Dyeing operations

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. 

Although designed to color the fiber, dyeing operations also impart large amounts of permanent set to wool. 

The formulation of a carrier depends on four considerations (/) the carrier-active chemical compound (2) the emulsifier (J) special additives and (4) environmental concerns. Additional parameters to be considered in the formulation of a carrier product with satisfactory and repeatable performance arise from the equipment in which the dyeing operation is to be carried out. The choice of equipment is usually dictated by the form in which the fiber substrate is to be processed, eg, loose fiber, staple, continuous or texturized filament, woven or knot fabric, yam on packages or in skeins (see Textiles). 

Develop a detailed process scheme for decolorizing recycle water used in a fabric dyeing operation. Assume the operation to be continuous. Develop a detailed list of all parameters that impact on the operation of a carbon filter. 

The US Environmental Protection Agency recently announced its intention to develop and implement new Clean Air Act Standards for industrial coatings operations within the next year. These emission standards will eventually require companies involved in fabric printing, coating and dyeing operations to comply with Maximum Achievable Control standards. The Hazardous Air Pollutants emission limits that will apply to facilities and the impact on fabric coating operations are discussed. USA... 

Supercritical fluids also find application in the areas of pollution prevention and remediation, and supercritical carbon dioxide is used as a replacement solvent for many hazardous solvents in both extraction and separation processes and also as a reaction medium and in materials processing. Although carbon dioxide is considered as a greenhouse gas , there is actually no net increase in the amount of the gas if it is removed from the environment, used as the solvent instead of a hazardous substance, and returned to the environment. In this way, most of the uses of supercritical carbon dioxide may be considered as environmentally friendly. Because the solubilities of oils and greases in carbon dioxide are high, it is particularly suited to the cleaning of machinery 47 and, as discussed in the literature 48, it is used as a solvent in textile dyeing operations where it is used to treat any dye-laden... 

Figure 10 Sources for colored wastes from textile dyeing operations (from Ref. 55).

Sulfamic acid is also used in some dyeing operations for pH adjustment however, it is useful in lowering pH levels in a variety of other systems. The low pH persists at elevated temperatures and there are no objectionable fumes. 

Dyes are significant because of these production volumes and their potential release into the environment from manufacture, processing, and use. Spent dye solutions from textile dyeing operations ultimately are discharged to surface water after some form of waste-water treatment, and dyes not effectively removed from the wastewater may result in environmental and human exposure. 

Dye-containing solid wastes, including cleanup wastes from manufacturing and textile dyeing operations, are likely to enter landfills, where aerobic and anaerobic biodegradation, sorption to soils, and leaching may occur. 

Dynamically formed membranes were pursued for many years for reverse osmosis because of their high water fluxes and relatively good salt rejection, especially with brackish water feeds. However, the membranes proved to be unstable and difficult to reproduce reliably and consistently. For these reasons, and because high-performance interfacial composite membranes were developed in the meantime, dynamically formed reverse osmosis membranes fell out of favor. A small application niche in high-temperature nanofiltration and ultrafiltration remains, and Rhone Poulenc continues their production. The principal application is poly(vinyl alcohol) recovery from hot wash water produced in textile dyeing operations. 

Besides quantifying thermal and mechanical behaviors of dry materials, recent developments have enabled samples to be immersed in liquid and vapor media (e.g., Bao and Bagga, 1993 Price, 1997). This advancement enables characterization of actual material performance under environmental conditions (e.g., dyeing operations) when materials are in contact with various solvents. 

Other substantial benefits derive from reducing the wet pick-up in wet finishing and continuous dyeing operations. 

Pure acrylonitrile may polymerize at room temperature to polyacrylonitrile (PAN), a compound that, unlike polyamides and polyesters, does not melt at elevated temperatures but only softens and finally discolors and decomposes. Nor is it soluble in inexpensive low-boiling organic solvents. Because fibers made from it resist the dyeing operations commonly used in the textile industry, the usual practice is to modify it by copolymerization with other monomers, for example, vinyl acetate, styrene, acrylic esters, acrylamide, or vinyl pyridine in amounts up to 15 percent of the total weight (beyond which the final product may not be termed an acrylic fiber). The choice of modifier depends on the characteristics that a given manufacturer considers important in a fiber, the availability and cost of the raw materials in the manufacturer s particular area of production, and the patent situation. 

FACEGARD A can be incorporated in the pad steam dyeing operation of acrylic tow, top and piece goods or copolymers that contain acrylics. 

FACEGARD A, when used in the dyeing operation, will result in additional shrinkage and additional bulk to the acrylic fibre. 

Is a newly developed non-silicone defoaming agent designed for use in jet dyeing operations to give effective anti-foaming properties, and show immediate knock-down of foam. 

This material is an anionic fixing agent designed for the fixation of acid colors in Nylon dyeing operations. 

These are resin bonded, nonionic aqueous colors designed for pad dyeing operations. Added resin binders are required. 

Acceptor for exhaust pigment dyeing of cotton in garment dyeing operations. 

Powerful sequestering agents for iron over a broad pH range. Effectively control iron and other trace metals in scouring, bleaching, and dyeing operations. Also sequesters calcium and magnesium hardness. 

INTEX DEFOAMER 138 is a formulated low silicone antifoam and defoamer. It is formulated with a selected blend of low foam emuslifiers to assure compatibility with all dyestuffs and auxiliaries normally used in dyeing operations. 

TEX-WET 1158 is also used in the dyeing operation for synthetic fabric, since it will help dye penetration by improving the wet-out of the fabric. 

Wastewater treatment. The effluents from textile processing contain some pollutants and become highly colored due to soluble and insoluble dyes. At present, there is no economically feasible method for removing the dyes and other chemicals present in the effluents from the finishing and dyeing operations. 

Uranium compounds have had other limited uses. For example, they have been used as mordants in dyeing operations. A mordant is a material that helps a dye stick to cloth. Uranium oxide has also found... 

Xanthorhamnin is not a dyestuff, and it must therefore be accepted that rhamnetin is formed in the dyeing operations. 

Activated carbon has been tested for the cleanup of highly colored waste streams such as result from dyeing operations [78]. Coal carbons are 99% effective for dye removal and accept dye loadings as high as 0.40 kg dye/kg carbon. Lignite carbon is also useful, but less effective. 

The waxes are important in the spinning process but a hindrance to the dyeing operation. Owing to their water-repellent natuie, waxes prevent the proper absorption of the dyestuff. The natural color of cotton and the other impurities also interfere, but to a lesser degree, with the ordinary processes of dyeing, printing and finishing. ... 

Silica suspended in water can interfere with certain dyeing operations and can cause visible turbidity, as discussed in the introduction to this chapter. Various forms of silica can be determined by any one of several methods as described in Standard Method 4500-Si. For textile use, total silica is the most important. This may be determined gravimetrically by Standard Method 4500-Si-C or by atomic absorption spectrometry by Standard Method 311 ID (Standard Methods, 1998). For information of atomic absorption methods, see the Metals section below. Also, since the detrimental effects in textiles are related primarily to fdtering of the silica on beam and package machines, it often suffices to measure the total suspended solids (TSS) in the water supply. TSS testing is described later in this chapter and is simpler than silica testing. 

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