Outdoor Sign Polyester Composition for Thermoforming Without Pre-Drying

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Solution Overview

Problem

Existing outdoor signs made from polycarbonates and polyesters face issues with blisters due to non-pre-dried films, rapid crystallization of poly(1,4-cyclohexylenedimethylene) terephthalate, and deficiencies in properties like glass transition temperature and impact strength, leading to difficulties in thermoformability and chemical resistance.

Innovation Solution

Development of polyester compositions comprising terephthalic acid, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, and 1,4-cyclohexanedimethanol with specific monomer ratios and inherent viscosities, allowing for improved impact strength, hydrolytic stability, chemical resistance, and thermoformability while maintaining processability on standard equipment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If polycarbonate is used for outdoor signs, then impact strength and clarity are improved, but pre-drying is required to prevent blisters and chemical resistance is poor

Engineering Contradiction:

Improveimpact strengthVSAvoidpre-drying requirement

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The patent changes the chemical composition parameters by using polyester compositions with specific monomer ratios (70-100% terephthalic acid, 1-99% 1,4-cyclohexanedimethanol, 1-99% 2,2,4,4-tetramethyl-1,3-cyclobutanediol) and controlled inherent viscosity (0.1-1.2 dL/g) to achieve both impact strength and elimination of pre-drying requirements

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite polyester material combining multiple monomers (terephthalic acid, 1,4-cyclohexanedimethanol, and 2,2,4,4-tetramethyl-1,3-cyclobutanediol) to achieve properties superior to single-component polycarbonate, including improved impact strength, chemical resistance, and processability

Inventive Principle:

Principle #40Composite materials

2Reliability

If poly(1,4-cyclohexylenedimethylene) terephthalate is used, then chemical resistance is improved, but crystallization rate is too rapid for easy forming

Engineering Contradiction:

Improvechemical resistanceVSAvoidcrystallization rate

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent modifies the crystallization parameters by incorporating 2,2,4,4-tetramethyl-1,3-cyclobutanediol which increases the crystallization half-time from seconds to minutes, allowing sufficient time for thermoforming while maintaining chemical resistance through the polyester structure

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces local structural modifications by incorporating cyclobutanediol units into the polyester chain, which locally disrupts rapid crystallization while preserving the overall chemical resistance properties of the polyester backbone

Inventive Principle:

Principle #3Local quality

3Loss of time

If ethylene glycol-modified PCT is used to slow crystallization, then crystallization half-time is improved, but glass transition temperature and impact strength decrease

Engineering Contradiction:

Improvecrystallization half-timeVSAvoidimpact strength

Core Design Contradiction:

Loss of timeVSStrength

Solution Approach 1:

The patent replaces ethylene glycol (which provides long crystallization half-times but poor mechanical properties) with 2,2,4,4-tetramethyl-1,3-cyclobutanediol that provides adequate crystallization control while maintaining superior impact strength and glass transition temperature

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent optimizes the monomer composition parameters to achieve a balance where crystallization half-time is extended to 10-60 minutes while maintaining glass transition temperature of 80-150°C and impact strength above 2 ft-lb/in, unlike ethylene glycol modifications that sacrifice mechanical properties

Inventive Principle:

Principle #35Parameter changes

4Strength

If 2,2,4,4-tetramethyl-1,3-cyclobutanediol polyester is used, then impact strength and Tg are improved, but inherent viscosity becomes too high for standard equipment

Engineering Contradiction:

Improveimpact strengthVSAvoidinherent viscosity

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The patent precisely controls the inherent viscosity parameter within the range of 0.1-1.2 dL/g by adjusting monomer ratios and polymerization conditions, making the material processable on standard equipment while maintaining high impact strength through the cyclobutanediol structure

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses partial incorporation of 2,2,4,4-tetramethyl-1,3-cyclobutanediol (1-99% of glycol component) rather than pure cyclobutanediol polyester, achieving sufficient impact strength improvement while keeping viscosity manageable for industrial processing

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS7812112B2Outdoor signs comprising polyester compositions formed from 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 1,4-cyclohexanedimethanol

Publication Date: 2010.10.12 EASTMAN CHEM CO

AI summary

Described are outdoor signs comprising polyester compositions comprising polyesters which comprise (a) a dicarboxylic acid component having terephthalic acid residues; optionally, aromatic dicarboxylic acid residues or aliphatic dicarboxylic acid residues or ester residues thereof; 2,2,4,4-tetramethyl-1,3-cyclobutanediol residues; and 1,4-cyclohexanedimethanol residues.