Polyester Polymer Acetaldehyde Control via Catalyst Deactivation
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Solution Overview
Problem
There is a need for a polyester polymer that can achieve high intrinsic viscosity entirely in the melt phase without the solid-state polymerization step, while minimizing acetaldehyde (AA) generation, especially for water bottle applications which require very low AA levels, and also meet the IV requirements for carbonated soft drink bottles without using AA scavengers that add cost or affect the color of the polymer.
Innovation Solution
A polyester polymer composition comprising repeating alkylene arylate units and aluminum atoms, with a catalyst deactivator like phosphorus added late in the process to control catalytic activity, allowing for high IV build-up entirely in the melt phase and low AA levels, using a process where phosphorus is added to the polyester melt under specific conditions to deactivate catalysts and reduce AA generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If polyester is manufactured entirely in the melt phase to achieve high intrinsic viscosity, then productivity and manufacturing simplicity are improved, but acetaldehyde generation rate increases due to prolonged exposure to elevated temperatures
Solution Approach 1:
The patent applies preliminary action by adding a catalyst deactivator (phosphorus compound) during the melt phase polymerization process before the polyester is formed into particles. This deactivates the catalyst early in the process, preventing excessive acetaldehyde generation during subsequent melt processing, while still allowing high intrinsic viscosity to be achieved during the initial melt phase polymerization.
Solution Approach 2:
The patent changes the chemical parameter of catalyst activity by introducing a catalyst deactivator that modifies the catalytic environment. This allows the process to maintain high temperatures for melt phase polymerization (achieving high IV) while simultaneously reducing the catalyst's ability to generate acetaldehyde during later stages.
2Object-generated harmful factors
If AA scavengers are added to CSD resins to reduce acetaldehyde levels for water bottle applications, then acetaldehyde generation is reduced, but manufacturing cost increases and polymer color is affected
Solution Approach 1:
The patent extracts the need for separate AA scavenger addition by incorporating catalyst deactivation directly into the melt phase polymerization process itself. The phosphorus compound deactivator is integrated into the polyester synthesis, eliminating the need for post-synthesis AA scavenger addition and avoiding the associated costs and color issues.
Solution Approach 2:
The catalyst deactivator serves multiple functions: it controls acetaldehyde generation during melt processing, allows the use of active melt phase catalysts for high IV build-up, and eliminates the need for separate AA scavengers. This multi-functional approach simplifies the manufacturing process and reduces costs.
3Object-generated harmful factors
If solid-state polymerization is used to achieve high intrinsic viscosity, then acetaldehyde generation is reduced, but manufacturing complexity increases and additional process steps are required
Solution Approach 1:
The patent merges the advantages of melt phase processing (high IV build-up, simplified process) with the advantage of low AA generation by using a catalyst deactivator. This combines the high productivity of melt phase polymerization with the low AA generation benefit, eliminating the need for separate solid-state polymerization steps.
Solution Approach 2:
The patent changes the catalyst parameter during the melt phase process to achieve both high IV and low AA generation. By controlling catalyst activity through deactivation, the process achieves high intrinsic viscosity through melt phase polymerization while preventing excessive acetaldehyde generation, thus simplifying the overall process.
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 solution enables the production of polyester polymers with high intrinsic viscosity and low acetaldehyde levels without the need for AA scavengers, suitable for both water and carbonated soft drink bottle applications, reducing costs and maintaining polymer clarity.
Implementation Method 1
a polycondensation catalyst, which is effective to catalyze a polycondensation reaction to form polyester polymers having a desired intrinsic viscosity
Implementation Method 2
a catalyst deactivator effective to at least partially deactivate the catalytic activity of the combination of said (i) aluminum atoms and (ii) alkaline earth metal atoms or alkali metal atoms or alkali compound residues
Data Source
AI summary
A polyester polymer composition containing polyester polymers such as polymers having repeating ethylene terephthalate units, aluminum atoms in an amount of at least 3 ppm based on the weight of the polymer, the polyester polymers having an It.V. of at least 0.72 dL/g obtained through a melt phase polymerization and a residual acetaldehyde level of 10 ppm or less. Also provided are polyester polymer compositions containing polyester polymers and : (i) aluminum atoms (ii) alkaline earth metal atoms or alkali metal atoms or alkali compound residues, and (iii) a catalyst deactivator such as a phosphorus compound. The phosphorus compound is added to the polyester melt either late in the polycondensation or upon remelting a solid polyester polymer. The polyester polymer exhibits good L* brightness, clarity, and low levels of acetaldehyde generated upon melting.