Multimodal Ethylene Copolymer Pipes for Pressure and Flexibility
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Pipes made of high-density polyethylene lack flexibility and sufficient mechanical properties for high-pressure fluid transportation, leading to issues with coiling and homogeneity, and often contain volatile compounds that can affect water quality.
Innovation Solution
Development of a multimodal ethylene copolymer with specific density, molecular weight, and melt index ranges, produced through a multistage polymerization process using a metallocene catalyst, which results in flexible pipes with reduced volatile content and improved homogeneity, suitable for PE80 or PE100 classification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high-density polyethylene is used to ensure good mechanical properties and pressure resistance, then the pipes can withstand pressure, but the pipes become too rigid and cannot be coiled
Solution Approach 1:
The patent applies parameter changes by precisely controlling the density of the polyethylene material within a specific range (940-960 kg/m³) and adjusting molecular weight distribution through multistage polymerization. This allows the material to maintain sufficient mechanical strength for pressure resistance while achieving enough flexibility for coiling applications.
Solution Approach 2:
The patent uses composite material principles by creating a multimodal polyethylene with multiple molecular weight components (combining components with different molecular weights in specific ratios). This composite molecular structure provides both the strength needed for pressure resistance and the flexibility required for coiling, effectively resolving the contradiction between these two properties.
2Strength
If multimodal polyethylene with density of 947-953 kg/m³ is used, then good mechanical properties are achieved, but the pipes are not flexible enough for coiling
Solution Approach 1:
The patent narrows and shifts the density parameter range to 940-960 kg/m³ (from the conventional 947-953 kg/m³) and optimizes the molecular weight distribution. This parameter optimization allows the material to achieve the right balance between mechanical strength and flexibility, enabling both good mechanical properties and coiling capability.
3Ease of manufacture
If conventional polymerization process is used, then production is simpler, but the polymer composition has poor homogeneity and excessive volatiles
Solution Approach 1:
The patent applies segmentation by dividing the polymerization process into multiple stages (multistage polymerization), where each stage produces polymer components with specific molecular weight ranges. This segmented approach ensures better homogeneity and controlled volatile content while maintaining reasonable process complexity through systematic stage management.
Solution Approach 2:
The patent optimizes polymerization parameters including temperature, pressure, and catalyst composition across different stages. By carefully controlling these parameters, the process achieves high homogeneity and low volatile content (at most 100 ppm) while keeping the manufacturing process feasible and systematic.
4Ease of manufacture
If polymer composition contains volatile compounds, then the material may be easier to process, but the volatiles migrate into water causing odour problems
Solution Approach 1:
The patent optimizes polymerization parameters and material composition to reduce volatile compound content to at most 100 ppm. This parameter optimization ensures that the material remains processable while eliminating the harmful odour effect caused by volatile migration into water.
Solution Approach 2:
The patent converts the potential harm of volatile compounds by reducing their content to minimal levels through optimized polymerization processes. This transforms the situation from harmful (odour-causing volatiles) to beneficial (safe, odour-free water transportation) while maintaining necessary material processability.
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 solution provides flexible pipes with enhanced mechanical properties and reduced volatile compounds, enabling them to meet PE80 or PE100 standards without excessive inhomogeneities, ensuring safe and odor-free water transportation.
Implementation Method 1
the multimodal copolymer is produced in a multistage polymerization process in the presence of a metallocene catalyst
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 960 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 SHI27/210 of from 2 to 50. The compositions further have a level of volatile compounds of at most 100 ppm by weight and/or a homogeneity rating of at most 3. In addition the multimodal copolymer comprises: (A) from 35 to 60 % 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 40 to 65 % 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 935 kg/m3.