Recycled DMT Polyester Processing in TPA-Based Reaction Zones
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Solution Overview
Problem
Existing methods for incorporating recycled dimethyl terephthalate (r-DMT) and recycled ethylene glycol (r-EG) into terephthalic acid-based (TPA-based) polyester manufacturing systems are not feasible without disrupting process settings and product uniformity, leading to increased costs and inefficiencies.
Innovation Solution
A method for manufacturing polyesters with recycle content by feeding a reaction zone with a recycle feed comprising r-DMT, transesterified r-DMT, and other recycle materials, and reacting the mixture under conditions typical for TPA-based processes, including temperatures above 250°C and residence times between 30 minutes and 12 hours, to form a polyester oligomer mixture, which is then polycondensed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If recycled monomers (r-DMT and r-EG) are incorporated into current TPA-based polyester manufacturing processes, then recycle content is achieved, but process settings are disrupted leading to non-uniform products and increased costs
Solution Approach 1:
The patent applies preliminary action by pre-converting recycled polyester into r-DMT and r-EG through depolymerization before incorporation into the TPA-based process. This preliminary conversion prepares the recycled materials in a form compatible with the existing manufacturing process, preventing disruptions and maintaining product uniformity while achieving recycle content
2Productivity
If current TPA-based manufacturing processes are used with recycled materials, then operational efficiency is maintained, but incorporation of recycle content becomes infeasible without manipulating process settings
Solution Approach 1:
The patent applies parameter changes by modifying the feed composition to include r-DMT and r-EG alongside TPA and glycols, while adjusting process parameters such as temperature, pressure, and catalyst conditions to accommodate the recycled materials. This enables incorporation of recycle content while maintaining operational efficiency through controlled parameter adjustments
3Quantity of substance
If additional process steps are implemented to incorporate recycled materials, then recycle content is achieved, but capital and manufacturing costs increase
Solution Approach 1:
The patent applies merging by integrating the depolymerization of recycled polyester and the TPA-based polyester manufacturing into a unified process flow. The r-DMT and r-EG from depolymerization are directly fed into the existing manufacturing process, eliminating the need for separate, costly processing steps and reducing overall manufacturing costs while achieving recycle content
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 allows for the efficient and cost-effective production of polyesters with recycled content, maintaining product uniformity and reducing the number of carboxyl ends and diethylene glycol content, while aligning with existing TPA-based manufacturing processes.
Implementation Method 1
In methanolysis, the polyester is reacted with methanol to produce a depolymerized polyester mixture comprising polyester oligomers, dimethyl terephthalate (DMT), and ethylene glycol (EG)
Implementation Method 2
reacting the reaction mixture to form a polyester oligomer mixture with recycled content
Implementation Method 3
The recycle feed may include dimethyl isophthalate recycle material and a residual catalyst material
Implementation Method 4
polycondensing the recycle content oligomer mixture to form a polyester with recycle content
Data Source
AI summary
A method for the manufacture of polyesters with recycle content by feeding to at least one reaction zone recycle feed comprising an ester recycle material selected from the group consisting of r-DMT, transesterified r-DMT and combinations thereof to form a reaction mixture comprising recycled content in at least one reaction zone; reacting the reaction mixture to form a polyester oligomer mixture with recycled content; and polycondensing the recycle content oligomer mixture to form a polyester with recycle content; wherein the feeding step further comprises feeding to at least one reaction zone a virgin feed, the virgin feed including at least one virgin diol component, the virgin feed further comprises a virgin diacid component, and the virgin diacid component is at least 90 mole % terephthalic acid based on the total diacid content of the virgin feed; and wherein the reacting step comprises reacting the reaction mixture at a temperature of at least 250° C. for a total average residence time of between 30 minutes and 12 hours.