A color-changing flame-retardant wood composite material and its preparation method

Abstract

The present invention discloses a preparation method of a color-changing flame-retardant wood composite material, which includes first weighing cetyltrimethylammonium bromide and calcium chloride, dissolving them in water and stirring until the solution is clear, then adding acrylamide and potassium persulfate and stirring to make them fully mixed, subsequently adding methyl blue and tetramethylethylenediamine to obtain a mixed solution, pouring the mixed solution into a petri dish containing wood for soaking, then taking out the wood and putting it into a vacuum drying oven for aging treatment, and finally obtaining the color-changing flame-retardant wood composite material. Using the method of the present invention to prepare the color-changing flame-retardant wood composite material not only has a significant color change after encountering high temperature to achieve the function of flame-retardant warning, but also has excellent flame-retardant performance.

Description

Technical Field

[0001] The present invention relates to the field of composite materials, and particularly to a color-changing flame-retardant wood composite material and a preparation method thereof. Background Art

[0002] Wood is a natural organic composite material, which is rich in sources, renewable and structurally layered, and is widely used as a renewable building material for homes and outdoor structures. However, its flammability is the main problem hindering its wide application. The combustion of general wood can be roughly divided into four processes: the first is the wood drying process below 150°C; the second is the pre-carbonization stage at 150 - 270°C; the third is the carbonization stage at 270 - 400°C; and the fourth is the combustion spread stage at 400 - 500°C. At present, wood flame-retardant treatment is an important means to improve the fire safety performance of wood-based materials and is also a basic requirement in the application fields of existing building wood, household wood, etc.

[0003] At present, traditional flame retardants such as halogen-based, boron-based or silicon-based compounds are generally added to wood to improve its flame retardant performance. However, halogen-based flame retardants will produce a large amount of harmful gases, which will pollute the environment and damage human health, and have been prohibited from use. In addition, for example, Chinese Patent CN202011114340.9 discloses a flame-retardant wood composite material and a preparation method thereof. An organosilicon boron flame retardant is added to a polyethylene glycol solution and a urea solution and uniformly mixed, and the pH value is adjusted with ammonia water to obtain a modified solution; the wood is placed in a pressure impregnation tank and evacuated; the modified solution is added to the pressure impregnation tank for vacuum impregnation; after the modified solution is removed, it is kept at a high temperature and high pressure for a period of time, and then cooled to room temperature, washed and dried to obtain the flame-retardant wood composite material. However, flame retardants such as boron-based or silicon-based have low toxicity and low cost but are prone to precipitation, affecting the final flame retardant effect of the wood. Therefore, it is necessary to develop a new type of color-changing flame-retardant wood composite material and a preparation method thereof. Summary of the Invention

[0004] In view of this, the present invention provides a new type of color-changing flame-retardant wood composite material to solve the problem of poor flame retardant performance of wood existing in the prior art.

[0005] On the one hand, the present invention provides a preparation method of a color-changing flame-retardant wood composite material. First, cetyltrimethylammonium bromide and calcium chloride are weighed and dissolved in water and stirred until the solution is clear. Then acrylamide and potassium persulfate are added and stirred to make them fully mixed. Subsequently, methylene blue and tetramethylethylenediamine are added to obtain a mixed solution. The mixed solution is poured into a petri dish containing wood for soaking, and then the wood is taken out and placed in a vacuum drying oven for aging treatment, and finally a color-changing flame-retardant wood composite material is obtained.

[0006] Preferably, the dosage of cetyltrimethylammonium bromide is 0.5 g, and the dosage of calcium chloride is 5 g.

[0007] Preferably, the dosage of methylene blue is 0.015 g and that of tetramethylethylenediamine is 0.52 mL.

[0008] Preferably, the dosage of acrylamide is 5 g and that of potassium persulfate is 0.04 g.

[0009] Preferably, the wood is basswood board or balsa wood.

[0010] Preferably, the aging temperature is 65 °C and the aging time is 12 h.

[0011] By using the preparation method of a novel color-changing flame-retardant wood composite material provided by the present invention, the process is simple, the cost is low, and it is easy to be popularized and applied industrially. Moreover, the composite material prepared by this method has strong adhesion and no falling-off phenomenon. By using calcium chloride and polyacrylamide, a polymer hydrogel with a large number of spatial networks and hydrophilic groups is formed, so that the bound water or free water groups are fixed around the polymer chains. When heated, most of the heat can be absorbed, and at the same time, oxygen is diluted and isolated, thus playing an excellent flame-retardant performance. Moreover, by using the synergistic effect among calcium chloride, cetyltrimethylammonium bromide and methylene blue, it changes color significantly when encountering high temperature, and can play a role in flame-retardant warning. Description of the Drawings

[0012] Figure 1 Photographs of basswood board before combustion, at 28 s of combustion and at 45 s of combustion;

[0013] Figure 2 Photographs of the color-changing flame-retardant wood composite material of Example 1 before combustion, at 28 s of combustion, at 105 s of combustion and at 240 s of combustion;

[0014] Figure 3 Photographs of balsa wood before combustion, at 20 s of combustion and at 200 s of combustion;

[0015] Figure 4 Photographs of the color-changing flame-retardant wood composite material of Example 2 before combustion, at 20 s of combustion and at 200 s of combustion;

[0016] Figure 5 Thermogravimetric test chart of balsa wood;

[0017] Figure 6 Thermogravimetric test chart of the color-changing flame-retardant balsa wood composite material of Example 2;

[0018] Figure 7 Cone calorimeter test charts of balsa wood and the color-changing flame-retardant balsa wood composite material of Example 2, where 7a represents the heat release rate curve; 7b represents the smoke release rate curve; 7c represents the carbon dioxide release rate (CO2P) curve; 7c represents the carbon monoxide release rate curve. Detailed Embodiments

[0019] The principles and features of the present invention will be described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not intended to limit the scope of the present invention.

[0020] Example 1: A method for preparing a novel color-changing flame-retardant wood composite material includes the following steps: Weigh 0.5 g of cetyltrimethylammonium bromide (CTAB) and 5 g of calcium chloride, dissolve them in 30 mL of deionized water, and stir until the solution is clear. Then weigh 5 g of acrylamide and 0.04 g of potassium persulfate, add them to a beaker, and stir for 1 h to fully mix them. Subsequently, add 0.015 g of methylene blue and 0.52 mL of tetramethylethylenediamine to obtain a mixed solution. Quickly pour the mixed solution into a petri dish containing basswood boards (2 mm x 5 cm x 10 cm), soak the basswood boards completely in the solution for 5 min, and then take out the wood and place it in a vacuum drying oven for aging at 65 °C for 12 h to obtain the color-changing flame-retardant wood composite material.

[0021] Example 2: Weigh 0.5 g of cetyltrimethylammonium bromide and 5 g of calcium chloride, dissolve them in 30 mL of deionized water, and stir until the solution is clear. Then weigh 5 g of hydrophilic monomer acrylamide and 0.04 g of initiator potassium persulfate, add them to a beaker, and stir for 1 h to fully mix them. Subsequently, add 0.015 g of methylene blue and 0.52 mL of tetramethylethylenediamine to obtain a mixed solution. Quickly pour the mixed solution into the bottom of a petri dish containing balsa wood, soak the balsa wood (1 cm x 1 cm x 10 cm, density 0.16 - 0.2 g / cm -3 ) completely in the solution for 5 min, then take out the balsa wood and place it in a vacuum drying oven for aging at 65 °C for 12 h to obtain the color-changing flame-retardant wood composite material.

[0022] Comparative Example 1: The difference between Comparative Example 1 and Example 2 is that 0.5 g of cetyltrimethylammonium bromide (CTAB) is not added, and only methylene blue - calcium chloride - polyacrylamide is used to perform composite treatment on the balsa wood board to obtain the wood composite material.

[0023] Comparative Example 2: The difference between Comparative Example 2 and Example 2 is that 0.015 g of methylene blue is not added, and only cetyltrimethylammonium bromide - calcium chloride - polyacrylamide is used to perform composite treatment on the balsa wood board to obtain the wood composite material.

[0024] Comparative Example 3: The difference between Comparative Example 3 and Example 2 is that 5 g of calcium chloride is not added, and only cetyltrimethylammonium bromide - methylene blue - polyacrylamide is used to perform composite treatment on the balsa wood board to obtain the wood composite material.

[0025] Comparative Example 4: The difference between Comparative Example 5 and Example 2 is that this example is an untreated balsa wood board.

[0026] (1) Combustion tests were respectively carried out on the wood composites prepared in Example 2 and Comparative Examples 1 to 3. As shown in the results of Table 1, the wood composite prepared in Example 2 was the natural color of the log. After high-temperature combustion treatment, the wood composite changed from the natural color to blue, and continued high-temperature treatment changed it to black. However, the wood composites prepared in Comparative Examples 1 to 3 did not show any color change during the high-temperature treatment process, indicating that the color change phenomenon of this material was caused by the synergistic effect of cetyltrimethylammonium bromide, calcium chloride and methyl blue, providing a warning signal for flame retardancy. Compared with Comparative Example 3 and Comparative Example 4, under the synergistic effect of the reaction components of calcium chloride and polyacrylamide added in Example 2, the heat release rate of the prepared wood composite was much lower than that of other original woods, and there was no falling-off phenomenon, and the flame retardant performance was significantly improved.

[0027] Table 1 Effects of different reaction components on the properties of wood composites

[0028]

[0029] (2) As Figure 1 and Figure 2 the results show, combustion tests were respectively carried out on the basswood board and the color-changing flame-retardant wood composite of Example 1. It can be seen that the wood texture in the basswood board and the color-changing flame-retardant wood composite was still clear before combustion, indicating that the appearance of the wood was not affected after composite treatment by the method of the present invention; in addition, when the basswood board burned for 28 s, the flame spread to the whole piece of wood, and when it burned for 45 s, the basswood board had completely burned; while there was no flame generated in the color-changing flame-retardant wood composite, and when it reached 105 s, it was observed that the wood changed from its original color to blue; when it burned for 240 s, the hydrogel on the outer layer of the color-changing flame-retardant wood composite burned and turned black. It shows that the flame retardant performance of the basswood treated by the method of the present invention has been greatly improved.

[0030] (3) As Figure 3 and Figure 4 the results show, combustion tests were respectively carried out on balsa wood and the color-changing flame-retardant wood composite of Example 2. When the balsa wood burned for 20 s, it burned and turned black, and when it burned for 200 s, the lower end of the balsa wood had begun to completely burn into ashes, while the color-changing flame-retardant wood composite of Example 2 also began to turn blue due to high temperature; the hydrogel on the outer layer of the color-changing flame-retardant wood composite burned and turned black but the wood inside remained intact, indicating that the flame retardant performance of the balsa wood treated by the method of the present invention has been greatly improved.

[0031] (4) Thermogravimetric tests were carried out on the balsa wood and the color-changing flame-retardant balsa wood composite of Example 2. The results are as Figure 5 and Figure 6As shown, the color-changing flame-retardant balsa wood composite material of Example 2 has two peaks at 111.6°C and 143.4°C with an area of 825.9 J / g, while balsa wood has only a relatively smooth peak at 346.6°C with an area of 64.32 J / g, indicating that the composite material can absorb heat during combustion, delay the spread of combustion, and have good flame retardant properties.

[0032] (5) Cone calorimeter test was performed on balsa wood and the color-changing flame-retardant balsa wood composite material of Example 2. Figure 7 The results of a show that the peak heat release rate (HRR) of balsa wood is 212kw / m 2 The peak heat release rate of the color-changing flame-retardant balsa wood composite material is 25kw / m 2 , indicating that the composite material greatly delays the release of heat during combustion; Figure 7 The results of b show that the smoke release rate (SPR) of the color-changing flame-retardant balsa wood composite material is lower than that of balsa wood and mainly occurs in the late stage of combustion; Figure 7 The results of c and 7d show that the carbon dioxide release rate (CO2P) and carbon monoxide release rate (COP) are much lower than those of balsa wood and mainly occur in the later stage of combustion.

[0033] In summary, the color-changing flame-retardant wood composite material prepared by this method takes longer to start burning at high temperature, and the flame retardant performance is greatly improved; and the color of the composite material changes from the color of the wood itself to blue at high temperature, and the significant color change after encountering high temperature can play a flame retardant warning role.

[0034] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A preparation method of a color-changing flame-retardant wood composite material, characterized in that It includes the following method: First, weigh cetyltrimethylammonium bromide and calcium chloride, dissolve them in water, and stir until the solution is clear. Then, add acrylamide and potassium persulfate and stir to make them fully mixed. Subsequently, add methylene blue and tetramethylethylenediamine to obtain a mixed solution. Pour the mixed solution into a petri dish containing wood for soaking, and then take out the wood and put it into a vacuum drying oven for aging treatment to finally obtain a color-changing flame-retardant wood composite material; the dosage of cetyltrimethylammonium bromide is 0.5 g, and the dosage of calcium chloride is 5 g; the dosage of methylene blue is 0.015 g, and the tetramethylethylenediamine is 0.52 mL; the acrylamide is 5 g, and the potassium persulfate is 0.04 g; the aging temperature is 65 °C, and the aging time is 12 h.

2. The preparation method of a color-changing flame-retardant wood composite material according to claim 1, characterized in that, The wood is basswood board or balsa wood.

3. A color-changing flame-retardant wood composite material prepared by the method according to any one of claims 1 or 2.

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