# Patent

## Title
Highlightable marking composition, method of highlighting the same, highlightable marking composition kit, and highlighted marking composition complex

## Abstract

A highlightable ink including a colored pigment and an eradicable colorant; a kit including the highlightable ink and an eradicator solution; an ink complex including a colorless or substantially colorless eradicable dye selected from the group consisting of diarylmethane derivatives, triarylmethane derivatives, and methine dyes, and a colored pigment; and methods of applying an eradicator to at least a portion of a marking made with a highlightable ink, are disclosed herein.

## Background
BACKGROUND
1. Technical Field
The invention relates generally to color changing inks.
2. Brief Description of Related Technology
Eradicable ink systems generally include two components. One component is an aqueous ink that includes a dye—typically a triarylmethane—that can be rendered substantially colorless when contacted with a substance such as a sulfite reducing agent or an amine. The second component is an aqueous eradicator fluid that includes a substance that can cause a complementary dye to convert to a substantially colorless form. A user writes with the ink and, if correction is necessary, applies the eradicator fluid to the ink marking to decolorize the dye.
Highlighting a marking is typically performed using a fluorescent ink applied over a regular marking made by an ink on a substrate (e.g., paper). A typical fluorescent highlighting ink has a translucent quality to allow for a user to apply the highlight ink and yet still see the regular ink marking under the fluorescent ink marking made by the marker. While this process serves to highlight a regular ink marking, it also has the undesirable effect of highlighting areas of the substrate that do not include a regular ink marking.



BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a theoretical mechanism for the conversion of Acid Violet 17 from a violet colored compound to a substantially colorless (eradicated) compound.



SUMMARY
One aspect of the invention is an ink including a pigment and an eradicable colorant.
Another aspect of the invention is a method of highlighting an ink, the method including the steps of applying a highlightable ink to a make a marking on a substrate and then applying an eradicator solution to at least a portion of that marking.
Yet another aspect of the invention is a kit including a highlightable ink and an eradicator.
Yet another aspect of the invention is an ink complex, including an at least substantially colorless dye selected from the group consisting of diarylmethane derivatives, triarylmethane derivatives, methine dyes, and combinations thereof, and a colored pigment.
Further aspects and advantages of the invention will be apparent to those skilled in the art from a review of the following detailed description, taken in conjunction with the appended claims. While the ink, method of using the ink, the kit, and the complex are susceptible of embodiments in various forms, the description hereinafter includes specific embodiments of the invention with the understanding that the disclosure is illustrative, and is not intended to limit the inventions to the specific embodiments described herein.
DETAILED DESCRIPTION
The process of ink marking and eradication proceeds in two steps: the first is the marking of a substrate (e.g., paper) with an eradicable ink, and the second is the application of an eradication solution to the marking. A typical formulation for an eradicable ink includes a solvent (e.g., water) to dissolve a dye that is capable of being eradicated (e.g., a triarylmethane dye). The eradication solution includes an eradicator that, by a chemical process, converts a complementary colored dye into a substantially colorless compound or a color that matches that of the substrate (e.g., white for white paper). Such compounds include oxidizing agents, reducing agents, acid-base reactants, and chemicals that can sublime under the influence of heat. Without intending to be limited to any particular method of eradication, it is believed that for triarylmethane dyes, for example, the active colored dye is able to reflect color in the visible range (between 380 nm to 780 nm) because of the conjugation of the aromatic rings in the molecule; however, once a reducing agent (e.g., sodium sulfite) is applied to the triarylmethane dye, it destroys the conjugation by converting the sp2 carbon center (shown in FIG. 1 with a *) to an sp3 carbon by oxidizing that carbon center. Once this change in the hybridization takes place, the conjugation between the various rings of the dye is lost and the dye becomes at least substantially colorless. This proposed process is shown in FIG. 1 for Acid Violet 17.
The eradication solution preferably includes water or an organic solvent as the primary solvent, an eradicator such as, a sulfite (e.g., sodium sulfite), bisulfite, or an amine (e.g., sodium glycinate) that can cause susceptible dyes to lose their colors (e.g., triarylmethane dyes) or to change color, and a film-forming polymer. A suitable eradicator solution for the inks disclosed herein is a commercially available eradicator solution that includes both a sulfite and an amine as active eradicating agents (available from Sanford Reynolds of Valence, France). Preferably, the eradicator is a compound selected from the group consisting of a sulfite reducing agent (e.g., sodium sulfite), a bisulfite reducing agent (e.g., sodium bisulfite), and combinations thereof.
The highlightable nature of the ink is derived from the ability to convert the dye (chromophore) from a colored compound to at least substantially colorless, while not affecting the substantially insoluble, colored pigment. As discussed above, this can be achieved with the combination of a colored pigment and a dye that is sensitive to an eradicator (i.e., an oxidizing agent, a reducing agent, an acid, a base, heat, etc.). Dyes which are capable of becoming at least substantially colorless upon the application of an eradicator include diarylmethane derivative dyes, triarylmethane derivative dyes, and methine derivative dyes. Diaryl dyes suitable for use with the inks disclosed herein include Auramine O (Chemical Index No. 41000), and Basic Yellow 2 (Chemical Index No. 41000). In the colored state, the bi- and triarylmethane, and methine dyes often contain one or more cationic imine groups. The generic structure of a triarylmethane dye is shown below in formula (II):




wherein each R group is the same or different and preferably is selected from C1 to C10 alkyl groups. A non-exhaustive list of triarylmethane dyes for use in inks disclosed herein are listed below in Table I.










TABLE I1





Color Index Name
Color Index No.
Common/Commercial Name

















Acid Blue 22
42755
Water Blue I


Acid Blue 93
42780
Methyl Blue


Acid Fuchsin
42685
Acid Fuchsin


Acid Green
42095
Light Green Sf Yellowish


Acid Green 5
42095
Light Green Sf Yellowish


Acid Magenta
42685
Acid Fuchsin


Acid Roseine
42685
Acid Fuchsin


Acid Rubin
42685
Acid Fuchsin


Acid Violet 17
42650
Acid Violet 4BN


Acid Violet 19
42685
Acid Fuchsin


Alizarol Cyanin R
43820
Eriochrome Cyanin R




Triphenylmethane Chrome


Aluminon
43810
Violet Cg


Aniline Blue Ws

Aniline Blue Ws


Basic Blue 8
42563
Victoria Blue 4r


Basic Blue 15
44085
Night Blue


Basic Blue 20
42585
Methyl Green


Basic Blue 26
44045
Victoria Blue B


Basic Fuchsin

Basic Fuchsin


Basic Green 4
42000
Malachite Green


Basic Red 9
42500
Pararosanilin


Basic Red 14
48016
Cationic Brilliant Red 5GN


Basic Violet 2
42520
New Fuchsin


Basic Violet 3
42555
Crystal Violet


Basic Violet 4
42600
Ethyl Violet


Basic Violet 14
42510
Rosanilin




Triphenylmethane Chrome


Chrome Violet Cg
43810
Violet Cg


Chromoxane Cyanin R
4382
Eriochrome Cyanin R


Cotton Blue
42780
Methyl Blue


Crystal Violet
42555
Crystal Violet


Dahlia
42530
Hoffman's Violet


Diamond Green B
42000
Malachite Green


Eriochrome Cyanin R
43820
Eriochrome Cyanin R


Ethyl Green
42590
Ethyl Green


Ethyl Violet
42600
Ethyl Violet


Fast Green Fcf
42053
Fast Green Fcf


Food 3
42053
Fast Green Fcf


Gentian Violet

Methyl Violet 2b


Helvetia Blue
42780
Methyl Blue


Hoffman's Violet
42530
Hoffman's Violet


Light Green
42095
Light Green Sf Yellowish


Lissamine Green Sf
42095
Light Green Sf Yellowish


Magenta 0
42500
Pararosanilin


Magenta I
42510
Rosanilin


Magenta II

Magenta II


Magenta III
42520
New Fuchsin


Malachite Green
42000
Malachite Green


Methyl Blue
42780
Methyl Blue


Methyl Green
42585
Methyl Green


Methyl Violet
42535
Methyl Violet 2b


Methyl Violet 2b
42535
Methyl Violet 2b


Methyl Violet 10b
42555
Crystal Violet


Mordant Blue 3
43820
Eriochrome Cyanin R




Triphenylmethane Chrome


Mordant Violet 39
43810
Violet Cg


New Fuchsin
4252
New Fuchsin


Night Blue
44085
Night Blue


Pararosanilin
42500
Pararosanilin


Primula
42530
Hoffman's Violet


Rosanilin
42510
Rosanilin


Solochrome Cyanin R
43820
Eriochrome Cyanin R


Victoria Blue 4r
42563
Victoria Blue 4r


Victoria Blue B
44045
Victoria Blue B


Victoria Green B
42000
Malachite Green


Water Blue I
42755
Water Blue I





1See, R. D. Lillie, Conn's Biological Stains (8th ed., 1969), Williams and Wilkins Company, Baltimore, Maryland; Susan Budavari (Ed.), The Merck Index, (12th ed., 1996), Merck & Co., Whitehouse Station, N.J; see also, P. A. Lewis (Ed.), Pigment Handbook Vol. I, Properties and Economics, sections I(D)f(1) and I(D)g, John Wiley & Sons, (2nd ed., 1988); H. Zollinger, Color Chemistry: Syntheses, Properties, and Applications of Organic Dyes And Pigments, Chapter 4, VCH Publishers (1987); D. R. Waring and G. Hallas (Eds.), The Chemistry and Application of Dyes, Chapter 2, Section IX, Plenum Press (1990); and M. Okawara, T. Kitao, T. Hirashima, and M. Matsuoka, Organic Colorants: A Handbook of Data of Selected Dyes for Electro-Optical Applications, Section VI, Elsevier (1988).






Another type of dye that can be used in an ink are the methine class of dyes. The methine dyes generally contain one or more methine group chromophores (—CH═), also called methylidyne or methine group. When the methine dye only contains one methine group the dye is sometimes referred to as a cyanine dye, with three methine groups the dye is sometime referred to as a carbocyanine dye, and with more than three methine groups the dye is often referred to as a polymethine dye. An example of a methine dye is Thiazole Orange:




wherein the bonds that make up the methine group are shown above as broken lines. Other examples of methine dyes include Basic Red 15, Basic Yellow 11, and Basic Yellow 13. For a comprehensive listing of methine dyes, see F. M. Hamer, The Chemistry of Heterocyclic Compounds, A. Weissberger (Ed.), The Cyanine Dyes and Related Compounds, Wiley Interscience, New York (1964).

When formulating a highlightable ink of a particular color, whether by the addition of one eradicable dye or a mixture of eradicable dyes and a pigment, the rate of eradication of a dye (once applied to a substrate) is a consideration when selecting an eradicable dye. Without intending to be limited to a particular mechanism, it is believed that the rate of eradication of diarylmethane, triarylmethane, and methine dyes is proportional to the concentration of the dye in the ink. The highlightable ink described herein includes one or more eradicable dyes selected from the group consisting of diarylmethane dyes, triarylmethane dye, methine dyes, and combinations thereof. The dye preferably is present in an amount in a range of about 0.01% to about 10% by weight of the total weight of the composition, more preferably about 0.1% to about 6% by weight.
In selecting particular dyes and colored pigments for use in the ink, there are a number of dyes and pigments to choose from and, as a result, dyes and pigments of different colors can be mixed to create an ink of almost any color. A highlightable ink disclosed herein can include one or more dyes and one or more pigments that, when combined, provide an ink from of a variety of colors. Preferably, the dye and pigment are combined to provide an ink that is green in color in the non-eradicated state and is red in color in the eradicated (highlighted) state. There are at least two competing considerations when formulating an ink that includes at least one eradicable dye—the rate of eradication and the intensity of the color. An increase in the concentration of the eradicable dye used to create the green color will increase the intensity of the color, however, as discussed above, an increase in the dye concentration also increases the amount of time needed to eradicate the dye. It has been found that for the ink disclosed herein a dye concentration in the range of about 0.1% to about 6% by weight based on the total weight of the composition is a preferred concentration to balance these considerations.
The use of a substantially non-soluble pigment in combination with an eradicable dye prevents smearing of the ink upon eradication. Without intending to be limited to a particular mechanism for smear reduction, it is believed that when the substantially insoluble pigment is applied to a porous substrate such as paper, the pigment is not re-dissolved by the aqueous eradicator and is further prevented from smearing by being disposed in the pores of the substrate and thereby less influenced by the eradicator solution. Alternatively, the same effect can be achieved with the use of a binder that binds a colorant (e.g., a pigment) to the substrate and, thereby, allows the colorant to be less influenced by the eradication solution. A preferred ink includes one or more colored pigments, and one or more eradicable dyes.
The process of highlighting with an ink begins with the eradication of the eradicable dye(s) in the ink mixture with an eradicator. The colored pigment, however, is substantially unaffected by the eradicator and continues to contribute to the color of the ink. A highlightable ink disclosed herein will have two different colored states. The first state can be described as the non-eradicated state, wherein the ink (or at least a portion of a marking made with the ink) has not come in contact with an eradicator. A second state of color can be described as the eradicated (highlighted) state, wherein the ink (or at least a portion of a marking made with the ink) has come in contact with the an eradicator and the ink has made a change in color, preferably sufficient to be perceptible to the human eye. Once the dye is eradicated (the ink is in the eradicated state), the color of the ink preferably is primarily determined by the color contributed by the colored pigments in the ink mixture. It is preferred that the color contributed by the color pigments is different from the color of the ink in its non-eradicated state, to achieve a drastic highlighting effect. Preferably, the color of the ink in its non-eradicated state is dark green, and the color of the ink in the eradicated state is red.
Pigments used in the ink disclosed herein cover a wide variety of colors and types, including organic, inorganic, natural, and synthetic pigments. Pigments are substantially insoluble in an aqueous medium and are particulate material that is dispersed in the ink solution. Typically, pigments are chemically inert, non-toxic, and stable to heat and light. A non-exhaustive list of pigment for use in inks disclosed herein are listed below in Table II.









TABLE II





Pigment Common/

Color Index


Commercial Name
Manufacturer
Hue







Permanent Yellow DHG
Hoechst
Yellow 12



(Frankfurt, Germany)


Permanent Yellow GR
Hoechst
Yellow 13



(Frankfurt, Germany)


Permanent Yellow G
Hoechst
Yellow 14



(Frankfurt, Germany)


Permanent Yellow NCG-71
Hoechst
Yellow 16



(Frankfurt, Germany)


Permanent Yellow GG
Hoechst
Yellow 17



(Frankfurt, Germany)


Hansa Yellow RA
Hoechst
Yellow 73



(Frankfurt, Germany)


Hansa Brilliant Yellow
Hoechst
Yellow 74


5GX-02
(Frankfurt, Germany)


DALAMAR Yellow
Heubach
Yellow 74


YT-858-D
(Langelsheim, Germany)


Hansa Yellow X
Hoechst
Yellow 75



(Frankfurt, Germany)


NOVOPERM Yellow HR
Hoechst
Yellow 83



(Frankfurt, Germany)


CHROMOPHTAL Yellow
Ciba-Geigy
Yellow 93


3G
(Basle, Switzerland)


CHROMOPHTAL Yellow
Ciba-Geigy
Yellow 95


GR
(Basle, Switzerland)


NOVOPERM Yellow FGL
Hoechst
Yellow 97



(Frankfurt, Germany)


Hansa Brilliant Yellow
Hoechst
Yellow 98


10GX
(Frankfurt, Germany)


Permanent Yellow G3R-01
Hoechst
Yellow 114



(Frankfurt, Germany)


CHROMOPHTAL Yellow
Ciba-Geigy
Yellow 128


8G
(Basle, Switzerland)


IRGAZIN Yellow 5GT
Ciba-Geigy
Yellow 129



(Basle, Switzerland)


HOSTAPERM Yellow
Hoechst
Yellow 151


H4G
(Frankfurt, Germany)


HOSTAPERM Yellow
Hoechst
Yellow 154


H3G
(Frankfurt, Germany)


L74-1357 Yellow
Sun Chemical



(Cincinnati, Ohio)


L75-1331 Yellow
Sun Chemical



(Cincinnati, Ohio)


L75-2377 Yellow
Sun Chemical



(Cincinnati, Ohio)


HOSTAPERM Orange GR
Hoechst
Orange 43



(Frankfurt, Germany)


PALIOGEN Orange
BASF
Orange 51



(Mount Olive, New Jersey)


IRGALITE Rubine 4BL
Ciba-Geigy
Red 57:1



(Basle, Switzerland)


QUINDO Magenta
Mobay Chemical
Red 122



(Haledon, New Jersey)


INDOFAST Brilliant
Mobay Chemical
Red 123


Scarlet
(Haledon, New Jersey)


HOSTAPERM Scarlet GO
Hoechst
Red 168



(Frankfurt, Germany)


Permanent Rubine F6B
Hoechst
Red 184



(Frankfurt, Germany)


MONASTRAL Magenta
Ciba-Geigy
Red 202



(Basle, Switzerland)


MONASTRAL Scarlet
Ciba-Geigy
Red 207



(Basle, Switzerland)


HELIOGEN Blue L 6901F
BASF
Blue 15:2



(Mount Olive, New Jersey)


HELIOGEN Blue NBD
BASF


7010
(Mount Olive, New Jersey)


HELIOGEN Blue K 7090
BASF
Blue 15:3



(Mount Olive, New Jersey)


HELIOGEN Blue L 7101F
BASF
Blue 15:4



(Mount Olive, New Jersey)


PALIOGEN Blue L 6470
BASF
Blue 60



(Mount Olive, New Jersey)


HEUCOPHTHAL Blue G,
Heubach
Blue 15:3


XBT-583D
(Langelsheim, Germany)


HELIOGEN Green K 8683
BASF
Green 7



(Mount Olive, New Jersey)


HELIOGEN Green L 9140
BASF
Green 36



(Mount Olive, New Jersey)


MONASTRAL Violet R
Ciba-Geigy
Violet 19



(Basle, Switzerland)


MONASTRAL Red B
Ciba-Geigy
Violet 19



(Basle, Switzerland)


QUINDO Red R6700
Mobay Chemical



(Haledon, New Jersey)


QUINDO Red R6713
Mobay Chemical



(Haledon, New Jersey)


INDOFAST Violet
Mobay Chemical
Violet 23



(Haledon, New Jersey)


MONASTRAL Violet
Ciba-Geigy
Violet 42


Maroon B
(Basle, Switzerland)


RAVEN 1170
Columbian Chemicals
Black 7



(Marietta, Georgia)


Special Black 4A
Degussa
Black 7



(Parsippany, New Jersey)


STERLING NS Black
Eastech Chemical, Inc.
Black 7



(Philadelphia, Pennsylvania)


STERLING NSX 76
Eastech Chemical, Inc.
Black 7



(Philadelphia, Pennsylvania)


TIPURE R-101
Du Pont,



(Wilmington, Delaware)


Mogul L
Eastech Chemical, Inc.
Black 7



(Philadelphia, Pennsylvania)









To prepare an ink of a particular color, the amount of colored pigment used in an ink can be balanced with the amount of dye present in the ink to produce the desired color of the ink in its non-eradicated state. Also, when a large amount of colored pigment is used, depending on the substrate, the pigment may over saturate the substrate once the solvent (e.g., water) has evaporated. If over-saturation occurs, the application of the eradicator fluid to the marking can cause smearing of the pigment on the surface of the substrate. Thus, the ink should contain an effective amount to prevent smearing upon application of the eradicator solution, when the smearing effect is not desired. The colored pigment preferably is present in an amount in a range of about 0.01% to about 50% by weight of the total weight of the composition, more preferably about 0.1% to about 20% by weight.
The color of the ink will primarily be determined by the combination of an eradicable dye and a colored pigment which causes the inks to reflect a particular wavelength of visible light. Mixing a dye and pigment to form an ink of a particular color can be done with the use of two complementary colors, or combinations that contain all three primary colors (red, yellow, and blue). When two complementary colors are mixed, the resultant mixture is gray, with black being the completely saturated form of gray. The complement color of red is green, the complement color of orange is blue, and the complement color of yellow is violet. When using complementary colors, these pairs of complementary colors actually reflect all three primary colors. For example, when red and green dyes are mixed as complementary colors, it is the equivalent of mixing red with yellow and blue, because green is composed of a mixture of the two primary colors yellow and blue. In another example, the mixture of the two complementary colors yellow and violet is the equivalent of mixing yellow with red and blue, because violet is composed of two primary colors, red and blue.
An ink disclosed herein can optionally include a binder resin to impart smear and water resistance to the ink. Binder resins for use in the ink include glycols such as polyethylene glycol, polyvinylpyrrolidone, copolymers and salts thereof, polyvinylacetate, copolymers and salts thereof, and polyacrylic acids, copolymers and salts thereof, other film-forming water-soluble resins, and combinations thereof. The binder resin preferably is selected from PVP and copolymers thereof, PVA and copolymers thereof, and combinations of the foregoing. More preferably, the binder resin is selected from PVP, copolymers thereof, and combinations of the foregoing.
The binder resin can also be used to control the viscosity of the ink. When a highly viscous ink is desired (e.g., cP>10,000), the use of a larger amount a binder resin will achieve a highly viscous ink. When the binder resin used is a polymer (e.g., PVP), the resin can be selected with a wide range of viscosities and molecular weights. For example, PVP is commercially available at various viscosities, and in a molecular weight range of 10,000 daltons to 1,300,000 daltons (Aldrich Chemical Co., Inc., Milwaukee, Wis.) for example. Thus, depending on the molecular weight of the polymer resin, there can be a great deal of variation in the amount of resin utilized in the ink, and the overall viscosity of the ink. When, for example, a low molecular weight PVP is used, the ink can achieve smear and water resistance while still maintaining a low viscosity (e.g., about 2 cP to about 5 cP). A binder resin used herein preferably is present in an amount in a range of about 1 wt. % to about 80 wt. % based on the total weight of the composition, more preferably about 5 wt. % to about 20 wt. %.
The ink preferably is water-based (aqueous). Water preferably is present in an amount in a range of about 70% to about 95% by weight of the total weight of the composition, more preferably about 80% to about 90% by weight. The water acts to dissolve the dye component and to suspend the colored pigment and also provides an improved washability of the ink from various materials (e.g., clothes) as compared to oil-based inks.
When an aqueous ink is used in a delivery system such as a writing instrument or an ink-jet cartridge, is it preferred to use one or more organic solvents to control the amount of time it takes for the ink to dry once it is applied to a substrate (drying time). Preferred delivery systems include a writing instrument and an ink-jet cartridge. As compared to water, organic solvents will typically evaporate faster than water, and when an aqueous ink includes an organic solvent, the drying time will decrease. In order to optimize and exercise control over the drying time of an ink, it may be necessary to include more than one organic solvent. An organic solvent preferably is substantially soluble in water. Preferably, the organic solvent is selected from the group consisting of glycols, ureas, fatty alcohols, dimethylformamide, formamide, dimethylsulfoxide, high molecular weight hydrocarbons (i.e., a hydrocarbon with twelve or more carbon atoms), low molecular weight hydrocarbons (i.e., a hydrocarbon with eleven or fewer carbon atoms), and combinations thereof. More preferably, the organic solvent is polyethylene glycol. The organic solvent, when used, preferably is present in the ink in a range of about 5% to about 30% by weight based on the total weight of the composition, more preferably about 10% to about 20% by weight, to achieve a drying time suitable for typical writing instruments and marking applications.
Glycols for use as an organic solvent, include, but are not limited to, three broad categories of glycols: (a) glycol ethers (e.g., ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monophenyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monoisopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monophenyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, propylene glycol monomethyl ether); (b) glycol ether acetates such as ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate (e.g., ethylene glycol monobutyl ether acetate, ethylene glycol monophenyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, diethylene glycol monophenyl ether acetate, diethylene glycol monoisopropyl ether acetate, ethylene glycol dimethyl ether acetate, ethylene glycol diethyl ether acetate, diethylene glycol dimethyl ether acetate, propylene glycol monomethyl ether acetate, and the like); and (c) glycol acetates (e.g., ethylene glycol monoacetate, ethylene glycol diacetate, and diethylene glycol diacetate). The ink can include other glycols not within one of these three categories, including glycols such as ethylene glycol, and ethoxylated glycols. A glycol can be used in the ink composition, preferably in an amount in the range of about 10% to about 20% by weight based on the total weight of the composition.
Fatty alcohols for use as an organic solvent include, but are not limited to, alcohols having eight through twenty carbon atoms, and fatty alcohols that are ethoxylated with one to three molar equivalents of ethylene oxide. Examples of fatty alcohols and ethoxylated fatty alcohols include, but are not limited to, behenyl alcohol, caprylic alcohol, cetyl alcohol, cetaryl alcohol, decyl alcohol, lauryl alcohol, isocetyl alcohol, myristyl alcohol, oleyl alcohol, stearyl alcohol, tallow alcohol, steareth-2, ceteth-1, cetearth-3, and laureth-2. Additional suitable fatty alcohols are listed in CTFA Cosmetic Ingredient Handbook, First ed., J. Nikotakis (Ed.), The Cosmetic, Toiletry and Fragrance Association, pages 28 and 45 (1988), incorporated herein by reference.
In the ink described herein, the color green can be achieved by the mixing of the combination of dyes and pigments of either two complementary colors (e.g., green-red, or yellow-magenta) or by dyes/pigments with the combination of all three primary colors (red, yellow, and blue). A dark green ink is preferably formed from the combination of a green dye with a pigment selected from the group consisting of a red pigment, a violet pigment, and combinations thereof. A preferred combination is a green dye and red pigment, and the preferred combination is Basic Green 4 and a red pigment or a combination of pigments that combine to form a red pigment dispersion. The preferred red pigment dispersion is LUCONYL 3855 available from BASF of Charlotte, N.C.
When combining two or more colors to form an ink of a desired color, it is understood that the desired color (e.g., green), may be reached even though an undertone of another color (e.g., a redish-black color) might be perceptible. For example, it is understood that an ink that is colored green can have a red or a blue undertone, and yet still be considered a green ink.
It has been found that the combination of a green eradicable dye and a violet and/or a red dye is able to mix to form a green highlightable ink. One embodiment of an ink disclosed herein is a green highlightable ink, including a mixture of one or more of a colored pigment and one or more dyes selected from the group consisting of diarylmethane derivatives, triarylmethane derivatives, methine dyes, and combinations thereof, wherein the mixture of dye and pigment appears green in color.
A green eradicable dye preferably is selected from the group consisting of Acid Green, Acid Green 5, Basic Green 4, Diamond Green B, Ethyl Green, Fast Green Fcf, Food Green 3, Light Green, Lissamine Green Sf, Malachite Green, Methyl Green, Victoria Green B, and combinations thereof, more preferably, the green dye is selected from Basic Green 3, Basic Green 4, and combinations thereof. Preferably, a red dye is selected from the group consisting of Basic Red 9, Basic Red 14, Basic Red 15, Basic Red 29, Basic Red 46, and combinations thereof. Preferably, a violet dye is selected from the group consisting of Acid Violet 17, Acid Violet 19, Basic Violet 2, Basic Violet 3, Basic Violet 4, Basic Violet 14, Chrome Violet Cg, Crystal Violet, Ethyl Violet, Gentian Violet, Hoffman's Violet, Methyl Violet, Methyl Violet 2b, Methyl Violet 10b, Mordant Violet 39, and combinations thereof. To form a yellow ink, a yellow dye is preferably selected from the group consisting of Basic Yellow 11, Basic Yellow 13, Basic Yellow 21, Basic Yellow 28, Basic Yellow 29, Basic Yellow 40, and combinations thereof.
One embodiment of the ink includes an aqueous mixture of a colored pigment, and a dye selected from the group consisting of diarylmethane derivatives, triarylmethane derivatives, methine dyes, and combinations thereof.
Another aspect of the invention is a method of highlighting an ink including the steps of applying a highlightable ink disclosed herein to a substrate to make a mark, and applying an eradicator fluid to at least a portion of the mark. Preferably, the substrate is paper, and preferably the eradicator fluid is selected from the group consisting of a sulfite, a bisulfite, and combinations thereof.
Another aspect of the invention is a kit that includes a highlightable ink described herein together with an eradicator fluid, for use in system of marking a substrate and eradicating the marking. Each of the ink and the eradicator fluid can be disposed in a writing instrument (e.g., a pen) for ease of use or it may be supplied in another form such as a dauber, a bottled free ink solution, a stamp pad, and the like. Preferably, the ink is disposed in a writing instrument and the writing instrument is for example, a ball-point pen, an extruded plastic porous tip pen, or a marker.
After a highlightable ink described herein is applied to a substrate, the solvents present in the ink (e.g., water) will substantially evaporate. Likewise, the solvents present in the eradicator fluid (e.g., water) will substantially or completely evaporate once the eradicator has been applied to the ink, leaving the eradication agent (e.g., sulfite, bisulfite) along with the ink components (e.g., eradicated dye, colored pigment). Thus, another aspect of the invention is a colored complex of the ink described herein with an eradicator fluid after the solvents have substantially or completely evaporated. The highlighted ink complex includes a colorless or substantially colorless dye selected from the group consisting of diarylmethane derivatives, triarylmethane derivatives, methine dyes, and combinations thereof, a colored pigment, and any optional additives described herein.
An ink is a mixture of components that impart different properties to the ink. For example, a surfactant can be used to improve the absorption of an ink by a substrate (e.g., paper), and a film-forming agent can be used to improve the adhesion of the resulting mark to the substrate. Thus, the ink disclosed herein can include one or more additives selected from the group consisting of pH buffers, surfactants, biocides, anticorrosive agents, sequestering agents, anti-crusting agents, rehology control agents, binder resins, and combinations thereof, in the amounts and proportions conventionally used in inks for various applications.
+EXAMPLES
The following examples are provided to illustrate the invention but is not intended to limit the scope of the invention.
Example 1
A highlightable ink was prepared with the ingredients identified below in the amounts shown:















Component
Function
Amount (wt. %)




















Water
Solvent
76.48



Propylene Glycol
Organic Solvent
19.12



Basic Green 4
Dye
0.96



LUCONYL 3855
Pigment
3.44










The propylene glycol (available from EM Science of Gibbstown, N.J.), was added at room temperature to the water and mixed until a homogenous, particulate-free solution was formed. The Basic Green 4 dye was then added to this solution and the solution was mixed until the dye were fully dissolved. The pigment was then added and the solution was mixed for an hour until a homogenous solution was formed.
The resulting ink was then put into a SHARPIE marker and applied to a sheet of white paper to determine the color of the ink once applied to a substrate. The ink was observed to be a dark green color.
As described above, it is believed that the major contributing factor to the length of time it takes to highlight an ink described herein is proportional to the weight percent of eradicable dye present in the ink. Thus, after the ink was applied to a white sheet of paper, the eradication time was tested with a commercially available eradicator solution available from Sanford Reynolds of Valence, France. Upon the application of the eradication solution to the marking, the marking changed in color from a dark green to a red, and this conversion took approximately five seconds.
The foregoing description is given for clearness of understanding only, and no unnecessary limitations should be understood therefrom, as modifications within the scope of the invention may be apparent to those having ordinary skill in the art. Throughout the specification, where compositions are described as including components or materials, it is contemplated that the compositions can also consist essentially of, or consist of, any combination of the recited components or materials, unless stated otherwise.

## Claims

1. A writing and highlighting system comprising:
a writing instrument containing a marking composition disposed therein; and
an eradicator fluid,
the marking composition comprising an aqueous mixture of a colored pigment and an eradicable dye selected from the group consisting of diarylmethane derivatives,
triarylmethane derivatives, methine dyes, and combinations thereof, wherein said mixture and said colored pigment are different colors.

2. The writing and highlighting system of claim 1, wherein said mixture is green.

3. The writing and highlighting system of claim 1, wherein said colored pigment is red.

4. The writing and highlighting system of claim 1, wherein the color of said colored pigment is substantially unaffected by an oxidizing agent.

5. The writing and highlighting system of claim 1, wherein the color of said colored pigment is substantially unaffected by a change in the pH of said mixture.

6. The writing and highlighting system of claim 1, wherein said colored pigment is present in an amount in a range of about 0.01% to about 20% by weight of the total weight of the composition.

7. The writing and highlighting system of claim 6, wherein said colored pigment is present in an amount in a range of about 0.1% to about 8% by weight of the total weight of the composition.

8. The writing and highlighting system of claim 1, wherein said dye is selected from the group consisting of Auramine O, Basic Yellow 2, Basic Yellow 11, Basic Yellow 13, Basic Yellow 21, Basic Yellow 28, Basic Yellow 29, Basic Yellow 40, Acid Blue 22, Acid Blue 93, Acid Green 5, Basic Blue 8, Basic Blue 15, Basic Blue 20, Basic Blue 26, Basic Fuchsin, Basic Green 4, Ethyl Green, Fast Green Fcf, Food Green 3, Malachite Green, Methyl Blue, Methyl Green, Mordant Blue 3, and combinations thereof.

9. The writing and highlighting system of claim 1, wherein said dye is present in an amount in a range of about 0.01% to about 10% by weight of the total weight of the composition.

10. The writing and highlighting system of claim 9, wherein said dye is present in an amount in a range of about 0.1% to about 6% by weight of the total weight of the composition.

11. The writing and highlighting system of claim 1, wherein the marking composition further comprises a binder resin.

12. The writing and highlighting system of claim 11, wherein said binder resin is selected from the group consisting of polyethylene glycol, polyvinylpyrrolidone and copolymers and salts thereof, polyvinylacetate and copolymers and salts thereof, polyacrylic acid and copolymers end salts thereof, and combinations of the foregoing.

13. The writing and highlighting system of claim 1, wherein said marking composition further comprises an organic solvent.

14. The writing and highlighting system of claim 13, wherein said organic solvent is selected from the group consisting of glycols, ureas, fatty alcohols, dimethylformamide, formamide, dimethylsulfoxide, high molecular weight hydrocarbons, low molecular weight hydrocarbons, and combinations thereof.

15. The writing and highlighting system of claim 13, wherein said solvent is present in an amount in a range of about 5% to about 30% by weight based on the total weight of the composition.

16. The writing and highlighting system of claim 1, wherein said marking composition further comprises an additive selected from the group consisting of pH buffers, surfactants, biocides, anticorrosive agents, sequestering agents, anti-crusting agents, rheology control agents, binder resins, and combinations thereof.

17. A method of writing and highlighting, comprising the steps of writing on a substrate with a writing instrument containing an ink comprising an aqueous mixture of a colored pigment and an eradicable dye selected from the group consisting of diarylmethane derivatives, triarylmethane derivatives, methine dyes, and combinations thereof, wherein said mixture and said colored pigment are different colors, and applying an eradicator fluid to at least a portion of said writing, thereby highlighting said portion of the writing by at least substantially eradicating the eradicable dye.

18. The method of claim 17, wherein said substrate is paper.

19. The method of claim 17, wherein the color of said colored pigment is substantially unaffected by a reducing agent selected from the group consisting of a sulfite reducing agent, a bisulfite reducing agent, and combinations thereof.

20. The writing and highlighting system of claim 1, wherein the color of said colored pigment is substantially unaffected by a reducing agent.

21. The writing and highlighting system of claim 1, wherein the color of said colored pigment is substantially unaffected by a reducing agent selected from the group consisting of a sulfite reducing agent, a bisulfite reducing agent, and combinations thereof.

22. The writing and highlighting system of claim 1, wherein said eradicator fluid comprises an oxidizing agent.

23. The writing and highlighting system of claim 20 wherein said eradicator fluid comprises a reducing agent.

24. The writing and highlighting system of claim 21, wherein said eradicator fluid comprises a reducing agent selected from the group consisting of a sulfite reducing agent, a bisulfite reducing agent, and combinations thereof.

25. The writing and highlighting system of claim 1, wherein said writing instrument is a pen or a marker.

26. The writing and highlighting system of claim 25, wherein said writing instrument is a pen selected from a ball-point pen and an extruded plastic porous tip pen.

27. The writing and highlighting system of claim 1, wherein the eradicator fluid is disposed in a writing instrument.

28. The method of claim 17, wherein the color of said colored pigment is substantially unaffected by a reducing agent.

29. The method of claim 19, wherein said eradicator fluid comprises an agent selected from the group consisting of a sulfite, a bisulfite, and combinations thereof.

30. The method of claim 17, wherein said writing instrument is a pen or a marker.

31. The method of claim 30, wherein said writing instrument is a pen selected from a ball-point pen and an extruded plastic porous tip pen.

32. The method of claim 17, wherein the eradicator fluid is disposed in a writing instrument.

33. A writing and highlighting system comprising:
a writing instrument selected from a pen and a marker containing a marking composition disposed therein; and
an eradicator fluid,
the marking composition comprising (a) an aqueous mixture of a colored pigment present in an amount in a range of about 0.01% to about 50% by weight of the total weight of the composition, wherein the color of said colored pigment is substantially unaffected by a reducing agent selected from the group consisting of a sulfite reducing agent, a bisulfite reducing agent, and combinations thereof, (b) an eradicable dye present in an amount in a range of about 0.01% to about 10% by weight of the total weight of the composition and selected from the group consisting of diarylmethane derivatives, triarylmethane derivatives, methine dyes, and combinations thereof, (c) a binder resin; and (d) an organic solvent, wherein said mixture and said colored pigment are different colors.