Paper And Board Barrier Coating via Air-Gap Cellulose Casting
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Solution Overview
Problem
Existing methods for manufacturing barrier coatings on paper and carton boards using dissolved cellulose face challenges such as unsafe operating conditions, difficulty in controlling casting quality, and high material requirements, particularly when using sulphuric acid coagulation baths.
Innovation Solution
A method involving casting dissolved cellulose from a nozzle to air and a support, followed by regeneration in sodium carbonate or sodium hydrogen carbonate solutions, which replaces the traditional sulphuric acid bath, enhancing safety and control over casting quality while reducing material demands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sulphuric acid coagulation bath is used for regeneration, then cellulose dissolution and regeneration can be achieved, but operating safety deteriorates and material requirements increase
Solution Approach 1:
The patent changes the chemical parameter of the coagulation bath from sulphuric acid to sodium carbonate or sodium hydrogen carbonate solutions, fundamentally altering the chemical environment from highly acidic to alkaline/neutral conditions. This parameter change maintains the coagulation function while eliminating the safety hazards associated with sulphuric acid handling and operation
Solution Approach 2:
The patent converts the traditionally harmful acidic environment into a beneficial alkaline environment using sodium carbonate or sodium hydrogen carbonate. This not only eliminates safety hazards but also provides additional benefits such as improved casting quality control and reduced material requirements, turning a previously harmful condition into a beneficial one
2Reliability
If casting from nozzle to liquid is used, then regeneration can occur, but control of casting quality deteriorates and device complexity increases
Solution Approach 1:
The patent segments the casting and regeneration processes into two distinct stages: first casting the dissolved cellulose from nozzle to air to form a free-standing film, then separately performing regeneration by submerging the formed film into the coagulation bath. This segmentation eliminates the counter-pressure problem that occurs when casting directly into liquid, allowing for much better control of casting quality, thickness uniformity, and impurity distribution
Solution Approach 2:
The patent introduces air as an intermediary medium between the nozzle and the coagulation bath. By casting through air rather than directly into liquid, the dope can exit the nozzle freely without counter-pressure resistance, enabling precise control over film formation while the air gap acts as a buffer that separates the casting operation from the regeneration operation
3Reliability
If slot die is sunk into regeneration liquid, then regeneration can occur, but ease of operation deteriorates and cleaning difficulty increases
Solution Approach 1:
Instead of submerging the slot die into the regeneration liquid as in traditional methods, the patent inverts the approach by forming the film in air first and then submerging only the formed film into the coagulation bath. This inversion completely eliminates the operational difficulties of handling slot dies in liquid, making the equipment much easier to operate, clean, and maintain
4Reliability
If sulphuric acid coagulation bath is used, then regeneration can occur, but material costs and environmental impact increase
Solution Approach 1:
The patent changes the chemical composition parameter of the coagulation bath from expensive and environmentally problematic sulphuric acid to more economical and environmentally friendly sodium carbonate or sodium hydrogen carbonate solutions. This parameter change reduces material costs, simplifies waste treatment, and improves overall process sustainability while maintaining effective regeneration
Solution Approach 2:
The patent converts the traditionally harmful and expensive sulphuric acid system into a beneficial alkaline system using sodium carbonate or sodium hydrogen carbonate. This not only reduces material costs and environmental impact but also provides additional operational benefits including improved safety and compatibility with carbonate pigments, turning a previously harmful and expensive approach into a beneficial and economical one
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 approach results in improved barrier properties against oxygen, water vapor, and grease, with enhanced mechanical properties and safer operating conditions, achieving approximately 20% higher mechanical strength compared to sulphuric acid-based methods.
Implementation Method 1
leading the formed film, coated paper or coated carton board into a regeneration coagulation bath comprising sodium carbonate or sodium hydrogen carbonate
Data Source
AI summary
According to an example aspect of the present invention, there is provided method for manufacturing a barrier layer on top of a paper or carton board from dissolved cellulose, which combines the benefits of the raw material, improved casting method and replacement of sulphuric acid with sodium carbonate or sodium hydrogen carbonate in regeneration bath.