Thermoformable Abrasion-Resistant Coating for Electronic Covers

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Solution Overview

Problem

Covers for electronic devices are prone to surface damage such as gouging and scuffing during handling and use, which affects their performance and aesthetic appearance, and existing solutions do not adequately address the need for protection and thermoformability.

Innovation Solution

A protective cover comprising a unitary thermoplastic polymer film with a low surface energy abrasion-resistant layer, featuring a curable composition of urethane (meth)acrylate compounds, (meth)acrylate monomers, silicone (meth)acrylate, and a photoinitiator, which is thermoformable and provides enhanced durability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a hard coat layer is applied to protect the cover surface, then abrasion resistance is improved, but the ability to undergo thermoforming without cracking deteriorates

Engineering Contradiction:
Improveabrasion resistanceVSAvoidthermoformability
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The patent modifies the chemical composition parameters of the curable coating layer by incorporating specific ratios of flexible polymer resins (20-80 wt%), rigid oligomers (20-80 wt%), and monomers (1-30 wt%). This parameter optimization allows the coating to achieve both abrasion resistance and flexibility required for thermoforming without cracking.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite curable composition combining multiple material types: flexible polymer resins for crack prevention, rigid oligomers for hardness and abrasion resistance, and monomers for crosslinking. This composite approach enables the coating to simultaneously provide protection and maintain thermoformability.

Inventive Principle:
Principle #40Composite materials

2Reliability

If a protective coating is applied to prevent surface damage, then durability is improved, but the conformability to complex device shapes deteriorates

Engineering Contradiction:
ImprovedurabilityVSAvoidconformability
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent adjusts the viscosity and flexibility parameters of the curable composition by selecting specific resin and monomer combinations, enabling the coating to flow and conform to complex three-dimensional device shapes while maintaining durability after curing.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs a flexible curable coating layer that can be applied as a thin film over the display cover, allowing it to conform to complex shapes. The flexible polymer resin content (20-80 wt%) provides the necessary elasticity for conformability while the cured structure maintains protective durability.

Inventive Principle:
Principle #30Flexible shells and thin films

3Ease of manufacture

If a single coating of hard coat material is used, then manufacturing simplicity is improved, but protection against gouging and scuffing deteriorates

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidsurface damage resistance
Core Design Contradiction:
Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent applies a single-layer curable coating that functions as a composite material system, integrating flexible polymers, rigid oligomers, and crosslinking monomers. This single composite layer provides comprehensive protection against gouging and scuffing while maintaining manufacturing simplicity, eliminating the need for multiple separate coating layers.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent optimizes the chemical composition parameters within the single coating layer to achieve enhanced protective properties. By adjusting the ratios of oligomers (for hardness), polymers (for flexibility), and monomers (for crosslink density), the single layer achieves superior resistance to surface damage compared to conventional single-layer coatings.

Inventive Principle:
Principle #35Parameter changes

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 effectively protects electronic device covers from physical damage while allowing for thermoforming processes, ensuring both durability and conformity to various device shapes without cracking, thus maintaining performance and appearance.

Implementation Method 1

the curable composition comprising components: a) 70 to 95 weight percent of urethane (meth)acrylate compound having an average (meth)acrylate functionality of 3 to 9, based on the total weight of components a) to d); b) 2 to 20 weight percent (meth)acrylate monomer having a (meth)acrylate functionality of 1 to 2, based on the total weight of components a) to d), wherein the (meth)acrylate monomer is not a urethane (meth)acrylate compound; c) 0.5 to 2 weight percent of silicone (meth)acrylate, based on the total weight of components a) to d); and d) optional effective amount of photoinitiator

Methodology Applied
Scientific EffectPhotopolymerization: Photopolymerisation

Implementation Method 2

a low surface energy abrasion resistant layer disposed on the first major surface of the first unitary thermoplastic polymer film

Methodology Applied
Scientific EffectAbrasion resistance: Abrasion

Data Source

PatentEP3723977B1Composite film, protective cover for an electronic device, and methods of making the same
Publication Date: 2022.01.26 3M INNOVATIVE PROPERTIES CO
  • EP3723977B1 patent drawingFigure 1~2
  • EP3723977B1 patent drawingFigure 3~4
  • EP3723977B1 patent drawing

AI summary

A composite film comprises: a first unitary thermoplastic polymer film; a low surface energy abrasion resistant layer disposed on the first unitary thermoplastic polymer film; a first adhesive layer proximate and securely bonded to the first unitary thermoplastic polymer film; a second unitary thermoplastic polymer film bonded to the first adhesive layer; and a second adhesive layer bonded to the second unitary thermoplastic polymer film opposite the first adhesive layer. A protective cover for an electronic device comprises: a first unitary thermoplastic polymer film; a low surface energy abrasion resistant layer disposed on the first unitary thermoplastic polymer film; a first adhesive layer proximate and securely bonded to the first unitary thermoplastic polymer film. The low surface energy abrasion resistant layer comprises an at least partially cured curable composition comprising components, based on the total weight of components a) to d): a) 70 to 95 weight percent of urethane (meth)acrylate compound having an average (meth)acrylate functionality of 3 to 9; b) 2 to 20 weight percent (meth)acrylate monomer having a (meth)acrylate functionality of 1 to 2, wherein the (meth)acrylate monomer is not a urethane (meth)acrylate compound; c) 0.5 to 2 weight percent of silicone (meth)acrylate; and d) optional effective amount of photoinitiator. Methods of making are also disclosed.