Polyester Film Composition With TMCD for Slow Crystallization

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Solution Overview

Problem

Current polyester compositions, such as poly(1,4-cyclohexylenedimethylene terephthalate and ethylene glycol-modified PCTs, face challenges in achieving a balance of high impact strength, glass transition temperature, and processability while maintaining thermoformability and chemical resistance, with issues like rapid crystallization and high melt viscosity.

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, that allows for the production of films and sheets with improved impact strength, chemical resistance, and thermoformability, eliminating the need for a drying step prior to processing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of time

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

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) and adjusting the molar ratios of components. This substitution maintains extended crystallization half-time while improving impact strength and glass transition temperature through the unique molecular structure of TMCD

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite polyester formulation combining terephthalic acid, 1,4-cyclohexanedimethanol, and 2,2,4,4-tetramethyl-1,3-cyclobutanediol in specific proportions. This composite approach achieves synergistic effects where the combination of components provides both slow crystallization rate and enhanced mechanical properties

Inventive Principle:

Principle #40Composite materials

2Loss of time

If 2,2,4,4-tetramethyl-1,3-cyclobutanediol is used to extend crystallization half-time, then crystallization rate is reduced, but inherent viscosity and melt viscosity increase excessively

Engineering Contradiction:

Improvecrystallization half-timeVSAvoidprocessability

Core Design Contradiction:

Loss of timeVSEase of manufacture

Solution Approach 1:

The patent optimizes the concentration parameter of TMCD within a specific range (30-70 mol%) and controls the inherent viscosity to be between 0.20-0.60 dL/g. By precisely adjusting these parameters, the formulation achieves extended crystallization half-time while maintaining acceptable melt flow characteristics for industrial processing

Inventive Principle:

Principle #35Parameter changes

3Shape

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 chemical resistance deteriorates

Engineering Contradiction:

Improveamorphous structureVSAvoidchemical resistance

Core Design Contradiction:

ShapeVSReliability

Solution Approach 1:

The patent changes the chemical composition by substituting ethylene glycol with TMCD and 1,4-cyclohexanedimethanol, achieving amorphous structure formation with improved chemical resistance. The specific molar ratios and viscosity control enable amorphous product formation while enhancing hydrolytic stability and chemical resistance

Inventive Principle:

Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The resulting films and sheets exhibit superior properties like high impact strength, hydrolytic stability, and good color and clarity, with reduced ductile-to-brittle transition temperatures and lower specific gravity, while being processable on standard industry equipment, enabling the production of amorphous or semicrystalline articles with long crystallization half-times.

Implementation Method 1

This polyester crystallizes rapidly upon cooling from the melt, making it very difficult to form amorphous articles by methods known in the art

Methodology Applied

Scientific EffectCrystallization: Crystallisation

Data Source

PatentEP1910442B1Film(s) and/or sheet(s) made from polyester compositions containing cyclobutanediol and articles made therefrom

Publication Date: 2010.05.05 EASTMAN CHEM CO

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AI summary

Described are film(s) and/or sheet(s) made using polyester compositions comprising polyesters containing (a) a dicarboxylic acid component having from about 70 to 100 mole % of terephthalic acid residues, and up to about 30 mole% of aromatic dicarboxylic acid or aliphatic dicarboxylic acid residues; and (b) a glycol component comprising 2,2,4,4-tetramethyl-1,3-cyclobutanediol, and 1 ,4-cyclohexanedimethanol.