Saturday, January 5, 2013

Textile Finishing; Light Reftectant and Light Resistant Finishing

Textile finishing is complex procedure. There are two types of fabric finishing. Light-Reftectant Finishing and Light-Resistant Finishing are one kind of chemical finishing. Those fabric finishing process are used to make textiles lightproof for particular end use. Some of the chemical change their form in presence light. In that case the chemical must preserve in light protected area. We can easily produce ultraviolet protected fabric using the light reflectant and resistant finishes. Ultraviolet protection is now being built into fibers and fabrics. 

Light-Reftectant Finishes 

Light-reflectant finishes are created by the application of microscopic reflective beads to the surface of a fabric. The increased number of persons who jog or ride bicycles after dark is probably responsible for the application of this finish to a variety of garments for sports and to other items such as backpacks. A reflective finish called Scotchlite is produced by the 3M Company. The manufacturer notes that the finish does not alter the color or appearance of the garment by day, but after dark the fabric “lights up” when directly in the path of the lights of an oncoming vehicle. 

Light-Resistant Finishes

Many textile fabrics are deteriorated by exposure to sunlight, so attempts have been made to protect fabrics from light damage. Of all the types of rays in the sun’s spectrum, ultraviolet rays are the most destructive of fibers. Although antilight finishes have yet to be perfected, those that are being tried either coat the fabric or impregnate the fibers with materials that absorb ultraviolet rays but are not themselves damaged by or removed by exposure to these rays. Such finishes are particularly important in olefin fabrics, which are degraded by sunlight unless ultraviolet stabilizers are added. Such additives to olefin fibers are permanent and are not lost during usage. 

Synthetics that have been delustered with titanium dioxide are especially subject to damage from sunlight. This chemical apparently accelerates damage to the fiber and fading of dyes. The addition of certain chemical salts to the melt solution before spinning can ameliorate this problem. The relationship between exposure to the ultraviolet light of the sun and skin cancer is well known. Many people assume that fabrics prevent exposure to any part of the body that is covered; however, research shows that fabrics do allow passage of ultraviolet light. Knitted fabrics, which usually have a more open structure, generally allow more ultraviolet light through than woven fabrics; lightweight summer fabrics allow more ultraviolet light to reach the skin than heavier fabrics with more opaque yarns. Ultraviolet protection is now being built into fibers and fabrics. Most of the techniques are proprietary processes, so details of how the protection is provided are limited. Kuraray, a Japanese firm, produces Esmo, a polyester staple fiber to which powdered ceramics have been added to absorb and reflect ultraviolet rays. A similar fiber called Aloft is produced by the Japanese firm Toray, and other Japanese firms produce fabrics that are given special protective finishes Australian researchers have developed a chemical finish called Rayosun that is said to be washfast, colorfast, and lightfast. The finishing material contains a “two part molecule,” one part of which absorbs ultraviolet rays while the other part reacts with the fabric, thereby making the finish durable (Sun-proof clothing 1993, 72).

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