Surface Polyolefin Coating for Soft, Strong Low-Density Tissue
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Solution Overview
Problem
Existing methods for producing high-strength, soft, and absorbent tissue products face challenges as increasing one property often adversely affects others, such as softness and strength, especially when applying polymer dispersions to non-creped webs, which tend to penetrate and reduce mass efficiency, leading to stiff products.
Innovation Solution
A method involving a polyolefin dispersion with high viscosity, applied directly to a non-creped web, where the dispersion has a specific viscosity calculated by the equation y = 40e^0.07x, with particles of 0.1 to 3 µm diameter and 40-60% solids, preventing penetration and maintaining morphological structure for enhanced softness and strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If dispersion viscosity is increased to prevent penetration, then mass efficiency is improved, but application difficulty increases
Solution Approach 1:
The patent optimizes the viscosity parameter within a specific range achieved through 40-60% solids content and controlled particle size (0.1 to 3 µm). This viscosity is high enough to prevent penetration and improve mass efficiency, but not so high as to create excessive application difficulty, balancing both requirements.
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 effectively keeps the polyolefin dispersion on the web surface, preventing phase inversion and enhancing hand feel and softness while improving the web's strength and maintaining its morphological structure, resulting in a softer and stronger tissue product.
Implementation Method 1
the additive composition has a viscosity of equal or greater than a value calculated by an equation of y = 40 e 0.07x
Implementation Method 2
A relatively high viscosity POD is used so that the POD is diposed substantially on top of the web surface. The high viscosity also prevents phase inversion from occurring.
Implementation Method 3
the coating derived from POD has a morphological structure, which promotes hand feel and softness improvement
Data Source
Figure 1A~2B
Figure 1C~2C
Figure 1D~2D
AI summary
Sheet-like products, such as tissue products made from a low-density web, are disclosed containing an additive composition. The additive composition, for instance, comprises an aqueous dispersion containing an alpha-olefin polymer, and an ethylene-carboxylic acid copolymer. The additive composition may be applied to the surface of the web so that it does not thoroughly or even substantially penetrate the web. For instance, the additive may be applied to one or both surfaces of the web by gravure printing, press coating, spraying or the like. The additive composition may improve the strength of the tissue web and/or improve the perceived softness of the web.