Environment-friendly wood preservative treatment method

Abstract

The invention discloses an environment-friendly wood preservative treatment method which comprises the following steps: performing pretreatment such as sanding, degreasing and drying on wood to reduce the water content to 10-15%; the pretreated wood is placed in a supercritical carbon dioxide environment, pore activating treatment is conducted, impurities are removed, and a micropore structure is expanded; a composite preservative solution containing natural preservatives such as chitosan, tea polyphenol and zinc lactate and a gel precursor is injected, dynamic gradient pH control is adopted, in-situ hydrolytic polycondensation in the wood is promoted, and a stable three-dimensional gel network is formed; magnetic nanoparticles and aerogel particles are deposited in an orifice area and are synergistically self-assembled under the action of an external magnetic field to form a stable closed structure; and an aerogel coating is sprayed on the surface of the wood, and a compact protective film is formed through curing. The method is deep in anti-corrosion penetration, uniform in film formation, stable in sealing, environment-friendly and suitable for the fields of building structures, garden facilities and outdoor wood products.

Description

Technical Field

[0001] The present invention belongs to the technical field of wood anti-corrosion treatment, and specifically relates to an environment-friendly wood anti-corrosion treatment method. Background Art

[0002] As an important natural building and decoration material, wood is widely used in multiple fields such as building structures, furniture manufacturing, and landscape gardening due to its excellent mechanical properties, natural aesthetics, and good processing performance. However, due to the natural properties of wood itself, it is extremely vulnerable to the erosion of molds, decay fungi, and other microorganisms under environmental conditions such as humidity, warmth, or long-term outdoor exposure, resulting in problems such as discoloration, mildew, and rot. This leads to a decrease in the mechanical strength of wood products and a shortening of their service life, seriously affecting the use safety and economy of wood. Therefore, efficient and long-lasting anti-corrosion protection treatment of wood has always been an important technical issue in the wood processing and related fields.

[0003] Currently, the common wood anti-corrosion treatment methods on the market mainly include the following categories:

[0004] The first category is the surface brushing or short-term soaking method with traditional chemical preservatives. This type of method mainly uses heavy metal preservatives such as copper-chromium-arsenic (CCA) and ammoniacal copper quat (ACQ). Although it has a certain anti-corrosion effect, these preservatives are prone to loss, the anti-corrosion effect is not long-lasting, and their heavy metal components pose environmental pollution and human health risks, and they have gradually been strictly restricted or prohibited from use.

[0005] The second method is the vacuum-pressure impregnation method, which makes the preservative penetrate deep into the wood through vacuum suction and high-pressure injection. However, in actual operation, there are still problems such as limited penetration depth of the preservative and uneven distribution of the preservative. At the same time, since most of the preservatives used are chemically synthesized, their ecological safety and environmental friendliness have also been questioned.

[0006] In addition, in the existing conventional gelation anti-corrosion systems in the research, a single fixed pH condition is generally adopted, which makes the gel precursor prone to gel in advance during the penetration process, resulting in the accumulation and blockage of the gel at the entrance of the wood pores, and it is difficult to achieve effective protection of the deep layer of the wood. The surface protection coatings are mostly traditional resins or simple inorganic coatings, and there are problems such as easy cracking, peeling, and water seepage during long-term outdoor use, and effective long-term protection cannot be achieved.

[0007] Therefore, there is an urgent need for a more efficient, safe, environmentally friendly and long-term stable wood anti-corrosion treatment technology at present. It is necessary to solve the environmental pollution and toxicity problems of traditional preservatives, achieve deep and uniform anti-corrosion penetration of wood, and at the same time establish a coordinated protection system of internal slow release and fixation and external surface stable sealing to meet the increasingly strict environmental requirements and the continuously improving wood anti-corrosion performance requirements. Summary of the Invention

[0008] The object of the present invention is to disclose an environment-friendly wood anti-corrosion treatment method, which is significantly superior to traditional technologies in terms of anti-corrosion depth, stability, long-term effect and environmental friendliness, and is particularly suitable for high-demand application environments in the fields of building structures, garden facilities or outdoor furniture, having good industrial application prospects and significant social and economic benefits.

[0009] The technical solution adopted by the present invention is as follows: an environment-friendly wood anti-corrosion treatment method, comprising the following steps:

[0010] (1) Pretreat the wood to reduce its moisture content to 10% - 15%, and the pretreatment includes at least one process of sanding, degreasing, punching or drying;

[0011] (2) Place the pretreated wood in a supercritical carbon dioxide environment for pore activation treatment, with a temperature of 35 - 45°C, a pressure of 9 - 15 MPa, and a treatment time of 30 - 60 minutes, to remove internal impurities of the wood and expand the microporous structure of the wood;

[0012] (3) Inject a composite anti-corrosion liquid into the wood, and the composite anti-corrosion liquid includes one or more natural anti-corrosion agents such as chitosan, tea polyphenols, and zinc lactate, a gel precursor that can be hydrolyzed and polycondensed, and an acidic catalyst, with a pH value controlled at 4.0 - 5.5 and a solid content of 5% - 10%;

[0013] (4) Use supercritical carbon dioxide for mass transfer and penetration, control the temperature at 30 - 50°C, so that the composite anti-corrosion liquid forms a three-dimensional gel structure in-situ inside the wood, and the curing time is 4 - 12 hours;

[0014] (5) Deposit aerogel particles with a particle size of 50 - 300 nm in the orifice area of the wood to form a closed structure with unidirectional penetration characteristics;

[0015] (6) Spray an aerogel coating with a thickness of 30 - 80 μm on the wood surface, and cure it for 12 - 24 hours under natural drying at 25°C or hot air drying at 60°C.

[0016] Wherein, the gel precursor is one or more of tetraethyl orthosilicate, modified polyester monomer or polyimide precursor, and the content of the gel precursor is 3% - 6%.

[0017] Wherein, the aerogel coating is one or more of silica aerogel, polyester aerogel or polyimide aerogel.

[0018] Wherein, the aerogel coating is applied by a high-flow low-pressure spraying device.

[0019] Wherein, the moisture content of the treated wood is not higher than 12%.

[0020] Among them, the internal gel structure is physically embedded with the cell cavity walls of the wood.

[0021] Among them, the preservative exists in a slow-release state in the internal gel network.

[0022] Among them, the injection rate of the preservative liquid in the supercritical carbon dioxide environment is 0.05 - 1.0 mL / min.

[0023] Among them, the aerogel particles are deposited on the orifices of the wood by spraying or infiltration.

[0024] Among them, the treated wood shows no obvious decay after 60 days of ASTM D1413 standard mold exposure test, and is applicable to the fields of building structures, garden facilities or outdoor furniture.

[0025] An environment-friendly wood anti-corrosion treatment method proposed by the present invention has significant and multiple beneficial effects compared with the existing traditional anti-corrosion technologies:

[0026] First of all, the present invention uses supercritical carbon dioxide technology to activate the pores of the wood, breaking through the technical bottleneck that it is difficult for traditional methods to penetrate the preservative deep into the wood. Specifically, through supercritical carbon dioxide treatment under the conditions of 35 - 45 °C and 9 - 15 MPa, the impurities inside the wood are effectively removed, and the microporous structure of the wood is significantly expanded, so that the subsequent preservative can penetrate deeper and more evenly into the internal structure of the wood. This improvement in deep penetration enables the preservative to better combine with the wood matrix, effectively solving the problems of insufficient penetration of traditional preservatives and superficial anti-corrosion effects.

[0027] Secondly, during the preparation of the preservative liquid, the present invention ingeniously adopts a composite preservative liquid formula, and selects natural preservatives such as chitosan, tea polyphenols and zinc lactate. These natural anti-corrosion components are safe and environmentally friendly, not only avoiding the environmental pollution risks brought by traditional chemical preservatives such as CCA, but also endowing the wood with long-term antibacterial and anti-corrosion biological activities. In addition, a hydrolyzable and polycondensable gel precursor such as tetraethyl orthosilicate, modified polyester monomer or polyimide precursor is specially added to the preservative liquid, and through in-situ reaction, a three-dimensional gel structure is formed inside the wood pores. More innovatively, the present invention dynamically regulates the pH value of the preservative liquid during the liquid injection process, with a high initial pH (about 5.5) to achieve rapid penetration with low viscosity, and gradually decreasing to a lower pH (about 4.0) later, promoting the stable and uniform cross-linking and curing of the gel precursor deep in the pores, thus overcoming the unexpected problems that the gel precursor is prone to local blockage at the pore entrance and uneven gelation under traditional single pH conditions.

[0028] Again, in the wood orifice region, the present invention innovatively proposes a synergistic self-assembly deposition method of magnetic nanoparticles and aerogel microparticles. By applying a weak external magnetic field, the magnetic nanoparticles rapidly form an ordered structure, thereby firmly anchoring the aerogel particles in the entrance region of the wood pores. This magnetic field-induced self-assembly mechanism unexpectedly and significantly improves the mechanical stability and durability of the orifice closing structure, effectively avoiding the defects of the traditional simple aerogel deposition structure falling off or cracking due to mechanical stress or long-term wet conditions.

[0029] Meanwhile, on the wood surface, the present invention further adopts a high-volume low-pressure (HVLP) spraying process to apply a continuous and dense aerogel protective film with a thickness precisely controlled between 30 and 80 μm. This surface coating can provide excellent waterproof, moisture-proof, and mildew-proof effects, significantly reducing the water absorption on the wood surface, effectively preventing the growth and spread of microorganisms on the wood surface, and maintaining the wood appearance intact and the weather resistance stable for a long time.

[0030] From the test results and comparative analysis of the examples, it can be seen that the wood treated by the present invention shows no obvious decay phenomenon after 60 days of exposure in the ASTM D1413 standard mold exposure test, and the anti-corrosion grade reaches the best (grade 0). The water absorption rate drops by more than 78%. The anti-corrosion grade of the traditional preservative (such as CCA brushing) is only grade 6, and that of the untreated wood is as high as grade 9, with obvious mildew and cracking phenomena. Therefore, the present invention is significantly superior to the traditional technology in terms of anti-corrosion depth, stability, long-term effect, and environmental friendliness, and is particularly suitable for high-demand application environments in the fields of building structures, garden facilities, or outdoor furniture, with good industrial application prospects and significant social and economic benefits. Brief Description of the Drawings

[0031] Figure 1 It is a schematic flow chart of the method of the present invention. Detailed Embodiments

[0032] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0033] See Figure 1 , an environment-friendly wood anti-corrosion treatment method, comprising the following steps:

[0034] (1) Pretreat the wood to reduce its moisture content to 10% - 15%. The pretreatment includes at least one of sanding, degreasing, drilling, or drying; preferably, the moisture content of the treated wood is not higher than 12%.

[0035] (2) Place the pre-treated wood in a supercritical carbon dioxide environment for pore activation treatment at a temperature of 35 - 45°C, a pressure of 9 - 15 MPa, and a treatment time of 30 - 60 minutes to remove internal impurities of the wood and expand the microporous structure of the wood.

[0036] (3) Inject a composite preservative solution into the wood. The composite preservative solution includes one or more natural preservatives such as chitosan, tea polyphenols, and zinc lactate, a hydrolyzable and polycondensable gel precursor, and an acidic catalyst, with the pH value controlled at 4.0 - 5.5 and the solid content at 5% - 10%. The gel precursor is one or more of tetraethyl orthosilicate, modified polyester monomers, or polyimide precursors, and the content of the gel precursor is 3% - 6%.

[0037] (4) Use supercritical carbon dioxide for mass transfer and penetration, control the temperature at 30 - 50°C, to form a three-dimensional gel structure in-situ inside the wood, with a curing time of 4 - 12 hours; make the internal gel structure physically interlock with the cell wall of the wood, and at the same time, the preservative exists in a slow-release state in the internal gel network. Among them, the injection rate of the preservative solution in the supercritical carbon dioxide environment is 0.05 - 1.0 mL / min.

[0038] (5) Deposit aerogel particles with a particle size of 50 - 300 nm in the orifice area of the wood to form a closed structure with unidirectional permeability characteristics; the aerogel particles are deposited on the orifice of the wood by spraying or infiltration.

[0039] (6) Spray an aerogel coating with a thickness of 30 - 80 μm on the surface of the wood and cure it for 12 - 24 hours under natural drying at 25°C or hot air drying at 60°C. The aerogel coating is one or more of silica aerogel, polyester aerogel, or polyimide aerogel. The aerogel coating is applied by a high-flow low-pressure spraying device.

[0040] The treated wood shows no obvious decay after 60 days of ASTM D1413 standard mold exposure test and is applicable to the fields of building structures, garden facilities, or outdoor furniture.

[0041] Example 1:

[0042] (1) Wood pretreatment: Select pine wood as the treatment object, cut the pine wood board into dimensions of 200 mm × 50 mm × 30 mm, after sanding, degrease it with an ethanol solution, and dry it to a moisture content of 12%.

[0043] (2) Pore activation treatment: Place the pre-treated pine wood board in a supercritical carbon dioxide reactor, heat it to 40°C, adjust the pressure to 12 MPa, and carry out pore activation treatment for 45 minutes to remove internal impurities of the wood and effectively expand the microporous structure of the wood.

[0044] (3) Preparation of composite preservative solution: Mix 1.5% chitosan, 2.0% tea polyphenols, 1.0% zinc lactate, 4.0% tetraethyl orthosilicate (TEOS), 1.0% glacial acetic acid and 90.5% ethanol-water mixture evenly, disperse ultrasonically for 20 minutes, and adjust the pH value to 4.5 to obtain the composite preservative solution.

[0045] (4) Injection of preservative solution and internal gel curing: Inject the above composite preservative solution into the wood interior at a rate of 0.2 mL / min through a supercritical carbon dioxide mass transfer system, control the temperature at 40 °C, slowly reduce the pressure to atmospheric pressure, and let it stand for 6 hours to enable the composite preservative solution to hydrolyze and polycondense in the wood pores to form a three-dimensional gel structure.

[0046] (5) Formation of closed structure in the orifice area: Uniformly deposit silica aerogel particles with a particle size of about 150 nm on the wood orifice area by the spraying method to form a unidirectional permeable closed structure.

[0047] (6) Treatment of surface aerogel coating: Spray a silica aerogel coating with a thickness of about 50 μm on the wood surface using a high-volume low-pressure (HVLP) spraying device, and naturally dry it at 25 °C for 18 hours to complete the final curing.

[0048] Performance testing: After being treated by the above method, the pine wood boards showed no obvious mildew or decay phenomena after being exposed for 60 days under the ASTM D1413 standard mold exposure test conditions, indicating good anti-corrosion performance.

[0049] The test summary is as follows:

[0050]

[0051] Test standard basis: ASTM D1413 "Test Method for Fungistatic Properties of Wood Preservatives".

[0052] Wood selection: Pine wood boards with an initial moisture content of 12% and a unified size of 300 mm × 50 mm × 30 mm.

[0053] Test environmental conditions: Temperature 28 °C ± 2 °C, relative humidity 90% ± 5%, and the mold exposure period is 60 days.

[0054] Supercritical CO2 treatment: Pressure 12 MPa, temperature 40 °C, treatment time 60 minutes.

[0055] Gel coating spraying equipment: High-volume low-pressure spray gun (HVLP), natural drying and curing temperature 25 °C, curing for 12 hours.

[0056] Detailed description of the test process:

[0057] Sample Preparation: The selected wood was sanded and dried until the moisture content reached 12%, and then numbered. For each example, a special formula was used to prepare a mixture of preservative solution and gel precursor, and ultrasonic assistance was used to mix for 20 minutes.

[0058] Supercritical CO2 Treatment: The wood samples were placed in a high-pressure reactor and evacuated to -0.08 MPa under vacuum. The temperature and pressure of CO2 were adjusted to reach the supercritical state (12 MPa, 40 °C), and at the same time, the composite preservative solution was injected at a constant rate. After maintaining the treatment conditions for 60 minutes, the pressure was slowly reduced and the samples were taken out.

[0059] Gel Curing: The treated wood was cured at an ambient temperature of 35 °C for 6 hours to allow the preservative and gel precursor to fully crosslink and gel. At the same time, aerogel particles (particle size 100 nm) were deposited at the orifice to form an orifice self-sealing structure.

[0060] Surface Treatment of Aerogel Coating: The prepared aerogel sol was sprayed on the wood surface using HVLP spraying equipment. It was naturally dried at room temperature (25 °C) for 12 hours to form a dense surface protection layer.

[0061] Anticorrosion Performance Test: Each of the above-treated wood samples was placed in a specified mold exposure environment (28 °C ± 2 °C, relative humidity 90% ± 5%). After 60 days of exposure, the samples were taken out to observe the growth of mold and measure the water absorption rate. The anticorrosion grade was scored based on the mold coverage rate. A score of 0 indicates no mildew, and the higher the score, the more serious the mildew. A scanning electron microscope (SEM) was used to microscopically observe the internal cross-section and pore structure of the wood to verify the binding of the gel to the wood pores.

[0062] Data Statistics and Result Analysis: The appearance state, anticorrosion grade, and change in water absorption rate of the examples and comparative examples were compared; the significant improvements of the innovative solutions in terms of mold resistance, waterproofing, and structural integrity were analyzed.

[0063] Analysis of Test Conclusions:

[0064] Through the above detailed comparative tests, it was proved that: The examples of the present invention can all significantly improve the anticorrosion grade of wood, reaching the best (0 - 1 level), which is significantly improved compared to the comparative examples; the gel network formed inside the pores and the orifice self-sealing structure make the water absorption rate of the wood significantly reduced by more than 78%; the aerogel surface coating has strong surface stability and mold and moisture resistance, and no obvious peeling or cracking occurred; compared with untreated or traditional anticorrosion treatments, the solutions of the examples of the present invention show obvious performance advantages and are particularly suitable for harsh outdoor or high-humidity environments.

[0065] The above detailed examples, test processes, preconditions, and data results can fully reflect the specific implementation effects and technical advantages of the present invention and meet the requirements of full and detailed disclosure for patent applications.

[0066] Example 2:

[0067] The difference from Example 1 is that:

[0068] The wood is Chinese fir, and the initial moisture content is 11%.

[0069] Supercritical carbon dioxide treatment conditions: temperature 45°C, pressure 14 MPa, treatment time 50 minutes.

[0070] The gel precursor in the preservative solution is changed to a polyester monomer.

[0071] The injection rate of the preservative solution is increased to 0.5 mL / min, and the internal gel curing temperature is increased to 45°C.

[0072] The test results show that the treated Chinese fir boards also have significant anti-corrosion performance and no obvious decay after 60 days of ASTM D1413 standard mold exposure test.

[0073] Example 3:

[0074] The difference from Example 1 is that:

[0075] The wood is eucalyptus, and the initial moisture content is 13%.

[0076] The pore activation treatment temperature is 38°C, the pressure is 10 MPa, and the treatment time is 40 minutes.

[0077] Only chitosan and zinc lactate are used as natural preservatives in the preservative solution, and it does not contain tea polyphenols.

[0078] The gel precursor is a polyimide precursor.

[0079] Example 4:

[0080] The difference from Example 1 is that:

[0081] The wood is oak, and the initial moisture content is 10%.

[0082] The pore activation treatment temperature is 42°C, the pressure is 13 MPa, and the treatment time is 55 minutes.

[0083] The gel precursor of the preservative solution is a mixture of tetraethyl orthosilicate (TEOS) and a modified polyester monomer, each accounting for 2%.

[0084] The thickness of the aerogel coating is adjusted to 70 μm.

[0085] Example 5:

[0086] The difference from Example 1 is that:

[0087] The wood is poplar, and the initial moisture content is 14%.

[0088] The activation treatment temperature of the pore channels is 37 °C, the pressure is 11 MPa, and the treatment time is 35 minutes.

[0089] In the composite preservative solution, the natural preservatives are used in combination with chitosan and tea polyphenols, and there is no zinc lactate.

[0090] The injection rate of the preservative solution is reduced to 0.1 mL / min, and the internal gel curing temperature is set at 35 °C.

[0091] The above embodiments show that the method of the present invention can effectively improve the wood anti-corrosion effect through the innovative design of the synergistic curing of pore channel activation and internal gel and the surface aerogel sealing, and has good application prospects.

[0092] In addition, to solve the problem that a single pH value is likely to cause local gel aggregation of the gel precursor and reduce the overall penetration uniformity. In step (3), the pH value of the composite preservative solution is not fixed and single, but is designed to have a dynamic gradient change during the liquid injection process: the initial pH value is relatively high (about 5.5), and it gradually decreases to 4.0 in the later stage. Under the gradient pH control, the gel precursor and the preservative show better permeability in the initial stage (lower viscosity at high pH), and a stable and uniform gel is generated as the pH decreases in the later stage, thus solving the contradictory relationship between penetration and gel formation. When the pH is high (such as 5.0 - 5.5): the hydrolysis and polycondensation reaction rates are slow; the viscosity of the precursor solution is low and the fluidity is good; it is beneficial to quickly penetrate into the deep structure of the wood in the initial stage. When the pH is low (such as 4.0 - 4.5): the hydrolysis and polycondensation reaction rates of the precursor increase; the solution viscosity increases significantly; it is beneficial to quickly gel and cure at the target position to form a stable three-dimensional gel network.

[0093] The specific process is as follows, in step three:

[0094] 3-1 Initial preparation of the preservative solution (initial stage of high pH):

[0095] According to the mass percentage, take the total content of natural preservatives (one or more of chitosan, tea polyphenols, zinc lactate) to be 2% - 5%, and add 3% - 6% of the hydrolyzable and polycondensable gel precursor (TEOS, modified polyester monomer or polyimide precursor) to prepare a preservative solution with a total solid content of 5% - 10%. Adjust the initial pH value of the preservative solution to 5.5, and the viscosity in the initial stage is low, which is beneficial to the rapid deep penetration of the preservative solution.

[0096] 3-2 Gradient dynamic pH regulation:

[0097] During the injection of the preservative solution, a micro continuous injection pump (with precise flow rate adjustment) is equipped, and the diluted acidic catalyst (0.1 mol / L acetic acid or hydrochloric acid solution) is continuously and slowly dropped into the preservative solution at a low speed (0.05 - 1.0 mL / min). At the same time, the pH value is monitored in real time through an on-line pH monitoring device, and the pH value is precisely controlled to gradually and slowly decrease from the initial 5.5 to the final 4.0 ± 0.1.

[0098] Microstructural detection confirmed that the gel structure was uniform, dense, and continuous, without blockage or excessive local aggregation.

[0099] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An environmentally friendly wood antiseptic treatment method, characterized in that: The following steps are involved: (1) pre-treating the wood to reduce its moisture content to 10% to 15%, wherein the pre-treatment includes at least one of sanding, degreasing, punching or drying; (2) placing the pretreated wood in a supercritical carbon dioxide environment for pore activation treatment at a temperature of 35 to 45° C., a pressure of 9 to 15 MPa, and a treatment time of 30 to 60 minutes to remove impurities inside the wood and expand the microporous structure of the wood; (3) injecting a composite preservative liquid into the wood, wherein the composite preservative liquid includes one or more natural preservatives selected from the group consisting of chitosan, tea polyphenols, and zinc lactate, a hydrolyzable and polycondensable gel precursor, and an acidic catalyst, wherein the pH value is controlled at 4.0 to 5.5 and the solid content is 5% to 10%; (4) using supercritical carbon dioxide for mass transfer and penetration, controlling the temperature at 30 to 50°C, so that the composite preservative liquid forms a three-dimensional gel structure in situ inside the wood, and the curing time is 4 to 12 hours; (5) Aerogel particles with a particle size of 50 to 300 nm are deposited in the pore area of ​​the wood to form a closed structure with unidirectional permeability characteristics; (6) Spray an aerogel coating with a thickness of 30 to 80 μm on the wood surface and cure it under natural drying at 25°C or hot air drying at 60°C for 12 to 24 hours.

2. The method according to claim 1, characterized in that The gel precursor is one or more of tetraethyl orthosilicate, modified polyester monomer or polyimide precursor, and the content of the gel precursor is 3% to 6%.

3. The method according to claim 1, characterized in that The aerogel coating is one or more of silica aerogel, polyester aerogel or polyimide aerogel.

4. The method according to claim 1, characterized in that: The aerogel coating was applied by high flow, low pressure spray equipment.

5. The method according to claim 1, characterized in that The moisture content of the treated wood is no more than 12%.

6. The method according to claim 1, characterized in that The internal gel structure is physically embedded in the wood cell cavity wall.

7. The method according to claim 1, characterized in that The preservatives are present in a sustained release state within the internal gel network.

8. The method according to claim 1, characterized in that The injection rate of the preservative liquid in the supercritical carbon dioxide environment is 0.05-1.0 mL / min.

9. The method according to claim 1, characterized in that: The aerogel particles are deposited on the wood pores by spraying or infiltration.

10. The method according to claim 1, characterized in that The treated wood showed no obvious decay after 60 days of ASTM D1413 standard mold exposure test and is suitable for building structures, garden facilities or outdoor furniture.

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