In this process, a polymer is melted and heated to a suitable viscosity for fiber production. The melted polymer is pushed through a spinneret, which is a type of die consisting of several small holes. Each hole produces an individual fiber, and the number of holes on a spinneret defines the number of fibers in the yarn. The melted polymer fibers then passes through a cooling region and the fibers are combined to form a yarn and a spinfinish is applied. The yarn is then drawn using several godets rolls with very good speed and temperature control to orient the molecules in the fibers and eliminate voids, making the yarn stronger.
Melt spinning is the fastest fiber production system available in current technology. Therefore, if the polymer is thermoplastic, then melt spinning should be used for higher productivity. Most of the manmade fibers, such as polyester, polypropylene, nylon and PGA, are produced using melt spinning.
Melt spinning technology is very advanced and parameter control of the process is very good. It is possible to produced shaped fibers such as circular, triangular, and hollow fibers using melt spinning. Production of biocomponent and tricomponent fibers is also possible using this process.
Secant Group has state-of-the-art, versatile melt spinning equipment with very sensitive speed and temperature controls along with several drafting zones. Our design, development, and production capabilities include:
- High tenacity polyester (>9g/den) fibers
- A variety of yarns from 10 denier to 1000 denier, with 8 to 136 filaments
- Shaped fibers to maximize the yarn performance for any device property need
- Production of small yarn batches as low as one pound
- Biocomponent (including islands-in-the-sea fiber) and tricomponent fibers using different polymers
Wet Spinning and Dry-Jet Wet Spinning
These processes are used for thermoset polymers such as acrylic, liquid crystalline polymers (Kevlar and Nomex), and polyurethane. In wet spinning, the polymer is dissolved in a solvent at a target concentration to make a polymer solution with the desired viscosity. This polymer solution is then extruded under heat (if needed) and pressure into a liquid coagulation bath. Then fibers are combined as yarn and the yarn is drawn, with very good controls, to orient the molecules in the fibers so that it becomes stronger.
Dry-jet spinning is very similar to wet spinning. However, for some polymers, putting a spinneret into the coagulation bath does not work. Therefore, the dissolved polymer is feed out of the spinneret on an air gap to drive off the solvent and then goes into a coagulation bath to be solidified.
The production speed for both is very low compared to the melt spinning process. The advantage of these processes is that the production of fiber from mixtures of polymers and the incorporation of additives is easier. Another advantage is that fiber production is possible using very low amounts of polymers, as low as 20 grams. This is very important especially for newly discovered polymers that have only been produced under lab conditions. Therefore, wet spinning and dry-jet wet spinning lines are more appropriate for research use.
Secant Group has versatile wet/dry-jet spinning equipment with three coagulation baths, a dryer and heater. Therefore, either process could be applied to fiber design, development, and production. We can produce very small amounts of fibers and yarns with different deniers and number of fibers in the yarn. We also have the expertise to produce specialty polymers and copolymers for most desired application.