Polymerizable Compound for High Refractive Index Optical Resins
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Solution Overview
Problem
Current optical resins fail to achieve a high refractive index exceeding 1.7 while maintaining transparency, thermal properties, and mechanical strength, which are essential for advanced plastic lenses.
Innovation Solution
A polymerizable compound comprising one or more thietane groups and a metal atom, such as Sn, Si, or Ge, is developed, which upon polymerization forms a resin with enhanced refractive index, transparency, and mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional optical resins (DAC-based crosslinking type) are used, then transparency and heat resistance are excellent, but refractive index is low (nd=1.50) resulting in large lens thickness
Solution Approach 1:
The patent introduces a composite resin system combining polythiourethane base resin with polymerizable compounds containing high refractive index groups (episulfide, selenide, metal carboxylates). This composite approach achieves refractive index exceeding 1.7 while preserving the excellent transparency and heat resistance of the polythiourethane matrix, solving the contradiction between maintaining thermal properties and achieving high refractive index.
2Strength
If polythiourethane is used, then transparency and impact resistance are excellent with high refractive index (nd=1.6 to 1.7), but lens thickness remains large for general-purpose applications
Solution Approach 1:
The patent systematically varies the refractive index contribution by changing the type and content of polymerizable compounds (episulfide 0.1-10 wt%, selenide 0.1-5 wt%, metal carboxylates 1-50 wt%). This parameter adjustment enables fine-tuning of the final refractive index above 1.7 while preserving the impact resistance inherent in the polythiourethane structure, resolving the contradiction between strength and refractive index.
3Stability of the object's composition
If compounds with episulfide groups are polymerized, then refractive index increases, but mechanical properties deteriorate
Solution Approach 1:
The patent creates a composite system where episulfide-containing polymerizable compounds (providing high refractive index) are incorporated into a polythiourethane matrix (providing mechanical strength). The synergistic combination allows the resin to achieve refractive index above 1.7 while the polythiourethane base maintains excellent mechanical properties, resolving the contradiction between refractive index and mechanical strength.
Solution Approach 2:
The patent distributes the episulfide groups locally within the polymer matrix rather than using them as the bulk material. This localized incorporation (0.1-10 wt%) allows the high refractive index function to be achieved in specific regions while the majority of the matrix retains the mechanical properties of polythiourethane, resolving the contradiction between local refractive index enhancement and overall mechanical strength.
4Stability of the object's composition
If Se-containing metal compounds are used, then refractive index increases, but safety problems arise
Solution Approach 1:
The patent employs metal carboxylate compounds (such as tin, zinc, calcium carboxylates) as temporary refractive index enhancers during the polymerization process. These metal-containing polymerizable compounds serve their purpose of boosting refractive index above 1.7, and any residual metal compounds are present in minimal amounts in the final cured resin, significantly reducing safety concerns compared to Se-containing compounds.
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 resulting resin exhibits high transparency, good heat resistance, and mechanical strength, making it suitable for high-quality plastic lenses with a refractive index exceeding 1.7.
Implementation Method 1
a compound comprising one or two or more thietane groups and a metal atom in a molecule, while attaining a very high refractive index
Implementation Method 2
a resin obtained by polymerization of the polymerizable composition
Data Source
AI summary
The present invention is to provide a polymerizable compound which can be a raw material for a resin having high transparency, good heat resistance and mechanical strength required for optical components such as plastic lenses and the like, while attaining a high refractive index (nd) exceeding 1.7, and an optical component composed of such a resin.Disclosed is a compound represented by the general formula (3),wherein, in the formula, M represents a metal atom; X1 and X2 each independently represent a sulfur atom or an oxygen atom; R1 represents a divalent organic group; m represents an integer of 0 or 1 or more; p represents an integer of from 1 to n; q represents an integer of from 1 to (n-p); n represents a valence of a metal atom M; Yq each independently represent an inorganic or organic residue; and when q is 2 or more, Yq may be bonded to one another for forming a ring structure with the intermediary of a metal atom M.