Polyimide Substrate UV Absorber Adhesion Bending Resistance

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Solution Overview

Problem

Existing stacked bodies for flexible displays lack sufficient bending resistance due to decreased adhesiveness between the polyimide substrate and the functional layer, which is exacerbated by ultraviolet ray deterioration.

Innovation Solution

Incorporating an ultraviolet absorber into the functional layer of a stacked body for a display device, where the polyimide substrate is coated with a functional layer containing an ultraviolet absorber, to maintain adhesiveness and enhance bending resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a polyimide substrate with a functional layer is used for flexible displays, then flexibility and thinness are improved, but bending resistance deteriorates due to decreased adhesiveness between the substrate and functional layer

Engineering Contradiction:

ImproveflexibilityVSAvoidbending resistance

Core Design Contradiction:

Object-affected harmful factorsVSStrength

Solution Approach 1:

The patent applies preliminary action by incorporating an ultraviolet absorber into the functional layer before the deterioration can occur. This preventive measure blocks ultraviolet rays from reaching and degrading the polyimide substrate, thereby maintaining adhesiveness and bending resistance throughout the product lifecycle.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The ultraviolet absorber acts as an intermediary substance between the functional layer and the polyimide substrate. It absorbs harmful ultraviolet radiation before it can cause deterioration, protecting the interface between layers and maintaining their adhesiveness.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of manufacture

If the functional layer is placed directly on the polyimide substrate, then processability is improved, but adhesiveness deteriorates due to ultraviolet ray deterioration

Engineering Contradiction:

ImproveprocessabilityVSAvoidadhesiveness

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The ultraviolet absorber serves as a protective intermediary within the functional layer, blocking ultraviolet radiation from degrading the polyimide substrate. This maintains the chemical integrity and adhesiveness of the substrate-functional layer interface without complicating the manufacturing process.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The functional layer is formulated as a composite material containing both the functional components and an ultraviolet absorber. This composite structure provides both the desired functionality and ultraviolet protection, ensuring long-term adhesiveness while maintaining ease of manufacture.

Inventive Principle:

Principle #40Composite materials

3Strength

If ultraviolet protection is added to maintain adhesiveness, then bending resistance is improved, but device complexity increases

Engineering Contradiction:

Improvebending resistanceVSAvoidstructure complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The patent merges the ultraviolet protection function with the existing functional layer by incorporating an ultraviolet absorber into it. This consolidation provides both functional performance and ultraviolet protection in a single layer, avoiding additional structural complexity while maintaining bending resistance.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The functional layer is designed with multi-functionality, serving both its primary functional purpose and providing ultraviolet absorption. This universal approach eliminates the need for separate protection layers, maintaining simplicity while improving bending resistance through sustained adhesiveness.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 an ultraviolet absorber in the functional layer effectively suppresses deterioration caused by ultraviolet rays, maintaining the adhesiveness between the polyimide substrate and the functional layer, and thereby achieving improved bending resistance.

Implementation Method 1

a functional layer including an ultraviolet absorber, placed on one surface of the polyimide substrate

Methodology Applied

Scientific EffectUltraviolet absorption: Absorption (EM radiation)

Data Source

PatentUS20250160172A1Stacked body for display devices and display device

Publication Date: 2025.05.15 DAI NIPPON PRINTING CO LTD

AI summary

The present disclosure provides a stacked body for a display device comprising a polyimide substrate, and a functional layer including an ultraviolet absorber, placed on one surface of the polyimide substrate, wherein a difference of a crack elongation of the stacked body for a display device measured by a predetermined method, before and after a predetermined light resistance test, is 0.6 or less.