Repellent finishes fluorocarbon-based repellents

Permanent antistatic fmishes, based on crosshnked polyamines and polyglycols, need an alkaline catalyst. Therefore the one-bath combination with finishes, which need acid catalysis, is difficult but not impossible. Examples of acid-catalysed fmishes are the easy-care and durable press fmishes, durable hydrophylic silicone softeners and elastomeric finishes, also fluorocarbon-based repellency and some flame-retardant finishes. High finish effects result from a two-bath application with of the easy-care finish first followed by the surface-related antistatic finish. 

Several smdies have been conducted on the use of plasma for water-repellent deat-ment of fabrics (Ceria and Hauser, 2010 Leroux et al., 2008 Di Mundo et al., 2009). Most of these studies have used fluorocarbon-based chemistry however, none of them attempted a dual treatment with antimicrobials. One study combined a water-repellent finish with a flame-retardant finish (Tsafack and Levalois-Griitzmacher, 2007). Moreover, a review paper entitled Non-thermal Plasma Treatment of Textiles provides a comprehensive review of how nonthermal plasma was used effectively to impart different properties to textiles such as hydrophihc, hydrophobic, and oleopho-bic properties (Morent, et al., 2008). 

Lately substitution of hazardous substances has become a hard task for fabric finishing companies. Substances such as easy-care products, fluorocarbons for water- and oil-repellent properties, various flame retardants (halogen or phosphor-based), plasticizers... 

Fluorocarbons are known to introduce durable water and oil repellency (DWOR) and, as such, they are apphed in water- and stain-repellent fabrics for apparel. The combination of water and oil repellency is a typical behavior of fluorocarbon products. In the past, finishes based on C8 fluorocarbons (eight carbon atoms in the structure) were mainly used. However, concerns arose associated with these C8 fluorocarbons, more specifically with respect to PFOA (perfluorooctanoic acid or pentadecafluorooctanoic acid) and PFOS (perfluorooctane sulphonate or heptadecafluoro-l-octanesulfonic acid). 

The tendency is to replace the C8 fluorocarbon chemistry by C6 or C4 fluorocarbon products or even fluorine-free water repellents. Currently, new commercial DWOR finishes are coming onto the market based on short chain fluorocarbons (C6 or C4 fluorocarbon chemistry), hybrid systems, or they are fluorine free. 

Recent experiments by the authors studied the water repellence of PET fabrics (technical fabrics), photochemically treated in the presence of, e.g., 1,5-hexadiene, 1,7-octadiene, diallylphthalate (DAP) and l//,l//,2//,2H-perfluorodecyl acrylate (PFDA). Exemplary experimental data are summarized in Fig. 13 showing drop penetration times in excess of 1 hour (measurements were stopped after this time) and DuPont grading of up to 8. The relevant values for the untreated fabrics were drop penetration time approx. 20 s and a DuPont grading 0. Based on the well-known effect of heat treatments on long-chain fluoro compounds (cf. Sections 4 and 5.1), the samples treated with PFDA were also characterized following a further heat treatment. As was found in the case of wet-chemical finishes and plasma-deposited fluorocarbon thin layers, the water repellence of the samples could be further enhanced by heat treatment in this case also. 

In encapsulated continuously working plasma units (Fig. 15.7), oil repellency grades of 5-6 (according to AATCC 118-1992) have been obtained on PET-Monofil fabric at a process speed of 0.5 m/min (Fig. 15.8). Better oil-repellent properties than those of PTFE were obtained, but the properties of water-based FC finishing have not been completely achieved until now. Oil repellencies on treated fabrics increase with decreasing process speeds, increasing fluorocarbon layer thicknesses. The thickness of plasma polymerized... 

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