Functional Nonwoven Fabric with Segmented Fibers for Air Permeability
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Solution Overview
Problem
Conventional functional nonwoven fabrics face issues such as decreased air permeability due to clogging and uneven distribution of functional particles, especially when large particles are used, and thermally expandable materials exhibit slow and uneven expansion, delaying temperature rise and insulation effects.
Innovation Solution
A functional nonwoven fabric with long fibers having alternating large and small diameter portions, where the small diameter portions are monofilaments, and functional particles are integrated into the large diameter portions, allowing for uniform dispersion and quick expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If functional particles are supported on nonwoven fabric using binder to prevent particle fallout, then particle retention is improved, but air permeability deteriorates due to clogging of the nonwoven fabric
Solution Approach 1:
The fiber is divided into multiple diameter portions along its length, with small diameter portions providing particle support and large diameter portions maintaining porosity. This segmentation allows different sections of the same fiber to fulfill different functions simultaneously.
Solution Approach 2:
Different portions of the fiber have different local properties: small diameter portions are optimized for particle adhesion while large diameter portions are optimized for maintaining air flow channels. This local differentiation resolves the contradiction between particle retention and air permeability.
2Quantity of substance
If large amount of functional particles are supported on nonwoven fabric, then functional performance is improved, but air permeability deteriorates due to particle deposition between fibers
Solution Approach 1:
By segmenting the fiber into small and large diameter portions, the structure provides designated zones (small portions) for particle accumulation while preserving open channels (large portions) for air flow, allowing high particle loading without permeability loss.
Solution Approach 2:
The solution moves from a two-dimensional surface deposition problem to a three-dimensional structured fiber design, where particles are confined to specific segments along the fiber length, preventing them from blocking the entire cross-section and maintaining air permeability.
3Ease of manufacture
If functional particles are supported on nonwoven fabric surface, then particle application is simplified, but uniform dispersion deteriorates as particles concentrate on the supply side surface
Solution Approach 1:
The segmented fiber structure with alternating small and large diameter portions creates multiple particle capture zones along the fiber length, distributing particles more uniformly throughout the nonwoven fabric thickness rather than concentrating them on one surface.
4Reliability
If conventional thermally expandable materials are used in ventilation holes, then fire resistance is achieved, but expansion speed deteriorates causing delayed temperature rise and insulation effects
Solution Approach 1:
The thin film of binder material surrounding the thermally expandable particles allows rapid heat penetration and quick particle expansion. The minimal binder thickness reduces thermal resistance, enabling fast response to fire conditions.
Solution Approach 2:
By reducing the binder content and thickness to minimal levels, the thermal parameters (heat transfer rate, expansion speed) are significantly improved, allowing the thermally expandable particles to respond rapidly to temperature increases during fire events.
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 fabric maintains air permeability and prevents particle fallout even with increased particle blending, and thermally expandable fibers quickly respond to high temperatures, blocking airflow as needed.
Implementation Method 1
The functional particles having thermal expansion properties, such as thermally expandable graphite, absorb heat and expand, for example, when exposed to high temperatures
Implementation Method 2
it is possible to make a structure in which holes are drilled in ceiling panels of a building to allow air to pass therethrough under normal circumstances
Data Source
Figure 1~2
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AI summary
The problem addressed by the present invention is to suppress a decrease in air permeability of a nonwoven fabric while suppressing falling off of functional particles. The means for solving the problem of the present invention is that a functional nonwoven fabric 1 is formed to contain long fibers made of synthetic resin and integrated with functional particles 4, 4 having a predetermined function. A diameter of the long fiber changes in a longitudinal direction of the fibers so that a plurality of large diameter portions 2, 2 and a plurality of small diameter portions 3, 3 are alternately arranged. The small diameter portions 3, 3 are monofilaments formed of the synthetic resin. At least a part of the large diameter portions 2, 2 contain the functional particle 4. A fiber diameter of the small diameter portions 3, 3 is equal to or smaller than a diameter of the functional particles 4, 4 contained in the large diameter portions 2, 2.