A recombined bamboo board carbonization and drawing integrated treatment process

Abstract

The present application relates to the technical field of reconstituted bamboo board processing, and particularly relates to a reconstituted bamboo board carbonization and wire drawing integrated treatment process. The process comprises the following steps: wire drawing activation, carbonization agent configuration, impregnation carbonization, crosslinking and curing, and drying and hot pressing. The carbonization agent comprises a functionalized ionic liquid, bis(3-formylphenyl) peroxydicarbonate, poly(glycidyl methacrylate-co-styrene), and N-methylpyrrolidone. The functionalized ionic liquid swells the bamboo filaments, realizes impurity degradation and cellulose crosslinking, and does not need to be impregnated with glue and traditional colorants, so that a reconstituted bamboo board with high strength, low expansion, antibacterial properties and suitable color is prepared. The process is environmentally friendly and efficient, and the carbonization agent can be recycled.

Description

Technical Field

[0001] This invention relates to the field of reconstituted bamboo board processing technology, and in particular to an integrated carbonization and wire drawing process for reconstituted bamboo boards. Background Technology

[0002] Reconstituted bamboo panels, as a high-performance bamboo composite material, are widely used in construction, furniture, and other fields due to their abundant raw materials and excellent mechanical properties. However, existing processing technologies still have many drawbacks: traditional high-temperature carbonization processes are energy-intensive and time-consuming, resulting in a bamboo quality loss rate of 10%-20%, and high temperatures can easily cause bamboo to become brittle, while also releasing large amounts of waste gas and liquid, polluting the environment; in chemical carbonization processes, commonly used carbonizing agents have poor compatibility with bamboo, leading to uneven penetration and incomplete degradation of impurities such as starch and protein, with residual components easily causing mold growth and affecting the corrosion resistance of the bamboo panels; in addition, existing processes often require additional glue impregnation to improve the bonding strength between bamboo fibers, which not only increases costs but may also release harmful substances from the adhesive, and the insufficient sealing of hydroxyl groups inside the bamboo fibers results in a high water absorption and swelling rate and poor dimensional stability in the finished product. Therefore, developing an integrated process that is low-energy-consumption, environmentally friendly, and can achieve efficient carbonization and stable cross-linking without glue impregnation has become an urgent need in the reconstituted bamboo panel processing field. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the existing technology and propose an integrated carbonization and wire drawing process for reconstituted bamboo boards.

[0004] To achieve the above objectives, the present invention provides an integrated carbonization and wire drawing process for reconstituted bamboo boards, comprising the following steps:

[0005] S1. Bamboo Fiber Activation: Select 3-5 year old moso bamboo, remove the nodes and outer skin, and cut the bamboo into sections with a length of 200-300mm. Use a double-roller bamboo fiber drawing machine at a speed of 200-300r / min to draw the bamboo sections into bamboo fibers with a thickness of 0.5-1mm and a width of 2-3mm. During the fiber drawing process, spray deionized water at a flow rate of 5-10mL / min to prevent the bamboo fibers from overheating. Place the drawn bamboo fibers into an ultrasonic cleaning tank (power 300-700W, frequency 10-20kHz), immerse the bamboo fibers in deionized water, and ultrasonically treat for 5-15 minutes. Remove and drain to obtain activated bamboo fibers.

[0006] S2. Preparation of carbonizing agent: Add functionalized ionic liquid to deionized water and stir for 30-40 min. Then add bis(3-formylphenyl) peroxide dicarbonate, poly(glycidyl methacrylate-co-styrene) and N-methylpyrrolidone in sequence and continue stirring for 1-2 h to obtain carbonizing agent.

[0007] S3. Impregnation and carbonization: Immerse the activated bamboo fibers in the carbonizing agent, heat to 50-60℃, and stir for 2-4 hours to complete the carbonization process;

[0008] S4. Crosslinking and curing: After the carbonization process is completed, the bamboo fibers are taken out of the carbonizing agent and drained. They are washed three times with deionized water and then immersed in deionized water containing 3% sodium hydroxide. The temperature is raised to 90-100℃ and stirred for 1-3 hours to complete the crosslinking and curing.

[0009] S5. Drying and Hot Pressing: The cross-linked and cured bamboo fibers are filtered and separated from deionized water containing 3% sodium hydroxide. After washing with deionized water, the fibers are dried in a forced-air drying oven at 75-85℃ for 1-3 hours. After the dried bamboo fibers are laid out, they are hot-pressed in a hot press at 130-150℃ and 1.5-2.5MPa pressure for 40-70 minutes. After cooling to room temperature, the reconstituted bamboo board is produced.

[0010] Preferably, in S2, the functionalized ionic liquid, deionized water, bis(3-formylphenyl) peroxide dicarbonate, poly(glycidyl methacrylate-co-styrene) and N-methylpyrrolidone are in a weight ratio of 30-40:30-40:5-7:3-5:10-20.

[0011] Preferably, the specific preparation method of the functionalized ionic liquid in S2 is as follows:

[0012] (1) Add N-methylimidazolium to acetonitrile, heat to 50-70℃ with stirring, add 3-bromopropionic acid dropwise over 1-2 hours. After the addition is complete, heat to 80-90℃ and react for 3-5 hours. Concentrate under reduced pressure to remove the solvent. Recrystallize the remaining product in ethanol to obtain 1-carboxyethyl-3-methylimidazolium bromide. The chemical reaction equation is as follows:

[0013] The product was characterized by ¹H NMR. In the N-methylimidazolium molecule, the nitrogen atom on the imidazolium ring acts as a nucleophilic center, attacking the partially positively charged brominated carbon in the 3-bromopropionic acid molecule. The bromide ion departs as a leaving group, forming a 1-carboxyethyl-3-methylimidazolium cation, which then reacts with Br₂. - They combine to form bromide salts;

[0014] (2) Add 1-carboxyethyl-3-methylimidazolium bromide to methanol, stir for 10-20 min, then add sodium p-hydroxybenzoate, heat to 60-70℃, react for 2-4 h, cool to room temperature, filter, concentrate the filtrate under reduced pressure to remove solvent, dissolve the product in deionized water, purify by 732 type cation exchange resin column, collect the effluent and dry to obtain functionalized ionic liquid. The chemical reaction equation is as follows:

[0015] The product was characterized by 1H NMR, showing that 1-carboxyethyl-3-methylimidazolium bromide dissociates in methanol into cations (1-carboxyethyl-3-methylimidazolium) and Br. - Sodium p-hydroxybenzoate dissociates into Na + And p-hydroxybenzoate, due to the affinity of p-hydroxybenzoate for imidazolium cations, through hydrogen bonding and electrostatic interactions, is stronger than Br. - Anion exchange occurs, forming the target ionic liquid, and the generated NaBr can be removed by filtration.

[0016] Preferably, in (1), the molar ratio of N-methylimidazole to 3-bromopropionic acid is 1:1-1.4. Preferably, in (1), the weight ratio of N-methylimidazole to acetonitrile is 1:8-12.

[0017] Preferably, in (2), the molar ratio of 1-carboxyethyl-3-methylimidazolium bromide and sodium p-hydroxybenzoate is 1:1-1.2.

[0018] Preferably, in (2), the weight ratio of 1-carboxyethyl-3-methylimidazolium bromide and methanol is 1:8-12.

[0019] Preferably, the specific preparation method of bis(3-formylphenyl) peroxide dicarbonate in S2 is as follows:

[0020] (a) In the reaction vessel of the tail gas absorption device, 3-formylbenzoic acid, anhydrous DMF and anhydrous toluene are added, stirred and cooled to below 0°C, and oxalyl chloride is added dropwise over 1-2 hours, with the temperature controlled not to exceed 5°C during the addition. After the addition is complete, the mixture is brought back to room temperature and reacted for 2-4 hours. The solvent is removed by concentration under reduced pressure. The remaining product is recrystallized in a mixed solution of anhydrous toluene / anhydrous n-hexane to obtain the acyl chloride intermediate. The chemical reaction equation is as follows:

[0021] The product was characterized by H NMR. Oxaloyl chloride, as a strong acylation reagent, attacked the hydroxyl oxygen of carboxylic acid under anhydrous DMF catalysis (DMF and oxaloyl chloride first form an active intermediate). After forming a transition state, the chlorine atom replaced the hydroxyl group (-OH→-Cl) to generate an acyl chloride intermediate, while releasing CO2 and CO.

[0022] (b) Add the acyl chloride intermediate and triethylamine to anhydrous dichloromethane, stir and cool to below 0°C, then add a 30% hydrogen peroxide solution dropwise over 1-2 hours, controlling the temperature to not exceed 5°C during the addition. After the addition is complete, continue the reaction for 1-2 hours, then add deionized water to quench the reaction. Collect the organic phase by separation, wash the organic phase with saturated sodium bicarbonate and deionized water respectively, dry it with anhydrous sodium sulfate, and concentrate it under reduced pressure to remove the solvent. The crude product is recrystallized in a mixed solution of ethyl acetate / petroleum ether to obtain bis(3-formylphenyl) peroxide dicarbonate. The chemical reaction equation is as follows:

[0023] The product was characterized by 1H NMR, showing that hydrogen peroxide dissociates into peroxide anions (HOO) in the presence of triethylamine. - As a nucleophile, it attacks the carbonyl carbon of the acyl chloride, and the chlorine atom is released as a leaving group to form a peroxy ester bond (-OO-CO-). At the same time, HCl is generated and neutralized by triethylamine. The two molecules of acyl chloride intermediate react with one molecule of hydrogen peroxide to finally form bis(3-formylphenyl) peroxydicarbonate.

[0024] Preferably, in (a), the molar ratio of 3-formylbenzoic acid and oxaloyl chloride is 1:0.5-0.7.

[0025] Preferably, in (a), 3-formylbenzoic acid, anhydrous DMF and anhydrous toluene are in a weight ratio of 1:0.02-0.06:8-12.

[0026] Preferably, the anhydrous toluene / anhydrous n-hexane mixed solution in (a) refers to anhydrous toluene and anhydrous n-hexane mixed in a weight ratio of 3:1.

[0027] Preferably, in step (b), the molar ratio of the acyl chloride intermediate to the hydrogen peroxide in the 30% hydrogen peroxide solution is 1:1-1.2.

[0028] Preferably, in (b), the acyl chloride intermediate, triethylamine, and anhydrous dichloromethane are in a weight ratio of 1:0.02-0.06:8-12.

[0029] Preferably, the ethyl acetate / petroleum ether mixed solution in (b) refers to a mixture of ethyl acetate and petroleum ether in a weight ratio of 1:3.

[0030] Preferably, the specific preparation method of poly(glycidyl methacrylate-co-styrene) in S2 is as follows:

[0031] Under nitrogen protection, glycidyl methacrylate, styrene, azobisisobutyronitrile, benzyl dithiobenzoate, and tetrahydrofuran were added to a reaction vessel and stirred for 20-40 min. The mixture was then heated to 65-75 °C and reacted for 5-7 h. After the reaction was complete, the reaction solution was poured into methanol to precipitate the poly(glycidyl methacrylate-co-styrene). The precipitate was collected, washed, and dried to obtain poly(glycidyl methacrylate-co-styrene). A schematic diagram of the chemical reaction is shown below.

[0032] The product was characterized by F-TIR infrared spectroscopy. Glycidyl methacrylate (GMA) and styrene (St) underwent reversible addition-fragmentation chain transfer copolymerization. During the initiation stage, azobisisobutyronitrile (AIBN) decomposed to generate primary free radicals, which initiated the polymerization of GMA and St monomers to form active chain free radicals. Benzyl dithiobenzoate (RAFT reagent) underwent reversible addition with the active chain free radicals to form intermediate free radicals, which then cleaved into new RAFT reagents and new active chain free radicals. The chain growth rate was controlled through the "addition-fragmentation" equilibrium to achieve molecular weight uniformity.

[0033] Preferably, in the specific preparation method of the poly(glycidyl methacrylate-co-styrene), the molar ratio of glycidyl methacrylate, styrene, and poly(glycidyl methacrylate-co-styrene) is 3:1-2.

[0034] Preferably, in the specific preparation method of the poly(glycidyl methacrylate-co-styrene), the weight ratio of glycidyl methacrylate, azobisisobutyronitrile, benzyl dithiobenzoate and tetrahydrofuran is 1:0.005-0.015:0.003-0.007:8-12.

[0035] Preferably, the carbonization mechanism in S2 is as follows: The functionalized ionic liquid, due to the presence of polar groups such as imidazole rings, carboxyethyl groups, and p-hydroxybenzoate groups in its molecules, forms multiple hydrogen bonds with the hydroxyl groups of bamboo cellulose. Simultaneously, the electrostatic interaction between its cations and the cellulose chains disrupts the crystalline structure of cellulose, increasing the spacing between the originally tightly packed cellulose molecular chains. This swelling effect increases the porosity of the bamboo fibers. The core benefit of this swelling is that it provides a penetration channel for peroxides, copolymers, and other components in the subsequent carbonizing agent, allowing them to penetrate deep into the bamboo fibers rather than remaining only on the surface, laying the foundation for uniform degradation and cross-linking. Subsequently, starch and protein degrade. During the impregnation and carbonization stage at 50-60°C, bis(3-formylphenyl) peroxide dicarbonate undergoes homolytic cleavage of peroxy bonds under the catalysis of the functionalized ionic liquid. This catalytic effect originates from the carboxyl groups in the anionic and cationic side chains of the functionalized ionic liquid. As strong proton donors, the carboxyl groups can transfer protons to the oxygen atoms in the peroxy bonds, forming an unstable protonated intermediate (-O). +The addition of HO- shifts the electron cloud density of the peroxide bond towards the protonated oxygen atom, reducing the bond energy and significantly weakening the bond stability. Simultaneously, the hydrogen bond formed between the carboxyl group and the peroxide bond further lowers the activation energy for homolytic cleavage, promoting the homolytic cleavage of the peroxide bond. The reaction can be represented as follows:

[0036] The generated free radicals possess strong oxidizing properties. In the case of starch in bamboo fibers, the basic molecular unit is glucose linked by α-1,4 glycosidic bonds or α-1,4 and α-1,6 glycosidic bonds. In the α-glycosidic bond, the C1 hydroxyl group of the glucose unit is on the same side as the C4 hydroxyl group of the adjacent unit, forming a "cis" conformation. This structure results in a high electron cloud density of the oxygen atom in the glycosidic bond, a large bond angle, and low steric hindrance, making it susceptible to attack by free radicals generated by peroxides. These free radicals can directly approach the oxygen atom of the glycosidic bond, steal electrons, and initiate homolytic cleavage. The resulting small molecular fragments are further oxidized to CO2 and H2O. Simultaneously, starch has extremely low crystallinity; amylose, due to its high molecular chain flexibility, only forms locally ordered molecules. The microcrystalline region is mostly amorphous. Amylopectin, due to its numerous branches, has almost no crystalline regions. This loose amorphous structure fully exposes the starch molecular chains, allowing free radicals in the carbonizing agent to easily penetrate and contact them, greatly improving degradation efficiency. For proteins, the amino groups in their molecules act as nucleophilic sites, undergoing electron transfer reactions with free radicals. After the amino group is oxidized to an imino group, the peptide bond breaks due to the decrease in electron cloud density. The resulting small amino acids (such as glycine and alanine) contain polar groups and can dissolve in the carbonizing agent containing ionic liquids and water, ultimately removing starch and protein. The dissolution and degradation of hemicellulose in bamboo fibers depends on the synergistic effect of ionic liquids and N-methylpyrrolidone. Hemicellulose is composed of wood fibers... Heteropolysaccharides composed of polysaccharides, mannans, etc., contain a large number of hydroxyl and acetyl groups in their molecules. The cations of the ionic liquid adsorb hemicellulose chains through electrostatic interactions, breaking the hydrogen bonds between hemicellulose and cellulose. At the same time, N-methylpyrrolidone, as a polar aprotic solvent, forms hydrogen bonds with the hydroxyl groups of hemicellulose, assisting in its detachment from the bamboo fiber structure. The detached hemicellulose undergoes partial cleavage of glycosidic bonds by free radicals, similar to the mechanism of starch, but with slightly lower reactivity, forming oligosaccharides. The solubility of these oligosaccharides is significantly enhanced in the mixed system of ionic liquid and N-methylpyrrolidone, thus achieving dissolution and removal. The degradation and dissolution of lignin mainly relies on the synergistic effect of poly(glycidyl methacrylate-co-styrene) and N-methylpyrrolidone. Simultaneously, lignin possesses a three-dimensional structure with phenylpropane units linked by ether bonds and carbon-carbon bonds. Its benzene ring structure exhibits π-π stacking interactions with the styrene segments in poly(glycidyl methacrylate-co-styrene), while the epoxy groups in the poly(glycidyl methacrylate-co-styrene) segments form hydrogen bonds with the phenolic hydroxyl groups of lignin. This dual interaction facilitates the exfoliation of lignin from bamboo fibers. At the same time, the amide bonds of N-methylpyrrolidone interact with the ether bonds of lignin, reducing intermolecular forces and promoting the dissolution of the exfoliated lignin. Furthermore, the free radicals generated by the decomposition of peroxides attack the ether bonds of lignin, causing some of them to break into smaller molecular fragments, further improving the dissolution efficiency and achieving highly efficient removal.

[0037] Preferably, the cross-linking and curing mechanism in S3 is as follows: After carbonization, the starch and protein in the bamboo fibers are efficiently degraded into small molecule products (such as oligosaccharides and amino acids) by the free radicals generated by peroxides. These products have extremely weak interactions with the cellulose in the bamboo fibers. The hydroxyl groups of oligosaccharides only form weak hydrogen bonds with the hydroxyl groups of cellulose, and the polar interaction between the amino groups of amino acids and cellulose is unstable due to their small molecular size and high fluidity. At the same time, these small molecules have high water solubility and can quickly diffuse to the surface of the bamboo fibers through the pores after swelling. Therefore, during washing, the water flow only needs to pass through surface rinsing and shallow penetration to remove these free small molecule degradation products, avoiding them from competing with the hydroxyl groups of cellulose for reaction sites during the cross-linking stage. Hemicellulose and lignin are also largely dissolved and removed under the synergistic effect of functionalized ionic liquids, copolymers, and N-methylpyrrolidone. Conversely, the peroxide derivatives (containing aldehyde groups) and poly(glycidyl methacrylate-co-styrene) (containing epoxy groups) inside the bamboo fibers can be stably retained, mainly due to their strong interaction with cellulose and the physical retention of the bamboo fiber structure.

[0038] The aldehyde group (-CHO) of the peroxide derivative forms stable hydrogen bonds with the hydroxyl groups of cellulose. Its benzene ring structure interacts with the aromatic region of cellulose via π-π stacking, a dual effect that firmly adsorbs it onto the cellulose molecular chain. The epoxy group (three-membered ring) of the polymer binds tightly to the cellulose hydroxyl groups through polar interactions, and the styrene segments form van der Waals forces with the hydrophobic regions of cellulose, making the polymer chains interwoven within the cellulose network and difficult to detach. Ultimately, the bamboo fibers primarily retain structurally intact cellulose. This is because during carbonization, the glucose units of cellulose are connected via β-1,4 glycosidic bonds, with the C1 hydroxyl group on the opposite side of the C4 hydroxyl group of the adjacent unit, forming a "trans" conformation. The oxygen atom electron cloud density of the glycosidic bond is low, and the bond angle is small, leaving little empty space. The cellulose exhibits significant steric hindrance. Furthermore, the linear extension of cellulose molecular chains, with adjacent chains forming a stable "lamellar structure" through dense intermolecular hydrogen bonds, further hinders free radical attack on glycosidic bonds. Free radicals must break through the hydrogen bond network to contact glycosidic bonds, increasing the activation energy and making degradation more difficult. Additionally, cellulose possesses high crystallinity, with molecular chains arranged in an orderly fashion through hydrogen bonds to form crystalline regions. Only a small number of amorphous regions exist at the edges of these crystalline regions. The tightly packed molecular chains in the crystalline regions make it difficult for solvents and free radicals to penetrate. Only the cellulose hydroxyl groups in the amorphous regions can contact free radicals, but their proportion is low, and the reaction efficiency is low due to the spatial limitations of the crystalline regions. Therefore, the molecular chain structure of cellulose is completely preserved, and preserving cellulose is the core basis for subsequent cross-linking and curing. As the main structural component of bamboo fiber, cellulose has abundant hydroxyl groups on its molecular chain that can serve as reaction sites to participate in cross-linking reactions. It constructs a three-dimensional network structure by forming covalent bonds. During the cross-linking and curing stage at 90-100℃, based on the retained cellulose, cross-linking and curing are mainly achieved through two chemical reactions: The first is the condensation reaction between aldehyde groups and cellulose hydroxyl groups. The breaking of the peroxide bond in bis(3-formylphenyl) peroxide dicarbonate not only generates free radicals but also produces aldehyde-containing products (3-formylphenyl carbonate derivatives). These aldehyde groups undergo a condensation reaction with the hydroxyl groups on the cellulose molecular chain under alkaline conditions at 90-100℃, blocking some of the hydroxyl groups and reducing its hydrophilicity. Simultaneously, the carbonate groups in its molecule can bind to another cellulose molecule through hydrogen bonds. The first type involves the formation of -OH…O-CO- bonds or van der Waals forces between the hydroxyl groups of the cellulose chain and adjacent cellulose chains. In this case, although a single derivative molecule is only connected to a cellulose chain through an aldehyde group, its other end is "anchored" to another cellulose chain through weak interactions, thus achieving cross-linking. The second type is the ring-opening addition reaction between the epoxy groups in poly(glycidyl methacrylate-co-styrene) and the hydroxyl groups of cellulose. In an alkaline environment at 90-100℃, the epoxy groups on the copolymer molecular chain are attacked by the hydroxyl groups of cellulose, resulting in a ring-opening reaction. This reaction causes the copolymer molecular chains to interweave between the cellulose molecular chains, connecting the cellulose into a tighter three-dimensional network through covalent bonds, further sealing the hydroxyl groups, reducing the water absorption and swelling rate of bamboo fibers, and improving the bonding strength between bamboo fibers.

[0039] The beneficial effects of this invention are:

[0040] 1. This invention utilizes the unique structure of functionalized ionic liquids to form multiple hydrogen bonds and electrostatic interactions with bamboo cellulose, increasing the porosity of bamboo fibers and providing channels for the deep penetration of bis(3-formylphenyl) peroxide dicarbonate derivatives and poly(glycidyl methacrylate-co-styrene). Specifically, the aldehyde groups of the peroxide derivative undergo a condensation reaction with the cellulose hydroxyl groups, sealing the hydroxyl groups; the epoxy groups of the copolymer undergo a ring-opening addition reaction with the cellulose hydroxyl groups under alkaline conditions, completing cross-linking. These two reactions not only construct a three-dimensional cross-linked network within the bamboo fibers but also occur at the interfaces of adjacent bamboo fibers, "welding" the bamboo fibers into a whole through covalent bonds. This chemical bonding strength is far superior to the physical adsorption between resin and fiber in traditional impregnation processes, achieving excellent static bending strength and internal bonding strength without the need for additional adhesives. Simultaneously, it avoids environmental problems such as formaldehyde release associated with adhesives, reducing production costs.

[0041] 2. In the carbonization process of this invention, the free radicals generated by bis(3-formylphenyl) peroxide dicarbonate under the catalysis of a functionalized ionic liquid degrade impurities such as starch and protein, and simultaneously undergo a selective oxidation reaction with lignin in bamboo fibers. After the phenylpropane units in the lignin are oxidized, their phenolic hydroxyl groups are converted into chromophores such as quinone groups, and intermolecular condensation occurs, forming a dark brown to light brown hue similar to that of physical carbonization. The synergistic effect of the functionalized ionic liquid and N-methylpyrrolidone ensures the uniformity of the reaction, resulting in consistent color across all parts of the bamboo fibers, avoiding the color differences caused by uneven temperature distribution in traditional physical carbonization. Furthermore, after moderate oxidation of lignin, the surface roughness of the bamboo fibers decreases, and combined with the dense structure formed after cross-linking and curing, it gives the bamboo board a warm and delicate texture, superior to the dry feel of traditional physical carbonization. This color change originates from the chemical transformation of the bamboo fibers themselves, requiring no additional colorants.

[0042] 3. Among the core components of the carbonizing agent used in this invention, the functionalized ionic liquid and N-methylpyrrolidone are chemically stable and do not easily decompose at a carbonization temperature of 50-60℃. Only bis(3-formylphenyl) peroxide dicarbonate (due to the breakage of peroxide bonds) and poly(glycidyl methacrylate-co-styrene) (due to penetration into the bamboo fibers) are gradually consumed with use. The reacted carbonizing agent can be separated from the bamboo fibers by filtration. After detecting the remaining content of each component using high-performance liquid chromatography, only the consumed peroxide and copolymer need to be added to restore the activity of the carbonizing agent, allowing it to be reused in the impregnation and carbonization process. This recycling mechanism significantly reduces reagent consumption, and the entire process does not require waste liquid discharge, reducing environmental pollution and meeting the requirements of green production, while also reducing the raw material costs for industrial production.

[0043] 4. The deep swelling effect of the functionalized ionic liquid in this invention allows the peroxide derivative and copolymer to fully contact the cellulose molecular chains, covalently blocking a large number of hydroxyl groups and significantly reducing the hydrophilicity of bamboo fibers. Simultaneously, components easily utilized by mold, such as starch and protein, are completely degraded into small molecules and removed with water, cutting off the mold's nutrient source. This dual effect of "hydroxyl group blocking + impurity removal" effectively inhibits the water absorption and swelling of the bamboo board, improving its dimensional stability in humid environments. Furthermore, due to the absence of nutrient residue, the antibacterial and anti-corrosion properties of the bamboo board are greatly enhanced, extending its service life. Attached Figure Description

[0044] Figure 1 This is a flowchart of the integrated carbonization and wire drawing process for reconstituted bamboo boards proposed in this invention;

[0045] Figure 2 The 1H NMR spectrum of 1-carboxyethyl-3-methylimidazolium bromide prepared in Example 2 of this invention;

[0046] Figure 3 The H NMR spectrum of the functionalized ionic liquid prepared in Example 2 of this invention;

[0047] Figure 4 The 1H NMR spectrum of the acyl chloride intermediate prepared in Example 5 of this invention;

[0048] Figure 5 FTIR infrared spectrum of poly(glycidyl methacrylate-co-styrene) prepared in Example 8 of this invention;

[0049] Figure 6 This is a physical image of the reconstituted bamboo board prepared in Example 2 of the present invention. Detailed Implementation

[0050] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0051] Preparation Examples 1-3: Specific preparation methods for functionalized ionic liquids:

[0052] Preparation Example 1: (1) 100g of N-methylimidazolium was added to 800g of acetonitrile, and the temperature was raised to 50°C with stirring. 186.32g of 3-bromopropionic acid was added dropwise over a period of 1 hour. After the addition was completed, the temperature was raised to 80°C and the reaction was carried out for 3 hours. The solvent was removed by concentration under reduced pressure. The remaining product was recrystallized in ethanol to obtain 1-carboxyethyl-3-methylimidazolium bromide.

[0053] (2) Add 250g of 1-carboxyethyl-3-methylimidazolium bromide to 2kg of methanol, stir for 10min, then add 170.26g of sodium p-hydroxybenzoate, heat to 60℃, react for 2h, cool to room temperature, filter, concentrate the filtrate under reduced pressure to remove solvent, dissolve the product in deionized water, purify by 732 cation exchange resin column, collect the effluent and dry to obtain functionalized ionic liquid.

[0054] Preparation Example 2: (1) 100g of N-methylimidazolium was added to 1kg of acetonitrile, and the temperature was raised to 60°C with stirring. 233.59g of 3-bromopropionic acid was added dropwise over a period of 1.5h. After the addition was completed, the temperature was raised to 85°C and the reaction was carried out for 4h. The solvent was removed by concentration under reduced pressure. The remaining product was recrystallized in ethanol to obtain 1-carboxyethyl-3-methylimidazolium bromide.

[0055] (2) Add 250g of 1-carboxyethyl-3-methylimidazolium bromide to 2.5kg of methanol, stir for 15min, then add 187.29g of sodium p-hydroxybenzoate, heat to 65℃, react for 3h, cool to room temperature, filter, concentrate the filtrate under reduced pressure to remove solvent, dissolve the product in deionized water, purify by 732 type cation exchange resin column, collect the effluent and dry to obtain functionalized ionic liquid.

[0056] Preparation Example 3: (1) 100g of N-methylimidazolium was added to 1.2kg of acetonitrile, and the temperature was raised to 70°C with stirring. 260.85g of 3-bromopropionic acid was added dropwise over a period of 2 hours. After the addition was completed, the temperature was raised to 90°C and the reaction was carried out for 5 hours. The solvent was removed by concentration under reduced pressure. The remaining product was recrystallized in ethanol to obtain 1-carboxyethyl-3-methylimidazolium bromide.

[0057] (2) Add 250g of 1-carboxyethyl-3-methylimidazolium bromide to 3kg of methanol, stir for 20min, then add 204.31g of sodium p-hydroxybenzoate, heat to 70℃, react for 4h, cool to room temperature, filter, concentrate the filtrate under reduced pressure to remove solvent, dissolve the product in deionized water, purify by 732 type cation exchange resin column, collect the effluent and dry to obtain functionalized ionic liquid.

[0058] Preparation Examples 4-6: Specific preparation method of bis(3-formylphenyl) peroxide dicarbonate:

[0059] Preparation Example 4: (a) In the reaction vessel of the tail gas absorption device, 10 g of 3-formylbenzoic acid, 0.2 g of anhydrous DMF and 80 g of anhydrous toluene were added, stirred and cooled to below 0 °C, and 4.23 g of oxalyl chloride was added dropwise over 1 h. During the dropwise addition, the temperature was controlled not to exceed 5 °C. After the dropwise addition was completed, the temperature was restored to room temperature and the reaction was carried out for 2 h. The solvent was removed by concentration under reduced pressure. The remaining product was recrystallized in an anhydrous toluene / anhydrous n-hexane mixed solution (anhydrous toluene and anhydrous n-hexane were mixed in a weight ratio of 3:1) to obtain the acyl chloride intermediate.

[0060] (b) 10 g of acyl chloride intermediate and 0.2 g of triethylamine were added to 80 g of anhydrous dichloromethane. The mixture was stirred and cooled to below 0 °C. 6.72 g of 30% hydrogen peroxide solution was added dropwise over 1 h. The temperature was controlled to not exceed 5 °C during the addition process. After the addition was completed, the reaction was continued for 1 h. The reaction was quenched with deionized water. The organic phase was collected by separation. The organic phase was washed with saturated sodium bicarbonate and deionized water, and then dried with anhydrous sodium sulfate. The solvent was removed by concentration under reduced pressure. The crude product was recrystallized in a mixed solution of ethyl acetate and petroleum ether (ethyl acetate and petroleum ether were mixed in a weight ratio of 1:3) to obtain bis(3-formylphenyl) peroxide dicarbonate.

[0061] Preparation Example 5: (a) In the reaction vessel of the tail gas absorption device, 10 g of 3-formylbenzoic acid, 0.4 g of anhydrous DMF and 100 g of anhydrous toluene were added, stirred and cooled to below 0 °C, and 5.07 g of oxalyl chloride was added dropwise over a period of 1.5 h. During the addition, the temperature was controlled not to exceed 5 °C. After the addition was completed, the temperature was restored to room temperature and the reaction was allowed to proceed for 3 h. The solvent was removed by concentration under reduced pressure. The remaining product was recrystallized in a mixed solution of anhydrous toluene and anhydrous n-hexane (prepared by mixing anhydrous toluene and anhydrous n-hexane in a weight ratio of 3:1) to obtain the acyl chloride intermediate.

[0062] (b) 10 g of acyl chloride intermediate and 0.4 g of triethylamine were added to 100 g of anhydrous dichloromethane. The mixture was stirred and cooled to below 0 °C. 7.40 g of 30% hydrogen peroxide solution was added dropwise over 1.5 h. The temperature was controlled to not exceed 5 °C during the addition process. After the addition was completed, the reaction was continued for 1.5 h. The reaction was quenched with deionized water. The organic phase was collected by separation and washed with saturated sodium bicarbonate and deionized water, respectively. The organic phase was then dried with anhydrous sodium sulfate and concentrated under reduced pressure to remove the solvent. The crude product was recrystallized in a mixed solution of ethyl acetate and petroleum ether (ethyl acetate and petroleum ether were mixed in a weight ratio of 1:3) to obtain bis(3-formylphenyl) peroxide dicarbonate.

[0063] Preparation Example 6: (a) In the reaction vessel of the tail gas absorption device, 10 g of 3-formylbenzoic acid, 0.6 g of anhydrous DMF and 120 g of anhydrous toluene were added, stirred and cooled to below 0 °C, and 5.92 g of oxalyl chloride was added dropwise over 2 h. During the dropwise addition, the temperature was controlled not to exceed 5 °C. After the dropwise addition was completed, the temperature was restored to room temperature and the reaction was carried out for 4 h. The solvent was removed by concentration under reduced pressure. The remaining product was recrystallized in an anhydrous toluene / anhydrous n-hexane mixed solution (anhydrous toluene and anhydrous n-hexane were mixed in a weight ratio of 3:1) to obtain the acyl chloride intermediate.

[0064] (b) 10 g of acyl chloride intermediate and 0.6 g of triethylamine were added to 120 g of anhydrous dichloromethane. The mixture was stirred and cooled to below 0 °C. 8.07 g of 30% hydrogen peroxide solution was added dropwise over 2 h. The temperature was controlled to not exceed 5 °C during the addition process. After the addition was completed, the reaction was continued for 2 h. The reaction was quenched with deionized water. The organic phase was collected by separation. The organic phase was washed with saturated sodium bicarbonate and deionized water, and then dried with anhydrous sodium sulfate. The solvent was removed by concentration under reduced pressure. The crude product was recrystallized in a mixed solution of ethyl acetate and petroleum ether (ethyl acetate and petroleum ether were mixed in a weight ratio of 1:3) to obtain bis(3-formylphenyl) peroxide dicarbonate.

[0065] Preparation Examples 7-9: Specific preparation method of poly(glycidyl methacrylate-co-styrene):

[0066] Preparation Example 7: Under nitrogen protection, 10g glycidyl methacrylate, 2.44g styrene, 0.05g azobisisobutyronitrile, 0.03g benzyl dithiobenzoate and 80g tetrahydrofuran were added to a reaction vessel and stirred for 20min. Then the temperature was raised to 65℃ and the reaction was carried out for 5h. After the reaction was completed, the reaction solution was poured into methanol to precipitate. The precipitate was collected, washed, and dried to obtain poly(glycidyl methacrylate-co-styrene).

[0067] Preparation Example 8: Under nitrogen protection, 10g glycidyl methacrylate, 3.66g styrene, 0.1g azobisisobutyronitrile, 0.05g benzyl dithiobenzoate and 100g tetrahydrofuran were added to a reaction vessel and stirred for 30min. Then the temperature was raised to 70℃ and the reaction was carried out for 6h. After the reaction was completed, the reaction solution was poured into methanol to precipitate. The precipitate was collected, washed, and dried to obtain poly(glycidyl methacrylate-co-styrene).

[0068] Preparation Example 9: Under nitrogen protection, 10 g glycidyl methacrylate, 4.88 g styrene, 0.15 g azobisisobutyronitrile, 0.07 g benzyl dithiobenzoate and tetrahydrofuran were added to a reaction vessel and stirred for 40 min. Then the temperature was raised to 75 °C and the reaction was carried out for 7 h. After the reaction was completed, the reaction solution was poured into methanol to precipitate, the precipitate was collected, washed, and dried to obtain poly(glycidyl methacrylate-co-styrene).

[0069] Comparative Preparation Example 1: The difference between Comparative Preparation Example 1 and Preparation Example 2 is that 3-bromopropionic acid is replaced with bromobutane.

[0070] Comparative Preparation Example 2: The difference between Comparative Preparation Example 2 and Preparation Example 2 is that step (2) is omitted. The 1-carboxyethyl-3-methylimidazolium bromide obtained in step (1) is the functionalized ionic liquid.

[0071] Comparative Preparation Example 3: The difference between Comparative Preparation Example 3 and Preparation Example 5 is that benzoyl peroxide was directly used to replace the bis(3-formylphenyl) peroxide dicarbonate prepared in Preparation Example 5.

[0072] Comparative Preparation Example 4: The difference between Comparative Preparation Example 4 and Preparation Example 8 is that poly(glycidyl methacrylate-co-styrene) prepared in Preparation Example 8 was directly replaced with poly(glycidyl methacrylate-co-styrene).

[0073] Comparative Preparation Example 5: The difference between Comparative Preparation Example 5 and Preparation Example 8 is that polystyrene was directly used to replace the poly(glycidyl methacrylate-co-styrene) prepared in Preparation Example 8.

[0074] Example 1: An integrated carbonization and wire drawing process for reconstituted bamboo boards, comprising the following steps:

[0075] S1. Bamboo Fiber Activation: Select 3-5 year old moso bamboo, remove the nodes and outer skin, cut the bamboo into 200mm long sections, and use a double roller bamboo fiber drawing machine at a speed of 200r / min to draw the bamboo sections into bamboo fibers with a thickness of 0.5mm and a width of 2mm. During the bamboo fiber drawing process, spray deionized water at a flow rate of 5mL / min to prevent the bamboo fibers from overheating. Place the bamboo fibers into an ultrasonic cleaning tank (power 300W, frequency 10kHz), immerse the bamboo fibers in deionized water, and ultrasonically treat for 5 minutes. Remove and drain to obtain activated bamboo fibers.

[0076] S2. Preparation of carbonizing agent: Add 3 kg of the functionalized ionic liquid prepared according to Preparation Example 1 to 3 kg of deionized water, stir for 30 min, then add 500 g of bis(3-formylphenyl) peroxide dicarbonate prepared according to Preparation Example 4, 300 g of poly(glycidyl methacrylate-co-styrene) prepared according to Preparation Example 7 and 1 kg of N-methylpyrrolidone in sequence, and continue stirring for 1 h to obtain the carbonizing agent;

[0077] S3. Impregnation and carbonization: Immerse the activated bamboo fibers in the carbonizing agent, heat to 50°C, and stir for 2 hours to complete the carbonization process.

[0078] S4. Crosslinking and curing: After the carbonization process is completed, the bamboo fibers are taken out of the carbonizing agent and drained. They are washed three times with deionized water and then immersed in deionized water containing 3% sodium hydroxide. The temperature is raised to 90°C and stirred for 1 hour to complete the crosslinking and curing.

[0079] S5. Drying and Hot Pressing: The cross-linked and cured bamboo fibers are filtered and separated from deionized water containing 3% sodium hydroxide. After washing with deionized water, the bamboo fibers are dried in a forced-air drying oven at 75°C for 1 hour. After the dried bamboo fibers are laid out, they are hot-pressed in a hot press at 130°C and 1.5MPa for 40 minutes. After cooling to room temperature, the reconstituted bamboo board is made.

[0080] Example 2: An integrated carbonization and wire drawing process for reconstituted bamboo boards, comprising the following steps:

[0081] S1. Bamboo Fiber Activation: Select 3-5 year old moso bamboo, remove the nodes and outer skin, cut the bamboo into 250mm long sections, and use a double roller bamboo fiber drawing machine at a speed of 250r / min to draw the bamboo sections into bamboo fibers with a thickness of 0.75mm and a width of 2.5mm. During the bamboo fiber drawing process, spray deionized water at a flow rate of 7mL / min to prevent the bamboo fibers from overheating. Place the bamboo fibers into an ultrasonic cleaning tank (power 500W, frequency 15kHz), immerse the bamboo fibers in deionized water, and ultrasonically treat for 10 minutes. Remove and drain to obtain activated bamboo fibers.

[0082] S2. Preparation of carbonizing agent: Add 3.5 kg of the functionalized ionic liquid prepared according to Preparation Example 2 to 3.5 kg of deionized water and stir for 35 min. Then add 600 g of bis(3-formylphenyl) peroxide dicarbonate prepared according to Preparation Example 5, 400 g of poly(glycidyl methacrylate-co-styrene) prepared according to Preparation Example 8 and 1.5 kg of N-methylpyrrolidone in sequence, and continue stirring for 1.5 h to obtain the carbonizing agent.

[0083] S3. Impregnation and carbonization: Immerse the activated bamboo fibers in the carbonizing agent, heat to 55°C, and react for 3 hours with stirring to complete the carbonization process.

[0084] S4. Crosslinking and curing: After the carbonization process is completed, the bamboo fibers are taken out of the carbonizing agent and drained. They are washed three times with deionized water and then immersed in deionized water containing 3% sodium hydroxide. The temperature is raised to 95°C and stirred for 2 hours to complete the crosslinking and curing.

[0085] S5. Drying and Hot Pressing: The cross-linked and cured bamboo fibers are filtered and separated from deionized water containing 3% sodium hydroxide. After washing with deionized water, the bamboo fibers are dried in a forced-air drying oven at 80°C for 2 hours. After the dried bamboo fibers are laid out, they are hot-pressed in a hot press at 140°C and 2MPa for 55 minutes. After cooling to room temperature, the reconstituted bamboo board is produced.

[0086] Example 3: An integrated carbonization and wire drawing process for reconstituted bamboo boards, comprising the following steps:

[0087] S1. Bamboo Fiber Activation: Select 3-5 year old moso bamboo, remove the nodes and outer skin, cut the bamboo into 300mm long sections, and use a double roller bamboo fiber drawing machine at a speed of 300r / min to draw the bamboo sections into bamboo fibers with a thickness of 1mm and a width of 3mm. During the bamboo fiber drawing process, spray deionized water at a flow rate of 10mL / min to prevent the bamboo fibers from overheating. Place the bamboo fibers into an ultrasonic cleaning tank (power 700W, frequency 20kHz), immerse the bamboo fibers in deionized water, and ultrasonically treat for 15min. Remove and drain to obtain activated bamboo fibers.

[0088] S2. Preparation of carbonizing agent: Add 4 kg of the functionalized ionic liquid prepared according to Preparation Example 3 to 4 kg of deionized water and stir for 40 min. Then add 700 g of bis(3-formylphenyl) peroxide dicarbonate prepared according to Preparation Example 6, 500 g of poly(glycidyl methacrylate-co-styrene) prepared according to Preparation Example 9 and 2 kg of N-methylpyrrolidone in sequence, and continue stirring for 2 h to obtain the carbonizing agent.

[0089] S3. Impregnation and carbonization: Immerse the activated bamboo fibers in the carbonizing agent, heat to 60°C, and react for 4 hours with stirring to complete the carbonization process;

[0090] S4. Crosslinking and curing: After the carbonization process is completed, the bamboo fibers are taken out of the carbonizing agent and drained. They are washed three times with deionized water and then immersed in deionized water containing 3% sodium hydroxide. The temperature is raised to 100°C and stirred for 3 hours to complete the crosslinking and curing.

[0091] S5. Drying and Hot Pressing: The cross-linked and cured bamboo fibers are filtered and separated from deionized water containing 3% sodium hydroxide. After washing with deionized water, the fibers are dried in a forced-air drying oven at 85°C for 3 hours. After the dried bamboo fibers are laid out, they are hot-pressed in a hot press at 150°C and 2.5MPa for 70 minutes. After cooling to room temperature, the reconstituted bamboo board is produced.

[0092] Comparative Example 1: The difference between Comparative Example 1 and Example 2 is that the functionalized ionic liquid prepared according to Preparation Example 2 is replaced with the functionalized ionic liquid prepared according to Comparative Preparation Example 1.

[0093] Comparative Example 2: The difference between Comparative Example 2 and Example 2 is that the functionalized ionic liquid prepared according to Preparation Example 2 is replaced with the functionalized ionic liquid prepared according to Comparative Preparation Example 2.

[0094] Comparative Example 3: The difference between Comparative Example 3 and Example 2 is that the bis(3-formylphenyl) peroxide dicarbonate prepared according to Preparation Example 5 is replaced with the bis(3-formylphenyl) peroxide dicarbonate prepared according to Comparative Preparation Example 3.

[0095] Comparative Example 4: The difference between Comparative Example 4 and Example 2 is that the poly(glycidyl methacrylate-co-styrene) prepared according to Preparation Example 8 is replaced with the poly(glycidyl methacrylate-co-styrene) prepared according to Comparative Preparation Example 4.

[0096] Comparative Example 5: The difference between Comparative Example 5 and Example 2 is that the poly(glycidyl methacrylate-co-styrene) prepared according to Preparation Example 8 is replaced with the poly(glycidyl methacrylate-co-styrene) prepared according to Comparative Preparation Example 5.

[0097] Comparative Example 6: The difference between Comparative Example 6 and Example 2 is that during S4 crosslinking and curing, after the bamboo fibers have completed crosslinking and carbonization, they are directly heated to 95°C and reacted for 2 hours in the original carbonizing agent, while the other steps remain unchanged.

[0098] Comparative Example 7: The difference between Comparative Example 7 and Example 2 is that 3-5 year old moso bamboo is first carbonized, then drawn into fibers, then cross-linked and cured, and finally hot-pressed. The specific process flow is as follows: A reconstituted bamboo board carbonization and fiber drawing integrated processing technology includes the following steps:

[0099] S1. Preparation of carbonizing agent: Add 3.5 kg of the functionalized ionic liquid prepared according to Preparation Example 2 to 3.5 kg of deionized water and stir for 35 min. Then add 600 g of bis(3-formylphenyl) peroxide dicarbonate prepared according to Preparation Example 5, 400 g of poly(glycidyl methacrylate-co-styrene) prepared according to Preparation Example 8 and 1.5 kg of N-methylpyrrolidone in sequence, and continue stirring for 1.5 h to obtain the carbonizing agent.

[0100] S2. Impregnation and carbonization: Select 3-5 year old moso bamboo, remove the bamboo nodes and outer skin, cut the bamboo into 250mm long sections, immerse them in carbonizing agent, heat to 55℃, stir, react for 3 hours to complete the carbonization process.

[0101] S3. Bamboo filament drawing: A double-roller bamboo filament drawing machine with a roller speed of 250 r / min is used to draw the carbonized bamboo segments into bamboo filaments with a thickness of 0.75 mm and a width of 2.5 mm. During the bamboo filament drawing process, deionized water is sprayed at a flow rate of 7 mL / min to prevent the bamboo filaments from overheating. The bamboo filaments after drawing are placed in an ultrasonic cleaning tank (power 500 W, frequency 15 kHz) and immersed in deionized water. The bamboo filaments are ultrasonically treated for 10 min, then removed and drained to obtain activated bamboo filaments.

[0102] S4. Crosslinking and curing: After the bamboo fibers are drawn and activated, they are immersed in deionized water containing 3% sodium hydroxide, heated to 95°C, and stirred for 2 hours to complete the crosslinking and curing.

[0103] S5. Drying and Hot Pressing: The cross-linked and cured bamboo fibers are filtered and separated from deionized water containing 3% sodium hydroxide. After washing with deionized water, the bamboo fibers are dried in a forced-air drying oven at 80°C for 2 hours. After the dried bamboo fibers are laid out, they are hot-pressed in a hot press at 140°C and 2MPa for 55 minutes. After cooling to room temperature, the reconstituted bamboo board is produced.

[0104] Comparative Example 8: The difference between Comparative Example 8 and Example 2 is that Comparative Example 8 uses reconstituted bamboo boards prepared by drawing bamboo that has not undergone any carbonization treatment.

[0105] Comparative Example 9: The difference between Comparative Example 9 and Example 2 is that Comparative Example 9 uses reconstituted bamboo boards prepared by physical carbonization and wire drawing.

[0106] Performance testing:

[0107] 1. The reconstituted bamboo boards prepared in Examples 1-3 and Comparative Examples 1-9 were tested for water absorption width expansion rate and water absorption thickness expansion rate according to the dimensional stability requirements of outdoor reconstituted bamboo in the national standard GB / T 30364-2024 "Reconstituted Bamboo Flooring". The test results are shown in Table 1.

[0108] 2. The reconstituted bamboo boards prepared in Examples 1-3 and Comparative Examples 1-9 were tested for static bending strength, modulus of elasticity and internal bonding strength according to the national standard GB / T 17657-2022 "Test Methods for Physical and Chemical Properties of Wood-based Panels and Decorative Wood-based Panels" using the three-point bending method. The test results are shown in Table 1.

[0109] 3. The recombinant bamboo boards prepared in Examples 1-3 and Comparative Examples 1-9 were inoculated with a mixed spore suspension of Aspergillus niger and Trichoderma according to the industry standard JIS Z 2801-2000 "Antibacterial Processed Products - Antibacterial Test Methods, Antibacterial Effects" and cultured at 28℃ for 28 days. The mold growth level was observed: Level 0: No growth (no mold visible to the naked eye); Level 1: Trace growth (coverage area < 10%); Level 2: Slight growth (coverage area ≤ 30%); Level 3: Moderate growth (coverage area ≤ 70%); Level 4: Severe growth (coverage area > 70%). The experimental results are shown in Table 1.

[0110] Table 1 Performance Test Results

[0111] Water absorption width expansion rate / % Water absorption thickness swelling rate / % Static bending strength / MPa Elastic modulus / MPa Internal bond strength / MPa Mold growth level Example 1 0.39 1.28 118.6 10230 1.3 Level 0 Example 2 0.33 1.13 122.5 10560 1.4 Level 0 Example 3 0.36 1.21 120.3 10380 1.3 Level 0 Comparative Example 1 2.88 4.27 82.4 7150 0.8 Level 3 Comparative Example 2 3.17 4.56 78.6 6890 0.7 Level 3 Comparative Example 3 2.18 3.87 86.9 7520 0.9 Level 2 Comparative Example 4 1.83 3.28 98.5 8340 1.0 Level 1 Comparative Example 5 2.58 4.08 80.2 6570 0.7 Level 3 Comparative Example 6 0.86 2.38 105.3 9210 1.1 Level 1 Comparative Example 7 1.23 2.88 100.7 8960 1.1 Level 1 Comparative Example 8 1.62 12.37 62.5 5120 0.5 Level 4 Comparative Example 9 0.91 9.83 92.3 7850 1.0 Level 2

[0112] Performance Analysis:

[0113] As can be seen from the experimental data in Table 1, the recombinant bamboo boards prepared by the present invention in Examples 1-3 all show significant advantages in water absorption and swelling control, mechanical strength and antibacterial and anti-corrosion properties. Among them, Example 2 has the best overall performance, with excellent mechanical strength and antibacterial effect based on extremely low water absorption and swelling rate.

[0114] The low water absorption and swelling rate of Example 2 is mainly due to the efficient sealing of cellulose hydroxyl groups and the physical barrier of water molecule penetration by the three-dimensional cross-linking network. The molecular structure of the functionalized ionic liquid (containing imidazole ring cation, carboxyethyl side chain and p-hydroxybenzoate anion) achieves deep swelling of bamboo fibers through multiple actions: the imidazole ring forms hydrogen bonds with the cellulose hydroxyl group, the carboxyethyl group forms additional hydrogen bonds with the cellulose chain, and the benzene ring of the p-hydroxybenzoate group produces π-π stacking with the aromatic region of cellulose. The synergistic effect of the three causes the molecular chain spacing inside the bamboo fibers to increase and the porosity to improve, providing channels for the subsequent penetration of cross-linking agents.

[0115] The aldehyde-containing derivative (3-formylphenyl carbonate) produced by the decomposition of bis(3-formylphenyl) peroxide dicarbonate undergoes a condensation reaction between its aldehyde group and the hydroxyl groups of cellulose in an alkaline crosslinking environment, directly blocking some of the hydroxyl groups in cellulose. Simultaneously, the epoxy groups in poly(glycidyl methacrylate-co-styrene) are nucleophilically attacked by the cellulose hydroxyl groups under alkaline conditions, undergoing a ring-opening addition reaction to form another type of covalent bond, further blocking the remaining hydroxyl groups in cellulose. The three-dimensional network constructed by these two reactions "locks" the cellulose molecular chain, significantly reducing its affinity for water molecules.

[0116] In comparison, Comparative Example 1, due to the replacement of 3-bromopropionic acid with bromobutane in the functionalized ionic liquid, lacked a carboxyethyl side chain and could not form multiple hydrogen bonds with cellulose, resulting in insufficient swelling rate, difficulty for the carbonizing agent component to penetrate the interior, insufficient hydroxyl group blocking rate, and a significantly increased water absorption swelling rate. Comparative Example 2 omitted the anion exchange step and retained 1-carboxyethyl-3-methylimidazolium bromide. The electrostatic repulsion between bromide ions and cellulose was stronger than the affinity of p-hydroxybenzoate, resulting in a worse swelling effect and insufficient cross-linking. Comparative Example 3 used benzoyl peroxide (without aldehyde group), which could only oxidize a small number of hydroxyl groups through free radicals and lacked aldehyde group condensation blocking effect, resulting in weak swelling control ability. Comparative Example 4, with its polyglycidyl methacrylate lacking styrene segments, had insufficient van der Waals forces with the hydrophobic regions of cellulose, making the segments easy to detach from the cellulose network, leading to the re-exposure of some hydroxyl groups, and a higher swelling rate than Example 2. Comparative Examples 8-9, due to the lack of chemical cross-linking or only physical carbonization, allowed water molecules to freely enter the inter-chain space, resulting in a much higher swelling rate than Example 2.

[0117] The excellent mechanical properties (static bending strength, elastic modulus, and internal bond strength) of Example 2 are essentially due to the integrated structure of the "cellulose skeleton-crosslinked network" constructed by chemical covalent bonds. After swelling with the functionalized ionic liquid, the crystalline regions of cellulose partially disintegrate, but retain most of the ordered structure as a rigid skeleton. The tensile strength of the molecular chains themselves provides the basis for the mechanical properties. At the same time, the condensation bonds between the aldehyde groups of bis(3-formylphenyl)peroxide dicarbonate and the hydroxyl groups of cellulose, and the ring-opening bonds between the epoxy groups of the copolymer and the hydroxyl groups, form dense crosslinking points between the cellulose chains, connecting the dispersed cellulose chains into a three-dimensional network. Stress can be quickly transferred to the entire structure through covalent bonds, avoiding local breakage. From the perspective of interfacial bonding, the styrene segments in the copolymer have hydrophobic interactions with the hydrophobic regions of cellulose, strengthening both the interfaces within and between bamboo fibers through "covalent bonds + physical interactions," significantly improving the internal bond strength. The hot-pressing stage further promotes the reaction of unreacted active groups (residual aldehyde groups and epoxy groups), making the crosslinked network denser, and the elastic modulus increases due to the increased proportion of rigid structure.

[0118] Due to structural defects in the functionalized ionic liquids, Comparative Examples 1-2 experienced insufficient swelling, resulting in the crosslinking agent only accumulating on the surface of the bamboo fibers. The internal cellulose chains were not effectively connected, and the surface crosslinked layer easily peeled off from the internal fibers under stress, leading to a significant decrease in mechanical strength. Comparative Example 3, containing benzoyl peroxide, lacked aldehyde groups and relied solely on copolymer epoxy groups for crosslinking, resulting in lower crosslinking density and weak network carrying capacity. Comparative Example 5, containing polystyrene, lacked epoxy groups and could not form covalent bonds with cellulose, relying only on physical entanglement. Under stress, the chain segments easily slipped, resulting in low internal bonding strength. Comparative Example 6, due to the lack of water replacement, saw residual oligosaccharides and amino acids competing with cellulose hydroxyl groups for reaction sites, leading to fewer crosslinking points and a looser network. Comparative Example 7, which underwent carbonization followed by fiber drawing, had its crosslinked structure mechanically damaged during the drawing process, resulting in microcracks inside the bamboo fibers and decreased strength. Comparative Examples 8-9, lacking chemical crosslinking, relied solely on inter-fiber friction and hot-pressing physical bonding, causing the fibers to easily slip under stress, resulting in strength far lower than Example 2.

[0119] Example 2 exhibits excellent antibacterial and antiseptic properties (no mold growth), primarily due to the synergistic effect of complete starch and protein degradation and improved hydrophobicity of bamboo fibers. Under the catalysis of a functionalized ionic liquid (transferring protons from the carboxyl group to the peroxide bond, thus lowering the bond energy), bis(3-formylphenyl) peroxide dicarbonate efficiently homolytically cleaves the peroxide bond to generate free radicals, which attack the α-1,4 glycosidic bonds of starch and the peptide bonds of proteins: starch chains are broken into small molecules such as glucose, and proteins are decomposed into amino acids. These degradation products diffuse to the surface through the pores of the swollen bamboo fibers and are thoroughly removed by washing, cutting off the nutrient source for mold. Simultaneously, the cross-linked network blocks the hydroxyl groups of cellulose, significantly reducing the water absorption rate of the bamboo fibers, and the low-humidity environment further inhibits mold spore germination.

[0120] In comparison, the functionalized ionic liquids of Comparative Examples 1-2, lacking carboxyethyl or p-hydroxybenzoate groups, exhibited low catalytic efficiency, decreased peroxy bond homolytic cleavage rate, and incomplete starch / protein degradation. The remaining oligosaccharides and amino acids became a culture medium for mold, leading to its extensive growth. Benzoyl peroxide in Comparative Example 3, lacking aldehyde groups, resulted in incomplete cellulose hydroxyl group closure and high water absorption, contributing to mold growth. Comparative Example 8, without carbonization treatment, retained the starch and protein intact in the bamboo fibers, allowing mold to multiply rapidly using them as a nutrient source. The physical carbonization of Comparative Example 9 only denatured some starch but failed to break glycosidic bonds, and the protein was not completely decomposed. The remaining components could still support mold growth. Furthermore, the high water absorption and swelling rate of Comparative Example 9 indicated insufficient hydrophobicity, thus its antibacterial effect was far inferior to that of Example 2.

[0121] 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 inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A process for integrated carbonization and wire drawing of reconstituted bamboo boards, characterized in that, Includes the following steps: S1. Bamboo Fiber Activation: Select 3-5 year old moso bamboo, remove the nodes and outer skin, cut the bamboo into sections with a length of 200-300mm, and use a double roller bamboo fiber drawing machine at a speed of 200-300r / min to draw the bamboo sections into bamboo fibers with a thickness of 0.5-1mm and a width of 2-3mm. During the bamboo fiber drawing process, spray deionized water at a flow rate of 5-10mL / min to prevent the bamboo fibers from overheating. Place the bamboo fibers into an ultrasonic cleaning tank with a power of 300-700W and a frequency of 10-20kHz, immerse the bamboo fibers in deionized water, and ultrasonically treat for 5-15 minutes. Remove and drain to obtain activated bamboo fibers. S2. Preparation of carbonizing agent: Add functionalized ionic liquid to deionized water and stir for 30-40 min. Then add bis(3-formylphenyl) peroxide dicarbonate, poly(glycidyl methacrylate-co-styrene) and N-methylpyrrolidone in sequence and continue stirring for 1-2 h to obtain carbonizing agent. S3. Impregnation and carbonization: Immerse the activated bamboo fibers in the carbonizing agent, heat to 50-60℃, and stir for 2-4 hours to complete the carbonization process; S4. Crosslinking and curing: After the carbonization process is completed, the bamboo fibers are taken out of the carbonizing agent and drained. They are washed three times with deionized water and then immersed in deionized water containing 3% sodium hydroxide. The temperature is raised to 90-100℃ and the reaction is stirred for 1-3 hours to complete the crosslinking and curing. S5. Drying and Hot Pressing: The cross-linked and cured bamboo fibers are filtered and separated from deionized water containing 3% sodium hydroxide. After washing with deionized water, the fibers are dried in a forced-air drying oven at 75-85℃ for 1-3 hours. After the dried bamboo fibers are laid out, they are hot-pressed in a hot press at 130-150℃ and 1.5-2.5MPa pressure for 40-70 minutes. After cooling to room temperature, the reconstituted bamboo board is produced.

2. The integrated carbonization and wire drawing process for reconstituted bamboo boards according to claim 1, characterized in that, In the S2 component, the functionalized ionic liquid, deionized water, bis(3-formylphenyl) peroxide dicarbonate, poly(glycidyl methacrylate-co-styrene) and N-methylpyrrolidone are in a weight ratio of 30-40:30-40:5-7:3-5:10-20.

3. The integrated carbonization and wire drawing process for reconstituted bamboo boards according to claim 1, characterized in that, The specific preparation method of the functionalized ionic liquid in S2 is as follows: (1) Add N-methylimidazolium to acetonitrile, heat to 50-70℃ with stirring, add 3-bromopropionic acid dropwise for 1-2 hours, and after the addition is complete, heat to 80-90℃ and react for 3-5 hours. Concentrate under reduced pressure to remove the solvent, and recrystallize the remaining product in ethanol to obtain 1-carboxyethyl-3-methylimidazolium bromide. (2) Add 1-carboxyethyl-3-methylimidazolium bromide to methanol, stir for 10-20 min, then add sodium p-hydroxybenzoate, heat to 60-70℃, react for 2-4 h, cool to room temperature, filter, concentrate the filtrate under reduced pressure to remove solvent, dissolve the product in deionized water, purify by 732 cation exchange resin column, collect the effluent and dry to obtain functionalized ionic liquid.

4. The integrated carbonization and wire drawing process for reconstituted bamboo boards according to claim 3, characterized in that, In (1), the molar ratio of N-methylimidazole and 3-bromopropionic acid is 1:1-1.4, and the weight ratio of N-methylimidazole and acetonitrile is 1:8-12.

5. The integrated carbonization and wire drawing process for reconstituted bamboo boards according to claim 3, characterized in that, In (2), the molar ratio of 1-carboxyethyl-3-methylimidazolium bromide and sodium p-hydroxybenzoate is 1:1-1.2, and the weight ratio of 1-carboxyethyl-3-methylimidazolium bromide and methanol is 1:8-12.

6. The integrated carbonization and wire drawing process for reconstituted bamboo boards according to claim 1, characterized in that, The specific preparation method of the bis(3-formylphenyl) peroxide dicarbonate in S2 is as follows: (a) In the reaction vessel of the tail gas absorption device, add 3-formylbenzoic acid, anhydrous DMF and anhydrous toluene, stir and cool down to below 0°C, add oxalyl chloride dropwise over 1-2 hours, and control the temperature to not exceed 5°C during the dropwise addition. After the dropwise addition is complete, restore the room temperature and react for 2-4 hours. Concentrate under reduced pressure to remove the solvent. The remaining product is recrystallized in anhydrous toluene / anhydrous n-hexane mixed solution to obtain the acyl chloride intermediate. (b) Add the acyl chloride intermediate and triethylamine to anhydrous dichloromethane, stir and cool to below 0°C, add a 30% hydrogen peroxide solution dropwise over 1-2 hours, controlling the temperature to not exceed 5°C during the dropwise addition, and continue the reaction for 1-2 hours after the addition is complete. Add deionized water to quench the reaction, collect the organic phase by separation, wash the organic phase with saturated sodium bicarbonate and deionized water respectively, dry it with anhydrous sodium sulfate, concentrate under reduced pressure to remove the solvent, and recrystallize the crude product in a mixed solution of ethyl acetate / petroleum ether to obtain bis(3-formylphenyl) peroxide dicarbonate.

7. The integrated carbonization and wire drawing process for reconstituted bamboo boards according to claim 6, characterized in that, In (a), the molar ratio of 3-formylbenzoic acid and oxaloyl chloride is 1:0.5-0.7, the weight ratio of 3-formylbenzoic acid, anhydrous DMF and anhydrous toluene is 1:0.02-0.06:8-12, and the anhydrous toluene / anhydrous n-hexane mixed solution refers to the mixture of anhydrous toluene and anhydrous n-hexane in a weight ratio of 3:

1.

8. The integrated carbonization and wire drawing process for reconstituted bamboo boards according to claim 6, characterized in that, In (b), the molar ratio of the acyl chloride intermediate and the hydrogen peroxide in the 30% hydrogen peroxide solution is 1:1-1.2, the weight ratio of the acyl chloride intermediate, triethylamine and anhydrous dichloromethane is 1:0.02-0.06:8-12, and the ethyl acetate / petroleum ether mixed solution refers to the mixture of ethyl acetate and petroleum ether in a weight ratio of 1:

3.

9. The integrated carbonization and wire drawing process for reconstituted bamboo boards as described in claim 1, characterized in that, The specific preparation method of poly(glycidyl methacrylate-co-styrene) in S2 is as follows: Under nitrogen protection, glycidyl methacrylate, styrene, azobisisobutyronitrile, benzyl dithiobenzoate and tetrahydrofuran were added to a reaction vessel and stirred for 20-40 min. Then the temperature was raised to 65-75℃ and the reaction was carried out for 5-7 h. After the reaction was completed, the reaction solution was poured into methanol to precipitate, the precipitate was collected, washed and dried to obtain poly(glycidyl methacrylate-co-styrene).

10. The integrated carbonization and wire drawing process for reconstituted bamboo boards as described in claim 9, characterized in that, The glycidyl methacrylate, styrene, and methyl methacrylate are present in a molar ratio of 3:1-2, and the glycidyl methacrylate, azobisisobutyronitrile, benzyl dithiobenzoate, and tetrahydrofuran are present in a weight ratio of 1:0.005-0.015:0.003-0.007:8-12.

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