Compartmentalized Resin Pellets for Polyester Acetaldehyde Control
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Solution Overview
Problem
The use of titanium catalysts in polyester resin production for bottle-grade polyesters is limited due to the catalytic formation of acetaldehyde, which is exacerbated when combined with phosphorus compounds, as the phosphorus deactivates the titanium catalyst, making it difficult to achieve the desired catalytic effect and low acetaldehyde levels simultaneously.
Innovation Solution
A compartmentalized resin pellet with a major polyester containing a catalytic titanium compound in one zone and a minor polyester with a phosphorus compound in another zone, allowing the titanium catalyst to remain active during polymerization and be deactivated only during extrusion, thereby controlling acetaldehyde levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If phosphorus compounds are added to polyester during melt phase polymerization to reduce acetaldehyde, then acetaldehyde levels are reduced, but the titanium catalyst is deactivated leading to longer polymerization times
Solution Approach 1:
The resin pellet is divided into two distinct zones: a first zone containing titanium catalyst and a second zone containing phosphorus compound. This spatial segmentation prevents the phosphorus from deactivating the titanium catalyst during polymerization, while still allowing both components to be present in the final product to control acetaldehyde formation.
Solution Approach 2:
The compartmentalized pellet structure acts as an intermediary mechanism that separates the titanium catalyst and phosphorus compound until the appropriate stage. The physical barrier of the pellet structure prevents premature interaction, allowing the titanium to catalyze polymerization efficiently while the phosphorus remains isolated until needed for acetaldehyde control.
2Productivity
If titanium catalysts are used to accelerate polymerization, then polymerization time is reduced, but acetaldehyde formation increases
Solution Approach 1:
By segmenting the pellet into separate zones for titanium and phosphorus, the invention allows the titanium catalyst to operate at full efficiency during polymerization without being deactivated by phosphorus. The phosphorus compound is isolated in a separate zone, preventing harmful interaction while still being available to control acetaldehyde formation in the final product.
3Reliability
If phosphorus compounds are added during melt phase polymerization to stabilize polyester, then polyester stability is improved, but titanium catalyst activity is reduced
Solution Approach 1:
The pellet is segmented into distinct functional zones: the first zone contains the titanium catalyst for driving polymerization, while the second zone contains the phosphorus compound for stabilizing the polyester and controlling acetaldehyde. This segmentation ensures that the phosphorus does not interfere with titanium catalyst activity during the polymerization process.
Solution Approach 2:
The phosphorus compound is pre-positioned in the second zone of the pellet, ready to perform its stabilizing function after polymerization. The compartmentalized structure ensures the phosphorus is in place before the polymerization process begins, but isolated from the titanium catalyst until the appropriate stage.
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 approach enables the full catalytic effect of titanium during polymerization while maintaining low acetaldehyde levels in the injection-molded preform, reducing polymerization time and acetaldehyde formation, unlike previous methods where phosphorus deactivation of titanium catalysts resulted in longer polymerization times and higher acetaldehyde levels.
Implementation Method 1
a major polyester comprising a catalytic titanium compound
Implementation Method 2
the phosphorus compound deactivates the titanium polycondensation catalyst during the melt phase polymerization
Implementation Method 3
They are used to produce exceptionally good colorless clear containers, such as those required for bottled water. However, the significant catalytic effect of titanium also catalyzes the production of acetaldehyde when the polyester resin is extruded and injection molded into the preform.
Implementation Method 4
They are used to stabilize the polymer and prevent the formation of acetaldehyde
Data Source
AI summary
Disclosed herein is a resin pellet and a process to make said resin pellet. The resin pellet comprises a major polyester comprising a catalytic titanium compound, and a minor polyester comprising a phosphorus compound. The major polyester is present in a first compartmentalized zone of the resin pellet and the minor polyester is present in a second compartmentalized zone of the resin pellet.