Copolycarbonate Lenses with Organosulfonic Stabilizer
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Solution Overview
Problem
There is a need for polycarbonate lenses with improved balance of high heat performance and optical properties, as existing high heat copolycarbonates often yellow and have lower transmission values after processing.
Innovation Solution
A polycarbonate composition comprising bisphenol A carbonate units, second carbonate units, and an organosulfonic stabilizer, which maintains high glass transition temperature and optical clarity even under aggressive molding conditions, with specific formulations and processing methods to ensure low residual impurities and optimal molecular weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If high heat copolycarbonates are used to achieve high glass transition temperatures of 150°C or higher, then heat resistance is improved, but the material becomes more yellow after processing and has lower transmission values
Solution Approach 1:
The patent modifies the chemical structure of carbonate units by introducing specific alkyl, alkenyl, cycloalkyl, or alkoxy groups at defined positions (Ra, Rb, R3, R4) with controlled substitution patterns (p, q, j values). This structural parameter change allows achieving high glass transition temperature (150°C or higher) while maintaining optical clarity and reducing yellowness, directly resolving the contradiction between heat resistance and optical properties
Solution Approach 2:
The invention creates a copolycarbonate composite material combining bisphenol A carbonate units with modified carbonate units containing specific hydrocarbon groups. This composite structure integrates the heat resistance of bisphenol A polycarbonate with the optical stability of the modified carbonate units, achieving both high glass transition temperature and low yellowness simultaneously
Data Source
AI summary
A lens containing a polycarbonate composition is disclosed. The polycarbonate composition includes a copolycarbonate having bisphenol A carbonate units and second carbonate units of the formulaand 2 to 40 ppm of an organosulfonic stabilizer of the formulawherein the second carbonate units are present in an amount of 20 to 49 mol %, preferably 30 to 40 mol % based on the sum of the moles of the copolycarbonate and the bisphenol A homopolycarbonate. The polycarbonate composition has: a Vicat B120 of 160° C. or higher measured according to ISO 306; and a yellowness index of less than 12, measured according to ASTM D1925.