Liquid-Tight Slide Fastener Core Thread Coating
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Solution Overview
Problem
Conventional slide fasteners with waterproof properties suffer from gaps between liquid-tight layers, allowing water to invade through the joint portions, especially under stress or deformation, which compromises their water repellent performance.
Innovation Solution
A liquid-tight slide fastener design where the core thread is coated with a water or oil repellent agent, and the coupling element rows and fastener tapes are also treated, preventing water or oil from penetrating through the joint portions by repelling it and maintaining it in the space between the liquid-tight layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If liquid-tight layers are bonded on the fastener tape surface, then water repellency is improved, but gaps remain at the joint portions allowing water invasion
Solution Approach 1:
A water stop flap is introduced as an intermediary component between the liquid-tight layers. This flap extends from one liquid-tight layer to overlap the joint portion and reach the other liquid-tight layer, creating an additional barrier that prevents water from invading through the gaps at the joint portions where the liquid-tight layers meet.
Solution Approach 2:
The water stop flap adds a dimensional extension to the liquid-tight layer structure. By extending the flap beyond the edge of the fastener tape in the lateral direction, the protection is extended into a new spatial dimension, covering the gap area that would otherwise be exposed at the joint portions.
2Reliability
If a water stop flap is added to prevent water invasion, then water repellency is improved, but device complexity increases
Solution Approach 1:
The water stop flap is merged with the existing liquid-tight layer structure. The flap is formed as an extension of the liquid-tight layer material itself, integrating the water stop function into the existing waterproofing system rather than adding a completely separate component, thereby reducing overall structural complexity.
Solution Approach 2:
The water stop flap serves multiple functions: it acts as both an extension of the liquid-tight layer for waterproofing and as a barrier element for preventing water invasion at the joint portions. This multi-functionality reduces the need for additional separate components, simplifying the overall device structure.
3Adaptability or versatility
If the fastener is subjected to lateral pulling force or deformation, then the gap at the joint portion widens, but water repellency deteriorates
Solution Approach 1:
The water stop flap is positioned in advance to overlap the joint portion before any deformation occurs. When lateral pulling forces or deformation cause the liquid-tight layers to separate and create gaps, the pre-positioned water stop flap maintains continuous coverage, cushioning against the widening gaps and preventing water invasion even under stressed conditions.
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
This design enhances water and oil repellency without the need for a water stop flap, maintaining effectiveness even under stress or deformation, and improves manufacturing efficiency by ensuring water or oil remains deposited between the layers, preventing further invasion.
Implementation Method 1
the core thread is coated with a water repellent agent or an oil repellent agent... preventing water or oil from penetrating through the joint portions by repelling it
Data Source
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AI summary
A liquid-tight slide fastener (10), wherein a pair of right and left coil-like coupling element rows (12), through which a core thread (14) is respectively passed, is attached by sewing along opposing side edges of a pair of right and left fastener tapes (16), the fastener tapes (16) having a liquid-tight layer (18) on one surface thereof, and the core thread (14) is coated with a water repellent agent or oil repellent agent (62). Consequently, even if water or oil invades into a space portion in the coupling element rows (12) through a joint portion in the liquid-tight slide fastener (10), the core thread (14) repels the water or oil, thereby blocking a further invasion of water or oil, and exerting excellent water repellency or oil repellency without provision of a water stop flap.