Extensible Back Ear Laminates for Low-Force, Skin-Friendly Fit
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Solution Overview
Problem
Existing absorbent articles with high modulus back ears require high force for extension, leading to poor fit and potential skin irritation due to non-uniform surfaces and large gathers, while low modulus strands provide insufficient stretch and uneven surfaces, affecting user comfort and holistic perception.
Innovation Solution
The absorbent article features back ears with an engineering strain greater than 8% at 2N of force and a surface roughness below 300 μm, achieved through a laminate structure of nonwoven layers and elastomeric materials, ensuring even extension and reduced skin marking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high modulus back ears are used to maximize sustained fit and minimize leakage, then fit reliability is improved, but the force required for extension increases making application difficult
Solution Approach 1:
The patent changes the mechanical parameter of the back ear material from high modulus to low modulus stretch, transforming the force-extension characteristics to require less force while maintaining adequate fit reliability through the laminate structure and elastic recovery properties
2Ease of operation
If low modulus elastic strands are used to reduce extension force, then ease of operation is improved, but the surface becomes non-uniform causing skin irritation
Solution Approach 1:
The patent employs a composite laminate structure combining nonwoven fabric layers with elastic material layers, where the nonwoven layers provide a uniform skin-contact surface while the elastic layers provide the necessary stretch, thus eliminating skin irritation while maintaining ease of operation
Solution Approach 2:
The patent applies different material properties to different layers of the back ear: the skin-contacting nonwoven layers are designed for uniformity and softness, while the internal elastic layers are designed for stretch and recovery, allowing each layer to perform its specific function optimally
3Ease of manufacture
If elastic material is bonded to nonwoven layers at zero relative strain, then manufacturing simplicity is maintained, but the surface uniformity and skin comfort are compromised
Solution Approach 1:
The patent applies preliminary stretching to the elastic material layers before bonding them to the nonwoven layers, which pre-establishes the desired surface uniformity and reduces gathers, while the bonding process itself remains relatively simple and integrated into the manufacturing flow
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 comfortable, snug fit with minimal force requirement and reduces skin irritation by maintaining a uniform surface, enhancing user experience and product perception.
Implementation Method 1
back ears having low roughness for being soft and gentle to the skin are preferred... each back ear having a fastener located at or near the outboard edge thereof... adapted to attach or adhere to a fastener receiving zone
Implementation Method 2
Elastic laminates may be produced by joining one or more nonwoven layers and an elastic material at approximately zero relative strain where the nonwoven layer(s) and the elastic material may be bonded using adhesive
Data Source
AI summary
An absorbent article has a liquid pervious topsheet, a liquid impervious backsheet, an absorbent core disposed between the topsheet and backsheet; first and second opposing longitudinal side edges, a front waist region and a back waist region; and a first and second back ear extending outwardly from the first and longitudinal side edges in the back waist region, respectively. The first and second back ears have a back ear width (W) and include a laminate having an elastomeric material sandwiched between a first nonwoven layer and a second nonwoven layer, wherein the elastomeric material has an elastic material width (Y), and wherein elastic material width (Y) is less than back ear width (W). The first back ear and the second back ear exhibit between about 1% to about 20% of a 4 hour growth when measured according to the 4 hr. Growth Test described herein.