Fabric Creping and Drawing for Bulk Absorbent Sheet Transfer
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Solution Overview
Problem
Conventional papermaking processes face challenges in effectively transferring high-consistency webs to dryers and achieving energy-efficient production of soft, bulky tissue products, particularly due to difficulties in web transfer and high energy consumption in thermal dewatering.
Innovation Solution
A method involving fabric creping and drawing of a cellulosic sheet, where the web is compactively dewatered, creped onto a creping fabric, and then drawn to expand, utilizing a resinous adhesive coating for secure transfer and preservation of a drawable reticulum structure, allowing for increased void volume and bulk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If through-air drying processes are used to produce soft, bulky tissue products, then product quality (bulk and softness) is improved, but energy consumption increases
Solution Approach 1:
The drying process is segmented into multiple zones with different air velocities and temperatures. The web is dried in stages, with initial rapid drying followed by slower finishing drying, allowing bulk formation while reducing total energy consumption compared to conventional single-stage high-temperature drying
Solution Approach 2:
Different regions of the web receive different drying conditions - the surface layers are dried more rapidly while the interior maintains higher moisture content longer, creating a gradient structure that preserves bulk while achieving surface dryness. This localized control of drying intensity reduces overall energy requirements
2Use of energy by moving object
If mechanical dewatering (wet pressing) is used instead of thermal dewatering, then energy consumption is reduced, but production of soft, bulky products is compromised
Solution Approach 1:
The invention combines mechanical dewatering (wet pressing) with subsequent through-air drying in a hybrid process. The mechanical pressing removes excess water efficiently at low energy cost, preparing the web for the drying stage where bulk is formed, thus merging the advantages of both methods
Solution Approach 2:
Mechanical dewatering is performed as a preliminary action before thermal drying. By removing a significant portion of water mechanically first, the subsequent drying process operates on a less saturated web, reducing the energy required for drying while still achieving the desired bulk and softness
3Productivity
If high-consistency web transfer to dryer is attempted, then production speed is improved, but transfer difficulty increases
Solution Approach 1:
A transfer fabric or intermediate carrier is used to facilitate web transfer from the forming section to the dryer. This intermediary element provides a stable surface for handling high-consistency webs, enabling reliable transfer at higher production speeds without direct contact between the web and dryer surface
Solution Approach 2:
The web is pre-conditioned in the forming section to achieve optimal consistency and stability before transfer. This preliminary preparation ensures the web has sufficient strength and uniformity to be transferred at high speed without breaking or deforming, even at elevated consistencies
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 fabric-creped absorbent sheet with unique macroscopic properties, including increased bulk and absorbency, while reducing energy consumption and improving production efficiency.
Implementation Method 1
utilizing a resinous adhesive coating for secure transfer
Implementation Method 2
drying the web on the drying cylinder
Implementation Method 3
drawn between a first draw roll and a second draw roll to expand the dried web
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A method of making a fabric-creped absorbent cellulosic sheet comprising: a) compactively dewatering a papermaking furnish to form a nascent web having an apparently random distribution of papermaking fiber; b) applying the dewatered web having the apparently random fiber distribution to a translating transfer surface moving at a first speed; c) 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 a fabric creping nip defined between the transfer surface and the creping fabric wherein the fabric is traveling at a second speed slower than the speed of said transfer surface, the fabric pattern, nip parameters, velocity delta and web consistency being selected such that the web is creped from the transfer surface and redistributed on the creping fabric to form a web with a drawable reticulum.