Acrylate Adhesive Stabilization Against Thermal Cohesive Strength Rise

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Solution Overview

Problem

Conventional pressure-sensitive adhesives based on (meth)acrylate polymers exhibit increased cohesive strength at elevated temperatures due to crosslinking reactions, which can lead to reduced flexibility and usability in applications requiring bendability, foldability, or rollability.

Innovation Solution

Incorporating a high temperature stabilization agent such as hydrotalcite or carbodiimide into the (meth)acrylate polymeric or copolymeric matrix to suppress the rise in cohesive strength, maintaining optical transparency and flexibility even at elevated temperatures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If (meth)acrylate pressure sensitive adhesives are used, then optical transparency is achieved, but cohesive strength increases at elevated temperatures due to crosslinking reactions

Engineering Contradiction:

Improveoptical transparencyVSAvoidcohesive strength

Core Design Contradiction:

Illumination intensityVSStrength

Solution Approach 1:

A silane compound is introduced as an intermediary substance that reacts with hydroxyl groups on polymer chains to form crosslinks. This mediator enables controlled crosslinking that maintains optical transparency while managing cohesive strength development at elevated temperatures, resolving the contradiction between transparency and strength stability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention changes the chemical parameters of the adhesive system by incorporating specific silane compounds and controlling their reaction with hydroxyl groups. This parameter change allows the adhesive to maintain stable cohesive strength at elevated temperatures while preserving optical transparency, addressing the temperature-strength contradiction.

Inventive Principle:

Principle #35Parameter changes

2Strength

If crosslinking reactions occur at elevated temperatures, then cohesive strength increases, but flexibility and bendability are reduced

Engineering Contradiction:

Improvecohesive strengthVSAvoidflexibility

Core Design Contradiction:

StrengthVSEase of operation

Solution Approach 1:

The silane compound acts as a mediator that creates crosslinks between polymer chains in a controlled manner. This intermediary approach allows the adhesive to maintain appropriate flexibility for bending and folding operations while developing sufficient cohesive strength, resolving the contradiction between strength and flexibility.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Stability of the object's composition

If high temperature stabilization is achieved through crosslinking, then cohesive strength stability improves, but optical transparency may be compromised

Engineering Contradiction:

Improvecohesive strength stabilityVSAvoidoptical transparency

Core Design Contradiction:

Stability of the object's compositionVSIllumination intensity

Solution Approach 1:

The silane compound serves as a transparent intermediary that forms crosslinks without compromising optical properties. This mediator enables high temperature stabilization through controlled crosslinking while maintaining optical transparency, resolving the contradiction between stability and transparency.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

By changing the chemical composition to include specific silane compounds and controlling their reaction parameters, the invention achieves both high temperature stability and optical transparency simultaneously, overcoming the contradiction between these two properties.

Inventive Principle:

Principle #35Parameter changes

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 addition of hydrotalcite or carbodiimide effectively stabilizes the adhesive's cohesive strength, ensuring it remains low after exposure to temperatures of at least 85°C for 7 days, as measured by stress relaxation, while maintaining optical transparency and clarity.

Implementation Method 1

Conventional pressure-sensitive adhesives based on (meth)acrylate polymers exhibit increased cohesive strength at elevated temperatures due to crosslinking reactions

Methodology Applied

Scientific EffectCrosslinking reactions: Chemical Bonding

Implementation Method 2

The pressure sensitive adhesive composition is optically transparent

Methodology Applied

Scientific EffectOptical transparency:

Implementation Method 3

the increase of cohesive strength as measured by stress relaxation is 0.1 or less

Methodology Applied

Scientific EffectStress relaxation: Stress Relaxation

Data Source

PatentUS20230416572A1High temperature stable optically transparent pressure sensitive adhesives

Publication Date: 2023.12.28 3M INNOVATIVE PROPERTIES CO

AI summary

High temperature stable optically transparent pressure sensitive adhesives include a (meth)acrylate polymeric or copolymeric matrix and at least one high temperature stabilization agent. The (meth)acrylate polymeric or copolymeric matrix is the reaction product of at least one (meth)acrylate monomer having at least one hydroxyl group. The pressure sensitive adhesive composition, upon exposure to a temperature of at least 85° C. for 7 days, has an increase of cohesive strength as measured by stress relaxation of 0.1 or less.