With the vigorous development of the automobile industry, various raw materials for manufacturing automobiles have also been rapidly developed and updated. More and more auto parts have begun to use modified plastics instead of metal parts. Plastics have been used in automobiles for nearly 50 years. History, the current use of modified plastics for automobiles has become an important indicator of the level of automotive design and manufacturing. The large number of applications of plastic parts has promoted the weight reduction and energy saving of automobiles and improved the aesthetic comfort of automobiles.
PP has a low density, high cost performance, excellent heat resistance, chemical corrosion resistance, rigidity, easy molding and recycling. It has been widely used in automobiles. Recently, there are automotive interiors and exteriors. The trend of unifying materials into PP series materials. Due to the long development cycle of high-performance base resin, huge investment, high technical requirements, and the need for sophisticated integrated advanced technology, the existing PP resin needs to be more extensive and more Effective, more economical, more practical modification.
Extensibility, mechanical strength and fracture resistance
Inorganic filler and elastomer toughening and reinforced modified PP is mainly 'three high'. It is a toughening elastomer and talcum powder from PP resin, EPDM and ethylene-octene copolymer (POE). A composite of inorganic fillers such as calcium carbonate, which is mainly used for injection molding of automobile bumpers, and the modified PP bumper has the advantages of low cost, light weight, easy coating, and recyclability.
The talc-filled modified PP material has high rigidity, low coefficient of thermal expansion and low shrinkage, and its chemical corrosion resistance is strong. Especially, the surface-treated talc filled with PP can effectively improve the impact properties of PP and improve the modulus of the material. And heat distortion temperature.
Glass fiber reinforced modified PP
The research and application of glass fiber reinforced modified PP materials, especially LGFPP materials, on automotive parts (such as the application of front-end modules, instrument panel skeletons, door modules and other typical components) is one of the research hotspots for many years.
LGFPP product refers to a three-dimensional structure formed by a glass fiber modified PP composite material with a length of 10~25mm through injection molding. 10~25mm long glass fiber reinforced polymer compared to ordinary 4~7mm short glass fiber reinforced polymer It has higher strength, stiffness, toughness, dimensional stability and low warpage. In addition, LGFPP material has better creep resistance than short glass fiber reinforced PP (GFPP), even if it is subjected to 100 °C. High temperatures do not produce significant creep.
Compared with metal materials and thermoset composites, LG-FPP has a low density and can reduce the quality of the same parts by 20% to 50%. LGFPP can provide designers with greater design flexibility and can form complex shapes and components. The ability to integrate automotive parts saves mold costs (generally the cost of long glass fiber reinforced polymer injection molds is about 20% of the cost of metal stamping dies), reducing energy consumption (long glass fiber reinforced polymer production energy is only steel 60%~ 80% of products, 35%~50% of aluminum products), simplify assembly process. New products of mineral fiber reinforced PP for automotive parts, high strength, low thermal expansion coefficient, high temperature resistance, good flame retardant performance, low Floating fiber, low warpage, low shrinkage and so on.
Foaming modified PP
PP foaming material is a low-density material made by increasing the melt strength of PP and increasing the expansion ratio. It has the advantages of light weight, heat resistance and high temperature resistance.
With the development of lightweight vehicles, the use of PP foaming materials has become an important way to reduce weight in automobiles. At present, it is increasingly used in automotive interiors, among which PP foaming materials are used in various automobiles. Compared with cars, 45%, trucks, construction machinery cars account for 20%, passenger cars, business vehicles account for 35%.
The PP foaming material for automobiles is mainly chemical micro-foaming material, because the apparent quality of ordinary micro-foamed PP products is not ideal, and it is only suitable for high-end vehicles that require surface covering, which not only increases the manufacturing cost but also limits the PP. The promotion and application of foaming materials; chemical microcellular foaming is based on a thermoplastic material, and the chemical foaming agent is a gas source. The gas is supercritical through a self-locking process, and the gas is diffused inside the cavity after being injected into the cavity. Under the action, the closed micropores with diameters from ten to several tens of micrometers are distributed in the middle of the product, and the ideal cell diameter should be <50μm ，但目前国内行业实际生产的微发泡PP的微泡孔直径约为80～350μm 。对于微孔发泡主要有注塑微发泡、吹塑微发泡和挤出微发泡等，注塑微发泡适用于各种汽车内外饰件，如车身门板、尾门、风道等;挤出微发泡适用于密封条、顶棚等;吹塑微发泡适用于汽车风管等。
The use of micro-foaming technology can reduce the quality of PP products by about 10% to 20%, which can achieve weight reduction of up to 50% compared with conventional materials, injection pressure is reduced by about 30% to 50%, and clamping force is reduced by about 20%. %, the cycle time is reduced by 10%~15%, and the energy saving of the car can be improved. The energy saving can be up to 30% compared with the traditional materials, and the warpage deformation of the product can be improved, and the design of the product and the mold can be more flexible.
In some parts, such as car air ducts, air ducts, it can also achieve heat insulation, noise reduction effect, and reduce the cost of the subsequent process. Radiation crosslinked PP high foam sheet with a density of 0.06g/cm3 has good mechanics. Performance, as a car roof, can reduce the quality of the car, and it can also be used in automotive interior parts, which is conducive to the weight of the car.
Scratch resistant PP
Polyolefins such as PP, rubber-modified PP, thermoplastic polyolefins and thermoplastic elastomers are more and more suitable for automotive and other fields than engineering plastics because of their recyclability, light weight and low cost. However, the scratch resistance of polyolefin materials is significantly worse, and this performance is the key performance of automotive interior applications such as dashboards, consoles and door panels, as well as automotive exterior applications, all-terrain vehicles (ATVs). One of the important properties, and the improved surface properties of polyolefins can be a good substitute for metal and engineering plastics, but also for coloring, so it is important to actively find solutions to improve the scratch resistance of polyolefin materials. By adding a coating Inorganic minerals and certain functional additives can improve the scratch resistance of polyolefins. For example, the addition of scratch-resistant agents can be used to prepare scratch-resistant automotive interior PP composites.
Recycling of modified PP for automobiles
As an environmentally friendly material, plastics are widely used in the automotive industry due to their strong plasticity, light weight and high recycling efficiency. Whether it is interior parts, exterior parts or functional structural parts, Plastics have been used in many places. The number of cars in China has reached 175 million. It is becoming more and more important to crush and recycle plastics used in automobiles. The recycling of automotive plastics will form a huge market and is a promising future. The field, academia and business have a lot of research and practice in this area.