Corrosion-resistant hydrolysis-resistant toughened polyamide composite material and preparation method thereof

Abstract

The invention belongs to the field of polyamide composite materials, and particularly provides a corrosion-resistant hydrolysis-resistant toughened polyamide composite material and a preparation method thereof. The composite material is prepared by mixing the following raw materials in parts by mass: 50-60 parts of polyhexamethylene adipamide, 10-20 parts of polycaprolactam, 5-8 parts of composite modified particles, 2-3 parts of a compatilizer, 0.5-1.5 parts of an antioxidant and 1-3 parts of a heat-resistant agent, the composite modified particles are obtained by sintering raw materials including alpha-aluminum oxide, copper oxide, cuprous oxide, silicon carbide, zirconium hydrogen phosphate and sodium hypophosphite and then modifying the raw materials through fluoroalkoxy silane. The composite modified particles are used as an adding component to be added into a polyamide resin system, the toughness of the material can be improved, the water contact angle of the prepared composite material can reach 80.1 degrees, and the water resistance and hydrolysis resistance are excellent.

Description

Technical Field

[0001] This application belongs to the field of polyamide composite material technology, and in particular relates to a corrosion-resistant, hydrolysis-resistant, and toughened polyamide composite material and its preparation method. Background Technology

[0002] Polyamide composites are high-performance engineering materials made from polyamide resin as a matrix through modification such as filling, blending, or reinforcement. Due to their excellent mechanical strength, heat resistance, wear resistance, and processing fluidity, they are used in fields such as electronics, electrical engineering, and industrial gears and bearings.

[0003] Currently, commonly used polyamide materials in industry mainly include polycaprolactam (PA6), polyhexamethylene adipamide (PA66), and poly(ω-aminoundecanoyl) (PA11). Among them, PA66 and PA6 have significant advantages due to their relatively low price, high thermal stability, and suitability for complex processing conditions. Nevertheless, due to the influence of amide bonds in the molecular chain, the prepared materials have poor water resistance, are prone to water absorption and swelling, and are subject to hydrolysis, which limits the further application of polyamides in the field of precision instrument manufacturing.

[0004] Patent application CN113292848A discloses a hydrolysis-resistant glass fiber reinforced polyamide composite material and its preparation method. The method uses glycidyl methacrylate (GMA) as a chain extender. The epoxy groups in GMA can react with the amide groups that are broken due to hydrolysis of polyamide to re-form the connection, thereby effectively improving the hydrolysis resistance of the composite material.

[0005] The aforementioned application documents connect the broken amide bonds through the bridging effect of epoxy groups, which can improve the hydrolysis resistance of polyamide composites to a certain extent. However, due to the poor water-blocking properties of polyamide composites themselves, GMA is difficult to improve the long-term hydrolysis resistance of composites. Therefore, it is necessary to find a corrosion-resistant, hydrolysis-resistant, and toughened polyamide composite material and its preparation method. Summary of the Invention

[0006] To address the aforementioned issues and further improve the toughness of polyamide composites while enhancing their hydrolysis resistance and water barrier properties, this application provides a corrosion-resistant, hydrolysis-resistant, and toughened polyamide composite material and its preparation method.

[0007] This application first provides a method for preparing a corrosion-resistant, hydrolysis-resistant, and toughened polyamide composite material, the preparation steps of which include the following: Take 10-20 parts of polycaprolactam, mix it with 5-8 parts of composite modified particles, 2-3 parts of compatibilizer, 1-3 parts of heat resistant agent, and 0.5-1.5 parts of antioxidant, then add 50-60 parts of polyhexamethylene adipamide and continue mixing. After screw extrusion, cooling and pelletizing, and drying, the product is obtained. The composite modified particles are obtained by sintering raw materials including α-alumina, copper oxide, cuprous oxide, silicon carbide, zirconium hydrogen phosphate and sodium hypophosphite, followed by modification with fluoroalkoxysilane. The screw extrusion is configured with a temperature range of 230-265℃, a screw speed of 150-200 rpm, and a pressure of 50-100 bar.

[0008] By adopting the above technical solution, composite modified particles, as an additive component, can improve the toughness of polyamide composite materials and enhance the overall hydrolysis resistance of the material. The composite modified particles, with α-alumina as the main phase and doped with components such as copper and phosphorus oxides, yield a solid solution alloy after sintering. Rigid silicon carbide particles dispersed within the alloy phase act as microcrack nucleation sites, enhancing microcrack initiation and promoting microcrack deflection. When the composite material is subjected to external impact, internal stress is transmitted through the long chains of polyamide molecules. Passing through the composite modified particles, this stress can induce microcracks in the alloy phase. The texture changes due to different degrees of external force and direction of action. Through the microcrack toughening mechanism, the overall toughness of the composite material is improved. After the sintered particulate product is modified with fluoroalkoxysilane, low surface energy strong hydrophobic fluorocarbon bonds are introduced on the surface. After being added to the resin system, it can be dispersed in the resin phase under mechanical action and play the role of hydrophobic barrier. At the same time, the copper salt component in the composite modified particles can inhibit the hydrolysis of amide bonds on polyamide resin in the hydrophobic barrier. When external water molecules penetrate into the resin, copper ions can compete for water binding sites and inhibit the hydrolysis behavior of polyamide material induced by water molecule intrusion.

[0009] Furthermore, the preparation steps of the composite modified particles include the following: S01. Take α-alumina, heat treat it, and then mix it with copper oxide, cuprous oxide, silicon carbide, zirconium hydrogen phosphate and sodium hypophosphite. Sinter it under an argon atmosphere, then cool it and let it stand overnight. After coarse grinding, sintered particles are obtained. S02. Take sintered particles, sonicate and dry them, then activate them, then add a fluoroalkoxysilane diluent, heat them, then filter, wash with water, dry and grind them to obtain the final product. In step S01, the mass ratio of α-alumina, copper oxide, cuprous oxide, silicon carbide, zirconium hydrogen phosphate, and sodium hypophosphite used is (6.18-6.72):(0.35-0.75):(0.51-1.17):(0.2-0.35):(0.72-0.95):(0.15-0.19). The average particle size of the α-alumina is 80-100µm; The average particle size of the cuprous oxide is 1-5µm; The average particle size of the silicon carbide is 0.5-0.7µm; The chemical formula of the sintered particles is Al. 4.6-x Cu 1.02-y Zr 1.33-z P 0.19-m O 7.2-n (PO4) 0.27-q (SiC) 0.08-r , among them, 0.11<x<0.94, 0.06<y<0.72, 0.31<z<0.34, 0.02< m<0.092, 0.42<n<2.93, 0.13<q<0.18, 0.013<r<0.052.

[0010] By adopting the above technical solution and using the above aluminum, copper, zirconium metal oxides and metal salts for sintering, a low-melting-point solid solution Al2O3-Cu-Zr-(SiC) alloy phase can be obtained. The resulting alloy is a composite alloy phase of multi-metal salts and oxides. The dispersed high-melting-point silicon carbide serves as a microcrack growth and deflection center, which can enhance the microcrack toughening ability of sintered particles.

[0011] Furthermore, in step S01, the heat treatment is as follows: set the furnace pressure to 2.5-3.3 MPa, then slowly raise the temperature to 975-1075℃ at a rate of 12.3-15.1℃ / min, maintain for 30-45 min, and then continue to raise the temperature to 1450-1500℃ and maintain for 2-3 h.

[0012] By adopting the above technical solution, high pressure and high heat treatment can promote the ceramicization of α-alumina, and when stress is applied, it is easier to induce microcracks on its surface and inside to promote the toughening effect of microcracks.

[0013] Furthermore, in step S01, the heating sintering is performed as follows: the temperature is increased to 300-350℃ at a heating rate of 5.8-7.3℃ / min and maintained for 1.5-2h, and then the temperature is increased to 910-1025℃ at a heating rate of 8.7-9.5℃ / min and maintained for 8.5-10h.

[0014] By adopting the above technical solution, the staged heating in the low-temperature zone helps to form low-melting-point compound phases in the raw material components, and the subsequent heating allows the various metal oxides and salts to continue to act and form solid solution phases.

[0015] Furthermore, in step S02, the activation treatment is as follows: take sintered particles and place them in a 0.01-0.05M acetic acid aqueous solution, set the temperature to 80-85℃, and treat for 2-3 hours; The fluorosiloxysilane is one of heptadecafluorodecyltrimethoxysilane, tridecafluorooctyltriethoxysilane, and trifluoropropyltrimethoxysilane. The fluoroalkoxysilane diluent uses ethanol as a solvent, and the mass percentage concentration of the fluoroalkoxysilane is 8%-10%.

[0016] By adopting the above technical solution, under weak acid and hydrothermal environment, the amorphous alumina on the surface of the main phase alumina of the sintered particles is converted into hydrated AlOOH, generating reactive aluminum hydroxyl groups on the particle surface. The fluoroalkoxysilane in the subsequently added diluent is hydrolyzed and grafted onto the surface of the sintered particles, thereby constructing a low surface energy hydrophobic structure on the surface of the sintered particles.

[0017] Furthermore, in step S02, the heating process involves raising the temperature to 65-80℃ and continuing for 1-2 hours.

[0018] This application also provides a corrosion-resistant, hydrolysis-resistant, and toughened polyamide composite material, which is prepared using the above-described preparation method.

[0019] Compared with the prior art, this application has the following beneficial effects: 1. This application introduces Al2O3-Cu-Zr-(SiC) sintered particles into a polyamide resin system to promote the strengthening and toughening of polyamide composites. The sintered particles are a solid solution alloy formed by sintering a ceramicized α-alumina as the main phase and doping with copper, zirconium metal oxides and metal salts. After being mixed into the polyamide resin, the internal stress of the resin can be dispersed through the microcrack toughening mechanism to improve the toughness of the material. The high-melting-point silicon carbide introduced during the sintering process is doped into the solid solution alloy and serves as a center for microcrack growth and deflection, which can further enhance the microcrack toughening effect, making the polyamide composite material have stronger toughness.

[0020] 2. This application obtains composite modified particles by treating sintered particles with fluoroalkoxysilane to improve the hydrophobic properties of the sintered particles. After treatment with fluoroalkoxysilane, the surface of the sintered particles is grafted with low surface energy and high hydrophobic fluorocarbon bonds. After dispersion, these bonds can form a hydrophobic barrier in the resin system to prevent external water molecules from penetrating the resin. At the same time, Cu salt ions in the composite modified particles play a role in enhancing the hydrolysis resistance in the hydrophobic barrier. When external water molecules penetrate into the material, Cu salt ions can compete for water molecule binding sites and inhibit the hydrolysis of amide bonds on the polyamide material induced by water molecule intrusion.

[0021] 3. Using the composite modified particles of this application as an additive component in the polyamide resin system can improve the toughness of the composite material. The water contact angle of the composite material can reach 80.1°, and it has excellent water blocking and hydrolysis resistance. Attached Figure Description

[0022] Figure 1 The results are X-ray diffraction test results of sintered particles in Example 2 of this application.

[0023] Figure 2 The results are the water contact angle test results of Examples 1-4 and Comparative Examples 1-2 of this application. Detailed Implementation

[0024] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0026] When using “including,” “having,” and “contains” as described herein, the intention is to cover non-exclusive inclusion, unless an explicit qualifying term such as “only,” “consisting of,” etc., is used, in which case another component may be added.

[0027] The terms "preferred," "more preferably," "better," and "even better" used in this application refer to embodiments of this application that provide certain beneficial effects under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude other embodiments from the scope of this application. That is, in this application, "preferred," "more preferably," "better," and "even better" are merely descriptions of implementations or embodiments with better effects, but do not constitute a limitation on the scope of protection of this application.

[0028] In this application, terms such as "further," "even more," and "particularly" are used for descriptive purposes and indicate differences in content, but should not be construed as limiting the scope of protection of this application.

[0029] In this application, "at least one" means one or more, such as one, two, or more. "Multiple" or "several" means at least two, such as two, three, etc., and "multi-layered" means at least two layers, such as two layers, three layers, etc., unless otherwise explicitly specified. In the description of this application, "several" means at least one, such as one, two, etc., unless otherwise explicitly specified.

[0030] When a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0031] Unless otherwise specified, all steps in this application may be performed sequentially or randomly. For example, the method comprising steps (a) and (b) indicates that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order; for example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc. Unless otherwise stated, singular terms may include plural forms and should not be construed as having a quantity of one.

[0032] In this application, "above" or "below" includes the number itself. For example, "below 1" includes 1.

[0033] In this application, room temperature refers to 0~40℃, including but not limited to 10~40℃, or further to 20~30℃.

[0034] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in this application, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. All reagents or instruments whose manufacturers are not specified are conventional products that can be purchased commercially. In addition to the specific methods, equipment, and materials used in the embodiments, based on the knowledge of the prior art possessed by one of ordinary skill in the art and the description in this application, any prior art methods, equipment, and materials similar to or equivalent to those described, used, or made by the methods, equipment, and materials in the embodiments of this application may be used to implement this application.

[0035] The technical solution of the present invention will be explained in detail below with reference to several representative embodiments.

[0036] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the materials and reagents used in the following examples are commercially available.

[0037] Description of raw materials used in the embodiments and comparative examples of this invention: α-Aluminum oxide (α-Al₂O₃), purity: 99.5%, 80-100µm; Copper oxide (CuO), purity: 99.9%, 1-2µm; Cuprous oxide (Cu2O), purity: 99.9%, 1-5µm; Silicon carbide (SiC), purity: 99%, 0.5-0.7µm; Zirconium hydrogen phosphate, purity: 99.5%, 2-3µm; Sodium hypophosphite, industrial grade, 20-30µm; Polyhexamethylene adipamide (PA66), density: 1.14-1.15 g / cm³ 3 ; Polycaprolactam (PA6), density: 1.12-1.13 g / cm³ 3 ; Compatibilizer, ABS-g-MAH, grafting rate ≥5.5%; Silica lime, CaO wt% ≥ 37.2%.

[0038] Preparation Example 1 Take 61.8g of α-Al2O3, place it in a muffle furnace, purge with argon and set the furnace pressure to 2.5MPa, slowly heat to 975℃ at a rate of 12.3℃ / min, maintain for 30min, then continue heating to 1450℃, maintain for 2h and then stop heating. After the product cools with the furnace, release the pressure, then add 3.5g of copper oxide, 5.1g of cuprous oxide, 2g of silicon carbide, 7.2g of zirconium hydrogen phosphate and 1.5g of sodium hypophosphite to the furnace, maintain the argon atmosphere, raise the system temperature back to 300℃ at 5.8℃ / min, maintain for 1.5h, then continue heating to 910℃ at a rate of 8.7℃ / min, maintain for 8.5h, then lower the system temperature to room temperature at a cooling gradient of 5℃ / min and let it stand overnight. Finally, grind for 1min to obtain sintered particles.

[0039] Preparation Example 2 Take 63.5g of α-Al2O3, place it in a muffle furnace, purge with argon and set the furnace pressure to 2.8MPa, slowly heat to 1000℃ at a rate of 13.2℃ / min, maintain for 35min, then continue heating to 1500℃, maintain for 2h and then stop heating. After the product cools with the furnace, release the pressure, then add 4.2g of copper oxide, 7.5g of cuprous oxide, 3.5g of silicon carbide, 7.9g of zirconium hydrogen phosphate and 1.6g of sodium hypophosphite to the furnace, maintain the argon atmosphere, raise the system temperature back to 325℃ at 6.2℃ / min, maintain for 1.5h, then continue heating to 945℃ at a rate of 8.9℃ / min, maintain for 9h, then lower the system temperature to room temperature at a cooling gradient of 5℃ / min and let it stand overnight. Finally, grind for 2min to obtain sintered particles.

[0040] Preparation Example 3 Take 67.2g of α-Al2O3, place it in a muffle furnace, purge with argon and set the furnace pressure to 3.3MPa, slowly raise the temperature to 1075℃ at a rate of 15.1℃ / min, maintain for 45min, then continue to raise the temperature to 1500℃, maintain for 3h and then stop raising the temperature. After the product cools down with the furnace, release the pressure, then add 7.5g of copper oxide, 11.7g of cuprous oxide, 3.5g of silicon carbide, 9.5g of zirconium hydrogen phosphate and 1.9g of sodium hypophosphite to the furnace, maintain the argon atmosphere, raise the system temperature back to 350℃ at 7.3℃ / min, maintain for 2h, then continue to raise the temperature to 1025℃ at a rate of 9.5℃ / min, maintain for 10h, then lower the system temperature to room temperature at a cooling gradient of 5℃ / min and let it stand overnight. Finally, grind for 2min to obtain sintered particles.

[0041] Example 1 Take 5g of sintered particles, place them in 50mL of ethanol, sonicate for 10min and dry them. Then immerse them in 50mL of 0.01M acetic acid solution, add 0.2g of citric acid, set the temperature to 80℃ and treat for 2h. Then add 5mL of ethanol dilution solution with a heptadecafluorodecyltrimethoxysilane content of 8%, increase the temperature to 65℃ and treat for 1h. Then filter to take the solid part, wash with water until neutral, dry at 60℃ under nitrogen atmosphere, and finally grind through a 100-mesh sieve to obtain composite modified particles.

[0042] Take 1 kg of PA6 and mix it with 500 g of composite modified particles, 200 g of ABS-g-MAH, 100 g of silica lime and 50 g of antioxidant 1098 for 5 min. Then add 5 kg of PA66 and continue mixing for 3 min. Transfer the mixture to a twin-screw extruder for melt blending. Set the extruder temperature parameters as follows: feed zone temperature 230℃, compression zone temperature 255℃, metering zone temperature 260℃, die zone temperature 235℃, screw speed 150 rpm, pressure 50 bar. After the extruded material is cooled, it is pelleted and then dried to obtain a corrosion-resistant, hydrolysis-resistant, and toughened polyamide composite material.

[0043] In this embodiment, the sintered particles were prepared using Preparation Example 1.

[0044] Example 2 Take 8g of sintered particles, place them in 60mL of ethanol, sonicate for 15min and dry them. Then immerse them in 50mL of 0.02M acetic acid solution, add 0.2g of citric acid, set the temperature to 85℃ and treat for 2.5h. Then add 10mL of ethanol dilution solution with a tridecafluorooctyltriethoxysilane content of 8.5%, increase the temperature to 75℃ and treat for 1h. Then filter and take the solid part, wash with water until neutral, dry at 60℃ under nitrogen atmosphere, and finally grind through a 100-mesh sieve to obtain composite modified particles.

[0045] Take 1.5 kg of PA6 and mix it with 500 g of composite modified particles, 250 g of ABS-g-MAH, 150 g of silica lime and 100 g of antioxidant 1098 for 8 min. Then add 6 kg of PA66 and continue mixing for 3 min. Transfer the mixture to a twin-screw extruder for melt blending. Set the extruder temperature parameters as follows: feed zone temperature 240℃, compression zone temperature 260℃, metering zone temperature 265℃, die zone temperature 245℃, screw speed 150 rpm, pressure 75 bar. After the extruded material is cooled, it is pelleted and then dried to obtain a corrosion-resistant, hydrolysis-resistant, and toughened polyamide composite material.

[0046] In this embodiment, the sintered particles were prepared using Preparation Example 2.

[0047] Example 3 Take 10g of sintered particles, place them in 75mL of ethanol, sonicate for 20min and then dry them. Then immerse them in 50mL of 0.05M acetic acid solution, add 0.3g of citric acid, set the temperature to 85℃ and treat for 3h. Then add 10mL of ethanol dilution solution with 10% trifluoropropyltrimethoxysilane content, raise the temperature to 80℃ and treat for 2h. Then filter to take the solid part, wash with water until neutral, dry at 60℃ under nitrogen atmosphere, and finally grind through a 100-mesh sieve to obtain composite modified particles.

[0048] Take 2 kg of PA6 and mix it with 800 g of composite modified particles, 300 g of ABS-g-MAH, 300 g of silica lime and 150 g of antioxidant 1098 for 10 min. Then add 6 kg of PA66 and continue mixing for 5 min. Transfer the mixture to a twin-screw extruder for melt blending. Set the extruder temperature parameters as follows: feed zone temperature 245℃, compression zone temperature 265℃, metering zone temperature 265℃, die zone temperature 245℃, screw speed 200 rpm, pressure 100 bar. After the extruded material is cooled, it is pelletized and then dried to obtain a corrosion-resistant, hydrolysis-resistant, and toughened polyamide composite material.

[0049] In this embodiment, the sintered particles were prepared using Preparation Example 3.

[0050] Example 4 The difference between this embodiment and Embodiment 1 is that the preparation steps of the corrosion-resistant, hydrolysis-resistant, and toughened polyamide composite material are as follows: Take 1.5 kg of PA6 and mix it with 700 g of composite modified particles, 300 g of ABS-g-MAH, 200 g of silica lime and 150 g of antioxidant 1098 for 5 min. Then add 5.5 kg of PA66 and continue mixing for 5 min. Transfer the mixture to a twin-screw extruder for melt blending. Set the extruder temperature parameters as follows: feed zone temperature 230℃, compression zone temperature 255℃, metering zone temperature 260℃, die zone temperature 235℃, screw speed 200 rpm, pressure 100 bar. After the extruded material is cooled, it is pelletized and then dried to obtain a corrosion-resistant, hydrolysis-resistant, and toughened polyamide composite material.

[0051] The remaining steps are the same as in Example 1.

[0052] Comparative Example 1 The difference between this comparative example and Example 1 is that an equal amount of α-Al2O3 was used instead of sintered particles to prepare composite modified particles.

[0053] The remaining steps are the same as in Example 1.

[0054] Comparative Example 2 The difference between this comparative example and Example 1 is that an equal amount of γ-aminopropyltriethoxysilane was used instead of heptadecafluorodecyltrimethoxysilane to prepare the diluent.

[0055] The remaining steps are the same as in Example 1.

[0056] Performance testing Test strip preparation: The polyamide composite materials of Examples 1-4 and Comparative Examples 1-2 were dried in an oven at 50°C for 3 hours and then injection molded. The barrel temperature was set as follows: Front section: 270℃; Middle section: 265℃; Rear section: 260℃; ASTM standard test specimens were prepared separately.

[0057] 1. XRD test X-ray diffraction tests were performed on the sintered particles from Example 2. The test results are as follows: Figure 1 As shown.

[0058] Analysis of Example 2 and in conjunction with Figure 1It can be seen that the prepared sintered particles are mainly composed of alumina. During the sintering process, zirconium hydrogen phosphate decomposes to produce new aluminum phosphate salts and zirconium oxide and other components. The diffraction peaks of silicon carbide on the (111), (220) and (311) crystal planes are at 2θ=35.7°, 60.0° and 71.8° respectively. During the sintering process, silicon carbide does not participate in the reaction and can be retained in the solid solution alloy phase to play the role of the central core.

[0059] 2. Apparent performance test Table 1. Apparent performance test items of test specimens in Examples 1-4 and Comparative Examples 1-2 The test results are shown in Table 2.

[0060] Table 2. Apparent performance test results of test specimens from Examples 1-4 and Comparative Examples 1-2 By comparing Examples 1-4 and Comparative Examples 1-2 with Tables 1 and 2, it can be concluded that the average decrease in tensile strength and flexural strength of the test specimens in the Examples before and after the salt spray test was 7.73% and 12.38%, respectively, which was significantly lower than the 24.09% and 31.46% of Comparative Example 2. This indicates that the Examples have stronger resistance to salt spray corrosion. Comparative Example 2, due to the lack of effective hydrophobic modification of the sintered particles, experienced severe corrosion of the test specimens in the salt spray environment, resulting in a significant decrease in strength properties. The flexural modulus and impact strength of a material can characterize its toughness. Based on the results of the flexural modulus and impact strength tests, the test specimen of Comparative Example 1 showed a high flexural modulus and low impact strength, reflecting the insufficient toughness of the material itself. Comparative Example 1 directly used α-Al2O3 as an additive component of polyamide resin. Since untreated α-Al2O3 is a rigid particle, its toughening effect on the system is relatively limited when used as an additive component. In contrast, the sintered particles used in Examples 1-4 and Comparative Example 2 were strengthened by microcrack toughening. In the polyamide resin system, stress concentration in the resin body can be avoided through the microcrack toughening mechanism, resulting in a composite material with better toughness.

[0061] 3. Water contact angle test Referring to the national standard GB / T30693-2014, water contact angle tests were conducted on test specimens from Examples 1-4 and Comparative Examples 1-2. The test results are as follows: Figure 2 As shown.

[0062] Take Examples 1-4 and Comparative Examples 1-2 and refer to Table 2 and Figure 2It can be concluded that the water contact angles of Examples 1-4 and Comparative Examples 1-2 are 74.9°, 75.3°, 80.1°, 79.6°, 71.3° and 65.9° respectively. Among them, the water contact angle of Comparative Example 2 is lower than that of the other test groups. This may be because Comparative Example 2 uses γ-aminopropyltriethoxysilane with weak hydrophobicity instead of fluorosiloxysilane. The resulting composite modified particles have poor hydrophobicity. The barrier constructed after dispersing this composite modified particle in the resin system has poor water blocking effect. Combined with the strength data before and after salt spray treatment in Table 1, it can further prove the role of fluorosiloxysilane modification in improving the water blocking and inhibiting hydrolysis of polyamide composite materials.

[0063] Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for preparing a corrosion-resistant, hydrolysis-resistant, and toughened polyamide composite material, characterized in that, The preparation steps include the following: Take 10-20 parts of polycaprolactam, mix it with 5-8 parts of composite modified particles, 2-3 parts of compatibilizer, 1-3 parts of heat resistant agent, and 0.5-1.5 parts of antioxidant, then add 50-60 parts of polyhexamethylene adipamide and continue mixing. After screw extrusion, cooling and pelletizing, and drying, the product is obtained. The composite modified particles are obtained by sintering raw materials including α-alumina, copper oxide, cuprous oxide, silicon carbide, zirconium hydrogen phosphate and sodium hypophosphite, followed by modification with fluoroalkoxysilane.

2. The method for preparing a corrosion-resistant, hydrolysis-resistant, and toughened polyamide composite material according to claim 1, characterized in that, The screw extrusion is configured with a temperature range of 230-265℃, a screw speed of 150-200 rpm, and a pressure of 50-100 bar.

3. The method for preparing a corrosion-resistant, hydrolysis-resistant, and toughened polyamide composite material according to claim 1, characterized in that, The preparation steps of the composite modified particles include the following: S01. Take α-alumina, heat treat it, and then mix it with copper oxide, cuprous oxide, silicon carbide, zirconium hydrogen phosphate and sodium hypophosphite. Sinter it under an argon atmosphere, then cool it and let it stand overnight. After coarse grinding, sintered particles are obtained. S02. Take sintered particles, sonicate and dry them, then activate them, then add a fluoroalkoxysilane diluent, heat them, then filter, wash with water, dry and grind them to obtain the final product.

4. The method for preparing a corrosion-resistant, hydrolysis-resistant, and toughened polyamide composite material according to claim 3, characterized in that, In step S01, the heat treatment is as follows: set the furnace pressure to 2.5-3.3 MPa, then slowly raise the temperature to 975-1075℃ at a rate of 12.3-15.1℃ / min, maintain for 30-45 min, and then continue to raise the temperature to 1450-1500℃ and maintain for 2-3 h.

5. The method for preparing a corrosion-resistant, hydrolysis-resistant, and toughened polyamide composite material according to claim 3, characterized in that, In step S01, the mass ratio of α-alumina, copper oxide, cuprous oxide, silicon carbide, zirconium hydrogen phosphate, and sodium hypophosphite used is (6.18-6.72):(0.35-0.75):(0.51-1.17):(0.2-0.35):(0.72-0.95):(0.15-0.19). The average particle size of the α-alumina is 80-100µm; The average particle size of the cuprous oxide is 1-5µm; The average particle size of the silicon carbide is 0.5-0.7µm.

6. The method for preparing a corrosion-resistant, hydrolysis-resistant, and toughened polyamide composite material according to claim 3, characterized in that, In step S01, the heating sintering is performed as follows: the temperature is increased to 300-350℃ at a heating rate of 5.8-7.3℃ / min and maintained for 1.5-2h, and then the temperature is increased to 910-1025℃ at a heating rate of 8.7-9.5℃ / min and maintained for 8.5-10h.

7. The method for preparing a corrosion-resistant, hydrolysis-resistant, and toughened polyamide composite material according to claim 3, characterized in that, In step S02, the fluorosiloxysilane is one of heptadecafluorodecyltrimethoxysilane, tridecafluorooctyltriethoxysilane, and trifluoropropyltrimethoxysilane. The fluoroalkoxysilane diluent uses ethanol as a solvent, and the mass percentage concentration of the fluoroalkoxysilane is 8%-10%.

8. The method for preparing a corrosion-resistant, hydrolysis-resistant, and toughened polyamide composite material according to claim 3, characterized in that, In step S02, the activation treatment is as follows: take sintered particles and place them in a 0.01-0.05M acetic acid aqueous solution, set the temperature to 80-85℃, and treat for 2-3 hours.

9. The method for preparing a corrosion-resistant, hydrolysis-resistant, and toughened polyamide composite material according to claim 3, characterized in that, In step S02, the heating process involves raising the temperature to 65-80℃ and continuing for 1-2 hours.

10. A corrosion-resistant, hydrolysis-resistant, and toughened polyamide composite material prepared by any one of the preparation methods described in claims 1-9.

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