Smoke-suppression flame-retardant formaldehyde-free decorative veneer faced fir plywood and preparation method thereof

Abstract

A smoke-suppressing, flame-retardant, formaldehyde-free decorative veneer plywood made of fir wood and its preparation method are disclosed. The method involves impregnating fir veneer with a piperazine aqueous solution, washing, and drying. The treated fir veneer is then impregnated with a 2-hydroxyphosphonic acid-acetic acid aqueous solution, rinsed, and dried to obtain a flame-retardant fir veneer. A flame-retardant adhesive is prepared by mixing flame retardant P-CS-H and polyvinyl acetate emulsion at a mass ratio of 3-7:10. The flame-retardant fir veneer is used as the wood flame-retardant layer, a mixture of the flame-retardant adhesive and flour is used as the flame-retardant glue layer, and reconstituted decorative veneer is used as the surface decoration layer. The plywood is assembled in the following order: surface decoration layer, flame-retardant glue layer, wood flame-retardant layer, flame-retardant glue layer, and surface decoration layer. The plywood is then subjected to cold pressing and hot pressing treatments. This yields a formaldehyde-free decorative veneer plywood with excellent flame-retardant and smoke-suppressing properties.

Description

Technical Field

[0001] This invention relates to engineered wood panel manufacturing technology, specifically to a smoke-suppressing, flame-retardant, formaldehyde-free decorative veneer fir engineered wood panel and its preparation method. Background Technology

[0002] Chinese fir wood contains high levels of volatile compounds such as terpenes and phenols, which can exacerbate flame propagation and release large amounts of organic smoke during combustion, reducing its flame-retardant effect and jeopardizing safety. Traditional flame-retardant methods mainly rely on single impregnation with phosphorus-nitrogen flame retardants to improve flame retardancy. While this can inhibit combustion, it leads to increased smoke release and does not address smoke suppression performance. Summary of the Invention

[0003] In view of the above-mentioned research and development issues, this invention provides a formaldehyde-free decorative veneer engineered wood panel made of Chinese fir with excellent flame retardant and smoke suppression properties, and its preparation method. Specifically, it provides a novel flame retardant system that utilizes the specific molecular structure of the flame retardant to synergistically work with the microstructure and contents of Chinese fir itself, thereby improving flame retardant efficiency while effectively reducing smoke.

[0004] The specific technical solution is as follows: Firstly, a method for preparing smoke-suppressing, flame-retardant, formaldehyde-free decorative veneer fir plywood is provided, characterized by comprising: Flame-retardant fir veneer is used as the wood flame-retardant layer, a mixture of flame-retardant adhesive and flour is used as the flame-retardant glue layer, and reconstituted decorative veneer is used as the surface decoration layer. The layers are assembled in the following order: surface decoration layer, flame-retardant glue layer, wood flame-retardant layer, flame-retardant glue layer, and surface decoration layer. After cold pressing and hot pressing, the resulting smoke-suppressing, flame-retardant, formaldehyde-free decorative veneer fir plywood is obtained. The flame-retardant cedar veneer is prepared by the following method: The cedar veneer was impregnated with a piperazine aqueous solution, rinsed, and then dried at 30-50°C. The treated cedar veneer was then impregnated with a 2-hydroxyphosphonic acid aqueous solution, rinsed, and dried at 60-70°C. The temperature was then slowly increased to 80-90°C for further drying, causing the piperazine and 2-hydroxyphosphonic acid to react with the wood in the following chemical reaction: ;

[0005] The flame-retardant adhesive is prepared by the following method: The flame retardant P-CS-H and polyvinyl acetate emulsion are mixed evenly at a mass ratio of 3~7:10, and then stirred at 60~70℃ to obtain the flame retardant adhesive. The flame retardant P-CS-H is prepared by the following method: A solution of 2-hydroxyphosphonic acid, chitosan acetate, and piperazine in a mass ratio of 1:10~15:1~5 is mixed, and the mixture is slowly heated to 80~90℃ and held for 60~90 min, causing the 2-hydroxyphosphonic acid, chitosan, and piperazine to undergo the following chemical reaction: ;

[0006] The flame retardant P-CS-H was then obtained by filtration and washing. The chitosan-acetic acid solution is obtained by mixing chitosan and acetic acid aqueous solution with a mass ratio of 1:10~11, and the piperazine aqueous solution is obtained by mixing piperazine and water with a mass ratio of 1:9~10.

[0007] In the preparation of the flame-retardant fir veneer, The impregnation process with piperazine aqueous solution includes: placing cedar veneer in an impregnation tank, evacuating to -0.30 to -0.25 MPa and maintaining it for 10 to 20 minutes, injecting a 17 to 25 wt% piperazine aqueous solution under this negative pressure condition to completely immerse the veneer, and then pressurizing to 0.7 to 1.0 MPa and maintaining it for 2 to 4 hours; The impregnation process of the 2-hydroxyphosphonic acid aqueous solution includes: placing the treated cedar veneer in the impregnation tank again, evacuating to -0.30 to -0.25 MPa and maintaining it for 10 to 20 minutes, injecting a 10 to 15 wt% 2-hydroxyphosphonic acid aqueous solution under this negative pressure, and after the veneer is completely submerged, pressurizing to 0.7 to 1.0 MPa and maintaining it for 2 to 4 hours.

[0008] The application rate of the mixture of flame-retardant adhesive and flour is 210~240 g / m³. 2 The flame-retardant adhesive and flour are mixed in a mass ratio of 7:2.0~3.5.

[0009] The cold pressing conditions are 30~40℃ and 0.15~0.20MPa for 60~70min, and the hot pressing conditions are 110~120℃ and 1.1~1.5MPa for 10~15min.

[0010] Also provided is a smoke-suppressing, flame-retardant, formaldehyde-free decorative veneer plywood made by the above preparation method.

[0011] The plywood prepared according to this invention not only meets the requirements for flame retardancy but also achieves excellent smoke suppression. This invention constructs two smoke suppression barriers through a core and surface layer. During combustion, the smoke components released from the core layer are transformed into large-molecule volatile substances through the core layer's action. The surface layer intercepts these large-molecule volatile substances by utilizing a gel-like char layer formed from phosphorylated chitosan and flour under high temperature. Detailed Implementation

[0012] Unless otherwise stated, the numerical range "A~B" in this invention refers to A or above (greater than or equal to A) and B or below (less than or equal to B). When referring to the concept of room temperature, it usually means between 22 and 25°C, and sometimes between 20 and 28°C depending on the process. In actual industry, different fields have different understandings of room temperature or room temperature. However, from the perspective of the implementation and application of patent law, it should be regarded as limited to achieving the purpose of the invention, and should not be limited to a narrow empirical range in a certain field.

[0013] In this invention, if some processes do not specify a temperature or room temperature limit, they should generally be considered to be carried out at room temperature or room temperature. Those skilled in the art can control the process conditions without special knowledge, unless otherwise specified or should be understood by those skilled in the art.

[0014] This invention discloses a formaldehyde-free fir veneer engineered wood panel prepared by the following steps, which can simultaneously meet the requirements of excellent flame retardancy and smoke suppression.

[0015] Step 1: The cedar veneer was impregnated with a piperazine aqueous solution, washed, and then dried at 30-50 ℃. The treated cedar veneer was then impregnated with a 2-hydroxyphosphonic acid aqueous solution, rinsed, and then dried at 60-70 ℃ and 80-90 ℃ respectively to obtain flame-retardant cedar veneer.

[0016] Through this dual impregnation and drying process, piperazine and 2-hydroxyphosphonic acid react with the chemical structure of the wood inside the veneer in the following ways:

[0017] The thickness of the cedar veneer is 1.7~3.6mm.

[0018] The impregnation process with piperazine aqueous solution includes: placing cedar veneer in an impregnation tank, evacuating to -0.30 to -0.25 MPa and maintaining the vacuum for 10 to 20 minutes, injecting piperazine aqueous solution under this negative pressure condition to completely submerge the veneer; then pressurizing to 0.7 to 1.0 MPa and maintaining the pressure for 2 to 4 hours to promote the penetration of piperazine aqueous solution into the wood.

[0019] The concentration of the piperazine aqueous solution is 17~25wt%.

[0020] The impregnated cedar veneer is then rinsed with enough water to cover it. After rinsing, the cedar veneer is placed in a forced-air drying oven for drying at 30-50°C for 30-40 minutes.

[0021] The impregnation process of the 2-hydroxyphosphonic acid aqueous solution includes: placing the treated cedar veneer in the impregnation tank again, evacuating to -0.30~-0.25MPa and maintaining it for 10~20min, injecting the 2-hydroxyphosphonic acid aqueous solution under this negative pressure, and after the veneer is completely immersed, pressurizing to 0.7~1.0MPa and maintaining it for 2~4h to promote the penetration of the 2-hydroxyphosphonic acid aqueous solution into the wood.

[0022] The concentration of the aqueous solution of 2-hydroxyphosphonic acid is 10~15wt%.

[0023] The impregnated cedar veneer is then rinsed with clean water. The rinsed cedar veneer is placed in a forced-air drying oven for drying treatment, specifically including first drying at 60℃~70℃ for 20~40 minutes, and then raising the temperature to 80~90℃ at a rate of 2~3℃ / min and drying for 60~90 minutes.

[0024] Step 2: A solution of 2-hydroxyphosphonic acid, chitosan acetic acid, and piperazine aqueous solution in a mass ratio of 1:10~15:1~5 was mixed and heated to 80~90℃ at a heating rate of 5~6℃ / min for 60~90min. The mixture was then filtered and washed to obtain flame retardant P-CS-H.

[0025] The chitosan-acetic acid solution was obtained by mixing chitosan and acetic acid aqueous solution at a mass ratio of 1:10 and stirring for 30 minutes. The piperazine aqueous solution was obtained by mixing piperazine and water at a mass ratio of 1:9 and stirring for 20 minutes.

[0026] The above reaction yielded a yellowish-brown precipitate, which was filtered and washed with deionized water to obtain the P-CS-H.

[0027] The flame retardant P-CS-H is prepared by the following method: A solution of 2-hydroxyphosphonic acid, chitosan acetic acid, and piperazine aqueous solution in a mass ratio of 1:10~15:1~5 was mixed and the mixture was slowly heated to 80~90℃ and reacted for 60~90 min. The reaction formula is as follows.

[0028]

[0029] Then, flame retardant P-CS-H and polyvinyl acetate emulsion are mixed evenly at a mass ratio of 3~7:10, and stirred at 60~70℃ for 45~55 minutes to obtain flame retardant adhesive.

[0030] The polyvinyl acetate emulsion is also referred to as VAE emulsion below. In the examples and comparative examples, a polyvinyl acetate emulsion with a solid content of 54.5% and a viscosity of 2000 mPa·s was specifically used.

[0031] The flame-retardant adhesive should be stored in a sealed, light-proof container at room temperature for no more than one week.

[0032] Step 3: Flame-retardant fir veneer is used as the wood flame-retardant layer, a mixture of flame-retardant adhesive and flour is used as the flame-retardant glue layer, and reconstituted decorative veneer is used as the surface decoration layer. The veneer is assembled in the order of surface decoration layer, flame-retardant glue layer, wood flame-retardant layer, flame-retardant glue layer, and surface decoration layer. After cold pressing and hot pressing, smoke-suppressing, flame-retardant, formaldehyde-free decorative veneer fir plywood is produced.

[0033] The mixture is prepared by mixing flame-retardant adhesive and flour at a mass ratio of 7:2.0~3.5. The flame-retardant adhesive should be used immediately after opening the package for mixing, and should be used immediately for paving after mixing. The application rate of the mixture is 210~240 g / m². 2 .

[0034] The reconstituted decorative veneer is not limited, but in the examples and comparative examples, it was specifically purchased from Han Shifu Integrated Home Furnishings Co., Ltd., with a specification of 0.4mm.

[0035] The cold pressing conditions are 30~40℃ and 0.15~0.20MPa for 60-70 minutes.

[0036] The hot pressing conditions are 110~120℃ and 1.1~1.5MPa for 10~15min.

[0037] It is generally believed that flour and chitosan, as organic materials with high carbon content, can produce a lot of residual char when heated and burned. However, the release of water vapor and other gases with a certain pressure from the core layer can have a certain destructive effect on the formation of the dense char layer on the surface. Due to the uncertainty of their own char-forming and combustible properties, it is difficult to predict whether the smoke generated by the combustion of the bottom layer can be captured.

[0038] However, the flame-retardant system constructed by this invention, when heated, catalyzes the conversion of small-molecule smoke precursors that are prone to escape into large-molecule volatile substances through a specific flame-retardant system in the core layer. When passing through the surface layer, the phosphorylated chitosan and flour form a gel-like substance under high temperature, which intercepts the large-molecule volatile substances generated in the core layer through physical adsorption, thus achieving smoke suppression. The transformation of the core layer not only overcomes the problem of the surface layer's difficulty in intercepting small-molecule precursors, but also avoids the combustion chain reaction between small-molecule precursors and organic substances such as chitosan on the surface layer.

[0039] On the other hand, the main difference in flame retardants between the surface and core layers lies in chitosan. Chitosan acts as a carbon source. The surface layer is a simple blend forming a PON layer and a POC layer formed under the action of chitosan. The core layer is a combination with wood, which forms POC during pyrolysis, while nitrogen is released as NH3 gas. This release causes the aforementioned carbon layer formed on the surface to expand under the action of airflow, and this airflow also promotes the interception efficiency of large molecular volatile substances.

[0040] The following describes in detail the embodiments and comparative examples of applying the present invention.

[0041] Example 1: (1) Place a 3.6 mm thick fir veneer in an impregnation tank, evacuate to -0.25 MPa and maintain for 10 min, then inject a 17 wt% piperazine aqueous solution under this negative pressure condition to completely immerse the veneer; subsequently pressurize to 0.7 MPa and maintain for 2 h. After removal, rinse with enough water to cover the veneer and place in a forced-air drying oven to dry at 30 °C for 30 min.

[0042] Next, the treated veneer was placed back into the impregnation tank, and a vacuum was drawn to -0.25 MPa and maintained for 10 min. Under this negative pressure, a 10 wt% aqueous solution of 2-hydroxyphosphonic acid was injected, and the veneer was completely immersed. Then, the pressure was increased to 0.7 MPa and maintained for 2 h. After removing the veneer, it was rinsed with clean water and placed in a forced-air drying oven at 60°C for 20 min. Then, the temperature was increased from 60°C to 80°C at a rate of 3°C / min and maintained for 60 min to obtain flame-retardant fir veneer.

[0043] (2) Chitosan and acetic acid solution with a mass ratio of 1:10 were mixed and stirred for 30 min to obtain chitosan acetic acid solution. Piperazine and water with a mass ratio of 1:9 were mixed and stirred for 20 min to obtain piperazine aqueous solution.

[0044] A mixture of 2-hydroxyphosphonic acid, chitosan acetic acid solution, and piperazine aqueous solution in a mass ratio of 1:15:1 was thoroughly mixed and then heated to 80°C at a rate of 6°C / min for 60 min to obtain a yellowish-brown precipitate. After filtration, the precipitate was washed with deionized water to obtain flame retardant P-CS-H.

[0045] Next, flame retardant P-CS-H and VAE emulsion were mixed evenly at a mass ratio of 3:10 and stirred at 60°C for 45 minutes to obtain flame retardant adhesive.

[0046] (3) Using flame-retardant veneer as the wood flame-retardant layer, a mixture of flame-retardant adhesive and flour (mass ratio 7:3.5) as the flame-retardant adhesive layer, and reconstituted decorative veneer as the surface decorative layer, the two layers are assembled in the following order: surface decorative layer, flame-retardant adhesive layer, wood flame-retardant layer, flame-retardant adhesive layer, and surface decorative layer. After cold pressing at 30℃ and 0.15MPa for 60 minutes, the mixture is hot-pressed at 110℃ and 1.1MPa for 10 minutes to obtain smoke-suppressing and flame-retardant formaldehyde-free fir veneer plywood. The amount of flame-retardant adhesive applied to the surface layer is 210g / m². 2 .

[0047] Example 2: (1) Place a 1.7 mm thick fir veneer in an impregnation tank, evacuate to -0.30 MPa and maintain for 20 min, then inject a 25 wt% piperazine aqueous solution under this negative pressure to completely immerse the veneer; subsequently pressurize to 1.0 MPa and maintain for 4 h. After removal, rinse with enough water to cover the veneer and place in a forced-air drying oven to dry at 50 ℃ for 40 min.

[0048] Next, the treated veneer was placed back into the impregnation tank, and a vacuum was drawn to -0.30 MPa and maintained for 20 min. Under this negative pressure, a 15% (w / w) aqueous solution of 2-hydroxyphosphonic acid was injected, and the veneer was completely immersed. Then, the pressure was increased to 1.0 MPa and maintained for 4 h. After removing the veneer, it was rinsed with clean water and placed in a forced-air drying oven at 70°C for 40 min. The temperature was then increased from 70°C to 90°C at a rate of 2°C / min and maintained for 90 min.

[0049] (2) Chitosan and acetic acid solution with a mass ratio of 1:10 were mixed and stirred for 30 min to obtain chitosan acetic acid solution. Piperazine and water with a mass ratio of 1:9 were mixed and stirred for 20 min to obtain piperazine aqueous solution.

[0050] A mixture of 2-hydroxyphosphonic acid, chitosan acetic acid solution, and piperazine aqueous solution in a mass ratio of 1:10:5 was thoroughly mixed and then heated to 90°C at a rate of 5°C / min for 90 min to obtain a yellowish-brown precipitate. After filtration, the precipitate was washed with deionized water to obtain P-CS-H.

[0051] Next, flame retardant P-CS-H and VAE emulsion were mixed evenly at a mass ratio of 7:10 and stirred at 70°C for 55 minutes to obtain flame retardant adhesive.

[0052] (3) Using flame-retardant veneer as the wood flame-retardant layer, a mixture of flame-retardant adhesive and flour (mass ratio 7:2.0) as the flame-retardant adhesive layer, and reconstituted decorative veneer as the surface decorative layer, the two layers are assembled in the following order: surface decorative layer, flame-retardant adhesive layer, wood flame-retardant layer, flame-retardant adhesive layer, and surface decorative layer. After cold pressing at 40℃ and 0.20MPa for 70 minutes, and then hot pressing at 120℃ and 1.5MPa for 15 minutes, a smoke-suppressing and flame-retardant formaldehyde-free fir veneer plywood is obtained. The amount of flame-retardant adhesive applied to the surface layer is 240g / m². 2 .

[0053] Based on Example 2, some processes were modified to conduct comparative examples 1-2, while other processes remained the same as in Example 2.

[0054] Comparative Example 1: Based on Example 2, only flame-retardant adhesive is used as the flame-retardant adhesive layer for preform assembly, while the amount of adhesive applied and other process steps remain unchanged.

[0055] Comparative Example 2: Based on Example 2, only the following process was changed: In the second impregnation of the cedar veneer, the 2-hydroxyphosphonic acid aqueous solution is not impregnated; specifically: Next, the treated veneer was placed back into the impregnation tank, and a vacuum was drawn to -0.30 MPa and maintained for 20 minutes. Water was then injected under this negative pressure until the veneer was completely submerged. The pressure was then increased to 1.0 MPa and maintained for 4 hours. After removing the veneer, it was rinsed with clean water and placed in a forced-air drying oven at 70°C for 40 minutes. The temperature was then increased from 70°C to 90°C at a rate of 2°C / min and maintained for 90 minutes.

[0056] Table 1: Performance Test Data of Examples and Comparative Examples

Claims

1. A method for preparing a smoke-suppressing, flame-retardant, formaldehyde-free decorative veneer fir plywood, characterized in that, include: Flame-retardant fir veneer is used as the wood flame-retardant layer, a mixture of flame-retardant adhesive and flour is used as the flame-retardant glue layer, and reconstituted decorative veneer is used as the surface decoration layer. The layers are assembled in the following order: surface decoration layer, flame-retardant glue layer, wood flame-retardant layer, flame-retardant glue layer, and surface decoration layer. After cold pressing and hot pressing, the resulting smoke-suppressing, flame-retardant, formaldehyde-free decorative veneer fir plywood is obtained. The flame-retardant cedar veneer is prepared by the following method: The cedar veneer was impregnated with a piperazine aqueous solution, rinsed, and then dried at 30-50°C. The treated cedar veneer was then impregnated with a 2-hydroxyphosphonic acid aqueous solution, rinsed, and dried at 60-70°C. The temperature was then slowly increased to 80-90°C for further drying, causing the piperazine and 2-hydroxyphosphonic acid to react with the wood as follows: ； The flame-retardant adhesive is prepared by the following method: The flame retardant P-CS-H and polyvinyl acetate emulsion are mixed evenly at a mass ratio of 3~7:10, and then stirred at 60~70℃ to obtain the flame retardant adhesive. The flame retardant P-CS-H is prepared by the following method: A solution of 2-hydroxyphosphonic acid, chitosan acetate, and piperazine in a mass ratio of 1:10~15:1~5 is mixed, and the mixture is slowly heated to 80~90℃ and held for 60~90 min, causing the following reaction to occur in the 2-hydroxyphosphonic acid, chitosan, and piperazine: ； The flame retardant P-CS-H was then obtained by filtration and washing. The chitosan-acetic acid solution is obtained by mixing chitosan and acetic acid aqueous solution with a mass ratio of 1:10~11, and the piperazine aqueous solution is obtained by mixing piperazine and water with a mass ratio of 1:9~10.

2. The preparation method according to claim 1, wherein, In the preparation of the flame-retardant fir veneer, The impregnation process with piperazine aqueous solution includes: placing cedar veneer in an impregnation tank, evacuating to -0.30 to -0.25 MPa and maintaining it for 10 to 20 minutes, injecting a 17 to 25 wt% piperazine aqueous solution under this negative pressure condition to completely immerse the veneer, and then pressurizing to 0.7 to 1.0 MPa and maintaining it for 2 to 4 hours; The impregnation process of the 2-hydroxyphosphonic acid aqueous solution includes: placing the treated cedar veneer in the impregnation tank again, evacuating to -0.30 to -0.25 MPa and maintaining it for 10 to 20 minutes, injecting a 10 to 15 wt% 2-hydroxyphosphonic acid aqueous solution under this negative pressure, and after the veneer is completely submerged, pressurizing to 0.7 to 1.0 MPa and maintaining it for 2 to 4 hours.

3. The preparation method according to claim 1, wherein, The application rate of the mixture of flame-retardant adhesive and flour is 210~240 g / m³. 2 The flame-retardant adhesive and flour are mixed in a mass ratio of 7:2.0~3.

5.

4. The preparation method according to claim 1, wherein, The cold pressing conditions are 30~40℃ and 0.15~0.20MPa for 60~70 minutes. The hot pressing conditions are 110~120℃ and 1.1~1.5MPa for 10~15min.

5. A smoke-suppressing, flame-retardant, formaldehyde-free decorative veneer plywood made by the preparation method described in any one of claims 1 to 4.

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