Repulpable Bag Zipper Structure for Reclosability and Composting
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Solution Overview
Problem
Plastic bags with zippers degrade slowly due to the thickness difference between the film and zipper flanges, leading to increased plastic waste and the need for improved biodegradability, recyclability, and repulpability.
Innovation Solution
A zipper for reclosable bags is formed with air cavities and a cellulose-based filler, which can be foamed to enhance solubility and reduce polymeric binder use, allowing for increased flexibility and stiffness adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a zipper with flanges is added to a plastic bag, then the reclosable function is improved, but the biodegradability and repulpability deteriorate due to increased thickness and slower degradation
Solution Approach 1:
The patent changes the physical and chemical parameters of the zipper material by incorporating cellulose-based fillers (wood fiber, cotton fiber, hemp fiber, flax fiber, or a combination thereof) into the polymeric binder matrix. This parameter change reduces the zipper's thickness and increases its biodegradability and repulpability while maintaining the reclosable function through the interlocking element mechanism
Solution Approach 2:
The patent creates a composite material system combining a polymeric binder with cellulose-based fillers to form the zipper. This composite structure allows the zipper to maintain mechanical functionality for reclosing while achieving improved biodegradability and repulpability, as the cellulose fibers can be repulped and the polymeric binder can biodegrade
2Reliability
If the zipper material thickness is reduced to improve degradation, then the biodegradability is improved, but the structural strength and durability deteriorate
Solution Approach 1:
The patent optimizes the ratio and type of cellulose-based fillers used in the zipper material to achieve the right balance between thickness reduction for biodegradability and sufficient structural strength through the filler network within the polymeric binder matrix
Solution Approach 2:
The patent applies different filler types and concentrations to different portions of the zipper structure, with higher filler content in areas requiring strength and lower content in areas where biodegradability is prioritized, creating local quality variations that satisfy both requirements
3Ease of manufacture
If conventional plastic materials are used for the zipper, then the manufacturing ease and durability are improved, but the environmental harm increases due to slow biodegradation and plastic waste
Solution Approach 1:
The patent changes the material composition parameters by replacing conventional pure plastic materials with a composite of polymeric binder and cellulose-based fillers, enabling the zipper to biodegrade and repulp while maintaining ease of manufacture through existing extrusion and forming processes
Solution Approach 2:
The patent utilizes the porous structure of cellulose-based fillers within the zipper material to enhance biodegradability and repulpability, as the porous structure allows for easier degradation and fiber separation compared to dense conventional plastics
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 zipper exhibits enhanced biodegradability, recyclability, and repulpability, meeting standards set by the Flexible Box Associations, with faster composting times and reduced plastic waste.
Implementation Method 1
the air cavities are formed through foaming
Implementation Method 2
the zipper exhibits enhanced biodegradability, recyclability, and repulpability, meeting standards set by the Flexible Box Associations, with faster composting times
Data Source
AI summary
A zipper for a reclosable bag includes a first interlocking element, and a second interlocking element. The first interlocking element and the second interlocking element are configured to cooperate to selectively open and close the zipper. One or both of the first interlocking element and the second interlocking element are formed of at least 85% repulpable material.