TMCD Polyester Composition for High Tg and Slow Crystallization

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Solution Overview

Problem

Current polyester compositions based on terephthalic acid, 1,4-cyclohexanedimethanol, and ethylene glycol exhibit deficiencies in glass transition temperature and impact strength, with rapid crystallization making it difficult to form amorphous articles, and existing polycarbonates have poor chemical resistance and melt processability.

Innovation Solution

A polyester composition comprising 70 to 100 mole % terephthalic acid residues, 0 to 30 mole % aromatic dicarboxylic acid residues, 0 to 10 mole % aliphatic dicarboxylic acid residues, 1 to 99 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol residues, and 1 to 99 mole % 1,4-cyclohexanedimethanol residues, with specific inherent viscosity and glass transition temperature ranges, allowing for high impact strength, hydrolytic stability, and thermoformability while maintaining processability on standard equipment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of time

If ethylene glycol is added to PCT copolyester to slow down crystallization rate, then crystallization half-time is extended, but glass transition temperature and impact strength decrease

Engineering Contradiction:

Improvecrystallization half-timeVSAvoidimpact strength

Core Design Contradiction:

Loss of timeVSStrength

Solution Approach 1:

The patent changes the chemical composition parameters by replacing ethylene glycol with 2,2,4,4-tetramethyl-1,3-cyclobutanediol (TMCD), which has different molecular structure and properties. This substitution alters the polymer chain flexibility and intermolecular forces, achieving extended crystallization half-time while maintaining or improving impact strength and glass transition temperature.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite polyester system combining terephthalic acid, 1,4-cyclohexanedimethanol, and 2,2,4,4-tetramethyl-1,3-cyclobutanediol in specific ratios. This composite approach allows synergistic effects where the cyclobutanediol component provides both crystallization control and mechanical property enhancement that neither component achieves alone.

Inventive Principle:

Principle #40Composite materials

2Stability of the object's composition

If sufficient ethylene glycol is included to provide long crystallization half-times, then amorphous products can be formed, but ductile-to-brittle transition temperature increases and glass transition temperature decreases

Engineering Contradiction:

Improveamorphous product formationVSAvoidglass transition temperature

Core Design Contradiction:

Stability of the object's compositionVSTemperature

Solution Approach 1:

The patent modifies the compositional parameters by substituting ethylene glycol with TMCD, which changes the polymer's thermal transitions. The cyclobutanediol unit introduces rigid cyclic structures that elevate glass transition temperature while still allowing sufficient chain mobility for amorphous product formation during processing.

Inventive Principle:

Principle #35Parameter changes

3Strength

If polycarbonate is used as alternative to polyester, then heat resistance and impact strength improve, but chemical resistance and melt processability deteriorate

Engineering Contradiction:

Improveimpact strengthVSAvoidmelt processability

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The patent changes the chemical structure from polycarbonate (with aromatic rings and carbonate groups) to polyester containing cyclobutanediol units. This structural transformation reduces melt viscosity and improves processability while the cyclic aliphatic structure maintains heat resistance comparable to polycarbonate.

Inventive Principle:

Principle #35Parameter changes

4Strength

If 2,2,4,4-tetramethyl-1,3-cyclobutanediol is used in polyester, then impact strength and heat resistance improve, but inherent viscosity and melt viscosity increase

Engineering Contradiction:

Improveimpact strengthVSAvoidmelt viscosity

Core Design Contradiction:

StrengthVSForce

Solution Approach 1:

The patent optimizes the concentration parameter of TMCD within specific ranges (1-99 mole%) to balance viscosity and mechanical properties. Additionally, the patent controls molecular weight and polydispersity to manage inherent viscosity while maximizing impact strength benefits from the cyclobutanediol structure.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS9765181B2Polyester compositions containing cyclobutanediol having a certain combination of inherent viscosity and high glass transition temperature and articles made therefrom

Publication Date: 2017.09.19 EASTMAN CHEM CO

AI summary

Described are coating compositions comprising a polyester, the polyester comprising: at least one polyester which comprises a dicarboxylic acid component comprising terephthalic acid residues, and a glycol component comprising 30 to 40 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol residues and 60 to 70 mole % cyclohexanedimethanol residues, where the inherent viscosity of the polyester is from 0.10 to 0.70 dL/g, and where the coating composition is made from a film or sheet.