Crosslinked Fiber Tissue Products for Bulk Without Strength Loss
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Solution Overview
Problem
Existing paper products face challenges in balancing bulk, strength, and softness, with conventional methods often leading to reduced strength or increased lint and slough due to fiber bonding disruptions.
Innovation Solution
Incorporating crosslinked softwood fibers with low kink and curl into tissue products, blended with conventional fibers, to form a layered tissue web structure that maintains strength while enhancing bulk and softness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of stationary object
If embossing is used to increase bulk, then bulk is improved, but strength is reduced and manufacturing complexity increases
Solution Approach 1:
The patent applies chemical parameter changes by introducing crosslinking agents (such as glyoxal, glutaraldehyde, or other dialdehydes) that react with cellulose hydroxyl groups to form crosslinks between fibers. This chemical modification changes the bonding parameters at the fiber level, enabling bulk enhancement through controlled fiber separation without the mechanical damage caused by embossing. The crosslinking density can be adjusted to optimize both bulk and strength properties.
Solution Approach 2:
The patent creates a composite fiber system by combining conventional papermaking fibers with crosslinked fibers in a controlled blend. The crosslinked fibers act as a distinct phase that provides bulk enhancement while maintaining strength, effectively creating a composite material system where each component contributes different properties. This composite approach allows the tissue product to achieve high bulk without the strength penalties associated with mechanical embossing.
2Ease of operation
If chemical debonding agents are used to increase softness, then softness is improved, but lint and slough increase
Solution Approach 1:
The patent fundamentally changes the mechanism of softness enhancement from chemical debonding to controlled physical crosslinking. Instead of using quaternary ammonium compounds that disrupt hydrogen bonds and create lint, the crosslinking agents form stable covalent bonds between fibers while maintaining fiber integrity. This parameter change in the bonding mechanism achieves softness through reduced fiber stiffness without generating harmful lint and slough byproducts.
Solution Approach 2:
The patent converts the potential harm of excessive fiber bonding (which causes stiffness) into a benefit by using controlled crosslinking. The crosslinks prevent unwanted fiber aggregation and maintain fiber flexibility while providing sufficient bonding for strength. This transforms the harmful effect of strong fiber-to-fiber bonding into a beneficial controlled structure that enhances softness without creating lint.
3Strength
If crosslinked fibers are used to maintain strength, then strength is improved, but bulk may be reduced
Solution Approach 1:
The patent applies local quality by distributing crosslinked fibers strategically within the tissue web structure rather than uniformly throughout. By controlling the spatial distribution and concentration of crosslinked fibers in specific zones, the patent achieves localized strength enhancement where needed while maintaining bulk in other regions. This local application allows optimization of both strength and bulk properties in different parts of the same tissue product.
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 resulting tissue products exhibit improved formation, bulk, and durability with reduced stiffness, maintaining strength and softness comparable to or better than products made entirely of conventional fibers.
Implementation Method 1
crosslinked softwood fibers... The crosslinked softwood fibers consist essentially of crosslinked southern softwood kraft fibers
Implementation Method 2
The long chain alkyl groups provide softness to the tissue sheet by disrupting fiber-to-fiber hydrogen bonds in the sheet
Data Source
Figure 1~2
AI summary
The present disclosure relates to tissue products comprising crosslinked fibers. The tissue products generally have good formation, such as a Formation Index greater than about 20, strength, such as geometric mean tensile strengths greater than about 700 g/3" and high bulk, such as sheet bulks greater than about 10 cc/g. Unlike many prior art crosslinked fibers, the crosslinked softwood pulps of the present invention, which are preferably prepared using a glyoxal based crosslinking reagent, are readily dispersible in water and have relatively low degrees of kink and curl. As such, the fibers are well suited for forming wet-laid tissue products and more particularly wet-laid tissue products having improved physical properties, such as improved bulk.