Aqueous Primer Composition with Reactive Epoxy Coalescence
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Solution Overview
Problem
Existing aqueous primer compositions for aircraft structures face issues with stability during storage and application, poor wetting capability, and reduced chemical and corrosion resistance due to the unique wetting behavior of aqueous compositions, leading to rough and powdery coatings that are prone to chips and scratches.
Innovation Solution
Aqueous primer compositions using a reactive liquid epoxy as a coalescent agent, allowing for the formation of a continuous film without the need for organic solvents, by coalescing resin particles during drying and curing, with a curative that is water-insoluble and reactive with the resins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If organic solvent is introduced into the emulsion to coalesce resin particles, then film-forming ability is improved, but storage stability is reduced and wetting capability deteriorates
Solution Approach 1:
The patent changes the chemical nature of the coalescent from traditional organic solvents to a reactive liquid epoxy resin. This parameter change allows the coalescent to remain effective at lower concentrations while improving storage stability and maintaining wetting capability through its reactive chemistry and controlled film formation mechanism.
2Object-affected harmful factors
If aqueous composition is used as primer, then volatile organic solvent emissions are reduced, but coating uniformity and surface quality deteriorate
Solution Approach 1:
The patent creates a composite aqueous primer system combining water-based emulsion with reactive liquid epoxy resin as coalescent. This composite approach maintains the environmental benefits of aqueous formulations while achieving uniform coating quality through the synergistic interaction between the emulsion particles and the reactive coalescent that forms a continuous film during curing.
3Reliability
If high melting point thermosetting resin is used in aqueous dispersion, then corrosion resistance is improved, but film smoothness and continuity deteriorate
Solution Approach 1:
The reactive liquid epoxy resin acts as an intermediary between the high melting point thermosetting resin particles and the aqueous medium. During drying and curing, this intermediary facilitates the coalescence of rigid particles into a smooth, continuous film while maintaining the corrosion-resistant properties of the thermosetting resin network.
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 a uniform, continuous primer film with improved surface protection and high storage stability, enhancing handling and corrosion resistance.
Implementation Method 1
a second thermosetting resin that is liquid at ambient conditions and acting as a reactive coalescent agent in which the first thermosetting resin is at least partially soluble
Implementation Method 2
Aqueous primers, which use water as a volatile solvent, are provided in the form of a latex-emulsified particles of a thermosetting resin dispersed in aqueous dispersion. Typically, the dispersion is coated onto a substrate, dried, and then heated to cure the thermosetting resin.
Data Source
AI summary
Provided is an aqueous primer composition including a first thermosetting resin that is a particulate solid at ambient conditions and a second thermosetting resin that is liquid at ambient conditions and acting as a reactive coalescent agent in which the first thermosetting resin is at least partially soluble. The second thermosetting resin acts as a coalescent agent to enable a continuous primer film to be formed as the primer is being dried before it is cured. The composition further includes a curative that is substantially water-insoluble and reactive with the first and second thermosetting resins. The overall composition can contain up to 4 percent by weight of volatile solvents, other than water and provides a shelf-stable primer that can form a continuous film without the need for added organic solvents.