Regenerated Biopolymer Fiber Coagulation via Ionic Liquid Surface Tension Control
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Solution Overview
Problem
Current methods for regenerating biopolymers like cellulose face challenges such as high waste production, unwanted emissions, and energy-intensive water separation in ionic liquid solutions, limiting their technical implementation due to narrow solution windows and fibrillation issues in products.
Innovation Solution
The method involves using a molten ionic liquid solution system with a protic coagulant having a surface tension between 35% and 99% of water's surface tension at 50°C, specifically selecting hexan-1-ol to dodecan-1-ol or their mixtures, to precipitate biopolymers like cellulose, optimizing the wet and dry strength of spun fibers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional solvent systems (viscose process) are used for cellulose regeneration, then processing capability is achieved, but large amounts of salts and sulfur-containing exhaust gases are produced requiring follow-up treatment
Solution Approach 1:
The patent changes the chemical parameters of the solvent system by replacing conventional viscose solvents (CS2, NaOH) with ionic liquids containing specific cations (imidazolium, pyridinium, ammonium) and anions (halides, pseudohalides, sulfonates, carboxylates). This parameter change eliminates sulfur-containing exhaust gases and reduces salt production while maintaining cellulose dissolution and regeneration capabilities.
Solution Approach 2:
The patent employs ionic liquids as replaceable, environmentally friendly solvent systems that can be used in controlled amounts and then regenerated or disposed of without producing persistent harmful waste. The ionic liquid solvent system replaces long-lived harmful substances (sulfur compounds, large salt quantities) with a more controllable and treatable medium.
2Object-generated harmful factors
If NMMO solvent system is used for direct cellulose solution, then waste and emissions are reduced, but the solution window is narrow and system-related fibrillation occurs
Solution Approach 1:
The patent changes the solvent system parameters from NMMO (a single oxidizing solvent with narrow solution window) to ionic liquids with adjustable cation-anion combinations. This provides a broader and more tunable solution window, allowing precise control over cellulose dissolution and regeneration while preventing fibrillation through appropriate ionic liquid selection.
Solution Approach 2:
The patent uses composite ionic liquid systems combining specific cations (imidazolium, pyridinium, ammonium) with specific anions (halides, pseudohalides, sulfonates, carboxylates) to create a synergistic solvent system. This composite approach provides both the environmental benefits of reduced waste and the manufacturing precision needed to control solution behavior and prevent fibrillation.
3Object-generated harmful factors
If ionic liquids are used for cellulose dissolution, then conventional solvent disadvantages are overcome, but water separation becomes extremely energy-intensive and economically inefficient
Solution Approach 1:
The patent changes the ionic liquid composition parameters by selecting specific hydrophobic ionic liquids (with long-chain alkyl groups or fluorinated substituents) that have inherent water immiscibility. This parameter change allows easy phase separation from water without energy-intensive distillation, as the ionic liquid forms a separate phase that can be mechanically decanted or centrifuged.
Solution Approach 2:
The patent employs ionic liquids with built-in water separation capabilities that eliminate the need for energy-intensive water removal. The ionic liquid can be used in controlled cycles where water content is naturally limited by phase separation, making the process economically efficient without requiring large energy inputs for water separation.
4Productivity
If protic coagulants with surface tension close to water are used, then coagulation efficiency is maintained, but wet strength of spun fibers is insufficient
Solution Approach 1:
The patent changes the surface tension parameter of the coagulant from near-water values (high surface tension) to significantly lower values (35-99% of water's surface tension at 50°C). This parameter change improves wet strength by modifying the coagulation kinetics and fiber morphology, while coagulation efficiency is maintained through optimization of other parameters such as coagulant composition, temperature, and addition rate.
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 non-fibrillating spinning fibers with enhanced maximum tensile strength, reduced sulfur content, and improved water retention capacity, overcoming previous limitations in biopolymer regeneration processes.
Implementation Method 1
the biopolymers dissolved in the solution system are precipitated in a coagulation medium, the coagulation medium containing a protic coagulant or a mixture of protic coagulants
Implementation Method 2
the surface tension σ of the protic coagulant or the mixture of protic coagulants is 99% to 35% of the surface tension σ of water
Data Source
AI summary
The invention relates to a method for producing regenerated biopolymers in the form of carbohydrates, using a solvent system that contains the biopolymers dissolved therein. The solvent system is based on a melted ionic liquid and optionally a protic solvent or a mixture thereof. The biopolymers dissolved in the solvent system are precipitated in a coagulation medium, said medium comprising a protic coagulant or a mixture of protic coagulants. The method according to the invention is characterized in that the surface tension s of the coagulant or the mixture of coagulants is 99% to 30% of the surface tension s of water, the surface tension being measured according to ASTM D 1590-60 at a temperature of 50°C. The method according to the invention is economical and flexible and leads to advantageous products, especially in the form of staple fibers which are especially not fibrillated and have an advantageous wet to dry strength ratio.