Corrosion-resistant and high and low temperature-resistant PA66 composite material and preparation method thereof

Abstract

The invention discloses a corrosion-resistant and high and low temperature-resistant PA66 composite material and a preparation method thereof, and the corrosion-resistant and high and low temperature-resistant PA66 composite material is prepared from the following components in parts by weight: 70 to 80 parts of PA66 resin, 10 to 14 parts of EPDM-g-MAH, 3 to 5 parts of ACM, 3 to 5 parts of TPU, 12 to 18 parts of chopped glass fiber, 1 to 3 parts of white carbon black, 0.3 to 0.8 part of POE-g-GMA, 0.5 to 1 part of PETS, 0.1 to 0.5 part of silicone powder, 0.1 to 0.3 part of nano boron nitride, 0.2 to 0.4 part of copper salt antioxidant and 0.2 to 0.5 part of white mineral oil. The preparation method comprises the following steps: extruding white carbon black and white mineral oil through a first twin-screw extruder to obtain a pre-dispersed mixture, extruding EPDM-g-MAH, ACM, TPU and the pre-dispersed mixture through a second twin-screw extruder to obtain a toughening mixture, and finally extruding PA66, POE-g-GMA, a copper salt antioxidant, nano boron nitride, PETS, silicone powder and the toughening mixture through a third twin-screw extruder to obtain the PA66 composite material. Gaps of ACM are filled with TPU, low temperature resistance is improved, white carbon black forms a barrier network in gaps of chopped glass fibers, a permeation path is prolonged, permeability is reduced, corrosion resistance is improved, nano boron nitride induces PA66 resin to form a high-regularity alpha crystal form, crystallinity is improved, and high temperature resistance is improved.

Description

Technical Field

[0001] This invention relates to the field of PA66 composite material technology, and in particular to a corrosion-resistant and high / low temperature resistant PA66 composite material and its preparation method. Background Technology

[0002] PA66, or polyamide 66, commonly known as nylon 66, is widely used due to its excellent mechanical properties. However, traditional PA66 is prone to brittle fracture at low temperatures and will swell and crack upon prolonged contact with alkyd solvents, such as ethylene glycol in antifreeze. While glass fiber reinforcement of PA66 improves rigidity, its impact strength at low temperatures is weak. EPDM toughening further enhances impact strength at low temperatures, but the poor compatibility of chopped glass fibers with the matrix leads to decreased corrosion resistance, failing to address alkyd corrosion issues at both high and low temperatures. Furthermore, current PA66 composite materials are produced using single-stage extrusion molding, which can lead to material thermal sensitivity conflicts, uneven dispersion, and insufficient interfacial reactions. Especially when glass fiber reinforcement is added, the high-temperature shearing throughout the process can cause glass fiber breakage. Therefore, improvements are necessary. Summary of the Invention

[0003] To address the shortcomings of existing technologies, the present invention aims to provide a corrosion-resistant and high / low temperature resistant PA66 composite material and its preparation method, which improves impact strength, reduces high-temperature aging deformation, enhances corrosion resistance to alkyd and polyester solutions, and improves toughness while maintaining certain tensile and flexural strength.

[0004] To achieve the above objectives, the technical solution adopted by this invention is: a method for preparing a corrosion-resistant and high / low temperature resistant PA66 composite material, comprising the following steps:

[0005] Step S1, pre-dispersion extrusion step, to prepare pre-dispersion mixture.

[0006] Silica and white mineral oil are fed into the feed inlet of the first twin-screw extruder via a metering device. The extrusion temperature is set to 70–95°C, and the screw speed is set to 280–320 r / min to obtain a pre-dispersed mixture.

[0007] The die head of the first twin-screw extruder was replaced with a connecting flange, which was connected to the first buffer tank. The pre-dispersed mixture was directly extruded into the first buffer tank.

[0008] Step S2, toughening extrusion step, to prepare toughening compound.

[0009] EPDM-g-MAH, ACM, and TPU are fed into the feed inlet of the second twin-screw extruder via a metering device. The pre-dispersed mixture from the first buffer tank is also fed into the feed inlet of the second twin-screw extruder via the same metering device. The extrusion temperature is set to 150–190°C, and the screw speed is set to 300–350 r / min to obtain the toughened mixture.

[0010] The die head of the second twin-screw extruder is replaced with a connecting flange, which is connected to the second buffer box. The toughening compound is directly extruded into the second buffer box.

[0011] Step S3, composite extrusion step, to prepare composite material.

[0012] PA66, POE-g-GMA, copper salt antioxidant, nano boron nitride, PETS, and silicone powder are fed into the feed inlet of the third twin-screw extruder through a metering device. The toughening mixture in the second buffer tank is also fed into the feed inlet of the third twin-screw extruder through the metering device. The extrusion temperatures are set as follows: Zone 1 230±5℃, Zone 2 255±5℃, Zone 3 265±5℃, Zone 4 270±5℃, Zone 5 270±5℃, Zone 6 270±5℃, Zone 7 270±5℃, Zone 8 260±5℃, Zone 9 250±5℃, Zone 10 245±5℃, Zone 11 235±5℃, Zone 12 230±5℃. The screw speed is set to 450~500r / min.

[0013] Short glass fibers are added to the side feed port of zone five and extruded to obtain the composite material;

[0014] Step S4, cutting and granulation step,

[0015] After cooling the composite material, it was granulated in water and dried at 100-105℃ for 4-6 hours to obtain the PA66 composite material.

[0016] In a further technical solution, in step S1, the extrusion temperatures of each zone of the first twin-screw extruder are set as follows: zone 1 70±2℃, zone 2 85±2℃, zone 3 95±2℃, zone 4 95±2℃, zone 5 85±2℃, and zone 6 70±2℃.

[0017] In a further technical solution, in step S2, the extrusion temperatures of each zone of the second twin-screw extruder are set as follows: zone 1 150±5℃, zone 2 165±5℃, zone 3 180±5℃, zone 4 185±5℃, zone 5 180±5℃, and zone 6 170±5℃.

[0018] In a further technical solution, in step S2, the second twin-screw extruder is equipped with 45° staggered kneading blocks.

[0019] In a further technical solution, in step S3, the sixth and ninth zones of the third twin-screw extruder are evacuated to -0.08 MPa.

[0020] In a further technical solution, in step S3, the feeding pressure at the side feeding port is 0.2 to 0.4 MPa, and the side feeding speed is 15 to 25 r / min.

[0021] A corrosion-resistant and high / low temperature resistant PA66 composite material is composed of the following components in parts by weight.

[0022]

[0023]

[0024] In a further technical solution, the chopped glass fiber is a silanized chopped glass fiber with a surface treated with KH550, the surface silane coverage is ≥80%, and the length of the silanized chopped glass fiber is 0.2 to 0.6 mm.

[0025] In a further technical solution, the TPU is a polyether-type TPU with a Shore hardness of 80-90A;

[0026] POE-g-GMA is an epoxy-type POE-g-GMA with a grafting rate of 0.8% to 1.2%.

[0027] In a further technical solution, the silica is silica produced by hydrophobicating hexamethyldisilazane, with a hydrophobicity ≥90%.

[0028] The grafting rate of EPDM-g-MAH is 1.0–1.5%;

[0029] The melt index of PA66 resin is 35-45 g / 10 min.

[0030] The advantages of this invention compared to existing technologies using the above structure are as follows: A toughening system is formed by EPDM-g-MAH, ACM, and TPU. EPDM-g-MAH serves as the main toughening phase, with its maleic anhydride groups undergoing amidation with the terminal amino groups of PA66 resin, linking nonpolar EPDM molecules to the PA66 backbone and improving compatibility. Simultaneously, the long chain segments of EPDM deform under impact, absorbing impact energy. ACM acts as a low-temperature toughening agent, maintaining high elasticity even at low temperatures. Upon impact, it dissipates energy through crazing and expansion. Its polar ester groups form hydrogen bonds with the ether groups of TPU, resulting in synergistic toughening. TPU acts as a synergist, filling the gaps between the ACM dispersed phases to form an interpenetrating network, preventing a decrease in toughening efficiency caused by isolated dispersion of ACM particles at low temperatures.

[0031] The amino group of the KH550 silane coupling agent, which is treated with KH550, reacts with the hydroxyl group on the surface of the glass fiber to form Si-O-Si covalent bonds. The amino group at the other end interacts with the carboxyl group of PA66 resin, thereby enhancing the interfacial bonding force between the chopped glass fiber and PA66 resin. Combined with silica, a nanoscale barrier network is formed in the gaps between the chopped glass fibers, thereby extending the penetration path of alkyd solvent, reducing permeability, and improving corrosion resistance.

[0032] POE-g-GMA undergoes ring-opening at 255℃, reacting with the amino groups of PA66 resin to form a graft copolymer, reducing the debonding rate of chopped glass fibers. Nano-boron nitride acts as a nucleating agent, inducing PA66 resin to form a highly regular α-crystal form, increasing crystallinity and thus raising the heat distortion temperature to 215℃. Silicone powder and PETS, as compound lubricants, inhibit high-temperature processing degradation and prevent high-temperature aging and yellowing through the synergistic effect of copper ions terminating free radical chains and reducing melt viscosity.

[0033] The process involves first dispersing silica at low temperature and using white mineral oil as a carrier to prevent hydrogen bond aggregation of silica particles, resulting in a 3-fold increase in barrier efficiency compared to single high-temperature extrusion. A second, medium-temperature extrusion constructs a toughening network, precisely controlling the temperature within the viscoelastic window of TPU—25°C above the melting point but below the decomposition temperature. Combined with a 45° staggered kneading block applying controllable shear force, this promotes complete TPU coating of ACM, improving impact strength. In contrast, at 270°C in a single extrusion process, TPU melting leads to ACM breakage and decreased impact strength. A third, high-temperature extrusion, with chopped glass fibers fed to the five-zone side of the fully plasticized melt, reduces melt viscosity and fiber breakage, achieving a chopped glass fiber length retention rate of up to 92%. This three-stage stepped temperature extrusion process ensures PA66 resin compatibility with both TPU and ACM, improving TPU molecular weight retention and preventing the mutual inhibition of component functions that can occur with single extrusion.

[0034] The first twin-screw extruder is connected to the second twin-screw extruder via a first buffer box, and the second twin-screw extruder is connected to the third twin-screw extruder via a second buffer box, forming a continuous extrusion production line that eliminates the need for batch extrusion and improves production efficiency. Attached Figure Description

[0035] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0036] Figure 1 This is a flowchart of the preparation process of the present invention;

[0037] Figure 2 This is a summary table of the impact strength test results of the present invention;

[0038] Figure 3This is a schematic diagram of the structure of the standard specimen for impact strength testing according to the present invention;

[0039] Figure 4 This is a diagram illustrating the testing process of the standard specimen 1 for impact strength testing under condition 3 of the present invention;

[0040] Figure 5 This is a diagram illustrating the testing process of the standard specimen 1 for impact strength testing under condition 6 of the present invention;

[0041] Figure 6 This is a diagram showing the state of the standard specimen 1 for impact strength testing of the present invention after testing under condition 1;

[0042] Figure 7 This is a diagram showing the state of the standard specimen 1 for impact strength testing of the present invention after testing under condition 2;

[0043] Figure 8 This is a diagram showing the state of the standard specimen 1 for impact strength testing of the present invention after testing under condition 3;

[0044] Figure 9 This is a diagram showing the state of the standard specimen 1 for impact strength testing of the present invention after testing under condition 6;

[0045] Figure 10 This is a diagram illustrating the testing process of the standard specimen 2 for impact strength testing under condition 3 of the present invention;

[0046] Figure 11 This is a diagram illustrating the testing process of the standard specimen 2 for impact strength testing under condition 6 of the present invention;

[0047] Figure 12 This is a diagram showing the state of the standard specimen 2 for impact strength testing of the present invention after testing under condition 1;

[0048] Figure 13 This is a diagram showing the state of the standard specimen 2 for impact strength testing of the present invention after testing under condition 2;

[0049] Figure 14 This is a diagram showing the state of the standard specimen 2 for impact strength testing of the present invention after testing under condition 3;

[0050] Figure 15 This is a diagram showing the state of the standard specimen 2 for impact strength testing of the present invention after testing under condition 6;

[0051] Figure 16 This is a summary table of the test results for the bending strength test of this invention;

[0052] Figure 17 This is a diagram illustrating the testing process of the standard specimen 1 for the bending strength test of this invention under condition 3;

[0053] Figure 18 This is a diagram illustrating the testing process of the standard specimen 1 for the bending strength test of this invention under condition 4.

[0054] Figure 19 This is a diagram showing the state of the standard specimen 1 for the bending strength test of the present invention after testing under condition 1;

[0055] Figure 20 This is a diagram showing the state of the standard specimen 1 for the bending strength test of the present invention after testing under condition 2;

[0056] Figure 21 This is a diagram showing the state of the standard specimen 1 for the bending strength test of the present invention after testing under condition 3;

[0057] Figure 22 This is a diagram showing the state of the standard specimen 1 for the bending strength test of the present invention after testing under condition 4;

[0058] Figure 23 This is a bending curve diagram of the standard specimen 1 for the bending strength test of the present invention under condition 1;

[0059] Figure 24 This is a bending curve diagram of the standard specimen 1 for the bending strength test of the present invention under condition 2;

[0060] Figure 25 This is a bending curve diagram of the standard specimen 1 for the bending strength test of the present invention under condition 3;

[0061] Figure 26 This is a bending curve diagram of the standard specimen 1 for the bending strength test of the present invention under condition 4;

[0062] Figure 27 This is a diagram illustrating the testing process of the standard specimen 2 for the bending strength test of this invention under condition 3;

[0063] Figure 28 This is a diagram illustrating the testing process of the standard specimen 2 for the bending strength test of this invention under condition 4;

[0064] Figure 29 This is a diagram showing the state of the standard specimen 2 for the bending strength test of the present invention after testing under condition 1;

[0065] Figure 30 This is a diagram showing the state of the standard specimen 2 for the bending strength test of the present invention after testing under condition 2;

[0066] Figure 31 This is a diagram showing the state of the standard specimen 2 for the bending strength test of the present invention after testing under condition 3;

[0067] Figure 32This is a diagram showing the state of the standard specimen 2 for the bending strength test of the present invention after testing under condition 4;

[0068] Figure 33 This is a bending curve diagram of the standard specimen 2 for the bending strength test of the present invention under condition 1;

[0069] Figure 34 This is a bending curve diagram of the standard specimen 2 for the bending strength test of the present invention under condition 2;

[0070] Figure 35 This is a bending curve diagram of the standard specimen 2 for the bending strength test of the present invention under condition 3;

[0071] Figure 36 This is a bending curve diagram of the standard specimen 2 for the bending strength test of the present invention under condition 4;

[0072] Figure 37 This is a diagram showing the state of the standard sample 1 of the present invention immersed in a polyester solution under high temperature conditions;

[0073] Figure 38 This is a diagram showing the state of the standard sample 1 of the present invention after being immersed in a polyester solution at high temperature and then bent 180°.

[0074] Figure 39 This is a diagram showing the state of the standard sample 1 of the present invention immersed in an alcohol solution at a high temperature.

[0075] Figure 40 This is a diagram showing the state of the standard sample 1 of the present invention after being immersed in an alcohol solution at high temperature and then bent 180°.

[0076] Figure 41 This is a diagram showing the state of the standard sample 2 of the present invention immersed in a polyester solution under high temperature conditions;

[0077] Figure 42 This is a diagram showing the state of the standard sample 2 of the present invention after being immersed in a polyester solution at high temperature and then bent 180°.

[0078] Figure 43 This is a diagram showing the state of the standard sample 2 of the present invention immersed in an alcohol solution at a high temperature.

[0079] Figure 44 This is a diagram showing the state of the standard sample 2 of the present invention after being immersed in an alcohol solution at high temperature and then bent 180°.

[0080] In the picture:

[0081] 11 First twin-screw extruder, 12 Second twin-screw extruder, 13 Third twin-screw extruder;

[0082] 21 First buffer box, 22 Second buffer box. Detailed Implementation

[0083] The following are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention.

[0084] A method for preparing a corrosion-resistant and high / low temperature resistant PA66 composite material includes the following steps:

[0085] Step S1, pre-dispersion extrusion step, to prepare pre-dispersion mixture.

[0086] Silica and white mineral oil are fed into the feed inlet of the first twin-screw extruder 11 through a quantitative feeding device. The extrusion temperature is set as follows: Zone 1 70℃, Zone 2 85℃, Zone 3 95℃, Zone 4 95℃, Zone 5 85℃, and Zone 6 70℃. The screw speed is set to 300 r / min to obtain a pre-dispersed mixture. At low temperature, the white mineral oil wets the surface of the silica to prevent subsequent high-temperature agglomeration. The quantitative feeding device is a screw quantitative feeder or a loss-in-weight quantitative feeder.

[0087] like Figure 1 As shown, the die head of the first twin-screw extruder 11 is replaced with a connecting flange, which is connected to the first buffer box 21. The pre-dispersed mixture is directly extruded into the first buffer box 21.

[0088] Step S2, toughening extrusion step, to prepare toughening compound.

[0089] EPDM-g-MAH, ACM, and TPU are fed into the inlet of the second twin-screw extruder 12 via a metering device. The pre-dispersed mixture from the first buffer tank 21 is also fed into the inlet of the second twin-screw extruder 12 via the same metering device. The extrusion temperatures are set as follows: Zone 1 150℃, Zone 2 165℃, Zone 3 180℃, Zone 4 185℃, Zone 5 180℃, and Zone 6 170℃. The screw speed is set to 330 r / min to obtain the toughened mixture. The second twin-screw extruder 12 is equipped with 45° staggered kneading blocks.

[0090] The die head of the second twin-screw extruder 12 is replaced with a connecting flange, which is connected to the second buffer box 22. The toughening mixture is directly extruded into the second buffer box 22.

[0091] Medium-temperature extrusion avoids TPU degradation and ACM phase breakage, and improves the TPU molecular weight retention rate.

[0092] Step S3, composite extrusion step, to prepare composite material.

[0093] PA66, POE-g-GMA, copper salt antioxidant, nano boron nitride, PETS, and silicone powder are fed into the feed inlet of the third twin-screw extruder 13 through a metering device. The toughening mixture in the second buffer tank 22 is also fed into the feed inlet of the third twin-screw extruder 13 through the metering device. The extrusion temperatures are set as follows: Zone 1: 230℃, Zone 2: 255℃, Zone 3: 265℃, Zone 4: 270℃, Zone 5: 270℃, Zone 6: 270℃, Zone 7: 270℃, Zone 8: 260℃, Zone 9: 250℃, Zone 10: 245℃, Zone 11: 235℃, Zone 12: 230℃. The screw speed is set to 480 r / min.

[0094] Short glass fibers are added to the side feed port of zone 5, the feeding pressure is 0.3MPa, the side feed speed is 20r / min, and the vacuum in zones 6 and 9 is evacuated to -0.08MPa. The vacuum in zone 6 is used to remove residual small molecules of white mineral oil, and the vacuum in zone 9 is used to discharge the by-products of TPU and ACM compounding. Finally, the compound material is extruded.

[0095] High-temperature extrusion completes the melting of PA66 resin, while short-cut glass fibers are added to the fifth zone. The temperature of the fifth zone is set to 270℃ to ensure that the melt is fully plasticized. However, the actual melt temperature is lower than the set temperature. After the addition of short-cut glass fibers, the melt temperature in the sixth zone drops to 255℃, where the POE-g-GMA epoxy group undergoes a ring-opening reaction. After reaching the seventh zone, the melt temperature rises to 257℃, completing the reaction.

[0096] Step S4, cutting and granulation step,

[0097] After cooling the composite material, it was pelletized in water and dried at 100°C for 6 hours to obtain the PA66 composite material.

[0098] The process involves first dispersing silica at low temperature and using white mineral oil as a carrier to prevent hydrogen bond aggregation of silica particles, resulting in a 3-fold increase in barrier efficiency compared to single high-temperature extrusion. A second, medium-temperature extrusion constructs a toughening network, precisely controlling the temperature within the viscoelastic window of TPU—25°C above the melting point but below the decomposition temperature. Combined with a 45° staggered kneading block applying controllable shear force, this promotes complete TPU coating of ACM, improving impact strength. In contrast, at 270°C in a single extrusion process, TPU melting leads to ACM breakage and decreased impact strength. A third, high-temperature extrusion, with chopped glass fibers fed to the five-zone side of the fully plasticized melt, reduces melt viscosity and fiber breakage, achieving a chopped glass fiber length retention rate of up to 92%. This three-stage stepped temperature extrusion process ensures PA66 resin compatibility with both TPU and ACM, improving TPU molecular weight retention and preventing the mutual inhibition of component functions that can occur with single extrusion.

[0099] The first twin-screw extruder 11 and the second twin-screw extruder 12 are connected by the first buffer box 21, and the second twin-screw extruder 12 and the third twin-screw extruder 13 are connected by the second buffer box 22, forming a continuous extrusion production line. This eliminates the need for batch extrusion, thereby improving production efficiency. The quantitative feeding device precisely controls the proportions by quantitatively feeding each material. The quantitative feeding device can be a quantitative pump or a screw quantitative feeder.

[0100] A corrosion-resistant and high / low temperature resistant PA66 composite material is composed of the following components in parts by weight.

[0101]

[0102] A toughening system is formed using EPDM-g-MAH, ACM, and TPU. EPDM-g-MAH serves as the main toughening phase, with its maleic anhydride groups undergoing amidation with the terminal amino groups of PA66 resin. This links nonpolar EPDM molecules to the PA66 backbone, improving compatibility. Simultaneously, the long chain segments of EPDM deform under impact, absorbing impact energy. ACM acts as a low-temperature toughening agent, maintaining high elasticity even at low temperatures. Upon impact, it dissipates energy through crazing and expansion. Its polar ester groups form hydrogen bonds with the ether groups of TPU, resulting in synergistic toughening. TPU acts as a synergist, filling the gaps between the ACM dispersed phases to form an interpenetrating network, preventing a decrease in toughening efficiency caused by isolated dispersion of ACM particles at low temperatures.

[0103] Specifically, the chopped glass fibers are silanized chopped glass fibers with a surface treated with KH550, exhibiting a silane coverage of ≥80% and a length of 0.4 mm. The amino groups of the KH550 silane coupling agent in the silanized chopped glass fibers react with the hydroxyl groups on the glass fiber surface to form Si-O-Si covalent bonds. The amino groups at the other end interact with the carboxyl groups of the PA66 resin, enhancing the interfacial bonding between the chopped glass fibers and the PA66 resin. Combined with silica, this forms a nanoscale barrier network in the gaps between the chopped glass fibers, thereby extending the penetration path of the alkyd solvent, reducing permeability, and improving corrosion resistance. The length of the silanized chopped glass fibers is 0.2-0.6 mm to reduce runner blockage during subsequent injection molding of PA66 composite products. The diameter of the silanized chopped glass fibers is 9-13 μm to ensure a balance between rigidity and processability.

[0104] Specifically, the TPU is a polyether-type TPU with a Shore hardness of 85A; polyester-type TPU will cause hydrolysis resistance to fail, while polyether-type TPU maintains hydrolysis resistance and avoids hydrolysis after wetting.

[0105] POE-g-GMA is an epoxy-type POE-g-GMA with a grafting rate of 1.0%. POE-g-GMA undergoes ring-opening at 255℃, reacting with the amino groups of PA66 resin to form a graft copolymer, reducing the debonding rate of chopped glass fibers. Nano-boron nitride particles with a diameter ≤50nm act as nucleating agents, inducing PA66 resin to form a highly regular α-crystal form, increasing crystallinity and thus raising the heat distortion temperature to 215℃. Silicone powder and PETS are used as compound lubricants; through the synergistic effect of copper ions terminating free radical chains and reducing melt viscosity, they inhibit high-temperature processing degradation and prevent high-temperature aging and yellowing.

[0106] Specifically, the silica is a silica produced by hydrophobicating hexamethyldisilazane, with a hydrophobicity ≥90%; the grafting rate of EPDM-g-MAH is 1.3%; and the melt index of PA66 resin is 40 g / 10 min.

[0107] PETS is used for internal lubrication, reducing melt viscosity and promoting the wetting of chopped glass fibers; silicone powder is used for external lubrication and thermal stabilization, reducing melt adhesion to the wall, and copper ions inhibit thermal oxidative degradation; white mineral oil is used as a carrier, extruding and dispersing silica in step S1, and also has a plasticizing function, improving the flexibility of the TPU phase.

[0108] EPDM-g-MAH is maleic anhydride-grafted ethylene propylene diene monomer (EPDM) rubber, ACM is acrylate rubber, polyether-type TPU is polyether-type thermoplastic polyurethane, PETS is pentaerythritol stearate, and silicone powder is polydimethylsiloxane (PDMS). Silicone powder is a powder made from liquid polydimethylsiloxane through crosslinking or adsorption. The full chemical name of epoxy-type POE-g-GMA is ethylene-octene copolymer grafted glycidyl methacrylate. The main chain is ethylene-octene copolymer (POE), which is a polyolefin elastomer. The side chain is grafted with glycidyl methacrylate (GMA) groups, and the GMA groups contain active epoxy groups (COC three-membered ring structure).

[0109] Traditional uncomposite PA66 was injection molded into standard test specimens 1 according to standard dimensions. The PA66 composite material obtained by this invention was injection molded into standard test specimens 2 according to standard dimensions. The following tests were conducted in dry conditions, different temperature and humidity combinations (dry state at room temperature, dry state at low temperature, humidified state at room temperature, humidified state at low temperature), and high temperature environments:

[0110] Impact strength test such as Figures 2 to 15 As shown: Figure 3 As shown, the notched impact type A (cantilever beam) test was conducted according to the ISO 180 / 1A standard. The standard specimens were subjected to impact strength tests under the following environmental conditions:

[0111] Condition 1: Dry state

[0112] Keep the standard sample dry and conduct the test at room temperature in an environment free from moisture. The room temperature is set to 23°C.

[0113] Condition 2: Dry state, room temperature 23 degrees Celsius, 50% RH, placed for 16 hours.

[0114] Keep the standard sample dry and place it in an environment with room temperature and humidity controlled at 50%RH for 16 hours before testing. The room temperature is set at 23℃ to simulate normal temperature and humidity conditions, which is close to the normal daily use environment.

[0115] Condition 3: Dry, low temperature -40 degrees Celsius for 16 hours, then warmed back to room temperature for 20 seconds.

[0116] Keep the standard sample dry and place it in an environment of -40℃ and no moisture for 16 hours. Then, place the standard sample at room temperature for 20 seconds before testing. The room temperature is set to 23℃ to simulate the use environment at extreme low temperature.

[0117] Condition 4: Humidify at room temperature (23°C) and 50% RH for 16 hours.

[0118] The standard sample was soaked in water and placed in an environment with room temperature and humidity controlled at 50%RH for 16 hours before testing. The room temperature was set at 23℃. The soaking water will have a plasticizing effect on the standard sample, simulating the normal use environment during soaking.

[0119] Condition 5: Humidification at -40 degrees Celsius for 16 hours, followed by warming for 20 seconds.

[0120] The standard sample was wetted and placed in an environment of -40℃ and no water vapor for 16 hours. Then, the standard sample was placed at room temperature for 20 seconds before testing. The room temperature was set to 23℃ to simulate the use environment under extreme low temperature and immersion.

[0121] Condition 6: High temperature 150 degrees Celsius for 16 hours, then reheat for 1 hour.

[0122] Keep the standard sample dry and place it in an environment of 150°C without moisture for 16 hours. Then, place the standard sample at room temperature for 1 hour before testing. The room temperature is set to 23°C to simulate the use environment after rapid aging under extreme high temperature and after warming.

[0123] The average value was obtained through five repeated tests. The impact process data is as follows: Figure 2 As shown.

[0124] Under condition 1, the impact strength of standard specimen 1 is 1.793 KJ / m², while the average value of standard specimen 2 under various impact strengths is 26.771 KJ / m². Under condition 2, the impact strength of standard specimen 1 is 1.940 KJ / m², while the average value of standard specimen 2 under various impact strengths is 26.487 KJ / m². Under condition 3, the impact strength of standard specimen 1 is 2.132 KJ / m², while the average value of standard specimen 2 under various impact strengths is 11.777 KJ / m². Under condition 4, the impact strength of standard specimen 1 is 5.705 KJ / m², while the average value of standard specimen 2 under various impact strengths is... The impact strength of standard specimen 1 is 30.878 KJ / m2; under condition 5, the impact strength of standard specimen 1 is 2.402 KJ / m2, while the average value of standard specimen 2 under various impact strengths is 13.912 KJ / m2; under condition 6, the impact strength of standard specimen 1 is 0.710 KJ / m2, while the average value of standard specimen 2 under various impact strengths is 26.458 KJ / m2; the impact strength of standard specimen 1 is severely reduced under extreme high temperature, and its impact strength under all test conditions is lower than that of standard specimen 2. In particular, the impact strength of standard specimen 2 after aging at extreme high temperature is still comparable to that under normal use conditions.

[0125] Bending strength testing shall be conducted in accordance with ISO 178 standard. Figures 16 to 36 As shown:

[0126] The standard specimens were subjected to bending strength tests under the following environments and conditions.

[0127] Condition 1: Dry state

[0128] Keep the standard sample dry and conduct the test at room temperature in an environment free from moisture. The room temperature is set to 23°C.

[0129] Condition 2: Place at room temperature (23°C) and 50% RH for 88 hours.

[0130] Keep the standard sample dry and place it in an environment with room temperature and humidity controlled at 50%RH for 88 hours before testing. The room temperature is set at 23℃ to simulate a normal daily use environment.

[0131] Condition 3: Low temperature -40 degrees Celsius for 88 hours, then warmed back to room temperature for 20 seconds.

[0132] Keep the standard sample dry and place it in an environment of -40℃ and no moisture for 88 hours. Then, place the standard sample at room temperature for 20 seconds before testing. The room temperature is set to 23℃ to simulate the use environment at extreme low temperature.

[0133] Condition 4: High temperature 150 degrees Celsius for 16 hours, then return to room temperature for 1 hour.

[0134] Keep the standard sample dry and place it in an environment of 150℃ without moisture for 16 hours. Then, place the standard sample at room temperature for 1 hour before testing. The room temperature is set to 23℃ to simulate the extreme high temperature environment and to induce rapid aging.

[0135] The average value was obtained through five repeated tests. Detailed results of the bending strength test are as follows: Figure 16 As shown.

[0136] Under condition 1, the flexural strength of standard specimen 1 is 111.471 MPa, while the average value of standard specimen 2 under various impact strengths is 58.522 MPa; under condition 2, the flexural strength of standard specimen 1 is 99.757 MPa, while the average value of standard specimen 2 under various impact strengths is 51.277 MPa; under condition 1, the flexural strength of standard specimen 3 is 131.868 MPa, while the average value of standard specimen 2 under various impact strengths is 70.803 MPa; under condition 4, the flexural strength of standard specimen 1 is 111.874 MPa, while the flexural strength of standard specimen 2 is 62.451 MPa; during the test, if... Figure 19 As shown, standard spline 1 fractured under condition 1, as follows: Figure 22 As shown, breakage occurred under condition 4, as follows: Figures 29 to 32 As shown, standard specimen 2 did not break or fracture under any conditions. Therefore, standard specimen 1 has poor toughness and high brittleness, and is prone to breakage after bending. In contrast, standard specimen 2 has high toughness and low brittleness, and is not prone to breakage after bending. Furthermore, it can still maintain a bending strength of more than 50 MPa under various conditions.

[0137] Alkyd and polyester resistance tests, such as Figures 37 to 44 As shown:

[0138] Standard samples were immersed in polyester and alcohol solutions at 150℃ for one hour, respectively, and then subjected to a 180° bending test. Standard sample 1 fractured after bending in both polyester and alcohol solutions, while standard sample 2 did not fracture after bending in either solution. By accelerating the penetration of polyester and alcohol solutions in an extreme high-temperature environment to simulate prolonged immersion, standard sample 1 fractured after bending in both solutions, exhibiting poor corrosion resistance, while standard sample 2 showed no fracture, demonstrating strong corrosion resistance.

[0139] Through various tests, the standard sample 2 prepared using the components and methods of this invention showed significantly improved impact resistance under various environmental conditions. It can not only adapt to extreme high and low temperatures, but also resist polyester and alkyd liquids, exhibiting high corrosion resistance. While maintaining a certain bending strength and tensile strength, it improves toughness and is less prone to breakage.

[0140] The above description is only a preferred embodiment of the present invention. For those skilled in the art, there will be changes in the specific implementation and application scope based on the ideas of the present invention. The content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for preparing a corrosion-resistant and high / low temperature resistant PA66 composite material, characterized in that: Includes the following steps, Step S1, pre-dispersion extrusion step, to prepare pre-dispersion mixture. Silica and white mineral oil were fed into the feed inlet of the first twin-screw extruder (11) via a metering device. The extrusion temperature was set to 70–95°C, and the screw speed was set to 280–320 r / min to obtain a pre-dispersed mixture. The die head of the first twin-screw extruder (11) is replaced with a connecting flange, which is connected to the first buffer box (21) through the connecting flange. The pre-dispersed mixture is directly extruded into the first buffer box (21). Step S2, toughening extrusion step, to prepare toughening compound. EPDM-g-MAH, ACM, and TPU were fed into the feed inlet of the second twin-screw extruder (12) via a quantitative feeding device. The pre-dispersed mixture in the first buffer tank (21) was also fed into the feed inlet of the second twin-screw extruder (12) via the quantitative feeding device. The extrusion temperature was set to 150–190°C, and the screw speed was set to 300–350 r / min to obtain the toughened mixture. The die head of the second twin-screw extruder (12) is replaced with a connecting flange, which is connected to the second buffer box (22) through the connecting flange. The toughening mixture is directly extruded into the second buffer box (22). Step S3, composite extrusion step, to prepare composite material. PA66, POE-g-GMA, copper salt antioxidant, nano boron nitride, PETS and silicone powder are fed into the feed inlet of the third twin-screw extruder (13) through a quantitative feeding device. The toughening mixture in the second buffer box (22) is fed into the feed inlet of the third twin-screw extruder (13) through a quantitative feeding device. The extrusion temperature is set to 230±5℃ in zone 1, 255±5℃ in zone 2, 265±5℃ in zone 3, 270±5℃ in zone 4, 270±5℃ in zone 5, 270±5℃ in zone 6, 270±5℃ in zone 7, 270±5℃ in zone 8, 260±5℃ in zone 9, 250±5℃ in zone 10, 245±5℃ in zone 11, 235±5℃ in zone 12, and 230±5℃ in zone 12. The screw speed is set to 450~500r / min. Short glass fibers are added to the side feed port of zone five and extruded to obtain the composite material; Step S4, cutting and granulation step, After cooling the composite material, it was granulated in water and dried at 100-105°C for 4-6 hours to obtain the PA66 composite material.

2. The method for preparing a corrosion-resistant and high / low temperature resistant PA66 composite material according to claim 1, characterized in that: In step S1, the extrusion temperatures of each zone of the first twin-screw extruder (11) are set as follows: zone 1 70±2℃, zone 2 85±2℃, zone 3 95±2℃, zone 4 95±2℃, zone 5 85±2℃, and zone 6 70±2℃.

3. The method for preparing a corrosion-resistant and high / low temperature resistant PA66 composite material according to claim 1, characterized in that: In step S2, the extrusion temperatures of each zone of the second twin-screw extruder (12) are set as follows: Zone 1 150±5℃, Zone 2 165±5℃, Zone 3 180±5℃, Zone 4 185±5℃, Zone 5 180±5℃, and Zone 6 170±5℃.

4. The method for preparing a corrosion-resistant and high / low temperature resistant PA66 composite material according to claim 1, characterized in that: In step S2, the second twin-screw extruder (12) is configured with 45° staggered kneading blocks.

5. The method for preparing a corrosion-resistant and high / low temperature resistant PA66 composite material according to claim 1, characterized in that: In step S3, the sixth and ninth zones of the third twin-screw extruder (13) are evacuated to -0.08 MPa.

6. The method for preparing a corrosion-resistant and high / low temperature resistant PA66 composite material according to claim 1, characterized in that: In step S3, the feeding pressure at the side feeding port is 0.2 to 0.4 MPa, and the side feeding speed is 15 to 25 r / min.

7. A corrosion-resistant and high / low temperature resistant PA66 composite material, prepared according to any one of claims 1 to 6, characterized in that: It consists of the following components in parts by weight.

8. The corrosion-resistant and high / low temperature resistant PA66 composite material according to claim 7, characterized in that: The chopped glass fiber is a silanized chopped glass fiber with a surface treated with KH550, a surface silane coverage of ≥80%, and a length of 0.2-0.6 mm.

9. The corrosion-resistant and high / low temperature resistant PA66 composite material according to claim 7, characterized in that: The TPU is a polyether-type TPU with a Shore hardness of 80-90A. The POE-g-GMA is an epoxy-type POE-g-GMA with a grafting rate of 0.8% to 1.2%.

10. The corrosion-resistant and high / low temperature resistant PA66 composite material according to claim 7, characterized in that: The silica is silica produced by hydrophobicating hexamethyldisilazane, with a hydrophobicity ≥90%. The grafting rate of the EPDM-g-MAH is 1.0–1.5%; The melt index of the PA66 resin is 35-45 g / 10 min.

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