Preparation method for preparing fiberboard based on rice husks and application of fiberboard

Abstract

The invention discloses a preparation method for preparing a fiberboard based on rice hulls and application of the fiberboard. The rice hulls are deeply processed through a simple technological means, so that the rice hulls are converted into the fiberboard with higher economic value, recycling of the rice hulls can be achieved, greenhouse gas emission generated in the incineration process is reduced, and the production cost is reduced. A new means is provided for green and environment-friendly treatment of the rice husks. The density of the fiberboard prepared through the method reaches 0.015-0.03 g / cm < 3 >, the mechanical property is excellent, the compression strength of the fiberboard can reach 27 MPa or above, the standard performance of the fiberboard is very close to that of a traditional wood fiberboard, and the possibility is provided for replacing wood fiberboards prepared from trees needing to be cut down to be applied to furniture, buildings, packaging and other multiple purposes.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of deep processing of rice hulls, and in particular to a method for preparing fiberboard based on rice hulls and its application. BACKGROUND

[0002] Rice hulls account for about 20% of the weight of harvested rice and are an important agricultural byproduct, with global annual production exceeding 150 million tons. Traditionally, rice hulls are usually disposed of by open-air burning, which releases harmful pollutants into the atmosphere and exacerbates climate change. This not only leads to environmental degradation, but also poses a threat to the health of nearby communities. With increasing global attention on sustainable development and waste reduction, there is an urgent need to develop innovative solutions to handle agricultural residues like rice hulls. SUMMARY

[0003] Therefore, based on the above background, the present application provides a method for preparing fiberboard based on rice hulls and its application, which converts agricultural waste rice hulls into fiberboard, realizes the recycling and deep processing of rice hulls, improves their economic value, and provides a new means for the green and environmentally friendly disposal of rice hulls.

[0004] The technical scheme provided by the present application is as follows:

[0005] A method for preparing fiberboard based on rice hulls, comprising the following steps:

[0006] ① Pulverize the rice hulls and sieve them to obtain rice hull particles with a particle size of 0.015-0.3 μm;

[0007] ② Soak the rice hull particles obtained in step ① in an alkali solution for alkali treatment;

[0008] ③ Rinse the rice hulls after alkali treatment in step ② with water until the pH is 8 or below;

[0009] ④ Mix the rinsed rice hulls in step ③ with a binder solution, stir uniformly, and then hot-press to obtain the fiberboard.

[0010] Preferably, the alkali solution in step ② is a sodium hydroxide aqueous solution with a mass-volume ratio of 5-10% w / v.

[0011] Preferably, the binder solution in step ④ is a mixture of polyvinyl acetate and ethanol.

[0012] The ratio of polyvinyl acetate to ethanol (g / ml) is (12-16):(50-70).

[0013] Preferably, the mass ratio of rice hulls to polyvinyl acetate in step ④ is 30:(12-16).

[0014] Preferably, the hot pressing conditions in step ④ are:

[0015] The hot pressing pressure is 5–10 MPa; the hot pressing temperature is 150–200℃; and the hot pressing time is 10–30 minutes.

[0016] Preferably, in step ④, the mass ratio of rice husk to polyvinyl acetate is 30:(14-16), and the material-liquid ratio (g / ml) of polyvinyl acetate to ethanol is (14-16):(50-70).

[0017] The hot pressing pressure is (10-12) MPa; the hot pressing temperature is 230-235℃; and the hot pressing time is 5 min.

[0018] Based on the same inventive concept, the present invention also provides a fiberboard prepared by a method for preparing fiberboard based on rice husk.

[0019] Based on the same inventive concept, the present invention also provides the application of the fiberboard prepared by the present invention in any of the fields of furniture, construction and packaging.

[0020] Furthermore, the fiberboard can be used to prepare indoor furniture panels, kitchen and bathroom substrates, door panels, flooring substrates, wall and ceiling decorative substrates, or pressure-bearing / supporting cushioning packaging pads.

[0021] The beneficial effects achieved by this invention are as follows:

[0022] This invention utilizes simple processing methods to deeply process rice husks, transforming them into fiberboard with higher economic value. This enables the recycling and reuse of rice husks, reduces greenhouse gas emissions from incineration, and provides a new means for the green and environmentally friendly treatment of rice husks.

[0023] The fiberboard prepared by this invention has a density of 0.015–0.03 g / cm³. 3 It has excellent chemical properties, and its compressive strength can reach 27MPa and above, which is very close to the standard performance of traditional wood fiberboard. It provides the possibility for wood fiberboard that needs to be made from felled trees to be used in a variety of applications such as furniture, construction and packaging.

[0024] Furthermore, the present invention also has the following advantages:

[0025] Sustainable raw materials: Rice husks are widely available, renewable, and have a stable supply, reducing production costs and dependence on timber resources.

[0026] Environmentally friendly: It adopts a formaldehyde-free adhesive system and mild process, with low VOC emissions, promoting the high-value utilization of agricultural by-products.

[0027] Excellent load-bearing performance: It achieves high compressive strength and dimensional stability within a low-density range, meeting the requirements of pressure-bearing conditions such as furniture supports, ground base layers, and packaging cushioning.

[0028] The process is controllable: the adhesive ratio and hot pressing parameter window are clearly defined, and after optimization, they have good consistency and scale-up feasibility.

[0029] Wide applicability: It can be combined with water-repellent, flame-retardant, and decorative functional systems to form a series of products covering multiple application scenarios.

[0030] Instruction manual illustrations

[0031] Appendix Figure 1 The image shows rice husk raw material according to an embodiment of the present invention.

[0032] Appendix Figure 2 This is a picture of rice husks after screening, as shown in an embodiment of the present invention.

[0033] Appendix Figure 3 This is a diagram of the fiberboard prepared according to an embodiment of the present invention. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods; unless otherwise specified, the materials used in the following embodiments are all purchased from commercial channels.

[0036] The technical solution of the present invention:

[0037] A method for preparing fiberboard based on rice husks, comprising the following steps:

[0038] ① Crush the rice husks and sieve them to obtain rice husk particles with a particle size between 0.015 and 0.3 μm;

[0039] In this step, the rice husks are washed and dried before being crushed.

[0040] ② Soak the rice husk particles obtained in step ① in an alkaline solution for 8 hours to remove lignin and impurities;

[0041] In this step, the alkaline solution used is a sodium hydroxide aqueous solution with a mass-to-volume ratio of 5-10% w / v.

[0042] The purpose of this step is to utilize NaOH to effectively decompose lignin and hemicellulose, thereby enhancing fiber separation and improving adhesive properties.

[0043] ③ Rinse the rice husks treated with alkali in step ② with water until the pH is around 8;

[0044] This step is essential, and its main purpose is to remove residual sodium hydroxide from the rice husks to prevent adverse effects on the adhesive properties and to reduce the risk of skin irritation that the material may cause.

[0045] ④ After mixing the rice husks rinsed in step ③ with the adhesive solution, stir quickly and evenly, then hot press (hot pressing pressure is 5–10 MPa; hot pressing temperature is 150–200℃; hot pressing time is 10–30 minutes) to prepare fiberboard.

[0046] The adhesive solution in this step is made of polyvinyl acetate (PVAc) and 75% ethanol at a ratio (g / ml) of (12-16):(50-70).

[0047] The mass ratio of rice husks after alkali treatment and washing to polyvinyl acetate is 30:(12-16).

[0048] Compared to traditional adhesives (such as polypropylene or polyethylene), PVAc offers superior bonding performance, lower environmental impact, and good biodegradability. Specifically, the adhesive solution is prepared by dissolving polyvinyl acetate (PVAc) in 75% ethanol and heating and stirring at 80°C.

[0049] Example: A method for preparing fiberboard based on rice husks, comprising the following steps:

[0050] A method for preparing fiberboard based on rice husks, comprising the following steps:

[0051] ① Take rice husks, wash and dry them (see attached document). Figure 1 The rice husks are then crushed and sieved to obtain rice husk particles with a particle size between 0.015 and 0.3 μm; see attached image. Figure 2 As shown.

[0052] In this step, the rice husks are washed and dried before being crushed.

[0053] ② Soak the rice husk particles obtained in step ① in an alkaline solution for 8 hours to remove lignin and impurities;

[0054] In this step, a sodium hydroxide aqueous solution with a mass-to-volume ratio of 10% w / v is used as the alkali solution.

[0055] ③ Rinse the rice husks treated with alkali in step ② with water until the pH is around 8;

[0056] This step is essential, and its main purpose is to remove residual sodium hydroxide from the rice husks to prevent adverse effects on the adhesive properties and to reduce the risk of skin irritation that the material may cause.

[0057] ④ After rinsing 300g of rice husks in step ③, mix them with the adhesive solution and stir quickly until uniform. Then, quickly put the mixture into a mold and hot press it (hot pressing pressure is 5MPa; hot pressing temperature is 150-200℃; hot pressing time is 10-30 minutes) to prepare fiberboard.

[0058] In this step, the adhesive solution is made of polyvinyl acetate (PVAc) (average molecular weight of 100,000) and 75% ethanol at a material-to-liquid ratio (g / ml) of (12-16):(50-70).

[0059] The mass ratio of rice husks after alkali treatment and washing to polyvinyl acetate is 30:(12-16).

[0060] Appropriate temperature is crucial for the thermal activation of the adhesive, promoting polymer flow and ensuring optimal bonding between fibers. Too low a temperature may fail to provide sufficient bonding strength, while too high a temperature may lead to degradation of the adhesive or fibers, affecting the performance of the prepared fiberboard. Therefore, as shown in Table 1, this example mixed 300g of rice husks treated with alkali and rinsed with water with adhesive solutions prepared from PVAc and 75% ethanol in different proportions, and set different hot-pressing conditions to prepare different fiberboards. The density of the fiberboards and its key indicator, compressive strength, were then tested. The compressive strength was determined according to the compression performance test method in GB / T 17657. Specifically, the samples were tested after conditioning at 20±2℃ and a relative humidity of 65±5%.

[0061] Table 1: Fiberboard prepared under different preparation conditions and its compressive strength

[0062]

[0063]

[0064] As can be seen from the table above, when 300g of treated rice husks is mixed with an adhesive solution prepared with 140-160g of PVAc and 500-700ml of 75% ethanol, and hot-pressed at a pressure of 10-15MPa, a temperature of 230-250℃, and a time of 5min, the resulting fiberboard exhibits a compressive strength of 27MPa or higher. Figure 3 This is product number 41.

[0065] The present invention and its embodiments have been described above. This description is not restrictive, and the embodiments shown are only one of the embodiments of the present invention. The actual structure is not limited to this. In conclusion, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the present invention, they should all fall within the protection scope of the present invention.

Claims

1. A method for preparing fiberboard based on rice husks, characterized in that, It includes the following steps: ① Crush the rice husks and sieve them to obtain rice husk particles with a particle size between 0.015 and 0.3 μm; ② Soak the rice husk particles obtained in step ① in an alkaline solution for alkaline treatment; ③ Rinse the rice husks treated with alkali in step ② with water until the pH is 8 or below; ④ After mixing the rice husks rinsed in step ③ with the adhesive solution and stirring evenly, hot pressing is performed to prepare fiberboard.

2. The method for preparing fiberboard based on rice husks according to claim 1, characterized in that, The alkaline solution used in step ② is a sodium hydroxide aqueous solution with a mass-to-volume ratio of 5-10% w / v.

3. The method for preparing fiberboard based on rice husks according to claim 1, characterized in that, The adhesive solution in step ④ is prepared by mixing polyvinyl acetate and anhydrous ethanol; The ratio (g / ml) of polyvinyl acetate to ethanol is (12-16):(50-70).

4. The method for preparing fiberboard based on rice husks according to claim 2, characterized in that, The mass ratio of rice husk to polyvinyl acetate in step ④ is 30:(12-16).

5. The method for preparing fiberboard based on rice husks according to claim 4, characterized in that, The conditions for hot pressing in step ④ are: The hot pressing pressure is 5–10 MPa; the hot pressing temperature is 150–200℃; and the hot pressing time is 10–30 minutes.

6. The method for preparing fiberboard based on rice husks according to claim 4, characterized in that, The mass ratio of rice husk to polyvinyl acetate in step ④ is 30:(14-16), and the material-liquid ratio (g / ml) of polyvinyl acetate to ethanol is (14-16):(50-70). The hot pressing pressure is (10-12) MPa; the hot pressing temperature is 230-235℃; and the hot pressing time is 5 min.

7. The fiberboard prepared by the method for preparing fiberboard based on rice husks as described in any one of claims 1 to 6.

8. The use of the fiberboard of claim 7 in any of the fields of furniture, construction and packaging.

9. The application according to claim 8, characterized in that, The fiberboard can be used to prepare indoor furniture panels, kitchen and bathroom substrates, door panels, flooring substrates, wall and ceiling decorative substrates, or pressure-bearing / supporting cushioning packaging pads.

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