Pigment dyeing is a comparatively recent addition. In
the process of pigment dyeing no actual chemical reaction takes place
between the dye and the fabric. Instead, what happens is that the
pigments gets seated on the fabric with the help of binders. There is
a challenge in pigment dyeing. Pigments are not soluble in water and
shows no affinity for fiber. So, conventional dyestuff-based dyeing
conditions are not feasible for pigment dyeing. To come to terms with
such limitations, a new kind of pigments have been formulated for use in
fibers. These are maintained in a stable dispersion in the medium of
water by anionic surfactants. This type of pigment is known as pigment
resin color (PRC), primarily used in printing. Some of the popular
pigments used in fabrics are given here.
- Yellow colour: Acetoacetic acid anilide pigments
- Red: Azoic pigments
- Blue or green: Phthalocyanine pigments
Difference between a dye and Pigment in context fiber dyeing is
explained in the following section.
Pigments |
Dyes |
Pigment coloring is done by dispersion of fine
particles. These are in sizes smaller than 1 micron. They contain
around 108 mol of molecules per particle. They get attached to the
fibers in this original state. |
In contrast, dyestuffs tend to fix on fiber with
individual molecule (in some cases, however with several molecules) |
A good pigment dyeing system should ideally come with
the follow innovative features.
- Doing without wet processing: results in Preventing water
pollution along with high Productivity.
- Binder: For improving crock fastness
- No thermo-migration : This makes even dyeing on both the sides
- Excellent Fastness properties
A typical process of pigment dyeing for cellulosic
textile materials consists of padding the textile materials with a Dye
bath. The dye bath contains anionic or neutral colour dispersions of
pigments. Along with the pigments it also contains anionic binders,
acid-liberating catalyst, anti-migrating agents, and other types of
additives. Then the textile materials are dried at high tempratures,
this cures the film-forming binders and pigment colours firmly on the
textiles.