Regenerated Cellulose Microfibers via Bicomponent Spinnerets
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for producing cellulose microfibers from lyocell fibers face inefficiencies due to fibrillation tendencies, low coarseness, and high production costs, resulting in suboptimal yield and properties of microfibers for absorbent products.
Innovation Solution
A modified method using spinnerets to create segmented fibers with designed defects, allowing for higher yield and longer, lower-coarseness microfibers by extruding cellulose dopes of different compositions through bicomponent spinnerets, and employing ionic liquids to enhance the splitting process, enabling up to 100% microfiber yield from larger fibers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional lyocell fibers are fibrillated to produce microfibers, then microfiber yield is improved, but fiber length is reduced and coarseness is excessively low
Solution Approach 1:
The patent applies preliminary action by introducing controlled defects during the fiber spinning stage rather than relying on subsequent mechanical fibrillation. Bicomponent spinnerets with different dope compositions (e.g., different degrees of polymerization, additives, or solvent ratios) create predetermined weak points in the nascent fiber, which then split into microfibers of controlled length and coarseness without excessive mechanical action that would shorten fibers
2Quantity of substance
If extended low intensity refining is applied to fibrillate lyocell fibers, then microfiber yield is improved, but production time and cost increase
Solution Approach 1:
The invention performs the microfiber formation action during the spinning process itself rather than requiring extended post-spinning refining. The bicomponent spinnerets create fibers with built-in segmentation that split into microfibers immediately upon formation or with minimal subsequent processing, eliminating the need for extended low-intensity refining operations
Solution Approach 2:
The patent extracts the microfiber formation step from the conventional fibrillation process by incorporating defect creation directly into the spinneret design. This separates the microfiber production function from the fiber formation function, allowing microfibers to be produced directly during spinning without requiring subsequent mechanical fibrillation time
3Reliability
If high purity alpha cellulose is used for lyocell production, then fiber quality is improved, but raw material cost increases
Solution Approach 1:
The patent applies local quality by using different cellulose purity levels in different components of the bicomponent system. One dope can contain high purity alpha cellulose for core strength while the other contains lower purity cellulose with controlled impurities that facilitate splitting. This local differentiation allows use of lower-cost materials in portions where high purity is not critical, reducing overall raw material cost while maintaining fiber quality
Solution Approach 2:
The invention changes the purity parameter strategically by accepting lower purity cellulose in one or both dopes and compensating through the bicomponent design. The controlled impurities or compositional differences actually serve the functional purpose of creating splittable interfaces, transforming what would be a quality deficit into a functional advantage that reduces raw material costs
4Quantity of substance
If mechanical action is increased to fibrillate fibers, then microfiber yield is improved, but fibers are ground and shortened
Solution Approach 1:
The patent applies preliminary action by pre-positioning split points during fiber formation rather than relying on mechanical fibrillation. The bicomponent spinnerets create fibers with inherent compositional variations that create weak points along the fiber length, allowing the fiber to split into microfibers of controlled length without subjecting it to intensive mechanical action that would grind and shorten the fibers
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 higher microfiber yield and improved properties such as coarseness and length, allowing for the production of soft yet strong tissue and towel products using lower-cost raw materials like unpurified Kraft pulp, enhancing the tactile benefits and performance of absorbent products.
Implementation Method 1
cellulose dissolved in a solvent composition including an ionic liquid
Implementation Method 2
spinning, that is, extruding the first and second cellulosic dopes through suitable spinnerets
Implementation Method 3
The water dilutes the NMMO as the nascent fiber is drawn through the bath, and the cellulose crystallizes into fibers
Implementation Method 4
the cellulose crystallizes into fibers
Data Source
AI summary
A method of making regenerated cellulose microfibers includes forming segmented fibers with multiple longitudinally-extending segments of slightly different composition such that there is defined splittable interfaces between juxtaposed segments of the fibers which are then split into microfibers at yields of greater than 50%. Fibers so produced may be incorporated into absorbent sheet with other papermaking fibers to provide strength, softness, bulk and absorbency to tissue, towel, and personal care products.