Direct dyes liquor ratio

For environmental reasons, other attempts have been made to reduce the amount of conventional electrolyte added. Lowering the liquor ratio will in itself reduce the amount of electrolyte required. In one commercially feasible system [72], a range of direct dyes was successfully screened to select members that could be applied efficiently to give 95-100% exhaustion using significantly less electrolyte than usual. Thus at applied depths up to 2-3%, only 2-5 g/1 salt is required navy and black dyeings can be produced with only 7.5-10 g/1 salt compared with the conventional 25 g/1 addition. 

In another method [30] fabrics treated with several concentrations of NaOH are immersed in a mixture of 1.3 g/1 Telon Fast Red AF-3G 150% (BAY), a low molecular weight acid dye, C.I Acid Red 151 and 1.4 g/1 Benzo New Blue GS 140% (BAY), a large molecular weight direct dye, C.I. Direct Blue 10, liquor ratio 70 1 at pH 2 using H SO for 10 min cold followed by washing off. Untreated cotton is stained red and becomes progressively bluer with increase in NaOH concentration. 

In order that the liquor ratio may remain constant, the dyeings and the migration tests should be carried out in conical flasks with a reflux condenser, or a simple device such as is shown in I ig. 16.5 has proved very useful. The classification of many of the direct dyes is given in the Colour Index of the Society of Dyers and Colourists, and it is now usual to give this information in the dyestuff manufacturers catalogues. 

All of the dyeing was carried out in a Ahiba Turbo Color at a 1 30 liquor ratio with 1% direct dye, C.I direct 225, on weight of fabric for 60 minutes. The dyeing was monitored on a system with on-line monitoring and automatic calculation of the exhaustioa... 

Armfield W., Boulton J., Crank J. (1956), II - The Effect of Liquor Ratio on Direct Dyeing Journal of the Society of Dyers and Colourists, 72,278-86. 

A bypass pipe connection may be used to isolate the mixing tank from the rest of the dyeing vessel in this way low liquor ratios can also be established. The fluid flow loop through the pipes, however, can be controlled by means of pneumatic valves that direct the fluid from inside to outside, or vice versa, of yam packages. This may be done with the aid of a four-way valve located at the base of the kier. A ventilator valve may be used to direct the liquid in the top of the kier to the mixing tank, and once the kier is full this valve is shut off. Valves may be controlled manually via a control box or via connections to the interface, which in the example in Table 7.2 are BlTs 0-5 of PORT B. All pneumatically operated ball valves on the machine may be fitted with doubleacting actuators. The actuators may be controlled by solenoid/spring spool valves (e.g. 5/2). The term 5/2 denotes a valve with five ports and two positions. 

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