Single Polymer Bicomponent Filament for Nonwoven Fabric
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Solution Overview
Problem
Existing nonwoven fabrics produced through area bonding require two separate polymer compositions, increasing processing complexity and making recycling difficult, while also limiting temperature usage due to the lower melting point of the binder component.
Innovation Solution
A continuous bicomponent filament formed from a single polymer system with a semi-crystalline polymer resin that undergoes stress-induced crystallization, where a partially crystalline matrix component and an amorphous binder component exhibit a single melting peak, allowing thermal bonding at lower temperatures without the need for additional binder resins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two separate polymer compositions are used for area bonding, then bonding functionality is achieved, but processing complexity increases and recycling becomes difficult
Solution Approach 1:
The patent merges the matrix component and binder component into a single bicomponent filament structure. The first polymer component forms the matrix while the second polymer component forms the binder, both within the same filament. This integration eliminates the need for separate polymer compositions and simplifies processing while maintaining area bonding functionality through thermal melting of the binder component.
Solution Approach 2:
The patent segments the filament cross-section into distinct functional regions: the first polymer component (matrix) and the second polymer component (binder). This segmentation is achieved through specific geometric configurations such as the binder occupying the central region or specific portions of the cross-section, allowing each component to perform its designated function while being part of a unified structure.
2Reliability
If two separate polymer compositions are used for area bonding, then bonding functionality is achieved, but recycling and reuse of scrap material becomes difficult
Solution Approach 1:
By combining both the matrix and binder functions within a single bicomponent filament made from compatible polymer compositions, the patent enables simplified recycling. The filaments can be processed together through melting and reformation, allowing scrap material to be readily reused without the complications of separating or handling multiple different polymer types.
3Reliability
If a lower melting point binder component is used, then area bonding is enabled, but the maximum operating temperature of the nonwoven fabric is limited
Solution Approach 1:
The patent applies local quality by assigning different thermal properties to different regions of the filament cross-section. The binder component (second polymer) is positioned in specific regions and has a lower melting point to enable area bonding, while the matrix component (first polymer) constitutes the bulk structure and provides the higher temperature operational characteristics. This spatial differentiation of properties allows the fabric to bond at lower temperatures while maintaining structural integrity at higher operating temperatures.
4Reliability
If point bonding is used with same polymer composition, then bonding is effective, but area bonding becomes unusable
Solution Approach 1:
The bicomponent filament structure enables area bonding by providing a distributed binder component throughout the fabric structure. The second polymer component is positioned to be exposed at the fabric surface or distributed throughout, allowing thermal energy to melt and bond large areas uniformly rather than requiring discrete point contact, thus expanding bonding method versatility.
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 approach simplifies the manufacturing process, reduces costs, and enables the use of nonwoven fabrics at higher temperatures by using a single polymer system for both strength and bonding, while maintaining desirable physical properties like tensile and tear strength.
Implementation Method 1
the present invention uses a semi-crystalline polymer resin system that undergoes stress-induced crystallization in the fiber spinning process
Implementation Method 2
the binder component of the continuous bicomponent filament has crystalized during a thermal bonding step
Data Source
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AI summary
A nonwoven fabric is provided having a plurality of semi-crystalline filaments that are thermally bonded to each other and are formed of the same polymer and exhibit substantially the same melting temperature. The fabric is produced by melt spinning an amorphous crystallizable polymer to form two components having different levels of crystallinity. During spinning, a first component of the polymer is exposed to conditions that result in stress-induced crystallization such that the first polymer component is in a semi-crystalline state and serves as the matrix or strength component of the fabric. The second polymer component is not subjected to stress induced crystallization and thus remains in a substantially amorphous state which bonds well at relatively low temperatures. In a bonding step, the fabric is heated to soften and fuse the binder component. Under these conditions, the binder component undergoes thermal crystallization so that in the final product, both polymer components are semi-crys talline.