Fabric-Creped Cellulosic Sheet Structure for High-Bulk Low-Energy Tissue
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Solution Overview
Problem
Conventional papermaking processes face challenges in effectively transferring high or intermediate consistency webs to dryers during fabric creping, leading to difficulties in producing products with enhanced bulk and softness while maintaining energy efficiency and using recycle fibers.
Innovation Solution
A method involving compactive dewatering followed by fabric creping, where the web is transferred to a patterned creping fabric at a consistency of 30-60% under pressure, with controlled velocity delta and nip parameters to create a drawable reticulum with fiber-enriched regions and lower basis weight linking regions, allowing for increased void volume and bulk upon drawing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If through-air drying is used to produce soft, bulky tissue products, then bulk and softness are improved, but energy consumption increases significantly
Solution Approach 1:
The patent changes the physical state and parameters of the web by controlling dewatering at specific consistencies (30-60%) and applying fabric creping with controlled velocity delta and nip parameters, transforming the web structure to create bulk without requiring energy-intensive through-drying
Solution Approach 2:
The patent segments the web into fiber-enriched regions and lower basis weight linking regions through fabric creping, creating a reticulum structure that provides bulk while reducing overall material density and energy requirements
2Use of energy by moving object
If wet pressing is used for mechanical water removal, then energy cost is reduced, but production of high-bulk products becomes difficult
Solution Approach 1:
The patent modifies the consistency parameter during processing, maintaining the web at 30-60% consistency during fabric creping rather than complete dewatering, which preserves the capacity for bulk development while keeping energy costs low through mechanical pressing
Solution Approach 2:
The patent introduces dynamic velocity delta between the transfer surface and creping fabric, creating a controlled creping action that develops bulk structure during the wet pressing process itself, eliminating the need for subsequent energy-intensive drying
3Manufacturing precision
If fabric creping is applied to high consistency webs, then product properties are influenced, but effective transfer to dryer becomes difficult
Solution Approach 1:
The patent optimizes the consistency parameter to a specific range (30-60%) that balances web stiffness for property development with sufficient flexibility for easy transfer to the dryer, avoiding both too-high and too-low consistency extremes
4Quantity of substance
If recycle furnish is used to reduce material cost, then web permeability decreases, but fabric creping effectiveness is reduced
Solution Approach 1:
The patent adjusts processing parameters including velocity delta and nip pressure to compensate for reduced permeability in recycle fiber webs, ensuring effective fabric creping and reticulum development even with lower permeability materials
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 method results in a fabric-creped absorbent cellulosic sheet with unique macroscopic properties, including increased bulk and reduced sidedness, by rearranging fibers to create a cohesive matrix that expands when drawn, effectively addressing the challenges of energy efficiency and fiber usage.
Implementation Method 1
the creping step occurring under pressure in the fabric-creping nip defined between the transfer surface and the creping fabric
Implementation Method 2
a differential velocity transfer during a pressing event serves to improve the molding and imprinting of a web with a deflection member
Implementation Method 3
The drawable reticulum of the web is characterized in that it comprises a cohesive fiber matrix capable of increasing its void volume upon dry-drawing
Data Source
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AI summary
Method of making a fabric-creped absorbent cellulosic sheet, the method comprising: (a) applying a jet of papermaking furnish to a forming wire, the difference between a jet velocity and a forming wire velocity being referred to as the jet/wire velocity delta; (b) compactively dewatering the papermaking furnish to form a nascent web; (c) applying the nascent web to a transfer surface; (d) fabric-creping the nascent web from the transfer surface such that the nascent web is redistributed on a creping fabric to form a creped web with a reticulum having a plurality of interconnected regions of different local basis weights, including at least (i) a plurality of fiber enriched regions having a high local basis weight, interconnected by way of (ii) a plurality of lower local basis weight linking regions; (e) drying the creped web; and (f) controlling the jet/wire velocity delta and the fabric-creping step, such that the dry machine direction to cross-machine direction (MD/CD) tensile ratio of the dried web is about at most 1.5.