Textile printing , methods of printing textiles

The document deliberates on the printing methods of textile materials.

1. TEXTILE PRINTING
Gezu k
WolkiteUniversity
2012

2. Textileprintingisrelatedtodyeingbut,whereas
indyeingprocesswholefabricisuniformly
coveredwithonecolor,inprintingoneormore
colorsareappliedtoitincertainpartsonly,and
insharplydefinedpatterns.
ATYPEOFCOLOURATION FORIMPARTINGCOLORIN
SPECIFICAREAONASUBSTRATEBASEDONPATTERN
ORDESIGNREQUIREMENT.
Textile Printing Defined

3. DIFFERENCES BETWEEN
DYEING AND PRINTING

5. PRINTING
Printinginvolveslocalizedcoloration
Thisisachievedbyapplyingthickenedpastescontainingdyes
orpigmentsontofabricsurfaceaccordingtoagivencolordesign
Thepastemustcolorallthevisiblefibersontheprintedsurface
Soitmustpenetratesomewhatintotheyarnstructure
Ifthepasteistoothinitwillspread,givingpoorprintdefinition
andpenetratetoofarintotheyarnsdecreasingthecoloryield

6. PRINTING PROCESS
PREPARATION OF PRINT PASTE
APPLICATION OR PRINTING
FIXATION

7. DYE OR PIGMENT
THICKENER
BINDER
AUXILIARIES
PRINT PASTE INGREDIENTS

8. Imparttherequiredcolorofdesignasperrequirement
Dyesarechosenwithrespecttotheiraffinity
Example:Reactivedyesforcotton,aciddyesforwool,dispersedyesforpolyesterandsoon
Pigmentsareappliedforallkindsoffibertextiles
DYE OR PIGMENT

9. Tolocalizetheprintingpasteonthedesiredareaofthefabric.
Enables the print paste to stay in place once it is
deposited onto the fabric
Clear cut design and proper outline definition of
print
Naturaland syntheticthickeners are available
Based mainly on polysaccharidesand polyacrylic
acids
THICKENER
Optimum Viscosity

10. Desirablepropertiesofthickenersusedinpigmentprinting:
lowsolidcontent
clearandcolorless
don’tdecreasethefastnessandhandoftextileprints
goodlevelingpowerwithoutspreadingsideways.

11. Pigmentsarefixedbybindershencebinders
providedurabilityofthepigmentonthefabric.
Apigmentbinderistheresinthatformsathree-
dimensionalfilmonthesurfaceofthefiber.
Thisfilmcontainsthedispersionoftextilepigment
andwillacttoadherethepigmenttothesurfaceof
thesubstrate.
Thepermanenceofthisfilmisdependentonthe
polymertypeandtheapplicationconditions.
BINDER

12. Crosslinking agents to improve fastness
Softeners to improve handle of pigment printed
fabric
Defoamers to prevent foam generation
Humectants to increase water content of the
paste
catalyst and so on
AUXILIARIES

13. DIFFERENT TECHNIQUES CAN BE USED TO
TRANSFERTHEPASTETOTEXTILESUBSTRATE.
THETRANSFER CAN BEBYMEANS OFBLOCKS,
SCREENS, ROLLERS :REPRODUCTION OFIMAGE.
THERE ISPOSSIBILITY OFDIGITIZING DESIGN AND
TRANSFER IMAGEWITHOUT REPRODUCTION .
APPLICATION OF PRINT PASTE

14. DRYING AND CURING
(STEAMING)
The main purpose of drying is to control
migration
Curing/steaming for fixation of
pigment/dye
Cylinder dryers and stenterscan be
used
Curing temperatures depend on the
180
o
C for pigment, 205
o
C for
dispersed dye

15. Inthecaseofdyeprints,theprintedfabric
isthoroughlywashedthendriedafter
fixation.
Necessarytoremovethickener,alkali,
otheringredientsofprintpastelefton
fabricafterfixation.
Couldinterferewithsubsequentfinishing
processes.
AFTERWASHING

16. Reactivedyesforcottonfibershasgiventhepossibilityof
usingonlyonetypeofdyeandsimpleapplicationconditions,
inplaceofthecomplexpermutationsnecessary
Reactivedyesproducebrilliantshadesofverygood
fastnessandlevelingpropertiesoncellulosicfibers.
Nexttopigmentprintingthemost
importantprintingmethodisprintingwith
reactivedyes.
REACTIVE DYE
PRINTING

17. Selectionofthickenersisveryimportantforreactivedye
printings;andtheselectionofproperreactivedyesalsoplays
amajorrole.
Normallylowreactivedyesarepreferredforprintingoncotton.
Becausethestabilityofthelowreactivedyesishighin
printingpaste.
Furthermoreforobtaininggoodeffectproperpretreatmentof
fabricbeforeprintingisveryimportant.

18. Requirements of an ideal thickener for reactive
printing
Good compatibility and no affinity or reactivity with
dye
Good flow property
Good swelling and moisture absorption capacity
during steaming for dye fixation
Quickdryingtopreventbleeding&goodwater
solubilityforeasyremoval
Easy availability, cheapness & good storage

19. Conventional reactive printing thickener
Theusualpolysaccharidethickenerssuchasstarchand
gumsusedinprintingarenotsuitableforprintingwith
reactivedyes
Asallthesecontainprimaryhydroxylgroupsintheir
molecularstructureandreactwithreactivedyes.
Sodiumalginateiswidelyusedforreactivedyeprinting.It
isananionicpolymer,hasonlytwofreeOH
groups.

20. Polysaccharide illustration
Thereactionbetweenalginateanddyeislimitedbyanionrepulsion
ofalginate'scarboxylgroupsanddye'ssulfonicacidgroups.

21. Moderate to low reactivity dyes such as MCT
and VS
Reactive dyes in printing
Dyeshavinglesssubstantivitytowardscellulosearepreferredfor
printing.
Becauseofgreatereaseof“washingoff”andavoidanceof
stainingofadjacentwhiteareas.
Printingpastesmadefromlessreactivedyeshavebetterstorage
stabilityandthisisofconsiderableimportance.
Thereactiveprintpastenormallycontainsreactivedye,
sodiumbicarbonate/carbonate,urea,sodiumalginateand
water.
DCTisnotrecommended

22. PIGMENT PRINTING
DIFFERENCE BETWEEN DYE AND PIGMENT
PIGMENT
NO AFFINITY TO FIBRE
INSOLUBLE IN WATER
NEED BINDER FOR FIXATION ONTO FIBRE
DYE
AFFININTY TO FIBRE
WATER SOLUBLE OR CAN BE MADE WATER SOLUBLE
HELD ON FIBRE DYE-FIBRE INTERACTIVE FORCES
MOST WIDELY
USED

23. MECHANISM OF BINDING
SEQUENCE:
PRINT > DRY > CURE (DRY HEAT)
DURINGCURINGBINDERPOLYMERIZESANDFORMSA
STRONGFILM.
BINDERFILMEMBEDESPIGMENTCOLOURANDALSO
STRONGLYADHERESTOTHEFIBRE.
BINDERISAPRE-POLYMERAVAILABLEINTHE
FORMOFAQUESOUS EMULSION
CROSSLINKING

25. CHOICE OF THICKENER
DYEPRINTINGTHICKENERSARENOTSUITABLE.
INTERACTWITHBINDER,REDUCE INTERATIONWITH
FIBRE.
AFFECTINGTHEFASTNESSPROPERTIES
SUITABLE THICKENERS
EMULSION THICKENER
SYNTHETIC THICKENER
DEVELOPMENT OF VISCOSITY
HMW COPOLYMERS OF ACRYLIC
ACID
OIL + WATER EMULSIONS

26. ADVANTAGES OF PIGMENT PRINTING
PRACTICALLY ALLTYPESOFFIBRESANDBLENDS
CANBEPRINTED
PIGMENTCOLOURS CANBEREADILYMIXEDWITH
EACHOTHERTOGETQUICKSHADEMATCHING
NOAFTERTREATMENT SUCHASWASHING&SOAPING
REQUIRED
DISADVANTAGES
HARSH FABRIC FEEL DUE TO BINDER FILM
LOW RUBBING FASTNESS

27. FIBERCHARACTERISTICS
YARNTYPES
FABRICCONSTRUCTION
CONSIDERATIONS ON PRINTING PROCESS

28. Styles of printing
There are two basic styles of printing
Direct printing andIndirect printing
DIRECT PRINTING
Thedyeorthepigmentisprintedonthefabricinthepasteform
andanydesiredpatternmaybeproduced
Designsprinteddirectlyusingpigmentsordyesonwhiteor
coloredbackground
Isthemostimportantprintingstyleandthemostpopularas
comparedtoindirectstyle

29. Indirect printing
IP is classified into two categories
Discharge printing
Indischargestyle,thefabricisdyedtotherequiredground
color.Next,thefabricisprintedwithachemicalthat
selectivelydestroysthedye.
Thisallowsprintingofwhitedesignsonagroundcolorofanydepth
withapatterndefinitionthatismuchhigherthanwouldbepossibleby
directcolorprinting.
Ifthepastecontainsdyesresistanttothedischargingagent,these
dyes,calledilluminatingcolors,willcolortheprintedareas.

31. Resististhetermthatdescribespreventionofdyeing
processbyapplicationofaphysicalorchemical
substancetofabrictopreventadye’saccesstofabric.
Resistagentscanbewaxes,thickeners,surfactants,
organicacids,oxidizingagents,orreducingagents.
Indischargestyle,thefabricisdyedtotherequired
ground color.Next,thefabricisprintedwitha
chemicalthatselectivelydestroysthedye.
Resist printing

32. BATIK
TIE-DIE

33. Inbatikeffectthefabriciscoatedwithwax
andthendyedwithsuitabledyes
dependingonthefiber.
Intie-dieeffectfirstthefabricistiedin
certainportionstolowerthepenetrationof
dyeintothefiberandthendyeingis
carriedoutconventionally.

34. Methods of Printing
Non contact printing
Contact printing

35. STENCIL PRINTING
BLOCK OR SURFACE PRINTING
ENGRAVED ROLLER PRINTING
SCREEN PRINTING
TRANSFER AND DIGITAL PRINTING
TECHNIQUES OR METHODOF PRINTING
Refers to the technical means by which pastes are put onto design areas

36. Stencil printing
Stencilprintingistheprocessofcutouttherequireddesigns
ontheplasticpapers
Thesurfaceofthepapersshouldbesmooth
Colorantsaresmallermolecularweight(noneedofwashing)
Pastesareforcedoutthroughcuttingoutshapesfrom
papersontofabricunderneath
Theideaofscreenprintingisoriginatedfromstencil
printing

37. BLOCK PRINTING
Itistheoldestandsimplestwayofprinting
Inthismethodawoodenblockwitharaisedpatternonthe
surfacewasdippedintotheprintingcolorantandthenpressed
facedownontofabric.
Thedesiredpatternwasobtainedbyrepeatingtheprocess
usingdifferentcolors.
Generallythewoodenblockiscarvedoutofhand
Printingisdonemanually

39. Screenismadeofwovenfabricsfirmlyattachedtoa
suitableframe
Mostlyofnylon/silk/polyester
Thescreenistheimagecarriermadefromaporousmesh
stretchedtightlyoverametalorwoodenframe.
Reproducepatternsasperdesignrequirement.
SCREEN PRINTING
SCREEN, INK, SQUEEGEE

40. 40
(Majorstepinscreenprinting)
(1)theselectionofthefabricandtheprinteddesign
(2)thechoiceofthesizeandarrangementofdesign’s
repeatrectangle
(3)thenecessarycolorseparationofthedesign
Colorseparationinvolvesreproduction
ofthepatternforeachcoloronseparate
clearfilmswithopaquetracer.
Screen production

41. Single color Multi color

44. 44
Thescreeniscoatedwithaphoto-sensitiveemulsion.
Atypicalpolymerispolyvinylalcohol,its
crosslinkingsensitizedbyammoniumdichromate.
Thecoatedscreenisdried
Exposedbeneathdiapositiveforthegivencolor
All operations take place in a dark-room!!
Screen Preparation Steps
Lacquer

45. Theinkedzones,correspondingtoparticular
colorpattern,donottransmitultravioletlightused
forexposure.
Thelayerofpolymeronthescreenbeneaththe
patternisthusnotexposedanddoesnotcrosslink.
Theresthardens(becomeinsoluble)
Thenon-exposedpolymerremainssolubleandcanbe
washedout,leavingthescreenopeninthoseareas.
Anysmallholesinhardenedareasonscreenarepaintedover.

46. MIXINGPHOTO-EMULSION
COATING
DRYING
PREPARINGPOSITIVE
EXPOSING
WASHINGANDDRYING

47. 4747
Flatscreenprintingcanbecarriedoutbyhandandautomaticallyby
usingdifferentmachines.
Rotaryscreenprintingiscarriedoutbyfullycontinuousmachines.
TYPES OF SCREEN PRINTING
FLAT SCREEN PRINTING
Inflatscreenprinting,ascreen
onwhichprintpastehasbeen
appliedisloweredontoasection
offabric.Asqueegeethen
movesacrossthescreen,forcing
theprintpastethroughthe
screenandintothefabric.
ROTARY SCREEN PRINTING
Thetubularscreensrotateatthe
samevelocityasthefabric,the
printpasteisdistributedinsidea
tubularscreen,whichisforced
intothefabricasitispressed
betweenthescreenandaprinting
blanket(acontinuousrubber
belt).

49. •Printingiscarriedoutonaflat,solidtablecoveredwith
alayerofresilientfeltandawashableblanket.
•Heatfordryingtheprintedfabricmaybeprovidedeither
undertheblanketorbyhotairfansabovethetable.
•Fabricmovementorshrinkagemustbeavoidedinorder
tomaintainregistrationofthepattern.
HAND SCREEN PRINTING

50. Theprocessconsistsofforcingprintpastethroughthe
openareasofthescreenwithasyntheticrubber
squeegee(rubberbladecontainedinwooden/metalsupport)
Therubberbladeisdrawnsteadilyacrossthescreenata
constantanglespeedandpressure.
Thescreeniswashedimmediatelyafteruse.Ifthisisnot
done,pastedriesonscreenandclogsupdesign.

51. S
C
R
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P
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MANUAL

55. SEMI-AUTOMATIC FLAT SCREEN PRINTING
55
Themanualprocesshasbeensemi-automatedby
mountingthescreeninacarriage.
Insemi-automatedscreenprinting,amechanicallydriven
squeegeetransfersthecolor.
Longtables,typically20–60mlong,areused,andsome
provisionisusuallymadefordryingtheprintedfabric.
Verypopularwherethescaleofproductionisnot
large,orwherecapitalinvestmentislimited.

56. FULLY AUTOMATIC FLAT -SCREEN PRINTING
•Toincreasethespeedofflat-screenprinting,itwas
necessarytodeviseamethodofprintingallthe
colorssimultaneously.
•Allthescreensforthedesign(onescreenfor
eachcolor)arepositionedaccuratelyalongtop
ofalongendlessbelt(blanket)ontopofwhich
isthefabrictobeprinted.
•Thefabricisgummedtotheblanketattheentryendandmovesalongwiththeblanketin
anintermittentfashion,onerepeatdistanceatatime.

57. •Allcolorsindesignareprintedsimultaneouslywhile
thefabricisstationary;thenthescreensareliftedand
thefabricandblanketmoveon.
•Whenthefabricapproachestheturningpointofthe
blanket,itispulledoffandpassesintoadryer.
•Thesoiledblanketiswashedanddriedduringitsreturn
passageontheunderside.

58. PRODUCTIVITY

59. Correctfabricplacementisvitalforaccurate
registrationofthedifferentcoloredpatterns.
Aslightpatternoverlappreventsawhitegap
betweentwoprintedcolors.

60. 60
Themainfaultinscreenprintingispoorpatternregistration
Inaccurate screen placement
Inaccurate fabric movement
Fabric slippage on the blanket (poor adhesion)
Distortion of screen mesh by drag of squeegee
PROBLEMS IN FLAT SCREEN PRINTING
SLOW PRINTING PROCESS [5 -10m/min]

61. 61
Number of squeegee passes
LOW PRODUCTION RATE
Morethanonepassisusedtoachieveuniformityandadequatepenetration,
especiallyinblotchareas,forthickfabricsorirregularsurface
Squeegeetakeslongertomovealongthescreen
wheretherepeatdistancesarelarge
Efficiency of the dryer
Ifthedryerisshort,oriftemperatureindryeristoolow,printingspeedwill
havetobereducedinordertoensuretheprintedfabricisadequatelydried.

62. ROTARY SCREEN PRINTING
Theprocessinvolvesinitiallyfeedingfabriconto
therubberblanket.Asthefabrictravelsunderthe
rotaryscreens,thescreensturnwiththefabric.
Printpasteiscontinuouslyfedtotheinteriorof
thescreenthroughacolorpipe.

63. •Asthescreenrotates,squeegeedevicepushesprint
pastethroughthedesignareasofthescreenonto
thefabric.
•Asinflat-bedscreenprinting,onlyonecolorcan
beprintedbyeachscreen.Afterpaste
application,theprocessisthesameasflat
screenprinting.

64. 64
Byconvertingthescreen-printingprocessfromsemi-continuous
tocontinuous,higherproductionspeedsareobtained.
Typicalspeedsarefrom45-100mpmforrotaryscreenprinting
dependingupondesigncomplexityandfabricconstruction.
Continuouspatternssuchaslinearstripesarepossible.
Rotaryscreenmachinesaremorecompactthanflatscreen
machinesforthesamenumberofcolorsinthepattern(lessfloor
space).

65. 65
Gluestreaks–fromtherubberblanket
Colorout–fromalackofprintpaste
Creasedfabric
Pinholesinanyscreen
Damagetothescreenleadingtomisprints
Lintonthefabriccausespick-off
Withprintdesigns,colorapplicationmustbecorrectthefirsttime,
becauseprintingdefectscannotberepaired.
General screen printing defects

66. 66
Longprocesssetuptimeforcolorandpattern
change
Screenproductionisslowandexpensive
Screensrequireconsiderablestoragespace
Limitations Specific to Rotary Screen
Printing

67. ROLLER PRINTING
Engravedrollerprintingisamoderncontinuousprinting.
Thedesignisengravedonthesurfaceofametalroller,to
whichdyeisapplied,andtheexcessisscrapedofftheroller's
surface,leavingdyeintheengravedsections.
Whenitrollsacrossthefabric,thedyeontherollertransfers
tothefabric.

68. TRANSFER PRINTING
Heattransferprintingisatechniquewherepaperisprinted,followedby
thetransferofthedesignfromthepaperontothetextilefabric.
Commercialprocessinvolvesprintingreleasepaperwithpigments.
Thedesignonpaperisplacedontothefabric,heatedso
thatthepigmentbindersoftens,releasesfromthepaper,
andadherestothefabric.
Heattransferprintingiscleanandenvironment
friendly
Theonlyby-productisthepapercarrier.
Transferringanimagetofabricfromapapercarrier.Whenheat
andpressureareappliedtothispapertheinksaretransferred.

69. DIGITAL PRINTING
It is the more advanced type of printing.
This includes :-
 Jet spray printing
 Electrostatic printing
 Photo printing
 Differential printing

70. Rotary Screen Printing60%
Automatic Flat Bed 18%
Other methods 22%
WORLD PRODUCTION SHARE