Polyurethane Adhesive Drop Resistance

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Pressure-sensitive adhesives used in electronic devices, particularly for bonding cover glass to device frames, face challenges in maintaining adhesion under normal conditions, deformation, and traumatic forces such as drops, requiring a combination of drop resistance, anti-lifting properties, and chemical resistance.

Innovation Solution

A polyurethane adhesive composition formed from an aliphatic polyisocyanate, a polyol component with specific solubility parameters and hydrogen bonding, and a functional acid containing compound, which includes aromatic and aliphatic polyester, polycaprolactone, or polycarbonate polyols, providing a rare combination of drop resistance and anti-lifting performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional acrylic or polyurethane adhesives are used for bonding cover glass to device frames, then adhesion is provided under normal conditions, but the adhesive fails to maintain bonding under traumatic forces such as drops

Engineering Contradiction:

Improvedrop resistanceVSAvoidadhesive bond strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent modifies the chemical composition parameters of the polyurethane adhesive by incorporating specific polyols (polyester, polycaprolactone, or polycarbonate) with controlled molecular weights and functional groups. This changes the adhesive's physical and chemical properties to achieve both high bond strength and drop resistance, resolving the contradiction between maintaining strong adhesion and withstanding traumatic forces.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite polyurethane adhesive system combining multiple components: polyol, polyisocyanate, and functional acid containing compound. This composite approach allows the adhesive to simultaneously achieve strong bonding capability and impact resistance, addressing both requirements without compromise.

Inventive Principle:

Principle #40Composite materials

2Strength

If adhesive formulation is optimized for high bond strength, then adhesion under normal conditions is maintained, but chemical resistance deteriorates

Engineering Contradiction:

Improveadhesive bond strengthVSAvoidchemical resistance

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent selects specific polyols with particular chemical structures (polyester, polycaprolactone, polycarbonate) and controls their molecular weight and functional group content. These parameter changes result in an adhesive that maintains strong bonding while exhibiting resistance to chemicals including oleic acid and alcohol, resolving the contradiction between bond strength and chemical resistance.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs a functional acid containing compound that provides chemical resistance through a temporary or sacrificial mechanism, protecting the main adhesive bond from chemical degradation while maintaining overall bond integrity.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Stability of the object's composition

If adhesive is designed for high temperature stability, then anti-lifting performance is improved, but drop resistance deteriorates

Engineering Contradiction:

Improvehigh temperature peel creep resistanceVSAvoiddrop resistance

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The patent optimizes the glass transition temperature and molecular weight parameters of the polyol component to achieve high temperature stability and anti-lifting performance. Simultaneously, the incorporation of flexible segments and controlled crosslinking maintains drop resistance, resolving the contradiction between thermal stability and impact resistance.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates an adhesive with dynamic molecular structure that can adapt its mechanical properties based on temperature and stress conditions. The polyurethane matrix provides thermal stability while incorporating flexible chains that absorb impact energy during drops, allowing the adhesive to maintain both high temperature performance and drop resistance.

Inventive Principle:

Principle #15Dynamics

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 polyurethane adhesive composition exhibits exceptional high temperature peel creep, anti-lifting performance, tensile drop resistance, and chemical resistance, outperforming traditional acrylic and polyurethane-based adhesives, maintaining adhesion under various stresses and chemical exposures.

Implementation Method 1

a polyol component with specific solubility parameters and hydrogen bonding

Methodology Applied

Scientific EffectHydrogen bonding:

Implementation Method 2

the polyol component has a total solubility parameter ranging from 10 to 14 (cal/cm³)

Methodology Applied

Scientific EffectSolubility parameter:

Data Source

PatentEP3792325A1Chemical resistant polyurethane adhesive

Publication Date: 2021.03.17 3M INNOVATIVE PROPERTIES CO

Figure 1

AI summary

A pressure sensitive adhesive composition includes a polyurethane polymer that includes the reaction product of an aliphatic polyisocyanate component, a polyol component, and a functional acid containing compound. The polyol component has a total solubility parameter ranging from 10 to 14 (cal/cm3)1/2.