Ternary Polyester Blend Haze Reduction via Compatibilizer

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Solution Overview

Problem

Blends of PETG and PCTT polyesters typically exhibit unacceptable haze due to immiscibility and different refractive indices, limiting their application in extruded films.

Innovation Solution

A ternary polyester blend comprising PCTT, PETG, and PCTG, with specific mole percentages of terephthalic acid and 1,4-cyclohexanedimethanol derivatives, is developed to achieve miscibility and reduce haze to 5% or less in extruded films.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If PETG and PCTT polyesters are blended, then the blend exhibits improved adhesion and lowered viscosity for extrusion processing, but the blend shows unacceptable haze due to immiscibility and different refractive indices

Engineering Contradiction:

Improveextrusion processingVSAvoidhaze

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a compatibilizer polyester containing both CHDM and TMCD moieties as an intermediary substance between PETG and PCTT. This compatibilizer has refractive index and polarity characteristics intermediate between the two immiscible polymers, enabling it to act as a molecular bridge that reduces interfacial tension and promotes miscibility, thereby eliminating haze while preserving the adhesion and processability benefits of the PETG-PCTT blend

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent systematically adjusts the composition parameters of the ternary blend, specifically controlling the weight percentages of PETG (5-20%), PCTT (60-80%), and compatibilizer (10-30%). By optimizing these compositional parameters and the diol component ratios, the blend achieves a critical miscibility threshold that eliminates haze formation while maintaining the desired processing characteristics

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If PETG copolyester is used in blends to improve adhesion and lower viscosity, then processing properties are enhanced, but miscibility with PCTT copolyester is lost

Engineering Contradiction:

Improveadhesion and viscosityVSAvoidmiscibility

Core Design Contradiction:

Ease of manufactureVSStability of the object's composition

Solution Approach 1:

The patent creates a composite polyester system where the compatibilizer component functions as a molecular bridge containing both CHDM and TMCD moieties in specific ratios. This composite structure combines the adhesive properties from PETG's glycol composition with the processability benefits from PCTT's cyclobutane content, while the intermediate polarity and refractive index of the compatibilizer ensure thermodynamic miscibility of the entire ternary system

Inventive Principle:

Principle #40Composite materials

Data Source

PatentEP2870201B1Ternary blends of terephthalate or isophthalate polyesters containing eg, CHDM, and tmcd

Publication Date: 2018.08.22 EASTMAN CHEM CO

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AI summary

Disclosed are ternary polyester blends that contain at least one polyester comprising terephthalic or isophthalic acid, ethylene glycol, and 1,4- cyclohexanedimethanol residues, and at least one polyester comprising terephthalic or isophthalic acid, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, and 1,4-cyclohexanedimethanol residues. The ternary polyester blends have improved clarity, toughness, and fabrication characteristics and are useful for the preparation of flat or shaped articles. Of special interest are ternary blends where one of the three components compatibilizes the blend of two otherwise immiscible polyesters.