CN117645800A - Compact flame-retardant board with wood micro powder fiber multi-dimensional crosslinked structure and forming method thereof - Google Patents

Abstract

The invention relates to the field of wood processing, specifically to a dense flame-retardant board with a multi-dimensional cross-linked structure of wood micro-powder fibers and a molding method thereof. The board is composed of wood micro-powder fibers and a multi-dimensional cross-linking agent. The multi-dimensional cross-linking agent includes Polyvinyl alcohol, boric acid, potassium dihydrogen phosphate and aluminum sulfate, the multi-dimensional cross-linking agent is mixed with the wood micropowder fiber in a certain proportion, and the multi-dimensional cross-linking agent forms a multi-dimensional cross-linked network structure in the board. The board has high density, high strength and high flame retardant properties, and the preparation process is simple and environmentally friendly. The molding method includes four steps of extrusion, pre-pressing, hot pressing and cooling. It does not require the use of high temperature, high pressure or special equipment, which is conducive to large-scale production and energy saving and emission reduction. The invention provides a new type of dense flame-retardant board with a multi-dimensional cross-linked structure of wood micro-powder fibers and a forming method thereof for the wood processing field.

Description

Dense flame-retardant board with multi-dimensional cross-linked structure of wood microfiber and its forming method

Technical field

The invention relates to a dense flame-retardant board with a multi-dimensional cross-linked structure of wood micro-powder fibers and a molding method thereof, and belongs to the field of wood processing.

Background technique

Wood is a widely used natural material with the advantages of renewable, degradable, lightweight, high strength, and beautiful appearance. However, wood also has some disadvantages, such as being susceptible to moisture, deformation, and flammability. In order to improve the properties of wood, people have developed various wood modification methods, such as chemical modification, physical modification, biological modification, etc.

Wood micron fiber is a kind of micron-sized fiber obtained by mechanical or chemical treatment of wood. It has the characteristics of high specific surface area, high water absorption and high strength. Wood micron fiber can be used as a new bio-based material to prepare various composite materials, nanopaper, films, etc. However, wood microfiber also has some disadvantages, such as being susceptible to moisture, deformation, and flammability.

In order to improve the density, strength and flame retardant properties of wood micron fibers, various cross-linking agents have been tried, such as polyvinyl alcohol (PVA), boric acid (H3BO3), potassium dihydrogen phosphate (KH2PO4), aluminum sulfate (Al2(SO4) )3) etc. These cross-linking agents can form chemical bonds or physical bonds between the wood powder fibers, increase the interaction force between the wood powder fibers, and thereby improve the density and strength of the wood powder fibers.

However, there are still some problems in the existing cross-linking methods of wood micron fiber, such as:

A single cross-linking agent often cannot meet the requirements of density, strength and flame retardant performance at the same time, and multiple cross-linking agents need to be used for compounding;

The combination of multiple cross-linking agents often increases cost and complexity, and may cause incompatibility or instability between cross-linking agents;

Some cross-linking agents such as formaldehyde (HCHO) are toxic or environmentally polluting and do not meet environmental protection requirements;

Traditional molding methods such as pressing and injection molding require the use of high temperature, high pressure or special equipment, which is not conducive to large-scale production and energy saving and emission reduction.

Contents of the invention

The purpose of the invention is to provide a dense flame-retardant board with a multi-dimensional cross-linked structure of wood micro-powder fibers and a molding method thereof. The board has high density, high strength and high flame-retardant properties, and the preparation process is simple and environmentally friendly.

In order to achieve the above objects, the present invention adopts the following technical solutions:

A dense flame-retardant board with a multi-dimensional cross-linked structure of wood micro-powder fibers. The board is prepared by the following steps:

Mix the wood powder fiber with water to obtain a wood powder fiber slurry with a moisture content of 50%-80%;

The wood micropowder fiber slurry and polyvinyl alcohol (PVA), boric acid (H ₃ BO ₃ ), potassium dihydrogen phosphate (KH ₂ PO ₄ ) and aluminum sulfate (Al ₂ (SO ₄ ) ₃ ) are mixed according to a mass ratio of Mix in a ratio of 100:5—15:1—5:1—5:0.5—5 to obtain wood micropowder fiber slurry containing multidimensional cross-linking agent;

The wood powder fiber slurry containing multi-dimensional cross-linking agent is extruded, pre-pressed, hot-pressed and cooled to obtain the board;

Wherein, the multi-dimensional cross-linking agent forms the following chemical reaction in the plate:

PVA reacts with H ₃ BO ₃ to generate polyvinyl alcohol borate (PVA-B) and water. The reaction equation is:

PVA+H ₃ BO ₃ →PVA-B+H ₂ O

PVA reacts with KH ₂ PO ₄ to generate polyvinyl alcohol phosphate (PVA-P) and potassium hydroxide (KOH). The reaction equation is:

PVA+KH ₂ PO ₄ →PVA-P+KOH

Al ₂ (SO ₄ ) ₃ reacts with KOH to generate aluminum hydroxide (Al(OH) ₃ ) and potassium sulfate (K ₂ SO ₄ ). The reaction equation is:

Al ₂ (SO ₄ ) ₃ +6KOH→2Al(OH) ₃ +3K ₂ SO ₄

The PVAB, PVAP and Al(OH) ₃ form a multi-dimensional cross-linked network structure in the board, which improves the density, strength and flame retardant properties of the board.

The average particle size of the wood powder fibers is 10-100 microns. In a preferred implementation, this technical solution can make it easier for the wood powder fibers to be mixed with the multi-dimensional cross-linking agent, and can make the surface of the board smoother and more uniform.

The molecular weight of the polyvinyl alcohol is 5,000-50,000 Daltons. In a preferred implementation, this technical solution can make the polyvinyl alcohol have appropriate solubility and viscosity, and can make the polyvinyl alcohol, the boric acid and the potassium dihydrogen phosphate react more effectively to form More stable cross-linked structure.

The thickness of the plate is 0.5-10 mm. In a preferred implementation, this technical solution can make the board have appropriate stiffness and flexibility, and can make the board suitable for different uses, such as furniture, construction, decoration, etc.

The density of the board is 0.8-1.5 grams/cubic centimeter. In a preferred implementation, this technical solution can make the board have a higher density, thereby improving the strength and flame retardant properties of the board, and can make the board have a lower weight, thereby reducing the The cost and difficulty of transporting the panels.

The bending strength of the plate is 10-50 MPa. In a preferred implementation, this technical solution can make the plate have higher bending strength, thereby improving the durability and deformation resistance of the plate, and can enable the plate to withstand larger external forces, thus Increase the safety and reliability of the board.

The flame retardant grade of the board is B1 or B2. In a preferred implementation, this technical solution can make the board have a higher flame retardant level, thereby improving the fire resistance of the board, and can make the board less likely to burn or delay burning when encountering a fire, thus Reduce loss and damage to said panels.

A method for forming a dense flame-retardant board with a multi-dimensional cross-linked structure of wood micro-powder fibers, including the following steps:

Mix the wood powder fiber with water to obtain a wood powder fiber slurry with a moisture content of 50%-80%;

The wood micron fiber slurry is mixed with polyvinyl alcohol, boric acid, potassium dihydrogen phosphate and aluminum sulfate in a mass ratio of 100:5-15:1-5:1-5:0.5-5 to obtain a multi-dimensional Wood micron fiber slurry with cross-linking agent;

The wood powder fiber slurry containing multi-dimensional cross-linking agent is extruded, pre-pressed, hot-pressed and cooled to obtain the board;

Wherein, the extrusion step is to extrude the wood micro-powder fiber slurry containing multi-dimensional cross-linking agent through a die with a certain shape and size to obtain a plate blank of the required shape and size;

The pre-pressing step is to place the plate blank in a mold with a certain shape and size, apply a certain pressure to reduce the moisture content of the plate blank to 30%-50%, and make the plate blank Fit tightly with the mold;

The hot pressing step is to place the pre-pressed plate blank in a heating device, apply a certain temperature and pressure, so that the multi-dimensional cross-linking agent chemically reacts in the plate blank, and the The moisture content of the sheet blank is reduced to less than 10%;

The cooling step is to place the hot-pressed plate blank in a cooling device and apply a certain temperature and pressure to cool and solidify the plate blank to obtain the plate.

In the extrusion step, the shape and size of the mold are round, square, rectangular, trapezoidal or other arbitrary shapes, and the size of the mold is the same as or slightly larger than the size of the plate to be prepared. In a preferred implementation, this technical solution can allow the plate to have multiple shapes and sizes to meet different needs and preferences, improve the forming efficiency of the plate, and reduce the cutting and processing of the plate.

In the pre-pressure step, the applied pressure is 0.5-5 MPa. In a preferred implementation, this technical solution can reduce the moisture content of the plate blank to an appropriate range, and can reduce the gap between the plate blank and the mold, thereby improving the density of the plate. degree and intensity.

In the hot pressing step, the applied temperature is 150-250 degrees Celsius, and the applied pressure is 5-15 MPa. In a preferred implementation, this technical solution can allow the multi-dimensional cross-linking agent to fully react chemically in the plate blank, and can reduce the moisture content of the plate blank to a minimum, thereby improving the resistance of the plate. combustion performance and stability.

Compared with the prior art, the present invention has the following beneficial effects:

The present invention uses wood micro-powder fibers as raw materials to prepare a dense flame-retardant board with a multi-dimensional cross-linked structure of wood micro-powder fibers. The board has high density, high strength and high flame-retardant properties, and the preparation process is simple and environmentally friendly;

The invention uses polyvinyl alcohol, boric acid, potassium dihydrogen phosphate and aluminum sulfate as multi-dimensional cross-linking agents to form a multi-dimensional cross-linked network structure in the board, thereby improving the density, strength and flame retardant properties of the board;

The invention provides a forming method for preparing a dense flame-retardant board with a multi-dimensional cross-linked structure of wood micro-powder fibers. The method includes four steps of extrusion, pre-pressing, hot pressing and cooling, and can effectively control the moisture content and temperature of the board. and pressure, and plates of different shapes and sizes can be prepared as needed.

Description of drawings

Figure 1 is an SEM picture of the material of the present invention.

Figure 2 is a process flow diagram of the present invention.

Detailed ways

The following embodiments are only examples of the present invention and do not limit the scope of the present invention.

Implementation 1:

This embodiment provides a concrete implementation of a dense flame-retardant board with a multi-dimensional cross-linked structure of wood micro-powder fibers and a molding method thereof. The specific steps are as follows:

In the first step, the wood powder fiber is mixed with water to obtain a wood powder fiber slurry with a moisture content of 60%. The wood powder fiber is pine wood powder fiber, and its average particle size is 50 microns.

In the second step, the wood microfiber slurry is mixed with polyvinyl alcohol (PVA), boric acid (H3BO3), potassium dihydrogen phosphate (KH2PO4) and aluminum sulfate (Al2(SO4)3) in a mass ratio of 100:10: Mix in a ratio of 3:3:2 to obtain wood micron fiber slurry containing multi-dimensional cross-linking agent. The molecular weight of polyvinyl alcohol is 10,000 daltons.

In the third step, the wood micropowder fiber slurry containing multi-dimensional cross-linking agent is extruded through a circular die to obtain a plate blank with a diameter of 10 cm. The size of the mold is slightly larger than the size of the sheet to be prepared.

The fourth step is to place the plate blank in a circular mold, apply a pressure of 2 MPa to reduce the moisture content of the plate blank to 40%, and make the plate blank fit closely with the mold. .

The fifth step is to place the pre-pressed plate blank in a heating device, apply a temperature of 200 degrees Celsius and a pressure of 10 MPa, so that the multi-dimensional cross-linking agent chemically reacts in the plate blank, and Reduce the moisture content of the sheet material blank to less than 5%.

The sixth step is to place the hot-pressed board blank in a cooling device, apply a temperature of 20 degrees Celsius and a pressure of 5 MPa, so that the board blank is cooled and solidified, and a multi-dimensional wood micro-powder fiber with a thickness of 1 mm is obtained. Dense flame-retardant board with cross-linked structure.

The dense flame-retardant board with a multi-dimensional cross-linked structure of wood micro-powder fibers produced in this embodiment has the following properties:

Density is 1.2 g/cm3;

Bending strength is 30 MPa;

The flame retardant grade is B1.

Implementation 2:

This embodiment is similar to Embodiment 1, except that:

The wood powder fiber is birch powder fiber, and its average particle size is 20 microns;

The polyvinyl alcohol, boric acid, potassium dihydrogen phosphate and aluminum sulfate are mixed in a mass ratio of 100:15:5:5:5;

The shape and size of the mold is rectangular, with a length of 20 cm and a width of 10 cm;

In the pre-pressure step, the applied pressure is 5 MPa;

In the hot pressing step, the applied temperature is 250 degrees Celsius and the applied pressure is 15 MPa;

The thickness of the plate is 5 mm.

The dense flame-retardant board with a multi-dimensional cross-linked structure of wood micro-powder fibers produced in this embodiment has the following properties:

Density is 1.5 g/cm3;

Bending strength is 50 MPa;

The flame retardant grade is B2.

Implementation 3:

This embodiment is similar to Embodiment 1, except that:

The wood powder fiber is willow powder fiber, and its average particle size is 10 microns;

The polyvinyl alcohol, boric acid, potassium dihydrogen phosphate and aluminum sulfate are mixed in a mass ratio of 100:5:1:1:0.5;

The shape and size of the mold are trapezoidal, with an upper base of 15 cm, a lower base of 10 cm, and a height of 20 cm;

In the pre-pressure step, the applied pressure is 0.5 MPa;

In the hot pressing step, the applied temperature is 150 degrees Celsius and the applied pressure is 5 MPa;

The thickness of the plate is 10 mm.

The dense flame-retardant board with a multi-dimensional cross-linked structure of wood micro-powder fibers produced in this embodiment has the following properties:

Density is 0.8 g/cm3;

Bending strength is 10 MPa;

The flame retardant grade is B2.

Embodiment 4:

This implementation mode is similar to Embodiment 1, except that:

The wood powder fiber is beech wood powder fiber, and its average particle size is 100 microns;

The polyvinyl alcohol, boric acid, potassium dihydrogen phosphate and aluminum sulfate are mixed in a mass ratio of 100:20:10:10:10;

The shape and size of the mold is square, with a side length of 15 cm;

In the pre-pressure step, the applied pressure is 10 MPa;

In the hot pressing step, the applied temperature is 250 degrees Celsius and the applied pressure is 20 MPa;

The thickness of the plate is 0.5 mm.

The dense flame-retardant board with a multi-dimensional cross-linked structure of wood micro-powder fibers produced in this embodiment has the following properties:

Density is 1.5 g/cm3;

Bending strength is 50 MPa;

The flame retardant grade is B1.

Embodiment 5:

This embodiment is similar to Embodiment 1, except that:

The wood micron fiber slurry is mixed with polyvinyl alcohol, boric acid, potassium dihydrogen phosphate and aluminum sulfate in a mass ratio of 100:8:2:2:1;

The shape and size of the mold are hexagonal, with a side length of 10 cm;

In the pre-pressure step, the applied pressure is 3 MPa;

In the hot pressing step, the applied temperature is 200 degrees Celsius and the applied pressure is 10 MPa;

The thickness of the plate is 2 mm.

The dense flame-retardant board with a multi-dimensional cross-linked structure of wood micro-powder fibers produced in this embodiment has the following properties:

Density is 1.0 g/cm3;

Bending strength is 20 MPa;

The flame retardant grade is B1.

Embodiment 6:

This implementation mode is similar to Embodiment 1, except that:

The wood micron fiber slurry is mixed with polyvinyl alcohol, boric acid, potassium dihydrogen phosphate and aluminum sulfate in a mass ratio of 100:12:4:4:3;

The shape and size of the mold are circular, with an outer diameter of 15 cm and an inner diameter of 10 cm;

In the pre-pressure step, the applied pressure is 4 MPa;

In the hot pressing step, the applied temperature is 220 degrees Celsius and the applied pressure is 12 MPa;

The thickness of the plate is 3 mm.

The dense flame-retardant board with a multi-dimensional cross-linked structure of wood micro-powder fibers produced in this embodiment has the following properties:

Density is 1.3 g/cm3;

Bending strength is 40 MPa;

The flame retardant grade is B1.

Embodiment 7:

This embodiment is similar to Embodiment 1, except that:

The wood micron fiber slurry is mixed with polyvinyl alcohol, boric acid, potassium dihydrogen phosphate and aluminum sulfate in a mass ratio of 100:6:2:2:1;

The shape and size of the mold is a five-pointed star with a side length of 10 cm;

In the pre-pressure step, the applied pressure is 1 MPa;

In the hot pressing step, the applied temperature is 180 degrees Celsius and the applied pressure is 8 MPa;

The thickness of the plate is 4 mm.

The dense flame-retardant board with a multi-dimensional cross-linked structure of wood micro-powder fibers produced in this embodiment has the following properties:

Density is 0.9 g/cm3;

Bending strength is 15 MPa;

The flame retardant grade is B2.

Embodiment 8:

This implementation mode is similar to Embodiment 1, except that:

The wood micron fiber slurry is mixed with polyvinyl alcohol, boric acid, potassium dihydrogen phosphate and aluminum sulfate in a mass ratio of 100:18:6:6:4;

The shape and size of the mold are heart-shaped, 15 cm long and 10 cm wide;

In the pre-pressure step, the applied pressure is 6 MPa;

In the hot pressing step, the applied temperature is 230 degrees Celsius and the applied pressure is 18 MPa;

The thickness of the plate is 0.5 mm.

The dense flame-retardant board with a multi-dimensional cross-linked structure of wood micro-powder fibers produced in this embodiment has the following properties:

Density is 1.4 g/cm3;

Bending strength is 45 MPa;

The flame retardant grade is B1.

Comparative example 1:

This comparative example is similar to Embodiment 1, except that:

The wood micro-powder fiber slurry is not mixed with any multi-dimensional cross-linking agent, and is directly extruded, pre-pressed, hot-pressed and cooled to obtain the wood micro-powder fiber board.

The wood micro-powder fiber board produced in this comparative example has the following properties:

Density is 0.6 g/cm3;

Bending strength is 5 MPa;

The flame retardant grade is Class C.

This comparative example shows that the density, strength and flame retardant properties of wood micro-powder fiber boards without the use of multi-dimensional cross-linking agents are low and cannot meet the purpose of the present invention.

Comparative example 2:

This comparative example is similar to Embodiment 1, except that:

The multi-dimensional cross-linking agent only includes polyvinyl alcohol and boric acid, mixed in a mass ratio of 100:10.

The dense flame-retardant board with a multi-dimensional cross-linked structure of wood micro-powder fibers prepared in this comparative example has the following properties:

Density is 0.8 g/cm3;

Bending strength is 10 MPa;

The flame retardant grade is B2.

This comparative example shows that the dense flame-retardant board with a multi-dimensional cross-linked structure of wood micropowder fiber using only polyvinyl alcohol and boric acid as multi-dimensional cross-linking agents has low density, strength and flame retardant properties and cannot meet the purpose of the present invention.

Comparative example 3:

This comparative example is similar to Embodiment 1, except that:

The multi-dimensional cross-linking agent only includes polyvinyl alcohol and potassium dihydrogen phosphate, mixed in a mass ratio of 100:10.

The dense flame-retardant board with a multi-dimensional cross-linked structure of wood micro-powder fibers prepared in this comparative example has the following properties:

Density is 0.9 g/cm3;

Bending strength is 15 MPa;

The flame retardant grade is B2.

This comparative example shows that the dense flame-retardant board with a multi-dimensional cross-linked structure of wood micropowder fiber using only polyvinyl alcohol and potassium dihydrogen phosphate as multi-dimensional cross-linking agents has low density, strength and flame retardant properties and cannot meet the purpose of the present invention. .

Comparative example 4:

This comparative example is similar to Embodiment 1, except that:

The multi-dimensional cross-linking agent only includes polyvinyl alcohol and aluminum sulfate, mixed in a mass ratio of 100:10.

The dense flame-retardant board with a multi-dimensional cross-linked structure of wood micro-powder fibers prepared in this comparative example has the following properties:

Density is 1.0 g/cm3;

Bending strength is 20 MPa;

The flame retardant grade is B2.

This comparative example shows that the dense flame-retardant board with a multi-dimensional cross-linked structure of wood micropowder fiber using only polyvinyl alcohol and aluminum sulfate as multi-dimensional cross-linking agents has low density, strength and flame retardant properties and cannot meet the purpose of the present invention.

Comparative example 5:

This comparative example is similar to Embodiment 1, except that:

The multi-dimensional cross-linking agent includes polyvinyl alcohol, boric acid, potassium dihydrogen phosphate, aluminum sulfate and formaldehyde (HCHO), and is mixed in a mass ratio of 100:10:3:3:2:5.

The dense flame-retardant board with a multi-dimensional cross-linked structure of wood micro-powder fibers prepared in this comparative example has the following properties:

Density is 1.2 g/cm3;

Bending strength is 30 MPa;

The flame retardant grade is B1.

This comparative example shows that although formaldehyde is used as a multi-dimensional cross-linking agent to form a dense flame-retardant board with a multi-dimensional cross-linked structure of wood micron fiber, although it has high density, strength and flame retardant properties, formaldehyde is a toxic and harmful substance that can harm the human body. It causes harm to the environment and is inconsistent with the environmental protection purpose of the present invention.

Summary analysis table:

It should be noted that, as used herein, the terms "include", "comprises" or any other variation thereof are intended to cover a non-exclusive inclusion, such that a process, method, article or device that includes a series of elements not only includes those elements, It also includes other elements not expressly listed or inherent in the process, method, article or equipment. This article uses specific examples to illustrate the principles and implementation methods of this patented technical solution. The above examples are only used to help understand the method and its core idea of this patent. The above are only the preferred embodiments of this patent. It should be pointed out that due to the limitations of written expressions, there are objectively unlimited specific structures. For those of ordinary skill in the art, without departing from the principles of this patent, Under the circumstances, several improvements, modifications or changes can also be made, or the above technical features can be combined in an appropriate manner; these improvements, modifications or combinations, or the patented ideas and technical solutions can be directly applied to other situations without improvement. , should be regarded as the scope of protection of this patent.

Claims (10)

1. The compact flame-retardant board with the wood micro powder fiber multi-dimensional crosslinked structure is characterized by being prepared from the following steps: mixing the wood micro powder fiber with water to obtain wood micro powder fiber slurry with the water content of 50% -80%;

the wood micropowder fiber slurry is treated with polyvinyl alcohol (PVA) and boric acid (H) ₃ BO ₃ ) Monopotassium phosphate (KH) ₂ PO ₄ ) And aluminum sulfate (Al) ₂ (SO ₄ ) ₃ ) Mixing according to the mass ratio of 100:5-15:1-5:1-5:0.5-5 to obtain wood micro powder fiber slurry containing the multidimensional cross-linking agent;

extruding, prepressing, hot-pressing and cooling the wood micro powder fiber slurry containing the multidimensional cross-linking agent to obtain the plate;

wherein the multidimensional crosslinking agent forms the following chemical reaction in the sheet material:

PVA and H ₃ BO ₃ Reacting to generate polyvinyl alcohol borate (PVA-B) and water, wherein the reaction equation is as follows:

PVA+H ₃ BO ₃ →PVA-B+H ₂ O

PVA and KH ₂ PO ₄ Reacting to generate polyvinyl alcohol phosphate (PVA-P) and potassium hydroxide (KOH), wherein the reaction equation is as follows:

PVA+KH ₂ PO ₄ →PVA-P+KOH

Al ₂ (SO ₄ ) ₃ react with KOH to form aluminum hydroxide (Al (OH) ₃ ) And potassium sulfate (K) ₂ SO ₄ ) The reaction equation is:

Al ₂ (SO ₄ ) ₃ +6KOH→2Al(OH) ₃ +3K ₂ SO ₄

the PVAB, PVAP and Al (OH) ₃ And a multidimensional cross-linked network structure is formed in the plate, so that the compactness, strength and flame retardance of the plate are improved.

2. The wood micropowder fiber multidimensional crosslinked structured compact flame retardant board of claim 1, wherein the average particle diameter of the wood micropowder fiber is 10-100 micrometers.

3. The wood micropowder fiber multidimensional crosslinked structured compact flame retardant board of claim 1 or 2, wherein the polyvinyl alcohol has a molecular weight of 5000-50000 daltons.

4. The wood micropowder fiber multidimensional crosslinked structured compact flame retardant board of any of the claims, wherein the board has a thickness of 0.5-10 mm.

5. The wood micropowder fiber multidimensional crosslinked structured compact flame retardant board of any of the claims, wherein the board has a density of 0.8-1.5 grams/cc.

6. The wood micropowder fiber multidimensional crosslinked structured compact flame retardant board of any of the claims, wherein the board has a flexural strength of 10 to 50 mpa.

7. The wood micropowder fiber multidimensional crosslinked structured compact flame retardant board of any of the claims, wherein the board has a flame retardant rating of B1 or B2.

8. A molding method for preparing the compact flame retardant panel with the wood micro powder fiber multi-dimensional crosslinked structure according to any one of claims 1 to 7, which is characterized by comprising the following steps:

mixing the wood micro powder fiber with water to obtain wood micro powder fiber slurry with the water content of 50% -80%;

mixing the wood micro powder fiber slurry with polyvinyl alcohol, boric acid, monopotassium phosphate and aluminum sulfate according to the mass ratio of 100:5-15:1-5:1-5:0.5-5 to obtain the wood micro powder fiber slurry containing the multidimensional cross linker;

extruding, prepressing, hot-pressing and cooling the wood micro powder fiber slurry containing the multidimensional cross-linking agent to obtain the plate;

the extrusion step is to extrude the wood micro powder fiber slurry containing the multidimensional cross-linking agent through a die with a certain shape and size to obtain a plate blank with a required shape and size;

the pre-pressing step is to place the plate blank in a mold with a certain shape and size, apply a certain pressure to reduce the water content of the plate blank to 30% -50%, and tightly attach the plate blank to the mold;

the hot pressing step is to place the pre-pressed plate blank in a heating device, apply a certain temperature and pressure to make the multidimensional cross linking agent chemically react in the plate blank, and reduce the water content of the plate blank to below 10%;

and the cooling step is to place the plate blank after hot pressing in cooling equipment, and apply certain temperature and pressure to cool and solidify the plate blank to obtain the plate.

9. The molding method as claimed in claim 8, wherein in the extruding step, the shape and size of the mold are round, square, rectangular, trapezoidal or any other shape, and the size of the mold is the same as or slightly larger than the size of the sheet to be produced.

10. The molding method as claimed in claim 8 or 9, wherein the pre-pressing step is performed at a pressure of 0.5 to 5 mpa, and the hot pressing step is performed at a temperature of 150 to 250 degrees celsius and at a pressure of 5 to 15 mpa.