Mildew-proof and moisture-proof wood board for furniture and preparation method thereof

Abstract

The present application relates to the technical field of chemical and physical treatment of natural materials such as reed stalks, rice stalks, wheat stalks and corn stalks, and particularly relates to a furniture-use mildew-proof and moisture-proof wood-based panel and a preparation method thereof. The natural material is split longitudinally and the core is separated to form a natural material unit having a continuous outer skin side, a fiber bundle exposed side, longitudinal fiber bundles and a through longitudinal channel; first and second penetration zones are formed on both sides in staggered communication, and a first treatment liquid and a second treatment liquid are used to sequentially and through-impregnate in opposite directions, and a composite modified layer is formed through limited thickness heat curing; the modified natural material unit is then cross-laid, glued with wood veneers, hot-pressed into a panel, and after cutting, supplementary impregnation, heat curing and port sealing are performed along the through longitudinal channel to obtain the furniture-use mildew-proof and moisture-proof wood-based panel.

Description

Technical Field

[0001] This invention relates to the field of chemical and physical treatment technology of natural materials such as reed stalks, rice stalks, wheat stalks and corn stalks, and particularly to a mildew-proof and moisture-proof wood board for furniture and its preparation method. Background Technology

[0002] Natural materials such as reed stalks, rice straw, wheat straw, and corn stalks have longitudinal fiber bundles and internal channels extending along their length. After splitting, drying, gluing, oriented laying, and hot pressing, they can be used as core materials for wood-based panels used in furniture. Current technology typically involves longitudinally splitting, cracking, or flattening these natural materials to expose the internal fiber surfaces. Adhesives are then applied to the treated materials, and the panels are oriented and hot-pressed to form boards. To reduce the possibility of moisture absorption and mold growth during use, the natural materials can be soaked, sprayed, or mixed with anti-mold and moisture-proofing agents before laying or hot pressing.

[0003] For example, the international patent application WO1999004943A1, published by the World Intellectual Property Organization on February 4, 1999, discloses a straw structure board. The technical solution disclosed in this international patent application involves longitudinally splitting wheat straw, rice straw, or straw materials with a similar structure so that the inner and outer surfaces of the straw material can contact an adhesive. The split straw materials are then oriented, adhesive is applied, and the boards are pressed together. The resulting straw structure board can also serve as a core layer between two lignocellulose outer layers. The technical solution disclosed in this international patent application preserves the fibrous structure of the straw material extending along its length, and forms the core layer of the board through longitudinal splitting and oriented laying.

[0004] The aforementioned prior art mainly improves the contact conditions between natural materials and adhesives by longitudinally slicing them to expose their internal surfaces. For natural materials with a continuous outer skin, longitudinal fiber bundles, and internal channels, when it is necessary to retain the through longitudinal channels extending along the length direction, surface spraying, overall immersion, or adhesive mixing are used. The anti-mildew and moisture-proof treatment medium mainly enters from the outer surface of the natural material or the slit location, making it difficult to perform directional treatment on the interior of the natural material along the through longitudinal channels. Furthermore, the treatment medium may exhibit distribution differences between the channel entrance section and the internal section of the channel.

[0005] Furthermore, after natural materials are laid, glued, and hot-pressed to form slabs, they usually need to be cut to size and drilled, grooved, or tenoned during furniture making. These processes expose the original longitudinal channels within the natural material at the edges or processed areas. When edge banding materials or edge banding strips are applied to the edges, the treatment is mainly concentrated on the surface of the edge and the ports of the longitudinal channels, making it difficult to supplement the treatment of the channel sections extending into the board from these ports.

[0006] Therefore, the main technical problem that the existing technology needs to solve is: how to allow the anti-mildew and moisture-proof treatment medium to enter the internal longitudinal channels of the natural material while preserving the longitudinal fiber bundles and through longitudinal channels, and to supplement the treatment of the channel sections that are re-exposed after the board is cut. Summary of the Invention

[0007] To overcome the aforementioned technical deficiencies, the present invention aims to provide a mold- and moisture-proof wood-based panel for furniture and its preparation method. The present invention establishes penetration zones on the continuous outer skin side and exposed fiber bundle side of the natural material unit, which are connected to and staggered along the longitudinal direction of the through-flow channels. Two treatment liquids are then sequentially applied in opposite directions to impregnate the material and undergo limited-thickness thermosetting to form a composite modified layer. Simultaneously, after the panel is cut, additional impregnation, thermosetting, and port sealing are performed along the through-flow channels, thereby providing mold and moisture protection to the interior of the natural material and the re-exposed channel sections after cutting.

[0008] This invention discloses a method for preparing mildew-proof and moisture-proof wood-based panels for furniture, comprising the following steps:

[0009] At least one of the following natural materials—reed stalks, rice stalks, wheat stalks, and corn stalks—is longitudinally split and the pith is separated to create a natural material unit with a continuous outer skin side, an exposed fiber bundle side, longitudinal fiber bundles, and a through longitudinal channel.

[0010] A first permeable zone is formed on the continuous outer skin side, and a second permeable zone is formed on the exposed fiber bundle side. The first and second permeable zones are respectively connected to the through longitudinal channel, and the first and second permeable zones are staggered along the length direction of the natural material unit.

[0011] The natural material unit is loaded into a double-cavity impregnation fixture, and the first treatment solution containing chitosan and citric acid flows from the exposed side of the fiber bundle through the second permeation zone into the through longitudinal channel and flows out from the first permeation zone; the natural material unit that has completed the first treatment solution impregnation is controlled to allow the second treatment solution containing tannic acid and calcium lactate to flow in the reverse direction from the continuous outer skin side through the first permeation zone into the through longitudinal channel and flow out from the second permeation zone;

[0012] The natural material unit, which has been impregnated by the first treatment liquid and the second treatment liquid in sequence, is subjected to limited-thickness thermosetting to form a composite modified layer on the inner wall of the first penetration zone, the second penetration zone and the through longitudinal channel, thereby obtaining the modified natural material unit.

[0013] Modified natural material units are laid out as a first natural material core layer and a second natural material core layer, with the longitudinal fiber bundles of the first and second natural material core layers arranged to cross each other, and the continuous outer skin sides of the first and second natural material core layers facing each other; wood veneers are glued to the outside of the first and second natural material core layers, and the boards are formed by pre-pressing, segmented hot pressing and cooling.

[0014] The board blank is cut to a fixed length. Negative pressure is applied to the longitudinal channel formed by the cut first edge. The first treatment liquid and the second treatment liquid are sequentially introduced from the second edge opposite to the first edge, so that the first treatment liquid and the second treatment liquid can penetrate and replenish the longitudinal channel. Then, the longitudinal channel is heat-cured and a closed structure is formed at the port of the longitudinal channel to obtain a mildew-proof and moisture-proof wood board for furniture.

[0015] Preferably, the first permeation zone includes a plurality of first inclined grooves extending laterally through longitudinal channels from the continuous outer skin, and the second permeation zone includes a plurality of second inclined grooves extending laterally through longitudinal channels from the exposed fiber bundle side; the first and second inclined grooves are alternately arranged along the length direction of the natural material unit, and the angle between the projections of the first and second inclined grooves on the same projection plane perpendicular to the thickness direction of the natural material unit is 60° to 120°, and fiber bridges extending continuously along the longitudinal fiber bundle are retained between adjacent first and second inclined grooves.

[0016] Preferably, the dual-cavity impregnation fixture includes a first clamping plate, a second clamping plate, a first sealing frame, a second sealing frame, a first sealing cavity, and a second sealing cavity; the first clamping plate is attached to the exposed side of the fiber bundle, and the first sealing frame surrounds the second permeation area and together with the first clamping plate forms the first sealing cavity; the second clamping plate is attached to the continuous outer skin side, and the second sealing frame surrounds the first permeation area and together with the second clamping plate forms the second sealing cavity; the first sealing cavity and the second sealing cavity are respectively connected to the corresponding liquid supply pipeline, pressure regulating pipeline, and liquid collection pipeline, and the pipelines corresponding to the first sealing cavity and the pipelines corresponding to the second sealing cavity are independent of each other.

[0017] Preferably, the first treatment liquid comprises, by mass percentage, 0.8% to 1.6% chitosan, 0.5% to 1.2% citric acid, and the balance water; the first treatment liquid is introduced into the first sealed cavity, and a positive pressure of 0.35 to 0.65 MPa is applied in the first sealed cavity, while a negative pressure of -0.075 to -0.095 MPa is applied in the second sealed cavity; when the mass concentration of chitosan in the collection pipeline connected to the second sealed cavity is 20% to 40% of the mass concentration of chitosan in the first treatment liquid, the natural material unit is controlled to ensure that the amount of the first treatment liquid retained in the natural material unit is 12% to 22% of the oven-dry mass of the natural material unit.

[0018] Preferably, the second treatment solution comprises 0.6% to 1.4% tannic acid, 0.3% to 0.9% calcium lactate, and the balance water by mass percentage. After controlling the first treatment solution, the second treatment solution is introduced into the second sealed cavity, and a positive pressure of 0.30 to 0.60 MPa is applied in the second sealed cavity, while a negative pressure of -0.075 to -0.095 MPa is applied in the first sealed cavity. When the mass concentration of tannic acid in the collection pipeline connected to the first sealed cavity is 25% to 50% of the mass concentration of tannic acid in the second treatment solution, and the absolute value of the difference in tannic acid mass concentration obtained from two adjacent measurements is 0 to 5 percentage points, the impregnation with the second treatment solution is completed.

[0019] Preferably, the thickness-limited thermosetting includes: clamping a natural material unit, which has been sequentially impregnated with a first treatment liquid and a second treatment liquid, between a first breathable thickness-limiting plate and a second breathable thickness-limiting plate, and maintaining it at 55-70°C and 70%-90% relative humidity for 20-40 minutes; introducing dry hot air at 105-125°C into the through longitudinal channel, and alternately switching between a first flow direction with the first permeation zone as the air inlet and the second permeation zone as the air outlet and a second flow direction with the second permeation zone as the air inlet and the first permeation zone as the air outlet; subsequently maintaining it at 130-150°C for 5-15 minutes, and adjusting the moisture content of the natural material unit to 6%-10%.

[0020] Preferably, the longitudinal channels are divided into multiple channel groups according to their arrangement in the width direction of the natural material unit. During the thickness-limited thermosetting process, the inlet pressure, outlet pressure, and outlet air moisture content of each channel group under the current dry hot air flow direction are detected respectively. The channel groups with an inlet pressure-outlet pressure difference of 0.02-0.08 MPa and an absolute value of the difference in outlet air moisture content between two adjacent measurements of 0-2 g / kg are switched to the heat preservation state. The first flow direction and the second flow direction are alternately switched for the channel groups in the dry hot air input state until all channel groups are switched to the heat preservation state.

[0021] Preferably, the modified natural material units constituting the first natural material core layer are arranged in parallel to each other, and the two ends of each through longitudinal channel in the first natural material core layer are respectively connected to the first set of opposite edges of the slab; the modified natural material units constituting the second natural material core layer are arranged in parallel to each other, and the two ends of each through longitudinal channel in the second natural material core layer are respectively connected to the second set of opposite edges of the slab; the extension direction of the first set of opposite edges and the extension direction of the second set of opposite edges form an angle of 70° to 90°, the longitudinal fiber bundles of the first natural material core layer and the second natural material core layer form an angle of 70° to 90°, and the projections of the first permeation zone in the first natural material core layer and the first permeation zone in the second natural material core layer in the thickness direction are staggered.

[0022] Preferably, a plurality of bonding windows and a plurality of hydrophobic isolation areas are respectively provided on the continuous outer skin side of the first natural material core layer and the second natural material core layer facing each other, and the bonding windows and hydrophobic isolation areas are alternately distributed on the plate surface of each continuous outer skin side; each hydrophobic isolation area is arranged around the corresponding first penetration area and coated with a hydrophobic treatment liquid containing n-octyltriethoxysilane and carnauba wax; the bonding windows provided in the first natural material core layer and the bonding windows provided in the second natural material core layer correspond to each other in the plate thickness direction, and the corresponding bonding windows are filled with adhesive.

[0023] Preferably, before segmented hot pressing, edge guide boxes are installed on the first and second sets of opposite edges, respectively, and each edge guide box is equipped with a connecting valve; segmented hot pressing includes a channel venting stage, a core layer compaction stage, and a bonding and shaping stage performed sequentially; in the channel venting stage, negative pressure is applied sequentially through the edge guide boxes corresponding to the longitudinal channels of the first natural material core layer and the edge guide boxes corresponding to the longitudinal channels of the second natural material core layer; in the core layer compaction stage, each longitudinal channel is kept in communication with the corresponding edge guide box; in the bonding and shaping stage, the ports of each longitudinal channel are sealed through the connecting valve, and the slab is subjected to pressure-holding heat curing.

[0024] Preferably, the segmented hot pressing uses a partitioned hot pressing plate with multiple independent pressurization zones. Each edge guide box is divided into 3 to 8 independent guide cavities along its corresponding edge. The projection areas of each independent pressurization zone and the corresponding independent guide cavity on the plate surface correspond. The condensate flowing out of each independent guide cavity is collected separately, and the mass of the condensate output from each independent guide cavity is detected every 30 to 60 seconds. After condensate is output from each independent guide cavity, the hot pressing pressure of the corresponding independent pressurization zone is adjusted according to the mass of the condensate output from each independent guide cavity, so that the ratio of the maximum condensate mass to the minimum condensate mass in the same edge guide box is 1 to 1.20, and then the bonding and shaping stage begins.

[0025] Preferably, the through-hole supplement impregnation includes: setting a first partition impregnation assembly at a first set of opposite sides, the first partition impregnation assembly including a first supply box and a first suction box respectively disposed at two sides of the first set of opposite sides; sequentially inputting a first treatment liquid and a second treatment liquid into the through-hole longitudinal channel in the first natural material core layer through the first supply box, and applying negative pressure to the through-hole longitudinal channel in the first natural material core layer through the first suction box; setting a second partition impregnation assembly at a second set of opposite sides, the second partition impregnation assembly including a second supply box and a second suction box respectively disposed at two sides of the second set of opposite sides; sequentially inputting the first treatment liquid and the second treatment liquid into the through-hole longitudinal channel in the second natural material core layer through the second supply box, and applying negative pressure to the through-hole longitudinal channel in the second natural material core layer through the second suction box.

[0026] Preferably, according to the arrangement of the ports of each through longitudinal channel on the corresponding edge, the through longitudinal channels in the first and second natural material core layers are respectively divided into multiple supplementary impregnation channel groups; the first and second liquid supply boxes each include multiple liquid supply partition cavities corresponding one-to-one with the supplementary impregnation channel groups, and the first and second suction boxes each include multiple suction partition cavities corresponding one-to-one with the supplementary impregnation channel groups; a first treatment liquid is input into each supplementary impregnation channel group until the chitosan mass concentration in the corresponding suction partition cavity is equal to the first treatment liquid input into the corresponding liquid supply partition cavity. The chitosan mass concentration in the liquid is 15%–35%; after liquid control, the second treatment liquid is introduced until the tannic acid mass concentration in the corresponding suction compartment is 20%–45% of the tannic acid mass concentration in the second treatment liquid introduced into the corresponding supply compartment; after each alternating application of positive and negative pressure pulses, the corresponding first or second treatment liquid is introduced again and the chitosan mass concentration or tannic acid mass concentration in the corresponding suction compartment is detected; when the chitosan mass concentration and tannic acid mass concentration reach the corresponding range, the corresponding supplementary impregnation channel group is heat-cured.

[0027] Preferably, before drilling, grooving, or tenoning the anti-mildew and moisture-proof wood panels for furniture, the processing position is determined based on the projection position of the through longitudinal channels in the first and second natural material core layers on the board surface; after processing, a wooden sealing component that matches the contour of the processing area is installed on the processing area. The wooden sealing component has a liquid injection hole and multiple guide channels communicating with the liquid injection hole. The guide channels communicate with the through longitudinal channels exposed in the processing area; the first treatment liquid and the second treatment liquid are sequentially introduced through the liquid injection hole, so that the first treatment liquid and the second treatment liquid enter the through longitudinal channels exposed in the processing area through the guide channels; the processing area with the wooden sealing component is hot-pressed and cured, and a wax-containing sealing layer is formed around the wooden sealing component.

[0028] In view of this, a type of mold-resistant and moisture-proof wood-based panel for furniture is provided, wherein the mold-resistant and moisture-proof wood-based panel for furniture is prepared by the preparation method for mold-resistant and moisture-proof wood-based panels for furniture as described above. Compared with the prior art, the above technical solution has the following beneficial effects:

[0029] 1. This invention focuses on the directional treatment of the through longitudinal channels of natural materials. By forming a first and second permeation zones that are staggered and interconnected on the continuous outer skin side and the exposed fiber bundle side, the first and second treatment liquids can sequentially enter the interior of the natural material along the through longitudinal channels. Compared with surface spraying, overall immersion, or ordinary adhesive mixing methods, this invention can improve the adequacy of the anti-mildew and moisture-proof treatment medium in treating the internal pore sections of the natural material.

[0030] 2. In this invention, the first and second treatment solutions are sequentially impregnated in opposite directions, and after liquid control, a limited-thickness heat curing is performed, so that chitosan, citric acid, tannic acid and calcium lactate can form a composite modified layer in the first penetration zone, the second penetration zone and the inner wall of the longitudinal pores, thereby improving the moisture-proof and mildew-proof stability of the internal pores of the natural material unit.

[0031] 3. After the slab is cut to length, the present invention further impregnates, heat-cures, and seals the re-exposed longitudinal channels. This allows for post-treatment of the re-exposed channel sections at the cut edges, reducing the risk of moisture entering the slab through the cut ends and improving the moisture-proof performance of the slab edges.

[0032] 4. In this invention, modified natural material units are laid out as a first natural material core layer and a second natural material core layer, and the two layers of longitudinal fiber bundles are arranged to cross each other and the continuous outer skin sides are arranged to face each other. At the same time, a bonding window and a hydrophobic isolation area are set at the interface between the two sides. This can improve the water-blocking continuity of the core layer interface while maintaining the interlayer bonding connection, and improve the structural stability of the wood-based panels for furniture.

[0033] 5. This invention introduces the detection and control of channel group pressure, outlet air moisture content and edge guide condensate quality in the process of limited thickness thermosetting and segmented hot pressing. It can adjust the drying, venting and hot pressing shaping process of the through longitudinal channel in a zone, reducing the impact of local moisture content differences and uneven hot pressing venting on the forming quality of the board. Attached Figure Description

[0034] Figure 1 This is a flowchart illustrating the overall process for preparing anti-mildew and moisture-proof wood-based panels for furniture according to this application.

[0035] Figure 2 This is a flowchart illustrating the impregnation control process of the first and second treatment solutions during the bidirectional through-impregnation process of this application.

[0036] Figure 3This is a logic diagram for the switching of the drying hot airflow direction and the control of the channel group status during the thickness-limited thermosetting process of this application;

[0037] Figure 4 This is a flowchart illustrating the edge guide box exhaust, condensate detection, and hot pressing pressure regulation control during the segmented hot pressing process of this application.

[0038] Figure 5 A flowchart illustrating the process of impregnation, thermosetting, and port sealing of longitudinal channels after the sheet material of this application is cut;

[0039] Figure 6 This is a graph comparing the moisture-proof performance of the embodiments and comparative examples of this application. Detailed Implementation

[0040] The following description, in conjunction with the accompanying drawings, further illustrates a mildew- and moisture-proof wood-based panel for furniture and its preparation method. The following embodiments illustrate the feasible process of the preparation method and the relationship between the natural material unit, the through-flow longitudinal channel, the first penetration zone, the second penetration zone, the dual-cavity impregnation fixture, the first treatment liquid, the second treatment liquid, the thickness-limited thermosetting, the first natural material core layer, the second natural material core layer, the inner interface layer, the through-flow supplementary impregnation, and the port sealing layer. Those skilled in the art can adaptively adjust the specific parameters according to the type of natural material, the panel specifications, the furniture processing method, and the production equipment capacity without altering the aforementioned technical relationships.

[0041] like Figure 1 As shown, the preparation method includes steps such as natural material screening, natural material splitting, core-pith separation, penetration zone formation, bidirectional through-hole impregnation, thickness-limited thermosetting, core layer cross-laying, wood veneer gluing, segmented hot pressing, cooling and shaping, length-cutting, through-hole supplementary impregnation, supplementary thermosetting, and end sealing. The preparation method treats the through-hole longitudinal channels within the natural material, allowing the first and second treatment solutions to penetrate the interior of the natural material, and supplements the treatment of the re-exposed through-hole longitudinal channels after the board is cut.

[0042] At least one natural material selected from reed stalks, rice straw, wheat straw, and corn stalks is used as raw material. Before use, the natural materials are graded and screened to remove moldy, insect-infested, obviously cracked, or rotten ends, and then cut into stalk segments ranging from 200mm to 600mm in length. For applications such as furniture shelves, cabinet side panels, drawer bottoms, or furniture back panels, the natural materials can be cut into stalk segments ranging from 320mm to 480mm to form a stable first and second natural material core layer during subsequent installation.

[0043] After being rinsed with clean water, the natural material is pre-dried to achieve a moisture content of 8% to 14%. Subsequently, it is split along its length using a longitudinal splitting tool, and the core is separated using a scraping roller or flexible scraper to create natural material units. Each natural material unit has a continuous outer skin side, an exposed fiber bundle side, longitudinal fiber bundles, and a through longitudinal channel. The continuous outer skin side is formed by retaining the original outer skin of the natural material, the exposed fiber bundle side is formed after splitting and core separation, the longitudinal fiber bundles extend continuously along the length of the natural material unit, and the through longitudinal channel extends continuously along the length of the natural material unit. The width of the natural material unit can be controlled from 8 mm to 25 mm, and the thickness can be controlled from 1.5 mm to 4.0 mm.

[0044] A first permeation zone is formed on the continuous outer skin side of the natural material unit, and a second permeation zone is formed on the fiber bundle exposed side of the natural material unit. Both the first and second permeation zones are connected to the through longitudinal channel, and the first and second permeation zones are staggered along the length of the natural material unit. The first permeation zone includes a plurality of first inclined grooves extending from the continuous outer skin side to the through longitudinal channel, and the second permeation zone includes a plurality of second inclined grooves extending from the fiber bundle exposed side to the through longitudinal channel. The first and second inclined grooves can be formed using a micro-rotary blade, a micro-toothed pressure roller, or a low-power laser etching device. In one embodiment, a micro-toothed pressure roller is used to press the first and second inclined grooves from the continuous outer skin side and the fiber bundle exposed side, respectively, so that the first and second inclined grooves pass through the corresponding side surface layers and connect to the through longitudinal channel.

[0045] The width of the first inclined groove can be from 0.15 mm to 0.30 mm, and the width of the second inclined groove can also be from 0.15 mm to 0.30 mm. The extension depth of the first and second inclined grooves along the thickness direction of the natural material unit can be from 25% to 45% of the thickness of the natural material unit. The projection angle between the first and second inclined grooves on the same projection plane perpendicular to the thickness direction of the natural material unit is from 60° to 120°. A fiber bridge extending continuously along the longitudinal fiber bundle is maintained between adjacent first and second inclined grooves. The fiber bridge serves to maintain the continuous extension of the longitudinal fiber bundle along the length direction of the natural material unit and to provide the first and second permeation zones as local channels for the entry and exit of the treatment liquid.

[0046] like Figure 2As shown, after forming the first and second permeation zones, the natural material unit is loaded into the dual-cavity impregnation fixture. The dual-cavity impregnation fixture includes a first clamping plate, a second clamping plate, a first sealing frame, a second sealing frame, a first sealing cavity, and a second sealing cavity. The first clamping plate is attached to the exposed side of the fiber bundle, and the first sealing frame surrounds the second permeation zone and together with the first clamping plate forms the first sealing cavity; the second clamping plate is attached to the continuous outer skin side, and the second sealing frame surrounds the first permeation zone and together with the second clamping plate forms the second sealing cavity. Both the first and second sealing cavities are connected to corresponding liquid supply lines, pressure regulating lines, and liquid collection lines, respectively, and the lines corresponding to the first sealing cavity and the lines corresponding to the second sealing cavity are independent of each other. The first and second sealing frames can be made of acid- and alkali-resistant silicone, fluororubber, or air-inflatable elastic sealing strips. For reed stalks or corn stalks with a large outer surface curvature, when using air-inflatable elastic sealing strips, the first and second sealing frames can remain in contact with the surface of the natural material unit, reducing the short-circuit flow of the treatment liquid around the through-channels.

[0047] The first treatment solution comprises, by mass percentage, 0.8% to 1.6% chitosan, 0.5% to 1.2% citric acid, and the balance water. To prepare the first treatment solution, citric acid is first added to water to form an acidic solution, then chitosan is added and stirred until dissolved or uniformly dispersed. The second treatment solution comprises, by mass percentage, 0.6% to 1.4% tannic acid, 0.3% to 0.9% calcium lactate, and the balance water. To prepare the second treatment solution, tannic acid is first added to water and stirred until dissolved, then calcium lactate is added and stirring continues. The first and second treatment solutions are prepared separately and introduced into the through-type longitudinal channels at different impregnation stages.

[0048] During the first treatment liquid impregnation process, the first treatment liquid is introduced into the first sealed cavity, and a positive pressure of 0.35 MPa to 0.65 MPa is applied within the first sealed cavity. Simultaneously, a negative pressure of -0.075 MPa to -0.095 MPa is applied within the second sealed cavity, causing the first treatment liquid to flow from the exposed side of the fiber bundle through the second permeation zone into the longitudinal channel, and then out of the first permeation zone into the second sealed cavity. The chitosan mass concentration in the outflow liquid is detected through a collection pipe connected to the second sealed cavity. When the chitosan mass concentration in the collection pipe connected to the second sealed cavity is 20% to 40% of the chitosan mass concentration in the first treatment liquid, the introduction of the first treatment liquid is stopped, and the natural material unit is controlled to ensure that the amount of first treatment liquid retained in the natural material unit is 12% to 22% of the oven-dry mass of the natural material unit.

[0049] The first treatment liquid retention volume can be calculated according to formula (1):

[0050] (1)

[0051] in, This indicates the amount of the first-stage treatment solution retained, expressed as a percentage. This indicates the absolute dry mass of a unit of natural material, expressed in grams. The mass of the natural material unit after the first treatment liquid control is completed is expressed in grams. The oven-dry mass of the natural material unit is measured by drying the same batch of natural material units at 103℃±2℃ to constant weight. The mass of the natural material unit after the first treatment liquid control is obtained by weighing the natural material unit after the liquid control.

[0052] For example, if the oven-dry weight of the natural material unit is 1000g, and the weight of the natural material unit after the first treatment liquid control is 1170g, then the retention amount of the first treatment liquid is:

[0053]

[0054] If the calculated retention rate of the first treatment solution is between 12% and 22%, then reverse impregnation with the second treatment solution can be performed.

[0055] After controlling the first treatment solution, the second treatment solution is introduced into the second sealing cavity, and a positive pressure of 0.30 MPa to 0.60 MPa is applied inside the second sealing cavity. Simultaneously, a negative pressure of -0.075 MPa to -0.095 MPa is applied inside the first sealing cavity, causing the second treatment solution to flow backward from the continuous outer skin side through the first permeation zone into the through longitudinal channel, and then out through the second permeation zone into the first sealing cavity. The tannic acid concentration in the outflow is detected through a collection pipe connected to the first sealing cavity. When the tannic acid concentration in the collection pipe connected to the first sealing cavity is 25% to 50% of the tannic acid concentration in the second treatment solution, and the absolute value of the difference in tannic acid concentration between two consecutive measurements is 0 to 5 percentage points, the impregnation with the second treatment solution is complete.

[0056] The concentration ratio of the effluent side treatment liquid can be calculated according to formula (2):

[0057] (2)

[0058] in, This indicates the concentration ratio of the outflow treatment solution, expressed as a percentage. This indicates the mass concentration of the corresponding detected component in the collection pipeline, expressed in grams per liter. This indicates the mass concentration of the corresponding detected component in the input-side processing solution, expressed in grams per liter. The mass concentration of chitosan can be determined using ultraviolet spectrophotometry or the total organic carbon method, while the mass concentration of tannic acid can be determined using ultraviolet spectrophotometry or high-performance liquid chromatography.

[0059] For example, if the tannic acid concentration in the second treatment solution is 10.0 g / L, and the tannic acid concentration in the collection pipe connected to the first sealed cavity is 3.8 g / L, then the concentration ratio of the outflowing treatment solution is:

[0060]

[0061] The calculated effluent concentration ratio is within the range of 25% to 50%. If the tannic acid concentrations obtained from two consecutive measurements are 3.7 g / L and 3.8 g / L, respectively, and converted to an input concentration of 10.0 g / L, the absolute value of the difference in tannic acid concentration between the two consecutive measurements is 1.0 percentage point, which meets the criteria for completing the second treatment solution impregnation.

[0062] like Figure 3 As shown, after sequential impregnation with the first and second treatment solutions, the natural material unit undergoes thickness-limited thermosetting. The thickness-limited thermosetting includes three consecutive stages. In the first stage, the natural material unit, sequentially impregnated with the first and second treatment solutions, is sandwiched between a first and a second breathable thickness-limiting plate and maintained at 55°C to 70°C and 70% to 90% relative humidity for 20 to 40 minutes. In the second stage, dry hot air at 105°C to 125°C is introduced into the longitudinally penetrating channel, alternating between a first flow direction with the first permeation zone as the air inlet and the second permeation zone as the air outlet, and a second flow direction with the second permeation zone as the air inlet and the first permeation zone as the air outlet. In the third stage, the temperature is maintained at 130°C to 150°C for 5 to 15 minutes, and the moisture content of the natural material unit is adjusted to 6% to 10%, forming a composite modified layer between the first permeation zone, the second permeation zone, and the inner wall of the longitudinally penetrating channel, resulting in the modified natural material unit.

[0063] During the thickness-limited thermosetting process, the longitudinal channels can be divided into multiple channel groups according to their arrangement along the width of the natural material unit. The inlet pressure, outlet pressure, and outlet air moisture content of each channel group under the current dry hot air flow direction are measured. The inlet pressure can be measured using a pressure sensor installed on the main inlet pipe or the branch inlet pipe of each zone; the outlet pressure can be measured using a pressure sensor installed on the main outlet pipe or the branch outlet pipe of each zone; and the outlet air moisture content can be calculated using humidity and temperature sensors installed at the outlet end. Channel groups with an inlet-to-outlet pressure difference of 0.02 MPa to 0.08 MPa and an absolute value of the difference in outlet air moisture content between two consecutive measurements of 0 g / kg to 2 g / kg are switched to the heat preservation state. For channel groups in the dry hot air input state, the first and second flow directions are alternately switched until all channel groups are switched to the heat preservation state.

[0064] The difference between the inlet pressure and the outlet pressure can be calculated using formula (3):

[0065] (3)

[0066] in, This represents the difference between the inlet and outlet pressures, expressed in megapascals (MPA). This indicates the inlet pressure of the current channel group, in megapascals (MPa). This represents the outlet pressure of the current channel group, in megapascals (MPa). For example, if the inlet pressure of a channel group is 0.118 MPa and the outlet pressure is 0.072 MPa, then the difference between the inlet and outlet pressures is:

[0067]

[0068] The calculated difference between the inlet and outlet pressures is within the range of 0.02 MPa to 0.08 MPa. If the moisture content of the outlet air in two adjacent measurements is 12.4 g / kg and 11.2 g / kg respectively, then the absolute value of the difference in moisture content between the two adjacent measurements is 1.2 g / kg, and the corresponding channel group can be switched to the heat preservation state.

[0069] Subsequently, the obtained modified natural material units are laid out as a first natural material core layer and a second natural material core layer, respectively. Multiple modified natural material units constituting the first natural material core layer are arranged parallel to each other, with the ends of each through-channel in the first natural material core layer connected to the first set of opposite edges of the slab. Similarly, multiple modified natural material units constituting the second natural material core layer are arranged parallel to each other, with the ends of each through-channel in the second natural material core layer connected to the second set of opposite edges of the slab. The extension directions of the first set of opposite edges and the second set of opposite edges form an angle of 70° to 90°, and the longitudinal fiber bundles of the first and second natural material core layers form an angle of 70° to 90°. The projections of the first permeable zone in the first natural material core layer and the first permeable zone in the second natural material core layer in the thickness direction are staggered.

[0070] Multiple bonding windows and multiple hydrophobic isolation zones are respectively provided on the continuous outer skin sides of the first and second natural material core layers facing each other. The bonding windows and hydrophobic isolation zones are alternately distributed on the surface of each continuous outer skin side. The hydrophobic isolation zones are arranged around the corresponding first penetration zone and coated with a hydrophobic treatment liquid containing n-octyltriethoxysilane and carnauba wax. The bonding windows in the first and second natural material core layers correspond to each other in the thickness direction, and the corresponding bonding windows are filled with adhesive. The hydrophobic treatment liquid may include 1% to 3% n-octyltriethoxysilane emulsion, 3% to 8% carnauba wax emulsion, and the balance being water by mass percentage. The adhesive may be an isocyanate adhesive, a modified urea-formaldehyde resin adhesive, or a formaldehyde-free plant-based adhesive. By using an alternating distribution of bonding windows and hydrophobic isolation zones, both a bonding connection area and a hydrophobic isolation area surrounding the first penetration zone can be simultaneously provided between the continuous outer skin sides.

[0071] During installation, wood veneers are glued to the outer sides of the first and second natural material core layers to obtain a hot-pressed board blank. The wood veneers can be poplar veneer, eucalyptus veneer, birch veneer, or bamboo veneer, with a thickness ranging from 0.6 mm to 1.5 mm. In the hot-pressed board blank, the continuous outer skin sides of the first and second natural material core layers face each other, and the exposed fiber bundle sides of the first and second natural material core layers face the corresponding wood veneers. After installation, the board blank is pre-pressed; the pre-pressing pressure can be from 0.3 MPa to 0.6 MPa, and the pre-pressing time can be from 3 min to 8 min.

[0072] like Figure 4 As shown, before segmented hot pressing, edge guide boxes are installed on the first and second sets of opposite edges, respectively, and each edge guide box is equipped with a connecting valve. Segmented hot pressing includes a sequential venting stage, a core layer compaction stage, and a bonding and shaping stage. In the venting stage, negative pressure is sequentially applied through the edge guide boxes corresponding to the longitudinal vents of the first natural material core layer and the edge guide boxes corresponding to the longitudinal vents of the second natural material core layer, causing water vapor and free processing liquid vapor in the longitudinal vents to be discharged along the edge guide boxes. In the core layer compaction stage, each longitudinal vent is kept connected to its corresponding edge guide box, allowing the gas generated during hot pressing to be released along the longitudinal vents. In the bonding and shaping stage, the ports of each longitudinal vent are sealed using the connecting valves, and the slab is subjected to pressure-holding heat curing.

[0073] In one specific embodiment, the temperature during the venting stage is 85°C to 105°C, the pressure is 0.5MPa to 0.9MPa, and the time is 60s to 150s; the temperature during the core layer compaction stage is 125°C to 145°C, the pressure is 1.4MPa to 2.2MPa, and the time is 4min to 8min; the temperature during the gluing and shaping stage is 135°C to 155°C, the pressure is 1.2MPa to 1.8MPa, and the time is 3min to 6min. The aforementioned parameters can be adjusted according to the thickness of the wood veneer, the thickness of the natural material core layer, and the type of adhesive.

[0074] To achieve zoned hot pressing control, segmented hot pressing can employ a zoned hot pressing plate with multiple independent pressurization zones. Each edge guide box is divided into 3 to 8 independent guide chambers along its corresponding edge, with each independent pressurization zone corresponding to the projected area of ​​its respective independent guide chamber on the plate surface. Condensate flowing from each independent guide chamber is collected, and the mass of condensate output from each independent guide chamber is measured every 30 to 60 seconds. After condensate output has occurred in each independent guide chamber, the hot pressing pressure of the corresponding independent pressurization zone is adjusted based on the condensate mass output from each independent guide chamber, ensuring that the ratio of the maximum to minimum condensate mass in the same edge guide box is 1 to 1.20, and then the process proceeds to the bonding and setting stage.

[0075] The mass ratio of condensate can be calculated according to formula (4):

[0076] (4)

[0077] in, This represents the ratio of the maximum condensate mass to the minimum condensate mass within the same edge guide box. This indicates the maximum mass of condensate output from each independent flow chamber within the same edge flow box, expressed in grams. This represents the minimum condensate mass output from each independent flow channel within the same edge flow channel, expressed in grams. For example, if the maximum condensate mass output from the eight independent flow channels in an edge flow channel is 6.0g and the minimum condensate mass is 5.2g, then the condensate mass ratio is:

[0078]

[0079] If the calculated condensate mass ratio is in the range of 1 to 1.20, the product can proceed to the bonding and setting stage.

[0080] After segmented hot pressing, the board blank is cooled and shaped. Cooling and shaping can be carried out under a pressure of 0.3MPa to 0.7MPa, and the pressure is released after the center temperature of the board blank reaches 40℃ to 60℃. Subsequently, the board blank is cut to size to form the initial specification board of the mold-proof and moisture-proof wood-based panel for furniture. Since the through longitudinal channels in the first and second natural material core layers will be re-exposed at the edges of the board after cutting, further through-impregnation is performed.

[0081] like Figure 5 As shown, the through-hole replenishment impregnation includes replenishment treatment of the first natural material core layer and the second natural material core layer respectively. For the first natural material core layer, a first partitioned impregnation assembly is provided at the first set of opposite edges. The first partitioned impregnation assembly includes a first supply box and a first suction box respectively disposed at two edges of the first set of opposite edges. A first treatment liquid and a second treatment liquid are sequentially introduced into the through-hole longitudinal channels of the first natural material core layer through the first supply box, and a negative pressure is applied to the through-hole longitudinal channels of the first natural material core layer through the first suction box. For the second natural material core layer, a second partitioned impregnation assembly is provided at the second set of opposite edges. The second partitioned impregnation assembly includes a second supply box and a second suction box respectively disposed at two edges of the second set of opposite edges. A first treatment liquid and a second treatment liquid are sequentially introduced into the through-hole longitudinal channels of the second natural material core layer through the second supply box, and a negative pressure is applied to the through-hole longitudinal channels of the second natural material core layer through the second suction box.

[0082] During the through-hole replenishment impregnation process, the through-holes in the first and second natural material core layers are divided into multiple replenishment impregnation channel groups according to the arrangement of the ports of each through-hole on the corresponding edges. The first and second supply boxes each include multiple supply compartments corresponding to one-to-one replenishment impregnation channel groups, and the first and second suction boxes each include multiple suction compartments corresponding to one-to-one replenishment impregnation channel groups. A first treatment solution is introduced into each replenishment impregnation channel group until the chitosan mass concentration in the corresponding suction compartment is 15% to 35% of the chitosan mass concentration in the first treatment solution introduced into the corresponding supply compartment. After liquid control, a second treatment solution is introduced until the tannic acid mass concentration in the corresponding suction compartment is 20% to 45% of the tannic acid mass concentration in the second treatment solution introduced into the corresponding supply compartment.

[0083] For supplementary impregnation channel groups that do not reach the aforementioned chitosan or tannic acid concentration ranges, after each alternating application of positive and negative pressure pulses, the corresponding first or second treatment solution is reintroduced, and the chitosan or tannic acid concentration in the corresponding suction chamber is detected. When the chitosan and tannic acid concentrations reach their respective ranges, the corresponding supplementary impregnation channel group is thermally cured. The positive pressure pulse can be 0.15 MPa to 0.35 MPa and last for 2 to 8 seconds, and the negative pressure pulse can be -0.040 MPa to -0.080 MPa and last for 2 to 8 seconds, with the alternation occurring 2 to 6 times. Thermal curing can be performed using hot air at 80°C to 105°C or using a hot press for 3 to 8 minutes. After thermal curing, a closed structure is formed at the port of the longitudinal channel. The closed structure may include a wax-containing sealing layer and a wooden edge banding strip. The wax-containing sealing layer enters the inside of the through longitudinal channel port and overlaps with the composite modified layer. The wooden edge banding strip covers the wax-containing sealing layer and the through longitudinal channel port.

[0084] Before drilling, grooving, or tenoning furniture-grade mildew-proof and moisture-proof wood panels, the processing location can be determined based on the projection position of the longitudinally penetrating channels in the first and second natural material core layers onto the panel surface. After processing, a wooden sealing component that matches the contour of the processed area is installed. The wooden sealing component has an injection hole and multiple guide channels communicating with the injection hole, which are connected to the exposed longitudinally penetrating channels of the processed area. The first and second treatment liquids are sequentially introduced through the injection hole, allowing them to enter the exposed longitudinally penetrating channels of the processed area via the guide channels. Subsequently, the processed area with the wooden sealing component is heat-pressed and cured, forming a wax-containing sealing layer around the periphery of the wooden sealing component. The wooden sealing component can be a wooden hole-sealing component, a wooden groove-shaped sealing component, or a wooden tenon-jointed sealing component, and its outer contour is adapted to the contour of the processed area formed by drilling, grooving, or tenoning.

[0085] To support implementation processes under different natural materials, different permeation zone structures, different impregnation pressures, different treatment solution concentrations, different thermosetting conditions, and different supplementary impregnation conditions, three specific embodiments are given below. Embodiment 1 uses values ​​near the lower limit of the main parameter range, Embodiment 2 uses the middle value of the main parameter range, and Embodiment 3 uses values ​​near the upper limit of the main parameter range. All three embodiments share a common process basis: natural material units, a first permeation zone, a second permeation zone, a through longitudinal channel, a dual-cavity impregnation fixture, a first treatment solution, a second treatment solution, thickness-limited thermosetting, a first natural material core layer, a second natural material core layer, segmented hot pressing, and through supplementary impregnation.

[0086] In Example 1, rice straw and wheat straw were selected as natural materials. The natural materials were cut into 200mm long segments, washed, and pre-dried to achieve a moisture content of 8%. Subsequently, the natural materials were split along their length, and the pith was separated to create natural material units with a width of 8mm and a thickness of 1.5mm. Each natural material unit has a continuous outer skin side, an exposed fiber bundle side, longitudinal fiber bundles, and through longitudinal channels. A first permeable zone is formed on the continuous outer skin side, and a second permeable zone is formed on the exposed fiber bundle side. The first permeable zone includes multiple first inclined grooves, and the second permeable zone includes multiple second inclined grooves. The first and second inclined grooves are alternately arranged along the length of the natural material unit. The projection angle between the first and second inclined grooves on the same projection plane perpendicular to the thickness direction of the natural material unit is 60°. Fiber bridges extending continuously along the longitudinal fiber bundles are preserved between adjacent first and second inclined grooves.

[0087] In Example 1, the first treatment solution comprises 0.8% chitosan, 0.5% citric acid, and 98.7% water by mass percentage. The first treatment solution is introduced into the first sealed cavity, where a positive pressure of 0.35 MPa is applied. Simultaneously, a negative pressure of -0.075 MPa is applied into the second sealed cavity, causing the first treatment solution to enter the longitudinal channel through the second permeation zone from the exposed side of the fiber bundle and flow out from the first permeation zone. When the chitosan mass concentration in the collection pipe connected to the second sealed cavity reaches 20% of the chitosan mass concentration in the first treatment solution, the introduction of the first treatment solution is stopped, and liquid control is implemented to ensure that the amount of first treatment solution retained in the natural material unit is 12% of the oven-dry mass of the natural material unit. The second treatment solution comprises 0.6% tannic acid, 0.3% calcium lactate, and 99.1% water by mass percentage. After controlling the first treatment solution, the second treatment solution is introduced into the second sealed cavity. A positive pressure of 0.30 MPa is applied inside the second sealed cavity, while a negative pressure of -0.075 MPa is applied inside the first sealed cavity. This causes the second treatment solution to flow backward from the continuous outer skin side through the first permeation zone into the through longitudinal channel and out through the second permeation zone. The impregnation with the second treatment solution is complete when the tannic acid concentration in the collection pipe connected to the first sealed cavity is 25% of the tannic acid concentration in the second treatment solution, and the absolute value of the difference in tannic acid concentration between two adjacent measurements is 5 percentage points.

[0088] In Example 1, natural material units, sequentially impregnated with a first treatment solution and a second treatment solution, are sandwiched between a first and a second breathable thickness limiting plate and maintained at 55°C and 70% relative humidity for 20 minutes. Then, dry hot air at 105°C is introduced into the longitudinally penetrating channels, alternating between the first and second flow directions three times. Subsequently, the mixture is maintained at 130°C for 5 minutes, and the moisture content of the natural material units is adjusted to 10%, resulting in modified natural material units. These modified natural material units are then laid as a first natural material core layer and a second natural material core layer, with the longitudinal fiber bundles of the first and second natural material core layers forming a 70° angle, and the continuous outer skin sides of the two layers facing each other. Subsequently, wood veneers are glued to the outer sides of both layers, and the resulting boards are pre-pressed, segmented hot-pressed, and cooled to solidify. During the segmented hot pressing process, the temperature for the venting stage of the ducts is 85℃, the pressure is 0.5MPa, and the time is 60s; the temperature for the core layer compaction stage is 125℃, the pressure is 1.4MPa, and the time is 4min; the temperature for the gluing and shaping stage is 135℃, the pressure is 1.2MPa, and the time is 3min. After the board blank is cut to size, negative pressure is applied to the longitudinal ducts on the first edge formed by the cut, and the first and second treatment solutions are sequentially introduced from the opposite second edge. After heat curing the longitudinal ducts, a wax-containing sealing layer is formed at the ends of the longitudinal ducts, and wooden edge banding strips are pressed on to obtain anti-mildew and moisture-proof wood-based panels for furniture.

[0089] In Example 2, reed stalks and wheat stalks were selected as natural materials. The natural materials were cut into 400mm long segments, washed, and pre-dried to achieve a moisture content of 11%. Subsequently, the natural materials were split along their length, and the pith was separated to create natural material units with a width of 16mm and a thickness of 2.8mm. Each natural material unit has a continuous outer skin side, an exposed fiber bundle side, longitudinal fiber bundles, and through longitudinal channels. A first permeable zone is formed on the continuous outer skin side, and a second permeable zone is formed on the exposed fiber bundle side. The first permeable zone includes multiple first inclined grooves, and the second permeable zone includes multiple second inclined grooves. The first and second inclined grooves are alternately arranged along the length of the natural material unit. The projection angle between the first and second inclined grooves on the same projection plane perpendicular to the thickness direction of the natural material unit is 90°. Fiber bridges extending continuously along the longitudinal fiber bundles are preserved between adjacent first and second inclined grooves.

[0090] In Example 2, the first treatment solution comprises, by mass percentage, 1.2% chitosan, 0.8% citric acid, and 98.0% water. The first treatment solution is introduced into the first sealed cavity, where a positive pressure of 0.50 MPa is applied. Simultaneously, a negative pressure of -0.085 MPa is applied into the second sealed cavity, causing the first treatment solution to enter the longitudinal channel through the second permeation zone from the exposed side of the fiber bundle and flow out from the first permeation zone. When the chitosan mass concentration in the collection pipe connected to the second sealed cavity reaches 30% of the chitosan mass concentration in the first treatment solution, the introduction of the first treatment solution is stopped, and liquid control is implemented to ensure that the amount of first treatment solution retained in the natural material unit is 17% of the oven-dry mass of the natural material unit. The second treatment solution comprises, by mass percentage, 1.0% tannic acid, 0.6% calcium lactate, and 98.4% water. After controlling the first treatment solution, the second treatment solution is introduced into the second sealed cavity. A positive pressure of 0.45 MPa is applied inside the second sealed cavity, while a negative pressure of -0.085 MPa is applied inside the first sealed cavity. This causes the second treatment solution to flow backward from the continuous outer skin side through the first permeation zone into the through longitudinal channel and out through the second permeation zone. The impregnation with the second treatment solution is complete when the tannic acid concentration in the collection pipe connected to the first sealed cavity is 38% of the tannic acid concentration in the second treatment solution, and the absolute value of the difference in tannic acid concentration between two adjacent measurements is 2 percentage points.

[0091] In Example 2, natural material units, sequentially impregnated with a first treatment solution and a second treatment solution, are sandwiched between a first and a second breathable thickness limiting plate and maintained at 63°C and 80% relative humidity for 30 minutes. Then, dry hot air at 115°C is introduced into the longitudinally penetrating channels, alternating between the first and second flow directions four times. Subsequently, the mixture is maintained at 140°C for 10 minutes, and the moisture content of the natural material units is adjusted to 8%, resulting in modified natural material units. These modified natural material units are then laid as a first and a second natural material core layer, with the longitudinal fiber bundles of the first and second natural material core layers forming a 90° angle, and the continuous outer skin sides of the two layers facing each other. Subsequently, wood veneers are glued to the outer sides of both layers, and the resulting boards are pre-pressed, segmented hot-pressed, and cooled to solidify. During the segmented hot pressing process, the temperature for the venting stage of the ducts is 95℃, the pressure is 0.7MPa, and the time is 100s; the temperature for the core layer compaction stage is 135℃, the pressure is 1.8MPa, and the time is 6min; the temperature for the bonding and shaping stage is 145℃, the pressure is 1.5MPa, and the time is 5min. After the slab is cut to length, negative pressure is applied to the longitudinal ducts at the first edge formed by the cut, and the first and second treatment solutions are sequentially introduced from the opposite second edge. During the through-fill impregnation process, the first treatment solution is introduced into each group of supplementary impregnation channels until the chitosan mass concentration in the corresponding suction compartment is 26% of the chitosan mass concentration in the first treatment solution introduced into the corresponding supply compartment; after liquid control, the second treatment solution is introduced until the tannic acid mass concentration in the corresponding suction compartment is 32% of the tannic acid mass concentration in the second treatment solution introduced into the corresponding supply compartment. After completing the impregnation, the longitudinal channels are heat-cured, and a wax-containing sealing layer and a wooden edge banding are formed at the ends of the longitudinal channels to obtain anti-mildew and moisture-proof wood boards for furniture.

[0092] In Example 3, corn stalks and reed stalks were selected as natural materials. The natural materials were cut into 600mm long segments, washed, and pre-dried to achieve a moisture content of 14%. Subsequently, the natural materials were split along their length, and the pith was separated to create natural material units with a width of 25mm and a thickness of 4.0mm. Each natural material unit has a continuous outer skin side, an exposed fiber bundle side, longitudinal fiber bundles, and through longitudinal channels. A first permeable zone is formed on the continuous outer skin side, and a second permeable zone is formed on the exposed fiber bundle side. The first permeable zone includes multiple first inclined grooves, and the second permeable zone includes multiple second inclined grooves. The first and second inclined grooves are alternately arranged along the length of the natural material unit. The projection angle between the first and second inclined grooves on the same projection plane perpendicular to the thickness direction of the natural material unit is 120°. Fiber bridges extending continuously along the longitudinal fiber bundles are preserved between adjacent first and second inclined grooves.

[0093] In Example 3, the first treatment solution comprises, by mass percentage, 1.6% chitosan, 1.2% citric acid, and 97.2% water. The first treatment solution is introduced into the first sealed cavity, where a positive pressure of 0.65 MPa is applied. Simultaneously, a negative pressure of -0.095 MPa is applied into the second sealed cavity, causing the first treatment solution to enter the longitudinal channel through the second permeation zone from the exposed side of the fiber bundle and flow out from the first permeation zone. When the chitosan mass concentration in the collection pipe connected to the second sealed cavity reaches 40% of the chitosan mass concentration in the first treatment solution, the introduction of the first treatment solution is stopped, and liquid control is implemented to ensure that the amount of first treatment solution retained in the natural material unit is 22% of the oven-dry mass of the natural material unit. The second treatment solution comprises, by mass percentage, 1.4% tannic acid, 0.9% calcium lactate, and 97.7% water. After controlling the first treatment solution, the second treatment solution is introduced into the second sealed cavity. A positive pressure of 0.60 MPa is applied inside the second sealed cavity, while a negative pressure of -0.095 MPa is applied inside the first sealed cavity. This causes the second treatment solution to flow backward from the continuous outer skin side through the first permeation zone into the through longitudinal channel and out through the second permeation zone. The impregnation with the second treatment solution is complete when the tannic acid concentration in the collection pipe connected to the first sealed cavity is 50% of the tannic acid concentration in the second treatment solution, and the absolute value of the difference in tannic acid concentration between two adjacent measurements is 0 percentage points.

[0094] In Example 3, natural material units, sequentially impregnated with a first treatment solution and a second treatment solution, are sandwiched between a first and a second breathable thickness limiting plate and maintained at 70°C and 90% relative humidity for 40 minutes. Then, dry hot air at 125°C is introduced into the longitudinally penetrating channels, alternating between the first and second flow directions five times. Subsequently, the mixture is maintained at 150°C for 15 minutes, and the moisture content of the natural material units is adjusted to 6%, resulting in modified natural material units. These modified natural material units are then laid as a first and a second natural material core layer, with the longitudinal fiber bundles of the first and second natural material core layers forming a 90° angle, and the continuous outer skin sides of the two layers facing each other. Subsequently, wood veneers are glued to the outer sides of both layers, and the resulting boards are pre-pressed, segmented hot-pressed, and cooled to solidify. During the segmented hot pressing process, the temperature for the venting stage of the ducts is 105℃, the pressure is 0.9MPa, and the time is 150s; the temperature for the core layer compaction stage is 145℃, the pressure is 2.2MPa, and the time is 8min; the temperature for the bonding and shaping stage is 155℃, the pressure is 1.8MPa, and the time is 6min. After the slab is cut to length, negative pressure is applied to the longitudinal ducts at the first edge formed by the cut, and the first and second treatment solutions are sequentially introduced from the opposite second edge. During the through-fill impregnation process, the first treatment solution is introduced into each group of supplementary impregnation channels until the chitosan mass concentration in the corresponding suction compartment is 35% of the chitosan mass concentration in the first treatment solution introduced into the corresponding supply compartment; after liquid control, the second treatment solution is introduced until the tannic acid mass concentration in the corresponding suction compartment is 45% of the tannic acid mass concentration in the second treatment solution introduced into the corresponding supply compartment. After completing the impregnation, the longitudinal channels are heat-cured, and a wax-containing sealing layer and a wooden edge banding are formed at the ends of the longitudinal channels to obtain anti-mildew and moisture-proof wood boards for furniture.

[0095] Table 1 shows the main numerical ranges for the three embodiments.

[0096] Table 1 Comparison of Parameter Items and Implementation Examples

[0097] As can be seen from Examples 1, 2 and 3, even when the types of natural materials, the size of the natural material units, the impregnation pressure, the concentration of the treatment liquid, the retention amount of the first treatment liquid, the thermosetting temperature, the core layer laying angle and the endpoint of the through-through supplementary impregnation all change, it is still possible to produce furniture-grade mildew-proof and moisture-proof wood panels with a composite modified layer, an inner interface layer and a port sealing layer.

[0098] To verify the impact of different treatment methods on the performance of the boards, Comparative Examples 1 to 4 were set up. Comparative Example 1 used a surface-mixed coating of anti-mildew and moisture-proof treatment medium without double-cavity impregnation; Comparative Example 2 formed longitudinally extending cracks without retaining fiber bridges; Comparative Example 3 directly sealed the edges after cutting to length without supplementary impregnation; Comparative Example 4 used a one-time immersion treatment after pre-mixing the first and second treatment solutions. The main process differences between Examples 1 to 3 and Comparative Examples 1 to 4 are shown in Table 2.

[0099] Table 2 Comparison of parameters between the examples and comparative examples

[0100] Examples 1 to 3 and Comparative Examples 1 to 4 were subjected to characterization tests on the retention of the treatment solution and the inner wall of the longitudinal pores. During testing, samples were taken from a region 10 mm to 50 mm inward from the end of the plate and from the middle region of the plate. Tannic acid content was detected by liquid chromatography, calcium ion content by inductively coupled plasma atomic absorption spectrometry, and the thickness of the composite modified layer was measured by microscopic cross-section. The test results are shown in Table 3.

[0101] Table 3 Comparison of Experimental Data

[0102] As shown in Table 3, in Examples 1 to 3, the mass concentration ratios of chitosan and tannic acid in the liquid collection pipeline were all within the set ranges, and a composite modified layer was formed on the inner wall of the longitudinal channel. In Comparative Example 1, no double-cavity through-hole impregnation was performed, and the treatment liquid was mainly distributed on the surface of the natural material and at local openings. In Comparative Example 4, two treatment liquids were pre-mixed and then immersed in a single treatment, and the average thickness of the composite modified layer on the inner wall of the longitudinal channel was lower than that in Examples 1 to 3.

[0103] The boards prepared in Examples 1 to 3 and Comparative Examples 1 to 4 were tested for their anti-mildew and moisture-proof properties and mechanical properties. The 24-hour water absorption thickness swelling rate was determined according to the test method for water absorption thickness swelling rate of wood-based panels in GB / T 17657; the mildew resistance level was determined according to the test method for mildew resistance of wood in GB / T 13942.1; and the static bending strength and internal bond strength were determined according to the test methods for mechanical properties of wood-based panels. The test results are shown in Table 4, and the moisture-proof performance comparison curves are shown below. Figure 6 As shown.

[0104] Table 4. Material Performance Test Results

[0105] To support Figure 6The moisture-proof performance comparison curves shown indicate that the water absorption thickness expansion rate of the samples from Example 2, Comparative Example 1, Comparative Example 3, and Comparative Example 4 after immersion in water for 2 hours, 6 hours, 12 hours, and 24 hours was measured. The test results are shown in Table 5.

[0106] Table 5. Test Results

[0107] As shown in Tables 4 and 5, the 24-hour water absorption thickness expansion rate, end moisture absorption weight gain rate, and mildew resistance of Examples 1 to 3 are all superior to those of Comparative Examples 1 and 4. The end moisture absorption weight gain rate of Example 2 is 3.6%, while that of Comparative Example 3, which did not undergo post-cutting supplementary impregnation, is 10.8%. This indicates that supplementary impregnation, thermosetting, and end sealing along the longitudinal channels after the board is cut to length can reduce end moisture absorption caused by re-exposing the channels after cutting. Although Comparative Example 2 underwent bidirectional impregnation and post-cutting supplementary impregnation, the permeation zone of Comparative Example 2 did not retain fiber bridges, and its static bending strength and internal bond strength were lower than those of Example 2. This indicates that retaining fiber bridges while forming the first and second permeation zones is beneficial for maintaining the longitudinal fiber continuity of the natural material units.

[0108] The hot pressing and drying processes were monitored, and the mass ratio of condensate in each independent flow chamber of the edge guide box and the time required to reach the target moisture content were recorded. The test results are shown in Table 6.

[0109] Table 6 Comparison of Experimental Data

[0110] As shown in Table 6, Examples 1 to 3 monitor the exhaust and condensate discharge of the channels through edge guide boxes, independent guide cavities, and partitioned hot press plates, so that the ratio of the maximum condensate mass to the minimum condensate mass in the same edge guide box is controlled within the range of 1 to 1.20. The maximum difference in surface moisture content and the warpage after hot pressing are lower than those of Comparative Examples 1, 2, and 4.

[0111] In an alternative embodiment, the natural material can be reed stalks alone, or a mixture of reed stalks and wheat straw, rice straw and wheat straw, or corn stalks and reed stalks. When the natural material is corn stalks with larger pores, the retention rate of the first treatment liquid can be controlled to 18% to 22%; when the natural material is rice stalks with smaller pores, the retention rate of the first treatment liquid can be controlled to 12% to 16%. The aforementioned parameter adjustments are all based on the premise that the first treatment liquid can enter the through-the-longitudinal pores and that the second treatment liquid can penetrate in the reverse direction and form a composite modified layer within the through-the-longitudinal pores.

[0112] In another alternative embodiment, the dual-cavity impregnation fixture can be a single-piece fixture or multiple parallel impregnation fixtures. For continuous production lines, the first sealing cavity, the second sealing cavity, the liquid supply line, the pressure regulating line, and the liquid collection line can be arranged in a roller-type continuous clamping mechanism, allowing the natural material units to pass through the first treatment liquid impregnation zone, the liquid control zone, the second treatment liquid impregnation zone, and the thickness-limited thermosetting zone with the conveyor belt. For small-batch production, a batch impregnation fixture can be used, placing multiple natural material units side by side between the first clamping plate and the second clamping plate, and sealing the first and second penetration zones separately through partitioned sealing frames.

[0113] In another alternative implementation, the edge guide box can be installed before hot pressing or after pre-pressing and before hot pressing. The number of independent guide cavities in the edge guide box can be set to 3, 4, 6, or 8 depending on the width of the slab. The zoned hot pressing plate can adopt a multi-cylinder independent pressurization structure or a structure with flexible pressure pads and multiple pressure sensors. By using the feedback relationship between the condensate quality output from the independent guide cavities and the hot pressing pressure of the corresponding plate area, zoned control of venting and hot pressing can be achieved.

[0114] In another alternative embodiment, the through-impregnation can be performed only on the two sets of opposite edges after cutting, or it can be performed after the board has been processed to form drilled, grooved, or tenoned sections. The injection holes of the wood sealant can be configured as a single central injection hole or multiple dispersed injection holes; the guide channels can be arranged radially, circumferentially, or in a stepped manner along the wood sealant to accommodate the through-longitudinal channels exposed at different processing locations. With the aforementioned configuration, the first and second treatment liquids can enter the through-longitudinal channels near the processing location, and after hot-press curing, a localized sealing structure is formed by the wax-containing sealing layer and the wood sealant.

[0115] The aforementioned implementation method focuses on processing the through-and-through longitudinal channels of natural materials. In the natural material unit preparation stage, a composite modified layer is formed through a first penetration zone, a second penetration zone, a dual-cavity impregnation fixture, a first treatment liquid, a second treatment liquid, and a thickness-limited thermosetting process. In the board forming stage, the channels are vented and glued for shaping through a first natural material core layer, a second natural material core layer, an inner interface layer, an edge guide box, and a partitioned hot press plate. In the sizing and subsequent furniture processing stages, the re-exposed through-and-through longitudinal channels are supplemented with through-and-through impregnation, thermosetting, a port sealing layer, and wooden sealing components, allowing the anti-mildew and moisture-proof treatment medium to enter the through-and-through longitudinal channels inside the natural material, and the channel sections re-exposed after cutting or processing are treated.

[0116] It should be noted that the embodiments of the present invention have better implementability and are not intended to limit the present invention in any way. Any person skilled in the art may use the above-disclosed technical content to change or modify it into equivalent effective embodiments. However, any modifications or equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A method for preparing mildew-proof and moisture-proof wood-based panels for furniture, characterized in that, include: At least one of the following natural materials—reed stalks, rice stalks, wheat stalks, and corn stalks—is longitudinally split and the pith is separated to create a natural material unit with a continuous outer skin side, an exposed fiber bundle side, longitudinal fiber bundles, and a through longitudinal channel. A first permeation zone is formed on the continuous outer skin side, and a second permeation zone is formed on the exposed fiber bundle side. The first permeation zone and the second permeation zone are respectively connected to the through longitudinal channel and are offset along the length direction. The natural material unit is loaded into a double-cavity impregnation fixture, so that the first treatment solution containing chitosan and citric acid flows from the exposed side of the fiber bundle through the second permeation zone into the through longitudinal channel and flows out from the first permeation zone. After liquid control, the second treatment solution containing tannic acid and calcium lactate flows from the continuous outer skin side through the first permeation zone into the through longitudinal channel in the opposite direction and flows out from the second permeation zone. The impregnated natural material unit is subjected to limited-thickness thermosetting to form a composite modified layer, thereby obtaining the modified natural material unit; The modified natural material units are cross-laid into a first natural material core layer and a second natural material core layer with the outer skin sides facing each other, and wood veneer is glued on the outside. The board blank is formed by pre-pressing, segmented hot pressing and cooling. After the board blank is cut to size, the first treatment liquid and the second treatment liquid are sequentially introduced into the through longitudinal channel for continuous impregnation. Then, after heat curing and port sealing, the anti-mildew and moisture-proof wood board for furniture is obtained.

2. The method for preparing anti-mildew and moisture-proof wood-based panels for furniture according to claim 1, characterized in that, The first permeation zone includes a plurality of first inclined grooves extending from the continuous outer skin side toward the through longitudinal channel, and the second permeation zone includes a plurality of second inclined grooves extending from the exposed fiber bundle side toward the through longitudinal channel; the first inclined grooves and the second inclined grooves are alternately arranged along the length direction of the natural material unit, and the angle between the projections of the first inclined grooves and the second inclined grooves on the same projection plane perpendicular to the thickness direction of the natural material unit is 60° to 120°, and fiber bridges extending continuously along the longitudinal fiber bundle are retained between adjacent first inclined grooves and second inclined grooves.

3. The method for preparing anti-mildew and moisture-proof wood-based panels for furniture according to claim 2, characterized in that, The dual-cavity impregnation fixture includes a first clamping plate, a second clamping plate, a first sealing frame, a second sealing frame, a first sealing cavity, and a second sealing cavity. The first clamping plate is attached to the exposed side of the fiber bundle, and the first sealing frame surrounds the second permeation area and together with the first clamping plate forms the first sealing cavity. The second clamping plate is attached to the continuous outer skin side, and the second sealing frame surrounds the first permeation area and together with the second clamping plate forms the second sealing cavity. The first sealing cavity and the second sealing cavity are respectively connected to the corresponding liquid supply pipeline, pressure regulating pipeline, and liquid collection pipeline. The pipelines corresponding to the first sealing cavity and the pipelines corresponding to the second sealing cavity are independent of each other.

4. The method for preparing anti-mildew and moisture-proof wood-based panels for furniture according to claim 3, characterized in that, The first treatment solution comprises, by mass percentage, 0.8%–1.6% chitosan, 0.5%–1.2% citric acid, and the balance water. The first treatment solution is introduced into the first sealed cavity, and a positive pressure of 0.35–0.65 MPa is applied within the first sealed cavity, while a negative pressure of -0.075–-0.095 MPa is applied within the second sealed cavity. When the chitosan mass concentration in the collection pipeline connected to the second sealed cavity is 20%–40% of the chitosan mass concentration in the first treatment solution, the natural material unit is controlled to ensure that the retention amount of the first treatment solution in the natural material unit is 12%–22% of the oven-dry mass of the natural material unit.

5. The method for preparing anti-mildew and moisture-proof wood-based panels for furniture according to claim 4, characterized in that, The second treatment solution comprises, by mass percentage, 0.6%–1.4% tannic acid, 0.3%–0.9% calcium lactate, and the remainder water. After controlling the first treatment solution, the second treatment solution is introduced into the second sealed cavity, and a positive pressure of 0.30–0.60 MPa is applied in the second sealed cavity, while a negative pressure of -0.075–-0.095 MPa is applied in the first sealed cavity. When the mass concentration of tannic acid in the collection pipeline connected to the first sealed cavity is 25%–50% of the mass concentration of tannic acid in the second treatment solution, and the absolute value of the difference in tannic acid mass concentration obtained from two adjacent measurements is 0–5 percentage points, the impregnation with the second treatment solution is completed.

6. The method for preparing anti-mildew and moisture-proof wood-based panels for furniture according to claim 5, characterized in that, The thickness-limited thermosetting process includes: clamping a natural material unit, which has been sequentially impregnated with the first treatment liquid and the second treatment liquid, between a first breathable thickness-limiting plate and a second breathable thickness-limiting plate, and maintaining it at 55–70°C and 70%–90% relative humidity for 20–40 minutes; introducing dry hot air at 105–125°C into the through longitudinal channel, and alternately switching between a first flow direction with the first permeation zone as the air inlet and the second permeation zone as the air outlet, and a second flow direction with the second permeation zone as the air inlet and the first permeation zone as the air outlet; subsequently maintaining it at 130–150°C for 5–15 minutes, and adjusting the moisture content of the natural material unit to 6%–10%.

7. The method for preparing anti-mildew and moisture-proof wood-based panels for furniture according to claim 6, characterized in that, According to the arrangement of the through longitudinal channels in the width direction of the natural material unit, the through longitudinal channels are divided into multiple channel groups; during the thickness-limited thermosetting process, the inlet pressure, outlet pressure, and outlet air moisture content of each channel group under the current dry hot air flow direction are detected respectively; the channel groups with an inlet pressure-outlet pressure difference of 0.02-0.08 MPa and an absolute value of the difference in outlet air moisture content between two adjacent measurements of 0-2 g / kg are switched to the heat preservation state; the first flow direction and the second flow direction are alternately switched for the channel groups in the dry hot air input state until all the channel groups are switched to the heat preservation state.

8. The method for preparing anti-mildew and moisture-proof wood-based panels for furniture according to claim 1, characterized in that, Multiple modified natural material units constituting the first natural material core layer are arranged in parallel to each other, and the two ends of each through longitudinal channel in the first natural material core layer are respectively connected to the first set of opposite edges of the slab; multiple modified natural material units constituting the second natural material core layer are arranged in parallel to each other, and the two ends of each through longitudinal channel in the second natural material core layer are respectively connected to the second set of opposite edges of the slab; the extension direction of the first set of opposite edges forms an angle of 70° to 90° with the extension direction of the second set of opposite edges, and the longitudinal fiber bundles of the first natural material core layer and the second natural material core layer form an angle of 70° to 90°; the projections of the first permeation zone in the first natural material core layer and the first permeation zone in the second natural material core layer in the thickness direction are staggered.

9. The method for preparing anti-mildew and moisture-proof wood-based panels for furniture according to claim 8, characterized in that, Multiple bonding windows and multiple hydrophobic isolation areas are respectively provided on the continuous outer skin sides of the first natural material core layer and the second natural material core layer facing each other. The bonding windows and the hydrophobic isolation areas are alternately distributed on the plate surface of each continuous outer skin side. Each hydrophobic isolation area is arranged around the corresponding first penetration area and coated with a hydrophobic treatment liquid containing n-octyltriethoxysilane and carnauba wax. The bonding windows provided on the first natural material core layer and the bonding windows provided on the second natural material core layer correspond to each other in the plate thickness direction, and the corresponding bonding windows are filled with adhesive.

10. A type of mildew-proof and moisture-proof wood-based panel for furniture, characterized in that, The mold-proof and moisture-proof wood-based panels for furniture are prepared by the method for preparing mold-proof and moisture-proof wood-based panels for furniture as described in any one of claims 1 to 9.

Images