Continuous Aramid Fiber Recycling via Sulfuric Acid Spin Dope
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Solution Overview
Problem
Existing recycling processes for aramid fibers are inefficient, economically unviable, and limited in their ability to handle a broad range of aramid materials, resulting in low-quality recycled fibers unsuitable for diverse applications.
Innovation Solution
A continuous process involving the combination of aramid fibrous material with sulfuric acid to create a spin dope, which is then processed into high-quality continuous aramid fibers using a dry-jet wet spinning method, allowing for the recycling of various aramid materials and producing fibers with mechanical properties comparable to virgin fibers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If discontinuous recycling processes are used with elaborate pre-treatment steps, then aramid fibers can be recycled, but the process complexity and time consumption increase significantly
Solution Approach 1:
The patent employs a continuous recycling process where aramid fibrous material is continuously fed through the system, dissolved in sulfuric acid, extruded through a spinneret, and collected as continuous fibers without interruption. This eliminates the need for separate pre-treatment, dissolution, and spinning stages that characterize discontinuous processes, thereby reducing overall process complexity while maintaining recycling capability.
Solution Approach 2:
The recycling process is divided into distinct functional zones: a feeding zone where aramid material is introduced, a dissolution zone where sulfuric acid breaks down the aramid into spin dope, an extrusion zone where the spin dope is forced through a spinneret, and a collection zone where continuous fibers are formed. This segmentation allows each zone to be optimized independently while working together in a continuous flow, reducing overall process complexity.
2Adaptability or versatility
If traditional pulp recycling method is used, then aramid short-cut can be converted to pulp, but the recycled fibers are limited to small percentages in composite materials and cannot be used in diverse applications
Solution Approach 1:
The patent changes the physical and chemical parameters of the recycling process by using sulfuric acid dissolution followed by controlled extrusion and phase separation. This produces continuous fibers with controlled molecular orientation and crystallinity, achieving manufacturing precision comparable to virgin fibers. The resulting fibers can be used in diverse applications including high-performance composites, textiles, and reinforcement materials, vastly expanding adaptability beyond the limited pulp application range.
3Productivity
If existing recycling processes are used, then some aramid materials can be recycled, but the process is not efficient and economical
Solution Approach 1:
The continuous process allows aramid fibrous material to be continuously dissolved, extruded, and converted into recycled continuous fibers without interruption. This eliminates the repeated heating, cooling, and material handling cycles inherent in discontinuous processes, significantly improving productivity while reducing energy consumption through sustained operational conditions and minimized thermal cycling.
4Reliability
If elaborate pre-treatment steps including unwinding, drying, soaking, and washing are performed, then continuous aramid yarn can be dissolved, but the process time and operational complexity increase
Solution Approach 1:
The patent extracts and eliminates the time-consuming pre-treatment steps (unwinding, drying, soaking, washing) by directly feeding aramid fibrous material into the dissolution zone where sulfuric acid immediately begins breaking down the aramid structure. The continuous nature of the process allows the material to be continuously dissolved and converted without interruption, significantly reducing process time while maintaining dissolution effectiveness through optimized acid concentration and residence time in the dissolution zone.
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 enables the production of high-quality continuous aramid fibers suitable for a wide range of applications, overcoming the limitations of existing methods by providing efficient and economical recycling of diverse aramid materials.
Implementation Method 1
combining aramid fibrous material comprising non-continuous aramid fibers with sulfuric acid to obtain a spin dope comprising aramid
Implementation Method 2
processing the spin dope comprising aramid into a continuous aramid fiber using a dry-jet wet spinning method
Data Source
Figure 1
AI summary
The application pertains to a continuous process for the recycling of aramid fiber comprising the following steps: - combining aramid fibrous material comprising non-continuous aramid fibers with sulfuric acid to obtain a spin dope comprising aramid, and - processing the spin dope comprising aramid into a continuous aramid fiber. The invention also pertains to a continuous aramid fiber, preferably obtainable by said process, and to a multifilament yarn comprising said continuous aramid fiber.