Dispersible Tissue Laminate Bonding
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Solution Overview
Problem
Existing flushable wet wipes often lack sufficient in-use strength and fail to adequately degrade in sewer or septic systems, particularly in non-turbulent water conditions, while also being cost-effective.
Innovation Solution
A dispersible tissue laminate comprising two adhesively bonded tissue plies with discrete bond points formed by a combination of adhesive, pressure, and temperature, using a triggerable binder that maintains strength during use but breaks down in disposal water, achieved by varying manufacturing processes such as applying adhesive to tissue plies supported by a topographical belt and passing them through a nip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If hydroentangling technology is used to make flushable wet wipes, then the wipes can be made with sufficient in-use strength, but they require substantial agitation to break apart and do not degrade adequately in relatively static environments
Solution Approach 1:
The wipe is segmented into multiple tissue plies (typically two plies) that are bonded together at discrete bond points rather than continuously. This segmentation allows the plies to separate easily during flushing while maintaining structural integrity during use. The discrete bond points create weak planes that facilitate breakdown in sewer systems.
Solution Approach 2:
The invention changes the bonding parameters from continuous high-strength bonding (hydroentangling) to discrete point bonding with controlled bond strength. The bond points are created with specific properties: small contact area, localized adhesive application, and controlled pressure/temperature conditions that create bonds strong enough for use but weak enough to break during flushing.
2Strength
If binder add-on is increased to improve in-use performance, then the wet wipe strength increases, but dispersibility suffers and cost increases
Solution Approach 1:
The adhesive is applied locally at discrete bond points rather than uniformly across the entire tissue surface. This localized application means adhesive is only present where needed to bond plies together, leaving most of the tissue surface free of adhesive coating. This maintains dispersibility while providing sufficient bonding strength at critical locations.
Solution Approach 2:
Instead of applying binder uniformly across the entire surface (excessive action), the invention applies adhesive partially only at discrete bond points. This partial action provides just enough bonding strength for in-use performance while avoiding excess adhesive that would hinder dispersibility and increase cost.
3Strength
If continuous adhesive bonding is used to join tissue plies, then in-use strength is improved, but the wipe fails to break apart adequately in wastewater systems
Solution Approach 1:
The continuous adhesive bond is segmented into discrete bond points. This segmentation creates unbonded regions between bond points that allow the plies to separate during flushing. The bond points are spaced sufficiently far apart to leave large unbonded areas that facilitate breakdown in wastewater systems.
Solution Approach 2:
The adhesive bonding is extracted from a continuous state and removed from most of the tissue surface, leaving only discrete bond points. This extraction of bonding function to specific locations eliminates the continuous adhesive barrier that would prevent dispersibility, while still providing necessary strength at critical bond locations.
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 provides wet wipes with a geometric mean wet tensile strength greater than 200 g/in and a Slosh Time of less than 60 minutes, ensuring effective breakdown in wastewater systems while maintaining handfeel and cost-effectiveness.
Implementation Method 1
a binder attaches to cellulose fibers, and bonds those fibers together in a network to deliver in-use strength
Implementation Method 2
They are relatively strong, such as having a geometric mean wet tensile strength (GMWT) greater than about 200 g/in
Implementation Method 3
The bond points may be formed by a combination of adhesive, pressure and/or temperature
Data Source
AI summary
Dispersible adhesively bonded wet tissue laminates comprising two or more adhesively bonded tissue plies. The first and second tissue plies may be adhesively bonded to one another discrete bond points by adhesive, such as a triggerable adhesive binder. The first and second tissue plies may differ in respect to at least one of basis weight, sheet bulk, tensile strength or fiber composition. The adhesively bonded wet tissue laminates are generally strong enough to withstand use, such as having a geometric mean wet tensile strength (GMWT) greater than about 200 g/in, but disperse quickly in water, such as having a Slosh Time less than about 60 minutes.