- •T. J. Djankova, a. A. Burinskaja, s. A. Zakharenkov technology of finishing textile materials
- •1. Principal views of textile fibers
- •2. Preparation of cellulose materials for dyeing and printing
- •2.1. Bleaching of cotton textiles
- •2.2. Mercerization
- •3. Application of optical bleaches
- •3.1. Optical bleaching substances
- •3.2. Test on presence of an optical bleach
- •4. Dyeing
- •4.1. Technical classification of dyes
- •4.3. Mordant dyes
- •4.4. Acid metalline dyes
- •The abovementioned recipe and procedure of dyeing are standart and can be changed and specified according to type of the equipment and also kind of coloring material.
- •4.5. Direct dyes Direct dyes may be used for dyeing cotton and other cellulose fibers. Direct dyes simple in application, are suitable for dyeing on any equipment, well combined with each other.
- •4.6. Reactive dyes
- •4.6.1. Cellulose dyeing. Batch methods of dyeing
- •Table 4.1. Dyes Bath Composition and Dyeing Conditions
- •4.6.2. Continuous dyeing
- •4.7. Cationic dyes
- •Dyeing by fast-fixing dyes
- •Dyeing of newly-formed braid
- •4.8. Disperse dyes
- •4.9. Vat dyes
- •Indigo-molecular structure Vat Yellow-molecular structure
- •Dye. . . . . . . . . . . . . . . . . . . . . .3 % from weight of a fiber
- •4.10. Sulfur dyes
- •4.11. Azo dyes synthesized in the fiber
- •5. Printing
- •5.1. Reactive dyes printing
- •5.2. Pigments printing
- •5.3. Thermoprinting of fibrous materials
- •6. Final finishing
- •6.1. Giving to fabrics of properties of water pushing away
- •6. 2. Giving to textile cloths of oil- hidrofobization
- •6.3. Giving to fabrics of fireproof properties
- •6.4. Giving to fabrics of anti-shrinkage chemical properties, form-stable finishing
- •Application Rules
- •7. Dyeing from Emulsions
- •7.1 Auxiliaries solvents
- •7.2 Emulsifiers
- •7.3 Dyeing with water-soluble dyestuffs.
- •7.4. Basic dyeable synthetic fibers
- •7.5. Physic-chemical fundamentals of emulsion technique
- •Influence of the temperature on the stability of an emulsion
- •Influence of additives on the stability of an emulsion
- •The optical properties of a water/perchloroethylene emulsion
- •Vapour pressure of a water/perchloroethylene emulsion
- •7.6 Equipment for dyeing from organic solvents
- •8. Equipment for dyeing and finishing factories.
- •8.1. Machine for washing, bleaching and dyeing “colorado”
- •8.2. Мachine «petra» f. Biancalani For obtaining effects of “worked surface”
- •8.3. High temperature machine mcs comby jigger
- •8.4. Hydraulic drying cylinder machines “jigger jht” by exclusivas tepp s.A. (Spain)
- •8.5. Vertical high-temperature high-pressure yarn dyeing plant
- •8.6. Flow line for combined bleaching and dyeing of fabrics лкб-140
- •Specification
- •8.7. Rapidstretch
- •8.8. Technodye rapid system Main features.
- •8.9. Superflux ne
- •Finally
- •8.7. Rapidstretch 84
7.1 Auxiliaries solvents
Auxiliaries solvents are often used to prepare pastes and liquid dyes. Co solvents can be emulsifiers, hydrotropic agents or solvents immiscible, or only upon the speed at which the equilibrium is adjusted. For example, dyestuff which is only present in the aqueous phase when dyeing begins, can also be dissolved in the organic phase at the end of the dyeing operation.
The water-soluble dye is dissolved in water, if necessary with the help of a co-solvent, and the resulting aqueous solution is emulsified into the PCE with the aid of an emulsifying agent. The dyestuff, which is soluble in PCE but insoluble in water, is dissolved in PCE, if necessary with a co-solvent, and the amount of water required for dyeing is emulsified into the PCE with the aid of an emulsifying agent, if necessary.
The main difference between a dispersion of solid particles and an emulsion, however, is that an emulsion is thermodynamically less stable than dispersion and is more easily changed during the dyeing process. The dyeing mechanism during aqueous disperse dyeing is based on low solubility of the dispersed dye in the aqueous phase. Dyeing from emulsified droplets is effected by adsorption of the emulsified droplets at the fiber surface. The levelness of the dyeings is therefore largely determined by the relative movement of the liquor and the fineness and homogeneity of the emulsion. PCE /water emulsions have an azeotrocic boiling point of 87 °C. The vapour phase contains more water than the liquor (liquor: 0,5-3 %; vapour: 1 6 %). Hence the aqueous phase partly miscible with water. Co-solvents are used in the preparation of highly concentrated dyestuff solutions miscible with water or with PCE. The use of co-solvents which enhance the water-solubility of a water-soluble dye, makes it possible to accommodate the necessary amount of dyestuff in a smaller quantity of water than normally required. This is of decisive importance for ail dyestuffs with a water solubility of less than 70-100 g/l. This concentration can only be attained with the aid of a co-solvent; alternatively the water content of the emulsion must be increased. Hence the use of co-solvents makes it possible to release liquid brands which offer advantages in application.
On the other hand, co-solvents involve additional cost, recovery problems, and problems in respect of stability of the emulsion.
Co-solvents can also be used in the preparation of liquors based on solvent-soluble dyes. Such dyes are often insufficiently soluble in 100% PCE, or they are produced in the form of organic solutions.
7.2 Emulsifiers
Anionic, cationic and non-ionic emulsifiers are suitable for preparing water/ PCE emulsions with PCE as the external continuous phase. The suitability of an emulsifier for this purpose depends not only upon its emulsifying properties, but also on its influence on the dyeing mechanism.
The absorption performance of a dye-stuff is generally different when using water or PCE emulsion. The performance will also vary according to the kind and quantity of emulsifier used. Some emulsifiers show an interaction between dyestuff and fibеr and can therefore be considered as dyeing auxiliaries.
The required amount of emulsifier depends on the water content of the solvent and on the degree of agitation of the machine. The emulsifier quantity can be calculated in relation to the weight of the goods and in relation to the liquor. Calculation on the weight of the goods is preferable since it enables a direct relation to the amount of dyestuff used. But it is not possible to state a definite relationship between dyestuff, water and emulsifier, since most machines have a "blank" value. Hence it is riskier to transmit a given recipe from one dyeing apparatus to another, than in the case of a purely aqueous dyeing, as long as the emulsion is not a physically clearly defined system.
The economy of dyeing from emulsions depends on the required amount of emulsifier. The amount of emulsifier can be reduced to as much as 2% in relation to the weight of the goods when using the solvent dyeing machines and solvent drum dyeing machines which are now on the market.
This means the auxiliary costs in emulsion dyeing approach the level of the auxiliary costs when dyeing from an aqueous bath. If machine conditions are suitable, 40 parts water can be emulsified into PCE with the aid of 2 parts emulsifier under normal dyeing conditions. It is, therefore, possible to produce 2-4% dyeings on the basis of water-soluble dyes without using co-solvents. The emulsifier content increases with decreasing agitation for given water content of the liquor. To stabilize an emulsion which is not moved, it is generally necessary to use an emulsifier/water ratio of 1:3 to 1:4.
It would be unrealistic to transfer such laboratory recipes to bulk dyeing, since they correspond to an emulsifier requirement of 10% in relation to the weight of the goods. An emulsifier content of this order of magnitude will affect not only the light fastness, but also the liquor exhaustion and wet fastness.