Reconstituted reed-based panel based on full bio-based adhesive and method for preparing the same

Abstract

The application discloses a kind of based on full biological base adhesive recombination reed base artificial board and preparation method thereof, the preparation method includes the following steps: S1, reed stem is pretreated using alkaline solution, and pretreated reed stem is obtained;S2, citric acid, glucose, tannic acid, p-toluenesulfonic acid, melamine and water are mixed to react, polyvinyl alcohol is added, and full biological base adhesive is obtained;S3, pretreated reed stem is immersed in full biological base adhesive, and the reed stem after impregnation is obtained;S4, the reed stem after impregnation is stacked along the fiber direction, and is sequentially cold-pressed, heat-treated, to obtain based on full biological base adhesive recombination reed base artificial board.The recombination reed base artificial board based on full biological base adhesive of the application has excellent mechanical strength, good flame retardant performance and dimensional stability, and can widen the application scenarios of reed artificial board in home decoration, structural building, transportation and other fields.

Description

Technical Field

[0001] This invention belongs to the field of reed-based engineered wood products preparation, specifically relating to a recombinant reed-based engineered wood product based on a fully bio-based adhesive and its preparation method. Background Technology

[0002] In recent years, to alleviate the shortage of forest resources in my country, the use of reed stems as raw material for the preparation of engineered wood products has become a research hotspot. However, reed stems are similar to straw materials, with their outer surface rich in a large amount of siliceous waxy layer, making it difficult for commonly used formaldehyde-based adhesives (urea-formaldehyde resin, phenolic resin, etc.) to penetrate and form an effective bond. This seriously affects the mechanical properties and water resistance of reed engineered wood products, and they also contain volatile organic compounds (VOCs) such as formaldehyde and phenol. Currently, pretreatment of reed stems can solve the problem of poor adhesive penetration, but this method generates a large amount of waste liquid. On the other hand, expensive isocyanate-based adhesives can directly produce reed engineered wood products with the advantages of being formaldehyde-free, having high mechanical strength, and good water resistance, but their production process easily generates toxic and harmful VOCs, which cannot yet fully meet social needs. In addition, reed stems are flammable biomass materials, and the density of organic reed engineered wood products produced by existing methods is usually 0.65 g / cm³. 3 ~0.85g / cm 3 This limits the application range of the boards made from reeds. Therefore, finding a green and environmentally friendly reed-based engineered wood product is of great significance for broadening the application scenarios of reed-based engineered wood products in home decoration, structural construction, transportation and other fields, and realizing the high-value-added utilization of reed resources. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a recombinant reed-based artificial board with excellent mechanical strength, flame retardant properties and good dimensional stability based on a fully bio-based adhesive, and its preparation method.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution.

[0005] A method for preparing recombinant reed-based engineered wood panels based on a fully bio-based adhesive includes the following steps:

[0006] S1. The reed stems are pretreated with an alkaline solution and then dried to obtain pretreated reed stems;

[0007] S2. Mix citric acid, glucose, tannic acid, p-toluenesulfonic acid, melamine and water, react them, and add polyvinyl alcohol to obtain a fully bio-based adhesive.

[0008] S3. The pretreated reed stems obtained in step S1 are immersed in the all-bio-based adhesive obtained in step S2, and after draining and drying, the immersed reed stems are obtained.

[0009] S4. The impregnated reed stems obtained in step S3 are stacked and laid out along the fiber direction, and then subjected to cold pressing and hot pressing in sequence to obtain a recombinant reed-based artificial board based on a fully bio-based adhesive.

[0010] In the preferred embodiment of the above preparation method, in step S2, the amounts of each raw material required for preparing the fully bio-based adhesive are as follows (by mass): citric acid 150-200 parts, glucose 150-200 parts, tannic acid 50-100 parts, p-toluenesulfonic acid 2.8-4.0 parts, melamine 9.8-12.6 parts, water 250-600 parts, and polyvinyl alcohol 5.25-10.25 parts.

[0011] In the above preparation method, preferably, in step S1, the mass percentage concentration of the alkaline solution is 2.5% to 3.5%, and the alkaline solution is at least one of sodium hydroxide solution, potassium hydroxide solution, calcium oxide solution, and sodium carbonate solution; the mass ratio of the alkaline solution to the reed stem is 10 to 20: 100 to 120.

[0012] In the above-mentioned preparation method, preferably, in step S4, the pressure of the cold pressing treatment is 20MPa to 35MPa, and the time of the cold pressing treatment is 15min to 30min; the hot pressing treatment is segmented hot pressing, and the specific process of the segmented hot pressing is as follows: at a temperature of 160℃ to 200℃, hot pressing is performed at 4.5MPa to 9.5MPa for 5min to 12min, and then hot pressing is performed at 3.5MPa to 6.5MPa for 5min to 8min.

[0013] In the above preparation method, preferably, in step S2, the reaction temperature is 90℃~110℃ and the reaction time is 2.5h~3.5h.

[0014] In the above preparation method, preferably, in step S3, the impregnation process is as follows: vacuum impregnation and pressure impregnation are performed sequentially; the vacuum impregnation time is 10 min to 20 min, the pressure impregnation time is 30 min to 60 min, and the pressure of the pressure impregnation is 0.3 MPa to 0.5 MPa.

[0015] In the preferred embodiment of the above preparation method, step S1 further includes the following treatment before use of the reed stems: removing reed leaves and flowers from the reed stems, washing the surface of the reed stems, and then rolling and drying the reed stems to a moisture content of 2% to 8%; the washing is done with water, and the rolling is done with an electric roller press; the specific process of the pretreatment is as follows: wetting the reed stems with an alkaline solution; the drying temperature is 95℃ to 105℃, and the moisture content of the pretreated reed stems is 1% to 3%.

[0016] In the above preparation method, preferably, in step S3, the all-bio-based adhesive further includes the following treatment before use: diluting the all-bio-based adhesive obtained in step S2 to a solid content of 15% to 20%; the drying temperature is 50℃ to 80℃; and the moisture content of the reed stems after impregnation is 10% to 15%.

[0017] As a general technical concept, the present invention also provides a recombinant reed-based artificial board based on a fully bio-based adhesive prepared by the above-described preparation method.

[0018] Preferably, the reconstituted reed-based engineered wood panel based on the aforementioned fully bio-based adhesive has a thickness of 8 mm to 15 mm and a density of 0.95 g / cm³. 3 ~1.13g / cm 3 .

[0019] (1) This invention provides a method for preparing recombinant reed-based artificial board based on fully bio-based adhesive. First, the reed stems are pretreated with an alkaline solution, then impregnated with a fully bio-based adhesive, and then stacked, cold-pressed, and hot-pressed to obtain the recombinant reed-based artificial board based on the fully bio-based adhesive. The alkaline solution used in this invention addresses several issues. First, compared to traditional methods of treating reed stems, which require large doses of acidic solutions (such as hydrochloric acid, sulfuric acid, and sodium chlorite) and generate significant wastewater discharge leading to severe environmental pollution, this invention uses a low-concentration, low-dose alkaline solution for pretreatment. The solution is applied through wetting, allowing the reed stems to uniformly absorb the alkaline solution. Further high-temperature drying increases the overall alkalinity of the stems, enabling the etching of the silicified waxy layer on the reed stem surface. Moisture evaporates as steam, resulting in no pollutants generated. Second, unlike traditional adhesives which require the addition of a curing agent and involve complex processes, the alkaline solution used in this invention offers multiple benefits with a single application, eliminating the need for additional curing agents and improving the curing efficiency of fully bio-based adhesives. The fully bio-based adhesive used in this invention is synthesized from natural, biodegradable, and renewable green and environmentally friendly materials, ensuring that the product will not produce any toxic or harmful volatile organic compounds during subsequent use, thus achieving the production of formaldehyde-free reed-based engineered wood panels. In addition, the fully bio-based adhesive is acidic, and pre-treating the alkaline substances in the reed stems can neutralize the acidity or alkalinity of the board.

[0020] (2) Compared with the defects of reed-based artificial boards prepared by existing processes, such as low mechanical properties, poor flame retardancy, and poor dimensional stability, this invention provides a reconstituted reed-based artificial board based on a fully bio-based adhesive, with a density of 0.95 g / cm³. 3 ~1.13g / cm 3It has advantages such as excellent mechanical strength, good flame retardant properties and good dimensional stability. Specifically, the high density not only makes the board difficult to burn completely in a short time, giving it flame-retardant properties, but also makes it difficult for moisture to penetrate the interior of the board, significantly improving the water resistance of the board. This broadens the application scenarios of reed-based artificial boards in home decoration, structural construction, transportation and other fields, realizing the high added value utilization of reed resources. Attached Figure Description

[0021] Figure 1 The graph shows a comparison of the bending strength of the recombinant reed-based artificial boards based on fully bio-based adhesives prepared in Examples 1-3 of this invention.

[0022] Figure 2 The figures show a comparison of the dimensional stability of the recombinant reed-based engineered wood panels based on fully bio-based adhesives obtained in Examples 2-3 of this invention. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings and specific preferred embodiments, but this does not limit the scope of protection of the present invention. All materials and instruments used in the following embodiments are commercially available.

[0024] Example 1:

[0025] A method for preparing a recombinant reed-based engineered wood panel based on a fully bio-based adhesive according to the present invention includes the following steps:

[0026] (1) Remove the leaves and flowers from the reed stems and use a high-pressure water gun to remove the mud, gravel and other impurities from the surface of the reed stems. Then, use an electric roller press to roll the reed stems, that is, to spread the fibers of the reed stems radially to increase their contact area with the alkaline solution. Subsequently, dry them to a moisture content of 8% and cut them into lengths of 100-150mm for subsequent laying, thus obtaining the treated reed stems.

[0027] (2) The treated reed stems obtained in step (1) are uniformly wetted with sodium hydroxide solution, and then dried at 103°C until the moisture content is 1% to obtain activated reed stems. The mass ratio of sodium hydroxide solution to treated reed stems is 10:100, and the mass percentage concentration of sodium hydroxide solution is 3%.

[0028] In this step, sodium hydroxide solution is used for activation treatment, which produces no waste liquid. The moisture evaporates as water vapor at high temperature, while the residual sodium hydroxide rapidly activates the reed stems at high temperature, exposing more reed fibers for effective bonding with the all-bio-based adhesive. At the same time, the activated reed stems can also generate self-adhesion between fibers through thermal effect during the subsequent hot pressing process.

[0029] (3) Mix 250 parts water, 150 parts citric acid, 150 parts glucose, 50 parts tannic acid crosslinking agent, 2.8 parts p-toluenesulfonic acid catalyst and 9.8 parts melamine additive, and react in a one-pot method at 90°C for 3 hours. Then add 5.25 parts polyvinyl alcohol thickener. After the reaction temperature is cooled to 40°C, the product can be discharged to obtain a fully bio-based adhesive.

[0030] (4) Dilute the bio-based adhesive obtained in step (3) to a solid content of 15%, and then immerse the activated reed stems obtained in step (2) in the diluted bio-based adhesive. First, vacuum immerse for 10 minutes, and then immerse under pressure of 0.3 MPa for 30 minutes to allow the bio-based adhesive to adhere to the inside of the reed stems. Take out the immersed reed stems and drain them at room temperature. Dry the reed stems with the bio-based adhesive at 80°C until the moisture content is 10% to obtain the immersed reed stems.

[0031] (5) The impregnated reed stems obtained in step (4) are stacked and laid out along the fiber direction; then, a cold pressing process is used for pre-pressing, with a pressure of 20 MPa and a pressing time of 15 min; to prevent the board from bubbling, a segmented hot pressing process is used for curing, specifically: hot pressing at 190℃ and 4.5 MPa for 5 min, and then hot pressing at 3.5 MPa for 5 min; a reconstituted reed-based artificial board based on a fully bio-based adhesive is obtained. The thickness of this reconstituted reed-based artificial board based on a fully bio-based adhesive is 8 mm, and its density is 0.98 g / cm³. 3 .

[0032] Because the reconstituted reed-based engineered wood panels based on all-biomass-based adhesives have a high density, adhesive extrusion still occurs during the panel laying and compression process. If segmented hot pressing is used directly, demolding becomes difficult. Therefore, this invention employs a process of cold pressing followed by segmented hot pressing, which achieves rapid curing and molding of the reconstituted reed-based engineered wood panels based on all-biomass-based adhesives, thereby improving the efficiency of curing and molding.

[0033] Example 2:

[0034] A method for preparing a recombinant reed-based engineered wood panel based on a fully bio-based adhesive according to the present invention includes the following steps:

[0035] (1) Remove the leaves and flowers from the reed stems and use a high-pressure water gun to remove the mud, sand and other impurities from the surface of the reed stems. Then, use an electric roller press to spread the fibers radially to increase the contact area with the alkaline solution. After that, dry them to a moisture content of 5% and cut them into lengths of 420-450mm for subsequent laying, thus obtaining the treated reed stems.

[0036] (2) The treated reed stems obtained in step (1) are uniformly wetted with sodium hydroxide solution, and then dried at 103°C until the moisture content is 2.3% to obtain activated reed stems. The mass ratio of sodium hydroxide solution to treated reed stems is 15:100, and the mass percentage concentration of sodium hydroxide solution is 3%.

[0037] (3) Mix 400 parts water, 200 parts citric acid, 200 parts glucose, 75 parts tannic acid crosslinking agent, 3.0 parts p-toluenesulfonic acid catalyst, and 10.4 parts melamine additive, and react them in a one-pot method at 100°C for 3 hours. Then add 7.82 parts polyvinyl alcohol thickener. Once the reaction temperature is cooled to 40°C, the product can be discharged to obtain a fully bio-based adhesive.

[0038] (4) Dilute the bio-based adhesive obtained in step (3) to a solid content of 18%, and then immerse the activated reed stems obtained in step (2) in the diluted bio-based adhesive. First, vacuum immerse for 15 minutes, and then immerse under pressure of 0.4 MPa for 45 minutes to allow the bio-based adhesive to adhere to the inside of the reed stems. Take out the immersed reed stems and drain them at room temperature. Dry the reed stems with the bio-based adhesive at 80°C to a moisture content of 13% to obtain the immersed reed stems.

[0039] (5) The impregnated reed stems obtained in step (4) are stacked and laid out along the fiber direction; then, a cold pressing process is used for pre-pressing, with a pressure of 25 MPa and a pressing time of 20 min; to prevent the board from bubbling, a segmented hot pressing process is used for curing, specifically: hot pressing at 7.5 MPa for 9 min at a temperature of 180℃, and then hot pressing at 4.5 MPa for 6 min; thus, a reconstituted reed-based artificial board based on a fully bio-based adhesive is obtained. The thickness of this reconstituted reed-based artificial board based on a fully bio-based adhesive is 12 mm, and its density is 1.08 g / cm³. 3 .

[0040] Example 3:

[0041] A method for preparing a recombinant reed-based engineered wood panel based on a fully bio-based adhesive according to the present invention includes the following steps:

[0042] (1) Remove the leaves and flowers from the reed stems and use a high-pressure water gun to remove the mud, gravel and other impurities from the surface of the reed stems. Then, use an electric roller press to spread the fibers radially to increase the contact area with the alkaline solution. After that, dry them to a moisture content of 2% and cut them into lengths of 720-770mm for subsequent laying, thus obtaining the treated reed stems.

[0043] (2) The treated reed stems obtained in step (1) are uniformly wetted with sodium hydroxide solution, and then dried at 103°C to a moisture content of 3% to obtain activated reed stems. The mass ratio of sodium hydroxide solution to treated reed stems is 20:100, and the mass percentage concentration of sodium hydroxide solution is 3%.

[0044] (3) Mix 600 parts water, 200 parts citric acid, 200 parts glucose, 100 parts tannic acid crosslinking agent, 4.0 parts p-toluenesulfonic acid catalyst, and 12.6 parts melamine additive, and react them in a one-pot method at 110°C for 3 hours. Then add 10.25 parts polyvinyl alcohol thickener. Once the reaction temperature is cooled to 40°C, the product can be discharged to obtain a fully bio-based adhesive.

[0045] (4) Dilute the bio-based adhesive obtained in step (3) to a solid content of 20%, and then immerse the activated reed stems obtained in step (2) in the diluted bio-based adhesive. First, vacuum immerse for 20 minutes, and then immerse under pressure of 0.5 MPa for 60 minutes to allow the bio-based adhesive to adhere to the inside of the reed stems. Take out the immersed reed stems and drain them at room temperature. Dry the reed stems with the bio-based adhesive at 80°C to a moisture content of 15% to obtain the immersed reed stems.

[0046] (5) The impregnated reed stems obtained in step (4) are stacked and laid out along the fiber direction; then, a cold pressing process is used for pre-pressing, with a pressure of 30 MPa and a pressing time of 30 min; to prevent the board from bubbling, a segmented hot pressing process is used for curing, specifically: hot pressing at 180℃ and 9.5 MPa for 12 min, and then hot pressing at 5.5 MPa for 8 min; a reconstituted reed-based artificial board based on a fully bio-based adhesive is obtained. The thickness of this reconstituted reed-based artificial board based on a fully bio-based adhesive is 15 mm, and its density is 1.13 g / cm³. 3 .

[0047] Compared with organic reed boards prepared by existing methods, the recombinant reed-based engineered wood panel based on a fully bio-based adhesive in this embodiment exhibits superior flexural strength, dimensional stability, and ignition time. Figures 1-2 As shown in Table 1.

[0048] Table 1. Comparison of ignition times for reed-based engineered wood panels prepared by different methods.

[0049] Ignition time / s 42 57 63 64

[0050] Combination Figures 1-2As shown in Table 1, compared with existing organic reed boards, the recombinant reed-based artificial board based on fully bio-based adhesive of the present invention has significantly improved bending strength, better dimensional stability, and is less prone to complete combustion.

[0051] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention using the methods and techniques disclosed above, or modify them into equivalent embodiments with equivalent changes, without departing from the spirit and technical essence of the present invention. Therefore, any simple modifications, equivalent substitutions, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall still fall within the protection scope of the technical solutions of the present invention.

Claims

1. A method for preparing recombinant reed-based engineered wood panels based on a fully bio-based adhesive, characterized in that, Includes the following steps: S1. The reed stems are pretreated with an alkaline solution and then dried to obtain pretreated reed stems with a moisture content of 1% to 3%. S2. Citric acid, glucose, tannic acid, p-toluenesulfonic acid, melamine and water are mixed and reacted. Polyvinyl alcohol is added to obtain a fully bio-based adhesive. The reaction temperature is 90℃~110℃. S3. The pretreated reed stems obtained in step S1 are immersed in the all-bio-based adhesive obtained in step S2, and after draining and drying, the immersed reed stems are obtained. S4. The impregnated reed stems obtained in step S3 are stacked and laid out along the fiber direction, and then subjected to cold pressing and hot pressing treatments in sequence to obtain a reconstituted reed-based engineered wood panel based on a fully bio-based adhesive; the density of the reconstituted reed-based engineered wood panel based on the fully bio-based adhesive is 0.95 g / cm³. 3 ~1.13g / cm 3 ; In step S2, the amounts of each raw material required for preparing the fully bio-based adhesive are as follows (by weight): citric acid 150-200 parts, glucose 150-200 parts, tannic acid 50-100 parts, p-toluenesulfonic acid 2.8-4.0 parts, melamine 9.8-12.6 parts, water 250-600 parts, and polyvinyl alcohol 5.25-10.25 parts. In step S1, the mass percentage concentration of the alkaline solution is 2.5% to 3.5%, and the alkaline solution is at least one of sodium hydroxide solution, potassium hydroxide solution, calcium oxide solution, and sodium carbonate solution; the mass ratio of the alkaline solution to the reed stem is 10 to 20: 100 to 120. In step S4, the pressure of the cold pressing treatment is 20MPa to 35MPa, and the time of the cold pressing treatment is 15min to 30min; the hot pressing treatment is segmented hot pressing, and the specific process of the segmented hot pressing is as follows: at a temperature of 160℃ to 200℃, hot pressing is performed at 4.5MPa to 9.5MPa for 5min to 12min, and then hot pressing is performed at 3.5MPa to 6.5MPa for 5min to 8min.

2. The method for preparing recombinant reed-based engineered wood panels based on a fully bio-based adhesive according to claim 1, characterized in that, In step S2, the reaction time is 2.5h to 3.5h.

3. The method for preparing recombinant reed-based engineered wood panels based on a fully bio-based adhesive according to claim 1, characterized in that, In step S3, the specific process of impregnation is as follows: vacuum impregnation and pressure impregnation are performed sequentially; the vacuum impregnation time is 10 min to 20 min, the pressure impregnation time is 30 min to 60 min, and the pressure of pressure impregnation is 0.3 MPa to 0.5 MPa.

4. The method for preparing reconstituted reed-based engineered wood panels based on a fully bio-based adhesive according to claim 1, characterized in that, In step S1, the reed stems are further treated as follows before use: removing the reed leaves and flowers from the reed stems, washing the surface of the reed stems, and then rolling the reed stems to dry them to a moisture content of 2% to 8%; the washing is done with water, and the rolling is done with an electric roller press; the specific process of the pretreatment is: wetting the reed stems with an alkaline solution; the drying temperature is 95℃ to 105℃.

5. The method for preparing reconstituted reed-based engineered wood panels based on a fully bio-based adhesive according to claim 1, characterized in that, In step S3, the fully bio-based adhesive further includes the following treatment before use: diluting the fully bio-based adhesive obtained in step S2 to a solid content of 15% to 20%; the drying temperature is 50℃ to 80℃; and the moisture content of the reed stems after soaking is 10% to 15%.

6. A recombinant reed-based engineered wood panel based on a fully bio-based adhesive, prepared by any one of claims 1 to 5.

7. The recombinant reed-based engineered wood panel based on a fully bio-based adhesive according to claim 6, characterized in that, The thickness of the recombinant reed-based engineered wood panel based on the fully bio-based adhesive is 8mm to 15mm.

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