Ultra-high-count PI-PSA Electrospun Yarn Preparation
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Solution Overview
Problem
Current electrostatic spinning technology is limited in producing ultra-high-count filament yarns of PI/PSA composite fibers with excellent mechanical properties and high temperature resistance, as it primarily manufactures non-woven fabrics with low areal density and discontinuous, thick yarns with counts less than 150.
Innovation Solution
A process involving the purification of monomers, formation of a polyamic acid solution with PSA, electrostatic spinning, thermal drafting and imidization, and twisting to produce ultra-high-count filament yarns with specific monomer structures, solvent systems, and processing parameters to achieve high orientation and continuous length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If electrostatic spinning is used to manufacture non-woven fabrics or spray thin layer of nano-cobweb, then the areal density is low (about 1 g/m2), but the yarn count is less than 150 and the yarn is discontinuous and thick
Solution Approach 1:
The patent divides the electrospun mat into multiple thin layers and processes them through a multi-stage thermal drafting system with 4-6 drafting rolls, where each stage progressively drafts and aligns the fibers. This segmentation approach transforms the original discontinuous non-woven fabric into continuous high-count filament yarn with counts exceeding 150, while maintaining the low areal density characteristic of electrospun materials.
Solution Approach 2:
The patent transitions from producing two-dimensional non-woven fabrics to creating one-dimensional continuous filament yarns by introducing thermal drafting and imidization processes. This dimensional transformation enables the material to progress from a mat structure to spinnable continuous fibers with high orientation and count, resolving the contradiction between low areal density and high yarn count.
2Quantity of substance
If conventional electrostatic spinning is applied, then non-woven fabrics with low areal density are produced, but ultra-high-count filament yarns with continuous length and high orientation cannot be achieved
Solution Approach 1:
The patent performs preliminary imidization treatment on the electrospun polyamic acid mat before drafting, by heating it to 200-400°C to convert polyamic acid to polyimide. This preliminary chemical transformation strengthens the fibers and improves their thermal stability, enabling subsequent high-temperature drafting processes that achieve high fiber orientation and continuous yarn formation without compromising the low areal density.
Solution Approach 2:
The patent systematically changes multiple parameters including temperature (200-400°C for imidization, up to 500°C for drafting), drafting ratio (cumulative ratio of 3:1 to 10:1), and residence time in the thermal field. These parameter changes transform the electrospun mat from a disorganized low-density structure into highly oriented continuous filament yarn while preserving the low areal density characteristic.
3Quantity of substance
If electrostatic spinning produces non-woven fabrics, then the areal density is low, but the mechanical properties and high temperature resistance are insufficient
Solution Approach 1:
The patent creates a composite structure by combining electrospun polyamic acid or polyimide fibers with polysulfonamide (PSA) fibers through the drafting process. This composite formation enhances the mechanical strength and high-temperature resistance of the final yarn while maintaining the low areal density advantage of electrospun materials, as the PSA component provides additional structural reinforcement.
Solution Approach 2:
The patent utilizes phase transition from polyamic acid to polyimide through thermal imidization (200-400°C) to fundamentally change the material properties. This phase transition increases the thermal stability and mechanical strength of the fibers, enabling them to withstand the high-temperature drafting process and resulting in yarns with superior high-temperature resistance while preserving low areal density.
4Productivity
If thermal drafting and imidization are applied to electrospun fiber felt, then continuous length and orientation are improved, but the process complexity increases
Solution Approach 1:
The patent combines the imidization and drafting operations into a single integrated thermal processing step, where the electrospun mat passes through a heating zone that simultaneously performs chemical imidization and mechanical drafting. This merging of operations reduces process complexity compared to separate sequential treatments, while achieving both high continuous length and fiber orientation in one pass through the thermal drafting apparatus.
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 process results in ultra-high-count filament yarns with 500-1500 metric counts and over 2000 meters in length, offering excellent mechanical properties and overcoming the limitations of existing technologies in producing continuous, high-count electrospun fibers.
Implementation Method 1
step 2: implementing electrostatic spinning to the spinning raw material liquid in a high-voltage electric field
Implementation Method 2
step 3: cutting the polyamic acid/PSA electrospun fiber felt or nonwoven fabric obtained above into slender strips with a width of 0.5 to 5.0 cm, and thermally drafting and imidizing the strips to form an oriented electrospun fiber bundle
Data Source
AI summary
The present invention relates to the technical field of chemical fiber spinning, in particular to a process for preparing an ultra-high-count filament yarn of PI-PSA electrospun fiber and uses thereof, the process comprises the steps of: step 1: after a monomer (I) and a monomer (II) are purified, adding the monomer (I) and monomer (II) to a polymerization reactor together with a solvent to obtain a polyamic acid solution, which is then mechanically mixing the polyamic acid solution with a PSA to obtain a spinning raw material liquid of the polyamic acid and the PSA; step 2: implementing electrostatic spinning to the spinning raw material liquid in a high-voltage electric field, and collecting to obtain a felt or nonwoven fabric of polyamic acid/PSA electrospun fibers using a stainless steel mesh belt as a collector; step 3: cutting the felt or nonwoven fabric of polyamic acid/PSA electrospun fibers obtained above into slender strips with a width of 0.5 to 5.0 cm, and thermally drafting and imidizing the strips to form an oriented electrospun fiber bundle; step 4: twisting the above electrospun fiber bundle to obtain an ultra-high-count filament yarn of PI-PSA electrospun composite fiber.