Co-cured Polyurethane Coating on Epoxy Composites

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Solution Overview

Problem

The labor-intensive and time-consuming process of applying multiple coating layers to composite materials, which are prone to UV degradation, increases manufacturing costs and weight, and requires additional reworking steps, leading to ergonomic concerns and reduced paint adhesion.

Innovation Solution

A co-cured composite component with a polyurethane coating layer that includes a UV stabilizer and curing control agent, applied directly to the epoxy-based composite material, eliminating the need for intermediate layers and providing enhanced UV protection and chemical resistance, allowing for a single layer coating that resists chemical degradation during paint stripping.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple coating layers (primer, surfacing film, paint) are applied to composite materials, then UV protection and adhesion are improved, but manufacturing complexity, labor intensity, and time consumption increase

Engineering Contradiction:
ImproveUV protection and adhesionVSAvoidmanufacturing complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the functions of primer, surfacing film, and paint into a single co-curable coating layer. This multi-functional coating applies UV mitigation, adhesion promotion, and surface preparation properties simultaneously in one application, eliminating the need for separate layers while maintaining all necessary protective functions.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The single coating layer is designed to perform multiple functions: it provides UV blocking, promotes adhesion to the composite substrate, creates a suitable surface for subsequent paint application, and reduces the need for additional surfacing operations. This multi-functional design directly addresses the complexity issue by consolidating multiple specialized layers into one versatile coating.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Reliability

If multiple coating layers are applied to composite materials, then UV protection is improved, but weight increases

Engineering Contradiction:
ImproveUV protectionVSAvoidweight of coated structure
Core Design Contradiction:
ReliabilityVSWeight of stationary object

Solution Approach 1:

By merging multiple coating layers into a single co-curable coating, the total material quantity is reduced while maintaining UV protection functionality. This consolidation directly decreases the weight of the coated structure compared to applying separate primer, surfacing film, and paint layers.

Inventive Principle:
Principle #5Merging (Combining)

3Reliability

If intermediate coating layers are applied and then stripped during rework, then paint adhesion is improved, but labor intensity and time consumption increase

Engineering Contradiction:
Improvepaint adhesionVSAvoidlabor intensity and time consumption
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent extracts and removes the problematic intermediate surfacing film and primer layers that require stripping during rework. By using a single co-curable coating that integrates the necessary adhesion and surface preparation properties, the design eliminates the need for subsequent stripping operations while maintaining paint adhesion.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The single co-curable coating layer is designed to be a permanent, durable layer that does not require removal or stripping. Unlike traditional multi-layer systems where intermediate layers are discarded during rework, this single layer is intended to last indefinitely, eliminating the labor-intensive stripping process.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

4Reliability

If surfacing film and primer are applied separately, then adhesion and surface preparation are improved, but manufacturing time increases

Engineering Contradiction:
Improveadhesion and surface preparationVSAvoidmanufacturing time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent merges the adhesion-promoting primer layer and the surfacing film into a single co-curable coating application. This single layer simultaneously provides the bonding properties needed for paint adhesion and the surface preparation properties needed for subsequent coating, eliminating the time required for separate applications and curing cycles.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The single co-curable coating is applied in advance with all necessary adhesion and surface preparation properties already integrated. This preliminary application eliminates the need for subsequent stripping and rework operations, saving time during manufacturing and maintenance phases.

Inventive Principle:
Principle #10Preliminary action

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

This solution significantly reduces the number of processing steps, lowers production costs, and extends the life of composite materials by preventing UV degradation and chemical damage, while maintaining paint adhesion and reducing the overall weight of coated structures.

Implementation Method 1

primers and paint coatings that include a UV mitigation or a UV 'blocking' agent can be applied to a composite material surface for the purpose of protecting a composite material surface from oxidation and/or discoloration that can be caused, for example, by exposing the composite material to ultraviolet (UV) radiation

Methodology Applied
Scientific EffectUV blocking: Absorption (EM radiation)

Implementation Method 2

a co-curable paint film that is co-curable with a co-curable epoxy-based composite material... the co-curable paint film is co-cured with the co-curable epoxy-based composite material

Methodology Applied
Scientific EffectCuring: Chemical Bonding

Data Source

PatentEP3766683B1Elimination of surfacing film and primer from composite substrates through the use of a co-curable paint film
Publication Date: 2024.09.04 THE BOEING CO
  • EP3766683B1 patent drawingFigure 1~3
  • EP3766683B1 patent drawingFigure 4~5C
  • EP3766683B1 patent drawingFigure 6A~7B

AI summary

Co-curable epoxy-based composite materials (16) coated with co-curable polyurethane-based coating materials (14) to form co-curable and co-cured polyurethane coated epoxy-based composite materials, with the polyurethane-based coating materials comprising UV-stabilizer agents (12b) and cure control agents (12c) are disclosed, along with components and large structures comprising the co-cured materials.