Bamboo-wood composite material and preparation method thereof

Abstract

The invention discloses a bamboo-wood composite material and a preparation method thereof, and belongs to the technical field of wood-bamboo production and preparation. The preparation method comprises the steps that metal electrode plates are attached to the two opposite faces of a wood-bamboo plate, and a high-voltage electric field is applied to the wood-bamboo plate attached with the metal electrode plates for surface treatment; the pretreated wood-bamboo board is glued and assembled, and a board blank is obtained; metal electrode plates are attached to the two opposite faces of the plate blank, the plate blank attached with the metal electrode plates is put into a pressurizing device to be subjected to pressurizing treatment, a high-voltage electric field is applied to the plate blank in the pressurizing treatment process, and the bamboo-wood composite material is obtained after pressurizing treatment is completed. According to the bamboo-wood composite material and the preparation method thereof provided by the invention, the durability of the bamboo-wood composite material is more stable, and the bamboo-wood composite material has better antibacterial and anticorrosive properties.

Description

Technical Field

[0001] The invention relates to the technical field of wood and bamboo material production and preparation, and in particular to a bamboo-wood composite material and a preparation method thereof. Background Art

[0002] Wood and bamboo are recognized as renewable and sustainable biomaterials in the world today. They have special mechanical properties. Their specific gravity and density have higher specific strength than concrete and steel, and they are light in weight. Strength and stiffness increase with increasing specific gravity, especially under the condition of expansion and contraction parallel to the fiber direction. According to research, wood and bamboo are anisotropic materials that show excellent mechanical strength in three directions: transverse, chordal and radial, but each direction changes accordingly. Scientific and rational industrialization of wood and bamboo can effectively improve their economic value. At present, the application of wood and bamboo composites tends to be structural engineering. This change has aroused great interest in my country's wood and bamboo processing enterprises, construction industry, furniture and other companies. At present, researchers at home and abroad have conducted a lot of research, focusing on solving the problems in the gluing process of wood and bamboo. During the preparation process, it is difficult for adhesives to penetrate into the material and can only spread through the cell gap. Based on the above influence, the adhesive cannot be fully and evenly distributed and penetrated on the surface of wood and bamboo, which reduces the chemical crosslinking between the adhesive and the wood and bamboo, and reduces the mechanical coupling effect of the adhesive. At the same time, long-term use of engineered wood and bamboo materials is prone to problems such as low bonding strength, high impregnation peeling rate, and short product life cycle. The main reason is the poor interface performance between wood and bamboo and adhesives. The formation of the bonding interface is a complex process, which is mainly connected by the penetration and adhesion of adhesives on the surface of wood and bamboo.

[0003] The weather resistance of bamboo-wood composite materials mainly depends on many factors. If the bonding properties are less affected by environmental changes, the better the weather resistance. Therefore, the methods for improving the weather resistance and mechanical properties of bamboo-wood composite materials in this field mainly include modification of the surface of bamboo materials, modification of adhesives and optimization of process parameters.

[0004] Surface modification of wood and bamboo materials: In order to improve the bonding properties of wood and bamboo materials, people have conducted a lot of research on the surface characteristics of bamboo materials, mainly including ultrasound, alkali treatment, oxygen plasma and other methods. At present, the modification of the surface of wood and bamboo materials mostly belongs to the category of chemical pretreatment. By improving the activity of the surface of wood and bamboo materials and the compatibility of their interfaces, the bonding strength of wood and bamboo composites can be increased. Although chemical treatment of the surface of wood and bamboo materials can improve the compatibility between the substrate and the adhesive, when preparing wood and bamboo composite materials, the current bonding interface bonding bonds are disordered and discontinuous, and the ineffective bonding depth increases. In addition, the morphology of the surface of chemically treated wood and bamboo materials is often destroyed and affects the original morphology of the wood and bamboo materials. Therefore, it is not ideal to use chemical means to treat the surface of wood and bamboo materials in order to improve the comprehensive performance of wood and bamboo composite materials.

[0005] Research on adhesives: During the gluing process, a uniform adhesive is applied to the surface of the material by hot pressing. At the same time, the resin adheres or deposits on the cracks and thin-walled cell cavities formed by hot pressing, as well as on the cell walls of the basic tissues near the extension of the cracks. The impregnation ability of the adhesive is achieved by coordinating and adjusting the solid content of the adhesive, the impregnation method, the impregnation time, the impregnation time and the water content of the device. At present, most modified adhesives or high-performance adhesives such as isocyanates are used to improve the comprehensive performance of wood-bamboo composite materials. However, modified adhesives often increase production costs, increase formaldehyde emissions, and have an impact on the environment. At the same time, high-performance adhesives such as isocyanates produce harmful substances during curing, affecting health and other problems. Therefore, further in-depth research on adhesives is needed.

[0006] Application of new processes and new equipment: The molding process of wood-bamboo composite materials mainly consists of hot pressing and cold pressing (thermosetting). Both methods require high pressure during the molding process, and the impact on material properties is related to temperature, time, pressure, decompression process, density and molding type. These factors affect the rheological behavior of the resin during the bonding process, and then determine the properties of the bonding interface, which is mainly reflected in the performance differences of the products. Most of the current technologies use methods such as increasing temperature and increasing pressure. The above methods can increase the production rate to a certain extent, but excessive temperature and pressure will cause a series of problems such as excessive product compression rate and cracking of the glue layer. Therefore, it is still necessary to find new processes and new equipment to apply them to the processing of wood-bamboo composite materials.

[0007] The aforementioned Chinese invention patent with publication number CN 112405734 A, published on February 26, 2021, discloses a plywood production process and equipment thereof, the method adopts the following plywood production process, including the following steps: S1. Plasma surface treatment of wooden boards to obtain pretreated wooden boards; S2. Apply glue on the surface of pretreated wooden boards, bond adjacent pretreated wooden boards to obtain pre-bonded wooden boards; S3. Cold press the pre-bonded wooden boards at a pressure of 1.1-1.7 MPa, and let stand for 2-4 hours after cold pressing to obtain plywood; Preparation method of glue: Stir anhydrous magnesium chloride with water, add lightly burned magnesium oxide, stir and form a first premixed liquid, then add polyurethane modified styrene acrylic emulsion dropwise to the first premixed liquid, stir to obtain a second premixed liquid after the dropwise addition is completed, and finally add TIPA to the second premixed liquid, continue stirring to obtain glue. This application has the advantage of improving the water resistance of plywood. However, the disadvantage is that the wood surface treatment using plasma is time-sensitive and cannot effectively improve the surface properties of wood during the plywood preparation process, which has certain limitations.

[0008] The Chinese invention patent with the publication number CN 114347193 A, published on April 15, 2022, discloses a plywood and its production process. The invention mainly includes the following steps: S1: take a plurality of veneers and dry them, then apply adhesive on the surface of the dried veneers, and bond the plurality of veneers by the adhesive to form a pre-treated board; the adhesive includes a protein dissolution liquid, a natural protein complex and a cross-linking agent, and the cross-linking agent used is composed of glyoxal, isocyanate and thiourea in a mass ratio of (3-5): (2-4): (2-3); the natural protein complex used is composed of soybean powder and feather powder in a mass ratio of (2-3): (1-2); S2: hot-press and cut the pre-treated board in step S1 to obtain. The invention has the advantage of improving the bonding strength of the prepared plywood. However, the disadvantages are that the adhesive preparation process is complicated and costly, which is not conducive to large-scale industrial production. It also contains isocyanate, which produces harmful substances during curing and affects health.

[0009] The aforementioned Chinese invention patent with publication number CN 109015954 A, published on December 18, 2018, discloses a method for improving the weather resistance and mechanical properties of bamboo plywood, the method comprising the steps of: assembling bamboo pieces coated with adhesive and hot pressing, applying a high-voltage electric field during hot pressing, and the direction of the electric field is the same as the pressurization direction of hot pressing. It also includes the following steps: drying the bamboo pieces; coating the treated bamboo pieces with adhesive; assembling the bamboo pieces; hot pressing and applying a high-voltage electric field, after reaching the hot pressing time, turning off the high-voltage electric field, unloading the pressure, cooling, and processing and forming for standby use. The present invention can solve the problem of poor weather resistance, poor gluing properties and mechanical properties of bamboo plywood, and has the advantages of low cost and high production efficiency. However, the disadvantage is that it only increases the mechanical properties of the composite material, fails to pay attention to the mildew and rot properties of wood and bamboo materials, and limits its feasibility of industrialization. Summary of the invention

[0010] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a bamboo-wood composite material and a preparation method thereof, wherein the bamboo-wood composite material and the preparation method thereof can make the durability of the bamboo-wood composite material more stable and have better antibacterial and antiseptic properties.

[0011] To achieve the above object, the present invention is implemented by adopting the following technical solutions:

[0012] In one aspect, the present invention provides a method for preparing a bamboo-wood composite material, comprising:

[0013] Metal electrode plates are attached to two opposite sides of the wood and bamboo board, and a high voltage electric field is applied to the wood and bamboo board attached with the metal electrode plates to perform surface treatment;

[0014] Applying glue to the pretreated wood and bamboo boards to form blanks to obtain blanks;

[0015] Laminating metal electrode plates on two opposite sides of the slab, placing the slab with the metal electrode plates in a pressurizing device for pressurizing, applying a high voltage electric field to the slab during the pressurizing process, and obtaining a bamboo-wood composite material after the pressurizing process is completed;

[0016] Furthermore, before laminating the metal electrode plates on the two opposite sides of the wood-bamboo board, the wood-bamboo board is pre-treated, specifically including:

[0017] The wood and bamboo board is sanded, wherein the sanding amount of the sanding treatment is 0.5-1 mm;

[0018] The wood and bamboo boards are humidified to make the moisture content of the wood and bamboo materials 5-20%;

[0019] Balancing treatment of wood and bamboo boards.

[0020] Furthermore, metal electrode plates are bonded to two opposite sides of the wood and bamboo board, wherein the thickness of the metal electrode plates is not less than 0.5 mm, the purity is not less than 90%, and the board surface pressure of the wood and bamboo board is 0.1 MPa~0.5 MPa.

[0021] Furthermore, the material used for the metal electrode plate is selected from one of copper, silver or titanium.

[0022] Furthermore, the surface treatment of the wood and bamboo board bonded to the metal plate by applying a high-voltage electric field comprises connecting the metal electrode plates on both sides of the wood and bamboo board to the positive and negative electrodes of a high-voltage electric field generator respectively, turning on the high-voltage electric field generator to apply a high-voltage electric field to perform surface treatment on the wood and bamboo board bonded to the metal plate, wherein the voltage difference between the positive and negative electrodes is not less than 10 kV, and the surface treatment time is not less than 6 hours.

[0023] Furthermore, in the process of applying a high voltage electric field to the wood and bamboo board bonded to the metal plate for surface treatment, the electrodes connected to the metal electrode plates on both sides are interchanged, and the surface treatment is continued after changing the direction of application of the electric field.

[0024] Furthermore, the pretreated wood and bamboo boards are glued and assembled to obtain a slab, including using an adhesive to assemble multiple wooden boards into a slab, wherein the adhesive used is selected from one or more of urea-formaldehyde resin, phenol-formaldehyde resin, resorcinol-phenol-formaldehyde resin and polyurethane.

[0025] Furthermore, the slab bonded with the metal electrode plate is placed in a pressurizing device for pressurizing treatment, and a high-voltage electric field is applied to the slab during the pressurizing treatment, including connecting the metal electrode plates on both sides of the slab to the positive and negative poles of the high-voltage electric field generator respectively, turning on the high-voltage electric field generator to apply a high-voltage electric field to perform surface treatment on the slab bonded with the metal plate, wherein the direction of the applied high-voltage electric field is collinear with the direction of pressurization, the voltage difference between the positive and negative poles of the high-voltage electric field generator is not less than 1 kV, and the treatment time is not less than 200 s.

[0026] Furthermore, the pressurizing temperature of the pressurizing treatment is 30°C to 150°C, and the unit pressure on the surface of the slab is not less than 1 MPa.

[0027] In another aspect, a bamboo-wood composite material is prepared by the preparation method of the bamboo-wood composite material provided by the present invention.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The preparation method of the bamboo-wood composite material provided by the present invention forms nano-scale metal particles on the surface of the bamboo material by pre-treating the bamboo material with a high-voltage electric field, and then applies a high-voltage electric field during the pressing process, so that the nano-metal particles participate in the curing process of the adhesive. The bonding strength of the bamboo-wood composite material after the treatment fully meets the requirements, and the mechanical properties of the bamboo-wood composite material prepared by the common bonding method are greatly improved. The method is not limited by timeliness, and the durability of the bamboo-wood composite material after the treatment is more stable, and the antibacterial and anticorrosive properties are better.

[0030] The preparation method of the bamboo-wood composite material provided by the present invention utilizes electric field pretreatment followed by high-voltage electric field induced gluing to prepare a high-strength, high-durability and antibacterial and antiseptic bamboo-wood composite material, which has excellent effect and can effectively increase the added value of bamboo-wood materials, and is expected to be applied to related fields of high-performance wood-bamboo composite materials in the future. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic diagram of a high-voltage electric field surface treatment provided by an embodiment of the present invention and a comparative example;

[0032] Figure 2 A schematic diagram of the preparation of the bamboo composite material provided in the embodiments and comparative examples of the present invention;

[0033] Figure 3 The viscosity curve of the adhesive of the bamboo composite material provided by the embodiment and the comparative example of the present invention;

[0034] Figure 4 Storage modulus-frequency and loss modulus-frequency curves of bamboo composite materials provided in the embodiments and comparative examples of the present invention;

[0035] Figure 5 A microscopic photograph of the bonding interface of the bamboo composite material provided by an embodiment of the present invention;

[0036] Figure 6 The bonding strength and bamboo material damage rate dot diagram of the bamboo composite material provided by the embodiments and comparative examples of the present invention;

[0037] Figure 7 The elastic modulus and static bending strength point diagram of the bamboo composite material provided in the embodiments and comparative examples of the present invention.

[0038] In the figure: 1. electrode plate; 2. wood or bamboo board; 3. adhesive. DETAILED DESCRIPTION

[0039] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0040] The mechanical property tests performed on the embodiments or comparative examples of the present invention include bonding strength test, bamboo breakage rate test, elastic modulus test and static bending strength test, and the test method is carried out with reference to GB / T 17657-2022 "Test methods for physical and chemical properties of artificial boards and veneer artificial boards".

[0041] The test method is:

[0042] The test method for the anti-corrosion performance test of the embodiments or comparative examples of the present invention is: after the samples provided by the embodiments or comparative examples are placed in the open air for 3 months, their weight loss percentage is measured, and the corrosion resistance grade is divided according to the weight loss percentage according to the anti-corrosion effect evaluation index provided in Table 1.

[0043] Table 1

[0044] Corrosion resistance grade Corrosion resistance Weight loss percentage Ⅰ Strong corrosion resistance 0%~10% Ⅱ Corrosion resistance 11%~24% Ⅲ Slightly resistant to decay 25%~44% Ⅳ Not resistant to corrosion 45%~70% V decay ＞70%

[0045] The test method for the mildew resistance performance test of the embodiment or comparative example of the present invention is: after placing the sample provided by the embodiment or comparative example in the open air for 3 months, the area of ​​the surface infected hyphae is measured, and the mildew resistance grade is divided according to the mildew resistance effect evaluation index provided in Table 2 according to the area of ​​the surface infected hyphae.

[0046] Table 2

[0047] Mildew resistance level Infected hyphae area on the sample surface 0 0 1 ＜1 / 4 2 1 / 4~1 / 2 3 1 / 2~3 / 4 4 3 / 4~1 5 1

[0048] Example 1

[0049] This embodiment provides a bamboo composite material and a preparation method thereof, the preparation method comprising:

[0050] (1) The bamboo board is sanded with a sanding amount of 0.5 mm;

[0051] (2) The bamboo board is subjected to humidity control treatment to make the moisture content of the bamboo board 15%, and is placed in a constant temperature and humidity chamber for one week to make the moisture content of the bamboo board uniform;

[0052] (3) If Figure 1 As shown, two silver plates are placed on the upper and lower sides of the bamboo board after humidity conditioning in the thickness direction, the silver content of the silver plate is 92.5%, the board surface pressure is set to 0.1MPa at room temperature, one side of the silver plate is connected to the negative electrode of the high-voltage electric field generator, and the other side of the silver plate is grounded, and the positive and negative voltage difference is set to 40 kV. After the treatment time is 6 hours, the connection mode of the two silver plates is swapped, and the high-voltage electric field surface treatment is continued for 6 hours;

[0053] (4) The surface of the bamboo board after the high-voltage electric field surface treatment is coated with a phenolic resin adhesive, the viscosity of the phenolic resin adhesive is 346 mPa·s, and the solid content is 45%. The bamboo boards are stacked in pairs, with the yellow bamboo sides facing each other, to obtain bamboo board blanks;

[0054] (5) The bamboo board blank was placed in a hot press, where the hot pressing temperature was set to 140°C, the hot pressing time was 1 min / mm, and the hot pressing pressure was 1 MPa. During the hot pressing process, metal plates were placed on the upper and lower sides of the blank, one side was connected to the negative electrode of the high-voltage electric field generator, and the other side of the metal plate was connected to the positive electrode. The voltage difference between the positive and negative electrodes was set to 60 kV, and the processing time was the same as the hot pressing time to obtain a bamboo composite material.

[0055] (6) After the treatment is completed, turn off the high-voltage electric field generator, and remove the bamboo composite material after decompression.

[0056] Comparative Example 1

[0057] This comparative example provides a bamboo composite material and a preparation method thereof. Different from Example 1, in this comparative example, the bamboo board after humidity conditioning treatment is not subjected to high-voltage electric field surface treatment in step (3), and the process directly jumps to step (4).

[0058] Comparative Example 2

[0059] This comparative example provides a bamboo composite material and a preparation method thereof. Different from Example 1, in this comparative example, step (5) is: placing the bamboo board blank into a hot press, wherein the hot pressing temperature is set to 140°C, the hot pressing time is 1 min / mm, and the hot pressing pressure is 1 MPa.

[0060] Comparative Example 3

[0061] This comparative example provides a bamboo composite material and a preparation method thereof. Different from Example 1, in this comparative example, the bamboo board after humidity conditioning treatment is not subjected to high-voltage electric field surface treatment in step (3), and the process directly jumps to step (4), and step (5) is: placing the bamboo board blank into a hot press, wherein the hot pressing temperature is set to 140°C, the hot pressing time is 1 min / mm, and the pressure during hot pressing is 1 MPa.

[0062] The bamboo composite materials prepared in Example 1 and Comparative Examples 1-3 were cooled to room temperature, and then their mechanical properties and anti-corrosion properties were tested respectively. The mechanical properties test included a bonding strength test, a bamboo breakage rate test, an elastic modulus test, and a static bending strength test. The test results are shown in FIG. Figure 6 and Figure 7 As shown in Table 3, the test results are integrated.

[0063] Table 3

[0064] Bonding strength / MPa Bamboo breakage rate / % Elastic modulus / GPa Static bending strength / GPa Corrosion resistance grade Example 1 11.3 69.8 9.5 117.4 Ⅱ Comparative Example 1 9.6 58.7 8.7 107.5 Ⅳ Comparative Example 2 8.3 36.2 7.2 90.1 Ⅱ Comparative Example 3 7.5 29.5 6.2 84.3 V

[0065] As shown in Table 3, the bamboo composite material provided in Example 1 has higher bonding strength, bamboo slope, elastic modulus and static bending strength than all the comparative examples, which proves that the bamboo composite material provided in Example 1 has good mechanical properties, and the bonding strength fully meets the practical requirements. The decay resistance level of the bamboo composite material provided in Example 1 is the same as that of Comparative Example 2, and is higher than that of Comparative Example 1 and Comparative Example 3. This is because both Example 1 and Comparative Example 1 are subjected to high-voltage electric field surface treatment, so that nano-metal particles are generated on the surface, thereby improving the decay resistance level of the bamboo composite material.

[0066] Figure 3 The relationship between the viscosity and frequency of the adhesive of the bamboo composite material prepared in Example 1 and Comparative Examples 1-3, the viscosity of the adhesive is significantly increased in the frequency range due to different treatment steps. The change in Example 1 is more obvious, which is mainly due to the surface effect of the nanosilver particles, which are easy to combine with the phenoxy anion, further improving the crosslinking degree of the phenolic resin. At the same time, during the high-voltage electric field treatment, new chemical groups such as electrons, hydrogen ions, oxygen ions and hydroxyl groups are significantly increased, and these chemical groups collide with the adhesive liquid, which is conducive to increasing the content of hydroxymethyl.

[0067] The storage modulus and loss modulus of the bamboo composite materials prepared in Example 1 and Comparative Examples 1-3 were tested respectively as a function of frequency. The test results are as follows: Figure 4 As shown, the crossover point under the synergistic effect of Example 1 is the lowest, which indicates that the higher the molecular weight of the adhesive, the higher the polycondensation reaction of the adhesive and the stronger the strength. Therefore, the effect of the method described in this patent on the reaction characteristics of the adhesive is confirmed.

[0068] Figure 5The cross-section and longitudinal section micrographs of the bonding interface of the bamboo composite material prepared in Example 1 and Comparative Examples 1-3, wherein the arrows are marked as the ineffective penetration positions of the adhesive, and the circles are the effective penetration positions of the adhesive. As can be seen from the figure, the distribution of the bonding interface of the bamboo composite material prepared in Example 1 is orderly and continuous, the average penetration depth of the adhesive is reduced, but the effective penetration depth is increased. It is further confirmed that the method described in this patent can increase the polymerization speed of the adhesive, inhibit the ineffective penetration of the adhesive at the bonding interface, and thus improve the comprehensive mechanical properties of the bamboo composite material.

[0069] Figure 6 The bonding strength and bamboo material damage rate dot diagram of the bamboo composite material provided by the embodiments and comparative examples of the present invention; Figure 7 The elastic modulus and static bending strength point diagram of the bamboo composite material provided by the embodiments and comparative examples of the present invention. Figure 6 and Figure 7 It can be seen that the bamboo composite material prepared in Example 1 has the highest bonding strength, bamboo material destruction rate, elastic modulus and static bending strength, which proves that the bamboo composite material prepared in Example 1 has the best comprehensive mechanical properties. The method described in this patent can prepare high-strength, high-durability and antibacterial and antiseptic bamboo wood composite materials with excellent effects, and can effectively increase the added value of bamboo and wood materials.

[0070] Example 2

[0071] This embodiment provides a bamboo composite material and a preparation method thereof. Different from Embodiment 1, in this embodiment, the voltage difference between the positive and negative electrodes set in step (5) is 40 kV.

[0072] Example 3

[0073] This embodiment provides a bamboo composite material and a preparation method thereof. Different from Embodiment 1, in this embodiment, the voltage difference between the positive and negative electrodes set in step (5) is 20 kV.

[0074] The bamboo composite materials prepared in Examples 1-3 and Comparative Example 2 were cooled to room temperature, and then the bonding strength, anticorrosive performance and anti-mildew performance were tested respectively. The test results are shown in Table 4.

[0075] Table 4

[0076] High voltage electric field voltage value / kV Bonding strength / MPa Corrosion resistance grade Mildew resistance level Example 1 60 11.3 Ⅱ 1 Example 2 40 9.8 Ⅲ 2 Example 3 20 8.9 Ⅲ 3 Comparative Example 2 / 8.3 Ⅱ 2

[0077] As shown in Table 4, the bonding strength, decay resistance and mildew resistance of the bamboo composite material provided in Example 1 are higher than those of other examples. This is mainly because the higher the voltage value of the high-voltage electric field, the greater its inductive effect on the adhesive. At the same time, the high-voltage electric field also has a certain sterilization function. The higher the voltage value of the high-voltage electric field, the better the sterilization effect.

[0078] Example 4

[0079] The present embodiment provides a bamboo composite material and a preparation method thereof. Different from the embodiment 1, in the present embodiment, step (3) is: placing two silver plates respectively on the upper and lower sides of the bamboo plate in the thickness direction after the humidity conditioning treatment, the silver content of the silver plates is 95.0%, the plate surface pressure is set to 0.1 MPa under room temperature, one side of the silver plate is connected to the negative electrode of the high-voltage electric field generator, and the other side of the silver plate is connected to the positive electrode, and the positive and negative voltage difference is set to 20 kV. After the treatment time is 3 hours, the connection mode of the two silver plates is swapped, and the high-voltage electric field surface treatment is continued for 3 hours.

[0080] Example 5

[0081] This embodiment provides a bamboo composite material and a preparation method thereof. Different from Embodiment 4, in this embodiment, the voltage difference between the positive and negative electrodes set in step (3) is 20 kV. After the treatment time is 6 hours, the connection mode of the two silver plates is reversed, and the high-voltage electric field surface treatment is continued for 6 hours.

[0082] Example 6

[0083] This embodiment provides a bamboo composite material and a preparation method thereof. Different from Embodiment 4, in this embodiment, the voltage difference between the positive and negative electrodes set in step (3) is 20 kV. After the treatment time is 12 hours, the connection mode of the two silver plates is reversed, and the high-voltage electric field surface treatment is continued for 12 hours.

[0084] Example 7

[0085] This embodiment provides a bamboo composite material and a preparation method thereof. Different from Embodiment 4, in this embodiment, the voltage difference between the positive and negative electrodes set in step (3) is 40 kV. After the treatment time is 3 hours, the connection mode of the two silver plates is reversed, and the high-voltage electric field surface treatment is continued for 3 hours.

[0086] Example 8

[0087] This embodiment provides a bamboo composite material and a preparation method thereof. Different from Embodiment 4, in this embodiment, the voltage difference between the positive and negative electrodes set in step (3) is 40 kV. After the treatment time is 6 hours, the connection mode of the two silver plates is reversed, and the high-voltage electric field surface treatment is continued for 6 hours.

[0088] Example 9

[0089] This embodiment provides a bamboo composite material and a preparation method thereof. Different from Embodiment 4, in this embodiment, the voltage difference between the positive and negative electrodes set in step (3) is 40 kV. After the treatment time is 12 hours, the connection mode of the two silver plates is reversed, and the high-voltage electric field surface treatment is continued for 12 hours.

[0090] Example 10

[0091] This embodiment provides a bamboo composite material and a preparation method thereof. Different from Embodiment 4, in this embodiment, the voltage difference between the positive and negative electrodes set in step (3) is 60 kV. After the treatment time is 3 hours, the connection mode of the two silver plates is reversed, and the high-voltage electric field surface treatment is continued for 3 hours.

[0092] Embodiment 11

[0093] This embodiment provides a bamboo composite material and a preparation method thereof. Different from Embodiment 4, in this embodiment, the voltage difference between the positive and negative electrodes set in step (3) is 60 kV. After the treatment time is 6 hours, the connection mode of the two silver plates is reversed, and the high-voltage electric field surface treatment is continued for 6 hours.

[0094] Example 12

[0095] This embodiment provides a bamboo composite material and a preparation method thereof. Different from Embodiment 4, in this embodiment, the voltage difference between the positive and negative electrodes set in step (3) is 60 kV. After the treatment time is 12 hours, the connection mode of the two silver plates is reversed, and the high-voltage electric field surface treatment is continued for 12 hours.

[0096] The bamboo composite materials prepared in Examples 4-12 and Comparative Example 3 were cooled to room temperature, and then the bonding strength, anticorrosive performance and anti-mildew performance were tested respectively. The test results are shown in Table 5.

[0097] Table 5

[0098] High voltage electric field voltage value / kV High voltage treatment time / h Bonding strength / MPa Corrosion resistance grade Mildew resistance level Example 4 20 3+3 7.6 Ⅳ 4 Example 5 20 6+6 8.8 Ⅲ 3 Example 6 20 12+12 10.1 Ⅲ 2 Example 7 40 3+3 8.6 Ⅲ 3 Example 8 40 6+6 10.9 Ⅲ 2 Example 9 40 12+12 8.9 Ⅲ 2 Example 10 60 3+3 9.6 Ⅲ 2 Embodiment 11 60 6+6 11.6 Ⅱ 2 Example 12 60 12+12 6.9 Ⅱ 1 Comparative Example 3 / / 7.5 V 5

[0099] As shown in Table 5, by comparing Examples 4, 5 and 6, it is found that as the treatment time increases, the bonding performance, decay resistance and mildew resistance levels all increase. This is because as the pre-treatment time increases, the metal particle content increases, which is conducive to the increase of overall performance. By comparing Examples 7, 8, 9, 10, 11 and 12, it can be found that the bonding performance is higher when the treatment time is 6h+6h, but the decay resistance and mildew resistance levels gradually increase with time. This is mainly because the higher the metal particle content, the better the antibacterial effect, but too high a content has a negative effect on the bonding performance. Among them, Example 12 has the lowest bonding performance. This is mainly because as the treatment intensity increases, the metal content of the treated surface gradually increases, resulting in a decrease in the wettability of the material surface, the adhesive cannot be evenly distributed on the material surface, and an effective glue nail structure cannot be produced, resulting in a decrease in bonding strength.

[0100] The preparation method of the bamboo-wood composite material provided by the present invention forms nano-scale metal particles on the surface of the bamboo material by surface treatment of the bamboo material with a high voltage electric field. The nano-metal particles participate in the curing process of the adhesive. The bonding strength of the bamboo-wood composite material after treatment fully meets the requirements, and the mechanical properties of the bamboo-wood composite material prepared by the common bonding method are greatly improved. At the same time, the durability of the bamboo-wood composite material after treatment is more stable, and it has better antibacterial and anticorrosive properties, and is expected to be applied to related fields of high-performance bamboo-wood composite materials in the future.

[0101] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only used to explain the relative positional relationship, movement, etc. between the components in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly. It is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0102] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0103] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the enlightenment of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the purpose of the present invention and the claims, which all fall within the protection of the present invention.

Claims

1. A method for preparing a bamboo-wood composite material, characterized in that: include: Metal electrode plates are attached to two opposite sides of the wood and bamboo board, and a high voltage electric field is applied to the wood and bamboo board attached with the metal electrode plates to perform surface treatment; Applying glue to the pretreated wood and bamboo boards to form blanks to obtain blanks; Metal electrode plates are bonded to two opposite sides of the slab, and the slab bonded with the metal electrode plates is placed in a pressurizing device for pressurizing treatment. A high voltage electric field is applied to the slab during the pressurizing treatment, and a bamboo-wood composite material is obtained after the pressurizing treatment is completed.

2. The method for preparing the bamboo-wood composite material according to claim 1, characterized in that: Before laminating the metal electrode plates on the two opposite sides of the wood-bamboo board, the wood-bamboo board is also pre-treated, specifically including: The wood and bamboo board is sanded, wherein the sanding amount of the sanding treatment is 0.5-1 mm; The wood and bamboo boards are humidified to make the moisture content of the wood and bamboo materials 5-20%; Balancing treatment of wood and bamboo boards.

3. The method for preparing the bamboo-wood composite material according to claim 1, characterized in that: The metal electrode plates are bonded to two opposite sides of the wood and bamboo board, wherein the thickness of the metal electrode plates is not less than 0.5 mm, the purity is not less than 90%, and the board surface pressure of the wood and bamboo board is 0.1 MPa~0.5 MPa.

4. The method for preparing the bamboo-wood composite material according to claim 1, characterized in that: The material used for the metal electrode plate is selected from copper, silver or titanium.

5. The method for preparing the bamboo-wood composite material according to claim 1, characterized in that: The surface treatment of the wood and bamboo board bonded to the metal plate by applying a high-voltage electric field comprises connecting the metal electrode plates on both sides of the wood and bamboo board to the positive electrode and the negative electrode of the high-voltage electric field generator respectively, turning on the high-voltage electric field generator to apply a high-voltage electric field to perform surface treatment on the wood and bamboo board bonded to the metal plate, wherein the voltage difference between the positive electrode and the negative electrode is not less than 10 kV, and the surface treatment time is not less than 6 hours.

6. The method for preparing the bamboo-wood composite material according to claim 4, characterized in that: In the process of applying a high voltage electric field to the wood and bamboo board bonded to the metal plate for surface treatment, the electrodes connected to the metal electrode plates on both sides are interchanged, and the surface treatment is continued after changing the direction of application of the electric field.

7. The method for preparing the bamboo-wood composite material according to claim 1, characterized in that: The method of coating the pretreated wood and bamboo boards with glue and assembling them into blanks to obtain blanks includes assembling multiple wooden boards into a blank using an adhesive, wherein the adhesive used is selected from one or more of urea-formaldehyde resin, phenol-formaldehyde resin, resorcinol-phenol-formaldehyde resin and polyurethane.

8. The method for preparing the bamboo-wood composite material according to claim 1, characterized in that: The slab bonded with the metal electrode plate is placed in a pressurizing device for pressurizing treatment, and a high-voltage electric field is applied to the slab during the pressurizing treatment, including connecting the metal electrode plates on both sides of the slab to the positive and negative poles of the high-voltage electric field generator respectively, turning on the high-voltage electric field generator to apply a high-voltage electric field to perform surface treatment on the slab bonded with the metal plate, wherein the direction of the applied high-voltage electric field is colinear with the direction of pressurization, the voltage difference between the positive and negative poles of the high-voltage electric field generator is not less than 1 kV, and the treatment time is not less than 200 s.

9. The method for preparing the bamboo-wood composite material according to claim 1, characterized in that: The pressurizing temperature of the pressurizing treatment is 30° C. to 150° C., and the unit pressure on the surface of the slab is not less than 1 MPa.

10. A bamboo-wood composite material, characterized in that: Prepared by the method described in any one of claims 1 to 9.

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