Hard Coating Composition for Plastic Lenses

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Solution Overview

Problem

High refractive index hard coating layers on plastic optical substrates suffer from interference patterns and inferior weathering performance due to differences in refractive index and photocatalytic degradation, respectively, which affect the appearance and durability of spectacle lenses.

Innovation Solution

A hard coating composition comprising organosilicon compound hydrolysates, titanium-oxide-based composite metal oxide fine particles, dicyandiamide, organic polycarboxylic acid, and a Co(II) compound is used to form a hard coating layer that balances refractive index and weathering resistance, with specific ratios and additives to enhance scratch resistance and heat resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a hard coating layer is formed on high refractive index plastic lenses, then scratch resistance is improved, but interference patterns occur due to refractive index difference

Engineering Contradiction:

Improvescratch resistanceVSAvoidappearance

Core Design Contradiction:

StrengthVSShape

Solution Approach 1:

The patent changes the refractive index parameter of the hard coating layer by incorporating high refractive index inorganic oxide microparticles (titanium oxide, zirconium oxide, tantalum oxide) to match the refractive index of high refractive index plastic lenses (1.60 or higher), thereby eliminating interference patterns while maintaining scratch resistance

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite hard coating layer combining organic resin components with inorganic oxide microparticles, achieving both high scratch resistance through the hard inorganic particles and refractive index matching through the composite structure

Inventive Principle:

Principle #40Composite materials

2Shape

If titanium oxide is added to improve refractive index of hard coating layer, then interference patterns are reduced, but weathering performance deteriorates due to photocatalytic action

Engineering Contradiction:

Improverefractive index uniformityVSAvoidweathering performance

Core Design Contradiction:

ShapeVSReliability

Solution Approach 1:

The patent introduces an intermediary oxide layer (silicon oxide, aluminum oxide, or titanium oxide) coating the surface of high refractive index inorganic oxide microparticles, which acts as a barrier to suppress photocatalytic action while maintaining the high refractive index benefit

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent converts the harmful photocatalytic effect of titanium oxide into a beneficial structure by using it as a core material for composite microparticles, where the harmful surface is passivated with a protective oxide coating, thereby eliminating the harm while preserving the refractive index advantage

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Reliability

If evaporation coating is applied to improve weathering performance, then photocatalytic degradation is reduced, but heat resistance performance becomes insufficient causing coating peeling

Engineering Contradiction:

Improveweathering performanceVSAvoidadhesion

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent creates a composite structure where inorganic oxide microparticles are embedded in an organic resin matrix, forming a unified hard coating layer that provides both weathering resistance and heat resistance, eliminating the adhesion problems of separate evaporation coatings

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent merges the weathering protection function and the structural integrity function into a single integrated hard coating layer, rather than using separate protective coatings, thereby achieving both weathering performance and heat resistance simultaneously

Inventive Principle:

Principle #5Merging (Combining)

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 improves the refractive index and weathering performance of the hard coating layer, reducing the likelihood of cracks and peeling while maintaining optical clarity and durability, as demonstrated by improved ultraviolet exposure tests and adhesion evaluations.

Implementation Method 1

A. Organosilicon compound's hydrolysate

Methodology Applied

Scientific EffectHydrolysis: Hydrolysis

Implementation Method 2

B. Titanium-oxide-based composite metal oxide fine particles

Methodology Applied

Scientific EffectRefraction: Refraction

Implementation Method 3

E. Co(II) compound

Methodology Applied

Scientific EffectCatalysis: Catalysis

Implementation Method 4

C. Dicyandiamide D. Organic polycarboxylic acid

Methodology Applied

Scientific EffectChemical Bonding: Chemical Bonding

Data Source

PatentEP1895333B1Hard coating composition and plastic optical product

Publication Date: 2011.03.02 TOKAI OPTICAL CO LTD

AI summary

Applying liquid for hard coating that is made of organic silane compounds, the fine particles of composite mainly based on titanium-oxide, which also includes zirconium-oxide and silicon-oxide etc., dicyandiamide, itaconic acid, and Co(II) acetylacetonate compound on plastic lenses in order to form a hard coating layer after hardening.