Fluoropolymer Composition for Smooth Wire Coating and Low Permeation

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Solution Overview

Problem

Existing fluororesins used in coated electric wires and injection molded articles face challenges in maintaining high glass transition temperatures, surface smoothness, and resistance to corrosion and electrolytic solution permeation, while also requiring high productivity and minimal defects in the coating layer.

Innovation Solution

A copolymer composed of tetrafluoroethylene and perfluoro(propyl vinyl ether) units, with specific content ratios and melt flow rates, is developed to enhance glass transition temperature, reduce defects, and improve electrolytic solution and water vapor resistance, while minimizing mold corrosion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If the content of perfluoro(propyl vinyl ether) units is increased to improve glass transition temperature, then the glass transition temperature increases, but the melt flow rate decreases and productivity deteriorates

Engineering Contradiction:

Improveglass transition temperatureVSAvoidproductivity

Core Design Contradiction:

TemperatureVSProductivity

Solution Approach 1:

The patent optimizes the content of perfluoro(propyl vinyl ether) units to a specific range (2.8-3.5% by mass) to achieve the desired glass transition temperature while maintaining acceptable melt flow rate and productivity. This parameter optimization resolves the contradiction by finding the optimal balance point.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If the melt flow rate is increased to improve productivity, then productivity increases, but the surface smoothness of injection molded articles deteriorates

Engineering Contradiction:

ImproveproductivityVSAvoidsurface smoothness

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent specifies a controlled melt flow rate range (31-38 g/10 min) achieved through optimizing the copolymer composition. This parameter control ensures that productivity is maintained at acceptable levels while surface smoothness requirements are met.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If functional groups are present in the copolymer to improve adhesion and chemical reactivity, then chemical reactivity improves, but corrosion of metal molds and core wires increases

Engineering Contradiction:

ImproveadhesionVSAvoidcorrosion

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent limits the total number of functional groups to 50 or less per 10^6 monomer units, thereby reducing corrosion of metal molds and core wires while maintaining sufficient adhesion and chemical reactivity for practical applications.

Inventive Principle:

Principle #35Parameter changes

4Temperature

If the copolymer composition is optimized for high glass transition temperature, then glass transition temperature increases, but electrolytic solution permeability increases and sealability deteriorates

Engineering Contradiction:

Improveglass transition temperatureVSAvoidsealability

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The patent optimizes the content of perfluoro(propyl vinyl ether) units to a specific range (2.8-3.5% by mass) that simultaneously achieves the desired glass transition temperature while maintaining low electrolytic solution permeability and excellent sealability.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentEP4223793B1Copolymer, injection molded body, member to be compressed, and covered wire

Publication Date: 2025.11.12 DAIKIN INDUSTRIES LTD

Figure 1

AI summary

There is provided a copolymer containing tetrafluoroethylene unit and a perfluoro(propyl vinyl ether) unit, wherein the copolymer has a content of the perfluoro(propyl vinyl ether) unit of 2.8 to 3.5% by mass with respect to the whole of the monomer units, a melt flow rate of 31 to 38 g/10 min, and the number of functional groups of 50 or less per 106 main-chain carbon atoms.