basic about dyeing process and dyes

1. POWER POINT
PERSANTATION
TECHNOLOGY OF
DYRING – 2
By- Hemant yadav
textile processing

2. DYEING :-
It is defined as the single colour , uniform
coloration of whole fabric is known as
dyeing
Dyes are water soluble or insoluble .
Insoluble dyes make soluble by using some
chemical .

3. Classification of dyes:-
Dye
Water soluble water insoluble
direct dye vat dye
reactive dye Sulphur dye
acidic dye disperse dye
basic dye
sol. Vat dye

4. Topic :-
*Acid dyes –properties ,method ,
application and mechanism
* Basic dyes -properties ,method ,
application and mechanism

5. Acid dyes :-
It may be defined as the dyes which are applied in acidic
medium or presence of acids.
Two type of acids
1)Mineral acid –
HCL-Hydrochloric acid, H2SO4 – Salphuric acid
2) Organic acid –
CH3-COOH - Acetic acid, HCOOH- Formic acid

6. Gernal structer of acid dyes:-
R -So3Na
R- SO3 Na
( dye ion)

7. Properties of acid dyes:-
1) These are applied in the presence of acid like
mineral or organic acid . So it is called acid dyes.
2) These are water soluble dyes . Due to presence
of sol. Group - -So3 Na , - So3H
3) Fastness property depend upon chemical
structure . Metal complex dye having good fasness
property.

8. 4) These are simple to apply
5) These have good brightness property
6) These are economical dyes
7) These are not costely

9. Method of dyeing:-
Material required for acid dyes-
1) Colouring matter
2) Acid -( according to class of dye )
3) wetting agent – (spreading the dye particle to
whole fabric )
4) Electrolytic – NaCl , Na2So4

10. 5) Dispersing agent
6) Levelling agent
7) Chelating agent – these are remove to hardness
of water
ex-- EDTA- Ethylene diamine tetra acetate
8) Oxidising agent – oxidising agent like (KMno4 )

11. Mechanism of wool with acid dye:-
Wool fiber is chemically represented by –
H2N – W--COOH
(Amine group) (Carboxyl group)
When dye solution is mixed with a strong acid .dye
and acid brakes in ion .when wool is entered in this
bath following reaction takes place.

12. HCL H CL
R-So3Na R- SO3 Na
H2N – W--COOH
H2N – W--COOH

13. Basic dyes:-
Property –
1) Basic dye are positively charged ion.so there is
also called cationic dyes.
2) Basic dye are applied on acrylic wool.
3) These give very bright shades.
4) These are sensitive to acids.

14. 5) These have good affinity for wool.
6) These dyes are dissolved in the presence of acid
(Acetic acid).But generally insoluble in water.
7) Cellulose fibers have no affinity for basic dye.
8) Basic dyes can be applied to Cotton , Silk with
mordanting.
9) Mordant have affinity both for fibre and dye.
10) Jute is also dyed in a similar way of basic dye.

15. Application on cotton :-
Basic dye can be applied on cotton fiber with the
mordanting
Mordant:- A mordant is a chemical which act as a
bridge b/w. Basic dye and cellulose fibre.
1)Tannic acid:- Tannic acid was used as mordant
before dyeing with basic . After this fixation with
antimany is required so it gives a long process.

16. 2) Synthetic mordent:- Synthetic mordants do not
require any after fixation . These are easy to apply.
For example:- Katanol - o (Bayer)is a substitule of
tannic acid . It is soluble with soda ash (Ha2Co3).

17. Procedure:- it has two steps
1) Mordanting of cotton :-
cotton is treated with katonal-o (2-6%) dissolved is
soda ash at boiling .
katanol – o mordant --- 3 part
Soda ash --- 2 part
Material is entered in this mordant solution
at 70-75 C and treated for 2 hrs .

18. Dyeing of cotton :-
Material is neutralized with 1% acetic acid to
neutralized soda ash.
Set the dye bath with basis dye dissolved with acetic
acid .
Start dyeing at 60 c and raise the temp to boil 30
minutes .

19. Dyeing Recipe:-
dye - x gm
Acetic acid - 2 - 3
EDTA ( sequestering agent ) - 0.5 - 1%
Temp - Boil
Time - 60 - 90 minutes
Dye for 60 – 90 minutes . Then should not be used for
preparing dye solution.

20. Mechanism of bold dyeing on
cotton :-
Due to the application of mordant an anionic (- ve )
site is created on cotton . Basic dye cation (+ ve )
charge ion is attracted on this (- ve ) site on cotton
and so the cotton fiber get dyes by basic dyes with
the help of mordants .

21. Acid mordants dyes
– Acid mordants dyes are also acid mordant are used with these dyes so these
are called mordants dyes so these are called mordants dyes .chromium salt
like potassium dichromate sodium chromate are used as mordants also called
chrome dyes .
– Properties :-
– (1) These dyes can makes complex molecules with heavy metal atoms .
– (2) Fastness to washing is good .
– (3) Fastness to rubbing is good .
– (4) Fastness to chlorination is good
– (5) These are similar to acid dyes .

22. Method of dyeing
– There are three method of dye of acid mordant dyes method
– (1) Pre chrome method
– Mordanting with chrome before dyeing
– (2) After chrome method
– Mordanting with chrome after dyeing
– (3) Meta chrome method
– Mordanting with chrome during dyeing

23. – Pre chrome method or chrome mordant method :-
– It is a two bath process applied in 2 step
– 1st step :-pre mordanting of wool and silk with potassium dichromate sodium bichromate
– Bath is set with
– Potassium dichromate -1-3%
– Oxalic acid /formic acid – 1-2%
– Start temp. - 60 c raised to boil
– Mordanting time - 60-90 min.

24. – Second step :- set the dye bath at temperature of 60 c dissolve the dye properly and
enter the pre mordanted wool in the dye bath .dye for 30 min. raise the temperature to boil .then
dye for 60 – 90 min acid 5% potassium dichromate in bath to improve washing and milling
fastness dye for 30 – 40 min . Finally material is not wash soaping and cold washed
– Disadvantages:- require more water ,space ,time & labour
– (B) After chrome method :- As the name suggest this is also a two bath
process but the steps are reverse then the pre chrome method .
– Step (1) :- dyeing with dye solution
– Set the dye bath ,as in acid levelling dyes with

25. – Dye stuff - x gm
– Acetic acid – 3-4 %
– Glauber's salt - 5-10 %
– Leveling agent – 1-2 %
– Start temperature 50 c . Dye for 30 min add dye in two instalment .raise the temp to boil again
dye for 45-60 min give more time to completely exhaust . The dye bath by adding 5%
ammonium sulphate (acid liberating agent )cool the bath to 70 c
– Step -2 :- Mordanting of chroming
– Add 1-2%potassium dichromate (pre dissolved) in the dyeing bath and raise the temperature
up to boil in 30 min chroming treatment is carried out for 30-45 min

26. – Disadvantages :-
– (1) Accurate shade matching becomes difficult due to after mordanting
– (2)Two both process so need more water , time and etc.
– (c) META CHROME METHOD :- This is a single bath process . In tis method
mordanting and dyeing are carried out In the same bath at the same time.
– Dye bath recipe :-
Dyestuff – x gm
Glauber salt – 5.0%
Levelling agent – 1-2 %
Chrome mordant – 2-5 %

27. – PROCEDURE
– Set the dye bath with pre dissolved dye at 50 – 60 c temperature .run the maintained for 15 min
.add chrome mordant in dissolved from in this dyebath raise the temperature to boil and dye for
60 – 90 min for medium dark shade acetic acid Acid may be added (0.5-1%)
– Advantages :-
– (1) It is a single bath process .
– (2) Less water space , time and labour is used as compared with other methods .
– (3) Feel of the material is better .
– (4) Easy to dye .
– (5) Most popular process of dyeing wool /silk

28. – Metal complex dyes :-
– These are structurally modified acid dyes in which metal atom (chromium or cobalt ) has been
already in corporated in in the dye molecule . So no pre or postchroming is required . A metal
complex is already present in the dye
– Types :- These are two type of metal complex dyes .
– (1) 1:1 metal complex dye
– ( mixture of 1 atom of dye with 1 atom of metal )
– (2) 1:2 metal complex dye
– ( mixture of 2 metal of dye with 1 atom of metal )

29. – Properties :-
– (1) These are water soluble dyes .
– (2) High fastness properties .
– (3) Simple dyeing method .
– (4) Give brighter shades .
– (5) Good migration properties .
– (6) Excellent ,washing light rubbing bleaching fastness .

30. Pthalogen blue /Alcian blue dyes
– Pthalogen blue dyes give puse and brilliant
peacock blue shade and Alcian blue Dye give
brilliant turquoise/ green shades. These are
widely used for ladies dress goods, school
uniform. Their fastness properties are also
good.

31. Properties
– 1. Pthalogen blue dyes are formed in side the cellulosic fiber as
metal –complex salt as copper thalocynine.
– 2. These are used as insoluble pigments for ground shade in
blue/Green /peacock shades .
– 3. On solublisation of CPC (by introducing sulphonium group in the
CPC molecule) Alcian blue Dyes are produced which has affinity for
cellulose.
– 4. On addition of sodium carbonate solublising group is removed
and Dye becomes insoluble agent as CPC pigment.

32. Principle
– Pthalocyanin pigment are blue pigment formed by passing
ammonia in to molten ptha ice Anhydride in an iron vessel
the blue pigment appeared as an impurity and it separated.
This led to the discovery of CPC pigments copper.
Pthalocyanin was formed in a similar why by ICI .
– Alcian blue Dye are for me by introducing a solublising group
in the CPC structure and later on fixation by alkali which
convert the soluble CPC in to insoluble blue pigment.

33. Application procedure on cotton
– Pthalogen and Alcian blue series of dyes was introduced
by ICI company (Indian chemical industries ).Alcian blue
GXS is suitable for producing very bright yellowish green
shade.

34. Procedure
– 1. A stock solution of Alcian blue Dye is prepared as
Alcian Dye - 50 parts
Acetic acid - 15 parts
Water - 100 parts
paste the contents properly and add water at 30-40 C to make 1 litre .
2. Dye bath is prepared by adding dyestuffs .Run for 5-10 minutes
at 30C. Add non-ionic auxiliary like lissamine –A (1%) to achieve
uniform dyeing .Run for 5-q0 minutes at 30C.

35. – 3. Temperature is raised to 95C over 20 minutes .Run for 30
minutes .
– 4. Dyestuffs is then fixed by soda ash -5 gm/ltr at 95C and
material is run for 10-15 minutes.
– 5. Finally shaping & washing is done to remove alkali and other
chemicals from the fabric.