Homogeneous Crosslinkable Polyethylene Production via Segmented Extrusion
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Solution Overview
Problem
Current methods for producing crosslinkable polyethylene (XLPE) are inefficient due to premature crosslinking, leading to increased energy consumption and difficulty in processing, as well as a lack of homogeneity and flexibility in the production process.
Innovation Solution
A production system that includes an on-line contamination control unit, automatic reactive dosing, and homogenization and absorption units to ensure contamination separation, precise dosing of antioxidants and dicumyl peroxide, and homogenization of polyethylene to achieve a more homogeneous and efficient crosslinking process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dicumyl peroxide is mixed with polyethylene before extrusion, then crosslinking occurs during processing, but this causes premature crosslinking that makes XLPE more difficult to process and increases energy consumption
Solution Approach 1:
The patent divides the crosslinking process into two separate stages: (1) mixing polyethylene with crosslinking agent (silane) before extrusion to ensure homogeneous distribution, and (2) performing actual crosslinking after extrusion through moisture exposure or heat treatment. This segmentation prevents premature crosslinking during extrusion while ensuring complete crosslinking in the final product, thereby resolving the contradiction between crosslinking effectiveness and processing ease.
Solution Approach 2:
The patent applies preliminary action by pre-mixing the crosslinking agent with polyethylene before extrusion, but delaying the actual crosslinking reaction until after extrusion. The silane-modified polyethylene is extruded first, then crosslinked through controlled exposure to moisture or heat in subsequent processing steps. This preliminary preparation without immediate reaction eliminates processing difficulties while maintaining crosslinking effectiveness.
2Manufacturing precision
If multiple process steps are used for mixing and drying polyethylene with peroxide, then crosslinking homogeneity improves, but processing time and energy consumption increase
Solution Approach 1:
The patent merges the mixing and extrusion steps into a single continuous operation using a twin-screw extruder. The crosslinking agent is fed together with polyethylene into the extruder, where mixing and shaping occur simultaneously in one integrated process. This eliminates separate mixing and drying steps, achieving homogeneous crosslinking distribution while significantly reducing processing time and energy consumption.
Solution Approach 2:
The patent implements continuous action by using a continuous extrusion process where polyethylene and crosslinking agent are continuously mixed, melted, and shaped in one uninterrupted flow through the extruder. This continuous process replaces batch-wise mixing and drying operations, maintaining homogeneous mixing while reducing total processing time and eliminating idle time between steps.
3Ease of operation
If peroxide is fed to extruder separately after polyethylene, then premature crosslinking is avoided, but mixing homogeneity deteriorates
Solution Approach 1:
The patent introduces silane-modified polyethylene as an intermediary material. Instead of mixing raw peroxide with polyethylene, the crosslinking agent is first grafted onto polyethylene chains to create silane-modified polyethylene. This intermediary form ensures uniform distribution of crosslinking sites throughout the polymer matrix while preventing premature crosslinking, as the actual crosslinking reaction only occurs when the modified polyethylene is exposed to moisture or heat after extrusion.
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 system enables faster, cleaner, and more flexible production of XLPE with reduced energy consumption and contamination, resulting in a more homogeneous product with improved mechanical properties and reduced processing time.
Implementation Method 1
homogenization of polyethylene to achieve a more homogeneous and efficient crosslinking process
Implementation Method 2
absorption process is applied at 50 °C for 30 hours
Data Source
Figure 1
AI summary
The present invention relates to production method of crosslinkable polyethylene (XLPE). Objective of the present invention is to realize production of a crosslinked polyethylene to produce a crosslinked polyethylene in a shorter time compared to conventional applications because it is more homogeneous, clearer and has fewer process steps.