What is the function of modified plastics in auto parts?

2020-01-14 09:52:24

Modified plastics are based on general plastics and engineering plastics. Through adding modifiers, filling, blending, strengthening and other methods, they improve the flame retardancy, strength, impact resistance and toughness of plastic products. Modified plastics are widely used in automobile industry because of their unique properties that other materials do not possess. With the increasing requirements of automobile lightweight, energy saving and environmental protection, the amount of automobile modified plastics is increasing year by year. In October 2016, China Society of automotive engineering released the energy saving and new energy vehicle technology roadmap. The roadmap points out that by 2020, 2025 and 2030, the vehicle mass needs to be reduced by 10%, 20% and 35% respectively compared with 2015. Modified plastics for automobile mainly include polypropylene, polyurethane, ABS materials, HDPE, polycarbonate, nylon, etc. According to the data, China's total plastic production increased from nearly 18 million tons in 2004 to nearly 80 million tons in 2016, and the modification rate increased from 8% to 19%. However, compared with 40% of the world's modified plastics used in the automobile industry, only about 10% in China. In late November 2016, it is expected that in the next few years, the automotive industry will become a fast growing area of China's modified plastic consumption. It is estimated that China's annual output of automobiles will reach 30 million in 2021. According to the conservative usage of each 300 kg automobile modified plastic, the compound annual growth rate of automobile modified plastic industry will exceed 26% in the next five years. In the next few years, the upgrading of polyolefin and modified plastics products in petrochemical and coal chemical industry needs to focus on the automotive plastics market.

The lightweight of the body is very important for the automobile. The plastic material can be used to form the body covering at one time, without subsequent treatment, which can reduce the cost. Compared with metal panel, NVH, stable quality, precise size and smooth surface are smaller. For example, Ford uses SMC to make front guard plate, top cover plate and engine hood, which can achieve 35% weight reduction. For example, xenoypcp / BT is used in the new smart model of DaimlerChrysler company to make the car body panel, which has good dimensional stability, UV linear resistance, corrosion resistance, toughness, impact resistance and other properties. In the automobile chassis, there is a big problem of plastic because of the large load. Therefore, at present, modified plastics are mainly used in the wear-resistant parts of transmission suspension system and steering brake system, such as modified PBT, modified POM and other materials.

In the inner guard board, taking 2443abs applied by Audi TT as an example, the flow performance is good, the quality can be guaranteed in the injection molding process, and the good functionality and aesthetics can be achieved when processing the convective linear door guard board. Generally, modified PP and ABS are used to make skeleton, PP foam, TPU and knitted polyester are used as buffer layer, which have good rigidity and hand feeling. It can also use rimpu as buffer layer and knitted polyester as surface layer, with good handle and rigidity. In some models of GM and Chevrolet, the frame and panel are made of SMC material, or made of 50% PP and 50% natural fiber by hot pressing, which effectively reduces the cost. In automobile dashboard, soft and hard are mainly used. In the modified PP for instrument panel, the non polar filler and PP rubber toughener are the main components, which have the advantages of good performance and low price. PVC / ABS is used as the skin material of instrument panel. Among them, PVC has good electrical properties, flame retardancy and chemical stability, ABS has good molding processability and mechanical properties, and the combination of the two can play a better role. This instrument panel does not need to be treated and can be coated directly. Based on the convenience of recycling, the instrument panel is made up of PP foam material and modified PP skeleton TPO.

One of the main plastic parts of the automobile is the bumper. The use of modified plastic can ensure the functionality while increasing the aesthetics. At the same time, the performance of the modified plastic is better than that of the metal parts in the slight scratch and collision. At present, most automobile bumpers are made of polymer materials, such as PU foam, PP foam and other materials to make the middle layer, metal, wood and other materials to make the skeleton, PCP / BT, PC / ABS, PP and other panels. In order to improve the environmental protection, foam PP can be used to make the middle layer, glass fiber reinforced PP can be used to make the framework, and TPO can be used to make the automobile bumper panel. In terms of fuel tank, modified plastics also play an important role. Materials such as collective value, adhesive, PA can be mixed according to a certain proportion, and then blow molded. In addition, the fuel tank can also be made of uhmwhdpe, copolymerized PA, EVOH resin, hmwhdpe and other materials. It is difficult to make the intake manifold of automobile engine with complex shape by using one-time injection molding technology. For this, when producing aim, two to three aim parts can be respectively molded, and then vibration welding can be carried out. For example, in some models of Chrysler and Cadillac engines, the glass fiber reinforced PA is applied in the manufacturing of aim. Around the engine, the operating temperature usually exceeds 200 ℃, so the high modulus and high strength should be maintained. In some cold areas, the temperature should be zero to ten degrees. Therefore, PA66 material can be used to ensure the performance of plastic parts. The clutch actuating system needs to operate at high temperature and bear the influence of pressure oil lubricant.

In the past, the master and slave cylinders were usually made of metal parts. With the application of modified plastics, the clutch actuating system made of plastics gradually appeared, in which the main component is 50% long fiber reinforced black nylon LFRT. Because 50% long fiber is added, the coefficient of thermal expansion of metal parts can be achieved, in which the fiber is evenly distributed, with modulus higher than that of aluminum alloy, and with stability