Crosslinked Polyethylene Cable Composition With Low Methane Formation
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Solution Overview
Problem
Existing cable manufacturing processes face issues with premature crosslinking agent decomposition during extrusion, leading to unevenness, discolouration, and volatile peroxide decomposition products like methane, which pose safety risks and require costly degassing steps, affecting the quality and efficiency of high-voltage cable production.
Innovation Solution
A cable composition comprising polyethylene, a crosslinking agent, and nitrogen-containing antioxidants, with controlled vinyl group content and crosslinking agent amounts, minimizes premature crosslinking and volatile decomposition products, ensuring stable crosslinking and reduced methane formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the crosslinking agent is added to the polymer composition prior to extrusion, then crosslinking improves heat and deformation resistance and mechanical strength, but the crosslinking agent decomposes during extrusion causing premature crosslinking, surface unevenness, and discolouration
Solution Approach 1:
The patent applies preliminary action by pre-mixing the crosslinking agent with the polymer composition before extrusion, allowing the crosslinking agent to be uniformly distributed throughout the material. This preliminary preparation ensures that crosslinking occurs uniformly after extrusion rather than during the process, preventing surface unevenness while maintaining mechanical strength improvements.
Solution Approach 2:
The patent utilizes parameter changes by controlling the decomposition temperature and rate of the crosslinking agent. By selecting crosslinking agents with appropriate decomposition characteristics and controlling processing parameters, the patent ensures that crosslinking occurs at the desired stage (after extrusion) rather than during extrusion, thereby avoiding surface defects while achieving the desired mechanical properties.
2Stability of the object's composition
If the extrusion temperature is increased to obtain proper melting and homogenisation, then the polymer composition melts uniformly, but the crosslinking agent decomposes prematurely
Solution Approach 1:
The patent applies parameter changes by optimizing the extrusion temperature profile and the decomposition characteristics of the crosslinking agent. By carefully selecting processing parameters and crosslinking agent properties, the patent achieves uniform melting and homogenization of the polymer composition without triggering premature decomposition of the crosslinking agent, thus maintaining both composition stability and agent reliability.
3Productivity
If crosslinking is performed at elevated temperature to increase crosslinking speed, then the target crosslinking degree is reached faster, but volatile peroxide decomposition products like methane are formed
Solution Approach 1:
The patent applies parameter changes by optimizing the crosslinking temperature and duration to achieve the desired crosslinking degree with minimized volatile decomposition products. By carefully controlling the crosslinking process parameters, the patent maintains high crosslinking speed while reducing methane formation to acceptable levels.
Solution Approach 2:
The patent utilizes composite materials by combining the polymer composition with specifically selected crosslinking agents and additives that modify the decomposition behavior. This composite approach allows the system to achieve fast crosslinking while minimizing the formation of harmful volatile products like methane through the synergistic effects of the composite formulation.
4Reliability
If a degassing step is added to remove volatile decomposition products, then safety and quality are improved, but production time and cost increase
Solution Approach 1:
The patent applies the extraction principle by removing or minimizing the formation of volatile decomposition products through careful selection of crosslinking agents and optimization of crosslinking conditions. By extracting the harmful byproducts from the system through parameter optimization, the patent reduces or eliminates the need for separate degassing steps, thereby maintaining cable quality while reducing production time.
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 composition achieves desirable crosslinking levels with significantly lower methane content, allowing for shorter or eliminated degassing times, enhancing production efficiency and safety in high-voltage cable manufacturing.
Implementation Method 1
the crosslinking agents, e.g. peroxides, decompose generating free radicals
Implementation Method 2
the crosslinking agents, e.g. peroxides, decompose generating free radicals
Implementation Method 3
the antioxidant(s) is/are nitrogen containing antioxidant(s) and the polymer composition contains a total amount of vinyl groups which is B vinyl groups per 1000 carbon atoms... with the proviso that the antioxidants with CAS Number 152261-33-1 and CAS Number 193098-40-7 are excluded
Data Source
AI summary
The invention relates to a cable comprising layer(s), which layer(s) is/are obtained from a polymer composition comprising a polyethylene, a crosslinking agent and antioxidant(s), characterized in that the polymer composition contains a total amount of vinyl groups which is B vinyl groups per 1000 carbon atoms, and B1 ≤ B, wherein B1 is 0.12, when measured prior to crosslinking according to method ASTM D6248-98, the crosslinking agent is present in an amount which is Z wt%, prior to crosslinking, based on the total amount (100 wt%) of the polymer composition, and Z1 ≤ Z ≤ Z2, wherein Z1 is 0.005 and Z2 is 2.0, and that the antioxidant(s) is/are nitrogen containing antioxidant(s) being present in an amount which is W wt%, prior to crosslinking, based on the total amount (100 wt%) of the polymer composition, and W1 ≤ W ≤W2, wherein W1 is 0.005 and W2 is 1.0, the cable, e.g. a power cable,and processes for producing the cable; the cable useful in different end applications, such as wire and cable (W&C) applications.