TMCD Polyester Films With Slow Crystallization and High Impact Strength
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Solution Overview
Problem
Current polyester films and sheets based on terephthalic acid and 1,4-cyclohexanedimethanol exhibit deficiencies in properties such as glass transition temperature and impact strength due to rapid crystallization, and existing alternatives like polycarbonate have poor chemical resistance and processability issues.
Innovation Solution
Development of polyester compositions comprising terephthalic acid, 1,4-cyclohexanedimethanol, and 2,2,4,4-tetramethyl-1,3-cyclobutanediol with specific inherent viscosities and glass transition temperatures, which allow for high impact strength, hydrolytic stability, and thermoformability without the need for polycarbonate, using minimal ethylene glycol and potentially incorporating thermal stabilizers or branching agents.
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) in the polyester formulation. This substitution fundamentally alters the polymer structure to achieve long crystallization half-times while maintaining high impact strength and appropriate glass transition temperature, resolving the trade-off between crystallization rate and mechanical properties.
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 in specific ratios. This composite approach allows the material to exhibit both slow crystallization (long half-time) and high impact strength simultaneously, overcoming the limitations of single-component systems.
2Strength
If 2,2,4,4-tetramethyl-1,3-cyclobutanediol is used to achieve high glass transition temperature and impact strength, then inherent viscosity and melt viscosity increase excessively, but processability deteriorates
Solution Approach 1:
The patent optimizes the concentration parameter of 2,2,4,4-tetramethyl-1,3-cyclobutanediol within a specific range (5-50 mole%) rather than using it in excess. This controlled parameter adjustment maintains high impact strength and glass transition temperature while preventing excessive viscosity buildup that would compromise processability on standard equipment.
Solution Approach 2:
The patent introduces ethylene glycol as a local modifying component (0.1-15 mole%) within the polyester structure. This localized inclusion serves to reduce overall melt viscosity and improve processability without significantly compromising the impact strength and thermal properties provided by the TMCD component.
3Temperature
If polycarbonate is used as an alternative to achieve high heat resistance and impact strength, then chemical resistance and melt processability deteriorate
Solution Approach 1:
The patent replaces expensive polycarbonate with a polyester composition based on more readily available and cost-effective components (terephthalic acid, cyclohexanedimethanol, and TMCD). This substitution achieves comparable heat resistance and impact strength while providing superior chemical resistance and better processability on standard equipment, offering a more economical and performant solution.
Data Source
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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 or aliphatic dicarboxylic acid residues; 2,2,4,4- tetramethyl-1,3-cyclobutanediol residues; and 1,4-cyclohexanedimethanol residues.