Cyclobutanediol Polyester Composition for Slow Crystallization Molding
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Solution Overview
Problem
Current polyester compositions, such as poly(1,4-cyclohexylenedimethylene terephthalate) and ethylene glycol-modified copolyesters, face challenges in achieving a balance of high impact strength, moderate glass transition temperature, toughness, chemical resistance, and processability, while also exhibiting rapid crystallization that complicates the formation of amorphous articles.
Innovation Solution
The development of polyester compositions incorporating terephthalic acid, 1,4-cyclohexanedimethanol, and 2,2,4,4-tetramethyl-1,3-cyclobutanediol, with specific monomer ratios and the use of thermal stabilizers, which allows for the production of polyesters with improved impact strength, heat resistance, and processability on standard equipment, while minimizing crystallization rates and maintaining low densities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If sufficient ethylene glycol is included in the formulation to provide long crystallization half-times, then amorphous products can be formed, but glass transition temperature decreases and impact strength deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters by introducing 2,2,4,4-tetramethyl-1,3-cyclobutanediol as a comonomer替代ethylene glycol. This compositional parameter change achieves long crystallization half-times (greater than 5 minutes at 170°C) while maintaining glass transition temperatures above 80°C and improving impact strength, resolving the trade-off between crystallization control 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 (10-25 mole% of the cyclobutanediol component). This composite approach synergistically combines the benefits of slow crystallization with maintained thermal and mechanical properties, overcoming the limitations of single-component modifications
2Stability of the object's composition
If PCT crystallizes rapidly upon cooling from the melt, then high crystallinity is achieved, but it becomes very difficult to form amorphous articles by extrusion or injection molding
Solution Approach 1:
The patent modifies the crystallization kinetics by incorporating 2,2,4,4-tetramethyl-1,3-cyclobutanediol, which increases the crystallization half-time to greater than 5 minutes at 170°C. This parameter change in crystallization rate enables sufficient processing time for extrusion and injection molding while still achieving controlled crystallinity in the final product
Solution Approach 2:
The patent performs preliminary modification of the polyester composition before processing by incorporating comonomers that retard crystallization. This preliminary action of slowing crystallization kinetics allows the material to remain processable during molding operations, enabling the formation of amorphous articles before crystallization occurs
3Strength
If 2,2,4,4-tetramethyl-1,3-cyclobutanediol is used to improve impact strength and reduce crystallization rate, then inherent viscosity increases, but standard equipment becomes insufficient for manufacturing
Solution Approach 1:
The patent optimizes the concentration parameter of 2,2,4,4-tetramethyl-1,3-cyclobutanediol to 10-25 mole% of the total diol content. This parameter optimization balances the competing effects: sufficient comonomer content to achieve long crystallization half-times and improved impact strength, while limiting inherent viscosity increase to levels that remain compatible with standard industry manufacturing equipment
Solution Approach 2:
The patent applies partial action by using a moderate amount of the cyclobutanediol comonomer (10-25 mole%) rather than high concentrations. This partial incorporation provides sufficient modification to achieve the desired crystallization control and mechanical property improvements without excessive viscosity increase that would require specialized equipment
Data Source
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AI summary
Described as one aspect of the invention are polyesters containing (a) a dicarboxylic acid component having from 70 to 100 mole % of terephthalic acid residues and up to 30 mole% of aromatic dicarboxylic acid residues or aliphatic dicarboxylic acid residues; and (b) a glycol component having from 11 to 25 mole % of 2,2,4 ,4-tetramethyl-1 ,3-cyclobutanediol residues, and 75 to 89 mole % of 1 ,4-cyclohexanedimethanol residues; wherein the total mole % of the dicarboxylic acid component is 100 mole %, and the total mole % of the glycol component is 100 mole %. The polyesters may be manufactured into articles.