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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Textile Finishing; Stain Repellency and Stain Resistant Finishing

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There are some textile products or fabric those used long time without any types of wash. So some special care must be taken for those materials. Stain Repellency finishing and Stain-Resistant Finishing are those special treatment whish ensure the proper care of the textile material. This types of finishing also cares from oil and wax. 

Stain Repellency finishing: 

Scotchgard and other finishes that repel water and oil may be classified as stain resistant finishes. These finishes decrease the surface energy of the fabric so that water or oil beads up rather than penetrating the fiber. Illustrates this principle with two different stain-repellent finishes: fluorochemical and silicone. The fluorochemical finish, like DuPont’s Teflon finish on cookware, prevents both oil and water from penetrating the fabric surface. The silicone finish, which also coats the fabric, repels water but not oil.Soil-Release Finishes 

Soil-release finishes were developed largely as a result of the tendency of durable press and polyester fabrics to absorb and hold oilborne stains. The soil-releasing finish should not be confused with stain-repellent finishes, although Scotchgard is both stain resistant and soil releasing. Soil-release finishes alter the characteristics that cause soil to bond to the fibers. Agents such as polyethylene glycol derivatives may be added to the polymer solution before extrusion to make the nonabsorbent fibers more hydrophilic (“water loving” or having a strong affinity to water). Other finishes may form hydrophilic grafts on the fiber resulting in improvements in soil release and soil redeposition. Most soil-releasing finishes are applied during the finishing of the fabric and are compatible with durable pres; finishes. 

Some fluorochemical finishes are dual-acting. They are block copolymers of fluorocarbons and polar segments such as esters. In air the fluorocarbon sections come to the surface to repel oily substances. When the finished fabric is immersed in water, however, the polar hydrophilic sections predominate on the surface, attracting water to help release soils. At the same rime that soil-releasing finishes increase the receptivity of fibers to water, a second benefit is gained. Static electricity buildup is decreased as absorbency is increased. 

Increased absorbency also increases the comfort of the garment in warm weather. Fuzzing and pilling seem to be decreased by soil releasing finishes as well, because the finish also lubricates the fabric. Effective soil-releasing finishes should result in fabrics from which common soil is removed during home laundering with normal detergents. Oily stains, often hard to remove from durable press fabrics, should be removable in home laundering. The disadvantage of most of these finishes is that they are gradually diminished through laundering. 

Stain Resistant Finishing: 

Stain-resistant finishes for nylon carpets were developed to increase the resistance of these carpets to food and other common stains. The finishes are generally sulfonated aromatic condensation (SAC) compounds that function essentially as colorless dyes. The stain blockers, which have negative charges, are attracted to the positive sites in the nylon fibers, tie up the dye sires, and set up a barrier layer to staining materials. Many food stains, for example, which are negatively charged like the stain resist molecules, are not absorbed as easily. Today, stain-resistant finishes are used on most nylon carpets for residential use. One trademark is DuPont’s Stainmaster.

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Textile Finishing; Waterproofing finishing, Soil and Water Repellency finishing

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Textile Finishing and Fabric finishing is very important terms in textile manufacturing area. We need some special task with textile material to meet the buyer requirement. We know that natural fibres as well as textile fabric manufactured with natural fibre absorb the water. So it easily passes water with their surface. If we want to protect passing water or making the water proof fabric surface, we need to do some special treatment to surface of the fabric. This could be known as water proofing finishing. This is similar for Soil and Water Repellency finishing. The term water repellent should not be confused with the term waterproof Water-repellent fabrics resist penetration by water but are not completely waterproof. Such fabrics represent a practical alternative to fabrics that keep out water and air.

Waterproofing finishing: 

For a fabric to be truly waterproof, it must be completely sealed with a substance that is insoluble in water. The familiar rubber coated garb of police officers and firefighters is a good example. Modern waterproofing materials include the vinyl resins, which do not oxidize and crack as readily as rubber. Synthetic rubbers are also more durable to outside influences than natural rubber. The fabrics used in most of today’s waterproof materials are cotton and nylon. The latter, coated with vinyl resins, has largely superseded the heavy canvas tarpaulins used to protect merchandise in transit. A fabric that is waterproof allows no water to penetrate from the surface to the underside. Coatings made from rubber or synthetic plastic materials can create fabrics that are completely waterproof; however, these fabrics tend to be warm and uncomfortable because they create a barrier that traps air and perspiration close to the body.

The dilemma of providing protection and comfort was resolved by the development of fabrics that are described as waterproof and breathable (WP/B). The general principle behind these fabrics is that they keep out water from rain and snow but allow the passage of moisture vapor from perspiration. They are promoted for use in outdoor clothing and for active sports. One of the first of these products was Gore- Tex, made by placing a membrane of fluoropolymer underneath a layer of outer fabric. The membrane is porous.

The pores are smaller than a drop of water that contains many water molecules, but they are larger than a molecule of water vapor. This structure keeps out rain but allows moisture from perspiration to escape.

The success of Gore- Tex has led to the production of other products using similar principles. Many of these use polyurethane coatings with microscopic pores. Sympatex, a polyester membrane for lamination, is nonporous but breathable. A charged outer surface attracts polar water molecules which are drawn through the membrane. Also helping to “push” moisture vapor through is the high vapor pressure on the body side (Sympatex 1988).

Soil and Water Repellency finishing:

Soiling results when a textile comes into contact with soiled surfaces or with air- or waterborne soils. Soil is retained either by mechanical entrapment of soil particles within the yarn or fabric structure or by electrostatic forces that bond the soil to the fabric. One way to approach the problem of soiling is to prevent its deposition on the fabric. Another is to seek ways to facilitate its removal. Special finishes have been developed that have taken both of these approaches.

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