Polypropylene Cable Insulation for Flexible Recyclable HV Cables
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing insulation materials for medium and high voltage cables, such as PVC and XLPE, fail to provide a balanced combination of flexibility, mechanical properties, impact resistance, and electrical breakdown strength, and are not environmentally friendly or recyclable.
Innovation Solution
A polypropylene composition comprising 80.0 to 99.0 wt.% of a propylene copolymer with ethylene and alpha-olefins, and 1.0 to 20.0 wt.% of an ethylene polymer, optimized for melt flow rate, xylene cold soluble fraction, and density, which forms a heterophasic structure with distinct glass transition temperatures, enhancing flexibility and mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If PVC is used as insulation material with softeners to maintain flexibility, then flexibility is improved, but environmental harm increases and temperature resistance deteriorates
Solution Approach 1:
The invention changes the material parameter from PVC to polypropylene composition, eliminating the need for harmful softeners while achieving flexibility through the copolymer structure with 10-16 wt% comonomer units. This parameter change resolves the contradiction by providing flexibility without environmental harm.
Solution Approach 2:
The invention uses a composite polypropylene composition comprising a copolymer of propylene with comonomer units (ethylene and/or alpha-olefins) combined with an ethylene polymer. This composite structure provides intrinsic flexibility through the copolymer architecture without requiring harmful plasticizers, thus resolving the contradiction between flexibility and environmental harm.
2Reliability
If XLPE is used for high voltage cables to achieve high breakdown strength, then electrical performance is improved, but recyclability deteriorates
Solution Approach 1:
The invention changes the chemical structure parameter from crosslinked XLPE to thermoplastic polypropylene composition. This parameter change maintains electrical breakdown strength while enabling recyclability through remelting, as the thermoplastic nature allows repeated processing without chemical degradation.
Solution Approach 2:
The invention extracts the crosslinking component from the insulation material system, replacing it with a thermoplastic polypropylene composition that achieves comparable electrical performance without the crosslinked structure. This extraction of the crosslinking feature enables recyclability while maintaining reliability.
3Ease of manufacture
If thermoplastic polypropylene is used to enable recyclability, then recyclability is improved, but electrical breakdown strength deteriorates
Solution Approach 1:
The invention creates a composite polypropylene system combining a copolymer with specific comonomer content (10-16 wt%) and an ethylene polymer. This composite structure achieves electrical breakdown strength comparable to XLPE while maintaining thermoplastic recyclability, resolving the contradiction between recyclability and electrical performance.
Solution Approach 2:
The invention optimizes the comonomer content parameter to 10-16 wt% and controls the molecular weight distribution (Mw/Mn ratio of 3.0-8.0) to achieve the right balance between processability, flexibility, and electrical breakdown strength. These parameter changes enable thermoplastic material to meet high voltage cable requirements.
4Temperature
If PVC operates at high temperatures with special plasticizers, then temperature resistance is improved, but flexibility deteriorates
Solution Approach 1:
The invention changes the base material from PVC to polypropylene composition, which inherently provides both high temperature resistance and flexibility without requiring special plasticizers. The copolymer structure with controlled comonomer content maintains flexibility across a wide temperature range from -40°C to +100°C.
Data Source
AI summary
The present invention relates to a polypropylene composition comprising (A) from 80.0 to 99.0 wt.-% of a copolymer of propylene and comonomer units selected from ethylene and alpha-olefins having from 4 to 12 carbon atoms having a total amount of comonomer units of from 10.0 to 16.0 wt %, based on the total amount of monomer units of the copolymer of propylene (A); a melt flow rate MFR2 of from 0.5 to 2.5 g/10 min; a xylene cold soluble (XCS) fraction in a total amount of from 25.0 to 50.0 wt %, based on the total weight amount of the copolymer of propylene (A); and (B) from 1.0 to 20.0 wt.-% of an ethylene polymer having a density of from 915 to 960 kg/m3; and a melt flow rate MFR5 (190° C., 5 kg) of from 0.05 to 5.0 g/10 min, an article comprising said polypropylene composition, preferably a cable comprising an insulation layer comprising said polypropylene composition, and the use of said polypropylene composition as cable insulation for medium and high voltage cables.