Polythiourethane Lens Resolving Impact and Thermal Resistance Trade-off
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Solution Overview
Problem
Polythiourethane-based plastic lenses face challenges in achieving both high thermal resistance and impact resistance, with existing compositions often compromising on one property to enhance the other, leading to deformation under heat or distortion over time.
Innovation Solution
A polythiourethane-based plastic lens is developed using a polymerizable composition of bi- or higher-functional polythiol and isocyanate compounds, with specific ratios and molecular weights to achieve a storage modulus ratio of 1 to 10, storage modulus of 100 to 3,000 MPa, energy attenuation of 1 to 50, and a glass transition temperature of 70 to 160°C, enhancing both impact and thermal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the composition is designed to enhance the impact resistance by introducing ester groups into thiol-based compounds, then the impact resistance is improved, but the thermal resistance becomes insufficient causing lens deformation under heat
Solution Approach 1:
The patent changes the chemical composition parameters by introducing specific ester groups (carboxylate ester, sulfate ester, or carbonate ester) into the polythiol compound structure and controlling their content within 1-50 mol% range. This parameter optimization allows the material to achieve both high impact resistance (through the flexible ester groups) and sufficient thermal resistance (by limiting excessive ester content and selecting appropriate glass transition temperature of 70-160°C), resolving the contradiction between impact resistance and thermal resistance
Solution Approach 2:
The patent creates a composite material system by combining polythiol compounds with ester groups and isocyanate compounds to form polythiourethane-based optical materials. This composite approach integrates the flexible ester groups for impact resistance while maintaining the structural integrity and thermal stability through the polythiourethane matrix, achieving both improved impact resistance and adequate thermal resistance simultaneously
2Reliability
If the lens is exposed to high-temperature environmental conditions for a long period, then the focal length becomes distorted, but maintaining thermal resistance may reduce impact resistance
Solution Approach 1:
The patent optimizes the glass transition temperature parameter of the polythiourethane-based optical material to be within 70-160°C, which provides sufficient thermal resistance to prevent focal length distortion under long-term high-temperature exposure. Simultaneously, the controlled ester group content (1-50 mol%) maintains impact resistance by providing molecular flexibility without excessive softening, thus achieving both long-term reliability and impact resistance
Data Source
AI summary
Embodiments relate to a polythiourethane-based plastic lens. When a polythiourethane-based plastic lens is polymerized according to the embodiment, the types, contents, and the like of the polythiol compounds and the isocyanate compounds are adjusted to control the storage moduli at room temperature and high temperatures, their variations, the energy attenuation (KEL) obtained therefrom, and the glass transition temperature, whereby the polythiourethane-based plastic lens thus obtained is enhanced in impact resistance and thermal resistance.