A formaldehyde-free high-moisture-resistant anti-deformation full-bamboo shaving board and a preparation method thereof
By using multifunctional additives in the drying and/or gluing stages of bamboo particleboard, the reaction between bamboo fibers and lignin-based adhesives is promoted, solving the problems of moisture resistance and deformation resistance of bamboo particleboard, and realizing the application of bamboo materials with high environmental protection and low cost.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HUBEI HAOLAIKE CREATIVE HOME CO LTD
- Filing Date
- 2025-03-14
- Publication Date
- 2026-06-12
AI Technical Summary
Existing bamboo particleboard has shortcomings in moisture resistance and deformation resistance, and its traditional processes are complex, costly, and environmentally unfriendly, making it difficult to widely use in the home building materials industry.
Multifunctional additives are used to treat bamboo shavings during the drying and/or gluing stages to promote the flow of bamboo fiber cell walls and chemical catalysis. Combined with lignin-based adhesives, formaldehyde-free, highly moisture-proof, and deformation-resistant all-bamboo particleboard is prepared.
It significantly improves the moisture resistance and deformation resistance of bamboo particleboard, enhances dimensional stability, meets high environmental protection standards, and the process is simple and can be implemented on conventional particleboard production lines.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of engineered wood products manufacturing technology, specifically to a formaldehyde-free, highly moisture-proof, and deformation-resistant all-bamboo particleboard and its preparation method. Background Technology
[0002] In recent years, bamboo particleboard, made from bamboo, has effectively solved the problems of low strength and easy swelling due to water absorption in traditional wood particleboard due to its high strength, high toughness, and low water absorption. However, the presence of numerous hydrophilic groups in bamboo cell walls and the tendency for large-format, ultra-long particleboard to bend and deform during use have become technical challenges that the home building materials industry urgently needs to overcome. Therefore, significant improvements and technological breakthroughs in the moisture resistance and deformation resistance of bamboo particleboard can accelerate the differentiated application of bamboo in the home building materials industry.
[0003] CN115805637A discloses a production process for high static bending strength particleboard, but it uses a combination of honeycomb particleboard substrate and resin-impregnated kraft paper for pressing, which is a complex process and requires special mold equipment.
[0004] CN116277323A discloses a method for preparing highly moisture-resistant bamboo particleboard, which involves immersing bamboo shavings in a paraffin-ammonia-soluble quaternary ammonium copper mixture for 1-2 hours before drying and then applying adhesive. However, the immersion treatment increases the moisture content of the shavings from 40% to 100%, significantly increasing the heat energy required for drying. Furthermore, the wet shavings need to be left to dry for a period of time, which is time-consuming and labor-intensive. In addition, particleboard factories typically do not have steaming tanks, further reducing the operability of this invention.
[0005] CN117621215A discloses a method for preparing highly moisture-resistant bamboo particleboard, but the bamboo chips need to undergo high-temperature and high-pressure carbonization at 180–220℃, 0.6–1.2 MPa, and for 2–4 hours. This process is difficult to achieve in conventional particleboard factories and is costly. In addition, the urea-formaldehyde resin used for adhesive application results in a high formaldehyde content in the board.
[0006] Therefore, it is urgent to solve the above problems and accelerate the application of bamboo in the home building materials industry. Summary of the Invention
[0007] To address the aforementioned technical problems, this invention aims to provide a formaldehyde-free, highly moisture-proof, and deformation-resistant all-bamboo particleboard and its preparation method, solving the current problems of all-bamboo particleboard being prone to water absorption and swelling, as well as bending and deformation. It also features simple processing, high industrial applicability, significant performance improvement, and environmental friendliness.
[0008] To achieve the above objectives, the first aspect of the present invention provides a first preparation method:
[0009] A method for preparing formaldehyde-free, highly moisture-proof, and deformation-resistant all-bamboo particleboard includes the following steps:
[0010] (1) Material preparation: Use raw bamboo or bamboo product processing residue as raw material. The moisture content of the raw material is 30-50%. The raw material is shaved and planed to obtain wet bamboo shavings.
[0011] (2) Drying: Spray the wet bamboo shavings obtained in step (1) with a multifunctional group additive and dry them to obtain dried bamboo shavings with a moisture content of 2.0 to 5.0%. The multifunctional group additive is used to promote the efficient flow of bamboo fiber cell walls and chemical catalysis.
[0012] (3) Screening: The dried bamboo shavings obtained in step (2) are sorted to obtain surface material and core material;
[0013] (4) Apply adhesive: Apply pure lignin-based adhesive or lignin-based adhesive modified by the multifunctional additive to the surface material and core material obtained in step (3), as well as waterproofing agent and curing agent, to obtain surface adhesive-mixed wood shavings and core adhesive-mixed wood shavings.
[0014] (5) Hot pressing: The surface layer shavings and core layer shavings obtained in step (4) are laid in layers according to a certain ratio, hot-pressed and cooled to obtain the board.
[0015] (6) Trimming: Trim the edges of the board obtained in step (5) to make the formaldehyde-free, moisture-proof and deformation-resistant all-bamboo particleboard.
[0016] The first preparation method proposed in this invention involves adding a specially formulated multifunctional group additive separately in the drying stage, or adding a specially formulated multifunctional group additive in both the drying stage and the sizing stage. This additive is composed of polyvinyl alcohol, terminal epoxy polyether silicone oil, dodecyl dimethyl ammonium chloride, vinyl polydimethylsiloxane, and water. This additive can promote the efficient flow and chemical catalysis of bamboo fiber cell walls, improve the reactivity of lignin-based adhesives with bamboo fibers, thereby enhancing the moisture resistance of the board, improving its resistance to deformation, and improving its dimensional stability.
[0017] Using lignin-based adhesives instead of traditional urea-formaldehyde resins in the gluing process ensures that the formaldehyde emission of the boards meets the high environmental protection standard of formaldehyde-free production.
[0018] The entire production process does not rely on special equipment or molds and can be implemented on conventional particleboard production lines, improving the factory's operability and economic efficiency.
[0019] The second aspect of the present invention provides a second preparation method:
[0020] A method for preparing formaldehyde-free, highly moisture-proof, and deformation-resistant all-bamboo particleboard includes the following steps:
[0021] (1) Material preparation: Use raw bamboo or bamboo product processing residue as raw material. The moisture content of the raw material is 30-50%. The raw material is shaved and planed to obtain wet bamboo shavings.
[0022] (2) Drying: The wet bamboo shavings obtained in step (1) are directly dried to obtain dried bamboo shavings with a moisture content of 2.0 to 5.0%.
[0023] (3) Screening: The dried bamboo shavings obtained in step (2) are sorted to obtain surface material and core material;
[0024] (4) Applying adhesive: Apply lignin-based adhesive modified with multifunctional group additives, waterproofing agent and curing agent to the surface material and core material obtained in step (3) respectively to obtain surface adhesive shavings and core adhesive shavings. The multifunctional group additives are used to promote the efficient flow and chemical catalysis of bamboo fiber cell walls.
[0025] (5) Hot pressing: The surface layer shavings and core layer shavings obtained in step (4) are laid in layers according to a certain ratio, hot-pressed and cooled to obtain the board.
[0026] (6) Trimming: Trim the edges of the board obtained in step (5) to make the formaldehyde-free, moisture-proof and deformation-resistant all-bamboo particleboard.
[0027] The second preparation method proposed in this invention involves adding a specially formulated multifunctional additive in the adhesive application stage. This additive is composed of polyvinyl alcohol, terminal epoxy polyether silicone oil, dodecyl dimethyl ammonium chloride, vinyl polydimethylsiloxane, and water. This additive can promote the efficient flow and chemical catalysis of bamboo fiber cell walls, improve the reactivity of lignin-based adhesives with bamboo fibers, thereby enhancing the moisture resistance, deformation resistance, and dimensional stability of the board.
[0028] Using lignin-based adhesives instead of traditional urea-formaldehyde resins in the gluing process ensures that the formaldehyde emission of the boards meets the high environmental protection standard of formaldehyde-free production.
[0029] The entire production process does not rely on special equipment or molds and can be implemented on conventional particleboard production lines, improving the factory's operability and economic efficiency.
[0030] The third aspect of the present invention is provided as follows:
[0031] A formaldehyde-free, highly moisture-proof, and deformation-resistant all-bamboo particleboard is prepared by either the first preparation method described above or the second preparation method described above.
[0032] The beneficial effects of this invention are as follows:
[0033] 1. By adding a specially formulated multifunctional group additive separately in the drying stage, or adding a specially formulated multifunctional group additive in both the drying and sizing stages, or adding a specially formulated multifunctional group additive separately in the sizing stage, the efficient flow and chemical catalysis of bamboo fiber cell walls can be promoted, the reactivity of lignin-based adhesives with bamboo fibers can be improved, thereby enhancing the moisture resistance, deformation resistance and dimensional stability of the board.
[0034] 2. Without significantly altering conventional drying and gluing processes, it significantly improves the moisture resistance and deformation resistance of the boards, and requires no special processing equipment or molds. The production process is simple and highly feasible for industrial production.
[0035] 3. The gluing process uses lignin-based adhesives instead of traditional urea-formaldehyde resins, ensuring that the formaldehyde emission of the boards meets high environmental protection standards with no added formaldehyde. Detailed Implementation
[0036] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art should understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available products.
[0037] This invention provides a method for preparing formaldehyde-free, highly moisture-proof, and deformation-resistant all-bamboo particleboard, comprising the following steps:
[0038] (1) Material preparation: Use raw bamboo or bamboo product processing residue as raw material. The moisture content of the raw material is 30-50%. The raw material is shaved and planed to obtain wet bamboo shavings.
[0039] (2) Drying: Spray the wet bamboo shavings obtained in step (1) with a multifunctional group additive and dry them to obtain dried bamboo shavings with a moisture content of 2.0 to 5.0%. The multifunctional group additive is used to promote the efficient flow of bamboo fiber cell walls and chemical catalysis.
[0040] (3) Screening: The dried bamboo shavings obtained in step (2) are sorted to obtain surface material and core material;
[0041] (4) Apply adhesive: Apply pure lignin-based adhesive or lignin-based adhesive modified by the multifunctional additive to the surface material and core material obtained in step (3), as well as waterproofing agent and curing agent, to obtain surface adhesive-mixed wood shavings and core adhesive-mixed wood shavings.
[0042] (5) Hot pressing: The surface layer shavings and core layer shavings obtained in step (4) are laid in layers according to a certain ratio, hot-pressed and cooled to obtain the board.
[0043] (6) Trimming: Trim the edges of the board obtained in step (5) to make the formaldehyde-free, moisture-proof and deformation-resistant all-bamboo particleboard.
[0044] In step (4) above, the surface material and core material obtained in step (3) are respectively coated with pure lignin-based adhesive or lignin-based adhesive modified with the multifunctional group additive, as well as waterproofing agent and curing agent, to obtain surface-coated wood shavings and core-coated wood shavings. That is, the surface material obtained in step (3) is respectively coated with pure lignin-based adhesive or lignin-based adhesive modified with the multifunctional group additive, as well as waterproofing agent, to obtain surface-coated wood shavings. And the core material obtained in step (3) is respectively coated with pure lignin-based adhesive or lignin-based adhesive modified with the multifunctional group additive, as well as waterproofing agent and curing agent, to obtain core-coated wood shavings. It should be noted that the surface material and the core material can be simultaneously applied with a pure lignin-based adhesive or simultaneously applied with a lignin-based adhesive modified by the multifunctional group additive, or one of the surface material and the core material can be applied with a pure lignin-based adhesive and the other with a lignin-based adhesive modified by the multifunctional group additive.
[0045] The multifunctional additives play an important role in the preparation process, improving the reactivity of lignin-based adhesives with bamboo fibers by promoting efficient flow and chemical catalysis of bamboo fiber cell walls.
[0046] Specifically, the multifunctional additive helps reduce the accumulation of internal stress in the board and effectively reduces the water absorption of the particleboard. Test results show that the 24-hour thickness swelling rate after water absorption is significantly reduced in the examples, proving that it contributes to better moisture resistance of the board.
[0047] The addition of the multifunctional additives and the pretreatment of bamboo shavings graft more active groups into the bamboo fibers, improving the reactivity of the bamboo fiber cell walls. This allows the cell walls of the bamboo shavings to soften effectively at high temperatures, making them easier to cross-link with lignin-based adhesives. Consequently, the board structure becomes more uniform, and its resistance to deformation is significantly improved. For example, key mechanical properties such as static bending strength and modulus of elasticity are enhanced.
[0048] After applying the multifunctional additive, the board samples showed smaller length and width changes under varying wet and dry conditions, indicating that the multifunctional additive can give the whole bamboo shavings board good dimensional stability, ensuring the stability and durability of the board in actual use.
[0049] In one embodiment, the multifunctional additive is prepared by mixing 30-40 parts of polyvinyl alcohol, 8-10 parts of terminal epoxy polyether silicone oil, 5-8 parts of dodecyl dimethyl ammonium chloride, 2-3 parts of vinyl polydimethylsiloxane, and 40-50 parts of water at 30-50°C and stirring at 300-400 r / min for 20-30 min.
[0050] The above-mentioned multifunctional additive formulation significantly improves the various properties of bamboo particleboard through the synergistic effect of its components. For example:
[0051] Polyvinyl alcohol, as a water-soluble polymer, provides good film-forming and adhesive properties with 30-40 parts of polyvinyl alcohol. This helps to enhance the bonding strength between lignin-based adhesives and bamboo fibers, improve the overall strength and density of the board, and also help to improve moisture resistance.
[0052] End-epoxy polyether silicone oil has good surface activity and lubricity. 8 to 10 parts of end-epoxy polyether silicone oil can form a protective film on the surface of bamboo fiber, reducing moisture penetration and promoting sliding between fibers. This is beneficial for uniform dispersion and full contact during fiber mixing and helps reduce excessive compressive stress during fiber laying.
[0053] Dodecyl dimethyl ammonium chloride, as a cationic surfactant, can neutralize the negative charge on the surface of bamboo fibers by adding 5-8 parts, promoting good dispersion between fibers, and also possessing certain antibacterial and antistatic functions. It improves the uniformity and stability of the mixture, prevents particle aggregation, and further reduces internal stress generated during hot pressing, thereby ensuring the consistency and reliability of the board structure.
[0054] Vinyl polydimethylsiloxane, as an organosilicon compound, exhibits excellent thermal stability and low surface tension in 2-3 parts. It maintains fluidity at high temperatures and reduces interfacial tension, promoting compatibility between different materials. During hot pressing, it helps achieve more uniform distribution and better cross-linking, further enhancing the mechanical properties of the sheet and the stability of its internal structural units.
[0055] Water is used as a solvent; 40 to 50 parts water ensure that other components can be fully dissolved and mixed evenly, ensuring the stability and ease of use of the additive system.
[0056] In one embodiment, in step (2), the amount of the multifunctional additive added is 1-3% of the mass of the wet bamboo shavings in an oven-dry state. Controlling the amount of the multifunctional additive added to 1.0-3.0% of the mass of the wet bamboo shavings in an oven-dry state not only helps to optimize the physical and mechanical properties of the board, such as static bending strength, modulus of elasticity, and internal bond strength, but also effectively improves its moisture resistance and dimensional stability, ensuring the stability and economy of the production process.
[0057] In one embodiment, the multifunctional group additive has a pH range of 6.5–7.5 and a solid content range of 46–53%. The pH range of 6.5–7.5, close to neutral, helps maintain a favorable reaction environment for the active groups in the bamboo fiber cell wall, facilitating the grafting reaction between the multifunctional group additive and the bamboo fiber, increasing the reactivity of the bamboo fiber, and allowing the bamboo shavings cell wall to soften effectively at high temperatures, making it easier to crosslink with lignin-based adhesives. The solid content range of 46–53% ensures sufficient effective components while avoiding operational difficulties due to excessively high solid content or adverse effects due to excessively low solid content. For example, when added in the drying stage, the small dosage and high solid content prevent excessive increase in the moisture content of the bamboo shavings, thus not affecting the subsequent drying process and energy consumption. By using multifunctional additives under appropriate pH and solid content conditions, it is possible to effectively reduce the accumulation of internal stress in the board, improve the board's moisture resistance (such as reducing the 24-hour water absorption thickness expansion rate), and resistance to deformation (such as improving dimensional stability, static bending strength, elastic modulus and internal bond strength), while maintaining the uniformity and stability of the board structure.
[0058] In one embodiment, in step (2), the drying temperature is 180–220°C, the drying medium is flue gas, and the moisture content of the dried bamboo shavings is 1.5–2.5%. At higher temperatures (180–220°C), multifunctional additives can react more effectively with bamboo fibers, increasing the grafting amount of active groups. This helps to improve the reactivity of the bamboo fiber cell walls, making them easier to crosslink with lignin-based adhesives. The moisture content of the dried bamboo shavings is controlled at 1.5%–2.5%, which is an optimized range that ensures good dispersibility and bonding effect of the adhesive during subsequent gluing, while preventing the bamboo fibers from becoming brittle due to excessively low moisture content, thus affecting the quality of the final board.
[0059] In one embodiment, in step (4), the amount of the multifunctional additive added is 0.1-0.5% of the mass of the wet bamboo shavings in an oven-dry state. Setting the amount of the multifunctional additive to 0.1-0.5% of the mass of the wet bamboo shavings in an oven-dry state allows for precise control of the reactivity between bamboo fiber and adhesive, optimizing the moisture resistance and dimensional stability of the board, while ensuring economic efficiency and environmental friendliness. Appropriate addition helps improve the dispersibility and flowability of the adhesive, enhancing the overall performance of the board, while also avoiding increased costs and environmental burden caused by excessive use. This range of addition amounts achieves optimal overall performance and production process efficiency.
[0060] In one embodiment, in step (4), the amount of pure lignin-based adhesive or lignin-based adhesive modified with multifunctional group additives is 6-8% of the mass of wet bamboo shavings in an oven-dry state, and the solid content of the pure lignin-based adhesive or the lignin-based adhesive modified with the multifunctional group additives is 40-53%. Controlling the amount of lignin-based adhesive or lignin-based adhesive modified with multifunctional group additives to 6-8% of the mass of wet bamboo shavings in an oven-dry state and the solid content to 40-53% ensures sufficient bonding strength and good processing performance. An appropriate amount of adhesive ensures sufficient bonding between bamboo shavings, improving the mechanical properties and durability of the board. Simultaneously, a suitable solid content helps optimize the flowability and drying efficiency during the adhesive application process, avoiding increased costs and environmental burden caused by excessive use. Parameter settings within this range achieve optimal overall performance and production efficiency.
[0061] In one embodiment, in step (4), the waterproofing agent is a fully refined solid paraffin wax and an emulsified emulsified paraffin wax liquid, with a solid content of 40-42%. The selection of fully refined solid paraffin wax and an emulsified emulsified paraffin wax liquid as the waterproofing agent, with a solid content set at 40-42%, aims to provide excellent waterproofing performance while ensuring good dispersibility and processability. The appropriate solid content ensures the uniform distribution of the waterproofing agent in the adhesive system, effectively reducing the water absorption rate of the bamboo particleboard, improving its moisture resistance and dimensional stability, thereby enhancing the overall durability and applicability of the board. The selection of fully refined solid paraffin wax and an emulsified emulsified paraffin wax liquid as the waterproofing agent is beneficial because it can form an effective waterproof protective film on the surface of bamboo shavings, reducing water penetration and improving the moisture resistance and dimensional stability of the board. The emulsified paraffin wax liquid also has good dispersibility and fluidity, facilitating uniform application and ensuring efficient and stable adhesive application. This combination not only improves the performance of the board but also meets environmental protection requirements.
[0062] In one embodiment, in step (4), a multifunctional additive, a waterproofing agent, a lignin-based adhesive, a curing agent, and water are applied sequentially to the surface layer material and the core layer material. This sequential application ensures that each additive fully utilizes its function and works synergistically. First, the multifunctional additive is added to enhance reactivity; then, the waterproofing agent is added to improve moisture resistance; subsequently, the lignin-based adhesive is applied to provide bonding strength; the curing agent accelerates the bonding process; and finally, water is used to adjust the fluidity of the mixture, ensuring uniform distribution and optimal bonding between the layers, thereby improving the overall performance and stability of the board.
[0063] In another embodiment, for the above preparation method, the multifunctional additive may be added only in the sizing stage, i.e.:
[0064] A method for preparing formaldehyde-free, highly moisture-proof, and deformation-resistant all-bamboo particleboard includes the following steps:
[0065] (1) Material preparation: Use raw bamboo or bamboo product processing residue as raw material. The moisture content of the raw material is 30-50%. The raw material is shaved and planed to obtain wet bamboo shavings.
[0066] (2) Drying: The wet bamboo shavings obtained in step (1) are directly dried to obtain dried bamboo shavings with a moisture content of 2.0 to 5.0%.
[0067] (3) Screening: The dried bamboo shavings obtained in step (2) are sorted to obtain surface material and core material;
[0068] (4) Applying adhesive: Apply lignin-based adhesive modified with multifunctional group additives, waterproofing agent and curing agent to the surface material and core material obtained in step (3) respectively to obtain surface adhesive shavings and core adhesive shavings. The multifunctional group additives are used to promote the efficient flow and chemical catalysis of bamboo fiber cell walls.
[0069] (5) Hot pressing: The surface layer shavings and core layer shavings obtained in step (4) are laid in layers according to a certain ratio, hot-pressed and cooled to obtain the board.
[0070] (6) Trimming: Trim the edges of the board obtained in step (5) to make the formaldehyde-free, moisture-proof and deformation-resistant all-bamboo particleboard.
[0071] The following examples will illustrate in detail the application of any of the preparation methods described above in industrial production:
[0072] Example 1—Adding a multifunctional group additive to the drying section
[0073] (1) The bamboo raw materials obtained by shaving and planing the original bamboo are health-preserved and piled up until the moisture content is about 30-40%, so that the moisture content of the bamboo shavings tends to be uniform and some starch and sugar substances are degraded.
[0074] (2) Prepare a multifunctional additive for use alone in the wood shavings drying section: Mix 35 parts by weight of polyvinyl alcohol, 8 parts by weight of epoxy polyether silicone oil, 6 parts by weight of dodecyl dimethyl ammonium chloride, 3 parts by weight of vinyl polydimethylsiloxane and 48 parts by weight of water and stir at 300 r / min for 20 min in a water bath at 40°C. The pH value is 6.5 and the solid content is 52.0%.
[0075] (3) At the bamboo shavings drying inlet, the multifunctional additive is sprayed evenly onto the surface of the bamboo shavings by spraying, with a dosage of 2.0% of the weight of the shavings in the oven-dried state. The flow rate of the nozzle is adjusted according to the belt conveyor speed. Due to the small dosage and high solid content, the moisture content of the bamboo shavings will not increase excessively or the drying energy consumption will be increased. During the conveying process of the drum dryer, the multifunctional additive on the surface penetrates downward, allowing the bamboo shavings, additive, and hot air to fully contact and be heated for heat treatment reaction. At the same time, the drum rotation speed and inlet and outlet temperatures are controlled, and the drying time is about 15 minutes.
[0076] (4) After the heat treatment reaction of the additives, the wet bamboo shavings are dried to a moisture content of about 2.5%, and the core and surface layers of dried bamboo shavings are obtained by air separation and super sieve. The surface shavings account for 40% of the total mass and are applied in layers: 8.0% lignin glue, 0.8% waterproofing agent, and 0.5% curing agent for the surface layer; 6.0% lignin glue, 0.6% waterproofing agent, and 0.5% curing agent for the core layer.
[0077] (5) The wet wood shavings after mixing with glue are laid in three layers of quantitative layer: surface-core-surface. Then, the finished bamboo formaldehyde-free particleboard is produced by hot pressing at 180-230℃, 4.5-1.7MPa in five stages and 8-10s / mm.
[0078] The formaldehyde-free, moisture-proof, and deformation-resistant bamboo particleboard prepared in Example 1 exhibits significantly improved moisture resistance, deformation resistance, and high environmental friendliness. By adding a multifunctional additive during the drying process, the reactivity of the lignin-based adhesive with bamboo fiber is enhanced, reducing the accumulation of internal stress in the board and making the board structure more uniform, thereby increasing static bending strength, modulus of elasticity, and internal bond strength. Furthermore, while ensuring high strength and excellent moisture resistance, this board maintains a high level of environmental friendliness by being formaldehyde-free, demonstrating highly environmentally friendly characteristics.
[0079] Example 2—Adding a multifunctional additive in the sizing stage
[0080] (1) The bamboo raw materials obtained by shaving and planing the original bamboo are health-preserved and piled up until the moisture content is about 30-40%, so that the moisture content of the bamboo shavings tends to be uniform and some starch and sugar substances are degraded.
[0081] (2) The wet bamboo shavings are dried to a moisture content of 2.5% by a pipe dryer, and then the core and surface dry bamboo shavings are obtained by air separation machine and super sieve.
[0082] (3) Prepare a multifunctional additive for use alone in the wood sizing process: Mix 35 parts by weight of polyvinyl alcohol, 10 parts by weight of epoxy polyether silicone oil, 7 parts by weight of dodecyl dimethyl ammonium chloride, 2 parts by weight of vinyl polydimethylsiloxane and 46 parts by weight of water and stir at 300 r / min for 20 min in a water bath at 40°C. The pH value is 6.5 and the solid content is 53.0%.
[0083] (4) Apply adhesive in layers according to the surface wood shavings accounting for 40% of the total weight. Adjust the position of the glue gun in the order of multifunctional additive, waterproofing agent, lignin adhesive, curing agent and water, and apply adhesive in sequence.
[0084] (5) The amount of surface layer multifunctional additive is 0.3%, waterproofing agent is 0.6%, lignin glue is 8.0%, and curing agent is 0.5%; the amount of core layer multifunctional additive is 0.3%, waterproofing agent is 0.4%, lignin glue is 6.0%, and curing agent is 0.5%.
[0085] (6) The wet wood shavings after mixing with glue are laid in three layers of quantitative layer: surface-core-surface. Then, the finished bamboo formaldehyde-free particleboard is produced by hot pressing at 180-230℃, 4.2-1.7MPa in five stages and 6-8s / mm.
[0086] The formaldehyde-free, moisture-proof, and deformation-resistant bamboo particleboard prepared in Example 2 exhibits significantly improved moisture resistance, deformation resistance, and high environmental friendliness. By adding a multifunctional additive during the adhesive application process, the reactivity of the lignin-based adhesive with bamboo fiber is enhanced, reducing the accumulation of internal stress and making the board structure more uniform, thereby increasing static bending strength, modulus of elasticity, and internal bond strength. Furthermore, while ensuring high strength and excellent moisture resistance, this board maintains a high level of environmental friendliness by being formaldehyde-free, demonstrating highly environmentally friendly characteristics.
[0087] Example 3—Combined addition of multifunctional additives in the drying and sizing stages
[0088] (1) The bamboo raw materials obtained by shaving and planing the original bamboo are health-preserved and piled up until the moisture content is about 30-40%, so that the moisture content of the bamboo shavings tends to be uniform and some starch and sugar substances are degraded.
[0089] (2) Prepare a multifunctional additive for use in the wood shavings drying section: Mix 32 parts by weight of polyvinyl alcohol, 9 parts by weight of epoxy polyether silicone oil, 6 parts by weight of dodecyl dimethyl ammonium chloride, 3 parts by weight of vinyl polydimethylsiloxane and 50 parts by weight of water and stir at 300 r / min for 20 min in a water bath at 40°C. The pH value is 6.5 and the solid content is 50.0%.
[0090] (3) At the bamboo shavings drying inlet, the multifunctional additive is sprayed evenly onto the surface of the bamboo shavings by spraying, with a dosage of 2.0% of the weight of the shavings in the oven-dried state. The flow rate of the nozzle is adjusted according to the belt conveyor speed. Due to the small dosage and high solid content, the moisture content of the bamboo shavings will not increase excessively or the drying energy consumption will be increased. During the conveying process of the drum dryer, the multifunctional additive on the surface penetrates downward, so that the bamboo shavings, additives and hot air can fully contact, be heated evenly, and have a full heat treatment reaction. At the same time, the drum rotation speed and inlet and outlet temperatures are controlled, and the drying time is about 15 minutes.
[0091] (4) The wet bamboo shavings after the heat treatment reaction of the additives are dried to a moisture content of about 2.5%, and the core and surface dry bamboo shavings are obtained by air separation machine and super sieve.
[0092] (5) Apply adhesive in layers according to the surface wood shavings weight ratio of 40%. Adjust the position of the glue gun in the order of multifunctional group additive, waterproofing agent, lignin adhesive, curing agent and water, and apply adhesive in sequence.
[0093] (6) The amount of surface layer multifunctional additive is 0.2%, the amount of waterproofing agent is 0.6%, the amount of lignin glue is 8.0%, and the amount of curing agent is 0.5%; the amount of core layer multifunctional additive is 0.2%, the amount of waterproofing agent is 0.4%, the amount of lignin glue is 6.0%, and the amount of curing agent is 0.5%.
[0094] (7) The wet wood shavings after mixing with glue are laid in three layers of quantitative layer: surface-core-surface. Then, the finished bamboo formaldehyde-free particleboard is produced by hot pressing at 180-230℃, 4.0-1.8MPa in five stages and 6-8s / mm.
[0095] The all-bamboo formaldehyde-free, highly moisture-proof, and deformation-resistant particleboard prepared in Example 3 exhibits significantly improved moisture resistance, deformation resistance, and high environmental friendliness. By jointly adding multifunctional additives in the drying and gluing stages, the reactivity of the lignin-based adhesive with bamboo fiber is significantly enhanced, reducing the accumulation of internal stress in the board and making the board structure more uniform, thereby strengthening static bending strength, modulus of elasticity, and internal bond strength. Furthermore, while ensuring high strength and excellent moisture resistance, this board maintains a high level of environmental friendliness by being formaldehyde-free, demonstrating highly environmentally friendly characteristics.
[0096] Comparison Example
[0097] (1) The bamboo raw materials obtained by shaving and planing the original bamboo are health-preserved and piled up until the moisture content is about 30-40%, so that the moisture content of the bamboo shavings tends to be uniform and some starch and sugar substances are degraded.
[0098] (2) The wet bamboo shavings are dried to a moisture content of 2.5% by a pipe dryer, and then the core and surface dry bamboo shavings are obtained by air separation machine and super sieve.
[0099] (3) Apply adhesive in layers according to the surface wood shavings accounting for 40% of the total weight, and apply the adhesive in the following order: waterproofing agent, lignin adhesive, curing agent, and water.
[0100] (4) The surface waterproofing agent dosage is 0.8%, the lignin glue dosage is 8.0%, and the curing agent dosage is 0.5%; the core waterproofing agent dosage is 0.6%, the lignin glue dosage is 6.0%, and the curing agent dosage is 0.5%; the solid content of the lignin glue adhesive is 52.0%.
[0101] (5) The wet wood shavings after mixing with glue are laid in three layers of quantitative layer: surface-core-surface. Then, the finished bamboo formaldehyde-free particleboard is produced by hot pressing at 180-230℃, 4.5-1.8MPa in five stages and 9-11s / mm.
[0102] The particleboard prepared in Examples 1-3 and the control example were tested according to the methods specified in GB / T 17657-2022 "Test Methods for Physical and Chemical Properties of Wood-based Panels and Decorative Wood-based Panels" 4.7, 4.11, 4.9, 4.6, and 4.35. The results are as follows:
[0103] Table 1
[0104]
[0105] Table 2
[0106]
[0107] Table 3
[0108]
[0109] The test results above show that whether multifunctional additives are added alone or in combination during the drying or sizing stages, they can promote efficient flow and chemical catalysis of bamboo fiber cell walls, effectively reducing the accumulation of internal stress in the board. This is manifested in the following ways:
[0110] (1) It improves the reactivity of lignin-based adhesives with bamboo fibers, effectively reduces the water absorption of particleboard, and improves the moisture resistance of the board. This can be seen in the three performance indicators: 24h water absorption thickness expansion rate, static bending strength after 70℃ immersion, and dimensional stability.
[0111] (2) The addition of multifunctional group additives and the pretreatment of bamboo shavings graft more active groups into bamboo fibers, which improves the reactivity of bamboo fiber cell walls, effectively softens the cell walls of bamboo shavings at high temperatures, makes it easier to cross-link and combine with lignin-based adhesives, and makes it easier to be densified, making the board structure more uniform. The static bending strength, elastic modulus and internal bond strength of the embodiment are all enhanced, which raises the base point for the board to resist stress relaxation and elastic creep in the later use process, and effectively improves the board's anti-deformation performance.
[0112] (3) The addition of multifunctional group additives did not affect the formaldehyde release of whole bamboo shavings, and it still maintained the high environmental protection of formaldehyde-free additives.
[0113] (4) Enhanced mechanical properties: The static bending strength, elastic modulus, and internal bond strength of Examples 1, 2, and 3 were all superior to those of the control example. In particular, Example 3 performed best in these indicators, indicating that the mechanical properties of the board can be more effectively improved by adding a multifunctional additive in the drying and sizing stages.
[0114] (5) Improved moisture resistance: The static bending strength after immersion at 70°C and the 24-hour water absorption thickness swelling rate showed that the examples with added multifunctional additives were significantly better than the control examples, indicating that the additives significantly improved the moisture resistance of the particleboard. For example, Example 3 had the lowest 24-hour water absorption thickness swelling rate, at only 3.46%, far lower than the 7.43% of the control example.
[0115] (6) Improved dimensional stability: Dimensional changes (dry shrinkage and wet expansion) tested under different humidity conditions showed that the addition of multifunctional additives helped improve the dimensional stability of the board. In particular, Example 3 showed the lowest dry shrinkage and wet expansion in both the L and W directions, demonstrating better dimensional stability.
[0116] (7) Maintaining high environmental protection: The formaldehyde release of all tested samples was 0.3mg / 100g, which meets the high environmental protection standard of formaldehyde-free addition. This shows that even if multifunctional group additives are added, the environmental performance of the board is not affected, ensuring its safety and environmental protection as a formaldehyde-free product.
[0117] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and concept of the present invention, should be covered within the scope of protection of the present invention.
Claims
1. A method for preparing formaldehyde-free, highly moisture-proof, and deformation-resistant all-bamboo particleboard, characterized in that, Includes the following steps: (1) Material preparation: Use raw bamboo or bamboo product processing residue as raw material. The moisture content of the raw material is 30-50%. The raw material is shaved and planed to obtain wet bamboo shavings. (2) Drying: The wet bamboo shavings obtained in step (1) are sprayed with a multifunctional group additive and dried to obtain dried bamboo shavings with a moisture content of 2.0-5.0%. The multifunctional group additive is prepared by mixing 30-40 parts of polyvinyl alcohol, 8-10 parts of terminal epoxy polyether silicone oil, 5-8 parts of dodecyl dimethyl ammonium chloride, 2-3 parts of vinyl polydimethylsiloxane and 40-50 parts of water at 30-50°C and stirring at 300-400 r / min for 20-30 min. It is used to promote the efficient flow of bamboo fiber cell walls and chemical catalysis. The amount of the multifunctional additive added is 1-3% of the mass of wet bamboo shavings in an absolutely dry state, the pH range is 6.5-7.5, and the solid content ranges from 46% to 53%. (3) Screening: The dried bamboo shavings obtained in step (2) are sorted to obtain surface material and core material; (4) Apply adhesive: Apply the lignin-based adhesive modified with the multifunctional group additive to the surface material and core material obtained in step (3), as well as waterproofing agent and curing agent, to obtain surface adhesive shavings and core adhesive shavings. (5) Hot pressing: The surface layer shavings and core layer shavings obtained in step (4) are laid in layers according to the ratio, hot pressed into shape, and cooled to obtain the board; (6) Trimming: Trim the edges of the board obtained in step (5) to make the formaldehyde-free, moisture-proof and deformation-resistant all-bamboo particleboard.
2. The method for preparing formaldehyde-free, highly moisture-proof, and deformation-resistant all-bamboo particleboard according to claim 1, characterized in that, In step (2), the drying temperature is 180-220℃, the drying medium is flue gas, and the moisture content of the dried bamboo shavings is 1.5-2.5%.
3. The method for preparing formaldehyde-free, highly moisture-proof, and deformation-resistant all-bamboo particleboard according to claim 1, characterized in that, In step (4), the amount of multifunctional additive added is 0.1 to 0.5% of the mass of wet bamboo shavings in an absolutely dry state.
4. The method for preparing formaldehyde-free, highly moisture-proof, and deformation-resistant all-bamboo particleboard according to claim 1, characterized in that, In step (4), the amount of lignin-based adhesive modified with multifunctional group additives is 6-8% of the mass of wet bamboo shavings in an oven-dry state, and the solid content of the lignin-based adhesive modified with the multifunctional group additives is 40-53%.
5. The method for preparing formaldehyde-free, highly moisture-proof, and deformation-resistant all-bamboo particleboard according to claim 1, characterized in that, In step (4), the waterproofing agent is fully refined solid paraffin and emulsified emulsified paraffin liquid, with a solid content of 40-42%.
6. The method for preparing formaldehyde-free, highly moisture-proof, and deformation-resistant all-bamboo particleboard according to claim 1, characterized in that, In step (4), the multifunctional additive, waterproofing agent, lignin-based adhesive, curing agent and water are applied sequentially to the surface material and the core material.
7. A formaldehyde-free, highly moisture-proof, and deformation-resistant all-bamboo particleboard, characterized in that, It is obtained by the preparation method according to any one of claims 1-6.