Cyclobutanediol Copolyester Containers for Heat-Resistant Impact Strength

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Solution Overview

Problem

Current plastic materials for containers, such as PET and polycarbonate, face challenges with high-heat applications due to poor barrier properties and processing difficulties, leading to a need for materials with high impact strength, heat resistance, and processability that can maintain performance at elevated temperatures.

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, which provides high impact strength, heat resistance, and processability, while maintaining chemical resistance and clarity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If PET is used for containers, then it provides good barrier properties, but it becomes difficult to use at elevated temperatures such as during pasteurization or retort applications

Engineering Contradiction:

Improvebarrier propertiesVSAvoidheat resistance

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The patent uses a copolyester composition combining three different glycols (ethylene glycol, 1,4-cyclohexanedimethanol, and 1,3-propanediol) with terephthalic acid to create a composite material that integrates the heat resistance of PCT with the processability and barrier properties of PET, achieving both high-temperature stability and functional performance

Inventive Principle:

Principle #40Composite materials

2Temperature

If higher temperature materials such as polycarbonate or acrylic polymers are used, then heat resistance is improved, but barrier properties become poor

Engineering Contradiction:

Improveheat resistanceVSAvoidbarrier properties

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The copolyester composition integrates multiple glycol components to combine the heat resistance characteristics of polycarbonate-like structures with the barrier properties of polyester, achieving a material that simultaneously provides both high-temperature stability and effective barrier performance

Inventive Principle:

Principle #40Composite materials

3Temperature

If PCT is used, then heat resistance is improved, but it crystallizes rapidly upon cooling making it very difficult to form amorphous articles

Engineering Contradiction:

Improveheat resistanceVSAvoidprocessability

Core Design Contradiction:

TemperatureVSEase of manufacture

Solution Approach 1:

The patent introduces three different glycol components with varying chain lengths and structures into the polyester backbone, creating local compositional variations that disrupt crystallization kinetics and enable amorphous article formation while preserving heat resistance

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent modifies the compositional parameters of the polyester by incorporating multiple glycols in specific ratios, changing the crystallization behavior from rapid (PCT) to controlled or suppressed, thereby enabling amorphous article formation through standard processing methods

Inventive Principle:

Principle #35Parameter changes

4Ease of manufacture

If copolyesters containing ethylene glycol or isophthalic acid are used to slow crystallization, then crystallization rate is reduced, but glass transition temperature and impact strength deteriorate

Engineering Contradiction:

Improvecrystallization controlVSAvoidimpact strength

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The patent carefully controls the compositional parameters by selecting three specific glycols and defining their mole percentage ranges, optimizing the balance between crystallization control and mechanical property preservation, thereby achieving slow crystallization without sacrificing impact strength

Inventive Principle:

Principle #35Parameter changes

5Ease of manufacture

If sufficient modifying 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 formationVSAvoidglass transition temperature

Core Design Contradiction:

Ease of manufactureVSTemperature

Solution Approach 1:

The patent uses three different glycol components with distinct molecular characteristics to create local compositional heterogeneity that facilitates amorphous formation while maintaining overall thermal stability, avoiding the temperature degradation associated with single-glycol modifications

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS8354491B2Containers comprising polyester compositions which comprise cyclobutanediol

Publication Date: 2013.01.15 EASTMAN CHEM CO

AI summary

Described are container(s) comprising polyesters comprising (a) a dicarboxylic acid component comprising terephthalic acid residues; optionally, aromatic dicarboxylic acid or aliphatic dicarboxylic acid residues; and (b) a glycol component comprising 15 to 50 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol residues and 50 to 85 mole % 1,4-cyclohexanedimethanol residues; wherein the total mole % of said dicarboxylic acid component is 100 mole %, and the total mole % of said glycol component is 100 mole %;wherein the inherent viscosity of the polyester is from 0.50 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.;wherein said polyester has a 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 1/8-inch thick bar; and wherein the melt viscosity of said polyester is less than 10,000 poise as measured at 1 radian/second on a rotary melt rheometer at 290° C.