Method for preparing double flame-retardant wood

Abstract

The application discloses a preparation method of double-interior-and-exterior flame-retardant wood, which comprises the following steps: drying raw wood to obtain primary dried wood; sequentially immersing, freezing, thawing and drying the primary dried wood by deionized water to obtain secondary dried wood; immersing the secondary dried wood in an impregnation solution and drying the immersed wood to obtain tertiary dried wood, wherein the impregnation solution is a solution formed by dissolving a flame retardant in deionized water, and the flame retardant is configured by ammonium polyphosphate and borax; coating a coating solution on the surface of the tertiary dried wood and drying the wood to obtain double-interior-and-exterior flame-retardant wood, wherein the coating solution is a melamine coating solution. The preparation method of the double-interior-and-exterior flame-retardant wood can obtain flame-retardant wood with high fire resistance by synergistically treating raw wood with double-interior-and-exterior flame retardants.

Description

Technical Field

[0001] This invention belongs to the field of wood modification and treatment technology, and specifically provides a method for preparing wood with both internal and external flame retardancy. Background Technology

[0002] Wood is a renewable and environmentally friendly material, widely used in building materials, furniture, and interior decoration due to its low price and ease of processing. However, wood is mainly composed of cellulose, hemicellulose, and lignin, with C, H, and O as its main constituent elements. Wood is flammable, has poor fire resistance, and is highly susceptible to fire when exposed to fire or high temperatures.

[0003] Therefore, how to modify wood to be flame-retardant in order to improve its fire resistance has become an urgent problem to be solved. Summary of the Invention

[0004] Therefore, the purpose of this invention is to provide a method for preparing double-layered flame-retardant wood to solve the problem of poor fire resistance of wood.

[0005] This invention provides a method for preparing fire-retardant wood with both internal and external retardancy, comprising the following steps:

[0006] Step 1: Dry the logs to obtain primary dried wood;

[0007] Step 2: The primary dried wood is sequentially soaked in deionized water, frozen, thawed, and dried to obtain secondary dried wood;

[0008] Step 3: Immerse the secondary dried wood in the impregnation solution and then dry the impregnated wood to obtain tertiary dried wood. The impregnation solution is a solution in which a flame retardant is dissolved in deionized water. The flame retardant is prepared by ammonium polyphosphate and borax in a mass ratio of 1 to 2.5:1. The flame retardant accounts for 5 to 12% of the mass of the impregnation solution.

[0009] Step 4: Apply the coating liquid to the surface of the three-time dried wood and dry it to obtain double flame-retardant wood, wherein the coating liquid is a melamine coating liquid with a mass fraction of 60-70%.

[0010] Preferably, in step 1, the drying temperature is 100–106°C and the drying time is 5–6 hours.

[0011] Further optimization involves soaking for 6-12 hours, freezing for 12-14 hours, and thawing for 8-10 hours in step 2.

[0012] In a further preferred embodiment, in step 2, the wood to be dried once is subjected to soaking in deionized water, freezing, thawing, and repeated multiple times before being dried again.

[0013] Further preferred, in step 2, the drying temperature is 100-106℃ and the drying time is 5-6 hours.

[0014] Further optimization involves, in step 3, water bath heating is performed during the impregnation process, with a water bath temperature of 55–65°C and an impregnation time of 12–14 hours.

[0015] Further optimization involves, in step 3, during the preparation of the impregnation solution, placing the flame retardant into deionized water, heating and stirring it in a water bath, wherein the water bath temperature is 75–85°C and the stirring time is 2–6 hours.

[0016] Further preferred, in step 3, the drying temperature is 100-106℃ and the drying time is 5-6 hours.

[0017] Further optimization involves using a drying temperature of 75–85°C and a drying time of 2–6 hours in step 4.

[0018] Further preferably, between step 3 and step 4, a step of subjecting the three-time dried wood to high-temperature heat treatment is included, wherein the high-temperature heat treatment temperature is 180-220°C and the high-temperature heat treatment time is 2-3 hours.

[0019] The present invention provides a method for preparing fire-retardant wood with both internal and external flame retardancy. It uses phosphorus-based flame retardants and boron-based flame retardants (ammonium polyphosphate and borax) to prepare an organic flame retardant, which is then impregnated into the wood to form a cross-linked structure. The wood surface is coated with a nitrogen-based flame retardant (melamine coating liquid) with low water solubility, which can form a synergistic effect of internal and external flame retardants, and finally obtain fire-retardant wood. Detailed Implementation

[0020] The present invention will be further explained below with reference to specific implementation schemes, but this explanation does not limit the scope of the invention.

[0021] To improve the fire resistance of wood, this invention provides a method for preparing wood with both internal and external fire retardancy, comprising the following steps:

[0022] Step 1: Dry the logs to obtain primary dried wood;

[0023] Step 2: The primary dried wood is sequentially soaked in deionized water, frozen, thawed, and dried to obtain secondary dried wood;

[0024] Step 3: Immerse the secondary dried wood in the impregnation solution and then dry the impregnated wood to obtain tertiary dried wood. The impregnation solution is a solution in which a flame retardant is dissolved in deionized water. The flame retardant is prepared by ammonium polyphosphate and borax in a mass ratio of 1 to 2.5:1. The flame retardant accounts for 5 to 12% of the mass of the impregnation solution.

[0025] Step 4: Apply the coating liquid to the surface of the three-time dried wood and dry it to obtain double flame-retardant wood, wherein the coating liquid is a melamine coating liquid with a mass fraction of 60-70%.

[0026] The method for preparing this dual internal and external flame-retardant wood involves using phosphorus-based flame retardants and boron-based flame retardants (ammonium polyphosphate and borax) to prepare an organic flame retardant, which is then impregnated into the wood to form a cross-linked structure. The wood surface is then coated with a nitrogen-based flame retardant (melamine coating liquid) with low water solubility, which creates a synergistic effect of internal and external flame retardants, ultimately resulting in flame-retardant wood.

[0027] As an improvement to the technical solution, in step 1, the drying temperature is 100-106℃ and the drying time is 5-6 hours.

[0028] As an improvement to the technical solution, in step 2, the soaking time is 6-12 hours, the freezing time is 12-14 hours, and the thawing time is 8-10 hours.

[0029] As an improvement to the technical solution, in step 2, the wood to be dried once is soaked in deionized water, frozen, thawed, and the process is repeated multiple times before being dried again.

[0030] As an improvement to the technical solution, in step 2, the drying temperature is 100-106℃ and the drying time is 5-6 hours.

[0031] As an improvement to the technical solution, in step 3, water bath heating is carried out during the impregnation process, with a water bath temperature of 55-65℃ and an impregnation time of 12-14 hours.

[0032] As an improvement to the technical solution, in step 3, during the preparation of the impregnation solution, the flame retardant is placed in deionized water, heated in a water bath and stirred, wherein the water bath temperature is 75-85℃ and the stirring time is 2-6 hours.

[0033] As an improvement to the technical solution, in step 3, the drying temperature is 100-106℃ and the drying time is 5-6 hours.

[0034] As an improvement to the technical solution, in step 4, the drying temperature is 75-85℃ and the drying time is 2-6 hours.

[0035] To further enhance the flame retardant properties of the wood, as an improvement to the technical solution, a step of subjecting the three-time dried wood to high-temperature heat treatment is included between step 3 and step 4. The high-temperature heat treatment temperature is 180-220°C, and the high-temperature heat treatment time is 2-3 hours.

[0036] Example 1

[0037] The preparation method of double flame-retardant wood includes the following steps:

[0038] Step 1: Dry the logs to obtain primary dried wood;

[0039] The logs were placed in a constant temperature drying oven, and the drying temperature was 103℃ for 6 hours.

[0040] Step 2: The primary dried wood is sequentially soaked in deionized water, frozen, thawed, and dried to obtain secondary dried wood;

[0041] The once-dried wood was soaked in deionized water for 6 hours, frozen in a freezer for 12 hours, thawed for 8 hours, and the cycle was repeated twice. Then it was placed in a constant temperature drying oven for drying at a temperature of 103°C for 6 hours.

[0042] Step 3: The secondary-dried wood is immersed in the impregnation solution and then dried to obtain tertiary-dried wood. The impregnation solution is a solution in which a flame retardant is dissolved in deionized water. The flame retardant is prepared by mixing ammonium polyphosphate and borax in a mass ratio of 1:1. The flame retardant accounts for 5% of the mass of the impregnation solution. During the preparation of the impregnation solution, the flame retardant is added to deionized water, and the solution is heated and stirred in a water bath at a temperature of 80°C for 3 hours. During the wood impregnation process, the wood is heated in a water bath at a temperature of 60°C for 12 hours. The drying temperature is 103°C and the drying time is 6 hours.

[0043] Step 4: Apply the coating liquid to the surface of the three-time dried wood and dry it to obtain double flame-retardant wood inside and out. The coating liquid is a 60% melamine coating liquid. The drying temperature is 80°C and the drying time is 3 hours.

[0044] Example 2

[0045] The preparation method of double flame-retardant wood includes the following steps:

[0046] Step 1: Dry the logs to obtain primary dried wood;

[0047] The logs were placed in a constant temperature drying oven, and the drying temperature was 100℃ for 6 hours.

[0048] Step 2: The primary dried wood is sequentially soaked in deionized water, frozen, thawed, and dried to obtain secondary dried wood;

[0049] The once-dried wood was soaked in deionized water for 6 hours, frozen in a freezer for 14 hours, thawed for 10 hours, and then placed in a constant temperature drying oven for drying at 100°C for 6 hours.

[0050] Step 3: The secondary-dried wood is immersed in the impregnation solution and then dried to obtain tertiary-dried wood. The impregnation solution is a solution in which a flame retardant is dissolved in deionized water. The flame retardant is prepared by ammonium polyphosphate and borax in a mass ratio of 1.5:1. The flame retardant accounts for 8% of the mass of the impregnation solution. During the preparation of the impregnation solution, the flame retardant is added to deionized water, and the solution is heated and stirred in a water bath at a temperature of 75°C for 6 hours. During the wood impregnation process, the wood is heated in a water bath at a temperature of 55°C for 14 hours. The drying treatment temperature is 100°C for 6 hours.

[0051] Step 4: Apply the coating liquid to the surface of the three-time dried wood and dry it to obtain double flame-retardant wood inside and out. The coating liquid is a 70% melamine coating liquid. The drying temperature is 75°C and the drying time is 6 hours.

[0052] Example 3

[0053] The preparation method of double flame-retardant wood includes the following steps:

[0054] Step 1: Dry the logs to obtain primary dried wood;

[0055] The logs were placed in a constant temperature drying oven at a temperature of 106℃ for 5 hours.

[0056] Step 2: The primary dried wood is sequentially soaked in deionized water, frozen, thawed, and dried to obtain secondary dried wood;

[0057] The once-dried wood was soaked in deionized water for 12 hours, frozen in a freezer for 12 hours, thawed for 8 hours, soaked again for 12 hours, frozen in a freezer for 12 hours, thawed for 8 hours, and then placed in a constant temperature drying oven for drying. The drying temperature was 106℃ and the drying time was 5 hours.

[0058] Step 3: The secondary-dried wood is immersed in the impregnation solution and then dried to obtain tertiary-dried wood. The impregnation solution is a solution in which a flame retardant is dissolved in deionized water. The flame retardant is prepared by ammonium polyphosphate and borax in a mass ratio of 2.5:1. The flame retardant accounts for 12% of the mass of the impregnation solution. During the preparation of the impregnation solution, the flame retardant is added to deionized water, and the solution is heated and stirred in a water bath at a temperature of 85°C for 2 hours. During the wood impregnation process, the wood is heated in a water bath at a temperature of 65°C for 12 hours. The drying temperature is 106°C and the drying time is 5 hours.

[0059] Step 4: Apply the coating liquid to the surface of the three-time dried wood and dry it to obtain double flame-retardant wood inside and out. The coating liquid is a melamine coating liquid with a mass fraction of 65%. The drying temperature is 85°C and the drying time is 2 hours.

[0060] Example 4

[0061] The difference from Example 1 is as follows:

[0062] After step 3, the three-time dried wood is subjected to high-temperature heat treatment at a temperature of 200°C for 2.5 hours. Then, step 4 is performed: the coating liquid is applied to the surface of the wood after high-temperature heat treatment and dried to obtain double flame-retardant wood.

[0063] Example 5

[0064] The difference from Example 2 is as follows:

[0065] After step 3, the three-time dried wood is subjected to high-temperature heat treatment at a temperature of 180°C for 3 hours. Then, step 4 is performed: the coating liquid is applied to the surface of the wood after high-temperature heat treatment and dried to obtain double flame-retardant wood.

[0066] Example 6

[0067] The difference from Example 3 is as follows:

[0068] After step 3, the three-time dried wood is subjected to high-temperature heat treatment at a temperature of 220°C for 2 hours. Then, step 4 is performed: the coating liquid is applied to the surface of the wood after high-temperature heat treatment and dried to obtain double flame-retardant wood.

[0069] The following tests were conducted on the internally and externally flame-retardant wood and logs obtained in Examples 1-6:

[0070] 1. At a thermal radiation intensity of 50kW / m2 Below, cone calorimetry experiments were conducted on the logs and the double-layered flame-retardant wood obtained in Examples 1-6. The results showed that the peak heat release rate of the logs was 227 kW / m². 2 The peak heat release rate of the double flame-retardant wood obtained in Examples 1-6 was lower than that of the log. Specifically, the heat release rate of the double flame-retardant wood obtained in Examples 1-3 was 18.2-22.7%, and the heat release rate of the double flame-retardant wood obtained in Examples 4-6 was 31.8-35.6%.

[0071] 2. Thermogravimetric analysis (TGA) experiments were conducted on the logs and the double-fire-retardant wood obtained in Examples 1-6. The experimental atmosphere was nitrogen, the flow rate was 50 ml / min, and the temperature range was 40℃ to 800℃. The results showed that the char residue of the logs at 800℃ was 17.5%. The char residue of the double-fire-retardant wood obtained in Examples 1-6 was higher than that of the logs. Specifically, the char residue of the double-fire-retardant wood obtained in Examples 1-3 was increased by 114% to 122%, and that of the double-fire-retardant wood obtained in Examples 4-6 was increased by 138% to 160%.

[0072] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method for preparing double-layered flame-retardant wood, characterized in that, Includes the following steps: Step 1: Dry the logs to obtain primary dried wood; Step 2: The primary dried wood is sequentially soaked in deionized water, frozen, thawed, and dried to obtain secondary dried wood; Step 3: Immerse the secondary-dried wood in the impregnation solution and then dry the impregnated wood to obtain tertiary-dried wood. The impregnation solution is a solution formed by dissolving a flame retardant in deionized water. The flame retardant is prepared by ammonium polyphosphate and borax in a mass ratio of 1~2.5:1, and the flame retardant accounts for 5~12% of the mass of the impregnation solution. Step 4: Apply the coating liquid to the surface of the wood that has been dried three times and dry it to obtain fire-retardant wood with both internal and external surfaces. The coating liquid is a melamine coating liquid with a mass fraction of 60-70%. In step 3, water bath heating is carried out during the impregnation process. The water bath temperature is 55~65℃ and the impregnation time is 12~14 hours. Between steps 3 and 4, there is also a step of subjecting the three-time dried wood to high-temperature heat treatment, wherein the high-temperature heat treatment temperature is 180~220℃ and the high-temperature heat treatment time is 2~3 hours.

2. The method for preparing double-layered flame-retardant wood according to claim 1, characterized in that: In step 1, the drying temperature is 100~106℃ and the drying time is 5~6 hours.

3. The method for preparing double-layered flame-retardant wood according to claim 1, characterized in that: In step 2, the soaking time is 6 to 12 hours, the freezing time is 12 to 14 hours, and the thawing time is 8 to 10 hours.

4. The preparation method of the double flame-retardant wood according to claim 1, characterized in that: In step 2, the wood to be dried is soaked in deionized water, frozen, thawed, and this process is repeated multiple times before the wood is dried again.

5. The preparation method of the double flame-retardant wood according to claim 1, characterized in that: In step 2, the drying temperature is 100~106℃ and the drying time is 5~6 hours.

6. The preparation method of the double flame-retardant wood according to claim 1, characterized in that: In step 3, during the preparation of the impregnation solution, the flame retardant is placed in deionized water, heated in a water bath and stirred. The water bath temperature is 75~85℃, and the stirring time is 2~6h.

7. The preparation method of the double flame-retardant wood according to claim 1, characterized in that: In step 3, the drying temperature is 100~106℃ and the drying time is 5~6 hours.

8. The preparation method of the double flame-retardant wood according to claim 1, characterized in that: In step 4, the drying temperature is 75~85℃ and the drying time is 2~6 hours.