Recycled PBT Recovery by Solvent Dissolution and Precipitation
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Solution Overview
Problem
Existing methods for recycling polybutylene terephthalate (PBT) composite materials face challenges in removing impurities and additives, leading to decreased mechanical strength and molecular weight, and chemical recycling methods incur high environmental costs and energy consumption.
Innovation Solution
A method involving dissolving PBT in a phenolic solvent to separate and precipitate PBT, using filtration and specific solvents to remove impurities, followed by drying, without chemical decomposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If material recycling is performed on PBT composite materials containing fillers and additives, then recycling can be attempted, but impurities cannot be removed and mechanical strength decreases due to filler cracking
Solution Approach 1:
The patent extracts and removes fillers and additives from the PBT composite material through a multi-step process involving solvent dissolution, filtration, and precipitation. The PBT is dissolved in a phenolic solvent, filtered to remove insoluble fillers and additives, then precipitated to obtain pure recycled PBT, thereby separating the desired polymer from harmful impurities that would otherwise degrade mechanical strength
Solution Approach 2:
The patent changes the physical and chemical parameters of the PBT composite material by controlling temperature, solvent composition, and precipitation conditions. By optimizing these parameters, the process achieves complete dissolution of PBT while leaving fillers and additives undissolved, enabling effective separation and recovery of high-purity recycled PBT with restored mechanical properties
2Productivity
If chemical recycling is used to decompose PBT into monomers, then PBT can be recovered, but the process requires large amounts of heat energy and creates high environmental load
Solution Approach 1:
The patent replaces the chemical decomposition mechanism (chemical recycling) with a physical separation mechanism using solvent dissolution and precipitation. Instead of breaking down PBT into monomers through chemical reactions requiring high heat energy, the process uses phenolic solvents to dissolve PBT at moderate temperatures, then precipitates it by adding non-solvents, thereby recovering PBT with minimal energy input and no chemical degradation
Solution Approach 2:
The patent utilizes changes in solubility parameters of PBT in phenolic solvents at different temperatures and compositions. By controlling temperature (heating to dissolve, then cooling to precipitate) and solvent ratios, the process achieves efficient PBT recovery without the high energy costs of chemical depolymerization and repolymerization
3Productivity
If repeated material recycling is performed on PBT, then recycling volume increases, but molecular weight decreases and mechanical strength deteriorates
Solution Approach 1:
The patent extracts and removes degradation byproducts, oxidized fragments, and other impurities that accumulate during repeated recycling through the solvent dissolution-filtration-precipitation process. Each recycling cycle uses fresh phenolic solvent to dissolve PBT, filtering out any degraded components that did not dissolve, thereby preventing molecular weight reduction and maintaining compositional stability across multiple recycling iterations
Solution Approach 2:
The patent maintains molecular weight stability by controlling the dissolution and precipitation parameters. By using phenolic solvents at optimized temperatures and concentrations, the process ensures complete dissolution of PBT without causing chain scission, and controlled precipitation that preserves polymer chain integrity, thereby maintaining consistent molecular weight and mechanical properties through repeated recycling
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 method enables the production of high-quality recycled PBT with minimal environmental impact and process complexity, maintaining mechanical properties.
Implementation Method 1
a step of dissolving a polybutylene terephthalate composite material in a solvent (S) containing a phenolic solvent to obtain a solution containing polybutylene terephthalate dissolved therein
Implementation Method 2
a step of removing an insoluble matter from the solution containing polybutylene terephthalate dissolved therein to obtain a liquid component (L) containing polybutylene terephthalate dissolved therein
Implementation Method 3
a step of mixing the liquid component (L) and a solvent (P) capable of precipitating polybutylene terephthalate by being mixed with the liquid component (L) to precipitate polybutylene terephthalate
Implementation Method 4
separating the slurry into solid and liquid to obtain a solid polybutylene terephthalate
Implementation Method 5
a step of drying the solid polybutylene terephthalate to obtain a recycled polybutylene terephthalate
Data Source
AI summary
Provided is a method for producing a recycled polybutylene terephthalate (PBT) with practically acceptable quality and low environmental load. A method for producing a recycled PBT including a step (A) of dissolving a PBT composite material in a solvent (S) containing a phenolic solvent to obtain a solution containing PBT dissolved therein, a step (B) of removing an insoluble matter from the solution containing PBT dissolved therein to obtain a liquid component (L) containing PBT dissolved therein, a step (C) of mixing the liquid component (L) and a solvent (P) capable of precipitating PBT by being mixed with the liquid component (L) to precipitate PBT, thereby obtaining a slurry, and then separating the slurry into solid and liquid to obtain a solid PBT, and a step (D) of drying the solid PBT to obtain a recycled PBT.