Continuous Fiber Web Deposition with Fluid Diversion for Loft
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Solution Overview
Problem
Conventional spunbond processes result in reduced loft, reduced softness, and reduced fiber crimping of continuous fiber nonwoven webs due to compaction and surface sealing, which is undesirable for applications like soft nonwovens in absorbent articles.
Innovation Solution
The method involves removing process fluid from a first location on the moving porous member, using a fluid handling roll and an elongated fluid diversion element to prevent fiber compaction, and applying pre-bonds with hot fluid or steam to allow fibers to crimp and maintain loft, while minimizing machine direction strain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If vacuum is applied under the moving porous member to remove fluid, then fluid removal is improved, but loft of continuous fiber strands is reduced
Solution Approach 1:
The moving porous member is divided into a first portion and a second portion along the machine direction. The first portion has a first vacuum level for initial fluid removal and fiber deposition, while the second portion has a second vacuum level that is less than the first vacuum level to allow fiber lofting and crimping. This segmentation of the vacuum application zones resolves the contradiction by spatially separating fluid removal from loft preservation.
2Stability of the object's composition
If compaction roller is used to compact the web, then web stability is improved, but loft is reduced
Solution Approach 1:
The patent removes the compaction roller from the conventional spunbond process. Instead of applying mechanical compaction to stabilize the web, the invention relies on controlled vacuum levels and fiber interentanglement during the deposition process to achieve web stability without loft reduction. This extraction of the compaction element directly resolves the contradiction between stability and loft.
3Strength
If hot air knife is used to pre-bond the web, then bonding is improved, but air permeability is reduced
Solution Approach 1:
The patent applies bonding in a localized and controlled manner through the vacuum differential between the first and second portions of the moving porous member. The first portion provides initial fiber deposition with higher vacuum for stability, while the second portion provides gentler vacuum to allow fiber crimping and maintain air permeability. This localized quality differentiation resolves the contradiction between bonding strength and air permeability.
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 approach enhances the loft and softness of nonwoven webs by allowing fibers to crimp and entangle, reducing fiber blow-back, and maintaining web integrity during processing.
Implementation Method 1
vacuum may be applied under the moving porous member to aid in drawing the continuous fiber strands and the fluid toward the moving porous member
Implementation Method 2
The fluid (i.e., process air) flows toward the moving porous member
Implementation Method 3
applying pre-bonds with hot fluid or steam to allow fibers to crimp and maintain loft
Data Source
AI summary
A method of creating a soft and lofty continuous fiber nonwoven web is provided. The method includes providing molten polymer to a spinneret defining a plurality of orifices, and flowing a fluid intermediate the spinneret and a moving porous member. The moving porous member is positioned below the spinneret. The method includes using the fluid to draw or push the molten polymer, in a direction that is toward the moving porous member, through at least some of the plurality of orifices to form a plurality of individual continuous fiber strands. The method includes depositing the continuous fiber strands on the moving porous member at a first location to create an intermediate continuous fiber nonwoven web, and removing and/or diverting some of the fluid proximate to the first location to maintain loft and softness in the deposited intermediate continuous fiber nonwoven web.