 to detect very slight hues, black ink may still have a certain amount of hue and appear neutral.
One method for attempting to achieve a neutral black color is an inefficient process known as under printing. When black ink with a known hue is used for printing, other colors that have been selected to neutralize the colored hue in the black ink may be first printed on a print medium. The black ink is then printed over these colors. For example, when black ink with a blue hue is used, magenta or yellow inks, are applied to the print medium in a first pass of the ink jet nozzle, and then the black ink applied over the top of the magenta or yellow inks in a second pass of the inkjet nozzle.
The neutrality of the black ink affects the quality of gray scale. Particularly, when black ink with a significant hue is used, the visibility of the hue color becomes increasingly apparent with each lighter shade of black in the transition from black to white. Therefore, complex images requiring a large gray scale will be of poor quality when produced by black ink with a significant hue and appear as brown, tan, or another intermediate color. Further, the sharpness and detail of the image may be compromised.
Accordingly, investigations continue into developing ink formulations which have improved properties and which do not improve one property at the expense of the others. Thus, the challenge remains to further improve the light fastness, optical density, color neutrality, gray scale quality, and pen performance of black ink jet inks.
It has been recognized that inkjet ink, which has an improved light fastness and optical density is highly desirable. It has further been recognized that inkjet ink, which has an improved neutral color, or hue, and an improved gray scale is highly desirable. It has been also recognized that inkjet ink, which possesses the above-recited improvements while maintaining or improving printability performance is very desirable.
Accordingly, the present invention provides a black ink composition for inkjet printing which includes a mixture of pacified Reactive Black (pRB) 31 and Direct Black (DB) 168 dyes, in an inkjet ink vehicle. Additionally, the present invention provides a black ink composition for inkjet printing which consists essentially of a mixture of pRB 31 and DB 168 dyes in an inkjet ink vehicle. In one aspect, the dyes may be present in a salt form. In another aspect, the salt form of the dyes may be a salt form selected from the group consisting of: sodium salts, lithium
to detect very slight hues, black ink may still get a sealed amount of hue and appear achromatic. 
 One method acting for attempting to achieve a neutral black semblance is an inefficient process know as under printing. When black ink with a know hue is used for printing, other colors that have been selected to neutralize the biased hue in the black ink may be first printed on a photographic print medium. The black ink is then printed over these colors. For model, when black ink with a blue hue is used, magenta or yellow inks, are apply to the print medium in a first pass of the ink jet beak, and then the bootleg ink enforce over the top of the magenta or yellow inks in a second pass of the inkjet nozzle. 
 The neutrality of the black ink affects the timbre of grey scale. peculiarly, when bootleg ink with a significant hue is used, the visibility of the hue color becomes increasingly apparent with each unaccented shade of black in the transition from black to egg white. Therefore, complex images requiring a large gray scale will be of inadequate quality when produced by black ink with a significant hue and look as brown, tan, or another intermediate coloring material. farther, the sharpness and detail of the image may be compromised. 
 Accordingly, investigations continue into develop ink conceptualization which have improved properties and which do not better one property at the expense of the others. therefore, the challenge remains to further improve the light fastness, ocular density, semblance neutrality, grey scale quality, and pen performance of black ink fountain inks. 
 It has been recognized that inkjet ink, which has an improved light fastness and optical density is highly desirable. It has further been recognized that inkjet ink, which have an improved neutral color, or hue, and an improved grey scale is highly desirable. It has been also greet that inkjet ink, which possesses the above - recited improvements while maintaining or improving printability performance is very desirable. 
 Accordingly, the present invention provides a black ink constitution for inkjet impression which includes a mixture of pacified Reactive Black (pRB) 31 and Direct Black (DB) 168 dyes, in an inkjet ink vehicle. Additionally, the present invention provides a black ink composition for inkjet printing which dwell essentially of a mixture of pRB 31 and DB 168 dyes in an inkjet ink fomite. In one aspect, the dye may be present in a salt form. In another aspect, the salt form of the dyes may be a salt form choose from the group consisting of: sodium salts, lithium
 to detect very slight hues, black ink may still heve a csrtain aoount of hue and appear neutcal.
Obe meukod for attempting tu achieve a neutrql boqck color ma an incyficiskt prmress known as ukder printitg. When black hny cith a known hue is used for printind, other cllors that havg beem selsbttd to neutralize the colored hue jn the ulack ink may br first printed on a print medlum. The black ink ls then pribted iver these culors. For txcmple, when glack ink with a blue hue is usdd, mayenta or yeoliw ltks, are appoied no the print medium it a firxt pass of the inn jwt nozzle, and then thx black ink applied jver the do' of the magenta or ywloow itks hn a wecund pess of thf iikjet nozzls.
The neutraoity of the black imk qffects the qhality os gray scale. Particularly, when black inn wjth a significant hue iw used, the visibility of the hte color becomes increasingly apparent with each nightxr shcee of vlwck in the transition from black to white. Thewsfprv, complex images vequiring a large brwy fcale will be of poor suality when produfed by flack ink with a sognificant hue and appear aw brown, tan, je another intermednate color. Fbrther, the xharpness and detail of the image may he comprojksed.
Accordingly, knvvstications continue into devejoping inj foxmulatiovs wnich hwve improvfd properties and which fo noj imprmve one prlperty at the expense of the otixrs. Thus, the vhdllvnge remanns to further imprjve the light yastness, optizal densitj, color nxutrality, grwy scale qualhjy, and pen pecformance of vlacj ink jdg inks.
It has bren recogunzed that inkjet ink, which mas av improved light fawtness and optival degspty if highly desisabld. Ig has wurther beek rdcogmized that inkjet inn, whjch has an improvec keutral cilor, or rue, and an imlroved gray scale ls hijhly dxsirabke. Yt has been also recognized thzt inkjet inh, which possqssew the above-rzcited improvements while maintaining or improving printabulity performance ix very desireble.
Acsordingly, the present inventiin provides a blagk ink composition for inkjed prijting which includes a mixture of pacified Reactive Black (pRB) 31 and Direct Black (DB) 168 dyes, in an onkjen iuk rehicle. Addmtmonally, the presemt invention provides a black iik composidijn for inkjet printing which cunsists essenjially of a mixture of pRB 31 and DB 168 dyes in an inkjet ink vehicle. In one aspect, the dyes kay be peesenf in a salv form. In another aslect, tke salr form if tme dyes may be a xapt form sflecued yrom the group consisting of: sodiym salrs, lithium
to detect very slight hues, black ink have certain amount hue and appear to a neutral black is an inefficient known as under printing. When black with a known hue is used for printing, other colors that have been to neutralize the colored hue in the black ink may be first printed a medium. black is then printed over these colors. For example, when black ink with a blue hue is magenta or yellow inks, are applied to the medium in a first of the ink jet nozzle, then black ink over top the magenta or inks in a second pass of the inkjet nozzle. The neutrality of the black ink affects the of gray when black with significant is used, the the hue color becomes increasingly apparent shade of black in the transition from black white. Therefore, images requiring a large gray scale be of poor quality when produced by black with a significant hue and appear as brown, tan, or another intermediate color. Further, the detail of the image be compromised. Accordingly, continue developing formulations have improved and which do not improve one property at the expense of others. Thus, the challenge remains to further improve the light density, neutrality, gray scale and pen performance of ink inks. It has been inkjet which light and density is highly desirable. has further been recognized that ink, which has an and an improved gray scale is highly desirable. has been also recognized that inkjet ink, possesses the above-recited improvements while maintaining or improving printability performance is very Accordingly, the provides a black ink composition for inkjet printing includes a mixture of Reactive Black (pRB) 31 and Direct Black (DB) 168 in inkjet ink Additionally, the present provides a black composition for inkjet consists essentially a of DB 168 dyes in an inkjet vehicle. one aspect, the dyes may present salt form. In another aspect, the salt form of the dyes may be a salt from the group consisting sodium lithium
 to detect very slight hues, blaCk ink may stIll haVe a CerTaIn amOunt Of hue and appear NEutrAl.
One method for attemptiNg to aChIEve a NEuTral bLack colOR iS AN inEfFiCieNt PRoCess kNowN as undeR printing. WHen BlAck ink with a kNOwN hue is used For Printing, otheR coLors thAt HavE Been sEleCted tO neutrALize thE colored hUe IN the blACk ink maY BE fIrst Printed on a print meDIuM. the black ink is tHen priNtED oVER thEse Colors. For eXaMple, wHEn black INk WITH a bLUe hue is used, maGenta or yellOW inKs, are aPpLieD To the pRint mEdIUm iN a first pass Of thE ink jet noZzle, anD Then the BLack ink ApplieD ovEr tHe toP Of ThE maGeNTa oR YeLloW InkS in a secoNd PaSs of tHe inKJET NozzLe.
THe neUtralIty of the black Ink AffeCTs tHe quaLity oF graY sCale. PArticuLarly, WhEn black ink with a SignIficant huE is UsEd, tHe VisibILity of The Hue Color beComes inCReaSiNGLY aPparent with each ligHtER ShAde of blaCk in thE TrAnSItion froM bLacK to wHITe. TheRefoRE, cOmplex imAges reQUiRiNg a largE gRay scaLe WilL be Of pooR QualIty wheN produceD by blACk ink with a signIFicant hue and aPPeAR As BRown, Tan, Or another inTermEDiatE colOR. FUrtHEr, the SharpNeSS aND detail of the image maY bE comprOmiseD.
Accordingly, iNvestigatiONS Continue Into DEvELoping ink formuLatioNs which havE Improved PropeRties and Which do noT IMprove onE prOpeRty At tHE ExPense of the othERS. ThuS, tHe challEngE remainS to FurTheR imPrOve the ligHt fastneSs, OpTiCaL deNsity, COlor neutRaLitY, gRay Scale QUality, And peN perFoRmANce Of black INk JET inkS.
IT hAs beEn rEcOgnizEd thAT inKjet ink, Which has aN imPRoveD lIgHt fastnEss and optical DeNsity is higHlY deSirablE. iT has furtHer been recognized that inKJet ink, wHicH has aN impRoved neutRal Color, oR huE, And an iMproveD gray ScAle IS HighlY DEsIraBlE. It has been ALSo rEcognIzEd thAt inkjeT ink, which possesses THe aBove-recited imProVemeNTS wHilE MaINtaInINg oR IMproving printabIlity perfoRmANcE is very desIRabLe.
accordiNgly, the PreseNT inventIon providEs a black iNk CompOSItiOn for inkjeT printinG which incLUdes a MIxTure oF paCified reActIve BlAck (pRB) 31 ANd DIrect black (Db) 168 dYes, in aN inkjEt Ink vehicLe. Additionally, the presenT invenTion pRovIdes a blacK inK ComPosition fOr inKjet printiNg wHicH consIstS EssenTialLY oF a mIXture Of pRb 31 And DB 168 dyes IN aN inKJEt Ink vehicle. IN ONE asPect, tHe dYEs may bE preSent in a salt form. In ANother aspect, thE salT FOrm Of tHE dyeS mAy be a salt form sEleCtED From the gRoUp consistinG of: sodiuM sALts, liThium
 to detect very slight hue s, black i nk ma y s til lhave  a c ertain amounto f hu e and appear neutral.One m et h od f o rattem pting t o  a c h iev eaneu tr a lblack  co lor isan ineffic ien tprocess know n  a s under pr int ing. When bl ack  ink w it h a known  hu e isused f o r prin ting, oth er colors that ha v e  b eenselected to neutr a li z e the coloredhue in  t h eb l ack  in k may be f ir st pr i nted on ap r i ntm edium. The bl ack ink ist hen  print ed  ov e r thes e col or s . F or example,  whe n black i nk wit h  a blue hue isused,mag ent a or ye ll owin k s,a re  ap p lie d to the  p ri nt me dium i n a fi rst  pas s ofthe ink jet n ozz le,a ndthenthe b lack  i nk ap pliedoverth e top of the ma gent a or yell owin ksin  a se c ond pa ssofthe ink jet noz z le. 
T h e ne utrality of the bl ac k in k affect s theq ua li t y of gra ysca le.P a rticu larl y ,when bla ck ink wi th  a sign if icanthu e i s u sed,t he v isibil ity of t he hu e  color becomes increasinglya pp a r en t  wit h e ach lighter  sha d e of  bla c kint he tr ansit io n  f r om black to white.Th erefor e, co mplex imagesrequiringa l arge gra y sc a le will be of poo r qua lity whenp roducedby bl ack inkwith a si g n ificanthue  an d a ppe a r  a s brown, tan, o r an ot her int erm ediatecol or.  Fu rth er , the sha rpness a nd  d et ai l o f the image ma ybeco mpr omise d .
Acco rding ly,in ve s tig ationsc on t i nuein to  dev elo pi ng in k fo r mul ationswhich hav e i m prov ed  p roperti es and whichdo  not impro ve  on e prop e r ty at th e expense of the others .  Thus,the  chal leng e remains  to  furth eri mprove  the l ightfa stn e s s, op t i ca l d en sity, colo r neu trali ty , gr ay scal e quality, and pen per formance of b lac k in k je t i n ks . 
It  h a s b e e n recognized th at inkjetin k ,which hasa n i mp roved l ight fa stnes s  and op tical den sity is h ig hlyd e sir able. It h as furth er been r e cogni z ed  that  in kjet i nk , w hichhas an imp roved  neutr al  color , orhu e, and a n improved gray scale i s high ly de sir able. Ithas bee n also re cogn ized thatink jet  ink,  wh i ch po sses s es  th e  abov e-re c ited impr o ve men t s  w hile mainta i n i ngor im pro v ing pr inta bility performanc e  is very desir able . Acc ord i ngly ,the present in ven ti o n  provide sa black ink  composi ti o n for  inkje t prin ting wh i c hi nclude s amix ture of p aci fi e d React iv eB lack ( pRB)  3 1 andDirect Blac k (DB) 168 dyes, i n ani n kjeti nkvehic le . Addit i onal ly, the pr esent inven tion p rovi des a  blackin k comp osi ti on for ink j et printi ng wh ich con si stsess ential ly o f a mix ture  o f p RB 31 and D B1 68  d y esin a n ink je t in k vehicle .  In oneasp e ct, the  d yes m ay bep re s e nt in a sa ltform. I n anothera spec t ,t he sa lt for m of t he dyes may  b e a sal t f o r m selecte d from th e  gr ou p co nsisting  o f: s od ium  s alts, lithium
 to_detect very_slight hues, black ink_may still_have_a certain_amount_of hue and_appear neutral.
One method_for attempting to achieve_a neutral black_color_is an inefficient process known as under printing. When black ink with a known_hue_is used_for_printing,_other colors that have been_selected to neutralize the colored_hue in_the black ink may be first printed on_a_print medium. The_black ink is then printed over these colors. For_example, when black ink with a_blue hue is_used,_magenta_or yellow inks, are_applied to the print medium in_a first pass of the ink_jet nozzle, and then the black ink_applied over the top of the_magenta or yellow inks in_a second_pass of the inkjet nozzle.
The_neutrality of the_black ink_affects the quality_of gray scale. Particularly, when black_ink with a_significant hue is used, the visibility_of_the hue color_becomes_increasingly_apparent with_each lighter shade_of_black in_the_transition from black to white. Therefore,_complex_images requiring a large gray scale will_be of poor quality_when_produced by black ink_with a significant hue and_appear as brown, tan, or another_intermediate color._Further, the_sharpness and detail of the image may be compromised.
Accordingly, investigations continue_into developing ink formulations which have_improved properties and which_do not_improve_one property at_the_expense of_the others. Thus, the challenge remains to_further improve_the light fastness, optical density, color_neutrality, gray scale quality,_and_pen performance of black ink jet_inks.
It has been recognized that inkjet_ink, which has an improved_light_fastness_and optical density is highly_desirable. It has further been recognized_that inkjet ink,_which has an improved neutral color, or_hue,_and an improved gray scale is_highly_desirable. It has been also recognized_that_inkjet_ink, which possesses the above-recited_improvements while maintaining or improving printability_performance is very desirable.
Accordingly, the present invention provides a_black ink composition_for inkjet printing which includes_a_mixture_of pacified Reactive Black (pRB) 31 and Direct Black (DB)_168 dyes,_in an inkjet_ink vehicle. Additionally, the present invention provides a black ink_composition for inkjet printing which consists essentially_of a mixture of pRB 31 and DB 168 dyes in_an inkjet ink vehicle. In one aspect, the_dyes may be present in a salt_form. In another aspect,_the_salt form of the dyes may be_a_salt_form_selected from the_group consisting of:_sodium salts, lithium