Microfiber or microfibre is synthetic fiber finer than one denier or decitex/thread. This is smaller than the diameter of a strand of silk (which is approximately one denier), which is itself about 1/5 the diameter of a human hair. The most common types of microfibers are made from polyesters, polyamides (e.g., nylon, Kevlar, Nomex, trogamide), or a conjugation of polyester, polyamide, and polypropylene (Prolen). Microfiber is used to make mats, knits, and weaves for apparel, upholstery, industrial filters, and cleaning products. The shape, size, and combinations of synthetic fibers are selected for specific characteristics, including softness, toughness, absorption, water repellency, electrostatics, and filtering capabilities.
Microfiber that is made from petrochemicals includes polyester and nylon which are not biodegradable. However, microfiber made from polypropylene can be recyclable. Microfiber products may also have the potential of entering the oceanic water supply and food chain similar to other microplastics. Synthetic clothing made of microfibers that are washed can release materials and travel to local wastewater treatment plants, contributing to plastic pollution in water.
Production of ultra-fine fibers (finer than 0.7 denier) dates back to the late 1950s, using melt-blown spinning and flash spinning techniques. However, only fine staples of random length could be manufactured and very few applications could be found. Experiments to produce ultra-fine fibers of a continuous filament type were made subsequently, the most promising of which were run in Japan during the 1960s by Dr. Miyoshi Okamoto, a scientist at Toray Industries. Okamoto's discoveries, together with those of Dr. Toyohiko Hikota, resulted in many industrial applications. Among these was Ultrasuede, one of the first successful synthetic microfibers, which found its way onto the market in the 1970s. Microfiber's use in the textile industry then expanded. Microfibers were first publicized in the early 1990s in Sweden and saw success as a product in Europe over the course of the decade.
Microfiber fabric is often used for athletic wear, such as cycling jerseys, because the microfiber material wicks moisture (perspiration) away from the body, keeping the wearer cool and dry. Microfiber is also very elastic, making it suitable for undergarments. However, the US Marine Corps banned synthetic fabrics for wear with uniforms while deployed to combat environments in 2006, because of instances where Marines' undergarments were melting under extreme heat caused by IED (improvised explosive device) blasts, causing more damage to the skin. They released a "fit for duty" version authorized earlier that same year.
Microfiber can be used to make tough, very soft-to-the-touch materials for general clothing use, often used in skirts and jackets. Microfiber fabric can also be used for making bathrobes, jackets, swim trunks, and other clothing that can be worn for aquatic activities such as swimming. Microfiber can be made into Ultrasuede, an animal-free imitation suede leather-like product that is cheaper and easier to clean and sew than natural suede leather.
Microfiber is used to make many accessories that traditionally have been made from leather: wallets, handbags, backpacks, book covers, shoes, cell phone cases, and coin purses. Microfiber fabric is lightweight, durable, and somewhat water repellent, so it makes a good substitute.
Another advantage of fabric (compared to leather) is that fabric can be coated with various finishes or can be treated with antibacterial chemicals. Fabric can also be printed with various designs, embroidered with colored thread, or heat-embossed to create interesting textures.
Textiles for cleaning
In cleaning products, microfiber can be 100% polyester, or a blend of polyester and polyamide (nylon). It can be both a woven product or a non woven product, the latter most often used in limited use or disposable cloths. In the highest-quality fabrics for cleaning applications, the fiber is split during the manufacturing process to produce multi-stranded fibres. A cross section of the split microfiber fabric under high magnification would look like an asterisk.
The split fibres and the size of the individual filaments make the cloths more effective than other fabrics for cleaning purposes. The structure traps and retains the dirt and also absorbs liquids. Unlike cotton, microfiber leaves no lint, the exception being some micro suede blends, where the surface is mechanically processed to produce a soft plush feel.
For microfiber to be most effective as a cleaning product, especially for water-soluble soils and waxes, it should be a split microfiber. Non-split microfiber is little more than a very soft cloth. The main exception is for cloths used for facial cleansing and for the removal of skin oils, (sebum), sunscreens, and mosquito repellents from optical surfaces such as cameras, phones and eyeglasses where in higher-end proprietary woven, 100% polyester cloths using 2 µm filaments, will absorb these types of oils without smearing.
Microfiber that is used in non-sports-related clothing, furniture, and other applications isn't split because it isn't designed to be absorbent, just soft. When buying, microfiber may not be labelled to designate whether it is split. One way to determine what microfiber it is to run the cloth over the palm of the hand. A split microfiber will cling to imperfections of the skin and can be either heard or felt. Another way is to pour a small amount of water on a hard flat surface and try to push the water with the microfiber. If the water is pushed rather than being absorbed, it's not split microfiber.
Microfiber can be electrostatically charged for special purposes like filtration.
Microfiber products used for consumer cleaning are generally constructed from split conjugated fibers of polyester and polyamide. Microfiber used for commercial cleaning products also includes many products constructed of 100% polyester microfiber. Fabrics made with microfibers are exceptionally soft and hold their shape well. When high-quality microfiber is combined with the right knitting process, it creates an extremely effective cleaning material. This material can hold up to eight times its weight in water. Microfiber products have exceptional ability to absorb oils, and are not hard enough to scratch even paintwork unless they have retained grit or hard particles from previous use.
Microfiber is widely used by car detailers to handle tasks such as removing wax from paintwork, quick detailing, cleaning interior, cleaning glass, and drying. Because of their fine fibers which leave no lint or dust, microfiber towels are used by car detailers and enthusiasts in a similar manner to a chamois leather.
Microfiber is used in many professional cleaning applications, for example in mops and cleaning cloths. Although microfiber mops cost more than non-microfiber mops, they may be more economical because they last longer and require less effort to use.
Microfiber textiles designed for cleaning clean on a microscopic scale. According to tests using microfiber materials to clean a surface leads to reducing the number of bacteria by 99%, whereas a conventional cleaning material reduces this number only by 33%. Microfiber cleaning tools also absorb fat and grease and their electrostatic properties give them a high dust-attracting power.
Microfiber cloths are used to clean photographic lenses as they absorb oily matter without being abrasive or leaving a residue, and are sold by major manufacturers such as Sinar, Nikon and Canon. Small microfiber cleaning cloths are commonly sold for cleaning computer screens and eyeglasses.
Microfiber is unsuitable for some cleaning applications as it accumulates dust, debris, and particles. Sensitive surfaces (such as all high-tech coated surfaces e.g. CRT, LCD and plasma screens) can easily be damaged by a microfiber cloth if it has picked up grit or other abrasive particles during use. One way to minimize the risk of damage to flat surfaces is to use a flat, non-rugged microfiber cloth, as these tend to be less prone to retaining grit.
Rags made of microfiber must only be washed in regular washing detergent, not oily, self-softening, soap-based detergents. Fabric softener must not be used. The oils in the softener and self-softening detergents will clog up the fibers and make them less effective until the oils are washed out.
Microfiber materials such as PrimaLoft are used for thermal insulation as a replacement for down feather insulation in sleeping bags and outdoor equipment, because of their better retention of heat when damp or wet.
With microfiber basketballs already popular worldwide and in FIBA, the NBA proposed the use of a microfiber ball for the 2006–07 season. The ball, which is manufactured by Spalding, does not require a "break-in" period of use as leather balls do and has the ability to absorb water and oils, meaning that sweat from players touching the ball is better absorbed, making the ball less slippery. Over the course of the season, the league received many complaints from players who found that the ball bounced differently from leather balls, and that it left cuts on their hands. On January 1, 2007, the league scrapped the use of all microfiber balls and returned to leather basketballs.
Microfibers used in tablecloths, furniture, and car interiors are designed to repel wetting and consequently are difficult to stain. Microfiber tablecloths will bead liquors until they are removed and are sometimes advertised showing red wine on a white tablecloth that wipes clean with a paper towel. This and the ability to mimic suede economically are common selling points for microfiber upholstery fabrics (e.g., for couches).
Microfibers are used in towels especially those to be used at swimming pools as even a small towel dries the body quickly. They dry quickly and are less prone than cotton towels to become stale if not dried immediately. Microfiber towels need to be soaked in water and pressed before use, as they would otherwise repel water as microfiber tablecloths do.
Microfiber is also used for other applications such as making menstrual pads, cloth diaper inserts, body scrubbers, face mitts, whiteboard cleaners, and various goods that need to absorb water and/or attract small particles.
Environmental and safety issues
Microfiber textiles tend to be flammable if manufactured from hydrocarbons (polyester) or carbohydrates (cellulose) and emit toxic gases when burning, more so if aromatic (PET, PS, ABS) or treated with halogenated flame retarders and aromatic dyes. Their polyester and nylon stock are made from petrochemicals, which are not a renewable resource and are not biodegradable. However, if made out of polypropylene, they are recyclable (Prolen).
For most cleaning applications they are designed for repeated use rather than being discarded after use. An exception to this is the precise cleaning of optical components where a wet cloth is drawn once across the object and must not be used again as the debris collected and now embedded in the cloth may scratch the optical surface.
There are environmental concerns about this product entering the oceanic food chain similar to other microplastics. A study by the clothing brand Patagonia and University of California, Santa Barbara, found that when synthetic jackets made of microfibers are washed, on average 1.7 grams (0.060 oz) of microfibers are released from the washing machine. These microfibers then travel to local wastewater treatment plants, where up to 40% of them enter into rivers, lakes, and oceans where they contribute to the overall plastic pollution. Microfibers account for 85% of man-made debris found on shorelines worldwide. 
However, no pesticides are used for producing synthetic fibres (in comparison to cotton). If these products are made of polypropylene yarn, the yarn is dope-dyed; i.e. no water is used for dyeing (as with cotton, where thousands of liters of water become contaminated).
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