Tissue Paper Nanofilament Composition for Strength-Softness Balance
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Solution Overview
Problem
Formulators of tissue and towel paper products face challenges in balancing strength, absorbency, and softness, as increasing one property often negatively affects the others, particularly in achieving high wet and dry strength without compromising softness and absorbency, especially in multi-density structures.
Innovation Solution
A process involving a papermaking furnish with a refined softwood pulp fiber mixture, cellulose nanofilaments, hardwood pulp fibers, and optional additives, which allows for the reduction of softwood content while maintaining strength and improving absorbency and softness, through specific weight percentages and processing methods such as through-air drying.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If softwood fiber content is increased to achieve adequate strength, then dry strength is improved, but softness and absorbency deteriorate
Solution Approach 1:
The patent uses a composite fibrous structure combining softwood fibers, hardwood fibers, and cellulose nanofilaments. This composite approach allows the softwood fibers to provide strength while the hardwood fibers and nanofilaments contribute to softness and absorbency, resolving the contradiction between strength and softness
Solution Approach 2:
The patent creates multi-density structures with different regions having different fiber compositions. By locally optimizing fiber distribution and density, areas requiring strength have higher softwood content while areas requiring softness have higher hardwood content, allowing both properties to coexist
2Strength
If softwood fiber content is increased to achieve adequate strength, then dry strength is improved, but absorbency deteriorates
Solution Approach 1:
The composite fibrous structure combines softwood fibers for strength with hardwood fibers and cellulose nanofilaments that enhance absorbency. The nanofilaments specifically contribute to liquid absorption while the hardwood fibers maintain bulk and softness, resolving the contradiction between strength and absorbency
3Strength
If typical paper making process variables are used to increase wet strength, then in-use strength is improved, but softness and absorbency deteriorate
Solution Approach 1:
The patent changes the fundamental parameters of the papermaking system by incorporating cellulose nanofilaments and using multi-density structures, rather than relying on traditional process variables. This allows wet strength improvement without the typical trade-off in softness and absorbency
4Ease of operation
If softwood fiber content is reduced below 20% to improve softness and absorbency, then softness and absorbency are improved, but sheet strength and reliability deteriorate
Solution Approach 1:
The composite fibrous structure with cellulose nanofilaments enables reduced softwood content while maintaining strength. The nanofilaments provide bonding reinforcement that compensates for lower softwood content, allowing high softness and absorbency without sacrificing reliability
Solution Approach 2:
Cellulose nanofilaments act as an intermediary bonding agent between hardwood and softwood fibers, enabling strong sheet formation even with reduced softwood content. The nanofilaments mediate the fiber network structure, maintaining integrity with lower softwood levels
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 process produces fibrous structures with enhanced strength, absorbency, and softness, reducing the negative impact of softwood content on paper machine runnability and desired sheet attributes, effectively addressing the balance of properties in tissue and towel products.
Implementation Method 1
cellulose nanofilaments...enhanced strength, absorbency, and softness
Implementation Method 2
drying said web until said web contains not more than about 10% by weight moisture
Data Source
AI summary
A process for making absorbent towel paper webs is provided. The process has the steps of (a) providing a papermaking furnish having from about 45% to about 90% by weight of the dry fiber basis of the absorbent towel paper web of a refined softwood pulp fiber mixture having from about 20% to about 89.9% by weight of softwood pulp fiber, from about 0.05% to about 20% by weight of cellulose nanofilaments, and from about 0.05% to about 5.0% by weight of strengthening additive, and from about 10% to about 55% by weight of the dry fiber basis of the absorbent towel paper web of a hardwood pulp fiber mixture; (b) forming a wet fibrous web from the paper making furnish; and, (c) drying the web until the web contains not more than about 10% by weight moisture.