Inkjet inks for side-jet printing

Abstract

An inkjet ink for side fire printing includes an unsaturated fatty acid, a first linear alkane 1, 2-diol having a carbon chain of 2 to 4 carbon atoms, a second linear alkane 1, 2-diol having a carbon chain of 5 to 14 carbon atoms, and an organic solvent. The inkjet ink is characterized by an extended uncapping time even under various environmental conditions when printed on a vertical surface, in addition to good operational stability and drying time. A method of forming a printed image by side fire printing with a thermal inkjet printhead is also provided.

Description

Technical Field

[0001] This invention relates to inkjet inks for side-printing, particularly inkjet inks formulated with fatty acids, two straight-chain alkane 1,2-diols, and organic solvents. Background Technology

[0002] The “background” description provided herein is intended to provide a general overview of the context of this disclosure. Within the scope of this background section, the work of the inventors and any descriptions that may not conform to the prior art at the time of submission are not expressly or impliedly acknowledged as prior art to this invention.

[0003] Thermal inkjet (TIJ) printing is an ideal technology for printing, coding, and marking because it offers high print resolution at a lower cost than competing technologies in the field, such as continuous inkjet (CIJ) methods. In the thermal inkjet printing process, the print cartridge contains a series of tiny chambers, each containing a heater, which generates ink droplets through the thermal evaporation of the ink solvent. During ejection, a resistor is rapidly heated to generate bubbles (hence the term "bubble ejection"), which are then ejected from the orifice as ink droplets. This process is extremely efficient and repeatable, and modern TIJ printheads for industrial graphics applications are capable of producing uniform ink droplets with volumes below 4 pL at frequencies above 36 kHz.

[0004] However, industrial marking and coding often require printing basic information such as personal information, labels, codes, dates (e.g., expiration dates), and traceability information (e.g., manufacturing batches) on substrates that may be vertical or slanted. This printing method, which involves horizontally ejecting ink, is known as "side-jet printing." Industrial environments may also require side-jet printing on a variety of substrates, such as packages and bottles. This printing can be performed under various environmental conditions, such as printing in cold storage to label refrigerated foods or printing in warm outdoor environments to mark wood products. Furthermore, thermal inkjet printing can suffer from poor reliability after a period of inactivity. For example, some inkjet inks have very short decap times, where solvent loss due to prolonged exposure to air inside an uncapped printhead leads to nozzle clogging / blockage, resulting in unreliable inkjet printing and a decline in image quality over time. Because side-jet printing involves ejecting ink laterally, residual ink is more likely to accumulate on the printhead. Therefore, the image quality degradation caused by short decap times is exacerbated by side-jet printing. Poor image quality is unacceptable for many applications, especially for marking and encoding basic information. For this reason, despite other advantages, TIJ technology has limited acceptance in marking / encoding applications and is constrained by environmental conditions and printing on horizontal substrates.

[0005] U.S. Patent Application US20220064472 (also filed as JP-A-2022-037408) describes an ink composition and a processing liquid composition. Both compositions are applied to a printing medium by an ink jetting method. The ink composition is an aqueous composition containing a coloring material and a surfactant. The processing liquid composition is an aqueous composition containing a flocculant and a surfactant. Each composition contains a silicone surfactant, and either the ink composition or the processing liquid composition contains a nitrogen-containing solvent, a sulfur-containing solvent, or a cyclic ester. This patent application does not consider side-spray printing or cap-opening time.

[0006] U.S. Patent Application US20160333209 (also published as WO2015 / 125368) describes an ink composition comprising an amide having a specific molecular weight, a colorant, a polymer with an SP value of 17 to 24, and water, wherein a specific relationship exists between the log P value of the amide and the SP value of the polymer. An ink jet recording method involves jetting the ink composition onto a recording medium that may have been acid-treated. This patent application does not consider side-printing or cap-opening times. Summary of the Invention

[0007] In view of the above, there is a need for an inkjet ink for side-printing that has an extended cap opening time over a certain temperature and humidity range.

[0008] Therefore, one object of the present invention is to provide novel inkjet inks that meet these standards.

[0009] Another object of this disclosure is to provide a novel method for forming a printed image on a substrate by side-printing inkjet ink onto the substrate and drying it.

[0010] The inventors have discovered that the inkjet inks used for side-printing are characterized by extended cap-opening time and good operational stability under various environmental conditions, thereby achieving these and other objectives, which will become apparent in the detailed description below.

[0011] Therefore, the present invention provides:

[0012] (1) An inkjet ink for printing by side-jetting onto a substrate using an inkjet printhead, wherein,

[0013] The inkjet ink comprises:

[0014] (A) Fatty acids that contain unsaturated fatty acids;

[0015] (B1) A first straight-chain alkane, 1,2-diol, having a carbon chain of 2 to 4 carbon atoms;

[0016] (B2) A second straight-chain alkane, 1,2-diol, having a carbon chain of 5 to 14 carbon atoms;

[0017] (C) Organic solvents; and

[0018] (D) Water,

[0019] Wherein, based on the total weight of the inkjet ink, the contents of the first straight-chain alkane 1,2-diol (B1) and the second straight-chain alkane 1,2-diol (B2) are each independently 0.1 to 10 wt.

[0020] (2) The inkjet ink according to (1), wherein the organic solvent (C) comprises dimethyl sulfone or 2-pyrrolidone, and the content of dimethyl sulfone or 2-pyrrolidone in the inkjet ink is 2 to 20 wt% based on the total weight of the inkjet ink.

[0021] (3) The inkjet ink according to (1) or (2), wherein the organic solvent (C) comprises dimethyl sulfone.

[0022] (4) The inkjet ink according to any one of (1) to (3), wherein the water (D) content is 40 to 80 wt% based on the total weight of the inkjet ink.

[0023] (5) The inkjet ink according to any one of (1) to (4), wherein the content of fatty acid (A) is 0.1 to 5 wt% based on the total weight of the inkjet ink.

[0024] (6) The inkjet ink according to any one of (1) to (5), wherein the fatty acid (A) comprises oleic acid and / or linoleic acid.

[0025] (7) The inkjet ink according to any one of (1) to (6), wherein, based on the total weight of the inkjet ink, the content of the combination of the first straight-chain alkane 1,2-diol and the second straight-chain alkane 1,2-diol ((B1) + (B2)) in the inkjet ink is 5 to 20 wt%.

[0026] (8) An inkjet ink according to any one of (1) to (7), wherein the first straight-chain alkane 1,2-diol (B1) is 1,2-propanediol, and

[0027] The second straight-chain alkane 1,2-diol (B2) is 1,2-hexanediol.

[0028] (9) The inkjet ink according to (8), wherein the weight ratio of 1,2-propanediol to 1,2-hexanediol is 1:1 to 10:1.

[0029] (10) The inkjet ink according to any one of (1) to (9), wherein the inkjet ink further comprises (E) alkanolamine.

[0030] (11) The inkjet ink according to (10), wherein the content of the alkanolamine (E) is 0.01 to 5 wt% based on the total weight of the inkjet ink.

[0031] (12) The inkjet ink according to (10) or (11), wherein the alkanolamine (E) is at least one selected from ethanolamine, propanolamine, isopropanolamine, diethanolamine and triethanolamine.

[0032] (13) The inkjet ink according to any one of (1) to (12), wherein the inkjet ink further comprises one or more surfactants (F) in an amount of 0.01 to 5 wt% based on the total weight of the inkjet ink.

[0033] (14) The inkjet ink according to any one of (1) to (13), wherein the inkjet ink further comprises (G) a colorant.

[0034] (15) The inkjet ink according to (14), wherein the content of the colorant (G) is 0.1 to 30 wt% based on the total weight of the inkjet ink.

[0035] (16) The inkjet ink according to any one of (1) to (15), wherein the inkjet ink further comprises one or more glycol ethers (H) in a total content of 0.1 to 5.0 wt% based on the total weight of the inkjet ink.

[0036] (17) A method for forming a printed image on a substrate by side-printing, wherein the method includes:

[0037] The inkjet ink of any one of (1) to (16) is applied laterally to the substrate using a thermal inkjet printhead; and

[0038] Dry the inkjet ink.

[0039] (18) According to the method of (17), wherein the minimum angle between the straight line of the shortest distance between the nozzle of the thermal inkjet printhead supplying the inkjet ink and the substrate and the direction of gravity is in the range of 70° to 90°. Attached Figure Description

[0040] A more complete understanding of this disclosure and its many accompanying advantages will be readily obtained when considered in conjunction with the accompanying drawings, by referring to the following detailed description, in which:

[0041] Figure 1A The inkjet nozzles are shown after side-jet printing with regular inkjet ink.

[0042] Figure 1B The inkjet nozzle is shown after side-jet printing with the inkjet ink of the present invention.

[0043] Figure 1C The inkjet nozzle is shown after side-jet printing with the inkjet ink of the present invention.

[0044] Figure 2A An initial side-printed image using typical inkjet inks is shown, with arrows added to indicate the printing direction.

[0045] Figure 2B Shown in Figure 2A Subsequent side-printing with typical inkjet inks was performed 30 minutes after printing without wiping the printhead.

[0046] Figure 3A An initial side-printing using the inkjet ink of the present invention is shown, with arrows added to indicate the printing direction.

[0047] Figure 3B Shown in Figure 3A Subsequent side-printing was performed using the inkjet ink of the present invention 30 minutes after printing without wiping the printhead. Detailed Implementation

[0048] In the following description, it should be understood that other implementations may be used, and structural and operational changes may be made without departing from the scope of the embodiments disclosed herein.

[0049] The following definitions will provide a better understanding of this disclosure. As used herein, the words “a” and “an” have the meanings of “one or more” and “at least one”. Unless otherwise stated, in the description of this disclosure, if a numerical limitation or range is specified, the endpoints are included. It should also be understood that the terms “comprises” and / or “comprising” as used herein mean the presence of the specified feature, integer, step, operation, element, and / or component, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or combinations thereof.

[0050] This disclosure also contemplates other embodiments or elements described herein that are "comprising," "consisting of," or "essentially composed of," whether or not explicitly stated. Clearly, many modifications and variations of the invention are possible based on the foregoing teachings. Therefore, it should be understood that the invention can be practiced in ways other than those specifically described herein within the scope of the appended claims. All the foregoing patents and other references are incorporated herein by reference in their entirety as if described in detail.

[0051] As used herein, the words “about,” “approximately,” or “substantially similar” may be used to describe the magnitude and / or location of a numerical value to indicate that the described numerical value and / or location is within a reasonably expected range of the numerical value and / or location. For example, a numerical value may be ±0.1%, ±1%, ±2%, ±5%, ±10%, ±15%, or ±20% of a specified numerical value (or range). Unless otherwise stated, in the description of this disclosure, if a numerical limit or range is specified, the endpoints are included. Furthermore, all values ​​and subranges within a numerical limit or range are explicitly included as if explicitly written.

[0052] Unless otherwise stated, the phrase “substantially free” describes that the amount of a particular component in the inkjet ink is less than 1 wt% relative to the total weight of the inkjet ink, preferably less than 0.5 wt%, more preferably less than 0.1 wt%, even more preferably less than 0.05 wt%, and even more preferably 0 wt%.

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

[0054] As used herein, “compound” refers to a chemical entity, whether solid, liquid or gas, and whether it is in a crude mixture or separated and purified.

[0055] Unless otherwise stated, the term "alkyl" as used herein refers to a straight-chain, branched, or cyclic aliphatic segment having at least one, preferably at least two, preferably at least three, preferably at least four carbon atoms, and at most 22, preferably at most 20, preferably at most 18, preferably at most 12, preferably at most eight carbon atoms. Examples of alkyl groups include, but are not limited to, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, isopentyl, neopentyl, hexyl, isohexyl, 3-methylpentyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl, lauryl, myristyl, cetyl, stearoyl, etc., including Guerbert-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-undecylpentadecanyl). A cycloalkyl group is a cyclic alkyl group. Exemplary cycloalkyl groups include, but are not limited to, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, norbornyl, and adamantyl.

[0056] As used herein, the term "fatty acid" describes a compound having a long-chain (linear) hydrophobic moiety consisting of hydrogen and arbitrarily 8 to 30 carbon atoms, which may be fully saturated or partially unsaturated.

[0057] As used herein, the term "aryl" refers to an aromatic group containing only carbon in an aromatic ring, such as phenyl, biphenyl, naphthyl, anthracene, etc.

[0058] As used herein, the term "aralkyl" refers to a straight-chain, branched, or cycloalkyl moiety (as defined above) substituted with an aryl group (as described above). The aryl group itself may optionally be substituted with 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, etc.

[0059] The term "(meth)acrylate" is used herein to refer to both acrylate and methacrylate groups. In other words, this term should be interpreted as "methyl" being optional. Furthermore, the term "(meth)acrylate" is generally used to refer to both acrylic compounds and acrylate compounds.

[0060] Throughout this specification, the term "boiling point" (bp) refers to the boiling point of a liquid as measured at atmospheric pressure at sea level (i.e., 760 mmHg or 1 atm), also known as the normal boiling point, unless otherwise stated. The term "melting point" (mp) refers to the melting point of a solid as measured at atmospheric pressure at sea level (i.e., 760 mmHg or 1 atm).

[0061] The term "capping behavior" in this article refers to the ability of inkjet ink to be easily ejected from the printhead after prolonged exposure to air. Inkjet ink "capping time" refers to the amount of time an inkjet printhead may remain uncapped before the printer nozzles cease to fire correctly, which can be due to blockage or clogging during print resumption. Typically, nozzles can become clogged (i.e., hindered, slowed) or blocked (i.e., blocked, substantially or completely shut off) due to the formation of sticky plugs within and / or around the nozzle, ink crusting, and / or fouling of various ink components. If a nozzle is blocked, the ink droplets ejected through the nozzle orifice may be misdirected, which can adversely affect print quality. When the orifice is blocked, it becomes substantially or completely blocked. Because the nozzle is blocked, ink droplets may not pass through the affected nozzle. Therefore, the standard for measuring a nozzle's inability to fire is that the ink is misdirected to a greater or lesser degree through the nozzle orifice, or completely blocked, which can be measured by visually inspecting the printed image.

[0062] Inkjet ink

[0063] This disclosure relates to inkjet inks that have appropriate physical and chemical stability for side-jet printing at both ambient and printhead operating temperatures, reliable jetting, extended capping time under various environmental conditions, rapid drying after application to substrates, and good operational stability.

[0064] This invention aims to address issues such as staining during continuous printing and short cap opening times. These two characteristics may be related but may be caused by different factors.

[0065] First, stains during continuous printing are caused by ink buildup around the nozzle. Without being bound by any specific theory, it is speculated that the anionic portion of trans-oleic acid or fatty acids, which are liquid at 25°C, adsorbs onto the nozzle surface, causing the hydrophobic portion to face outwards. This makes the nozzle surface hydrophobic, thus reducing the wettability of water-based inks. Therefore, the ink becomes more difficult to wet and spread across the nozzle surface. Because the ink cannot wet and spread, the nozzle surface remains clean. For example, Figure 1A This shows the ink buildup on the nozzle surface after printing with ordinary inkjet ink, while Figure 1B The image shows a clean nozzle surface with no ink buildup after printing with the inkjet ink of the present invention. While this is not yet certain, it is presumed that the solvent affects the orientation of unsaturated fatty acids relative to the first diol. Since the second diol (B2) is likely more hydrophobic than the first diol (B2), it is conceivable that adding a large amount of the second diol would reduce the activity of oleic acid, and no effect was observed.

[0066] By adding dimethyl sulfone or 2-pyrrolidone as a drying inhibitor to the inkjet ink composition, the capping time can be improved (i.e., the capping time is prolonged). The second diol is likely more hydrophobic than the first diol, thus tending towards the ink-air interface, and has a higher boiling point, thereby inhibiting excessive evaporation of water (capping agent). It is speculated that these factors work together to achieve optimal performance. Furthermore, since ink smudges around the nozzle also affect performance, it is speculated that the results are correlated with smudge assessment results.

[0067] The inkjet inks disclosed herein typically comprise the following components: (A) unsaturated fatty acids; (B1) a first straight-chain alkane 1,2-diol having a carbon chain of 2 to 4 carbon atoms; (B2) a second straight-chain alkane 1,2-diol having a carbon chain of 5 to 14 carbon atoms; (C) an organic solvent; and (D) water. Based on the total weight of the inkjet ink, the first and second straight-chain alkane 1,2-diols (B1, B2) are each present independently in an amount of 0.1 to 10 wt%.

[0068] The inkjet ink disclosed herein may optionally contain one or more of (E) alkanolamine, (F) surfactant, (G) colorant, and (H) glycol ether.

[0069] (A) Fatty acids

[0070] The inkjet ink disclosed herein is formulated with fatty acid (A). Generally, considering operational stability during side-firing and long cap-opening times, the amount of fatty acid (A) used relative to the total weight of the inkjet ink is preferably at least 0.10 wt%, at least 0.15 wt%, at least 0.20 wt%, at least 0.25 wt%, at least 0.30 wt%, at least 0.35 wt%, at least 0.40 wt%, at least 0.45 wt%, at least 0.50 wt%, at least 0.75 wt%, at least 1.0 wt%, at least 1.1 wt%, at least 1.2 wt%, at least 1.5 wt%, at least 2.0 wt%, at least 2.5 wt%, at least 3.0 wt%, at least 3.5 wt%, at least 4.0 wt%, at least 4.5 wt%, and / or preferably up to 5.0 wt%, up to 4.5 wt%, up to 4.0 wt%, up to 3.5 wt%, up to 3.0 wt%, up to 2.5 wt%, up to 2.0 wt%, and up to 1.5 wt%. wt%, up to 1.2 wt%, up to 1.1 wt%, up to 1.0 wt%, up to 0.75 wt%, up to 0.50 wt%, up to 0.45 wt%, up to 0.40 wt%, up to 0.35 wt%, up to 0.30 wt%, up to 0.25 wt%, up to 0.20 wt%, up to 0.15 wt%.

[0071] In one embodiment, the fatty acid may be an unsaturated fatty acid. Unsaturated fatty acids include, but are not limited to, erucic acid (22:1), linoleic acid (18:2), linoleic acid (18:2), vaccenic acid (18:1), elaidic acid (18:1), oleic acid (18:1), sapienic acid (16:1), palmitoleic acid (16:1), and myristoleic acid (14:1). In another embodiment, the inkjet ink is formulated with unsaturated fatty acids as fatty acid (A), and also contains saturated fatty acids, including but not limited to stearic acid (18:0), heptadecanoic acid (17:0), palmitic acid (16:0), pentadecanoic acid (15:0), myristic acid (14:0), tridecanoic acid (13:0), lauric acid (12:0), undecanoic acid (11:0), decanoic acid (10:0), nonanoic acid (9:0), and octanoic acid (8:0). In one embodiment, when unsaturated fatty acids and saturated fatty acids are present in the inkjet ink, the weight ratio of unsaturated fatty acids to saturated fatty acids is preferably from 1:1 to 100:1, preferably from 5:1 to 50:1, more preferably from 10:1 to 30:1, and even more preferably from 15:1 to 25:1.

[0072] From the perspective of operational stability during side-firing and long open-cap time, it is preferable that the fatty acid is liquid at room temperature, for example, the melting point of the fatty acid is not higher than 25°C. In one embodiment, from the perspective of operational stability during side-firing and long open-cap time, the fatty acid comprises oleic acid and / or linoleic acid, both of which have melting points below 25°C. Oleic acid may be Lunac® OV obtained from KaoChemicals. In one embodiment, the fatty acid comprises trans-oleic acid. From the perspective of operational stability during side-firing and long open-cap time, in a preferred embodiment, fatty acid (A) comprises oleic acid.

[0073] (B) Straight-chain alkane 1,2-diol

[0074] In one embodiment, the inkjet ink comprises a first straight-chain alkane 1,2-diol (B1) and a second straight-chain alkane 1,2-diol (B2) different from the first straight-chain alkane 1,2-diol. The first and second straight-chain alkane 1,2-diols can be used independently, and from the perspective of operational stability during side-jet printing and long cap-opening time, their usage relative to the total weight of the inkjet ink is preferably at least 0.1 wt%, at least 0.5 wt%, at least 1.0 wt%, at least 1.5 wt%, at least 2.0 wt%, at least 2.5 wt%, at least 3.0 wt%, at least 3.5 wt%, at least 4.0 wt%, at least 4.5 wt%, at least 5.0 wt%, at least 5.5 wt%, at least 6.0 wt%, at least 6.5 wt%, at least 7.0 wt%, at least 7.5 wt%, at least 8.0 wt%, at least 8.5 wt%, at least 9.0 wt%, at least 9.5 wt%, and / or preferably up to 10 wt%. Maximum 9.5 wt%, maximum 9 wt%, maximum 8.5 wt%, maximum 8 wt%, maximum 7.5 wt%, maximum 7 wt%, maximum 6.5 wt%, maximum 6 wt%, maximum 5.5 wt%, maximum 5 wt%, maximum 4.5 wt%, maximum 4 wt%, maximum 3.5 wt%, maximum 3.5 wt%, maximum 2.5 wt%, maximum 2 wt%, maximum 1 wt%.

[0075] In a preferred embodiment, the content of the first straight-chain alkane 1,2-diol (B1) is 0.1 to 10 wt% based on the total weight of the inkjet ink, and the content of the second straight-chain alkane 1,2-diol (B2) is 0.1 to 10 wt%.

[0076] In one embodiment, considering operational stability during side-firing and long cap-opening time, the combined concentration ((B1) + (B2)) of the first and second linear alkane 1,2-diols in the inkjet ink, relative to the total weight of the inkjet ink, is preferably at least 5 wt%, at least 6 wt%, at least 7 wt%, at least 8 wt%, at least 9 wt%, at least 10 wt%, at least 11 wt%, at least 12 wt%, at least 13 wt%, at least 14 wt%, at least 15 wt%, at least 16 wt%, at least 17 wt%, at least 18 wt%, at least 19 wt%, and / or preferably at most 9 wt%, at most 8 wt%, at most 7 wt%, at most 6 wt%.

[0077] In one embodiment, the first and second straight-chain alkane 1,2-diols each independently comprise a carbon chain of 2 to 14 carbon atoms, preferably 3 to 14 carbon atoms, more preferably 3 to 10 carbon atoms, and even more preferably 3 to 8 carbon atoms.

[0078] In a preferred embodiment, considering operational stability during side-firing and long cap-opening time, the first straight-chain alkane 1,2-diol (B1) is 1,2-propanediol, and the second straight-chain alkane 1,2-diol (B2) is 1,2-hexanediol. In another preferred embodiment, considering operational stability during side-firing and long cap-opening time, the concentration of 1,2-propanediol in the inkjet ink relative to the total weight of the inkjet ink is preferably at least 4 wt%, at least 5 wt%, preferably at least 6 wt%, more preferably at least 7 wt%, and / or preferably at most 9 wt%, at most 8.5 wt%, at most 8 wt%. In a preferred embodiment, considering the operational stability during side-firing and the long cap-opening time, the content of 1,2-hexanediol relative to the total weight of the inkjet ink is preferably at least 2 wt%, at least 2.5 wt%, preferably at least 3 wt%, preferably at least 3.5 wt%, and / or preferably at most 6 wt%, at most 5.5 wt%, preferably at most 5 wt%, preferably at most 4.5 wt%.

[0079] In one embodiment, considering the operational stability during side-firing and the long open-cap time, the first straight-chain alkane 1,2-diol (B1) is 1,2-propanediol, and the second straight-chain alkane 1,2-diol (B2) is 1,2-hexanediol. The weight ratio of 1,2-propanediol to 1,2-hexanediol in the inkjet ink is preferably at least 1:1, at least 1.1:1, at least 1.5:1, at least 1.7:1, and preferably at most 10:1, at most 9:1, at most 8:1, at most 7:1, or at most 5:1.

[0080] In one embodiment, the weight ratio of 1,2-propanediol to 1,2-hexanediol in the inkjet ink is preferably from 1:1 to 10:1, more preferably from 1.5:1 to 9:1, more preferably from 1.7:1 to 8:1, and even more preferably from 1.7:1 to 2:1.

[0081] (C) Organic solvents

[0082] In many printing processes that use solvent-based inks, especially thermal inkjet printing, the selection of a suitable organic solvent can affect the reliability of the printing process, the performance / appearance of the printed ink product, and the overall efficiency of the printing process. For example, in thermal inkjet printing, the choice of organic solvent can: 1) help form bubbles during the jetting process, thereby achieving reliable inkjet printing; 2) affect the stability / volatility of the inkjet ink by altering the interaction dynamics between the organic solvent and various inkjet ink components, thereby affecting cap opening behavior, scaling, and / or droplet trajectory; 3) affect the adhesion, abrasion and scratch resistance, and optical density characteristics of the printed image through the interaction forces between the organic solvent and other inkjet ink components, even if the organic solvent may no longer be present or may be present in reduced amounts after drying; 4) affect the drying time after coating or the equipment required to dry the coated ink; and / or 5) affect droplet dynamics.

[0083] In one embodiment, the organic solvent (C) may include one or more diol cosolvents, dimethyl sulfone, or 2-pyrrolidone.

[0084] The diol cosolvent may contain at least 2 carbon atoms, preferably at least 3 carbon atoms, and at most 10 carbon atoms, preferably at most 8 carbon atoms, more preferably at most 6 carbon atoms, even more preferably at most 5 carbon atoms, and even more preferably at most 4 carbon atoms. The preferred organic solvent (C) is an organic solvent containing two hydroxyl groups attached to adjacent carbon atoms (i.e., vicinal diol).

[0085] Examples of organic solvents (C) include, but are not limited to, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, butanediol, neopentyl glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,2-pentanediol, 2,4-pentanediol, 1,6-hexanediol, 2,5-hexanediol, 1,7-heptanediol, 1,2-octanediol, and 1,8-octanediol, which may be used alone or in combination.

[0086] In a preferred embodiment, the organic solvent (C) is selected from at least one of ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, butanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol and 2,3-butanediol, more preferably ethylene glycol, propylene glycol or both.

[0087] To improve the performance of inkjet inks, such as cap opening performance and print quality, without significantly prolonging ink drying time, the boiling point of the organic solvent (C) is preferably from 188°C to below 250°C, more preferably below 240°C, more preferably below 230°C, more preferably below 220°C, more preferably below 210°C, and even more preferably below 200°C. In view of the above, ethylene glycol, propylene glycol, or both are preferred herein.

[0088] When used, based on the total weight of the inkjet ink, the content of organic solvent (C) in the inkjet ink may be at least 1 wt%, preferably at least 3 wt%, preferably at least 5 wt%, preferably at least 7 wt%, preferably at least 9 wt%, preferably at least 11 wt%, more preferably at least 13 wt%, even more preferably at least 15 wt%, even more preferably at least 17 wt%, and at most 40 wt%, preferably at most 38 wt%, preferably at most 36 wt%, preferably at most 34 wt%, preferably at most 32 wt%, preferably at most 30 wt%, preferably at most 28 wt%, preferably at most 26 wt%, more preferably at most 24 wt%, even more preferably at most 22 wt%, even more preferably at most 20 wt%.

[0089] In addition to the solvents mentioned above, the solvent system may optionally contain one or more other organic solvents.

[0090] Examples of other organic solvents include, but are not limited to:

[0091] - Polyols (in addition to the aforementioned trimethylenediol (B) and 1,2-hexanediol (C)), such as glycerol; and

[0092] - A mixture of two or more polyols.

[0093] From the perspective of long open time, the content of organic solvent (C) in inkjet ink relative to the total weight of inkjet ink may be at least 2 wt%, at least 3 wt%, at least 4 wt%, at least 5 wt%, at least 6 wt%, at least 7 wt%, at least 8 wt%, at least 9 wt%, at least 10 wt%, at least 11 wt%, at least 12 wt%, at least 13 wt%, at least 14 wt%, at least 15 wt%, at least 16 wt%, at least 17 wt%, at least 18 wt%, at least 19 wt%, and / or up to 20 wt%, up to 19 wt%, up to 18 wt%, up to 17 wt%, up to 16 wt%, up to 15 wt%, up to 14 wt%, up to 13 wt%, up to 12 wt%, up to 11 wt%, up to 10 wt%, up to 9 wt%, up to 8 wt%, up to 7 wt%, and up to 6 wt%.

[0094] In a preferred embodiment, considering the long open time, the organic solvent (C) comprises dimethyl sulfone and / or 2-pyrrolidone, preferably dimethyl sulfone.

[0095] (D) Water

[0096] In one embodiment, the inkjet ink comprises water (D). The water may be tap water, distilled water, double-distilled water, deionized water, deionized distilled water, reverse osmosis water, and / or other types of water. In one embodiment, the water is treated with double distillation or reverse osmosis to remove trace metals. The water is preferably double-distilled water, deionized water, deionized distilled water, or reverse osmosis water, and has a conductivity of less than 10 μS·cm at 25°C. -1 Preferably less than 1 μS·cm -1 The resistivity is greater than 0.1 MΩ·cm, preferably greater than 1 MΩ·cm, more preferably greater than 10 MΩ·cm; the total solids concentration is less than 5 mg / kg, preferably less than 1 mg / kg; and the total organic carbon concentration is less than 1000 μg / L, preferably less than 200 μg / L, more preferably less than 50 μg / L. The water is preferably deionized water.

[0097] In one embodiment, the water content in the inkjet ink, relative to the total weight of the inkjet ink, may be at least 40 wt%, at least 42 wt%, at least 44 wt%, at least 45 wt%, at least 46 wt%, at least 48 wt%, at least 50 wt%, at least 52 wt%, at least 54 wt%, at least 55 wt%, at least 56 wt%, at least 58 wt%, at least 60 wt%, at least 62 wt%, at least 64 wt%, at least 65 wt%, at least 66 wt%, at least 68 wt%, at least 70 wt%, and / or preferably at most 80 wt%, at most 75 wt%, at most 70 wt%, at most 68 wt%, at most 66 wt%, at most 65 wt%, at most 64 wt%, at most 62 wt%, at most 60 wt%, at most 58 wt%, at most 56 wt%, at most 55 wt%, at most 54 wt%, at most 52 wt%, at most 50 wt%. wt%, up to 48wt%, up to 46wt%.

[0098] (E) Alkylamine

[0099] In one embodiment, the inkjet ink also comprises an alkanolamine (E). Alkanolamines are alkane compounds containing both a hydroxyl (-OH) group and an amine (primary, secondary, or tertiary) group.

[0100] In some embodiments, the alkanolamine (E) has a total of at least 2 carbon atoms, at least 3 carbon atoms, at least 4 carbon atoms, and / or at most 8 carbon atoms, at most 7 carbon atoms, at most 6 carbon atoms, and at most 5 carbon atoms. In a preferred embodiment, the alkanolamine (E) has 3 carbon atoms.

[0101] In a preferred embodiment, the alkanolamine (E) used in the inkjet inks herein has the following general formula II:

[0102]

[0103] Wherein, X, Y and Z are independently selected from hydrogen; C1-C5 alkyl, preferably C2-C3 alkyl; and alkanoyl, preferably C2-C5 alkanoyl, more preferably C3-C4 alkanoyl; and at least one of X, Y and Z is alkanoyl (an alkyl substituent with at least one hydroxyl group).

[0104] In some embodiments, one of X, Y, and Z is an alkylol group. In some embodiments, two of X, Y, and Z are alkylol groups. In some embodiments, X, Y, and Z are all alkylol groups.

[0105] Regarding the one or more alkyl groups, the alkyl chain may include branches. Alternatively, the alkyl chain of the alkyl group may be straight (without alkyl branches). In a preferred embodiment, the alkyl group is based on a straight-chain alkyl chain. Furthermore, the hydroxyl-containing carbon of the alkyl group may be a primary, secondary, or tertiary carbon; preferably, the hydroxyl-containing carbon is a primary or secondary carbon.

[0106] Alkanolamines (E) can contain primary amino groups (i.e., two of X, Y, and Z are hydrogen), secondary amino groups (i.e., one of X, Y, and Z is hydrogen), or tertiary amino groups (i.e., none of X, Y, and Z are hydrogen). When using an alkanolamine (E) containing a secondary amino group, the two non-hydrogen substituents can be the same or different alkanoyl groups, preferably the same alkanoyl group, as in the case of diethanolamine. When using an alkanolamine (E) containing a tertiary amino group, the three non-hydrogen substituents can be the same or different alkanoyl groups, preferably the same alkanoyl group, as in the case of triethanolamine.

[0107] Suitable examples of alkanolamines (E) include, but are not limited to, isopropanolamine, ethanolamine, N-methylethanolamine, N,N-dimethylethanolamine, N-ethylethanolamine, N-propylethanolamine, N-isopropylethanolamine, N,N-diisopropylethanolamine, N-butylethanolamine, diethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, triethanolamine, propanolamine (3-amino-1-propanol), N-methylpropanolamine, N,N-dimethylpropanolamine, dipropanolamine, tripropanolamine, N,N-dimethylisopropanolamine, diisopropanolamine, triisopropanolamine, 2-amino-2-methyl-1-propanol, 2-amino-2-ethyl-1,3-propanediol, 4-amino-1-butanol, 2-amino-1-butanol, sec-butanolamine and disec-butanolamine, including their various stereoisomers and mixtures thereof. In a preferred embodiment, the alkanolamine (E) comprises at least one selected from isopropanolamine, ethanolamine, propanolamine (3-amino-1-propanol), diethanolamine, and triethanolamine. In a preferred embodiment, from the perspective of ink stability and drying time, the alkanolamine (E) comprises triethanolamine.

[0108] In some embodiments, from the perspective of ink stability and drying time, the content of alkanolamine (E) in the inkjet ink is preferably at least 0.01 wt%, at least 0.05 wt%, at least 0.1 wt%, at least 0.2 wt%, at least 0.4 wt%, at least 0.5 wt%, at least 0.6 wt%, at least 0.8 wt%, at least 1 wt%, at least 2 wt%, at least 3 wt%, at least 4 wt%, and / or preferably at most 5 wt%, at most 4 wt%, at most 3 wt%, at most 2 wt%, at most 1 wt%, at most 0.8 wt%, at most 0.6 wt%, at most 0.5 wt%, at most 0.4 wt%, at most 0.2 wt%, at most 0.1 wt%, and at most 0.05 wt%, relative to the total weight of the inkjet ink. In one embodiment, the content of alkanolamine (E) in the inkjet ink is preferably in the range of 0.01 to 5 wt%, more preferably 0.2 to 2 wt%, even more preferably 0.3 to 1 wt%, and even more preferably 0.4 to 0.6 wt%, based on the total weight of the inkjet ink.

[0109] (F) Surfactants

[0110] In one embodiment, inkjet ink may contain one or more surfactants, taking into account ink stability and wettability on a substrate. Based on the total weight of the inkjet ink, the combined concentration of one or more surfactants present in the inkjet ink is preferably at least 0.01 wt%, at least 0.05 wt%, at least 0.1 wt%, at least 0.15 wt%, at least 0.2 wt%, at least 0.25 wt%, at least 0.3 wt%, at least 0.35 wt%, at least 0.4 wt%, at least 0.45 wt%, at least 0.5 wt%, at least 0.6 wt%, at least 0.8 wt%, at least 1 wt%, at least 2 wt%, at least 3 wt%, at least 4 wt%, and / or preferably at most 5 wt%, at most 4 wt%, at most 3 wt%, at most 2 wt%, at most 1 wt%, at most 0.8 wt%, at most 0.6 wt%, at most 0.5 wt%, at most 0.45 wt%, at most 0.4 wt%, at most 0.35 wt%, at most 0.3 wt%, at most 0.25 wt%, at most 0.2 wt%. wt%, up to 0.15 wt%, up to 0.1 wt%, up to 0.05 wt%.

[0111] Examples of surfactants include, but are not limited to:

[0112] - Anionic surfactants (based on sulfate, sulfonate or carboxylate anions), such as sodium dioctyl sulfosuccinate (DSS), perfluorooctanoate (PFOA or PFO), perfluorooctanesulfonate (PFOS), sodium dodecyl sulfate (SDS), ammonium dodecyl sulfate and other alkyl sulfates, sodium lauryl ether sulfate (SLS, also known as sodium dodecyl ether sulfate (SLES)), alkylbenzene sulfonates, soaps and fatty acid salts;

[0113] - Polysiloxanes, including organically modified silicones (e.g., alkyl, aryl and / or aralkyl modified silicones), such as COATOSIL 1211C and 3573, each available from Momentive;

[0114] -Silicone acrylate copolymers, such as KP-541, KP-543, KP-545, KP-550 and KP-575 (acrylic polymers grafted with polydimethylsiloxane side chains, available from Shin-Etsu Chemical Co., Ltd.) and BYK-3550 (available from BYK Japan KK).

[0115] - Polyether-modified silicones, including block copolymers having a pendant grafted structure formed by a linear or branched polydimethylsiloxane backbone comprising one or more polyether side chains and optionally one or more aliphatic alkyl side chains. Polyether-modified silicones include, but are not limited to, KF-6013 (PEG-9 dimethyl polysiloxane, uncapped, HLB=10.0), KF-6015 (PEG-3 dimethyl polysiloxane, uncapped, HLB=4.5), KF-6017 (PEG-10 dimethyl polysiloxane, uncapped, HLB=4.5), and KF-6038 (lauryl PEG-9 polydimethylsiloxyethyl dimethyl polysiloxane, uncapped, HLB=3.0), all available from Shin-Etsu Chemical Co., and BYK-307 (polyether-modified polydimethylsiloxane) available from BYK Additives & Instruments as described above.

[0116] - Fluoropolymers, such as FC-4430 and FC-4432 available from 3M;

[0117] - Photocrosslinkable silicone acrylates or silicone polyether acrylates, such as TEGO RAD 2100, TEGO RAD 2200, TEGO RAD 2250, and TEGO RAD 2300 (silicone polyether acrylates), each available from Evonik Industries, and BYK-UV 3500 and 3530, available from BYK;

[0118] - Polyacrylates, including polyacrylate copolymers and cross-linked polymers, such as BYK-381 and BYK-361N (polyacrylate copolymers), each available from BYK, and PEMULEN EZ-4U (acrylate / C10-C30 alkyl acrylate cross-linked polymer) and PEMULEN TR-2 (acrylate / C10-C30 alkyl acrylate cross-linked polymer), each available from Lubrizol.

[0119] - Acrylene diols and acetylene diol gemini surfactants, such as SURFYNOLSEF and DYNOL surfactants available from Evonik Industries;

[0120] - Polysiloxane twin surfactants, such as TEGO TWIN 4100 and TEGO TWIN 4200, available from Evonik Industries;

[0121] - Nonionic polyethers, for example, as substrate wetting surfactants, such as TEGO WET 510 (hydrophilic polyether substrate wetting surfactant) available from Evonik Industries.

[0122] - Amides or monoalkanolamides of fatty acids, including alkoxylated monoalkanolamines of fatty acids, such as coconut fatty acid monoethanolamide and coconut fatty acid monoethanolamide reacted with 2-20 moles of ethylene oxide;

[0123] -Ethers, such as alkoxylated C1-C 22 Alcohols, including alkoxylated fatty alcohols such as BIO-SOFT N-600 (C12-C13 alcohol ethoxylate), MAKON DA-4 (ethoxylated isodecyl alcohol), MERPOL SE (alcohol ethoxylate), and POLYSTEP TD-6 (ethoxylated tridecyl alcohol), each available from Stepan; ethylene oxide / propylene oxide copolymers; alkoxylated alkylphenols; and alkyl polysaccharides (APGs), such as those prepared by reacting fatty alcohols with glucose.

[0124] - Fatty esters, such as ethoxylated and / or propoxylated fatty acids (e.g., castor oil containing 2 to 40 moles of ethylene oxide), alkoxylated glycerides (e.g., PEG-24 glyceryl monostearate), glycol esters and derivatives, monoglycerides, polyglycerides, polyol esters and sorbitan / sorbitan esters, such as sorbitan monolaurate (e.g., EMASOL L-10V available from Kao), and polysorbates, including mono-, di- or tri-fatty acid esterified polysorbates such as TOXIMUL SEE-340 (sorbitan trioleate ethoxylate (20)) available from Stepan;

[0125] - Phosphate surfactants, such as alcohol phosphates, alkyl phosphates, alcohol ethoxylated phosphates, tridecyl alcohol ethoxylated phosphates, oleyl alcohol ethoxylated phosphates, alkylphenol ethoxylates, aryl ethoxylated phosphates, nonylphenol ethoxylated phosphates, salts of nonylphenol ethoxylated phosphates, organophosphates, aliphatic phosphates, phosphorylated nonylphenoxypolyethoxyethanol, phosphate coesters of fatty alcohols, or salts of ethylhexanol ethoxylated phosphates (“2EH-2EO”). In one embodiment, the phosphate surfactant is Dephotrope™ CAS-MF. In another embodiment, the phosphate surfactant is Emphos® 9NP, Emphos® CS121, Emphos® CS131, Emphos® CS141, Emphos® CS1361, ESI-Terge® 320, or ESI-Terge® 330. In a preferred embodiment, the phosphate surfactant is Stodex™ PK-80A from Ashland.

[0126] - Glycosides of fatty alcohols, such as PLATNASENS NATURAL EMULSIFIER HE20 (cetearyl glucoside, sorbitol oleate), which is available from Clariant.

[0127] In a preferred embodiment, from the perspective of ink stability and wettability on the substrate, the inkjet ink contains a phosphate coester of a fatty alcohol, such as Stodex™ PK-80N, dioctyl sodium sulfosuccinate (DSS), and / or a siloxane twin surfactant, such as Tego Twin™ 4200.

[0128] Colorant (G)

[0129] The inkjet inks disclosed herein preferably contain a colorant (G) to provide colored inks suitable for a variety of printing purposes, and the inkjet inks are not limited to any particular color. In addition to providing color to the inkjet ink, this colorant (G) can also improve the lightfastness, weather resistance, etc., of the printed image. Any colorant (G) can be used in the inkjet ink to provide the desired color, including dyes, pigments, and mixtures, provided that the colorant (G) can be dissolved or dispersed in the inkjet ink. Suitable colors include, for example, cyan, magenta, yellow and key color (black) (“CMYK”), white, orange, green, light cyan, light magenta, purple, etc., including spot colors and process colors.

[0130] The inks of this invention may also contain dyes known in the field of inkjet printing. For water-based ink compositions, dyes suitable for use in this invention include, but are not limited to, water-soluble reactive dyes, direct dyes, anionic dyes, cationic dyes, acid dyes, food dyes, metal complex dyes, phthalocyanine dyes, anthraquinone dyes, anthraquinone dyes, azo dyes, rhodamine dyes, solvent dyes, etc. Specific examples of dyes that can be used in this invention are as follows: Yellow dyes include: Acid Yellow 1, 3, 11, 17, 19, 23, 25, 29, 36, 38, 40, 42, 44, 49, 59, 61, 70, 72, 75, 76, 78, 79, 98, 99, 110, 111, 127, 131, 135, 142, 162, 164 and 165; Direct Yellow 1, 8, 11, 12, 24, 26, 27, 33, 39, 44, 50, 58, 85, 86, 87, 88, 89, 98, 110, 132, 142 and 144; Reactive Yellow 1, 2, 3, 4, 6, 7, 11, 12, 13, 14, 15, 16, 17, 18, 22, 23, 24, 25, 26, 27, 37 and 42; and Food Yellow 3 and 4; Magenta dyes include: Acid Red 1, 6, 8, 9, 13, 14, 18, 26, 27, 32, 35, 37, 42, 51, 52, 57, 75, 77, 80, 82, 85, 87, 88, 89, 92, 94, 97, 106, 111, 114, 115, 117, 118, 119, 129, 130, 1 31, 133, 134, 138, 143, 145, 154, 155, 158, 168, 180, 183, 184, 186, 194, 198, 209, 211, 215, 219, 249, 252, 254, 262, 265, 274, 282, 289, 303, 317, 320, 321 and 322; Direct red 1, 2, 4, 9, 11, 13, 17, 20, 23, 24, 28, 31, 33, 37, 39, 44, 46, 62, 63, 75, 79, 80, 81, 83 84, 89, 95, 99, 113, 197, 201, 218, 220, 224, 225, 226, 227, 228, 229, 230 and 231; Reactive Red 1, 2, 3, 4, 5, 6, 7, 8, 11, 12, 13, 15, 16, 17, 19, 20, 21, 22, 23, 24, 28, 29, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 45, 46, 49, 50, 58, 59, 63 and 64; and Edible Red 7, 9 and 14;Cyan dyes include: Acid Blue 1, 7, 9, 15, 22, 23, 25, 27, 29, 40, 41, 43, 45, 54, 59, 60, 62, 72, 74, 78, 80, 82, 83, 90, 92, 93, 100, 102, 103, 104, 112, 113, 117, 120, 126, 127, 129, 130, 131, 138, 140, 142, 143, 151, 154, 158, 161, 166, 167, 168, 170, 171, 182, and 183. 184, 187, 192, 199, 203, 204, 205, 229, 234, 236, and 249; Direct Blue 1, 2, 6, 15, 22, 25, 41, 71, 76, 77, 78, 80, 86, 87, 90, 98, 106, 108, 120, 123, 158, 160, 163, 165, 168, 192, 193, 194, 195, 196, 199, 200, 201, 202, 203, 207, 225, 226, 236, 237, 246, 248, and 2 49; Reactive Blue 1, 2, 3, 4, 5, 7, 8, 9, 13, 14, 15, 17, 18, 19, 20, 21, 25, 26, 27, 28, 29, 31, 32, 33, 34, 37, 38, 39, 40, 41, 43, 44 and 46; and CI Edible Blue 1 and 2; Black dyes include: Acid Black 1, 2, 7, 24, 26, 29, 31, 48, 50, 51, 52, 58, 60, 62, 63, 64, 67, 72, 76, 77, 94, 107, 108, 109, 110, 112 Colors 115, 118, 119, 121, 122, 131, 132, 139, 140, 155, 156, 157, 158, 159, and 191; Direct Black 17, 19, 22, 32, 39, 51, 56, 62, 71, 74, 75, 77, 94, 105, 106, 107, 108, 112, 113, 117, 118, 132, 133, 146, 154, and 168; Reactive Black 1, 3, 4, 5, 6, 8, 9, 10, 12, 13, 14, 31, and 18; and Food Black 2. In a preferred embodiment, the colorant may be Orient 191L ​​containing 15 wt% Direct Black 19.

[0131] In some embodiments, considering ink stability and optical density on the substrate, the inkjet ink contains a colorant (G) at a concentration preferably at least 0.1 wt%, at least 0.5 wt%, at least 1 wt%, at least 2 wt%, at least 5 wt%, at least 10 wt%, at least 15 wt%, at least 20 wt%, at least 25 wt%, and / or preferably at most 30 wt%, at most 25 wt%, at most 20 wt%, at most 15 wt%, at most 10 wt%, at most 5 wt%, at most 2 wt%, at most 1 wt%, and at most 0.5 wt%, relative to the total weight of the inkjet ink. In one embodiment, the concentration of the colorant (G) may be in the range of 0.1 to 30 wt%, 15 to 28 wt%, preferably 20 to 25 wt%, relative to the total weight of the inkjet ink.

[0132] (H) Diol Ether

[0133] In some embodiments, the inkjet ink further comprises one or more glycol ethers (H) present in a combined concentration, preferably at least 0.1 wt%, at least 0.2 wt%, at least 0.5 wt%, at least 0.6 wt%, at least 0.8 wt%, at least 1 wt%, at least 1.2 wt%, at least 1.5 wt%, at least 2 wt%, at least 3 wt%, at least 4 wt%, and / or preferably at most 5 wt%, at most 4 wt%, at most 3 wt%, at most 2 wt%, at most 1.5 wt%, at most 1 wt%, at most 0.8 wt%, at most 0.6 wt%, at most 0.5 wt%, and at most 0.2 wt%, relative to the total weight of the inkjet ink. One or more glycol ethers (H) may comprise aliphatic or aromatic glycol ethers, such as aromatic glycol ethers, such as propylene glycol phenyl ether (e.g., Dowanol™ PPh glycol ether), or aliphatic glycol ethers, such as propylene glycol methyl ether, di(ethylene glycol) n-butyl ether (Butyl Carbitol™), poly(ethylene glycol) methyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-propyl ether, ethylene glycol monoisopropyl ether, diethylene glycol monoisopropyl ether, ethylene glycol mono-n-butyl ether, diethylene glycol mono-n-butyl ether, triethylene glycol mono-n-butyl ether, ethylene glycol mono-tert-butyl ether, diethylene glycol mono-tert-butyl ether, 1-methyl-1-methoxybutanol, propylene glycol monomethyl ether (Dowanol™ PM), propylene glycol monoethyl ether, propylene glycol monotert-butyl ether, propylene glycol mono-n-propyl ether, propylene glycol monoisopropyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol mono-n-propyl ether, dipropylene glycol monoisopropyl ether, propylene glycol mono-n-butyl ether and dipropylene glycol mono-n-butyl ether; formamide, acetamide, dimethyl sulfoxide, sorbitol, sorbitan, glyceryl monoacetate, glyceryl diacetate, glyceryl triacetate and sulfolane; or combinations thereof. In one embodiment, from the perspective of drying time and wettability on the substrate, one or more glycol ethers (H) are glycol ether DH.

[0134] (I) Additives

[0135] In some implementations, inkjet inks may contain one or more additional components or additives to improve various ink properties and performance.

[0136] resin dispersion

[0137] In some embodiments, inkjet inks may contain a resin dispersion. There are no particular limitations on the resin dispersion, as long as the resin in the dispersion is dispersed in fine particles within the dispersion medium. Examples of resin dispersions include dispersions, suspensions, and emulsions.

[0138] Examples of resin dispersions are not particularly limited, including: emulsions of polyurethane resins represented by polyether-type polyurethane resins, polyester-type polyurethane resins containing ester bonds in the main chain, or polycarbonate-type polyurethane resins containing carbonate bonds in the main chain, as well as (meth)acrylic resin emulsions and styrene-(meth)acrylic copolymer resin emulsions. Furthermore, the aforementioned copolymers can be any form of random copolymer, block copolymer, alternating copolymer, and graft copolymer.

[0139] Resin dispersions can be used alone, or in combination of two or more.

[0140] By incorporating a resin dispersion, the resin and pigment in the ink composition fuse together upon drying. When this occurs, the pigment is fixed to the fabric, or the resin film is fixed to the fabric, which helps to improve the rub resistance and wash fastness of the image portion of the recorded object.

[0141] Other additives include:

[0142] - pH adjusters, including but not limited to potassium dihydrogen phosphate, disodium hydrogen phosphate, sodium hydroxide, lithium hydroxide, potassium hydroxide, ammonia, diethanolamine, triethanolamine, triisopropanolamine, potassium carbonate, sodium carbonate and sodium bicarbonate;

[0143] - Preservatives and / or bactericides, including but not limited to sodium benzoate, sodium pentachlorophenolate, sodium pyrithione, sodium sorbate, sodium dehydroacetate and 1,2-dibenzisothiazolin-3-one;

[0144] - Antiscaling agents, stabilizers, humectants, safety marking agents, some other resins, adhesives, tackifiers, binder substances, rust inhibitors, or other inkjet ink additives known to those skilled in the art;

[0145] - and similar substances, including mixtures thereof.

[0146] In one embodiment, the additive (I) may comprise a surfactant to complement or replace one or more surfactants (F). Examples of surfactants include, but are not limited to:

[0147] - Polysiloxanes, including amine-modified silicones and organic-modified silicones (e.g., alkyl, aryl and / or aralkyl-modified silicones), such as COATOSIL 1211C and 3573, each available from Momentive;

[0148] -Silicone acrylate copolymers, such as KP-541, KP-543, KP-545, KP-550 and KP-575 (acrylic polymers grafted with polydimethylsiloxane side chains, available from Shin-Etsu Chemical Co., Ltd.) and BYK-3550 (available from BYK Japan KK).

[0149] - Polyether-modified silicones, including block copolymers having a pendant grafted structure formed by a linear or branched polydimethylsiloxane backbone comprising one or more polyether side chains and optionally one or more aliphatic alkyl side chains. Polyether-modified silicones include, but are not limited to, KF-6013 (PEG-9 dimethyl polysiloxane, uncapped, HLB=10.0), KF-6015 (PEG-3 dimethyl polysiloxane, uncapped, HLB=4.5), KF-6017 (PEG-10 dimethyl polysiloxane, uncapped, HLB=4.5), and KF-6038 (lauryl PEG-9 polydimethylsiloxyethyl dimethyl polysiloxane, uncapped, HLB=3.0), all available from Shin-Etsu Chemical Co., and BYK-307 (polyether-modified polydimethylsiloxane), available from BYK Additives & Instruments.

[0150] - Fluoropolymers, such as FC-4430 and FC-4432 available from 3M;

[0151] - Photocrosslinkable silicone acrylates or silicone polyether acrylates, such as TEGO RAD 2100, TEGO RAD 2200, TEGO RAD 2250, and TEGO RAD 2300 (silicone polyether acrylates), each available from Evonik Industries, and BYK-UV 3500 and 3530, available from BYK;

[0152] - Polyacrylates, including polyacrylate copolymers and cross-linked polymers, such as BYK-381 and BYK-361N (polyacrylate copolymers), each available from BYK, and PEMULEN EZ-4U (acrylate / C10-C30 alkyl acrylate cross-linked polymer) and PEMULEN TR-2 (acrylate / C10-C30 alkyl acrylate cross-linked polymer), each available from Lubrizol.

[0153] - Acrylene diols and acetylene diol gemini surfactants, such as SURFYNOLSEF and DYNOL surfactants available from Evonik Industries;

[0154] - Polysiloxane twin surfactants, such as TEGO TWIN4100 available from Evonik Industries;

[0155] - Nonionic polyethers, for example, as substrate wetting surfactants, such as TEGO WET 510 (hydrophilic polyether substrate wetting surfactant) available from Evonik Industries.

[0156] - Amides or monoalkanolamides of fatty acids, including alkoxylated monoalkanolamines of fatty acids, such as coconut fatty acid monoethanolamide and coconut fatty acid monoethanolamide reacted with 2-20 moles of ethylene oxide;

[0157] -Ethers, such as alkoxylated C1-C 22 Alcohols, including alkoxylated fatty alcohols such as BIO-SOFT N-600 (C12-C13 alcohol ethoxylate), MAKON DA-4 (ethoxylated isodecyl alcohol), MERPOL SE (alcohol ethoxylate), and POLYSTEP TD-6 (ethoxylated tridecyl alcohol), each available from Stepan; ethylene oxide / propylene oxide copolymers; alkoxylated alkylphenols; and alkyl polysaccharides (APGs), such as those prepared by reacting fatty alcohols with glucose.

[0158] - Fatty esters, such as ethoxylated and / or propoxylated fatty acids (e.g., castor oil containing 2 to 40 moles of ethylene oxide), alkoxylated glycerides (e.g., PEG-24 glyceryl monostearate), glycol esters and derivatives, monoglycerides, polyglycerides, polyol esters and sorbitan / sorbitan esters, such as sorbitan monolaurate (e.g., EMASOL L-10V available from Kao), and polysorbate esters, including mono-, di-, or tri-fatty acid esterified polysorbate esters such as TOXIMUL SEE-340 (sorbitan trioleate ethoxylate (20)) available from Stepan; and

[0159] - Glycosides of fatty alcohols, such as PLATNASENS NATURAL EMULSIFIER HE20 (cetearyl glucoside, sorbitan oleate), which is available from Clariant.

[0160] The concentration of any of the additives listed above, including surfactants and resin dispersions, in any inkjet ink of this disclosure, relative to the total weight of the inkjet ink, may be at least 0.0001 wt%, at least 0.0005 wt%, at least 0.001 wt%, at least 0.005 wt%, at least 0.01 wt%, at least 0.05 wt%, at least 0.1 wt%, at least 0.2 wt%, at least 0.4 wt%, at least 0.5 wt%, at least 0.7 wt%, at least 1 wt%, at least 1.2 wt%, at least 1.5 wt%, at least 1.7 wt%, at least 2 wt%, at least 2.5 wt%, at least 3 wt%, at least 3.5 wt%, at least 4 wt%, at least 4.5 wt%, at least 5 wt%, at least 6 wt%, at least 7 wt%, at least 8 wt%, at least 9 wt%, at least 10 wt%, at least 12 wt%, at least 15 wt%, at least 16 wt%, at least 20 wt%, at least 25 wt%, at least 30 wt%. wt%, and / or up to 35 wt%, up to 30 wt%, up to 25 wt%, up to 20 wt%, up to 16 wt%, up to 15 wt%, up to 12 wt%, up to 10 wt%, up to 9 wt%, up to 8 wt%, up to 7 wt%, up to 6 wt%, up to 5 wt%, up to 4.5 wt%, up to 4 wt%, up to 3.5 wt%, up to 3 wt%, up to 2.5 wt%, up to 2 wt%, up to 1.7 wt%, up to 1.5 wt%, up to 1.2 wt%, up to 1 wt%, up to 0.7 wt%, up to 0.5 wt%, up to 0.4 wt%, up to 0.2 wt%, up to 0.1 wt%, up to 0.05 wt%, up to 0.01 wt%, up to 0.005 wt%, up to 0.001 wt%, up to 0.0005 wt%.

[0161] Alternatively, the inkjet ink may contain no or substantially no of any of the additives or compounds listed above, including surfactants, meaning that the concentration of such additives or compounds in the inkjet ink is less than 1 wt%, less than 0.5 wt%, less than 0.1 wt%, less than 0.05 wt%, less than 0.001 wt%, less than 0.0001 wt%, less than 0.00001 wt%, or 0 wt%.

[0162] In one embodiment, the inkjet ink contains less than 5 wt% glycerol and / or 1,3-propanediol, preferably less than 4 wt%, less than 3 wt%, less than 2 wt%, preferably less than 1 wt%, more preferably less than 0.5 wt%, or 0 wt%. In one embodiment, the inkjet ink is substantially free of glycerol, 1,3-propanediol, lauric acid, and / or resins.

[0163] Preparation method

[0164] The inkjet inks described herein can be prepared by any suitable technique known to those skilled in the art, for example by combining in any order: a fatty acid (A) comprising oleic acid or a fatty acid with a melting point not exceeding 25°C, a first straight-chain alkane 1,2-diol (B1) having a carbon chain of 2 to 4 carbon atoms, a second straight-chain alkane 1,2-diol (B2) having a carbon chain of 5 to 14 carbon atoms, an organic solvent (C), and water (D), followed by stirring, agitation, and / or homogenization at a temperature of 20 to 100°C for an appropriate time to form a homogeneous solution.

[0165] In one embodiment, inkjet ink can be prepared by first combining fatty acid (A), first and second straight-chain alkane 1,2-diols ((B1), (B2)), organic solvent (C), water (D), and any optional resin, solvent, surfactant, or other additive in a container, followed by stirring for at least 10 minutes. Then, a colorant (G) can be added as a final component, stirring continues, and the solution can be mixed for at least 10 minutes to obtain inkjet ink. The resulting inkjet ink can then be placed in a printer cartridge, such as the HP45Si printer cartridge manufactured by Hewlett Packard, the FUNAI TIJ cartridge manufactured by Funai Co., or some other suitable printhead.

[0166] performance

[0167] The inkjet inks disclosed herein have an extended open-cap time within a certain temperature and humidity range, for example, through side-fire printing. The inkjet ink is exposed to air (open cartridge) for a specific time (e.g., 1 minute, 10 minutes, 30 minutes, 60 minutes, etc.), and the same image is reprinted via side-fire printing. The reprinted image after opening is then compared to the original image to determine whether line loss / loss of line sharpness occurs in narrow-line images. Throughout the open-cap time, the inkjet printhead maintains the same orientation (i.e., side-fire ink). If no line loss / loss of sharpness occurs within the test interval, the inkjet ink is awarded a "Good" (G) open-cap rating for that interval. If 1-10 lines are lost / sharpened within the test interval, but not significantly affecting image sharpness or readability, the inkjet ink is given an "Acceptable" (A) open-cap rating for that interval. If more than 10 lines are lost / sharpened and / or readability is substantially reduced within the test interval, the inkjet ink is classified as "Bad" (NG) for that interval. Suitable inkjet inks are those that achieve an "acceptable" or "good" open-cap rating after being opened (i.e., exposed to air) for more than 30 seconds, preferably more than 1 minute, more preferably more than 10 minutes, even more preferably more than 30 minutes, and still more preferably more than 60 minutes. Inkjet inks that exhibit an "acceptable" or "good" open-cap rating over a longer period are considered to have good "intermittent printing performance".

[0168] The inkjet inks disclosed in this article can also be characterized by long operational stability (also known as ink life or print life). To test the operational stability of the inkjet inks, the printhead nozzles were visually observed after printing 3600 pages continuously.

[0169] In cases of excessive ink buildup (e.g., see using ink-2) Figure 1A This was rated "Not Good" (NG). This ink buildup is due to dripping. There is absolutely no ink buildup (e.g., see using Ink-1). Figure 1B The ink was rated "Good" (G). Slight ink buildup (e.g., see using ink-17) was also noted. Figure 1C It was rated "Acceptable" (A).

[0170] printed matter

[0171] The printed matter of the present invention comprises a substrate and a dried form of the inkjet ink of the present invention disposed on the substrate by side spraying.

[0172] Inkjet inks can be side-printed onto a variety of substrates, including three-dimensional parts and flat or roll stock supplied in roll form, for the manufacture of a wide range of printed materials. During printing, the substrate is positioned substantially vertically. While planar substrates are suitable for forming printed materials, a particular advantage of this disclosure is that the disclosed inkjet inks have long-distance projection capabilities, enabling the formation of printed images on complex three-dimensional substrates, such as radial, curved, serrated, corrugated, grooved, flanged, and / or substrates with structured surfaces (e.g., granular surfaces), all of which are notoriously difficult substrates because the ink must travel long distances to reach all parts of the complex surface. Printed materials may be suitable for graphic arts, textiles, packaging (such as food packaging, pharmaceutical packaging, etc.), lotteries, direct mail, business forms, and the publishing industry. Examples include signage or labels, lotteries, publications, packaging (such as food packaging, pharmaceutical packaging, blister packaging, and various other flexible packaging), folding cartons, rigid containers (such as plastic cups or buckets, glass containers, metal cans, PET bottles, jars, and tubes), envelopes, corrugated cardboard, point-of-sale displays, etc. Particularly preferred printed materials are those with inkjet inks applied to complex three-dimensional portions of the printed material via side-jet printing, for example, where the printed image is located on the grooved or corrugated portion of a plastic container, or on the concave dome-shaped bottom of a metal can.

[0173] Inkjet inks can be printed on porous (or permeable) substrates, examples of which include, but are not limited to, uncoated paper, wood, films, corrugated (cardboard / fiberboard) and fabrics (including but not limited to woven fabrics, nonwoven fabrics and foil laminates).

[0174] Inkjet inks can also be printed on non-porous (or impermeable) substrates, such as various plastics, glass, metals (e.g., steel, aluminum) and / or non-permeable papers (e.g., coated papers such as varnish-coated paper), including but not limited to molded plastic or metal parts and sheets or rolls of plastic 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 papers such as varnish-coated paper, and metals such as steel and aluminum.

[0175] Methods for creating printed images

[0176] The method for forming a printed image on a substrate according to the present invention includes: applying the inkjet ink of the present invention laterally to the substrate using a thermal inkjet printhead, and then drying the inkjet ink.

[0177] For side-jet printing, the desired printed image is formed when a precise dot pattern is horizontally ejected from an ink droplet generating device called the printhead onto the printing medium.

[0178] In one embodiment, the straight line along the shortest distance between the nozzle of the thermal inkjet printhead supplying ink and the substrate forms a minimum angle with the direction of gravity within the range of 70° to 90°, preferably 80° to 90°, more preferably 85° to 90°, or approximately 90° (vertical). In this embodiment, the ink can be considered to be ejected laterally, horizontally, or perpendicular to gravity. In one embodiment, the substrate is placed substantially vertically during printing, meaning that the normal drawn from the substrate forms a minimum angle with the direction of gravity within the aforementioned range.

[0179] The printhead has a set of precisely formed nozzles located on a nozzle plate and attached to an inkjet printhead substrate. The inkjet printhead substrate contains a set of firing chambers that receive inkjet ink through fluid communication with one or more ink reservoirs. Each firing chamber has a resistive element called a firing resistor positioned opposite the nozzle, allowing inkjet ink to collect between the firing resistor and the nozzle. Each resistive element is typically a pad of resistive material and is, for example, about 35 μm × 35 μm in size. The printhead is held and protected by an outer casing called a print cartridge or inkjet pen. When a specific resistive element is energized, droplets of inkjet ink are ejected through the nozzle toward the printing medium. The ejection of the ink droplets is typically controlled by a microprocessor, whose signal is transmitted via electrical traces to the resistive element, thus forming alphanumeric and other image patterns on the printing medium. Because the nozzles are very small, typically 10 μm to 40 μm in diameter, ink that minimizes clogging is desirable. In particular, due to the open-atmosphere printhead design used in thermal inkjet (TIJ) printing (where the nozzle orifice is open to the atmosphere without valve seals to allow ink pressurization), TIJ printing has historically performed poorly during intermittent printing. This is because the cap-opening time (printing idle time) causes the ink inside and around the nozzle to dry prematurely, especially in cold, dry environments. For typical inkjet inks, in the context of side-jet printing, the cap-opening time for printing acceptable images is shortened. Here, the horizontal path of the ink leads to more ink buildup and clogging around the nozzle.

[0180] This disclosure provides a method for forming a printed image by side-printing any inkjet ink from one or more embodiments of this disclosure onto a substrate using a thermal inkjet printhead and drying the inkjet ink. Using the inkjet inks described herein overcomes the problem typically associated with thermal inkjet processes: short cap opening times (too rapid solvent loss) within certain temperature and humidity ranges.

[0181] Any on-demand inkjet printhead known to those skilled in the art of inkjet printing can be used as a printing unit in the method of this invention, including continuous printheads, thermal printheads, electrostatic printheads, and acoustic printheads, with thermal printheads (with thermal transducers) being preferred. Typical parameters, such as print resolution, print speed, printhead pulse-up temperature, drive voltage, and pulse length, can be adjusted according to the printhead specifications. Printheads typically suitable for the method herein have droplet sizes in the range of 2 to 80 pL and droplet frequencies in the range of 10 to 100 kHz. High-quality printing can be achieved, 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-up temperature to 25 to 45°C, and the pulse length to 0.7 to 2.5 microseconds, although values ​​higher or lower can also be used with satisfactory printing. An example of a non-limiting printhead applicable to the disclosed method is the HP45Si printer cartridge manufactured by Hewlett Packard, or the FUNAI TIJ cartridge manufactured by FUNAI Co.

[0182] After application, the inkjet ink is dried. In some embodiments, external heat may be applied to dry the applied inkjet ink, such as using a heater. However, it is preferable not to apply external heat to promote drying or increase the drying rate. Therefore, in a preferred embodiment, drying is achieved by allowing the applied inkjet ink to dry under ambient conditions for less than 30 seconds, preferably less than 25 seconds, more preferably less than 20 seconds, even more preferably less than 15 seconds, even more preferably less than 10 seconds, without using an external heat source, such as a heater. The drying time may be increased or decreased based on ambient temperature and humidity. Furthermore, the method disclosed herein does not require energy curing (e.g., UV or electron beam curing). Once the applied ink is considered dry, a coating of inkjet ink may be further applied, or any processing steps known to those skilled in the art may be performed as needed.

[0183] It should also be recognized that, prior to applying inkjet ink, substrate surface treatments, such as corona treatment, atmospheric plasma treatment, and flame treatment, can be optionally employed in the methods described herein to improve the properties of the printed material, such as ink adhesion. The parameters of such substrate surface treatments can vary considerably depending on the substrate material to be printed, the specific inkjet ink used, the printing method applied, and the desired properties and application of the printed material.

[0184] The following examples are intended to further illustrate implementations of the inkjet inks of this disclosure, and are not intended to limit the scope of the claims.

[0185] The following clauses further illustrate the implementation of inkjet inks, the method of forming printed images on a substrate by side-printing, and the uses of inkjet inks.

[0186] <1>

[0187] An inkjet ink for printing onto a substrate by side-jetting with an inkjet printhead, wherein the inkjet ink comprises:

[0188] (A) Oleic acid content of 0.2 to 1.5 wt% based on the total weight of the inkjet ink;

[0189] (B1) 1,2-propanediol in a content of 1 to 10 wt% based on the total weight of the inkjet ink;

[0190] (B2) 1,2-hexanediol in a content of 0.1 to 10 wt% based on the total weight of the inkjet ink;

[0191] (C) Dimethyl sulfone, in a content of 1 to 20 wt%, based on the total weight of the inkjet ink; and

[0192] (D) Water,

[0193] The weight ratio of 1,2-propanediol to 1,2-hexanediol in the inkjet ink is 1.7:1 to 2:1.

[0194] <2>

[0195] An inkjet ink for printing by side-ejection onto a substrate using an inkjet printhead, wherein the inkjet ink comprises:

[0196] (A) Oleic acid content of 0.2 to 1.5 wt% based on the total weight of the inkjet ink;

[0197] (B1) 1,2-propanediol in a content of 1 to 10 wt% based on the total weight of the inkjet ink;

[0198] (B2) 1,2-hexanediol in a content of 0.1 to 10 wt% based on the total weight of the inkjet ink;

[0199] (C) Dimethyl sulfone in a content of 1 to 20 wt% based on the total weight of the inkjet ink;

[0200] (E) Triethanolamine, at a content of 0.1 to 1 wt%, based on the total weight of the inkjet ink; and

[0201] (D) Water,

[0202] The weight ratio of 1,2-propanediol to 1,2-hexanediol in the inkjet ink is 1.7:1 to 2:1.

[0203] <3>

[0204] A method for forming a printed image on a substrate by side-printing, wherein the method includes:

[0205] Use a thermal inkjet printhead <1> to <2> The inkjet ink described in any one of the claims is applied laterally to the substrate; and

[0206] Dry the inkjet ink.

[0207] <4>

[0208] <1> to <3> The use of any one of the inkjet inks in printing by side-jetting onto a substrate using an inkjet printhead.

[0209] Example

[0210] Material

[0211] Diol ether DH is DOWANOL EPh6 obtained from Dow Chemical Company. It is a polyethylene glycol phenyl ether with a molecular weight of 358 g / mol for its main component.

[0212] STRODEX PK-80N is a phosphate ester surfactant available from Ashland Specialty Chemical.

[0213] TEGO TWIN 4200 is a siloxane-based gemini surfactant available from Evonik Industries.

[0214] PELEX OT-P is a sodium dioctyl sulfosuccinate (DSS) available from Kao Chemicals.

[0215] LUNAC OV is an oleic acid that is available from Kao Chemicals.

[0216] ORIENT 191L ​​is a colorant solution containing 15 wt% Direct Black 19 (a water-soluble dye). ORIENT 191L ​​is available from Orient Chemical Industries Co., Ltd.

[0217] Inkjet ink examples

[0218] Tables 1 through 8 provide examples of inkjet inks, with comparative examples indicated by an asterisk. The amount of each component is expressed as a weight percentage based on the total weight (100%) of the inkjet ink. The compound name of the trade name is indicated above. ORIENT 191L, listed in Tables 1 through 8, is a 15 wt% aqueous solution of Direct Black 19.

[0219] Preparation method

[0220] The inkjet ink was obtained by mixing dimethyl sulfone and water using a stirrer until the dimethyl sulfone was completely dissolved. Then, a co-solvent was added dropwise to the mixture and mixed for at least 15 minutes. Afterward, the colorant was added and mixed for at least 15 minutes to obtain the inkjet ink. The ink was then evaluated as described below, and the results are summarized in Tables 1 through 8.

[0221] Inkjet ink evaluation methods

[0222] Preparation of printed samples

[0223] Inkjet ink examples were evaluated using an HP45Si printer cartridge manufactured by Hewlett Packard on a TIJ printer manufactured by HAS. The TIJ printer was housed in a temperature- and humidity-controlled chamber manufactured by Espec, called an EPL-3H.

[0224] Opening time evaluation

[0225] To evaluate the opening time, the following printing conditions were used:

[0226] - Printing mode: Side-fire printing, where the nozzle surface of the print cartridge is set to be tilted at approximately 90 degrees from the horizontal plane and printing is performed.

[0227] - Printing substrate; plain (uncoated) paper

[0228] - Print resolution: 300dpi x 300dpi (portrait x landscape)

[0229] Printing speed: 7 m / min

[0230] - Pulse width: 1.8 μs

[0231] - Voltage: 8.6 V

[0232] - Pulse heating: Off

[0233] - Printed image: 100% duty cycle (monochrome bitmap) (see example) Figure 2A-2B (and 3A-3B).

[0234] The image is 1.2 cm high and 4.8 cm long (0.5 inches × 1.9 inches).

[0235] - Printing environment: 10℃ (50℉), relative humidity 30% or 35℃ (95℉), relative humidity 85%. Figure 2A-2B Both 3A and 3B were printed at 35℃ and 85% relative humidity.

[0236] Print an image containing a sequence of numbers to confirm that there are no missing or unclear lines (indicating nozzle clogging or missing lines). After confirmation, leave the printhead open for a specific time (1 minute, 3 minutes, 5 minutes, 10 minutes, 15 minutes, 30 minutes, 45 minutes, or 60 minutes), and then reprint the same image. Check the reprinted image (after the specific time interval) to determine if any line loss / loss of line sharpness has occurred. If no line loss / loss of line sharpness has occurred, the inkjet ink is given a "Good" (G) open-cap rating for that time interval. Figure 3B This is an example of inkjet ink printing with an open-cap rating of "Good". If 1-10 lines are lost within a test interval, or if sharpness is lost but not significantly affecting the image's sharpness or readability within that interval, the inkjet ink is given an "Acceptable" (A) open-cap rating for that interval. If more than 10 lines are lost within a test interval, or if sharpness and / or readability are significantly lost, the inkjet ink is classified as "Poor" for that interval.

[0237] Figure 2A-2B Both 3A and 3B were printed at 35℃ and 85% relative humidity. Figure 2A and 2B Printed using comparative example ink-2, and Figure 3A and 3B Print using the ink-1 of this invention. Figure 2B This illustrates an example of inkjet ink printing classified as "poor". Suitable / ideal inkjet inks are those that achieve an "acceptable" or "good" open-cap classification when opened (i.e., exposed to air) at each test interval and under environmental conditions. For example, Figure 3B This table shows an example of inkjet ink printing classified as "good". Table 1. Inkjet ink compositions with operational stability and cap opening result 1.

[0238]

[0239] G = Good; A = Acceptable; NG = Bad

[0240] Table 2. Inkjet ink compositions exhibiting operational stability and capping result 2

[0241]

[0242] Table 3. Inkjet ink compositions exhibiting operational stability and capping results 3

[0243]

[0244] Table 4. Inkjet ink compositions exhibiting operational stability and capping result 4

[0245]

[0246] Table 5. Inkjet ink compositions exhibiting operational stability and capping result 5

[0247]

[0248] Table 6. Inkjet ink compositions exhibiting operational stability and capping results 6

[0249]

[0250] Table 7. Inkjet ink compositions exhibiting operational stability and capping results 7

[0251]

[0252] Table 8. Inkjet ink compositions exhibiting operational stability and capping results of 8.

[0253]

[0254] Inkjet ink performance

[0255] As can be seen from Tables 1, 3 and 5-7, the combination of unsaturated fatty acids, first and second straight-chain alkane 1,2-diols and organic solvents produced significant effects on operational stability and cap opening time when side-printing at different temperatures and humidity levels (see Examples 1, 3, 4, 9, 11, 13, 15 and 17).

[0256] Conversely, inkjet inks formulated with 1,3-propanediol or glycerol instead of one of the straight-chain alkane 1,2-diols exhibited poorer cap-opening behavior and operational stability (see Comparative Examples 7 and 8 in Table 4). Inkjet inks formulated with lauric acid (melting point 43°C) as the fatty acid (see Comparative Example 5 in Table 3) exhibited poorer performance compared to inkjet inks containing equal weight percentages of oleic acid, linoleic acid, and transoleic acid (see Examples 1, 3, and 4 in Table 3, respectively). Examples 1 and 17 in Table 1 show that dimethyl sulfone or 2-pyrrolidone can be used as solvents for beneficial effects on operational stability and cap-opening behavior.

Claims

1. An inkjet ink for printing onto a substrate by side-jetting with an inkjet printhead, wherein, The inkjet ink comprises: (A) Fatty acids containing unsaturated fatty acids; (B1) A first straight-chain alkane, 1,2-diol, having a carbon chain of 2 to 4 carbon atoms; (B2) A second straight-chain alkane, 1,2-diol, having a carbon chain of 5 to 14 carbon atoms; (C) Organic solvents; and (D) Water, Wherein, based on the total weight of the inkjet ink, the contents of the first straight-chain alkane 1,2-diol (B1) and the second straight-chain alkane 1,2-diol (B2) are each independently 0.1 to 10 wt.

2. The inkjet ink according to claim 1, wherein, The organic solvent (C) comprises dimethyl sulfone or 2-pyrrolidone, and the content of dimethyl sulfone or 2-pyrrolidone in the inkjet ink is 2 to 20 wt% based on the total weight of the inkjet ink.

3. The inkjet ink according to claim 1 or 2, wherein, The organic solvent (C) contains dimethyl sulfone.

4. The inkjet ink according to any one of claims 1 to 3, wherein, Based on the total weight of the inkjet ink, the water (D) content is 40 to 80 wt%.

5. The inkjet ink according to any one of claims 1 to 4, wherein, Based on the total weight of the inkjet ink, the content of fatty acid (A) is 0.1 to 5 wt%.

6. The inkjet ink according to any one of claims 1 to 5, wherein, The fatty acid (A) includes oleic acid and / or linoleic acid.

7. The inkjet ink according to any one of claims 1 to 6, wherein, Based on the total weight of the inkjet ink, the content of the combination of the first straight-chain alkane 1,2-diol and the second straight-chain alkane 1,2-diol (B1) + (B2) in the inkjet ink is 5 to 20 wt%.

8. The inkjet ink according to any one of claims 1 to 7, wherein, The first straight-chain alkane 1,2-diol (B1) is 1,2-propanediol, and The second straight-chain alkane 1,2-diol (B2) is 1,2-hexanediol.

9. The inkjet ink according to claim 8, wherein, The weight ratio of 1,2-propanediol to 1,2-hexanediol is 1:1 to 10:

1.

10. The inkjet ink according to any one of claims 1 to 9, wherein, The inkjet ink also contains (E) alkanolamine.

11. The inkjet ink according to claim 10, wherein, The content of the alkanolamine (E) is 0.01 to 5 wt% based on the total weight of the inkjet ink.

12. The inkjet ink according to claim 10 or 11, wherein, The alkanolamine (E) is selected from at least one of ethanolamine, propanolamine, isopropanolamine, diethanolamine, and triethanolamine.

13. The inkjet ink according to any one of claims 1 to 12, wherein, The inkjet ink also contains one or more surfactants (F), in an amount of 0.01 to 5 wt% based on the total weight of the inkjet ink.

14. The inkjet ink according to any one of claims 1 to 13, wherein, The inkjet ink also contains (G) a colorant.

15. The inkjet ink according to claim 14, wherein, The content of the colorant (G) is 0.1 to 30 wt% based on the total weight of the inkjet ink.

16. The inkjet ink according to any one of claims 1 to 15, wherein, The inkjet ink also contains one or more glycol ethers (H), the total content of which is 0.1 to 5.0 wt% based on the total weight of the inkjet ink.

17. A method for forming a printed image on a substrate by side-printing, wherein, The method includes: The inkjet ink of any one of claims 1 to 16 is laterally applied to the substrate using a thermal inkjet printhead; and Dry the inkjet ink.

18. The method according to claim 17, wherein, The minimum angle between the straight line along the shortest distance between the nozzle of the thermal inkjet printhead supplying the inkjet ink and the substrate and the direction of gravity is in the range of 70° to 90°.

19. Use of the inkjet ink according to any one of claims 1 to 16 in printing by side-jetting onto a substrate with an inkjet printhead.

Images