Molded Wire Insulation Adhesion via Segmented Crosslinked Layers
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Solution Overview
Problem
Molded wires and cables face challenges with adhesion issues between insulation layers, leading to poor air tightness, handling difficulties, and reduced mechanical strength, especially when using crosslinked polyethylene resin or thermoplastic polyurethane, which compromises ease of handling and terminal processability.
Innovation Solution
A configuration comprising a crosslinked ethylene resin insulation inner layer and a crosslinked thermoplastic polyurethane insulation outer layer with controlled gel fractions and surface roughness, fused with a resin molded body, enhances adhesion and air tightness while improving handling and mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermoplastic polyurethane is used for the insulation to achieve excellent adhesiveness to the molding resin, then air tightness is improved, but the wires adhere to each other causing reduced ease of handling and work efficiency
Solution Approach 1:
The patent divides the insulation into two separate layers: an inner layer made of crosslinked polyethylene resin and an outer layer made of thermoplastic polyurethane. This segmentation allows each layer to perform its specific function - the inner layer prevents wire adhesion and provides heat resistance, while the outer layer ensures adhesion to the molding resin for air tightness.
Solution Approach 2:
Different regions of the insulation have different material properties tailored to local requirements. The inner layer near the conductor has low adhesion properties to prevent wire sticking, while the outer layer at the surface has high adhesion properties to bond with the molding resin. This local differentiation resolves the contradiction between ease of handling and air tightness.
2Temperature
If thermoplastic polyurethane is crosslinked to improve heat resistance, then heat resistance is improved, but adhesion to the molding resin decreases causing insufficient air tightness
Solution Approach 1:
The patent separates the heat resistance function from the adhesion function by using different materials in different layers. The inner layer uses crosslinked polyethylene resin specifically for heat resistance, while the outer layer uses non-crosslinked thermoplastic polyurethane for adhesion to the molding resin, thus resolving the contradiction.
Solution Approach 2:
The insulation is constructed as a composite structure with two different resin materials. The crosslinked polyethylene inner layer provides thermal stability, while the thermoplastic polyurethane outer layer provides bonding capability. This composite approach allows both heat resistance and air tightness to be achieved simultaneously.
3Temperature
If commonly-used crosslinked polyethylene resin is used for the insulation to achieve heat resistance, then heat resistance is improved, but adhesion between the insulation and the molding resin is weak leading to poor air tightness
Solution Approach 1:
The patent adds an outer layer of thermoplastic polyurethane around the crosslinked polyethylene inner layer. This segmentation allows the inner layer to maintain heat resistance while the outer layer provides the necessary adhesion to the molding resin for air tightness.
Solution Approach 2:
The patent creates a composite insulation structure combining crosslinked polyethylene and thermoplastic polyurethane. The crosslinked polyethylene core provides thermal resistance, while the thermoplastic polyurethane shell provides bonding capability, thus achieving both heat resistance and air tightness through material composition.
4Reliability
If the insulation material has strong adhesion to achieve air tightness, then air tightness is improved, but peel-off work at the time of processing cable terminals becomes difficult
Solution Approach 1:
The patent divides the insulation into an inner layer with low adhesion (crosslinked polyethylene) and an outer layer with high adhesion (thermoplastic polyurethane). During terminal processing, the high adhesion of the outer layer ensures air tightness, while the low adhesion inner layer allows easy peeling at the conductor interface for terminal fabrication.
Solution Approach 2:
Different adhesion properties are assigned to different regions: the outer surface has high adhesion for air tightness, while the inner surface near the conductor has low adhesion for easy terminal processing. This local differentiation resolves the contradiction between air tightness and terminal processability.
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 solution achieves improved ease of handling, terminal processability, air tightness, and mechanical strength, meeting the requirements for heat resistance and tensile elongation in molded wires and cables.
Implementation Method 1
adhesion between the insulation and the molding resin is weak. Thus, sufficient air tightness cannot be achieved
Implementation Method 2
The resin molded body is fused to the insulation outer layer
Data Source
AI summary
A molded cable comprises a conductor, an insulation inner layer, an insulation outer layer, and a resin molded body. The insulation inner layer comprises a crosslinked ethylene resin composition and is provided an outer circumference of the conductor. The insulation outer layer comprises a crosslinked thermoplastic polyurethane composition and is provided on an outer circumference of the insulation inner layer. Arithmetic average roughness (Ra) of a surface of the insulation outer layer is 5μm to 100 μm. The resin molded body coats an exposed end portion of the conductor and an end portion of the insulation outer layer at a side of the exposed end portion of the conductor. The resin molded body is fused to the insulation outer layer.