Regenerated Polyester Resin Coloration Reduction
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Solution Overview
Problem
Current methods for recycling polyethylene terephthalate (PET) containers result in regenerated polyesters with coloration and high acetaldehyde and cyclic trimer content, leading to degraded quality and increased costs, particularly in mechanical recycling.
Innovation Solution
A method involving the mixing of recycled PET with a polycarboxylic acid and a polyol, followed by depolymerization and esterification, and subsequent polycondensation in the presence of an aluminum catalyst, to produce a regenerated polyester resin with reduced coloration and lower production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If mechanical recycling is used to recycle polyester containers, then cost-effectiveness and environmental load are improved, but coloration and quality degradation occur
Solution Approach 1:
The invention changes the chemical parameters of the recycling process by introducing a polycarboxylic acid and polyol system with specific catalysts (antimony or germanium compounds) to control the depolymerization and repolymerization conditions, thereby reducing coloration while maintaining cost-effectiveness
Solution Approach 2:
The invention uses a polycarboxylic acid (such as terephthalic acid) and polyol (such as ethylene glycol) as intermediary substances to facilitate the chemical recycling process, enabling controlled decomposition and reformation of polyester chains with reduced coloration
2Object-affected harmful factors
If chemical recycling is used to decompose polyester to monomer level, then quality is improved, but energy consumption and process complexity increase
Solution Approach 1:
The invention segments the chemical recycling process into two distinct stages: first depolymerization to monomer level, then controlled repolymerization with specific catalysts. This segmentation allows optimization of each step to reduce overall energy consumption while maintaining quality
Solution Approach 2:
The invention changes the chemical parameters by using specific catalyst systems (antimony or germanium compounds in combination with polycarboxylic acid and polyol) to control the repolymerization step, enabling lower energy consumption while producing high-quality regenerated polyester with reduced coloration
3Ease of manufacture
If conventional polyester production catalysts are used in recycling, then production cost is reduced, but coloration and quality degradation occur
Solution Approach 1:
The invention uses inexpensive antimony or germanium catalyst compounds that can be easily added to the recycling process, providing effective catalysis for controlled repolymerization while maintaining low production costs and reducing coloration
Solution Approach 2:
The invention changes the catalyst parameters by using antimony or germanium compounds in specific concentrations (0.01-5 wt%) combined with polycarboxylic acid and polyol, optimizing the catalytic activity to reduce coloration while keeping production costs low
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 method effectively reduces coloration and production costs while maintaining the mechanical strength and impact resistance of the regenerated polyester resin, achieving improved quality and efficiency.
Implementation Method 1
the polycondensation in the second step is performed in the presence of an aluminum compound
Implementation Method 2
mixing a polyester resin (A) collected for recycling, a polycarboxylic acid (B), and a polyol (C) followed by depolymerizing and esterifying the polyester resin (A)
Data Source
AI summary
An object of the present invention is to provide a method for producing a regenerated polyester resin with reduced coloration at low cost. A method for producing a regenerated polyester resin, comprising: the first step of mixing a polyester resin (A) collected for recycling, a polycarboxylic acid (B), and a polyol (C) followed by depolymerizing and esterifying the polyester resin (A); and the second step of performing polycondensation of a reactant produced by the first step to form the regenerated polyester resin, wherein a content of the polyester resin (A) is from 5 parts by mass to 80 parts by mass with respect to 100 parts by mass of the regenerated polyester resin, the polycondensation in the second step is performed in the presence of an aluminum compound, and a content of the aluminum compound is from 5 ppm by mass to 100 ppm by mass on an aluminum element basis with respect to the reactant produced by the first step.