Multilayer Stretchy Drawstring for Trash Bags
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Solution Overview
Problem
Conventional elastic drawstring bags require thicker and more expensive materials to achieve the desired balance of elasticity and strength, with manufacturing complexities and safety hazards associated with highly stretched elastic bands, while existing solutions are either too elastic or stiff for practical use in trash containers.
Innovation Solution
A multilayer stretchy drawstring comprising a first layer of elastomeric polymer and two thermoplastic polymer layers, each stretched beyond its deformation limit and allowed to elastically recover, providing a balanced elasticity and strength suitable for securing trash bags without excessive thickness or cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a single layer of elastomers or blended copolymers is used to create an elastic drawstring, then the drawstring achieves desired elasticity to naturally contract and secure the bag, but the drawstring becomes 50% to 200% thicker and more expensive to produce
Solution Approach 1:
The patent applies composite materials by combining an elastomeric core layer with thermoplastic skin layers to create a multilayer laminate. This composite structure allows the drawstring to achieve the desired elasticity from the elastomeric core while the thin thermoplastic skin layers (0.5-2.0 mils each) prevent excessive thickness, solving the contradiction between elasticity and thickness.
Solution Approach 2:
The patent applies local quality by assigning different functions to different layers: the elastomeric core layer provides elasticity and recovery, while the thin thermoplastic skin layers provide structural integrity and control thickness. This localized functional distribution allows the drawstring to be elastic without being excessively thick.
2Strength
If conventional laminate structures with folded plastic layers and elastic layers are used, then the drawstring achieves balanced mechanical properties, but the manufacturing process becomes complex and seal strength between layers becomes difficult to achieve
Solution Approach 1:
The patent merges the elastomeric layer and thermoplastic layers into a single multilayer laminate structure that is coextruded as one integrated component. This combining of layers into a unified structure simplifies manufacturing by eliminating the need for separate lamination and folding steps, while maintaining the balanced mechanical properties through proper layer design.
Solution Approach 2:
The patent replaces complex mechanical lamination and folding processes with a coextrusion process that creates the multilayer structure in a single step. This substitution of manufacturing methodology reduces process complexity while achieving the same functional result of combining elastomeric and thermoplastic properties.
3Ease of operation
If the elastic loop is placed in a highly stretched state when the bag is open, then the bag automatically closes when removed from the receptacle, but manufacturing becomes difficult and expensive and safety hazards arise
Solution Approach 1:
The patent applies preliminary action by pre-setting the multilayer laminate with controlled elasticity during manufacturing, so that the drawstring naturally contracts to secure the bag without requiring the bag to be manufactured in a highly stretched state. This preliminary configuration of elastic properties eliminates the need for complex post-manufacturing stretching processes.
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 drawstring achieves a balanced stretch-to-strength performance, allowing secure fitting around trash receptacles while maintaining a smooth surface and economical manufacturing, addressing the limitations of prior solutions by minimizing buckling and texturing, thus enhancing usability and safety.
Implementation Method 1
a first layer of elastomeric polymer, a second layer of thermoplastic polymer, and a third layer of thermoplastic polymer... the drawstring is stretched beyond the deformation limit of the thermoplastic polymer of the second layer and the third layer respectively, and allowed to elastically recover
Implementation Method 2
the thermoplastic polymer of the second layer and of the third layer each having a deformation limit, the second layer and the third layer being disposed on opposite sides of the first layer, and the drawstring is stretched beyond the deformation limit of the thermoplastic polymer
Data Source
AI summary
The disclosed subject matter relates to a multilayer stretchy drawstring and methods of making the same. The drawstring of the disclosed subject matter is a stretched multilayer coextruded or laminated film that offers good balance between easy stretching at low strain and high strain hardening at high strain. The multilayer film includes a first layer of elastomeric polymer and second and third layers of thermoplastic polymer and is stretched beyond the deformation limit of the thermoplastic polymer and allowed to recover. This novel drawstring can be incorporated into a bag to enable the bag to be securely fitted to the upper portion of a trash container while not interfering with the intrinsic strength and operation of the drawstring.