A magnesia adhesive plywood, its preparation method and a composite structured wood-based panel

Abstract

The present invention relates to the technical field of building board manufacturing, and specifically provides a magnesia adhesive plywood, a preparation method thereof, and a composite structure artificial board. The magnesia adhesive plywood is composed of 2n + 1 layers of wood veneers and 2n layers of magnesia adhesive layers stacked alternately, where n is a positive integer. Among them, the magnesia adhesive layer is formed by a magnesia adhesive material, and the preparation raw materials of the magnesia adhesive material include: light-burned magnesia powder, anhydrous magnesium chloride, water, fly ash, perlite, silane coupling agent, calcium silicate, phosphoric acid, ferric chloride, and tetraethyl orthosilicate. The wood veneers and the magnesia adhesive layers of the magnesia adhesive plywood provided by the present invention have excellent bonding ability, thereby ensuring that the magnesia adhesive plywood has good stability and mechanical properties. At the same time, the magnesia adhesive plywood has excellent water resistance and is formaldehyde-free and environmentally friendly.

Description

Technical Field

[0001] The present invention relates to the technical field of building board manufacturing, and particularly to a magnesia adhesive plywood, a preparation method thereof, and a composite structure artificial board. Background Art

[0002] Plywood is mainly produced by using fast-growing log and small-diameter wood, slicing them into veneers, and then performing processes such as sizing, assembling, and pressing. Compared with solid wood, plywood has the advantages of stable structure, good physical and mechanical properties, and small variability, and is widely used in many fields such as furniture manufacturing, construction, packaging, interior and exterior decoration, and transportation. The surface wood of plywood is directly exposed, which is easily affected by moisture and fire, resulting in problems such as dimensional changes, rot, and mildew. Even through later decorative processing to improve its fire resistance, wear resistance, and flatness, due to poor adhesion and insufficient bonding strength, its service life is still limited and the cost is relatively high.

[0003] The adhesives used in the artificial board manufacturing industry in China mainly include traditional urea-formaldehyde resin, phenolic resin, and melamine-formaldehyde resin adhesives. Aldehyde adhesives have high strength and fast hardening speed, but aldehyde adhesives have formaldehyde release, pollute the environment, and endanger human health. In addition, the artificial boards made of aldehyde adhesives have poor fire resistance and are prone to causing fire hazards. In recent years, with the increasing demand for artificial boards in various countries in the world, the defects of aldehyde adhesives and their artificial board products have attracted more and more attention.

[0004] In summary, developing a flame-retardant, fire-proof, formaldehyde-free, waterproof, and wear-resistant plywood not only meets the current market demand for high-performance and environmentally friendly materials, but also is an important direction for promoting the transformation and upgrading of the artificial board industry and realizing sustainable development. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems in the prior art to some extent. To this end, an object of the present invention is to provide a magnesia adhesive plywood, a preparation method thereof, and a composite structure artificial board.

[0006] In a first aspect of the present invention, a magnesia adhesive plywood is provided, which is composed of 2n + 1 layers of wood veneers and 2n layers of magnesia adhesive layers stacked alternately, where n is a positive integer. Among them, the magnesia adhesive layer is formed by a magnesia adhesive material, and the preparation raw materials of the magnesia adhesive material include: light-burned magnesia powder, anhydrous magnesium chloride, water, fly ash, perlite, silane coupling agent, calcium silicate, phosphoric acid, ferric chloride, and tetraethyl orthosilicate.

[0007] Specifically, the magnesia adhesive plywood is composed of 3 layers of wood veneers and 2 layers of magnesia adhesive layers stacked alternately. It should be noted that those skilled in the art can select the number of wood veneers and magnesia adhesive layers according to actual needs. For example, the magnesia adhesive plywood has 5 layers of wood veneers and 4 layers of magnesia adhesive layers; another example is that the magnesia adhesive plywood has 7 layers of wood veneers and 6 layers of magnesia adhesive layers; still another example is that the magnesia adhesive plywood has 9 layers of wood veneers and 8 layers of magnesia adhesive layers, etc.

[0008] According to the magnesia adhesive plywood provided by the present invention, magnesia adhesive materials are used to replace aldehyde-based adhesives, and no harmful substances such as formaldehyde will be released during use. By using industrial waste fly ash, not only the purpose of environmental protection and cost reduction is achieved, but also the number of micropores in the final material will increase, the hydration layer thickness will be reduced, and a more dense interpenetrating network structure will be formed. It can interact with the silane coupling agent containing a large number of epoxy groups inside, improving the interfacial bonding strength between the magnesia adhesive material and the surface of the wood veneer. Moreover, the silane coupling agent has strong chemical reaction activity and has a certain coupling effect, and can simultaneously react chemically with other components in the wood and the magnesia adhesive material, thus playing a "bridge" cross-linking role, improving the bonding performance of the magnesia adhesive material, enhancing the mechanical properties of the board, and ensuring that the magnesia adhesive plywood does not delaminate under extremely harsh environments. The main function of perlite is to improve the water and fire resistance. Perlite has stable physical and chemical properties, fine pores, high refractoriness, strong water absorption, and excellent compressive strength, and is a good inorganic lightweight heat-insulating material. The main function of calcium silicate is to improve the internal bonding strength, elastic modulus, static bending strength, and nail-holding force of the composite structure artificial board.

[0009] Phosphoric acid can lower the pH value, improve the interfacial bonding between wood and other materials, inhibit the formation of magnesium hydroxide, protect the crystal phase of magnesia cementitious materials, and improve the stability of magnesia adhesives in water. Ferric chloride transforms the rod-shaped 5-phase structure into a more stable gel-like 5-phase structure. The gel-like structure can fill the micropores of magnesia cementitious materials and wood materials, reducing water infiltration. Tetraethyl orthosilicate has organic and inorganic groups and can undergo interfacial chemical reactions with wood and magnesia adhesives. Tetraethyl orthosilicate can form a colloid with self-hardening adhesive force, forming an elastic hydrophobic layer in the adhesive slurry, coating the magnesia adhesive crystals to a certain extent, and can block the capillary channels between wood and magnesia adhesives, thereby improving the water resistance. In the acidic environment provided by phosphoric acid, the iron ions in ferric chloride can form a complex with phosphate ions, guiding the transformation of the rod-shaped 5-phase structure into a more stable three-dimensional network-like gel-like 5-phase structure. The phosphate group forms a covalent bond with the hydroxyl group of wood cellulose, realizing chemical bonding at the interface between wood and the adhesive layer and inhibiting the formation of magnesium hydroxide. The silanol groups generated by the hydrolysis of tetraethyl orthosilicate under acidic conditions can undergo a condensation reaction with the hydroxyl groups on the wood surface to form a chemical bridge, and achieve organic-inorganic hybridization with the iron ion gel network, forming a composite colloid. Through the seepage effect, a continuous hydrophobic barrier is formed at the interface between wood and the adhesive, blocking the capillary channel transmission. By using phosphoric acid, ferric chloride, and tetraethyl orthosilicate in mutual coordination, the water resistance of magnesia cementitious materials can be significantly exerted, thereby improving the overall water resistance of magnesia adhesive plywood.

[0010] Preferably, the raw materials for preparing the magnesia cementitious material include: 55-65 parts by weight of light-burned magnesia powder, 23-25 parts by weight of anhydrous magnesium chloride, 70-80 parts by weight of water, 30-40 parts by weight of fly ash, 2-5 parts by weight of perlite, 1-5 parts by weight of silane coupling agent, 10-20 parts by weight of calcium silicate, 1-3 parts by weight of phosphoric acid, 1-3 parts by weight of ferric chloride, and 1-3 parts by weight of tetraethyl orthosilicate.

[0011] More preferably, the raw materials for preparing the magnesia cementitious material include: 60 parts by weight of light-burned magnesia powder, 25 parts by weight of anhydrous magnesium chloride, 75 parts by weight of water, 35 parts by weight of fly ash, 3 parts by weight of perlite, 2 parts by weight of silane coupling agent, 15 parts by weight of calcium silicate, 1 part by weight of phosphoric acid, 1 part by weight of ferric chloride, and 1 part by weight of tetraethyl orthosilicate.

[0012] In some embodiments of the present invention, the silane coupling agent is selected from KH560.

[0013] In some embodiments of the present invention, n is a positive integer from 2 to 7.

[0014] In some embodiments of the present invention, the thickness of a single layer of the magnesia adhesive layer is 0.1 mm - 0.3 mm.

[0015] According to the magnesium-based adhesive plywood provided by the present invention, the preparation method of the magnesium-based adhesive material includes:

[0016] (1) Mix the anhydrous magnesium chloride, the fly ash, the perlite and the calcium silicate evenly and then add the water thereto and stir to obtain a brine mixture;

[0017] (2) Add the light-burned magnesium oxide powder to the brine mixture and mix evenly to obtain a mixed material;

[0018] (3) Mix the silane coupling agent, the phosphoric acid, the ferric chloride and the tetraethyl orthosilicate evenly and then add them to the mixed material.

[0019] First, mixing the anhydrous magnesium chloride, fly ash, perlite and calcium silicate evenly and then adding water and stirring can avoid the problem that it is easy to agglomerate and the stirring is uneven when adding fly ash after making the brine of magnesium chloride and water first. The process of adding water will release heat, and the temperature is about 90 degrees. This process needs to be stirred slowly. By slow stirring, the materials can be dissolved sufficiently, and while accelerating the dissolution, the bubbles and voids in the solution are reduced as much as possible. Then add the light-burned magnesium oxide powder to the above brine mixture and mix evenly to keep the mixed material in a thick emulsion or cream state so that it can be mixed evenly with other materials subsequently. Finally, mix the silane coupling agent, phosphoric acid, ferric chloride and tetraethyl orthosilicate evenly and then add them to the mixed material to obtain the magnesium-based adhesive material.

[0020] In some embodiments of the present invention, in step (1), the addition time of the water is not less than 30 min, and the stirring speed does not exceed 20 r / min.

[0021] In some embodiments of the present invention, in step (1), a horizontal mixer is used for stirring. It is a mixer with a dispersing rod, which can effectively avoid the agglomeration of materials and stir evenly.

[0022] In some embodiments of the present invention, in step (2), the addition time of the light-burned magnesium oxide powder to the brine mixture is not more than 30 min. The initial setting time after mixing magnesium oxide and water is generally within 120 minutes. Completing the mixing within 30 minutes can keep the mixed material in a thick emulsion or cream state, which is beneficial to mixing more evenly with other materials subsequently.

[0023] In some embodiments of the present invention, in step (3), the addition time of the silane coupling agent, the phosphoric acid, the ferric chloride and the tetraethyl orthosilicate to the mixed material after being mixed evenly is not more than 10 min. After adding the silane coupling agent, the initial setting time of the magnesium-based adhesive material will be shortened to about 15 minutes. Therefore, it must be mixed evenly quickly before reaching the initial setting.

[0024] In some embodiments of the present invention, the wood veneer is immersed in a 2-5 wt% sodium hydroxide solution for 2-4 hours, then dried to a moisture content of 8-12%, and finally the surface of the dried wood veneer is roughened using a sanding belt with a mesh size of 15-30. The sodium hydroxide solution can remove the extractives and oil components in the wood, release the pores and channels in the wood, contribute to the formation of the bonding surface of the magnesia adhesive material, avoid and reduce the phenomenon of poor curing of the magnesia adhesive material. The roughening treatment can increase the roughness of the core board surface, enabling the magnesia adhesive material to better adhere to the board surface.

[0025] In a second aspect of the present invention, a method for preparing the above-mentioned magnesia adhesive plywood is proposed. It includes:

[0026] Apply the magnesia adhesive material on both sides of the pretreated wood veneer to obtain a sized wood veneer;

[0027] Stack the wood veneers and the sized wood veneers alternately and then cold press them at a pressure of 1.0 MPa - 3.5 MPa for 8 - 28 hours.

[0028] In some embodiments of the present invention, the pretreatment includes: immersing the wood veneer in a 2-5 wt% sodium hydroxide solution for 2-4 hours, then drying to a moisture content of 8-12%, and finally roughening the surface of the dried wood veneer using a sanding belt with a mesh size of 15-30.

[0029] The above-mentioned alternate stacking of wood veneers and sized wood veneers specifically refers to the distribution in the way of alternately stacking in the order of wood veneer - sized wood veneer - wood veneer - sized wood veneer - wood veneer - sized wood veneer -...... - wood veneer, and the outermost layer is a wood veneer. Preferably, the fiber directions of adjacent wood veneers are perpendicular to each other. It should be noted that plywood generally adopts the "odd-layer principle", that is, the number of wood veneers is odd.

[0030] The hydration reaction process of the magnesia adhesive material shows that the hot pressing preparation process is not applicable. During hot pressing, the moisture in the magnesia adhesive material evaporates rapidly, reducing the moisture participating in the hydration reaction, thereby resulting in a decrease in the strength of the product. Therefore, the present invention uses the cold pressing method for pressing. Specifically, the cold pressing method includes: cold pressing the wood veneer and the sized wood veneer at a pressure of 1.0 MPa - 3.5 MPa for 8 - 28 hours at room temperature.

[0031] In some embodiments of the present invention, the core board after pressing is naturally cured at room temperature for 7 days.

[0032] Currently, in order to improve the flame retardancy of plywood, there are mainly the following methods. One is to impregnate veneers with flame retardants or add flame retardants to adhesives, generally including boron-based flame retardants, nano flame retardants, etc. This method has complex processes and high costs. Another is to coat flame retardant coatings on the surface of plywood. The disadvantage of this method is that it is easy to affect the surface decoration quality and the flame retardant effect is average. There is also a method of covering flame retardant materials on the surface of plywood, such as flame retardant gypsum boards. The interfacial bonding strength between the flame retardant material and the plywood in this method is relatively low, and it is easy to cause the two to separate, unable to meet the application requirements of some heavy-load scenarios.

[0033] In view of this, in the third aspect of the present invention, the present invention proposes a composite structure wood-based panel, which includes the above-mentioned magnesia adhesive plywood or the magnesia adhesive plywood prepared by the above method.

[0034] According to the above-mentioned composite structure wood-based panel provided by the present invention, it includes a fireproof layer, a refractory layer, the magnesia adhesive plywood, a refractory layer, and a fireproof layer stacked in sequence;

[0035] The refractory layer is formed by the magnesia adhesive material used to prepare the magnesia adhesive plywood;

[0036] The fireproof layer is formed by a fireproof slurry, and the preparation raw materials of the fireproof slurry include: 55-65 parts by weight of light-burned magnesia powder, 20-25 parts by weight of anhydrous magnesium chloride, 6-8 parts by weight of magnesium sulfate heptahydrate, 55-65 parts by weight of water, 30-40 parts by weight of fly ash, 8-12 parts by weight of polypropylene fiber, 5-8 parts by weight of red mud, and 6-10 parts by weight of aluminum tripolyphosphate.

[0037] According to the above-mentioned composite structure wood-based panel provided by the present invention, the refractory layer is formed by magnesia adhesive material, and at the same time, the above-mentioned fireproof slurry is selected to form the fireproof layer. First of all, the magnesia adhesive material has excellent bonding performance, and it can be well combined with the wood layers (i.e., wood veneers) on both sides of the magnesia adhesive plywood. Secondly, the fireproof slurry selected in the present invention not only has excellent fireproof and mechanical properties, but also has good bonding performance with the refractory layer. A stable bonding interface can be formed between the fireproof layer and the refractory layer, thus ensuring the stability of the entire composite structure wood-based panel and preventing delamination even in extreme environments. Compared with adding adhesives to the fireproof layer as a whole, the present invention uses the refractory layer as the connection layer between the magnesia adhesive plywood and the fireproof layer, which not only significantly reduces the production cost, but also ensures the excellent stability of the composite structure wood-based panel.

[0038] The above-mentioned fireproof slurry used in the present invention has excellent fireproof performance and mechanical properties. Fly ash can increase elasticity and improve the mechanical properties of the final product. Magnesium sulfate heptahydrate can inhibit the phenomenon of "returning brine and frosting". Polypropylene fiber can improve the impact resistance of the fireproof layer, and aluminum tripolyphosphate can inhibit the corrosion of the fireproof layer by the external environment and significantly improve the fire resistance. The main function of adding red mud is to improve the water resistance. Polypropylene fiber, aluminum tripolyphosphate and red mud play a synergistic role in improving the performance of the fireproof layer, and can enhance the impact resistance, compressive resistance, fireproof performance and water resistance.

[0039] Specifically, the ratio of magnesium oxide to magnesium chloride is adjusted, and magnesium sulfate heptahydrate, ferric chloride, tetraethyl orthosilicate, etc. are added at the same time, so as to reasonably control the content of Cl ions and the generation of free Cl ions to reduce moisture absorption and brine return. And by adding fly ash, red mud, polypropylene fiber, etc., the fireproof slurry is toughened and modified, so that the surface wear resistance and waterproofness of the finished product are greatly improved. At the same time, the inorganic components can effectively isolate oxygen at high temperature and prevent the spread of combustion.

[0040] In some embodiments of the present invention, the thickness of the magnesia adhesive plywood is 9 mm - 25 mm.

[0041] In some embodiments of the present invention, the thickness of a single layer of the refractory layer is 1 mm - 7 mm.

[0042] In some embodiments of the present invention, the thickness of a single layer of the fireproof layer is 3 mm - 25 mm.

[0043] In some embodiments of the present invention, the preparation method of the fireproof slurry is as follows:

[0044] (a) Mix the anhydrous magnesium chloride, the fly ash, and the magnesium sulfate heptahydrate evenly, then add the water and stir to obtain a brine material; (b) Add the light-burned magnesium oxide powder to the brine material and mix evenly to obtain an intermediate material; (c) Mix the polypropylene fiber, the red mud, and the aluminum tripolyphosphate evenly and then add them to the intermediate material.

[0045] In some embodiments of the present invention, in step (a), the addition time of the water is not less than 30 min, and the stirring speed does not exceed 20 r / min.

[0046] In some embodiments of the present invention, in step (a), a horizontal mixer is used for stirring. It is a mixer with a dispersing rod, which can effectively avoid material agglomeration and stir evenly.

[0047] In some embodiments of the present invention, in step (b), the time for adding the light-burned magnesia powder to the brine material is not more than 30 minutes. The initial setting time after magnesia and water are mixed is generally within 120 minutes. Completing the mixing within 30 minutes can keep the mixture in a thick emulsion or cream state, which is beneficial for more uniform mixing with other materials in the subsequent process.

[0048] In some embodiments of the present invention, the preparation method of the above composite structure artificial board includes:

[0049] (1) Lay the magnesia adhesive material on the bottom layer of the mold, place the magnesia adhesive plywood on the upper layer of the magnesia adhesive material, and then lay the magnesia adhesive material again on the upper layer of the magnesia adhesive plywood to make the thickness of the magnesia adhesive material on both sides of the magnesia adhesive plywood consistent. Then, cold press at a pressure of 1.2 MPa - 1.6 MPa at room temperature for 6 h - 10 h to obtain a board blank;

[0050] (2) Dry, saw the edges, level and sand the board blank, and perform a roughening treatment using a sand belt with 15 - 30 meshes;

[0051] (3) Lay the fireproof slurry on the bottom layer of the mold, place the board blank treated in step 2 on the upper layer of the fireproof slurry, and then lay the fireproof slurry again on the upper layer of the board blank to make the thickness of the fireproof slurry on both sides of the board blank consistent. Then, cold press at a pressure of 1.0 MPa - 2 MPa at room temperature for 8 h - 48 h;

[0052] (4) Dry, saw the edges, level and sand the board blank obtained in step (3), and naturally cure it at room temperature for 14 days. During the curing period, the surface needs to be sprayed with water to keep the surface moist;

[0053] (5) Perform a second cold pressing on the board blank cured in step (4). The unit pressure of the second cold pressing is 1.0 MPa - 2.0 MPa, the pressing time is 1 h - 3 h, and the temperature is room temperature;

[0054] (6) Dry, bake, saw the edges and sand the board blank after the second cold pressing to obtain a composite structure artificial board.

[0055] The roughening treatment can increase the contact area between the refractory layer and the fireproof layer, and improve the interfacial bonding strength. The reason for keeping the surface moist is that the hydration process is a continuous process and is accompanied by slow heat release. When the water evaporates, it will damage the whiskers of the formed 518 crystals, and the whiskers of the 518 crystals are the key to forming the interpenetrating network structure. Therefore, keeping the surface moist will slow down the water evaporation rate and at the same time make the water inside the material sufficient, which is conducive to the progress of the hydration reaction. The reason for curing for 14 days is that generally, the longer the curing time, the more sufficient the hydration reaction, the more crystal content, and the stronger the mechanical properties of the manufactured board. Based on the fireproof slurry of the present invention, considering factors such as the time cost and the quality of the boards obtained under different curing times, the optimal curing time is 14 days. The main function of the secondary cold pressing is to further increase the density and strength of the board, enhance the internal bonding strength of the board, and improve the stability and durability of the board.

[0056] The present invention has at least the following technical effects:

[0057] (1) There is excellent bonding ability between the wood veneer and the magnesia adhesive layer of the magnesia adhesive plywood provided by the present invention, thus ensuring that the magnesia adhesive plywood has good stability and mechanical properties. At the same time, the magnesia adhesive plywood has excellent water resistance and is formaldehyde-free and environmentally friendly.

[0058] (2) The composite structure artificial board provided by the present invention has excellent stability, fire resistance and mechanical properties. The composite structure artificial board is environmentally friendly and safe, has low production cost, and can maintain stable fireproof and water resistance performance during long-term use. Its physical properties and water resistance can exceed the level of traditional boards, and it can meet the market demand for high-performance and environmentally friendly materials.

[0059] (3) The composite structure artificial board provided by the present invention adopts a five-layer composite structure design with upper and lower symmetry, has simple processes and low costs. The main materials of the two-sided fireproof layer and refractory layer and the adhesive used in the magnesia adhesive plywood are all inorganic magnesia cementitious materials, and aldehyde-based adhesives are not used. The magnesia adhesive plywood and the composite structure artificial board can adopt the cold pressing process during production, do not produce toxic and harmful substances, have no free formaldehyde, save energy, and are green and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0061] Figure 1It is a structural example diagram of the magnesia adhesive plywood provided by the present invention;

[0062] Figure 2 It is a partial structural schematic diagram of the horizontal mixer used for preparing the magnesia adhesive material in the present invention;

[0063] Figure 3 It is a process flow schematic diagram for preparing the magnesia adhesive material provided by the present invention;

[0064] Figure 4 It is a structural example diagram of the composite structure artificial board provided by the present invention;

[0065] Figure 5 It is a process flow schematic diagram for preparing the fireproof slurry provided by the present invention;

[0066] Figure 6 It is a process flow chart for preparing the composite structure artificial board provided by the present invention. Detailed Embodiments

[0067] Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present invention. The present invention will be described below with reference to specific embodiments. It should be noted that these embodiments are merely illustrative and do not limit the present invention in any way.

[0068] Embodiment 1

[0069] This embodiment provides a magnesia adhesive plywood, whose structure can be referred to Figure 1 , and the magnesia adhesive plywood is composed of multiple layers of wood veneers 1 and multiple layers of magnesia adhesive layers 2 stacked alternately. Specifically, the magnesia adhesive plywood has 13 layers of wood veneers 1 and 12 layers of magnesia adhesive layers 2, and the thickness of a single magnesia adhesive layer is 0.2 mm.

[0070] (1) The raw materials for preparing the magnesia adhesive material are as follows:

[0071] 60 parts by weight of light burned magnesia powder, 25 parts by weight of anhydrous magnesium chloride, 75 parts by weight of water, 35 parts by weight of fly ash, 3 parts by weight of perlite, 2 parts by weight of silane coupling agent (KH560), 15 parts by weight of calcium silicate, 1 part by weight of phosphoric acid, 1 part by weight of ferric chloride, and 1 part by weight of tetraethyl orthosilicate.

[0072] (2) The preparation process of the magnesia adhesive material is as follows:

[0073] Step 1. Mix anhydrous magnesium chloride, fly ash, perlite, and calcium silicate evenly with a horizontal mixer equipped with a dispersing rod and then take it out for standby; refer to Figure 2, the horizontal mixer includes a mixing bin 200 and a dispersing rod 300 located inside the mixing bin 200. In the present invention, the mixture 100 is added into the mixing bin 200, and the mixing bin 200 is rotated so that the mixture 100 therein is evenly stirred under the action of the dispersing rod 300.

[0074] Step 2. Add water to the mixture obtained in Step 1 in batches. Heat will be released during this process, and the temperature is about 90 degrees. Stir slowly during this process, and the speed of the planetary mixer does not exceed 20 r / min. This process needs to be controlled for more than 30 minutes.

[0075] Step 3. Gradually add light-burned magnesium oxide to the brine mixture obtained in Step 2 and mix evenly. This process needs to be completed within 30 minutes.

[0076] Step 4. Mix KH560 silane coupling agent, phosphoric acid, ferric chloride, and tetraethyl orthosilicate evenly to obtain a composite modifier, and then add it to the mixture obtained in Step 3 in batches. This process must be completed within 10 minutes to obtain the magnesia-based adhesive material.

[0077] (3) The preparation process of the magnesia-based adhesive plywood is as follows:

[0078] Step 1. Rotary cut the log into wood veneers with a thickness of 1.0 mm - 3.0 mm. Immerse the wood veneers in a 3 wt% sodium hydroxide solution for 3 h, then dry to a moisture content of 8 - 12%, and finally use a 20-mesh sand belt to roughen the surface of the dried wood veneers.

[0079] Step 2. Apply the above magnesia-based adhesive material on both sides of the roughened wood veneers to obtain sized wood veneers. Stack the wood veneers, sized wood veneers, wood veneers,..., sized wood veneers, and wood veneers, and then cold press at room temperature under a pressure of 2 MPa for 15 h.

[0080] Step 3. Naturally cure the above-mentioned pressed magnesia-based adhesive plywood at room temperature for 7 days.

[0081] This embodiment provides a composite structure artificial board, and its specific structure is as Figure 4 shown. It includes a fireproof layer 10, a refractory layer 20, the magnesia-based adhesive plywood 30, a refractory layer 20, and a fireproof layer 10 stacked in sequence. The thickness of the magnesia-based adhesive plywood is 18 mm, the thickness of a single refractory layer is 2 mm, and the thickness of a single fireproof layer is 9 mm.

[0082] (1) The refractory layer uses the magnesia-based adhesive material provided in this embodiment.

[0083] (2) The raw materials for preparing the fireproof slurry used in the fireproof layer are as follows: 60 parts by weight of light-burned magnesium oxide powder, 22 parts by weight of anhydrous magnesium chloride, 7 parts by weight of magnesium sulfate heptahydrate, 60 parts by weight of water, 35 parts by weight of fly ash, 10 parts by weight of polypropylene fiber, 6 parts by weight of red mud, and 8 parts by weight of aluminum tripolyphosphate.

[0084] (3) The preparation process of the fireproof slurry is as follows:

[0085] Step a. Mix anhydrous magnesium chloride, fly ash, and magnesium sulfate heptahydrate evenly and set aside for later use;

[0086] Step b. Add water to the mixture obtained in step a in batches. Heat will be released during this process, and the temperature is about 90 degrees. Stir slowly during this process, and the speed of the planetary mixer does not exceed 20 r / min. This process needs to be controlled for more than 30 minutes;

[0087] Step c. Gradually add the light-burned magnesium oxide powder to the brine mixture obtained in step b and mix evenly. This process needs to be completed within 30 minutes;

[0088] Step d. Mix polypropylene fiber, red mud, and aluminum tripolyphosphate evenly and add them to the mixture obtained in step 3 in batches and mix evenly to obtain the fireproof slurry.

[0089] (4) The preparation process of the composite structure artificial board is as follows:

[0090] Step ①. Lay the magnesia adhesive material on the bottom layer of the mold, place the magnesia adhesive plywood prepared in this embodiment on the upper layer of the magnesia adhesive material, and then lay the magnesia adhesive material again on the upper layer of the magnesia adhesive plywood to make the thickness of the magnesia adhesive material on both sides of the magnesia adhesive plywood consistent. Then, cold press at room temperature under a pressure of 1.4 MPa for 8 h to obtain a board blank;

[0091] Step ②. Dry, saw the edges, level and sand the board blank, and perform a roughening treatment using a 20-mesh sanding belt;

[0092] Step ③. Lay the fireproof slurry prepared above on the bottom layer of the mold, place the board blank processed in step ② on the upper layer of the fireproof slurry, and then lay the fireproof slurry again on the upper layer of the board blank to make the thickness of the fireproof slurry on both sides of the board blank consistent. Then, cold press at room temperature under a pressure of 1.5 MPa for 25 h;

[0093] Step ④. Dry, saw the edges, level and sand the board blank obtained in step ③, and cure it naturally at room temperature for 14 days. During the curing period, the surface needs to be sprayed with water to keep the surface moist;

[0094] Step ⑤. Perform a secondary cold pressing on the board blank cured in step ④ at room temperature, with a unit pressure of 1.5 MPa and a pressing time of 2 h;

[0095] Step ⑥. Dry, bake, saw the edges, and sand the slab after the above-mentioned secondary cold pressing to obtain a composite structure artificial board.

[0096] Example 2

[0097] This example provides a magnesia adhesive plywood. The difference between Example 2 and Example 1 is as follows:

[0098] (1) The raw materials for preparing the magnesia adhesive material are as follows:

[0099] 60 parts by weight of light-burned magnesia powder, 25 parts by weight of anhydrous magnesium chloride, 75 parts by weight of water, 35 parts by weight of fly ash, 3 parts by weight of perlite, 2 parts by weight of silane coupling agent (KH560), 15 parts by weight of calcium silicate, 2 parts by weight of phosphoric acid, 2 parts by weight of ferric chloride, and 2 parts by weight of tetraethyl orthosilicate.

[0100] Comparative Example 1

[0101] This comparative example provides a magnesia adhesive plywood. The difference between Comparative Example 1 and Example 1 is as follows:

[0102] (1) The raw materials for preparing the magnesia adhesive material are as follows:

[0103] 60 parts by weight of light-burned magnesia powder, 25 parts by weight of anhydrous magnesium chloride, 75 parts by weight of water, 35 parts by weight of fly ash, 3 parts by weight of perlite, 2 parts by weight of silane coupling agent (KH560), and 15 parts by weight of calcium silicate.

[0104] This comparative example provides a composite structure artificial board. The difference between Comparative Example 1 and Example 1 is as follows:

[0105] The refractory layer used in the composite structure artificial board of Comparative Example 1 is the magnesia adhesive material prepared in Comparative Example 1, and the magnesia adhesive plywood uses the magnesia adhesive plywood prepared in Comparative Example 1.

[0106] Comparative Example 2

[0107] This comparative example provides a magnesia adhesive plywood. The difference between Comparative Example 2 and Example 1 is as follows:

[0108] (1) The raw materials for preparing the magnesia adhesive material are as follows:

[0109] 60 parts by weight of light-burned magnesia powder, 25 parts by weight of anhydrous magnesium chloride, 75 parts by weight of water, 35 parts by weight of fly ash, 3 parts by weight of perlite, 2 parts by weight of silane coupling agent (KH560), 15 parts by weight of calcium silicate, and 3 parts by weight of phosphoric acid.

[0110] Comparative Example 3

[0111] This comparative example provides a magnesia adhesive plywood. The difference between Comparative Example 3 and Example 1 is as follows:

[0112] (1)The raw materials for preparing the magnesia adhesive material are as follows:

[0113] 60 parts by weight of light-burned magnesia powder, 25 parts by weight of anhydrous magnesium chloride, 75 parts by weight of water, 35 parts by weight of fly ash, 3 parts by weight of perlite, 2 parts by weight of silane coupling agent (KH560), 15 parts by weight of calcium silicate, and 3 parts by weight of ferric chloride.

[0114] Comparative Example 4

[0115] This comparative example provides a magnesia adhesive plywood. The difference between Comparative Example 4 and Example 1 is:

[0116] (1)The raw materials for preparing the magnesia adhesive material are as follows:

[0117] 60 parts by weight of light-burned magnesia powder, 25 parts by weight of anhydrous magnesium chloride, 75 parts by weight of water, 35 parts by weight of fly ash, 3 parts by weight of perlite, 2 parts by weight of silane coupling agent (KH560), 15 parts by weight of calcium silicate, and 3 parts by weight of tetraethyl orthosilicate.

[0118] Comparative Example 5

[0119] This comparative example provides a magnesia adhesive plywood. The difference between Comparative Example 5 and Example 1 is:

[0120] (1)The raw materials for preparing the magnesia adhesive material are as follows:

[0121] 60 parts by weight of light-burned magnesia powder, 25 parts by weight of anhydrous magnesium chloride, 75 parts by weight of water, 35 parts by weight of fly ash, 3 parts by weight of perlite, 2 parts by weight of silane coupling agent (KH560), 15 parts by weight of calcium silicate, 1 part by weight of phosphoric acid, and 2 parts by weight of ferric chloride.

[0122] Comparative Example 6

[0123] This comparative example provides a magnesia adhesive plywood. The difference between Comparative Example 6 and Example 1 is:

[0124] (1)The raw materials for preparing the magnesia adhesive material are as follows:

[0125] 60 parts by weight of light-burned magnesia powder, 25 parts by weight of anhydrous magnesium chloride, 75 parts by weight of water, 35 parts by weight of fly ash, 3 parts by weight of perlite, 2 parts by weight of silane coupling agent (KH560), 15 parts by weight of calcium silicate, 2 parts by weight of phosphoric acid, and 1 part by weight of tetraethyl orthosilicate.

[0126] Comparative Example 7

[0127] This comparative example provides a magnesia adhesive plywood. The difference between Comparative Example 7 and Example 1 is:

[0128] (1)The raw materials for preparing the magnesia adhesive material are as follows:

[0129] 60 parts by weight of light burned magnesium oxide powder, 25 parts by weight of anhydrous magnesium chloride, 75 parts by weight of water, 35 parts by weight of fly ash, 3 parts by weight of perlite, 2 parts by weight of silane coupling agent (KH560), 15 parts by weight of calcium silicate, 1 part by weight of ferric chloride and 2 parts by weight of tetraethyl orthosilicate.

[0130] Comparative Example 8

[0131] This comparative example provides a magnesium-based adhesive plywood, and its preparation raw materials and preparation process are the same as those of Example 1.

[0132] This comparative example provides a composite structure artificial board. The difference between Comparative Example 8 and Example 1 is:

[0133] (2) The preparation raw materials of the fireproof slurry used in the fireproof layer are as follows: 60 parts by weight of light burned magnesium oxide powder, 22 parts by weight of anhydrous magnesium chloride, 7 parts by weight of magnesium sulfate heptahydrate, 60 parts by weight of water, 35 parts by weight of fly ash, and 10 parts by weight of polypropylene fiber.

[0134] Comparative Example 9

[0135] This comparative example provides a magnesium-based adhesive plywood, and its preparation raw materials and preparation process are the same as those of Example 1.

[0136] This comparative example provides a composite structure artificial board. The difference between Comparative Example 9 and Example 1 is:

[0137] (2) The preparation raw materials of the fireproof slurry used in the fireproof layer are as follows: 60 parts by weight of light burned magnesium oxide powder, 22 parts by weight of anhydrous magnesium chloride, 7 parts by weight of magnesium sulfate heptahydrate, 60 parts by weight of water, 35 parts by weight of fly ash, 10 parts by weight of polypropylene fiber, and 14 parts by weight of red mud.

[0138] Comparative Example 10

[0139] This comparative example provides a magnesium-based adhesive plywood, and its preparation raw materials and preparation process are the same as those of Example 1.

[0140] This comparative example provides a composite structure artificial board. The difference between Comparative Example 10 and Example 1 is:

[0141] (2) The preparation raw materials of the fireproof slurry used in the fireproof layer are as follows: 60 parts by weight of light burned magnesium oxide powder, 22 parts by weight of anhydrous magnesium chloride, 7 parts by weight of magnesium sulfate heptahydrate, 60 parts by weight of water, 35 parts by weight of fly ash, 10 parts by weight of polypropylene fiber, and 14 parts by weight of aluminum tripolyphosphate.

[0142] Comparative Example 11

[0143] This comparative example provides a magnesium-based adhesive plywood, and its preparation raw materials and preparation process are the same as those of Example 1.

[0144] The comparative example provides a composite structural wood-based panel. The difference between Comparative Example 11 and Example 1 is as follows:

[0145] The composite structural wood-based panel of Comparative Example 11 has no fire-resistant layer, only a fire-proof layer, that is, a fire-proof layer is prepared on both sides of the magnesia adhesive plywood. The raw materials used in the specific fire-proof layer and the preparation process are the same as those in Example 1.

[0146] Comparative Example 12

[0147] This comparative example provides a magnesia adhesive plywood, and its preparation raw materials and preparation process are the same as those in Example 1.

[0148] The comparative example provides a composite structural wood-based panel. The difference between Comparative Example 12 and Example 1 is as follows:

[0149] The composite structural wood-based panel of Comparative Example 12 has only a fire-resistant layer.

[0150] Comparative Example 13

[0151] This comparative example provides a magnesia adhesive plywood. The difference between Comparative Example 13 and Example 1 is as follows:

[0152] The wood veneer used in Comparative Example 13 is not subjected to napping treatment.

[0153] The comparative example provides a composite structural wood-based panel. The difference between Comparative Example 13 and Example 1 is as follows: (4) The board blank in step ② during the preparation process of the composite structural wood-based panel is not subjected to napping treatment.

[0154] Comparative Example 14

[0155] This comparative example provides a magnesia adhesive plywood. The difference between Comparative Example 14 and Example 1 is as follows:

[0156] The wood veneer used in Comparative Example 14 is subjected to napping treatment with a 40-mesh sanding belt.

[0157] The comparative example provides a composite structural wood-based panel. The difference between Comparative Example 14 and Example 1 is as follows: (4) The board blank in step ② during the preparation process of the composite structural wood-based panel is subjected to napping treatment with a 40-mesh sanding belt.

[0158] Comparative Example 15

[0159] This comparative example provides a magnesia adhesive plywood. The difference between Comparative Example 15 and Example 1 is as follows:

[0160] The wood veneer used in Comparative Example 15 is subjected to napping treatment with a 60-mesh sanding belt.

[0161] The comparative example provides a composite structural wood-based panel. The difference between Comparative Example 15 and Example 1 is: (4) The slab in step ② during the preparation process of the composite structural wood-based panel is subjected to sanding treatment with a 60-mesh sand belt.

[0162] To verify the performance of the magnesia-based adhesive plywood and the composite structural wood-based panel of the present invention, tests were carried out on them, as follows:

[0163] (1) The water resistance of the magnesia-based adhesive plywood provided in Examples 1-2 and Comparative Examples 1-7 was tested.

[0164] Immersion peeling length:

[0165] Method: In accordance with 4.19 in "Test Methods for Physical and Chemical Properties of Wood-Based Panels and Decorative Wood-Based Panels" GB / T 17657-2022, the test specimens were immersed in boiling water for 4 h, taken out and placed in a drying oven at (63 ± 3) °C for 20 h, then the test specimens were put into boiling water again for 4 h, taken out and then placed in a drying oven at (63 ± 3) °C for 3 h. Carefully observe whether there is peeling and delamination between the adhesive layers of the test specimens or between the veneer layer and the substrate layer. Use a steel ruler to measure the length of the peeled or delaminated part of each side of each adhesive layer of the test specimens respectively.

[0166] Standard: According to the requirements of "General Plywood" GB / T 9846—2015, the cumulative peeling length of each side of the same adhesive layer of each test specimen shall not exceed 25 mm.

[0167] 24-hour water absorption rate:

[0168] Method: In accordance with 4.9 in "Test Methods for Physical and Chemical Properties of Wood-Based Panels and Decorative Wood-Based Panels" GB / T 17657-2022, after the test specimens were soaked for 24 h ± 15 min, the test specimens were taken out, and the surface moisture was wiped off with a wet rag, and weighing was completed within 10 min. Calculate and determine the ratio of the mass difference of the test specimens before and after soaking in water for 24 h to the mass of the test specimens before soaking in water.

[0169] The test results of the water resistance of the magnesia-based adhesive plywood provided in Examples 1-2 and Comparative Examples 1-7 are shown in Table 1.

[0170] Table 1

[0171]

[0172] As can be seen from Table 1, adding phosphoric acid, ferric chloride, and tetraethyl orthosilicate to the magnesia-based adhesive material at the same time can significantly improve the water resistance of the magnesia-based adhesive plywood.

[0173] (2) The boiling water resistance of the magnesia-based adhesive plywood and the composite structural wood-based panel provided in Example 1 and Comparative Example 1 was tested.

[0174] The composite structure wood-based panel can be used as building decoration materials. Generally, the sides of the panel are not edge-sealed, and its working environment may be a humid environment. Therefore, it is necessary to consider the influence of the water resistance of the panel core of the composite structure wood-based panel on the overall water resistance of the composite panel. Thus, a boiling water resistance test is carried out, and the specific test is as follows:

[0175] Method: Refer to 4.52 in "Test Methods for Physical and Chemical Properties of Wood-based Panels and Decorative Wood-based Panels" GB / T 17657-2022 to determine the increase in mass and thickness of each specimen after being immersed in boiling water for 2 h, as well as the appearance changes such as bubbling or delamination.

[0176] Evaluate the change level of the specimen according to the surface quality and edge quality, and rate the surface quality.

[0177] Surface quality rating:

[0178] Grade 5: No change; Grade 4: Slight change in gloss and / or color at a certain angle; Grade 3: Moderate change in gloss and / or color; Grade 2: Obvious change in gloss and / or color; Grade 1: Bubbling and / or delamination.

[0179] Edge quality rating:

[0180] Grade 5: No obvious change; Grade 4: Slight edge cracks visible to the naked eye; Grade 3: Medium edge cracks; Grade 2: Severe edge cracks; Grade 1: Core layer delamination.

[0181] The test results of the boiling water resistance of the magnesia adhesive plywood and the composite structure wood-based panel provided in Example 1 and Comparative Example 1 are shown in Table 2.

[0182] Table 2

[0183]

[0184] It can be seen from Table 2 that the magnesia adhesive plywood and the composite structure wood-based panel of the present invention both have a certain boiling water resistance.

[0185] (3) After pressing the fireproof slurries of Example 1 and Comparative Examples 8-10, test their water resistance and mechanical properties.

[0186] The specific pressing process is as follows:

[0187] Step 1. Mechanically spread the fireproof slurry evenly into the mold, and control its spreading thickness to be about 10 mm.

[0188] Step 2. Send the mold into the press, and cold press it at a pressure of 1.5 MPa at room temperature for 12 h.

[0189] Step 3. Dry, saw the edges, level and sand the board blank, and cure it naturally at room temperature for 14 days. During the curing period, spray water on the surface to keep the surface moist.

[0190] Step 4. Subject the cured slab to secondary cold pressing at room temperature with a unit pressure of 1.5 MPa and a pressing time of 2 h;

[0191] Step 5. Dry, bake, saw the edges, and sand the slab after the above-mentioned secondary cold pressing.

[0192] Softening coefficient (water resistance): The softening coefficient α is the ratio of the compressive strength R of the fireproof layer cured in air for 28 days α to the compressive strength R of the fireproof layer cured in air for 28 days and then immersed in water for 28 days. α = R w / R w / R α .

[0193] Flexural strength and modulus of elasticity (mechanical properties): For wood-based panels and veneered wood-based panels, in accordance with 4.7 of GB / T 17657-2022, the flexural strength is the ratio of the bending moment to the section modulus of resistance to bending when the test piece is under the maximum load; the modulus of elasticity is the ratio of the stress generated by the load to the strain within the elastic limit of the material.

[0194] The flexural strength and modulus of elasticity in three-point bending are measured by applying a load at the middle of the test piece supported at two points. Record the maximum load.

[0195] The test results of the mechanical properties and water resistance of the fireproof slurry pressed plates in Example 1 and Comparative Examples 8-10 are shown in Table 3.

[0196] Table 3

[0197]

[0198] As can be seen from Table 3, adding red mud to the fireproof slurry will significantly enhance the water resistance, and adding aluminum tripolyphosphate will significantly enhance the mechanical properties. After balancing the addition amounts of the two, the composite structural wood-based panel of the present invention can simultaneously have excellent water resistance and mechanical properties.

[0199] (4) Test the impact resistance, abrasion resistance, and flame retardancy of the magnesia adhesive plywood in Example 1, the composite structural wood-based panel, and the composite structural wood-based panels in Comparative Examples 11-12.

[0200] Gluing strength: It refers to the ability of the glue layer to resist tensile failure, usually expressed by the maximum tensile force per unit area. According to the GB / T 17657-2022 standard, the test of gluing strength is to cause shear failure of the glue layer of the test piece through a tensile load, so as to determine the gluing quality of the composite structural wood-based panel.

[0201] Impact deformation: According to "Test methods for wood structures - Soft body impact test for wood frame walls" EN 596:1995, a heavy object is impacted on the specimen panel under manual force, and the maximum residual deformation is recorded.

[0202] Wear value: According to 4.47 in "Test methods for physical and chemical properties of wood-based panels and veneered wood-based panels" GB / T 17657-2022, it is the amount of surface loss after the product surface and a pair of grinding wheels with abrasive cloth are rubbed against each other for a certain number of revolutions.

[0203] Flame retardant time: According to "Test method for flammability of building materials" GB / T 8626-2007, a small flame is directly impacted on the vertically placed specimen, and the time when the dripping ignites the filter paper is recorded.

[0204] Table 4

[0205]

[0206] As can be seen from Table 4, the composite structure wood-based panel of the present invention has excellent flame retardant performance, and the bonding strength between the fireproof layer and the fire-resistant layer is strong. The composite structure wood-based panel has excellent stability, wear resistance and impact resistance.

[0207] (5) The bonding strength between the wood veneer and the magnesia adhesive layer, between the magnesia adhesive plywood and the fire-resistant layer, and between the fire-resistant layer and the fireproof layer of the magnesia adhesive plywood in Example 1 and Comparative Examples 13-15.

[0208] The specific results are shown in Table 5.

[0209] Table 5

[0210]

[0211] As can be seen from Table 5, by roughening the wood veneer and the fire-resistant layer with a certain strength, the bonding force between each layer can be significantly improved.

[0212] (6) Mechanical property tests were carried out on the composite structure wood-based panel prepared in Example 1, and the specific results are shown in Table 6.

[0213] Table 6

[0214]

[0215] The fire protection grade of the composite structure wood-based panel prepared in Example 1 was tested, and the specific results are shown in Table 7.

[0216]

[0217] The fire protection grade meets the requirements of Class B1.

[0218] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A composite structure artificial board, characterized in that: It includes a fireproof layer, a fire-resistant layer, a magnesium adhesive plywood, a fire-resistant layer, and a fireproof layer stacked in sequence; The magnesium adhesive plywood is composed of 2n+1 layers of wood veneer and 2n layers of magnesium adhesive layers stacked alternately, where n is a positive integer, wherein the magnesium adhesive layer is formed of a magnesium adhesive material, and the raw materials for preparing the magnesium adhesive material include: light-burned magnesium oxide powder, anhydrous magnesium chloride, water, fly ash, perlite, silane coupling agent, calcium silicate, phosphoric acid, ferric chloride and ethyl orthosilicate; The fire-resistant layer is formed by the magnesium adhesive material used to prepare the magnesium adhesive plywood; The fireproof layer is formed by a fireproof slurry, and the raw materials for preparing the fireproof slurry include: 55-65 parts by weight of light-burned magnesium oxide powder, 20-25 parts by weight of anhydrous magnesium chloride, 6-8 parts by weight of magnesium sulfate heptahydrate, 55-65 parts by weight of water, 30-40 parts by weight of fly ash, 8-12 parts by weight of polypropylene fiber, 5-8 parts by weight of red mud, and 6-10 parts by weight of aluminum tripolyphosphate; The raw materials for preparing the magnesium adhesive material include: 55-65 parts by weight of light-burned magnesium oxide powder, 23-25 ​​parts by weight of anhydrous magnesium chloride, 70-80 parts by weight of water, 30-40 parts by weight of fly ash, 2-5 parts by weight of perlite, 1-5 parts by weight of silane coupling agent, 10-20 parts by weight of calcium silicate, 1-3 parts by weight of phosphoric acid, 1-3 parts by weight of ferric chloride and 1-3 parts by weight of tetraethyl orthosilicate.

2. The composite structure artificial board according to claim 1, characterized in that: n is a positive integer from 2 to 7; And / or, the thickness of the single layer of magnesium adhesive layer is 0.1 mm-0.3 mm.

3. The composite structure artificial board according to claim 1 or 2, characterized in that: The preparation method of the magnesium adhesive material comprises: (1) uniformly mixing the anhydrous magnesium chloride, the fly ash, the perlite and the calcium silicate, adding the water and stirring to obtain a brine mixture; (2) adding the light-burned magnesium oxide powder into the brine mixture and mixing them evenly to obtain a mixture; (3) The silane coupling agent, the phosphoric acid, the ferric chloride and the tetraethyl orthosilicate are mixed evenly and then added to the mixture.

4. The composite structure artificial board according to claim 3, characterized in that: In step (1), the water is added for no less than 30 minutes, and the stirring speed does not exceed 20 r / min; and / or, in step (2), the light-burned magnesium oxide powder is added to the brine mixture for no more than 30 minutes; And / or, in step (3), the silane coupling agent, the phosphoric acid, the ferric chloride and the tetraethyl orthosilicate are mixed evenly and then added to the mixture for no more than 10 minutes.

5. The composite structure artificial board according to claim 1, characterized in that: The method for preparing the magnesium adhesive plywood comprises: Applying magnesium adhesive material to both sides of the pretreated wood veneer to obtain a glued wood veneer; The wooden veneers and the glued wooden veneers are alternately stacked and then cold pressed at a pressure of 1.0 MPa to 3.5 MPa for 8 hours to 28 hours.

6. The composite structure artificial board according to claim 5, characterized in that: The pretreatment includes: soaking the wooden veneer in a 2-5wt% sodium hydroxide solution for 2h-4h, drying it to a moisture content of 8-12%, and finally roughening the surface of the dried wooden veneer using a 15-30 mesh sanding belt.

7. The composite structure artificial board according to claim 1 or 2, characterized in that: The thickness of the magnesium adhesive plywood is 9mm-25mm; And / or, the thickness of the single-layer refractory layer is 1 mm to 7 mm; And / or, the thickness of the single-layer fireproof layer is 3mm-25mm.

8. The composite structure artificial board according to claim 1 or 2, characterized in that: The preparation method of the fireproof slurry is as follows: The anhydrous magnesium chloride, the fly ash and the magnesium sulfate heptahydrate are uniformly mixed, and then the water is added and stirred to obtain a brine material; Adding the light-burned magnesium oxide powder into the brine material and mixing evenly to obtain an intermediate material; The polypropylene fiber, the red mud and the aluminum tripolyphosphate are uniformly mixed and then added into the intermediate material.

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