Multi-scale recombined wood composite board and manufacturing method thereof

Abstract

The invention provides a multi-scale recombined wood composite board and a manufacturing method thereof. The composite material comprises wood shavings, a functional auxiliary agent and an adhesive, and the functional auxiliary agent comprises a biomass-based waterproof agent and / or a metal oxide. The composite material provided by the embodiment of the invention contains the functional auxiliary agent, has an excellent waterproof effect, can effectively prevent the composite material from being damped and deformed in a humid environment, improves the dimensional stability of the composite material, and realizes multi-purpose and multi-scene application; the functional auxiliary agent comprises a biomass-based waterproof agent and / or a metal nano oxide, the raw material of the biomass-based waterproof agent is mainly derived from a biomass material, the paper pulp by-product lignin-based compound can be efficiently utilized, the paraffin-based material in the composite material can be reduced, and finally the carbon emission is reduced; the metal nano oxide has water resistance and also has certain flame retardance, so that the application functionality of the composite material is further improved.

Description

Technical Field

[0001] The present application relates to the technical field of building materials, and in particular to a multi-scale reorganized wood composite board and a manufacturing method thereof. Background Art

[0002] In recent years, the growing demand for sustainable and high-performance materials has driven significant progress in the field of wood-based composites. Wood-based composites have been widely used in various usage scenarios due to their renewable, biodegradable and recyclable advantages. Considering the functional properties, an important application feature of wood-based composites is dimensional stability, especially in humid environments. The porosity and chemical composition of the wood matrix determine the hydrophilicity of wood, which will lead to the deterioration of its physical and mechanical properties due to changes in environmental moisture content and have an adverse effect on the overall structural stability. The wood matrix is ​​usually combined with adhesives or reinforcements to enhance durability, strength and resistance to moisture-related problems. Adhesive bonding or reinforcements play a vital role in preventing moisture penetration, minimizing the impact of moisture on the composite by creating a barrier between the wood. However, due to the limitations of related technologies, traditional wood composites are susceptible to moisture deformation in humid environments, affecting the service life of the material and the stability of its physical and mechanical properties. Therefore, the current wood-based composites still need to be further improved. Summary of the invention

[0003] In view of this, the embodiments of the present application provide a composite material and a composite board and a method for preparing the same.

[0004] In a first aspect, the present application provides a composite material, comprising:

[0005] Wood chips, functional additives and adhesives;

[0006] Among them, the functionalized additives include biomass-based waterproofing agents and / or metal nano-oxides.

[0007] In one embodiment, the biomass-based waterproofing agent comprises a paraffin-based material and a lignin-based compound, wherein the lignin-based compound covers at least a portion of the paraffin-based material;

[0008] Preferably, the lignin-based compound encapsulates the paraffin-based material to form a core-shell structure;

[0009] Preferably, the paraffin-based material includes at least one of solid paraffin, molten paraffin and paraffin emulsion;

[0010] Preferably, the lignin-based compound comprises a pulp and papermaking byproduct;

[0011] Preferably, the lignin-based compound comprises at least one of lignin sulfonate, sulfite lignin and sulfate lignin;

[0012] Preferably, the solid content of the biomass-based waterproofing agent is 20-80%.

[0013] In one embodiment, the metal nano-oxide includes at least one of nano-iron oxide, nano-aluminum oxide, nano-copper oxide, and nano-titanium oxide;

[0014] Preferably, the particle size of the metal nano-oxide is 20-50 nm.

[0015] In one embodiment, the moisture content of the wood chips is 2-20%;

[0016] Preferably, the wood shavings have a thickness of 0.4-1.6 mm, a length of 3-25 cm, and a width of 3-10 cm;

[0017] Preferably, the adhesive comprises at least one of a biomass adhesive, a urea-formaldehyde resin and an isocyanate.

[0018] In one embodiment, the mass of the biomass-based waterproofing agent is 1-12% of the dry weight of the wood chips;

[0020] and / or, the mass of the metal nano-oxide is 0.1-5.0% of the dry weight of the wood chips;

[0021] And / or, the mass of the adhesive is 1-25% of the dry weight of the wood chips.

[0022] A second aspect of the present application provides a composite board material, comprising: a core layer, the core layer comprising the aforementioned composite material;

[0023] A first surface layer is located on at least a portion of the surface of the core layer, and the first surface layer includes the aforementioned composite material; and crosslinking exists at the interface where the core layer and the first surface layer are connected;

[0024] The functionalized auxiliary agent in the core layer includes one of a biomass-based waterproofing agent and a metal oxide, and the functionalized auxiliary agent in the first surface layer includes the other of a biomass-based waterproofing agent and a metal oxide.

[0025] In one embodiment, the mass of the first surface layer accounts for 10-60% of the mass of the composite board, and the mass of the core layer accounts for 40-90% of the mass of the composite board;

[0026] Preferably, the biomass-based waterproofing agent is paved by physical layering, and / or the metal nano-oxide is paved by physical layering.

[0027] In one embodiment, it further comprises a second surface layer, which is located on the side of the first surface layer away from the core layer, and the second surface layer comprises the aforementioned composite material;

[0028] Preferably, the mass of the first surface layer accounts for 10-40% of the mass of the composite board, the mass of the second surface layer accounts for 10-50% of the mass of the composite board, and the mass of the core layer accounts for 30-80% of the mass of the composite board.

[0029] The third aspect of the present application provides a method for preparing the aforementioned composite board, comprising:

[0030] Mixing wood chips, a biomass-based waterproofing agent, and an adhesive to obtain a first mixture;

[0031] mixing wood shavings, metal nano-oxides and adhesive to obtain a second mixture;

[0032] The first mixture and the second mixture are alternately and layered in sequence to obtain a multi-layer board material layer;

[0033] The raw material layers of the multi-layer board are subjected to hot pressing treatment to obtain a composite board.

[0034] In one embodiment, the temperature of the hot pressing treatment is 120-210°C;

[0035] Preferably, the paving method of the first mixture comprises:

[0036] The paraffin-based material and the lignin-based compound are mixed at 40-100° C. to obtain a biomass-based waterproofing agent;

[0037] A biomass-based water repellent is added to the wood chips.

[0038] The composite material provided according to the embodiment of the present application contains a waterproof functional additive, which has excellent waterproof effect, forms an efficient waterproof barrier and can effectively prevent the composite material from absorbing moisture in a humid environment. At the same time, the lignin-based compounds in the biomass-based waterproofing agent can reconstruct the molecular network with the adhesive, effectively improve the bonding performance between heterogeneous structural units, and can be efficiently reorganized on a unit scale; the functional additives include biomass-based waterproofing agents and / or metal nano-oxides, both of which have good waterproof effects and are environmentally friendly; the metal nano-oxides have a certain flame retardancy while being waterproof, further improving the performance of the composite material. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a schematic diagram of the molecular structure of a biomass-based waterproofing agent in one embodiment of the present application.

[0040] Figure 2 This is a scanning electron microscope schematic diagram of a biomass-based waterproofing agent in one embodiment of the present application.

[0041] Figure 3 This is a schematic diagram of the reorganization of wood chips, biomass-based waterproofing agent, and adhesive in one embodiment of the present application.

[0042] Figure 4 This is a schematic diagram of a reaction equation for the polymerization reaction of lignin sulfonate and adhesive to generate lignin polyurethane in one embodiment of the present application.

[0043] Figure 5 This is a schematic diagram of the structure of a composite board in one embodiment of the present application.

[0044] Figure 6 This is a schematic diagram of the structure of a composite board in another embodiment of the present application.

[0045] Figure 7 This is a schematic diagram of a process for preparing a composite board in one embodiment of the present application. DETAILED DESCRIPTION

[0046] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0047] In addition, in order to better illustrate the present application, numerous specific details are given in the following specific embodiments. It should be understood by those skilled in the art that the present application can also be implemented without certain specific details. In some examples, methods and means well known to those skilled in the art are not described in detail in order to highlight the subject matter of the present application.

[0048] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0049] In addition, the terms “first”, “second”, etc., if used, are merely used to distinguish between the descriptions and should not be understood as indicating or implying relative importance.

[0050] The inventors of the present application have found that the combination of the reinforcing phase in the composite material cannot completely prevent the environment from absorbing water, so adding a functionalized additive to form a multi-scale waterproof barrier can effectively achieve the purpose of improving dimensional stability and enhancing moisture resistance. Commonly used waterproof functionalized additives are mainly different types of synthetic paraffin waxes, all of which have good moisture resistance and moisture resistance. Since paraffin is a hydrophobic compound, it is widely used to cover the surface or interior of the material based on the mechanism of the lotus effect. Although paraffin coatings are still widely used, most of them have been replaced by paraffin emulsions with superior performance, which use stearic acid or oleic acid and ammonia to emulsify paraffin at a lower cost. However, the application of ordinary waterproofing agents has certain limitations, including large usage leading to reduced adhesion and decreased mechanical properties, and mainly petroleum-based materials, which are not conducive to the recycling of materials. Therefore, it is necessary to explore more sustainable methods to effectively improve waterproofing performance. Lignin sulfonates are not only harmless to humans and animals, but also easily degraded, and are called green chemical products. At present, they have attracted much attention due to their eco-friendliness, renewable sources and sustainability, which are derived from renewable resources such as plants or bio-products. Their production and use help reduce the overall carbon footprint. Compared with traditional petroleum-based products, biomass-based material alternatives have a much smaller impact on the environment by reducing greenhouse gas emissions, minimizing waste, and supporting the transition to a more sustainable future. Therefore, a synchronous restructuring strategy from a multi-scale structure is proposed to effectively improve the dimensional stability of wood composites without affecting the mechanical properties of the materials, which can be suitable for applications in multiple scenarios such as building structures.

[0051] In view of this, the first aspect of the present application provides a composite material, comprising: wood chips, a functional additive and an adhesive, wherein the functional additive comprises a biomass-based waterproofing agent and / or a metal nano-oxide.

[0052] The composite material provided according to the embodiment of the present application contains a waterproof functional additive, which has excellent waterproof effect, forms an efficient waterproof barrier and can effectively prevent the composite material from absorbing moisture in a humid environment. At the same time, the lignin-based compounds in the biomass-based waterproofing agent can cross-link with each other to reconstruct the molecular network, and react with the adhesive (such as isocyanate adhesive) to obtain a polyurethane polymer material, which effectively improves the bonding performance between heterogeneous structural units and can be efficiently reorganized at the molecular scale and the unit scale respectively; the functional additives include biomass-based waterproofing agents and / or metal nano-oxides, both of which have good waterproof effects and are environmentally friendly; the metal nano-oxide has a certain flame retardancy while having waterproof properties, further improving the performance of the composite material.

[0053] Illustratively, the biomass-based waterproofing agent contains moisture, and in the process of using the composite material to prepare the composite board, the heat transfer efficiency is high and the production efficiency is high.

[0054] In one embodiment, the biomass-based waterproofing agent includes a paraffin-based material and a lignin-based compound, and the lignin-based compound covers at least a portion of the main waterproofing material. It is understood that the lignin-based compound covers at least a portion of the paraffin-based material to form a stable core-shell structure, so that the paraffin-based material forms nano-scale particles that can be evenly dispersed in an aqueous solution, and the paraffin-based material can be prevented from agglomerating, so that the biomass-based waterproofing agent can be stored for a longer time.

[0055] For example, the schematic diagram of the structure of the biomass-based waterproofing agent is shown in Figure 1 , biomass-based waterproofing agents are obtained by molecular-scale reorganization. For example, Figure 1 In the figure, 10 represents paraffin, 20 represents lignin, 30 represents negative charge, and 40 represents positive charge.

[0056] For example, refer to Figure 2 The lignin-based compound covers at least a portion of the paraffin-based material to form a stable core-shell structure.

[0057] It can be understood that in the process of using composite materials to prepare composite boards, the lignin-based compounds in the biomass-based waterproofing agent can cross-link with themselves to form a molecular network structure when heated, effectively improving the bonding performance of the board; on the other hand, the paraffin-based material still maintains a nano-sized spherical structure after heating, evenly covering the surface of the wood particle unit, effectively preventing moisture from entering the interior of the board, thereby making the composite board have an excellent waterproof effect.

[0058] For example, refer to Figure 3 In the process of using composite materials to prepare composite boards, the reorganization between heterogeneous structural units not only occurs through physical methods such as spraying, but also through chemical component reconstruction. The lignin-based compounds in the biomass-based waterproofing agent undergo chemical component reconstruction during the hot pressing process, mainly through the polymerization reaction of lignin sulfonate and adhesive to form lignin polyurethane. The reconstruction of the above chemical components helps to improve the bonding performance of the board. For example, the reaction equation for the polymerization reaction of lignin sulfonate and adhesive isocyanate to form lignin-based polyurethane monomer can be referred to Figure 4 .

[0059] In one embodiment, the paraffin-based material includes at least one of solid paraffin, molten paraffin and paraffin emulsion. Therefore, the paraffin-based material has excellent waterproof effect.

[0060] In one embodiment, the lignin-based compound includes a byproduct of pulp and papermaking, and optionally, the lignin-based compound includes at least one of lignin sulfonate, sulfite lignin, and sulfate lignin. Thus, the lignin-based compound has hydrophilic and hydrophobic groups, so that the paraffin-based material is dispersed more evenly and is not easy to condense, effectively reducing the particle size of the biomass-based waterproofing agent; when the lignin-based compound is heated, it can cross-link with itself to form a molecular network structure with a gluing effect, and at the same time, the phenolic hydroxyl group in the lignin skeleton can undergo a polymerization reaction with isocyanate to form a polyurethane-like polymer material, which effectively improves the gluing performance of the board, thereby solving the problem of the gluing performance of the material when the traditional paraffin-based material is used as a waterproofing agent.

[0061] In one embodiment, the solid content of the biomass-based waterproofing agent is 20-80%, for example, 20%, 30%, 40%, 50%, 60%, 70% or 80%, etc. Therefore, the content of the paraffin-based material in the biomass-based waterproofing agent is appropriate, so that the composite material has a better waterproof effect.

[0062] In one embodiment, the metal nano-oxide includes at least one of nano-iron oxide, nano-aluminum oxide, nano-copper oxide and nano-titanium oxide. The metal nano-oxide has excellent hydrophobic effect and can also improve the fire resistance of the composite material; the metal nano-oxide also has certain antibacterial properties; and can improve the efficient functional application of the board.

[0063] In one embodiment, the particle size of the metal nano-oxide is 20-50 nm, for example, 20 nm, 30 nm, 40 nm or 50 nm, etc. Therefore, the metal nano-oxide has a suitable particle size, a large specific surface area, and an excellent hydrophobic effect; and is conducive to being evenly distributed in the composite material, so that the surface flatness of the composite plate prepared using the composite material is higher.

[0064] In one embodiment, the moisture content of the wood chips is 2-20%, for example, 2%, 4%, 6%, 8%, 10%, 12%, 14%, 16%, 18% or 20%, etc. Therefore, the moisture content of the wood chips is appropriate, so that the composite board is effectively reorganized at the molecular, unit and interface scales, and the curing ability and heat transfer efficiency of the adhesive are improved, thereby improving the stability and mechanical properties of the composite board, with strong deformation resistance, high strength and long service life.

[0065] In one embodiment, the thickness of the wood shavings is 0.4-1.6 mm (for example, 0.4 mm, 0.6 mm, 0.8 mm, 1 mm, 1.2 mm, 1.4 mm or 1.6 mm, etc.), the length is 3-25 cm (for example, 3 cm, 5 cm, 8 cm, 10 cm, 12 cm, 14 cm, 16 cm, 18 cm, 20 cm, 22 cm or 25 cm, etc.), and the width is 3-10 cm (for example, 3 cm, 4 cm, 5 cm, 6 cm, 7 cm, 8 cm or 10 cm, etc.). Thus, the size of the wood shavings is appropriate, so that the static bending strength of the composite board is high; the water absorption rate of the wood shavings is low, which improves the moisture resistance and dimensional stability of the composite board; the planar density deviation of the composite board is small and the overall density uniformity is high.

[0066] Exemplarily, the main specifications of the wood chips are long flat chips and wide flat chips.

[0067] Preferably, the adhesive comprises at least one of a biomass adhesive, a urea-formaldehyde resin and an isocyanate.

[0068] In one embodiment, the mass of the biomass-based waterproofing agent is 1-12% of the dry weight of the wood shavings (for example, it can be 1%, 2%, 4%, 6%, 8%, 10% or 12%, etc.), the mass of the metal nano-oxide is 0.1-5.0% of the dry weight of the wood shavings (for example, it can be 0.1%, 0.2%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.5%, 3%, 4% or 5%, etc.), and the mass of the adhesive is 1-25% of the dry weight of the wood shavings (for example, it can be 1%, 2%, 4%, 6%, 8%, 10%, 12%, 15%, 18%, 20%, 22% or 25%, etc.). Thus, the content of each component in the composite material is appropriate, which is conducive to improving the moisture resistance and dimensional stability of the composite board.

[0069] Exemplarily, when the adhesive is a biomass adhesive, the mass of the adhesive is 2-10% of the dry weight of the wood chips; when the adhesive is an isocyanate, the mass of the adhesive is 1-6%; when the adhesive is a urea-formaldehyde resin, the mass of the adhesive is 5-20% of the dry weight of the wood chips.

[0070] It can be understood that composite materials include two scales of reorganization, namely molecular scale reorganization and unit scale reorganization. Molecular scale reorganization refers to the construction of the core-shell structure of the biomass-based waterproofing agent, and unit scale reorganization refers to the unit reconstruction of the heterogeneous structural units of wood chips, functional additives and adhesives according to different proportions.

[0071] The second aspect of the present application provides a composite board, referring to Figure 5The structural schematic diagram of the composite board material shown in the figure, the composite board material comprises: a core layer 100, the core layer 100 comprises the aforementioned composite material; a first surface layer 200, located on at least a portion of the surface of the core layer 100, the first surface layer 200 comprises the aforementioned composite material; wherein the waterproofing agent in the core layer 100 comprises one of a biomass-based waterproofing agent and a metal nano-oxide, and the waterproofing agent in the first surface layer 200 comprises the other of a biomass-based waterproofing agent and a metal nano-oxide; crosslinking exists at the interface where the core layer 100 and the first surface layer 200 are connected.

[0072] It should be noted that the cross-linking at the interface between the core layer 100 and the first surface layer 200 is due to the reorganization of the interface scale, for example, reorganizing the interface layers according to different proportions of composite materials containing different additives.

[0073] Exemplarily, the waterproofing agent in the core layer 100 includes a biomass-based waterproofing agent; the waterproofing agent in the first surface layer 200 includes a metal nanooxide; or, the waterproofing agent in the core layer 100 includes a metal nanooxide; the waterproofing agent in the first surface layer 200 includes a biomass-based waterproofing agent.

[0074] In a preferred embodiment, the waterproofing agent in the core layer 100 includes a biomass-based waterproofing agent, and the waterproofing agent in the first surface layer 200 includes a metal nano-oxide. Thus, the metal nano-oxide is disposed in the surface layer 200, so that the composite board has excellent waterproofness and better flame retardant properties.

[0075] In one embodiment, the biomass-based waterproofing agent is applied by physical layering, and the metal nano-oxide is applied by physical layering.

[0076] Exemplarily, when multiple physical layer stacking is adopted, the first surface layer 200 can be located on opposite sides of the core layer 100, and there is a certain ratio between the first surface layer 200 and the core layer 100 in the three-layer structure. For example, the mass of the first surface layer 200 accounts for 10-60% of the mass of the composite board, and the mass of the core layer 100 accounts for 30-90% of the mass of the composite board.

[0077] Optionally, refer to Figure 6 The composite board further includes a second surface layer 300, which is located on a side of the first surface layer 200 away from the core layer 100, and the second surface layer 300 includes the aforementioned composite material.

[0078] Exemplarily, when multiple physical layer stacking is adopted, the first surface layer 200 can be located on opposite sides of the core layer 100, and the second surface layer 300 is located on the surface of the first surface layer 200 facing away from the core layer 100. The mass of the first surface layer 200 in the five-layer structure accounts for 10-40% of the mass of the composite board, the mass of the second surface layer 300 accounts for 10-50% of the mass of the composite board, and the mass of the core layer 100 accounts for 30-80% of the mass of the composite board.

[0079] The composite board material of the embodiment of the present application can meet the physical and mechanical property requirements of OSB / 4 in a wet state, while realizing the processing and reuse of biomass materials, as well as energy-saving, intelligent and green production of board material manufacturing.

[0080] The third aspect of the present application provides a method for preparing the aforementioned composite board, referring to Figure 7 The schematic flow chart of the preparation method of the composite board is shown, and the preparation method of the composite board includes the following steps.

[0081] S100: mixing wood chips, a biomass-based waterproofing agent and an adhesive to obtain a first mixture.

[0082] It should be noted that the wood chips, biomass-based waterproofing agent and adhesive are consistent with the previous description and will not be elaborated here.

[0083] S200: mixing wood chips, metal nano-oxides and adhesive to obtain a second mixture.

[0084] It should be noted that the metal nano-oxide is consistent with the above description and will not be described in detail here.

[0085] S300: The first mixture and the second mixture are alternately and layered in sequence to obtain a multi-layer board material layer.

[0086] Exemplarily, the method of preparing the first mixture includes adding a biomass-based waterproofing agent and an adhesive to wood chips.

[0087] Exemplarily, the method of preparing the second mixture includes adding metal nano-oxide and adhesive to wood chips.

[0088] It is understandable that the sizes of the wood chips in the first mixture and the second mixture may be the same or different; the moisture content of the wood chips may be the same or different; and the amounts of the wood chips may be the same or different.

[0089] It is understandable that the specific types of the adhesive in the first mixture and the second mixture may be the same or different; the dry weight ratio of the adhesive to the wood chips may be the same or different.

[0090] It can be understood that in the first mixture, the mass of the biomass-based waterproofing agent is 1-10% of the dry weight of the wood chips; in the second mixture, the mass of the metal nano-oxide is 0.1-2.0% of the dry weight of the wood chips.

[0091] In one embodiment, the paving method of the first mixture includes: mixing a paraffin-based material and a lignin-based compound at 40-100° C. to obtain a biomass-based waterproofing agent; and adding the biomass-based waterproofing agent to wood chips to obtain the first mixture.

[0092] Exemplarily, the biomass-based waterproofing agent is heated at 40-100° C. and then sprayed onto the wood chips through a spraying pipe.

[0093] S400: hot pressing the raw material layers of the multi-layer board to obtain a composite board.

[0094] In one embodiment, the temperature of the hot pressing treatment is 120-210°C, for example, 120°C, 140°C, 160°C, 180°C, 200°C or 210°C.

[0095] The present application is further described below in conjunction with specific embodiments. It should be noted that the following embodiments are only used to explain the present application and cannot be understood as limiting the present application.

[0096] It should be noted that, unless otherwise specified, the performance tests in the following embodiments and comparative examples refer to the following operating steps:

[0097] 1. Water absorption thickness expansion rate

[0098] The water absorption thickness expansion rate of the board is tested according to GB / T 41715-2022. The treatment conditions for the water absorption thickness expansion rate are to immerse the specimen in water at room temperature for 2 hours, wipe off the water attached to the surface of the specimen after taking it out, and measure it at room temperature. After the test, immerse the board in water at room temperature for another 22 hours, wipe off the water attached to the surface of the specimen after taking it out, and then test the water absorption thickness expansion rate for 24 hours.

[0099] 2. Static bending strength

[0100] The bending resistance and internal bonding strength are tested in accordance with the national standard GB / T 17657-2013 "Test methods for physical and chemical properties of wood-based panels and veneer wood-based panels". The main tests are the static bending strength and elastic modulus of three-point bending, which is measured by applying a load to the middle of the specimen supported at two points. The static bending strength is determined by the ratio of the bending moment and the bending section modulus of the specimen under the maximum load.

[0101] 3. Internal bonding strength

[0102] Bond the plates together with the clamps using hot melt adhesive, and place them under standard test conditions. After the bonding is firm, conduct the test. Apply load evenly, and destroy the specimen within (60±30)s from the start of loading. Record the maximum load value.

[0103] Example 1

[0104] The method for preparing the composite sheet comprises the following steps:

[0105] Pine wood shavings with a thickness of 0.6 mm, a length of 14-16 cm, a width of 3-5 cm and a moisture content of 10% are sprayed with isocyanate in an amount of 6% of the dry weight of the shavings, and then a biomass-based waterproofing agent with a solid content of 40% is sprayed on the shavings to obtain a core layer material, wherein the biomass-based waterproofing agent is 5% of the dry weight of the shavings.

[0106] Mix nano-alumina with a particle size of 20-40nm and isocyanate with pine wood shavings with a thickness of 0.6mm, a length of 14-16cm, a width of 3-5cm and a moisture content of 10%, and spray them on the pine wood shavings. The amount of nano-alumina added is 5% of the dry weight of the shavings, and the amount of isocyanate added is 6% of the dry weight of the shavings to obtain the surface material.

[0107] The surface material and the core material are physically stacked and laid in a three-layer structure, that is, the surface material, the core material and the surface material are stacked and laid in sequence, and hot-pressed at 180° C. for 8 minutes to obtain a wood-based composite board.

[0108] The water absorption thickness expansion rate of the composite board of this embodiment is 5.28 (0.79) %; the internal bonding strength is 2.03 (0.24) MPa; the static bending strength is 39.21 (1.99) MPa; and the elastic modulus is 6718.12 (507.9) MPa.

[0109] It should be noted that the experimental data in this article is explained by taking the water absorption thickness expansion rate of 5.28 (0.79)% as an example, which means that the water absorption thickness expansion rate is 5.28% and the error is 0.79%. Taking the internal bonding strength of 2.03 (0.24) MPa as an example, the internal bonding strength is 2.03 MPa and the error is 0.24 MPa. The data in each embodiment and comparative example can be understood with reference to the above examples.

[0110] Example 2

[0111] The method for preparing the composite sheet comprises the following steps:

[0112] Mix nano-alumina with a particle size of 20-40nm and isocyanate with pine wood shavings with a thickness of 0.6mm, a length of 14-16cm, a width of 3-5cm and a moisture content of 6-10%, and spray them on the pine wood shavings. The amount of nano-alumina added is 5% of the dry weight of the shavings, and the amount of isocyanate added is 6% of the dry weight of the shavings to obtain the core layer material.

[0113] Pine wood shavings with a thickness of 0.6 mm, a length of 14-16 cm, a width of 3-5 cm, and a moisture content of 6-10% are sprayed with isocyanate in an amount of 6% of the dry weight of the shavings, and then a biomass-based waterproofing agent with a solid content of 40% is sprayed on the shavings to obtain a surface material, and the biomass-based waterproofing agent is 5% of the dry weight of the shavings;

[0114] The surface material and the core material are physically stacked and laid in a three-layer structure, that is, the surface material, the core material and the surface material are stacked and laid in sequence, and hot-pressed at 180° C. for 8 minutes to obtain a wood-based composite board.

[0115] The water absorption thickness expansion rate of the composite board of this embodiment is 4.09 (0.74) %; the internal bonding strength is 3.09 (0.26) MPa; the static bending strength is 46.56 (0.78) MPa; and the elastic modulus is 7171.18 (265.0) MPa.

[0116] Examples 3 to 10: The preparation method of the composite board is basically the same as that of Example 1, except that the material selection and content of each component in the core layer and the surface layer are shown in Table 1 below. The properties of the composite board (including water absorption thickness expansion rate, internal bonding strength, static bending strength and elastic modulus) are also shown in Table 1 below:

[0117] Table 1

[0118]

[0119]

[0120] Comparative Example 1

[0121] The method for preparing the composite sheet comprises the following steps:

[0122] Pine wood shavings with a thickness of 0.6 mm, a length of 14-16 cm, a width of 3-5 cm and a moisture content of 10% are sprayed with isocyanate in an amount of 5% of the dry weight of the shavings. The shavings sprayed with the adhesive are physically stacked and paved, and hot-pressed at 180° C. for 8 minutes to obtain a wood-based composite material.

[0123] The water absorption thickness expansion rate of the composite board of this comparative example is 24.19 (1.16) %; the internal bonding strength is 0.75 (0.03) MPa; the static bending strength is 29.24 (2.12) MPa; and the elastic modulus is 6159.20 (311.4) MPa.

[0124] Comparative Example 2

[0125] The method for preparing the composite sheet comprises the following steps:

[0126] Pine wood shavings with a thickness of 0.6 mm, a length of 14-16 cm, a width of 3-5 cm, and a moisture content of 6-10% are sprayed with isocyanate in an amount of 5% of the dry weight of the shavings, and then a single molten paraffin with a solid content of 40% is sprayed on the shavings to obtain a surface material;

[0127] Pine wood shavings with a thickness of 0.6 mm, a length of 14-16 cm, a width of 3-5 cm and a moisture content of 6-10% are sprayed with isocyanate in an amount of 5% of the dry weight of the shavings to obtain a surface material.

[0128] The surface layer material and the core layer material are physically stacked and laid in a three-layer structure, and are hot-pressed at 180° C. for 8 minutes to obtain a wood-based composite material.

[0129] The water absorption thickness expansion rate of the composite board of this comparative example is 15.97 (2.08)%; the internal bonding strength is 0.65 (0.09) MPa; the static bending strength is 28.74 (1.06) MPa; and the elastic modulus is 5752.08 (177.6) MPa. The basic principles of the present application are described above in conjunction with specific embodiments. However, it should be pointed out that the advantages, strengths, effects, etc. mentioned in the present application are only examples and not limitations. It cannot be considered that these advantages, strengths, effects, etc. must be possessed by each embodiment of the present application. In addition, the specific details disclosed above are only for the purpose of illustration and ease of understanding, and are not limiting. The above details do not limit the present application to the use of the above specific details to be implemented.

[0130] The above description has been given for the purpose of illustration and description. In addition, this description is not intended to limit the embodiments of the present application to the forms disclosed herein. Although multiple example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, changes, additions and sub-combinations thereof.

Claims

1. A composite material, characterized in that: include: Wood chips, functional additives and adhesives; Wherein, the functionalized auxiliary agent includes a biomass-based waterproofing agent and / or a metal nano-oxide.

2. The composite material according to claim 1, characterized in that The biomass-based waterproofing agent comprises a paraffin-based material and a lignin-based compound, wherein the lignin-based compound covers at least a portion of the paraffin-based material; Preferably, the lignin-based compound encapsulates the paraffin-based material to form a core-shell structure; Preferably, the paraffin-based material includes at least one of solid paraffin, molten paraffin and paraffin emulsion; Preferably, the lignin-based compound comprises pulp and papermaking byproducts; Preferably, the lignin-based compound comprises at least one of lignin sulfonate, sulfite lignin and sulfate lignin; Preferably, the solid content of the biomass-based waterproofing agent is 20-80%.

3. The composite material according to claim 1, characterized in that The metal nano-oxide comprises at least one of nano-iron oxide, nano-aluminum oxide, nano-copper oxide and nano-titanium oxide; Preferably, the particle size of the metal nano-oxide is 20-50 nm.

4. The composite material according to claim 1, characterized in that The moisture content of the wood shavings is 2-20%; Preferably, the wood shavings have a thickness of 0.4-1.6 mm, a length of 3-25 cm, and a width of 3-10 cm; Preferably, the adhesive comprises at least one of a biomass adhesive, a urea-formaldehyde resin and an isocyanate.

5. The composite material according to claim 1, characterized in that The mass of the biomass-based waterproofing agent is 1-12% of the dry weight of the wood chips; and / or, the mass of the metal nano-oxide is 0.1-5.0% of the dry weight of the wood chips; And / or, the mass of the adhesive is 1-25% of the dry weight of the wood chips.

6. A composite board, characterized in that: include: A core layer, the core layer comprising the composite material according to any one of claims 1 to 5; A first surface layer is located on at least a portion of the surface of the core layer, the first surface layer comprises the composite material according to any one of claims 1 to 5; and crosslinking exists at the interface where the core layer and the first surface layer are connected; The functionalized auxiliary agent in the core layer includes one of a biomass-based waterproofing agent and a metal oxide, and the functionalized auxiliary agent in the first surface layer includes the other of a biomass-based waterproofing agent and a metal oxide.

7. The composite sheet material according to claim 6, characterized in that: The mass of the first surface layer accounts for 10-60% of the mass of the composite board, and the mass of the core layer accounts for 40-90% of the mass of the composite board; Preferably, the biomass-based waterproofing agent is paved by physical stacking, and / or the metal nano-oxide is paved by physical stacking.

8. The composite sheet material according to claim 6, characterized in that: It also includes a second surface layer located on a side of the first surface layer away from the core layer, the second surface layer comprising the composite material according to any one of claims 1 to 5; Preferably, the mass of the first surface layer accounts for 10-40% of the mass of the composite board, the mass of the second surface layer accounts for 10-50% of the mass of the composite board, and the mass of the core layer accounts for 30-80% of the mass of the composite board.

9. A method for preparing a composite board according to any one of claims 6 to 8, characterized in that: include: Mixing wood chips, a biomass-based waterproofing agent, and an adhesive to obtain a first mixture; mixing wood shavings, metal nano-oxides and adhesive to obtain a second mixture; The first mixture and the second mixture are alternately and layered in sequence to obtain a multi-layer board material layer; The composite board is obtained by subjecting the multiple layers of the board material to hot pressing treatment.

10. The preparation method according to claim 9, characterized in that: The temperature of the hot pressing treatment is 120-210°C; Preferably, the paving method of the first mixture comprises: Mixing the paraffin-based material and the lignin-based compound at 40-100° C. to obtain the biomass-based waterproofing agent; The biomass-based waterproofing agent is added to the wood chips.

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