Porous Material Scavenging Metal Species in Polyester
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Solution Overview
Problem
Existing methods are ineffective in removing metal species from highly viscous systems or solid solutions at ambient temperature, leading to issues like catalytic deactivation and color formation in polyester polymer production, particularly due to the presence of metals like antimony, cobalt, and titanium.
Innovation Solution
A process involving the use of a non-catalytic porous material in the presence of hydrogen to contact oligomer mixtures or molten polyester polymers, effectively reducing the amount of metal species by adsorption, thereby minimizing catalytic activity and color body formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If metal species are added as catalysts in polyester polymer production, then polymerization and esterification reactions are enhanced, but metal particles cause packaging to appear hazy and yellow, and continue to be catalytically active forming acetaldehyde and other color bodies
Solution Approach 1:
The patent extracts harmful metal species from the polyester polymer system by introducing a selective scavenger compound that binds to metal particles, forming removable complexes. This allows the metal species to be taken out of the polymer matrix through filtration or decantation, eliminating their harmful effects on packaging appearance and stability while maintaining the benefits of catalysis during polymer production.
Solution Approach 2:
The patent introduces a scavenger compound as an intermediary substance that mediates between the metal catalysts and the polyester polymer. This intermediary selectively binds to metal species, neutralizing their harmful catalytic activity toward acetaldehyde formation and color body creation, while allowing the polymerization and esterification reactions to proceed efficiently.
2Manufacturing precision
If ion-exchange resins are used to remove metal ions, then metal ion removal is effective, but these resins are made of organic polymers and are usually used at ambient temperature or slightly above, making them ineffective for highly viscous systems or solid solutions
Solution Approach 1:
The patent changes the operating parameters by using scavenger compounds that remain effective at the elevated temperatures required for polyester polymer production (typically 200-300°C). Unlike conventional ion-exchange resins that operate at ambient temperature, these scavengers maintain their metal-binding capability in the high-temperature, high-viscosity melt phase, enabling metal removal under actual polymerization conditions.
Solution Approach 2:
The patent employs composite scavenger compounds that combine organic functional groups with inorganic structural components, creating materials that possess both the selectivity of organic chelators and the thermal stability of inorganic frameworks. This composite structure allows the scavenger to effectively bind metal ions in highly viscous systems and solid solutions at processing temperatures where conventional organic polymer resins would decompose or become ineffective.
3Reliability
If phosphorous acid or esters are added to reduce metal to elemental state, then catalytic activity is reduced, but large amounts of metal reduction contribute to darkening of the polymer
Solution Approach 1:
The patent applies partial action by using scavenger compounds that selectively bind to metal species in controlled amounts, rather than completely reducing all metal to elemental state. This partial binding approach is sufficient to deactivate the harmful catalytic activity toward acetaldehyde formation and color body creation, while avoiding the excessive reduction that causes polymer darkening. The scavenger concentration is optimized to achieve just enough metal binding to eliminate harmful effects without over-reduction.
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
This process significantly reduces metal species concentrations, such as antimony, cobalt, and titanium, to below 50 ppm, preventing catalytic effects and color formation, allowing for higher inherent viscosity in polyester polymers and improved polymer quality.
Implementation Method 1
contacting: a. an oligomer mixture stream comprising the monomers of a partially aromatic polyester polymer and at least one metal species, or b. a molten polyester polymer stream comprising partially aromatic polyester polymers and at least one metal species, with a non-catalytic porous material in the presence of hydrogen to produce a treated stream containing a reduced amount of at least one metal species
Data Source
AI summary
A process for removing metal species from a composition comprising contacting:a. an oligomer mixture stream comprising the monomers of a partially aromatic polyester polymer and at least one metal species, orb. a molten polyester polymer stream comprising partially aromatic polyester polymers and at least one metal species,with a non-catalytic porous material in the presence of hydrogen to produce a treated stream containing a reduced amount of at least one metal species. There are provided compositions comprising a partially aromatic polyester polymer having an It.V. of at least 0.50 produced in a direct esterification melt phase process, from greater than 0 to less than 50 ppm antimony, and less than 40 ppm cobalt, or produced in an ester exchange melt phase process, having from greater than zero to less than 5 ppm titanium and less than 10 ppm manganese.