Cold-Stretched Polyethylene Drawstring for Trash Receptacle Fit
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Solution Overview
Problem
Existing drawstring trash bags have limitations in securely affixing to a wide range of trash receptacle openings, particularly due to the use of expensive and bulky materials, and often require excessive force to stretch over larger openings, which affects their usability and manufacturing costs.
Innovation Solution
A drawstring bag design incorporating a combination of inelastic and elastic drawstrings, where the elastic drawstrings are made from a cold-stretched blend of LLDPE/LDPE and HDPE, respectively, allowing for a wider range of receptacle compatibility while maintaining cost-effectiveness and adequate lifting capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If expensive elastomeric materials are used for elastic drawstrings to improve gripping capability, then the bag can secure to trash receptacles, but manufacturing cost increases
Solution Approach 1:
The patent changes the material parameters by using cold-stretched polyethylene blends (LLDPE/LDPE) instead of expensive elastomeric materials. The cold-stretching process modifies the polyethylene to achieve elastic properties with reduced elongation at yield, providing gripping capability at lower cost
Solution Approach 2:
The patent uses composite material formulations combining LLDPE and LDPE in specific ratios to create a drawstring material that exhibits both elastic recovery and controlled elongation properties, replacing single-material elastomeric solutions
2Strength
If traditional high density polyethylene drawstrings are used to maintain tensile strength, then lifting capacity is sufficient, but adaptability to different receptacle sizes is limited
Solution Approach 1:
The patent applies cold-stretching to modify the polyethylene drawstring material, which reduces elongation at yield while maintaining tensile strength. This creates a material that can stretch to accommodate different receptacle sizes but will not over-extend, providing both adaptability and strength control
Solution Approach 2:
The patent creates local quality differences within the drawstring material by cold-stretching specific regions or the entire drawstring to achieve zones with different elastic properties, allowing the drawstring to adapt to various receptacle diameters while maintaining overall structural integrity
3Ease of manufacture
If cold-stretched polyethylene blends are used for drawstrings, then material cost is reduced and elongation at yield is controlled, but manufacturing process complexity increases
Solution Approach 1:
The patent performs cold-stretching of the polyethylene material in advance during the manufacturing process, before the drawstrings are assembled into bags. This preliminary action prepares the material with the desired elastic properties, simplifying subsequent assembly operations
Solution Approach 2:
The patent replaces traditional thermal stretching or elastomeric material processing with a cold-stretching mechanical process that directly deforms the polyethylene chains to create elastic properties, eliminating the need for heating equipment or specialized elastomer handling
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 enables the drawstring bag to securely fit over a broader range of trash receptacle openings with reduced effort, while maintaining sufficient strength to lift and carry full bags, utilizing common and cost-effective polyethylene materials.
Implementation Method 1
the elastic drawstrings are made from a cold-stretched blend of LLDPE/LDPE and HDPE, respectively
Data Source
AI summary
The present invention is directed to a drawstring bag comprising a first panel and a second panel. The first panel and the second panel are joined along a first side, a bottom, and a second side. The first panel and the second panel thereby define an upper opening of the bag. The drawstring bag may further comprise a first pair of drawstrings disposed within a first hem along the upper opening of the bag in the first panel and a second pair of drawstrings disposed within a second hem along the upper opening of the bag in the second panel. The first pair of drawstrings may comprise a shorter elastic drawstring and a longer inelastic drawstring.