Polythiourethane Glass Catalyst System for Optical Clarity

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Solution Overview

Problem

Current methods for producing organic polythiourethane glass with high refractive index and good optical and physico-mechanical properties face challenges such as the use of toxic organometallic catalysts, complexity in production processes, and issues with optical defects like opacity and turbidity, as well as the need for simple and inexpensive industrial-scale production.

Innovation Solution

A polymerization catalyst system comprising a mixture of tertiary amine and disubstituted phosphoric acid, without organometallic compounds, is used in a polymerizable liquid composition containing cycloaliphatic diisocyanate and polythiols, which allows for a simple casting process with improved reactivity and mold release properties, reducing the need for additional mold release agents and enhancing the refractive index and toughness of the resulting glass.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If organometallic catalysts are used for polymerization, then reactivity is improved, but toxicity and environmental harm increase

Engineering Contradiction:

Improvepolymerization reactivityVSAvoidtoxicity

Core Design Contradiction:

SpeedVSObject-affected harmful factors

Solution Approach 1:

The patent replaces persistent organometallic catalysts with organic catalysts that are less toxic and more environmentally friendly, sacrificing some catalytic longevity but gaining in safety and environmental compatibility

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent introduces an organic catalyst system (amines or carbodiimides) as an intermediary substance that mediates the polymerization reaction between isocyanates and thiols, replacing the harmful organometallic catalyst while maintaining reaction efficiency

Inventive Principle:

Principle #24Intermediary (Mediator)

2Manufacturing precision

If complex catalyst systems are used, then polymerization control is improved, but process complexity increases

Engineering Contradiction:

Improvepolymerization controlVSAvoidprocess complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates unnecessary complex components from the catalyst system, using simple organic catalysts like amines or carbodiimides that provide sufficient control without adding process complexity

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent optimizes the molecular weight and functionality parameters of the thiol monomer to achieve desired polymerization control and material properties without requiring complex catalyst formulations

Inventive Principle:

Principle #35Parameter changes

3Illumination intensity

If high refractive index is achieved through polythiourethane composition, then optical properties are improved, but production cost increases

Engineering Contradiction:

Improverefractive indexVSAvoidproduction cost

Core Design Contradiction:

Illumination intensityVSEase of manufacture

Solution Approach 1:

The patent adjusts the molecular weight and functionality parameters of the thiol monomer to achieve the desired refractive index and optical properties while maintaining cost-effective production through simpler processing

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 enables the production of transparent, high-refractive-index polythiourethane glass with excellent optical and mechanical properties, improved toughness, and impact strength, while being simpler, safer, and more cost-effective for industrial-scale production, avoiding the limitations of previous technologies.

Implementation Method 1

a polymerization catalyst for organic polythiourethane glass which does not contain organometallic compounds and consists of a mixture of a tertiary amine represented by the following general formula (1)... a disubstituted phosphoric acid having general formula (2)...

Methodology Applied

Scientific EffectCatalysis: Catalysis

Data Source

PatentEP2571914B1A polymerization catalyst for polythiourethanes, polymerizable liquid composition and process for the production of organic polythiourethane glass with a high refractive index

Publication Date: 2021.12.29 MITSUI CHEMICALS INC

AI summary

Polymerization catalysts are described for organic polythiourethane glass which do not contain organometallic compounds, and consisting of a mixture of a tertiary aliphatic amine and a disubstituted phosphoric acid in a molar ratio ranging from 1/1.3 to 1/20. Polymerizable liquid compositions of the polythiourethane type are also described, essentially consisting of three components (A), (B) and (C), wherein component (A) contains at least one cycloaliphatic diisocyanate monomer wherein the weight percentage of free isocyanate groups in said component (A) ranges from about 20% to about 50% by weight, preferably from about 25% to about 40% by weight, with respect to the total weight of component (A); component (B) contains at least one polythiol having a molecular weight ranging from 50 to 1,200 g/moles, preferably from 100 to 1000 g/moles, and a functionality ranging from 2 to 5, preferably from 2 to 4, said components (A) and (B) being present in a weight ratio varying from 0.5:1 to 2:1; component (C) being said polymerization catalyst.The process is also described for the production of organic glass starting from said polymerizable liquid compositions of the polythiourethane type.