Solvent-based inkjet inks

Abstract

An inkjet ink includes: a rosin resin having 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 HildBland solubility parameter of less than 11 cal1 / 2 cm <-3 > / 2. The inkjet inks are characterized by an extended unsealing time under a range of environmental conditions, and additionally have good operational stability and drying time. A printed article including the inkjet ink in dry form and a method of forming a printed image with a thermal inkjet printhead are also provided.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application is based upon and claims the benefit of priority from International Patent Application No. PCT / US2023 / 014036, filed on February 28, 2023. The entire contents of that application are incorporated herein by reference. Technical Field

[0003] The present invention relates to solvent-based inkjet inks, methods of making such inkjet inks, and methods of forming images using such inkjet inks. Background Art

[0004] The "background" description provided herein is intended to generally present the context of the present disclosure. To the extent described in this background section, the work of the inventors, as well as aspects of the description that may not be considered prior art at the time of filing, are not explicitly or implicitly admitted to be prior art against the present invention.

[0005] Thermal inkjet (TIJ) printing is an ideal printing, coding, and marking technology because it offers high print resolution at a lower cost than competing technologies in this field, such as continuous inkjet (CIJ) methods. In the thermal inkjet printing process, the print cartridge contains an array of tiny chambers, each containing a heater, which produces ink droplets through the thermal evaporation of the ink solvent. In the jetting process, a resistor is rapidly heated to create a vapor bubble (hence the term "bubble jet"), which then ejects a droplet from a nozzle orifice. The process is very efficient and repeatable, and modern TIJ printheads used for industrial graphics applications can produce uniform droplets with a volume of less than 4 pL at frequencies exceeding 36 kHz.

[0006] However, industrial marking and coding often requires printing essential information onto substrates, such as personal information, labels, codes, dates (e.g., expiration dates), and traceability information (e.g., production batches). Furthermore, this printing occurs under a variety of environmental conditions, such as printing in a cold room to label refrigerated foods or printing in warm outdoor environments to label wood products. Thermal inkjet printing can suffer from poor reliability after periods of inactivity. For example, some inkjet inks have a short decap time, during which solvent loss occurs due to prolonged exposure to air within the uncapped printhead. This can lead to clogging / clogging of the printhead nozzles, resulting in unreliable inkjet printing and image quality degradation over time. This degradation is often more severe in low-temperature / low-humidity and high-temperature / high-humidity environments. Poor image quality is unacceptable for many applications, especially those involving the marking and encoding of critical information. For this reason, despite its other advantages, TIJ technology has only modest acceptance in marking / coding applications and is limited by environmental conditions.

[0007] It has been reported that solvent-based inkjet inks made using a specific combination of phenolic resin, rosin resin ester, and organic solvent have acceptable open time, see US20180072902A1 - incorporated herein by reference in its entirety. However, this ink system was not compared in cold and dry and warm and humid environments. SUMMARY

[0008] In view of the above, there is a need for inkjet inks having extended open time under a range of temperature and humidity conditions.

[0009] It is therefore an object of the present invention to provide novel inkjet inks that meet these criteria.

[0010] It is a further object of the present disclosure to provide novel printed articles comprising the inkjet inks in dried form.

[0011] It is a further object of the present disclosure to provide novel methods of forming printed images on a substrate by jetting an inkjet ink onto the substrate and drying.

[0012] These and other objects will become apparent from the following detailed description, which has been arrived at by the present inventor through the following discovery: the combination of a rosin resin having an acid value of less than 22 mgKOH / g and a hydroxyl value of 40 mgKOH / g or less, an alcohol, and a co-solvent having a Hildebrand solubility parameter of less than 11 cal 1 / 2 cm -3 / 2 provides an inkjet ink characterized by extended open time under a range of environmental conditions, as well as good run stability.

[0013] Accordingly, the present invention provides:

[0014] (1) An inkjet ink comprising:

[0015] (A) a rosin resin having an acid value of less than 22 mgKOH / g and a hydroxyl value of 40 mgKOH / g or less;

[0016] (B1) an alcohol; and

[0017] (B2) a co-solvent having a Hildebrand solubility parameter of less than 11 cal 1 / 2 cm -3 / 2 ,

[0018] wherein the weight ratio of co-solvent (B2) to rosin resin (A) ((B2):(A)) is from 1:1 to 10:1.

[0019] (2) 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 mgKOH / g or less; and

[0021] (B) a solvent system comprising:

[0022] (B1) an alcohol, and

[0023] (B2) a co-solvent having a Hildebrand solubility parameter of less than 11 cal 1 / 2 cm -3 / 2 ,

[0024] wherein the weight ratio of the co-solvent (B2) to the rosin resin (A) ((B2):(A)) is from 1:1 to 10:1.

[0025] (3) The inkjet ink according to (1) or (2), wherein the rosin resin (A) is present in an amount of 0.1 to 10 wt% based on the total weight of the inkjet ink.

[0026] (4) The inkjet ink according to any one of (1) to (3), wherein the rosin resin (A) comprises a modified rosin resin (A1).

[0027] (5) The inkjet ink according to any one of (1) to (4), wherein the modified rosin resin (A1) comprises a rosin ester.

[0028] (6) The inkjet ink according to (5), wherein the rosin ester comprises at least one selected from the group consisting of hydrogenated rosin glycerol ester, glycerol esterified rosin, hydrogenated rosin pentaerythritol ester, pentaerythritol esterified rosin, triethylene glycol esterified rosin, maleic acid modified rosin ester, and methyl esterified rosin.

[0029] (7) The inkjet ink according to any one of (1) to (6), wherein the alcohol (B1) is present in an amount of 75 to 90 wt% based on the total weight of the inkjet ink.

[0030] (8) The inkjet ink according to any one of (1) to (7), wherein the alcohol (B1) 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.

[0031] (9) The inkjet ink according to any one of (1) to (8), wherein the alcohol (B1) comprises ethanol.

[0032] (10) The inkjet ink according to any one of (1) to (9), wherein the co-solvent (B2) is present in an amount of 1 to 20 wt% based on the total weight of the inkjet ink.

[0033] (11) The inkjet ink according to any one of (1) to (10), wherein the co-solvent (B2) is at least one selected from the group consisting of ethylene glycol monobutyl ether acetate, propylene glycol methyl ether acetate, acetone, and cyclohexanone.

[0034] (12) The inkjet ink according to any one of (1) to (11), further comprising (C) a colorant.

[0035] (13) The inkjet ink according to (12), wherein the colorant (C) is present in an amount of 0.1 to 15 wt% based on the total weight of the inkjet ink.

[0036] (14) The inkjet ink according to any one of (1) to (13), further comprising (D) a silicone.

[0037] (15) The inkjet ink according to (14), wherein the silicone (D) is present in an amount of 0.001 to 4 wt% based on the total weight of the inkjet ink.

[0038] (16) The inkjet ink according to any one of (1) to (15), further comprising (E) a pH adjuster in an amount of 0.1 to 5 wt% based on the total weight of the inkjet ink.

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

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

[0041] (19) A printed article comprising:

[0042] a substrate and a dried form of the inkjet ink according to any one of (1) to (18) disposed on the substrate.

[0043] (20) A method of forming a printed image on a substrate, comprising:

[0044] applying the inkjet ink according to any one of (1) to (18) to the substrate with a thermal inkjet printhead; and

[0045] drying the inkjet ink. BRIEF DESCRIPTION OF DRAWINGS

[0046] The above paragraph is provided by way of general introduction, and is not intended to limit the scope of the following claims. The described implementations, together with further advantages, will be best understood from the following detailed description taken in connection with the accompanying drawings, in which:

[0047] FIG. 1A Opening time evaluation showing a "good" rating, with an image size of 2.7 inches x 0.5 inches (6.9 cm x 1.8 cm).

[0048] FIG. 1B Unpacking time assessment showing a "Acceptable" rating with an image size of 2.7 inches x 0.5 inches (6.9 cm x 1.8 cm).

[0049] FIG. 1C Unpacking time assessment showing a "Poor" rating with an image size of 2.7 inches x 0.5 inches (6.9 cm x 1.8 cm). DETAILED DESCRIPTION

[0050] In the following description, it is to be understood that other embodiments can be used and structural and operational changes can be made without departing from the scope of the embodiments disclosed herein.

[0051] The present disclosure will be better understood with reference to the following definitions. As used herein, the terms "a" and "an" shall mean "one or more" and "at least one," respectively. In the description of the disclosure, if a limit or range is specified, unless otherwise specified, the endpoints are included. It will be further understood that the use of the terms "include," "includes," and / or "comprise," or "comprises," as used herein, specifies the presence of stated features, integers, steps, operations, elements, and / or components but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0052] Regardless of any particular expressed herein, the present disclosure also contemplates other embodiments "comprising," "consisting of," and "consisting essentially of," the embodiments or elements presented herein. Obviously, many modifications and variations of the present application are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims, the application can be practiced otherwise than as specifically described. All patents and other references mentioned herein are incorporated in their entirety by reference as if fully set forth.

[0053] The words "about," "approximately," or "substantially" as used herein, can be used to describe quantitatively approximating or estimating some quantity or value as being close to a reference quantity or value. For example, a numerical value can be + / - 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). In the description of the disclosure, if a numerical limit or range is stated, the endpoints are included unless otherwise specified. Further, all values and subranges within a numerical limit or range are expressly included, as if expressly written out.

[0054] Unless otherwise indicated, the phrase "substantially free of" describes an amount of a particular component in an inkjet ink that is 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%, still even more preferably 0 wt%, based on the total weight of the inkjet ink.

[0055] The term "optional" or "optionally" as used herein means that the subsequently described event or element can or can not occur, or that the subsequently described component can or can not be present (e.g., 0 wt%).

[0056] "Compound" as used herein means a chemical entity, whether solid, liquid, or gas, and whether a crude mixture or isolated and purified.

[0057] Unless otherwise indicated, the term "alkyl" as used herein means a straight chain, branched, or cyclic aliphatic moiety 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-propylheptyl, 2-butyloctyl, 2-pentylnonyl, 2-hexyldecyl, 2-heptylundecyl, 2-octyldodecyl, 2-nonyltridecyl, 2-decatetradecyl, and 2-undecapentadecyl). Cyclic alkyl is a type of cyclic alkyl group. Exemplary cyclic alkyl groups include, but are not limited to, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, norbornyl, and adamantyl.

[0058] The term "fatty" as used herein describes a compound having a long chain (straight chain) hydrophobic portion consisting of hydrogen and 8 to 22 carbon atoms, which can be fully saturated or partially unsaturated.

[0059] The term "aryl" as used herein means an aryl group containing only carbon in the aromatic ring, such as phenyl, biphenyl, naphthyl, anthryl, and the like.

[0060] As used herein, the term "aralkyl" refers to a linear, branched, or cyclic alkyl group (as defined above) substituted by an aryl group (as defined above), which itself may 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.

[0061] The term "(meth)acrylate" is used herein to refer to both acrylate and methacrylate groups. In other words, this term should be understood as meaning that the "meth" is optional. Furthermore, the term "(meth)acrylate" is generally used to refer to both acrylic and acrylate compounds.

[0062] Throughout this specification, unless otherwise indicated, the term "boiling point" (bp) refers to the boiling point of a liquid measured at atmospheric pressure at sea level (ie, 760 mmHg or 1 atmosphere), also known as the normal boiling point.

[0063] As used herein, the term "decapping behavior" refers to the ability of an inkjet ink to readily eject from a printhead when exposed to air for extended periods. The "decapping time" of an inkjet ink is measured as the time an inkjet printhead can remain uncapped before the printer, potentially causing the nozzles to no longer eject properly due to a blockage or clogging when resuming printing. Typically, nozzles can become blocked (i.e., hindered, slowed) or clogged (i.e., hindered, substantially or completely closed) by a viscous plug that forms in the nozzles due to solvent loss, ink skinning, and / or scaling of various ink components in and / or around any nozzle. If a nozzle becomes clogged, ink droplets ejected through the nozzle orifice may be misdirected, which can adversely affect print quality. When a nozzle orifice becomes clogged, it becomes substantially or completely blocked. Due to the clogged nozzle, ink droplets may be unable to pass through the affected nozzle. Therefore, the criterion for measuring nozzle non-jetting is the misdirection of ink through the nozzle orifice to a minor or major degree, or complete blockage, which can be measured by visual inspection of the printed image.

[0064] Inkjet ink

[0065] The present disclosure relates to inkjet inks that have suitable physical and chemical stability at both ambient temperature and printhead operating temperature, are reliably jetted, have extended open times over a wide range of environmental conditions, while still drying quickly after application to a substrate and having good operational stability.

[0066] The inkjet ink of the present disclosure generally includes the following components: (A) a rosin resin having an acid value of less than 22 mgKOH / g and a hydroxyl value of 40 mgKOH / g or less; (B1) an alcohol; and (B2) a co-solvent having a Hildebrand solubility parameter of less than 11 cal 1 / 2 cm -3 / 2 .

[0067] The inkjet ink of the present disclosure can also optionally include one or more of the following: (A1) a modified rosin resin; (C) a colorant; (D) a silicone; (E) a pH adjuster; and (F) an additive.

[0068] (A) rosin resin

[0069] The inkjet ink of the present disclosure is formulated from a rosin resin (A). Generally, the amount of rosin resin (A) is preferably 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 the total weight of the inkjet ink. In one embodiment, the rosin resin (A) is preferably present in an amount of 0.1 to 10 wt%, more preferably 0.5 to 8 wt%, even more preferably 1.0 to 7 wt%, even more preferably 1.5 to 6 wt%, or even more preferably 2.5 to 5 wt%, based on the total weight of the inkjet ink.

[0070] Rosin (A) can be derived from gum rosin; B, C, D, E, F, FF, G, H, I, J, K, L, M, N, W-G, W-W grades of wood rosin (as defined by ASTM 0509 standard); virgin rosin; hard rosin; yellow dip rosin; NF wood rosin; tall oil rosin; or colophony or colophonium and any single component of natural rosin nature, such as abietic acid, abietinic acid, sylvic acid, dihydroabietic acid, tetrahydroabietic acid, dehydroabietic acid, neoabietic acid, isocupressic acid, levopimaric acid, isohop- ponic acid, sandaracopimaric acid, longifolene acid, dextro pimaric acid, isodextropimaric acid, dextropimarinal, isodextropimarinal, xanthoperol, tatarol, podocarpic acid, phyllocladen, sugiol, himokiol, manool, manoyloxide, ketomanoyloxide, cativinic acid, eperuanic acid and all other rosin components based on the diterpene skeleton of abietic acid; and any mixture thereof having at least one carboxylic, sulfonic or phosphoric acid for silylation, if necessary, by oxidation. The term "rosin" can indicate any mixture of the above chemicals, as well as any one of the chemicals themselves.

[0071] Rosin (A) preferably includes modified rosin (A1). Such modified rosin can be formed by modifying rosin through esterification, hydrogenation (including partial hydrogenation), dimerization and / or other modifications / functionalization (e.g., by Diels-Alder reaction with an unsaturated diacid such as maleic acid or fumaric acid / anhydride, reduction of carboxylic acid to the corresponding aldehyde / alcohol, double bond isomerization, dehydrogenation, oxidation, disproportionation, etc.).

[0072] In a preferred embodiment, modified rosin (A1) includes rosin esters.

[0073] In one embodiment, rosin esters include rosin, hydrogenated rosin, some other modified rosin esterified with glycerol, pentaerythritol, triethylene glycol, ethylene glycol, diethylene glycol, methanol and / or maleic acid.

[0074] Exemplary rosin esters include, but are not limited to, HARIESTER products available from Harima Chemicals, Inc.; hydrogenated rosin glycerol esters such as STAYBELITE ESTER 10-E, and pentaerythritol esters of gum rosin such as PERMALYN 6110, all of which are available from Eastman; highly stabilized rosin esters such as SUPER ESTER A-125, SUPER ESTER A-75, polymeric rosin esters such as PENSEL D-125, hydrogenated rosin esters such as PINECRYSTAL KE-100, hydrogenated rosin glycerol esters such as PINECRYSTAL KE-311, and hydrogenated rosin pentaerythritol esters such as PINECRYSTAL KE-359, all of which are available from Arakawa Chemical Industries, Ltd.; stabilized rosin pentaerythritol esters such as PINEREZ 2308A and PINECLEAR 4306A, maleic acid-modified rosin esters such as FILTREZ 3305, all of which are available from Lawter; hydrogenated wood rosin glycerol esters such as FORAL 85, hydrogenated rosin pentaerythritol esters such as FORAL 105, hydrogenated rosin methyl esters such as HERCOLYN D, all of which are available from DRT; partially dimerized rosin glycerol esters such as PEXALYN ESTER 10, rosin glycerol esters such as PEXALYN 9085, stabilized rosin pentaerythritol esters such as PEXALYN 9100, and pentaerythritol esters of wood rosin stabilized by hydrogenation such as PENTALYN H, all of which are available from Pinova, Inc.; and functionalized rosin resins such as esters (e.g., glycerol esters) of rosin modified with maleic anhydride or rosin subjected to carboxylic acid reduction conditions, particularly LEWISOL 28-M available from Synthomer.

[0075] In addition to rosin esters, other exemplary modified rosin resins (A1) include, but are not limited to: hydrogenated acid rosin such as FORAL AX and FORAL DX, both of which are available from Pinova; partially hydrogenated acid rosin such as STAYBELITE RESIN-E available from Synthomer; STAYBELITE and STAYBELITE A, both of which are available from Pinova; dimerized rosin such as POLY-PALE available from Synthomer; and ABITOL E hydrogenated rosin alcohol available from Synthomer.

[0076] In one embodiment, the modified rosin resin (A1) preferably comprises at least one selected from the group consisting of hydrogenated rosin glycerin ester, glycerin esterified rosin, hydrogenated rosin pentaerythritol ester, pentaerythritol esterified rosin, triethylene glycol esterified rosin, maleic acid-modified rosin ester, and methyl esterified rosin. In a preferred embodiment, the modified rosin resin (A1) comprises hydrogenated rosin glycerin ester.

[0077] In one embodiment, the rosin resin (A) comprises both the modified rosin resin (A1) and the unmodified rosin resin. For example, the rosin resin (A) can comprise, based on the total weight of the modified rosin resin (A1) and the unmodified rosin resin, 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 99 wt% of the modified rosin resin (A1).

[0078] In one embodiment, the rosin resin (A) has a 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 25 mg 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 more than 1 mg KOH / g, more preferably more than 5 mg KOH / g, even more preferably more than 8 mg KOH / g. The hydroxyl value (OHV) is defined as the milligrams of potassium hydroxide required to neutralize the acetylation of one gram of a chemical substance containing free hydroxyl groups to produce acetic acid. The hydroxyl value can be determined according to Japanese Industrial Standard JIS K 0070: 1992 “Test methods of acid value, saponification value, ester value, iodine value, hydroxyl value and unsaponifiable matter of chemical products”.

[0079] 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 the 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. Acid value indicates the amount of potassium hydroxide (mg) required to completely neutralize 1 g of resin. Acid value can also be determined according to the above-mentioned Japanese Industrial Standard JIS K 0070: 1992. Exemplary embodiments of rosin resins (A) having an acid value of less than 22 mgKOH / g include, but are not limited to, PINECRYSTAL KE-311 (AV = 6 mgKOH / g, OHV = 9 mgKOH / g) (hydrogenated rosin glyceride from Arakawa Chemical Industries, Ltd.) and PINECLEAR 4306A (AV = 18 mgKOH / g, OHV = 25 mgKOH / g) (rosin ester from Lawter).

[0080] Modified rosin resins (A1) having an acid value of less than 22 mgKOH / g and a hydroxyl value of 40 mgKOH / g or less are used in combination with a co-solvent (B2) having a Hildebrand solubility parameter of less than 11 cal 1 / 2 cm -3 / 2 and an alcohol (B1) are found to provide excellent unseal time while maintaining good dry time. Without being bound by theory, it is believed that the modified rosin resin (A1) improves the unseal behavior of the inkjet ink by forming a thin "skin" or film covering within the print head nozzle, creating a temporary seal that prevents or reduces solvent loss during periods of inactivity, but this "skin" can be easily broken once printing operations are resumed.

[0081] (B) Solvent system

[0082] In many printing processes utilizing solvent-based inks, particularly thermal inkjet printing, the selection of a suitable solvent system can impact the reliability of the printing process, the performance / appearance of the printed ink product, and the overall printing process efficiency. For example, in thermal inkjet printing, the selection of a solvent system can: 1) contribute to the formation of bubbles in the jetting process, leading to reliable ink ejection; 2) affect the stability / volatility of the inkjet ink, and thus the unsealing behavior, galling, and / or drop trajectory, by changing the interaction kinetics between the solvent and various inkjet ink components; 3) affect the adhesion, rub and scratch resistance, and optical density performance of the printed image, through the interaction forces between the solvent system and other inkjet ink components, even though the solvent can no longer be present or can be present at a reduced level after drying; 4) affect the drying time after jetting or the equipment required to dry the jetted ink; and / or 5) affect the droplet dynamics.

[0083] In view of the above, it is particularly preferred to have an inkjet ink with a solvent system (B) comprising an alcohol (B1) and a co-solvent (B2) having a Hildebrand solubility parameter of less than 11 cal 1 / 2 cm -3 / 2 .

[0084] The alcohol (B1) of the present disclosure refers to a compound in which one hydrogen atom of an alkyl group is replaced by a hydroxyl group, i.e. a compound having an alkyl group and a hydroxyl group.

[0085] The alcohol (B1) can be present in the inkjet ink in an amount of 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 the total weight of the inkjet ink. In one embodiment, the alcohol (B1) is preferably present in an amount of 75 to 92 wt%, more preferably 76 to 88 wt%, or even more preferably 76 to 80 wt%, based on the total weight of the inkjet ink.

[0086] In one embodiment, the alcohol (B1) can contain at least 1 carbon atom, preferably at least 2 carbon atoms, and at most 8 carbon atoms, preferably at most 6 carbon atoms, more preferably at most 5 carbon atoms, more preferably at most 4 carbon atoms, more preferably at most 3 carbon atoms. Preferred alcohols (B1) are those having 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.

[0087] In one embodiment, the alcohol (B1) 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 (B1) comprises at least one selected from the group consisting of methanol, ethanol, 1-propanol, and 2-propanol. In a preferred embodiment, the alcohol (B1) comprises ethanol.

[0088] The inclusion of a co-solvent (B2) can aid in the solvation of the inkjet ink components, provide polarity compatibility with the rosin resin (A) to achieve the desired unsealing behavior, and provide an acceptable volatility to the inkjet ink for the purpose of drying time. The co-solvent (B2) can be present in the inkjet ink in a preferred amount of 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 the total weight of the inkjet ink. In one embodiment, the co-solvent (B2) is preferably present in an amount of 1 to 20 wt%, more preferably 2 to 15 wt%, even more preferably 2.5 to 10 wt%, based on the total weight of the inkjet ink.

[0089] The Hildebrand solubility parameter of the co-solvent (B2) is less than 11 cal 1 / 2 cm -3 / 2 , preferably less than 10.5 cal 1 / 2 cm -3 / 2 , and / or preferably greater than 7.5 cal 1 / 2 cm -3 / 2 , more preferably greater than 8 cal 1 / 2 cm -3 / 2 , even more preferably greater than 8.5 cal 1 / 2 cm -3 / 2 . In one embodiment, the Hildebrand solubility parameter of the co-solvent (B2) is preferably in the range of 7.5 to 11 cal 1 / 2 cm -3 / 2 , more preferably 8 to 10.5 cal 1 / 2 cm -3 / 2 , or even more preferably 8.5 to 10.5 cal 1 / 2 cm -3 / 2 .

[0090] The Hildebrand solubility parameter (δ) is a value listed for many different polymers and solvents that can be used to estimate miscibility. In the present application, the Hildebrand solubility parameter (δ) is expressed in cal 1 / 2 cm -3 / 2calculated by the following equation

[0091] ,

[0092] where ΔΗ υ is the enthalpy of vaporization of the target solvent, R is the gas constant, T is the temperature, V m is the molar volume of the target solvent. Solvents with Hildebrand solubility parameters δ less than 11 cal 1 / 2 cm -3 / 2 at room temperature include, but are not limited to, ethylene glycol monobutyl ether acetate (δ = 8.90 cal 1 / 2 cm -3 / 2 ), propylene glycol methyl ether acetate (8.90 cal 1 / 2 cm -3 / 2 ), acetone (9.77 cal 1 / 2 cm -3 / 2 ), cyclohexanone (10.40 cal 1 / 2 cm -3 / 2 ), n-pentane (7.0 cal 1 / 2 cm -3 / 2 ), n-hexane (7.24 cal 1 / 2 cm -3 / 2 ), diethyl ether (7.62 cal 1 / 2 cm -3 / 2 ), ethyl acetate (9.1 cal 1 / 2 cm -3 / 2 ), chloroform (9.21 cal 1 / 2 cm -3 / 2 ), dichloromethane (9.93 cal 1 / 2 cm -3 / 2 ), methyl ethyl ketone (9.0 cal 1 / 2 cm -3 / 2 ), and 1,3-dioxolane (8.6 cal 1 / 2 cm -3 / 2 ).

[0093] In one embodiment, the co-solvent (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 co-solvent (B2) comprises ethylene glycol monobutyl ether acetate.

[0094] In one embodiment, the weight ratio of co-solvent (B2) to 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.

[0095] In some embodiments, the inkjet ink preferably is 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.

[0096] In some embodiments, the inkjet ink of the present disclosure preferably is substantially free of water, meaning that no water is added to the inkjet ink other than an incidental amount of moisture that can come from ambient conditions. For example, the inkjet ink can include less than 1 wt%, less than 0.5 wt%, less than 0.1 wt%, less than 0.05 wt%, less than 0.01 wt% of water, or can include 0 wt% of water, based on the total weight of the inkjet ink.

[0097] (C) colorant

[0098] The inkjet ink of the present disclosure preferably includes a colorant (C) to provide a color ink that can be used for various printing purposes, and the inkjet ink is not limited to any particular color. Such a colorant (C) is also capable of improving lightfastness, weather resistance, etc. of a printed image in addition to providing color to the inkjet ink. Any colorant (C) can be used in the inkjet ink to provide a desired color, including dyes, pigments, and mixtures thereof, etc., provided that the colorant (C) can be dissolved or dispersed within the inkjet ink. Suitable colors include, for example, cyan, magenta, yellow, and black (“CMYK”), white, orange, green, light cyan, light magenta, violet, etc., including both spot colors and process colors. The inkjet ink can be formulated with various dyes, with metal complex dyes being particularly preferred.

[0099] In one embodiment, the metal complex dye used as the colorant (C) is further a metal complex azo dye, which is a compound formed from a metal center and a ligand that includes an azo functional group (also referred to as a diazenyl functional group). Typically, the ligand that includes the azo functional group is a molecule that can itself be considered an azo dye.

[0100] The ligand comprising the azo functional group coordinates to a metal center, which is typically a transition metal, a main group metal, or a metalloid, but not an alkali metal or an alkaline earth metal. Examples of suitable metals that can 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 can occur through any suitable functional group present on the ligand.

[0101] 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 can be positively charged, negatively charged, or uncharged. In embodiments where the metal complex is positively charged, the metal complex azo dye can further comprise any suitable anion for charge balance. Examples of such suitable anions include, but are not limited to, carboxylate, halide, sulfate, phosphate, hydrogen phosphate, dihydrogen phosphate, nitrate, and mixtures thereof. In embodiments where the metal complex is negatively charged, the metal complex azo dye can 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.

[0102] 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.

[0103] Among them, more suitable examples include onium salts of solvent black 27, solvent black 29, solvent yellow 79, basic red 1, and acid yellow 23. Commercial products of solvent black 27 include VALIFAST Black 3820, VALIFAST Black 3830, and VALIFAST Black 3840; commercial products of solvent black 29 include VALIFAST Black 3808 and VALIFAST Black 3870. Commercial products of onium salts 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 which are available from Orient Chemical Industry Co., Ltd.). Among them, solvent black 27 is more preferred.

[0104] In some embodiments, the inkjet ink comprises a colorant (C) in an amount of preferably 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 up to 10 wt %. In one embodiment, the colorant (C) is preferably present 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 the total weight of the inkjet ink.

[0105] (D) Silicone

[0106] In some embodiments, the inkjet ink preferably further comprises silicone (D). Silicone (D) controls ink wettability, contributing to improved image quality. Silicone (D) can act as a surfactant, providing numerous benefits, including anti-blocking, ink receptivity, leveling, anti-cratering, enhanced surface slip, and / or substrate wetting, without sacrificing the inkjet ink's decapping properties.

[0107] As silicone (D), amine-modified silicone, polyether-modified silicone, carboxyl-modified silicone, alkyl-modified silicone, and aralkyl-modified silicone are preferred from the viewpoint of improving wettability, and amine-modified silicone is preferred from the viewpoint of improving substrate adhesion.

[0108] In one embodiment, the silicone (D) is an amine-modified silicone. The amine-modified silicone can be a block copolymer having a pendent graft structure comprising or consisting of: (i) a silicone backbone (main chain); and (ii) one or more organic amine side chains attached to the silicone backbone; and optionally (iii) one or more fatty alkyl side chains attached to the silicone backbone. Thus, a material meets the definition of "amine-modified silicone" so long as at least one organic amine side chain is attached to the silicone backbone, regardless of whether other types of side chains (e.g., fatty alkyl side chains) are also attached to the silicone backbone. Preferably, there are no other side chains in the amine-modified silicone other than the organic amine side chains and the optional fatty alkyl side chains.

[0109] A "side chain" as referred to herein is not an extension of the silicone backbone (as is the case in linear block copolymers, e.g., A-B-A structures), but rather is attached to the silicone backbone (main chain) as a pendent graft, thereby forming a branching point on the silicone backbone, the side chain extending from the silicone backbone via a covalent bond. Preferred organic amine-modified silicones are those that are non-hydrolysable, i.e., in which the side chain is attached to the silicone backbone via a Si-C bond.

[0110] < (i) silicone backbone>

[0111] The silicone backbone can be based on any organosilicon polymer or oligomer (polyorganosiloxane) having a linear or branched structure of variable molecular weight, which can be formed from the polymerization and / or polycondensation of appropriately functionalized silanes, and which has a polysiloxane backbone structure (silicon atoms linked together via oxygen atoms,— Si— O— Si—), in which alkyl, aryl, and / or aralkyl groups are directly bonded to the (tetravalent) silicon atoms. For example, the polyorganosiloxane backbone can be a linear structure, including but not limited to a polydimethylsiloxane (dimethylsiloxane) backbone (in which 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, specifically mentioning polydimethylsiloxyethyl dimethylsiloxane.

[0112] < (ii) organic amine side chain>

[0113] The amine-modified silicone contains at least one organic amine side chain, which is based on an organic amine or amine-containing polymer, such as a polyaziridine, e.g., a side chain formed from the ring-opening polymerization of one or more alkylene imines, with ethylene imine (aziridine) and propylene imine being most preferred, including copolymers thereof, such as block copolymers. Preferably, the organic amine side chain is an alkyl amine, aryl amine, aralkyl amine, aliphatic amine, or polyaziridine extending from the silicone backbone.

[0114] The organic amine side chains can include primary amines, secondary amines, tertiary amines, or combinations thereof. Such amines can be present in any suitable amount, for example, from 1 to 1,000. In some embodiments, preferred organic amine side chains are selected from monoamines including primary amines and diamines including primary and secondary amines. Such monoamines can be alkyl amines, aryl amines, aralkyl amines, or aliphatic amines. Such diamines can be alkyl amines, aryl amines, aralkyl amines, or aliphatic amines.

[0115] < (iii) aliphatic alkyl side chains

[0116] The amine-modified silicone can also optionally be modified with one or more aliphatic alkyl side chains, for example, aliphatic alkyl side chains containing at least 8 carbon atoms, preferably at least 10 carbon atoms, more preferably at least 12 carbon atoms, and at most 22 carbon atoms, preferably at most 20 carbon atoms, more preferably at most 18 carbon atoms, even more preferably at most 16 carbon atoms, still more preferably at most 14 carbon atoms. Exemplary aliphatic alkyl side chain groups include, but are not limited to, capryl, nonyl, decyl, undecyl, lauryl, tridecyl, myristyl, pentadecyl, cetyl, oleyl, heptadecyl, stearyl, oleyl, eicosyl, and behenyl, with particular mention of lauryl, myristyl, cetyl, and stearyl, preferably lauryl.

[0117] < (iv) polyether side chains

[0118] The amine-modified silicone can also optionally be modified with one or more polyether side chains. The polyether side chains can be based on polyalkylene glycol oligomers or polymers, for example, polyether side chains formed from ring-opening polymerization of one or more alkylene oxides, most preferably ethylene oxide (EO), propylene oxide (PO), and / or butylene oxide (BO), including copolymers thereof, such as block copolymers. Preferably, the polyether side chains are polyethylene glycol or polyethylene glycol-polypropylene glycol copolymers extending from the silicone backbone, more preferably the polyether side chains are polyethylene glycol side chains formed from ethylene oxide (EO) only.

[0119] Polyether side chains of various lengths can generally be used, typically, the number of alkylene oxide units per side chain is at least 2, preferably at least 3, more preferably at least 4, even more preferably at least 5, still even more preferably at least 6, and at most 50, preferably at most 40, preferably at most 30, preferably at most 20, preferably at most 15, more preferably at most 12, even more preferably at most 10, still more preferably at most 9, particularly preferably from 3 to 10 moles, preferably from 4 to 9 moles of ethylene oxide (EO) units per side chain.

[0120] Furthermore, any polyether side chains present can be uncapped (where the polyether side chain opposite the silicone backbone terminates in -H, forming a terminal hydroxyl functional group), or can be capped with an alkyl group having 1, 2, 3, or 4 carbon atoms (forming a terminal alkyl ether group), with particular mention of methyl, ethyl, propyl, and butyl.

[0121] In some embodiments, the amine-modified silicone is a block copolymer having a pendent graft structure, for example represented by formula (I-A).

[0122]

[0123] wherein:

[0124] 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 at most 500, preferably at most 400, preferably at most 300, more preferably at most 200, even more preferably at most 100, yet even more preferably at most 50;

[0125] p represents the number of constituent units containing an organic amine 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 at most 100, preferably at most 80, preferably at most 60, more preferably at most 40, even more preferably at most 20, yet even more preferably at most 10; and

[0126] A is an amine-containing group (organic amine) as described above.

[0127] In some embodiments, preferred amine-modified silicones are block copolymers having a pendent graft structure, having a diamine structure including primary and secondary amines, for example represented by formula (I-B).

[0128]

[0129] Preferred amine-modified silicones having the above structure are KF-859, KF-393, KF-860, KF-880, KF-8004, KF-8002, KF-8005, KF-867, KF-8021, KF-869, and KF-861, all of which are provided by Shin-Etsu Chemical Co.

[0130] The amine-modified silicones having a pendent graft structure are formed from a linear polydimethylsiloxane backbone containing one or more organic amine side chains.

[0131] 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 pendent graft structure has a branched polydimethylsiloxane backbone comprising one or more organic amine side chains, and, optionally, one or more fatty alkyl side chains or polyether side chains as described above.

[0132] In some embodiments, the inkjet ink is substantially free of silicone having no amine functionality. Examples of such silicones include unmodified silicones (e.g., silicones having no side chains comprising non-siloxane functional groups) and modified silicones having only other non-amine functional groups, such as polyether-modified silicones (e.g., silicones having only polyether side chains), 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 free of silicone having no amine functionality. That is, the inkjet ink does not contain a silicone having no amine functionality. 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 free of silicone having no amine functionality, the amine-modified silicone can contain or include other functional groups, such as those listed above. In some embodiments in which the inkjet ink is free of silicone having no amine functionality, the amine-modified silicone does not contain or include other functional groups. That is, the inkjet ink is free of a silicone having no amine functionality, and the amine-modified silicone present is free of non-amine functional groups.

[0133] In some embodiments, the silicone (D) has a viscosity of at least 25 mm 2 / s, preferably at least 30 mm 2 / s, preferably at least 35 mm 2 / s, preferably at least 40 mm 2 / s, preferably at least 45 mm 2 / s, preferably at least 50 mm 2 / s, preferably at least 55 mm 2 / s, preferably at least 60 mm 2 / s, and at most 250 mm 2 / s, preferably at most 240 mm 2 / s, preferably at most 230 mm 2 / s, preferably at most 220 mm 2 / s, preferably at most 210 mm 2 / s, preferably at most 200 mm 2 / s, preferably at most 190 mm 2 / s, preferably at most 180 mm 2 / s, preferably at most 170 mm 2 / s, preferably at most 160 mm 2 / s, preferably at most 150 mm 2 / s, preferably at most 140 mm 2 / s, preferably at most 130 mm 2 / s, preferably at most 120 mm 2 / s, preferably at most 110 mm 2 / s.

[0134] In some embodiments, the amine functionality equivalent weight (FGEW) of the silicone (D) is preferably from 350 to 11,000 g / mol, preferably from 1,000 to 9,000 g / mol, preferably from 1,500 to 8,800 g / mol, preferably from 1,700 to 7,600 g / mol, preferably from 2,000 to 7,000 g / mol, preferably from 3,000 to 6,500 g / mol, preferably from 5,000 to 6,000 g / mol. The functionality equivalent weight refers to the weight of the amine-modified silicone containing one amine functionality of a molecular weight.

[0135] Suitable examples of amine-modified silicones that can be used in the disclosed inkjet inks include, but are not limited to, KF-865 (monoamino, viscosity 110 mm 2 / s, functionality equivalent weight (FGEW) = 5,000), KF-868 (monoamino, viscosity 90 mm 2 / s, FGEW = 8,800), KF-864 (monoamino, viscosity 1,700 mm 2 / s, FGEW = 3,800), KF-859 (diamino, viscosity 60 mm 2 / s, FGEW = 6,000), KF-393 (diamino, viscosity 70 mm 2 / s, FGEW = 350), KF-860 (diamino, viscosity 250 mm 2 / s, FGEW = 7,600), KF-880 (diamino, viscosity 650 mm 2 / s, FGEW = 1,800), KF-8004 (diamino, viscosity 800 mm 2 / s, FGEW = 1,500), KF-8002 (diamino, viscosity 1,100 mm 2 / s, FGEW = 1,700), KF-8005 (diamino, viscosity 1,200 mm 2 / s, FGEW=11,000), KF-867 (diamino, viscosity 1300 mm at 25°C 2 / s, FGEW=1,700), KF-8021 (diamino, viscosity 15,000 mm at 25°C 2 / s, FGEW=55,000), KF-869 (diamino, viscosity 1,500 mm at 25°C 2 / s, FGEW=3,800) and KF-861 (diamino, viscosity 3,500 mm at 25°C) 2 / s, FGEW=2,000), which are available from Shin-Etsu Chemical Co. In a preferred embodiment, the amine-modified silicone is KF-859.

[0136] The silicone (D) is preferably present 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 the total weight of the inkjet ink. In one embodiment, the silicone (D) is preferably 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 the total weight of the inkjet ink.

[0137] (E) pH adjuster

[0138] In some embodiments, the inkjet ink further comprises a pH adjuster (E). The pH adjuster can improve the solubility of the dye to achieve higher ink stability and improved printing results (higher color formation quality).

[0139] In a preferred embodiment, the pH adjuster (E) includes an amine. Preferred amines include alkylamines, alkoxyalkylamines, diamines, polyamines, and alkanolamines. Among these, alkanolamines are more preferred from the perspective of increasing the solubility of the dye in alcohol.

[0140] Alkanolamines are alkane-based compounds that contain both a hydroxyl group (-OH) and an amine group (primary, secondary, or tertiary amine). 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 at most 8 carbon atoms, at most 7 carbon atoms, at most 6 carbon atoms, or at most 5 carbon atoms. In preferred embodiments, the alkanolamine has 3 carbon atoms.

[0141] In preferred embodiments, the alkanolamine used in the inkjet inks herein has the following general formula II:

[0142]

[0143] wherein X, Y, and Z are independently selected from the group consisting of hydrogen; C1-C5 alkyl, preferably C2-C3 alkyl; and alkanol, preferably C2-C5 alkanol, more preferably C3-C4 alkanol; and at least one of X, Y, and Z is an alkanol group (an alkyl substituent bearing at least one hydroxyl group).

[0144] In some embodiments, one of X, Y, and Z is an alkanol group. In some embodiments, two of X, Y, and Z are alkanol groups. In some embodiments, all of X, Y, and Z are alkanol groups.

[0145] The alkyl chain of the alkanol group can comprise a branch for one or more alkanol groups. Alternatively, the alkyl chain of the alkanol group can be straight (containing no alkyl branches). In preferred embodiments, the alkanol group is based on a straight alkyl chain. Further, the carbon bearing the hydroxyl group in the alkanol group can be a primary carbon, a secondary carbon, or a tertiary carbon, preferably the carbon bearing the hydroxyl group is a primary carbon or a secondary carbon.

[0146] The alkanolamine can comprise 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 is hydrogen), or a tertiary amine group (i.e., all of X, Y, and Z are non-hydrogen). When an alkanolamine comprising a secondary amine group is employed, the two non-hydrogen substituents can be the same or different alkanol groups, preferably the same alkanol group, such as the case with diethanolamine. When an alkanolamine comprising a tertiary amine group is employed, the three non-hydrogen substituents can be the same or different alkanol groups, preferably the same alkanol group, such as the case with triethanolamine.

[0147] Examples of suitable alkanolamines 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-ethyldiethanolamine, 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-1,3-propanediol, 4-amino-1- butanol, 2-amino-1-butanol, sec-butanolamine, and di-sec-butanolamine, including various stereoisomers thereof and mixtures thereof. In preferred embodiments, the alkanolamine includes at least one selected from isopropanolamine, ethanolamine, propanolamine (3-amino-1-propanol), diethanolamine, and triethanolamine. In preferred embodiments, the alkanolamine includes isopropanolamine (1-amino-2-propanol).

[0148] In some embodiments, the pH adjuster (E) is present in the inkjet ink in an amount of preferably 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 ranging from 0.1 to 5 wt%, more preferably from 0.2 to 4 wt%, even more preferably from 0.5 to 2 wt%, even more preferably from 0.8 to 1.5 wt%, based on the total weight of the inkjet ink. In some embodiments, the weight ratio of rosin resin (A) to pH adjuster (E) ((A):(E)) is preferably in the 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.

[0149] (F) Additives

[0150] In some embodiments, the inkjet ink can include one or more additional ingredients or additives. These additional resins, adhesives, tackifiers, or glues can include, but are not limited to:

[0151] - terpene resins, such as resins based on monoterpene monomer units, e.g., the monoterpene can be a straight-chain monoterpene (e.g., myrcene, ocimene, etc.), a monocyclic monoterpene (e.g., limonene, γ-terpinene, a-phellandrene, β-phellandrene, terpinolene, etc.), or a bicyclic monoterpene (e.g., 3-carene, a-pinene, β-pinene, a-fenchene, camphene, etc.), including various stereoisomers thereof and mixtures thereof. Examples of terpene resins include, but are not limited to, PICCOLYTE A115, PICCOLYTE A125, PICCOLYTE A135, PICCOLYTE A135 PLUS, PICCOLYTE AO PLUS, PICCOLYTE A25, and PINOVARESIN 2495 (each made from high purity a-pinene), and PICCOLYTE S25 (made from high purity β-pinene), all of which are available from Pinova;

[0152] - terpene phenol resins, which have structural units of both a terpene and a phenol. Terpene phenol resins are copolymerization reaction products of one or more phenolic compounds with one or more terpenes. Terpene phenol resins include, but are not limited to, YS POLYSTER products available from Yasuhara Chemical Co. Ltd., such as YS POLYSTER U130, YS POLYSTER U115, YS POLYSTER T160, and YS POLYSTER T145, and DERTOPHENE products available from DRT, such as DERTOPHENE T, DERTOPHENE T105, DERTOPHENE T115, and DERTOPHENE T160;

[0153] - other phenolic resins (i.e., copolymers of a phenolic compound with formaldehyde), such as novolac resins, such as PHENOLITE TD-2131 and PHENOLITE TD-2090 available from DIC Corp.;

[0154] - polyamide resins, such as 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;

[0155] - epoxy resins, including sulfonamide-modified epoxy resins, such as AD-PRO MTS available from Rit-Chem;

[0156] - (meth)acrylate and styrene / (meth)acrylic resins, such as 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.;

[0157] - polyurethane resins, such as polyurethane resins formed from the reaction between (i) polyols, including but not limited to: ethylene glycol, propylene glycol, propanediol, butanediol, polyethylene glycol, polypropylene glycol, polytetrahydrofuran diol, 3-methyl-1,5-pentanediol, 1,9-nonanediol, polyester polyols (such as polyethylene glycol adipate diol, polyethylene glycol succinate diol, poly(3-methyl-1,5-pentanediol adipate) diol, poly(3-methyl-1,5-pentanediol terephthalate) diol, 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; such as PERMAX 200, PERMAX 202, and SANCURE 20025F available from Lubrizol;

[0158] - polyvinyl butyral resins, such as PIOLOFORM BN16 and MOWITAL B20H available from Kuraray America, Inc.;

[0159] - polyhydroxystyrene resins, such as poly(p-hydroxystyrene) from DuPont;

[0160] - vinyl resins, such as 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;

[0161] - formaldehyde resins, including sulfonamide-modified formaldehyde resins, such as p-toluenesulfonamide formaldehyde resins, melamine formaldehyde resins, sulfonamide-modified melamine formaldehyde resins;

[0162] - cellulose ester resins, such as cellulose acetate butyrate (CAB-551-0.01) available from Eastman;

[0163] - opacifying agents, examples of which can include, but are not limited to, titanium dioxide, zirconium silicate, zirconium oxide, tin oxide, cerium oxide, zinc oxide, aluminum oxide, silicon dioxide, kaolin, calcium carbonate, magnesium carbonate, calcium magnesium carbonate, barium carbonate, albite, potassium feldspar, nepheline, calcium silicate, mullite, wollastonite, and talc;

[0164] - 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;

[0165] - glycol ethers, such as 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 dimethyl ether, diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol diethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol mono n-propyl ether, and mixtures thereof;

[0166] - polyesters, sulfonated polyesters, gums, cellulose ethers, nitrocellulose resins, polymaleic anhydride, acetal polymers, styrene / butadiene copolymers, ketone aldehyde resins, and polyketone resins;

[0167] - anti-coking agents, stabilizers, humectants, safety tracers, other resins, adhesives, tackifiers, mastic agents, rust inhibitors, or other inkjet ink additives known to those of ordinary skill in the art;

[0168] - and the like, including mixtures thereof.

[0169] In one embodiment, the additive (F) can include a surfactant to supplement or replace the amine-modified silicone (D). Examples of surfactants include, but are not limited to:

[0170] - polysiloxanes, including organomodified silicones other than amine-modified silicones (D) (e.g., alkyl, aryl, and / or aralkyl-modified silicones), such as SILTECH C-32 available from Siltech Corporation; COATOSIL 1211C and 3573, both available from Momentive; KF-410 (aralkyl-modified polydimethylsiloxane) available from Shin-Etsu Chemical Co.; and BYK-322 and BYK-323 (aralkyl-modified poly(dimethylsiloxane-co-methylalkylsiloxane)), both available from BYK Additives & Instruments;

[0171] - 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.);

[0172] - polyether-modified silicones, including polyether-modified silicones that include block copolymers having a pendant graft structure formed from a linear or branched polydimethylsiloxane 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 dimethylsiloxane, unblocked, HLB = 10.0), KF-6015 (PEG-3 dimethylsiloxane, unblocked, HLB = 4.5), KF-6017 (PEG-10 dimethylsiloxane, unblocked, HLB = 4.5), and KF-6038 (lauryl PEG-9 polydimethylsiloxyethyl dimethylsiloxane, unblocked, HLB = 3.0), all available from Shin-Etsu Chemical Co., and BYK-307 (polyether-modified polydimethylsiloxane) available from BYK Additives & Instruments;

[0173] - fluoropolymers such as FC-4430 and FC-4432, available from 3M Company;

[0174] - photo-crosslinkable silicone acrylates or silicone polyether acrylates, such as TEGO RAD 2100, TEGO RAD 2200, TEGO RAD 2250, TEGO RAD 2300 (silicone polyether acrylates), all available from Evonik Industries, and BYK-UV 3500 and 3530 available from BYK;

[0175] - polyacrylates, including polyacrylate copolymers and crosspolymers, such as BYK-381 and BYK-361N (polyacrylate copolymers), both available from BYK, PEMULEN EZ-4U (acrylates / C10-C30 alkyl acrylate crosspolymer) and PEMULEN TR-2 (acrylic acid / C10-C30 alkyl acrylate crosspolymer), both available from Lubrizol;

[0176] - acetylenic glycol and acetylenic glycol-based gemini surfactants, such as SURFYNOL SEF and DYNOL surfactants available from Evonik Industries;

[0177] - polysiloxane-based gemini surfactants, such as TEGO TWIN 4100 available from Evonik Industries;

[0178] - nonionic polyethers, for example as a substrate wetting surfactant, such as TEGO WET 510 (hydrophilic polyether substrate wetting surfactant) available from Evonik Industries;

[0179] - 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;

[0180] - ethers, such as alkoxylated C1-C 22 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 (ethoxylated tridecanol), all available from Stepan, ethylene oxide / propylene oxide copolymers, alkoxylated alkyl phenols, and alkyl polyglycosides (APGs), such as those prepared from the reaction between a fatty alcohol and glucose;

[0181] - 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 thereof, monoglycerides, polyglycerol esters, esters of polyols, and sorbitol / sorbitol esters such as sorbitan monolaurate (e.g., EMASOL L-10V available from Kao) and polysorbate esters, including mono, di, or tri fatty acid esterified polysorbate esters such as TOXIMUL SEE-340 (polyoxyethylene (20) sorbitan trioleate) available from Stepan; and

[0182] - glycosides of fatty alcohols such as PLANTASENS NATURAL EMULSIFIER HE20 (cetearyl glucoside, sorbitan olivate) available from Clariant.

[0183] Any of the additives listed above (including surfactants) can be present in any of the inkjet inks of the present disclosure in 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 up to 10 wt%, up to 9 wt%, up to 8 wt%, up to 7 wt%, up to 6 wt%, up to 5 wt%, up to 4.5 wt%, up to 4 wt%, up to 3.5 wt%, up to 3 wt%, based on the total weight of the inkjet ink.

[0184] Alternatively, the inkjet ink can be free or substantially free of any of the additives or compounds listed above, including surfactants, meaning that the concentration of such additive or compound in the inkjet ink is 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%.

[0185] In some embodiments, the inkjet ink preferably contains substantially no terpene resin. In some embodiments, the inkjet ink preferably contains substantially no phenolic resin. In some embodiments, the inkjet ink preferably contains substantially no terpene phenolic resin. In alternative embodiments, the inkjet ink contains substantially no colorant (C), amine-modified silicone (D), surfactant, and / or pH adjuster (E). In one embodiment, the inkjet ink contains substantially no solvent having a Hildebrand solubility parameter equal to or greater than 11 cal 1 / 2 cm -3 / 2 In one embodiment, the inkjet ink contains substantially no rosin and modified rosin having an acid number equal to or greater than 22 mgKOH / g and / or a hydroxyl number greater than 40 mgKOH / g.

[0186] Manufacturing methods

[0187] Embodiments of the inkjet inks described herein can be prepared by any suitable technique known to one of ordinary skill in the art, for example, by combining the rosin resin (A) or modified rosin resin (A1) and any desired optional ingredients (e.g., colorant (C), amine-modified silicone (D), pH adjuster (E), and / or additive (F)) with a suitable solvent system (B) (including alcohol (B1) and co-solvent (B2)) in any order, and stirring, agitating, and / or homogenizing for an appropriate time at a temperature of 20 to 100 °C to form a homogeneous solution.

[0188] In one example, the inkjet ink can be made by first combining the rosin resin (A) with the alcohol (B1) and co-solvent (B2) and any optional resins, solvents, surfactants, or other additives in a container, and then stirring for at least 10 minutes. Then, the colorant (C) can be added as the last component and stirring continued, and then the solution is mixed for at least 10 minutes to obtain the inkjet ink. The resulting inkjet ink is then loaded into a print cartridge, such as a HP45Si printer cartridge produced by Hewlett Packard, a FUNAI TIJ cartridge produced by Funai Co., or some other print head suitable for use with solvent-based inks.

[0189] Performance

[0190] The inkjet inks disclosed herein have extended open time at a range of temperatures and humidities, for example, by the following measurement: print, expose the inkjet ink to air (open ink cartridge) for a period of time (e.g., 1 minute, 10 minutes, 30 minutes, 60 minutes, etc.), re-print the same image, and then compare the open re-printed image to the original image to determine if line loss / loss of line clarity has occurred in the fine line image. If no line loss or loss of clarity occurs within the time interval tested, the inkjet ink is rated as “good” for open at that time interval. If 1 to 10 line losses or a loss of clarity occurs within the time interval tested, but is not enough to significantly affect the clarity or legibility of the image, the inkjet ink is rated as “acceptable” for open at that time interval. If greater than 10 line losses or a significant loss of clarity and / or legibility occurs within the time interval tested, the inkjet ink is classified as “poor” for open at that time interval. A suitable inkjet ink is one that is capable of achieving an “acceptable” or “good” open classification after being open (i.e., exposed to air) for 30 seconds or more, preferably 1 minute or more, more preferably 10 minutes or more, even more preferably 30 minutes or more, yet even more preferably 60 minutes or more. Inkjet inks that are considered to have “acceptable” or “good” open classifications for longer periods of time are considered to have good “intermittent printing suitability.”

[0191] The inkjet inks disclosed herein can also have the characteristic of long run stability (also referred to as ink shelf life or print shelf life). To test the run stability of an inkjet ink, a fine line image (e.g., a barcode) can be printed (1 mm x 1 cm, fine line, single color bitmap) without interruption, printed continuously for many pages (e.g., 3,000 pages in a continuous printing operation), and the print quality can be assessed by visually inspecting certain pages (e.g., pages 1,000, 2,000, and 3,000) for nozzle absence throughout the printing operation. If no loss of lines / loss of line clarity occurs on the inspected pages, the inkjet ink is given a run stability rating of "G" (good) at that page. If 1-2 lines are lost / clarities are lost on the inspected pages, but not enough to significantly affect the clarity or readability of the fine line image, the inkjet ink is given a run stability rating of "A" (acceptable) at that page. If more than 2 lines are lost / clarities are lost on the inspected pages, the inkjet ink is given a run stability rating of "NG" (not good) at that page. In terms of run stability (the ability to remain dispersed / suspended and not settle / sediment and to not be improperly jetted), it is desirable to have an inkjet ink that maintains a "G" or "A" rating (preferably a "G" rating) when printing 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.

[0192] Printed article

[0193] The printed article of the present invention comprises a substrate and a dried form of the inkjet ink of the present invention disposed on the substrate.

[0194] The inkjet inks can be printed on a variety of substrates, including three-dimensional parts as well as flat sheets or webs provided 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 jetting distance capability are capable of forming printed images on complex three-dimensional substrates, such as radial, curved, jagged, corrugated, fluted, ruffled substrates, and / or substrates having a structured surface (e.g., a granular surface), all of which are well known difficult substrates due to the long distance the ink must travel to reach all portions of the complex surface. The printed articles can be suitable for the art, textile, packaging (e.g., food packaging, pharmaceutical packaging, etc.), lottery, direct mail, business forms, and publishing industries, examples of which include labels or tags, lottery tickets, publications, packaging (e.g., food packaging, pharmaceutical packaging, blister packaging, other various flexible packaging, etc.), folding cartons, rigid containers (e.g., plastic cups or tubs, glass containers, metal cans, bottles such as PET bottles, cans, and tubes), envelopes, corrugated board, point-of-sale displays, and the like. Particularly preferred printed articles are those having the inkjet ink in dried form disposed on complex three-dimensional portions of the printed article, for example, printed articles in which the printed image is on a fluted or crimped portion of a plastic container, or on the dished bottom of a metal can.

[0195] The inkjet inks can be printed on porous (or penetrable) substrates, examples of which include, but are not limited to, uncoated paper, wood, film, corrugated board (fluted paperboard / fiberboard), and fabric (including, but not limited to, woven fabric, nonwoven fabric, and foil laminated fabric).

[0196] The inkjet inks can also be printed on non-porous (or non-penetrable substrates), for example, various plastics, glass, metal (e.g., steel, aluminum, etc.), and / or non-penetrable paper (e.g., coated paper such as varnished coated paper), including, but not limited to, flat sheets or rolls of molded plastic or metal parts and plastic or metal film. 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), tri-acetate cellulose (TAC), polycarbonate, acrylonitrile butadiene styrene (ABS), polyacetal, polyvinyl alcohol (PVA), coated paper such as varnished coated paper, and metals such as steel and aluminum, and the like.

[0197] Method of forming a printed image

[0198] The method of the present invention for forming a printed image on a substrate comprises jetting the inkjet ink of the present invention onto a substrate with a thermal inkjet printhead and drying the inkjet ink.

[0199] By inkjet printing, a desired printed image is formed when a precise dot pattern is ejected from a droplet-generating device known as a printhead onto a print medium. The printhead has a precisely formed array of nozzles that are located on a nozzle plate and attached to an inkjet printhead substrate. The inkjet printhead substrate includes an array of firing chambers that receive inkjet ink in fluid communication with one or more ink reservoirs. Each firing chamber has a resistor element, known as a firing resistor, located opposite the nozzle to cause inkjet ink to pool between the firing resistor and the nozzle. Each resistor element is typically a pad of resistive material, for example, about 35 μm x 35 μm in size. The printhead is held and protected by an outer package known as a print cartridge or inkjet pen. Upon energizing a particular resistor element, a droplet of inkjet ink is expelled through the nozzle toward the print medium. The ejection of the ink droplet is typically under the control of a microprocessor whose signals are delivered to the resistor elements through electrical traces, thereby forming alphanumeric and other image patterns on the print medium. Because the nozzles are small, typically 10 μm to 40 μm in diameter, it is desirable to minimize clogged ink. In particular, because thermal inkjet (TIJ) printing uses an open atmospheric printhead design (the nozzle ejection orifice is open to the atmosphere and there is no valve seal at the orifice to allow pressurization of the ink), TIJ printing has always had poor performance during intermittent printing, especially in cold dry environments, where the open time (print idle time) causes the ink inside and around the nozzles to dry out prematurely.

[0200] The present disclosure provides a method of forming a printed image by jetting any of the inkjet inks of one or more embodiments of the present disclosure onto a substrate surface with a thermal inkjet printhead and drying the inkjet ink. The use of the inkjet inks described herein overcomes the problem of short open time (too fast solvent loss rate) typically associated with thermal inkjet processes at a range of temperatures and humidities.

[0201] Any drop-on-demand printhead known to those of ordinary skill in the art of inkjet printing can be used as the printing unit in the present method, including continuous printheads, thermal printheads, electrostatic printheads, and acoustic printheads, with thermal printheads (having thermal transducers) being preferred. Typical parameters, such as print resolution, print speed, printhead pulse heating temperature, drive voltage, and pulse length, can be adjusted according to the specifications of the printhead. Drop sizes of printheads typically suitable for use in the methods herein range from 2 to 80 pL, and drop frequencies range from 10 to 100 kHz, for example, by setting the drive voltage to 8.0 to 9.5 volts, the print speed to at most 300 feet / minute, the pulse heating temperature to 25 to 45 °C, and the pulse length to 0.7-2.5 microseconds, high quality printing can be obtained, although values higher or lower than these described can also be used and still obtain satisfactory printing. One non-limiting example of a printhead suitable for use in the methods herein is the HP45Si printer cartridge produced by Hewlett Packard or the FUNAI TIJ cartridge produced by Funai Co.

[0202] After jetting, the inkjet ink is dried. In some embodiments, external heat can be applied, for example by using a heater, to dry the jetted inkjet ink. However, it is preferred that no external heat be applied to promote drying or to increase the speed of drying. Thus, in preferred embodiments, drying is achieved by allowing the jetted 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, still even more preferably 10 seconds or less, without the use of an external heat source such as a heater. Drying times can increase or decrease based on ambient temperature and humidity. Furthermore, the methods of the present disclosure do not require energy curing (e.g., UV or e-beam curing). Once the jetted ink is deemed dry, further inkjet ink layers can be jetted, or any processing steps known to those of ordinary skill in the art can be performed as desired.

[0203] It should also be recognized that prior to jetting the inkjet ink, a substrate surface treatment such as corona treatment, room temperature plasma treatment, and flame treatment can optionally be employed in the methods herein to improve print article properties, such as ink adhesion. Parameters for such substrate surface treatments can vary widely depending on the substrate to be printed, the particular inkjet ink used, the printing method applied, and the desired properties and applications of the print article.

[0204] The following examples 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.

[0205] Example

[0206] Materials

[0207] EB Acetate is ethylene glycol monobutyl ether acetate and PM Acetate is propylene glycol methyl ether acetate, both of which are available from Eastman.

[0208] PINECRYSTAL KE-311 is a glyceryl hydrogenated rosin ester and PINECRYSTAL KE-359 is a pentaerythritol hydrogenated rosin ester, both of which are available from Arakawa Chemical Industries, Ltd.

[0209] PINECLEAR 4306A and PINEREZ 2308A are both pentaerythritol esters of stabilized rosin, both of which are available from Lawter. FILTREZ 3305 is a maleic acid modified rosin ester, also available from Lawter.

[0210] DERTOPHENE T105 is a terpene phenol aldehyde resin available from DRT.

[0211] PHENOLITE TD-2090 is a novolak resin available from DIC Corp.

[0212] JONCRYL 680 is an acrylic resin available from BASF.

[0213] VALIFAST BLACK 3830 is a colorant including Solvent Black 27, available from Orient Chemical Industries Co., Ltd.

[0214] KF-859 is an amine-modified silicone available from Shin-Etsu Chemical Co.

[0215] Inkjet ink embodiments

[0216] The inkjet ink examples are given in Table 1. The amounts of the components are expressed in weight percent based on the total weight (100%) of the inkjet ink.

[0217] * indicates that the example is a comparative example.

[0218] Preparation Method

[0219] The inks were obtained by mixing the rosin resin, organic solvent, and other ingredients (such as amine and surfactant) by a magnetic stir bar until completely dissolved. The dye was added to the mixture and stirred for 30 minutes. The results of printing using these inks are shown in the table below. The inks were then evaluated as described below.

[0220] Inkjet ink evaluation method

[0221] Print sample preparation

[0222] The inkjet ink examples were evaluated by a TIJ printer produced by HAS using a HP45Si printer cartridge produced by Hewlett Packard. The TIJ printer was installed in an EPL-3H temperature and humidity controlled cabinet produced by Espec.

[0223] Unsealing time evaluation

[0224] To evaluate unsealing time, the following printing conditions were utilized:

[0225] - Print substrate: plain (uncoated) paper

[0226] - Print resolution: 300 dpi * 300 dpi (vertical * horizontal)

[0227] - Print speed: 7 m / min

[0228] - Pulse width: 1.8 μs

[0229] - Voltage: 8.6 V

[0230] - Pulse heating: OFF

[0231] - Print image: 100% duty cycle (monochrome bitmap) (see, e.g., FIGS. 1A-1C ). The image was 0.5 inches high and 2.7 inches long.

[0232] - Print environment: 10°C (50°F) at 30% relative humidity, or 35°C (95°F) at 85% relative humidity.

[0233] An image consisting of a sequence of numbers is printed to confirm that there are no missing or unclear lines in the printed image (indicating clogged or missing nozzles). After confirmation, the printhead is left unsealed for a specified time (1 minute, 3 minutes, 5 minutes, 10 minutes, 15 minutes, 30 minutes, 45 minutes, or 60 minutes), and the same image is reprinted. The reprinted image is inspected (after the specified time interval) to determine if line loss / loss of line sharpness occurs. If no line loss / loss of line sharpness occurs, the inkjet ink is given an unsealing rating of "Good" for that time interval. If 1-10 lines are lost during the test time interval, or if sharpness is lost, but not enough to significantly affect the sharpness or readability of the image during the test time interval, the inkjet ink is given an unsealing rating of "Acceptable" for that time interval. If more than 10 lines are lost during the test time interval, or if there is a significant loss of sharpness and / or readability, the inkjet ink is classified as "Poor" for that time interval. Suitable / desirable inkjet inks are those that achieve an "acceptable" or "good" opening classification after opening (ie, exposure to air) at each testing time interval and environmental condition.

[0234]

[0235]

[0236]

[0237]

[0238] Inkjet ink properties

[0239] As can be seen from Table 2, rosin resins with acid values ​​less than 22 mgKOH / g and hydroxyl values ​​less than 40 mgKOH / g, ethanol, and Hildebrand solubility parameters less than 11 cal 1 / 2 cm -3 / 2 The combination of co-solvents provided significant results in terms of operational stability and decapping time at different temperatures and humidities (Examples 1-2 and 10-16). In contrast, the inkjet ink formulated with a rosin resin having an acid value of less than 22 mgKOH / g but a hydroxyl value of 43 mgKOH / g, as in Example 5, showed poor decapping behavior. The inkjet inks formulated with a rosin resin having an acid value greater than 22 mgKOH / g in Examples 3 and 4 showed acceptable decapping performance at 35°C and 85% humidity, but the performance of these inks was poor under cooler and dry conditions of 10°C and 30% humidity. The inkjet inks formulated with 2-propanol as a co-solvent had a Hildebrand solubility parameter greater than 11 cal 1 / 2 cm -3 / 2 , also exhibited poor unsealing performance (Example 17).

[0240] With respect to the amount of rosin resin, it was found that excellent unsealing behavior was provided when loaded in the range of 1 to 5 wt%, while the co-solvent concentration was in the range of 2.5 to 10 wt% (Examples 1-2 and 10-16).

Claims

1. An inkjet ink, in, include: (A) rosin resin having an acid value of less than 22 mgKOH / g and a hydroxyl value of less than 40 mgKOH / g; (B1) alcohol; and (B2) a cosolvent having a Hildebrand solubility parameter of less than 11 cal 1 / 2 cm -3 / 2 , The weight ratio of the cosolvent (B2) to the rosin resin (A) (B2): (A) is 1:1 to 10:

1.

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

3. The inkjet ink according to claim 1, wherein The rosin resin (A) includes a modified rosin resin (A1).

4. The inkjet ink according to claim 3, wherein The modified rosin resin (A1) includes rosin ester.

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

6. The inkjet ink according to claim 1, wherein The alcohol (B1) is present in an amount of 75 to 90 wt %, based on the total weight of the inkjet ink.

7. The inkjet ink according to claim 1, wherein The alcohol (B1) includes at least one selected from the group consisting of methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-pentanol, 3-pentanol, and tert-pentanol.

8. The inkjet ink according to claim 1, wherein The alcohol (B1) includes ethanol.

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

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

11. The inkjet ink according to claim 1, wherein Also included are (C) colorants.

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

13. The inkjet ink according to claim 1, wherein Also included are (D) silicones.

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

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

16. The inkjet ink according to claim 15, wherein The pH adjuster (E) includes amines.

17. The inkjet ink according to claim 16, wherein The amines include alkanolamines.

18. A printed product, wherein: include: 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, in, include: spraying the inkjet ink of claim 1 onto the substrate using a thermal inkjet print head; as well as The inkjet ink is allowed to dry.

Images