In-kettle nucleating method for preparing high-performance polypropylene

Abstract

The invention discloses an in-kettle nucleating method for preparing high-performance polypropylene. A defined amount of triethyl aluminum, an external electron donor, a nucleating agent, and a catalyst are added in a kettle, and react at a set temperature and a pressure, wherein the mol ratio of the catalyst to a cocatalyst to the external electron donor, namely Ti:Al:Si, is (1-20):(250-300):(20-100), the polypropylene is prepared through in-kettle nucleating; and the prepared polypropylene has modulus of elasticity in static bending of above 2 MPa, tensile strength of above 34 MPa, high combination property, and better economy and application values.

Description

Technical field: [0001] The invention relates to a method for preparing high-performance polypropylene by nucleation in a kettle. Background technique: [0002] Polypropylene (PP) has excellent rigidity, processability and electrical insulation properties. It is a general-purpose polymer material with excellent comprehensive properties. It has been widely used in electrical appliances, automobiles, construction, packaging and other fields. Due to the shortcomings of polypropylene, such as poor notched impact performance, insufficient high-temperature rigidity, and low static compressive strength, nucleating agents need to be added to improve crystallinity and purify the size of spherulites. [0003] At present, the industrial production of high crystallinity polypropylene is mainly the method of adding nucleating agent outside the kettle and the method of synthesis in the kettle. The process of adding nucleating agent outside the kettle is simple, but it has the disadvant...

AI Technical Summary

Problems solved by technology

However, during the polymerization in the kettle, the nucleating agent will react with the alkylaluminum in the catalyst to varying degrees, affecting the polymerization effect, and even making the catalyst completely inactive, and some nucleating agents (such as sorbitol and amides) cannot be used directly. Due to the reaction nucleation polymerization reaction, the development of this method is restricted. Most of the patents use inert substances (such as talcum powder, silica gel, polyolefin, etc.) as nucleating agents to directly prepare high-performance polypropylene in the kettle, such as CN1215061, the shortcoming of this method is that the talcum powder consumption is bigger, causes the density of product to increase, and nucleation effect is bad, and the crystallization temperature of polymer is lower