Polybutadiene Adhesive Resin for Foldable Display Reliability

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Solution Overview

Problem

Existing adhesive members in display devices face challenges in maintaining stable coupling, impact resistance, adhesion reliability, and light fastness, which can degrade display quality over time.

Innovation Solution

A resin composition comprising polybutadiene with unsaturated bonds, a photoinitiator, and (meth)acrylate monomers, excluding urethane (meth)acrylate-terminated polybutadiene, is used to create an adhesive member with low viscosity and high tensile modulus, ensuring strong adhesion and resistance to discoloration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional adhesive members are used in display devices, then initial bonding is achieved, but adhesion reliability and light fastness degrade over time

Engineering Contradiction:

Improveadhesion reliabilityVSAvoidservice life

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent changes the chemical composition parameters of the adhesive by specifying polybutadiene content (1-10 wt%), photoinitiator concentration, and monomer ratios to achieve optimal long-term adhesion and light fastness properties

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention creates a composite adhesive system combining polybutadiene, photoinitiators, and (meth)acrylate monomers/oligomers that work synergistically to provide both initial bonding strength and long-term reliability

Inventive Principle:

Principle #40Composite materials

2Stability of the object's composition

If adhesive member provides strong coupling, then component stability is improved, but impact resistance decreases

Engineering Contradiction:

Improvecoupling stabilityVSAvoidimpact resistance

Core Design Contradiction:

Stability of the object's compositionVSStrength

Solution Approach 1:

The patent optimizes the balance between coupling strength and impact resistance by controlling the molecular weight distribution and composition ratios of the adhesive materials

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The adhesive composition provides dynamic mechanical properties that allow the material to transition from rigid (for stable coupling) to flexible (for impact absorption) states

Inventive Principle:

Principle #15Dynamics

3Strength

If adhesive member ensures high adhesion strength, then component coupling is improved, but light fastness deteriorates

Engineering Contradiction:

Improveadhesion strengthVSAvoidlight-induced degradation

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent converts the potentially harmful effect of UV light on adhesive degradation into a beneficial curing mechanism by incorporating photoinitiators that activate only during the curing process, leaving the finished adhesive resistant to light-induced degradation

Inventive Principle:

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

Solution Approach 2:

The invention modifies the chemical structure parameters by selecting specific monomers and oligomers with low light absorption coefficients to achieve both strong adhesion and excellent light fastness

Inventive Principle:

Principle #35Parameter changes

4Strength

If resin composition has high viscosity, then adhesion strength is improved, but ease of application deteriorates

Engineering Contradiction:

Improveadhesion strengthVSAvoidease of application

Core Design Contradiction:

StrengthVSEase of operation

Solution Approach 1:

The patent controls the viscosity parameter through careful selection of oligomer molecular weights and concentrations to achieve optimal flow characteristics for inkjet printing while maintaining adequate adhesion strength

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The adhesive composition exhibits dynamic viscosity that allows easy application through inkjet printing at low viscosity, then builds adhesion strength through chemical curing

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 adhesive member exhibits excellent impact resistance, adhesion reliability, and light fastness, maintaining display quality and enabling repeated folding and unfolding of flexible display devices.

Implementation Method 1

at least one photoinitiator

Methodology Applied

Scientific EffectPhotopolymerization: Photopolymerisation

Data Source

PatentUS20250326956A1Resin composition, adhesive member, and display device including the adhesive member

Publication Date: 2025.10.23 SAMSUNG DISPLAY CO LTD

AI summary

A resin composition is disclosed. The resin composition may include a polybutadiene having an unsaturated bond in at least one selected from among a main chain and a side chain, at least one photoinitiator, at least one monofunctional (meth)acrylate monomer, and/or at least one (meth)acrylate oligomer. The resin composition may not include a urethane (meth)acrylate-terminated polybutadiene. An amount of the polybutadiene may be about 1 wt % or more and less than about 10 wt % based on a total of 100 wt % of the resin composition. The resin composition may have a shear viscosity of about 8 mPa·s to about 50 mPa·s as measured at a temperature of about 25° C. The resin composition may have a tensile modulus of about 10 MPa to about 900 MPa at a temperature of about 25° C. after photocuring.