Ventilation grille and preparation method thereof

Abstract

The invention relates to the technical field of ventilation grilles, in particular to a ventilation grille and a preparation method thereof. The ventilation grille is formed through injection molding, and raw materials for injection molding comprise the following components in parts by weight: 35-75 parts of polypropylene resin; 15 to 35 parts of a reinforcing material; 3-8 parts of a compatilizer; 5 to 15 parts of a toughening agent; 0.5 to 1.5 parts of a nucleating agent; 1 to 3 parts of an antioxidant; 1-3 parts of a light stabilizer; and 0.3 to 0.8 part of a lubricant. Through the component proportion, the rigidity and the toughness of the ventilation grille can be guaranteed, the strength and the heat resistance of the grille are improved, the light aging resistance of the grille in harsh external environments such as high temperature and strong ultraviolet rays is enhanced, the color stability of the grille is improved, and the service life of the grille is prolonged. According to the preparation method of the ventilation grille, mass production of the ventilation grille can be rapidly achieved.

Description

Technical Field

[0001] This invention relates to the field of ventilation grille technology, and in particular to a ventilation grille and its manufacturing method. Background Technology

[0002] Vehicle ventilation grilles are typically installed at the front of a vehicle, and their main function is to provide cooling air to the engine compartment or other components that require heat dissipation. When the vehicle is in motion, air passes through the ventilation grille, helping the radiator dissipate heat from the engine coolant and other components, preventing parts from malfunctioning due to overheating and ensuring the normal operation of the vehicle.

[0003] Ventilation grilles are typically made of polypropylene. Prolonged exposure to sunlight causes photoaging, damaging the polypropylene's molecular structure and leading to color changes such as whitening or yellowing. Furthermore, high temperatures and humidity accelerate this aging process, making the whitening more pronounced. This not only affects the vehicle's appearance and reduces customer satisfaction but can also make the grille surface rough, reducing ventilation efficiency. Additionally, color fading may expose internal metal components, increasing wind resistance and corrosion risks. Summary of the Invention

[0004] The purpose of this invention is to provide a ventilation grille that can withstand harsh outdoor environments such as high temperature, strong ultraviolet radiation, day and night temperature difference, rain, and chemicals (such as car wash liquid and bird droppings) with high weather resistance, while having sufficient mechanical strength to protect the engine compartment and meet the vehicle's service life.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] A ventilation grille, formed by injection molding, wherein the raw material for injection molding comprises the following components in parts by weight:

[0007] Polypropylene resin: 35-75 parts;

[0008] Reinforcing material: 15-35 parts;

[0009] Compatibilizer: 3-8 parts;

[0010] Toughening agent: 5-15 parts;

[0011] Nucleating agent: 0.5-1.5 parts;

[0012] Antioxidant: 1-3 parts;

[0013] Light stabilizer: 1-3 parts;

[0014] Lubricant: 0.3-0.8 parts.

[0015] Preferably, the polypropylene resin is a mixture of block copolymer polypropylene resin and random copolymer polypropylene resin.

[0016] Preferably, the block copolymer polypropylene resin and the random copolymer polypropylene resin are compounded at a mass ratio of 60:40.

[0017] Preferably, the reinforcing material is chopped alkali-free glass fiber.

[0018] Preferably, the chopped alkali-free glass fiber has a diameter of 9-13 μm and a chopped length of 3-25 mm.

[0019] Preferably, the compatibilizer is maleic anhydride-grafted polypropylene.

[0020] Preferably, the toughening agent is an ethylene-octene copolymer.

[0021] Preferably, the antioxidant is a mixture of antioxidant 1010 and antioxidant 168.

[0022] Preferably, the light stabilizer is a mixture of amine-resistant light stabilizer 770 and amine-resistant light stabilizer 944.

[0023] Another objective of this invention is to provide a method for manufacturing a ventilation grille, which can quickly achieve mass production of the aforementioned ventilation grille.

[0024] To achieve this objective, the present invention adopts the following technical solution:

[0025] A method for preparing a ventilation grille, characterized in that it is used to prepare the ventilation grille according to any one of claims 1-9, the method for preparing the ventilation grille comprising the following steps:

[0026] S1. Weigh each component according to the weight ratio, mix them evenly and dry them to obtain the raw material;

[0027] S2. Granulate the mixed and dried raw materials;

[0028] S3. The granulated raw material is fed into the injection molding machine for injection molding.

[0029] The beneficial effects of this invention are:

[0030] This invention discloses a ventilation grille manufactured by injection molding. The injection molding material comprises the following components in parts by weight: polypropylene resin: 35-75 parts; reinforcing material: 15-35 parts; compatibilizer: 3-8 parts; toughening agent: 5-15 parts; nucleating agent: 0.5-1.5 parts; antioxidant: 1-3 parts; light stabilizer: 1-3 parts; lubricant: 0.3-0.8 parts. Through the above component ratio, not only can the rigidity and toughness of the ventilation grille be guaranteed, and the strength and heat resistance of the grille be improved, but also the light aging resistance of the grille under harsh external environments such as high temperature and strong ultraviolet radiation is enhanced, and the color stability and service life of the grille are improved.

[0031] The method for manufacturing ventilation grilles disclosed in this invention can quickly achieve mass production of the aforementioned ventilation grilles. Detailed Implementation

[0032] The present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the present invention are shown, not all of the structures.

[0033] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0034] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0035] In the description of this embodiment, the terms "upper," "lower," "right," etc., refer to the indicated orientation or positional relationship, and are only for the convenience of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. In addition, the terms "first" and "second" are only used for distinction in description and have no special meaning.

[0036] This invention discloses a ventilation grille, which is injection molded. The raw materials for injection molding include the following components in parts by weight: polypropylene resin: 35-75 parts; reinforcing material: 15-35 parts; compatibilizer: 3-8 parts; toughening agent: 5-15 parts; nucleating agent: 0.5-1.5 parts; antioxidant: 1-3 parts; light stabilizer: 1-3 parts; lubricant: 0.3-0.8 parts. Through the above component ratio, not only can the rigidity and toughness of the ventilation grille be guaranteed, and the strength and heat resistance of the grille be improved, but also the light aging resistance of the grille under harsh external environments such as high temperature and strong ultraviolet radiation be enhanced, and the color stability and service life of the grille be improved.

[0037] In some embodiments, the polypropylene resin is a mixture of block copolymer polypropylene resin and random copolymer polypropylene resin, wherein the block copolymer polypropylene resin and the random copolymer polypropylene resin are compounded in a mass ratio of 60:40. It is understood that using both block copolymer polypropylene resin and random copolymer polypropylene resin in this ratio can improve impact resistance and increase toughness while providing material rigidity, heat resistance, and basic mechanical properties.

[0038] In some embodiments, the reinforcing material is chopped alkali-free glass fiber to improve the strength, rigidity, and heat resistance of the grid. In some specific embodiments, the diameter of the chopped alkali-free glass fiber is 9-13 μm, and the chopped length is 3-25 mm. It is understood that alkali-free glass fiber (also known as E-glass fiber) is an aluminoborosilicate glass fiber with an alkali metal oxide content of less than 0.8%. Domestic standards require an alkali content of no more than 0.5%, while international standards typically control it at around 1%. It possesses advantages such as high strength, excellent chemical stability, and good electrical insulation properties as its core characteristics. The use of chopped glass fiber results in good filament bundle structure and low lint content. It exhibits excellent dry flowability, which is highly advantageous for continuous feeding, and the glass fiber is distributed very evenly in the product. The chopped length can be 3 mm, 4.5 mm, 6 mm, 12 mm, 25 mm, etc. This gives the material high-temperature stability, low-temperature crack resistance, and fatigue resistance.

[0039] In some embodiments, the compatibilizer is maleic anhydride-grafted polypropylene, used to improve the compatibility between polypropylene and glass fiber and enhance interfacial bonding. Maleic anhydride-grafted polypropylene can serve as a highly efficient compatibilizer, significantly improving the interfacial bonding between polypropylene and non-polar or inorganic materials (such as nylon, glass fiber, fillers, etc.), thereby greatly enhancing the mechanical strength, impact toughness, and processing stability of the composite material.

[0040] In some embodiments, the toughening agent is an ethylene-octene copolymer, which can form fine elastomer particles that are uniformly dispersed in the rigid polypropylene matrix, efficiently inducing crazes and shear bands, thereby absorbing and dispersing a large amount of impact energy. While significantly improving the impact toughness and low-temperature toughness of the material, it has a relatively small impact on the rigidity and strength of the matrix, and has good processing fluidity.

[0041] In some embodiments, the nucleating agent is a polypropylene-specific nucleating agent, such as a sorbitol-based nucleating agent or a β-crystalline nucleating agent. The added lubricant is calcium stearate, which improves processing fluidity. In this embodiment, Millad 3998 is selected as the nucleating agent, which can significantly improve the transparency (e.g., reduce haze) and surface gloss of the product by promoting polypropylene crystallization and refining grains. It can also improve the rigidity, impact toughness, and heat distortion temperature of the material, increase the crystallization temperature, shorten the molding cycle, and thus improve processing efficiency.

[0042] In some embodiments, the antioxidant is a mixture of antioxidant 1010 and antioxidant 168 to prevent oxidative degradation during processing and use. The two produce a superior synergistic stabilizing effect: 1010, as the primary antioxidant, inhibits material aging by capturing free radicals, while 168, as a secondary antioxidant, decomposes hydrogen peroxide generated during processing. Together, they provide highly efficient all-around protection for the ventilation grille, significantly preventing thermal oxidative degradation during high-temperature processing and long-term use, effectively maintaining the material's mechanical properties and inhibiting yellowing, thus extending the product's service life. The light stabilizer is a mixture of amine-resistant light stabilizer 770 and amine-resistant light stabilizer 944. 770, as a low molecular weight product, migrates rapidly and takes effect quickly, while 944, as a high molecular weight product, has excellent durability. Together, they effectively interrupt the chain reaction of polymer degradation induced by ultraviolet light through multiple mechanisms such as continuous free radical capture and hydrogen peroxide decomposition, thereby providing the ventilation grille with excellent long-term weather resistance, significantly preventing problems such as surface chalking, embrittlement, discoloration, and decreased mechanical properties during outdoor use, and greatly extending its service life. Meanwhile, the high content of antioxidants (1-3 parts) and light stabilizers (1-3 parts) directly addresses and solves the core problem of intense thermo-oxidative aging and UV aging in high-temperature regions. The high dose of antioxidants effectively inhibits thermo-oxidative aging during processing and use, preventing molecular chain breakage and performance degradation; while the ample light stabilizers provide top-level UV radiation protection, blocking photodegradation at its source. This enhanced stabilization system works synergistically to provide maximum protection for ventilation grilles used in harsh environments (such as long-term outdoor exposure or high-temperature conditions), whereas ordinary grilles typically do not contain or only contain small amounts of these additives, failing to meet the long-life requirements of such harsh environments.

[0043] Another objective of this invention is to provide a method for manufacturing a ventilation grille, which can quickly achieve mass production of the aforementioned ventilation grille.

[0044] To achieve this objective, the present invention adopts the following technical solution.

[0045] A method for preparing a ventilation grille, comprising the following steps:

[0046] S1. Weigh each component according to the weight ratio, mix them evenly and dry them to obtain the raw material;

[0047] S2. Granulate the mixed and dried raw materials;

[0048] S3. The granulated raw material is fed into the injection molding machine for injection molding.

[0049] In step S1, the weighed components are added to a mixer for stirring, resulting in a relatively uniform and loose mixture that is easy to discharge, clean, and produce high efficiency. In step S2, the dried raw materials are fed into a twin-screw extruder for granulation, ensuring highly uniform dispersion and distribution of the multi-components, providing greater shear force, and achieving effective compatibility. Twin-screw extruders are typically equipped with exhaust ports connected to a vacuum pump, which can extract moisture, low-molecular-weight volatiles, and some reaction byproducts from the molten material. It also ensures that the temperature, screw speed, and feeding rate of each section can be independently and precisely controlled, facilitating subsequent injection molding.

[0050] The injection molding process includes four steps: melting and plasticizing, injection filling, cooling and solidification, and demolding and ejection. The barrel temperature is set as follows: 200-220℃ for the front section, 210-230℃ for the middle section, and 180-200℃ for the rear section. This gradient setting ensures stable material delivery in the rear section, thorough melting and mixing in the middle section, and the formation of a uniform, gas-free melt in the front section. The injection pressure is 80-120MPa, and the injection speed is 30-60cm³ / s to ensure rapid and complete mold filling, avoiding appearance or structural defects caused by premature cooling of the melt front. The holding time is 5-15 seconds, the mold temperature is controlled at 40-60℃, and the cooling time is 20-40 seconds, until the product has sufficient rigidity and strength for ejection.

[0051] Understandably, this preparation method ensures the uniform distribution of each component through precise weight ratios, followed by efficient mixing and drying to effectively remove moisture. Subsequently, a granulation process homogenizes the material and increases its bulk density, ultimately enabling rapid and precise product manufacturing through injection molding. This process offers significant advantages such as ease of operation, high production efficiency, and stable and controllable product quality, making it particularly suitable for large-scale industrial production needs.

[0052] To more intuitively illustrate the performance of the ventilation grille of the present invention, several specific embodiments will be disclosed below.

[0053] Example 1:

[0054] The raw materials for injection molding of the ventilation grille of the present invention have the following weight ratios: 36 parts block copolymer polypropylene resin, 24 parts random copolymer polypropylene resin, 20 parts chopped alkali-free glass fiber, 5 parts compatibilizer, 10 parts toughening agent ethylene-octene copolymer (POE), 0.5 parts polypropylene-specific nucleating agent, 2 parts antioxidant (1010 / 168 compound), 2 parts light stabilizer, and 0.5 parts lubricant.

[0055] Example 2:

[0056] The raw materials for injection molding of the ventilation grille of the present invention have the following weight ratios: 30 parts block copolymer polypropylene resin, 20 parts random copolymer polypropylene resin, 30 parts chopped alkali-free glass fiber, 5 parts compatibilizer, 8 parts toughening agent ethylene-octene copolymer (POE), 1.5 parts polypropylene-specific nucleating agent, 2 parts antioxidant (1010 / 168 compound), 3 parts light stabilizer, and 0.5 parts lubricant.

[0057] Example 3:

[0058] The raw materials for injection molding of the ventilation grille of the present invention have the following weight ratios: 30 parts block copolymer polypropylene resin, 20 parts random copolymer polypropylene resin, 25 parts chopped alkali-free glass fiber, 8 parts compatibilizer, 10 parts toughening agent ethylene-octene copolymer (POE), 1 part polypropylene-specific nucleating agent, 3 parts antioxidant (1010 / 168 compound), 2.5 parts light stabilizer, and 0.5 parts lubricant.

[0059] The ventilation grilles in the above three embodiments are all prepared using the ventilation grille preparation method provided by the present invention. The ventilation grilles with different component ratios provided in the above three embodiments can withstand xenon lamp aging for more than 1500 hours according to the test method of GB / T16422.2-2022 (cycle number 4 - narrow band), and there is no significant discoloration in the equivalent real vehicle within one year of use in high-temperature areas.

[0060] Specifically, the test results of the ventilation grille material performance in the above three embodiments are shown in Table 1, and the test results of the finished ventilation grille performance are shown in Table 2:

[0061] Table 1: Test Results of Ventilation Grille Material Properties

[0062]

[0063] Table 2: Performance Test Results of Ventilation Grilles

[0064]

[0065] The test methods in Tables 1 and 2 are as follows:

[0066] Test Method 1.1: Density Test. The test shall be conducted in accordance with the provisions of GB / T1033-1986 (Method A).

[0067] Test Method 1.2: Tensile Strength Test. The test shall be conducted in accordance with GB / T1040.2-2006, using type 1A specimens, and the test speed shall be 50 mm / min ± 5 mm / min.

[0068] Test Method 1.3: Bending Strength Test. The test shall be conducted in accordance with GB / T9341-2008. The specimen dimensions are 80 mm ± 2 mm in length, 10 mm ± 0.2 mm in width, and 4 mm ± 0.2 mm in thickness. The test span is 16 ± 1 times the specimen thickness, and the test speed is 2.0 mm / min ± 0.4 mm / min.

[0069] Test Method 1.4: Impact Strength Test of Simply Supported Beam. The test shall be conducted in accordance with the provisions of GB / T1043-1993. The specimen size is: Type 2 (50mm±1mm)×(6mm±0.2mm)×(4mm±0.2mm).

[0070] Test Method 1.5: Ball Indentation Hardness Test. The test shall be conducted according to GB / T3398.1-2008. Specimen size: 50mm×50mm×4mm or Φ50mm×4mm, indenter diameter 5mm, test load 132N, holding load for 30s.

[0071] Test Method 1.6: Heat Deflection Temperature Test. The test shall be conducted according to GB / T1634.2-2004. Specimen dimensions: length 80mm × height 10mm × thickness 4mm, span 64mm. During the test, the specimen shall be placed upright. The maximum bending normal stress of the specimen under load is 0.46MPa, the relative deformation is 0.34mm, and the heating rate is 12℃ / 6min ± 1℃ / 6min, with a constant heating rate.

[0072] Test Method 1.7: Heat Resistance Test. Under the same assembly conditions as the actual vehicle, the product was placed in a constant temperature chamber at 110℃ for 24h±2h, then removed and placed at room temperature for 30min. The surface of the product was then visually observed for any changes.

[0073] Test Method 1.8: Cold Resistance Test. Place the product in a refrigerator and leave it at -40℃±2℃ for 24h±2h. Then remove it and leave it at room temperature for 30min. Finally, visually inspect the changes in the appearance of the product.

[0074] Test Method 1.9: Chemical Resistance Test. Wrap the product in gauze soaked in lubricating grease, polishing paraffin wax, protective paraffin wax, 120# gasoline, 0# diesel, brake fluid, engine oil, petroleum coating agent, wax remover, antifreeze, and glass cleaner, respectively. Place them at room temperature for 1 hour, then place them in an 80℃ constant temperature chamber for 3 hours. After removing them, visually inspect the changes in appearance.

[0075] Test Method 1.10: Light Aging Resistance Test. A sample is cut from the product and placed in a xenon lamp aging test chamber with the front of the product facing the lamp. Irradiation is performed according to GB / T16422.2-1999. After the specified aging time of 1500 hours, the sample is removed, its appearance is observed, and its grade is determined by comparing it with the gray scale card specified in GB / T250-2008.

[0076] Test Method 1.11: Heat Aging Resistance Test. Place one product or a sample taken from the product in a constant temperature chamber at 150℃±2℃ for a specified time. After the test, remove the product and visually inspect the appearance quality of the sample. The sample should not exhibit the aging decomposition phenomenon characteristic of polypropylene.

[0077] It is evident that the ventilation grille material in the above embodiments of the present invention possesses excellent strength and heat resistance. Under the same assembly conditions as the actual vehicle, the finished ventilation grille samples from the three embodiments, after being placed in a constant temperature chamber at 110℃ for 24h±2h and then placed at room temperature for 30min, showed no abnormal phenomena such as deformation, discoloration, or stickiness. Similarly, when the samples were placed in a refrigerator at -40℃±2℃ for 24h±2h and then placed at room temperature for 30min, no cracks or other abnormal phenomena appeared, demonstrating excellent resistance to high temperatures, large temperature differences, and low temperatures. Furthermore, when the samples were wrapped in gauze soaked in lubricating grease, polishing paraffin wax, protective paraffin wax, 120# gasoline, 0# diesel fuel, brake fluid, engine oil, petroleum coating agent, wax remover, antifreeze, and glass cleaner, respectively, and placed at room temperature for 1h, followed by placement in an 80℃ constant temperature chamber for 3h, no discoloration or stickiness was observed. Finally, when the samples were placed in a xenon lamp aging test chamber with the front of the sample facing the lamp tube, no abnormal phenomena were observed. Irradiation was performed according to GB / T16422.2-1999. After reaching the specified aging time of 1500 hours, the samples were removed and observed for any abnormalities such as deformation, discoloration, chalking, or cracking. The grayscale color fastness was compared to grade 4-5 using a gray scale card as specified in GB / T250-2008. The samples were then placed in a constant temperature chamber at 150℃±2℃ for the specified time. After the test, the samples were visually inspected and showed excellent performance, exhibiting no delamination or breakage for up to 500 hours.

[0078] Obviously, the ventilation grille of the present invention has the performance to prevent surface color changes and phenomena such as whitening and yellowing under high temperature, large temperature difference and low temperature conditions. It is a highly weather-resistant ventilation grille. Vehicles using this ventilation grille will not have their appearance affected by the discoloration or whitening of the ventilation grille, thus improving user satisfaction. It can ensure the smooth surface of the ventilation grille, ensure ventilation efficiency, and also has the effect of resisting chemical corrosion. It has the effect of protecting itself and the internal structure of the vehicle, thereby avoiding the increase of vehicle wind resistance and the corrosion of the vehicle body structure caused by the corrosion and deformation of its own structure.

[0079] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art will be able to make various obvious changes, readjustments, and substitutions without departing from the scope of protection of the present invention. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A ventilation grille, formed by injection molding, characterized in that, The raw material for injection molding comprises the following components in parts by weight: Polypropylene resin: 35-75 parts; Reinforcing material: 15-35 parts; Compatibilizer: 3-8 parts; Toughening agent: 5-15 parts; Nucleating agent: 0.5-1.5 parts; Antioxidant: 1-3 parts; Light stabilizer: 1-3 parts; Lubricant: 0.3-0.8 parts.

2. The ventilation grille according to claim 1, characterized in that, The polypropylene resin is a mixture of block copolymer polypropylene resin and random copolymer polypropylene resin.

3. The ventilation grille according to claim 2, characterized in that, The block copolymer polypropylene resin and the random copolymer polypropylene resin are compounded at a mass ratio of 60:

40.

4. The ventilation grille according to claim 1, characterized in that, The reinforcing material is chopped alkali-free glass fiber.

5. The ventilation grille according to claim 4, characterized in that, The chopped alkali-free glass fibers have a diameter of 9-13 μm and a chopped length of 3-25 mm.

6. The ventilation grille according to claim 1, characterized in that, The compatibilizer is maleic anhydride-grafted polypropylene.

7. The ventilation grille according to claim 1, characterized in that, The toughening agent is an ethylene-octene copolymer.

8. The ventilation grille according to claim 1, characterized in that, The antioxidant is a mixture of antioxidant 1010 and antioxidant 168.

9. The ventilation grille according to claim 1, characterized in that, The light stabilizer is a mixture of amine-resistant light stabilizer 770 and amine-resistant light stabilizer 944.

10. A method for preparing a ventilation grille, characterized in that, The method for preparing the ventilation grille according to any one of claims 1-9 includes the following steps: S1. Weigh each component according to the weight ratio, mix them evenly and dry them to obtain the raw material; S2. Granulate the mixed and dried raw materials; S3. The granulated raw material is fed into the injection molding machine for injection molding.

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