Textiles Section 2

Color solutes or substancesmove from solution or dispersion to fiber or other objects

Dyeing

Colorants need binders to be “glued” into textiles

pigment coloration

Patterned coloration

Printing

Fibers come with colors via ____________

Genetic Modificaitons

the attraction between a dye and a fiber under specified dyeing conditions

affinity / substantivity

Dyes— Good fastness (affinity) without ______

binders

Dye provide ___________ due to no binder

good hand

Classification of colorants

Method of application, chemical constitution

Method of application colorants

Direct, Reactive, azoic, vat, sulfur, acid, premetalized, mordant (chrome), basic (cationic), disperse

azoic dye is _________ but ______

cheap, toxic

Chemical constitution

Azo (manazo, diazo, triazo), carbonyl (anthraquinone and indigo derivatives, cyanine, di / tirphenylmethane, phtholocyanine

Dyes containing anionic groups

acid, direct, mordant, reactive

dyes containing cationic groups

basic / cationic

Disperse dye is water_________

insoluble

Dyes requireing chemical treatment beofre applicaiton

vat, azoic, sulfur

two important dye structures

azo, anthraquinone

Special colorant charges

disperse, solvent, pigments, natural

Long and linear, used to dye cellulose, many NaO groups, water soluble, active charge in water, connected by azo

Direct dye

Used for cellulosics, Anthraquinone , water soluble, negative charge in water, excellent colorfastness, only dye that will chemically react with fiber molecules to form strong covalent bonds, connected by azo

reactive dye

Azoic Dye

intermediate is toxic

vat dye

Doesn’t dissolve in water, good colorfastness, carry negative charges in dyeing through process called vatting / redox, non linear / planar structure, forms crystals inside fiber, high saturation, only dye class that can handle chlorine bleach, connected by azo

light colors, naturally colored cotton, reactive dyes,

safer, more colorfast

Cheapest dye (especially for dark shades / black), not bright, long linear molecular structure (polymer), connected by sulfur

sulfur dye

Longer polymer structure =

darker color

sulfur dye is used to create______

black

Uses acid during dyeing (dye does not include acid, must have positive charge, water soluble, anthraquinone, cobalt complex,

Acid dye

acid is used to generate a _________ in acid dyeing

positive charge

acid dye

metals

metal in acid dying provides

unique color, excellent color fastness

chromium ions can be added to form bonds with nitrogen,

mordant / chrome dye

Provides most saturated colors, only dye class that carries a positive charge, least colorfastness to light,

Basic / cationic dye

only dye class that carries a positive charge, making it unstable

basic

fiber that can handle sunlight the best

acrylic

acrylic is typically dyes with cationic / basic dyes making it

fade in light

Only dye class that is water insoluble during dying, no charge, forms dye dispersion not a solution

Disperse dye

Hydrophobic materials =

hydrophobic dyes

Cellulosic fiber charge in water

-

Cellulosic dye selection

direct, vat, reactive, sulfur,

Cellulosic dye charge in water

+

Protein fiber charge in water

+

Protein Dye selection

—

basic dyes are very unstable on_________

cellulose

Polyester fiber charge in water

none

_____ picks up lots of dye

nylon

acetate/tricacetate fiber charge in water

none

Polyester dye selection

Disperse

Acetate/triacetate dye selection

Disperse

_________ can be used for any fiber

pigments

Polyester dye charge in water

none

acetate/triacetate dye charge in water

none

increases the dye/fiber interaction

agitation

agitation

speeds up dying, improves levelness

most dyes have poor ___________ properties once on the fiber

diffusion / migration

diffusion / migration

easy in, easy out

dyeing rate / speed of dyeing

levelness, dyeing time, termperature profile, dyeing compatibility, shade matching

easy to dye= ______ colorfastness (assumed same dye class and fiber)

worse

hard to dye= ________ colorfastness (assumed same dye class and fiber)

better

speed of dye moving onto fabric (must be controlled)

levellness

determines how well colormatching is done

dye compatibility

increased temp = ________ dying

faster

increased temp = higher equilibrium ads.

endothermic reaction

increased temp = lower equilibrium ads.

exothermic

under acid conditions, dyes are typically most __________ than under alkali or neutral conditions

stable

effect of pH on dyeing

dyeing sites on fiber, charge on dye, stability of dye + fiber + bonds

______ always decreases ionic interactions between dye and fiber

salt

adding salt will decrease or increase

dye uptake

if ionic attraction, dye uptake ______ with salt

decreases

if ionic repulsion, dye uptake ________ with salt

increases

up to _______ of salt is added?

10%

almost _____ ratio of salt is added to fiber

1:1

salt can be added to improve_______

levelness

Dyeing quality evaluates

dye pickup, color matching, eveness, colorfastness

dye quality dye pickup is determined by

% exhaustion

% dye exhaustion is calculated from the concentration difference

before and after dying

color matching and evenness are determined with

visuals, colorimetric measurement, cross sectional microscope evaluation

yarn has a ring of color

ring dyeing

most important in colorfastness

washing, crocking, light

evaluation of the shade of the dyed material after different treatment (most have 5 classes: 5 being best, 1 being worst)

colorfastness

colorfastness evaluation

washing, bleaching, heating, acid, alkali, crocking, perspiration, light, grey + chromatic transference scale

Dyeing recipe Liquior ratio (dye liquid to fabric)

40:1

Dyeing recipe 1% dye (owf) =

1 g dye / 100 g fabric

owf

based on the weight of fiber or fabric

owb

based on weight of bath

nonionic watting agent =

0.005 g wetter / g dye liquid