Liquid Crystalline Polymer Composition for High Heat Deflection
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Solution Overview
Problem
Existing thermotropic liquid crystalline polymers (LCPs) derived from hydroquinone, terephthalic acid, 2,6-naphthalenedicarboxylic acid, and 4-hydroxybenzoic acid have limitations in achieving high heat deflection temperatures, as predicted by existing equations, which restrict their high-temperature applications.
Innovation Solution
A composition comprising 100 molar parts of hydroquinone, 85 to 100 molar parts of 2,6-naphthalenedicarboxylic acid, 0 to 15 molar parts of terephthalic acid, and 50 to 150 molar parts of 4-hydroxybenzoic acid, with specific ratios of 2,6-naphthalenedicarboxylic acid and 4-hydroxybenzoic acid, forming LCPs with unexpectedly higher heat deflection temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If LCPs are made with high amounts of repeat units derived from terephthalic acid (following conventional composition), then the polymer can be manufactured using existing processes, but the heat deflection temperature is limited and lower than desired for high-temperature applications
Solution Approach 1:
The patent applies parameter changes by modifying the molar ratios of monomers in the LCP composition. Specifically, it reduces terephthalic acid content to 0-15 molar parts and increases 4-hydroxybenzoic acid content to 50-150 molar parts while maintaining 100 molar parts of hydroquinone and 85-100 molar parts of 2,6-naphthalenedicarboxylic acid. This compositional parameter change results in heat deflection temperatures approximately 35°C higher than predicted by existing equations, directly resolving the contradiction between achieving high temperature performance and maintaining composition flexibility.
2Temperature
If the molar ratio of 4-hydroxybenzoic acid is increased to achieve higher heat deflection temperature, then the polymer's resistance to bending at high temperature improves, but the polymerization process becomes more challenging to control
Solution Approach 1:
The patent resolves this contradiction by optimizing the molar ratio parameters within specific ranges: 4-hydroxybenzoic acid at 50-150 molar parts (with 75-125 being preferred) and 2,6-naphthalenedicarboxylic acid at 85-100 molar parts (with 85-88 being preferred when 4-hydroxybenzoic acid is at 50-130 molar parts). These parameter ranges achieve heat deflection temperatures approximately 35°C higher than predicted while maintaining acceptable polymerization process control, balancing high-temperature performance with manufacturability.
Data Source
AI summary
Liquid crystalline polymers containing specified ratios of repeat units derived from hydroquinone, 2,6-naphthalenedicarboxylic acid, 4-hydroxybenzoic acid and optionally terephthalic acid have exceptionally high heat distortion temperatures, making especially useful for service at high temperatures. Compositions containing reinforcing agents, especially fibrous or platy reinforcing agents are particularly useful. These polymers and compositions are useful for electrical and electronic connectors, and as films for the electronics industry, and for other uses.