Solvent-based inkjet inks

Abstract

An inkjet ink that includes a rosin resin having an acid value of less than 22 mgKOH / g and a hydroxyl value of 40 mg KOH / g or less, an alcohol, and a cosolvent having a Hildebrand solubility parameter of less than 11 cal1 / 2 cm−3 / 2. The inkjet ink is characterized by extended decap times at a range of environmental conditions, and furthermore has good running stability and dry time. A printed article including the inkjet ink in dried form, and a method of forming a printed image with a thermal inkjet printhead are also provided.

Description

[0001] TITLE

[0002] SOLVENT-BASED INKJET INKS

[0003] CROSS-REFERENCE TO RELATED APPLICATIONS

[0004] The present application is based on and claims the benefit of priority to International Patent Application PCT / US2023 / 014036, filed February 28, 2023. The entire content of this application is incorporated herein by reference.

[0005] BACKGROUND OF THE INVENTION

[0006] TECHNICAL FIELD

[0007] The present invention relates to solvent-based inkjet inks, methods of preparing such an inkjet ink, and methods of forming an image with such an inkjet ink.

[0008] DESCRIPTION OF THE RELATED ART

[0009] The “background” description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present invention.

[0010] Thermal inkjet (TIJ) printing is a desirable technology for printing, coding, and marking as it offers high print resolutions at lower costs than competing technologies in the field, such as continuous inkjet (CIJ) methods. In thermal inkjet printing processes, the print cartridges contain a series of tiny chambers, each containing a heater, which produce ink droplets from thermal vaporization of an ink solvent. In the jetting process, a resistor is heated rapidly to produce a vapor bubble (hence the phrase “bubblejet”), which subsequently ejects a droplet from the orifice. This process is extremely efficient and reproducible, and modern TIJ printheads for industrial graphics applications can generate uniform droplets of 4 pL or smaller in volume at frequencies of 36 kHz or greater.

[0011] However, industrial marking and coding regularly requires the printing of essential information — such as personal information, labels, codes, dating (e.g., expirations dates), and traceability information (e.g., manufacturing lot) — onto substrates. Such printing furthermore occurs in a variety of environmental conditions, for instance, printing in a cold room to label refrigerated food products, or printing in a warm outdoor environment to mark lumber products. Thermal inkjet printing can be troubled by poor reliability after periods of inactivity. For example, some inkjet inks suffer from short decap times, in which solvent losses due to prolonged exposure to air within an uncapped printhead leads to clogging / plugging of printhead nozzles, and thus unreliable ink jetting and image quality erosion over time. This degradation in image quality tends to be more acute at cold temperature / low humidities and warmer temperatures / higher humidities. Poor image quality is unacceptable for many applications, but particularly so for marking and coding of essential information. For this reason, even despite the other advantages, TIJ technology has had only modest acceptance in marking / coding applications and is limited by environmental conditions.

[0012] Solvent-based inkjet inks made using specific combinations of phenol resins, rosin resin esters, and organic solvents have been reported previously to possess acceptable decap times, see US20180072902A1 — incorporated herein by reference in its entirety. However, such ink systems are not compared between cold and dry versus warm and humid environments.

[0013] BRIEF SUMMARY OF THE INVENTION In view of the forgoing, there is a need for inkjet inks that have extended decap times, including across a range of temperatures and humidities.

[0014] Accordingly, it is one object of the present invention to provide novel inkjet inks that meet these criteria.

[0015] It is another object of the present disclosure to provide novel printed articles which contain a dried form of the inkjet inks.

[0016] It is another object of the present disclosure to provide novel methods of forming a printed image on a substrate by applying the inkjet inks onto the substrate and drying.

[0017] These and other objects, which will become apparent during the following detailed description, have been achieved by the inventors’ discovery that the combination of a rosin resin having both an acid value of less than 22 mgKOH / g and a hydroxyl value of 40 mgKOH / g or less, an alcohol, and a cosolvent having a Hildebrand solubility parameter of less than 11 cal1 / 2cm3 2, provides inkjet inks characterized by extended decap times at a range of environmental conditions and good running stability.

[0018] Thus, the present invention provides:

[0019] (1) An inkjet ink, comprising:

[0020] (A) a rosin resin having an acid value of less than 22 mgKOH / g and a hydroxyl value of 40 mg KOH / g or less;

[0021] (Bl) an alcohol; and

[0022] (B2) a cosolvent having a Hildebrand solubility parameter of less than 11 cal1 / 2cm3 2, wherein a weight ratio of the cosolvent (B2) to the rosin resin (A) ((B2):(A)) is 1 : 1 to 10: 1..

[0023] (2) An inkjet ink, comprising: (A) a rosin resin having an acid value of less than 22 mgKOH / g and a hydroxyl value of 40 mg KOH / g or less; and

[0024] (B) a solvent system comprising:

[0025] (Bl) an alcohol, and

[0026] (B2) a cosolvent having a Hildebrand solubility parameter of less than 11 cal1 / 2cm3 2, wherein a weight ratio of the cosolvent (B2) to the rosin resin (A) ((B2):(A)) is 1 : 1 to 10: 1.

[0027] (3) The inkjet ink of (1) or (2), wherein the rosin resin (A) is present in an amount of 0.1 to 10 wt%, based on a total weight of the inkjet ink.

[0028] (4) The inkjet ink of any one of (1) to (3), wherein the rosin resin (A) comprises a modified rosin resin (Al).

[0029] (5) The inkjet ink of any one of (1) to (4), wherein the modified rosin resin (Al) comprises a rosin ester.

[0030] (6) The inkjet ink of (5), wherein the rosin ester comprises at least one selected from the group consisting of a glycerol ester of a hydrogenated rosin, a glycerol esterified rosin, a pentaerythritol ester of a hydrogenated rosin, a pentaerythritol esterified rosin, a triethylene glycol esterified rosin, a maleic modified rosin ester, and a methyl esterified rosin.

[0031] (7) The inkjet ink of any one of (1) to (6), wherein the alcohol (Bl) is present in an amount of 75 to 90 wt%, based on a total weight of the inkjet ink. (8) The inkjet ink of any one of (1) to (7), wherein the alcohol (Bl) comprises at least one selected from the group consisting of methanol, ethanol, 1 -propanol, 2-propanol, 1- butanol, 2-butanol, 2-pentanol, 3 -pentanol, and t-amyl alcohol.

[0032] (9) The inkjet ink of any one of (1) to (8), wherein the alcohol (Bl) comprises ethanol.

[0033] (10) The inkjet ink of any one of (1) to (9), wherein the cosolvent (B2) is present in an amount of 1 to 20 wt%, based on a total weight of the inkjet ink.

[0034] (11) The inkjet ink of any one of (1) to (10), wherein the cosolvent (B2) is at least one selected from the group consisting of ethylene glycol monobutyl ether acetate, propylene glycol methyl ether acetate, acetone, and cyclohexanone.

[0035] (12) The inkjet ink of any one of (1) to (11), further comprising (C) a colorant.

[0036] (13) The inkjet ink of (12), wherein the colorant (C) is present in an amount of 0.1 to 15 wt%, based on a total weight of the inkjet ink.

[0037] (14) The inkjet ink of any one of (1) to (13), further comprising (D) a silicone.

[0038] (15) The inkjet ink of (14), wherein the silicone (D) is present in an amount of 0.001 to 4 wt%, based on a total weight of the inkjet ink. (16) The inkjet ink of any one of (1) to (15), further comprising (E) a pH adjuster in an amount of 0.1 to 5 wt%, based on a total weight of the inkjet ink.

[0039] (17) The inkjet ink of (16), wherein the pH adjuster (E) comprises an amine.

[0040] (18) The inkjet ink of (17), wherein the amine comprises an alkanolamine.

[0041] (19) A printed article, comprising: a substrate and a dried form of the inkjet ink of any one of (1) to (18) disposed on the substrate.

[0042] (20) A method of forming a printed image on a substrate, comprising: applying the inkjet ink of any one of (1) to (18) onto the substrate with a thermal inkjet printhead; and drying the inkjet ink.

[0043] BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The foregoing paragraphs have been provided by way of general introduction and are not intended to limit the scope of the following claims. The described embodiments, together with further advantages, will be best understood by reference to the following detailed description when considered in conjunction with the accompanying drawings, wherein:

[0045] Fig. 1 A illustrates the decap time evaluation for a “Good” rating, where the image has dimensions of 2.7 in x 0.5 in (6.9 cm x 1.8 cm).

[0046] Fig. IB illustrates the decap time evaluation for an “Acceptable” rating, where the image has dimensions of 2.7 in x 0.5 in (6.9 cm x 1.8 cm). Fig. 1C illustrates the decap time evaluation for a “Not Good” rating, where the image has dimensions of 2.7 in x 0.5 in (6.9 cm x 1.8 cm).

[0047] DETAILED DESCRIPTION OF THE EMBODIMENTS

[0048] In the following description, it is understood that other embodiments may be utilized and structural and operational changes may be made without departure from the scope of the present embodiments disclosed herein.

[0049] The present disclosure will be better understood with reference to the following definitions. As used herein, the words “a” and “an” and the like carry the meaning of “one or more” and “at least one.” Within the description of this disclosure, where a numerical limit or range is stated, the endpoints are included unless stated otherwise. It will be further understood that the terms “comprises” and / or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0050] The present disclosure also contemplates other embodiments “comprising”, “consisting of’ and “consisting essentially of’, the embodiments or elements presented herein, whether explicitly set forth or not. Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein. All patents and other references mentioned are incorporated in full herein by this reference, the same as if set forth at length.

[0051] As used herein, the words “about,” “approximately,” or “substantially similar” may be used when describing magnitude and / or position to indicate that the value and / or position described is within a reasonable expected range of values and / or positions. For example, a numeric value may have a value that is + / - 0.1% of the stated value (or range of values), + / - 1% of the stated value (or range of values), + / - 2% of the stated value (or range of values), + / - 5% of the stated value (or range of values), + / - 10% of the stated value (or range of values), + / - 15% of the stated value (or range of values), or + / - 20% of the stated value (or range of values). Within the description of this disclosure, where a numerical limit or range is stated, the endpoints are included unless stated otherwise. Also, all values and subranges within a numerical limit or range are specifically included as if explicitly written out.

[0052] The phrase “substantially free”, unless otherwise specified, describes an amount of a particular component in the inkjet ink being less than 1 wt%, preferably less than 0.5 wt%, more preferably less than 0.1 wt%, even more preferably less than 0.05 wt%, yet even more preferably 0 wt%, based on a total weight of the inkjet ink.

[0053] As used herein, the terms “optional” or “optionally” means that the subsequently described event(s) may or may not occur, or the subsequently described component s) may or may not be present (e.g., 0 wt%).

[0054] As used herein, “compound” is intended to refer to a chemical entity, whether as a solid, liquid, or gas, and whether in a crude mixture or isolated and purified.

[0055] The term “alkyl”, as used herein, unless otherwise specified, refers to a straight, branched, or cyclic, aliphatic fragment having at least 1, preferably at least 2, preferably at least 3, preferably at least 4 carbon atoms, and up to 22, preferably up to 20, preferably up to 18, preferably up to 12, preferably up to 8 carbon atoms. Examples of alkyl groups include, but are not limited to, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, pentyl, isopentyl, neopentyl, hexyl, isohexyl, 3 -methylpentyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl, lauryl, myristyl, cetyl, stearyl, and the like, including guerbet-type alkyl groups (e.g., 2- methylpentyl, 2-ethylhexyl, 2-proylheptyl, 2-butyloctyl, 2-pentylnonyl, 2-hexyldecyl, 2- heptylundecyl, 2-octyldodecyl, 2-nonyltridecyl, 2-decyltetradecyl, and 2-undecylpentadecyl). Cycloalkyl is a type of cyclized alkyl group. Exemplary cycloalkyl groups include, but are not limited to, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, norbomyl, and adamantyl.

[0056] As used herein, the term “fatty” describes a compound with a long-chain (linear) hydrophobic portion made up of hydrogen and anywhere from 8 to 22 carbon atoms, which may be fully saturated or partially unsaturated.

[0057] As used herein, the term “aryl” refers to an aromatic group containing only carbon in the aromatic ring(s), such as phenyl, biphenyl, naphthyl, anthracenyl, and the like.

[0058] The term “arylalkyl”, as used herein, refers to a straight, branched, or cyclic alkyl moiety (as defined above) that is substituted by an aryl group (as defined above) which may itself be optionally substituted by an alkyl group, examples of which include, but are not limited to, benzyl, phenethyl, 3 -phenylpropyl, 2-phenylpropyl, 1 -phenylpropyl, 4- phenylbutyl, 3 -phenylbutyl, 2-phenylbutyl, 2-methylbenzyl, 3 -methylbenzyl, 4-methylbenzyl, 2,4-dimethylbenzyl, 2-(4-ethylphenyl)ethyl, 3-(3-propylphenyl)propyl, and the like.

[0059] The term “(meth)acrylate” is used herein to refer to both acrylate and methacrylate groups. In other words, this term should be read as though “meth” is optional. Further, the term “(meth)acrylate” is used generally to refer to both acrylic acid-based compounds and acrylic ester-based compounds.

[0060] Throughout the specification, the term “boiling point” (b.p.) refers to the boiling point of a liquid measured at sea-level atmospheric pressure (i.e., 760 mmHg or 1 atmosphere), also called the normal boiling point, unless specified otherwise.

[0061] The term “decap behavior” herein, means the ability of the inkjet ink to readily eject from the printhead, upon prolonged exposure to air. The inkjet ink “decap time” is measured as the amount of time that an inkjet printhead may be left uncapped before the printer nozzles no longer fire properly, potentially because of clogging or plugging when printing resumes. Generally, nozzle(s) may become clogged (i.e., impeded, slowed) or plugged (i.e., obstructed, substantially or completely closed) by a viscous plug that forms in the nozzle(s) as a result of solvent loss, crusting of the ink, and / or kogation of various ink components in and / or around any of the nozzles. If a nozzle has become clogged, ink droplets ejected through the nozzle's orifice may be misdirected, which may adversely affect print quality. When an orifice is plugged, it becomes substantially or completely blocked. As a result of the nozzle being plugged, the ink droplets may not pass through the affected nozzle. Thus, the criteria for measuring failure to fire by a nozzle is a misdirection of ink through the nozzle’s orifice to a lesser or greater degree, or a complete blockage, which can be measured by visually inspecting a printed image.

[0062] Inkjet inks

[0063] The present disclosure is directed to inkjet inks that possess suitable physical and chemical stability at both ambient temperatures and printhead operating temperatures, are jetted reliably, have prolonged decap times in a very wide range of environmental conditions while still drying quickly after being applied onto a substrate, and have good running stability.

[0064] Inkjet inks of the present disclosure generally include the following components: (A) a rosin resin having an acid value of less than 22 mgKOH / g and a hydroxyl value of 40 mg KOH / g or less, (Bl) an alcohol, and (B2) a cosolvent having a Hildebrand solubility parameter of less than 11 cal1 / 2cm3 2.

[0065] The inkjet inks of the present disclosure may also optionally include one or more of (Al) a modified rosin resin, (C) a colorant, (D) a silicone, (E) a pH adjuster, and (F) an additive.

[0066] (A) Rosin Resin Inkjet inks of the present disclosure are formulated with a rosin resin (A). Typically, the rosin resin (A) is employed preferably in an amount of at least 0.1 wt%, at least 0.2 wt%, at least 0.4 wt%, at least 0.6 wt%, at least 0.8 wt%, at least 1.0 wt%, at least 1.1 wt%, at least 1.2 wt%, at least 1.4 wt%, at least 1.6 wt%, at least 1.8 wt%, at least 2 wt%, at least 2.2 wt%, at least 2.4 wt%, at least 2.5 wt%, and / or at most 10 wt%, at most 9 wt%, at most 8 wt%, at most 7 wt%, at most 6 wt%, at most 5.5 wt%, at most 5 wt%, based on a total weight of the inkjet ink. In one embodiment, the rosin resin (A) is present preferably in an amount of 0.1 to 10 wt%, more preferably 0.5 to 8 wt%, even more preferably 1.0 to 7wt%, even more preferably 1.5 to 6 wt%, or even more preferably 2.5 to 5 wt% based on a total weight of the inkjet ink.

[0067] The rosin resin (A) may be derived from gum rosin; wood rosin of grades B, C, D, E, F, FF, G, H, I, J, K, L, M, N, W-G, W-W (as defined by the ASTM 0509 standard); virgin rosin; hard rosin; yellow dip rosin; NF wood rosin; tall oil rosin; or colophony or colophonium as well as any of the single constituents of natural rosin qualities, e.g., abietic acid, abietinic acid, sylvic acid, dihydroabietic acid, tetrahydroabietic acid, dehydroabietic acid, neoabietic acid, pimaric acid, levopimaric acid, isopimaric acid, sandaracopimaric acid, palustric acid, dextro-pimaric acid, isodextro-pimaric acid, dextro-pimarinal, isodextro- pimarinal, xanthoperol, tatarol, podocarpic acid, phyllocladen, sugiol, ferruginol, himokiol, manool, manoyloxide, ketomanoyloxide, cativinic acid, eperuanic acid and all other rosin components based on the diterpene skeleton of abietic acid; as well as any mixtures thereof, which have at least one carboxylic, sulphonic or phosphoric acid available for silylation (via oxidation if necessary). The term “rosin” may indicate any mixtures of the chemical species mentioned above as well as any of the chemical species as such.

[0068] The rosin resin (A) preferably comprises modified rosin resins (Al). Such modified rosin resins may be formed by modifying the rosin resin through esterification, hydrogenation (including partial hydrogenation), dimerization, and / or other modifications / functionalization (e.g., through Diels- Alder reaction with an unsaturated di-acid like maleic or fumaric acid / anhydride, carboxylic acid reduction to the respective aldehydes / alcohols, double bond isomerization, dehydrogenation, oxidation, disproportionation, and the like).

[0069] In a preferred embodiment, the modified rosin resin (Al) comprises a rosin ester.

[0070] In one embodiment, the rosin ester comprises a rosin resin, a hydrogenated rosin resin, some other modified rosin resin esterified with glycerol, pentaerythritol, triethylene glycol, ethylene glycol, diethylene glycol, methanol, and / or maleic acid.

[0071] Exemplary rosin esters include, but are not limited to HARIESTER products available from Harima Chemicals, Inc.; a glycerol ester of hydrogenated rosin, such as STAYB ELITE ESTER 10-E and a pentaerythritol ester of gum rosin, such as PERMALYN 6110, each available from Eastman; a highly stabilized rosin ester, such as SUPER ESTER A-125, SUPER ESTER A-75, a polymerized rosin ester, such as PENSEL D-125, a hydrogenated rosin ester, such as PINECRYSTAL KE-100, a glycerol ester of hydrogenated rosin, such as PINECRYSTAL KE-311, and a pentaerythritol ester of hydrogenated rosin, such as PINECRYSTAL KE-359, each available from Arakawa Chemical Industries, Ltd.; a pentaerythritol ester of stabilized rosin, such as PINEREZ 2308 A and PINECLEAR 4306 A, a maleic modified rosin ester, such as FILTREZ 3305, each available from Lawter; a glycerol ester of hydrogenated wood rosin, such as FORAL 85, a pentaerythritol ester of hydrogenated rosin, such as FORAL 105, a methyl ester of hydrogenated rosin, such as HERCOLYN D, each available from DRT; a glycerol ester of partially dimerized rosin, such as PEXALYN ESTER 10, a glycerol ester of rosin, such as PEXALYN 9085, a pentaerythritol ester of stabilized rosin, such PEXALYN 9100, and a pentaerythritol ester of wood rosin that has been stabilized by hydrogenation, such as PENTALYN H, each available from Pinova, Inc.; and a functionalized rosin resin, for example an ester (e.g., glycerol ester) of a rosin which has been modified with maleic anhydride or a rosin which has been subject to carboxylic acid reduction conditions, with specific mention being made to LEWISOL 28-M, available from Synthomer.

[0072] Other exemplary modified rosin resins (Al) except the rosin esters, include but are not limited to a hydrogenated acidic rosin such as FORAL AX and FORAL DX, each available from Pinova; a partially hydrogenated acidic rosin such as STAYB ELITE RESIN-E available from Synthomer, and STAYB ELITE and STAYB ELITE A, each available from Pinova; a dimerized rosin such as POLY-PALE available from Synthomer; and ABITOL E hydroabietyl alcohol, available from Synthomer.

[0073] In one embodiment, the modified rosin resin (Al) comprises preferably at least one selected from the group consisting of a glycerol ester of a hydrogenated rosin, a glycerol esterified rosin, a pentaerythritol ester of a hydrogenated rosin, a pentaerythritol esterified rosin, a triethylene glycol esterified rosin, a maleic modified rosin ester, and a methyl esterified rosin. In a preferred embodiment, the modified rosin resin (Al) comprises a glycerol ester of a hydrogenated rosin.

[0074] In one embodiment, the rosin resin (A) comprises both modified rosin resin (Al) and unmodified rosin resin. For instance, the rosin resin (A) may comprise preferably at least 40 wt%, more preferably at least 60 wt%, even more preferably at least 70 wt%, even more preferably at least 80 wt%, even more preferably at least 90 wt%, even more preferably at least 95 wt%, even more preferably at least 99wt% modified rosin resin (Al) based on a total weight of the modified rosin resin (Al) and the unmodified rosin resin.

[0075] In one embodiment, the rosin resin (A) has hydroxyl value (OHV) of 40 mg KOH / g or less, preferably 38 mg KOH / g or less, more preferably 35 mg KOH / g or less, even more preferably 30 mg KOH / g or less, even more preferably 25mg KOH / g or less, even more preferably 20 mg KOH / g or less, even more preferably 15 mg KOH / g or less, even more preferably 10 mg KOH / g or less, and / or preferably greater than 1 mg KOH / g, more preferably greater than 5 mg KOH / g, even more preferably greater than 8 mg KOH / g. The hydroxyl value (OHV) is defined as the number of milligrams of potassium hydroxide required to neutralize the acetic acid taken up on acetylation of one gram of a chemical substance that contains free hydroxyl groups. The hydroxyl values can be determined according to Japanese Industrial Standards JIS K 0070: 1992 “Test methods for acid value, saponification value, ester value, iodine value, hydroxyl value, and unsaponifiable matter of chemical products.”

[0076] In one embodiment, the rosin resin (A) has an acid value (AV) of less than 22 mgKOH / g, preferably less than 20 mgKOH / g, more preferably less than 18 mgKOH / g, even more preferably less than 16 mgKOH / g, even more preferably less than 14 mgKOH / g, even more preferably less than 12 mgKOH / g, even more preferably less than 10 mgKOH / g, even more preferably less than 8 mgKOH / g, even more preferably less than 7 mgKOH / g, and / or preferably greater than 1 mgKOH / g, more preferably greater than 2 mgKOH / g, even more preferably greater than 3 mgKOH / g, even more preferably greater than 4 mgKOH / g, even more preferably greater than 5 mgKOH / g, or even more preferably greater than 6 mgKOH / g. In one embodiment, the rosin resin (A) has an acid value preferably in a range of 1 to 22 mgKOH / g, more preferably 2 to 20 mgKOH / g, even more preferably 3 to 18 mgKOH / g, even more preferably 4 to 16 mgKOH / g, even more preferably 5 to 14 mgKOH / g, or even more preferably 6 to 12 mgKOH / g. The acid value represents an amount (mg) of potassium hydroxide necessary for completely neutralizing 1 g of resin. The acid values can also be determined according to the aforementioned Japanese Industrial Standards JIS K 0070: 1992. Exemplary embodiments of rosin resins (A) having acid values of less than 22 mgKOH / g include but are not limited to PINECRYSTAL KE-311 (AV = 6 mgKOH / g, OHV = 9 mgKOH / g), a glycerol ester of hydrogenated rosin from Arakawa Chemical Industries, Ltd., and PINECLEAR 4306 A (AV = 18 mgKOH / g, OHV = 25 mgKOH / g), a rosin ester from Lawter.

[0077] The modified rosin resin (Al) having an acid value of less than 22 mgKOH / g and a hydroxyl value of 40 mg KOH / g or less been found to provide superior decap times while maintaining good dry times when used in combination with a cosolvent (B2) having a Hildebrand solubility parameter of less than 11 cal1 / 2cm3 2, and an alcohol (Bl). Without being bound by theory, it is believed that the modified rosin resin (Al) improves the decap behavior of the inkjet inks by forming a thin ‘skin’ or film covering within the printhead nozzles, thereby creating a temporary seal that prevents or reduces solvent loss during periods of inactivity, but where the ‘skin’ can be easily broken once the printing operation resumes.

[0078] (B) Solvent System

[0079] In many printing processes that utilize solvent-based inks, in particular thermal inkjet printing, the selection of an appropriate solvent system may impact the reliability of the printing process, the properties / appearance of the printed ink product, and the overall printing process efficiency. For example in thermal inkjet printing, the choice of solvent system may 1) aid bubble formation during the jetting process resulting in reliable ink jetting, 2) affect the stability / volatility of the inkjet inks by changing the interaction dynamics between the solvent(s) and the various inkjet ink components and thus the decap behavior, kogation, and / or drop trajectory, 3) impact the adhesion, rub and scratch resistance, and optical density properties of the printed image through the interactive forces between the solvent system and the other inkjet ink components even though the solvent(s) may no longer be present, or may be present in reduced amounts, after drying, 4) influence the drying time after application or the equipment needed to dry the applied ink, and / or 5) impact droplet dynamics. In light of the above, particular preference is given to inkjet inks with a solvent system (B) that includes an alcohol (Bl) and a cosolvent (B2) having a Hildebrand solubility parameter of less than 11 cal1 / 2cm3 2.

[0080] The alcohol (Bl) of the present disclosure means a compound in which one hydrogen atom of an alkyl group is substituted by one hydroxy group, that is, a compound having an alkyl group and a hydroxy group.

[0081] The amount of the alcohol (Bl) present in the inkjet ink may be at least 75 wt%, at least 76 wt%, and / or at most 92 wt%, at most 91 wt%, at most 90 wt%, at most 89 wt%, at most 88 wt%, at most 87 wt%, at most 86 wt%, at most 85 wt%, at most 84 wt%, at most 83 wt%, at most 82 wt%, at most 81 wt%, at most 80 wt%, based on a total weight of the inkjet ink. In one embodiment, the alcohol (Bl) is present preferably in an amount of 75 to 92 wt%, more preferably 76 to 88 wt%, or even more preferably 76 to 80 wt%, based on a total weight of the inkjet ink.

[0082] In one embodiment, the alcohol (Bl) may contain at least 1 carbon atom, preferably at least 2 carbon atoms, and up to 8 carbon atoms, preferably up to 6 carbon atoms, more preferably up to 5 carbon atoms, more preferably up to 4 carbon atoms, more preferably up to 3 carbon atoms. Preferred alcohols (Bl) are those which have a boiling point of less than 120 °C, preferably less than 110 °C, more preferably less than 100 °C, even more preferably less than 90 °C, yet even more preferably less than 85 °C.

[0083] In one embodiment, the alcohol (Bl) comprises at least one selected from the group consisting of methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-pentanol, 3- pentanol, and t-amyl alcohol. Preferably the alcohol (Bl) comprises at least one selected from the group consisting of methanol, ethanol, 1-propanol, and 2-propanol. In a preferred embodiment, the alcohol (Bl) comprises ethanol. The inclusion of the cosolvent (B2) may aid solvation of the inkjet ink components, provide polarity compatibility with the rosin resin (A) for desirable decap behavior, and provide the inkjet inks with acceptable volatility for the purposes of dry times. The preferable amount of cosolvent (B2) present in the inkjet ink may be at least 1 wt%, more preferably at least 1.5 wt%, even more preferably at least 2 wt%, even more preferably at least 2.5 wt% and / or at most 20 wt%, more preferably at most 15 wt%, even more preferably at most 12 wt%, even more preferably at most 10 wt% based on a total weight of the inkjet ink. In one embodiment, the cosolvent (B2) is present preferably in an amount of 1 to 20 wt%, more preferably 2 to 15 wt%, even more preferably 2.5 to 10 wt% based on a total weight of the inkjet ink.

[0084] The cosolvent (B2) has a Hildebrand solubility parameter of less than 11 cal1 / 2cm3 2, preferably less than 10.5 cal1 / 2cm3 2, and / or preferably greater than 7.5 cal1 / 2cm3 2, more preferably greater than 8 cal1 / 2cm3 2, even more preferably greater than 8.5 cal1 / 2cm3 2. In one embodiment, the cosolvent (B2) preferably has a Hildebrand solubility parameter in a range of 7.5 to 11 cal1 / 2cm3 2, more preferably 8 to 10.5 cal1 / 2cm3 2, or even more preferably 8.5 to 10.5 cal1 / 2cm3 2.

[0085] The Hildebrand solubility parameter (5) is a value tabulated for many different polymers and solvents and allows one to estimate miscibility. The Hildebrand solubility parameter (5) is shown in a unit of cal1 / 2cm3 2in this application. The Hildebrand solubility parameter provides a numerical estimate of the degree of interaction between materials, and can be a good indication of solubility, particularly for materials such as polymers. Materials with similar values of 5 are likely to be miscible. The Hildebrand solubility parameter is the square root of the cohesive energy density and may be calculated from the equation where A7 / „ is the enthalpy of vaporization of the solvent of interest, R is the gas constant, T is the temperature, and Vmis the molar volume of the solvent of interest. Solvents having a Hildebrand solubility parameter 5 of less than 11 cal1 / 2cm3 2at room temperature include, but are not limited to, ethylene glycol monobutyl ether acetate (5 = 8.90 cal1 / 2cm3 2), propylene glycol methyl ether acetate (8.90 cal1 / 2cm3 2), acetone (9.77 cal1 / 2cm3 2), cyclohexanone (10.40 cal1 / 2cm3 2), n-pentane (7.0 cal1 / 2cm3 2), n-hexane (7.24 cal1 / 2cm3 2), diethyl ether (7.62 cal1 / 2cm3 2), ethyl acetate (9.1 cal1 / 2cm3 2), chloroform (9.21 cal1 / 2cm3 2), dichloromethane (9.93 cal1 / 2cm3 2), methylethylketone (9.0 cal1 / 2cm3 2), and 1,3-dioxolane (8.6 cal1 / 2cm3 2).

[0086] In one embodiment the cosolvent (B2) is at least one selected from the group consisting of ethylene glycol monobutyl ether acetate (EB acetate), propylene glycol methyl ether acetate (PM acetate), acetone, and cyclohexanone. In a preferred embodiment the cosolvent (B2) comprises ethylene glycol monobutyl ether acetate.

[0087] In one embodiment, a weight ratio of the cosolvent (B2) to the rosin resin (A) ((B2):(A)) is preferably 1 : 1 to 10: 1, or more preferably 1.5: 1 to 8: 1, or even more preferably 2: 1 to 6: 1, or even more preferably 2: 1 to 5: 1.

[0088] In some embodiments, the inkjet inks are preferably substantially free of solvents having a boiling point higher than 255 °C, more preferably higher than 250 °C, even more preferably higher than 245 °C, even more preferably higher than 240 °C, even more preferably higher than 235 °C, even more preferably higher than 230 °C, even more preferably higher than 220 °C, even more preferably higher than 210 °C, even more preferably higher than 200 °C, or even more preferably higher than 195 °C.

[0089] In some embodiments, the inkjet inks of the present disclosure are preferably substantially non-aqueous, meaning that no water is added to the inkjet inks other than what may be incidental amounts of moisture derived from ambient conditions. For instance, an inkjet ink may comprise less than 1 wt%, less than 0.5 wt%, less than 0.1 wt%, less than 0.05 wt%, less than 0.01 wt% water, or may comprise 0 wt% water, based on a total weight of the inkjet ink.

[0090] (C) Colorant

[0091] Inkjet inks of the present disclosure preferably comprise colorants (C) to provide colored inks that may be used for a variety of printing purposes, and the inkjet inks are not limited to any particular color. In addition to providing color to the inkjet inks, such colorants (C) may be capable of improving the light resistance, the weather resistance, etc., of the printed images. Any colorant (C) may be employed in the inkjet inks to provide the desired color, including dyes, pigments, mixtures thereof, and the like, provided that the colorant (C) may be dissolved or dispersed within the inkjet inks. Suitable colors include, for example, cyan, magenta, yellow, and key (black) (“CMYK”), white, orange, green, light cyan, light magenta, violet, and the like, including both spot colors and process colors. The inkjet inks may be formulated with various dyes, with particular preference given to metal complex dyes.

[0092] In one embodiment, a metal complex dye used as a colorant (C) is further more a metal complex azo dye, which is a compound formed from a metal center and a ligand which comprises an azo functional group (also known as a diazenyl functional group). Typically, the ligand which comprises an azo functional group is a molecule which itself may be considered an azo dye.

[0093] This ligand which comprises an azo functional group is coordinated to a metal center, typically a transition metal or main-group metal or metalloid but not an alkali metal or alkaline earth metal. Examples of suitable metals which may form the metal center include, but are not limited to titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, zirconium, niobium, molybdenum, ruthenium, rhodium, cadmium, aluminum, indium, tin, bismuth, and mixtures thereof. Such coordination may be through any suitable functional group present on the ligand.

[0094] In preferred embodiments, the metal center is a chromium ion. In some embodiments, the chromium ion is in the +3 oxidation state. In such embodiments, the metal complex may have a positive charge, a negative charge, or have no charge. In embodiments in which the metal complex has a positive charge, the metal complex azo dye may further comprise any suitable anion for charge balance. Examples of such suitable anions include, but are not limited to carboxylates, halides, sulfates, phosphates, hydrogen phosphates, dihydrogen phosphates, nitrates, and mixtures thereof. In embodiments in which the metal complex has a negative charge, the metal complex azo dye may further comprise any suitable cation for charge balance. Examples of such suitable cations include, but are not limited to alkali metals, alkaline earth metals, ammonium compounds, and mixtures thereof.

[0095] Examples of suitable metal complex azo dyes include, but are not limited to Solvent Black 27, Solvent Black 28, Solvent Black 29, Solvent Black 34, Solvent Blue 137, Solvent Brown 37, Solvent Brown 42, Solvent Brown 43, Solvent Brown 52, Solvent Orange 54, Solvent Red 8, Solvent Red 109, Solvent Red 119, Solvent Red 122, Solvent Yellow 19, Solvent Yellow 21, Solvent Yellow 25, Solvent Yellow 79, Solvent Yellow 82, Solvent Yellow 88, Solvent Yellow 146, Solvent Violet 58, Solvent Violet 61, and Solvent Yellow 79.

[0096] Among them, more suitable examples include Solvent Black 27, Solvent Black 29, Solvent Yellow 79, and onium salts of Basic Red 1 and Acid Yellow 23. Commercial products of Solvent Black 27 include VALIFAST Black 3820, VALIFAST Black 3830, and VALIFAST Black 3840; and commercial products of Solvent Black 29 include VALIFAST Black 3808 and VALIFAST Black 3870. Commercial products of onium salt of Basic Red 1 and Acid Yellow 23 include VALIFAST Red 1355, and commercial products of Solvent Yellow 79 include VALIFAST YELLOW 3150 (all of these are available from Orient Chemical Industry Co., Ltd.). Among these, Solvent Black 27 is more preferable.

[0097] In some embodiments, the inkjet inks comprise a colorant (C) preferably at a concentration of at least 0.1 wt%, more preferably at least 0.5 wt%, even more preferably at least 1 wt%, even more preferably at least 1.5 wt%, even more preferably at least 2 wt%, even more preferably at least 2.5 wt%, even more preferably at least 3 wt%, even more preferably at least 3.5 wt%, even more preferably at least 4 wt%, even more preferably at least 4.5 wt%, even more preferably at least 5 wt%, even more preferably at least 5.5 wt%, even more preferably at least 6 wt%, even more preferably at least 6.5 wt%, even more preferably at least 7 wt%, and / or preferably at most 15 wt%, more preferably at most 14.5 wt%, even more preferably at most 14 wt%, even more preferably at most 13.5 wt%, even more preferably at most 13 wt%, even more preferably at most 12.5 wt%, even more preferably at most 12 wt%, even more preferably at most 11.5 wt%, even more preferably at most 11 wt%, even more preferably at most 10.5 wt%, even more preferably at most 10 wt%, based on a total weight of the inkjet ink. In one embodiment, the colorant (C) is present preferably in an amount of 0.1 to 15 wt%, more preferably 2 to 14 wt%, even more preferably 4 to 12 wt%, even more preferably 5 to 10 wt%, or even more preferably 6 to 8 wt%, based on a total weight of the inkjet ink.

[0098] (D) Silicone

[0099] In some embodiments, the inkjet inks preferably further comprise a silicone (D). The silicone (D) controls ink wettability, which contributes to improved image quality. The silicone (D) may act as a surfactant, providing anti-blocking, ink acceptance, levelling, anti- cratering, increased surface slip, and / or substrate wetting properties, among other benefits, without sacrificing inkjet ink decap performance.

[0100] As the silicone (D), amine modified silicone, polyether-modified silicone, carboxymodified silicone, alkyl-modified silicone, and aralkyl-modified silicone are preferable from the viewpoint of improving wettability, and amine modified silicone is preferable from the viewpoint of improving adhesion to the substrate.

[0101] In one embodiment, the silicone (D) is an amine modified silicone. The amine modified silicone may be a block copolymer having a pendent graft structure, which comprises or consists of (i) a silicone backbone (main chain) and (ii) one or more organoamine side chains attached to the silicone backbone, and optionally (iii) one or more fatty alkyl side chains attached to the silicone backbone. Therefore, as long as at least one organoamine side chain is attached to a silicone backbone, the material meets the definition of an “amine modified silicone” regardless of whether additional side chain types (e.g., fatty alkyl side chains) are also attached to the silicone backbone. Preferably, no other side chains, besides the organoamine side chain(s) and optionally the fatty alkyl side chain(s) are present in the amine modified silicone.

[0102] As referred to herein, “side chains” are not continuations of the silicone backbone — as would be the case in linear block copolymers, for example of A-B-A structure — but instead are attached to the silicone backbone (main chain) as pendent grafts thereby forming a branching point on the silicone backbone with the side chains extending from the silicone backbone via covalent bonds. Preferred organoamine modified silicones are those which are non-hydrolyzable, that is, where the side chains are attached to the silicone backbone via Si-C bonds.

[0103] <(i) Silicone backbone> The silicone backbone may be based on any organosilicon polymer or oligomer (polyorganosiloxane) of linear or branched structure, of variable molecular weight, which can be formed from polymerization and / or polycondensation of suitably functionalized silanes, and which has a polysiloxane backbone structure (silicon atoms are linked together via oxygen atoms, — Si — O — Si — ), with alkyl, aryl, and / or arylalkyl groups directly bonded to the (tetravalent) silicon atoms. For example, the polyorganosiloxane backbone may be a linear structure including, but not limited to, a polydimethylsiloxane (dimethicone) backbone (where each silicon atom in the backbone is directly bonded to two methyl groups), a poly(dimethylsiloxane-co-methylphenylsiloxane) backbone, a poly(dimethylsiloxane-co- diphenylsiloxane) backbone, and a poly(dimethylsiloxane-co-methylalkylsiloxane) backbone; or a branched structure with specific mention being made to a polydimethylsiloxy ethyl dimethicone.

[0104] <(ii) Organoamine side chain>

[0105] The amine modified silicone contains at least one organoamine side chain, which is based on an organic amine or amine-containing polymer such as a polyaziridine, for example those formed from ring opening polymerization of one or more alkylene imines, with ethylene imine (aziridine), and propylene imine being the most preferred, including copolymers such as block copolymers thereof. Preferably, the organoamine side chain is an alkylamine, an arylamine, an arylalkylamine, a fatty amine, or a polyaziridine which extends from the silicone backbone.

[0106] The organoamine side chain may comprise a primary amine, a secondary amine, a tertiary amine, or a combination of these. Such amines may be present in any suitable number, for example from 1 to 1,000. In some embodiments, the preferable organoamine side chain is selected from the group consisting of a monoamine comprising a primary amine and a diamine comprising a primary amine and a secondary amine. Such a monoamine may be an alkylamine, an arylamine, an arylalkylamine, or a fatty amine. Such a diamine may be an alkylamine, an arylamine, an arylalkylamine, a or a fatty amine.

[0107] <(iii) Fatty alkyl side chain>

[0108] The amine modified silicone may optionally also be modified with one or more fatty alkyl side chains, such as those containing at least 8 carbon atoms, preferably at least 10 carbon atoms, more preferably at least 12 carbon atoms, and up to 22 carbon atoms, preferably up to 20 carbon atoms, more preferably up to 18 carbon atoms, even more preferably up to 16 carbon atoms, yet even more preferably up to 14 carbon atoms. Exemplary fatty alkyl side chain groups include, but are not limited to, capryl, nonyl, decyl, undecyl, lauryl, tridecyl, myristyl, pentadecyl, cetyl, palmitoleyl, heptadecyl, stearyl, oleyl, arachidyl, and behenyl, with specific mention being made to lauryl, myristyl, cetyl, and stearyl, preferably lauryl.

[0109] <(iv) Polyether side chain>

[0110] The amine modified silicone may optionally also be modified with one or more polyether side chains. The polyether side chain may be based on a polyalkylene glycol oligomer or polymer, for example those formed from ring opening polymerization of one or more alkylene oxides, with ethylene oxide (EO), propylene oxide (PO), and / or butylene oxide (BO) being the most preferred, including copolymers such as block copolymers thereof. Preferably, the polyether side chain is a polyethylene glycol or a polyethylene glycolpolypropylene glycol copolymer which extends from the silicone backbone, more preferably the polyether side chain is a polyethylene glycol side chain formed from only ethylene oxide, EO.

[0111] Various lengths of polyether side chain(s) may be utilized — typically, the number of moles of alkylene oxide units per side chain ranges from at least 2, preferably at least 3, more preferably at least 4, even more preferably at least 5, yet even more preferably at least 6, and up to 50, preferably up to 40, preferably up to 30, preferably up to 20, preferably up to 15, more preferably up to 12, even more preferably up to 10, yet even more preferably up to 9, with particular preference given to 3 to 10 moles, preferably 4 to 9 moles of ethylene oxide (EO) units per side chain.

[0112] Moreover, any polyether side chain present may be uncapped (whereby the end of the polyether side chain opposite of the silicone backbone terminates in -H, forming a terminal hydroxyl functional group) or may be capped with an alkyl group having 1, 2, 3, or 4 carbon atoms (forming a terminal alkyl ether group), with specific mention being made to methyl, ethyl, propyl, and butyl.

[0113] In some embodiments, the amine modified silicone is a block copolymer having a pendent graft structure, for example as represented by formula (I- A) where: o is 0 or a positive integer, for example at least 1, preferably at least 2, more preferably at least 3, even more preferably at least 4, yet even more preferably at least 5, and up to 500, preferably up to 400, preferably up to 300, more preferably up to 200, even more preferably up to 100, yet even more preferably up to 50; p represents the number of constitutional units containing the organoamine side chain, and is a positive integer, for example at least 1, preferably at least 2, more preferably at least 3, even more preferably at least 4, yet even more preferably at least 5, and up to 100, preferably up to 80, preferably up to 60, more preferably up to 40, even more preferably up to 20, yet even more preferably up to 10; and

[0114] A is an amine containing group (organoamine) as described above. In some embodiments, the preferable amine modified silicone is a block copolymer having a pendent graft structure, having a structure of diamine comprising a primary amine and a secondary amine, for example as represented by formula (I-B).

[0115] The preferable amine modified silicones which have the above structure are KF-859,

[0116] KF-393, KF-860, KF-880, KF-8004, KF-8002, KF-8005, KF-867, KF-8021, KF-869, and KF-861, each available from Shin-Etsu Chemical Co.

[0117] The amine modified silicone having a pendent graft structure is formed from a linear polydimethylsiloxane backbone containing one or more organoamine side chains.

[0118] In some embodiments, the amine modified silicone is a block copolymer having a pendent graft structure and, optionally, one or more fatty alkyl side chains or polyether side chains as described above. In some embodiments, the amine modified silicone is a block copolymer having a pendent graft structure, wherein the pendant graft structure has a branched polydimethylsiloxane backbone containing one or more organoamine side chains and, optionally, one or more fatty alkyl side chains or polyether side chains as described above.

[0119] In some embodiments, the inkjet ink is substantially free of silicones devoid of an amine functionalization. Examples of such silicones include unmodified silicones (e.g., ones which do not have a side chain containing a non-siloxane functional group) and modified silicones having only other, non-amine functional groups, such as polyether modified silicones (e.g., ones having only a polyether side chain), mercapto modified silicones, vinyl modified silicones, silanol modified silicones, hydride modified silicones, epoxy modified silicones, (meth)acrylate modified silicones, carboxylate modified silicones, and haloalkyl modified silicones. In some embodiments, the inkjet ink is devoid of silicones devoid of an amine functionalization. That is, the inkjet ink does not contain a silicone which does not have an amine functionalization. In such embodiments, the amine modified silicone is the only silicone present in the inkjet ink. In some embodiments in which the inkjet ink is devoid of silicones devoid of an amine functionalization, the amine modified silicone may contain or comprise other functional groups, such as the ones listed above. In some embodiments in which the inkjet ink is devoid of silicones devoid of an amine functionalization, the amine modified silicone does not contain or comprise other functional groups. That is, the inkjet ink is devoid of silicones which do not have an amine functionalization and the amine modified silicone(s) present are devoid of non-amine functional groups.

[0120] In some embodiments, the silicone (D) preferably has a viscosity measured at 25 °C of at least 25 mm2 / s, preferably at least 30 mm2 / s, preferably at least 35 mm2 / s, preferably at least 40 mm2 / s, preferably at least 45 mm2 / s, preferably at least 50 mm2 / s, preferably at least 55 mm2 / s, preferably at least 60 mm2 / s and up to 250 mm2 / s, preferably up to 240 mm2 / s, preferably up to 230 mm2 / s, preferably up to 220 mm2 / s, preferably up to 210 mm2 / s, preferably up to 200 mm2 / s, preferably up to 190 mm2 / s, preferably up to 180 mm2 / s, preferably up to 170 mm2 / s, preferably up to 160 mm2 / s, preferably up to 150 mm2 / s, preferably up to 140 mm2 / s, preferably up to 130 mm2 / s, preferably up to 120 mm2 / s, preferably up to 110 mm2 / s.

[0121] In some embodiments, the silicone (D) preferably has an amine functional group equivalent weight (FGEW) of 350 to 11,000 g / mol, preferably 1,000 to 9,000 g / mol, preferably 1,500 to 8,800 g / mol, preferably 1,700 to 7,600 g / mol, preferably 2,000 to 7,000 g / mol, preferably 3,000 to 6,500 g / mol, preferably 5,000 to 6,000 g / mol. The functional group equivalent weight refers to the weight of amine modified silicone that contains one formula-weight of the amine functional group.

[0122] Suitable examples of the amine modified silicone which may be employed in the disclosed inkjet inks include, but are not limited to, KF-865 (mono amino, viscosity 110mm2 / s at 25°C, functional group equivalent weight (FGEW) = 5,000), KF-868 (mono amino, viscosity 90mm2 / s at 25°C, FGEW = 8,800), KF-864 (mono amino, viscosity l,700mm2 / s at 25°C, FGEW = 3,800), KF-859 (diamino, viscosity 60mm2 / s at 25°C, FGEW = 6,000), KF-393 (diamino, viscosity 70mm2 / s at 25°C, FGEW = 350), KF-860 (diamino, viscosity 250mm2 / s at 25°C, FGEW = 7,600), KF-880 (diamino, viscosity 650mm2 / s at 25°C, FGEW = 1,800), KF-8004 (diamino, viscosity 800mm2 / s at 25°C, FGEW = 1,500), KF-8002 (diamino, viscosity l,100mm2 / s at 25°C, FGEW = 1,700), KF-8005 (diamino, viscosity l,200mm2 / s at 25°C, FGEW = 11,000), KF-867 (diamino, viscosity 1300mm2 / s at 25°C, FGEW = 1,700), KF-8021 (diamino, viscosity 15,000mm2 / s at 25°C, FGEW = 55,000), KF- 869 (diamino, viscosity l,500mm2 / s at 25°C, FGEW = 3,800), and KF-861 (diamino, viscosity 3,500mm2 / s at 25°C, FGEW = 2,000), each available from Shin-Etsu Chemical Co. In a preferred embodiment, the amine modified silicone is KF-859.

[0123] The silicone (D) may be present preferably in the inkjet ink in an amount of at least 0.001 wt%, more preferably at least 0.01 wt%, even more preferably at least 0.05 wt%, even more preferably at least 0.1 wt%, at least 0.2 wt%, at least 0.5 wt%, and / or preferably at most 4 wt%, preferably at most 3.5 wt%, even more preferably at most 3 wt%, even more preferably at most 2.5 wt%, even more preferably at most 2 wt%, even more preferably at most 1.5 wt%, even more preferably at most 1 wt%, based on a total weight of the inkjet ink. In one embodiment, the silicone (D) may preferably be present in an amount of 0.001 wt% to 4 wt%, more preferably, 0.05 to 3 wt%, even more preferably 0.1 to 2.5 wt%, even more preferably 0.2 to 2 wt%, or even more preferably 0.5 to 1.5 wt%, even more preferably 0.5 to 1 wt% based on a total weight of the inkjet ink.

[0124] (E) pH adjuster

[0125] In some embodiments, the inkjet inks further comprise pH adjuster (E). The pH adjuster achieves higher ink stability and improved finish of printing (higher quality of colorformation) by improving solubility of dye.

[0126] In a preferred embodiment, the pH adjuster (E) comprises an amine. As the amine, alkyl amine, alkoxyalkyl amine, diamine, polyamine, and alkanolamine are preferable. Among these, alkanolamine is more preferable from the viewpoint of increasing the solubility of the dye in alcohol.

[0127] Alkanolamines are alkane-based compounds that contain both hydroxyl (-OH) and amine (primary, secondary, or tertiary) groups. In some embodiments, the alkanolamine has a total of at least 2 carbon atoms, at least 3 carbon atoms, at least 4 carbon atoms, and / or up to 8 carbon atoms, up to 7 carbon atoms, up to 6 carbon atoms, or up to 5 carbon atoms. In a preferred embodiment the alkanolamine has 3 carbon atoms.

[0128] In preferable embodiments, the alkanolamine used in the inkjet inks herein has the following general formula IE where X, Y, and Z are independently selected from the group consisting of a hydrogen; a Ci-C5alkyl group, preferably a C2-C3alkyl group; and an alkanol group, preferably a C2-C5alkanol group, more preferably a C3-C4alkanol group; and at least one of X, Y, and Z is an alkanol group (an alkyl substituent that bears at least one hydroxyl group). In some embodiments, one of X, Y, and Z is an alkanol group. In some embodiments, two of X, Y, and Z are an alkanol group. In some embodiments, X, Y, and Z are all alkanol groups.

[0129] With respect to the one or more alkanol groups, the alkyl chain thereof may contain branching. Alternatively, the alkyl chain of the alkanol group may be linear (contains no alkyl branching). In preferred embodiments, the alkanol group(s) is based on a linear alkyl chain. Further, the hydroxyl bearing carbon of the alkanol group may be a primary, secondary, or tertiary carbon, preferably the hydroxyl bearing carbon is a primary or secondary carbon.

[0130] The alkanolamine may contain a primary amine group (i.e., two of X, Y, and Z are hydrogen), a secondary amine group (i.e., one of X, Y, and Z are hydrogen), or a tertiary amine group (i.e., X, Y, and Z are all non-hydrogen). When an alkanolamine is employed that contains a secondary amine group, the two non-hydrogen substituents may be the same or different alkanol groups, preferably the same alkanol group, for example as is the case in diethanolamine. When an alkanolamine is employed that contains a tertiary amine group, the three non-hydrogen substituents may be the same or different alkanol groups, preferably the same alkanol group, for example as is the case in triethanolamine.

[0131] Suitable examples of the alkanolamine include, but are not limited to, isopropanolamine, ethanolamine, N-methylethanolamine, N,N-dimethylethanolamine, N- ethylethanolamine, N-propylethanolamine, N-isopropylethanolamine, N,N- diisopropylethanolamine, N-butylethanolamine, diethanolamine, N-methyldiethanolamine, N-ethyldi ethanolamine, triethanolamine, propanolamine (3 -Amino- 1 -propanol), N- methylpropanolamine, N,N-dimethylpropanolamine, dipropanolamine, tripropanolamine, N,N-dimethylisopropanolamine, diisopropanolamine, triisopropanolamine, 2-amino-2- methyl-1 -propanol, 2-amino-2-ethyl-l,3-propanediol, 4-amino-l -butanol, 2-amino-l -butanol, sec-butanolamine, and di-sec-butanolamine including the various stereoisomers thereof, as well as mixtures thereof. In preferred embodiments, the alkanolamine comprises at least one selected from the group consisting of isopropanolamine, ethanolamine, propanolamine (3- amino-1 -propanol), diethanolamine, and triethanolamine. In a preferred embodiment, the alkanolamine comprises isopropanolamine (l-amino-2-propanol).

[0132] In some embodiments, the pH adjuster (E) is present in the inkjet ink preferably in an amount of at least 0.1 wt%, more preferably at least 0.2 wt%, even more preferably at least 0.4 wt%, even more preferably at least 0.5 wt%, even more preferably at least 0.6 wt%, even more preferably at least 0.7 wt%, even more preferably at least 0.8 wt% and / or preferably at most 5 wt%, more preferably at most 4.5 wt%, even more preferably at most 4 wt%, even more preferably at most 3.5 wt%, even more preferably at most 3 wt%, even more preferably at most 2.5 wt%, even more preferably at most 2 wt%, even more preferably at most 1.5 wt%, based on the total weight of the inkjet ink. In one embodiment, the pH adjuster (E) is present in the inkjet ink in an amount preferably in a range of 0.1 to 5 wt%, more preferably 0.2 to 4 wt%, even more preferably 0.5 to 2 wt%, even more preferably 0.8 to 1.5 wt%, based on a total weight of the inkjet ink. In some embodiments, the weight ratio of the rosin resin (A) to the pH adjuster (E) ((A):(E)) is preferably in a range of 1 : 1 to 10: 1, more preferably 1.2: 1 to 6: 1, even more preferably 2: 1 to 5: 1, or even more preferably 2.2: 1 to 5: 1 even more preferably 2.5: 1 to 5: 1.

[0133] (F) Additive

[0134] In some embodiment, the inkjet inks may comprise one or more additional ingredients or additives. Such additional resins, binders, tackifiers, or adhesive substances may include, but are not limited to:

[0135] - terpene resins, e.g. a resin based on monoterpene monomer units, for example the monoterpene may be a linear monoterpene (e.g., myrcene, ocimene, etc.), a monocyclic monoterpenes (e.g., limonene, y-terpinene, a-phellandrene, P- phellandrene, terpinolene, etc.), or a bicyclic monoterpene (e.g., 3-carene, a-pinene, P-pinene, a-fenchene, camphene, etc.), including the various stereoisomers thereof, as well as mixtures thereof. Examples of terpene resins include but are not limited to PICCOLYTE Al 15, PICCOLYTE A125, PICCOLYTE A135, PICCOLYTE A135 PLUS, PICCOLYTE AO PLUS, PICCOLYTE A25, and PINOVA RESIN 2495, each being made from high purity a-pinene, as well as PICCOLYTE S25 (made from high purity P-pinene), each available from Pinova;

[0136] - terpene phenol resins, which have the structural units of a terpen and a phenol. The terpene phenol resins are copolymeric reaction products from alkylation of one or more phenolic compounds with one or more terpenes. Terpene phenol resins include, but are not limited to, YS POLYSTER products such as YS POLYSTER U130, YS POLYSTER U115, YS POLYSTER T160, and YS POLYSTER T145, available from Yasuhara Chemical Co. Ltd., and DERTOPHENE products such as DERTOPHENE T, DERTOPHENE T105, DERTOPHENE T115, and DERTOPHENE T160, available from DRT; other phenol resins (i.e. copolymers of phenolic compounds with formaldehyde), for example novolak resins such as PHENOLITE TD-2131 and PHENOLITE TD-2090 available from DIC Corp.; polyamide resins, for example VERSAMID 725, 744, 756, 759 available from BASF Japan Ltd., TOHMIDE 90, 92, 394-N available from Sanho Chemical Co. Ltd., and SUNMIDE 550, 554, 615A, 638, 640 available from Evonik; epoxy resins including sulfonamide-modified epoxy resins for example AD-PRO MTS available from Rit-Chem; (meth)acrylate and sty rene / (meth)acry late resins for example JONCRYL 63, JONCRYL 67, JONCRYL 586, JONCRYL 611, JONCRYL 680, JONCRYL 682, JONCRYL 693, available from BASF; PARALOID DM-55 and PARALOID B-66, available from Palmer Holland; PARALOID B-72, available from Dow Chemical, USA; and ELVACITE 2013, available from Lucite Inc.; polyurethane resins, such as those formed from reaction between (i) polyols including, but not limited to, ethylene glycol, propylene glycol, propanediol, butanediol, polyethylene glycol, polypropylene glycol, polytetrahydrofuran diol, 3- methyl-l,5-pentanediol, 1,9-nonanediol, polyester polyols such as polyethylene glycol adipate diol, polyethylene glycol succinate diol, poly(3-methyl-l,5-pentanediol adipate) glycol, poly(3-methyl-l,5-pentanediol terephthalate) glycol, carbonate polyols, and (ii) diisocyanates including, but not limited to, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4-diphenylmethane diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate; for example PERMAX 200, PERMAX 202, and SANCURE 20025F, available from Lubrizol; polyvinyl butyral resins, for example PIOLOFORM BN 16 and MOWITAL B20H available from Kuraray America, Inc.; polyhydroxystyrene resins such as poly(p-hydroxy styrene) from DuPont; vinyl resins, for example UCAR VYHH, VMCH, VMCA, and VAGF, available from Dow Chemical Company, and VINNOL E15 / 45, H14 / 36, E15 / 45M, and E16 / 40A, available from Wacker Chemie AG, Germany; formaldehyde resins, including sulfonamide modified formaldehyde resins such as p- toluene sulfonamide formaldehyde resin, melamine formaldehyde resins, sulfonamide-modified melamine formaldehyde resins; cellulose ester resins such as cellulose acetate butyrate (CAB-551-0.01) available from Eastman; opacifying agents, examples of which may include, but are not limited to, titanium dioxide, zirconium silicate, zirconium oxide, tin oxide, cerium oxide, zinc oxide, aluminum oxide, silica, kaolin, calcium carbonate, magnesium carbonate, calcium magnesium carbonate, barium carbonate, sodium feldspar, potassium feldspar, nepheline, calcium silicate, mullite, wollastonite, and talc; ketone solvents including, but not limited to, acetone, methyl ethyl ketone (MEK), 3- pentanone, methyl n-propyl ketone, methyl isopropyl ketone, ethyl isopropyl ketone, and methyl isobutyl ketone; glycol ethers, for instance ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono-isopropyl ether, ethylene glycol mono-n- propyl ether, ethylene glycol mono-t-butyl ether, ethylene glycol monobutyl ether, ethylene glycol mono-isobutyl ether, diethylene glycol monomethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono- t-butyl ether, propylene glycol mono-n-propyl ether, propylene glycol mono-isopropyl ether, propylene glycol mono-n-butyl ether, dipropylene glycol monomethyl ether, ethylene glycol mono-n-butyl ether acetate, propylene glycol methyl ether acetate, diethylene glycol mono-n-butyl ether acetate, diethylene glycol monoethyl ether acetate, ethylene glycol dimethylether, diethylene glycol dimethylether, diethylene glycol methyl ethyl ether, diethylene glycol diethylether, dipropylene glycol dimethyl ether, dipropylene glycol mono-n-propyl ether, as well as mixtures thereof; polyesters, sulfonated polyesters, gums, cellulose ethers, cellulose nitrate resins, polymaleic anhydrides, acetal polymers, styrene / butadiene copolymers, ketonealdehyde resins, and polyketone resins; an anti-kogation agent, a stabilizer, a humectant, a security taggant, some other resin, binder, tackifier, adhesive substance, rust inhibitor, or other inkjet ink additive(s) known by those of ordinary skill in the art; and the like, including mixtures thereof.

[0137] In one embodiment, the additive (F) may comprise a surfactant in addition to or instead of the amine modified silicone (D). Example surfactants, include, but are not limited to, polysiloxanes including organomodified silicones (e.g., alkyl, aryl, and / or arylalkyl modified silicones) except the amine modified silicone (D) such as SIL TECH C-32, available from Siltech Corporation, COATOSIL 1211C and 3573, each available from Momentive, KF-410 (an arylalkyl-modified poly dimethylsiloxane), available from Shin-Etsu Chemical Co., and BYK-322 and BYK-323 (arylalkyl-modified poly(dimethylsiloxane-co-methylalkylsiloxane)), each available from BYK Additives & Instruments; silicone acrylate copolymers such as KP-541, KP-543, KP-545, KP-550, and KP-575 (acrylic polymers grafted with polydimethylsiloxane side chains, available from Shin- Etsu Chemical Co., Ltd.), and BYK-3550 (available from BYK Japan K.K.); polyether modified silicones, including those which are block copolymers having a pendent graft structure formed from a linear or branched poly dimethyl siloxane backbone containing one or more polyether side chains and optionally one or more fatty alkyl side chains. Polyether modified silicones include but are not limited to KF- 6013 (PEG-9 dimethicone, uncapped, HLB = 10.0), KF-6015 (PEG-3 dimethicone, uncapped, HLB = 4.5), KF-6017 (PEG-10 dimethicone, uncapped, HLB = 4.5), and KF-6038 (lauryl PEG-9 polydimethylsiloxyethyl dimethicone, uncapped, HLB = 3.0), each available from Shin-Etsu Chemical Co., and BYK-307 (polyether modified polydimethylsiloxane), available from BYK Additives & Instruments;

[0138] - fluoropolymers such as FC-4430 and FC-4432, available from 3M Corporation;

[0139] - photo-cross-linkable silicone acrylates or silicone polyether acrylates such as TEGO

[0140] RAD 2100, TEGO RAD 2200, TEGO RAD 2250, TEGO RAD 2300 (silicone poly ether acrylate), each available from Evonik Industries, and BYK-UV 3500 and 3530, available from BYK; polyacrylates including polyacrylate copolymers and cross-polymers such as BYK-

[0141] 381 and BYK-361N (polyacrylate copolymer), each available from BYK, PEMULEN EZ-4U (acrylate / C10-C30 alkyl acrylate crosspolymer) and PEMULEN TR-2 (acrylic acid / C10-C30 alkyl acrylate crosspolymer), each available from Lubrizol; acetylenic diol and acetylenic glycol-based gemini surfactants such as SURFYNOL SEF and DYNOL surfactants, available from Evonik Industries; poly siloxane-based gemini surfactants such as TEGO TWIN 4100, available from Evonik Industries; non-ionic polyethers for example as substrate wetting surfactants such as TEGO WET

[0142] 510 (hydrophilic poly ether substrate wetting surfactant), available from Evonik Industries; amides or monoalkanolamides of fatty acids, including alkoxylated monoalkanolamides of fatty acids such as coconut fatty acid monoethanolamide and coconut fatty acid monoethanolamide reacted with 2-20 moles of ethylene oxide; ethers, such as alkoxylated C1-C22 alcohols including alkoxylated fatty alcohols such as BIO-SOFT N-600 (C12-C13 alcohol ethoxylate), MAKON DA-4 (ethoxylated isodecyl alcohol), MERPOL SE (alcohol ethoxylate), and POLYSTEP TD-6

[0143] (ethoxylated tridecyl alcohol), each available from Stepan, ethylene oxide / propylene oxide copolymers, alkoxylated alkylphenols, and alkyl polyglycosides (APGs) such as those made from reaction between fatty alcohols and glucose; fatty esters such as ethoxylated and / or propoxylated fatty acids (e.g., castor oil with 2 to 40 moles of ethylene oxide), alkoxylated glycerides (e.g., PEG-24 glyceryl monostearate), glycol esters and derivatives, monoglycerides, polyglyceryl esters, esters of polyalcohols, and sorbitan / sorbitol esters like sorbitan monolaurate (e.g., EMASOL L-10V, available from Kao) and polysorbates including mono-, bi- or trifatty acid esterified polysorbates such as TOXIMUL SEE-340 (sorbitan trioleate ethoxylate (20)), available from Stepan; and

[0144] - glycosides of fatty alcohols such as PLANTASENS NATURAL EMULSIFIER HE20 (cetearyl glucoside, sorbitan olivate), available from Clariant.

[0145] An additive in any of the above list, including surfactants, may be present in any of the inkjet inks of the present disclosure at a concentration of at least 0.0001 wt%, at least 0.0005 wt%, at least 0.001 wt%, at least 0.005 wt%, at least 0.01 wt%, at least 0.05 wt%, at least 0.1 wt%, at least 0.2 wt%, at least 0.4 wt%, at least 0.5 wt%, at least 0.7 wt%, at least 1 wt%, at least 1.2 wt%, at least 1.5 wt%, at least 1.7 wt%, at least 2 wt%, and / or at most 10 wt%, at most 9 wt%, at most 8 wt%, at most 7 wt%, at most 6 wt%, at most 5 wt%, at most 4.5 wt%, at most 4 wt%, at most 3.5 wt%, at most 3 wt%, based on a total weight of the inkjet ink.

[0146] Alternatively, the inkjet ink may be free of or substantially free of an additive or compound in any of the above list, including surfactants, meaning that such additive or compound has a concentration in the inkjet ink of less than 1 wt%, less than 0.5 wt%, less than 0.1 wt%, less than 0.05 wt%, less than 0.001 wt%, less than 0.0001 wt%, less than 0.00001 wt%, or 0 wt%. In some embodiments, the inkjet ink is preferably substantially free of terpene resins. In some embodiments, the inkjet ink is preferably substantially free of phenol resins. In some embodiments, the inkjet ink is preferably substantially free of terpene phenol resins. In alternative embodiments, the inkjet ink is substantially free of the colorant (C), the amine modified silicone (D), a surfactant, and / or the pH adjuster (E). In one embodiment, the inkjet ink is substantially free of a solvent having a Hildebrand solubility parameter of equal to or greater than 11 cal1 / 2cm3 2. In one embodiment, the inkjet ink is substantially free of rosin resin and modified rosin resin having an acid value of equal to or greater than 22 mgKOH / g and / or a hydroxyl value of greater than 40 mg KOH / g.

[0147] Methods of Making

[0148] Embodiments of the inkjet inks described herein may be prepared by any suitable technique known to those of ordinary skill in the art, for example by combining a rosin resin (A) or modified rosin resin (Al), and any desired optional ingredients (e.g., a colorant (C), an amine modified silicone (D), pH adjuster (E), and / or an additive (F)) with a suitable solvent system (B) comprising an alcohol (Bl) and a cosolvent (B2), in any order and stirring, agitating, and / or homogenizing at a temperature between 20 and 100°C for a suitable amount of time to form a homogeneous solution.

[0149] In one example, the inkjet ink may be made by first combining the rosin resin (A) with an alcohol (Bl) and a cosolvent (B2), and any optional resins, solvents, surfactants, or other additives in a vessel, followed by stirring for at least 10 minutes. The colorant (C) may then be added as the final component with continued mixing, and the solution may then be mixed for at least 10 minutes to afford the inkjet ink. The resulting inkjet ink may then be placed into a printing cartridge, such as e.g., a HP45Si printer cartridge made by Hewlett Packard, a FUNAI TIJ cartridge made by Funai Co., or some other printhead suitable for solvent-based ink.

[0150] Properties

[0151] The inkjet inks disclosed herein possess extended decap times at a range of temperatures and humidities, for example as measured by printing, exposing the inkjet ink to air (decapping the ink cartridge) for a particular time (e.g., 1 minute, 10 minutes, 30 minutes, 60 minutes, etc.), reprinting the same image, and then comparing the reprinted image after decapping to the original image to determine if loss of lines / loss of line clarity occurs in the narrow line image. If no loss of lines or loss of clarity occurs at the tested time interval, then the inkjet inks are given a “Good” decap rating for that time interval. If 1 to 10 lines are lost, or there is reduced clarity at the tested time interval, but not enough to significantly affect the clarity or readability of the image, then the inkjet inks are given an “Acceptable” decap rating for that time interval. If more than 10 lines are lost or the clarity and / or readability is substantially reduced at the tested time interval, then the inkjet ink is classified as “Not Good” at that time interval. Suitable inkjet inks are those which achieve an “Acceptable” or “Good” decap classification when decapped (i.e., exposed to air) for 30 seconds or longer, preferably 1 minute or longer, more preferably 10 minutes or longer, even more preferably 30 minutes or longer, yet even more preferably 60 minutes or longer. An inkjet ink that has “Acceptable” or “Good” decap classification at longer times is considered to have good “intermittent printability.”

[0152] The inkjet inks disclosed herein may also be characterized by a long running stability (also known as ink longevity or print longevity). To test the inkjet inks for running stability, a narrow line image (e.g., barcode) (1 mm x 1 cm, narrow lines, monochrome bitmap) may be printed uninterrupted for a consecutive number of pages (e.g., printed on 3,000 pages in a continuous printing operation), and the print quality may be assessed throughout the printing operation by visually inspecting certain pages (e.g., the 1,000th, 2,000th, and 3,000thpage) for missing nozzles. If no loss of lines / loss of line clarity occur in the page being inspected, then the inkjet ink is given a “G” (Good) running stability rating for that page. If 1-2 lines are lost / lost clarity in the page being inspected, but not enough to significantly affect the clarity or readability of the narrow line image, then the inkjet ink is given an “A” (Acceptable) running stability rating for that page. If more than 2 lines are lost / lost clarity in the page being inspected, then the inkjet ink is given an “NG” (Not Good) running stability rating for that print. Inkjet inks which maintain a “G” or “A” rating, preferably a “G” rating, when printed for at least 100 pages, preferably at least 500 pages, preferably at least 1,000 pages, preferably at least 1,500 pages, preferably at least 2,000 pages, preferably at least 2,500 pages, preferably at least 3,000 pages, preferably at least 3,500 pages, preferably at least 4,000 pages, preferably at least 4,500 pages, preferably at least 5,000 pages, are considered desirable in terms of running stability (ability to remain dispersed / suspended without settling / sedimentation and improper jetting).

[0153] Printed Article

[0154] The printed article of this invention comprises a substrate and a dried form of the inkjet ink of this invention disposed on the substrate.

[0155] The inkjet inks can be printed on various substrates including three-dimensional parts as well as flat sheets or webs that are supplied in roll form, for the manufacture of a wide variety of printed articles. While flat substrates are suitable substrates for forming printed articles, a particular advantage of the present disclosure is that the disclosed inkjet inks — having long throw distance capabilities — enable printed images to be formed on complex three-dimensional substrates, such as those which are radial, curved, serrated, corrugated, fluted, lipped, and / or those which have a structured surface (e.g., grained surface), all of which are notoriously difficult substrates owing to the long distance that the ink must travel to reach all parts of the complex surface. The printed articles may be suitable in the graphic arts, textiles, packaging (e.g., food packaging, pharmaceutical packaging, etc.), lottery, direct mail, business forms and publishing industries, examples of which include a tag or label, a lottery ticket, a publication, packaging (e.g., food packaging, pharmaceutical packaging, blister packaging, other various flexible packing, etc.), a folding carton, a rigid container (e.g., a plastic cup or tub, glass containers, metal cans, bottles such as PET bottles, jars, and tubes), envelopes, corrugate, a point-of-sale display, and the like. Particularly preferred printed articles are those having a dried form of the inkjet ink disposed on a complex three- dimensional part of the printed article, for example, where the printed image is located on a fluted or corrugated portion of a plastic container, or on the concave dome-shaped bottom of a metal can.

[0156] The inkjet inks may be printed on porous (or penetrable) substrates, examples of which include, but are not limited to, non-coated paper, wood, membranes, corrugate (corrugated cardboard / fiberboard), and fabrics (including, for example, but not limited to, woven fabric, non-woven fabric, and foil-laminated fabric).

[0157] The inkjet inks may also be printed on non-porous (or non-penetrable substrates), for example, various plastics, glass, metals (e.g., steel, aluminum, etc.), and / or non-penetration papers (e.g., coated papers such as varnish coated papers), including, but not limited to, molded plastic or metal parts as well as flat sheets or rolls of plastic or metallic films. Examples include those substrates containing polyesters such as polyethylene terephthalate (PET), biaxially oriented polystyrene (OPS), polyolefins such as polyethylene (PE), polypropylene (PP), oriented polypropylene (OPP), and biaxially oriented polypropylene (BOPP), polylactic acid (PLA), nylon and oriented nylon, polyvinyl chloride (PVC), cellulose triacetate (TAC), polycarbonate, acrylonitrile butadiene styrene (ABS), polyacetal, polyvinyl alcohol (PVA), coated papers such as varnish coated papers, and metals such as steel and aluminum, and the like.

[0158] Method of Forming a Printed Image

[0159] The method of forming a printed image on a substrate of this invention involves applying the inkjet ink of the present invention onto the substrate with a thermal inkjet printhead and drying the inkjet ink.

[0160] With inkjet printing, a desired printed image is formed when a precise pattern of dots is ejected from a drop-generating device, known as a printhead, onto a print medium. The printhead has an array of precisely formed nozzles located on a nozzle plate and attached to an inkjet printhead substrate. The inkjet printhead substrate incorporates an array of firing chambers that receive inkjet ink through fluid communication with one or more ink reservoirs. Each firing chamber has a resistor element, known as a firing resistor, located opposite the nozzle so that the inkjet ink collects between the firing resistor and the nozzle. Each resistor element is typically a pad of a resistive material and measures, for example, about 35 pm * 35 pm. The printhead is held and protected by an outer packaging referred to as a print cartridge or an inkjet pen. Upon energizing of a particular resistor element, a droplet of inkjet ink is expelled through the nozzle toward the print medium. The firing of ink droplets is typically under the control of a microprocessor, the signals of which are conveyed by electrical traces to the resistor elements, forming alphanumeric and other image patterns on the print medium. Since the nozzles are small, typically 10 pm to 40 pm in diameter, inks that minimize clogging are desired. In particular, since thermal inkjet (TH) printing uses an open atmosphere print head design (the nozzle orifices are open to atmosphere and there is no valve seal at the orifice to allow ink pressurization), TIJ printing has historically suffered from poor performance during intermittent printing, where decap time (print idle time) causes premature drying of ink in and around the nozzles, especially in cold, dry environments.

[0161] The present disclosure provides a method of forming a printed image by applying any of the inkjet inks of the present disclosure, in one or more of its embodiments, onto a surface of a substrate by a thermal inkjet printhead and drying the inkjet ink. Use of the inkjet inks described herein overcomes the problem of short decap time (rate of solvent loss is too fast) commonly associated with thermal inkjet processes, across a range of temperatures and humidities.

[0162] Any drop on demand printhead known to those of ordinary skill in the art of inkjet printing can be used as printing units in the present method, including continuous printheads, thermal printheads, electrostatic printheads, and acoustic printheads, preferably a thermal printhead (having a thermal transducer) is used. Typical parameters, such as, for example, printing resolution, printing speed, printhead pulse warming temperature, driving voltage and pulse length, can be adjusted according to the specifications of the printhead. Printheads which are generally suitable for usage in the methods herein have a droplet size in the range of 2 to 80 pL and a droplet frequency in the range of 10 to 100 kHz, and high quality prints may be obtained for example by setting the driving voltage to 8.0 to 9.5 Volts, the print speed up to 300 feet / minute, the pulse warming temperature to 25 to 45°C, and the pulse length to 0.7-2.5 microseconds, although values above or below these described may also be used and still obtain satisfactory prints. One non-limiting printhead example suitable for use in the disclosed methods is the HP45Si printer cartridge made by Hewlett Packard, or the FUNAI TIJ cartridge made by Funai Co.

[0163] After application, the inkjet ink is dried. In some embodiments, external heat may be applied to dry the applied inkjet inks, for example, using a heater. However, it is preferred that no external heat is applied to facilitate drying or to increase drying speeds. Therefore, in preferred embodiments, drying is achieved by allowing the applied inkjet ink to dry under ambient conditions for 30 seconds or less, preferably 25 seconds or less, more preferably 20 seconds or less, even more preferably 15 seconds or less, yet even more preferably 10 seconds or less, without the use of an external heat source such as a heater. The drying times may be increased or decreased based on ambient temperatures and humidities. Furthermore, the methods of the present disclosure do not require energy curing (e.g., UV or electron beam curing). Once the applied ink is deemed dry, further coatings of inkjet ink may be applied, or any processing steps known to those of ordinary skill in the art may be performed as desired.

[0164] It should also be recognized that substrate surface treatments such as corona treatment, atmospheric plasma treatment, and flame treatment may optionally be employed in the methods herein prior to application of the inkjet inks to improve printed article characteristics, for example ink adhesion. The parameters of such substrate surface treatments may be varied greatly depending on the substrate material to be printed, the specific inkjet ink utilized, the printing method applied, and the desired properties and applications of the printed article.

[0165] The examples below are intended to further illustrate embodiments of the inkjet inks of the present disclosure and are not intended to limit the scope of the claims.

[0166] EXAMPLES

[0167] Materials

[0168] EB Acetate is ethylene glycol monobutyl ether acetate, and PM acetate is propylene glycol methyl ether acetate, each available from Eastman.

[0169] PINECRYSTAL KE-311 is a glycerol ester of hydrogenated rosin, and PINECRYSTAL KE-359 is a pentaerythritol ester of a hydrogenated rosin; each are available from Arakawa Chemical Industries, Ltd.

[0170] PINECLEAR 4306 A and PINEREZ 2308 A are both pentaerythritol esters of stabilized rosin and available from Lawter. FILTREZ 3305 is a maleic modified rosin ester, also available from Lawter.

[0171] DERTOPHENE T 105 is a terpene phenolic resin available from DRT.

[0172] PHENOLITE TD-2090 is a phenolic novolac resin available from DIC Corp.

[0173] JONCRYL 680 is an acrylic resin available from BASF.

[0174] VALIFAST BLACK 3830 is a colorant comprising Solvent Black 27, and is available from Orient Chemical Industries Co., Ltd.

[0175] KF-859 is an amine modified silicone available from Shin-Etsu Chemical Co.

[0176] Inkjet ink examples

[0177] Example inkjet inks are given in Table 1. The amount of each component is expressed in terms of weight percentage based on a total weight (100%) of the inkjet ink.

[0178] * denotes that the example is a comparative example.

[0179] Preparation methods

[0180] The ink was obtained by the following method: The rosin resin, organic solvents, and other ingredients such as amine and surfactant were mixed by a magnetic stir bar until completely dissolved. Dye was added into the mixture and then mixed for 30 min. The print result using these inks are shown in the following table. The inks were then evaluated as described below.

[0181] Inkjet ink evaluation methods

[0182] Printing sample preparation

[0183] The inkjet ink examples were evaluated through a TIJ printer made by HAS using a HP45Si printer cartridge made by Hewlett Packard. The TIJ printer was housed in an EPL- 3H controlled temperature and humidity chamber made by Espec.

[0184] Decap time evaluation

[0185] For evaluating decap times, the printing conditions utilized were as follows:

[0186] - Printing substrate: normal (non-coated) paper

[0187] - Printing resolution: 300 dpi * 300 dpi (vertical *horizontal)

[0188] - Print speed: 7 m / min

[0189] - Pulse width: 1.8 ps

[0190] - Voltage: 8.6 V

[0191] - Pulse warming: OFF

[0192] - Printing image: 100% duty (Monochrome bitmap,) (see e.g., Figs. 1A-1C). The images have a height of 0.5 inches and a length of 2.7 inches.

[0193] - Printing environment: 10 °C (50 °F) at 30% relative humidity or 35 °C (95 °F) at 85% relative humidity.

[0194] An image including a numeric sequence was printed to confirm that there were no missing or unclear lines included in the printed image (signifying plugged or missing nozzles). After confirming, the printhead was left decapped for a specific time (1 min, 3 min, 5, min, 10 min, 15 min, 30 min, 45 min, or 60 min), then the same image was reprinted. The reprinted image (after the specific time lapse) was checked to determine whether loss of lines / loss of line clarity occurred. If no loss of lines / loss of line clarity occurred, then the inkjet inks were given a “Good” decap rating for that time interval. If 1-10 lines were lost, or if clarity was lost at the tested time interval, but not enough to significantly affect the clarity or readability of the image at the tested time interval, then the inkjet ink was given an “Acceptable” decap rating for that time interval. If more than 10 lines were lost, or if clarity and / or readability was significantly lost at the tested time interval, then the inkjet ink was classified as “Not Good” at that time interval. Suitable / desirable inkjet inks are those which achieve an “Acceptable” or “Good” decap classification when decapped (i.e., exposed to air) for each of the tested time intervals and environmental conditions.

[0195] Table 1. Inkjet ink compositions

[0196] SP = Solubility Parameter denotes that the Example is a Comparative Example

[0197] AV = Acid Value, mgKOH / g

[0198] OHV = Hydroxyl Value, mgKOH / g

[0199] Table 1 cont’d.

[0200]

[0201]

[0202] SUBSTITUTE SHEET (RULE 26) Inkjet ink performance

[0203] From Table 2 it can be seen that the combination of rosin resin having an acid value of less than 22 mgKOH / g and a hydroxyl value of 40 mgKOH / g or less, ethanol, and cosolvent having a Hildebrand solubility parameter of less than 11 cal1 / 2cm3 2provided remarkable effects in terms of running stability and decap times at different temperatures and humidities (Examples 1-2 and 10-16). Conversely, inkjet inks formulated with a rosin resin having an acid value of less than 22 mgKOH / g but a hydroxyl value of 43 mg KOH / g, as in Example 5, exhibited poor decap behavior. Inkjet inks formulated with rosin resins having acid values greater than 22 mgKOH / g in Examples 3 and 4 showed acceptable decap performance at 35 °C and 85% humidity, but these inks had poor performance at the cooler and drier conditions of 10 °C and 30% humidity. Inkjet inks formulated with 2-propanol as a cosolvent, which has a Hildebrand solubility parameter of greater than 11 cal1 / 2cm3 2, also exhibited poor decap performance (Example 17).

[0204] In terms of the quantity of rosin resin, loadings in the range of 1 to 5 wt% were found to provide excellent decap behavior, along with cosolvent concentrations in a range of 2.5 to

[0205] 10 wt% (Examples 1-2 and 10-16).

Claims

CLAIMS1. An inkjet ink, comprising:(A) a rosin resin having an acid value of less than 22 mgKOH / g and a hydroxyl value of 40 mg KOH / g or less;(Bl) an alcohol; and(B2) a cosolvent having a Hildebrand solubility parameter of less than 11 cal1 / 2cm3 2, wherein a weight ratio of the cosolvent (B2) to the rosin resin (A) ((B2):(A)) is 1 : 1 to 10: 1.

2. The inkjet ink of claim 1, wherein the rosin resin (A) is present in an amount of 0.1 to 10 wt%, based on a total weight of the inkjet ink.

3. The inkjet ink of claim 1, wherein the rosin resin (A) comprises a modified rosin resin (Al).

4. The inkjet ink of claim 3, wherein the modified rosin resin (Al) comprises a rosin ester.

5. The inkjet ink of claim 4, wherein the rosin ester comprises at least one selected from the group consisting of a glycerol ester of a hydrogenated rosin, a glycerol esterified rosin, a pentaerythritol ester of a hydrogenated rosin, a pentaerythritol esterified rosin, a triethylene glycol esterified rosin, a maleic modified rosin ester, and a methyl esterified rosin.

6. The inkjet ink of claim 1, wherein the alcohol (Bl) is present in an amount of 75 to90 wt%, based on a total weight of the inkjet ink.

7. The inkjet ink of claim 1, wherein the alcohol (Bl) comprises at least one selected from the group consisting of methanol, ethanol, 1 -propanol, 2-propanol, 1 -butanol, 2-butanol, 2-pentanol, 3-pentanol, and t-amyl alcohol.

8. The inkjet ink of claim 1, wherein the alcohol (Bl) comprises ethanol.

9. The inkjet ink of claim 1, wherein the cosolvent (B2) is present in an amount of 1 to 20 wt%, based on a total weight of the inkjet ink.

10. The inkjet ink of claim 1, wherein the cosolvent (B2) is at least one selected from the group consisting of ethylene glycol monobutyl ether acetate, propylene glycol methyl ether acetate, acetone, and cyclohexanone.

11. The inkjet ink of claim 1, further comprising (C) a colorant.

12. The inkjet ink of claim 11, wherein the colorant (C) is present in an amount of 0.1 to 15 wt%, based on a total weight of the inkjet ink.

13. The inkjet ink of claim 1, further comprising (D) a silicone.

14. The inkjet ink of claim 13, wherein the silicone (D) is present in an amount of 0.001 to 4 wt%, based on a total weight of the inkjet ink.

15. The inkjet ink of claim 1, further comprising (E) a pH adjuster in an amount of 0.1 to 5 wt%, based on a total weight of the inkjet ink.

16. The inkjet ink of claim 15, wherein the pH adjuster (E) comprises an amine.

17. The inkjet ink of claim 16, wherein the amine comprises an alkanolamine.

18. A printed article, comprising: a substrate and a dried form of the inkjet ink of claim 1 disposed on the substrate.

19. A method of forming a printed image on a substrate, comprising: applying the inkjet ink of claim 1 onto the substrate with a thermal inkjet printhead; and drying the inkjet ink.

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