Photocurable Composition High Refractive Index UV Absorption

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Solution Overview

Problem

Current methods for achieving high refractive index in photocurable optical materials face limitations due to sulfur's strong UV absorption, which inhibits photocuring, and existing alternatives result in inferior refractive indices.

Innovation Solution

A photocurable composition comprising sulfur with a cyclic structure, an episulfide compound, and a photopolymerization initiator, using specific ratios and additives to enhance refractive index and photocurability, particularly utilizing long wavelength light for curing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If sulfur is added to increase refractive index, then refractive index is improved, but photocuring is inhibited due to strong UV absorption

Engineering Contradiction:

Improverefractive indexVSAvoidphotocuring ability

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The patent changes the chemical structure parameter of sulfur from linear/cyclic forms to a specific tetrahedral structure (S8 ring), which fundamentally alters its UV absorption characteristics while maintaining high refractive index contribution

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite photocurable composition combining the specific sulfur compound with episulfide compounds and photopolymerization initiators, where each component compensates for the others' limitations to achieve both high refractive index and effective photocuring

Inventive Principle:

Principle #40Composite materials

2Reliability

If cyclic polysulfide compound is used instead of sulfur to enable photocuring, then photocurability is improved, but refractive index becomes inferior

Engineering Contradiction:

ImprovephotocurabilityVSAvoidrefractive index

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The patent changes the compositional parameter by using a specific ratio range of sulfur compound (1-28 parts by mass relative to episulfide compound), optimizing the balance between refractive index enhancement and photocuring capability

Inventive Principle:

Principle #35Parameter changes

3Productivity

If short wavelength UV light is used for photocuring, then curing speed is improved, but sulfur absorption strongly blocks the light

Engineering Contradiction:

Improvecuring speedVSAvoidlight absorption blocking

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful UV absorption property of sulfur into a beneficial feature by selecting a sulfur compound with tetrahedral structure that absorbs less in the effective photocuring wavelength range, while still providing high refractive index

Inventive Principle:

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

Solution Approach 2:

The patent employs a photopolymerization initiator system that can be activated by various wavelengths including visible light and UV, making the curing process universally effective regardless of the specific light source wavelength

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 achieves a high refractive index of 1.72 or more in the cured product, enabling the production of optical materials with improved performance.

Implementation Method 1

a photocurable composition comprising a sulfur (a) having a cyclic structure represented by the following formula (1), an episulfide compound (b), and a photopolymerization initiator (c)

Methodology Applied

Scientific EffectPhotopolymerization: Photopolymerisation

Data Source

PatentUS20240084136A1Photocurable composition, cured product thereof, and optical material containing said cured product

Publication Date: 2024.03.14 MITSUBISHI GAS CHEM CO INC

AI summary

According to the present invention, there can be provided a photocurable composition comprising a sulfur (a) having a cyclic structure represented by the following formula (1), an episulfide compound (b), and a photopolymerization initiator (c), wherein the content of the sulfur (a) is 1 to 28 parts by mass, with respect to the total mass (100 parts by mass) of the sulfur (a) and the episulfide compound (b):