Primer Layer Coating Composition for Optical Elements

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Solution Overview

Problem

Plastic optical elements, such as ophthalmic lenses, face issues with impact resistance and adhesion of coatings due to the brittleness of anti-reflection coatings and the trend towards thinner lenses, which leads to cracking and reduced product life.

Innovation Solution

A coated optical element with a primer layer formed by cationic polymerization of a composition containing an epoxy monomer and a vinyl ether monomer, which improves impact resistance and adhesion between the substrate and coating layers, specifically designed for use with anti-reflection coatings.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If anti-reflection coating is applied to plastic optical elements, then optical transmittance is improved, but the coating becomes brittle and cracks easily under impact

Engineering Contradiction:
Improveoptical transmittanceVSAvoidimpact resistance
Core Design Contradiction:
Illumination intensityVSReliability

Solution Approach 1:

A primer layer is introduced as an intermediary between the plastic optical element substrate and the anti-reflection coating. This primer layer consists of a polymer matrix with embedded elastomeric particles that act as shock-absorbing intermediaries, preventing direct stress transfer from the brittle AR coating to the substrate during impact events, thereby reducing cracking while maintaining optical properties

Inventive Principle:
Principle #24Intermediary (Mediator)

2Length of moving object

If lens thickness is reduced for aesthetic reasons, then visual appearance is improved, but impact resistance and coating adhesion deteriorate

Engineering Contradiction:
Improvelens thicknessVSAvoidimpact resistance
Core Design Contradiction:
Length of moving objectVSReliability

Solution Approach 1:

The primer layer employs a composite material structure combining a polymer matrix with dispersed elastomeric particles. This composite formulation provides enhanced toughness and impact resistance in thin lenses by allowing the elastomeric particles to absorb impact energy through deformation, compensating for the reduced structural thickness of the lens itself

Inventive Principle:
Principle #40Composite materials

3Strength

If hard coating layers are applied to improve abrasion resistance, then surface durability is improved, but adhesion to the optical element substrate deteriorates

Engineering Contradiction:
Improveabrasion resistanceVSAvoidadhesion
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The primer layer serves as an adhesion-promoting intermediary between the optical element substrate and the hard coating layer. The polymer matrix provides bonding sites for both the substrate and the abrasion-resistant coating, while the elastomeric particles create a flexible interface that accommodates thermal and mechanical stresses, preventing delamination and maintaining strong adhesion throughout the product lifecycle

Inventive Principle:
Principle #24Intermediary (Mediator)

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 primer layer enhances the impact resistance and adhesion of optical elements, particularly those with anti-reflection coatings, thereby extending the product life and addressing the challenges of coating brittleness and lens thickness.

Implementation Method 1

the primer layer being formed by cationic polymerisation of a coating composition containing an effective amount of: an epoxy monomer; and a vinyl ether monomer

Methodology Applied
Scientific EffectCationic polymerization: Photopolymerisation

Data Source

PatentUS9975302B2Primer layer coating compositions
Publication Date: 2018.05.22 CARL ZEISS VISION AUSTRALIA HOLDINGS LTD

AI summary

The present invention provides a coated optical element including an optical substrate and a primer layer that is formed by cationic polymerisation of a coating composition containing an effective amount of an epoxy monomer and a vinyl ether monomer. The optical element may be an ophthalmic lens.