Flexible Glass with Polymer Coating for Ultra-Low Bending Curvature

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Solution Overview

Problem

Conventional glass articles are not flexible enough to achieve ultra-low bending curvature while maintaining a thin profile and necessary durability, scratch resistance, and optical characteristics for applications like flexible display devices.

Innovation Solution

A flexible glass article with a compressive stress region and a coating on one surface, where the coating is thicker than the glass and has a specific elastic modulus, allowing the glass to bend without fracturing at small radii and withstand repeated bending cycles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Shape

If glass thickness is reduced to achieve smaller bending radius, then flexibility and bendability are improved, but glass becomes too thin to maintain structural integrity and durability

Engineering Contradiction:
Improvebending radiusVSAvoidstructural integrity
Core Design Contradiction:
ShapeVSStrength

Solution Approach 1:

The patent applies composite materials by combining glass with a flexible polymer layer to create a flexible glass article. The glass element (25-100 μm thick) is bonded to a flexible polymer layer, allowing the composite structure to bend at small radii (1-10 mm) while maintaining structural integrity. The polymer layer compensates for the thinness of the glass, preventing fracture during bending cycles.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent uses a flexible polymer layer bonded to the glass element to enable flexibility. This thin film approach allows the glass article to achieve bend radii of 1-10 mm without breaking, as the polymer layer accommodates the bending stress that would otherwise cause the thin glass to fracture.

Inventive Principle:
Principle #30Flexible shells and thin films

2Strength

If glass is chemically strengthened to increase surface compression for flexibility, then bendability is improved, but bending radius remains relatively large (greater than 20 mm)

Engineering Contradiction:
Improvesurface compressionVSAvoidbending radius
Core Design Contradiction:
StrengthVSShape

Solution Approach 1:

The patent changes the physical parameters of the glass element, including thickness (25-100 μm) and compressive stress (at least 300 MPa at the surface), to achieve ultra-low bending curvature. By optimizing these parameters and combining them with a flexible polymer layer, the glass article achieves bend radii of 1-10 mm, overcoming the limitation of conventional chemically strengthened glass.

Inventive Principle:
Principle #35Parameter changes

3Length of moving object

If glass etching is used to reduce thickness below 25 μm, then bending radius is reduced, but uniformity and manufacturing quality deteriorate

Engineering Contradiction:
Improveglass thicknessVSAvoiduniformity
Core Design Contradiction:
Length of moving objectVSManufacturing precision

Solution Approach 1:

Instead of etching glass to achieve ultra-thin dimensions (which causes uniformity problems), the patent bonds a flexible polymer layer to a glass element of 25-100 μm thickness. This approach achieves the necessary flexibility and small bending radius without compromising glass manufacturing uniformity, as the polymer layer provides the flexibility rather than ultra-thin etched glass.

Inventive Principle:
Principle #30Flexible shells and thin films

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 solution enables flexible glass articles to maintain structural integrity and optical properties when bent to small radii, offering improved durability and resistance to scratches and UV exposure, suitable for use in portable electronic devices.

Implementation Method 1

a coating directly cured by ultraviolet radiation on the second surface of the glass element

Methodology Applied
Scientific EffectUltraviolet radiation curing: Photopolymerisation

Implementation Method 2

the compressive stress region having a compressive stress of at least about 300 MPa at the first surface of the glass element

Methodology Applied
Scientific EffectCompressive stress: Compression

Data Source

PatentEP3330235B1Flexible glass article having a low bending curvature and method of making the same
Publication Date: 2024.10.02 SAMSUNG DISPLAY CO LTD
  • EP3330235B1 patent drawingFigure 1
  • EP3330235B1 patent drawingFigure 2A~2B
  • EP3330235B1 patent drawingFigure 3

AI summary

Flexible glass articles having modified bending radii and methods of making same provide an ultra-low bending curvature, while still retaining a thin profile and other favorable characteristics of glass.