A wood activator, its preparation method and application

Abstract

This invention discloses a wood activator, its preparation method, and its application, belonging to the field of wood processing technology. The wood activator comprises a eutectic solvent and a viscosity modifier, wherein the eutectic solvent is composed of a hydrogen bond donor and a metal salt ligand. The activator can penetrate into the wood cell wall, acting on cellulose, hemicellulose, and lignin to improve their bonding ability during hot pressing, promoting the formation of a stable bonded structure and achieving self-gluing of the wood. This invention also provides a method for preparing the activator and its application in the preparation of wood composite materials such as glue-free plywood and glue-free particleboard. The wood composite materials prepared by this method do not contain added aldehyde adhesives, and the formaldehyde emission level reaches ENF level. Their mechanical properties and water resistance meet relevant national standards, exhibiting green environmental protection and low cost, and showing good prospects for industrial application.

Description

Technical Field

[0001] This invention belongs to the field of wood processing technology, specifically relating to a wood activator based on a eutectic solvent and its preparation method, which can be used in the preparation of glue-free plywood, glue-free particleboard, glue-free fiberboard and other wood composite materials. Background Technology

[0002] With increasingly scarce forest resources and growing awareness of ecological environmental protection, the timber processing industry faces multiple challenges, including greater difficulty in obtaining raw materials and the urgent need to improve resource utilization efficiency. Wood-based composite materials, as important products for the high-value utilization of timber resources, can fully utilize wood raw materials and improve resource utilization efficiency, finding wide applications in construction, furniture, interior decoration, and transportation. Plywood, particleboard, fiberboard, and oriented strand board are all typical examples of wood-based composite materials.

[0003] Traditional wood-based composite materials are primarily manufactured using petrochemical-derived synthetic adhesives such as urea-formaldehyde resin, phenolic resin, and melamine-formaldehyde resin. While these adhesives offer high bonding strength and good durability, they commonly suffer from formaldehyde release. Formaldehyde, a volatile organic compound, can cause indoor air pollution and even harm human health with long-term release. As national environmental policies become increasingly stringent and consumers demand green home furnishings, the shortcomings of traditional wood-based composite materials in terms of environmental performance are becoming increasingly apparent. Developing formaldehyde-free, low-carbon, and renewable bonding technologies has become a crucial direction for technological upgrading in the industry.

[0004] In recent years, utilizing the natural components of wood to achieve self-gluing has become an important research direction for glue-free wood materials. However, due to the dense cell wall structure of wood and the low reactivity of its natural components, it is difficult to form a stable bonded structure under conventional hot-pressing conditions. Therefore, it is necessary to effectively activate the natural components of wood. Current research has utilized methods such as steam explosion, ionic liquids, and eutectic solvents to pretreat wood, but existing technologies mainly focus on wood fiber separation, biomass component extraction, or wood softening. Research on activating the natural components of wood using eutectic solvents to improve the self-bonding ability of wood and its application in the preparation of glue-free plywood, particleboard, fiberboard, and other wood materials remains limited.

[0005] Therefore, developing a novel low-eutectic wood activator that can activate the natural components of wood and improve its self-bonding ability is of great significance for realizing glue-free manufacturing of wood materials, reducing the amount of adhesive used, and promoting the development of green wood processing technology. Summary of the Invention

[0006] The main objective of this invention is to provide a wood activator based on a eutectic solvent and its preparation method. This activator can penetrate the cell walls of wood, acting on the natural components of wood to enhance the binding capacity of cellulose, hemicellulose, and lignin during hot pressing, promoting the formation of a stable bonded structure among the natural wood components. This avoids the use of external adhesives, achieving self-bonding within the wood itself. This invention further provides the application of the aforementioned wood activator in the preparation of glue-free plywood, glue-free particleboard, fiberboard, and other wood-based composite materials. The resulting wood-based composite materials are green, environmentally friendly, and economical, and their physical and mechanical properties, as well as water resistance, meet the requirements of relevant national standards, enabling their wide application in furniture, building materials, and decorative materials. This method provides a new approach for the sustainable production of formaldehyde-free, environmentally friendly wood-based composite materials.

[0007] This invention provides a wood activator based on a eutectic solvent, comprising a eutectic solvent and a viscosity modifier.

[0008] The eutectic solvent is composed of hydrogen bond donors and metal salt ligands.

[0009] The viscosity modifier is used to adjust the viscosity of the wood activator to improve its application performance, penetration performance, and uniform distribution on the wood surface. Those skilled in the art can select a suitable viscosity modifier according to actual needs.

[0010] Preferably, the hydrogen bond donor includes at least one of acetamide, glycerol, and caffeic acid.

[0011] Preferably, the metal salt includes at least one of copper acetate and magnesium lactate.

[0012] Preferably, the molar ratio of the hydrogen bond donor to the metal salt is (1~10):1.

[0013] Preferably, the viscosity modifier is konjac starch and water.

[0014] Preferably, the wood activator comprises 70-85% eutectic solvent and 15-30% viscosity modifier by mass percentage.

[0015] The present invention also provides a method for preparing the wood activator, comprising the following steps:

[0016] (1) The hydrogen bond donor and the metal salt ligand are mixed in a set molar ratio and heated and stirred at 80 °C to form a homogeneous and transparent eutectic solvent;

[0017] (2) Add viscosity regulator to the obtained eutectic solvent and stir thoroughly for 5-10 min until the system is uniform and there are no obvious particles, thus obtaining wood activator.

[0018] The present invention also provides a wood activation method, wherein the above-mentioned wood activator is applied to the surface of the wood or treated by impregnation, so that the wood activator penetrates into the cell wall of the wood and activates the natural components of the wood; then hot pressing is performed to promote the formation of a stable bond structure of the natural components of the wood.

[0019] The wood activator described in this invention can be used in the preparation of glue-free plywood, glue-free particleboard, glue-free fiberboard, oriented strand board and other wood composite materials.

[0020] Formaldehyde-free wood composite materials prepared by any formulation and preparation process parameters of the present invention are also within the scope of protection of the present invention. Detailed Implementation

[0021] 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 and illustrate the technical solutions described in the present invention, but should not be construed as limiting the present invention.

[0022] Example 1

[0023] A method for preparing a wood activator:

[0024] According to the mass fraction, first take 43.4 g of copper acetate and 40 g of glycerol solution and mix them evenly as the base solvent, then add 10.85 g of konjac powder and 10 g of water, and stir evenly at 80 ℃ for 5 min to ensure that the plant extract is fully dispersed and dissolved in the system.

[0025] Example 2

[0026] A method for activating wood veneer:

[0027] Poplar veneer was impregnated in the aforementioned eutectic solvent and treated at 80 °C for 4 h. During the treatment, the eutectic solvent penetrated the wood cell wall structure and interacted with cellulose, hemicellulose, and lignin through hydrogen bonding, reducing cell wall rigidity and improving the surface activity and wettability of the veneer.

[0028] Example 3

[0029] A method for activating wood shavings:

[0030] The dried wood shavings were added to a eutectic solvent at a dry weight ratio of 1:5 to 1:10, and impregnated at 80 °C for 4 h. During the activation process, the eutectic solvent fully penetrated the cell wall structure of the wood shavings, interacting with cellulose, hemicellulose, and lignin through hydrogen bonding, promoting cell wall relaxation, reducing the rigidity of the wood material, and improving the surface activity and interfacial bonding ability of the wood shavings.

[0031] Example 4

[0032] A method for preparing a three-layer formaldehyde-free environmentally friendly plywood:

[0033] 1. Take three pieces of activated poplar veneer, each 1.8 mm thick;

[0034] 2. Apply the freshly prepared wood activator evenly to the surface of the veneer (double-sided coating for the core board), with a coating amount of 160 g / m². 2 The veneer blanks are assembled in a crisscross pattern according to the direction of the wood fiber grain.

[0035] 3. Turn on the hot press, set the hot pressing temperature to 150℃ and the hot pressing pressure to 1.0 MPa. After the hot press temperature stabilizes, place the assembled slab into the hot press and press it fully for 20 minutes, then release the pressure.

[0036] 4. Remove the pressed plywood and place it at room temperature for 24 hours to allow the internal stress of the board to be completely eliminated, thus obtaining formaldehyde-free environmentally friendly three-layer plywood.

[0037] 5. The dry and wet bonding strength of the plywood was determined in accordance with the 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 Decorative Wood-based Panels". The test results are shown in Table 1.

[0038] Example 5

[0039] A method for preparing a nine-layer formaldehyde-free environmentally friendly plywood:

[0040] 1. Take nine sheets of activated poplar veneer, each 1.8 mm thick;

[0041] 2. Apply the freshly prepared wood activator evenly to the surface of the veneer (single-sided coating for the top veneer, double-sided coating for the remaining boards), with a coating amount of 200 g / m². 2 The veneer blanks are assembled in a crisscross pattern according to the direction of the wood fiber grain.

[0042] 3. Turn on the hot press, set the hot pressing temperature to 170℃ and the hot pressing pressure to 1.6 MPa. After the hot press temperature stabilizes, place the object in the hot press and press for 20 minutes, then release the pressure.

[0043] 4. Remove the pressed plywood and place it at room temperature for 24 hours to allow the internal stress of the board to be completely eliminated, thus obtaining a formaldehyde-free, environmentally friendly nine-layer plywood.

[0044] 5. The dry and wet bonding strength of the plywood was determined in accordance with the 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 Decorative Wood-based Panels". The test results are shown in Table 1.

[0045] Example 6

[0046] A method for preparing formaldehyde-free environmentally friendly particleboard:

[0047] 1. Take 3000 g of activated wood shavings;

[0048] 2. Apply the freshly prepared wood activator evenly to the wood shavings at a rate of 300 g, and stir evenly. Then, spread the shavings in a mass ratio of 1:3:1.

[0049] 3. Turn on the hot press, set the hot pressing temperature to 170℃ and the hot pressing pressure to 1.2 MPa. After the hot press temperature stabilizes, place the object in the hot press and press for 30 minutes, then release the pressure.

[0050] 4. Remove the pressed particleboard and place it at room temperature for 24 hours to allow the internal stress of the board to be completely eliminated, thus obtaining formaldehyde-free environmentally friendly particleboard.

[0051] 5. The internal bond strength, static bending strength and modulus of elasticity of particleboard were determined according to the national standard GB / T 4897-2015 "Particleboard". The test results are shown in Table 2.

[0052] Comparative Example 1

[0053] 1. Take three ordinary poplar veneers with a thickness of 1.8 mm;

[0054] 2. Apply urea-formaldehyde resin adhesive evenly to the surface of the veneer (double-sided coating for the core board), with an application rate of 160 g / m². 2 The veneer blanks are assembled in a crisscross pattern according to the direction of the wood fiber grain.

[0055] 3. Turn on the hot press, set the hot pressing temperature to 150℃ and the hot pressing pressure to 1.0 MPa. After the hot press temperature stabilizes, place the assembled slab into the hot press and press it fully for 5 minutes, then release the pressure.

[0056] 4. Remove the pressed plywood and place it at room temperature for 24 hours to allow the internal stress of the board to be completely eliminated, thus obtaining a three-layer plywood.

[0057] 5. The dry and wet bonding strength of the plywood was determined in accordance with the 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 Decorative Wood-based Panels". The test results are shown in Table 1.

[0058] Comparative Example 2

[0059] 1. Take nine ordinary poplar veneers, each 1.8 mm thick;

[0060] 2. Apply urea-formaldehyde resin adhesive evenly to the surface of the veneer (single-sided coating for the top veneer, double-sided coating for the remaining veneers), with a coating amount of 200 g / m². 2 The veneer blanks are assembled in a crisscross pattern according to the direction of the wood fiber grain.

[0061] 3. Turn on the hot press, set the hot pressing temperature to 170℃ and the hot pressing pressure to 1.2 MPa. After the hot press temperature stabilizes, place the assembled slab into the hot press and press it fully for 10 minutes, then release the pressure.

[0062] 4. Remove the pressed plywood and place it at room temperature for 24 hours to allow the internal stress of the board to be completely eliminated, thus obtaining a nine-layer plywood.

[0063] 5. The dry and wet bonding strength of the plywood was determined in accordance with the 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 Decorative Wood-based Panels". The test results are shown in Table 1.

[0064] Comparative Example 3

[0065] 1. Take 3000 g of ordinary wood shavings;

[0066] 2. Apply the isocyanate adhesive evenly to the wood shavings, using 200 g of the adhesive, and stir evenly. Then, lay the shavings in a mass ratio of 1:3:1.

[0067] 3. Turn on the hot press, set the hot pressing temperature to 170℃ and the hot pressing pressure to 1.2 MPa. After the hot press temperature stabilizes, place the object in the hot press and press for 30 minutes, then release the pressure.

[0068] 4. Remove the pressed plywood and place it at room temperature for 24 hours to allow the internal stress of the board to be completely eliminated, thus obtaining formaldehyde-free environmentally friendly particleboard.

[0069] 5. The internal bond strength, static bending strength and modulus of elasticity of particleboard were determined according to the national standard GB / T 4897-2015 "Particleboard". The test results are shown in Table 2.

[0070] Table 1. Performance Test Results of Plywood

[0071] Example 4 1.75 0.75 0.037 (ENF) Example 5 1.35 0.88 0.041 (ENF) Comparative Example 1 1.61 0.72 0.56 Comparative Example 2 1.24 0.76 0.61

[0072] Table 2 Performance Test Results of Particleboard

[0073] Example 6 0.48 13.5 2000 Comparative Example 3 0.45 12.9 1958

[0074] Compared with Examples 4 and 5 and Comparative Examples 1 and 2, the plywood prepared by this invention has virtually no formaldehyde release (reaching ENF level, ≤0.25 mg / L), and both its dry and wet bonding strengths meet the requirements for Class II boards in the national standard GB / T 9846-2015 "Ordinary Plywood". Compared with Example 6 and Comparative Example 3, the particleboard prepared by this invention meets the mechanical strength requirements for furniture-type particleboard in the dry state in GB / T 4897-2015 "Particleboard". Therefore, the technology of this patent is more environmentally friendly than previous preparation methods and has certain practical application prospects.

[0075] The above description is merely a specific embodiment of this application, but the scope of protection of this invention is not limited thereto. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the scope of the technology disclosed in this invention, and within the spirit and principles of this invention, should be covered within the scope of protection of this invention.

Claims

1. A wood activator based on a eutectic solvent, characterized in that, It includes a eutectic solvent and a viscosity modifier; the eutectic solvent is composed of hydrogen bond donors and metal salt ligands, and the wood activator can penetrate into the wood cell wall, act on the natural components of the wood, and improve the binding ability of the natural components of the wood during the hot pressing process.

2. The wood activator according to claim 1, characterized in that, The natural components of the wood include cellulose, hemicellulose, and lignin.

3. The wood activator according to claim 1, characterized in that, The hydrogen bond donor includes at least one of acetamide, glycerol, and caffeic acid.

4. The wood activator according to claim 1, characterized in that, The metal salt coordination component includes at least one of copper acetate and magnesium lactate.

5. The wood activator according to claim 1, characterized in that, The molar ratio of hydrogen bond donor to metal salt coordination component in the eutectic solvent is (1~10):

1.

6. A method for preparing a wood activator, characterized in that, Add 70-85% eutectic solvent and 15-30% viscosity modifier by total mass, stir thoroughly at 80℃ for 5-10 min until there are no obvious particles in the system, and a stable wood activator is obtained.

7. A method for activating wood, characterized in that, The wood activator described in any one of claims 1-6 is applied to the surface of wood to impregnate the wood, allowing the activator to penetrate into the wood cell walls and activate the natural components of the wood.

8. The method according to claim 7, characterized in that, The bonding of the wood relies primarily on the bonding structure formed by the natural components of the wood, rather than on the adhesive layer formed by added glue.

9. The application of the wood activator according to any one of claims 1-6 or the wood activation method according to any one of claims 7-8 in the preparation of glue-free plywood, particleboard, fiberboard, oriented strand board and other wood composite materials.