Solvent extraction scouring

About 90% of the wool wax can be removed by this system. The recommended solvents are benzene, carbontetrachloride, solvent naptha, white spirit, trichloroethane etc. In one method solvent is applied under high pressure jet on the material placed on a permeable conveyer and dislodges much of the dirt and suint apart from removal of wax from the fibre [36]. The solvent content on the treated wool is reduced to about 45% by passing through the rollers and is further reduced to about 10% by centrifuging. Finally, the residual solvent is removed from the fibre by blowing hot air [37]. 

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Solvent Resistance. Elastomeric fibers tend to swell in certain organic solvents mbber fibers swell in hydrocarbon solvents such as hexane. Spandex fibers become highly swollen in chlorinated solvents such as tetrachloroethylene [127-18-4] (Perclene). Although the physical properties of spandex fibers return to normal after the solvent evaporates, considerable amounts of its stabilizers may have been extracted. Therefore, the development of stabilizers that are more resistant to solvent extraction has become important as solvent scouring during mill processing replaces aqueous scouring at many mills, especially in Europe (26). 

Other techniques aimed at improving grease recovery (and often attempting also to improve the scouring process itself) have included solvent degreasing of the wool (52,53), solvent extraction of the Hquor or sludge (178), aeration (179,180), and physical and chemical destabilization (175). 

Polyester/wool blends are very popular, the most common blend ratios are 55 45 and 70 30 polyester wool. Polyester rich blends are normally constructed from a texturised polyester fibre warp and 55 45 polyester wool weft yams. The 20 80 polyester/wool is woven from 55 45 warp and a pure weft yam. Worsted polyester/wool blend yams may contain 2.5 - 3% solvent extractable oil, compared with 3.5- 5% for similar all wool yams. The oils have much greater affinity for polyester fibre than wool and after normal piece scouring, the blends contain residual oil content of 0.6 - 1.2% compared with 0.3% for wool. Oxidation of combing oil is influenced by exposure to light which should be avoided before scouring. Addition of surfactant to combing oil improves the scourability of the blend fabric [75]. 

Scouring cotton by extraction with an organic solvent such as trichloroethylene, followed by flash evaporation, is making progress in practical application. Investigation by I.C.I. demonstrated that immersion in trichloroethylene for periods as short as 30 seconds would reduce fat and wax content to about OTS per cent, a figure which is within the tolerance of commercial acceptability. If the cotton is singed it is quenched with steam instead of water so that it enters the solvent extraction unit dry. 

MAJOR USES Used in the manufacture of phosphate, coumarin, salicylaldehyde, disinfectants, solvents, resins, scouring agents, herbicides extraction of ore. 

The effect of scouring with enzymes was compared to conventional caustic soda treatment and solvent extraction. Whereas caustic soda treatment resulted in the highest deterioration on a molecular level, but led to a high level of whiteness, the solvent-extracted samples showed superior tensile strength and the bioscoured samples the best softening effect. ... 

Most of the trichloroethylene produced is used for metal degreasing. Other important uses are in the scouring of wool and as an extractive solvent, e.g. for olive and soya bean oils. Minor uses are as a heat transfer medium, anaesthetic, insecticide and fumigant, paint remover and fire extinguisher. 

Trichloroethylene is an excellent extraction solvent for greases, oils, fats, waxes, and tars and is used by the textile processing industry to scour cotton, wool, and other fabrics (lARC 1979 Kuney 1986 Verschueren 1983). The textile industry also uses trichloroethylene as a solvent in waterless dying and finishing operations (McNeill 1979). As a general solvent or as a component of solvent blends, trichloroethylene is used with adhesives, lubricants, paints, varnishes, paint strippers, pesticides, and cold metal cleaners (Hawley 1981 lARC 1979 McNeill 1979). 

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