Titanium-Antimony Catalyst for Crystallizable Polyester Color Control
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Solution Overview
Problem
The production of crystallizable polyester compositions containing neopentyl glycol (NPG) requires extreme reaction conditions and specialized catalysts, leading to issues such as high yellow color and reduced polymerization rates, and poses challenges in recycling due to incompatibility with PET streams.
Innovation Solution
A catalyst system comprising a low level of titanium combined with antimony and phosphorus is used to produce polyester compositions with improved color and reaction rates, allowing for crystallizable polyesters that are recyclable and compatible with PET streams, maintaining performance properties like high strain-induced crystalline melting points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a titanium-only catalyst system is used to produce crystallizable polyester compositions containing NPG, then the polyester can be produced, but the product exhibits very high yellow color (high b* values)
Solution Approach 1:
The patent changes the catalyst system parameters by introducing antimony compounds (e.g., antimony trioxide, antimony acetate) in combination with titanium compounds. This parameter change resolves the contradiction by achieving both acceptable color (reduced b* values) and maintained polymerization rates, as the antimony-titanium combination provides synergistic catalytic activity while reducing yellowing compared to titanium-only systems.
Solution Approach 2:
The patent employs a composite catalyst system combining titanium and antimony compounds. This composite approach allows the system to leverage the high catalytic activity of titanium for polymerization rate while the antimony component moderates the yellow color formation, achieving both desired productivity and color quality simultaneously.
2Object-affected harmful factors
If phosphorus loading is increased to reduce yellow color, then color improves, but polymerization rate decreases
Solution Approach 1:
The patent changes the catalyst composition parameters by introducing antimony compounds that interact with phosphorus compounds to create a more balanced system. This allows for reduced phosphorus loading while maintaining both color quality and polymerization rate, as the antimony-titanium-phosphorus combination provides synergistic effects that prevent yellowing without sacrificing productivity.
3Object-affected harmful factors
If titanium level is decreased to improve color, then color improves slightly, but polymerization rate is reduced
Solution Approach 1:
The patent optimizes the titanium level in combination with antimony and phosphorus compounds. This parameter optimization allows for lower titanium loading (improving color) while the antimony-phosphorus combination compensates for the reduced titanium activity, maintaining adequate polymerization rates through synergistic catalytic effects.
4Manufacturing precision
If extreme reaction conditions are used to incorporate NPG, then desired molecular weight is achieved, but glycol degradation increases and product color deteriorates
Solution Approach 1:
The patent changes the reaction parameters by using a titanium-antimony-phosphorus catalyst system that enables NPG incorporation at more moderate conditions. This catalyst combination provides high activity and selectivity, allowing achieving desired molecular weight without the extreme conditions that cause glycol degradation and color deterioration.
Solution Approach 2:
The patent uses small amounts of phosphorus compounds as catalyst moderators that are consumed during the reaction to control color and degradation. These short-living additives protect the main polymer structure by sacrificing themselves to moderate the reaction and prevent harmful side reactions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The titanium-antimony catalyst system produces polyesters with better color and equivalent reaction rates compared to titanium-only systems, ensuring compatibility and recyclability without impacting PET recycling processes, and maintains high strain-induced crystalline melting points for performance in applications like heat-shrinkable films.
Implementation Method 1
a catalyst system comprising a low level of titanium combined with antimony and phosphorus is used to produce polyester compositions with improved color and reaction rates
Data Source
AI summary
The present disclosure relates to a catalyst system to produce crystallizable polyester compositions which comprise residues of terephthalic acid, neopentyl glycol (NRG), 1,4-cyclohexanedimethanol (CHDM), ethylene glycol (EG), and diethylene glycol (DEG), in certain compositional ranges having certain advantages and improved properties including recyclability.