Copolyesterimides with Bis(2-hydroxyalkyl) Comonomer for Heat Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing polyesters face challenges in achieving high glass transition temperatures (Tg) without significantly increasing crystalline melting points (Tm) or decreasing degree of crystallinity, which affects their melt-processibility and thermo-mechanical stability, especially in economic processing conditions below 320°C.
Innovation Solution
Incorporation of the comonomer bis(2-hydroxyalkyl)-2,2′-(1,4-phenylene)bis(1,3-dioxoisoindoline-5-carboxylate) into poly(alkylene terephthalate) and poly(alkylene naphthalate) copolymers, which increases Tg without substantially raising Tm or reducing crystallinity, allowing for the production of semi-crystalline copolyesters with improved heat-resistance and thermo-mechanical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If more rigid comonomers are introduced to enhance glass transition temperature, then Tg increases, but Tm and degree of crystallinity decrease
Solution Approach 1:
The patent applies parameter changes by carefully controlling the composition ratio of rigid comonomer (1,4-naphthalenedicarboxylic acid) to achieve optimal Tg enhancement while preserving crystallinity. By adjusting the molar ratio parameters within specific ranges, the patent resolves the contradiction between increasing Tg and maintaining degree of crystallinity above 30%.
Solution Approach 2:
The patent creates a composite polyester structure combining rigid 1,4-naphthalenedicarboxylic acid units with other aromatic carboxylic acid units. This composite approach allows the rigid segments to elevate Tg while the overall copolymer structure maintains sufficient crystallinity through controlled phase separation and regular packing of crystalline regions.
2Temperature
If Tm is increased to improve thermo-mechanical stability, then heat-resistance improves, but melt-processibility deteriorates
Solution Approach 1:
The patent optimizes the Tm parameter by controlling the copolymer composition and crystallinity degree. By maintaining Tm within the range of 220-280°C through precise monomer ratio adjustment, the patent achieves both improved heat-resistance and preserved melt-processibility, avoiding the need for expensive high-temperature processing equipment.
3Temperature
If comonomers are introduced to increase Tg while retaining Tm, then Tg increases, but decomposition temperature converges with Tm leading to degradation
Solution Approach 1:
The patent carefully controls the composition parameters and processing conditions to maintain a sufficient temperature gap between Tm and decomposition temperature. By optimizing the copolymer structure and limiting comonomer content to specific ranges, the patent prevents degradation while achieving Tg enhancement, ensuring reliable processing and product performance.
Data Source
AI summary
Disclosed herein are film, fiber, molding composition and molded article including copolyesters that exhibit improved heat-resistance and thermo-mechanical stability. The copolyester is derived from an aliphatic glycol, an aromatic dicarboxylic acid selected from naphthalene dicarboxylic acid and terephthalic acid, and 5-50 mol % (based on 100 mole % of all glycols) of an additional monomer, bis(2-hydroxyalkyl)-2,2′-(1,4-phenylene)bis(1,3-dioxoisoindoline-5-carboxylate). The aromatic dicarboxylic acid is at least one of naphthalene dicarboxylic acid and terephthalic acid and the aliphatic glycol is selected from C2, C3 or C4 aliphatic diols. Furthermore, the copolyesters have crystallinity of at least 10%.