Low Gloss UV-Cured Aircraft Coatings via Two-Step Curing
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Solution Overview
Problem
Military aircraft coatings face challenges with slow curing at ambient temperature, difficulty in directing UV radiation due to three-dimensional configurations, and oxygen inhibition of UV-curable coatings, which require impractical inert atmospheres for large objects.
Innovation Solution
A method involving a UV-curable coating composition of polyene, polythiol, flattening agent, and pigment applied to aircraft surfaces, cured with a two-step UV radiation exposure: a first dosage at 50 to 10,000 mJ/cm² and a second dosage of 1,000 to 1,000,000 mJ/cm², allowing for manual application and curing in air.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If UV radiation is used to cure the coating, then curing time is reduced, but the three-dimensional configuration of the aircraft makes it difficult to direct UV radiation from stationary sources to all exposed surfaces
Solution Approach 1:
The patent employs movable UV radiation sources that can be positioned and directed to different surfaces of the aircraft, transforming the static curing system into a dynamic one. This allows UV radiation to be effectively applied to complex three-dimensional surfaces that would be inaccessible to fixed sources, resolving the contradiction between reduced curing time and ease of operation.
2Manufacturing precision
If the coating is highly pigmented with flatting agent to achieve required color and low gloss, then the aesthetic requirements are met, but the pigments and flatting agent absorb radiation and prevent radiation from entering the interior regions of the coating
Solution Approach 1:
The patent employs a two-step curing process with periodic UV radiation exposure. The first exposure cures the surface, and the second exposure cures the interior regions. This periodic action allows the coating to be both highly pigmented for aesthetic requirements and properly cured throughout, resolving the contradiction between manufacturing precision and energy utilization.
3Ease of operation
If the coating is applied manually in the field, then the ease of application is improved, but the curing process becomes more complex requiring two-step UV radiation exposure
Solution Approach 1:
The patent divides the curing process into two separate steps: first curing the surface and then curing the interior regions. This segmentation allows each step to be optimized independently, maintaining ease of manual application while systematically addressing the complexity of curing thick, highly pigmented coatings on three-dimensional surfaces.
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
Achieves a low gloss finish with a 85° gloss of less than 10 on aircraft surfaces, enabling efficient field application and curing without the need for an inert atmosphere, reducing curing time and maintaining low gloss and color requirements.
Implementation Method 1
curing by exposure to UV or actinic radiation
Implementation Method 2
the coating composition is highly pigmented and contains a flatting agent both of which can absorb radiation and/or prevent the radiation from entering the interior regions of the coating
Data Source
AI summary
A method of applying a low gloss coating to a substrate such as the exterior surface of an aircraft is disclosed. The coating composition comprising a polyene, a polythiol, a flatting agent and a coloring pigment is applied to the substrate and given a first dosage of UV radiation followed by a second dosage in which the second dosage is greater than the first resulting in an ultralow gloss coating.