Twisted Pair Cable Insulation for Low Dielectric Loss and Heat Resistance
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Solution Overview
Problem
Existing onboard transmission cables with twisted pair designs face challenges in achieving low dielectric constant and dielectric dissipation factor while maintaining heat resistance, especially when in contact with PVC materials.
Innovation Solution
A twisted pair cable design featuring an insulator made from a resin composition containing polypropylene, a phenol-based antioxidant, and a copper inhibitor, which achieves a relative dielectric constant of 2.0 to 2.5 and a dielectric dissipation factor of 1.0×10−3 or less, while maintaining heat resistance and compatibility with PVC.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an antioxidant and copper inhibitor are added to the resin constituting the insulator, then the heat resistance and durability are improved, but the dielectric constant and dielectric dissipation factor increase
Solution Approach 1:
The patent changes the chemical parameters of the resin by selecting specific types of antioxidants (phenol-based, sulfur-based, phosphite-based) and copper inhibitors, and by optimizing their addition amounts. This allows achieving the required heat resistance while controlling the dielectric properties through careful parameter selection
Solution Approach 2:
The patent uses a composite resin composition containing polypropylene as the base resin combined with specific antioxidants and copper inhibitors. This composite approach allows balancing the conflicting requirements of heat resistance (provided by antioxidants/copper inhibitors) and low dielectric loss (provided by polypropylene matrix)
2Loss of energy
If polyethylene with low melting point is used in the insulator, then the dielectric constant is reduced, but the heat resistance at overload is insufficient
Solution Approach 1:
The patent changes the fundamental parameter of the base resin from polyethylene to polypropylene. Polypropylene has a higher melting point and better heat resistance while maintaining acceptable dielectric properties, thus resolving the contradiction between low dielectric constant and heat resistance
3Duration of action of stationary object
If the insulator is in contact with PVC wire harness for a long time under high temperature, then the plasticizer from PVC migrates to the insulator, but this causes degradation of the insulator and sheath
Solution Approach 1:
The patent uses antioxidants (particularly phenol-based and sulfur-based) that not only provide oxidation protection but also act as barriers against plasticizer migration. The antioxidants scavenge free radicals and prevent the degradation reactions that would otherwise be accelerated by plasticizer migration, thus converting the harmful migration process into a manageable condition
Solution Approach 2:
The antioxidant and copper inhibitor components act as intermediary protective agents between the insulator resin and the migrating plasticizer from PVC. These additives absorb the harmful effects of plasticizer migration and prevent direct damage to the polypropylene matrix and sheath materials
Data Source
AI summary
A twisted pair cable is a twisted pair cable obtained by twisting two electric wires each of which includes a conductor portion and an insulator covering an outer periphery of the conductor portion. The insulator is made of a resin composition containing polypropylene, an antioxidant, and a copper inhibitor. The insulator has an external appearance abnormality development time exceeding 3,000 hours during a test of compatibility with PVC in contact with PVC at 100° C. The insulator has a relative dielectric constant of 2.0 to 2.5 and a dielectric dissipation factor of 1.0×10−3 or less when m electric field having a frequency of 1 GHz is applied.