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Views: 13 Author: Site Editor Publish Time: 2023-12-12 Origin: Site
Introduction :
Wet spinning is a fiber production technique that has been used for over a century to produce a variety of synthetic and natural fibers, including rayon, nylon, acrylic, alginate fiber , cellulose fiber, viscose fibers, para-aramid fiber (Kevlar fiber), lyocell fiber: polyurethane fiber and spandex etc… . It involves the extrusion of a polymer solution or melt into a coagulation bath to form fibers. The resulting fibers can have a range of properties, such as high tensile strength, elasticity, and chemical resistance, making them suitable for various applications. FYI supplied different material wet spinning machine and dry jet wet spinning
1. Let me introduce about wet spinning process at first:
The wet spinning process typically consists of several steps. First, a polymer is dissolved in a suitable solvent to create a spinning solution. The solution may also contain additives, such as plasticizers or 2. stabilizers, to enhance the properties of the resulting fiber. The solution is then forced through a spinneret, which is a device with small holes or slits that determines the shape and size of the extruded fibers.
Next, the extruded filaments are passed through a coagulation bath, which contains a nonsolvent for the polymer. The nonsolvent causes the polymer to solidify and form fibers. The temperature, composition, and agitation of the coagulation bath can affect the final fiber properties.
After coagulation, the fibers are washed to remove any residual solvent or impurities. This step is crucial to ensure the purity and stability of the fibers. The washed fibers may undergo a drawing process, where they are stretched to align the polymer chains and improve the fiber strength and orientation. The fibers are then dried and subjected to finishing processes, such as heat setting, to further enhance their properties and make them ready for use.
2. Wet spinning process of alginate fiber
Alginate fiber is prepared by wet spinning. Wet spinning is to dissolve the fiber polymer in the appropriate solvent to get the spinning spinning solution. The spinning solution extruded through the spinneret and then enters the coagulation bath and precipitates out in the coagulation bath to form the fiber. The main steps are as follows:
1Dissolution: weigh a certain amount of sodium alginate powder and slowly add it to a certain amount of deionized water while stirring. Under the heating condition of 50℃, get the sodium alginate solution with 4% mass percentage.
2.De-foaming: In the laboratory, vacuum de-foaming method usually be used, the vacuum degree is controlled at 0.07-0.08Mpa, and the temperature is kept at 50℃. After de-foaming, spinning stock solution can be obtained.
3.Introduce the spinning solution into the materials tank, the temperature is maintained at 50℃, and the pressure is not higher than 0.3Mpa through compressed air.
4.Filtering: In order to remove the un-dissolved polymers and impurities in the spinning solution so as not to block the spinneret hole, a filter is set before spinneret.
5. Spinneret: The spinning solution is extruded from the spinneret holes by the metering pump
6.Solidification: CaCl2 solution with a temperature of 35℃ and a mass fraction of about 4% is used as solidification bath;
7. Washing: water bath temperature 30℃
8. Drafting: the proportion of drafting is controlled at 150%
9. 9.Drying: the drying temperature is controlled at 80-90℃
10. Winding: frequency conversion winding machine winding
Let we take 1 hour for example,
The filament length is 2.3m/min*60min=138m;
The solution volume=15ml/min*60min=900ml;
The alginate dry weight is 900ml*1.1g/ml*2%=19.8g;
Consider the moisture content 6% into account,
the filament weight is 19.8g*(1+6%)=21g
The multifilaments count =21/138*9000=1396Den
Per filament count=1396D/35=39.9D
This is a theoretical value, the actual value need to test the filament.
Secondly please do help basic calculation of flow rate for setup filament 3.5D – 5.0D
The same calculation as above steps, if the single filament is 5.0D, the winding speed is 2.3m/min, we also take 1 hour as sample,
Multifilamet count is 175D
The multifilaments weight is 2.68g;
The dry weight is 2.53g
Solution weight is 126.5g
Solution volume is 115ml
The pump flow is 115ml/60min=1.9ml/min
Note:
The dissolution process needs heat preservation. Can be put in a beaker (Cover the top of beaker with plastic wrap). Then place the beaker in an oven. It will take about 8 hours to dissolve (or can put it in the oven at night and use it the next morning);
It is better to have a magnetic stirrer to dissolve it;
The completely dissolved solution is transparent with viscosity. If you pick it with something, you won't see any particle or line (see below picture);
Take out the completely dissolved solution from the insulation equipment and pour into the raw material tank as soon as possible for spinning.
The specific details and parameters of the wet spinning process can vary depending on the polymer used and desired fiber properties. For example, the spinning solution may be cooled before extrusion to prevent premature coagulation, or the coagulation bath may contain additional components, such as surfactants, to modify the fiber surface properties.
There are several variations of the wet spinning process, including dry jet wet spinning and gel spinning. Dry jet wet spinning involves using compressed air to break up the extruded solution into fine jets before entering the coagulation bath. This process can help achieve finer and more uniform fibers. Gel spinning, on the other hand, involves spinning a polymer solution that has been partially gelled by cooling or chemical crosslinking. The resulting fibers have high strength and modulus due to the aligned polymer chains in the gel.
Conclusion:
Wet spinning is a versatile fiber production technique that has enabled the development of many synthetic and natural fibers with unique properties. The process involves dissolving a polymer in a suitable solvent, extruding the solution through a spinneret, coagulating the filaments in a nonsolvent bath, and finishing the resulting fibers. Different variations of the process can be used to modify the fiber properties and achieve specific performance characteristics. More detailed please visit our website
