Oligomeric PET Substrate for Higher-Yield Recycled PET
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Solution Overview
Problem
Existing rPET manufacturing processes using rBHET derived from post-consumer PET waste exhibit lower reactivity and yield approximately 20% less rPET compared to vPET processes, and rPET tends to be darker and more yellow due to impurities, making them less competitive.
Innovation Solution
A method involving combined hydrolysis and glycolysis of post-consumer PET-containing waste material with ethylene glycol and water to produce an oligomeric PET substrate represented by Formula I, which has an optimized carboxyl end group to hydroxyl end group ratio and increased reactivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If rBHET is used in PET manufacturing process, then recycled PET can be produced from post-consumer PET waste, but the reactivity is lower and yield is approximately 20% less compared to vPET processes
Solution Approach 1:
The patent modifies the chemical parameters of the oligomer by controlling the degree of polymerization (n=1-10) and the ratio of carboxyl to hydroxyl end groups through optimized hydrolysis and glycolysis conditions. This creates an oligomeric PET substrate with enhanced reactivity and improved yield compared to conventional rBHET processes
Solution Approach 2:
The patent performs preliminary hydrolysis and glycolysis treatments on post-consumer PET waste to convert it into an optimized oligomeric PET substrate before subsequent polymerization. This preliminary chemical transformation prepares the material with improved reactive end groups, solving the reactivity issue before the main polymerization step
2Ease of manufacture
If conventional glycolysis is used to convert PET waste to rBHET, then recycling is achieved, but the product is darker and more yellow due to impurities
Solution Approach 1:
The patent converts the harmful effect of impurities that cause discoloration into a beneficial selective process. By using controlled hydrolysis and glycolysis with specific conditions (temperature, catalyst, stoichiometry), the process selectively breaks down PET chains while minimizing formation of colored impurities, actually improving the color quality of the recycled product
Solution Approach 2:
The patent changes the chemical parameters of the recycling process by using optimized hydrolysis and glycolysis conditions rather than conventional glycolysis alone. This includes controlling temperature, pressure, catalyst type and amount, and stoichiometric ratios to produce an oligomer with better color stability and fewer impurities
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 oligomeric PET substrate enhances the reactivity and polymerization ability of rPET, allowing it to compete with vPET processes, with improved yield and reduced color impurities.
Implementation Method 1
the oligomer upon which it is based is derived from post-consumer PET or PCR, rather than PTA... the BHET monomer polymerizes with itself to form longer chains of PET
Implementation Method 2
Reacting post-consumer PET-containing waste material in the presence of ethylene glycol and water in a reaction zone... combined hydrolysis and glycolysis of post-consumer PET-containing waste material
Implementation Method 3
This PCR flake may be glycolysed to convert it to rBHET... combined hydrolysis and glycolysis of post-consumer PET-containing waste material with ethylene glycol and water
Data Source
AI summary
Provided herein is a method for producing an oligomeric PET substrate from post-consumer PET-containing waste material, wherein said oligomeric PET substrate is for use in a rPET manufacturing process. The method comprises the steps of: i) Reacting post-consumer PET-containing waste material in the presence of ethylene glycol and water in a reaction zone; and ii) producing an oligomeric PET substrate represented by Formula I. Provided also is an oligomeric PET substrate from post-consumer PET-containing waste material, wherein said oligomeric PET substrate is represented by Formula I and also a PET polymer made from 5-100% rPET, which comprises the oligomeric PET substrate.