Staged Shear Refining for Fibrillated Fiber Production
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for producing fibrillated fibers are inefficient and costly, failing to effectively produce fibers with nanometer-sized fibrils while retaining extended fiber length and avoiding the generation of fines.
Innovation Solution
A process involving low shear refining followed by higher shear refining of fiber suspensions, with controlled flow rates and heat management, using open channel refiners to increase fibrillation without substantial crushing or cutting, allowing for continuous processing and staged shear rates to achieve desired Canadian Standard Freeness values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If commercial papermaking machinery and blenders are used to produce fibrillated fibers, then the process is simple to operate, but the productivity is low and cost is high
Solution Approach 1:
The refining process is divided into multiple stages with different shear rates. A first refiner applies a first shear rate to create initial fibrillation, and a second refiner applies a second shear rate (higher than the first) to increase the degree of fibrillation. This segmentation allows each stage to be optimized for specific fibrillation requirements, improving overall productivity while maintaining operational simplicity.
2Manufacturing precision
If high shear refining is applied to increase fibrillation, then the degree of fibrillation increases, but fiber length is reduced and fines are generated
Solution Approach 1:
The patent applies different shear rates dynamically across multiple refining stages. The first refiner uses a lower shear rate to create initial fibrillation with minimal fiber length reduction, while the second refiner uses a higher shear rate to increase fibrillation further. This dynamic approach allows the process to adapt shear intensity to the specific fibrillation stage, achieving high fibrillation degrees while preserving fiber length and minimizing fines generation.
3Productivity
If continuous processing is implemented, then productivity increases, but energy consumption increases
Solution Approach 1:
The patent changes the shear rate parameter across different refining stages to optimize energy efficiency. By using a lower first shear rate in the initial stage and a higher second shear rate in the subsequent stage, the process avoids unnecessary energy consumption at high shear rates throughout the entire process. This parameter optimization allows continuous processing to achieve high productivity while maintaining reasonable energy efficiency.
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
This method efficiently produces fibrillated fibers with nanofiber-sized fibrils attached to core fibers, enhancing productivity and yield while maintaining elongated fiber lengths and reducing fines, resulting in improved energy efficiency and cost-effectiveness.
Implementation Method 1
low shear refining the fibers at a first shear rate to create fibrillated fibers, and subsequently higher shear refining the fibers at a second shear rate, higher than the first shear rate, to increase the degree of fibrillation of the fibers
Data Source
AI summary
A process for making fibrillated fibers includes preparing a fluid suspension of fibers, low shear refining the fibers at a first shear rate to create fibrillated fibers having a reduced CSF, and subsequently higher shear refining the fibers at a second shear rate, higher than the first shear rate, to increase the degree of fibrillation of the fibers. The refining at the first shear rate may be with a rotor at a first maximum shear rate and the refining at the second shear rate may be with a rotor at a second maximum shear rate, higher than the first maximum shear rate. The process may further include pre-treating the fibers by high shear refining with impact to stress the fibers prior to low shear refining.