Repellents fluorinated

Hydrocarbon repellents and their mixtures with fluorinated repellents, silicone and fluorosilicone repellents, and fluorinated repellents are described in Chapter 12. Fluorinated soil retardants are discussed in Chapter 13 and soil- and stain-resistant carpets in Chapter 14. 

The theory of repellency is discussed in Chapter 11. The relationship between repellency and the structure of the fluorinated repellent is in agreement with the critical surface tension concept developed by Zisman [319]. Shafrin and Zis-man [320] determined the critical surface tensions of fu-perfluroalkyl-substituted -heptadecanoic acids and the wettabilities of their monolayers. The wettabilities... 

Fig. 11.8 Area covered by the spreading liquid versus oil repellency (areas covered in 60 s by 0.10 mL n-heptane spreading on a 65 35 poly(ethylene tereph-thalate)-cotton blend fabric finished with various fluorinated repellents). (From Ref. 59.)...

Repellents have hydrocarbon, polysiloxane. and/or fluorocarbon hydrophobes. Only fluorinated repellents are oleophobic and repel both water and oil. 

Hydrocarbon-based repellents are relatively inexpensive but they repel only water. They do not impart oil and soil repellency to textiles. In contrast, fluorinated repellents provide oil and soil repellency as well as water repellency. However, the higher cost of fluorinated repellents limits their applications. To lower the cost of repellent finishing, fluoropolymers are usually coapplied with hydrocarbon-type repellents. With a hydrocarbon repellent as an extender, fluorinated repellents can be used at a lower concentration without an adverse effect on repellency [43-57]. 

The effect of nonfluorinated repellents on the performance of fluorinated repellents is complicated by other adjuvants in the finish, such as cross-linking agents for cotton, softeners, and sewing aids. The interactions between the various components and their effect on repellency and physical properties of the fabric must be considered when formulating a repellent finish. 

An extender effect can be achieved as well by including a long-chain alkyl group in the fluorinated repellent polymer (e.g., by copolymerizing a fluorinated acrylate or methacrylate with stearyl acrylate) [60-62]. 

Table 12.3 Specifications for Fabric Protected with a Fluorinated Repellent...

Coffee stain has remained a formidable challenge, A protective fluorinated finish retards the diffusion of the stain into fibers. However, when coffee penetrates the fluorinated repellent finish, stain-resist agents in the fibers must hinder staining by coffee. 

The first defense line against staining is the fluoiinated soil retardant (see Chapter 13) which reduces soiling with particulate soil and hinders wetting of fibers. When a liquid is spilled on the carpet, the fluorinated repellent provides time for the removal of the liquid by blotting before the liquid wicks into the carpet. However, if the liquid is allowed to wick into the carpet, a stain-resist agent in the fiber surface or inside the fibers must prevent staining. 

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