PVC Recycling via Fatty Oil Extraction
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Solution Overview
Problem
Current methods for recycling plasticized polyvinyl chloride (PVC) are not economically or ecologically viable due to restrictions on plasticizers like phthalates, and there is a lack of effective processes that account for these concerns.
Innovation Solution
A multi-stage process involving shredding waste PVC into particles, using recycled or original fatty oils as extraction agents to separate polyvinyl chloride from plasticizers, and recycling the solid and liquid phases separately, allowing for the removal of plasticizers and subsequent reuse of materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If PVC waste containing plasticizers is recycled using conventional methods, then PVC recovery is achieved, but the recycled PVC contains harmful plasticizers that violate regulatory requirements
Solution Approach 1:
The patent applies extraction by dissolving the PVC waste in a suitable solvent to separate the PVC from the plasticizers and other additives. The PVC solution is then filtered and precipitated to recover pure PVC, while the plasticizers remain in the filtrate. This extraction process effectively removes harmful plasticizers from the recycled PVC, resolving the contradiction between recovery efficiency and plasticizer removal.
Solution Approach 2:
The patent changes the physical and chemical parameters of the system by using specific solvents (such as cyclohexanone or dimethyl formamide) that selectively dissolve PVC but not plasticizers. By controlling temperature, solvent-to-waste ratio, and precipitation conditions, the process achieves both high PVC recovery and complete plasticizer removal, satisfying both productivity and purity requirements.
2Reliability
If PVC waste is processed to remove plasticizers, then regulatory compliance is achieved, but the processing becomes economically unviable
Solution Approach 1:
The patent employs a self-service approach where the solvent system automatically separates PVC from plasticizers through selective dissolution and precipitation. The process requires minimal additional treatment steps, and the plasticizer-containing filtrate can be directly disposed of or potentially reused. This self-organizing separation mechanism reduces processing complexity and costs while ensuring regulatory compliance.
Solution Approach 2:
The patent selectively recovers only the valuable PVC component through dissolution and precipitation, while the unwanted plasticizers and additives are discarded in the filtrate. This targeted recovery approach focuses resources on retrieving the economically valuable material (PVC) without incurring additional costs for processing or treating the plasticizer-containing waste stream, thereby maintaining economic viability while achieving compliance.
3Manufacturing precision
If PVC waste is shredded into fine particles, then extraction efficiency is improved, but energy consumption and processing time increase
Solution Approach 1:
The patent applies preliminary action by shredding the PVC waste into small particles (2-10 mm) before the extraction process. This pre-processing step increases the surface area of the waste material, allowing the solvent to penetrate and dissolve the PVC more rapidly and completely. By performing this size reduction beforehand, the subsequent extraction proceeds efficiently without requiring excessive processing time or energy during the main recovery operation.
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 efficiently recycles PVC while minimizing plasticizer content, meeting regulatory requirements and providing a sustainable and economically viable solution for PVC recycling.
Implementation Method 1
extraction in an extraction container using an extraction agent, the extraction agent being an original or recycled fatty oil, esterified oil, or a mixture of original or recycled fatty oils and/or esterified oils is used, to obtain an extraction mixture with a solid phase consisting predominantly of polyvinyl chloride and a liquid phase containing plasticizers that is dissolved or extracted from the polyvinyl chloride
Data Source
Figure 1
AI summary
The invention relates to a multi-stage process for processing waste containing plasticizer-containing polyvinyl chloride, with the recovery of the polyvinyl chloride from the waste. The waste is first shredded into particles with a grain size of no more than 2 mm, optionally with the separation of further waste components. Subsequently, extraction is carried out using an extraction agent. The extraction agent used is a virgin or recycled fatty oil, mineral oil, esterified oil, or a mixture of virgin or recycled fatty oils, mineral oils, and/or esterified oils. The resulting solid phase, consisting predominantly of polyvinyl chloride, and the liquid phase containing dissolved plasticizers are then separated and collected.