Microfibers are very fine fibers manufactured by special processes. Developed to exhibit the drape and softness of silk in fabrics, microfibers are less than 0.00004 inches in diameter, about one-tenth the size of silk fibers. Technological inprovements have made it possible to produce smaller and smaller fibers, into the range of ultrafine fibers that have diameters of less than 0.000004 inches.
The first microfibers were made by using the traditional melt-spinning process of melting a polymer, such as nylon or polyester, and extruding it through very fine holes. The disadvantage of this direct spinning method was that the filament fibers were so fine they would break during the extrusion process or during subsequent conversion into yarns and fabrics. Consequently, special manufacturing techniques are used. The most common is to spin bicomponent fibers composed of two different polymer types (for example, nylon and polyester). The bicomponent fiber may have either a citrus or an islandsin-the-sea configuration. The citrus structure has wedge-shaped segments of one polymer held within a star-shaped core of a different polymer. In the islands-in-the-sea configuration, tiny "islands" of one polymer are dispersed in a "sea" of another polymer.
For both structures the bicomponent fiber as spun is thick enough to withstand the processing. After the bicomponent fibers are spun, they are made into yarns and woven or knitted into fabrics. After the fabric is formed, one of the polymer components is dissolved, leaving the other component as microfibers.
Because they are so fine, microfibers are flexible and bend easily, so that fabrics made from them are soft and drapable. In addition, microfiber fabrics are dense, because the small fibers are able to pack closely together. This gives the fabrics a degree of water repellency, since water cannot as easily penetrate the small pores between the fibers. These properties have dictated the types of apparel in which microfibers are used.
Uses for Microfibers
Polyester microfiber fabrics are often seen in all-weather coats, sports coats, and soft caps for men and women. Outerwear that has a comfortable feel and also repels moisture has made these microfiber garments popular. Further, the low moisture absorbency of the polyester fibers enhances the water repellency. Nylon microfiber fabrics on the other hand are used for underwear, lingerie, and hosiery. Nylon fibers have the stretch and recovery, as well as strength, often desired for these end uses. The very fine microfibers are soft and comfortable next to the skin, and nylon has higher moisture absorbency than polyester.
The aesthetic and functional advantages of microfibers are well recognized. They are, however, more expensive than their normal-size counterparts. This is because of the more complex manufacturing processes needed to produce them. Making the precursor bicomponent fibers requires specialized equipment, and dissolution of one component after the fabric is constructed is an additional finishing step that must be conducted under carefully controlled conditions.
Hongu, Tatsuya, and Glyn O. Phillips. New Fibres. Chichester, U.K: Ellis Horwood, 1990.