CA2076186A1

CA2076186A1 - Fluorescent colorant donor ribbons for thermal transfer imaging

Info

Publication number: CA2076186A1
Application number: CA002076186A
Authority: CA
Inventors: Hsin-Hsin Chou; Christopher E. Kunze
Original assignee: Minnesota Mining and Manufacturing Co
Current assignee: 3M Co
Priority date: 1991-10-25
Filing date: 1992-08-14
Publication date: 1993-04-26
Also published as: EP0539001B1; KR930007680A; EP0539001A1; TW211545B; DE69203073D1; JPH05212973A; DE69203073T2

Abstract

ABSTRACT OF THE DISCLOSURE

A donor ribbon construction suitable for thermal mass transfer imaging comprises a fluorescent colorant donor layer over-coated or alternated with an opaque white donor layer. Alternative constructions are disclosed in which donorlayers containing fluorescent colorant or opaque white background pigments are interspersed alternated, or over-coated on a substrate. A process for transferring a fluorescent colorant image is also disclosed.

47594FOR.APP

Description

lPaten~

~R ~MAL TRANSFER IMA,&l~G
5 3BACK~R011ND OF ~[E ~VENT~
Fluorescqn~ :olorants ha~e been NSed ~ p~l~g both as a detsrre~ to counter~ei~ng and to provide visually attrac~ve i~ges. When colorants ~at are fluorescent in the ~ns;ble ~gion of t~s elec~omagnetic ~c~um a~e used, there is difficul~ in obtaining good, detaile~ fluore~cent color i~es when ~e colo;rant 10 is printed over a color~d baekground. Under these condi~ons, fluorescent colorants tend to appear muddy or washed out.
Japanese Published patent applica~on (Kokai) 1-258,990 disclo~s a ~ermal trans~er donor ribbon coa~ed wi~ h~t mel~ble i~c layer r~gions of 3 primary colors or 4 primary colors plus black and a region containing a fluorescent dye.15 Overprinting of the respective regions with fluorescent dye is disclosed.
Japanese Published patent app~ication ~okai) 63-281,89~ discloses a recording mateAal having a therm~usible ink layer containing a flu~rescent compound and a thermo-~usible in~ layer containing c~lorant and a therrn~fusiUe ink layer containing an e~eende~ with hiding power.
U.S. Patent Nos. 4,627,997; 4,866,C~25; 4,871,714; 4,876,~37; and 4,891,35~ describe therm~l transfer of various fluorescent mate~ials. In prefe~Ted embodiments, the ~luorescent materials are patch coat~d on a donor ribbon along wi~ magenta, cyan and yellow in~ patches. These patents a~e dir~ted at colorlessfluore~cent inks ~at emit in the visible sp~hum upon ~posure to ul~aviolet 25 radiation.
U.S. Patent 3,~47,503 describes a multicolored ~eat transfer sheet in whi~h eolor~d layers are s~u~n~ally coated on a subshate. Th~t patent is directed at multic~lored transfer imaging and requires good por~sity of the uppermost layer tn provide good transfer of dye from lower layers. This is the opposite effect 30 des;red in the present invention.

~ 2 ~ a ~
WIPO publishcd patent application number 10268 (1~89~ discloses a thermal trans.fer ~ibbon haYing a ~ransfer coa~ng including a fluorescent colonng matenal of a reddish~ange hue in a wa~ ma~erial. Ihe ~ans~e~ coating contains 5~90% wa~, incl~ing 20 45~ hydrocarbosl wax, 35-6~% paraffin w~c, 2-30%
5 carnauba wa~ and 2-25% acetate ~polymer; S-20% flu~ressent pigment, and S-20% color to2aing pigment. ~o mention is made of using an opaque white ba~kground layer to improYe image clari~.
IJ.S. Patent No. 4,472,479 de~ribes an impa~t ribbon haYing a l~yer of fluorescent dye over coated with a layer of refl~ve barrier pigment, and arl 10 alternate construction wherein the barrie~ pigment is insluded within the fluoreseent pigment layer. 33ar~ier pigments disclosed in the patent include finely divided reflectivP materials sush as powdered gold and br~nze pigments, and powdered aluminum. Opaque dyes and ~igments such as titanium dio~ide, silica, and alumina are specifically excluded (column 3, ~ines 33~4) as ha~g a tendency 15 to blend with the fluorescent materials on impae~ t~ansfer. lhe use of reflec~ng barner pigments is also des ribed in ~erman Patent 3,042,S26.
U.S. Patent No. 4,816,344 discloses thermal mass transfer of fluorescent pigments, bu~ makes no mention of using an opaque white pigment layer to pr~vide color clarity.
The present inYention overcomes deficiencies of the prior art m providing goQd quali~ fluorescent images ~at are generated by thermal transfer onto colored ba~kgrounds~ The claIity of fluorescent images produced by this method is improved by ~nsfe~ring an opaque white pigment layer simultaneouls or prior to transfer of the fluor~cent pigment layer of ~e donor rib~on.
~ELD OF T~E ~VEN~ON
This inven~on relates to th~rmal mass t~nsfer imaging. Mo~e par~cularly, this invention relates to transfer of "~Ise c~lor" images using fluorescent pigments.

SU~RY OF Tl~IE I~N
This inven~on relates to ~ermal mass transfie~ p~in~g, particularly thermal mass transfer prin~g using flllorescent mate~ials.
It is a feature of ~e izlvention to pro~ide high quality fluorescent images 5 by way of a thennal mass transfer p~cess by Willg a light ~atteling/light blocl~g opaque whit:e background layer ~o enhance and bnghten ~e flU~YeSCelat image, especially when the image is placed on top of a colored background. ~e the~nal mass transfer donor nbbons of the irlvention are suitable for imaging ap~lica~ons in desktop publishing, direct digital non~ritical color proofing9 and short-run sign 10 manu~acture, for e~ample and is es~ecially useful for fluorescent color generation.
In one aspect the invention discloses a fluorescent thennal mass transfer donor ribbon comprising a subst~te coated on at least a portion ~er~f with a fluorescent colorant containing inlc layer and ano~er por~on or the same por~on is coated thereon with an opaque white background ink layer.
In another aspect the invention discloses a process ~or ~ansfer imaging wherein two layers of material, an opaque white background ink layer and a fluorescent col~rant containing ink layer, are thennally transferred in a single step to a rece~tor film, wherein ~he ~esulting ~ermally ~ansferred fluorescent image is gxposed.
In yet another aspect the invention diss,loses a fluorescent ~ermal mass transfer donor ribbon comprising interspersed patches of a fluorescent colorant containing transfer layer and an opaque white baekground inlc layer.
~ a further asp~ct ~he invention discloses a process ~or ~ans~er imaging comprising the steps of thermally t~ansfemng an o~aque white background in~
25 layer from a donor ribbon to a rece~tor ~heet of film thereby crea~slg a w~ite background image, and thermally transfening a fluorescent colorant ~ntaining inklayer ~rom said donor ~ibbon onto said white background image.

~.J ~ 7 ~

iDETAIL~ ESClR~PllON OF T~3[E INVENIION
Two fluorescent thermal mass ~ans~er donor ribbon constructions are useful in the prac~ce of ~e present invention. In the first embodiment, a ~helmally transfeIable layer containing fluorescent colorant is coated onto a subst~e, andS another thermally ~ansferable layer coneainîng o~que white pigmen~ is ~ver coated onto the first thern~lly tlansferable layer. In ~e s~ond embodim~n~,the ~ermally ~nsferable layers containing opaque white and fluorescent colorants, r~tively, are eoated in an altexna~ng or parallel patch-type manner.
According to one embodiment of the present invention, fluorescent ~ermal 10 mass trans~er donor ribbons of the p~esent invention eomprise a substrate having eoated on at least a portion ~ereof a fluorescent colorant containing ink layer,wherein said fluorescent colorant contait~ing ink layer is coated thereon with an o~aque white background ink layer. In one embodiment of ~he present inven~on fluorescent colorant thermal transfer ribbons are prepared by coating a fluorescent 15 colorant containing ink onto at least a portion of one side of a suitable substrate and coating an opaque white background ink layer onto ~e exposed fluorescent colorant ~ntaining layer. In this embodiment, it is desirable to reduce ~e thickness of the opaque white background ink la,yer to facilitate good thennal mass ~ransfer imaging of both the whi~e and fluores~ent ink layers. To achieve ~is, 20 mixtures of titanium dioxide (nd=2.4) and alun inum o~ide (nd=1.7) are preferably used in ~e opague white background ink l~yer, such 'Ihat the titaniumdioxide and alun~inum oxide are dis~ersed in the opaque white background ink layer. In this way, a high pigment to binder r~tio is obtained impr~ving ~e light scattenng ability of ~e opaque white background layer and permifflng the use of 25 thin opaque white background ink layers.
Fluorescent colorant containing ink layers of the present inven~on comprise a fluorescent colorant and a binder. lPreferably, ~ey are pre~ared by dispersingcolorant in a binder. Opaque white ba~ground ink layers comprise a white pigment in a binder. The binder for either of ~e two embodiment3 of thermally 30 transferable layers comprises at least one of a wa~-like substance and a polymeric resin.

- s -Fluorescent colorants s~table for use in ~e present invention include organic and inorganic fluor~scent dyes and pigments. Non-lirni~ing examples of fluoressent inorganic pigments include ~c sulfide-c~pper mi~tures9 zinc sulfide copper plus cadmium sulfide~opper mi~tures, zinc oxide-zins mi~tures andS ~e like. Notl-limi~g examples of fluo~escent org~s~ic pi~ments inslude LumogenL yellow, Lumog~n L Brilliant Yellow, Lumogen L R~d ~ange; A~ ~X, D, and (}T series D~y-Glo pigments (l~ay-Glo Corp., Cleveland, OH), and the like.
~on-limiting e~amples of fluorescent dyes inrlude ~iofla~ (Colour Inde~ (Cl) 490~5); Basic Yellow B~; (CI 46040); lE~luor~in (CI 45350); Rhodamine B (CI
10 45170); Rhodamine 6G (CI 45160); Posin (CI 45380); and conven~onal white fluorescent bnghteners such as, ~or instance, as CI fluorescent Brightening Agent 85, 166 and 174, fluorescent colorants may be those obtained by rendenng the above mentioned fluorescent dyes oil soluble ~and simultaneously water insoluble) with organic acids such, for instance, as Oil Pink #312 obtained by rendenng 15 Rhodamine B ~il soluble and Barifast Red 1308 obtained by rendering Rhodamine6G oil soluble (produc~d by Orient Chemical Co.). Pluorescent colorants may also be obtained by lake forma~on of the above fluorescent dyes with metal saltsand other precipitants such as, Fast Rose and fast Rose Conc obt~ined by la~e formation of Rhodamine 6G (produced by Daillichi Seika Kogyo K.K.), and so 20 forth.
Although ~e present inven~on may be employed with ultraviolet or infiared fluo~esc~ng colo~n~s, it is preferred that the fluoIescent colorants of ~e presen~ invention should have fluorescence emission in ~e wavelen~ range of 350 to 700 nm, more preferabiy in the range of 400 to 650 nm.
Suitable white pigments include, but are not limited ~o, white metal o~ides such as titanium dio~ide, zinc oxide, aluminum o~ide and hydro~ide, magnesium o~ide, etc.; white me~al sulfates such as bariuJn sulfate, zinc sulfate, calciumsulfate, etc., and white metal carbonates such as calcium carbonate, ete. For op~mal stability and operability of the present invention and thc images formed 30 ~ereby the white pigments should have very low ~lubili~y in wa~ he white pigments may be optionally treated with surfa~e modif~g agents to improve their dispersibili.h,r in the binder.
Suitable wa~ e substances have a melting polnt or softening point of 3~rom about 50 to 140~ C, and include but are not limlted to higher fat~y acid 5 ethanolamin~s such as st~c acid monoetharlo3amide, lau~ic acid mono¢t~olamide, coconut oil monoethanolasnide; higher ~a~ty acid es~ers such as solbi~an higher fat~ acid e~ters such as sorbi~an behenic acid ester; glyc~rine higher fatty acid esters such a~ glycerine morlosteanc ~d este~, acyla~ ~ ols such as acetylsorbitol and benzoylsoxbitol, ~cylated ~itols such as 10 ace~lmannitol; and wa~ces such as beeswa~, parafi'in w~, carnauba wa~, Chlorez wa~es, etc.; and mixtures thereof. Preferred wa~-like matenals ;nclude stearic acid monoethanolamide (mp 91-95 C), lauric acid monoe~anolan~ide (mp 80-84 C), coconut oil fatty acid monoethanolamide (mp 67-71 C), so~bi~an behenic acid ester (mp 68.5 C3, sorbitan stearic acid ester (mp 51 C), glycerine 15 monostearic acid ester (mp 63 - 68 C), acetyl sorbitol (mp 99.5 C.3, benzoyl sorbitol (mp 129 C), and acetyl mannitol (mp 119-120 C).
Suitable polymeric resins have melting or sohening points in the range of about 20 to 180 C, preferably in the range ~f 40 to 140 C, more pre~erably in the ~nge of 55 to 120 C, and most pre~e~ably in ~he range of 60 to l~P
20 C and include, but aI`R not limited to, polycaF~rolactone, polyethylene glycols, aromatic sulfonamide resins, acrylic resins, polyamide resins, polyvillyl chloride and chlonna~ed polyvinyl chlo~ide resins, Yinyl chlo~ide-vinyl a~etate copolymers, allyd resins, urea resins, melamine resins, polyolefins, benzoguanamine resins and copolycondensates or copolymers of th~ aboYe resin materials. Prefe~ed polymeric25 resins a~e polycaprolactones llaving an average molecular weight of 10,000 g/mol (mp 60-65 C) polyethylene glycols having an ave~ge molecular weight of ~00 g/mol (mp ~ 62 C), low condensa~on polymerized melals~ine toluenesulfonamide resins (sp ~ 105 C), low co~densation polymeri~ed benzyltoluene sul~onamide resins (sp ~68 C), acrylic resins (s~ ~85 C), and linear polyami~e resins 30 ~sp ~60 C). l~e terms "mp" and "sp" lrefer to "mel~ng point" and "softening point," respectively.

Preferably, ~he fluore~nt colorant containing ink layer and opaque whi~e backgr~und ink layer have a mel~ng point (mp) or softening point (sp) of 50-140 C eo enhance the thermal t~sfierril~g property.
Suitable subs~ate mater~ls for the thermal mass ~ansfer donor elemen~
S anay be any fle~ible material to which a fluoresc}~n~ colorant containing ink hyer may be ~dhered. Sui~able subs~a~s may be smooth or rough, t~ans~nt, opaque, and cl)ntinuous- or sh~e~-like. They may be ess~n~ally non-p~rous.
Preferred baclcings are white-filled or transparent p~yethylene ter~ alate or ~paque paper. Non-li~ting e~nples ~ materials ~hat a~e suitable for use as a 10 substrate include polyesters, especially polyethylene ~ereph~ala~e, polyethylene naphthalate, polysulfones, polys~renes, polycarbonates, polyimides, poly~des~
c~llulose esters, such as cellulose acetate and cellulose butyrate, pol~yl chlo~ides and deriva~ves, etc. The substrate generally has a thicklless of 1 to 5 s~m, preferably 2 to 100 ~m, more prefe~ly 3 to 10 ~m.
By "non-p~rous" in the description of t~le invention it i~ meant that ink, paints and other liquid eoloring medla will nvt readily flow ~rough the substrate (e.g., less than 0.05 ml per second at 7 torr appllied vacuum, pre~erably less ~an 0.02 ml per second at 7 torr applied vacuum). The lack of significant porosi~
prevents absorption of the heated rec~ptor layer into the substrate.
In another embodiment of the present invention fluorescent thermal mass transfer ribbons are prepargd by coa~ng a fluorescent ~lorant conta ining ink layer and an opaque white background ink layer onto one side of a sui~le substrate in a patten~ such that the two ink layers are inters~rsed in a manner so that the area of ~e substrate covered by each ink layer is substantially equal. The white and ~5 the fluorescent image may be identi~ (coe~tensive în all direction)~ substan~ally overlap, eompletely overlap, outline one another, or border e~ch sther.
The fluorescent t~ermal mass transfer ~ibbons of the present inven~on are generally employed in combination with a ~ce~tor sheet in a process for transfe~imaging wherein t~vo layers of mateAal, an opaque white bac~ground ink layer and30 a fluorescent eolorant containing ink layer, are transfe~ed in a single step or s~uential steps.

The fluores~ent ~ermal transfer donor nb~ns of the inven~on are suitable for hTIage pr~duction in deskt~p publishing, di~t digital non-cri~cal c~lor proofing, shor~ un sign manufiacture, and so forth, especially for graphics desinng fluorescent color generation.
S Coating of ~e thennally bansferable layers on ~e donor sheets may be accomplished by many standa~d we~ ng t~hnigues such as imprint g~a~, single or double slot e~ctrusion c~a~ng, ~nd the like. Impnnt gravure is pa~icularly use~l for patch-t~ coa~ngs in whish ~ere are interspersed regions of opague white and fluorescent coloMnts on a ribbon or sheet. Layer coa~ng ~ichlesses useful in the presen~ invention are 0.1 to 50 ~m, pIeferably 0.5 to 10 ~m, most preferably 1 to 6 ~m.
The donor ribbons of the presen~ invention are generally used in ~ermal printing by con~acting the transferable layer of ~e donor ribbon ~th a ~eceptor sheet or film such that at least one thermally ~ansfelable donor layer is in contact 15 with the receptor sheet. Heat is a~lied, either f~m a ~he~al s~lus or an infrar~d heat source sucl~ as an infrared laser or a heat larnp and the donor layer is trans~erred to the receptor. The heat may be applied to the back of either ~e donor ~ibbon or receptor sh~et or may be directly introduced to a ~ansferable donor layer.
Preferred r~ceptor sheet materials are .Dai Nippon Type I and Type V
receptor films (Dai Nlppon Insatsu K.K., Tokyo, Japan), Dupont 4-Cast r0ce~tor film (E.I. I)upont de Nemours Co., Wiln~ington, DE), Scotchcal film (3M Co., St. Paul, MN), and polyethylene terephthalate. The rece~tor ~eets may be color~d, that is they may have an optical density of at least 0.2 in the visible25 region of the electromagne~c sp~trum.
In a preferred embodiment a release coa~ng is ap~ e back side of the donor ribbon (i.e., the side ~osite the thermally ~ansfeIable donor layer(s)) to improve handling charactens~es of the Iibbon and reduse fric~on. Suitable release materials include, but ~re not limitod to, silicone m~terials including 30 poly~ower alkyl)siloxanes such a~ polydimethylsilo~ane and silicone-urea copolymers, and perfluon3lated compounds such as perfluoro~olygthers.

9 ~ $1~
The following examples fur~er illustrate practiee of t!he present invention and should not be considered li~ng.

CO~ARATIV~ BXAMPLlE
~his compara~e es~ample dem~llshates ~e pr~para~on of a fluores~nt colo~ant donor ribbon and formation of fluorescent images on v~ous rece~or films by ~erlTIal bransfer.
A ~olu~don of fluorescent pigment consis~ng of 9 par~s GT series Auro~a Pink pigment (I)ay-Glo Co~p., Cleveland, OlE31), 9 p~rts Chlo~ow~ 70 (a 10 chlonnated paraffin wa~, mp 10~ C, obt~ed ~rom Occidental Pet~ um t:o., Irving, TX), and 1 part Acryloid B82 (an acrylic resin, Tg=35 C9 obtained from l~ohm and Haas, Philadelphia, PA) w~s mi~ced in a ball mill for 1~15 hr.
Then 7.5 parts of a beeswa~ solution in toluene added with ~g to give a coa~ng solution that was 30% solids in toluene. The r~sultant solution was coat~d 15 approximately 5 ~m thick onto 6 ~m polye~yle~e tereph~alate (PET) lSlm. Ihis coat was dried ~or approxîmately 2 minutes at '~ C.
I~ennal transfer of this film w~s demonstrated with four r~to~
materials: ~a) Scotchcal film (3M Co., St. Paul, MN) at ap~ro~mately 1.6 J/cm2 using a thermal prin~er capable of 200 dot per inch (dpi) resolution. The resul~ant 20 ~ransferred image had slightly uneven edges on the dots at 200 dpi res~lution; (b) 76 ~m PET film (at appro~imately 1.6 J/cm2 us~ing the same thermal ~inter as in (a), a resolution of 200 dpi f~r the t~ansferr~d image alS~ough dots at 200 dpi were slightly uneven; (e) Type I and Type V Oai Nippon dye ~ansfer r~eptor~ ~I)ai Nippon Insatsu K.K~, To~o, Japan) at approxîmately 1.6 J/cm2 using the same 25 thermal printer as in (a~, transferred dot images at 200 dpi were sligh~y uneven.
It was visually noted tllat the ~ans~e~ uorescent pigment images lost much of their fluorescence when coated ~Yer a non-white background.

This exalalple demonstrates the prel~ation of a Iquorescent pigment donor ribbon construction consis~ng o~ a substrate coat~d sequen~ally wi~ fluaresoent pigment containing l~yer and an ~paque wl~te layer.
A fluorescent pigment solution was mi~ed as in the Comparative Example.
It was coated appro~imately 3 ~m ~i~ onto 6 ,um PET. It was d~ied o~imately 3 ~inutes a~ 70 C. Then a ~olu~don of 8 pa~s TiO2 (ave~age ~r~cle size < 100 nm3, 1 part Acryloid ~82 (an a~ylic re~in, Tg=35 C, obtained from Rohm and Haas, Philadelphia, PA), and 1 ~rt DeSoto E-335~ lan 10 acrylic resin from DeSoto Inc., Des Plaines, lL) was grolmd in a ball mill for 5-10 hours. Ihen 3 parts beeswa~c in toluene was added with ~g. This solution (30 wt% in solids in toluene) was coa~d appro~ima~ely 2 ~m thick o~ver ~he fluoresc~nt layer. This entire film was dried 3 n~inutes at 70 C.
This film was printed onto ~he Dai ~ippon dye Type I bransfer receptor 15 sheet at appro~l;imately 1.6 J/cm2 using the thermal p~inter ~ ~e Compara~Ye Example at a resolu~don of 200 dpi.
The resultant hansferr~d fluorescent image was visually dete~ned to have improved color cla~i~y compared to t~e images ~ e Comp~ ve Example.

This example demonstrates an alternate p~ting method in which an opaque white layer is pAnted and then overp~inted with fluorescent ma~erial.
A solution of flu~escent pigment was mi~ed as in the Comparative E~ample. Ihis solu~on was co~ out at appIoximately S ~m onto 6 ~m PET
25 film. This ~lm was dried 3 minutes at 70 C.
Another mi~ture of 8 parts Ti(:~2 (average p~uficle size ~ 100 nm) and 2 parts l~kSoto ~-338n' ~an acrylie resin, ~tained frGm DeSoto Ine., Des Plaineg, IL) was mi~ed in a ball mill for 8-10 hours. Th~n 3 p~rts beeswax s~lution in toluene was added with mLlcing. This solu~on (30 wt% solids in t~luene) was 30 coat~l at 4.5 ~m onto another 6 ~m PET film. This film was dried 3 minutes at70 C. First the white layer was p~inted onto a Dai Nippon Type I rece~tor shee~, . . .
,~
, .

2 ~ 7 ~

followed by over-prin~ng of the fluorescent pigment layer. Both t~ansfer ste~s were performed at ap~ro~ima~ely 1.6 J/cm~ USillg the thennal printer of ~he Compara~ve Ekample at a resolu~on of 2~ dpi.
n was ~sually determined ~at ~e fluoreseence was much be~ter ui~ the 5 white layer than without it.

EXAMPL~ 3 This e~arnple demonstrates a two l~yer construc~on wherein an opaque white backgrour.d ink layer is coated on a fluorescent ~lorant containing ink layer 10 support~d by a substrate.
I WO dis~ersions, one opaque w~ite and one fluoresoent, were p~red and dispers~d as 30 wt% solids in 9:1 toluene/bu~ te solvent. The fluoressent s~lution consisted of 4 parts AX seAe3 Aurora Pink ~Day-Glo Corp., Clevelarld, C)H~ and 1 pal~ Acryloid ~66 (an ac~c resin, Tg=50 C, ~ohm and ~as, 15 Philadelphia, PA). Ihe opaque wl~ite dispcrsion was prepar~d by combining 6 parts titanium dioxide (sub-micron average particle diamet~r), 2 parts Spa~ RiteS-ll alumina (a 0.25-0.3 ~m ~verage particle size alun~inum t~ihydrate, Alc~a Colp., Bauxite, A~), 1 part Elvacite 20Q8 (an acrylic resin, Tg=105 C, obtained from E.I. DuPont de Nemours Co., Wilmington, D~l), and O.S parts 20 EHEC low (an ethyl hydro~yethyl ~llulose wi~ extra low viscosity, flow temperature :~ 175 C, obtained from Dow Chemical Co., Midland, MI). E~ach dispersion was independently mi~d in a ball IDill for 6 to 10 hr.
The fluore~nt layer was coated onto 6 ym polyethylene terephthalate film at 8.33 ~m wet thickness using a num~r 5 l~eyer bar (R&D Special~ Webster, 25 NY). Il~e coa~g was air dried i~or 2 rninutes then the o~aque white layer wascoated on top of the fluorescent layer at a S ~m wet ~ickness using a number 3 Meyer bar. The coated film was oven dried for about 2 min at 70 C.
Ima~e ~ransfer was ~ceomplished using the ~e~mal prillter of ~e Compara~ve E~ample wherein d e opaque white and fluorescent laye~ were 30 transferred simultaneously using a ~erma,l energy of 3.8 ~/cm2. Ihe fluorescent image had go~ color clari~ as judged by eye and a resolu~on o~ at least 200 dpi.

..

This example demonst~ates a ~tch-typç coa~ng construction. Fluorescent dispersions in toluene we~e pre~red ~ording to the metho~ of the Compuative ~cample in amounts describ~d in Table 1, and alte~nately ~oated with an opaque 5 white dispersion according ~e me~hod of E~ample 5 in amolmts described in Table 1 onto 6 ~m thi~c, 9 inch wide polyethylene tereph~alate film in 13 inch long patches and oven dried ~wo to 3 nninutes at 60 to 80 C. I'~le ~ermally ~ansferable flu~rescent films thus prepared were imaged onto Dai Nip3pon Type V re~e~tor film using ~e ~ermal print~r of ~e ComparatiYe lixample 1.

Table 1. Fluorescen~ Patch-l~e ~he~mal T~ans~er Prin~ng Fluore~cçnt Lay~r Composition Thiclmess ~ ~eMIl kground Layer Composi~on ~m) Ene~gy Im~ge (J/cm2) Quality __ GT-1 1/CI-wax 70/B 82 (9/911) S.5 2.43 good to S TiO2/Cl-wa~ 70i~82 (91911) 5.5 ~r GT-11/Cl-wa~c 701B-82/B44S (9191111) 5.5 2.43 very Tit)2/E-333/E-337 (8/1/1) 5.5 good ~3T-ll/B-82/Cl-wa~ 70 (81212) S.5 2.75 i~air to TiO2/E-333/E-337 (8/1/1) 5.5 g~d GT-ll/Cl-wa~ 70/B-B2/C-lOLV/Elva~ 5.5 3.43 very (9/9/11.51.5) TiO2/E-333/E-337 (8/1/1) 5.5 GT-11/Cl-wax 70/B-82/C-lOLV/~ilva~c~ 5.5 3.43 good (gl51.51211) TiO2/E-333/Ei-337 (8/1/1) 5.5 GT-11/Cl-wa~ 70/E-337/Elvax~ (9151311) 5.5 2.43 go~d TiO2/E-333/E-337 (8/1/1) 5.5 A-19/Cl-wax 7û/~i-337/Elvax~ ~9151311) 5.6 2.43 g~d TiO2/E-333tE-337/Elva~ (811111.5) 5.5 resoluti on GT-11/Cl-wa~ 70/E-337/E~va~n' (9151311) 5.6 2.43 good TiO2/E-333/E-337/Elva~'Y (811/11.5) 5.5 resolu~
nn GT-11 (Aur~ra Pink, Day-Glo C~IP.), A-19 (Horizon Blue, Day-~lo Co~p.), Cl-wa~ 70 (Chlorowa~TU 70, Occidental Chemîcal Co.), B-82 (Acryloid B82, RDhm a~d HaalS)3 B~445 (Acryloi~ BWS, Rohm 2nd Haas~, E-333 (modified ~crylic resin E-333, DeSoto - 14~

A sample of 5 parts ~tanium dioxide (sub-micron ~verage particle diameteF) 3 parts Space Ri~ S-ll alu~ (a 0.25~3~m ave~age particle size aluminum ~ihydrate), 3 parts Carboset XL-ll (an acrylic ~esin, Tg--~5C, obtained ~rom 5 B.F. G~drich Company, Cleveland, O~ and 2 parts Cab~Sil MS (an amorph~us fumed silica, Cabot Corpo~ation, Tuscola, IL) was disp~rsed 30% in isoprvpyl alcohol by milling in a ball mill for ~10 hours.
Another sample of 8 parts AX senes Aurora Pink ~!Day-Glo Co~p., Cle~eland, ~I3, 1 parts C~boset XL-ll (an ac~ylic r~in, Tg=55C, 10 B.F. Goodrich Co., Goodrich Company, Cl~veland, OH) was dispersed 30% in isopropyl alcohol by high-sp~d (pr~ellor) mL~ing for 10 minutes.
The fluorescent layer was coated onto 6~m P~iT film at 8.33 ~m wet ~ickness using a number S Meyer Bar (R&D Specia1ties, Web~te~, NY). The coating wa~ air dried for 3 ~utes, ~en the opaque layer was coated on top of 15 ~e florescent layer at a S ~m wet thichless using a number 3 Meyer ~ he film was oven dried for about 5 minutes at 70C.
Image t~ns~er was aecomplished using the thermal printer of the Compara~ve Example wherein the ~paque white and flo~escent layer were transferred simuleaneously using a the~mal energy of 3.8 J/cm~. The ~ escent 20 image had good color clarity as judged by eye and a resolu~on of at least 2~ dpi.

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Claims

1. A thermal mass tranfer donor element comprising a substrate having coated thereon a thermally transferrable fluorescent colorant and a thermally transferable opaque white material.

2. The donor element of claim 1 wherein said fluorescent colorant comprises a layer on said substrate and said opaque white material comprises a layer overcoated on said fluorescent colorant.

3. The donor element of claim 1 wherein said fluorescent colorant comprises patches of colorant on said substrate and said opaque white material comprises patches of colorant on areas of said substrate where said fluorescent colorant is not present.

4. The donor element of claims 1, 2 or 3 wherein said opaque white material comprises white metal oxides, white metal sulfates, or white metal carbonates.

5. The donor element of claims 1, 2 or 3 wherein said opaque white material is mixed with a wax or polymeric resin.

6. The donor element of claim 4 wherein said opaque white material is mixed with a wax or polymeric resin.

7. A process for providing a fluorescent image on a receptor surface comprising thermal mass transferring a white image onto a receptor surface and thermal mass transferring on top of at least part of said white image a fluorescent image.

8. The process of claim 7 wherein said transferring of said white image and said fluorescent image are performed at the same time.

9. The process of claim 7 wherein said transferring of said white image and said fluorescent images are performed sequentially.

10. The process of claim 7 wherein said white image and said fluorescent image substantially overlap, and said white image and said fluorescent image are substantially the same.