Moisture-heat aging resistant wood-plastic composite material and preparation method thereof

Abstract

The invention discloses a damp-heat aging-resistant wood-plastic composite material and a preparation method thereof, and belongs to the technical field of aging-resistant materials.The preparation method comprises the following steps that raw materials are processed and dried; modifying the salix psammophila fibers; step-by-step mixing and paving assembly are conducted; the main and auxiliary synergistic system of the anti-aging auxiliary agent is an antioxidant 1010 and DSTP; and hot-press molding: carrying out hot-press molding on the obtained plate blank to obtain the damp-heat aging resistant wood-plastic composite material. Maleic anhydride is adopted as an interface modifier of salix mongolica fibers and polylactic acid, the interface compatibility of the composite material is improved, the mechanical strength is improved, and meanwhile, an anti-aging auxiliary agent main-auxiliary synergistic system is constructed to provide excellent damp-heat aging resistance for the composite material. Test results show that the mechanical properties of the composite material before and after aging meet the corresponding national / industrial standard requirements.

Description

Technical Field

[0001] The present application relates to the technical field of aging-resistant materials, and in particular to a wood-plastic composite material resistant to moisture and heat aging and a preparation method thereof. Background Art

[0002] In recent years, with increasing attention to ecological conservation and deepening research in the field of materials, natural plant fiber / biodegradable plastic composites have gradually attracted widespread attention due to their low cost, environmental friendliness, excellent mechanical properties, strong plasticity, and good chemical stability. They show promising application prospects in fields such as architectural decoration, vehicle and shipbuilding, and aerospace.

[0003] However, because the main components of wood fiber, such as cellulose, hemicellulose, and lignin, contain a large number of hydroxyl groups, giving them strong chemical polarity, while biodegradable plastics are non-polar polymers, the interfacial compatibility of the two materials after composite is poor, greatly affecting the mechanical properties and service life of the composite material. Therefore, improving the interfacial compatibility between wood fiber and biodegradable plastics has been a research hotspot.

[0004] The long-term aging resistance of composite materials is becoming increasingly problematic, particularly in high-end sectors like aerospace and automotive manufacturing, where material aging can pose serious safety risks. Environmental factors such as ultraviolet light, heat and humidity, and oxidation can cause composite materials to experience reduced mechanical properties and surface degradation, severely impacting their service life and safety.

[0005] Therefore, how to develop a wood-plastic composite material with excellent aging resistance and heat-resistant aging and a preparation method thereof is a technical problem that those skilled in the art are in urgent need of solving. Summary of the Invention

[0006] In view of this, the present invention provides a wood-plastic composite material resistant to moisture and heat aging and a preparation method thereof.

[0007] A method for preparing a wood-plastic composite material resistant to moisture and heat aging comprises the following steps:

[0008] (1) Processing and drying of raw materials: peeling the Salix psammophila wood strips, crushing, sieving, and drying to obtain Salix psammophila fiber;

[0009] (2) Modification of Salix psammophila fiber: dissolving a coupling agent in a 95% by volume ethanol aqueous solution to obtain a coupling agent solution, spraying the coupling agent solution evenly on the Salix psammophila fiber obtained in step (1), and drying to obtain modified Salix psammophila fiber;

[0010] (3) Stepwise mixing and paving of the blank: the modified Salix psammophila fiber, polylactic acid and the main-auxiliary synergistic system of the anti-aging additive obtained in step (2) are divided into the first part and the second part of the material according to their mass, the modified Salix psammophila fiber, polylactic acid and the main-auxiliary synergistic system of the anti-aging additive of the first part are stirred and mixed, and then the modified Salix psammophila fiber, polylactic acid and the main-auxiliary synergistic system of the anti-aging additive of the remaining second part are added and stirred and mixed, the mixed material is placed in a mold for paving, the material is pressed, and it is allowed to stand for a period of time. After the shape of the material is fixed, a blank is obtained;

[0011] The main and auxiliary synergistic system of the above-mentioned anti-aging additives is antioxidant 1010 and DSTP;

[0012] (4) Hot pressing: hot pressing the slab obtained in step (3) to obtain the above-mentioned wet-heat-aging-resistant wood-plastic composite material.

[0013] Furthermore, in step (1), the safflower wood powder with a particle size of 40-60 mesh is screened and dried at a temperature of 70±2° C. until the moisture content of the safflower fiber is below 2%.

[0014] Beneficial effects of adopting this further technical solution: Research has shown that 40-60 mesh Salix psammophila wood flour can form a well-interwoven structure within the composite material, facilitating uniform matrix distribution and effective stress transfer, further enhancing mechanical properties. A drying temperature of 70±2°C ensures efficient drying of the modified wood flour without causing brittleness due to excessive temperatures. Drying to a moisture content below 2% ensures the wood flour retains a certain plasticity for hot pressing, while also preventing excessive moisture content from generating excessive water vapor during hot pressing, which could affect product quality.

[0015] Furthermore, in step (2), the coupling agent is maleic anhydride.

[0016] The beneficial effect of adopting the above-mentioned further technical solution is that the maleic anhydride coupling agent realizes interface strengthening between Salix psammophila and the polylactic acid matrix in the form of chemical bonding through esterification reaction and hydrogen bonding, which is beneficial to the improvement of mechanical strength.

[0017] Furthermore, in step (2), the concentration of the coupling agent solution is 20 wt%, and the amount of the coupling agent used is 2% of the mass of the Salix psammophila fiber.

[0018] The beneficial effects of adopting the above-mentioned further technical solution are as follows: adding the coupling agent in the form of a solution is conducive to the dispersion of the coupling agent between the substrates, thereby achieving a better interface modification effect; studies have shown that the interface modification effect is best when the coupling agent addition amount is 2%.

[0019] Furthermore, in step (2), the drying temperature is 70±2° C., and the modified Salix psammophila fiber is dried until the moisture content is below 2%.

[0020] The beneficial effects of this further technical solution include: a drying temperature of 70±2°C ensures efficient drying of the modified wood flour while preventing the wood flour from becoming brittle due to excessive temperatures. Drying to a moisture content below 2% ensures the wood flour retains a certain plasticity for hot pressing, while preventing excessive moisture content from generating excessive water vapor during hot pressing, which could affect product quality.

[0021] Furthermore, in step (3), the mass ratio of the modified tsavorite fiber to polylactic acid is 3:7, the added amount of the main-auxiliary synergistic system of anti-aging additives is 1-5% of the total mass of the modified tsavorite fiber and polylactic acid materials, and the mass ratio of antioxidant 1010 and DSTP is 3:2.

[0022] Beneficial effects of the aforementioned further technical solution: Research has shown that a mass ratio of 3:7 between Salix psammophila fiber and polylactic acid ensures excellent mechanical toughness in the composite material, fully maximizing the reinforcing effect of the Salix psammophila fiber. A synergistic system of anti-aging additives, added at a level of 1-5% of the total mass of the modified Salix psammophila fiber and polylactic acid, ensures excellent aging resistance in the composite material. A mass ratio of 3:2 between antioxidant 1010 and DSTP maximizes the synergistic effect of the two.

[0023] Furthermore, in step (3), the mass ratio of the first part and the second part of the material is 3:7, and the modified tsavorite fiber, polylactic acid and the main-auxiliary synergistic system of the anti-aging additive of the first part are stirred and mixed for 5-10 minutes at a stirring speed of 20-30 rpm, and then the remaining second part of the modified tsavorite fiber, polylactic acid and the main-auxiliary synergistic system of the anti-aging additive are added and stirred and mixed for 5-10 minutes at a stirring speed of 20-30 rpm.

[0024] The beneficial effect of adopting the above-mentioned further technical solution is that the "two-step" adding process can ensure more thorough mixing of the materials and further improve the uniformity of the dispersion of the material system.

[0025] Furthermore, in step (3), the pressure of the pressed material is 1 MPa and the standing time is 10 min.

[0026] The beneficial effects of adopting the above-mentioned further technical solution are as follows: the process can achieve the initial shaping of the slab material, the slab has sufficient initial strength, can ensure that the slab does not collapse, and meet the convenience of subsequent slab transportation, loading and other processes.

[0027] Furthermore, in step (4), the slab obtained in step (3) is hot-pressed at a temperature of 190° C., a hot-pressing pressure of 7 MPa, and a hot-pressing time of 7 minutes.

[0028] The beneficial effects of adopting the above further technical solution are as follows: the above process can achieve full forming of the material, and achieve the dual effects of good board quality and high production efficiency.

[0029] The present invention also provides a wood-plastic composite material resistant to moisture and heat aging prepared by the above method with a density of 0.80-1.20 g / cm 3 .

[0030] The present invention addresses the existing problem of insufficient mechanical strength due to poor interfacial compatibility in composite materials, and the inability of single-component anti-aging additives to impart excellent aging resistance to the composite. This invention utilizes Salix psammophila, a psammophyte shrub native to Inner Mongolia, and maleic anhydride as an interfacial modifier between Salix psammophila fiber and polylactic acid. This improves the interfacial compatibility and mechanical strength of the composite material, while also constructing a synergistic system of primary and secondary anti-aging additives to provide the composite with excellent resistance to wet-heat aging. Test results demonstrate that the mechanical properties of the composite material, both before and after aging, meet the requirements of relevant national / industry standards. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The figures are the bar graphs of static bending strength, elastic modulus and their retention rate at different ratios of 1010 / DSTP, where (a) is the bar graph of static bending strength, (b) is the bar graph of elastic modulus, (c) is the bar graph of static bending strength retention rate, and (d) is the bar graph of elastic modulus retention rate.

[0032] Figure 2 The figure (a) is a histogram of the impact strength and its retention rate at different ratios of 1010 / DSTP, where (b) is a histogram of the impact strength and (b) is a histogram of the impact strength retention rate.

[0033] Figure 3 Schematic diagram of the anti-aging mechanism of the 1010 / DSTP main-auxiliary system. DETAILED DESCRIPTION

[0034] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0035] Antioxidant 1010 was purchased from Shandong Junrui Pharmaceutical Technology Co., Ltd.

[0036] The antioxidant DSTP was purchased from Shanghai Yien Chemical Technology Co., Ltd.

[0037] The polylactic acid used in the present invention is powder, 100 mesh, molecular weight 5×10 4, density 1.24g / cm 3 .

[0038] Example 1

[0039] The preparation method of the wood-plastic composite material resistant to moisture and heat aging comprises the following steps:

[0040] (1) Processing and drying of raw materials: After peeling the bark of Salix psammophila, crush it, sieve it and take Salix psammophila powder with a particle size of 40-60 mesh, and dry it at a temperature of 70±2℃ until the moisture content of Salix psammophila fiber is below 2%;

[0041] (2) Modification of Salix psammophila fiber: dissolving maleic anhydride as a coupling agent in a 95% by volume ethanol aqueous solution to obtain a coupling agent solution with a concentration of 20 wt%, spraying the coupling agent solution evenly on the Salix psammophila fiber obtained in step (1), wherein the amount of the coupling agent is 2% of the mass of the Salix psammophila fiber, and drying the modified Salix psammophila fiber at a temperature of 70±2° C. until the moisture content of the modified Salix psammophila fiber is below 2%, thereby obtaining the modified Salix psammophila fiber;

[0042] (3) Step-by-step mixing and laying of the blank: the modified Salix psammophila fiber, polylactic acid and the main-auxiliary synergistic system of anti-aging additives obtained in step (2) are divided into the first part and the second part of the material according to their mass, and the mass ratio of the first part and the second part of the material is 3:7. The modified Salix psammophila fiber, polylactic acid and the main-auxiliary synergistic system of anti-aging additives of the first part are stirred and mixed for 8 minutes at a stirring speed of 25 rpm, and then the remaining modified Salix psammophila fiber, polylactic acid and the main-auxiliary synergistic system of anti-aging additives of the second part are added and stirred and mixed for 8 minutes at a stirring speed of 2. 5 revolutions per minute, the mass ratio of modified Salix psammophila fiber to polylactic acid is 3:7, the addition amount of the main and auxiliary synergistic system of anti-aging additives is 2.5% of the total mass of the Salix psammophila fiber and polylactic acid materials, the main and auxiliary synergistic system of anti-aging additives is antioxidant 1010 and DSTP, and the mass ratio of antioxidant 1010 and DSTP is 3:2. The mixed material is placed in a 200mm×200mm mold for paving, and the material is pressed to a thickness of 15mm. The pressing pressure of the material is 1MPa, and it is allowed to stand for 10min. After the material shape is fixed, a slab is obtained;

[0043] (4) Hot pressing: The slab obtained in step (3) was hot pressed at a temperature of 190°C, a hot pressing pressure of 7 MPa, and a hot pressing time of 7 min. The sample was trimmed to form a slab with a density of 1.0 g / cm 3 , a wood-plastic composite material resistant to moisture and heat aging was obtained with a thickness of 4 mm.

[0044] The composite material's static flexural strength and elastic modulus are 29.57 MPa and 2821 MPa, respectively, meeting the third-level requirements for static flexural strength and elastic modulus (≥23 MPa and ≥1800 MPa) for plain, unfoamed outdoor wood-plastic composite materials as specified in LY / T 3274-2021, "Grading of Wood-Plastic Composite Materials." It also meets the requirements of GB / T 24137-2009, "Wood-Plastic Decorative Panels" (≥20 MPa and ≥1880 MPa).

[0045] After hydrothermal aging at 60°C for 24 hours, the composite's static flexural strength and elastic modulus were 18.12 MPa and 1989 MPa, respectively, meeting the third-level requirements (≥18 MPa and ≥1400 MPa) for static flexural strength and elastic modulus of plain, unfoamed, outdoor wood-plastic composites after aging as specified in LY / T 3274-2021, "Grading of Wood-Plastic Composite Materials." The static flexural strength retention rate and mass loss rate were 61.28% and 6.55%, respectively.

[0046] Comparative Example 1

[0047] Compared with Example 1, except that the main-auxiliary synergistic system of anti-aging additives is not added, other steps and parameters are the same as those of Example 1.

[0048] Comparative Example 2

[0049] Compared with Example 1, except that the mass ratio of the main-auxiliary synergistic system of anti-aging additives, antioxidant 1010 and DSTP, is 3:1, other steps and parameters are the same as those in Example 1.

[0050] Comparative Example 3

[0051] Compared with Example 1, except that the mass ratio of the main-auxiliary synergistic system of anti-aging additives, antioxidant 1010 and DSTP, is 3:3, other steps and parameters are the same as those in Example 1.

[0052] Comparative Example 4

[0053] Compared with Example 1, except that the main and auxiliary synergistic system of anti-aging additives is replaced by antioxidant 1010, the added amount of antioxidant 1010 is 1.5% of the total mass of Salix fiber and polylactic acid material, and other steps and parameters are the same as Example 1.

[0054] Comparative Example 5

[0055] Compared with Example 1, except that the main and auxiliary synergistic system of anti-aging additives is replaced by antioxidant DSTP, the added amount of antioxidant DSTP is 1.5% of the total mass of Salix fiber and polylactic acid material, and other steps and parameters are the same as Example 1.

[0056] Comparative Example 6

[0057] Compared with Example 1, except that the main and auxiliary synergistic system of anti-aging additives is replaced by antioxidant 1010 and TiO2 nanoparticles, the mass ratio of antioxidant 1010 to TiO2 nanoparticles is 3:2, and other steps and parameters are the same as Example 1.

[0058] Comparative Example 7

[0059] Compared with Example 1, except that the main-auxiliary synergistic system of the anti-aging additive is replaced by antioxidant 1010 and ZnO powder, the mass ratio of antioxidant 1010 to ZnO powder is 3:1, and other steps and parameters are the same as Example 1.

[0060] The following experiments were conducted using Example 1 of the present invention and Comparative Examples 1-7.

[0061] 1. Effects of different main-auxiliary synergistic systems on the mechanical properties of composite materials

[0062] The effects of different ratios of the main-auxiliary synergistic system 1010 / DSTP on the static flexural strength, elastic modulus, and retention rate of the composite material after hydrothermal aging at 40°C for 10 hours are shown in Table 1. With the increase in the proportion of DSTP added, the static flexural strength, elastic modulus, and retention rate of the composite material before and after aging first increased and then decreased. The static flexural strength and elastic modulus of the composite material with an addition ratio of 3:2 in Example 1 before aging were 29.57MPa and 2821MPa, respectively, which were 5.68% and 2.68% higher than those of the blank sample in Example 1, respectively. After aging, the static flexural strength and elastic modulus were 26.28MPa and 2487MPa, respectively, which were 7.57% and 13.15% higher than those of the blank sample in Example 1. The retention rates of the static flexural strength and elastic modulus of the composite material were 88.87% and 88.16%, respectively, which were 5.13% and 5.81% higher than those of the blank sample.

[0063] Table 1 Mechanical properties and retention rates of wood-plastic composite materials of Example 1 and Comparative Examples 1-3

[0064]

[0065]

[0066] Note: * stands for mechanical property retention rate

[0067] Table 2 Mechanical properties and retention rates of wood plastic composite materials of comparative examples 4-7

[0068]

[0069] Note: * stands for mechanical property retention rate

[0070] During hydrothermal degradation, the PLA matrix gradually decomposes and produces free radicals, which further trigger the degradation of the composite material. As the proportion of the anti-aging additive DSTP increases, 1010 captures the free radicals generated during the hydrothermal degradation process in the system. The intermediate hydroperoxides produced during the hydrothermal degradation process are also captured by DSTP, preventing the free radical reaction of the PLA matrix during hydrothermal degradation. The two create a synergistic anti-aging effect. Their combined effects on the composite material reduce the degradation and cross-linking reactions of the polymer molecular chains, thereby improving the composite's static flexural strength, elastic modulus, and retention rate. Figure 1 The bar graphs of static bending strength, elastic modulus and retention rate of different ratios of 1010 / DSTP are shown as follows: Figure 1 As shown in Figures (a)-(d), when the ratio is 3:2, 1010 captures free radicals at a relatively fast rate, quickly suppressing the initiation of oxidation reactions. DSTP then decomposes the generated hydroperoxides, preventing them from initiating further oxidation reactions. The combined effect of the two additives effectively inhibits the thermal oxidative degradation of polymer materials and improves the composite's static flexural strength, elastic modulus, and retention. When the ratio is 3:3, the two additives have similar concentrations in the system. Both need to compete for free radicals and hydroperoxides to exert their antioxidant function. In their reactions with free radicals and hydroperoxides, they may compete for active sites, thereby affecting their static flexural strength, elastic modulus, and retention.

[0071] Figure 2 The following is a bar graph showing the impact strength and retention rate changes at different ratios of 1010 / DSTP: Figure 2 As shown in Figures (a) and (b), as the amount of DSTP added increases, the impact strength of the composite material increases first and then decreases before and after aging. The impact strength of the composite material with an addition ratio of 3:2 in Example 1 is 3.829KJ / m 2 , which is 5.45% higher than that of the blank sample 1, and the impact strength after aging is reduced to 3.378KJ / m 2 , which is 13.47% higher than that of the blank sample in Comparative Example 1. The impact strength retention rate of the composite material is 88.23%, which is 6.24% higher than that of the blank sample in Comparative Example 1.

[0072] As the addition ratio of the aging-resistant additive DSTP increases, the synergistic effect of 1010 / DSTP reduces internal defects and stress concentration points in the material to a certain extent, improving the composite's impact strength and retention. At a ratio of 3:2, 1010 / DSTP can work together to reduce internal defects and stress concentration points, enhancing the material's toughness and impact resistance. The synergistic effect of the two is more effective, resulting in a significant improvement in impact strength and retention. At a ratio of 3:3, the rapid reaction of 1010 rapidly reduces the number of free radicals in the system, resulting in a lack of substrate for DSTP's subsequent decomposition of hydroperoxides. This leads to the accumulation of oxidation products within the material, resulting in a decrease in impact strength and retention.

[0073] (2) Analysis of the aging resistance mechanism of the main and auxiliary synergistic system of aging resistance

[0074] The anti-aging mechanism of anti-aging additive 1010 / DSTP is as follows: Figure 3 As shown. The phenolic hydroxyl group (-OH) in the anti-aging agent 1010 molecule can provide hydrogen atoms (H · ) to free radicals (such as PO · POOH · ), thereby terminating the oxidation reaction of the molecular chain; the thiodipropionate (-S-CH2-CH2-COOR) in the anti-aging auxiliary agent DSTP can decompose hydroperoxide (ROOH) into stable alcohol (ROH), preventing it from breaking down into free radicals, and assisting the anti-aging main agent 1010 in delaying the oxidative degradation process of the composite material by decomposing the intermediate product hydroperoxide in the oxidation process.

[0075] In summary: The performance is optimal when the 1010 / DSTP ratio is 3:2. After aging, the static bending strength is 26.28MPa, the elastic modulus is 2487MPa, and the impact strength is 3.378KJ / m 2 The retention rates were 88.87%, 88.16% and 88.23% respectively, showing the best comprehensive performance. 1010 captures free radicals and DSTP decomposes hydroperoxides to form a dual antioxidant network.

[0076] As shown in Table 2, the performance is optimal when the 1010 / TiO2 ratio is 3:2, with an elastic modulus retention rate of 86.76%, but the impact performance improvement is limited. The physical barrier of TiO2 complements the chemical antioxidant effect of 1010, but the dispersion of nanoparticles limits the toughening effect. The performance is optimal when the 1010 / ZnO ratio is 3:1, with an impact strength retention rate of 85.78%, slightly lower than that of the 1010 / DSTP system. ZnO decomposition intermediates assist 1010, but competition for active sites reduces the synergistic efficiency. Through single-factor and compound system studies, it is clear that 1010 / DSTP at a ratio of 3:2 is the optimal main-auxiliary synergistic system of aging-resistant additives. Its synergistic antioxidant mechanism and interface enhancement effect significantly improve the aging resistance of composite materials, providing a theoretical basis for subsequent aging mechanism research and engineering applications.

[0077] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a wood-plastic composite material resistant to moisture and heat aging, characterized in that: The following steps are involved: (1) Processing and drying of raw materials: peeling the Salix psammophila wood strips, crushing, sieving, and drying to obtain Salix psammophila fiber; (2) Modification of Salix psammophila fiber: dissolving a coupling agent in a 95% by volume ethanol aqueous solution to obtain a coupling agent solution, spraying the coupling agent solution evenly on the Salix psammophila fiber obtained in step (1), and drying to obtain modified Salix psammophila fiber; (3) Stepwise mixing and paving of the blank: the modified Salix psammophila fiber, polylactic acid and the main-auxiliary synergistic system of the anti-aging additive obtained in step (2) are divided into the first part and the second part of the material according to their mass, the modified Salix psammophila fiber, polylactic acid and the main-auxiliary synergistic system of the anti-aging additive of the first part are stirred and mixed, and then the modified Salix psammophila fiber, polylactic acid and the main-auxiliary synergistic system of the anti-aging additive of the remaining second part are added and stirred and mixed, the mixed material is placed in a mold for paving, the material is pressed, and it is allowed to stand for a period of time. After the shape of the material is fixed, a blank is obtained; The main and auxiliary synergistic system of anti-aging additives is antioxidant 1010 and DSTP; (4) Hot pressing: hot pressing the blank obtained in step (3) to obtain the wet-heat aging resistant wood-plastic composite material.

2. The method for preparing a wood-plastic composite material resistant to moisture and heat aging according to claim 1, characterized in that: In step (1), the safflower wood powder with a particle size of 40-60 mesh is screened and dried at a temperature of 70±2° C. until the moisture content of the safflower fiber is below 2%.

3. The method for preparing a wood-plastic composite material resistant to moisture and heat aging according to claim 1, characterized in that: In step (2), the coupling agent is maleic anhydride.

4. The method for preparing a wood-plastic composite material resistant to moisture and heat aging according to claim 1, characterized in that: In step (2), the concentration of the coupling agent solution is 20 wt %, and the amount of the coupling agent used is 2% of the mass of the Salix psammophila fiber.

5. The method for preparing a wood-plastic composite material resistant to moisture and heat aging according to claim 1, characterized in that: In step (2), the drying temperature is 70±2° C., and the modified Salix psammophila fiber is dried until the moisture content is below 2%.

6. The method for preparing a wood-plastic composite material resistant to moisture and heat aging according to claim 1, characterized in that: In step (3), the mass ratio of the modified salix fiber to polylactic acid is 3:7, the added amount of the main-auxiliary synergistic system of anti-aging additives is 1-5% of the total mass of the modified salix fiber and polylactic acid materials, and the mass ratio of antioxidant 1010 and DSTP is 3:

2.

7. The method for preparing a wood-plastic composite material resistant to moisture and heat aging according to claim 1, characterized in that: In step (3), the mass ratio of the first part and the second part of the material is 3:

7. The modified tsavorite fiber, polylactic acid and the main-auxiliary synergistic system of the anti-aging additive of the first part are stirred and mixed for 5-10 minutes at a stirring speed of 20-30 rpm. Then, the remaining second part of the modified tsavorite fiber, polylactic acid and the main-auxiliary synergistic system of the anti-aging additive are added and stirred for 5-10 minutes at a stirring speed of 20-30 rpm.

8. The method for preparing a wood-plastic composite material resistant to moisture and heat aging according to claim 1, characterized in that: In step (3), the pressure of the pressed material is 1 MPa and the standing time is 10 min.

9. The method for preparing a wood-plastic composite material resistant to moisture and heat aging according to claim 1, characterized in that: In step (4), the slab obtained in step (3) is hot-pressed at a temperature of 190° C., a hot-pressing pressure of 7 MPa, and a hot-pressing time of 7 minutes.

10. A wood-plastic composite material resistant to moisture and heat aging prepared by the method according to any one of claims 1 to 9, characterized in that: Density is 0.80-1.20g / cm 3 .

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