The main function of engineering plastics used in automobiles is to make automobiles lightweight, so as to achieve the purpose of fuel saving and high speed. Developed countries regard the amount of plastics used in automobiles as an important index to measure the level of automobile design and manufacturing. Germany is the country with the largest amount of plastics for automobiles in the world, accounting for 65,438+05% of the total materials. In recent years, China automobile industry has developed rapidly. At present, the annual output of automobiles exceeds 4 million. According to the forecast of foreign plastic consumption, the annual consumption of modified plastics in automobile industry is over 500,000 tons, of which engineering plastics account for a large proportion. The performance characteristics of the five major engineering plastics are different, and their applications in automobiles are also biased.
I. Nylon
Nylon is mainly used in automobile engines and engine peripheral parts. The main varieties are GFPA6, GFPA66, enhanced flame retardant PA6 and other products. Application of (1) in the peripheral parts of automobile engine Because the peripheral parts of the engine are mainly heating and vibrating parts, the materials used in the parts are mostly glass fiber reinforced nylon. This is because nylon has good comprehensive properties. The main properties of glass fiber modified nylon, such as strength, product accuracy and dimensional stability, have been greatly improved. In addition, there are many kinds of nylon, which are easy to recycle and relatively cheap. These factors make nylon an ideal choice for engine peripheral components. Intake manifold is the most typical application of modified nylon in automobiles. 1990, BMW Germany first applied the intake manifold made of glass fiber reinforced nylon to the six-cylinder engine. Later, Ford cooperated with DuPont to apply the intake manifold made of glass fiber reinforced PA66 to V6 engine. Later, the world's major automobile companies followed suit, and modified nylon intake manifold was widely used. (2) Application in automobile engine parts. Modified nylon is generally the first choice for engine hood, engine decorative hood, cylinder head cover and other parts. Compared with metal materials, the weight of cylinder head cover is reduced by 50% and the cost is reduced by 30%. In addition to engine parts, reinforced nylon can also be used for other stressed parts of automobiles, such as oil filters, wipers and radiator grilles.
Second, polyester
In the field of automobile manufacturing, PBT is widely used to produce bumpers, carburetor assemblies, mudguards, spoilers, spark plug terminal boards, oil supply system parts, instrument panels, automobile igniters, throttles, clutch pedals and so on. The competition between PBT and PA, PC and POM in automobile manufacturing industry is fierce, PA is easy to absorb water, and the heat resistance and drug resistance of PC are not as good as PBT. PBT will gradually replace PA because of its better water absorption resistance than PA. In the case of high relative humidity and very humid, modified PBT can often be used because humidity is easy to cause plastic reduction and electrical node corrosion. At 80℃ and 90% relative humidity, PBT can still be used normally with good effect.
PBT/PC alloy of GE Company, trade name Xenoy 173 1, is the most widely used alloy in cars. It has good heat resistance, stress cracking resistance, excellent wear resistance, chemical corrosion resistance, high low-temperature impact strength, easy processing and good smoothness, and is mainly used for bumpers, floors, panels and motorcycle guards of high-end cars.
Third, polyformaldehyde.
The biggest potential market of polyoxymethylene in automobile industry. POM has the advantages of light weight, simple processing and molding, low production cost and material properties similar to those of metal. The wear resistance coefficient of modified polyoxymethylene is very low and its rigidity is very strong. It is very suitable for manufacturing automobile pumps, carburetor parts, oil pipelines, power valves, universal joint bearings, motor gears, cranks, handles, instrument panels, automobile window lifting devices, electrical switches, seat belt buckles, etc. Manufacturing wear-resistant parts such as shaft sleeve, gear and slider is the strength of modified POM. These parts have little wear on metal, which reduces the amount of lubricating oil and improves the service life of parts. Therefore, it can widely replace copper, zinc and other metals to produce bearings, gears, pull rods and so on. The automobile parts produced by POM are light in weight, low in noise, simple in molding and assembly, and widely used in automobile manufacturing.
Four. polycarbonate
Because of its high mechanical properties and good appearance, modified PC is mainly used in exterior and interior parts of automobiles, among which PC/ABS alloy and PC/PBT alloy are the most widely used.
(1) PC/ABS alloy is the most suitable material for automobile interior decoration. This is because PC/ABS alloy has excellent heat resistance, impact resistance and rigidity, as well as good processing fluidity. It is also an ideal material for manufacturing automobile dashboard. The thermal deformation temperature of PC/ABS alloy is 1 10℃ ~ 135℃, which can completely meet the heating requirements of outdoor parking in tropical countries at noon in hot summer. PC/ABS alloy has good paintability and adhesion to covering film, so the dashboard made of PC/ABS alloy can be directly sprayed with soft topcoat or PVC film without surface pretreatment.
PC/ABS alloy is also used to manufacture automobile parts, such as peripheral parts of automobile dashboard, anti-freezing plate, door handle, deflector, bracket, steering column sheath, decorative plate, air conditioning system accessories and so on.
(2) PC/PBT alloy and PC/PET alloy used for automobile exterior decoration have high heat resistance and impact resistance of PC, chemical resistance, wear resistance and moldability of PBT and PET, and are ideal materials for manufacturing automobile exterior decoration. The PC/PBT automobile bumper can withstand the low temperature impact below -30℃, and the bumper is ductile fracture without fragments. PC/PBT alloy and PC/PET alloy toughened by elastomer are more suitable for making automobile body panels, automobile side guards, fenders and automobile door frames. Injection molded external parts of high heat-resistant PC/PBT alloy and PC/PET alloy need not be painted. PC/PET alloy can be used to manufacture automobile exhaust port and license plate cover.
PC/ABS alloy can also be used to make automobile exterior decoration parts, such as automobile wheel cover, reflector shell, tail lampshade and so on. PC/ABS has good formability and can be used to process large automobile parts, such as automobile fenders.
Verb (abbreviation of verb) polyphenylene ether
Modified PPO is mainly used as a component in automobile which requires high heat resistance, flame retardancy, electrical performance, impact performance, dimensional stability and mechanical strength. For example, PPO/PS alloy is suitable for wet, loaded, high electrical insulation requirements and good dimensional stability, and is suitable for manufacturing automobile wheel covers, headlight glass troughs, taillight housings and other automobile electrical components such as junction boxes, fuse boxes and circuit breaker housings.
PPO/PA alloy has excellent mechanical properties, dimensional stability, oil resistance, electrical insulation and impact resistance. Can be used for manufacturing automobile exterior decoration parts, such as large baffles, cushion pads, rear spoilers and the like. The future application direction of PPO/PA alloy is range hoods with high glass transition temperature requirements.
PPO/PBT alloy has high thermal deformation temperature and low sensitivity to moisture, so it is an ideal material for manufacturing automobile exterior panels.
The development direction of automobile industry is high-grade, miniaturization, lightweight and diversification, and the research of replacing steel with plastic in automobile application has also become very active. At present, domestic automobile plastics account for 7% of the total materials on average, and the proportion in Germany is15%; We need to increase R&D work to realize the structural design of parts, the selection of plastic materials and the synchronous development of the industry.