Cyclobutanediol Polyester Composition for Amorphous Thermoforming

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Solution Overview

Problem

Current polyester compositions, such as poly(1,4-cyclohexylenedimethylene terephthalate) and bisphenol A polycarbonate, face challenges in achieving a balance of high impact strength, moderate glass transition temperature, chemical resistance, and processability while maintaining thermoformability and avoiding rapid crystallization, which limits their application in forming amorphous articles.

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, allowing for a range of glass transition temperatures and crystallization half-times, enhancing impact strength, chemical resistance, and processability on standard equipment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If PCT crystallizes rapidly upon cooling from the melt, then high crystallization rate is achieved, but it becomes very difficult to form amorphous articles by extrusion, injection molding, and the like

Engineering Contradiction:

Improvecrystallization rateVSAvoidformability of amorphous articles

Core Design Contradiction:

ProductivityVSEase of manufacture

Solution Approach 1:

The patent modifies the crystallization behavior by changing the chemical composition parameters of the polyester, specifically incorporating cyclobutanediol units which alter the crystallization kinetics and enable amorphous article formation while maintaining controlled crystallization properties

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention creates a composite polyester structure by combining terephthalic acid, cyclohexanedimethanol, and cyclobutanediol units, forming a copolyester that exhibits both amorphous and crystalline phases with tailored properties for manufacturability

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If sufficient modifying ethylene glycol is included in the formulation to provide long crystallization half-times, then amorphous products can be formed, but the glass transition temperature becomes undesirably lower and impact strength decreases

Engineering Contradiction:

Improvecrystallization half-timeVSAvoidimpact strength

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The patent changes the chemical composition by replacing ethylene glycol with cyclobutanediol units, which maintains long crystallization half-times for amorphous product formation while preserving higher glass transition temperature and impact strength properties

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention uses a specific molar ratio of cyclobutanediol (5-50 mole%) that provides sufficient modification for processability without excessive amounts that would degrade mechanical properties, optimizing the balance between manufacturability and performance

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Strength

If 2,2,4,4-tetramethyl-1,3-cyclobutanediol is used to improve impact strength and chemical resistance, then high inherent viscosity and high glass transition temperature are achieved, but standard industry equipment becomes insufficient for manufacturing

Engineering Contradiction:

Improveimpact strengthVSAvoidprocessability on standard equipment

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The patent optimizes the inherent viscosity parameter by controlling the cyclobutanediol content at 5-50 mole%, which maintains high impact strength and chemical resistance while reducing viscosity to levels processable on standard industry equipment

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention introduces local structural modification by incorporating cyclobutanediol units at specific concentrations within the polyester chain, providing enhanced mechanical and chemical properties at targeted locations without compromising overall processability

Inventive Principle:

Principle #3Local quality

4Temperature

If bisphenol A polycarbonate is used as an alternative, then high heat resistance and good impact strength are achieved, but relatively high melt viscosity leads to poor melt processability and poor chemical resistance

Engineering Contradiction:

Improveheat resistanceVSAvoidmelt processability

Core Design Contradiction:

TemperatureVSEase of manufacture

Solution Approach 1:

The patent changes the chemical structure from polycarbonate to polyester containing cyclobutanediol units, which maintains heat resistance and impact strength while significantly improving melt processability and chemical resistance through reduced melt viscosity

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention extracts the beneficial properties (impact strength, heat resistance) from bisphenol A polycarbonate and replicates them in a polyester system using cyclobutanediol units, while eliminating the harmful property of high melt viscosity that limits processability

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentEP2277935B1Polyester compositions containing cyclobutanediol having a certain combination of inherent viscosity and moderate glass transition temperature and articles made therefrom

Publication Date: 2015.07.15 EASTMAN CHEM CO

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AI summary

Described are polyesters comprising (a) a dicarboxylic acid component comprising terephthalic acid residues; optionally, aromatic dicarboxylic acid residues or aliphatic dicarboxylic acid residues; 2,2,4,4-tetramethyl-1,3-cyclobutanediol residues; and 1,4-cyclohexanedimethanol residues. The polyesters may be manufactured into articles such as fibers, films, bottles or sheets.