Polypropylene composition and preparation method thereof

The invention discloses a polypropylene composition, which comprises the following components by weight: 90-100 parts of copolymerized polypropylene; 1-10 parts of branched polyethylene; 0.1-0.5 parts of nucleating agent; Among them, the molecular weight of copolymerized polypropylene is 25000-30000, the range of molecular weight distribution (MWD) is 2.5-3.0, the isotacticity range of polypropylene is 90% - 95%, aPP accounts for 0.5% - 1.5% of the total weight of copolymerized polypropylene, and EP accounts for 0.5% - 5.0% of the total weight of copolymerized polypropylene. The polypropylene composition of the invention takes polypropylene as the main body of the resin matrix. Through the design of the microstructure of polypropylene chain segment and the selection of branched polyethylene with specific chain segment structure, the interface energy between polypropylene and polyethylene is effectively reduced, the interface bonding force between the two resins is improved, the chain segment and lattice defects are reduced, and combined with high-efficiency nucleating agent, it has the advantages of yellowing resistance and chemical resistance.