Sunday, January 6, 2013

Manufactured Fibres or Textile Fiber manufacturing

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The producer of natural fibres and the producer of manufactured fibres are engaged in two very different businesses. The farmer who raises cotton, the rancher who herds sheep or the grower of silkworms is trying to produce a maximum quantity of fibre from animal or vegetable sources. The grower may attempt to improve the quality of the seeds or breeding stock but is limited in production by natural factors. If the demand for the product increases or decreases, the grower cannot, like the manufactured fibre producer, simply increase or decrease the short-term supply of fibre.

Manufactured Fibres
The term-manufactured fibre describes a fibre produced commercially through regeneration from natural materials or synthesized from chemicals. Trade associations in the manufactured fibres industry may be industry wide or specific to particular fibres. The American Fibre Manufacturers Association, Inc. (AFMA) is the trade organization for the manufactured fibres industry, conducting many of the same kinds of promotional activities as described for the natural fibres associations.

AFMA always uses generic fibre names-such as polyester, nylon, rayon, and so on-in printed materials, while its individual fibre producing members concentrate on their trademarked fibre names, such as DuPont’s Dacron@ (polyester) or Wellman’s Fortrel@ (polyester). Producers of particular fibres may also join together to form fibre-specific trade associations. The Acrylic Council, the Polyester Council, and the American Polyolefin Association are examples of fibre-focused trade associations.

Production in the manufactured fibres industry differs from the production of natural fibres in a number of ways. While the manufactured fibres industry must depend on available supplies of the raw materials from which fibres are made, this industry is not dependent on natural forces that regulate the supply of fibre. A great many manufactured fibres are made from materials derived from petroleum, and therefore supplies and costs of raw materials may be affected by changes in the price of oil. Manufacturers can regulate production according to supply and demand. Manufacturers can also help to create demand for increased quantities of fibre products through advertising and other publicity.

Many manufactured fibre producers and firms are, or were originally, chemical companies. The fibre manufacturer generally sells the fibres produced to a firm that will make yarns and/or fabrics. These fibres may be sold as unbranded products or commodities. When fibres are sold in this way, the purchaser has no obligation to the fibre manufacturer to produce a product of any specific quality. Products must meet no minimum standards. In short, the buyers can do whatever they wish with the fibres they have purchased. Other fibres may be sold as trademarked fibres. The manufacturer owns the trademark, which is denoted by placing either the symbol @ or TM after the trademarked name. Trademarked names are always capitalized-for example, Micrell@ polyester. The owner of a trademark can bring court action to prevent unauthorized use of the trademark.

When the fibre manufacturer’s trademarked name is carried by the finished product, the fibre manufacturer has some control over the quality of the fabric, although it is still possible that a poorly made garment could be constructed from the fabric. One advantage to the fabric and garment manufacturers of buying a trademarked fibre is that they can capitalize on the publicity and promotional materials distributed by the fibre manufacturer. Licensed trademarked fibres are sold only to those manufacturers whose fabrics meet the standards established by the fibre manufacturer. Standards may be set in regard to the construction of fabrics, the manufacture of apparel or other products, and, in blends or combinations of two or more fibres, the appropriate proportion of fibres to be combined. As an alternative to trade marking, some fibre companies assign certification mark names to yarns or fabrics made from their fibres. Such designations require that the items identified with the certification mark meet criteria established by the fibre manufacturer.

Not only do the fabric and garment manufacturers benefit from customer familiarity with the brand name of the fibre, but the fibre manufacturer often shares the costs of advertising or mounts intensive publicity campaigns to promote the fabric, the final product, and even retail outlets where the products are sold.

The interest of manufactured fibre producers in their products does not end when the fibre is sold. Because techniques for spinning and fabricating manufactured fibres may not be uniform for all fibres, the fibre producer provides technical assistance to the fabric manufacturer. Technical bulletins are published that recommend the most effective ways of processing fibres. Consultants from the fibre companies provide information about new developments in textile machinery and finishing. Research and development in fibre-producing companies is often focused on more effective ways of handling manufactured fibres during fabrication.

Fibre producers assist manufacturers of fabrics, garments, or other products to locate sources of yarns and fabrics. The marketing department of a fibre-producing company also maintains a library of fabrics that can be used by manufacturers and their designers.

A wide variety of other services is offered to the direct customers of the fibre companies and to the general public. Exhibits of current products are presented, often at trade and professional meetings. Educational materials for schools, retailers, and consumers are prepared and distributed. Retail stores may be assisted in promoting trademarked products through fashion shows, publicity materials, or cooperative advertising in which the fibre producer pays some part of the advertising costs. Fashion consultants may be available to assist the designers of fabrics, clothes, and furnishings.

Many of these activities are part of an organized advertising and public relations program. In addition to the services offered that result indirectly in publicity and goodwill for the company, direct advertising is also utilized. Besides advertising cooperatively with manufactures of retail products and retail stores, fibre companies also advertise in publications ranging from those for the trade to general magazines. Research and development (often abbreviated as R & D) is an important function in most large textile fibre companies.

Researchers are constantly looking for new fibres, fibre modifications, and improvements in processing at all steps of manufacture. The whole synthetic fibres industry might be said to have grown out of the research and development program at the chemical company Dupont, for it was in this program that W. H. Caruthers first synthesized nylon.
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Industrial Textiles; The Major Textile Production Segments

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Industrial Textiles 
Most consumers are not aware of the segment of the textile industry known as industrial textiles, even though they encounter these products every day. Industrial textiles is the most commonly used name for textile applications in agriculture, air and water filtration, architecture, automobiles, banners and flags, casual furniture, environmental protection, earth stabilization, medical products, recreational products, and transportation vehicles. Apparel items in this category are those in which performance is paramount: clean room garments, protective gloves and clothing for industry and farming, industry garments that don’t develop electrostatic charges (World of Industrial Fabrics n.d.) 

Other descriptive terms applied to this segment of the industry are industrial fabrics, technical textiles, engineered fabrics, and technical fabrics. Industrial textiles may be woven, knitted, or nonwoven, often of manufactured fibers. Fashion is not a factor in industrial textiles, but instead such functional characteristics as strength, stability, chemical resistance, and weight are likely to be important. Examples of industrial textiles range from small products such as filters and auto safety belts to enormous structures such as roofs, tents, and storage tanks. Roofs and other building structures encompass the field of textile architecture, a growing area of interest that combines engineering and art design. Consumers of industrial products include the construction, mining, sanitation, and transportation industries; medicine; and the military. 

The industrial fabric segment of the textile field has grown rapidly in recent years. Some of the more dramatic examples of progress in textile technology have come in this area, particularly fiber-reinforced composites for the aerospace industry and geotextiles. Geotextiles are textiles used in soil and soil-based structures such as roads, dams, and erosion-control products. 

The Major Textile Production Segments 
The textile industry is segmented into three large groupings: Apparel, the textiles used in clothing; interior furnishings (also called home fashions) the textiles used in furniture, bath, kitchen and bed; and industrial, the textiles used in such items as luggage, flags, boat sails, gauze bandages, dust filters, and so on. The market is divided into approximately 40 percent apparel, 40 percent interior furnishings, and 20 percent industrial and miscellaneous consumer-type products. 

The textile industry uses many different raw materials and many steps in the process of manufacturing a finished textile material. Each segment in the pipeline is not only involved with production, but also with buying the product of a previous producer. Thus, the entire process from fiber to consumer (or other ultimate buyer) involves the coordinated activities of many firms and many individuals within each firm. The following sections describe the major production segments, each of which is discussed in much more detail later in this book. 

It takes almost a year from the time a fiber supplier starts delivering fibers for yarn manufacturing until the completed garment is ready for sale in the retail store. The fiber shipments stop about four months before the start of the retail season. The yarn manufacturers begin delivering their yarns to the mills about nine months before the garments are to be sold in the retail stores and stop about two months before. The finished fabrics start to be shipped to the garment manufacture about six moths before and continue to be sold into the retail-selling season. 



Some apparel manufactures start cutting fabrics four months before the season and many continue to cut after the season has begun. There are two main retail-selling seasons for apparel. They are fall and spring. The former starts about August first and the latter begin about February first. The other seasons include summer and Holiday.
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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.

Flame Resistant Textiles by Flame Resistance Finishing

F1ame-Resistant Textiles 
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Textile products can be made flame resistant by using fibers that are inherently flame resistant or by application of a flame resistant finish. Modacrylic fibers offer adequate flame resistance at a moderate cost and have some use in carpets, curtains, and children’s sleepwear. Many other synthetic fibers shrink from ignition flames, providing some protection. Untreated polyester and nylon, for example, will pass the test for children’s sleepwear based on this characteristic. 

The more thermally stable materials such as asbestos, glass fiber, the aramids, PBI, and PBO could be called fireproof substances that will not burn. Glass fiber has many industrial uses and may be used to a limited extent in household textile products such as window shades or lamp shades. Thermally stable synthetic fibers have not been developed for general use but rather are intended for specialized protective clothing for industrial and military uses. Not only are they expensive, but they also lack the aesthetic features that would make them useful in consumer products. 

For fibers that are not flame resistant, a flame-retardant treatment can be applied. Durable finishes for cotton and cotton blend fabrics contain phosphorus which reacts chemically with the fibers and inhibits the production of compounds that fuel the flame. Commercial flame-retardant finishes are Pyrovatex, Proban, and Pyron, the latter produced by Ciba Chemicals. 

Finishes for synthetic fibers have bromine that quenches the flame by reducing the generation of flammable gases. Tris-2, 3- dibromopropyl phosphate (TRIS) was used for several years to impart flame resistance to nylon and polyester, but was suspected of causing cancer in laboratory animals. Since its removal from the market, and modifications in the test procedure for children’s sleepwear, nylon and polyester are not usually finished with a flame-retardant treatment. 

A particular problem in textile flammability is the burning of cotton/polyester blends. Since polyester is less flammable than cotton, one would expect blended fabrics to be less hazardous than all cotton fabrics. This is unfortunately not the case, because the char left as the cotton burns serves to hold the melting and dripping polyester in the flame. This is referred to as a “scaffolding” effect that prevents the polyester from dripping away, as it would do in a 100 percent polyester fabric. 

The polyester remains in the flame and contributes to the burning. Wool is inherently moderately resistant to burning and provides some protection in apparel and interior furnishings. For more stringent uses such as airplane seats, however, wool is given a flame-retardant treatment. A common finish for wool is Zirpro. performance standards that materials are required to meet are set forth in the CFR. These tests described above usually have a single pass/fail criterion. A wide variety of additional tests for flammability can be conducted to provide information on burning behavior and effectiveness of finishes. 

Many of these methods require test samples of considerable size or even whole garments. DuPont, Eastman Kodak, and the University of Minnesota have developed thermal testing manikins with heat sensors located in various parts of the figure. Tests performed using these figures can determine not only the combustibility of the fabric being tested but also the location of hot spots and can furnish data about the transfer of heat. They can also assess effects of fabric layers such as a cotton dress worn over a nylon slip. 

There are tests for carpets other than the pill test required by the federal standard. The Flooring Radiant Panel Test is said to simulate conditions of interior fires more effectively than other carpet tests. As a result, it is likely to be used by governmental and other regulatory agencies that require the more extensive product evaluation that carpeting installed in hospitals and facilities participating in Medicare and Medicaid programs must meet. 

An area of considerable interest in flammability testing of interiors is computer simulation or virtual tests to determine the hazards of real-life situations. For example, data on the furnishings in a prototype room can be used to predict the results of a fire (Gorman 1994). More realistic measures of fire hazards can be obtained and used in such predictive models. 

These measures, including total heat release, rate of heat release, and toxic gases evolved, are the real dangers from fires involving textiles. resin holds yarns together at the points where the yarns interlace. Resin antis lip finishes are durable. Other antislip finishes can be created by coating silica compounds on fabrics. However, these finishes are only temporary.
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