Optical Material Composition Using Hindered Amine Catalyst
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Solution Overview
Problem
Existing optical materials struggle to simultaneously achieve high refractive index, high strength, and high heat resistance, particularly for rimless frame spectacle lenses, due to rapid polymerization and viscosity issues in compositions involving episulfide, inorganic, thiol, and isocyanate compounds.
Innovation Solution
A method using a hindered amine compound as a catalyst for pre-polymerization reaction between an inorganic compound with a sulfur atom, an episulfide compound, a thiol compound, and an isocyanate compound, which results in a less viscous composition that can be cured to achieve a refractive index of 1.73 or higher, high strength, and heat resistance of 70°C or higher.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If pre-polymerization reaction is performed without a hindered amine catalyst, then the composition becomes highly viscous and difficult to cast, but using a hindered amine catalyst enables smooth casting while maintaining high refractive index
Solution Approach 1:
The patent changes the chemical parameter by introducing a hindered amine catalyst (specifically 2,2,6,6-tetramethylpiperidine or 1,2,2,6,6-pentamethylpiperidine) to modify the polymerization kinetics. This catalyst control allows the composition to maintain manageable viscosity during casting while still achieving the target refractive index of 1.73 or higher, resolving the contradiction between castability and viscosity
Solution Approach 2:
The hindered amine catalyst acts as an intermediary substance that mediates between the inorganic compound (sulfur or selenium) and the organic compounds (episulfide, thiol, and isocyanate). It facilitates controlled pre-polymerization reaction, enabling the system to achieve homogeneous mixing and proper curing without excessive viscosity buildup, thus resolving the manufacturing difficulty
2Stability of the object's composition
If thiol compound and isocyanate compound are added to pre-polymerization reaction product, then rapid polymerization occurs making homogeneous material impossible, but avoiding them prevents achieving high strength and heat resistance
Solution Approach 1:
The patent applies preliminary action by performing pre-polymerization reaction between the inorganic compound and episulfide compound first, creating a reactive intermediate composition. This preliminary step allows subsequent addition of thiol and isocyanate compounds to proceed with controlled polymerization rather than rapid polymerization, achieving both homogeneity and high strength
Solution Approach 2:
The patent implements periodic action through a multi-stage process: first pre-polymerization of inorganic compound with episulfide, then addition of thiol and isocyanate compounds, followed by curing. This staged approach controls the polymerization rate, preventing rapid polymerization while ensuring complete reaction for high strength and heat resistance
3Length of moving object
If high refractive index compounds are used to reduce lens thickness, then lens becomes thinner, but strength and heat resistance become insufficient for rimless frames
Solution Approach 1:
The patent creates a composite material system combining inorganic compounds (sulfur or selenium) with organic compounds (episulfide, thiol, and isocyanate). This composite composition achieves high refractive index (1.73 or higher) for thin lens design while the complete polymerization network provides sufficient strength and heat resistance for rimless frame applications
Solution Approach 2:
The patent changes the chemical composition parameters by incorporating 10-50 parts by mass of inorganic compound (sulfur or selenium) into the polymer system. This compositional change achieves the desired refractive index for thin lenses while maintaining mechanical strength and heat resistance through proper catalyst control and complete curing
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 method enables the production of optical materials with a refractive index of 1.73 or higher, elongation of 13% or more in three-point bend test, and heat resistance of 70°C or higher, suitable for rimless frame spectacle lenses, while avoiding rapid polymerization and viscosity issues.
Implementation Method 1
pre-polymerization reaction between an inorganic compound having a sulfur atom, an episulfide compound, a thiol compound, and an isocyanate compound using a hindered amine as a catalyst
Implementation Method 2
polymerizing and curing the resulting composition for optical material
Data Source
AI summary
According to the present invention, a composition for optical material, which is capable of providing a homogeneous optical material, can be prepared through pre-polymerization reaction between (a) an inorganic compound having a sulfur atom and (b) an episulfide compound using a hindered amine as a catalyst, followed by mixing with (c) a polythiol compound and (d) a polyisocyanate compound. Moreover, this composition for optical material can be polymerized and cured to thereby provide an optical material having high refractive index (ne of 1.73 or higher), high strength (an elongation of 13% or more in three-point bend test and good drilling resistance), and high heat resistance (a softening point of 70°C or higher, as measured by TMA).