Bimodal polyethylene resin for large-caliber thick-wall low-sag pipes and preparation method of bimodal polyethylene resin

Abstract

The invention provides a bimodal polyethylene resin for large-caliber thick-wall low-sag pipes and a preparation method of the bimodal polyethylene resin. The resin comprises a high-molecular-weight part and a low-molecular-weight part, and the mass ratio of the low-molecular-weight part to the high-molecular-weight part is 3: 7-7: 3; wherein the number-average molecular weight Mn of the resin ranges from 2000 to 10000, the weight-average molecular weight Mw of the resin ranges from 100000 to 400000, the Mw / Mn of the resin ranges from 10 to 200, the melt flow rate MFRs of the resin ranges from0.2 to 1.0g / 10min, and the resin density ranges from 0.945g / cm<3> to 0.960g / cm<3>. The bimodal polyethylene resin provided by the invention can be prepared by a reactor formed by connecting a loop reactor and a fluidized bed reactor in series. The bimodal polyethylene resin has improved mechanical properties, excellent processability and excellent strength and sag resistance, and is suitable forpreparing large-caliber thick-wall low-sag pipes.

Description

technical field [0001] The invention relates to the technical field of polymer pipes, in particular to a bimodal polyethylene pipe resin used for large-diameter thick-walled low-sag pipes and a preparation method thereof. Background technique [0002] Tubing in polymeric materials is often used in a variety of applications, such as fluid transfer. When used to transport fluids such as liquids or gases, the fluid to be transported needs to be pressurized during the transport process, and the temperature of the fluid will also change, usually in the range of 0°C to 50°C. This kind of fluid transport tube is pressure tube. The so-called "pressure pipe" refers to a pipe that is subject to positive pressure (ie, the pressure inside the pipe is higher than the pressure outside the pipe) during use. At present, the pressure pipes made of polymer materials are mostly made of polyolefin plastics, and the commonly used polyolefin plastics are unimodal polyethylene, but this conventi...

AI Technical Summary

Problems solved by technology

At present, in the existing polyethylene resin polymerization process, the distribution of high molecular weight polyethylene and low molecular weight polyethylene is uncontrollable, and the molecular weight distribution is unreasonable, resulting in the physical and mechanical strength and long-term performance of large-diameter thick-walled low-melt sagging pipes. , the post-processing is more difficult, and it is easy to produce a tube with a thicker tube wall at the bottom of the tube and a thinner wall distribution at the top of the tube, and the sagging phenomenon occurs

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