Extensible Nonwoven Facing Layer for Elastic Fabrics
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Solution Overview
Problem
Existing elastic nonwoven fabrics for applications like diapers face challenges with facing layers that are not extensible, leading to mechanical damage during high-speed stretch processes, and current solutions lack simplicity and high miscibility.
Innovation Solution
A nonwoven facing layer comprising polypropylene and a low ethylene content propylene-based elastomer, which provides high elongation and extensibility, with specific properties such as a MFR of less than 80 dg/min, triad tacticity of 75% or more, and comonomer-derived content within certain ranges, allowing for breathability and aesthetic appeal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If spunbond polypropylene nonwoven is used as facing layer, then aesthetic properties and structural stability are improved, but extensibility deteriorates causing mechanical damage during high-speed stretch process
Solution Approach 1:
The facing layer is constructed as a composite material combining polypropylene homopolymer or copolymer with propylene-α-olefin elastomer. This composite structure provides both the structural stability of polypropylene and the extensibility of the elastomer, allowing the fabric to withstand high-speed stretch processing without mechanical damage while maintaining aesthetic properties.
Solution Approach 2:
The invention changes the compositional parameters of the facing layer by incorporating specific amounts of propylene-α-olefin elastomer (5-30 wt%) with controlled molecular weight and comonomer content. This parameter modification enables the material to achieve both structural integrity and extensibility required for mechanical activation processes.
2Adaptability or versatility
If complex multi-component composition is used to achieve extensibility, then extensibility is improved, but formulation complexity increases
Solution Approach 1:
Instead of using complex multi-component formulations, the invention achieves extensibility by carefully controlling parameters within a simplified two-component system: polypropylene and propylene-α-olefin elastomer. The key is specifying precise ranges for elastomer molecular weight (MFR < 80 dg/min), comonomer content (5-18 wt%), and elastomer proportion (5-30 wt%), which simplifies formulation while maintaining high extensibility.
3Adaptability or versatility
If high elastomer content is used to achieve high elongation, then extensibility is improved, but miscibility with polypropylene deteriorates
Solution Approach 1:
The invention optimizes miscibility by controlling the chemical structure parameters of the elastomer component. Specifically, using propylene-α-olefin elastomers with limited comonomer content (5-18 wt%) and appropriate molecular weight ensures chemical compatibility with polypropylene. This allows high elastomer content (up to 30 wt%) for achieving high elongation while maintaining homogeneous mixing and compositional stability.
Data Source
AI summary
Disclosed is a multilayer fabric and a method of forming a multilayer fabric comprising one or more facing layers and one or more elastic layers adjacent to or sandwiched there between, the one or more facing layers comprising a polypropylene; and a propylene-α-olefin elastomer having and an MFR of less than 80 dg/min; wherein the facing layer is extensible and non-elastic and has a Handle-O-Meter value of less than 60 g and a 1% Secant Flexural Modulus of less than 1000 MPa. In certain embodiments, polyethylenes are absent from the facing layer(s).