Melt Spinning Process:
Melt spinning is the simplest extrusion process in that no addition and subsequent removal of solvent is required. It is the most popular and economic method for polymer fiber manufacturing at industrial scales. In melt spinning, the fiber-forming substance is melted for extrusion through the spinneret and then directly solidified by cooling. In this spinning process, the spinning compound is spun into a cold-air quench duct. Because in this process no solvents are released, the recycling of by-products is not necessary.
Melt spinning uses the heat to melt the polymer to a viscosity suitable for the extrusion through the spinneret. As the name indicates the chips of fibers are melted and extruded through the spinneret to obtain the fibers. It is used for the polymers that are not decomposed or degraded by temperatures necessary for extrusion are melted and then pumped through a spinneret in an air chamber. The extruded stream cool and solidify into continuous filaments and are then drawn out of the chamber twisted and/or processed further and subsequently wound onto spools. This method of spinning is suitable for producing polyamide (nylon), polyethylene terephthalate (polyester) and polypropylene fibers, all of which are widely used commodity textiles.
Fig: Schematic diagram of the melt spinning process
Melt spun fibers can be extruded from the spinneret in different cross-sectional shapes (round, trilobal, pentagonal, octagonal, and others). Trilobal-shaped fibers reflect more light and give an attractive sparkle to textiles.
Pentagonal-shaped and hollow fibers, when used in carpet, show less soil and dirt. Octagonal-shaped fibers offer glitter-free effects. Hollow fibers trap air, creating insulation and provide loft characteristics equal to, or better than, down.
Requirements for Melt Spinning:
The polymer should not be volatile
The polymer should not decompose in the molten state and the melting point.
Polymer should be 30 degree centigrade less than its decomposition temperature.
Special Feature of Melt Spinning:
High production (SPG. Speed 1000-2000 m/min)
Hazard, Non Toxic
No environment pollution.
No solvent required .
Heat of spg high.
Fiber Characterizations:
Different characterization methods were performed to study the resulting fiber properties, including microstructures, thermal properties, mechanical properties, rheological properties, molecular orientation and crystallization behavior.
Fiber Which Processed by Melt Spinning:
Polyester, Nylon, Olefin, Polypropylene, saran, and sulfur etc. are produced via melt spinning process.
Advantages of Melt Spinning:
Can be used for both staple and continuous filament.
Direct and simple process.
No environment pollution.
High production speed (2500-3000) ft/min.
Low investment cost.
Disadvantage of Melt Spinning:
The limits of the melt spinning process need to be considered for developing filaments with extremely low or high diameters. For coarser filaments, the highest possible mass throughput rate per hole of the spinneret is required while maintaining the lowest possible take-up velocity. Filaments with low diameters after drawing can be produced by keeping the minimum possible throughput rate, maximum possible take-up velocity and a high draw ratio. Besides,
Required more proper maintained of machine.
Heat of input is high.
Melt spinning is among the most versatile and commonly used methods for producing polymeric filaments. The fundamentals, manufacturing, advantages and disadvantages/limitations of melt spinning are described in this article.
Founder & Editor of Textile Learner. He is a Textile Consultant, Blogger & Entrepreneur. He is working as a textile consultant in several local and international companies. He is also a contributor of Wikipedia.
