What is the chemistry behind fiber reactive dyes?
Fiber reactive dyes attach permanently to cellulose fibers using a covalent (electron-sharing) bond. These molecules carry a “chromophore” which absorb varying spectrums of the light, allowing only certain spectrums to reflect. Covalent bonding is the one of the most basic and strongest types of chemical reactions.
What is dischargeable reactive dyes?
ovd dyes can be used in cationized dyeing processes, where only a surface deposition of the color on fabric is sought. During this process, which combines ovd dyes with a cationizing agent like fst ind new, garments are washed until they reveal an aged, yet clean, appearance.
What is fiber reactive dye and how does it work?
Fiber-reactive dyes molecularly bond with fabric, creating colorfast and long-lasting shades. They’re used on cellulosic fabrics such as cotton, linen, hemp, rayon and Tencel, and can also be used with wool.
What is remazol dye?
Remazols are reactive dyes suitable for dyebath, printing and painting on Cotton, Rayon and other regenerated cellulose materials. Remazol dyes will also dye Silk and Wool in a HOT dyebath with a weakly acid pH of 4.5 to 5.0.
What pH is required for dye bath set for reactive dyeing?
4.5-5.0
DyStar recommend dyeing conditions of 30 mins at 110 °C and pH 4.5-5.0 (Figure 2.), the dyeing temperature being 20 °C lower than that for PET fibres.
Why is reactive dye carried out in two steps?
Hydrolysis of reactive dye: This reaction of dye with water is known as hydrolysis of reactive dye. After hydrolysis dye cannot react with fibre. So hydrolysis increases the loss of dyes. This hydrolysis occurs in two stages.
What is the main chemical used for discharge dyeing?
The most familar discharge agent is ordinary household bleach, whose active ingredient is sodium hypochlorite. It will remove or change the color of many dyes, but not all dyes can be bleached.
What is the temperature and pH during dyeing with reactive dyes?
Factors to Be Considered During Reactive Dyeing pH – Strong alkaline pH is required ranging from 10.5-11.2. Temperature – Dyeing temperature depends on the brand of dye used. Concentration of electrolyte – The depth of shade is the determining factor of electrolyte concentration. Time – Ranges from 60-90 minutes.
What is cold brand reactive dyes?
Cold Brand Reactive Dyes are a class of highly colored organic substances, primarily used for tinting textiles, which attach themselves to their substrates by a chemical reaction that forms a covalent bond between the molecule of dye and that of the fiber.