboard is 8%, thus producing a high-strength, lightweight, and environmentally friendly fiber composite board.

[0102] Comparative Example 1

[0103] The difference between this comparative example and Example 1 is that polydopamine was not added when preparing the mixed solution in step S3.

[0104] Comparative Example 2

[0105] The difference between this comparative example and Example 1 is that in step S4, when preparing the lightweight inorganic refractory material mixture, the particle size of the prepared amorphous refractory aggregate is coarse aggregate of 5-10 mm.

[0106] Performance testing:

[0107] The high-strength, lightweight, environmentally friendly fiber composite boards prepared in Examples 1-4 and Comparative Examples 1-2 were cut into standard strips. The static bending strength and modulus of elasticity of the prepared composite boards were tested according to GB / T17657-2013, and the limiting oxygen index was tested according to GB / T2406.2-2009. The specific test results are shown in the table below:

[0108] Table 1

[0109] Group Results Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Static bending strength / MPa 43.6 44.1 44.5 44.9 41.5 Elastic modulus / MPa 4201 4450 4681 4819 3890 Limiting oxygen index / % 26.89 27.10 27.42 27.60 26.78

[0110] Data Analysis: The monitoring data of the composite panels from Examples 1-4 and Comparative Examples 1-2 were analyzed and compared. The composite panels prepared in Examples 1-4 all exhibited high static bending strength and modulus of elasticity, and good flame retardant properties, i.e., a high limiting oxygen index. In Comparative Example 1, because the mixed solution was prepared without the addition of polydopamine, the adhesion between the prepared superhydrophobic modified fiber and the epoxy resin and inorganic metal layer was weak, resulting in a decrease in both static bending strength and modulus of elasticity. In Comparative Example 2, the lightweight inorganic refractory material lacked layering of inorganic refractory materials with different particle sizes, leading to a decrease in its limiting oxygen index. Even its static bending strength and modulus of elasticity decreased.

[0111] The above description is merely an example and illustration of the structure of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the structure of the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

[0112] In the description of this specification, references to terms such as "an embodiment," "example," and "specific example" indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0113] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for producing a high-strength, lightweight, environmentally friendly fiber composite board, characterized in that, Includes the following steps: S1. Stacking and storage of timber raw materials and preparation of wood chips: The timber raw materials of "three residues" are stacked and stored for 1-2 months. The stacking height of the timber raw materials is 20-30m and the stacking spacing is maintained at 1-3m. During the stacking process, the moisture content of the timber raw materials is 10%-15%wt. Then, the timber raw materials are cut, magnetically separated, washed with water and debarked to obtain wood chips. S2. Preparation of fiber raw materials: Wood chips are separated into monomer fibers by hot grinding process. The monomer fibers are then softened by pressure cooking, ground to 100-200 mesh, and then dried to prepare fiber raw materials. S3. Preparation of superhydrophobic modified fibers: Dodecyltrimethylsiloxane, polydopamine and isophorone diisocyanate are mixed and dissolved in ethanol to obtain a mixed solution; The fiber raw material was impregnated in the mixed solution for 100 minutes to obtain superhydrophobic modified fiber; S4. Preparation of high-strength lightweight and environmentally friendly fiber composite board: superhydrophobic modified fibers are laid flat in a molding mold, then pre-pressed at 1.0MPa, then hot-pressed at 180-190℃ for 10min, and placed at room temperature for 24h to prepare fiber substrate. S5. Preparation of composite substrate: A fiber substrate is used as the first substrate. An epoxy resin adhesive is uniformly coated on one side of the first substrate to obtain a first adhesive layer. An inorganic refractory material mixture is uniformly coated on the first adhesive layer to obtain an inorganic metal layer. An epoxy resin adhesive is uniformly coated on the inorganic metal layer to obtain a second adhesive layer. A fiber substrate is covered on the second adhesive layer to form a second substrate, thus forming a composite board of first substrate—first adhesive layer—inorganic metal layer—second adhesive layer—second substrate. S6. The composite board is hot-pressed, vulcanized, and cooled in a dispersed manner to obtain a high-strength, lightweight, and environmentally friendly fiber composite board.

2. The method for producing a high-strength, lightweight, environmentally friendly fiber composite board according to claim 1, characterized in that, In step S2, the centripetal force of the refiner in the hot refining process is 100-150N, the fiber separation time is 10-20min, and the refining time is 60min; in the pressurized cooking and softening process, the cooking temperature is 150-160℃ and the cooking time is 2-3h.

3. The method for producing a high-strength, lightweight, environmentally friendly fiber composite board according to claim 1, characterized in that, In step S3, the ratio of the amount of dodecyltrimethylsiloxane, polydopamine, isophorone diisocyanate and anhydrous ethanol is 30mL:15-30g:22mL:500mL.

4. The method for producing a high-strength, lightweight, environmentally friendly fiber composite board according to claim 1, characterized in that, In step S5, the preparation method of lightweight inorganic refractory material includes the following steps: A1. Grind diatomaceous earth to a particle size of 10-20 mm to obtain diatomaceous earth powder; A2. Refractory oxide hollow glass microspheres with a diameter of 5 mm were subjected to flotation to obtain refractory oxide hollow glass microspheres. A3. The unshaped refractory aggregate was ball-milled using a micro ball mill to obtain coarse aggregate with a particle size of 5-10 mm and fine aggregate with a particle size of 0.01-5 mm. A4. Mix diatomaceous earth powder, refractory oxide hollow glass microspheres, coarse aggregate and fine aggregate in a mass ratio of 1:1:0.5:0.5 to obtain an inorganic refractory material mixture; mix the inorganic refractory material mixture and organic binder in a mass ratio of 10:1 to obtain a lightweight inorganic refractory material.

5. The method for producing a high-strength, lightweight, environmentally friendly fiber composite board according to claim 4, characterized in that, In step A2, the refractory oxide hollow glass microspheres are specifically any one of hollow glass microspheres formed from alumina, magnesium oxide, mullite, and aluminum spinel materials, or combinations thereof; the raw materials for the coarse aggregate and fine aggregate are any one of aluminosilicate clinker, mullite, corundum, silicon carbide, and silicon nitride, or combinations thereof.

6. The method for producing a high-strength, lightweight, environmentally friendly fiber composite board according to claim 1, characterized in that, In step S5, the coating thickness of the inorganic metal layer is 0.2-0.5 mm, and the coating thickness of the first adhesive layer and the second adhesive layer is 0.2-0.5 mm.

7. The method for producing a high-strength, lightweight, environmentally friendly fiber composite board according to claim 1, characterized in that, In step S6, the hot pressing process has a hot pressing pressure of 1 MPa, a hot pressing temperature of 90-130℃, and a hot pressing time of 0.5-2 min / mm; the vulcanization process has a vulcanization time of 5-10 min, a vulcanization temperature of 45-65℃, and a vulcanization pressure of 1-2 MPa; the dispersed cooling process specifically involves placing the high-strength, lightweight, environmentally friendly fiber composite board in a treatment chamber for humidity conditioning; wherein the temperature of the treatment chamber is 70-80℃, and the relative humidity of the treatment chamber is 75%-90%; after the treatment, the moisture content of the board is 7%-8%.