Mono-Material Packaging Bag Sealing for Drop Durability
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Solution Overview
Problem
Packaging bags with composite films containing different resins face challenges in recycling due to weakened bond strength and durability issues, particularly when dropped, as they are not mono-material.
Innovation Solution
A packaging bag design where the bottom member is folded in half and sandwiched between body members, with body and bottom seal portions using polyethylene-based resin layers, and a convex shape at the boundary portions to enhance durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If composite films with different resins (PET base material + PE sealant) are used for body members and bottom member, then heat bonding strength is improved, but recyclability deteriorates
Solution Approach 1:
The patent applies homogeneity by using the same polyethylene-based resin for both the body members and bottom member films. This single-resin approach enables easy recycling while maintaining sufficient heat bonding strength through optimized resin selection and sealing structure design, resolving the contradiction between bonding strength and recyclability.
2Adaptability or versatility
If the same kind of resin as sealant is laminated as base material in composite films, then recyclability is improved, but strength and durability at heat-bonded parts deteriorate
Solution Approach 1:
The patent changes the parameters of the polyethylene-based resin, specifically using linear low-density polyethylene (LLDPE) with controlled density (0.915-0.940 g/cm³) and molecular weight. This parameter optimization ensures adequate strength at heat-bonded portions while maintaining mono-material recyclability, resolving the contradiction between durability and recyclability.
3Reliability
If a convex shape is formed at the boundary portion of the bottom seal portion, then durability upon dropping is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies curvature by forming a convex shape at the boundary portion of the bottom seal portion. This curved structure distributes stress during dropping, preventing concentration at sharp corners and improving durability. The convex shape is integrated into the sealing process, minimizing additional manufacturing complexity while achieving enhanced reliability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design provides a mono-material packaging bag with improved durability and impact resistance, preventing disjoining and damage even when dropped.
Implementation Method 1
When heat bonding is performed between the body members or between the body members and the bottom member, inner surfaces of a composite film are joined to each other by melting the sealant.
Data Source
AI summary
A packaging bag has a bottom member folded in half along a folding line and sandwiched between two body members. Body seal portions with surfaces of the body members joined along left and right circumferential edge portions of the packaging bag are formed on a side above the folding line. A bottom seal portion with an inner surface of the bottom member joined to the inner surfaces of the body members is formed on a side below the folding line. An unsealed portion surrounded by the body seal portions and the bottom seal portion accommodates a content. Resin layers of the body members and the bottom member are formed of a polyethylene-based resin film. Boundary portions between the bottom seal portion and the unsealed portion have a convex shape toward the upper side of the packaging bag near a part in contact with the body seal portions.