basic about bleaching of various fiber like cotton wool silk

1. TECHNOLOGY OF
BLEACHING – 2 By-Hemant yadav
Textile processing

2. BLEACHING
bleaching is a process in
which remove the natural
colour and give extra
whiteness to textile
material

3. Before bleaching processes :-
* Singing
* Sizing
* Desizing
* Scouring

4. Topic :-
*Impurities in wool
*Carbonising processes for raw wool and
woolen fabrics
*Scouring of wool in loose form
* Machines for using scouring of raw wool

5. Impurities in wool:-
Raw wool contain 40 to 50 % of impurities. It may contain 40 to
50% wool grease.
Compared with cotton 0.5 to 1% oil and wax in cotton
Wool also contain natural oil and fats dirt etc. wool remove from
dead skin . Also contain lime, Which creates difficulties
In scouring with soap & soda (soda ash )

6. wool fat or grease :- grease is removed in emulsion
scouring
suint :-suint is water soluble it is removed by washing
such wool should be given a treatment with dilute HCL
(hydro chloric acid). Impurities ,such as “suint” consist of
potassium salt are removed by treating with luke warm
water

7. Carbonizing process :-
Wool carries lot of vegetable matter called “ burrs” . These are
removed in worsted industry in loose state while in most carbonizing
process is done on piece goods. The process of carbonizing consist in
treating wool with mineral acid or acid salt ,drying .
The vegetable matter gets tendered being changed into
hydrocellulose and is removed by shaking the goods
Sulphuric acid of about 9* tw is used and time of absorption is about
2-3 hrs. drying is done at 90*c.take material and wash thoroughly.

8. steps of carbonizing process :-
Treat material with sulphuric acid (9tw)for 2-3 hrs
dry at 90*c
Shake in a shaker
wash thoroughly with water

9. Scouring of wool in loose form:-
Due to felting property of wool , scouring of wool in loose state is
done. The most common machine is “harro fork”machine ,which
machine consist of several compartment each with a pair of
sqeezinge roller and having on overhead arrangement with long
forks which is given a to and fro motion pussing the loos wool
forword loose wool is fed on a lattie belt conveyor after last
squeeze much cleaner wool is deliverd on a similar lattice
conveyor removal of suint and wool fat along with dirt etc.

10. Swing rake machines :-
Wool is feed on to a lattice and it is then conveyed through the
bowl containing scouring liquor by a series of rakes ,
Rakes are operated by a crank motion .the machines are
constructed with three or four bowls and last one is used for
runsing with cold water

11. Diagram of swing rake machine :-
A -feeding conveyor
B -swing rack
C -crank
D -bowl with
perforated flask
bottom
E –sediment outlet
F –output conveyor
G –squeeze roller

12. (1) The first two bowls are used for scouring
(2) Last bowls is used for rinsing with cold water
(3) There may be seven to ten rakes per bowl working at a speed
of six to fourteen strokes per minute .the wool passes through a
pair of squeeze roller between one bowl to other.
During its progress through the machine wool moves over a
perforated false bottom . This permits the dirt to fall through into
the setting compartment each bowl except last is filled with
scouring liquor contaning soap and soda and temperature is
brought to 35* to 40*C.

13. Harrow machines :-
It consist of four or five bowls arranged in sequence so that wool
passes directly out the machines consist of long through provide
with rakes a false bottom and at the exist a pair of squeeze roller
the takes have a recipracating movement which makes wool travel
forward as wool leaves the excess of soap liquor is squeezed ,wool
passes to second bowl ,where it eceiver further scouring in the
final through wool rinsed the water

14. Diagram of harrow machine :-
A –feeding conveyor
D –bowl with perforated
Flase bottom
E –outlet
F –out put conveyor
G –squeeze roller

15. TECHNOLOGY OF
BLEACHING -2
POWER POINT PRESENTATION

16. DegumDming of raw silk :
• Removal of natural gum from raw silk is
done in 3stages.

17. o To bath 12.15% soap and 7% soda ash is used at about
o 50 degree celcious
oIn order avoid in entanglement entire natural is wrapped in gunny bag and
steel in soap solution
oSecond soap bath is used with lesser quantity of soap and soda
oThe final soap bath same quantities of soap and soda is taken as in second
bath
oIn this way silk gum known as sericius is completely removed and degummed

18. BOILED OF LEGOUR
• The legour obtained after degumming silk containing soap and silk
gum is used in all dying operation this boiled of legour being highly
colloidal in nature server as a protective colloid to maintain luster of
fiber and for trevention of Degums due to friction

19. DEGUMMING OF RAW SILK IN BLENDSWITH
WOOL OR ACETATE
• Acetate usually get affected with strong soap solution at high temperature and
hence the following method of degumming raw silk in blend with wool and acetate is
successive
• By Enzymic action
• 20%popping
• 40%thaiosulphate
• 40%hydrosulphate
• Only three gum of above per litre of water used the metrial is worked for two hours
at 65 degree celcious

20. •

21. CONTENT
1. BLEACHING
2. BLEACHING OF NATURAL SILK
3. METHOD OF BLEACHING
4. BLEACHING OF CELLULOSE ACETATE
5. SCOURING OF MAN MADE FIBRE
6. BLEACHING OF MAN MADE FIBRE

22. BLEACHING
BLEACHING IS A CHEMICAL
TREATMENT EMPLOYED FOR
THE REMOVAL OF NATURAL
COLOURING MATTER FROM
THE SUBSTRATE

23. BLEACHING OF NATURAL SILK
Even after degumming by ordinary method, some yellow pigment of
natural silk still remain and this is due to presence of sericine not being
completely removed. When the silk gum is completely removed it
appears perfectly white and only a treatment with suitable optical
whitening agent is sufficient.

24. METHOD OF BLEACHING NATURAL SILK
The bath contains 0.3% H2O2 solution, olive oil soap and sodium
silicate. Temp should be 75C and raised upto 90C. Winch machine
may be used for degumming and bleaching purpose. The degumming
is carried out at 90C and should be complete in between 2-3 hrs. The
goods are washed off and bleached with H2O2 in same machine.
Sodium silicate is added to bleaching bath. The temp during bleaching
shoud be 70C.

25. BLEACHING OF CELLULOSE ACETATE
Cellulose Acetate may be bleached with H2O2. The alkalinity must be adjusted
to 9.5 either by addition of sodium silicate or ammonia. The temp must not be
allowed to exceed 65C. Time period is an hour.

26. SCOURING OF MAN MADE FIBRE
Goods(Polyamide) should be scoured to remove any oil applied picked
up during weaving and knitting. Scouring is affected in a liqour
containing 1-2 g/l of Sodium Tri Phosphate and 1-2 g/l synthetic
detergent at a temp 80-90C. Period of 30-45min is sufficient.

27. BLEACHING OF MAN MADE FIBRE
Bleaching of Polyamide can be done by Paracetic acid. It has all
essential properties of H2O2 but does not need an alkali as an
activator. It bleaches more effectively between ph 6-7 at which
degradation of fibre is less. It effectively removes any discolouration
which arises as a result of heat setting under normal condition

28. • Peracetic Acid-3lb per 100 gallons
• Anhydrous Sodium Pyrophosphate-0.25lb per 100 gallons
• Wetting agent-1lb per 100 gallons
The pH- of liqour is aadjusted by addition of well diluted Sodium Hydroxide
solution. Goods are entered cold and bleaching solution is raised to 80-85C
over a period of 30 min and then retained at this temp for further half an hour.
After bleaching wash the material with cold water

29. SUBMITTED BY
Group- VI
SATYAM
JUGENDRA
ASHISH BANSAL
SACHIN
VIPIN
VINOD KUMAR
SANGAM KUMAR
SACHIN KUMAR

30. TECHNOLOGY OF
BLEACHING -2
POWERPOINT PRESENTATION

31. Topic-
•Fluorescent brightening
agent
•Application of fluorescent
brightening agent
•Uses of fluorescent

32. FLUORESCENT BRIGHTENING AGENT
•Compounds with oxidizing or reducing properties
are classified as bleaching agent because they
decompose the natural colouring.
•Bleaching agent also introduce a complementary
colour.
•The result of this is that distribution of reflected
light is more uniform.
•Optical brightening agent of fluorescent
brightening agent counter the reflection of excello

33. APPLICATION OF FLUORESCENT
BRIGHTNING AGENT
• Optical brightening agent may be applied by either Exhausoion or
padding method. Natural fibre require prior bleaching for an acceptable
white. The man made fibre are usually softning white
• Cellulosic fabric generally required between.0.05 and 0.6 present on the
weight of the goods .from a long liqour by exhaustion methods. The
goods are entered into a cold liiqour, temperature period of 15 minutes
to the optimum for the product which is being used. When required
temperature has been reach a further 30 minutes of running will be
sufficient for complete exhaustion when padding method are used
solution containing between 0.05 to 2 gpl are necessary according to

34. USES OF OPTICAL BRIGHTENING
AGENT
1.Protein fibres
2.Polyamides
3.Polyester
4.Polyacrylonitriles

35. PROTEIN FIBRE
•Tinopal, uvitex etc are D.B.A suggest for wool and
Silk. They are applied from debarred adjusted to PH
between 3and 5 by addition of organic acid. The
Liquor is made up with required D B.A, acitic or
formic acid is added to Bring pH 3 to 5. Goods are
entered and temperature is raised to 40°c during a
period of 15 minutes and maintain for another 20
minutes.

36. POLYIMIDES
• O.B.A suitable for cellulosic can be applied to polyimides
but exhausting is inddequate. These are number of optical
brightening agent which are used for cellulose are applied
to polyamide from a liqour Containing organic acid.
• pH of Liqour should be 3.5 to 4 temperature recommended
iS 40c to 70°v c
• Light fastness is 1 to 2 and washing fastness at 60°c in
0.5% soap solution in 3

37. STER
They have no affinity for water soluble O.B.A but have affinity for
the compounds insoluble in water. Exhaustion is very slow so
career it’s reqminute’m/c is required to raise tempeure Liqour is
made up wiTh
1 to 2% O.B.A. Material to be treated is entered between 40 and
50°c and Run for 15 minutes at this temperature. What is raise to
boil over a period of 30 minutes and boil for further 30 to 60
minutes.

38. POLYACRYLONITRILES
Mainly cationic O.B.A . Are preferred. They are applied from
iiqour Containing
3 to 5 .formic acid to maintain pH 3 to 4 at a temperature
between 95o 100°c.

39. NATURAL BAST FIBERS
1. BAST FIBER ARE PRODUCED FROM RENEWABLE AGRICULTURE CROPS
WITH NO PESTICIDES AND LITTLE ARE NO HERBICIDES.
2. BAST FIBER HAVE BEEN USED FOR THOUSAND OF YEARS BEFORE
PETROCHEMICAL FIBERS WHERE DEVELOPED AND PUSHED THEM ASIDE.
3. BAST FIBER CAN REDUCE COST , REDUCE WEIGHT ,REDUCE
MANUFACTURING TIME AND IMPROVE SAFETY IN AUTOMOBILES. EUROPEAN
AUTOMAKERS HAVE ADOPTED THEM AND ARE EXCEPTED TO USE UP 70000
METRIC TONS OF FIBER BY THE YEAR 2005

40. NATURAL RENEWABLE FIBERS
BAST FIBERS LEAF FIBERS SEED FIBERS FRUIT FIBER
FLAX SISAL COTTON COCONUT
HEMP CURAUA KAPOK
KENAF BANANA
JUTE PINEAPPLE
RAMIE

41. BLEACHING OF JUTE
JUTE IS DIFFICULT TO BLEACH SUITE. IT SURFACE DEGRADATION WHEN
TREATED WITH CHLORINE ESPECIALLY IN ALKALINE. THE BEST VARIATION HAVE
LITTLE COLOR AND CAN BE DYED WITHOUT BLEACHING
JUTE GIVES HARSH FEEL DUE TO LIGNIN. LIGNIN IS REMOVED PARTLY
BY TREATMENT WITH CAUSTIC FOR HALF HOUR WITH 18-20% NAOH FOR
COMPLETE DELIGNIFICATION. SOME CHLORINE CONTAINING AGENT IS
REQUIRED SAME LIKE COTTON

42. DISADVANTAGE
THIS PROCESS CAUSES HIGH STRENGTH LOSS
SCOURING
SCOURING OF MATERIAL IS DONE WITH 3% NAOH AT BOILING TEMP. FOR 1 HRS.
THEN WASH THE MATERIAL WITH COLD WATER AT ROOM TEMP. AND TREAT
WITH ACID TO NEUTRALIZE THE ALKALI

43. BLEACHING OF JUTE IS DONE WITH HYDROGEN PEROXIDE. MATERIAL IS
TREATED WITH 3% HYDROGEN PEROXIDE 3% SODIUM META SILICATE 2% SODA ASH
10%SOAP FOR 1HRS. HYPOCHLORITE IS NOT RECOMMENDED AS AT CONTAIN
CHLORINE WHICH WAY CASES DEGRADATION. HYDROGEN PEROXIDE GIVE HALF
BLEACH TO GET PURE WHITE MATERIAL IS AGAIN TREATED WITH ABOVE RECIPE
ADDING
COLD BLEACH PROCESS
Hydrogen peroxide 6%
Caustic soda 3%
Soda ash 3%
Soap 1%
Temp RoomTemp
ENTER THE MATERIAL IN THIS SOLUTION. PREPARED WITH ABOVE CHEMICALS FOR 24
HRS. WASH WITH HOT WATER AND COLD WATER THIS PROCESS GIVEN FULL
WHITENESS

44. TOPIC
BLEACHING WOOL WITH H2O2
BLEACHING WITH SULPHUR DIOXIDE
BLEACHING WITH SODIUM
DITHIONITE(SODIUM
HYDROSULPHITE)

45. BLEACHING WOOL WITH
H2O2•Bleachin is carried out with 0.3 to 0.6%
peroxide liquour adjusted to the pH
829 with a mild alkali at a temperature
between 50 degree to 55 degree
Celsius A very common practices is to
leave the goods in a standing bath
overnight. Take them out

46. •The traditional method of bleach liqour
for wool age as follow
•Tetra sodium pyrophosphate 2g/l
•E.D.T.A 30%. 1g/l
•H2O2 35%. 13m/l
•Or H2O2 50%. 9ml/l

47. •When bleaching is completed the wool
must be rinsed
•Thoroughly and treated in a liqour
containing 0.5% of
•Acetic acid to neutralise alkali

48. BLEACHING WITH SULPHUR
DIOXIDE
•This is the oldest method Wool is bleached by
stretching
•It over a lattice frame in the cautre of which small
pot of
•Burning sulphur is placed.
•This method gives adequate bleach for lower
quality goods

49. •It is a cheap method and required only simple
equipment
•The equipment consists of chamber fitted with rails
in which wooden poles can rest . Moistured wool
goods are
•Hung over there poles and a cost iron pot containing
sulphur is placed in the chambers.

50. •Sodium sulphite to remove SO2 other wise
SO2 May be oxidised to H2SO4
•And cause holes.
•A extremely clear white can be obtained by
bleaching with H2O2 first and then
•By SO2

51. BLEACHING WITH SODIUM DITHIONITE
(SODIUM HYDROSULPHITE)
• It is a stable white powder with strong reducing properties .
In first stage pass
• SO2 through an aqueous suspension of ZN dust
• When treated with formaldehyde a stable additional
compound is formed.
• When acetic acid is added.it decomposes slowly on
warming with the formation of HYDROSULPHITE acid
• Wool can be bleached with sodium hydrosulphite or its

52. •In practice they do not find much application
because they tend to import harsh handle .
•They are used as stripping agent to remove dyes
when necessary