The main plastic material of the car (3)
Third, special plastics
Glass fiber reinforced plastic is based on the original pure plastic, adding glass fiber and other additives to improve the use of the material. In general, most of the glass fiber reinforced materials are used in structural parts of the product, which is a structural engineering material; such as: PP, ABS, PA66, PA6, PC, POM.
①After the glass fiber is reinforced, the glass fiber is a high temperature resistant material, so the heat resistant temperature of the reinforced plastic is much higher than before the glass fiber is added, especially the nylon plastic;
②Restricting the mutual movement between the polymer chains of the plastic, so the shrinkage rate of the reinforced plastic is greatly reduced, and the rigidity is also greatly improved;
③Reinforced plastic will not stress cracking, and the impact resistance of plastic will be improved a lot;
④Glass fiber is a high-strength material, which also greatly increases the strength of the plastic (tensile strength, compressive strength, bending strength are improved a lot);
⑤Due to the addition of glass fiber and other additives, the flammability of reinforced plastics is much reduced, and most materials cannot be ignited.
①Is transparent before adding glass fiber, and it will become opaque;
②The toughness of the plastic is reduced, and the brittleness is increased;
③The melt viscosity of all materials increases, the fluidity deteriorates, and the injection pressure is much higher than that without glass fiber;
④Poor fluidity, for normal injection molding, the injection temperature of all reinforced plastics is 10 ° C - 30 ° C higher than before adding glass fiber;
⑤The absorbing property of the reinforced plastic is greatly enhanced. The original pure plastic will not become absorbent when it absorbs water. Therefore, it must be dried during injection molding;
⑥In the injection molding process, the glass fiber can enter the surface of the plastic product, making the surface of the product become rough and spotted (in order to achieve a higher surface quality, it is better to use a mold temperature machine to heat the mold during injection molding, so that the plastic polymer enters The surface of the product, but can not achieve the appearance quality of pure plastic);
⑦Glass fiber is a material with high hardness. It is a highly corrosive gas after high temperature volatilization. It wears and corrodes the screw and injection mold of the injection molding machine. Therefore, it produces molds and injection molding machines using such materials. Attention should be paid to the surface anti-corrosion treatment and surface hardness treatment of the equipment.
The shrinkage rate of commonly used glass fiber:
PP+glass fiber: 0.2-0.8%
ABS+glass fiber: 0.1-0.2%
PA66+ glass fiber: 0.5%
PA6+ glass fiber: 0.4%
POM+glass fiber: 0.9-1.2%
Representative of glass fiber reinforced materials, glass fiber reinforced plastic / composite materials in the automotive industry:
Body parts: including body shell, hood hard roof, sunroof, door, radiator grille, headlight reflector, front and rear bumpers, etc. This is the main direction of application of FRP/composite materials in automobiles. It is mainly aimed at adapting to the needs of streamlined design and high quality requirements of the body. The current development and application potential is huge. The material of this part is mainly made of glass fiber reinforced thermosetting plastic. Typical molding processes include: SMC/BMC, RTM and hand paste/jetting.
Structural parts: including front end brackets, bumper frames, seat frames, floors, etc., the purpose is to improve the design freedom, versatility and integrity of the parts. Mainly use high-strength SMC, GMT, LFT and other materials.
Functional parts: Its main features are required to withstand high temperature and oil corrosion, mainly based on engine and engine peripheral components. Such as: engine valve cover, intake manifold, oil sump, air filter cover, gear chamber cover, air hood, intake pipe guard, fan blade, fan air guide, heater cover, water tank parts, Outlet housing, water pump turbine, engine insulation board, etc. The main process materials are: SMC/BMC, RTM, GMT and glass fiber reinforced nylon.
Although many types of plastics are used in a certain vehicle, according to relevant data, three of them account for 66% of the total high-performance plastics in automobiles: polypropylene (32%), polyurethane (17%) and PVC (16). %). Therefore, the improved research and production work of high-performance plastic parts is basically carried out around these three plastics.