Amorphous Thermoplastic Polyester for Optical Articles
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Solution Overview
Problem
Current thermoplastic polyesters, particularly those containing 1,4:3,6-dianhydrohexitol units, face limitations in impact resistance and glass transition temperature, making them unsuitable for certain applications, especially in the manufacturing of optical articles which require high thermal resistance, impact resistance, and low birefringence.
Innovation Solution
An amorphous thermoplastic polyester is developed, comprising at least one 1,4:3,6-dianhydrohexitol unit, an alicyclic diol other than 1,4:3,6-dianhydrohexitol, and terephthalic acid, with a specific molar ratio and reduced viscosity, eliminating non-cyclic aliphatic diol units to achieve improved mechanical and optical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If 1,4:3,6-dianhydrohexitol units are introduced into polyester to improve thermal resistance, then glass transition temperature increases, but impact resistance becomes insufficient
Solution Approach 1:
The patent combines 1,4:3,6-dianhydrohexitol units (for high glass transition temperature) with cyclohexanedimethanol units (for impact resistance) in a copolymer structure. This merging of different monomer units allows the material to simultaneously achieve both high thermal resistance and excellent impact resistance, resolving the contradiction between these two properties.
Solution Approach 2:
The invention creates a composite polyester material containing multiple types of monomeric units (1,4:3,6-dianhydrohexitol, cyclohexanedimethanol, and optionally ethylene glycol) in specific proportions. This composite structure integrates the advantageous properties of each component, achieving both high glass transition temperature (116-200°C) and superior impact resistance.
2Reliability
If polycondensation temperature is limited to 270°C to avoid thermal degradation, then thermal degradation is reduced, but polyester viscosity remains limited
Solution Approach 1:
The patent changes the chemical composition parameters of the polyester by incorporating specific monomer units (1,4:3,6-dianhydrohexitol and cyclohexanedimethanol) in optimized ratios. This compositional parameter change allows the material to achieve high viscosity (>50 mL/g) without requiring excessive polycondensation temperatures, thus avoiding thermal degradation while maintaining desired rheological properties.
Solution Approach 2:
The invention introduces specific functional groups and molecular structures (the 1,4:3,6-dianhydrohexitol and cyclohexanedimethanol units) at specific concentrations (1-60 mol% and 5-99% respectively) to locally enhance the polymer chain interactions and viscosity, allowing controlled viscosity enhancement without global thermal degradation.
3Strength
If amorphous structure is achieved to improve impact resistance, then crystallinity is reduced, but manufacturing precision for optical articles becomes challenging
Solution Approach 1:
The patent precisely controls the compositional parameters (molar ratios of different diol units) and processing parameters (temperature range 116-200°C) to achieve an amorphous structure with specific physical properties. This controlled parameter optimization ensures that the amorphous polyester exhibits both high impact resistance and suitable manufacturing characteristics for optical articles, including appropriate viscosity and optical clarity.
Data Source
Figure 1A~1B
AI summary
The invention relates to the use of an amorphous thermoplastic polyester for the production of optical articles, said thermoplastic polyester having at least one 1,4:3,6-dianhydrohexitol unit (A), at least one alicyclic diol unit (B) other than the 1,4:3,6-dianhydrohexitol units (A), at least one terephthalic acid unit (C), the molar ratio (A)/[(A) + (B)] being at least 0.32 and at most 0.90, said polyester being free of non-cyclic aliphatic diol units or comprising a molar amount of non-cyclic aliphatic diol units, relative to the total monomeric units in the polyester, of less than 5%, and with a reduced viscosity in solution (25°C; phenol (50 wt.%): ortho-dichlorobenzene (50 wt.%); 5 g/L of polyester) greater than 50 mL/g.