Performance Analysis and Application of Polypropylene Materials for Vehicles

Plastic is one of the commonly used non-metallic materials for passenger cars. In mid-size cars, the amount of plastics has accounted for 12% to 15% of the total vehicle quality. Among automotive plastics, polypropylene is one of the fastest growing plastics with the highest application rate and the highest frequency of use. Taking the data of a mainstream intermediate car dismantling manual as an example, polypropylene materials account for about 29% of the frequency of plastics used in the whole vehicle, and polypropylene materials account for about 48% of the plastics consumption of the whole vehicle. Therefore, the performance analysis of polypropylene materials and typical application case studies have practical significance for the development of raw materials for automotive parts.

Polypropylene (PP) resin is a non-polar crystalline plastic obtained by polymerizing propylene monomer. PP has the advantages of low price, low density, easy processing and recycling; but PP has the disadvantages of large molding shrinkage, high temperature brittleness and easy aging. Therefore, physical or chemical modification technology is usually used, adding talc filler, glass fiber and other reinforcing materials, anti-light/thermal oxygen aging agent and other additives to improve the comprehensive performance of polypropylene materials to meet the performance requirements of automotive parts.

(1) Application analysis of PP EPDM-TD materials in bumper exterior parts

A lot of research has been carried out on the modified polypropylene material of the front and rear bumper bodies. The modified PP bumper has the advantages of low cost, light weight, easy coating and recyclability. At present, the selection of Beiqi Futian passenger car bumper body mainly uses PP EPDM-TD10 or PP EPDMTD20 modified polypropylene material. By adding 10-20 parts of talc powder, the material shrinkage rate and component size can be ensured; the EPDM or POE elastomer is toughened, and the component has good low temperature impact resistance.

As the focus of lightweight vehicles has increased, lightweight design has placed a number of new demands on the application of plastic materials. The bumper can be reduced in weight by designing the thickness of the wall, so that the requirements for the melt index are getting higher and higher, and the requirements for material strength are also improved. With the reduction of cost pressure and increasingly strict environmental protection requirements, the spray-free bumper comes into being. Higher requirements are placed on the surface quality of modified polypropylene materials, such as scratch resistance.

(2) Analysis of the application of modified PP on interior parts

The large parts made of modified PP materials for automotive interior parts include instrument panels, door panels, pillar trims and other components. A large amount of research has been conducted in the industry for modified polypropylene materials for components such as instrument panel bodies and lower guard plates, door panel bodies, and pillar trim panels. In the development of new models, the selection of components is more in line with the comprehensive factors such as vehicle positioning, cost, regulations and performance. For example, A-class vehicles (entry-level passenger vehicles) and B-class vehicles (intermediate passenger vehicles) have certain differences in the selection of parts and materials due to target customers and vehicle cost pressures and light weight requirements. Class A passenger cars pay attention to the economics of interior parts. For example, hard instrument panels, hard door panels, and hard pillars are generally used, and the surface is generally not covered with fabric or leather.

(3) Application analysis of PP-LGF on the front-end module

The research and application of PP-LGF (long glass fiber reinforced polypropylene) material is one of the hotspots in recent years. In PP-LGF materials, glass fibers generally have a length of 15 mm to 30 mm, forming a three-dimensional cross structure. The structure determines the performance, so PP-LGF has higher strength, rigidity and toughness than ordinary 4-7mm short glass fiber materials. For the front end module of the car, the PP-LGF30 material can be used to combine the front end parts of the radiator, the horn, the condenser, the bracket and the like into a whole; compared with the metal parts, the corrosion resistance, the density is small, the weight is light, and the weight loss is about 30%; Compared to fiberglass nylon, there is a clear cost advantage.