Polyamide Nanofiber Nonwovens via Propellant-Gas Spinning
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Solution Overview
Problem
Conventional methods for producing polyamide nanofibers are expensive and unable to achieve the desired fiber diameter and surface area to volume ratio, leading to suboptimal manufacturing costs and product properties.
Innovation Solution
A method involving a polyamide composition with a relative viscosity of 2 to 330, spun into nanofibers with an average diameter of 100 to 1000 nanometers using a 2-phase propellant-gas spinning process, which reduces oxidative and thermal degradation indices and eliminates the need for solvents, thereby improving durability and reducing production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If electrospinning is used to produce nanofibers, then fiber diameter and surface area to volume ratio are improved, but manufacturing cost increases
Solution Approach 1:
The patent changes the fundamental processing parameters by transitioning from solution-based electrospinning to melt-based processing. This involves changing the state of the polymer (from dissolved to melted), the driving force (from electrical field to mechanical shear and pressure), and the processing temperature (from ambient to elevated). These parameter changes enable production of nanofibers with controlled diameters while eliminating the high costs associated with electrospinning equipment and operation.
2Ease of manufacture
If conventional melt-blowing is used to produce nanofibers, then manufacturing cost is reduced, but fiber diameter control and nanofiber size achievement are insufficient
Solution Approach 1:
The patent introduces a dual-spinneret system where an inner spinneret delivers polymer melt and an outer spinneret delivers a shearing gas or air stream. This intermediary gas stream acts as a mediator that shears the polymer melt into fine nanofibers as it exits the die, enabling precise fiber diameter control while maintaining the cost-effectiveness of melt-based processing. The intermediary medium transfers energy and momentum to achieve the desired fiber morphology.
3Ease of manufacture
If centrifugal-spinning is used to produce nanofibers, then manufacturing cost is reduced, but fiber diameter distribution and nanofiber quality are insufficient
Solution Approach 1:
The patent implements local quality control through the spinneret design where different regions of the die face produce fibers with specific diameter characteristics. By controlling the geometry, temperature, and shear conditions at each location on the spinneret surface, the process achieves narrow fiber diameter distributions. Each local region on the spinneret is optimized to produce consistent nanofiber dimensions, ensuring overall product uniformity while maintaining cost-effective melt processing.
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 nanofibers with improved durability and reduced production costs, achieving smaller diameters and higher surface area to volume ratios, enhancing the performance of nanofiber nonwoven products for various applications.
Implementation Method 1
A method involving a polyamide composition with a relative viscosity of 2 to 330, spun into nanofibers with an average diameter of 100 to 1000 nanometers using a 2-phase propellant-gas spinning process
Data Source
AI summary
A nanofiber nonwoven product is disclosed which comprises a polyamide with a relative viscosity from 2 to 330, spun into nanofibers with an average diameter of less than 1000 nanometers (1 micron). In general, the inventive products are prepared by: (a) providing a polyamide composition, wherein the polyamide has a relative viscosity from 2 to 330; (b) melt spinning the polyamide composition into a plurality of nanofibers having an average fiber diameter of less than 1 micron, followed by (c) forming the nanofibers into the product.