Tissue Pulp Fractionation for Strength and Softness
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Solution Overview
Problem
Current methods for producing cellulose pulps that enhance both strength and softness in consumer tissue and towel products face challenges, as increased strength typically results in decreased softness, and the scarcity of native softwood fibers necessitates the use of lower quality fibers which compromise strength characteristics.
Innovation Solution
A process involving the width-wise fractionation of cellulose pulps using methods like hydraulic cyclones and apertured screens to separate fibers by size and shape, reducing the number of vessel elements, which enhances both the wet tensile strength and softness of the final products.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the intrinsic strength of consumer tissue or towel product is increased, then the strength increases, but the overall softness decreases
Solution Approach 1:
The patent applies segmentation by separating vessel elements from fibers through width-wise fractionation. This divides the heterogeneous pulp into distinct size-based fractions, allowing selective retention of fibers while removing vessels that negatively impact softness, thereby resolving the strength-softness tradeoff
Solution Approach 2:
The patent extracts vessel elements from the pulp furnish using extraction techniques such as hydrocyclones and screens. By removing the harmful component (vessels) while retaining beneficial fibers, the process achieves improved softness without sacrificing strength
2Ease of manufacture
If native softwood fibers are replaced with lower cost and more abundant sources of cellulose, then cost decreases and availability increases, but the strength characteristics of paper deteriorate
Solution Approach 1:
The patent changes the morphological parameters of the furnish by controlling fiber size distribution through fractionation. By optimizing the size distribution and removing vessels, lower quality fibers can achieve strength characteristics comparable to or exceeding those of premium softwood fibers
Solution Approach 2:
The patent creates a composite furnish structure by combining fractionated fibers with controlled morphology. This composite approach allows mixing of different fiber sources while maintaining uniform performance characteristics through standardized size distribution
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 achieves unachievable levels of strength and softness in fibrous structures, providing consumer tissue and towel products with improved user experience by optimizing fiber morphology and vessel content.
Implementation Method 1
One method described herein can be used for the centrifugal separation of fibers having different apparent specific gravities
Implementation Method 2
The resulting fractions can yield a pulp that can be used to produce a web product
Implementation Method 3
One method described herein can be used for the centrifugal separation of fibers having different apparent specific gravities (e.g., by classifying fibers by width)
Data Source
AI summary
A sanitary tissue product may comprise a first layer comprising eucalyptus fibers and a second layer comprising eucalyptus fibers and softwood fibers. The eucalyptus fibers in the second layer may have at least 24% more vessel elements than the eucalyptus fibers in the first layer.