Polysulfide Sealant Removal Composition for Reversible Re-Curing

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Solution Overview

Problem

Existing polysulfide sealant removal techniques are time-consuming, potentially damaging to substrates, and use harsh chemicals that pose environmental and health hazards.

Innovation Solution

Compositions comprising a water-miscible organic solvent, water, and a dithiol are used to cleave disulfide crosslinks in polysulfide sealants, allowing for easier removal and subsequent re-curing, featuring a reversible process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If harsh chemicals are used to remove polysulfide sealants, then removal effectiveness is improved, but environmental and health hazards increase

Engineering Contradiction:

Improvesealant removal effectivenessVSAvoidenvironmental and health hazards

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the chemical parameters of the removal composition by using oxidizing agents (potassium permanganate, hydrogen peroxide, sodium hypochlorite) combined with alkaline substances (ammonia, sodium hydroxide, calcium hydroxide). This parameter change allows effective sealant removal through oxidation of disulfide bonds while avoiding the need for traditionally harsh chemicals, thus maintaining removal effectiveness while reducing environmental and health hazards.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent converts the harmful effect of strong oxidizing agents into a beneficial process by controlling the oxidation reaction to specifically target and break disulfide bonds in polysulfide sealants. The oxidizing agents that could potentially damage substrates are instead directed to selectively cleave the sealant's crosslinks, transforming a potentially harmful chemical process into a controlled and safe removal mechanism.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Productivity

If mechanical scraping or abrading is used to remove sealants, then removal effectiveness is improved, but substrate damage increases

Engineering Contradiction:

Improvesealant removal effectivenessVSAvoidsubstrate damage

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces mechanical removal methods (scraping, abrading) with a chemical solution-based approach. The chemical composition penetrates and softens the sealant while the oxidizing agent chemically breaks the disulfide bonds, allowing the sealant to be removed through minimal mechanical action or even self-removal, thereby eliminating the need for aggressive mechanical tools that would damage the substrate.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The chemical composition acts as an intermediary between the removal process and the substrate. The solution first penetrates and chemically modifies the sealant structure, creating a soft, degraded state that can be easily removed without direct mechanical contact with the substrate. This intermediary chemical process protects the substrate from mechanical damage while achieving effective sealant removal.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Productivity

If mechanical scraping or abrading is used to remove sealants, then removal effectiveness is improved, but time consumption increases

Engineering Contradiction:

Improvesealant removal effectivenessVSAvoidtime consumption

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

The chemical composition performs preliminary action by penetrating the sealant and chemically degrading the disulfide bond structure before actual removal is needed. The oxidizing agents initiate the breakdown process in advance, softening and decomposing the sealant matrix so that subsequent removal requires minimal time and effort, whereas mechanical methods would require continuous scraping and abrading operations.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The chemical removal process provides continuous useful action as the oxidizing agents continuously break disulfide bonds and the alkaline components continuously soften the sealant matrix during the treatment time. This continuous chemical degradation progresses the removal process simultaneously, eliminating the need for intermittent mechanical intervention and reducing total time consumption compared to manual scraping operations.

Inventive Principle:

Principle #20Continuity of useful 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

The compositions enable safe, efficient, and environmentally friendly removal of polysulfide sealants with the ability to re-cure, minimizing substrate damage and environmental impact.

Implementation Method 1

The dithiol is capable of cleaving the disulfide crosslinks in the polysulfide sealant

Methodology Applied

Scientific EffectThiol-disulfide exchange reaction: Chemical Bonding

Data Source

PatentEP3851497B1Compositions for use with polysulfide sealants and related methods

Publication Date: 2026.03.04 THE BOEING CO

AI summary

Compositions for modifying a degree of cure in a polysulfide sealant are provided. In embodiments, the composition comprises a water-miscible organic solvent; water; and a dithiol. Polysulfide sealant systems comprising the compositions are also provided. Methods for modifying a degree of cure in a polysulfide sealant using the compositions are also provided.