Transparent Polyimide Film with POSS Hybrid for Flexible Display Cover Windows

Solution Overview

Problem

Conventional cover window materials for flexible displays, such as polyimide resins, face challenges with poor heat resistance, chemical resistance, mechanical strength, and yellowing due to exposure to external ultraviolet rays, which affect the visibility and durability of display devices.

Innovation Solution

A polyamic acid resin is developed by copolymerizing at least one diamine, one acid dianhydride, and polyhedral oligomeric silsesquioxane (POSS), where the POSS is integrated as a reactant to form an organic-inorganic hybrid, enhancing the resin's molecular weight and stability, leading to improved optical and mechanical properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If polyimide resin is used as cover window material, then heat resistance and chemical resistance are improved, but transparency deteriorates due to dark brown color from charge transfer complex formation

Engineering Contradiction:

Improveheat resistanceVSAvoidtransparency

Core Design Contradiction:

ReliabilityVSIllumination intensity

Solution Approach 1:

The patent uses a composite material system combining polyamic acid resin with inorganic particles (silica, alumina, or zirconia) having 1-10 nm particle diameter. This composite structure allows the material to maintain the heat resistance of polyimide resin while the inorganic particles suppress charge transfer complex formation, preventing dark brown coloration and maintaining transparency.

Inventive Principle:

Principle #40Composite materials

2Illumination intensity

If conventional plastic materials (polycarbonate, PMMA) are used for cover window, then transparency is improved, but heat resistance deteriorates with glass transition temperature of 150°C or less

Engineering Contradiction:

ImprovetransparencyVSAvoidheat resistance

Core Design Contradiction:

Illumination intensityVSTemperature

Solution Approach 1:

The patent creates a composite material combining polyamic acid resin with inorganic particles (silica, alumina, or zirconia) having 1-10 nm particle diameter. This composite structure allows the material to maintain the heat resistance of polyimide resin while the inorganic particles suppress charge transfer complex formation, preventing dark brown coloration and maintaining transparency.

Inventive Principle:

Principle #40Composite materials

3Adaptability or versatility

If polyimide-based resin is used for flexible display cover window, then flexibility is improved, but mechanical strength and scratch resistance deteriorate

Engineering Contradiction:

ImproveflexibilityVSAvoidscratch resistance

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The patent creates a composite material combining polyamic acid resin with inorganic particles (silica, alumina, or zirconia) having 1-10 nm particle diameter. This composite structure allows the material to maintain the heat resistance of polyimide resin while the inorganic particles suppress charge transfer complex formation, preventing dark brown coloration and maintaining transparency.

Inventive Principle:

Principle #40Composite materials

4Weight of moving object

If plastic cover window material is used for flexible display, then weight is reduced and flexibility is improved, but durability against fatigue failure from crack propagation deteriorates

Engineering Contradiction:

ImproveweightVSAvoiddurability against fatigue failure

Core Design Contradiction:

Weight of moving objectVSReliability

Solution Approach 1:

The patent creates a composite material combining polyamic acid resin with inorganic particles (silica, alumina, or zirconia) having 1-10 nm particle diameter. This composite structure allows the material to maintain the heat resistance of polyimide resin while the inorganic particles suppress charge transfer complex formation, preventing dark brown coloration and maintaining transparency.

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 resulting transparent polyimide film exhibits high light transmittance, low yellow index, and excellent mechanical properties, making it suitable for use as a cover window in flexible displays with enhanced visibility and durability.

Implementation Method 1

A polyamic acid resin is copolymerized including: at least one diamine; at least one acid dianhydride; and polyhedral oligomeric silsesquioxane (POSS)

Methodology Applied

Scientific EffectCopolymerization: Chemical Bonding

Data Source

PatentUS20240034838A1Polyamic acid resin and polyimide film using the same

Publication Date: 2024.02.01 DOOSAN CORP

AI summary

A polyamic acid resin is copolymerized including: at least one diamine; at least one acid dianhydride; and polyhedral oligomeric silsesquioxane, and a transparent polyimide film is formed using the polyamic acid resin. The transparent polyimide film secures both excellent optical and mechanical properties through organic-inorganic hybrid formation, thus being applicable as a cover window for display devices.