Solvent-Free Polyurethane Repair for Aircraft Transparency
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Solution Overview
Problem
Existing repair methods for deep scratches and gouges on aircraft and aerospace transparencies, such as windows and canopies, are inadequate as they cannot effectively replenish the transparency surface when damage is severe, and standard polishing techniques fail to restore the surface.
Innovation Solution
A solvent-free, two-part polishable composition system comprising a resin component with a hydroxy-terminated polyol, light stabilizer, and catalyst, which cures to form a thermoset polyurethane, along with an optical grid for electromagnetic shielding, is used to repair both uncoated and coated transparencies, incorporating a release film for smooth application and removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of repair
If standard polishing techniques are used, then light scuffs and scratches can be removed, but deep scratches and gouges cannot be effectively repaired
Solution Approach 1:
The invention changes the physical and chemical parameters of the repair medium by using a two-part solvent-free composition that cures to form a thermoset polyurethane. This allows the repair material to be applied in a soft state and then cured to match the hardness and optical properties of the original transparency, enabling effective repair of deep damage that standard polishing cannot address.
Solution Approach 2:
The invention uses a composite repair system consisting of a two-part polyurethane composition (resin and hardener) that combines multiple functional properties: adhesion to the transparency substrate, UV stability, rain erosion resistance, and polishability. This composite approach allows the repair material to replenish deep surface loss while maintaining the optical and mechanical properties of the original transparency.
2Object-affected harmful factors
If clear protective coatings are applied, then protection against UV degradation and minor damage is provided, but the coatings do not replenish deeply damaged surfaces
Solution Approach 1:
The invention applies preliminary action by first cleaning and preparing the damaged surface, then applying the two-part composition which cures to form a protective layer. This preliminary restoration of the surface profile before final polishing allows deep scratches and gouges to be filled and restored, going beyond what protective coatings alone can achieve.
Solution Approach 2:
The repair composition changes parameters by being applied as a liquid or paste that flows into deep defects, then cures to form a solid, durable repair layer. The material transitions from a soft, applicatable state to a hardened, erosion-resistant state, enabling it to replenish deep surface loss while providing UV protection similar to the original transparency coating.
3Ease of manufacture
If solvent-based polishes are used, then abrasive smoothing can be achieved, but solvent residue and incomplete surface replenishment occur
Solution Approach 1:
The invention eliminates solvents by using a solvent-free two-part composition system. The material is applied in a workable state without solvents, allowing complete penetration into deep scratches and gouges. Upon curing, the material forms a durable, residue-free repair that maintains surface integrity without the drawbacks of solvent-based systems.
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 system provides a durable, solvent-free, rain erosion-resistant, and UV-stabilized repair that effectively fills scratches and gouges, maintaining the transparency's integrity and functionality, while the optical grid enhances electromagnetic shielding.
Implementation Method 1
a solvent-free resin component which, when cured, yields a thermoset polyurethane
Implementation Method 2
a light stabilizer which, provides weatherability
Implementation Method 3
incorporating an optical grid into the repair system electromagnetic shielding
Data Source
AI summary
The present invention provides a composition as well as a method for repairing deep scratches, gouges, etc. and which is particularly useful for aircraft and aerospace transparency repair. The composition is a blend of a polishable two-part, solvent-free, polyurethane coating composition for repairing the transparencies and which, after application, cures to a thermoset polyurethane. An optical grid is emplaced over the area to be repaired prior to applying the blend.