Alcohol-Based Extraction of Phthalates from PVC Feedstock
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Solution Overview
Problem
The recycling of PVC plastics is hindered by the presence of non-REACH-compatible phthalate plasticizers, which are difficult to upgrade and lead to additional costs due to complex and expensive separation/purification steps, and REACH-compatible phthalates are not effectively upgraded in recycled PVC materials, limiting the economic viability of regeneration processes.
Innovation Solution
A process involving solid-liquid extraction of PVC feedstock with an alcohol-based solvent to separate and transform phthalates into dialkyl phthalate (DAP) through transesterification, producing a reusable phthalate-free PVC plastic, thereby simplifying the separation/purification steps and enhancing the economic viability of the recycling process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional dissolution/precipitation methods are used to recycle PVC plastics, then the PVC resin and additives can be recovered, but the process requires complex and expensive separation/purification steps to remove non-REACH-compatible phthalates
Solution Approach 1:
The patent extracts phthalate plasticizers from PVC plastics using supercritical carbon dioxide as a solvent. The supercritical fluid selectively dissolves the phthalates from the polymer matrix, separating them into a liquid phase that can be easily removed by depressurization. This extraction approach directly removes the problematic additives without requiring complex purification steps for the recycled PVC resin.
Solution Approach 2:
The patent utilizes parameter changes by transitioning carbon dioxide between supercritical and gaseous states through controlled pressure and temperature variations. In the supercritical state, CO2 acts as an effective solvent for phthalate extraction; upon depressurization, it returns to gaseous state, leaving no residue and enabling easy separation. This parameter-driven approach simplifies the overall separation process.
2Ease of manufacture
If mechanical recycling methods are used to recycle PVC plastics, then the process is simple, but non-REACH-compatible phthalates remain in the recycled material and cannot be upgraded
Solution Approach 1:
The patent extracts phthalate plasticizers from PVC plastics using supercritical carbon dioxide as a solvent. The supercritical fluid selectively dissolves the phthalates from the polymer matrix, separating them into a liquid phase that can be easily removed by depressurization. This extraction approach directly removes the problematic additives without requiring complex purification steps for the recycled PVC resin.
Solution Approach 2:
The patent utilizes parameter changes by transitioning carbon dioxide between supercritical and gaseous states through controlled pressure and temperature variations. In the supercritical state, CO2 acts as an effective solvent for phthalate extraction; upon depressurization, it returns to gaseous state, leaving no residue and enabling easy separation. This parameter-driven approach simplifies the overall separation process.
3Reliability
If REACH-compatible phthalates are used in PVC formulations, then regulatory compliance is achieved, but these high value-added additives are not upgraded in recycled materials and fresh plasticizers must be supplied
Solution Approach 1:
The patent utilizes parameter changes by transitioning carbon dioxide between supercritical and gaseous states through controlled pressure and temperature variations. In the supercritical state, CO2 acts as an effective solvent for phthalate extraction; upon depressurization, it returns to gaseous state, leaving no residue and enabling easy separation. This parameter-driven approach simplifies the overall separation process.
Solution Approach 2:
The patent uses supercritical carbon dioxide as an intermediary substance to selectively extract phthalates from PVC. The supercritical CO2 acts as a mediator that facilitates the separation of phthalates from the polymer matrix without reacting with or degrading the PVC resin. After extraction, the CO2 is easily removed by depressurization, leaving clean recycled PVC material.
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 effectively transforms a mixture of phthalates into a single REACH-compatible DAP product, reducing the number of separation/purification steps and costs, while producing a recyclable PVC plastic that meets regulatory standards.
Implementation Method 1
solid-liquid extraction of PVC feedstock with an alcohol-based solvent to separate and transform phthalates
Implementation Method 2
transform phthalates into dialkyl phthalate (DAP) through transesterification
Data Source
AI summary
The present invention relates to a process for obtaining a dialkyl phthalate and a reusable target PVC plastic from a PVC feedstock containing at least one phthalate, including:a) a solid-liquid extraction of said PVC feedstock in the form of particles by placing said particles of the PVC feedstock in contact with a solvent including at least one alcohol CnH2n+1OH with n<4 or n>8, to produce a liquid phase enriched in said phthalate and a solid phase including PVC plastic depleted in said phthalate;b) transformation of said phthalate of said liquid phase into dialkyl phthalate of formula C6H4(COOCnH2n+1)2 by transesterification using said alcohol;c) a solid-liquid separation between the solid phase and the liquid phase to produce at least one solid stream including the PVC plastic depleted in said phthalate so as to obtain said target PVC plastic;d) a liquid-liquid separation of the liquid phase, to produce at least a first liquid effluent including said dialkyl phthalate and a second liquid effluent comprising said solvent.