Bamboo board for furniture products

Abstract

The present application relates to the technical field of bamboo board processing, and particularly relates to a bamboo board for furniture products, which comprises multiple portions of first bamboo and second bamboo; the first bamboo and the second bamboo are dried to the same first moisture content; the multiple portions of the dried first bamboo and the second bamboo are impregnated with glue and spliced to obtain multiple first boards and second boards; the first boards and the second boards are cut into first board materials and second board materials which are spliced into blanks in a staggered manner; the surfaces of the first board materials and the second board materials which are connected to each other are mating surfaces, and the mating surfaces are rough surfaces; the moisture content of the blanks is increased to a second moisture content; the present application reuses unqualified bamboo and splices part of the boards for reuse; the moisture content is increased, and the mating surfaces are rough surfaces, so that the rough surfaces are more tightly engaged due to different expansion coefficients, mechanical locking is formed, glue is used for bonding, and pores are further filled on the basis of the mechanical locking, so that chemical bonding and mechanical engagement are formed in a dual action.

Description

Technical Field

[0001] This invention relates to the field of bamboo board processing technology, and specifically to a bamboo board for use in furniture products. Background Technology

[0002] To ensure stable performance, existing bamboo materials used in furniture production often involve discarding a large number of bamboo strips with uneven density, using only high-quality bamboo strips with similar density. This results in a raw material utilization rate of less than 60%, with most of the remaining bamboo materials of varying densities being discarded or used as low-end consumables at low prices. This leads to a serious waste of bamboo resources and persistently high production costs.

[0003] Because bamboo naturally varies in density depending on its growing region and growth cycle, high-density bamboo strips are darker in color, harder, and heavier. If multiple high-density bamboo strips are spliced ​​together, the resulting bamboo board will be extremely heavy, with poor toughness and elasticity, making it prone to cracking. Conversely, lower-density bamboo strips are lighter in color, have better toughness but insufficient load-bearing capacity. If multiple low-density bamboo strips are spliced ​​together, the resulting bamboo board will lack support and is prone to breakage. Therefore, splicing bamboo strips of different densities can improve utilization. However, due to the different water absorption and expansion characteristics of bamboo strips of different densities, shear stress concentration occurs in the adhesive layers connecting them during use, leading to cracking and delamination at the joints.

[0004] Therefore, the present invention provides a bamboo board for furniture products that can avoid cracking and delamination caused by splicing bamboo boards of different densities. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a bamboo board for furniture products that can avoid cracking and delamination caused by splicing bamboo boards of different densities.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A bamboo board for furniture products includes multiple portions of first bamboo and second bamboo, wherein the density of the first bamboo is greater than that of the second bamboo. Dry the first and second bamboo materials to the same initial moisture content; Multiple portions of dried first bamboo are glued together to obtain multiple first boards; multiple portions of dried second bamboo are glued together to obtain multiple second boards; the first and second boards are cut into first planks and second planks, which are of equal length, width and thickness. Multiple first and second plates are interlocked to form a blank, with the outermost sides of the blank being first plates; the surfaces where the first and second plates connect are mating surfaces, which are rough surfaces; the mating surfaces are bonded together with adhesive. The blank is clamped by applying external force from both sides, and the moisture content of the blank is increased to a second moisture content, which is greater than the first moisture content. The upper and lower surfaces of the blank are flattened under the second moisture content environment, and the blank is cut to a predetermined length. After cutting, glue is applied to the outer surface of the blank to form a sealing glue layer that fully covers the blank. After the glue layer stabilizes, it is hot-pressed to obtain bamboo board.

[0007] Preferably, the density ratio of the first bamboo material to the second bamboo material is 1.3 to 1.7:1.

[0008] Preferably, the first moisture content is 6%-9%, the second moisture content is 12%-18%, and the difference between the second moisture content and the first moisture content is greater than or equal to 5%.

[0009] Preferably, the mating surface is a rough surface formed by steel brushing or sandblasting, with a roughness Ra of 80-200μm, and random pits with a depth of 150-400μm and a diameter of 0.3-1.0mm are distributed on the mating surface.

[0010] Preferably, the external force clamping on both sides is 0.6-1.8 MPa, and the direction is perpendicular to the mating surface; in the clamping state, the billet is kept in the second moisture content environment for 2-6 hours, and the leveling process is carried out after the moisture content is uniform and stable.

[0011] Preferably, during the glue impregnation process, the first or second bamboo material is first evacuated in a vacuum chamber with a vacuum degree of 0.08-0.095MPa for 15-30 minutes, and then pressurized to 0.8-1.5MPa and maintained for 60-120 minutes.

[0012] Preferably, the hot pressing is a multi-stage hot pressing; the multi-stage hot pressing includes a first stage with a temperature of 120°C, a pressure of 1.0 MPa, and a holding time of 8 min; a second stage with a temperature of 140°C, a pressure of 1.5 MPa, and a holding time of 12 min; and a third stage with a temperature of 110°C, a pressure of 0.8 MPa, and a holding time of 6 min.

[0013] Preferably, after hot pressing, the boards are removed and cured at room temperature for 7 days to obtain the final bamboo board.

[0014] Preferably, the sealant layer has multiple layers.

[0015] The beneficial effects of this invention are as follows: Firstly, the blank is formed by interlacing the first and second boards, eliminating the need for complex assembly processes and requiring only a simple interlacing technique. This results in more uniform performance of the finished product. It also reduces costs while allowing for the reuse of substandard bamboo materials and the ability to cut and reassemble portions of substandard boards. The reassembled bamboo boards possess sufficient support and elasticity to meet the requirements of home furnishing products. Furthermore, the outermost sides of the blank are both made of the first board, which is harder and less prone to damage; therefore, placing it on the outermost side reduces the possibility of damage to the blank.

[0016] Secondly, by performing the first glue penetration and splicing at the first moisture content, the moisture content of the raw material can be increased to a second moisture content. Combined with the rough surface of the mating surfaces, the increased moisture content allows for stress release before final leveling, sealing, and cutting of the bamboo boards. Because the first and second boards have different densities, their expansion coefficients also differ. Therefore, the increased moisture content releases stress, resulting in a tighter interlocking between the rough surfaces due to their different expansion coefficients, reducing gaps between the mating surfaces and creating a mechanically locked connection. Furthermore, the mating surfaces are bonded with glue, further filling the pores on top of the mechanical locking, forming a continuous adhesive film. During the gluing process, a dual effect of chemical bonding and mechanical interlocking is achieved, reducing the likelihood of cracking due to interface stress concentration when the moisture content changes later. Combined with increasing the moisture content during clamping, the gap width is reduced, effectively increasing the contact area between the mating surfaces, further enhancing the mechanical locking effect during subsequent expansion. This results in a more stable connection, overcoming the cracking problem at the connection point in existing technologies.

[0017] Third, the sealing adhesive layer is formed after cutting and grinding, which can isolate moisture and prevent external moisture changes from affecting the stability of the mechanical locking of the mating surfaces after connection. Since the blank is in the second moisture content state at this time, the moisture content gradient between the adhesive layer and the blank is zero, and the adhesive can penetrate and cure more evenly. It will not cause the adhesive layer to be too thin or incompletely cured due to the substrate absorbing water too quickly. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of a bamboo board used in furniture products according to a specific embodiment of the present invention; Figure 2 This is a physical image of a bamboo board used in furniture products, according to a specific embodiment of the present invention. Labeling explanation: 1. First plate material; 2. Second plate material. Detailed Implementation

[0019] To explain in detail the technical content, objectives, and effects of the present invention, the following description is provided in conjunction with the embodiments and accompanying drawings.

[0020] Please refer to Figures 1 to 2 A bamboo board for furniture products, comprising multiple portions of first bamboo and second bamboo, wherein the density of the first bamboo is greater than that of the second bamboo; Dry the first and second bamboo materials to the same initial moisture content; Multiple portions of dried first bamboo are glued together to obtain multiple first boards; multiple portions of dried second bamboo are glued together to obtain multiple second boards; the first and second boards are cut into first board 1 and second board 2, wherein the first board and the second board are of equal length, width and thickness. Multiple first plates 1 and second plates 2 are interlocked to form a blank, and the outermost sides of both sides of the blank are first plates 1; the surfaces where the first plates 1 and second plates 2 connect are mating surfaces, and the mating surfaces are rough surfaces; the mating surfaces are bonded together with glue; The blank is clamped by applying external force from both sides, and the moisture content of the blank is increased to a second moisture content, which is greater than the first moisture content. The upper and lower surfaces of the blank are flattened under the second moisture content environment, and the blank is cut to a predetermined length. After cutting, glue is applied to the outer surface of the blank to form a sealing glue layer that fully covers the blank. After the glue layer stabilizes, it is hot-pressed to obtain bamboo board.

[0021] As described above, firstly, by interlacing the first and second boards to form the blank, a simple interlacing process is required, eliminating the need for complex assembly. This results in more uniform performance of the finished product. Furthermore, it reduces costs while enabling the reuse of substandard bamboo materials and allowing for the cutting and reassembly of portions of substandard boards. The reassembled bamboo boards possess sufficient support and elasticity to meet the requirements of home furnishing products. Moreover, the outermost sides of the blank are both made of the first board, which is harder and less prone to damage; therefore, placing it on the outermost side reduces the possibility of blank damage.

[0022] Secondly, by performing the first glue penetration and splicing at the first moisture content, the moisture content of the raw material can be increased to a second moisture content. Combined with the rough surface of the mating surfaces, the increased moisture content allows for stress release before final leveling, sealing, and cutting of the bamboo boards. Because the first and second boards have different densities, their expansion coefficients also differ. Therefore, the increased moisture content releases stress, resulting in a tighter interlocking between the rough surfaces due to their different expansion coefficients, reducing gaps between the mating surfaces and creating a mechanically locked connection. Furthermore, the mating surfaces are bonded with glue, further filling the pores on top of the mechanical locking, forming a continuous adhesive film. During the gluing process, a dual effect of chemical bonding and mechanical interlocking is achieved, reducing the likelihood of cracking due to interface stress concentration when the moisture content changes later. Combined with increasing the moisture content during clamping, the gap width is reduced, effectively increasing the contact area between the mating surfaces, further enhancing the mechanical locking effect during subsequent expansion. This results in a more stable connection, overcoming the cracking problem at the connection point in existing technologies.

[0023] Third, the sealing adhesive layer is formed after cutting and grinding, which can isolate moisture and prevent external moisture changes from affecting the stability of the mechanical locking of the mating surfaces after connection. Since the blank is in the second moisture content state at this time, the moisture content gradient between the adhesive layer and the blank is zero, and the adhesive can penetrate and cure more evenly. It will not cause the adhesive layer to be too thin or incompletely cured due to the substrate absorbing water too quickly.

[0024] Furthermore, the density ratio of the first bamboo material to the second bamboo material is 1.3 to 1.7:1.

[0025] As can be seen from the above description, when the density ratio of the first bamboo material to the second bamboo material is less than 1.3, the expansion difference is insufficient and the self-compression effect is weak; when it is higher than 1.7, the interfacial shear stress is mismatched, and internal cracks are prone to occur after hot pressing. A ratio of 1.3 to 1.7:1 makes the interfacial shear stress generated by the expansion difference lower than the cross-grain shear strength of the bamboo material.

[0026] Furthermore, the first moisture content is 6%-9%, the second moisture content is 12%-18%, and the difference between the second moisture content and the first moisture content is greater than or equal to 5%.

[0027] As described above, the first moisture content of 6% to 9% is below the fiber saturation point, with no excess free water in the cell lumen. During glue infiltration, the glue can fully occupy the pores without being diluted, resulting in optimal bonding strength and water resistance. The second moisture content of 12% to 18% is close to the fiber saturation point, with the fiber in a semi-plasticized state, fully releasing growth stress and drying shrinkage stress. The 5% difference in moisture content ensures sufficient expansion difference, thereby guaranteeing sufficient stress for digital mechanical condensation.

[0028] Furthermore, the mating surface is a rough surface formed by steel brushing or sandblasting, with a roughness Ra of 80-200μm, and random pits with a depth of 150-400μm and a diameter of 0.3-1.0mm are distributed on the mating surface.

[0029] As described above, the rough surface and random pits increase the adhesive area and mechanical interlocking points. During the second moisture content swelling and clamping process, the mating surfaces of the first and second plates undergo micro-regional plastic deformation. The adhesive is squeezed into the pits and solidifies to form "adhesive nails," making the interface rely not only on chemical bonding but also on mechanical anchoring. This mechanical anchoring, in conjunction with the internal moisture swelling prestress, significantly enhances the peel strength and fatigue resistance.

[0030] Furthermore, the external force clamping both sides is 0.6-1.8 MPa, and the direction is perpendicular to the mating surface; in the clamping state, the billet is kept in the second moisture content environment for 2-6 hours, and the leveling process is carried out after the moisture content is uniform and stable.

[0031] As can be seen from the above description, continuous clamping pressure causes the first and second plates to creep and plastically adapt at the interface during the wet expansion process, eliminating the initial splicing gaps and making the adhesive layer thickness uniform. After maintaining the moisture content until it is uniform and stable, processing is carried out to avoid processing springback and thickness deviation caused by moisture gradient, which significantly improves the flatness and dimensional stability of the plates and reduces warping deformation in subsequent use.

[0032] Furthermore, during the glue impregnation process, the first or second bamboo material is first evacuated in a vacuum chamber with a vacuum degree of 0.08-0.095MPa for 15-30 minutes, and then pressurized to 0.8-1.5MPa and maintained for 60-120 minutes.

[0033] As described above, the low moisture content of the first moisture content means that there is almost no liquid water occupying the cell cavities and pits. The degassing resistance is small and more thorough during the vacuum stage, allowing the adhesive to penetrate deep into the pits and cell cavities under pressure, forming a continuous adhesive-bamboo interpenetrating structure. The subsequent increase to the second moisture content allows these deeply distributed but not fully cured adhesives to diffuse further with the participation of moisture, which is equivalent to a secondary diffusion of the adhesive penetration, improving the penetration effect.

[0034] Furthermore, the hot pressing is a multi-stage hot pressing; the multi-stage hot pressing includes a first stage with a temperature of 120°C, a pressure of 1.0 MPa, and a holding time of 8 min; a second stage with a temperature of 140°C, a pressure of 1.5 MPa, and a holding time of 12 min; and a third stage with a temperature of 110°C, a pressure of 0.8 MPa, and a holding time of 6 min.

[0035] As described above, the multi-stage hot-pressing process achieves a dynamic balance between stress release and adhesive curing within the bamboo board through stepwise changes in temperature and pressure. The first stage involves rapid shaping at medium temperature and high pressure; the second stage promotes full cross-linking and curing of the adhesive, ensuring bond strength; and the third stage, involving cooling and pressure reduction, effectively alleviates residual stress within the board, preventing warping or cracking caused by excessive temperature differences. This progressive heat treatment strategy not only improves the dimensional stability of the bamboo board but also significantly enhances its surface smoothness and mechanical properties, thus meeting the manufacturing requirements of high-quality furniture products.

[0036] Furthermore, after hot pressing, the boards are removed and cured at room temperature for 7 days to obtain the final bamboo board.

[0037] As can be seen from the above description, the room temperature curing stage allows the residual stress inside the bamboo board to be further released, and the adhesive to complete its final curing.

[0038] Furthermore, the sealant layer has multiple layers.

[0039] As can be seen from the above description, using multiple layers of sealant can reduce the change in moisture content of bamboo boards due to the failure of some sealant layers.

[0040] Example 1 The specific preparation process of a bamboo board for furniture products is as follows: Raw material selection: The first type of bamboo is the root section of 4-year-old moso bamboo with an air-dry density of 0.78 g / cm³; the second type of bamboo is the tip section of the same batch of moso bamboo with an air-dry density of 0.52 g / cm³; the density ratio is 1.5:1.

[0041] Step 1: Place the two types of bamboo into a drying kiln separately and dry them to a moisture content of 8% (first moisture content). After removing them from the kiln, allow them to equilibrate for 48 hours.

[0042] Step Two: The dried first and second bamboo materials are then impregnated with adhesive. The impregnation process is as follows: vacuum at 0.09 MPa for 20 minutes, then pressurize to 1.2 MPa and maintain the pressure for 90 minutes. A phenolic resin adhesive with a solid content of 45% is used. After impregnation, the bamboo materials are spliced ​​together to form the first and second boards, and cured at room temperature for 24 hours.

[0043] Step 3: Cut the first and second boards into first and second board materials with dimensions of 1800-2200mm (length) × 50-100mm (width) × 20-35mm (thickness). The two types of boards should be of equal length, width, and thickness.

[0044] Step 4: Use a steel brush to roughen the mating surfaces of the first and second plates, controlling the roughness Ra to 120μm, forming random pits with a depth of about 200~300μm and a diameter of about 0.5~0.8mm on the mating surfaces.

[0045] Step 5: Apply phenolic resin adhesive (180g / m²) to the mating surfaces, and arrange the first and second plates alternately to form the blank, with the outermost sides of both blanks being the first plate. In this embodiment, the blank assembly structure is: first plate - second plate - first plate - second plate - first plate, a total of 5 layers.

[0046] Step Six: Place the assembled billet into the clamping device and apply a clamping force of 1.2 MPa from both sides in the width direction, perpendicular to the mating surface. Simultaneously, place the billet in a conditioned environment with a temperature of 25°C and a relative humidity of 85% to raise the billet's moisture content to 15% (second moisture content), with a moisture content difference of 7%. Maintain this clamping state for 4 hours until the moisture content is uniform and stable.

[0047] Step 7: In the above-mentioned humidified environment, the upper and lower surfaces of the billet are planed flat, and the billet is cut to a predetermined length.

[0048] Step 8: Immediately after cutting, evenly apply sealant (using polyurethane sealant, 120g / m²) to all six outer surfaces of the blank to form a fully covered sealant layer. After the sealant layer is surface dry (approximately 30 minutes), perform multi-stage hot pressing: Stage 1: Temperature 120℃, Pressure 1.0MPa, held for 8 minutes; Stage 2: Temperature 140℃, Pressure 1.5MPa, held for 12 minutes; Stage 3: Temperature 110℃, Pressure 0.8MPa, held for 6 minutes. After hot pressing, remove the board and cure at room temperature for 7 days to obtain the final bamboo board.

[0049] Example 2 A bamboo board for furniture products, the specific preparation process of which is the same as that in Example 1 will not be repeated here, the difference being: Raw material selection: The first type of bamboo has an air-dry density of 0.75 g / cm³, and the second type of bamboo has an air-dry density of 0.56 g / cm³, with a density ratio of 1.34:1.

[0050] The first moisture content is 6%, the second moisture content is 12%, and the difference in moisture content is 6%.

[0051] Infiltration process: Vacuum at 0.08MPa for 30 minutes, then pressurize to 0.8MPa and hold for 120 minutes.

[0052] The mating surfaces are sandblasted to a roughness Ra of 80 μm, with pit depths of 150~250 μm and diameters of 0.3~0.6 mm.

[0053] The clamping force is 0.6 MPa, and it is maintained for 6 hours in an environment with a second moisture content.

[0054] The sealant layer consists of two layers: the first layer is an epoxy resin primer (80g / m²), and the second layer is a polyurethane topcoat (100g / m²).

[0055] The billet assembly structure consists of 7 layers: first plate - second plate - first plate - second plate - first plate - second plate - first plate - second plate - first plate.

[0056] The remaining process steps are the same as in Example 1.

[0057] Example 3 A bamboo board for furniture products, the specific preparation process of which is the same as that in Example 1 will not be repeated here, the difference being: Raw material selection: The first type of bamboo has an air-dry density of 0.82 g / cm³, and the second type of bamboo has an air-dry density of 0.50 g / cm³, with a density ratio of 1.64:1.

[0058] The first moisture content is 9%, the second moisture content is 18%, and the difference in moisture content is 9%.

[0059] Infiltration process: Vacuum at 0.095MPa for 15 minutes, then pressurize to 1.5MPa and hold for 60 minutes.

[0060] The mating surfaces are treated with a steel brush, with a roughness Ra of 200μm, and pit depths of 300~400μm and diameters of 0.8~1.0mm.

[0061] The clamping force is 1.8 MPa, and it is maintained for 2 hours in an environment with a second moisture content.

[0062] The hot pressing process uses four stages: the first stage is 110℃ / 0.8MPa / 5min, the second stage is 130℃ / 1.2MPa / 8min, the third stage is 150℃ / 1.6MPa / 10min, and the fourth stage is 105℃ / 0.6MPa / 5min.

[0063] The remaining process steps are the same as in Example 1.

[0064] Comparative Example 1 (Existing Conventional Process) The conventional bamboo laminated timber process in this field is adopted: bamboo density is not differentiated, and the materials are uniformly mixed and spliced; the mating surfaces are only planed (Ra approximately 10μm); after all processing is completed at a moisture content of 8%, the materials are directly hot-pressed without moisture content increase or clamping treatment; a layer of clear varnish is applied to the surface after hot pressing. The remaining raw material specifications, board dimensions, and adhesive types are the same as in Example 1.

[0065] Comparative Example 2 (without moisture content increase step) The process is basically the same as in Example 1, except that the moisture content increase in step six is ​​not performed. After assembly, the billets are directly clamped, leveled, cut, glued, and hot-pressed at the first moisture content (8%). The remaining process parameters are the same as in Example 1.

[0066] Comparative Example 3 (Mating surfaces were not roughened). The process is basically the same as in Example 1, except that the mating surfaces are only planed and not roughened with a steel brush, resulting in a roughness Ra of approximately 10 μm and no random pits. All other process parameters are the same as in Example 1.

[0067] Test data and effect verification The bamboo boards prepared in Examples 1-3 and Comparative Examples 1-3 underwent systematic performance testing. Test items included: static bending strength (MOR), modulus of elasticity (MOE), interfacial shear strength, 24-hour thickness swelling rate after water absorption, interfacial cracking rate after boiling-drying cycles, and warpage after temperature and humidity cycling tests. Five parallel samples were prepared for each test, and the average value was taken. Test methods followed the relevant provisions of GB / T 17657-2013 "Test Methods for Physical and Chemical Properties of Wood-based Panels and Decorative Wood-based Panels" and GB / T 30364-2013 "Bamboo Laminated Timber".

[0068] Table 1 Comparison of basic mechanical properties between the examples and comparative examples.

[0069] As shown in Table 1, the static bending strength of Examples 1-3 was increased by 23%-34%, the elastic modulus by 22%-37%, the interfacial shear strength by 71%-96%, and the 24-hour water absorption thickness expansion rate was reduced by 57%-71% compared to Comparative Example 1 (conventional process). The properties of Comparative Example 2 (no moisture content increase) and Comparative Example 3 (no roughening of the mating surface) were significantly lower than those of Example 1, indicating that the moisture content increase step and the roughening treatment of the mating surface played a crucial role in improving the interfacial performance.

[0070] Table 2. Experimental data for density ratio parameter optimization (other parameters are the same as in Example 1)

[0071] The data in Table 2 validates the rationality of selecting a density ratio of 1.3 to 1.7:1. When the density ratio is below 1.3 (A1, A2), the expansion difference between the two types of bamboo is insufficient, the interfacial shear strength is low, and the cracking rate after boiling-drying cycles is high. When the density ratio is above 1.7 (A8, A9), the interfacial shear stress is mismatched, obvious internal cracks appear after hot pressing, and the cracking rate after cycles also increases rapidly. Within the range of 1.3 to 1.7:1 (A3 to A7), the interfacial shear strength remains at a relatively high level of 8.7 to 10.0 MPa, the internal cracking rate after hot pressing is controlled below 3.5%, and the cyclic cracking rate is below 5.6%, resulting in the best overall performance.

[0072] Table 3. Experimental data on moisture content parameter optimization (other parameters are the same as in Example 1)

[0073] Table 3 data validates the parameter range of 6%–9% for the first moisture content, 12%–18% for the second moisture content, and a difference ≥5%. Group B6 had a moisture content difference of only 3%, insufficient expansion difference, an interfacial shear strength of only 7.0 MPa, and a warpage of 2.1 mm / m. Group B1 had a first moisture content of 5% (below 6%), where excessive glue penetration during glue infiltration led to glue layer embrittlement and decreased performance. Group B8 had a first moisture content of 10% (above 9%), with free water existing in the cell cavities, affecting the glue infiltration effect. Group B9 had a second moisture content of 20% (above 18%), excessive moisture expansion made it difficult for moisture to drain during subsequent hot pressing, easily causing blistering. Groups B2–B5 were within the optimized parameter range, with interfacial shear strengths all above 8.8 MPa and warpage controlled below 1.1 mm / m.

[0074] Table 4. Experimental data on the optimization of surface roughness parameters (other parameters are the same as in Example 1).

[0075] Table 4 data validates the parameter ranges for mating surface roughness Ra (80–200 μm), pit depth (150–400 μm), and diameter (0.3–1.0 mm). Group C1 (untreated, planed) exhibits an interfacial shear strength of only 6.1 MPa and a peel strength of 2.8 N / mm. Group C2 has insufficient roughness, resulting in fewer mechanical interlocking points and limited performance improvement. Groups C6 and C7 have excessive roughness, reducing the actual contact area of ​​the mating surfaces, preventing the adhesive from fully filling the deep pits, thus creating defects and degrading performance. Groups C3–C5, within the preferred range, achieve an interfacial shear strength of 8.9–9.8 MPa and a peel strength of 4.8–5.6 N / mm, representing improvements of 46%–61% and 71%–100% respectively compared to Group C1.

[0076] Table 5. Experimental data on the optimization of clamping process parameters (other parameters are the same as in Example 1).

[0077] The data in Table 5 validated the parameter range of clamping force (0.6–1.8 MPa) and holding time (2–6 h). Group D1 had insufficient clamping force, resulting in inadequate gap elimination and uneven adhesive layer. Group D7 had excessive clamping force (2.2 MPa), causing excessive extrusion of the adhesive layer, localized adhesive deficiency, and a decrease in interfacial shear strength. Groups D2–D6 were within the optimal range, achieving interfacial shear strength of 8.3–9.8 MPa, with thickness deviation controlled below 0.22 mm, and good adhesive layer uniformity.

[0078] Table 6. Experimental data on the optimization of adhesive diffusion process parameters (other parameters are the same as in Example 1).

[0079] Table 6 data validated the parameter range of 0.08–0.095 MPa vacuum, 15–30 min vacuuming, 0.8–1.5 MPa pressurization, and 60–120 min holding time. Group E1 had insufficient vacuum (0.06 MPa), resulting in incomplete gas removal from the cell cavities and a glue penetration depth of only 1.2 mm. Group E7's parameters exceeded the optimal range; although the penetration depth and weight gain were slightly improved, the excessively long penetration time led to decreased production efficiency, and excessive glue penetration increased the brittleness of the board. Groups E2–E6 were within the optimal range, achieving a glue penetration depth of 2.1–4.0 mm and a glue penetration weight gain of 12.3%–21.3%, balancing glue penetration effect and production efficiency.

[0080] Table 7 Results of Temperature and Humidity Cyclic Durability Test (Cyclic conditions: 20℃ / 30%RH) (40℃ / 90%RH, 24 hours per cycle, 10 cycles in total)

[0081] The temperature and humidity cycling test results in Table 7 show that after 10 cycles of severe temperature and humidity cycling, the moisture content change of Examples 1-3 was only 0.5-0.7 percentage points, the warpage was controlled below 0.8 mm / m, there were no visible cracks at the interface, and the sealant layer remained intact. In contrast, Comparative Example 1 (conventional process) showed a moisture content change of 3.8 percentage points, a warpage of 3.2 mm / m, three interface cracks, and localized detachment of the sealant layer. Comparative Examples 2 and 3 also showed varying degrees of microcracks and sealant layer defects. This fully demonstrates that this solution, through the synergistic effect of moisture content control, mechanical interlocking of mating surfaces, and the sealant layer, significantly improves the durability and dimensional stability of the boards under varying temperature and humidity conditions.

[0082] Table 8 Comparison test data between multi-stage hot pressing and single-stage hot pressing

[0083] Table 8 data verifies the effectiveness of multi-stage hot pressing. A single hot pressing resulted in a bubbling rate of 12.5%, because the rapid vaporization of moisture inside the board under high temperature and pressure prevented timely discharge. Two-stage hot pressing reduced the bubbling rate to 4.2%. Three-stage and four-stage hot pressing completely eliminated the bubbling problem, while also improving static bending strength and surface smoothness. Multi-stage hot pressing, through its process logic of first preheating at low temperature to allow slow moisture migration, then curing under high temperature and pressure, and finally setting at low temperature, effectively avoids bubbling defects.

[0084] The above description is merely a preferred embodiment of this solution and is not intended to limit the solution. For those skilled in the art, this solution can have various modifications and variations, including but not limited to: (1) Selection of bamboo species: The first and second bamboo species can be different species. For example, the first bamboo species can be high-density species such as moso bamboo and giant dragon bamboo, and the second bamboo species can be low-density species such as Cizhu bamboo and green skin bamboo; or different parts (root and tip) or different ages of the same bamboo species. As long as the density ratio is within the range of 1.3 to 1.7:1, it is acceptable.

[0085] (2) Selection of adhesives: For adhesives used for penetration and bonding of mating surfaces, commonly used adhesives in this field can be phenolic resin adhesives, melamine-formaldehyde resin adhesives, polyurethane adhesives, epoxy resin adhesives, etc. For sealant layers, polyurethane sealant, acrylic sealant, silicone sealant, etc. can be selected.

[0086] (3) Changes in the assembly structure: The number of staggers between the first and second plates can be adjusted according to the width requirements of the plates, such as 3 layers, 5 layers, 7 layers, 9 layers, etc., but the outermost two sides must be the first plates. In addition to side-to-side staggers, other staggered arrangements such as layer-by-layer butt joints can also be used to achieve the staggered arrangement of the plates.

[0087] (4) Surface treatment methods: In addition to steel brush and sandblasting, laser etching, high-pressure water jet, chemical corrosion and other methods can also be used to form rough surfaces and random pits, as long as the specified roughness and pit size are achieved.

[0088] (5) Methods to increase moisture content: In addition to humidity control in a humidity control room, spray humidification, steam treatment, water immersion and other methods can also be used to increase the moisture content of the billet. As long as the moisture content can be increased evenly to the second moisture content and kept stable.

[0089] (6) Hot pressing process: The number of stages, temperature, pressure and time of multi-stage hot pressing can be adjusted according to the thickness of the board, the type of adhesive and the production rhythm. The core principle is to first preheat and dehumidify at low temperature, then cure at high temperature, and finally shape at low temperature.

[0090] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent modifications made based on the content of the present invention specification and drawings, or direct or indirect applications in related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A bamboo board for furniture products, characterized in that, It includes multiple portions of first bamboo and second bamboo, wherein the density of the first bamboo is greater than that of the second bamboo; Dry the first and second bamboo materials to the same initial moisture content; Multiple portions of dried first bamboo are glued together to obtain multiple first boards; multiple portions of dried second bamboo are glued together to obtain multiple second boards; the first and second boards are cut into first planks and second planks, which are of equal length, width and thickness. Multiple first and second plates are interlocked to form a blank, with the outermost sides of the blank being first plates; the surfaces where the first and second plates connect are mating surfaces, which are rough surfaces; the mating surfaces are bonded together with adhesive. The blank is clamped by applying external force from both sides, and the moisture content of the blank is increased to a second moisture content, which is greater than the first moisture content. The upper and lower surfaces of the blank are flattened under the second moisture content environment, and the blank is cut to a predetermined length. After cutting, glue is applied to the outer surface of the blank to form a sealing glue layer that fully covers the blank. After the glue layer stabilizes, it is hot-pressed to obtain bamboo board.

2. The bamboo board for furniture products according to claim 1, characterized in that, The density ratio of the first bamboo material to the second bamboo material is 1.3 to 1.7:

1.

3. The bamboo board for furniture products according to claim 1, characterized in that, The first moisture content is 6%-9%, the second moisture content is 12%-18%, and the difference between the second moisture content and the first moisture content is greater than or equal to 5%.

4. The bamboo board for furniture products according to claim 1, characterized in that, The mating surface is a rough surface formed by steel brushing or sandblasting, with a roughness Ra of 80-200μm, and random pits with a depth of 150-400μm and a diameter of 0.3-1.0mm are distributed on the mating surface.

5. The bamboo board for furniture products according to claim 1, characterized in that, The external force clamping both sides is 0.6-1.8MPa, and the direction is perpendicular to the mating surface. In the clamping state, the billet is kept in the second moisture content environment for 2-6 hours, and the leveling process is carried out after the moisture content is uniform and stable.

6. The bamboo board for furniture products according to claim 1, characterized in that, During the glue infiltration process, first evacuate the first or second bamboo material in a vacuum chamber with a vacuum degree of 0.08-0.095MPa for 15-30 minutes, and then pressurize it to 0.8-1.5MPa and maintain it for 60-120 minutes.

7. The bamboo board for furniture products according to claim 1, characterized in that, The hot pressing is a multi-stage hot pressing; the multi-stage hot pressing includes the first stage temperature of 120℃, pressure of 1.0MPa, and holding for 8min; the second stage temperature of 140℃, pressure of 1.5MPa, and holding for 12min; and the third stage temperature of 110℃, pressure of 0.8MPa, and holding for 6min.

8. The bamboo board for furniture products according to claim 7, characterized in that, After hot pressing, the boards are removed and cured at room temperature for 7 days to obtain the final bamboo board.

9. The bamboo board for furniture products according to claim 1, characterized in that, The sealant layer has multiple layers.

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