Wear-resistant and scratch-resistant nylon composite material and preparation method thereof

Abstract

The application provides a wear-resistant and scratch-resistant nylon composite material and a preparation method thereof, and belongs to the technical field of high polymer composite materials. The composite material comprises a polyamide resin main body, an interface buffer anchoring master batch, modified talcum powder, short glass fibers and an auxiliary component. Modified silicon dioxide powder in the interface buffer anchoring master batch is prepared by hydrolysis and condensation of nano silicon dioxide, methyl triethoxysilane, dimethyl diethoxysilane and KH560, and is used in the composite after being made into the interface buffer anchoring master batch with PA66 and a compatilizer. The preparation method is helpful to improve the dispersion and interface bonding state of the inorganic phase in the polyamide system, reduce local stress concentration, interface debonding and surface whitening problems in the scratching process, so that the material has good scratch resistance and surface layer stability while maintaining certain mechanical support and wear resistance.

Description

Technical Field

[0001] This invention belongs to the field of polymer composite materials technology, and relates to a wear-resistant and scratch-resistant nylon composite material and its preparation method. Background Technology

[0002] Polyamide composites, due to their good strength, toughness, heat resistance, and processability, have been widely used in automotive interior and exterior parts, electronic and electrical structural components, transmission components, and various industrial parts. For these applications, in addition to having certain load-bearing capacity and wear resistance, the materials also need to maintain good surface appearance stability during long-term friction, contact, and assembly, especially reducing residual scratches, surface whitening, and roughening caused by contact with sharp objects.

[0003] Existing polyamide wear-resistant systems are typically modified by adding glass fibers, inorganic fillers, and lubricating components. These methods can improve material rigidity, dimensional stability, or reduce wear, but they primarily focus on overall wear resistance, coefficient of friction, or load-bearing capacity, with relatively insufficient consideration given to the stress characteristics of the surface layer under scratching conditions. Scraping behavior is not entirely the same as conventional continuous wear; it more easily generates instantaneous concentrated loads on the material surface, inducing micro-area plowing, localized plastic flow, interfacial debonding, and microcrack propagation, further manifesting as noticeable scratch residue, enhanced whitening, and decreased surface texture.

[0004] For polyamide systems filled with glass fiber or hard minerals, due to the significant modulus difference between the reinforcing phase and the matrix, if the interfacial bonding is insufficient or the filler is unevenly dispersed, localized hard spots and stress concentration areas can easily form on the surface under scratch loads. In this case, microvoids, pull-out, or peeling are more likely to occur around the reinforcing phase, and the increased discontinuous structure on the material surface leads to enhanced light scattering, resulting in whitening. On the other hand, while relying solely on lubricating components to reduce frictional resistance can improve initial sliding behavior to some extent, in multiphase systems, problems such as insufficient interfacial fixation, surface migration, or limited long-term stability may still exist, making it difficult to simultaneously achieve wear resistance, scratch resistance, and appearance retention.

[0005] Therefore, it is still necessary to provide a composite material and its preparation method that can further improve the residual marks, whitening degree and interface stability after surface scratching while maintaining the mechanical properties and wear resistance of polyamide composite materials. Summary of the Invention

[0006] To address the aforementioned problems, the present invention aims to provide a wear-resistant and scratch-resistant nylon composite material and its preparation method. The composite material comprises a polyamide resin matrix, an interface buffer anchoring masterbatch, modified talc powder, chopped glass fibers, and auxiliary components. The modified silica powder in the interface buffer anchoring masterbatch is obtained by hydrolysis and condensation of nano-silica with methyltriethoxysilane, dimethyldiethoxysilane, and KH560, and is first combined with PA66 and a compatibilizer to form an interface buffer anchoring masterbatch before being used in the composite. This preparation method helps improve the dispersion and interfacial bonding of the inorganic phase in the polyamide system, reducing local stress concentration, interfacial debonding, and surface whitening problems during scratching. This allows the material to maintain certain mechanical support and wear resistance while possessing good scratch resistance and surface stability.

[0007] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for preparing a wear-resistant and scratch-resistant nylon composite material, the method comprising: S1: Nano-silica was dispersed in a mixed solvent to obtain a dispersion. The pH of the dispersion was adjusted with a first acetic acid solution. Methyltriethoxysilane and dimethyldiethoxysilane were added to obtain reaction solution A. Hydrolysis and condensation were performed, and the pH was adjusted with an ammonia solution. The reaction continued to obtain reaction solution B. KH560 ethanol solution was added, and the pH was adjusted with a second acetic acid solution. The reaction continued. After the reaction was completed, the product was separated by centrifugation, washed first with ethanol, and then washed with n-hexane. The product was vacuum dried and pulverized to obtain modified silica powder. S2: Prepare a silane coupling agent aqueous alcohol solution, adjust the pH with a first acetic acid solution, pre-hydrolyze at room temperature to obtain a modified solution, add talc powder to the modified solution, stir and treat, separate the solid and liquid and dry to obtain modified talc powder; S3: PA66 is vacuum dried to obtain a carrier resin. The carrier resin, modified silica powder and compatibilizer are mixed to obtain a mixture. The mixture is added to a twin-screw extruder and melt-extruded, water-cooled pelletized and dried to obtain an interface buffer anchoring masterbatch. S4: The polyamide resin matrix, interface buffer anchoring masterbatch, modified talc powder, composite antioxidant, lubricant and polytetrafluoroethylene micro powder are mixed, dried and added through the main feed port of a twin-screw extruder; at the same time, chopped glass fiber is added through the side feed port; after extrusion and pelletizing, composite material particles are obtained; the composite material particles are dried with circulating hot air and then molded on an injection molding machine to finally obtain wear-resistant and scratch-resistant nylon composite material.

[0008] As a preferred technical solution of the present invention, in step S1, the particle size of the nano-silica is 30-80nm, for example, it can be 30nm, 35nm, 40nm, 45nm, 50nm, 55nm, 60nm, 65nm, 70nm, 75nm or 80nm, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0009] In some optional embodiments, the volume ratio of ethanol to deionized water in the mixed solvent is (70-95):(30-5), for example, it can be (70, 72.5, 75, 77.5, 80, 82.5, 85, 87.5, 90, 92.5 or 95):(30, 27.5, 25, 22.5, 20, 17.5, 15, 12.5, 10, 7.5 or 5), but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0010] In some optional embodiments, the mass-volume ratio of the nano-silica to the mixed solvent is 1g:(10-30)mL, for example, it can be 1g:10mL, 1g:12mL, 1g:14mL, 1g:16mL, 1g:18mL, 1g:20mL, 1g:22mL, 1g:24mL, 1g:26mL, 1g:28mL or 1g:30mL, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0011] In some optional embodiments, the mass fraction of the first acetic acid solution is 5-10%, for example, it can be 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5% or 10%, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0012] In some alternative embodiments, the pH of the dispersion is adjusted to 4-5 using an acetic acid solution, for example, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9 or 5.0, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0013] In some optional embodiments, the molar ratio of methyltriethoxysilane to dimethyldiethoxysilane is (30-60):(10-35), for example, it can be (30, 33, 36, 39, 42, 45, 48, 51, 54, 57 or 60):(10, 12.5, 15, 17.5, 20, 22.5, 25, 27.5, 30, 32.5 or 35), but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0014] In some optional embodiments, the molar ratio of deionized water to the total number of hydrolyzable alkoxy groups in methyltriethoxysilane and dimethyldiethoxysilane in the mixed solution is (1.5-5.0):1, for example, it can be 1.5:1, 1.85:1, 2.2:1, 2.55:1, 2.9:1, 3.25:1, 3.6:1, 3.95:1, 4.3:1, 4.65:1 or 5.0:1, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0015] In some alternative embodiments, the hydrolysis condensation temperature is 40-60°C, for example, 40°C, 42°C, 44°C, 46°C, 48°C, 50°C, 52°C, 54°C, 56°C, 58°C or 60°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0016] In some optional embodiments, the hydrolysis-condensation time is 0.5-1.5h, for example, it can be 0.5h, 0.6h, 0.7h, 0.8h, 0.9h, 1.0h, 1.1h, 1.2h, 1.3h, 1.4h or 1.5h, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0017] In some optional embodiments, the mass fraction of the ammonia solution is 1-5%, for example, it can be 1%, 1.4%, 1.8%, 2.2%, 2.6%, 3%, 3.4%, 3.8%, 4.2%, 4.6% or 5%, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0018] In some alternative embodiments, the pH is adjusted to 6.5-7.5 using the ammonia solution, for example, 6.5, 6.6, 6.7, 6.8, 6.9, 7.0, 7.1, 7.2, 7.3, 7.4 or 7.5, but not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0019] In some optional embodiments, the temperature at which the reaction continues after adjusting the pH with the ammonia is 50-70°C, for example, 50°C, 52°C, 54°C, 56°C, 58°C, 60°C, 62°C, 64°C, 66°C, 68°C, or 70°C, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0020] In some optional embodiments, the reaction time after adjusting the pH with the ammonia is 2-3 hours, for example, 2 hours, 2.1 hours, 2.2 hours, 2.3 hours, 2.4 hours, 2.5 hours, 2.6 hours, 2.7 hours, 2.8 hours, 2.9 hours or 3 hours, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0021] In some optional embodiments, the molar ratio of KH560 to the total amount of methyltriethoxysilane and dimethyldiethoxysilane is (10-30):(40-95), for example, it can be (10, 12, 14, 16, 18, 20, 22, 24, 26, 28 or 30):(40, 45.5, 51, 56.5, 62, 67.5, 73, 78.5, 84, 89.5 or 95), but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0022] In some alternative embodiments, the mass fraction of the second acetic acid solution is 1-5%, for example, it can be 1%, 1.4%, 1.8%, 2.2%, 2.6%, 3%, 3.4%, 3.8%, 4.2%, 4.6% or 5%, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0023] In some optional embodiments, the pH of the reaction solution B is adjusted to 5.5-6.3 after adding KH560 ethanol solution. For example, it can be 5.5, 5.58, 5.66, 5.74, 5.82, 5.9, 5.98, 6.06, 6.14, 6.22 or 6.3, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0024] In some optional embodiments, the reaction solution B is further reacted at a temperature of 40-55°C after adding KH560 ethanol solution and adjusting the pH. For example, the temperature can be 40°C, 41.5°C, 43°C, 44.5°C, 46°C, 47.5°C, 49°C, 50.5°C, 52°C, 53.5°C, or 55°C, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0025] In some optional embodiments, after adding KH560 ethanol solution to the reaction solution B and adjusting the pH, the reaction time is continued for 1-2 hours, for example, 1 hour, 1.1 hours, 1.2 hours, 1.3 hours, 1.4 hours, 1.5 hours, 1.6 hours, 1.7 hours, 1.8 hours, 1.9 hours, or 2 hours, but not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0026] In some optional embodiments, the number of ethanol washes is 2-3 times, for example, 2 or 3 times, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0027] In some optional embodiments, the number of times the n-hexane is washed is 3-5 times, for example, 3 times, 4 times or 5 times, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0028] In some optional embodiments, the vacuum drying temperature is 80-110°C, for example, it can be 80°C, 83°C, 86°C, 89°C, 92°C, 95°C, 98°C, 101°C, 104°C, 107°C or 110°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0029] In some optional embodiments, the vacuum drying time is 6-10 hours, for example, 6 hours, 6.4 hours, 6.8 hours, 7.2 hours, 7.6 hours, 8 hours, 8.4 hours, 8.8 hours, 9.2 hours, 9.6 hours or 10 hours, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0030] As a preferred technical solution of the present invention, in step S2, the mass fraction of the silane coupling agent aqueous alcohol solution is 0.5-1.5%, for example, it can be 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4% or 1.5%, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0031] The silane coupling agent is KH550 or KH560.

[0032] In some optional embodiments, the volume ratio of ethanol to deionized water in the silane coupling agent aqueous alcohol solution is (60-80):(40-20), for example, it can be (60, 62, 64, 66, 68, 70, 72, 74, 76, 78 or 80):(40, 38, 36, 34, 32, 30, 28, 26, 24, 22 or 20), but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0033] In some alternative embodiments, the pH is adjusted to 4-5 using a first acetic acid solution, for example, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9 or 5.0, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0034] In some optional embodiments, the pre-hydrolysis time is 20-40 min, for example, it can be 20 min, 22 min, 24 min, 26 min, 28 min, 30 min, 32 min, 34 min, 36 min, 38 min or 40 min, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0035] In some optional embodiments, the talc powder has an equivalent flake diameter D50 of 1-3 μm and an aspect ratio of 5-30.

[0036] In some optional embodiments, the mass-to-volume ratio of talc to modified liquid is 1g:(5-15)mL, for example, it can be 1g:5mL, 1g:6mL, 1g:7mL, 1g:8mL, 1g:9mL, 1g:10mL, 1g:11mL, 1g:12mL, 1g:13mL, 1g:14mL or 1g:15mL, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0037] In some optional embodiments, the temperature of the stirring process is 40-60°C, for example, 40°C, 42°C, 44°C, 46°C, 48°C, 50°C, 52°C, 54°C, 56°C, 58°C or 60°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0038] In some optional embodiments, the stirring time is 1-2 hours, for example, it can be 1 hour, 1.1 hours, 1.2 hours, 1.3 hours, 1.4 hours, 1.5 hours, 1.6 hours, 1.7 hours, 1.8 hours, 1.9 hours or 2 hours, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0039] In some optional embodiments, the drying temperature is 110-130°C, for example, 110°C, 112°C, 114°C, 116°C, 118°C, 120°C, 122°C, 124°C, 126°C, 128°C or 130°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0040] In some optional embodiments, the drying time is 2-4 hours, for example, 2 hours, 2.2 hours, 2.4 hours, 2.6 hours, 2.8 hours, 3 hours, 3.2 hours, 3.4 hours, 3.6 hours, 3.8 hours or 4 hours, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0041] As a preferred technical solution of the present invention, in step S3, the drying temperature of PA66 is 90-110℃, for example, it can be 90℃, 92℃, 94℃, 96℃, 98℃, 100℃, 102℃, 104℃, 106℃, 108℃ or 110℃, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0042] In some optional embodiments, the drying time of PA66 is 6-10 hours, for example, 6 hours, 6.4 hours, 6.8 hours, 7.2 hours, 7.6 hours, 8 hours, 8.4 hours, 8.8 hours, 9.2 hours, 9.6 hours or 10 hours, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0043] In some optional embodiments, the mass ratio of the carrier resin, modified silica powder, and compatibilizer is (75-84.5):(15-22):(0.5-1.5), for example, it can be (75, 75.95, 76.9, 77.85, 78.8, 79.75, 80.7, 81.65, 82.6, 83.55, or 84.5):(15, 15.7, 16.4, 17.1, 17.8, 18.5, 19.2, 19.9, 20.6, 21.3, or 22):(0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, or 1.5), but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0044] The compatibilizer is Lotader® AX8900.

[0045] In some optional embodiments, the temperature of the extruder heating zone is 250-280°C, for example, 250°C, 253°C, 256°C, 259°C, 262°C, 265°C, 268°C, 271°C, 274°C, 277°C or 280°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0046] In some alternative embodiments, the screw rotation speed is 200-350 rpm, for example, 200 rpm, 215 rpm, 230 rpm, 245 rpm, 260 rpm, 275 rpm, 290 rpm, 305 rpm, 320 rpm, 335 rpm or 350 rpm, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0047] As a preferred technical solution of the present invention, in step S4, PA66 accounts for 90-97 wt% of the total amount of polyamide resin, for example, it can be 90 wt%, 90.7 wt%, 91.4 wt%, 92.1 wt%, 92.8 wt%, 93.5 wt%, 94.2 wt%, 94.9 wt%, 95.6 wt%, 96.3 wt%, or 97 wt%, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0048] In some optional embodiments, PA6 accounts for 3-10 wt% of the total amount of the polyamide resin matrix, for example, 3 wt%, 3.7 wt%, 4.4 wt%, 5.1 wt%, 5.8 wt%, 6.5 wt%, 7.2 wt%, 7.9 wt%, 8.6 wt%, 9.3 wt%, or 10 wt%, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0049] In some optional embodiments, the mass ratio of antioxidant 1098 to antioxidant 168 in the composite antioxidant is 1:(1-2), for example, it can be 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9 or 1:2, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0050] The lubricant is ethylene bis-stearamide or pentaerythritol stearate.

[0051] In some alternative embodiments, the drying temperature is 90-110°C, for example, 90°C, 92°C, 94°C, 96°C, 98°C, 100°C, 102°C, 104°C, 106°C, 108°C or 110°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0052] In some optional embodiments, the drying time is 6-8 hours, for example, 6 hours, 6.2 hours, 6.4 hours, 6.6 hours, 6.8 hours, 7 hours, 7.2 hours, 7.4 hours, 7.6 hours, 7.8 hours or 8 hours, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0053] In some alternative embodiments, the temperature of the extruder is 250-285°C, for example, 250°C, 253.5°C, 257°C, 260.5°C, 264°C, 267.5°C, 271°C, 274.5°C, 278°C, 281.5°C, or 285°C, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0054] In some alternative embodiments, the screw rotation speed is 300-400 rpm, for example, 300 rpm, 310 rpm, 320 rpm, 330 rpm, 340 rpm, 350 rpm, 360 rpm, 370 rpm, 380 rpm, 390 rpm or 400 rpm, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0055] In some optional embodiments, the vacuum degree of the mixing section is -0.09 to -0.06 MPa, for example, it can be -0.09 MPa, -0.087 MPa, -0.084 MPa, -0.081 MPa, -0.078 MPa, -0.075 MPa, -0.072 MPa, -0.069 MPa, -0.066 MPa, -0.063 MPa or -0.06 MPa, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0056] In some optional embodiments, the mass ratio of the polyamide resin matrix, modified silica powder derived from the interface buffer anchoring masterbatch, modified talc, composite antioxidant, lubricant, polytetrafluoroethylene micro powder, and chopped glass fiber is (55-75):(1.5-3.5):(1-5):(0.3-1):(0.2-0.5):(0.1-1):(15-25), for example, it can be (55, 57, 59, 61, 63, 65, 67, 69, 71, 73, or 75):(1.5, 1.7, 1.9, 2.1, 2.3, 2.5, 2.7, 2.9, 3.1, 3.3, or 3.5):(1, 1.4, 1.8, 2.2, 2.6, 3, 3). 4, 3.8, 4.2, 4.6 or 5: (0.3, 0.37, 0.44, 0.51, 0.58, 0.65, 0.72, 0.79, 0.86, 0.93 or 1): (0.2, 0.23, 0.26, 0.29, 0.32, 0.35, 0.38, 0.41, 0.44, 0.47 or 0.5): (0.1, 0.19, 0.28, 0.37, 0.46, 0.55, 0.64, 0.73, 0.82, 0.91 or 1): (15, 16, 17, 18, 19, 20, 21, 22, 23, 24 or 25), but not limited to the listed values; other unlisted values ​​within this range also apply.

[0057] In some optional embodiments, the temperature for circulating hot air drying of the composite material particles is 105-115°C, for example, 105°C, 106°C, 107°C, 108°C, 109°C, 110°C, 111°C, 112°C, 113°C, 114°C or 115°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0058] In some optional embodiments, the hot air drying time for the composite material particles is 8-12 hours, for example, 8 hours, 8.4 hours, 8.8 hours, 9.2 hours, 9.6 hours, 10 hours, 10.4 hours, 10.8 hours, 11.2 hours, 11.6 hours or 12 hours, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0059] In some optional embodiments, the temperature of the injection molding melt is 270-295°C, for example, it can be 270°C, 272.5°C, 275°C, 277.5°C, 280°C, 282.5°C, 285°C, 287.5°C, 290°C, 292.5°C or 295°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0060] In some alternative embodiments, the injection pressure is 80-120 MPa, for example, it can be 80 MPa, 84 MPa, 88 MPa, 92 MPa, 96 MPa, 100 MPa, 104 MPa, 108 MPa, 112 MPa, 116 MPa or 120 MPa, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0061] In some alternative embodiments, the temperature of the mold is 90-100°C, for example, it can be 90°C, 91°C, 92°C, 93°C, 94°C, 95°C, 96°C, 97°C, 98°C, 99°C or 100°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0062] In a second aspect, the present invention provides a wear-resistant and scratch-resistant nylon composite material, which is prepared according to the preparation method described in the first aspect.

[0063] The system described in this application is an interface modulation and stress dispersion system established around a polyamide matrix, a rigid reinforcing phase, and a surface stress-bearing region. Its purpose is not merely to increase the hardness of a certain component or reduce a certain friction parameter, but to make the stress, deformation, and interface response of the surface micro-region more coordinated when the material is scratched, thereby reducing the accumulation of surface damage caused by local abrupt changes.

[0064] Nano-silica initially exists as an inorganic core, possessing high rigidity and a small particle size. When incorporated into the polyamide system, it provides micro-regional compressive support in the scratching contact area, reducing the degree of surface indentation and plowing under sharp loads. After hydrolysis and condensation, methyltriethoxysilane and dimethyldiethoxysilane form a graft layer containing organosilicon structures on the silica surface. The structural units derived from methyltriethoxysilane have a high degree of condensation, contributing to the formation of a relatively stable outer framework; while the structural units derived from dimethyldiethoxysilane exhibit strong segmental flexibility, forming a transition layer between the inorganic core and the organic matrix. This transition layer helps reduce the abrupt change in interfacial modulus caused by direct exposure of rigid particles, preventing excessive load concentration around the particles and thus mitigating localized brittle responses during scratching. The experimental design employs a stepwise reaction method: first acidic hydrolysis, then condensation in neutral to weakly alkaline conditions, followed by the introduction of KH560. This method facilitates the gradual construction and stable bonding of the organosilicon layer to the silica surface, helps reduce the residue of free oligomeric siloxanes, and makes the resulting powder more suitable for subsequent melt blending.

[0065] After the introduction of KH560 in the second stage, it can continue to condense with the previously formed silanol-containing structure, resulting in a greater distribution of reactive groups on the outer layer of the particles. Furthermore, its epoxy functional groups can undergo ring-opening reactions with the polyamide end groups during subsequent melt processing, and form interfacial bonds with the amide groups in the polyamide segments through non-covalent interactions such as hydrogen bonding and dipole-dipole interactions. This helps improve the interfacial stability between the modified silica powder and the polyamide matrix. This outer reactive structure makes the modified silica powder not just a simple filler, but more like an interfacial regulating unit capable of forming a relatively stable interfacial interaction with the matrix. Consequently, the particles are less prone to detaching from the matrix under scratching stress and are less likely to form independent hard spots on the surface, helping to mitigate interfacial microvoids, microcracks, and the resulting enhanced light scattering. For polyamides, which are highly polar systems and sensitive to moisture and interfacial conditions, this outer anchoring effect can also improve the stability of the interfacial region during processing and use.

[0066] The use of interfacial buffer anchoring masterbatch further enhances these effects. Pre-dispersing the modified silica powder with PA66 and a compatibilizer improves the initial wetting of the particles in the resin and reduces the likelihood of secondary agglomeration during subsequent compounding. The reactive groups in Lotader® AX8900 enhance the coating and interfacial bonding of polymer segments around the particles, making the modified silica more easily and stably dispersed in the polyamide continuous phase. This pre-dispersion step aims not only to improve dispersion uniformity but also to facilitate the distribution of the modified silica around the matrix and reinforcing phases in the final composite system, thereby forming a more continuous interfacial transition region. Compared to directly adding inorganic particles to the total formulation, the masterbatch approach is more advantageous for controlling the consistency of the interfacial structure and processing stability.

[0067] In this system, modified talc powder does not merely serve as a common mineral filler. Talc itself has a lamellar structure, and after treatment with a silane coupling agent, its surface polarity and compatibility with polyamide are improved, making it easier to orient and distribute along the flow direction during melt flow and injection molding. When the surface of the part is scratched, this lamellar structure can form a relatively dispersed stress transmission path near the surface, spreading and diverting tangential loads, and reducing the shear strength borne by a single point in a local area. Simultaneously, the lamellar filler has a certain inhibitory effect on the propagation of interfacial microcracks, reducing the penetration of microcracks and the accumulation of microvoids around the reinforcing phase. When used in combination with modified silica powder, the former tends to provide planar stress dispersion and surface stability, while the latter tends to provide interfacial buffering, local support, and anchoring. Together, they act on the surface and interfacial regions most prone to instability during scratching.

[0068] Short-cut glass fibers primarily serve as a reinforcing skeleton and load-bearing component, maintaining good strength, rigidity, and wear resistance in the material. Since glass fibers are a relatively rigid reinforcing phase, the state of the surrounding interface significantly impacts the appearance under surface scratching conditions. In this application, the multiphase interface structure formed by modified silica powder, modified talc powder, and the polyamide matrix helps mitigate modulus abrupt changes in the region adjacent to the glass fibers, reduces localized stress concentration at the fiber ends or near the surface, and minimizes scratches and whitening caused by fiber floating, pull-out, and debonding around the fibers. A small amount of PA6 and PA66 compounded together can improve melt flow, interface wetting, and the continuity of the molded surface to some extent, making it easier for the multiphase components to form a relatively uniform surface structure. The composite antioxidant is used to reduce the thermo-oxidative degradation of polyamide during processing, maintaining molecular chain integrity and interfacial bonding. The lubricant and polytetrafluoroethylene micropowder are mainly used to regulate processing and initial friction behavior, but their dosage is controlled to avoid excessive enrichment of the surface lubricant phase, which could affect interfacial stability.

[0069] This application addresses several consecutive stages in the scratch damage formation process: firstly, reducing the tendency for instantaneous surface indentation and ploughing; secondly, mitigating stress abrupt changes between the inorganic phase and polyamide; further reducing the risk of interfacial debonding, microvoids, and microcrack propagation; and finally, minimizing whitening caused by increased surface discontinuities. The modified silica powder, interfacial buffering and anchoring masterbatch, modified talc, and glass fiber do not function independently, but rather work synergistically at the levels of surface support, interfacial buffering, stress dispersion, and structural stability. This allows the material to maintain wear resistance and mechanical properties while exhibiting good scratch resistance and appearance retention.

[0070] Compared with the prior art, the beneficial effects of the present invention are as follows: This application utilizes a combination of modified silica powder, modified talc powder, and chopped glass fiber to maintain the wear resistance and mechanical support of polyamide composite materials while helping to reduce residual scratches and surface whitening after scratching.

[0071] Modified silica powder can form a relatively stable interface transition between the inorganic phase and the polyamide matrix, reducing local stress concentration under scratch load, thereby helping to suppress interface debonding, microvoids and microcracks.

[0072] Modified talc has a certain dispersing effect on surface shear stress, while modified silica powder provides micro-area support and interface buffer. Together with glass fiber, the two help reduce the enhanced light scattering caused by surface structural instability and improve the scratch whitening phenomenon.

[0073] Introducing modified silica powder by using interface buffer anchoring masterbatch can improve its dispersion in polyamide systems and help reduce the adverse effects of component migration or precipitation on surface appearance stability. Attached Figure Description

[0074] Figure 1 This is a physical image of the wear-resistant and scratch-resistant nylon composite material prepared in Example 1 of the present invention. Detailed Implementation

[0075] The technical solutions of the present invention will be described in detail below with reference to specific embodiments and accompanying drawings. The embodiments described herein are specific implementations of the present invention, used to illustrate the concept of the present invention; these descriptions are explanatory and exemplary, and should not be construed as limiting the implementation methods or the scope of protection of the present invention. In addition to the embodiments described herein, those skilled in the art can employ other obvious technical solutions based on the content disclosed in the claims and specification of this application. These technical solutions include any obvious substitutions and modifications made to the embodiments described herein.

[0076] The chemical reagents used in the embodiments and comparative examples of this invention are all commercially available products and have not undergone further purification or processing.

[0077] The talc powder used in the embodiments and comparative examples of this invention has an equivalent flake diameter D50 of 1-3 μm and an aspect ratio of 5-30.

[0078] Example 1 This embodiment provides a wear-resistant and scratch-resistant nylon composite material and its preparation method. The preparation method specifically includes the following steps: S1: 50 nm nano-sized silica particles are dispersed in a mixed solvent to obtain a dispersion. The volume ratio of ethanol to deionized water in the mixed solvent is 80:20, and the mass-to-volume ratio of nano-silica to the mixed solvent is 1 g:25 mL. The pH of the dispersion is adjusted to 4.5 using an 8% (w / w) diacetic acid solution. Methyltriethoxysilane and dimethyldiethoxysilane are then added to obtain reaction solution A, where the molar ratio of methyltriethoxysilane to dimethyldiethoxysilane is 50:20. The molar ratio of deionized water to the total number of hydrolyzable alkoxy groups in methyltriethoxysilane and dimethyldiethoxysilane in the mixed solution is 4.0. :1; Hydrolysis and condensation were carried out at 50℃ for 1.2h, and the pH was adjusted to 7.2 with a 4% ammonia solution. The reaction was continued at 60℃ for 2.5h to obtain reaction solution B. KH560 ethanol solution was added, wherein the molar ratio of KH560 to the total amount of methyltriethoxysilane and dimethyldiethoxysilane was 25:60. The pH was adjusted to 6.0 with a 4% diacetic acid solution, and the reaction was continued at 50℃ for 1.5h. After the reaction was completed, the product was separated by centrifugation, washed three times with ethanol, and then washed four times with n-hexane. The product was vacuum dried at 100℃ for 9h, pulverized, and modified silica powder was obtained. S2: Prepare a 1.2% (w / w) aqueous alcohol solution of silane coupling agent KH550, wherein the volume ratio of ethanol to deionized water in the aqueous alcohol solution of silane coupling agent is 70:30. Adjust the pH to 4.8 using a first acetic acid solution. Pre-hydrolyze at room temperature for 35 min to obtain a modified solution. Add talc powder to the modified solution, wherein the mass-volume ratio of talc powder to the modified solution is 1 g:12 mL. Stir at 55 °C for 1.8 h. After solid-liquid separation, dry at 125 °C for 3 h to obtain modified talc powder. S3: PA66 was vacuum dried at 100℃ for 9 hours to obtain the carrier resin. The carrier resin, modified silica powder and compatibilizer Lotader® AX8900 were mixed at a mass ratio of 80:20:1.0 to obtain a mixture. The mixture was added to a twin-screw extruder, where the extruder heating zone temperature was 260℃ and the screw speed was 300 rpm. After melt extrusion, water cooling pelletizing and drying, the interface buffer anchoring masterbatch was obtained. S4: A mixture of polyamide resin matrix (PA66 comprising 95 wt% of the total polyamide resin matrix and PA6 comprising 5 wt% of the total polyamide resin matrix), interface buffer anchoring masterbatch, modified talc powder, composite antioxidant (composed of antioxidant 1098 and antioxidant 168 in a mass ratio of 1:1.5), lubricant ethylene bis-stearamide, and polytetrafluoroethylene micro powder is prepared and dried at 100℃ for 7 hours before being added through the main feed port of a twin-screw extruder. Simultaneously, chopped glass fibers are added through the side feed port. The extrusion temperature is set to 270℃, the screw speed to 350 rpm, and the mixing section is under vacuum. The pressure was controlled at -0.08 MPa, and composite material particles were obtained through extrusion and pelletizing. The mass ratio of polyamide resin matrix, modified silica powder derived from interface buffer anchoring masterbatch, modified talc powder, composite antioxidant, lubricant, polytetrafluoroethylene micro powder, and chopped glass fiber was 60:2.5:3:0.8:0.4:0.5:20. The composite material particles were dried with circulating hot air at 110℃ for 10 hours, and then molded on an injection molding machine. The melt temperature was controlled at 280℃, the injection pressure at 100 MPa, and the mold temperature at 95℃, ultimately yielding the desired product. Figure 1 The wear-resistant and scratch-resistant nylon composite material shown.

[0079] Example 2 This embodiment provides a wear-resistant and scratch-resistant nylon composite material and its preparation method. The preparation method specifically includes the following steps: S1: 30 nm nano-silica particles are dispersed in a mixed solvent to obtain a dispersion. The volume ratio of ethanol to deionized water in the mixed solvent is 70:30, and the mass-volume ratio of nano-silica to the mixed solvent is 1 g:10 mL. The pH of the dispersion is adjusted to 5 using a 5% (w / w) diacetic acid solution. Methyltriethoxysilane and dimethyldiethoxysilane are added to obtain reaction solution A, where the molar ratio of methyltriethoxysilane to dimethyldiethoxysilane is 30:35. The molar ratio of deionized water to the total number of hydrolyzable alkoxy groups in methyltriethoxysilane and dimethyldiethoxysilane in the mixed solution is 1:1. The mixture was hydrolyzed and condensed at 40℃ for 0.5 h, and the pH was adjusted to 6.5 with a 1% ammonia solution. The reaction was continued at 70℃ for 3 h to obtain reaction solution B. KH560 ethanol solution was added, wherein the molar ratio of KH560 to the total amount of methyltriethoxysilane and dimethyldiethoxysilane was 10:95. The pH was adjusted to 5.5 with a 1% diacetic acid solution, and the reaction was continued at 40℃ for 2 h. After the reaction was completed, the mixture was centrifuged, washed twice with ethanol, and then washed three times with n-hexane. The product was vacuum dried at 80℃ for 6 h, pulverized, and then the modified silica powder was obtained. S2: Prepare a 0.5% (w / w) aqueous alcohol solution of silane coupling agent KH560, wherein the volume ratio of ethanol to deionized water in the aqueous alcohol solution of silane coupling agent is 60:40. Adjust the pH to 4 using a first acetic acid solution. Pre-hydrolyze at room temperature for 20 min to obtain a modified solution. Add talc powder to the modified solution, wherein the mass-volume ratio of talc powder to the modified solution is 1 g:5 mL. Stir at 40 °C for 1 h. After solid-liquid separation, dry at 110 °C for 2 h to obtain modified talc powder. S3: PA66 was vacuum dried at 90℃ for 6 hours to obtain the carrier resin. The carrier resin, modified silica powder and compatibilizer Lotader® AX8900 were mixed at a mass ratio of 75:22:0.5 to obtain a mixture. The mixture was added to a twin-screw extruder, where the extruder heating zone temperature was 250℃ and the screw speed was 200rpm. After melt extrusion, water cooling pelletizing and drying, the interface buffer anchoring masterbatch was obtained. S4: Mix the polyamide resin matrix (of which PA66 accounts for 90wt% of the total polyamide resin matrix and PA6 accounts for 10wt% of the total polyamide resin matrix), interface buffer anchoring masterbatch, modified talc powder, composite antioxidant (composed of antioxidant 1098 and antioxidant 168 in a 1:1 mass ratio), lubricant pentaerythritol stearate, and polytetrafluoroethylene micro powder, dry at 90℃ for 6 hours, and then add it through the main feed port of a twin-screw extruder; simultaneously, add chopped glass fiber through the side feed port; set the extrusion temperature to 250℃, screw speed to 300rpm, and vacuum degree in the mixing section controlled at - The composite material particles were obtained by extrusion and pelletizing at a pressure of 0.06 MPa. The mass ratio of polyamide resin, modified silica powder derived from interface buffer anchoring masterbatch, modified talc, composite antioxidant, lubricant, polytetrafluoroethylene micro powder, and chopped glass fiber was 55:3.5:1:0.3:0.2:0.1:25. The composite material particles were dried with circulating hot air at 105℃ for 8 hours, and then molded on an injection molding machine. The melt temperature was controlled at 270℃, the injection pressure at 80 MPa, and the mold temperature at 90℃, finally obtaining a wear-resistant and scratch-resistant nylon composite material.

[0080] Example 3 This embodiment provides a wear-resistant and scratch-resistant nylon composite material and its preparation method. The preparation method specifically includes the following steps: S1: 80 nm nano-silica particles are dispersed in a mixed solvent to obtain a dispersion, wherein the volume ratio of ethanol to deionized water in the mixed solvent is 95:5, and the mass-volume ratio of nano-silica to the mixed solvent is 1 g:15 mL; the pH of the dispersion is adjusted to 4 using a 10% (w / w) acetic acid solution, and methyltriethoxysilane and dimethyldiethoxysilane are added to obtain reaction solution A, wherein the molar ratio of methyltriethoxysilane to dimethyldiethoxysilane is 60:10, and the molar ratio of deionized water to the total number of hydrolyzable alkoxy groups in methyltriethoxysilane and dimethyldiethoxysilane in the mixed solution is 2. The reaction mixture was hydrolyzed and condensed at 60℃ for 1.5 h. The pH was adjusted to 7.5 with a 2% ammonia solution, and the reaction was continued at 50℃ for 2 h to obtain reaction solution B. KH560 ethanol solution was added, wherein the molar ratio of KH560 to the total amount of methyltriethoxysilane and dimethyldiethoxysilane was 30:40. The pH was adjusted to 6.3 with a 5% diacetic acid solution, and the reaction was continued at 55℃ for 1 h. After the reaction was completed, the product was separated by centrifugation, washed three times with ethanol, and then washed five times with n-hexane. The product was vacuum dried at 110℃ for 10 h, pulverized, and then modified silica powder was obtained. S2: Prepare a 1.0% (w / w) aqueous alcohol solution of silane coupling agent KH560, wherein the volume ratio of ethanol to deionized water in the aqueous alcohol solution of silane coupling agent is 80:20. Adjust the pH to 4.2 using a first acetic acid solution. Pre-hydrolyze at room temperature for 25 min to obtain a modified solution. Add talc powder to the modified solution, wherein the mass-volume ratio of talc powder to the modified solution is 1 g:8 mL. Stir at 45℃ for 1.2 h. After solid-liquid separation, dry at 115℃ for 4 h to obtain modified talc powder. S3: PA66 was vacuum dried at 110℃ for 10h to obtain the carrier resin. The carrier resin, modified silica powder and compatibilizer Lotader® AX8900 were mixed at a mass ratio of 84.5:15:1.5 to obtain a mixture. The mixture was added to a twin-screw extruder, where the extruder heating zone temperature was 280℃ and the screw speed was 350rpm. After melt extrusion, water cooling pelletizing and drying, the interface buffer anchoring masterbatch was obtained. S4: A mixture of polyamide resin matrix (PA66 comprising 97 wt% of the total polyamide resin matrix and PA6 comprising 3 wt% of the total polyamide resin matrix), interface buffer anchoring masterbatch, modified talc, composite antioxidant (composed of antioxidant 1098 and antioxidant 168 in a mass ratio of 1:2), lubricant pentaerythritol stearate, and polytetrafluoroethylene micropowder is prepared and dried at 110℃ for 8 hours before being added through the main feed port of a twin-screw extruder. Simultaneously, chopped glass fibers are added through the side feed port. The extrusion temperature is set to 285℃, the screw speed to 400 rpm, and the vacuum level in the mixing section is controlled at [value missing]. -0.09MPa, through extrusion and pelletizing, composite material particles were obtained; the mass ratio of polyamide resin matrix, modified silica powder derived from interface buffer anchoring masterbatch, modified talc powder, composite antioxidant, lubricant, polytetrafluoroethylene micro powder and chopped glass fiber was 75:1.5:5:1:0.5:1:15. The composite material particles were dried with circulating hot air at 115℃ for 12h, and then molded on an injection molding machine. The injection molding melt temperature was controlled at 295℃, the injection pressure at 120MPa, and the mold temperature at 100℃, finally obtaining wear-resistant and scratch-resistant nylon composite material.

[0081] Example 4 This embodiment provides a wear-resistant and scratch-resistant nylon composite material and its preparation method. The preparation method specifically includes the following steps: S1: 60 nm nano-silica particles are dispersed in a mixed solvent to obtain a dispersion, wherein the volume ratio of ethanol to deionized water in the mixed solvent is 85:15, and the mass-volume ratio of nano-silica to the mixed solvent is 1 g:30 mL. The pH of the dispersion is adjusted to 4.8 using a 7% (w / w) diacetic acid solution. Methyltriethoxysilane and dimethyldiethoxysilane are added to obtain reaction solution A, wherein the molar ratio of methyltriethoxysilane to dimethyldiethoxysilane is 40:25, and the molar ratio of deionized water to the total number of hydrolyzable alkoxy groups in methyltriethoxysilane and dimethyldiethoxysilane in the mixed solution is 5. 0:1; hydrolysis and condensation at 55℃ for 1.0 h, pH adjusted to 6.8 with 5% ammonia solution, reaction continued at 65℃ for 2.8 h to obtain reaction solution B, KH560 ethanol solution was added, wherein the molar ratio of KH560 to the total amount of methyltriethoxysilane and dimethyldiethoxysilane was 15:80, pH adjusted to 5.8 with 3% diacetic acid solution, reaction continued at 45℃ for 1.8 h; after the reaction was completed, centrifugation was performed, washing twice with ethanol and then four times with n-hexane; the product was vacuum dried at 90℃ for 8 h, pulverized to obtain modified silica powder; S2: Prepare a 1.5% (w / w) aqueous alcohol solution of silane coupling agent KH550, wherein the volume ratio of ethanol to deionized water in the aqueous alcohol solution of silane coupling agent is 75:25. Adjust the pH to 5 using a first acetic acid solution, pre-hydrolyze at room temperature for 40 min to obtain a modified solution, add talc powder to the modified solution, wherein the mass-volume ratio of talc powder to the modified solution is 1 g:15 mL, stir at 60℃ for 2 h, and after solid-liquid separation, dry at 130℃ for 3.5 h to obtain modified talc powder; S3: PA66 was vacuum dried at 95℃ for 8 hours to obtain the carrier resin. The carrier resin, modified silica powder and compatibilizer Lotader® AX8900 were mixed at a mass ratio of 82:18:1.2 to obtain a mixture. The mixture was added to a twin-screw extruder, where the extruder heating zone temperature was 270℃ and the screw speed was 250rpm. After melt extrusion, water cooling pelletizing and drying, the interface buffer anchoring masterbatch was obtained. S4: A mixture of polyamide resin matrix (PA66 comprising 92 wt% of the total polyamide resin matrix and PA6 comprising 8 wt% of the total polyamide resin matrix), interface buffer anchoring masterbatch, modified talc powder, composite antioxidant (composed of antioxidant 1098 and antioxidant 168 in a mass ratio of 1:1.8), lubricant ethylene bis-stearamide, and polytetrafluoroethylene micro powder is prepared and dried at 95°C for 7.5 hours before being added through the main feed port of a twin-screw extruder. Simultaneously, chopped glass fibers are added through the side feed port. The extrusion temperature is set to 260°C, the screw speed to 320 rpm, and the vacuum level in the mixing section is controlled at [value missing]. -0.07MPa, through extrusion and pelletizing, composite material particles were obtained; the mass ratio of polyamide resin matrix, modified silica powder derived from interface buffer anchoring masterbatch, modified talc powder, composite antioxidant, lubricant, polytetrafluoroethylene micro powder and chopped glass fiber was 70:2.0:4:0.6:0.3:0.8:22. The composite material particles were dried with circulating hot air at 112℃ for 9 hours, and then molded on an injection molding machine. The melt temperature of the injection molding process was controlled at 290℃, the injection pressure at 90MPa, and the mold temperature at 92℃, finally obtaining a wear-resistant and scratch-resistant nylon composite material.

[0082] Comparative Example 1 This comparative example provides a wear-resistant and scratch-resistant nylon composite material and its preparation method. The difference from Example 1 is that step S1 is omitted and unmodified nano-silica is used directly in S4. Other operation steps and process parameters are exactly the same as in Example 1.

[0083] Comparative Example 2 This comparative example provides a wear-resistant and scratch-resistant nylon composite material and its preparation method. The difference from Example 1 is that KH560 ethanol solution is not added in step S1, while other operation steps and process parameters are exactly the same as in Example 1.

[0084] Comparative Example 3 This comparative example provides a wear-resistant and scratch-resistant nylon composite material and its preparation method. The difference from Example 1 is that step S3 is omitted and modified silica powder is directly added in S4. Other operation steps and process parameters are exactly the same as in Example 1.

[0085] Comparative Example 4 This comparative example provides a wear-resistant and scratch-resistant nylon composite material and its preparation method. The difference from Example 1 is that step S2 is omitted, and unmodified talc is used directly instead of modified talc in S4. Other operation steps and process parameters are exactly the same as in Example 1.

[0086] The wear-resistant and scratch-resistant nylon composite materials of Examples 1-4 and Comparative Examples 1-4 were subjected to performance tests, and the specific procedures are as follows: The composite material particles obtained in the above embodiments and comparative examples were injection molded to prepare test plate samples of the same size. After acclimatizing to humidity for 48 hours under standard environmental conditions (23°C, 50%RH), the following performance tests were performed: Scratch resistance and whitening test: Referring to the PV3952 standard, a cross-scratch test was performed on the surface of the flat sample using a scratch tester. The scratch load was set to 10N, and the scratch speed to 100mm / s. The difference in lightness value L between the scratched and unscratched areas was measured using a spectrophotometer, and the lightness change value ΔL was calculated. The smaller the ΔL value, the better the scratch resistance and whitening performance of the material surface.

[0087] Anti-penetration performance test: For the samples that have completed the scratch resistance test, a laser confocal microscope was used to perform a three-dimensional morphological scan of the scratched area on the surface, and the maximum depth (μm) of the residual scratch was measured. The smaller the residual scratch depth, the stronger the anti-penetration and stress dispersion ability of the micro-area of ​​the material surface.

[0088] Damp-heat aging stability test: The plate sample was placed in a constant temperature and humidity chamber and aged at 85℃ and 85%RH for 168 hours. After aging, it was removed and allowed to recover under standard environmental conditions for 4 hours. The change in brightness ΔL after aging was then measured again according to the scratch resistance and whitening test method described above. The smaller the increase in ΔL compared with that before aging, the better the retention of the material's surface structure and interface state, and the better the surface structure's resistance to damp heat and long-term stability.

[0089] Wear resistance test: The Taber abrasion tester was used to test the wear of the flat plate sample. The mass loss or wear volume under the specified load and number of revolutions was recorded. The smaller the value, the better the wear resistance of the material.

[0090] The test results are shown in Table 1.

[0091] Table 1. Test results of wear-resistant and scratch-resistant nylon composite materials in Examples 1-4 and Comparative Examples 1-4

[0092] As can be seen from the test results of Example 1 and Comparative Example 1 in Table 1, when unmodified nano-silica is used to replace modified silica powder, the surface organosilicon graft layer and outer reactive structure formed by methyltriethoxysilane, dimethyldiethoxysilane and KH560 are lacking. As a result, the wettability and dispersion stability of nano-silica in the polyamide system are worse, and there is a lack of effective interfacial transition and anchoring effect between it and the polyamide matrix. During the scratching process, localized hard spots and stress concentration areas are more likely to form around the particles, and interface debonding, microvoids, and microcracks are more likely to occur and expand, thus increasing the change in brightness. At the same time, due to insufficient compressive support and interface buffering in the surface micro-area, plowing and particle pull-out are more likely to occur under the action of the scratching needle, resulting in an increase in the depth of residual scratches. After wet heat aging, the interface between unmodified particles and the matrix is ​​more susceptible to moisture and further weakened, leading to a decrease in the stability of the surface structure. Therefore, the change in brightness after aging also increases. Since unmodified nano-silica is used instead of modified silica powder, the bonding and dispersion stability between the powder and the polyamide matrix are poor, making it easy to form localized hard spots and interface debonding during friction, thus increasing the wear and deteriorating the wear resistance.

[0093] As can be seen from the test results of Example 1 and Comparative Example 2 in Table 1, KH560 was not added during the preparation of modified silica powder. Although the organosilicon buffer layer formed by methyltriethoxysilane and dimethyldiethoxysilane was still retained, the outer epoxy reactive structure was lacking. The interfacial bonding between the particles and the polyamide matrix mainly relied on physical adsorption and weak polarity, and the degree of interfacial anchoring was lower than that of Example 1. During the scratching process, this type of interface is more prone to local slippage and debonding, resulting in an increase in surface discontinuous structures and enhanced light scattering, thus increasing its brightness change value. At the same time, due to the lack of reactive structures in the outer layer, the stress transmission around the particles is not stable enough, making it more prone to local plastic deformation and ploughing damage under the scratching load, thus increasing the depth of residual scratches. After wet heat aging, the interface lacking reactive anchoring is more susceptible to the effects of moisture and heat, leading to further relaxation and an increase in the brightness change value after aging. Since KH560 was not introduced, the outer layer of the modified silica powder lacks structures that can form partial reactions or strong interfacial interactions with polyamide, weakening the interfacial anchoring effect, thus increasing the wear and deteriorating the wear resistance.

[0094] As can be seen from the test results of Example 1 and Comparative Example 3 in Table 1, the preparation step of the interface buffer anchoring masterbatch was omitted, and the modified silica powder was directly added to the system in the final blending stage. Although the particle surface still has a modified structure, in the multiphase high-filling system where glass fiber, talc and polyamide coexist, direct feeding is not conducive to the full wetting and uniform pre-dispersion of modified silica, and it is more likely to cause local agglomeration and uneven distribution. Therefore, during the scratching process, uneven stress points are easily formed in local agglomerated areas, and stress concentration and structural instability are more likely to occur in the surface micro-areas, thus increasing the change in lightness value. At the same time, the damage to the surface continuity caused by agglomerated particles weakens the anti-ploughing ability of micro-areas, making scratches easier to deepen, thus increasing the depth of residual scratches. After humid heat aging, due to the uneven distribution of the interface, weak interface areas are more likely to become unstable, and the scratch resistance of the material surface decreases, thus increasing the change in lightness value after aging. Since the preparation step of interface buffer anchoring masterbatch is omitted and modified silica powder is added directly, the dispersion uniformity of the powder in the polyamide system decreases, local wear is aggravated during friction, thus increasing the wear amount and deteriorating the wear resistance.

[0095] As can be seen from the test results of Example 1 and Comparative Example 4 in Table 1, although the modified silica and interface buffer anchoring masterbatch system are retained when unmodified talc is used instead of modified talc, the interface compatibility between the talc surface and the polyamide matrix is ​​poor after the lack of silane coupling agent treatment. The wetting and bonding of the sheet filler in the matrix is ​​insufficient, making it difficult to fully exert the dispersion and transmission of stress. During the scratching process, interfacial slippage and localized debonding are more likely to occur around unmodified talc, leading to enhanced light scattering on the surface and thus an increased change in lightness. At the same time, the dispersing effect of the flake filler on the scratching load is weakened, and the surface is more prone to localized plastic flow and ploughing damage, thereby increasing the depth of residual scratches. After hydrothermal aging, the interface around the talc is more likely to be further weakened in the hydrothermal environment, resulting in decreased surface stability and an increased change in lightness after aging. Because unmodified talc is used instead of modified talc, the interfacial compatibility and stress dispersion stability between the flake filler and the polyamide matrix decrease, the wear loss increases, and the wear resistance deteriorates.

[0096] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A wear-resistant and scratch-resistant nylon composite material, characterized in that, It includes a polyamide resin matrix, modified silica powder, modified talc powder, composite antioxidant, lubricant, polytetrafluoroethylene micro powder, and chopped glass fiber; The modified silica powder is introduced into the nylon composite material in the form of an interface buffer anchoring masterbatch, which is prepared by melt extrusion of PA66, modified silica powder and compatibilizer. The mass ratio of the polyamide resin matrix, modified silica powder, modified talc powder, composite antioxidant, lubricant, polytetrafluoroethylene micro powder and chopped glass fiber is (55-75):(1.5-3.5):(1-5):(0.3-1):(0.2-0.5):(0.1-1):(15-25).

2. The wear-resistant and scratch-resistant nylon composite material according to claim 1, characterized in that, The polyamide resin matrix includes PA66 and PA6, wherein PA66 accounts for 90-97 wt% of the total polyamide resin matrix and PA6 accounts for 3-10 wt% of the total polyamide resin matrix.

3. The wear-resistant and scratch-resistant nylon composite material according to claim 1, characterized in that, The composite antioxidant is composed of antioxidant 1098 and antioxidant 168 in a mass ratio of 1:(1-2); the lubricant is ethylene bis-stearamide or pentaerythritol stearate.

4. The wear-resistant and scratch-resistant nylon composite material according to claim 1, characterized in that, The modified silica powder is prepared by hydrolysis and condensation reaction of nano silica, methyltriethoxysilane, dimethyldiethoxysilane and KH560.

5. The wear-resistant and scratch-resistant nylon composite material according to claim 1, characterized in that, The compatibilizer is Lotader® AX8900.

6. A method for preparing a wear-resistant and scratch-resistant nylon composite material as described in any one of claims 1-5, characterized in that, The preparation method includes: S1: Nano-silica is dispersed in a mixed solvent to obtain a dispersion; the pH of the dispersion is adjusted with a first acetic acid solution, and methyltriethoxysilane and dimethyldiethoxysilane are added to obtain reaction solution A. After hydrolysis and condensation, the pH is adjusted with an ammonia solution and the reaction continues to obtain reaction solution B; KH560 ethanol solution is added to reaction solution B, the pH is adjusted with a second acetic acid solution and the reaction continues; after the reaction is completed, modified silica powder is obtained by centrifugation, washing, drying and pulverizing. S2: After adjusting the pH of the silane coupling agent aqueous alcohol solution, pre-hydrolyze it to obtain a modified solution, add talc powder for surface treatment, and obtain modified talc powder after solid-liquid separation and drying. S3: PA66, modified silica powder and compatibilizer are mixed and added to a twin-screw extruder. After melt extrusion, water cooling pelletizing and drying, interface buffer anchoring masterbatch is obtained. S4: Polyamide resin matrix, interface buffer anchoring masterbatch, modified talc powder, composite antioxidant, lubricant and polytetrafluoroethylene micro powder are mixed and added through the main feed port of a twin-screw extruder. At the same time, chopped glass fiber is added through the side feed port. After melt extrusion, pelletizing and injection molding, wear-resistant and scratch-resistant nylon composite material is obtained.

7. The method for preparing a wear-resistant and scratch-resistant nylon composite material according to claim 6, characterized in that, In S1, the particle size of the nano-silica is 30-80 nm; the volume ratio of ethanol to deionized water in the mixed solvent is (70-95):(30-5), and the mass-volume ratio of nano-silica to the mixed solvent is 1 g:(10-30) mL.

8. The method for preparing a wear-resistant and scratch-resistant nylon composite material according to claim 6, characterized in that, In S1, the molar ratio of methyltriethoxysilane to dimethyldiethoxysilane is (30-60):(10-35), and the molar ratio of deionized water to the total amount of hydrolyzable alkoxy groups in methyltriethoxysilane and dimethyldiethoxysilane in the mixed solution is (1.5-5.0):1; the molar ratio of KH560 to the total amount of methyltriethoxysilane and dimethyldiethoxysilane is (10-30):(40-95).

9. The method for preparing a wear-resistant and scratch-resistant nylon composite material according to claim 6, characterized in that, In step S1, the pH of the dispersion is adjusted to 4-5 using a 5-10% (w / w) first acetic acid solution. Methyltriethoxysilane and dimethyldiethoxysilane are added to obtain reaction solution A, which is then hydrolyzed and condensed at 40-60°C for 0.5-1.5 h. The pH is then adjusted to 6.5-7.5 using a 1-5% (w / w) ammonia solution, and the reaction is continued at 50-70°C for 2-3 h to obtain reaction solution B. After adding KH560 ethanol solution to the reaction solution B, the pH of the system is adjusted to 5.5-6.3 using a 1-5% (w / w) diacetic acid solution, and the reaction is continued at 40-55℃ for 1-2 hours.

10. The method for preparing a wear-resistant and scratch-resistant nylon composite material according to claim 6, characterized in that, In S2: the silane coupling agent is KH550 or KH560, the mass fraction of the silane coupling agent aqueous alcohol solution is 0.5-1.5%, wherein the volume ratio of ethanol to deionized water is (60-80):(40-20), the pre-hydrolysis time is 20-40 min, and the mass-volume ratio of talc to modified solution is 1 g:(5-15) mL; In S3, the mass ratio of PA66, modified silica powder and compatibilizer is (75-84.5):(15-22):(0.5-1.5).

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