A polypropylene composite material for a lightweight radar cover plate and a preparation method thereof

Abstract

This invention discloses a lightweight polypropylene composite material for radar covers and its preparation method. The composite material is prepared from the following components: 50.7-55.6 parts polypropylene, 10-20 parts high heat-resistant elastomer, 28-33 parts high aspect ratio mineral filler, 0.1-0.2 parts antioxidant, 0.1-0.2 parts lubricant, and 1-1.5 parts color masterbatch; the melting temperature of the high heat-resistant elastomer is 117-120℃; the aspect ratio of the high aspect ratio mineral filler is (80-120):1. This invention also discloses the preparation method of this composite material and its application in the preparation of radar covers for new energy vehicles. Through the synergistic effect of the high heat-resistant elastomer and the high aspect ratio mineral filler, this invention enables the composite material to possess low density, high rigidity, high heat resistance, low coefficient of linear expansion, and excellent dielectric properties, thus meeting the requirements for use in radar covers for new energy vehicles.

Description

Technical Field

[0001] This invention relates to the field of polymer material modification technology, and in particular to a lightweight polypropylene composite material for radar cover plates and its preparation method. Background Technology

[0002] As my country's new energy vehicles rapidly develop towards advanced intelligent driving and lightweight design, millimeter-wave radar, as a core sensor for environmental perception, places stringent requirements on the materials used for protective covers, particularly regarding installation accuracy and signal transmittance. Radar covers must possess sufficient mechanical strength to resist deformation, maintain dimensional stability across high and low temperature ranges, and also achieve good manufacturing economy.

[0003] Currently, PC / PET-MD15 alloy material is widely used in the field of radar covers for new energy vehicles. This material uses polycarbonate and polyethylene terephthalate alloy as the matrix and introduces 15wt% mineral filler. Its advantages are: high tensile strength and flexural modulus, which can effectively withstand external deformation; good heat resistance, which can adapt to high temperature exposure and the thermal environment near the power system; and low coefficient of linear expansion, which matches well with the expansion characteristics of the vehicle body bracket, thus ensuring the detection accuracy of the radar under different temperature conditions.

[0004] However, this material has gradually revealed significant shortcomings in actual mass production. First, its relatively high density (approximately 1.34 g / cm³) hinders the achievement of vehicle lightweighting goals, thus impacting the improvement of driving range. Second, the processing temperature of this material is relatively high (approximately 260-280℃), placing high demands on the heating system and molds during injection molding, leading to increased energy consumption and prolonged molding cycles. Third, the dielectric properties of this alloy system (dielectric constant approximately 3.2, dielectric loss approximately 0.015@20GHz) still have room for improvement; lower dielectric constant and dielectric loss are beneficial for improving the signal transmittance of millimeter-wave radar.

[0005] Furthermore, in the field of mineral filler-modified polymer alloys, the introduction of fillers is often a double-edged sword. As described in patent CN120289975A, while adding talc to PC / PET alloys can improve the material's rigidity, heat resistance, and reduce the coefficient of linear expansion, the agglomeration of talc and its alkaline properties can lead to surface defects such as pinholes and unevenness, and even accelerate the degradation of the alloy material. This indicates that how to maintain the advantages of mineral filler modification while overcoming its negative impacts remains a key technical challenge in this field.

[0006] Therefore, it is necessary to seek a new alternative material that can maintain similar dimensional stability while having better lightweight effect, lower processing temperature and better dielectric properties, so as to better meet the technical requirements of the continuous upgrading of radar covers for new energy vehicles. Summary of the Invention

[0007] The purpose of this invention is to provide a lightweight polypropylene composite material for radar cover plates and a method for preparing the same. The specific technical solution for achieving the above-mentioned objective is as follows: In a first aspect, the present invention provides a lightweight polypropylene composite material for radar cover plates, which is prepared from the following components in parts by weight: 50.7-55.6 parts of polypropylene, 10-20 parts of high heat-resistant elastomer, 28-33 parts of high aspect ratio mineral filler, 0.1-0.2 parts of antioxidant, 0.1-0.2 parts of lubricant, and 1-1.5 parts of colorant; The melting temperature of the high heat-resistant elastomer is 117~120℃; The diameter-to-thickness ratio of the high diameter-to-thickness mineral filler is (80-120):1.

[0008] Furthermore, the polypropylene is homopolymer polypropylene, copolymer polypropylene, or a mixture of homopolymer and copolymer polypropylene, and has a melt index of 3-100 g / 10 min at 230℃ / 2.16 kg.

[0009] Furthermore, the high heat-resistant elastomer is an ethylene-octene block copolymer, selected from one or more of Dow Engage 8677, Engage 11567, Engage 11527 or POE 11547.

[0010] Furthermore, the high aspect ratio mineral filler is one or more of talc or mica.

[0011] Furthermore, the antioxidant includes a primary antioxidant and a secondary antioxidant, wherein the primary antioxidant is one of 1010, 1076, and 3114, and the secondary antioxidant is 168; the lubricant is one or more of calcium stearate, zinc stearate, stearate ester, erucamide, and oleamide.

[0012] Secondly, the present invention provides a method for preparing the above-mentioned lightweight radar cover plate polypropylene composite material, comprising the following steps: S1. Mix polypropylene, high heat-resistant elastomer, antioxidant, lubricant and colorant evenly according to the formula; S2. Using a side-feeding method, high aspect ratio mineral fillers are incorporated into the mixture in S1, and then melted, extruded, air-dried, and granulated by a twin-screw extruder to obtain the polypropylene composite material.

[0013] Furthermore, in step S2, the extrusion temperatures of the twin-screw extruder are as follows: Zone 1 100±10℃, Zone 2 160±10℃, Zone 3 180±10℃, Zones 4 to 9 200±10℃, and the die head 210±10℃; the screw speed is 500-600 r / min, the length-to-diameter ratio is (48-58):1, the vacuum degree is -0.05~-0.1MPa, and the extruder head is equipped with a single-layer 80-120 mesh filter.

[0014] Furthermore, in step S1, high-speed stirring is used for mixing, with a stirring speed of 600-800 r / min and a mixing time of 5-8 min.

[0015] Thirdly, the present invention provides an application of the above-mentioned polypropylene composite material or the polypropylene composite material prepared by the above-mentioned preparation method in the preparation of radar cover plates for new energy vehicles.

[0016] Furthermore, the radar cover is a millimeter-wave radar protective cover.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. Significant weight reduction effect: The polypropylene composite material prepared by this invention has a density of 1.09-1.15 g / cm³, which is about 15-20% lower than the existing PC / PET-MD15 material (density 1.34 g / cm³). This can effectively achieve the weight reduction target of radar cover and help improve the driving range of new energy vehicles.

[0018] 2. Excellent heat resistance and dimensional stability: The composite material of this invention has a flexural modulus greater than 3300 MPa, a heat distortion temperature greater than 120℃, a Vicat softening temperature greater than 135℃, and a linear coefficient of thermal expansion less than 50 × 10⁻⁶. -6 With a temperature range of -30℃ to 100℃ and a molding shrinkage rate of less than 0.5%, the radar cover plate meets the requirements for dimensional stability and rigidity over a wide temperature range.

[0019] 3. Excellent dielectric properties: The composite material of this invention has a dielectric constant of 2.8-2.9 and a dielectric loss of 0.006-0.007 at a frequency of 20GHz, which are better than PC / PET-MD15 material (dielectric constant 3.2, dielectric loss 0.015), which is beneficial to improving the signal transmittance and detection accuracy of millimeter-wave radar and reducing signal transmission loss.

[0020] 4. Good processing economy: This invention uses polypropylene as the matrix and the processing temperature is about 200-210℃, which is much lower than the 260-280℃ of PC / PET alloy, which helps to reduce manufacturing costs. Detailed Implementation

[0021] The technical solutions of this disclosure will be clearly and completely described below with reference to specific embodiments. However, those skilled in the art will understand that the embodiments described below are only some embodiments of this disclosure, not all embodiments, and are only used to illustrate this disclosure, and should not be regarded as limiting the scope of this disclosure. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0022] The sources and specifications of the raw materials used in the following examples and comparative examples are as follows: Polypropylene: Copolymer polypropylene, manufactured by SK Corporation of South Korea, brand name is copolymer PP BX3800, melt index is 30g / 10min at 230℃ / 2.16kg.

[0023] High heat-resistant polyolefin elastomer: ethylene-octene block copolymer, manufactured by Dow Chemical, brand name Engage 11547, melt flow rate 5 g / 10 min, test conditions 190℃ / 2.16 kg; the actual measured melting point of Engage 11547 was 117 °C, as described in Dow TDS using DSC (differential scanning calorimetry).

[0024] Common polyolefin elastomer: Manufacturer: Dow Chemical, Trademark name: Engage 8200, Melt flow rate: 5 g / 10 min, Test conditions: 190 °C / 2.16 kg; The actual measured melting point of Engage 8200 was 59 °C, as described in Dow TDS using DSC (Differential Scanning Calorimeter).

[0025] High aspect ratio mica: Manufacturer is Chuzhou Wanqiao Sericite Co., Ltd., product name is CJ-A5, produced using the sedimentation method. D50 and laser method L D50 The particle size of mica CJ-A5 was measured, and the test results were D50: 2.7 μm and D50: 12.1 μm, respectively. The aspect ratio was calculated using the formula 3*3.14 / 2*(L). D50 -S D50 ) 2 The aspect ratio of this mica was calculated to be 94.59.

[0026] Talc powder: Manufacturer is Yingge Porcelain (Wuhu) Co., Ltd., product name is Steamic T1CN, talc powder mesh size is 3000 mesh; it is produced by sedimentation method. D50 and laser method L D50The particle size of Steamic T1CN talc was determined, and the results were D50: 1.9 μm and D50: 5.5 μm, respectively. The aspect ratio was calculated using the formula 3*3.14 / 2*(L). D50 -S D50 ) 2 The aspect ratio of this talc powder was calculated to be 39.47.

[0027] Main antioxidant: Antioxidant 1010; Co-antioxidant: Antioxidant 168; Lubricant: Erucamide; Colorant: Black masterbatch, carrier is PP resin, carbon black content 50wt%.

[0028] Composite material preparation methods According to the proportions in Table 1, add polypropylene resin, elastomer, antioxidant, lubricant and color masterbatch into a high-speed mixer and stir at a speed of 500-800 r / min for 5-8 minutes to make it uniformly mixed.

[0029] The side-feeding method is adopted, and the mineral filler (high aspect ratio mica or ordinary talc powder) is added from the side of the twin-screw extruder to the feed port, and merges with the above-mentioned mixed melt.

[0030] Polypropylene composite material for radar cover plates is obtained after melting, extrusion, air drying, and granulation in a twin-screw extruder. The extrusion temperatures of each extrusion zone in the twin-screw extruder are as follows: Zone 1 100±10℃, Zone 2 160±10℃, Zone 3 180±10℃, Zone 4 200±10℃, Zone 5 200±10℃, Zone 6 200±10℃, Zone 7 200±10℃, Zone 8 200±10℃, Zone 9 200±10℃, and die head 210±10℃. The screw speed is 500-600 r / min, the length-to-diameter ratio of the twin-screw extruder is (48-58):1, the vacuum degree during extrusion is -0.05~-0.1MPa, and the extruder head is equipped with a single-layer 80-120 mesh filter screen, with a screen changing frequency of 4 hours / time.

[0031] Within the above parameter range, those skilled in the art can make appropriate adjustments according to the equipment condition and raw material characteristics. The following examples and comparative examples all use the above preparation method, wherein the high-speed mixer stirring speed is 500 r / min, and the mixing time is 10 min; the actual temperature settings for each section of the twin-screw extruder are: Zone 1 100℃, Zone 2 160℃, Zone 3 180℃, Zone 4 200℃, Zone 5 200℃, Zone 6 200℃, Zone 7 200℃, Zone 8 200℃, Zone 9 200℃, and Die Head 210℃; the screw speed is 550 r / min; the length-to-diameter ratio of the twin-screw extruder is 52:1; the vacuum degree during extrusion is -0.08 MPa; the extruder head filter screen mesh size is 100 mesh; and the screen changing frequency is 4 h / time.

[0032] According to the proportions in Table 1, the polypropylene composite materials of Examples 1-3 and Comparative Examples 1-2 were prepared using the above preparation method.

[0033] Table 1. Formulation composition (parts by weight) of Examples 1-3 and Comparative Examples 1-2

[0034] The radar covers prepared in Examples 1-3 and Comparative Examples 1-2 were subjected to relevant performance tests using polypropylene material. The test data are shown in Table 2. The specific test methods are as follows: 1. Density: Tested at 23°C according to ISO 1183 standard.

[0035] 2. Tensile strength: Tested according to ISO 527 standard at 23°C with a tensile speed of 50 mm / min.

[0036] 3. Cantilever beam notched impact strength: Tested according to ISO 180 standard at 23℃, type A notch.

[0037] 4. Flexural modulus: Tested according to ISO 178 standard at 23℃ and 100℃ respectively, at a test speed of 2mm / min.

[0038] 5. Heat distortion temperature: Tested according to ISO 75-2 standard under a load of 0.45 MPa.

[0039] 6. Vicat softening temperature: Tested according to ISO 306 standard, under conditions of 10N load and heating rate of 120℃ / h.

[0040] 7. Linear thermal expansion coefficient: Tested in accordance with ISO 11359-2 within a temperature range of -30℃ to 100℃, and the linear thermal expansion coefficient in the flow direction is recorded.

[0041] 8. Low-temperature drop ball impact: According to PV3989 standard, under -30℃ conditions, a 500g drop ball from a height of 450mm is used for testing, and the sample is observed to see if it cracks.

[0042] 9. Molding shrinkage: Tested after being placed at 23°C for 72 hours according to ISO 294-4 standard.

[0043] 10. Dielectric constant and dielectric loss: Tested at 20 GHz according to GB / T 1409 standard.

[0044] Table 2 Performance test results of Examples 1-3 and Comparative Examples 1-2

[0045] Note: The criteria for determining no cracking are: no cracking, no breakage, and no stress whitening.

[0046] As can be seen from the product test results of the various embodiments and comparative examples in Table 2, the polypropylene composite material for radar cover prepared by the present invention, which utilizes the synergistic incorporation of high heat-resistant elastomer and high aspect ratio mica, has a flexural modulus greater than 3300 MPa, a heat distortion temperature above 120℃, a Vicat softening temperature above 135℃, and also has a low linear thermal expansion coefficient and molding shrinkage rate. Furthermore, its low-temperature drop ball impact performance meets the basic requirements of exterior parts.

[0047] Further comparison of Example 2 with Comparative Examples 1 and 2 reveals that: Comparative Example 1, using ordinary POE and ordinary talc, exhibits significantly inferior flexural modulus, heat resistance, and coefficient of linear expansion compared to Example 2; although Comparative Example 2 uses high aspect ratio mica, its high-temperature flexural modulus and heat resistance are still significantly lower than those of Example 2 due to the use of ordinary POE. This indicates that neither high aspect ratio mica alone nor high heat-resistant POE alone can achieve ideal overall performance; only through the synergistic effect of both can high heat resistance and low linear expansion be achieved while maintaining high modulus, thus meeting the stringent requirements of radar cover plates.

[0048] Comparison with existing engineering materials Examples 1-3 were compared with PC / PET-MD15, a commonly used material for existing radar covers, and the results are shown in Table 3.

[0049] Table 3 Performance comparison between Examples 1-3 and PC / PET-MD15

[0050] Note: The performance data for PC / PET-MD15 are based on the Covestro PC / PET-MD15 UT235 grade.

[0051] As can be seen from Table 3: Lightweight effect: The density of the polypropylene composite material of the present invention is 1.09-1.15 g / cm³, which is about 15-20% lower than that of PC / PET-MD15 (1.34 g / cm³), effectively reducing the weight of parts used in radar cover plates.

[0052] Heat resistance and dimensional stability: The heat distortion temperature (122-130℃), Vicat softening temperature (136-148℃), and linear thermal expansion coefficient (39-46×10⁻⁶) of this invention are as follows. -6 The temperature range (°C) is basically the same as that of PC / PET-MD15, which can meet the requirements for use of radar covers in the temperature range of -30°C to 100°C.

[0053] Dielectric properties: The dielectric constant (2.8-2.9) and dielectric loss (0.006-0.007) of the present invention are both lower than those of PC / PET-MD15 (3.2 and 0.015), which is beneficial to improving the signal transmittance of millimeter-wave radar, enhancing the radar detection range, accuracy and reliability, and reducing signal transmission loss.

[0054] This invention successfully prepared a polypropylene composite material with low density, high rigidity, high heat resistance, low coefficient of linear expansion, good low-temperature toughness, and excellent dielectric properties by simultaneously introducing high-heat-resistant POE and high aspect ratio mica. Comparative results from Comparative Examples 1 and 2 show that the high aspect ratio mica mainly contributes to the improvement of room-temperature rigidity and dimensional stability, while the high-heat-resistant POE mainly contributes to the improvement of high-temperature rigidity and heat resistance. The synergistic effect of the two makes the overall performance of the composite material far exceed that of conventional polypropylene modification schemes, meeting the various performance requirements of radar covers for new energy vehicles and serving as a lightweight alternative to PC / PET-MD15.

[0055] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A polypropylene composite material for a lightweight radar cover, characterized by, It is prepared from the following components in parts by weight: 50.7-55.6 parts polypropylene, 10-20 parts high heat-resistant elastomer, 28-33 parts high aspect ratio mineral filler, 0.1-0.2 parts antioxidant, 0.1-0.2 parts lubricant, and 1-1.5 parts colorant; The melting temperature of the high heat-resistant elastomer is 117~120℃; The diameter-to-thickness ratio of the high diameter-to-thickness mineral filler is (80-120):

1.

2. The polypropylene composite for a lightweight radar cover plate according to claim 1, characterized by, The polypropylene is homopolymer polypropylene, copolymer polypropylene, or a mixture of homopolymer and copolymer polypropylene, and has a melt index of 3-100 g / 10 min at 230℃ / 2.16 kg.

3. The polypropylene composite for a lightweight radar cover panel according to claim 1, characterized by The high heat-resistant elastomer is an ethylene-octene block copolymer, selected from one or more of Dow Engage 8677, Engage 11567, Engage 11527 or POE 11547.

4. The polypropylene composite for a lightweight radar cover panel according to claim 1, characterized by, The high aspect ratio mineral filler is one or more of talc or mica.

5. The polypropylene composite for a lightweight radar cover panel according to claim 1, characterized by The antioxidant includes a primary antioxidant and a secondary antioxidant. The primary antioxidant is one of 1010, 1076, and 3114, and the secondary antioxidant is 168. The lubricant is one or more of calcium stearate, zinc stearate, stearate, erucamide, and oleamide.

6. A method for producing the polypropylene composite material for a lightweight radar cover panel according to any one of claims 1 to 5, characterized by, Includes the following steps: S1. Mix polypropylene, high heat-resistant elastomer, antioxidant, lubricant and colorant evenly according to the formula; S2. Using a side-feeding method, high aspect ratio mineral fillers are incorporated into the mixture in S1, and then melted, extruded, air-dried, and granulated by a twin-screw extruder to obtain the polypropylene composite material.

7. The production method according to claim 6, wherein In step S2, the extrusion temperatures of the twin-screw extruder are as follows: Zone 1 100±10℃, Zone 2 160±10℃, Zone 3 180±10℃, Zones 4 to 9 200±10℃, and the die head 210±10℃; the screw speed is 500-600 r / min, the length-to-diameter ratio is (48-58):1, the vacuum degree is -0.05~-0.1MPa, and the extruder head is equipped with a single-layer 80-120 mesh filter.

8. The preparation method according to claim 6, characterized in that, In step S1, high-speed stirring is used for mixing, with a stirring speed of 600-800 r / min and a mixing time of 5-8 min.

9. The application of a polypropylene composite material as described in any one of claims 1-5 or a polypropylene composite material prepared by the preparation method described in any one of claims 6-8 in the preparation of radar covers for new energy vehicles.

10. Use according to claim 9, characterized in that, The radar cover is a millimeter-wave radar protective cover.

Images