Formaldehyde-free moisture-proof medium-and-high-density straw artificial board and preparation method thereof

Abstract

The invention discloses a formaldehyde-free moisture-proof medium-and-high-density straw artificial board and a preparation method thereof, and relates to the technical field of artificial boards. The wood board is prepared from the following raw materials in parts by weight: 40-60 parts of a straw raw material, 15-30 parts of a wood raw material, 8-15 parts of an adhesive, 0.5-2 parts of a coupling agent, 2-4 parts of a nano waterproof coating and 1.5-5 parts of a wood board additive. The coupling agent is added into the straw fibers and the wood fibers, the fibers are modified through the coupling agent, and the strength of the straw artificial board is improved by enhancing the bonding stability of the fibers and the adhesive. The waterproof and moisture-proof performance of the straw artificial board is enhanced by spraying the nanometer waterproof coating and adding the waterproof agent. And the formaldehyde-free raw material is used to ensure that the straw artificial board meets the formaldehyde-free emission requirement. The straw artificial board has the advantages of no formaldehyde, moisture resistance and high strength.

Description

Technical Field

[0001] The present invention relates to the technical field of wood-based panels, and particularly to a manufacturing method of a formaldehyde-free moisture-proof medium and high density straw wood-based panel. Background Art

[0002] With the rapid development of the economy, the demand for wood boards in industries such as construction and decoration is increasing. However, the forest area in China is limited, and the wood raw materials provided by forests alone far cannot meet the social demand. China is a large agricultural country, and a large amount of crop straw is generated every year, with a total amount exceeding 1 billion tons. How to efficiently utilize crop straw resources to prepare wood-based panels that can be used in industries such as construction and decoration has very important value and research significance.

[0003] The patent document with the patent number CN113429584B named "A Wear-resistant Wheat Straw Composite Board and Its Preparation Method" discloses a process for preparing modified wheat straw by subjecting wheat straw powder to alkali treatment and acylation reaction, and finally obtaining a wear-resistant wheat straw composite board by hot pressing. This process improves the wear resistance of wood-based panels. However, in the actual application process of this method, reactions such as acylation, esterification, and compounding are required, the operation process is complex, and the reaction degree is not easy to control. At the same time, the problem of formaldehyde volatilization and waterproof and anti-corrosion performance of straw composite boards is not considered in the preparation process of this wear-resistant straw composite board. The straw composite board without adding a waterproof agent is easy to absorb water and expand in a humid environment, resulting in a decrease in the strength and wear resistance of the composite board, which limits the use environment of straw composite boards. Summary of the Invention

[0004] Aiming at the problems of excessive formaldehyde content, insufficient waterproof performance, and low strength existing in current straw wood-based panels, the present invention provides a formaldehyde-free moisture-proof medium and high density straw wood-based panel with relatively high strength and good waterproof performance and its manufacturing method.

[0005] The specific technical solution of the present invention is: A formaldehyde-free moisture-proof medium and high density straw wood-based panel is made from the following raw materials in parts by weight: 40 - 60 parts of straw raw materials, 15 - 30 parts of wood raw materials, 8 - 15 parts of adhesives, 0.5 - 2 parts of coupling agents, 2 - 4 parts of nano waterproof coatings, and 1.5 - 5 parts of wood board additives.

[0006] Preferably, the straw raw material is one or more of wheat straw, rice straw, corn straw, or cotton straw.

[0007] The above-mentioned straw has a large yield. Wheat straw has relatively long fibers and good toughness, which is suitable for manufacturing medium density wood-based panels. Rice straw has a low ash content in fibers, which is beneficial to improving the gluing performance of the board. Corn and cotton straw fibers have excellent mechanical properties and are suitable for manufacturing high-strength boards. By mixing the above various straws, wood-based panels with different properties can be manufactured according to needs.

[0008] Preferably, the wood raw material is one or more of poplar, pine, and eucalyptus.

[0009] Poplar has medium fiber length, soft fibers, and good processing performance; pine has longer fibers and high strength, suitable for manufacturing high-strength boards; eucalyptus has shorter fibers, higher hardness and density, and is suitable for manufacturing high-density boards.

[0010] Preferably, the adhesive is one or more of isocyanate (MDI), bio-based adhesive, thermoplastic resin adhesive, polyurethane adhesive, polyvinyl alcohol adhesive, and Simoda hard adhesive.

[0011] Since the adhesive is one of the main sources of formaldehyde in wood-based panels, the above various adhesives are formaldehyde-free adhesives with excellent environmental protection performance and can be used in the manufacture of formaldehyde-free wood-based panels.

[0012] Preferably, the coupling agent is one or more of silane coupling agent, titanate coupling agent, and aluminate coupling agent.

[0013] The coupling agent can connect fibers and adhesives through chemical bonds, significantly improving the mechanical properties of the board; reducing the damage of moisture to the interface between fibers and adhesives, improving the water resistance of the board; enhancing the bonding stability between fibers and adhesives, and extending the service life of the board.

[0014] Preferably, the nano waterproof coating is one or more of nano silica and nano zinc oxide.

[0015] The nano coating has superhydrophobic properties and can form a waterproof surface similar to the "lotus leaf effect" on the surface of wood-based panels, which can significantly improve the waterproof performance of straw wood-based panels.

[0016] Preferably, the waterproof agent is one or more of paraffin emulsion waterproof agent, polymer waterproof powder, water-soluble environmental protection waterproof agent, modified resin waterproof agent, and composite waterproof agent.

[0017] The above waterproof agents can all better improve the waterproof performance of wood-based panels, and are environmentally friendly, non-toxic, and have excellent comprehensive performance.

[0018] Preferably, the preservative is one or more of borate inorganic preservative, copper-based inorganic preservative, and quaternary ammonium salt organic preservative.

[0019] The above preservatives have the characteristics of low toxicity and broad-spectrum antibacterial, have a good inhibitory effect on bacteria and fungi, and have good environmental protection performance.

[0020] The present invention provides a method for manufacturing a formaldehyde-free moisture-proof medium and high-density straw wood-based panel, comprising the following steps: (1) Crush the straw raw materials and wood raw materials, remove impurities after screening, remove the waxy layer through the waxy layer treatment technology and dry. (2) Spray the coupling agent on the surface of the fiber, add additives and dry. (3) Spray the adhesive on the surface of the fiber. (4) Initially shape the fiber on a forming machine, and then respectively make a single-layer straw board and a wood-reinforced board through hot pressing. (5) Apply glue on both sides of the wood-reinforced board, stack it with two single-layer straw boards to form a three-layer composite board, then through pre-pressing and hot pressing, and finally after sanding, spray a nano waterproof layer and dry.

[0021] Advantages of the present invention:

[0022] The main raw material of the present invention is plant straw, with sufficient raw material supply and no pollution to the environment. Each component does not contain formaldehyde, reducing the generation of formaldehyde at the source. By adding a waterproof agent and spraying a waterproof coating on the surface of the board, the waterproof and moisture-proof performance of the board is significantly enhanced. The straw fibers are tightly bonded together through the adhesive, improving the strength of the board. Through the modification treatment of the surface of the straw fibers by the coupling agent, the interfacial bonding between the straw fibers and the adhesive is enhanced. The combined action of the adhesive and the coupling agent significantly improves the strength of the straw-based artificial board.

[0023] The formaldehyde-free moisture-proof medium-density straw-based artificial board of the present invention has high strength, a simple manufacturing method, simple and easily available raw materials, and excellent performance. Specific embodiments

[0024] In order to better illustrate the technical effects of the present invention, the following specific examples and comparative examples are analyzed.

[0025] General example:

[0026] A formaldehyde-free moisture-proof medium-density straw-based artificial board is made from the following raw materials in parts by weight: 40 - 60 parts of straw raw materials, 15 - 30 parts of wood raw materials, 8 - 15 parts of adhesive, 0.5 - 2 parts of coupling agent, 2 - 4 parts of nano waterproof coating, and 1.5 - 5 parts of board additive.

[0027] The straw raw materials are one or more of wheat straw, rice straw, corn straw, or cotton straw.

[0028] The wood raw materials are one or more of poplar, pine, or eucalyptus.

[0029] The adhesive is one or more of isocyanate (MDI), bio-based adhesive, thermoplastic resin adhesive, polyurethane adhesive, polyvinyl alcohol adhesive, or Shimadzu hard adhesive.

[0030] The coupling agent is one or more of silane coupling agents, titanate coupling agents, and aluminate coupling agents.

[0031] The nano waterproof coating is one or more of nano silicon dioxide and nano zinc oxide.

[0032] The additive is a waterproof agent and a preservative.

[0033] The waterproof agent is one or more of paraffin emulsion waterproof agents, polymer waterproof powders, water-soluble environmental protection waterproof agents, modified resin waterproof agents, and composite waterproof agents.

[0034] The preservative is one or more of borate inorganic preservatives, copper-based inorganic preservatives, and quaternary ammonium salt organic preservatives.

[0035] A manufacturing method of the above-mentioned formaldehyde-free moisture-proof medium-density straw-based artificial board comprises the following steps: (1) Crush the straw raw material and the wood raw material, remove impurities after screening, so that the lengths of the obtained straw fibers and wood fibers are both less than 10 mm. Immerse the straw fibers and wood fibers in a 5% sodium hydroxide solution at 50 °C for 1 h, and stir well during the immersion. Then take out the straw fibers and wood fibers and dry them; (2) Dissolve the coupling agent in ethanol to prepare a 5% solution, evenly spray the coupling agent solution on the surfaces of the straw fibers and wood fibers, and add a waterproof agent and a preservative; (3) Evenly spray the adhesive on the surfaces of the straw fibers and wood fibers; (4) Evenly pave the sized straw fibers and wood fibers on a molding machine respectively to form a 5-mm fiber layer, and pre-press the paved fiber layer for preliminary shaping. Send the pre-pressed fiber layer into a hot press, and hot press it for 5 min at 160-180 °C and 2.5-3.5 MPa to form a single-layer straw board and a wood reinforcement board. (5) Apply glue on both sides of the wood reinforcement board, stack it with two single-layer straw boards to form a three-layer composite board, then hot press it for 15 min at 160-180 °C and 2.5-3.5 MPa to form a shape. Then dissolve the nano-coating material in ethanol to prepare a 5% solution, spray the prepared solution on the surface of the sanded composite board and dry it to obtain the final product.

[0036] Example 1

[0037] A formaldehyde-free moisture-proof medium-density straw-based artificial board is made from the following raw materials in parts by weight: 50 parts of wheat straw, 22.5 parts of pine wood, 11.5 parts of isocyanate, 1.5 parts of silane coupling agent, 3 parts of nano waterproof coating, 2 parts of paraffin emulsion waterproof agent, and 1.5 parts of borate inorganic preservative.

[0038] Manufacture an aldehyde-free moisture-proof medium and high density straw-based artificial board through the following steps: (1) Crush wheat straw and pine wood, remove impurities after screening, so that the lengths of the obtained wheat straw fibers and pine wood fibers are both less than 10 mm. Immerse the wheat straw fibers and pine wood fibers in a 5% sodium hydroxide solution at 50 °C for 1 h, and stir well during immersion. Then take out the wheat straw fibers and pine wood fibers and dry them; (2) Dissolve the silane coupling agent in ethanol to prepare a 5% solution, evenly spray the silane coupling agent solution on the surfaces of the wheat straw fibers and pine wood fibers, and add paraffin emulsion waterproofing agent and borate inorganic preservative; (3) Evenly spray the isocyanate adhesive on the surfaces of the wheat straw fibers and pine wood fibers; (4) Evenly pave the sized wheat straw fibers and pine wood fibers on a forming machine respectively to form a 5-mm fiber layer, and pre-press the paved fiber layer for preliminary shaping. Send the pre-pressed fiber layer into a hot press, and hot press it at 160 °C and 3 MPa for 5 min to form a single-layer wheat straw board and a pine wood reinforced board. (5) Apply glue on both sides of the pine wood reinforced board, laminate it with two single-layer wheat straw boards to form a three-layer composite board, and then hot press it at 180 °C and 3.5 MPa for 15 min to form.

[0039] Example 2

[0040] An aldehyde-free moisture-proof medium and high density straw-based artificial board is made from the following raw materials in parts by weight: 40 parts of wheat straw, 15 parts of pine wood, 8 parts of isocyanate, 0.5 part of silane coupling agent, 2 parts of nano waterproof coating, 1 part of paraffin emulsion waterproofing agent, and 0.5 part of borate inorganic preservative.

[0041] Manufacture an aldehyde-free moisture-proof medium and high density straw-based artificial board through the following steps: (1) Crush wheat straw and pine wood, remove impurities after screening, so that the lengths of the obtained wheat straw fibers and pine wood fibers are both less than 10 mm. Immerse the wheat straw fibers and pine wood fibers in a 5% sodium hydroxide solution at 50 °C for 1 h, and stir well during immersion. Then take out the wheat straw fibers and pine wood fibers and dry them; (2) Dissolve the silane coupling agent in ethanol to prepare a 5% solution, evenly spray the silane coupling agent solution on the surfaces of the wheat straw fibers and pine wood fibers, and add paraffin emulsion waterproofing agent and borate inorganic preservative; (3) Evenly spray the isocyanate adhesive on the surfaces of the wheat straw fibers and pine wood fibers; (4) The sized wheat straw fibers and pine fibers are respectively evenly paved on a forming machine to form a 5-mm fiber layer. The paved fiber layer is pre-pressed for initial shaping. The pre-pressed fiber layer is fed into a hot press and hot-pressed at 160 °C and 3 MPa for 5 minutes to form a single-layer wheat straw board and a pine wood reinforced board. (5) Glue is applied to both sides of the pine wood reinforced board, and it is laminated with two single-layer wheat straw boards to form a three-layer composite board. Then it is hot-pressed at 180 °C and 3.5 MPa for 15 minutes to form. Then the nano-coating material is dissolved in ethanol to prepare a 5% solution, and the prepared solution is sprayed on the surface of the sanded composite board and dried to obtain the final product.

[0042] Example 3

[0043] An aldehyde-free moisture-proof medium- and high-density straw-based artificial board is made from the following raw materials in parts by weight: 60 parts of wheat straw, 30 parts of pine wood, 15 parts of isocyanate, 2 parts of silane coupling agent, 4 parts of nano waterproof coating, 3 parts of paraffin emulsion waterproof agent, and 2 parts of borate inorganic preservative.

[0044] The aldehyde-free moisture-proof medium- and high-density straw-based artificial board is manufactured through the following steps: (1) The wheat straw and pine wood are crushed, and impurities are removed after screening, so that the lengths of the obtained wheat straw fibers and pine fibers are both less than 10 mm. The wheat straw fibers and pine fibers are soaked in a 5% sodium hydroxide solution at 50 °C for 1 hour, and stirred well during soaking. Then the wheat straw fibers and pine fibers are taken out and dried; (2) The silane coupling agent is dissolved in ethanol to prepare a 5% solution, and the silane coupling agent solution is evenly sprayed on the surfaces of the wheat straw fibers and pine fibers, and the paraffin emulsion waterproof agent and borate inorganic preservative are added; (3) The isocyanate adhesive is evenly sprayed on the surfaces of the wheat straw fibers and pine fibers; (4) The sized wheat straw fibers and pine fibers are respectively evenly paved on a forming machine to form a 5-mm fiber layer. The paved fiber layer is pre-pressed for initial shaping. The pre-pressed fiber layer is fed into a hot press and hot-pressed at 160 °C and 3 MPa for 5 minutes to form a single-layer wheat straw board and a pine wood reinforced board. (5) Glue is applied to both sides of the pine wood reinforced board, and it is laminated with two single-layer wheat straw boards to form a three-layer composite board. Then it is hot-pressed at 180 °C and 3.5 MPa for 15 minutes to form. Then the nano-coating material is dissolved in ethanol to prepare a 5% solution, and the prepared solution is sprayed on the surface of the sanded composite board and dried to obtain the final product.

[0045] Example 4

[0046] A formaldehyde - free moisture - proof medium - to - high - density straw - based artificial board is made from the following raw materials in parts by weight: 50 parts of wheat straw, 22.5 parts of pine wood, 11.5 parts of isocyanate, 3 parts of nano - waterproof coating, 2 parts of paraffin emulsion waterproofing agent, and 1.5 parts of borate inorganic preservative.

[0047] The formaldehyde - free moisture - proof medium - to - high - density straw - based artificial board is manufactured through the following steps: (1) Crush wheat straw and pine wood, remove impurities after screening, so that the lengths of the obtained wheat straw fibers and pine wood fibers are both less than 10 mm. Immerse the wheat straw fibers and pine wood fibers in a 5% sodium hydroxide solution at 50 °C for 1 h, and stir well during immersion. Then take out the wheat straw fibers and pine wood fibers and dry them; (2) Add paraffin emulsion waterproofing agent and borate inorganic preservative to the wheat straw fibers and pine wood fibers; (3) Evenly spray the isocyanate adhesive on the surfaces of the wheat straw fibers and pine wood fibers; (4) Evenly pave the sized wheat straw fibers and pine wood fibers on a forming machine respectively to form a 5 - mm fiber layer, and pre - press the paved fiber layer to achieve preliminary shaping. Send the pre - pressed fiber layer into a hot press, and hot - press it at 160 °C and 3 MPa for 5 min to form a single - layer wheat straw board and a pine wood - reinforced board. (5) Apply glue on both sides of the pine wood - reinforced board, stack it with two single - layer wheat straw boards to form a three - layer composite board, and then hot - press it at 180 °C and 3.5 MPa for 15 min to form. Then dissolve the nano - coating material in ethanol to prepare a 5% solution, spray the prepared solution on the surface of the sanded composite board and dry it to obtain the final product.

[0048] Example 5

[0049] A formaldehyde - free moisture - proof medium - to - high - density straw - based artificial board is made from the following raw materials in parts by weight: 50 parts of wheat straw, 22.5 parts of pine wood, 11.5 parts of isocyanate, 1.5 parts of silane coupling agent, 3 parts of nano - waterproof coating, and 1.5 parts of borate inorganic preservative.

[0050] The formaldehyde - free moisture - proof medium - to - high - density straw - based artificial board is manufactured through the following steps: (1) Crush wheat straw and pine wood, remove impurities after screening, so that the lengths of the obtained wheat straw fibers and pine wood fibers are both less than 10 mm. Immerse the wheat straw fibers and pine wood fibers in a 5% sodium hydroxide solution at 50 °C for 1 h, and stir well during immersion. Then take out the wheat straw fibers and pine wood fibers and dry them; (2) Dissolve the silane coupling agent in ethanol to prepare a 5% solution, evenly spray the silane coupling agent solution on the surfaces of wheat straw fibers and pine wood fibers, and add borate inorganic preservatives. (3) Evenly spray the isocyanate adhesive on the surfaces of wheat straw fibers and pine wood fibers. (4) Respectively and evenly lay the sized wheat straw fibers and pine wood fibers on a forming machine to form a 5-mm fiber layer, pre-press the laid fiber layer to conduct preliminary shaping. Feed the pre-pressed fiber layer into a hot press, and hot press for 5 min under the conditions of 160 °C and 3 MPa to form a single-layer wheat straw board and a pine wood reinforced board. (5) Apply glue on both sides of the pine wood reinforced board, stack it with two single-layer wheat straw boards to form a three-layer composite board, then hot press for 15 min under the conditions of 180 °C and 3.5 MPa to form it, then dissolve the nano-coating material in ethanol to prepare a 5% solution, spray the prepared solution on the surface of the sanded composite board and dry it to obtain the final product.

[0051] Example 6

[0052] An aldehyde-free moisture-proof medium- and high-density straw-based artificial board is made from the following raw materials in parts by weight: 50 parts of wheat straw, 11.5 parts of isocyanate, 1.5 parts of silane coupling agent, 3 parts of nano waterproof coating, 2 parts of paraffin emulsion waterproofing agent, and 1.5 parts of borate inorganic preservative.

[0053] Manufacture the aldehyde-free moisture-proof medium- and high-density straw-based artificial board through the following steps: (1) Crush the wheat straw, remove impurities after screening to make the length of the obtained wheat straw fibers all less than 10 mm, soak the wheat straw fibers in a 5% sodium hydroxide solution at 50 °C for 1 h, and fully stir during soaking. Then take out the wheat straw fibers and dry them. (2) Dissolve the silane coupling agent in ethanol to prepare a 5% solution, evenly spray the silane coupling agent solution on the surface of the wheat straw fibers, and add paraffin emulsion waterproofing agent and borate inorganic preservatives. (3) Evenly spray the isocyanate adhesive on the surface of the wheat straw fibers. (4) Respectively and evenly lay the sized wheat straw fibers on a forming machine to form a 5-mm fiber layer, pre-press the laid fiber layer to conduct preliminary shaping. Feed the pre-pressed fiber layer into a hot press, and hot press for 5 min under the conditions of 160 °C and 3 MPa to form a single-layer wheat straw board. (5) Glue is applied to both sides of a single-layer wheat straw board, which is then laminated with another two single-layer wheat straw boards to form a three-layer composite board. Then, it is hot-pressed at 180 °C and 3.5 MPa for 15 minutes to form. Then, the nano-coating material is dissolved in ethanol to prepare a 5% solution, and the prepared solution is sprayed on the surface of the sanded composite board and dried to obtain the final product.

[0054] Comparative Example 1

[0055] This comparative example is a straw-based artificial board manufactured by a conventional process.

[0056] The performance tests of Examples 1-6 and Comparative Example 1 were all carried out in accordance with 《GB / T 17657-2013》. The specific test methods are as follows:

[0057] Moisture content test: (1) Weigh the initial mass of the specimen; (2) Place the specimen in an oven and dry it to a constant weight at 103 °C ± 2 °C; (3) Weigh the mass after drying; (4) Calculate the moisture content.

[0058] Modulus of rupture test: (1) Place the specimen on the supports and apply a concentrated load until the specimen breaks; (2) Record the maximum load and the specimen dimensions; (3) Calculate the modulus of rupture.

[0059] Elastic modulus test: (1) In the modulus of rupture test, record the load-deflection curve; (2) Calculate the elastic modulus.

[0060] Internal bond strength test: (1) Paste loading blocks on the upper and lower surfaces of the specimen; (2) Apply a tensile load until the specimen delaminates; (3) Calculate the internal bond strength.

[0061] Thickness swelling rate after water absorption test: (1) Measure the initial thickness of the specimen; (2) Immerse the specimen in water for 24 hours; (3) Measure the thickness after immersion; (4) Calculate the thickness swelling rate after water absorption.

[0062] Moisture-proof performance test: (1) Place the specimen in a constant temperature and humidity chamber at 20 °C and 65% humidity until the mass is constant; (2) Immerse the specimen in water at 20 °C, take it out, dry it, and then put it into a freezer at -12—-25 °C. After freezing, take it out and place it in a forced-air drying oven at 70 °C to dry and cool. (3) Repeat the operation in step (2) 2 times; (4) Place the specimen in a constant temperature and humidity chamber at 20 °C and 65% humidity until the mass is constant; (5) Determine the thickness swelling rate after water absorption after treatment.

[0063] Formaldehyde emission test: Testing the formaldehyde content by the perforation extraction method: After crushing the test piece, extract formaldehyde with toluene and determine the formaldehyde content by titration.

[0064] The performance test results are shown in Table 1

[0065] Table 1

[0066] Comparing the data of Examples 1-4, it can be seen that the coupling agent has a significant impact on the strength of straw-based panels. This is because the coupling agent is a compound with bifunctional groups. The inorganic-philic end of the coupling agent can react with the active groups on the fiber surface, while the organic-philic end can react with the active groups in the matrix material. This can greatly enhance the interfacial bonding force between the fiber and the adhesive, and at the same time improve the mechanical properties and water resistance of the panel. After the moisture-proof performance test, the 24-hour water absorption thickness swelling rate of Examples 1-3 with the coupling agent added is lower and changes less than that of Example 4, indicating that the coupling agent has a greater impact on the moisture-proof performance of straw-based panels.

[0067] Comparing the data of Examples 1-3 and Example 5, it can be seen that the 24-hour water absorption thickness swelling rate of the straw-based panel in Example 5 without the waterproof agent added is significantly higher than that of Examples 1-3, which has a greater impact on the moisture-proof performance of the straw-based panel.

[0068] Comparing the data of Examples 1-3 and Example 6, it can be seen that the strength of the single-layer straw-based panel is significantly lower than that of the composite straw-based panel containing wood reinforcement plates in Examples 1-3.

[0069] Comparing the data of Examples 1-3 and Comparative Example 1, it can be seen that the straw-based panel of the present invention is significantly stronger than the general straw-based panel in terms of strength and moisture-proof performance, and the straw-based panel of the present invention does not release formaldehyde and is safer and more environmentally friendly.

[0070] The raw materials and equipment used in the present invention are all common raw materials and equipment in the art without special instructions; the methods used in the present invention are all conventional methods in the art without special instructions.

[0071] The above are only the preferred embodiments of the present invention, and do not limit the present invention in any way. Any simple modification, change, and equivalent transformation made to the above embodiments according to the technical essence of the present invention still belong to the protection scope of the technical solution of the present invention.

Claims

1. A formaldehyde-free moisture-proof medium- and high-density straw-based panel, characterized in that: The invention is prepared from the following raw materials in parts by weight: 40-60 parts of straw raw materials, 15-30 parts of wood raw materials, 8-15 parts of adhesives, 0.5-2 parts of coupling agents, 2-4 parts of nano waterproof coatings and 1.5-5 parts of wood board additives.

2. The formaldehyde-free moisture-proof medium- and high-density straw-based panel according to claim 1, characterized in that: The straw raw material is one or more of wheat straw, rice straw, corn straw or cotton straw.

3. The formaldehyde-free moisture-proof medium- and high-density straw-based panel according to claim 1, characterized in that: The wood raw material is one or more of poplar, pine and eucalyptus.

4. The formaldehyde-free moisture-proof medium- and high-density straw-based panel according to claim 1, characterized in that: The adhesive is one or more of isocyanate (MDI), bio-based adhesive, thermoplastic resin adhesive, polyurethane adhesive, polyvinyl alcohol adhesive, and schminized hard adhesive.

5. The formaldehyde-free moisture-proof medium- and high-density straw-based panel according to claim 1, characterized in that: The coupling agent is one or more of a silane coupling agent, a titanate coupling agent, and an aluminate coupling agent.

6. The formaldehyde-free moisture-proof medium- and high-density straw-based panel according to claim 1, characterized in that: The nano waterproof coating is one or more of nano silicon dioxide and nano zinc oxide.

7. The formaldehyde-free moisture-proof medium- and high-density straw-based panel according to any one of claims 1 to 6, characterized in that: The additives include 1-3 parts of waterproofing agent and 0.5-2 parts of preservative.

8. The formaldehyde-free moisture-proof medium- and high-density straw-based panel according to claim 7, characterized in that: The waterproofing agent is one or more of a paraffin emulsion waterproofing agent, a polymer waterproofing powder, a water-soluble environmentally friendly waterproofing agent, a modified resin waterproofing agent, and a composite waterproofing agent.

9. The formaldehyde-free moisture-proof medium- and high-density straw-based panel according to claim 7, characterized in that: The preservative is one or more of a borate inorganic preservative, a copper-based inorganic preservative, and a quaternary ammonium salt organic preservative.

10. A method for preparing the formaldehyde-free moisture-proof medium- and high-density straw-based artificial board according to claim 1, comprising the following steps: (1) crushing straw raw materials and wood raw materials, removing impurities after screening, removing the wax layer through wax layer treatment technology and drying; (2) Spray the coupling agent on the fiber surface, add additives and dry; (3) Spraying adhesive on the fiber surface; (4) preliminarily shaping the fibers on a molding machine, and then forming them into straw single-layer boards and wood reinforced boards respectively by hot pressing; (5) Glue is applied on both sides of the wood reinforcement board, and the board is overlapped with two single-layer straw boards to form a three-layer composite board, which is then formed by pre-pressing and hot pressing, and then sprayed with a nano waterproof layer after sanding and drying.

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