Dioxolane and terpene resin-based inkjet ink

Abstract

An inkjet ink comprising (A1) a terpene resin, (B) a solvent system containing (B1) dioxolane, and (C) a colorant containing a metal complex azo dye, the inkjet ink being characterized by an extended decap time and excellent adhesion to a wide variety of substrates, a printed matter containing the inkjet ink in a dried form, and a method of forming a printed image using a thermal inkjet print head are also provided.

Description

Technical Field

[0001] The present invention relates to a solvent-based inkjet ink, specifically, an inkjet ink in which (A1) a terpene resin, (B) a solvent-based system containing (B1) dioxolane, and (C) a colorant containing a metal complex azo dye are blended.

Background Art

[0002] The description of "Background Art" provided herein is for the purpose of generally presenting the context of the present disclosure. The research of the inventors within the scope described in this background art section, and aspects of the description that may not be considered prior art at the time of filing, are not admitted as prior art to the present invention, either explicitly or implicitly.

[0003] Thermal inkjet (TIJ) printing is a desirable technology for printing, coding, and marking because it provides high printing resolution at a lower cost than competing technologies such as continuous inkjet (CIJ) methods. In the thermal inkjet printing process, the print cartridge contains a series of small chambers, each chamber contains a heater, and ink droplets are generated from the thermal evaporation of the ink solvent. In the ejection process, a resistor is rapidly heated to generate vapor bubbles (which is the origin of the term "bubble jet"), and then droplets are ejected from the orifice. This process is extremely efficient and reproducible, and modern TIJ printheads for industrial graphics applications can generate uniform droplets with a volume of 4 pL or less at a frequency of 36 kHz or higher.

[0004] However, for industrial marking and industrial coding, it is often necessary to print essential information such as personal information, labels, codes, dates (e.g., expiration dates), and traceability information (e.g., manufacturing lots) onto substrates with complex surfaces, such as substrates that are radial, curved, serrated, corrugated, grooved, and / or edged, or onto a wide variety of substrates, such as porous and non-porous substrates, or substrates formed from materials having various physicochemical properties.

[0005] Thermal inkjet printing can have problems with low reliability after periods of inactivity. For example, some inkjet inks suffer from short decap times due to solvent loss caused by long-term exposure to air in uncapped printheads, which leads to clogging / plugging of the printhead nozzles, and thus unreliable inkjetting and image quality degradation over time.

[0006] A solvent-based inkjet ink manufactured using a specific combination including a binder resin, a volatile organic solvent or solvent mixture containing dioxolane, and a colorant. For example, Patent Document 1 discloses an inkjet ink containing dioxolane and a colorant that can be Solvent Black 27, but this lacks a resin and thus does not have sufficient adhesion properties.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0008] From the foregoing viewpoints, there is a need for an inkjet ink with an extended decap time that maintains advantageous printing characteristics over long periods of ink use and strongly adheres to a large number of substrates.

[0009] Accordingly, one object of the present invention is to provide a novel inkjet ink that meets these criteria.

[0010] Another object of the present disclosure is to provide a novel printed matter including a dried form of the inkjet ink.

[0011] Another object of the present disclosure is to provide a novel method for forming a printed image on a substrate by applying and drying an inkjet ink on the substrate.

Means for Solving the Problems

[0012] These and other objects will become apparent in the following detailed description, but the inventors' discovery that a combination of a terpene resin, dioxane, and a colorant containing a metal complex azo dye provides an inkjet ink characterized by an extended decap time, excellent printing life, and excellent adhesion to various substrates has been achieved.

[0013] Accordingly, the present invention provides the following. 1. An inkjet ink comprising (A1) a terpene resin, (B) a solvent system containing (B1) dioxolane, and (C) a colorant containing a metal complex azo dye. 2. The inkjet ink according to (1), wherein the terpene resin (A1) is present in an amount of 0.1 to 10% by weight based on the total weight of the inkjet ink. 3. The inkjet ink according to (1) or (2), wherein the terpene resin (A1) is a homopolymer produced from α-pinene. 4. The inkjet ink according to any one of (1) to (3), wherein the dioxolane (B1) is present in an amount of 2 to 98% by weight based on the total weight of the inkjet ink. 5. The inkjet ink according to any one of (1) to (4), wherein the solvent system (B) further includes an alcohol solvent (B2). 6. The alcohol solvent (B2) is present in an amount of 0.5 to 60% by weight based on the total weight of the inkjet ink, the inkjet ink according to (5). 7. The weight ratio ((B1):(B2)) of dioxolane (B1) to the alcohol solvent (B2) is 0.25:1 to 30:1, the inkjet ink according to (5) or (6). 8. The weight ratio ((B1):(A1)) of dioxolane (B1) to the terpene resin (A1) is 20:1 to 250:1, the inkjet ink according to any one of (1) to (7). 9. The solvent system (B) substantially does not contain methyl ethyl ketone, the inkjet ink according to any one of (1) to (8). 10. The solvent system (B) does not contain methyl ethyl ketone, the inkjet ink according to (9). 11. The metal complex azo dye is a metal complex including a metal center and (E)-1-((2-methoxy-5-nitrophenyl)diazenyl)naphthalene-2-ol or its deprotonated form, demethylated form, deprotonated and demethylated form, tautomer, or stereoisomer, the inkjet ink according to any one of (1) to (10). 12. The metal center is a chromium ion, the inkjet ink according to (11). 13. The colorant (C) is present in an amount of 0.5 to 20% by weight based on the total weight of the inkjet ink, the inkjet ink according to any one of (1) to (12). 14. Further includes (A2) terpene phenol resin, the inkjet ink according to any one of (1) to (13). 15. The terpene phenol resin (A2) is present in an amount of 0.01 to 10% by weight based on the total weight of the inkjet ink, the inkjet ink according to (14). 16. Further includes (D) surfactant, the inkjet ink according to any one of (1) to (15). 17. The inkjet ink according to (16), wherein the surfactant (D) is present in an amount of 0.01 to 5% by weight based on the total weight of the inkjet ink. 18. The inkjet ink according to any one of (16) or (17), wherein the surfactant (D) is a silicone acrylate copolymer. 19. A printed matter comprising a substrate and a dried form of the inkjet ink according to any one of (1) to (18) disposed on the substrate. 20. A method of forming a printed image on a substrate, the method comprising applying the inkjet ink according to any one of (1) to (18) onto the substrate using a thermal inkjet print head, and drying the inkjet ink.

[0014] The foregoing paragraphs are provided as a general introduction and are not intended to limit 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.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Mode for Carrying Out the Invention

[0016] In the following description, it should be understood that other embodiments may be utilized and structural and operational changes may be made without departing from the scope of the embodiments disclosed herein.

[0017] The phrase "substantially free of" means that, unless otherwise specified, the amount of a particular component in the inkjet ink is less than 1% by weight, preferably less than 0.5% by weight, more preferably less than 0.1% by weight, even more preferably less than 0.05% by weight, and still even more preferably 0% by weight, based on the total weight of the inkjet ink.

[0018] As used herein, the term "optional" or "optionally" means that the subsequently described event(s) may or may not occur, or that the subsequently described component(s) may or may not be present (e.g., 0% by weight).

[0019] As used herein, the term "alkyl", unless otherwise specified, refers to a straight-chain, branched-chain 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 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, etc., including but not limited to 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-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, norbornyl, and adamantyl.

[0020] As used herein, the term "fatty" refers to a compound having a long-chain (straight-chain) hydrophobic moiety composed of hydrogen and generally 8 to 22 carbon atoms, which may be fully saturated or partially unsaturated.

[0021] As used herein, the term "aryl" refers to an aromatic group containing only carbon in the aromatic ring(s), e.g., phenyl, biphenyl, naphthyl, anthracenyl, etc.

[0022] As used herein, the term "arylalkyl" refers to a linear, branched, or cyclic alkyl moiety (as defined above) 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.

[0023] As used herein, the term "(meth)acrylate" is used to refer to both acrylate groups and methacrylate groups. In other words, this term should be read as if "meth" were optional. Further, the term "(meth)acrylate" is generally used to refer to both acrylic acid compounds and acrylic acid ester compounds.

[0024] Throughout this 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), and is also referred to as the standard boiling point unless otherwise specified.

[0025] As used herein, the term "decapping behavior" refers to the ability of an inkjet ink to be readily ejected from a print head when exposed to air for an extended period of time. The "decap time" of an inkjet ink is measured as the amount of time that the cap of an inkjet print head can be left off before the nozzles of the printer will no longer fire properly, potentially due to clogging or jamming upon resumption of printing. Generally, the nozzle(s) may become clogged (i.e., obstructed, slowed down) or jammed (i.e., blocked, substantially or completely closed) by a viscous plug formed within the nozzle(s) as a result of solvent loss, ink crusting, and / or cogelation of various ink components within and / or around any of the nozzles. When a nozzle becomes clogged, the ink droplets ejected through the orifice of the nozzle may be directed in the wrong direction, potentially affecting print quality. When the orifice becomes jammed, it is substantially or completely blocked. As a result of a clogged nozzle, ink droplets are unable to pass through the affected nozzle. Thus, the criterion for measuring nozzle firing failure is that the direction of the ink through the orifice of the nozzle is at least somewhat incorrect or completely blocked, which can be measured by visually inspecting the printed image.

[0026] The term "netting" refers to a printing defect characterized by the detachment of an ink film from a portion of a substrate due to incompatibility between the inkjet ink and the surface of the substrate. Netting often results in the generation of an image with an "orange peel" effect or a "pinhole" effect.

[0027] Inkjet ink The present disclosure is directed to an inkjet ink that has appropriate physical and chemical stability at both ambient temperature and the operating temperature of the print head, is reliably ejected, exhibits good adhesion to porous and non-porous substrates, dries quickly after being applied to the substrate, and has an extended decap time.

[0028] The inkjet ink of the present disclosure generally includes the following components: (A1) a terpene resin, (B) a solvent system containing (B1) dioxolane, and (C) a colorant containing a metal complex azo dye.

[0029] The inkjet ink of the present disclosure may also optionally include one or more of (A2) a terpene phenol resin, (B2) an alcohol solvent as part of the solvent system (B), (D) a surfactant, and (E) an additive.

[0030] (A) Resin(s) The terpene resin (A1) is incorporated into the inkjet ink of the present disclosure. Typically, the terpene resin (A1) is preferably at least 0.1% by weight, preferably at least 0.2% by weight, preferably at least 0.3% by weight, preferably at least 0.4% by weight, preferably at least 0.5% by weight, preferably at least 0.6% by weight, more preferably at least 0.7% by weight, still more preferably at least 0.75% by weight, still more preferably at least 0.8% by weight, based on the total weight of the inkjet ink, and is preferably up to 10% by weight, preferably up to 9% by weight, preferably up to 8% by weight, preferably up to 7% by weight, preferably up to 6% by weight, preferably up to 5% by weight, more preferably up to 4% by weight, still more preferably up to 3% by weight, still more preferably up to 2.5% by weight.

[0031] The terpene resin (A1) of the present disclosure refers to an oligomer or polymer having structural units derived from polymerizable terpene(s) preferably at least 95% by weight, preferably at least 96% by weight, more preferably at least 97% by weight, more preferably at least 98% by weight, more preferably at least 99% by weight, still more preferably at least 99.5% by weight, still more preferably 100% by weight, based on all the structural units (100% by weight) of the terpene resin (A1).

[0032] The constitutional units other than terpenes that make up the terpene resin (A1) may be any units copolymerizable with terpenes, but are not phenols. That is, in the present invention, the terpene resin (A1) is not a terpene phenol resin.

[0033] Terpenes have a basic skeleton (C5H8)p, where p is a positive integer indicating the number of isoprene units joined head-to-tail in succession. For example, hemiterpenes (p = 1) have a C5H8 skeleton, monoterpenes (p = 2) have a C10H16 skeleton, sesquiterpenes (p = 3) have a C15H24 skeleton, and so on.

[0034] In some embodiments, the terpene resin (A1) is based on monoterpene monomer units. Monoterpenes can be linear monoterpenes (e.g., myrcene, ocimene, etc.), monocyclic monoterpenes (e.g., limonene, γ-terpinene, α-farnesene, β-farnesene, terpinolene, etc.), or bicyclic monoterpenes (e.g., 3-carene, α-pinene, β-pinene, α-phellandrene, camphene, etc.) (including their various stereoisomers), and mixtures thereof. In some embodiments, the monoterpene is a monocyclic monoterpene, and limonene is particularly preferred. In preferred embodiments, the monoterpene is a bicyclic monoterpene, particularly preferably 3-carene, α-pinene, β-pinene, and camphene, more preferably α-pinene and / or β-pinene, and even more preferably α-pinene.

[0035] A preferred inkjet ink is one containing a terpene resin (A1) produced from the polymerization or oligomerization of α-pinene. As is known to those skilled in the art, such a terpene resin can be easily obtained, for example, by the catalytic polymerization / oligomerization (in solution) of α-pinene monomers, and this monomer is further typically derived from the fractional distillation of rubber and sulfated turpentine oil obtained from pines such as Pistacia terebinthus, Pinus pinaster, Pinus halepensis, Pinus massoniana, Pinus merkusii, Pinus palustris, Pinus taeda, and Pinus ponderosa.

[0036] In a preferred embodiment, the terpene resin (A1) is a homopolymer produced from α-pinene, having a α-pinene content (structural units derived from α-pinene) of preferably at least 95% by weight, preferably at least 96% by weight, preferably at least 97% by weight, preferably at least 98% by weight, preferably at least 99% by weight, more preferably at least 99.5% by weight, even more preferably 99.9% by weight, and still even more preferably 100% by weight, based on all the structural units (100% by weight) of the terpene resin (A1). The terpene resin (A1) of the present disclosure may contain a small amount of other structural units other than the structural units derived from α-terpene monomers, but the amount of other (e.g., non-terpene-based) structural units is preferably less than 5% by weight, preferably less than 3% by weight, preferably less than 1% by weight, more preferably less than 0.5% by weight, even more preferably less than 0.1% by weight, and still even more preferably 0% by weight, based on all the structural units (100% by weight) of the terpene resin (A1).

[0037] In some embodiments, the terpene resin (A1) is a homopolymer produced from β-pinene, preferably having a β-pinene content (structural units derived from β-pinene) of at least 95 wt%, preferably at least 96 wt%, preferably at least 97 wt%, preferably at least 98 wt%, preferably at least 99 wt%, more preferably at least 99.5 wt%, even more preferably at least 99.9 wt%, and still even more preferably 100 wt% based on all the structural units (100 wt%) of the terpene resin (A1). The terpene resin (A1) of the present disclosure may contain a small amount of other structural units other than the structural units derived from β-terpene monomers, but the amount of other (e.g., non-terpene-based) structural units is preferably less than 5 wt%, preferably less than 3 wt%, preferably less than 1 wt%, more preferably less than 0.5 wt%, even more preferably less than 0.1 wt%, and still even more preferably 0 wt% based on all the structural units (100 wt%) of the terpene resin (A1).

[0038] Both the polymer form and the oligomer form of the terpene resin (A1) can be used herein, including their combinations. Typically, the terpene resin (A1) used herein preferably has a number average molecular weight (Mn) of at least 330 g / mol, preferably at least 340 g / mol, preferably at least 400 g / mol, preferably at least 450 g / mol, preferably at least 500 g / mol, preferably at least 550 g / mol, preferably at least 600 g / mol, more preferably at least 650 g / mol, even more preferably at least 700 g / mol, and still even more preferably at least 750 g / mol, and preferably up to 1500 g / mol, preferably up to 1300 g / mol, preferably up to 1100 g / mol, preferably up to 1000 g / mol, more preferably up to 900 g / mol, even more preferably up to 800 g / mol, and still even more preferably up to 790 g / mol.

[0039] The terpene resin (A1) can be in solid or liquid form at room temperature. When the terpene resin (A1) used in this specification is in solid form, it can be classified based on its softening point (SP), for example, according to the ring and ball method. The ring and ball softening point is defined as the temperature at which the disc of the sample held in a horizontal ring is pushed down by a distance of 1 inch (25.4 mm) under the weight of a steel ball while the sample is heated at a predetermined rate in a glycerol bath. For example, the ring and ball softening point can be determined in accordance with JIS B7410, which is hereby incorporated by reference in its entirety. Measuring device: Automatic ring and ball softening point; Testing machine: ASP-MGK2 (manufactured by MEITECH Company Ltd.); Heating rate: 5 °C / min; Starting temperature of heating: 40 °C; Measuring solvent: Glycerol. Terpene resins (A1) having a wide range of softening points, for example, preferably at least 20 °C, preferably at least 22 °C, and preferably up to 50 °C, preferably up to 45 °C, preferably up to 40 °C, more preferably up to 35 °C, even more preferably up to 30 °C, still even more preferably up to 28 °C, can be used in this specification. In a preferred embodiment, the terpene resin (A1) has a softening point of at least 20 °C, preferably at least 22 °C, more preferably at least 24 °C, and up to 50 °C, preferably up to 45 °C, preferably up to 40 °C, more preferably up to 35 °C, even more preferably up to 30 °C, still even more preferably up to 28 °C.

[0040] The bromine value is the amount of bromine (Br2) in grams absorbed by a 100-gram sample and is an indicator of the unsaturation of the sample. In some embodiments, the terpene resin (A1) used in the inkjet ink preferably has a bromine value of at least 12, preferably at least 15, preferably at least 19, preferably at least 22, more preferably at least 25, even more preferably at least 26, and still even more preferably at least 27, and preferably up to 35, preferably up to 34, preferably up to 33, more preferably up to 32, even more preferably up to 31, and still even more preferably up to 30. However, terpene resins (A1) having a bromine value above or below these values (e.g., hydrogenated terpene resins (A1)) can also be used in the disclosed inkjet inks.

[0041] One type of terpene resin (A1) or a combination of two or more types of terpene resins (A1) can be incorporated into the inkjet ink of the present disclosure. Examples of terpene resins (A1) that can be used alone or in combination in the inkjet inks of this specification include PICCOLYTE A115 (Globular SP = 112 - 118 °C, bromine value = 31.5), PICCOLYTE A125 (Globular SP = 122 - 128 °C, bromine value = 31.5), PICCOLYTE A135 (Globular SP = 132 - 138 °C, bromine value = 27), PICCOLYTE A135 PLUS (Globular SP = 132 - 138 °C), PICCOLYTE AO PLUS (oligomer, liquid), PICCOLYTE A25 (Globular SP = 22 - 28 °C), and PINOVA RESIN 2495 (Globular SP = 132 - 138 °C, bromine value = 27), all available from Pinova and each produced from high-purity α-pinene, as well as PICCOLYTE S25 (produced from high-purity β-pinene, Globular SP = 22 - 28 °C, bromine value 19) available from Pinova. However, the invention is not limited thereto. A particularly preferred terpene resin (A1) for use in the disclosed inkjet inks is PICCOLYTE A25.

[0042] When terpene resin (A1) is used in combination with a colorant containing dioxolane (B1) and a metal complex azo dye, it has been found to provide excellent decap time, operating stability (ink life), and adhesion. Without being bound by theory, terpene resin (A1) forms a thin "film" or "coating" cover within the print head nozzle, thereby generating a temporary seal that suppresses or reduces solvent loss during the non-operating period, improving the decap behavior and / or operating stability of the inkjet ink. However, it is considered that the "film" or "coating" can be easily broken when the printing operation is resumed.

[0043] The formation of such a "film" or "coating" may be advantageous for maintaining high performance over a wide range of decap times. Such advantages may be due to the rapid formation of this "film" or "coating". Surprisingly, in the evaluation of the decap time, the shorter the time, for example, 10 minutes compared to 60 minutes, the more difficult it is to obtain good results. This may be related to the fact that for a wide variety of ink formulations, the decap time required to completely form a thin "film" or "coating" by the terpene resin is long. This "film" or "coating" of the nozzle is easily destroyed by the impact of the resumption of ejection. In contrast, when the decap time is short, other ink formulations cannot form this thin "film" or "coating" and can only be in a highly viscous liquid state. Therefore, since the impact at the resumption of ejection is mitigated and the formation of droplets becomes incomplete, insufficient ink performance occurs. On the other hand, the ink of the present disclosure can form a completely thin "film" or "coating" even in a short time such as 30 seconds, resulting in excellent decap performance of the ink over a wide range of decap times. This rapid "film" or "coating" formation behavior is considered to result from an appropriate interaction between terpene resin (A1), the solvent system, particularly dioxolane (B1), and the colorant (C), particularly the metal complex azo dye.

[0044] In addition to the terpene resin (A1), the terpene phenol resin (A2) may optionally be incorporated into the inkjet ink disclosed herein. When used, the terpene phenol resin (A2) is preferably at least 0.01% by weight, preferably at least 0.025% by weight, preferably at least 0.05% by weight, preferably at least 0.075% by weight, preferably at least 0.1% by weight, preferably at least 0.15% by weight, at least 0.2% by weight, preferably at least 0.25% by weight, preferably at least 0.3% by weight, preferably at least 0.35% by weight, preferably at least 0.4% by weight, preferably at least 0.45% by weight, preferably at least 0.475% by weight, more preferably at least 0.5% by weight, and preferably up to 10% by weight, preferably up to 9% by weight, preferably up to 8% by weight, preferably up to 7% by weight, preferably up to 6% by weight, preferably up to 5% by weight, more preferably up to 4% by weight, even more preferably up to 3% by weight, still even more preferably up to 2% by weight, still even more preferably up to 1% by weight, still even more preferably up to 0.8% by weight, based on the total weight of the inkjet ink. Preferably, the amount (in % by weight) of the terpene phenol resin (A2) is not more than the amount of the terpene resin (A1) in the inkjet ink when the terpene phenol resin (A2) is used. In some embodiments, the inkjet ink is substantially free of the terpene phenol resin (A2).

[0045] The terpene phenol resin (A2) is a copolymerization reaction product by alkylation of one or more phenol compounds and one or more terpenes. As known to those skilled in the art, such resins can be readily obtained by copolymerizing a phenol compound and a terpene monomer under the catalytic action of a catalyst such as a strong acid, a metal salt having a condensation effect, bleaching earth, a Friedel-Crafts catalyst or a strong Lewis acid (e.g., boron trifluoride).

[0046] The terpene phenol resin (A2) of the present disclosure may contain a small amount of structural units other than the structural units derived from the phenol compound and the structural units derived from the terpene, but the amount of other (for example, non-phenolic and non-terpenoid) structural units is preferably less than 5% by weight, preferably less than 4% by weight, preferably less than 3% by weight, preferably less than 2% by weight, more preferably less than 1% by weight, even more preferably less than 0.5% by weight, and still even more preferably 0% by weight based on the total structural units (100% by weight) of the terpene phenol resin (A2).

[0047] The terpene phenol resin (A2) can be formed using any terpene having at least one olefinic double bond that can be alkylated by a phenol compound. In some embodiments, the terpene phenol resin (A2) is formed using a monoterpene monomer unit. The monoterpene can be a linear monoterpene (e.g., myrcene, ocimene, etc.), a monocyclic monoterpene (e.g., limonene, γ-terpinene, α-felandrene, β-felandrene, terpinolene, etc.), or a bicyclic monoterpene (e.g., 3-carene, α-pinene, β-pinene, α-phellandrene, camphene, etc.) (including their various stereoisomers), and mixtures thereof. In some embodiments, the monoterpene is a monocyclic monoterpene, and limonene is particularly preferred. In a preferred embodiment, the monoterpene is a bicyclic monoterpene, particularly preferably 3-carene, α-pinene, β-pinene, and camphene, more preferably α-pinene and / or β-pinene.

[0048] A phenolic compound has at least one hydroxyl group directly bonded to a phenyl ring. If the phenolic compound has at least two replaceable hydrogen atoms at the ortho and / or para positions relative to at least one hydroxyl group, then all monohydric or polyhydric phenolic compounds are useful for the preparation of the terpene phenolic resin (A2) described herein. That is, the phenolic compound should be capable of being polyalkylated (e.g., bisalkylated) with terpene(s), and thus should have at least two available ortho / para positions relative to at least one hydroxyl group for alkylation.

[0049] In a preferred embodiment, the phenolic compound is phenol, which can be considered the parent unsubstituted phenolic compound (i.e., it contains one hydroxyl group directly bonded to the phenyl ring and has no other substitutions). Alternatively, the phenolic compound may be substituted at up to three positions in addition to the phenolic hydroxyl group, where one, two, or three of the aromatic hydrogens of phenol are each substituted with the same number of substituents (each independently selected from a hydroxyl group, preferably a C1-C22 alkyl group, preferably a C2-C18 alkyl group, more preferably a C3-C12 alkyl group, even more preferably a C4-C9 alkyl group, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, a C1-C22 alkoxy group, preferably a C2-C12 alkoxy group, more preferably a C3-C6 alkoxy group, such as methoxy, ethoxy, and isopropoxy, an aryl group, an arylalkyl group, such as a benzyl group, and a halo group, such as chlorine, bromine, fluorine, and iodine).

[0050] Specific examples of the substituted phenol compounds include o-cresol, m-cresol, p-cresol, 2,5-xylenol, 2,3-xylenol, 3,4-xylenol, 3,5-xylenol, 2,3,5-trimethylphenol, isopropylphenol (e.g., 4-isopropylphenol), tert-butylphenol (e.g., 4-tert-butylphenol), amylphenol (e.g., 4-tert-amylphenol), heptylphenol (e.g., 4-heptylphenol), octylphenol (e.g., o-octylphenol, p-octylphenol, etc.), nonylphenol (e.g., 4-(2,4-dimethylheptan-3-yl)phenol), decylphenol, dodecylphenol, bisphenol, e.g., diphenylolpropane (bisphenol-A), phenylphenol (e.g., 3-phenylphenol), cumylphenol, mequinol, benzyloxyphenol, guaiacol, ethoxyphenol (e.g., 4-ethoxyphenol), and polyhydric phenol compounds, e.g., resorcinol, pyrogallol, catechol, and p-hydroquinone (including mixtures of any two or more of the above), but are not limited thereto. Condensed ring phenols such as naphthol (e.g., 1-naphthol, 2-naphthol, etc.) and similar compounds are also included. The preferred terpene phenol resin (A2) is formed from the copolymerization of phenol and one or more of α-pinene, β-pinene, and limonene.

[0051] The molecular weight of the terpene phenol resin (A2) can vary depending on the monomers used and the reaction conditions, among many other factors, but typically, preferably at least 400 g / mol, preferably at least 500 g / mol, more preferably at least 600 g / mol, even more preferably at least 700 g / mol, and up to 3000 g / mol, preferably up to 2500 g / mol, more preferably up to 2000 g / mol, even more preferably up to 1500 g / mol, and still even more preferably up to 1000 g / mol in weight average molecular weight (Mw) of the terpene phenol resin (A2) is used.

[0052] The terpene phenol resin (A2) can be classified based on its softening point (SP), for example, according to the ring and ball softening point method described previously (for example, in accordance with JIS B7410, which is hereby incorporated by reference in its entirety). In some embodiments, the terpene phenol resin (A2) preferably has a softening point of at least 60°C, preferably at least 80°C, preferably at least 90°C, preferably at least 100°C, preferably at least 105°C, more preferably at least 110°C, even more preferably at least 115°C, still even more preferably at least 120°C, and preferably up to 160°C, preferably up to 155°C, preferably up to 150°C, preferably up to 145°C, preferably up to 140°C, more preferably up to 135°C, even more preferably up to 130°C, still even more preferably up to 125°C.

[0053] The hydroxyl value (OHV) is defined as the number of milligrams of potassium hydroxide required to neutralize acetic acid incorporated when acetylating 1 gram of a chemical substance containing free hydroxyl groups. Thus, the hydroxyl value, or measure of the relative hydroxyl group content of the terpene phenol resin (A2), is directly correlated with the content of phenolic compound(s) in the terpene phenol resin (A2), and a higher hydroxyl value indicates a higher incorporation of phenolic compounds (and a lower terpene incorporation) into the copolymer. The hydroxyl value can be determined in accordance with Japanese Industrial Standard JIS K0070:1992 "Test Methods for Acid Value, Saponification Value, Ester Value, Iodine Value, Hydroxyl Value and Unsaponifiable Matter of Chemical Products".

[0054] The hydroxyl value of the terpene phenol resin (A2) used in the disclosed inkjet ink can vary, for example, from 10 mgKOH / g to 150 mgKOH / g. However, from the viewpoints of the decapping behavior and the compatibility with the solvent system (B), the preferred terpene phenol resin (A2) preferably has a hydroxyl value of at least 10 mgKOH / g, preferably at least 15 mgKOH / g, preferably at least 20 mgKOH / g, preferably at least 22 mgKOH / g, preferably at least 24 mgKOH / g, preferably at least 25 mgKOH / g, preferably at least 28 mgKOH / g, preferably at least 30 mgKOH / g, preferably at least 32 mgKOH / g, preferably at least 34 mgKOH / g, more preferably at least 36 mgKOH / g, even more preferably at least 38 mgKOH / g, still even more preferably at least 40 mgKOH / g, and preferably up to 80 mgKOH / g, preferably up to 75 mgKOH / g, preferably up to 70 mgKOH / g, preferably up to 65 mgKOH / g, preferably up to 60 mgKOH / g, more preferably up to 55 mgKOH / g, even more preferably up to 50 mgKOH / g, still even more preferably up to 45 mgKOH / g, and here, a hydroxyl value (OHV) of 20 to 60 mgKOH / g is most preferred.

[0055] Examples of suitable terpene phenol resins (A2) that can be optionally used alone or in combination in the inkjet inks of this specification include YS POLYSTER products such as YS POLYSTER U130 (OHV = 25 mgKOH / g; SP = 130°C), YS POLYSTER U115 (OHV = 30 mgKOH / g; SP = 115°C), YS POLYSTER T160 (OHV = 60 mgKOH / g; SP = 160°C), and YS POLYSTER T145 (OHV = 65 mgKOH / g; SP = 145°C) available from Yasuhara Chemical Co. Ltd., and DERTOPHENE products such as DERTOPHENE T (OHV = 20 - 50 mgKOH / g; SP = 95°C; Mw = 700 g / mol), DERTOPHENE T105 (OHV = 40 mgKOH / g; SP = 105°C; Mw = 700 g / mol), DERTOPHENE T115 (OHV = 50 mgKOH / g; SP = 120°C; Mw = 700 g / mol), and DERTOPHENE T160 (OHV = 60 mgKOH / g; SP = 160°C; Mw = approximately 1000 g / mol) available from DRT / Pinova, but are not limited thereto. A particularly preferred terpene phenol resin (A2) is DERTOPHENE T160.

[0056] In addition to terpene resin (A1) and any optional terpene phenol resin (A2), the inkjet ink may optionally contain other binder resins / tackifiers / adhesive substances in an amount preferably of at least 0.1% by weight, preferably at least 0.5% by weight, preferably at least 1% by weight, more preferably at least 1.5% by weight, even more preferably at least 2% by weight, still even more preferably at least 2.5% by weight, and preferably up to 10% by weight, preferably up to 9% by weight, preferably up to 8% by weight, preferably up to 7% by weight, preferably up to 6% by weight, more preferably up to 5% by weight, even more preferably up to 4% by weight, still even more preferably up to 3% by weight, based on the total weight of the inkjet ink. Such additional resins, binders, tackifiers, or adhesive substances include, but are not limited to, the following. - Rosin resins, including those formed by modifying the aforementioned rosin by esterification, hydrogenation (including partial hydrogenation), dimerization, and / or other modification / functionalization (e.g., by Diels-Alder reaction with unsaturated dibasic acids such as maleic acid or fumaric acid / anhydride, carboxylic acid reduction to respective aldehydes / alcohols, double bond isomerization, dehydrogenation, oxidation, disproportionation, etc.), rosin resins derived from gum rosin, wood rosin, and tall oil rosin (the main components of which are resin acids such as abietic acid, palustric acid, neoabietic acid, pimaric acid, isopimaric acid, and / or dehydroabietic acid).Exemplary rosin resins include (1) rosin esters mainly composed of abietic acid-type or pimaric acid-type resin acids reacted with one or more alcohols such as glycerin, pentaerythritol, ethylene glycol, diethylene glycol, triethylene glycol, methanol, etc., which are optionally hydrogenated or partially hydrogenated. Specific examples include HARIESTER products available from Harima Chemicals, Inc., STAYBELITE ESTER 10-E and PERMALYN 6110 available from Eastman, SUPER ESTER A-125, SUPER ESTER A-75, PENSEL D-125, PINECRYSTAL KE-359 available from Arakawa Chemical Industries, Ltd., and FORAL 85, FORAL 105, HERCOLYN products, PEXALYN products, and PENTALYN products available from Pineau, FORAL AX and FORAL DX available from Pineau, etc. (2) Hydrogenated acidic rosins, STAYBELITE RESIN-E available from Eastman, and STAYBELITE and STAYBELITE A available from Pineau, etc. (3) Partially hydrogenated acidic rosins, POLY-PALE partially dimerized rosin available from Eastman, etc. (4) Dimerized rosins, and (5) functionalized rosin resins, for example, esters of rosin modified with maleic anhydride (e.g., glycerol ester), or rosins subjected to carboxylic acid reduction conditions. Specific examples include LEWISOL 28-M and Abitol-E hydroabietyl alcohol available from Eastman, but are not limited thereto; - Phenolic resins (i.e., copolymers of phenolic compounds and formaldehyde), such as 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 containing sulfonamide-modified epoxy resins, for example, AD-PRO MTS available from Rit-Chem; - (Meth)acrylate and styrene / (meth)acrylate resins, for example, JONCRYL 63, JONCRYL 67, JONCRYL 586, JONCRYL 611, 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.; - Polyols including, but not limited to, polyurethane resins, ethylene glycol, propylene glycol, propane diol, butane diol, polyethylene glycol, polypropylene glycol, polytetrahydrofuran diol, 3-methyl-1,5-pentanediol, 1,9-nonanediol, polyethylene glycol adipate diol, polyethylene glycol succinate diol, poly(3-methyl-1,5-pentanediol adipate) glycol, poly(3-methyl-1,5-pentanediol terephthalate) glycol, etc., and carbonate polyols, (i) polyols, and 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4-diphenylmethane diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate, etc., including but not limited to these, (ii) those formed from the reaction with diisocyanates, such as PERMAX 200, PERMAX 202, and SANCURE 20025F available from Lubrizol; - Polyvinyl butyral resins, such as PIOLOFORM BN 16 and MOWITAL B20H available from Kuraray America, Inc.; - Polyhydroxystyrene resins, such as poly(p-hydroxystyrene) manufactured by DuPont; - 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); - Formaldehyde resins including sulfonamide-modified formaldehyde resins such as p-toluenesulfonamide formaldehyde resin, melamine formaldehyde resin, sulfonamide-modified melamine formaldehyde resin, etc.; - Cellulose ester resins such as cellulose acetate butyrate (CAB-551-0.01) available from Eastman; - and polyesters, sulfonated polyesters, gums, cellulose ethers, nitrocellulose resins, poly(maleic anhydride), acetal polymers, styrene / butadiene copolymers, ketone-aldehyde resins, and polyketone resins; - and equivalents including mixtures thereof.

[0057] In some embodiments, the inkjet ink substantially does not contain additional binder resins / adhesion promoters / adhesive substances such as those described above, other than terpene resin (A1) and any optional terpene phenol resin (A2). In some embodiments, the inkjet ink contains a combination of terpene resin (A1) and terpene phenol resin (A2), and preferably substantially does not contain additional resins, binders, adhesion promoters, or adhesive substances. In some embodiments, terpene resin (A1) is the only resin present in the disclosed inkjet ink. In some embodiments, the inkjet ink substantially does not contain rosin resins. In some embodiments, the inkjet ink substantially does not contain rosin ester resins, partially hydrogenated acidic rosin, dimerized rosin, and other functionalized / modified rosin resins.

[0058] (B) Solvent system In many printing processes that utilize solvent-based inks, particularly in thermal inkjet printing, the selection of an appropriate solvent system can affect 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 selection of the solvent system can: 1) assist in bubble formation during the jetting process to result in reliable ink jetting; 2) affect the stability / volatility of the inkjet ink by changing the interaction dynamics between the solvent(s) and various inkjet ink components, and thus affect decap behavior, cogenation, operating stability, and / or droplet trajectory; 3) affect the adhesion, friction, and scratch resistance of the printed image, as well as the optical density characteristics, by the interaction forces between the solvent system and other inkjet ink components, whether the solvent(s) no longer exist after drying or exist in a lesser amount; 4) affect the drying time after application or the apparatus required to dry the applied ink; and / or 5) affect droplet dynamics.

[0059] In light of the above, particularly preferred herein is an inkjet ink comprising a solvent system (B) containing dioxolane (B1). Dioxolane (1,3-dioxolane) is a heterocyclic acetal having the chemical formula (CH2)2O2CH2. Surprisingly, it has been found that by including dioxolane (B1), various properties of the ink are improved. Such an ink formulated with dioxolane (B1) exhibits excellent decap behavior even with a decap time of up to 60 minutes, excellent printing life or operating stability (e.g., over 5000 pages), and excellent adhesion on a number of substrates. On the other hand, the inkjet inks described herein that do not contain dioxolane are unable to provide a readable image with the shortest decap time tested (30 seconds) and have insufficient operating stability (less than 1000 pages).

[0060] Dioxolane has also been found to be a unique solvent with respect to the solubility / compatibility not only with the resin(s) (A) in the disclosed inkjet ink but also with the colorant (C).

[0061] The amount of dioxolane (B1) suitable for achieving the desired ink properties (e.g., decapping behavior, driving stability, adhesiveness, etc.) is preferably at least 2% by weight, preferably at least 4% by weight, preferably at least 5% by weight, preferably at least 10% by weight, preferably at least 15% by weight, preferably at least 20% by weight, preferably at least 25% by weight, preferably at least 30% by weight, preferably at least 35% by weight, more preferably at least 40% by weight, more preferably at least 45% by weight, more preferably at least 50% by weight, even more preferably at least 55% by weight, still more preferably at least 60% by weight, up to preferably 98% by weight, preferably up to 97.5% by weight, preferably up to 97% by weight, preferably up to 96.5% by weight, preferably up to 96% by weight, preferably up to 95.5% by weight, preferably up to 95% by weight, more preferably up to 94.5% by weight, more preferably up to 94% by weight, more preferably up to 93.5% by weight, more preferably up to 93% by weight, even more preferably up to 92.5% by weight, even more preferably up to 92% by weight, even more preferably up to 91.5% by weight, still more preferably up to 91% by weight, based on the total weight of the inkjet ink, and can be in the range.

[0062] The solvent system (B) may also optionally contain (B2) an alcohol solvent. Inclusion of the alcohol solvent (B2) can be beneficial for promoting solvation of the inkjet ink components, and in particular for promoting injectability, among other advantages, especially when the terpene phenol resin (A2) is used.

[0063] The alcohol solvent (B2) contains at least 1 carbon atom, preferably at least 2 carbon atoms, more preferably at least 3 carbon atoms, and may contain up to 8 carbon atoms, preferably up to 6 carbon atoms, more preferably up to 4 carbon atoms. The preferred alcohol solvent (B2) preferably has a boiling point of less than 120°C, preferably less than 115°C, preferably less than 110°C, more preferably less than 105°C, even more preferably less than 100°C, and still even more preferably less than 98°C.

[0064] Suitable examples of alcohol solvents that can be used alone or in combination in the disclosed inkjet ink include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-pentanol, 3-pentanol, and t-amyl alcohol, and particularly 1-propanol, but are not limited thereto.

[0065] When used, the alcohol solvent (B2) is preferably at least 0.5% by weight, preferably at least 0.75% by weight, preferably at least 1% by weight, preferably at least 1.25% by weight, preferably at least 1.5% by weight, preferably at least 1.75% by weight, preferably at least 2% by weight, preferably at least 2.25% by weight, preferably at least 2.5% by weight, preferably at least 2.75% by weight, preferably at least 3% by weight, preferably at least 3.25% by weight, preferably at least 3.5% by weight, preferably at least 3.75% by weight, preferably at least 4% by weight, preferably at least 4.25% by weight, preferably at least 4.5% by weight, preferably at least 4.75% by weight, preferably at least 5% by weight, and preferably up to 60% by weight, preferably up to 55% by weight, preferably up to 50% by weight, preferably up to 45% by weight, preferably up to 40% by weight, more preferably up to 37.5% by weight, more preferably up to 35% by weight, even more preferably up to 34.5% by weight, even more preferably up to 34% by weight, even more preferably up to 33.5% by weight, even more preferably up to 33% by weight, even more preferably up to 32.5% by weight, even more preferably up to 32% by weight, even more preferably up to 31.5% by weight, even more preferably up to 31% by weight, still even more preferably up to 30.75% by weight, still even more preferably up to 30.5% by weight, still even more preferably up to 30.25% by weight, still even more preferably up to 30% by weight, based on the total weight of the inkjet ink, and can be present in an amount of

[0066] In a preferred embodiment, dioxolane (B1) together with an alcohol solvent (B2) constitutes most of the solvent system (B) used in the inkjet ink, that is, the combined weight of dioxolane (B1) and the alcohol solvent (B2) is preferably at least 50% by weight, preferably at least 60% by weight, more preferably at least 70% by weight, preferably at least 80% by weight, preferably at least 90% by weight, preferably at least 95% by weight, preferably at least 96% by weight, preferably at least 98% by weight, more preferably at least 99% by weight, even more preferably at least 99.5% by weight, and still more preferably in the range of 100% by weight, based on the total weight of the solvent system (B).

[0067] For dioxolane (B1), a preferred inkjet ink preferably has a weight ratio of dioxolane (B1) to alcohol solvent (B2) ((B1):(B2)) of from preferably 0.25:1, preferably from 0.5:1, preferably from 0.75:1, preferably from 1:1, preferably from 1.25:1, more preferably from 1.5:1, even more preferably from 1.75:1, and still more preferably from 2:1, and preferably up to 30:1, preferably up to 25:1, preferably up to 20:1, preferably up to 17.5:1, preferably up to 15:1, preferably up to 12.5:1, preferably up to 10:1, preferably up to 7.5:1, preferably up to 5:1, more preferably up to 4.5:1, even more preferably up to 4:1, and still more preferably up to 3.5:1.

[0068] For the terpene resin (A1), a preferred inkjet ink preferably has a weight ratio ((B1):(A1)) of dioxolane (B1) to terpene resin (A1) in the range of preferably at least 20:1, preferably at least 25:1, preferably at least 30:1, preferably at least 35:1, preferably at least 40:1, preferably at least 45:1, preferably at least 50:1, preferably at least 55:1, preferably at least 60:1, preferably at least 65:1, preferably at least 70:1, preferably at least 75:1, more preferably at least 80:1, even more preferably at least 85:1, still even more preferably at least 90:1, and preferably up to 250:1, preferably up to 225:1, preferably up to 200:1, preferably up to 175:1, preferably up to 150:1, more preferably up to 125:1, more preferably up to 120:1, more preferably up to 115:1, more preferably up to 110:1, even more preferably up to 105:1, still even more preferably up to 100:1.

[0069] The amount of the alcohol solvent (B2) can be adjusted to provide, for example, a desired solvation level. Preferred inkjet inks preferably have a weight ratio ((A1):(B2)) of terpene resin (A1) to alcohol solvent (B2) that is preferably at least from 1:75, preferably at least from 1:70, preferably at least from 1:65, preferably at least from 1:60, preferably at least from 1:55, preferably at least from 1:50, preferably at least from 1:45, preferably at least from 1:40, preferably at least from 1:35, preferably at least from 1:30, more preferably at least from 1:27.5, more preferably at least from 1:25, more preferably at least from 1:22.5, even more preferably at least from 1:20, still even more preferably at least from 1:19, and is preferably up to 1:2, preferably up to 1:5, preferably up to 1:7.5, preferably up to 1:10, more preferably up to 1:12.5, more preferably up to 1:15, more preferably up to 1:17.5, more preferably up to 1:18.5.

[0070] In addition to the solvents described above, the solvent system may optionally include one or more other organic solvents.

[0071] Examples of other organic solvents include, but are not limited to, the following. - Alcohols excluding the alcohol solvent (B2), such as terpene alcohols including monoterpene alcohols (e.g., terpineol, geraniol, citronellol, linalool, etc.), 2-methyl-1-butanol, undecanol (e.g., 1-undecanol), dodecanol (e.g., 1-dodecanol), tridecanol (e.g., 1-tridecanol), tetradecanol (e.g., 1-tetradecanol); - Polyols such as trimethylene glycol, 1,2-hexanediol, and glycerol; - Glycol ethers including monoalkyl glycol ethers, dialkyl glycol ethers, and monoalkyl monoester glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol mono-n-propyl ether, ethylene glycol mono-t-butyl ether, ethylene glycol monobutyl ether, ethylene glycol monoisobutyl 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 monoisopropyl ether, propylene glycol mono-n-butyl ether, dipropylene glycol monomethyl ether, propylene glycol methyl 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; - Ethers (non-glycol ethers) such as diethyl ether, dipropyl ether, methyl tert-butyl ether, and tetrahydrofuran, dibutyl ether, and dioxane; - Ketone solvents such as acetone, methyl ethyl ketone (MEK), methyl isopropyl ketone, 3-pentanone, methyl n-propyl ketone, ethyl isopropyl ketone, methyl isobutyl ketone, cyclohexanone, diacetone alcohol, 3-hexanone, and methyl n-butyl ketone; - Esters such as methyl acetate, ethyl acetate, n-butyl acetate, methyl lactate, ethyl lactate, butyl lactate, methoxyethyl acetate, ethoxyethyl acetate, methoxypropyl acetate, and ethoxypropyl acetate; - Amides such as dimethylformamide and dimethylacetamide; - Acetonitrile; - and mixtures of two or more of them.

[0072] Other organic solvent(s) can be used in any amount desirable for a particular application, where typical loadings are preferably up to 20 wt%, preferably up to 15 wt%, preferably up to 10 wt%, preferably up to 5 wt%, more preferably up to 4 wt%, even more preferably up to 2 wt%, still even more preferably up to 1 wt% based on the total weight of the inkjet ink, although occasionally higher loadings may be used. In some embodiments, the inkjet ink is substantially free of other organic solvents.

[0073] In some embodiments, the inkjet ink is substantially free of solvents having a boiling point higher than preferably 255 °C, preferably higher than 250 °C, preferably higher than 245 °C, preferably higher than 240 °C, preferably higher than 235 °C, preferably higher than 230 °C, preferably higher than 220 °C, preferably higher than 210 °C, more preferably higher than 200 °C, even more preferably higher than 195 °C. In some embodiments, the inkjet ink is substantially free of ketone solvents having a boiling point of 120 °C or higher, examples of which include, but are not limited to, 3 - hexanone, methyl n - butyl ketone, and cyclohexanone.

[0074] In some embodiments, the inkjet ink preferably substantially does not contain a ketone solvent having a boiling point of less than 120°C, preferably less than 115°C, preferably less than 110°C, preferably less than 105°C, preferably less than 100°C, preferably less than 95°C, more preferably less than 90°C, even more preferably less than 85°C, and still even more preferably less than 80°C. Such ketone solvents can contain 3, 4, 5, or 6 carbon atoms. Examples of such ketone solvents include, but are not limited to, acetone, methyl ethyl ketone (MEK), 3-pentanone, methyl n-propyl ketone, methyl isopropyl ketone, ethyl isopropyl ketone, and methyl isobutyl ketone. In some embodiments, the inkjet ink substantially does not contain methyl ethyl ketone. In some embodiments, the inkjet ink does not contain methyl ethyl ketone.

[0075] The solvent system (B) may also optionally contain a glycol ether in order to further improve the decap performance without substantially worsening the drying time of the ink. The glycol ether may be a monoalkyl ether, a dialkyl ether, a monoalkyl monoester ether, or a combination thereof, and preferably, the glycol ether is a monoalkyl monoester ether, that is, a glycol compound in which one hydroxyl group is etherified and the other hydroxyl group is esterified. The glycol ether preferably contains at least 3 carbon atoms, preferably at least 4 carbon atoms, more preferably at least 5 carbon atoms, even more preferably at least 6 carbon atoms, and can preferably contain up to 12 carbon atoms, preferably up to 10 carbon atoms, more preferably up to 8 carbon atoms.

[0076] In some embodiments, the solvent system (B) may contain a mixture of glycol ethers, for example, preferably at least 1:5, preferably at least 1:4, more preferably at least 1:3, even more preferably at least 1:2, still even more preferably at least 1:1, and preferably up to 5:1, preferably up to 4:1, more preferably up to 3:1, even more preferably up to 2:1 by weight of a first glycol ether and a second glycol ether.

[0077] Acceptable examples of glycol ethers that may optionally be included in the disclosed inkjet ink include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monopropyl ether, ethylene glycol monot-butyl ether, ethylene glycol monobutyl ether, ethylene glycol monoisobutyl ether, diethylene glycol monomethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monot-butyl ether, propylene glycol monopropyl ether, propylene glycol monoisopropyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, ethylene glycol monobutyl ether acetate, propylene glycol methyl ether acetate, diethylene glycol monobutyl 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 monopropyl ether, and mixtures thereof, but are not limited thereto.

[0078] From the perspective of improving the decapping performance of inkjet inks without significantly extending the drying time of the inks, preferred glycol ethers preferably have a boiling point of less than 214°C, preferably less than 210°C, more preferably less than 205°C, even more preferably less than 200°C, and still even more preferably less than 195°C.

[0079] In light of the above, ethylene glycol monobutyl ether acetate, ethylene glycol monomethyl ether, propylene glycol monomethyl ether, ethylene glycol monopropyl ether, and propylene glycol monopropyl ether are preferred, and specifically, ethylene glycol monobutyl ether acetate is mentioned.

[0080] When used, the glycol ether may be present in the inkjet ink, preferably in an amount of at least 0.1% by weight, preferably at least 0.3% by weight, preferably at least 0.5% by weight, preferably at least 0.7% by weight, more preferably at least 1% by weight, even more preferably at least 1.5% by weight, and still even more preferably at least 2% by weight, based on the total weight of the inkjet ink, and preferably up to 20% by weight, preferably up to 15% by weight, more preferably up to 10% by weight, even more preferably up to 5% by weight, and still even more preferably up to 3% by weight. In some embodiments, the inkjet ink is substantially free of glycol ether.

[0081] In some embodiments, the inkjet ink is substantially free of alcohol solvent (B2). In a preferred embodiment, the solvent system (B) consists of dioxolane (B1) and alcohol solvent (B2).

[0082] In a preferred embodiment, the inkjet ink of the present disclosure is substantially non-aqueous, which means that no water is added to the inkjet ink other than an incidental amount of moisture that may be derived from ambient conditions. In such a case, the inkjet ink may preferably have less than 1% by weight, preferably less than 0.5% by weight, preferably less than 0.1% by weight, more preferably less than 0.05% by weight, even more preferably less than 0.01% by weight, and still even more preferably 0% by weight of water, based on the total weight of the inkjet ink.

[0083] (C) Colorant The inkjet ink of the present disclosure contains a colorant that includes a metal complex azo dye. In this context, the term "metal complex azo dye" refers to a dye that includes a compound formed from a metal center and a ligand containing an azo functional group (also known as a diazenyl functional group). Typically, the ligand containing the azo functional group is a molecule that can itself be regarded as an azo dye.

[0084] This ligand containing the azo functional group is typically coordinated to a metal center that is a transition metal or a main group metal or a metalloid, but not to an alkali metal or an alkaline earth metal.

[0085] Examples of suitable metals that can form a 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 via any suitable functional group present on the ligand. Examples of such functional groups include oxygen-containing functional groups such as alcohols, alkoxides, carboxylic acids and carboxylates, esters, ketones, and ethers; nitrogen-containing functional groups such as amines, amides, azides, diazenyl (azo group), imines, porphyrins, imides, isonitriles, nitriles, and nitro functional groups; phosphorus-containing functional groups such as phosphines, phosphites, phosphates, phosphonites, phosphonates, phosphinites, and phosphinates; and sulfur-containing functional groups such as thiols, thiolates, disulfides, sulfones, sulfonic acids and sulfonates, sulfoxides, thioethers, thioesters, thiosulfinates, thiocarboxylic acids and thiocarboxylates, sulfinic acids and sulfonates, thiocyanates, and isothiocyanates; but are not limited to these. The ligand coordinated to the metal center can be monodentate or bidentate, tridentate, or tetradentate. Typically, a ligand containing an azo group as used herein forms a coordination interaction with the metal center via one or both of the nitrogen atoms forming the azo group.

[0086] Generally, the remainder of the inner coordination sphere of the metal center can be further filled by any suitable ligand or combination of ligands known to those skilled in the art. Examples of suitable ligands include species having oxygen-containing functional groups such as alcohols, alkoxides, hydroxides, carboxylic acids and carboxylates, esters, and ethers; species having nitrogen-containing functional groups such as amines (understood herein to include ammonia), amides, azides, other diimides (also known as azo compounds), imines, porphyrins, imides, isonitriles, nitriles, and nitro compounds; species having phosphorus-containing functional groups such as phosphines, phosphites, phosphates, phosphonites, phosphonates, phosphinites, and phosphinates; species having sulfur-containing functional groups such as thiols, thiolates, disulfides, sulfones, sulfonic acids and sulfonates, sulfoxides, thioethers, thioesters, thiosulfinates, thiocarboxylic acids and thiocarboxylates, sulfinic acids and sulfinates, thiocyanates, and isothiocyanates; hydrocarbons containing one or more π-electron systems such as mesitylene, cyclopentadienyl anion, and cyclooctadecene; halides; and water. Generally, the ligand can be monodentate, bidentate, tridentate, tetradentate, or pentadentate as appropriate. However, hexadentate ligands such as ethylenediaminetetraacetic acid (EDTA) are not suitable because such ligands do not leave open coordination sites for a suitable ligand containing an azo functional group to coordinate. Generally, the functional group can occupy any suitable position on the molecule that functions as a ligand. For example, an alcohol or an amine can be a primary alcohol or primary amine, a secondary alcohol or secondary amine, or a tertiary alcohol or tertiary amine as appropriate.

[0087] In a preferred embodiment, the metal complex azo dye is a metal complex comprising a metal center and (E)-1-((2-methoxy-5-nitrophenyl)diazenyl)naphthalen-2-ol or its deprotonated form, demethylated form, deprotonated and demethylated form, tautomer, or stereoisomer. The structure of (E)-1-((2-methoxy-5-nitrophenyl)diazenyl)naphthalen-2-ol is shown in Formula 1 below: [Chemical Formula]

[0088] To form a suitable metal complex, (E)-1-((2-methoxy-5-nitrophenyl)diazenyl)naphthalen-2-ol may exist in its deprotonated form in which the hydroxyl group is deprotonated to form an alkoxide-type ligand (see Formula (2) below), its demethylated form in which the methoxy group is converted to an alkoxide-type ligand (see Formula (3) below), or its deprotonated and demethylated form in which the hydroxyl group is deprotonated to form an alkoxide-type ligand and the methoxy group is converted to an alkoxide-type ligand (see Formula (4) below).

[0089] [Chemical Formula] [Chemical Formula] [Chemical Formula]

[0090] In a preferred embodiment, the metal center is a chromium ion. In some embodiments, the chromium ion is in a +3 oxidation state. In such embodiments, the metal complex may have a positive charge, a negative charge, or no charge. In embodiments where the metal complex has a positive charge, the metal complex azo dye may further include any anion suitable 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 where the metal complex has a negative charge, the metal complex azo dye may further include any cation suitable for charge balance. Examples of such suitable cations include, but are not limited to, alkali metals, alkaline earth metals, ammonium compounds, and mixtures thereof.

[0091] Preferably, an electric dipole is generated by the coordination between the metal and the ligand containing an azo functional group. The presence of such an electric dipole can be advantageous for causing a strong interaction between the metal complex azo dye and a polar solvent such as dioxolane (B1). Furthermore, the metal complex azo dye preferably includes a hydrophobic portion, for example, another functional group. The presence of such a hydrophobic portion can be advantageous for providing sufficient interaction between the metal complex azo dye and the terpene resin (A1). Using such a metal azo complex as a mediator can be particularly advantageous for the inkjet ink of the present application because the combination of the terpene resin (A1) and dioxolane (B) is one of the main factors that result in the rapid formation of a "film" or "coating" of the present invention.

[0092] Examples of suitable metal complex azo dyes include 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 Yellow 19, Solvent Yellow 21, Solvent Yellow 25, Solvent Yellow 82, Solvent Yellow 88, Solvent Yellow 146, Solvent Violet 58, Solvent Violet 61, and VALIFAST BLACK 3870, VALIFAST RED 1355, and VALIFAST YELLOW 3150, respectively available from Orient Chemical Industries Co., Ltd., but are not limited thereto. In particular, Solvent Black 27 (also sold as VALIFAST BLACK 3830 available from Orient Chemical Industries Co., Ltd.) is mentioned.

[0093] The amount of the colorant (C) suitable for achieving the desired ink properties (e.g., decapping behavior, driving stability, adhesiveness, etc.) can preferably be from at least 0.5% by weight, preferably from at least 1% by weight, preferably from at least 3% by weight, preferably from at least 5% by weight, preferably from at least 7% by weight, and can preferably be in the range up to 20% by weight, preferably up to 15% by weight, preferably up to 12% by weight, preferably up to 10% by weight, preferably up to 9% by weight, based on the total weight of the inkjet ink.

[0094] The amount of the metal azo dye suitable for achieving the desired ink properties (e.g., decapping behavior, driving stability, adhesiveness, etc.) can preferably be from at least 0.5% by weight, preferably from at least 1% by weight, preferably from at least 3% by weight, preferably from at least 5% by weight, preferably from at least 7% by weight, based on the total weight of the inkjet ink, and can preferably range up to 20% by weight, preferably up to 15% by weight, preferably up to 12% by weight, preferably up to 10% by weight, preferably up to 9% by weight.

[0095] By including a colorant (C) containing a dye or pigment other than the metal complex azo dye as the colorant (C2) in the inkjet ink, any desired color can be imparted. The colorant (C2) can be provided such that this colorant can be dissolved or stably dispersed in the inkjet ink. Suitable colors include, for example, cyan, magenta, yellow, and key (black) ("CMYK"), white, orange, green, light cyan, light magenta, violet, etc. (including both spot colors and process colors).

[0096] Generally, when the additional colorant (C2) is used, it can preferably be in an amount of at least 0.1% by weight, preferably at least 0.5% by weight, preferably at least 1% by weight, preferably at least 2% by weight, preferably at least 3% by weight, based on the total weight of the inkjet ink, and can be used in an amount preferably up to 10% by weight, preferably up to 8% by weight, preferably up to 7% by weight, preferably up to 6% by weight, preferably up to 5% by weight.

[0097] The weight of the metal azo dye suitable for achieving the desired ink properties (e.g., decapping behavior, driving stability, adhesiveness, etc.) can preferably range from at least 50% by weight, preferably from at least 75% by weight, preferably from at least 95% by weight, preferably from at least 98% by weight, preferably from at least 99% by weight, preferably 100% by weight, based on the total weight of the colorant (C).

[0098] The inkjet ink can be blended with various inorganic pigments and / or organic pigments. In addition to imparting color to the inkjet ink, such pigments may be able to improve the lightfastness, weather resistance, etc. of the printed image.

[0099] (D) Surfactant The inkjet ink of the present disclosure optionally contains (D) a surfactant, and can provide, among other advantages, anti-sticking properties, ink acceptance properties, leveling properties, crater prevention properties, increased surface slip properties, and / or wetting properties of the substrate, for example, without sacrificing the decapping performance of the inkjet ink. When used, the amount of the surfactant (D) used is preferably at least 0.01% by weight, preferably at least 0.015% by weight, preferably at least 0.02% by weight, preferably at least 0.04% by weight, more preferably at least 0.06% by weight, still more preferably at least 0.08% by weight, still more preferably at least 0.1% by weight, still more preferably at least 0.15% by weight, still more preferably at least 0.2% by weight, still more preferably at least 0.25% by weight, still more preferably at least 0.3% by weight, still more preferably at least 0.35% by weight, still more preferably at least 0.4% by weight, still more preferably at least 0.45% by weight, still more preferably at least 0.5% by weight, based on the total weight of the inkjet ink, and can be in the range of preferably up to 5% by weight, preferably up to 4% by weight, preferably up to 3% by weight, preferably up to 2% by weight, preferably up to 1% by weight, preferably up to 0.95% by weight, preferably up to 0.9% by weight, still more preferably up to 0.85% by weight, still more preferably up to 0.8% by weight.

[0100] Examples of the surfactant (D) that can be used alone or in combination in the present specification include, but are not limited to, the following. - Polysiloxanes containing organically modified silicones (e.g., alkyl, aryl, and / or arylalkyl modified silicones), such as SILTECH C-32 available from Siltech Corporation, COATOSIL 1211C and 3573 available from Momentive respectively, KF-410 (arylalkyl modified polydimethylsiloxane) available from Shin-Etsu Chemical Co., and BYK-322 and BYK-323 (arylalkyl modified poly(dimethylsiloxane-co-methylalkylsiloxane)) available from BYK Additives & Instruments respectively; - Silicone acrylate copolymers, such as KP-541, KP-543, KP-545, KP-550, and KP-575 (acrylic polymers grafted on the polydimethylsiloxane side chain, available from Shin-Etsu Chemical Co.), and BYK-3550 (available from BYK Japan K.K.); - Polyether modified silicones, including those which are 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; - Fluoropolymers, such as FC-4430 and FC-4432 available from 3M Corporation; - Polyether-modified silicones, including 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, for example, KF-6013 (PEG-9 dimethicone, unblocked, HLB = 10.0), KF-6015 (PEG-3 dimethicone, unblocked, HLB = 4.5), KF-6017 (PEG-10 dimethicone, unblocked, HLB = 4.5), and KF-6038 (lauryl PEG-9 polydimethylsiloxyethyl dimethicone, unblocked, HLB = 3.0), each available from Shin-Etsu Chemical Co., Ltd., and BYK-307 (polyether-modified polydimethylsiloxane) available from BYK Additives & Instruments; - Photocrosslinkable silicone acrylates or silicone polyether acrylates such as TEGO RAD 2100, TEGO RAD 2200, TEGO RAD 2250, TEGO RAD 2300 (silicone polyether 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-381 and BYK-361N (polyacrylate copolymers), each available from BYK, and PEMULEN EZ-4U (acrylate / C10 - C30 alkyl acrylate crosspolymer) and PEMULEN TR-2 (acrylic acid / C10 - C30 alkyl acrylate crosspolymer), each available from Lubrizol; - Gemini-type surfactants based on acetylene diols and acetylene glycols such as SURFYNOL SEF and DYNOL surfactants available from Evonik Industries; - Gemini-type surfactants based on polysiloxanes such as TEGO TWIN 4100 available from Evonik Industries; - Nonionic polyethers such as TEGO WET 510 (hydrophilic polyether-based wetting surfactant) available from Evonik Industries, for example, as a substrate wetting surfactant; - Amides or monoalkanolamides of fatty acids containing alkoxylated monoalkanolamides of fatty acids such as coconut fatty acid monoethanolamide and coconut fatty acid monoethanolamide reacted with 2 - 20 mol of ethylene oxide; - Alkoxylated C1 - C22 alcohols containing 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 tridecyl alcohol) available from Stepan respectively, ethylene oxide / propylene oxide copolymers, alkoxylated alkylphenols, and ethers such as alkyl polyglycosides (APG) produced from the reaction of fatty alcohols and glucose; - Alkoxylated and / or propoxylated fatty acids (for example, castor oil containing 2 - 40 mol of ethylene oxide), alkoxylated glycerides (for example, PEG-24 glyceryl monostearate), glycol esters and derivatives, monoglycerides, polyglyceryl esters, esters of polyalcohols, and sorbitan / sorbitol esters such as sorbitan monolaurate (for example, EMASOL L-10V available from Kao Corporation), and polysorbates containing monovalent, divalent, or trivalent fatty acid esterified polysorbates such as TOXIMUL SEE-340 (sorbitan trioleate ethoxylate (20)) available from Stepan; - Glycosides of fatty alcohols such as PLANTASENS NATURAL EMULSIFIER HE20 (cetearyl glucoside, sorbitan olivate) available from Clariant; - Sulfates, sulfonates, phosphates, and phosphonates, such as alkyl sulfates, alkyl ester sulfates, alkyl ether sulfates, alkyl alkoxy ester sulfates, sulfated alkanolamides, glyceride sulfates, alkyl sulfonates, fatty alkylbenzene sulfonates, lower alkylbenzene sulfonates, alpha olefin sulfonates, lignosulfonates, alkyl aryl ether phosphates, alkyl ether phosphates, and phosphates of fatty alcohols or polyoxyalkylene ethers of fatty alcohols; and, - Amphoteric surfactants including, but not limited to, fatty alkyl betaines such as lauryl betaine (e.g., AMPHITOL 24B available from Kao Corporation); fatty alkyl amide betaines such as fatty amide propyl dimethylamino betaine; fatty alkyl sultaines such as fatty dimethyl hydroxy sultaine; fatty alkyl amide sultaines such as fatty amide propyl dimethylamino hydroxy sultaine; dimethyl fatty alkyl amine oxides such as N-cocamide propyl dimethylamine oxide, dimethyl cocamine oxide, and amine oxides such as lauryl dimethylamine oxide (e.g., AMPHITOL 20N available from Kao Corporation); and imidazole-based amphoteric surfactants (e.g., ELEC AC available from Kao Corporation).

[0101] When a surfactant (D) is incorporated into the inkjet ink, a particularly preferred surfactant is a silicone acrylate copolymer. The silicone acrylate copolymer can be obtained by polymerization (e.g., free radical polymerization) or grafting of a polyorganosiloxane macromer containing at least one polymerizable group (e.g., at one end of the polyorganosiloxane chain, at both ends of the polyorganosiloxane chain, or on the silicone backbone) and a (meth)acrylate monomer, which is described, for example, in U.S. Patent No. 5,219,560, the entire disclosure of which is incorporated herein by reference. Preferably, the silicone acrylate copolymer is a polysiloxane (polyorganosiloxane) - modified poly(meth)acrylate, i.e., a copolymer (i.e., a graft copolymer) composed of a poly(meth)acrylate backbone and one or more polyorganosiloxane side chains grafted to the poly(meth)acrylate backbone. In a preferred embodiment, the majority of the silicone acrylate copolymer is poly(meth)acrylate. In a preferred embodiment, the silicone acrylate copolymer has a polyorganosiloxane content of preferably at least 1 wt%, preferably at least 2 wt%, more preferably at least 3 wt%, even more preferably at least 4 wt% based on the total weight of the silicone acrylate copolymer, and preferably up to 20 wt%, preferably up to 15 wt%, more preferably up to 10 wt%, even more preferably up to 8 wt%.

[0102] The polyorganosiloxane macromer can be formed from the polymerization and / or polycondensation of appropriately functionalized silanes and has a polysiloxane backbone structure (-Si-O-Si- in which silicon atoms are linked through oxygen atoms), and can be based on any organosilicon polymer or oligomer of linear structure of various molecular weights in which an alkyl group, an aryl group, and / or an arylalkyl group is directly bonded to a (tetravalent) silicon atom. For example, the polyorganosiloxane backbone can be a polydimethylsiloxane backbone (each silicon atom in this backbone is directly bonded to two methyl groups), a poly(dimethylsiloxane-co-methylphenylsiloxane) backbone, a poly(dimethylsiloxane-co-diphenylsiloxane) backbone, or a poly(dimethylsiloxane-co-methylalkylsiloxane) backbone.

[0103] The polyorganosiloxane macromer may be modified to contain at least one polymerizable group (e.g., a (meth)acrylate-containing group). Preferably, the polyorganosiloxane macromer may be end-group modified to contain a polymerizable group at at least one end of the polysiloxane chain. In some embodiments, the polyorganosiloxane macromer has polymerizable groups at both ends of the polysiloxane chain. In some embodiments, the polyorganosiloxane macromer has a polymerizable group at one end of the polysiloxane chain and non-polymerizable end groups (e.g., trimethylsilane, triphenylsilane, phenyldimethylsilane, etc.) at the other end of this chain. In some embodiments, the polymerizable group may be a styrenyl-type group (CH2 = C(R1)-arylene-) or a (meth)acrylate group, particularly a group represented by CH2 = CR1-CO-O-R2-, where R1 is hydrogen or a methyl group, and R2 preferably has 1 to 10 carbon atoms, preferably 2 to 8 carbon atoms, preferably 3 to 6 carbon atoms, and optionally contains an ether bond (e.g., 1, 2, 3, 4, etc. ether bonds), and optionally contains a substituent(s) of a hydroxyl group (e.g., in the case of a ring-opening product resulting from the reaction between an epoxide and (meth)acrylic acid), and is a divalent linear or branched hydrocarbon group. In a preferred embodiment, R2 is -(CH2)n- (n = 1 to 10), -CH2CH(CH3)CH2-, -CH2CH2OCH2CH2-, -CH2CH2OCH2CH2CH(CH3)CH2-, -CH2CH2OCH2CH2OCH2CH2CH2-, and -CH2CH(OH)CH2OCH2CH2CH2-.

[0104] A silicone acrylate copolymer can be produced by polymerizing a polyorganosiloxane macromer in the presence of various (meth)acrylate monomers such as the aforementioned (meth)acrylate monomers including both (meth)acrylic acid (acrylic acid and methacrylic acid) and another form of esters which can be aryl or alkyl (meth)acrylate esters. The poly(meth)acrylate backbone may be formed from one type of monomer or alternatively from two or more types of (meth)acrylate monomers. In a preferred embodiment, the (meth)acrylate monomer is a (meth)acrylate alkyl ester which can be selected from linear, branched, or cyclic alkyl esters, for example, C1-C22 alkyl esters of acrylate and methacrylate, preferably C2-C20 alkyl esters, preferably C3-C18 alkyl esters. In some embodiments, the alkyl group is selected from methyl, ethyl, butyl, stearyl, isostearyl, and 2-ethylhexyl, and mixtures thereof. Suitable (meth)acrylate monomers include, but are not limited to, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, tert-butyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, tridecyl acrylate, stearyl acrylate, isostearyl acrylate, behenyl acrylate, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, tert-butyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, tridecyl methacrylate, stearyl methacrylate, isostearyl methacrylate, behenyl methacrylate, and combinations thereof.

[0105] In some embodiments, the silicone acrylate copolymer preferably has a weight average molecular weight starting from 3,000 g / mol, preferably from 4,000 g / mol, more preferably from 5,000 g / mol, even more preferably from 8,000 g / mol, still even more preferably from 10,000 g / mol, and preferably up to 500,000 g / mol, preferably up to 400,000 g / mol, more preferably up to 300,000 g / mol, even more preferably up to 200,000 g / mol, still even more preferably up to 100,000 g / mol.

[0106] When used in an inkjet ink, the silicone acrylate copolymer may be used as is or alternatively may be dispersed or dissolved in an organic solvent such as a lower alcohol containing 2 to 8 carbon atoms (e.g., ethanol, 1-propanol, 2-propanol, 1-butanol, etc.), an ester solvent (e.g., methoxyethyl acetate, ethoxyethyl acetate, methoxypropyl acetate, ethoxypropyl acetate, butyl acetate, etc.), or an oil (e.g., cyclopentasiloxane). In some embodiments, when used as a dispersion or solution, the solvent is an ester solvent, most preferably methoxypropyl acetate. In some embodiments, the content of the solid (silicone acrylate copolymer) in the dispersion or solution is preferably at least 30% by weight, preferably at least 40% by weight, preferably at least 50% by weight, based on the total weight of the dispersion / solution, and preferably up to 60% by weight, preferably up to 55% by weight, preferably up to 52% by weight.

[0107] Representative examples of commercially available silicone acrylate copolymers that can be used in the inkjet inks described herein include KP-541, KP-543, KP-545, KP-550, KP-575 (an acrylic polymer grafted with polydimethylsiloxane side chains, available from Shin-Etsu Chemical Co., Ltd.), BYK-3550 (available from BYK-Chemie Japan Co., Ltd.), and mixtures thereof, but are not limited thereto. In a preferred embodiment, the silicone acrylate copolymer is BYK-3550.

[0108] In some embodiments, the inkjet inks of the present disclosure are substantially free of surfactants such as those listed above.

[0109] (E) Additive(s) In addition to the components already described, various additives (E) can optionally be incorporated into the inkjet ink to improve various ink properties and performance. For example, the inkjet ink can optionally contain, at appropriate levels in the art, one or more of an anti-cogulation agent, a stabilizer, a wetting agent, a security taggant, or other inkjet additives known to those skilled in the art.

[0110] The inkjet ink can optionally contain one or more opacifying agents, examples of which include 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, but are not limited thereto.

[0111] Manufacturing Method Embodiments of the inkjet ink described herein can be prepared by any suitable technique known to those skilled in the art, for example, by combining (A1) terpene resin and (C) colorant and any desired optional components (e.g., (A2) terpene phenol resin, surfactant (D), and / or additive (E)) with a suitable solvent system (B) comprising (B1) dioxolane and optionally (B2) alcohol solvent in any order, and stirring, agitating, and / or homogenizing for an appropriate amount of time at a temperature between 20°C and 100°C to form a homogeneous solution.

[0112] In one example, the inkjet ink can be produced by first combining the terpene resin (A1) with dioxolane (B1) and any optional resin (e.g., terpene phenol resin (A2)), optional alcohol solvent (B2), optional surfactant (D), or other optional additive(s) (E) in a container and then stirring, preferably for at least 10 minutes, preferably for at least 15 minutes, preferably for at least 20 minutes, preferably for at least 25 minutes, preferably for at least 30 minutes, preferably for at least 35 minutes, preferably for at least 40 minutes, preferably for at least 45 minutes. Then, the colorant (C) is added with continuous mixing as the final component, and then the solution is preferably mixed for at least 10 minutes, preferably for at least 15 minutes, preferably for at least 20 minutes, preferably for at least 25 minutes, preferably for at least 30 minutes, preferably for at least 35 minutes, preferably for at least 40 minutes, preferably for at least 45 minutes to obtain the inkjet ink. The resulting inkjet ink can then be placed in a printing cartridge, for example, a FUNAI TIJ cartridge manufactured by Funai Co., or other print heads suitable for ketone-based inks.

[0113] Properties The inkjet inks disclosed herein, for example, print a fine line image (e.g., bar code) (1 mm × 1 cm, fine line, monochrome bit map), expose the inkjet ink to air for a specific time (e.g., 30 seconds, 1 minute, 10 minutes, 60 minutes, etc.) (remove the cap of the ink cartridge), reprint the same fine line image, and measure by comparing the image reprinted after removing the cap with the original image to determine whether line dropout / loss of line clarity has occurred in the fine line image, and have an extended decap time. If no line dropout / loss of line clarity occurs at the tested time intervals, the inkjet ink is given a "good" decap score for that time interval. If 1 to 2 lines dropout / loss of clarity occurs at the tested time intervals but does not significantly affect the clarity or readability of the fine line image, the inkjet ink is given an "acceptable" decap score for that time interval. If 3 or more lines dropout / loss of clarity occurs at the tested time intervals, the inkjet ink is classified as "poor" at that time interval. Suitable inkjet inks achieve an "acceptable" or "good" decap classification when decapped (i.e., exposed to air) for 30 seconds, preferably 1 minute, more preferably 10 minutes, even more preferably 30 minutes, and still even more preferably 60 minutes.

[0114] The inkjet inks disclosed herein are also characterized by long-term operating stability (also known as ink life or print life). To test the operating stability of an inkjet ink, a fine line image (e.g., a barcode) (1 mm × 1 cm, fine line, monochromatic bit map) can be printed continuously without interruption over a number of consecutive pages (e.g., printed on 3,000 pages in a continuous printing operation), and the print quality can be evaluated by visually inspecting for nozzle chipping on certain pages (e.g., the 1,000th page, 2,000th page, and 3,000th page) throughout the printing operation. If no line dropout / loss of line clarity occurs on the page being inspected, the inkjet ink is given an operating stability rating of "G" (good) for that page. If 1 to 2 lines dropout / loss of clarity occurs on the page being inspected but does not significantly affect the clarity or readability of the fine line image, the inkjet ink is given an operating stability rating of "A" (acceptable) for that page. If 3 or more lines dropout / loss of clarity occurs on the page being inspected, the inkjet ink is given an operating stability rating of "NG" (bad) for that print. An inkjet ink that maintains a "G" rating or an "A" rating, preferably a "G" rating, when printed over 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 is considered desirable in terms of operating stability (the ability to maintain dispersion / suspension without precipitation / sedimentation and inappropriate jetting).

[0115] The inkjet inks disclosed herein are also characterized by excellent adhesion to a wide variety of substrates. Adhesion is typically tested using a "tape peel test". In this test, an adhesive tape, typically 3M Scotch (registered trademark) tape, particularly Scotch (registered trademark) lightweight packaging tape 600, is applied to the dried printed ink and then peeled off. Good ink adhesion is characterized by little to no ink peeling from the substrate, i.e., little to no ink being detectable on the adhesive tape and / or no detectable change in the printed ink. An "acceptable" rating is characterized by a significant amount of ink peeling from the substrate, i.e., ink being visible on the adhesive tape and / or a significant change, such as reticulation or fading, in the printed ink. A "poor" rating is characterized by a large amount of ink peeling from the substrate, i.e., a large amount of ink being visible on the adhesive tape (there may be a reproduction of the print on the adhesive tape), and / or a significant degradation in print quality, such as reticulation or fading.

[0116] The inkjet inks disclosed herein can also be characterized by long jetting distances. The jetting distance of an inkjet ink can be measured by printing test patterns while increasing the distance between the print head and the substrate and evaluating the print quality at each distance. This can involve printing images such as alphanumeric sequences at various jetting distances (e.g., 2 mm, 4 mm, 6 mm, 8 mm, and 10 mm) and visually evaluating the print quality of the printed images in terms of image clarity, edge sharpness, and accuracy of droplet placement. If the printed image is clearly readable, the edges of the contours are distinct, and the droplet placement is accurate, the inkjet ink is given a "good" jetting distance rating for the tested jetting distance. If the printed image is readable but has some blur, a slight loss of edge sharpness, and / or a slight loss of droplet placement accuracy, the inkjet ink is given an "acceptable" jetting distance rating for the tested jetting distance. If the image lacks clarity, the edges of the contours are not distinct, and / or the droplet placement is inaccurate such that the printed image is unreadable, the inkjet ink is given a "poor" jetting distance rating for the tested jetting distance. Preferred inkjet inks maintain a "good" or "acceptable" jetting distance rating for jetting distances of at least 1 mm, preferably at least 2 mm, preferably at least 3 mm, preferably at least 4 mm, preferably at least 5 mm, preferably at least 6 mm, preferably at least 7 mm, more preferably at least 8 mm, even more preferably at least 9 mm, and still even more preferably at least 10 mm.

[0117] Another advantage of the disclosed inkjet ink is that the optical density can be easily adjusted and regulated to meet consumer requirements, requirements for specific applications, and the like. The optical density of the ink can be measured by printing a solid block image (e.g., 1 cm × 10 cm) and reading the optical density using a spectrophotometer (e.g., X-rite eXact sold by X-rite, density / TVI mode). Since the optical density is a measure of the reflected or absorbed light drawn into the printed surface, the value of the optical density is dimensionless. Inkjet ink that produces an image with a read value of optical density less than 1.90 is considered to result in a low optical density image, while inkjet ink that produces a read value of optical density of 1.90 or more is judged to result in a high optical density image. Typical inkjet inks of the present disclosure result in an image having an optical density of at least 1.90, preferably at least 2.00, preferably at least 2.10, preferably at least 2.20, preferably at least 2.30, preferably at least 2.40, preferably at least 2.50, but can produce optical density values above or below these ranges if desired.

[0118] To test the legibility (opacity) of the inkjet ink on a dark substrate, a solid block image (e.g., 1 cm × 10 cm) can be printed on a dark substrate such as the black portion of a Form 2C opacity chart available from the Leneta Company, Inc. using the inkjet ink. Then, the color difference (indicated by ΔE*ab) between the silver solid block image and the black portion of the Form 2C opacity chart is measured using a suitable colorimeter (e.g., the eXact colorimeter from X-rite) for each CIELAB color space (a* value, b* value, and L* value), and the formula: ΔE*ab = √((ΔL*)2 + (Δa*)2 + (Δb*)2) can be obtained by calculating the color difference according to.

[0119] In this specification, inkjet inks that result in a ΔE*ab value of 10 or more when printed on the black portion of the Form 2C opacity chart are considered desirable in terms of their readability (opacity), while inkjet inks that result in a ΔE*ab value of less than 10 are considered to result in insufficient opacity (unreadable).

[0120] Printed matter Inkjet inks can be printed on a variety of substrates, including flat sheets or webs supplied in three-dimensional parts and roll forms, for the production of a wide variety of printed matter. The flat substrate is a substrate suitable for forming printed matter, but a particular advantage of the present disclosure is that, due to the disclosed inkjet inks (having long flight distance capabilities), the ink has to travel a long distance to reach all parts of complex surfaces, such as substrates having radial, curved, serrated, corrugated, grooved, edged substrates, and / or structured surfaces (e.g., granulated surfaces). It is well known that all are difficult substrates, but it is possible to form a printed image on a complex three-dimensional substrate. Printed matter may be suitable in the graphic arts, textile, packaging (e.g., food packaging, pharmaceutical packaging, etc.), lottery tickets, direct mail, business forms, and publishing industries, examples of which include tags or labels, lottery tickets, publications, packaging (e.g., food packaging, pharmaceutical packaging, blister packaging, various other flexible packaging, etc.), folding cartons, rigid containers (e.g., bottles such as plastic cups or drums, glass containers, metal cans, PET bottles, jars, and tubes), envelopes, corrugated, store displays, etc. Particularly preferred printed matter is that which has a dried form of inkjet ink disposed on a complex three-dimensional portion of the printed matter. For example, the printed image is disposed on a grooved or corrugated portion of a plastic container or on the recessed dome-shaped bottom of a metal can.

[0121] The inkjet ink can be printed on a porous (or permeable) substrate, examples of which include, but are not limited to, uncoated paper, wood, film, corrugated (cardboard / fiberboard), and cloth (e.g., woven cloth, non-woven cloth, and foil laminate cloth).

[0122] The inkjet ink can also be printed on non-porous (or non-permeable) substrates, such as various plastics, glass, metals (e.g., steel, aluminum, etc.), and / or non-permeable paper (e.g., coated paper such as varnish-coated paper). These include, but are not limited to, flat sheets or rolls of molded plastic parts or metal parts and plastic films or metal films. Examples include 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 paper such as varnish-coated paper, and metals such as steel and aluminum.

[0123] Method for forming a printed image The present disclosure provides a method for forming a printed image on a substrate, the method including applying the inkjet ink of one or more embodiments onto the substrate using a drop-on-demand print head and drying the inkjet ink.

[0124] In inkjet printing, when a precise pattern of dots is ejected onto a printing medium from a droplet generation device known as a print head, a desired printed image is formed. The print head is disposed on a nozzle plate and has an array of precisely formed nozzles attached to an inkjet print head substrate. The inkjet print head substrate incorporates an array of firing chambers that receive inkjet ink through fluid communication with one or more ink reservoirs.

[0125] As the printing unit of this method, any drop-on-demand print head known to those skilled in the art of inkjet printing can be used, including thermal print heads, electrostatic print heads, piezoelectric print heads, and acoustic print heads. Preferably, a thermal print head (having a thermal converter) is used.

[0126] Each firing chamber has a resistive element (i.e., a thermal converter) known as a firing resistor, which is disposed on the opposite side of the nozzle such that inkjet ink accumulates between the firing resistor and the nozzle. Each resistive element is typically a pad of resistive material and has a size of, for example, about 35 μm × 35 μm. The print head is held and protected by an enclosure called a print cartridge or inkjet pen. When a specific resistive element is energized, droplets of inkjet ink are ejected through the nozzle towards the printing medium. The ejection of ink droplets is typically under the control of a microprocessor, and the signal from the microprocessor is transmitted to the resistive element via an electrical trace to form alphanumeric and other image patterns on the printing medium. Since the nozzles are small, typically having a diameter of 10 μm to 40 μm, ink that minimizes clogging is desirable. In particular, thermal inkjet (TIJ) is an open-atmosphere print head design (the nozzle orifice is open to the atmosphere and there is no valve seal at the orifice to enable ink pressurization), so TIJ printing has historically suffered from performance degradation during intermittent printing where the decap time (print idle time) causes premature drying of the ink inside and around the nozzles.

[0127] In one or more embodiments, the present disclosure provides a method of forming a printed image by applying an inkjet ink onto the surface of a substrate by a thermal inkjet printhead and drying the inkjet ink. Using the inkjet ink described herein overcomes the problem of short decap times (too high a rate of solvent loss) commonly associated with thermal inkjet processes.

[0128] For example, 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. Printheads generally suitable for use in the methods herein have droplet sizes in the range of 2 to 80 pL and droplet frequencies in the range of 10 to 100 kHz, and high-quality printing can be obtained, for example, by setting the drive voltage to 8.0 to 9.5 volts, the print speed to up to 300 feet per minute, the pulse heating temperature to 25 to 45 °C, and the pulse length to 0.7 to 2.5 microseconds, although values above or below these described values can also be used and still obtain satisfactory printing. One non-limiting example of a printhead suitable for use in the disclosed method is the FUNAI TIJ cartridge manufactured by Funai Electric Co., Ltd.

[0129] After application, the inkjet ink is dried. In some embodiments, external heat may be applied, for example, by using a heater, to dry the applied inkjet ink. However, it is preferred not to apply external heat to facilitate drying or to increase the drying rate. Thus, in a preferred embodiment, drying is achieved by drying the applied inkjet ink under ambient conditions (in air, at about 23° C.) for 30 seconds or less, preferably 25 seconds or less, more preferably 20 seconds or less, even more preferably 15 seconds or less, and still even more preferably 10 seconds or less, without using an external heat source such as a heater. Further, the method of the present disclosure does not require energy curing (e.g., UV or electron beam curing). Once the applied ink is considered dry, a further coating of the inkjet ink may be applied, or any processing step known to those skilled in the art may be performed if desired.

[0130] Also, it should be recognized that in the method of the present specification, before applying the inkjet ink, substrate surface treatments such as corona treatment, atmospheric pressure plasma treatment, and flame treatment can be optionally used to improve print characteristics, such as ink adhesion. Parameters for such substrate surface treatments can vary widely depending on the substrate material being printed, the specific inkjet ink being utilized, the printing method being applied, and the desired characteristics and uses of the printed article.

[0131] The following examples are intended to further illustrate the inkjet ink and are not intended to limit the scope of the claims.

Examples

[0132] Materials Piccolyte A25 is a terpene resin (globular type, SP = 22 - 28 °C) manufactured from α-pinene available from Pinova. DERTOPHENE T160 is a terpene phenol resin (OHV = 60 mg KOH / g, SP = 160 °C, Mw = approximately 1000 g / mol) available from DRT / Pinova. BYK-3550 is a silicone acrylate copolymer surfactant available from BYK Additives & Instruments. OIL BLACK 860 (also known as Solvent Black 3 or SB3) is an organic dye available from Orient Chemical Industries Co., Ltd. Valifast Black 1821 (also known as Solvent Black 7 or SB7) is a nigrosine metal complex dye available from Orient Chemical Industries Co., Ltd. Valifast Black 3830 (also known as Solvent Black 27 or SB27) is a metal complex azo dye available from Orient Chemical Industries Co., Ltd.

[0133] Evaluation Method for Inkjet Ink Preparation of Printed Samples Examples of inkjet inks were evaluated using a FUNAI TIJ cartridge manufactured by Funai Electric Co., Ltd. The inks were evaluated using heat printing technology related to Funai Electric Co., Ltd. (Software and hardware were manufactured by Weber Marking Systems, and the transport table was manufactured by Kirk Rudy).

[0134] Evaluation of Decap Time The printing conditions used to evaluate the decap time were as follows: - Printing substrate; plain (uncoated) paper - Printing resolution: 300 dpi × 300 dpi (vertical × horizontal) - Prefire 450 nsec - Dead time 1200 nsec - Main fire 1500 nsec - Voltage 9.5 V - Pulse heating on (at 35 °C) - Printed image; 100% duty (1 mm × 1 cm, monochrome bitmap, thin line image) (see, for example, FIG. 2).

[0135] The thin line image was printed, and it was confirmed that the printed image did not contain missing or unclear lines (precursor to nozzle clogging or nozzle chipping). After confirmation, the print head was left de-capped for a specific time (30 seconds, 1 minute, 10 minutes, or 60 minutes), and then reprinted using the same thin line image. The reprinted thin line image (after a specific time elapsed) was checked to see if there was any line dropout / loss of line clarity. If no line dropout / loss of line clarity occurred, the inkjet ink was given a "good" de-cap rating over that time interval. If 1 - 2 lines were missing / lost clarity at the tested time interval but did not significantly affect the clarity or readability of the thin line image at the tested time interval, the inkjet ink was given an "acceptable" de-cap rating at that time interval. If 3 or more lines were missing / lost clarity at the tested time interval, the inkjet ink was classified as "bad" at that time interval. The appropriate / desired inkjet ink is one that achieves an "acceptable" or "good" de-cap classification when de-capped (i.e., exposed to air) over each tested time interval.

[0136] Printing life evaluation The printing conditions used to evaluate the operating stability (ability to maintain dispersion / suspension without precipitation / sedimentation) of the inkjet ink during printing operations were as follows: - Printing substrate; uncoated paper (plain paper) - Printing resolution: 300 dpi × 300 dpi (vertical × horizontal) - Printed image; 100% duty (1 mm × 1 cm, monochrome bitmap, thin line image).

[0137] The thin line image was printed continuously 500 times without interruption, and the print quality of the 500th print was determined by checking for any nozzle missing through a visual inspection method. When no line dropout / loss of line clarity occurred, the inkjet ink was given an operating stability rating of "G" (good). When 1 - 2 lines were missing / lost clarity but did not significantly affect the clarity or readability of the thin line image, the inkjet ink was given an operating stability rating of "A" (acceptable). When 3 or more lines were missing / lost clarity, the inkjet ink was given an operating stability rating of "NG" (bad). The appropriate / desired inkjet ink is one that maintains an operating stability rating of "G" or "A" for the 500th print.

[0138] Adhesion evaluation The ink was printed on an LDPE film. One minute after printing, Scotch (registered trademark) lightweight packaging tape 600 was gently pressed against the ink and then immediately peeled off. The performance of the ink was rated according to the descriptions shown in Table 1 below.

[0139]

Table 1

[0140] Examples of inkjet inks Examples of inkjet inks are shown in Table 2. The amounts of each component are represented as weight percentages relative to the total weight (100%) of the inkjet ink.

[0141] * indicates that the example is a comparative example.

[0142] Preparation method To prepare the ink of the example, the resin(s) and any surfactant were first combined with the specified combination of dioxolane and 1-propanol and mixed by a mechanical stirrer for at least 30 minutes. Then, the dye was added to the mixture and mixed for at least 30 minutes to obtain an inkjet ink. Then, the example of the inkjet ink was evaluated using a FUNAI TIJ cartridge manufactured by Funai Electric Co., Ltd.

[0143]

Table 2

[0144] Inkjet ink performance From Table 3, it can be seen that the combination of Valifast Black 3830 (SB27), dioxolane, and terpene resin had a remarkable effect in terms of decapping time, printing life, and adhesiveness (Examples 1, 3, 4, 6, and 9). In contrast, the inkjet inks without dioxolane (Example 11) and the inkjet inks without pinene-based terpene resin (Examples 7 and 12) had inferior performance in each test and were classified as "defective" for all decapping times. Each of these examples was also classified as "defective" for the printing life of 3000 pages and 5000 pages in the case of Example 7 and for all printing life tests in the cases of Examples 11 and 12. Due to these unsatisfactory results, the adhesiveness test was not performed on Examples 11 and 12.

[0145] It was also found that not all colorants are compatible with the dioxolane / terpene system. Inkjet inks without Valifast Black 3830 (Examples 2 and 5) were found to be inappropriate. When the organic dye Oil Black 860 was used, "good" results were shown for all decap times, but the print life and adhesion on LDPE were insufficient (Example 2). When the nigrosine metal complex dye Valifast Black 1821 was used, good adhesion was shown on all substrates tested, but the results were insufficient for all decap times and print life (Example 5).

[0146] Regarding the amount of dioxolane, loadings in the range of 60.9% to 90.9% by weight resulted in acceptable or better decap behavior for all decap times, acceptable or better print life up to 5000 pages, and acceptable or better adhesion on all substrates (Examples 1, 3, 4, 6, 8, 9, and 10). When dioxolane was completely removed, unsatisfactory performance was obtained for all decap time and print life tests (Example 11). When containing 90.9% by weight of dioxolane and no alcohol solvent, almost acceptable results were obtained (Example 4), but better results were obtained when using 15% by weight of 1-propanol, the optimal amount (Examples 1 and 3).

[0147]

Table 3

[0148] When numerical limits or ranges are described herein, the endpoints are included. Also, all values and sub-ranges within the numerical limits or ranges are specifically included as if explicitly described.

[0149] As used herein, words such as "a" and "an" have the meaning of "one or more".

[0150] The present disclosure also contemplates other embodiments that “comprise,” “consist of,” and “consist essentially of” the embodiments or elements presented herein, whether or not explicitly recited.

[0151] In light of the above teachings, it will be apparent that numerous modifications and variations of the present invention are possible. Accordingly, it is to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.

[0152] All of the above patents and other references are hereby incorporated by reference into this specification in their entirety as if each were specifically and fully set forth herein.

Claims

1. (A1) a terpene resin, and (B) a solvent system containing (B1) dioxolane, and (C) a colorant containing a metal complex azo dye, An inkjet ink comprising.

2. The inkjet ink according to claim 1, wherein the terpene resin (A1) is present in an amount of 0.1 to 10% by weight based on the total weight of the inkjet ink.

3. The inkjet ink according to claim 1, wherein the terpene resin (A1) is a homopolymer produced from α-pinene.

4. The inkjet ink according to claim 1, wherein the dioxolane (B1) is present in an amount of 2 to 98% by weight based on the total weight of the inkjet ink.

5. The inkjet ink according to claim 1, wherein the solvent system (B) further comprises an alcohol solvent (B2).

6. The inkjet ink according to claim 5, wherein the alcohol solvent (B2) is present in an amount of 0.5 to 60% by weight based on the total weight of the inkjet ink.

7. The inkjet ink according to claim 5, wherein the weight ratio ((B1):(B2)) of dioxolane (B1) to the alcohol solvent (B2) is 0.25:1 to 30:

1.

8. The inkjet ink according to claim 1, wherein the weight ratio ((B1):(A1)) of dioxolane (B1) to the terpene resin (A1) is 20:1 to 250:

1.

9. The inkjet ink according to claim 1, wherein the solvent system (B) substantially does not contain methyl ethyl ketone.

10. The inkjet ink according to claim 9, wherein the solvent system (B) does not contain methyl ethyl ketone.

11. The metal complex azo dye is a metal center, and (E)-1-((2-methoxy-5-nitrophenyl)diazenyl)naphthalene-2-ol or its deprotonated form, demethylated form, deprotonated and demethylated form, tautomer, or stereoisomer, A metal complex containing, the inkjet ink according to claim 1.

12. The inkjet ink according to claim 11, wherein the metal center is a chromium ion.

13. The inkjet ink according to claim 1, wherein the colorant (C) is present in an amount of 0.5 to 20% by weight based on the total weight of the inkjet ink.

14. The inkjet ink according to claim 1, further comprising (A2) a terpene phenol resin.

15. The inkjet ink according to claim 14, wherein the terpene phenol resin (A2) is present in an amount of 0.01 to 10% by weight based on the total weight of the inkjet ink.

16. The inkjet ink according to claim 1, further comprising (D) a surfactant.

17. The inkjet ink according to claim 16, wherein the surfactant (D) is present in an amount of 0.01 to 5% by weight based on the total weight of the inkjet ink.

18. The inkjet ink according to claim 16, wherein the surfactant (D) is a silicone acrylate copolymer.

19. A printed matter comprising a substrate and a dried form of the inkjet ink according to claim 1 disposed on the substrate.

20. A method of forming a printed image on a substrate, comprising: applying the inkjet ink according to claim 1 onto the substrate using a thermal inkjet print head; drying the inkjet ink. The method comprising the steps above.

Images