UV-Curable Curing Material for Wire Harness Waterproofing
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Solution Overview
Problem
UV-curable curing materials used for waterproofing wire harnesses face issues due to the need for high-temperature melting and plasticizer migration from polyvinyl chloride resin, leading to reduced adhesive strength and insufficient waterproofing, especially in areas where UV radiation does not reach.
Innovation Solution
A curing material containing a chain transfer agent with a polyether structure and metal-containing compounds, having a solubility parameter of 9.4 or more, which inhibits plasticizer migration and allows for UV-independent curing, using a photo-curing material that can cure at room temperature and is applied with a light-transmissive protective member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a photo-curing resin is used for waterproofing wire harnesses, then the curing time is shortened and the process is simplified, but the resin remains uncured in areas where UV radiation does not reach, resulting in insufficient waterproofing performance
Solution Approach 1:
The patent divides the curing mechanism into two segments: UV-initiated photopolymerization for surface and accessible areas, and thermal polymerization for enclosed areas where UV light cannot reach. This segmentation allows each curing mechanism to operate in its optimal zone, ensuring complete curing throughout the waterproofing material.
Solution Approach 2:
The patent merges two different curing mechanisms (UV photopolymerization and thermal polymerization) into a single dual-cure system. The waterproofing resin contains both photopolymerization initiators and thermal polymerization catalysts, allowing it to be cured by either or both methods depending on the application scenario.
2Strength
If the curing material is applied to polyvinyl chloride resin, then the adhesive bonding is improved, but the plasticizer migrates to the curing material, causing a reduction in adhesive strength
Solution Approach 1:
The patent introduces a compatibility controller as an intermediary substance that mediates between the plasticizer in the polyvinyl chloride resin and the curing material. This compatibility controller prevents direct harmful interactions between the plasticizer and curing material, thereby inhibiting plasticizer migration while maintaining adhesive bonding.
Solution Approach 2:
The patent modifies the chemical parameters of the curing material system by adding a compatibility controller, which changes the solubility parameters and chemical affinity between the curing material and plasticizer. This parameter change reduces the thermodynamic driving force for plasticizer migration into the curing material.
3Ease of operation
If a hot-melt adhesive is used, then the adhesive can be applied at high temperature, but the adhesive needs to be melted at high temperature at the time of use, which is inconvenient
Solution Approach 1:
The patent replaces the thermal melting mechanism with a photochemical or catalytic curing mechanism. Instead of requiring high-temperature melting for application, the curing material can be applied at room temperature and then cured through UV irradiation or thermal catalysis, eliminating the need for high-temperature handling.
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 effectively prevents plasticizer migration and achieves good waterproofing performance by curing in areas without UV exposure, maintaining adhesive strength and ensuring long-term physical properties of the wire harness.
Implementation Method 1
an ultraviolet curing resin is often used as the waterproofing resin because of its short curing time and ease of the process
Implementation Method 2
a curing material containing at least a chain transfer agent, wherein the chain transfer agent contains a compound (a) containing a polyether structure and two or more urethane bonds or two or more urea bonds in a molecule
Implementation Method 3
the curing material has a solubility parameter of 9.4 or more, and, when the curing material is used in an application in which the curing material is in contact with a resin containing a plasticizer, the plasticizer can be inhibited from migrating to the curing material
Data Source
AI summary
A curing material, having a solubility parameter of 9.4 or more, contains at least a chain transfer agent that contains a compound containing a polyether structure and two or more urethane bonds or two or more urea bonds in a molecule, and a metal-containing compound. A wire harness is manufactured by supplying the curing material to a conductor exposed portion of a wire bundle including a plurality of bundled insulated wires each having a conductor covered with a covering material made of an insulating body, the conductor exposed portion being formed by removing a part of the covering material of the wire bundle to expose the conductor inside; and curing the curing material by irradiating light in a state in which a surface of the curing material is covered with a protective member formed from a resin containing a plasticizer and having light transmissivity, thereby forming a waterproof portion.