Preparation method of polypropylene composite material, polypropylene composite material and mudguard

Abstract

The invention provides a preparation method of a polypropylene composite material, the polypropylene composite material and a fender, the preparation method of the polypropylene composite material comprises the following steps: at least adding an ultraviolet light absorber, an antioxidant, an elastomer and a light screening agent into polypropylene, mixing and drying to obtain an intermediate; and extruding and granulating the intermediate by using a double-screw extruder to obtain the polypropylene composite material. The problem that in the prior art, a polypropylene material is poor in weather resistance in high-temperature and strong-ultraviolet-ray areas is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of preparation of polypropylene materials, and in particular to a preparation method of a polypropylene composite material, a polypropylene composite material and a fender. Background Art

[0002] Commercial fenders are key components that protect commercial vehicle bodies from the impact of debris such as mud, sand, and gravel during driving. They can effectively reduce damage to the vehicle body and the repair costs of chassis components, especially under complex road conditions. Traditional technologies, such as using fenders modified from waste rubber powder, can reduce raw material costs, but their mechanical properties and lifespan are poor; and fenders made of polyethylene materials improve the material's resistance to environmental stress, but are prone to aging under long-term ultraviolet rays and high temperatures, making them unsuitable for use in high-temperature areas. In contrast, polypropylene fenders have a wider range of applications and better weather resistance, making them an ideal choice for commercial vehicles in high-temperature environments. However, polypropylene fenders have poor weather resistance in high-temperature and ultraviolet environments, are easily photo-oxidized and thermally oxidized, and are prone to aging when exposed to ultraviolet rays for a long time. How to improve the weather resistance of fenders when used in high-temperature areas while ensuring that their mechanical properties are not reduced is a key issue that needs to be urgently addressed in this field.

[0003] Currently, no effective solutions have been proposed for the problems in the existing technology. Summary of the Invention

[0004] The main purpose of the present invention is to provide a preparation method of a polypropylene composite material, a polypropylene composite material and a fender, so as to solve the problem that the polypropylene material in the prior art has poor weather resistance in high temperature and strong ultraviolet areas.

[0005] To achieve the above-mentioned object, according to one aspect of the present invention, a method for preparing a polypropylene composite material is provided, comprising: adding at least an ultraviolet absorber, an antioxidant, an elastomer, and a light shielding agent to polypropylene, mixing and drying to obtain an intermediate; and extruding and granulating the intermediate using a twin-screw extruder to obtain a polypropylene composite material.

[0006] Furthermore, at least an ultraviolet absorber, an antioxidant, an elastomer, and a light shielding agent are added to the polypropylene, which includes: adding an ultraviolet absorber, an antioxidant, an elastomer, a light shielding agent, talcum powder, and a lubricant to the polypropylene.

[0007] Furthermore, at least an ultraviolet absorber, an antioxidant, an elastomer, and a light shielding agent are added to the polypropylene, including: adding a hindered amine light stabilizer, an ultraviolet absorber, an antioxidant, an elastomer, a light shielding agent, talcum powder, and a lubricant to the polypropylene.

[0008] Furthermore, the molecular weight of the hindered amine light stabilizer is A, 4000 g / mol≥A≥1000 g / mol.

[0009] Furthermore, in the step of adding an ultraviolet absorber, an antioxidant, an elastomer, a light shielding agent, talc, and a lubricant to polypropylene, based on 100 parts of the total mass, the amount of the elastomer added is 5-15 parts, the amount of the ultraviolet absorber added is 0.8-1.5 parts, the amount of the antioxidant added is 0.2-0.5 parts, the amount of the light shielding agent added is 1-3 parts, the amount of talc added is 15-30 parts, and the amount of the lubricant added is 0.5-1 part.

[0010] Further, the elastomer includes EPDM.

[0011] Furthermore, the ultraviolet absorber includes UV-531.

[0012] Further, the light-shielding agent includes carbon black.

[0013] According to one aspect of the present invention, a polypropylene composite material is provided. The polypropylene composite material is prepared using the above-mentioned method for preparing the polypropylene composite material.

[0014] According to another aspect of the present invention, a fender is provided. The fender is made by injection molding a polypropylene composite material, and the polypropylene composite material is the polypropylene composite material mentioned above.

[0015] By applying the technical solution of the present invention, the addition of ultraviolet absorbers can effectively absorb and convert ultraviolet energy, avoid the photooxidation reaction of polypropylene molecular chains, and significantly extend the service life of the material in harsh outdoor environments; the light shielding agent reduces direct ultraviolet radiation through physical shielding, further enhancing the weather resistance of the composite material; the antioxidant can inhibit or delay the oxidative degradation of polypropylene caused by oxygen during processing and use, maintaining the color and mechanical properties of the material. In high-temperature environments, the effect of the antioxidant is significant, and can effectively prevent the material from discoloring and performance degradation. At the same time, the addition of the elastomer enhances the toughness and impact resistance of the composite material, allowing the material to maintain good elasticity even under low temperature conditions and avoid brittle cracking. The synergistic effect of the above additives not only improves the aging resistance and mechanical properties of polypropylene, but also ensures the stability of the material under different environmental conditions, making it an ideal fender material for commercial vehicles in high-temperature areas. This application effectively solves the problem of poor weather resistance of polypropylene materials in high-temperature and strong ultraviolet areas. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0017] Figure 1The figure shows a flow chart of an embodiment of a method for preparing a polypropylene composite material according to the present invention. DETAILED DESCRIPTION

[0018] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0019] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0020] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way are interchangeable where appropriate, so that the embodiments of the present application described herein can, for example, be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0021] Now, exemplary embodiments according to the present application will be described in more detail with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in a variety of different forms and should not be interpreted as being limited to the embodiments described herein. It should be understood that these embodiments are provided to make the disclosure of this application thorough and complete, and to fully convey the concepts of these exemplary embodiments to those of ordinary skill in the art. In the accompanying drawings, for the sake of clarity, the thickness of layers and regions may be exaggerated, and the same reference numerals are used to represent the same devices, and thus their descriptions will be omitted.

[0022] Commercial vehicles often operate in complex road conditions, and mud, gravel, and other debris kicked up by the wheels can cause wear and scratches on the vehicle's paint. Mudguards prevent this debris from directly impacting the vehicle's body, thereby protecting the integrity and aesthetics of the paint and extending the vehicle's service life. Furthermore, debris kicked up by the wheels during operation can enter the vehicle's chassis, damaging various components such as the brake system and transmission. Mudguards prevent this debris from entering the chassis, reducing the risk of damage to chassis components and lowering vehicle repair costs.

[0023] Prior art discloses a waste rubber powder vehicle fender and its preparation method. The waste rubber powder vehicle fender comprises three layers: an inner layer, a middle layer, and an outer layer. Undesulfurized waste rubber powder is blended with polyolefin, chlorinated polyethylene, a compatibilizer, flow modifier 1, and flow modifier 2, extruded, granulated, and dried. The resulting particles are then melted and embedded in a reinforcing layer until the molten resin is formed, forming the vehicle fender's middle layer. The outer and inner layers are then bonded to the middle layer using hot pressing to form the waste rubber powder vehicle fender. While using waste rubber reduces raw material costs, it also reduces mechanical properties and lifespan.

[0024] Prior art discloses a high-impact rotomolded automotive fender. This utilizes linear low-density polyethylene (LLDPE), high-density polyethylene (HDPE), and EVA to enhance strength, address the material's poor environmental stress resistance, meet rolling resistance processing requirements, and extend the fender's lifespan. However, while polyethylene fenders maintain a certain degree of toughness at low temperatures and resist brittle cracking, they are susceptible to photo- and thermal-oxidation and deteriorate under prolonged UV exposure. Polypropylene fenders offer a wider range of applications for commercial vehicles.

[0025] Therefore, there is an urgent need for a material that can maintain mechanical and mechanical properties while having high weather resistance.

[0026] Combine Figure 1 As shown, according to a specific embodiment of the present application, a method for preparing a polypropylene composite material is provided.

[0027] The preparation method of the polypropylene composite material comprises:

[0028] Step S1: adding at least an ultraviolet absorber, an antioxidant, an elastomer, and a light shielding agent to polypropylene, mixing, and drying to obtain an intermediate;

[0029] Step S2: using a twin-screw extruder to extrude and granulate the intermediate to obtain a polypropylene composite material.

[0030] By applying the technical solution of the present invention, the addition of ultraviolet absorbers can effectively absorb and convert ultraviolet energy, avoid the photooxidation reaction of polypropylene molecular chains, and significantly extend the service life of the material in harsh outdoor environments; the light shielding agent reduces direct ultraviolet radiation through physical shielding, further enhancing the weather resistance of the composite material; the antioxidant can inhibit or delay the oxidative degradation of polypropylene caused by oxygen during processing and use, maintaining the color and mechanical properties of the material. In high-temperature environments, the effect of the antioxidant is significant, and can effectively prevent the material from discoloring and performance degradation. At the same time, the addition of the elastomer enhances the toughness and impact resistance of the composite material, allowing the material to maintain good elasticity even under low temperature conditions and avoid brittle cracking. The synergistic effect of the above additives not only improves the aging resistance and mechanical properties of polypropylene, but also ensures the stability of the material under different environmental conditions, making it an ideal fender material for commercial vehicles in high-temperature areas. This application effectively solves the problem of poor weather resistance of polypropylene materials in high-temperature and strong ultraviolet areas.

[0031] By adopting the technical solution of the present application, the high-weather-resistant polypropylene fender can withstand xenon lamp aging for more than 1250 hours according to the test method of GB / T 16422.2-2022 (cycle number 4-narrow band), and the equivalent actual vehicle will not show obvious discoloration within one year of use in high-temperature areas.

[0032] The addition of elastomers (such as EPDM) enhances the toughness and impact resistance of the composite material, which is a very important performance indicator for fenders that need to withstand the impact of splashes during high-speed movement.

[0033] Extrusion granulation through a twin-screw extruder not only improves material dispersion uniformity but also promotes interaction between components, resulting in better processing fluidity for the composite material. This ensures smooth subsequent injection molding, improving production efficiency and product quality. This preparation method significantly enhances the polypropylene composite's weather resistance in high-temperature, ultraviolet (UV) environments while maintaining excellent mechanical properties, making it ideal for commercial vehicle fenders subject to prolonged use in extreme weather conditions.

[0034] Elastomers (such as POE and EPDM) improve the brittleness of polyethylene, enhancing its impact resistance and low-temperature toughness. These are key to the fender's bending and collision resistance. Without elastomers, the material is prone to breakage, especially at low temperatures or under dynamic loads.

[0035] Carbon black provides reinforcement (increasing tensile strength and abrasion resistance), UV protection (fenders are exposed outdoors for extended periods and require protection against aging), and coloring (black is a common fender color). While carbon black can be partially replaced with other fillers or pigments for coloring, overall performance (especially weather resistance) will be significantly reduced.

[0036] The role of lubricants (such as zinc stearate, paraffin wax, etc.) is to improve processing fluidity, reduce mold sticking, and improve surface finish. For fenders with complex shapes, lubricants can avoid processing defects, but if the processing technology is simple (such as flat plate extrusion), the amount may be reduced as appropriate.

[0037] The effects of talc include: reducing costs, increasing rigidity (but potentially reducing toughness), and improving dimensional stability. In an optional embodiment, talc can be replaced with other mineral fillers (such as calcium carbonate), or omitted entirely to prioritize toughness. If lightweight or high toughness is desired, the amount of talc can be reduced and the proportion of elastomer increased;

[0038] Common types of UV absorbers (UVA) include the following three categories:

[0039] 1. Benzotriazoles (such as Tinuvin 328, UV-327), features: efficient absorption of 280-380nm ultraviolet rays, high temperature resistance, suitable for polyolefins and engineering plastics.

[0040] 2. Benzophenones (such as UV-531, Chimassorb 81). Features: absorbs 250-350nm ultraviolet rays, low cost.

[0041] 3. Triazines (such as Tinuvin 1577). Features: Broad spectrum absorption (280-400nm), high temperature resistance, suitable for automotive coatings and high-end plastics.

[0042] UV absorbers absorb UV energy through the conjugated system (such as benzene ring, heterocyclic ring) in their molecular structure and convert it into harmless heat energy (molecular vibration / rotation) without undergoing chemical changes themselves (reversible process). The reaction formula is:

[0043] The reaction formula of ultraviolet absorber: UVA+UV photon→UVA*→UVA+heat UVA+UV photon→UVA*→UVA+heat.

[0044] Furthermore, at least an ultraviolet absorber, an antioxidant, an elastomer, and a light shielding agent are added to the polypropylene, which includes: adding an ultraviolet absorber, an antioxidant, an elastomer, a light shielding agent, talcum powder, and a lubricant to the polypropylene.

[0045] Optional light shielding agents include carbon black (the best effect is achieved when the particle size is 20 to 50 nm), titanium dioxide (TiO2) (rutile type, surface coating treatment), and zinc oxide (ZnO). Light shielding agents reduce UV penetration into the material by reflecting or scattering ultraviolet rays (physical shielding).

[0046] Carbon black: Full-band shielding, but only suitable for black products.

[0047] TiO2 / ZnO: Particle size and dispersibility need to be optimized to avoid catalytic photooxidation (surface modification is required).

[0048] Furthermore, at least an ultraviolet absorber, an antioxidant, an elastomer, and a light shielding agent are added to the polypropylene, including: adding a hindered amine light stabilizer, an ultraviolet absorber, an antioxidant, an elastomer, a light shielding agent, talcum powder, and a lubricant to the polypropylene.

[0049] There are two common types of hindered amine light stabilizers (HALS): low molecular weight HALS (such as Tinuvin 770), which are suitable for thin products (such as films and fibers); and high molecular weight HALS (such as Chimassorb 944), which are resistant to migration and suitable for thick products (such as automotive parts). High molecular weight HALS (Hindered Amine Light Stabilizers, HALS) refers to hindered amine light stabilizers with a molecular weight generally above 1000 g / mol. Compared with low molecular weight HALS (such as Tinuvin 770, MW = 481), they have lower migration and longer durability, and are suitable for thick-walled products and polymer materials used outdoors for a long time (such as automotive parts).

[0050] Hindered amine light stabilizers capture free radicals by generating nitroxide free radicals (NO·) and interrupting the photooxidation chain reaction. Their advantage is long-term stability, making them particularly suitable for materials exposed outdoors for a long time (such as fenders).

[0051] Furthermore, the molecular weight of the hindered amine light stabilizer is A, 4000 g / mol ≥ A ≥ 1000 g / mol. High molecular weight HALS are more resistant to migration in non-polar matrices (such as PE).

[0052] For example, Chimassorb 944 (BASF) is a high-molecular-weight HALS material with a molecular weight of 2000-3000 g / mol and a chemical name / structure of poly{[6-(1,1,3,3-tetramethylbutyl)amino-1,3,5-triazine-2,4-diyl][(2,2,6,6-tetramethyl-4-piperidinyl)imino]-1,6-hexanediyl[(2,2,6,6-tetramethyl-4-piperidinyl)imino]}. It is suitable for polymers such as PE, PP, TPO, and engineering plastics.

[0053] Hindered amine light stabilizers with a molecular weight within the above range, due to their moderate molecular size, can be better dispersed in the polypropylene matrix, reducing chemical aggregation and thus improving compatibility with the matrix material. This facilitates uniform distribution within the composite material, ensuring comprehensive and long-lasting light stabilization. The high molecular weight makes it difficult to precipitate from the polymer matrix, preventing surface blooming or volatilization losses, and provides better long-term stability, making it suitable for high-temperature processing (such as injection molding and extrusion) and long-term outdoor exposure environments. Low molecular weight HALS may be inactivated by carbon black adsorption, while high molecular weight HALS are less affected and are suitable for systems containing carbon black (such as black fenders).

[0054] Light stabilizers with lower molecular weights may volatilize or migrate during processing, resulting in reduced effectiveness. Light stabilizers with excessively high molecular weights may affect the material's transparency and surface quality due to uneven dispersion. Selecting this molecular weight range prevents volatilization and migration while maintaining the composite's excellent appearance and physical properties, such as impact resistance and toughness. Furthermore, hindered amine light stabilizers with moderate molecular weights can more fully react with free radicals in the polypropylene molecular chain, inhibiting the occurrence of photooxidative chain reactions, thereby enhancing the composite's resistance to photooxidation and preventing discoloration, powdering, and performance degradation.

[0055] Furthermore, in the step of adding an ultraviolet absorber, an antioxidant, an elastomer, a light shielding agent, talc, and a lubricant to polypropylene, based on 100 parts of the total mass, the amount of the elastomer added is 5-15 parts, the amount of the ultraviolet absorber added is 0.8-1.5 parts, the amount of the antioxidant added is 0.2-0.5 parts, the amount of the light shielding agent added is 1-3 parts, the amount of talc added is 15-30 parts, and the amount of the lubricant added is 0.5-1 part.

[0056] Further, the elastomer includes EPDM.

[0057] Furthermore, the ultraviolet absorber includes UV-531.

[0058] UV-531 belongs to the benzophenone class of ultraviolet absorbers (UVA) and is a benzophenone derivative. Chemical name: 2-hydroxy-4-n-octyloxybenzophenone; CAS number: 1843-05-6;

[0059] UV-531 absorption band: 280~350nm (covering UV-B and part of UV-A).

[0060] The mechanism of action of UV-531 is: it absorbs ultraviolet energy through the o-hydroxybenzophenone structure in the molecule and converts it into harmless heat energy (breakage and recombination of intramolecular hydrogen bonds): UV-531+UV photon→excited state UV-531*→heat energy release+ground state UV-531UV-531+UV photon→excited state UV-531*→heat energy release+ground state UV-531.

[0061] UV-531 offers low cost and wide compatibility (suitable for PE, PP, PVC, coatings, etc.). The difference between UV-531 and HALS is that UV-531 directly absorbs UV rays, providing physical protection, while HALS captures free radicals through chemical recycling, providing chemical protection. The technical solution of this application achieves dual protection.

[0062] In an optional embodiment, the antioxidant (1010 / 168 combination) generally refers to a combination system consisting of two different antioxidants: Irganox 1010 (chemical name: pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate) and Irgafos 168 (chemical name: tris(2,4-di-tert-butylphenyl) phosphite). These two antioxidants are often used in combination due to their synergistic effect, which can more effectively prevent the performance degradation of polymer materials caused by oxidation during processing and use.

[0063] Irganox 1010 is a primary antioxidant from the phenolic antioxidant family. It protects polymers from oxidative damage by capturing free radicals generated during polymer oxidation, interrupting the oxidation chain reaction. Due to its high efficacy and broad applicability, this antioxidant is widely used in polyolefins (such as polypropylene) and various other plastic materials.

[0064] Irgafos 168 is a secondary antioxidant, also known as a phosphite antioxidant. Its primary function is to decompose the hydroperoxides formed during the initial stages of polymer oxidation, preventing them from further decomposing and producing new free radicals. It also protects Irganox 1010 from oxidation, extending its effectiveness in the material.

[0065] When Irganox 1010 and Irgafos 168 are combined in appropriate proportions, they form a highly effective antioxidant network. Irganox 1010 first captures free radicals, while Irgafos 168 decomposes hydroperoxides and protects Irganox 1010 from being consumed. This synergistic effect ensures that the composite maintains excellent aging resistance under both processing conditions (such as high temperatures) and operational environments (such as sunlight and high temperatures), while also preserving the material's color and mechanical properties.

[0066] In the preparation of polypropylene composite materials, the addition of the 1010 / 168 compound system can not only effectively inhibit the thermal oxidative degradation of polypropylene during processing, but also improve the material's ability to resist environmental stress in actual use. This high-performance antioxidant compound system is especially indispensable for commercial vehicle fenders that need to serve under high temperatures and direct sunlight.

[0067] In a specific embodiment, the present invention provides a highly weather-resistant polypropylene fender for commercial vehicles in high-temperature areas. The base material is polypropylene, which is modified by adding an elastomer. The remaining additives include talcum powder, antioxidants, ultraviolet absorbers, lubricants and carbon black.

[0068] The elastomer added to the high-weather-resistant polypropylene fender is EPDM, with an addition amount of 5-15%, which can increase the toughness of the product and improve low-temperature impact resistance;

[0069] The ultraviolet absorber added to the high weather-resistant polypropylene fender is UV-531, and the added amount is 0.8% to 1.5%.

[0070] The talc powder added to the high-weather-resistant polypropylene fender is 15-30% to enhance rigidity and dimensional stability; the antioxidant (1010 / 168 compound) added is 0.2-0.5% to prevent oxidative degradation during processing and use; the lubricant (calcium stearate) added is 0.5-1% to improve processing fluidity; the carbon black added is 1-3% for coloring and partial UV protection.

[0071] The preparation process of the present invention comprises raw material drying, mixing and granulation, and injection molding. The injection molding process includes four steps: melt plasticization, injection mold filling, cooling and shaping, and demolding and ejection. The mold temperature is 40-80°C, the injection pressure is 60-120MPa, the holding time is 5-15 seconds, and the cooling time is 20-40 seconds.

[0072] Further, the light-shielding agent includes carbon black.

[0073] [Example 1]:

[0074] In this embodiment, the weight ratio of the highly weather-resistant polypropylene fender for commercial vehicles in high-temperature areas is 65% polypropylene, 20% talc, 10% EPDM, 0.3% antioxidant (1010 / 168 compound), 1% ultraviolet absorber (UV-531), 0.7% lubricant (calcium stearate), and 3% carbon black.

[0075] In this embodiment, polypropylene, talc, EPDM, antioxidant (1010 / 168 compound), ultraviolet absorber (UV-531), lubricant (calcium stearate), and carbon black were weighed and mixed, and then fully dried. The mixed raw materials were extruded and granulated into a masterbatch through a twin-screw extruder, and then injection molding was performed.

[0076] Test process: The masterbatch is made into standard test specimens through an injection molding machine, and the density, tensile strength, simple supported beam impact strength, notched simple supported beam impact strength, heat deformation temperature, and Shore D hardness tests are carried out. The final molded products are tested for heat aging resistance, hot and cold cycle resistance, cold impact resistance, weathering resistance, and chemical medium resistance.

[0077] [Example 2]:

[0078] In this embodiment, the weight ratio of the highly weather-resistant polypropylene fender for commercial vehicles in high-temperature areas is 60% polypropylene, 25% talc, 10% EPDM, 0.2% antioxidant (1010 / 168 compound), 1.2% ultraviolet absorber (UV-531), 0.6% lubricant (calcium stearate), and 3% carbon black.

[0079] The molding method and test process are the same as those in Example 1.

[0080] [Example 3]:

[0081] In this embodiment, the weight ratio of the highly weather-resistant polypropylene fender for commercial vehicles in high-temperature areas is 58% polypropylene, 27% talc, 10% EPDM, 0.5% antioxidant (1010 / 168 compound), 1% ultraviolet absorber (UV-531), 1% lubricant (calcium stearate), and 2.5% carbon black.

[0082] The molding method and test process are the same as those in Example 1.

[0083] The test results of the high weather resistance polypropylene fender material performance in Example 1, Example 2, and Example 3 are shown in Table 1, and the test results of the product performance are shown in Table 2:

[0084] Table 1. Material properties of specific implementation cases:

[0085]

[0086] Table 2. Product performance of specific implementation cases:

[0087]

[0088] The test method is as follows:

[0089] 1.1 Density:

[0090] The test shall be carried out in accordance with the provisions of GB / T 1033-1986 (Method A).

[0091] 1.2 Tensile strength:

[0092] The test was carried out in accordance with GB / T 1040.2-2006, using a 1A type specimen at a test speed of 50 mm / min±5 mm / min.

[0093] 1.3 Simply supported beam impact strength and notched specimen simply supported beam impact strength:

[0094] The test was conducted in accordance with GB / T 1043-1993. Specimen dimensions were: Type 2 (50 mm ± 1 mm) × (6 mm ± 0.2 mm) × (4 mm ± 0.2 mm). Notch type: Type C (notch residual thickness 2 / 3d × notch width 0.8 mm ± 0.1 mm).

[0095] 1.4 Heat deformation temperature:

[0096] The test was conducted in accordance with GB / T 1634.2-2004. The specimen dimensions were: 80 mm long × 10 mm high × 4 mm thick, with a span of 64 mm. The specimens were placed upright. The maximum normal bending stress after loading was 0.46 MPa, and the relative deformation was 0.34 mm. The temperature was raised at a constant rate of 12°C / 6 min ± 1°C / 6 min.

[0097] 1.5 Shore D hardness:

[0098] The test is conducted in accordance with GB / T 2411-1980. The specimen size is a 50 mm x 50 mm square or a Φ50 mm disc. The thickness is Shore D: not less than 3 mm. The distance between each measuring point is not less than 6 mm, and the distance between each measuring point and the edge of the specimen is not less than 12 mm.

[0099] 1.6 Heat aging resistance:

[0100] After the test samples are installed to simulate the actual vehicle state, they are placed in a constant temperature box at 80℃±2℃ for 168 hours. After being taken out, the changes in the appearance of the samples are visually inspected.

[0101] 1.7 Resistance to alternating hot and cold temperatures:

[0102] After the test samples are installed to simulate the actual vehicle state, they are placed in a high and low temperature test chamber and tested for four cycles under the following conditions: -40℃×4h→RT×1h→90℃×6h→RT×1h as one cycle. After the test, the samples are taken out and visually inspected for changes in appearance.

[0103] 1.8 Cold impact resistance:

[0104] After the test sample is installed to simulate the actual vehicle state, it is placed in a low-temperature box at -40℃±2℃ for 4 hours. After freezing, the sample is taken out and a 500g steel ball is used to impact the center of the fender at a height of 800mm from the sample within 10 seconds. The changes in the appearance of the sample are visually tested.

[0105] 1.9 Weathering resistance:

[0106] Cut a sample from the product and put it into the xenon lamp aging test chamber, with the front of the product facing the lamp tube. The radiation intensity at a wavelength of 340nm is 0.55W / m 2 The blackboard temperature was 63°C, the relative humidity was 50%±5%, and a water spray cycle was performed (18 min±0.5 min of water spraying, 102 min±0.5 min of non-water spraying). The relative humidity refers to the relative humidity after the humidity reaches a stable state without water spraying. Irradiation was performed according to GB / T16422.2-1999. After 500 hours of aging, the specimens were removed and their appearance was observed. The color change was compared with the gray scale specified in GB 250-1995 and the grade was determined.

[0107] 2.0 Chemical resistance:

[0108] Wrap the product with gauze soaked in grease, polishing paraffin, protective paraffin, 120# gasoline, 0# diesel, brake fluid, engine oil, petroleum coating agent, wax remover, antifreeze, and glass cleaning fluid, place it at room temperature for 1 hour, and then put it in a constant temperature box at 80℃ for 3 hours. After taking it out, visually observe the changes in appearance (gasoline resistance is only tested at room temperature).

[0109] The ultraviolet absorber in the formula of the present invention is 0.8-1.5%, which improves the light aging resistance of the fender, solves the problem of whitening of the fender after long-term use, and is more suitable for transportation in high-temperature areas.

[0110] The antioxidant (1010 / 168 compound) added in the present invention is 0.2-0.5%, which can improve the color stability when used in high-temperature areas.

[0111] According to one aspect of the present invention, a polypropylene composite material is provided. The polypropylene composite material is prepared using the above-mentioned method for preparing the polypropylene composite material.

[0112] According to another aspect of the present invention, a fender is provided. The fender is made by injection molding a polypropylene composite material, and the polypropylene composite material is the polypropylene composite material mentioned above.

[0113] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0114] The weather resistance of the fender is significantly improved, and it can maintain stable performance for a long time in high temperature areas and is not easy to change color.

[0115] The fender has good mechanical properties, can maintain toughness under different temperature conditions, is not easy to break, and extends its service life.

[0116] This application demonstrates significant innovation and advantages compared to existing technologies in terms of material formulation, weather resistance, anti-aging system, preparation process and performance evaluation system. It is particularly suitable for manufacturing commercial vehicle fenders that need to be used in high-temperature environments and has broad market application prospects.

[0117] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used herein to describe the spatial positional relationship of a device or feature to other devices or features as shown in the figures. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figures. For example, if the device in the drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0118] In addition to the above, it should be noted that references to "one embodiment," "another embodiment," "an embodiment," and the like in this specification refer to specific features, structures, or characteristics described in conjunction with that embodiment as included in at least one embodiment generally described in this application. The appearance of the same expression in multiple places in the specification does not necessarily refer to the same embodiment. Furthermore, when a specific feature, structure, or characteristic is described in conjunction with any embodiment, it is intended that such feature, structure, or characteristic, when implemented in conjunction with other embodiments, also falls within the scope of the present invention.

[0119] In the above embodiments, the description of each embodiment has its own focus. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0120] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for preparing a polypropylene composite material, characterized in that: include: Adding at least an ultraviolet absorber, an antioxidant, an elastomer, and a light shielding agent to polypropylene, mixing, and drying to obtain an intermediate; The intermediate is extruded and granulated by a twin-screw extruder to obtain the polypropylene composite material.

2. The method for preparing a polypropylene composite material according to claim 1, wherein: At least a UV absorber, an antioxidant, an elastomer, and a light shielding agent are added to polypropylene, including: Ultraviolet absorbers, antioxidants, elastomers, light shielding agents, talc, and lubricants are added to polypropylene.

3. The method for preparing a polypropylene composite material according to claim 1, wherein: At least a UV absorber, an antioxidant, an elastomer, and a light shielding agent are added to polypropylene, including: Add hindered amine light stabilizer, ultraviolet absorber, antioxidant, elastomer, light shielding agent, talc powder and lubricant to polypropylene.

4. The method for preparing a polypropylene composite material according to claim 3, wherein: The molecular weight of the hindered amine light stabilizer is A, 4000 g / mol≥A≥1000 g / mol.

5. The method for preparing the polypropylene composite material according to claim 2, wherein: In the step of adding an ultraviolet absorber, an antioxidant, an elastomer, a light shielding agent, talc, and a lubricant to polypropylene, based on 100 parts of the total mass, the amount of the elastomer added is 5-15 parts, the amount of the ultraviolet absorber added is 0.8-1.5 parts, the amount of the antioxidant added is 0.2-0.5 parts, the amount of the light shielding agent added is 1-3 parts, the amount of the talc added is 15-30 parts, and the amount of the lubricant added is 0.5-1 part.

6. The method for preparing a polypropylene composite material according to any one of claims 1 to 3, characterized in that: The elastomer includes EPDM.

7. The method for preparing a polypropylene composite material according to any one of claims 1 to 3, characterized in that: The ultraviolet absorber includes UV-531.

8. The method for preparing a polypropylene composite material according to any one of claims 1 to 3, characterized in that: The light-shielding agent includes carbon black.

9. A polypropylene composite material, characterized in that The polypropylene composite material is prepared by the preparation method of the polypropylene composite material according to any one of claims 1 to 8.

10. A fender, made by injection molding a polypropylene composite material, characterized in that: The polypropylene composite material is the polypropylene composite material according to claim 9.

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