Flexible Non-Chromate Primer for Aerospace Coatings
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Solution Overview
Problem
Epoxy-based thermosetting primers in aerospace applications are unacceptably hard and brittle, and there is a need for non-chromate primer coatings that combine the adhesion of thermosetting epoxy systems with the flexibility of polyurethane coatings.
Innovation Solution
A coating composition comprising a thiol-terminated urethane-containing polyether prepolymer, a polyepoxide, calcium carbonate, and magnesium oxide, which provides a primer system that can be cured and used in a multilayer coating system with a polyurethane topcoat, offering improved corrosion resistance and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If epoxy-based thermosetting primers are used, then corrosion resistance and adhesion are improved, but the coating becomes hard and brittle
Solution Approach 1:
The patent combines polyether polyol (providing flexibility) with epoxy resin (providing adhesion and corrosion resistance) to create a composite primer coating that simultaneously achieves both flexibility and corrosion resistance, resolving the contradiction between these two properties
Solution Approach 2:
The patent modifies the chemical composition parameters of the primer by incorporating polyether polyol with specific molecular weight and flexibility characteristics, changing the physical and chemical properties of the coating to achieve the desired balance between flexibility and corrosion resistance
2Reliability
If chromate and heavy metals are used in primer coatings, then corrosion resistance and adhesion are improved, but safety hazards increase
Solution Approach 1:
The patent removes chromate and heavy metal components from the primer formulation, extracting the harmful elements while maintaining corrosion resistance through alternative mechanisms based on polyether polyol and epoxy resin chemistry
Solution Approach 2:
The patent replaces expensive and hazardous chromate corrosion inhibitors with safer, more environmentally friendly alternative materials that achieve similar corrosion protection without the associated safety and environmental risks
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 composition achieves a balance of adhesion and flexibility, enhancing corrosion resistance and solvent resistance, such as Skydrol resistance, while being free from chromium-containing materials, making it suitable for aerospace applications.
Implementation Method 1
a thiol-terminated urethane-containing polyether prepolymer; a polyepoxide
Implementation Method 2
magnesium oxide and calcium carbonate
Implementation Method 3
magnesium oxide and calcium carbonate
Data Source
AI summary
Primer coating compositions include a thiol-terminated urethane-containing polyether prepolymer, a polyepoxide, calcium carbonate, and magnesium oxide. The coating compositions are useful as corrosion resistant primers in aerospace applications.