Hydrophobic Polyimide Foam Surface Treatment

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Solution Overview

Problem

Untreated open cell polyimide foams are oleophilic and hydrophilic, allowing water and oils to easily ingress, necessitating a method to impart oil and water repellency (OWR) properties to reduce liquid absorption and retention, especially in applications requiring thermal and acoustic insulation.

Innovation Solution

A chemical treatment method is applied to the open cell polyimide foam, using treatment chemicals such as perfluoroacrylates and polysiloxanes, which are bonded to the interior surface to render the foam hydrophobic or oleophobic, maintaining the foam's insulation properties and stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If open cell polyimide foam is used for thermal and acoustic insulation, then insulation performance is improved, but liquid absorption increases due to oleophilic and hydrophilic nature

Engineering Contradiction:

Improveinsulation performanceVSAvoidliquid absorption

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent applies local quality by treating only the surface of the foam with hydrophobic/oleophobic chemicals rather than changing the bulk properties. The treatment creates a surface layer with different properties (liquid-repellent) while maintaining the interior open cell structure for insulation. This resolves the contradiction by making the surface locally resistant to liquids while preserving the bulk insulation performance.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent creates a composite structure by combining the polyimide foam substrate with hydrophobic/oleophobic treatment chemicals on the surface. This composite approach allows the foam to maintain its insulation properties while gaining liquid repellency from the treatment layer, effectively resolving the contradiction between insulation performance and liquid absorption.

Inventive Principle:

Principle #40Composite materials

2Quantity of substance

If chemical treatment is applied to impart water and oil repellency, then liquid absorption is reduced, but manufacturing complexity increases

Engineering Contradiction:

Improveliquid absorptionVSAvoidmanufacturing process

Core Design Contradiction:

Quantity of substanceVSDevice complexity

Solution Approach 1:

The patent utilizes the porous open cell structure of the foam to enable simple absorption of the hydrophobic/oleophobic treatment chemicals. The porous nature allows the chemicals to penetrate and coat the internal surfaces easily through capillary action, simplifying the manufacturing process while effectively reducing liquid absorption.

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The treatment process leverages the foam's own porous structure to absorb and distribute the treatment chemicals uniformly throughout the material. The foam essentially treats itself by absorbing the chemicals into its open cell structure, reducing the need for complex application equipment or multiple processing steps.

Inventive Principle:

Principle #25Self-service

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 treated polyimide foam effectively repels water and oils, maintaining thermal and acoustic insulation performance while reducing liquid absorption, as demonstrated by hot/wet testing and fire resistance protocols, with minimal impact on the foam's original properties.

Implementation Method 1

The treatment chemical has a property of repelling water or oil... The treatment chemical renders the interior surface hydrophobic or oleophobic

Methodology Applied

Scientific EffectHydrophobic effect: Hydrophobe

Implementation Method 2

The treatment chemical has a property of repelling water or oil... The treatment chemical renders the interior surface hydrophobic or oleophobic

Methodology Applied

Scientific EffectOleophobic effect: Hydrophobe

Data Source

PatentUS8324285B2Hydrophobic and/or oleophobic open cell polyimide acoustic and thermal insulation foams and methods of making

Publication Date: 2012.12.04 THE BOEING CO

AI summary

Provided are methods of treating an open cell polyimide foam product to produce a treated polyimide foam product having a property of repelling water or oil. The method includes the steps of: selecting a polyimide foam product having an external surface area and an open cell structure that has an interior surface area, wetting the exterior surface area and the interior surface area with a chemical treatment fluid comprising a treatment chemical that has a property of repelling water or oil, and distributing the treatment chemical onto at least a portion of the interior surface area sufficient to modify a surface property of the interior surface. Also provided are treated polyimide foam products that have an open cell polyimide foam substrate with an interior surface area and a treatment chemical on at least a portion of the interior surface area. The treatment chemical renders the interior surface hydrophobic or oleophobic.