Fluorochemical fibers

Fluorochemicals repel both water and oU because they produce an extremely low energy surface (18—26). The effectiveness of the fluorochemicals depends upon uniform surface coverage and orientation of the molecules on the fiber surface so that the perfluoroalkyl chains are directed away from the surface. The result is a GST as low as 5—10 mN /m (dyne/cm). Fluorochemical finishes are often formulated with nonfluorinated resin-based water-repeUent extenders. These water repeUents not only reduce the cost of the finish but may also improve durabUity (27,28). 

Many fluorochemical finishes for fabrics require curing at up to about 175°C. Curing aUows melt-spreading of the fluorochemical to ensure maximum leveling of the finish on the fibers and to promote optimum orientation of the pendant fluorinated portion of the molecules on the fibers. 

Silicones. SUicones are exceeded only by fluorochemicals in the volume used as repeUents for textiles. They are widely used on ceUulosic and synthetic fiber fabrics. SUicones provide water-based stain resistance good durabUity to washing improved tear strength a soft, sUck hand and improved fabric sewabUity. 

The water repeUency of sUicone finishes results from the low CST (ca 22 mN/m or dyne/cm) produced by the methyl groups in the sUicone that are oriented away from the fiber surface. The CST is lower than that produced by any class of compounds except for fluorochemicals. 

Carpet. Carpet, an important textile, may also be treated to provide water and oU repeUency however, the principal functions of the current carpet treatments are to provide soU and stain resistance. High quaUty carpets, especiaUy those made from nylon, polyester, or wool, have a significant proportion of the surface coated with fluorochemical materials. The treatments can be spray-appUed to a finished carpet or appUed directly to the fiber during the spinning or dyeing operations. Suitable fluorinated resin materials are readily avaUable from 3M or DuPont. 

ARIDRY FC Extra is a new aqueous fluorochemical finish designed to impart lasting high oil and water repellence together with dry soil resistance to all fibers including cotton, rayon, wool, nylon, acrylics, polyester and is especially recommended for upholstery fabrics, drapery, slipcovers and other woven materials where dry-soil resistance is of importance. 

CNC ARIDRY C is a water repellent designed primarily as semi-durable to durable water repellent for most hydrophobic fibers, especially nylon. This product is also an excellent extender for fluorochemical finishes. 

NORANE F repellent is designed to work with nonionic and cationic fluorochemical emulsions to improve water repellency without detracting from the oil repellent nature of the fluoro-cheraical. The use of NORANE P repellent reduces the amount of fluorochemical necessary to meet specifications. NORANE F repellent also provides a soft hand to most fibers and blends. 

Fluorochemicals. Fluorochemicals are the most important class of repellents for textiles. They are the only repellents that provide repellency to water, waterborne stains, oil, oilbome stains, and oily particulates. The various products have a variety of repellency and durabiHty properties for certain fabrics, and the specific compositions ate proprietary. The first company to market fluorochemical repellents was 3M iu the 1950s (Scotchgard Fabric Protector), followed by DuPont (Zepel and Teflon Fabric Protectors). Several other companies such as Autalux Corporation, Ciba Specialties, Eastern Color Chemical, Glo-Tex Chemicals, IVAX Industries, Liadley Laboratories, NICCA U.S.A, Piedmont Chemical, Sedgefield Specialties, Sequa Chemicals, and Yorkshire Pat-Chem also market such finishes (17). Fluorochemical finish appHcation areas include rainwear, upholstery, drapery, and automotive fabrics, roofing materials, and carpeting. Both natural and synthetic textile fibers can be treated. 

Repellent finishes are important components of many protective textiles. Apphca-tions for repellent textiles range from medical textiles to raincoats. The low surface energies provided by repellent finishes can keep solid and liquid soils from adhering to treated fiber surfaces. Finishes based on hydrocarbon and silicone chemistries can yield water repellent textiles, while fluorochemicals are necessary to achieve the low surface energies needed for dry soil and oil repellency. "... 

BarpeL [Apollo] Fluorochemical oil and water rq>ellent for use on synthetic and natural fibers. 

Many analyses easily cross industry fines. The chemical and pharmaceutical industries are interested in the analyses that determine the coating weight of a coated particle such as with a time-released dmg. Like the spin finish on fibers, the coating has a different relaxation rate than the encapsulated material. Fluorine analysis is another unique application of NMR technology since the signal derives from the fluorine nuclei rather than hydrogens. The materials for which this technique for process analysis and control might be used include toothpaste, fluoropolymers and fluorochemicals. 

In 2000, 3M stopped the production of PFOA-, and PFOS-related products (C8 fluorocarbons). They developed new C4-based fluorocarbons free of PFOA and PFOS. Scotchgard protector Stain Release PM 490 and PM 492 are fluorochemical urethanes, which exhibit lower repellency but better stain release compared to fluorocarbons. Scotchgard Protector Dual Action repel and release PM900 and PM 930 are C4 fluorocarbon resin solutions, designed to improve the water repellency of textile fabrics and especially the oil repellency. These products also have a release effect. The products are designed for a variety of natural and synthetic fibers, including cotton and microfiber. 

The coverage of fiber surfaces by the fluorochemical repellent is a very important variable affecting repellency. Hence, the amount of a fluorochemical needed for maximum repellency depends on the fabric construction (Fig. 12.4) and the structure of the fluorochemical repellent. 

The monomeric fluorochemical repellents were superseded by fluoropoly-mers. However, the interest in monomeric fluorochemical repellents is increasing again. Modification of the fiber surface by (1) copolymerization with a fluorinated monomer (e.g., acrylonitrile copolymerized with l//,l/if,2/i/,2i7-heptadecafluo-rodecyl methacrylate [133], (2) adding fluorochemicals to the polymer melt [134-140], or (3) by applying fluorochemicals to preformed fibers [141,142] is being explored and exploited commercially. 

Wool fibers contain amine groups like nylon and the staining characteristics and stain-resistant treatments are similar to these of nylon [7,8]. Polypropylene and polyester fibers are less vulnerable to staining by synthetic food dyes than nylon but need fluorochemical protection against traffic soiling. 

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