Power Cable Insulation Polypropylene for Heat and Flexibility
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Solution Overview
Problem
Existing insulation materials for high-voltage electrical power cables, such as crosslinked polyethylene, are not recyclable and have poor heat resistance, while non-crosslinked polyethylene alternatives lack flexibility and low-temperature impact resistance, making them unsuitable for high-temperature operations.
Innovation Solution
A polypropylene resin composed of an ethylene-propylene impact copolymer with specific melting temperature, rubber content, and glass transition temperatures, enhancing flexibility, heat distortion resistance, and low-temperature impact resistance, and allowing for recyclability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If crosslinked polyethylene is used for insulation layer, then heat resistance is improved, but recyclability deteriorates
Solution Approach 1:
The patent changes the chemical structure parameters of polyethylene by controlling the branching degree and molecular weight distribution to achieve non-crosslinked polyethylene with melting point above 100°C, resolving the contradiction between heat resistance and recyclability
Solution Approach 2:
The patent creates a composite material system by blending different types of polyethylene (HDPE, LLDPE, LDPE) in specific ratios to achieve the desired melting point and mechanical properties while maintaining recyclability
2Ease of manufacture
If non-crosslinked polyethylene is used for insulation layer, then recyclability is improved, but heat resistance deteriorates
Solution Approach 1:
The patent changes the crystalline structure parameters of non-crosslinked polyethylene by controlling branching degree and molecular weight to elevate the melting point above 100°C, enabling both recyclability and adequate heat resistance
3Temperature
If polypropylene with high stiffness is used for insulation layer, then heat resistance is improved, but flexibility deteriorates
Solution Approach 1:
The patent creates a composite material by blending polypropylene with polyethylene in specific ratios (30-70 wt% PP, 70-30 wt% PE) to balance stiffness and flexibility while maintaining heat resistance through controlled melting point
4Temperature
If polypropylene is used for insulation layer, then heat resistance is improved, but low-temperature impact resistance deteriorates
Solution Approach 1:
The patent creates a composite material system blending polypropylene and polyethylene where the polyethylene component improves low-temperature impact resistance while the polypropylene provides heat resistance, achieving balanced performance
Data Source
Figure 1
AI summary
Provided is a polypropylene resin for an insulation layer of a power cable, which has excellent flexibility, heat distortion and low-temperature impact resistance and a high insulation breakdown strength to be suitably used for an insulation layer of an electrical power cable. In an exemplary embodiment, the polypropylene resin includes an ethylene-propylene impact copolymer consisting of a propylene homopolymer or an ethylene-propylene random copolymer (a), and ethylene-propylene copolymer rubber (b) polymerized therein, wherein the ethylene-propylene impact copolymer has a melting temperature (Tm) in a range of 145°C to 170°C, the content of a rubber component, measured by the content of a solvent extract (xylene solubles, room temperature) in the ethylene-propylene impact copolymer, is in a range of 35 wt% to 55 wt%, and the rubber component has two glass transition temperatures (Tg) in ranges of -25°C to -35°C and -45°C to -55°C.