Multi-phase copolymer polypropylene in-reactor alloy and preparation method thereof

Abstract

The invention discloses a multi-phase copolymer polypropylene in-reactor alloy and a preparation method thereof. In the method, a compound catalyst which is prepared by combining a Ziegler-Natta catalyst and a metallocene catalyst is adopted; propylene polymerization and ethylene / alpha-olefin copolymerization which are sequentially performed are catalyzed by the components of the two catalysts together; thus a polypropylene resin phase which is mainly prepared under the action of the Ziegler-Natta catalyst is uniformly mixed with an ethylene / alpha-olefin random copolymer rubber phase which is mainly prepared under the action of the metallocene catalyst in a polymerizer; and in the method, the ethylene / alpha-olefin block copolymer which is generated under the action of the Ziegler-Natta catalyst can be utilized as a compatilizer between the resin phase and the rubber phase, so that dispersion stability of the two phases (the resin phase and the rubber phase) is guaranteed, and balance between rigidity and toughness of the material is effectively realized.

Description

technical field [0001] The invention relates to a heterogeneous copolymer polypropylene kettle alloy and a preparation method thereof. Background technique [0002] Polypropylene, as one of the most widely used synthetic polymer materials, has developed rapidly since its industrialization in the 1950s. Its products have been widely used in the fields of automobiles, construction, home appliances, packaging and agriculture. Polypropylene alloy is a mixture of polypropylene and other olefin polymers (mostly a mixture of polypropylene and ethylene / α-olefin random copolymer). Because it has better low-temperature toughness than ordinary polypropylene, it is used as a high-impact The material has a wide range of applications in fields such as automobile manufacturing, home appliances, construction and packaging. The traditional preparation method of polypropylene alloy is the melt blending method, that is, the mechanical mixing of polypropylene and ethylene / α-olefin random copol...

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Problems solved by technology

However, multi-stage reactor technology usually initiates polymerization by a single catalytic system, and the same catalyst plays a catalytic role in each stage of reactor, so that it is impossible to achieve optimal conditions in each stage of reactor, especially in a wide range of reactors. The titanium-based catalyst (Ziegler-Natta catalyst) used for polypropylene synthesis has poor catalytic copolymerization ability, so in the stage of ethylene / α-olefin copolymerization, copolymers with long homopolymer molecular chain segments are usually obtained, which cannot achieve rubber Diversity adjustment of phase molecular structure, so the control of material properties is very limited, and only a few grades of polypropylene inner alloy products can be prepared

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