Fibril Cellulose Membrane Drying via Coagulation and Heat
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge lies in efficiently producing fibril cellulose membranes with uniform structure and suitable for industrial production, as conventional methods face issues with slow drying times due to the dense and impermeable nanoscale membrane formed by fibril cellulose hydrogels, particularly with anionically charged grades which exhibit high water retention capacity.
Innovation Solution
A method involving the use of a filter fabric impermeable to fibrils but permeable to liquid, where liquid is drained under reduced pressure, followed by heat application on the opposite side of the membrane sheet to enhance drying, allowing for the formation of a freestanding membrane with reduced drying time, and optionally pretreating anionically charged fibril cellulose by lowering pH to reduce water retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional vacuum filtration is used to remove water from fibril cellulose dispersion, then water removal is achieved, but drying time becomes very long (several hours)
Solution Approach 1:
The patent applies preliminary action by using a coagulating agent before vacuum filtration to modify the fibril cellulose structure. This pre-treatment causes the fibrils to coagulate and form a more open structure that facilitates faster water removal during subsequent drying, thus resolving the contradiction between water removal effectiveness and drying time
Solution Approach 2:
The patent introduces a coagulating agent as an intermediary substance that mediates between the fibril cellulose and water. This intermediary causes structural changes in the fibril network that improve water removal kinetics, enabling faster drying without compromising the membrane formation process
2Reliability
If anionically charged fibril cellulose is used, then membrane formation capability is improved, but water retention capacity increases causing longer dewatering times
Solution Approach 1:
The patent applies preliminary anti-action by adding a coagulating agent that counteracts the electrostatic repulsion between anionically charged fibrils. This pre-treatment neutralizes the charges and promotes fibril aggregation, preventing the formation of dense impermeable structures and enabling faster dewatering while maintaining membrane formation capability
Solution Approach 2:
The patent changes the electrostatic parameter of the fibril cellulose system by introducing a coagulating agent that neutralizes anionic charges. This parameter change transforms the system from highly repulsive to less repulsive or attractive, fundamentally altering the water retention characteristics and dewatering behavior
3Manufacturing precision
If low consistency dispersion is used to form thin membranes with uniform structure, then membrane uniformity is improved, but water removal time increases
Solution Approach 1:
The patent applies preliminary action by coagulating the fibril cellulose before membrane formation. This pre-treatment creates a more open and uniform fibril network structure that maintains membrane uniformity while significantly reducing the time required for water removal, thus resolving the contradiction between uniformity and drying 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
This method significantly reduces drying time, enabling the production of fibril cellulose membranes that are feasible for industrial use, even with anionically charged grades, by forming a fibril network that aids in water removal and maintaining membrane integrity.
Implementation Method 1
draining the liquid by the effect of reduced pressure through a filter fabric
Implementation Method 2
through a filter fabric impermeable to fibrils of the fibril cellulose but permeable to the liquid
Implementation Method 3
The heat applied on the opposite side of the membrane sheet being formed through draining can be accomplished by contact (conduction) with a heated surface
Implementation Method 4
or by irradiation of the surface of the membrane sheet (radiation heat)
Implementation Method 5
to promote the removal of the liquid in liquid state
Data Source
AI summary
Method for preparing a membrane from fibril cellulose includes supplying fibril cellulose dispersion on a filter layer, draining liquid from a fibril cellulose dispersion by the effect of reduced pressure through the filter layer that is impermeable to fibrils of the fibril cellulose but permeable to the liquid to form a membrane sheet on the filter fabric, applying heat on the opposite side of the membrane sheet to the membrane sheet while continuing draining of the liquid through the filter layer by pressure difference over the filter layer, and removing the membrane sheet from the filter layer as a freestanding membrane.