Polyester compositions containing cyclobutanediol having a certain combination of inherent viscosity and moderate glass transition temperature and articles made therefrom
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Solution Overview
Problem
Current polyester compositions, such as poly(1,4-cyclohexylenedimethylene terephthalate) and polycarbonates, face challenges in achieving a balance of high impact strength, moderate glass transition temperature, chemical resistance, and processability while maintaining thermoformability and avoiding rapid crystallization, which limits their application in forming amorphous articles.
Innovation Solution
A polyester composition comprising terephthalic acid, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, and 1,4-cyclohexanedimethanol with specific mole percentages and inherent viscosities, allowing for a unique combination of properties like high impact strength, heat resistance, and low ductile-to-brittle transition temperatures, while being processable on standard equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If PCT polyester is used to achieve high impact strength and chemical resistance, then these properties are improved, but the crystallization rate becomes too rapid making it difficult to form amorphous articles
Solution Approach 1:
The patent modifies the crystallization rate by changing the chemical composition parameters of the polyester, specifically incorporating cyclobutanediol units which alter the polymer chain structure and reduce crystallization tendency, allowing amorphous articles to be formed while maintaining impact strength
Solution Approach 2:
The invention creates a copolyester composite combining terephthalic acid units with cyclobutanediol units, where the cyclobutanediol component acts as a crystallization inhibitor while the terephthalic acid provides mechanical strength and chemical resistance
2Productivity
If ethylene glycol or isophthalic acid is added to slow down crystallization, then crystallization half-time is improved, but glass transition temperature decreases and impact strength is reduced
Solution Approach 1:
The patent changes the chemical composition by substituting ethylene glycol or isophthalic acid modifiers with cyclobutanediol units, which achieve crystallization control while maintaining or improving glass transition temperature and impact strength through different molecular mechanisms
3Productivity
If 2,2,4,4-tetramethyl-1,3-cyclobutanediol is used to control crystallization, then crystallization half-time is improved, but inherent viscosity and melt viscosity become too high for standard equipment processing
Solution Approach 1:
The patent optimizes the concentration parameter of cyclobutanediol units to achieve a balance where sufficient crystallization control is obtained while keeping the inherent viscosity and melt viscosity within ranges suitable for standard processing equipment
Solution Approach 2:
The invention introduces cyclobutanediol units at specific local concentrations within the polymer chain rather than uniform distribution, allowing crystallization control in specific regions while maintaining overall processability
Data Source
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AI summary
Described are polyesters comprising (a) a dicarboxylic acid component comprising terephthalic acid residues; optionally, aromatic dicarboxylic acid residues or aliphatic dicarboxylic acid residues; 2,2,4,4-tetramethyl-1,3-cyclobutanediol residues; and 1,4-cyclohexanedimethanol residues. The polyesters may be manufactured into articles such as fibers, films, bottles or sheets.