Antibacterial bamboo integrated material enhanced by montmorillonite composite antibacterial agent and preparation method thereof

Abstract

This invention relates to an antibacterial bamboo laminated timber reinforced with montmorillonite composite antibacterial agent and its preparation method, belonging to the field of bamboo laminated timber technology. This invention utilizes the interlayer structure of montmorillonite as a "nanocontainer," loading quaternary ammonium salts through ion exchange and physical adsorption to achieve the slow and controllable release of antifungal active ingredients, significantly reducing loss caused by rainwater erosion or moisture, and extending the antifungal effectiveness period. The mineral carrier montmorillonite itself has a certain physical barrier effect, effectively inhibiting the penetration of moisture and oxygen, synergistically enhancing the antifungal and anti-aging properties with the chemical bactericidal effect of quaternary ammonium salts and the waterproof sealing effect of wood wax oil. The core components—quaternary ammonium salts, montmorillonite, and wood wax oil—are all low-toxicity or environmentally friendly materials, avoiding the use of heavy metals and persistent organic pollutants.

Description

Technical Field

[0001] This invention relates to an antibacterial bamboo laminated timber reinforced with montmorillonite composite antibacterial agent and its preparation method, belonging to the field of bamboo laminated timber technology. Background Technology

[0002] Bamboo laminated lumber is an engineering material made from bamboo through oriented assembly, gluing, and pressing. It boasts advantages such as high strength, good toughness, and environmental friendliness and renewability, and has been widely used in furniture manufacturing, interior decoration, and building structures. However, as a natural biomass material, bamboo is rich in cellulose and hemicellulose, making it highly susceptible to the growth of mold, bacteria, and other microorganisms in warm, humid environments. This can lead to mildew and decay, affecting not only appearance and lifespan but also potentially causing health problems. Therefore, improving the antibacterial and anti-mildew properties of bamboo laminated lumber is crucial for expanding its application range and extending its service life.

[0003] Currently, the main methods for antibacterial and antifungal treatment of bamboo include surface coating and impregnation. Among them, surface coating has attracted much attention due to its simple process and minimal impact on the substrate properties. Commonly used antibacterial coatings mainly rely on the addition of inorganic antibacterial agents (such as nano-silver and nano-zinc oxide) or organic antibacterial agents (such as quaternary ammonium salts and isothiazolinones). However, these methods still have significant limitations: inorganic nanoparticles are prone to agglomeration, resulting in poor dispersion in the coating and potential biotoxicity; while small-molecule organic antibacterial agents suffer from problems such as easy migration, easy loss, and poor durability, making it difficult to guarantee long-term antibacterial effects, and they are prone to decomposition and failure under light or humid and hot environments.

[0004] Montmorillonite is a natural layered silicate mineral with characteristics such as large specific surface area, high ion exchange capacity, and good chemical stability. In recent years, using montmorillonite as a carrier to load organic antibacterial agents such as quaternary ammonium salts through ion exchange or intercalation to prepare organic-inorganic composite antibacterial materials has become a research hotspot. These composite materials are expected to combine the stability of inorganic carriers with the high efficiency of organic antibacterial agents, achieving sustained release and long-lasting effects of antibacterial components. However, existing montmorillonite composite antibacterial technologies still face a series of challenges when practically applied to bamboo coatings:

[0005] The contradiction between antibacterial efficacy and durability: In conventional ion exchange complexes, the binding force between antibacterial agents and montmorillonite is still mainly physical adsorption and ionic bonds. Under complex service environments (such as humidity changes and rain erosion), antibacterial components may still be gradually lost, resulting in a decline in long-lasting antibacterial and antifungal performance.

[0006] Insufficient overall performance of coatings: Most studies focus on antibacterial properties themselves, while neglecting other key properties required for coatings as protective layers. For example, simple montmorillonite-quaternary ammonium salt composites contribute little to improving the coating's UV aging resistance, and bamboo products are still prone to discoloration and chalking in outdoor or sun-exposed environments.

[0007] Therefore, there is an urgent need to develop an antibacterial bamboo laminated timber that can firmly adhere to bamboo and slowly release anti-mildew active ingredients, thereby achieving long-lasting, efficient, and environmentally friendly anti-mildew properties, as well as its preparation method. Summary of the Invention

[0008] The purpose of this invention is to provide an antibacterial bamboo laminated timber reinforced with montmorillonite composite antibacterial agent and its preparation method, so as to solve the problem of poor anti-mildew durability of current antibacterial bamboo laminated timber.

[0009] This invention provides a method for preparing antibacterial bamboo laminated timber reinforced with a montmorillonite composite antibacterial agent, comprising the following steps: compounding montmorillonite and a quaternary ammonium salt to obtain a quaternary ammonium salt-modified montmorillonite composite; then mixing the quaternary ammonium salt-modified montmorillonite composite with wood wax oil to obtain an anti-mildew coating liquid; finally, coating the anti-mildew coating liquid onto the surface of bamboo, and drying to obtain antibacterial bamboo laminated timber reinforced with a montmorillonite composite antibacterial agent; wherein the quaternary ammonium salt is a dodecyl dimethyl benzyl ammonium chloride or a mercapto quaternary ammonium salt modifier, and the chemical structure of the mercapto quaternary ammonium salt modifier is as follows:

[0010] .

[0011] Preferably, the method for compounding montmorillonite and quaternary ammonium salt is as follows: montmorillonite and quaternary ammonium salt are mixed in a solvent, then centrifuged, and the solid obtained by centrifugation is washed, dried, and ground to obtain a quaternary ammonium salt modified montmorillonite composite; the mixing temperature is 60~70℃ and the time is 8~10h.

[0012] Preferably, the mass ratio of montmorillonite to quaternary ammonium salt is 5:2.4~2.8.

[0013] Preferably, the montmorillonite is sodium-based montmorillonite.

[0014] Preferably, the sodium-based montmorillonite has a cation exchange capacity of 145-150 mmol / 100g and an average particle size of 5-8 μm.

[0015] Preferably, the mass ratio of the quaternary ammonium salt modified montmorillonite complex to the wood wax oil is 3~4:95~97; the wood wax oil is composed of linseed oil, carnauba wax and soybean oil in a mass ratio of 6~7:3~5:1~2.

[0016] Preferably, the method for mixing the quaternary ammonium salt-modified montmorillonite complex and wood wax oil is as follows: the quaternary ammonium salt-modified montmorillonite complex and wood wax oil are subjected to mechanical stirring and ultrasonic treatment sequentially; the mechanical stirring speed is 500~700 r / min, and the time is 30~50 min; the power density of the ultrasonic treatment is 0.5~0.6 W / cm³. 2 The time is 20-40 minutes.

[0017] Preferably, the anti-mildew coating liquid is applied to the bamboo surface in two coats, with each coat consisting of 40-50 g / m². 2 .

[0018] Preferably, the preparation method of the mercapto quaternary ammonium salt modifier is as follows: pentaerythritol tetramercaptoacetate and 1-vinyl-3-butylimidazolium bromide are mixed and reacted in a solvent under the action of a photoinitiator and ultraviolet light, and then mixed and reacted with propenyltriethylammonium bromide under the action of a photoinitiator and ultraviolet light to obtain the mercapto quaternary ammonium salt modifier; the molar ratio of pentaerythritol tetramercaptoacetate, 1-vinyl-3-butylimidazolium bromide and propenyltriethylammonium bromide is 1:1:1.

[0019] An antibacterial bamboo laminated timber prepared by the method described above for strengthening antibacterial bamboo laminated timber with montmorillonite composite antibacterial agent.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] (1) Long-lasting slow release and low loss rate: By utilizing the interlayer structure of montmorillonite as a "nano-container", quaternary ammonium salts were loaded through ion exchange and physical adsorption, achieving slow and controllable release of antifungal active ingredients, significantly reducing the loss caused by rainwater erosion or water erosion, and extending the antifungal efficacy period. Experiments have shown that the antifungal durability of the loaded complex is far superior to that of directly using quaternary ammonium salts.

[0022] (2) Synergistic protection: The mineral carrier montmorillonite itself has a certain physical barrier effect, which can effectively inhibit the penetration of water and oxygen. It works synergistically with the chemical bactericidal effect of quaternary ammonium salt and the waterproof sealing effect of wood wax oil to jointly improve the anti-mildew and anti-aging performance.

[0023] (3) Environmental protection and safety: The core components, quaternary ammonium salt, montmorillonite and wood wax oil, are all low-toxicity or environmentally friendly materials, avoiding the use of heavy metals and persistent organic pollutants.

[0024] (4) Excellent compatibility and film-forming properties: After modification with quaternary ammonium salt, the dispersibility of mineral carrier in wood wax oil is significantly improved, the composite coating is uniform, dense, free of agglomeration, has strong adhesion, and a smooth surface.

[0025] (5) Highly targeted: This invention is specifically designed for the dense structure of bamboo laminated timber and the difficulty of chemical penetration. Through surface film formation and slow release technology, it achieves long-term protection without relying on deep penetration, and can effectively protect the sides and ends that are prone to mold. Attached Figure Description

[0026] Figure 1 The X-ray diffraction (XRD) pattern of the quaternary ammonium salt modified montmorillonite composite prepared in Example 1 of this invention;

[0027] Figure 2 The 1H NMR spectrum of the thiol quaternary ammonium salt modifier prepared in Example 3 of this invention;

[0028] Figure 3 The image shows the appearance of the antibacterial bamboo laminated timber prepared in Example 1 of this invention after 11 months of storage under natural conditions. Detailed Implementation

[0029] The following examples are intended to further illustrate the content of the present invention, rather than to limit the scope of protection of the present invention.

[0030] Example 1

[0031] The preparation method of antibacterial bamboo laminated lumber reinforced with montmorillonite composite antibacterial agent in this embodiment includes the following steps:

[0032] (1) Take 5g of sodium montmorillonite (cation exchange capacity CEC of 145mmol / 100g, average particle size of 5μm) and disperse it in 75g of 50% ethanol aqueous solution to obtain sodium montmorillonite dispersion; dissolve 2.47g of dodecyl dimethyl benzyl ammonium chloride in 20g of deionized water to obtain dodecyl dimethyl benzyl ammonium chloride solution; then add the dodecyl dimethyl benzyl ammonium chloride solution to the sodium montmorillonite dispersion and mix mechanically at 60℃ (mechanical stirring speed of 600r / min) 8 h, then centrifuged (centrifugation speed 8000 r / min, time 15 min), the solid obtained by centrifugation was washed three times with deionized water (40 mL of deionized water each time) to reach the washing endpoint (the washing endpoint is judged as follows: take 5 mL of the washing liquid obtained after washing, add 1-2 drops of 0.1 mol / L silver nitrate aqueous solution, no white precipitate appears), and vacuum dry at 60℃ (absolute pressure maintained at 1 kPa in the vacuum drying oven) for 12 h to obtain the quaternary ammonium salt modified montmorillonite complex. The X-ray diffraction (XRD) pattern of the quaternary ammonium salt modified montmorillonite complex is shown below. Figure 1 ( Figure 1 The vertical axis represents intensity (the control sample is sodium-based montmorillonite, and the sample is a quaternary ammonium salt-modified montmorillonite composite). Figure 1It can be seen that, compared with the unmodified montmorillonite, the intensity of the diffraction peak at 2θ≈20° of the sample decreased and the peak shape broadened slightly, indicating that the quaternary ammonium salt interacted with the montmorillonite.

[0033] (2) 3g of quaternary ammonium salt-modified montmorillonite complex was added to 97g of wood wax oil (the wood wax oil was prepared by mixing linseed oil, carnauba wax and soybean oil in a mass ratio of 6:3:1 at 85°C and then cooling to room temperature), and mechanical stirring (mechanical stirring speed of 500r / min for 30min) and ultrasonic treatment (ultrasonic treatment power density of 0.5W / cm³) were carried out sequentially. 2 (At a frequency of 25kHz and a duration of 20min), an anti-mildew coating liquid was obtained.

[0034] (3) Sand the surface of the bamboo engineered wood (the specifications of the bamboo engineered wood are 1000mm×200mm×15mm, and the moisture content is 8%) (the sandpaper used for sanding is 240 grit) and clean it (the cleaning is done by wiping with ethanol). Then, apply the anti-mildew coating liquid evenly to the surface of the bamboo with a brush. Apply two coats in total (let it stand at room temperature for 12 hours after the first coat to dry before applying the second coat). The amount of coating each time is 50g / m². 2 Then, it is dried in an oven at 60℃ for 8 hours to obtain antibacterial bamboo laminated timber reinforced with montmorillonite composite antibacterial agent.

[0035] Example 2

[0036] The difference between the preparation method of antibacterial bamboo laminated timber reinforced with montmorillonite composite antibacterial agent in this embodiment and the preparation method of antibacterial bamboo laminated timber reinforced with montmorillonite composite antibacterial agent in Example 1 is that the vacuum drying temperature in step (1) of the preparation method of antibacterial bamboo laminated timber reinforced with montmorillonite composite antibacterial agent in this embodiment is adjusted from 60°C to 30°C.

[0037] Example 3

[0038] The preparation method of antibacterial bamboo laminated lumber reinforced with montmorillonite composite antibacterial agent in this embodiment includes the following steps:

[0039] (1) Add 0.1 mol of pentaerythritol tetramercaptoacetate and 400 mL of anhydrous tetrahydrofuran to the reaction flask, stir well, and then purge with nitrogen gas. Then add 0.005 mol of photoinitiator benzoin dimethyl ether and 0.1 mol of 1-vinyl-3-butylimidazolium bromide to the reaction flask, stir until the solid is fully dissolved, and then stir and react for 20 min under 365 nm ultraviolet light irradiation (ultraviolet light intensity is 30 mW / cm). 2With the light source 10 cm above the liquid surface and the stirring speed at 500 r / min, after turning off the UV light, 0.005 mol of photoinitiator benzoin dimethyl ether and 0.1 mol of propenyltriethylammonium bromide were added to the reaction flask. After stirring until the solids were fully dissolved, the reaction was continued under 365 nm UV light irradiation for 35 min with stirring (UV light source intensity 30 mW / cm²). 2 The light source was positioned 10 cm above the liquid surface, and the stirring speed was 500 r / min. Then, the UV light was turned off, and the reaction solution in the reaction flask was subjected to vacuum distillation to remove the solvent tetrahydrofuran, yielding a crude product. 300 mL of anhydrous diethyl ether was added to the crude product, and after stirring evenly, it was allowed to stand for 4 hours. The mixture was then filtered, and the filter cake was washed three times with anhydrous diethyl ether (50 mL each time). Finally, the washed solid was dried in a vacuum drying oven at 40 °C for 12 hours to obtain the thiol quaternary ammonium salt modifier. The 1H NMR spectrum of the thiol quaternary ammonium salt modifier is shown below. Figure 2 As shown, the chemical structure is as follows:

[0040] .

[0041] (2) Take 5g of sodium montmorillonite (cation exchange capacity CEC of 145mmol / 100g, average particle size of 5μm) and disperse it in 75g of ethanol to obtain sodium montmorillonite dispersion; dissolve 2.47g of mercapto quaternary ammonium salt modifier in 20g of ethanol to obtain mercapto quaternary ammonium salt modifier solution; then add mercapto quaternary ammonium salt modifier solution to sodium montmorillonite dispersion, and mechanically stir and mix at 60℃ (stirring speed of 600r / min) for 8h, and then centrifuge (centrifugation speed of 8000r / min). The solid obtained by centrifugation was washed three times with ethanol and then once with deionized water (40 mL of ethanol and 50 mL of deionized water were used for each wash) until the washing endpoint was reached (the washing endpoint was judged as follows: take 5 mL of the washing liquid obtained after washing with deionized water, add 1-2 drops of 0.1 mol / L silver nitrate aqueous solution, and no pale yellow precipitate appears). The solid was then vacuum dried at 60℃ (the absolute pressure in the vacuum drying oven was maintained at 1 kPa) for 12 h to obtain the quaternary ammonium salt modified montmorillonite complex.

[0042] (3) Add 3g of quaternary ammonium salt modified montmorillonite complex to 97g of wood wax oil (wood wax oil is prepared by mixing linseed oil, carnauba wax and soybean oil in a mass ratio of 6:3:1 at 85℃ and then cooling to room temperature), and then perform mechanical stirring (mechanical stirring speed of 500r / min for 30min) and ultrasonic treatment (ultrasonic power density of 0.5W / cm³) in sequence. 2 (At a frequency of 25kHz and a duration of 20min), an anti-mildew coating liquid was obtained.

[0043] (4) Sand the surface of the bamboo engineered wood (the specifications of the bamboo engineered wood are 1000mm×200mm×15mm, and the moisture content is 8%) (the sandpaper used for sanding is 240 mesh) and clean it (the cleaning is done by wiping with ethanol). Then, apply the anti-mildew coating liquid evenly to the surface of the bamboo material with a brush. Apply it twice (let it stand at room temperature for 12 hours after the first application to dry before applying the second application). The amount of coating each time is 50g / m². Then, dry it in an oven at 60℃ for 8 hours to obtain antibacterial bamboo engineered wood reinforced with montmorillonite composite antibacterial agent.

[0044] Comparative Example 1

[0045] The difference between the preparation method of the antibacterial bamboo laminated timber in this comparative example and the preparation method of the antibacterial bamboo laminated timber reinforced with montmorillonite composite antibacterial agent in Example 1 is that the mass fraction of the quaternary ammonium salt modified montmorillonite composite in the anti-mildew coating liquid used in step (2) of the preparation method of the antibacterial bamboo laminated timber in this comparative example is 0, that is, only wood wax oil is used to coat the surface of bamboo in this comparative example.

[0046] Comparative Example 2

[0047] The difference between the preparation method of the antibacterial bamboo laminated timber in this comparative example and the preparation method of the antibacterial bamboo laminated timber reinforced with montmorillonite composite antibacterial agent in Example 1 is that the anti-mildew coating liquid used in step (3) of the preparation method of the antibacterial bamboo laminated timber in this comparative example is that 1g of dodecyl dimethyl benzyl ammonium chloride is dispersed in 97g of wood wax oil (wood wax oil is prepared by stirring and mixing linseed oil, carnauba wax and soybean oil in a mass ratio of 6:3:1 at 85°C and then cooling to room temperature).

[0048] Comparative Example 3

[0049] The difference between the preparation method of the antibacterial bamboo laminated timber reinforced with montmorillonite composite antibacterial agent in this comparative example and the preparation method of the antibacterial bamboo laminated timber reinforced with montmorillonite composite antibacterial agent in Example 1 is that in step (1) of the preparation method of the antibacterial bamboo laminated timber reinforced with montmorillonite composite antibacterial agent in this comparative example, dodecyl dimethyl benzyl ammonium chloride is replaced with dialcyl dimethyl ammonium chloride.

[0050] Comparative Example 4

[0051] The difference between the preparation method of the antibacterial bamboo laminated timber reinforced with montmorillonite composite antibacterial agent in this comparative example and the preparation method of the antibacterial bamboo laminated timber reinforced with montmorillonite composite antibacterial agent in Example 3 is only that the step (1) of the preparation method of the antibacterial bamboo laminated timber reinforced with montmorillonite composite antibacterial agent in this comparative example is as follows: 0.1 mol of pentaerythritol tetramercaptoacetate and 400 mL of anhydrous tetrahydrofuran are added to the reaction flask, and after stirring evenly, nitrogen gas is introduced. Then, 0.01 mol of photoinitiator benzoin dimethyl ether and 0.2 mol of 1-vinyl-3-butylimidazolium bromide are added to the reaction flask. After stirring until the solid is fully dissolved, the reaction is carried out under 365 nm ultraviolet light irradiation for 55 min (ultraviolet light source intensity is 30 mW / cm). 2 The light source was positioned 10 cm above the liquid surface, and the stirring speed was 500 r / min. Then, the UV light was turned off, and the reaction solution in the reaction flask was subjected to vacuum distillation to remove the solvent tetrahydrofuran, yielding a crude product. 300 mL of anhydrous diethyl ether was added to the crude product, and after stirring evenly, it was allowed to stand for 4 hours. The mixture was then filtered, and the filter cake was washed three times with anhydrous diethyl ether (50 mL each time). Finally, the washed solid was dried in a vacuum drying oven at 40 °C for 12 hours to obtain a mercapto quaternary ammonium salt modifier. The chemical structure of the mercapto quaternary ammonium salt modifier is as follows:

[0052] .

[0053] Comparative Example 5

[0054] The difference between the preparation method of the antibacterial bamboo laminated timber reinforced with montmorillonite composite antibacterial agent in this comparative example and the preparation method of the antibacterial bamboo laminated timber reinforced with montmorillonite composite antibacterial agent in Example 3 is that the step (1) of the preparation method of the antibacterial bamboo laminated timber reinforced with montmorillonite composite antibacterial agent in this comparative example is as follows: 0.1 mol of pentaerythritol tetramercaptoacetate and 400 mL of anhydrous tetrahydrofuran are added to the reaction flask, stirred evenly, and nitrogen gas is introduced. Then, 0.01 mol of photoinitiator benzoin dimethyl ether and 0.2 mol of propenyl triethylammonium bromide are added to the reaction flask, stirred until the solid is fully dissolved, and then stirred and reacted under 365 nm ultraviolet light irradiation for 55 min (ultraviolet light source intensity is 30 mW / cm). 2 The light source was positioned 10 cm above the liquid surface, and the stirring speed was 500 r / min. Then, the UV light was turned off, and the reaction solution in the reaction flask was subjected to vacuum distillation to remove the solvent tetrahydrofuran, yielding a crude product. 300 mL of anhydrous diethyl ether was added to the crude product, and after stirring evenly, it was allowed to stand for 4 hours. The mixture was then filtered, and the filter cake was washed three times with anhydrous diethyl ether (50 mL each time). Finally, the washed solid was dried in a vacuum drying oven at 40 °C for 12 hours to obtain a mercapto quaternary ammonium salt modifier. The chemical structure of the mercapto quaternary ammonium salt modifier is as follows:

[0055] .

[0056] Comparative Example 6

[0057] The difference between the preparation method of the antibacterial bamboo laminated timber reinforced with montmorillonite composite antibacterial agent in this comparative example and the preparation method of the antibacterial bamboo laminated timber reinforced with montmorillonite composite antibacterial agent in Example 3 is only that the step (1) of the preparation method of the antibacterial bamboo laminated timber reinforced with montmorillonite composite antibacterial agent in this comparative example is as follows: 0.1 mol of pentaerythritol tetramercaptoacetate and 400 mL of anhydrous tetrahydrofuran are added to the reaction flask, and after stirring evenly, nitrogen gas is introduced. Then, 0.005 mol of photoinitiator benzoin dimethyl ether and 0.1 mol of 1-vinyl-3-butylimidazolium bromide are added to the reaction flask. After stirring until the solid is fully dissolved, the reaction is carried out under 365 nm ultraviolet light irradiation for 20 min (ultraviolet light source intensity is 30 mW / cm). 2 With the light source 10 cm above the liquid surface and the stirring speed at 500 r / min, after turning off the UV light, 0.01 mol of photoinitiator benzoin dimethyl ether and 0.2 mol of propenyltriethylammonium bromide were added to the reaction flask. After stirring until the solids were fully dissolved, the reaction was continued under 365 nm UV light irradiation for 60 min with stirring (UV light source intensity 30 mW / cm²). 2 The light source was positioned 10 cm above the liquid surface, and the stirring speed was 500 r / min. Then, the UV light was turned off, and the reaction solution in the reaction flask was subjected to vacuum distillation to remove the solvent tetrahydrofuran, yielding a crude product. 300 mL of anhydrous diethyl ether was added to the crude product, and after stirring evenly, it was allowed to stand for 4 hours. The mixture was then filtered, and the filter cake was washed three times with anhydrous diethyl ether (50 mL each time). Finally, the washed solid was dried in a vacuum drying oven at 40 °C for 12 hours to obtain a mercapto quaternary ammonium salt modifier. The chemical structure of the mercapto quaternary ammonium salt modifier is as follows:

[0058] .

[0059] Comparative Example 7

[0060] The difference between the preparation method of the antibacterial bamboo laminated timber reinforced with montmorillonite composite antibacterial agent in this comparative example and the preparation method of the antibacterial bamboo laminated timber reinforced with montmorillonite composite antibacterial agent in Example 3 is only that the step (1) of the preparation method of the antibacterial bamboo laminated timber reinforced with montmorillonite composite antibacterial agent in this comparative example is as follows: 0.1 mol of pentaerythritol tetramercaptoacetate and 400 mL of anhydrous tetrahydrofuran are added to the reaction flask, stirred evenly, and nitrogen gas is introduced. Then, 0.01 mol of photoinitiator benzoin dimethyl ether and 0.2 mol of 1-vinyl-3-butylimidazolium bromide are added to the reaction flask, stirred until the solid is fully dissolved, and stirred under 365 nm ultraviolet light irradiation for 45 min (ultraviolet light source intensity is 30 mW / cm).2 With the light source 10 cm above the liquid surface and the stirring speed at 500 r / min, after turning off the UV light, 0.005 mol of photoinitiator benzoin dimethyl ether and 0.1 mol of propenyltriethylammonium bromide were added to the reaction flask. After stirring until the solids were fully dissolved, the reaction was continued under 365 nm UV light irradiation for 35 min with stirring (UV light source intensity 30 mW / cm²). 2 The light source was positioned 10 cm above the liquid surface, and the stirring speed was 500 r / min. Then, the UV light was turned off, and the reaction solution in the reaction flask was subjected to vacuum distillation to remove the solvent tetrahydrofuran, yielding a crude product. 300 mL of anhydrous diethyl ether was added to the crude product, and after stirring evenly, it was allowed to stand for 4 hours. The mixture was then filtered, and the filter cake was washed three times with anhydrous diethyl ether (50 mL each time). Finally, the washed solid was dried in a vacuum drying oven at 40 °C for 12 hours to obtain a mercapto quaternary ammonium salt modifier. The chemical structure of the mercapto quaternary ammonium salt modifier is as follows:

[0061] .

[0062] Comparative Example 8

[0063] The difference between the preparation method of the antibacterial bamboo laminated timber reinforced with montmorillonite composite antibacterial agent in this comparative example and the preparation method of the antibacterial bamboo laminated timber reinforced with montmorillonite composite antibacterial agent in Example 3 is that the quaternary ammonium salt modified montmorillonite composite in step (3) of the preparation method of the antibacterial bamboo laminated timber reinforced with montmorillonite composite antibacterial agent in this comparative example is composed of sodium montmorillonite and mercapto quaternary ammonium salt modifier in a mass ratio of 5:2.47. The sodium montmorillonite is the same as the sodium montmorillonite in step (2) of the preparation method of the antibacterial bamboo laminated timber reinforced with montmorillonite composite antibacterial agent in Example 3, and the mercapto quaternary ammonium salt modifier is the same as the mercapto quaternary ammonium salt modifier in step (2) of the preparation method of the antibacterial bamboo laminated timber reinforced with montmorillonite composite antibacterial agent in Example 3.

[0064] Experimental Example

[0065] This experimental example is used to evaluate the anti-mildew and aging resistance of the antibacterial bamboo laminated timber prepared in each embodiment and comparative example. The test method for anti-mildew performance is as follows: Antibacterial bamboo laminated timber was cut into 50mm×50mm×20mm samples and placed statically in an accelerated testing chamber at a constant temperature of 28℃ and relative humidity of RH90%. The chamber was periodically (every 3 days) sprayed with a mixed mold spore suspension of Aspergillus niger + Aspergillus flavus + Trichoderma (spore concentration 1×10⁻⁶). 7 CFU / mL, spraying rate 5mL / m² per application 2The samples were cultured in the dark throughout the process, and the surface mold was observed daily. The time when the earliest visible mold colonies (minimum colony diameter 0.5 mm) appeared on the surface of the antibacterial bamboo laminated timber was recorded as the number of days of antibacterial performance. The aging resistance test method is as follows: the antibacterial bamboo laminated timber was subjected to a 40-hour ultraviolet aging test. The difference in lightness ΔL, red-green index Δa, and yellow-blue index Δb of the antibacterial bamboo laminated timber before and after the ultraviolet aging test were measured and calculated using a colorimeter. The test results are shown in Table 1. Among them, the appearance of the antibacterial bamboo laminated timber prepared in Example 1 after 11 months of storage under natural conditions is shown in the following image. Figure 3 As shown.

[0066] Table 1. Anti-mildew and aging resistance properties of antibacterial bamboo laminated lumber

[0067]

[0068] As shown in Table 1, Example 1 exhibits significant advantages over Comparative Example 1 in both anti-mold and anti-aging performance. This indicates that the montmorillonite composite antibacterial agent used in Example 1 not only provides continuous antibacterial function but also enhances the physical barrier and UV stability of the coating through its nano-layered structure. Montmorillonite, as a layered silicate, has a high specific surface area and ion exchange capacity, allowing it to load quaternary ammonium salts. The quaternary ammonium salts enter the interlayer of montmorillonite through ion exchange and are slowly released during use, providing long-lasting antibacterial properties. Moreover, montmorillonite itself has a certain ability to adsorb bacteria, synergistically enhancing the antibacterial effect with quaternary ammonium salts. In addition, montmorillonite has excellent UV blocking ability, scattering and absorbing ultraviolet rays to protect the wood wax oil matrix. The layered structure of montmorillonite enhances the density of the coating, not only hindering the attachment and growth of mold spores but also reducing oxygen and moisture penetration and delaying photo-oxidation. Quaternary ammonium salts have a certain free radical scavenging ability, synergistically slowing down coating aging with montmorillonite. In contrast, the wood wax oil used in Comparative Example 1 does not have antibacterial activity, cannot inhibit mold growth, and does not have anti-mold activity. Mold can easily grow on the surface, so the anti-mold time is short. Furthermore, wood wax oil is prone to oxidation and yellowing under ultraviolet light, resulting in significant color changes.

[0069] As shown in Example 1 and Comparative Example 2, quaternary ammonium salts directly dispersed in wood wax oil possess certain antibacterial properties, but lacking the carrier support of montmorillonite, they are released and lost quickly, and cannot form a stable and durable antibacterial layer on the bamboo surface. Furthermore, the uncomposite quaternary ammonium salts are unevenly distributed in the coating and are easily degraded by environmental factors (such as moisture and ultraviolet radiation), resulting in a short-lived anti-mildew effect. In addition, quaternary ammonium salts themselves do not possess ultraviolet shielding capabilities; therefore, the antibacterial bamboo laminated timber prepared in Comparative Example 2 has weak resistance to ultraviolet aging and is prone to yellowing.

[0070] Both Example 1 and Comparative Example 3 employed a composite structure of quaternary ammonium salt modified montmorillonite, but significant differences were observed in their antifungal and aging resistance properties. This indicates that the structure of the quaternary ammonium salt also affects the performance of the composite antibacterial agent and the prepared antibacterial bamboo laminated timber. The dodecyl dimethyl benzyl ammonium chloride used in Example 1 contains benzyl groups in addition to long-chain alkyl groups. This benzyl structure enhances the affinity for aromatic components in microbial cell membranes through π-π interactions and can more effectively disrupt cell membrane integrity, exhibiting stronger antibacterial activity. In contrast, the dialcyl dimethyl ammonium chloride used in Comparative Example 3 has a double long-chain structure. Although it also possesses antibacterial properties, its mechanism of action mainly relies on hydrophobic interactions. Under the same loading, its immediate killing efficacy and long-term antibacterial effect against test bacteria such as Escherichia coli are inferior to the former. The presence of the benzyl group may enhance the interaction between the quaternary ammonium salt molecule and the montmorillonite sheets, making the binding of the antibacterial agent in Example 1 more stable in the carrier, achieving a more gradual and sustained release, thereby extending the antifungal time. In Example 1, the composite system of dodecyl dimethyl benzyl ammonium chloride and montmorillonite is more stable and can more effectively maintain the integrity of its nanosheet structure during UV aging, thus continuously exerting excellent UV shielding properties. The stable composite helps to form a dense, uniform nanocomposite network in the wood wax oil coating. This network can effectively block the penetration of oxygen and water molecules, delaying the photo-oxidation process of the coating substrate.

[0071] Compared to Example 3, the thiol quaternary ammonium salt modifier prepared in Comparative Example 4 contains only imidazolium bromide, and the thiol quaternary ammonium salt modifier prepared in Comparative Example 5 contains only ammonium bromide. The single cationic structure leads to a decrease in the antibacterial spectrum and bactericidal efficiency, and may also affect the binding strength or release behavior with montmorillonite, resulting in insufficient long-term retention of the antibacterial component and poor antifungal durability. In contrast, the thiol quaternary ammonium salt modifier prepared in Example 3 integrates two cationic active centers: imidazolium salt and trialkylammonium salt. Due to its planar conjugated structure and charge delocalization characteristics, imidazolium salt has extremely strong electrostatic adsorption and penetration capabilities for microbial cell membranes; while the long-chain alkyl group of trialkylammonium salt can effectively disrupt the lipid bilayer structure. The two work synergistically on the same molecular chain, achieving multi-site and multi-mechanism attack on the cell membrane, thereby producing antibacterial efficacy far exceeding that of a single component. The thiol group at the end of the thiol quaternary ammonium salt modifier can act as a strong anchoring group, forming a stable chemical bond with montmorillonite, effectively reducing the physical loss of the antibacterial component. Furthermore, the two cationic active centers ensure a more uniform molecular-level dispersion of the thiol quaternary ammonium salt modifier on the montmorillonite surface and in the wood wax oil coating. This highly dispersed nanocomposite system can construct a denser UV shielding network and effectively block the penetration of oxygen and moisture, thereby reducing photo-oxidation and yellowing caused by UV aging.

[0072] Compared to Example 3, the thiol quaternary ammonium salt modifier used in Comparative Examples 6-7 contains only one thiol group, which may lead to a decrease in the ability of the thiol quaternary ammonium salt modifier to form a strong chemical bond with montmorillonite. Moreover, the thiol quaternary ammonium salt modifier used in Comparative Examples 6-7 has too many molecular branches, and some active sites are buried inside the molecule or aggregated, resulting in a significant decrease in spatial accessibility and severely weakening the apparent antibacterial activity.

[0073] Compared to Example 3, Comparative Example 8 involved a simple physical mixing of the thiol quaternary ammonium salt modifier and sodium-based montmorillonite, without any in-solution mixing or composite modification process. The modifier and montmorillonite were only bound by weak van der Waals forces or electrostatic attraction, resulting in a loose and unstable physical adsorption state. During subsequent coating liquid preparation and film formation, the modifier was prone to desorption, migration, aggregation, or loss from the montmorillonite surface, failing to form an effective and durable antibacterial layer on the bamboo surface. Furthermore, physical mixing could not alter the aggregation state of montmorillonite, which might exist as aggregates in the coating, failing to form an effective nano-shielding network and potentially accelerating coating aging due to interfacial defects. In contrast, in Example 3, under heating and stirring conditions, the thiol groups at the ends of the modifier and the cationic groups on the polymer chains could undergo chemical adsorption, ion exchange, and even covalent bonding with the hydroxyl groups at the edges of the montmorillonite sheets and the exchangeable cations between the layers. This process allowed the modifier molecules to firmly insert into and anchor within the interlayers and surface of the montmorillonite, forming a structurally stable organic-inorganic nano-hybrid material. This structure ensures the long-term stable presence and controlled release of antibacterial active ingredients. Through chemical compounding, intercalation or exfoliation-type nanocomposite structures allow montmorillonite nanosheets to be uniformly and stably dispersed in the modifier and the final wood wax oil coating. This nanodispersion system efficiently scatters and absorbs ultraviolet light and significantly extends the penetration pathways of aging factors such as oxygen and moisture, thus providing excellent protection for the bamboo matrix.

Claims

1. A method for preparing antibacterial bamboo laminated lumber reinforced with montmorillonite composite antibacterial agent, characterized in that, Includes the following steps: Montmorillonite and a quaternary ammonium salt were combined to obtain a quaternary ammonium salt-modified montmorillonite composite. Then, the quaternary ammonium salt-modified montmorillonite composite was mixed with wood wax oil to obtain an anti-mildew coating liquid. Finally, the anti-mildew coating liquid was applied to the surface of bamboo, and after drying, antibacterial bamboo laminated timber reinforced with a montmorillonite composite antibacterial agent was obtained. The quaternary ammonium salt is either dodecyl dimethyl benzyl ammonium chloride or a mercapto quaternary ammonium salt modifier. The chemical structure of the mercapto quaternary ammonium salt modifier is as follows: 。 2. The preparation method of antibacterial bamboo laminated timber reinforced with montmorillonite composite antibacterial agent as described in claim 1, characterized in that, The method for compounding montmorillonite and quaternary ammonium salt is as follows: montmorillonite and quaternary ammonium salt are mixed in a solvent and then centrifuged. The solid obtained by centrifugation is washed, dried, and ground to obtain a quaternary ammonium salt modified montmorillonite composite. The mixing temperature is 60~70℃ and the time is 8~10h.

3. The preparation method of antibacterial bamboo laminated timber reinforced with montmorillonite composite antibacterial agent as described in claim 2, characterized in that, The mass ratio of montmorillonite to quaternary ammonium salt is 5:2.4~2.

8.

4. The preparation method of antibacterial bamboo laminated timber reinforced with montmorillonite composite antibacterial agent as described in claim 2, characterized in that, The montmorillonite mentioned is sodium-based montmorillonite.

5. The preparation method of antibacterial bamboo laminated timber reinforced with montmorillonite composite antibacterial agent as described in claim 4, characterized in that, The sodium-based montmorillonite has a cation exchange capacity of 145-150 mmol / 100g and an average particle size of 5-8 μm.

6. The method for preparing antibacterial bamboo laminated timber reinforced with montmorillonite composite antibacterial agent as described in claim 1, characterized in that, The mass ratio of the quaternary ammonium salt modified montmorillonite complex to wood wax oil is 3~4:95~97; the wood wax oil is composed of linseed oil, carnauba wax and soybean oil in a mass ratio of 6~7:3~5:1~2.

7. The method for preparing antibacterial bamboo laminated timber reinforced with montmorillonite composite antibacterial agent as described in claim 6, characterized in that, The method for mixing the quaternary ammonium salt-modified montmorillonite complex and wood wax oil is as follows: the quaternary ammonium salt-modified montmorillonite complex and wood wax oil are subjected to mechanical stirring and ultrasonic treatment sequentially; the mechanical stirring speed is 500~700 r / min, and the time is 30~50 min; the power density of the ultrasonic treatment is 0.5~0.6 W / cm³. 2 The time is 20-40 minutes.

8. The method for preparing antibacterial bamboo laminated timber reinforced with montmorillonite composite antibacterial agent as described in claim 1, characterized in that, The anti-mildew coating liquid is applied to the bamboo surface in two coats, with each coat consisting of 40-50 g / m². 2 .

9. The method for preparing antibacterial bamboo laminated timber reinforced with montmorillonite composite antibacterial agent as described in any one of claims 1-8, characterized in that, The preparation method of the mercapto quaternary ammonium salt modifier is as follows: pentaerythritol tetramercaptoacetate and 1-vinyl-3-butylimidazolium bromide are mixed and reacted in a solvent under the action of a photoinitiator and ultraviolet light, and then mixed and reacted with propenyltriethylammonium bromide under the action of a photoinitiator and ultraviolet light to obtain the mercapto quaternary ammonium salt modifier; the molar ratio of pentaerythritol tetramercaptoacetate, 1-vinyl-3-butylimidazolium bromide and propenyltriethylammonium bromide is 1:1:

1.

10. An antibacterial bamboo laminated timber prepared by the method of any one of claims 1-9 using montmorillonite composite antibacterial agent.

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