TMCD Polyester Composition for Impact Strength and Thermoformability
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Solution Overview
Problem
Current polyester compositions face challenges in achieving a balance of high impact strength, toughness, hydrolytic stability, chemical resistance, and thermoformability while maintaining processability on standard industry equipment, with existing polymers either exhibiting undesirable properties such as high ductile-to-brittle transition temperatures or poor melt processability.
Innovation Solution
The development of polyester compositions comprising terephthalic acid, 1,4-cyclohexanedimethanol, and specific cis/trans ratios of 2,2,4,4-tetramethyl-1,3-cyclobutanediol, which offer a unique combination of properties including high impact strength, hydrolytic stability, chemical resistance, and thermoformability, while being processable on standard equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If sufficient ethylene glycol is included in the formulation to provide long crystallization half-times, then amorphous products can be obtained, but glass transition temperature and impact strength deteriorate
Solution Approach 1:
The patent changes the chemical composition parameters by replacing ethylene glycol with 2,2,4,4-tetramethyl-1,3-cyclobutanediol (TMCD). This substitution fundamentally alters the polymer structure, achieving long crystallization half-times through the cyclic diol's steric hindrance and molecular structure, while simultaneously maintaining high impact strength and glass transition temperature that ethylene glycol modifications cannot achieve
Solution Approach 2:
The patent creates a composite polyester system combining terephthalic acid, 1,4-cyclohexanedimethanol, and 2,2,4,4-tetramethyl-1,3-cyclobutanediol. This multi-component composition synergistically achieves amorphous product formation with long crystallization half-times while maintaining superior mechanical properties including high impact strength and toughness, which neither ethylene glycol nor isophthalic acid modifications can achieve alone
2Strength
If 2,2,4,4-tetramethyl-1,3-cyclobutanediol is used to improve impact strength and toughness, then glass transition temperature increases, but inherent viscosity and melt viscosity increase making processing difficult
Solution Approach 1:
The patent optimizes the TMCD content parameter within specific ranges (1-99 mol%, preferably 20-80 mol%) to balance the conflicting properties. By controlling the concentration of TMCD units in the polymer chain, the invention achieves high impact strength and glass transition temperature while limiting excessive viscosity increase that would compromise melt processability on standard equipment
Solution Approach 2:
The patent introduces local structural variation through the cyclic diol units within the polyester chain. The 2,2,4,4-tetramethyl-1,3-cyclobutanediol units create localized rigid segments that enhance impact strength and Tg, while the overall polymer architecture and other flexible segments maintain sufficient chain mobility for processing, achieving local property optimization without global property deterioration
3Strength
If PCT crystallizes rapidly upon cooling from the melt, then high strength and rigidity are achieved, but it becomes very difficult to form amorphous articles by extrusion or injection molding
Solution Approach 1:
The patent introduces 2,2,4,4-tetramethyl-1,3-cyclobutanediol as an intermediary component that modifies the crystallization behavior of the polyester system. This cyclic diol acts as a crystallization inhibitor, slowing down the crystallization rate and extending the processing window, thereby enabling the formation of amorphous articles through extrusion and injection molding while maintaining the strength and rigidity characteristics of PCT
Data Source
AI summary
Described are polyester compositions comprising (a) a dicarboxylic acid component comprising 80 to 100 mole % terephthalic acid residues; optionally, aromatic dicarboxylic acid or aliphatic dicarboxylic acid residues; 30 to 40 mole % of 2,2,4,4-tetramethyl-1,3-cyclobutanediol residues, where said 2,2,4,4-tetramethyl-1,3-cyclobutanediol residues comprise at least 55 mole % cis-2,2,4,4-tetramethyl-1,3-cyclobutanediol; and 60 to 70 mole % 1,4-cyclohexanedimethanol residues.