Multimodal Ethylene Copolymer Pipes for Pressure and Flexibility
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Solution Overview
Problem
Pipes made of HDPE lack flexibility for coiling and sufficient mechanical properties for high-pressure fluid transport, while flexible LLDPE pipes often fail to meet mechanical strength requirements for water or gas transportation.
Innovation Solution
Development of a multimodal ethylene copolymer with specific molecular weight, density, and composition ranges, produced through a multistage polymerization process using a single-site catalyst, which allows for the creation of flexible and mechanically strong pipes that can be coiled and used for pressure applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If pipes are made of HDPE (high density polyethylene), then mechanical strength and pressure resistance are improved, but flexibility is worsened
Solution Approach 1:
The patent creates a composite polymer material combining HDPE and LLDPE in specific ratios (30-70% HDPE and 70-30% LLDPE). This composite approach allows the pipe to simultaneously achieve the mechanical strength from HDPE and the flexibility from LLDPE, resolving the contradiction between these two opposing properties.
Solution Approach 2:
The patent modifies the compositional parameters of the polymer material by controlling the density, molecular weight distribution, and composition ratio of the polymer blend. By adjusting these parameters, the material achieves optimal balance between strength and flexibility, enabling pipes that can be coiled while maintaining pressure resistance.
2Ease of operation
If pipes are made of LLDPE (linear low density polyethylene) to improve flexibility, then ease of coiling is improved, but mechanical strength is worsened
Solution Approach 1:
The patent creates a composite polymer material combining HDPE and LLDPE in specific ratios (30-70% HDPE and 70-30% LLDPE). This composite approach allows the pipe to simultaneously achieve the mechanical strength from HDPE and the flexibility from LLDPE, resolving the contradiction between these two opposing properties.
3Adaptability or versatility
If multimodal polyethylene is used to achieve both flexibility and mechanical properties, then adaptability is improved, but manufacturing complexity is worsened
Solution Approach 1:
The patent modifies the compositional parameters of the polymer material by controlling the density, molecular weight distribution, and composition ratio of the polymer blend. By adjusting these parameters, the material achieves optimal balance between strength and flexibility, enabling pipes that can be coiled while maintaining pressure resistance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The resulting polymer composition enables pipes with enhanced flexibility and mechanical strength, meeting PE80 standards for transporting water or gas under pressure, with improved Charpy Impact Strength and shear thinning properties.
Implementation Method 1
polymerising, in a first polymerisation step in a first polymerisation zone, in the presence of a single site polymerisation catalyst, ethylene, hydrogen and optionally one or more alpha-olefines having 4 to 10 carbon atoms to form the low molecular weight component (A)
Data Source
AI summary
The present invention deals with polymer compositions suitable for making pipes. The compositions comprise a multimodal copolymer of ethylene and one or more alpha-olefins having from 4 to 10 carbon atoms wherein the multimodal ethylene copolymer has a density of from 924 to 935 kg/m3, a melt index MFR5 of from 0.5 to 6.0 g/10 min, a melt index MFR2 of from 0.1 to 2.0 g/10 min and a shear thinning index SHI2.7/210 of from 2 to 50. In addition the multimodal copolymer comprises: (A) from 30 to 70 % by weight, based on the combined amount of components (A) and (B), of a low molecular weight ethylene polymer selected from ethylene homopolymer and a copolymer of ethylene and one or more alpha-olefins having from 4 to 10 carbon atoms and having a weight average molecular weight of from 5000 to 100000 g/mol and a density of from 945 to 975 kg/m3; and (B) from 30 to 70 % by weight, based on the combined amount of components (A) and (B), of a high molecular weight copolymer of ethylene and one or more alpha-olefins having from 4 to 10 carbon atoms and having a weight average molecular weight of from 100000 to 1000000 g/mol and a density of from 890 to 929 kg/m3.