Textile Dyeing Chemicals; can be defined as Textile Auxiliaries used in textile dyeing.
Textile Auxiliaries refers to substances that have been specially developed by chemical companies for textile processes, whose chemical structures are somewhat complex, and most of them are in the form of mixtures. The term Textile Chemicals, on the other hand, refers to substances such as some organic and inorganic acids, bases, salts used in Textile Processes with certain chemical structures.
Wetting agents are substances that provide good wetting of textile products. Dye and Printing processes are wet processes. Therefore, in order for the material to be well treated, it must first be well wetted.
Wetting agents generally used in the textile industry
- Anionic wetting agents
- Cationic wetting agents
- Nonionic wetting agents
- Amphoteric wetting agents
The most important ones are Anionic and Nonionic types.
- a) Nonionic Wetting Agents
The most suitable Wetting Agents for Chemical Cleaning and Wetting are the Nonionic types exemplified by the alkyl phenol ethyleneoxide condensation products series. These types of Wetting Agents can be dissolved in water as well as in oils.
Noniphenolethyleneoxide condensate, fatty alcohol ethylene alcohol condensates and fatty alcohol condensates are nonionic wetting agents.
The distinctive feature of Nonionic Wetting Agents is that they are sensitive to temperature. With the increase in temperature, the dissolution of nonionic wetting agents changes inversely. Nonionic Wetting Powers have the best wetting power at the point just below the point where the solubility stops. If the temperature at the saturation point of the solubility is exceeded at an appropriate stage, the wetting agents that become insoluble in water remain on the dyeing product. This will improve the absorbency and rewetability of the product. Nonionic wetting agents, which have good emulsifier properties for oils and waxes on the product, also have good washing properties.
- b) Anionic Wetting Agents
Wetting agents such as Turkish red oil, Dodecyl, Benzene sulfonate, Dioctylsulfosuccinate are the main anionic wetting agents. Anionic Wetting Agents are substances that contain charged active groups such as carboxyl, sulfate, sulfonate, and phosphate, which form the hydrophilic part in their structure.
Emulsification, Dispersion, Wetting and Cooking properties of phosphate based wetting agents are quite good.
- In order for the chemical substance to be used as a wetting agent;
- It should have good wetting properties.
- It should not foam
- Should have a good cleaning effect
- The resolution should be very good
- Must be resistant to acids and alkalis
- Must be resistant to reducing and oxidizing substances
- Must be resistant to high pressure and heat
- Emulsion and dispersion ability should be good
- Fiber affinity should be good
- Should be in a structure that is compatible with all kinds of dyestuffs.
- Should impart a good hydrophilicity to the applied material.
- Should have a good storage life.
Dispersing Agents
They are substances that allow very small particles to remain in a more or less uniform and stable suspension in a given matrix. In other words, they are substances that facilitate the dispersion of particles or stabilize dispersions.
Dispersing Agents are substances that provide homogeneous distribution of water-insoluble solids in water, prevent the formation of aggregation (solidification) and help the insoluble matter to remain at the desired level of dispersion in the liquid.
Dispersing Agent Types
The three main groups of substances that can be used as Dispersing Agents are;
- Water-soluble Polyelectrolytes of most anionic types
- Anionic and Nonionic type Surfactants
- Polymers
These compounds make the Paint easily dispersible in water, thus keeping it stable throughout the applied process.
Thermodynamically, the dispersion of colloids (Dye Dispersions) is in a metastable state, prone to segregation or coarsening of particles.
Coagulation, Coalescence is the coarsening of particles or deterioration of dispersion. In dyestuff chemistry, coarsening of particles is defined as Aggregation and Agglomeration. The dispersing agent and protective colloids prevent such coarsening by forming elastic protective layers around the particle and thereby stabilizing the dispersions.
The greater the pushing force of a disperser than the pulling force, the better the dispersing property of that disperser. Dispersing agents can be considered as one of the main products of Textile Dye Chemicals.
Levelers ( Leveling Agents )
They are substances that allow the paint to be distributed uniformly on the product. Uniform dyeing is achieved by prolonging the dyeing time. Dyeing Process is an equilibrium process as in a reaction. It can be affected by adding temperature, pH, dyeing method and proper dyeing agent. The Auxiliary Agent reduces the drawing speed of the dye and distributes the drawn dye evenly on or inside the fibers. The effect of the smoothing agent depends on the temperature, the concentration of the dye and the auxiliary depends on the iteration, the time factor is limited by the rentability.
Since the Leveling Agents are Surfactants, they are structurally Anionic, Cationic, Nonionic or Amphoteric.
Migration Inhibitors
Most of the Textile Printing and Continuous Dyeing processes are characterized by the use of auxiliaries that increase the viscosity of the application medium. The purpose of this is to facilitate and stabilize the local application of color. Such Textile Auxiliaries are known as thickeners in printing and as Migration Inhibitors in padding processes.
Such substances are characterized by significant macromolecule swelling due to solvation in solution.
Migration inhibitors are used to thicken padding solutions in continuous dyeing processes.
Some of the substances used for this purpose are
- Polysaccharides
- Alginates
- Guar and Xanthate gums
- Modified starches
- Celluloses
The most widely used of these substances are Alginates. Concentrations in Continuous Dyeing are much lower than those used in printing. Because the Dyeing Process requires lower viscosity to allow the solution to easily penetrate the fabric during padding.
In addition to Alginates, Polyacrylates, Polyacrylamides and Polyethoxylates are also used. The result is mixed polyglycolesters of fatty alcohols with ethylene oxide or propylene oxide. In other words, they are non-ionic block copolymers and function due to their low cloud points (25ºC).
Carriers
The literal meaning of Carrier is Binding. Carrier generally increases the dyeability of polyester during dyeing of polyester.
Effect of Carriers on Dyeing Polyester
Carrier passes around the fibers as a film, Dispersion Dye dissolves in the carrier and thus quickly penetrates into the fiber. The dye and the carrier form a loose complex, which is then more easily attracted by the fibers. It improves the water solubility of Carrier dispersion dye and thus increases its affinity by the fibers.
Required features in carriers
- High effectiveness depends on the nature of the dyestuff and less on its concentration. Concentration of carrier is important in dyeing.
- Should be able to emulsify easily and remain as stable as possible in emulsion. It is generally recommended to use after the carrier emulsion has been prepared. Stain occurs due to deterioration of the emulsion.
- Should have little evaporation feature. After the carriers evaporate, they condense and drip onto the product again, resulting in stains.
- Should not have an offensive odor. Normally every carrier has a more or less characteristic odour.
- Should not cause shrinkage and wastage of the fiber.
- In the dyeing of special wool and its blends, the dyestuff attached to the fiber should not be removed by removing it.
- Should be easily removed from the fiber.
- Should not have a toxic effect.
- The dyeing bath should not adversely affect the properties of the dyestuff and the strength of the printing paste.
- Should be economical.
Textile Dyeing Chemicals are chemical Auxiliaries that are generally used after the Pre-Processes are completed.