Ionic Liquid Cellulose Fiber Spinning Process
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Solution Overview
Problem
Current cellulose fiber production methods, such as the Viscose and Lyocell processes, face challenges including environmental concerns, limited versatility, and high energy costs due to the use of hazardous solvents like NMMO, which are prone to thermal runaway reactions and solvent degradation during recycling.
Innovation Solution
A process using ionic liquids with a cationic 1,5,7-triazabicyclo[4.4.0]dec-5-enium moiety and specific anions, like 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-enium acetate, for dissolving pulp and spinning cellulose fibers, offering enhanced hydrothermal stability and visco-elastic properties for dry jet wet spinning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If NMMO monohydrate is used to dissolve wood pulp for Lyocell fiber production, then the fiber can be produced with high tensile strength, but the solvent is prone to thermal runaway reactions and degradation during recycling
Solution Approach 1:
The patent changes the chemical parameters of the solvent system by replacing NMMO with ionic liquids having specific chemical structures (imida-zolium, pyridinium, pyrrolidinium, or ammonium cations with specific anions). These parameter changes in solvent composition eliminate thermal runaway reactions while maintaining the ability to dissolve cellulose and produce high-strength fibers through dry-jet wet spinning.
Solution Approach 2:
The invention uses composite ionic liquid systems combining specific cation-anion pairs that work synergistically to dissolve cellulose effectively. The composite nature of these ionic liquids provides both the solvation power needed for high-strength fiber production and the thermal stability required for safe recycling, resolving the contradiction between strength and reliability.
2Quantity of substance
If conventional ionic liquids like imidazolium-based halides are used to dissolve cellulose, then cellulose can be dissolved, but the solvents require high processing temperatures which leads to pronounced degradation of the cellulose
Solution Approach 1:
The patent modifies the physical-chemical parameters of the ionic liquid system by selecting specific anions (carboxylates, sulfonates, phosphonates, or alkyl sulphates) paired with appropriate cations. These parameter changes reduce the processing temperature from high temperatures to moderate temperatures (below 100°C), enabling cellulose dissolution without pronounced degradation while maintaining effective dissolution capacity.
3Quantity of substance
If 1-ethyl-3-methylimidazolium acetate is used as the ionic liquid, then cellulose dissolution is achieved, but the solutions show inferior viscoelastic properties for fiber spinning
Solution Approach 1:
The patent changes the chemical structure parameters of the ionic liquid by exploring different cation-anion combinations beyond 1-ethyl-3-methylimidazolium acetate. Specifically, it uses imidazolium, pyridinium, pyrrolidinium, or ammonium cations with carboxylate, sulfonate, phosphonate, or alkyl sulphate anions. These structural parameter changes optimize the viscoelastic properties of the cellulose solution, making it suitable for dry-jet wet spinning while maintaining dissolution efficiency.
4Productivity
If the Viscose process is used to produce man-made cellulosic fibers, then large-scale production is achieved, but hazardous byproducts such as SOx and H2S gases are generated
Solution Approach 1:
The patent eliminates the harmful chemical reactions of the Viscose process by replacing the hazardous CS2 and caustic system with ionic liquids. The ionic liquid system converts the harmful chemical transformation into a benign physical dissolution process, allowing large-scale fiber production without generating SOx, H2S, or other hazardous byproducts, thus maintaining productivity while removing environmental harm.
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 cellulose fibers with superior mechanical properties, reduced thermal stress, and increased hydrolytic stability, surpassing commercially available Lyocell fibers, while ensuring safer and more cost-effective processing with minimal solvent degradation during recycling.
Implementation Method 1
dissolving pulp in an ionic liquid containing a cationic 1,5,7-triazabicyclo[4.4.0]dec-5-enium [TBDH]+ moiety
Implementation Method 2
extruding the spinning dope through a spinneret to form one or more filaments
Data Source
AI summary
According to an example aspect of the present invention, there is provided A process for making a cellulose fibre or film comprising the steps of dissolving pulp in an ionic liquid containing a cationic 1,5,7-triazabicyclo[4.4.0]dec-5-enium [TBDH]+ moiety and an anion selected from the group according to Formula a), Formula b) and Formula c), wherein each of R, R2, R3, R4, R5, R7, R8, R9 and R10 is H or an organyl radical and X− is selected from the group consisting of halides, pseudohalides, carboxylates, alkyl sulphite, alkyl sulphate, dialkylphosphite, dialkyl phosphate, dialkyl phosphonites and dialkyl phosphonates, to provide a spinning dope, extruding the spinning dope through a spinneret to form one or more filaments, and a step selected from the group consisting of spinning cellulose fibres from the solution, and extruding a cellulose film from the solution.