Pigment dyeing is not really "dyeing" in it's truest form because the pigments stick on the fabric with the help of binders. Pigments are insoluble in water. They exist in the form of finely ground molecules, milled for garment dyeing purposes into a paste. When anionic dispersing agents are added, a slightly negative charge is present, thus the foundation for pigment dyeing is born. When a positively charged cationic pre-treat is added to the fiber a magnetic bond is formed. The process is complete when a cationic binder is added to "lock" the pigment into place. In pigment dyeing no actual chemical reaction takes place between the dye and the fabric.
Pigments are insoluble and are applied not as solutions but as finely ground solid particles mixed with a liquid. In general, the same pigments are employed in oil- and water-based paints, printing inks, and plastics. Pigments may be organic (i.e., contain carbon) or inorganic. The majority of inorganic pigments are brighter and last longer than organic ones. Organic pigments made from natural sources have been used for centuries, but most pigments used today are either inorganic or synthetic organic ones. Synthetic organic pigments are derived from coal tars and other petrochemicals. Inorganic pigments are made by relatively simple chemical reactions, notably oxidation or are found naturally as earths.
Scouring - Rinse - Index - Rinse - Pigment Dye - Binder - Rinse - Enzyme - Rinse - Softener - Extraction - Drying
3. Cationization Process:
Cationic polymers form a layer of cationic charges when applied to fiber surfaces.
Cationization of the fabric or giving electric charge to the fabric by a powerful cationic retreatment. Pigment dyeing is an electrical process whereby the goods to be dyed are given an electrical charge opposite that of the pigment. When the pigment is added to the bath, the opposite electrical charges attract each other, much like the north and the south poles of two magnets. Because of the electrical nature of the process.
4. Binder (Binding Process):
A binder used in the exhaust pigment dyeing procedure for fixing pigment colors. Binders are commonly acrylic polymers with nonionic and cationic nature. It improves crocking and wash fastness. After the pigment is exhausted , the binder is fed into the dyeing machine and exhausted onto the fabric over a period of time. Acetic acid is added to the bath, which facilitates binder polymerization, then the fabric is rinsed, the dyeing machine is drained, and the fabric is extracted.
5. Benefit of Pigment Dyeing:
a. Brilliant fluorescent colors.
b. Application to diverse kinds of fabrics.
c. Pigment process is faster than reactive dye.
d. Hi-low effects around the seam
6. Limitation of Pigment Dyeing:
a. Uneven dyeing effects.
b. Low crocking levels.
c. More sensitive to some fabrication, modal, rayon, etc.
7. Attention Points:
a. Different color if fabrications are different.
b. Thread would be dyed.
c. Label, print, accessories and trims would be dyed.
d. Low colorfastness to high temperature.
e. Neon and purple colors are poor in colorfastness.