Non-Crosslinked Latex Binder for Durable and Dispersible Creped Tissue
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Solution Overview
Problem
There is a need for single-use tissue products that balance dry durability with rapid breakup in aqueous environments to ensure flushability without compromising on dry strength or increasing Slosh time.
Innovation Solution
Creped tissue webs with multiple plies, where at least one surface is treated with a non-crosslinked latex binder, providing high dispersibility and wet strength while maintaining low Slosh time, achieved through a creping and print creping process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If water soluble fibers or water sensitive binders are used to improve dispersibility, then rapid breakup when wetted is achieved, but dry durability deteriorates
Solution Approach 1:
The patent changes the chemical parameter of the binder from water-sensitive (starch, polyvinyl alcohol) to non-crosslinked latex, which provides different binding characteristics. The latex binder maintains bond strength in dry state for durability while allowing rapid separation when wetted, resolving the contradiction between dry durability and wet dispersibility
Solution Approach 2:
The patent uses a composite fibrous structure combining wood pulp fibers with non-crosslinked latex binder. This composite material leverages the strength-providing capability of latex in dry state while maintaining the rapid breakup property when wetted, achieving both dry durability and wet dispersibility simultaneously
2Reliability
If ion trigger binders are used to provide rapid disintegration upon dilution, then dispersibility is improved, but dry strength deteriorates
Solution Approach 1:
The patent changes the trigger mechanism parameter from ion-triggered disintegration to moisture-induced separation with non-crosslinked latex. This parameter change allows the binder to maintain strong bonding in dry state while enabling rapid separation when exposed to water, achieving both dry strength and rapid disintegration without relying on ion triggers
3Strength
If wet tensile strength is increased to improve durability, then dry durability is improved, but dispersability deteriorates and Slosh time increases
Solution Approach 1:
The patent changes the binder chemistry parameter to non-crosslinked latex, which provides wet tensile strength through physical adhesion rather than chemical crosslinking. This allows the tissue to maintain high wet strength for durability while the physical bonds break down rapidly in water, preserving dispersibility and keeping Slosh time low
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 creped tissue products exhibit improved durability, flexibility, and dispersibility, with Slosh times less than 2 minutes and high cross-machine direction wet tensile strength, maintaining a high degree of wet strength and good dispersability.
Implementation Method 1
a non-crosslinked binder disposed on the first or the second surface
Data Source
AI summary
The multi-ply tissue products that are both durable and dispersible may be manufactured using a creping process that employs a non-crosslinked vinyl acetate-ethylene polymer as a creping agent. The products generally have a Slosh time less than 2 minutes, such as less than about 60 seconds, such as less than about 45 seconds. Surprisingly, the foregoing Slosh times are achieved despite the tissue products having relatively high cross-machine direction (CD) wet tensile strength, such as greater than about 100 g/3″. Typically, increasing wet tensile strength, particularly wet CD tensile strength, negatively effects dispersability and increases Slosh time. Despite this trend, the multi-ply tissue products have a relatively high degree of wet strength and good dispersability.