Long-acting flame-retardant anti-deformation composite board as well as preparation method and application thereof

Abstract

The invention provides a long-acting flame-retardant anti-deformation composite board as well as a preparation method and application thereof, and relates to the technical field of composite boards. The long-acting flame-retardant deformation-resistant composite board comprises crushed aggregate layers, bridging layers and core plywood, and the crushed aggregate layers are glued to the upper surface and the lower surface of the core plywood through the bridging layers; the crushed aggregate layer comprises crushed biomass and a magnesium adhesive containing carbon quantum dots; the bridging layer comprises a magnesium adhesive containing the carbon quantum dots, and the magnesium adhesive containing the carbon quantum dots comprises the following components in percentage by weight: 25 to 35 percent of magnesium chloride, 18 to 20 percent of water, 0.5 to 2 percent of the carbon quantum dots, 45 to 55 percent of magnesium oxide and 0.5 to 3 percent of layered nano-metakaolin, and the magnesium adhesive containing the carbon quantum dots comprises the following components in percentage by weight: 25 to 35 percent of magnesium chloride, 18 to 20 percent of water, 0.5 to 2 percent of the carbon quantum dots, 45 to 55 percent of magnesium oxide and 0.5 to 3 percent of layered nano-metakaolin. The plate provided by the invention is high in surface flatness, good in dimensional stability and strong in flame retardant property.

Description

Technical Field

[0001] The present invention relates to the technical field of composite board materials, and in particular to a long-lasting flame-retardant and deformation-resistant composite board material and a preparation method and application thereof. Background Art

[0002] Ordinary plywood, blockboard and particleboard are made from the residues of wood and bamboo processing. They are eco-friendly, carbon storage and carbon fixation, and are favored by the market and consumers. However, such single-category products often have shortcomings such as poor surface flatness, poor dimensional stability, easy surface cracking, and low mechanical strength. At the same time, the current artificial boards still use urea-formaldehyde resin, phenolic resin, melamine formaldehyde resin and other resins as the main adhesives, and the board materials are more or less added with the chemical hazard "formaldehyde", and the environmental safety performance is difficult to meet the current consumers' increasingly enhanced new environmental protection needs.

[0003] Composite panels are a type of product derived from the market in recent years. They are mainly made of fine wood particles or fine fibers as the surface, and traditional plywood, blockboard and oriented strand board as the base material (core material). Composite panels prepared by composite molding have the advantages of smooth surface, surface crack resistance, good processing performance, and high comprehensive cost performance. However, since the core board used is often ordinary particle board, ordinary plywood and oriented strand board, there are potential formaldehyde release risks, easy moisture absorption and deformation, and lack of functionality. In particular, the sandwich structure of this "sandwich", the flammability of the surface and the lack of flame retardant treatment of the core layer will lead to the "chimney effect" of the terminal product under high temperature heat source or fire environment. The fire safety hazards of this type of product are more dangerous than traditional homogeneous materials, and the hidden dangers are larger and more severe. Therefore, the lack of flame retardant function of composite panels poses a great threat to the demand for sound market products and product safety.

[0004] Based on composite boards, related products with improved performance such as no formaldehyde addition and flame retardant functions have yet to be developed at home and abroad. Ordinary composite boards are often difficult to meet consumers' new demands for functionality, high performance, and long-lasting durability in some public places, high-performance homes and furniture, and other environments with stringent performance requirements.

[0005] The existing composite board materials still use traditional artificial boards made of organic glue containing formaldehyde (urea-formaldehyde resin glue, melamine-modified urea-formaldehyde resin glue, etc.), which have potential formaldehyde addition and release pollution, and the products are flammable and have high fire risks; while the current formaldehyde-free organic glue (polyurethane adhesive, isocyanate adhesive, soy protein glue, etc.) has overcome the defects of formaldehyde addition, but still has problems such as high cost and insufficient functionality of adhesives, such as high requirements for spray protection of spraying liquid during the production of isocyanate glue (the leakage of glue spray can easily cause potential toxic hazards to the human body), and high smoke toxicity in the fire environment when the product is used; and the artificial board products prepared by soy protein glue are prone to mold and stink in the process of humidity and long-term application, causing severe harm to public places and indoor environments. Therefore, it is of great urgency to develop a composite board without formaldehyde addition, flame retardant and fireproof, multifunctional and long-lasting, which is in line with the current development trend of green and environmentally friendly building materials.

[0006] Chinese patent application 202211050784.X discloses a flame-retardant solid wood composite floor and a production method thereof, wherein the flame-retardant solid wood composite floor comprises a substrate layer, a panel layer arranged on one side of the substrate layer and a bottom plate layer arranged on the other side of the substrate layer, and the layers are bonded by flame-retardant adhesive; the substrate layer is a composite substrate layer formed by bonding a number of single boards by flame-retardant adhesive; the bottom plate layer is a single board; the panel layer is a single board that absorbs flame retardant. According to its description and embodiments, it can be known that the flame-retardant adhesive used is a mixture of compound flame-retardant powder and melamine adhesive, which belongs to the category of organic adhesives. The density of the organic adhesive layer is often low, and the high temperature hot pressing causes uneven thermal effect, so the dimensional stability of this type of composite board is generally poor; at the same time, because the panel layer is a single board that absorbs organic flame retardant, the composite board has strong hygroscopicity and the absorption thickness expansion rate is often high, which is not conducive to the composite board having the requirements of flame retardancy, high strength, high dimensional stability, and low water absorption thickness expansion rate.

[0007] Chinese patent application 202310733384.7 discloses a water-resistant magnesium oxychloride inorganic adhesive for plywood and a preparation method thereof. The inorganic adhesive is a mixture of magnesium oxide, anhydrous magnesium chloride, water, and a modifier; the modifier is composed of phosphoric acid, nano-silicon dioxide, calcium chloride, isocyanate, and EVA emulsion. The types of modifiers are complex, and the water-resistant inorganic adhesive is mainly achieved by filling nano-silicon dioxide particles and organic sealing of isocyanate and EVA emulsion. The water resistance needs to be further improved. Summary of the invention

[0008] In view of the above analysis, the present invention aims to provide a long-lasting flame-retardant and deformation-resistant composite board material and its preparation method and application, so as to meet the requirements of green environmental protection, long-lasting flame retardancy and high comprehensive cost performance of the board material, solve the problems of complex preparation process, improve the performance of the plywood after facing, and facilitate the quality assurance of the subsequent coating of adhesive paper and membrane materials on the surface of the faced plywood.

[0009] The purpose of the present invention is mainly achieved through the following technical solutions:

[0010] In the first aspect, the present invention provides a long-lasting flame retardant and deformation-resistant composite board, comprising a crushed aggregate layer, a bridging layer and a core plywood, wherein the crushed aggregate layer is glued to the upper surface and the lower surface of the core plywood through the bridging layer; the crushed aggregate layer comprises biomass crushed materials and magnesium oxychloride adhesive containing carbon quantum dots; the bridging layer comprises magnesium adhesive containing carbon quantum dots, wherein:

[0011] Based on the total weight of the magnesium adhesive containing carbon quantum dots, the magnesium adhesive containing carbon quantum dots includes: 25wt.%-35wt.% magnesium chloride, 18wt.%-20wt.% water, 0.5wt.%-2wt.% carbon quantum dots, 45wt.%-55wt.% magnesium oxide, and 0.5wt.%-3wt.% layered nano-metakaolin.

[0012] Preferably, in the aggregate layer, the mass ratio of the biomass fragments to the magnesium adhesive containing carbon quantum dots is (0.5-2.0):1.

[0013] Preferably, the biomass fragments include at least one of straw, wood shavings and reeds.

[0014] Preferably, the particle size of the biomass fragments is 10-32 meshes.

[0015] Preferably, in the magnesium adhesive containing carbon quantum dots, the surface of the carbon quantum dots has surface functional groups, and the surface functional groups include at least one of a phosphate group, an amino group, and a sulfate group.

[0016] Preferably, the particle size of the layered nano-metakaolin is 200-500 nm, and the aspect ratio is (4-6):1.

[0017] Preferably, the thickness of the crushed aggregate layer is 1-2 mm.

[0018] Preferably, the core plywood is formed by laminating and gluing a plurality of veneers with an inorganic adhesive.

[0019] Preferably, the veneer is a eucalyptus veneer.

[0020] Preferably, the thickness of the core plywood is 14-16 mm; the number of veneer layers in the core plywood is 7-9.

[0021] Preferably, the inorganic adhesive includes at least one of a magnesium adhesive, a silicon adhesive, and a magnesium-silicon mixed adhesive.

[0022] Preferably, the inorganic adhesive is the magnesium adhesive containing carbon quantum dots.

[0023] In a second aspect, the present invention provides a method for preparing the composite board, comprising the following steps:

[0024] Step 1: Apply a bridging layer to the upper and lower surfaces of the core plywood;

[0025] Step 2: laying a biomass mixture containing biomass crushed materials and a magnesium adhesive containing carbon quantum dots on the surface of the bridging layer, and performing a second cold pressing to obtain the composite board.

[0026] Preferably, in step 2, the time of the second cold pressing is 12 to 24 hours, preferably 18 to 24 hours, the temperature of the second cold pressing is 18 to 23° C., and the pressure of the second cold pressing is 1.4 to 1.5 MPa.

[0027] Preferably, the method for preparing the core layer plywood comprises: coating the veneers with an inorganic adhesive, assembling the veneers, and performing a first cold pressing to obtain the core layer plywood.

[0028] Preferably, the temperature of the first cold pressing is 18-23° C., the time of the first cold pressing is 12-24 h, preferably 18-24 h, and the pressure of the first cold pressing is 1.2-1.5 MPa, preferably 1.4-1.5 MPa.

[0029] In a third aspect, the present invention provides an application of the composite board material, which is used for at least one of building wall panels, cabinet panels, wardrobe door panels, and interior decoration hanging panels.

[0030] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0031] A) The composite board provided by the present invention uses biomass crushed materials as raw materials, magnesium chloride, magnesium oxide, water, carbon quantum dots, and layered nano-metakaolin as adhesives, wherein the carbon quantum dots introduced in the adhesive can well induce magnesium chloride and magnesium oxide to form a strong anchoring effect with the crushed materials in a humid atmosphere, without the need for surface pretreatment of the crushed materials, and the overall preparation process is simple, which is suitable for large-scale industrial production. In addition, the layered nano-metakaolin has an excellent layered structure. Unlike traditional granular modifiers, the layered nanoparticles help to intersperse between magnesium chloride and magnesium oxide to form a better bridging effect; at the same time, the layered nanomaterials can be better adsorbed on the surface of biomass crushed materials, significantly reducing the water absorption of the composite board, reducing the water absorption thickness expansion rate, and improving the excellent dimensional stability of the board.

[0032] B) The preparation method provided by the present invention adopts cold pressing at room temperature. The surface of the board formed after cold pressing is uniform and flat, and no sanding is required for subsequent decorative veneer, which saves the efficiency of subsequent secondary veneer processing; secondly, the surface layer adopts biomass mixture with high density and good flame retardant performance, which is more resistant to precipitation, not easy to be affected by moisture, and maintains flame retardant performance for a long time than the traditional use of organic flame retardants such as polycarbon quantum dot ammonium.

[0033] C) According to the latest product standard T / CNFPIA 3031-2023 "Fine Plywood Composite Plywood", the surface bonding strength of the board of the present invention meets the specified index requirements (≥0.8MPa), and the 24h absorption thickness expansion rate is only 2.3-4.5%, which is significantly lower than the standard requirements (≤8.0%). The static bending strength of the 18mm board in the length direction can reach 44.8MPa, which is much higher than the standard requirements (20.0MPa) by 2 times. In addition, the composite board of the present invention has excellent flame retardant properties, and the magnesium contained in the surface mixed fragments has a good effect of inhibiting ignition. The plywood substrate is laminated with inorganic adhesive layers, which sets up many flame-retardant "checkpoints" for the material in a fire environment, achieving a long-lasting flame retardant effect. Therefore, the composite board of the present invention can be directly used in indoor home decoration, bathrooms, kitchens and other fields with high requirements for anti-deformation and flame retardant functions.

[0034] D) The board provided by the present invention has multifunctional and long-lasting characteristics such as high surface flatness, good dimensional stability, excellent surface crack resistance, high environmental protection performance, strong flame retardant performance, and high production cost performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 A schematic diagram of the structure of the long-lasting flame-retardant and anti-deformation composite board provided by the present invention;

[0036] Among them, 1-crushed aggregate layer; 2-bridging layer; 3-core plywood. DETAILED DESCRIPTION

[0037] Preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of the present invention and are used to explain the principles of the present invention together with the embodiments of the present invention.

[0038] In the first aspect, the present invention provides a long-lasting flame-retardant and deformation-resistant composite board material, comprising a crushed aggregate layer 1, a bridging layer 2 and a core plywood 3, wherein the crushed aggregate layer 1 is glued to the upper and lower surfaces of the core plywood 3 through the bridging layer 2; the crushed aggregate layer 1 comprises biomass crushed materials and a magnesium adhesive containing carbon quantum dots, and the bridging layer 2 comprises a magnesium adhesive containing carbon quantum dots, wherein the magnesium adhesive containing carbon quantum dots comprises: magnesium chloride, water, carbon quantum dots, magnesium oxide, and layered nano-metakaolin.

[0039] The composite board provided by the present invention has biomass crushed materials and magnesium adhesive containing carbon quantum dots synergistically forming a crushed aggregate layer and the magnesium adhesive containing carbon quantum dots forming a bridging layer, which jointly improve the comprehensive performance of the composite board. The carbon quantum dots introduced in the adhesive can well induce magnesium chloride and magnesium oxide to form a strong anchoring effect with the crushed materials in a humid atmosphere, without the need for surface pretreatment of the crushed materials, and the overall preparation process is simple, which is suitable for large-scale industrial production. In addition, the layered nano-metakaolin has an excellent layered structure. Unlike traditional granular modifiers, the nanoparticles of the layered structure help to intersperse between magnesium chloride and magnesium oxide to form a better bridging effect; at the same time, the layered nanomaterial can be better adsorbed on the surface of the biomass crushed materials, significantly reducing the water absorption of the composite board, reducing the water absorption thickness expansion rate, and improving the excellent dimensional stability of the board.

[0040] In a specific embodiment of the present invention, based on the total weight of the magnesium adhesive containing carbon quantum dots, the content of each component in the magnesium adhesive containing carbon quantum dots is:

[0041] Magnesium chloride 25wt.%-35wt.%, for example 25wt.%, 26wt.%, 27wt.%, 28wt.%, 29wt.%, 30wt.%, 31wt.%, 32wt.%, 33wt.%, 34wt.%, 35wt.%, etc., preferably 28-32wt.%;

[0042] Water 18wt.%-20wt.%; for example 18wt.%, 19wt.%, 20wt.%, etc.;

[0043] Carbon quantum dots 0.5wt.%-2wt.%, such as 0.5wt.%, 0.8wt.%, 1.0wt.%, 1.2wt.%, 1.4wt.%, 1.6wt.%, 1.8wt.%, 2wt.%, etc., preferably 0.8-1.2wt.%;

[0044] 45wt.%-55wt.% of magnesium oxide, for example, 45wt.%, 46wt.%, 47wt.%, 48wt.%, 49wt.%, 50wt.%, 51wt.%, 52wt.%, 53wt.%, 54wt.%, 55wt.%, etc., preferably 48-52wt.%;

[0045] Layered nano-metakaolin 0.5wt.%-3wt.%, for example 0.5wt.%, 0.8wt.%, 1.0wt.%, 1.2wt.%, 1.4wt.%, 1.6wt.%, 1.8wt.%, 2wt.%, 2.2wt.%, 2.4wt.%, 2.6wt.%, 2.8wt.%, 3wt.%, etc., preferably 0.8-1.2wt.%.

[0046] In the present invention, in the magnesium adhesive containing carbon quantum dots, the mass percentages of carbon quantum dots and layered nano-kaolin are respectively in the preferred range of 0.8-1.2wt.%, and the obtained composite board has excellent properties such as surface bonding strength, 24h water absorption thickness expansion rate, static bending strength and flame retardant properties.

[0047] In a specific embodiment of the present invention, in the aggregate layer 1, the mass ratio of the biomass crushed material and the magnesium adhesive containing carbon quantum dots is (0.5-2.0): 1, for example, 0.5: 1, 0.8: 1, 1.2: 1, 1.5: 1, 1.8: 1, 2: 1, etc., preferably (0.8-1.2): 1. It should be noted that when the content of the biomass crushed material in the aggregate layer 1 is higher or lower than the range (0.5-2.0): 1 defined in the present invention, the comprehensive performance of the composite board will be reduced.

[0048] In a specific embodiment of the present invention, the biomass fragments include at least one of straw, wood shavings and reeds.

[0049] In a specific embodiment of the present invention, the particle size of the biomass fragments is 10-32 meshes, such as 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32 meshes, etc., preferably 20-32 meshes, with a moisture content of 10-20%. It should be noted that when the particle size of the fragments is too large (for example, the particle size is less than 10 meshes), the surface texture of the biomass fragment board after molding is rough and uneven, which affects the subsequent veneer gluing; and when the particle size of the fragments is too small (for example, the particle size is greater than 32 meshes), the amount of adhesive applied during molding is increased, resulting in increased costs. When the particle size of the biomass fragments is 10-32 meshes, the surface of the composite board after the biomass fragments are glued, slab molded, and cold pressed is dense and has high flatness.

[0050] In a specific embodiment of the present invention, the particle size of the layered nano-metakaolin is 200-500 nm, the aspect ratio is (4-6):1, and the thickness can be 10-100 nm.

[0051] In a specific embodiment of the present invention, the surface of the carbon quantum dots has surface functional groups, and the surface functional groups include at least one of phosphate groups, amino groups, and sulfate groups.

[0052] In a specific embodiment of the present invention, the carbon quantum dots are preferably prepared by hydrothermal carbonization of biomass fragments, water, and an etching aid. Among them, the etching aid is at least one of ammonium dihydrogen phosphate, diammonium hydrogen phosphate, ammonium polyphosphate, and ammonium sulfate, preferably ammonium sulfate; the hydrothermal carbonization temperature is 160-200°C (preferably 180°C); the hydrothermal carbonization time is 1-3h (preferably carbonization time 1.5h); biomass fragments, water and etching aids are placed in a closed hydrothermal reactor according to a mass ratio of (5-10): 100: (0.5-1.2), and the reaction system is subjected to solid-liquid separation after high-temperature hydrothermal reaction, and the supernatant is carbon quantum dots. The biomass fragments in the carbon quantum dot preparation method can be at least one of straw, wood shavings, and reeds, and their types do not have to be the same as the types of biomass fragments in the aggregate layer 1.

[0053] In the present invention, the carbon quantum dots are biomass fragments and etching aids in an aqueous solution, and the carbon quantum dots with complex amino groups, sulfate groups, etc. are generated by high temperature. The carbon quantum dots are small in size (<10nm), rich in surface functional groups, and have higher environmental protection performance. They can well induce magnesium chloride and magnesium oxide to form a strong anchoring effect with the fragments in a humid atmosphere, and there is no need to pretreat the surface of the fragments, especially biomass fragments such as straw and reeds that are rich in wax and difficult to glue. The overall preparation process is simple and suitable for large-scale industrial production.

[0054] In a specific embodiment of the present invention, the thickness of the crushed aggregate layer 1 is 1.0-2.0 mm. It should be noted that when the thickness of the crushed aggregate layer 1 is too low, less than 1 mm, it is easy to cause uneven paving of the crushed aggregate layer and defects such as holes and insufficient sanding allowance, which affect the subsequent sanding and veneer processing; when the thickness of the crushed aggregate layer 1 is too high, higher than 2 mm, the mechanical strength of the composite board drops sharply and brittle defects begin to become prominent.

[0055] In a specific embodiment of the present invention, the density of the aggregate layer 1 is 0.9-1.0 g / cm 3 .

[0056] In a specific embodiment of the present invention, the density of the magnesium adhesive containing carbon quantum dots is 1.4-1.6 g / cm 3 .

[0057] In a specific embodiment of the present invention, the core plywood 3 is formed by laminating and gluing several layers of veneers with an inorganic adhesive; preferably, the density of the veneers in the core plywood 3 is 0.4-0.5 g / cm 3 , more preferably, the veneer is a eucalyptus veneer.

[0058] In a specific embodiment of the present invention, the thickness of the core plywood 3 is 14-16 mm, and the number of veneer layers is 7-9.

[0059] In a specific embodiment of the present invention, the inorganic adhesive used in the core plywood 3 is at least one of a magnesium adhesive, a silicon adhesive, and a magnesium-silicon mixed adhesive, preferably the magnesium adhesive containing carbon quantum dots.

[0060] The composite board provided by the present invention has a density of the aggregate layer 1 of 0.9 to 1.0 g / cm 3 The density of the veneer in the core plywood 3 is 0.4-0.5 g / cm 3 It is known that the density of traditional organic glue is generally 0.6-0.8 g / cm 3 The density of inorganic adhesive is 1.4~1.6g / cm 3 Therefore, the multilayer structure of "high density-single board-inorganic high density-single board-high density" obtained by the composite board provided by the present invention gives the board higher dimensional stability and is not easy to deform in a humid environment or an electric heating floor environment.

[0061] In a second aspect, the present invention provides a method for preparing a long-lasting flame-retardant and anti-deformation composite sheet, comprising the following steps:

[0062] Step 1: while coating the bridging layer 2 on the upper and lower surfaces of the core plywood 3, preparing a biomass mixture comprising biomass crushed materials and a magnesium adhesive containing carbon quantum dots;

[0063] Step 2: Lay the biomass mixture on the surface of the bridging layer 2, and perform a second cold pressing to obtain a composite board.

[0064] In a specific embodiment of the present invention, in step 2, the time of the second cold pressing is 12 to 24 hours, preferably 18 to 24 hours; the temperature of the second cold pressing is 18 to 23° C.; and the pressure of the second cold pressing is 1.4 to 1.5 MPa.

[0065] In a specific embodiment of the present invention, step 1 comprises:

[0066] Step 1a: preparing the core layer plywood 3: coating the veneer with an inorganic adhesive, assembling the veneer, and performing the first cold pressing. The adhesive does not need to be completely cured to obtain the core layer plywood 3;

[0067] Step 1b: Apply magnesium adhesive containing carbon quantum dots to the upper and lower surfaces of the core plywood 3, preferably, the amount of adhesive applied is 150-220 g / m 2 ;

[0068] Step 1c: uniformly mixing the biomass crushed materials with magnesium chloride, magnesium oxide, water, carbon quantum dots and layered nano-metakaolin to form a biomass mixture.

[0069] In a specific embodiment of the present invention, in step 1a, the amount of glue applied to the single board is 200 to 300 g / m 2 In step 1a, the temperature of the first cold pressing is room temperature (≥10°C), the time of the first cold pressing is 12 to 24 hours, and the pressure of the first cold pressing is 1.2 to 1.5 MPa. More preferably, in step 1a, the temperature of the first cold pressing is 18 to 23°C, the time is 18 to 24 hours, and the pressure is 1.4 to 1.5 MPa.

[0070] In a specific embodiment of the present invention, step 3 is also included: heat treatment and curing, wherein the heat treatment temperature is 60-70°C, preferably 65-70°C; the heat treatment time is 24-48h, preferably 24-36h; the curing temperature is room temperature ≥10°C, preferably 18-23°C; the curing time is 5-7 days. Preferably, the specific steps of step 3 can be: after unloading the pressure, place the pressed composite board in a drying room at 60-70°C for heat treatment for 24-48h, then take it out and cure it at room temperature (≥10°C) for 5-7 days to obtain a long-lasting flame retardant and deformation-resistant composite board.

[0071] The preparation method provided by the present invention is that the plywood substrate is prepared by cold pressing a veneer and an inorganic adhesive at room temperature, and then a biomass mixture is applied to the surface of the plywood (biomass crushed materials are uniformly mixed with a certain proportion of magnesium chloride, magnesium oxide, water, and carbon quantum dots to form a biomass mixture), and cold pressing and curing are performed at room temperature. The surface of the board formed after cold pressing is uniform and flat, and no sanding is required for subsequent decorative veneer, which saves the efficiency of subsequent secondary veneer processing; secondly, the surface layer adopts a large density of mixed crushed materials and has good flame retardant properties, which is more resistant to precipitation, less susceptible to moisture, and has long-term flame retardant properties than the traditional use of organic flame retardants such as polycarbon quantum dot ammonium.

[0072] In a specific embodiment of the present invention, the specific steps of the preparation method of the long-lasting flame retardant and deformation-resistant composite sheet are as follows:

[0073] Step 1a: Use a roller glue device to apply an inorganic adhesive to the veneer, assemble the blanks, and perform the first cold pressing. The inorganic adhesive is one of a magnesium adhesive, a silicon adhesive, and a magnesium-silicon mixed adhesive. The amount of adhesive applied is 200-300 g / m on a single side. 2, the cold pressing time at room temperature is 12 to 24 hours, the cold pressing pressure is 1.2 to 1.5 MPa, and the adhesive does not need to be completely cured to obtain the primary core layer plywood;

[0074] Step 1b: Apply inorganic adhesive to the upper and lower surfaces of the core plywood, with a coating amount of 150-220g / m2 per side. 2 ;

[0075] Step 1c: Evenly mix biomass fragments such as straw, wood shavings, and reeds with a certain proportion of magnesium chloride, magnesium oxide, water, and carbon quantum dots to form a biomass mixture;

[0076] Step 2: Evenly lay the biomass mixture on the upper and lower surfaces of the core inorganic plywood after gluing, and perform the second cold pressing for 12 to 24 hours;

[0077] Step 3: After unloading the pressure, place the pressed composite board in a 60-70°C drying room for heat treatment for 24-48 hours, then take it out and cure it at room temperature (≥10°C) for 5-7 days to obtain a long-lasting flame-retardant and anti-deformation composite board.

[0078] The long-lasting flame-retardant and anti-deformation composite sheet and the preparation method thereof of the present invention have at least the following advantages:

[0079] 1. In the preparation method described in the present invention, the plywood substrate is prepared by cold pressing a single board and an inorganic adhesive at room temperature, and then a biomass mixture is applied to the surface of the plywood (biomass crushed materials are uniformly mixed with a certain proportion of magnesium chloride, magnesium oxide, water, and carbon quantum dots to form a biomass mixture), and cold pressed and cured at room temperature. The surface of the board formed after cold pressing is uniform and flat, and no sanding is required for subsequent decorative veneer, which saves the efficiency of subsequent secondary veneer processing; secondly, the surface layer uses a large density of mixed crushed materials and has good flame retardant properties, which is more resistant to precipitation, less susceptible to moisture, and has long-lasting flame retardant properties than the traditional use of organic flame retardants such as polycarbon quantum dot ammonium; more importantly, the density of the surface crushed materials according to the preparation method of the present invention is 0.9-1.0g / cm 3 The density of traditional veneer is generally 0.4-0.5g / cm 3 It is known that the density of traditional organic glue is generally 0.6-0.8 g / cm 3 The density of inorganic adhesive is 1.4~1.6g / cm 3 Therefore, the multi-layer structure of "high density-single board-inorganic high density-single board-high density" obtained by using inorganic glue gives the board higher dimensional stability and is not easy to deform in humid environments and electric heating floor environments.

[0080] 2. The preparation method of the present invention uses biomass fragments such as straw, wood shavings, and reeds as raw materials, and evenly mixes magnesium chloride, magnesium oxide, water, and carbon quantum dots without pre-treating the fragments. The carbon quantum dots introduced are carbon quantum dots with complex amino and sulfate groups generated by high temperature in aqueous solution of biomass fragments and etching aids, which have small size (<10nm), rich surface functional groups, and higher environmental performance. They can well induce magnesium chloride and magnesium oxide to form a strong anchoring effect with the fragments in a humid atmosphere, and there is no need to pre-treat the surface of the fragments, especially biomass fragments such as straw and reeds that are rich in wax and difficult to glue. The overall preparation process is simple and suitable for large-scale industrial production.

[0081] 3. According to the latest product standard T / CNFPIA3031-2023 "Fine Plywood Composite Plywood", the surface bonding strength of the board of the present invention meets the specified index requirements (≥0.8MPa), and the 24h absorption thickness expansion rate is only 2.3-4.5%, which is significantly lower than the standard requirements (≤8.0%). The static bending strength of the 18mm board in the length direction can reach 44.8MPa, which is much higher than the standard requirements (20.0MPa) by 2 times. In addition, the composite board of the present invention has excellent flame retardant properties. The magnesium contained in the surface mixed fragments plays a good role in inhibiting ignition. The plywood substrate is laminated with inorganic adhesive layers, which sets up many flame-retardant "checkpoints" for the material in a fire environment, achieving a long-lasting flame retardant effect. Therefore, the composite board of the present invention can be directly used in indoor home decoration, bathrooms, kitchens and other fields with high requirements for anti-deformation and flame retardant functions.

[0082] 4. The board material provided by the present invention has multifunctional and long-lasting characteristics such as high surface flatness, good dimensional stability, excellent surface crack resistance, high environmental protection performance, strong flame retardant performance, and high production cost performance.

[0083] In a third aspect, the present invention provides an application of a long-lasting flame-retardant and deformation-resistant composite board material for use in the fields of building wall panels, cabinet panels, wardrobe door panels, interior decoration hanging panels, etc.

[0084] The preferred embodiments of the present invention are described in detail below to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0085] Unless otherwise specified, the reagents used in the present invention are commercially available products.

[0086] The particle size of the layered nano-metakaolin is 200-500 nm, the aspect ratio is (4-6):1, and the thickness is 10-100 nm.

[0087] Example 1

[0088] The preparation method of the carbon quantum dots used in this embodiment is as follows: straw, water, and ammonium sulfate etching aid are prepared by high-temperature hydrothermal carbonization at 180°C for 1.5 hours, and are placed in a closed hydrothermal reactor at a mass ratio of 5:100:0.5. After the high-temperature hydrothermal reaction, the reaction system is separated into solid and liquid, and the supernatant is the carbon quantum dots.

[0089] The preparation method of the magnesium adhesive containing carbon quantum dots used in this embodiment is as follows: 0.75 kg of magnesium chloride and 0.45 kg of water are mixed, 0.025 kg of carbon quantum dots are added, and after stirring, 1.25 kg of magnesium oxide and 0.025 kg of layered nano-metakaolin are added.

[0090] The preparation method of the composite board is as follows:

[0091] Step 1a: Preparation of inorganic plywood substrate: The veneer is coated with the magnesium inorganic adhesive prepared in this embodiment by roller, with a single-side coating amount of 300 g / m 2 , cold pressing at room temperature for 24 hours, cold pressing pressure 1.5MPa, forming a core plywood 3 with a thickness of 16mm,

[0092] Step 1b: The core plywood 3 is then coated with the magnesium inorganic adhesive prepared in this embodiment on both the upper and lower sides by rollers, with the coating amount on one side being 300 g / m 2 .

[0093] Step 1c: Mixing the crushed materials: 2.5 kg of 32-mesh straw crushed materials are added with 0.75 kg of magnesium chloride, 0.45 kg of water, 0.025 kg of carbon quantum dots, 1.25 kg of magnesium oxide and 0.025 kg of layered nano-metakaolin in sequence, and the mixture is thoroughly mixed to form a biomass mixture.

[0094] Step 2: Preparation of composite board: pre-pave 1mm thick biomass mixture, place the glued core plywood 3 on the surface of the biomass mixture through a suction cup, and then pave 1mm thick biomass mixture, cold press for 12h at room temperature 23℃, cold press pressure 1.5MPa,

[0095] Step 3: After forming, place the composite board in a 70°C drying room for 24 hours, and then place it at 23°C room temperature for 5 days until the moisture content of the board is about 12%.

[0096] Example 2

[0097] The preparation method of the carbon quantum dots used in this embodiment is as follows: straw, water, and ammonium sulfate etching aid are prepared by high-temperature hydrothermal carbonization at 180°C for 1.5 hours, and are placed in a closed hydrothermal reactor at a mass ratio of 5:100:0.5. After the high-temperature hydrothermal reaction, the reaction system is separated into solid and liquid, and the supernatant is the carbon quantum dots.

[0098] The preparation method of the magnesium adhesive containing carbon quantum dots used in this embodiment is as follows: 0.75 kg of magnesium chloride and 0.45 kg of water are mixed, 0.025 kg of carbon quantum dots are added, and after stirring, 1.25 kg of magnesium oxide and 0.025 kg of layered nano-metakaolin are added.

[0099] The preparation method of the composite board is as follows:

[0100] Step 1a: Preparation of inorganic plywood substrate: The veneer is coated with the magnesium inorganic adhesive prepared in this embodiment by roller, with a single-side coating amount of 300 g / m 2 , cold pressing at room temperature for 24 hours, cold pressing pressure 1.5MPa, forming a core plywood 3 with a thickness of 16mm,

[0101] Step 1b: The core plywood 3 is then coated with the magnesium inorganic adhesive prepared in this embodiment on both the upper and lower sides by rollers, with the coating amount on one side being 300 g / m 2 .

[0102] Step 1c: Mixing the crushed materials: 2.5 kg of 10-mesh wood shavings were added with 0.75 kg of magnesium chloride, 0.45 kg of water, 0.025 kg of carbon quantum dots, 1.25 kg of magnesium oxide and 0.025 kg of layered nano-metakaolin in sequence, and mixed thoroughly to form a biomass mixture.

[0103] Step 2: Preparation of composite board: pre-pave 1mm thick biomass mixture, place the glued core plywood 3 on the surface of the biomass mixture through a suction cup, and then pave 1mm thick biomass mixture, cold press for 12h at room temperature 23℃, cold press pressure 1.5MPa,

[0104] Step 3: After forming, place the composite board in a 70°C drying room for 24 hours, and then place it at 23°C room temperature for 5 days until the moisture content of the board is about 12%.

[0105] Example 3

[0106] The preparation method of carbon quantum dots is as follows: straw, water, and ammonium sulfate etching aid are prepared by high-temperature hydrothermal carbonization at 180°C for 1.5 hours, and are placed in a closed hydrothermal reactor at a mass ratio of 5:100:0.5. After the high-temperature hydrothermal reaction, the reaction system is separated into solid and liquid, and the supernatant is the carbon quantum dots.

[0107] The preparation method of the magnesium adhesive containing carbon quantum dots used in this embodiment is as follows: 0.75 kg of magnesium chloride and 0.45 kg of water are mixed, 0.025 kg of carbon quantum dots are added, and after stirring, 1.25 kg of magnesium oxide and 0.025 kg of layered nano-metakaolin are added.

[0108] The preparation method of the composite board is as follows:

[0109] Step 1a: Preparation of inorganic plywood substrate: The veneer is coated with the magnesium inorganic adhesive prepared in this embodiment by roller, with a single-side coating amount of 300 g / m 2 , cold pressing at room temperature for 24 hours, cold pressing pressure 1.5MPa, forming a core plywood 3 with a thickness of 14mm,

[0110] Step 1b: The core plywood 3 is then coated with the magnesium inorganic adhesive prepared in this embodiment on both the upper and lower sides by rollers, with the coating amount on one side being 300 g / m 2 .

[0111] Step 1c: Mixing the crushed materials: 2.5 kg of 32-mesh straw crushed materials are added with 0.75 kg of magnesium chloride, 0.45 kg of water, 0.025 kg of carbon quantum dots, 1.25 kg of magnesium oxide and 0.025 kg of layered nano-metakaolin in sequence, and the mixture is thoroughly mixed to form a biomass mixture.

[0112] Step 2: Preparation of composite board: pre-pave 1mm thick biomass mixture, place the glued core plywood 3 on the surface of the scraps through the suction cup, and then pave 1mm thick mixed scraps, cold press for 12h at room temperature 23℃, cold pressing pressure 1.5MPa,

[0113] Step 3: After forming, place the composite board in a 70°C drying room for 24 hours, and then place it at 23°C room temperature for 5 days until the moisture content of the board is about 12%.

[0114] Example 4

[0115] This embodiment is basically the same as Embodiment 3, except that the thickness of the biomass mixture laid in Step 2 is 2 mm.

[0116] Example 5

[0117] This embodiment is basically the same as Example 1, except that, during the preparation of the magnesium adhesive containing carbon quantum dots and during the formation of the biomass mixture in step 1c, the amounts of the adhesive components are: 0.75 kg of magnesium chloride, 0.45 kg of water, 0.035 kg of carbon quantum dots, 1.25 kg of magnesium oxide, and 0.015 kg of layered nano-kaolin.

[0118] Example 6

[0119] This embodiment is basically the same as Example 1, except that, in the preparation process of the magnesium adhesive containing carbon quantum dots and in the process of forming the biomass mixture in step 1c, the amounts of the adhesive components are: 0.75 kg of magnesium chloride, 0.45 kg of water, 0.015 kg of carbon quantum dots, 1.25 kg of magnesium oxide, and 0.035 kg of layered nano-kaolin.

[0120] Example 7

[0121] This embodiment is basically the same as the embodiment 1, except that in the aggregate layer, the amount of 32-mesh straw aggregate used is 3.75 kg.

[0122] Example 8

[0123] This embodiment is basically the same as the embodiment 1, except that in the crushed aggregate layer, the particle size of the straw is 20 meshes.

[0124] Comparative Example 1

[0125] A common organic polyurethane adhesive (Wanhua Company, solid content 100%) was selected for comparison.

[0126] The preparation method of the composite board is as follows:

[0127] Step 1a: Preparation of organic plywood substrate: The veneer is roller coated with polyurethane adhesive, with a single-sided coating of 300g / m 2 , cold pressing at room temperature for 24 hours, cold pressing pressure 1.5MPa, forming a core plywood 3 with a thickness of 16mm,

[0128] Step 1b: Then, the core plywood 3 is coated with organic adhesive on both the upper and lower sides by rollers, with the amount of adhesive applied on one side being 300 g / m 2 .

[0129] Step 1c: Mixing the crushed materials: 2.5 kg of 32-mesh straw crushed materials are added with 0.75 kg of magnesium chloride, 0.45 kg of water, 0.025 kg of carbon quantum dots (prepared by the same method as in Example 1), 1.25 kg of magnesium oxide and 0.025 kg of layered nano-metakaolin in sequence, and mixed thoroughly to form a biomass mixture.

[0130] Step 2: Preparation of composite board: pre-pave 1mm thick mixed scraps, place the glued core plywood 3 on the scrap surface through the suction cup, and then pave 1mm thick mixed scraps, cold press for 12h at room temperature 23℃, cold pressing pressure 1.5MPa,

[0131] Step 3: After forming, place the composite board in a 70°C drying room for 24 hours, and then place it at 23°C room temperature for 5 days until the moisture content of the board is about 12%.

[0132] Comparative Example 2

[0133] The preparation method of carbon quantum dots is the same as that in Example 1.

[0134] Preparation of magnesium adhesive: 0.75 kg of magnesium chloride was mixed with 0.45 kg of water, and then 0.025 kg of carbon quantum dots were added. After stirring, 1.25 kg of magnesium oxide and 0.025 kg of layered nano-metakaolin were added.

[0135] The preparation method of the composite board is as follows:

[0136] Step 1a: Preparation of inorganic plywood substrate: The veneer is roller coated with magnesium inorganic adhesive, with a single-sided adhesive coating of 300g / m 2 , cold pressing at room temperature for 24 hours, cold pressing pressure 1.5MPa, forming a core plywood 3 with a thickness of 16mm,

[0137] Step 1b: Then, the core plywood 3 is coated with inorganic adhesive on both the upper and lower sides, with the amount of adhesive applied on one side being 300 g / m 2 .

[0138] Step 1c: Mixing of crushed materials: 2.5 kg of 32-mesh straw crushed materials and 0.25 kg of polyurethane adhesive (satisfying the distribution of adhesive in straw crushed materials), fully mixed. Common organic polyurethane adhesive (Wanhua Company, solid content 100%) was selected for comparison, and the surface crushed materials were mixed to form a biomass mixture.

[0139] Step 2: Preparation of composite board: pre-pave 1mm thick mixed biomass mixture, place the glued core plywood 3 on the surface of the scraps through the suction cup, and then pave 1mm thick mixed scraps, cold press for 12h at room temperature 23℃, cold pressing pressure 1.5MPa,

[0140] Step 3: After forming, place the composite board in a 70°C drying room for 24 hours, and then place it at 23°C room temperature for 5 days until the moisture content of the board is about 12%.

[0141] Comparative Example 3

[0142] This comparative example is basically the same as Example 1, except that the crushed aggregate layer 1 is replaced by an immersion flame-retardant plywood (organic adhesive) layer commonly used in the prior art.

[0143] Comparative Example 4

[0144] This comparative example is basically the same as Example 1, except that during the preparation of the magnesium adhesive containing carbon quantum dots and during the formation of the biomass mixture in step 1c, the carbon quantum dots in the magnesium adhesive are replaced with graphite powder (particle size is 10 nm).

[0145] Comparative Example 5

[0146] This comparative example is basically the same as Example 1, except that, during the preparation of the magnesium adhesive containing carbon quantum dots and during the formation of the biomass mixture in step 1c, the layered nano-metakaolin is replaced with granular nano-metakaolin (particle size is 200-500 nm).

[0147] Test Case

[0148] The physical and chemical properties of the composite board were tested with reference to T / CNFPIA 3031-2023 "fine wood composite plywood" and the flame retardant performance was tested with reference to GB 8624-2012 "combustion performance classification of building materials and products". The test results of the embodiments and comparative examples are listed in Table 1.

[0149] Table 1 Performance parameters of the embodiments and comparative examples

[0150]

[0151] In Comparative Example 1, a common organic polyurethane adhesive was used to prepare the plywood substrate. The composite board formed with the scraps had a high 24h absorption thickness expansion rate and a low static bending strength. This was mainly because the traditional organic adhesive did not form a good bond under the cold pressing process, resulting in a lack of a tight bond between the scraps and the plywood substrate. In addition, the oxygen index of the composite board was low and did not meet the flame retardant (B1) grade requirement for an oxygen index ≥30% for flat panel materials.

[0152] In Comparative Example 2, when the traditional organic polyurethane adhesive is used for mixing the surface chips, the surface bonding strength of the composite board is very low when the preparation method of the present invention is adopted, which is mainly because the surface chips do not form a good bonding under the cold pressing condition, and the 24h absorption thickness expansion rate does not meet the standard, which is mainly because the traditional polyurethane adhesive needs to be cured under the action of heat, and the surface chips under the cold pressing condition do not form a good bonding, resulting in poor dimensional stability and low static bending strength of the product when exposed to water; in addition, since the organic adhesive and the chips used in the surface are both flammable and combustible materials, the oxygen index of the composite board is low, and the surface is easily burned when ignited, resulting in the defect of low flame retardant performance.

[0153] In Comparative Example 3, the immersion flame-retardant plywood (organic adhesive) layer commonly used in the prior art is used to replace the crushed aggregate layer 1 of the present invention. The surface bonding strength is significantly reduced, and the 24h absorption thickness expansion rate is increased, and the static bending strength is reduced. It is a flammable and combustible material, and the comprehensive performance is significantly deteriorated.

[0154] In Comparative Example 4, the carbon quantum dots in the adhesive in the composite board were replaced with graphite powder, the surface bonding strength was significantly reduced, the 24h water absorption thickness expansion rate was significantly increased, the static bending strength and oxygen content were significantly reduced, and the overall performance was significantly deteriorated.

[0155] In Comparative Example 5, the layered nano-kaolin in the adhesive in the composite board is replaced by non-layered granular nano-kaolin, the surface bonding strength is significantly reduced, the 24h water absorption thickness expansion rate is significantly increased, the static bending strength and oxygen content are significantly reduced, and the comprehensive performance is significantly deteriorated.

[0156] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation to the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein, on the contrary, the present invention can be extended to all other methods and applications with the same functions.

Claims

1. A long-lasting flame-retardant and anti-deformation composite sheet, characterized in that: The invention comprises a crushed aggregate layer (1), a bridging layer (2) and a core plywood (3), wherein the crushed aggregate layer (1) is glued to the upper surface and the lower surface of the core plywood (3) through the bridging layer (2); the crushed aggregate layer (1) comprises biomass crushed materials and a magnesium adhesive containing carbon quantum dots; the bridging layer (2) comprises a magnesium adhesive containing carbon quantum dots, wherein: Based on the total weight of the magnesium adhesive containing carbon quantum dots, the magnesium adhesive containing carbon quantum dots includes: 25wt.%-35wt.% magnesium chloride, 18wt.%-20wt.% water, 0.5wt.%-2wt.% carbon quantum dots, 45wt.%-55wt.% magnesium oxide, and 0.5wt.%-3wt.% layered nano-metakaolin.

2. The composite sheet material according to claim 1, characterized in that: In the aggregate layer (1), the mass ratio of the biomass aggregate to the magnesium adhesive containing carbon quantum dots is (0.5-2.0):1; And / or, the biomass debris includes at least one of straw, wood shavings, and reeds; And / or, the particle size of the biomass fragments is 10-32 meshes.

3. The composite sheet material according to claim 1, characterized in that: In the magnesium adhesive containing carbon quantum dots, the surface of the carbon quantum dots has surface functional groups, and the surface functional groups include at least one of a phosphate group, an amino group, and a sulfate group; And / or, the particle size of the layered nano-metakaolin is 200-500 nm, and the aspect ratio is (4-6):

1.

4. The composite sheet material according to any one of claims 1 to 3, characterized in that: The thickness of the crushed aggregate layer (1) is 1-2 mm; And / or, the thickness of the core plywood (3) is 14-16 mm; And / or, the core plywood (3) is formed by laminating and gluing a plurality of veneers with an inorganic adhesive; Preferably, the veneer is a eucalyptus veneer; Preferably, the number of veneer layers in the core plywood (3) is 7-9.

5. The composite sheet material according to claim 4, characterized in that: The inorganic adhesive includes at least one of a magnesium adhesive, a silicon adhesive, and a magnesium-silicon mixed adhesive; Preferably, the inorganic adhesive is the magnesium adhesive containing carbon quantum dots.

6. A method for preparing the composite sheet material according to any one of claims 1 to 5, characterized in that: The steps include: Step 1: coating a bridging layer (2) on the upper and lower surfaces of a core plywood (3); Step 2: laying a biomass mixture comprising biomass crushed materials and a magnesium adhesive containing carbon quantum dots on the surface of the bridging layer (2), and performing a second cold pressing to obtain the composite board.

7. The preparation method according to claim 6, characterized in that: In step 2, the second cold pressing time is 12 to 24 hours, preferably 18 to 24 hours. and / or, the temperature of the second cold pressing is 18-23°C, And / or, the pressure of the second cold pressing is 1.4 to 1.5 MPa.

8. The preparation method according to claim 6 or 7, characterized in that: The preparation method of the core layer plywood (3) comprises: The veneer is coated with an inorganic adhesive, assembled, and subjected to a first cold pressing to obtain the core layer plywood (3).

9. The preparation method according to claim 8, characterized in that: The temperature of the first cold pressing is 18-23°C. and / or, the first cold pressing time is 12 to 24 hours, preferably 18 to 24 hours, And / or, the first cold pressing pressure is 1.2 to 1.5 MPa, preferably 1.4 to 1.5 MPa.

10. An application of the composite board according to any one of claims 1 to 5, characterized in that: Used for at least one of building wall panels, cabinet panels, wardrobe door panels, and interior decoration panels.

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