Two-Step Aramid Pulp Refining with Water Removal
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Solution Overview
Problem
Conventional processes for producing aramid pulp often result in low specific surface area, high agglomerate content, and inadequate filler retention and green strength, limiting the mechanical properties of the final products.
Innovation Solution
A process involving a first refining step followed by a water removal step and a second refining step, where the aramid concentration is increased in the second step, leading to a higher degree of fibrillation and improved pulp properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single refining step is used to process aramid fiber suspension, then the process is simple and fast, but the specific surface area is low and agglomerate content is high
Solution Approach 1:
The refining process is divided into two separate refining steps with a water removal step in between. The first refining step processes suspension at lower aramid concentration (0.5-3 wt%), followed by water removal to concentrate the fibrillated fibers, then a second refining step at higher concentration (1-20 wt%). This segmentation allows each refining step to operate optimally, achieving high specific surface area (10-50 m²/g) while reducing agglomerate content below 10%
Solution Approach 2:
The first refining step performs preliminary fibrillation of aramid fibers at lower concentration before water removal. This preliminary action creates a foundation of fibrillated fibers that are then further processed in the second refining step, enabling progressive refinement that achieves high specific surface area without excessive process complexity
2Strength
If aramid concentration is kept low throughout the refining process, then the suspension remains fluid and easy to handle, but the degree of fibrillation is insufficient and green strength is low
Solution Approach 1:
The aramid concentration in the suspension is dynamically adjusted through the process stages. The first refining step uses lower concentration (0.5-3 wt%) for easier handling and initial fibrillation. After water removal, the concentration increases to (1-20 wt%) for the second refining step, enabling high green strength (above 1.0 J/mm²) while maintaining operational ease through staged concentration changes
Solution Approach 2:
The water removal step changes the concentration parameter from low (0.5-3 wt%) to high (1-20 wt%). This parameter change enables the second refining step to achieve high green strength and degree of fibrillation, while the process maintains ease of operation by performing water removal between steps when the suspension can be temporarily concentrated
3Reliability
If multiple refining steps are implemented without water removal, then the process is continuous and simple to operate, but the filler retention is low and mechanical properties are inadequate
Solution Approach 1:
The water removal step between the two refining steps performs a preliminary concentration action that prepares the fibrillated fibers for the second refining step. This preliminary concentration improves filler retention (above 80%) by ensuring proper fiber-filler interaction in the second refining step, while the overall process remains efficient with only one intermediate water removal operation
Solution Approach 2:
Excess water is discarded between the two refining steps through the water removal step, which temporarily concentrates the suspension. This discarding of water improves filler retention and mechanical properties, while the process maintains productivity by quickly removing water and proceeding to the second refining step without prolonged processing time
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 aramid pulp with a high specific surface area, low agglomerate content, high filler retention, and enhanced green strength, resulting in improved mechanical properties of the final products, such as paper and friction applications.
Implementation Method 1
the fibers are pulled apart to form the fibrils, whether or not attached to a thicker stem
Implementation Method 2
The refiner fibrillates and further cuts the short fiber fragments
Implementation Method 3
the suspension is filtered or centrifuged to remove liquid water
Implementation Method 4
the suspension is filtered or centrifuged to remove liquid water
Data Source
Figure 1
AI summary
Process for the manufacture of aramid pulp, wherein a suspension in water of aramid fibers with an average fiber length of below 15 mm is subjected to a first refining step, the product from the first refining step is subjected to a water removal step, and the product from the water removal step is subjected to a second refining step.