Abstract: An ink composition, including: a water-soluble solvent A; a pigment; and water. The water-soluble solvent A contains at least a water-soluble solvent having an SP value of 27.5 or less at an amount of 90 mass % or more and a compound represented by the following Formula (1), wherein the compound represented by Formula (1) is the same as or different from the water-soluble solvent having an SP value of 27.5 or less: wherein, in Formula (1), l, m and n each independently represent an integer of 1 or more, the total of l, m and n is from 3 to 15, and AOs each independently represents an ethyleneoxy group or propyleneoxy group.

Abstract: The present invention relates to an ink set containing chromophoric metals for digital printing on ceramic materials additive-treated with silica and titanium dioxide, a process for decorating ceramic materials by digital printing using said ink set and decorated ceramic articles obtainable by said process.

Abstract: Ceramic inks comprising ceramic pigments dispersed in vehicles based on water and glycols and containing urea, and method for decorating green or fired ceramic bodies by the use of said inks.

Abstract: Ink sets can include a plurality of aqueous inks. In one embodiment, a first ink can include a magenta dye and a magenta pigment. A second ink can include a cyan pigment, and a third ink can include a yellow pigment, wherein the second and third inks are substantially devoid of dye. The inks can independently include 2-pyrrolidone or 2-hydroxyethyl-2-pyrrolidone and an additional solvent selected from a glycol, a second pyrrolidone, and mixtures thereof. In another embodiment, an aqueous ink-jet ink can comprise a pigment and a liquid vehicle including water, 2-pyrrolidone, 2-hydroxyethyl-2-pyrrolidone, tetraethylene glycol, and 1,6-hexanediol.

Abstract: A solid ink composition suitable for ink jet printing, including printing on coated paper substrates. In embodiments, the solid ink composition comprises both a crystalline compound and an amorphous compound, and optionally, in combination, an organic pigment, which provides for a robust, rapid crystallization ink composition.

Abstract: There is disclosed an ink composition and a method of printing and using ink on substrate material comprising polyvinyl chloride with thermal inkjet, drop on demand piezo inkjet, or continuous inkjet by depositing ink comprising vinyl-penetrating solvent, colorant and non-aqueous carrier solvent, the ink being free from polymerizable resins and binders.

Abstract: The object of the invention is to provide an inkjet recording oil green ink composition that excels more in terms of all the quality of prints, stability on printing, the ability of prints to be dried, and ink storage stability, and is capable of making wider a color reproduction area expressed by yellow and cyan. The inkjet recording oil green ink composition contains as an organic green pigment coloring agent C. I. Pigment Green 58 comprising a (poly) halogenated zinc phthalocyanine. The invention also provides an ink set comprises the inventive oil green ink composition and further includes at least an oil yellow ink composition and an oil cyan ink composition.

Abstract: An inkjet ink comprising water, colorant, and a dynamic surface active agent at an effective concentration such that dynamic surface tension DST20 min at 20 minutes universal surface age is less than each of dynamic surface tension DST1 sec at 1 second universal surface age and dynamic surface tension DST10 sec at 10 seconds universal surface age, and the difference between DST10 sec and DST20 min is greater than 9.2 mN/m at 21° C. or the difference between DST1 sec and DST20 min is greater than 15.5 mN/m at 21° C., and static surface tension of the ink is less than 50 mN/m. Large dynamic surface tension differences between the indicated time scales yield an optical density improvement in printed images. Anionic fluorosurfactant comprising a phosphate group at concentrations up to about 1 weight percent enables a combination of high optical density and good felt wetting in inkjet cartridges.

Abstract: [Problem to be solved] A non-aqueous ink, which has excellent pigment dispersion stability and can achieve reduction or elimination of print-through, thereby achieving high print density, is disclosed. [Solution] The non-aqueous ink contains at least a pigment and an organic solvent, wherein the organic solvent contains a five-membered heterocyclic compound having a C?O bond in an amount of 50 mass % or more of the organic solvent, and the content of a polymer component in the ink is 20 mass % or less relative to the pigment.

Abstract: The present invention provides a magenta recording ink composition including at least a solid solution pigment (A) containing quinacridone, a lake pigment (B) having a xanthene structure, an aqueous solvent, and water, wherein the solid solution pigment (A) has visible light absorption peaks at wavelength ranges of from 510 nm to 530 nm and from 540 nm to 560 nm, and a mass ratio (B/A) of the lake pigment (B) to the solid solution pigment (A) falls within the range of 0.1 to 5.

Abstract: An ink for ink-jet recording apparatuses, includes water, a pigment dispersion, and a super-penetrating agent and a high SP organic solvent respectively having a predetermined solubility parameter (SP value). All of differences (?SPs) between SP values of the neighboring organic solvents are from 0.5 to 5.0 in order of SP values thereof, and the difference of SPmax?SPmin is 12 or less in which SPmax is the highest SP value of an organic solvent among organic solvents in the high SP organic solvent and SPmin is the smallest SP value of an organic solvent among organic solvents in the super-penetrating agent.

Abstract: [Problem to be solved] A non-aqueous pigment ink is disclosed, which can eliminate or reduce striking through while ensuring pigment dispersion stability and ejection stability, and achieve high print density. Also, a non-aqueous inkjet ink is disclosed, which can reduce the time required for warming up the ink while ensuring the pigment dispersion stability and the ejection stability. [Solution] As the first aspect, the non-aqueous pigment ink contains at least a non-aqueous solvent and a pigment that is self-dispersed in the solvent, wherein the self-dispersed pigment is treated with a compound represented by R1—X or R2—Y—R3, where X is any of —SH, —NCO, —NH2 and —NHR (where R is an alkyl group), Y is any of —CO—O—O—CO— and —CO—O—O—, R1, R2 and R3 are alkyl groups with a carbon number of 8-22, the alkyl groups may be linear or branched, and R2 and R3 may be the same with or different from each other.

Abstract: An ink for ink-jet recording apparatuses includes water, a pigment dispersion, a humectant, and a penetrating agent. The ink includes glycerin of from 5% to 9% by mass and 1,3-propanediol and/or 1,4-butanediol of from 30% to 45% by mass as the humectant. The ink also includes a C1-C4 monoalkyl ether of polyhydric alcohol of from 2.0% to 4.5% by mass as the penetrating agent.

Abstract: A solid dispersion of pigment for an aqueous composition includes a pigment and an ethoxylated alcohol. The solid dispersion of pigment is adapted for being directly incorporated into the aqueous composition with reduced shear for coloration. A method of preparing a solid dispersion of pigment for an aqueous composition with reduced shear mixing includes heating the mixture of an ethoxylated alcohol and a pigment, and cooling the mixture to obtain the solid dispersion of pigment.

Abstract: It is an object of the present invention to provide an ink set which makes it possible to obtain recorded images that have a broad color reproduction range and a high saturation, as well as glossiness without conspicuous graininess caused by dot expression, and which in particular makes it possible to achieve an extreme suppression of graininess caused by dot expression in cases where the ink set is used on media that have a coating layer, and to obtain recorded images with extremely superior coloring characteristics in cases where the ink set is used on ordinary paper. The present invention provides an ink set comprising at least a yellow ink (Y), magenta ink (M), cyan ink (C) and red ink (R), wherein the L* values in the CIE-stipulated Lab display system of aqueous solutions of the respective inks diluted 1000 times by weight are in the following ranges: (Y): at least 89 but no more than 94, (M): at least 76 but no more than 93, (C): at least 74 and no more than 87, (R): at least 55 and no more than 74.

Abstract: Disclosed herein are an ink containing a self-dispersible pigment and a salt, wherein the self-dispersible pigment is a pigment to the surface of a particle of which a functional group containing at least a group having a hydrogen bonding property and two phosphonic acid groups is bonded, counter ions of the two phosphonic acid groups containing one of K+ and NH4+; the salt is constituted by combining at least one cation of K+ and NH4+ with at least one anion selected from the group consisting of Cl?, Br?, I?, ClO?, ClO2?, ClO3?, ClO4?, NO2?, NO3?, SO42?, CO32?, HCO3?, HCOO?, (COO?)2, COOH(COO?), CH3COO?, C2H4 (COO?)2, C6H5COO?, C6H4(COO?)2, PO43?, HPO42? and H2PO4?; a cation concentration in the ink is 0.04 mol/L or more; and the viscosity of a liquid obtained by evaporating 15% by mass of the ink is less than 3.5 mPa·s at 25° C.

Abstract: This invention provides a magenta ink composition that, when recorded, is excellent in color development, graininess, and gloss, is less likely to cause clogging in an ink jet recording head, and is excellent in color reproduction in a high-chroma and high-lightness red region. The magenta ink composition has an L* value of not less than 60 and a b* value of not more than ?17 when the a* value in CIE standard calculated from a visible absorption spectrum in a not more than 10000-fold diluted aqueous solution is 80.

Abstract: An inkjet-recording non-aqueous ink composition including a metallic pigment, an organic solvent, and a cellulose acetate butyrate resin having a butyl content of 16.5 to 48%.

Abstract: A black ink composition is provided. The black ink composition includes a dispersive black colorant; less than 1 wt % of a glycol ether compound based on total weight of the black ink composition; a solvent; and water. The black ink composition of the present invention is free of surfactants and has excellent compatibility with a nozzle, and thus provides good smoothness in printing and high-quality image.

Abstract: An ink jet ink including a self-dispersible pigment, a salt, a polyoxyethylene alkyl ether and a water-soluble organic solvent. The self-dispersible pigment is a pigment to a surface of a particle of which a functional group containing at least a phosphonic acid group is bonded, the introduced amount of the functional group bonded to the self-dispersible pigment is 0.10 to 0.33 mmol/g. The salt is constituted by combining a specific cation with a specific anion. The value (Concentration of anion)×(Valence number of anion) of the salt in the ink is 0.005 to 0.06 mol/L. The water-soluble organic solvent includes glycerol, the content of which in the ink is 35% to 78% by mass based on the total content of the water-soluble organic solvent in the ink.

Abstract: An ink set is provided which includes a first ink containing a first pigment, water, and a glycol ether having an HLB value, measured by Davies method, in the range of 4.2 to 8.0, and a second ink substantially not containing the glycol ether. The second ink contains a second pigment and water.

Abstract: The present invention is drawn to ink compositions and methods for ink-jet recording. The ink-jet ink can comprise water and at least 20 wt % solids. The solids can include pigment particulates and silica particulates dispersed in the ink-jet ink, as well as solid humectant substantially dissolved in the ink-jet ink. The pigment particulates, silica particulates, and solid humectant substantially remain with a dried image that is printed using the ink-jet ink of the present invention.

Abstract: An ink-jet recording ink including water, a water-soluble organic solvent, a pigment as a colorant (B), and at least one fluorochemical surfactant selected from compounds represented by Structural Formula (1) below, Structural Formula (1) where R1 denotes any one of a hydrogen atom, an alkyl group and a perfluoroalkyl group, R2 denotes any one of a hydrogen atom, an alkyl group and a fluorine-containing group, Rf denotes a fluorine-containing group, and m and n each denote an integer of 1 or greater.

Abstract: In an inkjet recording system using an ink in which a coloring material is dispersed in a solvent with a dispersing agent, printing density is improved by causing aggregation of the coloring material contained in the ink that has been ejected onto a printing medium. In an inkjet printing method, printing is performed by ejecting one of first and second inks onto a printing medium, and then successively ejecting the other ink so as to overlay it on the one ink. The first ink includes a first solvent, a coloring material, and a dispersing agent. The second ink includes at least a second solvent capable of changing solubility of the dispersing agent to cause aggregation of the coloring material when it is mixed with the first ink. For example, when one of the first and second solvents includes a water-insoluble organic solvent, the other can include a water-soluble organic solvent.

Abstract: A recrystallization type of ink composition comprises a solvent, a crystalline material, and a colorant. When the recrystallization type of ink composition is applied to a non-absorption surface such as a whiteboard, a glass surface, and a plastic surface, it is recrystallized to provide a visual effect of a metal sense at the applied part.

Abstract: The present disclosure is directed to a pigment preparation comprising aluminum effect pigments, a solvent and at least one additive, wherein the aluminium effect pigments have a d98 value of the volume averaged particle size distribution curve of less than 15 ?m, the at least one additive is a phosphorous containing additive, and the solvent has a viscosity equal to or more than 1.8 mPa's at 25° C. The disclosure is further directed to an ink jet printing ink as well the use thereof.

Abstract: Disclosed are methods of printing high resolution images on edible substrates with dispersed pigmented inks using a drop-on-demand ink-jet printer. Dispersed pigmented white inks useful with the inventive methods are also disclosed. White images having a resolution greater than 200 dpi can be printed on chocolate using the methods and inks disclosed herein. The inventive methods and inks may also be integrated with a consumer-driven site vending or e-commerce application in which the consumer provides the image to be printed and edibles bearing the printed image are prepared for rapid turnaround.

Abstract: According to one embodiment, an aqueous inkjet ink includes a dispersion medium that contains water and a water-soluble polyhydric alcohol having a weight average molecular weight of 400 or more, and a pigment. The pigment accounts for less than 5 mass % of the total amount of the aqueous inkjet ink. The aqueous inkjet ink has viscosities (mPa·s) measured using a cone-plate type viscometer at 20 rpm and satisfying the following relationships: VA/VB?1.5 VA?10 mPa·s 3 mPa·s?VB?15 mPa·s, where VA is the viscosity at 30° C., and VB the viscosity at 45° C.

Abstract: An inkjet printer includes an inkjet printhead having a plurality of color planes for ejecting a plurality of different inks. Each color plane has a nozzle row defined in a nozzle face of the printhead and each nozzle in a respective color plane is supplied with a same ink. The printhead is plumbed such that a first color plane ejecting a first ink having a relatively low luminance is sandwiched between second and third color planes ejecting respective second and third inks having a relatively high luminance A plurality of ink reservoirs are in fluid communication with the printhead, the ink reservoirs containing the first, second and third inks. An amount of surfactant in the first ink is at least 0.4 wt % greater than an amount of surfactant in the second and third inks.

Abstract: The present invention provides an ink for inkjet printing. The ink contains an aqueous vehicle, a pigment colorant and an effective amount of a bleed control agent selected from benzyl glycerol, 3-phenoxy-1,2-propanediol and any combination thereof. The ink exhibits reduced intercolor bleed when printed, for example, on plain paper.

Abstract: Provided is an aqueous ink capable of recording an image achieving a high level of both of color developability and lightfastness. The aqueous ink includes a first pigment and a second pigment. The first pigment is C.I. Pigment Yellow 213, and the second pigment is at least one selected from the group consisting of C.I. Pigment Yellows 93, 128, 138, 151, 155, 180, and 215. The content A (% by mass) of the first pigment and the content B (% by mass) of the second pigment based on a total mass of the ink satisfy a relationship of 0.1?A/(A+B)?0.9. The ink further includes a water-soluble organic solvent having an SP value (unit: (cal/cm3)1/2) determined by Fedors' method of 11.0 or more and 16.0 or less.

Abstract: A solid ink that includes an ink carrier and a resinous compound of the formulas or a salt thereof, wherein G1 is —X1C(O)OR1, —X2OC(O)R2, or —X2OH; G2 is R4, R12, —C(O)R2, —C(O)X1C(O)OR1, or —C(O)X2OC(O)R2; R1 is an alkyl having from 10 to 80 carbon atoms; R2 is an alkyl having from 2 to 40 carbon atoms; each R3 and R4 is independently hydrogen, alkyl, arylalkyl or alkylaryl; each R5 and each R6 is independently hydrogen or alkyl; X1 and X2 are both a straight or branched alkylene group; t1 is 1 to 20; t2 and t3 is independently 0 to 20; u1 is 1 to 30; u2 and u3 is independently 0 to 30; each R7 and each R8 is independently hydrogen, alkyl, or alkoxyl; each R9 and each R10 is independently hydrogen, alkyl, or alkoxyl; Ar is a substituted or unsubstituted aromatic moiety; p is 1 to 5; q is 1 to 12; A? is selected from the group consisting of Cl?, Br?, I?, HSO4?, HSO3?, CH3SO3?, NO3?, HCOO?, CH3COO?, H2PO4?, SCN?, ClO4?, SSO3?, PF6?, and SbCl6?; and J is alkyl, arylalkyl, or alkylaryl.

Abstract: An oily inkjet ink comprises a pigment, a dispersant, and a water-insoluble organic solvent, wherein an ester solvent contained in the water-insoluble organic solvent is an ester solvent that is represented by the general formula: CnHx—COO—CmH2m+1, in which n represents an integral number falling within the range of 8 to 15, m represents an integral number falling within the range of 4 to 7, and x represents a number falling within the range of 2n?1 to 2n+1. The ester solvent is contained in a containing quantity falling within the range of 10% by mass to 30% by mass with respect to the total quantity of the ink.

Abstract: The present invention provides an ink composition comprising pigment particles covered with a water-insoluble resin, resin particles, a water-soluble organic solvent, water, and a solid wetting agent in an amount of 5% by mass or more.

Abstract: An inkjet recording liquid includes: water; at least one colorant; and a water-soluble organic solvent having an SP (solubility parameter) value of 27.5 or less at a content of 70 mass % or more with respect to the total amount of water-soluble organic solvent, wherein the water-soluble organic solvent having an SP value of 27.5 or less includes at least one water-soluble organic solvent having a molecular weight of from 240 to 1400 and represented by the following Formula (1) at a content of 70 mass % or more with respect to the amount of the water-soluble organic solvent having an SP value of 27.5 or less. R-An-OH ??Formula (1) In Formula (1), R represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a group derived from a sugar alcohol having 3 to 12 carbon atoms; each A independently represents an ethyleneoxy group or a propyleneoxy group; and n represents an integer of from 3 to 24.

Abstract: According to one embodiment, an inkjet aqueous ink includes water, a pigment, a water-soluble organic solvent, a poorly water-soluble compound, a solubilizer that solubilizes the poorly water-soluble compound in water, and an acetylene glycol-based surfactant. The poorly water-soluble compound is 2,5,8,11-tetramethyl-6-dodecyne-5,8-diol. The solubilizer is selected from polyoxyethylene anionic surfactants and non-ionic surfactants.

Abstract: A water-based ink for ink jet recording, containing: a coloring agent; water; and a water-soluble organic solvent. The coloring agent contains a phosphate group-modified self-dispersing pigment. The water-based ink further contains at least one of a reducing sugar and a sugar alcohol and a calcium ion.

Abstract: The present invention provides an ink-media set, record printed by use of the ink-media set, an inkjet printing method, and an inkjet printing apparatus which includes ink that has at least water, dye, and humectant and surface tension thereof is 20 to 35 mN/m at 25° C., a support, and a recording medium having the support and at least one surface thereof has a coating layer wherein transfer rate of the ink to the recording medium measured by a dynamic scanning absorptometer in 100 ms of contact time is 4 to 15 ml/m2 and transfer rate of the ink to the recording medium measured by a dynamic scanning absorptometer in 400 ms of contact time is 7 to 20 ml/m2.

Abstract: A water-based ink for inkjet recording exhibits a blue color defined as L*<45, 25<C*<28, 255<h<278, and comprises a mixture of dyes and pigments, glycerol and polyethylene glycol #200 as water-soluble organic solvents and a polymeric dispersant. The ink will preferably have a ratio of glycerol to polyethylene glycol 200 within the range of from 2:1 to 3.5 1. The water-based ink preferably includes C.I. Pigment Blue 60 as a colorant and provides good printing stability and good storage stability. Tests show the inks to have good jettability.

Abstract: The invention provides an ink jet recording ink containing a self-dispersion pigment having a lactone group and a carboxyl group, an organic carboxylic acid salt, water and a water-soluble substance having a coefficient of hydrophilicity-hydrophobicity of 0.37 or more as defined by the following equation (A), and having a surface tension of 34 mN/m or less.

Abstract: Metal nanoink (100) for bonding an electrode of a semiconductor die and an electrode of a substrate and/or bonding an electrode of a semiconductor die and an electrode of another semiconductor die by sintering under pressure is produced by injecting oxygen into an organic solvent (105) in the form of oxygen nanobubbles (125) or oxygen bubbles (121) either before or after metal nanoparticles (101) whose surfaces are coated with a dispersant (102) are mixed into the organic solvent (105). Bumps are formed on the electrode of the semiconductor die and the electrode of the substrate by ejecting microdroplets of the metal nanoink (100) onto the electrodes, the semiconductor die is turned upside down and overlapped in alignment over the substrate, and then, the metal nanoparticles of the bumps are sintered under pressure by pressing and heating the bumps between the electrodes. As a result, generation of voids during sintering under pressure is minimized.

Abstract: This invention provides a metallic pigment, which can prepare a printed matter having metallic luster, can realize stable printing even in a printer with ink jet nozzles having a nozzle diameter of not more than 30 ?m, can eliminate the need to carry out heat treatment and the like, and, thus, can realize ink jet recording without undergoing a limitation on printing media (recording media), an ink composition, and an ink jet recording method. The metallic pigment is a metal foil piece having an average thickness of 30 to 100 ?m, having a 50% average particle diameter of not less than 0.5 ?m and not more than 4.0 ?m, and having such a particle size distribution that the maximum particle diameter is not more than 12 ?m.

Abstract: The present invention is directed to a printable composition, comprising: 0.5 to 60 wt % of a polymer selected from the group consisting of epoxy, Novolac and poly(dimethylglutarimide); and 40-99.5 wt % of a solvent composition comprising (1) a high boiling point solvent having a flash point greater than about 10° C. and a boiling point greater than about 130° C. and (2) a low boiling point solvent having a flash point less than 30° C. and a boiling point less than or equal to 130° C., all weight percents based on the total weight of the composition. The present invention is also directed to methods of forming patterned substrates using the above compositions. The compositions of the invention are useful for printing electronic materials onto a substrate using a piezo-electric printer.

Abstract: The present invention is directed to a printable composition, comprising: 0.5 to 60 wt % of a polymer selected from the group consisting of epoxy, Novolac and poly(dimethylglutarimide); and 40-99.5 wt % of a solvent composition comprising (1) a high boiling point solvent having a flash point greater than about 10° C. and a boiling point greater than about 130° C. and (2) a low boiling point solvent having a flash point less than 30° C. and a boiling point less than or equal to 130° C., all weight percents based on the total weight of the composition. The present invention is also directed to methods of forming patterned substrates using the above compositions. The compositions of the invention are useful for printing electronic materials onto a substrate using a piezo-electric printer.

Abstract: An oily inkjet ink comprises a pigment, a dispersant, and an organic solvent. The organic solvent contains an ester solvent and/or an alcohol solvent. A containing quantity of a water-soluble ingredient in the pigment is equal to at most 0.15% by mass.

Abstract: The present disclosure relates to mixtures of non-aromatic solvents which can be used for the manufacture of varnishes and printing inks in particular for planographic printing (or offset printing). These mixtures of solvents include from 80 to 99.5% by mass of a slightly aromatic hydrocarbon oil and from 0.5 to 20% by mass of a composition composed predominantly of saturated and/or unsaturated C16 to C22 monocarboxylic fatty acids, optionally in a mixture with resin acids (unsaturated polycyclic—in particular tricyclic—monocarboxylic acids).

Abstract: An ink composition for inkjet printing by the continuous deflected jet technique, which is liquid at ambient temperature, comprising: a) a binder; b) one or more dyes and/or pigments; and c) a solvent, in which: said solvent comprises at least 10% by weight—relative to the total weight of the ink composition—of at least one noncyclic acetal, and at least 5% by weight of one or more other organic compounds capable of dissociating the ionizable species that are found in the ink.

Abstract: A surface treatment solution for a recording paper on which ink-jet recording is performed with a water-based ink, the surface treatment solution includes calcium alginate which is contained by 0.008 wt % to 0.074 wt % in the surface treatment solution, sodium alginate which is contained by 0.013 wt % to 0.084 wt % in the surface treatment solution, a water-soluble organic solvent, and water.

Abstract: An ink contains at least a pigment, wherein the pigment is a solid solution of C.I. Pigment Red 202 and C.I. Pigment Violet 19, and a primary particle diameter D (nm) of the pigment and a 50%-cumulative diameter D50 (nm) in particle diameter distribution of the pigment satisfy a relation of D×0.95?(=<)D50?(=<)130, and a 90%-cumulative diameter D90 (nm) in particle diameter distribution of the pigment and the 50%-cumulative diameter D50 (nm) satisfy a relation of 1.5?(=<)D90/D50?(=<)2.2.

Abstract: Compositions, systems, and methods for ink-jet printing having improved black to color bleed control, reduced wicking, and/or reduced halo are described. The composition can include a functionalized carbon pigment dispersed in an ink vehicle. The carbon pigment includes functional groups chemically attached thereto. Suitable functional groups includes an aromatic ring structure having multiple carboxyl groups (or salts thereof) attached to the aromatic ring structure, wherein at least two of the multiple carboxyl groups are positioned on adjacent carbon atoms of the aromatic ring structure.