ETFE Primer Composition Adhesion and Flowability
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Solution Overview
Problem
Current ETFE coating films face challenges with adhesion properties to substrates, as existing primer compositions either do not provide sufficient adhesion or require high epoxy resin content, leading to decreased flowability and uneven coating film thickness, and are prone to foaming or swelling due to heat decomposition during the curing process.
Innovation Solution
A powder primer composition comprising reactive ethylene/tetrafluoroethylene copolymer with specific monomer units and an epoxy resin, optimized in terms of molar ratios and particle sizes, which forms a primer layer that enhances adhesion to substrates and fluororesin top coatings, while maintaining flowability and storage stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a high content of epoxy resin (at least 30%) is added to fluororesin powder to improve adhesion properties, then adhesion properties are improved, but flowability of the powder decreases and thickness of the coating film becomes uneven
Solution Approach 1:
The invention changes the chemical structure parameters of the ETFE copolymer by introducing specific functional groups (carboxyl, hydroxyl, or amine groups) at controlled concentrations (0.1-5 mmol/g). This allows the polymer to achieve adequate adhesion through chemical functionality rather than relying on high epoxy resin content, thus maintaining powder flowability while improving adhesion properties.
Solution Approach 2:
The invention creates a composite powder system combining modified ETFE copolymer particles with specific functional groups. This composite structure integrates the adhesive functionality directly into the fluororesin matrix, eliminating the need for separate high-content epoxy resin additions and their associated flowability problems.
2Strength
If conventional primer compositions are used to improve adhesion properties, then adhesion is enhanced, but foaming or swelling occurs due to heat decomposition of the curing agent or epoxy resin in the firing step
Solution Approach 1:
The invention extracts and eliminates the problematic components (separate curing agents and high epoxy resin content) from the primer composition. Instead, it uses ETFE copolymer with built-in functional groups that provide adhesion without requiring additional curing agents that decompose during firing, thus preventing foaming and swelling.
Solution Approach 2:
The invention converts the inherent chemical reactivity of ETFE copolymer (which can lead to instability) into a benefit by carefully controlling the introduction of functional groups. This controlled reactivity provides adhesion enhancement while avoiding the harmful decomposition effects seen in conventional systems with high epoxy resin and curing agent content.
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 provides excellent adhesion properties to both substrates and top coating layers, ensuring uniformity and durability of the coating film, while preventing foaming and swelling during the curing process, thus improving the overall performance of ETFE-coated materials.
Implementation Method 1
a powder made of a reactive ethylene/tetrafluoroethylene copolymer containing repeating units (A) based on tetrafluoroethylene, repeating units (B) based on ethylene, and repeating units (C) based on a monomer having an acid anhydride residue and a polymerizable unsaturated bond
Implementation Method 2
a powder made of an epoxy resin having an epoxy equivalent of from 500 to 2,700 and a softening point of at least 70°C
Implementation Method 3
coating by an electrostatic coating method is widely used, since it is thereby possible to easily form a coating film on the surface of an abnormally shaped article
Data Source
AI summary
To provide a powder primer composition excellent in adhesion properties and a laminate obtained by using it. The power primer composition comprises a powder made of a reactive ethylene/tetrafluoroethylene copolymer containing repeating units (A) based on tetrafluoroethylene, repeating units (B) based on ethylene, and repeating units (C) based on a monomer having an acid anhydride residue and a polymerizable unsaturated bond, wherein (C)/((A) + (B)) is from 1/10,000 to 5/100 by molar ratio; and a powder made of an epoxy resin having an epoxy equivalent of from 500 to 2,700 and a softening point of at least 70°C; wherein the mass ratio of the powder made of a reactive ethylene/tetrafluoroethylene copolymer to the powder made of an epoxy resin is from 99/1 to 80/20.