Conductive Protective Liner for Aircraft Canopy Durability

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Solution Overview

Problem

Current electrically conductive coating stacks for aircraft canopies suffer from poor durability due to delamination and corrosion, leading to limited service life and inadequate static drain, despite providing infrared reflection and radar attenuation.

Innovation Solution

A protective liner comprising a polymeric base layer, a conductive polymeric interlayer, and a conductive top layer with reactive organic salt is applied to enhance the multilayer stack, improving static dissipation and corrosion resistance, and including a quaternary ammonium chloride for anti-static properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a metal conductive layer is used in the multilayer stack, then electrical conductivity and static dissipation are improved, but corrosion resistance and durability deteriorate due to oxidation and moisture penetration

Engineering Contradiction:
Improveelectrical conductivityVSAvoidservice life
Core Design Contradiction:
ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent uses a composite structure combining organic conductive polymers (PEDOT:PSS) with inorganic metal layers (silver and ITO). This composite approach maintains electrical conductivity while the polymer matrix provides corrosion resistance and protects the metal from oxidation, resolving the contradiction between conductivity and durability

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The conductive polymer layer acts as an intermediary between the metal conductive layer and the environment. It provides a protective barrier that prevents direct contact between moisture/oxygen and the metal layers, thereby maintaining electrical conductivity while preventing corrosion and extending service life

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If multiple layers are added to improve conductivity and protection, then functional performance is improved, but manufacturing complexity increases

Engineering Contradiction:
Improvestatic dissipationVSAvoidmanufacturing complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines multiple functions into integrated layers. The conductive polymer layer simultaneously provides conductivity, corrosion protection, and structural integrity. The top coat layer integrates UV protection, abrasion resistance, and additional corrosion protection in a single layer, reducing the number of separate manufacturing steps

Inventive Principle:
Principle #5Merging (Combining)

3Temperature

If the top coat is made durable to withstand extreme temperatures, then thermal resistance is improved, but moisture penetration and corrosion increase

Engineering Contradiction:
Improvethermal resistanceVSAvoidmoisture penetration
Core Design Contradiction:
TemperatureVSObject-affected harmful factors

Solution Approach 1:

The patent applies different material properties to different layers based on their specific functions. The top coat uses aliphatic polyurethane optimized for thermal resistance and UV protection, while the conductive polymer layer provides moisture barrier properties. This localized optimization allows each layer to excel at its specific function without compromising overall performance

Inventive Principle:
Principle #3Local quality

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 enhanced multilayer stack exhibits improved durability, static dissipation, and resistance to corrosion and abrasion, extending the service life of aircraft canopies and maintaining electromagnetic pulse protection.

Implementation Method 1

The conductive top layer provides additional anti-static properties

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 2

The conductive polymeric interlayer generally has suitable surface resistance that facilitates the dissipation of static charge

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 3

the metal conductive layer 40 provides for electromagnetic interference (EMI) shielding and radar attenuation

Methodology Applied
Scientific EffectElectromagnetic shielding: Faraday Cage

Implementation Method 4

helps dissipate static charge that can develop during flight and/or from lightning strikes

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 5

The metal conductive layer 40 can be heated for de-fogging, de-misting, defrosting, or deicing

Methodology Applied
Scientific EffectThermal heating: Heating

Implementation Method 6

The substrate base layer 20 provides adhesion between the metal conductive layer 40 and an aircraft canopy substrate 10

Methodology Applied
Scientific EffectAdhesion: Adhesive

Data Source

PatentEP2349943B1Electrically conductive protective liner
Publication Date: 2018.10.17 PPG INDUSTRIES OHIO INC
  • EP2349943B1 patent drawingFigure 1~3
  • EP2349943B1 patent drawingFigure 4~8

AI summary

A protective liner includes a base layer that can be affixed to an aircraft canopy or other substrate, a conductive polymeric interlayer positioned over the base layer, and a conductive top layer containing a reactive organic salt, or a hygroscopic salt, positioned over the conductive polymeric interlayer. The substrate can also be treated with a multilayer stack (including a substrate base coat layer, a metal layer positioned over the substrate base layer, a metal oxide layer positioned over the metal layer, and a tie layer positioned over the metal oxide layer). The protective liner can be affixed to a pretreated substrate by lamination or other means to form an enhanced, multilayer stack having beneficial properties.