Fluoroelastomer Wire Overmolding for Airtight Adhesion
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Solution Overview
Problem
The weak adhesion between fluorine-containing elastomer compositions and molding materials, such as polyamide or polyurethane resins, hinders the achievement of desired airtightness in electric wires and cables, especially when cross-linked fluorine-containing elastomers are used, which complicates the downsizing and cost reduction of molded articles.
Innovation Solution
An insulated wire or cable with an outermost layer comprising a resin composition of fluorine-containing elastomer, including a tetrafluoroethylene-propylene copolymer and ethylene-tetrafluoroethylene copolymer, with a specific mass ratio and inorganic fillers like calcium carbonate or silica, which is cross-linked and treated with atmospheric-pressure plasma to enhance adhesion to molding materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a heat-shrinkable tube is provided between the electric wire/cable and the molding material to obtain airtightness, then the airtightness is improved, but the number of components increases
Solution Approach 1:
The patent combines the heat-shrinkable tube function with the fluorine-containing elastomer covering material itself, making the covering material serve dual purposes: providing heat resistance and acting as the airtight sealing layer. This eliminates the need for a separate heat-shrinkable tube component while achieving the desired airtightness between the molding material and wire/cable.
Solution Approach 2:
The fluorine-containing elastomer composition is designed to perform multiple functions simultaneously: it provides heat resistance, mechanical protection, and airtight sealing. By enhancing its adhesion properties through specific compositional ratios and surface treatment, it becomes a universal solution that replaces both the original covering material and the heat-shrinkable tube.
2Temperature
If cross-linked fluorine-containing elastomer composition is used to improve heat resistance, then the heat resistance is improved, but the adhesion to molding material deteriorates
Solution Approach 1:
The patent modifies the chemical composition parameters of the fluorine-containing elastomer by controlling the ratio of tetrafluoroethylene-propylene copolymer to ethylene-tetrafluoroethylene copolymer (within 100:0 to 60:40 mass ratio) and adding specific inorganic fillers (5-60 parts by mass of calcium carbonate and/or silica per 100 parts by mass of base polymer). These parameter changes maintain heat resistance while improving adhesion to molding materials.
Solution Approach 2:
The patent replaces mechanical adhesion methods (such as physical anchoring effects) with chemical adhesion mechanisms. By introducing functional groups through plasma treatment and optimizing the chemical composition, the elastomer forms chemical bonds with the molding material, providing superior adhesion that is not dependent on mechanical interlocking.
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
This configuration improves the adhesion of the fluorine-containing elastomer to molding materials, ensuring airtightness while maintaining heat resistance and reducing the number of components, thus enabling cost-effective and compact molded articles.
Implementation Method 1
the outermost layer is treated by atmospheric-pressure plasma
Data Source
AI summary
A method for producing a molding article includes preparing an insulated wire including an outermost layer disposed on an outer periphery of a conductor, the outermost layer including a resin composition including a fluorine-containing elastomer. The resin composition includes a tetrafluoroethylene-propylene copolymer and an ethylene-tetrafluoroethylene copolymer as an entire base polymer or a portion of the base polymer at a mass ratio of the tetrafluoroethylene-propylene copolymer to the ethylene-tetrafluoroethylene copolymer in a range of 100:0 to 60:40. The resin composition further includes 5 to 60 parts by mass of calcium carbonate and/or silica as an inorganic filler with respect to 100 parts by mass of the base polymer.