TMCD-CHDM Polyester Composition With Moderate Tg and Melt Processability

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Solution Overview

Problem

Current polyester compositions based on terephthalic acid and cyclohexanedimethanol exhibit rapid crystallization, leading to difficulties in forming amorphous articles, and have deficiencies in properties such as glass transition temperature and impact strength when modified with ethylene glycol, while polymers with 2,2,4,4-tetramethyl-1,3-cyclobutanediol face high inherent viscosities and processing challenges.

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 % cyclohexanedimethanol residues, with specific inherent viscosity and glass transition temperature ranges, allowing for improved processability and enhanced properties like impact strength, chemical resistance, and thermoformability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of moving object

If PCT is modified with ethylene glycol to slow down crystallization rate, then crystallization half-time is improved, but glass transition temperature and impact strength deteriorate

Engineering Contradiction:

Improvecrystallization half-timeVSAvoidimpact strength

Core Design Contradiction:

Duration of action of moving objectVSStrength

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 fundamentally alters the polymer structure to achieve both long crystallization half-time and high impact strength simultaneously, resolving the trade-off between crystallization rate and mechanical properties

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention creates a composite polyester system combining terephthalic acid, cyclohexanedimethanol, and TMCD in specific proportions. This multi-component composite approach allows the material to exhibit synergistic properties: the cyclohexanedimethanol provides structural stability while TMCD contributes to impact resistance and controls crystallization behavior, achieving both long crystallization half-time and high impact strength

Inventive Principle:

Principle #40Composite materials

2Strength

If polymers containing 2,2,4,4-tetramethyl-1,3-cyclobutanediol are used to improve impact strength, then impact strength is improved, but inherent viscosity and processing difficulty increase

Engineering Contradiction:

Improveimpact strengthVSAvoidprocessability

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The patent optimizes the inherent viscosity parameter by controlling the amount of TMCD (1-99 mole %) and adjusting the overall molecular weight through processing conditions. By maintaining inherent viscosity below 1.0 dL/g, the material achieves high impact strength while remaining processable on standard equipment, resolving the contradiction between strength enhancement and manufacturability

Inventive Principle:

Principle #35Parameter changes

3Speed

If PCT is used to achieve rapid crystallization, then crystallization rate is improved, but difficulty in forming amorphous articles increases

Engineering Contradiction:

Improvecrystallization rateVSAvoidformability of amorphous articles

Core Design Contradiction:

SpeedVSEase of manufacture

Solution Approach 1:

The patent inverts the conventional approach by designing a polyester that crystallizes slowly rather than rapidly. By incorporating TMCD which acts as a crystallization inhibitor, the material maintains amorphous structure during processing, enabling easy formation of amorphous articles while still achieving controlled crystallization when desired, thus resolving the contradiction between crystallization rate and formability

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentUS8101705B2Polyester compositions containing cyclobutanediol having a certain combination of inherent viscosity and moderate glass transition temperature and articles made therefrom

Publication Date: 2012.01.24 EASTMAN CHEM CO

AI summary

Described are articles, comprising polyester based composition, comprising dicarboxylic acid component as terephthalic acid residues and optionally, aromatic dicarboxylic acid residues or aliphatic dicarboxylic acid residues and glycol component, comprising 2,2,4,4-tetramethyl-1,3-cyclobutanediol residues and cyclohexanedimethanol residues. The polyester composition has the inherent viscosity from 0.60 to 0.75 dL/g as determined in 60/40 (wt/wt) phenol/tetrachloroethane at a concentration of 0.5 g/100 ml at 25° C., glass transition temperature Tg of 100° C. to 130° C., notched Izod impact strength of at least 7.5 ft-lb/inch at 23° C. according to ASTM D256 with a 10-mil notch in a ⅛-inch thick bar, melt viscosity is less than 10,000 poise as measured at 1 radian/second on a rotary melt rheometer at 290° C. and does not contain polycarbonate. Composition can be manufactured into articles as fibers, films, bottles or sheets.