Polythiourethane Optical Material Impact Resistance via Acidic Phosphoric Ester
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Solution Overview
Problem
Polythiourethane-based optical materials derived from isophorone diisocyanate lack impact resistance and are prone to modification by tin compounds, leading to unstable polymerization and reduced product yield.
Innovation Solution
A polymerizable composition comprising isophorone diisocyanate, thiols, acidic phosphoric acid ester, and a tin compound, with specific weight ratios to inhibit modification and enhance heat resistance, transparency, and impact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If isophorone diisocyanate is used to produce polythiourethane optical materials, then the materials achieve high refractive index, low dispersion, and excellent transparency, but the materials exhibit poor impact resistance
Solution Approach 1:
The patent uses a composite formulation combining isophorone diisocyanate with specific polythiol compounds (having different reaction rates), acidic phosphoric acid ester, and tin compound catalyst. This composite approach allows achieving both high optical properties (refractive index 1.58-1.62, low dispersion with Abbe number 30-40) and excellent impact resistance (passing 16.3g steel ball drop test from 127cm) simultaneously.
2Productivity
If tin compound catalyst is added to isophorone diisocyanate, then polymerization is accelerated, but the isocyanate undergoes modification leading to unstable polymerization and reduced product yield
Solution Approach 1:
The patent introduces acidic phosphoric acid ester as an intermediary substance that mediates between the tin compound catalyst and isophorone diisocyanate. The acidic phosphoric acid ester prevents direct harmful interaction between tin compound and isocyanate, eliminating gel-like substance formation and modification reactions, while still allowing the tin compound to effectively catalyze the polymerization of polythiol with isocyanate, achieving stable polymerization with high yield.
Solution Approach 2:
The patent converts the potentially harmful modification reaction between tin compound and isophorone diisocyanate into a beneficial process by controlling the reaction conditions and adding acidic phosphoric acid ester. The tin compound's reactivity, which initially causes modification, is redirected to efficiently catalyze the desired polythiourethane formation, improving polymerization rate while maintaining stability through proper formulation.
3Productivity
If polythiol and alkyltin halide polymerization catalyst are added to polyisocyanate compound, then polymerization proceeds, but the polyisocyanate is modified by moisture leading to unstable composition
Solution Approach 1:
The patent uses acidic phosphoric acid ester as a protective intermediary that prevents moisture-induced modification of polyisocyanate during the polymerization process. This intermediary maintains composition stability while allowing the alkyltin halide catalyst to effectively promote polymerization between polyisocyanate and polythiol.
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 polythiourethane molded product with excellent heat resistance, transparency, refractive index, low dispersion, and low specific gravity, while preventing gel-like substance formation and improving yield.
Implementation Method 1
a tin compound (D) and a predetermined amount of an acidic phosphoric acid ester (C) with respect to the tin compound (D), wherein the isophorone diisocyanate and the thiol are mixed in the presence of the acidic phosphoric acid ester (C)
Implementation Method 2
the isophorone diisocyanate and the thiol are mixed in the presence of the acidic phosphoric acid ester (C), the modification of the isophorone diisocyanate is inhibited, and furthermore, a gel-like substance is not generated
Data Source
AI summary
Provided is a polymerizable composition for an optical material including (A) isocyanates having two or more isocyanato groups, which include at least an isophorone diisocyanate, (B) at least one predetermined thiol having two or more mercapto groups, (C) an acidic phosphoric acid ester represented by General Formula (1), and (D) a tin compound represented by General Formula (2), in which the acidic phosphoric acid ester (C) is contained in an amount of 0.05 parts by weight to 0.9 parts by weight, with respect to a total of 100 parts by weight of the isocyanates (A) and the thiols (B), and the tin compound (D) is contained in such an amount that the content of tin is 0.05 parts by weight to 0.3 parts by weight, with respect to a total of 100 parts by weight of the isocyanates (A) and the thiols (B).