Non-Linear Seals for Stretchable Film Bag Integrity
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Solution Overview
Problem
Existing plastic bags with static seals fail to maintain integrity and performance when subjected to elongation during use, leading to issues like pin holes and tears due to differential deformation between the seal and the bag material.
Innovation Solution
Designing plastic bags with longer seals that have a non-linear configuration, allowing them to elongate consistently with the bag material, thereby maintaining strength and integrity under load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a static seal is used to provide strong sealing, then the seal strength is improved, but the seal integrity deteriorates when the bag elongates
Solution Approach 1:
The seal is designed with a non-linear configuration (such as zigzag, serpentine, or sinusoidal patterns) that allows it to dynamically deform and elongate along with the bag material. This dynamic capability enables the seal to maintain its sealing function while accommodating the elastic deformation of the bag body, resolving the contradiction between initial seal strength and integrity under elongation.
Solution Approach 2:
The seal geometry is modified by changing its configuration from a straight linear pattern to a non-linear pattern with specific geometric parameters (amplitude, wavelength, density). These parameter changes allow the seal to have an effectively longer path length that can accommodate greater elongation while maintaining structural integrity and sealing performance.
2Reliability
If the seal is made longer to accommodate elongation, then the seal integrity under load is improved, but the manufacturing complexity increases
Solution Approach 1:
The seal is divided into multiple repeating geometric patterns (such as zigzag segments or sinusoidal waves) that can be systematically generated during manufacturing. This segmentation allows the complex non-linear configuration to be created through repeated application of a simple geometric rule, reducing the actual manufacturing complexity despite the increased seal path length.
Solution Approach 2:
The seal incorporates curved geometric patterns (zigzag, serpentine, or sinusoidal shapes) that can be efficiently manufactured using standard sealing equipment. The curvature of these patterns provides the necessary elongation accommodation while the patterns remain within the capabilities of conventional heat sealing or ultrasonic sealing processes, avoiding the need for complex specialized equipment.
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 longer, non-linear seals ensure that both the seal and surrounding film structure maintain their strength and integrity even when the bag elongates, preventing structural failure and leakage.
Implementation Method 1
the plastic film is able to elongate, or stretch, while also substantially maintaining its strength and integrity
Implementation Method 2
the side seals are typically created by melting, or welding, the plastic layers, or films, of the bag together
Data Source
AI summary
In one example, a plastic product such as a plastic bag includes one or more seals. One of the seals includes respective portions of first and second plastic films that are arranged one on top of the other. The respective portions are joined together and are aligned generally parallel to a direction of elongation associated with the plastic films, where the direction of elongation is a direction in which the plastic films elongate when under load. As well, the respective portions extend along a length of the joined plastic films and have a length that is greater than a length of the plastic films.