Pulp-Molded Container Fluid Seal via Channel-Protrusion Geometry
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Solution Overview
Problem
Molded pulp containers face challenges in achieving a suitable fluid seal without mold-lock or tearing, and adding plastic to address these issues compromises their biodegradable characteristics.
Innovation Solution
The use of a tray and cover design with a channel and protrusion system, where the protrusion is biased against the channel walls to form a fluid seal, combined with tamper-resistant and tamper-evident features, achieves a fluid seal without the need for plastic and prevents mold-lock or tearing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fluid seal structure (shoulder and undercut) is added to molded pulp containers, then sealing reliability is improved, but the container may experience mold-lock or tearing during removal
Solution Approach 1:
The sealing structure is divided into two separate components: a shoulder on the tray and an undercut on the cover. This segmentation allows each component to perform its sealing function independently without creating mold-lock conditions that would cause tearing during removal.
Solution Approach 2:
The interface between the shoulder and undercut acts as an intermediary sealing mechanism that provides fluid seal reliability without requiring the container material to flex or stretch during removal, thus preventing tearing while maintaining seal integrity.
2Reliability
If plastic is added to molded pulp containers to improve seal and prevent tearing, then reliability and strength are improved, but biodegradability is compromised
Solution Approach 1:
The invention changes the design parameters of the sealing structure from material-dependent (requiring plastic additives for flexibility) to geometry-dependent (using shoulder and undercut shapes that provide sealing through form rather than material properties). This allows pure pulp fiber containers to achieve reliable sealing without compromising biodegradability.
3Ease of manufacture
If traditional injection molding or thermoforming processes are used for plastic containers, then ease of manufacture is improved, but environmental sustainability deteriorates
Solution Approach 1:
The invention replaces traditional plastic injection molding or thermoforming processes with molded pulp manufacturing that uses integrated shoulder and undercut features. This substitution maintains manufacturing efficiency while eliminating the need for plastic materials, thereby improving environmental sustainability without sacrificing ease of manufacture.
Data Source
AI summary
Aspects of the present disclosure relate to a pulp-molded container comprising a tray comprising a bottom wall, a peripheral side wall extending upwardly from the bottom wall and terminating in a flange that at least partially defines an open top, the flange having a channel defined by spaced inner and outer channel walls connected by a bottom channel wall; and a cover closing the open top in a closed configuration, the cover including a protrusion biased against the inner and outer channel walls.