(19) TZZ__Z_T

(11) EP 1 987 107 B1

(12) EUROPEAN PATENT SPECIFICATION

(45) Date of publication and mention (51) Int Cl.: of the grant of the patent: C09D 11/00 (2006.01) C08K 5/09 (2006.01) 23.01.2013 Bulletin 2013/04 (86) International application number: (21) Application number: 04817451.0 PCT/US2004/035531

(22) Date of filing: 25.10.2004 (87) International publication number: WO 2005/042654 (12.05.2005 Gazette 2005/19)

(54) INK COMPOSITIONS FOR USE IN HIGHLIGHTER MARKERS AND ASSOCIATED METHODS TINTENZUSAMMENSETZUNGEN ALS ZUSATZ ZU MARKIERSTIFTEN UND ENTSPRECHENDE VERFAHREN COMPOSITIONS POUR MARQUEURS DE SURLIGNAGE, ET PROCEDES ASSOCIES

(84) Designated Contracting States: (74) Representative: Beccarelli, Sandra Béatrice DE FR GB Yvonne IP Section (30) Priority: 29.10.2003 US 696344 Hewlett-Packard Limited Long Down Avenue (43) Date of publication of application: Stoke Gifford 05.11.2008 Bulletin 2008/45 Bristol BS34 8QZ (GB) (73) Proprietor: Hewlett-Packard Development Company, L.P. (56) References cited: Houston, TX 77070 (US) EP-A- 1 239 014 WO-A-97/31070 WO-A-02/061003 US-A- 5 279 562 (72) Inventors: US-A- 5 462 592 US-B1- 6 436 178 • SCHMID, Christian, US-B1- 6 458 193 16399 W. Bernardo Drive San Diego, California 92127-1899 (US) • PATENTABSTRACTS OF JAPAN vol.012, no. 283 • STOFFEL, John L., (C-518), 3 August 1988 (1988-08-03) -& JP 63 16399 W. Bernardo Drive 061065 A (PENTEL KK), 17 March 1988 San Diego, California 92127-1899 (US) (1988-03-17) • SPERRY, Bill • PATENT ABSTRACTS OF JAPAN vol. 1996, no. San Diego, California 92128 (US) 08, 30 August 1996 (1996-08-30) & JP 08 108682 A (TOPPAN PRINTING CO LTD), 30 April 1996 (1996-04-30)

Note: Within nine months of the publication of the mention of the grant of the European patent in the European Patent Bulletin, any person may give notice to the European Patent Office of opposition to that patent, in accordance with the Implementing Regulations. Notice of opposition shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention). EP 1 987 107 B1

Printed by Jouve, 75001 PARIS (FR) 1 EP 1 987 107 B1 2

Description sitionsof thepresent invention canbe applied to an image on a substrate. In one detailed aspect, the image can be FIELD OF THE INVENTION formed on the substrate by ink-jet printing an ink-jet ink. Application of the highlighter ink compositions of the [0001] The present invention relates generally to high- 5 present invention to a printed image results in a reduced lighter ink compositions. More particularly, the present degree of image smear. In yet another aspect of the invention relates to components used in highlighter mark- present invention, the highlighter ink composition can in- ers to reduce smearing of ink- jet ink text or images upon clude an acid buffer, such that the acid buffer is config- highlighting. ured for reducing mobility of an ink-jet colorant. In this 10 way, the highlighter ink composition can be specifically BACKGROUND OF THE INVENTION tailored for reducing smear of ink-jet printed ink(s). [0006] Additional features and advantages of the in- [0002] Highlighters have become a popular way of vention will be apparent from the detailed description that marking printed media such as text and/or images in both follows, which illustrates, by way of example, features of educationaland professional settings. Avariety of printed 15 the invention. media are commonly printed using techniques such as laser printing, offset printing, ink- jet printing, and the like. DETAILED DESCRIPTION Ink-jet printing offers a versatile and inexpensive way to print text and/or images. However, ink- jet printed images [0007] In describing and claiming the present inven- can be subject to undesirable smearing and poor water- 20 tion, the following terminology will be used. fastness. One common problem with ink-jet inks is that [0008] The singular forms "a," "an," and "the" include of smearing when using a highlighter to mark an image. plural referents unless the context clearly dictates other- Specifically, the solvents in the highlighter ink can cause wise. Thus, for example, reference to "a highlighter col- a portion of the colorants of the ink- jet composition to be orant" includes reference to one or more of such mate- displaced. This results in moderate blurring of the image 25 rials and/or undesirable colored streaks in the highlighted ar- [0009] As used herein, "acid buffer" refers to a chem- ea. Additionally, some of the ink- jet ink can be transferred ical compound or compounds in a composition which act to the highlighter, damaging the marker tip. to maintain the pH in a desired acidic range. Typically, [0003] The ink-jet industry has attempted to reduce such acid buffers can include a weak acid and a corre- these effects using a number of techniques. One com- 30 sponding conjugate weak base. Upon the addition of an mon method is to develop ink-jet ink compositions that acid or a base, properly selected acid buffers will allow are smear resistant and exhibit improved waterfastness. only minor changes in pH of a highlighted image. A number of these attempts have seen moderate suc- [0010] As used herein, "fluorescent colorant" refers to cess; however such methods often introduce additional a colorant having a fluorescent color. Fluorescent colors costs and steps in the production of the ink- jet ink. Other 35 are those which exhibit luminescence in the form of vis- approaches for reducing smear of printed images have ible radiation. Fluorescent colorants can include dyes, attempted to design highlighter markers with a physical pigments, and the like which provide such visible color construction that minimizes smear. For example, the to a composition. highlighter tip shape and/or material can be modified to [0011] As used herein, "pKa" is related to add dissoci- reduce smear. However, such methods often require a 40 ation, and can be used to quantify the strength of an acid. change in tooling for manufacturers, which may not al- Specifically, pKa is the pH at which half of the acid is ways be desirable. For these and other reasons, the need dissociated and half of the acid is not dissociated. Strong still exists for improvedmethods for reducing smear when acids generally have a pKa less than 3, and weak acids highlighting ink-jet text and images. typically have a pKa greater than 3. [0004] WO0206103 describes a marking liquid, used 45 [0012] As used herein, "print smear" refers to a move- to emphasise texte, comprising a salt solution and a ment of printed colorants on a substrate, which reduces colored polymer dispersion. edge acuity and sharpness of printed images. In context of the present invention, print smear is frequently asso- SUMMARY OF THE INVENTION ciated with highlighting of a previously printed image. 50 Typically, print smear can be measured using a visual [0005] It has been recognized that it would be advan- scale of 0% to 100% acceptable appearance of an image tageous to provide improved abilities to reduce smear based on the perceived degree of smear. during highlighting. In one aspect of the present inven- [0013] As used herein, "mobility" refers to the extent tion, a highlighter ink composition can include an acid of movement of printed colorants on a substrate which buffer having a pKa from 2 to 6, a highlighter colorant, 55 are subjected to highlighting. Unless otherwise noted, selected from the group consisting of Basic Yellow 40, mobility refers to movement after drying and printing of Acid Yellow 23, Acid Red 52, Acid Blue 9, and mixture the image and during application of a highlighter ink com- thereof; and a liquid vehicle. The highlighter ink compo- position.

2 3 EP 1 987 107 B1 4

[0014] As used herein, "image" refers to marks, signs, connection with marking of specific ink-jet inks. Accord- symbols, figures, indications, and/or appearances de- ingly, the present invention provides improved smear re- posited upon a substrate with either a visible or an invis- sistance during marking of printed images using the high- ible ink composition. Examples of an image can include lighter compositions of the present invention. characters words, numbers, alpha-numeric symbols, 5 punctuation, text, lines, underline, highlights, and the like. Acid Buffer [0015] As used herein, the term "marker" or "highlight- er" includes any contact instrument or device that can be [0021] The highlighter ink compositions of the present used to overstrike a printed image, and is not intended invention can include an add buffer having a pKa from 2 to merely include a single type of marking device. In de- 10 to 6. In one detailed aspect, the acid buffer can have a scribing certain embodiments, when referring to the use pKa from 4 to 6. Suitable acid buffers can include, without of a highlighter, it is not to be inferred that such a device limitation, succinic acid, citric acid, glutaric acid, acetic is the only type of over-striking device that can be used. acid, beta-alanine, aspartic acid, ascorbic acid, and mix- [0016] As used herein, "liquid vehicle" is defined to in- tures thereof. In one embodiment of the present inven- clude liquid compositions that can be used to carry an 15 tion, the acid buffer can be succinic acid. acid buffer, highlighter colorant, and/or other compo- [0022] The acid buffer can comprise any amount of the nents to a substrate Liquid vehicles are well known in the highlighter ink composition which is functional to obtain art, and a wide variety of liquid vehicles may be used in the desired degree of smear reduction. However, as a accordance with embodiments of the present invention. general guideline, the acid buffer can comprise from 0.5 Such liquid vehicles may include a mixture of a variety 20 wt% to 10 wt% of the highlighter ink composition. In one of different agents, including without limitation, sur- detailed aspect, the acid buffer can comprise from 3 wt% factants, solvents, co- solvents, buffers, biocides, viscos- to 8 wt% of the highlighter ink composition. In another ity modifiers, stabilizing agents, complexing agents, and detailed aspect, the acid buffer can comprise from 2 wt% water. Though a variety of agents are described that can to 3 wt% of the highlighter ink composition. be used, the liquid vehicle, in some embodiments, can 25 be simply a single liquid component, such as water. Fur- Highlighter Colourant ther, unless specifically stated otherwise, all concentra- tions and composition values are given in weight percent. [0023] In accordance with the present invention, the [0017] As used herein, "effective amount" refers to at highlighter ink compositions can include a highlighter col- least the minimal amount of a substance or agent, which 30 orant. The highlighter colorant can provide a bright and is sufficient to achieve a desired effect For example, an easily identifiable color to the ink. Any suitable highlighter effective amount of a "liquid vehicle" is at least the min- colorant can be used in the compositions of the present imum amount required in order to create an ink compo- invention and can be almost of almost any color, either sition, while maintaining properties necessary for effec- fluorescent or non-fluorescent. For example, though a tive application or ink-jetting. 35 typical highlighter color is yellow, other colors can be [0018] Further, the term when referring to a numerical used, e.g., orange, blue, red, green, pink, purple, and value or range is intended to encompass the values re- combinations of these colors. Non-limiting examples of sulting from experimental error that can occur when tak- several suitable highlighter colorants include Basic Yel- ing measurements. low 40, Acid Yellow 23, Acid Red 52, Acid Blue 9, and [0019] Concentrations, amounts, and other numerical 40 mixtures thereof. Further, although some of the highlight- data may be presented herein in a range format. It is to er ink colorants can be acid dyes, the addition of an acid be understood that such range format is used merely for buffering agent in accordance with the present invention convenience and brevity and should be interpreted flex- can further reduce smearing of images during highlight- ibly to include not only the numerical values explicitly ing. recited as the limits of the range, but also to include all 45 [0024] In one aspect, the highlighter colorant can be a the individual numerical values or sub-ranges encom- fluorescent colorant which can be a pigment or a dye. passed within that range as if each numerical value and Suitable fluorescent pigments can be either dispersed in sub-range is explicitly recited. For example, a concen- aqueous or organic liquid vehicles, In one additional as- tration range of 1 wt% to 20 wt% should be interpreted pect of the present invention, the fluorescent colorant to include not only the explicitly recited limits of wt% and 50 can be an acid-funcfionalized pigment. Suitable fluores- 20wt%, butalso to include individualconcentrations such cent pigments are typically available as a powder of a as 2 wit%. 3 wt%, 4 wt%, and sub-ranges such as 10 transparent synthetic resin matrix having a fluorescent wt% to 15 wt%, 2 wt% to 10 wt%, etc. dye dissolved therein together with other optional com- [0020] In accordance with the present invention, a ponents such, as ultraviolet radiation absorbers. Solution highlighter ink composition can include an acid buffer 55 type fluorescent pigments are commercially available, having a pKa from 2 to 6, a highlighter colorant, and a and include, MPI pigment series (available from Nippon liquid vehicle. The highlighter ink compositions of the Keiko Kagaku K.K.) such as MPI-501, 502, 503, 504, present invention can further be configured for use in 505, 506, 507, 508, 501C, 503C, 504C, 505C, 506C,

3 5 EP 1 987 107 B1 6

507C and 508C; FM-10 and FM-100 series (available of 3 to 6. In one embodiment of the present invention, from Sinloich Co., Ltd.) such as FM-11, 12, 13, 14, 15, the specific desirable pH range can be related to the ink 16, 17, 18, 25, 27, 103, 104, 105, 106, 107 and 108; and used to print the image. Specifically, the image can be Flare 410 series (available from Sterling Industrial Col- formed using any known printing technology such as, but ours Ltd.) such as 41031 Yellow, 41035 Rose, 41037 5 not limited to, offset, ink- jet, laser, gravure, roller coating, Magenta, 41022Brightener and 41022N Brightener. Oth- screen printing or other application methods known to er commercial fluorescent colorants include PANAX flu- those skilled in the art. Further, the images can be hand- orescent pigments (available from Ukseung Chemical written images using any number of known inks. A wide Co., Ltd.) and AQ series of water soluble pigments (avail- variety of inks are known for creating images using the able from Cardinal Color Inc.). 10 above printing techniques. Of particular interest are im- [0025] Further, fluorescent colorants can be fluores- ages printed using ink- jet inks. Despite continued efforts cent dyes which are dispersed within or soluble in an to improve waterfastness of ink-jet inks, such composi- organic resin. Additionally, the fluorescent colorants can tions are significantly more susceptible to smearing than be used either singly or as a mixture to produce a wide laser toner inks, offset inks, and the like, each of which variety of colors or to effect properties of the highlighter 15 typically include a polymeric binder. A great deal of effort ink composition, such as pH and the like. is expended in preparing ink-jettable compositions that [0026] The highlighter colorant can be included in the are stable during storage in an ink-jet cartridge and also highlighter ink composition of the present invention in have good waterfastness properties upon printing. For- any amount that is sufficient to provide a visible color to mulation of such ink-jet inks is often a careful balance of the composition when applied to a substrate. The amount 20 permanence after printing; as well as reliability and long- of highlighter colorant which is sufficient to provide a term storage prior to printing. strong visible color can vary significantly depending on [0030] Ink-jetting techniques generally involve deposi- the specific colorant. Typically, the highlighter colorant tion of an ink-jet ink onto a printing surface using contin- can comprise from 0.5 wt%.to 20 wt% of the highlighter uousink depositor drop- on-demandink depositsystems. ink composition. In one detailed aspect of the present 25 Regarding drop-on-demand printing systems, the ink- jet invention, the highlighter colorant can comprise from 1 inks are typically based upon water and solvents such wt% to 10 wt% of the composition. as glycols. Essentially, with these systems, ink droplets are propelled from a nozzle by heat or by a pressure Additional Composition Considerations wave such that all of the ink droplets ejected are used to 30 form the printed image. [0027] The highlighter ink compositions of the present [0031] In general, ink-jet inks are either dye- or pig- invention can be configured to reduce smear of a printed ment-based inks. Both are typically prepared in an ink image during highlighting. Each of the components of the vehicle that contains the dye and/or the pigment. Dye- composition can potentially influence the effectiveness based ink-jet inks generally use a liquid colorant that is of achieving a desirable degree of smear reduction. 35 usually water-based to deposit a specific color onto the [0028] One component of the present invention which medina. Conversely, pigmented inks typically use a solid can affect the degree of smear reduction is the liquid or dispersed colorant to achieve color. vehicle. As mentioned above, the liquid vehicle can in- [0032] Ink-jet ink compositions are typically prepared clude almost any liquid capable of carrying the highlighter in an aqueous formulation that can include water, cosol- colorant and acid buffer to a substrate. Typically, the liq- 40 vents, surfactants, buffering agents, biocides, seques- uid vehicle can evaporate or dry within a short period of tering agents, viscosity modifiers, humectants, binders, time, leaving the colorant on the substrate. In some em- and/or other known additives. The type of ink-jet pig- bodiments, it is desirable that the liquid vehicle evaporate ments that can be used is not particularly limited, as in- or dry in less than several seconds. However, the liquid organic pigments or organic pigments may be used. vehicle can also be carefully chosen so as to also pre- 45 Common inorganic pigments include, for example, tita- serve a commercially viable shelf-life for the highlighter nium oxide, cobalt blue (CoO-Al2O3), chrome yellow ink composition. Additionally, a liquid vehicle which re- (PbCrPO4), and iron oxide. Several common organic pig- mains on the substrate for extended periods of time can ments include, for example, azo pigments, polycyclic pig- allow for undesirable mobility of the printed colorants and ments (e.g., phthalocyanine pigments, perylene pig- can cause excessive curling of some substrates. Non- 50 ments, perynone pigments, anthraquinone pigments, limiting examples of suitable solvents for use in a liquid quinacridone pigments, dioxazine pigments, thioindigo vehicle can include water, diethylene glycol, polyethyl- pigments, isoindolinone pigments and quinophthalone ene glycol, glycerol, dipropylene glycol, propylene glycol, pigments), dye chelates (e.g., basic dye type chelates polypropylene glycol, 2-pyrrolidinone, and mixtures and acidic dye type chelates), nitropigments, nitroso pig- thereof. 55 ments, and the like. The above-illustrated pigments can [0029] In an additional aspect of the present invention, be used singly or in combination of two or more. the acid buffer can be configured such that upon contact [0033] Colored ink- jet dyes which can be used include, with a printed image, the pH is maintained within a range without limitation, anionic water-soluble dyes and their

4 7 EP 1 987 107 B1 8 ions, and any other known dyes. Though any effective in an ink-jet ink for use in conjunction with the highlighter amount of dye can be used in this system, the dye can ink compositions of the present invention. As is well be an anionic dye. Examples of suitable anionic dyes knownin the art, typical colored ink- jetcolorants can com- include a large number of water-soluble acid and direct prise from 0.1 wt% and 25 wt% of the ink- jet ink, and can dyes. Specific examples of anionic dyes include the Pro- 5 often be present at from 2 wt% and 10 wt%. Jet series of dyes available from Avecia Ltd., Aminyl Bril- [0035] Various buffering agents are also often used in liant Red F- B (Sumitomo Chemical Co.), the Duasyn line ink-jet ink compositions. Depending on the specific ink- of "salt-free" dyes available from Hoechst, and mixtures jet colorants used in the ink-jet inks, the pH can be buff- thereof. Further examples include Tricon Acid Red 52, ered to maintain a value from 4 to 9. Buffering agents Tricon Direct Red 227, and Tricon Acid Yellow 17 (Tricon 10 can be either organic buffers or inorganic buffers. Typical Colors Incorporated), Bemacid Red 2BMN, Pontamine buffering agents include such pH control solutions as hy- Brilliant Bond Blue A, BASF 34, X- Pontamine, Food droxides of alkali metals and amines, such as lithium hy- Black 2, Catodirect Turquoise FBL Supra Conc. (Direct droxide, sodium hydroxide, potassium hydroxide; citric Blue 199, Carolina Color and Chemical), Special Fast acid; amines such as triethanolamine, diethanolamine, Turquoise 8GL Liquid (Direct Blue 86, Mobay Chemical), 15 and dimethylethanolamine; alkali phosphates such as Intrabond Liquid Turquoise GLL (Direct Blue 86, Cromp- sodium phosphate; morpholinosulfonic acids such as 4- ton and Knowles), Cibracron Brilliant Red 38- A (Reactive morpholinoethane sulfonic acid and 4-morpholinepro- Red 4, Aldrich Chemical), Drimarene Brilliant Red X- 2B panesulfonic acid; and other basic or acidic components (Reactive Red 56, Pylam, Inc.), Levafix Brilliant Red E- which do not interfere with the jetability of the ink- jet ink. 4B (Mobay Chemical), Levafix Brilliant Red6BA E- 20 If used, buffering agents typically comprise less than 10% (Mobay Chemical), Pylam Certified D&C Red #28 (Acid by weight of the ink-jet ink composition. Red 92, Pylam), Direct Brill Pink B Ground Crude [0036] As noted above, ink-jet inks are solvent based (Crompton & Knowles), Cartasol Yellow GTF Presscake inks wherein the colorants are chosen and specifically (Sandoz, Inc.), Tartrazine Extra Conc. (FD&C Yellow #5, designed to be soluble or dispersed in common solvents Acid Yellow 23, Sandoz, Inc.), Catodirect Yellow RL (Di- 25 such as water and alcohols. Therefore, application of a rect Yellow 86, Carolina Color and Chemical), Cartasol highlighter ink containing similar solvents can cause the Yellow GTF Liquid Special 110 (Sandoz, Inc.), D&C Yel- ink-jet colorants to dissolve or disperse into the highlight- low #10 (Yellow 3, Tricon), Yellow Shade 16948 (Tricon), er ink composition as it is applied to the surface. The Basacid Black X34 (BASF), Carta Black 2GT (Sandoz, diffusion of components in the solvent and the physical Inc.), Neozapon Red 492 (BASF), Orasol Red G (Ciba- 30 motion of the highlighter marker can carry the ink- jet col- Geigy), Direct Brilliant Pink B (Crompton-Knolls), Aizen orants away from their initially printed positions. As a re- Spilon Red C-BH (Hodagaya Chemical Company), Kay- sult, the printed image often loses edge acuity and color- anol Red 3BL (Nippon Kayaku Company), Levanol Bril- ed streaks can occur. liant Red 3BW (Mobay Chemical Company), Levaderm [0037] Furthermore, many ink-jet pigments are dis- Lemon Yellow (Mobay Chemical Company), Aizen Spi- 35 persed using carboxylic-acid functional groups. Such lon Yellow C-GNH (Hodagaya Chemical Company), functionalized ink-jet pigments can be formed either by Spirit Fast Yellow 3G, Sirius Supra Yellow GD 167, Car- covalently attaching acid containing moieties to the pig- tasol Brilliant Yellow 4GF (Sandoz), Pergasol Yellow ments (as in CABOJET 300, available from Cabot Cor- CGP (Ciba-Geigy), Orasol Black RL (Ciba-Geigy), Ora- poration) or by non- covalently adsorbing acid- containing sol Black RLP (Ciba-Geigy), Savinyl Black RLS (San- 40 polymers onto the pigments. These functional groups doz), Dermacarbon2GT (Sandoz). PyrazofBlack BG (ICl have an advantage that under acidic conditions (pH<7), Americas), Morfast Black Conc A (Morton-Thiokol), Dia- the functional groups are protonated, lose their charge, zolBlack RN Quad (ICI Americas), Orasol BlueGN (Ciba- and hence can cause the pigment to coagulate or crash. Geigy), Savinyl Blue GLS (Sandoz, Inc.), Luxol Blue MB- This advantage allows pigments to be crashed on the SN (Morton-Thiokol), Sevron Blue 5GMF (ICI Americas), 45 paper surface, allowing for improved optical density, and Basacid Blue 750 (BASF); Levafix dyes available edge acuity, and bleed resistance. By using the highlight- from Bayer; Procion dyes (available from ICI Americas; er inks in accordance with embodiments of the present Cibacron Red F-B, Cibacron Black BG, Lanasol Black B, invention, the acid buffer can be specifically tailored to Lanasol Red 5B. Lanasol Red B, and Lanasol Yellow 46, prevent the ink-jet colorants from dissolving or otherwise all available from Ciba-Geigy; Baslien dyes available 50 becoming dislodged from their initially printed positions. from BASF; Sumifix dyes available from Sumitomo In particular, the present invention would be useful when Chemical Company; Intracron dyes available from used with such functionalized pigments as described Crompton and Knowles, Dyes and Chemicals Division; above. mixtures thereof, and the like. [0038] Thus, while the present invention has been de- [0034] Although the above lists of colored pigments 55 scribed above with particularity, the following examples and dyes are provided, they are in no way intended to provide further detail in connection with what is presently be limiting of the present invention and it will be under- deemed to be practical embodiments of the invention. stoodthat otherknown pigmentsand/or dyes canbe used

5 9 EP 1 987 107 B1 10

EXAMPLES Yellow 23 dye, and balance water. Furthermore, the ink- jet image generated contained narrow lines, with thick- Example 1 ness equivalent to that of 10 point type (rather than the 2 mm thick printed bars of examples 1-4, which typically [0039] A highlighter ink composition was prepared by 5 results in greater smearing due to greater amounts of forming a solution having 16 wt% glycerol, 2 wt% Basic continuous ink). The results indicated 100% acceptable Yellow 40, and balance water. The highlighter ink com- for one pass and 25% for two passes. position was placed into an empty AVERY EVERBOLD highlighter marker. Images were printed on a several Example 6 commercially available papers, i.e. Hewlett-Packard 10 Bright White, Hammermill Color Copy, Hewlett-Packard [0045] The same procedure was followed as in Exam- Multipurpose, GREAT WHITE Ink-jet (available from In- ple 5, except the highlighter ink was prepared by forming ternational Paper Co.), and Multicopy Original (available a solution having 16 wt% dipropylene glycol, 2 wt% Acid from Stora Enso). The images were printed using black Yellow 23 dye, 3 wt% succinic acid, and balance water. ink-jet ink from an HP 5550 ink jet printer to form a series 15 The results indicated 100% acceptable for one pass and of 2 mm wide bars having an optical density of 1.40. The 100% for two passes. images were then highlighted using the highlighter ink composition using a mechanism that applies a downward force of 300 grams. Claims [0040] Smear was measured using a visual scale20 based on the percentage of print samples averaged over 1. A highlighter ink composition, comprising: the five substrates that appear dear with minimal smear- ing after one and two passes of the highlighter marker. a. an acid buffer having a pKa from 2 to 6; The results indicated 0% acceptable for both one and b. a highlighter colorant selected from the group two passes. 25 consisting of Basic Yellow 40, Acid Yellow 23, Acid Red 52, Acid Blue 9, and mixtures thereof; Example 2 and c. a liquid vehicle. [0041] The same procedure was followed as in Exam- ple 1, except the highlighter ink was prepared by forming 30 2. The composition of claim 1, wherein said acid buffer a solution having 16 wt% glycerol, 2 wt% Basic Yellow is selected from the group consisting of succinic acid, 40, 3 wt% succinic acid, and balance water. The results citric acid, glutaric acid, acetic acid, beta- alanine, indicated 60% acceptable for one pass and 0% for two aspartic acid, ascorbic acid, and mixtures thereof. passes of the highlighter marker. 35 3. The composition of claim 1, wherein said acid buffer Example 3 has a pKa from 4 to 6.

[0042] The same procedure was followed as in Exam- 4. The composition of claim 1, wherein said acid buffer ple 1, except the highlighter ink was prepared by forming comprises from 0.5 wt% to 10 wt% of the composi- a solution having 16 wt% glycerol, 2 wt% Basic Yellow 40 tion. 40, 6 wt% succinic acid, and balance water. The results indicated 60% acceptable for one pass and 0% for two 5. The composition of claim 4, wherein said acid buffer passes of the highlighter marker. comprises from 2 wt% to 3 wt% of the composition.

Example 4 45 6. The composition of claim 1, wherein said highlighter colorant is a fluorescent colorant. [0043] The same procedure was followed as in Exam- ple 1, except the highlighter ink was prepared by forming 7. A methodof reducing print smearduring highlighting, a solution having 16 wt% glycerol, 2 wt% Basic Yellow comprising the steps of: 40, 3 wt% citric acid, and balance water. The results in- 50 dicated 40% acceptable for one pass and 0% for two a. ink-jet printing an ink-jet ink to form an image passes of the highlighter marker. on a substrate; b. applying a highlighter composition to the im- Example 5 age, said highlighter composition including an 55 acid buffer having a pKa from 2 to 6, a highlighter [0044] A similar procedure was followed as in Example colorant selected from the group consisting of 1, except the highlighter ink was prepared by forming a Basic Yellow 40, Acid Yellow 23, Acid Red 52, solution having 16 wt% dipropylene glycol, 2 wt% Acid Acid Blue 9, and mixtures thereof, and a liquid

6 11 EP 1 987 107 B1 12

vehicle. ist.

8. The method of claim 8, wherein said acid buffer is 7. Verfahren zum Verringern des Verwischens beim selected from the group consisting of succinic acid, Druck während des Markierens, wobei das Verfah- citric acid, glutaric acid, acetic acid, beta- alanine, 5 ren die folgenden Schritte umfasst: aspartic acid, ascorbic acid, and mixtures thereof. a. Tintenstrahldrucken einer Tintenstrahltinte, 9. A smear resistant highlighter system, comprising: um ein Bild auf einem Substrat zu bilden; b.Auftragen einerMarkierzusammensetzungen a. an ink-jet ink printed on a substrate, said ink- 10 auf das Bild, wobei die Markierzusammenset- jet ink comprising an ink-jet colorant ; and zung einen Säurepuffer mit einem pKa von 2 bis b. a highlighter composition comprising an acid 6, ein Markierfärbemittel, ausgewählt aus der buffer having a pKa from 2 to 6, a highlighter Gruppe bestehend aus Basic Yellow 40, Acid colorant selected from the group consisting of Yellow 23, Acid Red 52, Acid Blue 9 und Mi- Basic Yellow 40, Acid Yellow 23, Acid Red 52, 15 schungen davon, sowie ein flüssiges Vehikel Acid Blue 9, and mixtures thereof, and a liquid umfasst. vehicle, wherein said acid buffer is configured for reducing mobility of the ink-jet colorant. 8. Verfahren nach Anspruch 8, wobei der Säurepuffer aus der Gruppe bestehend aus Bernsteinsäure, Zi- 10. The system of claim 9, wherein said acid buffer is 20 tronensäure, Glutarsäure, Essigsäure, Beta-Alanin, selected from the group consisting of succinic acid, Asparaginsäure, Ascorbinsäure und Mischungen citric acid, glutaric acid, acetic acid, beta- alanine, davon ausgewählt ist. aspartic acid, ascorbic acid, and mixtures thereof. 9. Wischfestes Markiersystem, umfassend: 11. The system of claim 9, wherein said acid buffer com- 25 prises from 0.5 wt% to 10 wt% of the composition. a. eine Tintenstrahltinte, die auf ein Substrat ge- druckt ist, wobei die Tintenstrahltinte ein Tinten- strahlfärbemittel umfasst; und Patentansprüche b. eine Markierzusammensetzung, die einen 30 Säurepuffer mit einem pKa von 2 bis 6, ein Mar- 1. Markiertintenzusammensetzung, umfassend: kierfärbemittel, ausgewählt aus der Gruppe be- stehend aus Basic Yellow 40, Acid Yellow 23, a. einen Säurepuffer mit einem pKa von 2 bis 6; Acid Red 52, Acid Blue 9 und Mischungen da- b. ein Markierfärbemittel, ausgewählt aus der von, und ein flüssiges Vehikel umfasst, wobei Gruppe bestehend aus Basic Yellow 40, Acid 35 der Säurepuffer eingerichtet ist, um die Mobilität Yellow 23, Acid Red 52, Acid Blue 9 und Mi- des Tintenstrahlfärbemittels zu verringern. schungen davon; und c. ein flüssiges Vehikel. 10. System nach Anspruch 9, wobei der Säurepuffer aus der Gruppe bestehend aus Bernsteinsäure, Zitro- 2. Zusammensetzung nach Anspruch 1, wobei der40 nensäure, Glutarsäure, Essigsäure, Beta-Alanin, Säurepuffer aus der Gruppe bestehend aus Bern- Asparaginsäure, Ascorbinsäure und Mischungen steinsäure, Zitronensäure, Glutarsäure, Essigsäure, davon ausgewählt ist. Beta-Alanin, Asparaginsäure, Ascorbinsäure und Mischungen davon ausgewählt ist. 11. System nach Anspruch 9, wobei der Säurepuffer 0,5 45 Gew.-% bis 10 Gew.- % der Zusammensetzung um- 3. Zusammensetzung nach Anspruch 1, wobei der fasst. Säurepuffer einen kPa von 4 bis 6 aufweist.

4. Zusammensetzung nach Anspruch 1, wobei der Revendications Säurepuffer 0,5 Gew.- % bis 10 Gew.- % der Zusam- 50 mensetzung umfasst. 1. Composition d’encre de surlignage comprenant :

5. Zusammensetzung nach Anspruch 4, wobei der a. un tampon acide ayant un pKa de 2 à 6 ; Säurepuffer2 Gew.- %bis 3Gew.- % der Zusammen- b. un colorant de surlignage choisi dans le grou- setzung umfasst. 55 peconsistant en Jaune Basique 40,Jaune Acide 23, Rouge Acide 52, Bleu Acide 9 et leurs 6. Zusammensetzung nach Anspruch 1, wobei das mélanges ; et Markierfärbemittel ein fluoreszierendes Färbemittel c. un véhicule liquide.

7 13 EP 1 987 107 B1 14

2. Composition selon la revendication 1, dans laquelle en l’acide succinique, l’acide citrique, l’acide gluta- ledit tampon acide est choisi dans le groupe consis- rique, l’acide acétique, la bêta-alanine, l’acide as- tant en l’acide succinique, l’acide citrique, l’acide glu- partique, l’acide ascorbique et leurs mélanges. tarique, l’acide acétique, la bêta- alanine, l’acide as- partique, l’acide ascorbique et leurs mélanges. 5 11. Système selon la revendication 9, dans lequel ledit tampon acide comprend de 0,5 % en poids à 10 % 3. Composition selon la revendication 1, dans laquelle en poids de la composition. ledit tampon acide a un pKa de 4 à 6.

4. Composition selon la revendication 1, dans laquelle 10 ledit tampon acide comprend de 0,5 % en poids à 10 % en poids de la composition.

5. Composition selon la revendication 4, dans laquelle ledit tampon acide comprend de 2 % en poids à 3 % 15 en poids de la composition.

6. Composition selon la revendication 1, dans laquelle ledit colorant de surlignage est un colorant fluores- cent. 20

7. Procédé de réduction d’une bavure d’impression pendant le surlignage, comprenant les étapes con- sistant à : 25 a. imprimer au jet d’encre une encre à jet d’encre pour former une image sur un substrat ; b. appliquer une composition de surlignage à l’image, ladite composition de surlignage com- prenant un tampon acide ayant un pKa de 2 à 30 6, un colorant de surlignage choisi dans le grou- pe consistant en Jaune Basique 40, Jaune Acide 23, Rouge Acide 52, Bleu Acide 9 et leurs mélanges ; et un véhicule liquide. 35 8. Procédé selon la revendication 8, dans lequel ledit tampon acide est choisi dans le groupe consistant en l’acide succinique, l’acide citrique, l’acide gluta- rique, l’acide acétique, la bêta-alanine, l’acide as- partique, l’acide ascorbique et leurs mélanges. 40

9. Système de surlignage résistant à la bavure, comprenant :

a. une encre à jet d’encre imprimée sur un subs- 45 trat, ladite encre à jet d’encre comprenant un colorant à jet d’encre ; et b. une composition de surlignage comprenant un tampon acide ayant un pKa de 2 à 6, un co- lorant de surlignage choisi dans le groupe con- 50 sistant en Jaune Basique 40, Jaune Acide 23, RougeAcide 52,Bleu Acide 9 etleurs mélanges , et un véhicule liquide, ledit tampon acide étant configuré pour réduire la mobilité du colorant à jet d’encre. 55

10. Système selon la revendication 9, dans lequel ledit tampon acide est choisi dans le groupe consistant

8 EP 1 987 107 B1

REFERENCES CITED IN THE DESCRIPTION

This list of references cited by the applicant is for the reader’s convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

Patent documents cited in the description

• WO 0206103 A [0004]

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