Polyamide composite material, method for producing same, and use thereof

Abstract

The application discloses a kind of polyamide composite material and its preparation method and application, it is related to the technical field of plastic.A kind of polyamide composite material includes the following weight parts of component: first PA resin 48-72 parts;Nylon composition 9-26 parts;Nylon composition includes second PA resin and glass fiber, the number ratio of glass fiber in nylon composition is 90-100% in the distribution of the retained length of 500 μm below, the number ratio of glass fiber retained length is 0-10% in the distribution of 500 μm above;The relative viscosity of first PA resin is not less than 2.7, and the relative viscosity of nylon composition is not less than 2.4.The polyamide composite material with excellent surface treatment performance and mechanical properties is prepared by adding nylon composition in first PA resin in the application, is suitable for being used for preparing automobile parts, especially suitable for functional parts needing surface treatment or using special appearance requirements.

Description

Technical Field

[0001] This invention relates to the field of plastics, and more particularly to a polyamide composite material, its preparation method, and its application. Background Technology

[0002] Polyamide (nylon, PA) is a class of semi-crystalline thermoplastic engineering plastics with balanced properties. It is widely used in the automotive, electronics, mechanical transmission, and home appliance industries due to its high strength and toughness, excellent wear resistance and self-lubrication, good oil, fuel, and chemical resistance, electrical insulation, and good processability (injection molding, extrusion, and fiber spinning). Furthermore, it can be modified to improve heat resistance and dimensional stability through glass fiber reinforcement, flame retardancy, toughening, and hydrolysis resistance. Currently, the recycling of single-reinforced nylon materials mainly involves chemical recycling and physical recycling. Chemical recycling primarily involves depolymerizing waste nylon to obtain monomers for reuse, while physical recycling mainly involves mechanical crushing and recycling, followed by blending to extend the lifespan of nylon materials in the market.

[0003] However, the chemical recycling process for nylon is complex and energy-intensive, posing a challenge for large-scale production; while physical recycling methods, due to the secondary or multiple processing heat history, can lead to a decrease in the mechanical strength of the material, thus failing to be widely recycled and used in everyday plastic parts.

[0004] Therefore, there is an urgent need in this field to find a recycling pathway and application for single-reinforced nylon, which can extend the life cycle of nylon materials on the one hand, and broaden the application of recycled PCR nylon materials on the other hand, so as to meet the needs of green and environmentally friendly use of materials. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a polyamide composite material, its preparation method, and its applications. This invention involves adding a nylon composition to PA resin to obtain a polyamide composite material with both excellent surface treatment properties and mechanical properties. It is suitable for manufacturing automotive parts, and particularly applicable to functional parts requiring surface treatment or special appearance specifications.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a polyamide composite material comprising the following components in parts by weight: First, 48-72 parts of PA resin; 9-26 parts of nylon composition; 0.5-3 parts of additives; The nylon composition comprises a second PA resin and glass fibers, wherein the proportion of glass fibers with a retention length distribution below 500 μm in the nylon composition is 90-100%, and the proportion of glass fibers with a retention length distribution above 500 μm is 0-10%. The relative viscosity of the first PA resin is not less than 2.7, and the relative viscosity of the nylon composition is not less than 2.4.

[0007] During the pre-extrusion process of the nylon composition, the glass fiber raw material is sheared by the screw and distributed in the matrix of plastic particles. By controlling the retention length of 90-100% of the glass fibers to be below 500 μm, the glass fibers can be well dispersed on the material surface, resulting in better surface treatment effect. This is beneficial to improving the surface treatment performance of the composite material, giving the composite material excellent painting and electroplating effects.

[0008] It should be noted that the glass fiber retention length distribution in the nylon composition is quite unique. After the nylon composition undergoes a second heat treatment with the first PA resin and additives following the initial heat treatment, adjusting the distribution range of the glass fiber retention length can improve its dispersibility on the material surface, thereby enhancing the surface treatment performance of the composite material. If the glass fiber retention length distribution range is inappropriate, even if shorter glass fibers are obtained after the second heat treatment, they cannot be well dispersed on the material surface, resulting in a reduction in the surface treatment performance of the composite material.

[0009] Test method for glass fiber retention length in polyammonium composites and nylon compositions: According to ISO 3451-2019, the polyammonium composite or nylon composition is placed in a muffle furnace at 650±25℃ for 2h. After cooling, the ash obtained is collected. At least 300 fibers are randomly selected under an optical microscope, and their length is measured using image analysis software. The distribution of glass fiber retention length is then statistically analyzed.

[0010] The relative viscosity test method is as follows: Referring to ISO 1628-2019 (Method for determination of viscosity of dilute solutions of polymers), the relative viscosity of polyamide is determined using the capillary viscometer method. The polyamide sample to be tested is dissolved in a 96% sulfuric acid solution at a test temperature of 25°C to prepare a polymer solution of the specified concentration. Under constant temperature conditions, the outflow time of the polymer solution and the pure solvent between the marks in the capillary viscometer is measured. The relative viscosity of the sample is calculated as the ratio of the solution outflow time to the solvent outflow time.

[0011] Preferably, the proportion of glass fibers with a retention length distribution in the range of 10-299 μm in the nylon composition is 90-100%, and the proportion of glass fibers with a retention length distribution in the range of 300-500 μm is 0-10%.

[0012] Preferably, the proportion of glass fibers with a retention length distribution in the range of 10-199 μm in the nylon composition is 80-100%, and the proportion of glass fibers with a retention length distribution in the range of 200-300 μm is 0-20%.

[0013] This invention controls the distribution of the retained length of glass fibers in the nylon composition within the above-mentioned range, so that short glass fibers can be better distributed on the surface of the part during subsequent injection molding, providing good interface conditions for subsequent electroplating and painting processes.

[0014] Preferably, the proportion of glass fibers with a retention length distribution in the range of 10-99 μm in the nylon composition is 90-100%, and the proportion of glass fibers with a retention length distribution in the range of 100-300 μm is 0-10%.

[0015] Preferably, the relative viscosity of the first PA resin is 3-5.0.

[0016] Preferably, the relative viscosity of the nylon composition is 2.6-3.1.

[0017] Preferably, the glass fiber can be alkali-free E-class glass fiber, including but not limited to ordinary glass fiber, hydrolysis-resistant glass fiber, and flat glass fiber.

[0018] Preferably, the diameter of the glass fiber is 7-12 μm.

[0019] It should be noted that the heat treatment of the nylon composition only shortens the retained length of the glass fiber, without affecting the retained diameter of the glass fiber. This is because glass fiber has a high modulus and hardness. In the shear field of twin-screw extrusion, the shear force between the resin matrix and the glass fiber mainly causes the glass fiber to break and its length to decrease. However, this shear force is insufficient to produce radial extrusion, grinding or etching effects on the glass fiber monofilaments. Therefore, the diameter of the glass fiber remains basically unchanged.

[0020] Preferably, the retained diameter of the glass fiber is 7-12 μm.

[0021] Preferably, the glass fiber has a length of 3-5 mm and an aspect ratio of 1:(3-4).

[0022] Preferably, the first PA resin and the second PA resin are selected from at least one of PA6, PA66, and PA56.

[0023] Preferably, the nylon composition may be selected from PCR-recycled nylon resin.

[0024] In the polyamide composite material, the amount of the first PA resin is 48-72 parts, for example, it can be 48 parts, 50 parts, 52 parts, 54 parts, 56 parts, 58 parts, 60 parts, 62 parts, 64 parts, 66 parts, 68 parts, 70 parts, 72 parts or any two of these values.

[0025] Preferably, the amount of the first PA resin is 50-70 parts.

[0026] The weight percentage of the first PA resin in the polyamide composite material of the present invention is not less than 60%.

[0027] Preferably, the weight percentage of the first PA resin in the polyamide composite material is 65-88%.

[0028] More preferably, the weight percentage of the first PA resin in the polyamide composite material is 70-80%.

[0029] In the polyamide composite material, the amount of the nylon composition is 9-26 parts, for example, it can be 9 parts, 10 parts, 12 parts, 14 parts, 16 parts, 18 parts, 20 parts, 21 parts, 22 parts, 24 parts, 26 parts or any two of these values.

[0030] Preferably, the amount of the nylon composition is 10-25 parts.

[0031] The nylon composition of the present invention has a weight percentage of not less than 10% in the polyamide composite material.

[0032] Preferably, the nylon composition has a weight percentage of 15-35% in the polyamide composite material.

[0033] More preferably, the nylon composition has a weight percentage of 20-30% in the polyamide composite material.

[0034] Preferably, the nylon composition comprises the following components in parts by weight: 49-96 parts of second PA resin; 4-51 parts of glass fiber.

[0035] In the nylon composition, the amount of the second PA resin is 49-96 parts, for example, it can be 49 parts, 50 parts, 55 parts, 60 parts, 65 parts, 70 parts, 75 parts, 80 parts, 85 parts, 90 parts, 95 parts, 96 parts, or any two of these values.

[0036] Preferably, the amount of the second PA resin is 50-95 parts.

[0037] The second PA resin in the nylon composition of the present invention has a weight percentage of not less than 40%.

[0038] Preferably, the second PA resin has a weight percentage of 50-80% in the nylon composition.

[0039] In the nylon composition, the amount of glass fiber is 4-51 parts, for example, it can be 4 parts, 5 parts, 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, 45 parts, 50 parts, 51 parts or any two of these values.

[0040] Preferably, the amount of glass fiber used is 5-50 parts.

[0041] The glass fiber content in the nylon composition of the present invention is not less than 5% by weight.

[0042] Preferably, the glass fiber has a weight percentage of 10-40% in the nylon composition.

[0043] Preferably, the additives include 0.2-0.5 parts of antioxidant and 0.3-1 parts of lubricant.

[0044] Preferably, the nylon composition further includes 0.2-0.5 parts of an antioxidant.

[0045] Preferably, the antioxidant includes at least one of hindered phenolic antioxidants, phosphite antioxidants, and thioester antioxidants.

[0046] More preferably, the hindered phenolic antioxidant includes at least one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (antioxidant 1010), octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (antioxidant 1076), tris(3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate (antioxidant 3114), antioxidant 168, and antioxidant PEP-36.

[0047] More preferably, the phosphite antioxidant includes at least one of tris(2,4-di-tert-butylphenyl) phosphite (antioxidant 168) and pentaerythritol dibis(2,4-tert-butylphenyl) phosphite (antioxidant 626).

[0048] Preferably, the lubricant includes at least one of rice bran wax salt and silicone.

[0049] Secondly, the present invention also discloses a method for preparing a polyamide composite material, comprising the following steps: After the components are mixed evenly, they are added to a twin-screw extruder for melt mixing, extrusion granulation, and polyamide composite material is obtained.

[0050] Preferably, the temperature of the melt mixing is 220-260℃, and the screw speed is 300-800 r / min.

[0051] Preferably, the method for preparing the nylon composition includes the following steps: The components of the nylon composition are blended, then extruded and granulated after melt processing and injection molded into color plates; the color plates are placed in a xenon lamp aging chamber for irradiation for 900-1000 hours, then removed, crushed, and the nylon composition is obtained.

[0052] It should be noted that this invention utilizes accelerated photothermal aging to simulate the wear and tear of reinforced nylon materials during use. This invention employs the SAE J2527 method, placing color samples in a xenon lamp aging chamber for accelerated photothermal aging. The irradiation intensity tested in SAE J2527 is 0.5-0.6 W / m². 2 ·nm -1 (Under 340nm conditions).

[0053] Preferably, the melting process temperature is 270-290℃ and the screw speed is 300-1000 rpm.

[0054] Thirdly, the present invention also discloses the application of a polyamide composite material in the preparation of automotive parts. In particular, the polyamide composite material can be used to prepare functional parts that require surface treatment (electroplation, painting) or have special appearance requirements, such as plastic inserts for electronic devices (main frame, bracket), interior and exterior structural parts for automobiles (rearview mirror bracket, interior cup holder bracket, etc.), and functional components for precision instruments.

[0055] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention, by incorporating a nylon composition into a first PA resin, enables the polyamide composite material to exhibit excellent surface electroplating and painting properties. The core of this invention lies in utilizing the unique distribution of glass fiber retention within the nylon composition (shorter retention length, allowing for better dispersion of glass fibers on the material surface and resulting in superior surface treatment). Furthermore, since the molecular weight of the nylon composition decreases further after reprocessing, the addition of the first PA resin to the nylon composition effectively compensates for the overall performance degradation caused by this molecular weight reduction. Simultaneously, by controlling the relative viscosity of the first PA resin and the nylon composition, this invention further enhances the surface treatment and mechanical properties of the polyamide composite material. Detailed Implementation

[0056] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0057] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0058] In this application, numerical ranges are referred to as continuous unless otherwise specified, and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0059] Examples 1-13 Examples of the polyamide composite material and its preparation method according to the present invention are shown in Table 1.

[0060] The preparation method of the polyamide composite material includes the following steps: mixing each component evenly and then adding it to a twin-screw extruder for melt mixing, extrusion granulation, and obtaining the polyamide composite material. The melt mixing temperature is 220℃, and the screw speed is 600 rpm.

[0061] Comparative Examples 1-8 The only differences between the comparative examples and the embodiments are the types and proportions of components, as shown in Table 2. Specifically, the difference between Comparative Example 8 and Comparative Example 6 is that the screw speed in Comparative Example 6 was 600 rpm during the preparation of the polyamide composite material, while the screw speed in Comparative Example 8 was 750 rpm.

[0062] In the components described in each embodiment and comparative example: PA resin 1 is PA6: relative viscosity 2.8, BE3280, purchased from Hongsheng; PA resin 2 is PA66: relative viscosity is 2.7, PA66 EPR27, purchased from Shenma in Pingdingshan, Henan. PA resin 3 is PA66: relative viscosity 3.1, T31, purchased from Huafeng; PA resin 4 is PA66: relative viscosity is 3.7, PA66 T37, purchased from Huafeng; PA resin 5 is PA66: relative viscosity is 2.4, PA66 EPR24, purchased from Shenma in Pingdingshan, Henan.

[0063] Nylon composition 1 comprises 50 parts of PA resin 3, 50 parts of glass fiber, and 0.2 parts of antioxidant. By controlling the screw speed to 500-600 rpm, 80% of the glass fiber retains a length distribution of 10-199 μm, and 20% of the glass fiber retains a length distribution of 200-300 μm. The relative viscosity of nylon composition 1 is 2.9.

[0064] Nylon composition 2 comprises 75 parts of PA resin 3, 25 parts of glass fiber, and 0.3 parts of antioxidant. By controlling the screw speed to 500-600 rpm, 80% of the glass fiber retains a length distribution of 10-199 μm, and 20% of the glass fiber retains a length distribution of 200-300 μm. The relative viscosity of nylon composition 2 is 3.0.

[0065] Nylon composition 3 comprises 95 parts of PA resin 3, 5 parts of glass fiber, and 0.5 parts of antioxidant; by controlling the screw speed to 500-600 rpm, 80% of the glass fiber retains a length distribution of 10-199 μm, and 20% of the glass fiber retains a length distribution of 200-300 μm. The relative viscosity of nylon composition 3 is 3.0.

[0066] Nylon composition 4 comprises 75 parts of PA resin 2, 25 parts of glass fiber, and 0.3 parts of antioxidant. By controlling the screw speed to 500-600 rpm, 80% of the glass fiber retains a length distribution of 10-199 μm, and 20% of the glass fiber retains a length distribution of 200-300 μm. The relative viscosity of nylon composition 4 is 2.6.

[0067] Nylon composition 5 comprises 75 parts of PA resin 4, 25 parts of glass fiber, and 0.3 parts of antioxidant. By controlling the screw speed to 500-600 rpm, 80% of the glass fiber retains a length distribution of 10-199 μm, and 20% of the glass fiber retains a length distribution of 200-300 μm. The relative viscosity of nylon composition 5 is 3.6.

[0068] Nylon composition 6 comprises 75 parts of PA resin-3, 25 parts of glass fiber, and 0.3 parts of antioxidant. By controlling the screw speed to 800-900 rpm, 90% of the glass fiber retains a length distribution ranging from 10 to 99 μm, and 10% of the glass fiber retains a length distribution ranging from 100 to 300 μm. The relative viscosity of nylon composition 6 is 2.8.

[0069] Nylon composition 7 comprises 75 parts of PA resin-3, 25 parts of glass fiber, and 0.3 parts of antioxidant. By controlling the screw speed to 200-300 rpm, 80% of the glass fiber retains a length distribution above 500 μm, and 20% retains a length distribution below 500 μm. The relative viscosity of nylon composition 7 is 2.95.

[0070] Nylon composition 8 comprises 75 parts of PA resin 5, 25 parts of glass fiber, and 0.3 parts of antioxidant. By controlling the screw speed to 500-600 rpm, 80% of the glass fiber retains a length distribution of 10-199 μm, and 20% retains a length distribution of 200-300 μm. The relative viscosity of nylon composition 8 is 2.2.

[0071] Nylon composition 9 comprises 75 parts of PA resin 3, 25 parts of glass fiber, and 0.3 parts of antioxidant; by controlling the screw speed to 950-1000 rpm, the retention length distribution of 100% glass fiber is made to be 10-100 μm. The relative viscosity of nylon composition 9 is 2.7.

[0072] Nylon composition 10 comprises 75 parts PA resin, 3 parts glass fiber, and 0.5 parts antioxidant. By controlling the screw speed to 350-450 rpm, 90% of the glass fiber retention length is distributed below 500 μm, and 10% of the glass fiber retention length is distributed above 500 μm. The relative viscosity of nylon composition 10 is 3.0.

[0073] The glass fiber is flat glass fiber: TFG-3.0-T436, purchased from Taishan, with a chopped length of 3.0-4.5mm and a flatness ratio of 1:3.5-1:4.

[0074] Antioxidant: RIANOX 1098, purchased from Rianon.

[0075] Lubricant: MB50-002, purchased from Dow Corning.

[0076] The preparation method of the nylon composition includes the following steps: blending the components in proportion, then adding them to a screw extruder and melting them at 280°C, followed by extrusion granulation and injection molding into color plates; placing the color plates in a xenon lamp aging chamber and irradiating them for 1000 hours according to SAE J2527 method, then removing them and mechanically crushing them into fragments with a particle size of less than 1 cm to obtain the nylon composition. The above nylon compositions 1-10 are simulated recovered PCR raw materials.

[0077] The testing conditions for SAE J2527 are as follows: irradiance of 0.55 W / m². 2 ·nm -1(At 340nm) the filter combination is extended ultraviolet (Q / S). The photoaging cycle is divided into two parts: a light phase and a dark phase, with a total irradiation time of 2000h.

[0078] Unless otherwise specified, all components and raw materials used in the embodiments and comparative examples of this invention are commercially available, and the same type of components and raw materials are used in each parallel experiment.

[0079] Table 1 Table 2 To verify the performance of the polyamide composite material described in this invention, the polyamide composite materials prepared in each embodiment and comparative example were injection molded into specimens for testing the following properties.

[0080] Performance testing methods: 1. Mechanical property testing: According to ISO527-1 / 2 standard, test specimens with a thickness of 4mm were made using an injection molding machine. The tensile strength of the specimens was tested under the conditions of 23℃ and a test speed of 5mm / min. The notched impact strength of the dry specimens at 23℃ was tested according to ISO179 / 1eA.

[0081] 2. Surface treatment performance test: Use an injection molding machine to make a standard color swatch with a thickness of 2mm, and test the uniformity of paint spraying and electroplating.

[0082] (1) The process of judging the uniformity of paint spraying: 1) Apply the prepared paint evenly to the surface of the standard color swatch using a spraying method. Then, dry the standard color swatch to ensure the coating is fully dry and forms a dense, firmly adhered paint film, thus completing the painting process. The paint thickness is 10μm.

[0083] 2) Use a scanning electron microscope (SEM) to observe the surface of the painted sample and count the proportion of the area of ​​defects such as bubbles, bumps, and pits to the total observed area. Record this as the proportion of painted defect area. If the proportion is ≤3%, the painting is considered smooth.

[0084] (2) The process of judging the uniformity of electroplating: 1) A conductive metal layer is deposited on the surface of a standard color plate using chemical plating. The color plate is then immersed in the corresponding electroplating solution as a cathode, with the corresponding metal as the anode. Under the influence of an electric field, metal ions in the plating solution are reduced on the cathode surface and continuously deposited to form a metal coating. After electroplating, the color plate undergoes multiple stages of washing, passivation, or sealing treatment, and is then dried to obtain a plastic color plate with a metal coating. The coating thickness is 10 μm.

[0085] 2) Use a scanning electron microscope (SEM) to observe the surface of the electroplated sample and count the proportion of the area of ​​defects such as bubbles, protrusions, and pits to the total observed area. Record this as the electroplating defect area ratio. If the ratio is ≤3%, the electroplating is considered smooth.

[0086] The performance parameters obtained from the above tests are shown in Table 3.

[0087] Table 3 As can be seen from Examples 1-13, the tensile strength of the polyamide composite material of the present invention is above 85 MPa, and the defect area ratio of painting and electroplating is below 3%, indicating that the polyamide composite material of the present invention has excellent mechanical properties and surface treatment properties.

[0088] Comparing Comparative Examples 1 and 7 with Example 3, it can be seen that if the relative viscosity of the PA resin or nylon composition in the polyamide composite material is lower than 2.7, the mechanical properties and surface treatment properties of the composite material will decrease. Therefore, by controlling the viscosity of the PA resin in the polyamide composite material and the viscosity of the nylon composition within the range defined by this invention, the mechanical properties of the composite material will not be significantly reduced after processing, and it will have excellent surface treatment properties.

[0089] A comparison of Comparative Examples 2-5 with Example 3 shows that if the amount of PA resin or nylon composition in the polyamide composite material is too low or too high, it will affect the mechanical properties and surface treatment properties of the composite material. Therefore, by controlling the amount of PA resin and nylon composition in the polyamide composite material within the range defined by this invention, the polyamide composite material can simultaneously possess excellent mechanical properties and surface treatment properties.

[0090] Comparing Comparative Example 6 with Example 3, it can be seen that if the retention length distribution range of glass fibers is greater than 500 μm, the surface treatment performance of the composite material will be affected. This shows that by controlling the retention length distribution range of glass fibers to be no greater than 500 μm, the present invention can enable polyamide composite materials to have both excellent mechanical properties and surface treatment performance.

[0091] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A polyamide composite material, characterized in that, The components include the following parts by weight: First, 48-72 parts of PA resin; 9-26 parts of nylon composition; 0.5-3 parts of additives; The nylon composition comprises a second PA resin and glass fibers, wherein the proportion of glass fibers with a retention length distribution below 500 μm in the nylon composition is 90-100%, and the proportion of glass fibers with a retention length distribution above 500 μm is 0-10%. The relative viscosity of the first PA resin is not less than 2.7, and the relative viscosity of the nylon composition is not less than 2.

4.

2. The polyamide composite material as described in claim 1, characterized in that, The relative viscosity of the first PA resin is 3-5.

0.

3. The polyamide composite material as described in claim 1, characterized in that, The proportion of glass fibers with a retention length distribution in the range of 10-299 μm in the nylon composition is 90-100%, and the proportion of glass fibers with a retention length distribution in the range of 300-500 μm is 0-10%. Alternatively, the proportion of glass fibers in the nylon composition with a retention length distribution in the range of 10-199 μm is 80-100%, and the proportion of glass fibers with a retention length distribution in the range of 200-300 μm is 0-20%.

4. The polyamide composite material as described in claim 1, characterized in that, The proportion of glass fibers with a retention length in the nylon composition is 90-100% in the range of 10-99 μm, and the proportion of glass fibers with a retention length in the range of 100-300 μm is 0-10%.

5. The polyamide composite material as described in claim 1, characterized in that, The nylon composition comprises the following components in parts by weight: 49-96 parts of second PA resin; 4-51 parts of glass fiber.

6. The polyamide composite material according to claim 1, characterized in that, The first PA resin and the second PA resin are selected from at least one of PA6, PA66, and PA56, respectively.

7. The polyamide composite material according to claim 1, characterized in that, The relative viscosity of the nylon composition is 2.6-3.

1.

8. A method for preparing a polyamide composite material according to any one of claims 1-7, characterized in that, Includes the following steps: After the components are mixed evenly, they are added to a twin-screw extruder for melt mixing, extrusion granulation, and polyamide composite material is obtained.

9. The use of a polyamide composite material according to any one of claims 1-7 in the manufacture of automotive parts.

10. An automotive component, characterized in that, It is prepared using the polyamide composite material described in any one of claims 1-7.

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