Case study

Sealing behaviour of PLA/paper coffee capsule lids

  • Reading time 1 min

  1. Project objective

    Identify the root causes of different sealing behaviours observed in two apparently identical PLA/paper-based coffee capsule lid materials.

  2. Year

    2020

  3. Lab/Division

    OPENLab site
    Lugano
    IMA division/company involved
    IMA Coffee

Project overview

Two PLA/paper-based lid materials, nominally identical, exhibited significantly different sealing behaviour during production.
Microscopic surface analysis revealed a morphological difference in the non-woven layer: larger openings in one material exposed the underlying paper layer, creating discontinuities at the sealing interface. This structural difference negatively affected sealing performance.
Heat seal tests confirmed the different behaviours, while microscopy provided a clear explanation of the root cause.

Key results

  • Identification of variability in the non-woven layer as the primary cause of sealing issues.
  • Corrective action by the packaging supplier to improve quality control of non-woven raw materials used in paper lamination.