High-welding-strength polypropylene composition as well as preparation method and application thereof

Abstract

The invention relates to a high-welding-strength polypropylene composition as well as a preparation method and application thereof. The high-welding-strength polypropylene composition comprises an ethylene-propylene block copolymer, an ethylene-propylene random copolymer, low-density polyethylene, cyclic polyolefin, an antioxidant and a lubricant. By adding the low-density polyethylene and the ethylene-propylene random copolymer, a synergistic effect is achieved for improving the melt strength and the welding strength of the product, a thin-wall extrusion pipe can be formed, and the product isexcellent in welding strength and good in sealing performance and has a good application prospect.

Description

technical field [0001] The invention belongs to the field of modified plastics, in particular to a polypropylene composition with high welding strength and its preparation method and application. Background technique [0002] As one of the five general-purpose plastics, polypropylene is widely used in household appliances, automobiles, daily necessities, chemical building materials and other fields. The main molding methods of polypropylene materials are injection molding, extrusion, and blow molding. Due to the excellent temperature resistance and chemical stability of polypropylene materials, polypropylene materials are more and more widely used in the field of extrusion molding. [0003] However, since the structure of polypropylene is usually a linear molecular chain, and there is no branched chain in the molecular chain, the melt strength of itself is low, and melt fracture is prone to occur during the thin-wall extrusion molding process. Forming thin-wall corrugated pi...

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Problems solved by technology

[0003] However, since the structure of polypropylene is usually a linear molecular chain, and there is no branched chain in the molecular chain, the melt strength of itself is low, and melt fracture is prone to occur during the thin-wall extrusion molding process. Forming thin-wall corrugated pipes or sheets It is difficult to extrude products such as materials

Chinese patent CN102477202B discloses a thin-walled corrugated pipe modified by waste polypropylene. By adding peroxide masterbatches and small molecule monomer masterbatches, the small molecule monomers undergo grafting reactions under the action of peroxides during the molding process to produce branched chains. Improve the melt strength and improve the compatibility between polar impurity resins. Although this technical solution can provide the melt strength of the material and form thin-walled extruded products, the addition of peroxide will inevitably have an adverse effect on environmental protection and safety. And there are problems of difficult control and monomer residue in reactive extrusion

[0004] In addition, extruded products usually need to be further welded and formed. Since polypropylene is a crystalline polymer, the melt strength decreases during welding and melting, and molecular chain orientation problems lead to a decrease in welding strength, resulting in insufficient structural strength and tightness of the product.

Chinese patent CN110669287A discloses a polypropylene material suitable for vibration friction welding. By adding ethylene-propylene random copolymer and nucleating agent, the molecular chain orientation is reduced and the matrix strength is increased, thereby achieving high welding strength. However, random copolymerization The addition of the nucleating agent did not fundamentally change the orientation of the polypropylene molecular chain, and the addition of the nucleating agent increased the crystallinity to a limited extent for the strength of the matrix

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