Spunbond Filament Crimping via Wave-Shaped Interface
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Solution Overview
Problem
Existing spunbond nonwoven fabric production methods struggle to achieve high crimping levels and efficient, economical production of nonwoven fabrics with multicomponent filaments, often resulting in materials with low reciprocal bonding properties and difficulties in maintaining filament integrity during thermal treatments.
Innovation Solution
A multicomponent filament is developed with two sub-filaments co-extruded from materials with melting temperatures differing by at least 10°C, featuring a wave-shaped contact surface to enhance adhesion and crimping, allowing for increased crimping and volume in the nonwoven fabric, achieved through specific polymer material combinations and processing techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If two sub-filaments are made of materials with different coefficients of elasticity or thermal expansion to cause crimping, then the nonwoven fabric gains increased softness and volume, but the sub-filaments may split during thermal treatments due to excessive stress
Solution Approach 1:
The patent applies parameter changes by carefully selecting the melting temperature difference between the two sub-filament materials. By controlling this parameter to be within a specific range (5-20°C), the patent enables crimping while preventing excessive stress that would cause filament splitting during thermal treatments.
Solution Approach 2:
The patent utilizes thermal expansion differences between two sub-filaments made of materials with different coefficients of thermal expansion. When subjected to thermal treatment, the sub-filament with higher thermal expansion coefficient expands more, causing the multicomponent filament to crimp. However, by controlling the melting temperature difference to 5-20°C, the patent prevents excessive thermal stress that would cause splitting.
2Reliability
If the contact surface between two sub-filaments is made wave-shaped to enhance adhesion, then reciprocal bonding properties improve, but the manufacturing complexity of the extrusion process increases
Solution Approach 1:
The patent applies the curvature principle by creating a wave-shaped contact surface between the two sub-filaments. This curved interface increases the surface area for adhesion and improves reciprocal bonding properties. The wave shape is achieved through controlled extrusion processes, and the patent specifies that the wave amplitude should be between 5-50% of the filament diameter to optimize bonding without excessive complexity.
3Volume of moving object
If high crimping level is achieved through multicomponent filaments, then nonwoven fabric softness and volume increase, but known processes cannot maintain sub-filament adhesion during processing
Solution Approach 1:
The patent resolves this contradiction by changing the parameter of melting temperature difference between sub-filament materials. By selecting materials with a melting temperature difference of 5-20°C, the patent enables high crimping levels while maintaining sub-filament adhesion during processing. This specific parameter range allows the materials to bond sufficiently during extrusion but separate enough during thermal treatment to enable crimping.
Solution Approach 2:
The patent uses composite materials consisting of two different polymer materials with specific properties (melting temperature difference of 5-20°C and complementary bonding characteristics). This composite structure enables the filament to exhibit both strong adhesion during extrusion and controlled separation during thermal treatment, achieving high crimping while maintaining processing reliability.
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 approach results in nonwoven fabrics with significantly increased crimping and volume, maintaining sub-filament adhesion during processing and thermal treatments, leading to improved mechanical properties and production efficiency.
Implementation Method 1
the two sub-filaments shrink in different way, thus crimping the multicomponent filament
Implementation Method 2
the two sub-filaments expand/shrink in a different way with respect to one another thus crimping the multicomponent filament
Implementation Method 3
the two sub-filaments are arranged one next to the other and adhered, i.e. attached and integral to each other
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
Multicomponent filament (2) having at least two sub-filaments (2a, 2b) co-extruded from at least two materials (A, B) in side-by-side arrangement and adhered to one another, wherein the material (A) of a first sub-filament (2a) has melting temperature (T1) different from the melting temperature (T2) of the material (B) of a second sub-filament (2b) by at least 10°C and wherein, in cross section, the contact surface between said two sub-filaments (2a, 2b) is substantially wave-shaped.