TPU Insulated Wire Surface Texture for Stronger Adhesive Bonding
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Solution Overview
Problem
Existing insulated wires with thermoplastic polyurethane insulators lack sufficient bonding strength and adhesion with adhesives, particularly in applications requiring high peel strength.
Innovation Solution
The insulated wire features a thermoplastic polyurethane outermost layer with wavy irregularities on its surface, with an arithmetic mean height of 4.4 μm to 12 μm, enhancing adhesive bonding by creating an anchor effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the insulator surface is made smooth, then the manufacturing process is simple, but the adhesion and bonding strength with adhesive are insufficient
Solution Approach 1:
The patent applies surface curvature by forming wavy irregularities on the insulator surface. These undulating patterns create a three-dimensional topography that increases surface area and provides mechanical interlocking with the adhesive, thereby enhancing peel strength without requiring complex manufacturing processes.
Solution Approach 2:
The wavy irregularities create a micro-structured surface that functions similarly to porous materials by providing increased surface area and anchoring points. The adhesive penetrates into and bonds with these wavy structures, creating a mechanically interlocked joint that resists peeling forces.
2Strength
If the surface roughness is increased to improve adhesion, then the bonding strength improves, but the manufacturing precision control becomes more difficult
Solution Approach 1:
The patent controls the arithmetic mean height (Sa) of the wavy irregularities within a specific range (3.0 μm to 15 μm). By defining this parameter range, the invention optimizes adhesion strength while maintaining manufacturability. The extrusion temperature parameter is also controlled (180°C to 220°C) to achieve the desired surface morphology.
3Strength
If the arithmetic mean height Sa is increased beyond 12 μm, then the adhesive bonding area increases, but the curing time becomes excessively long
Solution Approach 1:
The patent optimizes the arithmetic mean height Sa within the range of 3.0 μm to 15 μm, with a preferred range of 4.0 μm to 12 μm. This parameter optimization ensures sufficient adhesive bonding area while preventing excessive adhesive retention in deep valleys that would require prolonged curing times. The balance between bonding area and curing efficiency is achieved through this controlled surface topology.
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 wavy irregularities provide high peel strength and efficient adhesive bonding, ensuring reliable attachment to components like ethylene propylene rubber without prolonged curing times.
Implementation Method 1
a plurality of wavy irregularities are provided on a surface of the insulator along a direction perpendicular to a longitudinal direction of the insulated wire... providing high peel strength and efficient adhesive bonding, ensuring reliable attachment
Data Source
AI summary
An insulated wire includes a linear conductor insulative coated with an insulator made of thermoplastic polyurethane as an outermost layer, and a plurality of wavy irregularities provided on a surface of the insulator along a direction perpendicular to a longitudinal direction of the insulated wire, and an arithmetic mean height Sa of the surface of the insulator is 4.4 μm or more and 12 μm or less. A structure includes the insulated wire and a component made of ethylene propylene rubber, bonded to the surface of the insulator of the insulated wire by an adhesive.