Wood activating agent, preparation method thereof and method for preparing formaldehyde-free artificial board by using activating agent

Abstract

The invention relates to the field of wood processing, and particularly discloses a wood activating agent, a preparation method thereof and a method for preparing a formaldehyde-free artificial board by using the activating agent. The activating agent is prepared from the following raw materials in percentage by weight: 60%-80% of a polyol solution, 10%-30% of a viscosity modifier and 10% of an auxiliary agent; the preparation method comprises the following steps: uniformly mixing the polyhydric alcohol solution, the viscosity modifier and the auxiliary agent with certain concentration and proportion, and carrying out chemical crosslinking and physical combination to obtain the wood activator with stable performance; after wood veneers, wood shavings and fibers are treated by the wood activating agent disclosed by the invention, formaldehyde-free plywood, shaving boards and fiberboards are prepared under a high-temperature hot-pressing condition. The method has the advantages of economy, high efficiency, convenience and the like, and a new thought is provided for formaldehyde-free artificial board production.

Description

Technical Field

[0001] The invention belongs to the field of wood processing, relates to a wood activator and a preparation method thereof, and particularly relates to a method for preparing formaldehyde-free plywood, particleboard and fiberboard by activating the wood activator. Background Art

[0002] With the increasing scarcity of forest resources and growing awareness of ecological and environmental protection, the wood processing industry faces multiple challenges, including increasing difficulty in obtaining raw materials and the urgent need to improve resource utilization efficiency. As an engineering material that efficiently utilizes wood, wood-based panels play a vital role in alleviating the imbalance between wood supply and demand and improving resource utilization. In particular, their stable structure and excellent performance have led to their widespread application in construction, furniture, transportation, and other fields.

[0003] The production of traditional wood-based panels primarily relies on synthetic adhesives derived from petrochemical sources, such as urea-formaldehyde resins, phenol-formaldehyde resins, and melamine-formaldehyde resins. These adhesives offer high bond strength and excellent durability, but are generally subject to formaldehyde emissions. Formaldehyde, a volatile organic compound, can cause indoor air pollution and even harm human health if released over a long period of time. As the environmental shortcomings of traditional wood-based panels become increasingly apparent, the development of formaldehyde-free, low-carbon, and renewable adhesive technologies has become a key area of ​​technological advancement for the industry.

[0004] Common formaldehyde-free gluing technologies include the use of natural polymers such as soy protein, tannin, lignin, etc. to prepare bio-based adhesives to achieve low-toxicity or even zero formaldehyde release. On this basis, the exploration of glue-free gluing technology, that is, not relying on external adhesives, achieving effective gluing through the regulation of the wood's own structure and composition, breaking through the dependence on external adhesives, has become a current research hotspot. Among them, the development of wood activators has become the key. By introducing natural or low-toxic modifiers (such as polyols, plant extracts, etc.), the wood is given a certain degree of reactivity and adhesion, thereby achieving physical and chemical connections between wood molecules during the hot pressing process. This type of method can not only reduce the amount of adhesive used, but also further reduce the risk of formaldehyde. Summary of the Invention

[0005] The main purpose of this invention is to develop a wood activator and provide a method for producing formaldehyde-free, environmentally friendly wood-based panels. The wood-based panels produced by this invention are environmentally friendly, economical, and have physical, mechanical, and water-resistant properties that meet national standards. They are widely applicable in furniture, building materials, decorative materials, and other fields. This method provides a new approach for the sustainable production of formaldehyde-free, environmentally friendly wood-based panels.

[0006] To achieve the above object, the present invention provides the following technical solution for preparing a wood activator:

[0007] Based on the total mass, take 60-80% of the polyol mixed solution and 10-30% of the viscosity regulator, stir evenly for 3-5 minutes, then add 10% of the additive, stir thoroughly for 5-8 minutes until there are no obvious particles in the system, and let it stand at room temperature for 5 minutes to obtain a stable wood activator.

[0008] Furthermore, the polyol mixed solution in the step includes one or more of polyvinyl alcohol, polyethylene glycol and glycerol solution, and is mixed in any proportion.

[0009] Furthermore, the viscosity regulator in the step includes one or more of soybean powder, peanut protein powder, walnut protein powder, flour and konjac fly starch, and is mixed in any proportion.

[0010] Furthermore, the auxiliary agent in the step includes one or more of vanillin, borax, and sodium formate, and they are mixed in any proportion.

[0011] The present invention provides a method for preparing formaldehyde-free plywood:

[0012] The prepared wood activator is evenly applied to the surface of the veneer, and the veneer blanks are assembled in a crisscross pattern according to the fiber direction. Subsequently, the assembled blanks are placed in a hot press and fully hot-pressed before being depressurized to obtain the formaldehyde-free plywood.

[0013] Furthermore, the wood activator is applied to the veneer and is evenly coated on both sides of the core board.

[0014] Furthermore, the coating amount of the wood activator is 100-200g / m 2 .

[0015] Furthermore, the wood veneers are arranged in a crisscross pattern according to the fiber direction, and the number of layers is 3-13.

[0016] Furthermore, the hot pressing temperature is 120-200° C., the hot pressing pressure is 0.8-1.6 MPa, and the hot pressing time is 15-60 min.

[0017] The present invention provides a method for preparing formaldehyde-free particleboard and fiberboard:

[0018] The prepared wood activator is evenly applied to the wood shavings and fibers, the prepared materials are evenly stirred, and the materials are laid out in sequence to form the materials. Subsequently, the materials are placed in a hot press and fully hot-pressed, and then the pressure is released to obtain the formaldehyde-free particleboard and fiberboard.

[0019] Furthermore, the moisture content of the wood shavings and fibers is 2-5%.

[0020] Furthermore, the amount of the wood activator applied is 5-12% of the total mass.

[0021] Furthermore, the hot pressing temperature is 160-250° C., the hot pressing pressure is 0.5-6 MPa, and the hot pressing time is 10-40 min.

[0022] Formaldehyde-free artificial boards prepared by any formula and preparation process parameters of the method of the present invention are also within the protection scope of the present invention.

[0023] The present invention improves wood activity through the synergistic effect of the activator, causing wood molecules to migrate and crosslink during the hot pressing process, forming a glue-free bonding interface between each veneer, wood shavings and fiber, thereby achieving efficient and high-strength wood bonding. In addition, through a large number of experiments, combined with its results, it was found that the application amount of the wood activator, hot pressing temperature, hot pressing time and hot pressing pressure are the key factors determining the bond strength of the formaldehyde-free artificial board. If the above-mentioned process parameters are too high or too low, the activator will not be able to enter the wood pore structure well, thereby affecting the degree of activation of the wood material and reducing the strength of the prepared artificial board.

[0024] By rationally controlling the above-mentioned process parameters, it is possible to prepare formaldehyde-free artificial boards with good mechanical properties and water resistance, and their strength can meet the use requirements of national standards. Therefore, the beneficial effect of the present invention is that by using an environmentally friendly wood activator to press the artificial board, not only is the preparation method simple and easy, but the raw materials are widely available and inexpensive, providing a new approach for the sustainable production of low-cost formaldehyde-free artificial boards. In addition, the method of the present invention has the advantages of safety and environmental protection, does not pose a threat to human health and the environment, and is of great significance for reducing environmental pollution, alleviating environmental pressure, and improving the utilization rate of biomass resources. DETAILED DESCRIPTION

[0025] In order to better illustrate the technical features of the present invention, the following are some embodiments based on the content of the present invention, which further explain the technical solutions of the present invention, but should not be understood as limiting the present invention.

[0026] Example 1

[0027] A preparation method of a wood activator:

[0028] 1. First, take 25g of polyvinyl alcohol, 25g of polyethylene glycol, and 20g of glycerol solution and mix them evenly as the base solvent. Then add 10g of soy flour, 5g of walnut flour, and 5g of peanut flour. Stir evenly at room temperature for 5 minutes to ensure that the plant protein is fully dispersed and dissolved in the polyol system.

[0029] 2. To the above mixture, 6 g of vanillin and 3 g of sodium formate were added as additives, followed by 1 g of borax. The mixture was stirred for 8 minutes until the mixture was uniform with no obvious solid particles or flocs, forming a homogeneous liquid. This was the prepared wood activator.

[0030] Example 2

[0031] A method for preparing three-layer formaldehyde-free environmentally friendly plywood:

[0032] 1. Take three sheets of 1.8mm thick poplar veneer and adjust their moisture content to 10%;

[0033] 2. Apply the freshly prepared wood activator evenly on the surface of the veneer (double-sided coating of the core board) with a coating amount of 160g / m 2 , and the veneer assembly is carried out in a criss-cross manner according to the direction of the wood fiber texture.

[0034] 3. Turn on the hot press and set the hot press temperature to 150°C and the hot press pressure to 1.0 MPa. After the hot press temperature stabilizes, place the assembled blank into the hot press and fully press for 20 minutes before releasing the pressure.

[0035] 4. Take out the pressed plywood and place it at room temperature for 24 hours to balance until the stress inside the board is completely eliminated, thus obtaining the formaldehyde-free and environmentally friendly three-layer plywood.

[0036] 5. The dry and wet bond strengths of plywood were measured in accordance with national standards GB / T 9846-2015, “Ordinary Plywood,” and GB / T 17657-2022, “Test Methods for Physical and Chemical Properties of Wood-Based Panels and Veneered Wood-Based Panels.” The test results are shown in Table 1.

[0037] Example 3

[0038] A method for preparing nine-layer formaldehyde-free environmentally friendly plywood:

[0039] 1. Take nine sheets of 1.8mm thick poplar veneer and adjust their moisture content to 10%;

[0040] 2. Apply the freshly prepared wood activator evenly on the surface of the veneer (single-sided coating on the top board and double-sided coating on the other boards) with a coating amount of 200g / m 2 , and the veneer assembly is carried out in a criss-cross manner according to the direction of the wood fiber texture.

[0041] 3. Turn on the hot press and set the temperature to 170°C and the pressure to 1.6 MPa. After the temperature stabilizes, place the product in the hot press and fully press for 20 minutes before releasing the pressure.

[0042] 4. Take out the pressed plywood and place it at room temperature for 24 hours to balance until the stress inside the board is completely eliminated, thus obtaining the formaldehyde-free and environmentally friendly nine-layer plywood.

[0043] 5. The dry and wet bond strengths of plywood were measured in accordance with national standards GB / T 9846-2015, “Ordinary Plywood,” and GB / T 17657-2022, “Test Methods for Physical and Chemical Properties of Wood-Based Panels and Veneered Wood-Based Panels.” The test results are shown in Table 1.

[0044] Example 4

[0045] A method for preparing formaldehyde-free environmentally friendly particleboard:

[0046] 1. Take 3000g of wood shavings and adjust their moisture content to 3%;

[0047] 2. Apply the freshly prepared wood activator evenly to the wood shavings, applying an amount of 300g, and stir evenly, and spread it in sequence according to the mass ratio of 1:3:1.

[0048] 3. Turn on the hot press and set the temperature to 170°C and the pressure to 1.2 MPa. After the temperature stabilizes, place the product in the hot press and fully press for 30 minutes before releasing the pressure.

[0049] 4. Take out the pressed particleboard and place it at room temperature for 24 hours to balance until the stress inside the board is completely eliminated, thus obtaining formaldehyde-free and environmentally friendly particleboard.

[0050] 5. The internal bond, static bending strength, and elastic modulus of particleboard were measured in accordance with the national standard GB / T 4897-2015 “Particleboard”. The test results are shown in Table 2.

[0051] Comparative Example 1

[0052] 1. Take three sheets of 1.8mm thick poplar veneer and adjust their moisture content to 10%;

[0053] 2. Apply urea-formaldehyde adhesive evenly on the surface of the veneer (double-sided coating of the core board), with an application amount of 160g / m 2 , and the veneer assembly is carried out in a criss-cross manner according to the direction of the wood fiber texture.

[0054] 3. Turn on the hot press and set the hot press temperature to 150°C and the hot press pressure to 1.0 MPa. After the hot press temperature stabilizes, place the assembled blank into the hot press and fully press for 5 minutes before releasing the pressure.

[0055] 4. Take out the pressed plywood and place it at room temperature for 24 hours to balance until the stress inside the board is completely eliminated, thus obtaining a three-layer plywood.

[0056] 5. The dry and wet bond strengths of plywood were measured in accordance with national standards GB / T 9846-2015, “Ordinary Plywood,” and GB / T 17657-2022, “Test Methods for Physical and Chemical Properties of Wood-Based Panels and Veneered Wood-Based Panels.” The test results are shown in Table 1.

[0057] Comparative Example 2

[0058] 1. Take nine sheets of 1.8mm thick poplar veneer and adjust their moisture content to 10%;

[0059] 2. Apply urea-formaldehyde resin adhesive evenly on the surface of the veneer (single-sided coating on the surface plate and double-sided coating on the other plates), with a coating amount of 200g / m 2 , and the veneer assembly is carried out in a criss-cross manner according to the direction of the wood fiber texture.

[0060] 3. Turn on the hot press and set the hot press temperature to 170°C and the hot press pressure to 1.2MPa. After the hot press temperature stabilizes, place the assembled blank into the hot press and fully press for 10 minutes before releasing the pressure.

[0061] 4. Take out the pressed plywood and place it at room temperature for 24 hours to balance until the stress inside the board is completely eliminated, thus obtaining a nine-layer plywood.

[0062] 5. The dry and wet bond strengths of plywood were measured in accordance with national standards GB / T 9846-2015, “Ordinary Plywood,” and GB / T 17657-2022, “Test Methods for Physical and Chemical Properties of Wood-Based Panels and Veneered Wood-Based Panels.” The test results are shown in Table 1.

[0063] Comparative Example 3

[0064] 1. Take 3000g of wood shavings and adjust their moisture content to 3%;

[0065] 2. Apply 200g of isocyanate adhesive evenly to the wood shavings, stir evenly, and lay them in sequence according to the mass ratio of 1:3:1.

[0066] 3. Turn on the hot press and set the temperature to 170°C and the pressure to 1.2 MPa. After the temperature stabilizes, place the product in the hot press and fully press for 30 minutes before releasing the pressure.

[0067] 4. Take out the pressed plywood and place it at room temperature for 24 hours to balance until the stress inside the board is completely eliminated, thus obtaining formaldehyde-free and environmentally friendly particleboard.

[0068] 5. The internal bond, static bending strength, and elastic modulus of particleboard were measured in accordance with the national standard GB / T 4897-2015 “Particleboard”. The test results are shown in Table 2.

[0069] Table 1 Plywood performance test results

[0070]

[0071] Table 2 Particleboard performance test results

[0072]

[0073] Comparing Examples 2 and 3 with Comparative Examples 1 and 2, the plywood produced by the present invention exhibits virtually no formaldehyde emissions (reaching ENF level, ≤0.25 mg / L), and both dry and wet bond strengths meet the requirements for Class II boards in the national standard GB / T 9846-2015, "Ordinary Plywood." Comparing Example 4 with Comparative Example 3, the mechanical strength of the particleboard produced by the present invention meets the requirements for furniture-grade particleboard in a dry state in GB / T 4897-2015, "Particleboard." Therefore, the technology of this patent is more environmentally friendly than previous preparation methods and has promising practical applications.

[0074] The above description is only a specific implementation method of the present application, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with this technical field within the technical scope disclosed by the present invention and within the spirit and principles of the present invention should be covered by the scope of protection of the present invention.

Claims

1. A wood activator, comprising a polyol solution, a viscosity regulator, and a portion of an auxiliary agent.

2. The wood activator according to claim 1, characterized in that The polyol mixed solution includes any one or more of polyvinyl alcohol, polyethylene glycol and glycerol.

3. The wood activator according to claim 1, characterized in that The viscosity regulator includes any one or more of soybean powder, peanut protein powder, walnut protein powder, flour and konjac fly starch.

4. The wood activator according to claim 1, characterized in that The auxiliary agent includes any one or more of vanillin, borax, and sodium formate.

5. A method for preparing an activator, characterized in that: Based on the total weight, take 60-80% of the polyol mixed solution and 10-30% of the viscosity regulator, stir evenly for 3-5 minutes, then add 10% of the auxiliary agent and stir thoroughly for 5-8 minutes until there are no obvious particles in the system. This will give a stable wood activator.

6. A method for preparing formaldehyde-free plywood, characterized in that: Activate wood using any one of the wood activators in claims 1-4; evenly apply the prepared wood activator on the surface of a veneer, and assemble the veneers in a crisscross pattern; place the assembled veneers in a hot press, fully hot-press, and then release the pressure.

7. The plywood hot pressing process according to claim 6, characterized in that: The coating amount of wood activator is 100-200g / m 2 The core board is coated on both sides; the number of wood veneer layers is 3-13 layers in a crisscross pattern; the hot pressing temperature is 120-200℃, the hot pressing pressure is 0.8-1.6MPa, and the hot pressing time is 15-60min.

8. A method for preparing formaldehyde-free particleboard and fiberboard, characterized in that: Activate wood chips and fiber wood using any one of the wood activators in claims 1-4; evenly apply the prepared wood activator on the wood, stir it evenly and spread it in sequence; put it into a hot press, fully heat-press it and then release the pressure.

9. The hot pressing process for particleboard and fiberboard according to claim 8, characterized in that The amount of the wood activator applied is 5-12% of the total mass of the wood; the hot pressing temperature is 160-250° C., the hot pressing pressure is 0.5-6 MPa, and the hot pressing time is 10-40 minutes.

10. Formaldehyde-free plywood, particleboard and fiberboard activated by the method according to any one of claims 1 to 9.

Images