Exhaustion Process

Normal PAC textile material is dyed as cable or stock in packages, as yam in hanks or packages (direction of liquor inside to outside), as pieces on beam, overflow, paddle machines (knitwear), or drums (socks). High-bulk (HB) yams are dyed as muffs [161], Strongly soiled textile material is prewashed, preferably in a weakly alkaline bath. 

Because of the strong temperature dependence of exhaustion and the poor migration properties, dye absorption must be as level as possible from the start. Correspondingly, attention should be paid to uniform packaging, package density, liquor flow or movement of textile material, and controlled machine conditions. 

Additive Light hues Medium hues Deep hues 

Temperature range Stock, top Yam (pack.) Hank, piece 

Tend-Tmax (until absorption of dye is complete) quick quick quick 

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This group includes dyes that have their optimal fixation temperature between 80 and 95 °C. Such dyes show comparatively high exhaustion before fixation so it is important to ensure that dyeings are level. Salt should be added portionwise at specified stages during the exhaustion process, hence they are termed salt-controllable reactive dyes . 

Reactive Black 5 (7.127) by an exhaust process and optimal conditions for fixation were determined [140]. The substantivity of this agent for cellulose is not ideal, as it requires a high salt concentration to ensure a fixation level of 80%. To achieve 85% fixation of dye 7.127 by this method, an addition of 50 g/1 sodium sulphate was necessary [29]. 

The compression ratio of an air-standard Diesel cycle is 15. At the beginning of the compression stroke, the pressure is 14.7 psia and the temperature is 80°F. The maximum temperature of the cycle is 4040°F. Find the temperature at the end of the compression stroke, the temperature at the beginning of the exhaust process, the heat addition... 

A method to lower the release of chemicals, auxiliaries, and residual dyestuff in exhaust processes is dyeing on a standing dyebath. In such a technique the exhausted dyebath, which contains the auxiliaries, chemicals (salt), and dyestuff, is reused for the next dyeing after a replenishment of the exhausted dyestuff and lost chemicals. In fact, such techniques are not as widely in use as might be expected because a set of requirements has to be fulfilled to introduce them ... 

The most important emissions are residual waters deriving from the rinsing of pieces, exhausted process baths and from the draining originating during maintenance of the baths. An additional problem is represented by muds that are obtained in the processes of treatment of residual water, which must be confined given their toxic nature. 

The reactivity of monochlorotriazinyl dyes can be increased by replacing chlorine with fluorine (3), which allows the exhaust process to be carried out at 40°C [15],... 

Dioxazine Dyes. The synthetic routes (see below) to almost all dioxazines yield products with a symmetrical structure, resulting in at least two reactive anchors. The highly reactive double-anchor dyes are suitable for both the exhaust and the padding processes. Ecological limits for wastewater are satisfied as a result of a high degree of fixation and low salt requirements in the exhaust process, whereby the latter also has a positive influence on leveling. 

Exhaustion Process. In batch dyeing, the preferred mode depends on the type of dyeing equipment, the type of material to be dyed, and the solubility and affinity of the dyes. The dye is dissolved in hot water and added to the dyebath. The electrolyte is added either during heating of the bath or after attaining the optimum dyeing temperature. The material is dyed at 80-90°C. Exhaustion is completed, if necessary, at somewhat lower temperature for a short time. After the dyebath has been drained, the fabric is quickly washed clear with cold water and generally subjected to aftertreatment (see Section 4.3.4). 

In the dissolved form, the vatted dye is present as the sodium leuco compound, either as a single molecule or as a complex of a few dye molecules. In the exhaustion process, the higher the affinity, the more complete is the absorption by the fiber. The degree of absorption of dyes depends also on dye concentration, liquor ratio, temperature, and the electrolyte present in the dyebath. It is generally between 80 and 90 %. 

Batch Dyeing. Because of the low substantivity of leuco esters of vat dyes for cellulose, batch processes (exhaustion processes) are rather unimportant. 

Absorption of Dyes. In the exhaustion process, the dye is generally absorbed at 60-110°C in 30-60 min, and in the pad steam process at ca. 102-105 °C in 30-60 s. Dyeing with reducing agents is always performed by the exhaustion process. The fixing yield depends greatly on the liquor ratio. Optimal fixation and dye penetration are achieved with the pad roll process, in which the dye is applied from a concentrated liquor. 

Batch (Exhaustion) Processes. In jigger dyeing, the dyebath is charged with all the chemicals, and the dye and salt are added in steps at the desired temperature. After about six passages (or 60 min), dyeing is completed by rinsing and oxidation. 

Polyisoindolenines, which are high-molecular Phthalogen developers and are complexes of heavy metals and indolenine, are developed with reducing agents in a wet treatment. The polyisoindolenine complexes are fiber-affinitive and can be applied by using the exhaustion process. Their substantivity is low but can be increased by pretreating the cellulose with anionic products. Reductive development is performed in an alkaline medium with hydrosulfite. For details, see [82, 83],... 

Articles made of pure PES fibers are dyed almost exclusively in exhaustion processes. Disperse dyes are most stable at a pH of 4-5 (acetic acid). A dispersing agent is also added to the dyebath. Dyes sensitive to heavy metals (e.g., anthra-quinoid red products) are dyed in the presence of a complexing agent (EDTA type). 

Dyeing is performed mainly by exhaustion processes (batchwise). Another dyeing method with increased importance is the gel dyeing process. Dyeing in the gel state takes place during production of the fiber, i.e., after the fiber has been extruded and the solvent has been washed out, but before the fiber is stretched and dried (see Section 4.14.6). Continuous dyeing of stock, cable, and tops is also possible according to the pad steam process. 

Dyeing of Special Fiber Types with Cationic Dyes by the Exhaustion Process... 

We could look at every possible C-C carbonyl disconnection and decide which we prefer. For any even moderately complex molecule, this can be an exhausting process and we shall do it for just one target molecule. Thereafter we shall choose disconnections as we go along and go back to the target only if that strategy proves poor. Pratt and Raphael1 needed the keto-diester 1 for a synthesis of the anti-tumour compound vemolepin. Our first disconnection is easy as the a, 3-unsaturated carbonyl unit suggests the classic aldol la disconnection to 2. 

In closing, this paper was not intended to represent an exhaustive process development effort in flavors extraction from natural materials nor a development of the quantitative analytical capabilities of supercritical carbon dioxide. However, even though the examples and the conditions of extraction were somewhat arbitrary, they point out some of the interesting features of the pressure dependent dissolving power properties of supercritical fluids. They can be further refined by virtue of more narrow ranges and ratios of pressure and temperature to accomplish still more narrow separations. 

Riggins P H and Hauser P J, Exhaust process for simultaneously dyeing and improving the flame resistanceof aramid fibers , US Patent4,898,596,1990, assigned to Burlington Industries. 

Quaternary ammonium compounds are the next largest group of non-durable antistats. The most widely used are ditallowdimethylammonium chloride and dihydrogenated tallowdimethylammonium chloride (Fig. 10.2). These are common ingredients in laundry and dryer applied consumer softeners. Like many other cationic materials, cationic antistats have an affinity for textile fibres and can be applied by exhaustion processes. 

These finishes are applied in pad-dry or exhaust processes to almost all kinds of fibres, especially synthetics. Favoured articles include underwear, towels and bath mats that dispense body lotion, pantyhose that reduce cellulite, pyjamas and bed linen that ease neurodermitis, and shirts and other clothing that repel mosquitoes. The fixed chitosan capsules are described to be permanent for several cycles of hand or machine washing. 

Optical brightener for polyester and acetate fibers. HOSTALUX EBS-A produces a very brilliant white effect with a blue to blue/ violet cast. The product can be applied by both continuous and exhaust processes. 

Polyester OBA, good sublimation properties. May be applied by thermosol or exhaust process. Brilliant white with neutral/ green cast. 

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