Pigments For Printing Inks

 

Pigments for Printing Inks By: Adesh Adesh Katariya

 

Pigment Industrially, a pigment Industrially, is any finely divided insoluble black, white or colored solid material, a major function of which is to t o improve the appearance of or give color to the medium in which it is to be used.

 

• Color phenomenaColour  is the electromagnetic radiation in the wavelength range of 400 to 00 nm! • "hen a photon enters a pigmented film following events may occ#r :   $! It may %e a%sor%ed %y a Pigment particle   &! It may %e scattered %y a Pigment particle   '! It may simply pass thro#gh the film

 

 Pigments : How How they appear? • Pigment m#st have light a%sorption and light(scattering  properties! • If a%sorption is very small compared with scattering) the pigment is a white pigment! • *he a%sorption is m#ch higher than scattering over the entire visi%le region) and then the pigment is a %lack  pigment! • In a colored pigment) a%sorption is selective selective!!  A wide variety variety of wavelengths wavelengths (colors) (colors) encounter a pigment. This pigment  absorbs red and green light, but  reflects blue, creating the color blue.

 

Colo#r Inde+ ,eneric -ame C!I! ,eneric -ame descri%es a commercial  prod#ct %y its recognised #sage class) its h#e and a serial n#m%er .which simply reflects the chronological order in which related colorant types have %een registered with the Colo#r Inde+/ ike C!I! 1ed $&&) C!I! Pigment 2ellow $3

 

#ality and performance of Pigments ,overned %y : •Crystal type •Crystal shape .nod#lar) spherical) prismatic) acic#lar or lamellae / •Crystal si5e : *ypical ranges for average diameter of  primary particles are:   Car%on %lack 6 0!0$ to 0!07 8m   *itani#m *i tani#m dio+ide 6 0!&& to 0!&4 8m! organic 6 0!0$ to $!00 8m9 Inorganic 6 0!$0 to !00 8m9 8m9 •Crystal s#rface properties

 

Performance of pigments in Ink •

;ystem Performance Performa nce is governed %y application type) technology in #se #se and interaction with form#lating Ingredients

• Parameter Parameterss which have to %e taken into consideration) as well modified) are physical form) dispersion  property) a%ility  property) a%ility to stand dispersion condition) rheological %ehavior %ehavior)) colo#ristic properties) heat < light fastness properties) storage properties) etc!

 

Pigments are classified as either organic or inorganic. inorganic. • Organic pigments are %ased on car%on chains and car%on rings! • Inorganic pigments) chemical compo#nds not  %ased on car%on) are #s#ally metallic salts  precipitated from sol#tions

 

Inorg Inorganic anic v=s >rg >rganic anic pigments pigments • Inorganic pigments have a m#ch larger average particle si5e than organic pigments! *his is the main reason why most organic pigments are considered transparent and most inorganic pigments opa?#e! • "ith their larger s#rface area) organic pigments give m#ch higher color strength! @owever) for similar reasons) their dispersi%ility is #s#ally poorer !  • As a res#lt of their chemical composition) inorganic  pigments are sta%le in the presence of organic organic solvents  6 #nlike many many of the simpler simpler organic organic pigments) pigments) which can dissolve 6 and have high resistance to pigment  %leeding and migration! • "ith a few e+ceptions) inorganic pigments have higher heat sta%ility than organic pigments! fastness and weathera%ility vary more@owever) widely! light

 

Cont! Particulars

Inorganic Pigments

Organic Pigments

;o#rce

inerals

Chemically refined oil

Color 

>ften d#ll

Bright

yeing = Coloring ;trength >pacity

ow >pa?#e

@igh *ransparent

ight fastness

ery good

ary from poor to good

;ol#%ility

Insol#%le in solvents

@ave have little degree of sol#%ility

egree of safety

ay %e #nsafe

Ds#ally safe

Chemical ;ta%ility

>ften sensitive

Ds#ally good

Cost

oderate

ostly too e+pensive

 

>rganic Pigments • Azo Pigments Pigment class containing the a5o gro#p .(-E-(/ in common! *he synthesis of a5o  pigments is economically economically attractive! • Poly !yclic Pigments : Pigments with condensed aromatic or heterocyclic ring systems are known as  polycyclic pigments! *heir chief characteristics are good light and weather(fastness and good solvent resistance! *hey are typically costlier than a5o  pigments!!  pigments

 

"ey features and characteristics of Organic Pigments • ery good sta%ility to solvents) light) heat) and weathering • ,ood tinctorial strength • Cost effectiveness • Consistency and #ni?#e shades • Completely non(to+ic • ery %right) p#re) rich colors • >rg >rganic anic pigments shows good color strength

 

o o

A5o ono(a5o 2ellow and Pigments >range pigments Disazo

o o o

o o o

Naphthol Naphthol AS  Azo lakes Benzimidazolone Disazo condensation Metal complex

 

Polycyclic pigments • Phthalocyanine • #inacridone •• • • • • •

Perylene and perinone *hioindigo Anthra?#inone io+a5ine Isoindolinone and isoindolin iketo(pyrrolo(pyrrole iketo(pyrrolo(pyrr ole .PP/ *riarylcar%oni#m

• #inophthalone #inophthalone  

 

onoa5o 2ellow and >range Pigments • onoa5o yellow pigments that are o%tained %y a co#pling a dia5oni#m salt with acetoacetic acrylides) as co#pling components) cover the spectral range %etween greenish and medi#m yellow9 while co#pling with $( acrypyra5olone( affords reddish yellow to orange shades! • All mem%ers of this family share good light fastness) com%ined with poor solvent and migration resistance! • P2$) P2') P# $%, P# $& etc!

 

ia5o Pigments • aFor prod#cts :P2$&) P2$') P2$) P27' • ia5o Pigments divided into two gro#ps • *he first and most important gro#p incl#des compo#nds whose synthesis involves the co#pling of di(salt andwith tetra( s#%stit#ted diaminodiphenyls as dia5oni#m acetoacetic acetoace tic arylides .diarylide yellows/ or pyra5olones pyr a5olones .disa5o Pyra5olones/ as co#pling components! • *he second gro#p) %isacetoacetic arylide pigments) are o%tained %y dia5oti5ation of aromatic amines) followed %y co#pling on to %iacetoace %iacetoacetic tic arylides! *he color potential of disa5o pigments covers the color range from very greenish yellow to reddish yellow and orange and red!

 

•

G(-aphthol Pigments G(-aphthol Pigments provide colors in the range from orange to medi#m red!

• *he typical co#pling reaction with G(naphthol) as a co#pling component) yields s#ch wellknown  pigments as *o *ol#idine 1ed and initroaniline >range! • Availa%le h#es are tol#idine red .P1') P14H) P1') P137/ and a few orange .dinitraline orange P>) P>$) P>43/

 

Pigments .-aphthol .-aphthol  -aphthol A; Pigments 1eds/

• *hese pigments are o%tained %y s#%stit#ting co#pling aryl dia5oni#m salt with arylides of &(hydro+y('(naphthoic acid .&( hydro+y('(naphthoic hydro+y ('(naphthoic acid anilide E -aphthol A;/! A;/! •  *hey provide a %road range of colo#rs from yellowish and medi#m red to %orde#+) carmine) %rown) and violet9 their solvent fastness and migration resistance are only marginal! • *he color range is concentrated in the long wavelength end of the spectr#m) incl#ding warm orange .P>&4) P>'7/) scarlet .P1$77) P1&3$/) many reds .P'() P1') P1) P1) P')) P1H) P1$) P1&&) P'**() P1$0) etc!/) carmines .P1&') P1$43) the many pigments listed #nder P'*$+/) maroon violet .P$') P&) P44/) and %rown .PBr$/!

 

A5o Pigment akes • *hese pigments are formed %y precipitating a mona5o compo#nd) which contains s#lfo and=or car%o+y gro#ps! • *he co#pling component in the reaction may vary: %(naphthoic acid lakes are derived from &(naphthol) B>-A pigments pigments lakes #se &( hydro+y('(naphthoic acid .Beta(>+y( -aphthoic Acid/9 Acid/9 and -aphthol A; pigment lakes contains anilides of &(hydro+y( '(naphthoic acid) as a co#pling component!

• akes may also %e prepared from naphthalene ake 'ed %(naphthol ! is one oflakes! s#lfonic acids!significant the ! commercially lakes

 

 

Ben5imida5olone pigments

• Benzimidazolone pigments feature the benzimidazolone structure, structure, introduced as part of the coupling components. •  These pigment obtained o btained by coupling onto 5-acetoacetyl 5-ace toacetyl aminobenzimidazolone cover the spectrum from greenish yellow to orange; while 5-!-hydro"y-#-naphthoylamino$benzimidazolone as a coupling components a%ords products that range from medium red to carmine, maroon, bordeau", and brown shades. shades. •  Broad range of hues, from yellow &'(!),   PY151, &'(5+,&'(5, &'(), &'((, &'(+$, through orange &/#0, &/#, &/0), &/0!, &/!$ and red &1((, &1(5, &1(0, &1(5, &1!)$ to a maroon of fair lightfastness &2#!$.

 

isa5o Condensation  *hese

pigments can formally %e viewed as res#lting from the condensation of two car%o+ylic monoa5o components with one aromatic diamine!

 *he

res#lting high molec#lar weight pigments show good heat sta%ility and light fastness!

  *heir

main markets are in the plastic field and in spin dyeing!  *he spectral range of disa5o condensation pigments e+tends from greenish yellow to orange and %l#ish red or %rown!  Availa%le

h#es range from yellow yel low .P2H') P2H) P#*(), P#*--/) orange .P>'$/) red .P1$44) P1$33/ and %rown .PBr&')PBr4&/!

 

etal Comple+ Pigments

• All com%ine a symmetrical pair of car%on .organic/ compo#nds with a metal atom .#s#ally nickel or copper/! •

Incl#ded in this gro#p are the a5o(methine metal comple+es! Colors range from green .P,7/ to green gold .P,$0)P2$$) P2$&H/) yellow .P#*+, P2$') P2$) P2$H/) orange .P>H) P>3/) and red .P1&) P1&$/!

• *hose species that provide the re?#ired light fastness and weather resistance are #sed in a#tomotive finishes and other ind#strial coatings! • *hey are nonto+ic %#t may .depending on the metal atom #sed/ irritate the skin!

 

• Phthalocyanine pigments are derived from the Phthalocyanine pigments  phthalocyanine str#ct#re) a tetraa5a(tetra(%en5o(porphine! • Altho#gh this %asic molec#le can chelate with a large variety of metals #nder vario#s coordination conditions) today only the copper .II/ comple+es are of practical importance as pigments! • Commercial varieties incl#de the reddish %l#e alpha form) as sta%ili5ed and non(sta%ili5ed pigments9 the greenish %l#e %eta modification! Bl#ish to yellowish shades of green pigments may %e  prod#ced %y introd#ction of chlorine or %romine atoms into the  phthalocyanine molec#le!

 

Cont!!

• An important pigment from the family of Copper phthalocyanine is the C!I! Pigment Bl#e $:'! • *he prod#ction steps of which is given here!

 

/uinacridone pigments • @ighly recommended for high light fast and @igh resistance application! • As on now maFor cons#mption in ink Fet inks as well as high ?#ality process magenta shades • #e to %etter transparency) the com%ination with  pearlescent and metallic metallic pigments creates creates o#tstanding eff ects that can easily %e applied for coatings andeffects inks! • *he availa%le h#es range from golden yellow .P>4H/) thro#gh reddish orange .P>47/) middle red .P1&0H/) coral .P1&0/) red .P$H/) rose .P$H and P4&/) .P'*(( maroon .P1&03/) and a dark reddishmagenta violet . P0*1 /! ) P1&0&/)

 

Isoindolinone and Isoindoline Pigments • Altho#gh of comparatively good light and weather fastness) solvent and migration resistance) only a few mem%ers of the isoindolinone and isoindoline families are commercially availa%le as pigments! • Chemically classified as heterocyclic pigments) they are prefera%ly s#pplied for high grade inks! • Colors range from yellow .P2$0H) P2$$ P2$$0) 0) P#*&1) P2$') P2$7/ to orange .P>3$) P>33) P>3H/ and red .P'(-+/!

 

Perylene Pigments • Perylene pigments are prepared %y the condensation of  perylenetetracar%o+ylic monoanhydride monoimides with primary amines! • Perylene pigments are very sta%le thermally together with photo sta%ility ! •

Availa%le colors are limited to moderately sat#rated scarlets .P1$&')P1$4H) Availa%le P1$H0/) reds .P1$7/) dark maroons .P1$H0) P1$H) P1&&4) P&H/) and a very dark green . P2k&*/!

 

3io4azine • *he pigment is o%tained %y dissolving the dye in a very the hot precipitate acid) then washing and salt grinding that res#lts! • *he pigment e+ists in two crystal modifications) a red and a  %l#e shade) whose h#e can %e modified %y different different methods of man#fact#re or grinding: %oth have the same color inde+ name) are poorly disting#ished %y man#fact#rers) and are apparently conf#sed in the lightfastness testing literat#re

• Pigment 0iolet (& and '

 

Anthra?#inone • A small gro#p of a%o#t $0 pigments) most of them with a long history as te+tile vat dyes! •  *hey made d#ll) weak pigments #ntil methods of  p#rification) caref#l precipitation precipitation and grinding were were discovered that retained most of the dyes color •

 %rilliance! *he gro#p incl#des anthrapyrimidine yellow .P2$07/) anthra?#inoid red 5P'*$$/ and my favorite) indanthrone %l#e .PB30/!

•

,ood 1e(sol#%ility in ;olvent %ased %ased Inks: Dse to improve resol#%ility 

 

iketo(pyrrolo(pyrrole .PP/ • A small %#t very important gro#p of new synthetic organic pigments) discovered in the early $H70s and systematically developed into pigments with very good lightfastness! • A%o#t si+ are c#rrently offered) in the shades orange .P>$) P>'/) scarlet .P1&/) red .P'(%/ and carmine .P1&34) P1&4/! •  All the pyrroles are nonto+ic) e+tremely lightfast) semitransparent to semi(opa?#e) and staining!

 

6riarylcarbonium!

• *wo gro#ps of triphenylmethane pigments) o%tained %y laking %asic dyes! • Color range is green .P,$) P,&) P,4) P,4/) %l#e .PB$) PB&) PBH) PB$0) PB$4) PB$7) PB$H) PB3) PB3$) PB3&/) red .P')*) P1$3H/ or violet .P$) P&) P0&, P0($, P'H/! • *heir lightfastness ranges from poor to worthless and no paint containing these pigments or any #nlaked %asic dye sho#ld %e #sed in professional ?#ality artworks!

 

#inophthalone • /uinophthalone pigments prepared with #sing of  phthalic anhydride and &(methyl?#inoline derivatives as starting materials and BJ' as catalyst #nder solvent(free and refl#+ conditions! • *hese pigments pigments are opa?#e in nat#re) fastness to weathering ) ow migration nat#re) satisfactory @1) gloss sta%ility and flow properties9 the o#tstanding color strength makes it the preferred prod#ct for economic form#lations! • *hese are non(*o+ic to animals %y oral) so widely #sed for fish foods! • P2 $'7) P# *&1, P2 $7

 

Inorganic pigments • *i *itani#m tani#m dio+ide white • Car%on %lack  • Iron o+ide • Dltramarine %l#e • Chrome %ased pigments • ff ffect ect Pigments . Pearl) etallic etc!/

 

Car%on %lack • Car%on %lack .PBK(/ is the name of a common  %lack pigment) traditionally prod#ced from ccharring harring organic materials s#ch as wood or %one! •  It appears %lack %eca#se it reflects very little light in the visi%le part of the spectr#m) s pectr#m) with an al%edo near 5ero!

• resistant @igh strength) good go od colo#r) light light < weather

 

•

*itani#m tani#m dio+ide(*i>& 5P7-8 *i 6itanium dio4ide Is the nat#rally occ#rring o+ide of titani#m!  

• *he three common phases of titani#m dio+ide are r#tile) anatase and  %rookite! 1#tile is the most sta%le form of titani#m titani#m dio+ide! Anatase and %rookite are sta%le at normal temperat#res %#t slowly convert to r#tile #pon heating to temp! a%ove 0 and 0 LC) respectively! • Appro+imately 4!3 million tons of pigmentary *i>& are #sed ann#ally worldwide! • @igh strength) high h igh opacity) cheap) good D resistance! • aFor pro%lem: forms radicals that degrade the %inder!

 

9anufacturing of 6i 6itanium tanium 3io4ide • Chloride Process

• ;#lfate Process

 

 

Iron o+ide Pigments

• Ds#ally mined altho#gh can %e synthesi5ed •  -at#ral iron o+ides are derived from hematite) which is a red iron o+ide mineral9 limonites) which vary from yellow %rown) s#ch as ochers) siennas) and #m%ers9 and magnetite) which isto%lack iron o+ide! • Also can %e prod#ced synthetically %y thermal decomposition of iron salts or iron compo#nds) precipitation of iron salts #s#ally accompanied  %y o+idation) and red#ction red #ction of organic compo#nds %y iron • ight and weather resistant) #nreactive • India is world leader in prod#ction of Iron >+ide Pigments • Cannot prod#ce clean shades

 

Chrome Pigments • *hese pigments are chromi#m %ased pigments! • Ink companies are avoiding to #se these  pigments d#e to presence of @eavy etals! • ight) weather) alkali and acid resistant9 thermally sta%le • ain prod#cts are ;tronti#m Chromate) emon Chrome) iddle Chrome) Primrose Chrome) ;carlet Chrome and Minc Chromate Chr omate !

 

 

Dltramarine Bl#e

• Dltramarine Bl#e is ;ynthetic Inorganic! It is a %l#e pigment of sodi#m al#minosilicate containing s#lph#r s# lph#r!! •  It is prepared %y heating kaolin) sodi#m car%onate) s#lph#r and other ine+pensive ingredients together! • It is heat and alkali resistant!

 

ffect ect Pigments Pigments ff  *he theory of optics as a wave  and  com%ination of Chemistry

 

 

Pearl l#ster pigments

• 1eg#lar reflection takes place on highly refractive parallel pigment platelets • *i *itani#m tani#m dio+ide on mica

 

pigments • 1eg#lar etal reflectioneffect takes place  

•o *ypes: o o

Al#mini#m Pigments. eafing=-on(eafing/ ac##m etalli5ed Pigments ,old%ron5e Pigments

 

Interference pigments • *he optical effect of colored l#ster pigments is ca#sed mainly d#e to interference of light! • Iron o+ide on mica

 

D Jl#orescent Pigments • D Jl#orescence Pigment a%sor%s Pigment radiation of a certain wavelength) or gro#p of wavelengths) and re( emits photons of a different wavelength wavelength ) witho#t a delay   • ost of these pigments are e+cited %y short wavelength D light .aro#nd &4 nm/! • ;ilver(doped 5inc s#lfide  

Dnder -ormal ight

Dnder D ight

 

Phosphorescent pigments • *hese pigment has a%ility to a%sor% light and then emitted lightafter of longer wavelength within severalthe ho#rs e+citation! • "hen am%ient darkness occ#rs) it %ecomes highly visi%le! • +amples: copper(doped 5inc s#lfide • Commonly called Nglow(in(the(darkO • Dsed in ;creen Inks for ;ign Boards

 

I' :luorescent 5Anti;ffset and ;olvent Based inks! • ;pecial near I1 lasers or s are needed for detection! • Dnder isi%le light) they appear white and in -ear I1 1egion) they appear colo#red! • I1 fl#orescent pigments do not ;tokes law) they are e+cited %y I1 energy) and either emit in the visi%le region or in the I1 region %#t at a shorter wavelength!  

3ame &igmented 4oating n 2isible 1egion

n ) nm 1 1egion

6hite

'ellow

   

 

>ptically >ptic ally aria%l ria%lee Pigment Pigmentss

• PP show angle(dependent color and lightness effects which are %ased on reflection) interference and a%sorption phenomena of visi%le light in  pigmentary m#ltilayer systems!

 

6hermochromic Pigments • *hermochromic Pigments change change their color %eca#se of the Change of *emperat#re • Change in the molec#lar str#ct#re as per temperat#re! • Also press#re dependent pigments are #sing • Dses in >ffset and ;creen Inks 3ame coating have

7t (5 84

7t #) 84

6hite

/range

 

!!

  *hank 2o#