Cold-alkali Cellulose Fiber Crosslinking to Reduce Fibrillation
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Solution Overview
Problem
Regenerated cellulosic fibers produced by the cold-alkali process exhibit a strong tendency to fibrillate, which affects their mechanical properties and processing capabilities, and existing methods to address this often compromise fiber quality and efficiency.
Innovation Solution
A method involving the extrusion of a spinning solution containing cellulose in an aqueous NaOH and ZnO solvent into a coagulation bath with a pH of at least seven, followed by the application of a crosslinking agent with two or more reactive groups to the never-dried fibers, and subsequent heating to a curing temperature, reduces fibrillation while maintaining the mechanical properties of the fibers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If crosslinking treatment is applied to reduce fibrillation, then fibrillation tendency is reduced, but fiber embrittlement occurs
Solution Approach 1:
The patent applies parameter changes by carefully controlling the crosslinking process conditions including temperature, time, and crosslinking agent concentration to achieve optimal reduction of fibrillation while preventing fiber embrittlement. The crosslinking is performed at controlled temperatures and for specific durations to modify the fiber structure without excessive crosslinking that would cause embrittlement.
Solution Approach 2:
The crosslinking treatment is applied selectively to address the specific problem of fibrillation in cold-alkali regenerated cellulosic fibers. The treatment modifies the local structure of the fiber where fibrillation occurs, creating crosslinked regions that prevent fibril separation while maintaining the overall fiber flexibility and processability.
2Manufacturing precision
If extensive washing is performed to remove chemicals, then fiber purity is improved, but processing time and complexity increase
Solution Approach 1:
The patent extracts and removes excess crosslinking agent and other chemicals from the fiber through washing steps. The washing process is optimized to remove harmful residues while maintaining the crosslinked structure that provides fibrillation resistance, achieving a balance between purity and processing efficiency.
Solution Approach 2:
The crosslinking treatment is performed on never-dried fibers before complete drying, which facilitates easier removal of chemicals during subsequent washing steps. The moisture present in the never-dried fibers helps in the washing process, reducing the time and complexity required for chemical removal while ensuring fiber purity.
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 effectively reduces the fibrillation tendency and maintains the tensile strength and elongation of cold-alkali fibers, preventing embrittlement and enabling easier processing into yarns, while allowing for reduced washing steps and improved alkaline recycling.
Implementation Method 1
extruding a spinning solution containing cellulose in an aqueous solvent comprising NaOH and ZnO into a coagulation bath which contains a salt and preferably an alkali to produce the fibers
Implementation Method 2
application of a crosslinking agent with two or more reactive groups to the never-dried fibers, and subsequent heating to a curing temperature, reduces fibrillation while maintaining the mechanical properties of the fibers
Implementation Method 3
subsequent heating to a curing temperature, reduces fibrillation while maintaining the mechanical properties of the fibers
Data Source
AI summary
A method and processing facility for producing regenerated cellulosic fibers includes extruding a spinning solution into a coagulation bath which contains a salt and preferably an alkali to produce the fibers. The spinning solution may include cellulose dissolved in an aqueous solvent comprising NaOH and ZnO. The coagulation bath may have a pH-value of at least seven. The method may also include a continuous process of applying to the fibers in a never-dried state a crosslinking agent with two or more reactive groups and heating the fibers to a curing temperature while maintaining the never-dried condition to produce a reaction between the crosslinking agent and the cellulose of the fiber.