Polyethylene Composition for Drip Irrigation Pipes
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Solution Overview
Problem
Current polyethylene compositions used in drip irrigation pipes and tapes face challenges with insufficient UV resistance due to uneven carbon black distribution, inconsistent mixing ratios, and suboptimal homogeneity, leading to early failures and inconsistent quality, especially at high production line speeds and thin wall thicknesses.
Innovation Solution
A polyethylene composition comprising at least 60 wt.% multimodal ethylene polymer and 0.5 to 13 wt.% carbon black, with a specific MFR and density range, ensuring even carbon black distribution and improved mechanical properties, processed into pellets for enhanced pipe production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a dry blend of different components is used, then the mixing capacity of single screw extruders is exceeded, but the carbon black is not evenly distributed in the final pipe or tape
Solution Approach 1:
The patent applies preliminary action by pre-mixing carbon black with polyethylene powder in a tumble mixer before extrusion. This pre-mixing step ensures uniform distribution of carbon black throughout the polyethylene matrix, eliminating the distribution problems that would occur with direct dry blending in the extruder. The pre-mixed blend is then ready for efficient extrusion processing.
2Ease of manufacture
If a dry blend is prepared prior to tape extrusion, then the preparation process is laborious and time consuming, but the mixing ratios may vary from time to time
Solution Approach 1:
The patent uses preliminary action by pre-mixing components in controlled ratios using a tumble mixer before extrusion. This pre-mixing step establishes consistent mixing ratios that are maintained throughout production, eliminating variability issues while streamlining the overall preparation process.
Solution Approach 2:
The patent introduces an intermediary pre-mixing step using a tumble mixer as a mediating device between component storage and extrusion. This intermediary step ensures consistent mixing ratios are achieved and maintained, acting as a buffer that decouples the precision requirements from the main extrusion process.
3Ease of operation
If polymer composition with high level of inhomogeneities is used, then the processability is not optimal, but high line production line speeds and thin wall thicknesses are not achieved
Solution Approach 1:
The patent applies preliminary action by pre-mixing carbon black with polyethylene powder in specific ratios (0.5-13 wt%) using a tumble mixer before extrusion. This pre-mixing ensures homogeneous distribution of carbon black, which optimizes processability and enables high line speeds with thin wall thicknesses. The pre-prepared blend eliminates inhomogeneities that would otherwise limit production capabilities.
Data Source
AI summary
The present invention relates to pellets comprising a polyethylene composition, a pipe or pipe system comprising the pellets as well as a process for the preparation of such a pipe or pipe system.