Plastic Recycling Innovation: Evidence from Patent Portfolios and Convergence

Plastic recycling technologies are rapidly being reoriented toward process-, operations-, and quality-centered innovation, driven by the expansion of the circular economy and digital transformation. This study uses patent data to quantify long-term trends in plastic recycling and to compare technological structures and thematic shifts before and after 2015, thereby identifying core technological axes and convergence patterns. We collected and curated 64,639 triadic patents (2005–2024) and conducted IPC portfolio analysis, IPC co-occurrence network analysis, and period-split topic modeling. The results indicate that, since 2015, technologies related to data- and AI-enabled sorting, quality assurance, and process optimization (G06), along with tracking and connectivity (H04), collection and logistics (B65), water treatment (C02), and quality modification/compounding (C09), have expanded, while the relative prominence of some synthesis- and conversion-oriented technologies has declined. Convergence has shifted from material formulation–centered combinations toward stronger linkages with downstream processing–productization–standardization and operational infrastructure. Topic trends likewise show the rising salience of reuse-oriented packaging take-back, washing and standardization, remanufacturing, and data governance in the later period. Overall, these shifts suggest that recycling technologies are evolving beyond isolated process improvements toward maximizing circularity performance across the value chain, supporting sustainability objectives such as reducing environmental burdens and carbon emissions and improving resource efficiency.