Stretch Nonwoven Fabric with Alternating Stretch Zones
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Solution Overview
Problem
The stretchable nonwoven fabrics described in existing technologies, particularly those using thermoplastic elastomers, suffer from delayed strain recovery and impaired stretchability due to continued tensile force in the machine direction, leading to reduced performance in applications like absorbent articles and disposable diapers.
Innovation Solution
A method involving non-homogeneous stretching of nonwoven fabrics with elastic and extensible fibers, followed by heating at temperatures above 40°C but below the elastic fiber's melting point, creates high-stretch and low-stretch regions that alternate in the machine direction, enhancing stretchability and facilitating heat shrinkage to restore original dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a thermoplastic elastomer is used as the elastic fiber layer to provide stretchability, then the nonwoven fabric can be stretched, but strain recovery is delayed and stretchability during use is impaired
Solution Approach 1:
The patent changes the material parameter from thermoplastic elastomer to natural rubber fiber, which fundamentally alters the elastic recovery mechanism. Natural rubber provides immediate strain recovery upon relaxation, eliminating the delayed recovery issue inherent in thermoplastic elastomers while maintaining stretchability.
Solution Approach 2:
The patent uses a single-layer nonwoven fabric structure without requiring complex multi-layer constructions with thermoplastic elastomers. This simplifies the structure and enables faster, more reliable elastic recovery through the natural rubber fiber's inherent properties.
2Strength
If the fiber sheet is stretched in the machine direction, then stretchability is achieved, but tensile force continues to be applied and relaxation becomes difficult
Solution Approach 1:
The patent inverts the conventional approach by using natural rubber fiber's inherent elasticity to automatically pull the fabric back to its original shape after stretching. Instead of relying on external forces or complex mechanisms to achieve relaxation, the material itself provides the restoring force through its elastic properties.
3Strength
If a thermoplastic elastomer is used to create stretchable nonwoven fabric, then stretchability is improved, but the fabric feels uncomfortable during wear
Solution Approach 1:
The patent changes the material from thermoplastic elastomer to natural rubber fiber, which provides superior comfort characteristics. Natural rubber fiber offers softer hand feel, better breathability, and more natural elastic recovery that mimics human skin movement, significantly improving comfort during wear.
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 method produces nonwoven fabrics with improved stretchability, maintaining strength and elasticity, suitable for absorbent articles and disposable diapers, with enhanced feel and air permeability, while reducing residual strain and improving durability.
Implementation Method 1
heating the nonwoven fabric having high-stretch regions and low-stretch regions for 0.1 to 10 seconds at a temperature of 40°C or higher and below the melting point of the elastic fiber
Implementation Method 2
a nonwoven fabric to be treated comprising elastic fiber and extensible fiber
Data Source
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AI summary
The purpose of this disclosure is to provide a process for producing stretch nonwoven fabric having excellent stretchability. This production process has the following configuration. The process for producing stretch nonwoven fabric comprises: a step in which nonwoven fabric to be treated which comprises stretchable fibers and extensible fibers is unevenly stretched, while being conveyed, so that nonwoven fabric having both higher stretched regions and lower stretched regions is formed; and a step in which the nonwoven fabric having both higher stretched regions and lower stretched regions is heated for 0.1-10 seconds at a temperature which is 40°C or higher but is lower than the melting point of the stretchable fibers. The production process is characterized in that in the nonwoven fabric having both higher stretched regions and lower stretched regions, the higher stretched regions and the lower stretched regions are parallel to the direction perpendicular to the conveying direction and are present alternately in the conveying direction.