Covered Wire Insulating Covering Surface Roughness Control

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Solution Overview

Problem

Existing covered wires with zinc oxide and imidazole-based compounds for improved heat resistance often result in a rough insulating surface, which compromises water blocking properties due to inadequate contact between the insulating covering and water blocking members, and increases manufacturing difficulties due to surface roughness and debris generation.

Innovation Solution

A covered wire with an insulating covering composed of a resin mixture containing silane graft polyolefin, unmodified polyolefin, modified polyolefin with functional groups, flame retardant, cross-linking catalyst, zinc oxide, and imidazole-based compound, where the surface roughness is maintained at 4.0 μm or less, ensuring a smooth surface and improved fluidity, thereby enhancing heat resistance, appearance, and water blocking capabilities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If zinc oxide and imidazole-based compounds are added to improve heat resistance, then heat resistance is improved, but the surface of the insulating covering becomes rough

Engineering Contradiction:

Improveheat resistanceVSAvoidsurface roughness

Core Design Contradiction:

TemperatureVSManufacturing precision

Solution Approach 1:

The patent changes the chemical composition parameters of the resin mixture by specifying precise ratios of polyolefin (70-90 parts), zinc oxide (1-10 parts), and imidazole-based compound (1-10 parts), along with controlling moisture content at 500 ppm or less. These parameter adjustments maintain heat resistance while achieving smooth surface finish with Ra of 4.0 μm or less.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite resin mixture combining polyolefin base material with zinc oxide and imidazole-based compound additives. This composite formulation achieves both heat resistance improvement and smooth surface finish by optimizing the interaction between components, particularly by controlling moisture content to prevent surface roughness while maintaining the heat-resistant properties of the composite.

Inventive Principle:

Principle #40Composite materials

2Temperature

If the surface of the insulating covering is rough, then heat resistance is improved, but water blocking property is reduced due to small gaps between insulating covering and water blocking member

Engineering Contradiction:

Improveheat resistanceVSAvoidwater blocking property

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The patent adjusts the surface roughness parameter to Ra of 4.0 μm or less by controlling moisture content at 500 ppm or less in the resin mixture. This parameter change ensures areal contact between the insulating covering and water blocking member, maintaining water blocking property while preserving heat resistance through optimized composition ratios of zinc oxide and imidazole-based compound.

Inventive Principle:

Principle #35Parameter changes

3Temperature

If zinc oxide and imidazole-based compound are used to improve heat resistance, then heat resistance is improved, but manufacturing difficulty increases due to surface roughness and debris generation

Engineering Contradiction:

Improveheat resistanceVSAvoidmanufacturing difficulty

Core Design Contradiction:

TemperatureVSEase of manufacture

Solution Approach 1:

The patent optimizes manufacturing parameters by controlling moisture content at 500 ppm or less and specifying precise additive ratios (zinc oxide: 1-10 parts, imidazole-based compound: 1-10 parts per 100 parts polyolefin). These parameter changes reduce surface roughness to Ra of 4.0 μm or less, minimizing debris generation and improving ease of manufacture while maintaining heat resistance.

Inventive Principle:

Principle #35Parameter changes

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 excellent heat resistance, appearance, and water blocking properties by maintaining a smooth surface, reducing manufacturing challenges, and ensuring effective contact between the insulating covering and water blocking members, while also improving manufacturability and reducing debris generation.

Implementation Method 1

an insulating covering obtained by cross-linking a specific polyolefin-based composition

Methodology Applied

Scientific EffectCross-linking: Chemical Bonding

Implementation Method 2

zinc oxide and an imidazole-based compound as additives for improving heat resistance

Methodology Applied

Scientific EffectThermal stabilization:

Data Source

PatentUS11646128B2Covered wire and wire harness

Publication Date: 2023.05.09 SUMITOMO WIRING SYSTEMS LTD

AI summary

Provided are a covered wire and a wire harness having excellent heat resistance and an excellent appearance. Provided is a covered wire including a conductor and an insulating covering, in which the insulating covering is made of a resin composition, the resin composition includes a silane graft polyolefin, an unmodified polyolefin, a modified polyolefin having one or more functional groups selected from the group consisting of a carboxy group, an ester group, an acid anhydride group, an amino group, and an epoxy group, a flame retardant, a cross-linking catalyst, and zinc oxide and an imidazole-based compound, and the surface roughness Ra of the insulating covering is 4.0 μm or less.