Textiles section 2

Greige fabric

fabric off the loom

wet processing step

preparation, coloration, finishing

Preperation

make the substrate as pure as possible and ready it for futher processing/ coloration

substrate

fiber polymers

preparation is also called

pretreatment

finishing is also called

post treatment

greige fabric has

cotton seed fragments

preparation removes impurities from

plant, process, mistake

_________ of whiteness is more important than degree

consistency

__________ is not always a good quality inicator

whiteness

Types of preparation

heat setting, singeing, desizing, scouring, bleaching, mercerizing

singeing

to remove hair— not for filiments

sizing

coating to make yarns stronger during weaving process

desizing

only used for material which was sized

sizing is typically only for

warp yarns

slashing

sizing on warp yarns

sizing prevents

dye penetration

sizing is not needed for

knitted yarns

scouring

chemicals to remove impurities like seed fragments (natural) or oil (manufactured)

mercerization is most often done to ____

cotton

mercerization

lets fibers have more consistent dyeability

white spots on cotton caused by no

mercerizing

mercerization is only for

natural fibers

heat setting is only for

thermoplastics

thermoplastics

some of regenerated fibers are thermoplastic + all synthetics

improves dimensional stabiity to thermoplatic fabrics

heat setting

heat setting temperature

above glass transition below melting point

heat setting

causes molecules in fibers to realign, making fabric smooth, decreasing shrinkage

polymer in heat setting moves at

high temperature

polymer moves at high temp, reorganize molecular forces, relieves stress, alter morphology, molecular interactions established needs higher temp to be broken

heat setting mechanism

Tg< _____ < Tm

heat setting temp

heat setting temp is typically

370-400 < 1 min

moisture can be used to improve heat setting results of

nylon

polyester = only ____ heat setting

dry

benefits of heat setting

dimensional stability, wrinkle removal, DP performance, pilling, smoothness, strength

negative effects of heat setting

can affect dye uptake, can set contaminants on fabric, can harshen fabric hand, can cause strength loss

singeing

to obtain smooth fabric appearance

fabric passes rapidly over a row of gas burners which remove projecting hairs

singeing

fabrics are singed in full width, under tension, to keep surface _____

flat

singeing variables

speed, distance between flame and fabric, flame intensity

benefits of singeing

cleaner/smoother surface, less pilling, keeps loose fibers from clogging machinery

potential negatives of singeing

streaks from uneven singeing, fusing of fibers or yarns

impurity removal

desizing, scouring, bleaching

knit fabrics are not

desized

100% synthetic or dark, dull fabrics are not

bleached

Process conditions, water heat setting

lubricant and swelling agent, usually steam, enhance molecular movement, lower temperatur or shorter time, common for nylon

common for nylon, wet heat setting, better dye uniformity, lower temp

superba

common for nylon

bleaching damaages fabric and can reduce phyical properties by

20%

bleaching can lower cotton DP from 2000 to

1000

nylon heat setting dry

sussen

impurities are

natural (associated with fiber), added for a reason, or added by mistake

water heat setting is not used for

polyester or polyester blends

added for reasons

fiber lubricants (manufactured fibers), tints, yarn lubricants (knitting), sizing compound (weaving), chalk marker

composition of raw cotton can have up to ___ % minerals

10

Added by mistake

processing lubricants (ex. grease, oil), rust, metals

natural impurities on cotton= ___%

4-12

added impurities on cotton warps= ___%

10-15

added impurities on cotton fabrics= ___%

6-10

amount removed from cotton and poly cotton blends

20-25%

amount removed from synthetic and synthetic blends

5-12%

three parameters for chemical reactions

time, temp, chemical concentration

removes sizing materials from woven fabric

desizing

protective coating added to warp yarns before weaving de decrease warp breakage during weaving process

size

increases weaving efficiency and fabric quality

sizing

common sizes

starch, PVA, polyester, Acrylic, (polyacrylater)

10-13% PVA / starch (acrylic binder)

cotton, poly cotton

8-10% PVA / starch or acrylic

poly rayon

weaker material needs _____ size

more

6-8% PVA (polyester binder)

polyester spun

7-9% PVA

rayon

4-5% acrylic or polyester

polyester

acyrlic is alo called

polyacrylate

lubricants/waxes, softeners, antistats, defoamers, humectants, penetrants, preservatives, emulsifiers, tints, binders, release agents

size additives

most ____ are not water soluble so we must make it soluble

starch

starch is the _______ size to remove

hardest

easy penetration of chemicals for later processes, reduction of chemicals, uneven distribution of residual size, avoid size getting in alkaline processes

reasons for desizing

enzymes, oxidizing agents, acids, caustic soda

additives for starch removal

temp of enzymes for starch removal

warm

temp of oxidizing agents for starch removal

warm-hot

temp of acids for starch removal

cold-warm

temp of caustic soda for starch removal

hot

PVA, Polyacrylates, dispersible polyesters

water soluble / dispersible sizes

temp for water soluble size removal

160-200

surfactant for water soluble size removal

0.1-0.5%

chelating agent for water soluble size removal

0.05-0.1%

Ph adjustment (polyacrylate) for water soluble size removal pH

10.5-11.5

Ph adjustment (polyester) for water soluble size removal pH

<8

Ph adjustment (PVA) for water soluble size removal pH

none

fragments of cotton seeds

motes

weak manufactured fibers

rayon

sizes

starch, pvs, polyactilate, polyester

hardest size to remove

starch

scouring removes impurities _______ fibers

inside

______ swells softends and pops motes

cotton scouring

cotton scouring removes _____ before bleaching

metals

scouring removes grease, oils, and dirt prsent in cotton due to ________

mishandling

scouring removes _______ impurities in cotton like fats, oils, waxes, proteins, pectins, sugars, ash etc

natural

Scouring manufactured fibers usually combines scouring with

desizing

scouring __________ fibers removes size, size additives, fiber finish, dirt, oil, grease

manufactured