Preparation method of environment-friendly low-carbon reconstituted bamboo

Abstract

The application discloses a kind of preparation methods of environment-friendly low-carbon recombination bamboo, comprising the following steps: S1, select bamboo and bamboo silk fiber, remove the impurities on the surface of the bamboo, the bamboo is completely soaked in water until bamboo is in saturated state, the bamboo is subjected to multiple freeze-thaw cycle treatment, and the pretreated bamboo strip with crack is obtained;S2, the pretreated bamboo strip obtained in step S1 is dried, and the crack on the surface of the pretreated bamboo strip is expanded, and the prepared bamboo strip with more obvious crack is obtained;S3, select low-pressure air injection device, clean along the crack direction of the surface of the prepared bamboo strip, and obtain clean and dry preparable bamboo strip;To enhance the electrostatic adsorption capacity of bamboo silk fiber, ensure that the adhesive and fiber filled in the crack can be closely combined, improve the stability of bamboo, reduce the deformation, cracking and other problems caused by environmental changes.

Description

Technical Field

[0001] This invention relates to a method for preparing reconstituted bamboo, and more particularly to a method for preparing environmentally friendly and low-carbon reconstituted bamboo. Background Technology

[0002] Reconstituted bamboo, also known as resilient bamboo, is a new bamboo material that is reorganized and strengthened. Its production process involves processing bamboo into long strips, shreds, or crushed bundles, drying them, impregnating them with resin, drying them again to the required moisture content, and then laying them in a mold for high-temperature, high-pressure thermosetting. Reconstituted bamboo possesses many excellent properties. First, it has a certain degree of natural corrosion resistance, which is further enhanced through carbonization and preservative treatments. The weight loss rate of treated reconstituted bamboo boards is relatively low, demonstrating strong corrosion resistance. Furthermore, reconstituted bamboo exhibits excellent dimensional stability and aging resistance. Due to its unique properties, reconstituted bamboo has been widely used in various fields. It is widely used in construction, outdoor furniture, flooring, and even for specific applications such as wind turbine blades, building beams and columns, and landscaping.

[0003] Existing technology CN113528074A discloses a polyurethane adhesive, its preparation method, and its application in the preparation of reconstituted bamboo, as well as reconstituted bamboo. The method for preparing reconstituted bamboo includes the following steps: mixing polyurethane adhesive with water to obtain a glue; soaking bamboo fibers in the glue to obtain wet bamboo fibers; drying and balancing the moisture content of the wet bamboo fibers to obtain dry bamboo fibers; placing the dry bamboo fibers in a mold for installation and then pressing to obtain a bamboo board; curing the bamboo board and demolding to obtain reconstituted bamboo. However, this existing technology has the following technical problems:

[0004] (1) The preparation process of reconstituted bamboo is simply a process of applying glue to bamboo fibers and then curing them. Therefore, it is difficult to effectively improve the mechanical properties of the reconstituted bamboo.

[0005] (2) Furthermore, the preparation process of this reconstituted bamboo requires the use of a large amount of glue and other adhesives, making it difficult to accurately control the formaldehyde and other harmful gases contained in the reconstituted bamboo, which does not meet the requirements of low-carbon and environmentally friendly development in modern society.

[0006] Therefore, there is an urgent need for an environmentally friendly and low-carbon method for preparing reconstituted bamboo to solve the above-mentioned technical problems. Summary of the Invention

[0007] This invention overcomes the shortcomings of the prior art and provides a method for preparing environmentally friendly and low-carbon reconstituted bamboo.

[0008] To achieve the above objectives, the technical solution adopted by this invention is: a method for preparing environmentally friendly and low-carbon reconstituted bamboo, comprising the following steps:

[0009] S1. Select bamboo and bamboo fiber, remove impurities from the surface of the bamboo, completely immerse the bamboo in water until it is saturated, and perform multiple freeze-thaw cycles on the bamboo to obtain pre-treated bamboo strips with cracks.

[0010] S2, the pretreated bamboo strips obtained in step S1 are dried, and the cracks on the surface of the pretreated bamboo strips are expanded to obtain pre-prepared bamboo strips with more obvious cracks.

[0011] S3, Select a low-pressure air jet device to clean along the crack direction on the surface of the pre-prepared bamboo strip to obtain clean and dry bamboo strips ready for preparation;

[0012] S4, electrostatically treat the bamboo fiber and the bamboo strip to be prepared, control the distance between the cracks of the bamboo fiber and the bamboo strip to be prepared, and rely on electrostatic force to adsorb the bamboo fiber into the crack;

[0013] S5, use an adhesive to fix the bamboo fibers in the cracks and fill the cracks on the surface of the bamboo material to obtain reconstituted bamboo.

[0014] In a preferred embodiment of the present invention, in step S1, the bamboo is completely immersed in water for 2 to 72 hours; the bamboo undergoes at least 3 freeze-thaw cycles. Impurities on the surface of the bamboo include stains, soil, and irregular portions of the bamboo.

[0015] In a preferred embodiment of the present invention, in step S2, the drying method of the pretreated bamboo strip is natural air drying, and the method for treating the expansion of surface cracks on the pretreated bamboo strip is mechanical hammering or knife expansion.

[0016] In a preferred embodiment of the present invention, the mechanical striking method involves an operator using a hammer-like tool to slowly and evenly strike the surface of the bamboo, while the knife expansion method involves an operator using a utility knife or carving knife to gently scrape along the crack, thereby expanding the crack on the surface of the bamboo strip.

[0017] In a preferred embodiment of the present invention, in step S3, the pre-prepared bamboo strip is placed in a dry and clean area, and the surface of the pre-prepared bamboo strip is pre-cleaned using the low-pressure air jet device. The nozzle of the low-pressure air jet device and the pressure of the ejected gas are adjusted, and the surface of the pre-prepared bamboo strip is cleaned again along the crack direction.

[0018] In a preferred embodiment of the present invention, the low-pressure air jet device has two different air pressure conditions. The first air pressure condition acts on the surface of the pre-prepared bamboo strip to clean dust and impurities adhering to the surface of the pre-prepared bamboo strip; the second air pressure condition acts on the cracks on the surface of the pre-prepared bamboo strip to clean moisture and air bubbles contained within the cracks. This ensures that both the surface of the pre-prepared bamboo strip and the interior of the cracks are in a dry and clean state.

[0019] In a preferred embodiment of the present invention, in step S4, the method for electrostatic treatment of the cracks in the bamboo strip and the bamboo fiber is to use an electrostatic generator or a high-voltage electric field.

[0020] In a preferred embodiment of the present invention, in step S4, a chemical reagent with electrostatic adsorption properties is added to the cracks in the bamboo strip preparation, and an antistatic agent is coated on the surface of the bamboo fibers. This further increases the electrostatic adsorption force between the crack surface and the bamboo fibers.

[0021] In a preferred embodiment of the present invention, in step S4, the distance between the bamboo fiber and the crack in the bamboo material to be prepared is 2 to 5 mm.

[0022] In a preferred embodiment of the present invention, in step S5, the adhesive is white glue, a two-component adhesive, or one of the following: Xilin wood glue.

[0023] In a preferred embodiment of the present invention, step S1, the freeze-thaw cycle process includes the following steps:

[0024] S11, Place the saturated bamboo into a freezing device and keep it frozen for a period of time until the bamboo is completely frozen;

[0025] S12, transfer the completely frozen bamboo to room temperature until the bamboo is completely thawed;

[0026] S13, Repeat steps S11 and S12 sequentially with the completely thawed bamboo material for at least 3 cycles until the surface of the bamboo material develops numerous and uniform cracks, at which point the cycle stops.

[0027] In a preferred embodiment of the present invention, the temperature of the frozen state is -10 to -20°C, and the time the bamboo is in the frozen state is 5 to 24 hours.

[0028] This invention addresses the shortcomings of the prior art and has the following beneficial effects:

[0029] (1) The reconstituted bamboo preparation method provided by this invention involves completely immersing the bamboo in water during the preparation process. After the bamboo has fully absorbed water, it undergoes repeated freezing and thawing treatments, causing the internal stress of the bamboo to continuously increase. This results in cracks appearing on the surface of the bamboo due to changes in internal stress, ensuring the uniformity of crack formation. Simultaneously, a low-pressure air jet device not only removes impurities and dust from the surface of the bamboo in a timely and thorough manner but also removes moisture and air bubbles from the cracks by adjusting the jet pressure and nozzle angle, ensuring that both the surface and interior of the cracks are dry, which is beneficial for the effect of electrostatic force. Furthermore, by expanding the cracks on the surface of the bamboo, the electrostatic adsorption capacity of the bamboo fibers is enhanced, ensuring that the adhesive and fibers filling the cracks are tightly bonded. This effectively enhances the compressive, tensile, and bending strengths of the bamboo, improves its stability, and reduces the occurrence of deformation and cracking caused by environmental changes. This solves the problem of ensuring the various mechanical properties of reconstituted bamboo in the prior art.

[0030] (2) The preparation method provided by this invention uses a low-pressure air jetting device to clean the surface of the bamboo and the interior of the cracks during the preparation process. This not only allows for precise control of the pressure and direction of the jetting gas, ensuring a fine and efficient process, but also provides a clean environment for the subsequent adsorption of bamboo fibers and the filling of adhesives. Simultaneously, the low-pressure air jetting device thoroughly removes residual moisture and air bubbles from the cracks, effectively preventing interference from moisture and air bubbles on electrostatic adsorption, improving adsorption efficiency, and ensuring the final curing effect. This further solves the problem in existing technologies where it is difficult to guarantee the various mechanical properties of reconstituted bamboo.

[0031] (3) The preparation method provided by this invention further expands the formed cracks during the preparation process, thereby providing a good foundation for subsequent electrostatic treatment. It also increases the adsorption force between the bamboo fibers and the cracks, improving adsorption efficiency and ensuring that the bamboo fibers are firmly adsorbed into the cracks. Furthermore, a gelling agent is used to fix them, achieving a tight bond between the bamboo fibers and the bamboo material. This solves the problem of excessive use of adhesives such as glue in existing technologies, thereby reducing the generation and release of harmful gases such as formaldehyde, and meeting the requirements of modern low-carbon and environmentally friendly development. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a schematic diagram of the process structure for preparing recombinant bamboo according to the present invention;

[0034] Figure 2 This is a schematic diagram of the freezing and thawing cycle processing flow of the present invention. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein. Therefore, the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0037] like Figure 1 As shown, a method for preparing environmentally friendly, low-carbon reconstituted bamboo includes the following steps:

[0038] S1. Select bamboo and bamboo fiber, remove impurities from the surface of the bamboo, completely immerse the bamboo in water until it is saturated, and perform multiple freeze-thaw cycles on the bamboo to obtain pre-treated bamboo strips with cracks.

[0039] In step S1, the bamboo is completely immersed in water for 2 to 72 hours; the number of freeze-thaw cycles of the bamboo is not less than 3.

[0040] In step S1, as Figure 2 As shown, the freeze-thaw cycle process includes the following steps:

[0041] S11, Place the saturated bamboo into a freezing device and keep it frozen for a period of time until the bamboo is completely frozen;

[0042] S12, transfer the completely frozen bamboo to room temperature until the bamboo is completely thawed; the temperature of the frozen state is -10 to -20°C, and the time the bamboo is in the frozen state is 5 to 24 hours.

[0043] S13, Repeat steps S11 and S12 sequentially with the completely thawed bamboo material for at least 3 cycles until the surface of the bamboo material develops numerous and uniform cracks, at which point the cycle stops.

[0044] S2, the pretreated bamboo strips obtained in step S1 are dried, and the cracks on the surface of the pretreated bamboo strips are expanded to obtain pre-prepared bamboo strips with more obvious cracks.

[0045] In step S2, the drying method for the pretreated bamboo strips is natural air drying, and the method for treating the expansion of surface cracks in the pretreated bamboo strips is mechanical hammering or knife expansion.

[0046] S3. Select a low-pressure air jet device to clean along the crack direction on the surface of the pre-prepared bamboo strip to obtain clean and dry bamboo strips ready for preparation.

[0047] In step S3, the pre-prepared bamboo strip is placed in a dry and clean area, and the surface of the pre-prepared bamboo strip is pre-cleaned using the low-pressure air jet device. The nozzle of the low-pressure air jet device and the air pressure of the jetted gas are adjusted, and the surface of the pre-prepared bamboo strip is cleaned again along the crack direction.

[0048] S4, electrostatically treat the bamboo fiber and the bamboo strip to be prepared, control the distance between the cracks in the bamboo fiber and the bamboo strip to be prepared, and rely on electrostatic force to adsorb the bamboo fiber into the cracks.

[0049] In step S4, the electrostatic treatment of the cracks in the bamboo strips and the bamboo fibers is performed using an electrostatic generator and a high-voltage electric field. A chemical reagent with electrostatic adsorption properties is added to the cracks in the bamboo strips, and an antistatic agent is applied to the surface of the bamboo fibers. The distance between the bamboo fibers and the cracks in the bamboo material is 2–5 mm.

[0050] S5, use an adhesive to fix the bamboo fibers in the cracks and fill the cracks on the surface of the bamboo material to obtain reconstituted bamboo.

[0051] In step S5, the adhesive is white glue, a two-component adhesive, or one of the following: Xilin wood glue.

[0052] Example 1

[0053] Since bamboo harvested in autumn has reached maturity and its stems have hardened, exhibiting good structural stability, 250 kg of autumn bamboo was selected for use in this embodiment.

[0054] Cut the prepared bamboo into 50cm long sections, then remove soil stains, impurities, and irregular parts from the surface of the bamboo. After processing, put the bamboo sections into the soaking tank, ensuring that the water in the soaking tank can completely cover the bamboo.

[0055] Because bamboo is hard in autumn, in this embodiment, to ensure that the bamboo is fully saturated with water, it is soaked in water for 24 hours. After the bamboo is saturated with water, it is placed in a freezer at -15°C for 12 hours to ensure that the inside and outside of the bamboo are completely frozen.

[0056] Completely frozen bamboo is transferred to room temperature for natural thawing. During the thawing process, the water inside the bamboo begins to melt gradually, and the volume of water inside the bamboo begins to shrink continuously. However, due to the expansion of water in the ice crystal state, certain stress is formed inside the bamboo, thereby achieving the effect of destroying the internal structure of the bamboo.

[0057] By repeatedly performing the water-saturation, freezing, and thawing process on the bamboo five times, the internal stress of the bamboo is continuously increased. As a result, numerous and uniform cracks are generated on the surface of the bamboo.

[0058] To further deepen and widen the cracks, a rubber mallet was used to gently tap the bamboo that had already developed cracks. During the tapping process, the cracks on the bamboo surface were gradually widened. Afterwards, each bamboo strip was inspected manually, removing damaged bamboo and preserving the intact bamboo.

[0059] Adjust the nozzle of the low-pressure air jet device to emit gas pressure of 1.5 MPa to clean the bamboo surface, thereby removing dust and residual bamboo residue. Further adjust the nozzle to emit gas pressure of 0.8 MPa and adjust the nozzle orientation so that it is aimed at the cracks on the bamboo surface. Spray slowly and evenly along the cracks until any remaining moisture and air bubbles are completely removed from the cracks.

[0060] Both bamboo and bamboo fibers are placed in an electrostatic generator for electrostatic treatment, so that the cracks on the surface of the bamboo and the surface of the bamboo fibers are charged. Then, the bamboo fibers are placed 3mm away from the cracks in the bamboo. By utilizing the attraction between the electrostatic charges, the bamboo fibers are drawn into the cracks in the bamboo. In this embodiment, the amount of bamboo fibers drawn into the cracks is as high as 95.3%.

[0061] Finally, a white latex with good gap-filling properties and stability is evenly applied to the bamboo surface. The reconstituted bamboo is then placed in an environment with a temperature of 45℃ for natural curing, ensuring the curing of the white latex and a strong bond between the fibers and the bamboo. The result is environmentally friendly and low-carbon reconstituted bamboo.

[0062] According to the standards set in the national standard GB / T 40247-2021 "Reconstituted Bamboo", 100 bamboo samples were randomly selected from the reconstituted bamboo prepared in this embodiment for performance testing. Simultaneously, the formaldehyde released by the reconstituted bamboo was tested according to the standard "Formaldehyde Emission from Wood-based Panels and Their Products" (GB 18580-2017). The test results are shown in Table 1.

[0063]

[0064]

[0065] Table 1

[0066] In summary, by using the reconstituted bamboo preparation method provided in this application, not only can reconstituted bamboo with high compressive, tensile, and bending strength be prepared, thus improving the stability of bamboo materials, but the formaldehyde release during the use of reconstituted bamboo can also be reduced, thereby better meeting the requirements of low-carbon and environmental protection in modern social development. Therefore, this preparation method also has certain development prospects.

[0067] Comparative Example 1

[0068] Unlike Example 1, this comparative example omits the use of a low-pressure air jet device in step S3, and instead directly electrostatically treats the thawed and dried pre-prepared bamboo strips together with bamboo fibers. The remaining steps and parameters remain consistent, ultimately yielding reconstituted bamboo. Calculations show that only 78.4% of the bamboo fibers in this comparative example are absorbed into the cracks.

[0069] According to the standards set in the national standard GB / T 40247-2021 "Reconstituted Bamboo", 100 bamboo samples were randomly selected from the reconstituted bamboo prepared in this comparative example for performance testing. Simultaneously, the formaldehyde released by the reconstituted bamboo was tested according to the standard "Formaldehyde Emission from Wood-based Panels and Their Products" (GB 18580-2017). The test results are shown in Table 2.

[0070]

[0071]

[0072] Table 2

[0073] In summary, without using a low-pressure air jet device to clean the bamboo surface and cracks, the moisture and air bubbles in the cracks will interfere with the electrostatic adsorption process, significantly reducing the efficiency of bamboo fiber adsorption. Furthermore, the air bubbles in the cracks can cause voids during the adhesive application process, thus affecting the mechanical properties of the final reconstituted bamboo. However, the data shows that the reconstituted bamboo prepared by this method meets the formaldehyde emission standards of "Formaldehyde Emission from Interior Decoration and Renovation Materials—Artificial Boards and Their Products" (GB 18580-2017), further demonstrating that this preparation method aligns with the modern social concept of low-carbon and environmentally friendly development.

[0074] When using this invention, firstly, select appropriate bamboo, remove impurities, and cut it into sections; then, completely immerse the bamboo in water until it is saturated with water; then, place the saturated bamboo in a freezing device for a period of time to ensure that the bamboo is completely frozen; then, place the completely frozen bamboo at room temperature for thawing. During the thawing process, the expansion effect of water forming ice crystals will increase the internal stress of the bamboo after thawing. This stress can accumulate and increase under repeated freezing and thawing operations, resulting in more and more uniform cracks on the surface of the bamboo.

[0075] The cracks on the surface of bamboo are widened by using mechanical hammering or knife expansion methods to increase the depth and width of the cracks, so as to facilitate subsequent electrostatic treatment and adsorption of bamboo fibers. Furthermore, a low-pressure air jet device is used to remove moisture and air bubbles from the surface of bamboo and the cracks, thereby effectively avoiding the impact on subsequent adhesive curing.

[0076] Next, the cracked bamboo and bamboo fibers are electrostatically treated so that both the cracks and the surface of the bamboo fibers have static charges. Then, the bamboo fibers are brought close to the bamboo, and the bamboo fibers are attracted to the cracks by the electrostatic force. Finally, an adhesive is used to fix the position of the bamboo fibers to ensure a strong bond between the bamboo fibers and the bamboo.

[0077] Based on the preferred embodiments of the present invention described above, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A method for preparing environment-friendly low-carbon reconstituted bamboo, characterized in that, The method comprises the following steps: S1, selecting bamboo and bamboo fiber, removing impurities on the surface of the bamboo, soaking the bamboo in water until the bamboo is saturated, and performing multiple freeze-thaw cycle treatments on the bamboo to obtain pretreated bamboo strips with cracks; S2, drying the pretreated bamboo strips obtained in step S1 and expanding the cracks on the surface of the pretreated bamboo strips to obtain pretreated bamboo strips with more obvious cracks; S3, selecting a low-pressure air jet device to clean along the crack direction of the surface of the pretreated bamboo strips to obtain clean and dry preparable bamboo strips; S4, electrostatic treatment is performed on the bamboo fiber and the preparable bamboo strips respectively, the distance between the bamboo fiber and the cracks of the preparable bamboo strips is controlled, and the bamboo fiber is adsorbed into the cracks by electrostatic force; S5, using an adhesive to fix the bamboo fiber in the cracks and fill the cracks on the surface of the preparable bamboo to obtain reconstituted bamboo.

2. The method according to claim 1, wherein: In step S1, the bamboo is soaked in water for 2-72 hours, and the freeze-thaw cycle treatment is performed for not less than 3 times.

3. The method according to claim 1, wherein: In step S2, the drying treatment of the pretreated bamboo strips is natural air drying, and the expansion treatment of the cracks on the surface of the pretreated bamboo strips is mechanical knocking or knife expansion.

4. The method according to claim 1, wherein: In step S3, the pretreated bamboo strips are placed in a dry and clean area, the surface of the pretreated bamboo strips is pre-cleaned by the low-pressure air jet device, the nozzle of the low-pressure air jet device and the gas pressure of the ejected gas are adjusted, and the pretreated bamboo strips are cleaned again along the crack direction of the surface of the pretreated bamboo strips.

5. The method according to claim 1, wherein: In step S4, the electrostatic treatment of the cracks of the preparable bamboo strips and the bamboo fiber is performed by using an electrostatic generator in a high-voltage electric field.

6. The method according to claim 1, wherein: In step S4, a chemical reagent with electrostatic adsorption performance is added to the cracks of the preparable bamboo strips, and an antistatic agent is applied to the surface of the bamboo fiber.

7. The method according to claim 1, wherein: In step S4, the distance between the bamboo fiber and the cracks of the preparable bamboo is 2-5 mm.

8. The method according to claim 1, wherein: In step S5, the adhesive is one of white latex, two-component adhesive, and Xilin woodworking adhesive.

9. The method according to claim 1, wherein: In step S1, the freeze-thaw cycle treatment comprises the following steps: S11, put the bamboo in a water-saturated state into a freezing device and keep it in a frozen state for a period of time until the bamboo is completely frozen; S12, transfer the completely frozen bamboo to a normal temperature state until the bamboo is completely thawed; S13, repeatedly cycle the completely thawed bamboo through steps S11 and S12 for no less than 3 times until the bamboo surface produces more and uniform cracks.

10. The preparation method of the environmentally friendly low-carbon reconstituted bamboo according to claim 9, characterized in that: the temperature of the frozen state is -10 to -20 DEG C, and the bamboo is kept in the frozen state for 5 to 24 hours.

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