Silazane Coating for Polyimide Cover Window Hardness and Clarity

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Solution Overview

Problem

Existing polyimide-based films for flexible display apparatuses do not adequately meet the optical and mechanical properties required for cover windows, necessitating improvements in hardness, moisture permeability, and chemical resistance.

Innovation Solution

A silazane-based compound is used to form a coating composition that enhances the properties of a light-transmitting film, including a support layer and a first coating layer with specific molecular structures and thickness, and optionally a second coating layer, to improve adhesion, optical properties, and chemical resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If polyimide-based film is used for cover window, then hardness is improved, but optical properties and mechanical properties do not satisfy requirements

Engineering Contradiction:
ImprovehardnessVSAvoidoptical properties
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The patent uses a silazane-based compound as a coating material applied over the polyimide-based film. This creates a composite structure where the polyimide provides hardness and the silazane coating improves optical properties, moisture permeability, and chemical resistance. The coating composition includes the silazane-based compound and a solvent, forming a multi-layer composite material system that integrates the advantages of both components.

Inventive Principle:
Principle #40Composite materials

2Strength

If polyimide-based film is used for cover window, then hardness is improved, but moisture permeability and chemical resistance are insufficient

Engineering Contradiction:
ImprovehardnessVSAvoidmoisture permeability
Core Design Contradiction:
StrengthVSObject-affected harmful factors

Solution Approach 1:

The silazane-based compound undergoes chemical transformation when exposed to moisture, forming a crosslinked gel structure. This parameter change from monomeric to polymeric structure creates a barrier that reduces moisture permeability. The compound's chemical structure includes silazane groups that react with water to form a protective network, fundamentally changing the material's permeability characteristics.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If coating layer is added to improve physical properties, then adhesion and optical properties are improved, but manufacturing complexity increases

Engineering Contradiction:
ImproveadhesionVSAvoidcoating process
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The silazane-based compound performs multiple functions simultaneously: it improves adhesion between layers, enhances optical properties, provides moisture barrier, and offers chemical resistance. The compound's molecular structure includes functional groups that automatically react with moisture in the environment, creating a self-healing protective layer without requiring additional processing steps or complex manufacturing procedures.

Inventive Principle:
Principle #25Self-service

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 silazane-based compound improves the adhesion and optical properties of polyimide-based films, enhancing their chemical resistance, flexibility, and moisture-barrier properties, while maintaining high light transmittance and reducing the yellow index.

Implementation Method 1

a first coating layer on the support layer, wherein the first coating layer includes a cured product of a silazane-based compound

Methodology Applied
Scientific EffectChemical reaction: Chemical Bonding

Implementation Method 2

improve the adhesion and optical properties of polyimide-based films, enhancing their chemical resistance, flexibility, and moisture-barrier properties

Methodology Applied
Scientific EffectMoisture barrier: Physical Containment

Data Source

PatentEP4174112B1Silazane-based compound, coating composition comprising same, light-transmitting film having coating layer, and display device comprising light-transmitting film
Publication Date: 2025.12.10 KOLON INDUSTRIES INC
  • EP4174112B1 patent drawingFigure 1
  • EP4174112B1 patent drawingFigure 2
  • EP4174112B1 patent drawingFigure 3

AI summary

Disclosed are a silazane-based compound represented by Formula 1, a coating composition containing the silazane-based compound, a light-transmitting film including a first coating layer containing the silazane-based compound, and a display apparatus including the light-transmitting film.