Recycling-oriented Structural Design and Research of PET Mono-Material Caps

LING Shengyu; LI Juan; HU Changhong; YANG Jihong

doi:10.19554/j.cnki.1001-3563.2026.17.002

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Packaging Engineering ›› 2026, Vol. 47 ›› Issue (17) : 11-17. DOI: 10.19554/j.cnki.1001-3563.2026.17.002

Special Topic on Sustainable Design and Systemic Transformation of Plastic Packaging for Liquid Foods

Recycling-oriented Structural Design and Research of PET Mono-Material Caps

LING Shengyu^*, LI Juan, HU Changhong, YANG Jihong

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Abstract

Currently, most drinking water bottle caps are made of HDPE, while the bottle bodies are made of PET. This material mismatch creates difficulties in recycling sorting and leads to a low recycling rate. The work aims to develop an integrated cap structure that fully matches PET bottle bodies, to promote the transition of drinking water packaging to full-PET mono-material design, and meet the industry demand for packaging circularity. In this study, the property differences between PET and HDPE were compared to identify the technical bottlenecks of applying PET to bottle cap manufacturing. Then, iterative structural optimization was carried out on three core modules: thread structure, sealing interference fit, and the tamper-evident ring with dual performance requirements of breakage resistance during assembly and brittle fracture on opening.Validation results showed that the one-step injection molding process for the tamper-evident ring and cap body, combined with optimized sealing and anti-pull-off structures, effectively compensated for the inherent brittleness of PET. This design reduced fracture failure risk, improved sealing reliability, and solved the key technical barrier of applying PET in drinking water bottle caps. Through structural innovation, mass production of PET drinking water bottle caps can be realized. The full-PET mono-material design keeps the packaging free of mixed materials, complies with regulatory requirements for recyclable, single-component packaging, and effectively cuts down beverage packaging recycling costs. It also provides a technical reference for the recycling-oriented structural upgrade of similar beverage packaging products.

Key words

PET drinking water bottle cap / mono-material packaging / bottle cap structural design / tamper-evident ring / recycling and regeneration

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LING Shengyu, LI Juan, HU Changhong, YANG Jihong. Recycling-oriented Structural Design and Research of PET Mono-Material Caps[J]. Packaging Engineering. 2026, 47(17): 11-17 https://doi.org/10.19554/j.cnki.1001-3563.2026.17.002

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