Cyclobutanediol Polyester Films for Impact and Thermoformability

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Solution Overview

Problem

Current polyester films and sheets face challenges in achieving a combination of high impact strength, moderate glass transition temperature, chemical resistance, hydrolytic stability, and thermoformability while maintaining processability on standard industry equipment, as existing materials like polycarbonate suffer from poor melt processability and chemical resistance.

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 viscosity ranges, which allows for the production of films and sheets with improved properties without using polycarbonate, enabling easier processing and enhanced performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If polycarbonate is used to achieve high impact strength and heat resistance, then physical properties are improved, but melt processability deteriorates

Engineering Contradiction:

Improveimpact strengthVSAvoidmelt processability

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The invention changes the chemical composition parameters by replacing polycarbonate with a polyester containing 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 1,4-cyclohexanedimethanol in specific ratios (30-97 mol% and 3-70 mol% respectively), achieving a balance between impact strength and melt processability that polycarbonate cannot provide

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention creates a composite polyester material combining multiple diol components (2,2,4,4-tetramethyl-1,3-cyclobutanediol and 1,4-cyclohexanedimethanol) with dicarboxylic acids to achieve synergistic properties: the cyclobutanediol component provides impact strength while the cyclohexanedimethanol component ensures processability and chemical resistance

Inventive Principle:

Principle #40Composite materials

2Loss of time

If sufficient ethylene glycol is added to PCT to slow 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:

Loss of timeVSStrength

Solution Approach 1:

The invention changes the glycol composition parameters by replacing ethylene glycol with 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 1,4-cyclohexanedimethanol, achieving long crystallization half-times (≥5 seconds) while maintaining glass transition temperatures between -50°C and 50°C and high impact strengths (≥5 ft-lb/in), which ethylene glycol-modified PCT cannot achieve

Inventive Principle:

Principle #35Parameter changes

3Strength

If 2,2,4,4-tetramethyl-1,3-cyclobutanediol is used to improve impact strength, then toughness is improved, but inherent viscosity and glass transition temperature increase excessively

Engineering Contradiction:

Improveimpact strengthVSAvoidglass transition temperature

Core Design Contradiction:

StrengthVSTemperature

Solution Approach 1:

The invention optimizes the ratio parameters of 2,2,4,4-tetramethyl-1,3-cyclobutanediol (30-97 mol%) and 1,4-cyclohexanedimethanol (3-70 mol%) to control glass transition temperature between -50°C and 50°C, preventing excessive temperature increase while maintaining high impact strength and toughness

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention creates a composite diol system combining 2,2,4,4-tetrimethyl-1,3-cyclobutanediol (providing impact strength) with 1,4-cyclohexanedimethanol (modulating glass transition temperature), achieving synergistic effects that neither component can provide alone

Inventive Principle:

Principle #40Composite materials

4Productivity

If PCT is used to achieve rapid crystallization, then crystallization rate is improved, but ease of forming amorphous articles deteriorates

Engineering Contradiction:

Improvecrystallization rateVSAvoidease of forming amorphous articles

Core Design Contradiction:

ProductivityVSEase of manufacture

Solution Approach 1:

The invention changes the compositional parameters by incorporating 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 1,4-cyclohexanedimethanol in specific ratios, which slows crystallization rate (half-time ≥5 seconds) to enable formation of amorphous articles while maintaining other desirable properties

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentEP1913051B1Film(s) and/or sheet(s) comprising polyester compositions which comprise cyclobutanediol and have a certain combination of inherent viscosity and moderate glass transition temperature

Publication Date: 2010.02.24 EASTMAN CHEM CO

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AI summary

Described are film(s) and/or sheet(s) comprising polyesters comprising (a) a dicarboxylic acid component having terephthalic acid residues; optionally, aromatic dicarboxylic acid residues or aliphatic dicarboxylic residues; 2,2,4,4- tetramethyl-1 ,3-cyclobutanediol residues; and 1 ,4-cyclohexanedimethanol residues.