Polypropylene material and preparation method thereof, structural part and making method thereof

Abstract

The invention relates to a polypropylene material and a preparation method thereof, a structural part and a making method thereof. The polypropylene material is suitable for vibration friction welding, and is formed by adding a specific ethylene-propylene random copolymer and a nucleating agent into linear homo-polypropylene, because of the introduction of the random copolymer, in a vibration melting process, the polypropylene material can be quickly molten only by a small welding amplitude, and the excessive orientation of a polypropylene molecular chain in the vibration direction is reduced,so that the mechanical properties of the polypropylene material in a direction perpendicular to the vibration direction are improved, and the strength of a welded seam is enhanced. In addition, the polypropylene material can be rapidly molten in the vibration melting process to reach a set welding depth quickly, thus effectively reducing the welding time. Due to the adding of the nucleating agent, the polypropylene melt has higher crystal nucleus generation rate in the cooling process after vibration melting to form more crystal nucleuses, thereby enhancing the crystallinity of the material at a welded seam, and ensuring the strength of the welded seam.

Description

technical field [0001] The invention relates to the technical field of vibration friction welding, in particular to a polypropylene material and a preparation method thereof, a structural part and a preparation method thereof. Background technique [0002] Vibration friction welding is a kind of thermal welding with high efficiency and low energy consumption. There is no need to add solvents, adhesives or other auxiliary products during welding, and the welding materials have no surface damage. The operation is simple and it is easy to realize mechanization and automation. [0003] For some polypropylene special-shaped structural parts, such as automotive interior parts, it is difficult to be molded through one-time injection molding. It can be designed into relatively simple multiple parts, and then assembled by vibration friction welding. [0004] The characteristic of polypropylene material is an important factor affecting the efficiency of vibration friction welding. Th...

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Problems solved by technology

[0005] Polypropylene is a semi-crystalline polymer, and welding requires high amplitude, high welding pressure, and long welding time to melt the welding surface to achieve welding, but this will lead to problems such as reduced weld strength and strength retention

Specifically, when the amplitude is high, the flow rate of the molten material is faster, resulting in an increase in molecular chain orientation, resulting in a large amount of flash and a decrease in weld strength; , reduce the strength of the weld; longer welding time, it is easy to cause local overheating, leakage, resulting in a decrease in the strength of the weld, and the strength retention rate of the weld is extremely low

[0006] The existing vibration friction welding method mainly improves the welding performance by adjusting the external conditions such as the amplitude, frequency, power, welding depth, welding pressure, and adding energy-conducting ribs. The change of these conditions improves the welding efficiency. Pressure to shorten welding time to improve welding efficiency will also lead to weakening of weld strength

In addition, polypropylene is filled with talcum powder, glass fiber and other reinforcing fillers to improve weld strength and strength retention. However, this will increase the density of the material, which is not conducive to the lightweight of the final product. There is also a way to add carbon fiber to reduce the density, but the material cost will be greatly increased

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