Patterned Cylinder Cylinder Creping Bulk Absorbency Trade-off
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Solution Overview
Problem
Conventional papermaking methods either result in paper products with low absorbency and high fiber cost due to excessive compaction or high drying costs and weak fiber binding due to minimal compaction, while belt creping methods are cumbersome and costly with limited pattern options and production speed constraints.
Innovation Solution
A papermaking process utilizing a patterned cylinder to mold and reorient paper fibers, allowing for variable fiber orientations and bulk enhancement without the limitations of belt creping, by transferring the nascent web onto a patterned surface for cylinder creping and molding, followed by controlled dewatering and drying.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional wet pressing with high compaction is used, then production speed and runability are improved, but bulk and absorbency deteriorate
Solution Approach 1:
The press roll surface is provided with a patterned structure comprising a plurality of cells that define recesses and protrusions. This creates local variations in compaction pressure across the paper web, with some areas experiencing higher compression and others experiencing lower compression or even expansion, thereby maintaining bulk in certain regions while still achieving effective dewatering overall.
2Quantity of substance
If conventional wet pressing with high compaction is used, then fiber cost efficiency is improved, but absorbency deteriorates
Solution Approach 1:
The patterned press roll creates zones of differential compaction where some areas maintain higher bulk and porosity, preserving absorbency while other areas achieve sufficient dewatering for production efficiency.
Solution Approach 2:
The patterned structure on the press roll surface creates a porous configuration in the resulting paper product by preventing complete consolidation of fibers. The recesses and protrusions leave void spaces that maintain capillary action and liquid absorption capabilities.
3Volume of stationary object
If minimal compaction is used, then bulk and softness are improved, but drying costs increase
Solution Approach 1:
The patterned press roll applies compaction selectively rather than uniformly across the entire web. This localized compaction approach achieves adequate dewatering in critical areas while preserving bulk in other areas, reducing the overall water content that requires thermal drying and thereby lowering energy costs.
4Strength
If minimal compaction is used, then fiber binding strength deteriorates, but drying costs increase
Solution Approach 1:
The patterned press roll structure creates localized zones of higher compaction pressure that provide sufficient fiber-to-fiber contact and bonding strength in critical areas, while other zones maintain lower pressure to preserve bulk and reduce drying energy requirements.
5Adaptability or versatility
If belt creping is used, then pattern flexibility is limited, but device complexity increases
Solution Approach 1:
Instead of using a flexible belt with a pattern (as in conventional belt creping), this invention uses a rigid or semi-rigid press roll with the pattern formed on its surface. This inverted approach simplifies the device structure while maintaining or enhancing pattern flexibility through the ability to create various cell geometries and arrangements on the roll surface.
6Productivity
If belt creping is used, then production speed is constrained, but device complexity increases
Solution Approach 1:
The invention replaces the complex belt creping mechanism with a simpler patterned press roll integrated into the existing press section. This eliminates the need for separate belt drive systems and tensioning mechanisms, allowing the paper web to be processed at higher speeds without the mechanical constraints that limit belt creping operations.
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 method achieves paper products with improved bulk and absorbency while maintaining strength and reducing production costs, offering flexibility in pattern design and increased production efficiency compared to traditional methods.
Implementation Method 1
transferred the nascent web onto a patterned surface for cylinder creping and molding
Implementation Method 2
A molding nip is formed between the patterned cylinder and a Yankee drum, and a moist nascent web is molded by the patterned cylinder to form a molded web
Data Source
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AI summary
A method of making a fibrous sheet, the method comprising: (a) forming a nascent web from an aqueous solution of papermaking fibers; (b) applying the nascent web to an outer surface of a steam filled drum and dewatering the nascent web by moving the nascent web on the outer surface of the steam filled drum to form a dewatered web having a consistency from about thirty percent solids to about sixty percent solids; (c) transferring the dewatered web from the outer surface of the steam filled drum to a patterned surface of a patterned cylinder in a molding zone, the molding zone being a nip defined between the outer surface of the steam filled drum and the patterned surface of the patterned cylinder, the patterned surface (i) being formed on the exterior of the patterned cylinder and (ii) having at least one of a plurality of recesses and a plurality of protuberances, such that papermaking fibers of the dewatered web are (i) redistributed on the patterned surface and (ii) shaped by at least one of the plurality of recesses and the plurality of protuberances of the patterned surface in the molding zone to form a molded paper web; (d) transferring the molded paper web from the patterned surface of the patterned cylinder to a pickup surface; and (e) drying the molded paper web in a drying section to form a fibrous sheet.