High fused mass strength polypropylene containing long branched chain structure and preparing method thereof

Abstract

The invention relates to a high fused mass strength polypropylene contained long-chain branch and the preparation method thereof. The high fused mass strength polypropylene resin is prepared by polypropylene grafted object, amine or alcohols compound as well as antioxidant and heat stabilizer, etc. The invention adopts a melting and continuously extrusion method with a reaction-type double screw extruder to prepare the high fused mass strength polypropylene, and uses supercritical carbon dioxide to assist the extrusion, which can lower the extrusion temperature, reduce the degradation of polymer and meanwhile greatly strengthen the pervasion of molecule, so as to further promote the reaction. In the reaction process, as chain extender, amine and alcohols compound react with special functional group of polypropylene grafted object, link linearity polypropylene molecular chain, consequently produce novel polypropylene that each grafted point includes two long-chain branch structures and of which the melt flow rate is adjustable. The novel polypropylene is characterized by non-gelatin and strain hardening. The product shows great advantages over a plurality of aspects like color, mechanical property and workability, therefore, the product is suitable for application areas of blowing, thermo-forming, blown film, extrusion and coating, etc.

Description

technical field [0001] The invention relates to a high-melt-strength polypropylene containing a long-chain branch structure and a preparation method thereof. Background technique [0002] The polypropylene (PP) industry is developing rapidly, but currently Ziegler-Natta and metallocene catalysts are mainly used to catalyze the production of high-isotactic PP (iPP), which generally cannot produce secondary active centers and only has a linear chain structure, resulting in a narrow molecular weight distribution. Disadvantages such as low melt strength and poor sag resistance. Moreover, PP has no strain hardening effect in the molten state, thus greatly limiting the application range of PP. In addition, PP is also a partially crystalline polymer, the softening point is very close to the melting point, and the melt strength drops rapidly after exceeding the melting point, resulting in uneven wall thickness of the container when thermoforming is used, and edge curling and shrink...

AI Technical Summary

Problems solved by technology

However, because it is extremely difficult to achieve uniform dispersion at the molecular level only by simple blending, the mechanical properties of the product are not ideal

[0005] Himont's patent CN86100791 uses electron cathode rays to irradiate straight-chain PP to produce long-chain branching and produce HMSPP with higher weight-average molecular weight and higher degree of branching. However, since PP is a semi-crystalline polymer, the amorphous part Grafting has occurred, and the crystallization area is more difficult. Although some measures can be taken, such as reducing crystallinity, etc., it is still easy to form a large amount of uneven gel, so there is a problem of product performance stability

Chinese patents CN1986589A and CN1432596A disclose the method of using acrylate melt-grafted polypropylene to improve the melt strength, but the traditional melt reaction extrusion has serious degradation of the main chain of polypropylene due to high temperature, which affects the overall performance of the product

[0006] However, solution grafting requires a large amount of solvent in the production process, which not only wastes resources, but more importantly, the solvent is harmful to the surrounding environment and individuals.

Melt grafting has the problem that polypropylene is easy to oxidize and degrade due to the operation at high temperature.