A method for preparing wood fiber products and the wood fiber products thereof.

Abstract

The purpose of this invention is to provide a method for preparing wood fiber products and the wood fiber products themselves, comprising the following steps: obtaining wood boards of a predetermined thickness; drying the wood boards and then impregnating them in a predetermined ionic liquid solution under vacuum pressure to obtain impregnated boards; removing the filtrate from the impregnated boards and then processing them under a predetermined temperature and pressure to obtain hot-pressed boards; and immersing the hot-pressed boards in a cleaning solution for displacement treatment to obtain all-wood fiber boards. Compared with the prior art, the method for preparing wood fiber products and the wood fiber products provided by this invention can improve their mechanical properties while also improving their environmental performance.

Description

Technical Field

[0001] This invention relates to the field of wood product processing technology, and more particularly to a method for preparing wood fiber products and wood fiber products. Background Technology

[0002] Fast-growing timber species refer to tree varieties that grow quickly, mature early, and have short rotation periods. Common examples in my country include *Sophora japonica*, poplar, eucalyptus, and willow. Some imported fast-growing industrial timbers commonly used include *Sophora japonica*, Radiata pine, Taeda (same as Lobllolly-pine), Southern Yellow pine, Douglas fir, and Araucaria (Hoop pine). Timber made from these fast-growing species is called fast-growing timber. It is usually softer and is generally used for papermaking, construction, and as core material for boards. Some is also used in furniture making, but all require some processing, such as degreasing and drying, to transform it into high-quality boards.

[0003] Fast-growing timber, due to its rapid growth, suffers from a major problem: its porous texture, high porosity, and low density result in low mechanical strength and properties. For example, Chinese fir, a major timber species native to southern regions, is an evergreen tree with a wide distribution and rapid growth. While Chinese fir has good processing properties, is resistant to decay and insects, and has beautiful grain and color, its fast-growing form is of poor quality. Its structure is loose and extremely uneven, with low strength and hardness, poor wear resistance, and easy moisture absorption. Therefore, fast-growing timber has traditionally been primarily used for engineered wood products, papermaking, packaging materials, and construction formwork, rather than furniture, especially high-end furniture. Furniture wood needs to possess high strength, resistance to warping, and thermal insulation properties. With environmental degradation and the scarcity of timber resources, fast-growing timber has become an indispensable renewable and environmentally friendly resource. However, fast-growing timber suffers from disadvantages such as low density, low hardness, low strength, and susceptibility to warping.

[0004] Wood is a viscoelastic material, but the veneers formed by rotary cutting or slicing wood are relatively thin, making them prone to cracking when directly hot-pressed, and resulting in poor stability after molding. Therefore, veneer modification is necessary to ensure the quality of the molded products. In existing technologies, there are generally two methods for processing fast-growing wood into fiber products. One method involves shaving the wood, crushing it into fibers, adding appropriate adhesives and modifiers, and then pressing and compounding it, as disclosed in patent application CN201811207798.1. The other method, as disclosed in patent application CN107584613A, involves drying the fast-growing wood and then immersing it in a corresponding modifying liquid for vacuum pressure treatment to improve its density, mechanical strength, and other properties.

[0005] However, during use, the wood prepared by the first method has poor mechanical properties and uses a large amount of adhesive, making it prone to producing large amounts of formaldehyde and cracking, resulting in poor stability. Furthermore, the wood prepared by the second method contains fixatives, such as any one or more combinations of dimethyloldiethylvinyl urea, modified etherified hexamethylol melamine resin, or hydroxymethylphenol pre-shrinkage liquid, which still easily cause formaldehyde to volatilize after molding, resulting in poor environmental performance. In addition, cracking is very likely to occur during the molding process, leading to poor stability.

[0006] Therefore, how to prepare a wood fiber product that improves its mechanical properties and stability while reducing environmental pollution is a technical problem that this invention urgently needs to solve. Summary of the Invention

[0007] The technical problem to be solved by the present invention is how to provide a method for preparing wood fiber products and wood fiber products that improve their mechanical properties while reducing environmental pollution.

[0008] To solve the above-mentioned technical problems, the present invention provides a method for preparing wood fiber products, comprising the following steps:

[0009] Obtain wood-based panels of a preset thickness;

[0010] After the wood-based board is dried, it is impregnated in a pre-set ionic liquid solution and subjected to vacuum pressure treatment to obtain impregnated board. The ionic liquid solution includes at least: molten salt solvent and co-solvent.

[0011] After removing the filtrate from the impregnated plate, it is placed in an environment with a preset temperature and a preset pressure to obtain a hot-pressed plate.

[0012] The hot-pressed board is placed in a cleaning solution for displacement treatment to obtain an all-wood fiberboard.

[0013] Further, as a preferred embodiment, the step of obtaining a wood board of a predetermined thickness includes:

[0014] The wood-based panels are formed by rotary cutting or planing fast-growing timber, wherein the preset thickness is 1.9~2.1mm.

[0015] Further, as a preferred embodiment, the ratio of the molten salt solvent to the co-solvent is 10:90 to 40:60.

[0016] Further, as a preferred embodiment, the ratio of the molten salt solvent to the co-solvent is 20:80 to 40:60.

[0017] Further, preferably, the molten salt solvent includes any one or a combination of 1-butyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium chloride, 1-allyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium acetate, 1-butyl-3-methylimidazolium acetate or 1-allyl-3-methylimidazolium acetate.

[0018] Further, preferably, the co-solvent is any one or a combination of two or more of ethylene glycol, polyethylene glycol, dimethyl sulfoxide, and N,N-dimethylformamide.

[0019] Further, preferably, the melting point of the molten salt solvent is below 100 °C.

[0020] Further, preferably, the step of drying the wood-based board and then impregnating it in a pre-set ionic liquid solution under vacuum pressure to obtain the impregnated board includes:

[0021] After the wood-based board is dried, it is immersed in an ionic liquid solution at a preset immersion temperature of 80~120℃.

[0022] The impregnated wood board is obtained by placing the ionic liquid solution impregnated with the wood board under a vacuum environment for at least 30 to 60 minutes.

[0023] Further, preferably, the step of removing the filtrate from the impregnated board and then processing it under a preset temperature and pressure to obtain a hot-pressed board includes:

[0024] After removing the filtrate from the impregnated board, it is wrapped with a pre-set film to form a board to be molded and then placed in a hot press.

[0025] The sheet material to be molded is subjected to hot pressing in the hot press at a set temperature of 150~180℃ and a set pressure of 0.5~5MPa for at least 10~30 minutes to obtain the hot-pressed sheet material.

[0026] Further, as a preferred embodiment, the step of immersing the hot-pressed board in a cleaning solution for displacement treatment to obtain an all-wood fiberboard includes:

[0027] Prepare the cleaning solution using deionized water or ethanol, and keep the temperature of the cleaning solution within the range of 20°C to 26°C.

[0028] The hot-pressed board is immersed in the cleaning solution for extraction for at least 30 to 720 minutes to obtain the all-wood fiberboard.

[0029] Furthermore, preferably, the cleaning solution is not limited to deionized water, but can also be other solutions that can achieve the replacement treatment of molten salt solvent and co-solvent, such as ethanol.

[0030] Further, as a preferred embodiment, after the step of immersing the hot-pressed board in a cleaning solution for displacement treatment to obtain an all-wood fiberboard, the method further includes:

[0031] One or more of the aforementioned all-wood fiberboards are placed into a molding mold and then placed in a hot press for densification and shaping treatment to obtain a molded board. The densification and shaping treatment is performed at a pressure of at least 0.5~10MPa, a temperature of 150~180℃, and a time of 10min~30min.

[0032] The molded board is cooled to obtain an all-wood fiber molded board.

[0033] Further, as a preferred embodiment, the coating is a polytetrafluoroethylene (PTFE) film.

[0034] This application also provides a wood fiber product, which is prepared by the above-described method for preparing wood fiber products.

[0035] Furthermore, as a preferred embodiment, the aforementioned wood-based panels may preferably be any one or a combination of poplar, locust, radiata pine, fire pine, longleaf pine, Douglas fir, and South American pine wood.

[0036] Compared with existing technologies, the method for preparing wood fiber products provided by this invention can improve their mechanical properties and stability while reducing environmental pollution. Attached Figure Description

[0037] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0038] Figure 1 Schematic flowchart of the method for preparing wood fiber products in the first embodiment of the present invention Figure 1 ;

[0039] Figure 2 Schematic flowchart of the method for preparing wood fiber products in the first embodiment of the present invention Figure 2 ;

[0040] Figure 3 : A schematic diagram of the microstructure of the all-wood fiberboard provided in Embodiment 1 of the present invention;

[0041] Figure 4 : A schematic diagram of the microstructure of the all-wood fiberboard provided in Embodiment 2 of the present invention;

[0042] Figure 5 : A schematic diagram of the microstructure of the all-wood fiberboard provided in Embodiment 3 of the present invention;

[0043] Figure 6 : A schematic diagram of the microstructure of the wood-based panel provided in Comparative Example 1 of the present invention;

[0044] Figure 7 : A schematic diagram of the assembly of the molding die in the first embodiment of the present invention;

[0045] Figure 8 : A schematic diagram of the cooperation between the upper and lower pressing members in the first embodiment of the present invention;

[0046] Figure 9 : A schematic diagram of the upper pressing component in the first embodiment of the present invention;

[0047] Figure 10 A schematic diagram of the specific process of step S20 in the first embodiment of the present invention;

[0048] Figure 11 A schematic diagram of the specific process of step S30 in the first embodiment of the present invention;

[0049] Figure 12 A schematic flowchart of a preferred method for preparing a wood fiber product in the first embodiment of the present invention;

[0050] Figure label:

[0051] Upper pressing part 1, lower pressing part 2, molded part 3, boss 11, concave area 21, accommodating area 31. Implementation

[0052] The following specific embodiments illustrate the concept of the present invention by using the preparation method of wood fiber products as an example.

[0053] Implementation

[0054] like Figure 1 and Figure 2 As shown, the first embodiment of the present invention provides a method for preparing a wood fiber product, comprising the following steps:

[0055] Step S10: Obtain a wood board of preset thickness.

[0056] Step S20: After drying the wood board, it is impregnated in a preset ionic liquid solution and subjected to vacuum pressure treatment to obtain impregnated board. The ionic liquid solution includes at least: molten salt solvent and co-solvent.

[0057] Step S30: After removing the filtrate from the impregnated plate, it is placed in an environment with a preset temperature and preset pressure to obtain a hot-pressed plate.

[0058] Step S40: Immerse the hot-pressed board in a cleaning solution for displacement treatment to obtain a full wood fiberboard. It should be noted that in this embodiment, "full wood fiberboard" refers to wood fiber products with a high wood content, for example, a wood content of over 95%.

[0059] As can be seen from the above steps, since molten salt solvent and co-solvent are used as ionic liquid solutions to impregnate and hot-press the wood-based panels in this embodiment, some of the wood-based panels, especially the non-wood components, can be dissolved. Then, through the extraction process using a cleaning solution, such as deionized water, the components of the ionic liquid are replaced, and the dissolved parts, especially the wood parts, can be reorganized in the veneer structure. Therefore, it can not only enhance the plasticity of the prepared all-wood fiberboard, but also improve the anisotropy of the all-wood fiberboard, utilize its plasticity to achieve densification, and improve the mechanical properties of the wood-based panels. Moreover, cracks are not easily generated during the hot-pressing process, so as to facilitate the subsequent preparation of all-wood cellulose composite products with better mechanical properties.

[0060] Furthermore, through the above steps, the molten salt solvent and co-solvent in the ionic liquid that partially dissolves and binds to the wood-based panels, such as 1-butyl-3-methylimidazolium chloride (molten salt solvent) and polyethylene glycol (co-solvent), can be replaced by the cleaning solution (e.g., deionized water). Therefore, the performance modification treatment of the wood-based panels is achieved without introducing new components, retaining the environmental friendliness of the wood-based panels, while also having a certain strength and the characteristics of not deforming, not twisting and having good stability.

[0061] In addition, the density, shape and structure of the fiber products prepared through the above steps are designable. They can be designed into sheets, bent products, or packaging containers with certain shapes and structures to meet different needs. This is something that cannot be achieved with traditional wood, and it has great promotion and application value.

[0062] Further, as a preferred embodiment, the step of obtaining the wood-based board of the preset thickness, i.e., step S10 above, specifically involves: rotary cutting or planing fast-growing timber to form the wood-based board, wherein the preset thickness is 1.9~2.1mm. It should be noted that the fast-growing timber can preferably be any one of poplar, *Sophora japonica*, Radiata pine, Taeda (also known as Lobllolly-Pine), Southern Yellow Pines, Douglas Fir, and *Araucaria* (Hoop pine). By selecting widely used low-quality fast-growing timber, the utilization rate of timber can be improved, its use value increased, and economic benefits enhanced.

[0063] Further, as a preferred embodiment, the ratio of the molten salt solvent to the co-solvent is 10:90 to 40:60. This ratio, for example using polyethylene glycol, helps to reduce the viscosity of the ionic liquid solution, thereby increasing the rate and efficiency of lignin dissolution. Furthermore, it also gives the ionic liquid solution good plasticizing properties.

[0064] Further, preferably, the molten salt solvent is 1-butyl-3-methylimidazolium chloride.

[0065] Because 1-butyl-3-methylimidazolium chloride is a low-temperature molten salt with a melting point below 100 °C, and its structure is entirely composed of anions and cations, it exists as a liquid at or near room temperature. Compared to traditional organic solvents, water, and supercritical fluids, the ionic liquid formed by 1-butyl-3-methylimidazolium chloride has almost no vapor pressure, is non-volatile, colorless, and odorless, thus effectively eliminating environmental pollution problems. Furthermore, the ionic liquid formed by 1-butyl-3-methylimidazolium chloride exhibits excellent solubility for a wide range of inorganic and organic substances, possessing both solvent and catalytic functions. Its solubility for inorganic substances, water, organic substances, and polymers can be adjusted through the design of anions and cations, making it not only simple to process but also recyclable, thereby improving its economic efficiency.

[0066] Further, as a preferred option, such as Figure 10 As shown, the step of drying the wood-based board and then impregnating it in a preset ionic liquid solution under vacuum pressure to obtain the impregnated board, i.e., step S20, includes the following steps:

[0067] Step S201: After drying the wood-based panel, it is immersed in an ionic liquid solution at a preset immersion temperature of 80~120℃. It should be noted that, in this embodiment, the wood-based panel is preferably completely submerged in the ionic liquid solution.

[0068] Step S202: The ionic liquid solution impregnating the wood-based board is placed in a vacuum environment for at least 30-60 minutes to obtain the impregnated board. It should be noted that, in this embodiment, it is preferable to place the container holding the ionic liquid solution impregnating the wood-based board in a vacuum device and perform vacuum treatment under a vacuum degree greater than or equal to 0.1 MPa to obtain the aforementioned vacuum environment.

[0069] The above steps allow the ionic liquid solution to better penetrate the pores of the wood-based panels while they are impregnated. Vacuuming effectively removes air from these pores, and negative pressure further promotes the penetration of the ionic liquid solution, achieving thorough modification. Furthermore, since the molten salt in this embodiment is solid at room temperature, heating melts it. Setting the treatment time under vacuum to 30-60 minutes prevents both insufficient heating (which would prevent the ionic liquid solution from penetrating the wood-based panels) and excessive heating (which would dissolve too much wood content into the solution and weaken the mechanical properties of the all-wood fiber products).

[0070] Further, as a preferred embodiment, the step of removing the filtrate from the impregnated board and then processing it under a preset temperature and pressure to obtain a hot-pressed board is as follows: Figure 11 As shown, step S30 includes:

[0071] Step S301: After removing the filtrate from the impregnated board, wrap it with a pre-set film to form a board to be molded, and then place it in a hot press. In this embodiment, the film is preferably a polytetrafluoroethylene (PTFE) film.

[0072] Step S302: The material to be molded is hot-pressed in the hot press at a set temperature of 150~180℃ and a set pressure of 0.5-5MPa for at least 10~30 minutes to obtain the hot-pressed material.

[0073] By following the above steps, cracks and other phenomena can be effectively prevented from occurring in the impregnated boards during the hot-pressing process, thereby improving their mechanical properties and further enhancing their environmental performance.

[0074] Further, as a preferred embodiment, the step of immersing the hot-pressed board in deionized water under constant temperature conditions for displacement treatment to obtain an all-wood fiberboard, i.e., step S40, specifically includes:

[0075] The hot-pressed board is immersed in deionized water for at least 30 to 720 minutes to obtain the all-wood fiberboard, wherein the temperature of the deionized water is 24℃ to 26℃.

[0076] As can be seen from the above steps, the hydrophilicity of ionic liquid solutions can be utilized to extract ionic liquid solutions from hot-pressed plates by means of extraction, while the dissolved components in the hot-pressed plates are solidified and regenerated to improve their mechanical properties.

[0077] Furthermore, it should be noted that the extraction time can be determined according to the different uses of the all-wood fiber products prepared from the all-wood fiberboard, so as to meet the different performance requirements of all-wood fiber products. This embodiment only uses the above example as an illustration.

[0078] Further, as a preferred option, such as Figure 12 As shown, the step of immersing the hot-pressed board in a cleaning solution for displacement treatment to obtain all-wood fiberboard, i.e., after step S40, further includes:

[0079] Step S50: Place at least one or more of the whole wood fiberboards into a molding mold and place them in a hot press for densification and shaping treatment to obtain a molded board, wherein the densification and shaping treatment is performed at least 0.5~10MPa, at a temperature of 150~180℃, and for a time of 10min~30min.

[0080] Step S60: Cool the molded board to obtain a full wood fiber molded board.

[0081] The above steps demonstrate that wood-based panels can be modified and molded simultaneously to obtain all-wood fiber molded boards, thus improving production efficiency, shortening the production cycle, and increasing economic benefits. Furthermore, molding the boards through compression molding, and applying appropriate temperature and pressure through the molding die, enhances the board's plasticity, allowing for the design of desired shapes and preventing cracks from appearing during the fabrication of the finished fiber products. This prevents issues with the quality of the all-wood fiber molded boards and avoids poor shaping due to excessively low temperatures or pressures during the molding process. For example, excessively high temperatures during molding can affect the composition of the modified wood-based panels, while excessive pressure can cause cracks in the molded products, thus impacting their quality.

[0082] In detail, such as Figures 7 to 9 As shown, the molding die in this embodiment includes an upper pressing member 1, a lower pressing member 2 that cooperates with the upper pressing member 1, and a molding member 3 that is disposed between the upper pressing member 1 and the lower pressing member 2 and is used to place the all-wood fiberboard.

[0083] The lower pressing member 2 has a recessed area 21 for placing the molded member 3, the molded member 3 has a receiving area 31 for placing the all-wood fiberboard, and the upper pressing member 1 has a boss 11 for inserting into the receiving area 31. The shapes of the recessed area 21, the receiving area 31, and the boss 11 are compatible. Furthermore, the top flange of the molded member 3 is exposed between the upper pressing member 1 and the lower pressing member 2 after the upper pressing member 1 and the lower pressing member 2 are pressed together.

[0084] Specifically, the all-wood fiberboard is placed on the flat bottom of the receiving area 31 of the molding part 3. The upper pressing part 1, the molding part 3 and the lower pressing part 2 can be stacked in sequence to achieve the densification and shaping of the all-wood fiberboard. After being placed in a hot press and processed at a preset temperature and pressure, it is cooled to obtain an all-wood fiberboard molded board.

[0085] Obviously, it should be noted that in this embodiment, the molding die may not have the molding part 3, but may only consist of the upper pressing part 1 and the lower pressing part 2 that cooperates with the upper pressing part 1. The all-wood fiberboard can be placed on the bottom of the concave area 21 so that the compaction and shaping process can be achieved by pressing the upper pressing part 1 and the lower pressing part 2 together. This embodiment is only described as an example where the molding die can be composed of the upper pressing part 1, the lower pressing part 2 that cooperates with the upper pressing part 1, and the molding part 3.

[0086] In addition, it is worth mentioning that the shape of the boss 11 in this embodiment can be a block structure such as a cube, or a trapezoidal structure, etc., which will not be described or limited in detail here.

[0087] To better illustrate the above method, the following examples are provided for brief explanation:

[0088] Vacuum equipment model and parameters: Vacuum drying oven DZF-6020AB. Vacuum degree ≤133Pa.

[0089] Hot press model and parameters: HP-100. The instrument's maximum operating temperature is 500℃, and the maximum pressure that can be applied to the sample at this temperature is 5T.

[0090] Raw material for wood-based panels: poplar;

[0091] Test sample dimensions: 30 mm × 25 mm × 1.8 mm;

[0092] The ionic liquid solution includes: 1-butyl-3-methylimidazolium chloride (molten salt solvent) and polyethylene glycol (co-solvent).

[0093] The coating material is polytetrafluoroethylene film with a thickness of 0.02mm-0.5mm.

[0094] Cleaning solution: Deionized water.

[0095] Example 1

[0096] This embodiment provides an all-wood fiberboard, which is prepared by the above-mentioned method for preparing wood fiber products. Specifically, the wood board in this embodiment has a thickness of 2mm. The wood board is a veneer with a thickness of 2mm formed by slicing fast-growing logs. After drying, the quality is kept constant, and the thickness of the veneer is ensured to be uniform with an error controlled within ±0.1mm.

[0097] The above ionic liquid solution is a compound of 1-butyl-3-methylimidazolium chloride and polyethylene glycol in a ratio of 20:80.

[0098] After the wood-based boards are dried, they are impregnated in a pre-set ionic liquid solution and subjected to vacuum pressure treatment to obtain impregnated boards. The parameters of the vacuum environment during the process are: vacuum degree of 0.1 MPa, impregnation temperature of 80℃, and treatment time under vacuum conditions of 60 min.

[0099] After removing the filtrate from the impregnated sheet, it is wrapped with a pre-set film to form the molded sheet, which is then placed in a hot press for hot pressing. The hot press is set to a temperature of 180°C and a pressure of 0.5 MPa. The hot pressing time is 10 minutes. The film is a polytetrafluoroethylene (PTFE) film.

[0100] In the step of immersing the hot-pressed board in deionized water for displacement treatment under constant temperature conditions to obtain all-wood fiberboard, the temperature of the deionized water is 25±1℃ and controlled by a water bath. The total extraction time is 720 minutes, with the deionized water being changed every 20 minutes for the first 20 minutes, and then every 60 minutes after 120 minutes.

[0101] In the step of placing a whole wood fiberboard into a molding mold and then placing it in a hot press for densification and shaping to obtain a molded board, the molding time is 20 minutes, the set pressure of the hot press is 0.5 MPa, and the set temperature of the hot press is 150°C.

[0102] Example 2

[0103] This embodiment provides a whole wood fiberboard, which is prepared by the preparation method of wood fiber products in the above embodiment 1. Specifically, the thickness of the wood board in this embodiment is 2mm. The wood board is a veneer with a thickness of 2mm formed by slicing fast-growing logs. After drying, the quality reaches a constant value, and the thickness of the veneer is ensured to be uniform with an error controlled within ±0.1mm.

[0104] The above ionic liquid solution is a compound of 1-butyl-3-methylimidazolium chloride and polyethylene glycol in a ratio of 30:70.

[0105] After drying the wood-based panels, they are impregnated in a pre-set ionic liquid solution and subjected to vacuum pressure treatment to obtain the parameters of the vacuum environment during the impregnation process: vacuum degree of 0.1 MPa, impregnation temperature of 100℃, and treatment time under vacuum conditions of 45 min.

[0106] After removing the filtrate from the impregnated sheet, it is wrapped with a pre-set film to form a molded sheet, which is then placed in a hot press for hot pressing. The hot press is set to a temperature of 165°C and a pressure of 3 MPa. The hot pressing time is 15 minutes. The film is a polytetrafluoroethylene (PTFE) film.

[0107] In the step of immersing the hot-pressed board in deionized water for displacement treatment under constant temperature conditions to obtain all-wood fiberboard, the temperature of the deionized water is 25°C and controlled by a water bath. The total extraction time is 300 minutes, with the deionized water being changed every 20 minutes for the first 20 minutes, and then every 60 minutes after 120 minutes.

[0108] In the step of placing a whole wood fiberboard into a molding mold and then placing it in a hot press for densification and shaping to obtain a molded board, the molding time is 20 minutes, the set pressure of the hot press is 5 MPa, and the set temperature of the press is 165°C. Example 3

[0109] This embodiment provides a whole wood fiberboard, which is prepared by the wood fiber product preparation method in the above embodiment 1. Specifically, the wood board in this embodiment has a thickness of 2mm. The wood board is a veneer with a thickness of 2mm formed by slicing fast-growing logs. After drying, the quality reaches a constant level, and the thickness of the veneer is ensured to be uniform with an error controlled within ±0.1mm.

[0110] The above ionic liquid solution is a compound of 1-butyl-3-methylimidazolium chloride and polyethylene glycol in a ratio of 40:60.

[0111] After drying, the wood-based panels are impregnated in a pre-set ionic liquid solution under vacuum pressure. The vacuum environment parameters for the impregnation process are as follows: vacuum degree 0.1 MPa, impregnation temperature 120℃, and processing time under vacuum conditions 30 min. The hot press is set to a temperature of 150℃ and a pressure of 5 MPa.

[0112] After removing the filtrate from the impregnated sheet, it is wrapped with a pre-set film to form a molded sheet, which is then placed in a hot press for hot pressing. The hot pressing process takes 30 minutes. The temperature of the deionized water is 25°C and is controlled by a water bath. The total extraction time is 30 minutes, with the deionized water changed every 5 minutes. The film is a polytetrafluoroethylene (PTFE) membrane.

[0113] In the step of placing a whole wood fiberboard into a molding mold and then placing it in a hot press for densification and shaping to obtain a molded board, the molding time is 10 minutes, the set pressure of the hot press is 10 MPa, and the set temperature is 180°C.

[0114] Comparative Example 1

[0115] This embodiment provides a wood-based panel, which is produced by slicing and drying fast-growing timber without any treatment.

[0116] Table 1 Mechanical performance parameters of each embodiment

[0117] No. Thickness / mm <![CDATA[Density / g / cm 3 > Compressive strength / MPa Elongation at break / % Initial elastic modulus / GPa Comparative Example 1 1.20 0.75 96.1 8.5 3.4 Example 1 0.47 1.22 147.1 9.2 6.2 Example 2 0.59 1.13 130.5 9.1 6.1 Example 3 0.87 0.91 107.4 9.5 5.9

[0118] Based on the above Table 1 and Figures 3 to 6 It can be seen that in Examples 1 to 3, the use of molten salt solvent and co-solvent as ionic liquid solutions to impregnate and hot-press the wood-based panels can achieve the dissolution of some, especially non-wood components, in the wood-based panels. Then, during the extraction process with deionized water, the molten salt solvent and co-solvent are replaced, which can achieve the recombination of the dissolved parts, especially the wood parts, in the veneer structure. This not only enhances the plasticity of the prepared all-wood fiberboard, but also improves the anisotropy of the all-wood fiberboard. The plasticity is used to achieve densification, while improving the mechanical properties of the wood-based panels. Moreover, cracks are not easily generated during the hot-pressing process, so as to facilitate the subsequent preparation of all-wood cellulose composite products with better mechanical properties.

[0119] Furthermore, after subsequent molding and cooling treatment, the mechanical properties of the aforementioned all-wood fiberboard can be further improved. For example, the compressive strength, elongation at break, and initial modulus of elasticity can all be further improved. For instance, the average initial modulus of elasticity is greater than 5.9 GPa, the elongation at break is greater than 9.1%, and the compressive strength is greater than 100 MPa.

[0120] Therefore, given the many possible implementations applicable to the disclosed principles, it should be recognized that the above implementations are merely examples and should not be considered as a limitation of scope. Consequently, we reserve all rights to the subject matter disclosed herein, including the right to claim protection for any and all combinations thereof, including but not limited to all matters within the scope and spirit of the following claims.

Claims

1. A method for preparing a wood fiber product, characterized in that, Includes the following steps: Obtain wood-based panels of a predetermined thickness, which is 1.9–2.1 mm. After drying, the wood-based panels are impregnated in a pre-defined ionic liquid solution under vacuum pressure to obtain impregnated panels. The ionic liquid solution comprises at least the following components: Molten salt solvents and co-solvents; After removing the filtrate from the impregnated board, it is wrapped with a pre-set film to form a board to be molded. Then, it is placed in a pre-set temperature and pre-set pressure environment for processing to obtain a hot-pressed board. The hot-pressed board is placed in a cleaning solution for displacement treatment to obtain an all-wood fiberboard. The ratio of the molten salt solvent to the co-solvent is 10:90 to 40:

60. The molten salt solvent comprises any one or a combination of two or more of 1-butyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium chloride, 1-allyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium acetate, 1-butyl-3-methylimidazolium acetate, or 1-allyl-3-methylimidazolium acetate; the co-solvent is any one or a combination of two or more of ethylene glycol, polyethylene glycol, dimethyl sulfoxide, and N,N-dimethylformamide. The step of drying the wood-based board and then impregnating it in a pre-set ionic liquid solution under vacuum pressure to obtain the impregnated board includes: After the wood-based board is dried, it is immersed in an ionic liquid solution at a preset immersion temperature of 80-120°C. The impregnated wood board is obtained by placing the ionic liquid solution impregnated with the wood board under a vacuum environment for at least 30 to 60 minutes.

2. The method for preparing wood fiber products according to claim 1, characterized in that, The steps for obtaining the wood board of the preset thickness include: Fast-growing timber is rotary-cut or planed to form the wood-based panels.

3. The method for preparing wood fiber products according to claim 1, characterized in that, The steps of removing the filtrate from the impregnated sheet, wrapping it with a pre-set film to form a molded sheet, and then processing it under a pre-set temperature and pre-set pressure to obtain a hot-pressed sheet include: After removing the filtrate from the impregnated board, it is wrapped with a pre-set film to form a board to be molded and then placed in a hot press. The sheet material to be molded is subjected to hot pressing in the hot press at a set temperature of 150-180°C and a set pressure of 0.5-5 MPa for at least 10-30 minutes to obtain the hot-pressed sheet material.

4. The method for preparing wood fiber products according to claim 1, characterized in that, The step of immersing the hot-pressed board in a cleaning solution for displacement treatment to obtain all-wood fiberboard includes: Prepare the cleaning solution using deionized water or ethanol, and keep the temperature of the cleaning solution within the range of 20°C to 26°C. The hot-pressed board is immersed in the cleaning solution for extraction for at least 30 to 720 minutes to obtain the all-wood fiberboard.

5. The method for preparing wood fiber products according to claim 4, characterized in that, The step of immersing the hot-pressed board in a cleaning solution for displacement treatment to obtain an all-wood fiberboard further includes: One or more of the aforementioned all-wood fiberboards are placed into a molding mold and then placed in a hot press for densification and shaping treatment to obtain a molded board. The densification and shaping treatment is performed at a pressure of at least 0.5 to 10 MPa, a temperature of 150 to 180°C, and a time of 10 to 30 minutes. The molded board is cooled to obtain an all-wood fiber molded board.

6. The method for preparing wood fiber products according to claim 3, characterized in that, The coating is a polytetrafluoroethylene (PTFE) film.

7. A wood fiber product, characterized in that, The wood fiber product is prepared by the method described in any one of claims 1 to 6.

Images