Continuous Polyester Melt Segmentation for Low Acetaldehyde
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Solution Overview
Problem
Current methods for producing polyester bottles involve costly and time-consuming steps like solid-state polycondensation and the use of expensive acetaldehyde scavengers to reduce acetaldehyde content, which can lead to increased production costs and potential contamination from scavenger residues.
Innovation Solution
A continuous process that divides the polyester melt into two partial streams, where one stream is directly fed into a shaping unit without acetaldehyde scavengers and the other undergoes dealdehydization to produce a low-acetaldehyde content layer, eliminating the need for costly scavengers and complex degassing steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If solid-state polycondensation and acetaldehyde scavengers are used to reduce acetaldehyde content, then acetaldehyde content is reduced, but production costs increase and scavenger residue contamination occurs
Solution Approach 1:
The polyester melt is divided into two separate partial streams: one stream is directly shaped without additional treatment, while the other stream undergoes dealdehydization treatment. This segmentation allows different processing paths for different layers, reducing the need for expensive scavengers in the final product while still achieving low acetaldehyde content in contact layers.
Solution Approach 2:
The dealdehydization treatment is performed on one partial stream before shaping, removing acetaldehyde in advance. This preliminary action eliminates the need for expensive scavengers during or after shaping, reducing production costs while ensuring low acetaldehyde content in the final product.
2Object-affected harmful factors
If acetaldehyde scavengers are used to reduce acetaldehyde content, then acetaldehyde content is reduced, but scavenger residue contamination occurs
Solution Approach 1:
By dividing the melt into two streams and applying dealdehydization to only one stream, the invention avoids introducing scavengers into the final product. The low-acetaldehyde layer is created through thermal treatment rather than chemical scavenging, eliminating scavenger residue contamination while maintaining low acetaldehyde content.
Solution Approach 2:
The invention converts the harmful effect of thermal history (which normally increases acetaldehyde) into a beneficial dealdehydization process. By carefully controlling thermal treatment of one partial stream, acetaldehyde is removed without requiring chemical scavengers, thus avoiding residue contamination.
3Object-affected harmful factors
If dealdehydization is performed on the entire polyester melt, then acetaldehyde content is reduced, but production time and complexity increase
Solution Approach 1:
Instead of treating the entire polyester melt with dealdehydization, the invention segments the melt into two streams and applies the time-consuming dealdehydization treatment to only one stream. This reduces overall production time while still achieving low acetaldehyde content in the final multi-layer molding through the combination of treated and untreated layers.
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 allows for the production of multi-layer moldings with low acetaldehyde content in contact layers, reducing production costs and preventing scavenger residue contamination, while maintaining mechanical properties and low acetaldehyde levels even after prolonged storage.
Implementation Method 1
The melt emerging from the final reactor is granulated
Implementation Method 2
the melt is degassed before being fed into the shaping device
Data Source
Figure 1(A)~1(L)
Figure 2
AI summary
The invention relates to a continuous method for the direct production of multilayer mold bodies from a highly condensed polyester melt.