Sunday, January 6, 2013

Textile Terms, Important Textile term and definitions

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Fibres 
Fibre is one of the most important textile terms. Fibers are the smallest part of the fabric. They are fine, hair-like substances, categorized as either natural or manufactured. Cotton, which grows on a plant, and wool, which is shorn from a sheep, are two examples of natural fibers. Manufactured fibers are created from chemicals and include acrylic, nylon, and polyester. They are produced by chemical companies, such as E.I. DuPont de Nemours & Company and Hoechst Celanese Corporation. 


Yarns 

The term yarn means the raw material of fabric. Most textile materials contain yarns, which are continuous thread-like strands composed of fibers that have been twisted together. (Felt is an example of a material made directly from fibers but containing no yarns). There are various types of yarn, from flat and dull to slubby and lustrous. Each one could be made from different fibers. 


Fabrics

The definition of fabric is very simple. Most fabrics are made from yarns and are either woven or knitted. The companies that make fabric are called mills; Springs Industries and Milliken & Company are two of the largest mills. The range of fabric types and weights is tremendous, fulfilling a variety of consumer demands. 

Dyeing and Printing 
Color is usually applied to the woven or knitted fabric by either Dyeing or Printing. The term dyeing is the process for imparting a solid color to textiles (blue, green, red, etc.). The term printing is the process of imparting designs to textiles (dots, floral, stripes, etc.). The purpose is to make the fabric more appealing. These operations are performed in dye plants or pint plants, and the companies are called dye houses or pint houses. 


Finishing

Most fabrics need additional treatments termed as finishes before they can be used. For example, special chemicals are used to make a fabric water-repellent and suitable for a raincoat. A special brushing machine is required to make the fuzzy surface on flannel fabrics. The processes are done in finishing plants whose facilities are most often part of dye plants or print plants. After finished fabric has been produced, it is usually used by other manufacturers to make such items as blouses, draperies, tents, or automobile tires. A particular fabric might be used for several different articles, such as a dress, a shirt, and curtains Frequently, the same fabric that is shipped to the apparel or interior furnishings manufacturer is also sold to a retail store for direct sale to home sewers. 


Automation and Computer Use 

As with practically every other endeavor of our lives, computers and electronic technologies have had a tremendous impact on textile-related industries and businesses. Computerization has made a difference in design, decision-making, communication, and process control in manufacturing. Feedback on consumer preferences and product sales is readily available to fiber and fabric producers, apparel manufacturers, dyers, and finishers. The computer has become a routine tool for apparel and interior designers and for product developers; and control of manufacturing processes is increasingly a job for computer programmers. 

The textile and apparel industries have formed an organization called the Textile/ Clothing Technology Corporation or (TC) 2. The purpose of TC2 is to conduct research about applications of electronic technology in the textile and apparel industries and to educate executives, engineers, technologists, and educators about automated systems, their potential, and their use. (TC) 2 is funded jointly, largely by matching grants, by the industry and the federal government. 


Computer-Aided Design (CAD)

Computer-aided design (CAD) in textiles is applied to the design of yarns and fabrics and to coloration. In those firms that are vertically integrated, CAD may also be applied to apparel design and manufacture. Programs allow the textile designer to develop and modify designs interactively, speeding up the process and providing electronic links to production. 

Recent techniques in three-dimensional (3-D) imaging enable simulation of the actual fabric structure and texture on screen and advances in color printing allow better reproduction of the design on paper or other media. Designs can be scanned into the system and then modified or redesigned. CAD applications for knitted fabrics and garments have advanced rapidly. A variety of CAD systems that interface design and construction in the production of woven fabrics and knitted goods are currently available and in use. New technologies have also been developed to predict the drape of fabric on 3-D moving figures, integrating the fabric and apparel design stages. This involves mathematical modeling using fabric behavioral properties. The fabric’s physical characteristics are separated from the surface design so that different types of motion can be applied to any design (Gray 1994; Gray 1998). (See Figure 1.10.) This, along with the textile design capabilities described above, allows merchandisers to create “virtual samples” for customers (Ross 1998). Computer figures are also used in 3-D scanning, a development in CAD, that is moving the apparel manufacturing customization, which is the mass production of custom garments. Women’s jeans produced through such a process were first marketed in November 1994 (Rifkin 1994).
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Saturday, January 5, 2013

Textile Finishing; Light Reftectant and Light Resistant Finishing

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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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Friday, January 4, 2013

Textile Finishing; Flame Resistance Temperature Regulating Heat Reflectant Finishing

Flame Resistance finishing:
Flame resistance finishing is modern process of finishing. The terminology employed in a discussion of flame resistance finishing can be confusing. The following definitions and descriptions are currently accepted, although usage may vary, particularly from country to country.

1. Flame resistance finishing is defined by American Society for Testing and Materials (ASTM) (1998, 23) as “the property of a material whereby flaming combustion is prevented, terminated, or inhibited following application of a flaming or non-flaming source of ignition, with or without the subsequent removal. of the ignition source.” The material that is flame resistant may be a polymer, fiber, or fabric.

2. Use of the terms flame retardant and self-extinguishing is discouraged (ASTM 1998, 23, 40). Flame-retardant treated and flame-retardant treatment are, however, acceptable terms and flame retardant is used in other countries. ASTM does not approve the use of the term self-extinguishing to describe a textile product because it is meaningful only when applied to specific circumstances.

3. A thermally stable material (fiber or polymer) is one that has a high decomposition temperature and is thus inherently flame resistant because of chemical structure (rather than through the presence of added flame-retardant treatments) (Clark and Tesoro 1974).)

Temperature Regulating Finishes
Temperature-regulating fabrics are sensitive to the surrounding temperature or to body heat. Finishes that provide this adaptation include substances called phase change materials (PCMs) (Lennox-Kerr 1998). These substances change from solid to liquid or liquid to solid depending on the temperature. The example we are probably most familiar with is ice changing to water when the temperature rises and then changing back to ice again when cooled. Ice absorbs heat to melt and water gives off heat when it becomes solid. PCMs work the same way but are selected to undergo this phase change around normal skin temperature.

One such finish is polyethylene glycol (PEG), which is applied to fabrics along with a methylol agent such as DMDHEU. The result is a network polymer that is insolubilized on the surface of the fibers. The polymer absorbs and holds heat energy at high temperature, and then releases the stored energy under cooler conditions. The finish is durable to wear and laundering, because it is cross linked on the fabric.

Not only do these finishes help to warm or cool the body, but they also increase the moisture absorbency of fabrics, thereby further enhancing comfort. Other improved properties are resistance to static, wrinkling, abrasion, pilling, and soil. The PEG finish has been used on T-shirts, underwear, socks, activewear, and biomedical products.

In another form, PCMs have been applied to fabrics as microcapsules in coatings, used in nonwoven bonding materials, or included in spinning solutions of manufactured fibers. Outlast Technologies, Inc. produces the microcapsules. Acordis Fibers has produced a version of their Courtelle acrylic fibers with the PCM embedded in them. The fabrics made with these fibers are targeted for outdoor apparel, particularly for cold climates. PCM-containing textile fabrics are expensive because the encapsulation process is technology intensive.

Heat Reflectant Finishes
An increased level of insulation can be provided in garments and draperies by the addition of heat-reflectant finishes. Most of these products are treated with a spray coating of metal and resinous substances. The heat-reflectant material is sprayed onto the surface of a closely woven fabric. The finish is designed to keep heat either on one side or the other side of the fabric. The finish is effective only with radiated heat.

Lining fabrics are usually constructed so that the finish is applied to the inside of the fabric. The finish reflects the body heat back toward the wearer, thus providing added warmth. In protective clothing to be worn under hot conditions, the finish is worn to the outside to deflect heat away from the body.

Draperies may also be treated to provide greater insulation for homes. Treated draperies placed inside windows may serve to keep heat inside the home or to reflect heat outward, preventing it from warming the house. Some of the processes designed to produce heat reflectance use aluminum in the finish, because it provides excellent reflectancy. A variant of this principle is utilized in fabrics coated or laminated with a thin layer of aluminum, foams, resins, or synthetic rubber.