Polycarbonate Copolymer for Optical Lenses Balancing Refractive Index and Abbe Number
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Solution Overview
Problem
There is a need for a resin for optical lenses that balances refractive index and Abbe number, while also excelling in heat resistance, total light transmittance, and hue, as existing materials face challenges in these areas.
Innovation Solution
A polycarbonate is developed by copolymerizing dispiroglycol (DSG) with a dihydroxy compound having a hydrocarbon group containing a cyclic structure, specifically incorporating a constituent unit represented by Formula [I] and another with a hydrocarbon group containing a cyclic structure, to achieve the desired properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If optical glass is used for optical lenses, then heat resistance, transparency, dimensional stability, and chemical resistance are improved, but material costs increase, molding processability deteriorates, and productivity decreases
Solution Approach 1:
The patent modifies the chemical composition parameters of the polycarbonate by incorporating specific dihydroxy compounds (cyclic structures at 10-50 mol%) to achieve optimal balance between heat resistance (Tg ≥ 100°C) and injection molding processability, resolving the contradiction between material performance and manufacturability
Solution Approach 2:
The patent creates a composite polycarbonate system combining multiple dihydroxy compound types (cyclic and non-cyclic) with specific molecular weight ranges, achieving synergistic effects that provide both high heat resistance and excellent molding processability, unlike conventional single-component polycarbonates
2Weight of moving object
If polycarbonate with high refractive index is used, then lens thickness can be made thinner and weight reduced, but Abbe number decreases causing chromatic aberration
Solution Approach 1:
The patent optimizes the refractive index to 1.58-1.65 and Abbe number to 30-38 by adjusting the ratio of cyclic to non-cyclic dihydroxy compounds, achieving a balanced optical performance that reduces chromatic aberration while maintaining thin lens design
Solution Approach 2:
The patent introduces cyclic hydrocarbon groups at specific proportions (10-50 mol%) to locally modify the polymer chain structure, enhancing light dispersion properties and reducing chromatic aberration in specific regions of the lens material
3Reliability
If polycarbonate with high Abbe number is used, then chromatic aberration is reduced, but refractive index decreases requiring thicker lenses
Solution Approach 1:
The patent simultaneously optimizes both Abbe number (30-38) and refractive index (1.58-1.65) through controlled copolymerization of cyclic and non-cyclic dihydroxy compounds, achieving a balanced optical performance that satisfies both chromatic aberration correction and thin lens requirements
Data Source
AI summary
Provided are a polycarbonate having an appropriate refractive index and an appropriate Abbe number, and comprehensively excelling in heat resistance, total light transmittance, and hue, and a molded article thereof. The polycarbonate includes a constituent unit represented by Formula [I] and a constituent unit having a hydrocarbon group containing a cyclic structure. In Formula [I], R1 and R2 each independently denote a hydrocarbon group, and each R3 independently denotes a hydrogen atom, a heteroatom-containing group, a halogen atom-containing group, a linear alkyl group having from 1 to 6 carbon atoms, a branched alkyl group having from 3 to 6 carbon atoms, or a group including an aryl group and having from 6 to 12 carbon atoms.