Surface finish fluorinated

A further interesting property that is induced by surface fluorination is a roughening716 ofthe surface, leading to a matt or frosted texture. Currently this is a highly desirable surface finish for certain cosmetic containers. 

Y. Qinhuan, Z. Tingyou, L. Zhengjun, Characterization and application of low surface energy fluorinated polymer in leather finishing, J. Soc. Leath. Tech. Chemists 94 (3) (2010) 106-110. 

Tables 6.31 and 6.33 show dimensions and properties of partially fluorinated fluoroplastic films. These films are available with different surface finishes such as one side polished, Haircell, or dull. Films with both sides polished or matte are also available.

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. 

The Aerosol Fluorination process [42] (Aerosol) is operated on the principle that the substrate is absorbed onto the surface of fine sodium fluoride particles in the fluorination apparatus in which the fluorine concentration and the temperature increases along the length of the reaction vessel. A U.V. photo-fluorination finishing stage completes the perfluorination process which has the advantage that it is a continuous flow method. 

Surface fluorination has been claimed to make polyethylene less permeable to gasoline and nonpolar solvents in general. Fluorine gas can be used to blow the container, which treats only the inside surface. Or the finished container can be fluorinated both inside and outside in a single post-treatment. This produces a fluorinated layer 20-40 nm thick. 

Imidodisulfuryl fluoride,f 18.5 g. (0.102 mole), is loaded into a Pyrex U-tube containing a small magnetic stirring bar. The U-tube is attached to the fractionation train on the vacuum line, and the train is flushed with helium. The two adjacent U-tubes are cooled to —78°, and the last U-tube is cooled to —196°. The two —78° traps should be packed with Pyrex helices to ensure efficient trapping. The fluorine tank is opened, and the concentration of fluorine is adjusted to approximately 30%. The helium-diluted fluorine is passed over the surface of the imidodisulfuryl fluoride at ambient temperature and at a flow rate of 150-175 ml./minute for appro.ximately 2 hours or until most of the imidodisulfuryl fluoride has disappeared from the U-tube. After the fluorination is finished, the system is flushed for 15 minutes with helium and then evacuated. The contents of the two —78° traps [crude FN(SOiF)2] are combined. Final purification is achieved by slow fractionation through U-tubes maintained at —33° (bromobenzene slush) and —78°. The former trap retains approximately 1 g. of imidodisulfuryl fluoride the —78° trap collects 15.3 g. (75% yield) of fluoroimido-disulfuryl fluoride. Anal. Calcd. for FN(SO F)2 N, 7.03 S, 32.3 F, 28.6. Found N, 7.11 S, 32.7 F, 28.8. 

Defoamers are used in fibre finishes in order to inhibit the formation of foam during the manufacturing and application of the finishes. Silicones and fluorochemicals are outstanding defoamers. They have very low surface tension and limited solubility in many organic compounds. They can quickly reduce the local surface tension of bubbles to create an imbalance of surface tension which leads to the easy rupture of bubbles. Silicones can be analysed using FUR. The analysis of fluorochemicals is difficult because fluorochemicals, especially perfluoro compounds, are resistant to many reagents. One microdetermination of fluorine by alkali fusion in a metal bomb was reported. Since it is too complicated and specialised apparatuses are used, this method is not introduced here. 

Two contrasting IR spectroscopic techniques, ATR and photoacoustic spectroscopy, were investigated as means for the determination of fluorocarbon polymer finishes on wool fabric. Based on the experimental conditions used, the results of the photoacoustic spectroscopy method are more characteristic of the bulk sample, while the ATR results are more surface specific. Linear calibrations between polymer addition, as determined by total fluorine analysis, and the absorbance of the C-F stretching bands of the normalised spectral data were obtained for a typical commercial fluorocarbon polymer. The quantitative methods developed are used to help access the effects of wear and the subsequent heating of fluorocarbon polymer-treated fabric samples. 21 refs. 

N-substituted, long-chain alkyl monomethylol cyclic ureas have also been used to waterproof cotton through etherification. Other water-repellent finishes for cotton are produced by cross-linked silicone films (117). In addition to the poljunerization of the phosphorus-containing poljuners on cotton to impart flame retardancy and of silicone to impart water repellency, polyfluorinated polymers have been successfully applied to cotton to impart oil repellency. Chemical attachment to the cotton is not necessary for durability oil repellency occurs because of the low surface energy of the fluorinated surface (118). 

At the same time both the thermal stability and the chemical resistance to acids and alkalis are improved. Huorinated PE sheets exhibit a lowered coefficient of friction and acceptance of printing inks is improved. The finishing of plastic surfaces by direct fluorination is not limited to polyethylene. Principally, any kind of plastic or rubber surface could be fluorinated. 

The characteristics of fluoropolymers are summarized in Table 1. Thermal and chemical resistance is in general with most of plastics, elastomers and perfluorinated membranes. Weather resistance with the outdoor durability for more than 20 years is specific for fluorinated paint resins. Surface properties such as water and oil repellency are provided by acrylic polymer-based textile finishes and coatings with long-chain per-fluoroalkyl groups. Electrical properties as well as a low refractive index are important for optoelectronics applications like optical fibers. 

The repellency of fluorocarbon finishes depends on the structures of the fluorocarbon segment, the nonfluorinated segment of the molecule, the orientation of the fluorocarbon tail, the distribution and the amount of the fluorocarbon moiety on fibers, and the composition and geometry of the fabric [101]. The relationship between repellency and the structure of the fluorocarbon segment is in accord with the critical surface tension concept developed by Zisman and co-workers (see Chapter 11). Shafrin and Zisman [102] determined the wettabilities and critical surface tensions of -perfluoroalkyl substituted 77-heptadecanoic acids synthesized by Brace [103]. Once the seven outmost carbon atoms are fully fluorinated x = 7), the wettability of monolayers of the acids F(CF2)a(CH2)i6COOH approaches that of the perfluorocarboxylic acid F(CF2).vCOOH (Fig. 12.2). This suggests that a terminal perfluoroalkyl chain of seven carbon atoms is sufficiently... 

The molecular refraction is an additive function of atomic refractions. Fluorine has the lowest atomic refraction (Table 13.1) of the atoms used to build compounds or polymers for coating fiber surfaces. Consequently, the refractive index and polarizability of fluorocarbons are lower than those of the corresponding hydrocarbons and chlorocarbons. Because dispersion forces constitute the major part of their cohesive forces, their surface energy is low. However, a low-surface energy is not the sole criterion for an effective soil retardant. The dispersion forces are effective only over short distances. A finish deformable by soil particles provides a larger area in close contact with soil than a finish that does not flow on impact. Hence, hardness of finish is also important. Soiling can also be affected by a liquid film on fibers, such as oil or fat, which can fill the voids between the surfaces of soil and fiber and act as an adhesive. 

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