Available Technologies

Background

In recycling of waste plastics, demand is increasing for advanced methods to recover polyolefin resins such as polypropylene (PP) and polyethylene (PE), which constitute a large portion of plastic waste. Conventional methods dissolve these plastics in hydrocarbon solvents like xylene and then precipitate the polymers using a poor solvent, but xylene poses environmental and toxicity concerns, and such solvents are costly and difficult to scale for industrial use.

Description and Advantages

This invention provides a novel purification process in which recycled plastics are dissolved and precipitated under mild conditions using a low-environmental-impact, versatile solvent, allowing metals and other resin contaminants to be removed and high-purity PP and PE to be recovered [Fig. 1].

⮚Processing under mild conditions
Uses low-environmental-impact solvent capable of melting polyolefin waste plastics at 135-150 °C , allowing treatment below the solvent's boiling point.

⮚Separation of PP and PE
This process enables separation of PP and PE - previously considered difficult to achieve.

⮚Recovery of high-quality recycled plastics
The recovered PP and PE exhibit approximately fivefold improvement in tensile strength compared to conventional methods, along with significantly improved purity and transparency [Fig. 2].

Figure 1: Extraction process of recycled resin

Figure 2: Tensile test results (top) and X-ray CT images (bottom) before and after purification of recycled plastic