High dimensional stability flame-retardant wood panels, their preparation and application

Abstract

A high-dimensional stability flame-retardant wood-based panel, its preparation, and its application are disclosed. The preparation includes: placing the wood-based panel in an impregnation tank and injecting an aqueous solution of branched polyethyleneimine; removing the wood-based panel and drying it to allow the amino groups on the branched polyethyleneimine to undergo a grafting reaction with the hydroxyl groups on the wood; placing the wood-based panel in an impregnation tank and injecting an aqueous solution of 3-aminopropyltriethoxysilane; removing the wood-based panel and drying it to allow the unreacted amino groups on the branched polyethyleneimine grafted onto the wood to chemically react with the hydroxyl groups on the phosphate; and placing the wood-based panel in an impregnation tank and injecting an aqueous solution of 3-aminopropyltriethoxysilane to chemically react with the unreacted hydroxyl groups on the phosphate that have reacted on the branched polyethyleneimine to chemically react with the amino groups on the 3-aminopropyltriethoxysilane. This provides a wood-based panel that simultaneously satisfies flame-retardant properties and high dimensional stability.

Description

Technical Field

[0001] This invention relates to the field of wood panel production, specifically to a high-dimensional stability flame-retardant wood panel, its preparation and application, and more specifically, to a high-dimensional stability flame-retardant wood panel and its preparation method, the application of the flame-retardant wood panel in the preparation of flooring or cabinet door panels, and a high-dimensional stability flame-retardant cabinet door panel and its preparation method. Background Technology

[0002] Moisture changes affect the dimensions of wood; for example, wood expands when it absorbs moisture and shrinks when it loses moisture. This effect is particularly pronounced when long planks are used, such as for flooring, and is further amplified when long planks, especially whole planks, are used vertically, such as for cabinet doors.

[0003] On the other hand, in order to make wood products have flame-retardant properties, when flame-retardant components are added to the wood, the free flame-retardant components will increase the migration of moisture, further damaging the dimensional stability of the board. Summary of the Invention

[0004] In view of the above problems, this invention proposes a wood board that simultaneously satisfies flame retardant properties and high dimensional stability, and further proposes its preparation and related applications.

[0005] The first aspect provides a method for preparing a flame-retardant wood board with high dimensional stability. The method includes: (1) placing the wood board in a first impregnation tank, evacuating to a negative pressure of -0.15 to -0.1 MPa and maintaining it for 10 to 20 minutes, injecting a branched polyethyleneimine aqueous solution with a molecular weight of 800 to 1000 and a concentration of 0.4 to 1.2 mol / L into the impregnation tank until it is at least submerged in the wood board, pressurizing it to 0.5 to 1.0 MPa and maintaining it for 1 to 2 hours, then taking out the wood board and placing it in a drying oven, drying it at 60 to 80°C for 3 to 4.5 hours, so that the amino groups on the branched polyethyleneimine and the hydroxyl groups on the wood undergo a grafting reaction.

[0006] The method further includes: (2): placing the dried wood board from (1) into the second impregnation tank, evacuating to a negative pressure of -0.15 to -0.1 MPa and maintaining it for 20 to 30 minutes, injecting a phosphoric acid aqueous solution with a concentration of 12 to 35 mol / L into the impregnation tank until it at least covers the wood board, pressurizing it to 0.5 to 1.0 MPa and maintaining it for 5 to 6 hours, then taking out the wood board and placing it in a drying oven, drying it at 40 to 60°C for 20 to 24 hours, so that the unreacted amino groups on the branched polyethyleneimine grafted onto the wood can undergo a grafting reaction with the hydroxyl groups on the phosphoric acid.

[0007] The method further includes: (3): placing the dried wood board from (2) into the third impregnation tank, evacuating to a negative pressure of -0.15 to -0.1 MPa and maintaining it for 30 to 40 minutes, injecting an aqueous solution of 30 to 80 mol / L of 3-aminopropyltriethoxysilane into the impregnation tank until it is at least submerged in the wood board, pressurizing it to 0.5 to 1.0 MPa and maintaining it for 5 to 6 hours, then taking out the wood board and placing it in a drying oven, drying it at 40 to 60°C for 20 to 24 hours, so that the unreacted hydroxyl groups on the phosphoric acid on the branched polyethyleneimine react chemically with the amino groups on the 3-aminopropyltriethoxysilane, and then taking out the wood board and placing it at room temperature for more than 10 hours.

[0008] Preferably, the concentration of the phosphoric acid aqueous solution injected into the impregnation tank in (2) is 35 mol / L, and the concentration of the 3-aminopropyltriethoxysilane aqueous solution injected into the impregnation tank in (3) is 70 mol / L.

[0009] The second aspect provides a high-dimensional stability flame-retardant wood board, which is prepared by any of the above-described preparation methods.

[0010] According to the present invention, the migration and loss of moisture in wood are the main causes of wood deformation, warping, and poor dimensional stability. The addition of PEI (Polyethylenimine) reacts with the hydroxyl groups of wood, reducing the wood's own water absorption effect on the one hand, and creating a steric hindrance effect in the multi-layered pore structure of wood through the branched structure of PEI, thus limiting the migration of free water to a certain extent. Furthermore, the addition of phosphoric acid significantly improves combustion performance and flame retardant efficiency; however, phosphoric acid has a strong hygroscopic effect, which weakens the contribution of PEI to dimensional stability while improving combustion performance. Finally, the addition of a coupling agent brings a stronger steric hindrance effect and a weaker water absorption effect, eliminating the influence of the flame retardant on dimensional stability.

[0011] In particular, 3-aminopropyltriethoxysilane acts as a steric hindrance and a coupling agent, promoting the movement of water molecules and balancing moisture migration. When the humidity is too high, 3-aminopropyltriethoxysilane will hinder the rapid migration of moisture to a certain extent, while when the humidity is too low, it can promote the balance of wood moisture content. On the other hand, the molecular polarity of 3-aminopropyltriethoxysilane affects the bonding and separation of PEI and phosphoric acid.

[0012] Through the synergistic effect of these three additives, an optimized balance is achieved between dimensional stability and combustion performance. Regarding combustion performance, the nitrogen in PEI, the phosphorus in phosphate, and the silicon in the silane coupling agent work together to exert a multi-element synergistic effect in flame retardancy, further enhancing flame retardant efficiency during combustion.

[0013] The third aspect provides the application of the aforementioned flame-retardant wood panels in the preparation of flooring or cabinet door panels.

[0014] The fourth aspect provides a method for preparing a flame-retardant cabinet door panel with high dimensional stability. The method includes: (4) preparing two rectangular flame-retardant wood panels of the same predetermined size as side panels; (5) preparing multiple rectangular wood panels of the same predetermined size as unit inner panels, placing the unit inner panels in a fourth impregnation tank, evacuating to a negative pressure of -0.15 to -0.1 MPa and maintaining it for 30 to 40 minutes, injecting a 3-aminopropyltriethoxysilane aqueous solution with a concentration of 50 to 70 mol / L into the impregnation tank until it at least covers the wood panels, and pressurizing. The pressure is increased to 0.5–1.0 MPa and maintained for 5–6 hours. The wood boards are then removed and placed in a drying oven at 40–60°C for 20–24 hours. The dried wood board material is then placed in the fifth impregnation tank, and a vacuum is applied to a negative pressure of -0.15–-0.1 MPa for 20–30 minutes. A 50–70 mol / L phosphoric acid aqueous solution is injected into the impregnation tank until it at least covers the wood boards. The pressure is increased to 0.5–1.0 MPa and maintained for 1–2 hours. The wood boards are then removed and placed in a drying oven at 40–60°C for 10–24 hours. (5) The flame-retardant inner panel is obtained by placing the inner panel of the unit at room temperature for more than 10 hours; (6) Take multiple flame-retardant inner panels obtained in (5) and splice them sequentially along the board surface direction in a way that the long sides are connected to form a square inner panel; The predetermined size of the flame-retardant inner panel ensures that a square inner panel can be spliced ​​by taking multiple flame-retardant inner panels and splicing them sequentially along the board surface direction in a way that the long sides are connected to form a square inner panel; Splice multiple square inner panels and then splice them sequentially along the board surface direction to form a rectangular middle panel, wherein the splicing direction of the flame-retardant inner panels of each two adjacent square inner panels is perpendicular to each other. Straight; splice one long side of the side panel prepared in step (4) along the board surface direction on the two long sides of the middle board to form a cabinet door panel; the predetermined size of the flame-retardant wood board ensures that its long side is equal to the long side of the middle board; align the two ends of the long side direction of the middle board with the two ends of the long side direction of the two side panels respectively; the thickness of all flame-retardant wood boards and flame-retardant unit inner boards used to splice the cabinet door panel is equal, and the thickness of the entire cabinet door panel is consistent during the assembly process; apply glue between each board in each splicing; perform pressure treatment on the assembled cabinet door panel in the splicing machine.

[0015] The fifth aspect provides a high-dimensional stability flame-retardant cabinet door panel, which is prepared by the above-described method.

[0016] According to this invention, moisture content variation is the primary factor affecting dimensional stability. Chemical modification of the long side panels creates a steric hindrance effect, which to some extent influences the moisture loss path. Simultaneously, modification with a silane coupling agent forms chemical functional groups with polarities close to that of moisture within the wood's micropores, mitigating the strong water adsorption effect of phosphorus-containing functional groups. Through weak polar forces within the multi-layered pore structure, the impact of moisture content adjustments during wood use on dimensional stability is reduced. Furthermore, optimization of the cabinet door panel construction further ensures dimensional stability. Attached Figure Description

[0017] Figure 1 This is a schematic diagram illustrating the structure of a cabinet door panel provided in one embodiment of the present invention. Detailed Implementation

[0018] Unless otherwise stated, the numerical range "A~B" includes the extreme values, and room temperature refers to 22~25℃.

[0019] To address the issue of flame retardant migration, the inventors chose to use a branched polyethyleneimine (PEI) aqueous solution as the flame retardant impregnation liquid to impregnate the wood boards and examine the dimensional stability of the boards.

[0020] The molecular formula of branched polyethyleneimine is as follows:

[0021]

[0022] The PEI aqueous solution was obtained by diluting commercially available branched PEI aqueous solution with a relative molecular weight of 800 and a concentration of 20wt% to 50wt%.

[0023] Example 1

[0024] With a density of 432 kg / m³ 3 A radiata pine board with a length of 3600 mm, a width of 100 mm, and a thickness of 17 mm was placed in a vacuum pressure impregnation tank. The tank was evacuated to a negative pressure of -0.1 MPa and maintained for 10 min. Then, under this negative pressure, a branched polyethyleneimine (PEI) aqueous solution with a molecular weight of 800 and a concentration of 0.56 mol / L (7 wt%) was injected into the impregnation tank until the entire radiata pine board was submerged. After that, the pressure was increased to 0.5 MPa and maintained for 1 h. The board was then removed and placed in a forced-air drying oven at 80 °C for 3 h. Finally, it was left to stand at room temperature for 24 h.

[0025] The following tests were conducted on Example 1 and the same raw material board without impregnation, and the results are shown in Table 1.

[0026] Vertical placement deformation (index 1): Maintain the test temperature and humidity at 25℃ and 50%. Insert the test sample 2cm deep into a vertical steel frame on either side and leave it for 720 hours. After removal, place it on a standard flat steel plate and measure the vertical distance between the sample and the steel plate at 80% of its length at both ends.

[0027] Deformation under horizontal placement (index 2): Maintain the test temperature and humidity at 25℃ and 50%, place the test sample horizontally on a standard flat steel plate, place it for 720 hours, and measure the vertical distance between the sample and the steel plate at 80% of the length at both ends.

[0028] Table 1:

[0029] According to Table 1, it can be seen that the deformation of the wood board impregnated with PEI impregnation solution is reduced. The selected branched PEI has a large number of amino cationic groups in its molecular chain, which can react with the hydroxyl groups on the wood fiber to form strong interionic bonds, thereby forming a cross-linking network on the fiber to a certain extent. The cross-linking network formed on the basis of the branched structure of branched PEI produces a steric hindrance effect in the multi-level pore structure of wood, which restricts the migration of free water to a certain extent. On the other hand, the addition of PEI reacts with the hydroxyl groups of wood, which plays a certain role in occupying the site and reducing the water absorption effect of the wood itself.

[0030] However, wood itself has a porous structure, so its impact on water migration is limited. The inventors further repeated the experiment of the above Example 1 at 25°C and 10% humidity (index 3) and 25°C and 80% humidity (index 4), and obtained the following comparative examples 3 and 4.

[0031] Deformation under vertical placement (index 3): Keep the test temperature and humidity at 25℃ and 10%, insert the test sample into the vertical steel frame with a depth of 2cm on any side, and place it for 720h. After removal, place it on a standard flat steel plate and measure the vertical distance between the sample and the steel plate at 80% of the length at both ends.

[0032] Vertical placement deformation (index 4): Keep the test temperature and humidity at 25℃ and 80%, insert the test sample into the vertical steel frame with a depth of 2cm on any side, and place it for 720h. After removing it, place it on a standard flat steel plate and measure the vertical distance between the sample and the steel plate at 80% of the length at both ends.

[0033] Table 2:

[0034]

[0035] To further mitigate the impact of moisture on wood dimensions, the inventors introduced phosphoric acid as another flame retardant.

[0036] Example 2

[0037] With a density of 432 kg / m³ 3 A radiata pine board with a length of 3600 mm, a width of 100 mm, and a thickness of 17 mm was placed in a vacuum pressure impregnation tank. The tank was evacuated to a negative pressure of -0.1 MPa and maintained for 10 min. Then, under this negative pressure, a branched polyethyleneimine (PEI) aqueous solution with a molecular weight of 800 and a concentration of 0.56 mol / L (7 wt%) was injected into the impregnation tank until the entire radiata pine board was submerged. After that, the pressure was increased to 0.5 MPa and maintained for 1 h. The board was then removed and placed in a forced-air drying oven at 80 °C for 3 h.

[0038] The dried solid wood boards were placed in another vacuum pressure impregnation tank, and the vacuum was drawn to a negative pressure of -0.1 MPa and maintained for 30 min. Then, under this negative pressure, a 20 mol / L phosphoric acid aqueous solution was injected into the impregnation tank until all the radiata pine solid wood boards were submerged. After that, the pressure was increased to 0.5 MPa and maintained for 5 h, and then the boards were taken out and placed in a forced-air drying oven to dry at 60 °C for 24 h.

[0039] The addition of phosphoric acid causes the unreacted amino groups on the polyethyleneimine grafted onto the wood to react with the hydroxyl groups on the phosphoric acid, thus improving steric hindrance to some extent. However, phosphoric acid has a strong hygroscopic effect, which weakens the contribution of PEI addition to dimensional stability to some extent. On the other hand, the introduction of phosphorus increases flame retardancy. Tests 1 and 2 were performed on the wood panels prepared in Example 2, and flame retardancy tests were also conducted on the wood panels prepared in Examples 1 and 2. The results are shown in Table 3.

[0040] Flame retardancy testing includes the following indicators:

[0041] Indicator 5: Peak heat release rate;

[0042] Indicator 6: Percentage reduction in peak heat release rate compared to ordinary radiata pine boards of the same thickness, as measured by cone calorimetry:

[0043] Indicator 7: Combustion rating.

[0044] Table 3:

[0045]

[0046] The inventors also investigated the phosphoric acid concentration in Example 2. At a low concentration (5 mol / L), the flame retardant properties and dimensional stability did not change significantly. When the concentration reached 12 mol / L, both flame retardant properties and dimensional stability began to improve. However, dimensional stability decreased after exceeding 35 mol / L, and the decrease was significant at 50 mol / L. This is likely due to an increase in unreacted phosphoric acid, leading to increased water absorption by the wood, and the free phosphoric acid accelerating moisture migration. Specific tests are shown in Table 4.

[0047] Table 4:

[0048]

[0049] To further examine the long-term durability of the dimensional stability of Example 2, the inventors extended the testing time for Indicators 1 and 2, namely Indicator 1A and Indicator 2A.

[0050] Vertical placement deformation (index 1A): Keep the test temperature and humidity at 25℃ and 50%, insert the test sample into the vertical steel frame with a depth of 2cm on either side and place it for 1440h. Then remove it and place it on a standard flat steel plate. Measure the vertical distance between the sample and the steel plate at 80% length at both ends.

[0051] Deformation under horizontal placement (index 2A): Maintain the test temperature and humidity at 25℃ and 50%, place the test sample horizontally on a standard flat steel plate, leave it for 1440 hours, and then measure the vertical distance between the sample and the steel plate at 80% of the length at both ends.

[0052] Table 5:

[0053]

[0054] According to Table 5, the decrease in dimensional stability significantly exceeded general estimates as the testing time increased. The inventors speculated that with prolonged time, the bond between PEI and phosphoric acid was more prone to breakage under the influence of free water in the wood. The phosphoric acid, detached from PEI, released more hydroxyl groups, leading to increased water absorption. The inventors further increased the humidity levels of indicators 1A and 2A and conducted further tests. The results were consistent with the inventors' speculation, as shown in Table 6.

[0055] Vertical placement deformation (index 1B): Maintain the test temperature and humidity at 25℃ and 50%. Insert the test sample 2cm deep into a vertical steel frame on either side and leave it for 720 hours. Then change the temperature and humidity conditions to 25℃ and 80% and continue for 360 hours. After removal, place it on a standard flat steel plate and measure the vertical distance between the sample and the steel plate at 80% of its length at both ends.

[0056] Vertical placement deformation (index 1C): Maintain the test temperature and humidity at 25℃ and 50%. Insert the test sample 2cm deep into a vertical steel frame on either side and leave it for 720 hours. Then change the temperature and humidity conditions to 25℃ and 90% and continue for 360 hours. After removal, place it on a standard flat steel plate and measure the vertical distance between the sample and the steel plate at 80% of its length at both ends.

[0057] Deformation under horizontal placement (index 2B): Keep the test temperature and humidity at 25℃ and 50%, place the test sample horizontally on a standard flat steel plate, and leave it for 720 hours. Then change the temperature and humidity conditions to 25℃ and 80% and continue for 360 hours. Measure the vertical distance between the sample and the steel plate at 80% of the length at both ends.

[0058] Deformation under horizontal placement (index 2C): Keep the test temperature and humidity at 25℃ and 50%, place the test sample horizontally on a standard flat steel plate, and leave it for 720 hours. Then change the temperature and humidity conditions to 25℃ and 90% and continue for 360 hours. Measure the vertical distance between the sample and the steel plate at 80% of the length at both ends.

[0059] Table 6:

[0060]

[0061] To overcome the loss of phosphoric acid, the inventors introduced another flame retardant, as described in Example 3.

[0062] Example 3

[0063] With a density of 432 kg / m³ 3 A radiata pine board with a length of 3600 mm, a width of 100 mm, and a thickness of 17 mm was placed in a vacuum pressure impregnation tank. The tank was evacuated to a negative pressure of -0.1 MPa and maintained for 10 min. Then, under this negative pressure, a branched polyethyleneimine (PEI) aqueous solution with a molecular weight of 800 and a concentration of 0.56 mol / L (7 wt%) was injected into the impregnation tank until the entire radiata pine board was submerged. After that, the pressure was increased to 0.5 MPa and maintained for 1 h. The board was then removed and placed in a forced-air drying oven at 80 °C for 3 h.

[0064] The dried solid wood boards were placed in another vacuum pressure impregnation tank, and the vacuum was drawn to a negative pressure of -0.1 MPa and maintained for 30 min. Then, under this negative pressure, a 20 mol / L phosphoric acid aqueous solution was injected into the impregnation tank until all the radiata pine solid wood boards were submerged. After that, the pressure was increased to 0.5 MPa and maintained for 5 h, and then the boards were taken out and placed in a forced-air drying oven to dry at 60 °C for 24 h.

[0065] The dried solid wood boards were placed in a vacuum pressurized impregnation tank, and a vacuum was drawn to a negative pressure of -0.1 MPa and maintained for 30 min. Then, under this negative pressure, a 30 mol / L aqueous solution of 3-aminopropyltriethoxysilane (a mixture of 3-aminopropyltriethoxysilane and water, wherein 3-aminopropyltriethoxysilane accounts for 30 mol / L of the solution) was injected into the impregnation tank until the entire radiata pine solid wood board was submerged. After that, the pressure was increased to 0.5 MPa and maintained for 5 h, and then the boards were removed and placed in a forced-air drying oven at 60 °C for 24 h.

[0066] The same tests as in Example 2 were performed, and the results are shown in Table 7.

[0067] Table 7:

[0068]

[0069]

[0070] According to Table 7, the introduction of 3-aminopropyltriethoxysilane makes the flame retardant system of wood board contain three flame retardant elements (NPSi), resulting in synergistic flame retardancy. Furthermore, 3-aminopropyltriethoxysilane eliminates the influence of the addition of flame retardant on dimensional stability through stronger steric hindrance and weaker water absorption.

[0071] In the above process, the typical reactions of the additives are as follows:

[0072] Reaction 1:

[0073]

[0074] Reaction 2:

[0075]

[0076] The inventors further considered that, for example, when the movement of moisture is completely restricted, a steric hindrance effect occurs. In this case, the complete inability of moisture to move is negative for the dimensional stability of the wood system. 3-Aminopropyltriethoxysilane, while acting as a steric hindrance agent, also functions as a coupling agent, promoting the movement of water molecules and balancing moisture migration. When humidity is too high, 3-aminopropyltriethoxysilane can, to some extent, hinder the rapid migration of moisture; when humidity is too low, it can promote the balance of wood moisture content. Therefore, the inventors tested indicators 3 and 4 in Example 3.

[0077] Table 8:

[0078]

[0079] According to Table 8, the changes in dimensional stability are negligible when the humidity is 10% and 80%.

[0080] The inventors further varied the waiting time to conduct tests on indicators 1A-C and 2A-C, and the results are shown in Table 9.

[0081] Table 9:

[0082]

[0083] According to Table 9, the dimensional stability did not change significantly when the testing time was extended. The inventors speculate that the molecular polarity of 3-aminopropyltriethoxysilane affected the bond separation of PEI and phosphoric acid.

[0084] To reduce the impact of unreacted phosphoric acid, the inventors increased the concentration of 3-aminopropyltriethoxysilane to capture more free phosphoric acid molecules, while ensuring that enough 3-aminopropyltriethoxysilane could reach the grafted phosphoric acid to form a long grafted chain. Size stability indices 1 and 2 were tested, and the results are shown in Table 10.

[0085] Table 10:

[0086]

[0087] According to Table 10, the improvement effect on size stability is not good when the concentration is low (20 mol), the improvement effect on size stability is satisfactory in the range of 30 to 70 mol / L, and the improvement effect on size stability tends to be gradual after reaching 70 mol / L.

[0088] The inventors realized that the method of the present invention is particularly suitable for use on long, upright wooden products, such as tall cabinet doors, but the present invention is not limited to this application and can also be applied to products used in a flat state, such as flooring.

[0089] On the other hand, in order to further improve the dimensional stability of the wooden board manufactured according to the present invention in the application of cabinet doors, the inventors have made structural modifications to the cabinet doors from the perspective of mechanical performance.

[0090] like Figure 1 As shown, the cabinet door 500 includes a middle panel 200 and side panels 101 and 102 located on both sides of the long side of the middle panel 200.

[0091] The intermediate board 200 is formed by splicing together multiple short boards 201 in both directions. Specifically, the leftmost side consists of three short boards 201 joined together along their long sides to form a first square board 211 in the horizontal direction. The next side consists of three short boards 201 joined together along their long sides to form a second square board 212 in the vertical direction. The first square board 211 and the second square board 211 are spliced ​​together with their short board splicing directions perpendicular to each other. This process is repeated to form the third to twelfth square boards, thus constituting the intermediate board 200. In this embodiment, the square boards are preferably square, but they can also be rectangular as long as a rectangular intermediate board can be formed.

[0092] The two long sides of the middle board 200 are spliced ​​to the side boards 101 and 102 along the board surface direction, respectively. The length of the middle board 200 is equal to the length of the side boards 101 and 102 and the two ends are aligned. In addition, it is preferable that all the flame-retardant wood boards and the inner boards of the unit used to splice the cabinet door panels have the same thickness, and the thickness of the entire cabinet door panel is made consistent during the splicing process.

[0093] In this invention, side panels 101 and 102 are impregnated with flame retardant to form flame retardant wood boards in accordance with the method of embodiment 3 of the present invention, and multiple short boards are impregnated in accordance with the method of embodiment 4 below.

[0094] Example 4

[0095] Multiple short boards of raw wood were placed in an impregnation tank, and a vacuum was drawn to a negative pressure of -0.1 MPa and maintained for 30 min. Under this negative pressure, a 50 mol / L aqueous solution of 3-aminopropyltriethoxysilane was injected into the impregnation tank until it at least covered the wood boards. The pressure was increased to 0.5 MPa and maintained for 5 h. Then the short boards were removed and placed in a drying oven and dried at 40 °C for 10 h.

[0096] The dried short board was placed in another impregnation tank, and a vacuum was drawn to a negative pressure of -0.1 MPa and maintained for 30 min. A 70 mol / L phosphoric acid aqueous solution was injected into the impregnation tank until it at least covered the wood board. The pressure was increased to 0.5 MPa and maintained for 2 h. Then the wood board was taken out and placed in a drying oven and dried at 40 °C for 10 h. The inner board of the unit was taken out and placed at room temperature for 10 h.

[0097] The short boards and side boards are spliced ​​together using the above splicing method, and adhesive (a two-component adhesive of polyvinyl acetate and isocyanate) is applied between the boards during splicing. The spliced ​​assembly is then placed in a splicing machine for pressure processing. Due to the composite splicing structure of the long boards and the intermediate boards of the longitudinal and transverse splicing panels, the stability of the cabinet door produced is further improved.

[0098] On the other hand, since the cabinet door is a relatively long product with a surface area much larger than its thickness, it is not suitable to apply flame-retardant layers in the thickness direction. Therefore, multi-element flame-retardant elements are introduced into the unit surface area to improve the flame-retardant efficiency according to the shape.

[0099] Example 5

[0100] Side panels: Radiata pine solid wood boards with a length of 3600mm, a width of 100mm, and a thickness of 17mm.

[0101] Short board: Radiata pine solid wood board with a length of 300mm, a width of 100mm, and a thickness of 17mm.

[0102] The side panels and short panels were treated with flame retardant according to Examples 3 and 5, respectively, and an adhesive (a two-component adhesive of polyvinyl acetate and isocyanate in a 1:1 mass ratio, with an adhesive application rate of 180 g / m) was applied between the panels. Figure 1 After the structural composite splicing is completed, the panels are spliced ​​by a high-frequency splicing machine to produce the cabinet door.

[0103] The performance test results for the cabinet doors are shown in Table 11.

[0104] Table 11:

[0105]

[0106] According to Table 11, the cabinet door prepared in Example 5 exhibits excellent flame retardant properties and further improved dimensional stability compared to Example 3. Furthermore, a ground impact test was conducted on the cabinet door prepared in this way, producing a "thud" sound, demonstrating that this structure eliminates the sound ghosting caused by the overlapping of internal wood structures, further proving its contribution to dimensional stability.

[0107] It should be noted that although different impregnation tanks are used for different steps in this embodiment, in practice, the same impregnation tank can generally be used for initial treatment and then reused for different steps. However, in summary, they can still be regarded as "first", "second", "third", "fourth" and "fifth" impregnation tanks.

Claims

1. A method for preparing a high-dimensional stability flame-retardant wood board, characterized in that, include: (1): Place the wood board in the first impregnation tank, evacuate to a negative pressure of -0.15 to -0.1 MPa and maintain for 10 to 20 minutes. Under this negative pressure, inject a branched polyethyleneimine aqueous solution with a molecular weight of 800 to 1000 and a concentration of 0.4 to 1.2 mol / L into the impregnation tank until it at least covers the wood board. Pressurize to 0.5 to 1.0 MPa and maintain for 1 to 2 hours. Then remove the wood board and place it in a drying oven and dry at 60 to 80°C for 3 to 4.5 hours to allow the amino groups on the branched polyethyleneimine to undergo a grafting reaction with the hydroxyl groups on the wood. (2): Place the dried wood board from (1) into the second impregnation tank, evacuate to a negative pressure of -0.15 to -0.1 MPa and maintain it for 20 to 30 minutes. Under this negative pressure, inject a 12 to 35 mol / L phosphoric acid aqueous solution into the impregnation tank until it at least covers the wood board. Pressurize to 0.5 to 1.0 MPa and maintain it for 5 to 6 hours. Then, remove the wood board and place it in a drying oven and dry it at 40 to 60°C for 20 to 24 hours to allow the unreacted amino groups on the branched polyethyleneimine grafted onto the wood to react chemically with the hydroxyl groups on the phosphoric acid. (3): Place the dried wood board from (2) into the third impregnation tank, evacuate to a negative pressure of -0.15 to -0.1 MPa and maintain for 30 to 40 minutes. Under this negative pressure, inject an aqueous solution of 30 to 70 mol / L of 3-aminopropyltriethoxysilane into the impregnation tank until it is at least submerged in the wood board. Pressurize to 0.5 to 1.0 MPa and maintain for 5 to 6 hours. Then take out the wood board and place it in a drying oven. Dry it at 40 to 60°C for 20 to 24 hours so that the unreacted hydroxyl groups on the phosphoric acid on the branched polyethyleneimine react with the amino groups on the 3-aminopropyltriethoxysilane. Take out the wood board and place it at room temperature for more than 10 hours. In the above process, the additives undergo the following reactions: 。 2. The preparation method according to claim 1, wherein, The concentration of the phosphoric acid aqueous solution injected into the impregnation tank in step (2) is 35 mol / L. The concentration of the 3-aminopropyltriethoxysilane aqueous solution injected into the impregnation tank in (3) is 70 mol / L.

3. A high-dimensional stability flame-retardant wood board, characterized in that, It is prepared by the preparation method described in claim 1 or 2.

4. The application of the flame-retardant wood board as described in claim 3 in the preparation of flooring or cabinet door panels.

5. A method for preparing a flame-retardant cabinet door panel with high dimensional stability, characterized in that, include: (4): Prepare two rectangular fire-retardant wood panels of the same predetermined size as described in claim 3 as side panels; (5): Prepare multiple rectangular wood panels of the same predetermined size as inner panels of a unit. Place the inner panels of the unit in the fourth impregnation tank, evacuate to a negative pressure of -0.15 to -0.1 MPa and maintain for 30 to 40 minutes. Under this negative pressure, inject a 50 to 70 mol / L aqueous solution of 3-aminopropyltriethoxysilane into the impregnation tank until it at least covers the wood panels. Pressurize to 0.5 to 1.0 MPa and maintain for 5 to 6 hours. Then remove the wood panels and place them in a drying oven to dry at 40 to 60°C for 20 to 24 hours. Place the wood board in the fifth impregnation tank, evacuate to a negative pressure of -0.15 to -0.1 MPa and maintain for 20 to 30 minutes. Pour a 50 to 70 mol / L phosphoric acid aqueous solution into the impregnation tank until it is at least submerged in the wood board. Pressurize to 0.5 to 1.0 MPa and maintain for 1 to 2 hours. Then remove the wood board and place it in a drying oven. Dry it at 40 to 60°C for 10 to 24 hours to allow the hydroxyl groups on the phosphoric acid to react chemically with the amino groups on 3-aminopropyltriethoxysilane. After drying, remove the inner board of the unit and place it at room temperature for more than 10 hours to obtain the flame-retardant inner board of the unit. (6): Take multiple flame-retardant inner panels obtained in (5) and sequentially splice them along the board surface direction in a way that the long sides are connected to form a square inner panel; the predetermined size of the flame-retardant inner panel ensures that a square inner panel can be spliced ​​by taking multiple flame-retardant inner panels and sequentially splicing them along the board surface direction in a way that the long sides are connected to form a square inner panel; splice multiple square inner panels and sequentially splice them along the board surface direction to form a rectangular middle panel, wherein the splicing direction of the flame-retardant inner panels of each two adjacent square inner panels is perpendicular to each other; along the two long sides of the middle panel... The side panels prepared in step (4) are spliced ​​together along their long sides to form a cabinet door panel. The predetermined size of the flame-retardant wood board ensures that its long side is equal to the long side of the middle board. The two ends of the long side of the middle board are aligned with the two ends of the long side of the two side panels. All flame-retardant wood boards and flame-retardant unit inner boards used to splice the cabinet door panel have the same thickness, and the thickness of the entire cabinet door panel is consistent during the splicing process. Glue is applied between the boards in each splicing process. The assembled cabinet door panel is pressure treated in a splicing machine.

6. A high-dimensional stability flame-retardant cabinet door panel, characterized in that, It is prepared by the method described in claim 5.

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