Textile Pigments - Dyes

2 views
Skip to first unread message

Furkan Bekyol

unread,
Apr 11, 2022, 4:30:02 AMApr 11
to Textile Pigments

Pigment is a substance in particulate form which is insoluble in water but which can be mechanically
dispersed in this medium to modify its color and light scattering properties. They are organic or
inorganic colouring materials.
Pigments have no direct affinity to textile fibers. They are fixed on textile materials (fabric/yarn) with
the help of a binding agent in form of a this invisible coating.
In pigments auxochrome groups are absent. A number of organic pigments are prepared from dyes
by combining the dyes with a dye precipitant.
Pigment are abundant in nature. The cause of color is not only the light absorption of molecules but
also the purely physical effect of optical diffraction at grating systems. Pigments are applied at
thickened textile pigment coating from oil-in-water or water-in-oil emulsion systems.
Properties of pigments:
i. It is insoluble in liquids but can be mechanically dispersed in the medium.
ii. Pigments have no direct affinity towards fiber, so binding is used as a binding agent in
case of pigment colouration which sticks the pigment particle on the fiber surface.
iii. Pigment are applicable to all kinds of fibers.
iv. No aftertreatment is required after coloration process, only drying and curing are required.
v. Only rubbing fastness of pigment colouration is poor, but water wash and light fastness
are very good.
vi. A wide range of bright shade can be produced by pigments.
vii. In pigments auxochrome groups are absent.
Differences between dyes and pigments:
The difference between dye and pigment is not a clear one. Most organic pigments are closely related
to dyes with respect to their chemical structure. There are dyes which become pigments after
application. Vat dye is a dye when used in dyeing, when vat dyes are oxidized and made insoluble in
fabric(after vatting) that is called pigment form of vat dyes. Vat dyes act like pigment when used in
printing. Now some differences are mentioned below:

1 ) The basic difference between dye and pigment is that, dye has three parts-
i. Chromophore, which is responsible for color.

ii. Auxochrome, which is responsible for dye properties
iii. Chromogen, which holds the above two together.
But pigment has two part:-
i. Chromophore, i.e. color bearing part.
ii. Chromogen.
2 ) Pigments are insoluble in the materials that they are used to color, whereas most dyes are soluble
in them.
3 ) pigments are water insoluble, but dyes are more or less water soluble.
4 ) Pigments are used as colorants in the physical for in which they are manufactured. But dyes are
first dissolved in water to form a dyebath, then they diffuse as single molecules from these solutions
into textile fibers to colour them.

5 ) Pigments have no direct affinity towards textile fibers but most dyes have that.
6 ) Pigments are metallic compounds may be organic or inorganic. But dyes are mostly organic
compounds, few are inorganic.
Classification of pigments:-
There are mainly two types of pigments, namely,
1. Organic pigments and
2. Inorganic pigments
Organic pigments are further classified as below:-
I. Dyes converted into pigments.
It has two types,
1) Reactive Dyes made insoluble by precipitating on substrates.
2) Vat dyes converted into pigments
II. ISO indolinone pigments
III. Azo pigments:
It has two types
1) Metal free{Water insoluble azo compounds (group1)}
2)Metal containing
there are two types: chelates(group-3) and
Water soluble azo compounds(group-2)
–low soluble, make heavy metal salts(group-2a)
–high solubility precipitate heavy metal salts or basic substrates(group-2b)
IV. Quinacridone pigments
V. Phthalocyanine pigments
Inorganic pigments are classified by two types
I. White pigments and
II. Coloured pigments
There are three types of coloured pigments:
1. Ultramarine
2. Cadmium pigments and
3. Iron oxide pigments.
Reply all
Reply to author
Forward
0 new messages