Preparation method of high melt strength polypropylene by solid phase reaction

Abstract

The invention relates to a preparation method of high melt strength polypropylene by solid phase reaction. The purpose of the invention is to solve the problems that universal polypropylene is low instrength and is hard to be applied to the fields such as foaming, hollow molding. A formula of the high melt strength polypropylene comprises the following materials in parts by weight: 100 parts of powdery or granular polypropylene, 1 to 4 parts of grafted monomer, 0.2 to 4 parts of an antioxidant, the preparation method comprises the following steps: weighing and uniformly mixingpowdery or granular polypropylene, grafted monomer and the antioxidant, enabling the three to react for 5 to 40 mins at the temperature of 120 to 130 DEG C in air, after reaction, adding 0.1 to 0.4 parts by weight ofthe antioxidant and uniformly stirring (used for stabilization of subsequent processing and forming), thus obtaining high melt strength polypropylene. The invention provides a method for preparing high melt strength polypropylene with simple process, flexible operation, low cost, good environmental protection, good color and luster with large scale industrial implementation prospect, branched structure and a small amount of cross-linking structure.

Description

technical field [0001] The invention relates to a method for preparing high-melt-strength polypropylene by solid-phase thermal oxygen initiation, in particular to a method for preparing high-melt-strength polypropylene using a thermal-oxygen solid-phase grafting method without an initiator, and belongs to the field of plastic materials. Background technique [0002] Polypropylene (PP) has excellent comprehensive performance and good environmental degradation, so it has strong competitiveness and prospects in the application field of foamed plastics. However, polypropylene (PP) of semi-crystalline plastics is difficult to foam. It does not melt below the melting point, and the melt strength decreases rapidly above the melting point, and the bubbles cannot be wrapped, and problems such as cell collapse and merging occur, making it difficult to obtain good foamed products. [0003] To solve the problem of difficult foaming of polypropylene, it is necessary to increase the melt ...

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Problems solved by technology

[0006] The method provided by the above-mentioned patent has the following problems. It is difficult for the initiator to distribute uniformly in the material. Therefore, it will lead to uneven grafting and crosslinking reactions. At the same time, there are too high local free radical concentrations leading to serious degradation, and the local free radical concentration is low. Insufficient graft crosslinking reaction is caused. In addition, another serious problem caused by the use of initiator is the self-polymerization of grafted monomers (multifunctional monomers), because grafted monomers are small molecules containing double bonds. And the reactivity is high. When the initiator decomposes to generate free radicals, the grafted monomers are easy to self-polymerize under the initiation of free radicals instead of grafting to the polypropylene macromolecular chain, which seriously affects the polypropylene macromolecular chain. Expected Effects of Grafting Monomers on Molecules

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