Formaldehyde-free environment-friendly multilayer solid wood composite floor and preparation method thereof
By employing formaldehyde-free adhesive hot-pressing combined with a self-locking structure and segmented hot-pressing process in multi-layer solid wood composite flooring, the problem of excessive penetration of formaldehyde-free adhesive caused by excessive adhesive usage has been solved, achieving stable connection and low-cost production of environmentally friendly multi-layer solid wood composite flooring.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ZHEJIANG ONE-HORNED RHINO FURNITURE CO LTD
- Filing Date
- 2026-03-02
- Publication Date
- 2026-05-12
AI Technical Summary
Existing environmentally friendly multi-layer solid wood composite flooring uses a large amount of adhesive while ensuring connection strength. This leads to excessive penetration of formaldehyde-free adhesive, which may damage the fiber structure and cause delamination and bulging after long-term use.
Formaldehyde-free adhesive is used to heat-press a self-locking structure in the central area, reducing the amount of adhesive used. Mechanical self-locking connection is achieved through grid grooves and serrated structures, and the use of adhesive is optimized by combining segmented hot-pressing process.
While ensuring the strength of the floor connections, the amount of adhesive used is reduced, environmental friendliness is improved, the adhesion between each layer is enhanced, excessive extrusion of adhesive is avoided, and production costs and energy consumption are reduced.
Smart Images
Figure CN122008364A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to an environmentally friendly flooring, particularly a formaldehyde-free environmentally friendly multi-layer solid wood composite flooring and its preparation method. Background Technology
[0002] Multi-layer engineered wood flooring is made of multiple layers of solid wood veneers, which are cross-laminated and hot-pressed together. From top to bottom, it generally includes a top layer (using hardwood veneers such as oak, walnut, teak, and maple), 7-13 layers of core material (using fast-growing softwoods such as eucalyptus, birch, pine, and poplar), and a bottom layer (using stable veneers such as poplar and birch). The core principle is to achieve high stability by vertically offsetting internal stress through the wood grain of adjacent layers. The production process involves log rotary cutting, drying, assembly, hot pressing, sanding, veneering, grooving, and painting.
[0003] Existing environmentally friendly multi-layer engineered wood flooring, even if it uses formaldehyde-free adhesive, still requires a lot of adhesive between each layer to ensure the connection strength due to the large number of layers. This increases the cost of using formaldehyde-free adhesive and may also cause excessive penetration of the formaldehyde-free adhesive into the surface wood, damaging the fiber structure and leading to delamination and bulging after long-term use. Summary of the Invention
[0004] The purpose of this invention is to provide a formaldehyde-free, environmentally friendly multi-layer solid wood composite flooring and its preparation method. This invention, while ensuring the bonding strength of the flooring, reduces the amount of adhesive used, making it more environmentally friendly.
[0005] The technical solution of this invention: A formaldehyde-free environmentally friendly multi-layer solid wood composite flooring, comprising a balanced solid wood layer, a functional solid wood layer, and a wear-resistant solid wood layer arranged sequentially from bottom to top. The central area between the balanced solid wood layer, the functional solid wood layer, and the wear-resistant solid wood layer is formed by hot pressing with formaldehyde-free adhesive, and the edge portion is connected by a self-locking structure. The central area of the upper surface of the balanced solid wood layer is provided with a first grid groove, the lower surface of the functional solid wood layer is provided with a plurality of first pressing blocks corresponding to the first grid groove, the central area of the upper surface of the functional solid wood layer is provided with a second grid groove, and the lower surface of the wear-resistant solid wood layer is provided with a plurality of second pressing blocks corresponding to the second grid groove.
[0006] In the aforementioned formaldehyde-free environmentally friendly multi-layer solid wood composite flooring, a moisture-proof layer is provided below the balancing solid wood layer, and a wave-shaped shock-absorbing sheet is provided between the balancing solid wood layer and the moisture-proof layer. There is a certain buffer gap between the shock-absorbing sheet and the balancing solid wood layer and the moisture-proof layer. Shock-absorbing blocks are provided in the upper and lower recesses of the shock-absorbing sheet. Reinforcing ribs that cooperate and snap together with the corresponding shock-absorbing blocks are provided on both the balancing solid wood layer and the moisture-proof layer.
[0007] In the aforementioned formaldehyde-free environmentally friendly multi-layer solid wood composite flooring, the sides of the first grid groove are interconnected through a first channel, and the sides of the second grid groove are interconnected through a second channel.
[0008] In the aforementioned formaldehyde-free environmentally friendly multi-layer solid wood composite flooring, the self-locking structure includes a first sawtooth structure located on at least one side edge of the upper surface of the balancing solid wood layer, a second sawtooth structure located on at least one side edge of the upper surface of the functional solid wood layer, a third sawtooth structure located on the lower surface of the functional solid wood layer that meshes with the first sawtooth structure, and a fourth sawtooth structure located on the lower surface of the wear-resistant solid wood layer that meshes with the second sawtooth structure.
[0009] In the aforementioned formaldehyde-free environmentally friendly multi-layer solid wood composite flooring, a first annular groove is provided on the outside of the first grid groove on the balancing solid wood layer, and the groove opening height of the first annular groove is lower than the groove opening height of the first grid groove; a second annular groove is provided on the outside of the second grid groove on the functional solid wood layer, and the groove opening height of the second annular groove is lower than the groove opening height of the second grid groove.
[0010] In the aforementioned formaldehyde-free environmentally friendly multi-layer solid wood composite flooring, the first sawtooth structure is connected to the first annular groove, and the depth of the first sawtooth structure is less than the depth of the first annular groove; the second sawtooth structure is connected to the second annular groove, and the depth of the second sawtooth structure is less than the depth of the first annular groove.
[0011] In the aforementioned formaldehyde-free environmentally friendly multi-layer solid wood composite flooring, the upper surfaces of the first and second annular grooves are provided with annular uniformly distributed meshes.
[0012] In the aforementioned formaldehyde-free environmentally friendly multi-layer solid wood composite flooring, the functional solid wood layer has a honeycomb hollow structure inside, and the honeycomb hollow structure is filled with air, flame retardant materials, sound-absorbing materials, or antibacterial materials.
[0013] The above-mentioned method for preparing formaldehyde-free environmentally friendly multi-layer solid wood composite flooring includes the following steps:
[0014] S1. Fine micro-scratches are processed on the upper surface of the balance solid wood layer, the upper and lower surfaces of the functional solid wood layer, and the lower surface of the wear-resistant solid wood layer;
[0015] S2. A first grid groove, a first annular groove, and a first serrated structure are respectively machined from the center outward on the upper surface of the balancing solid wood layer. A reinforcing rib is machined on the lower surface of the balancing solid wood layer. A second grid groove, a second annular groove, and a second serrated structure are respectively machined from the center outward on the upper surface of the functional solid wood layer. A first pressing block is machined in the central area of the lower surface of the functional solid wood layer. A third serrated structure is machined on the edge of the lower surface of the functional solid wood layer. A second pressing block is machined in the central area of the lower surface of the wear-resistant solid wood layer. A fourth serrated structure is machined on the edge of the lower surface of the wear-resistant solid wood layer.
[0016] S3. Immerse the balanced solid wood layer, functional solid wood layer and wear-resistant solid wood layer separately in an antibacterial solution, treat them with ultrasound, and then take them out and dry them, controlling the moisture content of the balanced solid wood layer, functional solid wood layer and wear-resistant solid wood layer to be 6%-7%;
[0017] S4. Arrange a uniformly distributed mesh on the first and second annular grooves, apply formaldehyde-free glue to the central area of the upper surface of the balance solid wood layer and the functional solid wood layer, and leave a certain amount of formaldehyde-free glue at the bottom of the first and second mesh grooves, while leaving the edge parts uncoated.
[0018] S5. The balanced solid wood layer, the functional solid wood layer and the wear-resistant solid wood layer are superimposed on each other, wherein the first pressing block is embedded in the first grid groove, the third sawtooth structure meshes with the first sawtooth structure, the second pressing block is embedded in the second grid groove, the fourth sawtooth structure meshes with the second sawtooth structure, and then hot pressing is performed.
[0019] S6. After hot pressing, shock-absorbing pads and a moisture-proof layer are installed in sequence below the balancing solid wood layer to obtain formaldehyde-free environmentally friendly multi-layer solid wood composite flooring.
[0020] In the aforementioned preparation method, in step S5, the initial hot pressing temperature is 50~60℃ and the pressure is 0.3~0.5MPa; the middle hot pressing temperature is 120~160℃ and the pressure is 1~2MPa; and the later hot pressing temperature is 90~120℃ and the pressure is 0.5~0.8MPa to avoid excessive extrusion of the adhesive.
[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0022] This invention optimizes the flooring structure by using formaldehyde-free adhesive for hot-pressing between the balancing solid wood layer, functional solid wood layer, and wear-resistant solid wood layer in the central area. The edges of these layers utilize a self-locking structure to create mechanical self-locking force, replacing some of the adhesive's bonding strength and reducing the amount of adhesive required. The embedding structure between the first pressing block and the first grid groove, and the embedding structure between the second pressing block and the second grid groove, achieves a stable connection. The height of the first pressing block is less than the depth of the first grid groove, and the height of the second pressing block is less than the depth of the second grid groove. A small amount of formaldehyde-free adhesive can be stored in both the first and second grid grooves. When the first pressing block is embedded in the first grid groove, the bottom of the first pressing block contacts the formaldehyde-free adhesive in the first grid groove, and the bottom of the second pressing block contacts the formaldehyde-free adhesive in the second grid groove, forming adhesive nails. This enhances the adhesion between the solid wood layers while reducing the use of formaldehyde-free adhesive, making it more environmentally friendly.
[0023] The hot-pressing process was adjusted to employ segmented pressurization, improving hot-pressing uniformity, reducing adhesive consumption, enhancing adhesive layer bonding efficiency, and preventing excessive adhesive extrusion. Segmented temperature control was also adopted to avoid insufficient wetting due to premature adhesive curing, thus reducing subsequent temperature and energy consumption. Attached Figure Description
[0024] Figure 1 This is a schematic diagram of the structure of the present invention.
[0025] Figure 2 This is a structural diagram of the functional solid wood layer.
[0026] Figure 3 This is a schematic diagram of the connection structure between the functional solid wood layer and the wear-resistant solid wood layer.
[0027] Figure 4 This is a schematic diagram of the connection structure between the solid wood layer and the moisture-proof layer.
[0028] Figure 5 This is a schematic diagram of a wedge-shaped first serration structure.
[0029] Figure 6 This is a schematic diagram of the first serrated structure of another wedge shape.
[0030] The markings in the attached diagram are as follows: 1. Balanced solid wood layer; 11. First grid groove; 111. First channel; 12. First sawtooth structure; 13. First annular groove; 14. Reinforcing rib; 2. Functional solid wood layer; 21. First pressing block; 22. Second grid groove; 221. Second channel; 23. Second sawtooth structure; 24. Third sawtooth structure; 25. Second annular groove; 26. Uniformly distributed mesh; 27. Honeycomb hollow structure; 3. Wear-resistant solid wood layer; 31. Second pressing block; 32. Fourth sawtooth structure; 4. Moisture-proof layer; 5. Shock-absorbing sheet; 51. Shock-absorbing block. Detailed Implementation
[0031] The present invention will be further described below with reference to the accompanying drawings and embodiments, but this should not be construed as limiting the present invention.
[0032] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, a hinged connection, a rotatable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.
[0033] Example:
[0034] like Figures 1-4As shown, a formaldehyde-free environmentally friendly multi-layer solid wood composite floor includes a balancing solid wood layer 1, a functional solid wood layer 2, and a wear-resistant solid wood layer 3 arranged sequentially from bottom to top. The central areas between the balancing solid wood layer 1 and the functional solid wood layer 2, and between the functional solid wood layer 2 and the wear-resistant solid wood layer 3, are formed by hot pressing with formaldehyde-free adhesive. The edge portions between the balancing solid wood layer 1 and the functional solid wood layer 2, and between the functional solid wood layer 2 and the wear-resistant solid wood layer 3, are connected by a self-locking structure. The upper surface of the balancing solid wood layer 1 has a first grid groove 11 in the central area. The lower surface of the functional solid wood layer 2 has several first pressing blocks 21 corresponding to the first grid groove 11, the height of which is less than the depth of the first grid groove 11. The upper surface of the functional solid wood layer 2 has a second grid groove 22 in the central area. The lower surface of the wear-resistant solid wood layer 3 has several second pressing blocks 31 corresponding to the second grid groove 22, the height of which is less than the depth of the second grid groove 22.
[0035] The balanced solid wood layer 1, functional solid wood layer 2, and wear-resistant solid wood layer 3 are hot-pressed together in the central area using formaldehyde-free adhesive. The edges of these layers utilize a self-locking structure to create mechanical self-locking force, replacing some of the adhesive's bonding strength and reducing the amount of adhesive required. The embedding structure between the first pressing block 21 and the first grid groove 11, and the embedding structure between the second pressing block 31 and the second grid groove 22, achieves a stable connection. The height of the first pressing block 21 is less than the depth of the first grid groove 11, and the height of the second pressing block 31 is less than the depth of the second grid groove 22. A small amount of formaldehyde-free adhesive can be stored in the first grid groove 11 and the second grid groove 22. When the first pressing block 21 is embedded in the first grid groove 11, the bottom of the first pressing block 21 contacts the formaldehyde-free adhesive in the first grid groove 11, and the bottom of the second pressing block 31 contacts the formaldehyde-free adhesive in the second grid groove 22, forming adhesive nails. This enhances the adhesion between the solid wood layers while reducing the amount of formaldehyde-free adhesive used.
[0036] The formaldehyde-free adhesive uses existing plant protein adhesives, API adhesives, MDI adhesives, etc. The balancing solid wood layer 1 is made of environmentally friendly high-density fiberboard prepared with formaldehyde-free adhesives; the functional solid wood layer 2 is made of pine, poplar, eucalyptus, etc.; the wear-resistant solid wood layer 3 is made of oak, beech, birch, oak, etc.
[0037] A moisture-proof layer 4 is provided below the balanced solid wood layer 1. A corrugated shock-absorbing sheet 5 is provided between the balanced solid wood layer 1 and the moisture-proof layer 4, with a certain buffer gap between the shock-absorbing sheet 5 and the balanced solid wood layer 1 and the moisture-proof layer 4. Shock-absorbing blocks 51 are provided in the upper and lower recesses of the shock-absorbing sheet 5. Reinforcing ribs 14 are provided on both the balanced solid wood layer 1 and the moisture-proof layer 4 to engage with the corresponding shock-absorbing blocks 51. The corrugated shock-absorbing sheet 5 between the balanced solid wood layer 1 and the moisture-proof layer 4, and the connection between the shock-absorbing sheet 5 and the balanced solid wood layer 1 and the moisture-proof layer 4 via the reinforcing ribs 14 and the shock-absorbing blocks 51, not only achieves formaldehyde-free operation but also provides deformation energy absorption through the shock-absorbing sheet 5, and improves the strength, rigidity, and compressive strength of the balanced solid wood layer 1 and the moisture-proof layer 4 through the reinforcing ribs 14. An edge banding is also provided around the balanced solid wood layer 1 and the moisture-proof layer 4.
[0038] The bottom of the first grid groove 11 is interconnected through the first channel 111, and the bottom of the second grid groove 22 is interconnected through the second channel 221, so that the formaldehyde-free glue stored in the first grid groove 11 and the second grid groove 22 can be distributed more evenly throughout the grid groove, thereby achieving a uniform connection between the solid wood layer 1, the functional solid wood layer 2 and the wear-resistant solid wood layer 3.
[0039] The self-locking structure includes a first serrated structure 12 located at least one edge of the upper surface of the balancing solid wood layer 1, a second serrated structure 23 located at least one edge of the upper surface of the functional solid wood layer 2, a third serrated structure 24 located on the lower surface of the functional solid wood layer 2 that meshes with the first serrated structure 12, and a fourth serrated structure 32 located on the lower surface of the wear-resistant solid wood layer 3 that meshes with the second serrated structure 23. The edges of the balancing solid wood layer 1 and the functional solid wood layer 2 are engaged by the third serrated structure 24 and the first serrated structure 12, and the edges of the functional solid wood layer 2 and the wear-resistant solid wood layer 3 are engaged by the fourth serrated structure 32 and the second serrated structure 23, forming a mechanical self-locking force to prevent disengagement.
[0040] To improve the connection strength between different floor layers, a self-locking serrated structure can be installed along all four edges. The serrated structure can be symmetrical or wedge-shaped, for example... Figure 5 and Figure 6 The serrated structure shown ensures that the layers of solid wood do not shift laterally or vertically, improving the stability of the composite flooring, avoiding stress concentration, and enhancing its fatigue and impact resistance.
[0041] The balanced solid wood layer 1 has a first annular groove 13 outside the first grid groove 11, and the opening height of the first annular groove 13 is lower than the opening height of the first grid groove 11. The functional solid wood layer 2 has a second annular groove 25 outside the second grid groove 22, and the opening height of the second annular groove 25 is lower than the opening height of the second grid groove 22. The first annular groove 13 and the second annular groove 25 are designed to receive formaldehyde-free glue overflowing during hot pressing, preventing formaldehyde-free glue from overflowing to the outside and causing waste and pollution. The opening of the first annular groove 13 and the opening of the first grid groove 11 form a slope design with an angle of less than 3°, forming a guide surface, which makes it easier for excess formaldehyde-free glue overflowing during central hot pressing to flow into the annular groove.
[0042] The first serrated structure 12 is connected to the first annular groove 13, and the depth of the first serrated structure 12 is less than the depth of the first annular groove 13; the second serrated structure is connected to the second annular groove 25, and the depth of the second serrated structure is less than the depth of the first annular groove 13. Designing the first serrated structure 12 to be connected to the first annular groove 13 and the second serrated structure to be connected to the second annular groove 25 allows any excess formaldehyde-free adhesive flowing into either the first annular groove 13 or the second annular groove 25 to flow into the first serrated structure 12 or the second serrated structure 23. This further enhances the adhesive bonding at the edges of each solid wood layer under a mechanically self-locking state, improving the connection and stability between the layers.
[0043] The upper surfaces of both the first annular groove 13 and the second annular groove 25 are provided with annular uniformly distributed mesh 26. During hot pressing, excess formaldehyde-free adhesive entering the annular groove first passes through the uniformly distributed mesh 26, causing the mesh 26 to be coated with formaldehyde-free adhesive. During hot pressing, the mesh 26 bonds to the upper solid wood layer through the formaldehyde-free adhesive, strengthening the connection strength at the annular groove edges of the flooring. The uniformly distributed mesh 26 uses carbon fiber mesh or metal mesh fabric to form a reinforcing skeleton, improving the strength of the composite flooring, reducing internal stress, lowering the risk of cracking, and, in the case of underfloor heating, quickly conducting heat and improving heat utilization.
[0044] The functional solid wood layer 2 has a honeycomb-like hollow structure 27 inside, which is filled with air, flame-retardant material, sound-absorbing material, or antibacterial material. The honeycomb-like hollow structure 27, filled with air, flame-retardant material, sound-absorbing material, or antibacterial material, gives the functional solid wood layer 2 excellent properties such as elasticity, mildew and antibacterial properties, sound insulation, heat insulation, or flame retardancy. The thickness of the functional solid wood layer 2 is greater than the thickness of the balancing solid wood layer 1, and the thickness of the balancing solid wood layer 1 is greater than the thickness of the wear-resistant solid wood layer 3.
[0045] As can be seen from the above, the present invention uses adhesive sprayed in the central area of the balanced solid wood layer 1, the functional solid wood layer 2 and the wear-resistant solid wood layer 3, and the edges do not need to be glued due to the self-locking structure, thereby reducing the amount of formaldehyde-free glue used and making it more environmentally friendly.
[0046] The above-mentioned method for preparing formaldehyde-free environmentally friendly multi-layer solid wood composite flooring includes the following steps:
[0047] S1. Fine micro-scratches are processed on the upper surface of the balanced solid wood layer 1, the upper and lower surfaces of the functional solid wood layer 2, and the lower surface of the wear-resistant solid wood layer 3. The depth of the micro-scratches is 0.05-0.1mm, and the spacing between adjacent micro-scratches is 0.5-1mm. The micro-scratches can guide the adhesive to form a mesh film and enhance the mechanical interlocking force between the layers.
[0048] S2. A first grid groove 11, a first annular groove 13, and a first serrated structure 12 are respectively machined from the center outward on the upper surface of the balancing solid wood layer 1. A reinforcing rib 14 is machined on the lower surface of the balancing solid wood layer 1. A second grid groove 22, a second annular groove 25, and a second serrated structure 23 are respectively machined from the center outward on the upper surface of the functional solid wood layer 2. A first pressing block 21 is machined in the central area of the lower surface of the functional solid wood layer 2. A third serrated structure 24 is machined on the edge of the lower surface of the functional solid wood layer 2. A second pressing block 31 is machined in the central area of the lower surface of the wear-resistant solid wood layer 3. A fourth serrated structure 32 is machined on the edge of the lower surface of the wear-resistant solid wood layer 3.
[0049] S3. Immerse the balanced solid wood layer 1, functional solid wood layer 2, and wear-resistant solid wood layer 3 separately in an antibacterial solution, perform ultrasonic treatment, and then remove and dry them. Control the moisture content of the balanced solid wood layer 1, functional solid wood layer 2, and wear-resistant solid wood layer 3 to 6%-7%. If the moisture content is too low, the wood fibers will absorb the adhesive; if it is too high, water vapor will be generated during hot pressing, damaging the adhesive layer. Precise moisture control can reduce the ineffective loss of adhesive and avoid floor deformation and warping due to differences in moisture content.
[0050] S4. Arrange a uniformly distributed mesh 26 on the first annular groove 13 and the second annular groove 25, apply formaldehyde-free glue to the central area of the upper surface of the balance solid wood layer 1 and the functional solid wood layer 2, and leave a certain amount of formaldehyde-free glue at the bottom of the first mesh groove 11 and the second mesh groove 22, and do not apply glue to the edge parts.
[0051] S5. The balanced solid wood layer 1, functional solid wood layer 2, and wear-resistant solid wood layer 3 are stacked on top of each other. The first pressing block 21 is embedded in the first grid groove 11, and the third sawtooth structure 24 engages with the first sawtooth structure 12. The second pressing block 31 is embedded in the second grid groove 22, and the fourth sawtooth structure 32 engages with the second sawtooth structure 23. Then, hot pressing is performed. In the initial stage of hot pressing, the temperature is 50-60℃ and the pressure is 0.3-0.5MPa to expel air between the veneers. In the middle stage of hot pressing, the temperature is 120-160℃ and the pressure is 1-2MPa to promote adhesive impregnation. In the later stage of hot pressing, the temperature is 90-120℃ and the pressure is 0.5-0.8MPa. Segmented pressurization improves the uniformity of hot pressing, reduces adhesive consumption, enhances the bonding efficiency of the adhesive layers, and avoids excessive adhesive extrusion. Segmented temperature control avoids insufficient impregnation caused by premature adhesive curing, reducing temperature and energy consumption in the later stages.
[0052] S6. After hot pressing, install the shock-absorbing sheet 5 and the moisture-proof layer 4 in sequence below the balance solid wood layer 1.
[0053] This invention reduces the amount of formaldehyde-free adhesive used while ensuring the stability and connection strength of multi-layer solid wood flooring, and enhances the compressive strength, deformation resistance, and shock absorption performance of multi-layer solid wood flooring.
[0054] The parts of this invention not described in detail are prior art and therefore will not be specifically described here.
Claims
1. A formaldehyde-free, environmentally friendly multi-layer solid wood composite flooring, characterized in that: It includes a balanced solid wood layer (1), a functional solid wood layer (2) and a wear-resistant solid wood layer (3) arranged sequentially from bottom to top. The central area between the balanced solid wood layer (1), the functional solid wood layer (2) and the wear-resistant solid wood layer (3) is formed by hot pressing with formaldehyde-free glue, and the edge part is connected by a self-locking structure. The upper surface of the balanced solid wood layer (1) is provided with a first grid groove (11) in the central area. The lower surface of the functional solid wood layer (2) is provided with a number of first pressing blocks (21) corresponding to the first grid groove (11). The upper surface of the functional solid wood layer (2) is provided with a second grid groove (22). The lower surface of the wear-resistant solid wood layer (3) is provided with a number of second pressing blocks (31) corresponding to the second grid groove (22).
2. The formaldehyde-free environmentally friendly multi-layer solid wood composite flooring according to claim 1, characterized in that: A moisture-proof layer (4) is provided below the balancing solid wood layer (1). A wave-shaped shock-absorbing sheet (5) is provided between the balancing solid wood layer (1) and the moisture-proof layer (4). There is a certain buffer gap between the shock-absorbing sheet (5) and the balancing solid wood layer (1) and the moisture-proof layer (4). The upper and lower recesses of the shock-absorbing sheet (5) are provided with shock-absorbing blocks (51). The balancing solid wood layer (1) and the moisture-proof layer (4) are provided with reinforcing ribs (14) that cooperate and snap together with the corresponding shock-absorbing blocks (51).
3. The formaldehyde-free environmentally friendly multi-layer solid wood composite flooring according to claim 1, characterized in that: The sides of the first grid groove (11) are interconnected through the first channel (111), and the sides of the second grid groove (22) are interconnected through the second channel (221).
4. The formaldehyde-free environmentally friendly multi-layer solid wood composite flooring according to claim 1, characterized in that: The self-locking structure includes a first sawtooth structure (12) located on at least one side edge of the upper surface of the balancing solid wood layer (1), a second sawtooth structure (23) located on at least one side edge of the upper surface of the functional solid wood layer (2), a third sawtooth structure (24) located on the lower surface of the functional solid wood layer (2) that meshes with the first sawtooth structure (12), and a fourth sawtooth structure (32) located on the lower surface of the wear-resistant solid wood layer (3) that meshes with the second sawtooth structure.
5. The formaldehyde-free environmentally friendly multi-layer solid wood composite flooring according to claim 4, characterized in that: The balanced solid wood layer (1) has a first annular groove (13) outside the first grid groove (11), and the groove opening height of the first annular groove (13) is lower than the groove opening height of the first grid groove (11); the functional solid wood layer (2) has a second annular groove (25) outside the second grid groove (22), and the groove opening height of the second annular groove (25) is lower than the groove opening height of the second grid groove (22).
6. The formaldehyde-free environmentally friendly multi-layer solid wood composite flooring according to claim 5, characterized in that: The first sawtooth structure (12) is connected to the first annular groove (13), and the depth of the first sawtooth structure (12) is less than the depth of the first annular groove (13); the second sawtooth structure is connected to the second annular groove (25), and the depth of the second sawtooth structure is less than the depth of the first annular groove (13).
7. The formaldehyde-free environmentally friendly multi-layer solid wood composite flooring according to claim 4, characterized in that: The upper surfaces of the first annular groove (13) and the second annular groove (25) are provided with annular uniformly distributed mesh (26).
8. The formaldehyde-free environmentally friendly multi-layer solid wood composite flooring according to claim 1, characterized in that: The functional solid wood layer (2) has a honeycomb hollow structure (27) inside, and the honeycomb hollow structure (27) is filled with air, flame retardant material, sound-absorbing material or antibacterial material.
9. The method for preparing formaldehyde-free environmentally friendly multi-layer solid wood composite flooring according to any one of claims 1-8, characterized in that: Includes the following steps: S1. Fine micro-scratches are processed on the upper surface of the balance solid wood layer (1), the upper and lower surfaces of the functional solid wood layer (2), and the lower surface of the wear-resistant solid wood layer (3). S2. A first grid groove (11), a first annular groove (13), and a first sawtooth structure (12) are respectively processed from the center outward on the upper surface of the balancing solid wood layer (1). A reinforcing rib (14) is processed on the lower surface of the balancing solid wood layer (1). A second grid groove (22), a second annular groove (25), and a second sawtooth structure (23) are respectively processed from the center outward on the upper surface of the functional solid wood layer (2). A first pressing block (21) is processed in the central area of the lower surface of the functional solid wood layer (2). A third sawtooth structure (24) is processed on the edge of the lower surface of the functional solid wood layer (2). A second pressing block (31) is processed in the central area of the lower surface of the wear-resistant solid wood layer (3). A fourth sawtooth structure (32) is processed on the edge of the lower surface of the wear-resistant solid wood layer (3). S3. Immerse the balanced solid wood layer (1), the functional solid wood layer (2), and the wear-resistant solid wood layer (3) in an antibacterial solution, ultrasonically treat them, and then take them out and dry them. Control the moisture content of the balanced solid wood layer (1), the functional solid wood layer (2), and the wear-resistant solid wood layer (3) to be 6%-7%. S4. Arrange a uniform mesh (26) on the first annular groove (13) and the second annular groove (25), apply formaldehyde-free glue to the central area of the upper surface of the balance solid wood layer (1) and the functional solid wood layer (2), and leave a certain amount of formaldehyde-free glue at the bottom of the first mesh groove (11) and the second mesh groove (22), and do not apply glue to the edge part. S5. The balanced solid wood layer (1), the functional solid wood layer (2) and the wear-resistant solid wood layer (3) are stacked on top of each other, wherein the first pressing block (21) is embedded in the first grid groove (11), the third sawtooth structure (24) meshes with the first sawtooth structure (12), the second pressing block (31) is embedded in the second grid groove (22), the fourth sawtooth structure (32) meshes with the second sawtooth structure (23), and then hot pressing is performed; S6. After hot pressing, damping pads (5) and moisture-proof layer (4) are installed in sequence below the balanced solid wood layer (1) to obtain formaldehyde-free environmentally friendly multi-layer solid wood composite flooring.
10. The preparation method according to claim 9, characterized in that: In step S5, during the initial stage of hot pressing, the hot pressing temperature is 50~60℃ and the pressure is 0.3~0.5MPa; during the middle stage of hot pressing, the hot pressing temperature is 120~160℃ and the pressure is 1~2MPa; during the later stage of hot pressing, the hot pressing temperature is 90~120℃ and the pressure is 0.5~0.8MPa.