Non-crosslinked Latex Creping for Low Stiffness Tissue
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Solution Overview
Problem
Existing tissue manufacturing processes face challenges in balancing the competing properties of bulk, hand-feel, and absorbency while maintaining product strength and dispersibility, often compromising on softness and stiffness.
Innovation Solution
The use of a creping process with a non-crosslinked latex polymer on tissue plies, which improves surface properties like smoothness and durability without negatively affecting stiffness, and the absence of permanent wet strength agents ensures the product is readily dispersible.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If fiber bonding is reduced to increase softness, then softness is improved, but strength deteriorates
Solution Approach 1:
A binder composition is introduced as an intermediary substance between the fibrous web layers. This binder comprises a polymer emulsion and a crosslinking agent that forms crosslinked structures to strengthen the web without requiring extensive fiber bonding, thus maintaining softness while improving strength.
Solution Approach 2:
The invention creates a composite structure by combining the fibrous web with a crosslinked binder system. The binder composition includes polymer emulsion particles that crosslink to form a reinforcing network within the tissue product, creating a composite material that exhibits both softness and enhanced strength.
2Strength
If crosslinked latex binder is used to improve strength, then strength is improved, but dispersibility deteriorates
Solution Approach 1:
The invention carefully controls the crosslinking parameters by using a specific crosslinking agent concentration and type in the binder composition. This parameter optimization allows the binder to provide sufficient crosslinked structures for strength while minimizing excessive crosslinking that would prevent dispersibility, achieving a balance between these competing requirements.
3Shape
If multiple creping steps are used to improve surface properties, then surface smoothness is improved, but manufacturing complexity increases
Solution Approach 1:
The invention merges the binder application and creping operations into a single integrated step. The binder composition is applied to the fibrous web and then creped in one continuous operation, eliminating the need for separate binder application and creping steps, thus reducing manufacturing complexity while maintaining surface quality.
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 low stiffness, low surface lint, and high strength, with a Stiffness Index less than 5.0 and Slough less than 5.0 mg, making them suitable for applications like bath tissue with improved dispersibility.
Implementation Method 1
a non-crosslinked latex polymer disposed on an outer surface of the tissue ply
Implementation Method 2
at least one of the plies has been prepared by a creping process
Data Source
AI summary
Disclosed are non-treated, creped tissue webs, and tissue products produced therefrom, having low stiffness and surface lint. The inventive products may be produced by a print creping process adapted to dispose a non-crosslinked latex polymer on at least one of the outer surfaces of the tissue product. The non-crosslinked latex polymer creping composition does not negatively affect stiffness such that the products generally have a Stiffness Index less than about 5.0, such as from about 2.5 to about 5.0.