Soft through air dried tissue
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Solution Overview
Problem
Conventional tissue-making processes using wet end additives require large amounts, leading to increased costs and reduced tissue strength, and through air drying results in a flattened surface profile that hinders cleaning ability and softener effectiveness.
Innovation Solution
A multi-layer through air dried tissue structure with a first exterior layer of hardwood fibers, an interior layer of softwood fibers, and a second exterior layer of hardwood fibers, incorporating ionic and non-ionic surfactants as wet end additives, along with dry and wet strength additives, to maintain softness and cleaning effectiveness without excessive additive use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wet end additives are used in the pulp mixture to achieve desired tissue attributes, then the tissue acquires the desired chemical state, but a large amount of additive is required which increases cost and reduces tissue strength
Solution Approach 1:
The tissue is divided into multiple layers with different functions: exterior layers provide strength and absorbency, while the interior layer contains the wet end additives for softness and cleaning. This segmentation allows additives to be concentrated where needed rather than distributed throughout the entire tissue structure, reducing the total amount of additive required while maintaining tissue strength in the exterior layers.
Solution Approach 2:
The interior layer is specifically designed with different properties than the exterior layers - it contains the wet end additives (ionic and non-ionic surfactants) that provide softness and cleaning ability. This local concentration of additives in the interior layer achieves the desired chemical state where needed without compromising the structural integrity and strength of the exterior layers.
2Reliability
If topical softeners are added after web formation to avoid wet end additive drawbacks, then additive usage is reduced, but the tissue develops a flattened surface profile that hinders cleaning ability and limits softener effectiveness
Solution Approach 1:
The wet end additives are incorporated into the interior layer during the web formation process, before the tissue is dried and finished. This preliminary incorporation of softeners and surfactants into the tissue structure during formation allows the tissue to maintain its natural surface profile and cleaning ability, while still achieving the desired softness and chemical state in the finished product.
3Productivity
If through air drying is used to dry the tissue web, then drying efficiency is improved, but the tissue develops a flattened surface profile
Solution Approach 1:
The interior layer is specifically designed with different properties than the exterior layers - it contains the wet end additives (ionic and non-ionic surfactants) that provide softness and cleaning. This local concentration of additives in the interior layer achieves the desired chemical state where needed without compromising the structural integrity and strength of the exterior layers.
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 achieves improved softness, tensile strength, and surface uniformity while reducing the need for large amounts of additives, maintaining tissue strength and enhancing cleaning ability.
Implementation Method 1
The interior layer includes a first wet end additive comprising an ionic surfactant and a second wet end additive comprising a non-ionic surfactant
Implementation Method 2
The web is then dried by transferring the web to a forming surface and then directing a flow of heated air onto the web
Implementation Method 3
A multi-layer through air dried tissue according to an exemplary embodiment of the present invention comprises a first exterior layer, an interior layer and a second exterior layer
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
A multi-layer structured tissue having improved surface roughness characteristics comprises an outer surface having an Average Peak to Valley Waviness of 140 microns or less.