Flame-retardant modification method of wood fiber, non-combustible bionic board and manufacturing process of non-combustible bionic board

Abstract

The invention belongs to the technical field of artificial boards, and particularly discloses a flame-retardant modification method of wood fibers. According to the flame-retardant modification method, wood fibers are sequentially subjected to flame-retardant modification treatment including chitosan attachment, calcium salt dipping and dihydric phosphate dipping, hydroxyapatite is generated on the surfaces of the wood fibers in situ, conventional wood fibers have the effect similar to mineralized wood, and then the wood fibers are endowed with the non-combustible characteristic. The invention further discloses a non-combustible bionic plate made of the flame-retardant modified wood fiber obtained based on the flame-retardant modification method and a manufacturing process of the non-combustible bionic plate. On the basis of the A2-level non-combustible characteristic, the non-combustible bionic plate further has high wood content and shows excellent toughness and breaking strength. And the manufacturing process is simple and can be carried out on an existing conventional plate production line.

Description

Technical Field

[0001] This invention belongs to the field of engineered wood products technology. Specifically, it discloses a method for flame-retardant modification of wood fibers, as well as a non-combustible biomimetic board based on the obtained flame-retardant modified wood fibers and its manufacturing process. Background Technology

[0002] Flame retardancy is an essential performance requirement for engineered wood products.

[0003] There are currently numerous research reports on Class A engineered wood products. For example, Chinese patent CN 117125949A discloses a pre-coated board with a fire performance rating of Class A and its preparation method. This board uses materials with a mass fraction not exceeding 7% and a density of 1.2 g / cm³. 3 ~1.3 g / cm 3 Larch fiber is used as the raw material and matrix to make the substrate. After penetration sealing and UV multi-coating treatment, the flame resistance, beating degree and flexural strength of the wood fiber are improved by acidification, polyimide coating and weak acidification. The three-stage steam curing method of medium temperature and medium pressure, high temperature and high pressure and low temperature and low pressure is used to further improve the flexural strength and flame resistance of the substrate. Then, before the penetration sealing treatment, an activator is applied to the surface of the substrate to enhance the adhesion of the coating on the substrate, which is conducive to further improving the flame resistance and flexural strength of the pre-coated board. The resulting pre-coated board achieves the GB8624 A2 fire rating and a flexural strength of 13.15 MPa.

[0004] For example, Chinese patent CN 108341634A discloses a flame-retardant wood fiberboard and its preparation method, comprising the following raw materials: wood fiber, cement, silicate, magnesium oxide and magnesium sulfate, wherein the weight percentage of wood fiber is 40-50 parts, the weight percentage of cement is 45-55 parts, and the weight percentage of silicate, magnesium oxide and magnesium sulfate is 3-5 parts. The flame-retardant wood fiberboard of the present invention does not require the use of adhesives, and the board can be obtained after demolding. The flame-retardant wood fiberboard of the present invention achieves A2 grade and has good flame-retardant effect.

[0005] For example, Chinese patent CN 111075143A discloses a Class A fire-resistant biomass flooring, comprising a front wear-resistant layer, a substrate layer, and a back balancing layer. The front wear-resistant layer and the substrate layer, and the substrate layer and the back balancing layer, are linked by special impregnated paper. The substrate layer is made of wood fiber, magnesium oxide, magnesium chloride, and other additives, and is formed by molding. This invention provides a fire-resistant biomass flooring whose substrate is made primarily of wood fiber, derived from fast-growing plants, which reduces stress on trees and effectively lowers costs. Furthermore, the substrate contains magnesium oxide and magnesium chloride, and the molding process provides a degree of fire resistance. The outer surface layer is impregnated with special paper, making it waterproof.

[0006] However, conventional A2 grade engineered wood products often have drawbacks such as low wood content, poor wood texture, high surface hardness, and difficulty in direct lamination of impregnated paper. At the same time, the boards are also dense and brittle, which is not conducive to transportation and on-site processing.

[0007] In conclusion, research on continuous flame-retardant treatment of engineered wood products is of practical significance for their promotion and application in high-end scenarios. Summary of the Invention

[0008] To address the shortcomings of existing conventional A2-grade flame-retardant engineered wood panels, such as low wood content, poor wood texture, high surface hardness, and brittleness, the inventors of this invention, based on long-term research on engineered wood panels, have proposed a novel flame-retardant modification method. This method involves flame-retardant modification of wood fibers, generating hydroxyapatite in situ on the fiber surface, giving conventional wood fibers an effect similar to "mineralized wood," thereby endowing them with non-combustible properties. The non-combustible biomimetic board made from this flame-retardant modified wood fiber, while possessing A2-grade non-combustible properties, also has a high wood content, exhibiting excellent toughness and flexural strength.

[0009] The present invention specifically adopts the following technical solution: A first aspect of the present invention provides a method for flame-retardant modification of wood fibers, comprising the steps of: S1. The wood fiber is immersed in an acidic solution of chitosan, and then an alkaline solution is added to allow the chitosan to adhere to the surface of the wood fiber, thereby obtaining a chitosan-wood fiber gel. S2. The chitosan-wood fiber gel is fully impregnated in a calcium salt solution, washed with water and dried to obtain calcium / chitosan-wood fiber. S3. Calcium / chitosan-wood fiber is fully impregnated in dihydrogen phosphate solution to generate hydroxyapatite in situ on the surface of the wood fiber. After separation and drying, flame-retardant modified wood fiber is obtained.

[0010] Optionally, in step S1, the mass ratio of the acidic chitosan solution to the wood fiber is 1~3:20.

[0011] Optionally, in step S1, the mass concentration of chitosan in the acidic solution is 3% to 7%.

[0012] Optionally, in step S1, the acid solution of chitosan is a chitosan-acetic acid solution.

[0013] Furthermore, in the chitosan-acetic acid solution, the volume concentration of acetic acid is 2% to 5%.

[0014] Optionally, in step S1, the mass ratio of alkali solution to wood fiber is 1~3:20.

[0015] Preferably, in step S1, the alkaline solution is water glass.

[0016] Furthermore, the mass concentration of water glass is 30%~35%.

[0017] Using water glass as the source of alkali has several advantages. First, its alkalinity allows chitosan, which dissolves in an acidic environment, to precipitate again and adhere to the surface of wood fibers. It also provides alkaline conditions for the subsequent in-situ formation of hydroxyapatite on the wood fiber surface. Second, water glass has good film-forming properties; its Si-OH groups can form hydrogen bonds with the hydroxyl groups on the wood fibers and chitosan surface, increasing the coating degree of the wood fibers. Furthermore, when heated, the water molecules in the water glass vaporize and expand, exerting an effect similar to an intumescent flame retardant, further improving the flame-retardant properties of the wood fibers. Third, water glass can be used as an adhesive component when the resulting flame-retardant modified wood fibers are applied in wood product processing.

[0018] Optionally, in step S2, the calcium salt solution is a calcium chloride solution.

[0019] Furthermore, the mass concentration of the calcium chloride solution is 18%~24%.

[0020] Generally, in step S2, immersion at room temperature and pressure for 0.5 h to 1 h is sufficient to allow calcium ions in the calcium salt solution to be adsorbed onto the surface of the chitosan-wood fiber gel.

[0021] Optionally, in step S3, the dihydrogen phosphate in the dihydrogen phosphate solution is selected from any one of ammonium dihydrogen phosphate, potassium dihydrogen phosphate, and sodium dihydrogen phosphate, or a mixture of at least two in any proportion.

[0022] Optionally, in step S3, the mass concentration of the dihydrogen phosphate solution is 12% to 20%.

[0023] Generally, in step S3, immersion at room temperature and pressure for 0.1 h to 0.5 h will generate hydroxyapatite in situ.

[0024] The flame-retardant modification method for wood fibers provided by this invention firstly utilizes the fact that the amino and hydroxyl groups on the chitosan molecular chain contain lone pairs of electrons, which can act as electron donors (Lewis bases), while Ca... 2+ As a hard acid, Ca can form stable coordinate bonds with Lewis bases (groups containing O or N). 2+It can chelate with multiple amino / hydroxyl groups on the chitosan chain, thus becoming fixed inside the chitosan gel. During this process, the hydrogen bonds formed between the amino and hydroxyl groups and water in the chitosan gel are broken, and the bound water is expelled, providing sufficient reaction space for subsequent contact with dihydrogen phosphate ions to ensure the in-situ formation of hydroxyapatite; finally, with the help of the alkaline environment provided by the chitosan attachment, Ca... 2+ Hydroxyapatite is generated in situ on the outside of wood fibers by reacting with dihydrogen phosphate, thereby coating the wood fibers and giving them a similar effect to "mineralized wood", thus endowing them with non-flammable properties.

[0025] In a second aspect, the present invention provides a non-combustible biomimetic board based on the above-mentioned flame-retardant modified wood fiber, which is obtained by impregnating the above-mentioned flame-retardant modified wood fiber with an acidic solution of magnesium salt, fully mixing magnesium oxide and lightweight inorganic additives, and finally laying, pressing and curing.

[0026] Optionally, the magnesium salt in the acidic solution of the magnesium salt is selected from either magnesium sulfate or magnesium chloride, or a mixture of the two.

[0027] Optionally, in the acidic solution of magnesium salt, the mass concentration of magnesium salt is 15% to 20%.

[0028] Optionally, in the acidic solution of the magnesium salt, the acid is selected from any one of phosphoric acid, oxalic acid, and citric acid, or a mixture of at least two in any proportion.

[0029] Optionally, in the acidic solution of the magnesium salt, the mass concentration of the acid is 0.1% to 0.5%.

[0030] Optionally, the magnesium oxide is lightly calcined magnesium oxide with an activity of 60% to 70%.

[0031] Optionally, the mass of magnesium oxide is 1 to 1.2 times the mass of the acidic magnesium salt in the magnesium salt solution.

[0032] Optionally, the lightweight inorganic additive is selected from any one of bentonite, expanded vermiculite, and expanded perlite, or a mixture of at least two in any proportion.

[0033] Optionally, the mass of the light inorganic additive is 0.3 to 1 times the mass of magnesium oxide.

[0034] Optionally, the mass of the flame-retardant modified wood fiber is 1.6 to 3 times the mass of magnesium oxide.

[0035] A third aspect of the present invention provides a manufacturing process for the above-mentioned non-combustible biomimetic board, comprising the steps of: Q1. The flame-retardant modified wood fiber is fully impregnated in an acidic solution of magnesium salts, and then magnesium oxide and light inorganic additives are added and mixed evenly to obtain the slab raw material. Q2. The slab raw material is subjected to at least laying, pressing and curing to obtain non-combustible biomimetic board.

[0036] Optionally, in step Q1, the magnesium salt in the acidic solution is selected from either magnesium sulfate or magnesium chloride, or a mixture of both.

[0037] Optionally, in step Q1, the mass concentration of magnesium salt in the acidic solution of magnesium salt is 15% to 20%.

[0038] Optionally, in step Q1, the acid in the acidic solution of the magnesium salt is selected from any one of phosphoric acid, oxalic acid, and citric acid, or a mixture of at least two in any proportion.

[0039] Optionally, in step Q1, the mass concentration of the acid in the acidic solution of the magnesium salt is 0.1% to 0.5%.

[0040] Optionally, in step Q1, the magnesium oxide is lightly calcined magnesium oxide with an activity of 60% to 70%.

[0041] Optionally, in step Q1, the mass of magnesium oxide is 1 to 1.2 times the mass of magnesium salt in the acidic solution of magnesium salt.

[0042] Optionally, in step Q1, the lightweight inorganic additive is selected from any one of bentonite, expanded vermiculite, and expanded perlite, or a mixture of at least two in any proportion.

[0043] Optionally, in step Q1, the mass of the light inorganic additive is 0.3 to 1 times the mass of magnesium oxide.

[0044] Optionally, in step Q1, the mass of the flame-retardant modified wood fiber is 1.6 to 3 times the mass of magnesium oxide.

[0045] Optionally, in step Q2, the pressing conditions are: unit pressure of 3 MPa to 5 MPa, temperature of 25℃ to 95℃, and time of 0.5 h to 24 h.

[0046] Optionally, in step Q2, the curing conditions are: curing at 75% RH~85% RH humidity for 3 to 5 days, and then curing at 50% RH~65% RH humidity for 3 to 5 days.

[0047] Generally, drying is required after maintenance.

[0048] Optionally, the drying conditions are: drying at 60℃~70℃ for 12 h~36 h.

[0049] The pressing, curing, and drying conditions described above are all standard process parameters for biomimetic boards.

[0050] The non-combustible biomimetic board provided by this invention, on the one hand, uses magnesium cementitious material as a binder, which can further provide an alkaline environment for the in-situ formation of hydroxyapatite in the flame-retardant modified wood fibers. Simultaneously, the curing reaction of the magnesium cementitious material is an exothermic reaction, which can further promote the formation of hydroxyapatite and increase the coverage of hydroxyapatite on the surface of the wood fibers, thereby significantly improving the flame-retardant performance. On the other hand, the addition of lightweight inorganic additives can effectively adsorb moisture in the raw materials of the board blank, improve the early strength of the air-hardening magnesium cementitious material, and its loose and porous characteristics can effectively reduce the density of the finished board, resulting in a lightweight effect.

[0051] At the same time, the in-situ generated hydroxyapatite's encapsulation effect on wood fibers ensures that the obtained non-combustible biomimetic board achieves a higher wood content while maintaining A2-level non-combustible performance, thus exhibiting excellent toughness.

[0052] The manufacturing process of the non-combustible biomimetic board provided by this invention is simple, can be integrated into existing conventional board production lines, and has low manufacturing costs. Detailed Implementation

[0053] The present invention will be described in detail below through examples and comparative examples. Unless otherwise specified, the methods used in the following examples are conventional; the reagents and materials used are commercially available unless otherwise specified.

[0054] Example 1 This embodiment provides a method for flame-retardant modification of wood fibers, which specifically includes the following steps: Weigh 10 kg of wood fiber, add 0.5 kg of chitosan-acetic acid solution (2 vol% acetic acid, 3 wt% chitosan), stir evenly, add 0.5 kg of 35 wt% water glass, stir evenly, and then impregnate in 18 wt% calcium chloride solution at room temperature and pressure for 1 h. After washing and drying, impregnate in 12 wt% potassium dihydrogen phosphate solution at room temperature and pressure for 0.5 h. After filtration and drying, obtain 20 kg of flame-retardant modified wood fiber.

[0055] Example 2 This embodiment provides a method for flame-retardant modification of wood fibers, which specifically includes the following steps: Weigh 12 kg of wood fiber, add 1.8 kg of chitosan-acetic acid solution (5 vol% acetic acid, 7 wt% chitosan), stir well, then add 1.8 kg of 35 wt% water glass, stir well, and impregnate in 24 wt% calcium chloride solution at room temperature and pressure for 0.5 h. After washing and drying, impregnate in 20 wt% potassium dihydrogen phosphate solution at room temperature and pressure for 0.1 h. After filtration and drying, obtain 24 kg of flame-retardant modified wood fiber.

[0056] Example 3 This embodiment provides a method for flame-retardant modification of wood fibers, which specifically includes the following steps: Weigh 12 kg of wood fiber, add 1.2 kg of chitosan-acetic acid solution (3 vol% acetic acid, 5 wt% chitosan), stir well, then add 1.2 kg of 33 wt% water glass, stir well, and impregnate in 20 wt% calcium chloride solution at room temperature and pressure for 0.7 h. After washing and drying, impregnate in 16 wt% potassium dihydrogen phosphate solution at room temperature and pressure for 0.3 h. After filtration and drying, obtain 23 kg of flame-retardant modified wood fiber.

[0057] The flame-retardant modified wood fibers obtained by the flame-retardant modification method of wood fibers provided in the above embodiments can be used to prepare various non-combustible wood products.

[0058] The following embodiments provide a non-combustible biomimetic board based on the flame-retardant modified wood fiber obtained in the above embodiments and its manufacturing process.

[0059] Example 4 This embodiment uses the flame-retardant modified wood fiber obtained in Example 1 above as the wood fiber raw material to provide a non-combustible biomimetic board and its manufacturing process.

[0060] First, the flame-retardant modified wood fiber obtained in Example 1 was fully impregnated in 12.5 kg of magnesium sulfate-citric acid solution (magnesium sulfate mass concentration of 15% and citric acid mass concentration of 0.1%). Then, 12.5 kg of lightly calcined magnesium oxide (activity of 70%) and 10 kg of bentonite were added to the solution and stirred evenly to obtain the slab raw material.

[0061] Specifically, when preparing the magnesium sulfate-citric acid solution, the washing liquid generated after rinsing with water after impregnation with calcium chloride solution in Example 1 is used as a solvent. On the one hand, this can reduce wastewater discharge and improve resource utilization. On the other hand, the calcium chloride in the washing liquid also has a coagulation-promoting effect on the magnesium cementitious material (i.e., the cementitious system formed by magnesium sulfate, magnesium oxide, and water) in the non-combustible biomimetic board, which can shorten the forming time of the board.

[0062] Then, the slab raw material is laid, pressed (unit pressure 3 MPa, 25℃, 24 h), cured (3 d at 75% RH, then 5 d at 50% RH), dried (60℃, 36 h), and cut to obtain a non-combustible biomimetic board.

[0063] That is, this embodiment provides a non-combustible biomimetic board, which is obtained by impregnating the flame-retardant modified wood fiber obtained in Example 1 with magnesium sulfate-citric acid solution, fully mixing magnesium oxide and bentonite, and finally laying, pressing and curing.

[0064] Example 5 This embodiment uses the flame-retardant modified wood fiber obtained in Example 2 above as the wood fiber raw material to provide a non-combustible biomimetic board and its manufacturing process.

[0065] First, the flame-retardant modified wood fiber obtained in Example 2 was fully impregnated in 3.7 kg of magnesium chloride-phosphoric acid solution (magnesium chloride mass concentration of 20% and phosphoric acid mass concentration of 0.5%), and then 8 kg of lightly calcined magnesium oxide (activity of 60%) and 2.4 kg of expanded vermiculite were added. After stirring evenly, slab raw material was obtained.

[0066] Specifically, when preparing the magnesium chloride-phosphoric acid solution, the washing liquid generated by rinsing with water after impregnation with calcium chloride solution in Example 2 is used as the solvent.

[0067] Then, the slab raw material is laid, pressed (unit pressure 5 MPa, 90℃, 0.5 h), cured (5 d at 85% RH, then 3 d at 50% RH), dried (70℃, 12 h), and cut to obtain a non-combustible biomimetic board.

[0068] That is, this embodiment provides a non-combustible biomimetic board, which is obtained by impregnating the flame-retardant modified wood fiber obtained in Example 2 with magnesium chloride-phosphoric acid solution, fully mixing magnesium oxide and expanded vermiculite, and finally laying, pressing and curing.

[0069] Example 6 This embodiment uses the flame-retardant modified wood fiber obtained in Example 3 above as the wood fiber raw material to provide a non-combustible biomimetic board and its manufacturing process.

[0070] First, the flame-retardant modified wood fiber obtained in Example 3 was fully impregnated in 11 kg of magnesium chloride-oxalic acid solution (magnesium chloride mass concentration of 18% and oxalic acid mass concentration of 0.3%), and then 12 kg of lightly calcined magnesium oxide (activity of 65%) and 6 kg of expanded perlite were added. After stirring evenly, slab raw material was obtained.

[0071] Specifically, when preparing the above magnesium chloride-oxalic acid solution, the washing liquid generated by rinsing with water after impregnation with calcium chloride solution in Example 3 is used as the solvent.

[0072] Then, the slab raw material is laid, pressed (unit pressure 4 MPa, 40℃, 15 h), cured (4 d at 85% RH, then 4 d at 60% RH), dried (65℃, 24 h), and cut to obtain a non-combustible biomimetic board.

[0073] That is, this embodiment provides a non-combustible biomimetic board, which is obtained by impregnating the flame-retardant modified wood fiber obtained in Example 3 with magnesium chloride-oxalic acid solution, fully mixing magnesium oxide and expanded perlite, and finally laying, pressing and curing.

[0074] To verify the effect of the flame-retardant modified wood fiber obtained by the flame-retardant modification method of wood fiber provided in the above embodiments of the present invention on the performance of the board, the following comparative experiment was conducted.

[0075] Comparative Example 1 The similarities between this comparative example and Example 6 will not be repeated here; only the differences from Example 6 will be described. The difference between this comparative example and Example 6 is that a mixture of 12 kg of wood fiber and 1.2 kg of 33 wt% water glass is used instead of the flame-retardant modified wood fiber obtained in Example 3; that is, hydroxyapatite is not generated in situ on the surface of the wood fiber, but only water glass is attached; the rest is the same as described in Example 6, and a biomimetic board is obtained.

[0076] Comparative Example 2 The similarities between this comparative example and Example 6 will not be repeated here; only the differences from Example 6 will be described. The difference between this comparative example and Example 6 is that the modified wood fiber prepared by the following method replaces the flame-retardant modified wood fiber obtained in Example 3.

[0077] Specifically, 12 kg of wood fiber was weighed and 1.2 kg of chitosan-acetic acid solution (3 vol% acetic acid, 5 wt% chitosan) was added. After stirring evenly, the mixture was immersed in 20 wt% calcium chloride solution at room temperature and pressure for 0.7 h. After washing and drying, the mixture was immersed in 16 wt% potassium dihydrogen phosphate solution at room temperature and pressure for 0.3 h. After filtration and drying, modified wood fiber was obtained.

[0078] That is, hydroxyapatite was not generated in situ on the surface of the wood fiber, but only chitosan was attached.

[0079] The rest are described in Example 6, and a biomimetic board is obtained.

[0080] Comparative Example 3 The similarities between this comparative example and Example 6 will not be repeated here; only the differences from Example 6 will be described. The difference between this comparative example and Example 6 is that expanded perlite was not added; otherwise, it follows the same procedure as in Example 6 to obtain a biomimetic board.

[0081] The density and flexural strength of the biomimetic boards obtained in Examples 4-6 and Comparative Examples 1-3 were compared with the specifications of GB / T 33544-2017 "Magnesium Oxide Flat Plates". The calorific value was determined according to the requirements of A2 in GB 8624-2012 "Classification of Combustion Performance of Building Materials and Products", that is, the total calorific value PCS ≤ 3.0 MJ / kg.

[0082] The performance data of the biomimetic plates obtained in Examples 4-6 and Comparative Examples 1-3 are shown in Table 1 below.

[0083] Table 1 Performance data of the biomimetic panels obtained in Examples 4-6 and Comparative Examples 1-3 Testing items <![CDATA[Density / kg·m -3 > Flexural strength / MPa <![CDATA[Calorific value of combustion / MJ·kg -1 > Example 4 1090 24 1.2 Example 5 960 17 2.4 Example 6 1020 21 1.9 Comparative Example 1 1010 12 5.6 Comparative Example 2 1040 16 4.3 Comparative Example 3 1330 17 3.2 Standard requirements ＞1100 ≥10.0 ≤3.0 As can be seen from the data in Table 1, in Examples 4-6, with appropriate raw material ratios, the non-combustible biomimetic board meets the A2 grade requirements of GB8624-2012 "Classification of Combustion Performance of Building Materials and Products", its flexural strength is much higher than the requirements of GB / T 33544-2017 "Magnesium Oxide Flat Board", and its density is less than 1100 kg / m³. 3 It is characterized by being lightweight and high-strength.

[0084] A comparison of Comparative Example 1 and Example 6 shows that without hydroxyapatite treatment, the calorific value of the finished board reaches 5.6 MJ / kg, failing to meet the A2 grade requirement. This is because hydroxyapatite adheres to the surface of the wood fibers, which on the one hand prevents direct contact between the wood fibers and the flame, improving the flame retardant properties of the wood fibers; on the other hand, it isolates the wood fibers from air, promoting charring and thus reducing their calorific value.

[0085] A comparison of Comparative Example 2 and Example 6 shows that without water glass treatment, the calorific value of the finished board reached 4.3 MJ / kg, failing to meet the A2 grade requirement. This is because the alkalinity of water glass allows chitosan to form a gel, adhering to the surface of the wood fibers, thereby increasing the coverage of the hydroxyapatite generated in the subsequent reaction on the wood fiber surface. Simultaneously, water glass possesses flame-retardant properties; the water molecules vaporize upon heating, exhibiting intumescent flame-retardant characteristics, further enhancing the flame-retardant performance of the finished board.

[0086] A comparison of Comparative Example 3 and Example 6 shows that the slab without inorganic fillers has a high density, which is detrimental to the transportation and processing of the slab. Meanwhile, the inorganic fillers also have flame-retardant and gas-barrier properties, reducing the calorific value of the slab.

[0087] Meanwhile, in Comparative Examples 1 and 2, the inability to generate hydroxyapatite to coat the wood fibers in situ resulted in combustion performance failing to reach the A2 rating. Conversely, to achieve this combustion performance, the wood fiber content should at least be reduced. Lower wood fiber content leads to reduced toughness in the resulting biomimetic board, while higher wood fiber content acts as a reinforcing structure, improving the board's toughness.

[0088] Furthermore, in Comparative Examples 1 and 2, the inability to generate hydroxyapatite in situ hindered its ability to improve the compatibility of wood fiber and inorganic adhesive (i.e., magnesium cementitious material) with sodium silicate in water glass, thus reducing the flexural strength of the non-combustible biomimetic board. In Comparative Example 3, the lack of expanded perlite prevented the system from absorbing moisture, thus hindering early strength development and affecting the flexural strength of the resulting biomimetic board.

[0089] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for flame-retardant modification of wood fibers, characterized in that, Including the following steps: S1. The wood fiber is immersed in an acidic solution of chitosan, and then an alkaline solution is added to allow the chitosan to adhere to the surface of the wood fiber, thereby obtaining a chitosan-wood fiber gel. S2. The chitosan-wood fiber gel is fully impregnated in a calcium salt solution, washed with water and dried to obtain calcium / chitosan-wood fiber; S3. The calcium / chitosan-wood fiber is fully impregnated in a dihydrogen phosphate solution to generate hydroxyapatite in situ on the surface of the wood fiber. After separation and drying, flame-retardant modified wood fiber is obtained.

2. The flame-retardant modification method according to claim 1, characterized in that, In step S1, the mass ratio of the acidic chitosan solution to the wood fiber is 1~3:

20.

3. The flame-retardant modification method according to claim 2, characterized in that, In step S1, the chitosan mass concentration in the acidic solution of chitosan is 3% to 7%.

4. The flame-retardant modification method according to claim 2, characterized in that, In step S1, the acid solution of chitosan is a chitosan-acetic acid solution.

5. The flame-retardant modification method according to any one of claims 1 to 4, characterized in that, In step S1, the mass ratio of the alkali solution to the wood fiber is 1~3:

20.

6. The flame-retardant modification method according to claim 5, characterized in that, In step S1, the alkaline solution is water glass.

7. The flame-retardant modification method according to claim 1, characterized in that, In step S2, the calcium salt solution is a calcium chloride solution.

8. The flame-retardant modification method according to claim 1, characterized in that, In step S3, the dihydrogen phosphate in the dihydrogen phosphate solution is selected from any one of ammonium dihydrogen phosphate, potassium dihydrogen phosphate, and sodium dihydrogen phosphate, or a mixture of at least two in any proportion.

9. A non-combustible biomimetic panel, characterized in that, Flame-retardant modified wood fibers obtained by any one of the flame-retardant modification methods described in claims 1 to 8 are impregnated with an acidic solution of magnesium salts, and fully mixed with magnesium oxide and lightweight inorganic additives, and finally laid, pressed and cured. Wherein, the mass of the magnesium oxide is 1 to 1.2 times the mass of the acidic magnesium salt in the magnesium salt solution; the mass of the light inorganic additive is 0.3 to 1 times the mass of the magnesium oxide; and the mass of the flame-retardant modified wood fiber is 1.6 to 3 times the mass of the magnesium oxide.

10. The non-combustible biomimetic panel according to claim 9, characterized in that, The magnesium salt in the acidic solution of the magnesium salt is selected from any one of magnesium sulfate and magnesium chloride, or a mixture of the two. And / or, in the acidic solution of the magnesium salt, the mass concentration of the magnesium salt is 15% to 20%; And / or, the magnesium oxide is lightly calcined magnesium oxide with an activity of 60% to 70%.

11. The manufacturing process of the non-combustible biomimetic board as described in claim 9 or 10, characterized in that, Including the following steps: Q1. The flame-retardant modified wood fiber is fully impregnated in the acidic solution of the magnesium salt, and then the magnesium oxide and the light inorganic additives are added and mixed evenly to obtain the slab raw material. Q2. The slab raw material is subjected to at least laying, pressing and curing to obtain the non-combustible bionic board.