Fabric-Creped Cellulosic Sheet with Drawable Reticulum Bulk
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Solution Overview
Problem
Fabric creping processes face difficulties in effectively transferring high or intermediate consistency paper webs to dryers, leading to energy-intensive thermal dewatering and limitations in using recycle fibers due to the need for permeable webs, which increases production costs and reduces the bulk and softness of tissue products.
Innovation Solution
A method of making a fabric-creped absorbent cellulosic sheet involving compactive dewatering, applying the web to a translating transfer surface, and fabric-creping under pressure with a patterned creping fabric, where the web is redistributed to form a drawable reticulum with fiber-enriched regions and lower basis weight linking regions, allowing for increased void volume and bulk when drawn.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If through-air drying is used to dry the web, then bulk and softness are improved, but energy consumption increases significantly
Solution Approach 1:
The web is compactively dewatered before drying to remove a significant portion of water mechanically. This preliminary dewatering action reduces the water content that would otherwise require energy-intensive thermal evaporation, while the compactive dewatering also creates a denser web structure that maintains bulk and softness properties.
Solution Approach 2:
The patent replaces thermal drying (through-air drying) with mechanical dewatering (compactive dewatering) as the primary water removal mechanism. This substitution uses mechanical pressure instead of thermal energy to remove water, significantly reducing energy consumption while achieving the desired web properties.
2Productivity
If fabric creping is used to transfer the web, then production speed increases, but effective transfer of high consistency web becomes difficult
Solution Approach 1:
The web undergoes compactive dewatering before being transferred to the fabric for creping. This preliminary dewatering action reduces the web consistency to an optimal level that facilitates easy transfer to the fabric, eliminating the transfer difficulties associated with high consistency webs while maintaining high production speeds.
3Adaptability or versatility
If permeable web structure is used to enable recycle fiber incorporation, then manufacturing flexibility improves, but bulk and softness decrease
Solution Approach 1:
The compactive dewatering process changes the physical parameters of the web, including density, porosity, and fiber arrangement. These parameter changes create a web structure that can accommodate recycle fibers effectively while maintaining or even enhancing bulk and softness properties, contrary to conventional approaches where permeability was sacrificed for fiber flexibility.
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 process results in a product with enhanced bulk and absorbency, tolerant to recycle fibers, and reduces energy consumption by mechanical dewatering, while maintaining the cohesive fiber matrix and preserving the drawable reticulum during drying and drawing.
Implementation Method 1
fabric-creping the web from the transfer surface at a consistency of from about 30 to about 60 percent utilizing a patterned creping fabric, the creping step occurring under pressure in the fabric-creping nip defined between the transfer surface and the creping fabric
Implementation Method 2
The fabric pattern, nip parameters, velocity delta and web consistency are selected such that the web is creped from the transfer surface and redistributed on the creping fabric
Implementation Method 3
applying the dewatered web having the apparently random distribution to a translating transfer surface moving at a first speed; and fabric-creping the web from the transfer surface... utilizing a patterned creping fabric... wherein the fabric is traveling at a second speed slower than the speed of said transfer surface
Implementation Method 4
The drawable reticulum of the web is characterized in that it comprises a cohesive fiber matrix capable of increasing in void volume when drawn and subsequently drawn
Data Source
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AI summary
The invention relates to a method of making a fabric-creped absorbent cellulosic sheet, the method comprising compactively dewatering a papermaking furnish to form a nascent web having an apparently random distribution of papermaking fiber; applying the nascent web having the apparently random fiber distribution to a translating transfer surface that is moving at a transfer surface speed; fabric-creping the nascent web from the transfer surface at a consistency of from about 30 to about 60 percent utilizing a creping fabric that is traveling at a fabric-creping speed, the fabric-creping speed being slower than the transfer surface speed, the fabric-creping step occurring under pressure in a fabric creping nip defined between the transfer surface and the creping fabric, the fabric pattern, nip parameters, velocity delta, and web consistency being selected such that the nascent web is creped from the transfer surface and redistributed on the creping fabric to form a creped web with a drawable reticulum having a plurality of interconnected regions of different local basis weights including at least (i) a plurality of fiber enriched regions of high local basis weight, interconnected by way of (ii) a plurality of lower local basis weight linking regions; and applying a vacuum to the web to increase the stretch of the web in the cross machine direction (CD) by at least about 5 percent with respect to a like web produced by a similar method, but without having a vacuum applied thereto after fabric-creping.