Multimodal Ethylene Copolymer Cable Jacketing
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Solution Overview
Problem
There is a need for polyethylene polymers with improved processability and mechanical properties for demanding wire and cable applications, where existing polymers often struggle with extrusion performance and surface smoothness due to issues like melt fracture behavior.
Innovation Solution
A cable comprising a conductor surrounded by one or more layers, with at least one layer being a jacketing layer made from a multimodal ethylene copolymer produced using a single site catalyst and activator, which has a specific molecular weight distribution and density, enhancing extrudability and mechanical properties such as flexibility and abrasion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If single site catalyst is used to produce polyethylene with controlled comonomer incorporation, then mechanical properties and flexibility are improved, but processability and extrusion performance deteriorate due to melt fracture behavior
Solution Approach 1:
The patent changes the molecular weight distribution parameters by using multimodal PE composition with specific Mz/Mw ratio (2.0-5.0) and controlled Mz value (100,000-1,000,000 g/mol). This parameter optimization resolves the contradiction by adjusting the high molecular weight fraction to improve processability while maintaining the mechanical properties provided by single site catalyst-produced polymer.
Solution Approach 2:
The patent creates a composite polymer system by combining multimodal PE composition with specific additives including process aids, lubricants, and stabilizers in controlled amounts. This composite approach allows the base polymer to provide mechanical strength while additives compensate for processability issues, enabling successful extrusion without melt fracture.
2Productivity
If multimodal PE composition is used to improve processability, then extrudability is enhanced, but surface smoothness deteriorates due to melt fracture
Solution Approach 1:
The patent optimizes rheological parameters by controlling the Mz/Mw ratio within 2.0-5.0 and Mz within 100,000-1,000,000 g/mol. This specific parameter range allows the polymer to flow smoothly during extrusion (improving extrudability) while maintaining surface integrity (preventing melt fracture), thus resolving the contradiction between productivity and manufacturing precision.
Solution Approach 2:
The patent introduces process aid additives as intermediary substances that mediate between the polymer melt and the extrusion process. These additives reduce melt fracture by modifying the flow characteristics, allowing high extrudability to be achieved while maintaining surface smoothness of the extruded cable layer.
3Strength
If high molecular weight fraction is increased to improve mechanical properties, then flexibility and abrasion resistance are enhanced, but processability deteriorates
Solution Approach 1:
The patent precisely controls the high molecular weight fraction by specifying Mz (100,000-1,000,000 g/mol) and Mz/Mw ratio (2.0-5.0). This controlled parameter approach ensures sufficient high MW content for mechanical strength and flexibility while preventing excessive viscosity that would harm processability, thus resolving the contradiction between strength and ease of manufacture.
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 multimodal ethylene copolymer provides improved processing properties, including reduced melt fracture and enhanced surface smoothness, along with improved mechanical properties like flexibility and abrasion resistance, making it suitable for high-performance wire and cable applications.
Implementation Method 1
The cable may be produced by applying, preferably by (co)extrusion, one or more layers on a conductor
Data Source
Figure 1~2
AI summary
The present invention relates to a cable comprising a conductor surrounded by one or more layers, wherein at least one layer comprises a polymer composition comprising a copolymer of ethylene with one or more comonomers, to a process for producing the cable and to a polymer composition suitable as a cable layer material.