Expandable Epoxy Adhesive Composition for Large Gap Curing Heat Control

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Solution Overview

Problem

Existing thermally expandable structural epoxy adhesives face limitations in large gap applications due to high peak core temperatures during ring-opening polymerization, leading to thermal degradation.

Innovation Solution

Incorporation of thermally conductive fillers, such as aluminum oxides and boron nitride, into the adhesive composition to reduce peak core temperatures during curing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If thermally expandable structural epoxy adhesives are used for automotive metal bonding, then superior strength, water absorption characteristics and metal adhesion are achieved, but large amount of heat is released during ring-opening polymerization leading to peak core temperatures above cure temperature and thermal degradation

Engineering Contradiction:

Improveadhesive strengthVSAvoidpeak core temperature

Core Design Contradiction:

StrengthVSTemperature

Solution Approach 1:

The patent introduces a heat transfer promoter (thermally conductive filler) as an intermediary substance within the adhesive composition. This promoter facilitates the transfer of heat from the exothermic polymerization reaction to the surrounding adhesive material and substrates, preventing localized overheating and reducing peak core temperatures while maintaining the structural integrity and strength of the cured adhesive.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent creates a composite adhesive material by combining epoxy resin with thermally conductive fillers (such as metal powders, oxides, or nitrides). This composite structure allows the adhesive to simultaneously achieve high strength through epoxy polymerization and effective heat dissipation through the thermally conductive filler network, resolving the contradiction between strength and temperature control.

Inventive Principle:

Principle #40Composite materials

2Adaptability or versatility

If expandable structural epoxy adhesives are used in large gap applications, then cavity sealing and reinforcement are achieved, but thermal degradation occurs due to excessive peak core temperatures

Engineering Contradiction:

Improvelarge gap application capabilityVSAvoidadhesive reliability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The heat transfer promoter acts as an intermediary that mediates between the exothermic polymerization reaction and the surrounding environment. By introducing this thermal management component, the adhesive can reliably fill large gaps and reinforce cavities without suffering from thermal degradation, thus maintaining reliability while expanding adaptability to large gap applications.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent modifies the thermal parameters of the adhesive system by incorporating thermally conductive fillers. This changes the heat transfer characteristics of the adhesive, allowing it to dissipate the heat generated during curing more effectively. As a result, the adhesive can be used in large gap applications with improved reliability, as the modified thermal parameters prevent the excessive temperature rise that would otherwise cause degradation.

Inventive Principle:

Principle #35Parameter changes

3Temperature

If thermally conductive fillers are incorporated into the adhesive composition, then peak core temperatures are reduced enabling large gap applications, but adhesive composition complexity increases

Engineering Contradiction:

Improvepeak core temperatureVSAvoidadhesive composition complexity

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The patent applies parameter changes by modifying the thermal conductivity parameter of the adhesive through filler incorporation. This single parameter change (increasing thermal conductivity) achieves the desired temperature reduction with relatively simple implementation, avoiding the need for complex multi-component systems or sophisticated heat management architectures.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

While incorporating thermally conductive fillers does increase composition complexity, the patent uses well-established composite material approaches with common fillers (metal powders, oxides, nitrides) that are readily available and easy to process. This keeps the practical complexity manageable while achieving the thermal management benefits.

Inventive Principle:

Principle #40Composite materials

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 use of thermally conductive fillers results in reduced peak core temperatures, enabling the adhesive to be used in large gap applications and facilitating automated assembly processes.

Implementation Method 1

Incorporation of thermally conductive fillers, such as aluminum oxides and boron nitride, into the adhesive composition to reduce peak core temperatures during curing

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)