US-12617932-B2 - Millimeter-wave radar housing material capable of being laser welded, and preparation method therefor

Abstract

A millimeter-wave radar housing material capable of being laser welded, and a preparation method therefor, which belong to the technical field of millimeter-wave radar housing manufacturing. The millimeter-wave radar housing material specifically comprises the following components in parts by weight: 50-90 parts of polypropylene, 10-50 parts of glass fiber, 0.2-0.8 part of a nucleating agent, 0.5-1 part of a compatibilizer, 0.1-0.5 part of a black colorant, 0.1-0.5 part of an antioxidant, and 0.1-0.8 part of a light stabilizer. The radar housing material disclosed by the present invention has the advantages of low dielectricity, being lightweight, high strength and high heat resistance, can transmit a near-infrared light beam, and has laser weldability.

Inventors

• Jun Lu
• Xiaojie Shen
• Lanjun LI
• Yong Zhao
• Yutong SHAO
• Bin Dong
• Shuyang Liu
• Tichao LU

Assignees

• NANJING JULONG SCIENCE & TECHNOLOGY CO., LTD.
• NANJING DONGJU CARBON FIBER COMPOSITE RESEARCH INSTITUTE CO., LTD.

Dates

Publication Date

20260505

Application Date

20210625

Priority Date

20201110

Claims (9)

1. 1 . A millimeter-wave radar housing material capable of being laser welded, comprising the following components in parts by weight: polypropylene 50-90 glass fiber 10-50 nucleating agent 0.2-0.8 compatibilizer 0.5-1 organic black colorant 0.1-0.5 antioxidant 0.1-0.5 light stabilizer 0.1-0.8. wherein the nucleating agent is a nano-scale acicular attapulgite; and wherein the organic black colorant is compounded by solvent red, solvent blue, solvent green, and solvent yellow in a weight ratio of (6-8):(3-5):(1-3):(0.5-1).
2. 2 . The millimeter-wave radar housing material capable of being laser welded of claim 1 , characterized in that, the polypropylene is one or more of a high flow homo-polypropylene or a co-polypropylene.
3. 3 . The millimeter-wave radar housing material capable of being laser welded of claim 1 , characterized in that, the glass fiber is one or more of an alkali-free glass fiber yarn treated with a silane-type impregnating agent.
4. 4 . The millimeter-wave radar housing material capable of being laser welded of claim 1 , characterized in that, the nano-scale acicular attapulgite has an aspect ratio of 30-50 and an average particle size of 5-8 micrometers.
5. 5 . The millimeter-wave radar housing material capable of being laser welded of claim 1 , characterized in that, the compatibilizer is a graft polymer of maleic anhydride and polyolefin, and the maleic anhydride graft ratio is 1.0%-2.5%.
6. 6 . The millimeter-wave radar housing material capable of being laser welded of claim 1 , characterized in that, the solvent red is E2G; the solvent blue is RR; the solvent green is 5B; the solvent yellow is Yellow G.
7. 7 . The millimeter-wave radar housing material capable of being laser welded of claim 1 , characterized in that, the antioxidant is one or more of hindered phenols, phosphite esters and thioester.
8. 8 . The millimeter-wave radar housing material capable of being laser welded of claim 1 , characterized in that, the light stabilizer is one or more hindered amines, benzotriazoles, and benzophenones.
9. 9 . The preparation method for a millimeter-wave radar housing material capable of being laser welded of claim 1 , comprising the steps of: adding polypropylene, a compatibilizer, an antioxidant, an organic black colorant, a nucleating agent and a light stabilizer into a mixer in parts by weight, thoroughly and homogeneously mixing the same to obtain a premix; adding the premix into a twin-screw extruder; extruding the resulting resin melt into an impregnation die connected to a head of the twin-screw extruder; then passing the continuous glass fiber through the impregnation die, sufficiently impregnating the continuous glass fiber with the melt; finally cooling, drawing and pelletizing the resultant material to obtain a millimeter-wave radar housing material capable of being laser welded, wherein the nucleating agent is a nano-scale acicular attapulgite.

Description

FIELD OF THE PRESENT DISCLOSURE The present invention relates to the field of millimeter-wave radar housing materials and, in particular, to a 77 GHz millimeter-wave radar housing material capable of being laser welded. BACKGROUND OF THE PRESENT DISCLOSURE Millimeter-wave radar is a radar that is operated within the millimeter-wave band, usually in the 30-300 GHz frequency band. The automotive millimeter-wave radars mainly include 24 GHz narrowband radar (24.00-24.25 GHz), 24 GHz ultra-wideband radar (24.25-24.65 GHz), 77 GHz radar (76-77 GHz), and 79 GHz radar (77-81 GHz). Compared with the 24 GHz radar, the 77 GHz radar is smaller in size and has better detection accuracy, and the requirements for radar housing materials are in a tendency for lower dielectric constant, lower dielectric loss, and lightweight. The radar housing material must meet the requirements of dielectric properties, mechanical properties, process properties, and weight. The dielectric properties of materials include dielectric constant and dielectric loss. If the dielectric constant is large, the reflectivity of the electromagnetic wave at the interface between the air and the radar housing will be large, which will increase the mirror lobe level and reduce the transmission efficiency. If the dielectric loss is large, energy loss, due to conversion of the electromagnetic wave energy into heat when penetrating the radar housing, is higher. Therefore, it requires both the dielectric constant and dielectric loss of the radar housing material to be as low as possible to achieve the purpose of maximum transmission and minimum reflection. The low dielectric constant material imparts a broadband response to the radar housing, allowing larger housing thickness tolerances, thereby reducing manufacturing costs. Generally, the millimeter-wave radar housing material adopts fiber-reinforced thermoplastic composite materials, such as polyphenylene sulfide (PPS), polybutyene terephthalate (PBT), and polyimide (PI). A PPS capable of balancing various properties has been developed by Polyplastics, Japan. A polyimide (PI) material suitable for millimeter-wave radar has been developed by Toray, Japan. A radar wave penetrable material based on a reinforced PBT modified by glass fiber has been developed by SABIC. These materials have the advantages of high strength, high-temperature resistance, and chemical resistance, but the problems of high density and high cost limit the broad application of these materials in the field of millimeter-wave radar. In addition, PBT and PI materials contain polar groups, and their dielectric constants are generally higher than 3. After glass fiber reinforcement, the dielectric constant is higher than 3.5, which limits the use in millimeter-wave radar. Glass fiber reinforced polypropylene has a relatively low dielectric constant and low cost. In recent years, glass fiber reinforced polypropylene is becoming more and more popular for radar housing material. Patent No. CN110527188A discloses a high-wave-transmissivity polypropylene composition and a preparation method thereof. In the range of 22 GHz-80 GHz millimeter-wave, the frequency loss of the material is less than 3%. The dielectric constant is about 2.2 under the 1 MHz test condition. The material has a relatively high wave-penetration performance and a relatively low dielectric constant. However, its low strength and poor heat resistance make it inappropriate for radar housing applications. Generally, the radar housing is fixed on the mounting surface by means of screws. However, this installation has many disadvantages, such as easy loosening, detachment, and poor sealing performance, and cannot protect the radar device well. Compared with screw connection, laser welding plastic has the advantages of reliable connection, good sealing, easy processing, and water impermeability, which can ensure millimeter-wave transmission performance. The principle of plastic laser welding is that two parts of plastic to be welded are pressed together by pressure, then a near-infrared laser beam passes through a laser-transmitting materials at an upper layer, and is absorbed by the laser-absorbing materials at a lower layer to melt the plastic contact surface, thereby bonding the thermoplastic sheet, film or molded parts together. As a modern welding technology, laser welding has many advantages, such as large melting depth, high speed, small deformation, low requirements for the welding environment, high power density, not affected by the magnetic field, without limitation to conductive materials, no vacuum operation conditions and no X-ray generated during the welding process. It is very suitable for the welding of miniature parts and poorly accessible parts and is widely used in the field of high precision manufacturing. In view of the structural characteristics of polyolefin, only laser-absorbing carbon black is an ideal black pigment for polyolefin, and laser transmission weldi