Flame-retardant finishes fabrics treated

A resinous flameproof product which provides flame retardancy to polyester fabrics and blends. The flame retardant properties are durable to many launderings. A mild after-wash following drying of treated fabrics will provide a soft flame retardant finish. 

Fabrics should be tested after a defined wash or durability test which, in the case of Part 7, for fabrics treated with a flame retardant, is a single specified wash cycle. Only so-called durable flame retardant finishes as described in Chapter 8 will pass such a wash cycle since semi-durable treatments are usually only resistant to dry cleaning or simple water soak tests specified in BS 5651 1989, for example. Fabrics containing inherently flame retardant fibres such as Hi-modified polyester (e.g. Trevira CS ), polyacrylics (e.g. modacryUcs such as Kanekaron ), and polypropylene do not require a prewash treatment prior to testing. 

Considerable effort is being made (ca 1993) to develop satisfactory flame retardants for blended fabrics. It has been feasible for a number of years to produce flame-resistant blended fabrics provided that they contain about 65% or more ceUulosic fibers. It appears probable that blends of even greater synthetic fiber content can be effectively made flame resistant. An alternative approach may be to first produce flame-resistant thermoplastic fibers by altering the chemical stmcture of the polymers. These flame-resistant fibers could then be blended with cotton or rayon and the blend treated with an appropriate flame retardant for the ceUulose, thereby producing a flame-resistant fabric. Several noteworthy finishes have been reported since the early 1970s. 

THPOH—Ammonia—Tris Finish. By far the most effective finish for polyester—cotton textiles was a system based on the THPOH—NH treatment of the cotton component either foUowed or preceded by the appUcation of Tris finish to the polyester component. This combined treatment appeared to be effective on almost any polyester—cotton blend. A large amount of fabric treated in this way was sold throughout the United States and much of the rest of the world. Shortly after the introduction of Tris finishing, Tris was found to be a carcinogen. Most of the Tris treated production was in children s sleepwear, and this created a situation in which almost aU chemical fire-retardant-treated textiles were unfairly condemned as dangerous. Manufacturers mshed to replace chemically treated textiles with products produced from inherently flame-resistant fibers. Nowhere was the impact more severe than in the children s sleepwear market. New, safer materials have been introduced to replace Tris. Thus far none has been as completely effective. 

THPC—Amide—PoIy(vinyI bromide) Finish. A flame retardant based on THPC—amide plus poly(vinyl bromide) [25951-54-6] (143) has been reported suitable for use on 35/65, and perhaps on 50/50, polyester—cotton blends. It is appUed by the pad-dry-cure process, with curing at 150°C for about 3 min. A typical formulation contains 20% THPC, 3% disodium hydrogen phosphate, 6% urea, 3% trimethylolglycouril [496-46-8] and 12% poly(vinyl bromide) soUds. Approximately 20% add-on is required to impart flame retardancy to a 168 g/m 35/65 polyester—cotton fabric. Treated fabrics passed the FF 3-71 test. However, as far as can be determined, poly(vinyl bromide) is no longer commercially available. 

Phosphonium Salt—Urea Precondensate. A combination approach for producing flame-retardant cotton-synthetic blends has been developed based on the use of a phosphonium salt—urea precondensate (145). The precondensate is appUed to the blend fabric from aqueous solution. The fabric is dried, cured with ammonia gas, and then oxidized. This forms a flame-resistant polymer on and in the cotton fibers of the component. The synthetic component is then treated with either a cycUc phosphonate ester such as Antiblaze 19/ 19T, or hexabromocyclododecane. The result is a blended textile with good flame resistance. Another patent has appeared in which various modifications of the original process have been claimed (146). Although a few finishers have begun to use this process on blended textiles, it is too early to judge its impact on the industry. 

Both fiber producers and fabric mills have realized that many of the performance variants that are difficult to iacorporate iato fiber melt spinning can be accompHshed by post-treating yams or fabrics. Mills ia the 1990s can apply flame retardants, softeners, dye-fade inhibitors, and stain- and soil-resisting agents as part of the finishing of a fabric. 

Another version of finish apphcation with transfer rolls is the loop transfer system, Fig. 2.5.A loop of fabric is immersed in finish liquid and then squeezed with the fabric to be treated between squeeze rollers. The finish is transferred to the fabric at a much lower wet pickup than possible by direct immersion. These roll transfer techniques are especially useful for the backside application of finishes, for example hand builders and flame retardants, to pile fabrics (without crushing the pile). 

The first known fire-retardant process found durable to laundering was developed in 1912 (4). A modification of an earlier process (5), this finish was based on the formation of a tin(IV) oxide [18282-10-5] deposit. Although the fabric resulting from treatment was flame resistant, afterglow was reputed to be a serious problem, resulting in the complete combustion of the treated material through smoldering. 

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