Multilayer Draw Tape for Trash Liners
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Solution Overview
Problem
Existing draw tape bags for trash liners face challenges in strength and sealability, particularly when used with relatively thin pliable materials, as they tend to be prone to tearing and inadequate heat sealing.
Innovation Solution
A multilayer draw tape structure is introduced, featuring a polypropylene core with propylene-ethylene copolymer outer layers, produced using a slot cast extrusion process, which enhances strength and sealability by incorporating a polypropylene core with greater than 80% polypropylene and outer layers comprising 8% to 30% ethylene, and is integrated into the bag via side seals and hem notches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a simple single-layer draw tape is used, then the manufacturing cost is low and the process is simple, but the strength and sealability are insufficient causing tearing and inadequate heat sealing
Solution Approach 1:
The patent applies composite materials by constructing the draw tape with multiple layers of different thermoplastic materials. The multilayer structure combines materials with different properties to achieve both high strength and good sealability, resolving the contradiction between strength and structural complexity.
Solution Approach 2:
The patent applies local quality by giving different layers of the draw tape different material compositions and properties. The outer layers may have different melting points or chemical compositions than the core layer, allowing each layer to perform its specific function optimally while together providing both strength and sealability.
2Reliability
If a multilayer draw tape structure is implemented, then the strength and sealability are improved, but the manufacturing complexity increases
Solution Approach 1:
The patent applies parameter changes by carefully selecting and controlling the material composition, thickness, and thermal properties of each layer in the multilayer draw tape. By optimizing these parameters, the tape achieves reliable heat sealability while the manufacturing process remains manageable through standardized production techniques.
3Strength
If thin pliable bag materials are used, then the bag is flexible and easy to handle, but the draw tape attachment strength is reduced leading to tearing
Solution Approach 1:
The patent applies composite materials in the draw tape construction to distribute mechanical stresses across multiple layers. This multilayer composite structure provides enhanced attachment strength to thin pliable bag materials without compromising the bag's flexibility, as the draw tape itself remains compliant while providing superior bonding capability.
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 multilayer draw tape structure significantly improves the strength and sealability of the bag, allowing for reliable closure and handling of trash liners without tearing, while maintaining heat sealability and ease of use.
Implementation Method 1
produced using a slot cast extrusion process
Implementation Method 2
maintaining heat sealability
Data Source
AI summary
The bag includes a draw tape that may be used to cinch closed the opening of the bag. The draw tape is multilayer with a polypropylene core and propylene-ethylene copolymer or other suitable polymers in the outer layers.