3D Hot-Melt Laminate for Soft Touch Absorbent Articles
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Solution Overview
Problem
Existing absorbent articles face challenges in achieving a soft touch while effectively managing body exudates, particularly with natural fibers that do not behave like synthetic fibers, requiring new developments to ensure performance.
Innovation Solution
A three-dimensional laminate is introduced, comprising a first layer intermittently bonded to a second layer by a hot-melt adhesive. The first layer features a plurality of protrusions not bonded to the second layer, and the hot-melt adhesive consists of more than 90% by weight of a heterophase polymer with an enthalpy of fusion of at least 10 J/g, which is free of tackifiers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a three-dimensional laminate structure is used to provide soft touch, then comfort is improved, but delamination risk increases
Solution Approach 1:
The adhesive is applied in a patterned manner rather than uniformly, creating regions of bonding and regions of non-bonding. This allows the first layer to have protrusions in some areas (providing soft touch comfort) while being firmly bonded in other areas (preventing delamination). The selective local bonding resolves the contradiction between comfort and stability.
Solution Approach 2:
The bonding interface is segmented into bonded regions and non-bonded regions. The adhesive is applied only in specific patterns (e.g., dots, lines, or isolated areas) rather than covering the entire surface. This segmentation allows the laminate to maintain both three-dimensional protrusions for comfort and sufficient bonding areas for delamination resistance.
2Ease of operation
If natural fibers are used in the first layer, then softness is improved, but bonding reliability deteriorates
Solution Approach 1:
The adhesive application is localized to specific regions where bonding is needed, while leaving other regions with natural fibers exposed to provide softness. This selective bonding approach allows natural fibers to maintain their softness-contributing properties while still achieving adequate bonding reliability in the adhesive regions.
Solution Approach 2:
The adhesive formulation parameters are specifically adjusted to work with natural fibers. The heterophase polymer composition and enthalpy of fusion are optimized to provide appropriate bonding strength for natural fiber materials, resolving the contradiction between maintaining natural fiber softness and achieving reliable bonding.
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 soft touch on the external surface of the absorbent article while maintaining the integrity of the three-dimensional structure, reducing the risk of delamination and improving fluid handling properties.
Implementation Method 1
The first layer is intermittently bonded to the second layer by a hot-melt adhesive
Implementation Method 2
The hot-melt adhesive comprises more than 90% by weight of a heterophase polymer having an enthalpy of fusion of at least 10 J/g
Implementation Method 3
having an enthalpy of fusion of at least 10 J/g, as measured according to the Enthalpy of Fusion Measurement Method described herein
Data Source
AI summary
An absorbent article such as a baby diaper comprising a three-dimensional laminate 30 having a first layer 1 intermittently bonded to a second layer 2 by a heterophase polymer. The topsheet comprises three-dimensional protrusions 9 in the first layer 1 which are not bonded to the second layer 2. The heterophase polymer has an enthalpy of fusion of at least 10 J/g. The laminate may be used on the wearer-facing side of the article as topsheet 24 and/or on the garment-facing side as part of the backsheet 26. The first layer may comprise natural fibers.