Molding Roll Permeable Surface Papermaking Fiber Structure
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Solution Overview
Problem
Conventional papermaking methods face challenges in achieving high bulk and absorbency while maintaining strength and low drying costs, with existing methods like CWP resulting in low absorbency and rough texture, and TAD being costly and producing weak paper products.
Innovation Solution
A method using a molding roll with a permeable patterned surface to redistribute and draw papermaking fibers into recesses, enhancing bulk and absorbency without the inefficiencies of TAD and the complexity of belt creping systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If conventional wet pressing (CWP) is used to dewater the paper web, then drying costs are low and production speed is high, but the paper product has low bulk and low absorbency with rough texture
Solution Approach 1:
The molding roll applies preliminary action by redistributing and drawing fibers into recesses during the dewatering stage, creating a three-dimensional fiber structure before drying occurs. This preliminary structuring of the fiber network enables high bulk to be achieved without requiring expensive thermal drying processes, thus resolving the contradiction between low drying cost and high bulk
2Productivity
If conventional wet pressing (CWP) is used to dewater the paper web, then production speed is high, but the paper product has low absorbency and rough texture
Solution Approach 1:
The molding roll creates local quality variations by forming distinct fiber structures in different zones of the paper web. The recesses in the molding roll surface create localized three-dimensional fiber arrangements that enhance absorbency in specific areas, while maintaining overall high production speed through continuous web processing
3Shape
If through-air-drying (TAD) is used to produce high bulk paper products, then bulk is high, but drying costs are high and fiber strength is low
Solution Approach 1:
The molding roll performs preliminary structuring of the fiber network by redistributing fibers and drawing them into recesses during the dewatering phase. This creates a three-dimensional fiber architecture that achieves high bulk without requiring the expensive thermal drying energy input of TAD processes, thus resolving the contradiction between high bulk and low drying cost
4Shape
If through-air-drying (TAD) is used to produce high bulk paper products, then bulk is high, but fiber strength is low
Solution Approach 1:
The molding roll changes the physical parameters of fiber arrangement by redistributing fibers and drawing them into recesses at controlled consistency levels (10-70% solids). This creates optimal fiber-to-fiber contact and bonding geometry that enhances fiber strength while maintaining high bulk, resolving the contradiction between these two properties
5Shape
If a molding roll with permeable patterned surface is used to redistribute and draw fibers into recesses, then bulk and absorbency are improved, but device complexity increases
Solution Approach 1:
The molding roll performs multiple functions simultaneously: it acts as a dewatering surface, a fiber redistributing mechanism, a structuring tool that draws fibers into recesses, and a molding element. By combining these functions into a single component, the device achieves high bulk and improved absorbency without proportionally increasing overall system complexity
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 produces paper products with improved bulk and absorbency, reducing fiber cost and equipment complexity, while maintaining strength and operational efficiency.
Implementation Method 1
applying a vacuum at a molding zone defined between the transfer surface and a molding roll... The vacuum is applied in the interior of the molding roll to cause air to flow through the permeable patterned surface into the interior of the molding roll
Implementation Method 2
The vacuum is applied during the transferring of the dewatered web from the transfer surface to the permeable patterned surface of the molding roll... and the papermaking fibers of the dewatered web are (i) redistributed on the permeable patterned surface and (ii) drawn into the plurality of recess of the permeable patterned surface
Data Source
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AI summary
A method of making a fibrous sheet. The method includes forming a nascent web from an aqueous solution of papermaking fibers, moving a dewatered web on a transfer surface, and applying a vacuum at a molding zone defined between the transfer surface and a molding roll. The molding roll includes a permeable patterned surface on an exterior of the molding roll. The method also includes transferring the dewatered web from the transfer surface to the permeable patterned surface at the molding zone. The vacuum is applied during the transferring of the dewatered web, and the papermaking fibers of the dewatered web are (i) redistributed on the permeable patterned surface and (ii) drawn into a plurality of recess of the permeable patterned surface, in order to form a molded paper web. The method further includes drying the molded paper web in a drying section to form a fibrous sheet.