Photocurable Optical Hard Coats for Weather-Resistant Adhesion

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Solution Overview

Problem

Existing photocurable compositions for optical articles, such as lenses, suffer from deteriorated adhesion due to ultraviolet light exposure, leading to reduced weather-resistant properties.

Innovation Solution

Incorporation of an ultraviolet absorber with a radical-polymerizable group into the photocurable composition, along with an inorganic oxide, a radical-polymerizable monomer, and a photopolymerization initiator, to enhance adhesion and durability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If a photocurable composition containing an ultraviolet absorber is used, then the curing speed is improved, but the adhesion deteriorates due to ultraviolet light exposure

Engineering Contradiction:

Improvecuring speedVSAvoidadhesion

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The patent converts the harmful effect of ultraviolet light (which causes deterioration and adhesion loss) into a beneficial effect by using the same ultraviolet light to drive photopolymerization of the ultraviolet absorber itself. The ultraviolet absorber contains a radical-polymerizable group that polymerizes upon UV irradiation, transforming the harmful UV exposure into a useful crosslinking reaction that enhances adhesion while maintaining fast curing speed

Inventive Principle:

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

Solution Approach 2:

The patent creates a composite system where the ultraviolet absorber serves dual functions: (1) absorbing ultraviolet light to prevent deterioration of the cured product, and (2) containing a radical-polymerizable group that participates in photopolymerization. This composite approach combines the protective function of UV absorption with the adhesive function of polymer network formation, resolving the contradiction between curing speed and adhesion

Inventive Principle:

Principle #40Composite materials

2Strength

If a thermosetting composition is used for the hard coat layer, then the hardness is improved, but the curing time is increased

Engineering Contradiction:

ImprovehardnessVSAvoidcuring time

Core Design Contradiction:

StrengthVSLoss of time

Solution Approach 1:

The patent replaces the thermal curing mechanism (thermosetting composition requiring heat treatment) with a photopolymerization mechanism using radical-polymerizable monomers and ultraviolet light. This substitution eliminates the need for prolonged thermal processing while achieving comparable or superior hardness through rapid UV-induced crosslinking, thereby reducing curing time significantly

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the curing parameters from thermal conditions (high temperature, long duration) to photonic conditions (UV light irradiation, short duration). By using radical-polymerizable monomers that undergo rapid polymerization upon UV exposure, the system achieves fast curing with reduced time loss while maintaining the hardness required for scratch resistance

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 composition provides a cured product with excellent weather-resistant adhesion, preventing ultraviolet-induced deterioration and maintaining adhesion over time, while offering a faster curing process than thermosetting methods.

Implementation Method 1

a photocurable composition includes an inorganic oxide, a radical-polymerizable monomer, an ultraviolet absorber including a radical-polymerizable group, and a photopolymerization initiator

Methodology Applied

Scientific EffectPhotopolymerization: Photopolymerisation

Implementation Method 2

an ultraviolet absorber including a radical-polymerizable group, suppressing this deterioration

Methodology Applied

Scientific EffectUltraviolet absorption: Absorption (EM radiation)

Data Source

PatentUS20250236737A1Photocurable composition, optical laminate, optical article, lens, and spectacles

Publication Date: 2025.07.24 TOKUYAMA CORP

AI summary

The present invention provides: a photocurable composition that makes it possible to provide a cured body having excellent weather-resistant adhesiveness; and an optical laminate, an optical article, a lens, and spectacles which include said cured body. One embodiment provides a photocurable composition. The photocurable composition comprises an inorganic oxide, a radical-polymerizable monomer, an ultraviolet absorber including a radically polymerizable group, and a polymerization initiator. The optical laminate comprises an optical base material and a hard coat layer. The hard coat layer is opposite from at least one main surface of the optical base material. The hard coat layer is a cured body of a photocurable composition according to an embodiment of the present invention.