Flame-retardant modified wood, preparation method and application

Abstract

The invention belongs to the technical field of flame-retardant wood preparation, and relates to flame-retardant modified wood and a preparation method and application thereof.The preparation method comprises the following steps that wood is soaked in alkali liquor, washed and dried, then residual alkali liquor is removed, drying is conducted, and delignification wood is obtained; the delignification wood is placed in an aqueous solution containing aluminum sulfate octadecahydrate and urea, the reaction temperature is controlled to be 200-250 DEG C, the reaction pressure is controlled to be 3-10 MPa, drying is conducted after reaction, the delignification wood with the surface modified by pseudo-boehmite is obtained, and the mass ratio of the aluminum sulfate octadecahydrate to the urea is (3-5): 1; the delignification wood subjected to surface modification of the pseudo-boehmite is soaked in an ammoniated phytic acid solution, taken out and dried, and flame-retardant modified wood is obtained; the preparation method of the ammoniated phytic acid solution comprises the following steps: mixing phytic acid and urea, and reacting at 90-120 DEG C to obtain the ammoniated phytic acid solution; the molar ratio of phytic acid to urea is 1: (3-5); the flame retardant effect of the wood is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of flame-retardant wood preparation, and particularly relates to a flame-retardant modified wood, a preparation method and an application thereof. Background Art

[0002] With the rapid development of materials such as bamboo and wood, they have been widely used in fields such as construction and home furnishing. However, wood is a flammable material, and once it burns, a large amount of heat will be released in a short time. Therefore, the flame-retardant performance of the above materials is crucial for the application of wood.

[0003] Currently, mainly by using the soaking or spraying process to modify the wood surface to obtain flame-retardant wood, but the flame-retardant performance of the wood obtained by this method is limited, which restricts its wider application. At the same time, there are also problems such as the short retention time of the flame-retardant liquid on the wood surface.

[0004] Patent application publication number CN 119159655 A discloses an in-situ impregnation method for flame-retardant treatment of wood, including the following steps: preparation of an aqueous carbon source solution; preparation of a three-source integrated flame retardant; preparation of a metal salt solution; preparation of a flame retardant solution; preparation of flame-retardant modified wood: placing the wood in the metal salt solution and performing the first vacuum negative pressure impregnation, and drying until the moisture content of the wood is 20% - 50% to obtain a semi-finished product I of flame-retardant modified wood; placing the semi-finished product I of flame-retardant modified wood in the flame retardant solution and performing the second vacuum negative pressure impregnation to obtain a semi-finished product II of flame-retardant modified wood; drying the semi-finished product II of flame-retardant modified wood to obtain a finished product of flame-retardant modified wood, that is, a modified wood composite material. It loads the carbon source, flame retardant and metal salt on the wood through two-step vacuum negative pressure impregnation, and the flame-retardant effect still needs to be further improved. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a flame-retardant modified wood, a preparation method and an application thereof to improve the flame-retardant effect of wood.

[0006] An embodiment of the present invention provides a preparation method for a flame-retardant modified wood, including the following steps: Soak the wood in an alkali solution, wash and dry it, then remove the remaining alkali solution and bake it to obtain delignified wood; Place the delignified wood in an aqueous solution containing aluminum sulfate octadecahydrate and urea, control the reaction temperature at 200 - 250 °C, the reaction pressure at 3 - 10 MPa, and bake it after the reaction to obtain delignified wood surface-modified with boehmite, and the mass ratio of the aluminum sulfate octadecahydrate to urea is 3 - 5:1; Immerse the delignified wood surface-modified with boehmite in an ammoniated phytic acid solution, take it out and bake it to obtain a flame-retardant modified wood; The preparation method of the ammoniated phytic acid solution is to mix phytic acid and urea and react at 90-120°C to obtain the ammoniated phytic acid solution; the molar ratio of phytic acid to urea is 1:3-5.

[0007] Preferably, the alkali solution is sodium hydroxide or potassium hydroxide solution with a weight concentration of 1-2%, and the soaking time is 0.5-1 h.

[0008] Preferably, the method for removing the residual alkali solution is to soak the dried wood in deionized water, and replace the deionized water at least every 1 h during the soaking process until the solution is neutral.

[0009] Preferably, in the preparation step of the pseudo-boehmite surface-modified delignified wood, the mass ratio of aluminum sulfate octadecahydrate to urea is 4:1, the reaction temperature is 240°C, the reaction pressure is 3 MPa, and the reaction time is 5-10 h.

[0010] Preferably, the mass concentration of the phytic acid is 60-80%.

[0011] Preferably, the time for immersing the pseudo-boehmite surface-modified delignified wood in the ammoniated phytic acid solution is 10-30 min.

[0012] Preferably, in the preparation method of the ammoniated phytic acid solution, the molar ratio of phytic acid to urea is 1:4, the reaction temperature is 90°C, and the reaction time is 1 h.

[0013] Preferably, in the preparation method of the ammoniated phytic acid solution, the reaction time is 1 h.

[0014] An embodiment of the present invention provides a flame-retardant modified wood prepared by using the described preparation method.

[0015] An embodiment of the present invention provides an application of the described flame-retardant modified wood, and the flame-retardant modified wood is used for building or household materials.

[0016] The beneficial effect of the present invention is that the present invention uses an alkali solution to remove its lignin to obtain delignified wood with a larger specific surface area, uses the coprecipitation method to load pseudo-boehmite on the wood interface to endow the wood with negative charges, and finally uses positively charged ammoniated phytic acid to further modify it through ionic bond reaction to obtain long-lasting and highly flame-retardant wood.

[0017] The present invention reduces the concentration of the lye, controls the mass ratio of aluminum sulfate octadecahydrate to urea to be 3-5:1, the reaction temperature to be 200-250 °C, and the reaction pressure to be 3-10 MPa. Experiments have found that during the combustion process, pseudo-boehmite can release water vapor through thermal degradation to reduce the surface temperature of the wood and dilute the air concentration. At the same time, the generated alumina can be used to cover the wood surface, and together with the degradation products of phytic acid after ammoniation, high-quality char residues can be obtained to achieve a barrier effect. Therefore, it can significantly increase the ignition time and peak time of the wood, reduce the peak value of the heat release of the wood, and effectively improve the flame retardancy of the wood. Description of the Drawings

[0018] Figure 1 It is a graph showing the change of the heat release rate of wood and its modified wood over time.

[0019] Figure 2 It is the microscopic structure of the pseudo-boehmite prepared in Example 1 of the present invention.

[0020] Figure 3 It is the infrared spectrum of the pseudo-boehmite prepared in Example 1 of the present invention.

[0021] Figure 4 It is the infrared spectrum of the ammoniated phytic acid prepared in Example 1 of the present invention. Detailed Description of the Invention

[0022] The present invention will be further described below in conjunction with embodiments to facilitate understanding of the technical solution of the present invention, but it should not be understood that the scope of the present invention is limited to the following embodiments.

[0023] Example 1 A method for preparing flame-retardant modified wood includes the following steps: (1) First, soak the log in a 1% (weight concentration) NaOH solution for 30 minutes. After washing and drying, soak it in deionized water for 24 hours. Replace the deionized water every 2 hours during the soaking period to further remove the residual NaOH solution until the pH value of the solution is 7, and then dry it to obtain delignified wood; (2) Take the delignified wood block and place it in an aqueous solution containing a certain amount of aluminum sulfate octadecahydrate and urea, and then introduce them into a hydrothermal autoclave together to carry out a reaction at a certain temperature and pressure. Then take it out and dry it to obtain delignified wood modified with pseudo-boehmite; the mass ratio of aluminum sulfate octadecahydrate to urea is 3:1; The microscopic structure of the pseudo-boehmite is as Figure 2 shown, which is a petal-like structure; the infrared spectrum is as Figure 3 shown, and 3400 and 3100 cm -1 are the -OH characteristic peaks of the pseudo-boehmite, and 604 cm-1 are the Al-O characteristic peaks of pseudo-boehmite, 1072 and 738 cm -1 are the Al(OH) characteristic peaks of pseudo-boehmite.

[0024] For the reaction in the autoclave, the reaction temperature is 240 °C, the reaction pressure is 3 MPa, and the reaction time is 6 hours.

[0025] (3) Add appropriate ratios of 70% phytic acid (weight concentration) and urea to a suitable three-necked flask. Heat and stir the solution under certain temperature conditions to obtain an ammoniated phytic acid solution as a light brown liquid. The molar ratio of phytic acid to urea is 1:4; The reaction temperature in the ammoniation of phytic acid is 90 °C, and the reaction time is 1 hour.

[0026] The infrared spectrum of ammoniated phytic acid is as Figure 4 shown. Under certain conditions, PA (phytic acid) and Urea (urea) are used to obtain a PA-Urea complex (the physical picture is also embedded in it, which is a light yellow liquid), and its infrared spectrum is as Figure 4 shown: In the product PA-Urea, 1097 and 938 cm -1 are the P-O and P-O-C characteristic peaks respectively, showing a red shift relative to PA. At 1662 and 1626 cm -1 the N-H characteristic peak from Urea is found, and at the same time, at 1400 cm -1 the NH4 + cm -1 characteristic peak appears, and the C=O bond of Urea (1680 cm -1 ) does not appear in PA-Urea, indicating that PA-Urea can be successfully synthesized.

[0027] (4) Immerse the delignified wood surface-modified with pseudo-boehmite in the ammoniated phytic acid solution for 3 min, take it out and dry it to obtain the flame-retardant modified wood.

[0028] Flame retardancy test: It is measured by a cone calorimeter according to the ISO 5660 test method.

[0029] Through experimental tests, the performance results are as Figure 1 (cone calorimeter heat release value) and Table 1 (cone calorimeter heat release value and related key data) shown.

[0030] Example 2 A preparation method of flame-retardant modified wood, comprising the following steps: (1) First, soak the log in a 1% (weight concentration) NaOH solution for 30 minutes. After washing and drying, soak it in deionized water for 24 hours. Replace the deionized water every 2 hours during the soaking period to further remove the residual NaOH solution until the pH value of the solution is 7, and then dry it to obtain delignified wood; (2) Take the delignified wood block and place it in an aqueous solution containing a certain amount of aluminum sulfate octadecahydrate and urea, and then introduce them together into a hydrothermal autoclave to react at a certain temperature and pressure. Then take it out and dry it to obtain delignified wood surface-modified with boehmite; the mass ratio of aluminum sulfate octadecahydrate to urea is 4:1; For the reaction in the hydrothermal autoclave, the reaction temperature is 240 °C, the reaction pressure is 3 MPa, and the reaction time is 6 hours.

[0031] (3) Add an appropriate ratio of 70% phytic acid (weight concentration) and urea to a suitable three-necked flask. Heat and stir the solution under certain temperature conditions to obtain an ammoniated phytic acid solution with a light brown liquid. The molar ratio of phytic acid to urea is 1:4; The reaction temperature in the ammoniation of phytic acid is 90 °C, and the reaction time is 1 hour.

[0032] (4) Immerse the delignified wood surface-modified with boehmite in the ammoniated phytic acid solution for 3 min, take it out and dry it to obtain flame-retardant modified wood.

[0033] Flame retardancy test: It is determined by a cone calorimeter according to the ISO 5660 test method.

[0034] Through experimental tests, the performance results are shown in Figure 1 (cone calorimeter heat release value) and Table 1 (cone calorimeter heat release value and related key data).

[0035] Example 3 A preparation method of flame-retardant modified wood, comprising the following steps: (1) First, soak the log in a 1% (weight concentration) NaOH solution for 30 minutes. After washing and drying, soak it in deionized water for 24 hours. Replace the deionized water every 2 hours during the soaking period to further remove the residual NaOH solution until the pH value of the solution is 7, and then dry it to obtain delignified wood; (2) Take the delignified wood block and place it in an aqueous solution containing a certain amount of aluminum sulfate octadecahydrate and urea, and then introduce them together into a hydrothermal autoclave to react at a certain temperature and pressure. Then take it out and dry it to obtain delignified wood surface-modified with boehmite; the mass ratio of aluminum sulfate octadecahydrate to urea is 5:1; For the reaction in the hydrothermal autoclave, the reaction temperature is 240 °C, the reaction pressure is 3 MPa, and the reaction time is 6 hours.

[0036] (3) Add 70% phytic acid (weight concentration) and urea in an appropriate ratio to a suitable three-necked flask. Heat and stir the solution under certain temperature conditions to obtain an ammoniated phytic acid solution in light brown liquid. The molar ratio of phytic acid to urea is 1:4; The reaction temperature in the ammoniation of phytic acid is 90 °C, and the reaction time is 1 hour.

[0037] (4) Place the delignified wood with surface-modified pseudoboehmite in the ammoniated phytic acid solution for 3 minutes, take it out, and dry it to obtain flame-retardant modified wood.

[0038] Flame retardancy test: Determine by means of a cone calorimeter according to the ISO 5660 test method.

[0039] Through experimental tests, the performance results are as Figure 1 shown in (cone calorimeter heat release value) and Table 1 (cone calorimeter heat release value and related key data).

[0040] Table 1 Heat release rate and related core data of wood and its modified wood

[0041] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that the weight concentration of the sodium hydroxide solution in step (1) is 4%. Others are the same as in Example 1.

[0042] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that the mass ratio of aluminum sulfate octadecahydrate to urea in step (2) is 2.5:1. Others are the same as in Example 1.

[0043] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that the mass ratio of aluminum sulfate octadecahydrate to urea in step (2) is 6:1. Others are the same as in Example 1.

[0044] Comparative Example 4 The difference between Comparative Example 4 and Example 1 is that the reaction temperature in step (2) is 190 °C, the reaction pressure is 1 MPa, and the reaction time is 6 hours. Others are the same as in Example 1.

[0045] Through experimental tests, the performance results are shown in Table 2 (cone calorimeter heat release value and related key data).

[0046] Table 2 Heat release rate and related core data of wood and its modified wood

[0047] As can be seen from Table 1-2, the flame retardant effect obtained by treating wood with high-concentration alkali solution (Comparative Example 1) is worse than that of Example 1; if the mass ratio of aluminum sulfate octadecahydrate and urea is changed, it can affect the flame retardant performance of wood. The main reason is that the ratio of the two is different (Comparative Example 2 and Comparative Example 3), which affects the structure and morphology of the product, and thus affects the final performance; the reaction conditions are also crucial for the formation of the product (Comparative Example 4), seriously affecting the complete morphology and crystal structure of the obtained product, as well as the purity of the product. Therefore, it can also affect the flame retardant performance of wood.

[0048] Those of ordinary skill in the art should understand that the discussion of any above embodiment is only exemplary and is not intended to imply that the scope of protection of this application is limited to these examples; under the concept of this application, the technical features in the above embodiments or different embodiments can also be combined, and the steps can be implemented in any order, and there are many other variations in different aspects of one or more embodiments in this application as described above. For the sake of brevity, they are not provided in detail.

[0049] One or more embodiments of this application are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of this application. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of one or more embodiments of this application shall be included within the scope of protection of this application.

Claims

1. A preparation method of flame-retardant modified wood, characterized in that, It includes the following steps: Soak the wood in an alkali solution, wash and dry it, then remove the residual alkali solution and dry it to obtain delignified wood; Place the delignified wood in an aqueous solution containing aluminum sulfate octadecahydrate and urea, control the reaction temperature at 200 - 250 °C and the reaction pressure at 3 - 10 MPa, and dry it after the reaction to obtain delignified wood surface-modified with boehmite, where the mass ratio of aluminum sulfate octadecahydrate to urea is 3 - 5:1; Immerse the delignified wood surface-modified with boehmite in an ammoniated phytic acid solution, take it out and dry it to obtain flame-retardant modified wood; The preparation method of the ammoniated phytic acid solution is to mix phytic acid and urea and react at 90 - 120 °C to obtain the ammoniated phytic acid solution; the molar ratio of phytic acid to urea is 1:3 - 5.

2. The preparation method according to claim 1, characterized in that, The alkali solution is a sodium hydroxide or potassium hydroxide solution with a weight concentration of 1 - 2%, and the soaking time is 0.5 - 1 h.

3. The preparation method according to claim 1, characterized in that, The method for removing the residual alkali solution is to soak the dried wood in deionized water and change the deionized water at least every 1 h during the soaking process until the solution is neutral.

4. The preparation method according to claim 1, characterized in that, In the preparation step of the delignified wood surface-modified with boehmite, the mass ratio of aluminum sulfate octadecahydrate to urea is 4:1, the reaction temperature is 240 °C, the reaction pressure is 3 MPa, and the reaction time is 5 - 10 h.

5. The preparation method according to claim 1, characterized in that, The mass concentration of the phytic acid is 60 - 80%.

6. The preparation method according to claim 1, characterized in that, The time for immersing the delignified wood surface-modified with boehmite in the ammoniated phytic acid solution is 10 - 30 min.

7. The preparation method according to claim 1, characterized in that, In the preparation method of the ammoniated phytic acid solution, the molar ratio of phytic acid to urea is 1:4, the reaction temperature is 90 °C, and the reaction time is 1 h.

8. The preparation method according to claim 1, characterized in that, In the preparation method of the ammoniated phytic acid solution, the reaction time is 1 h.

9. A flame-retardant modified wood, characterized in that, It is prepared by using the preparation method according to any one of claims 1 - 8.

10. Use of a flame-retardant modified wood as described in claim 9, characterized in that, The flame-retardant modified wood is used for building or household materials.

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