Anionically Modified Cellulose Spinning for High Tensile Strength
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Solution Overview
Problem
Current methods for spinning cellulose fibers face challenges in achieving high tensile strength and are associated with the release of hazardous materials, such as carbon disulphide and hydrogen sulphide, and are unable to produce fibers with tensile strength greater than 85 cN/tex.
Innovation Solution
A method involving the preparation of an anionically modified cellulose suspension with a shear rate exceeding 1000 sec^-1, extrusion through a spinneret into a spinbath containing a cationic complexing agent, and subsequent isolation of spun fibers, utilizing sulfur-derivatized cellulose nanofibrils with controlled degree of substitution and surface charge, to produce fibers with enhanced mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional cellulose spinning methods are used, then the process can be implemented with existing technology, but hazardous materials such as carbon disulphide and hydrogen sulphide are released
Solution Approach 1:
The invention changes the chemical parameters of the spinning system by using anionically modified cellulose (sulfated or sulfonated) instead of conventional cellulose, and employs a cationic complexing agent in the spin bath. This parameter change transforms the chemical reactions involved, eliminating the release of hazardous sulfur-containing gases while maintaining the spinning process functionality.
Solution Approach 2:
The invention converts the potentially harmful sulfur groups on the cellulose (which could lead to hazardous gas release) into a beneficial feature by using them for controlled interaction with cationic complexing agents. The anionic sulfur groups that could cause harm are instead used to create stable complexes with metal cations, achieving both safe operation and desired fiber formation.
2Productivity
If conventional spinning systems are used, then the manufacturing process can proceed, but very high tensile strengths greater than 85 cN/tex cannot be achieved
Solution Approach 1:
The invention achieves superior tensile strength by changing multiple parameters: using nanofibrillar cellulose morphology, applying anionic modification (sulfation/sulfonation), controlling degree of substitution, and optimizing the cationic complexing agent concentration. These parameter changes collectively enable tensile strengths exceeding 85 cN/tex, breaking the limitation of conventional systems.
Solution Approach 2:
The invention creates a composite structure through the interaction between anionically modified cellulose nanofibrils and cationic complexing agents. This composite approach, where the cellulose matrix is enhanced by metal cation complexes, produces fibers with exceptional mechanical properties including very high tensile strength, combining the benefits of both components.
3Strength
If the degree of substitution of sulfur groups is increased to improve mechanical properties, then tensile strength increases, but the risk of hazardous material release increases
Solution Approach 1:
The invention resolves this contradiction by converting the high-density sulfur groups (which could release hazardous gases) into stable anionic sites that bind cationic complexing agents. The sulfur groups that pose a risk are instead utilized to create strong electrostatic interactions with metal cations, achieving high tensile strength through controlled complexation rather than through hazardous chemical reactions.
Solution Approach 2:
The cationic complexing agent acts as an intermediary that mediates between the anionic sulfur groups on cellulose and the desired mechanical properties. Instead of allowing direct reactions that could produce hazardous gases, the cationic agent intermediates the interaction, forming stable complexes that provide strength without releasing harmful substances.
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 method achieves high tensile strength in cellulose fibers while minimizing the release of hazardous substances, with the sulfur-derivatized cellulose nanofibrils exhibiting improved mechanical properties and controlled surface charge, enabling the production of fibers with tensile strength exceeding 85 cN/tex.
Implementation Method 1
subjecting the suspension to a shear rate of more than 1000 sec-1
Implementation Method 2
performing spinning by extruding cellulose suspension through spinneret into a spinbath comprising a cationic complexing agent
Data Source
AI summary
The present invention is directed towards a method for spinning anionically modified cellulose comprising the steps of: (a) preparing a suspension of the anionically modified cellulose in a continuous phase; (b) subjecting the suspension to high shear rate; (c) performing spinning by extruding the cellulose suspension through a spinneret into a spin bath comprising a cationic complexing agent, and (d) isolating the spun fibres from the spin bath; as well as fibres obtained based on the method of the invention and paper or board products derived from such fibres.