Power Cable Insulation Composition for Flexibility and Whitening Resistance
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Solution Overview
Problem
Current insulating layers for power cables, such as those using cross-linked polyethylene, are not recyclable and have limitations in flexibility and electrical properties, while polypropylene-based layers suffer from poor installation properties and insufficient electrical performance due to heterogeneous mixing with olefin-based rubbers.
Innovation Solution
A polypropylene resin composition incorporating 70-90 parts by weight of propylene block copolymer with ethylene-propylene rubber dispersed in a propylene-ethylene random copolymer, 5-20 parts by weight of polyolefin elastomer, and 5-20 parts by weight of high molecular weight atactic polypropylene, optimized for improved flexibility, electrical properties, and whitening resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If polypropylene is used as insulating layer material, then heat resistance and recyclability are improved, but flexibility deteriorates due to high rigidity
Solution Approach 1:
The patent uses a composite material system consisting of polypropylene resin as the base material combined with specific elastomeric modifiers (ethylene-propylene rubber and polyolefin elastomer) to create a multi-phase structure. This composite approach allows the polypropylene matrix to provide heat resistance while the dispersed elastomeric phases provide flexibility, resolving the contradiction between rigidity and flexibility.
Solution Approach 2:
The patent modifies the physical and chemical parameters of the polypropylene system by controlling the molecular weight, composition, and phase structure of the elastomeric modifiers. Specifically, it uses ethylene-propylene rubber with 30-60 wt% ethylene content and polyolefin elastomer with specific molecular weight ranges to achieve the desired balance between heat resistance and flexibility without sacrificing the inherent advantages of polypropylene.
2Ease of operation
If olefin-based rubber is added to improve flexibility, then flexibility is improved, but electrical properties deteriorate due to heterogeneous mixing and whitening phenomenon
Solution Approach 1:
The patent introduces a specific type of propylene block copolymer as an intermediary material that is compatible with both the polypropylene matrix and the elastomeric modifiers. This intermediary phase acts as a bridge, improving the interfacial adhesion between the heterogeneous components and preventing the formation of microcrazes at the interface, thereby maintaining electrical properties while achieving flexibility improvement.
Solution Approach 2:
The patent achieves homogeneous mixing by carefully selecting the chemical composition and structure of the elastomeric modifiers to be compatible with the polypropylene matrix. The use of propylene-based elastomers (ethylene-propylene rubber and polyolefin elastomer) ensures chemical similarity and compatibility, reducing phase separation and heterogeneity. This homogeneous structure prevents interface boundary formation and eliminates the whitening phenomenon that would otherwise degrade electrical properties.
3Ease of operation
If rubber phase content is increased to improve softness, then flexibility is improved, but mechanical properties deteriorate and whitening occurs
Solution Approach 1:
The patent optimizes the parameters of the elastomeric modifiers, specifically using ethylene-propylene rubber with 30-60 wt% ethylene content and polyolefin elastomer with molecular weights in specific ranges (20,000-100,000 g/mol for POE). These parameter selections ensure that the rubber phases provide sufficient softness and flexibility while maintaining adequate mechanical strength and preventing whitening phenomenon during installation.
Data Source
AI summary
Disclosed are a resin composition for an insulating layer of a recyclable power cable, and a molded article using the resin composition, wherein the resin composition for an insulating layer of a power cable has excellent whitening resistance while satisfying excellent flexibility and electrical properties. The present invention provides a polypropylene resin composition for an insulating layer of a power cable, and a power cable using the polypropylene resin composition, wherein the polypropylene resin composition includes 70 parts by weight to 90 parts by weight of a propylene block copolymer in which ethylene-propylene rubber (EPR) is dispersed in a propylene-ethylene random copolymer, 5 parts by weight to 20 parts by weight of a polyolefin elastomer (POE), and 5 parts by weight to 20 parts by weight of high molecular weight atactic polypropylene (PP) having a weight average molecular weight of 100,000 g/mol or greater.