3D Tissue Web Structure for Bulk-Softness Calendering Trade-Off
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Solution Overview
Problem
The challenge lies in creating tissue products that are both soft and strong, while also being bulky and aesthetically pleasing, as existing methods like through-air drying often require trade-offs between these properties, such as compromising bulk for strength or aesthetics.
Innovation Solution
Improving the z-directional properties of tissue webs by non-compressively dewatering the nascent web using a structured papermaking fabric with elements of specific height, which enhances compression modulus and energy, resulting in a three-dimensional topography that maintains bulk and softness even under high calendering loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If through-air drying is used to increase sheet bulk, then bulk is improved, but strength is degraded
Solution Approach 1:
The invention changes the physical parameters of the tissue web by controlling the through-air drying process to achieve specific bulk and strength characteristics. By adjusting drying parameters and web formation conditions, the patent achieves a balance between increased bulk and maintained tensile strength that resolves the traditional trade-off between these properties.
2Ease of operation
If calendering is applied to improve softness, then softness is improved, but bulk is reduced
Solution Approach 1:
The invention performs preliminary actions during web formation and drying to pre-establish the desired bulk and softness characteristics before final calendering. By controlling the web structure during through-air drying and using structured fabrics, the patent reduces the need for aggressive calendering, thereby maintaining bulk while achieving softness.
3Ease of operation
If smooth surface is created for good handfeel, then handfeel is improved, but aesthetics are degraded
Solution Approach 1:
The invention applies local quality by using structured papermaking fabrics with varying element heights and configurations in different zones. This creates localized surface characteristics that provide good handfeel in contact areas while maintaining aesthetic topography in visible areas, resolving the contradiction between smoothness and visual appeal.
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 approach results in tissue products with improved compression energy, geometric mean tensile strength, and low stiffness, achieving high bulk and softness with enhanced processing capabilities and aesthetics, such as a TS7 value less than 10.5 and sheet bulk greater than 10 cc/g.
Implementation Method 1
non-compressively dewatering the nascent tissue web while supporting the web with a structured papermaking fabric
Implementation Method 2
non-compressively dewatering the nascent tissue web
Implementation Method 3
through-air dried tissue products
Data Source
AI summary
The present invention provides tissue webs and products having improved z-directional properties. The improved z-directional properties may be achieved by providing the structure with a unique three-dimensional surface topography, which increases the structure's Exponential Compression Modulus (K) and Caliper Under Load (C0). By improving both K and C0, the present inventors have also been able to provide tissue structures with relatively high Compression Energy (E), which enables the structures to be calendered at high loads without significant loss of sheet bulk or degradation of strength.