Structured Press Belt for High Bulk Tissue Paper
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Solution Overview
Problem
Current tissue papermaking techniques using the pressing method fail to achieve high bulk and softness comparable to Through Air Drying (TAD) methods while maintaining low energy consumption, as they result in lower bulk and energy-intensive processes.
Innovation Solution
A structuring belt with a three-dimensional patterned layer is used to dewater and structure the paper web, allowing for increased bulk and softness by embedding the fibrous network into cavities, which prevents compression and enhances the paper's absorption capacity, and is designed to achieve high dryness levels, reducing energy consumption by minimizing water evaporation in the drying stage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If conventional pressing techniques are used to dewater and structure the paper web, then the process is simple and energy-efficient, but the bulk and softness of the tissue paper are limited
Solution Approach 1:
The structuring belt applies local quality by having a specific three-dimensional patterned layer with cavities and protrusions that selectively embeds the fibrous network in certain areas while maintaining smoothness in others. This localized structural modification creates bulk and softness without requiring complex overall pressing mechanisms.
Solution Approach 2:
The invention transitions from conventional two-dimensional pressing surfaces to a three-dimensional patterned layer on the structuring belt. The cavities and protrusions in the third dimension create embossing effects that increase bulk and softness while the belt itself remains a relatively simple continuous structure.
2Shape
If Through Air Drying (TAD) methods are used to achieve high bulk and softness, then the paper quality is improved, but energy consumption increases significantly
Solution Approach 1:
The invention replaces the thermal field of Through Air Drying with a mechanical field. The three-dimensional patterned layer mechanically embeds the fibrous network into cavities, creating bulk and softness through physical deformation rather than thermal evaporation and drying, thus eliminating the high energy consumption associated with TAD.
Solution Approach 2:
The invention extracts the bulk and softness generation function from the drying process. By separating the structuring function into a dedicated mechanical pressing stage with the patterned belt, the subsequent drying stage requires much less energy since the bulk structure is already established before drying begins.
3Shape
If the structuring belt has a three-dimensional patterned layer with cavities, then the paper web achieves high bulk and softness, but the device complexity increases
Solution Approach 1:
The structuring belt is constructed as a composite structure combining a conventional belt body with a three-dimensional patterned layer. This layered composite allows the belt to provide both the mechanical function of a standard belt and the structural embossing function through the patterned cavities and protrusions, achieving softness without requiring an entirely complex device.
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 solution enables the production of tissue paper with bulk comparable to TAD methods (8-20 cm^3/g) while significantly reducing energy costs, achieving high dryness levels (40-50%) and improved absorption capacity and softness, thus overcoming the limitations of conventional pressing techniques.
Implementation Method 1
a structuring belt (14) running in an endless loop about a plurality of guide rolls (15), about a smooth transfer roll (16) located in connection to the drying section (4), and through the press nip (N1) of the main press (11) together with the formed fibrous web (1') in order to provide for dewatering and structuring of the formed fibrous web (1') when it passes through the press nip (N1)
Implementation Method 2
The press section (3) comprises a main press (11) including a first press element (12) and a second press element (13) which cooperate with each other to form a press nip (N1) between them
Data Source
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AI summary
A structuring layer (60) of a structuring belt (14) for structuring a wet fibrous web (1') in a press section (3) of a tissue papermaking machine for manufacturing high bulk tissue paper (1), said structuring layer having a web-carrying side with a surface (61) for cooperating with the fibrous web, said surface having depressions (63) forming a three-dimensional structure of the surface. According to the invention, the depressions are distributed over the web-carrying side and constitute altogether 20-80 % of the surface (61), said surface including a flat, continuous top surface area (70) between the depressions (63), said top surface area delimiting the depressions, and each depression has a dimension 1 of 0.25-2.5 mm in a first direction in the plane of the top surface area (70), a dimension b of 0.25-2.0 mm in a second direction in the plane of the top surface area (70), said directions being at right angles to each other, a mean depth d of 0.05-0.6 mm and an area a as measured in the plane of the top surface area (70) of 0.3-4.0 mm2. The invention also relates to a structuring belt with such a layer, a press section with such a structuring layer, a tissue papermaking machine with such a press section, a method of manufacturing a structured high bulk tissue paper web in such a tissue papermaking machine, and use of the said belt, as well as a tissue paper web produced in the machine.