Environment-friendly formaldehyde-free flame-retardant density board and preparation method thereof

Abstract

The application discloses an environment-friendly formaldehyde-free flame-retardant density board, which comprises a board body and a coating plate, a plurality of fixing grooves are formed in the end face and the side wall of the board body, the fixing grooves are symmetrically arranged in pairs, two groups of sliding grooves are formed in the end face of the board body, and the sliding grooves are respectively communicated with the adjacent fixing grooves; and a preparation method of the environment-friendly formaldehyde-free flame-retardant density board is also provided, which comprises the following steps: S1, base material layer preparation, S2, flame-retardant layer preparation and coating, S3, coating plate preparation, and S4, board overall assembly. According to the application, the coating plate and the board body are designed as a separable structure, so that when the coating is damaged or worn, only the coating plate needs to be replaced, the whole board body does not need to be replaced, the cost of maintenance and replacement is effectively reduced, the replacement time is shortened, the maintenance efficiency is improved, and the high cost and the complicated process of replacing the whole board are avoided.

Description

Technical Field

[0001] This invention relates to the field of MDF technology, and in particular to an environmentally friendly, formaldehyde-free, flame-retardant MDF and its preparation method. Background Technology

[0002] Fiberboard, also known as MDF, is a type of engineered wood product made from wood fibers or other plant fibers bonded together with urea-formaldehyde resin or other suitable adhesives.

[0003] In public places such as hotel lobbies, restaurants, shopping malls, and schools, MDF (medium-density fiberboard) is often used as wall decoration panels or display panels. These areas are typically high-traffic areas, and the pushing, pulling, impacts, and frequent friction from people can all cause wear and tear on the coating. Currently, most MDF products on the market have their surface coating integrated with the board material. Once the coating is damaged, the entire board usually needs to be replaced. This not only increases maintenance costs but also reduces the lifespan and maintenance efficiency of the board. Therefore, this paper proposes an environmentally friendly, formaldehyde-free, flame-retardant MDF and its preparation method to address these issues. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by proposing an environmentally friendly, formaldehyde-free, flame-retardant MDF and its preparation method.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] An environmentally friendly, formaldehyde-free, flame-retardant MDF includes a board body and a coated board. The board body has multiple sets of fixing grooves on its end face and sidewalls, arranged symmetrically in pairs. The end face of the board body has two sets of sliding grooves, each communicating with its adjacent fixing groove. The lower end face of the coated board is fixedly connected to multiple sets of fixing blocks (first and second), whose positions correspond one-to-one with the positions of the fixing grooves, and each is slidably connected within its corresponding fixing groove. The two sets of fixing blocks (first) advance into their respective fixing grooves via the two sets of sliding grooves. The sidewalls of the board body have two sets of limiting grooves, each equipped with a limiting mechanism to restrict the position of the coated board.

[0007] Preferably, the limiting mechanism includes a limiting cylinder slidably connected in the limiting groove, one end of the limiting cylinder extending into the fixing groove, and the outer wall of the limiting cylinder being in contact with the side wall of the coating plate.

[0008] Preferably, both sets of fixing blocks are located at the edge of the coating plate and have a certain gap with the edge of the coating plate.

[0009] Preferably, the outer walls of the two sets of fixing blocks one and two, as well as the inner walls of the fixing grooves, are all T-shaped, and the outer walls of fixing blocks one and two are in contact with the inner walls of the fixing grooves.

[0010] Preferably, one end of the limiting cylinder is open, a sliding rod is fixedly connected to the inner wall of the limiting groove, and the limiting cylinder is slidably connected to the outer wall of the sliding rod.

[0011] Preferably, a spring is fixedly connected to one end of the slide rod, and the other end of the spring is fixedly connected to the inner wall of the limiting cylinder.

[0012] Preferably, a lever is fixedly connected to the outer wall of the limiting cylinder, and the side wall of the lever is horizontal with the side wall of the plate body.

[0013] Preferably, the board body is composed of a flame-retardant layer and a substrate layer. The substrate layer is formed by hot pressing of formaldehyde-free resin and wood fiber in a certain proportion under high temperature and high pressure. The flame-retardant layer is made of formaldehyde-free resin and environmentally friendly flame-retardant additives. The flame-retardant layer is sprayed on the outer wall of the substrate layer. The coated board covers the surface of the flame-retardant layer and its outer wall is sprayed with environmentally friendly water-based paint. The coated board is made of environmentally friendly alcohol-free density fiberboard.

[0014] This invention also proposes a method for preparing environmentally friendly formaldehyde-free flame-retardant MDF, comprising the following steps:

[0015] S1, Substrate Layer Preparation

[0016] Raw material preparation: Select wood fibers, screen them to remove impurities and excessively large particles, and ensure that the fiber length is between 1-5mm. Then dry them to control the moisture content at 5-10%. At the same time, prepare formaldehyde-free resin adhesive. Formaldehyde-free resin can be isocyanate resin, etc. Prepare raw materials according to the mass ratio of wood fiber to formaldehyde-free resin of 8-10:1.

[0017] Mixing and molding: The dried wood fibers and formaldehyde-free resin adhesive are thoroughly mixed in a mixer at a speed of 1000-1500 rpm for 10-20 minutes. The mixed material is then poured into a mold and hot-pressed at a temperature of 180-220℃ and a pressure of 3-5 MPa. The hot-pressing time is determined according to the thickness of the board, generally 2-3 minutes per millimeter of thickness, to obtain the initial finished product of the substrate layer.

[0018] S2, Preparation and Coating of Flame Retardant Layer

[0019] Flame retardant mixing: Select environmentally friendly flame retardant additives, such as magnesium hydroxide and aluminum hydroxide, and mix them with formaldehyde-free resin adhesive; the mass ratio of flame retardant additives to formaldehyde-free resin is 3-5:1. Use high-speed mixing equipment to mix at a speed of 1500-2000 rpm for 15-30 minutes to ensure that the flame retardant additives are evenly dispersed in the formaldehyde-free resin to obtain flame retardant coating.

[0020] Coating process: The prepared flame retardant coating is applied to the surface of the substrate layer by spraying or roller coating, with the coating amount controlled at 100-200g / m²; after coating, it is dried at a temperature of 60-80℃ for 2-4 hours to cure the flame retardant layer and obtain a board with a flame retardant layer.

[0021] S3, Coated Plate Preparation

[0022] Board selection: Environmentally friendly alcohol-free MDF is selected as the base material for the coated board, with a thickness of 2-5mm; its surface is sanded to remove surface roughness, and the surface dust is cleaned with a vacuum cleaner after sanding.

[0023] Coating application: Apply environmentally friendly water-based coating to the sanded surface of the environmentally friendly alcohol-free MDF board. Water-based polyurethane coatings are suitable options. First, adjust the coating to a suitable viscosity and dilute it with an appropriate amount of deionized water at a ratio of coating:water = 10:1-2. Use a spray gun for spraying at a pressure of 0.3-0.5 MPa and a distance of 20-30 cm to ensure a uniform coating thickness of 50-100 μm. After spraying, allow the board to air dry at room temperature for 24-48 hours to obtain the finished coated board.

[0024] S4, Overall assembly of sheet metal

[0025] Machining of fixed grooves and sliding grooves: Fixed grooves are machined on the end face and side wall of the plate with flame retardant layer. The fixed grooves are machined by machine milling, and are set symmetrically in pairs. The groove shape is T-shaped, with a groove depth of 5-10mm and a groove width of 8-12mm. Two sets of sliding grooves are machined on the end face of the plate. The sliding grooves are connected to the adjacent fixed grooves. The sliding grooves are 5-8mm wide and have the same depth as the fixed grooves.

[0026] Installation of limiting grooves and limiting mechanism: Two sets of limiting grooves are machined on the side wall of the plate, with a depth of 10-15mm and a width of 8-10mm; the slide rod is installed on the inner wall of the limiting groove, with the length of the slide rod being the same as the depth of the limiting groove; a limiting sleeve is fitted on the slide rod, with one end of the limiting sleeve open; one end of the spring is fixed to the end of the slide rod, and the other end is fixed to the inner wall of the limiting sleeve, so that when the spring is in its natural state, one end of the limiting sleeve extends out of the limiting groove; a lever is installed on the outer wall of the limiting sleeve, with the lever parallel to the side wall of the plate.

[0027] Assembly of the coated plate and the main body: Align the first fixing block (T-shaped structure, size adapted to the fixing groove and sliding groove) on the lower end face of the coated plate with the sliding groove, insert the first fixing block into the sliding groove and push it into the fixing groove. At this time, the second fixing block (also T-shaped structure, located at the edge of the coated plate) is located at the opening of the fixing groove; Move the lever to compress the spring so that the limiting cylinder retracts into the limiting groove, push the coated plate so that the second fixing block is fully inserted into the fixing groove, release the lever, the spring rebounds and the limiting cylinder extends out to lock the second fixing block, completing the assembly.

[0028] The present invention has the following beneficial effects:

[0029] 1. This invention designs the coating plate and the board body as a separable structure, so that when the coating is damaged or worn, only the coating plate needs to be replaced, instead of the entire board body. This effectively reduces the cost of repair and replacement, shortens the replacement time, improves maintenance efficiency, and avoids the high cost and cumbersome process of replacing the entire board body.

[0030] 2. By using formaldehyde-free resin and environmentally friendly materials, this invention not only improves the strength, stability and flame retardant properties of the board itself, but also avoids the release of harmful substances, meeting environmental protection standards. While ensuring safety, it minimizes the impact on the environment, making it particularly suitable for application scenarios with high environmental protection requirements. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the structure of an environmentally friendly, formaldehyde-free, flame-retardant MDF proposed in this invention.

[0032] Figure 2 for Figure 1 Structural diagram.

[0033] Figure 3 for Figure 1 Sectional view of the plate body.

[0034] Figure 4 for Figure 1 Cross-sectional view of the sheet metal body and the coated sheet.

[0035] Figure 5 for Figure 3 Cross-sectional view of the middle limiting cylinder.

[0036] In the diagram: 1. Sheet body; 2. Coated sheet; 3. Fixing groove; 4. Fixing block one; 5. Sliding groove; 6. Fixing block two; 7. Limiting groove; 8. Paddle; 9. Flame retardant layer; 10. Substrate layer; 11. Sliding rod; 12. Limiting cylinder; 13. Spring. Detailed Implementation

[0037] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0038] Reference Figure 1-5An environmentally friendly, formaldehyde-free, flame-retardant MDF board includes a board body 1 and a coated board 2. Multiple sets of fixing grooves 3 are formed on the end face and side walls of the board body 1, arranged symmetrically in pairs. Two sets of sliding grooves 5 are formed on the end face of the board body 1, communicating with the interior of their adjacent fixing grooves 3. Multiple sets of fixing blocks 4 and 6 are fixedly connected to the lower end face of the coated board 2, their positions corresponding one-to-one with the positions of the fixing grooves 3, and slidingly connected within their respective fixing grooves 3. The two sets of fixing blocks 4 advance into their respective fixing grooves 3 via the two sets of sliding grooves 5. Two sets of limiting grooves 7 are formed on the side walls of the board body 1, each equipped with a limiting mechanism to restrict the position of the coated board 2. Due to the separable design of the coated board 2 and the board body 1, when the coating is damaged or worn, only the coated board 2 can be replaced, without replacing the entire board body 1, reducing replacement costs and time and improving maintenance efficiency.

[0039] The limiting mechanism includes a limiting cylinder 12 slidably connected within the limiting groove 7. One end of the limiting cylinder 12 extends into the fixing groove 3. The outer wall of the limiting cylinder 12 is in contact with the side wall of the coating plate 2. Both sets of fixing blocks 6 are located at the edge of the coating plate 2, with a certain gap between them and the edge. The outer walls of the two sets of fixing blocks 4 and 6, as well as the inner wall of the fixing groove 3, are T-shaped. The outer walls of fixing blocks 4 and 6 are in contact with the inner wall of the fixing groove 3. One end of the limiting cylinder 12 is open. A sliding rod 1 is fixedly connected to the inner wall of the limiting groove 7. 1. The limiting cylinder 12 is slidably connected to the outer wall of the slide rod 11. A spring 13 is fixedly connected to the end of the slide rod 11. The other end of the spring 13 is fixedly connected to the inner wall of the limiting cylinder 12. A lever 8 is fixedly connected to the outer wall of the limiting cylinder 12. The side wall of the lever 8 is horizontal with the side wall of the plate body 1. The limiting cylinder 12 can limit the position of the coating plate 2 after it is engaged with the plate body 1, thereby ensuring the stability of the two after installation. The spring 13 can further limit the position of the limiting cylinder 12.

[0040] The board body 1 is composed of a flame-retardant layer 9 and a substrate layer 10. The substrate layer 10 is formed by hot pressing of formaldehyde-free resin and wood fiber in a certain proportion under high temperature and high pressure. The flame-retardant layer 9 is made of formaldehyde-free resin and environmentally friendly flame-retardant additives. The flame-retardant layer 9 is sprayed on the outer wall of the substrate layer 10. The coated board 2 covers the surface of the flame-retardant layer 9 and its outer wall is sprayed with environmentally friendly water-based paint. The coated board 2 is made of environmentally friendly alcohol-free density fiberboard.

[0041] In this invention, the device is used as follows: First, ensure that the coating plate 2 is separated from the plate body 1. Then, align the fixing block 4 of the coating plate 2 with the slide groove 5 and engage the fixing block 4 into the slide groove 5. At this time, the fixing block 6 is located at the opening of the fixing groove 3 and overlaps with it. Then, push the lever 8 downward, compressing the spring 13 and driving the limiting cylinder 12 to slide inward. Then, push the coating plate 2 towards the fixing groove 3. At this time, the fixing block 4 advances from the slide groove 5 into the fixing groove 3 on one side until it is pushed to the state of abutting against the inner wall of the fixing groove 3. Then, release the lever 8. Under the restoring force of the spring 13, drive the limiting cylinder 12 to slide outward, thereby limiting the fixing block 6. The spring 13 provides elasticity to ensure the stability of the limiting cylinder 12. In this way, when the coating plate 2 is worn or damaged, only the coating plate 2 needs to be replaced, instead of replacing the entire plate body 1.

[0042] The substrate layer 10 is formed by high-temperature and high-pressure hot pressing, ensuring the strength and stability of the board body 1. Simultaneously, the formaldehyde-free resin avoids the release of harmful substances, meeting environmental standards. The flame-retardant layer 9 is made of a mixture of formaldehyde-free resin and environmentally friendly flame-retardant additives, which not only improves the flame-retardant performance of the board but also maintains its environmentally friendly characteristics, avoiding harmful components that may be found in common flame-retardant materials. The coated board 2 uses environmentally friendly alcohol-free MDF and is sprayed with environmentally friendly water-based paint, further improving surface durability and wear resistance. It also avoids harmful substances found in traditional solvent-based paints, ensuring safe and efficient performance in various usage environments. The overall design not only enhances the functionality of the board body 1 but also minimizes its environmental impact.

[0043] This invention also proposes a method for preparing environmentally friendly formaldehyde-free flame-retardant MDF, comprising the following steps:

[0044] S1, Substrate Layer Preparation

[0045] Raw material preparation: Select wood fibers, screen them to remove impurities and excessively large particles, and ensure that the fiber length is between 1-5mm. Then dry them to control the moisture content at 5-10%. At the same time, prepare formaldehyde-free resin adhesive. Formaldehyde-free resin can be isocyanate resin, etc. Prepare raw materials according to the mass ratio of wood fiber to formaldehyde-free resin of 8-10:1.

[0046] Mixing and molding: The dried wood fibers and formaldehyde-free resin adhesive are thoroughly mixed in a mixer at a speed of 1000-1500 rpm for 10-20 minutes. The mixed material is then poured into a mold and hot-pressed at a temperature of 180-220℃ and a pressure of 3-5 MPa. The hot-pressing time is determined according to the thickness of the board, generally 2-3 minutes per millimeter of thickness, to obtain the initial finished product of the substrate layer.

[0047] S2, Preparation and Coating of Flame Retardant Layer

[0048] Flame retardant mixing: Select environmentally friendly flame retardant additives, such as magnesium hydroxide and aluminum hydroxide, and mix them with formaldehyde-free resin adhesive; the mass ratio of flame retardant additives to formaldehyde-free resin is 3-5:1. Use high-speed mixing equipment to mix at a speed of 1500-2000 rpm for 15-30 minutes to ensure that the flame retardant additives are evenly dispersed in the formaldehyde-free resin to obtain flame retardant coating.

[0049] Coating process: The prepared flame retardant coating is applied to the surface of the substrate layer by spraying or roller coating, with the coating amount controlled at 100-200g / m²; after coating, it is dried at a temperature of 60-80℃ for 2-4 hours to cure the flame retardant layer and obtain a board with a flame retardant layer.

[0050] S3, Coated Plate Preparation

[0051] Board selection: Environmentally friendly alcohol-free MDF is selected as the base material for the coated board, with a thickness of 2-5mm; its surface is sanded to remove surface roughness, and the surface dust is cleaned with a vacuum cleaner after sanding.

[0052] Coating application: Apply environmentally friendly water-based coating to the sanded surface of the environmentally friendly alcohol-free MDF board. Water-based polyurethane coatings are suitable options. First, adjust the coating to a suitable viscosity and dilute it with an appropriate amount of deionized water at a ratio of coating:water = 10:1-2. Use a spray gun for spraying at a pressure of 0.3-0.5 MPa and a distance of 20-30 cm to ensure a uniform coating thickness of 50-100 μm. After spraying, allow the board to air dry at room temperature for 24-48 hours to obtain the finished coated board.

[0053] S4, Overall assembly of sheet metal

[0054] Machining of fixed grooves and sliding grooves: Fixed grooves are machined on the end face and side wall of the plate with flame retardant layer. The fixed grooves are machined by machine milling, and are set symmetrically in pairs. The groove shape is T-shaped, with a groove depth of 5-10mm and a groove width of 8-12mm. Two sets of sliding grooves are machined on the end face of the plate. The sliding grooves are connected to the adjacent fixed grooves. The sliding grooves are 5-8mm wide and have the same depth as the fixed grooves.

[0055] Installation of limiting grooves and limiting mechanism: Two sets of limiting grooves are machined on the side wall of the plate, with a depth of 10-15mm and a width of 8-10mm; the slide rod is installed on the inner wall of the limiting groove, with the length of the slide rod being the same as the depth of the limiting groove; a limiting sleeve is fitted on the slide rod, with one end of the limiting sleeve open; one end of the spring is fixed to the end of the slide rod, and the other end is fixed to the inner wall of the limiting sleeve, so that when the spring is in its natural state, one end of the limiting sleeve extends out of the limiting groove; a lever is installed on the outer wall of the limiting sleeve, with the lever parallel to the side wall of the plate.

[0056] Assembly of the coated plate and the main body: Align the first fixing block (T-shaped structure, size adapted to the fixing groove and sliding groove) on the lower end face of the coated plate with the sliding groove, insert the first fixing block into the sliding groove and push it into the fixing groove. At this time, the second fixing block (also T-shaped structure, located at the edge of the coated plate) is located at the opening of the fixing groove; Move the lever to compress the spring so that the limiting cylinder retracts into the limiting groove, push the coated plate so that the second fixing block is fully inserted into the fixing groove, release the lever, the spring rebounds and the limiting cylinder extends out to lock the second fixing block, completing the assembly.

[0057] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing an environmentally friendly formaldehyde-free fire-retardant density board, characterized in that, Includes the following steps, S1, Substrate Layer Preparation Raw material preparation: Select wood fibers, screen them to remove impurities and excessively large particles, and ensure that the fiber length is between 1-5mm. Then dry them to control the moisture content at 5-10%. At the same time, prepare formaldehyde-free resin adhesive. The formaldehyde-free resin is isocyanate resin. Prepare the raw materials according to the mass ratio of wood fiber to formaldehyde-free resin of 8-10:

1. Mixing and molding: The dried wood fibers and formaldehyde-free resin adhesive are thoroughly mixed in a mixer at a speed of 1000-1500 rpm for 10-20 minutes. The mixed material is then poured into a mold and hot-pressed at a temperature of 180-220℃ and a pressure of 3-5 MPa. The hot-pressing time is determined according to the thickness of the board, with 2-3 minutes per millimeter of thickness, to obtain the initial finished product of the substrate layer. S2, Preparation and Coating of Flame Retardant Layer Flame retardant mixing: Select environmentally friendly flame retardant additives and mix them with formaldehyde-free resin adhesives; the mass ratio of flame retardant additives to formaldehyde-free resins is 3-5:

1. Use high-speed mixing equipment to mix at a speed of 1500-2000 rpm for 15-30 minutes to ensure that the flame retardant additives are evenly dispersed in the formaldehyde-free resins to obtain flame retardant coatings. Coating process: The prepared flame retardant coating is applied to the surface of the substrate layer by spraying or roller coating, with the coating amount controlled at 100-200g / m²; after coating, it is dried at 60-80℃ for 2-4 hours to cure the flame retardant layer and obtain a board with a flame retardant layer. S3, Coated Plate Preparation Board selection: Use environmentally friendly alcohol-free MDF as the base material for the coated board, with a thickness of 2-5mm; sand the surface to remove surface roughness, and clean the surface dust with a vacuum cleaner after sanding. Coating application: Apply environmentally friendly water-based paint, specifically water-based polyurethane paint, to the sanded surface of the environmentally friendly alcohol-free MDF board. First, adjust the paint to a suitable viscosity and dilute it with an appropriate amount of deionized water at a ratio of paint:water = 10:1-2. Use a spray gun for application, with a spraying pressure of 0.3-0.5 MPa and a spraying distance of 20-30 cm to ensure a uniform coating thickness of 50-100 μm. After spraying, allow the board to air dry at room temperature for 24-48 hours to obtain the finished coated board. S4, Overall assembly of sheet metal Machining of fixed grooves and sliding grooves: Fixed grooves are machined on the end face and side wall of the plate with flame retardant layer. The fixed grooves are machined by mechanical milling, and are set symmetrically in pairs. The groove shape is T-shaped, with a groove depth of 5-10mm and a groove width of 8-12mm. Two sets of sliding grooves are machined on the end face of the plate. The sliding grooves are connected to the adjacent fixed grooves. The sliding grooves are 5-8mm wide and have the same depth as the fixed grooves. Installation of limiting grooves and limiting mechanism: Process two sets of limiting grooves on the side wall of the plate, with a depth of 10-15mm and a width of 8-10mm; install the slide rod on the inner wall of the limiting groove, with the length of the slide rod being the same as the depth of the limiting groove; fit the limiting cylinder on the slide rod, with one end of the limiting cylinder being open, fix one end of the spring to the end of the slide rod, and fix the other end to the inner wall of the limiting cylinder, so that when the spring is in its natural state, one end of the limiting cylinder extends out of the limiting groove; install a lever on the outer wall of the limiting cylinder, with the lever parallel to the side wall of the plate; Assembly of the coated plate and the main body: Align the first fixing block on the lower end face of the coated plate with the slide groove, insert the first fixing block into the slide groove and push it into the fixing groove. At this time, the second fixing block is located at the opening of the fixing groove. Move the lever to compress the spring so that the limiting cylinder retracts into the limiting groove. Push the coated plate so that the second fixing block is completely inserted into the fixing groove. Release the lever, and the spring rebounds so that the limiting cylinder extends out and locks the second fixing block, thus completing the assembly.

2. An environmentally friendly formaldehyde-free fire-retardant density board, characterized in that, The density board is prepared by the density board preparation method as described in claim 1, including a board body (1) and a coated board (2). The end face and side wall of the board body (1) are provided with multiple sets of fixing grooves (3). The multiple sets of fixing grooves (3) are symmetrically arranged in pairs. The end face of the board body (1) is provided with two sets of sliding grooves (5). The two sets of sliding grooves (5) are respectively connected to the interior of their adjacent fixing grooves (3). The lower end face of the coated board (2) is fixedly connected with multiple sets of fixing blocks one (4) and fixing blocks two (6). The positions of the multiple sets of fixing blocks one (4) and fixing blocks two (6) correspond one-to-one with the positions of the multiple sets of fixing grooves (3), and are slidably connected in the corresponding fixing grooves (3). The two sets of fixing blocks one (4) respectively advance into the corresponding fixing grooves (3) through the two sets of sliding grooves (5). The side wall of the board body (1) is provided with two sets of limiting grooves (7). The two sets of limiting grooves (7) are each equipped with a limiting mechanism for limiting the coating board (2). The limiting mechanism includes a limiting cylinder (12) that is slidably connected in the limiting groove (7). One end of the limiting cylinder (12) extends into the fixing groove (3), and the outer wall of the limiting cylinder (12) is in contact with the side wall of the coating plate (2).

3. The environmentally friendly formaldehyde-free flame-retardant density board according to claim 2, characterized in that, Both sets of fixing blocks (6) are located at the edge of the coating plate (2) and there is a certain gap between them and the edge of the coating plate (2).

4. The environmentally friendly formaldehyde-free flame-retardant density board according to claim 3, characterized in that, The outer walls of the two sets of fixing blocks (4) and fixing blocks (6) and the inner wall of the fixing groove (3) are all T-shaped, and the outer walls of fixing blocks (4) and fixing blocks (6) are in contact with the inner wall of the fixing groove (3).

5. The environmentally friendly formaldehyde-free flame-retardant MDF according to claim 4, characterized in that, One end of the limiting cylinder (12) is open, and a sliding rod (11) is fixedly connected to the inner wall of the limiting groove (7). The limiting cylinder (12) is slidably connected to the outer wall of the sliding rod (11).

6. The environmentally friendly formaldehyde-free flame-retardant MDF according to claim 5, characterized in that, A spring (13) is fixedly connected to the end of the slide rod (11), and the other end of the spring (13) is fixedly connected to the inner wall of the limiting cylinder (12).

7. The environmentally friendly formaldehyde-free flame-retardant MDF according to claim 6, characterized in that, The outer wall of the limiting cylinder (12) is fixedly connected to a lever (8), and the side wall of the lever (8) is horizontal with the side wall of the plate body (1).

8. The environmentally friendly formaldehyde-free flame-retardant MDF according to claim 7, characterized in that, The board body (1) is composed of a flame retardant layer (9) and a substrate layer (10). The substrate layer (10) is formed by hot pressing of formaldehyde-free resin and wood fiber in a certain proportion under high temperature and high pressure. The flame retardant layer (9) is made of formaldehyde-free resin and environmentally friendly flame retardant additives. The flame retardant layer (9) is sprayed on the outer wall of the substrate layer (10). The coated board (2) covers the surface of the flame retardant layer (9) and its outer wall is sprayed with environmentally friendly water-based paint. The coated board (2) is made of environmentally friendly alcohol-free density fiberboard.

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