PLA Nonwoven Fabric with Cross-Direction Bonding for Hygiene
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Solution Overview
Problem
Existing nonwoven fabrics for absorbent articles face challenges in achieving a balance between drapability, softness, and mechanical strength, particularly when using biodegradable polylactic acid (PLA) fibers, which often result in high stiffness and low softness, limiting their usefulness in hygiene products.
Innovation Solution
A nonwoven fabric with a specific pattern of alternating bonded and non-bonded areas, where the bonded areas are arranged in the cross direction as rods, ensuring no uninterrupted regions in the machine direction and continuous regions in the cross direction, utilizing polylactic acid-containing fibers with a high percentage of biodegradable content, enhancing drapability and tensile strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If polylactic acid (PLA) fibers are used in nonwoven fabrics, then biodegradability is improved, but stiffness increases and softness decreases
Solution Approach 1:
The patent applies local quality by creating a bonding pattern with differentiated regions: bonded areas provide mechanical strength and stability, while non-bonded areas maintain fiber flexibility and softness. This localized differentiation allows the fabric to exhibit both stiffness where needed for structure and softness where needed for comfort, resolving the contradiction between PLA biodegradability and fabric softness.
Solution Approach 2:
The bonding pattern is segmented into discrete bonded areas and non-bonded areas rather than uniform bonding. This segmentation allows different regions to fulfill different functions: bonded areas provide tensile strength and dimensional stability, while non-bonded areas contribute to drapability and softness, thereby resolving the contradiction between stiffness and softness in PLA-based nonwoven fabrics.
2Stability of the object's composition
If conventional bonding patterns are used in PLA nonwovens, then mechanical stability is improved, but drapability decreases
Solution Approach 1:
The patent employs an asymmetric bonding pattern where bonded areas are distributed non-uniformly across the fabric structure. This asymmetric arrangement creates a balance between regions requiring mechanical stability and regions requiring drapability, allowing the fabric to maintain structural integrity while exhibiting good drape and flexibility, thus resolving the contradiction between mechanical stability and drapability.
Solution Approach 2:
The bonding pattern extends in multiple dimensions with bonded areas arranged in specific geometric configurations (e.g., interconnected nodes and strands). This multi-dimensional arrangement provides mechanical stability through the bonded network while leaving three-dimensional non-bonded spaces that enable fiber movement and fabric drape, resolving the contradiction between mechanical stability and drapability.
3Strength
If softer polymers are increased in bi-component fibers, then softness is improved, but degradability decreases
Solution Approach 1:
The patent optimizes the ratio and composition of polymers in bi-component fibers, adjusting parameters such as sheath-to-core ratio, fiber diameter, and polymer blend composition. By carefully controlling these parameters, the fabric achieves adequate softness through the softer polymer component while maintaining sufficient degradability through the PLA component, resolving the contradiction between softness and degradability.
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 solution provides a biodegradable nonwoven fabric with improved drapability and tensile strength, surprising given the typical mutual exclusion of these properties in thermobonded fabrics, while allowing for a high amount of biodegradable polylactic acid, thus enhancing the fabric's softness and mechanical stability.
Implementation Method 1
a nonwoven fabric comprising a plurality of polylactic acid-containing fibers that form a nonwoven web, wherein the web has a side which is provided with an alternating pattern of individualized bonded areas
Data Source
AI summary
A nonwoven fabric having polylactic acid-containing fibers forming a nonwoven web is provided. The web has a side having an alternating pattern of individualized bonded areas which bonded areas define rods arranged in the cross direction of the web. The rods are arranged so that in the machine direction of the web no uninterrupted regions exist along the web while in the cross direction the arrangement of rods defines uninterrupted regions that extend continuously along the web, the alternating pattern of individualized bonded areas defines a non-bonded area. The web has a basis weight from 5-50 g/m2, the surface of the bonded areas is from 5-20% of the total surface of the side, and the surface of the non-bonded area is from 80-95% of the total surface of the side. Processes for forming the nonwoven fabric and an absorbent article including the nonwoven fabric are also provided.