High Viscosity Additive Application on Tissue Webs
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Solution Overview
Problem
Existing methods for applying polymer dispersions to low density tissue webs often result in penetration, increasing stiffness and requiring creping, which complicates the process and affects product properties like softness and strength.
Innovation Solution
A process using high viscosity compositions in conjunction with a micro-patterned compressible surface, such as a roll with raised elements, to apply additives to the surface of tissue webs at high speeds, maintaining the composition on the surface and controlling its distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If aqueous polymer dispersion is applied to low density tissue web, then softness is improved, but the composition penetrates the web increasing stiffness
Solution Approach 1:
The patent applies a high viscosity polymer dispersion (greater than 500 cps) instead of conventional low viscosity dispersions. This parameter change in viscosity prevents penetration into the low density tissue web while maintaining surface coating, thereby improving softness without increasing stiffness.
2Device complexity
If conventional polymer dispersion is applied without creping, then processing complexity is reduced, but composition penetration occurs affecting product properties
Solution Approach 1:
By changing the viscosity parameter of the polymer dispersion to greater than 500 cps, the patent enables application without creping operations. The high viscosity prevents penetration during application, eliminating the need for complex creping equipment while maintaining product properties.
3Productivity
If high processing speed is used for composition application, then productivity is improved, but composition distribution control becomes difficult
Solution Approach 1:
The patent uses high viscosity composition (greater than 500 cps) that maintains its integrity at high processing speeds. The high viscosity prevents splashing and ensures uniform distribution control even when the web moves rapidly through the application zone, enabling both high productivity and precise composition distribution.
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 allows for efficient application of additives at high processing speeds, minimizing fiber buildup and maintaining the softness and strength of the tissue web, while preventing penetration and phase inversion.
Implementation Method 1
The surface of the second roll may comprise a compressible material defining a pattern of raised elements. At least certain of the raised elements have a surface that has at least one dimension of less than about 500 microns.
Implementation Method 2
In accordance with the present disclosure, the additive composition contains a polymeric material and has a viscosity of at least 500 cps.
Data Source
AI summary
A process is disclosed for topically applying additive compositions to planar substrates, such as tissue webs. In one embodiment, the process is designed to apply relatively high viscous compositions to base sheets at high speeds in a manner that prevents the additive composition from penetrating into the sheet. The additive composition having the relatively high viscosity can be applied to the base sheet in one embodiment using an offset gravure printing process. The applicator roll includes a pattern of raised elements. The raised elements define a surface having at least one dimension that is less than 500 microns. The raised elements are also spaced closely together in order to prevent fiber buildup on the roll during relatively fast processing speeds.