lecture-2 Chemicals used in Garments washing .pdf

Various chemical used in washing section of garments.

1. LECTURE-2
Various chemicals and their function used in
garments washing & dyeingplant

2. Whiteningagent
Thechemicalswhichincreasethewhitenessofthegarmentsare
calledwhiteningagents.Thesechemicalsbasicallyusedforwhite
garmentstomakeitmorewhite.Theyalsoreferredtoasoptical
brighteners,opticalbrighteningagents(OBA),fluorescent
brighteningagents(FBA)orfluorescentwhiteningagents
(FWA).e.g-diazoles,triazoles,stilbenes.
Function:Whiteningagentsabsorblightintheultravioletand
violetregionofthespectrumandre-emitlightintheblue
(visible)regionasaresultmaterialslooklessyellowandmore
white.
Enduses:Detergentwhitener,fiberwhitening,textilewhitening
etc.

3. Wetting agent/Penetratingagent
Generallyinterfacialtensionbetweenthetextilefiberandthe
liquorishigh,andhencewettingofthefibersurfacedoesnot
takeplacequickly.Thisisparticularlytrueinthecaseofgrey
cottonfabricandhydrophobicfibers.Waterhasanuncommonly
highsurfacetensionof72dynes/cmbecauseofitsstructure.Itis
possibletobringdownthesurfacetensionofwaterfrom72
dynes/cmto28dynes/cmbydissolvingsoapinwater.Oneofthe
mainfunctionofthesurfactantsistoreducethesurfacetension
andtherebybringaboutwettingofthesurface.

4. Wetting agent/Penetratingagent
Awettingagentorpenetratingagentisakindofsurfactantsbythe
usethatreducesthesurfacetensionofaliquid.Thesurfacetension
ofaliquidisthetendencyofthemoleculesofaliquidtoheld
together.
Whenthewettingagentisapplied,itcausestodistortthestructure
ofwateranddecreasethefreeenergysystemorcreatingparticles
calledmicelles(clusters)whichreducesthesurfacetensionand
allowthepenetrationofthesolidbytheliquid.

5. Fixingagent
Somedyes,mostlyanionicinnature,arenotveryfasttowashing
whenappliedoncotton.Thedyedclothmaybeafter-treatedwith
acationicdye-fixingagenttoimprovethefastnessbythe
formationofacomplexinsidethetextilematerial.Forinstance-
albafixeco,condensateofformaldehydeanddicyandiamideetc.
Afterfixing,thecolorfastnessofwash,colorfastnessoflight
andcrockingwillimprove.

6. Detergents
Detergentsaresurfactantsbytheusewhicharesimilartosoapbutare
moresolubleinhardwater.Theyhelptoremovesoilsfromsolid
surfaces.Detergentsmustabsorbontothesoil’ssurfacetoaidinquick
release.Detergentsmustalsokeepsthesoilsuspendedtoprevent
redeposition.Theyarealsousedtoincreasetheabsorbencyofmaterial
tobedyed.
AccordingtoIonicnature,theyarefourclassesi.e.-
I.Anionic: That develop a negative charge on the water solubilizing
group.
II.Cationic:Thatdevelopapositivechargeonthewatersolubilizing
end.
III.Non-ionic: That develop no ionic charge or remainuncharged.
IV.AmphotericorZwitterionic:Thathavebothapositiveand
negative charge on the molecule.

7. Softeningagents/Softeners
Thechemicalswhichareusedtosoftenthegarmentsarecalled
softeningagent.Thisagentiswidelyusedinwashingsector
becausehandfeelisagreatfactorofgarments.Softenerhas
manytypesbutmostlyusedcationicandnonionicsoftener.
Cationicsoftenershavestrongaffinityforcellulosicmaterials.
Forcolorgarmentsweusedcationicsoftenerandforwhite
garmentsweusednonionicsoftener.
Softenersworkbycoatingthesurfaceoftheclothfiberswitha
thinlayerofchemicals;thesechemicalshavelubricant
propertiesandareelectricallyconductive,thusmakingthefibers
feelsmootherandpreventingbuildupofstaticelectricity.

8. Silicon
Siliconisusedforfinalfinishingofthegarments.Itgivesexcellent
smoothness,goodhandfeelandnicedurabilitytothegarments.Itis
ametallicsubstancebuthashighlubricantpropertiesthat’swhyit
isusedasaslipperingsubstance.
Benefitsofusingsiliconsoftener:
Theabilitytocompletelywetawidevarietyofsubstrates-from
fabric toleather.
Do not interfere with the bulk properties of thesubstrate.
Spread ability andlubricity.
Self-levellingcapabilities.
Typicalapplications:
Textile softeners including hydrophilicsofteners
Thread or fiberlubricants

9. Sequestering/ Chelatingagents
Theseagentsremovemetallicionfromasolutionbyentrapping
themandformingacomplexionthatdoesnothavethechemical
reactionsoftheionthatisremoved.Waterhardnessandheavy
metalse.g.copper,ironetcareremovedduringprocessing.i.e.
EDTA,EDTMPetc.
TheseagentsbindpolyvalentcationssuchasCa,Mgexistin
water,thuspreventingtheprecipitationofsoaps.
They are used inPre-treatment and dyeingstage.

10. Enzyme
Enzymeareproteins,composedofhundredofaminoacidwhich
areproducedbylivingorganism.Theyareresponsiblefor
numberofreactionsandbiologicalactivities.Itisalsobio-
catalystandorganiccompoundofhigheratomicweight.They
areveryspecificabouttheirwork.Theirreactionsarecontrolled
bythetemperature,density,pHandtime.
Characteristics:
I.Livingorganism
II.Complexprotein
III.Very definite foraction
IV.Sensitive fortemperature
V.Interaction power isless
VI.It is soluble in water but insoluble in alcohol andacid

11. Types of enzyme used in garments washing
anddyeing
Mainly two typesof enzyme used in our country,namely-
1.Acid enzyme (liquidform)
2.Neutralenzyme
a)Powderform
b)Liquid form (SLenzyme)
Commonapplicationofenzymeinvariousstagesoftextile
processingare-
Desizing:amylase,lipase
Scouring:pectinase andcellulase
Bleaching:oxidoreductase,xylanase
Dyeing:oxidoreductase
Finishing: cellulase,lipase andoxidoreductase

12. Acidenzyme
Color is slightlybrown
pH range is4.5-5.5.
Temperature range 40-50C
Time require 25 minutes to 50minutes.
Enzyme action occurs within shorttime.
Staining/Bleeding occurs more ingarments.

13. Powderform
Slightly white powderform
pH range is6-7.
Temperature40-60C.
Time required 40-70minutes.
Enzyme action occursslowly.
Less staining andbleeding.
In dark shade enzymeaffect
comesgood.
Liquid form(SL
Enzyme)
Liquidform
pH range is6-7.
Temperature range 40-60C.
Time required 45-80minutes.
Enzyme affects comeslowly.
In dark shade enzymeaffect
comesgood.
Neutralenzyme

14. How do enzymeswork?
Enzymesworklikeall
catalystsbyinteracting
withthesubstratesor
reactantstogeneratean
intermediateenzyme-
substratecomplexthat
lowerstheactivation
energyforthereaction.
Thisresultsinadramatic
increaseinthereaction
ratecomparedtothe
uncatalyzedreaction.

15. Bleachingagent
Themainobjectofbleachingistheremovaland/ordestructionof
naturalandadventitiouscoloringmatterswiththeproductionofpure
whitematerials.Bleachisachemicalthatcanremoveorlighten
color,usuallyviaoxidation.Bleachingagentisthatagentwhichis
usedtoreducecolorfromgarments.Ithasvarioususeatother
industriesalso.Bleachingagentusuallytwotypes:
a)Oxidativeagents:O2,O3,H2O2etc.
b)Reductivebleachingagents:CO2,SO2,H2Setc.
HydrogenPeroxide:Itisthesimplestperoxideandastrong
oxidizer.Hydrogenperoxideisaclearliquid,slightlymoreviscous
thanwater.Indilutesolution,itappearscolorless.Duetoits
oxidizingproperties,hydrogenperoxideisoftenusedasableachor
cleaningagent.Duringprocessing,itproducesperhydroxylionby
ionizationwhichisresponsibleforbleachingaction.

16. CausticSoda
(NaOH)
Causticisastrongalkali
substance.Itisalsocleaning
agent.Afterusingthis
pHvaluewill
Itschemical
chemicals
increase.
structureisNaOH.Itis
soluble in water, ethanoland
methanol.
washingit
Ingarments
isusedduring
pigment and burnoutwash.
Soda(Na2CO3)
Itisalsoalkalitypesubstance
toremovecolor.Itisusedfor
desizing,cleaningandscouring
agent.Sodaisusedforgetting
reddishtonewherecausticis
usedforgettingbluishtone.
Sodiumcarbonateorsimply
knownassodaisasodiumsalt
ofcarbonicacidandavailable
insolidform.

17. Acetic Acid(CH3COOH)
Itisanorganiccompoundwiththechemicalformula
CH3COOH.Itisacolorlessliquidthatwhenundilutedisalso
calledglacialaceticacid.TocontrolpHinvariousstageof
washingprocess,weusethis.Itisusedespeciallyinbio-
polishingprocesstomaintaintheacidicmediumofthesolution.
PhosphoricAcid
Phosphoricacidisamineralacidhavingthechemicalformula
H3PO4.Thisacidisespeciallyusedinacidwashwithpotassium
permanganate.Thetermphosphoricacidcanalsorefertoachemicalor
reagentconsistingofphosphoricacids,suchaspyrophosphoricacid.

18. Itisaninorganicchemicalcompoundwiththechemicalformula
KMnO4.Itisastrongoxidizingagent.Itdissolvesinwatertogive
intenselypinkorpurplesolutions.Itisusedtocreatefade/wornlook
intheJeanspantsandotherdenimgarments.e.g.ppspray,pp
sponging,ppspotetc.
Sodium Metabisulphite(Na2S2O5)
Sodiummetabisulphiteorsodiumpyrosulphiteisaninorganic
compoundwithchemicalformulaNa2S2O5.Thissubstanceis
sometimesreferredtoasdisodiummetabisulphite.Itisusedasa
antioxidantandpreservativeagent.Aftersprayingpotassium
permanganate,garmentsareneutralizedwiththischemicalsothat
garmentsbecomefadeandhenceoldlookiscreated.
Potassium Permanganate(KMnO4)

19. Levelling and RetardingAgents
Unevennessinadyedmaterialmaybecausedbyrapiduptakeof
dyesduringdyeingfromaqueoussolution.Thiscanbe
minimizedbyusinglevellingorretardingagents.Theseare
invariablysurfactants-anionic,cationic,nonionic,amphotericor
theirmixtures.
Manybutnotall,levellingagentspromotemigrationofdyein
additiontoretardingthedyeingprocessandsuchagentwillbea
furtheraidtoleveldyeing.Levellingagentsarealsowidelyused
asstrippingagents.

20. RESIN
Resinisusedforthecreationofsemi-permanentcreasesindenimand
othercellulosefabrics.Itisusedalsocottonandpolyesterfabric.
Fabric retainssoft handle afterwashing.
CATANIZER
Catanizerisusedduringpigmentdyeing.Pigmentiscolornot
dyestuff.Pigmenthasnoaffinitytofabric.Whencatanizeris
usedinfabricthenincreasetheaffinitybetweenpigment&
textilematerials.

21. AntistainingAgent
Antistainerisusedtopreventthestainingonweftyarnofthe
denim(whiteyarn),whitepocketsofthegarment,labelsand
increasedthebrightnessoffabrics;itisalsoactsasanti-creasing
agent.
Flax Softener (Cationic, nonionic)
This softener is used to make the garmentsmore soft. It also
provides excellent lubricatingproperties.