PROCESS FOR MAKING ETHYLENE POLYMER BLENDS WITH CONTROLLED LONG-CHAIN BRANCHING

摘要

A high-temperature solution process for making an ethylene polymer blend having a controlled degree of long-chain branching is disclosed. Ethylene is polymerized in the presence of a first Ziegler-Natta catalyst comprising titanium, magnesium, and aluminum in the absence of hydrogen to produce a first ethylene polymer component having substantial long-chain branching. A second ethylene polymer component having little or no long-chain branching is also prepared. Both polymerizations are performed at a temperature from 140°C to 250°C. The first and second ethylene polymer components are combined to give a polymer blend. The degree of long-chain branching in the blend is controlled by adjusting the relative amounts of the first and second ethylene polymer components. The invention enables the preparation of valuable products having a pre-determined degree of long-chain branching using readily available Zeigler-Natta catalysts, commercially practiced techniques, and conventional equipment.